Oil-based ink composition for writing instruments, water-based ink composition for writing instruments, and ballpoint pen

Abstract

To provide an ink composition for writing instruments having excellent dispersibility of a coloration component, and a ballpoint that includes such an ink composition for writing instruments and has excellent writing feel and high handwriting fastness.SOLUTION: The foregoing problem is solved by an ink composition for writing instruments containing a compound having a specific structure.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an oil-based ink composition for writing instruments, an aqueous ink composition for writing instruments, and a ballpoint pen.

Background Art

[0002] In recent years, in writing instruments (especially ballpoint pens), the demand for user requirements such as writing feel, writing start (initial writing performance), and stable continuation of handwriting due to differences in ink and functions has been rapidly increasing. Ballpoint pens are roughly classified into oil-based ballpoint pens, water-based ballpoint pens, gel ink ballpoint pens, etc.

[0003] Oil-based ink has various colors such as black, red, blue, pink, green, orange, etc., and is usually produced by dissolving or dispersing a colorant in an organic solvent. Further, in order to improve writing performance, resins, surfactants, additives, etc. are added according to the application.

[0004] As the colorant contained in the oil-based ink, dyes, pigments, and mixtures thereof are used. For example, oil-based ink using a pigment is excellent in the fastness of handwriting, but the pigment is likely to aggregate and precipitate in the ink, and there may be problems in the handwriting. On the other hand, oil-based ink using a dye has a characteristic that the dye is easily dissolved in a solvent, so it is less likely to aggregate and precipitate compared to a pigment, but the water resistance and weather resistance tend to be inferior.

[0005] Also, as dyes, various dyes such as acid dyes and basic dyes, and processed type dyes such as salt-forming dyes are known. For example, inks using methine dyes as colorants (Patent Document 1) and inks using mixtures of dyes and pigments (Patent Document 2) have been reported.

[0006] On the other hand, in addition to water-soluble dyes, water-based ink uses pigments and oil-based dyes dispersed therein as colorants.

[0007] In recent years, cellulose nanofibers, which can be obtained by chemically or mechanically defibrating plant fibers, have attracted attention, and utilization research is actively conducted in various fields. And examples of utilizing cellulose nanofibers for writing instrument applications have been reported (Patent Documents 3 to 4). In addition, methods of emulsion polymerizing monomers to encapsulate colorants have been reported (Patent Documents 5 to 6).

Prior Art Documents

Patent Documents

[0008]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Summary of the Invention

Problems to be Solved by the Invention

[0009] The dyes described in Patent Documents 1 and 2 are likely to aggregate as dyes. When the solvent of the ink at the tip of the ball tip evaporates, the ink thickens, and a bleeding phenomenon may occur during writing. In addition, depending on the usage environment, there is a problem that good writing quality (the handwriting density remains unchanged and the handwriting continues to appear stably) cannot be obtained and the handwriting fastness is low.

[0010] In addition, when using a dye, there is a problem that the compatibility with a carrier (resin or cellulose nanofiber) causes aggregation of the dye and the carrier respectively, and the carrier is not uniformly dyed by the dye. Further, an ink composition containing such a carrier in a non-uniform dyeing state has a problem of poor storage stability.

Means for Solving the Problems

[0011] The present invention relates to an oil-based ink composition for writing instruments containing a medium containing alcohol or glycol ether, a resin present in a dissolved state in the medium, and a colorant containing a compound represented by the following general formula (1). It relates to an oil-based ink composition for writing instruments containing the same.

[0012]

Chemical Formula

[0013] [R 1 ~R 2 each independently represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms or a cyclic alkyl group having 3 to 12 carbon atoms, R 3 represents a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms, R 4 represents any functional group selected from the group consisting of a t-butyl group, an iso-propyl group, a phenyl group and a benzyl group.] Further, the present invention relates to an aqueous ink composition for writing instruments containing an aqueous medium and a carrier dispersed in the aqueous medium, wherein the carrier carries a compound represented by the above general formula (1). It relates to an aqueous ink composition for writing instruments characterized by this.

Advantages of the Invention

Advantages of the Invention

[0014] According to the present invention, it is possible to provide an oil-based ink composition for writing instruments in which aggregation of a colorant is suppressed even under low-temperature and high-temperature conditions.

[0015] Further, by using the above oil-based ink composition for writing instruments, it is possible to provide a ballpoint pen that suppresses the scratching phenomenon during writing, has a good writing feel in which skipping and scratching are less likely to occur in the handwriting, and has high handwriting fastness.

[0016] Also, according to the present invention, it is possible to provide an aqueous ink composition for writing instruments in which the dispersion stability of a carrier in an aqueous medium is high.

[0017] Furthermore, by using the above aqueous ink composition for writing instruments, it is possible to provide a ballpoint pen that suppresses the scratching phenomenon during writing, has a good writing feel in which skipping and scratching are less likely to occur in the handwriting, and has high handwriting fastness.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described in detail.

[0019] [Colorant] First, the compound represented by the general formula (1) used as a colorant will be described.

[0020]

Chemical formula

[0021] [R 1 ~R 2 each independently represents a linear alkyl group having 1 to 12 carbon atoms, a branched alkyl group having 3 to 12 carbon atoms, or a cyclic alkyl group having 3 to 12 carbon atoms, R 3 represents a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms, R 4represents any functional group selected from the group consisting of a t-butyl group, an iso-propyl group, a phenyl group, and a benzyl group. When the substituent at the 2-position of the [1,2,4]triazolo[1,5-a]pyridine ring has a branched structure such as a heptan-3-yl group (the following conventional dye X) as described in the prior art, due to steric interaction, repulsion occurs between the alkylamino group of the thiazole ring. It is considered that due to this repulsive effect, the overall structure spreads out greatly, and the molecules approach each other and are likely to aggregate by hydrogen bonding.

[0022]

Chemical formula

[0023] On the other hand, in the compound represented by the general formula (1), the substituent at the 2-position of the [1,2,4]triazolo[1,5-a]pyridine ring has a branched alkyl group, a phenyl group, or a benzyl group via one methylene group. Therefore, the steric interaction is alleviated by having one methylene group between the alkylamino group of the thiazole ring. As a result, the whole molecule becomes in a small state. Consequently, it is considered that other molecules are less likely to approach the nitrogen atom that promotes hydrogen bonding, and aggregation is suppressed.

