JP2023028097A - Ink composition for aqueous pens - Google Patents

Abstract

To provide an ink composition for aqueous pens that is free from the aggregation of pigment, does not cause a lowered drying rate, has improved ink viscosity, and contains a small amount of pigment added.SOLUTION: An ink composition for aqueous pens contains a water-soluble organic solvent with a boiling point of lower than 200°C, a water-soluble organic solvent with a boiling point of 200°C or higher, pigment and water. When the total amount of the ink composition for aqueous pens is 100 mass%, the water-soluble organic solvent with a boiling point of lower than 200°C is 10.0 mass% or more and 25.0 mass% or less, the water-soluble organic solvent with a boiling point of 200°C or higher is 5.0 mass% or more and 15.0 mass% or less, and the pigment is 0.05 mass% or more and 3.0 mass% or less.SELECTED DRAWING: None

Description

The present invention relates to an ink composition for water-based pens. In particular, the present invention relates to a water-based pen ink composition having a low pigment content and useful for felt-tip pens and marking pens.

Various color tones are known as ink compositions for water-based pens. Of these, the content of the pigment dispersion should be reduced when preparing a water-based pen ink composition with a gray tone. On the other hand, when the content of the pigment dispersion is small, the viscosity of the water-based pen ink composition may not be appropriate.
For this reason, adding a thickening agent has been performed as one of the general methods for increasing the viscosity of the ink composition for water-based pens. However, in the case of a low-viscosity water-based pen ink composition having a viscosity of less than 100 mPa·s, for example, the thickener may act as a pigment flocculant, causing aggregation of the pigment.
Further, by adding a water-soluble organic solvent having a high boiling point and a high viscosity, it is possible to increase the viscosity of the water-based pen ink composition. However, there is a problem that the drying speed becomes slow.

Patent Document 1 describes an aqueous ink composition for writing instruments containing a colorant, water and a nonionic surfactant. Specifically, pigment inks for water-based ballpoint pens containing carbon black, nonionic surfactants, glycerin, propylene glycol, water and the like are described. This pigment ink for water-based ball-point pens has a high pigment content and is not a grayish tone ink.

Patent Document 2 describes an aqueous ink composition for writing instruments containing water, a coloring agent, and glyceryl glucoside. Specifically, pigment inks for water-based marking pens containing blue pigments, water-soluble organic solvents (glycerin and ethylene glycol), water and the like are described. This pigment ink for water-based ball-point pens has a high pigment content and is not a light-colored ink.

JP-A-2004-256758 JP 2018-178113 A

The problem to be solved by the present invention is to provide a water-based pen ink composition that does not cause aggregation of pigments, does not slow down the drying rate, has an increased ink viscosity, and contains a small amount of pigments.

Means for Solving the Problems As a result of intensive studies in order to solve the above problems, the present inventors have found that the above problems can be solved by the following ink composition for water-based pens, and have completed the present invention. Specifically, it is as follows.
[1] A water-soluble organic solvent having a boiling point of less than 200°C, a water-soluble organic solvent having a boiling point of 200°C or more, a pigment and water, and the total amount of the water-based pen ink composition being 100% by mass,
10.0% by mass or more and 25.0% by mass or less of a water-soluble organic solvent having a boiling point of less than 200°C;
5.0% by mass or more and 15.0% by mass or less of a water-soluble organic solvent having a boiling point of 200°C or higher;
0.05% by mass or more and 3.0% by mass or less of pigment,
Included are ink compositions for water-based pens.
[2] The ink composition for water-based pens according to [1], wherein the coating film of the ink composition for water-based pens has a lightness L ^* value of 30 or more and 80 or less in the L ^* a ^* b ^* color system.
[3] A water-based pen comprising a core containing the ink composition for a water-based pen according to [1] or [2].

ADVANTAGE OF THE INVENTION According to this invention, the ink composition for water-based pens which does not coagulate a pigment, does not slow down a drying speed, has an increased ink viscosity, and has a small amount of pigment added is provided. This ink composition for water-based pens can be suitably used as an ink composition for marking pens and felt-tip pens, particularly core-type water-based pens.

