Magenta ink composition, ink cartridge, and recording system and recorded matter using the same

Technical Field

0001The present invention relates to a new magenta ink composition, and more particularly, a magenta ink composition that, when recorded, is excellent in color development, graininess, and gloss, is less likely to cause clogging in an ink jet recording head, and is excellent in color reproduction in a high-chroma and high-lightness red region, an ink cartridge including the same, and a recording system and a recorded matter using the same.

Background Art

0002Conventionally, as a color ink jet recording magenta ink, a magenta ink using pigment such as single crystal C.I. pigment red 122 or C.I. pigment violet 19 or 32 as a coloring material was suggested (for example, see Patent Document 1 and Patent Document 2).

0003The single crystal C.I. pigment red 122 (hereinafter, also referred to single crystal PR122) is relatively excellent in color development, graininess, and gloss. In addition, since color development is good, color reproduction is relatively good although the concentration of the pigment is relatively low. However, there is a need for a magenta ink that, when recorded, is excellent in color development, graininess, and gloss and is excellent in color reproduction in a high-chroma and high-lightness red region and violet region.

0004Even in the C.I. pigment violet 19 or 32 (hereinafter, also referred to as PV19 or PV32), a new improvement of color development, graininess, and gloss when recorded and color reproduction in a high-chroma and high-lightness red region and violet region is required. That is, the PV19 has a high L* value, but has a relatively small a* value. Accordingly, new high chroma is required. Since the PV19 has a relatively high b* value, there is a need for a magenta ink which is excellent in color reproduction in a low-lightness violet region. Meanwhile, since a high a* value and a high L* value are not sufficiently realized in the PV32, new high-lightness is required. In addition, a new improvement of color development, graininess and gloss is required.

0005<ul id="ul0001" list-style="none" compact="compact"><li>Patent Document 1: Japanese Unexamined Patent Application NO. <patcit id="pcit0001" dnum="JP2003268275A"><text>2003-268275</text></patcit></li><li>Patent Document 2: Japanese Unexamined Patent Application NO. <patcit id="pcit0002" dnum="JP2002030230A"><text>2002-030230</text></patcit></li></ul>

Disclosure of the Invention

Problems to be Solved by the Invention

0006An object of the present invention is to provide a magenta ink composition that, when recorded, is excellent in color development, graininess, and gloss, is less likely to cause clogging in an ink jet recording head, and is excellent in color reproduction in a high-chroma and high-lightness red region and violet region.

0007Another object of the present invention is to provide an ink cartridge including the excellent magenta ink composition.

0008Another object of the present invention is to provide a recording system and a recorded matter using the excellent magenta ink composition.

Means for Solving the Problems

0009As a result of intensive investigation, the present inventors found that the magenta ink composition as defined in claim 1 which has an L* value of not less than 60 and a b* value of not more than -17 when the a* value in CIE standard calculated from a visible absorption spectrum in a not more than 10000-fold diluted aqueous solution is 80 is excellent in color development, graininess, and gloss and is excellent in color reproduction in a high-chroma and high-lightness red region as a coloring material, and completed the present invention.

0010That is, according to the present invention, there are (1) a magenta ink composition wherein an L* value is not less than 60 and a b* value is not more than -17 when an a* value in CIE standard calculated from a visible absorption spectrum in a not more than 10000-fold diluted aqueous solution is 80 including at least a solid solution of γ-type C.I. pigment violet 19 and C.I. pigment red 202 and wherein in the solid solution, the weight of the γ-type C.I. pigment violet 19 is larger than that of the C.I. pigment red 202; (2) the magenta ink composition according to (1), wherein the L* value is not less than 96 and the a* value is not less than 7.5 in the CIE standard calculated from the visible absorption spectrum in an aqueous solution having a pigment concentration of 2×10^-3 g/l; (3) the magenta ink composition according to (1), wherein the a* value is not less than 11.5 and the b* value is not more than -5.5 when the L* value in CIE standard calculated from the visible absorption spectrum in a not more than 10000-fold diluted aqueous solution is 94; (5) the magenta ink composition according to (1) including a pigment dispersion obtained by a method of kneading the solid solution at a temperature higher than 120 °C and preparing a pigment kneaded material; (6) the magenta ink composition according to (5) including a pigment dispersion obtained by a method including kneading the solid solution at a temperature higher than 120 °C and preparing a pigment kneaded material and dispersing the composition including the pigment kneaded material to a dispersion treatment material; (7) the magenta ink composition according to (6), wherein the method includes performing an ultrafiltration classification process with respect to the dispersion treatment material; (9) the magenta ink composition according to (1), wherein, in the solid solution, a ratio of the weight of the γ-type C.I. pigment violet 19 to the weight of the C.I. pigment red 202 is preferably 70/30 to 50/50; (10) the magenta ink composition according to any one of (1) to (9) including one, two, or more types of polyhydric alcohols, sugars and polyhydric alcohols with ethylene oxide chains as a wetting agent; (11) the magenta ink composition according to any one of (1) to (9) including one, two, or more types of pyrrolidones, alkanediols, glycol eters as a penetrant; (12) the magenta ink composition according to any one of claims (1) to (9) including one, two, or more types of acetylene glycols and polysiloxanes as the surfactant; and (13) the magenta ink composition according to (12), wherein polysiloxanes are expressed by the following formula; <chemistry id="chem0001" num="0001"><img file="EP1967558B2_D0001.tif" /></chemistry> (In Formula, R denotes a hydrogen atom or a methyl group, a denotes an integer of 7 to 13, m denotes an integer of 2 to 770 and n denotes an integer of 1 to 5). (14) the magenta ink composition according to (12), wherein polysiloxanes are expressed by the following formula; <chemistry id="chem0002" num="0002"><img file="EP1967558B2_D0002.tif" /></chemistry> (In Formula, R denotes a hydrogen atom or a methyl group, a denotes an integer of 2 to 11, m denotes an integer of 2 to 50 and n denotes an integer of 1 to 5.); (15) the magenta ink composition for ink jet recording according to any one of (1) to (9) which is used for ink jet recording; (16) an ink cartridge including the magenta ink composition according to any one of (1) to (9); (17) a recording system for forming an image using the magenta ink composition according to any one of (1) to (9); and (18) a recorded matter on which an image is formed using the magenta ink composition according to any one of (1) to (9).

Effect of the Invention

0011According to the present invention, there are provided a magenta ink composition that, when recorded, is excellent in color development, graininess, and gloss, is less likely to cause clogging in an ink jet recording head, and is excellent in color reproduction in a high-chroma and high-lightness red region and violet region, an ink cartridge including the excellent ink composition, and a recording system and a recorded matter using the excellent ink composition.

Brief Description of the Drawings

0012<ul id="ul0002" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1</figref> is a graph showing a relationship between a* values and b* values of recorded matters recorded using magenta ink compositions.</li><li><figref idref="f0002">Fig. 2</figref> is a graph showing a relationship between a* values and L* values of recorded matters recorded using magenta ink compositions.</li><li><figref idref="f0003">Fig. 3</figref> is a graph showing a relationship between L* values and a* values of aqueous solutions diluted using magenta ink compositions.</li><li><figref idref="f0004">Fig. 4</figref> is a graph showing a relationship between L* values and b* values of aqueous solutions diluted using magenta ink compositions.</li></ul>

Best Mode for Carrying out the Invention

0013Hereinafter, embodiments of the present invention will be described. The following embodiments are only examples of the present invention and the present invention is not limited to the following embodiments. The present invention may be modified without departing from the scope of the present invention.

[Magenta Ink Composition]

0014A magenta ink composition according to the present invention is defined in claim 1. By this configuration, a magenta ink composition that, when recorded, is excellent in color development, graininess, and gloss, is less likely to cause clogging in an ink jet recording head, and is excellent in color reproduction in a high-chroma and high-lightness red region and violet region is provided.

0015In the magenta ink composition according to the present invention, since color development is good, color reproduction in the high-chroma and high-lightness region is excellent although a pigment concentration is relatively low. Since color reproduction is excellent although the pigment concentration is relatively low, it is possible to prevent the viscosity of the ink from being by increasing the pigment concentration. In the magenta ink composition according to the present invention, color development is remarkably improved in regular paper when the concentration of the pigment is increased. The magenta ink composition according to the present invention is excellent in gas resistance, light resistance and metamerism resistance.

