JP2018193531A - Aqueous ink composition for writing instruments - Google Patents

Abstract

To provide an aqueous ink composition for writing instruments that is suitable for writing instruments such as a felt-tip pen, marking pen, ballpoint, which prevents temporal discoloration and aggregation and has temporal stability, and an aqueous ink composition for writing instruments prepared therewith.SOLUTION: An aqueous ink composition for writing instruments at least contains: at least one monomer selected from the following A group; a dispersion liquid of colored resin fine particles for aqueous ink, in which colored resin fine particles containing a basic dye or oil-soluble dye are dispersed in water; and at least one antioxidant selected from the following B group. A group: phthalate-2-methacryloyloxyester, phthalate-2-acryloyloxyester, hexahydrophthalic acid-2-methacryloyloxyethyl, hexahydrophthalic acid-2-acryloyloxyethyl, 2-acryloyloxyethyl-2-hydroxyethyl-phthalate, 2-methryloyloxyethyl-2-hydroxyethyl-phthalate. B group: polyphenol, cysteine, ascorbic acid, polyvinyl pyrrolidone oligomer, butylhydroxyanisol.SELECTED DRAWING: None

Description

  The present invention relates to an aqueous ink composition for a writing instrument suitable for a writing instrument such as a sign pen, a marking pen, and a ballpoint pen using a dispersion of colored resin fine particles for aqueous ink.

  Conventionally, it is known that a resin emulsion having a specific polymer structure is dyed with a dye and used as a coloring material called a pseudo pigment.

  For example, 1) An aqueous dispersion of colored resin fine particles for aqueous ink prepared by emulsion polymerization of a vinyl monomer having an acidic functional group in which a water-soluble basic dye is dissolved in the presence of a polymerizable surfactant (for example, patents) 2) At least a carboxyl group-containing vinyl monomer (A) having an acid functional group solubility in water of 10% by mass or less, acrylic acid or methacrylic acid, and a linear or cyclic alcohol having 2 to 18 carbon atoms Aqueous ink composition for writing instruments using a dispersion of colored resin fine particles for aqueous ink in which colored resin fine particles composed of an ester monomer (B) and a basic dye or an oil-soluble dye are dispersed in water ( For example, see Patent Document 2).

  However, the water-based ink for writing instruments using the dispersion liquid of colored resin fine particles for water-based ink as a coloring material may cause discoloration or agglomeration over time when the pH is set in an alkaline region or the like. There were issues such as. It is inferred that this is because the acidic component is liberated due to hydrolysis of the polymer component having an ester group, resulting from chemical interaction between the acidic component and the dye component.

JP-A-10-259337 (Claims, Examples, etc.) JP-A-2006-196623 (Claims, Examples, etc.)

  The present invention has been made in view of the above-described problems of the prior art, and is intended to solve this problem. In the water-based ink for writing instruments using the dispersion liquid of colored resin fine particles for water-based ink as a coloring material, the pH is in an alkaline region or the like. It is an object of the present invention to provide an aqueous ink composition for a writing instrument suitable for writing instruments such as sign pens, marking pens, and ballpoint pens, which are excellent in stability over time, without causing discoloration or aggregation with time. And

  As a result of intensive studies in view of the above-described conventional problems, the present inventor has found that water-based colored resin fine particles composed of at least a specific monomer and a basic dye or an oil-soluble dye are dispersed in water. The inventors have found that a water-based ink composition for a writing instrument can be obtained by containing a dispersion of colored resin fine particles for ink and a specific antioxidant, and has completed the present invention.

That is, the water-based ink composition for a writing instrument according to the present invention has at least one colored resin fine particle composed of at least one monomer selected from the following group A and a basic dye or oil-soluble dye dispersed in water. And a dispersion of colored resin fine particles for water-based ink and at least one antioxidant selected from Group B below.
Group A:
Phthalic acid-2-methacryloyloxyester, phthalic acid-2-acryloyloxyester, hexahydrophthalic acid-2-methacryloyloxyethyl, hexahydrophthalic acid-2-acryloyloxyethyl, 2-acryloyloxyethyl-2-hydroxy Ethyl-phthalic acid, 2-methacryloyloxyethyl-2-hydroxyethyl-phthalic acid Group B:
Polyphenols, cysteines, ascorbic acids, oligomers of polyvinylpyrrolidone, butylhydroxyanisole At least one antioxidant selected from group B is chlorogenic acid, caffeic acid, tannic acid, L-ascorbic acid, piceatannol Resveratrol is preferred.
The writing instrument of the present invention is characterized by mounting the above-described aqueous ink composition for a writing instrument.