[Ink composition for water-based pen]
The ink composition for water-based pens of the present invention contains at least a water-soluble organic solvent having a boiling point of less than 200°C, a water-soluble organic solvent having a boiling point of 200°C or more, a pigment and water, and further comprises a resin emulsion, a surfactant and a dispersant. , preservatives, antifungal agents. Each component will be described in detail below.

<Water-soluble organic solvent having a boiling point of less than 200°C>
The water-soluble organic solvent having a boiling point of less than 200°C has a solubility in water at 20°C of 1 g/L or more, preferably 10 g/L or more, more preferably 100 g/L or more, and most preferably mixed uniformly at any ratio. is an organic solvent having a boiling point of less than 200°C. Examples include monoalcohols, polyhydric alcohols, lower alkyl ethers of polyhydric alcohols having 1 to 6 carbon atoms, ketones, ethers, esters, and nitrogen-containing compounds. These are used individually by 1 type or in mixture of 2 or more types.

Examples of monoalcohols are selected from the group consisting of methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-heptanol, n-octanol, cyclopentanol, cyclohexanol, and the like. One or more types are mentioned.
Examples of polyhydric alcohols include one or more selected from the group consisting of ethylene glycol, propylene glycol, and the like.

Examples of lower alkyl ethers of polyhydric alcohols having 1 to 6 carbon atoms include ethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, One or more selected from the group consisting of propylene glycol monopropyl ether, dipropylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether and the like.

Among these, ethylene glycol and/or propylene glycol are preferred.
The content of the water-soluble organic solvent having a boiling point of less than 200°C is 10.0% by mass or more, preferably 15.0% by mass or more, and 25.0% by mass, based on the total amount of the water-based pen ink composition as 100% by mass. Below, preferably 20.0% by mass or less. If the content of the water-soluble organic solvent having a boiling point of less than 200° C. is less than 10.0% by mass, the storage stability of the aqueous pen ink composition may deteriorate. If the content of the water-soluble organic solvent having a boiling point of less than 200°C exceeds 25.0% by mass, the ink drying speed and storage stability of the water-based pen ink composition may deteriorate.

<Water-soluble organic solvent having a boiling point of 200°C or higher>
The water-soluble organic solvent having a boiling point of 200°C or higher has a solubility in water at 20°C of 1 g/L or higher, preferably 5 g/L or higher, more preferably 100 g/L or higher, and most preferably mixed uniformly at any ratio. is an organic solvent having a boiling point of 200° C. or higher. Examples include polyhydric alcohols, alkyl ethers of polyhydric alcohols, ketones, ethers, esters, and nitrogen-containing solvents. These are used individually by 1 type or in mixture of 2 or more types.

Examples of polyhydric alcohols include 1,3-propanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol and 1,6-hexanediol. , 1,2-heptanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-1,3-propanediol, 2-ethyl-2-methyl-1,3-propanediol, 3-methyl -1,3-butanediol, 3-methyl-1,5-pentanediol, 2-methyl-2-propyl-1,3-propanediol, 2-ethyl-1,3-hexanediol, 1,2-octane One or more selected from the group consisting of diols, diethylene glycol, triethylene glycol, dipropylene glycol, butylene glycol, dibutylene glycol, glycerin and the like.

Examples of alkyl ethers of polyhydric alcohols include diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, diethylene glycol monohexyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, and triethylene glycol monopropyl ether. , triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monobutyl ether, dipropylene glycol monopropyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, diethylene glycol butyl methyl ether , triethylene glycol dimethyl ether, triethylene glycol methyl ethyl ether, triethylene glycol butyl methyl ether, triethylene glycol diethyl ether, tetraethylene glycol dimethyl ether, tetraethylene glycol methyl ethyl ether, tetraethylene glycol butyl methyl ether, tetraethylene glycol diethyl ether One or more selected from the group consisting of glycol dialkyl ethers such as

Examples of esters include one or more selected from the group consisting of γ-butyrolactone, γ-valerolactone, δ-valerolactone, ε-caprolactone and the like.

