JP2005097433A - Inkjet pigment dispersion ink and ink set - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain ink that has excellent ink discharge stability, forms a recording product having excellent scratch resistance on a recording medium and does not lose gloss in the case of formation of an image on a glossy medium, and to provide an ink set for securing sufficient color development of a recording product. <P>SOLUTION: The pigment dispersion ink for inkjet containing pigment in ink is ink for inkjet containing a resin copolymerized with at least a vinyl-based monomer represented by the formula (R is H, CH<SB>3</SB>, EO=CH<SB>2</SB>CH<SB>2</SB>O or PO=CH<SB>2</SB>CH(CH<SB>3</SB>)O; (l) is an integer of 0-30; (m) is an integer of 1-5; (n) is an integer of 1-20) in ink. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an ink-jet pigment-dispersed ink that is ejected by an ink-jet method and used for image formation, and in particular, a recorded matter on a recording medium formed using the ink has improved scratch resistance and gloss. The present invention relates to an inkjet pigment-dispersed ink and an ink set.

  2. Description of the Related Art Conventionally, inks for ink jet recording have been used having physical properties with high permeability to a recording medium in consideration of the fixing speed and color bleed. As a result, the color material of the ink penetrates into the recording medium, and the amount of the color material to be fixed on the surface cannot be secured sufficiently, making it difficult to obtain a recorded material with good color development. It was. In response to this, for example, various coating layers are provided on the surface of the recording medium to suppress the penetration of the coloring material and to improve the color developability. Further, as a countermeasure from the ink side, a method of increasing the amount of fixing on the surface of the recording medium by using a reaction liquid that reacts with the color material in the ink and precipitating or aggregating the color material to perform solid-liquid separation. There is. Such a method is very effective in that a recording medium is not selected.

  However, in this case, if the fixing amount on the surface of the recording medium is increased in order to improve the color developability, the binding force between the pigment fine particles is weak, and the recorded matter is easily disturbed even when rubbed with a very weak force. There was a problem of poor abrasion resistance. On the other hand, there is a proposal to improve the scratch resistance of the recorded matter on the recording medium by adding a water-soluble resin to the pigment-dispersed ink (for example, see Patent Document 1). However, in the case of a water-soluble resin as described in Patent Document 1, if an amount of resin sufficient to ensure image scratch resistance is added to the ink, the ink ejection stability decreases, and recording on a recording medium is performed. Another problem is that things get confused.

  In particular, in the case of recorded matter on glossy media with glossiness (hereinafter referred to as glossy media), the pigment used does not penetrate into the glossy media because the pigments used are fine particles. There is a problem in that the fine pigment particles form minute irregularities on the surface, and the gloss of the media where the image is formed disappears. In response to this, a proposal has been made in which a pigment and latex are contained in the ink and the relationship between the particle size of the pigment and latex is defined (for example, see Patent Document 2). However, ink containing resin fine particles such as latex has extremely poor ejection stability, and as a result, the landing accuracy of ink droplets on a recording medium is deteriorated, resulting in a problem that the recorded matter is very disturbed.

  Further, the ink is made to contain a surfactant comprising a potassium salt of a C8-C18 alcohol phosphate ester, a phosphorylated ester of isooctanol, and a phosphorylated coester of C8-C18, thereby suppressing a decrease in glossiness. There is a proposal about this (for example, refer to Patent Document 3). However, such a phosphorylated ester causes a decrease in the surface tension of the ink when added in a small amount, and as a result, the ejection stability of the ink decreases. That is, there is a trade-off relationship between the suppression of the decrease in glossiness of the medium and the maintenance of the ejection stability of the ink, and there has been a problem that even if the above-described materials are used, these characteristics cannot be achieved.

  Further, the pigment dispersant contains 3 to 25 mol% of at least one monomer of the following formulas (I), (II) and (III) and 5 to 60 mol% of α, β-ethylenically unsaturated carboxylic acid. There is a proposal about an aqueous pigment ink using a polymer to be used (for example, see Patent Document 4).

（上記式（Ｉ）〜（III）中、Ｒ＝Ｈ又はＣＨ₃、ＥＯ＝ＣＨ₂ＣＨ₂Ｏをそれぞれ表し、ｍ及びｎ＝２〜２４の整数、ｌ＝１〜１２の整数、ｐ＝１〜１２の整数、ｑ＝０〜１６の整数を表す。）

(In the above formulas (I) to (III), R = H or CH ₃ , EO = CH ₂ CH ₂ O, respectively, and m and n = 2 to 24, l = 1 to 12, integers p = (An integer of 1 to 12, q = 0 to 16 represents an integer.)

  However, according to the study by the present inventors, when a polymer obtained by copolymerizing the monomer (III) is used as a dispersant, foaming occurs when the pigment is dispersed, and the pigment is not sufficiently dispersed. Bubbles may be generated in the ink jet nozzle at the time of discharge, causing clogging of the ink jet nozzle.

