JP2006274030A - Water-based pigment ink and method for ink-jet recording and record using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based pigment ink for ink-jet recording having excellent printing quality and water resistance and ensured jetting stability and preservation stability. <P>SOLUTION: The water-based pigment ink comprises at least water, a permeable organic solvent, a humectant and surface-treated pigment particles dispersible and/or soluble in water without a dispersing agent. The surface-treated pigment particles are prepared by binding hydrophilic dispersing groups to particles of a solid solution pigment composed of two or more kinds of molecular structures in one particle. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an aqueous pigment ink for ink jet recording, an ink jet recording method using the same, and a recorded matter.

  The ink jet recording method is a printing method in which printing is performed by causing a small droplet of an ink composition to fly and adhere to a recording medium such as paper. This method is characterized in that a high-resolution and high-quality image can be printed with low noise and high speed with a relatively inexpensive apparatus.

  The ink composition used in the ink jet recording method has water as a main component, a colorant, a humectant such as glycerin for the purpose of preventing clogging, and a surfactant or a water-soluble organic solvent as necessary, Or what contains antiseptic | preservative etc. is common. The colorant used in the ink composition for ink jet recording is a water-soluble dye because of the high saturation of the colorant, the abundance of types of colorants that can be used, and the ease of handling due to high solubility in water. Is used.

  However, the dye may be inferior in durability such as light resistance and water resistance, and thus inferior in light resistance and water resistance of a printed matter printed with the ink composition using the dye as a colorant.

  In contrast, pigments are superior in light resistance and water resistance compared to dyes. In recent years, pigments have been used as colorants in ink compositions for ink jet recording for the purpose of improving light resistance and water resistance. Is being considered.

  In order to stably disperse the pigment in the water-based ink, it is necessary to consider the type of pigment, the particle size, the type of dispersant used, the dispersing means, and the like. Has been proposed. For example, an aqueous pigment ink in which carbon black is dispersed with a surfactant or a polymer dispersant is known (see Patent Document 1 and Patent Document 2).

  Various techniques have also been proposed for imparting water dispersibility to the pigment itself without using the dispersant as described above. For example, the carbon black surface is oxidized by hypochlorous acid or ozone to impart dispersibility. As a technique for imparting dispersibility to an organic pigment, for example, an organic pigment dispersed in a solvent having no active proton is treated with a sulfonating agent. A method for obtaining a sulfonated surface-treated organic pigment (see Patent Document 5), and other organic pigment lumps that positively charge the surface by treating the sulfonic acid group-introduced organic pigment lumps with monovalent metal ions A water-based ink composition having excellent storage stability, comprising pigment fine particles prepared from the surface positively charged organic pigment mass, a dispersant, and water (see Patent Document 6). There has been described.

JP-A 64-6074 JP-A 64-31881 JP-A-8-3498 JP-A-10-204341 Japanese Patent Laid-Open No. 10-110129 JP-A-11-49974

  As described above, in order to use a pigment in an ink composition for ink jet recording, it is important to stably disperse a pigment as a colorant in an aqueous ink and maintain it for a long time. The technology (Patent Documents 1 to 6) was not fully satisfactory.

  As described above, in order to optimize various properties in the ink jet recording method, various additives, in particular, surfactants and water-soluble organic solvents are added to the ink composition for ink jet recording. The Examples of the water-soluble organic solvent include a humectant that prevents drying, and a penetrating solvent that lowers the surface tension of the ink composition and controls the permeability to the recording medium. When these surfactants and solvents are present in the ink, they may affect the pigment as a colorant to inhibit the dispersibility of the ink composition, thereby reducing the storage stability of the ink composition. In particular, when the pigment is dispersed by physically adsorbing the dispersant on the pigment surface (Patent Document 1 and Patent Document 2), other surfactants having a high affinity for the dispersant and the dispersion resin are used. Such an effect is likely to occur by using an additive. In addition, the dispersant is released from the pigment surface and the pigment is aggregated in the ink, or the further dispersed resin is dissolved in the ink, which becomes clogged in the nozzles of the ink jet head and makes ink ejection unstable. There was a problem.

  Further, in the method of imparting dispersibility directly to the pigment surface, there is a problem that the treatment has a considerable influence on the pigment molecules.

  In particular, it is difficult to impart dispersibility to the organic pigment by the surface treatment as described above. For example, a method of imparting hydrophilicity by oxidation treatment (Patent Document 3 and Patent Document 4) uses the structure of pigment molecules by oxidation treatment. Therefore, it is difficult to put it into practical use with an organic pigment, and it has been limited to inorganic pigments such as carbon black.

  Further, in the method of introducing a sulfone group to the surface of the organic pigment (Patent Document 5, Patent Document 6), it is difficult to control the treatment, for example, if the treatment conditions are weak, sufficient dispersibility of the pigment cannot be obtained, When processing conditions are strengthened, sulfone groups are introduced to the surface of the pigment more than necessary and the pigment dissolves (dyes), and further affects the molecular structure of the pigment, especially when the coloring group is affected. Has problems such as impairing the color development of the pigment.