Nitrogen-containing solvents include, for example, 2-pyrrolidone, N-methylpyrrolidone, N-ethylpyrrolidone, ε-caprolactam, 3-methyl-2-oxazolidinone, 3-ethyl-2-oxazolidinone, N,N-dimethyl-β -methoxypropionamide, N,N-dimethyl-β-ethoxypropionamide, N,N-dimethyl-β-butoxypropionamide, N,N-dimethyl-β-pentoxypropionamide, N,N-dimethyl-β- hexoxypropionamide, N,N-dimethyl-β-heptoxypropionamide, N,N-dimethyl-β-2-ethylhexoxypropionamide, N,N-dimethyl-β-octoxypropionamide, N,N -diethyl-β-butoxypropionamide, N,N-diethyl-β-pentoxypropionamide, N,N-diethyl-β-hexoxypropionamide, N,N-diethyl-β-heptoxypropionamide, N, One or more selected from the group consisting of N-diethyl-β-octoxypropionamide and the like.

Among these, glycerin and/or 1,6-hexanediol are preferred.
The content of the water-soluble organic solvent having a boiling point of 200° C. or higher is 5.0% by mass or more and 15.0% by mass or less, preferably 10.0% by mass, based on the total amount of the water-based pen ink composition as 100% by mass. It is below. If the content of the water-soluble organic solvent having a boiling point of 200° C. or higher is less than 5.0% by mass, the storage stability of the water-based pen ink composition may deteriorate. If the content of the water-soluble organic solvent having a boiling point of 200° C. or higher exceeds 15.0% by mass, the ink drying speed of the water-based pen ink composition may decrease.

<Pigment>
As the pigment, one or more of various pigments conventionally used in ink compositions for water-based pens, such as inorganic pigments, extender pigments, organic pigments and colored resin spheres, can be used so as to obtain a desired color tone.

Examples of inorganic pigments include carbon black, graphite, titanium oxide, zinc oxide, red iron oxide, yellow iron oxide, ultramarine blue, Prussian blue, metal powders such as aluminum powder and bronze powder, talc, silica, alumina, mica, and alumina silicate. One or more selected from the group consisting of extender pigments, fluorescent pigments, glass flakes, luster pigments, and the like.
Examples of organic pigments include phthalocyanine, azo, quinacdrine, anthraquinone, isoindolinone, diketopyrrolopyrrole, dioxane, indigo, thioindigo, perinone, perylene, indolenone, One or more selected from the group consisting of azomethine-based coloring pigments, fluorescent pigments, and the like can be used.

The colored resin spheres are spherical, amorphous, hollow, or flat resin spheres colored with one or more inorganic pigments, organic pigments, or dyes exhibiting arbitrary color tones. Examples of the resin material forming the colored resin spheres include polyethylene, polypropylene, vinyl chloride, polymethacrylate, benzoguanamine, melamine resin, and nylon.
As the inorganic pigment and the organic pigment for imparting a color tone to the colored resin spheres, one or more kinds selected from the group consisting of the inorganic pigments and the organic pigments can be used. As the dye for imparting a color tone to the colored resin spheres, water-soluble dyes are preferable, and direct dyes, acid dyes, food dyes, basic dyes, for example, anthraquinone-based, methine-based, carbonium-based, and metal complex-based colorings. One or more selected from the group consisting of dyes, fluorescent dyes, and the like can be mentioned.

