JP2019196438A - Coloring resin fine particle and aqueous ink composition for writing instrument - Google Patents

Abstract

To provide a coloring resin fine particle good in sticking tendency and water wiping property in addition to coloring material function, and an ink composition for writing instrument containing the fine particles and suitable for writing instrument such as a marking pen or a ball point pen.SOLUTION: There is provided a coloring resin fine particle obtained by living radical polymerization of a monomer component and a dye by using an RAFT agent, the RAFT agent is at least one kind selected from a dibenzyl tri-thiocarbonate compound represented by the following formula (I). In the formula (I), Ar is phenylene; Rand Rare each independently H, acetoxy, OH, hydroxymethyl, -C(O)-O-CH-Ror -C(O)-N(R)-(CH)n-R, Ris C1 to 5 alkyl having OH at a terminal, C2 to 5 alkyl having OH at a terminal and a neighboring position respectively, C2 to 5 alkenyl having a double bond between a terminal and a neighboring position or the like, Ris C1 to 5 alkyl, n is the number of 1 to 5, and Ris acetoxy or OH.SELECTED DRAWING: None

Description

  The present invention relates to a colored resin fine particle having a combination of other functions in addition to a color material function, and an ink composition for a writing instrument suitable for a writing instrument such as a marking pen and a ballpoint pen containing the colored resin fine particle.

  Conventionally, it is known that a resin emulsion having a specific polymer structure is dyed with a dye and used as a coloring material called a pseudo pigment.

For example, 1) An aqueous dispersion of colored resin fine particles for aqueous ink prepared by emulsion polymerization of a vinyl monomer having an acidic functional group in which a water-soluble basic dye is dissolved in the presence of a polymerizable surfactant (for example, patents) 2) At least a carboxyl group-containing vinyl monomer (A) having an acid functional group solubility in water of 10% by mass or less, acrylic acid or methacrylic acid, and a linear or cyclic alcohol having 2 to 18 carbon atoms A dispersion of colored resin fine particles for aqueous ink in which colored resin fine particles composed of an ester monomer (B) and a basic dye or an oil-soluble dye are dispersed in water, and an aqueous ink composition for a writing instrument using the same A thing (for example, refer patent documents 2 and 3) is known.
However, the color material composed of the above colored resin fine particles has only a simple function such as only a color material function and improved drawing dryness, and further improvement of the colored resin fine particles is desired at present. is there.

On the other hand, RAFT agents (reversible addition-cleavage chain transfer agents) are conventionally known as agents used in controlled living radical polymerization methods. For example, various agents such as dithiobenzoates and trithiocarbonates are used. Are known.
However, at least until now, the colored resin fine particles obtained by subjecting monomer components and dyes to living radical polymerization using a specific RAFT agent can provide other functions such as adhesion as well as color material functions. It is not known.

JP-A-10-259337 (Claims, Examples, etc.) JP-A-2006-196623 (Claims, Examples, etc.) International Publication WO2016 / 163291 (Claims, Examples, etc.)

  The present invention is intended to solve the above-mentioned problems of the prior art and the current situation. In addition to the coloring material function, the colored resin fine particles that have good adhesion, water wiping properties, etc., and the colored resin fine particles It aims at providing the ink composition for writing tools suitable for writing tools, such as a marking pen and a ball-point pen to contain.

  As a result of intensive studies in view of the above-described conventional problems, the present inventor is a colored resin fine particle obtained by living radical polymerization of at least a monomer component and a dye using a RAFT agent, the RAFT agent As a result, the inventors have found that the above-mentioned objective colored resin fine particles and ink composition for writing instruments can be obtained by using a specific material, and the present invention has been completed.

〔式（Ｉ）中、Ａｒはフェニレン基を表し、Ｒ_１，Ｒ_２は同一であっても、異なっても良く、水素原子、アセトキシ基、ヒドロキシ基、ヒドロキシメチル基であり、または、式：−Ｃ（Ｏ）−Ｏ−ＣＨ_２−Ｒ_３（ここで、Ｒ_３は末端にヒドロキシ基を有する炭素数１〜５のアルキル基、末端及びその隣接位にそれぞれヒドロキシ基を有する炭素数２〜５のアルキル基、末端及びその隣接位間に二重結合を有する炭素数２〜５のアルケニル基または末端及びその隣接位にエポキシを有する炭素数２〜５のアルキル基を表す。）であり、または、式：−Ｃ（Ｏ）−Ｎ（Ｒ_４）−（ＣＨ_２）ｎ−Ｒ_５（ここで、Ｒ_４は炭素数１〜５のアルキル基、ｎは１〜５の数、Ｒ_５はアセトキシ基、ヒドロキシ基を表す。）である。〕
本発明の筆記具用インク組成物は、上記構成の着色樹脂微粒子を含有することを特徴とする。 That is, the colored resin fine particles of the present invention are colored resin fine particles obtained by living radical polymerization of at least a monomer component and a dye using a RAFT agent, and the RAFT agent is represented by the following formula (I). It is at least one selected from dibenzyltrithiocarbonate compounds.

[In the formula (I), Ar represents a phenylene group, and R ₁ and R ₂ may be the same or different, and are a hydrogen atom, an acetoxy group, a hydroxy group, a hydroxymethyl group, or the formula: —C (O) —O—CH ₂ —R ₃ (where R ₃ is an alkyl group having 1 to 5 carbon atoms having a hydroxy group at the terminal, and 2 to 2 carbon atoms each having a hydroxy group at the terminal and its adjacent position) 5 represents an alkyl group having 5 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms having a double bond between the terminal and its adjacent position, or an alkyl group having 2 to 5 carbon atoms having an epoxy at the terminal and its adjacent position. Or the formula: —C (O) —N (R ₄ ) — (CH ₂ ) n —R ₅ (where R ₄ is an alkyl group having 1 to 5 carbon atoms, n is a number of 1 to ₅ , R ₅ Represents an acetoxy group or a hydroxy group. ]
The ink composition for a writing instrument of the present invention contains the colored resin fine particles having the above-described configuration.