  Therefore, the present invention solves the above-mentioned problems, and in the surface-treated pigment particles, it imparts necessary and sufficient dispersibility to the pigment while minimizing the influence on the molecular structure of the pigment particles. That is, the present invention provides a surface-treated pigment that is stably dispersed in an ink.

  That is, an object of the present invention is to provide an ink composition that ensures water resistance, light resistance, ink ejection stability and storage stability.

  The water-based ink composition of the present invention is a water-based pigment ink comprising at least water, a permeable organic solvent, a humectant, and surface-treated pigment particles that can be dispersed and / or dissolved in water without a dispersant. The surface-treated pigment particles are characterized in that a hydrophilic dispersion group is bonded to particles of a solid solution pigment containing two or more pigments having different molecular structures in one particle.

  Further, the surface-treated pigment particles are obtained by bonding a hydrophilic dispersion group to solid solution pigment particles composed of two or more kinds of organic pigments having different molecular structures in one particle, and organic particles in the solid solution pigment particles. At least one type of pigment is characterized by having a halogen group on the surface.

  Further, the organic pigment having a halogen group in the solid solution pigment particle is characterized in that a dispersing group is not bonded to at least one kind.

  The permeable organic solvent is selected from the group consisting of glycol monoether derivatives of polyhydric alcohols, 1,2-alkyldiols, and derivatives having a 1,3-propanediol skeleton.

  Further, two or more types of organic pigments having different molecular structures have the same basic molecular skeleton.

  Next, the present invention will be described in detail with reference to preferred embodiments.

[Surface treatment solid solution pigment particles]
The ink composition of the present invention is a self-dispersing type in which a sulfonic acid group is introduced into particles of a solid solution pigment containing two or more types of pigments having different molecular structures in one pigment particle, and dispersed in an aqueous medium without a dispersant. The surface-treated pigment particles are preferably contained.

  The solid solution pigment in the present invention refers to a pigment that exists as a mixed crystal (a state crystallized in a mixed state) of a plurality of pigment molecules, and thus differs from a case where two or more types of pigments are simply mixed. . For example, JP-A-60-35055 and JP-A-2-38463 describe methods for producing solid solution pigments.

  Confirmation of the formation of the solid solution pigment can be easily confirmed by X-ray diffraction analysis. In the case of a simple mixture, a pattern corresponding to the superposition of the respective X-ray diffraction patterns is obtained as the X-ray diffraction pattern, and the peak intensity is proportional to the blending ratio. On the other hand, when a solid solution is formed, a diffraction pattern unique to the newly formed crystal is shown.

  Examples of the organic pigment that can be used in the present invention include azo pigments such as insoluble monoazo pigments, insoluble disazo pigments, condensed azo pigments and metal complex azo pigments, and also phthalocyanine pigments and condensed polycyclic pigments. Anthraquinone pigments, thioindigo pigments, perinone pigments, perylene pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments, quinophthalone pigments, isoindoline pigments, and the like, and nitroso pigments, alizarin lake pigments, metal complex azomethine pigments Etc.

  More specific examples of the pigment used in the present invention include insoluble azo pigments such as β-naphthol-based insoluble monoazo pigments, C.I. I. Pigment Red 1, 3, 4, 6, C.I. I. Pigment Orange 2, 5 and the like, and naphthol AS-based insoluble monoazo pigments include C.I. I. Pigment Red 171, 175, 176, 185, 208, C.I. I. Pigment violet 32, C.I. I. Pigment Brown 25 and the like. As an acetoacetic acid arylamide-based insoluble monoazo pigment, C.I. I. Pigment Yellow 1, 3, 4, 4, 6, 65, 73, 74, 75, 97, 98, 116, C.I. I. Pigment Orange 1 and the like, and benzimidazolone-based insoluble monoazo pigments include C.I. I. Pigment yellow 120, 151, 154, C.I. I. And CI Pigment Orange 36. Examples of insoluble disazo pigments include acetoacetic acid annealed amide-based insoluble disazo pigments such as C.I. I. Pigment Yellow 12, 13, 14, 15, 16, 17, 55, 81, 83, 87, 113, 124, 170, 171, 172, C.I. I. Pigment Orange 14, 15, 16 and the like, and pyrazolone-based insoluble disazo pigments include C.I. I. Pigment orange 13, 34, C.I. I. Pigment Red 37, 38, 41, 42 and the like. Examples of the condensed azo pigment include C.I. acetoacetate arylamide-based condensed azo pigments. I. Pigment Yellow 93, 94, 95, and the like. As naphthol-based condensed azo pigments, C.I. I. Pigment orange 31, C.I. I. Pigment red 144, 166, and the like, and examples of the metal complex salt azo pigment include C.I. I. Pigment green 10, C.I. I. And CI Pigment Brown 2. Examples of the phthalocyanine pigment include C.I. I. Pigment Blue 15: 1, 15: 2, 15: 3, 15: 4, 15: 6, 16 and C.I. I. Pigment Green 7, 36, 37, and the like. Examples of the anthraquinone pigment include C.I. I. Pigment yellow 24, 108, 123, C.I. I. Pigment orange 40, C.I. I. Pigment red 168, 177, C.I. I. Pigment blue 64, C.I. I. Pigment Green 47 and the like. Examples of the thioindigo pigment include C.I. I. Pigment red 88, and as perinone pigments, C.I. I. Pigment orange 43, C.I. I. Pigment Red 194 and the like. Examples of perylene pigments include C.I. I. Pigment Red 123, 149, 178, 179, 189, 190, 224, C.I. I. Pigment brown 26 and the like, and examples of the quinacridone pigment include C.I. I. Pigment Red 122, 206, 207, 209, C.I. I. Pigment violet 19 and the like. Examples of the dioxazine pigment include C.I. I. Pigment Violet 23, and examples of the isoindolinone pigment include C.I. I. Pigment yellow 109, 110, C.I. I. Pigment orange 42, C.I. I. Pigment Red 180 and the like, and examples of the quinophthalone pigment include C.I. I. Pigment Yellow 138 and the like, and examples of the isoindolinone pigment include C.I. I. Pigment Yellow 139 and the like. Examples of the nitroso pigment include C.I. I. Pigment Yellow 153 and the like, and examples of the metal azomethine pigment include C.I. I. And CI Pigment Yellow 117.

