Ink composition for inkjet recording

0001Embodiments of the present invention relate to ink composition for inkjet recording.

0002The inkjet recording method is a method of printing by flying minute droplets of ink and adhering them to a recording medium. This method is characterized in that high-resolution, high-quality images can be printed at high speed. The inkjet recording method is used in plain paper printing printers used in offices and industrial printers such as label printers.

0003In recent years, as inkjet inks used in industrial printers, those using pigment-based colorants have been increasing in place of those using dye-based colorants. This is because the ink using the pigment is superior in water resistance and light resistance to the ink using the dye.

<p num="0004"><patcit num="1"><text>Japanese Unexamined Patent Publication No. 11-199811</text></patcit><patcit num="2"><text>Japanese Unexamined Patent Publication No. 2003-345080</text></patcit><patcit num="3"><text>Japanese Unexamined Patent Publication No. 2001-081369</text></patcit></p>

<p num="0005"> The problem to be solved by the present invention is that an ink composition containing a pigment is used and has excellent adhesion to a non-penetrating recording medium without increasing the labor required for maintenance of the inkjet recording apparatus. The purpose is to make it possible to form a print layer.</p>

<p num="0006"> According to the embodiment, the ink composition for inkjet recording is water.<u style="single">And gu</u>Dispersion medium containing recall ether<u style="single">The glycol ether is a dispersion medium containing only tripropylene glycol monomethyl ether.</u>And core-shell particles comprising a pigment, a core made of a hydrophobic acrylic resin, and a shell made of at least one of an aqueous urethane resin and an acrylic graft aqueous urethane resin.<u style="single">In the ink composition for inkjet recording, the proportion of the tripropylene glycol monomethyl ether in the ink composition is in the range of 0.5 to 10% by mass, and the proportion of the core-shell particles in the ink composition is 1. Within the range of 30% by mass</u>To. <u style="single">According to the embodiment, the inkjet recording apparatus is an inkjet recording apparatus including an ink cartridge and an ink composition contained in the ink cartridge, and the ink composition is a dispersion containing water and glycol ether. As a medium, the glycol ether is a dispersion medium containing only tripropylene glycol monomethyl ether, a pigment, a core made of a hydrophobic acrylic resin, and a shell made of at least one of an aqueous urethane resin and an acrylic graft aqueous urethane resin. The proportion of the tripropylene glycol monomethyl ether in the ink composition is in the range of 0.5 to 10% by mass, and the proportion of the core-shell particles in the ink composition is 1 to 30. It is in the range of mass%.</u></p>

0007<figref num="1">The figure which shows typically an example of the inkjet recording apparatus which can be used for the inkjet recording using the ink composition which concerns on embodiment.</figref>

0008The inkjet recording ink composition according to the embodiment and the recording method using the ink composition will be described below.

0009&lt;Ink composition for inkjet recording&gt; The inkjet recording ink composition according to the embodiment contains a dispersion medium, a pigment, and core-shell particles. The pigment and core-shell particles and the dispersion medium form a suspension or emulsion. This ink composition may further contain an additive such as a pigment dispersant.

0010This ink composition has a viscosity suitable for ejection from the head nozzle of an inkjet recording device, for example, an inkjet printer. According to one example, this ink composition has a viscosity of 20 mPa · s or less at 25 ° C. Each component of this ink composition will be described below.

0011[Pigment] The pigment is dispersed in the dispersion medium. As the pigment, either an inorganic pigment or an organic pigment may be used.

0012Examples of the inorganic pigment include titanium oxide, aluminum pigment and iron oxide. These inorganic pigments may be used in combination with carbon black produced by known methods such as a contact method, a furnace method, and a thermal method.

0013Examples of organic pigments include azo pigments including azo lake pigments, insoluble azo pigments, condensed azo pigments, and chelate azo pigments; phthalocyanine pigments, perylene pigments, perinone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, thioindigo pigments, and isoind. Polycyclic pigments such as linone pigments and quinophthalone pigments; dye chelates such as basic dye chelate and acidic dye chelate; nitro pigments; nitroso pigments; or aniline black can be used.

0014When obtaining a yellow ink composition, it is preferable to use Pigment Yellow 155 as the pigment.