JP-A-5-263029 JP 2001-106951 A JP 10-176131 A JP-A-6-306317

  The present invention is excellent in ink ejection stability when used as an ink for ink jet recording, a recorded matter formed on a recording medium has excellent scratch resistance, and forms an image on glossy media. The purpose of the present invention is to provide a pigment-dispersed ink (hereinafter referred to as ink) that can form a recorded material that does not lose its glossiness, and an ink set that can ensure sufficient color development of the recorded material on the recording medium. To do.

（上記式中、Ｒ＝Ｈ又はＣＨ₃、ＥＯ＝ＣＨ₂ＣＨ₂Ｏ、ＰＯ＝ＣＨ₂ＣＨ(ＣＨ₃)Ｏをそれぞれ表し、ｌ＝０〜３０の整数、ｍ＝１〜５の整数、ｎ＝１〜２０の整数を表す。） The above object is solved when the following ink jet ink and ink set are used. That is, the present invention is [1] an ink jet ink containing a pigment in the ink, wherein the ink contains a resin obtained by copolymerizing at least a vinyl monomer represented by the following formula: Ink.

(In the formula, it represents R = H or _{CH 3, EO = CH 2 CH} 2 O, PO = CH 2 CH (CH 3) O , respectively, l = 0 to 30 integer, m = 1 to 5 integer, n represents an integer of 1 to 20.)

  Moreover, the following [2]-[4] is mentioned as a preferable form of the inkjet ink concerning this invention. [2] The inkjet ink according to [1], wherein the pigment in the ink is dispersed by a dispersant. [3] The inkjet ink according to [1], wherein the pigment in the ink contains a self-dispersing pigment. [4] The ink-jet ink according to the above [1], wherein the resin functions as a pigment dispersant.

（上記式中、Ｒ＝Ｈ又はＣＨ₃、ＥＯ＝ＣＨ₂ＣＨ₂Ｏ、ＰＯ＝ＣＨ₂ＣＨ(ＣＨ₃)Ｏをそれぞれ表し、ｌ＝０〜３０の整数、ｍ＝１〜５の整数、ｎ＝１〜２０の整数を表す。） Another embodiment of the present invention is represented by the following formula in an ink set independently including an ink in which a pigment is dispersed and a reaction liquid containing a reactive agent that reacts with the ink. An ink set comprising a resin obtained by copolymerizing at least a vinyl monomer in at least one of the ink and the reaction liquid.

(In the formula, it represents R = H or _{CH 3, EO = CH 2 CH} 2 O, PO = CH 2 CH (CH 3) O , respectively, l = 0 to 30 integer, m = 1 to 5 integer, n represents an integer of 1 to 20.)

  As a result of intensive studies on the above-mentioned problems of the prior art, the present inventors have determined that the composition of the ink in the ink for ink jet recording in which the pigment is dispersed is a water solution obtained by copolymerizing at least the specific vinyl monomer. In addition to being excellent in ink ejection stability, which is a basic characteristic of ink-jet inks, it is excellent in scratch resistance of recorded matter formed on a recording medium, and on glossy media. The inventors have found that an ink capable of forming a recorded material that does not lose its glossiness when an image is formed is obtained. Furthermore, if the ink is combined with a reaction liquid that reacts with the ink, and both are used together to form an image, the recorded matter on the recording medium can ensure sufficient color developability, and image formation with better image quality can be achieved. The inventors have found that it is possible to arrive at the present invention.

（上記式中、Ｒ＝Ｈ又はＣＨ₃、ＥＯ＝ＣＨ₂ＣＨ₂Ｏ、ＰＯ＝ＣＨ₂ＣＨ(ＣＨ₃)Ｏをそれぞれ表し、ｌ＝０〜３０の整数、ｍ＝１〜５の整数、ｎ＝１〜２０の整数を表す。） Hereinafter, the present invention will be described in more detail with reference to preferred embodiments. First, the ink according to the present invention will be described. The ink according to the present invention includes a resin obtained by copolymerizing at least a vinyl monomer represented by the following formula.

(In the formula, it represents R = H or _{CH 3, EO = CH 2 CH} 2 O, PO = CH 2 CH (CH 3) O , respectively, l = 0 to 30 integer, m = 1 to 5 integer, n represents an integer of 1 to 20.)

  As the monomer copolymerizable with the vinyl monomer described in the above formula, any monomer can be used as long as it is copolymerizable with the monomer described in the above formula, and specific examples thereof include the following. For example, monomers containing carboxyl groups such as acrylic acid, methacrylic acid, (anhydrous) maleic acid, itaconic acid, fumaric acid, styrene, α-methylstyrene, benzyl acrylate, benzyl methacrylate, vinyl naphthalene, 4-vinyl benzoic acid , Monomers having an aromatic functional group such as vinyl benzoate and N-vinylcarbazole, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, cyclohexyl (meth) acrylate, 2 -(Meth) acrylic acid esters such as hydroxyethyl (meth) acrylate, acrylamide monomers such as (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N- Vinylacetamide N- vinylformamide, and vinyl monomers such as vinyl acetate, their ethylene oxide or propylene oxide modified compound, and the like.