0016The magenta ink composition preferably has an L* value of not less than 96 in CIE standard calculated from the visible absorption spectrum and an a* value of not less than 7.5 in an aqueous solution having a pigment concentration of 2×10^-3g/l. By this suitable configuration, in addition to the effect of the present invention, a magenta ink composition which is remarkably excellent in graininess and color development is provided.

0017The magenta ink composition preferably has an a* value of not less than 11.5 and a b* value of not more than -5.5 when the L* value in CIE standard calculated from the visible absorption spectrum in a not more than 10000-fold diluted aqueous solution is 94. By this suitable configuration, in addition to the effect of the present invention, a magenta ink composition which is remarkably excellent in graininess, color development, gloss, metamerism resistance, gas resistance, and light resistance is provided.

0018The suitable magenta ink composition includes at least a solid solution of γ-type C.I. pigment violet 19 and C.I. pigment red 202. By this configuration, the effect of the present invention will be realized. The γ-type C.I. pigment violet 19 and C.I. pigment red 202 indicates crystal in which γ-type PV19 and PR202 are dissolved in each other in a solid state.

0019The suitable magenta ink composition includes at least a predetermined solid solution and may further include other magenta-based pigments such as PV19 or PV32 or other pigments if the solid solution is included. A ratio of γ-type PV19 to PR202 of the solid solution in amount can be properly adjusted in the scope of the present invention.

0020The L* value, the a* value and the b* value in CIE standard calculated from the visible absorption spectrum can be obtained by measuring transmissivity under the condition that a scan speed is 600 nm/min, a measurement wavelength range is 380 to 800 nm and a slit width is 2.0 nm using U3300 manufactured by Hitachi Ltd. and performing calculation in a D65 light source and a viewing angle of 2 degrees.

0021The magenta ink composition preferably includes a pigment dispersion obtained by a method of kneading the solid solution at a temperature higher than 120 °C and preparing a pigment kneaded material.

0022The magenta ink composition preferably includes a pigment dispersion obtained by a method including kneading the solid solution at a temperature higher than 120 °C and preparing a pigment kneaded material and dispersing the composition including the pigment kneaded material to a dispersion treatment material.

0023The method preferably includes a step of performing an ultrafiltration classification process with respect to the dispersion treatment material. The solid solution has a fast dispersion speed and excellent production efficiency. However, if the dispersion is rapidly made, clogging or unevenness in color development occurs. Accordingly, in order to efficiently suppress clogging, kneading is mad before the dispersion of fine particles. In order to efficiently suppress color unevenness, the ultrafiltration classification is performed.

0024In the solid solution, the weight of the γ-type C.I. pigment violet 19 is larger than that of the C.I. pigment red 202. In the solid solution, a ratio of the weight of the γ-type C.I. pigment violet 19 to the weight of the C.I. pigment red 202 is preferably 70/30 to 50/50. By this suitable configuration, a magenta ink composition that, when recorded, is excellent in color development and is excellent in color reproduction in a high-chroma and high-lightness red region and violet region is provided.

0025It is preferable that the magenta ink composition according to the present invention uses the pigment as the coloring material and includes a dispersing agent for dispersing the pigment. Dispersing agents which can be used in this type of pigment ink can be used without limitation and, for example, a cation dispersing agent, an anion dispersing agent, a nonionic dispersing agent, or a surfactant may be used. Examples of the anion dispersing agent include polyacrylic acid, polymethacrylic acid, acrylic acid-acrylonitrile copolymers, vinyl acetate-acrylic ester copolymers, acrylic acid-acrylate alkyl ester copolymers, styrene-acrylic acid copolymers, styrene-methacrylic acid copolymers, styrene-acrylic acid-acrylate alkyl ester copolymers, styrene-methacrylic acid-acrylate alkyl ester copolymers, styrene-α-methylstyrene-acrylic acid copolymers, styrene-α-methylstyrene-acrylic acid-acrylate alkyl ester copolymers, styrene-maleic acid copolymers, vinylnaphthalene-maleic acid copolymers, vinyl acetate-ethylene copolymers, vinyl acetate-fatty acid vinyl ethylene copolymers, vinyl acetate-maleate copolymers, vinyl acetate-crotonic acid copolymers, and vinyl acetate/acrylic acid copolymers. Examples of the non-ionic dispersing agent include polyvinyl pyrrolidone, polypropylene glycol, and vinyl pyrrolidone-vinyl acetate copolymers. Examples of the surfactants as the dispersing agent include the anion surfactant such as sodium dodecylbenzenesulfonate and sodium laurylate, ammonium salts of polyoxyethylene alkyl ether sulfates, and the nonionic surfactant such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, polyoxyethylene sorbitan fatty acid esters, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkylamines, and polyoxyethylene alkylamides. In particular, from the viewpoint of increasing the dispersion stability of the pigment, the use of styrene-(meth)acrylic acid copolymers is preferred.

0026In the magenta ink according to the present invention, one, two, or more types of polyhydric alcohols, sugars and polyhydric alcohols with ethylene oxide chains is preferably included as a wetting agent. By adding the wetting agent, it is possible to prevent the ink from being dried and prevent a head of an ink jet printer from being clogged. Examples of the wetting agent include ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, polypropylene glycol, propylene glycol, butylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, glycerin, trimethylolethane, trimethylolpropane, and other polyhydric alcohols; sugar alcohol and other sugars; and ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monobutyl ether, and other polyhydric alcohols with ethylene oxide chains. One, two, or more types of these may be used.

0027In the magenta ink composition according to the present invention, one, two, or more types of pyrrolidones, alkanediols, glycol eters is preferably included as a penetrant. By adding the penetrant, the wettability of the recording medium can be increased and the permeability of the ink can be increased. Examples of the penetrant include 2-pyrrolidone, N-methyl-2-pyrrolidone and other pyrrolidones; 1,2-pentanediol, 1,2-hexanediol, and other alkanediols; and ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, propylene glycol monobutyl eter, dipropylene glycol monobutyl eter and other glycol eters. One, two, or more types of these may be used.

0028In the magenta ink composition according to the present invention, one, two, or more types of acetylene glycols and polysiloxanes is preferably included as the surfactant. By adding the surfactant, the wettability of the recording medium can be increased and the permeability of the ink can be increased.

0029As polysiloxanes which can be used as the surfactant, polyorganosiloxanes expressed by the following formula are preferred. <chemistry id="chem0003" num="0003"><img file="EP1967558B2_D0003.tif" /></chemistry> (In Formula, R denotes a hydrogen atom or a methyl group, a denotes an integer of 7 to 13, m denotes an integer of 2 to 770 and n denotes an integer of 1 to 5.) By this suitable configuration, a recorded matter which is more excellent in gloss can be obtained.

0030As polysiloxanes, polyorganosiloxanes expressed by the following formula are also preferred. <chemistry id="chem0004" num="0004"><img file="EP1967558B2_D0004.tif" /></chemistry> (In Formula, R denotes a hydrogen atom or a methyl group, a denotes an integer of 2 to 11, m denotes an integer of 2 to 50 and n denotes an integer of 1 to 5.) By this suitable configuration, it is possible to suppress agglomeration unevenness when recorded on print paper.

0031If the magenta ink composition according to the present invention includes polyorganosiloxane, one, two, or more types of polyorganosiloxane may be included.

0032In the magenta ink composition according to the present invention, from the viewpoint of reducing the ink drying time, a low-boiling organic solvent may be included. Examples of low-boiling solvents include methanol, ethanol, n-propyl alcohol, iso-propyl alcohol, n-butanol, sec-butanol, tert-butanol, isobutanol, n-pentanol, and the like; and one, two, or more types of these may be used. The use of a monohydric alcohol in particular is preferred.

0033In the magenta ink composition according to the present invention, components such as the pigment, the dispersing agent, the wetting agent, the low-boiling organic solvent, the penetrant, and the surfactant are included and water is included as the balance. Deionized water, ultrafiltrated water, reverse osmotic water, distilled water, or another type of pure or ultrapure water is preferably used for water. In particular, water obtained by sterilizing this type of water through irradiation with ultraviolet light, addition of hydrogen peroxide, or the like is preferred because the occurrence of mold and bacteria are prevented over a long period of time.

0034The magenta ink composition according to the present invention may contain, as required, water-soluble rosins or other stabilizers, sodium benzoate or other antifungal agents/preservatives, allophanates or other antioxidants/ultraviolet absorbers, chelating agents, pH regulators, and other additives; and one, two, or more types of these may be used.