  The ink used in the present invention can be used by surface-treating a solid solution obtained by combining two or more of the above pigments. In particular, it is preferable to use a solid solution in which two or more pigments having the same basic molecular structure are combined.

In the surface-treated pigment in the present invention, it is preferable to introduce a dispersing group into the pigment particles with a surface treatment agent containing sulfur. As such a dispersing group, a functional group that contains a sulfur atom and imparts dispersibility in water. The group is not particularly limited as long as it is a group, and specific examples include a sulfinic acid (SO ₂ ⁻ ) group or a sulfonic acid (SO ₃ ⁻ ) group. In the pigment particle, it is sufficient that the above-mentioned dispersing group is present in a necessary amount at least on the particle surface, and may be contained inside the particle.

  The surface-treated pigment contained in the ink used in the present invention can be prepared from the above-mentioned solid solution pigment by a known method. For example, in the form of an aqueous dispersion prepared by the method described in JP-A-8-283596, JP-A-10-110110, JP-A-10-110111, or JP-A-10-110114, a dispersing group Can be obtained on the surface.

  The introduction amount of the dispersing group in the surface-treated pigment contained in the ink used in the present invention is preferably 1 to 2 in terms of one molecule of pigment, and more preferably in terms of one molecule of pigment. 1.2 to 1.8.

  In the experiments by the present inventors, when the amount of the dispersing group introduced is less than 1 per pigment molecule, sufficient dispersibility cannot be imparted to the pigment particles, and aggregation of the pigment particles occurs. It was confirmed that the storage stability of the ink was lowered. In addition, when the amount of the dispersibility-imparting group introduced is 2 or more per pigment molecule, the pigment is converted into a dye and sufficient water resistance cannot be obtained, or foreign matter of the surface-treated pigment is generated, resulting in ink storage. It was confirmed that the stability decreased.

  Specific examples of the surface-treated pigment according to the present invention include C.I. which is a quinacridone pigment. I. Pigment Red 122 at 60%, C.I. I. It can be obtained by performing surface treatment on a solid solution pigment in which CI Pigment Red 209 is combined at a ratio of 40%.

  In the following formula (I), C.I. I. The molecular structure of CI Pigment Red 122 is shown. For example, C.I. I. When the surface treatment is performed on the pigment particles of only pigment red 122, a dispersibility-imparting group is introduced at positions a and b that are energetically the same. As described above, when two or more dispersibility-imparting groups are introduced per pigment molecule, it becomes difficult to obtain storage stability. However, C.I. I. Since Pigment Red 122 has two energetic isotopes like a and b, it is difficult to control the reaction conditions when introducing a dispersing group into only one of them, and usually two dispersibility-imparting groups are present. It will be introduced into the molecule.

  The following formula (II) is C.I. I. The molecular structure of CI Pigment Red 209 is shown. C. I. In the case of Pigment Red 209, an electron-withdrawing chlorine group (halogen group) is present in the pigment molecule. I. Compared to Pigment Red 122, C.I. I. It is difficult for a dispersing group to be introduced at positions c and d of Pigment Red 209. Therefore, as described above, C.I. I. Pigment red 122 and C.I. I. When the surface treatment of the solid solution pigment particles combined with Pigment Red 209 is performed, C.I. I. A dispersibility-imparting group is introduced only at positions a and b of CI Pigment Red 122; I. Since it is difficult to introduce a dispersing group into the pigment red 209 molecule, one or two dispersibility-imparting groups can be introduced into the pigment particle relatively easily per pigment molecule.

  Also, it is not a pigment solid solution, but simply C.I. I. Pigment red 122 and C.I. I. When the surface treatment was similarly performed with the mixture of Pigment Red 209, it was confirmed that the storage stability of the surface-treated pigment particles in the ink was extremely deteriorated because the intermolecular force between different pigments was weak. .

  The average particle size of the pigment particles contained in the ink used in the present invention is not particularly limited, but is preferably 10 to 200 nm, and preferably 50 nm to 150 nm. If the average particle size is less than 10 nm, the light resistance may be lost, and if it exceeds 200 nm, it may settle and stable ejection may not be achieved.

