Oil-based ink composition for writing instrument and writing instrument containing the same

Abstract

To provide an oil-based ink composition for a writing instrument, and a writing instrument, which can maintain a clear and highly visible handwriting over a long period of time without the handwriting becoming faint due to color fading even after repeated washing, when writing is performed on a fibrous substrate, such as a fabric or tag, that is expected to be subjected to washing.SOLUTION: Provided are an oil-based ink composition for a writing instrument comprising a colorant, an organic solvent, and a phenol compound represented by a general formula described in the specification, where the phenol compound has a melting point in the range from 70°C to 250°C and is contained in an amount of more than 5 mass% based on the total mass of the ink composition; and a writing instrument.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to an oil-based ink composition for a writing instrument, and more particularly to an oil-based ink composition for a writing instrument that provides writing marks that have excellent washability when written on textile products, and a writing instrument incorporating the same. [Background technology]

[0002] Traditionally, marking pens with built-in oil-based ink, often called name pens, are used by children and others to mark their belongings, and are composed of ink compositions intended for writing on a variety of substrates, including resin moldings, films, and fabrics. In particular, handwriting on textiles such as fabrics and tags can become unrecognizable after repeated washing due to color fading and bleeding, so there is a demand for ink that is washable (washability). In order to solve the above problems, the application of various resins has been considered, and for example, a technique of adding a polyurethane resin made of an alcohol-soluble one-component polyurethane polyol has been disclosed (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-206669 Summary of the Invention [Problem to be solved by the invention]

[0004] The technology in Patent Document 1 involves dissolving a polymerized alcohol-soluble one-component polyurethane polyol together with a colorant in an organic solvent to form an ink, which allows handwriting on fibers such as fabric to form a strong resin film upon drying and adhere to the surface of the fibers, thereby preventing color fading during washing. However, because the polyurethane resin reacts with water and hardens during washing, repeated washing and drying can make the resin film brittle, causing the handwriting to crumble and peel off, leaving behind fine residue, or even easily peeling off depending on the type of fiber.

[0005] The present invention provides an oil-based ink composition for a writing instrument that can be used to write on any substrate, and that, after writing on a fibrous substrate (fabric, textile products such as fabrics and tags) that are expected to be washed, does not fade due to color fading even after repeated washing, and can maintain clear handwriting with excellent visibility for a long period of time, and a writing instrument. [Means for solving the problem]

[0006] The oil-based ink composition for a writing instrument of the present invention comprises a colorant, an organic solvent, and a phenolic compound represented by the following general formula (1) or (2), wherein the phenolic compound has a melting point in the range of 70 to 250°C and is blended in an amount exceeding 5% by mass of the total amount of the ink composition. [ka] [In the formula, R 1 , R 4 each independently represents a hydrogen atom, a methyl group, or a t-butyl group; R 2 , R 3 each independently represents a hydrogen atom or a methyl group. X is -CH2-, -CO-, -O-, or -NR 5 -, a divalent organic group selected from alicyclic hydrocarbons, or a divalent organic group consisting of a combination of two or more groups selected from these groups, and R 5 represents a hydrogen atom or an alkyl group. Y represents a carbon atom, a sulfur atom, a hydrocarbon group, an aromatic group, or a heterocycle. n represents an integer of 1 to 4. Further requirements are that the composition contains a phenolic resin, that the ratio of the phenolic resin to the phenolic compound is in the range of 1:5 to 5:1, and that the phenolic compound is a spiro compound having 2,4,8,10-tetraoxaspiro[5.5]undecane. Further, it is a requirement that the colorant is a dye, and that the dye is a metal-containing dye or a nigrosine dye. A further feature is a writing instrument incorporating any of the oil-based ink compositions for writing instruments described above. [Effects of the Invention]

[0007] The present invention provides an oil-based ink composition for a writing instrument and a writing instrument that can form clear handwriting on fibrous substrates such as fabrics and tags, even when applied to an oil-based writing instrument called a name pen, which is required to have good handwriting retention on various substrates, and that can maintain excellent visibility for a long period of time without causing the formed handwriting to fade or fade even after repeated washing. DETAILED DESCRIPTION OF THE INVENTION

[0008] The oil-based ink composition of the present invention has a melting point in the range of 70 to 250°C, and by incorporating a phenolic compound represented by the above general formula (1) or (2) in an amount exceeding 5 mass% based on the total amount of the ink composition, the ink composition has excellent washability, and the handwriting formed does not fade or fade even when a textile product on which a name or other inscription is written with the ink is repeatedly washed.

