Inkjet Printing methods and ink sets
Abstract
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Projected expiry 21 December 2026, counted from filing; an application has no term until it is granted.
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20 claims: 9 independent, 11 dependent
- 1Zastrzeżenia patentowe 1. Sposób drukowania strumieniowego, znamienny tym, że obejmuje kolejno następujące etapy, w których:a) do drukarki strumieniowej dostarcza się co najmniej dwie lub więcej bezbarwnych cieczy posiadających różne kompozycje i co najmniej jeden kolorowy tusz do drukarki strumieniowej;b) miesza się wymieniony kolorowy tusz do drukarki strumieniowej w kontrolowanej ilości z wymienionymi dwoma lub kilkoma bezbarwnymi cieczami;i c) prowadzi się drukowanie mieszaniną tuszów obejmującą wymieniony kolorowy tusz do drukarki strumieniowej i dwie lub więcej bezbarwnych cieczy z zastosowaniem drukarki strumieniowej na materiale przyjmującym tusz;znamienny tym, że co najmniej jeden kolorowy tusz do drukarki strumieniowej zawiera co najmniej jeden barwnik, a wspomnianym barwnikiem jest pigment.
- 2Sposób drukowania strumieniowego według zastrz. 1, znamienny tym, że kolorowy tusz do drukarki strumieniowej rozcieńcza się mieszaniną wymienionych dwóch lub więcej bezbarwnych cieczy.
- 3Sposób drukowania strumieniowego według zastrz. 1 albo 2, znamienny tym, że kolorowy tusz do drukarki strumieniowej rozcieńcza się z zastosowaniem co najmniej jednej bezbarwnej cieczy w komorze mieszania.
- 4Sposób drukowania strumieniowego według któregokolwiek z zastrz. 1-3, znamienny tym, że kolorowy tusz do drukarki strumieniowej rozcieńcza się z zastosowaniem co najmniej jednej bezbarwnej cieczy w głowicy drukującej drukarki strumieniowej.
- 5Sposób drukowania strumieniowego według któregokolwiek z zastrz. 1-4, znamienny tym, że stosuje się dwie lub więcej bezbarwnych cieczy, które mają różne napięcia powierzchniowe.
- 6Sposób drukowania strumieniowego według któregokolwiek z zastrz. 1-5, znamienny tym, że ilości dwóch lub więcej bezbarwnych cieczy stosowanych w mieszaninie tuszu wybiera się na podstawie testu drukowania, w którym pewną liczbę różnych mieszanin tuszów drukuje się na materiale przyjmującym tusz.
- 7Sposób drukowania strumieniowego według zastrz. 6, znamienny tym, że wyniki testu drukowania są przechowywane w bibliotece danych.
- 8Sposób drukowania strumieniowego według zastrz. 7, znamienny tym, że biblioteka danych zawiera informacje dotyczące jakości obrazu i/lub właściwości fizycznych mieszanin tuszów dla wielu materiałów przyjmujących tusz.
- 9Sposób drukowania strumieniowego według zastrz. 8, znamienny tym, że biblioteka danych jest przechowywana w pamięci i zarządzana przez komputer.
- 10Sposób drukowania strumieniowego według któregokolwiek z zastrz. 1-9, znamienny tym, że ilości dwóch lub więcej bezbarwnych cieczy stosowanych w mieszaninie tuszu bierze się z biblioteki danych, zawierającej informacje dotyczące jakości obrazu i/lub właściwości fizycznych mieszanin kolorowego tuszu do drukarki strumieniowej i dwóch lub więcej bezbarwnych cieczy.
- 11Zest aw kolorowych tuszów do drukarki strumieniowej zawierający dwie lub więcej bezbarwnych cieczy posiadających różne kompozycje i co najmniej jeden kolorowy tusz do drukarki strumieniowej, znamienny tym, że co najmniej jeden kolorowy tusz do drukarki strumieniowej zawiera co najmniej jeden barwnik, a wspomniany barwnik jest pigmentem.
- 12Zest aw kolorowych tuszów do drukarki strumieniowej według zastrz. 11, znamienny tym, że zawiera zdolny do polimeryzacji związek, którego ilość i/lub typ w bezbarwnej cieczy różni się od ilości i/lub typu tego związku w kolorowym tuszu do drukarki strumieniowej.
- 13Zest aw kolorowych tuszów do drukarki strumieniowej według zastrz. 11 albo 12, znamienny tym, że napięcie powierzchniowe bezbarwnej cieczy różni się o więcej niż 3,0 mN/m od napięcia powierzchniowego kolorowego tuszu do drukarki strumieniowej.
- 14Zest aw kolorowych tuszów do drukarki strumieniowej według zastrz. 11 albo 13, znamienny tym, że lepkość bezbarwnej cieczy różni się o więcej niż 5,0 mPa.s w temperaturze 30°C i przy szybkości ścierania wynoszącej 100 s -1 od lepkości kolorowego tuszu do drukarki strumieniowej.
- 15Zest aw kolorowych tuszów do drukarki strumieniowej według któregokolwiek z zastrz. 11-14, znamienny tym, że zawiera inicjator, którego ilość i/lub typ w bezbarwnej cieczy różni się od ilości i/lub typu tego inicjatora w kolorowym tuszu do drukarki strumieniowej.
- 16Zest aw kolorowych tuszów do drukarki strumieniowej według któregokolwiek z zastrz. 11-15, znamienny tym, że zawiera synergetyk polimeryzacji, którego ilość i/lub typ w bezbarwnej cieczy różni się od ilości i/lub typu tego synergetyka w kolorowym tuszu do drukarki strumieniowej.
- 17Drukarka strumieniowa, znamienna tym, że zawiera zestaw tuszów według któregokolwiek z zastrz. 11-16.
- 18Drukarka strumieniowa według zastrz. 17, znamienna tym, że objętość kolorowego tuszu jest mniejsza niż bezbarwnej cieczy.
- 19Kombinacja drukarki strumieniowej według zastrz. 17 albo 18 oraz elementów do oszacowania lub pomiaru właściwości dotyczących jakości drukowania.
- 20Kombinacja według zastrz. 19, w której elementy do oszacowania lub pomiaru właściwości dotyczących jakości drukowania są umieszczone w drukarce strumieniowej. Agfa Graphics N.V. Pełnomocnik:
Independent claims20
573 paragraphs in 3 sections, as filed
Technical field The present invention relates to inkjet printing methods and inkjet ink sets in which the inks are sprayed onto various types of ink receiving materials.
Background of the Invention [0002] In inkjet printing, tiny droplets of liquid ink are applied directly to the surface of the ink-receiving material, without physical contact between the printing device and the ink-receiving material. The printing device stores printed data electronically in memory and controls the mechanism of ejecting droplets in a visual way. Printing is performed by moving the print head across the ink-receiving material or vice versa, or by simultaneously moving the print head and the material.
[0003] When spraying inkjet ink on an ink-receiving material, the ink typically contains a liquid excipient and one or more solids such as dyes or pigments and polymeric binders. It will be understood that the optimal composition of such an ink depends on the printing method used and the properties of the ink-receiving material to be printed. Ink compositions can generally be divided into:
- water-based, the drying mechanism of which includes absorption, penetration and evaporation;
- solvent-based, the drying of which essentially involves evaporation;
- based on oil, whose drying involves absorption and penetration;
- fusible or phase-transition in which the ink is liquid at the spray temperature but solid at room temperature and in which drying is replaced by solidification; and that the first three types suitable for the resort
- UV curable, in which drying is replaced by polymerization.
[0004] It should be obvious, the ink compositions are more host, which is more or less absorbent, while hot melt and UV curable inks are typically used for printing on non-absorbing ink receiving materials.
[0005] However, it has been found that the behavior and action of the UV curable ink on a substantially non-absorbing ink receiving material is quite complicated compared to water-based inks on absorbing ink receiving materials. In particular, good and controlled distribution of the ink on the ink-receiving material has proved to be problematic and adhesion problems have sometimes been observed using different types of non-absorbing ink-receiving materials. The same problems were observed when solvent-based inkjet inks containing a binder were sprayed on various types of non-absorbing ink-receiving materials.
[0006] One approach to these problems is to develop and use different sets of inks for different types of substrate materials, but this is not the preferred solution, because changing the inks in the printer and the printhead is very time consuming and indeed unrealistic for the industrial printing environment. So, the general approach is to modify the surface chemical properties of the ink-receiving material using a suitable surface coating layer or pre-treatment, such as plasma or corona treatment.
[0007] Corona discharge treatment and plasma treatment increase the cost, complexity and maintenance of equipment used to process substrate materials. Substrate materials may contain serious impurities or substrates. IN
WO 2006/111707 irregularities that may interfere with the treatment of the substrate material and therefore do not lead to homogeneous spreading and adhesion of the ink.
[0008] Another possibility is to use the same set of inkjet inks for different ink-receiving materials by applying a surface layer prior to spraying, which also increases the complexity of the inkjet printer. In general, the surface layer is applied and dried or cured before spraying the inkjet ink such as e.g. in the inkjet printing process described in EP 1671805 A (AGFA) and in US Patent No. Ser. No. US 2003021961 (3M), but the surface layer may also remain moist, uncured as in International Patent Application WO 00/30856 (XAAR).
[0009] However, one surface layer composition suitable for all various materials is not available in the international patent application
SUN CHEMICAL) discloses an inkjet printing process in which: i) a primer is applied to the substrate material; ii) the ink is jetted onto the subcoated substrate; iii) the characteristics of the print quality are assessed; iv) the primer composition is adjusted depending on the estimated characteristics of the print quality; v) the regulated primer composition is applied to the substrate material and the ink is jet-applied to the substrate material with the primer coating to produce a printed product. Surface layers significantly increase the thickness of the ink layer, which can lead to different appearance and behavior, and a reduction in the flexibility of the ink layer.
[0010] Inkjet printing methods in which inkjet inks are mixed with colorless liquids or other color inks just prior to spraying were also investigated.
[0011] In US Patent No. Ser. US 6550892 (KODAK) discloses a drop-on-demand inkjet printing system for supplying droplets of selectable color ink to the receiving material by mixing colorless liquid ink with liquid inks of varying color and providing an ink mixture to the ejection chamber of the printhead. Also in the patent description Ser. US 6050680 (CANON) describes an ink jet printing device that can record images of densities for a first ink by using a plurality of different inks by mixing with a second ink in the description (LAITRAM) of colored tinted ink. the tonal range of each dye containing the dye not containing the dye. In the patent description Ser. US 6464336 (KODAK) discloses a drop-on-demand inkjet printing system in which the mixture is formed of a color inkjet ink, a colorless ink and a bleaching agent.
[0012] Instead of mixing colored inks, U.S. Patent Ser. US Patent No. 4,614,953 discloses a jet printing mechanism utilizing a single ink jet by injecting solid dyes into a liquid carrier to form a mechanism that allows a wider coloration due to the ability to pre-mix than is possible using spreading techniques using three color inks. [0013] All these inkjet printing methods relate to increasing the color gamut by spraying a colored ink diluted with different amounts of a colorless liquid, but they say nothing about producing ink mixtures for printing on different ink-receiving materials. [0014] It is desirable to be able to print with inkjet inks with consistent image quality on a wide variety of ink-receiving materials using a state of the art jet printer without the need for any complex and costly printer adaptation.
Objects of the invention [0015] Printing on a wide variety of ink-receiving materials, including non-absorbing substrate materials, such as glass, metal or polymer surfaces, often provides conflicting image quality and / or ink adhesion problems to ink-receiving materials. Changing the substrate material often causes the inconvenient change of inkjet ink sets, the use of a second inkjet printer, or some pretreatment of the substrate material that are not desired due to production capacity.
[0016] The object of the invention is to develop inkjet ink sets and inkjet printing methods that are capable of handling many different types of substrate materials using a prior art inkjet printer without compromising image quality integrity, physical properties such as image adhesion to base material and production capacity.
[0017] Further objects of the invention will become apparent from the description below.
Summary of the Invention [0018] Optimizing image quality or physical properties by mixing inkjet inks with a colorless liquid just prior to spraying causes changes in dye concentration, leading to differences in color gamut and image quality when time-consuming adaptations to color control are not performed streaming printer.
[0019] It was found that it was possible to obtain consistent image quality and improved physical properties on various ink-receiving materials by printing using a mixture of color inkjet inks and two or more colorless liquids in a fixed ratio in which the mixture of colorless liquids was changed depending on ink-receiving material.
[0020] The objects of the invention are realized using an inkjet printing method comprising the following steps in which:
(a) at least two or more colorless liquids having different compositions are provided to the inkjet printer, and at least one color inkjet ink;
b) mixing said colored inkjet ink in a controlled amount with said two or more colorless liquids; and
c) printing with an ink mixture comprising said color inkjet ink and two or more colorless liquids using an inkjet printer on the ink receiving material; wherein the at least one color inkjet ink contains at least one dye and said dye is a pigment.
[0021] The objects of the invention are also achieved using a color inkjet ink set comprising two or more colorless liquids having different compositions and a color inkjet ink wherein the at least one color inkjet ink contains at least one dye and said dye is a pigment
Advantageous effects [0022] It has also been found that it is possible to improve the durability of a colored inkjet ink by dispersing two or more less compatible compounds into a color inkjet ink and / or two or more colorless liquids. Eg. in radiation curable inks, the photoinitiator may be contained in the color inkjet ink, while the polymerization synergist and inhibitor are included in two or more colorless liquids. In this way, irradiation-curable irradiation inks having a higher cure speed can be obtained.
[0023] Another advantage is that the viscosity of the inkjet ink can not only be controlled using the print head spray temperature, but also by using a first colorless liquid with higher viscosity and a second colorless liquid with lower viscosity.
[0024] The mere application of an ink droplet to various substrates on which a single inkjet ink can give large differences in the size of the dots can be obtained by mixing colored inkjet ink with controlled amounts of a first colorless liquid that contains no surfactants or essentially does not contain surfactants and a second colorless liquid containing high concentrations of one or more surfactants.
[0025] Mixing a color inkjet ink and two or more colorless liquids can advantageously be used for many purposes that can relate to:
- image quality such as dot size, gloss, line quality and color blur;
- physical properties of the ink, such as viscosity, temperature, shelf life, surface tension, drying time, curing speed, adhesion to the substrate material, elasticity and hardness of the ink layer; and
- the spray atomization characteristics of the printer, e.g., delayed operation, accumulation of liquid on the nozzle plate, nozzle damage, droplet formation and satellite formation.
[0026] Differences in gloss between the inkjet inks of the substrate material usually lead to poor image quality. By adding the mixture in the correct ratio of two or more colorless liquids exhibiting different gloss levels, the gloss of the inkjet ink mixture can be matched to the gloss of a specific substrate material, resulting in improved image quality. For a second substrate material with a different gloss value, a different ratio of two or more colorless liquids having different gloss values is then selected.
[0027] Mixing of two or more colorless liquids with colored ink just prior to spraying can also be advantageously used to introduce security properties to secure documents. Typically, a colorless liquid containing a fluorescent compound, a phosphorescent compound, a thermochromatic compound, an iridescent compound or magnetic particles is additionally used in the ink mixture.
Brief Description of the Drawings [0028] Fig. 1 is a schematic view of an ink supply system for an inkjet printhead through a conduit to which the first colorless liquid "LIQ-1" is fed, followed by the second colorless liquid "LIQ-2" in a controlled amount.
[0029] Fig. 2 is a schematic view of the ink supply system for an inkjet printhead through a conduit into which a mixture of the first colorless liquid "LIQ-1" and the second colorless liquid "LIQ-2" in a controlled amount is fed. [0030] FIG. 3 is a schematic view of a system for supplying controlled amounts of ink, the first colorless liquid "LIQ-1" and the second colorless liquid "LIQ-2" to the ink mixing chamber, which then supplies the diluted ink to the printhead of the inkjet printer.
[0031] Fig. 4 is a schematic view of an ink supply system for an inkjet printhead through a conduit in which a mixture of the first colorless liquid "LIQ-1" and the second colorless liquid "LIQ-2" is mixed in the mixing chamber before being introduced into controlled amount to the ink in the cable. [0032] In Fig. 5 is a schematic view of a system for supplying controlled amounts of ink, a first colorless "LIQ-1" fluid to the printing chamber, and a second colorless "LIQ-2" mixing fluid (not shown) disposed in an inkjet printer head.
Definitions [0033] The term "inkjet ink set" as used in disclosing the present invention refers to an inkjet ink set that is incorporated into inkjet printers. This kit may, e.g., be made from a commercially available CMYK inkjet ink set with which at least two colorless liquids from other market sources are combined.
[0034] The term "coloring agent" used in disclosing the invention includes dyes and pigments.
[0035] The term "dye" as used in disclosing the present invention means a dye with a solubility of 10 mg / L or more in the medium in which the dye is used and under typical ambient conditions.
[0036] The term "pigment" is defined in DIN 55943, incorporated herein by reference, as a coloring agent which is practically insoluble in the medium used under typical ambient conditions and thus has a solubility of less than 10 mg / l in this medium.
[0037] The term "CI" is used in disclosing the present application as an abbreviation for Color Index.
[0038] The term "UV" is used in disclosing the present invention as an abbreviation for ultraviolet radiation.
[0039] The term "ultraviolet radiation" as used in disclosing the present invention includes electromagnetic radiation in the wavelength range from 100 to 400 nanometers.
