Water-based ink composition for writing implements and writing implements containing the same

Abstract

To provide an aqueous ink composition for writing utensils which suppresses localization by floating or precipitating a coloring agent in an ink composition to make handwriting dark or pale, and enables formation of good handwriting excellent in color development property without making the handwriting pale when stimulation such as vibration from the outside is applied to a writing utensil storing an ink composition using a coloring agent having a large specific gravity in an erected state, and the writing utensil is stored over a long period of time, and a writing utensil storing the same.SOLUTION: An aqueous ink composition for writing utensils contains a coloring agent selected from a pigment or resin particles, and a vehicle containing at least water, a cationic polymer having a specific structure and an acrylic polymer dispersant.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an aqueous ink composition for a writing instrument and a writing instrument containing the same. More specifically, the present invention relates to an aqueous ink composition for a writing instrument that can suppress differences in shading in handwriting and produce good handwriting with excellent color development, and a writing instrument containing the same. [Background technology]

[0002] Inks using water as the primary solvent (water-based inks) have been known for some time and are widely used due to their low odor and high safety. Furthermore, water-based pigment inks, which use pigments as ink colorants, are widely used due to their excellent lightfastness and water resistance. Pigments typically have unstable dispersion stability in water or aqueous media, and the pigments may float or settle and become localized in the ink. Therefore, ink compositions have been disclosed that use various dispersants and additives to improve the dispersion stability of pigments in water-based inks (see, for example, Patent Documents 1 to 3). Patent Document 1 discloses a water-based ink composition for writing instruments that uses a reversible thermochromic microcapsule pigment and a vehicle comprising water, a polymer flocculant, a dispersant, and the like. Patent Document 2 discloses an aqueous pigment ink composition for writing implements, which contains a pigment, a dispersant, water, a water-soluble solvent, and an alkylpyrrolidone having an alkyl group with 4 to 20 carbon atoms. Patent Document 3 discloses an aqueous ink composition comprising a pigment, an aqueous medium, and a copolymer of an N-vinylpyrrolidone derivative and an acrylic acid derivative or a methacrylic acid derivative as a dispersant. The above-mentioned aqueous ink composition (aqueous pigment ink composition) can stably disperse the pigment in the ink composition by using a dispersant or by using a dispersant in combination with a specific additive, and therefore a writing instrument containing such an ink composition can suppress darkening or lightening of handwriting. However, it is difficult to completely suppress floating or settling of the pigment with the above-mentioned ink composition, and in particular, when a writing instrument containing an ink composition using a pigment with a high specific gravity is subjected to external stimuli such as vibration with the writing tip facing upward (upright state) or is stored for a long period of time, the pigment may settle, preventing the ink from being ejected uniformly from the writing tip, and resulting in lighter handwriting. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 11-335613 [Patent Document 2] Japanese Patent Application Publication No. 8-283646 [Patent Document 3] Japanese Patent Application Publication No. 9-59554 Summary of the Invention [Problem to be solved by the invention]

[0004] The present invention aims to provide a water-based ink composition for a writing instrument that can prevent a colorant from floating up or settling and becoming localized in the ink composition, causing handwriting to become darker or lighter in color, and a writing instrument containing the same. [Means for solving the problem]

[0005] The present invention provides A reversible thermochromic microcapsule pigment encapsulating a reversible thermochromic composition comprising at least (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction medium that controls the color-forming reaction of the components (a) and (b). and at least water and a compound represented by the following formula (1) to ( 4 ) , and Eq. (32) The present invention provides a water-based ink composition for a writing instrument, which comprises a vehicle containing a cationic polymer selected from the group consisting of: and an acrylic polymer dispersant. [ka] (In the formula, n1 represents an integer of 0 or 1, X1 represents hydrochloric acid, amidosulfuric acid, or acetic acid, and n represents a natural number. The mass average molecular weight is in the range of 500 to 200,000.) [ka] (In the formula, n2a and n2b each independently represent an integer of 0 or 1, and X 2a and X 2b each independently represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. The mass average molecular weight is in the range of 500 to 200,000. [ka] (In the formula, n3a and n3b ​​each independently represent an integer of 0 or 1, and X 3a and X 3b each independently represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. The mass average molecular weight is in the range of 500 to 200,000. [ka] (wherein R1 is a hydrogen atom) Child n4 represents an integer of 0 or 1, X4 represents hydrochloric acid, amidosulfuric acid, or acetic acid, and n represents a natural number. The mass average molecular weight is in the range of 500 to 200,000. [ka] (In the formula, R 4 represents a linear or branched alkyl group having 1 to 3 carbon atoms, a linear or branched alkoxy group having 1 to 3 carbon atoms, or an amino group, and m and n each independently represent a natural number. Furthermore, n2a and n2b are integers of 0 or 1, or n3a and n3b ​​are integers of 0 or 1; X 2a and X 2b are the same, or X 3a and X 3bthe mass ratio of the cationic polymer to the acrylic polymer dispersant is 1:2.5 to 1:16; the viscosity at 20°C at a rotation speed of 30 rpm as measured by a BL type rotational viscometer is 1 to 20 mPa·s; Reversible thermochromic microcapsule pigment The average particle size is in the range of 0.01 to 5 μm. ,before The requirements are that the component (c) is in the range of 60 to 90 mass % of the total amount of the reversible thermochromic composition, that the mass average molecular weight is 250 or more, and that the specific gravity of the reversibly thermochromic microencapsulated pigment in a fully colored state at 20°C when water is used as a reference substance is 1.05 to 1.20, that the acrylic polymer dispersant is a comb-shaped polymer dispersant having a carboxy group in the side chain, and that the vehicle contains a specific gravity adjuster consisting of an oxyacid of a Group 6 element having an atomic weight of 90 to 185 or a salt thereof. Further requirements include a writing instrument containing the water-based ink composition for a writing instrument, the writing instrument having a marking pen tip made of a resin-processed body or a resin-molded body having capillary gaps formed therein, a marking pen having an ink occlusion body made of a fiber bundle built into the barrel of the writing instrument and having the ink occlusion body and the marking pen tip connected together, the ink occlusion body being impregnated with the water-based ink composition for a writing instrument, and a friction member that discolors writing made with the writing instrument due to frictional heat. [Effects of the Invention]

[0006] The present invention can provide an ink composition for a writing instrument and a writing instrument that can produce good handwriting with excellent color development, in which the colorant in the ink composition is prevented from floating up or settling and becoming localized, resulting in darkening or lightening of handwriting, and in particular, when a writing instrument containing an ink composition that uses a colorant with a high specific gravity is subjected to external stimuli such as vibration in an upright position or is stored for a long period of time, the handwriting does not lighten. [Brief explanation of the drawings]

[0007] [Figure 1]1 is a graph illustrating the hysteresis characteristics in the color density-temperature curve of a reversibly thermochromic composition that is heat-discolorable. [Figure 2] 1 is a graph illustrating the hysteresis characteristics in the color density-temperature curve of a heat-discolorable, reversible thermochromic composition having color memory properties. [Figure 3] 1 is a graph illustrating the hysteresis characteristics in the color density-temperature curve of a reversibly thermochromic composition that develops color over time. [Figure 4] 1 is an explanatory diagram showing an embodiment of a writing instrument of the present invention. [Figure 5] 10A and 10B are explanatory diagrams showing another embodiment of the writing instrument of the present invention. [Figure 6] 6 is a cross-sectional view taken along line AA of the resin-processed pen element of the writing implement of FIG. 5. [Figure 7] 10A and 10B are explanatory diagrams showing another embodiment of the writing instrument of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0008] The aqueous ink composition for a writing instrument of the present invention (hereinafter sometimes referred to as "aqueous ink composition," "ink composition," or "ink") comprises a colorant selected from pigments or resin particles, and a vehicle containing at least water, a cationic polymer selected from the above formulas (1) to (5), and an acrylic polymer dispersant. Each component constituting the aqueous ink composition of the present invention will be described below.

[0009] The water-based ink composition of the present invention contains a pigment or resin particles as a colorant. The pigment is not particularly limited as long as it can be dispersed in an aqueous medium, and examples thereof include inorganic pigments, organic pigments, photoluminescent pigments, fluorescent pigments, and phosphorescent pigments. Further examples thereof include microencapsulated pigments in which the above-mentioned pigments, dyes, or functional materials such as thermochromic materials and photochromic materials are encapsulated in microcapsules. Examples of the resin particles include resin particles containing a pigment, a dye, or a functional material such as a thermochromic material or a photochromic material.

[0010] Examples of inorganic pigments include carbon black, rutile or anatase titanium oxide, zinc oxide, iron oxide, yellow iron oxide, red iron oxide, and ultramarine.

[0011] Examples of organic pigments include azo pigments, phthalocyanine pigments, quinacridone pigments, perylene pigments, perinone pigments, isoindolinone pigments, isoindoline pigments, dioxazine pigments, thioindigo pigments, anthraquinone pigments, quinophthalone pigments, diketopyrrolopyrrole pigments, threne pigments, indigo pigments, phthalone pigments, methine azomethine pigments, and metal complex pigments.

[0012] It is also possible to use water-dispersed pigments that have been finely and stably dispersed in an aqueous medium in advance using a surfactant or resin. Specific examples of water-dispersible pigments include CI Pigment Blue 15:3B (manufactured by Sanyo Dye Co., Ltd., product name: Sandye Super Blue GLL-E (solid content: 24%)), CI Pigment Red 146 (manufactured by Sanyo Dye Co., Ltd., product name: Sandye Super Pink FBL (solid content: 21.5%)), CI Pigment Yellow 81 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., product name: TC Yellow FG (solid content: approximately 30%)), and CI Pigment Red 220 / 166 (manufactured by Dainichiseika Color & Chemicals Mfg. Co., Ltd., product name: TC Red FG (solid content: approximately 35%)). Examples of resins for dispersing pigments include polyamide, polyurethane, polyester, epoxy resin, melamine resin, phenolic resin, silicone resin, polyvinyl alcohol, polyvinylpyrrolidone, polyvinyl acetate, polyvinyl chloride, polyvinylidene chloride, polystyrene, acrylic acid resin, maleic acid resin, gum arabic, cellulose, dextran, casein, and derivatives thereof, and copolymers of the above-mentioned resins.

[0013] Examples of luster pigments include metallic luster pigments in which the surface of a core substance such as glass flakes is coated with gold, silver, or the like; pearl pigments in which the surface of a core substance such as natural mica, synthetic mica, or flaky aluminum oxide is coated with a metal oxide such as titanium oxide; cholesteric liquid crystal pigments; metal powder pigments; metallic pigments obtained by peeling off a metal vapor-deposited film of aluminum or the like formed on a substrate such as a film; and metallic pigments in which a metal vapor-deposited film of aluminum or the like is formed on a colorless, transparent, or colored transparent film and then powdered.

[0014] Examples of fluorescent pigments include fine particle fluorescent pigments of synthetic resins in which various fluorescent dyes are solid-dissolved in a resin matrix.

[0015] Any general-purpose phosphorescent pigment can be used as long as it has the property of absorbing and storing light from the sun, electric lamps, etc., and gradually releasing and emitting light in the dark (this is called afterglow). Examples of phosphorescent pigments include CaS / Bi-based, CaSrS / Bi-based, ZnS / Cu-based, ZnCdS / Cu-based, and SrAl2O4 / rare earth metal-based pigments.

[0016] The above-mentioned pigments can be used alone or in a suitable mixture of two or more, and are preferably blended in an amount of 1 to 50% by mass, more preferably 5 to 40% by mass, and even more preferably 10 to 35% by mass, based on the total amount of the ink composition. If the blending ratio of the pigment exceeds 50% by mass, the ink dischargeability of the writing instrument containing the ink composition decreases, and writing performance is likely to be impaired. On the other hand, if the blending ratio is less than 1% by mass, it becomes difficult to obtain a writing density suitable for the writing instrument. When the above pigments are used as colorants, a pigment dispersant can be used as needed. Examples of pigment dispersants include anionic and nonionic surfactants, anionic polymers such as polyacrylic acid and styrene acrylic acid, and nonionic polymers such as PVP and PVA.

[0017] The pigments applicable to the present invention also include microencapsulated pigments in which pigments, dyes, or functional materials such as thermochromic materials and photochromic materials are encapsulated in microcapsules. By encapsulating the pigments, dyes, functional materials, etc. in microcapsules, they are isolated and protected from the external environment, and the light resistance and water resistance of the encapsulated materials can be improved.

[0018] Examples of microcapsule pigments encapsulating a pigment or dye include microcapsule pigments encapsulating a colored body obtained by dispersing or dissolving a pigment or dye in an oil medium. As the pigment, the above-mentioned inorganic pigments, organic pigments, glitter pigments, fluorescent pigments, phosphorescent pigments, etc. can be used. As the dye, conventionally known oil-soluble dyes, disperse dyes, etc. can be used.

[0019] Examples of oil-soluble dyes include CI Solvent Black 7, CI Solvent Black 123, CI Solvent Blue 2, CI Solvent Blue 25, CI Solvent Blue 55, CI Solvent Blue 70, CI Solvent Red 8, CI Solvent Red 49, CI Solvent Red 100, CI Solvent Violet 8, CI Solvent Violet 21, CI Solvent Green 3, CI Solvent Yellow 21, CI Solvent Yellow 44, CI Solvent Yellow 61, and CI Solvent Orange 37. Examples of disperse dyes include CI Disperse Yellow 82, CI Disperse Yellow 3, CI Disperse Yellow 54, CI Disperse Red 191, CI Disperse Red 60, and CI Disperse Violet 57.

[0020] Examples of oily media include esters such as monobasic acid esters, dibasic acid monoesters, dibasic acid diesters, partial esters and complete esters of polyhydric alcohols, aromatic hydrocarbons such as alkylbenzenes and alkylnaphthalenes, higher alcohols, ketones, and ethers. The above oily media can be used alone or in a suitable mixture of two or more.

[0021] Examples of thermochromic materials include reversible thermochromic compositions consisting of (i) an electron-donating color-forming organic compound, (ii) an electron-accepting compound, and (iii) a reaction medium that determines the temperature at which the color-forming reaction of the above components (i) and (ii) occurs. Examples of reversible thermochromic compositions that can be used include those described in Japanese Patent Publication Nos. 51-44706, 51-44707, and 1-29398, which show a color change around a certain temperature (color change point), exhibiting a colorless state in a temperature range above the high-temperature color change point and a colored state in a temperature range below the low-temperature color change point, with only one specific state existing at room temperature, and the other state being maintained while the heat or cold required to produce that state is applied, but returning to the state exhibited at room temperature once the application of heat or cold is removed. These compositions have a relatively small hysteresis width (ΔH) (ΔH = 1 to 7°C) and are heat-discolorable (discolored by heating and colored by cooling) (see Figure 1).

[0022] Furthermore, reversible thermochromic compositions may also be used that exhibit a large hysteresis width (ΔH=8-70°C), as described in JP-B No. 4-17154, JP-A No. 7-179777, JP-A No. 7-33997, JP-A No. 8-39936, JP-A No. 2005-1369, etc., and that exhibit a color change along a curve plotting the change in color density with temperature, which follows significantly different paths when the temperature is increased from a temperature lower than the color change temperature range than when the temperature is decreased from a temperature higher than the color change temperature range, and that exhibit a colored state at temperatures below the complete color change temperature t1 or a discolored state at a temperature higher than the complete discoloration temperature t4, and that have color memory in a specific temperature range (the temperature range between the color change onset temperature t2 and the discoloration onset temperature t3 (a temperature range in which two phases are essentially maintained)) (see Figure 2).

[0023] Components (a), (b), and (c) will be specifically explained below. Component (A), that is, the electron-donating color-forming organic compound, is the component that determines the color, and is a compound that donates electrons to component (B), which is the color developer, to develop color. Examples of the electron-donating color-forming organic compound include phthalide compounds, fluoran compounds, styrinoquinoline compounds, diazarhodamine lactone compounds, pyridine compounds, quinazoline compounds, and bisquinazoline compounds, and among these, phthalide compounds and fluoran compounds are preferred. Examples of the phthalide compound include a diphenylmethane phthalide compound, a phenylindolyl phthalide compound, an indolyl phthalide compound, a diphenylmethane azaphthalide compound, a phenylindolyl azaphthalide compound, and derivatives thereof. Among these, a phenylindolyl azaphthalide compound and a derivative thereof are preferred. Examples of the fluoran compound include aminofluoran compounds, alkoxyfluoran compounds, and derivatives thereof.

[0024] Examples of the electron-donating color-forming organic compound include: 3,3-bis(4-dimethylaminophenyl)-6-dimethylaminophthalide, 3-(4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)phthalide, 3,3-bis(1-n-butyl-2-methylindol-3-yl)phthalide, 3,3-bis(2-ethoxy-4-diethylaminophenyl)-4-azaphthalide, 3-(2-ethoxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(2-n-hexyloxy-4-diethylaminophenyl)-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-[2-ethoxy-4-(N-ethylanilino)phenyl]-3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide, 3-(2-acetamido-4-diethylaminophenyl)-3-(1-propyl-2-methylindol-3-yl)-4-azaphthalide, 3,6-bis(diphenylamino)fluoran, 3,6-bis(N-phenyl-Np-tolylamino)fluoran, 3,6-dimethoxyfluoran, 3,6-di-n-butoxyfluorane, 2-methyl-6-(N-ethyl-Np-tolylamino)fluoran, 3-chloro-6-cyclohexylaminofluoran, 2-methyl-6-cyclohexylaminofluoran, 2-chloroamino-6-di-n-butylaminofluoran, 2-(2-chloroanilino)-6-di-n-butylaminofluoran, 2-(3-trifluoromethylanilino)-6-diethylaminofluoran, 2-(3-trifluoromethylanilino)-6-di-n-pentylaminofluoran, 2-dibenzylamino-6-diethylaminofluoran, 2-(N-methylanilino)-6-(N-ethyl-Np-tolylamino)fluoran, 1,3-dimethyl-6-diethylaminofluoran, 2-chloro-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methoxy-6-diethylaminofluoran, 2-anilino-3-methyl-6-di-n-butylaminofluoran, 2-anilino-3-methoxy-6-di-n-butylaminofluoran, 2-xylidino-3-methyl-6-diethylaminofluoran, 2-anilino-3-methyl-6-(N-ethyl-Np-tolylamino)fluoran, 6-diethylamino-1,2-benzofluoran, 6-(N-ethyl-N-isobutylamino)-1,2-benzofluoran, 6-(N-ethyl-N-isoamylamino)-1,2-benzofluoran, 2-(3-methoxy-4-dodecoxystyryl)quinoline, 2-diethylamino-8-diethylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-di-n-butylamino-8-di-n-butylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-di-n-butylamino-8-diethylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-di-n-butylamino-8-(N-ethyl-N-isoamylamino)-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 2-di-n-butylamino-8-di-n-pentylamino-4-methylspiro[5H-[1]benzopyrano[2,3-d]pyrimidin-5,1′(3′H)-isobenzofuran]-3′-one, 4,5,6,7-tetrachloro-3-(4-dimethylamino-2-methoxyphenyl)-3-(1-n-butyl-2-methylindol-3-yl)-1(3H)-isobenzofuranone, 4,5,6,7-tetrachloro-3-(4-diethylamino-2-ethoxyphenyl)-3-(1-ethyl-2-methylindol-3-yl)-1(3H)-isobenzofuranone, 4,5,6,7-tetrachloro-3-(4-diethylamino-2-ethoxyphenyl)-3-(1-n-pentyl-2-methylindol-3-yl)-1(3H)-isobenzofuranone, 4,5,6,7-tetrachloro-3-(4-diethylamino-2-methylphenyl)-3-(1-ethyl-2-methylindol-3-yl)-1(3H)-isobenzofuranone, 3',6'-bis[phenyl(2-methylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, 3',6'-bis[phenyl(3-methylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, 3',6'-bis[phenyl(3-ethylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthen]-3-one, 2,6-bis(2′-ethyloxyphenyl)-4-(4′-dimethylaminophenyl)pyridine, 2,6-bis(2′,4′-diethyloxyphenyl)-4-(4′-dimethylaminophenyl)pyridine, 2-(4′-dimethylaminophenyl)-4-methoxyquinazoline, 4,4'-Ethylenedioxy-bis[2-(4-diethylaminophenyl)quinazoline] Examples include: In addition, the fluorans may be compounds having a substituent on the phenyl group forming the xanthene ring, or may be compounds that have a substituent on the phenyl group forming the xanthene ring and also have a substituent (for example, an alkyl group such as a methyl group, or a halogen atom such as a chlorine atom) on the phenyl group forming the lactone ring, and that exhibit a blue or black color.

[0025] Component (b), ie, the electron accepting compound, is a compound that accepts electrons from component (a) and functions as a developer for component (a). Examples of the electron-accepting compound include compounds selected from the group of compounds having an active proton, the group of pseudo-acidic compounds (compounds that are not acids but act as acids in the reversible thermochromic composition to cause component (A) to develop color), and the group of compounds having an electron vacancy. Among the above-mentioned component (B), compounds selected from the group of compounds having an active proton are preferred.

[0026] Examples of compounds having an active proton include compounds having a phenolic hydroxyl group and derivatives thereof, carboxylic acids and derivatives thereof, acidic phosphate esters and derivatives thereof, azole compounds and derivatives thereof, 1,2,3-triazole and derivatives thereof, cyclic carbosulfimides, halohydrins having 2 to 5 carbon atoms, sulfonic acids and derivatives thereof, and inorganic acids. Preferred examples of the carboxylic acids and derivatives thereof include aromatic carboxylic acids and derivatives thereof, and aliphatic carboxylic acids having 2 to 5 carbon atoms and derivatives thereof. Examples of the pseudo-acidic compounds include metal salts of compounds having a phenolic hydroxyl group, metal salts of carboxylic acids, metal salts of acidic phosphate esters, metal salts of sulfonic acids, aromatic carboxylic acid anhydrides, aliphatic carboxylic acid anhydrides, mixed anhydrides of aromatic carboxylic acids and sulfonic acids, cycloolefin dicarboxylic acid anhydrides, urea and its derivatives, thiourea and its derivatives, guanidine and its derivatives, and halogenated alcohols. Compounds having electron vacancies include borates, borate esters, and inorganic salts.

[0027] Among the above-mentioned components (ii), compounds having a phenolic hydroxyl group are preferred because they can more effectively exhibit thermochromic properties. Compounds having a phenolic hydroxyl group include a wide range of compounds, from monophenol compounds to polyphenol compounds, and further include bisphenol compounds, trisphenol compounds, phenol-aldehyde condensation resins, etc. The compound having a phenolic hydroxyl group preferably has at least two benzene rings. In addition, the compound having a phenolic hydroxyl group may have a substituent such as an alkyl group, an aryl group, an acyl group, an alkoxycarbonyl group, a carboxyl group and its ester or amide group, or a halogen atom.

[0028] Examples of metals contained in metal salts of compounds having a phenolic hydroxyl group include sodium, potassium, calcium, zinc, zirconium, aluminum, magnesium, nickel, cobalt, tin, copper, iron, vanadium, titanium, lead, and molybdenum.

