Water-based ink composition for felt-tip pens

Abstract

To provide a water-based ink composition for a felt-tip pen having improved "handwriting drying property" of rapidly drying handwriting, and to provide a water-based ink composition for a felt-tip pen having improved "handwriting drying property" of rapidly drying handwriting and improved "cap-off property".SOLUTION: The water-based ink composition for felt-tip pens comprises (A) water, (B) a colorant, (C) a styrene - (meth) acrylic acid-based resin, and (D) a polyoxyethylene alkyl ether-type surfactant and / or a polyoxyethylene alkyl phenyl ether-type surfactant, and may further comprise (E) a wetting agent.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a water-based ink composition for a felt-tip pen, and more particularly to a water-based ink composition for a felt-tip pen that has excellent writing drying properties. [Background technology]

[0002] Various types of water-based ink compositions for felt-tip pens are known. Water-based felt-tip pens using these water-based ink compositions for felt-tip pens are required to dry handwriting quickly after writing.

[0003] Patent Document 1 discloses a water-based ink composition for a felt-tip pen, which contains a color base containing a colorant, a styrene-(meth)-acrylic resin, and a surfactant (phosphanol: a phosphorus-based surfactant), as well as ethylene glycol, glycerin, urea, and water. This water-based ink composition for a felt-tip pen is said to be able to prevent smearing when writing with the water-based pen after long-term storage.

[0004] Patent Document 2 discloses an aqueous ink composition for a felt-tip pen, which contains water, solid silicone particles, and a colorant. This aqueous ink composition for a felt-tip pen is said to have a good writing feel.

[0005] Patent Document 3 discloses an aqueous ink composition for ballpoint pens and felt-tip pens, which contains a colorant, water, and reduced dextrin or reduced maltodextrin. This aqueous ink composition for ballpoint pens and felt-tip pens is said to have excellent resistance to drying, to be safe, and to be free from fluctuations in viscosity and pH. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 2023-167967 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-125097 [Patent Document 3] Patent No. 3534118 Summary of the Invention [Problem to be solved by the invention]

[0007] Conventional water-based ink compositions for felt-tip pens have been required to have improved penetration into paper and drying properties when writing on paper. The aqueous ink composition for a felt-tip pen disclosed in Patent Document 1 contains a phosphate ester surfactant as a surfactant. Phosphate ester surfactants contain a phosphate ester group as a functional group and an anionic moiety derived from the phosphate ester group, which makes them highly polar, and further improvements in penetration into paper and drying of handwriting after writing have been desired. The aqueous ink composition for a felt-tip pen disclosed in Patent Document 2 and the aqueous ink composition for a ballpoint pen and a felt-tip pen disclosed in Patent Document 3 do not take into consideration penetration into paper and drying of handwriting after writing.

[0008] In order to speed up the drying of handwriting after writing in an aqueous ink composition for a felt-tip pen, it is conceivable to increase the evaporation rate of the solvent in the aqueous ink composition for a felt-tip pen. However, when the evaporation rate of the solvent in the aqueous ink composition for a felt-tip pen is increased, evaporation of the solvent in the aqueous ink composition for a felt-tip pen proceeds when the pen is not capped, which may cause problems such as smearing of handwriting during writing and solidification of the ink in the felt-tip pen.

[0009] One of the problems to be solved by the present invention is to provide a water-based ink composition for a felt-tip pen that has improved "handwriting drying properties" so that handwriting dries quickly. One of the problems that the present invention aims to solve is to provide an aqueous ink composition for a felt-tip pen that has improved "handwriting drying properties" so that handwriting dries quickly and has improved "cap-off properties." [Means for solving the problem]

[0010] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that the above-mentioned problems can be solved by the following aqueous ink composition for felt-tip pens, and have thus completed the present invention. [Section 1] (A) Water, (B) a colorant; (C) a styrene-(meth)acrylic acid-based resin, and (D) polyoxyethylene alkyl ether surfactant and / or polyoxyethylene alkyl phenyl ether surfactant, A water-based ink composition for a felt-tip pen, comprising: [Section 2] Item 1. The aqueous ink composition for a felt-tip pen according to Item 1, further comprising (E) a wetting agent, the wetting agent comprising a pyrophosphate. [Effects of the Invention]

[0011] The present invention provides a water-based ink composition for a felt-tip pen that has improved "handwriting drying properties" such that handwriting dries quickly. The present invention provides a water-based ink composition for a felt-tip pen that has contradictory properties, namely, improved "handwriting drying property" whereby handwriting dries quickly, and further improved "cap-off property" whereby writing can be carried out without any problems even after the felt-tip pen is left uncapped. DETAILED DESCRIPTION OF THE INVENTION