[0009] It is known that phenolic compounds represented by the general formula (1) or (2) function as antioxidants in small amounts. However, we have found that adding more than 5% by mass to an oil-based ink inhibits the ink from penetrating and spreading into the fibers when written on a fiber substrate, while firmly fixing the colorant to the fiber surface. This allows for the formation of handwriting that is highly visible and has minimal bleeding. Therefore, we believe that the formed handwriting is in a state where the fiber substrate and the colorant are solidified, thereby inhibiting peeling due to abrasion during washing or dissolution in detergent or water. Furthermore, it is thought that the speed at which the handwriting coating film is formed during writing is increased, which prevents the handwriting from bleeding even on substrates with high ink permeability, such as fibers, resulting in clear handwriting and making the handwriting appear darker.

[0010] Of the phenol compounds represented by the general formula (1) or (2), those with a melting point lower than 70°C tend to soften or dissolve when hot water is used during washing, making it difficult to obtain the desired fixability, while those with a melting point higher than 250°C tend to have low solubility in oil-based media and are prone to precipitation. Therefore, those with a melting point in the range of 70 to 250°C are used, preferably 75 to 205°C, and particularly preferably 78 to 125°C.

[0011] In the phenol compound represented by the general formula (1) or (2), R 1 and R 4 each independently represents a hydrogen atom, a methyl group, or a t-butyl group; R 2 and R 3 each independently represents a hydrogen atom or a methyl group. X is -CH2-, -CO-, -O-, or -NR 5 -, a divalent organic group selected from cycloalkanes, cycloalkenes, and alicyclic hydrocarbons formed from a combination thereof, or a divalent organic group formed from a combination of two or more groups selected from these groups, and R 5 represents a hydrogen atom or an alkyl group. Y represents a carbon atom, a sulfur atom, a hydrocarbon group having a straight chain or a branched chain, an aromatic group such as an aromatic hydrocarbon or a phenol, or a heterocycle consisting of a heterocyclic compound. n represents an integer of 1 to 4, and those having a plurality of phenol groups are particularly preferred because they tend to provide good washing resistance.

[0012] As the phenol compound used in the present invention, commercially available products may be used, for example, Sumilizer GA-80 (melting point 115°C), Sumilizer MDP-S (melting point 126°C), Sumilizer WX-R (melting point 160°C), Sumilizer WX-RC (melting point 160°C), Sumilizer BBM-S (melting point 209°C to 213°C), manufactured by Sumitomo Chemical Co., Ltd. BASF's Irganox 1035 (melting point 78°C), Irganox 1035FF (melting point 78°C), Irganox 245 (melting point 79°C), Irganox 245FF (melting point 79°C), Irganox 259 (melting point 104°C to 108°C), Irganox 1010 (melting point 120°C to 125°C), Irganox 1010FF (melting point 120°C to 125°C), Irganox 1098 (melting point 156°C to 161°C), Irganox 3114 (melting point 221°C), Irganox MD 1024 (melting point 227°C), Irganox 1330 (melting point 244°C), Kawaguchi Chemical Industry Co., Ltd.'s Antage Crystal (melting point 160°C) and Antage W-300 (melting point 209°C to 213°C), ADEKA Corporation's ADK STAB AO-80 (melting point 115°C), ADK STAB AO-60 (melting point 120°C to 125°C), ADK STAB AO-60G (melting point 120°C to 125°C), ADK STAB AO-30 (melting point 184°C), ADK STAB AO-40 (melting point 209°C to 213°C), ADK STAB AO-20 (melting point 221°C), ADK STAB AO-330 (melting point 244°C), Shipro Chemical Co., Ltd.'s Seenox BCS (melting point 160°C), Seenox 326M (melting point 244°C), Nocrac PBK (melting point 105° C.), Nocrac 300 (melting point 160° C.), Nocrac NS-30 (melting point 209 to 213° C.), etc., manufactured by Ouchi Shinko Chemical Industry Co., Ltd. can be used.

[0013] Among the compounds described above, spiro compounds in which Y in general formula (1) is a heterocycle and is 2,4,8,10-tetraoxaspiro[5.5]undecane are particularly useful because they exhibit excellent stability in ink and high washability. Specifically, 3,9-bis[2-{3-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}-1,1-dimethylethyl]-2,4,8,10-tetraoxaspiro[5.5]undecane, which is commercially available as Sumilizer GA-80 and Adeka Stab AO-80, is useful in terms of availability.