0035The magenta ink composition according to the present invention is preferably used in inkjet recording processes, which are recording medium methods whereby droplets of ink are ejected from a nozzle, and the droplets are allowed to adhere to a recording medium to form characters and/or images, and are particularly preferred for use in on-demand inkjet recording processes. Examples of on-demand inkjet recording processes include piezoelement recording methods whereby recording is performed by using a piezoelement disposed in the printer head, and thermal jet recording methods whereby recording is performed by using thermal energy generated by a heater or other component of a heating resistive element disposed in the printer head, and may be advantageously used in either type of inkjet recording method.

0036The magenta ink composition according to the present invention may be an ink jet recording magenta ink composition which is used for ink jet recording.

[Ink Cartridge]

0037An ink cartridge according to the present invention includes the above-described magenta ink composition. In the ink cartridge according to the present invention, it is possible to obtain an image that, when recorded, is excellent in color development, graininess, and gloss, is less likely to cause clogging in an ink jet recording head, and is excellent in color reproduction in a high-chroma and high-lightness red region.

[Recording System]

0038A recording system according to the present invention forms an image using the above-described magenta ink composition. In the ink cartridge according to the present invention, it is possible to obtain an image that, when recorded, is excellent in color development, graininess, and gloss, is less likely to cause clogging in an ink jet recording head, and is excellent in color reproduction in a high-chroma and high-lightness red region.

[Recorded Matter]

0039In a recorded matter according to the present invention, an image is formed using the above-described magenta ink composition.

0040The magenta ink composition according to the present invention is applicable to a recording medium which is generally used in an ink jet recording method as a recording medium for forming an image without limitation and is suitably applied to a regular paper (a recording medium in which a fiber is exposed to a recorded surface) and media having a coating layer.

Embodiments

0041The present invention is described in detail below with embodiments and experimental examples of the present invention, but the present invention is not limited in any way by these embodiments. It may be apparent by those skilled in the art that the following embodiments may be variously modified and the modifications are included in the scope of the claims.

[Example A]

0042As the magenta ink composition according to the present invention, a magenta ink composition which is a solid solution of γ-type PV19 and PR202 (hereinafter, referred to as a solid solution) and includes a solid solution type 1 in which a ratio of the weight of γ-type PV19 to the weight of PR202 is 70:30 was prepared. A composition (M1-1) in which the concentration of the solid solution type 1 is 2 wt%, a composition (M1-2) in which the concentration of the solid solution type 1 is 4 wt%, and a composition (M1-3) in which the concentration of the solid solution type 1 is 6 wt% were prepared.

<M1-1; Embodiment>

0043<tables id="tabl0001" num="0001"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="83mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><tbody><row><entry>Solid solution type 1</entry><entry align="right">2.0 wt %</entry></row><row><entry>Dispersing agent (styrene-acrylic acid copolymer)</entry><entry align="right">2.8 wt %</entry></row><row><entry>Glycerin</entry><entry align="right">12.0 wt %</entry></row><row><entry>1,2-hexanediol</entry><entry align="right">7.0 wt %</entry></row><row><entry>Triethanolamine</entry><entry align="right">0.9 wt %</entry></row><row><entry>KF-353A (manufactured by Shin-Etsu Chemical Co., Ltd.)</entry><entry align="right">0.1 wt%</entry></row><row><entry>Ultrapure water</entry><entry align="right">Remainder</entry></row><row><entry align="center">Total</entry><entry align="right">100.0 wt %</entry></row></tbody></tgroup></table></tables>

<M1-2; Embodiment>

0044<tables id="tabl0002" num="0002"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="73mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><tbody><row><entry>Solid solution type 1</entry><entry align="right">4.0 wt %</entry></row><row><entry>Dispersing agent (styrene-acrylic acid copolymer)</entry><entry align="right">2.0 wt %</entry></row><row><entry>Glycerin</entry><entry align="right">14.0 wt %</entry></row><row><entry>1,2-hexanediol</entry><entry align="right">7.0 wt %</entry></row><row><entry>Triethanolamine</entry><entry align="right">0.9 wt %</entry></row><row><entry>KF-353A (made by Shin-Etsu Chemical Co., Ltd.)</entry><entry align="right">0.1 wt%</entry></row><row><entry>Ultrapure water</entry><entry align="right">Remainder</entry></row><row><entry align="center">Total</entry><entry align="right">100.0 wt %</entry></row></tbody></tgroup></table></tables>

<M1-3; Embodiment>

0045<tables id="tabl0003" num="0003"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="73mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><tbody><row><entry>Solid solution type 1</entry><entry align="right">6.0 wt %</entry></row><row><entry>Dispersing agent (styrene-acrylic acid copolymer)</entry><entry align="right">2.4 wt %</entry></row><row><entry>Glycerin</entry><entry align="right">12.0 wt %</entry></row><row><entry>1,2-hexanediol</entry><entry align="right">7.0 wt %</entry></row><row><entry>Triethanolamine</entry><entry align="right">0.9 wt %</entry></row><row><entry>KF-353A (made by Shin-Etsu Chemical Co., Ltd.)</entry><entry align="right">0.1 wt %</entry></row><row><entry>Ultrapure water</entry><entry align="right">Remainder</entry></row><row><entry align="center">Total</entry><entry align="right">100.0 wt %</entry></row></tbody></tgroup></table></tables>

0046Similarly, as the embodiment, a magenta ink composition having the same composition as (M1-1) to (M1-3) except that a solid solution type 2 in which a ratio of the weight of γ-type PV19 to the weight of PR202 is 55:45 is used instead of the solid solution type 1 was prepared. A composition (M2-1) in which the concentration of the solid solution type 2 is 2 wt%, a composition (M2-2) in which the concentration of the solid solution type 2 is 4 wt%, and a composition (M2-3) in which the concentration of the solid solution type 2 is 6 wt% were prepared.

0047As a comparative example, a magenta ink composition having the same composition as (M1-1) to (M1-3) except that single crystal PR122 is included instead of the solid solution type 1 was prepared. A composition (m3-1) in which the concentration of the single crystal PR122 is 2 wt%, a composition (m3-2) in which the concentration of single crystal PR122 is 4 wt%, and a composition (m3-3) in which the concentration of single crystal PR122 is 6 wt% were prepared.

0048As another comparative example, a magenta ink composition having the same composition as (M1-1) to (M1-3) except that PV19 is included instead of the solid solution type 1 was prepared. A composition (m4-1) in which the concentration of the PV19 is 2 wt%, a composition (m4-2) in which the concentration of PV19 is 4 wt%, and a composition (m4-3) in which the concentration of PV19 is 6 wt% were prepared.

0049As another comparative example, a magenta ink composition having the same composition as (M1-1) to (M1-3) except that PV32 is included instead of the solid solution type 1 was prepared. A composition (m5-1) in which the concentration of the PV32 is 2 wt%, a composition (m5-2) in which the concentration of PV32 is 4 wt%, and a composition (m5-3) in which the concentration of PV32 is 6 wt% were prepared.

0050With respect to the prepared magenta ink compositions, 2000-fold dilution and 10000-fold dilution were performed by water and the L* value, the a* value and the b* value were measured with respect to the diluted aqueous solutions. The L* value, the a* value and the b* value of the aqueous solutions were measured U3300 manufactured by Hitachi Ltd. In more detail, the transmissivity was measured under the condition that a scan speed is 600 nm/min, a measurement wavelength range is 380 to 800 nm and a slit width is 2.0 nm and a calculation was performed in a D65 light source and a viewing angle of 2 degrees. The result is shown in Table 1.

