JP2015089891A - Ink composition for oil-based ballpoint pen and oil-based ballpoint pen using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oil-based ink composition for a ball point pen having excellent flow-down properties of an ink, and an oil-based ballpoint pen using the same.SOLUTION: An oil-based ink composition for a ball point pen at least includes a coloring agent, an organic solvent, and a dextrin carboxylate ester. An oil-based ball point pen uses the composition.

Description

  The present invention relates to an ink composition for oil-based ballpoint pens and an oil-based ballpoint pen using the same.

  Conventionally, in an oil-based ballpoint pen ink composition, a solvent having a vapor pressure at 25 ° C. of 0.001 mmHg or more is used to suppress ink sag from the gap between the ball and the tip of the tip. There has been proposed a technique for an oil-based ballpoint pen ink composition using silica or terpene phenol resin or having a high ink viscosity.

As such an oil-based ink composition for ballpoint pens, as a technique using an alcohol, a polyhydric alcohol, or a glycol ether solvent having a vapor pressure at 25 ° C. of 0.001 mmHg or more, Japanese Patent Application Laid-Open No. 2004-107591 “Oil Properties” As a technique using a ballpoint oil-based ink composition "or an ink sag inhibitor, the primary average particle diameter is 7 to 40.
Japanese Patent Application Laid-Open No. 10-195365 “Oil-based ink for ball-point pen” using silica of nm and technology using terpene phenol resin having an OH value of 150 or more include “Oil-based ink for ball-point pen”. Is disclosed.

"Japanese Patent Laid-Open No. 2004-107591" "Japanese Patent Laid-Open No. 10-195365" "JP 2007-126528 A"

  However, in Patent Document 1, it is possible to suppress ink drooping to some extent, but when the ink viscosity is lowered, the solvent used in Patent Document 1 alone is not sufficient.

  In Patent Document 2, since the particle size is small, the dispersion stability in oil-based ink is poor, and in Patent Document 3, since the OH value is large, the solubility in oil-based ink is poor and sufficient effects are exhibited. could not.

  Recently, in order to obtain a smooth writing feeling, the ink viscosity of oil-based inks has been lowered, and the ink discharge amount has increased accordingly, and there has been a problem that ink dripping is likely to occur from the gap between the ball and the tip of the tip.

  The objective of this invention is providing the ink composition for oil-based ball-point pens which made ink dripping performance favorable, and an oil-based ball-point pen using the same.

In order to solve the above problems, the present invention
“1. An oil-based ballpoint pen ink composition comprising at least a colorant, an organic solvent, and a dextrin carboxylic acid ester.
2. 2. The oil-based ballpoint pen ink composition according to claim 1, wherein the dextrin carboxylic acid ester is a dextrin ester of a branched carboxylic acid and / or a dextrin ester of an aromatic carboxylic acid.
3. Item 3. The ink composition for oil-based ballpoint pens according to Item 1 or 2, wherein the content of the dextrin carboxylic acid ester is 0.5 to 10.0% by mass.
4. The ink composition for oil-based ballpoint pens according to any one of Items 1 to 3, wherein the ink viscosity at 20 ° C. and a shear rate of 5 sec ⁻¹ is 3000 mPa · s or more.
5. The ink composition for oil-based ballpoint pens according to any one of items 1 to 4, wherein the ink composition for oil-based ballpoint pens contains a polyvinyl butyral resin and / or a ketone resin.
6). The ink composition for oil-based ballpoint pens according to any one of claims 1 to 5, wherein the organic solvent contains at least an aromatic glycol solvent.
7). The oil-based ballpoint pen according to any one of claims 1 to 6, wherein a ballpoint pen tip holding a ball rotatably is attached to a tip portion of the ink containing cylinder directly or via a chip holder. 7. An oil-based ballpoint pen refill containing an ink composition for ink and having a movement amount in the axial direction of the ball of 5 to 20 [mu] m is disposed. Oil-based ballpoint pen.
8). The oil-based ballpoint pen refill is a retractable oil-based ballpoint pen that is slidably disposed in the shaft cylinder, and the tip end portion of the ballpoint pen tip can protrude and retract from the tip end portion of the shaft cylinder. The oil-based ballpoint pen described in 1. "

  The present invention quickly forms a film at the tip of the tip, and covers the gap between the ball and the tip of the tip with a strong coating, thereby suppressing ink leakage and an ink composition for an oil-based ballpoint pen having good ink drooping performance. The oil-based ballpoint pen used could be provided.