[0040] Unless otherwise specified, the term "wt%" is used in disclosing the present invention as a wt% based on the total weight of the ink.
[0041] The term "actinic radiation" as used in disclosing the present invention includes reaction initiation radiation used in which it produces electromagnetic photochemical capable.
[0042] The term "Norrish type I initiator" of the disclosure of the invention means the initiator, after fission, directly from the initiating radical.
[0043] The term "Norrish type II initiator" as used in disclosing the present invention, means an initiator that, in the excited state, forms free radicals by removing hydrogen or extracting an electron from a second compound that actually becomes an initiating free radical. The second compound is called a polymerization co-initiator or synergist. Synergists are compounds having a carbon atom with at least one hydrogen atom in the α position to a nitrogen atom.
[0044] The term "photo-acid generator" as used in disclosing the present invention means an initiator that produces an acid or hemiacid upon exposure to actinic radiation. The photo-acid generator is often also called a cationic initiator.
[0045] The term "thermal initiator" as used in disclosing the present invention means an initiator that produces initiating substances upon exposure to heat.
[0046] As used herein, the term "alkyl" includes all variants possible for each number of carbon atoms in the alkyl group, such as for three carbon atoms: n-propyl and isopropyl; for four carbon atoms: n-butyl, isobutyl and tertiary butyl; for five carbon atoms: n-pentyl, 1,1-dimethylpropyl, 2,2-dimethylpropyl and 2-methylbutyl, etc.
Methods of inkjet printing and ink sets [0047] The inkjet ink method according to the invention comprises successive steps in which:
(a) at least two or more colorless liquids having different compositions are provided to the inkjet printer, and at least one color inkjet ink;
b) mixing said colored inkjet ink in a controlled amount with said two or more colorless liquids; and
c) printing with an ink mixture comprising said color inkjet ink and two or more colorless liquids using an inkjet printer on the ink receiving material.
[0048] Although the possibilities of adapting the ink mixture to a specific ink-receiving material increase with the number of colorless liquids present in the ink set, many problems regarding consistent image quality and adhesion on different substrate materials can already be solved by applying 2, 3, 4, 5 or colorless liquids. In a preferred embodiment, the inkjet ink set contains three colorless liquids for handling quite different substrate materials.
[0049] For color printing, the inkjet ink set includes at least three color inkjet inks and preferably also a black inkjet ink. Typically, three color inkjet inks are cyan ink, fuchsin ink, and yellow ink. Red, green, and blue inks are also sometimes used as an inkjet ink set or are added to a CMYK inkjet ink set. The inkjet ink set according to the invention should then contain at least two or more colorless liquids. Two or more colorless liquids are preferably used to dilute all colored inks and possibly black inks using the same mixture of colorless liquids. Because of this, the consumption of colorless liquids is often greater than the consumption of colorless inks. To reduce the frequency of adding additional amounts of colorless liquids or replacing cartridges with a colorless liquid, the volume of the colorless liquid in the inkjet ink set or in the inkjet printer is preferably greater than the volume of the color ink. Preferably the volume of colorless liquid is at least 25%, more preferably at least 50% and most preferably at least 100% greater than the volume of colored ink.
[0050] In a preferred embodiment, the controlled amount with which the color inkjet ink and two or more colorless liquids are mixed relates to a fixed ratio of the weight percentage of the color inkjet ink to the weight percentage of two or more colorless liquids. The ratio of the percentage by weight of the color inkjet ink to the percentage by weight of two or more colorless liquids is preferably between 9: 1 and 2: 3, more preferably between 8: 2 and 1: 1. For a ratio greater than 9: 1, the amount of colorless liquids is often not large enough to give the ink mixture improved properties. For example, improving the adhesion of ink to an radiation curable inkjet printer generally requires the use of at least 25% by weight of another type of monomer. On the other hand, for a ratio of less than 2: 3, the impact of the mixing error on the image quality becomes significant. [0051] In another embodiment, the printer can be set to 2 or 3 "fixed ratios" with color management for each
Depending on the ratio, the printer can then be switched from one color management to another. This can be useful, e.g. if for a specific task for a printer the color gamut is more important and the only property to improve is the dot size, then a larger fixed ratio can be chosen by increasing the surfactant concentration in one of the colorless liquids. An important issue is the use of controlled amounts of colorless liquids in the selected ratio with the corresponding color management on site.
pre-determined relationship.
[0052] The inkjet printing method uses a so-called "multi-density" inkjet ink set comprising colored inkjet inks of the same color but with different color intensities. For example, a set of color inkjet ink cartridges "dark inkjet" light inkjet printer ink other preferred ink may contain fuchsin "and fuchsin". In the solution, the high intensity inkjet ink set includes dark and light inkjet inks for colors such as fuchsin and cyan. Dark and light black inks may also be included in the color inkjet ink set.
[0053] A preferred solution includes printing using a color inkjet ink diluted with a controlled liquid that does not contain an amount of the first colorless or substantially no surfactants and a second colorless liquid containing a high concentration of one or more surfactants. In this way, the same distribution and dot size of the ink droplets can be obtained on a variety of ink-receiving materials.
[0054] Another preferred solution includes printing using a color inkjet ink diluted with controlled amounts of colorless liquids capable of improving adhesive properties. The adhesion can be modified using various polymerizable compounds, surfactants, binders and / or organic solvents. If a color ink set contains only one color inkjet ink and does not contain colorless liquids, a compromise should be sought to obtain acceptable adhesion on several ink-receiving materials by creating a complex mixture of ingredients, which often has a negative effect on the dispersion durability of a colored inkjet ink .
[0055] For example, it is known that the adhesion of inks cured by irradiation on polyvinyl chloride substrates is promoted by the use of one or more monomers that are suitable for swelling a PVC substrate, and which are selected from the group consisting of tetrahydrofurfuryl acrylate, 1,6-hexanediol diacrylate and N-vinylcaprolactam. However, adhesion on polycarbonate substrates is promoted by the use of one or more monomers that are suitable for swelling with a polycarbonate substrate and which are selected from the group consisting of propoxylated neopentyl glycol diacrylate, 2-phenoxyethyl acrylate, 2- (2-ethoxyethoxy) ethyl acrylate and diacrylate polyethylene glycol. In the case of irradiation cure printing method, it is not necessary to produce the "best possible" monomer mixture suitable for swelling a polyvinyl chloride substrate or a polycarbonate substrate. Instead, a dedicated monomer mixture, consisting predominantly of monomers, can be prepared, e.g. for swelling a polyvinyl chloride substrate, if the substrate is fed to the printer.
Inkjet Printer & Ink Supply Systems [0056] Industrial inkjet printers generally include an ink supply system for feeding ink to an inkjet printhead. The jet printheads produce droplets continuously or on demand. "Continuously" means that a continuous stream of ink droplets are created, e.g., by forcing ink delivery. Manufacturing droplets "on demand" differs from "continuous" in that the ink droplets are only ejected from the printhead by manipulating the physical process to temporarily overcome surface tension forces that hold the ink in the printhead. The ink is held in the nozzle to form a meniscus. The ink stays in place until another force overcomes the surface tension forces that are inherent in the liquid. The most common practice is to suddenly increase the pressure on the ink, pushing the ink out of the nozzle. One category of physical phenomena used by drop-on-demand jet printheads is electrostriction, a change in transducer dimension in response to an applied electric field. Electrostriction is the strongest in piezoelectric materials, and therefore the above printheads refer to piezoelectric printheads. A very small change in the dimensions of the piezoelectric material is used over a large area to obtain a volume change that is large enough to squeeze a drop of ink from the small chamber. The piezoelectric print head contains a plethora of small ink chambers arranged in series, each containing a separate nozzle and a percentage of the convertible wall surface to create the volume changes required to push ink droplets out of the nozzle, according to electrostriction principles.
[0057] Preferably, the inkjet printer is a drop-on-demand inkjet printing system comprising piezoelectric printheads for delivering droplets of a selectable color ink mixture to the ink receiving material.
[0058] The inkjet ink is fed to the printhead ink ejection chambers by an ink supply system that first conditions the ink to achieve an even operation of the inkjet printhead. Conditioning includes, e.g., degassing the ink and regulating the back pressure at the nozzle.
[0059] It is known that the presence of air bubbles in the ink chamber of a piezoelectric printhead often causes operational damage to the printhead. If air is present in the ink chamber, the intended pressure changes resulting from the piezoelectric deformation of part of the ink chamber walls will be absorbed by the air, leaving the ink pressure unchanged. The surface tension forces of the ink in the nozzle maintain the meniscus and no drops will be ejected from the ink chamber. At the frequencies at which piezoelectric transducers in the piezoelectric printhead operate, i.e. in the range from kHz to MHz, not only air bubbles but also dissolved air in the ink may cause operational damage as described above. In the art, concepts have been disclosed to avoid the presence of air bubbles in the ink chamber by creating an air trap above the ink chamber, i.e. before the ink enters the ink chamber. In EP 714779 A (CANON) and in US Patent No. Ser. US Patent No. 4,929,63 (HP) proposed solutions in the form of air buffers or gas separators that allow air bubbles to rise and remove them from the ink in the intermediate tank before supplying the ink to the printhead.
[0060] A second important point in the ink supply system is the pressure at the nozzle, which is fundamental to the control and proper functioning of the printhead.
Jet printheads work best at slightly negative nozzle pressure or back pressure. In practice, this is often achieved by maintaining a height difference between the surface of the free ink in the deaerated ink supply tank and the meniscus in the nozzle. Ie, the surface of the free ink in the vented delivery tank is kept gravimetrically a few centimeters below the level of the meniscus in the nozzle. This height difference sets the hydrostatic pressure difference to regulate the back pressure at the nozzle. In reciprocating printhead configurations, the ink supply tank is off-axis, i.e., in a non-scanning position, since lowering the position of the ink supply tank depending on the printhead may interfere with the transfer of the printing medium. Flexible tubes are used to connect the off-axis ink supply tank to the on-axis print head, as disclosed, e.g., in US Pat. Ser. U.S. Patent No. 4,929,633 (HP). During the increase in speed and delay of the printhead, pressure waves are created in the tubes that can seriously disturb the pressure balance at the meniscus and can lead to nozzle leakage in the event of a negative pressure drop, or meniscus collapse in the event of an increase in negative pressure and air suction into the ink hose. . Many approaches have been proposed for regulating back pressure when using reciprocating printheads.
regulate back pressure in the form
Buffer mechanisms and above 1G, insufficient time. IN
EP 1142713 A (SEIKO pressure dampers mounted together with the print head on a reciprocating carriage, is disclosed in EP 1120257 A (SEIKO EPSON) and in US Patent No. 6,485,137 (APRION DIGITAL). responses to these European EPSON description) describes a vented subtlete
The device carriage delay subset is a patent application it serves as a local ink tank near the print head and is filled periodically from the main tank located off the axis. This solution provides better regulation of the nozzle back pressure by maintaining a local hydrostatic pressure difference between the surface of the free ink in the vented subtank and the meniscus.
Ink Mixing Elements [0061] There are no real restrictions on the choice of components for mixing colored ink and colorless liquids, as long as they are made of materials compatible with the inks, e.g., solvent resistant materials, when the solvent inkjet inks are to be mixed, and how much thorough mixing of colored ink and colorless liquids is obtained. The dilution of concentrated color inkjet ink with one or more colorless liquids should be carefully controlled to avoid changing dye concentrations in the ink causing discontinuous image quality.
[0062] In a preferred embodiment, the selected ink mixing means are capable of mixing concentrated colored inkjet ink and variable controlled amounts of two or more colorless liquids, in a predetermined ratio of content by weight percentage of colored inkjet ink to content by weight percentage two or more colorless liquids.
[0063] The amounts of concentrated color inkjet ink and two or more colorless liquids that are mixed can be selected accordingly. Preferably, more of the concentrated color inkjet ink will be diluted with smaller amounts of one or more colorless liquids. Eg. the diluted, radiation curable color inkjet ink may contain 60% by weight of concentrated color inkjet ink and 40% by weight of two or more colorless liquids, depending on the type of ink-receiving material selected. In a more preferred embodiment, the diluted, radiation curable color inkjet ink contains 70% by weight of concentrated color inkjet ink and 30% by weight of two or more colorless liquids, depending on the type of ink-receiving material selected. In another preferred embodiment, the diluted, radiation curable color inkjet ink contains 80% by weight of concentrated color inkjet ink and 20% by weight of two or more colorless liquids, depending on the type of ink-receiving material selected.
[0064] Color ink and colorless liquids can be mixed at different locations of the inkjet printer, e.g. directly at the first connection of the inkjet inks and colorless liquids with the inkjet printer, near the inkjet printheads or even inside the printheads. The smaller the distance between the ink mixing location and the souls of the printhead, the less ink is spilled to adapt to the new ink-receiving material to be printed.
[0065] In one preferred embodiment, the ink mixing elements have a compact design so that they can be introduced into a carriage containing a set of printheads that moves back and forth along the fast scan direction.
[0066] Preferably, the ink mixing elements are selected such that they do not introduce air bubbles into the ink mixture.
[0067] For certain inkjet inks, such as dye inks, the ink mixing elements may simply consist of wires connecting into a single wire that performs a number of sharp turns or V-shaped turns to mix inks and colorless liquids .
[0068] More complex ink mixing means may include pumps, valves, mixing chambers, etc.
[0069] If necessary, mixing of the mascara can be done by cooling to prevent heat accumulation. For radiation cured inkjet inks, mixing of the ink is carried out as much as possible under lighting conditions in which actinic radiation has been substantially disabled.
[0070] In one embodiment, the colored ink and colorless liquids are fed to the inkjet print head via a conduit in which the ink mixture is generated in-situ in the conduit. The flow regulator is adapted to selectively measure the amount of colorless liquids from colorless liquid sources to a conduit running from the source of the color inkjet ink to the push chambers of the printhead. The ink supply systems of this embodiment are exemplified in Figs. 1 and 2. [0071] In another embodiment, the ink supply system includes an ink mixing chamber in which colored ink and colorless liquids are first mixed in a controlled amount prior to delivery this printhead ink mixture. The ink supply system of this embodiment is exemplified in Figure 3.
[0072] The two previous solutions may also be combined to form an ink supply system in which colorless liquids are first mixed in a controlled amount in an ink mixing chamber and then mixed in-situ with the color inkjet ink in the conduit between the color ink source for the printer streaming and printhead. The ink supply system of this embodiment is exemplified in Figure 4.
[0073] In another embodiment, mixing in a controlled amount of colored ink and colorless liquids occurs within the printhead. The ink supply system of this embodiment is exemplified in Figure 5.
[0074] Although it is possible to position (parts) of the ink mixing system inside the printhead, the ink mixing system is preferably separated from the printhead. This enables the ink supply system to be connected to a wide variety of printheads and inkjet printers already available on the market, and thus does not increase the complexity and cost of developing printheads. In addition, maintenance is much easier with an ink mixing system that is not placed inside the print head in case where, for example, flocculation of the inks may occur.
[0075] It should be evident that for an ink set, mixing elements are preferably present for each color inkjet ink in the inkjet ink set.
Computing Elements [0076] In a preferred embodiment, the ink supply system is connected to a computer to control the ink mixing process. Control may include opening and closing the valves, controlling the flow through the pumps, rotation speed of the agitator, and other mechanical settings to obtain the desired ink mixture. However, the computer is preferably also used to store and recall data on ink mixtures used on specific ink-receiving materials. This enables the inkjet printer to be quickly adapted to the specific ink-receiving material that has already been printed in the past with the same inkjet ink set.
[0077] In another embodiment, the computer may be used to create a test image of various ink mixtures on previously unused ink-receiving material, which after examination of the printed pattern allows selection of an ink mixture showing desired image quality, adhesion, etc. properties. Using this method each time a new substrate material is used as the ink-receiving material, a (digital) library of ink mixing data is obtained for the individual ink-receiving materials. Such ink mixing data include the ratio of color inkjet ink to colorless liquids, the type and amount of each colorless liquid used, and their relationship to image quality and physical properties. The use of a library, more preferably a digital library, leads to increased production capacity.
[0078] For a number of characteristic properties, it is possible to automate the estimation of a test image of various ink mixtures by introducing, in a subsequent printer, elements capable of measuring or part of estimating line widths, mottling, print density, and coloring.
straight edge shape, gloss and / or intensity
Inkjet Ink Receiving Materials [0079] The ink receiving material suitable for the inkjet printing method according to the invention is not limited to any particular type and may be transparent, translucent or opaque.
The ink-receiving material may be colored or metallized. It can be a temporary substrate, e.g. for transferring an image to another substrate after printing. Applications such as 3D printing and direct printing on wooden doors or panels and ceramics are also within the scope of the invention.
[0080] Aqueous inks are generally printed on absorbent ink-receiving materials. Ancillary inkjet inks, solvent based prevention and radiation curing inks can also be printed on ink-receiving materials that generally do not absorb aqueous solution. For example, standard paper is an absorbent material that receives ink. On the other hand, resin-coated paper, e.g. polyethylene coated paper or polypropylene coated paper is essentially substantially non-absorbent.
[0081] The ink-receiving material may comprise a carrier with at least one ink-receiving layer. The ink-receiving layer may consist of only one single layer, or alternatively may consist of two, three or more layers. The ink-receiving layer may contain one or more polymeric binders and optionally fillers. The ink-receiving layer and an optional layer such as a backing layer for curling and / or for adhesive purposes may then contain well known conventional ingredients such as coating agents, cationic surfactants serving as crosslinking agents, plasticizers, acting as mortar, stabilizers for exposure to light, pH adjusting agents, antistatic agents, biocides, wetting agents, bleaching agents and matting agents.
