JP7062403B2 - Gel-like composition, water-based ink composition for writing tools using it, and writing tools using it - Google Patents

Description

The present invention relates to a gelled composition. The present invention also relates to a water-based ink composition for writing tools using a gel-like composition and a writing tool using the same.

Conventionally, a gel-like composition using a crosslinked acrylic acid polymer or the like is known (for example, Patent Document 1). Since these gel-like compositions can handle liquids as if they were solids, they can be used in detergents, sanitary products, toiletry products, personal care products, healthcare products, cosmetics, medical products, pharmaceuticals, agricultural products, electrodes, batteries, etc. It is used.

However, when it is treated as a gel-like composition, it may be necessary to add a large amount in order to increase the viscosity, which causes problems such as poor storage stability.

Further, since it has shear thinning property, it is used in water-based ink compositions for writing and the like. (For example, Patent Documents 2 to 4).
This type of ink has a high viscosity when it is left to stand without shear stress, and is stably held in the mechanism. When it is sheared, it is highly sheared by a ball that rotates at high speed during writing. The force reduces the viscosity of the ink in the vicinity of the ball, and as a result, the ink is ejected from the gap between the ball and the ball accommodating portion and transferred to the paper surface. Since the ink transferred to the paper surface is released from the shearing force, the ink becomes highly viscous again, and it is possible to improve the occurrence of handwriting bleeding, which is a drawback of the conventional water-based ink composition, but it is not sufficient. .. Further, due to the above-mentioned shear reducing viscosity, the so-called batting for holding the ink is not required, the ink can be used to the end, and the ink flow rate adjusting member for adjusting the ink flow rate (for example, the ink temporary member such as a comb-shaped member) is temporarily used. Since it does not require a reservoir member), it has many advantages such as a writing tool having a simple structure, and is therefore widely applied.

However, when a crosslinked acrylic acid polymer conventionally known as a shear reducing viscosity imparting agent is used, the ink viscosity at the time of standing can be increased because the crosslinked portion is chemically bonded, but the shearing is caused by the influence of the crosslinked portion. Since the ink viscosity cannot be lowered below a certain value when cross-linking is applied, there are problems such as blurring of the writing marks and so-called line cracking in which the writing marks are hollow when the writing instrument is used as a water-based writing ink composition. Had.

Japanese Unexamined Patent Publication No. 4-114015 Japanese Unexamined Patent Publication No. 2000-136340 Japanese Unexamined Patent Publication No. 2001-64559 Japanese Unexamined Patent Publication No. 2002-294132

INDUSTRIAL APPLICABILITY The present invention can exhibit good performance when used in a gel-like composition having high thickening and high shear de-viscosity and a writing tool, and handwriting is less likely to bleed even when writing, and the handwriting is not easily blurred or lined. It is an object of the present invention to provide a water-based ink composition for writing tools, which can obtain good handwriting without causing cracks and has excellent storage stability of the ink composition, and a writing tool using the same.

（式中Ｒ_１、水素またはメチル基）

（式中Ｒ_２は、水素またはメチル基、Ｒ_３は、炭素数１～５の直鎖または側鎖を有するアルキル基）
２．前記架橋剤が、前記共重合体とファンデルワールスによる分子間凝集力を発現できる化合物である第１項に記載のゲル状組成物。
３．第１項または第２項に記載のゲル状組成物と着色剤を含んでなる筆記具用水性インキ組成物。
４．第３項に記載の筆記具用水性インキ組成物を具備してなる筆記具。」に関する。 As a result of diligent studies to solve the above problems, the present inventor has made a gel-like composition containing water, a copolymer obtained by copolymerizing a specific monomer, and a cross-linking agent. It was found that the problem could be solved, and the present invention was completed.
That is, the present invention
"1. A gel-like composition containing water, a copolymer obtained by copolymerizing a monomer represented by the following general formula (1) and a monomer represented by the following general formula (2), and a cross-linking agent. ..

(R ₁ , hydrogen or methyl group in the formula)

(In the formula, R ₂ is a hydrogen or methyl group, and R ₃ is an alkyl group having a linear or side chain having 1 to 5 carbon atoms).
2. 2. The gel-like composition according to Item 1, wherein the cross-linking agent is a compound capable of exhibiting an intermolecular cohesive force due to the copolymer and van der Waals.
3. 3. A water-based ink composition for writing tools comprising the gel-like composition according to the first or second paragraph and a colorant.
4. A writing tool comprising the water-based ink composition for writing tools according to item 3. About.

According to the present invention, a specific cross-linking is performed using a copolymer obtained by copolymerizing a monomer represented by the general formula (1) having a specific structure and a monomer represented by the general formula (2). By using the agent, a gel-like composition showing high viscosity can be obtained. Further, the gel-like composition in the present invention can maintain a high viscosity when left to stand, and when a shear stress is applied, the viscosity of the gel-like composition decreases as compared with the conventional case, resulting in a high TI value. A gelled composition having can be obtained. Further, by using the gel-like composition as an ink composition for writing tools, it is possible to maintain good handwriting without blurring or line cracking. In addition, the alkyl group forms a reversible physical bond due to the intermolecular force, and the cross-linking agent and the copolymer exhibit the intermolecular cohesive force due to van der Waals, so that the ink viscosity at rest can be increased. It has excellent effects such as less bleeding of brush marks and improved storage stability of ink.

