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

Abstract

To provide an oily ink composition for a writing instrument which suppresses aggregation of a coloring agent in an ink composition under low temperature and high temperature conditions, and has high dissolution stability, and an oily ink composition for a writing instrument that enables provision of a ball point pen which suppresses a blurring phenomenon at the beginning of writing, has such good writing feeling as to prevent skipping and blurring in handwriting, and has handwriting fastness.SOLUTION: There are provided an oily ink composition for a writing instrument which contains a medium containing alcohol or glycol ether, a resin dissolved in the medium and a coloring agent containing a compound represented by general formula (1); and an aqueous ink composition for a writing instrument which contains a carrier that is dispersed in an aqueous medium and carries the general formula (1).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an oil-based ink composition for a writing instrument, a water-based ink composition for a writing instrument, and a ballpoint pen. [Background technology]

[0002] In recent years, there has been a rapid increase in user demand for writing instruments (especially ballpoint pens) that differ in ink and function, such as writing feel, writing start (initial writing performance), and stable and continuous writing. Ballpoint pens can be broadly classified into oil-based ballpoint pens, water-based ballpoint pens, gel ink ballpoint pens, etc. Oil-based inks come in a variety of colors, including black, red, blue, pink, green, and orange, and are usually produced by dissolving or dispersing a colorant in an organic solvent. In order to further improve writing performance, resins, surfactants, additives, and other ingredients are added depending on the application. Dyes, pigments, and mixtures thereof are used as colorants contained in oil-based inks. For example, oil-based inks using pigments have excellent fastness of handwriting, but the pigments tend to aggregate and settle in the ink, which can cause problems in handwriting. In contrast, oil-based inks using dyes have the characteristic that the dyes are easily dissolved in solvents, so they are less likely to aggregate or settle compared to pigments, but they tend to have inferior water resistance and weather resistance. As for dyes, various dyes such as acid dyes, basic dyes, and processed dyes such as salt-forming dyes are known. For example, inks using triphenylmethane dyes as colorants (Patent Document 1) and inks using a mixture of dyes and pigments (Patent Document 2) have been reported. On the other hand, in the case of water-based ink, in addition to water-soluble dyes, pigments and oil-based dyes are dispersed as colorants. In recent years, cellulose nanofibers, which can be obtained by chemically or mechanically defibrating plant fibers, have been attracting attention, and research into their use in various fields is active, with examples of cellulose nanofibers being used in writing instruments being reported (Patent Documents 3-4). In addition, a method of encapsulating a colorant by emulsion polymerization of a monomer has been reported (Patent Documents 5-6). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2015-193682 A [Patent Document 2] JP 2003-113339 A [Patent Document 3] JP 2017-105907 A [Patent Document 4] JP 2017-125135 A [Patent Document 5] JP2016-196623 Public Relations [Patent Document 6] JP2019-112561 Public Relations Summary of the Invention [Problem to be solved by the invention]

[0004] The dyes described in Patent Documents 1 and 2 tend to aggregate, and when the ink solvent at the tip of the ball tip evaporates, the ink thickens, which can cause smearing when writing. In addition, triphenylmethane dyes in particular have low solubility stability, so depending on the usage environment, there are issues such as a poor writing feel (handwriting density does not change and handwriting continues to be produced stably) and low handwriting fastness. Since dyes have low compatibility with carriers (resins and cellulose nanofibers), the dye, resin, and cellulose nanofibers each aggregate, which causes the resin and cellulose nanofiber to not be uniformly dyed with the dye. In addition, ink compositions containing resins and cellulose nanofibers in such an unevenly dyed state have the problem of poor storage stability. On the other hand, even with the method of incorporating colorants by polymerization, there is also the problem of poor handwriting fastness. [Means for solving the problem]

[0005] The present invention relates to a medium containing an alcohol or a glycol ether; a resin that dissolves in the medium; and A colorant containing a compound represented by the following general formula (1):

[0006] [ka] [In formula (1), R1 and R2 each independently represent a substituted phenyl group or an unsubstituted phenyl group; R3 and R4 each independently represent an alkyl group having a substituent and having from 2 to 12 carbon atoms or an unsubstituted alkyl group, a cyano group, a trifluoromethyl group, or a halogen atom; R5 and R6 each independently represent a hydrogen atom or an alkyl group; R7 represents a structure represented by the following formula (2) or (3):

[0007] [ka] In formula (2), R8 is -SO3 - R represents a hydrogen atom or a halogen atom; In formula (3), R 10 ~R 12 each independently represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, X - represents an anion and may be absent when there is at least one anionic substituent in the molecule. The present invention relates to an oil-based ink composition for a writing instrument, comprising: The present invention also relates to an aqueous ink composition for a writing instrument, characterized in that it contains a carrier carrying the above general formula (1) dispersed in an aqueous medium, and a ballpoint pen using the ink composition. Effect of the Invention

[0008] According to the present invention, the oil-based ink composition for writing instruments has high dissolution stability because the aggregation of the colorant in the ink composition is suppressed even under low and high temperature conditions. Furthermore, by using the oil-based ink composition for writing instruments, it is possible to provide a ballpoint pen that suppresses the phenomenon of smearing at the start of writing, has a good writing feel without line skipping or smearing in the handwriting (handwriting density does not change and handwriting continues to be stably produced) and has high handwriting fastness. In addition, the aqueous ink composition for writing instruments has high dispersion stability in an aqueous medium of the carrier carrying general formula (1). In other words, this indicates that when the carrier is prepared by a polymerization method, polymerization inhibition with general formula (1) does not occur, and when cellulose nanofibers are used, compatibility with general formula (1) is high. Furthermore, by using the aqueous ink composition for writing instruments, it is possible to provide a ballpoint pen that suppresses the phenomenon of smearing at the start of writing, has a good writing feel without line skipping or smearing in the handwriting (handwriting density does not change and handwriting continues to be stably produced) and has high handwriting fastness. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] Hereinafter, an embodiment of the present invention will be described in detail.

[0010] [Coloring agent] First, the compound represented by formula (1) used as a colorant will be described.

[0011] [ka] [In formula (1), R1 and R2 each independently represent a substituted phenyl group or an unsubstituted phenyl group; R3 and R4 each independently represent an alkyl group having a substituent and having from 2 to 12 carbon atoms or an unsubstituted alkyl group, a cyano group, a trifluoromethyl group, or a halogen atom; R5 and R6 each independently represent a hydrogen atom or an alkyl group; R7 represents a structure represented by formula (2) or (3);

[0012] [ka] In formula (2), R8 is -SO3 - R represents a hydrogen atom or a halogen atom; In formula (3), R 10 ~R 12 each independently represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, X - represents an anion and may be absent when there is at least one anionic substituent in the molecule.

[0013] Even if the compound has a structure similar to that of the general formula (1), its properties differ greatly depending on the delicate balance of the electron donating groups and the electron donating groups due to the substituents. In the case of the substituents other than R1 to R4 in the general formula (1) of the present invention, it was found by the comparative examples described later that the solubility of the compound in the solvent decreases, and the aggregation of the colorant is promoted in the ink composition under low and high temperature conditions, resulting in low solubility stability.

[0014] In contrast, the compound of the present invention solves the problem. That is, R1 and R2 each independently represent a phenyl group having a substituent or an unsubstituted phenyl group, R3 and R4 each independently represent an alkyl group having a substituent with 2 to 12 carbon atoms or an unsubstituted alkyl group, a cyano group, a trifluoromethyl group, or a halogen atom, and one methylene group is present between the nitrogen atom and R3 and between the nitrogen atom and R4.

[0015] When R1 and R3, and R2 and R4 are asymmetric and bulky, the three substituents at the N-position form a three-dimensional twisted structure. It is speculated that this suppresses interactions between compounds within or between molecules, suppressing aggregation of the colorant in the ink composition even under low and high temperature conditions, and increasing the solubility stability. In addition, when R1 and R2 are substituted phenyl groups or unsubstituted phenyl groups directly bonded to the nitrogen atom, the charge is delocalized, resulting in stability. As a result, it is speculated that a ballpoint pen with high handwriting fastness can be provided.

