Colored resin particle dispersion for inkjet and aqueous ink composition for inkjet

Abstract

This invention provides a colored resin particle dispersion and an aqueous ink composition suitable for inkjet applications. [Solution] The inkjet colored resin particle dispersion of the present invention is characterized in that colored resin particles, each composed of at least a (meth)acrylic acid ester monomer represented by the following general formula (X) and at least one dye selected from the following group A, are dispersed in water. TIFF2026074680000007.tif33145 [In the formula, A is a hydrogen atom (H) or a methyl group (CH3), and R is a hydrogen atom (H), an alkyl group having 1 to 22 carbon atoms, etc.] Group A: Basic dyes, oil-soluble dyes, acid dyes, and salt-forming dyes which are salt-forming products of basic dyes. The present invention is characterized by comprising an inkjet-compatible aqueous ink composition comprising a dispersion of colored resin particles for inkjet use having the above-described configuration.

Description

Technical Field

[0001] The present invention relates to a colored resin particle dispersion for inkjet and an aqueous ink composition for inkjet.

Background Art

[0002] Conventionally, as colorants for inkjet, those mainly composed of pigments such as carbon black, those in which dyes are dissolved, and those using colored resin particles are known. Colored resin particles improve water resistance, color development properties, etc. while taking advantage of the characteristics of the colorant regarding image formation by enclosing the colorant in resin to form colored resin particles. Here, as the resin, it is desired to have properties that impart water resistance, light resistance, stability over time, and color development properties to the ink.

[0003] Conventional colored resin particle dispersions for inkjet and aqueous ink compositions for inkjet include, for example, 1) having colored resin particles and water as a dispersion medium for dispersing the colored resin particles, wherein the colored resin particles are produced by combining the dispersion medium in an emulsion in which a dispersion medium containing a resin, a colorant, and an organic solvent is dispersed in an aqueous dispersion medium, and the acid value of the resin is 15 KOHmg / g or more and 100 KOHmg / g or less, an ink for inkjet (see, for example, Patent Document 1), 2) a colored resin particle dispersion containing colored resin particles, a basic dispersant, and a non-aqueous solvent, the colored resin particles containing a colorant and a (meth)acrylic resin, the (meth)acrylic resin having a unit A having a carboxy group, a unit B having a phosphoric acid group and / or a phosphoric acid ester group, and a unit C having an aromatic ring, an inkjet ink containing this colored resin particle dispersion (see, for example, Patent Document 2),

[0004] 3) A colored resin particle dispersion comprising colored resin particles and water, wherein the colored resin particles comprise at least one dye selected from the group consisting of oil-soluble dyes, disperse dyes, and vat dyes, and a water-insoluble chain polymer, the water-insoluble chain polymer having a structure represented by a specific formula, a cyclic structure, and hydrophilic groups, is known as a colored resin particle dispersion, an ink for inkjet use containing this colored resin particle dispersion (see, for example, Patent Document 3).

[0005] However, while the colored resin particle dispersions and aqueous ink compositions for inkjet printers described in Patent Documents 1 to 3 above exhibit better color tones and color density than conventional materials, resulting in good color development, it is still difficult to achieve a high level of balance between water resistance, light resistance, long-term stability, and color development, and they have not been satisfactory. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2013-91718 (Claims, Examples, etc.) [Patent Document 2] Japanese Patent Publication No. 2018-53069 (Claims, Examples, etc.) [Patent Document 3] Japanese Patent Publication No. 2014-132061 (Claims, Examples, etc.) [Disclosure of the Invention] [Problems that the invention aims to solve]

[0007] In view of the problems of the prior art described above, the present invention aims to solve these problems and provides an inkjet-compatible colored resin particle dispersion and an inkjet-compatible aqueous ink composition that achieve a high degree of balance between water resistance, light resistance, long-term stability, and color development, thereby exhibiting excellent performance. [Means for solving the problem]

[0008] In view of the above-mentioned conventional problems, the inventors conducted diligent research and found that, by using a colored resin particle dispersion composed of at least a (meth)acrylic acid ester monomer represented by a specific formula and a specific dye, the above-mentioned colored resin particle dispersion and inkjet aqueous ink composition can be obtained, thus completing the present invention.

[0009] In other words, the inkjet-compatible colored resin particle dispersion of the present invention is characterized in that colored resin particles, each composed of at least a (meth)acrylic acid ester monomer represented by the following general formula (X) and at least one dye selected from the following group A, are dispersed in water. [ka] [In the above formula (X), A is a hydrogen atom (H) or a methyl group (CH3), and R represents a substituent having a hydrogen atom (H), an alkyl group having 1 to 22 carbon atoms, or a polyalkylene glycol chain having 2 to 18 carbon atoms. The substituent having an alkyl group or a polyalkylene glycol chain may have a phenyl group, a benzyl group, an epoxy group, a hydroxyl group, a dialkylamino group, an alkoxy group having 1 to 18 carbon atoms, a perfluoroalkyl group having 1 to 18 carbon atoms, or a trialkoxysilyl group as a substituent.] Group A: Basic dyes, oil-soluble dyes, acid dyes, and salt-forming dyes which are salt-forming products of basic dyes. Preferably, the colored resin particles further contain terpene phenol resin. It is preferable that the average particle size of the colored resin particles is 10 to 800 nm. The present invention is characterized by comprising an inkjet-compatible aqueous ink composition comprising a dispersion of colored resin particles for inkjet use having the above-described configuration. [Effects of the Invention]

[0010] According to the present invention, a colored resin particle dispersion for inkjet applications and an aqueous ink composition for inkjet applications are provided that achieve a high degree of balance between water resistance, light resistance, long-term stability, and color development, and exhibit excellent performance. The object and effect of the present invention are recognized and obtained, in particular, by using the components and combinations indicated in the claims. Both the general description above and the detailed description below are illustrative and descriptive, and do not limit the present invention as described in the claims. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described in detail below. However, it should be noted that the technical scope of the present invention is not limited to each of the embodiments described below, but extends to the invention described in the claims and its equivalents. The inkjet-compatible colored resin particle dispersion of the present invention is characterized in that colored resin particles, each composed of at least a (meth)acrylic acid ester monomer represented by the following general formula (X) and at least one dye selected from the following group A, are dispersed in water. [ka] [In the above formula (X), A is a hydrogen atom (H) or a methyl group (CH3), and R represents a substituent having a hydrogen atom (H), an alkyl group having 1 to 22 carbon atoms, or a polyalkylene glycol chain having 2 to 18 carbon atoms. The substituent having an alkyl group or a polyalkylene glycol chain may have a phenyl group, a benzyl group, an epoxy group, a hydroxyl group, a dialkylamino group, an alkoxy group having 1 to 18 carbon atoms, a perfluoroalkyl group having 1 to 18 carbon atoms, or a trialkoxysilyl group as a substituent.] Group A: Basic dyes, oil-soluble dyes, acid dyes, and salt-forming dyes which are salt-forming products of basic dyes.