[Acetylene glycol surfactant]
In the water-based pigment ink according to the present invention, a surfactant made of acetylene glycol or an ether derivative thereof can be added. The acetylene glycol surfactant is used for increasing the ink permeability to the recording medium. In addition, the acetylene glycol nonionic surfactant has a property of having little or no foaming property and is particularly useful when the water-based pigment ink of the present invention is used in an ink jet recording method. Specific examples of acetylene glycol-based nonionic surfactants preferable in the present invention include Air Products and Chemicals. Inc. Surfynol 61, 82, 104, 440, 465, 485, or TG, manufactured by Nissin Chemical Industry Co., Ltd., Olfin STG, Olfin E1010, etc., acetylenol E00, acetylenol E00P, acetylenol E40 manufactured by Kawasaki Fine Chemical Co., Ltd. Examples include acetylenol E100.

  The addition amount of the acetylene glycol-based nonionic surfactant may be appropriately determined depending on the desired ink drying time, but is preferably 0.01% by weight to 10% by weight with respect to the total amount of the ink.

[Humectant]
The water-based pigment ink according to the present invention contains a moisturizing agent, and the moisturizing agent suppresses drying of the ink, thereby suppressing moisture evaporation due to drying of the tip of the printer head nozzle and preventing aggregation and solidification of the ink composition. To be added.

  The humectant is selected from water-soluble and highly hygroscopic materials such as glycerin, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, polypropylene glycol, 1,3-propanediol. 1,4-butanediol, 1,5-pentanediol, 2,3-butanediol, 2-methyl-2,4-pentanediol, 1,2,6-hexanetriol, polyols such as pentaerythritol, 2 -Lacrams such as -pyrrolidone and N-methyl-2-pyrrolidone and ureas such as 1,3-dimethylimidazolidinone can be used.

  Furthermore, a water-soluble solid moisturizing agent can be used in combination and added for the purpose of assisting the ability of the above-described moisturizing organic solvent. Specifically, diols such as 1,6-hexanediol, 1,8-octanediol, 2,2-dimethyl-1,3-propanediol, and 2,2-diethyl-1,3-propanediol, trimethylolethane , Trimethylolpropane and the like, lactams such as ε-caprolactam, urea derivatives such as urea, thiourea and ethylene urea, glucose, mannose, fructose, ribose, xylose, arabinose, galactose, aldonic acid, glucitol, (sorbitol), maltose Monosaccharides such as cellobiose, lactose, sucrose, trehalose, maltotriose, disaccharides, oligosaccharides and polysaccharides and derivatives of these saccharides include reducing sugars, oxidized sugars, amino acids, thiosaccharides, etc. Can be mentioned. Sugar alcohol is particularly preferable, and specific examples include maltitol and sorbit.

  The addition amount of these humectants is preferably 1% by weight to 40% by weight, more preferably 1% by weight to 30% by weight, based on the total amount of ink, alone or in combination. These humectants can be added together with other ink additives in an addition amount that results in an ink viscosity of 25 cPs or less at 25 ° C.

[Penetration organic solvent]
The water-based pigment ink according to the present invention contains a permeable organic solvent in which acetylene glycol or an ether derivative thereof is mutually dissolved. Furthermore, the permeable organic solvent is more preferably selected from glycol monoether derivatives of polyhydric alcohols, 1,2-alkyldiols, and derivatives having a 1,3-propanediol skeleton.

  As the glycol monoether derivative of polyhydric alcohol, a derivative of polyhydric alcohol having 3 or more carbon atoms in alkyl is particularly preferable. Specifically, ethylene glycol monobutyl ether, diethylene glycol mono-n-propyl ether, ethylene glycol mono-iso-propyl ether, diethylene glycol mono-iso-propyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol mono-t-butyl ether Diethylene glycol mono-n-butyl ether, triethylene glycol mono-n-butyl ether, diethylene glycol mono-t-butyl ether, 1-methyl-1-methoxybutanol, propylene glycol mono-t-butyl ether, propylene glycol mono-n-propyl ether, Propylene glycol mono-iso-propyl ether, propylene glycol mono-n-butyl ether, dipropylene Glycol mono -n- butyl ether, di-propylene glycol mono -n- propyl ether, dipropylene glycol monomethyl -iso- propyl ether. The addition amount of the glycol monoether derivative of the polyhydric alcohol is preferably in the range of 0.5 to 15% by weight with respect to the total amount of the aqueous ink composition.

  As the 1,2-alkyldiols, 1,2-alkyldiols having 4 to 8 carbon atoms such as butanediol, pentanediol, hexanediol, heptanediol, and octanediol are preferable. C6-C8 1,2-hexanediol, 1,2-heptanediol, and 1,2-octanediol are particularly preferred because of their high permeability to recording media. The addition amount of these 1,2-alkyldiols is preferably in the range of 0.25 wt% to 15 wt% with respect to the total amount of the aqueous ink composition.