[0029] Examples of compounds of component (b) are given below. Examples of compounds having one phenolic hydroxyl group include: phenol, o-cresol, m-cresol, p-cresol, 4-ethylphenol, 4-n-propylphenol, 4-n-butylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 4-tert-butylphenol, 4-n-pentylphenol, 4-tert-pentylphenol, 4-n-octylphenol, 4-tert-octylphenol, 4-n-nonylphenol, 4-n-dodecylphenol, 3-n-pentadecylphenol, 4-n-stearylphenol, 1-(4-hydroxyphenyl)decan-1-one, 4-chlorophenol, 4-bromophenol, 4-trifluoromethylphenol, 4-methylthiophenol, 4-nitrophenol, 2-phenylphenol, 4-phenylphenol, 2-benzylphenol, 2-benzyl-4-chlorophenol, 4-cumylphenol, 4-hydroxybenzophenone, 4-chloro-4′-hydroxybenzophenone, 4-fluoro-4′-hydroxybenzophenone, 4-cyclohexylphenol, 2-hydroxybenzyl alcohol, 3-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol, 4-(2-hydroxyethyl)phenol, 3-methoxyphenol, 4-ethoxyphenol, 4-n-propoxyphenol, 4-n-butoxyphenol, 4-n-heptyloxyphenol, 4-(2-methoxyethyl)phenol, α-naphthol, β-naphthol, 2,3-dimethylphenol, 2,4-dimethylphenol, 2,6-dimethylphenol, 2,6-di-tert-butylphenol, 2,4-dichlorophenol, 2,4-difluorophenol, thymol, 3-methyl-4-methylthiophenol, 2-tert-butyl-5-methylphenol, 2,6-bis(hydroxymethyl)-4-methylphenol, 2,3,5-trimethylphenol, 2,6-bis(hydroxymethyl)-4-tert-octylphenol, 6-hydroxy-1,3-benzoxathiol-2-one, 2,4-bis(phenylsulfonyl)phenol, 2,4-bis(phenylsulfonyl)-5-methylphenol, 2,4-bis(4-methylphenylsulfonyl)phenol, 2-phenylphenol, 4-phenylphenol, 2,6-diphenylphenol, 3-benzylbiphenyl-2-ol, 3,5-dibenzylbiphenyl-4-ol, 4-cyano-4′-hydroxybiphenyl, 1-hydroxybenzotriazole, 1-hydroxy-5-methylbenzotriazole, 1-hydroxy-5-chlorobenzotriazole, 1-hydroxy-5-methoxybenzotriazole, 1-hydroxy-4-benzoylaminobenzotriazole, 1-hydroxy-4,5,6,7-tetrachlorobenzotriazole, 1,4-hydroxybenzotriazole, 1-hydroxy-5-nitrobenzotriazole, 1-hydroxy-5-phenylbenzotriazole, 1-hydroxy-5-benzylbenzotriazole, 1-hydroxy-5-ethylbenzotriazole, 1-hydroxy-5-n-octylbenzotriazole, 1-hydroxy-5-n-butylbenzotriazole, n-Butyl 4-hydroxybenzoate, n-Octyl 4-hydroxybenzoate, 4-Hydroxybenzoic acid 2-heptadecafluorooctylethane, benzyl 4-hydroxybenzoate, 4-hydroxybenzoic acid benzyl ester, o-methylbenzyl 4-hydroxybenzoate, m-methylbenzyl 4-hydroxybenzoate, p-methylbenzyl 4-hydroxybenzoate, p-ethylbenzyl 4-hydroxybenzoate, p-propylbenzyl 4-hydroxybenzoate, p-tert-butylbenzyl 4-hydroxybenzoate, phenylethyl 4-hydroxybenzoate, 4-hydroxybenzoic acid-o-methylphenylethyl ester, m-Methylphenylethyl 4-hydroxybenzoate, p-methylphenylethyl 4-hydroxybenzoate, p-Ethylphenylethyl 4-hydroxybenzoate, p-propylphenylethyl 4-hydroxybenzoate, p-tert-butylphenylethyl 4-hydroxybenzoate Examples include:

[0030] Examples of compounds having two phenolic hydroxyl groups include: Resorcinol, 2-methylresorcinol, 4-n-hexylresorcinol, 4-n-octylresorcinol, 4-tert-octylresorcinol, 4-benzoylresorcinol, 4-nitroresorcinol, β-methyl resorcylate, β-benzyl resorcylate, 2-chloro-4-pentanoylresorcinol, 6-chloro-4-pentanoylresorcinol, 2-chloro-4-hexanoylresorcinol, 6-chloro-4-hexanoylresorcinol, 2-chloro-4-propanoylresorcinol, 6-chloro-4-propanoylresorcinol, 2,6-dichloro-4-propanoylresorcinol, 6-fluoro-4-propanoylresorcinol, 2-chloro-4-phenylacetylresorcinol, 6-chloro-4-phenylacetylresorcinol, 2-chloro-4-β-phenylpropanoylresorcinol, 6-chloro-4-β-phenylpropanoylresorcinol, 2-chloro-4-phenoxyacetylresorcinol, 6-chloro-4-phenoxyacetylresorcinol, 4-benzoyl-2-chlororesorcinol, 6-chloro-4-m-methylbenzoylresorcinol, 4-[1',3',4',9'a-tetrahydro-6'-hydroxyspiro(cyclohexane-1,9'-[9H]-xanthene)-4'a-[2H]-yl]-1,3-benzenediol, hydroquinone, methylhydroquinone, trimethylhydroquinone, Catechol, 4-tert-butylcatechol, 1,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,5-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 2,4-dihydroxybenzophenone, 4,4′-dihydroxybenzophenone, 2,4-dihydroxy-2′-methylbenzophenone, 2,4-dihydroxy-3′-methylbenzophenone, 2,4-dihydroxy-4′-methylbenzophenone, 2,4-dihydroxy-4′-ethylbenzophenone, 2,4-dihydroxy-4′-n-propylbenzophenone, 2,4-dihydroxy-4′-isopropylbenzophenone, 2,4-dihydroxy-4′-n-butylbenzophenone, 2,4-dihydroxy-4′-isobutylbenzophenone, 2,4-dihydroxy-4′-tert-butylbenzophenone, 2,4-dihydroxy-4′-n-pentylbenzophenone, 2,4-dihydroxy-4′-n-hexylbenzophenone, 2,4-dihydroxy-4′-n-heptylbenzophenone, 2,4-dihydroxy-4′-n-octylbenzophenone, 2,4-dihydroxy-4′-n-decylbenzophenone, 2,4-dihydroxy-2′,3′-dimethylbenzophenone, 2,4-dihydroxy-2′,4′-dimethylbenzophenone, 2,4-dihydroxy-2′,5′-dimethylbenzophenone, 2,4-dihydroxy-2′,6′-dimethylbenzophenone, 2,4-dihydroxy-3′,4′-dimethylbenzophenone, 2,4-dihydroxy-3′,5′-dimethylbenzophenone, 2,4-dihydroxy-2′,4′,6′-trimethylbenzophenone, 2,4-dihydroxy-2′-methoxybenzophenone, 2,4-dihydroxy-3′-methoxybenzophenone, 2,4-dihydroxy-4′-methoxybenzophenone, 2,4-dihydroxy-2′-ethoxybenzophenone, 2,4-dihydroxy-4′-ethoxybenzophenone, 2,4-dihydroxy-4′-n-propoxybenzophenone, 2,4-dihydroxy-4′-isopropoxybenzophenone, 2,4-dihydroxy-4′-n-butoxybenzophenone, 2,4-dihydroxy-4′-isobutoxybenzophenone, 2,4-dihydroxy-4′-n-pentyloxybenzophenone, 2,4-dihydroxy-4′-n-hexyloxybenzophenone, 2,4-dihydroxy-4′-n-heptyloxybenzophenone, 2,4-dihydroxy-4′-n-octyloxybenzophenone, 2,4-dihydroxy-4′-n-nonyloxybenzophenone, 2,4-dihydroxy-2′,3′-dimethoxybenzophenone, 2,4-dihydroxy-2′,4′-dimethoxybenzophenone, 2,4-dihydroxy-2′,5′-dimethoxybenzophenone, 2,4-dihydroxy-2′,6′-dimethoxybenzophenone, 2,4-dihydroxy-3′,4′-dimethoxybenzophenone, 2,4-dihydroxy-3′,5′-dimethoxybenzophenone, 2,4-dihydroxy-3′,4′-diethoxybenzophenone, 2,4-dihydroxy-2′,3′,4′-trimethoxybenzophenone, 2,4-dihydroxy-2′,3′,6′-trimethoxybenzophenone, 2,4-dihydroxy-3′,4′,5′-trimethoxybenzophenone, 2,4-Dihydroxy-3',4',5'-triethoxybenzophenone Examples include:

[0031] Further, examples of bisphenol compounds include: 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl) n-butane, 1,1-bis(4-hydroxyphenyl) n-pentane, 1,1-bis(4-hydroxyphenyl) n-hexane, 1,1-bis(4-hydroxyphenyl) n-heptane, 1,1-bis(4-hydroxyphenyl) n-octane, 1,1-bis(4-hydroxyphenyl)n-nonane, 1,1-bis(4-hydroxyphenyl) n-decane, 1,1-bis(4-hydroxy-3-methylphenyl)decane, 1,1-bis(4-hydroxyphenyl) n-dodecane, 1,1-bis(4-hydroxyphenyl)-2-methylpropane, 1,1-bis(4-hydroxyphenyl)-3-methylbutane, 1,1-bis(4-hydroxyphenyl)-3-methylpentane, 1,1-bis(4-hydroxyphenyl)-2,3-dimethylpentane, 1,1-bis(4-hydroxyphenyl)-2-ethylbutane, 1,1-bis(4-hydroxyphenyl)-2-ethylhexane, 1,1-bis(4-hydroxyphenyl)-3,7-dimethyloctane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane, 1,1-bis(4-hydroxy-3-methyl)cyclohexane, diphenolic acid, 1-phenyl-1,1-bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxyphenyl) n-butane, 2,2-bis(4-hydroxyphenyl) n-pentane, 2,2-bis(4-hydroxyphenyl) n-hexane, 2,2-bis(4-hydroxyphenyl) n-heptane, 2,2-bis(4-hydroxyphenyl) n-octane, 2,2-bis(4-hydroxyphenyl)n-nonane, 2,2-bis(4-hydroxyphenyl) n-decane, 2,2-bis(4-hydroxyphenyl) n-dodecane, 2,2-bis(4-hydroxyphenyl)-6,10,14-trimethylpentadecane, 1-phenyl-1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)methylpropionate, 2,2-bis(4-hydroxyphenyl)butylpropionate, 2,2-bis(4-hydroxy-3-methylphenyl)methylpropionate, 2,2-bis(4-hydroxyphenyl)ethyl propionate, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 2,2-bis(4-hydroxyphenyl)-4-methylhexane, 2,2-bis(4-hydroxyphenyl)hexafluoropropane, 2,2-bis(3,5-dihydroxymethyl-4-hydroxyphenyl)hexafluoropropane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)butane, 2,2-bis(4-hydroxy-3-isopropylphenyl)propane, 2,2-bis(3-sec-butylphenyl-4-hydroxy)propane, 2,2-bis(4-hydroxy-3-phenylphenyl)propane, 2,2-bis(3-tert-butyl-4-hydroxyphenyl)propane, 2,2-bis(3-fluoro-4-hydroxyphenyl)propane, 2,2-bis(3,5-dihydroxymethyl-4-hydroxyphenyl)propane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 1,3-bis[2-(4-hydroxyphenyl)-2-propyl]benzene, 1,4-bis[2-(4-hydroxyphenyl)-2-propyl]benzene, 3,3-bis(4-hydroxyphenyl)oxindole, 3,3-bis(4-hydroxy-3-methylphenyl)oxindole, bis(2-hydroxyphenyl)methane, bis(2-hydroxy-5-methylphenyl)methane, bis(2-hydroxy-3-hydroxymethyl-5-methyl)methane, 4,4'-[1,4-phenylenebis(1-methylethylidene)]bis(2-methylphenol), 1,1-bis(4-hydroxy-3-phenylphenyl)cyclohexane, 3,3-ethyleneoxydiphenol, 1,4-bis(4-hydroxybenzoate)-3-methylbenzene, 4,4"-dihydroxy-3"-methyl-p-terphenyl, 4,4″-dihydroxy-3″-isopropyl-p-terphenyl, 2,2-dimethyl-1,3-bis(4-hydroxybenzoyloxy)propane, 2,2′-biphenol, 4,4′″-dihydroxy-p-quaterphenyl, 4,4-dihydroxydiphenyl ether, Bis(4-hydroxyphenylthioethyl) ether bis(4-hydroxyphenyl) sulfone, 4-benzyloxy-4′-hydroxydiphenyl sulfone, 4-(4-methylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(4-ethylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(4-n-propylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(4-isopropylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(4-n-butylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(4-isobutylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(4-sec-butylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(4-tert-butylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(3-methylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(3-ethylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(3-n-propylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(3-isopropylbenzyloxy)-4′-dihydroxyphenyl sulfone, 4-(3-n-butylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(3-isobutylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(3-sec-butylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(3-tert-butylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(2-methylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(2-ethylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(2-n-propylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(2-isopropylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(2-n-butylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(2-isobutylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(2-sec-butylbenzyloxy)-4′-hydroxydiphenyl sulfone, 4-(2-tert-butylbenzyloxy)-4′-hydroxydiphenyl sulfone, 2,4′-dihydroxydiphenyl sulfone, 3,4′-dihydroxydiphenyl sulfone, 4-hydroxydiphenyl sulfone, 4-methyl-4'-hydroxyphenyl sulfone, 4-ethyl-4′-hydroxydiphenyl sulfone, 4-n-propyl-4′-hydroxydiphenyl sulfone, 4-isopropyl-4′-hydroxydiphenyl sulfone, 4-chloro-4′-hydroxydiphenyl sulfone, 4-fluoro-4′-hydroxydiphenyl sulfone, 4-chloro-2-methyl-4′-hydroxydiphenyl sulfone, 4-methoxy-4′-hydroxydiphenyl sulfone, 4-ethoxy-4′-hydroxydiphenyl sulfone, 4-n-propoxy-4′-hydroxydiphenyl sulfone, 4-isopropoxy-4′-hydroxydiphenyl sulfone, 4-n-butoxy-4′-hydroxydiphenyl sulfone, 4-isobutoxy-4′-hydroxydiphenyl sulfone, 4-sec-butoxy-4′-hydroxydiphenyl sulfone, 4-tert-butoxy-4′-hydroxydiphenyl sulfone, 4-n-pentyloxy-4′-hydroxydiphenyl sulfone, 4-isopentyloxy-4′-hydroxydiphenyl sulfone, 4-(1-propenyloxy)-4′-hydroxydiphenyl sulfone, 4-(2-propenyloxy)-4′-hydroxydiphenyl sulfone, 4-benzyloxy-4′-hydroxydiphenyl sulfone, 4-(β-phenoxyethoxy)-4′-hydroxydiphenyl sulfone, 4-(β-phenoxypropoxyl)-4′-hydroxydiphenyl sulfone, bis(2-allyl-4-hydroxydiphenyl) sulfone, bis[4-hydroxy-3-(2-propenyl)phenyl]sulfone, bis(3,5-dibromo-4-hydroxyphenyl) sulfone, bis(3,5-dichloro-4-hydroxyphenyl) sulfone, bis(3-phenyl-4-hydroxyphenyl) sulfone, bis(4-hydroxy-3-n-propylphenyl) sulfone, bis(4-hydroxy-3-methylphenyl) sulfone, 3,4-dihydroxydiphenyl sulfone, 3',4'-dihydroxy-4-methyldiphenyl sulfone, 3,4,4′-trihydroxydiphenyl sulfone, bis(3,4-dihydroxyphenyl) sulfone, 2,3,4-trihydroxydiphenyl sulfone, 4-isopropoxy-4′-hydroxydiphenyl sulfone, 4-n-propoxy-4′-hydroxydiphenyl sulfone, 4-allyloxy-4′-hydroxydiphenyl sulfone, 4-benzyloxy-4′-hydroxydiphenyl sulfone, 4-(2-propenyloxy)-4′-hydroxydiphenyl sulfone, 3-benzyl-4-benzyloxy-4′-hydroxydiphenyl sulfone, 3-phenethyl-4-phenethyloxy-4′-hydroxydiphenyl sulfone, 3-methylbenzyl-4-methylbenzyloxy-4′-hydroxydiphenyl sulfone, 4-benzyloxy-3′-benzyl-4′-hydroxydiphenyl sulfone, 4-phenethyloxy-3′-phenethyl-4′-hydroxydiphenyl sulfone, 4-methylbenzyloxy-3′-methylbenzyl-4′-hydroxydiphenyl sulfone, α,α′-bis{4-(p-hydroxyphenylsulfone)phenoxy}-p-xylene, 4,4′-{oxybis(ethylene oxide-p-phenylene sulfonyl)}diphenol, Bis(4-hydroxyphenyl) sulfide, bis(4-hydroxy-3-methylphenyl) sulfide, bis(3,5-dimethyl-4-hydroxyphenyl) sulfide, bis(3-ethyl-4-hydroxyphenyl) sulfide, bis(3,5-diethyl-4-hydroxyphenyl) sulfide, bis(4-hydroxy-3-n-propylphenyl) sulfide, bis(3,5-di-n-propyl-4-hydroxyphenyl) sulfide, bis(3-tert-butyl-4-hydroxyphenyl) sulfide, bis(3,5-di-tert-butyl-4-hydroxyphenyl) sulfide, bis(4-hydroxy-3-n-pentylphenyl) sulfide, bis(3-n-hexyl-4-hydroxyphenyl) sulfide, bis(3-n-heptyl-4-hydroxyphenyl) sulfide, bis(5-tert-octyl-2-hydroxyphenyl) sulfide, bis(2-hydroxy-3-tert-octylphenyl) sulfide, bis(2-hydroxy-5-n-octylphenyl) sulfide, bis(5-chloro-2-hydroxyphenyl) sulfide, bis(3-cyclohexyl-4-hydroxyphenyl) sulfide, bis(4-hydroxyphenylthioethoxy)methane, 1,5-(4-hydroxyphenylthio)-3-oxypentane, 1,8-bis(4-hydroxyphenylthio)-3,6-dioxaoctane Examples include:

[0032] Examples of compounds having three phenolic hydroxyl groups include pyrogallol, phloroglucinol, phloroglucinolcarboxylic acid, gallic acid, octyl gallate, and dodecyl gallate.