[0012] The (meth)acrylic acid ester monomer represented by the general formula (I) used in the present invention is chosen because it can produce stable particles with consistent concentrations of the above-mentioned dyes of group A that can be encapsulated, does not adversely affect other components, and has a long-lasting effect. In the above general formula (I), R represents a hydrogen atom (H), a C1-C22 alkyl group, or a substituent having a polyalkylene glycol chain with 2-C18 carbon atoms. The substituent having an alkyl group or polyalkylene glycol chain may have a phenyl group, benzyl group, epoxy group, hydroxyl group, dialkylamino group, C1-C18 alkoxy group, C1-C18 perfluoroalkyl group, or trialkoxysilyl group as a substituent. Examples include linear or branched alkyl groups having C1-C20 carbon atoms, cycloalkyl groups having C3-C10 carbon atoms, and alkyl groups having C1-C18 carbon atoms, which may have an epoxy group, hydroxyl group, dialkylamino group, or C1-C4 alkoxy group as a substituent. In particular, examples include alkyl groups having C1-C6 carbon atoms, which may have an epoxy group, hydroxyl group, or C1-C2 alkoxy group as a substituent, and alkyl groups having C1-C6 carbon atoms, which may have an epoxy group as a substituent. Preferably, R in the above general formula (I) is a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, a hydroxyl group, a trifluoroethyl group, a dimethylaminoethyl group, a methoxyethyl group, a hydroxyethyl group, a hydroxypropyl group, an allyl group, a tetrahydrofurfuryl group, a phenyl group, a benzyl group, a butoxydiethylene glycol group, a methoxypolyethylene glycol group, a dimethylaminoethyl group, a diethylaminoethyl group, a dimethylaminoethyl group, a glycidyl group, ethyl phosphate, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, etc. In this specification, the term "(meth)acrylic acid" refers to "acrylic acid and / or methacrylic acid."

[0013] Specific examples of (meth)acrylic acid esters represented by the above general formula (I) include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, palmityl (meth)acrylate, stearyl (meth)acrylate, behenyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, Isobornyl (meth)acrylate, glycidyl (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, allyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, dimethylaminoethyl methyl chloride (meth)acrylate, diethylaminoethyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,6 - hexanediol, trimethylolpropane tri(meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, trifluoroethyl (meth)acrylate, butoxyethyl (meth)acrylate, methoxytetraethylene glycol (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-chloro-2-hydroxypropyl (meth)acrylate, 2-hydroxy-3-phenoxypropyl (meth)acrylate, diethylene glycol (meth)acrylate, 2-(dimethylamino)ethyl (meth)acrylate, 2-(dimethylamino)propyl (meth)acrylate, 2-(dimethylamino)butyl (meth)acrylate, 2-isocyanoethyl (meth)acrylate, 2-(acetoacetoxy)ethyl (meth)acrylate, perfluoroethyl methacrylate having a perfluoroalkyl having 1 to 18 carbon atoms, 2-(phosphate)ethyl (meth)acrylate [2-(Methacryloyloxy)ethyl phosphate], trialkoxysilylpropyl (meth)acrylate, dialkoxymethylsilylpropyl (meth)acrylate, etc. of at least one kind (each alone or two or more kinds, the same applies hereinafter) may be mentioned., Among these, from the viewpoints of being industrially easily available, being easy and safe to handle during production, and further improving the effects of the present invention, preferably, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate are desirable.,

[0014] In the present invention, in addition to the above (meth)acrylate monomer, furthermore, for the purpose of obtaining effects such as having a persistent color tone, color density at the time of color development, excellent discoloration sensitivity, dispersion stability, and light resistance, preferably, hydrophobic vinyl monomers and aqueous monomers other than the above (meth)acrylate monomers can be used., 'As the hydrophobic vinyl monomer, for example, at least one monomer such as styrenes such as styrene and methylstyrene other than the above (meth) acrylic acid ester monomer can be used. Examples of the hydrophobic vinyl monomer that can be used include, for example, at least one of styrene, methylstyrene, chloromethylstyrene, alkylstyrene having an alkyl group with 1 to 12 carbon atoms, methoxystyrene, chlorostyrene, bromostyrene, divinylbenzene, phenylstyrene, vinylnaphthalene, etc. Examples of the aqueous monomer that can be used include, for example, at least one of glycerin monomethacrylate, sodium 2-sulfoethyl methacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monomethacrylate, polyethylene glycol-propylene glycol monomethacrylate, polyethylene glycol-tetramethylene glycol-monomethacrylate, propylene glycol-polybutylene glycol-monomethacrylate, etc.

[0015] Examples of the dye used in the present invention include at least one dye selected from the basic dyes, oil-soluble dyes, acidic dyes in Group A above, and salt-forming dyes which are salt-forming bodies of acidic dyes and basic dyes. In the present invention, the limitation to the basic dyes, oil-soluble dyes, and salt-forming dyes in Group A above is because they have water resistance and good compatibility with the (meth) acrylic acid ester represented by the general formula (I). Examples of the basic dye that can be used in the present invention include, for example, at least one of basic dyes such as di- and triarylmethane dyes; quinoneimine dyes such as azine (including nigrosine), oxazine, thiazine, etc.; xanthene dyes; triazole azo dyes; thiazole azo dyes; benzothiazole azo dyes; azo dyes; methine dyes such as polymethine, azomethine, azamethine, etc.; anthraquinone dyes; phthalocyanine dyes, etc., and preferably, water-soluble basic dyes are desirable. Specific examples of yellow basic dyes that can be used include the dyes listed in the COLOR INDEX, such as CI Basic Yellow-1, -2, -9, -11, -12, -13, -14, -15, -19, -21, -23, -24, -25, -28, -29, -32, -33, -34, -35, -36, -40, -41, -51, -63, -73, and -80. Commercially available yellow basic dyes include AIZEN CATHILON YELLOW GPLH (a product name manufactured by Hodogaya Chemical Co., Ltd.). Examples of orange basic dyes include those listed in the COLOR INDEX, such as CI Basic Orange-1, -2, -7, -14, -15, -21, -22, -23, -24, -25, -30, -32, -33, and -34. Examples of basic red dyes include those listed in the COLOR INDEX, such as CI Basic Red-1, -2, -3, -4, -8, -9, -12, -13, -14, -15, -16, -17, -18, -22, -23, -24, -25, -26, -27, -29, -30, -32, -34, -35, -36, -37, -38, -39, -40, -41, -42, -43, -46, -49, -50, -51, -52, and -53. Other commercially available red basic dyes include AIZEN CATHILON RED BLH, AIZEN CATHILON RED RH (product names from Hodogaya Chemical Co., Ltd.), Diacryl Supra Brilliant Red 2G (product name from Mitsubishi Chemical Corporation), and Sumiacryl Red B (product name from Sumitomo Chemical Co., Ltd.).

[0016] Examples of purple basic dyes include those listed in the COLOR INDEX, such as CI Basic Violet-1, -2, -3, -4, -5, -6, -7, -8, -10, -11, -11:1, -12, -13, -14, -15, -16, -18, -21, -23, -24, -25, -26, -27, -28, -29, -33, and -39. Examples of basic blue dyes include those listed in the COLOR INDEX, such as CI Basic Blue-1, -2, -3, -5, -6, -7, -8, -9, -15, -18, -19, -20, -21, -22, -24, -25, -26, -28, -29, -33, -35, -37, -40, -41, -42, -44, -45, -46, -47, -49, -50, -53, -54, -58, -59, -60, -62, -63, -64, -65, -66, -67, -68, -69, -70, -71, -75, -77, -78, -79, -82, -83, -87, -88, etc. Other commercially available blue basic dyes include AIZEN CATHILON TURQUOISE BLUE LH (product name manufactured by Hodogaya Chemical Co., Ltd.). Examples of basic green dyes include those listed in the COLOR INDEX, such as CI Basic Green-1, -4, -6, and -10. Commercially available basic green dyes include Diacryl Supra Brilliant Green 2GL (a product name from Mitsubishi Chemical Corporation). Examples of brown basic dyes include those listed in the COLOR INDEX of CI Basic Brown-1, -2, -4, -5, -7, -11, -12, -13, and -15. Commercially available brown basic dyes include Janus Brown R (a product name from Nippon Chemical Co., Ltd.) and AIZEN CATHILON BROWN GH (a product name from Hodogaya Chemical Co., Ltd.). Examples of black basic dyes include the dyes listed in the COLOR INDEX, such as CI Basic Black-1, -2, -3, -7, and -8, or nigrosine-based basic dyes.

