JP6959757B2 - Oil-based ballpoint pen - Google Patents

Description

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

Conventionally, in an ink composition for an oil-based ballpoint pen, in order to suppress ink leakage from the gap at the writing tip (ink leakage from the gap between the ball and the tip), a solvent having a vapor pressure of 0.001 mmHg or more at 25 ° C. is used. A technique for an ink composition for an oil-based ballpoint pen has been proposed, in which silica or terpenphenol resin is used as an ink leakage inhibitor, or an ink viscosity is set high by using a gelling agent.

As a technique using an alcohol, a polyhydric alcohol, or a glycol ether solvent having a vapor pressure of 0.001 mmHg or more at 25 ° C. as such an ink composition for an oil-based ballpoint pen, Japanese Patent Application Laid-Open No. 2004-107591 "Oil-based ballpoint pen" "Oil-based ink composition for oil" and "oil-based ink for ballpoint pens" published in JP-A-10-195365 using silica with a primary average particle size of 7 to 40 nm as a technique using an ink leakage inhibitor, and an OH value of 150 or more. As a technique using the terpene phenol resin, JP-A-2007-126528 “Oil-based ink for ballpoint pens”, and as a technique using hydrogenated castor oil or fatty acid amide wax as a shear reducing viscosity imparting agent, JP-A-P. It is disclosed in Japanese Patent Application Laid-Open No. 7-196972 "Oil-based ink composition for ballpoint pens".

"Japanese Patent Laid-Open No. 2004-107591" "Japanese Patent Laid-Open No. 10-195365" "Japanese Patent Laid-Open No. 2007-126528" "Japanese Patent Laid-Open No. 7-196972"

However, although Patent Document 1 has an effect of suppressing ink leakage to some extent, when the ink viscosity is lowered, ink leakage cannot be sufficiently suppressed only by the solvent used in Patent Document 1. Further, in Patent Document 2, in silica having a primary average particle diameter of 7 to 40 nm, the particle size is small and the specific gravity of silica is large, so that the dispersion stability in oil-based ink is inferior. In the terpene phenol resin having a value of 150 or more, since the OH value is high, the solubility in the oil-based ink is poor, and sufficient effects cannot be exhibited. Further, in Patent Document 4, although it is possible to suppress ink leakage to some extent with hydrogenated castor oil or fatty acid amide wax, the ink viscosity at rest becomes high, the ink followability tends to be inferior, and the brush strokes are blurred. It sometimes occurred, and had a problem that affected the writing quality.
In particular, when the ball diameter is 1.0 to 2.0 mm, the ballpoint pen tip is set so that the amount of ink ejected is large, so the effect of ink leakage is likely to occur, and writing when the writing tip is dry. Performance tends to be inferior.

More recently, in order to obtain a smooth brush feel, the viscosity of oil-based ink has been reduced, and the amount of ink ejected has increased accordingly, and ink leakage is likely to occur from the gap at the tip of the writing, which tends to cause a problem. ..

An object of the present invention is to obtain an ink composition for an oil-based ballpoint pen, which suppresses ink leakage and has good writing quality and writing performance, and an oil-based ballpoint pen using the same.

The present invention is to solve the above problems.
"1. An ink composition for an oil-based ballpoint pen containing a colorant, an organic solvent, and a shear thinning agent, wherein the shear thinning agent is a polyglycerin fatty acid ester.
2. The ink composition for an oil-based ballpoint pen according to Item 1, wherein the average degree of polymerization of polyglycerin constituting the polyglycerin fatty acid ester is in the range of 1 to 10.
3. 3. The ink composition for an oil-based ballpoint pen according to item 1 or 2, wherein the content of the shear thinning agent is 0.1 to 10.0% by mass with respect to the total amount of the ink composition. thing.
4. The ink composition for an oil-based ballpoint pen according to any one of items 1 to 3, wherein the HLB value of the polyglycerin fatty acid ester is in the range of 4 to 14.
5. The ink composition for an oil-based ballpoint pen according to any one of items 1 to 4, wherein the ink composition for an oil-based ballpoint pen further contains a polyvinyl butyral resin or a ketone resin.
6. The oil-based ballpoint pen ink composition according to any one of Items 1 to 5, wherein the oil-based ballpoint pen ink composition further contains a fatty acid ester (excluding polyglycerin fatty acid ester). ..
The ink composition for an oil-based ballpoint pen according to any one of Items 1 to 6, wherein the ink viscosity at 7.20 ° C. and a shear rate of 3.4 sec ^{-1 is 3000 to 30000 mPa · s.} ..
8. A ballpoint pen tip that rotatably holds a ball is provided at the tip of the ink containing cylinder, and the ink composition for an oil-based ballpoint pen according to any one of items 1 to 7 is placed in the ink containing cylinder. An oil-based ballpoint pen that is characterized by being housed. ".

The present invention contains polyglycerin fatty acid ester as a shear reducing viscosity imparting agent to increase the ink viscosity at rest, and ink leaks from the gap at the writing tip (ink from the gap between the ball and the tip). An oil-based ballpoint pen ink composition that suppresses leakage), lowers the ink viscosity during writing, improves the writing quality, and improves the writing performance when the writing tip is dry, and the oil-based ink using the same. I was able to get a ballpoint pen.

A feature of the present invention is that the ink composition for an oil-based ballpoint pen contains a polyglycerin fatty acid ester as a shear thinning agent.

(Polyglycerin fatty acid ester)
It was found that by containing the polyglycerin fatty acid ester in the ink composition for an oil-based ballpoint pen, it is possible to suppress ink leakage and maintain a good writing quality. This is because the polyglycerin fatty acid ester forms a three-dimensional structure in the ink, so that the ink viscosity at rest can be set high, and by suppressing the flow of the ink, the ink can be released from the gap between the ball and the tip of the chip. By forming a film when the writing tip is dried while suppressing bleeding, it is easy to suppress ink leakage from the gap between the writing tip (ink leakage from the gap between the ball and the tip). It was found that the inclusion of glycerin fatty acid ester makes it possible to keep the ink viscosity at the time of writing low and keep the writing quality good.
Further, the polyglycerin fatty acid ester can improve the writing performance by forming a film when the writing tip is dried, and when a pigment is used as a colorant, a pigment dispersion effect can be obtained, so that it is preferably used. can.

（式１）分子量＝７４ｍ＋１８
（式２）水酸基価＝５６１１０（ｍ＋２）／分子量
上記（式２）中の水酸基価とは、ポリグリセリンに含まれる水酸基数の大小の指標となる数値であり、１ｇのポリグリセリンに含まれる遊離ヒドロキシル基をアセチル化するために必要な酢酸を中和するのに要する水酸化カリウムのミリグラム数をいう。水酸化カリウムのミリグラム数は、社団法人日本油化学会編纂、「日本油化学会制定、基準油脂分析試験法（１）、１９９６年度版」に準じて算出される。 The polyglycerin fatty acid ester used in the present invention is represented by the following general formula (Chemical Formula 1). Regarding the average degree of polymerization (m) of polyglycerin constituting the polyglycerin fatty acid ester, considering that ink leakage is suppressed and the writing performance is improved, the average degree of polymerization is 10 or less and the molecular weight does not increase. The average degree of polymerization (m) is preferably in the range of 1 to 10, and the average degree of polymerization (m) is preferably in the range of 4 to 10 in consideration of further suppressing ink leakage. For example, the average degree of polymerization (m) is preferably in the range of 4 to 6. Examples of such polyglycerin fatty acid esters having an average degree of polymerization in the range of 1 to 10 include diglycerin fatty acid esters (average degree of polymerization (m): 2) and tetraglycerin fatty acid esters (average degree of polymerization (m): 4). ), Hexaglycerin fatty acid ester (average degree of polymerization (m): 6), decaglycerin fatty acid ester (average degree of polymerization (m): 10).
Here, the average degree of polymerization (m) is the average degree of polymerization (m) of polyglycerin calculated from the hydroxyl value by the end group analysis method. Specifically, the average degree of polymerization is calculated from the following equations (Equation 1) and (Equation 2).