  A feature of the present invention is that the oil ballpoint ink composition contains a dextrin carboxylic acid ester.

The dextrin carboxylic acid ester used in the present invention is a polymer ester in which dextrin and carboxylic acid are esterified.
Therefore, the inventor of the present application contains a dextrin carboxylic acid ester in the oil-based ballpoint pen ink composition so that when the tip end is left in the air, the dextrin carboxylic acid ester quickly forms a film, It was found that by covering the gap between the tip of the tip with a strong film, ink leakage was suppressed and ink drooping performance was improved. Further, the carboxylic acid ester portion side of the dextrin carboxylic acid ester is preferably used because it is easily compatible with an organic solvent and is stable.
Furthermore, the dextrin carboxylic acid ester film has an effect of suppressing evaporation of the organic solvent in the ink, and can increase the viscosity of the ink, and is more preferably used.

  For dextrin carboxylic acid ester, specifically, dextrin ester of branched carboxylic acid such as isostearic acid, dextrin ester of aromatic carboxylic acid such as benzoic acid, lauric acid, myristic acid, palmitic acid, stearic acid, And dextrin esters of linear carboxylic acids such as oleic acid. Among them, a branched carboxylic acid dextrin ester and an aromatic carboxylic acid dextrin ester are preferable in consideration of being easily compatible with an organic solvent and stable, and a branched carboxylic acid is particularly preferable in consideration of ink sag. The dextrin ester of isostearic acid is most preferable in consideration of the dextrin ester.

  The dextrin carboxylic acid ester preferably has a melting point of 100 ° C. or lower. This is because when the melting point exceeds 100 ° C. and the melting point is high, the bonds between the molecules of the dextrin carboxylic acid ester become strong and the cohesive strength of the dextrin carboxylic acid ester film increases, so that a stable film that is hard to break is formed. It tends to be difficult, and tends to affect the suppression of ink sag. Furthermore, in consideration of suppression of ink dripping, the melting point is preferably 80 ° C. or less, and most preferably the melting point is 50 ° C. to 70 ° C.

  The content of the dextrin carboxylic acid ester is preferably 0.5 to 10.0% by mass with respect to the total amount of the ink composition. This is because if the amount is less than 0.5% by mass, the amount of film formation may be insufficient, and the ink drooping performance tends to be inferior. Further, if it exceeds 6.0% by mass, the formed film tends to be blurred at the time of writing, so 0.5 to 6.0% by mass is preferable. Is most preferred.

The ink viscosity of the oil-based ballpoint pen ink composition of the present invention is not particularly limited. However, when the ink viscosity at 20 ° C. and a shear rate of 5 sec ⁻¹ is 3000 mPa · s or more, ink leakage occurs from the gap between the ball and the tip of the tip. It is preferable because it is easy to suppress ink sag by a dextrin carboxylic acid ester film before the occurrence of ink, and when the ink viscosity at 20 ° C. and a shear rate of 5 sec ⁻¹ exceeds 50000 mPa · s, the writing quality tends to be inferior. The ink viscosity at ° C. and a shear rate of 5 sec ⁻¹ is preferably 3000 to 50000 mPa · s. In consideration of further improving ink drooping performance and writing quality, the ink viscosity is more preferably 4000 to 30000 mPa · s, and further more preferably 5000 to 25000 mPa · s.

  In order to further improve the ink drooping performance, it is preferable to use a resin in combination. As the resin, polyvinyl butyral resin, ketone resin, polyacetal resin, polyvinyl alcohol resin, cellulose resin, polyvinyl pyrrolidone resin, terpene Examples thereof include resins, alkyd resins, phenoxy resins, and polyvinyl acetate resins. Among them, it is preferable to contain a polyvinyl butyral resin and / or a ketone resin. This is because it is easier to improve the ink drooping performance by forming a stronger film.