[0017] Examples of oil-soluble dyes used in this invention include commercially available monoazos, disazos, metal complex salt monoazos, anthraquinones, phthalocyanines, and triarylmethanes. Salt-forming type oil-soluble dyes, in which functional groups such as acidic and basic dyes are substituted with hydrophobic groups, can also be used. Examples of yellow shades include CI Solvent Yellow 114 and 116; orange shades include CI Solvent Orange 67; red shades include CI Solvent Red 122 and 146; blue shades include CI Solvent Blue 5, 36, 44, 63, 70, 83, 105, and 111; and black shades include CI Solvent Black 3, 7, 27, and 29. Specific commercially available oil-soluble dyes that can be used include the blue dye SBN Blue 701 (manufactured by Hodogaya Chemical Co., Ltd.), the blue dye Oil Blue 650 (manufactured by Orient Chemical Co., Ltd.), the red dye SOC-1-0100 (manufactured by Orient Chemical Co., Ltd.), and Oil Black 860 (manufactured by Orient Chemical Co., Ltd.).

[0018] The salt-forming dye used in this invention, which is a salt-forming compound of an acid dye and a basic dye, is a compound obtained by reacting an acid dye and a basic dye. Without reducing the characteristics of the highly color-developing acid dye, which is the raw material, both the acid dye and the basic dye have excellent spectral characteristics and color purity. Furthermore, it has the advantage that the spectral properties of the salt-forming compound can be adjusted by combining the acid dye and the basic dye. Furthermore, in the present invention, the salt product of an acid dye and a basic dye differs from inorganic salts of acid dyes having acidic groups such as sulfonic acid and carboxylic acid, which are derivatives of acid dyes; salts of acid dyes and nitrogen-containing compounds; and amide compounds such as sulfonamides of acid dyes. Instead, it is a compound obtained by a chemical (salt formation) reaction between an acid dye whose dye ions are anionic and a basic dye whose dye ions are cationic. Therefore, it has an extremely rigid structure and is chemically stable.

[0019] Therefore, when a salt-forming dye, which consists of a salt-forming compound of an acid dye and a basic dye, is used as a coloring agent for colored resin particles, it functions as a chemically stable compound, unlike when a mixture of dyes is used. As a result, the excellent spectral properties and color purity of each of the acid dyes and basic dyes are not impaired, and colored resin particles with excellent color development and brightness are obtained. Furthermore, due to its structural stability, it exhibits excellent spectral properties with superior heat and light resistance. In addition, without reducing the properties of the highly colored acid dyes used as starting materials in the salt formation reaction, the acid dyes and basic dyes each possess excellent spectral properties and color purity, allowing for arbitrary spectral adjustment by changing the combination of starting materials in the salt formation reaction. Moreover, the formation of salt compounds imparts water resistance and other properties, resulting in excellent dispersibility in solvents containing water.

[0020] The basic dyes that can be used include at least one of the basic dyes mentioned above, such as di and triarylmethane dyes; quinone imine dyes such as azine (including nigrosine), oxazine, and thiazine dyes; xanthene dyes; triazole azo dyes; thiazole azo dyes; benzothiazole azo dyes; azo dyes; methine dyes such as polymethine, azomethine, and azamethine; anthraquinone dyes; and phthalocyanine dyes. Preferably, water-soluble basic dyes are preferred. Examples of specific basic dyes that can be used are the basic dyes of each color mentioned above, which can be selected and used.

[0021] The acidic dyes that can be used are water-soluble dyes that have an acidic group such as a sulfonic acid group or carboxyl group, or a salt thereof, in the structure of the dye molecule. Some acid dyes are classified as direct dyes. Direct dyes have a large molecular weight and a planar structure, and the salt compounds formed by combining direct dyes and basic dyes have particularly excellent heat resistance. By appropriately selecting the monomer species of the resin particles used in the colored resin particles, excellent color development and heat resistance can be achieved.

[0022] Examples of direct dyes that can be used include azo dyes, thiazole dyes, anthraquinone dyes, oxazine dyes, and phthalocyanine dyes. The following are examples of usable dyes, indicated by their color index (CI) numbers. Examples of azo dyes include CI Direct Yellow 2, 33, 34, 35, 39, 50, 69, 70, 71, 86, 93, 94, 95, 98, 102, 109, 129, 136, 141; CI Direct Orange 41,46,56,61,64,70,96,97,106,107; CI Direct Red 79,82,83,84,97,98,99,106,107,172,173,176,177,179,181,182,204,207,211,213,218,221,222,232,233,243,246,250; CIDirect Violet 47,52,54,60,65,66,79,80,81,82,84,89,90,93,95,96,103,104; CI Direct Blue 51,57,71,81,84,85,90,93,94,95,98,100,101,113,149,150,153,160,162,163,164,166,167,170,172,188,192,193,194,196,198 ,200,207,209,210,212,213,214,222,228,229,237,238,242,243,244,245,247,248,250,251,252,256,257,259,260,268,274,275; Examples include CI Direct Green 27, 34, 37, 65, 67, 68, 69, 72, 77, 79, and 82. Among thiazole dyes, CI Direct Yellow 54 is an example.

[0023] Examples of oxazine-based dyes include CI Direct Blue 97, 99, 106, 107, 108, 109, 190, and 293. An example of anthraquinone-based dye is CI Direct Blue 77. Examples of phthalocyanine-based dyes include CIDirect Blue 86, 87, 189, and 199. Other direct dyes include CI Direct Yellow 38, 43, 47, 58, 68, 108, 138; CI Direct Orange 34, 39, 50, 52, 57, 65, 68; CI Direct Red 91, 92, 96, 105, 184, 220, 234, 241; CI Direct Violet 59; CI Direct Blue 80, 114, 115, 117, 119, 137, 155, 156, 158, 159, 161, 171, 173; and CI Direct Green 25, 31, 32, 63, 66.

[0024] In addition to direct dyes, acid dyes that can be used include azo dyes, xanthene dyes, phthalocyanine dyes, anthraquinone dyes, quinoline dyes, azine dyes, and indigoid dyes. Examples of azo dyes include CI Acid Red 1, 3, 4, 6, 8, 11, 12, 14, 18, 26, 27, 33, 37, 53, 57, 88, 106, 108, 111, 114, 131, 137, 138, 151, 154, 158, 159, 173, 184, 186, 215, 257, 266, 296, and 337; CI Acid Orange 7, 10, 12, 19, 20, 22, 28, 30, 52, 56, 74, 127; CI Acid Violet 11, 56, 58; CI Acid Yellow 1, 6, 6C, 17, 18, 23, 25, 36, 38, 42, 44, 54, 59, 72, 78, 151; CI Acid Brown 2, 4, 13, 248; Examples include CI Acid Blue 92, 102, 113, and 117.

