Resin particle dispersion and aqueous ink composition containing same

Abstract

The present invention provides: a resin particle dispersion which exhibits excellent waterproof fixing properties and fixing properties to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (finely coated surfaces) and which is suitable for use in an aqueous ink composition for a writing instrument or the like; and an aqueous ink composition containing said resin particle dispersion.　This resin particle dispersion is characterized by: containing at least resin particles and water; the resin particles containing a (meth)acrylic resin; and in that the (meth)acrylic resin contains a unit A represented by a general formula (I) and at least one of a unit B having a phosphoric acid group and / or a phosphoric acid ester group and a unit C having a phosphonic acid group and / or a phosphonic acid ester group.　In addition, the aqueous ink composition is characterized by containing the resin particle dispersion having these features. (In formula (I), A is a hydrogen atom (H) or a methyl group (CH3), and R is a hydrogen atom (H), an alkyl group having 1-22 carbon atoms, or the like.)

Description

Resin particle dispersion and aqueous ink composition containing the same

[0001] The present specification relates to a resin particle dispersion suitable for aqueous ink compositions for writing instruments and the like, which has excellent water-resistant adhesion properties and adhesion to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (lightly coated surfaces), and to an aqueous ink composition containing the same.

[0002]

[0003] Examples of resin particles and the like having excellent adhesion include: 1) metallic and pearlescent ink compositions for use in marking pens and the like, which contain a dispersant-cum-fixing agent, such as an acrylic resin or a styrene-acrylic resin, in an amount of 5 to 30% by weight, based on the total weight of the ink (see, for example, Patent Document 1); 2) a novel phosphate group-containing block copolymer that can highly finely disperse particulate pigments and can be used to prepare a pigment colorant composition having excellent application properties, which is an A-B block copolymer consisting of an A polymer block and a B polymer block containing 90% by weight or more of structural units derived from a methacrylate monomer, and in which only the B polymer block contains structural units derived from a phosphate group-containing methacrylic acid monomer having a phosphate group (see, for example, Patent Document 2); and 3) an aqueous ballpoint pen ink composition that contains at least one specific phosphate ester, such as a polyoxypropylene alkyl ether phosphate monoester and a polyoxypropylene alkyl ether phosphate diester (see, for example, Patent Document 3).

[0003] However, although the resin particles and the like described in the above Patent Documents 1 to 3 have various effects not previously available, they still sometimes have unstable water-resistant adhesion and adhesion to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (lightly coated surfaces), and there has been a strong demand for a resin particle dispersion suitable for aqueous ink compositions and the like that has excellent water-resistant adhesion and adhesion to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (lightly coated surfaces), as well as an aqueous ink composition for writing instruments that contains the same.

[0004] JP-A-5-117569 (claims, examples, etc.) JP-A-2013-103993 (claims, examples, etc.) JP-A-2015-174944 (claims, examples, etc.)

[0005] The present disclosure has been made in view of the above-mentioned problems of the conventional art and attempts to solve them, and aims to provide a resin particle dispersion suitable for aqueous ink compositions for use with writing instruments, on skin, etc., which has excellent water-resistant adhesion properties and adhesion to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (lightly coated surfaces), and an aqueous ink composition containing the same.

[0006] In view of the above-mentioned conventional problems and the like, the present inventors have conducted intensive research and found that the above-mentioned intended resin particle dispersion and the like can be obtained by containing at least resin particles and water, the resin particles containing a (meth)acrylic resin, and the (meth)acrylic resin containing a unit A represented by a specific formula and at least one of a unit B having a phosphoric acid group and / or a phosphoric acid ester group, and a unit C having a phosphonic acid group and / or a phosphonic acid ester group, and have thus completed the present disclosure.

[0007] That is, the resin particle dispersion of the present disclosure contains at least resin particles and water, the resin particles contain a (meth)acrylic resin, and the (meth)acrylic resin contains at least one of a unit A represented by the following general formula (I), a unit B having a phosphoric acid group and / or a phosphoric acid ester group, and a unit C having a phosphonic acid group and / or a phosphonic acid ester group: [In the above formula (I), A represents a hydrogen atom (H) or a methyl group (CH3); R represents a hydrogen atom (H), an alkyl group having 1 to 22 carbon atoms, or a substituent having a polyalkylene glycol chain whose alkylene chain has 2 to 18 carbon atoms; the alkyl group or the substituent having a polyalkylene glycol chain may have, as a substituent, 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.] The content of the unit A is preferably 30 to 97% by mass based on all polymer components constituting the resin particles. The content of the unit B and / or the unit C is preferably 1% by mass or more based on all polymer components constituting the resin particles. The average particle diameter of the resin particles is preferably 10 to 800 nm. The content of the resin particles is preferably 0.1 to 50% by mass based on the total amount of the resin particle dispersion. The aqueous ink composition for a writing instrument according to the present disclosure is characterized by containing the resin particle dispersion having the above-described configuration.

[0008] According to the present disclosure, a resin particle dispersion suitable for aqueous ink compositions, etc., having excellent water-resistant adhesion and adhesion to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (lightly coated surfaces), and an aqueous ink composition containing the same are provided. The objects and advantages of the present disclosure will be realized and attained by using the elements and combinations particularly pointed out in the claims. Both the general description above and the detailed description below are exemplary and explanatory and do not limit the present disclosure as set forth in the claims.