[0012] [Water-based ink composition for felt-tip pens] One embodiment of the aqueous ink composition for a felt-tip pen of the present invention is an aqueous ink composition for a felt-tip pen containing (A) water, (B) a colorant, (C) a styrene-(meth)acrylic acid-based resin, and (D) a polyoxyethylene alkyl ether surfactant and / or a polyoxyethylene alkyl phenyl ether surfactant. One embodiment of the aqueous ink composition for a felt-tip pen of the present invention is an aqueous ink composition for a felt-tip pen, which further contains (A) water, (B) a colorant, (C) a styrene-(meth)acrylic acid-based resin, (D) a polyoxyethylene alkyl ether surfactant and / or a polyoxyethylene alkyl phenyl ether surfactant, and (E) a wetting agent, wherein the wetting agent contains a pyrophosphate. The aqueous ink composition for a felt-tip pen of the present invention may further contain a wetting agent other than pyrophosphate, a water-soluble organic solvent, a water-dispersible resin, and other additives (preservatives, antifungal agents, etc.). Each component will be described in detail below.

[0013] <(A) Water> The aqueous ink composition for a felt-tip pen of the present invention contains (A) water. (A) Water functions as a solvent and / or dispersion medium for dissolving and / or dispersing the components of the aqueous ink composition for a felt-tip pen. Examples of water that can be used include tap water, purified water, distilled water, ion-exchanged water, and pure water. Preferably, pure water, ion-exchanged water, or distilled water is used.

[0014] The content of (A) water is not particularly limited. It can be, for example, 15% by mass or more, preferably 20% by mass or more, and more preferably 50% by mass or more, and can be, for example, 85% by mass or less, preferably 80% by mass or less, and more preferably 70% by mass or less, based on 100% by mass of the total amount of the aqueous ink composition for felt-tip pens. If the water content is less than 15% by mass, one or more of the following may occur: reduced handleability due to increased viscosity, poor writing such as smearing, and reduced storage stability. If the water content exceeds 85% by mass, one or more of the following may occur: a decrease in the concentration of the constituent components, resulting in a deterioration in color tone (lightening), and reduced drying speed of the writing.

[0015] <(B) Colorant> The aqueous ink composition for a felt-tip pen of the present invention contains a (B) colorant. The (B) colorant has the function of imparting a desired color tone to the writing of the aqueous ink composition for a felt-tip pen. As the (B) colorant, one or more of the various colorants that have dispersibility in the aqueous ink composition for a felt-tip pen, resistance properties such as light fastness and chemical resistance, and hiding power, etc., and that have conventionally been used in aqueous ink compositions for felt-tip pens, are used. As the colorant, for example, one or more of the various colorants that have conventionally been used in aqueous ink compositions for felt-tip pens, such as inorganic pigments, organic pigments, dyes, and colored resin spheres, are used.

[0016] Examples of inorganic pigments include one or more selected from the group consisting of carbon black, graphite, titanium oxide, zinc oxide, red iron oxide, yellow iron oxide, ultramarine, Prussian blue, metal powders such as aluminum powder and bronze powder, extender pigments such as talc, silica, alumina, mica and alumina silicate, fluorescent pigments, glass flakes, and luster pigments. Examples of organic pigments include at least one selected from the group consisting of color pigments such as phthalocyanine-based, azo-based, anthraquinone-based, quinacridone-based, isoindolinone-based, diketopyrrolopyrrole-based, dioxane-based, indigo-based, thioindigo-based, perinone-based, perylene-based, indolenone-based, and azomethine-based pigments, and fluorescent pigments. The dye is preferably a water-soluble dye, and examples thereof include one or more dyes selected from the group consisting of direct dyes, acid dyes, food dyes, basic dyes, and coloring dyes and fluorescent dyes such as anthraquinone-based, methine-based, carbonium-based, and metal complex salt-based dyes.

[0017] Colored resin spheres are spherical, irregular, hollow, flattened, or other resin spheres colored with one or more inorganic pigments, organic pigments, or dyes of any desired color tone. Examples of resin materials used to form the colored resin spheres include polyethylene, polypropylene, vinyl chloride, polymethacrylate, benzoguanamine, melamine resin, and nylon. The inorganic pigment, organic pigment, and dye that impart a color tone to the colored resin spheres may be one or more selected from the group consisting of the inorganic pigments, organic pigments, and dyes described above.