[0014] The phenol compound can impart the washing resistance that is an effect of the present invention by adding more than 5% by mass to the ink, and is added in the range of 5.05 to 30% by mass, preferably 5.1 to 25% by mass. If the amount is 5% by mass or less, it is difficult to obtain the desired effect, and although it is possible to add a large amount, if the amount is 30% by mass or less, the desired effect can be obtained sufficiently.

[0015] As the colorant, general-purpose dyes and pigments that have been conventionally used in oil-based inks can be used as appropriate. Examples of the dyes include organic solvent-soluble dyes that are classified as solvent dyes in the Color Index. Specific examples of the solvent dye include Varifast Black 3806 (CI Solvent Black 29), 3807 (trimethylbenzylammonium salt of CI Solvent Black 29 dye), Spirit Black SB (CI Solvent Black 5), Spiron Black GMH (CI Solvent Black 43), Varifast Red 1308 (a salt complex of CI Basic Red 1 dye and CI Acid Yellow 23 dye), Varifast Yellow AUM (a salt complex of CI Basic Yellow 2 dye and CI Acid Yellow 42 dye), and Spiron Yellow. Examples include C2GH (organic acid salt of CI Basic Yellow 2 dye), Spiron Violet CRH (CI Solvent Violet 8-1), Varifast Violet 1701 (a salt complex of CI Basic Violet 1 and CI Acid Yellow 42 dye), Spiron Red CGH (organic acid salt of CI Basic Red 1 dye), Spiron Pink BH (CI Solvent Red 82), Nigrosine Base EX (CI Solvent Black 7), Oil Blue 613 (CI Solvent Blue 5), and Neozapon Blue 808 (CI Solvent Blue 70). Examples of the pigment include inorganic pigments such as carbon black, ultramarine, and titanium dioxide pigments; organic pigments such as azo pigments, phthalocyanine pigments, indigo pigments, thioindigo pigments, threne pigments, quinacridone pigments, anthraquinone pigments, threne pigments, diketopyrrolopyrrole pigments, dioxazine pigments, perylene pigments, perinone pigments, and isoindolinone pigments; metal pigments obtained by treating the surface of aluminum powder or aluminum powder with a colored resin; metallic luster pigments obtained by forming a vapor-deposited film of metal such as aluminum on a transparent or colored transparent film; metal pigments having a thickness of 0.01 to 0.1 μm obtained by peeling off a vapor-deposited film of metal such as aluminum formed on a substrate such as a film; colloidal particles having an average particle size of 5 to 30 nm selected from gold, silver, platinum, and copper; fluorescent pigments, phosphorescent pigments, thermochromic pigments; and pearl pigments having a core material such as natural mica, synthetic mica, glass flakes, alumina, or a transparent film flakes coated with a metal oxide such as titanium oxide. The colorants may be used alone or in combination of two or more, and are used in an amount of 1 to 25% by mass in the ink composition.

[0016] The configuration of the present invention is particularly effective for dyes, which tend to bleed when written on fabrics compared to pigments and are also more likely to bleed into water and detergent during washing. Of the dyes mentioned above, metal-containing dyes and nigrosine dyes are particularly prone to dissociation during washing, making the configuration of the present invention particularly effective.

[0017] The organic solvent is not particularly limited, and any general-purpose solvent can be used. The ink composition may contain two or more organic solvents. Specific examples include benzyl alcohol, ethylene glycol, diethylene glycol, propylene glycol, benzyl glycol, ethylene glycol monobutyl ether, ethylene glycol monohexyl ether, ethylene glycol monophenyl ether, diethylene glycol monoethyl ether, diethylene glycol monophenyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monophenyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monophenyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monophenyl ether, methyl lactate, ethyl lactate, and γ-butyrolactone.

[0018] The organic solvent preferably contains, as a main organic solvent, an organic solvent having a vapor pressure at 20° C. of 5.0 to 50 mmHg, preferably 10 to 50 mmHg, in an amount of 50 mass % or more relative to the total mass. Such organic solvents are particularly preferred when the writing instrument containing the ink composition is a marking pen. The use of an organic solvent having such a vapor pressure can improve the drying properties of handwriting, thereby enabling the formation of good handwriting without problems such as undried ink adhering to the hand when the handwriting is touched or staining of blank areas on the writing surface where no handwriting has been formed.