0051<tables id="tabl0004" num="0004"><table frame="all"><title>[Table 1]</title><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="27mm" /><colspec colnum="2" colname="col2" colwidth="14mm" /><colspec colnum="3" colname="col3" colwidth="14mm" /><colspec colnum="4" colname="col4" colwidth="15mm" /><colspec colnum="5" colname="col5" colwidth="14mm" /><colspec colnum="6" colname="col6" colwidth="14mm" /><colspec colnum="7" colname="col7" colwidth="15mm" /><thead><row><entry morerows="1" align="center" valign="middle">Dilution degree</entry><entry namest="col2" nameend="col4" align="center" valign="middle">2000-fold</entry><entry namest="col5" nameend="col7" align="center" valign="middle">10000-fold</entry></row><row><entry align="center" valign="middle">L*</entry><entry align="center" valign="middle">a*</entry><entry align="center" valign="middle">b*</entry><entry align="center" valign="middle">L*</entry><entry align="center" valign="middle">a*</entry><entry align="center" valign="middle">b*</entry></row></thead><tbody><row><entry align="center" valign="middle">M1-1 (2%)</entry><entry align="center" valign="middle">87.54</entry><entry align="center" valign="middle">28.20</entry><entry align="center" valign="middle">-12.76</entry><entry align="center" valign="middle">96.46</entry><entry align="center" valign="middle">8.23</entry><entry align="center" valign="middle">-3.85</entry></row><row><entry align="center" valign="middle">M1-2 (4%)</entry><entry align="center" valign="middle">78.18</entry><entry align="center" valign="middle">51.71</entry><entry align="center" valign="middle">-21.32</entry><entry align="center" valign="middle">94.28</entry><entry align="center" valign="middle">13.43</entry><entry align="center" valign="middle">-6.18</entry></row><row><entry align="center" valign="middle">M1-3 (6%)</entry><entry align="center" valign="middle">72.69</entry><entry align="center" valign="middle">64.22</entry><entry align="center" valign="middle">-24.91</entry><entry align="center" valign="middle">91.39</entry><entry align="center" valign="middle">20.35</entry><entry align="center" valign="middle">-9.23</entry></row><row><entry align="center" valign="middle">M2-1 (2%)</entry><entry align="center" valign="middle">89.13</entry><entry align="center" valign="middle">22.00</entry><entry align="center" valign="middle">-12.35</entry><entry align="center" valign="middle">96.28</entry><entry align="center" valign="middle">7.54</entry><entry align="center" valign="middle">-4.31</entry></row><row><entry align="center" valign="middle">M2-2 (4%)</entry><entry align="center" valign="middle">80.91</entry><entry align="center" valign="middle">38.76</entry><entry align="center" valign="middle">-20.68</entry><entry align="center" valign="middle">94.55</entry><entry align="center" valign="middle">11.17</entry><entry align="center" valign="middle">-6.40</entry></row><row><entry align="center" valign="middle">M2-3 (6%)</entry><entry align="center" valign="middle">74.35</entry><entry align="center" valign="middle">52.63</entry><entry align="center" valign="middle">-26.86</entry><entry align="center" valign="middle">93.19</entry><entry align="center" valign="middle">13.90</entry><entry align="center" valign="middle">-7.82</entry></row><row><entry align="center" valign="middle">m3-1 (2%)</entry><entry align="center" valign="middle">86.31</entry><entry align="center" valign="middle">25.29</entry><entry align="center" valign="middle">-14.27</entry><entry align="center" valign="middle">95.81</entry><entry align="center" valign="middle">7.12</entry><entry align="center" valign="middle">-4.30</entry></row><row><entry align="center" valign="middle">m3-2 (4%)</entry><entry align="center" valign="middle">76.59</entry><entry align="center" valign="middle">44.45</entry><entry align="center" valign="middle">-22.90</entry><entry align="center" valign="middle">93.98</entry><entry align="center" valign="middle">10.69</entry><entry align="center" valign="middle">-6.41</entry></row><row><entry align="center" valign="middle">m3-3 (6%)</entry><entry align="center" valign="middle">69.53</entry><entry align="center" valign="middle">58.43</entry><entry align="center" valign="middle">-27.71</entry><entry align="center" valign="middle">91.47</entry><entry align="center" valign="middle">14.77</entry><entry align="center" valign="middle">-8.71</entry></row><row><entry align="center" valign="middle">m4-1 (2%)</entry><entry align="center" valign="middle">88.32</entry><entry align="center" valign="middle">23.82</entry><entry align="center" valign="middle">-7.98</entry><entry align="center" valign="middle">97.50</entry><entry align="center" valign="middle">5.28</entry><entry align="center" valign="middle">-1.86</entry></row><row><entry align="center" valign="middle">m4-2 (4%)</entry><entry align="center" valign="middle">80.21</entry><entry align="center" valign="middle">43.10</entry><entry align="center" valign="middle">-14.49</entry><entry align="center" valign="middle">95.24</entry><entry align="center" valign="middle">10.33</entry><entry align="center" valign="middle">-3.98</entry></row><row><entry align="center" valign="middle">m4-3 (6%)</entry><entry align="center" valign="middle">73.96</entry><entry align="center" valign="middle">54.34</entry><entry align="center" valign="middle">-16.54</entry><entry align="center" valign="middle">93.24</entry><entry align="center" valign="middle">14.33</entry><entry align="center" valign="middle">-5.36</entry></row><row><entry align="center" valign="middle">m5-1 (2%)</entry><entry align="center" valign="middle">74.45</entry><entry align="center" valign="middle">40.90</entry><entry align="center" valign="middle">-24.57</entry><entry align="center" valign="middle">93.98</entry><entry align="center" valign="middle">9.27</entry><entry align="center" valign="middle">-6.16</entry></row><row><entry align="center" valign="middle">m5-2 (4%)</entry><entry align="center" valign="middle">58.47</entry><entry align="center" valign="middle">67.25</entry><entry align="center" valign="middle">-35.56</entry><entry align="center" valign="middle">88.46</entry><entry align="center" valign="middle">17.87</entry><entry align="center" valign="middle">-11.65</entry></row><row><entry align="center" valign="middle">m5-3 (6%)</entry><entry align="center" valign="middle">50.47</entry><entry align="center" valign="middle">81.65</entry><entry align="center" valign="middle">-35.00</entry><entry align="center" valign="middle">80.14</entry><entry align="center" valign="middle">25.95</entry><entry align="center" valign="middle">-15.01</entry></row></tbody></tgroup></table></tables>

0052As shown in Table 1, it can be seen that, in the magenta ink compositions M1 and M2 according to the embodiments of the present invention, the L* value and the a* value in the CIE standard calculated from the visible absorption spectrum in a not more than 10000-fold diluted aqueous solution are high and color reproduction is excellent. In addition, it can be seen that, in the magenta ink compositions M1 and M2 according to the embodiments of the present invention, the CIE standard calculated from the visible absorption spectrum in a not more than 10000-fold diluted aqueous solution has slightly lower lightness than PV19 (m4), but the b* value is smaller.

0053As shown in Table 1, in the magenta ink compositions M1 and M2 according to the embodiments, the L* value is not less than 96 and the a* value is not less than 7.5 in 10000-fold dilution and 2 wt% (aqueous solution having a pigment concentration of 2×10^-3g/l).

0054Graphs showing the 10000-fold diluted aqueous solution and data of the concentration of 2.0 wt% shown in <figref idref="f0003">Figs. 3</figref> and <figref idref="f0004">4</figref>. That is, <figref idref="f0003">Fig. 3</figref> is a graph showing a relationship between the L* value and the a* value in the 10000-fold diluted aqueous solution and <figref idref="f0004">Fig. 4</figref> is a graph showing a relationship between the L* value and the b* value in the 10000-fold diluted aqueous solution.

0055As shown in <figref idref="f0003">Figs. 3</figref> and <figref idref="f0004">4</figref>, the magenta ink compositions M1 and M2 according to the embodiments, when the L* value in a not more than 10000-fold diluted aqueous solution is 94, the a* value was not less than 11.5 and the b* value was not more than -5.5.

[Embodiment B]

0056The magenta ink composition including the solid solution type 1 was prepared by the following composition. <tables id="tabl0005" num="0005"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="73mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><tbody><row><entry>Solid solution type 1</entry><entry align="right">4.0 wt %</entry></row><row><entry>Dispersing agent (styrene-acrylic acid copolymer)</entry><entry align="right">2.0 wt %</entry></row><row><entry>Glycerin</entry><entry align="right">14.0 wt %</entry></row><row><entry>1,2-hexanediol</entry><entry align="right">7.0 wt %</entry></row><row><entry>Triethanolamine</entry><entry align="right">0.9 wt %</entry></row><row><entry>KF-353A (made by Shin-Etsu Chemical Co., Ltd.)</entry><entry align="right">0.1 wt%</entry></row><row><entry>Ultrapure water</entry><entry align="right">Remainder</entry></row><row><entry align="center">Total</entry><entry align="right">100.0 wt %</entry></row></tbody></tgroup></table></tables>

0057Instead of the solid solution type 1 of 4.0 wt%, an ink composition having the same composition except that the solid solution type 2 of the solid solution of 4.0 wt% is used, an ink composition having the same composition except that single crystal PR122 of 4.0 wt% is used, an ink composition having the same composition except that PV19 of 4.0 wt% is used, and an ink composition having the same composition except that PV32 of 4.0 wt% is used were prepared.

