JP6903600B2 - Ink composition for oil-based ballpoint pens and oil-based ballpoint pens using them - 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, unlike other types of writing instruments, a ballpoint pen is a ballpoint pen tip composed of a metal tip made of stainless steel or the like at the tip and a transfer ball made of a metal such as super steel held in the ball receiving seat of the metal tip. However, there is a problem that the ball-point pen is worn due to the rotation of the ball during writing, line skipping and blurring occur in the handwriting, and the writing quality deteriorates.

In order to solve these problems, many ink compositions for oil-based ballpoint pens using various lubricants have been proposed for the purpose of improving the lubricity between the ball and the ball seat of the ballpoint pen tip.

As an ink composition for an oil-based ballpoint pen using such a lubricant, as an ink composition using an alkyl β-D-glucoside, JP-A-5-331403 “Oil-based ballpoint pen ink” has an average molecular weight of 200 to 4000,000. As a material using a certain polyethylene glycol, Japanese Patent Application Laid-Open No. 7-196971 “Ink Composition for Oil-based Ballpoint Pen”, N-acylamino acid, N-acylmethyltauric acid, and N-acylmethylalanine are used. Japanese Unexamined Patent Publication No. 2007-176995, "Ink for oil-based ballpoint pens", and Patent No. 3500552, "Oil-based ink composition for ballpoint pens", which use a phosphate ester, and the like are disclosed.

"Japanese Patent Laid-Open No. 5-331403" "Japanese Patent Laid-Open No. 7-196971" "Japanese Patent Laid-Open No. 2007-176995" "Patent No. 3500552"

However, when various lubricants such as Patent Documents 1 to 4 are used, it is possible to suppress the wear of the ball seat while improving the writing quality to some extent, but the lubricity is not satisfactory and there is room for improvement. was there. Further, recently, when writing on copy paper, writing pressure is higher than usual (high writing pressure writing), so that it is required to further improve lubricity and improve high writing pressure writing performance. .. Further, an ink composition for an oil-based ballpoint pen that improves the writing performance when the tip tip is dried while the tip tip is left in the atmosphere is also desired, and in particular, a knock-type oil-based ballpoint pen or a rotary feeding-type oil-based ink composition is desired. When a haunting type oil-based ballpoint pen such as a ballpoint pen is used, it is important because the writing performance is likely to be affected.

An object of the present invention is to obtain an ink composition for an oil-based ballpoint pen having improved lubricity, suppression of wear of a ball seat, and improved writing quality, and an oil-based ballpoint pen using the same.

The present invention is an ink composition for an oil-based ballpoint pen, which comprises "1. a colorant, an organic solvent, and butoxyethyl acid phosphate," in order to solve the above problems.
2. The ink composition for an oil-based ballpoint pen according to Item 1, wherein the content of the butoxyethyl acid phosphate is 0.1 to 10.0% by mass with respect to the total amount of the ink composition.
3. 3. The ink composition for an oil-based ballpoint pen according to item 1 or 2, wherein the colorant is a pigment.
4. The oil-based ballpoint pen ink composition according to any one of items 1 to 3, wherein the oil-based ballpoint pen ink composition further contains a salt-forming dye.
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 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 contains a fatty acid ester.
7. 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 6 is placed in the ink containing cylinder. An oil-based ballpoint pen that is characterized by being housed. ".

INDUSTRIAL APPLICABILITY The present invention is an ink composition for an oil-based ballpoint pen capable of improving lubricity, suppressing wear of a ballpoint pen, improving writing quality, and particularly improving lubricity under high writing pressure (writing load 300 to 500 gf). And an oil-based ballpoint pen using it could be obtained.

A feature of the present invention is to prepare an ink composition for an oil-based ballpoint pen containing butoxyethyl acid phosphate. By containing butoxyethyl acid phosphate, it is possible to maintain the lubricity between the ball and the chip body, improve the writing quality, and improve the wear suppression of the ball seat. By the lubrication layer made of butoxyethyl acid phosphate, it is possible to maintain lubricity even under high writing pressure (writing load 300 to 500 gf), suppress wear of the ball seat, and improve writing quality.