0015Pigment Yellow 74 is mainly used as the yellow pigment in the ink composition for inkjet recording. It is considered that this is because Pigment Yellow 74 is excellent in color development and dispersion stability. However, Pigment Yellow 74 has low light resistance. Therefore, the printed matter produced by using the ink composition containing Pigment Yellow 74 is not suitable for outdoor use.

0016Pigment Yellow 155 has sufficient color development and dispersion stability, and also has excellent light resistance. Therefore, the ink composition containing Pigment Yellow 155 is particularly suitable for producing printed matter used outdoors.

0017Only one type of pigment can be used. Alternatively, two or more kinds of pigments may be used. For example, Pigment Yellow 155 may be used as the main pigment, and one or more other pigments may be used as the auxiliary pigment. Auxiliary pigments can be used to adjust the color tone.

0018As the pigment, a self-dispersed pigment may be used. The self-dispersing pigment is a pigment in which the pigment is surface-treated so that it can be dispersed in water or the like without a dispersant. Here, the surface treatment is, for example, a vacuum plasma treatment, a diazo coupling treatment, or an oxidation treatment. By this surface treatment, for example, at least one functional group of a carbonyl group, a carboxyl group, a hydroxyl group, and a sulfone group or a salt thereof is bonded to the pigment. For example, the functional group or a molecule containing the functional group is grafted on the surface of the pigment. As a result, the affinity of the pigment for water and the like is enhanced, and the pigment can be dispersed in water and the like without a dispersant.

0019When a self-dispersing pigment is used, a pigment dispersant described later may be used in combination. As described above, the self-dispersing pigment can be dispersed in a dispersion medium such as water without a dispersant. However, when a highly hydrophobic substance or core-shell particles are present in such a dispersion medium, the particle size of the pigment may increase or the pigment may aggregate and settle over time. .. When a self-dispersing pigment and a pigment dispersant are used in combination, the particle size of the pigment increases and the pigment aggregates over time even when a highly hydrophobic substance or core-shell particles are present in the dispersion medium. And sedimentation can be suppressed.

0020The average particle size of the pigment is, for example, in the range of 30 to 300 nm, typically in the range of 50 to 200 nm.

0021The average particle size of the pigment can be measured using a particle size distribution meter using a dynamic light scattering method. Examples of the particle size distribution meter include HPPS (Malvern).

0022The proportion of the pigment in the ink composition is preferably in the range of 2 to 15% by mass, more preferably in the range of 3 to 10% by mass. Decreasing this ratio makes it difficult to achieve high image density. Increasing this ratio may reduce the storage stability of the ink composition and may cause inconvenience in ink ejection.

0023[Core shell particles] The core-shell particles are dispersed in the dispersion medium.

0024Core-shell particles include a core and a shell surrounding it. The core is made of hydrophobic acrylic resin. The shell is made of at least one of a water-based urethane resin and an acrylic graft water-based urethane resin.

0025The core-shell particles serve as a fixing agent. The core-shell particles make it possible to form a print layer having excellent adhesion to the recording medium even when the recording medium is impermeable. The core-shell particles also improve the scratch resistance of the print layer.

0026The proportion of core-shell particles in the ink composition is preferably in the range of 1-40% by mass, more preferably in the range of 1-30% by mass, and in the range of 3-20% by mass. Is more preferable.

0027The core-shell particles exist, for example, as a dispersed phase of an aqueous resin emulsion in which the continuous phase is water until mixed with the pigment. The ink composition is obtained, for example, by mixing this aqueous resin emulsion with other components such as pigments.

0028[Dispersion medium] The dispersion medium is an aqueous solution containing water and glycol ether. The glycol ether used here has a boiling point of 220 ° C. or higher. As such glycol ether, for example, diethylene glycol monoisobutyl ether, diethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, or triethylene glycol monobutyl ether can be used.

0029Since these glycol ethers have a high boiling point, they are difficult to volatilize. In addition, these glycol ethers are excellent in resolubility of the emulsion or suspension. Therefore, when this ink composition is used, it is possible to suppress the drying of the ink composition in the vicinity of the nozzle of the inkjet head. Therefore, the labor required for the maintenance of the inkjet recording device can be reduced.