[0082] The ink-receiving layer and optional sub-layer (sub-layers) can be crosslinked to some extent to produce such desirable characteristics as water resistance and anti-clogging properties. Cross-linking is also useful for providing abrasion resistance and resistance to fingerprinting on an item as a result of handling it.
[0083] Carriers suitable for ink receiving layers are also suitable ink receiving materials for solvent based inkjet or ink cured inks and include polymeric substrate materials such as cellulose acetate and propionate, cellulose acetate and butyrate, polyesters, such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN); oriented polystyrene (OPS); oriented nylon (ONs); polypropylene (PP), oriented polypropylene (OPP); poly (vinyl chloride) (PVC); and various polyamides, polycarbonates, polyimides, polyolefins, poly (vinylacetals), polyethers and polysulfonamides, opaque white polyesters and extruded blends of polyethylene terephthalate and polypropylene. Acrylic resins, phenolic resins, glass and metals can also be used as ink-receiving material. Other suitable ink-receiving materials can be found in Modern Approaches to Wettability: Theory and Applications. Editors of SCHRADER, Malcolm E. et al., New York: Plenum Press, 1992. ISBN 0306439859.
[0084] The ink-receiving material may also contain mineral particles as fillers, such as CaCO containing PET<sub>3</sub>, PET containing TiO<sub>2</sub>, Amorphous PET (APET) and glycolyzed PET (PETG).
[0085] The ink-receiving material may be provided with a self-adhesive back layer. Examples of self-adhesive materials receiving PVC ink include MPI ™ vinyls from AVERY-DENNISON, Digital ™ vinyls from METAMARK, Digital Multi-fix ™ white vinyls from MULTI-FIX and Grafiprint ™ vinyls from GRAFITYP.
[0086] Polyester film backing materials and especially polyethylene terephthalate are preferred for certain applications, especially types having excellent dimensional stability. When such a polyester is used as an ink-receiving material, a substitute layer may be used to improve the bonding of the sprayed ink layer to the substrate material in the case where the ink forms a substantially non-absorbing ink-receiving material together with the uncovered substrate material. Suitable replacement layers are well known in the art of photography and include, for example, vinylidene chloride polymers such as vinylidene chloride / acrylonitrile / acrylic acid terpolymers or vinylidene chloride / methyl acrylate / itaconic acid terpolymers. Stabilizers, corrective additives, matting agents, agents that regulate the physical properties of the film, such as waxes, can also be added to the replacement layer, if required.
[0087] The ink-receiving material may also be made of an inorganic material such as metal oxide or a metal (e.g., aluminum and steel).
[0088] Other suitable ink-receiving materials may be selected from such as cardboard, wood, composite panels, coated plastics, tarpaulin, textiles, glasses, plant fiber products, leather, magnetic materials and ceramics.
Inkjet ink sets [0089] The inkjet ink set according to the invention comprises at least one color inkjet ink and at least two or more colorless liquids in which two or more colorless liquids have different compositions.
[0090] In a most preferred embodiment, the ink set contains cyan, fuchsin, yellow and black inkjet ink.
[0091] In another embodiment, the inkjet printing method uses a so-called "multi-density" inkjet ink set comprising colored inkjet inks having the same color but different color intensities. For example, a set of color inkjet inks may include "dark fuchsin" inkjet ink and "light fuchsin" inkjet ink. In another preferred embodiment, the high intensity inkjet ink set includes dark and light inkjet inks for colors such as fuchsin and cyan. Dark and light black inks may also be included in the color inkjet ink set. Other colored inks such as green, red, blue, orange and white ink may also form part of the inkjet ink set.
[0092] In one embodiment, the inkjet ink set contains the amount and / or type of polymerizable compound in a colorless liquid that differ from the amount and / or type of the polymerizable compound in the color inkjet ink.
[0093] In another embodiment, the inkjet ink set includes the amount and / or type of surfactant in a colorless liquid that differ from the amount and / or type of surfactant in a color inkjet ink.
[0094] In another embodiment, the inkjet ink set includes the amount and / or type of initiator in a colorless liquid that differ from the amount and / or type of initiator in the color inkjet ink.
[0095] In another embodiment, the inkjet ink set contains the amount and / or type of polymerization synergist in a colorless liquid that differ from the amount and / or type of polymerization synergist in a color inkjet ink.
[0096] In a preferred embodiment, the inkjet ink set includes solvent based inkjet inks.
[0097] In another preferred embodiment, the inkjet ink set comprises radiation-curable inks for an inkjet printer. In another preferred embodiment of the irradiation inkjet ink set, the photoinitiator is present in the color inkjet ink and not in colorless liquids or vice versa. In another additional preferred embodiment, the polymerization synergist is present in the color inkjet ink and not in colorless liquids or vice versa.
Color inkjet inks [0098] The inkjet inks in an ink set according to the invention are preferably non-aqueous inkjet inks. In a non-aqueous inkjet ink, the ingredients are present in a dispersion medium which is a non-aqueous liquid at the spray temperature. [0099] The term "non-aqueous liquid" refers to a liquid carrier that should not contain water. However, it can sometimes contain a small amount, generally less than 5% by weight of water based on the total weight of the ink. This water was not intentionally added to the ink, but appeared in the formulation together with other ingredients as its impurity, such as, for example, polar organic solvents. Amounts of water greater than 5% by weight tend to cause instability of the non-aqueous inkjet inks, preferably the water content is below 1% by weight based on the total weight of the dispersion medium, and most preferably these mediums contain no water at all.
[0100] The inkjet inks in an inkjet ink set according to the invention preferably contain pigment as a dye. If the dye is not a self-dispersing pigment, the inkjet inks preferably also contain a dispersant, more preferably a polymeric dispersant.
[0101] The inkjet ink set according to the invention may further also contain at least one surfactant.
[0102] The inkjet inks of an ink set according to the invention may contain at least one humectant to prevent nozzle clogging due to its ability to reduce the ink evaporation rate.
[0103] The pigmented color inkjet inks of the present invention may contain at least one dispersion synergist. A mixture of dispersion synergists can be used to further improve dispersion stability.
[0104] The inkjet inks according to the invention are preferably inkjet inks selected from the group consisting of an organic solvent based ink, an oil based ink and a curable inkjet ink. The curable inkjet ink is preferably radiation curable.
[0105] The viscosity of the inkjet ink is preferably less than 100 mPa.s at 30 ° C and a shear rate of 100 s<sup>-1</sup>. The viscosity of the inkjet ink is preferably less than 30 mPa.s, more preferably lower than 15 mPa.s and most preferably between 2 and 10 mPa.s at a shear rate of 100 s<sup>-1</sup> and a spray temperature of 10 to 70 ° C.
[0106] The curable inkjet ink may contain as dispersion medium monomers, oligomers and / or prepolymers having different degrees of functionality. A mixture including combinations of mono-, di-, trii / or higher functionality monomers, oligomers or prepolymers may be used. A catalyst called an initiator that initiates the polymerization reaction may be contained in the curable inkjet ink. The initiator may be a thermal initiator, but is preferably a photoinitiator. The photoinitiator needs less energy to activate monomers, oligomers and / or prepolymers to produce the polymer. A photoinitiator suitable for use in the curable pigment dispersion may be an initiator
Norrish type I, Norrish type II initiator or photo-acid generator.
[0106] The curable inkjet inks of an ink set according to the invention may further also contain at least one inhibitor.
[0107] The CMYK inkjet ink set can also be extended with one or more additional inks such as red, green, blue and orange inks to further enlarge the color gamut of the image. The CMYK ink set can also be extended with a combination of full density and light density inks of color inks and / or black inks to improve image quality by reducing graininess.
Dyes [0109] Color inkjet inks from an inkjet ink set according to the invention contain at least one dye. The dyes used in the inkjet inks may be pigments, dyes or a combination thereof. Organic and / or inorganic pigments can be used.
[0110] The radiation curable inks for an inkjet printer or solvent based inks for an inkjet printer preferably contain pigments as dyes.
[0111] Pigments in inkjet inks may be black, white, cyan, fuchsin, yellow, red, orange, violet, blue, green, brown, they may be mixtures of such pigments, etc.
[0112] The color pigment may be selected from the pigments disclosed in HERBST, Willy et al., Industrial Organic Pigments, Production, Properties, Applications. 3rd edition. Wiley - VCH, 2004. ISBN 3527305769.
[0113] Particularly preferred pigments are CI Pigment Yellow 1, 3, 10, 12, 13, 14, 17, 55, 65, 73, 74, 75, 83, 93, 97, 109, 111, 120, 128, 138, 139, 150, 151, 154, 155, 180, 185 and 213.
[0114] Particularly preferred pigments are CI Pigment
Yellow 120, 151, 154, 175, 180, 181 and 194.
[0115] The most preferred yellow pigments are CI
Pigment Yellow 120, 139, 150 155 and 213.
[0116] Particularly preferred pigments are CI Pigment
<td>Red 17, 22</td><td> , 23,</td><td> 41,</td><td> 48:1,</td><td> 48:2</td><td> , 49:1, 49:2, 52:1, 57:1,</td>
<td> 81:1, 81:3, 88,</td><td> 112,</td><td> 122,</td><td> 144,</td><td> 146,</td><td> 149, 169, 170, 175, 176,</td>
<td> 184, 185, 188,</td><td> 202,</td><td> 206,</td><td> 207,</td><td> 210,</td><td> 216, 221, 248, 251, 254,</td>
255, 264, 270 and 272. For the production of decorative laminates, CI Pigment Red 254 and CI are most preferred
Pigment Red 266. For other applications of non-aqueous inkjet inks, the most preferred pigments are CI Pigment Red 122 and CI Pigment Purple 19.
[0117] Particularly preferred pigments are CI Pigment
Purple 1, 2, 19, 23, 32, 37 and 39.
[0118] Particularly preferred pigments are CI Pigment
Blue 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16, 56, 61 and (bridged) pigments containing aluminum phthalocyanines.
[0119] Particularly preferred pigments are CI Pigment Orange 5, 13, 16, 34, 40, 43, 59, 66, 67, 69, 71 and 73. [0120] Particularly preferred pigments are CI Pigment Green 7 and 36.
[0121] Particularly preferred pigments are CI Pigment Brown 6 and 7.
[0122] Suitable pigments include mixed crystals of the particularly preferred pigments listed above. For example, Cinquasia Magenta RT-355-D from Ciba Specialty Chemicals is commercially available.
[0123] Carbon black is preferred as a pigment for the black inkjet ink. Suitable black pigments include carbon blacks such as Pigment Black 7 (e.g. Carbon Black MA8® from MITSUBISHI CHEMICAL), Regal® 400R, Mogul® L, Elftex® 320 from CABOT Co., or Carbon Black FW18, Special Black 250, Special Black 350, Special Black 550, Printex® 25, Printex® 35, Printex® 55, Printex® 90, Printex® 150T from DEGUSSA. Additional examples of suitable pigments are disclosed in US Pat. Ser. No. 5,389,133 (XEROX).
[0124] It is also possible to make a mixture of pigments in color inkjet inks. For some applications, neutral black inkjet ink is preferred and can be obtained, e.g., by mixing black pigment and cyan pigment in the ink. The application of inkjet printing may also require one or more spot colors, e.g. for inkjet packaging or for textile inkjet printing. Silver and gold are often desirable colors for inkjet poster printing and point of sale display.
[0125] Also, inorganic pigments may be present in color inkjet inks. CI Pigment Metal 1, 2 and 3 are particularly preferred pigments. Illustrative examples of inorganic pigments include titanium oxide, barium sulfate, calcium carbonate, zinc oxide, lead sulfate, lead yellow, zinc yellow, red iron (III) oxide, cadmium red, ultramarine blue, Prussian blue, green chromium oxide, cobalt green, amber , titanium black and synthetic iron black.
[0126] Generally, pigments are stabilized in the dispersion medium by dispersing agents, such as polymeric dispersants or surfactants. However, the surface of the pigments can be modified to form so-called "self-dispersing" or "self-dispersible" pigments, i.e. pigments that disperse in the dispersion medium without dispersing agents.
[0127] The pigment particles in the inkjet ink should be small enough to allow free flow of the ink through the inkjet-printing device, especially at the ejecting nozzles. It is also desirable to use small particles to obtain maximum color intensity and to slow down sedimentation.
[0128] The numeric average pigment particle size is preferably from 0.050 to 1 pm, more preferably from 0.070 to 0.300 pm and particularly preferably from 0.080 to 0.200 pm. Most preferably, the numeric average pigment particle size is no larger than 0.150 pm. However, the average pigment particle size for white inkjet inks containing, e.g., the titanium dioxide pigment, is preferably between 0.100 and 0.300 μη.
[0129] The pigment is preferably used in the pigment dispersion used to make the inkjet inks in an amount of 10 to 40% by weight, preferably 15 to 30% by weight based on the total weight of the pigment dispersion. In the inkjet ink, the pigment is preferably used in an amount of from 0.1 to 20% by weight, preferably from 1 to 10% by weight based on the total weight of the inkjet ink.
[0130] Dyes suitable for the color inkjet inks in the ink set according to the invention include direct dyes, acid dyes, basic dyes and reactive dyes.
[0131] Suitable direct dyes for color inkjet inks include:
<td></td><td>- CI</td><td>Direct</td><td>Dye</td><td>Yellow 1,</td><td> 4,</td><td> 8, 11, 12, 24,</td>
<td> 26,</td><td> 27, 28,</td><td> 33, 39, 44,</td><td> 50, 58,</td><td> 85, 86,</td><td> 100</td><td> , 110, 120, 132,</td>
<td> 142,</td><td>and 144 - CI</td><td>Direct</td><td>Dye</td><td>Red</td><td> 1, 2</td><td> , 4, 9, 11, 134,</td>
<td> 17,</td><td> 20, 23,</td><td> 24, 28, 31,</td><td> 33, 37,</td><td> 39, 44,</td><td> 47,</td><td> 48, 51, 62, 63,</td>
<td> 75,</td><td> 79, 80,</td><td> 81, 83, 89,</td><td> 90, 94,</td><td colspan="2"> 95, 99, 220,</td><td>224, 227 and 343</td>
<td></td><td>- CI</td><td>Direct</td><td>Dye</td><td>Blue</td><td> 1,</td><td> 2, 6, 8, 15, 22,</td>
<td> 25,</td><td> 71, 76,</td><td> 78, 80, 86,</td><td> 87, 90,</td><td> 98, 106,</td><td> 108</td><td> , 120, 123, 163,</td>
<td> 165,</td><td colspan="2"> 192, 193, 194, 195</td><td colspan="2"> , 196, 199, 200,</td><td> 201</td><td> 202, 203, 207,</td>
<td> 236,</td><td>and 237 - CI</td><td>Direct</td><td>Dye</td><td>Black 2</td><td> , 3,</td><td> 7, 17, 19, 22,</td>
<td> 32,</td><td> 38, 51,</td><td> 56, 62, 71,</td><td> 74, 75,</td><td> 77, 105,</td><td> 108,</td><td>112, 117, 154 and</td>
195 [0132] Suitable acid dyes for color inkjet inks include:
<td></td><td>- CI Acid</td><td>Yellow Dye 2,</td><td> 3,</td><td> 7, 17, 19, 23, 25,</td>
<td> 20,</td><td> 38, 42, 49, 59,</td><td>61, 72, and 99</td><td></td><td></td>
<td></td><td>- CI Acid</td><td colspan="2">Orange Dye</td><td>56 and 64</td>
<td></td><td>- CI Acid</td><td>Red dye</td><td> 1,</td><td> 8, 14, 18, 26, 32,</td>
<td> 37,</td><td> 42, 52, 57, 72,</td><td colspan="2"> 74, 80, 87, 115, 119,</td><td> 131, 133, 134, 143,</td>
<td> 154,</td><td> 186, 249, 254,</td><td>and 256</td><td></td><td></td>
<td></td><td>- CI Acid</td><td>Violet dye</td><td> 11,</td><td>34, and 75</td>
<td></td><td>- CI Acid</td><td>Blue dye</td><td> 1,</td><td> 7, 9, 29, 87, 126,</td>
<td> 138,</td><td> 171, 175, 183,</td><td>234, 236, and 249</td><td></td><td></td>
<td></td><td>- CI Acid</td><td>Green Dye 9,</td><td> 12</td><td>, 19, 27, and 41</td>
<td></td><td>- CI Acid</td><td>Black 1 dye,</td><td> 2,</td><td> 7, 24, 26, 48, 52,</td>
<td> 58,</td><td> 60, 94, 107, 109</td><td>, 110, 119, 131, and</td><td colspan="2"> 155</td>
[0133] Suitable reactive dyes for color inkjet inks include:
- CI Reactive Yellow Dye 1, 2, 3, 14, 15, 17, 37, 42, 76, 95, 168, and 175
- CI Reactive Red Dye 2, 6, 11, 21, 22, 23, 24, 33, 45, 111, 112, 114, 180, 218, 226, 228, and 235
- CI Reactive Dye Blue 7, 14, 15, 18, 19, 21, 25, 38, 49, 72, 77, 176, 203, 220, 230, and 235
- CI Reactive Orange Dye 5, 12, 13, 35, and
- CI Reactive Brown Dye 7, 11, 33, 37, and 46 - CI Reactive Green Dye 8 and 19 - CI Reactive Purple Dye 2, 4, 6, 8, 21, 22, and
- CI Reactive Black 5, 8, 31, and 39 [0134] Suitable basic dyes for color inkjet inks include:
- CI Basic Yellow Dye 11, 14, 21, and 32
- CI Basic Red Dye 1, 2, 9, 12, and 13
- CI Basic Purple Dye 3, 7, and 14
- CI Basic Blue Dye 3, 9, 24, and 25 [0135] If the color inkjet ink contains water, the dyes may show an ideal coloration in the appropriate range of pH values. So, the inkjet ink preferably additionally contains a pH regulator.