The color tone of the coating film of the aqueous pen ink composition of the present invention is preferably a light color tone. For this reason, it is preferable that the coating film of the water-based pen ink composition has a lightness L ^* value of 30 or more and 80 or less in the L ^* a ^* b ^* color system.
In particular, it is preferable that only a black pigment such as carbon black is contained as the pigment so that the coating film of the water-based pen ink composition has a grayish color tone. In addition, in addition to black pigments such as carbon black, as pigments, in addition to black pigments such as blue, red, green, purple, yellow, etc., preferably contains a pigment with a color tone of

The content of the pigment is 0.05% by mass or more, preferably 0.15% by mass or more, and preferably 3.0% by mass or less, preferably 1.0% by mass, based on the total amount of the water-based pen ink composition as 100% by mass. It is 5% by mass or less. If the content of the pigment is less than 0.05% by mass, the color tone of the water-based pen ink composition may become too light, and the desired color tone may not be achieved, resulting in poor color development. If the content of the pigment exceeds 3.0% by mass, the color tone of the ink composition may become too dark and the intended color tone may not be obtained.

<Water>
Water-based pen ink compositions contain water that functions as a solvent to dissolve the constituents. As water, for example, tap water, purified water, distilled water, ion-exchanged water, or pure water is used. Pure water, ion-exchanged water, distilled water, or the like is preferably used.

The water content can be appropriately adjusted according to the content, viscosity, etc. of each component in the water-based pen ink composition. It is, for example, 25.0% by mass or more, preferably 30.0% by mass or more, and 45.0% by mass or less, preferably 40.0% by mass or less, based on the total amount of the water-based pen ink composition being 100% by mass. If the water content is less than 25.0% by mass, the viscosity of the ink composition for water-based pens becomes high, and the amount of ink flowing out during writing may become inappropriate, resulting in blurring and the like. may decrease. If the water content exceeds 45.0% by mass, the viscosity of the ink composition for water-based pens becomes low, and the amount of ink flowing out during writing may become inappropriate, resulting in bleeding and ink leakage. There is a risk of

<Resin emulsion>
The ink composition for water-based pens of the present invention contains a resin emulsion having a film-forming property at room temperature in order to increase the viscosity and fix the handwriting on the appropriate writing surface when the solvent evaporates after writing. It is preferable to contain.
Examples of resin emulsions include emulsions of one or more resins selected from the group consisting of acrylic resins, styrene-(meth)acrylic resins, styrene-maleic acid resins, vinyl acetate resins, urethane resins, and the like. mentioned.

Examples of the acrylic resin emulsion include one or more selected from the group consisting of the PRIMAL series manufactured by Dow Chemical Japan, the Rheovis series manufactured by BASF, and the like.
Examples of the styrene-(meth)acrylic resin emulsion include one or more selected from the group consisting of Joncryl series manufactured by Johnson Polymer Co., Ltd., Movinyl series manufactured by Japan Coating Resin Co., Ltd., and the like.
Examples of the styrene-maleic acid resin emulsion include one or more selected from the group consisting of the X series manufactured by Seiko PMC.
Examples of the vinyl acetate resin emulsion include one or more selected from the group consisting of the Nikasol series and the like.

When the water-based pen ink composition contains a resin emulsion, the content is not particularly limited. The resin emulsion solid content is, for example, 5.0% by mass or more, preferably 7.0% by mass or more, and, for example, 15.0% by mass or less, preferably 10.0% by mass, based on the total amount of the water-based pen ink composition being 100% by mass. % by mass or less. If the content of the resin emulsion solids is less than 5.0% by mass, the viscosity of the water-based pen ink composition becomes low, and the amount of ink flowing out during writing may become inappropriate, resulting in bleeding. Leakage may occur. If the content of the resin emulsion solid content exceeds 15.0% by mass, the viscosity of the water-based pen ink composition increases, and the amount of ink flowing out during writing may become inappropriate, causing blurring and the like. There is a possibility that the cap-off property may deteriorate.

<Dispersant>
The ink composition for water-based pens of the present invention may contain a dispersant in order to improve the storage stability of the ink, increase the viscosity of the ink, and improve the dispersibility of the pigment. The dispersant may function as a vehicle/fixer for forming a coating film of the water-based pen ink composition.
The dispersant is not particularly limited, and commercially available ones can be used. For example, water-soluble and/or water-dispersible resins and surfactants can be used.