0058Thereafter, the prepared magenta ink compositions are diluted by water such that the a* value becomes 80. The aqueous solution including the solid solution type 1 requires about 810-fold dilution, the aqueous solution including the solid solution type 2 requires about 650-fold dilution, the aqueous solution including single crystal PR122 requires about 700-fold dilution, the aqueous solution including PV19 requires about 500-fold dilution, and the aqueous solution including the solid solution type 1 including PV32 requires about 1500-fold dilution.

0059The L* value, the a* value and the b* value of the aqueous solutions were measured U3300 manufactured by Hitachi Ltd. In more detail, the transmissivity was measured under the condition that a scan speed is 600 nm/min, a measurement wavelength range is 380 to 800 nm and a slit width is 2.0 nm and a calculation was performed in a D65 light source and a viewing angle of 2 degrees.

0060The result is shown in Table 2. <tables id="tabl0006" num="0006"><table frame="all"><title>[Table 2]</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="41mm" /><colspec colnum="2" colname="col2" colwidth="14mm" /><colspec colnum="3" colname="col3" colwidth="15mm" /><colspec colnum="4" colname="col4" colwidth="28mm" /><thead><row><entry morerows="1" align="center" valign="middle" /><entry namest="col2" nameend="col4" align="center" valign="middle">a*80</entry></row><row><entry align="center" valign="middle">L*</entry><entry align="center" valign="middle">b*</entry><entry align="center" valign="middle">Dilution degree</entry></row></thead><tbody><row><entry valign="middle">Solid solution type 1 (4%)</entry><entry align="center" valign="middle">64.80</entry><entry align="center" valign="middle">-26.99</entry><entry align="center" valign="middle">about 810-fold</entry></row><row><entry valign="middle">Solid solution type 2 (4%)</entry><entry align="center" valign="middle">61.50</entry><entry align="center" valign="middle">-35.96</entry><entry align="center" valign="middle">about 650-fold</entry></row><row><entry valign="middle">Single crystal PR122 (4%)</entry><entry align="center" valign="middle">57.33</entry><entry align="center" valign="middle">-29.93</entry><entry align="center" valign="middle">about 700-fold</entry></row><row><entry valign="middle">PV19 (4%)</entry><entry align="center" valign="middle">61.04</entry><entry align="center" valign="middle">-16.72</entry><entry align="center" valign="middle">about 500-fold</entry></row><row><entry valign="middle">PV32 (4%)</entry><entry align="center" valign="middle">49.51</entry><entry align="center" valign="middle">-38.60</entry><entry align="center" valign="middle">about 1500-fold</entry></row></tbody></tgroup></table></tables>

0061As shown in Table 2, in the solid solution types 1 and 2, when the a* value in a not more than 10000-fold diluted aqueous solution is 80, the L* value was not less than 60 and the b* value was not more than -17. By using the magenta ink composition according to the embodiment having such characteristics, in the recorded matter, color reproduction can be realized in a high L* value, a high a* value and a low b* value, color reproduction in a high-lightness red region is excellent, and color reproduction in a violet region is excellent.

[Embodiment C]

0062The magenta ink composition including the solid solution type 1 was prepared by the following composition.

<Type 1; Embodiment 1>

0063<tables id="tabl0007" num="0007"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="73mm" /><colspec colnum="2" colname="col2" colwidth="21mm" /><tbody><row><entry>Solid solution type 1</entry><entry align="right">3.0 wt %</entry></row><row><entry>Dispersing agent (styrene-acrylic acid copolymer)</entry><entry align="right">0.9 wt %</entry></row><row><entry>Glycerin</entry><entry align="right">14.0 wt %</entry></row><row><entry>1,2-hexanediol</entry><entry align="right">7.0 wt %</entry></row><row><entry>Triethanolamine</entry><entry align="right">0.9 wt %</entry></row><row><entry>KF-353A (made by Shin-Etsu Chemical Co., Ltd.)</entry><entry align="right">0.1 wt%</entry></row><row><entry>Ultrapure water</entry><entry align="right">Remainder</entry></row><row><entry>Total</entry><entry align="right">100.0 wt %</entry></row></tbody></tgroup></table></tables>

0064Instead of KF-353A (manufactured by Shin-Etsu Chemical Co., Ltd.) which is the surfactant of Embodiment 1, compositions of Embodiment 2 having the same composition except that 0.1 wt% of KF-945A (manufactured by Shin-Etsu Chemical Co., Ltd.) is used, Embodiment 3 having the same composition except that 0.07 wt% of AW-3 (manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.03 wt% of KF-6017 (manufactured by Shin-Etsu Chemical Co., Ltd.) are used, Embodiment 4 having the same composition except that 0.09 wt% of AW-3 (manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.01 wt% of X-22-6551 (manufactured by Shin-Etsu Chemical Co., Ltd.) are used, and Embodiment 5 having the same composition except that 0.1 wt% of SF-465 (manufactured by Shin-Etsu Chemical Co., Ltd.) is used were prepared.

(Evaluation of Gloss)

0065The obtained magenta ink compositions were charged in an ink jet printer PX-G900 (manufactured by Seiko Epson Corporation) and printing was performed on glossy paper <gloss> (manufactured by Seiko Epson Corporation) as an example of a medium having a coating layer, thereby obtaining recorded matters. In the printing, a duty was changed in a range of 5 to 100 (ink weight of 0.3 to 13 mg/inch²) such that the magenta ink was ejected.

0066With respect to the obtained recorded matters, the reflected light intensity having a reflection angle of 42 to 48 degrees was measured using automatic goniophotometer GP-200 (manufactured by MURAKAMI COLOR RESEARCH LABORATORY CO., Ltd.) at an incident angle of 45° (slit width; incident side ϕ1mm, reflection side ϕ1.5 mm), a sensitivity of 500, and a tilt angle of 0°. At this time, a halogen lamp (12 V, 50 W) as a light source and a ND-10 filter were used, and the voltage applied to the light source was adjusted to obtain a glossiness of the standard plate of 442.5. The maximum value of the reflected light intensity values measured under the conditions was designated as a maximum glossiness. The reproduction error was ±2.0 or less. The glossiness of the recorded matter was calculated by the following equation. <maths id="math0001" num=""><math display="block"><mi>Gloss</mi><mo>=</mo><mfenced><mi>glossiness</mi></mfenced><mo>/</mo><msup><mfenced><mi>image sharpness</mi></mfenced><mn>2</mn></msup></math><img file="EP1967558B2_D0005.tif" /></maths> Here, the glossiness indicates glossiness obtained by the measurement and the image sharpness indicates the degree of the image sharpness of the recorded image (also referred to as a representation property) and the width of the reflection angle having 0.6 or more among the values of the reflected light intensity measured when the glossiness is measured. The glossiness calculated in the above equation is appropriately matched to the evaluation of the glossiness by naked eyes. Evaluation criteria are as follows. The evaluated result is shown in Table 3. <ol id="ol0001" compact="compact" ol-style=""><li>A: maximum glossiness of 30 or more</li><li>B: maximum glossiness of less than 30</li></ol>

(Evaluation of Agglomeration Unevenness of Ink)

0067The obtained ink compositions were mounted in an ink cartridge of an ink jet printer (PX-G900, manufactured by Seiko Epson Corporation) and printing was performed on OK overcoat plus (manufactured by Oji Paper Co., Ltd.), which is print paper, with resolution of 2880x1440 dpi. At this time, as a printing condition, the ejection amount of ink was adjusted to become a dot weight of 7 ng in a single-direction recording method with resolution of 720×180 dpi by one-time driving of the recording head. The driving head is 200 cps. In the obtained recorded matters, agglomeration unevenness of the ink was evaluated by the following criteria. <ol id="ol0002" compact="compact" ol-style=""><li>A: The agglomeration unevenness is not present even in an ink weight of 3.6 mg/inch².</li><li>B: The agglomeration unevenness is not present even in an ink weight of 2.8 mg/inch².</li><li>C: The agglomeration unevenness is generated even in an ink weight of 2.8 mg/inch².</li></ol>

0068The evaluated result is shown in Table 3. <tables id="tabl0008" num="0008"><table frame="all"><title>[Table 3]</title><tgroup cols="3"><colspec colnum="1" colname="col1" colwidth="25mm" /><colspec colnum="2" colname="col2" colwidth="14mm" /><colspec colnum="3" colname="col3" colwidth="44mm" /><thead><row><entry align="center" valign="top" /><entry align="center" valign="top">Gloss</entry><entry align="center" valign="top">agglomeration unevenness</entry></row></thead><tbody><row><entry align="center">Embodiment 1</entry><entry align="center">A</entry><entry align="center">B</entry></row><row><entry align="center">Embodiment 2</entry><entry align="center">B</entry><entry align="center">A</entry></row><row><entry align="center">Embodiment 3</entry><entry align="center">A</entry><entry align="center">B</entry></row><row><entry align="center">Embodiment 4</entry><entry align="center">A</entry><entry align="center">A</entry></row><row><entry align="center">Embodiment 5</entry><entry align="center">B</entry><entry align="center">C</entry></row></tbody></tgroup></table></tables>

0069As shown in Table 3, in Embodiments 1 to 5, it can be seen that the gloss and the suppression of the agglomeration unevenness when recorded on print paper are compatible.