[0019] Organic solvents with a vapor pressure of 5.0 to 50 mmHg at 20°C include alcohol-based organic solvents such as ethyl alcohol (45), n-propyl alcohol (14.5), isopropyl alcohol (32.4), n-butyl alcohol (5.5), isobutyl alcohol (8.9), sec-butyl alcohol (12.7), tert-butyl alcohol (30.6), and tert-amyl alcohol (13.0); glycol ether-based organic solvents such as ethylene glycol monomethyl ether (8.5), ethylene glycol diethyl ether (9.7), ethylene glycol monoisopropyl ether (6.0), propylene glycol monomethyl ether (7.6), and propylene glycol monoethyl ether (10.6); n-heptane (35.0), n-octane (11.0), isooctane (41.0), methylcyclohexane (37.0), and ethyl cyclohexane (10.6); Examples of suitable organic solvents include hydrocarbon organic solvents such as cyclohexane (10.0), toluene (24.0), xylene (5.0-6.0), and ethylbenzene (7.1); ketone organic solvents such as methyl isobutyl ketone (16.0), methyl n-propyl ketone (12.0), methyl n-butyl ketone (12.0), and di-n-propyl ketone (5.2); and ester organic solvents such as n-butyl formate (22.0), isobutyl formate (33.0), n-propyl acetate (25.0), isopropyl acetate (48.0), n-butyl acetate (8.4), isobutyl acetate (13.0), ethyl propionate (28.0), n-butyl propionate (45.0), methyl butyrate (25.0), and ethyl butyrate (11.0). The numbers in parentheses indicate the vapor pressure (mmHg) of each organic solvent at 20°C.

[0020] Among the organic solvents described above, from the viewpoints of quick-drying of handwriting and solubility of usable resins and additives, alcohol-based organic solvents having 4 or less carbon atoms and / or glycol ether-based organic solvents having 4 or less carbon atoms are preferred, and specifically, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, ethylene glycol monomethyl ether, ethylene glycol diethyl ether, ethylene glycol monoisopropyl ether, propylene glycol monomethyl ether, and propylene glycol monoethyl ether are preferred.

[0021] Furthermore, a high-boiling organic solvent having a boiling point of 160 to 250°C is preferably used as a main solvent when the writing instrument containing the ink composition is a ballpoint pen, but it is also useful to include it as an auxiliary solvent in an ink composition contained in a marking pen, etc. This makes it possible to adjust the drying speed of the handwriting and suppress whitening of the handwriting, which is likely to occur in a humid environment. In particular, when an organic solvent having a vapor pressure of 5.0 to 50 mmHg at 20°C, such as an alcohol-based solvent having 3 or less carbon atoms and / or a glycol ether-based solvent having 4 or less carbon atoms, is used as the main solvent, it is preferable to use a high-boiling organic solvent in combination to adjust the drying speed.

[0022] High boiling point organic solvents include benzyl alcohol (205), ethylene glycol monophenyl ether (245), propylene glycol-n-butyl ether (170), dipropylene glycol methyl ether (190), propylene glycol diacetate (190), dipropylene glycol dimethyl ether (175), dipropylene glycol-n-propyl ether (212), dipropylene glycol methyl ether acetate (209), propylene glycol phenyl ether (216), and propylene glycol methyl ether acetate (217). nyl ether (243), tripropylene glycol methyl ether (242), dipropylene glycol-n-butyl ether (229), tripropylene glycol-n-butyl ether (274), p-xylene glycol dimethyl ether (235), benzyl formate (201), benzyl acetate (212), benzyl propionate (222), benzyl butyrate (240), benzyl isobutyrate (230), 3-methoxy-N,N-dimethylpropanamide (215), and the like. The numbers in parentheses indicate the boiling points (in degrees Celsius) of the respective organic solvents.

[0023] The content of the organic solvent in the ink composition of the present invention is preferably 40 to 80 mass % based on the total mass of the ink composition. When the organic solvent having a vapor pressure of 5.0 to 50 mmHg at 20°C is used, the content is preferably 50% by mass or more, and more preferably 70% by mass or more, relative to the total mass of the organic solvents. When the high-boiling organic solvent is used as a co-solvent, the content is preferably 1 to 25% by mass, and more preferably 2 to 13% by mass, relative to the total mass of the organic solvents.