  In view of improving the ink drooping performance, it is most preferable to use a polyvinyl butyral resin. This is because the dextrin carboxylic acid ester and the polyvinyl butyral resin are used in combination to form a stronger film, thereby further improving the ink drooping performance and suppressing the evaporation of the organic solvent in the ink. Because. Here, the polyvinyl butyral resin is obtained by reacting polyvinyl alcohol (PVA) with butyraldehyde (BA) and has a structure having a butyral group, an acetyl group, and a hydroxyl group.

  The content of the polyvinyl butyral resin is preferably 50% or more with respect to the total resin content, and is preferably used as the main resin. This is because when the polyvinyl butyral resin content is less than 50% of the total resin content, the formation of a resin film on the tip of the chip is inhibited by other resins, making it difficult to suppress ink drooping, and the elasticity is further increased. This is because the formation of a certain ink layer is hindered, and the effect of improving the writing quality is hardly obtained. Considering the tendency to improve ink sag performance and writing quality, the content of polyvinyl butyral resin is preferably 70% or more with respect to the total resin content, and further considering that tendency, 90% or more. preferable.

  Of the polyvinyl butyral resins, it is preferable to use a polyvinyl butyral resin having a hydroxyl amount of 25 mol% or more. This is because the polyvinyl butyral resin forms a resin film, but the polyvinyl butyral resin having a hydroxyl group content of less than 25 mol has a slightly poor solubility in an organic solvent, and it is difficult to form a uniform resin film. This is because it is difficult to obtain. Further, considering the ink sag performance, a polyvinyl butyral resin having a hydroxyl amount of 30 mol% or more is preferable because it is compatible with the dextrin carboxylic acid ester and easily forms a more uniformly strong resin film. When a polyvinyl butyral resin having a hydroxyl group content exceeding 40 mol% is used, the amount of moisture absorption tends to increase, and the temporal stability with the oil-based ink component tends to be affected. Therefore, a polyvinyl butyral resin having a hydroxyl group content of 40 mol% or less is preferred. Therefore, a polyvinyl butyral resin having a hydroxyl amount of 30 to 40 mol% is preferable, and a hydroxyl group amount of 30 to 36 mol% is more preferable.

  Further, regarding the average degree of polymerization of the polyvinyl butyral resin, if the average degree of polymerization is 200 or more, the ink drooping performance is likely to be improved, and if the average degree of polymerization exceeds 2500, the ink viscosity becomes too high. The average degree of polymerization is preferably 200 to 2500 because it tends to affect writing quality. Furthermore, if the writing quality is taken into consideration, the average degree of polymerization is preferably 2000 or less. For this reason, the average degree of polymerization is preferably 200 to 2000, and when the average degree of polymerization is 1200 or more, the ink dripping performance tends to be improved. Therefore, the average degree of polymerization is most preferably 1200 to 2000. Here, the average degree of polymerization means the number of basic units constituting one molecule of the polyvinyl butyral resin, and a value measured based on the method defined in JIS K6728 (2001 version) can be adopted. .

  If the content of the polyvinyl butyral resin is less than 3.0% by mass relative to the total amount of the ink composition, the amount of resin film formation may be insufficient, and the ink drooping performance tends to be inferior, and exceeds 40.0% by mass. Since the solubility in the ink tends to be inferior, 3.0 to 40.0% by mass is preferable with respect to the total amount of the ink composition. Furthermore, if considering the ink drooping performance, 10.0% by mass or more is preferable, and if it exceeds 30.0% by mass, the ink viscosity tends to be too high and affects the writing quality. 0% by mass is preferable, and 12.0 to 20.0% by mass is most preferable in consideration of the above.