  Furthermore, a vinyl copolymer resin (hereinafter referred to as a copolymer resin) obtained by copolymerization of the monomer described in the general formula is a random copolymer, a graft copolymer, or a block copolymer. It may be a copolymer of the form. The copolymer resin preferably has a weight average molecular weight in the range of 1,000 to 30,000, more preferably in the range of 3,000 to 15,000. The copolymer resin used as a component of the ink in the present invention is desirably a water-soluble resin, and is preferably contained in the range of 0.1 to 5% by mass with respect to the total mass of the ink. As the copolymer resin used in the present invention, different resins may be used depending on the type of pigment to be contained in the ink, if necessary. By making the resin different depending on the type of pigment used, the scratch resistance and gloss of the recorded matter can be further improved.

  A pigment is used as the colorant constituting the ink according to the present invention, but any of inorganic and organic pigments may be used. The pigment is used in a mass ratio of 1 to 20 mass%, preferably 2 to 12 mass%, based on the total mass of the ink.

Examples of the pigment used in the present invention include the following. Specifically, the black pigment includes carbon black, for example, carbon black produced by a furnace method or a channel method, having a DBP oil absorption of 40 to 200 ml / 100 g and a primary particle diameter of 11 to 11. Those having characteristics of 40 mμ (nm), specific surface area by BET method of 50 to 400 m ² / g, volatile content of 0.5 to 10%, pH value of 2 to 9 and the like are preferably used.

  Examples of commercially available products having such characteristics include No. 2300, no. 900, no. 950, MCF88, No. 33, no. 40, no. 45, no. 52, MA7, MA8, no. 2200B (Mitsubishi Chemical), Raven 1255 (Columbia, Colombia), REGAL400R, REGAL330R, REGAL660R, MOGUL L (Made by Cabot), Color Black FWl, Color Black FW285, Color Black FW18, Col Black FW18, Col There are S160, HIBLACK 900, HIBLACK 890, Printex 35, Printex U (manufactured by Degussa) and the like, and any of them can be preferably used.

  Examples of yellow pigments that can be used in the present invention include C.I. I. Pigment Yellow 1, C.I. I. Pigment Yellow 2, C.I. I. Pigment Yellow 3, C.I. I. Pigment Yellow 13, C.I. I. Pigment Yellow 16, C.I. I. Pigment Yellow 74, C.I. I. Pigment Yellow 83, C.I. I. Pigment Yellow 110, C.I. I. Pigment Yellow 128 and the like.

  Examples of magenta pigments include C.I. I. Pigment Red 5, C.I. I. Pigment Red 7, C.I. I. Pigment Red 12, C.I. I. Pigment Red 48 (Ca), C.I. I. Pigment Red 48 (Mn), C.I. I. Pigment Red 57 (Ca), C.I. I. Pigment Red 112, C.I. I. Pigment Red 122 and the like.

  Examples of cyan pigments include C.I. I. Pigment Blue 1, C.I. I. Pigment Blue 2, C.I. I. Pigment Blue 3, C.I. I. Pigment Blue 15: 3, C.I. I. Pigment Blue 15: 4, C.I. I. Pigment Blue 15: 6, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 22, C.I. I. Vat Blue 4, C.I. I. Vat Blue 6 etc. are mentioned. Of course, the present invention is not limited to these. In addition to the above, a newly produced pigment such as a self-dispersing pigment can of course be used.

  The ink according to the present invention is formed by dispersing the above-described pigment in a liquid medium. However, the ink may have a form in which the pigment is dispersed by a dispersant, or the surface of the pigment may be modified. Alternatively, a self-dispersing pigment in which dispersibility is imparted to the pigment itself may be used without using a dispersant or by dispersing in a liquid medium with a small amount of dispersant. The ink according to the present invention in which a pigment is dispersed with a dispersant uses a high-concentration pigment dispersion obtained by dispersing the pigment with a dispersant as described below, and the pigment dispersion is dispersed in a liquid medium. Can be easily obtained.

  Any dispersant can be used as long as it can disperse the pigment in the liquid medium. For example, the following resin dispersants can be used. Examples of the resin dispersant include acrylic resins, polyamide resins, polyester resins, polypeptides, cellulose and modified products thereof, polyvinyl alcohol, and polyolefins. The weight average molecular weight is preferably in the range of 1,000 to 30,000, more preferably in the range of 3,000 to 15,000.