[0016] In the aqueous ink composition for writing instruments, the carrier having the general formula (1) has high dispersion stability in an aqueous medium.

[0017] Conventionally, the compatibility of compounds that are substituents other than R1 to R4 in the general formula (1) of the present invention with cellulose nanofibers was low. As a result, dye molecules or cellulose nanofibers were strongly aggregated together. The compound represented by the following general formula (1) of the present invention has high compatibility with cellulose nanofibers because the intramolecular or intermolecular interactions between compounds are suppressed, and therefore the intramolecular or intermolecular interactions between compounds are suppressed, making it possible to control aggregation. As a result, a water-based ink composition for writing instruments with excellent storage stability is obtained, which contains cellulose nanofibers that are nearly uniformly colored.

[0018] On the other hand, when a monomer and a colorant (particularly a dye) are mixed and polymerized, the colorant causes polymerization inhibition, and there are problems such as the colorant not being polymerized, not being uniformly dispersed, and not being incorporated. In the case of a substituent other than R1 to R4 in the general formula (1) of the present invention, polymerization inhibition occurs. However, when preparing the carrier of the present invention, it has been found that the general formula (1) does not cause polymerization inhibition because the interaction between compounds within or between molecules is suppressed.

[0019] First, the compound represented by the above general formula (1) will be described.

[0020] In formula (1), the substituent of the "substituted phenyl group" in R1 and R2 is not particularly limited, and examples thereof include the following: a linear, branched, or cyclic alkyl group having 1 to 20 carbon atoms, an alkoxy group, a cyano group, a halogen atom, a sulfo group (-SO3H), a sulfonate ester group, a sulfonamide group, a sulfonate group, a benzenesulfonyl group, a trifluoromethanesulfonyl group, and the like.

[0021] In formula (1), the alkyl group substituted on the phenyl group in R1 and R2 is not particularly limited, but examples thereof include the following: methyl group, ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, cyclohexyl group, 2-ethylhexyl group, octyl group, decyl group, dodecyl group, etc.

[0022] Among these, methyl groups, n-butyl groups, n-hexyl groups, 2-ethylhexyl groups, octyl groups, and decyl groups are preferred because they suppress aggregation of the colorant in the ink composition even under low and high temperature conditions, thereby increasing the dissolution stability.

[0023] In formula (1), the alkoxy group substituting the phenyl group in R1 and R2 is not particularly limited, but includes the following: methoxy group, ethoxy group, propoxy group, n-butoxy group, t-butoxy group, hexyloxy group, 2-ethylhexyloxy group, octyloxy group, decyloxy group, dodecyloxy group, etc.

[0024] Among these, n-butoxy, hexyloxy, 2-ethylhexyloxy, octyloxy, and decyloxy groups are preferred because they suppress aggregation of the colorant in the ink composition and increase the dissolution stability even under low and high temperature conditions.

[0025] In formula (1), the halogen atom substituted on the phenyl group in R1 and R2 is not particularly limited, but examples thereof include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Among these, a fluorine atom or a chlorine atom is preferred because it suppresses aggregation of the colorant in the ink composition even under low and high temperature conditions, thereby increasing the dissolution stability.

[0026] In formula (1), the sulfonate ester group substituted on the phenyl group in R1 and R2 is not particularly limited, and examples thereof include the following: methyl sulfonate group, ethyl sulfonate group, propyl sulfonate group, butyl sulfonate group, hexyl sulfonate group, octyl sulfonate group, etc. Among these, butyl sulfonate group and hexyl sulfonate group are preferred because they suppress aggregation of the colorant in the ink composition even under low and high temperature conditions, thereby increasing the dissolution stability.

[0027] In formula (1), the sulfonamide group substituting the phenyl group in R1 and R2 is not particularly limited, but examples thereof include the following: N-methylsulfonamide group, N,N-dimethylsulfonamide group, N-ethylsulfonamide group, N,N-diethylsulfonamide group, N-propylsulfonamide group, N,N-dipropylsulfonamide group, N-butylsulfonamide group, N,N-dibutylsulfonamide group, N-pentylsulfonamide group, N,N-dipentylsulfonamide group, N-hexylsulfonamide group, N,N-dihexylsulfonamide group, N-octylsulfonamide group, N,N-dioctylsulfonamide group, N-(2-ethyl N,N-bis(2-ethylhexyl)sulfonamide group, N-(1-methylhexyl)sulfonamide group, N-(1-methylheptyl)sulfonamide group, N-methyl-N-butylsulfonamide group, N-methyl-N-pentylsulfonamide group, N-methyl-N-hexylsulfonamide group, N-methyl-N-octylsulfonamide group, N-phenylsulfonamide group, N-(p-methylphenyl)sulfonamide group, N-pyrrolidylsulfonyl group, N-piperidylsulfonyl group, and the like.

[0028] Among these, the following are preferred because they suppress aggregation of the colorant in the ink composition and increase the dissolution stability even under low and high temperature conditions: N,N-dibutylsulfonamido group, N,N-dipentylsulfonamido group, N,N-dihexylsulfonamido group, N,N-dioctylsulfonamido group, and N,N-bis(2-ethylhexyl)sulfonamido group.

[0029] In the formula (1), the sulfonate group substituted on the phenyl group in R1 and R2 is not particularly limited, but examples thereof include lithium sulfonate, sodium sulfonate, and potassium sulfonate.

[0030] In formula (1), the unsubstituted alkyl groups for R3 and R4 are not particularly limited, but the following are preferred because they suppress aggregation of the colorant in the ink composition and increase the dissolution stability even under low and high temperature conditions: ethyl group, n-propyl group, iso-propyl group, n-butyl group, sec-butyl group, tert-butyl group, n-hexyl group, cyclohexyl group, 2-ethylhexyl group, heptyl group, octyl group, decyl group, dodecyl group, etc.

[0031] In formula (1), the substituent of the alkyl group having the substituents R3 and R4 is not particularly limited, but a methoxy group, a bromine atom, a chlorine atom, a fluorine atom, a cyano group, a trifluoromethyl group, etc. are preferred because they result in a compound that suppresses aggregation of the colorant in the ink composition and increases the dissolution stability even under low and high temperature conditions.

[0032] In formula (1), the halogen atoms for R3 and R4 are not particularly limited, but examples thereof include a bromine atom, a chlorine atom, a fluorine atom, and an iodine atom. Among these, a chlorine atom and a fluorine atom are preferred because they suppress aggregation of the colorant in the ink composition even under low-temperature and high-temperature conditions, thereby resulting in a compound with high dissolution stability.

[0033] In formula (1), the alkyl group of R5 and R6 is not particularly limited, but examples thereof include a methyl group, an ethyl group, an n-propyl group, an iso-propyl group, an n-butyl group, etc. Among these, a methyl group or an ethyl group is preferred because it results in a compound in which aggregation of the colorant in the ink composition is suppressed even under low-temperature and high-temperature conditions, and the compound has high dissolution stability.

[0034] In formula (1), R7 has a structure represented by the following formula (2) or (3): When the compound has these structures, the compound has excellent light resistance and storage stability.

[0035] [ka]

[0036] In formula (2), R8 is -SO3 - group, an alkoxysulfonyl group (-SO3R group), a sulfonamide group (-SON2NRR group), a halogen atom, a perfluoroalkyl group, or a nitro group, and R9 represents a hydrogen atom or a halogen atom.

[0037] In formula (2), the halogen atoms in R8 and R9 are not particularly limited, but include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms. The perfluoroalkyl group in R8 is not particularly limited, but includes trifluoromethyl groups, perfluoroethyl groups, and perfluoropropyl groups.

[0038] In formula (3), R 10 ~R 12 each independently represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group.

[0039] In formula (3), R 10 ~R 12 Examples of the alkyl group in include the same substituents as those exemplified as the alkyl groups in R1 and R2 in the above formula (1).