[0018] In the water-based ink composition for a felt-tip pen of the present invention, it is preferable to use a pigment such as an inorganic pigment or an organic pigment as the colorant (B). The volume average primary particle size of the pigment is not particularly limited and can be, for example, 10 nm or more, preferably 50 nm or more, more preferably 60 nm or more, and can be, for example, 250 nm or less, preferably 200 nm or less, more preferably 150 nm or less.

[0019] The content of the colorant (B) is not particularly limited. * a * b * L in color space * value, a * value and b * The content can be adjusted so that the color tone is such that the chromaticity values ​​of the respective pigments are any desired values. The total amount of the aqueous ink composition for a felt-tip pen is taken as 100% by mass, and the content can be, for example, 0.5% by mass or more, preferably 1.0% by mass or more, and more preferably 3.0% by mass or more, and can be, for example, 20.0% by mass or less, preferably 15.0% by mass or less, and more preferably 12.0% by mass or less. If the content of (B) colorant is less than 0.5% by mass, the color tone of the aqueous ink composition for a felt-tip pen may be too light, failing to achieve the desired color tone and resulting in poor color development. If the content of pigment is more than 20.0% by mass, the color tone of the ink composition may be too dark, failing to achieve the desired color tone.

[0020] <(C) Styrene-(meth)acrylic acid resin> The water-based ink composition for a felt-tip pen of the present invention contains (C) a styrene-(meth)acrylic acid-based resin. The (C) styrene-(meth)acrylic acid-based resin improves the dispersibility of constituent components such as pigments in the water-based ink composition for a felt-tip pen, imparts dispersion stability, and imparts compatibility with solvents. The (C) styrene-(meth)acrylic acid-based resin also functions as a vehicle and fixing agent for forming a coating film of the water-based ink composition for a felt-tip pen.

[0021] The (C) styrene-(meth)acrylic acid resin is a resin obtained by polymerizing a monomer component containing styrene and (meth)acrylic acid as essential monomer components, and optionally containing other monomers. Examples of the other monomers include one or more selected from the group consisting of (meth)acrylic acid alkyl ester compounds, styrene compounds (alkylstyrene, halogenated styrene, vinyl benzoate, etc.), olefin compounds, hydroxyl group-containing (meth)acrylate compounds, amino group-containing (meth)acrylate compounds, (meth)acrylamide compounds, and polyfunctional (meth)acrylate compounds.

[0022] The weight average molecular weight of the (C) styrene-(meth)acrylic acid-based resin is not particularly limited and can be, for example, 2,000 or more, preferably 3,000 or more, more preferably 5,000 or more, and can be, for example, 50,000 or less, preferably 30,000 or less, more preferably 15,000 or less. The acid value of the (C) styrene-(meth)acrylic acid-based resin is not particularly limited and can be, for example, 50 mgKOH / g or more, preferably 100 mgKOH / g or more, and can be, for example, 500 mgKOH / g or less, preferably 300 mgKOH / g or less.

[0023] The (C) styrene-(meth)acrylic acid-based resin may be a synthesized product or a commercially available product, such as one or more of the Hi-Los series (X-1, VS1063, RS-1191, etc.; manufactured by Seiko PMC Corporation) and the Joncryl series (67, 611, 678, 682, 683, 690, etc.; manufactured by BASF).

[0024] The content of the (C) styrene-(meth)acrylic acid-based resin is not particularly limited. It can be, for example, 0.5% by mass or more, preferably 1.0% by mass or more, and for example, 5.0% by mass or less, preferably 3.0% by mass or less, based on the total amount of the water-based ink composition for felt-tip pens (100% by mass). If the content of the (C) styrene-(meth)acrylic acid-based resin is less than 0.5% by mass, the dispersibility of the components in the water-based ink composition for felt-tip pens may decrease. If the content of the (C) styrene-(meth)acrylic acid-based resin is more than 5.0% by mass, the viscosity of the water-based ink composition for felt-tip pens may become too high, resulting in smearing of handwriting.

[0025] <(D) Polyoxyethylene alkyl ether surfactant and / or polyoxyethylene alkyl phenyl ether surfactant> The aqueous ink composition for a felt-tip pen of the present invention contains (D) a polyoxyethylene alkyl ether surfactant and / or a polyoxyethylene alkyl phenyl ether surfactant. (D) The polyoxyethylene alkyl ether surfactant and / or polyoxyethylene alkyl phenyl ether surfactant has the functions of improving the wettability and aiding dispersion of the pigment in the aqueous ink composition for a felt-tip pen, and adjusting the surface tension of the aqueous ink composition for a felt-tip pen.