  According to the present invention, there is provided a colored resin fine particle having good colorant function, fixing property, water wiping property, and the like, and a writing tool ink composition containing the colored resin fine particle and suitable for a writing tool such as a marking pen and a ballpoint pen. Provided.

〔式（Ｉ）中、Ａｒはフェニレン基を表し、Ｒ_１，Ｒ_２は同一であっても、異なっても良く、水素原子、アセトキシ基、ヒドロキシ基、ヒドロキシメチル基であり、または、式：−Ｃ（Ｏ）−Ｏ−ＣＨ_２−Ｒ_３（ここで、Ｒ_３は末端にヒドロキシ基を有する炭素数１〜５のアルキル基、末端及びその隣接位にそれぞれヒドロキシ基を有する炭素数２〜５のアルキル基、末端及びその隣接位間に二重結合を有する炭素数２〜５のアルケニル基または末端及びその隣接位にエポキシを有する炭素数２〜５のアルキル基を表す。）であり、または、式：−Ｃ（Ｏ）−Ｎ（Ｒ_４）−（ＣＨ_２）ｎ−Ｒ_５（ここで、Ｒ_４は炭素数１〜５のアルキル基、ｎは１〜５の数、Ｒ_５はアセトキシ基、ヒドロキシ基を表す。）である。〕 Hereinafter, embodiments of the present invention will be described in detail.
The colored resin fine particles of the present invention are colored resin fine particles obtained by living radical polymerization of at least a monomer component and a dye using a RAFT agent, and the RAFT agent is a diester represented by the following formula (I). It is at least one selected from benzyltrithiocarbonate compounds.

[In the formula (I), Ar represents a phenylene group, and R ₁ and R ₂ may be the same or different, and are a hydrogen atom, an acetoxy group, a hydroxy group, a hydroxymethyl group, or the formula: —C (O) —O—CH ₂ —R ₃ (where R ₃ is an alkyl group having 1 to 5 carbon atoms having a hydroxy group at the terminal, and 2 to 2 carbon atoms each having a hydroxy group at the terminal and its adjacent position) 5 represents an alkyl group having 5 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms having a double bond between the terminal and its adjacent position, or an alkyl group having 2 to 5 carbon atoms having an epoxy at the terminal and its adjacent position. Or the formula: —C (O) —N (R ₄ ) — (CH ₂ ) n —R ₅ (where R ₄ is an alkyl group having 1 to 5 carbon atoms, n is a number of 1 to ₅ , R ₅ Represents an acetoxy group or a hydroxy group. ]

The monomer component (monomer) that can be used in the present invention is not limited as long as it is a polymer by living radical polymerization using the above-described specific RAFT agent and becomes colored resin fine particles. Examples include various monomers used as monomer components of fine particles.
Preferably, a vinyl monomer is used from the viewpoints of various required characteristics depending on applications, a wide variety of usable monomers, and excellent color developability.
The vinyl monomer to be used is not particularly limited. For example, methyl (meth) acrylate, ethyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate Acrylate monomers such as dimethylaminoethyl acrylate and diethylaminoethyl acrylate, methacrylate monomers such as dimethylaminoethyl methacrylate, styrene monomers such as styrene and p-methylstyrene, methyl vinyl ether, Alkyl vinyl ethers such as ethyl vinyl ether, vinyl ester monomers such as vinyl acetate and vinyl butyrate, N-alkyl substituted (meth) acrylamides such as N-methylacrylamide and N-ethylacrylamide, acrylonitrile, methacrylo Nitrile monomers such as tolyl, polyfunctional monomers such as divinylbenzene, ethylene glycol di (meth) acrylate, polyethylene glycol mono (meth) acrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate Etc. Moreover, the vinyl monomer which has various functional groups, such as an acidic functional group (a carboxyl group, a sulfone group, etc.), a cyano group, a triazine ring, and a fluorine group, may be sufficient.
Examples of vinyl monomers having an acidic functional group (carboxyl group, sulfone group, etc.) include phthalic acid-2-methacryloyloxyester, phthalic acid-2-acryloyloxyester, hexahydrophthalic acid-2-methacryloyloxyethyl, Examples include hexahydrophthalic acid-2-acryloyloxyethyl, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid, and 2-methacryloyloxyethyl-2-hydroxyethyl-phthalic acid.
Such a monomer component (monomer) can be used at least one (each alone or in combination of two or more, the same shall apply hereinafter). In the present specification, the expression “(meth) acrylic acid” represents “acrylic acid and / or methacrylic acid”, and the expression “(meth) acrylate” represents “acrylate and / or methacrylate”. .

In the present invention, preferable monomer components include, for example, the above-mentioned acrylic acid or methacrylic acid esters, hydrophobic styrenes such as styrene and methylstyrene, and the like from the viewpoint of obtaining colored resin fine particles having a deep color and excellent color developability. And at least one monomer selected from water-based monomers described later can be used.
Examples of esters of acrylic acid or methacrylic acid that can be preferably used include, for example, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, (meth ) Isobutyl acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate , Palmitic acid (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) acrylate, and the like.

  Examples of aqueous monomers that can be used include 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 and the like (each single or a mixture of two or more).

  Furthermore, in the present invention, in addition to the monomer (monomer) described above, a crosslinkable monomer having two or more polymerizable double bonds in one molecule may be used. Typical examples of monomers having crosslinkability include divinylbenzene, ethylene glycol di (meth) acrylate, polyethylene glycol mono (meth) acrylate, trimethylolpropane trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, etc. Is mentioned.

As long as the dye used in the present invention can be dissolved in the monomer component, the kind thereof is not particularly limited, and among basic dyes, oil-soluble dyes, direct dyes, acid dyes, azoic dyes, aqueous dyes, reactive dyes, and the like, It is suitably selected according to the type of monomer used.
In the present invention, basic dyes and oil-soluble dyes are preferably used from the viewpoint of color developability and stability. In addition, dyes commonly used in writing instrument inks, such as coumarins, perylenes, dicyanopinyls, azos (eg, pyridoneazos, disazos, trisazos, benzeneazos, heterocyclic azos), quinophthalones Aminopyrazole, methine, dicyanoimidazole, indoaniline, and phthalocyanine can also be suitably used. These dyes may be used in combination of two or more.