[0025] Examples of xanthene dyes include CI Acid Red 50, 51, 52, and 87. An example of a phthalocyanine-based dye is CI Acid Blue 249. Examples of anthraquinone dyes include CI Acid Red 82, 92; CI Acid Violet 41, 42, 43; CI Acid Blue 14, 22, 25, 40, 45, 78, 80, 127, 1, 129, 145, 167, 230; and CI Acid Green 25, 27. An example of a quinoline-based dye is CI Acid Yellow 3. Examples of azine-based dyes include CI Acid Blue 59,102. An example of an indigoid dye is CI Acid Blue 74. Other dyes include CI Acid Violet 49; CI Acid Brown 19; CI Acid Blue 7, 9, 74, 112, 126, 167; and CI Acid Green 9.

[0026] In the present invention, a well-known method can be applied as a method for producing a salt-forming dye, which is a salt-forming body of an acid dye and a basic dye. For example, an aqueous solution of an acid dye and an aqueous solution of a basic dye can be prepared, mixed and stirred, the salt-forming body can be filtered, and the recovered precipitate can be dried to obtain a predetermined salt-forming dye. Furthermore, when manufacturing colored resin particles, it is possible to continuously produce salt bodies and synthesize colored resin particles by mixing acidic dyes and basic dyes.

[0027] In the present invention, a salt-forming dye consisting of a salt-forming compound of a direct dye and a basic dye can be used alone, or a salt-forming dye consisting of two or more salt-forming compounds can be used in combination. Furthermore, in the present invention, commercially available salt-forming dyes, which are salt-forming products of acid dyes and basic dyes, can be used, and salt-forming dyes synthesized using commercially available acid dyes and basic dyes can also be used. Commercially available products include VALIFAST RED 1308 (a salt-formulated product of CI Acid Yellow 23 and CI Basic Red 1) from Orient Chemical Industries, Ltd., VALIFAST RED 1320 (a salt-formulated product of CI Acid Yellow 42 and CI Basic Red 1), VALIFAST RED 1355, VALIFAST RED 1388 (both salt-formulated products of CI Acid Yellow 23 and CI Basic Red 1), VALIFAST GREEN 1501 (a salt-formulated product of CI Acid Yellow 42 and CI Basic Blue 1), VALIFAST VIOLET 1701 (a salt-formulated product of CI Acid Yellow 42 and CI Basic Violet 1), VALIFAST VIOLET 1704 (a salt-formulated product of CI Acid Yellow 36 and CI Basic Violet 1), and salt-formulated dyes synthesized from commercially available products [Water Yellow 6C (manufactured by Orient Chemical Industries, Ltd.: CI Acid Yellow 6C) and Spillon Yellow]. Examples include salt-forming dyes using C-GNH-new (manufactured by Hodogaya Chemical Co., Ltd., a basic dye), salt-forming dyes using CI Acid Blue 9 and Spillon Yellow C-GNH-new (manufactured by Hodogaya Chemical Co., Ltd.), and salt-forming dyes using CI Acid Blue 9 and CI Basic Violet 1.

[0028] The inkjet-compatible colored resin particle dispersion of the present invention comprises at least a (meth)acrylic acid ester monomer represented by the above general formula (X), and at least one dye selected from the basic dyes, oil-soluble dyes, acid dyes, and salt-forming dyes which are salt-forming products of basic dyes of the above-mentioned group A. Furthermore, it is desirable to include a terpene phenol resin in order to further exhibit the effects of the present invention. The terpene phenol resins that can be used are resins obtained by reacting (copolymerizing) cyclic terpene monomers and phenols in the presence of a catalyst, such as a Friedelcraft catalyst. The reaction method is not particularly limited, and various terpene phenol resins can be used, for example, those represented by the following formula (I). [ka] [In equation (I) above, m and n are positive numbers.]

[0029] The terpene monomer used as a raw material for the terpene phenol resin may be a monocyclic terpene monomer or a dicyclic terpene monomer. Specific examples of cyclic terpene monomers used as raw materials include limonene, dipentene (an optical isomer of limonene), terpinolene, α-pinene, β-pinene, terpinene, and mentadiene. Examples of phenols used as raw materials for terpene phenol resins include phenol, cresol, xylenol, propylphenol, hydroquinone, resorcinol, methoxyphenol, bromophenol, bisphenol A, and bisphenol F.

[0030] The terpene phenol resin used can be produced, for example, by reacting 1 mole of terpene monomer and 0.1 to 50 moles of phenols in a cationic polymerization reaction under a catalyst such as a Friedel-Crafts catalyst at a temperature of -10 to 120°C for 0.5 to 20 hours. While a reaction solvent is not strictly necessary, solvents such as aromatic hydrocarbons, alcohols, and ethers are typically used. The terpene phenol resins produced in this manner have different mass-average molecular weights (Mw), softening points, etc., depending on the type and amount of cyclic terpene monomers and phenols used. Alternatively, these terpene phenol resins may be hydrogenated terpene phenol resins to which hydrogen has been added. Preferably, in order to further exhibit the effects of the present invention, the one represented by formula (I) above is desirable.

[0031] Examples of usable terpene phenol resins include those produced by the above manufacturing method, as well as commercially available products from Yasuhara Chemical Co., Ltd. such as YS Polystar T145, YS Polystar T130, YS Polystar K125, YS Polystar S145, YS Polystar N125, and Mighty Ace G150. Examples of hydrogenated terpene phenol resins include commercially available products from Yasuhara Chemical Co., Ltd. such as YS Polystar UH. These can be used individually or in mixtures of two or more.

[0032] The inkjet-compatible colored resin particle dispersion of the present invention comprises, at least, a (meth)acrylic acid ester monomer represented by the above general formula (X), and at least one dye selected from the basic dyes, oil-soluble dyes, acid dyes, and salt-forming dyes which are salt-forming products of basic dyes of group A described above, as well as colored resin particles further containing terpene phenol resin. As a method for producing each of these, for example, at least one dye selected from the above group A described above is dissolved in the above (meth)acrylic acid ester monomer (each individually or in pairs or more, the same applies hereinafter), or in a mixed monomer containing the above (meth)acrylic acid ester monomer and other hydrophobic vinyl monomers and / or aqueous monomers, or a terpene phenol resin is dissolved together with the above dye, and ammonium persulfate, potassium persulfate, hydrogen peroxide, etc. are used as polymerization initiators, and a reducing agent is further used as a polymerization initiator, and triallyl isocyanurate, triallyl isocyanurate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, pentaerythritol acrylate, ditrimethylolpropane acrylate Crosslinking agents such as dipentaerythritol acrylate, methoxylated bisphenol A methacrylate, pentaerythritol methacrylate, ditrimethylolpropane methacrylate, dipentaerythritol methacrylate, ethoxylated polyglycerin methacrylate, and cyclohexyl methacrylate, and, if necessary, polyoxyethylene-1-(allyloxymethyl)-alkyl ether sulfate ammonium, ether sulfate, polyoxyethylene nonylpropenylphenyl ether sulfate ammonium, polyoxyethylene nonylpropenylphenyl ether, ammonium polyacrylate, styrene-maleate copolymer ammonium, polyoxyethylene alkyl ether, polyoxyethylene styrene phenyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyalkylene decyl ether, polyoxyethylene tridecyl ether, alkylbenzene sulfonate, dioctyl sulfosuccinate, sodium lauryl sulfate, polyoxyethylene alkyl ether phosphate, polyoxyethylene styrene phenyl ether phosphate,It can be manufactured by emulsion polymerization using polymerizable surfactants (emulsifiers) such as polyoxyethylene styrene-phenyl ether sulfate, polyoxyethylene alkyl ether sulfate, polyoxyethylene sorbitan monolaurate (Polysorbate 20), polyoxyethylene sorbitan palmitate (Polysorbate 40), polyoxyethylene sorbitan monostearate (Polysorbate 60), and polyoxyethylene sorbitan oleate (Polysorbate 80). After being manufactured as an aqueous dispersion of inkjet-compatible colored resin particles, it can be dried to obtain inkjet-compatible colored resin particles. Using the above-mentioned crosslinking agent is preferable because it improves the heat resistance, mechanical properties, hydrolysis resistance, and weather resistance of the inkjet-grade colored resin particles.