[0026] The polyoxyethylene alkyl ether surfactant is represented by the formula (I): [ka] It is a compound having a structure represented by the following formula: One or more types of polyoxyethylene alkyl ether surfactants can be used. In formula (I), R a is an alkyl group having 6 to 24 carbon atoms, and examples thereof include a hexyl group, an octyl group, a nonyl group, a decyl group, a dodecyl group, a lauryl group (dodecyl group), a myristyl group (tetradecyl group), a cetyl group (hexadecyl group), a stearyl group (octadecyl group), and a behenyl group. In formula (I), n is an integer of 2 or more and 100 or less, and can be, for example, 2 or more and 50 or less, and preferably 2 or more and 30 or less.

[0027] Commercially available polyoxyethylene alkyl ether surfactants may be used, such as the Noigen series (Dai-ichi Kogyo Seiyaku Co., Ltd.), the BT series (Nikko Chemicals Co., Ltd.), the Softanol series (Nippon Shokubai Co., Ltd.), Dispanol (NOF Corporation), the Nonipol series (Sanyo Chemical Industries, Ltd.), the D-series (Takemoto Yushi Co., Ltd.), the P-series (Takemoto Yushi Co., Ltd.), the EMALEX DAPE series (Nippon Emulsion Co., Ltd.), and the Pegnol series (Toho Chemical Industry Co., Ltd.).

[0028] The polyoxyethylene alkylphenyl ether surfactant has the formula (II): [ka] It is a compound having a structure represented by the following formula: One or more types of polyoxyethylene alkyl phenyl ether surfactants can be used. In formula (II), R b is an alkyl group having 6 to 24 carbon atoms or an optionally substituted phenyl group, and examples thereof include a hexyl group, an octyl group, a nonyl group, a decyl group, a dodecyl group, a lauryl group (a dodecyl group), a myristyl group (a tetradecyl group), a cetyl group (a hexadecyl group), a stearyl group (an octadecyl group), a behenyl group, a styryl group, and a benzyl group. In formula (II), m is an integer of 1 or more and 5 or less, for example, 1 or more and 3 or less, and preferably 1 or more and 2 or less. In formula (II), n is an integer of 2 or more and 100 or less, and can be, for example, 2 or more and 70 or less, and preferably 2 or more and 50 or less.

[0029] Commercially available polyoxyethylene alkylphenyl ether surfactants may be used, such as the BLAUNON series (Aoki Oil & Fat Industries), the Nonal series (Toho Chemical Industry Co., Ltd.), the Triton series (Sigma-Aldrich Japan), the Noigen series (Dai-ichi Kogyo Seiyaku Co., Ltd.), the Eleminol series (Sanyo Chemical Industries Co., Ltd.), and the Emulgen series (Kao Corporation).

[0030] The HLB value of (D) polyoxyethylene alkyl ether surfactant and / or polyoxyethylene alkyl phenyl ether surfactant is not particularly limited. For example, the HLB value can be 8.0 or more, preferably 8.5 or more, and for example, the HLB value can be 16.0 or less, preferably 15.0 or less. When (D) polyoxyethylene alkyl ether surfactant and / or polyoxyethylene alkyl phenyl ether surfactant contains two or more surfactants, the HLB value is preferably the HLB value of the composition as a whole.

[0031] The content of the (D) polyoxyethylene alkyl ether surfactant and / or polyoxyethylene alkyl phenyl ether surfactant is not particularly limited. It can be, for example, 0.01% by mass or more, preferably 0.05% by mass or more, and more preferably 0.75% by mass or more, based on 100% by mass of the total amount of the aqueous ink composition for felt-tip pens. It can be, for example, 5.0% by mass or less, preferably 3.0% by mass or less, and more preferably 2.0% by mass or less. If the content of the (D) polyoxyethylene alkyl ether surfactant and / or polyoxyethylene alkyl phenyl ether surfactant is less than 0.01% by mass, problems may arise in terms of improving pigment wettability, improving dispersibility, and adjusting surface tension. If the content of the (D) polyoxyethylene alkyl ether surfactant and / or polyoxyethylene alkyl phenyl ether surfactant is more than 5.0% by mass, problems may arise in terms of improving ink drying properties and ease of handling.

[0032] <(E) Wetting agent> The water-based ink composition for a felt-tip pen of the present invention may further contain (E) a wetting agent. Examples of the (E) wetting agent include one or more selected from the group consisting of pyrophosphates such as sodium pyrophosphate, potassium pyrophosphate, lithium pyrophosphate, calcium pyrophosphate, calcium dihydrogen pyrophosphate, strontium pyrophosphate, barium pyrophosphate, iron pyrophosphate, copper pyrophosphate, zinc pyrophosphate, silver pyrophosphate, and ammonium pyrophosphate; urea compounds such as urea, thiourea, ethylene urea, dimethyl urea, diethyl thiourea, ethyl urea, methyl urea, and ethylene thiourea; glycerin compounds such as glycerin, diglycerin, and triglycerin; sorbitol, mannitol, sucrose, glucose, and reduced starch hydrolysates.