[0024] That is, it is presumed that by using the compound represented by the general formula (1) as a colorant, aggregation of the colorant in the oil-based ink composition for writing instruments can be suppressed even under low-temperature and high-temperature conditions. Also, in the aqueous ink composition for writing instruments, the dispersion stability of the carrier carrying the general formula (1) in the aqueous medium is high.

[0025] [Compound represented by the general formula (1)] First, the compound represented by the general formula (1) will be described.

[0026]

Chemical formula

[0027] In general formula (1), R 1 ~R 2 The linear alkyl group having 1 to 12 carbon atoms, branched alkyl group having 3 to 12 carbon atoms, and cyclic alkyl group having 3 to 12 carbon atoms in are not particularly limited. For example, methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-undecyl group, n-dodecyl group, 2-ethylhexyl group, cyclohexyl group can be mentioned.

[0028] Among these, a branched alkyl group is preferable, and a 2-ethylhexyl group is more preferable. In particular, it is preferable that both R 1 and R 2 are 2-ethylhexyl groups.

[0029] In general formula (1), the linear alkyl group having 1 to 4 carbon atoms in R 3 is not particularly limited. For example, methyl group, ethyl group, n-propyl group, n-butyl group, etc. can be mentioned. Further, examples of the branched alkyl group having 3 to 4 carbon atoms include iso-propyl group, sec-butyl group, tert-butyl group, etc. Among these, a methyl group, an ethyl group, or an n-butyl group is preferable, and a methyl group is particularly most effective.

[0030] In general formula (1), R 4 represents any functional group selected from the group consisting of t-butyl group, iso-propyl group, phenyl group, and benzyl group. Among these, a t-butyl group or a phenyl group is preferable.

[0031] The compound represented by general formula (1) can be synthesized with reference to the known method described in Patent Document (Japanese Patent Laid-Open No. 08-245896).

[0032] Examples of preferred compounds of the compound of the present invention represented by the general formula (1) are shown in the following (1-1) to (1-15), but the present invention is not limited thereto.

[0033]

Chemical formula

[0034] The compound represented by the above general formula (1) may be used alone, or two or more thereof may be used in combination in order to adjust the color tone or the like according to the application.

[0035] Among these compounds, (1-1), (1-2), (1-4), (1-5), (1-6), (1-8), (1-10), (1-12), (1-14) are preferred. In particular, when R 1 and R 2 are 2-ethylhexyl groups and R 3 is a methyl group, the effects of the present invention are particularly remarkable when (1-2), (1-4), (1-5), (1-6) are used.

[0036] The compounding amount of the compound represented by the general formula (1) is appropriately selected according to the application, but it is preferably 1 to 50% by mass based on the total amount of the ink composition. More preferably, it is 2 to 45% by mass, and still more preferably, it is 5 to 40% by mass.

[0037] Further, only the compound represented by the general formula (1) may be used as a colorant, or other known colorants may be used in combination.

[0038] The colorants (dyes, pigments) that can be used in combination are determined according to the purpose and application of the ink in consideration of the hue, printing sensitivity, light resistance, storage stability, solubility with the resin, and the like.

[0039] Known dyes that can be used in combination are not particularly limited. For example, acid dyes, basic dyes, metal complex dyes, salt-forming dyes, azine dyes, condensed azo compounds, azo metal complexes, diketopyrrolopyrrole compounds, anthraquinone compounds, quinacridone compounds, naphthol compounds, benzimidazolone compounds, thioindigo compounds, perylene compounds, methine compounds, allylamide compounds, phthalocyanine dyes, triphenylmethane dyes, basic dye lake compounds, oxazine compounds, thiazine compounds, xanthene compounds, etc. can be mentioned.

[0040] Specific examples include NIGROSIN BASE EX-BP, NUBIAN BLACK PA-2800, VALIFAST BLACK 1805, VALIFAST BLACK 1807, VALIFAST BLACK 1815, VALIFAST BLACK 1821, Oil Blue 613, VALIFAST RED 1308, VALIFAST RED 1320, VALIFAST RED 1355, VALIFAST RED 1360, VALIFAST BLUE 1601, VALIFAST BLUE 1605, VALIFAST BLUE 1621, VALIFAST YELLOW 1101, VALIFAST YELLOW 1151 (manufactured by Orient Chemical Industries, Ltd.), Aizen Spilon Blue 2BNH, Aizen Spilon Red C-GH, Aizen Spilon Red C-BH, Aizen Spilon Yellow C-GHN new, Aizen Spilon Yellow GRLH special, Aizen S.P.T. Blue-121 (manufactured by Hodogaya Chemical Co., Ltd.), etc. Known pigments that can be used in combination are not particularly limited. For example, carbon black, aniline black, titanium dioxide pigment, phthalocyanine, quinacridone, diketopyrrole, azo, dioxane, quinophthalone, triphenylmethane, perylene, perinone, metallic pigment, pearl pigment, fluorescent pigment, phosphorescent pigment, etc. can be mentioned. The pigment preferably has an average particle size of 30 nm to 700 nm after being dispersed in the medium.

[0041] Specific examples include, for example, FUJI FAST RED 8800 (C.I.Pigment Red 254), FUJI FAST RED 2200 (C.I.Pigment Red 170) (both manufactured by Fuji Pigment Co., Ltd.), and the like.

[0042] The blending amount of the pigment can be blended as needed in the range of 0.5 to 25% by mass, preferably 0.5 to 20% by mass, based on the total amount of the ink composition.

[0043] In addition, the colorant including the compound represented by the general formula (1) and the dyes and pigments that can be used in combination is appropriately selected according to the application, but it is preferably blended in the range of 1 to 50% by mass based on the total amount of the ink composition.

[0044] <Oil-based ink composition for writing instruments> Next, the oil-based ink composition for writing instruments according to the present invention will be described.

[0045] The oil-based ink composition for writing instruments contains, in addition to the colorant containing the compound represented by the general formula (1), a medium containing alcohol or glycol ether, and a resin present in a dissolved state in the medium.

[0046] In addition, additives may be appropriately added within a range that does not inhibit the characteristics in various applications, in addition to the above components. The additives will be described later.

[0047] [Medium] The "medium" in the present invention is alcohol or glycol ether. The medium is selected according to the purpose and application of the ink, is not particularly limited, and one kind or two or more kinds can be used.

[0048] Hereinafter, the alcohols preferably used will be described.