  According to the present invention, a water-based ink composition for a writing instrument suitable for writing instruments such as a sign pen, a marking pen, a ballpoint pen, etc., which does not cause discoloration or aggregation over time and has excellent stability over time. A writing instrument equipped with this is provided.

Hereinafter, embodiments of the present invention will be described in detail.
The aqueous ink composition for a writing instrument of the present invention is an aqueous solution in which colored resin fine particles composed of at least one monomer selected from the following group A and a basic dye or an oil-soluble dye are dispersed in water. It contains a dispersion of colored resin fine particles for ink and at least one antioxidant selected from the following group B.
Group A:
Phthalic acid-2-methacryloyloxyester, phthalic acid-2-acryloyloxyester, hexahydrophthalic acid-2-methacryloyloxyethyl, hexahydrophthalic acid-2-acryloyloxyethyl, 2-acryloyloxyethyl-2-hydroxy Ethyl-phthalic acid, 2-methacryloyloxyethyl-2-hydroxyethyl-phthalic acid Group B:
Polyphenols, cysteines, ascorbic acids, polyvinylpyrrolidone oligomers, butylhydroxyanisole

  The dispersion of colored resin fine particles for water-based ink used in the present invention is a dispersion of colored resin fine particles composed of at least one monomer selected from Group A and a basic dye or oil-soluble dye in water. It is what has been.

  Phthalic acid-2-methacryloyloxy ester, phthalic acid-2-acryloyloxy ester, hexahydrophthalic acid-2-methacryloyloxyethyl, hexahydrophthalic acid-2-acryloyloxyethyl listed in the above group A used in the present invention, 2-acryloyloxyethyl-2-hydroxyethyl-phthalic acid and 2-methacryloyloxyethyl-2-hydroxyethyl-phthalic acid are coloring monomers and are at least one of these (each alone or in two). By using the monomer of the above mixture), colored resin fine particles having excellent color developability can be obtained.

In the present invention, in addition to the above monomer, a hydrophobic vinyl monomer can be preferably used from the viewpoint of obtaining colored resin fine particles having a deep color and excellent color developability.
The hydrophobic vinyl monomer is not particularly limited, and for example, at least one monomer such as esters of acrylic acid or methacrylic acid, styrenes such as styrene and methylstyrene can be used.
Examples of esters of acrylic acid or methacrylic acid that can be used include ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, (meth) Isobutyl acrylate, t-butyl (meth) acrylate, hexyl (meth) acrylate, cyclohexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, There may be mentioned at least one of palmityl (meth) acrylate, stearyl (meth) acrylate, behenyl (meth) acrylate, isobornyl (meth) acrylate, and the like. In addition, the notation of “(meth) acrylic acid” represents “acrylic acid and / or methacrylic acid”.

  Examples of the basic dye used in the present invention include di- and triarylmethane-based dyes; azine-based (including nigrosine), oxazine-based and thiazine-based quinoneimine-based dyes; xanthene-based dyes; triazole azo-based dyes; Benzothiazole azo dyes; azo dyes; methine dyes such as polymethine, azomethine, and azamethine dyes; anthraquinone dyes; and basic dyes such as phthalocyanine dyes. Water-soluble basic dyes are desirable.