[0033] In addition to (A) to (D), the aqueous ink composition for a felt-tip pen of the present invention preferably contains (E) a wetting agent containing a pyrophosphate salt. This allows the composition to achieve both the contradictory properties of "handwriting drying property," in which handwriting dries quickly, and "cap-off property," in which writing can be continued without any problems even after the felt-tip pen has been left uncapped.

[0034] The content of pyrophosphate can be, for example, 10.0% by mass or less, preferably 8.0% by mass or less, and more preferably 7.0% by mass or less, based on 100% by mass of the total amount of the aqueous ink composition for felt-tip pens. If the content of pyrophosphate exceeds 10.0% by mass, the fluidity of the aqueous ink composition for felt-tip pens may decrease, causing smearing of handwriting. In the present invention, when the aqueous ink composition for a felt-tip pen contains a pyrophosphate, the lower limit of the content can be set to 0.1% by mass, preferably 0.5% by mass, which makes it possible to achieve both the contradictory properties of "writing drying property" and "cap-off property."

[0035] The aqueous ink composition for a felt-tip pen of the present invention may contain urea as a humectant. In addition to (A) to (D), the aqueous ink composition for a felt-tip pen preferably contains (E) a humectant containing urea as a humectant. This makes it possible to inhibit the aqueous ink composition for a felt-tip pen from drying while maintaining the "handwriting drying property" that allows handwriting to dry quickly.

[0036] The urea content can be, for example, 20.0% by mass or less, preferably 15.0% by mass or less, based on 100% by mass of the total amount of the aqueous ink composition for felt-tip pens. If the urea content exceeds 20.0% by mass, there is a risk of urea precipitating in the aqueous ink composition for felt-tip pens. In the present invention, when the aqueous ink composition for a felt-tip pen contains urea, the lower limit of the urea content can be 1.0 mass %, preferably 2.0 mass %, and more preferably 5.0 mass %, which makes it possible to achieve both the contradictory properties of "good handwriting drying property" and inhibition of drying of the ink at the pen tip.

[0037] <(F) Water-soluble organic solvent> The aqueous ink composition for a felt-tip pen of the present invention may contain (F) a water-soluble organic solvent. By containing (F) a water-soluble organic solvent in addition to (A) to (D), the aqueous ink composition for a felt-tip pen can suppress drying of the aqueous ink composition for a felt-tip pen and improve wettability while maintaining "handwriting drying properties" that allow handwriting to dry quickly.

[0038] The (F) water-soluble organic solvent is an organic solvent having 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 uniformly miscible in any proportion. Examples include one or more solvents selected from the group consisting of monoalcohol solvents, polyhydric alcohol solvents, polyhydric alcohol alkyl ether solvents, ester solvents, nitrogen-containing compound solvents, ketone solvents, ether solvents, etc. Among these, one or more solvents selected from the group consisting of monoalcohol solvents, polyhydric alcohol solvents, and polyhydric alcohol alkyl ether solvents are preferred.

[0039] Examples of the monoalcohol solvent include one or more selected from the group consisting of methanol, ethanol, n-propanol, n-butanol, n-pentanol, n-hexanol, n-octanol, cyclopentanol, cyclohexanol, and the like.

[0040] Examples of polyhydric alcohol solvents include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 1,2-hexanediol, 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-octanediol, diethylene glycol, triethylene glycol, dipropylene glycol, butylene glycol, dibutylene glycol, trimethylolpropane, and pentaerythritol.

[0041] Examples of polyhydric alcohol alkyl ether solvents include mono(C1-C5) alkyl ethers of the above polyhydric alcohols and poly(C1-C5) alkyl ethers of the above polyhydric alcohols. For example, ethylene glycol monomethyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monoisobutyl ether, diethylene glycol monomethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, diethylene glycol diethyl ether, diethylene glycol monopropyl ether, diethylene glycol monobutyl ether, diethylene glycol monopentyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol monopropyl ether, triethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, tetraethylene glycol monopropyl ether, tetraethylene glycol monobutyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ... and at least one selected from the group consisting of ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monopropyl ether, dipropylene glycol monomethyl 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, and tetraethylene glycol diethyl ether.