  As for the polyvinyl butyral resin, specifically, trade names manufactured by Sekisui Chemical Co., Ltd .; ESREC BH-3 (hydroxyl group amount: 34 mol%, average degree of polymerization: 1700), BH-6 (hydroxyl group amount: 30 mol%). , Average polymerization degree: 1300), BX-1 (hydroxyl group amount: 33 ± 3 mol%, average polymerization degree: 1700), BX-5 (hydroxyl group quantity: 33 ± 3 mol%, average polymerization degree: 2400), BM -1 (hydroxyl group amount: 34 mol%, average degree of polymerization: 650), BM-2 (hydroxyl group amount: 31 mol%, average degree of polymerization: 800), BM-5 (hydroxyl group amount: 34 mol%, average degree of polymerization: 850) ), BL-1 (hydroxyl group amount: 36 mol%, average polymerization degree: 300), BL-1H (hydroxyl group amount: 30 mol%), BL-2 (hydroxyl group amount: 36 mol%, average polymerization degree: 450), same L-2H (hydroxyl content: 29 mol%), BL-10 (hydroxyl content: 28 mol%), etc., trade name of Kuraray Co., Ltd .; Mobital B20H (hydroxyl content: 26-31 mol%, average degree of polymerization: 250) -500), 30T (hydroxyl group amount: 33-38 mol%, average polymerization degree: 400-650), 30H (hydroxyl group amount: 26-31 mol%, average polymerization degree: 400-650), 30HH (hydroxyl group amount: 30-34 mol%, average polymerization degree: 400-650), 45H (hydroxyl group amount: 26-31 mol%, average polymerization degree: 600-850), 60T (hydroxyl group amount: 34-38 mol%, average polymerization degree: 750) -1000), 60H (hydroxyl group amount: 26-31 mol%, average degree of polymerization: 750-1000), 75H (hydroxyl group amount: 26-31 mol%, average degree of polymerization: 1). 500-1750). You may use these individually or in mixture of 2 or more types.

   Resins other than polyvinyl butyral resin and ketone resin may be appropriately used as an ink viscosity modifier and a spinnability imparting agent. In particular, it is preferable to contain a polyvinyl pyrrolidone resin, since the incorporation of the polyvinyl pyrrolidone resin increases the binding property of the ink and suppresses the generation of excess ink at the tip of the chip. When the content of the polyvinyl pyrrolidone resin is less than 0.01% by mass relative to the total amount of the ink composition, it tends to be difficult to suppress the generation of excess ink. Since there exists a tendency for solubility to be inferior, 0.01-3.0 mass% is preferable with respect to the ink composition whole quantity. Considering the above reasons, 0.1 to 2.0% by mass is preferable. Specific examples include trade names of IP Japan Co., Ltd .; PVP K-15, PVP K-30, PVP K-90, PVP K-120, and the like. You may use these individually or in mixture of 2 or more types.

  As for the colorant used in the present invention, there are dyes and pigments. As for the dyes, there are oil-soluble dyes, acid dyes, basic dyes, metal-containing dyes, direct dyes, and various salt-forming dyes. It can be adopted. Examples of the pigment include inorganic, organic and processed pigments. These dyes and pigments can be used in combination of two or more. Among the colorants, in order to obtain pigment dispersion stability when using a pigment, it is preferable to use only a dye because there are problems such as selection of the pigment dispersant and cost problems.

  Examples of dye types include salt-forming dyes of basic dyes and acid dyes, salt-forming dyes of basic dyes and organic acids, and salt-forming dyes of acid dyes and organic amines. It is preferable to use at least a salt-forming dye composed of a basic dye and an acid dye because it tends to affect stability and writing quality. In addition, regarding salt-forming dyes of basic dyes and acidic dyes, basic dyes include basic dyes such as xanthene skeleton, triallylmethane skeleton, azomethine skeleton, azo skeleton, anthraquinone skeleton, and oxazine skeleton. Include acid dyes such as triallylmethane skeleton, azo skeleton, anthraquinone skeleton, and oxazine skeleton, and can be obtained by salting these basic dyes or acid dyes.