[0033] Further examples of trisphenol compounds include: 4,4′,4″-methylidynetrisphenol, 4,4′,4″-methylidynetris(2-methylphenol), 4,4'-[(2-hydroxyphenyl)methylene]bis(2,3,5-trimethylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2-methylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(4-hydroxy-3-methoxyphenyl)methylene]bisphenol, 4,4'-[(4-hydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol), 4,4′,4″-ethylidynetrisphenol, 4,4′,4″-ethylidinetris(2-methylphenol), 4,4'-[(2-hydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol), 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-methylphenol, 2,4-bis[(2-hydroxy-5-methylphenyl)methyl]-6-cyclohexylphenol, 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}methylidene]bisphenol, 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bisphenol, 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}propylidene]bisphenol, 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}butylidene]bisphenol, 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}pentylidene]bisphenol, 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}hexylidene]bisphenol, 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}heptylidene]bisphenol, 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}isobutylidene]bisphenol, 4,4'-[1-{4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl}neopentylidene]bisphenol, 2,2'-[1-{4-[1-(2-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bisphenol, 3,3′-[1-{4-[1-(3-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bisphenol, 4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-fluorophenol), 4,4'-[1-{4-[1-(3-chloro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-chlorophenol), 4,4'-[1-{4-[1-(3-bromo-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-bromophenol), 4,4'-[1-{4-[1-(4-hydroxy-3-methylphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-methylphenol), 4,4'-[1-{4-[1-(3-ethyl-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-ethylphenol), 4,4'-[1-{4-[1-(3-tert-butyl-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-tert-butylphenol), 4,4'-[1-{4-[1-(4-hydroxy-3-trifluoromethylphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-trifluoromethylphenol), 1,1-bis(4-hydroxyphenyl)-4-(4-hydroxy-α-ethyl)benzylcyclohexane, 4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bisphenol, 4,4'-[(3-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), 2,2'-[(4-hydroxyphenyl)methylene]bis(3,5-dimethylphenol), 4,4'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(2,6-dimethylphenol), 2,2'-[(2-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol), 4,4'-[(3-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 4,4'-[(3-hydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol), 4,4'-[(4-hydroxyphenyl-3-methoxy)methylene]bis(2-cyclohexyl-5-methylphenol), 1,1-bis(4-hydroxyphenyl)-4-hydroxyphenylcyclohexane, 4,4'-[3-(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-phenyl)propylidene]bis(2-cyclohexyl-5-methylphenol), 4,4'-[(2-hydroxyphenyl)methylene]bis(2-methylphenol), 2,4′,4″-methylidynetrisphenol, 4,4'-[(2-hydroxyphenyl)methylene]bis(3-methylphenol), 4,4'-[4-(4-hydroxyphenyl)-sec-butylidene]bis(4-hydroxyphenol), 2,2'-[(3-hydroxyphenyl)methylene]bis(3,5-dimethylphenol), 4,4'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(2,5-dimethylphenol), 4,4'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(2,6-dimethylphenol), 2,2'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(3,5-dimethylphenol), 2,2'-[(3-hydroxy-4-methoxyphenyl)methylene]bis(3,5-dimethylphenol), 2,2'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(3,5-dimethylphenol), 4,4'-[(2-hydroxyphenyl)methylene]bis(2-isopropylphenol), 4,4'-[(3-hydroxyphenyl)methylene]bis(2-isopropylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2-isopropylphenol), 2,2'-[(3-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol), 2,2'-[(4-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol), 2,2'-[(4-3-ethoxy-4-hydroxyphenyl)methylene]bis(3,5-dimethylphenol), 1,1-bis(4-hydroxy-3-methylphenyl)-4-(4-hydroxyphenyl)cyclohexane, 4,4'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(2-isopropylphenol), 4,4'-[(3-hydroxy-4-methoxyphenyl)methylene]bis(2-isopropylphenol), 4,4'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(2-isopropylphenol), 2,2'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(3,5,6-trimethylphenol), 2,2'-[(3-hydroxy-4-methoxyphenyl)methylene]bis(3,5,6-trimethylphenol), 2,2'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(3,5,6-trimethylphenol), 4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(2-isopropylphenol), 2,2'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol), 4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)-4-(4-hydroxyphenyl)cyclohexane, 4,4'-[(4-hydroxy-3-methoxyphenyl)methylene]bis(2-tert-butyl-5-methylphenol), 4,4'-[(2-hydroxyphenyl)methylene]bis(2-cyclohexylphenol), 4,4'-[(3-hydroxyphenyl)methylene]bis(2-cyclohexylphenol), 4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(2-tert-butyl-6-methylphenol), 4,4'-[(3-methoxy-2-hydroxyphenyl)methylene]bis(2-cyclohexylphenol), 4,4'-[(3-hydroxy-4-methoxyphenyl)methylene]bis(2-cyclohexylphenol), 4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-tert-butylphenol), 4,4'-[1-{4-[1-(3,5-dimethyl-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2,6-dimethylphenol), 4,4'-[(3-ethoxy-4-hydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol), 4,4'-[(3-cyclohexyl-4-hydroxyphenyl)ethylidene]bis(2-cyclohexylphenol), 4,4'-[(5-cyclohexyl-4-hydroxy-2-methoxyphenyl)ethylidene]bis(2-cyclohexyl-5-methylphenol), 4,4'-[1-{4-[1-(3-cyclohexyl-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-cyclohexylphenol), 4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bisphenol, 4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2-methylphenol), 4,4'-[1-{4-[1-(3-fluoro-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis(2,6-dimethylphenol), 2,6-bis[(5-fluoro-2-hydroxyphenyl)methyl]-4-methylphenol, 2,6-bis[(3,5-dimethyl-4-hydroxyphenyl)methyl]-4-methylphenol, 2,6-bis[(4-hydroxyphenyl)methyl]-4-methylphenol, 2,6-bis[(4-hydroxyphenyl)methyl]-4-ethylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-methylphenol, 2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-methylphenol, 2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-ethylphenol, 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-ethylphenol, 2,6-bis[(3,5-dimethyl-2-hydroxyphenyl)methyl]-4-methylphenol, 2,6-bis[(2,4-dimethyl-6-hydroxyphenyl)methyl]-4-methylphenol, 2,4-bis[(4-hydroxyphenyl)methyl]-6-cyclohexylphenol, 2,6-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-3,4-dimethylphenol, 2,6-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-4-ethylphenol, 2,6-bis[(4-hydroxy-2,3,6-trimethylphenyl)methyl]-4-methylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-cyclohexylphenol, 2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-cyclohexylphenol, 2,6-bis[(2-hydroxy-5-methylphenyl)methyl]-4-cyclohexylphenol, 2,6-bis[(4-hydroxy-2,3,5-trimethylphenyl)methyl]-4-ethylphenol, 2,4-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-6-cyclohexylphenol, 4,4′,4″-methylidynetris(2,6-dimethylphenol), α-(4-hydroxy-3-methylphenyl)-α,α′-bis(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, α′-(4-hydroxy-3-methylphenyl)-α,α-bis(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, α,α-bis(4-hydroxy-3-methylphenyl)-α′-(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, α,α′-bis(4-hydroxy-3-methylphenyl)-α-(4-hydroxyphenyl)-1-ethyl-4-isopropylbenzene, 1,1-bis(4-hydroxyphenyl)-4-[1-(4-hydroxyphenyl)-1-methylpropyl]cyclohexane, 2,6-bis[(3,5-dimethyl-4-hydroxyphenyl)methyl]-4-ethylphenol, 1,1′-bis(4-hydroxyphenyl)-4-[1-(4-hydroxyphenyl)propyl]cyclohexane, 1,1′-bis(4-hydroxy-3-methylphenyl)-4-[1-(4-hydroxyphenyl)propyl]cyclohexane, 1,1′-bis(3,5-dimethyl-4-hydroxyphenyl)-4-[1-(4-hydroxyphenyl)propyl]cyclohexane, 1-(4-hydroxyphenyl)-1-[4,4-bis(4-hydroxyphenyl)cyclohexyl]-4-isopropylcyclohexane, 4,4'-[3-(2,5-dimethyl-4-hydroxyphenyl)butylene]bis(2,5-dimethylphenol), 1,3,5-tri(4-hydroxy-3-phenylphenyl)adamantane, 1,3,5-tri(3-cyclohexyl-4-hydroxyphenyl)adamantane, 2,4-bis[(3,5-dimethyl-4-hydroxyphenyl)methyl]-6-cyclohexylphenol, 2,6-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-4-cyclohexylphenol, 2,4-bis[(3-cyclohexyl-4-hydroxyphenyl)methyl]-6-methylphenol, 2,4-bis[(4-hydroxy-2,3,5-trimethylphenyl)methyl]-6-cyclohexylphenol, 2,6-bis[(5-fluoro-2-hydroxyphenyl)methyl]-4-fluorophenol, 2,6-bis[(3-fluoro-4-hydroxyphenyl)methyl]-4-fluorophenol, 2,4-bis[(3-fluoro-4-hydroxyphenyl)methyl]-6-methylphenol, 4,4'-[3-(5-cyclohexyl-4-hydroxy-2-methylphenyl)-3-biphenylpropylidene]bis(5-cyclohexyl-2-methylphenol), 4,4'-[3-(2,5-dimethyl-4-hydroxyphenyl)-3-phenylpropylidene]bis(2,5-dimethylphenol), 2,4-bis[(2,5-dimethyl-4-hydroxyphenyl)methyl]-6-methylphenol, 1,1,2-tris(4-hydroxyphenyl)ethane, 1,1,3-tris(4-hydroxyphenyl)propane, 1,1,4-tris(4-hydroxyphenyl)butane, 1,2,2-tris(4-hydroxyphenyl)propane, 1,2,2-tris(4-hydroxyphenyl)butane, 1,2,2-tris(4-hydroxyphenyl)pentane, 1,2,2-tris(4-hydroxyphenyl)hexane, 1,2,2-tris(4-hydroxyphenyl)heptane, 1,2,2-tris(4-hydroxyphenyl)octane, 1,2,2-tris(4-hydroxyphenyl)-3-methylbutane, 1,2,2-tris(4-hydroxyphenyl)-3,3-dimethylbutane, 1,2,2-tris(4-hydroxyphenyl)-4,4-dimethylpentane, 1,3,3-tris(4-hydroxyphenyl)butane, 1,3,3-tris(4-hydroxyphenyl)pentane, 1,3,3-tris(4-hydroxyphenyl)hexane, 1,3,3-tris(4-hydroxyphenyl)heptane, 1,3,3-tris(4-hydroxyphenyl)octane, 1,3,3-tris(4-hydroxyphenyl)nonane, 1,4,4-tris(4-hydroxyphenyl)pentane, 1,4,4-tris(4-hydroxyphenyl)hexane, 1,4,4-tris(4-hydroxyphenyl)heptane, 1,4,4-tris(4-hydroxyphenyl)octane, 1,4,4-tris(4-hydroxyphenyl)nonane, 1,4,4-tris(4-hydroxyphenyl)decane, 1,2,2-tris(2-hydroxyphenyl)propane, 1,1,2-tris(3-hydroxyphenyl)propane, 1-(4-hydroxyphenyl)-2,2-bis(2-hydroxyphenyl)propane, 1,2,2-tris(3-fluoro-4-hydroxyphenyl)propane, 1,2,2-tris(3-chloro-4-hydroxyphenyl)propane, 1,2,2-tris(3-bromo-4-hydroxyphenyl)propane, 2,2-bis(3-ethyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)propane, 2,2-bis(3-tert-butyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)propane, 2,2-bis(2-hydroxy-3-biphenylyl)-1-(4-hydroxyphenyl)propane, 2,2-bis(3-trifluoromethyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)propane, 2-(3-methyl-4-hydroxyphenyl)-1,2-bis(4-hydroxyphenyl)propane, 1-(3-methyl-4-hydroxyphenyl)-2,2-bis(4-hydroxyphenyl)propane, 3-(3-methyl-4-hydroxyphenyl)-1,3-bis(4-hydroxyphenyl)butane, 1-(3-methyl-4-hydroxyphenyl)-3,3-bis(4-hydroxyphenyl)butane, 4-(3-methyl-4-hydroxyphenyl)-1,4-bis(4-hydroxyphenyl)pentane, 1-(3-methyl-4-hydroxyphenyl)-4,4-bis(4-hydroxyphenyl)pentane, 1,2-bis(3-methyl-4-hydroxyphenyl)-2-(4-hydroxyphenyl)propane, 3,3-bis(3-methyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)butane, 1,3-bis(3-methyl-4-hydroxyphenyl)-3-(4-hydroxyphenyl)butane, 4,4-bis(3-methyl-4-hydroxyphenyl)-1-(4-hydroxyphenyl)pentane, 1,4-bis(3-methyl-4-hydroxyphenyl)-4-(4-hydroxyphenyl)pentane, 1,1,2-tris(3-methyl-4-hydroxyphenyl)ethane, 1,2,2-tris(3-methyl-4-hydroxyphenyl)propane, 1,1,3-tris(3-methyl-4-hydroxyphenyl)propane, 1,3,3-tris(3-methyl-4-hydroxyphenyl)butane, 1,1,4-tris(3-methyl-4-hydroxyphenyl)butane, 1,4,4-tris(3-methyl-4-hydroxyphenyl)pentane, 4,4'-[4-(4-hydroxyphenyl)-sec-butylidene]bis(2-methylphenol) Examples include:

[0034] Examples of compounds having four or more phenolic hydroxyl groups include: Bis[2-hydroxy-3-(2-hydroxy-5-methylbenzyl)-5-methylphenyl]methane, 4,6-bis[(4-hydroxyphenyl)methyl]-1,3-benzenediol, 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2-cyclohexyl-5-methylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2-methylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 1,1,2,2-tetrakis(4-hydroxyphenyl)ethane, 4,4′,4″,4′″-(1,1,2,2-ethanetetrayl)tetrakis(2-methylphenol), 4,4',4'',4'''-(1,1,2,2-ethanetetrayl)tetrakis(2,6 -dimethylphenol), 4,4',4"4'"-(1,4-phenylene)bis(methylidyne)tetrakis(2,6-dimethylphenol), 2,2'-bis[4,4-bis(4-hydroxy-3-methylphenyl)cyclohexyl]propane, 2,2'-[(3,4-dihydroxyphenyl)methylene]bis(3,5-dimethylphenol), 4,6-bis[(3,5-dimethyl-4-hydroxyphenyl)methyl]-1,3-benzenediol, 2,2'-[(3,4-dihydroxyphenyl)methylene]bis(3,5,6-trimethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2-cyclohexylphenol), Bis[4-hydroxy-3-(2-hydroxybenzyl)-5-methylphenyl]methane, Bis[4-hydroxy-3-(3-hydroxybenzyl)-5-methylphenyl]methane, bis[4-hydroxy-3-(4-hydroxybenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(2-hydroxybenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(3-hydroxybenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(4-hydroxybenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(3-hydroxy-4-methylbenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(4-hydroxy-3-methylbenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(3-hydroxy-2-methylbenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(2-hydroxy-3-methylbenzyl)-5-methylphenyl]methane, α,α′,α″,α′″-tetrakis(4-hydroxyphenyl)-p-xylene, Bis[2-hydroxy-3-(4-hydroxy-2,3,5-trimethylbenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(2,5-dimethyl-3-hydroxybenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(2,5-dimethyl-4-hydroxybenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(2,5-dimethyl-5-hydroxybenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(3,5-dimethyl-4-hydroxybenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(2-hydroxy-3,4,6-trimethylbenzyl)-5-methylphenyl]methane, Bis[2-hydroxy-3-(4-hydroxy-2,3,6-trimethylbenzyl)-5-methylphenyl]methane, 4,4′,4″,4′″-tetrakis(4-hydroxyphenyl)bicyclohexyl, Bis[4-hydroxy-3-(5-cyclohexyl-4-hydroxy-2-methylbenzyl)-5-methylphenyl]methane, 4,4′,4″,4′″-tetrakis(4-hydroxy-3-methylphenyl)bicyclohexyl, 4,6-bis(3,5-dimethyl-4-hydroxyphenyl)-1,2-benzenediol, 4,4′,4″,4′″-tetrakis(3,5-dimethyl-4-hydroxyphenyl)bicyclohexyl, 1,1-bis[5-cyclohexyl-4-hydroxy-3-(2-hydroxy-5-methylbenzyl)phenyl]cyclohexane, 1,1-bis[5-cyclohexyl-4-hydroxy-3-(3,5-dimethyl-4-hydroxybenzyl)phenyl]cyclohexane, 1,1-bis[5-cyclohexyl-4-hydroxy-3-(5-cyclohexyl-4-hydroxy-2-methylbenzyl)phenyl]cyclohexane, 4,6-bis[1-(4-hydroxyphenyl)ethyl]-1,3-benzenediol, 2,2-bis[4-hydroxy-3-(4-hydroxy-3-methylbenzyl)-5-methylphenyl]propane, 2,6-bis[(3,5-dimethyl-4-hydroxyphenyl)benzyl]-4-[α-methyl-(3,5-dimethyl-4-hydroxyphenyl)benzyl]phenol, 4,4′,4″,4′″-tetrakis(3-isopropyl-4-hydroxy-phenyl)bicyclohexyl, 4,4'-bis[(3,4-dihydroxyphenyl)methylene]bis(2-isopropylphenol), 2,2'-bis[4,4-bis(4-hydroxyphenyl)cyclohexyl]propane, 2,4,6-tris(4-hydroxybenzyl)-1,3-benzenediol, 4,6-bis(3,5-dimethyl-4-hydroxybenzyl)-1,2,3-benzenetriol, 3,3'-[(2-hydroxyphenyl)methylene]bis(5-methyl-1,2-benzenediol), 2,6-bis(2,4-dihydroxybenzyl)-4-ethylphenol, 2,4-bis(2,4-dihydroxybenzyl)-6-cyclohexylphenol, 2,6-bis(5-tert-butyl-2,3-dihydroxybenzyl)-4-methylphenol, 2,4,6-tris(3,5-dimethyl-4-hydroxybenzyl)-1,2-benzenediol, 2,4,6-tris(3,5-dimethyl-2-hydroxybenzyl)-1,2-benzenediol, 2,6-bis(2,4-dihydroxybenzyl)-3,4-dimethylphenol, 2,6-bis[3-(2-hydroxy-5-methylbenzyl)-2,5-dimethyl-4-hydroxybenzyl]-3,4-dimethylphenol, 4,6-bis(α-methyl-4-hydroxybenzyl)-1,2,3-benzenetriol, 4,4'-[1-{4-[1-(3,5-bis(4-hydroxybenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxybenzyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-3-methylbenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-3-methylbenzyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(3,5-dimethyl-4-hydroxybenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3,5-dimethyl-4-hydroxybenzyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-2,3,6-trimethylbenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-2,3,6-trimethylbenzyl)phenol], Bis[5-(2,4-dihydroxybenzyl)-4-hydroxy-3-methylphenyl]methane, Bis[3-(2,4-dihydroxybenzyl)-2,5-dimethyl-4-hydroxyphenyl]methane, Bis[3-(2,4-dihydroxy-3-methylbenzyl)-2,5-dimethyl-4-hydroxyphenyl]methane, Bis[5-(4-hydroxybenzyl)-2,3,4-trihydroxyphenyl]methane, 1,1-bis[5-(4-hydroxybenzoyl)-2,3,4-trihydroxyphenyl]ethane, 3,3′,5,5′-tetrakis(4-hydroxybenzyl)-4,4′-dihydroxybiphenyl, 3,3′,5,5′-tetrakis(4-hydroxy-3-methylbenzyl)-4,4′-dihydroxybiphenyl, 3,3′,5,5′-tetrakis(2-hydroxy-5-methylbenzyl)-4,4′-dihydroxybiphenyl, 3,3′,5,5′-tetrakis(3,5-dimethyl-4-hydroxybenzyl)-4,4′-dihydroxybiphenyl, Bis[3-(α,α-bis(4-hydroxy-3-methylphenyl)methyl-4-hydroxyphenyl]methane, Bis[3,5-bis(2-hydroxy-5-methylbenzyl)-4-hydroxyphenyl]methane, 4,4',4"-ethylidinetris{[2-(2-hydroxy-5-methyl)benzyl]-6-methylphenol}, 2,2-bis[3,5-bis(2-hydroxy-5-methylphenylmethyl)phenyl]propane, Bis[3-(α,α-bis(2,5-dimethyl-4-hydroxyphenyl)methyl-4-hydroxyphenyl]methane, Bis[5-(3,5-dimethyl-4-hydroxybenzyl)-2,3,4-trihydroxyphenyl]methane, Bis[3-(2,3,4-trihydroxybenzyl)-2,5-dimethyl-4-hydroxyphenyl]methane, 1,1-bis[3-(2,3,4-trihydroxybenzyl)-5-cyclohexyl-4-hydroxyphenyl]cyclohexane, 1,8,15,22-tetranonyl-3,5,10,12,17,19,24,26-octahydroxy[1,1,1,1]-metacyclophane, 4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-2-methylbenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-2-methylbenzyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(2-hydroxy-5-methylbenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(2-hydroxy-5-methylbenzyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(3-ethyl-4-hydroxybenzyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3-ethyl-4-hydroxybenzyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(3,5-dimethyl-2-hydroxyphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3,5-dimethyl-2-hydroxyphenyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-3-isopropylphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-3-isopropylphenyl)phenol], Bis[3-(α,α-bis(3,5-dimethyl-4-hydroxyphenyl)methyl-4-hydroxyphenyl]methane, Bis[3-(α,α-bis(5-cyclohexyl-4-hydroxy-2-methylphenyl)methyl-4-hydroxyphenyl]methane, 4,4'-[4-hydroxy-3,5-bis(2-hydroxybenzyl)methylene]bis[2,6-bis(2-hydroxybenzyl)]phenol, 4,4'-[4-hydroxy-3,5-bis(4-hydroxybenzyl)methylene]bis[2,6-bis(4-hydroxybenzyl)]phenol, 4,4',4"-Ethylidinetris[2,6-bis(2-hydroxybenzyl)phenol], 4,4',4"-Ethylidinetris[2,6-bis(4-hydroxybenzyl)phenol], 2,2-bis[3,5-bis(4-hydroxy-3-methylbenzyl)-4-hydroxyphenyl]propane, 1,8,15,22-tetraethyl-3,5,10,12,17,19,24,26-octahydroxy[1,1,1,1]-metacyclophane, α,α′,α″,α′″-tetrakis(3,5-dimethyl-4-hydroxyphenyl)-1,4-dimethylbenzene, 4,4'-[1-{4-[1-(3,5-bis(2-hydroxy-5-isopropylphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(2-hydroxy-5-isopropylphenyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(4-hydroxy-2,3,5-trimethylphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(4-hydroxy-2,3,5-trimethylphenyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(3-sec-butyl-4-hydroxyphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3-sec-butyl-4-hydroxyphenyl)phenol], 4,4'-[1-{4-[1-(3,5-bis(3-tert-butyl-4-hydroxyphenyl)-4-hydroxyphenyl)-1-methylethyl]phenyl}ethylidene]bis[2,6-bis(3-tert-butyl-4-hydroxyphenyl)phenol], 2,6-bis{[3-(2,4-dihydroxybenzyl)-2,5-dimethyl-4-hydroxy]benzyl}-4-methylphenol, 1,1-bis[5-(2,4-dihydroxybenzyl)-3-cyclohexyl-4-hydroxyphenyl]cyclohexane, 1,1-bis[5-(2,3,4-trihydroxybenzyl)-3-cyclohexyl-4-hydroxyphenyl]cyclohexane, 2,2-bis[4,4',4'',4'''-tetrakis(3,5-dihydroxymethyl-4-hydroxyphenyl)cyclohexyl]propane Examples include:

[0035] Examples of carboxylic acids and derivatives thereof include: 3,5-di(α-methylbenzyl)salicylic acid, 4-(2-p-methoxyphenyloxyethoxy)salicylic acid, 4-hydroxyphenylbenzoic acid, 4-chlorobenzoic acid, 4-[2-(p-methoxyphenoxy)ethyloxy]salicylic acid, 4-[3-(p-tolylsulfonyl)propyloxy]salicylic acid, 5-[p-(2-p-methoxyphenoxyethoxy)cumyl]salicylic acid, 4-octyloxycarbonylaminosalicylic acid, 3,5-distyrenated salicylic acid, N-(p-toluenesulfonyl)-glycine, N-(p-toluenesulfonyl)-alanine, N-(p-toluenesulfonyl)-β-alanine, N-phenylaminocarbonyl-glycine, N-phenylaminocarbonyl-valine, N-(m-tolylaminocarbonyl)-phenylalanine, N-(m-tolylaminocarbonyl)-cysteine-S-benzyl, N-(m-tolylaminocarbonyl)-methionine, N-(m-tolylaminocarbonyl)-tyrosine, N-(p-tolylaminocarbonyl)-phenylalanine, N-(p-tolylaminocarbonyl)-cysteine-S-benzyl, N-(p-tolylaminocarbonyl)-methionine, N-(phenylaminocarbonyl)-methionine, N-(p-tolylaminocarbonyl)-tyrosine, 2-O-(phenylaminocarbonyl)-mandelic acid, 2-O-(p-tolylaminocarbonyl)-mandelic acid, 2-O-(m-tolylaminocarbonyl)-mandelic acid, 2-O-(o-tolylaminocarbonyl)-mandelic acid, 2-O-(1-naphthylaminocarbonyl)-mandelic acid, 2-O-(3-isopropenyl-α,α-dimethylbenzylaminocarbonyl)-mandelic acid, 2-O-(benzylaminocarbonyl)-mandelic acid, 2-O-(phenethylaminocarbonyl)-mandelic acid, 2-O-(phenylaminocarbonyl)-lactic acid, 2-O-(p-tolylaminocarbonyl)-lactic acid, 2-O-(m-tolylaminocarbonyl)-lactic acid, 2-O-(o-tolylaminocarbonyl)-lactic acid, 2-O-(1-naphthylaminocarbonyl)-lactic acid, 2-O-(3-isopropenyl-α,α-dimethylbenzylaminocarbonyl)-lactic acid, 2-O-(benzylaminocarbonyl)-lactic acid, 2-O-(phenethylaminocarbonyl)-lactic acid Examples include:

[0036] Examples of acidic phosphate ester compounds include methyl acid phosphate, ethyl acid phosphate, butyl acid phosphate, butoxyethyl acid phosphate, 2-ethylhexyl acid phosphate, isodecyl acid phosphate, isotridecyl acid phosphate, oleyl acid phosphate, tetracosyl acid phosphate, monobutyl phosphate, dibutyl phosphate, monoisodecyl phosphate, and bis(2-ethylhexyl) phosphate.

[0037] As component (b), a compound having a phenolic hydroxyl group is preferred because it can more effectively exhibit thermochromic properties, but compounds selected from aromatic carboxylic acids, aliphatic carboxylic acids having 2 to 5 carbon atoms, carboxylic acid metal salts, acidic phosphate esters and their metal salts, and 1,2,3-triazole and its derivatives may also be used.

[0038] The component (c) of the reaction medium that reversibly induces an electron transfer reaction between the components (a) and (b) in a specific temperature range will now be described. Examples of the component (c) include alcohols, esters, ketones, ethers, and acid amides. When a microcapsule pigment containing a reversible thermochromic composition is used as the colorant in the present invention, the low molecular weight component (C) evaporates out of the capsule when subjected to high heat treatment, so a compound having 10 or more carbon atoms is preferably used to stably retain it in the capsule.

[0039] As the alcohols, aliphatic monohydric saturated alcohols having 10 or more carbon atoms are effective, and examples thereof include decyl alcohol, undecyl alcohol, dodecyl alcohol, tridecyl alcohol, tetradecyl alcohol, pentadecyl alcohol, hexadecyl alcohol, heptadecyl alcohol, octadecyl alcohol, eicosyl alcohol, and docosyl alcohol.