  Examples of derivatives having a 1,3-propanediol skeleton include 2- (2,2-diethoxyethyl) -1,3-propanediol, 2-ethyl-2-hydroxymethyl-1,3-propanediol, 2, 2-dimethyl-1,3-propanediol, 2,2-diethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 2,2 ′-[oxybis (methylene)] bis [2-ethyl-1,3-propanediol] and the like are particularly preferable. The amount of the derivative having a 1,3-propanediol skeleton is preferably added in the range of 0.25 wt% to 15 wt% with respect to the total amount of the aqueous ink composition.

[Additive resin]
In the water-based pigment ink according to the present invention, a resin can be added for the purpose of improving the fixability and glossiness of the recorded matter recorded with the present ink. As such an added resin, a water-soluble resin and / or a water-dispersible resin can be used. Alternatively, it can be added as a resin emulsion of a single resin.

The additive resin used in the present invention is particularly preferably blended in the ink composition in the form of resin fine particle emulsion. The reason is that a water-soluble resin has a high rate of increase in the viscosity of the ink relative to the added amount of the resin, and it is difficult to add a resin amount that can sufficiently improve the fixability and gloss characteristics. Further, even if the resin fine particles are added to the ink composition as they are, dispersion of the resin particles may be insufficient, so that the emulsion form is preferable for the production of the ink composition.
Examples of such resin emulsions include acrylic resins, vinyl acetate resins, vinyl chloride resins, styrene-acrylic resins, and the like. These resins have a single-phase structure and a multiphase structure (core-shell type). Any of these can be used.

  The emulsion of resin fine particles can be obtained by a known emulsion polymerization method. For example, it can be obtained by emulsion polymerization of an unsaturated monomer (such as an unsaturated vinyl monomer) in water containing a polymerization initiator and a surfactant.

  Examples of unsaturated monomers include acrylic acid ester monomers, methacrylic acid ester monomers, aromatic vinyl monomers, vinyl ester monomers, vinyl cyanide compounds generally used in emulsion polymerization. Examples include monomers, halogenated monomers, olefin monomers, and diene monomers. In addition to the polymerization initiator and surfactant used in emulsion polymerization, a chain transfer agent, further a neutralizing agent, and the like may be used according to a conventional method. In particular, ammonia and inorganic alkali hydroxides such as sodium hydroxide and potassium hydroxide are preferred as the neutralizing agent.

  On the other hand, when the average particle size of the resin fine particles in the present invention is in the range of 100 nm to 300 nm, the coloring material is retained on the paper surface and the effect of improving the color developability is exhibited, and the bleeding can be suppressed.

  In the present invention, the resin fine particles are within the range of 0.5 to 10% by weight from the viewpoint of more effectively obtaining the ink jet proper physical property value, reliability (clogging, ejection stability, etc.) and the effect of the present invention. It is preferably contained in the ink composition.

[water]
Water is a central medium of the water-based pigment ink of the present invention, and preferable water is ion-exchanged water, ultrafiltered water, reverse osmosis water, distilled water, etc. for the purpose of reducing ionic impurities as much as possible. Pure water or ultrapure water can be used.

  In addition, when water sterilized by ultraviolet irradiation or addition of hydrogen peroxide is used, it is preferable because generation of mold and bacteria can be prevented when the ink composition is stored for a long period of time.

[Other ingredients]
The water-based pigment ink of the present invention may further contain additives that are usually used in ink jet recording inks, if necessary.

  Additives added as necessary include surfactants, hydrotropic agents, antioxidants / ultraviolet absorbers, preservatives / fungicides, and the like.

  The surfactant is an additive for increasing the ink permeability to the recording medium.

  Suitable materials include anionic surfactants such as fatty acid salts and alkyl sulfate esters, nonionic surfactants such as polyoxyethylene alkyl ether and polyoxyethylene phenyl ether, acetylene glycol-based nonionic surfactants, and cationic surfactants. Surfactants, amphoteric surfactants, silicon surfactants, phosphorus surfactants, boron surfactants, and the like can be used.

  The hydrotropic agent is added to improve the storage stability and clogging resistance of the ink, and urea, thiourea, alkylurea, etc. can be used.

  Antioxidants and ultraviolet absorbers include allophanates such as allophanate and methyl allophanate, biurets such as biuret, dimethylbiuret and tetramethylbiuret, L-ascorbic acid and its salts, etc., Tinuvin 328, 900 manufactured by Ciba Geigy 1130, 384, 292, 123, 144, 622, 770, 292, Irgacor 252, 153, Irganox 1010, 1076, 1035, MD1024 or the like, or a lanthanide oxide or the like is used.

  Examples of preservatives and fungicides include sodium benzoate, sodium pentachlorophenol, sodium 2-pyridinethiol-1-oxide, sodium sorbate, sodium dehydroacetate, 1,2-benzisothiazolin-3-one, etc. You can choose from.

[Inkjet recording method and recorded matter]
As the ink jet recording method of the present invention, any method can be used as long as it is a system in which the above-mentioned aqueous pigment ink composition is ejected as droplets from a fine nozzle and the droplets are attached to a recording medium. To explain some of them, there is an electrostatic attraction method. In this method, a strong electric field is applied between the nozzle and the acceleration electrode placed in front of the nozzle, and ink is continuously ejected in the form of droplets from the nozzle. There are a method of recording by supplying a printing information signal to the deflection electrode while the ink droplet flies between the deflection electrodes, or a method of ejecting the ink droplet corresponding to the printing information signal without deflecting the ink droplet.