Examples of basic dyes that can be preferably used include di- and triarylmethane dyes; azine dyes (including nigrosine), quinazine imine dyes such as oxazine dyes and thiazine dyes; xanthene dyes; triazole azo dyes; Azo dyes; benzothiazole azo dyes; azo dyes; polymethine, azomethine, azamethine and other methine dyes; anthraquinone dyes; basic dyes such as phthalocyanine dyes, and the like. Is preferably a water-soluble basic dye.
Specific examples of basic dyes include C.I. I. Basic yellow (-1, -2, -9, -80, etc.), C.I. I. Basic orange (-1, -2, -7, -34, etc.), C.I. I. Basic red (-1, -2, -3, -53, etc.), C.I. I. Basic violet (-1, -2, -3, -39, etc.), C.I. I. Basic blue (-1, -2, -5, -88, etc.), C.I. I. Basic green (-1, -4, -6, -10 etc.), C.I. I. Basic brown (-1, -2, -4, -15 etc.), C.I. I. Each No. described in the COLOR INDEX such as basic black (-1, -2, -7, -8, etc.). The dye of each color is mentioned.
These commercially available products can also be used. For yellow basic dyes, AIZEN CATILON YELLOW GLH (trade name manufactured by Hodogaya Chemical Co., Ltd.) and the like, for red basic dyes, AIZEN CATILON RED BLH, AIZEN CATILON RED Blue basic dyes such as RH (trade name, manufactured by Hodogaya Chemical Co., Ltd.), Diacryl Supra Brilliant Red 2G (trade name, manufactured by Mitsubishi Chemical Corporation), Sumicryl Red B (trade name, manufactured by Sumitomo Chemical Co., Ltd.), etc. In the case of brown basic dyes such as AIZEN CATHILOON TURQUOISE BLUE LH (trade name manufactured by Hodogaya Chemical Industry Co., Ltd.) and other basic green dyes, such as Diacryl Supra Brilliant Green 2GL (trade name manufactured by Mitsubishi Chemical Corporation) anus Brown R (Nippon Chemical Co., Ltd. under the trade name), AIZEN CATHILON BROWN GH (Hodogaya Chemical Co., Ltd. under the trade name), and the like.

Examples of oil-soluble dyes that can be preferably used include commercially available monoazo, disazo, metal complex monoazo, anthraquinone, phthalocyanine, triarylmethane, and the like. Further, a salt-forming oil-soluble dye in which a functional group such as an acid / basic dye is substituted with a hydrophobic group can also be used.
Examples of yellow type include C.I. I. Solvent yellow 114, 116; I. Solvent Orange 67; I. Solvent Red 122, 146; I. Solvent Blue 5, 36, 44, 63, 70, 83, 105, 111; I. Solvent Black 3, 7, 27, 29;
Specific examples of commercially available oil-soluble dyes include blue dye SBN blue 701 (Hodogaya Chemical Co., Ltd.), blue dye oil blue 650 (Orient Chemical Co., Ltd.), blue dye savinyl blue GLS (Clariant Co.), red Dye SOC-1-0100 (manufactured by Orient Chemical Co., Ltd.), Oil Black 860, Oil Pink 314, Oil Yellow 3G, Varifast Pink 2310N, Red 3312, Yellow CGHNnew, Yellow 1108, Black 3830 (Orient Chemical Industries) For example).

  The colored resin fine particle of the present invention is a living radical polymerization using at least one RAFT agent selected from dibenzyltrithiocarbonate compounds represented by formula (I) at least with the above-mentioned monomer component and the above-mentioned dye. The production (polymerization process) is obtained by adding a monomer component such as a vinyl monomer such as the above (meth) acrylic acid cyclohexyl monomer or a vinyl monomer such as the above (meth) acrylic acid cyclohexyl monomer and the like. In a mixed monomer containing other hydrophobic vinyl monomers and the like, a dye such as the above basic dye or oil-soluble dye is dissolved, and ammonium persulfate or the like is used as a polymerization initiator, and a polymerization initiator is further used in combination with a reducing agent, Dibenzyltriti represented by the formula (I) as a RAFT agent (reversible addition-fragmentation chain transfer agent) And at least one selected from carbonates compound, and further cross-linking agent, if desired, can be prepared such as by living radical polymerization using a polymerizable surfactant (emulsifier). Moreover, although the said dyeing | staining was performed simultaneously with living radical polymerization, you may dye | stain by dissolving dyes, such as a basic dye and an oil-soluble dye, after living radical polymerization.

〔式（Ｉ）中、Ａｒはフェニレン基を表し、Ｒ_１，Ｒ_２は同一であっても、異なっても良く、水素原子、アセトキシ基、ヒドロキシ基、ヒドロキシメチル基であり、または、式：−Ｃ（Ｏ）−Ｏ−ＣＨ_２−Ｒ_３（ここで、Ｒ_３は末端にヒドロキシ基を有する炭素数１〜５のアルキル基、末端及びその隣接位にそれぞれヒドロキシ基を有する炭素数２〜５のアルキル基、末端及びその隣接位間に二重結合を有する炭素数２〜５のアルケニル基または末端及びその隣接位にエポキシを有する炭素数２〜５のアルキル基を表す。）であり、または、式：−Ｃ（Ｏ）−Ｎ（Ｒ_４）−（ＣＨ_２）ｎ−Ｒ_５（ここで、Ｒ_４は炭素数１〜５のアルキル基、ｎは１〜５の数、Ｒ_５はアセトキシ基、ヒドロキシ基を表す。）である。〕 In the present invention, the monomer component and the dye are polymerized by living radical polymerization using at least one RAFT agent selected from dibenzyltrithiocarbonate compounds represented by the following formula (I). .