[0136] Suitable pH adjusting agents include NaOH, KOH, NEt<sub>3</sub>, NH<sub>3</sub>, HCl, HNO<sub>3</sub>, H<sub>2</sub>SO<sub>4</sub> and (poly) alkanolamines such as triethanolamine and 2-amino-2-methyl-1-propanol. Preferred pH adjusting agents are NaOH and H<sub>2</sub>SO<sub>4</sub>.
[0137] Dyes are used in the color inkjet inks in an amount of from 0.1 to 30% by weight, preferably from 1 to 20% by weight based on the total weight of the inkjet ink.
[0138] In a specific embodiment, the dye is a fluorescent dye used to impart safety properties. Suitable examples of a fluorescent dye include Tinopal ™ classes such as Tinopal ™ SFD, Uvitex ™ classes such as Uvitex ™ NFW and Uvitex ™ OB, all available from CIBA SPECIALTY CHEMICALS; Leukophor ™ from CLARIANT and Blancophor ™ class, such as Blancophor ™ REU and Blancophor ™ BSU from BAYER.
Dispersants [0139] Typical polymeric dispersants are copolymers of two monomers, but may contain three, four, five or even more monomers. The properties of polymeric dispersants depend on both the properties of the monomers and their distribution in the polymer. Suitable copolymeric dispersants have the following polymer compositions:
- statistically polymerized monomers (e.g. monomers A and B polymerized to form a polymer of ABBAABAB);
- alternating polymerized monomers (e.g. monomers A and B polymerized to form an ABABABAB type polymer);
- gradient (convergent) polymerized monomers (e.g. monomers A and B polymerized to form polymer of AAABAABBABBB);
block copolymers (e.g. monomers A and B polymerized to form a polymer of AAAAABBBBBB type) in which the block length of each of the blocks (2, 3, 4, 5 or even more) is important for the dispersibility of the polymeric dispersant;
- graft copolymers (graft copolymers consist of a polymeric backbone with side chains attached to the backbone); and
- mixed forms of these polymers, e.g. gradient block copolymers.
[0140] Polymeric dispersants may have different polymer structures including linear, comb / branched, star, dendritic (including dendrimers and hyperbranched polymers). For a general review of the structure of polymers, see: ODIAN, George, Principles of Polymerization, 4th Edition, WileyInterscience, 2004, pp. 1-18.
[0141] Comb / branched polymers have side branches of attached monomer molecules protruding from various central branch points along the main polymer chain (at least 3 branch points).
[0142] Star polymers are branched polymers in which three or more similar or different linear homopolymers or copolymers are bonded together to a single core.
[0143] Dendritic polymers include the classes of dendrimers and hyperbranched polymers. In dendrimers with well-defined monodisperse structures, all branch points (multi-stage synthesis) are used, while hyperbranched polymers have multiple branch points and multi-functional branches that lead to subsequent branching with polymer growth (one-stage polymerization process).
[0144] Suitable polymeric dispersants can be prepared by addition or condensation polymerization. Polymerization methods include those described in ODIAN, George, Principles of Polymerization, 4th edition, Wiley-Interscience, 2004, pp. 39-606.
[0145] Addition polymerization methods include free radical polymerization (FRP) and controlled polymerization techniques. Appropriate controlled radical polymerization methods are:
- RAFT: radical polymerization with the addition of addition-fragmentation chain transfer;
- ATRP: atom transfer radical polymerization - MADIX: radical polymerization with the addition of reactive fragmentation reversible chain transfer em using active xanthinate transfer;
- catalytic chain transfer (e.g. using cobalt complexes);
- polymerizations mediated by nitric oxide (e.g.
RATE).
[0146] Other suitable controlled polymerization methods are:
- GTP: group transfer polymerization;
- living cationic (ring-opening) polymerizations;
- anionic and coordinative polymerization with insertion and ring opening; and
- Living anionic (ring-opening) polymerization.
[0147] Radical polymerization with addition-fragmentation chain transfer (RAFT): controlled polymerization occurs through rapid chain transfer between growing polymer radicals and sleeping polymer chains. For an overview of the RAFT synthesis of dispersants with different polymeric geometries, see QUINN JF et al., Facile Synthesis of comb, star and graft polymers via reversible addition-fragmentation chain transfer (RAFT) polymerization, Journal of Polymer Science, Part A: Polymer Chemistry, vol. 40, 2956-2966, 2002. [0148] Polymerization from group transfer (GTP): the use of the GTP method for the synthesis of AB block copolymers is disclosed in SPINELLI, Harry J, GTP and its use in water based pigment dispersants and emulsion stabilizers, Proc. of 20th Int. Conf. Org. Coat. Sci. Technol., New Platz, NY, Inst. Mater. Sci. pp. 511-518.
dendritic
State univ. NY, [0149] Polymer synthesis has been described in the literature. Dendrimer synthesis in NEWCOME, GR et al. Dendritic Molecules: Concepts, Synthesis, Perspectives. VCH: WEINHEIM, 2001. The polymerization of hyperbranched polymers is described in:
BURCHARD, macromolecules No. 11, p.
IN.
Solution properties of branched Advances in Polymer Science. 1999, volume 143, 113-194. Hyperbranched materials can be obtained by multifunctional polycondensation as disclosed in FLORY, PJ Molecular size distribution in threedimensional polymers. VI. Branched polymer containing AR-Bf37
1-type units. Journal of the American Chemical Society. 1952, volume 74, pp. 2718-1723.
[0150] Living cationic polymerizations are e.g. used in the synthesis of polyvinyl ethers as disclosed in International Patent Application WO 2005/012444 (CANON), in US Pat. Ser. U.S. Patent Nos. 20050197424 (CANON) and US 20050176846 (CANON). Coordination anionic coordination polymerization is e.g. used in the synthesis of polyesters based on lactones. Living anionic polymerization with ring opening is e.g. used in the synthesis of poly (ethylene oxide) macromonomers.
[0151] Polymer free radicalisation (FRP) occurs using a chain mechanism that essentially consists of four different types of reactions including free radicals: (1) radical production from non-radical compounds (initiation), (2) addition of radical to substituted alkene (propagation ), (3) atom transfer and atom removal reactions (chain transfer and termination by disproportionation) and (4) radical-radical recombination reactions (termination by combination).
[0152] Polymeric dispersants having several of the above-mentioned polymer compositions are disclosed in US Pat. Ser. No. 6022908 (HP), US 5302197 (DU PONT) and US 6528557 (XEROX).
[0153] Suitable statistical copolymer dispersants are disclosed in US Pat. Ser. U.S. Patent No. 5,648,405 (DU PONT), U.S. Patent 6,248,532 (FUJI XEROX), U.S. Patent 6,262,207 (3M), U.S. Patent 2005,0004262 (KAO), and U.S. Patent No. 6852777 (KAO).
[0154] Suitable alternating copolymeric dispersants are described in US Pat. Ser. No. US 20030017271 (AKZO NOBEL).
[0155] Suitable block copolymer dispersants have been described in numerous patents, especially block copolymer dispersants containing hydrophobic and hydrophilic blocks. E.g. in the patent specification Ser. US 5,859,113 (DU PONT) describes block type AB copolymers, and U.S. Pat. Ser. US 6,413306 (DU PONT) discloses ABC block copolymers.
[0156] Suitable graft copolymeric dispersants are described in Canadian Patent CA 2157361 (DU PONT) (hydrophobic polymer backbone and hydrophilic side chains); other graft copolymeric dispersants are disclosed in US Pat. Ser. U.S. Patent Nos. 6,632,634 (LEXMARK) and U.S. Patent No. 6,421,715 (DU FONT).
[0157] Suitable branched copolymeric dispersants are described in US Pat. Ser. U.S. Patent Nos. US 6005023 (DU PONT), US 6031019 (KAO) and US 6127453 (KODAK).
[0158] Suitable dendritic dispersive copolymer are described, e.g., in US Pat
U.S. Patent Nos. US 6,518,670 (3M), US 6,258,896 (3M), US 2004102541 (LEXMARK), US 6,649138 (QUANTUM DOT), US 2002256230 (BASF), in European Patent Specifications
ADDITIVES) and EP 1295919 A (KODAK).
[0159] Suitable dispersing structures for inks are disclosed in: SPINELLI, Harry J., Polymeric Dispersants in InkJet technology, Advanced Materials, 1998, Vol. 10, No. 15, pp. 1215-1218.
[0160] The monomers and / or oligomers used to prepare the polymeric dispersant can be any monomers and / or oligomers that can be found in the textbook: Polymer Handbook, volume 1 + 2, 4th edition, edited by J. BRANDRUP et al., Wiley-Interscience, 1999.
[0161] Polymers useful as pigments include specific examples thereof include gelatin, casein and albumin; naturally occurring gums such as acacia and tragacanth; glycosides such as saponin; alginic acid and alginic acid derivatives such as propylene glycol alginate; and cellulose derivatives such as methyl cellulose, carboxymethyl cellulose and agents
Ser.
EP
1351759 AND
EFKA polymeric inkjet agents dispersants naturally polymers for and
proteins such as glue, carboxymethyl cellulose, ethylhydroxy cellulose; wool and silk and synthetic polymers.
[0162] Suitable examples of monomers for the synthesis of polymeric dispersants include: acrylic acid, methacrylic acid, maleic acid (or its salts), maleic anhydride, (linear, branched and cycloalkyl) (meth) acrylates, such as methyl (meth) acrylate , n-butyl (meth) acrylate, tert-butyl (meth) acrylate, cyclohexyl (meth) acrylate and 2-ethylhexyl (meth) acrylate; aryl (meth) acrylates such as benzyl (meth) acrylate and phenyl (meth) acrylate; hydroxyalkyl (meth) acrylates such as hydroxyethyl (meth) acrylate and hydroxypropyl meth) acrylate; (meth) acrylates with other types of functional groups (such as e.g. oxiranes, amino, fluoro, polyethylene oxide, phosphate) such as glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, trifluoroethyl acrylate, methoxypol (ethylene glycol) (meth) acrylate, and tripropylene glycol (meth) acrylate ; allyl derivatives such as allyl glycidyl ether; styrene compounds such as styrene, 4-methylstyrene, 4-hydroxystyrene, 4-acetostyrene and styrene sulfonic acid; (Meth) acrylonitrile; (meth) acrylamides (including N-mono and N, N-disubstituted) such as N-benzyl (meth) acrylamide; maleimides such as N-phenylmaleimide; vinyl derivatives such as vinyl alcohol, vinylcaprolactam, vinylpyrrolidone, vinylimidazole, vinylnaphthalene and vinyl halides; vinyl ethers such as vinyl methyl ether; and vinyl esters of carboxylic acids such as vinyl acetate, vinyl butyrate and vinyl benzoate. Typical condensation-type polymers include polyurethanes, polyamides, polycarbonates, polyethers, polyureas, polyimines, polyimides, polyketones, polyester, polysiloxane, phenolformaldehyde, urea-formaldehyde, melaminoformaldehyde, polysulfide, polyacetal or combinations thereof. [0163] Suitable copolymer dispersants are acrylic acid / acrylonitrile copolymer, vinyl acetate / acrylic acid copolymer, acrylic acid / acrylic acid copolymer, styrene / acrylic acid copolymer, styrene / methacrylic acid copolymer, styrene / methacrylic acid copolymer 40 / acid ester methylstyrene / acid copolymer styrene / αstyrene / αacrylic copolymer, acrylic, methylstyrene / acrylic acid / acrylic acid ester, styrene / maleic acid copolymer, styrene / maleic anhydride copolymer, vinyl naphthalene / acrylic acid copolymer, vinyl naphthalene / maleic acid copolymer, vinyl acetate / ethylene copolymer, vinyl acetate / fatty acid / ethylene copolymer, vinyl acetate / maleic acid ester copolymer, vinyl acetate / crotonic acid copolymer, copolymer vinyl acetate / acrylic acid. [0164] Suitable chemical structures of copolymeric dispersants also include:
- copolymers that are the product of a condensation reaction of poly (ethyleneimine) with a carboxyl-terminated polyester (prepared by addition polymerization); and
- copolymers that are the product of the reaction of a multifunctional isocyanate with a compound such as:
- a monosubstituted group which is capable of reacting with an isocyanate, e.g. polyester;
- a compound containing two groups capable of reacting with isocyanate (cross-linking group); or
- a compound with at least one basic ring nitrogen and a group that is capable of reacting with an isocyanate group.
[0165] A detailed list of suitable polymeric dispersants is disclosed in: MC CUTCHEON, Functional
Materials, North American Edition, Glen Rock, NJ: Manufacturing Confectioner Publishing Co., 1990, p. 110129.
[0166] Suitable pigment stabilizers are also disclosed in German Patent No. DE 19636382 (BAYER), in US Pat. Ser. No. 5720802 (XEROX), US 5713993 (DU PONT), in International Patent Application WO 96/12772 (XAAR) and in US Patent No. Ser. U.S. Patent No. 5,085,689 (BASF).
[0167] For further dispersion stability, one polymeric dispersant or a mixture of two or more polymeric dispersants can be used. Sometimes surfactants can also be used as pigment dispersants, so a combination of a polymeric dispersant with a surfactant is also possible.
[0168] The polymeric dispersant may be nonionic, anionic or cationic; salts of ionic dispersants can also be used.
[0169] The polymeric dispersant preferably has a degree of DP polymerization of from 5 to 1000, more preferably from 10 to 500 and most preferably from 10 to 100.
[0170] The polymeric dispersant preferably has a number average molecular weight Mn of 500 to 30,000, more preferably 1,500 to 10,000.
[0171] The polymeric dispersant preferably has a weight average molecular weight Mw of less than 100,000, more preferably less than 50,000 and most preferably less than 30,000.
[0172] The polymeric dispersant is preferably characterized by a PD polymer polydispersity of less than 2, more preferably less than 1.75, and most preferably less than 1.5.
[0173] Examples of commercially available polymeric dispersants include the following:
- DISPERBYK ™ dispersants available from BYK CHEMIE GMBH;
- SOLSPERSE ™ dispersants available from NOVEON;
- TEGO ™ DISPERS ™ dispersants from DEGUSSA;
- EDAPLAN ™ dispersants from MUNZING CHEMIE;
- ETHAKRYL ™ dispersants from LYONDELL;
- GANEX ™ dispersants from ISP;
- DISPEX ™ and EFKA ™ dispersants from CIBA SPECIALTY
CHEMICALS INC;
- DISPONER ™ dispersants from DEUCHEM; and JONCRYL ™ dispersants from JOHNSON POLYMER.
[0174] Particularly preferred polymeric dispersants include Solsperse ™ dispersants from NOVEON, Efka ™ dispersants from CIBA SPECIALTY CHEMICALS INC and Disperbyk ™ dispersants from BYK CHEMIE GMBH.
[0175] Particularly preferred dispersants for colored solvent-based dispersions are Solsperse ™ 32000 and 39000 dispersants from NOVEON.
[0176] Particularly preferred dispersants for colored oil-based dispersions are Solsperse ™ 11000, 11200, 13940, 16000, 17000 and 19000 from NOVEON.
[0177] Particularly preferred dispersants for UV-curable colored dispersions are Solsperse ™ 32000 and 39000 dispersants from NOVEON.
[0178] The polymeric dispersant is preferably used in an amount of 2 to 600% by weight, more preferably 5 to 200% by weight based on the weight of the pigment.
Dispersion synergists [0179] A dispersion synergist typically consists of an anionic portion and a cationic portion. The anionic part of the dispersion synergist has some molecular similarity to the color pigment, while the cationic part of the dispersion synergist contains one or more protons and / or cations to equalize the charge of the anionic part of the dispersion synergist.
[0180] The synergist is preferably added in less than the polymeric dispersant (s). The ratio of polymeric dispersant to dispersion synergist depends on the pigment and should be determined experimentally. Typically, the weight% polymeric dispersant / weight% dispersion synergist ratio is from 2: 1 to 100: 1, preferably from 2: 1 to 20: 1.
[0181] Suitable dispersion synergists that are commercially available include Solsperse ™ 5000 and Solsperse ™ 22000 from
NOVEON.
[0182] A particularly preferred pigment for the fuchsin ink used in the inkjet ink set for making decorative laminates is the diketopyrrolo-pyrrole pigment. To obtain excellent dispersion stability and quality, the pigment dispersion synergist diketopyrrolo-pyrrole was preferably used, as disclosed in pending European Patent Application EP 05111360.
[0183] When dispersing CI Pigment 15: 3, the use of sulfonated Cu-phthalocyanine as a dispersion synergist, e.g. Solsperse ™ 5000 from NOVEON, is preferred. Suitable dispersion synergists for yellow inkjet inks include those disclosed in pending European Patent Application EP 05111357.