(Equation 1) Molecular weight = 74m + 18
(Equation 2) Hydroxyl value = 56110 (m + 2) / molecular weight The hydroxyl value in the above (Equation 2) is a numerical value that is an index of the number of hydroxyl groups contained in polyglycerin, and is free contained in 1 g of polyglycerin. The number of milligrams of potassium hydroxide required to neutralize the acetic acid required to acetylate the hydroxyl group. The number of milligrams of potassium hydroxide is calculated according to the compilation of the Japan Oil Chemists'Association, "Established by the Japan Oil Chemists' Society, Standard Oil and Fat Analysis Test Method (1), 1996 Edition".

The fatty acid (fatty acid residue) constituting the polyglycerin fatty acid ester is selected from fatty acids having 8 to 22 carbon atoms. By forming a three-dimensional structure in the ink and increasing the viscosity of the ink at rest, The number of carbon atoms is preferably 14 to 20 in consideration of ink leakage suppression and writing performance, and more preferably 18 carbon atoms. Examples of such fatty acids having 8 to 22 carbon atoms include stearic acid, oleic acid, lauric acid, mistylic acid, caprylic acid, behenic acid, erucic acid, linoleic acid, condensed linoleic acid, and the like. It may be used in combination of two or more types depending on the purpose.

Among the fatty acids (fatty acid residues) that make up the polyglycerin fatty acid ester, by using stearic acid as the constituent fatty acid, a structure having a crystal structure is obtained, and the crystal structure is arranged to have a thickening effect due to a stable crystal structure. The more stable effect of suppressing ink leakage can be obtained, and the more stable crystal structure makes it easier for the formed film to soften when the tip of the writing is dried, and the writing performance is likely to improve. It is preferably an ester. Specific examples of the polyglycerin stearic acid ester include decaglycerin monostearic acid ester, decaglycerin tristearic acid ester, decaglycerin decastearic acid ester, hexaglycerin monostearic acid ester, hexaglycerin disstearic acid ester, and hexaglycerin tri. Examples thereof include stearic acid ester, hexaglycerin pentastearic acid ester, tetraglycerin monostearic acid ester, tetraglycerin tristearic acid ester, and tetraglycerin pentastearic acid ester, which have a stable crystal structure and more stable ink leakage suppression. The effect is obtained, and the film on the tip of the writing is easily softened. Considering the writing performance, hexaglycerin monostearic acid ester, hexaglycerin disstearic acid ester, hexaglycerin tristearic acid ester, tetraglycerin pentastearic acid. Esters are preferable, and more consideration is given, it is preferable to use hexaglycerin monostearic acid esters and hexaglycerin tristearic acid esters.

The HLB value of the polyglycerin fatty acid ester is preferably in the range of 4 to 14 in consideration of facilitating improvement of writing performance by forming a film when the writing tip is dried. This is because if the HLB value is less than 4, it is difficult to dissolve and stabilize in an organic solvent, and if the HLB value exceeds 14, the hydrophilicity is strong and moisture absorption into the ink is likely to occur. Therefore, the HLB value is 4. If it is out of the range of ~ 14, the stability over time of the ink is likely to be affected, and the effect of the present invention is difficult to obtain. Considering the above effects, the HLB value is preferably in the range of 4 to 12, and further considering, the HLB value is preferably in the range of 7 to 12.

The content of the polyglycerin fatty acid ester is preferably 0.1 to 10.0% by mass with respect to the total amount of the ink composition. If it is less than 0.1% by mass, the ink viscosity at rest is difficult to increase, and it is difficult to suppress ink leakage. If it exceeds 10.0% by mass, the ink viscosity becomes high, so that the writing quality and ink are improved. This is because the followability tends to be inferior. Further, in consideration of the above effect, 0.3 to 5.0% by mass is preferable, and if it exceeds 3.0% by mass, the writing performance is likely to be affected, so 0.3 to 3.0% by mass. % Is preferable.

The ink viscosity of the ink composition for an oil-based ball pen of the present invention is not particularly limited, but in the case of polyglycerin fatty acid ester, ^{the ink viscosity at 20 ° C. and a shear rate of 3.4 sec -1} (at rest) is 30,000 mPa. If it exceeds s, the writing performance, writing taste, and ink tracking performance tend to be inferior ^{. Therefore, the ink viscosity at 20 ° C. and a shear rate of 3.4 sec -1} (at rest) is preferably 30,000 mPa · s or less. Further, by setting the ink viscosity at 20 ° C. and a shear rate of 3.4 sec ^-1 (at rest) to 3000 mPa · s or more, the three-dimensional structure of the polyglycerin fatty acid ester causes ink leakage at the writing tip (ball and tip tip). The ink viscosity is preferably 3000 to 30000 mPa · s because it is easy to suppress ink leakage from the gaps between the two. Further, the ink viscosity is more preferably 3000 to 20000 mPa · s in consideration of further improving the writing performance and the ink following performance. Further, in a haunting type writing tool such as a knock type writing tool and a rotary feeding type writing tool, since it is necessary to further consider the suppression of ink leakage, 5000 to 20000 mPa · s is preferable. Therefore, in order to improve the writing performance, writing taste, ink following performance, and ink leakage suppression in a well-balanced manner, it is preferably set to 5000 to 20000 mPa · s.

Regarding the non-Newtonian viscosity index, the non-Newtonian viscosity index refers to "n" in the viscosity formula represented by S = αDn (however, 1>n> 0). S is the shear stress (dyne / cm ² ), D is the shear rate (s ^-1 ), and α is the non-Newtonian viscosity coefficient. When the non-Newtonian viscosity imparting index n is less than 0.55, the writing performance such as writing quality and ink followability tends to be inferior, and when n exceeds 0.90, ink leakage tends to occur. Therefore, it is preferable that the non-Newtonian viscosity imparting index n = 0.55 to 0.95. Considering the above effects, 0.65 to 0.92 is preferable, and 0.75 to 0.90 is more preferable.

(Colorant)
The colorant used in the present invention is not particularly limited, such as dyes and pigments, and can be appropriately selected and used. The combined use of dyes and pigments is preferable because the following effects can be easily obtained.
Examples of dyes include oil-soluble dyes, acidic dyes, basic dyes, gold-containing dyes, and various salt-forming type dyes such as salt-forming dyes of acidic dyes and basic dyes, organic acids and basic dyes. Types such as salt-forming dyes with and salt-forming dyes with acidic dyes and organic amines can be mentioned. These dyes may be used alone or in combination of two or more. As the dye, it is preferable to use at least a salt-forming dye in consideration of the stability over time due to compatibility with the polyglycerin fatty acid ester, and further, it should be considered that the stability over time can be maintained due to the stable salt-forming bond. For example, it is preferable to use a salt-forming dye of a basic dye and an organic acid, a salt-forming dye of a basic dye of an acidic dye, and a salt-forming dye of an acidic dye and an organic amine. Salt-forming dyes of dyes and organic acids are preferred. Further, regarding the organic acid constituting the salt-forming dye, if it is an organic acid having a phenylsulfon group, it is easy to form a lubricating film that is easily adsorbed on the metal, the lubricity is improved, and the writing taste and the wear of the ball seat are suppressed. Specific examples thereof include alkylbenzene sulfonic acid, naphthalene sulfonic acid, naphthalene sulfonic acid-formaldehyde condensate, alkyldiphenyl ether disulfonic acid, and polyoxyethylene alkyl phenyl ether phosphoric acid, which are stable for a long period of time in ink. In consideration of the above, it is preferable to use alkylbenzene sulfonic acid as the organic acid.
Specifically, regarding dyes, 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 1355, Bali First Red 1360, Bali First Yellow 1101, Bali First Yellow 1151, Nigrosin Base EXBP, Nigrosin Base EX, BASE OF BASIC DYES ROB-B, BASE OF BASIC DYES RO6GB, BASE OF BASIC DYES VPB-B, BASE OF BASIC DYES VB-B, BASE OF BASIC DYES MVB-3 (manufactured by Orient Chemical Industry Co., Ltd.), Eisenspiron Black GMH-Special, Eisenspiron Violet C-RH, Eisenspiron Blue GNH, Eisenspiron Blue 2BNH, Eisenspiron Blue C-RH, Eisenspiron Red C-GH, Eisenspiron Red C-BH, Eisenspiron Yellow C-GNH, Eisenspiron Yellow C-2GH, S.A. P. T. Blue 111, S.A. P. T. Blue GLSH-Special, S.M. P. T. Red 533, S.M. P. T. Orange 6, S.M. B. N. Violet 510, S.A. B. N. Yellow 530, S.A. R. C-BH (above, manufactured by Hodogaya Chemical Co., Ltd.) and the like can be mentioned.