Specific basic dyes that can be used include C.I. I. Basic yellow (-1, -2, -9, -40, -80, etc.), C.I. I. Basic orange (-1, -2, -7, -34, etc.), C.I. I. Basic red (-1, -1: 1, -2, -3, -53, etc.), C.I. I. Basic violet (-1, -2, -3, -39, etc.), C.I. I. Basic blue (-1, -2, -5, -7, -88, etc.), C.I. I. Basic green (-1, -4, -6, -10 etc.), C.I. I. Basic brown (-1, -2, -4, -15 etc.), C.I. I. Each No. described in the COLOR INDEX such as basic black (-1, -2, -7, -8, etc.). The dye of each color is mentioned.
Moreover, these commercially available products can also be used. For yellow basic dyes, AIZEN CATILON YELLOW GPLH (trade name manufactured by Hodogaya Chemical Co., Ltd.) and the like, for red basic dyes, AIZEN CATILON RED BLH, AIZEN CATILON RED Blue basic dyes such as RH (trade name, manufactured by Hodogaya Chemical Co., Ltd.), Diacryl Supra Brilliant Red 2G (trade name, manufactured by Mitsubishi Chemical Corporation), Sumicryl Red B (trade name, manufactured by Sumitomo Chemical Co., Ltd.), etc. In the case of green basic dyes such as AIZEN CATILON TURQUOISE BLUE LH (trade name manufactured by Hodogaya Chemical Co., Ltd.), Diacyl Super Brilliant Green 2GL (trade name manufactured by Mitsubishi Chemical Corporation), etc. Janus Brown R (Nippon Chemical Co., Ltd. under the trade name), AIZEN CATHILON BROWN GH (Hodogaya Chemical Co., Ltd. under the trade name), and the like.

Examples of the oil-soluble dye used in the present invention include commercially available monoazo, disazo, metal complex salt type monoazo, anthraquinone, phthalocyanine, and triarylmethane. Further, a salt-forming oil-soluble dye in which a functional group such as an acid / basic dye is substituted with a hydrophobic group can also be used.
Examples of yellow type include C.I. I. Solvent Yellow 16, 29, 30, 56, 79, 82, 114, 116; I. Solvent Orange 67; I. Solvent Red 1, 8, 25, 27, 49, 122, 127, 132, 146, 218; I. Solvent Blue 5, 36, 38, 44, 63, 70, 83, 105, 111; I. Solvent Black 3, 7, 27, 29;
Specific examples of commercially available oil-soluble dyes include blue dye SBN blue 701 (Hodogaya Chemical Co., Ltd.), blue dye SPT blue 26 (Hodogaya Chemical Co., Ltd.), red dye savinyl pink 6BLS (Clariant Chemicals Co., Ltd.). Etc.

  The dispersion liquid of colored resin fine particles for water-based ink according to the present invention is obtained by dispersing colored resin fine particles composed of at least one monomer selected from Group A and a basic dye or oil-soluble dye in water. As a production method thereof, for example, at least one monomer selected from Group A or a mixture containing at least one monomer selected from Group A and a hydrophobic vinyl monomer The above basic dye or oil-soluble dye is dissolved in a monomer, and ammonium persulfate, potassium persulfate, hydrogen peroxide, azobisisobutyronitrile, etc. are used as a polymerization initiator, and a polymerization initiator is further used in combination with a reducing agent. Further, if necessary, it can be produced by emulsion polymerization using a polymerizable surfactant. Moreover, although the said dyeing | staining was performed simultaneously with superposition | polymerization, you may dye | stain by dissolving a basic dye or an oil-soluble dye after superposition | polymerization.

In the present invention, at the time of the emulsion polymerization, emulsion polymerization may be carried out by further mixing dicyclopenta (te) nyl (meth) acrylate monomer or the like with the group A monomer. This dicyclopenta (te) nyl (meth) acrylate monomer is further mixed and emulsion polymerized, and even if the water in the dispersion is volatilized, the stability is hardly impaired, and the color for water-based ink is further excellent in stability. A dispersion of resin fine particles can be obtained.
Examples of dicyclopenta (te) nyl (meth) acrylate monomers that can be used include dicyclopentanyl acrylate monomer, dicyclopentenyl acrylate, dicyclopentanyl methacrylate monomer, and dicyclopentenyl methacrylate.
In the present invention, in the emulsion polymerization, in addition to the group A monomer, the hydrophobic vinyl monomer, and the dicyclopenta (te) nyl (meth) acrylate monomer, an epoxy group, a hydroxymethylamide group, an isocyanate group A monomer having a reactive crosslinking group such as a polyfunctional monomer having two or more vinyl groups may be blended for crosslinking.