  More preferably, vinyl monomers containing a carboxyl group such as acrylic acid, methacrylic acid, (anhydrous) maleic acid, itaconic acid, fumaric acid, styrene, α-methylstyrene, benzyl acrylate, benzyl methacrylate, vinyl naphthalene, 4 -Vinyl monomers having an aromatic functional group such as vinyl benzoic acid, vinyl benzoate, N-vinyl carbazole, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, (meth ) (Meth) acrylic acid esters such as cyclohexyl acrylate, acrylamide monomers such as (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-vinylacetamide, N-vinylform Bromide, and vinyl monomers such as vinyl acetate, their ethylene oxide or propylene oxide modified compound, etc., and can be used an acrylic resin obtained polymerization or copolymerization to. In order to improve the dispersibility, among the above, those in which a vinyl monomer having an aromatic functional group is contained in the copolymer are preferable. Furthermore, in order to give the reactivity with the reaction liquid described later, it is preferable that the monomer having the carboxyl group is contained in the copolymer.

（上記式中、Ｒ＝Ｈ又はＣＨ₃、ＥＯ＝ＣＨ₂ＣＨ₂Ｏ、ＰＯ＝ＣＨ₂ＣＨ(ＣＨ₃)Ｏをそれぞれ表し、ｌ＝０〜３０の整数、ｍ＝１〜５の整数、ｎ＝１〜２０の整数を表す。） The acrylic copolymer resin obtained by using the vinyl monomer represented by the following formula described above also functions as a pigment dispersion resin, and can also be used as a pigment dispersion resin in the present invention.

(In the formula, it represents R = H or _{CH 3, EO = CH 2 CH} 2 O, PO = CH 2 CH (CH 3) O , respectively, l = 0 to 30 integer, m = 1 to 5 integer, n represents an integer of 1 to 20.)

  Furthermore, these resin dispersants used in the present invention may be any form of copolymer such as a random copolymer, a graft copolymer, and a block copolymer. In addition, it is preferable to contain these resin dispersing agents in the range of 0.1-5 mass% with respect to the total mass of an ink.

  In the case of a pigment dispersion or the like dispersed with an anionic resin dispersant, a pigment dispersion to which an alkali compound is added can be used in order to improve the dispersion stability of the pigment fine particles. Examples of the alkali compound used at this time include hydroxides of alkali metals such as sodium hydroxide, potassium hydroxide, and lithium hydroxide, ammonia, 2-amino-2-methyl-1-propanol, and N, N-dimethylethanol. Examples include amines such as amines.

  When preparing the ink according to the present invention, it is preferable to use a pigment dispersion to which the alkali compound as described above is added, and that the entire ink is adjusted to be neutral or alkaline. In such a case, since repulsive force due to Coulomb force acts between the pigment fine particles in the ink, the dispersion stability of the pigment can be improved, and the ink can be further improved in long-term storage stability. However, in this case, since it may cause corrosion of various members used in the ink jet recording apparatus, it is desirable that the pH range is 7-10.

  The liquid medium constituting the ink according to the present invention is preferably an aqueous liquid medium, but it is particularly preferable to use a mixed solvent of water and a water-soluble organic solvent. As water used at this time, it is preferable to use ion-exchanged water (deionized water) instead of general water containing various ions.

  Examples of the water-soluble organic solvent used by mixing with water include carbon atoms of 1 such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, tert-butyl alcohol, and the like. Alkyl alcohols of -4; amides such as dimethylformamide and dimethylacetamide; ketones or ketoalcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; Ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol Alkylene glycols having 2 to 6 carbon atoms, such as coal; glycerin; ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, triethylene glycol monomethyl (or ethyl) ether, etc. Lower alkyl ethers of monohydric alcohols; N-methyl-2-pyrrolidone, 2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone and the like. Among these many water-soluble organic solvents, it is particularly preferable to use a polyhydric alcohol such as diethylene glycol or a lower alkyl ether of a polyhydric alcohol such as triethylene glycol monomethyl (or ethyl) ether.

  The content of the water-soluble organic solvent as described above in the ink is generally in the range of 3 to 50% by mass, more preferably in the range of 3 to 40% by mass with respect to the total mass of the ink. The water content used is in the range of 10 to 90% by mass, preferably 30 to 80% by mass, based on the total mass of the ink.

  In addition to the above-described components, the ink according to the present invention may include a surfactant, an antifoaming agent, a preservative, a sizing agent, etc. Can be added. As an example of these addition amounts, 0.05-10 mass%, Preferably 0.5-5 mass% is suitable. As examples of the anionic surfactant, any commonly used ones such as a carboxylate salt type, a sulfate ester type, a sulfonate salt type, and a phosphate ester type can be preferably used.

  A method for producing the ink according to the present invention comprising the above components will be described below. In the case of using a pigment dispersion liquid in which a pigment is dispersed with a resin dispersant for preparing a pigment ink, first, a pigment dispersion liquid is prepared as follows. First, a pigment is added to an aqueous medium (dispersion medium) in which at least the resin dispersant as described above and water are mixed, and after mixing and stirring, dispersion is performed using a dispersion means described below, and then If necessary, classification treatment for removing coarse particles such as centrifugation is performed to obtain a desired pigment dispersion. Next, the aqueous liquid medium described above and an appropriately selected additive component as mentioned above are added to this dispersion and stirred to obtain the ink according to the present invention.