<Gel-like composition>
The gel-like composition according to the present invention contains water, a copolymer obtained by copolymerizing the monomer represented by the general formula (1) and the monomer represented by the general formula (2), and a cross-linking agent. It consists of.

（式中Ｒ_１、水素またはメチル基）

（式中Ｒ_２は、水素またはメチル基、Ｒ_３は、炭素数１～５の直鎖または側鎖を有するアルキル基） The gel-like composition according to the present invention comprises a copolymer obtained by copolymerizing a monomer represented by the following general formula (1) and a monomer represented by the following general formula (2), and a cross-linking agent.

(R ₁ , hydrogen or methyl group in the formula)

(In the formula, R ₂ is a hydrogen or methyl group, and R ₃ is an alkyl group having a linear or side chain having 1 to 5 carbon atoms).

In the present invention, a copolymer obtained by copolymerizing the monomer represented by the general formula (1) and the monomer represented by the following general formula (2) is used, and the copolymer is a carboxylic acid group. And has a carboxylic acid ester. Since the alkyl group having 1 to 5 carbon atoms of the carboxylic acid ester is a hydrophobic group, the alkyl group is aggregated by the intermolecular force between the hydrophobic groups in the gel-like composition to form a reversible physical bond to form a network. It acts like a formation, or bond point. Therefore, the viscosity at rest becomes high. Then, when shearing is applied, the physical bond of the portion that works like a bond point is dissociated, and the viscosity of the gel-like composition decreases. As described above, the reversible action of aggregation and dissociation of alkyl groups increases the viscosity gradient at rest and when shearing is applied, so that a high thixotropy index value (hereinafter, may be referred to as TI value) is obtained. Can be done. On the other hand, in the conventional cross-linked acrylic acid, since the cross-linking points are chemically bonded, a network is formed and the viscosity at rest becomes high, but the bonding at the cross-linking points is broken even when shearing is applied. Therefore, the viscosity when sheared is increased as compared with the shear reducing viscosity imparting agent used in the present invention. Therefore, the performance as a gel-like composition may be inferior, for example, the TI value may be lower than that of the gel-like composition of the present invention.
By using the gel-like composition according to the present invention, the conventional problems can be solved.

The copolymer obtained by copolymerizing the monomer represented by the general formula (1) and the monomer represented by the following general formula (2) used in the present invention is (meth) acrylic acid- (meth) acrylic acid. It is an ester copolymer. In the present invention, (meth) acrylic means to include both acrylic and methacrylic. Specifically, acrylic acid-acrylic acid ester copolymer, methacrylic acid-acrylic acid ester copolymer, acrylic acid-methacrylic acid ester copolymer, methacrylic acid-methacrylic acid ester copolymer, acrylic acid-methacrylic acid-acrylic acid ester. Acrylic acid-methacrylic acid-methacrylic acid ester copolymer, acrylic acid-acrylic acid ester-methacrylic acid ester copolymer, methacrylic acid-acrylic acid ester-methacrylic acid ester copolymer, acrylic acid-acrylic acid ester -Methacrylic acid-methacrylic acid ester copolymer and the like can be mentioned. As the copolymer used in the present invention, a copolymer such as random, block, etc. can be used. These copolymers can be used alone or in combination of two or more.

Further, R ₃ of the copolymer is an alkyl group having a linear or side chain having 1 to 5 carbon atoms, but when the carbon number is larger than 5, the steric hindrance of the alkyl group becomes large and the alkyl groups aggregate with each other. Power is reduced. Further, when the number of carbon atoms is larger than 5, the hydrophobicity of the alkyl group increases, so that separation or precipitation is likely to occur in a part thereof, which may cause non-uniformity. Therefore, the stability of the gel-like composition tends to be inferior. When the number of carbon atoms is in the range of 1 to 5, the cohesive force between the alkyl groups works high, and physical bonds are formed to form a crosslinked state, which is preferable because a network between molecules is formed. Further, it is preferable that the alkyl group is linear because the steric hindrance is smaller than that of the alkyl group having a side chain. In particular, when R ₃ is a methyl group having 1 carbon atom and an ethyl group having 2 carbon atoms, the hydrophobic force is not large, so that it is possible to design a relatively large amount of the alkyl group introduced into the molecule. By increasing the amount of the alkyl group introduced, it is possible to arrange many physical bond points between the alkyl groups, and it is possible to obtain effects such as higher viscosity at rest and lower viscosity at shear. Especially preferable.

The ratio of the carboxylic acid to the carboxylic acid ester of the copolymer obtained by copolymerizing the monomer represented by the general formula (1) and the monomer represented by the general formula (2) is a molar ratio. It is 1: 0.05 to 1:10, more preferably 1: 0.1 to 1: 5, and even more preferably 1: 0.3 to 1: 3. If the ratio of the carboxylic acid ester is too small, the physical bonding effect of the alkyl group becomes insufficient, and the viscosity gradient at the time of thickening or standing and at the time of shearing tends to be small. Since the hydrophobicity of the polymer is increased, some separation or precipitation may occur. Within this range, both high static viscosity and low shear viscosity can be achieved, which is particularly preferable.