Examples of water-soluble and/or water-dispersible resins include (meth)acrylic resins, maleic acid-based resins, styrene-(meth)acrylic-based resins, styrene-maleic acid-based resins, polyvinylpyrrolidone-based resins, polyvinylalco- One or more resins selected from the group consisting of cellulose-based resins, water-soluble urethane-based resins, cellulose-based resins such as sodium carboxymethylcellulose, and the like.

Surfactants are selected from anionic, cationic, nonionic and amphoteric surfactants. For example, anionic surfactants such as alkylbenzenesulfonic acid (salt), alkylsulfosuccinic acid, alkylphenyl phosphate; polyoxyalkylene alkyl ether, polyoxyalkylene fatty acid ester, polyoxyalkylene alkylaryl ether, sorbitan esters, alkyl One or more selected from the group consisting of nonionic surfactants such as phosphate esters; fluorine-based surfactants, and the like.
In the present invention, among these dispersants, nonionic surfactants having wetting/penetrating functions, emulsifying functions and dispersing functions, particularly surfactants containing phosphorus atoms (e.g., phosphanol (Toho Chemical Industry Co., Ltd.) Product name) is preferably used.

When the water-based pen ink composition contains a dispersant, the content is not particularly limited. The solid content of the dispersant is, for example, 10.0% by mass or more, and is, for example, 20.0% by mass or less, preferably 15.0% by mass or less, based on the total amount of the water-based pen ink composition being 100% by mass. If the solid content of the dispersant is less than 10.0% by mass, the storage stability of the ink composition for water-based pens may deteriorate, and the amount of ink flowing out during writing may become inappropriate, resulting in ink leakage. It may occur. When the solid content of the dispersant exceeds 15.0% by mass, the viscosity of the water-based pen ink composition increases, and the amount of ink flowing out during writing may become inappropriate, causing blurring and the like. .

<Other additives>
The water-based pen ink composition of the present invention may contain other additives, if necessary. Other additives are not particularly limited as long as they are used in water-based pen ink compositions. For example, surfactants, preservatives, antifungal agents, wetting agents, dyes, lubricants, antifoaming agents, leveling agents, ultraviolet absorbers, infrared absorbers, antioxidants, dyes, fluorescent brighteners, viscosity modifiers ( One or more selected from the group consisting of thickeners), pH adjusters and the like can be used in an appropriate amount as necessary.

Examples of the surfactant include one or more selected from the group consisting of the same surfactants as described in <Dispersant>.
Examples of antiseptic agents and antiseptic agents include benzoisothiazoline antiseptic antiseptic agent, pentachlorophenol antiseptic antiseptic agent, cresol antiseptic antiseptic agent, propylene glycol antiseptic antiseptic agent, and iodine. One or more selected from the group consisting of antiseptic antifungal agents and the like.

Dyes include direct dyes, acid dyes, basic dyes, mordant/acid mordant dyes, alcohol-soluble dyes, azoic dyes, sulfur/sulfide vat dyes, vat dyes, disperse dyes, and One or more selected from the group consisting of arbitrary dyes such as oil-soluble dyes, food dyes, metal complex dyes, salt-forming dyes, and dyes obtained by dyeing resins, and aqueous solutions thereof.

Other additives include inorganic salts such as sodium carbonate, sodium phosphate, and sodium acetate; pH adjusters such as organic basic compounds such as water-soluble amine compounds; Rust agents; wetting agents such as urea, sorbitol, mannitol, sucrose, glucose, reduced starch hydrolysates and sodium pyrophosphate; antifoaming agents; one or more selected from the group consisting of antioxidants and the like.
Additionally, a lubricant may be added. Lubricants include metal soaps, polyalkylene glycol fatty acid esters, ethylene oxide addition type cationic surfactants, phosphoric acid ester surfactants, N-acyl amino acid surfactants, dicarboxylic acid surfactants, β-alanine surfactants. active agents, 2,5-dimercapto-1,3,4-thiadiazole and its salts and oligomers, 3-amino-5-mercapto-1,2,4-triazole, thiocarbamate, dimethyldithiocarbamate, α- One or more selected from the group consisting of lipoic acid, condensates of N-acyl-L-glutamic acid and L-lysine, salts thereof, and the like.
In addition, N-vinyl-2-pyrrolidone oligomer, N-vinyl-2-piperidone oligomer, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, ε-caprolactam, N-vinyl-ε-caprolactam Addition of thickening inhibitors such as oligomers can also enhance functionality in the hive-and-recess form.