[0024] Furthermore, it is preferable to add a resin to the ink for the purpose of inhibiting bleeding of handwriting, improving fixation, and imparting durability, etc., and any resin that is soluble in the organic solvent can be used without any particular limitation. Specific examples include ketone resins, amide resins, alkyd resins, rosin-modified resins, rosin-modified phenolic resins, phenolic resins, xylene resins, polyvinyl butyral resins, terpene resins, coumarone-indene resins, polyvinylpyrrolidone, polyethylene oxide, polymethacrylic acid esters, ketone-formaldehyde resins, α- and β-pinene-phenol polycondensation resins, polyvinyl butyral resins, acrylic resins, and polyacrylic acid-polymethacrylic acid copolymers. These resins may be used alone or in combination of two or more, in an amount of 0.5 to 40% by mass, preferably 1 to 20% by mass, of the ink composition. If the amount is less than 0.5% by mass, sufficient effects such as suppressing bleeding of handwriting onto the substrate, improving fixation, and imparting fastness cannot be achieved, while if added in an amount exceeding 40% by mass, the solubility of the resin in the solvent may decrease, resulting in a decrease in the fluidity of the ink.

[0025] In particular, since phenolic resins have a phenol group like the above-mentioned phenolic compounds, they are compatible with each other, and their use in combination with the phenolic compounds can further improve the suppression of bleeding of handwriting, washing resistance, and ink stability, making this a suitable combination for writing on synthetic fibers such as polyester and nylon, which are fiber substrates that tend to bleed and remove handwriting easily by washing.

[0026] When a phenolic resin is used, the ratio of the phenolic resin to the above-mentioned phenolic compound is preferably in the range of 1:5 to 5:1, that is, the amount is preferably 5 times or less relative to either material. The above ratio is more preferable because it provides particularly high suppression of bleeding of handwriting, high wash resistance, and high ink stability.

[0027] In addition to the above components, various additives such as antioxidants, ultraviolet absorbers, rust inhibitors, lubricants, viscosity modifiers, release agents, pigment dispersants, antifoaming agents, shear thinning agents, surfactants, etc. may be used as needed. The additives are so-called conventional additives, and may be selected from known compounds and used as needed.

[0028] For example, the rust inhibitor may be benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin, or the like. As the antioxidant, dibutylhydroxytoluene, nordihydroxytoluene, flavonoids, butylhydroxyanisole, ascorbic acid derivatives, α-tocopherol, catechins, etc. can be used. Examples of ultraviolet absorbers that can be used include 2-(2'-hydroxy-3'-t-butyl-5'-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, and p-benzoic acid-2-hydroxybenzophenone. As the antifoaming agent, dimethylpolysiloxane or the like can be used.

[0029] Furthermore, when the oil-based ink composition of the present invention is applied to a ballpoint pen, a lubricant such as a higher fatty acid such as oleic acid, a nonionic surfactant having a long-chain alkyl group, a polyether-modified silicone oil, or a thiophosphite triester such as thiophosphite tri(alkoxycarbonylmethyl ester) or thiophosphite tri(alkoxycarbonylethyl ester) can be added as needed. In particular, the use of a phosphate monoester of a polyoxyethylene alkyl ether or a polyoxyethylene alkylaryl ether, a phosphate diester of a polyoxyethylene alkyl ether or a polyoxyethylene alkylaryl ether, or a metal salt, ammonium salt, amine salt, or alkanolamine salt thereof, provides an excellent effect in preventing wear of the ball seat.

[0030] Furthermore, the addition of a shear thinning agent can prevent ink from leaking from the gap between the ball and tip when not in use, and can prevent ink from flowing back when the writing tip is left facing upward (upright). Furthermore, writing with ink that incorporates a shear thinning agent becomes highly viscous immediately after writing, making it excellent for writing on fibrous substrates where ink tends to bleed, and it is easy to obtain clear handwriting without bleed. The shear thinning agent can be a conventionally known compound, and examples thereof include crosslinked acrylic resins, emulsion-type crosslinked acrylic resins, crosslinked N-vinylcarboxylic acid amide polymers or copolymers, non-crosslinked N-vinylcarboxylic acid amide polymers or copolymers, aqueous solutions of non-crosslinked N-vinylcarboxylic acid amide polymers or copolymers, hydrogenated castor oil, waxes such as fatty acid amide wax and oxidized polyethylene wax, fatty acid metal salts such as aluminum stearate, aluminum palmitate, aluminum octoate and aluminum laurate, dibenzylidene sorbitol, dextrin fatty acid esters, N-acylamino acid compounds, smectite-based inorganic compounds, montmorillonite-based inorganic compounds, bentonite-based inorganic compounds, hectorite-based inorganic compounds, and silica.