  Specifically, Bali First Black 1802, Bali First Black 1805, Bali First Black 1807, Bali First Violet 1701, Bali First Violet 1704, Bali First Violet 1705, Bali First Blue 1601, Bali First Blue 1605, Bali First Blue 1613, Bali First Blue 1621, Bali First Blue 1631, Bali First Red 1320, Bali First Red 1360, Bali First Red 1380, Bali First Yellow 1101, Bali First Yellow 1151, (above, manufactured by Orient Chemical Industry Co., Ltd.), Eisenspiron Black GMH-Special, Eisenspiron Violet C-RH, Eisenspiron Blue NH, Eisenspiron Blue 2BNH, Eisenspiron Blue C-RH, Eisenspiron Red C-GH, Eisenspiron Red C-PH, Eisenspiron Red C-BH, Eisenspiron Yellow C-GNH, Eisenspiron Yellow C-2GH, S.M. P. T. T. et al. Blue 111, S.I. P. T. T. et al. Blue GLSH-special P. T. T. et al. Red 533, S.D. P. T. T. et al. Orange 6, S. B. N. Violet 510, S.I. B. N. Yellow 510, S.I. B. N. Yellow 530, S.I. R. C-BH (above, manufactured by Hodogaya Chemical Co., Ltd.) and the like.

  The content of the colorant is preferably 5.0 to 30.0% by mass with respect to the total amount of the ink composition. If the amount is less than 5.0% by mass, a dark handwriting tends to be difficult to obtain. If the amount exceeds 30.0% by mass, the solubility in ink tends to be affected. Considering it, 7.0 to 25.0 mass% is preferable, and further considering it is 10.0 to 20.0 mass%.

  Examples of the organic solvent used in the present invention include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol monophenyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol dimethyl ether, 3 -Glycol ether solvents such as methoxybutanol and 3-methoxy-3-methylbutanol, glycol solvents such as diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, butylene glycol and ethylene glycol, benzyl alcohol, methanol, ethanol , 1-propanol, 2- For oil-based ballpoint pens such as lopanol, isopropanol, isobutanol, t-butanol, propargyl alcohol, allyl alcohol, 3-methyl-1-butyn-3-ol, alcohol solvents such as ethylene glycol monomethyl ether acetate and other higher alcohols The organic solvent generally used as ink can be illustrated.

  Among these organic solvents, it is preferable to use a glycol ether solvent because dextrincarboxylic acid ester can easily suppress the evaporation amount of the organic solvent in the ink when a film is formed at the tip of the chip. Therefore, in the present invention, it is preferable to use at least a glycol ether solvent. An alcohol solvent is preferable because it easily volatilizes, is easy to dry at the tip of the chip, easily forms a resin film, and easily improves the ink drooping performance. In particular, in view of improving lubricity, it is preferable to have an aromatic ring. Therefore, it is preferable to use an aromatic glycol ether solvent and an aromatic alcohol solvent in combination. These organic solvents can be used alone or in combination of two or more.

  Further, the content of the organic solvent is preferably 10.0 to 70.0% by mass with respect to the total amount of the ink composition in consideration of improving solubility, handwriting drying property, bleeding, and the like. Further, the content of the glycol ether solvent is preferably 10.0 to 50.0% by mass with respect to the total organic solvent, more preferably, considering the dissolution stability with the dextrin carboxylic acid ester and the polyvinyl butyral resin. It is 10.0-30.0 mass%. Further, the content of the alcohol solvent is preferably 30.0 to 90.0% by mass, more preferably 50.0 to 90.0%, based on the total organic solvent, considering the drying property at the tip of the chip. % By mass.

  By the way, by using dextrin carboxylic acid ester as in the present invention, there is an effect of significantly improving the ink drooping performance, and in particular, when dextrin carboxylic acid ester and polyvinyl butyral resin are used in combination, it is more effective. Thus, it is necessary to use a structure that suppresses ink sag by constantly pressing the ball against the inner wall surface of the tip of the tip with a coil spring or the like in the tip body and closing the minute gap between the ball and the tip of the tip. In addition, since the ink dripping suppression effect is obtained, it is not necessary to provide a coil spring or the like in the chip body, which leads to a decrease in the number of parts, and can be suitably used for an intrusion type and / or a low priced product. .