[0049] For example, alkyl monoalcohols without substituents such as ethanol, isopropanol, n-butanol, isobutanol, tert-butanol, sec-butanol, 2-methyl-2-butanol, 3-pentanol, octanol, cyclohexanol, etc.; alkyl monoalcohols with substituents such as 2-phenoxyethanol, 3-methyl-3-methoxy-1-butanol, etc.; alkyl polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, 3-methyl-1,3-butanediol, 1,3-butanediol, etc.; aromatic alcohols such as benzyl alcohol, etc. Substituents in the alkyl monoalcohol with substituents include an alkoxy group and an aryloxy group.

[0050] Furthermore, glycol ether-based alcohols such as ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, triethylene glycol monobutyl ether, etc. are included.

[0051] In particular, 3-methyl-3-methoxy-1-butanol, 1,3-butanediol, and propylene glycol monomethyl ether are preferably used.

[0052] Also, glycol ethers can also be preferably used. Among glycol ethers, there are also monoalcohol monoethers, but these have been described as alcohols. Hereinafter, diethers will be exemplified. Examples include ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol, ethylene glycol diethyl ether, diethylene glycol diethyl ether, diethylene glycol dipropyl ether, etc.

[0053] Also, in addition to alcohols and glycol ethers, the medium may contain water; ester solvents such as 3-methyl-3-methoxybutyl acetate, butyl acetate, methyl propionate, etc.

[0054] The amount of the medium varies depending on the type of writing instrument such as ballpoint pens, felt-tip pens, and marking pens. Based on the total amount of the ink composition, it is preferably 1 to 70% by mass, more preferably 3 to 60% by mass, and particularly preferably 5 to 30% by mass.

[0055] [Resin] The oil-based ink composition for writing instruments contains a resin present in a dissolved state in the above medium for adjusting the viscosity of the ink and improving the abrasion resistance.

[0056] The resin is determined according to the purpose and use of the ink and is not particularly limited. For example, butyral resin, ketone resin, polyvinylpyrrolidone resin, styrene resin, styrene-acrylic resin, styrene-maleic acid resin, terpene resin, acrylic resin, polyvinyl acetal resin, polyvinyl butyral resin, terpene phenol resin, rosin-modified maleic resin, rosin phenol resin, maleic acid resin, phenol resin, xylene resin, urea resin, polyamide resin, phenoxy resin, cellulose-based resin, etc. may be mentioned. These resins may be used alone or in combination of two or more as necessary.

[0057] In the present invention, butyral resin and ketone resin are preferably used in order to achieve a writing feeling without feathering.

[0058] Examples of the butyral resin include Esrec BL-1, BL-2, BL-10 of low polymerization degree type, BH-3, BH-6, BX-1, BX-5, BH-S (manufactured by Sekisui Chemical Co., Ltd.) of high polymerization type, etc.

[0059] Examples of the ketone resin include Ketone Resin K-90 (manufactured by Arakawa Chemical Industries, Ltd.), Hylac 901, Hylac 110H, Hylac 111 (manufactured by Hitachi Chemical Co., Ltd.), etc.

[0060] Examples of the polyvinylpyrrolidone resin include polyvinylpyrrolidone K-90 (manufactured by Nippon Shokubai Co., Ltd.).

[0061] The blending amount of the resin is preferably 1 to 50% by mass, more preferably 3 to 30% by mass, and particularly preferably 5 to 25% by mass based on the total amount of the ink composition. Within the above range, the viscosity can be easily adjusted, wear of the pen tip can be prevented, and a stable and good writing feel can be obtained. Furthermore, since the film-forming property can be moderately suppressed, even when the pen tip remains exposed, solidification of the ink can be suppressed, and the "scum phenomenon" during writing can be suppressed.

[0062] [Additives] Furthermore, additives may be added as long as they do not adversely affect the ink. Examples include rust inhibitors, surfactants, lubricants, wetting agents, ultraviolet absorbers, defoamers, antioxidants, pH adjusters, leveling agents, preservatives, cellulose nanofibers, and the like.

[0063] The rust inhibitor is not particularly limited, and examples include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin, ethylenediaminetetraacetic acid, metal salt-based compounds, and phosphate ester-based compounds.

[0064] The surfactant is not particularly limited, and examples include cationic surfactants, anionic surfactants, nonionic surfactants, amphoteric surfactants, silicone-based surfactants, and fluorine-based surfactants.

[0065] The lubricant is not particularly limited, and examples thereof include higher fatty acids, silicone oil, glycerin fatty acid esters, castor oil, phosphate esters and their metal salts, ammonium salts, etc., which have an effect of preventing wear of the ball seat of the ball tip of the ballpoint pen. These lubricants may be used alone or in combination of two or more. Further, in order to improve lubricity, fine particles such as silica fine particles and alumina fine particles may be added.

[0066] The wetting agent is not particularly limited, and examples thereof include glycerin, sorbitan-based compounds, polysaccharides, urea, etc.

[0067] The ultraviolet absorber is not particularly limited, and examples thereof include 2-(2'-hydroxy-3'-t-butyl 5'-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, and p-benzoic acid-2-hydroxybenzophenone.

[0068] The defoaming agent is not particularly limited, and examples thereof include silicone-based compounds such as dimethylpolysiloxane, mineral oil, and fluorine-based compounds.

[0069] The antioxidant is not particularly limited, and examples thereof include dibutylhydroxytoluene, nordihydroxytoluene, flavonoid, butylhydroxyanisole, ascorbic acid derivatives, α-tocopherol, catechins.

[0070] The pH adjuster is not particularly limited, and examples thereof include alkalis such as sodium hydroxide, alkanolamine, oxyethylene alkylamine, polyoxyethylene alkylamine, laurylamine, N,N-dimethylstearamine, N,N-dimethylstearylamine, N,N-dimethyloctylamine, ammonium, or acidic compounds such as alkylbenzenesulfonic acid, methanesulfonic acid, dialkylsulfosuccinic acid, naphthalenesulfonic acid, oleic acid, and naphthalenesulfonic acid-formaldehyde condensate.

[0071] The leveling agent is not particularly limited, and examples thereof include acetylene glycol, acetylene alcohol, and silicone surfactants.

[0072] [Manufacturing Method] The oil-based ink composition for writing instruments can be manufactured by a known method.

[0073] For example, it can be obtained by blending a medium, a compound represented by the general formula (1), a resin, and, if necessary, other colorants and additives in an appropriate temperature range and stirring and mixing them using a mixer, roll, homogenizer, disperser, etc. Also, media-type dispersers such as rotary shear homogenizers, ball mills, sand mills, attritors, and high-pressure counter-collision dispersers can be used.