(Evaluation of Recorded Matter)

0070Next, instead of the solid solution type 1 of Embodiment 1, compositions of Embodiment 2 having the same composition except that the solid solution type 2 is used, Comparative example 1 having the same composition except that single crystal PR122 is used, Comparative example 2 having the same composition except that PV19 is used and Comparative example 3 having the same composition except that PV32 is used were prepared. The obtained magenta ink compositions of Embodiments 1 to 2 and Comparative examples 1 to 3 were charged in an ink jet printer PX-G900 (manufactured by Seiko Epson Corporation) and printing was performed on golly paper <gloss> manufactured by Seiko Epson Corporation) as an example of a medium having a coating layer, thereby obtaining recorded matters. In the printing, a duty was changed in a range of 5 to 100 (ink weight of 0.3 to 13 mg/inch²) such that the magenta ink was ejected. With respect to the obtained recorded matters, the L* value, the a* value and the b* value defined by CIE were measured by SPM-50 (manufactured by GretagMacbeth Corporation) with a D50 light source and a viewing angle of 2 degrees and without a filter. The result is shown in <figref idref="f0001">Figs. 1</figref> and <figref idref="f0002">2</figref>.

0071<ul id="ul0003" list-style="none" compact="compact"><li><figref idref="f0001">Fig. 1</figref> is a graph showing a relationship between a* values and b* values of recorded matters recorded using magenta ink compositions.</li><li><figref idref="f0002">Fig. 2</figref> is a graph showing a relationship between a* values and L* values of recorded matters recorded using magenta ink compositions.</li></ul>

0072As shown in <figref idref="f0002">Fig. 2</figref>, even in the recorded matter, color reproduction of a high L* value and a high a* value was excellent and color reproduction in the high-lightness red region was excellent. As shown in <figref idref="f0001">Figs. 1</figref> and <figref idref="f0002">2</figref>, in the recorded matter, color reproduction in the high-lightness red region having a high L* value and a high a* value was excellent and color reproduction in the violet region having a low b* value was excellent. That is, in the recorded matter, color reproduction can be realized with a high L* value, a high a* value and a low b* value.

[Embodiment D]

0073The magenta ink composition including the solid solution type 1 and the solid solution type 3 having a weight ratio of γ-type PV19 to PR202 of 40:60 was prepared as follows.

<Type 1; Embodiment 6>

(Preparation of Pigment kneaded material)

0074The solid solution type 1 was put in a sealing-system pressurizing kneader with the following composition ratio, kneading was for 10 hours at 130 °C and a pigment kneaded material was prepared. <tables id="tabl0009" num="0009"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="151mm" /><colspec colnum="2" colname="col2" colwidth="15mm" /><tbody><row><entry>Solid solution type 1</entry><entry align="right">20 wt%</entry></row><row><entry>Dispersing agent (styrene-acrylic acid copolymer; acid value 260, weight average molecular amount 18000,glass transition temperature 110 degrees)</entry><entry align="right">10 wt%</entry></row><row><entry>Glycerin</entry><entry align="right">15 wt%</entry></row><row><entry>Isopropyl alcohol</entry><entry align="right">4 wt%</entry></row><row><entry>Total</entry><entry align="right">49 wt%</entry></row></tbody></tgroup></table></tables>

0075Next, the following components were put in an agitator, overheating and agitation were performed for two hours at 130 °C, and a regulating solution before pigment dispersion was prepared.

(Preparation of Regulating Solution before Pigment Dispersion)

0076<tables id="tabl0010" num="0010"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="55mm" /><colspec colnum="2" colname="col2" colwidth="17mm" /><tbody><row><entry>Pigment kneaded material</entry><entry align="right">49 wt%</entry></row><row><entry>Triethanolamine (neutralizing agent)</entry><entry align="right">3 wt%</entry></row><row><entry>Deionized water</entry><entry align="right">48 wt%</entry></row><row><entry align="center">Total</entry><entry align="right">100 wt%</entry></row></tbody></tgroup></table></tables>

(Preparation of Regulating Material after Pigment Dispersion)

0077Next, the obtained regulating solution before pigment dispersion was put in a miniaturizable bead mill (having an organic pigment particle generation capability of 50 nm), dispersion was performed by 3-pass process, and a regulating material after pigment dispersion was prepared.

(Preparation of Pigment Dispersion Solution)

0078The obtained regulating material after pigment dispersion was adjusted to pH 8.5 with sodium hydroxide, centrifugal processing was performed for 5 minutes at 25000G to remove coarse particles, and regulation was performed by deionized water such that solid content becomes 10 wt%, thereby obtaining a pigment dispersion. The obtained pigment dispersion was a high-concentration coloring liquid composition, pH is 8.3, and a pigment particle diameter (volume 50% dispersion diameter) was 100 nm.

(Preparation of magenta Ink Composition)

0079The magenta ink composition was obtained by the following compositions. <tables id="tabl0011" num="0011"><table frame="none"><tgroup cols="2" colsep="0" rowsep="0"><colspec colnum="1" colname="col1" colwidth="43mm" /><colspec colnum="2" colname="col2" colwidth="20mm" /><tbody><row><entry>Pigment dispersion solution</entry><entry align="right">40.0 wt%</entry></row><row><entry>Glycerin</entry><entry align="right">14.0 wt%</entry></row><row><entry>1,2-hexanediol</entry><entry align="right">7.0 wt%</entry></row><row><entry>Triethanolamine</entry><entry align="right">0.9 wt%</entry></row><row><entry>BYK347</entry><entry align="right">0.1 wt%</entry></row><row><entry>Ultrapure water</entry><entry align="right">remainder</entry></row><row><entry align="center">Total</entry><entry align="right">100.0 wt%</entry></row></tbody></tgroup></table></tables>

<Type 3; Embodiment 7> (Preparation of Pigment Kneaded material)

0080A magenta ink composition including the solid solution type 3 was prepared similar to Embodiment 6, except that 20 wt% of solid solution type 3 having a weight ratio of γ-type PV19 to PR202 of 40:60 is used instead of 20 wt% of the solid solution type 1.

0081After the magenta ink compositions of Embodiments 6 and 7 are prepared, the ink compositions are diluted by water such that the a* value becomes 80. In an aqueous solution of Embodiment 6, about 820-fold dilution is required and, in an aqueous solution of Embodiment 7, about 640-fold dilution is required.

0082The measurement of the L* value, the a* value and the b* value of the aqueous solutions was performed using U3300 manufactured by Hitachi Ltd. In more detail, transmissivity was measured under the condition that a scan speed is 600 nm/min, a measurement wavelength range is 380 to 800 nm and a slit width is 2.0 nm and calculation is performed in a D65 light source and a viewing angle of 2 degrees. The result is shown in Table 4.

0083<tables id="tabl0012" num="0012"><table frame="all"><title>[Table 4]</title><tgroup cols="4"><colspec colnum="1" colname="col1" colwidth="25mm" /><colspec colnum="2" colname="col2" colwidth="14mm" /><colspec colnum="3" colname="col3" colwidth="15mm" /><colspec colnum="4" colname="col4" colwidth="26mm" /><thead><row><entry morerows="1" align="center" valign="top" /><entry namest="col2" nameend="col4" align="center" valign="top">a*80</entry></row><row><entry align="center" valign="top">L*</entry><entry align="center" valign="top">b*</entry><entry align="center" valign="top">Dilution degree</entry></row></thead><tbody><row><entry align="center">Embodiment 6</entry><entry align="center">64.60</entry><entry align="center">-26.25</entry><entry align="center">About 820-fold</entry></row><row><entry align="center">Embodiment 7</entry><entry align="center">61.80</entry><entry align="center">-36.80</entry><entry align="center">About 640-fold</entry></row></tbody></tgroup></table></tables>

0084As shown in Table 4, in Embodiments 6 and 7, when the a* value in a not more than 10000-fold dilution aqueous solution is 80, The L* value was not less than 60 and the b* value was not more than -17. By using the magenta ink composition of the embodiment having such characteristics, in the recorded matter, color reproduction can be realized in a high L* value, a high a* value and a low b* value, color reproduction in a high-lightness red region is excellent, and color reproduction in a violet region is excellent.