[0009] The following describes in detail the embodiments of the present disclosure. However, it should be noted that the technical scope of the present disclosure is not limited to the embodiments described in detail below, but extends to the inventions set forth in the claims and their equivalents.

[0010] (Resin Particle Dispersion) The resin particle dispersion of the present disclosure contains at least resin particles and water, the resin particles contain a (meth)acrylic resin, and the (meth)acrylic resin contains at least one of a unit A represented by the following general formula (I), a unit B having a phosphoric acid group and / or a phosphoric acid ester group, and a unit monomer C having a phosphonic acid group and / or a phosphonic acid ester group: [In the above formula (I), A represents a hydrogen atom (H) or a methyl group (CH3), and R represents a hydrogen atom (H), an alkyl group having 1 to 22 carbon atoms, or a substituent having a polyalkylene glycol chain in which the alkylene chain has 2 to 18 carbon atoms, and the substituent having the 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.]

[0011] The unit A represented by the above general formula (I) used in the present disclosure is a (meth)acrylic acid ester monomer, and this unit A is selectively used because it can produce stable particles, does not have an adverse effect on other blended components, and has a long-lasting desired effect. R in the above general formula (I) represents a hydrogen atom (H), an alkyl group having 1 to 22 carbon atoms, or a substituent having a polyalkylene glycol chain in which the alkylene chain has 2 to 18 carbon atoms, and the alkyl group or the substituent having a polyalkylene glycol chain may have, as a substituent, 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. Examples thereof include a linear or branched alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 10 carbon atoms, and an alkyl group having 1 to 18 carbon atoms which may have, as a substituent, an epoxy group, a hydroxyl group, a dialkylamino group, or an alkoxy group having 1 to 4 carbon atoms. In particular, an alkyl group having 1 to 6 carbon atoms which may have, as a substituent, an epoxy group, a hydroxyl group, or an alkoxy group having 1 to 2 carbon atoms, and an alkyl group having 1 to 6 carbon atoms which may have, as a substituent, an epoxy group. 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 expression "(meth)acrylic acid" means "acrylic acid and / or methacrylic acid".

[0012] Specific examples of the (meth)acrylic acid ester to be used as the unit A represented by the 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, and benzoyl (meth)acrylate. Dimethylaminoethyl (meth)acrylate, methyl methyl chloride salt of dimethylaminoethyl (meth)acrylate, ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, 1,3-dimethylethyl ...6-Hexanediol, trimethylolpropane tri(meth)acrylate, 2-(meth)acroyloxyethyl phthalate, 2-(meth)acroyloxyethyl 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, 2-(dimethylamino)butyl (meth)acrylate, 2-isocyanoethyl (meth)acrylate, 2-(acetoacetoxy)ethyl (meth)acrylate, perfluoroethyl methacrylate having a perfluoroalkyl group having 1 to 18 carbon atoms, 2-(phosphate)ethyl (meth)acrylate [2-(methacryloyloxy)ethyl phosphate], trialkoxysilylpropyl (meth)acrylate, dialkoxymethylsilylpropyl (meth)acrylate, etc. (each may be used alone or in combination, the same applies hereinafter). Of these, the unit A is 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, or cyclohexyl (meth)acrylate, because they are easily available industrially, are easy and safe to handle during production, and further improve the effects of the present disclosure.

[0013] In the present disclosure, in addition to the (meth)acrylic acid ester that constitutes unit A represented by general formula (I) above, it is preferable to further use a hydrophobic vinyl monomer or aqueous monomer other than the above (meth)acrylic acid ester monomer, in order to obtain a sustained functional effect. As the hydrophobic vinyl monomer, for example, at least one monomer other than the above (meth)acrylic acid ester monomer, such as styrene or methylstyrene, can be used. Usable hydrophobic vinyl monomers include, for example, at least one of styrene, methylstyrene, chloromethylstyrene, alkylstyrene having an alkyl group having 1 to 12 carbon atoms, methoxystyrene, chlorostyrene, bromostyrene, divinylbenzene, phenylstyrene, vinylnaphthalene, and the like. Usable aqueous monomers include, for example, at least one of glycerin monomethacrylate, 2-sulfoethyl sodium 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.

[0014] Next, examples of the unit B having a phosphoric acid group and / or a phosphoric acid ester group used in the present disclosure include mono(2-acryloyloxyethyl) acid phosphate, mono(2-methacryloyloxyethyl) acid phosphate, diphenyl(2-acryloyloxyethyl) phosphate, diphenyl(2-methacryloyloxyethyl) phosphate, phenyl(2-acryloyloxyethyl) phosphate, acid phosphooxyethyl methacrylate, methacryloyl oxyethyl acid phosphate monoethanolamine salt, and 3-chloro-2-acid phosphooxypropyl methacrylate. Examples of suitable units include at least one of acid phosphate, acid phosphooxy polyoxyethylene glycol monomethacrylate, acid phosphooxy polyoxypropylene glycol methacrylate, (meth)acryloyloxyethyl acid phosphate, (meth)acryloyloxypropyl acid phosphate, (meth)acryloyloxy-2-hydroxypropyl acid phosphate, (meth)acryloyloxy-3-hydroxypropyl acid phosphate, (meth)acryloyloxy-3-chloro-2-hydroxypropyl acid phosphate, and allyl alcohol acid phosphate. Among these, acid phosphooxyethyl methacrylate, 2-methacryloyloxyethyl acid phosphate, and phosphorus-containing methacrylic acid esters [{e.g., CH2=C(CH3)-COO(RO)n-P(=O)(OH)2}, R: CH2CH2] are preferred as the unit B, in terms of the ability to produce stable particles and the ability to fully exert the desired effects.