[0074] The oil-based ink composition for writing instruments needs to ensure a certain amount of solid content. When the solid content decreases, the viscosity of the ink decreases, leading to ink dripping.

[0075] That is, the viscosity of the oil-based ink composition for writing instruments is preferably in the range of 100 to 3000 mPa·s at a shear rate of 38.30 (1 / s) in an atmosphere of 24.5 to 25.5 °C.

[0076] [Writing Instruments] The oil-based ink composition for writing instruments is filled and used in ball pens, sign pens, and marking pens.

[0077] A ballpoint pen will be described.

[0078] The structure and form of the ballpoint pen are not particularly limited. For example, a ballpoint pen can be mentioned which has an ink storage tube with a ball tip having a ball mounted on a ball receiving seat at the tip connected to the tip portion, and this tip protrudes from the tip of the shaft tube. After the oil-based ballpoint pen ink composition is filled from the opening of the ink storage tube to the base end, the opening at the base end is closed with an anti-backflow liquid plug or anti-backflow body.

[0079] As the ball rolls on the writing medium, the oil-based ballpoint pen ink composition is supplied to the surface of the ball from the gap between the ball tip and the ball, soaks into the writing medium, and a writing trace is formed.

[0080] <Water-based ink composition for writing instruments> Next, a water-based ink composition for writing instruments will be described.

[0081] The water-based ink composition for writing instruments contains an aqueous medium and a carrier dispersed in the aqueous medium, and is characterized in that the carrier carries a compound represented by the general formula (1).

[0082] [Carrier] The carrier carries a compound represented by the general formula (1), and as the state of the carrying, the compound represented by the general formula (1) may be in a state of being dispersed throughout, encapsulated inside, or present on the surface.

[0083] The main body constituting the carrier is not particularly limited, and examples thereof include resins and cellulose nanofibers.

[0084] [Resin] The method for producing resin particles carrying a compound represented by the general formula (1) is not particularly limited, and examples thereof include a bulk resin pulverization method, a suspension polymerization method, an emulsion polymerization method, a miniemulsion polymerization method, a phase inversion emulsification method, and the like.

[0085] The bulk resin pulverization method is a method of physically pulverizing a bulk resin obtained by polymerization in advance so as to contain a compound represented by the general formula (1) using a pulverizer or the like.

[0086] The suspension polymerization method is a method in which a polymerizable monomer in which a compound represented by the general formula (1) is dissolved is suspended in a liquid state in an aqueous medium in the presence of a dispersant, and the droplets are polymerized in this state.

[0087] The emulsion polymerization method is a method in which a polymerizable monomer is polymerized in a state of being emulsified in an aqueous medium in the presence of a compound represented by the general formula (1).

[0088] The miniemulsion polymerization method is a method in which a polymerizable monomer is dissolved or dispersed in a compound represented by the general formula (1), and strong stirring is performed in an aqueous medium in the presence of a surfactant to form resin particles.

[0089] The phase transfer emulsification method is a method in which a compound represented by the general formula (1) and a resin are dissolved in a solvent, strong stirring is performed in an aqueous medium in the presence of a surfactant to form resin particles, and then the solvent is distilled off.

[0090] As a method of making a compound represented by the general formula (1) present on the surface of resin particles produced in advance, for example, a physical staining method of attaching a compound represented by the general formula (1) to the surface of resin particles, swelling the resin particles with an organic solvent, and mixing with a compound represented by the general formula (1) to allow the compound represented by the general formula (1) to penetrate into the interior of the resin, and a chemical swelling method and the like can be mentioned.

[0091] Among the above, in order to solve the problems of the present invention, the emulsion polymerization method, the miniemulsion polymerization method, and the phase inversion emulsification method are preferable from the viewpoint of being able to sufficiently reduce the particle diameter of the resin particles and obtaining a resin with a high degree of coloring.

[0092] The aqueous ink composition for writing instruments is obtained by mixing and stirring a dispersion of a carrier carrying the general formula (1) in an aqueous medium, and, if necessary, other colorants and additives within an appropriate temperature range using a mixer, roll, homogenizer, disperser, etc. Further, it can be prepared by using a media type disperser such as a rotary shear type homogenizer, ball mill, sand mill, attritor, etc., and a high-pressure counter-collision type disperser.

[0093] As the carrier, it is preferable that the compound represented by the general formula (1) is in an encapsulated state. To encapsulate the compound represented by the general formula (1) in the carrier, for example, it can be produced by polymerizing using a hydrophobic monomer in which the compound represented by the general formula (1) is dissolved, or by polymerizing using a hydrophobic monomer adsorbed on the surface of the compound represented by the general formula (1).

[0094] Regarding the former, a detailed study has been reported in Colloid and Polymer Science (December 2003, Volume 282, p119 - 126). Further, as a specific example of the latter, a method of mixing a separately prepared dispersion of a colorant and a dispersion of a hydrophobic monomer and then polymerizing can be mentioned. Regarding this method, a detailed study has been reported in "Encapsulation of Carbon Black by Miniemulsion Polymerization", Macromolecular Chemistry and Physics (January 2001, Volume 202, p.51 - 60).

[0095] The content of the compound represented by the general formula (1) is preferably 0.4 times or more and 20 times or less in terms of mass ratio with respect to the content of the resin or cellulose nanofiber constituting the carrier. When the content of the compound represented by the general formula (1) is within the above range, the occurrence of skipping lines, streaks, and clogging of the tip can be suppressed better.

[0096] The resin constituting the carrier is selected according to the application. For example, a resin obtained by copolymerizing a hydrophilic polymerizable monomer such as acrylic acid, methacrylic acid, N-(2-hydroxyethyl)acrylamide, N-vinylpyrrolidone, a polymerizable monomer having an ammonium salt, etc. and a lipophilic polymerizable monomer such as acrylic acid ester, methacrylic acid ester, vinyl acetate, styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, p-t-butylstyrene, 4-methoxystyrene, 4-chlorostyrene, N-vinylcarbazole, etc. at an appropriate mixing ratio by a known method can be used.