0085Next, the magenta ink compositions of Embodiments 6 and 7 were charged in an ink jet printer PX-G900 (manufactured by Seiko Epson Corporation) and printing was performed on glossy paper <gloss> (manufactured by Seiko Epson Corporation) as an example of a medium having a coating layer, thereby obtaining recorded matters. In the printing, a duty was changed in a range of 5 to 100 (ink weight of 0.3 to 13 mg/inch²) such that the magenta ink was ejected.

0086With respect to the obtained recorded matters, the L* value, the a* value and the b* value in the CIE standard were measured by SPM-50 (manufactured by GretagMacbeth Corporation) with a D50 light source and a viewing angle of 2 degree without a filter. Maximum a* values of the recorded materials are shown in Table 5.

0087<tables id="tabl0013" num="0013"><table frame="all"><title>[Table 5]</title><tgroup cols="2"><colspec colnum="1" colname="col1" colwidth="25mm" /><colspec colnum="2" colname="col2" colwidth="30mm" /><thead><row><entry align="center" valign="top" /><entry align="center" valign="top">Maximum a* value</entry></row></thead><tbody><row><entry align="center">Embodiment 6</entry><entry align="center">82.8</entry></row><row><entry align="center">Embodiment 7</entry><entry align="center">81.2</entry></row></tbody></tgroup></table></tables>

0088As shown in Table 5, in Embodiments 6 and 7, the a* value is not less than 80 and color development is excellent.

[Embodiment E]

<Type 2; Embodiment 8>

0089In Embodiment 4, the ink composition having the same composition was prepared except that the solid state type 2 is used instead of the solid solution type 1.

<Type 4; Embodiment 9>

0090In Embodiment 4, the ink composition having the same composition was prepared except that the solid solution type 4 in which a weight ratio of γ-type PV19 to PR202 is 65:35 is used instead of the solid solution type 1.

<Type 5; Embodiment 10>

0091In Embodiment 4, the ink composition having the same composition was prepared except that the solid solution type 5 in which a weight ratio of γ-type PV19 to PR202 is 60:40 is used instead of the solid solution type 1.

<Type 6; Embodiment 11>

0092In Embodiment 4, the ink composition having the same composition was prepared except that the solid solution type 6 in which a weight ratio of γ-type PV19 to PR202 is 50:50 is used instead of the solid solution type 1.

<Comparative Examples 1 and 2>

0093As Comparative Example 1, the ink composition having the same composition as Embodiment 4 was prepared except that single crystal PR122 is used instead of the solid solution type 1 and, as Comparative Example 2, the ink composition was prepared as Embodiment 4 except that PV19 is used instead of the solid solution type 1.

0094In the obtained ink compositions, agglomeration unevenness of the ink and gloss were evaluated by the same method as Embodiment C. The graininess, the color development of resin coated paper, and the color development of laser paper were evaluated by the following method.

[Evaluation of graininess]

0095The graininess is susceptible to be compared when the recording medium is coated by the ink by a half and the duty is generally 20% in resin coated paper. The duty of 20% of the magenta ink having a pigment concentration of 4% or less corresponds to the duty of a human skin because the lightness of resin coated paper is 50 to 70. Accordingly, if the type of the pigment which is the coloring material is different, the lightness of the duty of 20% is high. In addition, as the a* value is high, the graininess is excellent. That is, although the concentration of the coloring material is low, the color development can be maintained in the high a* value. Accordingly, it is possible to realize high lightness. In <figref idref="f0002">Fig. 2</figref>, a second plot from a side in which the a* value is low corresponds to the duty of 20%.

0096The ink compositions were recorded on resin coated paper by the known method and were evaluated by the following criteria. <ol id="ol0003" compact="compact" ol-style=""><li>A: When the duty is 20%, the lightness is not less than about 65 and the a* value is not less than about 55.</li><li>B: When the duty is 20%, the lightness is not less than about 65.</li><li>C: When the duty is 20%, the lightness is not more than about 65.</li></ol>

[Evaluation of Color Development of Resin Coated Paper (Color development of RC Paper)]

0097In an ideal magenta color in color reproduction of medium-lightness red and blue regions having an L* value of 40 to 60, the a* value is high when the L* value is 50 to 60 and the b* value is -15. The reason is because the lightness of the magenta color is generally lower than that of the yellow color and is equal to that of the cyan color as defined in JapanColor. Since the hue angle of the yellow ink jet ink is about 90 degrees and the hue angle of the cyan ink jet ink is about 240 degrees, it is preferable that the hue angle of the magenta ink jet ink is about 15 degrees from the viewpoint of the color development. In <figref idref="f0001">Fig. 1</figref>, a sixth plot from a side in which the a* value is low corresponds to the duty of 60%, a seventh plot corresponds to the duty of 70% and an eighth plot corresponds to the duty of 80%.

0098The ink compositions were recorded on resin coated paper by the known method and were evaluated by the following criteria. <ol id="ol0004" compact="compact" ol-style=""><li>A: When the b* value is -15, the a* value is not less than 80 and the duty at that time is about 60%.</li><li>B: When the b* value is -15, the a* value is not less than 80 and the duty at that time is about 70%.</li><li>C: When the b* value is -15, the a* value is not less than 80 and the duty at that time is about 80%.</li><li>D: When the b* value is -15, the a* value is less than 80.</li></ol>

(Color Development of Laser Paper)

0099Recently, like a print paper used in a catalog/pamphlet, an on-demand print of a double-sided printable recording medium with a waterproof property has come into wide use. This requirement can be preferably used in laser from the viewpoint of user utility. However, since a recording medium such as LPCCT (color laser paper) is hard to absorb the ink jet ink, the magenta ink including magenta pigment species developed with a small ink attachment amount is preferred. The obtained ink compositions were mounted in an ink cartridge of an ink jet printer (PX-G900, manufactured by Seiko Epson Corporation) and printing was performed on LPCCTA4 (manufactured by Oji Paper Co., Ltd.), which is print paper, with resolution of 2880×1440 dpi. At this time, as a printing condition, the ejection amount of ink was adjusted to become a dot weight of 7 ng in a single-direction recording method with resolution of 720×180 dpi by one-time driving of the recording head. The driving head is 200 cps.

0100The obtained recorded matters were evaluated by the following criteria. <ol id="ol0005" compact="compact" ol-style=""><li>A: The agglomeration unevenness is not present even in an ink weight of 5.6 mg/inch² and an OD(Dm) value is not less than 1.2.</li><li>B: The agglomeration unevenness is not present even in an ink weight of 5.6 mg/inch² and an OD(Dm) value is not less than 1.0 and is less than 1.2.</li><li>C: The agglomeration unevenness is generated even in an ink weight of 5.6 mg/inch² and an OD(Dm) value is less than 1.0.</li></ol> The evaluated result is shown in Table 6.