[0040] In formula (3), R10 ~R 12 In the above, the aryl group having a substituent or the unsubstituted aryl group is not particularly limited, but may be a phenyl group. The substituent of the aryl group is not particularly limited, but may be a methyl group, an ethyl group, a methoxy group, a cyano group, etc.

[0041] In addition, R7 in formula (1) is -SO3 - A structure represented by the following formula (4) in which R9 is a hydrogen atom is more preferred.

[0042] [ka]

[0043] As preferred examples of the compound represented by formula (1), compounds (A1) to (A92) are shown below, but the compound is not limited to the following compounds.

[0044] [ka]

[0045] [ka]

[0046] [ka]

[0047] [ka]

[0048] [ka]

[0049] [ka]

[0050] [ka]

[0051] [ka]

[0052] [ka]

[0053] [ka]

[0054] Among these, compounds (A2), (A3), (A4), (A5), (A6), (A8), (A9), (A10), (A18), (A19), (A22), (A23), (A24), (A25), (A26), (A27), (A28), (A29), (A30), (A31), (A40), (A41), (A42), (A43), (A44) , (A45), (A46), (A47), (A48), (A49), (A59), (A60), (A64), (A65), (A66), (A67), (A68), (A76), (A77), (A78), (A79), (A80), (A83), (A87), (A88), (A89), (A90), and (A91) are preferred.

[0055] Among these, (A2), (A4), (A5), (A6), (A8), (A18), (A19), (A24), (A25), (A26), (A27), (A28), (A40), (A45), (A46), (A64), (A65), (A84), (A88), (A89), (A90), (A91), and (A92) are more preferable.

[0056] In the compound represented by formula (1), the cation is delocalized, and the cationic site may be present at any position in the molecule, and any of these positions is within the scope of the present invention. For example, in the case of compound (A1) having an anionic substituent in the molecule, X in formula (1) - does not exist, and the structure changes as follows:

[0057] [ka]

[0058] On the other hand, in the case of the compound (A74) which does not have an anionic substituent in the molecule, the structure changes as shown below.

[0059] [ka]

[0060] The compound represented by the above general formula (1) may be used alone or in combination of two or more kinds to adjust the color tone, etc., depending on the application. Furthermore, it may be used in combination with a known pigment or dye. The known pigment or dye to be combined may be two or more kinds.

[0061] The oil-based ink composition for writing instruments and the water-based ink composition for writing instruments containing the compound represented by the above general formula (1) can be suitably used in ballpoint pens, felt-tip pens, marking pens, and the like.

[0062] The amount of the compound represented by formula (1) is appropriately selected depending on the application, but is preferably from 1% by mass to 50% by mass, more preferably from 2% by mass to 45% by mass, and even more preferably from 5% by mass to 40% by mass, based on the total amount of the ink composition.

[0063] The compound represented by formula (1) may be used alone as a colorant, but other known colorants may also be used in combination.

[0064] The colorants (dyes, pigments) that can be used in combination are determined according to the purpose and application of the ink, taking into consideration hue, printing sensitivity, light resistance, storage stability, solubility in the resin, and the like.

[0065] The known dyes that can be used in combination are not particularly limited, but examples thereof include 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, and xanthene compounds.

[0066] Specific examples include NIGROSIN BASE EX-BP, NUBIAN BLACKPA-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 (all manufactured by Orient Chemical Industries Co., Ltd.), Aizen Spilon Blue 2BNH, Aizen Spilon Red C-GH, Aizen Spilon Red C-BH, Aizen Spilon Yellow C-GHN new, and Aizen Spilon Yellow GRLH special, Aizen SPT Blue-121 (both manufactured by Hodogaya Chemical Co., Ltd.), etc.

[0067] The blending amount of the dye of the present invention is selected in the range of 1% by mass or more and 50% by mass or less based on the total amount of the ink composition.

[0068] Known pigments that can be used in combination are not particularly limited, but examples thereof include carbon black, aniline black, titanium dioxide pigments, phthalocyanines, quinacridones, diketopyrroles, azos, dioxanes, quinophthalones, triphenylmethanes, perylenes, perinones, metallic pigments, pearl pigments, fluorescent pigments, and phosphorescent pigments.

[0069] Specific examples include FUJI FAST RED 8800 (CI Pigment Red 254) and FUJI FAST RED 2200 (CI Pigment Red 170) (both manufactured by Fuji Pigment Co., Ltd.).

[0070] The pigment preferably has an average particle size of 30 nm or more and 700 nm or less after being dispersed in a medium.

[0071] The pigment may be blended in an amount of from 0.5 to 25% by mass, and preferably from 0.5 to 20% by mass, based on the total amount of the ink composition, as required.

[0072] The colorant, including the compound represented by formula (1) and a dye or pigment that can be used in combination, is appropriately selected depending on the application, but is preferably blended in an amount of 1% by mass or more and 50% by mass or less based on the total amount of the ink composition.

[0073] <Oil-based ink composition for writing instruments> Next, the oil-based ink composition for a writing instrument according to the present invention will be described.

[0074] The oil-based ink composition for writing instruments of the present invention contains, in addition to the colorant containing the compound represented by general formula (1), a medium containing alcohol, and a resin that dissolves in the medium.

[0075] In addition to the above-mentioned components, additives may be added as appropriate within the limits that do not impair the properties in various applications. The additives will be described later.

[0076] [Medium] The "medium" in the present invention is alcohol or glycol ether. The medium is selected according to the purpose and use of the ink, and is not particularly limited, and one or more kinds may be used.

[0077] The alcohols that are preferably used are described below.

[0078] Examples of the alkyl monoalcohol include unsubstituted alkyl monoalcohols such as ethanol, isopropanol, n-butanol, isobutanol, tert-butanol, sec-butanol, 2-methyl-2-butanol, 3-pentanol, octanol, and cyclohexanol; substituted alkyl monoalcohols such as 2-phenoxyethanol and 3-methyl-3-methoxy-1-butanol; and aromatic alcohols such as benzyl alcohol. Examples of the substituent in the substituted alkyl monoalcohol include an alkoxy group and an aryloxy group.

[0079] Further examples include alkyl polyhydric alcohols such as ethylene glycol, diethylene glycol, triethylene glycol, 3-methyl-1,3-butanediol, and 1,3-butanediol.

[0080] Further examples include glycol ether alcohols such as ethylene glycol monobutyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, propylene glycol monomethyl ether, and triethylene glycol monobutyl ether.

[0081] In particular, 3-methyl-3-methoxy-1-butanol, 1,3-butanediol, propylene glycol monomethyl ether, and the like are preferably used.

[0082] Glycol ethers can also be used. Glycol ethers include monoalcohol monoethers, but these are described as alcohols. Diethers are exemplified below. Examples include ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dipropylene glycol, ethylene glycol diethyl ether, diethylene glycol diethyl ether, and diethylene glycol dipropyl ether.

[0083] The medium may contain, in addition to alcohol or glycol ether, water; or an ester solvent such as 3-methyl-3-methoxybutyl acetate, butyl acetate, or methyl propionate.

[0084] The amount of the medium of the present invention used varies depending on the type of writing instrument, such as a ballpoint pen, a felt tip pen, or a marking pen, but is preferably from 1 to 70% by mass, more preferably from 3 to 60% by mass, and particularly preferably from 5 to 30% by mass, based on the total amount of the ink composition.

[0085] [resin] The oil-based ink composition for writing instruments of the present invention contains a resin that dissolves in the above-mentioned medium in order to adjust the viscosity of the ink and improve the scratch resistance.

[0086] The resin is determined depending on the purpose and use of the ink, and is not particularly limited, but examples thereof include 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. These resins may be used alone, or two or more types may be used in combination as necessary.

[0087] In the present invention, butyral resins and ketone resins are preferably used in order to achieve a writing feel that is free of smudges.

[0088] Examples of butyral resins include low polymerization types such as S-LEC BL-1, BL-2, and BL-10, and high polymerization types such as BH-3, BH-6, BX-1, BX-5, and BH-S (all manufactured by Sekisui Chemical Co., Ltd.).