  The ink according to the present invention can also use a self-dispersing pigment as a colorant. In this case, a pigment dispersion obtained by using a pigment that is self-dispersible by performing a necessary treatment on the pigment by a known method is used. As the pigment dispersion, a pigment dispersion in which the pigment is dispersed without using a dispersant or by reducing the amount of the dispersant is used. The present invention in which the pigment dispersion is stirred and mixed in an aqueous liquid medium containing at least water, an additive component appropriately selected as necessary is added, the mixture is stirred, and the self-dispersing pigment is used as a colorant. Ink is produced.

  In the case of using a resin dispersant, a base may be added in order to dissolve the resin dispersant well in an aqueous liquid medium. As bases at this time, organic amines such as monoethanolamine, diethanolamine, triethanolamine, aminemethylpropanol and ammonia, or inorganic bases such as potassium hydroxide and sodium hydroxide are preferably used. Moreover, in the preparation method of the ink containing the pigment, it is effective to perform the premixing for 30 minutes or more before stirring the aqueous medium containing the pigment and preparing the pigment dispersion. It is. That is, such a premixing operation is preferable because it improves wettability of the pigment surface and promotes adsorption of the dispersant on the pigment surface.

  When preparing the above-mentioned pigment dispersion, the disperser used for the pigment dispersion treatment may be any disperser that is generally used, and examples thereof include a ball mill, a roll mill, and a sand mill. Among these, a high-speed sand mill is particularly preferable. Examples of such include a super mill, a sand grinder, a bead mill, an agitator mill, a glen mill, a dyno mill, a pearl mill, and a cobol mill (all are trade names).

  In addition, in an inkjet recording method using an ink containing a pigment, a pigment having an optimum particle size distribution is used because of demands such as clogging resistance, but as a method for obtaining a pigment having a desired particle size distribution, a dispersion is used. Reducing the size of the grinding media of the machine, increasing the filling rate of the grinding media, increasing the processing time, slowing the discharge speed, classifying with a filter or centrifuge after grinding, etc. And a combination of these methods.

Next, the ink set according to the present invention will be described. The ink set according to the present invention independently includes the pigment-dispersed ink having the configuration described above and a reaction liquid containing a reactive agent that reacts with the ink. Hereinafter, the reaction solution used in the present invention will be described. The most suitable reactants contained in the reaction solution used in the present invention are polyvalent metal salts. The polyvalent metal salt is composed of a divalent or higher polyvalent metal ion and an anion that binds to the polyvalent metal ion. Specific examples of polyvalent metal ions include divalent metal ions such as Ca ²⁺ , Cu ²⁺ , Ni ²⁺ , Mg ²⁺ and Zn ²⁺ , and trivalent metal ions such as Fe ³⁺ and Al ^3+. Is mentioned. Examples of the anion include Cl ⁻ , NO ₃ ⁻ , SO ₄ ^{2− and the} like. When an image is formed, the total charge concentration of the polyvalent metal ions in the reaction liquid is set so that the aggregated film is formed by instantaneously reacting with the pigment-dispersed ink according to the present invention on the recording medium. It is desirable that the total charge concentration of reverse polarity ions in the ink be twice or more.

  The reaction liquid used in the present invention can be obtained by, for example, dissolving the above-described reactant such as a polyvalent metal salt in an aqueous liquid medium. The aqueous liquid medium is composed of water and a water-soluble organic solvent. Mixed solvents can be used. Examples of water-soluble organic solvents that can be used in this case include amides such as dimethylformamide and dimethylacetamide, ketones such as acetone, ethers such as tetrahydrofuran and dioxane, polyalkylene glycols such as polyethylene glycol and polypropylene glycol, Alkylene glycols such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, diethylene glycol, ethylene glycol methyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl Lower alkyl ethers of polyhydric alcohols such as ether, ethanol, isopropyl alcohol, n-butyl alcohol Call, other monohydric alcohols such as isobutyl alcohol, glycerin, N- methyl-2-pyrrolidone, 1,3-dimethyl - imidazolidinone, triethanolamine, sulfolane, dimethyl monkey Hoki side, and the like.

  Although there is no restriction | limiting in particular about content of the said water-soluble organic solvent in the reaction liquid used by this invention, 5-60 mass% of the reaction liquid total mass, More preferably, 5-40 mass% is a suitable range. is there. Moreover, as water, it is preferable to use ion-exchange water (deionized water) instead of general water containing various ions.