[0031] The oil-based ink composition of the present invention is used in practice by being filled into a ballpoint pen or marking pen having a tip attached to the writing tip. When filling a ballpoint pen, the structure and shape of the ballpoint pen itself are not particularly limited, and examples include a structure in which ink is impregnated into an ink absorbing body made of a fiber bundle housed inside the barrel and ink is supplied to the writing tip; a structure in which ink is housed directly inside the barrel with a comb-shaped ink flow rate adjusting member or an ink flow rate adjusting member made of a fiber bundle interposed therebetween; and a ballpoint pen having an ink reservoir tube filled with the ink composition inside the barrel, the ink reservoir tube communicating with a tip having a ball attached to the tip, and further having an ink follower such as a liquid stopper or solid stopper in close contact with the end face of the ink to prevent backflow. When filling a marking pen, the structure and shape of the marking pen itself are not particularly limited, and examples include a structure in which a fiber tip, felt tip, plastic tip, or metal tip is attached to the writing tip, and ink is impregnated into an ink occlusion body made of a fiber bundle housed inside the barrel, and ink is supplied to the writing tip; a structure in which ink is directly housed inside the barrel and an ink flow rate regulator member in the shape of a comb groove or made of a fiber bundle is interposed; and a structure in which ink is directly housed inside the barrel and a predetermined amount of ink is supplied to the writing tip by a valve mechanism.Furthermore, marking pens can also be of the ink cartridge type or ink refill type. In particular, when a polyester tip, which is a resin-processed polyester fiber bundle, is used as the tip applied to the marking pen, the writing feel is soft and handwriting can be made without getting caught on fibers such as fabric, and handwriting can be made with a uniform amount of ink without causing bleeding, etc., so the effects of the ink of the present invention are easily and effectively manifested. [Example]

[0032] The ink compositions of the examples and comparative examples are shown in Tables 1 and 2 below. The numerical values ​​of the compositions in the table indicate parts by mass.

[0033] [Table 1]

[0034] The contents of the ingredients in Table 1 are explained according to the note numbers. (1) Orient Chemical Industry Co., Ltd., product name: Nigrosine Base EX (2) Orient Chemical Industry Co., Ltd., product name: Varifast Red 1308 (3) Orient Chemical Industry Co., Ltd., product name: Oil Blue 613 (4) NSP-BT 8733X (pigment content 10%), manufactured by Nikko Bix Co., Ltd. (5) Yasuhara Chemical Co., Ltd., product name: YS Polyster G150 (6) Sumitomo Chemical Co., Ltd., product name: Sumilizer GA-80 (melting point 115°C) (7) BASF, trade name: Irganox 1035 (melting point 78°C) (8) Nocrac PBK (melting point 105°C), manufactured by Ouchi Shinko Chemical Industry Co., Ltd. (9) ADEKA Corporation, product name: ADK STAB AO-50 (melting point: 53°C) (10) Ouchi Shinko Chemical Industry Co., Ltd., product name: Nocrac DAH (melting point 170°C), 2,5-Di-tert-amylhydroquinone (11) Taoka Chemical Co., Ltd., product name: TBIS-RX (melting point: 270°C) (12) Daihachi Chemical Industry Co., Ltd., product name: AP-10

[0035] Preparation of oil-based ink composition for marking pen The raw materials were mixed in the amounts shown in Table 1 above, and the mixture was stirred at 20° C. for 3 hours to dissolve the raw materials, thereby obtaining an ink composition.

[0036] Making a marking pen 1.5 g of each ink composition of the Examples and Comparative Examples in Table 1 was placed in a commercially available marking pen exterior (MFN-15N, manufactured by Pilot Corporation, equipped with a polyester tip) to obtain an oil-based marking pen.