[0040] As the esters, esters having 10 or more carbon atoms are effective, and examples thereof include esters obtained from any combination of a monocarboxylic acid having an aliphatic and alicyclic or aromatic ring and a monohydric alcohol having an aliphatic and alicyclic or aromatic ring, esters obtained from any combination of a polycarboxylic acid having an aliphatic and alicyclic or aromatic ring and a monohydric alcohol having an aliphatic and alicyclic or aromatic ring, and esters obtained from any combination of a monocarboxylic acid having an aliphatic and alicyclic or aromatic ring and a polyhydric alcohol having an aliphatic and alicyclic or aromatic ring. Examples of esters include esters obtained by combining ethyl caprylate, octyl caprylate, stearyl caprylate, myristyl caprate, docosyl caprate, 2-ethylhexyl laurate, n-decyl laurate, 3-methylbutyl myristate, cetyl myristate, isopropyl palmitate, neopentyl palmitate, nonyl palmitate, cyclohexyl palmitate, n-butyl stearate, 2-methylbutyl stearate, 3,5,5-trimethylhexyl stearate, stearyl stea ... n-Undecyl Phosphate, Pentadecyl Stearate, Stearyl Stearate, Cyclohexylmethyl Stearate, Isopropyl Behenate, Hexyl Behenate, Lauryl Behenate, Behenyl Behenate, Cetyl Benzoate, Stearyl 4-tert-Butylbenzoate, Dimyristyl Phthalate, Distearyl Phthalate, Dimyristyl Oxalate, Dicetyl Oxalate, Dicetyl Malonate, Dilauryl Succinate, Dilauryl Glutarate, Diundecyl Adipate, Dilauryl Azelaate, Di-(n-Nonyl) Sebacate, Examples include dineopentyl 1,18-octadecylmethylenedicarboxylate, ethylene glycol dimyristate, propylene glycol dilaurate, propylene glycol distearate, hexylene glycol dipalmitate, 1,5-pentanediol distearate, 1,2,6-hexanetriol trimyristate, 1,4-cyclohexanediol didecyl, 1,4-cyclohexanedimethanol dimyristate, xylene glycol dicaprinate, and xylene glycol distearate.

[0041] Also effective are esters of saturated fatty acids and branched fatty alcohols, esters of unsaturated fatty acids or branched or substituted saturated fatty acids and branched fatty alcohols or fatty alcohols having 16 or more carbon atoms, and ester compounds selected from cetyl butyrate, stearyl butyrate, and behenyl butyrate. Examples of the ester compounds include 2-ethylhexyl butyrate, 2-ethylhexyl behenate, 2-ethylhexyl myristate, 2-ethylhexyl caprate, 3,5,5-trimethylhexyl laurate, 3,5,5-trimethylhexyl palmitate, 3,5,5-trimethylhexyl stearate, 2-methylbutyl caproate, 2-methylbutyl caprylate, 2-methylbutyl caprate, 1-ethylpropyl palmitate, 1-ethylpropyl stearate, 1-ethylpropyl behenate, laurate, 1-ethylpropyl hydroxypropyl ester ... 1-Ethylhexyl phosphate, 1-ethylhexyl myristate, 1-ethylhexyl palmitate, 2-methylpentyl caproate, 2-methylpentyl caprylate, 2-methylpentyl caprate, 2-methylpentyl laurate, 2-methylbutyl stearate, 2-methylbutyl stearate, 3-methylbutyl stearate, 1-methylheptyl stearate, 2-methylbutyl behenate, 3-methylbutyl behenate, 1-methylheptyl stearate, 1-methylheptyl behenate, 1-ethyl caproate pentyl palmitate, 1-ethylpentyl palmitate, 1-methylpropyl stearate, 1-methyloctyl stearate, 1-methylhexyl stearate, 1,1-dimethylpropyl laurate, 1-methylpentyl caprate, 2-methylhexyl palmitate, 2-methylhexyl stearate, 2-methylhexyl behenate, 3,7-dimethyloctyl laurate, 3,7-dimethyloctyl myristate, 3,7-dimethyloctyl palmitate, 3,7-dimethyloctyl stearate, 3,7 behenate Examples include 3,7-dimethyloctyl erucate, stearyl oleate, behenyl oleate, stearyl linoleate, behenyl linoleate, 3,7-dimethyloctyl erucate, stearyl erucate, isostearyl erucate, cetyl isostearate, stearyl isostearate, 2-methylpentyl 12-hydroxystearate, 2-ethylhexyl 18-bromostearate, isostearyl 2-ketomyristate, 2-ethylhexyl 2-fluoromyristate, cetyl butyrate, stearyl butyrate, and behenyl butyrate.

[0042] Furthermore, in order to cause a color change that exhibits large hysteresis characteristics in the color density-temperature curve and to impart color memory properties that depend on temperature changes, exemplified are carboxylic acid ester compounds that exhibit a ΔT value (melting point-cloud point) of 5°C or more and less than 50°C, as described in Japanese Patent Publication No. 4-17154, such as carboxylic acid esters containing a substituted aromatic ring in the molecule, esters of carboxylic acids containing an unsubstituted aromatic ring and aliphatic alcohols having 10 or more carbon atoms, carboxylic acid esters containing a cyclohexyl group in the molecule, esters of fatty acids having 6 or more carbon atoms and unsubstituted aromatic alcohols or phenols, esters of fatty acids having 8 or more carbon atoms and branched aliphatic alcohols, esters of dicarboxylic acids and aromatic alcohols or branched aliphatic alcohols, dibenzyl cinnamate, heptyl stearate, didecyl adipate, dilauryl adipate, dimyristyl adipate, dicetyl adipate, distearyl adipate, trilaurin, trimyristin, tristearin, dimyristin, distearin, and the like.

[0043] Also effective are fatty acid ester compounds obtained from an odd-numbered aliphatic monohydric alcohol having 9 or more carbon atoms and an even-numbered aliphatic carboxylic acid, and fatty acid ester compounds having a total of 17 to 23 carbon atoms obtained from n-pentyl alcohol or n-heptyl alcohol and an even-numbered aliphatic carboxylic acid having 10 to 16 carbon atoms. Examples of the fatty acid ester compounds include n-pentadecyl acetate, n-tridecyl butyrate, n-pentadecyl butyrate, n-undecyl caproate, n-tridecyl caproate, n-pentadecyl caproate, n-nonyl caprylate, n-undecyl caprylate, n-tridecyl caprylate, n-pentadecyl caprylate, n-heptyl caprate, n-nonyl caprate, n-undecyl caprate, n-tridecyl caprate, n-pentadecyl caprate, n-pentyl laurate, n-heptyl laurate, n-nonyl laurate, n-undecyl laurate, n-tridecyl laurate, n-pentadecyl laurate, n-pentyl myristate, n-heptyl myristate, Examples include ethyl, n-nonyl myristate, n-undecyl myristate, n-tridecyl myristate, n-pentadecyl myristate, n-pentyl palmitate, n-heptyl palmitate, n-nonyl palmitate, n-undecyl palmitate, n-tridecyl palmitate, n-pentadecyl palmitate, n-nonyl stearate, n-undecyl stearate, n-tridecyl stearate, n-pentadecyl stearate, n-nonyl eicosanoate, n-undelci eicosanoate, n-tridecyl eicosanoate, n-pentadecyl eicosanoate, n-nonyl behenate, n-undecyl behenate, n-tridecyl behenate, and n-pentadecyl behenate.

[0044] As the ketones, aliphatic ketones having a total carbon number of 10 or more are effective, and examples thereof include 2-decanone, 3-decanone, 4-decanone, 2-undecanone, 3-undecanone, 4-undecanone, 5-undecanone, 2-dodecanone, 3-dodecanone, 4-dodecanone, 5-dodecanone, 2-tridecanone, 3-tridecanone, 2-tetradecanone, 2-pentadecanone, 8-pentadecanone, 2-hexadecanone, 3-hexadecanone, 9-heptadecanone, 2-pentadecanone, 2-octadecanone, 2-nonadecanone, 10-nonadecanone, 2-eicosanone, 11-eicosanone, 2-heneicosanone, 2-docosanone, laurone, stearone, and the like. Further, aryl alkyl ketones having a total carbon number of 12 to 24, for example, n-octadecanophenone, n-heptadecanophenone, n-hexadecanophenone, n-pentadecanophenone, n-tetradecanophenone, 4-n-dodecaacetophenone, n-tridecanophenone, 4-n-undecanoacetophenone, n-laurophenone, 4-n-decanoacetophenone, n-undecanophenone, 4-n-nonylacetophenone, n-decanophenone, 4-n-octylacetophenone, n ... Examples of acetophenone include 4-n-heptylacetophenone, n-octanophenone, 4-n-hexylacetophenone, 4-n-cyclohexylacetophenone, 4-tert-butylpropiophenone, n-heptaphenone, 4-n-pentylacetophenone, cyclohexyl phenyl ketone, benzyl-n-butyl ketone, 4-n-butylacetophenone, n-hexanophenone, 4-isobutylacetophenone, 1-acetonaphthone, 2-acetonaphthone, and cyclopentyl phenyl ketone.

[0045] As the ethers, aliphatic ethers having a total of 10 or more carbon atoms are effective, and examples thereof include dipentyl ether, dihexyl ether, diheptyl ether, dioctyl ether, dinonyl ether, didecyl ether, diundecyl ether, didodecyl ether, ditridecyl ether, ditetradecyl ether, dipentadecyl ether, dihexadecyl ether, dioctadecyl ether, decanediol dimethyl ether, undecanediol dimethyl ether, dodecanediol dimethyl ether, tridecanediol dimethyl ether, decanediol diethyl ether, and undecanediol diethyl ether.

[0046] Examples of acid amides include acetamide, propionic acid amide, butyric acid amide, caproic acid amide, caprylic acid amide, capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, oleic acid amide, erucic acid amide, benzamide, caproic acid anilide, caprylic acid anilide, capric acid anilide, lauric acid anilide, myristic acid anilide, palmitic acid anilide, stearic acid anilide, behenic acid anilide, oleic acid anilide, erucic acid anilide, and N-methyl caproate. amide, caprylic acid N-methylamide, capric acid N-methylamide, lauric acid N-methylamide, myristic acid N-methylamide, palmitic acid N-methylamide, stearic acid N-methylamide, behenic acid N-methylamide, oleic acid N-methylamide, erucic acid N-methylamide, lauric acid N-ethylamide, myristic acid N-ethylamide, palmitic acid N-ethylamide, stearic acid N-ethylamide, oleic acid N-ethylamide, lauric acid N-butylamide, myristic acid N-butylamide, palmitic acid N-butylamide, stearate Stearic acid N-butylamide, oleic acid N-butylamide, lauric acid N-octylamide, myristic acid N-octylamide, palmitic acid N-octylamide, stearic acid N-octylamide, oleic acid N-octylamide, lauric acid N-dodecylamide, myristic acid N-dodecylamide, palmitic acid N-dodecylamide, stearic acid N-dodecylamide, oleic acid N-dodecylamide, dilauric acid amide, dimyristic acid amide, dipalmitic acid amide, distearic acid amide, dioleic acid amide, trilauric acid amide, trilauric acid amide Rimyristic acid amide, tripalmitic acid amide, tristearic acid amide, trioleic acid amide, succinic acid amide, adipic acid amide, glutaric acid amide, malonic acid amide, azelaic acid amide, maleic acid amide, succinic acid N-methylamide, adipic acid N-methylamide, glutaric acid N-methylamide, malonic acid N-methylamide, azelaic acid N-methylamide, succinic acid N-ethylamide, adipic acid N-ethylamide, glutaric acid N-ethylamide, malonic acid N-ethylamide, azelaic acid N-ethylamide, succinic acid N-butylamide,Examples include adipic acid N-butylamide, glutaric acid N-butylamide, malonic acid N-butylamide, adipic acid N-octylamide, and adipic acid N-dodecylamide.

[0047] Furthermore, the component (iii) may be a compound represented by the following formula (6). [ka] [wherein R1 represents a hydrogen atom or a methyl group, m represents an integer of 0 to 2, and either X1 or X2 represents -(CH2) n OCOR2 or -(CH2) n COOR2, and the other represents a hydrogen atom; n represents an integer of 0 to 2; R2 represents an alkyl or alkenyl group having 4 or more carbon atoms; Y1 and Y2 each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom; and r and p each independently represent an integer of 1 to 3. Of the compounds represented by formula (6), when R1 is a hydrogen atom, a reversible thermochromic composition having a wider hysteresis width can be obtained, which is preferable, and it is even more preferable that R1 is a hydrogen atom and m is 0. Among the compounds represented by formula (6), the compound represented by the following formula (7) is more preferred. [ka] (In the formula, R represents an alkyl group or alkenyl group having 8 or more carbon atoms, preferably an alkyl group having 10 to 24 carbon atoms, and more preferably an alkyl group having 12 to 22 carbon atoms.) Examples of the compound represented by formula (7) include 4-benzyloxyphenylethyl octanoate, 4-benzyloxyphenylethyl nonanoate, 4-benzyloxyphenylethyl decanoate, 4-benzyloxyphenylethyl undecanoate, 4-benzyloxyphenylethyl dodecanoate, 4-benzyloxyphenylethyl tridecanoate, 4-benzyloxyphenylethyl tetradecanoate, 4-benzyloxyphenylethyl pentadecanoate, 4-benzyloxyphenylethyl hexadecanoate, 4-benzyloxyphenylethyl heptadecanoate, and 4-benzyloxyphenylethyl octadecanoate.

[0048] Furthermore, the component (iii) may be a compound represented by the following formula (8). [ka] (In the formula, R represents an alkyl or alkenyl group having 8 or more carbon atoms, m and n each independently represent an integer of 1 to 3, and X and Y each independently represent a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom.) Examples of the compound represented by formula (8) include 1,1-diphenylmethyl octanoate, 1,1-diphenylmethyl nonanoate, 1,1-diphenylmethyl decanoate, 1,1-diphenylmethyl undecanoate, 1,1-diphenylmethyl dodecanoate, 1,1-diphenylmethyl tridecanoate, 1,1-diphenylmethyl tetradecanoate, 1,1-diphenylmethyl pentadecanoate, 1,1-diphenylmethyl hexadecanoate, 1,1-diphenylmethyl heptadecanoate, and 1,1-diphenylmethyl octadecanoate.

[0049] Furthermore, the component (iii) may be a compound represented by the following formula (9). [ka] (In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, or a halogen atom; m represents an integer of 1 to 3; and n represents an integer of 1 to 20.) Examples of the compound represented by formula (9) include a diester of malonic acid and 2-[4-(4-chlorobenzyloxy)phenyl]ethanol, a diester of succinic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of succinic acid and 2-[4-(3-methylbenzyloxy)phenyl]ethanol, a diester of glutaric acid and 2-(4-benzyloxyphenyl)ethanol, a diester of glutaric acid and 2-[4-(4-chlorobenzyloxy)phenyl]ethanol, a diester of adipic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of pimelic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of suberic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of suberic acid and 2-[4-(3-methylbenzyloxy)phenyl]ethanol, a diester of glutaric acid and 2-(4-benzyloxyphenyl)ethanol, a diester of adipic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of pimelic acid and 2-(4-benzyloxyphenyl)ethanol, a diester of suberic acid and 2-[4-(3-methylbenzyloxy)phenyl]ethanol, a diester of adipic acid and 2-(4-benzyloxyphenyl) ... Examples include the diester of suberic acid and 2-[4-(4-chlorobenzyloxy)phenyl]ethanol, the diester of suberic acid and 2-[4-(2,4-dichlorobenzyloxy)phenyl]ethanol, the diester of suberic acid and 2-[4-(2,4-dichlorobenzyloxy)phenyl]ethanol, the diester of azelaic acid and 2-(4-benzyloxyphenyl)ethanol, the diester of sebacic acid and 2-(4-benzyloxyphenyl)ethanol, the diester of 1,10-decanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, the diester of 1,18-octadecanedicarboxylic acid and 2-(4-benzyloxyphenyl)ethanol, and the diester of 1,18-octadecanedicarboxylic acid and 2-[4-(2-methylbenzyloxy)phenyl]ethanol.

[0050] Furthermore, the component (iii) may be a compound represented by the following formula (10). [ka] (In the formula, R represents an alkyl group or alkenyl group having 1 to 21 carbon atoms, and n represents an integer of 1 to 3.) Examples of the compound represented by formula (10) include a diester of 1,3-bis(2-hydroxyethoxy)benzene and capric acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and undecanoic acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and lauric acid, a diester of 1,3-bis(2-hydroxyethoxy)benzene and myristic acid, a diester of 1,4-bis(hydroxymethoxy)benzene and butyric acid, a diester of 1,4-bis(hydroxymethoxy)benzene and isovaleric acid, and a diester of 1,4-bis(2-hydroxyethoxy)benzene and acetic acid. Examples of such esters include esters of 1,4-bis(2-hydroxyethoxy)benzene and propionic acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and valeric acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and caproic acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and caprylic acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and capric acid, diesters of 1,4-bis(2-hydroxyethoxy)benzene and lauric acid, and diesters of 1,4-bis(2-hydroxyethoxy)benzene and myristic acid.

[0051] Furthermore, the component (iii) may be a compound represented by the following formula (11). [ka] (In the formula, X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; m represents an integer of 1 to 3; and n represents an integer of 1 to 20.) Examples of the compound represented by formula (11) include a diester of succinic acid and 2-phenoxyethanol, a diester of suberic acid and 2-phenoxyethanol, a diester of sebacic acid and 2-phenoxyethanol, a diester of 1,10-decanedicarboxylic acid and 2-phenoxyethanol, and a diester of 1,18-octadecanedicarboxylic acid and 2-phenoxyethanol.

[0052] Furthermore, the component (iii) may be a compound represented by the following formula (12). [ka] (In the formula, R represents an alkyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, a cycloalkyl group, or an alkenyl group having 4 to 22 carbon atoms; X represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, or a halogen atom; and n represents 0 or 1.) Examples of the compound represented by formula (12) include decyl 4-phenylbenzoate, lauryl 4-phenylbenzoate, myristyl 4-phenylbenzoate, cyclohexylethyl 4-phenylbenzoate, octyl 4-biphenylacetate, nonyl 4-biphenylacetate, decyl 4-biphenylacetate, lauryl 4-biphenylacetate, myristyl 4-biphenylacetate, tridecyl 4-biphenylacetate, pentadecyl 4-biphenylacetate, cetyl 4-biphenylacetate, cyclopentyl 4-biphenylacetate, cyclohexylmethyl 4-biphenylacetate, hexyl 4-biphenylacetate, and cyclohexylmethyl 4-biphenylacetate.

[0053] Furthermore, the component (iii) may be a compound represented by the following formula (13). [ka] (In the formula, R represents an alkyl group having 3 to 18 carbon atoms or an aliphatic acyl group having 3 to 18 carbon atoms; X represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, or a halogen atom; Y represents a hydrogen atom or a methyl group; and Z represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 or 2 carbon atoms, or a halogen atom.) Examples of the compound represented by formula (13) include phenoxyethyl 4-butoxybenzoate, phenoxyethyl 4-pentyloxybenzoate, phenoxyethyl 4-tetradecyloxybenzoate, esters of phenoxyethyl 4-hydroxybenzoate and dodecanoic acid, and dodecyl ether of phenoxyethyl vanillate.

[0054] Furthermore, the component (iii) may be a compound represented by the following formula (14). [ka] (In the formula, R represents any one of an alkyl group having 4 to 22 carbon atoms, an alkenyl group having 4 to 22 carbon atoms, a cycloalkylalkyl group, and a cycloalkyl group; X represents any one of a hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom; Y represents any one of a hydrogen atom, an alkyl group, an alkoxy group, and a halogen atom; and n represents 0 or 1.) Examples of the compound represented by formula (14) include the benzoate ester of octyl 4-hydroxybenzoate, the benzoate ester of decyl 4-hydroxybenzoate, the 4-methoxybenzoate ester of heptyl 4-hydroxybenzoate, the 2-methoxybenzoate ester of dodecyl 4-hydroxybenzoate, and the benzoate ester of cyclohexylmethyl 4-hydroxybenzoate.

[0055] Furthermore, the component (iii) may be a compound represented by the following formula (15). [ka] (In the formula, R represents any one of an alkyl group having 3 to 18 carbon atoms, a cycloalkylalkyl group having 6 to 11 carbon atoms, a cycloalkyl group having 5 to 7 carbon atoms, and an alkenyl group having 3 to 18 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 3 carbon atoms, and a halogen atom; and Y represents any one of a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a methoxy group, an ethoxy group, and a halogen atom.) Examples of the compound represented by formula (15) include phenoxyethyl ether of nonyl 4-hydroxybenzoate, phenoxyethyl ether of decyl 4-hydroxybenzoate, phenoxyethyl ether of undecyl 4-hydroxybenzoate, and phenoxyethyl ether of dodecyl vanillate.

[0056] Furthermore, the component (iii) may be a compound represented by the following formula (16). [ka] (In the formula, R represents a cycloalkyl group having 3 to 8 carbon atoms or a cycloalkylalkyl group having 4 to 9 carbon atoms, and n represents an integer of 1 to 3.) Examples of the compound represented by formula (16) include a diester of 1,3-bis(2-hydroxyethoxy)benzene and cyclohexanecarboxylic acid, a diester of 1,4-bis(2-hydroxyethoxy)benzene and cyclohexanepropionic acid, and a diester of 1,3-bis(2-hydroxyethoxy)benzene and cyclohexanepropionic acid.

[0057] Furthermore, the component (iii) may be a compound represented by the following formula (17). [ka] (In the formula, R represents any one of an alkyl group having 3 to 17 carbon atoms, a cycloalkyl group having 3 to 8 carbon atoms, and a cycloalkylalkyl group having 5 to 8 carbon atoms; X represents any one of a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, a methoxy group, an ethoxy group, and a halogen atom; and n represents an integer of 1 to 3.) Examples of the compound represented by formula (17) include a diester of 4-phenylphenol ethylene glycol ether and cyclohexanecarboxylic acid, a diester of 4-phenylphenol diethylene glycol ether and lauric acid, a diester of 4-phenylphenol triethylene glycol ether and cyclohexanecarboxylic acid, a diester of 4-phenylphenol ethylene glycol ether and octanoic acid, a diester of 4-phenylphenol ethylene glycol ether and nonanoic acid, a diester of 4-phenylphenol ethylene glycol ether and decanoic acid, and a diester of 4-phenylphenol ethylene glycol ether and myristic acid.

[0058] Furthermore, a reversible thermochromic composition of the heat-coloring type (which develops color upon heating and loses color upon cooling) using a gallic acid ester (JP-B No. 51-44706, JP-A No. 2003-253149) or the like as an electron-accepting compound can also be applied (see Figure 3).

[0059] The above-mentioned reversible thermochromic composition is a compatible solution containing the above-mentioned components (A), (B), and (C) as essential components, and the proportions of each component depend on the concentration, discoloration temperature, discoloration form, and type of each component. Generally, the component ratios that achieve the desired properties are in the range of 1 part of component (A) to 0.1 to 100, preferably 0.1 to 50, and more preferably 0.5 to 20, of component (B), and 5 to 200, preferably 5 to 100, and more preferably 10 to 100, of component (C) (all of the above proportions are in parts by mass).