  In the present invention, it is preferable to use a phosphate ester surfactant. This is because, in the phosphate ester-based surfactant, the phosphate group is easily adsorbed on the metal surface, the lubricity between the ball and the chip body is maintained, and the writing quality is easily improved. In particular, in the present invention, as described above, the ink layer and the phosphoric acid group formed by the polyvinyl butyral are more preferable because the lubricity is easily improved.

  Phosphate ester surfactants include polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphate monoester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphate diester, polyoxyethylene alkyl ether Or phosphoric acid triesters, alkyl phosphoric acid esters, alkyl ether phosphoric acid esters or derivatives thereof of polyoxyethylene alkylaryl ethers, and the alkyl group of the phosphoric acid ester type surfactant includes styrenated phenol type, nonylphenol Type, lauryl alcohol type, tridecyl alcohol type, octylphenol type and the like. These phosphate ester surfactants may be used alone or in combination of two or more. Among these, it is preferable that carbon number contained in an alkyl group is 5-15, and it is more preferable that it is 10-15. When the number of carbon atoms in the alkyl group is excessively small, lubricity tends to be insufficient, and when the number of carbon atoms is excessively large, the ink aging stability tends to be affected. Furthermore, phosphate ester surfactants tend to soften the film formed and may improve the writing performance. Therefore, unlike the cap-type writing tools, the pen tip is always exposed to the outside in the in-and-out writing tools such as the knock-type writing tools and the rotary pay-out writing tools, so it is easy to affect the writing performance. It is more preferable to use a surfactant.

  Further, the content of the phosphate ester-based surfactant is more preferably 0.1 to 5.0% by mass with respect to the total amount of the ink composition. This is because if it is less than 0.1% by mass, the desired lubricity tends to be difficult to obtain, and if it exceeds 5.0% by mass, the ink aging tends to become unstable, and this tendency Is considered to be 0.3 to 3.0% by mass relative to the total amount of the ink composition, and 0.5 to 3.0% by mass is most preferable considering more.

  Specific examples of the phosphate ester surfactant include Prisurf A217E (alkyl group: 14 carbon atoms, acid value: 45 to 58), A219B from the Prisurf series (Daiichi Kogyo Seiyaku Co., Ltd.). (Alkyl group: carbon number 12, acid value: 44 to 58), A215C (alkyl group: carbon number 12, acid value: 80 to 95), A208B (alkyl group: carbon number 12, acid value: 135 to 155) ), A208N (alkyl group: mixture of 12 and 13 carbon atoms, acid value: 160 to 185), phosphanol series (manufactured by Toho Chemical Co., Ltd.), phosphanol RB410 (alkyl group: carbon) No. 18, acid value: 80 to 90), RS-610 (alkyl group: carbon number 13, acid value: 75 to 90), RS-710 (alkyl group: carbon number 13, acid value: 55 to 75) Etc. It is. These surfactants may be used alone or in combination of two or more.

Furthermore, it is preferable to use an organic amine in the ink composition for an oil-based ballpoint pen of the present invention for the purpose of neutralizing a phosphate ester surfactant or the like. Examples of the organic amine include oxyethylene alkylamine, polyoxyethylenealkylamine, and the like, and alkylamines such as laurylamine, stearylamine, distearylamine, dimethyllaurylamine, dimethylstearylamine, and dimethyloctylamine. Among them, when an organic amine having ethylene oxide (CH ₂ CH ₂ O) is used, it is easy to obtain a lubricating effect. Therefore, oxyethylene alkyl amine and polyoxyethylene alkyl amine having ethylene oxide (CH ₂ CH ₂ O) Is preferably used.

  Regarding the reactivity between the organic amine and the other components in the ink, the primary amine is the strongest, and then the reactivity with the secondary amine and the tertiary amine is small. It is preferable to use a tertiary amine and / or a tertiary amine. You may use these individually or in mixture of 2 or more types.