0030The proportion of the glycol ether in the dispersion medium is preferably in the range of 0.5 to 15% by mass, more preferably in the range of 0.5 to 10% by mass, and further preferably in the range of 0.5 to 5% by mass. is there. When this ratio is small, the above effect is small. Increasing this ratio may reduce fixability.

0031(Wetting agent) The dispersion medium can further contain a wetting agent that prevents the ink composition from drying out. As the wetting agent, a water-soluble liquid wetting agent, for example, a polyhydric alcohol, a nitrogen-containing heterocyclic compound, amines, or a sulfur-containing compound can be used. These liquid wetting agents also have an effect of enhancing the dispersion stability of the pigment in the ink composition.

0032Examples of polyhydric alcohols include ethylene glycol, diethylene glycol, triolethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, 1,5-pentanediol, 1,6-hexanediol, glycerin, and 1,2,6-hexane. Triol, 1,2,4-butanetriol, 1,2,3-butanetriol, and 3-methyl-1,3,5-pentanetriol can be mentioned.

0033Examples of the nitrogen-containing heterocyclic compound include N-methyl-2-pyrrolidone, N-hydroxyethyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethylimidazolidinone, and ε-caprolactam.

0034Examples of amines include monoethanolamine, diethanolamine, triethanolamine, monoethylamine, diethylamine, and triethylamine.

0035Examples of the sulfur-containing compound include dimethyl sulfoxide, sulfolane, thiodiethanol and the like.

0036Liquid wetting agents other than polyhydric alcohols, nitrogen-containing heterocyclic compounds, amines and sulfur-containing compounds include, for example, propylene carbonate, ethylene carbonate, and γ-butyrolactone.

0037Among these wetting agents, glycerin has a high water retention and a high boiling point as compared with other wetting agents, so that it is difficult to volatilize. Therefore, it is preferable to use glycerin as at least a part of the wetting agent.

0038The concentration of the wetting agent in the ink composition is preferably 1 to 40% by mass, more preferably 2 to 40% by mass.

0039Only one type of wetting agent may be used, or two or more types may be used in combination. Further, in order to further improve the wetting effect, the above-mentioned liquid wetting agent may be used in combination with a solid wetting agent such as urea, thiourea, or ethylene urea. The ratio of the solid wetting agent to the total wetting agent is preferably 30% by mass or less.

0040(Pigment dispersant) The dispersion medium can further contain a pigment dispersant (or a discharge stabilizer). The pigment dispersant is, for example, a polymer dispersant or a surfactant.

0041Examples of the polymer dispersant include polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, acrylic acid-acrylonitrile copolymer, acrylic acid-acrylic acid ester copolymer, styrene-acrylic acid copolymer, and styrene-methacrylic acid copolymer. Examples include polymers and styrene-maleic acid copolymers.

0042Examples of the surfactant include fatty acid salts, higher alkyl dicarboxylates, higher alcohol sulfates, higher alkyl sulfonates, condensates of higher fatty acids and amino acids, sulfocarbonate ester salts, naphthenates, and liquid fats. Examples thereof include anion surfactants such as oil sulfate esters, alkylallyl sulfonates, polyoxyethylene alkyl ether carboxylates, polyoxyethylene alkyl ether sulfates, and polyoxyethylene alkyl ether ether phosphates.

0043As the surfactant, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, and acetylene glycols may be used. ..

0044Among these, polyoxyethylene anionic surfactants such as polyoxyethylene alkyl ether carboxylate, polyoxyethylene alkyl ether sulfate, and polyoxyethylene alkyl ether phosphate are preferable. When such a surfactant is used as a pigment dispersant, it is possible to suppress an increase in the particle size of the pigment and aggregation and precipitation of the pigment with the passage of time. Therefore, very good storage stability can be achieved.

0045The amount of the pigment dispersant is preferably in the range of 1 to 50% by mass, more preferably in the range of 5 to 40% by mass with respect to the pigment.

0046(Other additives) The dispersion medium can further contain other additives. For example, the dispersion medium may further contain a surface tension modifier.

0047As the surface tension adjusting agent, the above-mentioned nonionic surfactant may be used. Examples of the surface tension adjusting agent include polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, and acetylene glycols. Further, as the surface tension adjusting agent, a silicon-based surfactant or a fluorine-based surfactant may be used.

0048The concentration of the surface tensioning agent in the ink composition is preferably in the range of 0.5 to 3% by mass.