Further, the ratio of the acrylic acid group to the methacrylic acid group of the copolymer obtained by copolymerizing the monomer represented by the general formula (1) and the monomer represented by the general formula (2) is a molar ratio. , 1: 0.1 to 1: 2, more preferably 1: 0.3 to 1: 1. If the ratio of methacrylic acid groups is too large, the hydrophobicity of the copolymer increases, which may cause partial separation or precipitation. Within this range, a high static viscosity and a low shear viscosity can be achieved at the same time, which is particularly preferable.

The amount of the copolymer to be blended can be in the range of 0.01 to 10% by mass with respect to the total mass of the gel-like composition.

<Crosslinking agent>
The gel-like composition according to the present invention uses the copolymer and a cross-linking agent, and the cross-linking agent according to the present invention is a compound capable of forming a physical cross-link with the copolymer, and the same. It is a compound capable of exhibiting intermolecular aggregation by the alkyl group of the polymer ester and van der Waals. When the gel-like composition is in a quiescent state, the cross-linking agent can form a cross-linking point by a physical bond with the alkyl group of the copolymer, and the copolymer and the cross-linking agent can form a strong network. It is a compound in which the physical bond at the cross-linking point is easily broken when a shearing force is applied to the gel-like composition.

In the cross-linking agent, as described above, the alkyl group forms a physical cross-link with the alkyl group of the copolymer, so that the number of cross-linking points is increased and the alkyl of the copolymer is higher than when the copolymer is used alone. Since the effect of complementing the intermolecular distance and the molecular density with respect to the group can be obtained, a stronger network can be formed. Therefore, the gel-like composition containing the copolymer obtained by copolymerizing the monomer represented by the general formula (1) and the monomer represented by the general formula (2) and the cross-linking agent is the same. It exhibits higher viscosity than the gel-like composition in which the polymer is used alone. Further, since the viscosity at the time of standing can be improved and the cross-linking point is a physical cross-linking, when shearing is applied, the respective physical bonds are broken and the viscosity of the gel-like composition is lowered, which is a conventional method. Compared with a shear thinning agent such as crosslinked acrylic acid or a gel-like composition in which the copolymer is used alone, the viscosity is lower, and as a result, the viscosity gradient during standing and shearing is increased. be able to. As described above, since the viscosity at the time of standing can be increased and the viscosity at the time of shearing can be decreased, a high TI value can be obtained.

Specific examples of the cross-linking agent used in the present invention include alkyl-modified glucose, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, alkyl-modified polyethylene oxide, phenyl-modified polyethylene oxide, and phenylalkyl-modified polyethylene oxide. .. The effect can be obtained by using either a high molecular weight compound containing an alkyl group or a low molecular weight compound as the cross-linking agent, but the viscosity at the time of shearing tends to be lower when the low molecular weight compound is used, and the viscosity at the time of standing and shearing tends to be lower. It is preferable because the viscosity gradient at the time can be increased. As the alkyl group, 1 to 30 carbon atoms are used, preferably 1 to 22 and more preferably 1 to 18. In particular, when the number of carbon atoms of the alkyl group is the same, it is preferable to use a compound having less steric hindrance because the effect is enhanced.

The amount of the cross-linking agent to be blended can be in the range of 0.01 to 10% by mass with respect to the total mass of the gel-like composition.

The thixotropy index according to the present invention is measured using an E-type rotational viscometer (DV-II + Pro, cone-type rotor CPA-52Z, manufactured by Brookfield) at 20 ° C. and a shear rate of 1.92 sec-1 and 192 sec-1. It is calculated by the ratio of the viscosities [(viscosity at 1.92 sec-1) / (viscosity at 192 sec-1)].

<Method for producing gel-like composition>
The gelled composition according to the present invention can be produced by any conventionally known method. Specifically, each of the above components can be blended in a required amount and mixed with various stirrers such as a homodisper or a homomixer or various dispersers such as a bead mill for production.

The gel-like composition according to the present invention includes various ink compositions such as writing instrument ink compositions, cleaning agents, sanitary products, toiletry products, personal care products, healthcare products, cosmetics, medical products, pharmaceuticals, agricultural products, electrodes, batteries, etc. Colorants, fragrances, water-soluble organic solvents, pH adjusters, moisturizers, rust preventives, preservatives, thickeners, as long as they do not affect the viscosity or properties of the gel-like composition. Various additives such as agents can be added.

<Aqueous ink composition for writing tools>
As an example of the use of the gel-like composition according to the present invention, it can be used as a water-based ink composition for writing tools (hereinafter, sometimes referred to as "ink composition"). The water-based ink composition for writing tools is a gel-like composition containing a copolymer obtained by copolymerizing the monomer represented by the general formula (1) and the monomer represented by the general formula (2) and a cross-linking agent. And contains a colorant.

As the blending amount of the copolymer, it can be used in the range of 0.01 to 10% by mass with respect to the total mass of the ink composition from the blending ratio of water and the cross-linking agent in the gel-like composition.

The amount of the cross-linking agent to be blended can be in the range of 0.01 to 10% by mass with respect to the total mass of the ink composition from the blending ratio of water and the shear thinning agent in the gel-like composition. ..

<Colorant>
The colorant that can be used in the present invention is not particularly limited, such as dyes and pigments, and can be appropriately selected and used.