  In addition, in the ink composition according to the present invention, as other additives, in order to improve lubricity and ink aging stability, (i) surfactants such as fluorine surfactants, silicone surfactants, (Ii) Viscosity adjustment of fatty acid alkanolamide, anionic surfactant, cationic surfactant, amphoteric surfactant, and an anionic surfactant and / or a salt-form of a cationic surfactant Agents such as fatty acid amides, pseudoplasticizers such as hydrogenated castor oil, (iii) colorant stabilizers, (iv) plasticizers, (v) chelating agents, or (vi) water as a co-solvent. You may use suitably. These may be used alone or in combination of two or more.

  Moreover, it is preferable that the moving amount | distance of the axial direction of the ball | bowl of the ball-point pen tip used for this invention shall be 5-20 micrometers. If it is less than 5 μm, the ink consumption will be reduced, and the handwriting will be easily blurred. If it exceeds 20 μm, the ink drooping performance will be easily affected. It is preferable to set it as 7-16 micrometers.

Example 1
The oil-based ballpoint pen ink composition of Example 1 is a dye as a colorant, benzyl alcohol as an organic solvent, ethylene glycol monophenyl ether, dextrin carboxylic acid ester, polyvinyl butyral resin, a phosphate ester surfactant as a lubricant, organic An oxyethylene alkylamine is used as the amine, and polyvinylpyrrolidone is used as the spinnability imparting agent. A predetermined amount of this is weighed and heated to 60 ° C., and then completely dissolved using a disper stirrer. Got. Specific blending amounts are as follows. Ink viscosity of Example 1 was measured using a viscometer RVDVII + Pro CP-52 spindle manufactured by Brookfield Co., Ltd. at a shear rate of 5 sec ⁻¹ (2.5 rpm) under an environment of 20 ° C. As a result, the ink viscosity was 6000 mPa · s.
Moreover, since the ink composition for oil-based ballpoint pens of the present invention is a Newtonian ink, the ink viscosity showed substantially the same numerical value even if the shear rate was different.

Example 1 (Ink formulation)
Colorant (dye, salt-forming dye of basic dye and acid dye) 18.0% by mass
Organic solvent (benzyl alcohol) 38.7% by mass
Organic solvent (ethylene glycol monophenyl ether) 25.8% by mass
Dextrin carboxylic acid ester (branched carboxylic acid dextrin ester)
2.0% by mass
Polyvinyl butyral resin (ESREC BL-1, hydroxyl group content: 36 mol%, average degree of polymerization: 300) 12.0 mass%
Lubricant (phosphate-based surfactant) 2.0% by mass
Organic amine (oxyethylene alkylamine) 1.0% by mass
Spinning agent (polyvinylpyrrolidone resin) 0.5% by mass

Examples 2-13
As shown in Tables 1 and 2, oil-based ballpoint pen ink compositions of Ink Distribution Examples 2 to 13 were obtained in the same procedure as Example 1 except that each component was changed. The measurement and evaluation results are shown in the table.

Comparative Examples 1-6
As shown in Table 3, oil-based ballpoint pen ink compositions of Comparative Examples 1 to 6 were obtained in the same procedure as in Example 1 except that each component was changed. The measurement and evaluation results are shown in the table.

Test and Evaluation The oil-based ballpoint pen ink composition (0.3 g) produced in Examples 1 to 13 and Comparative Examples 1 to 6 can be freely rotated in an ink containing cylinder (polypropylene) with a ball diameter of φ0.7 mm. An oil-based ballpoint pen refill with a ballpoint pen tip (the amount of movement of the ball in the axial direction of 14 μm) held therein was filled to prepare an oil-based ballpoint pen. The following tests and evaluations were performed using a writing paper JIS P3201 as a writing test paper.

Ink sag test: The sample was left for 7 days in an environment of 30 ° C. and 85% RH with the pen tip downward, and ink leakage from the tip of the tip was confirmed.
There are no ink droplets at the tip of the tip.
Ink droplets at the tip of the tip are within 1/4 of the taper.
Ink droplets at the tip of the tip are 1/4 or more and 1/2 of the taper part ... △
Ink drop on tip of tip is more than 1/2 of taper part ・ ・ ・ ×

Written taste: A hand-written sensory test was performed and evaluated.
Very smooth ・ ・ ・ ◎
What is smooth ・ ・ ・ ○
Smoothness of a level that is not a problem for practical use ・ ・ ・ △
Heavy thing

  In Examples 1 to 13, good performance was obtained in both the ink sag test and writing taste.