(Butoxyethyl acid phosphate)
The butoxyethyl acid phosphate used in the present invention is a phosphoric acid ester represented by the following general formula (Chemical Formula 1) and having butoxyethyl (C ₄ H ₉ OCH ₂ CH _{2 O).} Specific examples thereof include a monoester of butoxyethyl acid phosphate (n = 1 of chemical 1) and a diester of butoxyethyl acid phosphate (n = 2 of chemical 1), and a mixture thereof.

In the butoxyethyl acid phosphate, P having a structure of the general formula (Chemical formula 1) is adsorbed on a metal ballpoint pen tip body or a ball, and is formed by a butoxyethyl group (C ₄ H ₉ OCH ₂ CH ₂ O) adjacent to P. By forming the lubricating layer, it is possible to improve the lubricity, suppress the wear of the ball seat, and improve the writing quality. In particular, unlike the conventional phosphoric acid ester, by having a butoxyethyl group (C ₄ H ₉ OCH ₂ CH ₂ O), a lubricating layer having higher lubricity is formed, so that the writing pressure is high (writing load 300). It is possible to maintain lubricity even at ~ 500 gf), suppress wear of the ball seat even under high writing pressure (writing load 300 to 500 gf), and improve writing quality, which is effective.

In the present invention, the above effects can be obtained by using butoxyethyl acid phosphate, but by having a butoxyethyl group (C ₄ H ₉ OCH ₂ CH ₂ O, carbon chain 4 of the terminal alkyl group). It is presumed as follows that a special effect can be obtained.
If the carbon chain of the terminal alkyl group of butoxyethyl acid phosphate is 5 or more and the carbon chain is made too long, the writing feel and writing performance will be good, but the ball seat under high writing pressure (writing load 300 to 500 gf) It is difficult to obtain wear suppression. This is because when the number of carbon chains of the terminal alkyl group is 5 or more, steric damage is likely to occur between the carbon chains of each other, and even if the phosphate groups adsorbed on the metal become dense, the arrangement of the carbon chains is difficult to become dense. This is because a lubricating layer having sufficient lubricity cannot be obtained, and it is difficult to suppress wear of the ball seat under high writing pressure. Furthermore, since the polarity of the terminal alkyl group shifts to the oily side, the affinity for the organic solvent is inferior, which easily affects the dissolution stability, especially the glycol ether solvent, which easily affects the dissolution stability in the ink. Sexual problems are more likely to occur. For this reason, metal salt precipitates are likely to be generated due to the influence of metal ions and the like in the metal chip due to long-term storage, the ink stability with time is likely to be inferior, and it is difficult to obtain the lubrication effect as in the present invention.
On the other hand, when the carbon chain of the terminal alkyl group is 3 or less, the wear suppression of the ball seat under high writing pressure is good, but the alkyl group does not sufficiently extend in the ink, and the ball and the ball seat Since it is a lubricating layer with insufficient cushioning between them, it tends to affect the writing quality and writing performance. Therefore, since the terminal alkyl group has a butyl group (carbon chain 4 of the terminal alkyl group), it is possible to obtain the effect of suppressing wear of the ball seat under high writing pressure and improving writing quality and writing performance.
Further, regarding the butoxyethyl group, as an example, in the polyoxyethylene phosphate-based activator, the alkyl group and the ethylene oxide group are repelled by having a plurality of ethylene oxide groups, and the alkyl group is generated in the ink. Although it is difficult to extend linearly and the writing performance is good, the hydrophobic groups of the phosphoric acid ester adsorbed on the metal are not closely arranged, so that the lubricity, particularly the lubricity under high writing pressure, tends to be inferior.
Therefore, in the present invention, it has a structure having a butoxy group and one ethylene oxide group, such as a butoxyethyl group _{(C 4} H ₉ OCH ₂ CH _{2 O, carbon chain 4 of the terminal alkyl group).} As a feature, by using a structure different from the conventional one, a remarkable lubricating effect can be obtained.