0049The dispersion medium may further contain a pH regulator or an antiseptic or antifungal agent. Examples of the pH adjuster include sodium hydroxide, potassium hydroxide, potassium dihydrogen phosphate, and disodium hydrogen phosphate.

0050Examples of antiseptic or antifungal agents include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium hydroacetate, and 1,2-dibenzosothiazolin-3-one. Can be mentioned.

0051&lt;Recording method&gt; For inkjet recording using the above-mentioned ink composition, for example, the inkjet recording apparatus shown in FIG. 1 can be used.

0052The inkjet recording device shown in FIG. 1 includes a housing provided with a paper ejection tray 118. In the housing, cassettes 100 and 101, paper feeding rollers 102 and 103, transfer rollers 104 and 105, resist rollers pair 106, transfer belt 107, fan 110, negative pressure chamber 111, transfer rollers 112, 113 and 114, Inkjet heads 115C, 115M, 115Y and 115Bk, ink cartridges 116C, 116M, 116Y and 116Bk, and tubes 117C, 117M, 117Y and 117Bk are installed.

0053The cassettes 100 and 101 contain recording media P having different sizes. The paper feeding roller 102 or 103 takes out the recording medium P corresponding to the size of the selected recording medium from the cassette 100 or 101 and conveys it to the transfer rollers 104 and 105 and the resist roller pair 106.

0054The transport belt 107 is tensioned by the drive roller 108 and the two driven rollers 109. Holes are provided on the surface of the transport belt 107 at predetermined intervals. A negative pressure chamber 111 connected to the fan 110 is installed inside the transport belt 107 in order to attract the recording medium P to the transport belt 107. Transport roller pairs 112, 113, and 114 are installed downstream of the transport belt 107 in the transport direction. A heater for heating the print layer formed on the recording medium P can be installed in the transport path from the transport belt 107 to the output tray 118.

0055Above the transport belt 107, four rows of inkjet heads that eject ink to the recording medium P according to the image data are arranged. Inkjet head 115C that ejects cyan (C) ink, inkjet head 115M that ejects magenta (M) ink, inkjet head 115Y that ejects yellow (Y) ink, and inkjet head that ejects black (Bk) ink from the upstream. The order is 115Bk.

0056Inkjet heads 115C, 115M, 115Y and 115Bk contain the corresponding inks Cyan (C) Ink Cartridge 116C, Magenta (M) Ink Cartridge 116M, Yellow (Y) Ink Cartridge 116Y, and Black (Bk) Ink. A cartridge 116Bk is provided. These cartridges 116C, 116M, 116Y and 116Bk are connected to the inkjet heads 115C, 115M, 115Y and 115Bk by tubes 117C, 117M, 117Y and 117Bk, respectively.

0057The ink composition contained in at least one of the ink cartridges 116C, 116M, 116Y and 116Bk is the ink composition according to the embodiment. Here, as an example, it is assumed that the ink compositions contained in the ink cartridges 116C, 116M, 116Y and 116Bk are all the ink compositions according to the embodiment.

0058Next, the image forming operation of this inkjet recording device will be described. First, an image processing means (not shown) starts image processing for recording, generates an image signal corresponding to the image data, and generates a control signal for controlling the operation of various rollers and the negative pressure chamber 111. To do.

0059The paper feeding roller 102 or 103 takes out the recording media P of the selected size one by one from the cassette 100 or 101 under the control of the image processing means, and conveys them to the conveying rollers 104 and 105 and the resist rollers 106. To do. The resist roller pair 106 corrects the skew of the recording medium P and conveys the recording medium P at a predetermined timing.

0060The negative pressure chamber 111 sucks air through the hole of the transport belt 107. Therefore, the recording medium P is sequentially conveyed to the positions below the inkjet heads 115C, 115M, 115Y, and 115Bk as the transfer belt 107 moves while being attracted to the transfer belt 107.

0061The inkjet heads 115C, 115M, 115Y and 115Bk eject ink in synchronization with the timing at which the recording medium P is conveyed under the control of the image processing means. As a result, a color image is formed at a desired position on the recording medium P.