The dye that can be used in the present invention is not particularly limited as long as it can be dissolved or dispersed in an aqueous medium. For example, various dyes such as acid dyes, basic dyes, reactive dyes, direct dyes, disperse dyes and food dyes can be mentioned, and these can be used alone or in combination of two or more. The amount of the dye added is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, based on the total mass of the ink composition.

Specifically, as the acid dye, C.I. I. Acid Red 18, C.I. I. Acid Red 51, C.I. I. Acid Red 52, C.I. I. Acid Red 87, C.I. I. Acid Red 92, C.I. I. Acid Red 289, C.I. I. Acid Orange 10, C.I. I. Acid Yellow 3, C.I. I. Acid Yellow 7, C.I. I. Acid Yellow 23, C.I. I. Acid Yellow 42, C.I. I. Acid Green 3, C.I. I. Acid Green 16, C.I. I. Acid Blue 1, C.I. I. Acid Blue 9, C.I. I. Acid Blue 22, C.I. I. Acid Blue 90, C.I. I. Acid Blue 239, C.I. I. Acid Blue 248, C.I. I. Acid Baollet 15, C.I. I. Acid Violet 49, C.I. I. Acid Black 1, C.I. I. Acid Black 2, as a basic dye, C.I. I. Basic Orange 2, C.I. I. Basic Orange 14, C.I. I. Basic Green 4, C.I. I. Basic Blue 9, C.I. I. Basic Blue 26, C.I. I. Basic Violet 1, C.I. I. Basic Violet 3, C.I. I. Basic Violet 10, as a direct dye, C.I. I. Direct Red 28, C.I. I. Direct Yellow 44, C.I. I. Direct Blue 86, C.I. I. Direct Blue 87, C.I. I. Direct Violet 51, C.I. I. Direct Black 19, as an edible dye, C.I. I. Hood Yellow 3, C.I. I. Food black 2 and the like can be mentioned.

Examples of pigments that can be used in the present invention include inorganic, organic, and processed pigments, and specific examples thereof include carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine, and azo. Examples thereof include quinacridone-based, quinophthalone-based, triphenylmethane-based, perinone-based, perylene-based, dioxazine-based, aluminum pigments, pearl pigments, fluorescent pigments, phosphorescent pigments, and complementary color pigments. In addition, microcapsule pigments, liquid crystals, etc., in which a colored body in which a pigment is dispersed in a medium as a colored resin particle body is encapsulated or solid-solubilized in a shell made of a resin wall film forming substance by a known microencapsulation method or the like. A microcapsule pigment containing a functional material such as a reversible thermochromic composition or a photochromic material may be used. Further, colored resin particles in which the pigment is covered with a transparent or translucent resin or the like, or colored resin particles or colorless resin particles colored with a pigment or a dye can also be used. These dyes and pigments may be used alone or in combination of two or more. The content is preferably 1% by mass to 20% by mass with respect to the total amount of the ink composition. As described above, in the present invention, a particularly high effect can be obtained when a pigment is used as a colorant.

<Water>
The water is not particularly limited, and for example, ion-exchanged water, ultrafiltration water, distilled water, or the like can be used.

<Others>
The ink composition according to the present invention is a water-soluble organic solvent, a pH adjuster, a moisturizing agent, a rust inhibitor, a preservative, and a thickener for the purpose of improving the ink properties and functions without impairing the performance of the present invention. It may contain various additives such as.

Examples of the water-soluble organic solvent include (i) glycols such as ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol, or glycerin, and (ii) methanol, ethanol, 1-propanol, 2-propanol, isopropanol, isobutanol, t. -Alcohols such as butanol, propanol alcohol, allyl alcohol, 3-methyl-1-butin-3-ol, ethylene glycol monomethyl ether acetate and other higher alcohols, and (iii) ethylene glycol monomethyl ether, ethylene glycol mono. Examples thereof include glycol ethers such as ethyl ether, 3-methoxybutanol, or 3-methoxy-3-methylbutanol. The amount of the water-soluble organic solvent added is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, based on the ink composition.

Acidity regulators include inorganic salts such as ammonia, sodium carbonate, sodium phosphate, sodium hydroxide, sodium acetate, organic basic compounds such as water-soluble amine compounds such as triethanolamine and diethanolamine, lactic acid and citric acid, etc. Can be mentioned. The amount of the pH adjuster added is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, based on the ink composition.

Examples of the moisturizer include urea, sorbitol, and the like in addition to the water-soluble organic solvent. The amount of the moisturizer added is preferably 0.1 to 10% by mass, more preferably 0.1 to 5% by mass, based on the ink composition.

Examples of the rust preventive include benzotriazole and its derivatives, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, sodium thiosulfate, saponin, dialkylthiourea and the like.

Preservatives include 2-methyl-4-isothiazolin-3-one, 1,2-benzisothiazolin-3-one, 2-n-octyl-4-isothiazolin-3-one, 2-methyl-4,5- Trimethylene-4-isothiazolin-3one, N- (n-butyl) -1,2-benzisothiazolin-3-one, 2-pyridinethiol-1-oxide sodium, 3-iodo-2-propynylbutylcarbamate benzoic acid Examples include sodium, benzotriazole and phenol.