[0097] (Meth)acrylic esters are not particularly limited, and examples thereof include methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, isobornyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 2-ethoxyethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, diethylaminoethyl (meth)acrylate, and the like. Other examples include monofunctional acrylates such as polyethylene glycol monoacrylate, polyethylene glycol monomethacrylate, polypropylene glycol monoacrylate, polypropylene glycol monomethacrylate, phenoxyethyl acrylate, and phenoxyethyl methacrylate; polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, polypropylene glycol diacrylate, polypropylene glycol dimethacrylate, trimethylolethane triacrylate, trimethylolethane trimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, trimethylolpropane diacrylate, trimethylolpropane dimethacrylate, neopentyl glycol diacrylate, neopentyl glycol dimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, pentaerythritol triacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, trimethylolpropane tri(acryloyloxypropyl) ether, and the like.

[0098] When polymerizing polymerizable monomers to obtain a resin constituting a carrier, an oil-soluble initiator, a water-soluble initiator, a photopolymerization initiator, a photoacid generator, etc. can be used.

[0099] The oil-soluble initiator is not particularly limited, and examples thereof include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile; peroxide-based initiators such as acetylcyclohexylsulfonyl peroxide, diisopropyl peroxydicarbonate, decanoyl peroxide, lauroyl peroxide, stearoyl peroxide, propionyl peroxide, acetyl peroxide, t-butylperoxy-2-ethylhexanoate, benzoyl peroxide, t-butylperoxyisobutyrate, cyclohexanone peroxide, methyl ethyl ketone peroxide, dicumyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, cumene hydroperoxide.

[0100] The water-soluble initiator is not particularly limited, and examples thereof include ammonium persulfate, potassium persulfate, 2,2'-azobis(N,N'-dimethylenebisobutyramidine) hydrochloride, 2,2'-azobis(2-aminodinopropane) hydrochloride, azobis(isobutylamidine) hydrochloride, sodium 2,2'-azobisisobutyronitrile sulfonate, ferrous sulfate or hydrogen peroxide.

[0101] Examples of the photopolymerization initiator include vicinal polyketoaldonyl compounds, α-carbonyl compounds, acyloin ethers, polyquinone compounds, combinations of triallylimidazole dimer and p-aminophenyl ketone, trioxadiazole compounds, etc. Among these, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone (trade name: Irgacure 369, manufactured by BASF) is preferable.

[0102] As the photoacid generator, known photoacid generators such as salts of onium ions such as sulfonium, iodonium, selenium, ammonium, and phosphonium with anions can be used.

[0103] Examples of sulfonium ions include triphenylsulfonium, tri-p-tolylsulfonium, tri-o-tolylsulfonium, tris(4-methoxyphenyl)sulfonium, 1-naphthyldiphenylsulfonium, diphenylphenacylsulfonium, phenylmethylbenzylsulfonium, 4-hydroxyphenylmethylbenzylsulfonium, dimethylphenacylsulfonium, phenacyltetrahydrothiophenium, and the like.

[0104] Examples of the above iodonium ions include diphenyliodonium, di-p-tolyliodonium, bis(4-dodecylphenyl)iodonium, bis(4-methoxyphenyl)iodonium, (4-octyloxyphenyl)phenyliodonium, and the like.

[0105] Examples of selenium ions include triarylselenium such as triphenylselenium, tri-p-tolylselenium, tri-o-tolylselenium, tris(4-methoxyphenyl)selenium, 1-naphthyldiphenylselenium, tris(4-fluorophenyl)selenium, tri-1-naphthylselenium, and tri-2-naphthylselenium.

[0106] Examples of ammonium ions include tetraalkylammonium such as tetramethylammonium, ethyltrimethylammonium, diethyldimethylammonium, triethylmethylammonium, tetraethylammonium, trimethyl-n-propylammonium, trimethylisopropylammonium, trimethyl-n-butylammonium, and trimethylisobutylammonium.

[0107] Examples of phosphonium ions include tetraphenylphosphonium, tetra-p-tolylphosphonium, tetrakis(2-methoxyphenyl)phosphonium, triphenylbenzylphosphonium, triphenylphenacylphosphonium, triphenylmethylphosphonium, triethylbenzylphosphonium, tetraethylphosphonium, and the like.

[0108] Examples of anions include perhalate ions such as ClO 4 - and BrO 4 - ; halogenated sulfonate ions such as FSO 3 - and ClSO 3 - ; sulfate ions such as CH 3 SO 4 - and CF 3 SO 4 - and HSO 4 - ; carbonate ions such as HCO 3 - and CH 3 CO 3 - ; aluminate ions such as AlCl 4 - and AlF 4 - ; hexafluorobismuthate ions, carboxylic acid ions such as CH 3 COO - and CF 3 COO - and C 6 H 5 COO - and CH 3 C 6 H 4 COO - and C 6 F 5 COO - and CF 3 C 6 H 4 COO - ; and B(C 6 H 5 ) 4 - and CH 3CH 2 CH 2 CH 2 B(C 6 H 5 ) 3 - Arylborate ions such as etc.; thiocyanate ions, nitrate ions and the like can be mentioned, but are not limited thereto.

[0109] The concentration of the polymerization initiator is preferably 0.01% by mass or more and 10% by mass or less, more preferably 0.03% by mass or more and 5% by mass or less, based on the total mass of the monomer components.

[0110] The emulsifier used in the polymerization of the polymerizable monomer is not particularly limited, and a cationic surfactant, an anionic surfactant, a nonionic surfactant, etc. can be used.

[0111] Specifically, examples of the cationic surfactant include dodecylammonium chloride, dodecylammonium bromide, dodecyltrimethylammonium bromide, dodecylpyridinium chloride, dodecylpyridinium bromide, hexadecyltrimethylammonium bromide, and the like.

[0112] Examples of the anionic surfactant include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, sodium lauryl sulfate, and the like.

[0113] Furthermore, examples of the nonionic surfactant include dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, nonylphenyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, monodecanoyl sucrose, lauric acid monoglyceride (manufactured by Sun Chemical), and the like.

[0114] The content of the resin in the carrier is preferably 5 to 50% by mass, more preferably 10 to 40% by mass, based on the mass (total solid content) of the aqueous ink composition for writing instruments. By being in the above range, the sensitivity to exposure and the strength of the drawing paper can be further improved, and the adhesiveness of the aqueous ink composition for writing instruments also becomes good.

[0115] [Cellulose nanofiber] The cellulose nanofibers contained in the carrier are selected according to the application. For example, they are obtained by chemically and / or mechanically defibrating plant fibers, and are ultrafine fibers with an average width of about several nm to 20 nm and an average length of about 0.5 μm to several μm. The size (fiber diameter) of these cellulose nanofibers varies depending on the type of cellulose nanofiber. Also, a fiber diameter that is a suitable range in terms of thickening action, stability over time, color development, etc. is selected within a range that does not inhibit the characteristics in various applications.