  The second method is a method in which ink droplets are forcibly ejected by applying pressure to the ink liquid with a small pump and mechanically vibrating the nozzle with a crystal resonator or the like. The ejected ink droplet is charged simultaneously with the ejection, and a printing information signal is given to the deflection electrode and recorded while the ink droplet flies between the deflection electrodes.

  The third method is a method using a piezoelectric element, in which a pressure and a print information signal are simultaneously applied to an ink liquid by a piezoelectric element to eject and record ink droplets.

  The fourth method is a method in which the ink liquid is rapidly expanded in volume by the action of heat energy, and the ink liquid is heated and foamed with a microelectrode in accordance with a print information signal to eject and record ink droplets.

  Of the various ink jet recording methods as described above, ink adhesion to the discharge nozzle is prevented by combining the printing method at a relatively low ink discharge speed of around 10 m / s and the aqueous ink composition of the present invention. Ink jet recording can be performed stably, which is preferable.

  The recorded matter of the present invention can be obtained by printing the above-described aqueous pigment ink by an ink jet recording method.

  The contents of the present invention will be clearly described by the following examples, but the scope of the present invention is not limited to the following examples. Moreover, the dispersion used for the water-based pigment ink of the present invention was prepared by the following method.

(1) Production of surface-treated quinacridone solid solution pigment In this example, quinacridone pigment C.I. I. Pigment red 122 and C.I. I. A quinacridone solid solution pigment prepared by mixing Pigment Red 209 at a ratio of 60:40 was used. The confirmation of the solid solution formation of the product was confirmed by X-ray diffraction to be different from the diffraction pattern of the mixture.
15 parts of the quinacridone solid solution pigment was mixed with 450 parts of quinoline, and sized and dispersed for 2 hours using an Eiger motor mill M250 type (manufactured by Eiger Japan) at a bead filling rate of 70% and a rotational speed of 5000 rpm. The mixture of the pigment paste and the solvent was transferred to an evaporator, heated to 120 ° C. while reducing the pressure to 30 mmHg or less, and water contained in the system was distilled off as much as possible, and the temperature was controlled at 160 ° C. Next, 20 parts of a sulfonated pyridine complex was added and reacted for 8 hours. After completion of the reaction, the mixture was washed several times with excess quinoline, poured into water, and filtered through a Buchner funnel to obtain a surface-treated quinacridone solid solution pigment.

(2) Production of Pigment Dispersion Add 15 parts of triethanolamine and 83 parts of ion-exchanged water as a neutralizing agent to 15 parts of the surface-treated quinacridone solid solution pigment obtained in Example 1 (1), and use a paint shaker (using glass beads; Using a bead filling ratio = 60%; media diameter = 1.7 mm), the pigment was dispersed until the average particle diameter (secondary particle diameter) of the pigment reached 95 nm to obtain a surface-treated quinacridone pigment dispersion.

(3) Preparation of Ink for Inkjet Recording With respect to 40 parts of the surface-treated quinacridone pigment dispersion obtained in Example 1 (2), 0.1 part of Surfinol 104, 0.4 part of Surfinol 465, By gradually adding 5 parts of ethylene glycol monobutyl ether, 10 parts of glycerin, 5 parts of triethylene glycol and 44.5 parts of ion-exchanged water while stirring, the ink of Example 1 according to the present invention (pigment concentration 6%) Got.
The additive composition is shown below.
Pigment dispersion 40 parts Surfinol 104 0.1 parts Surfinol 465 0.4 parts Triethylene glycol monobutyl ether 5 parts Glycerin 10 parts Triethylene glycol 5 parts Ion-exchanged water 34.5 parts

(1) Production of surface-treated phthalocyanine solid solution pigment In this example, C.I. I. Pigment blue 15: 3 and C.I. I. A phthalocyanine solid solution pigment prepared by mixing Pigment Green 37 in a ratio of 50:50 was used. The confirmation of the solid solution formation of the product was confirmed by X-ray diffraction to be different from the diffraction pattern of the mixture.
20 parts of the above phthalocyanine solid solution pigment is mixed with 500 parts of quinoline and sized and dispersed for 2 hours under conditions of 70% bead filling and 5000 rpm with an Eiger motor mill M250 type (manufactured by Eiger Japan Co., Ltd.). The mixture of the pigment paste and the solvent thus prepared was transferred to an evaporator, heated to 100 ° C. while reducing the pressure to 30 mmHg or less, and water contained in the system was distilled off as much as possible, and the temperature was controlled at 150 ° C. Next, 20 parts of a sulfonated pyridine complex was added as a reactant and reacted for 4 hours. After completion of the reaction, the mixture was washed several times with excess quinoline, poured into water, and filtered through a Buchner funnel to obtain a surface-treated phthalocyanine solid solution pigment. Obtained.