Furthermore, regarding butoxyethyl acid phosphate, the monoester of butoxyethyl acid phosphate (n = of Chemical formula 1) is a monoester of butoxyethyl acid phosphate, considering that the wear of the ball seat is suppressed even under high writing pressure (writing load 300 to 500 gf) and the writing taste is taken into consideration. It is preferable to use a mixture of 1) and a diester of butoxyethyl acid phosphate (n = 2 of Chemical formula 1). Further, in consideration of the above, with respect to the mixing ratio of the monoester of butoxyethyl acid phosphate and the diester of butoxyethyl acid phosphate as a mixture, the larger the number of butoxyethyl groups, the more advantageous the lubricity. Since it has two butoxyethyl groups (C ₄ H ₉ OCH ₂ CH ₂ O), it is preferable that the diester of butoxyethyl acid phosphate is large. Therefore, the range of 1: 1 to 1: 5 is preferable, and if further considered, the range of 1: 1 to 1: 3 is preferable.

The content of the butoxyethyl acid phosphate 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 lubricity, and if it exceeds 10.0% by mass, the aging of the ink tends to be unstable. In consideration of the above, 0.1 to 5.0% by mass is preferable, and more in consideration, 0.3 to 3.0% by mass is preferable.

(Organic amine)
When butoxyethyl acid phosphate is used as in the present invention, it is preferable to use an organic amine. This is because butoxyethyl acid phosphate is an acidic phosphoric acid ester, so by neutralizing it with an organic amine and stabilizing it in the ink, the effect of butoxyethyl acid phosphate can be easily obtained and coloring. This is to make it easier to improve the stability of other ink components such as agents over time. Considering the stability of the organic amine with butoxyethyl acid phosphate and a colorant, it is preferable to use a secondary amine or a tertiary amine. Regarding the reactivity in oil-based inks, the primary amine is the strongest, followed by the secondary amine and the tertiary amine, and the primary amine is the butoxyethyl acid phosphate, colorant and others. It easily reacts with the components of the ink and tends to affect the stability of the ink over time. Therefore, it is preferable to use a secondary amine or a tertiary amine, and more consideration is given, it is preferable to use a tertiary amine.

Regarding organic amines, specifically, amines having ethylene oxide such as oxyethylene alkylamine and polyoxyethylene alkylamine, alkylamines such as laurylamine and stearylamine, distearylamine, dimethyllaurylamine and dimethyl Examples thereof include aliphatic amines such as dimethylalkylamines such as stearylamine and dimethyloctylamine. Among them, amines having ethylene oxide and dimethylalkylamines are preferable in consideration of stability in ink.

Further, the total amine value of the organic amine is preferably 100 to 300 (mgKOH / g) in consideration of stability with butoxyethyl acid phosphate, a colorant and other components. If it exceeds 300 (mgKOH / g), the reactivity is strong and it easily reacts with the above components, so that the stability of the ink with time tends to be inferior. Further, if the total amine value is less than 100 (mgKOH / g), the stability of butoxyethyl acid phosphate in the ink is likely to be affected, and when an oil-based ballpoint pen is used, metals such as balls and chip bodies are used. Adsorption is likely to be inferior and lubrication performance is difficult to obtain. The range of 150 to 300 (mgKOH / g) is preferable in consideration of stability and lubricity with butoxyethyl acid phosphate, and 200 to 300 (mgKOH / g) is preferable in consideration of stability. With the most consideration, 230 to 270 (mgKOH / g) 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 values: 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 based on the total amount of the ink composition in consideration of stability with butoxyethyl acid phosphate, a colorant and other components, which will be described later. Considering the neutralization with respect to the surfactant, 0.5 to 5.0% by mass is preferable.

When the content of the butoxyethyl acid phosphate with respect to the total amount of the ink composition is A and the content of the organic amine with respect to the total amount of the ink composition is B, 0. The relationship of 1 ≦ A / B ≦ 5 is preferable, and more consideration is given, 0.1 ≦ A / B ≦ 3 is preferable, and the relationship of 0.1 ≦ A / B ≦ 2 is more preferable.

(Colorant)
The colorant used in the present invention is not particularly limited to dyes, pigments and the like, and can be appropriately selected and used, and dyes and pigments may be used in combination. 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, basic dyes and organic acids. 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. Specifically, regarding the 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.