Examples of pigments include inorganic, organic, and processed pigments. Specifically, carbon black, aniline black, ultramarine, yellow lead, titanium oxide, iron oxide, phthalocyanine, azo, quinacridone, and diketo Examples thereof include pyrrolopyrrole-based, quinophthalone-based, slene-based, triphenylmethane-based, perinone-based, perylene-based, dioxazine-based, metallic pigments, pearl pigments, fluorescent pigments, phosphorescent pigments and the like.

It is preferable to use a pigment as the colorant. In the case of a ballpoint pen, a pigment particle causes a physical obstacle in the gap between the ball and the inner wall of the tip tip to suppress ink leakage. This is because it is easy to do. Further, in the present invention, by using the polyglycerin fatty acid ester, a higher ink leakage suppressing effect can be obtained by forming a film on the tip of the writing and acting synergistically due to physical damage of the pigment. At the same time, a pigment dispersion effect can be obtained, which is preferable. Further, the pigment is preferable because it has excellent handwriting fastness and particularly excellent light resistance.
Furthermore, by using a pigment, in the case of a ballpoint pen, the pigment particles enter the gap between the ball and the tip body, which makes it easier for the action like a bearing to work, and by suppressing metal contact, the lubricity is improved. It is preferable to use a pigment because it is easy to obtain the effect of improving the writing quality and suppressing the wear of the ball seat. Further, the average secondary particle size is preferably 1 to 500 nm in consideration of the gap relationship inside the ballpoint pen tip. It is more preferably 10 to 350 nm, and even more preferably 50 to 300 nm. As in the present invention, it is preferable to use a pigment because the writing quality can be improved by lowering the viscosity of the ink by using a polyglycerin fatty acid ester.
Here, the average particle size is the particle size at 50% of the cumulative volume of the particle size distribution measured by the laser diffraction method using a laser diffraction type particle size distribution measuring machine (trade name "Microtrac HRA9320-X100", Nikkiso Co., Ltd.). It can be measured by D50).

The type of pigment is preferably carbon black, quinacridone-based, slene-based, or diketopyrrolopyrrole-based pigment in consideration of lubricity.

The content of the colorant is preferably 5.0 to 30.0% by mass with respect to the total amount of the ink composition. This is because if it is less than 5.0% by mass, it tends to be difficult to obtain a dark stroke, and if it exceeds 30.0% by mass, it tends to affect the solubility in ink. In consideration, it is preferably 7.0 to 25.0% by mass, and further considered, it is 10.0 to 25.0% by mass.

(Organic solvent)
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, and 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 and ethanol. , 1-propanol, 2-propanol, isopropanol, isobutanol, t-butanol, propagil alcohol, allyl alcohol, 3-methyl-1-butin-3-ol, ethylene glycol monomethyl ether acetate and other higher alcohols. Examples thereof include organic solvents generally used as inks for oil-based ball pens, such as alcohol solvents.

Among these organic solvents, considering the solubility with polyglycerin fatty acid ester, it is preferable to use a water-insoluble organic solvent to prepare an ink composition for an oil-based ballpoint pen, and among them, a glycol ether solvent is used. Is preferable. This is because when a glycol ether solvent is used, it easily absorbs moisture, so that the strength of the film formed when the tip of the chip dries is softened and the writing performance is easily improved. When used in combination with the polyglycerin fatty acid ester, it is easy to improve. It is preferable to use an aromatic glycol ether solvent because it is more effective and the stability in the ink is taken into consideration. Further, as an organic solvent other than the glycol ether solvent, it is preferable to use an alcohol solvent, which means that the alcohol solvent volatilizes, is easily dried at the tip of the chip, and contains a polyglycerin fatty acid ester. By thickening the inside of the writing tip (inside the tip of the tip) more locally, ink leakage (ink leakage from the gap between the ball and the tip of the tip) is suppressed from the gap of the writing tip, and the ink leakage suppression performance is improved. This is preferable. Further, aromatic alcohols such as benzyl alcohol also have an effect of improving lubricity, and therefore it is preferable to use at least.

Regarding the organic solvent, when the content of the alcohol solvent with respect to the total amount of the ink composition is X and the content of the glycol ether solvent with respect to the total amount of the ink composition is Y, the relationship is 0.01 ≦ X / Y ≦ 3. Is preferable. This is preferably X / Y ≦ 3 because too much alcohol solvent tends to affect the writing performance, while too much glycol ether solvent absorbs too much water and the resin film becomes soft and the ink This is because 0.01 ≦ X / Y is preferable because it easily affects the hanging performance and the stability of the ink over time. Further, considering that the writing performance is improved by the synergistic effect of the polyglycerin fatty acid ester and the phosphoric acid ester-based surfactant used in the present invention, 0.1 ≦ X / Y ≦ 2 is preferable, and the writing performance is further improved. In consideration, 0.1 ≦ X / Y ≦ 1 is preferable.

Further, the content of the organic solvent is preferably 10.0 to 90.0% by mass, and is dried at the tip of the chip, in consideration of improving solubility, brush dryness, bleeding, etc. Considering the property, it is preferably 20.0 to 90.0% by mass, more preferably 40.0 to 70.0% by mass.

(resin)
Further, in order to further improve the suppression of ink leakage, it is preferable to use a resin as an ink viscosity modifier. As the resin, polyvinyl butyral resin, ketone resin, polyacetal resin, polyvinyl alcohol resin, cellulose resin, terpene resin, etc. Examples thereof include alkyd resin, phenoxy resin and polyvinyl acetate resin, and among them, polyvinyl butyral resin or ketone resin is preferably contained. This is because the ink leakage suppressing effect is more likely to be improved. In particular, the ketone resin can be synergistically expected to have a higher ink leakage suppressing effect when used in combination with the polyglycerin fatty acid ester, and further suppresses crying. This is because it has the effect of
Furthermore, when the ball diameter is made larger than usual to 1.0 mm to 2.0 mm, the amount of ink ejected becomes large, and crying and sticking due to excess ink are likely to occur at the tip of the chip, and a ketone resin is used. As a result, it is easy to suppress crying and sticking by suppressing the ink from rising, so that it is preferable, and when it is set to 1.2 mm to 2.0 mm, it is more effective. Furthermore, considering the suppression of crying and botting, among the ketone resins, among the ketone resins, an aromatic ring skeleton (having a benzene ring such as a phenyl group, an acetophenone group, and a naphthalene group) and a cyclohexane skeleton (having a cyclohexane ring such as a cyclohexane group and a cyclohexanone group), etc. It is preferable to use a ketone resin having the cyclic structure of.