[0089] Examples of ketone resins include Ketone Resin K-90 (manufactured by Arakawa Chemical Industries, Ltd.), Hilac 901, Hilac 110H, and Hilac 111 (all manufactured by Hitachi Chemical Co., Ltd.).

[0090] Moreover, an example of the polyvinylpyrrolidone resin is Polyvinylpyrrolidone K-90 (manufactured by Nippon Shokubai Co., Ltd.).

[0091] The amount of the resin is preferably 1% by mass or more and 50% by mass or less, more preferably 3% by mass or more and 30% by mass or less, and particularly preferably 5% by mass or more and 25% by mass or less, based on the total amount of the ink composition. If it is within the above range, the viscosity can be easily adjusted, the pen tip can be prevented from wearing out, and a stable and good writing feel can be obtained. Furthermore, since the film-forming property can be appropriately suppressed, even if the pen tip is continuously exposed, the ink can be prevented from solidifying, and the "blurring phenomenon" at the start of writing can be suppressed.

[0092] [Additives] Furthermore, if necessary, additives may be added within a range that does not adversely affect the ink, such as rust inhibitors, surfactants, lubricants, wetting agents, UV absorbers, defoamers, antioxidants, pH adjusters, leveling agents, preservatives, and cellulose nanofibers.

[0093] The rust inhibitor is not particularly limited, but examples thereof include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin, ethylenediaminetetraacetic acid, metal salt compounds, and phosphate compounds.

[0094] The surfactant is not particularly limited, but examples thereof include cationic surfactants, anionic surfactants, nonionic surfactants, amphoteric surfactants, silicone-based surfactants, and fluorine-based surfactants.

[0095] The lubricant is not particularly limited, but examples thereof include higher fatty acids, silicone oils, glycerin fatty acid esters, castor oil, phosphoric esters and their metal salts, ammonium salts, etc., and have the effect of preventing wear of the ball receiving seat of the ball tip of a ballpoint pen. These lubricants may be used alone or in combination of two or more kinds. Furthermore, fine particles such as silica fine particles and alumina fine particles may be added to improve lubricity.

[0096] The wetting agent is not particularly limited, but examples thereof include glycerin, sorbitan compounds, polysaccharides, urea, and the like.

[0097] Examples of ultraviolet absorbers include, but are not limited to, 2-(2'-hydroxy-3'-t-butyl-5'-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, and p-benzoic acid-2-hydroxybenzophenone.

[0098] The antifoaming agent is not particularly limited, but examples thereof include silicone-based compounds such as dimethylpolysiloxane, mineral oils, and fluorine-based compounds.

[0099] The antioxidant is not particularly limited, but examples thereof include dibutylhydroxytoluene, nordihydroxytoluene, flavonoids, butylhydroxyanisole, ascorbic acid derivatives, α-tocopherol, and catechins.

[0100] The pH adjuster is not particularly limited, but examples thereof include alkalizing agents such as sodium hydroxide, alkanolamines, oxyethylene alkylamines, polyoxyethylene alkylamines, laurylamine, N,N-dimethylstearinamine, N,N-dimethylstearylamine, N,N-dimethyloctylamine, and ammonium, and acidic compounds such as alkylbenzenesulfonic acid, methanesulfonic acid, dialkylsulfosuccinic acid, naphthalenesulfonic acid, oleic acid, and naphthalenesulfonic acid-formaldehyde condensates.

[0101] The leveling agent is not particularly limited, but examples thereof include acetylene glycol, acetylene alcohol, and silicone surfactants.

[0102] [Manufacturing method] The oil-based ink composition for a writing instrument can be produced by a known method.

[0103] For example, the dispersion can be obtained by blending a medium, a compound represented by general formula (1), a resin, and, if necessary, other colorants and additives at an appropriate temperature range, and stirring and mixing with a mixer, roll, homogenizer, disperser, etc. In addition, a media-type dispersing machine such as a rotary shear homogenizer, a ball mill, a sand mill, an attritor, and a high-pressure counter-collision type dispersing machine can also be used.

[0104] The oil-based ink composition for writing instruments of the present invention must have a certain amount of solids content. If the solids content is reduced, the viscosity of the ink will decrease, leading to ink dripping.

[0105] That is, the viscosity of the oil-based ink composition for a writing instrument of the present invention is 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.

[0106] The oil-based ink composition for writing instruments thus produced is filled into ballpoint pens, felt tip pens, and marking pens.

[0107] For example, a ballpoint pen will be described.

[0108] The structure and shape of the ballpoint pen are not particularly limited. For example, there is a ballpoint pen having a structure in which an ink reservoir, the tip of which is connected to a ball tip with a ball attached to a ball receiving seat at the tip, is housed in the inner space of a barrel, and the tip protrudes from the tip of the barrel. After the oil-based ballpoint pen ink composition is filled from the opening of the ink reservoir through the base end, the opening at the base end is closed with a backflow prevention plug or backflow prevention body.

[0109] As the ball rolls on the writing medium, the ink composition for oil-based ballpoint pens is supplied to the surface of the ball through the gap between the ball tip and the ball, soaking into the writing medium and forming a handwritten mark.

[0110] <Water-based ink composition for writing instruments> Next, the water-based ink composition for a writing instrument according to the present invention will be described.

[0111] The aqueous ink composition for a writing instrument of the present invention is characterized by containing a carrier carrying the general formula (1) dispersed in an aqueous medium.

[0112] [Career] In the present invention, the carrier carrying the general formula (1) means a state in which the compound represented by the general formula (1) is dispersed in the carrier, a state in which the compound represented by the general formula (1) is encapsulated in the carrier, or a state in which the carrier is colored with the compound represented by the general formula (1), etc.

[0113] The carrier is not particularly limited, but examples thereof include binder resins, cellulose nanofibers, and microcapsules.

[0114] The method for producing the resin particles encapsulating the coloring material is not particularly limited, but examples thereof include a bulk resin pulverization method, a suspension polymerization method, an emulsion polymerization method, a mini-emulsion polymerization method, and a phase inversion emulsification method.

[0115] The lump resin crushing method is a method in which a lump resin previously obtained by polymerization so as to contain the compound represented by general formula (1) is physically crushed by using a crusher or the like.

[0116] 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 liquid droplets are polymerized in this state.

[0117] The emulsion polymerization method is a method in which a polymerizable monomer is polymerized in an emulsified state in an aqueous medium in the presence of a compound represented by general formula (1).

[0118] The mini-emulsion polymerization method is a method in which a polymerizable monomer is dissolved or dispersed in a compound represented by the general formula (1), and the resulting solution is vigorously stirred in an aqueous medium in the presence of a surfactant to form resin particles.

[0119] The transfer emulsification method is a method in which the compound represented by general formula (1) and a resin are dissolved in a solvent, and then the mixture is vigorously stirred in an aqueous medium in the presence of a surfactant to form resin particles, and the solvent is then distilled off.

[0120] Examples of methods for bonding the compound represented by general formula (1) to the surface of resin particles prepared in advance include a physical dyeing method in which the compound represented by general formula (1) is attached to the surface of resin particles, and a chemical swelling method in which the resin particles are swelled with an organic solvent and mixed with the compound represented by general formula (1), thereby allowing the compound represented by general formula (1) to penetrate into the interior of the resin.

[0121] Among the above methods, emulsion polymerization, mini-emulsion polymerization, phase inversion emulsification, etc. are preferred from the viewpoint of being able to obtain a resin with a sufficiently small particle size and a high degree of coloration in order to solve the problems of the present invention.

[0122] The aqueous ink composition for writing instruments of the present invention can be obtained by blending a dispersion of a carrier carrying general formula (1) in an aqueous medium, and, if necessary, other colorants and additives, at an appropriate temperature range, and stirring and mixing with a mixer, roll, homogenizer, disperser, etc. It can also be prepared using a media-type disperser such as a rotary shear homogenizer, ball mill, sand mill, attritor, and a high-pressure opposed collision type disperser.