Dispersion media [0184] In one embodiment, the dispersion medium consists of an organic solvent (organic solvents). Suitable organic solvents include alcohols, ketones, esters, ethers, glycols and polyglycols and derivatives thereof, lactones, N-containing solvents such as amides. Mixtures of one or more such solvents are preferably used.
[0185] Examples of suitable alcohols include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, heptyl alcohol, octyl alcohol, cyclohexyl alcohol, benzyl alcohol, phenylethyl alcohol, phenylpropyl alcohol, furfuryl alcohol, anise alcohol and fluoroalcohols.
[0186] Examples of suitable ketones include acetone, methyl ethyl ketone, methyl-n-propyl ketone, methyl isopropyl ketone, methyl n-butyl ketone, methyl isobutyl ketone, methyl namyl ketone, methyl isoamyl ketone, diethyl ketone, ethyl n-propyl ketone, ethyl isopropyl ketone, ethyl isopropyl ketone, -n-propylketone, diisobutylketone, cyclohexanone, methylcyclohexanone and isophorone, 2,4pentanedione and hexafluoroacetone.
[0187] Examples of suitable esters include methyl acetate, ethyl acetate, n-propyl acetate, isopropyl acetate, nbutyl acetate, isobutyl acetate, hexyl acetate, octyl acetate, benzyl acetate, phenoxyethyl acetate, ethyl phenyl acetate, methyl lactate, ethyl lactate, propyl lactate butyl lactate; methyl propionate, ethyl propionate, benzyl propionate, ethylene carbonate, propylene carbonate, amyl acetate, ethyl benzoate, butyl benzoate, butyl laurate, isopropyl myristate, isopropyl palmitate, triethyl phosphate, tributyl phosphate, diethyl phthalate, dibutyl malonate, dipropyl malonate , diethyl succinate, dibutyl succinate, diethyl glutarate, diethyl adipate, dibutyl adipate and diethyl sebacate.
[0188] Examples of suitable ethers include butyl phenyl ether, benzyl ethyl ether, hexyl ether, diethyl ether, dipropyl ether, tetrahydrofuran and dioxane.
[0189] Examples of suitable glycols and polyglycols include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol and tripropylene glycol.
[0190] Examples of suitable glycol and polyglycol derivatives include ethers such as alkylene glycol monoalkyl ethers, alkylene glycol dialkyl ethers, poly (alkylene glycol) monoalkyl ethers, poly (alkylene glycol) dialkyl ethers and esters of the above glycol ethers such as acetate and propionate . in the case of dialkyl ethers, only one ether group can be esterified (resulting in a mixed ether / ester compound) or both ether groups (resulting in a dialkyl ester in effect).
[0191] Examples of suitable alkylene glycol monoalkyl ethers include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, mono-2-ethylhexyl ether, ethylene glycol monoethyl ether propylene glycol monomethyl glycol, propylene glycol monoethyl ether, propylene glycol mono-ethyl ether, propylene glycol mono-n-butyl ether, propylene glycol mono-iso-butyl ether, propylene glycol mono-t-butyl ether and propylene glycol monophenyl ether.
[0192] Examples of suitable alkylene glycol dialkyl ethers include ethylene glycol dimethyl ether, ethylene glycol diethyl ether, ethylene glycol methyl ethyl ether, ethylene glycol dibutyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether and dibutyl ether.
[0193] Examples of suitable poly (alkylene glycol) monoalkyl ethers include diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-propyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol monohexyl ether, , triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol n-propyl ether, dipropylene glycol mono-n-butyl ether, dipropylene glycol mono-t-butyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, mono-n-propylene glycol ether tripropylene glycol mono-n-butyl.
[0194] Examples of suitable poly (alkylene glycol) dialkyl ethers include diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, tetraethylene glycol dimethyl ether, diethylene glycol diethyl ether, triethylene glycol diethyl ether, diethylene glycol diethyl ether, triethylene glycol, tetraethylene glycol methyl ether, diethylene glycol di-n-propyl ether, diethylene glycol diisopropyl ether, dipropylene glycol dimethyl ether, dipropylene glycol diethyl ether, dipropylene glycol di-n-propyl ether, dipropylene glycol di-t-butyl ether, tripropylene glycol dimethyl ether and tripropylene glycol diethyl ether. [0195] Examples of suitable glycol esters include ethylene glycol monomethyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monopropyl ether acetate, ethylene glycol monobutyl ether acetate, diethylene glycol monoethyl ether acetate, monobutyl ether glycol diethylene glycol acetate propylene glycol monoethyl ether acetate, dipropylene glycol monomethyl ether acetate and propylene glycol monomethyl ether propionate.
[0196] Preferred solvents for use in pigment dispersions and inkjet inks include one or more poly (alkylene glycol) dialkyl ethers represented by the formula (PAG)
<img file="PL1935652T3_D0001.tif" />
Formula (PAG) in which,
R<sub>1</sub> and R<sub>2</sub> are each independently an alkyl group having from 1 to 4 carbon atoms;
Y is an ethylene group and / or a propylene group; n is an integer from 4 to 20. Preferably, the solvent is a mixture of two or more poly (alkylene glycol) dialkyl ethers represented by formula (PAG).
[0197] Alkyl groups R<sub>1</sub> and R<sub>2</sub> poly (alkylene glycol) dialkyl ethers of formula (PAG) are preferably methyl and / or ethyl. Most preferably both R alkyl groups<sub>1</sub> and R<sub>2</sub> are methyl groups.
[0198] In a preferred embodiment, the poly (alkylene glycol) dialkyl ethers of formula (PAG) are poly (ethylene glycol) dialkyl ethers.
[0199] In another preferred embodiment, the mixture of 2, 3, 4 or more poly (alkylene glycol) dialkyl ethers, more preferably poly (ethylene glycol) dialkyl ethers is present in the pigment dispersion or in the inkjet ink.
[0200] Suitable mixtures of poly (alkylene glycol) dialkyl ethers for pigment dispersions include mixtures of poly (ethylene glycol) dimethyl ethers with a molecular weight of at least 200, such as Polyglycol DME 200 ™, Polyglycol DME 250 ™ and Polyglycol DME 500 ™ from CLARIANT . The poly (alkylene glycol) dialkyl ethers used in the non-aqueous inkjet inks preferably have an average molecular weight from 200 to 800 and more preferably do not contain poly (alkylene glycol) dialkyl ethers with a molecular weight greater than 800. The mixture of poly (alkylene glycol) dialkyl ethers is preferably at room temperature, a homogeneous liquid mixture.
[0201] Suitable commercial solvents based on glycol ethers include Cellosolve ™ and Carbitol ™ solvents from UNION CARBIDE, Ektasolve ™ solvents from EASTMAN, Dowanol ™ solvents from DOW, Oxitoll solvents, Dioxitoll solvents, Proxitoll ™ solvents, and Diproxitoll ™ solvents, and SHELL CHEMICAL solvents Arcosolv ™ from LYONDELL. [0202] Lactones are compounds having in their structure a ring formed by ester bonds and may include γ-lactone (5-membered ring structure), δ-lactone (6-membered ring structure) or ε-lactone (7-membered ring structure) . Suitable examples of lactones include γ-butyrolactone, γ-valerolactone, γ-hexalactone, γheptalactone, γ-octalactone, γ-nonalactone, γ-decalactone, γundecalactone, δ-valerolactone, δ-hexalactone, δ-heptalact nonalactone, δ-decalactone, δ-undecalactone and εcaprolactone.
[0203] Suitable examples of N-containing organic solvents include 2-pyrrolidone, N-methylpyrrolidone, N-ethyl-2-pyrrolidone, N-octyl-2-pyrrolidone, N-dodecyl-2-pyrrolidone, N, N-dimethylacetamide, N , N-dimethylformamide, acetonitrile and N, N-dimethyldodecanamide.
[0204] In another embodiment, the dispersion medium contains oil type liquids, alone or in combination with an organic solvent (organic solvents). Suitable organic solvents include alcohols, ketones, esters, ethers, glycols and polyglycols and derivatives thereof, lactones, N-containing solvents such as amides, higher fatty acid esters and mixtures of one or more solvents as described above for solvent-based dispersion media .
[0205] The amount of polar solvent is preferably less than the amount of oil. The organic solvent preferably has a high boiling point, preferably above 200 ° C. Examples of suitable combinations are disclosed in GB 2303376 (FUJITSU ISOTEC), especially for the use of oleyl alcohol and in EP 1157070 A (MARCONI DATA SYSTEMS) for a combination of oil and volatile organic solvent.
[0206] Suitable oils include saturated hydrocarbons and unsaturated hydrocarbons, aromatic oils, paraffin oils, extracted paraffin oils, naphthenic oils, extracted naphthenic oils, hydrotreated light or heavy oils, vegetable oils, vaseline oils, petroleum oils, halogenated hydrocarbons, halogenated their derivatives and mixtures.
[0207] Hydrocarbons may be selected from straight or branched chain aliphatic hydrocarbons, alicyclic hydrocarbons and aromatic hydrocarbons. Examples of hydrocarbons include saturated hydrocarbons such as nhexane, isohexane, n-nonane, isononane, dodecane and isododecane; unsaturated hydrocarbons such as 1-hexene, 1-heptene and 1-octene; cyclic saturated hydrocarbons such as cyclohexane, cycloheptane, cyclooctane, cyclodecane and decalin; cyclic unsaturated hydrocarbons such as cyclohexene, cycloheptene, cyclooctene, 1,3,5,7-cyclooctatetraene; and cyclododecene; and aromatic hydrocarbons such as benzene, toluene, xylene, naphthalene, phenanthrene, anthracene and their derivatives. The term paraffin oil is often used in the literature. Suitable paraffin oils may include normal paraffin type oils (octane and larger alkanes), isoparaffins (isooctane and larger isoalkanes) and cycloparaffins (cyclooctane and larger cycloalkanes) and mixtures of paraffin oil. The term "liquid paraffin" is often used to refer to a mixture containing mainly three components, such as normal paraffin, isoparaffin and monocyclic paraffin, which is obtained by the strong refining of a fraction of a relatively volatile lubricating oil using sulfuric acid washing or a similar method as described in the patent description Ser. Of US No. 6730153 (SAKATA INX). Suitable hydrocarbons have also been described as de-aromatized petroleum distillates.
[0208] Suitable examples of halogenated hydrocarbons include methylene dichloride, chloroform, tetrachloromethane and methyl chloroform. Other suitable examples of halogenated hydrocarbons include perfluoroalkanes, fluorine-based inert liquids and fluoride hydrocarbon iodides.
[0209] Suitable examples of silicone oils include poly (dialkylsiloxane) (e.g., hexamethyldisiloxane, tetramethyldisiloxane, octamethyltrisiloxane, hexamethyltrisiloxane, heptamethyltrisiloxane, decamethyltetrasiloxane, trifluoropropylhexyltrisiloxyltriethyltrisiloxyltrilyl hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, tetramethylcyclotetrasiloxane, tetra (trifluoropropyl) tetramethylcyclotetrasiloxane) and methylphenyl silicone oil.
[0210] White oil is a term used for mineral vaseline oils that are highly refined mineral oils consisting of saturated aliphatic and alicyclic non-polar hydrocarbons. White oils are hydrophobic, colorless, tasteless, odorless and do not change color over time.
[0211] Vegetable oils include semi-drying oils such as soybean oil, cottonseed oil, sunflower oil, grape seed oil, mustard oil, sesame oil and corn oil; non-drying oils such as olive oil, peanut oil and tsubaki oil; and drying oils such as linseed oil and safflower oil, these vegetable oils may be used alone or as a mixture thereof.
[0212] Examples of other suitable oils include petroleum oils, non-drying oils and semi-drying oils.
[0213] Suitable oils available on the market include aliphatic hydrocarbons such as the Isopar ™ series (isoparaffins) and the Varsol / Naphtha series from EXXON CHEMICAL, the Soltrol ™ series and hydrocarbons from CHEVRON PHILLIPS CHEMICAL and the Shellsol ™ series from SHELL CHEMICALS.
[0214] Suitable commercial normal paraffins include the Norpar ™ range from EXXON MOBIL CHEMICAL.
[0215] Suitable commercial naphthenic hydrocarbons include the Nappar ™ range from EXXON MOBIL CHEMICAL.
[0216] Suitable commercially available de-aromatized petroleum distillates include Exxsol ™ type D from EXXON MOBIL CHEMICAL.
[0217] Suitable commercial fluorinated hydrocarbons include fluorocarbons from DAIKIN INDUSTRIES LTD, Chemical Division.
[0218] Suitable commercially available silicone oils include a series of liquid silicones from SHIN-ETSU CHEMICAL, Silicone Division.
[0219] Suitable commercially available vaseline oils include Witco ™ vaseline oils from CROMPTON CORPORATION.
[0220] If the non-aqueous pigment dispersion is a curable pigment dispersion, the dispersion medium contains one or more monomers and / or oligomers to form a liquid dispersion medium. Sometimes, it may be advantageous to add a small amount of organic solvent to improve the dissolution of the dispersant. The organic solvent content should be less than 20% by weight based on the total weight of the inkjet ink. In other cases, it may be advantageous to add a small amount of water, e.g., to improve the spread of the inkjet ink on a hydrophilic surface, but preferably the inkjet ink contains no water.
[0221] Preferred organic solvents include alcohols, aromatic hydrocarbons, ketones, esters, aliphatic hydrocarbons, higher fatty acids, carbitols, ethylene glycol derivatives (cellosolves), higher fatty acid esters. Suitable alcohols include methanol, ethanol, propanol and 1-butanol, 1-pentanol, 2-butanol, t-butanol. Suitable aromatic hydrocarbons include toluene and xylene. Suitable ketones include methyl ethyl ketone, methyl isobutyl ketone, 2,4-pentanedione and hexafluoroacetone. Glycol, glycol ethers, N-methylpyrrolidone, N, N-dimethylacetamide, NN-dimethylformamide can also be used.
[0222] In the case of a curable inkjet ink, the dispersion medium preferably contains monomers and / or oligomers.
Monomers and oligomers [0223] Any monomer or oligomer can be used as the curable compound for the curable inkjet ink. A combination of monomers, oligomers and / or prepolymers may also be used. Monomers, oligomers and / or prepolymers may have different degrees of functionality and a mixture including combinations of mono-, di-, trii / or higher functionality monomers, oligomers and / or prepolymers may be used. The viscosity of the inkjet ink can be controlled by changing the ratio between monomers and oligomers.
[0224] Any method of conventional methods can be used, such as radical polymerization, light curing system using a photo-acid or photo-base generator, or light-induced alternating copolymerization. In general, radical polymerization and cationic polymerization are preferred and light induced alternation copolymerization that does not require the use of an initiator can also be used. In addition, a hybrid system combining the above systems is also effective.
[0225] Cationic polymerization is more effective due to the lack of oxygen polymerization inhibition, however it is expensive and slow, especially in conditions of high relative humidity. If cationic polymerization is used, it is preferred to use an epoxy compound together with an oxetane compound to increase the polymerization rate. Radical polymerization is the preferred polymerization process.
[0226] Any polymerizable compound commonly known in the art may be used. Particularly preferred for use as radiation curable compounds in radiation curable inkjet ink include compounds such as monofunctional and / or multifunctional acrylate monomers, oligomers or prepolymers such as isoamyl acrylate, stearyl acrylate, lauryl acrylate, octyl acrylate, isoamyl acrylate, isostearyl acrylate, 2-ethylhexyl diglycol acrylate, 2-hydroxybutyl acrylate, 2-acryloyloxyethylhexahydrophthalic acid, butoxyethyl acrylate, ethoxydiethylene glycol acrylate, methoxydiethylene glycol acrylate, methoxypol (ethylene glycol) acrylate, propoxy methoxyglycol acrylate, phenoxyethyl acrylate, tetrahydrofurfuryl acrylate, isobornyl acrylate, 2-hydroxy-2-hydroxyethyl acrylate acrylate , vinyl ether acrylate, ethoxy acrylate vinyl ether (meth) acrylate, 2-acryloyloxyethyl succinic acid, acid
2-acryloyloxyethylphthalic acid, 2-acryloxyethyl-2-hydroxyethylphthalic acid, elastically modified acrylate and t-butylcyclohexyl acrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, poly (ethylene glycol diacrylate), diacrylate diacrylate, propylene), 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, neopentyl glycol diacrylate, diacrylate, dimethyloltricyclodecane diacrylate, bisphenol A EO (ethylene oxide) adduct diacrylate, bisphenol A PO (propylene oxide) adduct diacrylate, hydroxypivalate neopentyl glycol diacrylate, propoxylated neopentyl glycol diacrylate, alkoxylated dimethyloltricyclodecane diacrylate and polytetramethylene glycol diacrylate, trimethylolpropane triacrylate, trimethylolpropane triacrylate, EO modified trimethylolpropane triacrylate, tri (propylene glycol), caprolactone-modified trimethylolpropane triacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, ethoxypentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, dithrimethylolpropane tetraacrylate, propoxyglycerol or tetracrylactyltacrylacrylate tetracrylate, or acrylamide or substituted acrylamide such as acryloylmorpholine.
[0227] Other suitable monofunctional acrylates include caprolactone acrylate, cyclic trimethylolpropane dimethoxymethane acrylate, ethoxylated nonylphenol acrylate, isodecyl acrylate, isooctyl acrylate, octyldecyl acrylate, alkoxylated phenol acrylate, tridecyl acrylate acrylate alkoxylate
[0228] Other suitable difunctional acrylates include alkoxylated cyclohexanedimethanol diacrylate, alkoxylated hexanediol diacrylate, dioxane glycol diacrylate, dioxane glycol diacrylate, cyclohexane 54 dimethanol diacrylate, diethylene glycol diacrylate and n-glycol diacrylate.