  In Comparative Examples 1 and 2, since dextrin carboxylic acid ester was not used, the ink dripping performance was poor.

  In Comparative Examples 3 to 6, although the viscosity of the ink was increased by adding a ketone resin or a fatty acid amide wax, since the dextrin carboxylic acid ester was not used, the ink dripping performance was poor.

Organic solvent evaporation test Refill for oil-based ballpoint pens filled with the ink composition for oil-based ballpoint pens prepared in Example 1 and Comparative Examples 1 and 2 was left for 10 days in a completely dry environment at 70 ° C. with the pen tip sideways. The amount of evaporation of the organic solvent was measured.
In Example 1, the evaporation amount was 6.1%. On the other hand, in Comparative Example 1, the evaporation amount was 7.0%, and in Comparative Example 2, the evaporation amount was 9.0%. From this, the amount of evaporation increases without using dextrin carboxylic acid ester, and it is easy to generate ink thickening, so the effect of dextrin carboxylic acid ester was confirmed.

  In addition, when using an oil-in-oil type ballpoint pen such as a knock-type oil-type ballpoint pen or a rotary pay-out type oil-type ballpoint pen, the ink drooping performance is one of the most important performances. It is effective to use an oil-based ballpoint pen ink that can be formed and covered with a strong film between the ball and the tip of the chip with a strong film to improve ink drooping performance.

  Further, in this embodiment, for the sake of convenience, an oil ballpoint pen containing an oil ballpoint pen refill that directly contains an ink composition for an oil ballpoint pen is illustrated in the shaft tube, but the oil ballpoint pen of the present invention includes a shaft tube. A direct-packing type oil-based ballpoint pen may be used in which an ink-containing tube is used and the ink composition for an oil-based ballpoint pen is directly stored in the shaft tube. Further, in this embodiment, for the sake of convenience, a ballpoint pen tip formed by cutting a wire rod is illustrated, but a ballpoint pen tip formed by pressing a pipe member may be used.

  The present invention is not limited to the ballpoint pens of the examples, and can be suitably used for marking pens, fountain pens, sign pens, plate pens, and the like. Thus, it can be widely used as a writing instrument such as a cap type and an in / out type.

Claims (8)

An oil-based ballpoint pen ink composition comprising at least a colorant, an organic solvent, and a dextrin carboxylic acid ester. The ink composition for oil-based ballpoint pens according to claim 1, wherein the dextrin carboxylic acid ester is a dextrin ester of a branched carboxylic acid and / or a dextrin ester of an aromatic carboxylic acid. 3. The oil-based ballpoint pen ink composition according to claim 1, wherein a content of the dextrin carboxylic acid ester is 0.5 to 10.0% by mass. The ink composition for oil-based ballpoint pens according to any one of claims 1 to 3, wherein the ink viscosity at 20 ° C and a shear rate of 5 sec ^-1 is 3000 mPa · s or more. The ink composition for oil-based ballpoint pens according to any one of claims 1 to 4, wherein the ink composition for oil-based ballpoint pens contains a polyvinyl butyral resin and / or a ketone resin. The ink composition for oil-based ballpoint pens according to any one of claims 1 to 5, wherein the organic solvent contains at least an aromatic glycol solvent. The oil-based ballpoint pen according to any one of claims 1 to 6, wherein a ballpoint pen tip holding a ball rotatably is attached to a tip portion of the ink containing cylinder directly or via a chip holder. The oil-based ballpoint pen according to any one of claims 1 to 6, characterized in that an oil-based ballpoint pen refill containing an ink composition for the ball and having a movement amount in the axial direction of the ball of 5 to 20 µm is disposed. . The oil-based ballpoint pen refill is a retractable oil-based ballpoint pen that is slidably disposed in a shaft cylinder, and a tip end portion of the ballpoint pen tip can be protruded and retracted from the tip end portion of the shaft cylinder. The oil-based ballpoint pen described in 1.