In the present invention, among the polymer components constituting the colored resin fine particles for water-based ink, the total content of the monomer of Group A and the hydrophobic vinyl monomer that can be preferably used is color development, weather resistance, and stability. In addition to the function as a coloring material such as, from the point of improving the drawn line dryness and further exhibiting the effect of the present invention, it is preferably 60% by mass or more, more preferably 70% by mass or more in the polymer composition. 100 mass% is desirable.
Particularly preferably, the content of at least one monomer selected from Group A is 40% by mass or more, and the content of the hydrophobic vinyl monomer is preferably 20% by mass or more. .
Among the polymer components constituting the colored resin fine particles for water-based ink, when the dicyclopenta (te) nyl (meth) acrylate monomer is used, it is contained from the viewpoint of stability and further improvement of ink performance. The amount is preferably 0 to 25% by mass, more preferably 1 to 25% by mass, and particularly preferably 5 to 15% by mass.

  In the present invention, the content of the basic dye or oil-soluble dye is preferably based on the total amount of monomers used including the group A from the viewpoint of functions as a coloring material such as color developability, weather resistance, and stability. 0.2 to 50 mass%, more preferably 0.5 to 10 mass%.

  The polymerizable surfactant that can be used as necessary is not particularly limited as long as it is a polymerizable surfactant that is usually used in the emulsion polymerization. For example, the polymerizable surfactant may be an anionic surfactant. Or a nonionic polymerizable surfactant, Adeka Soap NE-10, NE-20, NE-30, NE-40, NE-40, SE-10N, and Kao Corporation. Latemul S-180, S-180A, S-120A, Elemiol JS-20, RS-3000, CLS-20 from Sanyo Chemical Industries, Ltd., Aqualon KH from Daiichi Kogyo Seiyaku Co., Ltd. -05, the same KH-10, the same HS-10, the same AR-10, the same RN-10, and the like. The amount of these polymerizable surfactants used is 0 to 50% by mass, preferably 0.1 to 50% by mass, based on the total amount of the monomers.

In the present invention, the aforementioned basic dye or oil-soluble dye is dissolved in the above preferred embodiment, specifically, a monomer containing at least 40% by mass of at least one monomer of Group A, and emulsion polymerization is performed. Or by dissolving and dyeing a basic dye or oil-soluble dye after polymerization of a mixed monomer containing at least 40% by mass or more of at least one kind of monomer of Group A, so that the resin solid content is 20 to 50 mass A dispersion of colored resin fine particles for water-based ink in which% colored resin fine particles are dispersed in water is obtained.
This dispersion of colored resin fine particles has a coloring material having excellent functions such as color developability, weather resistance, and stability, and is a water-based ink composition for writing instruments suitable for writing instruments such as sign pens, marking pens, and ballpoint pens. It is useful as a color material.

Further, colored resin fine particles polymerized by further using the dicyclopenta (te) nyl (meth) acrylate monomer are dispersed in water, and the dispersion liquid has functions as a colorant such as the above-described color developability, weather resistance, and stability. As a result, a dispersion of colored resin fine particles for water-based inks, which has an improved property of improving the dryness of drawn lines, and whose stability is not easily impaired even if moisture is volatilized, is obtained.
In the present invention, the average particle diameter of the colored resin fine particles in the dispersion of the colored resin fine particles for aqueous ink obtained varies depending on the monomer type, content, polymerization conditions during polymerization, etc. The thickness is 8 μm or less, and the pen core of a writing instrument such as a sign pen, marking pen, or ballpoint pen is not clogged and has excellent storage stability. The “average particle diameter” defined in the present invention is a value of D50 measured with a particle size distribution measuring apparatus [FPAR1000 (manufactured by Otsuka Electronics)].