[In the formula (I), Ar represents a phenylene group, and R ₁ and R ₂ may be the same or different, and are a hydrogen atom, an acetoxy group, a hydroxy group, a hydroxymethyl group, or the formula: —C (O) —O—CH ₂ —R ₃ (where R ₃ is an alkyl group having 1 to 5 carbon atoms having a hydroxy group at the terminal, and 2 to 2 carbon atoms each having a hydroxy group at the terminal and its adjacent position) 5 represents an alkyl group having 5 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms having a double bond between the terminal and its adjacent position, or an alkyl group having 2 to 5 carbon atoms having an epoxy at the terminal and its adjacent position. Or the formula: —C (O) —N (R ₄ ) — (CH ₂ ) n —R ₅ (where R ₄ is an alkyl group having 1 to 5 carbon atoms, n is a number of 1 to ₅ , R ₅ Represents an acetoxy group or a hydroxy group. ]

Living radical polymerization generally includes reversible addition-fragmentation chain transfer (RAFT) polymerization, atom transfer radical polymerization (ATRP), nitroxide-mediated radical polymerization (NMP). polymerization), polymerization method via organic tellurium compound (TERP; (Organotellurium-mediated living radical polymerization, commonly known as TERP)), but the present invention, among other things, imparts other properties in addition to color development as colored resin fine particles It is possible to easily synthesize a polymer having functional groups at both ends of the molecule, and further, it does not include a metal catalyst and does not require the work of post-treatment. Living radical weight using at least one RAFT agent selected from benzyltrithiocarbonate compounds It is in what is made.
In the present invention, compared with conventional radical polymerization (emulsion polymerization, etc.) of colored resin fine particles, by using colored resin particles obtained by living radical polymerization using the specific RAFT agent, in addition to the colorant function, cohesive force Moreover, since the characteristic which has adhesiveness is expressed, the colored resin microparticles | fine-particles from which adhesiveness, water-wiping property, etc. become favorable can be obtained.

The living radical polymerization using the RAFT agent is characterized by using at least one RAFT agent selected from at least a polymerization initiator and a dibenzyltrithiocarbonate compound represented by the above formula (I). This living radical polymerization by RAFT agent can be applied to various monomer components (monomers) used for colored resin particles, can be applied to a wide range of reaction conditions, colorant function, fixing property, water wiping Compared with other living radical polymerizations, it is excellent in specificity, productivity, and the like in that a good function such as a property can be imparted.
In the present invention, the RAFT agent that can be used is at least one selected from the dibenzyltrithiocarbonate compounds represented by the above formula (I), and in the formula (I), Ar is a phenylene group. , R ₁ and R ₂ may be hydrogen atoms, acetoxy groups, hydroxy groups or hydroxymethyl groups. R ₁ and R _{2 in} formula (I) may be the same or different. R ₁ and R ₂ are represented by the formula: —C (O) —O—CH ₂ —R ₃ , where R ₃ is an alkyl group having 1 to 5 carbon atoms having a hydroxy group at the terminal, a terminal And an alkyl group having 2 to 5 carbon atoms each having a hydroxy group at its adjacent position, an alkenyl group having 2 to 5 carbon atoms having a double bond between the terminal and its adjacent position, or a carbon having an epoxy at its terminal and its adjacent position What is a C2-C5 alkyl group is mentioned. Further, R ₁ and R ₂ are represented by the formula: —C (O) —N (R ₄ ) — (CH ₂ ) n—R ₅ , R ₄ is an alkyl group having 1 to 5 carbon atoms, and n is 1 The number of ˜5, R ₅ is an acetoxy group or a hydroxy group.
Preferably, R ₁ and R ₂ are the same from the viewpoint of further exerting the effects of the present invention.

Examples of the dibenzyltrithiocarbonate compound represented by the above formula (I) that can be specifically used include, for example, S, S-dibenzyltrithiocarbonate, wherein R ₁ and R ₂ are hydrogen atoms, R ₁ , bis (4-hydroxybenzyl) trithiocarbonate in which R ₂ becomes a hydroxy group, bis (4-hydroxymethylbenzyl) trithiocarbonate in which R ₁ and R ₂ become a hydroxymethyl group, R ₁ , R ₂ Bis (4-acetoxybenzyl) trithiocarbonate, wherein R ₁ and R ₂ are represented by the formula: —C (O) —O—CH ₂ —R ₃ , and the terminal is a hydroxy group (hydroxyl) terminal Bis [4- (2-hydroxyethoxycarbonyl) benzyl] trithiocarbonate, bis [4- (3-hydroxypropoxycarbonyl) benzyl] tri Okarubonato, bis [4- (6-hydroxyhexyl oxy) benzyl] _{trithiocarbonate,} R 1, _{R 2} has the formula: -C (O) _-O-CH represented termini diol terminated with 2 -R ₃ and Bis [4- (2,3-dihydroxypropoxycarbonyl) benzyl] trithiocarbonate, R ₁ and R ₂ are represented by the formula: —C (O) —O—CH ₂ —R ₃ and the terminal is an allyl terminal. Bis (4-allyloxycarbonylbenzyl) trithiocarbonate, R ₁ , R ₂ is represented by the formula: —C (O) —O—CH ₂ —R ₃ and has a terminal and an adjacent position with bis [ 4- (2,3-epoxypropoxycarbonyl) benzyl] trithiocarbonate, R ₁ , R ₂ is represented by the formula: —C (O) —N (R ₄ ) — (CH ₂ ) n—R ₅ and is terminated. Aceti Bis {4- [ethyl- (2-acetyloxyethyl) carbamoyl] benzyl} trithiocarbonate, bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate, etc. There is at least one kind.
Production of various dibenzyltrithiocarbonate compounds represented by the above formula (I) is known, and X—CH ₂ —Ar—R ₁ [X represents halogen, Ar represents a phenylene group, and R ₁ represents The compound represented by the same as R _{1 in} (I) above can be obtained by trithiocarbonate conversion using trithiocarbonate. Moreover, if there exists a commercial item, they can be used.

By using the dibenzyltrithiocarbonate compound represented by the above formula (I) as the RAFT agent, the obtained colored resin particles exhibit the characteristics of having cohesive strength and adhesiveness in addition to the colorant function. In addition, colored resin fine particles having good adhesion, water wiping properties and the like are obtained.
The RAFT agent comprising the dibenzyltrithiocarbonate compound represented by the above formula (I) is preferably selected in accordance with the reactivity of the monomer (monomer). In the polymerization of the colored resin fine particles, bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate is preferably used from the viewpoint of dispersion stability.