[0116] As materials containing cellulose fibers, plants such as wood, bamboo, kenaf, hemp, jute, wood pulp, waste paper, crystalline cellulose, agricultural crop residues, recycled pulp, animals such as jellyfish, algae, microorganisms, etc. can be used.

[0117] Examples of the apparatus for performing defibrating treatment include a rotary shear type homogenizer, a high-pressure homogenizer, a high-pressure homogenization apparatus, a ball mill, a sand mill, an attritor, a high-pressure counter-collision type disperser, a grinder, a conical refiner, etc.

[0118] Cellulose nanofibers are commercially available and can also be used. Examples of commercially available products include Reocrist I-2AX, CNF 03, CNF 04 (manufactured by Daiichi Chemical Industry Co., Ltd.), ELLEX-S (manufactured by Oji Paper Co., Ltd.), nano forest-S (manufactured by Chugoku Pulp Industry Co., Ltd.).

[0119] The blending amount of the cellulose nanofibers is preferably 0.001 to 40 parts by mass, more preferably 0.01 to 10 parts by mass, and still more preferably 0.05 to 5 parts by mass per 100 parts by mass of the aqueous medium contained in the aqueous ink composition for writing instruments.

[0120] The method for loading the compound represented by the general formula (1) on the cellulose nanofibers is not particularly limited. For example, in an aqueous medium, after bringing the cellulose nanofibers into contact with the compound represented by the general formula (1), heating or oxidation treatment is performed as necessary, and then the medium is distilled off to obtain the dyed cellulose nanofibers. When bringing them into contact, a pH adjuster, a developer, a dispersant, etc. may be added.

[0121] The aqueous coloring solution may be the same system as that used when dyeing the cellulose nanofibers, or the dried and dyed cellulose nanofibers may be taken out and dispersed again in an aqueous medium or the like.

[0122] [Medium] When using an aqueous ink composition for writing instruments, it is preferable to use a mixture of water and a water-soluble organic solvent as the aqueous medium. Examples of the water-soluble organic solvent to be contained in the aqueous medium include alcohols, polyhydric alcohols, polyglycols, glycol ethers, nitrogen-containing polar solvents, sulfur-containing polar solvents, and the like. Specifically, ethylene glycol, diethylene glycol, triethylene glycol, 3-methyl-1,3-butanediol, 1,3-butanediol, polyethylene glycol, glycerin, ethylene glycol monomethyl ether, and diethylene glycol monomethyl ether can be mentioned. These water-soluble organic solvents contribute to maintaining the moisture retention of the writing instrument ink, improving the solubility of the coloring material, and effectively penetrating the writing instrument ink into the recording paper. In the aqueous medium in the writing instrument ink, the ratio (by mass) of water to the water-soluble organic solvent is preferably water / water-soluble organic solvent = 9 / 1 to 1 / 9. More preferably, it is 8 / 2 to 2 / 8, and even more preferably, it is 7 / 3 to 3 / 7. By doing so, the dispersibility or solubility of the coloring material containing compound (1) in the ink can be made good.

[0123] [Additives] The aqueous ink composition for writing instruments can be suitably used for aqueous ballpoint pens, gel ink aqueous ballpoint pen inks, sign pens, marking pens, etc. Additives such as dispersants, lubricants, pH adjusters, rust preventives, preservatives, or antibacterial agents may be appropriately added within a range that does not inhibit the characteristics in various applications.

[0124] The lubricant is not particularly limited. Examples include nonionic ones such as fatty acid esters of polyhydric alcohols, higher fatty acid esters of sugars, and alkyl phosphoric acid esters, anionic ones such as alkyl sulfonates of higher fatty acid amides and alkyl allyl sulfonates, derivatives of polyalkylene glycols, fluorine-based surfactants, and polyether-modified silicones.

[0125] The pH adjuster is not particularly limited, and examples thereof include sodium hydroxide, urea, monoethanolamine, diethanolamine, triethanolamine, sodium tripolyphosphate, sodium carbonate, and alkali metal salts of phosphoric acid. For example, from the viewpoints of usability, safety, and the stability of the ink itself, it is preferably adjusted to a pH of 4 to 11, and more preferably 5 to 10.

[0126] The rust inhibitor is not particularly limited, and examples thereof include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin, and phosphate ester compounds.

[0127] The preservative or antibacterial agent is not particularly limited, and examples thereof include phenol, sodium benzoate, benzimidazole-based compounds, sodium omadine, sodium pentachlorophenol, sodium sorbate, and 1,2-benzisothiazolin-3-one.

[0128] In addition, the aqueous ink composition for writing instruments may contain a pigment.

[0129] The pigments that can be used are not particularly limited, and can be selected from among inorganic and organic pigments conventionally used for writing instruments such as aqueous ballpoint pens.

[0130] Examples of the inorganic pigments include carbon black and metal powder.

[0131] Examples of the organic pigments include azo pigments, phthalocyanine pigments, perylene pigments, and quinacridone pigments. The content can be 0.1 to 50 parts by mass, preferably 0.5 to 30 parts by mass, per 100 parts by mass of the aqueous medium.

[0132] When using a pigment in combination, it is preferable to use a dispersant. As the dispersant, an ionic surfactant, a nonionic surfactant, a polymeric surfactant, a water-soluble resin, etc. are used within a range that does not inhibit the properties in the application.

[0133] [Manufacturing Method] The aqueous ink composition for writing instruments can be manufactured by a known method.

[0134] For example, it can be obtained by blending an aqueous ink composition for writing instruments and, if necessary, other colorants and additives within an appropriate temperature range and stirring and mixing them using a mixer, roll, homogenizer, disper, etc. Also, a media type disperser such as a rotary shear type homogenizer, ball mill, sand mill, attritor, etc., and a high-pressure counter-collision type disperser can be used.

[0135] The aqueous ink composition for writing instruments thus manufactured is filled into ball pens, sign pens, and marking pens.

Examples

[0136] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples. In the text, "parts" and "%" represent "parts by mass" and "% by mass" unless otherwise specified.

[0137] The compound represented by the general formula (1) was synthesized by a known method. The identification of the obtained compound was 1 performed using an H nuclear magnetic resonance spectroscopic analysis ( 1 H-NMR) apparatus (ECA-400, manufactured by JEOL Ltd.) and an LC / TOF MS apparatus (LC / MSD TOF, manufactured by Agilent Technologies).