[0229] Other suitable trifunctional acrylates include propoxylated glycerine triacrylate and propoxylated trimethylolpropane triacrylate.
[0230] Other higher-functional acrylates include ditrimethylolpropane tetraacrylate, dipentaerythritol pentaacrylate, ethoxylated pentaerythritol tetraacrylate, methoxylated glycol acrylates, and acrylate esters.
[0231] In addition, methacrylates corresponding to the above-mentioned acrylates may be used with these acrylates. Of the methacrylates, methoxypol (ethylene glycol) methacrylate, methoxyglycol methoxy acrylate, hydroxyethyl methacrylate, phenoxyethyl methacrylate, cyclohexyl methacrylate, tetraethylene glycol dimethacrylate and poly (ethylene glycol) dimethacrylate are more suitable for their high sensitivity and due to their high sensitivity .
[0232] In addition, the inkjet inks may also contain polymerizable oligomers. Examples of such polymerizable oligomers include epoxy acrylates, aliphatic urethane acrylates, aromatic urethane acrylates, polyester acrylates and straight chain acrylic oligomers.
[0233] Suitable examples of styrene compounds include styrene, p-methylstyrene, p-methoxystyrene, β-methylstyrene, pmethyl-e-methylstyrene, α-methylstyrene and p-methoxy-e-methylstyrene.
[0234] Suitable examples of vinylnaphthalene compounds include 1-vinylnaphthalene, α-methyl-1-vinylnaphthalene, β-methyl-1-vinylnaphthalene, 4-methyl-1-vinylnaphthalene and 4-methoxy-1-vinylnaphthalene.
[0235] Suitable examples of N-vinyl compounds include N-vinylcarbazole, N-vinylpyrrolidone, N-vinylindole, N-vinylpyrrole, N-vinylphenothiazine, N-vinylacetoanilide, N-vinylethylacetoamide, N-vinyl succinimide, N-vinylnaphthalimide -winyloimidazol.
[0236] The cationically polymerizable compound of the inkjet ink may be one or more monomers, one or more oligomers or a combination thereof. [0237] Suitable examples of cationically curable compounds can be found in Advances in Polymer Science, 62, pp. 1 to 47 (1984), JV Crivello.
[0238] The cationically curable compound may include at least one group, such as an olefin, thioether, acetal, thioxane, thiethane, aziridine, N-, O-, S- or P-heterocyclyl, aldehyde, lactam or cyclic ester group.
[0239] Examples of cationically polymerizable compounds include monomers and / or oligomers of epoxides, vinyl ethers, styrenes, oxetanes, oxazolines, vinylnaphthalenes, N-vinyl heterocyclic compounds, tetrahydrofurfuryl compounds. [0240] The cationically polymerizable monomer may be mono-, di- or multifunctional or a mixture thereof. [0241] Suitable cationically curable compounds containing at least one epoxy group are listed in the Handbook of Epoxy Resins, Lee and Neville, McGraw Hill Book Company, New York (1967) and in Epoxy Resin Technology, PF Bruins, John Wiley and Sons, New York (1968).
[0242] Examples of cationically curable compounds containing at least one epoxy group include 1,4-butanedioliglycidyl ether, 3- (bis (glycidyloxymethyl) methoxy) 1,2-propanediol, limonene oxide, 2-biphenylglycidyl ether, 3,4-epoxycyclohexyl carboxylate ', 4'-epoxycyclohexane, epoxies based on the epichlorohydrinbisphenol S complex, epoxidized styrene compounds and more epoxies based on the epichlorohydrin-bisphenol F and A complex, and epoxidized novolacs.
[0243] Suitable epoxy compounds comprising at least two epoxy groups in the molecule are alicyclic polyepoxide, polyglycidyl ester of polybasic acid, polyglycidyl ether of polyol, polyglycidyl ether of polyoxyalkylene glycol, polyglycidyl ester of aromatic polyol, polyglycidyl ether of aromatic polyol, urethane polyepoxy compound, and polyepoxy polybutadiene. [0244] Examples of cycloaliphatic bisepoxides include copolymers of epoxides and hydroxyl compounds such as glycols, polyols or vinyl ether such as carboxylate
3,4-epoxycyclohexylmethyl-3 ', 4'-epoxycyclohexylcarboxylate; bis (3,4-epoxycyclohexylmethyl) adipate; limonene bisepoxide; diglycidyl ester of hexahydrophthalic acid.
[0245] Examples of vinyl ethers containing at least one vinyl ether group include ethyl vinyl ether, n-butyl vinyl ether, isobutyl vinyl ether, octadecyl vinyl ether, cyclohexyl vinyl ether, butanedi-divinyl ether, hydroxybutyl vinyl ethylene ether, phenylethyl vinyl ether, ethylene vinyl ether, -methoxyphenyl vinyl, α-methylphenyl vinyl ether, β-methylisobutyl vinyl ether and β-chloroisobutyl vinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, dodecyl vinyl ether, diethylene glycol monovinyl ether, cyclohexanedimethanol divinyl ether, 4- (vinyloxy) butyl butoxyl benzoate, butyl 4- butyl] butyl bis [4- (vinyloxy) butyl], 4- (vinyloxymethyl) cyclohexylmethyl benzoate, bis [4- (vinyloxy) butyl] isophthalate, bis [4- (vinyloxymethyl) cyclohexylmethyl] glutarate, tris [4- (vinyloxy) butyl] trimellitate, 4- (vinyloxy) butyl stearate, bis [4- (vinyloxy) butyl] hexanediyl biscarbamate, bis [4- (vinyloxy) methyl] cyclohexyl] methyl terephthalate, bis [4] isophthalate - (vinyloxy) methyl] cyclohexyl] methyl], bis [4- (vinyloxy) butyl] (4-methyl-1,3-phenylene) biscarbamate, bis [4-vinyloxy) butyl] (methylenedio-4,1-phenylene) biscarbamate and 3 amino-1-propanol vinyl ether.
[0246] Suitable examples of oxetane compounds containing at least one oxetane group include 357 ethyl-3-hydroxy-methyl-1-oxetane, an oligomeric mixture
1,4-bis [3-ethyl-3-oxetanylmethoxy) methyl] benzene, 3-ethyl3-phenoxymethyloxetane, bis ([1-ethyl (3-oxetanyl)] methyl) ether, 3-ethyl-3 - [(2- ethylhexyloxy) methyl] oxetane, 3-ethyl [(triethoxysilylpropoxy) methyl] oxetane and 3,3-dimethyl-2- (p-methoxyphenyl) oxetane.
[0247] A preferred class of monomers and oligomers that can be used in both radiation curable and cationically curable compositions includes vinyl ether acrylates such as those described in US Pat. Ser. US 6,310115 (AGFA), incorporated herein by reference. Particularly preferred compounds are 2- (2-vinyloxyethoxy) ethyl (meth) acrylate, the most preferred compound is 2- (2-vinyloxyethoxy) ethyl acrylate.
Initiators [0248] The curable inkjet ink preferably also contains an initiator. The initiator typically initiates the polymerization reaction. The initiator may be a thermal initiator, but is preferably a photoinitiator. The photoinitiator needs less energy to activate than monomers, oligomers and / or prepolymers to produce the polymer. A photoinitiator suitable for use in curable inkjet inks may be a Norrish type I initiator, a Norrish type II initiator or a photo-acid generator.
[0249] A thermal initiator (s) suitable for use in the curable inkjet ink may be a compound such as tert-amyl peroxybenzoate, 4,4-azobis (4-cyanovaleric acid), 1,1'azobis (cyclohexankarbonitrile), 2,2'-azobisisobutyronitrile (AIBN), benzoyl peroxide, 2,2-bis (tert-butylperoxy) butane, 1,1-bis (tert-butylperoxy) cyclohexane, 1,1-bis (tert-butylperoxy) cyclohexane, 2 5-bis (tert-butylperoxy) -2,5-dimethylhexane. 2,5-bis (tert-butylperoxy) -2,5-dimethyl-3-hexyn, bis (1- (tert-butylperoxy) -1-methylethyl) benzene, 1,1-bis (tert-butylperoxy) -3, 3,5-trimethylcyclohexane, tert-butyl hydrogen peroxide, tert-butyl peracetate, tert-butyl peroxide, tert-butyl peroxybenzoate, tert-butylperoxyisopropyl carbonate, cumene hydroperoxide, cyclohexanone peroxide, dicumylperoxide, peroxyloxide, peroxide, peroxide potassium peroxosulphate. [0250] A photoinitiator or photoinitiator system absorbs light and is responsible for the production of initiating substances such as free radicals and cations. Free radicals and cations are high-energy particles that induce polymerization of monomers, oligomers and polymers and, in the case of multifunctional monomers and oligomers, also induce cross-linking.
[0251] Irradiation with actinic radiation can be accomplished in two stages by changing the wavelength or intensity. In such cases, it is preferred to use 2 types of photoinitiator together. [0252] A combination of different types of initiator may also be used, e.g. a photoinitiator and a thermal initiator. [0253] The preferred Norrish type I initiator is selected from the group consisting of benzoin ethers, benzyl ketals, α, α-dialkoxyacetophenones, α-hydroxyalkylphenones, α-aminoalkylphenones, acylphosphine oxides, acylphosphine sulphides, αhalo ketone, α-haloacrylates, α-halogeno
[0254] A preferred Norrish type II initiator is selected from the group consisting of benzophenones, thioxanthones, 1,2-diketones and anthraquinones. The preferred co-initiator is selected from the group consisting of an aliphatic amine, aromatic amine and thiol. Tertiary amines, heterocyclic thiols and 4-dialkylaminobenzoic acid are particularly preferred co-initiators.
[0255] Suitable photoinitiators are disclosed in CRIVELLO, JV et al. Tom III: Photoinitiators for Free Radical Cationic. 2nd edition. Editors of BRADLEY, G., London, UK: John Wiley and Sons Ltd, 1998. pp. 287-294.
mixture combination [0256] Specific examples of photoinitiators may include, but are not limited to, the following compounds or combinations thereof: benzophenone and substituted benzophenones, 1-hydroxycyclohexylphenyl ketone, thioxanthones such as isopropylthioxantone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-benzyl-2-dimethylamino- (4-morpholinophenyl) butan-1-one, dimethylketal , bis (2,6-dimethylbenzoyl) -2,4,4-trimethylpentylphosphine oxide, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, 2-methyl 1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, 2 , 2-dimethoxy-1,2-diphenylethan-1-one or 5,7-diodo-3-butoxy-6-fluorone, diphenyl iodonium fluoride and triphenyl sulfonium hexafluophosphate.
[0257] Suitable commercially available photoinitiators include Irgacure ™ 184, Irgacure ™ 500, Irgacure ™ 907, Irgacure ™ 369, Irgacure ™ 1700, Irgacure ™ 651, Irgacure ™ 819, Irgacure ™ 1000, Irgacure ™ 1300, Irgacure ™ 1870, Darocur ™ 1173, Darocur ™ 2959, Darocur ™ 4265 and Darocur ™ ITX available from CIBA SPECIALTY CHEMICALS, Lucerin TPO available from BASF AG, Esacure ™ KT046, Esacure ™ KIP150, Esacure ™ KT37 and Esacure ™ EDB available from LAMBERTI, H-Nu ™ 470 and H-Nu ™ 470X available from SPECTRA GROUP Ltd.
[0258] Suitable cationic photoinitiators include compounds that form aprotic or Bronstead acids when exposed to ultraviolet and / or visible light sufficient to initiate polymerization. The photoinitiator used may be a single compound, two or more two or more co-initiators. Non-limiting examples of suitable cationic photoinitiators include aryldiazonium salts, diaryliodonium salts, triarylsulfonium salts, triarylselenonium salts, etc.
[0259] The curable inkjet ink may contain a photoinitiator system comprising one or more photoinitiators and one or more sensitizers that transfer energy to the photoinitiator (photoinitiators).
active compounds or various compounds, i.e.
Suitable sensitizers include photoreduced dyes such as xanthene, fluorene, benzoxanthene, benzothioxanthene, thiazine, oxazine, coumarin, pyronine, porphyrin, acridine, azo compound, diazo compound, cyanine, merocyanine, diarylmethylmethyl compound, an anthylmethylene compound, an anthylmethylene compound, , fluorochrome, quinoline, tetrazole, naphthol, benzidine, rhodamine, indigo and / or indantrene. The amount of sensitizer is generally from 0.01 to 15% by weight, preferably from 0.05 to 5% by weight, in each case based on the total weight of the curable inkjet ink.
[0260] To further increase the photosensitivity, the curable inkjet ink may further contain co-initiators. For example, combinations of titanocenes and trichloromethyl-s-triazines, titanocenes and ketoxime ethers and acridines and trichloromethyl-s-triazines are known. Further increase in sensitivity can be achieved by adding dibenzacetone or amino acid derivatives. The amount of co-initiator or co-initiators is generally from 0.01 to 20% by weight, preferably from 0.05 to 10% by weight, in each case based on the total weight of the curable inkjet ink.
[0261] Suitable examples of co-initiators can be divided into 4 groups:
(1) tertiary aliphatic amines such as methyldiethanolamine, dimethylethanolamine, triethanolamine, triethylamine and N-methylmorpholine;
(2) aromatic amines such as amyl paradimethylaminobenzoate, 2-n-butoxyethyl 4- (dimethylamino) benzoate, 2- (dimethylamino) ethyl benzoate, ethyl 4- (dimethylamino) benzoate and 2-ethylhexyl benzoate;
(3) (meth) acrylated amines, such as dialkylaminoalkyl (meth) acrylates (e.g., diethylaminoethyl acrylate) or N-morpholinoalkyl (meth) acrylates (e.g., N-morpholinoethyl acrylate); and (4) amides or ureas.
Preferred co-initiators are aminobenzoates.
[0262] A preferred system of initiators includes 2,2'-bis (ochlorophenyl) -4,4 ', 5,5'-tetrafenyl- (7Cl, 8Cl) -4,4'-bi-4Himidazole with a structure corresponding to the following chemical formula :
<img file="PL1935652T3_D0002.tif" />
in the presence of a co-initiator such as 2-mercaptobenzoxazole.
[0263] Another preferred type of initiator is an oxime ester. A suitable example has the following chemical formula:
<img file="PL1935652T3_D0003.tif" />
by weight of the total weight of the curable liquid and more preferably from 1 to 15% by weight of the total weight of the curable inkjet ink.
[0265] Irradiation with actinic radiation can be carried out in two stages, by changing the wavelength or intensity. In these cases, it is preferable to use 2 types of photoinitiator together.
Inhibitors [0266] Suitable polymerization inhibitors include substances such as phenothiazine, phenolic type antioxidants, spatially expanded amine light stabilizers, phosphorus type antioxidants, hydroquinone monomethyl ether commonly used in (meth) acrylate monomers, and hydroquinone can also be used. t-butyl catechol, pyrogallol. Of the compounds mentioned above, a phenolic compound having a double bond in molecules derived from acrylic acid is particularly advantageous in that it exhibits a polymerization inhibiting effect even when heated in a closed, oxygen-free environment. Suitable inhibitors include, e.g. Sumilizer ™ GA-80, Sumilizer ™ GM and Sumilizer ™ GS manufactured by Sumitomo Chemical Co., Ltd, Ciba Irgastab ™ UV10 from CIBA Specialty Products and Genorad ™ 16 available from RAHN.
[0267] Since the addition of an excessive amount of these polymerization inhibitors will reduce the susceptibility to curing, it is preferable to determine the amount that is polymerizable before mixing. The amount of polymerization is generally from 200 to 20,000 ppm of the total weight of the curable inkjet ink.
inhibitor prevention
Surfactants [0268] Surfactants (surfactants) can be anionic, cationic, nonionic, or amphoteric and are usually added in an overall amount of less than 20% by weight based on the total weight of the pigmented inkjet ink and especially in an overall amount of less than 10% by weight based on the total weight of the pigmented inkjet ink.
[0269] Suitable surfactants include fluorinated surfactants, fatty acid salts, salts of higher alcohol esters, alkyl benzene sulfonate salts, salts of sulfosuccinate esters and salts of phosphate esters of higher alcohol (e.g. sodium dodecylbenzene sulfonate and sodium dioctyl sulfosuccinate), ethylene oxide adducts with higher alcohol, ethylene oxide and alkylphenol adducts, ethylene oxide adducts with polyhydric alcohol fatty acid ester, and acetylene glycol and its adducts with ethylene oxide, e.g. non-phenylethoxyether<sup>TM</sup> 104,
104H, 440, 465 and TG available from AIR PRODUCTS & CHEMICALS
INC.).
[0270] For non-aqueous inkjet inks selected from preferred surfactants include fluorinated surfactants such as fluorinated hydrocarbons surfactant, crosslinking activity acrylates, siloxanes, fluorinated silicone surfactants. Silicones typically include siloxanes and may be alkoxylated, polyether modified, polyether modified hydroxy functional groups, amine modified, epoxy modified, as well as other modifications or combinations thereof. Preferred siloxanes are polymeric, e.g. polydimethylsiloxanes.