Further, considering the effect of suppressing ink leakage and improving the writing quality, it is most preferable to use polyvinyl butyral resin. This is because when the polyglycerin fatty acid ester and the polyvinyl butyral resin are used in combination, the film formed makes it easier to improve ink leakage, and the polyvinyl butyral resin always has elasticity between the balls and the ball seat. This is because the ink layer having a property is formed to make it difficult to make direct contact with the ink layer, so that the writing quality can be improved. When a pigment is used as the colorant, a polyvinyl butyral resin is preferably used because a pigment dispersion effect can be obtained. In particular, when the polyglycerin fatty acid ester used in the present invention and the polyvinyl butyral resin are used in combination, a high ink leakage suppressing effect can be obtained, which is more preferable.
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.
In particular, when the ball diameter is made larger than usual to 1.0 mm to 2.0 mm, the influence of ink leakage is likely to occur from the gap between the ballpoint pen tip body and the ball, so it is effective to use polyvinyl butyral resin. Therefore, it is more effective when the polyglycerin fatty acid ester used in the present invention and the polyvinyl butyral resin are used in combination, and particularly when the thickness is 1.2 mm to 2.0 mm.

The polyvinyl butyral resin preferably has a hydroxyl group content of 25 mol% or more. This is because polyvinyl butyral resin with a hydroxyl group content of less than 25 mol does not have sufficient solubility in an organic solvent, and it is difficult to obtain a sufficient lubricating effect and an effect of suppressing ink leakage. Furthermore, considering the writing performance due to moisture absorption. This is because it is preferable to use a polyvinyl butyral resin having a hydroxyl group content of 25 mol% or more. Further, the polyvinyl butyral resin having a hydroxyl group content of 30 mol% or more is preferable because the writing taste is easily improved. This is because at the time of writing, frictional heat is generated by the rotation of the ball, which warms the ink at the tip of the chip and raises the temperature of the ink, but the polyvinyl butyral resin is different from other resins. Even if the ink temperature rises, it has the property of making it difficult for the ink viscosity to decrease, and an elastic ink layer is always formed between the ball and the ball seat to make it difficult to make direct contact, improving the writing quality. It tends to be easy. In particular, oil-based ballpoint pens are effective because they often write with high writing pressure. Further, when a polyvinyl butyral resin having a hydroxyl group content of more than 40 mol% is used, the amount of moisture absorbed tends to increase and the stability with time 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 preferable. Therefore, a polyvinyl butyral resin having a hydroxyl group content of 30 to 40 mol% is preferable, and a hydroxyl group content of 30 to 36 mol% is more preferable.
The amount of hydroxyl groups (mol%) of the polyvinyl butyral resin is the content of hydroxyl groups (mol%) with respect to the total amount of mol of butyral groups (mol%), acetyl groups (mol%), and hydroxyl groups (mol%). It shows the rate.

Regarding the average degree of polymerization of the polyvinyl butyral resin, when the average degree of polymerization is 200 or more, the ink leakage suppression performance is likely to be improved, and when 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 the writing taste. Further, considering the suppression of ink leakage, the average degree of polymerization is preferably 1500 or less. Here, the average degree of polymerization refers to the number of basic units constituting one molecule of polyvinyl butyral resin, and a value measured based on the method specified in JIS K6728 (2001 version) can be adopted. ..

Specifically, the polyvinyl butyral resin is a trade name manufactured by Sekisui Chemical Industry Co., Ltd .; Eslek BH-3 (hydroxyl amount: 34 mol%, average degree of polymerization: 1700), BH-6 (hydroxyl amount: 30 mol%). , Average degree of polymerization: 1300), BX-1 (hydroxyl amount: 33 ± 3 mol%, average degree of polymerization: 1700), BX-5 (hydroxyl amount: 33 ± 3 mol%, average degree of polymerization: 2400), BM -1 (Amount of hydroxyl groups: 34 mol%, average degree of polymerization: 650), BM-2 (Amount of hydroxyl groups: 31 mol%, average degree of polymerization: 800), BM-5 (Amount of hydroxyl groups: 34 mol%, average degree of polymerization: 850) ), BL-1 (Amount of hydroxyl groups: 36 mol%, average degree of polymerization: 300), BL-1H (Amount of hydroxyl groups: 30 mol%), BL-2 (Amount of hydroxyl groups: 36 mol%, average degree of polymerization: 450), BL-2H (hydroxyl amount: 29 mol%), BL-10 (hydroxyl amount: 28 mol%), etc., and trade name manufactured by Kuraray Co., Ltd .; Mobital B20H (hydroxyl amount: 26 to 31 mol%, average degree of polymerization: 250-500), B30T (amount of hydroxyl groups: 33-38 mol%, average degree of polymerization: 400-650), B30H (amount of hydroxyl groups: 26-31 mol%, average degree of polymerization: 400-650), B30HH (amount of hydroxyl groups) : 30-34 mol%, average degree of polymerization: 400-650), B45H (hydroxyl amount: 26-31 mol%, average degree of polymerization: 600-850), B60T (hydroxyl amount: 34-38 mol%, average degree of polymerization: 750 to 1000), B60H (amount of hydroxyl groups: 26 to 31 mol%, average degree of polymerization: 750 to 1000), B75H (amount of hydroxyl groups: 26 to 31 mol%, average degree of polymerization: 1500 to 1750) and the like. These may be used alone or in mixture of 2 or more types.

If the total content of the resin is less than 1.0% by mass with respect to the total amount of the ink composition, the amount of resin film formed may be insufficient, and the ink leakage suppression performance tends to be inferior, exceeding 40.0% by mass. As a result, the solubility in the ink tends to be inferior, so 1.0 to 40.0% by mass is preferable with respect to the total amount of the ink composition. Further, considering the ink leakage suppression performance, 5.0% by mass or more is preferable, and if it exceeds 30.0% by mass, the ink viscosity tends to be too high and the writing quality and writing performance tend to be affected. 0 to 30.0% by mass is preferable.

In addition, when polyglycerin fatty acid ester is contained as in the present invention, polyvinyl butyral resin and ketone resin are used in combination in order to suppress ink leakage and improve writing quality, writing performance, and crying. Is preferable. Furthermore, in order to suppress ink leakage and achieve a good balance between writing taste, writing performance, and crying, the content of polyvinyl butyral resin with respect to the total amount of ink composition is M, and the content of ketone resin with respect to the total amount of ink composition. When L is, it is preferable that the relationship is 0.01 ≦ M / L ≦ 3, and if ink leakage is further suppressed and the writing taste and writing performance are taken into consideration, the relationship is 0.1 ≦ M / L ≦ 1. Is preferable, and more preferably, 0.1 ≦ M / L ≦ 0.8.

As the resin other than the polyvinyl butyral resin and the ketone resin, a spinnability imparting agent may be appropriately used. In particular, it is preferable to contain the polyvinylpyrrolidone resin because the binding property of the ink is enhanced and the generation of excess ink at the tip of the chip is easily suppressed by blending the polyvinylpyrrolidone resin. If the content of the polyvinylpyrrolidone resin is less than 0.01% by mass with respect to the total amount of the ink composition, it tends to be difficult to suppress the generation of excess ink. Therefore, if it exceeds 3.0% by mass, it is contained in the ink. Since the solubility tends to be inferior, 0.01 to 3.0% by mass is preferable with respect to the total amount of the ink composition. Considering the above reasons, 0.1 to 2.0% by mass is preferable. Specific examples thereof include trade names manufactured by ASP Japan Co., Ltd .; PVP K-15, PVP K-30, PVP K-90, PVP K-120 and the like. These may be used alone or in mixture of 2 or more types.