[0037] [Table 2]

[0038] The contents of the ingredients in Table 2 are explained according to the note numbers. (13) Orient Chemical Industry Co., Ltd., product name: Varifast Violet 1705 (14) Orient Chemical Industry Co., Ltd., trade name: Varifast Red 1308 (15) Fuji Pigment Co., Ltd., product name: FUJI ABL BLACK 8197 (pigment content 10%) (16) Sekisui Chemical Co., Ltd., product name: S-LEC BL-1 (17) Yasuhara Chemical Co., Ltd., product name: YS Polyster G150 (18) ADEKA Corporation, product name: ADK STAB AO-80 (melting point 115°C) (19) BASF, trade name: Irganox 1035F (melting point: 78°C) (20) BASF, trade name: Irganox MD 1024 (melting point: 227°C) (21) Kawaguchi Chemical Industry Co., Ltd., trade name: ANTAGE HP-500 (melting point 28°C), 2,4-Bis(dodecylthiomethyl)-6-methyl phenol (22) 4,4'-Dihydroxydiphenyl Sulfone, manufactured by Nicca Chemical Industry Co., Ltd., trade name: BP-S / FF-1 (melting point: 247°C). (23) Mitsui Chemicals, Inc., product name: Takelac W-6061 (solid content 30%) (24) Nippon Shokubai Co., Ltd., product name: PVP K85N (25) Daiichi Kogyo Seiyaku Co., Ltd., trade name: Plysurf A208N

[0039] Preparation of oil-based ink composition for ballpoint pens The raw materials were mixed in the amounts shown in Table 2 above, heated to 60°C, completely dissolved using a disper stirrer, and allowed to cool at room temperature to obtain an ink composition.

[0040] Making a ballpoint pen A ballpoint pen was obtained by placing 0.2 g of each ink composition of the Examples and Comparative Examples in Table 2 into a commercially available ballpoint pen exterior (manufactured by Pilot Corporation: BSGC-10F) equipped with a ball with a ball diameter of 0.7 mm.

[0041] Written and washing tests Using each of the resulting writing implements, writing was performed on 100% cotton fabric and 100% polyester satin fabric, and bleeding during writing and washing resistance after a washing test were evaluated. The evaluation results are shown in Tables 3 and 4 below. [Bleeding] After writing the word "Pilot," the state of the writing on each fiber substrate was visually evaluated. No bleeding observed: ○ Slight bleeding occurs: △ Smearing: × [Washing resistance] The fiber substrates for which the bleeding properties of the handwriting had been confirmed were used and washed for 1 hour in a household washing machine using 15 g of household laundry detergent (Miyoshi Soap Powder, manufactured by Miyoshi Soap Co., Ltd.) per 3 liters of water at 50°C. After air drying at room temperature, the condition of the handwriting was evaluated visually. The handwriting remains the same as before washing:◎ The degree to which handwriting becomes slightly faint: Yes Handwriting becomes slightly faint: △ The handwriting becomes very faint or unreadable: ×

[0042] [Table 3] [Table 4]

Claims

1. An oil-based ink composition for a writing instrument, comprising a colorant, an organic solvent, and a phenolic compound represented by the following general formula (1) or (2), wherein the phenolic compound has a melting point in the range of 70 to 250°C and is blended in an amount exceeding 5 mass% of the total amount of the ink composition: 【Chemical 1】 [In the formula, R １ , R ４ each independently represents a hydrogen atom, a methyl group, or a t-butyl group; R ２ , R ３ each independently represents a hydrogen atom or a methyl group. X is -CH ２ -, -CO-, -O-, -NR ５ -, a divalent organic group selected from alicyclic hydrocarbons, or a divalent organic group consisting of a combination of two or more groups selected from these groups; R ５ represents a hydrogen atom or an alkyl group. Y represents a carbon atom, a sulfur atom, a hydrocarbon group, an aromatic group, or a heterocycle. n represents an integer of 1 to 4.

2. 2. The oil-based ink composition for a writing instrument according to claim 1, which contains a phenolic resin.

3. 3. The oil-based ink composition for writing instruments according to claim 2, wherein the ratio of the phenolic resin to the phenolic compound is in the range of 1:5 to 5:

1.

4. 4. The oil-based ink composition for a writing instrument according to claim 1, wherein the phenol compound is a spiro compound having 2,4,8,10-tetraoxaspiro[5.5]undecane.

5. 2. The oil-based ink composition for a writing instrument according to claim 1, wherein the colorant is a dye.

6. 6. The oil-based ink composition for a writing instrument according to claim 5, wherein the dye is a metal-containing dye or a nigrosine dye.

7. A writing instrument incorporating the oil-based ink composition for writing instruments according to any one of claims 1 to 6.

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