[0033] In the present invention, during the emulsion polymerization described above, an appropriate amount of dicyclopenta(thenyl(meth)acrylate monomer may be further mixed with the (meth)acrylic acid ester monomer before emulsion polymerization. When dicyclopenta(thenyl(meth)acrylate monomer is further mixed and emulsion polymerization is performed, the stability is less likely to be impaired even if the water in the dispersion evaporates, resulting in a dispersion of inkjet-compatible colored resin particles and inkjet-compatible colored resin particles with even greater stability. The dicyclopentanyl(meth)acrylate monomers that can be used include dicyclopentanyl acrylate monomer, dicyclopentenyl acrylate, dicyclopentanyl methacrylate monomer, and dicyclopentenyl methacrylate. Furthermore, in the present invention, when performing the emulsion polymerization described above, in addition to the dicyclopenta(thenyl)acrylate monomer, other (meth)acrylic acid ester monomers, monomers having reactive crosslinking groups such as epoxy groups, hydroxymethylamide groups, and isocyanate groups, or polyfunctional monomers having two or more vinyl groups may be appropriately blended and crosslinked.

[0034] In the present invention, the content of the (meth)acrylic acid ester monomer in the polymer components constituting the inkjet-colored resin particle dispersion is preferably 30% by mass or more, more preferably 30 to 95% by mass, and particularly preferably 30 to 70% by mass, relative to the total polymer components constituting the inkjet-colored resin particle dispersion. In this invention, "total polymer components" refers to the polymerizable components that constitute the inkjet-compatible colored resin particle dispersion, and specifically refers to the total amount of the (meth)acrylic acid ester monomer used, the other monomer components used, and the crosslinking agent described later. By setting the content of the above-mentioned (meth)acrylic acid ester monomer to 30% by mass or more relative to the total polymer components, the effects of the present invention can be suitably exhibited. On the other hand, if the content is less than 30% by mass, the stability over time will be poor.

[0035] Furthermore, the amount of monomer components other than the (meth)acrylic acid ester monomer among the polymer components constituting the inkjet-colored resin particle dispersion shall be the remainder of the total amount of the (meth)acrylic acid ester monomer used and the crosslinking agent described later. Preferably, the content of other monomer components is 0.5 to 70% by mass relative to the total polymer components, from the viewpoint of further exhibiting the effects of the present invention, dispersibility, and reactivity.

[0036] In the present invention, the (total) content of the dyes of group A described above is preferably 1.0% by mass or more, more preferably 2.0% by mass or more, relative to the total polymer components, from the viewpoint of color development, lightfastness, and stability, and more preferably 3.0 to 50.0% by mass, and particularly preferably 5.0 to 40.0% by mass. By setting the content of dyes in group A to 1.0% by mass or more, color development and lightfastness can be achieved. On the other hand, if the content of dyes in group A is less than 1.0% by mass, the color development and lightfastness will be insufficient, and the effects of the present invention cannot be achieved.

[0037] When terpene phenol resin is encapsulated in colored resin particles, the content of terpene phenol resin should be such that A / (A+B) is 0.05 to 0.5, and particularly preferably 0.2 to 0.4, when A is the content of the terpene phenol resin and B is the content of the polymerizable polymer component constituting the colored resin particles, in order to further suppress the bleeding of lines due to dye bleeding and to improve water resistance.

[0038] The polymerizable surfactant that can be used as needed is not particularly limited as long as it is a polymerizable surfactant that is normally used in emulsion polymerization. For example, polymerizable surfactants include anionic or nonionic surfactants, and at least one of the following can be mentioned: Adeka Soap NE-10, NE-20, NE-30, NE-40, SE-10N manufactured by Adeka Co., Ltd., Latemul S-180, S-180A, S-120A manufactured by Kao Corporation, Eleminor JS-20 manufactured by Sanyo Chemical Industries, Ltd., and Aqualon KH-05, KH-10, HS-10, AR-10, RN-10 manufactured by Daiichi Kogyo Seiyaku Co., Ltd. The amount of these polymerizable surfactants used is preferably 0.1 to 50% by mass, relative to the polymerizable polymer component. Furthermore, the content of the crosslinking agent, such as triallyl isocyanurate, is preferably 0 to 50% by mass, more preferably 0.1 to 25% by mass, relative to the polymerizable polymer component.

[0039] In the present invention, in order to further enhance long-term stability, preservative properties, color development, fragrance, and lightfastness, the colored resin particles may contain, along with the dyes of Group A (more preferably terpene phenol resins), preservatives, reducing agents, fragrances, oils and fats, ultraviolet absorbers, and light stabilizers.

[0040] In the present invention, an inkjet colored resin particle dispersion (dispersion liquid) in which colored resin particles are dispersed in water can be obtained by, in the above preferred embodiment, at least one of the above-mentioned dyes of group A (more preferably a terpene phenol resin) is dissolved in the above-mentioned (meth)acrylic acid ester monomer and emulsion polymerization, or by, at least one of the above-mentioned dyes of group A (more preferably a terpene phenol resin) is dissolved after polymerization of a mixed monomer containing the above-mentioned (meth)acrylic acid ester monomer and other monomer components and emulsion polymerization. The amount of colored resin particles in the inkjet colored resin particle dispersion obtained under these manufacturing conditions will vary depending on the blending amounts of the above-mentioned (meth)acrylic acid ester monomer, the above-mentioned dyes of group A, etc., used, polymerization conditions, etc., and it is preferable to manufacture it so that the solid content is 1 to 50% by mass from the viewpoint of manufacturability, workability, efficiency, etc. It is even more preferable to manufacture it so that the solid content is 10 to 40% by mass.

[0041] Furthermore, in the present invention, the average particle size of the colored resin fine particles in the inkjet colored resin particle dispersion obtained will vary depending on the (meth)acrylic acid ester monomer, other monomer species used, the dyes of group A above, the content of each component, the polymerization conditions during polymerization, etc., but it is preferably 10 to 800 nm, more preferably 20 to 400 nm, and even more preferably 30 to 300 nm. By setting the average particle size within the preferred range described above, clogging in the inkjet ejection holes and other areas is prevented, and furthermore, excellent printability is achieved. In this invention, the "average particle diameter" is the histogram-averaged particle diameter based on the scattered light intensity distribution. In this invention (including the examples described later), the value D measured using a particle size distribution analyzer [FPAR1000 (manufactured by Otsuka Electronics Co., Ltd.)] is used. 50 This is the value.