[0042] The (F) water-soluble organic solvent is preferably at least one selected from the group consisting of polyhydric alcohol solvents and polyhydric alcohol alkyl ether solvents, more preferably at least one selected from the group consisting of ethylene glycol, propylene glycol, diethylene glycol, trimethylolpropane, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, and 1,6-hexanediol, and even more preferably at least one selected from the group consisting of ethylene glycol, glycerin, ethylene glycol monobutyl ether, and glycerin.

[0043] The content of the (F) water-soluble organic solvent can be, for example, 30.0% by mass or less, preferably 25.0% by mass or less, and more preferably 20.0% by mass or less, based on 100% by mass of the total amount of the water-based ink composition for a felt-tip pen. If the content of the (F) water-soluble organic solvent exceeds 30.0% by mass, the dispersibility of the components of the water-based ink composition for a felt-tip pen may decrease. In the present invention, when the aqueous ink composition for a felt-tip pen contains (F) a water-soluble organic solvent, the lower limit of the content can be 1.0 mass %, preferably 2.0 mass %, and more preferably 5.0 mass %, which makes it possible to simultaneously achieve the contradictory properties of "writing drying property," i.e., inhibiting drying of the aqueous ink composition for a felt-tip pen, and improving wettability.

[0044] <(G) Water-dispersible resin> The aqueous ink composition for a felt-tip pen of the present invention may contain (G) a water-dispersible resin other than (C) a styrene-(meth)acrylic acid-based resin. By containing (G) a water-dispersible resin in addition to (A) to (D), the aqueous ink composition for a felt-tip pen can be used to write on a writing surface with a felt-tip pen, and when the solvent evaporates, the handwriting can be reliably fixed on the writing surface. The (G) water-dispersible resin can be one that is dispersed in a solvent in advance, or one in the form of a resin emulsion that has film-forming properties at room temperature.

[0045] (G) The water-dispersible resin may be, for example, one or more selected from the group consisting of acrylic resins, styrene-(meth)acrylic acid ester resins, styrene-maleic acid resins, vinyl acetate resins, urethane resins, and the like.

[0046] The content of the (G) water-dispersible resin can be, for example, 8.0% by mass or less, preferably 5.0% by mass or less, based on 100% by mass of the total amount of the aqueous ink composition for felt-tip pens. If the content of the (G) water-dispersible resin exceeds 8.0% by mass, the viscosity of the aqueous ink composition for felt-tip pens will increase, which may result in an inappropriate amount of ink flow during writing and cause smearing or the like in handwriting. In the present invention, when the aqueous ink composition for a felt-tip pen contains the water-dispersible resin (G), the lower limit of the content can be set to 0.5 mass %, preferably 1.0 mass %, and more preferably 1.5 mass %, which can make the amount of ink flowing out during writing appropriate and improve the scratch resistance of handwriting.

[0047] <(H) Other Additives> The aqueous ink composition for a felt-tip pen of the present invention may optionally contain "(H) other additives" in addition to the essential components (A) to (D) and the optional components (E) to (G). The (H) other additives are not particularly limited as long as they are other than components (A) to (G) and are used in aqueous ink compositions for felt-tip pens. For example, one or more additives selected from the group consisting of preservatives, mildew inhibitors, pH adjusters, thickening inhibitors, surfactants other than (D), water-soluble resins other than (C), wetting agents, lubricants, antifoaming agents, leveling agents, ultraviolet absorbers, infrared absorbers, antioxidants, fluorescent brighteners, viscosity adjusters (thickeners), lubricants, and non-water-soluble organic solvents may be used in an appropriate amount as needed.

[0048] Examples of the antiseptic and antifungal agent include one or more antiseptics selected from the group consisting of benzoisothiazoline-based antiseptic and antifungal agents, pentachlorophenol-based antiseptic and antifungal agents, cresol-based antiseptic and antifungal agents, propylene glycol-based antiseptic and antifungal agents, and iodine-based antiseptic and antifungal agents.

[0049] Examples of pH adjusters include one or more selected from the group consisting of inorganic bases (sodium hydroxide, potassium hydroxide, sodium carbonate, sodium acetate, ammonia (water), etc.) and organic bases (water-soluble amine compounds, etc.).

[0050] Examples of the lubricant include one or more selected from the group consisting of metal soaps, polyalkylene glycol fatty acid esters, ethylene oxide-added cationic surfactants, phosphate ester surfactants, N-acylamino acid surfactants, dicarboxylic acid surfactants, β-alanine surfactants, 2,5-dimercapto-1,3,4-thiadiazole, salts and oligomers thereof, 3-amino-5-mercapto-1,2,4-triazole, thiocarbamate, dimethyldithiocarbamate, α-lipoic acid, condensates of N-acyl-L-glutamic acid and L-lysine, and salts thereof.