[0271] In the curable inkjet ink a fluorinated or silicone compound may be used as preferably a surfactant capable of being polymerized surface monomers include silicone modified methacrylates, polyether acrylated fluorinated methacrylates. polymerization monomers having surface activity may be mono-, di-, tri- or larger (meth) acrylates or mixtures thereof.
showing silicone acrylated siloxanes, Admissible modified acrylates and
Binders [0272] The colored inkjet inks in an inkjet ink set according to the invention may contain a binding resin. The binder acts as a viscosity regulating agent as well as an agent that affixes to a substrate material, e.g. a polyvinyl chloride substrate material. The binder preferably has good solubility in the solvent (s). [0273] The non-aqueous inkjet ink compositions preferably contain a binder resin. The binder acts as a viscosity regulating agent as well as an agent that affords the ability to attach to a polymer resin substrate material, e.g. to a polyvinyl chloride substrate material, also called a vinyl substrate material. The binder should be selected so that it shows good solubility in the solvent (s).
[0274] Suitable examples of binding resins include acrylic resins, modified acrylic resins, styrene acrylic resins, acrylic copolymers, acrylate resins, aldehyde resins, rosins, rosin resins, modified rosins and modified rosin resins, acetyl polymers, acetal resins such as polyvinyl butyrals ketone resins, phenol resins and modified phenol resins, maleic resins and modified maleic resins, terpene resins, polyester resins, polyamide resins, polyurethane resins, epoxy resins, vinyl resins, vinyl chloride-vinyl acetate copolymer resins, cellulose resins such as nitrocellulose, cellulose acetopropionate and cellulose acetate and butyrate and vinyl toluene-α-methylstyrene copolymer resin. These binders can be used alone or as a mixture thereof. The binder is preferably a film-forming thermoplastic resin.
[0275] The amount of binder resin in the inkjet ink is preferably from 0.1 to 30% by weight, more preferably from 1 to 20% by weight, most preferably from 2 to 10% by weight based on the total weight of the inkjet ink.
Humectants [0276] If the color inkjet inks contain organic solvents or water, preferably the inks contain at least one humectant to prevent nozzle clogging due to its ability to reduce the evaporation rate of the ink.
[0277] Suitable humectants include glyceryl triacetate, N-methyl-2-pyrrolidone, glycerol, urea, thiourea, ethylene urea, alkyl urea, alkyl thiourea, dialkyl urea and dialkyl thiourea, diols such as ethanediols, propanediols, propanedriols, butane diols, glycols such as propylene glycol, polypropylene glycol, ethylene glycol, polyethylene glycol, diethylene glycol, tetraethylene glycol, and mixtures and derivatives thereof. Preferred humectants are triethylene glycol monobutyl ether, glycerol and 1,2-hexanediol. The humectant is preferably added to the inkjet ink formulation in an amount of from 0.1 to 40% by weight of the formulation, more preferably from 0.1 to 10% by weight of the formulation, and most preferably from about 4.0 to 6.0% by weight.
Other Additives [0278] The colored inkjet inks of an inkjet ink set according to the invention may contain other additives such as buffers, defoamers, pH adjusting agents, conductivity regulating agents, chelating agents, anti-rust agents, stabilizers to the action of light, dendrimers, polymers, crosslinkers, soluble electrolytes as electrical conductivity enhancers, masking agents and chelating agents, compounds for introducing additional safety properties, etc. Such additives may be included in the color inkjet inks of the inkjet ink set according to the invention, in any effective amount, if desired.
[0279] Compounds for introducing additional safety properties are selected from fluorescent compound, phosphorescent compound, thermochromatic compound, opalescent compound and magnetic particles. Suitable UV-fluorescent and phosphorescent compounds include Luminescent LUMILUX ™ pigments from HONEYWELL, UVITEX ™ OB from CIBA-GEIGY, KEYFLUOR ™ dyes and pigments from KEYSTONE, and fluorescent dyes from SYNTHEGEN.
[0280] The colored inkjet inks of an inkjet ink set according to the invention may further contain conductive or semi-conductive polymers such as polyanilines, polypyrroles, polythiophenes such as poly (ethylenedioxythiophene) (PEDOT), substituted or unsubstituted poly (phenylenovinylenes) (PPV ), such as PPV and MEH-PPV, polyfluoreins such as PF6, etc.
Preparation of pigmented inkjet inks [0281] Pigmented inkjet inks can be prepared by precipitating or milling the pigment in a dispersion medium in the presence of polymeric dispersants.
[0282] Mixing devices may include a pressure kneader, an open kneader, a planetary mixer, a mixer and a Dalton Universal Mixer. Suitable milling and dispersing equipment are ball mill, bead mill, colloid mill, high speed dispersant, two-roll mill, ball mill, paint flotation mixer and three-roll mill. Dispersions can also be obtained using ultrasonic energy.
[0283] Many different types of materials can be used as milling media, such as glass, ceramics, metals and plastics. In a preferred embodiment, the grinding media may comprise particles, preferably substantially spherical in shape, e.g. beads consisting essentially of a polymeric resin or yttrium stabilized zirconia beads. [0284] Each of the mixing, milling and dispersing processes is carried out using quenching to prevent heat buildup, whereas for radiation curable inkjet inks, these processes are carried out as much as possible under such lighting conditions in which is essentially excluded from actinic radiation.
[0285] The inkjet ink may contain more than one pigment, the inkjet ink may be made using separate dispersions for each pigment, or alternatively several pigments may be mixed and milled together when preparing the dispersion.
[0286] The dispersion process can be carried out in a continuous, stepwise or semi-continuous mode.
[0287] The preferred amounts and ratios of the ingredients in the milling will vary considerably depending on the specific and intended use. The components of the ground mixture include milling and milling agents. The milling contains pigment, polymeric dispersant and liquid carrier. For inkjet inks, the pigment usually occurs in milling in an amount of 1 to 50% by weight, excluding milling media. The weight ratio of pigment to polymeric dispersant is from 20: 1 to 1: 2. [0288] The milling time can vary considerably and depends on the pigment, mechanical means and selected residence conditions in the mill, and on the initial and desired final particle sizes, etc. Pigments dispersions with an average particle size below 100 nm can be prepared according to the invention.
[0289] After milling is completed, the milling media is separated from the milled product particles (both in dry and liquid dispersion form) using conventional separation techniques such as filtration, sieving, etc. Often, a screen is incorporated into the mill, e.g. in a ball grinder. The milled pigment concentrate is preferably separated from the milling media by filtration.
[0290] Generally, it is desirable to make the inkjet inks in the form of a concentrated mill, which is subsequently diluted to obtain the appropriate concentration for use in the inkjet printing system. This technique makes it possible to obtain larger amounts of colored ink using this equipment. By using dilution, the inkjet ink properties are adjusted to the desired viscosity, surface tension, color, shade, saturation density, and print area coverage for a particular application.
Spectral Separation Coefficient [0291] The SSF spectral separation coefficient has been found to be an excellent size characterizing a pigmented inkjet ink because it takes into account light absorption properties (e.g. wavelength for maximum absorbance λ ^ χ, shape of the absorption spectrum and absorbance value for ^<sub>ax</sub>), as well as properties regarding the quality and stability of the dispersion.
[0292] Measurement of absorbance for larger wavelengths gives an indication of the shape of the absorption spectrum. The quality of the dispersion can be estimated based on the phenomenon of light scattering caused by solid particles in solutions. When measuring transmittance, light scattering in pigment inks can be detected as increased absorbance at larger wavelengths than the maximum (peak) absorbance of the actual pigment. Dispersion stability can be estimated by comparing SSF before and after heat treatment, e.g. after holding for a week at 80 ° C.
[0293] The spectral separation factor SSF of the ink is calculated using the results obtained for the recorded spectrum of the ink solution or the jet printed image on the substrate and comparing the maximum absorbance to absorbance at the greater (reference) wavelength λ<sub>Γ</sub>θρ. The spectral separation factor is calculated as the ratio of maximum absorbance A<sub>max</sub> for absorbance A<sub>ref</sub> at reference wavelength.
anax
SSF = Aef [0294] SSF is an excellent tool for designing inkjet ink sets with a large range of colors. Currently, inkjet ink sets are often commercialized, and in these sets various inks are not sufficiently matched to each other. For example, the total absorption of all inks does not give complete absorption over the whole range of the visible spectrum, eg "holes" occur between the absorption spectra of dyes. Another problem is that one ink can absorb light in the range of another ink. The resulting range of colors for these inkjet ink sets is small or mediocre
Examples
Materials [0295] Unless otherwise specified, all materials used in the following examples were readily available from standard sources such as Aldrich Chemical Co. (Belgium) and Acros (Belgium).
The water used was deionized water.
BGA means butyl glycol acetate.
NMP means N-methylpyrrolidone.
Cinquasia ™ Magenta RT-355-D is a quinacridone pigment from CIBA SPECIALTY CHEMICALS.
PB15: 4 is the abbreviation used for Hostaperm<sup>TM</sup> Blue PBFS, cyan pigment (CI Pigment Blue 15: 4) from CLARIANT.
S35000 is the abbreviation used for SOLSPERSE<sup>TM</sup> 35,000, polyethyleneimine-polyester hyper-dispersant from
NOVEON.
Genorad ™ 16 is a polymerization inhibitor from RAHN AG. DPGDA means dipropylene glycol diacrylate from
SARTOMER.
Genocure ™ EPD means ethyl 4-dimethylaminobenzoate from
RAHN AG.
Genocure ™ TPO means 2,4,6-trimethylbenzoyldiphenylphosphine oxide from RAHN AG.
Genocure ™ PBZ means 4-phenylbenzophenone, a photoinitiator from RAHN AG.
BYK ™ UV3510 is a modified polydimethylsiloxane polyether which is a wetting agent from BYK
CHEMIE GMBH.
Oracal ™ 1640 stands for Oracal ™ Blanc 1640 Print Vinyl, an adhesive polyvinyl chloride backing material from ANTALIS.
Rayoart ™ CGS 92 is a high gloss film, coated on both sides, transparent, biaxially oriented polypropylene from INNOVIA FILMS.
SeeMee ™ Standard Easy stands for Seemee ™ backlit standard easy, PVC coated on both sides from VERSEIDAG-INDUTEX GMBH.
Fasson ™ MC Primecoat S2000N stands for FASSON ™ MC Primecoat / S200ON / HF80, white, machine-coated on one side, substrate for wood-free paper for printing from AVERY DENNIZON.
Pripack Classic means Pripack classic blanc et couleur (Pripack classic white color), extruded polypropylene film from ANTALIS.
Biprint 650 gr means Biprint blanc / couleur, corona treated, polypropylene plate from ANTALIS.
Measurement methods
1. SSF measurement [0296] The spectral separation factor of SSF of ink was calculated using the results obtained for the recorded spectrum of the ink solution and comparing the maximum absorbance to absorbance at the reference wavelength. The choice of this reference wavelength depends on the pigment (s) used:
- if the color ink has a maximum absorbance of A<sub>max </sub>between 400 and 500 nm, then absorbance A<sub>ref</sub> must be determined at a reference wavelength of 600 nm,
- if the color ink has a maximum absorbance of A<sub>max </sub>between 500 and 600 nm, then absorbance A<sub>ref</sub> must be determined at a reference wavelength of 650 nm,
- if the color ink has a maximum absorbance of A<sub>max </sub>between 600 and 700 nm, then absorbance A<sub>ref</sub> must be determined at a reference wavelength of 830 nm.
[0297] Absorbance was determined in transmittance units using a Shimadzu UV-2101 PC double beam spectrophotometer. The ink was diluted to give a pigment concentration of 0.002%. For fuchsin ink, the ink was diluted to obtain a pigment concentration of 0.005%.
The spectrophotometric measurement of the UV-VIS-NIR absorption spectrum of the diluted ink was carried out in transmittance mode using a double beam spectrophotometer using the settings shown in Table 1. Quartz cuvettes with an absorbing layer length of 10 mm were used and water was selected as the reference liquid.
Table 1
<td>Operating mode</td><td>absorbance</td>
<td>Length range wave</td><td>240-900 nm</td>
<td>Width slots</td><td>2.0 nm</td>
<td>Space scan</td><td>1.0 nm</td>
<td>Speed scan</td><td>fast (1165 nm / minute)</td>
<td>Detector</td><td>photomultiplier (UV-VIS)</td>
[0298] For effective pigmented inkjet inks exhibiting a narrow absorption spectrum and high maximum absorbance, the SSF value is at least 30.
2. Average Particle Size [0299] The average pigment particle size in the non-aqueous inkjet ink was determined using a Brookhaven ™ Instruments Particle Sizer B190plus apparatus based on the principle of dynamic light scattering. The ink or dispersion was diluted with ethyl acetate to a pigment concentration of 0.002% by weight. The B190plus measurement settings were as follows: 5 series at 23 ° C, 90 ° angle, 635 nm wavelength and graphics = correction function.
[0300] Inkjet ink with good properties (spraying properties and print quality) should have an average dispersed particle size below 200 nm, preferably below 150 nm.
3. Dispersion stability [0301] Dispersion stability was estimated by comparing the particle size before and after heat treatment over 7 days at 83 ° C. Pigmented inkjet inks showing good dispersion stability show an increase in the average particle size after heat treatment of less than 10%.
4. Viscosity [0302] The viscosity of the inkjet inks was measured using a Brookfield DV-II + viscometer at 25 ° C and a shear rate of 4 rpm using a CPE 40 spindle.
5. Dot size [0303] Dot size was measured on a Cell Check CNCSLS apparatus (from M-Service & Gerate - Peter Muller, Germany) using a 150x microscope lens attached to a WAT-202B camera (from Watec Co., Ltd. Japan). The average of five dot size measurements was calculated using the Metric version 8.02 Live software (from M-Service & Gerate - Peter Muller, Germany).
6. Cure Speed [0304] The percentage of maximum lamp performance was taken as a measure of the cure speed, the lower the numerical value, the faster the cure speed. The sample was considered completely cured when scratching with the Q-tip caused no visual damage.
7. Surface energy of the substrate material [0305] The Owens-Wendt equation was used to calculate the surface energy of the substrate material σ<sub>3</sub> in the same manner as disclosed in US Pat. Ser. United States No. 2005190245 (AGFA).
8. Surface tension [0306] The surface tension of the inkjet inks was measured using a KRUSS K9 tensiometer at 25 ° C after 60 seconds.
9. Adhesion [0307] Ink adhesion was tested by visual inspection of a mesh structure that was manually scratched using a sharp needle tip on a UV cured ink layer. The grade was awarded according to the degree of damage to the ink layer.
Criterion:
= not damaged = very slightly damaged = slightly damaged = significantly damaged = very damaged.
10. Same color and density [0308] In the context of the present invention, the following procedure was used to determine whether two ink mixtures have the same color and density.
[0309] Starting from the ink formulation that was used in the printer, 1: 1000 by weight dilutions were prepared. It is clear that the solvent used for dilution must be compatible with the ink dispersion, i.e. the solvent should be chosen so as to maintain the chemical and physical stability of the dispersion, as otherwise color changes may occur due to additional light scattering, e.g. for this reason that agglomeration of particles may occur. Preferably, the dilution solvent is selected from one or more liquid ink components. In the examples below, DPDGA was used as the dilution solvent.
[0310] Light Τ transmission measurements by diluted ink dispersions were performed using a spectrophotometer. The measurements were based on the following geometry: direct lighting and diffuse integration. An example of such a spectrophotometer is the Lambda 900 double beam spectrophotometer from Perkin Elmer, realizing the measurement geometry Τ (8 / d) according to ASTM E179-96. [0311] Quartz cuvettes with a 10 mm optical path length were filled with diluted inks and then placed in contact with the entry port of the integrating sphere. The same quartz cuvettes filled with the pure solvent used were used for reference measurements. The light transmission spectra of the diluted inks were divided by the light transmission spectra of the reference measurement to correct the measurement results due to the dilution solvent and quartz cuvette. Based on these spectra, the CIE L * a * b * color space coordinates were calculated according to ASTM E308-01 based on the CIE 1931 model of a standard observer (in a narrow field of view - 2 degrees) and using the illuminant D50 (daylight standard for printed materials). From the CIE L * a * b * coordinates, the CIE ΔE2000 color difference was calculated using industry-specific K parameters<sub>L</sub>, K<sub>C</sub> and K<sub>H</sub> regulated to unity (1).
[0312] Due to the area of inkjet applications for which this invention is intended, two ink mixtures A and B are considered to have different color and density when CIE E2000> 5.0 for a given observer and illuminant was obtained, i.e. no spectral matching is required. [0313] If the color difference CIE ΔE2000 between ink mixture A and ink mixture B was greater than 5.0, new color matching in inkjet systems in color control categories is usually required, while differences less than 2.0 can only be compensated by new linearization of the printer. In this sense, two ink mixtures A and B with a color difference in a CIE ΔE2000 pair less than or equal to 2.0 are considered to have the same color and density.
[0314] For more demanding printing applications, the color difference CIE ΔE2000 less than or equal
1.5 is required for the same color and density. In an even more restrictive colorimetric approach, the same color and color density is obtained if the color difference CIE ΔE2000 is less than or equal to 1.0.
[0315] Literature reference:
- ASTM D2244-02 Standard Practice for Calculation of Color Tolerances and Color Differences from Instrumentally measured Color Coordinates
- ASTM E179-96 (2003) Standard Guide for Selection of Geometric Conditions for Measurements of Reflection and Transmission Properties of Materials
- ASTM E308-01 Standard Practice for Computing the Colors of Objects by Using the CIE system
Example 1 [0316] This example illustrates how the same dot size was obtained on different substrate materials using two curable inkjet inks with different surface tension values.