[0060] Examples of photochromic materials include conventionally known photochromic compounds such as spirooxazine derivatives, spiropyran derivatives, and naphthopyran derivatives, which develop color when irradiated with sunlight, ultraviolet light, or blue light having a peak emission wavelength in the range of 400 to 495 nm, and lose color when the irradiation is stopped. Examples of spirooxazine derivatives include conventionally known indolinospirobenzoxazine compounds, indolinospironaphthoxazine compounds, indolinospirophenanthrooxazine compounds, and indolinospiroquinolinoxazine compounds. Further, examples of photochromic compounds having optical memory properties (color memory and photochromic properties) include conventionally known fulgide derivatives and diarylethene derivatives.

[0061] Furthermore, as the photochromic material, a reversible photochromic composition in which the above photochromic compound is dissolved in various oligomers can also be used. The oligomers include styrene-based oligomers, acrylic-based oligomers, terpene-based oligomers, and terpene-phenol-based oligomers. Examples of styrene oligomers include low molecular weight polystyrene, styrene-α-methylstyrene copolymer, α-methylstyrene polymer, and copolymer of α-methylstyrene and vinyltoluene. Examples of the acrylic oligomer include acrylic acid ester copolymers. Examples of terpene oligomers include α-pinene polymers, β-pinene polymers, and d-limonene polymers. An example of the terpene phenol oligomer is an α-pinene-phenol copolymer. By dissolving the photochromic compound in various oligomers, it is possible to improve the light resistance of the photochromic compound, as well as to improve the color density and adjust the color change sensitivity.

[0062] The styrene-based oligomer used has a mass-average molecular weight of 200 to 6000, preferably 200 to 4000. If the mass-average molecular weight of the styrene-based oligomer exceeds 6000, color retention occurs upon light irradiation, the color density tends to be low, and it tends to be difficult to adjust the color change sensitivity. On the other hand, if the mass-average molecular weight is less than 200, the amount of contained monomer increases, resulting in a lack of stability and a tendency to impair light resistance. The acrylic oligomer used has a mass-average molecular weight of 12,000 or less, preferably 1,000 to 8,000, and more preferably 1,500 to 6,000. If the mass-average molecular weight of the acrylic oligomer exceeds 12,000, it tends to be difficult to adjust the discoloration sensitivity. On the other hand, if the mass-average molecular weight is less than 1,000, the amount of contained monomer increases, resulting in a lack of stability, which tends to result in a low color density and a loss of lightfastness. The terpene oligomer used has a mass-average molecular weight of 250 to 4000, preferably 300 to 4000. If the mass-average molecular weight of the terpene oligomer exceeds 4000, color retention occurs upon light irradiation, the color density tends to be low, and it tends to be difficult to adjust the color change sensitivity. On the other hand, if the mass-average molecular weight is less than 250, the amount of contained monomer increases, resulting in a lack of stability and a tendency to impair lightfastness. The terpene phenol oligomer used has a mass-average molecular weight of 200 to 2000, preferably 500 to 1200. If the mass-average molecular weight of the terpene phenol oligomer exceeds 2000, it tends to be difficult to adjust the discoloration sensitivity. On the other hand, if the mass-average molecular weight is less than 200, the amount of contained monomer increases, resulting in a lack of stability and a tendency for the color density to decrease. The mass average molecular weight of the oligomer is a value measured by GPC (gel permeation chromatography). The above oligomers can be used alone or in a suitable mixture of two or more.

[0063] The mass ratio of the photochromic compound to the styrene-based oligomer or the photochromic compound to the acrylic oligomer is preferably 1:1 to 1:10000, and more preferably 1:5 to 1:500. The mass ratio of the photochromic compound to the terpene oligomer is preferably 1:1 to 1:5000, and more preferably 1:5 to 1:500. The mass ratio of the photochromic compound to the terpene phenol oligomer is preferably 1:1 to 1:50, and more preferably 1:2 to 1:30. When the mass ratio of the photochromic compound to the oligomer is within the above range, the photochromic compound can fully exhibit its color-developing and color-decoloring function, and the color density can be easily obtained.

[0064] Microencapsulation of microcapsule pigments can be performed by a variety of methods, including conventionally known isocyanate-based interfacial polymerization methods, in situ polymerization methods such as melamine-formalin-based polymerization methods, in-liquid curing coating methods, phase separation methods from aqueous solutions, phase separation methods from organic solvents, melt-dispersion cooling methods, air suspension coating methods, and spray drying methods, and these methods are appropriately selected depending on the intended use. Examples of capsule materials include epoxy resins, urea resins, urethane resins, and isocyanate resins. Furthermore, depending on the purpose, a secondary resin film may be provided on the surface of the microcapsules to impart durability or modify the surface properties for practical use.

[0065] Furthermore, as the colorant applied to the present invention, pigments, dyes, or resin particles containing functional materials such as thermochromic materials and photochromic materials can be used. Examples of resin particles containing a pigment include resin particles in which the pigment is uniformly dispersed, and resin particles whose surfaces are coated with a pigment. The pigment is not particularly limited as long as it can be dispersed in or adsorbed to the resin that constitutes the resin particles, and the above-mentioned inorganic pigments, organic pigments, luster pigments, fluorescent pigments, phosphorescent pigments, etc. The above-mentioned pigments may be surface-treated by various conventionally known methods in order to improve their dispersibility or adsorption to the resin that constitutes the resin particles. Examples of resins that constitute the resin particles include polystyrene, acrylic resin, epoxy resin, melamine resin, polyester, polyvinyl chloride, polybutadiene, benzoguanamine resin, polyamide, urethane resin, polymethyl methacrylate, acrylic-urethane copolymer resin, phenolic resin, polyethylene, polypropylene, polyacrylonitrile, polyacetal, ethylene-propylene copolymer resin, ethylene-vinyl acetate copolymer resin, styrene-acrylic copolymer resin, styrene-butadiene copolymer resin, styrene-acrylonitrile copolymer resin, and acrylonitrile-butadiene copolymer resin.

[0066] Examples of resin particles containing a dye include resin particles in which a dye is homogeneously dissolved or dispersed in the resin particles, and resin particles in which a dye is dyed onto the resin particles. The dye is not particularly limited as long as it can be dissolved, dispersed, or dyed in the resin that constitutes the resin particles, and in addition to acid dyes, basic dyes, and direct dyes, the above-mentioned oil-soluble dyes and disperse dyes can be used.

[0067] Examples of acid dyes include New Coccine (CI 16255), Tartrazine (CI 19140), Acid Blue Black 10B (CI 20470), Guinea Green (CI 42085), Brilliant Blue FCF (CI 42090), Acid Violet 6B (CI 42640), Soluble Blue (CI 42755), Naphthalene Green (CI 44025), Eosin (CI 45380), Phloxine (CI 45410), Erythrosine (CI 45430), Nigrosine (CI 50420), and Acid Flavin (CI 56205). Examples of basic dyes include chrysoidine (CI 11270), methyl violet FN (CI 42535), crystal violet (CI 42555), malachite green (CI 42000), Victoria blue FB (CI 44045), rhodamine B (CI 45170), acridine orange NS (CI 46005), and methylene blue B (CI 52015). Examples of direct dyes include Congo Red (CI 22120), Direct Sky Blue 5B (CI 24400), Violet BB (CI 27905), Direct Deep Black EX (CI 30235), Kayalas Black G Conc (CI 35225), Direct Fast Black G (CI 35255), and Phthalocyanine Blue (CI 74180).

[0068] When the resin particles contain a dye, the resin constituting the resin particles is not particularly limited, and the same resin as that constituting the resin particles containing the pigment described above can be used, but among these resins, thermosetting resins are preferred. Thermosetting resins are superior to thermoplastic resins in solvent resistance and heat resistance, and also in migration resistance of the contained dye, making them suitable because they can prevent the dye from leaching out of the resin. Examples of thermosetting resins include epoxy resins, epoxy acrylate resins, xylene resins, toluene resins, guanamine resins, benzoguanamine resins, melamine resins, urethane resins, phenolic resins, alkyd resins, polyamides, polyimides, polyamide esters, urea resins, silicone resins, and unsaturated polyesters. Among these resins, guanamine resins and melamine resins are preferred because they can further suppress the elution of dyes.

[0069] Examples of resin particles containing a thermochromic material or a photochromic material include resin particles in which the above-mentioned thermochromic material or photochromic material is uniformly dispersed in the resin particles.

[0070] The resin constituting the resin particles is not particularly limited as long as it is a thermoplastic resin or a thermosetting resin, and examples thereof include thermoplastic resins such as polystyrene, acrylic resin, polyester, polyvinyl chloride, polybutadiene, polymethyl methacrylate, acrylic-urethane copolymer resin, polyethylene, polypropylene, polyacrylonitrile, polyacetal, ethylene-propylene copolymer resin, ethylene-vinyl acetate copolymer resin, styrene-acrylic copolymer resin, styrene-butadiene copolymer resin, styrene-acrylonitrile copolymer resin, and acrylonitrile-butadiene copolymer resin; Examples of suitable resins include thermosetting resins such as epoxy resins, epoxy acrylate resins, xylene resins, toluene resins, guanamine resins, benzoguanamine resins, melamine resins, urethane resins, phenolic resins, alkyd resins, polyamides, polyimides, polyamide esters, urea resins, silicone resins, and unsaturated polyesters.

[0071] The resin particles can be produced by a pulverization method, a spray drying method, or a polymerization method in which polymerization is carried out in an aqueous or oily medium in the presence of a pigment, a dye, a thermochromic material, or a photochromic material, such as a suspension polymerization method, a suspension polycondensation method, a dispersion polymerization method, or an emulsion polymerization method. The shape of the resin particles is not particularly limited, and resin particles having a spherical shape such as a perfect sphere, an oval sphere, or an approximately spherical shape, a polygonal shape, or a flat shape can be used, but it is preferable to use spherical resin particles.

[0072] The pigment, microencapsulated pigment encapsulating a pigment or dye, or resin particles containing a pigment or dye are preferably blended in an amount of 0.5 to 15% by mass, more preferably 1 to 10% by mass, based on the total amount of the ink composition. If the blending ratio of the pigment, microencapsulated pigment, or resin particles exceeds 15% by mass, the viscosity of the ink composition tends to increase, which reduces the ink dischargeability of a writing instrument containing the ink composition and tends to impair writing performance. On the other hand, if the blending ratio is less than 0.5% by mass, it becomes difficult to achieve a writing density suitable for the writing instrument. The microencapsulated pigment encapsulating a thermochromic or photochromic material, or the resin particles containing a thermochromic or photochromic material, are preferably blended in an amount of 5 to 40% by mass, more preferably 10 to 40% by mass, and even more preferably 15 to 35% by mass, based on the total amount of the ink composition. If the blending ratio of the microencapsulated pigment or resin particles exceeds 40% by mass, the viscosity of the ink composition tends to increase, the ink dischargeability of a writing instrument containing the ink composition tends to decrease, and writing performance tends to be impaired. On the other hand, if the blending ratio is less than 5% by mass, it is difficult to achieve suitable color change properties and suitable writing density for a writing instrument, and it is difficult to fully satisfy the color change function.

[0073] Furthermore, as the colorant applied to the present invention, solid resin particles with no voids inside the particles, hollow resin particles with voids inside the particles, etc. can also be used. Hollow resin particles have voids inside the particles, which are filled with air, and the outer shell of the particles is a cross-linked polymer layer. Light incident on hollow resin particles is reflected at the interface between the polymer layer and the dispersion medium in which the hollow resin particles are dispersed, and at the interface between the polymer layer and the void, making them more susceptible to light scattering than solid resin particles. Therefore, hollow resin particles are white in color and can be used as pigments with a hiding effect. Furthermore, due to their hollow structure with voids inside the resin, they have the characteristic of having a lower specific gravity than general pigments. Examples of resins that constitute the polymer layer of the outer shell of solid resin particles or hollow resin particles include polyethylene, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polystyrene, polymethyl methacrylate, polyacrylonitrile, polyamide, polycarbonate, polyacetal, polyethylene terephthalate, polyurethane, maleic acid resin, styrene-acrylonitrile copolymer resin, acrylonitrile-butadiene-styrene copolymer, styrene-acrylic copolymer resin, styrene-butadiene copolymer, and modified products thereof.

[0074] The solid or hollow resin particles are preferably blended in an amount of 5 to 15% by mass, more preferably 5 to 10% by mass, based on the total amount of the ink composition. If the blending ratio of the solid or hollow resin particles exceeds 15% by mass, the viscosity of the ink composition tends to increase, which reduces the ink dischargeability of a writing instrument containing the ink composition and tends to impair writing performance. On the other hand, if the blending ratio is less than 5% by mass, it becomes difficult to achieve the desired writing density and hiding effect for a writing instrument.

[0075] The above-mentioned reversible thermochromic composition or reversible photochromic composition can be encapsulated in microcapsules to form a reversible thermochromic microcapsule pigment or a reversible photochromic microcapsule pigment, or dispersed in a thermoplastic resin or thermosetting resin to form reversible thermochromic resin particles or reversible photochromic resin particles, but the above-mentioned reversible thermochromic composition or reversible photochromic composition is preferably encapsulated in microcapsules to be used as a microcapsule pigment. This is because encapsulation in microcapsules allows for the formation of a chemically and physically stable pigment, and furthermore, the reversible thermochromic composition or reversible photochromic composition can maintain the same composition and exhibit the same effects under various use conditions.

[0076] The reversible thermochromic microcapsule pigment or reversible photochromic microcapsule pigment preferably has a mass ratio of inclusions to wall film of 7:1 to 1:1, and by having the mass ratio of inclusions to wall film within the above range, a decrease in color density and vividness during color development is prevented.The mass ratio of inclusions to wall film is more preferably 6:1 to 1:1. If the ratio of the inclusions to the wall film exceeds the above range, the wall film of the microcapsule pigment becomes thin and is easily destroyed by heat or pressure, while if the ratio of the wall film to the inclusions exceeds the above range, the color density and vividness of the developed color tend to decrease.

[0077] The average particle size of the colorant used in the present invention is preferably 0.01 to 5 μm, more preferably 0.05 to 4 μm, even more preferably 0.1 to 3 μm, and particularly preferably 0.5 to 3 μm. If the average particle size of the colorant exceeds 5 μm, it becomes difficult to obtain good ink ejection properties when used in a writing instrument. On the other hand, if the average particle size is less than 0.01 μm, it becomes difficult to achieve high-density color development. The average particle size was measured by determining the particle area using image analysis particle size distribution measurement software (manufactured by Mountec Co., Ltd., product name: MacView), calculating the diameter equivalent to a circle with a projected area (Heywood diameter) from the area of ​​the particle area, and measuring the average particle size of particles equivalent to a sphere with the same volume using this value. Furthermore, if the particle size of all or the majority of particles exceeds 0.2 μm, it is also possible to measure the average particle size of particles equivalent to an equal volume sphere using the Coulter method using a particle size distribution analyzer (product name: Multisizer 4e, manufactured by Beckman Coulter, Inc.). Furthermore, the volumetric particle size and average particle size may be measured using a calibrated laser diffraction / scattering particle size distribution analyzer (manufactured by HORIBA, Ltd., product name: LA-300) based on values ​​measured using the above software or a measuring device using the Coulter method.

[0078] The vehicle applicable to the present invention is an aqueous vehicle containing water and, if necessary, an organic solvent. The water is not particularly limited, and examples thereof include tap water, ion-exchanged water, ultrafiltered water, and distilled water. Examples of organic solvents include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thioethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone. The amount of water, or water and organic solvent, blended in the ink composition is preferably 30 to 80% by mass, more preferably 40 to 70% by mass.

[0079] The vehicle used in the present invention contains a cationic polymer selected from the above formulas (1) to (5). The cationic polymer is an amine-based polymer compound and is water-soluble. Here, the polymer (polymer compound) includes not only polymers formed by polymerizing multiple units of one type of monomer, but also copolymers formed by polymerizing multiple units of two or more types of monomer. The cationic polymer described above adsorbs to the surface of the colorant in the ink composition, thereby positively charging the colorant.

[0080] In formula (1), the cationic polymer in which n1 is 0 is represented by the following formula (18), and is a polymer having allylamine repeating units having a primary amine cation. [ka] (In the formula, n represents a natural number.) In addition, in formula (1), a cationic polymer in which n1 is 1 is represented by the following formula (19), and is a polymer having repeating units of an acid salt of allylamine having a primary amine cation. [ka] (In the formula, X1 represents hydrochloric acid, amidosulfuric acid, or acetic acid, and n represents a natural number.) The mass average molecular weight of the cationic polymer represented by formula (1) is in the range of 500 to 200,000, and n represents the degree of polymerization required to achieve a mass average molecular weight of 500 to 200,000. Specific examples of the cationic polymer represented by formula (1) include products manufactured by Nittobo Medical Co., Ltd., product names: PAA-01, PAA-03, PAA-05, PAA-08, PAA-15, PAA-15C, PAA-25, PAA-HCl-01, PAA-HCl-03, PAA-HCl-05, PAA-HCl-3L, PAA-HCl-10L, PAA-SA, etc.

[0081] In formula (2), the cationic polymer in which n2a and n2b are 0 is represented by the following formula (20), and is a copolymer consisting of allylamine having a primary amine cation and diallylamine having a secondary amine cation. [ka] (In the formula, m and n each independently represent a natural number.) Furthermore, in formula (2), a cationic polymer in which n2a is 1 and n2b is 0 is represented by the following formula (21), which is a copolymer consisting of an acid salt of allylamine having a primary amine cation and a diallylamine having a secondary amine cation. [ka] (In the formula, X 2a represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. Furthermore, in formula (2), a cationic polymer in which n2a is 0 and n2b is 1 is represented by the following formula (22), which is a copolymer consisting of an acid salt of allylamine having a primary amine cation and diallylamine having a secondary amine cation. [ka] (In the formula, X 2b represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. Furthermore, in formula (2), a cationic polymer in which n2a and n2b are 1 is represented by the following formula (23), which indicates a copolymer consisting of an acid salt of allylamine having a primary amine cation and an acid salt of diallylamine having a secondary amine cation. [ka] (In the formula, X 2a and X 2b each independently represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. The mass average molecular weight of the cationic polymer represented by formula (2) is in the range of 500 to 200,000, and m and n represent the degree of polymerization required to achieve a mass average molecular weight of 500 to 200,000. Specific examples of the cationic polymer represented by formula (2) include products manufactured by Nittobo Medical Co., Ltd., such as PAA-D11-HCl, PAA-D41-HCl, PAA-D19-HCl, and PAA-D19A.

[0082] In formula (3), the cationic polymer in which n3a and n3b ​​are 0 is represented by the following formula (24), which is a copolymer of allylamine having a primary amine cation and dimethylallylamine having a tertiary amine cation. [ka] (In the formula, m and n each independently represent a natural number.) Furthermore, in formula (3), a cationic polymer in which n3a is 1 and n3b ​​is 0 is represented by the following formula (25), which is a copolymer consisting of an acid salt of allylamine having a primary amine cation and dimethylallylamine having a tertiary amine cation. [ka] (In the formula, X 3a represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. Furthermore, in formula (3), a cationic polymer in which n3a is 0 and n3b ​​is 1 is represented by the following formula (26), which is a copolymer of an allylamine having a primary amine cation and an acid salt of dimethylallylamine having a tertiary amine cation. [ka] (In the formula, X 3b represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. Furthermore, in formula (3), the cationic polymer in which n3a and n3b ​​are 1 is represented by the following formula (27), which is a copolymer consisting of an acid salt of polyallylamine having a primary amine cation and an acid salt of dimethylallylamine having a tertiary amine cation. [ka] (In the formula, X 3a and X 3b each independently represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. The mass average molecular weight of the cationic polymer represented by formula (3) is in the range of 500 to 200,000, and m and n represent the degree of polymerization required to achieve a mass average molecular weight of 500 to 200,000. Specific examples of the cationic polymer represented by formula (3) include products manufactured by Nittobo Medical Co., Ltd., product names: PAA-1112 and PAA-1112CL.

[0083] In formula (4), a cationic polymer in which n4 is 0 and R1 is a hydrogen atom is represented by the following formula (28), and is a polymer having a diallylamine repeating unit having a secondary amine cation. [ka] (In the formula, n represents a natural number.) Furthermore, in formula (4), a cationic polymer in which n4 is 1 and R1 is a hydrogen atom is represented by the following formula (29), which is a polymer having a repeating unit of a diallylamine acid salt having a secondary amine cation. [ka] (In the formula, X4 represents hydrochloric acid, amidosulfuric acid, or acetic acid, and n represents a natural number.) Furthermore, in formula (4), a cationic polymer in which n4 is 0 and R1 is a linear or branched alkyl group having 1 to 3 carbon atoms is represented by the following formula (30), which is a polymer having an alkyldiallylamine having a tertiary amine cation as a repeating unit. [ka] (In the formula, R1′ represents a linear or branched alkyl group having 1 to 3 carbon atoms, and n represents a natural number.) Furthermore, a cationic polymer in which n4 is 1 and R1 is a linear or branched alkyl group having 1 to 3 carbon atoms in formula (4) is represented by the following formula (31), and is a polymer having repeating units of an acid salt of an alkyldiallylamine having a tertiary amine cation. [ka] (In the formula, R1′ represents a linear or branched alkyl group having 1 to 3 carbon atoms, X4 represents hydrochloric acid, amidosulfuric acid, or acetic acid, and n represents a natural number.) Examples of the linear or branched alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. The mass average molecular weight of the cationic polymer represented by formula (4) is in the range of 500 to 200,000, and n represents the degree of polymerization required to achieve a mass average molecular weight of 500 to 200,000. Specific examples of the cationic polymer represented by formula (4) include products manufactured by Nittobo Medical Co., Ltd., such as PAS-21, PAS-21CL, PAS-M-1L, PAS-M-1, PAS-22SA-40, and PAS-M-1A.

[0084] The cationic polymer represented by formula (5) is a polymer having a repeating unit of a diallyldialkylammonium salt having a quaternary amine cation. [ka] (In the formula, R2 and R3 each independently represent a linear or branched alkyl group having 1 to 3 carbon atoms, X5 represents a chlorine atom, CH3SO4, or C2H5SO4, and n represents a natural number.) Examples of the linear or branched alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, and an isopropyl group. The mass average molecular weight of the cationic polymer represented by formula (5) is in the range of 10,000 to 300,000, and n represents the degree of polymerization required to achieve a mass average molecular weight of 10,000 to 300,000. Specific examples of the cationic polymer represented by formula (5) include products manufactured by Nittobo Medical Co., Ltd., such as PAS-H-5L, PAS-H-10L, and PAS-24.

[0085] Furthermore, a polymer represented by the following formula (32) can also be used as the cationic polymer. The polymer represented by formula (32) is a polymer in which the primary amines of the cationic polymer in formula (1) where n1 is 0 are partially substituted with groups having a carbonyl group. [ka] (In the formula, R4 represents a linear or branched alkyl group having 1 to 3 carbon atoms, a linear or branched alkoxy group having 1 to 3 carbon atoms, or an amino group, and m and n each independently represent a natural number.) Examples of the linear or branched alkyl group having 1 to 3 carbon atoms include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, etc. Examples of the linear or branched alkoxy group having 1 to 3 carbon atoms include a methoxy group, an ethoxy group, an n-propoxy group, and an isopropoxy group. The mass average molecular weight of the cationic polymer represented by formula (32) is in the range of 500 to 200,000, and m and n represent the degree of polymerization required to achieve a mass average molecular weight of 500 to 200,000. Specific examples of the cationic polymer represented by formula (32) include products manufactured by Nittobo Medical Co., Ltd., such as PAA-U5000, PAA-U7030, PAA-AC5050A, PAA-N5000, and PAA-N5050CL.