The aqueous ink composition for a writing instrument of the present invention contains at least a dispersion of colored resin fine particles having the above-described configuration and at least one antioxidant selected from Group B below.
Group B:
Polyphenols, cysteines, ascorbic acids, oligomers of polyvinylpyrrolidone, butylhydroxyanisole (BHA)

When the dispersion liquid of colored resin fine particles for water-based ink is used as a coloring material for water-based ink for writing instruments, if the pH is in the alkaline region, discoloration or aggregation may occur over time. However, in the present invention, by containing at least one kind of antioxidant selected from the above-mentioned group B, there is no occurrence of discoloration or aggregation over time, and good stability over time. Will be able to.
The polyphenols that can be used are those having a phenolic molecule having a plurality of hydroxy groups. Specifically, catechins (epicatechin, epigallocatechin, epicatechin gallate, epigallocatechin gallate, etc.), tannic acid Tannin, chlorogenic acid, caffeic acid, neochlorogenic acid, cyanidin, proanthocyanidin, thearvidin, rutin, flavonoids (such as quercitrin, anthocyanins, flavanones, flavanols, flavonols, isoflavones), flavones, chalcones (such as naringenin chalcone), xanthophyll, Carnosic acid, eriocitrin, nobiletin, tangerine, magnolol, honokiol, ellagic acid, lignan, curcumin, coumarin, catechol, procyanidin, theafra , Rosmarinic acid, xanthone, quercetin, resveratrol, gallic acid, propyl gallate, fluorotannin, piceatannol [5- (dihydroxyphenylethenyl) resorcin], resveratrol (3,5,4'-tri Hydroxy-trans-stilbene) and the like.

Examples of cysteines that can be used include (L-) cysteine, N-acetyl-L-cysteine, (L-) cysteine hydrochloride, (L-) cysteine ethyl ester hydrochloride, and (L-) cysteine methyl ester. Examples thereof include hydrochloride, glutathione (tripeptide of glutamic acid / cysteine / glycine), oxidized glutathione, and γ-L-glutamyl-L-cysteine (dipeptide of glutamic acid / cysteine).
Ascorbins that can be used include ascorbic acid and its derivatives (including stereoisomers). Ascorbic acid may be any of L-form, D-form, and DL-form, but L-form is preferred from the viewpoint of availability. Examples of derivatives of ascorbic acid include sodium ascorbate, potassium ascorbate, calcium ascorbate, ascorbic acid phosphate, magnesium salt of ascorbic acid phosphate, ascorbic acid sulfate, ascorbic acid sulfate disodium salt, ascorbine Ascorbic acid 2-glucoside, ascorbyl palmitate, tetraisopalmitate ascorbyl and the like; stearic acid ascorbyl ester, tetraisopalmitic acid ascorbyl ester, ascorbyl fatty acid esters such as palmitate ascorbyl ester, etc. Can be mentioned.

The oligomer of vinyl pyrrolidone (N-vinyl-2-pyrrolidone) that can be used is a linear polymer (average degree of polymerization n) of-[C ₆ H ₉ NO] n- and has various functions. However, in the present invention, the antioxidant yield is exhibited. The vinyl pyrrolidone oligomer preferably has an average polymerization degree n of 2 to 20 from the viewpoint of ink viscosity, antioxidant performance, etc., and two or more oligomers having different polymerization degrees are used in combination in the ink. You may do it.

  In the present invention, at least one selected from the group B antioxidants (each alone or a mixture of two or more) can be used, and among these, an effect can be obtained stably and continuously. Therefore, it is preferable to use chlorogenic acid, caffeic acid, tannic acid, L-ascorbic acid, piceatannol, and resveratrol.

The content of these antioxidants is preferably 0.01 to 30% by mass, more preferably 0.1 to 5% by mass, based on the total amount of the aqueous ink composition for writing instruments. It is desirable.
If the content of the oxygen-absorbing component is less than 0.01% by mass, the effects of the present invention cannot be exhibited. On the other hand, if the content exceeds 30% by mass, the stability of the ink may be impaired.