Preparation of the inkjet ink [0317] The concentrated P1 pigment dispersion was prepared according to the data given in Table 2.
Table 2
<td>weight%:</td><td>P1</td>
<td>Cinquasia ™ Magenta RT-355-D</td><td> 20,0</td>
<td>Solsperse ™ 35000</td><td> 20,0</td>
<td>Genorad ™ 16</td><td> 1,0</td>
<td>DPGDA</td><td> 59,0</td>
[0318] A concentrated P1 pigment dispersion was prepared by mixing 360.0 g of Cinquasia ™ Magenta RT-355-D pigment, 36.0 g of a 50% solution of the Genorad ™ 16 inhibitor in DPGDA and 1028.6 g of a 35% solution of the polymeric dispersant Solsperse ™ 35,000 in DPGDA for 30 minutes using a DISPERLUX ™ Laboratory Dissolver YELLOW075 mixer from DISPERLUX SARL, Luxembourg. The milling mixture was then milled at a rotational speed of 13 m / s and a flow rate of 0.6 l / min using cooling using NETZSCH ™ LABSTAR1, at 54.4% by volume filling with yttrium stabilized zirconia balls with a diameter of 0, 4 mm ("highly abrasion resistant zirconia grinding media" from TOSOH Co.) and using a residence time of 85 minutes. After milling, the dispersion was separated from the beads using a filter cloth. The concentrated P1 pigment dispersion had an average particle size of 96 nm and an SSF of 60.
[0319] Curable fuchsin inkjet INK-1 ink was prepared from the concentrated P1 pigment dispersion by adding the remaining ingredients, stirring at 20 ° C to obtain the composition as shown in Table 3.
Table 3
<td>% by weight</td><td>INK-1</td>
<td>P1 dispersion</td><td> 25,00</td>
<td>DPGDA</td><td> 49, 00</td>
<td>Genocure<sup>TM</sup> TPO</td><td> 12,50</td>
<td>Genocure<sup>TM</sup> PBZ</td><td> 6,25</td>
<td>Genocure<sup>TM</sup> EPD</td><td> 6, 25</td>
<td>Genorad<sup>TM</sup> 16</td><td> 1,00</td>
Printing and estimation [0320] Table 4 shows five different substrate materials and their surface energy, which were selected for this example.
Table 4
<td>Material ground</td><td>trade name</td><td>Energy Surface (MJ / m<sup>2</sup>)</td>
<td>SUB-1</td><td>Oracal 1640</td><td> 39, 0</td>
<td>SUB-2</td><td>Rayoart CGS 92</td><td> 41,8</td>
<td>SUB-3</td><td>SeeMee Standard Easy</td><td> 45,6</td>
<td>SUB-4</td><td>Fasson MC Primecoat S2000N</td><td> 46,7</td>
<td>SUB-5</td><td>Pripack Classic</td><td> 60, 0</td>
[0321] Five SUB-1 to SUB-5 substrate materials were printed using mixtures of LIQ-1 and LIQ-2 colorless liquids according to Table 5 with curable fuchsin ink for INK-1 inkjet printer.
Table 5
<td>% by weight</td><td>LIQ-1</td><td>LIQ-2</td>
<td>DPGDA</td><td> 85, 00</td><td> 100,00</td>
<td>Bull<sup>TM</sup> UV 3510</td><td> 15,00</td><td> —</td>
[0322] Several ink mixtures were prepared by mixing the curable inkjet ink INK-1 and the colorless liquids LIQ-1 and LIQ-2 according to table 6 to obtain the desired size of the printed dot of
100 μη.
[0323] The ink mixtures were printed using a specially designed printer equipped with an UPH ™ print head attached from AGFA, with a distance between the nozzle plate and the ink receiving material of 1.0 mm. The inks were sprayed at 5 dpd with a resolution of 360x360 dpi and cured on an ongoing basis using a DPL 120 W irradiation lamp 50 W at 400 mm / s. Final curing was carried out by passing the sprayed image twice at a speed of 330 mm / s under 50 W irradiation. The time from spraying to curing was 1.3 seconds. The distance between the UV lamp and the ink-receiving material was 2.2 mm. The spray temperature was 45 ° C.
[0324] The dot sizes obtained for the curable ink mixtures are given in Table 6.
Table 6
<td>Material</td><td colspan="3">A mixture of inks</td><td>Tension</td><td>Size</td>
<td>ground</td><td></td><td></td><td></td><td>surface</td><td>dots</td>
<td></td><td>wt% INK-1</td><td>% LIQ-1 by weight</td><td>wt% LIQ-2</td><td>(MN / m)</td><td>(Μια)</td>
<td>SUB-1</td><td> 80, 00</td><td> 0,33</td><td> 19, 67</td><td> 25, 7</td><td> 100</td>
<td>SUB-2</td><td> 80, 00</td><td> 6, 67</td><td> 13,33</td><td> 22,4</td><td> 97</td>
<td>SUB-3</td><td> 80, 00</td><td> 0, 03</td><td> 19, 97</td><td> 32,3</td><td> 99</td>
<td>SUB-4</td><td> 80, 00</td><td> 0, 67</td><td> 19, 33</td><td> 25, 7</td><td> 100</td>
<td>SUB-5</td><td> 80, 00</td><td> 13,33</td><td> 6, 67</td><td> 21,8</td><td> 99</td>
[0325] Very consistent image quality was obtained using the ink mixtures according to Table 6 on SUB-1 to SUB-5 substrate materials, since all the ink mixtures gave dots of approximately 100 Pm. It can be seen that there is no apparent relationship between the surface tension of the ink mixture and the surface energy of the substrate material on which it is printed. It should also be obvious that it is not possible to obtain the same size of printed dot using a single ink mixture. This is exemplified in Table 8, where the ink mixture according to Table 6 used for printing on SUB-2 substrate material was printed on other SUB-1 and SUB-3 to SUB20 5 substrate materials. The wide range of printed dot sizes obtained for this curable ink mixture shown in table 7.
Table 7
<td>Material ground</td><td colspan="3">Ink mixture</td><td>Size dots</td>
<td></td><td>wt% INK-1</td><td>% LIQ-1 by weight</td><td>wt% LIQ-2</td><td></td>
<td>SUB-1</td><td> 80, 00</td><td> 6, 67</td><td> 13,33</td><td> 164</td>
<td>SUB-3</td><td> 80, 00</td><td> 6, 67</td><td> 13,33</td><td> 110</td>
<td>SUB-4</td><td> 80, 00</td><td> 6, 67</td><td> 13,33</td><td> 119</td>
<td>SUB-5</td><td> 80, 00</td><td> 6, 67</td><td> 13,33</td><td> 99</td>
Example 2 [0326] This example illustrates a printing test estimating the dot size on SUB-4 and SUB-6 substrate materials (biprint 650 gr), using a series of ink mixtures based on the same curable ink for INK-1 and colorless inkjet printers LIQ-1 and LIQ-2 liquids as per the example
1.
Printing and estimation [0327] The obtained dot sizes for ink mixtures 1 to 9 of curable inkjet ink INK-1 and colorless liquids LIQ-1 and LIQ-2 printed in the same way as in Example 1 are shown in Table 8.
Table 8
<td colspan="4">Ink mixture</td><td rowspan="2">Tension surface (MN / m)</td><td rowspan="2">Size dots on SUB-4 (Μια)</td><td rowspan="2">Size dots on SUB-6</td>
<td>No.</td><td>ABOUT. % weight INK-1</td><td>ABOUT. % weight LIQ-1</td><td>ABOUT. % weight LIQ-2</td>
<td> 1</td><td> 80, 00</td><td> 0, 00</td><td> 20, 00</td><td> 35, 1</td><td> 105</td><td> 76</td>
<td> 2</td><td> 80, 00</td><td> 0, 03</td><td> 19, 97</td><td> 32,3</td><td> 95</td><td> 68</td>
<td> 3</td><td> 80, 00</td><td> 0, 07</td><td> 19, 93</td><td> 27,4</td><td> 96</td><td> 71</td>
<td> 4</td><td> 80, 00</td><td> 0,33</td><td> 19, 67</td><td> 25, 7</td><td> 100</td><td> 69</td>
<td> 5</td><td> 80, 00</td><td> 0, 67</td><td> 19, 33</td><td> 25, 7</td><td> 100</td><td> 70</td>
<td> 6</td><td> 80, 00</td><td> 3,33</td><td> 16, 67</td><td> 23, 0</td><td> 112</td><td> 73</td>
<td> 7</td><td> 80, 00</td><td> 6, 67</td><td> 13,33</td><td> 22,4</td><td> 119</td><td> 87</td>
<td> 8</td><td> 80, 00</td><td> 13,33</td><td> 6, 67</td><td> 21,8</td><td> 123</td><td> 158</td>
<td> 9</td><td> 80, 00</td><td> 20, 00</td><td> 0, 00</td><td> 21,8</td><td> 124</td><td> 175</td>
[0328] Based on the results presented in Table 8, it can be seen that for a dot size of e.g.
120 μm ink mixture No. 7 can be used on SUB-4 substrate material. On SUB-6 substrate material (biprint 650 gr), the ink mixture for the printed dot size of 120 μm is between ink mixtures No. 7 and No. 8. To determine the exact composition of the ink mixture required for SUB-6, a second dot size test may be performed in the range between ink mixtures No. 7 and No. 8, or it may be determined by plotting the dot size from the weight% colorless liquid LIQ-1. Based on this chart, it was found that 9.60 wt.% LIQ-1, 10.40 wt.% LIQ-2 and 80 wt.% INK-1 should be used, based on the total weight of the ink mixture.
[0329] The dot size data in Table 8 also clearly show that the two substrate materials react quite differently to the ink mixtures. These obtained dot size data for specific ink mixtures can be stored in a data library for future use of the same substrate material. Thus, the library increases production capacity in an industrial printing environment because there is no need to allocate additional time to adjust the ink and substrate material to achieve the desired ink spread on the substrate material.
Example 3 [0330] This example illustrates how an improvement in adhesion can be obtained for an inkjet ink mixture and two colorless liquids which, when prepared normally, may exhibit unacceptable dispersion stability.
Inkjet ink preparation [0331] A concentrated P2 pigment dispersion was prepared by mixing 3750 g of PB15: 4 pigment and 9375 g of a 40% solution of S35000 polymeric dispersant in BGA for 30 minutes using a DISPERLUX mixer<sup>TM</sup> Dissolver from
DISPERLUX SARL, Luxembourg. The dispersion was then milled using cooling in a DYNOMILL ECM Poly mill from Willy A. Bachofen AG Machinenfabrik filled with 20.521 kg yttrium stabilized zirconia balls with a diameter of
0.4 mm ("highly abrasion resistant zirconia grinding media" from TOSOH Co.) for 4 hours and 23 minutes (residence time 40 minutes) at a rotation speed of 14.7 m / s.
[0332] An INK-2 inkjet ink was prepared by diluting the P2 pigment dispersion using BGA to a concentration of 5.20% by weight PB15: 4 based on the total weight of the ink. The INK-2 inkjet ink had an average particle size for PB15: 4 of 137 nm. No increase in particle size was observed after heat treatment of INK-2 ink for 7 days at 83 ° C.
[0333] Similarly, inkjet inks INK-3 to INK-5 were obtained by diluting the pigment pigment dispersion using a mixture of BGA and NMP according to Table 9. An increase in the average particle size was observed for INK-4 and INK-5 inks containing a larger amount N-methylpyrrolidone.
Table 9
<td rowspan="2">Mascara for printer streaming</td><td colspan="3">Ink composition</td><td rowspan="2">% growth average particle size after 7 days at temperature 83 ° C</td>
<td>% by weight P2</td><td>% by weight BGA</td><td>% by weight Virgin Mary</td>
<td>INK-2</td><td> 50, 0</td><td> 50, 0</td><td> —</td><td> 0%</td>
<td>INK-3</td><td> 25, 0</td><td> 65, 0</td><td> 10, 0</td><td> 0%</td>
<td>INK-4</td><td> 25, 0</td><td> 55, 0</td><td> 20, 0</td><td> 16%</td>
<td>INK-5</td><td> 25, 0</td><td> 45, 0</td><td> 30, 0</td><td> 24%</td>
[0334] Three ink mixtures were prepared by mixing INK-2 in different ratios with LIQ-3 (BGA) and LIQ-4 (NMP) according to table 10.
Table 10
<td>Mixture</td><td colspan="3">Ink mixture composition</td>
<td>ink</td><td></td><td></td><td></td>
<td></td><td>% by weight</td><td>% by weight</td><td>% by weight</td>
<td></td><td>INK-2</td><td>LIQ-3</td><td>LIQ-4</td>
<td>MIX-1</td><td> 50, 0</td><td> 40, 0</td><td> 10, 0</td>
<td>MIX-2</td><td> 50, 0</td><td> 30, 0</td><td> 20, 0</td>
<td>INK-3</td><td> 50, 0</td><td> 20, 0</td><td> 30, 0</td>
[0335] Table 11 gives an overview of the various ink compositions, along with the results of dispersion and adhesion stability on a vinyl backing material, Avery MPI 3000.
Table 11
<td rowspan="2">ink</td><td colspan="4">Ink composition</td><td rowspan="2">% growth dimension particles after 7 days in temperature 83 ° C</td><td rowspan="2">Adhesion</td>
<td>PB15: 4</td><td>S35000</td><td>BGA</td><td>Virgin Mary</td>
<td>INK-2</td><td> 5, 2</td><td> 5, 2</td><td> 89, 6</td><td> —</td><td> 0%</td><td> 4</td>
<td>INK-3</td><td> 2, 6</td><td> 2, 6</td><td> 84, 8</td><td> 10</td><td> 0%</td><td> 3</td>
<td>INK-4</td><td> 2, 6</td><td> 2, 6</td><td> 74, 8</td><td> 20</td><td> 16%</td><td> 1</td>
<td>INK-5</td><td> 2, 6</td><td> 2, 6</td><td> 64, 8</td><td> 30</td><td> 24%</td><td> 1</td>
<td>MIX-1</td><td> 2, 6</td><td> 2, 6</td><td> 84, 8</td><td> 10</td><td> 0%</td><td> 3</td>
<td>MIX-2</td><td> 2, 6</td><td> 2, 6</td><td> 74, 8</td><td> 20</td><td> 0%</td><td> 1</td>
<td>MIX-3</td><td> 2, 6</td><td> 2, 6</td><td> 64, 8</td><td> 30</td><td> 0%</td><td> 1</td>
[0336] Higher concentrations of N-methylpyrrolidone solvent have been found to improve the adhesion of the ink to the vinyl substrate material. In the shelf life study, simulated by heat treatment for 7 days at 83 ° C, INK-4 and INK-5 inks made using NMP, an increase in the size of the pigment particles was found. The addition of the NMP solvent as LIQ-4 just before spraying the ink prevented the increase in particle size while improving the adhesion.
Example 4 [0337] This example illustrates the effect of not using a fixed ratio of content by weight percent of colored inkjet ink to content by weight percent of two or more colorless liquids. Dilution of the color inkjet ink with increasing amounts of colorless liquid becomes noticeable in the printed image when the ink mixture is obtained, if no color management adaptation is performed.
[0338] As already mentioned, two ink mixtures are considered to have different color and density when the CIE ΔE2000 value is greater than 5.0. For most inkjet applications, such as large format inkjet, differences in the color and density of two inks may be acceptable if the CIE ΔE2000 value is less than or equal to 2.0. For more demanding inkjet applications, usually judged by the viewing distance of the image, the CIE ΔE2000 value should be smaller.
[0339] The CIE ΔE2000 value was determined for mixtures of INK-1 fuchsin ink according to example 1 with DPGDA. The results are given in Table 12
Table 12
<td>% dilution of INK-1 using DPGDA</td><td>CIE ΔE2000</td>
<td> 0</td><td> 0, 0</td>
<td> 5</td><td> 1,0</td>
<td> 10</td><td> 1,9</td>
<td> 15</td><td> 2,8</td>
<td> 20</td><td> 3,5</td>
<td> 25</td><td> 4,4</td>
[0340] When using inkjet printing that requires a CIE ΕΕ2000 value less than 2.0, a 10% dilution may be acceptable for cyan ink.
However, for applications that require high-quality inkjet printing, blending errors of two or more inks should be less than 5%, i.e. CIE ΔΕ2000 should be less than 1.0.
Contents3
108 members in 30 offices
Priority claims2
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| 06126903 | European Patent Office (EPO) | A | |
| EP20060126903 | – | – | – |
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Numbers
- Publication, DOCDB
- 1935652
- Publication, EPODOC
- PL1935652T
- Application
- 126903
- Application, DOCDB
- 06126903
- Application, EPODOC
- PL20060126903T
Titles2
- English
- Inkjet Printing methods and ink sets
- Polish
- Sposób drukowania strumieniowego i zestawy tuszów
Classification
- CPC, 14
- B41J2/175
- B41J2/015
- B41J2/17503
- B41J2/2107
- B41J2/211
- B41M5/0023
- B41M7/0072
- C09D11/101
- C09D11/322
- C09D11/40
- B41J2/2114
- B41J2/2117
- G01D11/00
- B41J2/01
- IPC, 4
- B41J2 21
- B41M5 00
- C09D11 00
- C09D11 10