[0015] Examples of the unit C having a phosphonic acid group and / or a phosphonate ester group used in the present disclosure include at least one of vinylphosphonic acid, diethyl vinylphosphonate, diethyl allylphosphonate, vinylidene-1,1-diphosphonic acid, dimethyl-p-vinylbenzyl phosphonate, vinylphosphonic acid, ammonium bisdiethylphosphonate (meth)acrylate, and acrylamide phosphonate monomer. Among these, the use of vinylphosphonic acid is desirable in terms of fully exhibiting the desired effects.

[0016] The resin particle dispersion of the present disclosure is a dispersion in which resin particles constituted of at least the unit A represented by the above-mentioned general formula (I) and at least one of the unit B having a phosphoric acid group and / or a phosphoric acid ester group, and the unit C having a phosphonic acid group and / or a phosphonic acid ester group are dispersed in water. The resin particle dispersion can be produced, for example, by adding a (meth)acrylic acid ester monomer (each of which may be a single monomer or two or more monomers, the same applies hereinafter) which constitutes the unit A, or a mixed monomer containing the above-mentioned (meth)acrylic acid ester monomer and other hydrophobic vinyl monomers and / or aqueous monomers, to a resin particle dispersion. At least one of units B having a phosphonic acid group and / or a phosphoric acid ester group and units C having a phosphonic acid group and / or a phosphonic acid ester group (units B and / or units C) is dissolved, and a polymerization initiator such as ammonium persulfate, potassium persulfate, hydrogen peroxide, or the like is used in combination with a reducing agent. Further, a polymerization initiator such as triallyl isocyanurate, triallyl isocyanurate, polyethylene glycol dimethacrylate, polypropylene glycol dimethacrylate, pentaerythritol acrylate, ditrimethylolpropane acrylate, dipentaerythritol ... crosslinking agents such as tetritol acrylate, methoxylated bisphenol A methacrylate, pentaerythritol methacrylate, ditrimethylolpropane methacrylate, dipentaerythritol methacrylate, and ethoxylated polyglycerin methacrylate, and, if necessary, polyoxyethylene-1-(allyloxymethyl)-alkyl ether ammonium sulfate, ether sulfate, polyoxyethylene nonylpropenyl phenyl ether ammonium sulfate, polyoxyethylene nonylpropenyl phenyl ether, ammonium polyacrylate, styrene-maleic acid copolymer ammonium, polyoxyethylene alkyl ether, polyoxyethylene styrenated phenyl ether, polyoxyethylene polyoxypropylene glycol, polyoxyalkylene decyl ether, polyoxyethylene tridecyl ether, alkylbenzene sulfonate, dioctyl sulfosuccinate, sodium lauryl sulfate, polyoxyethylene alkyl ether phosphate ester, polyoxyethylene styrenated phenyl ether phosphate ester, and polyoxyethylene styrenated phenyl ether sulfate;It can be produced by emulsion polymerization using a polymerizable surfactant (emulsifier) ​​such as polyoxyethylene alkyl ether sulfate, polyoxyethylene sorbitan monolaurate (polysorbate 20), polyoxyethylene sorbitan palmitate (polysorbate 40), polyoxyethylene sorbitan monostearate (polysorbate 60), or polyoxyethylene sorbitan oleate (polysorbate 80), and after being produced as a dispersion of resin particles, it can be dried or the like to form resin particles. The use of a crosslinking agent such as triallyl isocyanurate is preferred because it improves the heat resistance, mechanical properties, hydrolysis resistance, and weather resistance of the resin particle dispersion.

[0017] In the present disclosure, during the emulsion polymerization, an appropriate amount of dicyclopenta(tenyl)(meth)acrylate monomer or the like may be further mixed with the (meth)acrylic acid ester monomer or the like that is the unit A, and the emulsion polymerization may be carried out. When this dicyclopenta(tenyl)(meth)acrylate monomer is further mixed and then emulsion polymerized, stability is less likely to be lost even if water in the dispersion evaporates, and a resin particle dispersion with even better stability can be obtained. Dicyclopenta(tenyl)(meth)acrylate monomers that can be used include dicyclopentanyl acrylate monomer, dicyclopentenyl acrylate, dicyclopentanyl methacrylate monomer, and dicyclopentenyl methacrylate. In the present disclosure, during the emulsion polymerization, in addition to the (meth)acrylic acid ester monomer which is the unit A, the other hydrophobic vinyl monomers, and the dicyclopent(en)yl(meth)acrylate monomer, a monomer having a reactive crosslinking group such as an epoxy group, a hydroxymethylamide group, or an isocyanate group, or a polyfunctional monomer having two or more vinyl groups may be blended in an appropriate amount to cause crosslinking.