The aqueous ink composition for a writing instrument of the present invention further comprises a water-soluble organic solvent and water in addition to the dispersion of colored resin fine particles having the above-described configuration and at least one antioxidant selected from Group B above. It is desirable to do.
Examples of water-soluble organic solvents that can be used include ethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, 1,2-propanediol, 1,3-propanediol, and 1,2-butane. Diol, 2,3-butanediol, 1,3-butanediol, 1,4-butanediol, 1,2-pentanediol, 1,5-pentanediol, 2,5-hexanediol, 3-methyl 1,3 -Butanediol, 2-methylpentane-2,4-diol, alkylene glycols such as 3-methylpentane-1,3,5 triol, 1,2,3-hexanetriol, and polyalkylene glycols such as polyethylene glycol and polypropylene glycol , Glycerol, jig Glycerols such as serol and triglycerol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, dialkylene glycol mono-n-butyl ether and other lower alkyl ethers of N-methyl-2-pyrrolidone , 1,3-dimethyl-2-imidazolidinone and the like.

In addition, for example, alcohols such as methyl alcohol, ethyl alcohol, isopropyl alcohol, n-butyl alcohol, tert-butyl alcohol, isobutyl alcohol, hexyl alcohol, octyl alcohol, nonyl alcohol, decyl alcohol, benzyl alcohol, dimethylformamide, Water-soluble solvents such as amides such as diethylacetamide and ketones such as acetone can also be mixed.
The content of these water-soluble organic solvents varies depending on the type of writing instrument such as sign pens, marking pens, and ballpoint pens, and is 1 to 40% by mass relative to the total amount of the ink composition. Therefore, it is particularly effective for an ink composition of 10% by mass or less, more preferably 3 to 8% by mass.

  Further, the content of water (tap water, purified water, ion-exchanged water, distilled water, pure water, etc.) is preferably 30 to 90% by mass, more preferably 40 to 60% by mass with respect to the total amount of the ink composition. is there.

In the water-based ink composition for a writing instrument of the present invention, a preservative or antifungal agent, a pH adjuster, an antifoaming agent, and the like can be appropriately selected and used as necessary within a range not impairing the effects of the present invention. .
For example, as pH adjusters, ammonia, urea, monoethanolamine, diethanolamine, triethanolamine, aminomethylpropanol, sodium tripolynate, sodium carbonate and other alkali metal salts of carbonic acid and phosphoric acid, and alkali metal water such as sodium hydroxide There may be mentioned at least one kind such as an oxide.
As preservatives or antifungal agents, phenol, sodium omadin, sodium pentachlorophenol, 1,2-benzisothiazoline 3-one, 2,3,5,6-tetrachloro-4 (methylphonyl) pyridine, benzoic acid and sorbine Examples thereof include at least one of an acid, an alkali metal salt of dehydroacetic acid, a benzimidazole compound, and the like.
Lubricants such as phosphate esters, polyalkylene glycol derivatives such as polyoxyethylene lauryl ether, fatty acid alkali salts, nonionic surfactants, fluorosurfactants such as perfluoroalkyl phosphate esters, dimethylpolysiloxane polyethylene glycol Examples include at least one of polyether-modified silicone such as an adduct.

  The water-based ink composition for a writing instrument of the present invention comprises at least a dispersion of colored resin fine particles for water-based ink having the above-described configuration, at least one antioxidant selected from Group B, a water-soluble solvent, and other components. Are combined as appropriate according to the application of ink for writing instruments (for ballpoint pens, marking pens, etc.) and mixed by stirring with a stirrer such as a homomixer, homogenizer or disper, and if necessary, by filtration or centrifugation. An aqueous ink composition for writing instruments can be prepared by removing coarse particles in the ink composition.

The writing instrument of the present invention is equipped with a water-based ink composition for a writing instrument having the above composition, and includes, for example, a pen tip portion such as a ballpoint pen tip, a fiber tip, a felt tip, a plastic tip, a fiber core, and a porous core. Mounted on ballpoint pens, marking pens, etc.
As a ballpoint pen, the water-based ink composition for writing instruments having the above composition is accommodated in an ink container (refill) for ballpoint pens and is not compatible with the water-based ink composition for writing instruments having the above composition contained in the ink container. In addition, a substance having a specific gravity smaller than that of the water-based ink composition, for example, polybutene, silicone oil, mineral oil, or the like is accommodated as an ink follower.
The structure of the ballpoint pen and the marking pen is not particularly limited. For example, a collector structure (ink holding mechanism) in which the shaft tube itself is used as an ink container and the water-based ink composition for a writing instrument having the above configuration is filled in the shaft tube. It may be a direct liquid ballpoint pen or a marking pen provided.