  The amount of the dibenzyltrithiocarbonate compound represented by the above formula (I) to be used is preferably 1 to 40% by mass, and 10 to 20% by mass with respect to the total amount of the monomer (monomer). More preferred. If the amount of the RAFT agent used is less than 1% by mass or exceeds 40% by mass, it tends to be difficult to control the reaction suitably.

As specific production of the colored resin fine particles of the present invention, for example, the above dyes such as the above basic dye and oil-soluble dye are dissolved in a vinyl monomer, and polymerization of ammonium persulfate, potassium persulfate, hydrogen peroxide, etc. is started. In addition, as a polymerization initiator further using a reducing agent in combination, and using the dibenzyltrithiocarbonate compound represented by the above formula (I), triallyl isocyanurate, triallyl isocyanurate, polyethylene glycol dimethacrylate , Polypropylene glycol dimethacrylate, pentaerythritol acrylate, ditrimethylolpropane acrylate, dipentaerythritol acrylate, methoxylated bisphenol A methacrylate, pentaerythritol methacrylate, ditrimethylolpropane methacrylate Cross-linking agents such as dipentaerythritol methacrylate, ethoxylated polyglycerin methacrylate, and polyoxyethylene-1- (allyloxymethyl) -alkyl ether ammonium sulfate, ether sulfate, polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate, poly Oxyethylene nonyl propenyl phenyl ether, ammonium polyacrylate, ammonium styrene-maleic acid copolymer, polyoxyethylene alkyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyalkylene decyl ether, polyoxyethylene Tridecyl ether, alkylbenzene sulfonate, dioctyl sulfosuccinate, Polymerizable surfactants (emulsifiers) such as sodium uryl sulfate, polyoxyethylene alkyl ether phosphate, polyoxyethylene styrenated phenyl ether phosphate, polyoxyethylene styrenated phenyl ether sulfate, polyoxyethylene alkyl ether sulfate ) Is used for living radical polymerization (emulsion polymerization) to obtain a dispersion of colored resin fine particles, and the resulting dispersion is dried to obtain colored resin fine particles.
Moreover, although the said dyeing | staining was performed simultaneously with living radical polymerization, you may dye | stain by dissolving dyes, such as a basic dye and an oil-soluble dye, after living radical polymerization.
It is preferable to further use a crosslinking agent such as triallyl isocyanurate because the heat resistance, mechanical properties, hydrolysis resistance, and weather resistance of the colored resin fine particles can be further improved.

  In the present invention, in the living radical polymerization, an appropriate amount of a monomer having a reactive crosslinking group such as an epoxy group, a hydroxymethylamide group, an isocyanate group, or a polyfunctional monomer having two or more vinyl groups is used. You may mix | blend and bridge | crosslink.

In the present invention, among the polymer components constituting the colored resin fine particles, the content of the methacrylic acid (meth) acrylate monomer preferably used is 30% by mass or more based on the total polymer components constituting the colored resin fine particles. Is preferable, more preferably 30 to 95% by mass, and particularly preferably 30 to 70% by mass.
In the present invention, the “total polymer component” refers to a polymerizable component constituting the colored resin fine particles. Specifically, the total of the monomer component, the crosslinking agent, the polymerizable surfactant, and the polymerizable dye. Say quantity.

In the present invention, the total content of the dyes such as the basic dye and the oil-soluble dye is preferably 15 with respect to all polymer components from the viewpoints of color developability, sufficient line density, and stability. It is preferable to set it as mass% or more, More preferably, it is 15-50 mass%, Especially preferably, it is desirable to set it as 15-40 mass%.
By setting the dye content to 15% by mass or more, sufficient color developability and sufficient stroke density can be exhibited. On the other hand, when the dye content is less than 15% by mass, color developability is sufficient. It will not be.

The polymerizable surfactant that can be used as needed is not particularly limited as long as it is a polymerizable surfactant that is usually used for the polymerization such as the living radical polymerization, but for example, a polymerizable surfactant. As an anionic or nonionic polymerizable surfactant, Adeka Soap NE-10, NE-20, NE-30, NE-30, NE-40, SE-10N manufactured by Adeka Co., Ltd. At least 1 such as Latemul S-180, S-180A, S-120A, Eleminol JS-20, Sanyo Chemical Industries, Ltd., Aqualon KH-10, manufactured by Daiichi Kogyo Seiyaku Co., Ltd. Species are mentioned. The amount of these polymerizable surfactants used is 0 to 50% by mass, preferably 0.1 to 50% by mass, based on the total amount of the monomers.
The content of the crosslinking agent such as triallyl isocyanurate is 0 to 50% by mass, preferably 0.1 to 25% by mass, based on the total amount of the monomers.

In the present invention, the weight average molecular weight (Mw) of the colored resin fine particles is not particularly limited as long as the effect of the present invention is exhibited.
The present invention, as described above, is a colored resin fine particle obtained by living radical polymerization of at least a monomer component and a dye using the dibenzyltrithiocarbonate compound represented by the above formula (I), for example, Living with a dibenzyltrithiocarbonate compound that dissolves a dye such as the above basic dye or oil-soluble dye in at least the above-mentioned (meth) acrylic acid cyclohexyl monomer and becomes a RAFT agent of the above formula (I) Dibenzyltrithio represented by the above formula (I) by carrying out radical polymerization (emulsion polymerization) or at least a mixed monomer containing a vinyl monomer such as the above-mentioned (meth) acrylic acid cyclohexyl monomer and other monomer components After polymerization using a carbonate compound, dyes such as basic dyes and oil-soluble dyes are dissolved and dyed. To obtain a dispersion of colored resin fine particles in which 20 to 50% by weight of colored resin fine particles are dispersed in water as the resin solids, and to obtain colored resin fine particles by drying the dispersion. Become.