<L ^* a ^* b ^* chromaticity a ^* value, chromaticity b ^* value, and lightness L ^* value in the color system>
The L ^* a ^* b ^* color system is a chromaticity a ^* value, a chromaticity b ^* value, and lightness L ^* Composed of values.
The lightness L ^* value indicates that the closer to 0, the stronger the blackness, and the closer to 100, the stronger the whiteness. If the lightness L ^* value is 30 or more and 80 or less, it is a gray tone area.
The chromaticity a ^* value indicates that the larger the value on the positive side, the stronger the reddishness, and the larger the value on the negative side, the stronger the greenishness.
The chromaticity b ^* value indicates that the larger the value on the plus side, the stronger the yellowness, and the larger the value on the minus side, the stronger the bluishness.

The ranges of the chromaticity a* value, the chromaticity b ^* value, and the lightness ^{L* value} , which indicate the hue and saturation in the L ^* a ^* b ^* color system, of the coating film of the water-based pen ink composition of the present invention are: It is not particularly limited.
For gray tone regions, the range of lightness L ^* values is, for example, 30 or more, preferably 35 or more, more preferably 40 or more, for example 80 or less, preferably 70 or less, more preferably 65 or less.
For the gray tone region, the range of chromaticity a ^* values is, for example, −20.0 or more, preferably −15.0 or more, more preferably −6.0 or more, for example +20.0 or less, preferably +15. 0.0 or less, more preferably −0.5 or less. For example, when the chromaticity a ^* value is in the range of −6.0 or more and −0.5 or less, it becomes an achromatic gray tone range, and for example, the closer to −20.0, the more greenish gray tone range. The closer the value is to +20.0, the more reddish the clay tone range becomes.
In the gray tone region, the range of chromaticity b ^* values is, for example, −20.0 or more, preferably −15.0 or more, more preferably +3.0 or more, for example +20.0 or less, preferably +15.0. It is 0 or less, more preferably +10.0 or less. For example, when the chromaticity b ^* value is in the range of +3.0 or more and +10.0 or less, it becomes an achromatic gray tone range. The closer to , the more yellowish the clay tone range becomes.
Examples of the method for measuring the lightness L ^* value in the L ^* a ^* b ^* color system include the method described in Examples below.

<Viscosity>
The viscosity of the water-based pen ink composition of the present invention is not particularly limited and can be set as appropriate. In particular, it is preferable that the viscosity of the aqueous pen ink composition is 100 mPa·s or less. For example, 1.0 mPa s or more, preferably 2.0 mPa s or more, more preferably 3.0 mPa s or more, for example 35.0 mPa s or less, preferably 15.0 mPa s or less, more preferably 6 0 mPa·s or less (E type rotational viscometer (for example, Toki Sangyo Co., Ltd., TVE type viscometer, 1°34′ cone, 50 rpm)). If the viscosity of the ink composition for a water-based pen is less than 1.0 mPa·s, the ink may flow excessively from the tip of the writing instrument, making it impossible to accurately form a handwriting. If the viscosity exceeds 35.0 mPa·s, the viscosity becomes too high, and the ink may not flow out from the tip of the writing instrument. It could be a problem.

<Method for producing ink composition for water-based pen>
The method for producing the water-based pen ink composition of the present invention is not particularly limited. Any known method for producing an aqueous ink composition can be used.
For example, all components constituting the ink composition for water-based pens are put into a container, and a mixing/stirring device such as a ball mill, bead mill, roll mill, Henschel mixer, homomixer, propeller stirrer, homogenizer, high-pressure homogenizer, kneader, dissolver, etc. can be used to mix and stir to disperse, to prepare a water-based pen ink composition.