  In addition, the reaction solution used in the present invention may further contain additives such as a viscosity adjuster, a pH adjuster, a preservative, an antioxidant, etc., if necessary. The selection and addition amount of the surfactant functioning as an accelerator needs attention in order to suppress the permeability of the reaction liquid to the recording medium. Furthermore, the reaction liquid used in the present invention is more preferably colorless, but it is preferable that the reaction liquid has a light color that does not change the color tone of each color ink when mixed with ink on a recording medium. Furthermore, as a preferable range of various physical properties of the reaction solution used in the present invention, the viscosity at about 25 ° C. is 1 to 30 cps. What was adjusted so that it might become the range of (mPa * s) is preferable.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In addition, unless otherwise specified, the display of "part" and "%" in a sentence means a mass standard.

（上記式中、ＥＯ＝ＣＨ₂ＣＨ₂Ｏ、ＰＯ＝ＣＨ₂ＣＨ(ＣＨ₃)Ｏを表す。） <Example 1>
(Synthesis of vinyl copolymer A1)
Using 40 parts of methyl methacrylate and 40 parts of methacrylic acid and 20 parts of BLEMMER 75ANEP-600 (trade name, manufactured by NOF Corporation) represented by the following formula, in 500 parts of 2-propanol, the polymerization temperature is 75 ° C. Radical polymerization was performed using azobisisobutyronitrile while dropping over 3 hours under a N ₂ stream.

(In the above formula, EO = CH ₂ CH ₂ O and PO═CH ₂ CH (CH ₃ ) O are represented.)

  After dropping, the temperature was maintained at 75 ° C. for 2 hours, and then the reaction product was developed in 1000 parts of hexane to remove unreacted material by precipitation purification, followed by drying under reduced pressure to obtain a vinyl copolymer A1. The vinyl copolymer A1 had a weight average molecular weight of 10,000.

(Preparation of ink K1)
Inks K1 were prepared by mixing the following components having the vinyl copolymer A1 obtained as described above and the pigment dispersion PK1. The pigment dispersion PK1 uses carbon black FW18 (manufactured by Degussa) as a pigment, and the pigment dispersion using a resin dispersant made of a styrene-acrylic acid copolymer (acid value 200 mgKOH / g, weight average molecular weight 10,000). And obtained by dispersing in an aqueous medium by a known method. The pigment concentration of the pigment dispersion PK1 was 15%.

[Composition of ink K1]
-Pigment dispersion PK1 30 parts-Vinyl copolymer A1 2 parts-Glycerin 5 parts-Diethylene glycol 5 parts-Isopropyl alcohol 5 parts-Acetylenol EH (trade name, manufactured by Kawaken Fine Chemicals) 1 part-Ion-exchanged water 52 parts

(Glossiness evaluation)
The glossiness was evaluated as follows. The ink K1 was packed in an ink cartridge of an inkjet printer BJS600 (manufactured by Canon Inc.), and a 3 cm square pattern was printed on glossy paper professional photo paper PR-101 (manufactured by Canon Inc.) as an evaluation sample. The glossiness at 60 ° of the evaluation sample was measured with a gloss meter VG2000 (manufactured by Nippon Denshoku Industries Co., Ltd.). As a result, the glossiness of the ink K1 was 89.

(Abrasion resistance evaluation)
A sample image printed in the same manner as that used for the glossiness evaluation was attached to a surface plate that was kept flat so that the image was on the surface. Next, an instrument applied with a load of 2 kg on a plate (3 cm square) with a disinfectant gauze was applied to the image surface and mechanically reciprocated 100 times to rub the image surface. Then, the optical reflection density of the image before rubbing and after rubbing was measured, respectively, and from the obtained reflection density before and after the rubbing property test, the dye residual ratio was obtained from the following formula, and the scratch resistance of the formed image was determined. evaluated. As a result, the dye residual ratio of the ink K1 was 100%.

(Evaluation of ejection stability)
Evaluating the ejection stability, ink K1 was filled in an ink cartridge of a commercially available inkjet printer BJS600 (manufactured by Canon Inc.), and alphanumeric characters were printed on 100 sheets of commercially available plain paper super white paper (manufactured by Canon Inc.). The printing disturbance was visually observed and evaluated according to the following criteria. As a result, the evaluation of the ejection stability of the ink K1 was “good”.
A: The characters are not disturbed.
○: The characters are a little disturbed but can be read.
×: Characters are very confused and difficult to read.

<Example 2>
In this example, an ink K2 having the following composition containing a dispersion obtained by using a self-dispersing pigment as the pigment dispersion and the same vinyl copolymer A1 as used in Example 1 was obtained. The pigment dispersion PK2 used in this example is CAB-O-JET200 (manufactured by Cabot Corporation) obtained by dispersing a self-dispersing pigment in an aqueous medium.