[0123] The aqueous ink composition for writing instruments of the present invention can have a pen tip suitable for a particular application, such as a ballpoint pen tip, a felt tip, a fiber tip, a fiber core, a plastic tip, a porous core, or the like.

[0124] The aqueous ink composition for a writing instrument of the present invention is preferably in a state in which the compound represented by general formula (1) is dispersed in a carrier, or in a state in which the compound represented by general formula (1) is encapsulated in a carrier.

[0125] In order to incorporate such a compound represented by general formula (1) into a carrier, the compound can be produced, for example, by polymerizing the compound represented by general formula (1) using a hydrophobic monomer in which the compound is dissolved, or by polymerizing the compound represented by general formula (1) using a hydrophobic monomer adsorbed on the surface of the compound.

[0126] The content of the compound represented by formula (1) is preferably 0.4 to 20 times the mass ratio of the carrier content. If the content of the compound represented by formula (1) is less than 0.4 times the mass ratio of the resin content, the handwriting tends to have skipped lines or smudges. On the other hand, if the content of the compound represented by formula (1) is more than 20 times the mass ratio of the resin content, aggregation is promoted, and the tip tends to become clogged.

[0127] When an oil-based dye is used as a coloring material, the polymerization can be carried out using a hydrophobic monomer in which the oil-based dye is dissolved. A detailed study of this polymerization method is reported in Colloid and Polymer Science, December 2003, Vol. 282, pp. 119-126. A specific example of a method for polymerization using a hydrophobic monomer adsorbed on the coloring material surface is a method in which a dispersion of a coloring material and a dispersion of a hydrophobic monomer that have been separately prepared are mixed and then polymerized. A detailed study of this method is reported in Macromolecular Chemistry and Physics, January 2001, Vol. 202, pp. 51-60, and this was used as a reference.

[0128] The binder resin of the carrier carrying the general formula (1) in the aqueous medium of the aqueous ink composition for a writing instrument of the present invention is selected depending on the application. For example, a binder resin obtained by copolymerizing a hydrophilic polymerizable monomer such as acrylic acid, methacrylic acid, N-(2-hydroxyethyl)acrylamide, N-vinylpyrrolidone, or a polymerizable monomer having an ammonium salt with a lipophilic polymerizable monomer such as an acrylic acid ester, a methacrylic acid ester, vinyl acetate, styrene, or N-vinylcarbazole in an appropriate mixing ratio by a known method can be used.

[0129] Specifically, homopolymers or copolymers (vinyl resins) of esters having a vinyl group, such as meraryl methacrylate, ethyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, tert-butyl methacrylate, 2-ethylhexyl methacrylate, lauryl methacrylate, stearyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, isobornyl methacrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-methoxyethyl methacrylate, 2-ethoxyethyl methacrylate, dimethylaminoethyl methacrylate, and diethylaminoethyl methacrylate.

[0130] 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 dimethacrylate, and polyfunctional acrylates and methacrylates such as acryloyloxypropyl triacrylate, pentaerythritol trimethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, hexanediol diacrylate, hexanediol dimethacrylate, trimethylolpropane tri(acryloyloxypropyl)ether, tri(acryloyloxyethyl)isocyanurate, tri(acryloyloxyethyl)cyanurate, triallyl isocyanurate, glycerin triacrylate, and glycerin trimethacrylate; and polyfunctional acrylates and methacrylates obtained by adding ethylene oxide or propylene oxide to polyfunctional alcohols such as trimethylolpropane and glycerin, followed by acrylation or methacrylation. Additionally, urethane acrylates, polyester acrylates, and polyfunctional epoxy acrylates or epoxy methacrylates which are reaction products of epoxy resins with acrylic acid or methacrylic acid can also be used.

[0131] Examples of the copolymer include styrene, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, pt-butylstyrene, 4-methoxystyrene, and 4-chlorostyrene. That is, the (meth)acrylic acid ester copolymer is preferably a styrene-(meth)acrylic acid copolymer having a styrene monomer.

[0132] Among the above polymerizable monomers, it is preferable to use cyclohexyl methacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexaacrylate, dipentaerythritol hexamethacrylate, dipentaerythritol pentaacrylate, dipentaerythritol pentamethacrylate, and triallyl isocyanurate. The above polymerizable monomers may be used alone or in combination of two or more as necessary.

[0133] The polyfunctional polymerizable monomer can also be used as a crosslinking agent.

[0134] The polymerization initiator used in the polymerization of the polymerizable monomer in the present invention is an oil-soluble Initiators and / or water-soluble initiators may be used.

[0135] The oil-soluble initiator is not particularly limited, but examples thereof include azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis-2,4-dimethylvaleronitrile, 1,1'-azobis(cyclohexane-1-carbonitrile), and 2,2'-azobis-4-methoxy-2,4-dimethylvaleronitrile; and peroxide initiators such as acetylcyclohexylsulfonyl peroxide, diisopropyl peroxycarbonate, decanonyl 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, and cumene hydroperoxide.

[0136] The water-soluble initiator is not particularly limited, but examples thereof include ammonium persulfate, potassium persulfate, 2,2'-azobis(N,N'-dimethyleneisobutyromidine) hydrochloride, 2,2'-azobis(2-aminodinopropane) hydrochloride, azobis(isobutylamidine) hydrochloride, 2,2'-azobisisobutyronitrile sodium sulfonate, ferrous sulfate, and hydrogen peroxide.

[0137] The concentration of the polymerization initiator is preferably from 0.01% by mass to 10% by mass, and more preferably from 0.03% by mass to 5% by mass, based on the total mass of the monomer components including the hydrophobic monomer.

[0138] The emulsifier used in the polymerization of the polymerizable monomer used in the present invention is not particularly limited, and may be a cationic surfactant, an anionic surfactant, a nonionic surfactant, or the like.

[0139] Specific examples of the cationic surfactant include dodecyl ammonium chloride, dodecyl ammonium bromide, dodecyl trimethyl ammonium bromide, dodecyl pyridinium chloride, dodecyl pyridinium bromide, and hexadecyl trimethyl ammonium bromide.

[0140] Examples of anionic surfactants include fatty acid soaps such as sodium stearate and sodium dodecanoate, sodium dodecyl sulfate, sodium dodecylbenzenesulfonate, and sodium lauryl sulfate.

[0141] Further, examples of nonionic surfactants include dodecyl polyoxyethylene ether, hexadecyl polyoxyethylene ether, nonylphenyl polyoxyethylene ether, lauryl polyoxyethylene ether, sorbitan monooleate polyoxyethylene ether, monodecanoyl sucrose, and lauric acid monoglyceride (manufactured by Taiyo Kagaku Co., Ltd.).

[0142] The content of the binder resin in the carrier is preferably 5% by mass or more and 50% by mass or less, more preferably 10% by mass or more and 40% by mass or less, based on the mass (total solid content) of the aqueous ink composition for writing instruments according to the present invention. By making the content 5% by mass or more and 50% by mass or less, the sensitivity to light exposure and the strength of the drawing paper can be further improved, and the adhesiveness of the aqueous ink composition for writing instruments is also improved.

[0143] The binder resin of the carrier of the present invention may contain a photopolymerization initiator. Examples of the photopolymerization initiator include vicinal polyketo aldonyl compounds, α-carbonyl compounds, acionoin ethers, polyquinone compounds, combinations of triaryl imidazole dimers and p-aminophenyl ketones, trioxadiazole compounds, etc. Among these, 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butanone (trade name: Irgacure 369, manufactured by BASF) is preferred.

[0144] The binder resin of the carrier of the present invention may contain a photoacid generator as required. As the photoacid generator, known photoacid generators such as salts of onium ions, such as sulfonium, iodonium, selenium, ammonium, and phosphonium, and anions can be used.

[0145] Examples of the sulfonium ion include triphenylsulfonium, tri-p-tolylsulfonium, tri-o-tolylsulfonium, tris(4-methoxyphenyl)sulfonium, 1-naphthyldiphenylsulfonium, diphenylphenacylsulfonium, phenylmethylbenzylsulfonium, 4-hydroxyphenylmethylbenzylsulfonium, dimethylphenacylsulfonium, and phenacyltetrahydrothiophenium.