[0086] The cationic polymer used in the present invention is preferably a cationic polymer represented by formula (1) in which n1 is 0, or n1 is 1 and X1 is hydrochloric acid or amidosulfuric acid. In the cationic polymer represented by formula (2), n2a and n2b are preferably 0 or 1, and n2a and n2b are preferably 0 or 1, and X 2a and X 2b are the same, and n2a and n2b are 0, or n2a and n2b are 1, and X 2a and X 2b More preferably, is hydrochloric acid or acetic acid. In the cationic polymer represented by formula (3), n3a and n3b ​​are preferably 0 or 1, and n3a and n3b ​​are preferably 0 or 1, and X 3a and X 3b are the same, and n3a and n3b ​​are 0, or n3a and n3b ​​are 1, and X 3a and X 3b More preferably, is hydrochloric acid. In the cationic polymer represented by formula (4), R1 is preferably a hydrogen atom or a methyl group, and when R1 is a hydrogen atom, n4 is preferably 0, or n4 is 1 and X4 is hydrochloric acid; or when R1 is a methyl group, n4 is preferably 1 and X4 is hydrochloric acid or amidosulfuric acid. In the cationic polymer represented by formula (5), it is preferable that R2 and R3 are methyl groups, or that one of R2 and R3 is a methyl group and the other is an ethyl group; when R2 and R3 are methyl groups, X5 is a chlorine atom; or when one of R2 and R3 is a methyl group and the other is an ethyl group, X5 is more preferably C2H5SO4; and it is even more preferable that R2 and R3 are methyl groups and X5 is a chlorine atom. In the cationic polymer represented by formula (32), R4 is preferably any one of a methyl group, a methoxy group, and an amino group. The cationic polymers described above are preferably used because they have excellent adsorption properties to the surface of the colorant and can more stably charge the colorant with a positive charge.

[0087] The mass-average molecular weight of the cationic polymers represented by formulas (1) to (4) used in the present invention is not particularly limited as long as it is in the range of 500 to 200,000, but is preferably in the range of 800 to 100,000, and more preferably in the range of 1,000 to 50,000. The mass-average molecular weight of the cationic polymer represented by formula (5) is not particularly limited as long as it is in the range of 10,000 to 300,000, but is preferably in the range of 25,000 to 250,000, and more preferably in the range of 50,000 to 250,000.

[0088] The vehicle used in the present invention further contains an acrylic polymer dispersant in addition to the cationic polymer. The combined use of the cationic polymer and the acrylic polymer dispersant creates an ionic interaction between the colorant positively charged by the cationic polymer and the anionic acrylic polymer dispersant, which causes the acrylic polymer dispersant to loosely bridge the positively charged colorants, forming loose aggregates of the colorants. This prevents the colorants from adhering to each other and flocculating, preventing separation of the colorants and allowing them to be easily redispersed even if they do separate. When the ink composition is placed in a writing instrument and used in practice, this prevents the colorant from floating up or settling, resulting in darkening or lightening of handwriting. In particular, this prevents the colorant from settling down and lightening of handwriting when a writing instrument containing an ink composition using a colorant with a high specific gravity is subjected to external stimuli such as vibrations in an upright position or is stored for a long period of time. The above-mentioned effect is effective for reversible thermochromic microcapsule pigments, which have a larger average particle diameter than general-purpose pigments and are particularly prone to have a large specific gravity due to the substances encapsulated in the microcapsules, and is preferably used because it suppresses separation of the microcapsule pigment in the ink composition and allows it to be easily redispersed even if it does separate.

[0089] The acrylic polymer dispersant is preferably an acrylic polymer dispersant having a carboxy group, more preferably an acrylic polymer dispersant having a comb structure with a carboxy group in the side chain, and even more preferably an acrylic polymer dispersant having a comb structure with multiple carboxy groups in the side chain. A specific example of an acrylic polymer dispersant having a comb structure and multiple carboxy groups in the side chains is Solsperse 43000, a product name manufactured by Lubrizol Japan Co., Ltd.

[0090] Among the cationic polymers applicable to the present invention, it is preferable that in the cationic polymer represented by formula (1), n1 is 0, or n1 is 1, and X1 is hydrochloric acid or amidosulfuric acid, because this has excellent ionic interaction with the acrylic polymer dispersant. In addition, in the cationic polymer represented by formula (2), n2a and n2b are 1, and X 2a and X 2b is preferably hydrochloric acid or acetic acid. In the cationic polymer represented by formula (4), it is preferable that R1 is a hydrogen atom and n4 is 0, or that R1 is a hydrogen atom, n4 is 1, and X4 is hydrochloric acid. In the cationic polymer represented by formula (32), R4 is preferably an amino group. The cationic polymers described above have excellent ionic interactions with the acrylic polymer dispersant, and can further improve the effect of suppressing separation of the colorant and easily redispersing it even if it does separate. Furthermore, when the ink composition is placed in a writing implement and put into practical use, they further suppress the floating or settling of the colorant, which causes the writing to darken or lighten. In particular, when the specific gravity of the colorant is high, they further suppress the settling of the colorant, which causes the writing to lighten when the writing implement is subjected to external stimuli such as vibrations in an upright position or when the writing implement is stored for a long period of time, thereby enabling the formation of good handwriting. Therefore, they are preferably used.

[0091] Furthermore, the cationic polymers represented by formulas (1) to (5) are not easily affected by excessive temperature changes and are strongly adsorbed to the colorant surface, and the loose aggregates formed by ionic interactions with the acrylic polymer dispersant are also not easily affected by excessive temperature changes, so that the colorant in the aqueous ink composition of the present invention is inhibited from aggregating regardless of the temperature environment in which it is stored. Therefore, when the ink composition is frozen and thawed and the state of the ink composition changes from liquid to solid or from solid to liquid, the colorant is inhibited from aggregating and separating. When the ink composition is stored in a writing instrument and used in practice, even when it is left in a low temperature range below 0°C where the ink freezes or in a high temperature range, for example, at 50°C, the colorant is inhibited from aggregating and reducing the ink fluidity, and the ink dischargeability from the pen tip of the writing instrument is less likely to be impaired. The above-mentioned effects are effective for reversible thermochromic microcapsule pigments or reversible thermochromic resin particles that tend to aggregate over time and form a hard cake layer, and the ink composition is preferably used because it inhibits aggregation of the reversible thermochromic microcapsule pigments or reversible thermochromic resin particles, allows them to be easily redispersed, and provides excellent ink ejection from the pen tip of a writing instrument containing the ink composition.

[0092] In the aqueous ink composition of the present invention, the mass ratio of the cationic polymer to the acrylic polymer dispersant is preferably 1:2.5 to 1:16, and more preferably 1:3 to 1:12. When the mass ratio of the cationic polymer to the acrylic polymer dispersant is within the above range, the cohesive force of the loose aggregates of the colorant formed by the cationic polymer and the acrylic polymer dispersant is improved, allowing the colorant to be stably dispersed in the ink composition and preventing the colorant from floating up or settling and becoming localized.

[0093] Furthermore, the ionic interaction between the cationic polymer and the acrylic polymer dispersant in the aqueous ink composition of the present invention is also effective for colorants that tend to settle in the ink composition, such as pigments or resin particles with a high specific gravity, and has the effect of suppressing the settling and localization of these colorants, which would otherwise cause the handwriting to become lighter in color. Examples of pigments with a high specific gravity include titanium oxide and microcapsule pigments encapsulating it, luster pigments and microcapsule pigments encapsulating it, and reversible thermochromic microcapsule pigments encapsulating a reversible thermochromic composition with a large hysteresis width (ΔH). Examples of resin particles with a high specific gravity include resin particles containing titanium oxide, resin particles containing a luster pigment, and reversible thermochromic resin particles containing a reversible thermochromic composition with a large hysteresis (ΔH). The colorant applicable to the present invention is preferably a reversible thermochromic microencapsulated pigment in which the component (C) in the reversible thermochromic composition is in the range of 60 to 90 mass % relative to the total amount of the reversible thermochromic composition, the mass average molecular weight of component (C) is 250 or more, and the specific gravity of the reversible thermochromic microencapsulated pigment in a fully colored state at 20°C relative to water is 1.05 to 1.20. The above-mentioned reversible thermochromic microencapsulated pigments exhibit a large hysteresis width (ΔH), and such reversible thermochromic microencapsulated pigments can be decolorized by heating and can maintain the decolorized state within a specific temperature range, and therefore are widely used not only in the field of writing instruments but also in a wide range of other fields. However, reversible thermochromic microencapsulated pigments with a large hysteresis width (ΔH) often use a compound having two or more benzene rings in the molecule as component (c), which tends to have a large specific gravity and to easily settle and separate in the ink composition. In particular, when external stimuli such as vibration are applied or when the pigment is stored for a long period of time, the colorant settles and separates, and further, redispersion is difficult. However, the aqueous ink composition of the present invention can suppress separation of the colorant even when a colorant with a large specific gravity, such as the above-mentioned reversible thermochromic microcapsule pigment, is used as the colorant. Furthermore, even when the ink composition is subjected to external stimuli such as vibration or when stored for a long period of time, separation of the colorant is suppressed, and even if separation occurs, the colorant can be easily redispersed, making the aqueous ink composition suitable for use. Considering the dispersion stability of the above-mentioned reversible thermochromic microencapsulated pigment in the aqueous ink composition of the present invention, it is more preferable that the component (C) in the reversible thermochromic composition is in the range of 65 to 85 mass % based on the total amount of the reversible thermochromic composition, that the mass average molecular weight of component (C) is 250 or more, and that the specific gravity of the reversible thermochromic microencapsulated pigment in the fully colored state at 20°C relative to water is 1.05 to 1.20. In the above-mentioned reversible thermochromic microcapsules, the specific gravity of the reversible thermochromic microencapsulated pigment in the fully colored state is preferably 1.10 to 1.20, and more preferably 1.12 to 1.15. Furthermore, a reversible thermochromic microencapsulated pigment is even more preferred in which the component (C) in the reversible thermochromic composition is in the range of 70 to 85 mass % relative to the total amount of the reversible thermochromic composition, the mass average molecular weight of component (C) is 250 or more, and the specific gravity of the reversible thermochromic microencapsulated pigment in a fully colored state at 20°C relative to water is 1.05 to 1.20; in the above-mentioned reversible thermochromic microcapsules, the specific gravity of the reversible thermochromic microencapsulated pigment in a fully colored state is preferably 1.10 to 1.20, and more preferably 1.12 to 1.15. When the proportion of component (c) in the reversible thermochromic composition relative to the total amount of the reversible thermochromic composition is within the above range, even if the temperature of the reversible thermochromic composition is repeatedly changed, the reversible thermochromic function of the composition, which becomes discolored in a temperature range above the high-temperature discoloration point (complete discoloration temperature) and becomes colored in a temperature range below the low-temperature discoloration point (complete color development temperature), is unlikely to be impaired, and the color density when colored is clear and sufficient as a colorant. The specific gravity of the reversible thermochromic microcapsule pigment can be measured by the following method.

[0094] (Method for measuring specific gravity of reversible thermochromic microcapsule pigment) 1. Put 30 ml of glycerin aqueous solution and 1 g of fully colored reversible thermochromic microcapsule pigment into a screw cap bottle and mix to prepare a reversible thermochromic microcapsule pigment dispersion. 2. 30 ml of the above microcapsule pigment dispersion is adjusted to 20°C and centrifuged at 1,000 rpm for 30 seconds. A refrigerated tabletop centrifuge (manufactured by Kokusan Co., Ltd., product name: H103N) can be used as the centrifuge. 3. Observe the microcapsule pigment dispersion. If it is confirmed that most of the microcapsule pigment has settled to the bottom of the beaker, repeat steps 1 and 2 using an aqueous solution with a higher glycerin concentration than the glycerin aqueous solution used at this time, and observe the state of the dispersion. If it is confirmed that most of the microencapsulated pigment has risen to the surface of the liquid, repeat steps 1 and 2 using an aqueous solution with a lower glycerin concentration than the glycerin aqueous solution used at this time, and observe the state of the dispersion. The above series of operations is repeated until it is visually confirmed that the majority of the microencapsulated pigment does not sink to the surface or float, but that the glycerin aqueous solution is uniformly colored except for the surface and the area near the bottom of the screw cap bottle. When this state is observed, the specific gravity of the glycerin aqueous solution is measured and used as the specific gravity of the reversible thermochromic microencapsulated pigment. The specific gravity of the glycerin aqueous solution can be measured by the hydrometer method described in JIS K0061, Section 7.1, using an aqueous solution adjusted to 20°C.

[0095] Furthermore, by blending a specific gravity adjuster into the vehicle used in the present invention, it is possible to further suppress the colorant from floating up or settling and becoming localized in the ink composition, even while the ink composition has a low viscosity, thereby improving the dispersion stability of the colorant. The dispersion stability of a colorant is maximized when the difference in specific gravity between the vehicle and the colorant is minimal, and the specific gravity adjuster brings the specific gravity of the vehicle closer to that of the colorant. The specific gravity of the vehicle depends on the specific gravity of the water-soluble substance dissolved in the vehicle and the amount added. Adding and dissolving a larger specific gravity adjuster in the vehicle can increase the specific gravity of the vehicle.

[0096] Examples of specific gravity adjusters include oxyacids of Group 6 elements having an atomic weight of 90 to 185 and salts thereof. Such a specific gravity adjuster can adjust the specific gravity of the vehicle to be closer to that of a colorant with a large specific gravity, and can suppress the colorant from settling and the resulting lightening of handwriting due to external stimuli such as vibration or long-term storage, even while the ink composition has a low viscosity, and is therefore preferably used.

[0097] The above-mentioned oxygen acids and salts thereof are selected from the group consisting of oxygen acids of transition metal elements and salts thereof, and the oxygen acid ions thereof are said to form tetrahedrons or octahedrons in which oxygen atoms are usually 4- or 6-coordinated to metal atoms, etc. The tetrahedral or octahedral units may be single units, or may be polyacids having a structure in which they are bonded via edges or vertices, and their salts, called polyacid salts. Polyacids are polyacids formed by the condensation of oxyacids of metal elements, but polyacids composed of only one type of metal and in which all the condensed anions are of the same type are called isopolyacids, and polyacids in which two or more types of anions are condensed are called heteropolyacids. The respective salts are called isopolyacid salts and heteropolyacid salts. The above polyacids include isopolyacids, heteropolyacids, etc., and the above polyacid salts include isopolyacids, heteropolyacids, etc.

[0098] Examples of the specific gravity adjuster include a single oxygen acid and its salt, an isopoly acid and its salt, and a heteropoly acid and its salt. Examples of the single oxygen acid include molybdic acid and tungstic acid, and examples of the salt of the single oxygen acid include sodium molybdate, potassium molybdate, ammonium molybdate, sodium tungstate, potassium tungstate, ammonium tungstate, lithium tungstate, and magnesium tungstate. Examples of isopolyacids include metamolybdic acid, paramolybdic acid, metatungstic acid, paratungstic acid, and isotungstic acid. Examples of isopolyacid salts include sodium metamolybdate, potassium metamolybdate, ammonium metamolybdate, sodium paramolybdate, potassium paramolybdate, ammonium paramolybdate, sodium metatungstate, potassium metatungstate, ammonium metatungstate, barium metatungstate, sodium paratungstate, and sodium isotungstate. Examples of heteropolyacids include molybdophosphoric acid, molybdosilicic acid, tungstophosphoric acid, and tungstosilicic acid, and examples of heteropolyacid salts include sodium molybdophosphate, sodium molybdosilicate, sodium tungstophosphate, and sodium tungstosilicate. The above oxygen acids and salts thereof can be used singly or in a suitable mixture of two or more.

[0099] Among the above-mentioned specific gravity adjusters, metatungstic acid, paratungstic acid, sodium metatungstate, potassium metatungstate, ammonium metatungstate, barium metatungstate, sodium paratungstate, sodium isotungstate, tungstophosphoric acid, tungstosilicic acid, sodium tungstophosphate, and sodium tungstosilicate are preferred, and sodium isotungstate, sodium metatungstate, and sodium paratungstate are more preferred. The above-mentioned sodium isotungstate, sodium metatungstate, and sodium paratungstate are not only highly safe but also have high specific gravities themselves, so that it is easy to adjust the liquid to have a high specific gravity depending on the amount added, and therefore they are preferably used.

[0100] The specific gravity adjuster is preferably blended in the range of 2 to 20% by mass, more preferably 5 to 15% by mass, of the total amount of the ink composition. If the blending ratio of the specific gravity adjuster exceeds 20% by mass, the colorant tends to aggregate. On the other hand, if the blending ratio is less than 2% by mass, the effect of adjusting the specific gravity of the vehicle becomes poor. The mass ratio of the colorant to the specific gravity adjuster is preferably 1:0.05 to 1:4, more preferably 1:0.075 to 1:2, and even more preferably 1:0.1 to 1:1.5.

[0101] The vehicle containing the specific gravity adjuster is particularly effective for colorants such as pigments or resin particles having a high specific gravity, and even though the ink composition has a low viscosity, it can suppress sedimentation of the colorant in the ink composition when it is subjected to external stimuli such as vibration or when it is stored for a long period of time, thereby improving the dispersion stability of the colorant. Examples of pigments with a high specific gravity include titanium oxide and microcapsule pigments encapsulating titanium oxide, luster pigments and microcapsule pigments encapsulating luster pigments, and reversible thermochromic microcapsule pigments encapsulating reversible thermochromic compositions with a large hysteresis (ΔH). Examples of resin particles with a high specific gravity include resin particles containing titanium oxide, resin particles containing a luster pigment, and reversible thermochromic resin particles containing a reversible thermochromic composition with a large hysteresis (ΔH). The specific gravity of the colorant, such as the pigment or resin particles, is preferably 1.05 to 1.20, more preferably 1.10 to 1.20, and even more preferably 1.12 to 1.15, when water is used as the reference substance at 20° C. When the specific gravity of the colorant is within the above range, the dispersion stability of the pigment or resin particles in the ink composition containing the specific gravity adjuster is further improved, and when the ink composition is subjected to external stimuli such as vibration or is stored for a long period of time, sedimentation and localization of the colorant can be further suppressed, even though the vehicle has a low viscosity. The specific gravity of the colorant such as the pigment or resin particles can be measured by the same procedure as in the "Method for measuring the specific gravity of a reversible thermochromic microencapsulated pigment" described above. The color development and fluidity of handwriting produced by the ink composition of the present invention are easily affected by the particle size of the colorant. Colorants having an average particle size outside the above-mentioned range tend to have low color density or poor fluidity, but the content of these colorants in the total colorant content is small, and their effect on the performance of the ink composition is minimal. Colorants having an average particle size outside such a range have a lighter or heavier specific gravity than colorants having an average particle size within the above-mentioned range, and in the glycerin aqueous solution prepared as described above, they will either settle to the bottom of the screw cap bottle or rise to the surface. However, since colorants having an average particle size within the above-mentioned range will float in the glycerin aqueous solution, an ink composition with excellent dispersion stability and good color development of handwriting can be obtained by using the specific gravity of the aqueous solution at this time as the specific gravity of the vehicle.

[0102] Furthermore, the vehicle containing the above-mentioned specific gravity adjuster has a specific gravity in the range of 1.00 to 1.30 at 20°C when water is used as the reference substance, and the specific gravity is preferably 1.05 to 1.20, and more preferably 1.08 to 1.18. Furthermore, the specific gravity of the vehicle is preferably 0.90 to 1.20 times, and more preferably 0.95 to 1.10 times, the specific gravity of the colorant such as the pigment or resin particles. When the specific gravity of the vehicle is within the above range and the ratio of the specific gravity of the vehicle to the specific gravity of the colorant is within the above range, when the ink composition is subjected to external stimuli such as vibration or when stored for a long period of time, the viscosity of the vehicle can be kept low, while still further suppressing the colorant from settling and becoming localized in the ink composition, thereby further improving the dispersion stability of the colorant.

[0103] Furthermore, by blending a water-soluble organic solvent into the vehicle used in the present invention, evaporation of water from the ink composition can be suppressed, fluctuations in the specific gravity of the ink composition can be prevented, good dispersion stability of the colorant can be maintained, and the structure of the loose aggregates formed by the cationic polymer and the acrylic polymer dispersant can be stabilized. Examples of water-soluble organic solvents include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, diethanolamine, monoethanolamine, ethylene glycol, diethylene glycol, thioethylene glycol, polyethylene glycol, propylene glycol, butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, propylene glycol monobutyl ether, ethylene glycol monomethyl ether acetate, sulfolane, 2-pyrrolidone, and N-methyl-2-pyrrolidone. When a reversible thermochromic microcapsule pigment or reversible thermochromic resin particles with a large hysteresis width (ΔH) is used as the colorant, the specific gravity of the reversible thermochromic microcapsule pigment or reversible thermochromic resin particles is greater than 1, and when adjusting the specific gravity of the ink composition, using a water-soluble organic solvent with a specific gravity greater than that of water makes it easier to adjust the specific gravity. Therefore, it is preferable to use glycerin or the like with a specific gravity of greater than 1.1 as the water-soluble organic solvent.

[0104] The water-soluble organic solvent is preferably blended in an amount of 1 to 40% by mass, more preferably 5 to 30% by mass, and even more preferably 10 to 25% by mass of the total amount of the ink composition. If the blending ratio of the water-soluble organic solvent exceeds 40% by mass, the ink viscosity tends to increase, which reduces the ink dischargeability of a writing instrument containing the ink composition and tends to impair writing performance. On the other hand, if the blending ratio is less than 1% by mass, the effect of suppressing water evaporation is poor, making it difficult to prevent fluctuations in the specific gravity of the ink composition.

[0105] Furthermore, by blending a water-soluble resin into the vehicle used in the present invention, it is possible to impart adhesion to the paper surface and viscosity, and also to improve the stability of the cationic polymer and acrylic polymer dispersant in the ink composition. Examples of the water-soluble resin include water-soluble alkyd resin, acrylic resin, styrene-maleic acid copolymer, cellulose derivative, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin. Furthermore, as the water-soluble resin, polyvinyl alcohol is preferred because it provides excellent stability to the acrylic polymer dispersant, partially saponified polyvinyl alcohol is more preferred, and partially saponified polyvinyl alcohol having a degree of saponification of 70 to 89 mol% is even more preferred. Specific examples of water-soluble resins include those manufactured by Nippon Vaccination Poval Co., Ltd., product names: J Poval JP Series, JL Series, JR Series, Mitsubishi Chemical Corporation, product name: G-type GOHSENOL, K-type GOHSENOL, Examples include PVA203, 205, 210, 217, 217E, 217EE, 220, 220E, 224, 224E, 235, 403, 405, 420, 420H, 424H, 505, L-8, L-9, L-9-78, and L-10, manufactured by Kuraray Co., Ltd.