For example, some components of the ink composition for water-based pens, such as pigments, water-soluble organic solvents, water, dispersants, etc., are put into a container, and mixed and stirred by the above-described mixing and stirring device to disperse. After producing a pigment dispersion, the rest of the components are added and mixed and stirred to produce an ink composition for water-based pens.
When preparing the ink composition for water-based pens, coarse particles, gases, and air bubbles may be removed by performing operations such as filtration, centrifugation, defoaming, and the like. Means such as heating, cooling, pressurization, depressurization, inert gas replacement, etc. can also be employed when preparing the ink composition for water-based pens. Furthermore, you may perform an aging process after the ink composition for water-based pens is produced.

[Water-based pen]
A water-based pen comprising the ink composition for a water-based pen of the present invention comprises a pen tip made of a fiber core or a plastic core, and an ink container, and the ink composition for a water-based pen is contained in the ink container. It is a water-based pen.
The ink composition for water-based pens of the present invention can be suitably used as an ink composition for water-based marking pens and water-based felt-tip pens, particularly core-type water-based pens.
As a water-based marking pen, for example, it is a writing instrument called a felt pen, which has a pen tip made of a fiber bundle, a sintered body or plastic, and a so-called core made of felt or a fiber bundle in the main body is impregnated with ink. A so-called center core type marking pen is a writing utensil that is provided with an ink storage means and supplies ink from such an ink storage means to the pen tip by utilizing capillary action to enable writing. There is also a non-core type or so-called free ink type marking pen in which ink is stored as it is in a cylindrical main body and the ink is supplied to the pen tip.
The water-based pen ink composition according to the present invention is suitable for use in any of these marking pens.

EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass".

The following components were used as components constituting the water-based pen ink compositions described in the Examples.
・ Carbon black: MONARCH 800 manufactured by Cabot
・Blue pigment: FASTOGEN BLUE FDB71 manufactured by DIC
・ Styrene - (meth) acrylic resin A: BASF Japan Co., Ltd., Joncryl 683
・Styrene-(meth)acrylic resin B: Hylos X-1 manufactured by Seiko PMC Co., Ltd.
・Acrylic emulsion: Movinyl 790 manufactured by Japan Coating Resin Co., Ltd.
・Preservative: Proxel XL-2 manufactured by Lonza Japan
・Antifungal agent: Courtside PH2 manufactured by Osaka Gas Chemicals Co., Ltd.
・Surfactant: Polyoxyethylene nonylphenyl phosphate (Toho Chemical Industry Co., Ltd., Phosphanol)

[Examples 1 to 4, Comparative Examples 1 to 4]
<Preparation of Pigment Dispersion A>
Carbon black 25.0 parts, ethylene glycol 20.0 parts, styrene - (meth) acrylic resin A 25.0 parts, antiseptic agent 0.1 part, antifungal agent 0.1 part, and deionized water 29.8 The parts were mixed in a bead mill to prepare Pigment Dispersion A.

<Preparation of Pigment Dispersion B>
25.0 parts of blue pigment, 5.0 parts of butyl cellosolve, 20.0 parts of ethylene glycol, 25.0 parts of styrene-(meth)acrylic resin B, and 25.0 parts of ion-exchanged water are mixed in a bead mill and mill base. B was prepared.
To 68.0 parts of the obtained millbase B, 0.1 part of a preservative, 0.1 part of an antifungal agent, and 31.8 parts of ion-exchanged water were added and mixed with a stirrer to prepare a pigment dispersion B. .

<Preparation of ink composition for water-based pen>
(Example 1)
Pigment dispersion A 3.3 parts, pigment dispersion B 1.2 parts, glycerin 5.0 parts, ethylene glycol 20.0 parts, styrene-(meth)acrylic resin B 15.0 parts, acrylic emulsion A7. 0 parts of a surfactant, 0.1 parts of a preservative, 0.1 parts of an antifungal agent, 15.0 parts of urea, and 33.2 parts of ion-exchanged water are mixed with a stirrer and centrifuged. to remove coarse particles in the ink to prepare an ink composition for a water-based pen according to Example 1.