[Composition of ink K2]
・ Pigment dispersion PK2 25 parts ・ Vinyl copolymer A1 2 parts ・ Glycerin 5 parts ・ Diethylene glycol 5 parts ・ Isopropyl alcohol 5 parts ・ Acetylenol EH (trade name, manufactured by Kawaken Fine Chemicals) 1 part ・ Ion-exchanged water 57 parts

  The ink K2 obtained in the above example was evaluated in the same manner as in Example 1. As a result, the glossiness was 98, the dye residual ratio was 97%, and the ejection stability was evaluated as ◎.

<Example 3>
In this example, first, a vinyl copolymer A2 obtained as described below was synthesized, and a pigment dispersion PK3 was prepared using the resulting vinyl copolymer A2 as a pigment resin dispersant. Ink K3 was prepared using this.

（上記式中、ＥＯ＝ＣＨ₂ＣＨ₂Ｏ、ＰＯ＝ＣＨ₂ＣＨ(ＣＨ₃)Ｏを表す。） (Synthesis of vinyl copolymer A2)
A vinyl copolymer A2 was synthesized in the same manner as in Example 1 using 40 parts of styrene and 40 parts of methacrylic acid and 20 parts of Bremer 70ANEP-500 (manufactured by NOF Corporation) represented by the following formula. The resulting vinyl copolymer A2 had a weight average molecular weight of 9,600.

(In the above formula, EO = CH ₂ CH ₂ O and PO═CH ₂ CH (CH ₃ ) O are represented.)

(Preparation of pigment dispersion PK3)
The following components including the vinyl copolymer A2 obtained above were mixed and heated to 70 ° C. with a water bath to dissolve the vinyl copolymer A2.
[Composition of pigment dispersion PK3]
・ Vinyl copolymer A2 8 parts ・ Diethylene glycol 10 parts ・ Ion-exchanged water 250 parts ・ Ammonia 1 part

Next, 30 parts of carbon black (MCF88 manufactured by Mitsubishi Chemical) was added to this solution, and after 30 minutes of premixing, dispersion treatment was performed under the following conditions.
・ Disperser: Sand grinder (Igarashi Machine)
・ Crushing media: Zirconia beads (1mm diameter)
・ Filling rate of grinding media: 75% (volume)
・ Crushing time: 3 hours

  Further, centrifugal separation (centrifugal effect 2,100 G, 60 minutes) was performed to remove coarse particles, and a 1% KOH aqueous solution was added so that the solid content concentration was 15% to obtain a pigment dispersion PK3.

(Preparation of ink K3)
The following components including the pigment dispersion PK3 obtained above were mixed, and ink K3 was prepared according to a conventional method. The obtained ink K3 was evaluated by the same method as in Example 1. As a result, the glossiness was 102, the dye residual ratio was 97%, and the ejection stability was evaluated as ◯.

[Composition of ink K3]
・ Pigment dispersion PK3 30 parts ・ Glycerin 5 parts ・ Diethylene glycol 5 parts ・ Isopropyl alcohol 5 parts ・ Acetylenol EH (trade name, manufactured by Kawaken Fine Chemicals) 1 part ・ Ion-exchanged water 54 parts

<Comparative Example 1>
In Comparative Example 1, a case where an ink not containing a vinyl copolymer characterizing the present invention is used will be described. Ink K4 was prepared in the same manner as in Example 1, using each component having the following composition including the pigment dispersion PK1 used in Example 1.
[Composition of ink K4]
・ Pigment dispersion PK1 30 parts ・ Glycerin 5 parts ・ Diethylene glycol 5 parts ・ Isopropyl alcohol 5 parts ・ Acetylenol EH (trade name, manufactured by Kawaken Fine Chemicals) 1 part ・ Ion-exchanged water 54 parts

  The ink K4 obtained above was evaluated for glossiness and scratching by the same method as described in Example 1. As a result, the glossiness of the ink K4 was 30, the dye residual ratio was 60%, and the ejection stability was evaluated as ◯.

<Comparative example 2>
Comparative Example 2 describes the case where an ink containing a water-soluble resin other than the vinyl copolymer characterizing the present invention is used. In this comparative example, polyvinyl alcohol (trade name: Gohsenol NM-14 (manufactured by Nippon Synthetic Chemical Industry Co., Ltd.)) was used as a water-soluble resin, and ink K5 having the following composition was prepared.

(Composition of ink K5)
-Pigment dispersion PK1 30 parts-Gohsenol NM-14 2 parts-Glycerin 5 parts-Diethylene glycol 5 parts-Isopropyl alcohol 5 parts-Acetylenol EH (trade name, manufactured by Kawaken Fine Chemicals) 1 part-Ion-exchanged water 52 parts

  The ink K5 obtained above was evaluated for glossiness and scratch resistance in the same manner as described in Example 1. As a result, the glossiness of the ink K5 was 40, the dye residual ratio was 85%, and the ejection stability was evaluated as x.

Table 1 summarizes the main compositions and evaluation results of the inks of Examples 1 to 3 and Comparative Examples 1 and 2.