(2) Production of pigment dispersion To 10 parts of the surface-treated phthalocyanine solid solution pigment obtained in Example 2 (1), 2 parts of propanolamine and 88 parts of ion-exchanged water were added as a neutralizing agent, and a paint shaker (using glass beads; A surface-treated phthalocyanine pigment dispersion was obtained by dispersing using a bead filling ratio = 60%; media diameter = 1.7 mm) until the average particle diameter (secondary particle diameter) of phthalocyanine reached 90 nm.

(3) Preparation of ink for ink jet recording For 50 parts of the surface-treated phthalocyanine pigment dispersion obtained in Example 2 (2), 0.5 part of Surfynol 82, 2 parts of propylene glycol monobutyl ether, 1, By gradually adding 3 parts of 2-pentanediol, 15 parts of glycerin, 0.5 part of triethanolamine and 49 parts of ion-exchanged water while stirring, the ink of Example 2 according to the present invention (pigment concentration 5%) )
The additive composition is shown below.
Pigment dispersion 50 parts Surfynol 82 0.5 parts Propylene glycol monobutyl ether 2 parts 1,2-pentanediol 3 parts Glycerin 15 parts Triethanolamine 0.5 part Ion-exchanged water 29 parts

(1) Production of surface-treated acetoacetic acid arylamide-based insoluble monoazo solid solution pigment In this example, C.I. I. Pigment Yellow 1 and C.I. I. An insoluble monoazo solid solution pigment of acetoacetic acid arylamide prepared by mixing Pigment Yellow 98 in a ratio of 50:50 was used. The confirmation of the solid solution formation of the product was confirmed by X-ray diffraction to be different from the diffraction pattern of the mixture.
A surface-treated acetoacetate arylamide-based insoluble monoazo solid solution pigment was obtained by repeating the procedure described in Example 1 (1) except that the solid solution pigment to be treated was an acetoacetate arylamide-based insoluble monoazo solid solution pigment.

(2) Dispersion process (process B)
To 15 parts of the surface-treated acetoacetic acid arylamide-based insoluble monoazo solid solution pigment obtained in Example 3 (1), 2 parts of 2-amino-2-methyl-1-propanol and 83 parts of ion-exchanged water were added as neutralizing agents. A surface-treated aryl acetoacetate was dispersed by using a paint shaker (glass beads used; bead filling ratio = 60%; media diameter = 1.7 mm) until the average particle diameter (secondary particle diameter) of dimethylquinacridone reached 100 nm. An amide-based insoluble monoazo pigment dispersion was obtained.

(3) Preparation of inkjet recording ink 1 part of Surfinol 485 (manufactured by Air Products), 1 part of 60 parts of the surface-treated acetoacetic acid arylamide-based insoluble monoazo pigment dispersion obtained in Example 3 (2), , 2-hexanediol 5 parts, glycerin 15 parts, triethanolamine 1 part, and ion-exchanged water 18 parts were gradually added with stirring to obtain the ink of Example 3 (pigment concentration 6%) according to the present invention. .
The additive composition is shown below.
Pigment dispersion 40 parts Surfinol 485 1 part Diethylene glycol monobutyl ether 3 parts 1,2-hexanediol 2 parts Glycerin 15 parts Triethanolamine 1 part Ion-exchanged water 38 parts

(Comparative Example 1)
(1) Production of surface-treated quinacridone pigment In this comparative example, C.I. I. Pigment red 122 and C.I. I. Pigment Red 209 was simply mixed at a ratio of 60:40.
The pigment to be treated is C.I. I. Pigment red 122 and C.I. I. A surface-treated quinacridone pigment was obtained by repeating the operation described in Example 1 (1) except that the mixture was Pigment Red 209.

(2) Production of pigment dispersion To 15 parts of the surface-treated quinacridone pigment obtained in Comparative Example 1 (1), 2 parts of triethanolamine and 83 parts of ion-exchanged water were added as a neutralizing agent, and a paint shaker (using glass beads; beads) A surface-treated quinacridone pigment dispersion was obtained by dispersing the pigment until the average particle size (secondary particle size) of the pigment reached 95 nm using a filling rate = 60%; media size = 1.7 mm).

(3) Preparation of Ink for Inkjet Recording With respect to 40 parts of the surface-treated quinacridone pigment dispersion obtained in Comparative Example 1 (2), 0.1 part of Surfinol 104, 0.4 part of Surfinol 465, By gradually adding 5 parts of ethylene glycol monobutyl ether, 10 parts of glycerin, 5 parts of triethylene glycol and 44.5 parts of ion-exchanged water while stirring, the ink of Comparative Example 1 according to the present invention (pigment concentration 6%) Got.
The additive composition is shown below.
Pigment dispersion 40 parts Surfinol 465 1 part Glycerin 10 parts Triethylene glycol 5 parts Ion-exchanged water 44 parts

(Comparative Example 2)
(1) Production of surface-treated quinacridone pigment In this comparative example, C.I. I. Only Pigment Red 122 was used.
The pigment to be treated is C.I. I. A surface-treated quinacridone pigment was obtained by repeating the operation described in Example 1 (1) except that only Pigment Red 122 was used.