Further, as the water-soluble resin, an acrylic resin, an alkyd resin, a cellulose derivative, polyvinylpyrrolidone, polyvinyl alcohol and the like can be used. Further, as the resin emulsion, an emulsion containing an acrylic resin, a urethane resin, a styrene-butadiene resin, a polyester resin, a vinyl acetate resin and the like can be added.

Further, a fluorine-based surfactant that improves the permeability of the solvent, a nonionic, anionic, cationic surfactant, and a defoaming agent such as dimethylpolysiloxane can be added.

Further, it is preferable to use a lubricant in order to improve the writing quality by smoothing the rotation of the ball by improving the lubricity and to easily suppress the wear of the ball seat. Examples of the lubricant include fatty acids, alkylbenzene sulfonic acids, phosphate esters, amino acids, N-acylamino acids, aliphatic amide alkylene oxide adducts, terpenoid acid derivatives, and salts thereof. More specifically, oleic acid, stearic acid, linoleic acid, linolenic acid, ricinoleic acid, dodecylbenzenesulfonic acid, polyoxyethylene alkyl ether phosphate ester, polyoxyethylene alkyl phenyl ether phosphate ester, alanine, glycine, lysine. , Threonine, serine, proline, sarcosin, N-acylsarkosin, polyoxyethylene fatty acid amides and salts thereof. In particular, it is preferable to use a phosphoric acid ester. This is because the phosphoric acid group adsorbs the metal to further improve the lubricity, improve the writing quality, and facilitate the suppression of wear of the ball seat. Examples of the type of phosphoric acid ester include styrenated phenol-based, nonylphenol-based, lauryl alcohol-based, tridecyl alcohol-based, octylphenol-based, and hexanol-based. Among these, it is preferable to use a phosphate ester-based surfactant that does not have a phenyl skeleton, because having a phenyl skeleton tends to affect the lubricity due to steric hindrance. The lubricant may be used alone or in combination of two or more.

Organic resin particles can be used in the ink composition of the present invention. When organic resin particles are used, the dripping of ink can be suppressed. Examples of the organic resin particles that can be used in the present invention include olefin resin particles such as polyethylene resin and polypropylene resin, melamine / formaldehyde resin, benzoguanamine / formaldehyde resin, benzoguanamine / melamine / formaldehyde resin, urea formaldehyde resin, nylon resin and the like. Examples thereof include nitrogen-containing resin particles containing a nitrogen atom in the chemical structure of the above, acrylic resin particles, styrene resin particles, epoxy resin particles, urethane resin particles, cellulose resin particles and the like. These organic resin particles may be used alone or in combination of two or more.

Among the organic resin particles, it is preferable to use olefin resin particles and nitrogen-containing resin particles. This is because the olefin resin particles are hydrocarbon compounds and are non-polar, so that aggregation is likely to occur in water, and the aggregated structure and the copolymer are entangled with each other to further suppress ink leakage. On the other hand, it is presumed that it is easy to form an optimized aggregate structure that does not cause problems such as insufficient ink ejection amount. Furthermore, since the olefin-based resin particles have a high melting temperature, they tend to exist stably even in a high-temperature environment, and when they are in a high-pressure environment, they are easily deformed and difficult to be denatured. It can be suitably used as an ink additive.

Further, as the nitrogen-containing resin particles, it is preferable to use nitrogen-containing resin particles having a hydrogen-bonding functional group, which is obtained by the hydrogen-bonding functional group structure and the copolymer being entangled with each other. It is presumed that it has an effect of suppressing ink leakage.

Examples of the material of the olefin-based resin particles include polyolefins such as polyethylene, polypropylene, and polybutene, and mixtures thereof. Among these, polyethylene is preferably used in consideration of suppressing ink leakage and improving writing quality, and specifically, low-density polyethylene, high-density polyethylene, low-molecular-weight polyethylene, modified polyethylene, and modified high-density polyethylene. And so on. Among them, low-density polyethylene, low-molecular-weight polyethylene, and modified polyethylene are preferable in consideration of the effect of suppressing ink leakage. In particular, low-density polyethylene has a lower melting point than other types of polyethylene and has a soft property, so that polyethylene particles adhere to it. Low-density polyethylene is preferable because it is easy to make, gaps between particles are hard to occur, and ink is hard to leak. Further, low-density polyethylene is soft and can be suitably used for improving writing quality. The olefin-based resin particles may contain a material other than the polyolefin, if necessary.

Among the nitrogen-containing resin particles, it is preferable to have an amino group or an imino group, because having an amino group or an imino group makes it easy to form a stable aggregated structure for a long period of time and suppress ink leakage. be. The nitrogen-containing resin particles having a functional group of an amino group and an imino group include tertiary amines and quaternary amines.

Further, among the nitrogen resin particles having an amino group or an imino group, it is preferable to use nitrogen-containing resin particles having a chemically bonded three-dimensional crosslinked structure. This is because having a chemically bonded three-dimensional crosslinked structure is particularly excellent in strength, heat resistance, solvent resistance, etc., and is stable without absorbing moisture in water-based ink, so that it is excellent in stability over time. Therefore, it is preferable. Further, due to the stability of the nitrogen-containing resin particles themselves and the mutual hydrogen bondability between the nitrogen-containing resin particles, it is easy to form an aggregated structure for a long period of time, and it is easy to stably suppress ink leakage. In particular, among the nitrogen-containing resin particles having a crosslinked structure, resin particles having a heterocyclic structure such as melamine / formaldehyde resin, benzoguanamine / formaldehyde resin, and benzoguanamine / melamine / formaldehyde resin are more difficult to absorb moisture and are stable. preferable.