Further, in the present invention, the average particle diameter of the colored resin fine particles obtained is such as vinyl monomer such as (meth) acrylic acid cyclohexyl monomer, other monomer species used, content, RAFT agent species and the amount used, polymerization Although it varies depending on the polymerization conditions in this case, it is preferably 20 to 300 nm, more preferably 40 to 150 nm, and still more preferably 60 to 110 nm.
By setting the average particle size within the above preferable range, the pen core of a writing instrument such as a sign pen, a marking pen, or a ballpoint pen is not clogged, and the storage stability is further improved.
The “average particle diameter” defined in the present invention is a histogram average particle diameter based on the scattered light intensity distribution. In the present invention (including examples described later), a particle size distribution measuring apparatus [FPAR1000 (manufactured by Otsuka Electronics Co., Ltd.) at] is the value of the measured value D _50.

The reason why the colored resin fine particles of the present invention can obtain colored resin fine particles having good color developability and stability over time, as well as excellent fixing property, water wiping property, etc. is presumed as follows.
That is, in the present invention, the colored resin fine particles obtained by living radical polymerization using at least a monomer component and a dye using the dibenzyltrithiocarbonate compound represented by the above formula (I) have a uniform low molecular weight distribution. Therefore, since it is highly redispersible in water after drying, colored resin fine particles that have good adhesion, water wiping properties, etc. in addition to the above colorant functions can be obtained. It is useful as a coloring material for a water-based ink composition for writing instruments suitable for writing instruments such as pens and ballpoint pens.

The water-based ink composition for a writing instrument according to the present invention is characterized by containing at least the colored resin fine particles having the above-described configuration or a dispersion thereof, a water-soluble organic solvent, and water.
Examples of water-soluble organic solvents that can be used include ethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,2-butane. Diol, 2,3-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2,5-hexanediol, 3-methyl 1,3 -Butanediol, 2-methylpentane-2,4-diol, alkylene glycols such as 3-methylpentane-1,3,5 triol, 1,2,3-hexanetriol, and polyalkylene glycols such as polyethylene glycol and polypropylene glycol , Glycerol, jig Glycerols such as serol and triglycerol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dialkylene glycol mono-n-butyl ether and other lower alkyl ethers of N-methyl-2-pyrrolidone , 1,3-dimethyl-2-imidazolidinone and the like.

In addition, for example, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, hexyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, benzyl alcohol, dimethylformamide, Water-soluble solvents such as amides such as diethylacetamide and ketones such as acetone can also be mixed.
The content of these water-soluble organic solvents varies depending on the type of writing instrument such as sign pens, marking pens, and ballpoint pens, and is 1 to 40% by mass relative to the total amount of the ink composition. Therefore, it is particularly effective for an ink composition of 10% by mass or less, more preferably 3 to 8% by mass.

The content of water (tap water, purified water, ion exchange water, distilled water, pure water, etc.) is preferably 30 to 90% by mass, more preferably 40 to 60% by mass, based on the total amount of the ink composition.
The content of the colored resin fine particles varies depending on the type of writing instrument, the outflow mechanism (pen core, ballpoint pen), etc., but it is 1 to 30% by mass with respect to the total amount of the aqueous ink composition for writing instruments in terms of solid content. Is preferred.

In the water-based ink composition for a writing instrument of the present invention, a preservative or antifungal agent, a pH adjuster, an antifoaming agent, and the like can be appropriately selected and used as necessary within a range not impairing the effects of the present invention. .
For example, pH adjusters include ammonia, urea, monoethanolamine, diethanolamine, triethanolamine, aminomethylpropanol, sodium tripolyphosphate, sodium carbonate and other alkali metal salts of carbonic acid and phosphoric acid, and alkali metal water such as sodium hydroxide. There may be mentioned at least one kind such as an oxide.

As preservatives or antifungal agents, phenol, sodium omadin, sodium pentachlorophenol, 1,2-benzisothiazoline 3-one, 2,3,5,6-tetrachloro-4 (methylphonyl) pyridine, benzoic acid and sorbine Examples thereof include at least one of an acid, an alkali metal salt of dehydroacetic acid, a benzimidazole compound, and the like.
Lubricants such as phosphate esters, polyalkylene glycol derivatives such as polyoxyethylene lauryl ether, fatty acid alkali salts, nonionic surfactants, fluorosurfactants such as perfluoroalkyl phosphate esters, dimethylpolysiloxane polyethylene glycol Examples include at least one of polyether-modified silicone such as an adduct.

  The water-based ink composition for a writing instrument of the present invention comprises at least a colored resin fine particle for water-based ink or a dispersion thereof, a water-soluble solvent, and other components for writing instruments (for ballpoint pens, marking pens, etc.). A writing instrument that is appropriately combined according to the application, mixed by stirring with a stirrer such as a homomixer, homogenizer, or disper, and if necessary, by removing coarse particles in the ink composition by filtration or centrifugation. An aqueous ink composition can be prepared.

The writing instrument of the present invention is equipped with a water-based ink composition for a writing instrument having the above composition, and includes, for example, a pen tip portion such as a ballpoint pen tip, a fiber tip, a felt tip, a plastic tip, a fiber core, and a porous core. Mounted on ballpoint pens, marking pens, etc.
As a ballpoint pen, the water-based ink composition for writing instruments having the above composition is accommodated in an ink container (refill) for ballpoint pens and is not compatible with the water-based ink composition for writing instruments having the above composition contained in the ink container. In addition, a substance having a specific gravity smaller than that of the water-based ink composition, for example, polybutene, silicone oil, mineral oil, or the like is accommodated as an ink follower.
The structures of the ballpoint pen and the marking pen are not particularly limited. For example, a collector structure (ink holding mechanism) in which the shaft tube itself is used as an ink container and the water-based ink composition for a writing instrument having the above configuration is filled in the shaft tube. It may be a direct liquid ballpoint pen or a marking pen provided.

  In the water-based ink composition for a writing instrument of the present invention configured as described above, the coloring material contains at least the colored resin fine particles for water-based ink having the above-described configuration or a dispersion thereof, a water-soluble solvent, and water. In addition to the function, a water-based ink composition for a writing instrument suitable for writing instruments such as a sign pen, a marking pen, and a ballpoint pen, which has good adhesion and water wiping properties, can be obtained.