[0146] Examples of the iodonium ion include diphenyliodonium, di-p-tolyliodonium, bis(4-dodecylphenyl)iodonium, bis(4-methoxyphenyl)iodonium, and (4-octyloxyphenyl)phenyliodonium.

[0147] Examples of the selenium ion include triarylselenium ions 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.

[0148] Examples of the ammonium ion include tetraalkylammonium ions such as tetramethylammonium, ethyltrimethylammonium, diethyldimethylammonium, triethylmethylammonium, tetraethylammonium, trimethyl-n-propylammonium, trimethylisopropylammonium, trimethyl-n-butylammonium, and trimethylisobutylammonium.

[0149] Examples of the phosphonium ion include tetraphenylphosphonium, tetra-p-tolylphosphonium, tetrakis(2-methoxyphenyl)phosphonium, triphenylbenzylphosphonium, triphenylphenacylphosphonium, triphenylmethylphosphonium, triethylbenzylphosphonium, and tetraethylphosphonium.

[0150] The anion is ClO4 - , BrO4 - Perhalogen acid ions such as FSO3 - , ClSO3 - Halogenated sulfonate ions such as CH3SO4 - , CF3SO4 - , HSO4 - Sulfate ions such as HCO3 - , CH3CO3 - Carbonate ions such as AlCl4 - , AlF4 - aluminate ion, etc.; hexafluorobismuthate ion, CH3COO - , CF3COO - , C6H5COO - , CH3C6H4COO - , C6F5COO - , CF3C6H4COO - Carboxylic acid ions such as B(C6H5)4 - , CH3CH2CH2CH2B(C6H5)3 - aryl borate ions such as aryl borates; thiocyanate ions, and nitrate ions, but are not limited to these.

[0151] The cellulose nanofibers of the carrier carrying general formula (1) in the aqueous medium of the aqueous ink composition for a writing instrument of the present invention are selected according to the application, but are, for example, obtained by subjecting plant fibers to a chemical and / or mechanical fiber defibration treatment, and are ultrafine fibers having an average width of about several nm to 20 nm and an average length of about 0.5 μm to several μm.

[0152] Materials containing cellulose fibers that can be used include plants such as wood, bamboo, kenaf, hemp, jute, wood pulp, waste paper, crystalline cellulose, agricultural waste, and recycled pulp, animals such as sea squirts, algae, and microorganisms.

[0153] Examples of devices for performing the fiberization process include a rotary shear type homogenizer, a high-pressure homogenizer, a high-pressure homogenizer, a ball mill, a sand mill, an attritor, a high-pressure opposed collision type disperser, a grinder, and a conical refiner.

[0154] Cellulose nanofibers are commercially available and can be used. Examples of commercially available products include Rheocrysta I-2AX, CNF 03, and CNF 04 (manufactured by Daiichi Chemical Industry Co., Ltd.), ELLEX-S (manufactured by Daio Paper Co., Ltd.), and nanoforest-S (manufactured by Chuetsu Pulp Industry Co., Ltd.).

[0155] The size (fiber diameter) of these cellulose nanofibers varies depending on the type of cellulose nanofiber. In addition, a fiber diameter is selected that is in a suitable range in terms of thickening effect, stability over time, color development, etc., within a range that does not impair the characteristics in various applications.

[0156] The amount of cellulose nanofibers is preferably 0.001 parts by mass or more and 40 parts by mass or less, more preferably 0.01 parts by mass or more and 10 parts by mass or less, and even more preferably 0.05 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the aqueous medium contained in the aqueous ink composition for writing instruments.

[0157] In the aqueous ink composition for writing instruments, the aqueous medium in which the compound represented by general formula (1) is dispersed can be water or a mixture of water and a water-soluble organic solvent.

[0158] There are no particular limitations on the method for dyeing cellulose nanofibers with the compound represented by general formula (1). For example, cellulose nanofibers are contacted with the compound represented by general formula (1) in an aqueous medium, and then heated or oxidized as necessary, and the medium is then distilled off to obtain dyed cellulose nanofibers. A pH adjuster, a developer, a dispersant, etc. may be added during contact.

[0159] The aqueous coloring liquid may be the same system used when dyeing the cellulose nanofibers, or may be a liquid obtained by extracting the colored cellulose nanofibers after drying and dispersing them again in an aqueous medium or the like.

[0160] [Medium] When preparing 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. As the water-soluble organic solvent to be contained in the aqueous medium, for example, alcohol, polyhydric alcohol, polyglycol, glycol ether, nitrogen-containing polar solvent, sulfur-containing polar solvent, etc. can be used. 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 ink for writing instruments, improving the solubility of coloring materials, and effectively penetrating the ink for writing instruments into recording paper. In the aqueous medium in the ink for writing instruments, the ratio of water to the water-soluble organic solvent (based on mass) 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. In this way, the dispersibility or solubility of the colorant containing the compound represented by general formula (1) in the ink can be improved.

[0161] The aqueous ink composition for writing instruments can be suitably used in aqueous ballpoint pens, gel inks, inks for aqueous ballpoint pens, felt tip pens, marking pens, etc., and additives such as dispersants, lubricants, pH adjusters, rust inhibitors, preservatives, or antibacterial agents may be added as appropriate within the range that does not impair the properties in various applications. The additives will be described later.

[0162] [Additives] The lubricant is not particularly limited, but examples thereof include nonionic lubricants such as fatty acid esters of polyhydric alcohols, higher fatty acid esters of sugars, and alkyl phosphate esters; anionic lubricants such as alkyl sulfonates and alkyl aryl sulfonates of higher fatty acid amides; derivatives of polyalkylene glycols, fluorine-based surfactants, and polyether-modified silicones.

[0163] The pH adjuster is not particularly limited, but examples thereof include sodium hydroxide, urea, monoethanolamine, diethanolamine, triethanolamine, sodium tripolyphosphate, sodium carbonate, alkali metal salts of phosphoric acid, etc. For example, from the viewpoints of usability, safety, and stability of the ink itself, the pH is preferably adjusted to 4 to 11, and more preferably 5 to 10.

[0164] The rust inhibitor is not particularly limited, but examples thereof include benzotriazole, tolyltriazole, dicyclohexylammonium nitrite, diisopropylammonium nitrite, saponin, and phosphate compounds.

[0165] The preservative or antibacterial agent is not particularly limited, but examples thereof include phenol, sodium benzoate, benzimidazole compounds, sodium omadine, sodium pentachlorophenol, sodium sorbate, 1,2-benzisothiazolin-3-one, and the like.

[0166] [Manufacturing method] The aqueous ink composition for a writing instrument can be produced by a known method.

[0167] For example, the aqueous ink composition for writing instruments of the present invention and, if necessary, other colorants and additives are blended at an appropriate temperature range, and the resulting mixture is stirred and mixed using a mixer, roll, homogenizer, disperser, etc. Alternatively, a media-type dispersing machine such as a rotary shear homogenizer, ball mill, sand mill, or attritor, and a high-pressure opposed collision type dispersing machine can also be used.

[0168] The water-based ink composition for writing instruments may contain other pigments, water-soluble solvents, and the like.

[0169] The pigment that can be used in combination is not particularly limited, but can be selected from inorganic and organic pigments that have been conventionally used for writing instruments such as water-based ballpoint pens.

[0170] Examples of inorganic pigments include carbon black and metal powder.

[0171] Examples of organic pigments include azo pigments, phthalocyanine pigments, perylene pigments, quinacridone pigments, etc. The content is from 0.1 to 50 parts by mass, preferably from 0.5 to 30 parts by mass, per 100 parts by mass of the aqueous medium.

[0172] When a pigment is used in combination, it is preferable to use a dispersant. As the dispersant, an ionic surfactant, a nonionic surfactant, a polymer surfactant, a water-soluble resin, or the like is used within a range that does not impair the characteristics in the application.