Specific examples of the nitrogen-containing resin particles having a crosslinked structure include amino resin particles such as melamine / formaldehyde resin, benzoguanamine / formaldehyde resin, benzoguanamine / melamine / formaldehyde resin, and urea formaldehyde resin. Examples of the nitrogen-containing resin particles having an amide bond include nylon resins such as nylon 6 and nylon 12, polycarbonate-based polyurethane resins, polyether-based polyurethane resins, polyester-based polyurethane resins, urethane resin particles such as urethane urea resins, and the like. Be done.

As the shape of the organic resin particles, spherical or irregularly shaped particles can be used, but spherical resin particles are preferable in consideration of reducing frictional resistance. The spherical resin particles referred to here are not limited to true spheres, and may be substantially spherical resin particles, substantially elliptical spherical resin particles, or the like.

Further, the content of the organic resin particles is more preferably 0.01 to 10.0% by mass with respect to the total amount of the ink composition. This is because if the content of the organic resin particles is less than 0.01% by mass, it is difficult to suppress ink leakage, and if it exceeds 10.0% by mass, the aggregated structure tends to be strong, and the writing quality and dry-up performance are improved. This is because it is easily affected. Further, more consideration is given, preferably 0.02 to 5.0% by mass, particularly preferably 0.03 to 1.0, and most preferably 0.05 to 0.5% by mass.

Further, dextrin can be used in the ink composition of the present invention.
By using dextrin, a film is formed when the ink on the tip of the ballpoint pen dries, so that ink leakage from the gap between the ball and the inner wall of the tip of the tip can be suppressed, or the tip of the pen can be used. The effect of improving the dry-up performance can be obtained. In particular, the combined use of the organic resin particles and dextrin is more effective in suppressing ink leakage.

The weight average molecular weight of the dextrin is more preferably 5000 to 120,000. When the weight average molecular weight of dextrin exceeds 120,000, the film formed on the pen tip is hard, and the handwriting tends to be blurred when writing out during dry-up. On the other hand, when the weight average molecular weight is less than 5,000, the moisture absorption property is high. This is because the height tends to be high, the film formed on the pen tip tends to be soft, and it tends to be difficult to sufficiently obtain the effect of suppressing ink leakage. Further, when the weight average molecular weight is smaller than 20000, the film tends to be thin, and therefore, the weight average molecular weight is particularly preferably 20000 to 120000.

The content of the dextrin in the ink composition is preferably 0.1 to 5% by mass based on the total mass of the ink composition. If it is less than 0.1% by mass, the effect of suppressing ink leakage and improving the dry-up performance of the pen tip tends not to be sufficiently obtained, and if it exceeds 5% by mass, it tends to be difficult to dissolve in the ink. Because. Considering the solubility in ink, it is preferably 0.1 to 3% by mass, and further considering the suppression of ink leakage and the improvement of dry-up performance, it is particularly preferably 1 to 3% by mass. preferable.

Examples of the thickener that can be used in the present invention include an alkaline swelling associated thickener, an associated thickener such as a nonionic associated thickener, and an organic ink viscosity modifier such as a high molecular weight polysaccharide derived from a natural product. These thickeners may be used alone or in combination of two or more. Specific examples of the high molecular weight polysaccharide include xanthan gum, welan gum, succinoglycan, guar gum, locust bean gum, λ-carrageenan, dieutan gum, fermented cellulose, cellulose such as cellulose nanofibers and derivatives thereof. Be done.

The viscosity gradient of the ink composition according to the present invention can be expressed by a viscosity index n at 20 ° C. Here, the viscosity index n refers to n in the viscosity formula represented by S = αD ⁿ . S is a shear stress (dyn / cm2 = 0.1 Pa), D is a shear rate (s ^-1 ), and α is a viscosity coefficient. The viscosity index n can be calculated by measuring the ink viscosity using an E-type rotational viscometer (DV-II + Pro, cone-type rotor CPE-42, manufactured by Brookfield).

<Manufacturing method of ink composition>
The ink composition according to the present invention can be produced by any conventionally known method. Specifically, each of the above components can be blended in a required amount and mixed with various stirrers such as a propeller stirrer, a homodisper, or a homomixer, or various dispersers such as a bead mill to produce the product.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Example 1>
A gel-like composition was obtained by the following compounding composition and method.
Triethanolamine (pH regulator) 1.0% by mass
(Meta) Acrylic Acid-(Meta) Methyl Acrylic Acid Copolymer 0.3% by Mass
(Moral ratio of copolymer carboxylic acid to methyl ester 1: 2.1,
Mole ratio of acrylic acid group to methacrylic acid group 1: 0.36)
Polyoxyethylene Methyl Glucose Triisostearate 0.7% by Mass
(Crosslinking agent)
Ion-exchanged water 98.0% by mass

The gel-like composition of Example 1 was obtained by sufficiently mixing and stirring water, a copolymer, a cross-linking agent, and a pH adjuster using a homogenizer stirrer until a uniform state was obtained. The viscosity of the obtained gel-like composition was measured using a DV-II viscometer (CPE-42 rotor) manufactured by Brookfield Co., Ltd. in an environment of 20 ° C. and a shear rate of 1.92 sec ^-1 (rotation speed 0.5 rpm). When the ink viscosity was measured under the conditions of 950 mPa · s, and when the ink viscosity was measured under the condition of a shear rate of 192 sec ^-1 (rotation speed 50 rpm), it was 113 mPa · s. The TI value at that time was 8.6.