Further, in order to further improve writing performance and lubricity, it is preferable to further contain a fatty acid ester (excluding polyglycerin fatty acid ester). It is possible to improve writing performance and writing quality by using polyglycerin fatty acid ester, but in particular, by using fatty acid ester (excluding polyglycerin fatty acid ester), writing tip for a longer time It is possible to improve good writing performance (long-time writing performance) even when the part is dried. Among the fatty acid esters (excluding polyglycerin fatty acid esters), it is preferable to use a fatty acid ester having a branched alkyl group in consideration of improving the writing performance for a long period of time. This is because the fatty acid ester having a branched alkyl group has a bulkier structure than the linear structure, so that the bulkiness of the branched alkyl group increases the film strength formed when the tip of the chip is dried with ink. It is more effective because it is easy to soften, it is easy to improve the writing performance, and it has a bulky structure, so that a thick lubricating film is formed and the lubricity is easily improved.

Fatty acid esters (excluding polyglycerin fatty acid esters) are obtained by esterifying fatty acids with alcohols such as monohydric alcohols and polyhydric alcohols. Further, the acid value of the fatty acid ester is preferably 0.01 to 5 (mgKOH / g), which is compatible with the polyglycerin fatty acid ester in the oil-based ink and other components, and is a long-term ink. This is because it is stable inside, so that it is possible to improve the writing performance for a long period of time, improve the lubricity for a long period of time, and easily improve the writing quality. With more consideration, the acid value is preferably 0.01 to 2.5 (mgKOH / g), more preferably 0.05 to 1.0 (mgKOH / g).
The acid value is expressed in mg of potassium hydroxide required to neutralize the acidic component (free fatty acid) contained in 1 g of the sample.

The alcohol used in the esterification reaction of the fatty acid ester (excluding polyglycerin fatty acid ester) is preferably a polyhydric alcohol. This is because when the fatty acid ester has a large number of hydroxyl groups, a moisture absorbing action works, the strength of the film formed when the tip of the chip dries is softened, and the effect of smoothing the rotation of the ball can be obtained. It is presumed that the writing performance will be improved without occurring. Considering that the writing performance is further improved, it is preferable to use a polyhydric alcohol having a hydroxyl group having a hydroxyl group of 4 or more, and more preferably a hydroxyl group having a hydroxyl group of 5 or more. Further, if the number of hydroxyl groups is too large, the stability in the oil-based ink is likely to be affected, so that the number of hydroxyl groups is preferably octavalent or less.

Specific examples of the alcohol used in the esterification reaction of the fatty acid ester include pentanol, cyclohexanol, hexanol, heptanol, octanol, 2-ethylhexanol, nonanol, isononanol, decanol, lauryl alcohol, and mi. Examples thereof include styryl alcohol, stearyl alcohol and docosanol. Polyhydric alcohols include ethylene glycol, propylene glycol, polyalkylene glycol, 1,3-propanediol, diethylene glycol, glycerin, 2-methylpropanetriol, neopentyl glycol, trimethylolethane, trimethylolethane, trimethylolpropane, and penta. Examples thereof include erythritol, dipentaerythritol, and tripentaerythritol. Among these, it is preferable to contain a fatty acid ester esterified with pentaerythritol such as pentaerythritol, dipentaerythritol, and tripentaerythritol in order to further improve the writing performance and consider the stability over time of the ink. For example, it preferably contains a fatty acid ester esterified with dipentaerythritol.

Specific examples of the fatty acids used in the esterification reaction of the fatty acid ester include valerate, isovaleric acid, caproic acid, 2-ethylbutanoic acid, heptanic acid, 2-methylhexanoic acid and 3 as monocarboxylic acids. -Methylhexanoic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, isoheptanic acid, capric acid, 2-ethylhexanoic acid, nonanoic acid, 3,5,5-trimethylhexanoic acid, neononanoic acid, capric acid, neodecanoic acid , Lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, araquinic acid and the like. Specific examples of the polyvalent carboxylic acid include succinic acid, glutanic acid, adipic acid, sebacic acid, ufutaric acid, isophthalic acid, fumaric acid, maleic acid, trimellitic acid, and pyromellitic acid.

The content of the fatty acid ester is more preferably 0.1 to 10.0% by mass with respect to the total amount of the ink composition. This is because if it is less than 0.1% by mass, it tends to be difficult to obtain the desired writing performance, and if it exceeds 10.0% by mass, the ink aging tends to become unstable. Considering the above, 0.1 to 8.0% by mass is preferable, and more considering, 0.1 to 5.0% by mass is most preferable.

(Surfactant)
In the present invention, it is preferable to use a phosphoric acid ester-based surfactant or a fatty acid in consideration of improving the writing performance. This is because the use of phosphate ester surfactants or fatty acids tends to soften the film formed and may improve writing performance. Among them, the number of carbon atoms contained in the alkyl group of the phosphoric acid ester-based surfactant or fatty acid is preferably 10 to 20, and more preferably, the number of carbon atoms is 12 to 18. Further, considering the lubricity (high load performance) under a high writing pressure (300 to 500 gf), it is preferable to use a phosphate ester-based surfactant, which is a high writing pressure (300) in the case of a ballpoint pen. Even at ~ 500 gf), the lubricity between the ball and the chip body is improved to suppress wear of the ball seat, and it is easy to obtain a good handwriting without blurring, so that it can be used more preferably in the present invention. ..

Examples of the phosphoric acid ester-based surfactant include a phosphoric acid monoester of a polyoxyethylene alkyl ether or a polyoxyethylene alkyl aryl ether, a phosphoric acid diester of a polyoxyethylene alkyl ether or a polyoxyethylene alkyl aryl ether, and a polyoxyethylene alkyl ether. Alternatively, a phosphoric acid triester of a polyoxyethylene alkylaryl ether, an alkyl phosphoric acid ester, an alkyl ether phosphoric acid ester or a derivative thereof and the like can be mentioned, and the alkyl group of the phosphoric acid ester-based surfactant is a styrene phenol-based or nonylphenol. Examples include systems, lauryl alcohol-based, tridecyl alcohol-based, and octylphenol-based. Examples of the fatty acid include oleic acid, stearic acid, linoleic acid and the like, and these phosphoric acid ester-based surfactants or fatty acids may be used alone or in combination of two or more. Among them, in consideration of lubricity (high load performance) under high writing pressure (300 to 500 gf), it is preferable to use a phosphoric acid ester-based surfactant, and in particular, the number of carbon atoms contained in the alkyl group is 5 to 5. It is preferably 18, and if further considered, the number of carbon atoms is more preferably 10 to 18, and more preferably, the number of carbon atoms is 12 to 18. It should be noted that if the number of carbon atoms of the alkyl group is excessively small, the lubricity tends to be insufficient, and if the number of carbon atoms is excessively large, the stability of the ink with time tends to be affected.
Further, the acid value of the phosphate ester-based surfactant is preferably 200 or less, which is the lubricity (high load performance) of the phosphate ester-based surfactant under high writing pressure (300 to 500 gf). The acid value is preferably 30 to 200, and more preferably 70 to 200, in consideration of stability in ink and lubricity.
The acid value is expressed in mg of potassium hydroxide required to neutralize the acidic component contained in 1 g of the sample.

The content of the phosphoric acid 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, it tends to be difficult to obtain the desired lubricity, and if it exceeds 5.0% by mass, the ink tends to become unstable over time. In consideration of the above, 0.3 to 3.0% by mass is preferable, and 0.5 to 3.0% by mass is most preferable with respect to the total amount of the ink composition.