<Example 4>
In this example, an ink set is described in which the printing characteristics of a recorded matter on an ink recording medium are improved by using a reaction liquid. In the following manner, three colors of ink, cyan ink C1, magenta ink M1, and yellow ink Y1, and a reaction liquid were prepared. Then, the ink K1 obtained in Example 1 was added thereto to obtain an ink set of this example.

(Preparation of ink C1)
Ink C1 containing pigment was prepared in the same manner as ink K1, except that 30 parts of carbon black (made of carbon black FW18 Degussa) used in preparing ink K1 was replaced with pigment blue 15: 3. did.

(Preparation of ink M1)
Ink M1 containing a pigment was prepared in the same manner as ink K1, except that 30 parts of carbon black (manufactured by Carbon Black FW18 Degussa) used in the preparation of ink K1 was replaced with Pigment Red 122.

(Preparation of ink Y1)
Ink Y1 containing a pigment was prepared in the same manner as ink K1, except that 30 parts of carbon black (carbon black FW18 manufactured by Degussa) used in preparing ink K1 was replaced with pigment yellow 74.

(Preparation of reaction solution S1)
Components of the following composition were mixed to obtain a reaction solution S1.
[Composition of reaction liquid S1]
・ Diethylene glycol 10.0 parts ・ Methyl alcohol 5.0 parts ・ Magnesium nitrate 3.0 parts ・ Acetylenol EH (trade name, manufactured by Kawaken Fine Chemicals) 0.5 part ・ Ion-exchanged water 81.5 parts

  On the PB paper (Canon Co., Ltd.), which is plain paper, using the ink set of the present embodiment consisting of the reaction liquid S1 obtained above and the four colors of ink K1, C1, M1, and Y1. A printed matter 1A was prepared. At this time, after the reaction liquid S1 was applied first, the reaction liquid S1 and the inks K1, C1, M1, and Y1 were applied so that the reaction liquid S1 and each ink were in contact with each other, thereby forming a printed matter 1A. The recording head used here had a recording density of 1,200 dpi, and the driving condition was a driving frequency of 15 kHz. Further, a 4 pl head was used for the ejection volume per dot. The environmental conditions for the printing test were unified to 25 ° C./55% RH.

  When the produced printed matter 1A was observed, bleeding was good and there was no bleeding between colors. Further, as a result of measuring the optical density of each printing portion with a reflection densitometer RD-19I (manufactured by GretagMacbeth), the reflection density is 1.3 for ink K1, 1.2 for ink C1, 1.2 for ink M1, and ink. Y1 was 1.2, indicating high color developability.

  Further, the glossiness and scratch resistance of each of the inks C1, M1, and Y1 were evaluated by the method described in Example 1. The gloss levels of the inks C1, M1, and Y1 were 99, 102, and 96 in this order, and the dye residual ratios were 98, 100, and 98% in the order of C1, M1, and Y1. Moreover, the evaluation of discharge stability was (circle), (double-circle), (circle) in order of C1, M1, and Y1.

Table 2 shows the main composition of the ink set of Example 4 and the evaluation results of each ink constituting the ink set.

As an application example of the present invention, a recorded material having excellent scratch resistance can be formed on a recording medium, and particularly when an image is formed on a glossy medium, the recorded material does not lose its glossiness. It is possible to form an ink-jet ink that can be formed and has excellent ink ejection stability, and is particularly suitable for image formation on glossy media. Furthermore, as another example of use of the present invention, by combining a reaction liquid that reacts with the ink with the above-described excellent image, the recorded matter on the recording medium is sufficient in addition to the effects described above. For example, an ink set for ink-jet recording that can provide a recorded material with excellent image quality that exhibits color developability can be mentioned.

Claims (5)

An ink-jet pigment dispersion ink comprising an ink containing a pigment in the ink and a resin obtained by copolymerizing at least a vinyl monomer represented by the following formula.

(In the formula, it represents R = H or _{CH 3, EO = CH 2 CH} 2 O, PO = CH 2 CH (CH 3) O , respectively, l = 0 to 30 integer, m = 1 to 5 integer, n represents an integer of 1 to 20.) The pigment-dispersed ink for inkjet according to claim 1, wherein the pigment in the ink is dispersed by a dispersant. The pigment-dispersed ink for inkjet according to claim 1, wherein the pigment in the ink contains a self-dispersing pigment. The ink-jet pigment dispersion ink according to claim 1, wherein the resin functions as a pigment dispersant. In an ink set comprising independently a pigment-dispersed ink in which a pigment is dispersed and a reaction liquid containing a reactive agent that reacts with the pigment-dispersed ink, at least a vinyl monomer represented by the following formula: An ink set comprising a copolymerized resin in at least one of the pigment-dispersed ink and the reaction liquid.

(In the formula, it represents R = H or _{CH 3, EO = CH 2 CH} 2 O, PO = CH 2 CH (CH 3) O , respectively, l = 0 to 30 integer, m = 1 to 5 integer, n represents an integer of 1 to 20.)