0062After that, the transport roller pairs 112, 113, and 114 discharge the recording medium P on which the image is formed to the output tray 118. When the heater is installed in the transport path from the transport belt 107 to the output tray 118, the print layer formed on the recording medium P may be heated by the heater. Heating with a heater can enhance the adhesion of the print layer to the recording medium P, especially when the recording medium P is impermeable.

0063As described above, in this recording apparatus, the ink compositions contained in the ink cartridges 116C, 116M, 116Y and 116Bk are all the ink compositions according to the embodiment. Therefore, not only when the recording medium P is permeable like paper, but also when the recording medium P is impermeable, for example, the recording medium P has a smooth recording surface made of plastic, glass or metal. Even if it has, it is possible to form a print layer having excellent adhesion. Further, since the ink compositions contained in the ink cartridges 116C, 116M, 116Y and 116Bk are all the ink compositions according to the embodiment, in this recording device, the vicinity of the nozzles of the inkjet heads 115C, 115M, 115Y and 115Bk It is difficult for the ink composition to dry out. Therefore, this recording device has a low maintenance burden.

<p num="0064"> Specific examples will be described below. &lt;Preparation of pigment dispersion liquid&gt; 25 parts by mass of pigment, 5 parts by mass of surfactant and 70 parts by mass of pure water were mixed, and this mixed solution was subjected to a dispersion treatment by a bead mill. Here, Pigment Yellow 155 was used as the pigment, and polyoxyethylene alkyl ether was used as the surfactant. Zirconia beads were used as the pulverizing medium of the bead mill.</p><p num="0065"> The beads were then removed from the dispersion and the dispersion was centrifuged and filtered. A 1 μm membrane filter was used for filtration. As described above, a yellow pigment dispersion liquid containing a pigment in a proportion of 25% by mass was obtained.</p><p num="0066"> &lt;Preparation of ink composition&gt; The pigment dispersion and other components were mixed according to the formulations shown in Tables 1 to 3 below. In Tables 1 to 3, the numerical values shown in the column on the right side of the column displaying the components represent the content (parts by mass) of the components.</p><p num="0067"> Here, Acryt (registered trademark) WEM-202UH manufactured by Taisei Fine Chemicals Co., Ltd., which is an aqueous resin emulsion, was used as the core-shell particle source. As the discharge stabilizer, Surfinol (registered trademark) 465 manufactured by Nisshin Kagaku Kogyo Co., Ltd. was used. As a preservative, Lonza's Proxel® xL-2 was used.</p><p num="0068"> The mixture was stirred with a stirrer for 1 hour and then filtered through a 1 μm membrane filter. As a result, an ink composition was obtained.</p><p num="0069"><tables num="1"><img id="000002" he="182" wi="158" file="JP6190839B2_D0001.tif" img-format="tif" img-content="drawing" /></tables></p><p num="0070"><tables num="2"><img id="000003" he="170" wi="158" file="JP6190839B2_D0001.tif" img-format="tif" img-content="drawing" /></tables></p><p num="0071"><tables num="3"><img id="000004" he="180" wi="158" file="JP6190839B2_D0001.tif" img-format="tif" img-content="drawing" /></tables></p><p num="0072"> &lt;Evaluation of maintainability&gt; Printing was performed by an inkjet recording device using each of the ink compositions shown in Tables 1 to 3. Here, an inkjet recording device manufactured by TOSHIBA TEC Corporation was used. After printing, the inkjet head was fixed at a position away from the home position and left for 24 hours under a temperature condition of 25 ° C. After that, printing was performed again, and the ejection stability of the inkjet head was examined. Then, the maintainability was evaluated by comparing the stability of discharge with the following criteria. The results are summarized in Tables 1 to 3.</p><p num="0073"> : Discharge was unstable immediately after being left unattended, but stable discharge was immediately possible without cleaning operation. : Discharge was unstable immediately after being left unattended, but stable discharge became possible by cleaning within 2 times. Δ: Discharge was unstable immediately after being left unattended, but stable discharge became possible after three or more cleaning operations. X: Discharge immediately after being left unattended was unstable, and stable discharge could not be achieved even after repeated cleaning operations.</p><p num="0074"> &lt;Evaluation of storage stability&gt; For each of the ink compositions shown in Tables 1 to 3, the viscosity and surface tension of the ink composition were measured.