0101<tables id="tabl0014" num="0014"><table frame="all"><title>[Table 6]</title><tgroup cols="7"><colspec colnum="1" colname="col1" colwidth="26mm" /><colspec colnum="2" colname="col2" colwidth="18mm" /><colspec colnum="3" colname="col3" colwidth="13mm" /><colspec colnum="4" colname="col4" colwidth="20mm" /><colspec colnum="5" colname="col5" colwidth="27mm" /><colspec colnum="6" colname="col6" colwidth="30mm" /><colspec colnum="7" colname="col7" colwidth="35mm" /><thead><row><entry align="center" valign="middle" /><entry align="center" valign="middle">Magenta ink</entry><entry align="center" valign="middle">gloss</entry><entry align="center" valign="middle">graininess</entry><entry align="center" valign="middle">Color development of RC paper</entry><entry align="center" valign="middle">Agglomeration unevenness</entry><entry align="center" valign="middle">Color development of laser exclusive paper</entry></row></thead><tbody><row><entry align="center" valign="middle">Embodiment 4</entry><entry align="center" valign="middle">Solid solution type 1</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row><entry align="center" valign="middle">Embodiment 8</entry><entry align="center" valign="middle">Solid solution type 2</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">B</entry><entry align="center" valign="middle">C</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row><entry align="center" valign="middle">Embodiment 9</entry><entry align="center" valign="middle">Solid solution type 4</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row><entry align="center" valign="middle">Embodiment 10</entry><entry align="center" valign="middle">Solid solution type 5</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">B</entry><entry align="center" valign="middle">B</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row><entry align="center" valign="middle">Embodiment 11</entry><entry align="center" valign="middle">Solid solution type 6</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">B</entry><entry align="center" valign="middle">C</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">B</entry></row><row><entry align="center" valign="middle">Comparative Example 1</entry><entry align="center" valign="middle">PR122</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">C</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row><entry align="center" valign="middle">Comparative Example 2</entry><entry align="center" valign="middle">PV19</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">B</entry><entry align="center" valign="middle">D</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">B</entry></row></tbody></tgroup></table></tables>

0102As shown in Table 6, in Embodiment of using the solid solution such as γ-type PV19 and PR202, it can be seen that the gloss, graininess, color development of RC paper, the prevention of the agglomeration unevenness and color development of laser paper are compatible.

[Embodiment F]

<Embodiments 12 to 15>

0103The same ink composition as Embodiment 6 except that the solid solution type 2 is used instead of the solid solution type 1 was obtained (Embodiment 12). The same ink composition as Embodiment 6 except that the solid solution type 4 is used instead of the solid solution type 1 was obtained (Embodiment 13). The same ink composition as Embodiment 6 except that the solid solution type 5 is used instead of the solid solution type 1 was obtained (Embodiment 14). The same ink composition as Embodiment 6 except that the solid solution type 6 is used instead of the solid solution type 1 was obtained (Embodiment 15).

<Embodiments 16 to 21>

0104In Embodiment 6, an ink composition was obtained by the composition (total 100.0 wt%) including 40.0 wt% of solid solution type 1 which is dispersed by the known method (that is, is not kneaded), 14.0 wt% of glycerin, 7.0 wt% of 1,2-hexanediol, 0.9 wt% of triethanolamine, 0.1 wt% of BYK347, and ultrapure water (remainder) (Embodiment 16). In Embodiment 16, instead of the solid solution type 1, the ink compositions of Embodiment 17 having the same composition except that the solid solution type 3 is used, Embodiment 18 having the same composition except that the solid solution type 2 is used, Embodiment 19 having the same composition that the solid solution type 4 is used, Embodiment 20 having the same composition except that the solid solution type 5 is used, and Embodiment 21 having the same composition except that the solid solution type 6 is used were obtained.

<Embodiments 22 to 27>

0105In Embodiment 6, an ink composition was obtained by the composition (total 100.0 wt%) including 40.0 wt% of solid solution type 1 which is kneaded and dispersed and is subjected to the ultrafiltration classification process, 14.0 wt% of glycerin, 7.0 wt% of 1,2-hexanediol, 0.9 wt% of triethanolamine, 0.1 wt% of BYK347, and ultrapure water (remainder) (Embodiment 22). In Embodiment 22, instead of the solid solution type 1, the ink compositions of Embodiment 23 having the same composition except that the solid solution type 3 is used, Embodiment 24 having the same composition except that the solid solution type 2 is used, Embodiment 25 having the same composition that the solid solution type 4 is used, Embodiment 26 having the same composition except that the solid solution type 5 is used, and Embodiment 27 having the same composition except that the solid solution type 6 is used were obtained.

0106The obtained ink compositions were evaluated by the following method.

(Clogging Recovery Property)

0107The magenta ink compositions of Embodiments 6, 7 and 12 to 27 were charged in PX-G900 and the ink cartridge and the head are detached. This head was input by 40 degrees for one cycle. Thereafter, the head returned to an original state, a cleaning button was pressed eight times, and it is checked whether the ink can be ejected from all the nozzles. <ol id="ol0006" ol-style=""><li>A: All the nozzles are recovered.</li><li>B: All the nozzles are not recovered.</li></ol>

(Ejection Stability)

0108The magenta ink compositions of Embodiments 6, 7 and 12 to 27 were charged in PX-G900 and printing was performed under the condition of 40 degrees and 25% with a recording mode of a fast mode and general paper. <ol id="ol0007" compact="compact" ol-style=""><li>A: Omission is not present although printing is performed with respect to 1000 sheets of paper.</li><li>B: Omission is present when printing is performed with respect to 1000 sheets of paper.</li></ol> The result is shown in Table 7.

0109<tables id="tabl0015" num="0015"><table frame="all"><title>[Table 7]</title><tgroup cols="5"><colspec colnum="1" colname="col1" colwidth="27mm" /><colspec colnum="2" colname="col2" colwidth="32mm" /><colspec colnum="3" colname="col3" colwidth="24mm" /><colspec colnum="4" colname="col4" colwidth="43mm" /><colspec colnum="5" colname="col5" colwidth="28mm" /><thead><row><entry valign="middle" /><entry valign="middle">Magenta ink</entry><entry valign="middle">PV19:PR202</entry><entry valign="middle">Cogging recovery property</entry><entry valign="middle">Ejection stability</entry></row></thead><tbody><row rowsep="0"><entry valign="middle">Embodiment 6</entry><entry valign="middle">Solid solution type 1</entry><entry align="center" valign="middle">70:30</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">B</entry></row><row rowsep="0"><entry valign="middle">Embodiment 7</entry><entry valign="middle">Solid solution type 3</entry><entry align="center" valign="middle">40:60</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 12</entry><entry valign="middle">Solid solution type 2</entry><entry align="center" valign="middle">55:45</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 13</entry><entry valign="middle">Solid solution type 4</entry><entry align="center" valign="middle">65:35</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">B</entry></row><row rowsep="0"><entry valign="middle">Embodiment 14</entry><entry valign="middle">Solid solution type 5</entry><entry align="center" valign="middle">60:90</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">B</entry></row><row><entry valign="middle">Embodiment 15</entry><entry valign="middle">Solid solution type 6</entry><entry align="center" valign="middle">50:50</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 16</entry><entry valign="middle">Solid solution type 1</entry><entry align="center" valign="middle">70:30</entry><entry align="center" valign="middle">B</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 17</entry><entry valign="middle">Solid solution type 3</entry><entry align="center" valign="middle">40:60</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 18</entry><entry valign="middle">Solid solution type 2</entry><entry align="center" valign="middle">55:45</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 19</entry><entry valign="middle">Solid solution type 4</entry><entry align="center" valign="middle">65:35</entry><entry align="center" valign="middle">B</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 20</entry><entry valign="middle">Solid solution type 5</entry><entry align="center" valign="middle">60:90</entry><entry align="center" valign="middle">B</entry><entry align="center" valign="middle">A</entry></row><row><entry valign="middle">Embodiment 21</entry><entry valign="middle">Solid solution type 6</entry><entry align="center" valign="middle">50:50</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 22</entry><entry valign="middle">Solid solution type 1</entry><entry align="center" valign="middle">70:30</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 23</entry><entry valign="middle">Solid solution type 3</entry><entry align="center" valign="middle">90:60</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 24</entry><entry valign="middle">Solid solution type 2</entry><entry align="center" valign="middle">55:45</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row rowsep="0"><entry valign="middle">Embodiment 25</entry><entry valign="middle">Solid solution type 4</entry><entry align="center" valign="middle">65:35</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row><row><entry rowsep="0" valign="middle">Embodiment 26</entry><entry rowsep="0" valign="middle">Solid solution type 5</entry><entry rowsep="0" align="center" valign="middle">60:90</entry><entry rowsep="0" align="center" valign="middle">A</entry><entry rowsep="0" align="center" valign="middle">A</entry></row><row><entry valign="middle">Embodiment 27</entry><entry valign="middle">Solid solution type 6</entry><entry align="center" valign="middle">50:50</entry><entry align="center" valign="middle">A</entry><entry align="center" valign="middle">A</entry></row></tbody></tgroup></table></tables>

0110As shown in Table 7, in the solid solution in which the weight of PV19 is larger than that of PR202, it can be seen that the clogging recovery property and the ejection stability are excellent when the kneading process, the dispersion process and the classification process are performed.