[0051] Examples of the thickening inhibitor include one or more selected from the group consisting of oligomers of N-vinyl-2-pyrrolidone, oligomers of N-vinyl-2-piperidone, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, ε-caprolactam, and oligomers of N-vinyl-ε-caprolactam.

[0052] <Viscosity> The viscosity of the aqueous ink composition for a felt-tip pen of the present invention is not particularly limited and can be set appropriately. In particular, the viscosity of the aqueous ink composition for a felt-tip pen is preferably 100 mPa·s or less. For example, it can be 1.0 mPa·s or more, preferably 2.0 mPa·s or more, more preferably 3.0 mPa·s or more, and can be set within the range of, for example, 35.0 mPa·s or less, preferably 15.0 mPa·s or less, more preferably 6.0 mPa·s or less (as measured with an E-type rotational viscometer (e.g., a TVE-type viscometer manufactured by Toki Sangyo Co., Ltd., 1°34' cone, 50 rpm)). If the viscosity of the aqueous ink composition for a felt-tip pen is less than 1.0 mPa·s, excessive ink flow from the tip of the writing instrument may occur, making it difficult to form accurate handwriting. If the viscosity exceeds 100 mPa·s, the viscosity may become too high and the ink may not flow out from the tip of the writing instrument, and problems may arise in terms of ink handling, sedimentation stability, blurring of handwriting, and manufacturing costs.

[0053] <Method for producing water-based ink composition for felt-tip pen> The method for producing the water-based ink composition for a felt-tip pen of the present invention is not particularly limited, and any known method for producing a water-based ink composition for a felt-tip pen can be used. For example, all of the components constituting the water-based ink composition for a felt-tip pen can be placed in a container and mixed, stirred, and dispersed using a mixing / stirring device such as a ball mill, bead mill, roll mill, homogenizer, high-pressure homogenizer, Henschel mixer, homomixer, propeller stirrer, kneader, or dissolver to prepare the water-based ink composition for a felt-tip pen.

[0054] For example, some of the components of the aqueous ink composition for a felt-tip pen, such as water, colorant (pigment), water-soluble organic solvent, styrene-(meth)acrylic acid resin, and pH adjuster, are placed in a container and mixed, stirred, and dispersed using a ball mill, bead mill, roll mill, homogenizer, or high-pressure homogenizer to produce a dispersion.The remaining components are then added to the resulting dispersion, and mixed and stirred using a Henschel mixer, homomixer, propeller stirrer, kneader, or dissolver to produce the aqueous ink composition for a felt-tip pen. When preparing the water-based ink composition for a felt-tip pen, coarse particles, gas, and bubbles may be removed by filtration, centrifugation, degassing, etc. When preparing the water-based ink composition for a felt-tip pen, means such as heating, cooling, pressurization, decompression, and inert gas substitution may also be employed. Furthermore, an aging step may be carried out after preparation of the water-based ink composition for a felt-tip pen.

[0055] <Water-based sign pen> Examples of water-based felt-tip pens prepared using the water-based ink composition for felt-tip pens of the present invention include writing instruments that have a pen tip made of a fiber bundle core, a sintered core, or a plastic core, and that are provided with an ink reservoir in the main body, and that supply ink from the ink reservoir to the pen tip by capillary action, enabling writing. The ink reservoir may be a so-called core made of felt or fiber bundle, or may be one that stores ink directly within the main body. In the present invention, the ink pen may be either a core-type water-based felt-tip pen that uses a core as an ink reservoir, or a non-core-type water-based felt-tip pen (free-ink type water-based felt-tip pen) that stores the ink directly within the body. Of these, a core-type water-based felt-tip pen is preferred. [Example]

[0056] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "%" means "% by mass" and "parts" means "parts by mass." The numbers in Tables 1 to 3 indicate the blend amounts (parts by mass).

[0057] <Ingredients> The components constituting the water-based ink compositions for felt-tip pens described in Examples 1 to 20 and Comparative Examples 1 to 3 were as follows. Water: Ion-exchanged water Colorant 1: Pigment Black 7 Colorant 2: Pigment Red 267 Colorant 3: Pigment Blue 15:3 St-(m)Ac resin 1: styrene-(meth)acrylic acid resin (acid value 215 mgKOH / g, glass transition temperature 85°C) St-(m)Ac resin 2: styrene-(meth)acrylic acid resin (acid value 110 mgKOH / g, glass transition temperature 52°C) Surfactant 1: POE alkyl ether (HLB=10.8) Surfactant 2: POE alkyl ether (HLB=13.8) Surfactant 3: POE alkyl phenyl ether (HLB=11.8) Surfactant 4: POE alkyl phenyl ether phosphate ester (HLB=10.5) Humectant 1: Glycerin Wetting agent 2: Urea Wetting agent 3: Potassium pyrophosphate Water-soluble organic solvent 1: Ethylene glycol Water-soluble organic solvent 2: Ethylene glycol monobutyl ether pH adjuster 1: 28% ammonia water pH adjuster 2: Sodium hydroxide Water-dispersible resin: Acrylic resin emulsion (solid content 40% by mass, minimum film-forming temperature 220°C) Antifungal agent: 3-iodo-2-propynyl N-butylcarbamate Preservative: 1,2-benzisothiazolin-3-one