Specific examples of the phosphoric acid ester-based surfactant include Plysurf A217E (alkyl group: 14 carbon atoms, acid value: 45 to 58) and A219B from the Plysurf series (Daiichi Kogyo Seiyaku Co., Ltd.). (Alkyl group: 12 carbon atoms, acid value: 44 to 58), A215C (alkyl group: 12 carbon atoms, acid value: 80 to 95), A208B (alkyl group: 12 carbon atoms, acid value: 135 to 155) ), A208N (alkyl group: mixture of 12 and 13 carbon atoms, acid value: 160 to 185), phospanol series (manufactured by Toho Kagaku Kogyo Co., Ltd.), phospanol RB410 (alkyl group: carbon) Number 18, acid value: 80 to 90), RS-610 (alkyl group: 13 carbons, acid value: 75 to 90), RS-710 (alkyl group: 13 carbons, acid value: 55 to 75) And so on. These surfactants may be used alone or in combination of two or more.

(Organic amine)
In the present invention, it is preferable to use an organic amine in consideration of the stability of the ink component in the ink. Amines having ethylene oxide such as oxyethylenealkylamine and polyoxyethylenealkylamine, alkylamines such as laurylamine and stearylamine, dimethylalkylamines such as distearylamine, dimethyllaurylamine, dimethylstearylamine and dimethyloctylamine, etc. Among them, amines having ethylene oxide and dimethylalkylamines are preferable in consideration of stability in ink, and dimethylalkylamines are preferable in further consideration. In particular, when a phosphoric acid ester-based surfactant is used, it is preferable because it is neutralized and stabilized in the ink, so that the effect of improving the writing performance and the writing taste can be easily obtained.

Regarding the reactivity of the organic amine with other components in the ink, the primary amine is the strongest, followed by the secondary amine and the tertiary amine, and the reactivity is smaller. It is preferable to use a secondary amine or a tertiary amine. These may be used alone or in mixture of 2 or more types.

Further, the total amine value of the organic amine is preferably 100 to 300 (mgKOH / g) in consideration of stability with dyes and other ink components. When it exceeds 300 (mgKOH / g), the reactivity is strong, so that it easily reacts with the dye and other ink components, and thus the ink stability with time tends to be inferior. Further, when the total amine value is less than 100 (mgKOH / g), the stability of the components in the ink is likely to be affected, and further, the neutralization with respect to the phosphoric acid ester-based surfactant becomes insufficient. The stability of the ink over time is likely to be affected, and when an oil-based ballpoint pen is used, the adsorptivity of metals such as balls and chip bodies tends to be inferior, and it is difficult to obtain lubrication performance. The range of 150 to 300 (mgKOH / g) is preferable in consideration of stability and lubricity with dyes and phosphoric acid ester-based surfactants, and 200 to 300 (mgKOH / g) in consideration of more. Is preferable.
The total amine value indicates the total amount of primary, secondary and tertiary amines, and is represented by the number of mg of potassium hydroxide equivalent to hydrochloric acid required to neutralize 1 g of the sample.

Specific examples of organic amines include oxyethylene alkylamines, and specific examples of polyoxyethylene alkylamines include nymine L-201 (total amine value: 232-246, secondary amines) and L-202. (Total amine value: 192 to 212, tertiary amine), L-207 (total amine value: 107 to 119, tertiary amine), S-202 (total amine value: 152 to 166, tertiary amine), S-204 (total amine value: 120 to 134, tertiary amine), S-210 (total amine value: 75 to 85, tertiary amine), DT-203 (total amine value: 227 to 247, 3, Grade amines), DT-208 (total amine value: 146 to 180, tertiary amines) (manufactured by Nippon Oil & Fats Co., Ltd.) and the like. Specific examples of the alkylamine include fermin 80 (total amine value: 204 to 210, primary amine), fermin D86 (total amine value: 110-119, secondary amine), and fermin DM2098 (total amine value: 254). ~ 265, tertiary amine), Farmin DM8680 (total amine value: 186 to 197, tertiary amine) (Kao Co., Ltd.), Nissan tertiary amine BB (total amine value: 243-263, tertiary amine), same FB (total amine value: 230 to 250, tertiary amine) (manufactured by Nippon Oil & Fats Co., Ltd.) and the like can be mentioned. These may be used alone or in mixture of 2 or more types.

The content of the organic amine is preferably 0.1 to 10.0% by mass with respect to the total amount of the ink composition in consideration of stability with the salt-forming dye and other components, and phosphoric acid described later. Considering neutralization with respect to the ester-based surfactant, 0.1 to 5.0% by mass is preferable.

Further, in the present invention, it is preferable that the cyclic phosphorus compound of the following general formula (Chemical Formula 2) is contained, which means that when the writing tip is dried, the ink is locally thickened at the writing tip to form a film. This is because it is possible to suppress ink leakage from the writing tip. In particular, the combined use of the cyclic phosphorus compound of the general formula (Chemical Formula 2) and the polyglycerin fatty acid ester is effective because it is easy to synergistically suppress ink leakage. In particular, in the case of a haunting type writing tool such as a knock type writing tool or a rotary feeding type writing tool, it is necessary to further consider the suppression of ink leakage, which is preferable.

The cyclic phosphorus compound is a compound having a cyclic structure containing a phosphorus element, but when the writing tip is dried, a film is formed on the writing tip by a polymer of the styrene compound of the cyclic phosphorus compound. It is possible to suppress ink leakage from the writing tip, but at the same time, by performing an ink thickening action, it is possible to suppress ink leakage synergistically. Further, when the O atom adjacent to the P atom of the cyclic phosphorus is adsorbed on the writing tip portion, the cyclic phosphorus compound is likely to remain, and a higher ink leakage suppressing effect can be obtained. In particular, in the case of a ballpoint pen, if the ball and the chip body are made of metals, the O atom adjacent to the P atom is easily adsorbed on the writing tip, which is effective. Further, the cyclic phosphorus compound of the general formula (Chemical Formula 2) can improve the writing performance due to the film formed when the writing tip is dried, and when a pigment is used as a colorant, a pigment dispersion effect can be obtained. It can be preferably used.

The weight average molecular weight of the cyclic phosphorus compound is preferably 2000 or less. This is because when the weight average molecular weight exceeds 2000, it is difficult to dissolve and stabilize in an oil-based ink, so that the effect of the present invention is difficult to obtain. Furthermore, when the writing tip is dried, the ink is locally applied to the writing tip. Since it is too thick, it tends to affect the writing performance. Considering the above effects, the weight average molecular weight is preferably 1000 or less.

Regarding the general formula (Chemical formula 1) of the cyclic phosphorus compound, it is preferable to set m = 1 to 5, which means that when m exceeds 5, the molecular weight tends to increase, and as described above, in the oil-based ink. Since it is difficult to dissolve and stabilize the ink, it is difficult to obtain the effect of the present invention. Considering more, it is preferable to set m = 1 to 3.

Further, in the ink composition for writing utensils according to the present invention, as other additives, in order to improve lubricity and ink stability over time, (i) surfactants such as fluorine-based surfactants and silicone-based surfactants are used. Agents, fatty acid alkanolamides, anionic surfactants, cationic surfactants, amphoteric surfactants, and salt-forming compounds of anionic surfactants and / or cationic surfactants, (ii). Pseudoplasticizers such as viscosity modifiers such as fatty acid amide, hydrogenated castor oil, and (iii) colorant stabilizers, (iv) plasticizers, (v) chelating agents, or (vi) water as an auxiliary solvent. Etc. may be used as appropriate. These may be used alone or in combination of two or more.