  In the aqueous ink composition for a writing instrument of the present invention configured as described above, the colored resin fine particles composed of at least one monomer selected from Group A and a basic dye or an oil-soluble dye are water. The pH of the ink composition is set in an alkaline region or the like by containing a dispersion of colored resin fine particles for water-based ink dispersed in and at least one antioxidant selected from Group B. However, a water-based ink composition for a writing instrument suitable for a writing instrument such as a sign pen, a marking pen, and a ballpoint pen, which does not cause discoloration or aggregation with time and has excellent temporal stability, can be obtained.

  Next, the present invention will be described in more detail with reference to production examples, examples and comparative examples, but the present invention is not limited to the following examples.

[Production Examples 1 to 5: Production of dispersion of colored resin fine particles]
According to the following Production Examples 1 to 5, dispersions of colored resin fine particles were produced.

(Production Example 1)
A 2 liter flask was equipped with a stirrer, reflux condenser, thermometer, nitrogen gas inlet tube, 1000 ml separatory funnel for monomer introduction, set in a hot water tank, 500 g of distilled water, polymerizable surfactant [manufactured by ADEKA 50 g of “ADEKA rear soap SE-10N”] and 3 g of ammonium persulfate were charged, and the internal temperature was raised to 50 ° C. while introducing nitrogen gas.

On the other hand, as a monomer of Group A, 500 g of a mixed monomer composed of 300 g of phthalic acid-2-methacryloyloxyethyl phthalate (manufactured by Mitsubishi Rayon Co., Ltd., acrylic ester PA) and 200 g of n-butyl methacrylate as another monomer, A liquid was prepared by mixing 40 g of a water-soluble basic dye [manufactured by Hodogaya Chemical Co., Ltd., “AIZEN CATHILON RED BLH 200%”].
This preparation solution was added from the separatory funnel to the flask maintained at a temperature of about 50 ° C. over 3 hours with stirring to carry out emulsion polymerization. The polymerization was completed after aging for 5 hours to obtain a dispersion (particle 1) of colored resin fine particles for aqueous ink.

(Production Example 2)
In the said manufacture example 1, except having used 300 g of 2-acryloyloxyethylphthalic acid [Kyoeisha Chemical Co., Ltd. product: HOA-MPL (N)] as a monomer of A group, A colored fine particle aqueous dispersion (particle 2) for aqueous ink was obtained.

(Production Example 3)
In the above Production Example 1, except that 300 g of hexahydrophthalic acid-2-methacryloyloxyethyl (manufactured by Mitsubishi Rayon Co., Ltd., acrylic ester HH) was used as the monomer of Group A, the same as in Production Example 1 above, A colored fine particle aqueous dispersion (particle 3) for aqueous ink was obtained.

(Production Example 4)
In the said manufacture example 1, it is the same as that of the said manufacture example 1 except having used 2-acryloyloxyethyl hexahydrophthalic acid [Kyoeisha Chemical Co., Ltd. product: HOA-HH (N)] 300g as a monomer of A group. Thus, an aqueous colored fine particle dispersion (particle 4) for water-based ink was obtained.

(Production Example 5)
In Production Example 1, Production Example 1 except that 300 g of 2-acryloyloxyethyl-2-hydroxyethylphthalic acid [manufactured by Kyoeisha Chemical Co., Ltd .: HOA-MPE (N)] was used as the monomer of Group A. In the same manner as above, a colored fine particle aqueous dispersion (particle 5) for aqueous ink was obtained.
The dispersion of colored resin fine particles for each water-based ink obtained in Production Examples 1 to 5 has an average particle size in the range of 0.05 to 0.30 μm and the resin solid content in the range of 10 to 50% by mass. there were.