[0042] This inkjet-compatible colored resin particle dispersion offers superior color development and long-term stability compared to conventional materials, while also achieving a high level of water resistance and lightfastness, resulting in an inkjet-compatible colored resin particle dispersion with excellent performance. Furthermore, when containing terpene phenol resin, it provides a colorant that prevents bleeding of lines printed by inkjet, making it useful as a colorant in water-based inkjet ink compositions.

[0043] (Water-based ink composition for inkjet printers) The present invention is characterized by comprising an inkjet-compatible aqueous ink composition comprising a colored resin particle dispersion for inkjet use having the above-described configuration. A preferred inkjet ink composition is one that contains the above-described inkjet colored resin particle dispersion and a solvent. This aqueous inkjet ink composition can be prepared by adding a solvent to the inkjet colored resin particle dispersion having the above configuration and stirring. Resins, dispersants, etc., may be added as needed. There are no particular restrictions on the solvent used for inkjet inks, but specifically, in addition to water (purified water, ion-exchanged water, distilled water, pure water, etc., hereinafter simply referred to as "water"), water-soluble organic solvents can be used as a mixed solvent. The water content is the remainder of the content of each component, and is approximately 1.0 to 50.0% by mass.

[0044] Examples of water-soluble organic solvents that can be used include alkyl alcohols having 1 to 4 carbon atoms such as ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, sec-butyl alcohol, and tert-butyl alcohol; amides such as dimethylformamide and dimethylacetamide; ketones or keto alcohols such as acetone and diacetone alcohol; ethers such as tetrahydrofuran and dioxane; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; alkylene glycols containing 2 to 6 carbon atoms in the alkylene group, such as ethylene glycol, propylene glycol, butylene glycol, triethylene glycol, 1,2,6-hexanetriol, thiodiglycol, hexylene glycol, and diethylene glycol; glycerin; lower alkyl ethers of polyhydric alcohols such as ethylene glycol monomethyl (or ethyl) ether, diethylene glycol methyl (or ethyl) ether, and triethylene glycol monomethyl (or ethyl) ether; and N-methyl-2-pyrrolidone, 2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone. Among these many water-soluble organic solvents, polyhydric alcohols such as diethylene glycol and lower alkyl ethers of polyhydric alcohols such as triethylene glycol monomethyl (or ethyl) ether are preferred. The content of the water-soluble organic solvent is preferably in the range of 3 to 50% by mass, and more preferably in the range of 3 to 30% by mass, relative to the total amount of the ink composition.

[0045] The resin used in inkjet inks is not particularly limited and can be dissolved or dispersed in the solvent blended into the ink. Specifically, examples include acrylic resin, styrene-acrylic resin, styrene resin, polyester resin, phenolic resin, polyamide, polyvinyl butyral, cellulose acetate butyrate, nitrocellulose resin, urethane resin, and vinyl chloride-vinyl acetate copolymer. These can be used individually or in combination of two or more. The type of resin should be selected according to the type of medium. Preferred resins for use as a fixing resin include urethane resin emulsion, acrylic resin emulsion, styrene-acrylic resin emulsion, and styrene resin emulsion, which have excellent functionality. The content of these resins is preferably in the range of 1.0 to 50.0% by mass, and more preferably in the range of 3.0 to 30.0% by mass, relative to the total amount of the ink composition.

[0046] In the aqueous inkjet ink composition of the present invention, the above-described inkjet colored resin particle dispersion can be used as is, or the above-described solvent, and optionally resin and dispersant can be added, and furthermore, various additives commonly used in the field can be included as long as they do not hinder the objective of the present invention. For example, nozzle clogging inhibitors, antioxidants, conductivity modifiers, viscosity modifiers, surfactants, oxygen absorbers, etc. can be added as appropriate. These types are not particularly limited, and those used in the field can be used. In addition, the inkjet colored resin particle dispersion may be diluted with a non-aqueous solvent.

[0047] The content of colored resin particles varies depending on the printing method, but it is preferably 1 to 30% by mass relative to the total amount of the water-based inkjet ink composition in terms of solid content. The viscosity of an aqueous inkjet ink composition varies depending on the nozzle diameter of the inkjet recording system's ejection head and the ejection environment, but it is generally preferable to have a viscosity of 1 to 20 mPa·s at 25°C.

[0048] There are no particular limitations on the inkjet recording method using the aqueous inkjet ink composition of the present invention, and known methods include, for example, a charge control method that ejects the ink composition using electrostatic induction force, a drop-on-demand method (pressure pulse method) that utilizes the vibration pressure of a piezoelectric element, an acoustic inkjet method that converts an electrical signal into an acoustic beam and irradiates the ink composition, using the radiation pressure to eject the ink composition, and a thermal inkjet (bubble jet®) method that heats the ink composition to form bubbles and utilizes the resulting pressure. The recording medium is not particularly limited and can be plain paper, glossy paper, copy paper, specialty paper, cloth, film, OHP sheets, etc.

[0049] The aqueous inkjet ink composition of the present invention, configured in this manner, exhibits excellent color tone and durability without adversely affecting other components, and also boasts excellent dispersion stability, maintaining its sustained effect over a long period. Furthermore, these particles do not impair storage stability or inkjet performance, and the particle size can be made small, eliminating issues such as clogging of nozzles. It achieves a high degree of balance between water resistance, lightfastness, aging stability, and color development, resulting in an exceptionally superior function as an inkjet colorant. Therefore, an aqueous inkjet ink composition suitable for printing using any method, such as piezo, electrostatic, or thermal, and for printing on plain paper, glossy paper, specialty paper, fabric (clothing such as T-shirts), film, and OHP sheets can be obtained. [Examples]

[0050] Next, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples. [Manufacturing Examples 1-8, Comparative Manufacturing Examples 1-5: Manufacturing of inkjet-compatible colored resin particle dispersions (particles 1-10)] Note that the term "part" below refers to the part by mass.

[0051] (Manufacturing Example 1) A 2-liter flask was fitted with a stirrer, reflux condenser, thermometer, nitrogen gas inlet tube, and 1000 ml separatory funnel for monomer input, and placed in a hot water bath. Five parts of glycerin monomethacrylate [Bremmer GLM, NOF Corporation], five parts of sodium 2-sulfoethyl methacrylate [Acrylates SEM-Na, Mitsubishi Chemical Corporation], forty parts of polymerizable surfactant [ADEKA Corporation, Adekarya Soap SR-10, ether sulfate], and 0.5 parts of ammonium persulfate were added, and the internal temperature was raised to 50°C while introducing nitrogen gas. On the other hand, a solution was prepared by mixing a mixed monomer consisting of 55 parts of cyclohexyl methacrylate monomer and 20 parts of n-butyl methacrylate with 40 parts of an oil-soluble dye (Valifast Black 3830, manufactured by Orient Chemical Industry Co., Ltd.) as a dye of group A, 10 parts of a crosslinking agent [triallyl isocyanurate, manufactured by Nippon Chemical Corporation, TAIC], and the remainder being pure water (the remainder when the total composition was 500 parts). This prepared solution was added from the separatory funnel into the flask, which was kept at a temperature of approximately 90°C, under stirring for 3 hours to carry out emulsion polymerization. After further aging for 5 hours, polymerization was completed to obtain a colored resin particle dispersion (dispersion) (particle 1). The methacrylate ester monomer content was 48.6% by mass relative to the total polymer components constituting the colored resin particles, and the dye component content was 29.6% by mass relative to the total polymer components. The average particle size of the colored resin particles was 112 nm.