</p><p num="0075"> In addition, 100 cc of each of the ink compositions shown in Tables 1 to 3 was weighed and placed in a glass sample bottle. The bottle was sealed and stored for 60 days in a high temperature bath set at 50 ° C. Then, the viscosity and surface tension of the ink composition were measured, and the presence or absence of a precipitate was examined.</p><p num="0076"> Then, the storage stability was evaluated by comparing these results with the following criteria. The results are summarized in Tables 1 to 3.</p><p num="0077"> : There was almost no change in physical properties, and there was no precipitation of precipitates. Δ: No major change in physical properties or a large amount of precipitate was formed, but a slight change in physical properties was observed or a small amount of precipitate was formed. X: A large change in physical properties or a large amount of precipitate was generated.</p><p num="0078"> &lt;Evaluation of adhesion&gt; First, printing was performed by an inkjet recording device using each of the ink compositions shown in Tables 1 to 3.</p><p num="0079"> Here, a solid printing was performed on a square area having a side of 10 mm on a recording medium using an inkjet recording device manufactured by TOSHIBA TEC Corporation equipped with a piezo head. The printed layer thus formed was heated with a dryer for 10 seconds. At this time, the surface temperature of the recording medium was 50 ° C. or less.</p><p num="0080"> As the recording medium, a non-permeable recording medium made of the following materials was used. PVC polyethylene terephthalate stainless aluminum Glass</p><p num="0081"> Next, an adhesive tape was applied to the printing layer, and the adhesive tape was rubbed with a finger three times. As the adhesive tape, Scotch (registered trademark) mending tape 810 manufactured by Sumitomo Three F Co., Ltd. was used. Then, the adhesive tape was peeled off, and the state of the printed layer was visually observed. Then, the adhesion was evaluated by comparing this state with the following criteria.</p><p num="0082"> : No pigment was removed from the recording medium. Δ: A small amount of pigment fell off from the recording medium. X: A large amount of pigment was shed from the recording medium.</p><p num="0083"> The present invention is not limited to the above-described embodiment as it is, and at the implementation stage, the components can be modified and embodied within a range that does not deviate from the gist thereof. In addition, various inventions can be formed by an appropriate combination of the plurality of components disclosed in the above-described embodiment. For example, some components may be removed from all the components shown in the embodiments. Further, components over different embodiments may be combined as appropriate. <u style="single"> The inventions described in the original claims are added below.</u><u style="single">[1]</u><u style="single"> A dispersion medium containing water and glycol ether having a boiling point of 220 ° C or higher,</u><u style="single"> With pigments</u><u style="single"> An ink composition for inkjet recording containing core-shell particles including a core made of a hydrophobic acrylic resin and a shell made of at least one of a water-based urethane resin and an acrylic graft water-based urethane resin.</u><u style="single">[2]</u><u style="single"> The ink composition for inkjet recording according to [1], wherein the ratio of the core-shell particles to the ink composition is in the range of 1 to 30% by mass.</u><u style="single">[3]</u><u style="single"> The ink composition for inkjet recording according to [1] or [2], wherein the proportion of the glycol ether in the ink composition is in the range of 0.5 to 10% by mass.</u><u style="single">[4]</u><u style="single"> The ink composition for inkjet recording according to any one of [1] to [3], wherein the glycol ether is a tripropylene glycol monomethyl ether.</u><u style="single">[5]</u><u style="single"> The ink composition for inkjet recording according to any one of [1] to [4], wherein the dispersion medium further contains glycerin.</u></p>

0084100 ... Cassette, 101 ... Cassette, 102 ... Paper Roller, 103 ... Paper Roller, 104 ... Transport Roller Pair, 105 ... Transport Roller Pair, 106 ... Resist Roller Pair, 107 ... Transfer belt, 110 ... Fan, 111 ... Negative pressure chamber, 112 ... Transfer roller pair, 113 ... Transfer roller pair, 114 ... Transfer roller pair, 115Bk .. Inkjet Head, 115C ... Inkjet Head, 115M ... Inkjet Head, 115Y ... Inkjet Head, 116Bk ... Ink Cartridge, 116C ... Ink Cartridge, 116M ... Ink Cartridge, 116Y ... Ink cartridge, 117Bk ... tube, 117C ... tube, 117M ... tube, 117Y ... tube, 118 ... paper output tray, P ... recording medium.