[0173] The oil-based ink composition for writing instruments thus produced is filled into ballpoint pens, felt tip pens, and marking pens. EXAMPLES

[0174] The present invention will be described in more detail below 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.

[0175] The compound represented by the general formula (1) is synthesized by a known method and identified as follows: 1 H nuclear magnetic resonance spectroscopy ( 1 H-NMR spectrometer (ECA-400, manufactured by JEOL Ltd.) and LC / TOF MS spectrometer (LC / MSD TOF, manufactured by Agilent Technologies).

[0176] <Production of Oil-Based Ink Composition for Writing Instruments> [Examples 1 to 22 and Comparative Examples 1 to 13] The constituent materials shown in Tables 1-1 and 1-2 were used. The compounds of general formula (1) are the compounds (A1) to (A92) listed above. First, a resin was added to a medium, which was then heated to 70°C to dissolve, and then cooled to room temperature. A colorant and other constituent materials were added, and the mixture was dispersed for 3 hours using an attritor (manufactured by Mitsui Mining Co., Ltd.) to produce an oil-based ink composition for writing instruments.

[0177] The comparative colorant compounds (B1) to (B4) in Table 1-2 are the following compounds.

[0178] [ka]

[0179] [Table 1-1]

[0180] [Table 1-2]

[0181] [Dissolution stability evaluation] 20 mL of each of the oil-based ink compositions for writing instruments obtained above was added to a 50 mL sample bottle, which was then sealed and left for one 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 Corporation). The fewer aggregates there were, the better the dissolution stability was judged to be. A: The ink composition is good and free of agglomerates. B: A small amount of agglomeration occurred in the ink composition. C: Coagulation occurred in the ink composition.

[0182] [Evaluation of blurring (initial writing quality) at the beginning of writing] Each of the oil-based ink compositions for writing instruments obtained above was filled into an ink reservoir made of polypropylene tube having an inner diameter of 1.2 mm and a length of 140 mm. A ballpoint pen for evaluation test was prepared by combining this ink reservoir and a phosphor bronze tip (ball diameter: 0.7 mm).

[0183] The cap was removed from the test ballpoint pen, and the pen was left to stand for 1 hour under low temperature (0°C) and high temperature (60°C) conditions with a humidity of 65%, after which a circle was handwritten on the pen using JIS P3201 writing paper.

[0184] The smearing at the beginning of writing was evaluated according to the following criteria. The less smearing occurred, the better the initial writing performance was judged to be. A: No smearing occurred under either low temperature (0°C) or high temperature (60°C) conditions. B: Blurring occurred under either the low temperature (0℃) or high temperature (60℃) conditions. C: Conspicuous smearing occurred under either the low temperature (0°C) or high temperature (60°C) conditions.

[0185] [Writing experience evaluation] Following the evaluation of initial writing performance, we evaluated the writing feel. The writing feel was evaluated based on the following criteria: whether the handwriting continues to be stable without skipping or smearing, and there is no change in the writing density. The writing feel was judged to be good if the handwriting continues to be stable without skipping or smearing, and there is no change in the writing density. A: At both low (0°C) and high (60°C) temperatures, there was no skipping or smearing of lines in the writing, and there was no change in the writing density. B: Under at least one of the low temperature (0°C) and high temperature (60°C) conditions, slight skipping or smearing of lines in the handwriting occurred, or slight change in handwriting density occurred. C: At least one of the low temperature (0℃) and high temperature (60℃) conditions caused skipping and blurring of lines in the handwriting, and changes in the handwriting density occurred.

[0186] [Handwriting robustness evaluation] The handwriting fastness was evaluated. For the handwriting fastness evaluation, the ballpoint pen was used to write at a constant pressure over a distance of 20 cm to create a sample. The sample was placed in a xenon test device (Atlas Weather-O-Meter Ci4000, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and measured (illuminance: 0.28 W / m at 340 nm). 2 The sample was exposed for 10 hours under the conditions of black panel temperature: 40°C, relative humidity: 50%). The spectra before and after exposure were read with a scanner, and the initial optical density was defined as OD0, and the OD after 5 hours of exposure was defined as OD5. The OD residual rate was defined as follows: OD residual rate (%)=(OD5 / OD0)×100

[0187] The evaluation criteria are as follows: A: When the OD residual rate (%) is 85 or less, the handwriting fastness is very sufficient. B: 70≦OD residual rate (%)<85, and handwriting fastness is sufficient. C: OD residual rate (%) is <70, and writing fastness is insufficient.

[0188] The results of the above evaluations are shown in Table 2.

[0189] [Table 2]

[0190] From the above, the oil-based ink composition for writing instruments of the present invention, compared to the comparative oil-based ink composition, has high dissolution stability and suppresses aggregation of the colorant within the ink composition even under low and high temperature conditions, and by using this oil-based ink composition for writing instruments, it is possible to provide a ballpoint pen that suppresses the smearing phenomenon at the start of writing, has a good writing feel without skipped lines or smearing in the handwriting, and has high handwriting fastness.

[0191] <Production of Water-Based Ink Composition for Writing Instruments> Example 23 5 parts of compound A-2, 1 part of methanol, and 0.5 parts of cellulose nanofiber (Leocrysta I-2AX) were added, and then 99 parts of ion-exchanged water was added. The internal temperature was heated to 80°C, and the mixture was stirred for 2 hours while removing methanol. After cooling to room temperature, the mixture was dispersed with a homogenizer for 5 minutes to prepare an aqueous ink composition (23) for writing instruments containing cellulose nanofiber dyed with compound A-2.

[0192] [Examples 24 to 42, Comparative Examples 14 to 27] Water-based ink compositions for writing instruments (24) to (42) containing cellulose nanofibers dyed with compounds and comparative water-based ink compositions for writing instruments (14) to (27) were prepared in the same manner as in Example 23, except that the compounds and cellulose nanofibers were changed to those shown in Table 3. Note that cellulose nanofibers are available from Rheocrysta 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.).

[0193] The comparative compounds (B1) to (B4) are the same as above.

[0194] [Table 3]

[0195] Example 43 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 resulting mixture was added dropwise to 70g of an aqueous solution (concentration 0.3%) of 0.05g of lauric acid monoglyceride (manufactured by Taiyo Kagaku Co., Ltd.), and stirred at 300 rpm for 1 hour. The mixture was dispersed with a homogenizer for 1 hour (Dispersion A).

[0196] 10 g of compound (A-2) was added to 110 g of an aqueous solution of lauric acid monoglyceride (concentration: 2.7%), and the mixture was stirred at 300 rpm for 2 hours, and then dispersed with a homogenizer for 1 hour (dispersion liquid B).

[0197] 20 g of dispersion A and 80 g of dispersion B were mixed and stirred at 300 rpm for 1 hour. Then, the mixture was dispersed with a homogenizer for 5 minutes and stirred for 1 hour. After further dispersing with a homogenizer for 5 minutes, the mixture was polymerized at 70°C for 8 hours under a nitrogen atmosphere. This was filtered with a 5.0 μm filter to obtain an aqueous ink composition for writing instruments (43). The average particle size of the resin particles in the obtained aqueous ink composition for writing instruments was 58 nm.

[0198] [Examples 44 to 48, Comparative Examples 28 to 32] Water-based ink compositions for writing instruments (44) to (48) in which the compound represented by general formula (1) is dispersed or encapsulated in a carrier, and comparative water-based ink compositions for writing instruments (28) to (32) were prepared in the same manner as in Example 43, except that the materials used were changed to those shown in Table 4. Note that in all of Comparative Examples 28 to 32, polymerization inhibition occurred, and it was not possible to prepare water-based ink compositions for writing instruments, and evaluation was not possible.

[0199] [Table 4]

[0200] [Dissolution stability evaluation] 20 mL of each of the aqueous ink compositions for writing instruments obtained above was added to a 50 mL sample bottle, which was then sealed and left for one 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 Corporation). The fewer the aggregates, the better the dispersion stability in the aqueous medium was judged to be. A: The ink composition is good and free of agglomerates. B: A small amount of agglomeration occurred in the ink composition. C: Coagulation occurred in the ink composition.