[0052] (Manufacturing example 2) In the same method as in Production Example 1 described above, an inkjet colored resin particle dispersion (dispersion) (particles 2) was obtained by mixing a mixed monomer consisting of 30 parts of cyclohexyl methacrylate monomer and 50 parts of n-butyl methacrylate with 25 parts of an oil-soluble dye (Valifast Blue 2680, manufactured by Orient Chemical Industry Co., Ltd.) as a dye of Group A. The methacrylate monomer content was 54.5% by mass relative to the total polymer components constituting the colored resin particles, and the dye content was 17.9% by mass relative to the total polymer components. The average particle size of the colored resin particles was 48 nm.

[0053] (Manufacturing Example 3) In the same method as in Production Example 1 described above, an inkjet colored resin particle dispersion (dispersion) (particle 3) was obtained by mixing a mixed monomer consisting of 45 parts of cyclohexyl methacrylate monomer and 35 parts of n-butyl methacrylate with 15 parts of an oil-soluble dye (Oil Pink 314, manufactured by Orient Chemical Industry Co., Ltd.) and 25 parts of a terpene phenol resin (YS Polystar N125, manufactured by Yasuhara Chemical Co., Ltd.) as dyes of Group A. The methacrylate monomer content was 50.0% by mass relative to the total polymer components constituting the colored resin particles, and the dye content was 10.7% by mass relative to the total polymer components. The average particle size of the colored resin particles was 107 nm.

[0054] (Manufacturing example 4) In the same method as in Production Example 1 described above, an inkjet colored resin particle dispersion (dispersion) (particles 4) was obtained by mixing a mixed monomer consisting of 28 parts of cyclohexyl methacrylate monomer and 44 parts of n-butyl methacrylate with 30 parts of a salt-forming dye made from an acidic dye and a basic dye as a dye of Group A (a salt-forming dye made by mixing 15 parts of Spion Yellow CGNH new, manufactured by Hodogaya Chemical Co., Ltd., and 15 parts of Water Yellow 6C, manufactured by Orient Chemical Industry Co., Ltd.). The methacrylate monomer content was 50.6% by mass relative to the total polymer components constituting the colored resin particles, and the dye content was 22.7% by mass relative to the total polymer components. The average particle size of the colored resin particles was 89 nm.

[0055] (Manufacturing example 5) In the above-mentioned Production Example 1, an inkjet colored resin particle dispersion (dispersion) (particles 5) was obtained by the same method as above, except that a solution was prepared by mixing a mixed monomer consisting of 30 parts of cyclohexyl methacrylate monomer and 45 parts of n-butyl methacrylate with 20 parts of oil-soluble dye (Valifast Black 3830, manufactured by Orient Chemical Industry Co., Ltd.), 5 parts of oil-soluble dye (Valifast Red 3312, manufactured by Orient Chemical Industry Co., Ltd.), and 5 parts of oil-soluble dye (Valifast Yellow 1108, manufactured by Orient Chemical Industry Co., Ltd.) as dyes from group A. The methacrylate monomer content was 51.5% by mass relative to the total polymer components constituting the colored resin particles, and the dye content was 22.2% by mass relative to the total polymer components. The average particle size of the colored resin particles was 152 nm.

[0056] (Manufacturing example 6) In the same method as in Production Example 1 described above, an inkjet colored resin particle dispersion (dispersion) (particles 6) was obtained by mixing a mixed monomer consisting of 30 parts of cyclohexyl methacrylate monomer and 45 parts of n-butyl methacrylate with 50 parts of an oil-soluble dye (Oil Orange 201M, manufactured by Orient Chemical Industry Co., Ltd.) as a dye of Group A. The methacrylate monomer content was 45.9% by mass relative to the total polymer components constituting the colored resin particles, and the dye content was 37.0% by mass relative to the total polymer components. The average particle size of the colored resin particles was 203 nm.

[0057] (Manufacturing example 7) In the same method as in Production Example 1 described above, an inkjet colored resin particle dispersion (dispersion) (particles 7) was obtained by mixing a mixed monomer consisting of 45 parts of cyclohexyl methacrylate monomer and 40 parts of n-butyl methacrylate with 7.5 parts of a basic dye (Rhodamine A, manufactured by Taoka Chemical Industries Co., Ltd.) and 5 parts of a terpene phenol resin (YS Polystar N125, manufactured by Yasuhara Chemical Co., Ltd.) as dyes of group A. The methacrylate monomer content was 62.3% by mass relative to the total polymer components constituting the colored resin particles, and the dye content was 5.2% by mass relative to the total polymer components. The average particle size of the colored resin particles was 131 nm.

[0058] (Comparative manufacturing example 1) A colored dispersion (dispersion) for inkjet printing was prepared by mixing 40 parts of an oil-soluble dye (Valifast Black 3830, manufactured by Orient Chemical Industry Co., Ltd.), 40 parts of a surfactant (Emal 2FG, manufactured by Kao Corporation), and 420 parts of water (purified water).

[0059] (Comparative manufacturing example 2) A colored dispersion for inkjet printing was prepared by mixing 30 parts of a salt-forming dye using acid dyes and basic dyes (a salt-forming dye mixed with 15 parts of Spion Yellow CGNH new, manufactured by Hodogaya Chemical Co., Ltd., and 15 parts of Water Yellow 6C, manufactured by Orient Chemical Industry Co., Ltd.), 20 parts of a surfactant (Emal 2FG, manufactured by Kao Corporation), and 460 parts of water (purified water).

[0060] (Comparative manufacturing example 3) A colored dispersion (dispersion) for inkjet printing was prepared by mixing 7.5 parts of a basic dye (Rhodamine A, manufactured by Taoka Chemical Industries, Ltd.), 15.0 parts of a surfactant (Emal 2FG, manufactured by Kao Corporation), and 470 parts of water (purified water).

[0061] (Comparative manufacturing example 4) Following the above manufacturing example 1, a solution was prepared by substituting the oil-soluble dyes of Group A with 20 parts of an acid dye (Valifast Yellow 1101, manufactured by Orient Chemical Industry Co., Ltd.). This prepared solution was added from the separatory funnel into the flask, which was kept at a temperature of approximately 90°C, under stirring for 3 hours to carry out emulsion polymerization. After further aging for 5 hours, polymerization was completed to obtain an inkjet-compatible colored resin particle dispersion (dispersion) (particle 8). The methacrylate monomer content was 54.8% by mass relative to the total polymer components constituting the colored resin particles, and the dye content was 14.8% by mass relative to the total polymer components. The average particle size of the colored resin particles was 61 nm.

[0062] (Comparative manufacturing example 5) A colored resin particle dispersion (dispersion) (particle 9) for inkjet use was obtained using vinyl acetate without using the methacrylate ester monomer of Production Example 3. The vinyl acetate monomer content was 56.7% by mass relative to the total polymer components constituting the colored resin particles, and the dye content was 11.1% by mass relative to the total polymer components. The average particle size of the colored resin particles was 237 nm.

[0063] Using the inkjet-compatible colored resin particle dispersions (dispersions) obtained from manufacturing examples 1-7 and comparative manufacturing examples 1-5 described above, test specimens were prepared using the following methods, and their color development, storage stability, water resistance, and light resistance were evaluated according to the evaluation methods described below. These results are shown in Table 1 below.