[0138] [Manufacture of Oil-Based Ink Composition for Writing Instruments] [Examples 1 to 22, Comparative Examples 1 to 14] The constituent materials shown in Table 1 and Table 2 were used. First, resin was added to the medium, heated to 70 °C and dissolved, then cooled to room temperature, a colorant and other constituent materials were added, and dispersed for 3 hours using an attritor (manufactured by Mitsui Mining Co., Ltd.) to produce an oil-based ink composition for writing instruments.

[0139] In addition, Comparative Compounds (1) to (6) in Table 2 are the following compounds.

[0140] [Chemical formula]

[0141] [Table 1]

[0142] [Table 2]

[0143] [Evaluation of dissolution stability] 20 mL of each of the oil-based ink compositions for writing instruments obtained above was added to a 50 mL sample bottle and sealed, and left for 1 month under low temperature (0 °C) and high temperature (60 °C) conditions to evaluate the dissolution stability of the ink composition. The presence or absence of aggregates in the ink composition was visually observed using a phase contrast microscope (BX53, manufactured by OLYMPUS). A: There are no aggregates in the ink composition. B: Slight aggregates have occurred in the ink composition. C: Aggregates have occurred in the ink composition.

[0144] [Evaluation of bleeding (initial writing property) during writing] Each of the oil-based ink compositions for writing instruments obtained above was filled into an ink storage tube made of a polypropylene tube with an inner diameter of 1.2 mm and a length of 140 mm. An evaluation test ballpoint pen equipped with this ink storage tube and a phosphor bronze tip was produced (ball diameter 0.7 mm).

[0145] The cap of the test ballpoint pen was removed and left for 1 hour at a humidity of 65% under low temperature (0°C) and high temperature (60°C) conditions. Then, using JIS P3201 writing paper, a circle was handwritten.

[0146] The scratch evaluation during writing was carried out according to the following evaluation criteria. A: No scratches occurred under both low temperature (0°C) and high temperature (60°C) conditions. B: Slight scratches occurred under either one or both of the low temperature (0°C) and high temperature (60°C) conditions. C: Clear scratches occurred under either one or both of the low temperature (0°C) and high temperature (60°C) conditions.

[0147] [Writing quality evaluation] The writing quality evaluation was carried out using the created ballpoint pen. The writing quality evaluation was performed according to the following evaluation criteria to determine whether there were any breaks or scratches in the handwriting and whether the handwriting density remained unchanged and the handwriting continued to be stable. A: Under both low temperature (0°C) and high temperature (60°C) conditions, there were no breaks or scratches in the handwriting, and there was no change in the handwriting density. B: Under at least one of the low temperature (0°C) and high temperature (60°C) conditions, slight breaks or scratches occurred in the handwriting, or there was a slight change in the handwriting density. C: Under at least one of the low temperature (0°C) and high temperature (60°C) conditions, obvious breaks or scratches occurred in the handwriting, and there was a change in the handwriting density.

[0148] [Handwriting fastness evaluation] For the handwriting fastness evaluation, using the created ballpoint pen, writing was done for 20 cm with a constant pen pressure to create an image sample. The image sample was put into a xenon test device (Atlas Weather Ometer Ci4000, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and exposed for 10 hours under the conditions of (illuminance: 0.28 W / m at 340 nm 2 , black panel temperature: 40°C, relative humidity: 50%). The spectra before and after exposure were read with a scanner. Taking the initial optical density as OD 0 and the optical density after 5 hours of exposure as OD 5 , the optical density residual rate was defined as follows.

[0149] Optical density residual rate (%) = (OD 5 / OD 0 ) × 100 The evaluation criteria are as follows. A: The optical density residual rate is 85% or more B: The optical density residual rate is 70% or more and less than 85% C: The optical density residual rate is less than 70% The evaluation results are shown in Table 3.

[0150]

Table 3

[0151] As described above, by using the compound of the present invention, it is possible to provide an oil-based ink composition for writing instruments in which aggregation of the colorant is suppressed even under low-temperature and high-temperature conditions. Furthermore, by using such an oil-based ink composition for writing instruments, it is possible to provide a ballpoint pen that suppresses the bleeding phenomenon during writing, has a good writing feel with few streaks or bleeding in the handwriting, and has high handwriting fastness.

[0152] <Manufacture of aqueous ink composition for writing instruments> <Example 23> After adding 5 parts of compound (1-2), 1 part of methanol, and 0.5 part of cellulose nanofiber (Reocrista I-2AX), 99 parts of ion-exchanged water were added. The mixture was heated to an internal temperature of 80 °C and stirred for 2 hours while removing methanol. After cooling to room temperature, it was dispersed for 5 minutes with a homogenizer to prepare an aqueous ink composition for writing instruments in which cellulose nanofibers dyed with compound (1) were dispersed in the medium.

[0153] <Examples 24 to 44, Comparative Examples 15 to 32> In Example 23, an aqueous ink composition for a writing instrument containing cellulose nanofibers dyed with a compound and an aqueous ink composition for a comparative example were prepared by the same procedure except that the compounds and cellulose nanofibers were changed to those shown in Table 4. Note that cellulose nanofibers are available from Leocrysta I-2AX, CNF 03, CNF 04 (Dai-ichi Kogyo Seiyaku Co., Ltd.), ELLEX-S (Daioh Paper Co., Ltd.), and nanoforest-S (Chuetsu Pulp Industry Co., Ltd.).

[0154] Note that the comparative compounds (1) to (3) are the same as those described above.

[0155]

Table 4

[0156] <Example 45> 10g of cyclohexyl methacrylate, 8g of n-butyl methacrylate, 2g of triallyl isocyanurate, and 0.5g of 2,2'-azobis-(2-methylbutyronitrile) were mixed and stirred at 100 rpm for 1 hour. The obtained mixture was added dropwise to 70 g of an aqueous solution (concentration 0.3%) of 0.05 g of lauric acid monoglyceride (manufactured by Taiyo Kagaku Co., Ltd.), and stirred at 300 rpm for 1 hour. Dispersed with a homogenizer for 1 hour (dispersion liquid A).

[0157] 10 g of compound (1-5) was added to 110 g of an aqueous solution of lauric acid monoglyceride (concentration 2.7%), stirred at 300 rpm for 2 hours, and then dispersed with a homogenizer for 1 hour (dispersion liquid B).