<Examples 2 to 11>
A gel-like composition was obtained in the same manner as in Example 1 except that the gel-like composition was changed to the composition shown in Table 1.

（１）（メタ）アクリル酸－（メタ）アクリル酸メチル共重合体
（カルボン酸とメチルエステルのモル比１：２．１、
アクリル酸基とメタクリル酸基のモル比１：０．３６）
（２）（メタ）アクリル酸－（メタ）アクリル酸エチル共重合体
（カルボン酸とエチルエステルのモル比１：１、
アクリル酸基とメタクリル酸基のモル比１：０．８２）
（３）メチル変性量 ８／１００
（エチレンオキシドユニット１００に対しメチル変性８）
（４）フェニル変性量 1／１００ メチル変性量 １／１００
（エチレンオキシドユニット１００に対しフェニル変性１、メチル変性１）
（５）フェニル変性量 ２／１００
（エチレンオキシドユニット１００に対しフェニル変性２） <Comparative Examples 1 to 3>
A gel-like composition was obtained in the same manner as in Example 1 except that the gel-like composition was changed to the composition shown in Table 1.

(1) (Meta) acrylic acid- (meth) acrylic acid methyl copolymer (molar ratio of carboxylic acid to methyl ester 1: 2.1,
Mole ratio of acrylic acid group to methacrylic acid group 1: 0.36)
(2) (Meta) acrylic acid- (meth) ethyl acrylate copolymer (molar ratio of carboxylic acid to ethyl ester 1: 1),
Molar ratio of acrylic acid group to methacrylic acid group 1: 0.82)
(3) Methyl denaturation amount 8/100
(Methyl denaturation 8 for ethylene oxide unit 100)
(4) Phenyl denaturation amount 1/100 Methyl denaturation amount 1/100
(Phenyl denaturation 1 and methyl denaturation 1 for ethylene oxide unit 100)
(5) Phenyl denaturation amount 2/100
(Phenyl modification for ethylene oxide unit 100 2)

As shown in (Table 1), the gel-like compositions according to Examples 1 to 5, 9 and 10 use the same amount of copolymer as compared with Comparative Examples 1 and 2 in which no cross-linking agent is used. Despite the fact that it was present, a high viscosity was obtained when it was left to stand. In addition, the gel-like compositions according to Examples 6 to 8 and 11 had higher viscosities than Comparative Examples, even though the amount of the copolymer blended was smaller than that of Comparative Example 1. In particular, as can be seen from the results of Examples 6, 7 and 11, the viscosity gradients of the viscosity at the shear rate of 1.92 sec ^-1 and the viscosity at the shear rate of 192 sec ^-1 are different despite the small amount of the copolymer compounded. It was large and showed a higher TI value than the comparative example. Comparative Example 3 was an example using only the cross-linking agent, but it is clear that the thickening does not occur only with the cross-linking agent.
As described above, it has been clarified that the gel-like compositions of Examples 1 to 11 have high onset viscosity, high shear thinning, and exhibit good performance due to the effect of the combination of the copolymer and the cross-linking agent. ..

<Example 12>
An ink composition for writing tools was obtained by the following compounding composition and method.
(Water-based ink composition for writing tools 1)
Colored spherical resin particles (colorant) 10.0% by mass
Diethylene glycol (water-soluble organic solvent) 10.0% by mass
Triethanolamine (pH regulator) 3.0% by mass
Phosphoric acid ester (lauryl alcohol-based lubricant) 1.0% by mass
Benzotriazole (rust inhibitor) 0.5% by mass
1,2-Benz isothiazolin-3-one (preservative) 0.1% by mass
(Meta) Acrylic Acid-(Meta) Methyl Acrylic Acid Copolymer 0.45% by Mass
(Moral ratio of copolymer carboxylic acid to methyl ester 1: 2.1,
Mole ratio of acrylic acid group to methacrylic acid group 1: 0.36)
Polyoxyethylene tetraoleate (crosslinking agent) 1.8% by mass
Ion-exchanged water 73.16% by mass

A base ink was prepared by heating and stirring a colorant, water, a water-soluble organic solvent, a pH adjuster, a lubricant, a rust inhibitor, and a preservative with a disper. Then, while heating the base ink produced above, a shear thinning agent and a cross-linking agent are added, and the mixture is sufficiently mixed and stirred using a homogenizer stirrer until a uniform state is obtained. An ink composition was obtained. The ink viscosity of the obtained ink composition was obtained by using a DV-II viscometer (CPE-42 rotor) manufactured by Brookfield Co., Ltd. in an environment of 20 ° C. and a shear rate of 1.92 sec ^-1 (rotation speed 0.5 rpm). When the ink viscosity was measured under the condition of 1254 mPa · s, and when the ink viscosity was measured under the condition of a shear rate of 192 sec ^-1 (rotation speed 50 rpm), it was 106 mPa · s.