[0106] The water-soluble resin is preferably blended in an amount of 0.1 to 1.5% by mass, more preferably 0.5 to 1% by mass, based on the total amount of the ink composition. By blending the water-soluble resin in this range, the stability of the acrylic polymer dispersant is improved, and when a reversible thermochromic microcapsule pigment or reversible thermochromic resin particles is used as the colorant, the color development and color change properties of the colorant are less likely to be impaired.

[0107] The water-based ink composition of the present invention may further contain, as necessary, extenders such as kaolin, talc, mica, clay, bentonite, calcium carbonate, aluminum hydroxide, sericite, and potassium titanate; wetting agents such as fluorine-based surfactants and nonionic surfactants; acrylic resins, urethane resins, styrene-butadiene resins, alkyd resins, sulfamide resins, maleic acid resins, polyvinyl acetate, ethylene-vinyl acetate copolymer resins, vinyl chloride-vinyl acetate copolymer resins, styrene-maleic acid ester copolymer resins, styrene-acrylonitrile copolymer resins, cyanate-modified polyalkylene glycols, ester gums, xylene resins, urea resins, urea aldehyde resins, phenolic resins, alkylphenolic resins, terpene phenolic resins, rosin resins and hydrogenated compounds thereof, rosin phenolic resins, polyvinyl alkyl ethers, polyamides, polyolefins, nylon resins, and polyesters. and cyclohexanone-based resins, and other water-soluble resins used as fixing agents; emulsions of water-insoluble resins; resin particles made of polyolefin, acrylic resin, nylon resin, silicone resin, urethane resin, fluororesin, etc.; pH adjusters such as inorganic salts such as ammonia, sodium carbonate, sodium phosphate, sodium hydroxide, sodium acetate, and organic basic compounds such as water-soluble amine compounds; rust inhibitors such as benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, and saponin; wetting agents such as urea, nonionic surfactants, reduced or non-reduced starch hydrolysates, disaccharides such as trehalose, oligosaccharides, sucrose, cyclodextrin, glucose, dextrin, sorbitol, mannitol, and sodium pyrophosphate; antifoaming agents, viscosity adjusters, preservatives, and antifungal agents may also be blended.

[0108] The aqueous ink composition of the present invention can be produced by any conventionally known method, specifically by blending the required amounts of the above-mentioned components and mixing them using various stirrers such as a propeller stirrer, a homodisper, or a homomixer, or various dispersers such as a bead mill.

[0109] When a reversible thermochromic microencapsulated pigment or reversible thermochromic resin particle, or a reversible photochromic microencapsulated pigment or reversible photochromic resin particle is used as the colorant applied in the present invention, an enantiotropic color change from colored (1) to colored (2) can be exhibited by blending the above-mentioned inorganic pigments, organic pigments, photoluminescent pigments, fluorescent pigments, phosphorescent pigments, or other pigments, or non-color-changing colorants such as dyes, or microencapsulated pigments encapsulating these, or resin particles containing the above-mentioned non-color-changing colorants, into the microencapsulated pigment or resin particle, or into the ink composition.

[0110] The viscosity of the aqueous ink composition of the present invention, measured at a rotation speed of 30 rpm in an environment of 20° C., is preferably 1 to 20 mPa·s, more preferably 1 to 10 mPa·s, and even more preferably 1 to 7 mPa·s. By having the viscosity of the ink composition within the above range, localization of the colorant in the ink composition is suppressed, and the ink discharge properties from the pen tip of a writing instrument containing the ink composition are improved, thereby suppressing writing defects such as smearing and skipped lines, and making it possible to obtain an ink composition that can produce handwriting with good color development. The viscosity is a value measured by placing the ink composition in an environment of 20°C using a BL-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., product name: TVB-M type viscometer, L-type rotor).

[0111] The surface tension of the aqueous ink composition of the present invention is preferably 25 to 50 mN / m, more preferably 25 to 45 mN / m, and even more preferably 30 to 45 mN / m, in an environment at 20°C. When the surface tension of the ink composition is within the above range, writing is less likely to smear when using a writing instrument containing the ink composition. Furthermore, ink discharge properties are not impaired even when the ink is left in a temperature range below 0°C, where the ink freezes, or in a high-temperature environment, such as 50°C, and variations in writing density and writing width due to storage and usage environments are less likely to occur. Furthermore, bleeding of writing and strike-through onto the paper surface are easily suppressed, and the ink composition can have improved wettability on the paper surface. The surface tension is a value measured by a surface tension measuring instrument (manufactured by Kyowa Interface Science Co., Ltd., product name: DY-300) by placing the ink composition in an environment of 20°C using a glass plate by a vertical plate method.

[0112] Furthermore, the pH of the aqueous ink composition of the present invention is preferably 3 to 8, more preferably 4 to 7, and even more preferably 5 to 7. By keeping the pH of the ink composition within the above range, aggregation or sedimentation of the colorant contained in the ink composition, particularly the reversible thermochromic microencapsulated pigment or reversible thermochromic resin particles, at low temperatures can be suppressed. Furthermore, if the pH exceeds 8, the ink dischargeability is likely to be impaired when a writing instrument containing the ink composition is left at low temperatures, i.e., at temperatures where the ink freezes. On the other hand, if the pH is less than 3, when a reversible thermochromic microencapsulated pigment or reversible thermochromic resin particles are used as the colorant, the color development of the reversible thermochromic composition becomes strong, which can easily lead to the problem of color residue remaining when the ink is erased. The pH value was measured by placing the ink composition in an environment of 20°C using a pH meter (manufactured by DKK-TOA Corporation, product name: IM-40S).

[0113] The water-based ink composition of the present invention is used by being contained in a writing instrument. Examples of writing implements include ballpoint pens, marking pens, fountain pens, brush pens, calligraphy pens, and other various writing implements.

[0114] When the aqueous ink composition of the present invention is used in a ballpoint pen, the structure and shape of the ballpoint pen itself are not particularly limited, and it is used, for example, by filling it into a ballpoint pen refill or ballpoint pen equipped with a ballpoint pen tip and an ink filling mechanism.

[0115] A ballpoint pen tip consists of a tip body and a ball attached to the front end of the tip body, and examples include tips in which the ball is held in a ball-holding portion formed by deforming the tip body made of a metal pipe by pressing the outer surface inward near the tip, tips in which the ball is held in a ball-holding portion formed by cutting with a drill or the like on a tip body made of a metal material, tips in which a resin ball receiving seat is provided inside a metal or plastic tip, and tips in which the ball held in the tip is urged forward by a spring body. The material of the tip body and the ball is not particularly limited, and examples thereof include cemented carbide (super hard), stainless steel, ruby, ceramic, resin, and rubber. The diameter of the ball is preferably 0.1 to 3.0 mm, more preferably 0.2 to 2.0 mm, and even more preferably 0.3 to 1.0 mm. The ball may also be subjected to a surface treatment such as a DLC coating.

[0116] An example of the ink filling mechanism is an ink reservoir that can be directly filled with the ink composition. The ink reservoir may be, for example, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon, or a tubular body made of metal. A ballpoint pen refill (hereinafter sometimes referred to as "refill") can be formed by connecting a ballpoint pen tip directly or via a connecting member to an ink reservoir and directly filling the ink reservoir with ink. A ballpoint pen can be formed by storing this refill in a barrel.

[0117] The ink reservoir is filled with an ink backflow preventer at the rear end thereof, which may be a liquid stopper or a solid stopper. The liquid plug is made of a non-volatile liquid and / or a hardly-volatile liquid, examples of which include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, and fatty acid-modified silicone oil. The non-volatile liquid and / or the hardly-volatile liquid may be used alone or in a suitable mixture of two or more kinds.

[0118] It is preferable to add a thickener to the non-volatile liquid and / or the hardly-volatile liquid to thicken it to a suitable viscosity. Examples of thickeners include clay-based thickeners such as silica with a hydrophobic surface treatment, fine particle silica with a methylated surface, aluminum silicate, swellable mica, hydrophobically treated bentonite or montmorillonite, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate, dextrin-based compounds such as tribenzylidene sorbitol, fatty acid amides, amide-modified polyethylene wax, hydrogenated castor oil, and fatty acid dextrins, and cellulose-based compounds.

[0119] Examples of solid stoppers include solid stoppers made of polyethylene, polypropylene, polymethylpentene, and the like. As the ink backflow preventer, the above-mentioned liquid stopper and solid stopper can be used in combination.

[0120] In addition, by using the barrel itself as the ink filling mechanism, filling ink directly into the barrel, and attaching a ballpoint pen tip to the front end of the barrel, it is possible to form a ballpoint pen equipped with a ballpoint pen tip and an ink filling mechanism.

[0121] If the ink filled in the ink filling mechanism has a low viscosity, a ballpoint pen equipped with a ballpoint pen tip and an ink filling mechanism may further include an ink supply mechanism for supplying the ink filled in the ink filling mechanism to the pen tip. The ink supply mechanism is not particularly limited, and examples include: (1) a mechanism that has an ink guide core made of a fiber bundle or the like as an ink flow rate regulator and supplies ink to the pen tip through this; (2) a mechanism that has a comb-shaped ink flow rate regulator and supplies ink to the pen tip through this; and (3) a mechanism that supplies ink to the pen tip through a pen core consisting of multiple disks arranged in parallel with comb-shaped intervals, with slit-shaped ink guide grooves running vertically through the disks in the axial direction and wider ventilation grooves than the grooves, and an ink guide core arranged in the axial center to guide ink from the ink filling mechanism to the pen tip. The material for the pen core is not particularly limited as long as it is a synthetic resin that can be injection molded into a structure in which multiple discs are arranged in a comb-like groove pattern. Examples of synthetic resins include general-purpose polycarbonate, polypropylene, polyethylene, and acrylonitrile-butadiene-styrene copolymer resin (ABS resin). In particular, acrylonitrile-butadiene-styrene copolymer resin (ABS resin) is preferably used because it has high moldability and is easy to obtain pen core performance.

[0122] When a ballpoint pen is provided with the ink supply mechanism, the ink filling mechanism may be an ink reservoir that can be filled with ink, in addition to the ink reservoir and barrel. The ink occlusion body is a fiber bundle formed by bundling crimped fibers in the longitudinal direction, and is placed inside a covering such as a plastic cylinder or film, and is configured so that the porosity is adjusted to be in the range of approximately 40 to 90%.

[0123] A ballpoint pen refill including a ballpoint pen tip, an ink filling mechanism, and an ink supply mechanism can also be formed by accommodating an ink occluder impregnated with ink in an ink reservoir, providing an ink supply mechanism at the front end of the ink reservoir so as to connect to the ink occluder, and connecting a ballpoint pen tip to the ink supply mechanism directly or via a connecting member. Alternatively, a ballpoint pen refill can also be formed by accommodating an ink occluder impregnated with ink in an ink reservoir, providing an ink supply mechanism inside the ink reservoir so as to connect to the ink occluder, and connecting a ballpoint pen tip to the ink reservoir directly or via a connecting member.

[0124] Specific examples of the configuration of a ballpoint pen containing the ink composition according to the present invention include: (1) a ballpoint pen having an ink reservoir filled with ink in a barrel, to which a ballpoint pen tip is connected either directly or via a connecting member, and in which an ink backflow preventer is filled at the end face of the ink reservoir; (2) a ballpoint pen in which ink is directly filled in the barrel and which is provided with a mechanism for supplying ink to the pen tip by using a comb-shaped ink flow regulator or an ink guide core made of a fiber bundle or the like as an ink flow regulator; (3) a ballpoint pen in which ink is directly filled in the barrel and which is provided with a mechanism for supplying ink to the pen tip via the above-mentioned pen core; and (4) a ballpoint pen in which an ink occlusion body made of a fiber bundle impregnated with ink is contained in the barrel and which is provided with a mechanism for supplying ink to the pen tip by using an ink guide core made of a fiber bundle or the like as an ink flow regulator.

[0125] Furthermore, when the ink composition according to the present invention is used in a marking pen, the structure and shape of the marking pen itself are not particularly limited, and it may be used, for example, by filling it into a marking pen refill or a marking pen equipped with a marking pen tip and an ink filling mechanism.

[0126] Examples of marking pen tips include conventionally used porous members with interconnected pores, such as resin-processed fibers, fused heat-melting fibers, and felt, with a porosity selected from a range of approximately 30 to 70%, or extrusion-molded synthetic resin bodies with multiple ink outlet holes extending in the axial direction, and one end of the tip can be processed into a shape appropriate for the purpose, such as a bullet shape, a rectangle, or a chisel shape, for practical use.

[0127] An example of the ink filling mechanism is an ink occlusion body that can be filled with ink. The ink occlusion body is a fiber bundle formed by bundling crimped fibers in the longitudinal direction, and is contained within a covering such as a plastic cylinder or film, with the porosity adjusted to a range of approximately 40 to 90%. A marking pen can be formed by housing an ink-impregnated ink reservoir inside the barrel and connecting the marking pen tip to the barrel directly or via a connecting member so that it is connected to the ink reservoir. Furthermore, a marking pen refill (hereinafter sometimes referred to as a "refill") can be formed by storing an ink occlusion body impregnated with ink in an ink reservoir and connecting a marking pen tip to the ink reservoir directly or via a connecting member. A marking pen can be formed by storing this refill in a barrel. The ink reservoir may be, for example, a molded body made of a thermoplastic resin such as polyethylene, polypropylene, polyethylene terephthalate, or nylon, or a tubular body made of metal.

[0128] A marking pen equipped with a marking pen tip and an ink filling mechanism may further include an ink supply mechanism for supplying the ink composition filled in the ink filling mechanism to the pen tip. The ink supply mechanism is not particularly limited, and examples include: (1) a mechanism that has an ink guide core made of a fiber bundle or the like as an ink flow regulator and supplies ink to the pen tip through this; (2) a mechanism that has a comb-shaped ink flow regulator and supplies ink to the pen tip through this; (3) a mechanism that supplies ink to the pen tip through a pen core consisting of a number of disks arranged in parallel with comb-shaped intervals, with slit-shaped ink guide grooves running axially through the disks and wider ventilation grooves than the grooves, and an ink guide core arranged in the axial center to guide ink from the ink filling mechanism to the pen tip; and (4) a mechanism that has an ink flow regulator with a valve mechanism and supplies ink to the pen tip by opening the valve. The material for the pen core is not particularly limited as long as it is a synthetic resin that can be injection molded into a structure in which multiple discs are arranged in a comb-like groove pattern. Examples of synthetic resins include general-purpose polycarbonate, polypropylene, polyethylene, and acrylonitrile-butadiene-styrene copolymer resin (ABS resin). In particular, acrylonitrile-butadiene-styrene copolymer resin (ABS resin) is preferably used because it has high moldability and is easy to obtain pen core performance. The valve mechanism can be a conventional, general-purpose pumping type that opens when the tip is pressed, and is preferably set to a spring pressure that can be pressed and released by the pressure of the writing pen.

[0129] When the marking pen is provided with an ink supply mechanism, the ink filling mechanism may be an ink reservoir that can be directly filled with ink, in addition to the ink occlusion body described above. Also, the barrel itself may serve as the ink filling mechanism, allowing ink to be directly filled. Alternatively, a marking pen refill including a marking pen tip, an ink filling mechanism, and an ink supply mechanism can be formed by accommodating an ink occluder impregnated with ink in an ink reservoir, providing an ink supply mechanism at the front end of the ink reservoir so as to connect to the ink occluder, and connecting a marking pen tip to the ink supply mechanism directly or via a connecting member. Alternatively, a marking pen refill can be formed by accommodating an ink occluder impregnated with ink in an ink reservoir, providing an ink supply mechanism inside the ink reservoir so as to connect to the ink occluder, and connecting a marking pen tip to the ink reservoir so as to connect to the ink supply mechanism directly or via a connecting member.

[0130] Specific configurations of marking pens containing the ink composition of the present invention include: (1) a marking pen in which an ink occlusion body made of a fiber bundle impregnated with ink is contained in a barrel, and a marking pen tip made of a fiber processed body or a resin molded body with capillary gaps formed therein is connected to the barrel directly or via a connecting member so that the ink occlusion body and the tip are connected; (2) a marking pen in which ink is directly filled in the barrel, and which is provided with a mechanism for supplying ink to the pen tip by using an ink flow regulator such as a comb-shaped ink flow regulator or an ink guide core made of a fiber bundle or the like as an ink flow regulator; and (3) a marking pen in which ink is directly filled in the barrel, and a marking pen tip made of a fiber bundle or the like as an ink flow regulator. Examples include: (4) a marking pen that is filled with ink and is equipped with a mechanism that supplies ink to the pen tip via the pen core; (5) a marking pen that is equipped with an ink reservoir that is connected to a tip and an ink container via a valve mechanism that opens when the tip is pressed, and in which ink is directly filled into the ink container; and (6) a marking pen that has an ink reservoir that contains an ink absorbing body made of a fiber bundle impregnated with ink within its barrel, and in which a marking pen tip made of a fiber processed body or a resin molded body with a capillary gap formed therein is connected to the ink reservoir directly or via a connecting member so that the ink absorbing body and the tip are connected.

[0131] Furthermore, when a ballpoint pen or marking pen is directly filled with ink, an agitator such as an agitating ball for agitating the ink may be built into the ink reservoir or barrel into which the ink is filled in order to facilitate re-dispersion of the colorant. Examples of the shape of the agitator include a spherical body and a rod-like body. The material of the agitator is not particularly limited, and examples thereof include metal, ceramic, resin, and glass.

[0132] Furthermore, the ballpoint pen or marking pen described above may be provided with a detachable ink cartridge. In this case, after the ink composition contained in the ink cartridge of the writing instrument is used up, the ink cartridge can be replaced with a new cartridge and used again. Ink cartridges include those that double as the barrel that constitutes the writing instrument when connected to the writing instrument body, and those that cover and protect the barrel (rear barrel) after being connected to the writing instrument body. In the latter case, the ink cartridge may be used alone, or may be one in which the writing instrument body and ink cartridge are connected in the writing instrument before use, or one that is stored in the barrel in a disconnected state so that the user of the writing instrument can connect the ink cartridge in the barrel when using it to start use.

[0133] Furthermore, it is preferable that the writing instrument having the above-described configuration be provided with a cap that is attached to cover the writing tip (tip tip), or with a retraction mechanism that allows the writing tip to protrude and retract from the writing instrument body (barrel), thereby preventing the writing tip from drying out and becoming unable to write, or preventing the writing tip from becoming contaminated or damaged. A writing instrument with a retractable mechanism can be any writing instrument that has a structure in which the writing tip is stored in a barrel exposed to the outside air and the writing tip protrudes from the barrel opening when the retractable mechanism is activated.For example, a writing instrument with a retractable mechanism (retractable writing instrument) can be made by producing the above-mentioned ballpoint pen refill or marking pen refill, storing the refill in a barrel, and configuring it so that the writing tip protrudes from the barrel opening when the retractable mechanism is activated. Furthermore, when a retractable mechanism is provided in a ballpoint pen-type writing instrument, it can be a composite type retractable writing instrument (retractable ballpoint pen) that contains multiple ballpoint pen refills in the barrel and causes the writing tip of one of the ballpoint pen refills to protrude and retract from the barrel opening by activation of the retractable mechanism.

[0134] Examples of retraction mechanisms include: (1) a side-slide retraction mechanism in which an operating part (clip) that can move back and forth in the radial direction protrudes radially outward from the rear side wall of the barrel, and the writing tip is retracted from the front end opening of the barrel by sliding the operating part forward; (2) a rear-end knock retraction mechanism in which the operating part at the rear end of the barrel is pressed forward to cause the writing tip to retract from the front end opening of the barrel; (3) a side-knock retraction mechanism in which the operating part that protrudes from the outer surface of the barrel side wall is pressed radially inward to cause the writing tip to retract from the front end opening of the barrel; and (4) a rotary retraction mechanism in which the operating part at the rear of the barrel is rotated to cause the writing tip to retract from the front end opening of the barrel.

[0135] Furthermore, the shapes of ballpoint pens and marking pens are not limited to the configurations described above, and they may be equipped with tips of different shapes, or with pen tips that dispense ink of different colors, or they may be composite writing instruments (double-headed, retractable pen tip, etc.) that are equipped with tips of different shapes and dispense ink of different colors from each tip.

[0136] A preferred writing instrument containing the aqueous ink composition of the present invention is a writing instrument having a marking pen tip made of a resin-processed or resin-molded body having capillary gaps formed therein as a pen tip. The aqueous ink composition of the present invention forms loose aggregates of the colorant, thereby preventing aggregation in the capillary gaps of the marking pen tip and allowing the ink to be stably discharged from the pen tip of the writing instrument. Therefore, the aqueous ink composition of the present invention is suitably used as a writing instrument (marking pen) that can produce good handwriting while preventing writing defects such as smearing.

[0010] A more preferred writing instrument containing the aqueous ink composition of the present invention comprises a marking pen tip made of a resin-processed or molded resin body having capillary gaps formed therein as a pen tip, the marking pen tip being attached to the barrel of the writing instrument directly or via an intermediary member, and the barrel further contains an ink occlusion body made of a fiber bundle as an ink filling mechanism, the ink occlusion body and the marking pen tip being connected, and the ink occlusion body is impregnated with the ink composition. A writing instrument having the above-mentioned configuration is more preferably used because, in addition to the aforementioned effect of stably discharging ink from the pen tip of the writing instrument, the ink occlusion body made of a fiber bundle can more stably maintain the dispersibility of loose aggregates of colorant, suppressing darkening or lightening of handwriting and enabling the formation of even better handwriting with excellent color development.

[0137] Furthermore, since writing instruments containing aqueous ink compositions are prone to drying out of the writing tip, resulting in poor writing performance, it is preferable that the writing instrument having the above configuration be provided with a cap to cover the writing tip in order to prevent the writing tip from drying out.

[0138] In the present invention, when a reversibly thermochromic aqueous ink composition using a reversibly thermochromic microcapsule pigment or reversibly thermochromic resin particles as a colorant is contained in a writing instrument, handwriting obtained by writing on a surface using this writing instrument can be discolored by rubbing with a finger or by using a heating or cooling tool. Examples of the heating tool include an electrically heated discoloring tool equipped with a resistance heating element such as a PTC element, a heat discoloring tool filled with a medium such as hot water, a heat discoloring tool using steam or laser light, and the application of a hair dryer. However, friction members and friction bodies are preferred because they can change color in a simple manner. Examples of the cooling and heating device include an electrically operated cooling and heat-changing device using a Peltier element or the like, a cooling and heat-changing device filled with a refrigerant such as cold water or ice chips, a cooling agent, a refrigerator or a freezer, and the like.

[0139] As the friction member and friction body, an elastic body such as an elastomer or a plastic foam, which has a high elastic feel and can generate appropriate friction and frictional heat when rubbed, is preferred, but plastic molded bodies, stone, wood, metal, cloth, etc. can also be used. Although a general eraser used for erasing pencil marks may be used to rub the marks, eraser dust is generated during the rubbing, and therefore the above-mentioned friction member and friction body which hardly generate eraser dust are preferably used. Examples of materials for the friction member and friction body include silicone resin, SEBS resin (styrene-ethylene-butadiene-styrene block copolymer), etc. Silicone resin tends to adhere to areas that have been erased by rubbing, and handwriting tends to be repelled when writing is repeated, so SEBS resin is more preferably used.