(Examples 2-4, Comparative Examples 1-3)
Water-based pen ink compositions according to Examples 2 to 4 and Comparative Examples 1 to 3 were prepared in the same manner as in Example 1, except that the components of the water-based pen ink composition were as shown in Table 1. bottom.

<Production of water-based pen>
Attach the tip to the pen body (core felt pen made by Sakura Crepas) and attach the cap. Each of the ink compositions for water-based pens of Examples 1 to 4 and Comparative Examples 1 to 3 was filled into a core, put into a pen body, and attached with a tail plug to prepare a water-based pen.

<Evaluation>
The aqueous pen ink compositions of Examples 1 to 4 and Comparative Examples 1 to 3 were evaluated as follows. The results are also shown in Table 1 or Table 2.

<Viscosity>
Using an E-type rotational viscometer (TVE viscometer manufactured by Toki Sangyo Co., Ltd.), the viscosity was measured under the measurement conditions of 1°34′ cone, 50 rpm, and 20°C. Table 1 shows the results.
In the present invention, a sample with a viscosity of 4.5 mPa·s±1.5 mPa·s was considered acceptable.

<Drying speed>
In a room with a temperature of 20° C. and a humidity of 65%, 100 V-shapes were written on high-quality paper using the water-based felt-tip pens produced, one for each second.
After writing, the glossy surface of the piece of art paper was placed on the paper on which the writing had been written, and a writing line was traced five times on the piece of art paper with a weight of 500 g.
The piece of art paper was removed, and the number of seconds from the last written V to the V that had been transferred to the piece of art paper was counted, and the number of seconds was defined as the drying speed (seconds). Table 1 shows the results.
In the present invention, the case where the drying speed was within 60 seconds was regarded as acceptable.

<L ^* value>
Cores were taken out from felt-tip pens produced using the ink compositions for water-based pens of Examples 1 and 3 and Comparative Example 1, and the cores and the ink compositions for water-based pens were separated. In this embodiment, the separation was performed using a centrifuge.
A water-based pen ink composition was applied onto fine paper using a bar coater. The bar coater used had a rod number of 9 and an operating speed of 3 cm/s.
After drying the coating film for one day or longer, the L ^* value, a ^* value and b ^* value of the coating film were measured using a spectrophotometer (SE-2000, manufactured by Nippon Denshoku Co., Ltd.). The results are shown in Table 2

From Tables 1 and 2, the water-based pen ink compositions of the present invention according to Examples 1 to 4 have a water-soluble organic solvent with a boiling point of less than 200°C, a water-soluble organic solvent with a boiling point of 200°C or more, and a pigment. It can be seen that by making each specific range, excellent properties are obtained in all respects of color tone, viscosity and drying speed. On the other hand, when the content of the water-soluble organic solvent having a boiling point of less than 200°C and the water-soluble organic solvent having a boiling point of 200°C or higher is outside the specific range, any one or more of color tone, viscosity and drying rate are satisfactory. I know it's not a lot. Also, it can be seen that when the amount of pigment is large as in Comparative Example 3, the lightness L ^* value is low.

Claims (3)

A water-soluble organic solvent with a boiling point of less than 200 ° C., a water-soluble organic solvent with a boiling point of 200 ° C. or higher, a pigment and water,
Assuming that the total amount of the water-based pen ink composition is 100% by mass,
10.0% by mass or more and 25.0% by mass or less of a water-soluble organic solvent having a boiling point of less than 200°C;
5.0% by mass or more and 15.0% by mass or less of a water-soluble organic solvent having a boiling point of 200°C or higher;
0.05% by mass or more and 3.0% by mass or less of pigment,
Included are ink compositions for water-based pens. 2. The water-based pen ink composition according to claim 1, wherein the coating film of the water-based pen ink composition has a lightness L ^* value of 30 or more and 80 or less in the L ^* a ^* b ^* color system. An aqueous pen comprising a core containing the ink composition for an aqueous pen according to claim 1 or 2.