[Examples 1 to 11 and Comparative Examples 1 to 5: Preparation of water-based ink composition for writing instruments]
Using the colored resin fine particle dispersions (particles 1 to 5) produced in the above Production Examples 1 to 5, the aqueous composition for each writing instrument was prepared in a conventional manner according to the composition shown in Tables 1 and 2 below (total amount: 100% by mass). An ink composition was prepared.

About each obtained water-based ink composition for writing instruments (100 mass% of whole quantity), the pH of an ink composition and stability with time were evaluated by the following evaluation method.
Table 1 and Table 2 below show the evaluation results of Examples 1 to 11 and Comparative Examples 1 to 5, respectively.

(Measurement method of pH of ink composition)
The pH (25 ° C.) of each ink composition prepared in Examples 1 to 11 and Comparative Examples 1 to 5 obtained above was measured. The pH was measured by HORIBA pH / ION METER F-23 (manufactured by HORIBA).

(Evaluation method of stability over time)
Each ink composition prepared in Examples 1 to 11 and Comparative Examples 1 to 5 obtained above was filled in a glass vial, the lid was closed, and the product was stored in an environment of 50 ° C. The period during which no ink was aggregated or settled was defined as the “period during which the stability was maintained”, and the following evaluation criteria were used.
Evaluation criteria:
A: More than 3 months
○: 1 month or more and less than 3 months
Δ: 2 weeks or more and less than 1 month
×: Less than 2 weeks

  Considering Table 1 and Table 2 above, it can be seen that Examples 1 to 11 that are within the scope of the present invention are superior in stability over time as compared with Comparative Examples 1 to 5 that are outside the scope of the present invention. In particular, in Examples 1 to 5, water for writing instruments using chlorogenic acid, caffeic acid, tannic acid, L-ascorbic acid, piceatannol, resveratrol as selected from the group B antioxidants. It can be seen that the ink composition exhibits particularly excellent temporal stability.

In addition, using the aqueous ink composition for each writing instrument after the evaluation of temporal stability in Examples 1 to 11 obtained above, ball pens and marking pens having the following configurations were prepared, and written on writing paper. Written performance was evaluated.
(Writing instrument: making a ballpoint pen)
Using a shaft of a ballpoint pen [Mitsubishi Pencil Co., Ltd., trade name: Signo UM-100], inner diameter 4.0 mm, length 113 mm polypropylene ink containing tube and stainless steel tip (carbide ball, ball diameter 0.7 mm ) And a refill made of a joint connecting the housing tube and the tip was filled with each water-based ink composition, and an ink follower mainly composed of mineral oil was loaded at the rear end of the ink to produce a water-based ballpoint pen.
(Writing instrument: Production of marking pen)
A marking pen (made by Mitsubishi Pencil Co., Ltd., trade name: Propass Window PUS-102T, pen tip, thick: PE resin core, fine: PET fiber core) is loaded with each of the above water-based ink compositions. Produced.
It was confirmed that both the ballpoint pen and the marking pen were free of blurring and did not blur and became clear writing lines.

  A water-based ink composition for writing instruments suitable for writing instruments such as sign pens, marking pens, and ballpoint pens can be obtained.

Claims (3)

A dispersion of colored resin fine particles for aqueous ink in which colored resin fine particles composed of at least one monomer selected from the following group A and a basic dye or an oil-soluble dye are dispersed in water; A water-based ink composition for a writing instrument, comprising at least one antioxidant selected from Group B.
Group A:
Phthalic acid-2-methacryloyloxyester, phthalic acid-2-acryloyloxyester, hexahydrophthalic acid-2-methacryloyloxyethyl, hexahydrophthalic acid-2-acryloyloxyethyl, 2-acryloyloxyethyl-2-hydroxy Ethyl-phthalic acid, 2-methacryloyloxyethyl-2-hydroxyethyl-phthalic acid Group B:
Polyphenols, cysteines, ascorbic acids, polyvinylpyrrolidone oligomers, butylhydroxyanisole   The writing instrument according to claim 1, wherein the at least one antioxidant selected from the group B is chlorogenic acid, caffeic acid, tannic acid, L-ascorbic acid, piceatannol, resveratrol. Water-based ink composition.   A writing instrument comprising the aqueous ink composition for a writing instrument according to claim 1 or 2 mounted thereon.