[0064] (Method for preparing test specimens) Each of the obtained inkjet-compatible colored resin particle dispersions was prepared by coating it onto "Multi Super Economy" paper (manufactured by ASKUL Corporation) using a bar coater "ROD No. 6" (manufactured by Yasuda Seiki Seisakusho Co., Ltd.), and then evaluating the test pieces after they had been thoroughly dried.

[0065] (Method for evaluating color development) The obtained inkjet-compatible colored resin particle dispersion (dispersion) was visually evaluated using the following criteria. Evaluation criteria: A: The applied area is vibrant and has excellent color development. B: The applied area shows some dullness, and the color development is slightly inferior. C: Significant dullness is visible in the applied area, and the overall color development is poor.

[0066] (Method for evaluating storage stability) Each of the inkjet-compatible colored resin particle dispersions (dispersion liquids) obtained above was placed in a glass mayonnaise bottle (manufactured by AS ONE Corporation), and the presence or absence of precipitates was visually evaluated according to the following evaluation criteria after a period of 2 weeks at a temperature of -10°C. Evaluation criteria: A: No precipitates B: Some precipitation is visible. C: Precipitation is observed throughout, with sediment at the bottom.

[0067] (Method for evaluating water resistance) Using test pieces of each inkjet-compatible colored resin particle dispersion (dispersion) obtained above, the bleeding properties were compared with the initial coated area after immersion in purified water for one day. Evaluation criteria: A: It's the same as it was initially. B: Slight bleeding is visible. C: There is some bleeding throughout.

[0068] (Method for evaluating lightfastness) Using test pieces of each inkjet-compatible colored resin particle dispersion (dispersion) obtained above, the lightfastness was evaluated visually using a Suga Test Instruments X25 xenon weather meter. After 6 hours of irradiation with a xenon arc lamp of 50 W / m2 (300-400 nm) according to JIS L 0843, the visibility was evaluated by shining a 365 nm UV lamp according to the following evaluation criteria. Evaluation criteria: A: High visibility, unchanged from the initial model. B: The applied area is difficult to see, but it is still visible. C: Visibility of the coated area is significantly reduced.

[0069] [Table 1]

[0070] As is clear from the results in Table 1 above, among the inkjet-compatible colored resin particle dispersions (dispersions) obtained above, Production Examples 1 to 7 within the scope of the present invention were found to have excellent color development, storage stability, water resistance, and light resistance. In contrast, the inkjet-use colored resin particle dispersions (dispersions) of Comparative Manufacturing Examples 1 to 5, which fall outside the scope of the present invention, were found to be inferior in any of the following: color development, storage stability, water resistance, or light resistance.

[0071] [Examples 1-7 and Comparative Examples 1-5: Preparation of Aqueous Ink Compositions for Inkjet Printers] Using the inkjet-compatible colored resin particle dispersions (particles 1-9) produced according to the above production examples 1-7 and comparative production examples 1-5, each inkjet-compatible aqueous ink composition was prepared by conventional methods with the following formulations (total amount 100% by mass). Each obtained inkjet-compatible aqueous ink composition was filled into a cartridge of an inkjet device [inkjet printer (PM-3000C, manufactured by Epson)], printed on a support made of copy paper (printing paper), and evaluated for color development, storage stability, water resistance, and light resistance using the evaluation methods described below. These results are shown in Table 2 below.

[0072] Ink composition: (Total 100% by mass) Each colored resin particle dispersion (particles 1 to 9, comparative production examples 1 to 3) 50.0% by mass pH adjuster (triethanolamine) 1.4% by mass Water-soluble organic solvent (propylene glycol) 15.0% by mass Ion-exchanged water 33.6% by mass The solid content of each of the above colored resin particle dispersions (particles 1-8) and the colored resin particle dispersions of comparative manufacturing examples 4-5 is 25.0-40.0% by mass.

[0073] (Method for evaluating color development) The printed area, created using an inkjet device, was visually evaluated according to the following evaluation criteria. Evaluation criteria: A: The printed area is vivid and has excellent color reproduction. B: The printed area shows some dullness, and the color reproduction is slightly inferior. C: Significant dullness is visible in the printed area, and the overall color reproduction is poor.

[0074] (Method for evaluating storage stability) Each of the inkjet ink compositions obtained in the above examples was placed in a glass mayonnaise bottle (manufactured by AS ONE Corporation), and the presence or absence of precipitates was visually evaluated according to the following evaluation criteria after a period of 2 weeks at a temperature of -10°C. Evaluation criteria: A: No precipitates B: Some precipitation is visible. C: Precipitation is observed throughout, with sediment at the bottom.

[0075] (Method for evaluating water resistance) After immersing a support printed with an inkjet device in purified water for one day, the bleeding properties were compared with the initial lines. Evaluation criteria: A: It's the same as it was initially. B: Slight bleeding is visible. C: There is some bleeding throughout.

[0076] (Method for evaluating lightfastness) The lightfastness of the printed areas obtained using each of the water-based inkjet ink compositions obtained in the above examples and comparative examples was evaluated visually using a Suga Test Instruments X25 xenon weather meter. After 6 hours of irradiation with a xenon arc lamp of 50 W / m2 (300-400 nm) according to JIS L 0843, the visibility was evaluated by shining a 365 nm UV lamp according to the following evaluation criteria. Evaluation criteria: A: High visibility, unchanged from the initial model. B: The printed area is difficult to see, but it is still legible. C: The visibility of the printed area is significantly reduced.

[0077] [Table 2]

[0078] Considering Table 2 above, it was found that the water-based inkjet ink compositions of Examples 1 to 8, which fall within the scope of the present invention, are superior in water resistance, light resistance, long-term stability, and color development compared to Comparative Examples 1 to 5, which fall outside the scope of the present invention. Furthermore, they do not bleed through and exhibit excellent coverage. [Industrial applicability]

[0079] The inkjet-compatible colored resin particle dispersion of the present invention can be used as a colorant in aqueous ink compositions, such as those for inkjet applications.

Claims

1. An inkjet-compatible colored resin particle dispersion characterized in that colored resin particles, each composed of at least a (meth)acrylic acid ester monomer represented by the following general formula (X) and at least one dye selected from the following group A, are dispersed in water. 【Chemistry 1】 [In the above formula (I), A is a hydrogen atom (H) or a methyl group (CH ３ ) where R represents a substituent having a hydrogen atom (H), an alkyl group having 1 to 22 carbon atoms, or a polyalkylene glycol chain having 2 to 18 carbon atoms in the alkylene chain, and the substituent having an alkyl group or polyalkylene glycol chain may have a phenyl group, a benzyl group, an epoxy group, a hydroxyl group, a dialkylamino group, an alkoxy group having 1 to 18 carbon atoms, a perfluoroalkyl group having 1 to 18 carbon atoms, or a trialkoxysilyl group as a substituent. Group A: Basic dyes, oil-soluble dyes, acid dyes, and salt-forming dyes which are salt-forming products of basic dyes.

2. The inkjet-use colored resin particle dispersion according to claim 1, characterized in that the colored resin particles further contain a terpene phenol resin.

3. The inkjet-use colored resin particle dispersion according to claim 1 or 2, characterized in that the average particle size of the colored resin particles is 10 to 800 nm.

4. An aqueous inkjet ink composition characterized by comprising the inkjet-colored resin particle dispersion described in claim 1 or 2.

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