[0018] In the present disclosure, the content of the (meth)acrylic acid ester monomer that forms the unit A among the polymer components that constitute the resin particle dispersion is preferably 30% by mass or more, more preferably 30 to 97% by mass, and particularly preferably 30 to 70% by mass, relative to the total polymer components that constitute the resin particle dispersion. In the present disclosure, the term "total polymer components" refers to the polymerizable components that constitute the resin particle dispersion, specifically the total amount of the unit A, unit B, and / or unit C, and the crosslinking agent used. By ensuring that the content of the unit A represented by the general formula (I) is 30% by mass or more relative to the total polymer components, the effects of the present disclosure can be more efficiently exhibited without impairing stability over time.

[0019] Furthermore, the content of the unit B and / or the unit C is preferably 1% by mass or more, more preferably 3 to 30% by mass, and particularly preferably 5 to 20% by mass, relative to the total polymer components constituting the resin particles, from the viewpoint of further exhibiting the effects of the present disclosure, dispersibility, reactivity, and the like.

[0020] The polymerizable surfactant that can be used as needed is not particularly limited as long as it is a polymerizable surfactant commonly used in the emulsion polymerization. For example, the polymerizable surfactant may be an anionic or nonionic polymerizable surfactant, such as Adeka Reasoap NE-10, NE-20, NE-30, NE-40, or SE-10N manufactured by Adeka Corporation; Latemul S-180, S-180A, or S-120A manufactured by Kao Corporation; Eleminol JS-20 manufactured by Sanyo Chemical Industries, Ltd.; or Aqualon KH-10 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. 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 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 monomers.

[0021] In the present disclosure, a resin particle dispersion (liquid dispersion) in which resin particles are dispersed in water can be obtained by dissolving at least one of the above-mentioned unit B having a phosphoric acid group and / or a phosphoric acid ester group and / or the unit C having a phosphonic acid group and / or a phosphonic acid ester group in a (meth)acrylic acid ester monomer that becomes at least the unit A represented by the above-mentioned general formula (I) and emulsion-polymerizing the resulting solution, or by polymerizing a mixed monomer containing at least the above-mentioned unit A and other monomer components and then dissolving at least one of the above-mentioned unit B having a phosphoric acid group and / or a phosphoric acid ester group and / or the unit C having a phosphonic acid group and / or a phosphonic acid ester group and emulsion-polymerizing the resulting solution.

[0022] The amount of resin particles in the resin particle dispersion obtained under these production conditions varies depending on the blending amounts of the (meth)acrylic acid ester monomer (unit A), unit B, and / or unit C, etc., used, the polymerization conditions, etc. From the viewpoints of manufacturability, workability, efficiency, etc., it is preferable to produce the resin particle dispersion so that the solid content is 1 to 50 mass %. It is even more preferable to produce the resin particle dispersion so that the solid content is 10 to 40 mass %. This resin particle dispersion (liquid dispersion) has strong and durable fixing performance without adversely affecting other components, etc., and is suitable for aqueous ink compositions for writing instruments, etc., which have excellent water-resistant fixing properties and excellent fixing properties to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (lightly coated surfaces), and is also a resin particle dispersion with excellent stability. In particular, a resin particle dispersion can be obtained that can maintain or improve the effects (water-resistant adhesion, adhesion to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (lightly coated surfaces)) of the units B having a phosphate group and / or a phosphate ester group and the units C having a phosphonic acid group and / or a phosphonic acid ester group even after long-term aging. In order to adjust the contents of the units A, B, and C to the above-mentioned specific blending ratios relative to the total polymer components, the types and blending amounts of the polymer components used as well as the stirring conditions, such as the stirring speed, stirring time, and temperature, can be adjusted.

[0023] In addition, in the present disclosure, the average particle size of the resin particles in the resulting resin particle dispersion will vary depending on the type of monomer used (meth)acrylic acid ester monomer (unit A), unit B, and unit C, the content of each of these monomers, the polymerization conditions during polymerization, etc., but is preferably 10 to 800 nm, more preferably 20 to 300 nm, and even more preferably 30 to 200 nm. By setting the average particle size within the above preferred range, the resin particles will have excellent storage stability and will be suitable for the various applications described below. When used in aqueous ink compositions for writing instruments or skin applications, the resin particles will not clog the cores of writing instruments such as felt-tip pens, marking pens, and ballpoint pens, or the applicator body of applicators, and will have excellent storage stability. In order to control the average particle size of the resin particles of the present disclosure within the specific range, the type and amount of the polymer components used can be adjusted, as well as stirring conditions such as stirring speed, stirring time, and temperature. The "average particle size" defined in the present disclosure is a histogram average particle size based on scattered light intensity distribution, and in the present disclosure (including the examples described later), it is the value D50 measured using a particle size distribution measuring device [FPAR1000 (manufactured by Otsuka Electronics Co., Ltd.)].

[0024] In the resin particle dispersion of the present disclosure, the content of the resin particles contained in the dispersion is preferably 0.1 to 50 mass % in terms of solid content, and more preferably 1 to 30 mass % depending on the intended use, etc., as described below. If the content of the resin particles is less than 0.1 mass % in terms of solid content, the effects of the present disclosure cannot be exhibited, whereas if it exceeds 50 mass %, the long-term storage stability is likely to decrease.

[0025] The resin particle dispersion of the present disclosure configured as described above can be used in various products, such as aqueous ink compositions for writing instruments, inkjet printers, etc. Hereinafter, the case where the resin particle dispersion of the present disclosure is used as an aqueous ink composition for a writing instrument will be described.