  Next, the present invention will be described in more detail with reference to production examples, examples, and comparative examples, but the present invention is not limited to the following examples.

[Production Examples 1 to 11: Production of colored resin fine particle dispersions (particles 1 to 11)]
According to the following Production Examples 1 to 11, dispersions of each colored resin fine particle were produced. In addition, the following "part" represents a mass part.

(Production Example 1)
A 2 liter flask was equipped with a stirrer, reflux condenser, thermometer, nitrogen gas inlet tube, 1000 ml separatory funnel for monomer addition, set in a hot water tank, 329.5 parts distilled water, glycerin monomethacrylate [Blemmer GLM , NOF Corporation] 5 parts, 2-sulfoethyl sodium methacrylate [acrylic ester SEM-Na, manufactured by Mitsubishi Chemical Co.] 5 parts, polymerizable surfactant [ADEKA Corporation, Adeka Soap SE-10N, ether sulfate 20 parts and 0.5 part of ammonium persulfate were charged, and the internal temperature was raised to 50 ° C. while introducing nitrogen gas.

On the other hand, in a mixed monomer composed of 55 parts of cyclohexyl methacrylate monomer and 35 parts of n-butyl methacrylate as another monomer, 40 parts of an oil-soluble dye [Savinyl Blue GLS, manufactured by Clariant Co., Ltd.], a crosslinking agent [triallyl Isocyanurate, Nippon Kasei Co., Ltd., “TAIC”] 10 parts, RAFT agent (chain transfer agent, RAFT-NT, manufactured by Nippon Terpene Chemical Co., Ltd.): Bis {4- [ethyl- (2-hydroxyethyl) carbamoyl A solution in which 0.6 part of benzyl} trithiocarbonate was mixed was prepared.
This preparation solution was added from the separatory funnel to the flask maintained at a temperature of about 50 ° C. over 3 hours with stirring to carry out emulsion polymerization. The polymerization was completed after aging for 5 hours to obtain a dispersion (particle 1) of colored resin fine particles for aqueous ink.
The average particle diameter of the colored resin fine particles was 120 nm.

(Production Example 2)
In Production Example 1, the distilled water was 340.5 parts, the amount of cyclohexyl methacrylate monomer was 30 parts, the amount of n-butyl methacrylate was 45 parts, and the dye was an oil-soluble dye [Varifast Pink]. 2310N, manufactured by Orient Chemical Industry Co., Ltd.] 20 parts, oil-soluble dye [Oil Pinink 314, manufactured by Orient Chemical Industry Co., Ltd.] 12 parts, oil-soluble dye [Varifers Red 3312, manufactured by Orient Chemical Industries Co., Ltd.] 12 parts, and RAFT agent (Chain transfer agent): Colored fine particles for aqueous ink as in Production Example 1 except that 0.3 parts of bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate was used. An aqueous dispersion (particle 2) was obtained.
The average particle diameter of the colored resin fine particles was 97 nm.

(Production Example 3)
In Production Example 1, the distilled water was 333.5 parts, the amount of cyclohexyl methacrylate monomer was 60 parts, the amount of n-butyl methacrylate was 30 parts, and the dye was an oil-soluble dye [spiron yellow CGNH New, manufactured by Hodogaya Chemical Co., Ltd.] 25 parts, oil-soluble dye [Varifast Yellow 1109, manufactured by Orient Chemical Industry Co., Ltd.] 11 parts, and RAFT agent (chain transfer agent): bis {4- [ethyl- ( A colored fine particle aqueous dispersion (particle 3) for aqueous ink was obtained in the same manner as in Production Example 1 except that 0.8 part of 2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate was used.
The average particle diameter of the colored resin fine particles was 38 nm.

(Production Example 4)
In Production Example 1 above, distilled water is 309.5 parts, polymerizable surfactant (manufactured by ADEKA, ADEKA rear soap SE-10N, ether sulfate) is 10 parts, and the amount of cyclohexyl methacrylate monomer is 60 parts. The amount of n-butyl methacrylate is 35 parts, and the dyes are oil-soluble dyes (Varifast Red 3312, manufactured by Orient Chemical Co., Ltd.), 10 parts, oil-soluble dyes (Varifast Black 1821, manufactured by Orient Chemical Industries, Ltd.). 25 parts, 10 parts of an oil-soluble dye [Varifast Yellow 129, manufactured by Orient Chemical Co., Ltd.], and RAFT agent (chain transfer agent): bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} tri Coloring for water-based ink in the same manner as in Production Example 1 except that 0.4 parts of thiocarbonate was used. It was obtained particle aqueous dispersion (particle 4).
The average particle diameter of the colored resin fine particles was 46 nm.

(Production Example 5)
In Production Example 1, RAFT agent (chain transfer agent, RAFT-NT, manufactured by Nippon Terpene Chemical Co., Ltd.): 0.6 parts of bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate A colored fine particle aqueous dispersion (particle 5) for aqueous ink was obtained in the same manner as in Production Example 1 except that 0.6 part of bis [4- (allyloxycarbonyl) benzyl] trithiocarbonate was used.
The average particle diameter of the colored resin fine particles was 110 nm.

(Production Example 6)
In Production Example 2, RAFT agent (chain transfer agent, RAFT-NT, manufactured by Nippon Terpene Chemical Co., Ltd.): 0.6 parts of bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate RAFT agent (chain transfer agent): A colored fine particle aqueous dispersion (particle 6) for aqueous ink was obtained in the same manner as in Production Example 2 except that 0.4 part of S, S-dibenzyltrithiocarbonate was used. It was.
The average particle diameter of the colored resin fine particles was 115 nm.

(Production Example 7)
In Production Example 4, RAFT agent (chain transfer agent, RAFT-NT, manufactured by Nippon Terpene Chemical Co., Ltd.): 0.6 parts of bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate A colored fine particle aqueous dispersion (particle 7) for aqueous ink was obtained in the same manner as in Production Example 4 except that the amount was 0.1 parts.
The average particle diameter of the colored resin fine particles was 87 nm.