(2) Production of pigment dispersion To 15 parts of the surface-treated quinacridone pigment obtained in Comparative Example 2 (1), 2 parts of triethanolamine and 83 parts of ion-exchanged water were added as a neutralizing agent. A surface-treated quinacridone pigment dispersion was obtained by dispersing the pigment until the average particle size (secondary particle size) of the pigment became 110 nm using a filling rate = 60%; media size = 1.7 mm).

(3) Preparation of inkjet recording ink For 40 parts of the surface-treated quinacridone pigment dispersion obtained in Comparative Example 2 (2), 1 part of Surfinol 465, 10 parts of glycerin, 5 parts of triethylene glycol, ions By gradually adding 44 parts of exchange water with stirring, an ink of Comparative Example 2 (pigment concentration 6%) according to the present invention was obtained.
The additive composition is shown below.
Pigment dispersion 40 parts Surfinol 465 1 part Glycerin 10 parts Triethylene glycol 5 parts Ion-exchanged water 44 parts

  The following evaluation was performed about the ink composition of Examples 1-3 and Comparative Examples 1-2.

"Storage stability test"
The ink was placed in a glass sample bottle and allowed to stand at 70 ° C. for 1 week, and the generated foreign matter and physical properties (viscosity, average particle diameter, surface tension) before and after being left were examined. The foreign matter was evaluated by observing the amount of the foreign matter remaining on the filter with a microscope after filtering the ink with a 25 μm twill filter, and each physical property value was measured by the above-described apparatus and measurement method.
The evaluation criteria are as follows.
A: Almost no occurrence of foreign matter and no change in physical property value. Good storage stability.
B: Foreign matter is generated or physical property value is changed. In both cases, the change is slight and there is no practical problem.
C: Foreign matter is generated or physical property value is changed. At least one of them is a practically problematic level.

  Next, the ink that was allowed to stand at 70 ° C. for 1 week in the storage stability test was filled into an ink jet recording printer PX-V500 manufactured by Seiko Epson Corporation, and the following printing test was performed.

The recording paper used for printing is Zeloc-P (manufactured by Fuji Xerox) as neutral plain paper, EPP (manufactured by Seiko Epson) as acidic plain paper, and Xerox-R (manufactured by Fuji Xerox) as recycled paper. In addition, after printing, the printer was turned off and the same printing test was conducted after leaving for one week.
The evaluation criteria are as follows.

"Print test"
A: Good print quality for all paper types. There is no problem with the dischargeability after leaving for one week.
B: Print quality is generally good. Although it decreases slightly for some types of paper, it is at a level where there is no practical problem. When printing is performed after being left for one week, there is a discharge failure. However, the discharge performance is restored by repeating the cleaning operation several times.
C: Dot missing or the like occurs in printing, and good printing quality cannot be obtained. If printing is performed after being left for one week, there is a discharge failure and it does not recover even after repeated cleaning operations.

"Water resistance test for recorded materials"
Water droplets were dropped on the printed part of the recorded matter and the state of the printed image (characters and solid printing) after drying was visually confirmed. The state was determined based on the following criteria.
A: No trace of water droplets remains on all recording papers.
B: A trace of water droplets remains on at least a part of the recording paper.
C: A trace of water droplets remains on at least a part of the recording paper.
The above evaluation determination results are summarized in Table 1.

  As is apparent from Table 1, the ink composition of the present invention is excellent in ejection stability and storage stability when used as an ink for an ink jet printer, and high reliability is obtained. In addition, the ink composition of the present invention can provide a recorded matter with good print quality of the recorded image (printed matter) and good water resistance.

Since the water-based ink composition of the present invention ensures excellent storage stability and ejection stability, it is particularly suitable for use as an ink for inkjet recording.

Claims (7)

An aqueous pigment ink comprising at least water, a permeable organic solvent, a humectant, and surface-treated pigment particles that can be dispersed and / or dissolved in water without a dispersant;
The water-based pigment ink, wherein the surface-treated pigment particles are obtained by bonding a hydrophilic dispersion group to particles of a solid solution pigment containing two or more kinds of pigments having different molecular structures in one particle.   The surface-treated pigment particles are obtained by bonding a hydrophilic dispersion group to solid solution pigment particles composed of two or more kinds of organic pigments having different molecular structures in one particle, and the organic pigment in the solid solution pigment particles The aqueous pigment ink according to claim 1, wherein at least one kind has a halogen group on the surface.   The aqueous pigment ink according to claim 2, wherein at least one of the organic pigments having a halogen group in the solid solution pigment particles has no dispersing group bonded thereto.   The penetrating organic solvent is selected from the group consisting of glycol monoether derivatives of polyhydric alcohols, 1,2-alkyldiols, and derivatives having a 1,3-propanediol skeleton. The water-based pigment ink according to any one of the above.   5. The water-based pigment ink according to claim 2, wherein two or more types of organic pigments having different molecular structures have the same basic molecular skeleton.   6. An ink jet recording method for performing recording by discharging droplets of the water-based pigment ink according to any one of claims 1 to 5 and attaching the droplets to a recording medium. A recorded matter obtained by printing the water-based pigment ink according to any one of claims 1 to 5 by an inkjet recording method.