[0026] The aqueous ink composition for a writing instrument according to the present disclosure is characterized by containing at least the resin particle dispersion having the above-described configuration, and may contain a colorant and a water-soluble organic solvent in addition to the resin particle dispersion. From the viewpoints of exhibiting the effects of the present disclosure without impairing writing performance and of storage stability, the content of the resin particles in the ink composition is preferably 0.1 to 30.0 mass %, more preferably 1.0 to 15.0 mass %, in terms of solid content, relative to the total amount of the ink composition.

[0027] Usable colorants (coloring materials) include water-soluble dyes and pigments, such as inorganic pigments, organic pigments, and plastic pigments. Hollow resin particles with voids inside them can also be used as white pigments. Alternatively, colored resin particles (pseudo-pigments) dyed with dyes that have excellent color development and dispersibility can also be used. Thermochromic pigments and photochromic pigments can also be used. As water-soluble dyes, direct dyes, acid dyes, food dyes, and basic dyes can all be used in appropriate amounts within a range that does not impair the effects of the present disclosure. The content of these colorants varies depending on the type of writing instrument, but is generally 1 to 30% by mass of the total ink composition.

[0028] Examples of usable water-soluble organic solvents include ethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, 1,2-butanediol, 2,3-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2,5-hexanediol, 3-methyl-1,3-butanediol, and 2-methylpentane. alkylene glycols such as 1,2,4-diol, 3-methylpentane-1,3,5-triol, and 1,2,3-hexanetriol; polyalkylene glycols such as polyethylene glycol and polypropylene glycol; glycerols such as glycerol, diglycerol, and triglycerol; lower alkyl ethers of glycols such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, and diethylene glycol mono-n-butyl ether; N-methyl-2-pyrrolidone; and 1,3-dimethyl-2-imidalidinone.

[0029] Other water-soluble solvents that can be mixed include 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, and benzyl alcohol, amides such as dimethylformamide and diethylacetamide, and ketones such as acetone. The content of these water-soluble organic solvents varies depending on the type of writing implement, such as a felt-tip pen, marking pen, or ballpoint pen, and is particularly effective in an ink composition with a content of 1 to 40% by mass, and 10% by mass or less, based on the total amount of the ink composition, from the viewpoint of further improving the drying properties of drawn lines, and more preferably 3 to 8% by mass.

[0030] The aqueous ink composition for a writing instrument of the present disclosure may contain, in addition to the resin particles, colorant, and water-soluble solvent having the above-described properties, water (tap water, purified water, distilled water, ion-exchanged water, pure water, etc.) as the solvent as the remainder, as well as dispersants, lubricants, pH adjusters, rust inhibitors, thickeners, evaporation inhibitors, surfactants, and the like, as appropriate, within limits that do not impair the effects of the present disclosure.

[0031] Usable dispersants include nonionic and anionic surfactants and water-soluble resins. Preferably, water-soluble polymers are used. Examples of lubricants include nonionic lubricants such as polyhydric alcohol fatty acid esters, sugar higher fatty acid esters, polyoxyalkylene higher fatty acid esters, and alkyl phosphate esters, which are also used as surface treatment agents for pigments; anionic lubricants such as alkyl sulfonates and alkyl aryl sulfonates of higher fatty acid amides; polyalkylene glycol derivatives, fluorine-based surfactants, and polyether-modified silicones.

[0032] Examples of pH adjusters include ammonia, urea, monoethanolamine, diethanolamine, triethanolamine, alkali metal salts of carbonate or phosphate such as sodium tripolyphosphate and sodium carbonate, and alkali metal hydrates such as sodium hydroxide. Examples of rust inhibitors include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, and saponins. Examples of thickeners include carboxymethylcellulose (CMC) or its salts, fermented cellulose, crystalline cellulose, and polysaccharides. Examples of polysaccharides that can be used include xanthan gum, guar gum, hydroxypropylated guar gum, casein, gum arabic, gelatin, amylose, agarose, agaropectin, arabinan, curdlan, callose, carboxymethyl starch, chitin, chitosan, quince seed, glucomannan, gellan gum, tamarind seed gum, dextran, nigeran, hyaluronic acid, pustulan, funoran, HM pectin, porphyran, laminaran, lichenan, carrageenan, alginic acid, tragacanth gum, alkaloid gum, succinoglycan, locust bean gum, and tara gum. These may be used alone or in combination. Furthermore, commercially available products of these may be used. Examples of evaporation inhibitors include pentaerythritol, p-xylene glycol, trimethylolpropane, triethylolpropane, and dextrin. Examples of surfactants include fluorine-based, silicone-based, and acetylene glycol-based surfactants.

[0033] The aqueous ink composition for a writing instrument of the present disclosure can be prepared by appropriately combining the resin particle dispersion having the above-described properties, the water-soluble solvent, and other components depending on the intended use of the ink for the writing instrument (for a ballpoint pen, a marking pen, etc.), stirring and mixing them using a stirrer such as a homomixer, a homogenizer, or a disper, and then, if necessary, removing coarse particles from the ink composition by filtration or centrifugation.

[0034] Furthermore, the pH (25°C) of the aqueous ink composition for a writing instrument of the present disclosure is preferably adjusted to 5 to 10 using a pH adjuster or the like, from the viewpoints of usability, safety, the stability of the ink itself, and compatibility with the ink container, and more preferably 6 to 9.5.