[0201] [Evaluation of blurring (initial writing) at the beginning of writing] Each of the water-based ink compositions for writing instruments obtained above was filled into an ink reservoir made of polypropylene tube having an inner diameter of 1.2 mm and a length of 140 mm. A ballpoint pen for evaluation test was prepared by combining this ink reservoir and a phosphor bronze tip (ball diameter: 0.7 mm).

[0202] The cap was removed from the test ballpoint pen, and the pen was left to stand for 1 hour under low temperature (0°C) and high temperature (60°C) conditions with a humidity of 65%, after which a circle was handwritten on the pen using JIS P3201 writing paper.

[0203] The smearing at the beginning of writing was evaluated according to the following criteria. The less smearing occurred, the better the initial writing performance was judged to be. A: No smearing occurred under either low temperature (0°C) or high temperature (60°C) conditions. B: Blurring occurred under either the low temperature (0℃) or high temperature (60℃) conditions. C: Conspicuous smearing occurred under either the low temperature (0°C) or high temperature (60°C) conditions.

[0204] [Writing experience evaluation] Following the evaluation of initial writing performance, we evaluated the writing feel. The writing feel was evaluated based on the following criteria: whether the handwriting continues to be stable without skipping or smearing, and there is no change in the writing density. The writing feel was judged to be good if the handwriting continues to be stable without skipping or smearing, and there is no change in the writing density. A: At both low (0°C) and high (60°C) temperatures, there was no skipping or smearing of lines in the writing, and there was no change in the writing density. B: Under at least one of the low temperature (0°C) and high temperature (60°C) conditions, slight skipping or smearing of lines in the handwriting occurred, or slight change in handwriting density occurred. C: At least one of the low temperature (0℃) and high temperature (60℃) conditions caused skipping and blurring of lines in the handwriting, and changes in the handwriting density occurred.

[0205] [Handwriting robustness evaluation] The handwriting fastness was evaluated. For the handwriting fastness evaluation, the ballpoint pen was used to write at a distance of 20 cm with a constant writing pressure to create a sample. The sample was placed in a xenon test device (Atlas Weather-O-Meter Ci4000, manufactured by Toyo Seiki Seisakusho Co., Ltd.) and measured (illuminance: 0.28 W / m at 340 nm). 2 The sample was exposed for 10 hours under the conditions of black panel temperature: 40°C, relative humidity: 50%). The spectra before and after exposure were read with a scanner, and the initial optical density was defined as OD0, and the OD after 5 hours of exposure was defined as OD5. The OD residual rate was defined as follows: OD residual rate (%)=(OD5 / OD0)×100

[0206] The evaluation criteria are as follows: A: When the OD residual rate (%) is 85 or less, the handwriting fastness is very sufficient. B: 70≦OD residual rate (%)<85, and handwriting fastness is sufficient. C: OD residual rate (%) is <70, and writing fastness is insufficient.

[0207] The results of the above evaluations are shown in Tables 5 and 6.

[0208] [Table 5]

[0209] [Table 6]

[0210] From the above, the aqueous ink composition for writing instruments of the present invention has a higher dispersion stability in an aqueous medium of the carrier carrying general formula (1) than the comparative ink composition. In other words, this indicates that when the carrier is prepared by polymerization, polymerization inhibition with general formula (1) does not occur, and when cellulose nanofibers are used, compatibility with general formula (1) is high. In addition, by using the aqueous ink composition for writing instruments of the present invention, it is possible to provide a ballpoint pen that suppresses the phenomenon of smearing at the start of writing, has a good writing feel without skipping or smearing in the handwriting, and has high handwriting fastness. [Industrial Applicability]

[0211] The oil-based ink composition for writing instruments of the present invention has high dissolution stability because the aggregation of the colorant in the ink composition is suppressed even under low and high temperature conditions. Furthermore, by using the oil-based ink composition for writing instruments, it is possible to provide ballpoint pens, felt-tip pens, marking pens, etc. that suppress the phenomenon of smearing at the start of writing, have a good writing feel without line skipping or smearing in the handwriting (the handwriting density does not change and the handwriting continues to be stably produced) and have high handwriting fastness, with the phenomenon of smearing at the start of writing being suppressed.

[0212] In addition, the aqueous ink composition for writing instruments of the present invention has high dispersion stability in an aqueous medium of the carrier carrying the general formula (1). Furthermore, by using the aqueous ink composition for writing instruments, it is possible to provide ballpoint pens, felt-tip pens, marking pens, and the like that suppress the phenomenon of smearing at the beginning of writing, provide a good writing feel without line skipping or smearing in the handwriting (the handwriting density does not change and the handwriting continues to be stably produced) and have high handwriting fastness, with no blurring or smearing occurring at the beginning of writing.

Claims

1. a medium containing an alcohol or a glycol ether; a resin that is soluble in said medium; and A colorant containing a compound represented by the following general formula (1): 【Chemistry 1】 [In formula (1), R 1 and R 2 each independently represents a substituted or unsubstituted phenyl group; R 3 and R 4 each independently represents an alkyl group having a substituent having from 2 to 12 carbon atoms or an unsubstituted alkyl group, a cyano group, a trifluoromethyl group, or a halogen atom; R 5 and R 6 each independently represents a hydrogen atom or an alkyl group; R 7 represents a structure represented by the following formula (2) or (3): 【Chemistry 2】 In formula (2), R 8 is -SO 3 - R represents a group, an alkoxysulfonyl group, a sulfonamide group, a halogen atom, a perfluoroalkyl group, or a nitro group; 9 represents a hydrogen atom or a halogen atom, In formula (3), R 10 ~R 12 each independently represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, X - represents an anion and may be absent when there is at least one anionic substituent in the molecule.

1. An oil-based ink composition for a writing instrument, comprising:

2. In the general formula (1), R 1 and R 2 2. The oil-based ink composition for writing instruments according to claim 1, wherein and are phenyl groups having the same substituent or unsubstituted phenyl groups.

3. 3. The oil-based ink composition for a writing instrument according to claim 1, wherein the formula (2) is a structure represented by the following formula (4): 【Chemistry 3】

4. 4. The oil-based ink composition for a writing instrument according to claim 1, wherein the resin comprises at least one resin selected from the group consisting of butyral resins and ketone resins.

5. A ballpoint pen using the oil-based ink composition for writing instruments according to any one of claims 1 to 4.

6. 1. An aqueous ink composition for a writing instrument, comprising a carrier carrying a compound represented by the following general formula (1) dispersed in an aqueous medium: 【Chemistry 4】 [In formula (1), R 1 and R 2 each independently represents a substituted or unsubstituted phenyl group; R 3 and R 4 each independently represents an alkyl group having a substituent having from 2 to 12 carbon atoms or an unsubstituted alkyl group, a cyano group, a trifluoromethyl group, or a halogen atom; R 5 and R 6 each independently represents a hydrogen atom or an alkyl group; R 7 represents a structure represented by the following formula (2) or (3): 【Chemistry 5】 In formula (2), R 8 is -SO 3 - R represents a group, an alkoxysulfonyl group, a sulfonamide group, a halogen atom, a perfluoroalkyl group, or a nitro group; 9 represents a hydrogen atom or a halogen atom, In formula (3), R 10 ~R 12 each independently represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, X - represents an anion and may be absent when there is at least one anionic substituent in the molecule.

7. In the general formula (1), R 1 and R 2 7. The aqueous ink composition for writing instruments according to claim 6, wherein and are phenyl groups having the same substituent or unsubstituted phenyl groups.

8. The aqueous ink composition for a writing instrument according to claim 6 or 7, wherein the formula (2) is a structure represented by the following formula (4): 【Chemistry 6】

9. The aqueous ink composition for a writing instrument according to any one of claims 6 to 8, wherein the carrier is a binder resin or a cellulose nanofiber.

10. A ballpoint pen using the aqueous ink composition for writing instruments according to any one of claims 6 to 9.

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