<Example 13>
An ink composition for a water-based ballpoint pen was obtained in the same manner as in Example 12 except that the ink composition was changed to the composition shown in Table 2.

<Comparative Examples 4 to 8>
An ink composition for a water-based ballpoint pen was obtained in the same manner as in Example 1 except that the ink composition was changed to the composition shown in Table 2.

（６）架橋型アクリル酸重合体（ハイビスワコー１０４ 和光純薬社製）
（７）架橋型アクリル酸－メタクリル酸アルキル共重合体
（Ｐｅｍｕｌｅｎ ＴＲ１ ルーブリゾール社製 アルキルの炭素数１０～３０）

(6) Cross-linked acrylic acid polymer (Hibiswaco 104 manufactured by Wako Pure Chemical Industries, Ltd.)
(7) Cross-linked acrylic acid-alkyl methacrylate copolymer (Pemmulen TR1 Lubrizol, alkyl having 10 to 30 carbon atoms)

Ink stability test: The ink compositions obtained in Examples 12 and 13 and Comparative Examples 4 to 8 were placed in a 50 ml screw tube, and the state was observed with a microscope at 50 ° C. for 2 months.
◯: No aggregation of colorants, etc. is observed, the initial state is maintained, and the ink stability is good.
Δ: Ink stability is slightly poor, such as slight aggregation of colorants and slight supernatant.
X: Aggregation of colorants and the like is observed, the initial state is not maintained, and the ink stability is poor.

A ballpoint pen tip (ball diameter: 0) in which the ink compositions obtained in Examples 12 and 13 and Comparative Examples 4, 7 and 8 are rotatably held at the tip of an ink containing cylinder with a ball diameter of 0.7 mm. Pilot Corporation It was mounted on a gel ink ballpoint pen (trade name: G-2) manufactured by Mf. Co., Ltd., and the following tests and evaluations were performed.

Writing property test 1: A gel ink ballpoint pen using the ink compositions obtained in Examples 12 and 13 and Comparative Examples 4, 7 and 8 was written on writing paper A at a writing angle of 65 degrees and a writing speed of 4 m / min. The bleeding state of the handwriting at that time was visually observed.
⊚: No bleeding is seen in the handwriting, and good handwriting is obtained.
◯: Slight bleeding is seen in the handwriting, but good handwriting is obtained.
Δ: There is bleeding in the handwriting, but the handwriting has no problem in practical use.
×: The handwriting is severely blurred, and the handwriting is practically problematic.

Writing property test 2: A gel ink ballpoint pen using the ink compositions obtained in Examples 12 and 13 and Comparative Examples 4, 7 and 8 was written on writing paper A at a writing angle of 65 degrees and a writing speed of 4 m / min. The state of line cracking of the handwriting at that time was visually observed.
◯: No line cracks were observed in the handwriting, and a uniform and good handwriting was obtained.
Δ: Line cracks are seen in the handwriting, but the handwriting that has no problem in practical use is obtained.
×: The line cracking of the handwriting is severe, and the handwriting is practically problematic.

As shown in (Table 2), the ink compositions according to Examples 12 and 13 were excellent in both ink stability and writability. On the other hand, in the ballpoint pens using the ink compositions of Comparative Examples 4, 7 and 8, bleeding and line cracking were observed when writing, and it was clarified that the performance was inferior.
As described above, it has been clarified that the ink compositions of Examples 12 and 13 and the water-based ballpoint pen using the same show good performance by using a specific copolymer and a cross-linking agent.

The gel-like composition of the present invention includes various ink compositions such as writing instrument ink compositions, cleaning agents, sanitary products, toiletry products, personal care products, healthcare products, cosmetics, medical products, pharmaceuticals, agricultural products, electrodes, batteries, etc. Can be used for. Further, when the ink composition is used, it can be used as a writing tool such as a cap type, a knock type ballpoint pen, and various markers.

Claims (6)

water and,
A copolymer obtained by copolymerizing a monomer represented by the following general formula (1) and a monomer represented by the following general formula (2), and
With a cross- linking agent
A gel-like composition comprising
A gel-like composition in which the ratio of the acrylic acid group to the methacrylic acid group of the copolymer is 1: 0.1 to 1: 2 in terms of molar ratio .

(R ₁ in the formula is a hydrogen or methyl group)

(In the formula, R ₂ is a hydrogen or methyl group, and R ₃ is an alkyl group having a linear or side chain having 1 to 5 carbon atoms). The gel-like composition according to claim 1, wherein the ratio of the carboxylic acid to the carboxylic acid ester of the copolymer is 1: 0.05 to 1:10 in terms of molar ratio. The gel-like composition according to claim 1 or 2 , wherein the cross-linking agent is a compound capable of exhibiting an intermolecular cohesive force due to the copolymer and van der Waals. Claims 1 to 3 wherein the cross-linking agent is selected from the group consisting of alkyl-modified glucose, polyoxyethylene sorbitan fatty acid ester, polyoxyethylene fatty acid ester, alkyl-modified polyethylene oxide, phenyl-modified polyethylene oxide, and phenylalkyl-modified polyethylene oxide. The gel-like composition according to any one of the above. A water-based ink composition for writing tools comprising the gel-like composition according to any one of claims 1 to 4 and a colorant. A writing tool comprising the water-based ink composition for writing tools according to claim 5 .