[0035] The aqueous ink composition for writing instruments of the present disclosure is mounted in ballpoint pens, marking pens, and the like, equipped with a pen tip such as a ballpoint pen tip, fiber tip, felt tip, or plastic tip. Examples of ballpoint pens include those in which the aqueous ink composition for writing instruments having the above-described composition is accommodated in a ballpoint pen ink reservoir (refill) equipped with a ball having a diameter of 0.18 to 2.0 mm, and in which a substance that is incompatible with the aqueous ink composition accommodated in the ink reservoir and has a low specific gravity relative to the aqueous ink composition, such as polybutene, silicone oil, or mineral oil, is accommodated as an ink follower. The structure of the ballpoint pen or marking pen is not particularly limited, and may be, for example, a direct-fill ballpoint pen or marking pen equipped with a collector structure (ink retention mechanism) in which the barrel itself serves as the ink reservoir and is filled with the aqueous ink composition for writing instruments having the above-described configuration.

[0036] In the aqueous ink composition for a writing instrument of the present disclosure, the resin particle dispersion having the above-described properties is incorporated into the aqueous ink composition for a writing instrument, and therefore the composition has water-resistant adhesion and strong and durable adhesion to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (lightly coated surfaces) without adversely affecting other components, etc., and therefore the sustained effect can be maintained for a long period of time. Moreover, since these particles do not impair storage stability or writing performance, the degree of freedom in ink design can be further increased, resulting in an aqueous ink composition for a writing instrument that is suitable for writing instruments such as ballpoint pens and marking pens. The above describes the use of the resin particle dispersion of the present disclosure in an aqueous ink composition for a writing instrument, but the resin particle dispersion of the present disclosure has excellent adhesion effect and stability even after long-term aging. By selecting the units B and C to be used, it is possible to use those that have additional functions, without adversely affecting other components, etc., and at a suitable blending ratio for exhibiting the above-described properties.

[0037] Next, the present disclosure will be described in more detail with reference to Production Examples, Examples, and Comparative Examples, but the present disclosure is not limited to the following Examples, etc.

[0038] [Production Examples 1 to 8: Production of Resin Particle Dispersions (Particles 1 to 8)] Each resin particle dispersion was produced according to the following Production Examples 1 to 8. Note that the "parts" below represent parts by mass, and the resin component is the solid content.

[0039] Production Example 1 A 2-liter flask was equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen gas inlet tube, and a 1000 ml separatory funnel for introducing monomers, and placed in a warm water bath. 1 part of glycerin monomethacrylate (Blenmar GLM, manufactured by NOF Corporation), 1 part of 2-sulfoethyl sodium methacrylate (acrylic ester SEM-Na, manufactured by Mitsubishi Chemical Corporation), 2.0 parts of a polymerizable surfactant (Aqualon KH-10, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), 0.6 parts of a polymerization initiator (ammonium persulfate, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and 72.4 parts of water were then charged, and the internal temperature was raised to 50° C. while introducing nitrogen gas. Separately, a solution was prepared by mixing 22.0 parts of methyl methacrylate (Acryester M, manufactured by Mitsubishi Chemical Corporation) as unit A-1 and 3.0 parts of 2-methacryloxyethyl acid phosphate (Lightester P-1M, manufactured by Kyoeisha Chemical Co., Ltd.) as unit B-1 with 10 parts of a crosslinking agent (triallyl isocyanurate, manufactured by Nippon Kasei Chemical Co., Ltd., TAIC). This prepared solution was added from the separatory funnel to the flask maintained at a temperature of approximately 50°C over a period of 3 hours with stirring, and emulsion polymerization was carried out. The mixture was further aged for 4 hours to terminate the polymerization, yielding a resin particle dispersion (dispersion) (particle 1). The content of the unit A-1 was 78% by mass, based on the total polymer components constituting the resin particles, and the content of the unit B-1 was 10% by mass, based on the total polymer components. The average particle diameter of the resin particles was 64 nm.

[0040] (Production Example 2) A resin particle dispersion (dispersion) (particles 2) was obtained in the same manner as in Production Example 1, except that 3.0 parts of 2-acryloxyethyl acid phosphate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as unit B-2 instead of 2-methacryloxyethyl acid phosphate as unit B-1. The content of unit A-1 was 78% by mass, based on all polymer components constituting the resin particles, and the content of unit B-2 was 10% by mass, based on all polymer components. The average particle diameter of the resin particles was 73 nm.

[0041] (Production Example 3) A resin particle dispersion (dispersion) (particles 3) was obtained in the same manner as in Production Example 1, except that 22.0 parts of cyclohexyl methacrylate (Acryester CH, manufactured by Mitsubishi Chemical Corporation) was used as units A-2 instead of methyl methacrylate as units A-1. The content of units A-1 was 78% by mass, based on all polymer components constituting the resin particles, and the content of units B-1 was 10% by mass, based on all polymer components. The average particle diameter of the resin particles was 80 nm.

[0042] (Production Example 4) A resin particle dispersion (dispersion) (particles 4) was obtained in the same manner as in Production Example 2, except that 22.0 parts of cyclohexyl methacrylate (Acryester CH, manufactured by Mitsubishi Chemical Corporation) was used as units A-2 instead of methyl methacrylate as units A-1. The content of units A-2 was 78% by mass, based on all polymer components constituting the resin particles, and the content of units B-2 was 10% by mass, based on all polymer components. The average particle diameter of the resin particles was 75 nm.