The amount of movement of the ball of the ballpoint pen tip used in the present invention in the vertical axis direction is not particularly limited, but if the amount of movement of the ball in the vertical axis direction is large, ink leaks from the gap between the ballpoint pen tip body and the ball. Furthermore, since the writing performance tends to be inferior when the writing tip is dried, if the amount of movement of the ball in the vertical axis direction is made larger than usual and is 10 μm or more, the amount of ink ejected increases. It is easy to obtain the ink, and it is effective to use the polyglycerin fatty acid ester used in the present invention, and it is particularly remarkable and more effective when the thickness is 12 μm or more. On the other hand, if the amount of movement of the ball in the vertical axis direction exceeds 30 μm and is too large, ink leakage suppression tends to be inferior. Therefore, 30 μm or less is preferable, and more consideration is given, 25 μm or less is preferable.

The arithmetic mean roughness (Ra) of the ball surface of the ballpoint pen tip used in the present invention is preferably 0.1 to 12 nm. This is because if the arithmetic average roughness (Ra) is less than 0.1 nm, it is difficult for ink to be sufficiently applied to the ball surface, it is difficult to obtain a dark handwriting when writing, and lines are likely to be skipped and blurring is likely to occur in the handwriting. If the roughness (Ra) exceeds 12 nm, the surface of the ball is too rough and the rotation resistance between the ball and the ball seat is large, so that the writing quality tends to be inferior. This is because it is easy to affect. Further, when the arithmetic mean roughness (Ra) is 0.1 to 10 nm, the ink is easily placed on the ball surface, which is more preferable, and more preferably 2 to 8 nm. The surface roughness can be measured by (model name SPI3800N manufactured by Seiko Epson Corporation).

The material used for the balls is not particularly limited, but is limited to cemented carbide balls containing tungsten carbide as a main component, metal balls such as stainless steel, and ceramics such as silicon carbide, silicon nitride, alumina, silica, and zirconia. Examples include balls and ruby balls.
The diameter of the ball is not particularly limited, but if the diameter of the ball is large, ink tends to leak from the gap between the ballpoint pen tip body and the ball, and the writing performance tends to be inferior when the writing tip is dried. When the diameter is 1.0 mm to 2.0 mm, which is larger than usual, the effect is likely to occur, and it is effective to use the polyglycerin fatty acid ester used in the present invention, particularly 1.2 mm to 2.0 mm. The case is noticeable and more effective.

The ink consumption per 100 m is preferably 10 to 120 mg. This is because if the ink consumption per 100 m is less than 10 mg, it is difficult to obtain dark handwriting and good writing quality, and if the ink consumption per 100 m exceeds 120 mg, ink leaks from the gap between the ball and the tip of the chip. This is because writing performance and crying are likely to occur.
When the ball diameter is made larger than usual to 1.0 to 2.0 mm, as described above, 100 m in consideration of dark handwriting, ink leakage suppression, writing taste, writing performance, crying bottom, etc. The amount of ink consumed per ink is preferably 20 to 110 mg, and when the ball diameter is 1.2 to 1.6 mm, it is preferably 30 to 100 mg.
Regarding the amount of ink consumed, spiral using 5 test samples at a writing speed of 4 m / min under the conditions of 20 ° C, writing paper JIS P3201 writing paper, writing angle 70 °, and writing load 200 g. A written test is performed, and the average value of the ink consumption per 100 m is defined as the ink consumption per 100 m.

The material of the ball pen tip includes metal materials such as stainless steel, nickel silver, brass (brass), aluminum bronze and aluminum, and resin materials such as polycarbonate, polyacetal and ABS. A nickel silver chip body is preferable in consideration of properties, and a stainless steel chip body is preferable in consideration of wear of the ball seat and stability over time.

As the ink container used in the present invention, there are restrictions on the materials that can be used from the viewpoints of chemical resistance, moisture permeability, air permeability, and the like. In that respect, it is conventionally preferable to use polypropylene as a material. However, when the polyvinyl butyral resin is used in the present invention, it has a very strong affinity with the polypropylene ink storage cylinder, and when the ink moves in the ink storage cylinder, the ink easily adheres to the inner wall, and the remaining amount of ink can be known. It's hard. Therefore, when polypropylene is used as the ink containing cylinder, it is preferable to treat the inner wall of the ink containing cylinder with a surfactant. By applying the surfactant to the inner wall of the ink storage cylinder, the polypropylene, which is the material of the storage cylinder, and the ink do not come into direct contact with each other, and the relationship in which the surfactant is interposed is maintained and the ink moves. It is possible to prevent the ink from adhering to the inner wall of the ink storage cylinder. Examples of the surfactant include silicone-based surfactants and fluorine-based surfactants. Considering the prevention of adhesion to the inner wall of the ink storage cylinder, silicone-based surfactants and fluorine-based surfactants are preferable, and more. Considering this, a silicone-based surfactant is preferable.

Examples of the material of the silicone-based surfactant include dimethyl silicone, methyl phenyl silicone, methyl hydrogen silicone, alkyl aralkyl silicone, polyether silicone, high fatty acid ester fatty acid silicone, etc. Among them, excellent adhesion prevention property and non-reaction. Since it is property, alkyl aralkyl silicone is preferable in consideration of stability with respect to oil-based ink components. The most effective method of application is to apply evenly to the inner wall at the same time during extrusion molding.

Example 1
The ink composition for an oil-based ball pen of Example 1 has a dye and a pigment as a colorant, a benzyl alcohol as an organic solvent, an ethylene glycol monophenyl ether, a polyglycerin fatty acid ester, and a polyvinyl butyral resin, a ketone resin, and a branched chain as a resin. A fatty acid ester having an alkyl group, a phosphoric acid ester-based surfactant as a surfactant, oxyethylene alkylamine as an organic amine, and polyvinylpyrrolidone as a spinnability-imparting agent are used, and a predetermined amount is weighed and weighed at 60 ° C. After heating to the ester, the ink composition for writing utensils was obtained by completely dissolving the ink composition using a disperser stirrer. The specific blending amount is as follows. When the ink viscosity of Example 1 was measured using a viscometer Viscometer RVDVII + Pro CP-52 spindle manufactured by Brookfield Co., Ltd., the shear rate was 0.18 sec ^-1 and the ink viscosity was 20950 mPa in an environment of 20 ° C. In an environment of s and 20 ° C., the shear rate was 3.4 sec ^-1 and the ink viscosity was 14070 mPa · s. The non-Newtonian viscosity imparting index n was 0.86.

Example 1 (ink blending)
Coloring agent (dye, salt-forming dye of basic dye and acid dye) 10.0% by mass
Colorant (dye, acid dye and amine salt-forming dye) 5.0% by mass
Colorant (slen pigment) 5.0% by mass
Organic solvent (benzyl alcohol) 20.0% by mass
Organic solvent (ethylene glycol monophenyl ether) 34.0% by mass
Polyglycerin fatty acid ester (hexaglycerin tristearic acid ester)
0.5% by mass
Fatty acid ester with branched chain alkyl group 1.0% by mass
Surfactant (phosphate ester-based surfactant) 2.0% by mass
Organic amine (oxyethylene alkylamine) 2.0% by mass
Polyvinyl butyral resin (hydroxyl group amount: 36 mol%, average degree of polymerization: 300) 5.0% by mass
Ketone resin 15.0% by mass
Spinning property imparting agent (polyvinylpyrrolidone resin) 0.5% by mass

Examples 2-18
As shown in Table 1, the ink compositions for oil-based ballpoint pens of Ink Dispensing Examples 2 to 18 were obtained in the same procedure as in Example 1 except that the ink components and chip specifications were changed. The measurement and evaluation results are shown in the table.

Comparative Examples 1 to 3
As shown in the table, the ink compositions for writing tools of Comparative Examples 1 to 3 were obtained in the same procedure as in Example 1 except that the ink components and chip specifications were changed. The measurement and evaluation results are shown in the table.