[0058] [Examples 1 to 20 and Comparative Examples 1 to 3] <Preparation of Water-Based Ink Composition for Sign Pen> The constituent components of the water-based ink composition for a felt-tip pen shown in Tables 1 to 3 were mixed in a stirrer, and coarse particles in the ink were removed using a high-speed centrifuge to prepare a water-based ink composition for a felt-tip pen.

[0059] <Preparation of water-based marker pen> A tip was attached to a pen body (a core-type felt-tip pen manufactured by Sakura Color Products Co., Ltd.), and a cap was attached. The core was filled with each of the water-based ink compositions for felt-tip pens of Examples 1 to 20 and Comparative Examples 1 to 3, which were then inserted into the pen body. A tail plug was then attached to prepare a water-based felt-tip pen.

[0060] <Evaluation> The water-based ink compositions for felt-tip pens of Examples 1 to 20 and Comparative Examples 1 to 3 were evaluated for writing drying properties and cap-off properties as follows.

[0061] (Handwriting dryness) A 3 cm straight line was written on high-quality paper in one second under an environment of 20°C and 65% RH, and after a certain time had passed since writing, the end point of the line was rubbed with a finger and visually observed to see if the aqueous ink composition for felt-tip pens had spread around the handwriting. The time until the aqueous ink composition for felt-tip pens no longer spread around the handwriting was taken as the drying time of the handwriting, and the handwriting drying property was evaluated based on the drying time of the handwriting according to the following criteria. The results are shown in Tables 1 to 3. In the present invention, A and B are acceptable. A: The ink dries within 5 seconds. B: The drying time of the handwriting is more than 5 seconds but less than 7 seconds. C: The drying time of the writing is more than 7 seconds.

[0062] (Cap-off property) After leaving the water-based felt-tip pen with the cap off for 7 hours in an environment of 20°C and 65% RH, three 10 cm straight lines were written on high-quality paper, each line taking 3 seconds and 9 seconds, and the handwriting was evaluated according to the following criteria. The results are shown in Table 3. In the present invention, S, A, and B are acceptable. S: Normal handwriting was obtained from the first writing. A: Normal handwriting was obtained from the second writing. B: Normal handwriting was obtained from the third writing. C: Normal handwriting was not obtained by the third attempt.

[0063] [Table 1]

[0064] [Table 2]

[0065] [Table 3]

[0066] It can be seen from Tables 1 and 2 that the aqueous ink compositions for felt-tip pens of the present invention according to Examples 1 to 20, which contain (A) water, (B) a colorant, (C) a styrene-(meth)acrylic acid resin, and (D) a polyoxyethylene alkyl ether surfactant and / or a polyoxyethylene alkyl phenyl ether surfactant, are excellent in handwriting drying properties. On the other hand, it can be seen that the aqueous ink compositions for felt-tip pens according to Comparative Examples 1 to 3, which do not contain (D) a polyoxyethylene alkyl ether surfactant and / or a polyoxyethylene alkyl phenyl ether surfactant, are not satisfactory in terms of handwriting drying properties.

[0067] Table 3 shows that the aqueous ink compositions for felt-tip pens of the present invention according to Examples 15 to 20, which contain (A) water, (B) a colorant, (C) a styrene-(meth)acrylic acid resin, and (D) a polyoxyethylene alkyl ether surfactant and / or a polyoxyethylene alkyl phenyl ether surfactant, and further contain (E) a pyrophosphate as a wetting agent, have excellent writing drying properties and cap-off properties.

Claims

1. (A) water, (B) a colorant, (C) a styrene-(meth)acrylic acid-based resin, and (D) polyoxyethylene alkyl ether surfactant and / or polyoxyethylene alkyl phenyl ether surfactant, A water-based ink composition for a felt-tip pen, comprising:

2. 2. The water-based ink composition for a felt-tip pen according to claim 1, further comprising (E) a wetting agent, the wetting agent containing a pyrophosphate.

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