[0158] 20 g of dispersion liquid A and 80 g of dispersion liquid B were mixed and stirred at 300 rpm for 1 hour. Then, dispersed with a homogenizer for 5 minutes and stirred for 1 hour. After stirring, the mixture was polymerized under a nitrogen atmosphere at 70°C for 8 hours to obtain a dispersion containing a carrier in which compound (1-5) was dispersed in resin particles. This was filtered through a 5.0 μm filter to remove coarse particles to obtain a water-based ink composition for writing instruments. The average particle size of the resin particles in the obtained water-based ink composition for writing instruments was 58 nm.

[0159] <Examples 46 to 50> In Example 45, an aqueous ink composition for writing instruments in which the compound represented by the general formula (1) was dispersed or encapsulated in the carrier was prepared by the same operation except that the materials used were changed to those shown in Table 5.

[0160]

Table 5

[0161] [Evaluation of dispersion stability] 20 mL of each of the aqueous ink compositions for writing instruments obtained above was added to a 50 mL sample bottle and sealed, and left for 1 month under low temperature (0 °C) and high temperature (60 °C) conditions to evaluate the dispersion stability of the ink composition. The presence or absence of aggregates in the ink composition was observed using a phase contrast microscope (BX53, manufactured by OLYMPUS). A: No aggregates were observed in the ink composition. B: Slight aggregates occurred in the ink composition. C: Aggregates clearly occurred in the ink composition.

[0162] [Evaluation of streaks (initial writing quality) during writing] Each of the aqueous ink compositions for writing instruments obtained above was filled into an ink storage tube made of a polypropylene tube having an inner diameter of 1.2 mm and a length of 140 mm. An evaluation test ballpoint pen equipped with this ink storage tube and a phosphor bronze tip was prepared (ball diameter 0.7 mm).

[0163] After removing the cap of the test ballpoint pen and leaving it for 1 hour at a low temperature (0 °C) and a high temperature (60 °C) under a humidity of 65%, a circle was handwritten using JIS P3201 writing paper. The evaluation of streaks during writing was performed according to the following evaluation criteria. A: No streaks occurred under both low temperature (0 °C) and high temperature (60 °C) conditions. B: Streaks occurred under either one or both of the low temperature (0 °C) and high temperature (60 °C) conditions. C: Blurring was clearly observed under either or both of the low temperature (0 °C) and high temperature (60 °C) conditions.

[0164] [Writing feel evaluation] Using the prepared ballpoint pen, a writing feel evaluation was conducted. The writing feel evaluation was performed according to the following evaluation criteria to determine whether there were skips or blurs in the handwriting and whether the handwriting density remained unchanged and the handwriting continued to be stable. A: Under both the low temperature (0 °C) and high temperature (60 °C) conditions, there were no skips or blurs in the handwriting, and there was no change in the handwriting density. B: Under at least one of the low temperature (0 °C) and high temperature (60 °C) conditions, slight skips or blurs occurred in the handwriting, or there was a slight change in the handwriting density. C: Under at least one of the low temperature (0 °C) and high temperature (60 °C) conditions, obvious skips or blurs occurred in the handwriting, and there was a change in the handwriting density.

[0165] [Handwriting fastness evaluation] Using the prepared ballpoint pen, writing was done for 20 cm with a pen pressure of a certain constant pressure to create an image sample. The image sample was put into a xenon test device (Atlas Weather Ometer Ci4000, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and exposed for 10 hours under the conditions of (illuminance: 0.28 W / m at 340 nm 2 , black panel temperature: 40 °C, relative humidity: 50%). The spectra before and after exposure were read with a scanner. Taking the initial optical density as OD 0 and the optical density after 5 hours of exposure as OD 5 , the optical density residual rate was defined as follows.

[0166] Optical density residual rate (%) = (OD 5 / OD 0 ) × 100 The evaluation criteria are as follows. A: The optical density residual rate is 85% or more B: The optical density residual rate is 70% or more and less than 85% C: The optical density residual rate is less than 70% The evaluation results are shown in Tables 6 and 7.

[0167]

Table 6

[0168]

Table 7

[0169] As shown by the above results, the present invention provides an aqueous ink composition for writing instruments with high dispersion stability of the carrier in an aqueous medium. Furthermore, by using such an aqueous ink composition for writing instruments, it is possible to provide a ballpoint pen that suppresses the bleeding phenomenon during writing, has a good writing feel with few skips and bleeding in the handwriting, and has high handwriting fastness.

Industrial Applicability

[0170] The oil-based ink composition for writing instruments of the present invention suppresses the aggregation of the colorant even under low-temperature and high-temperature conditions. Also, the aqueous ink composition for writing instruments of the present invention is excellent in the dispersion stability of the carrier.

[0171] And a ballpoint pen having the oil-based ink composition for writing instruments or the aqueous ink composition for writing instruments of the present invention suppresses the bleeding phenomenon during writing, has a good writing feel with few skips and bleeding in the handwriting, and has high handwriting fastness.

Claims

1. A medium containing an alcohol or a glycol ether, a resin present in a dissolved state in said medium, and A colorant containing a compound represented by the following general formula (1): An oil-based ink composition for a writing instrument comprising: 【Chemistry 1】 [R １ ~R ２ are both 2-ethylhexyl groups or both n-butyl groups, R ３ represents a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms, R ４ represents any functional group selected from the group consisting of a t-butyl group, an isopropyl group, a phenyl group, and a benzyl group.

2. 2. The oil-based ink composition for writing instruments according to claim 1, wherein the resin comprises a butyral resin or a ketone resin.

3. A ballpoint pen comprising the oil-based ink composition for a writing instrument according to claim 1 or 2.

4. an aqueous medium, and a carrier dispersed in the aqueous medium; A water-based ink composition for a writing instrument comprising: The aqueous ink composition for writing instruments is characterized in that the carrier carries a compound represented by general formula (1). 【Chemistry 2】 [R １ ~R ２ are both 2-ethylhexyl groups or both n-butyl groups, R ３ represents a linear alkyl group having 1 to 4 carbon atoms or a branched alkyl group having 3 to 4 carbon atoms, R ４ represents any functional group selected from the group consisting of a t-butyl group, an isopropyl group, a phenyl group, and a benzyl group.

5. The aqueous ink composition for writing instruments according to claim 4, wherein the carrier is a resin or a cellulose nanofiber.

6. A ballpoint pen comprising the aqueous ink composition for a writing instrument according to claim 4 or 5.

Images