[0043] (Production Example 5) A resin particle dispersion (dispersion) (particles 5) was obtained in the same manner as in Production Example 1, except that 3.0 parts of vinylphosphonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as unit C instead of 2-methacryloyloxyethyl acid phosphate as unit B-1. The content of unit A-1 was 78% by mass, based on all polymer components constituting the resin particles, and the content of unit C was 10% by mass, based on all polymer components. The average particle diameter of the resin particles was 82 nm.

[0044] (Production Example 6) In the same manner as in Production Example 1, 1.5 parts of vinylphosphonic acid (manufactured by Tokyo Chemical Industry Co., Ltd.) as unit C and 1.5 parts of 2-methacryloyloxyethyl acid phosphate (Light Ester P-1M, manufactured by Kyoeisha Chemical Co., Ltd.) as unit B-1 were further used to obtain a resin particle dispersion (dispersion liquid) (particles 6). The content of the unit A-1 was 78% by mass, based on all polymer components constituting the resin particles, the content of the unit B-1 was 5.0% by mass, and the content of the unit C was 5.0% by mass, based on all polymer components. The average particle diameter of the resin particles was 76 nm.

[0045] (Production Example 7) In the same manner as in Production Example 1, the unit B-1 was not used, and 25.0 parts of methyl methacrylate having the unit A-1 (Acryester M, manufactured by Mitsubishi Chemical Corporation) was used to obtain a resin particle dispersion (dispersion liquid) (particles 7). The content of the unit A-1 was 88% by mass based on the total polymer components constituting the resin particles. The average particle diameter of the resin particles was 65 nm.

[0046] (Production Example 8) In the same manner as in Production Example 3, the unit B-1 was not used, and 25.0 parts of cyclohexyl methacrylate (Acryester CH, manufactured by Mitsubishi Chemical Corporation) of the unit A-2 was used to obtain a resin particle dispersion (dispersion liquid) (particles 8). The content of the unit A-2 was 88% by mass based on the total polymer components constituting the resin particles. The average particle diameter of the resin particles was 80 nm.

[0047] The storage stability of each of the resin particle dispersions obtained in Production Examples 1 to 8 was evaluated by the following evaluation method. Each of the resin particle dispersions (dispersions) obtained in Production Examples 1 to 8 was used. The solid content of the resin particles in each of the resin particle dispersions obtained in Production Examples 1 to 8 was 23 to 30% by mass. The results are shown in Table 1 below.

[0048] (Method for evaluating storage stability of resin particle dispersions) Using the resin particle dispersions (liquid dispersions) of Production Examples 1 to 8 obtained above, 50 ml of each resin particle aqueous dispersion obtained was filled into a 100 ml highly transparent PP plastic bottle with a lid, sealed, and stored with the cap facing up at 40°C for 1 month, and then the storage stability was evaluated according to the following evaluation criteria. Evaluation criteria: A: No separation of the dispersion was observed, and there was no sediment at the bottom, so it was good. B: Some separation was observed in the dispersion, and a small amount of sediment could be seen at the bottom. C: Significant separation was observed in the dispersion, and a lot of sediment could be seen at the bottom.

[0049]

[0050] Considering Table 1 above, it was found that Production Examples 1 to 6, which fall within the scope of the present disclosure, have superior storage stability compared to Production Examples 7 and 8, which fall outside the scope of the present disclosure.

[0051] [Examples 1 to 14 and Comparative Examples 1 to 8: Preparation of Aqueous Ink Compositions] Each aqueous ink composition was prepared by a conventional method according to the formulation (total amount 100% by mass) shown in Table 2 below, using the resin particle dispersions obtained in Production Examples 1 to 6 above for Examples 1 to 14, the resin particle dispersions obtained in Production Examples 7 and 8 above for Comparative Examples 1, 2, 5, and 6, compositions containing no resin particles for Comparative Examples 3 and 7, and compositions containing no resin particles but a binder (acrylic acid resin) for Comparative Examples 4 and 8. The contents of each resin particle and binder in Table 2 are expressed in terms of solid content.

[0052] Using each of the obtained aqueous ink compositions (total amount 100% by mass), writing instruments (signtip pens, ballpoint pens) having the following configurations were prepared, and the water-resistant adhesion (lightly coated paper, stainless steel) and marker resistance (lightly coated paper, stainless steel) of each aqueous ink composition were evaluated using the following evaluation methods. The evaluation results for Examples 1 to 14 and Comparative Examples 1 to 8 are shown in Table 2 below.

[0053] (Preparation of felt-tip pens) Felt-tip pens were prepared using each of the ink compositions obtained above. Specifically, a felt-tip pen barrel (product name: PM-120T) manufactured by Mitsubishi Pencil Co., Ltd. was used, and the barrel material of this felt-tip pen was recycled PP resin, and the pen core (two types) was made of (fine) PET fiber and (ultrafine) POM resin, and each ink composition was loaded into the felt-tip pen body to prepare the felt-tip pens. In Table 2 below, examples and comparative examples in the form of felt-tip pens are represented as writing implement form "1" (Examples 1 to 7 and Comparative Examples 1 to 4).