(Production Example 8)
In Production Example 4, RAFT agent (chain transfer agent, RAFT-NT, manufactured by Nippon Terpene Chemical Co., Ltd.): 0.6 parts of bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate A colored fine particle aqueous dispersion (particle 8) for aqueous ink was obtained in the same manner as in Production Example 1 except that the amount was 2.0 parts.
The average particle diameter of the colored resin fine particles was 90 nm.

(Production Example 9)
In the above Production Example 1, without using the RAFT agent (chain transfer agent): bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate (no amount used), Similarly, a colored fine particle aqueous dispersion (particle 9) for water-based ink was obtained.
The average particle diameter of the colored resin fine particles was 60 nm.

(Production Example 10)
In the above Production Example 2, without using the RAFT agent (chain transfer agent): bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate (no amount used), the above Production Example 2 and Similarly, a colored fine particle aqueous dispersion (particle 10) for water-based ink was obtained.
The average particle diameter of the colored resin fine particles was 70 nm.

(Production Example 11)
In the above Production Example 3, without using the RAFT agent (chain transfer agent): bis {4- [ethyl- (2-hydroxyethyl) carbamoyl] benzyl} trithiocarbonate (no amount used), the above Production Example 3 and Similarly, a colored fine particle aqueous dispersion (particle 11) for water-based ink was obtained.
The average particle diameter of the colored resin fine particles was 83 nm.

  The dispersion of the colored resin fine particles for each water-based ink obtained in Production Examples 1 to 11 had a resin solid content of 20 to 40% by mass.

[Examples 1-8 and Comparative Examples 1-3: Preparation of Aqueous Ink Composition for Writing Instruments]
Using the colored resin fine particle dispersions (particles 1 to 12) produced in Production Examples 1 to 11 above, water-based ink compositions for writing instruments are prepared by a conventional method with the following composition (total amount: 100% by mass). did.
Ink composition: (100% by mass in total)
Dispersion of colored resin fine particles for each water-based ink 50% by mass
pH adjuster (triethanolamine) 1% by mass
Water-soluble organic solvent (ethylene glycol) 5% by mass
Ion-exchanged water 44% by mass

About each obtained water-based ink composition for writing instruments (100 mass% of whole quantity), the sticking property and water-wiping erasability were evaluated with the following evaluation method.
Table 1 below shows the evaluation results of Examples 1 to 8 and Comparative Examples 1 to 3.

[Evaluation test method for adhesion]
A PC-5M pen body made by Mitsubishi Pencil Co., Ltd. is filled with a water-based ink composition for each writing board, and in a 25 ° C. and 65% humidity environment, five spirals with a diameter of about 30 mm, on a black board or white board The board was rubbed once with Kim Towel (laboratory paper towel, Nippon Paper Crecia Co., Ltd.) while keeping the board horizontal. The state of the drawn lines after rubbing was observed and evaluated according to the following evaluation criteria (n = 5).
Evaluation criteria:
A: Even if a force of 19.6 N (weight 2 kg) was applied from above, it could not be erased.
B: A force of more than 9.8 N to less than 19.6 N (weight 2 kg) is applied from above and scratched to erase.
did it.
C: A force of 9.8 N (weight 1 kg) or less was applied from above, and the surface was rubbed and erased.

<Wipe wipe erasability>
A PC-5M pen body made by Mitsubishi Pencil Co., Ltd. is filled with a water-based ink composition for each writing board, and in a 25 ° C. and 65% humidity environment, five spirals with a diameter of about 30 mm, on a black board or white board And about 25 g of tap water was included in a Kim towel (laboratory paper towel, manufactured by Nippon Paper Crecia Co., Ltd.) and rubbed once while keeping the board horizontal. The state of the drawn lines after rubbing was observed and evaluated according to the following evaluation criteria (n = 5).
Evaluation criteria:
A: It was able to erase by applying a force horizontally without placing a weight.
B: A force of 0N to 7.84N (weight 0.8kg) or less is applied from above and scratched to erase.
did it.
C: Erase by applying a force from above 7.84N to 9.8N (weight 1kg) from above
did it.
D: Erase by applying a force from above 9.8N to less than 19.6N (weight 2kg)
did it.
E: Even if a force of 19.6 N (weight 2 kg) was applied from above, it could not be erased.

  Considering Table 1 above, it was found that Examples 1 to 8, which are within the scope of the present invention, are superior in fixing property and water wiping erasability as compared with Comparative Examples 1 to 3, which are outside the scope of the present invention.

  A dispersion of colored resin fine particles for aqueous ink suitable for writing instruments such as sign pens, marking pens and ballpoint pens, and aqueous ink compositions for writing instruments and writing instruments using the same are obtained.

Claims (2)

Colored resin fine particles obtained by living radical polymerization of at least a monomer component and a dye using a RAFT agent, wherein the RAFT agent is selected from dibenzyltrithiocarbonate compounds represented by the following formula (I) Colored resin fine particles characterized by being at least one kind.

[In the formula (I), Ar represents a phenylene group, and R ₁ and R ₂ may be the same or different, and are a hydrogen atom, an acetoxy group, a hydroxy group, a hydroxymethyl group, or the formula: —C (O) —O—CH ₂ —R ₃ (where R ₃ is an alkyl group having 1 to 5 carbon atoms having a hydroxy group at the terminal, and 2 to 2 carbon atoms each having a hydroxy group at the terminal and its adjacent position) 5 represents an alkyl group having 5 to 5 carbon atoms, an alkenyl group having 2 to 5 carbon atoms having a double bond between the terminal and its adjacent position, or an alkyl group having 2 to 5 carbon atoms having an epoxy at the terminal and its adjacent position. Or the formula: —C (O) —N (R ₄ ) — (CH ₂ ) n —R ₅ (where R ₄ is an alkyl group having 1 to 5 carbon atoms, n is a number of 1 to ₅ , R ₅ Represents an acetoxy group or a hydroxy group. ]   An ink composition for a writing instrument, comprising the colored resin fine particles according to claim 1.