[0140] The friction member or friction body may be a separate component of any shape from the writing instrument, but by providing it in the writing instrument, the writing instrument can be made highly portable. Also, a writing instrument set can be obtained by combining a writing instrument with a friction member or friction body of any shape that is separate from the writing instrument.

[0141] When the writing instrument is provided with a cap, the location where the friction member or friction body is provided is not particularly limited. For example, the cap itself may be formed from a friction member, or the barrel itself may be formed from a friction member. Furthermore, when a clip is provided, the clip itself may be formed from a friction member, or the friction member may be provided at the tip (top) of the cap or the rear end of the barrel (the part where the writing tip is not provided), etc. When the writing instrument is a retractable writing instrument, the location where the friction member or friction body is provided is not particularly limited. For example, the barrel itself may be formed from a friction member, and if a clip is further provided, the clip itself may be formed from a friction member, or the friction member may be provided at the rear end of the barrel (the part where the writing tip is not provided) or the knock portion, etc. [Example]

[0142] Examples are shown below, but the present invention is not limited to these. In the examples, "parts" means "parts by mass."

[0143] Preparation of reversible thermochromic microcapsule pigment A A reversible thermochromic composition consisting of 3 parts of 3',6'-bis[phenyl(3-methylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (A), 3 parts of 1,1-bis(4-hydroxyphenyl)-2-ethylhexane (B), 5 parts of 2,2-bis(4-hydroxyphenyl)hexafluoropropane (C), and 50 parts of 4-benzyloxyphenylethyl caprate (D) was added to a mixture of 35 parts of an aromatic isocyanate prepolymer and 40 parts of a cosolvent (D). The mixture was then emulsified in an 8% aqueous polyvinyl alcohol solution, heated and stirred, followed by the addition of 2.5 parts of a water-soluble aliphatic modified amine. A microcapsule dispersion was obtained by centrifuging the microcapsule dispersion to obtain a reversible thermochromic microcapsule pigment A having an average particle size of 1.9 μm. The reversible thermochromic microcapsule pigment A had a complete color development temperature t1 of -20°C and a complete decolorization temperature t4 of 60°C, and reversibly changed from blue to colorless with temperature change. Furthermore, the reversible thermochromic microencapsulated pigment A in a fully colored state had a specific gravity of 1.08 to 1.09 at 20°C relative to water.

[0144] Preparation of reversible thermochromic microcapsule pigment B A reversible thermochromic composition consisting of 3 parts of 3',6'-bis[phenyl(3-methylphenyl)amino]spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one (A), 3 parts of 1,1-bis(4-hydroxyphenyl)-2-ethylhexane (B), 5 parts of 2,2-bis(4-hydroxyphenyl)hexafluoropropane (C), and 50 parts of cyclohexylmethyl 4-biphenylacetate (D) was added to a mixture of 35 parts of an aromatic isocyanate prepolymer and 40 parts of a cosolvent (D). The mixture was then emulsified in an 8% aqueous polyvinyl alcohol solution, heated and stirred, followed by the addition of 2.5 parts of a water-soluble aliphatic modified amine. The mixture was further stirred to prepare a microcapsule dispersion. From the microcapsule dispersion, a reversible thermochromic microcapsule pigment B with an average particle size of 1.9 μm was obtained by centrifugation. The reversible thermochromic microencapsulated pigment B had a complete color development temperature t1 of -20°C and a complete decolorization temperature t4 of 62°C, and reversibly changed from blue to colorless with temperature change. Furthermore, the reversible thermochromic microencapsulated pigment B in a fully colored state had a specific gravity of 1.13 to 1.14 at 20°C relative to water.

[0145] reference Example 1 Preparation of Water-Based Ink Composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-03 (concentration: 20%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glycasil 2000), 25 parts of glycerin, 0.01 parts of an antifoaming agent, and 51.69 parts of water. Furthermore, 20 parts of resin particles (manufactured by Nippon Shokubai Co., Ltd., product name: Eposter MA-1002) were mixed with the above vehicle to prepare a water-based ink composition. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:8.

[0146] Creation of a filling-type writing implement The above-mentioned aqueous ink composition was impregnated into an ink reservoir made of polyester sliver covered with a synthetic resin film, and housed in a barrel made of polypropylene resin. A resin-processed pen body (bullet-shaped) made of polyester fiber was connected to the tip of the barrel via a holder, and a cap was attached to produce three fillable writing instruments (marking pens).

[0147] Example 1 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-03 (concentration: 20%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glycasil 2000), 25 parts of glycerin, 0.01 parts of an antifoaming agent, and 48.69 parts of water. Furthermore, 23 parts of reversible thermochromic microcapsule pigment A (previously cooled to -20°C or below to develop a blue color) was mixed with the vehicle to prepare a reversible thermochromic aqueous ink composition. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:8.

[0148] Fabrication of a filling-type writing implement (see Figure 4) The ink composition was impregnated into an ink occlusion body 2 made of polyester sliver coated with a synthetic resin film, and housed in a barrel 4 made of polypropylene resin. A resin-processed pen body 3 (chisel type) made of polyester fiber was connected to the tip of the barrel via a holder 5, and a cap 6 was attached to produce three fillable writing instruments 1 (marking pens). The top of the cap is fitted with a friction member 7 made of SEBS resin.

[0149] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0150] Example 2 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-03 (concentration: 20%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 10 parts of glycerin, 0.1 parts of an antifoaming agent, 1 part of a pH adjuster (10% aqueous phosphoric acid solution), and 54.6 parts of water, followed by adding and mixing 10 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment B (previously cooled to -20°C or below to develop a blue color) was mixed with the vehicle to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.155 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.01 to 1.02 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:8.

[0151] Fabrication of a filling-type writing implement (see Figure 5) The ink composition was impregnated into an ink absorbing body 2 made of polyester sliver coated with a synthetic resin film, and housed in a barrel 4 made of polypropylene resin. A resin-processed pen body 3 (bullet-shaped) made of an extrusion-molded polyacetal resin having multiple ink outlet holes extending in the axial direction was connected to the tip of the barrel via a holder 5, and a cap 6 was attached to produce three fillable writing instruments 1 (marking pens). The top of the cap is fitted with a friction member 7 made of SEBS resin.

[0152] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0153] Example 3 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-HCl-03 (concentration: 40%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 24 parts of glycerin, 0.1 parts of an antifoaming agent, and 45.6 parts of water, followed by adding and mixing 6 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment A (previously cooled to -20°C or below to develop a blue color) and the above vehicle were mixed to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.150 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.06 to 1.07 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:4.

[0154] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0155] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0156] Example 4 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-HCl-3L (concentration: 50%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 10 parts of glycerin, 0.1 parts of an antifoaming agent, 1 part of a pH adjuster (10% aqueous phosphoric acid solution), and 54.6 parts of water, followed by adding and mixing 10 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment B (previously cooled to -20°C or below to develop a blue color) was mixed with the vehicle to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.155 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.01 to 1.02 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:3.2.

[0157] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0158] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0159] Example5 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-D41-HCl (concentration: 40%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glycasil 2000), 25 parts of glycerin, 0.01 parts of an antifoaming agent, and 50.69 parts of water. Furthermore, 21 parts of reversible thermochromic microcapsule pigment A (previously cooled to -20°C or below to develop a blue color) and the above vehicle were mixed to prepare a reversible thermochromic aqueous ink composition. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:4.

[0160] Fabrication of a filling-type writing implement (see Figure 6) The above-mentioned aqueous ink composition was impregnated into an ink absorbing body 2 made of polyester sliver coated with a synthetic resin film, and housed in a barrel 4 made of polypropylene resin. A resin-processed pen body 3 (bullet-shaped) made of polyester fiber was connected to the tip of the barrel via a holder 5, and a cap 6 was attached to produce three fillable writing instruments 1 (marking pens). The top of the cap is fitted with a friction member 7 made of SEBS resin.

[0161] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0162] Example 6 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-D19-HCl (concentration: 21%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 24 parts of glycerin, 0.1 parts of an antifoaming agent, and 45.6 parts of water, followed by adding and mixing 6 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment A (previously cooled to -20°C or below to develop a blue color) and the above vehicle were mixed to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.150 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.06 to 1.07 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:7.6.

[0163] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0164] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0165] Example 7 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-D19A (concentration: 20%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 24 parts of glycerin, 0.1 parts of an antifoaming agent, and 45.6 parts of water, followed by adding and mixing 6 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment A (previously cooled to -20°C or below to develop a blue color) and the above vehicle were mixed to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.150 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.06 to 1.07 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:8.

[0166] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0167] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0168] Example 8 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAS-21CL (concentration: 25%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 24 parts of glycerin, 0.1 parts of an antifoaming agent, and 45.6 parts of water, followed by adding and mixing 6 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment A (previously cooled to -20°C or below to develop a blue color) and the above vehicle were mixed to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.150 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.06 to 1.07 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:6.4.

[0169] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0170] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0171] Example 9 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-AC5050A (concentration: 15%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 10 parts of glycerin, 0.1 parts of an antifoaming agent, 1 part of a pH adjuster (10% aqueous phosphoric acid solution), and 54.6 parts of water, followed by adding and mixing 10 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment B (previously cooled to -20°C or below to develop a blue color) was mixed with the vehicle to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.155 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.01 to 1.02 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:10.7.

[0172] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0173] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0174] Example 10 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAA-N5000 (concentration: 15%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 10 parts of glycerin, 0.1 parts of an antifoaming agent, 1 part of a pH adjuster (10% aqueous phosphoric acid solution), and 54.6 parts of water, followed by adding and mixing 10 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment B (previously cooled to -20°C or below to develop a blue color) was mixed with the vehicle to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.155 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.01 to 1.02 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:10.7.

[0175] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0176] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0177] Example 11 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAS-H-10L (concentration: 28%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 10 parts of glycerin, 0.1 parts of an antifoaming agent, 1 part of a pH adjuster (10% aqueous phosphoric acid solution), and 54.6 parts of water, followed by adding and mixing 10 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment B (previously cooled to -20°C or below to develop a blue color) was mixed with the vehicle to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.155 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.01 to 1.02 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:5.7.

[0178] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0179] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0180] Comparative Example 1 Preparation of Water-Based Ink Composition A vehicle was prepared by mixing 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glycasil 2000), 25 parts of glycerin, 0.01 parts of an antifoaming agent, and 54.19 parts of water. Furthermore, 20 parts of resin particles (manufactured by Nippon Shokubai Co., Ltd., product name: Eposter MA-1002) were mixed with the above vehicle to prepare a water-based ink composition.

[0181] Creation of a filling-type writing implement reference Three fill-type writing implements (marking pens) were prepared in the same manner as in Example 1.

[0182] Comparative Example 2 Preparation of reversible thermochromic water-based ink composition A vehicle was prepared by mixing 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glycasil 2000), 25 parts of glycerin, 0.01 parts of an antifoaming agent, and 51.19 parts of water. Furthermore, 23 parts of reversible thermochromic microcapsule pigment A (previously cooled to -20°C or below to develop a blue color) was mixed with the vehicle to prepare a reversible thermochromic aqueous ink composition.

[0183] Fabrication of a filling-type writing implement (see Figure 4) Example 1 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0184] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0185] Comparative Example 3 Preparation of reversible thermochromic water-based ink composition A cationic polymer (manufactured by Nittobo Medical Co., Ltd., product name: PAS-H-1L (concentration: 28%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 24 parts of glycerin, 0.1 parts of an antifoaming agent, and 45.6 parts of water, followed by adding and mixing 6 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment A (previously cooled to -20°C or below to develop a blue color) and the above vehicle were mixed to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.150 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.06 to 1.07 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:5.7.

[0186] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0187] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0188] Comparative Example 4 Preparation of reversible thermochromic water-based ink composition A cationic polymer (Nittobo Medical Co., Ltd., product name: PAA-1151 (concentration: 20%)) was mixed with water to prepare a 10% aqueous solution. A vehicle was prepared by mixing 2.5 parts of the above 10% aqueous solution, 0.4 parts of an acrylic polymer dispersant (manufactured by Lubrizol Japan Co., Ltd., product name: Solsperse 43000), 0.2 parts of a preservative (sodium 2-pyridinethiol 1-oxide) (manufactured by Lonza Japan Co., Ltd., product name: Sodium Omadine), 0.2 parts of a preservative (3-iodo-2-propynyl N-butylcarbamate) (manufactured by Lonza Japan Co., Ltd., product name: Glykasil 2000), 24 parts of glycerin, 0.1 parts of an antifoaming agent, and 45.6 parts of water, followed by adding and mixing 6 parts of a specific gravity adjuster (sodium polytungstate) (manufactured by Sometu Co., Ltd., product name: SPT). Furthermore, 21 parts of reversible thermochromic microcapsule pigment A (previously cooled to -20°C or below to develop a blue color) and the above vehicle were mixed to prepare a reversible thermochromic aqueous ink composition. The specific gravity of the vehicle was 1.150 when measured at 20° C. using water as the reference substance, and the specific gravity of the vehicle was 1.06 to 1.07 times that of the reversible thermochromic microencapsulated pigment. The mass ratio of cationic polymer to acrylic polymer dispersant was 1:8.

[0189] Fabrication of a filling-type writing implement (see Figure 5) Example 2 Three fill-type writing implements 1 (marking pens) were produced using the same procedure.

[0190] The marking pen was used to write on the paper to form blue letters (handwriting). The handwriting was blue at room temperature (20°C), and when rubbed with a friction member attached to the cap, the handwriting disappeared and became colorless. This state was maintained at room temperature, and when cooled to -20°C or below, the original blue color returned. The above-mentioned color change behavior could be reproduced repeatedly.

[0191] Viscosity measurement Reference example 1,Example 1 11 The viscosity of each of the aqueous ink compositions prepared in Comparative Examples 1 to 4 was measured using a BL-type rotational viscometer (manufactured by Toki Sangyo Co., Ltd., product name: TVB-M type viscometer with L-type rotor) at room temperature (20°C) and a rotation speed of 30 rpm.

[0192] surface tension measurement Reference example 1, Example 1 11 The surface tension of each of the aqueous ink compositions prepared in Comparative Examples 1 to 4 was measured using an automatic surface tensiometer (manufactured by Kyowa Interface Science Co., Ltd., product name: DY-300) by the vertical plate method using a glass plate at room temperature (20°C).

[0193] pH measurement Reference example 1, Example 1 11 The pH of each of the aqueous ink compositions prepared in Comparative Examples 1 to 4 was measured at room temperature (20°C) using a pH meter (manufactured by DKK-TOA Corporation, product name: IM-40S).

[0194] Evaluation of colorant dispersibility Reference example 1, Example 1 11 Each of the aqueous ink compositions prepared in Comparative Examples 1 to 4 was placed in a screw cap bottle and left to stand at room temperature (20°C) for 30 days, and the dispersibility of the colorant after standing was evaluated according to the following criteria. A: The colorant did not separate and could be easily redispersed. B: The colorant separated to form a hard cake layer and could not be redispersed.

[0195] Evaluation of initial writing performance reference The three writing instruments prepared in Example 1 and Comparative Example 1 were each written with A4 size black paper (manufactured by Nagatoya Shoten Co., Ltd., product name: Color Paper A4 Medium Weight (thickness: 0.09 mm, density: 80 g / m)) at room temperature (20°C). 2)) (vertical orientation), 15 oval-shaped circles with a major axis of approximately 15 mm and a minor axis of approximately 8 mm were written by hand in a spiral pattern so that the circles touched each other, with 15 circles per line, parallel to the short side of the paper, and this was done in 10 consecutive lines. Example 2 11 For each of the three writing implements prepared in Comparative Examples 2 to 4, the marking pen equipped with the bullet-shaped resin-processed pen body was used to handwrite 15 elliptical circles with a major axis of approximately 15 mm and a minor axis of approximately 8 mm in a spiral pattern, with the circles touching each other, in a direction parallel to the short edge of an A4-sized white paper (portrait) at room temperature (20°C). Ten lines were written in this manner. The marking pen equipped with the chisel-shaped resin-processed pen body was used to handwrite 15 cm straight lines in a direction parallel to the short edge of an A4-sized white paper (portrait) at room temperature (20°C) with the wide surface of the pen body pressed against the paper surface. Ten lines were written in this manner. Writing paper A conforming to the old JIS P3201 was used for the white paper. The resulting handwriting was then visually inspected and the initial writing performance was evaluated according to the following criteria. A: The handwriting was free of smudges and had good color development. B: Some fading was observed in the handwriting or the handwriting density was somewhat low, but this was at a level that would not cause any problems in practical use. C: Many smudges were observed in the handwriting, or the handwriting density was low, or writing was impossible, and handwriting with good color development was not obtained.

[0196] Vibration Test A cap was placed on one of the three writing instruments used in the writing test described above, and the writing instrument was placed in a shaker (manufactured by Taitec Co., Ltd., product name: Reciprocal Shaker) with the writing tip facing upward (upright position), and subjected to vertical vibration at 284 rpm for 12 hours in an environment of 40°C.

[0197] Temporal preservation Of the three writing instruments used in the writing test described above, the remaining two were capped and left to stand at room temperature (20°C) with the writing tip facing upward (upright position) for 7 days and 15 days.

[0198] Evaluation of writing performance after vibration test After the vibration test, each writing instrument was subjected to a writing test using the same test method as that used for the evaluation of initial writing performance described above. Next, the resulting handwriting was visually inspected, and the writing performance after the vibration test was evaluated according to the following criteria. A: The same level as the initial level was achieved, and handwriting with good color development was obtained. B: Compared to the initial state, some fading was observed in the handwriting or the handwriting density was slightly lower, but this was at a level that did not pose a problem in practical use. C: Compared to the initial state, many smudges were observed in the handwriting, or the handwriting density was low, or writing was impossible, and handwriting with good color development was not obtained.

[0199] Evaluation of writing performance after storage Each writing instrument stored at room temperature for 7 days and 15 days was subjected to a writing test using the same test method as used for the evaluation of initial writing performance described above. Next, the resulting handwriting was visually inspected, and the writing performance after storage was evaluated according to the following criteria. A: The same level as the initial level was achieved, and handwriting with good color development was obtained. B: Compared to the initial state, some fading was observed in the handwriting or the handwriting density was slightly lower, but this was at a level that did not pose a problem in practical use. C: Compared to the initial state, many smudges were observed in the handwriting, or the handwriting density was low, or writing was impossible, and handwriting with good color development was not obtained.

[0200] In Tables 1 and 2 below: Reference example 1, Example 1 11 , and the viscosity, surface tension and pH values ​​of each of the aqueous ink compositions prepared in Comparative Examples 1 to 4 are shown. In addition, Tables 3 and 4 show: Reference example 1, Example 1 11 , and the results of evaluation of the dispersibility of the colorant in each of the aqueous ink compositions prepared in Comparative Examples 1 to 4, as well as evaluation of the initial writing performance of each of the prepared writing instruments, evaluation of the writing performance after a vibration test, and evaluation of the writing performance after storage for 7 days and 15 days are shown.

[0201] [Table 1]

[0202] [Table 2]

[0203] [Table 3]

[0204] [Table 4] [Explanation of symbols]

[0205] t1 full color temperature t2 color development start temperature t3 decolorization start temperature t4 complete color erasure temperature T1 complete discoloration temperature T2 decolorization start temperature T3 color development start temperature T4 full color temperature ΔH Hysteresis width 1 writing implements 2. Ink occlusion body 3 Resin-coated pen body (tip) 4 shaft cylinder 5 Holder 6 Caps 7 Friction materials

Claims

1. An aqueous ink composition for a writing instrument, comprising: a reversible thermochromic microcapsule pigment encapsulating a reversible thermochromic composition comprising at least (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound, and (c) a reaction medium that controls the color reaction of the components (a) and (b); and a vehicle containing at least water, a cationic polymer selected from the following formulas (1) to (4) and (32), and an acrylic polymer dispersant: 【Chemical 1】 (wherein n1 represents an integer of 0 or 1, and X １ represents hydrochloric acid, amidosulfuric acid, or acetic acid, and n represents a natural number. The mass average molecular weight is in the range of 500 to 200,000. 【Chemistry 2】 (In the formula, n2a and n2b each independently represent an integer of 0 or 1, and X ２ａ and X ２ｂ each independently represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. The mass average molecular weight is in the range of 500 to 200,000. 【Chemistry 3】 (In the formula, n3a and n3b ​​each independently represent an integer of 0 or 1, and X ３ａ and X ３ｂ each independently represents hydrochloric acid, amidosulfuric acid, or acetic acid, and m and n each independently represent a natural number. The mass average molecular weight is in the range of 500 to 200,000. 【Chemistry 4】 (In the formula, R １ represents a hydrogen atom; n4 represents an integer of 0 or 1; X ４ represents hydrochloric acid, amidosulfuric acid, or acetic acid, and n represents a natural number. The mass average molecular weight is in the range of 500 to 200,000. 【Chemical 33】 (In the formula, R 4 represents a linear or branched alkyl group having 1 to 3 carbon atoms, a linear or branched alkoxy group having 1 to 3 carbon atoms, or an amino group, and m and n each independently represent a natural number.)

2. 2. The aqueous ink composition for a writing instrument according to claim 1, wherein n2a and n2b are integers of 0 or 1, or n3a and n3b ​​are integers of 0 or 1.

3. X ２ａ and X ２ｂ are the same, or X ３ａ and X ３ｂ 3. The water-based ink composition for a writing instrument according to claim 2, wherein

4. 4. The aqueous ink composition for a writing instrument according to claim 1, wherein the mass ratio of the cationic polymer to the acrylic polymer dispersant is 1:2.5 to 1:

16.

5. 5. The aqueous ink composition for a writing instrument according to claim 1, wherein the viscosity of the composition is 1 to 20 mPa·s at 20° C. and at a rotation speed of 30 rpm using a BL-type rotational viscometer.

6. 6. The aqueous ink composition for a writing instrument according to claim 1, wherein the reversible thermochromic microencapsulated pigment has an average particle size in the range of 0.01 to 5 μm.

7. An aqueous ink composition for a writing instrument as described in any one of claims 1 to 6, wherein the component (c) is in the range of 60 to 90 mass% of the total amount of the reversible thermochromic composition, the mass average molecular weight is 250 or more, and the specific gravity of the reversible thermochromic microencapsulated pigment in a fully colored state at 20°C when water is used as a reference substance is 1.05 to 1.

20.

8. An aqueous ink composition for a writing instrument described in any one of claims 1 to 7, wherein the acrylic polymer dispersant is a comb-type polymer dispersant having a carboxy group in the side chain.

9. An aqueous ink composition for a writing instrument described in any one of claims 1 to 8, wherein the vehicle contains a specific gravity adjuster consisting of an oxyacid of a Group 6 element having an atomic weight of 90 to 185 or a salt thereof.

10. A writing instrument containing an aqueous ink composition for a writing instrument described in any one of claims 1 to 9.

11. A writing instrument as described in Claim 10, which is provided with a marking pen tip made of a resin-processed body or a resin-molded body having capillary gaps formed therein.

12. A writing instrument as described in Claim 11, which is a marking pen having an ink absorbing body made of a fiber bundle built into the barrel of the writing instrument, and the ink absorbing body and the marking pen tip connected together, and the ink absorbing body is impregnated with the water-based ink composition for the writing instrument.

13. A writing instrument as described in any one of claims 10 to 12, comprising a friction member that discolors writing made with the writing instrument due to frictional heat.

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