[0054] (Preparation of Ballpoint Pens) Ballpoint pens were prepared using each of the ink compositions obtained above. Specifically, each ink composition was loaded into a ballpoint pen body (trade name: UM-153, manufactured by Mitsubishi Pencil Co., Ltd.) to prepare the ballpoint pens. The barrel material of this ballpoint pen was polycarbonate, the cap material was PET resin, the ink reservoir tube was cylindrical, had an inner diameter of 4.0 mm, was made of polypropylene, was 11 mm long, and had a ball diameter of 1.0 mm, and the ball material was cemented carbide. In Table 2 below, examples and comparative examples in the form of ballpoint pens are represented as writing implement form "2" (Examples 8 to 14 and Comparative Examples 5 to 8).

[0055] [Method for evaluating water-resistant adhesion (lightly coated paper, stainless steel)] Using the writing implement (felt pen or ballpoint pen) configured as described above, a 5-layer, 15 mm-wide spiral was drawn on lightly coated paper and a stainless steel plate in an environment of 25°C temperature and 65% humidity. Tap water was sprayed from the nozzle of a commercially available shower at a flow rate of 12 liters per minute for 30 seconds, and the state of the drawn line was observed thereafter and evaluated according to the following evaluation criteria (n=10). Evaluation criteria: A: No change in the drawn line was observed. B: The hue of the drawn line was slightly lighter or part of the drawn line was missing. C: The hue of the drawn line was significantly lighter or half or most of the drawn line was erased. D: The hue and part of the shape of the drawn line remained, but it was difficult to imagine the original shape. E: The drawn line was completely washed away.

[0056] [Method for evaluating marker resistance (lightly coated paper, stainless steel)] Using the writing implement (sign pen or ballpoint pen) configured as described above, a spiral was handwritten on the surface of lightly coated paper and a stainless steel plate in an environment of 25°C and 65% humidity, and then left to dry for 30 minutes. The handwriting thus created was rubbed 20 times with a cotton swab impregnated with a 50% aqueous ethanol solution. The remaining state of the handwriting was visually inspected and evaluated according to the following criteria. Evaluation criteria: A: No bleeding occurred in the handwriting. B: A small part of the handwriting bled slightly. C: Part of the handwriting bled. D: The handwriting was clearly bled.

[0057]

[0058] Unit A-1, unit A-2, unit B-1, unit B-2, unit C, and *1 to *4 in Table 2 above are as follows: Unit A-1: ​​Methyl methacrylate Unit A-2: Cyclohexyl methacrylate Unit B-1: 2-Methacryloyloxyethyl acid phosphate Unit B-2: 2-Acryloyloxyethyl acid phosphate Unit C: Vinylphosphonic acid *1: MCF-88 manufactured by Mitsubishi Chemical Corporation *2: NKW3207E manufactured by Nippon Fluorescent Co., Ltd. *3: Polyoxyethylene distyrenated phenyl ether manufactured by Kao Corporation *4: WATERSOL AC 7514 manufactured by DIC Corporation

[0059] Considering Table 2 above, it was confirmed that the felt-tip pens using the ink compositions of Examples 1 to 7, which are within the scope of the present disclosure, and the ballpoint pens using the ink compositions of Examples 8 to 14, which are within the scope of the present disclosure, are superior in water-resistant adhesion (lightly coated paper, stainless steel) and marker resistance (lightly coated paper, stainless steel) compared to the felt-tip pens using the ink compositions of Comparative Examples 1 to 4 and the ballpoint pens using the ink compositions of Comparative Examples 5 to 8, which are outside the scope of the present disclosure.

[0060] The resin particle dispersion of the present disclosure exhibits excellent water-resistant adhesion properties and adhesion to non-absorbent surfaces (metal surfaces) and poorly absorbent surfaces (lightly coated surfaces), and can therefore be suitably used in aqueous ink compositions for writing instruments, etc.

Claims

1. A resin particle dispersion comprising at least resin particles and water, the resin particles comprising a (meth)acrylic resin, the (meth)acrylic resin comprising at least one of a unit A represented by the following general formula (I), a unit B having a phosphoric acid group and / or a phosphoric acid ester group, and a unit C having a phosphonic acid group and / or a phosphonic acid ester group: [In the above formula (I), A is a hydrogen atom (H) or a methyl group (CH3), and R represents a hydrogen atom (H), an alkyl group having 1 to 22 carbon atoms, or a substituent having a polyalkylene glycol chain in which the alkylene chain has 2 to 18 carbon atoms, and the alkyl group or the substituent having a polyalkylene glycol chain may have, as a substituent, 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.] 2. The resin particle dispersion according to claim 1, wherein the content of the unit A is 30 to 97% by mass based on the total polymer components constituting the resin particles.

3. A resin particle dispersion according to claim 1 or 2, characterized in that the content of the unit B and / or the unit C is 1 mass % or more based on the total polymer components constituting the resin particles.

4. The resin particle dispersion according to claim 1 or 2, characterized in that the average particle diameter of the resin particles is 10 to 800 nm.

5. The resin particle dispersion according to claim 1 or 2, wherein the content of the resin particles is 0.1 to 50% by mass based on the total amount of the resin particle dispersion.

6. An aqueous ink composition comprising the resin particle dispersion according to claim 1 or 2.

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