Test and Evaluation The oil-based ballpoint pen ink composition (0.27 g) prepared in Examples 1 to 18 and Comparative Examples 1 to 3 was placed in an ink storage cylinder (polypropylene), and a ball having a ball diameter of φ1.6 mm was rotatable. An oil-based ballpoint pen is manufactured by filling a refill for an oil-based ballpoint pen equipped with a held ballpoint pen tip (with a coil spring that presses the ball directly into the inner wall of the tip edge of the tip, the amount of movement in the axial direction of the ball is 12 μm). bottom. The following tests and evaluations were carried out using the writing paper JIS P3201 as the writing test paper.
The ink consumption per 100 m of Example 1 was 70 mg / 100 m when a spiral writing test was performed with an oil-based ballpoint pen.

Ink leakage suppression test: The pen tip was left facing downward for 7 days in an environment of 30 ° C. and 85% RH, and ink leakage from the tip tip was confirmed.
Those without ink droplets on the tip tip ・ ・ ・ ◎
Ink droplets on the tip of the chip are within 1/4 of the taper part ... ○
Ink droplets on the tip of the chip are 1/4 or more and 1/2 or less of the taper part ... △
Ink droplets on the tip of the chip are more than 1/2 of the taper part ... ×

Writing taste: A handwritten sensory test was conducted and evaluated.
Very smooth ... ◎
Smooth ... ○
Smoothness at a level that does not cause any problems in practical use ・ ・ ・ △
Heavy things ... ×

Writing performance test: After writing by hand, leave the tip of the tip out in an environment of 20 ° C and 65% RH for 24 hours, then write in the running test under the following writing conditions, and the length of the handwriting blur in writing. Was measured.
<Writing conditions> Under the conditions of a writing load of 200 gf, a writing angle of 70 °, and a writing speed of 4 m / min, linear writing was performed with a running tester and evaluated.
The length of the handwriting blur is less than 8 mm ... ◎◎
Handwriting cassoulet length is less than 15 mm ... ◎
The length of the handwriting blur is 15 mm or more and less than 20 mm ... ○
The length of the handwriting blur is 20 mm or more and less than 40 mm ... △
Handwriting cassoulet length of 40 mm or more ... ×

Crying / body test: Evaluated by handwriting.
Things with no or little crying / bottom ... ◎
There is crying and sickness, but there is no problem in practical use ... ○
Those with severe crying and sickness that pose a problem in practice ... ×

In Examples 1 to 18, good performances were obtained in all of the ink leakage suppression test, writing taste, writing performance, and crying / bottoming test.
Further, when the inks using the pigment as the colorant in Examples 1 to 18 were viewed under a microscope, the pigment dispersibility was good and there were no precipitates.
The ink viscosities of Examples 3, 14 and 16 were measured using a viscometer Viscometer RVDVII + Pro CP-52 spindle manufactured by Brookfield Co., Ltd.
In Example 3, a shear rate of 0.18 sec ^-1 and an ink viscosity of 27560 mPa · s in an environment of 20 ° C., an ink viscosity of 8460 mPa · s and a non-Newtonian viscosity at ^{a shear rate of 3.4 sec -1 in an environment of 20 ° C.} The grant index n was 0.60.
In Example 14, in an environment of 20 ° C., a shear rate of 0.18 sec ^-1 , ink viscosity = 14330 mPa · s, in an environment of 20 ° C., a shear rate of 3.4 sec ^-1 , ink viscosity = 9800 mPa · s, non-Newtonian viscosity. The grant index n was 0.87.
In Example 16, the shear rate was 0.18 sec ^-1 and the ink viscosity was 14100 mPa · s in an environment of 20 ° C.

In Comparative Examples 1 and 2, since the polyglycerin fatty acid ester was not used, the ink leakage suppressing performance and the writing performance were inferior.

In Comparative Example 3, the fatty acid amide wax was added as a shear thinning agent to increase the ink viscosity, but since the polyglycerin fatty acid ester was not used, the ink leakage suppressing performance and the writing performance were inferior.

In addition, when using a spill-type writing instrument (striking-type ballpoint pen) such as a knock-type writing instrument or a rotary feeding-type writing instrument, ink leakage suppression performance is one of the most important performances. For oil-based ballpoint pens containing polyglycerin fatty acid ester as in the present invention, which can suppress ink leakage (ink leakage from the gap between the ball and the tip of the tip) from the gap of the ink leakage suppression performance. It is effective to use an ink composition.

As in the present invention, in order to suppress ink leakage and improve writing performance, a ball rotatably held at the tip of a ballpoint pen tip is pressed against the inner wall of the tip edge of the tip directly by a coil spring or via a pressing body. Therefore, it is preferable to provide a valve mechanism that gives a gap between the inner wall of the tip edge of the chip and the ball by the pressing force at the time of writing to allow ink to flow out, and closes even a minute gap at the tip of the tip when not in use.

Further, in the present embodiment, for convenience, an oil-based ballpoint pen containing a refill for an oil-based ballpoint pen in which the ink composition for a writing tool is directly contained is illustrated. The storage cylinder may be a direct-packed ballpoint pen or a writing tool in which the ink composition for a writing tool is directly stored in the shaft cylinder. Further, in this embodiment, for convenience, a ballpoint pen tip formed by cutting a wire rod is illustrated, but a ballpoint pen tip formed by pressing a pipe material may be used.

Further, in the present embodiment, an oil-based ballpoint pen in which a ballpoint pen refill containing an ink composition for an oil-based ballpoint pen is arranged in a barrel is illustrated, but the oil-based ballpoint pen of the present invention uses ink for the barrel itself. The storage cylinder may be a direct-packed oil-based ballpoint pen in which the ink composition for an oil-based ballpoint pen is directly stored in the shaft cylinder, or the ink composition for an oil-based ballpoint pen is stored in the ink storage cylinder (ballpoint pen refill). ) May be used as it is as a ballpoint pen.

The present invention can be used as a ballpoint pen, and more specifically, can be widely used as a writing instrument such as a cap type and a haunting type.

Claims (6)

An oil-based ballpoint pen having a ballpoint pen tip rotatably holding a ball at the tip of an ink containing cylinder and accommodating an oil-based ballpoint pen ink composition in the ink-containing cylinder. The composition comprises a colorant, an organic solvent, a shear-reducing viscosity-imparting agent, and a polyvinyl butyral resin, the shear-reducing viscosity-imparting agent is a polyglycerin fatty acid ester, and the amount of hydroxyl groups of the polyvinyl butyral resin is 30 to 40 mol. The polyglycerin fatty acid ester is hexaglycerin monostearic acid ester or hexaglycerin tristearic acid ester, and the ink viscosity at 20 ° C. and a shear rate of 3.4 sec ^-1 is 3000 to 30000 mPa · s. An oil-based ballpoint pen characterized in that the Newton viscosity imparting index n = 0.55 to 0.95, and the amount of movement of the ball of the ballpoint pen tip in the vertical axis direction is 30 μm or less. The oil-based ballpoint pen according to claim 1, wherein the ink composition for an oil-based ballpoint pen contains a phosphoric acid ester-based surfactant or a fatty acid. The oil-based ballpoint pen according to claim 1 or 2, wherein the average degree of polymerization of polyglycerin constituting the polyglycerin fatty acid ester is in the range of 1 to 10. The oil-based ballpoint pen according to any one of claims 1 to 3, wherein the content of the shear thinning agent is 0.1 to 10.0% by mass with respect to the total amount of the ink composition. .. The oil-based ballpoint pen according to any one of claims 1 to 4, wherein the HLB value of the polyglycerin fatty acid ester is in the range of 4 to 14. The oil-based ballpoint pen according to any one of claims 1 to 5 , wherein the ink composition for an oil-based ballpoint pen further contains a fatty acid ester (excluding polyglycerin fatty acid ester).