Further, as the colorant, it is preferable to use at least a salt-forming dye in consideration of the time-dependent stability due to the compatibility with the acidic substance butoxyethyl acid phosphate, and further, the stable salt-forming bond makes it stable over time. Considering that the property can be maintained, 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 acid dye, and a salt-forming dye of an acid dye and an organic amine. Considering more, it should be used from among azo-based basic dyes, salt-forming dyes having azo-based skeleton dyes using azo-based acidic dyes, triallylmethane-based basic dyes, and salt-forming dyes having aromatic amines. Of these, since the bond is stable and the effect on butoxyethyl acid phosphate is unlikely to appear, a salt-forming dye of an azo-based acidic dye and a basic dye, and a salt-forming dye of an azomethine-based basic dye and an organic acid. , It is preferable to use from among salt-forming dyes of acidic dyes and aromatic amines.
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. , And specific examples thereof include alkylbenzene sulfonic acid, naphthalene sulfonic acid, naphthalene sulfonic acid-formaldehyde condensate, alkyldiphenyl ether disulfonic acid, and polyoxyethylene alkylphenyl ether phosphoric acid. Further, it is preferable to use alkylbenzene sulfonic acid as the organic acid in consideration of long-term stability in the ink even if it is neutralized with a more azo-based basic dye.

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.

As the colorant, it is preferable to use a pigment in consideration of lubricity. This is because the pigment particles are used, and the pigment particles enter the gap between the ball and the chip body to act like a bearing. It is easy to use a pigment because it is easy to suppress metal contact, thereby improving lubricity, improving writing quality, and easily obtaining the effect of suppressing wear of the ball bearing. In particular, due to the synergistic effect of the lubricating layer of butoxyethyl acid phosphate and the action of pigment particles and bearings, it is easy to maintain lubricity even under high writing pressure (writing load 300 to 500 gf), suppressing wear of the ball seat and improving writing quality. It can be improved. Further, the average particle size is preferably 1 to 500 nm in consideration of the gap relationship inside the ballpoint pen tip. It is more preferably 30 to 350 nm, and even more preferably 50 to 300 nm. Here, the average particle size is determined by using a laser diffraction method, specifically, a laser diffraction type particle size distribution measuring machine (trade name "Microtrac HRA9320-X100", Nikkiso Co., Ltd.), and using a standard sample or another measuring method. It can be obtained from the particle size (D50) when the cumulative volume of the particle size distribution measured based on the calibrated value is 50%.
Since the pigment exerts the above-mentioned action and effect in the dispersed state of the pigment in the ink composition for an oil-based ballpoint pen, it is preferable to determine the particle size in the dispersed state. Further, the pigment is preferable because it has excellent water resistance and light resistance and good color development can be obtained.

As the type of pigment, considering the lubricity due to compatibility with butoxyethyl acid phosphate, it is preferable to use it from carbon black, quinacridone-based, slene-based, and diketopyrrolopyrrole-based pigments, and further compatibility with time. Therefore, considering the stability of the ink over time, it is preferable to use a quinacridone-based pigment.

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. Considering this, it is preferably 7.0 to 25.0% by mass, and further considering it, it is 10.0 to 20.0% 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 writing tools, such as alcohol solvents.

Among these organic solvents, considering the solubility with butoxyethyl acid phosphate, the effect of improving the lubricity is also improved by dissolving and stabilizing the ink composition for oil-based ballpoint pens using a water-insoluble organic solvent. It is preferable because it is easy to obtain.
Among them, it is preferable to use a glycol ether solvent. This is because the affinity of butoxyethyl acid phosphate with the butoxyethyl group tends to be good with respect to the glycol ether solvent, and the dissolution is stable, so that the ink aging is likely to be stable even during long-term storage. Furthermore, 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. It is preferable to use an aromatic glycol ether solvent in consideration of its effectiveness and stability in ink. 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 and easily dries at the tip of the tip, and the inside of the writing tip (inside the tip of the tip). This is preferable because it suppresses ink leakage from the gap at the tip of the writing and improves the ink leakage suppression performance by thickening the viscosity faster. Further, aromatic alcohols such as benzyl alcohol also have an effect of improving lubricity, and therefore it is preferable to use at least. Therefore, it is preferable to use a glycol ether solvent and an alcohol solvent in combination.

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. 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, in consideration of the drying property at the tip of the chip. It is 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.

For ketone resin, when used in combination with butoxyethyl acid phosphate, the lubrication action is easy to work synergistically, and under high writing pressure (writing load 300 to 500 gf), lubricity is improved and wear suppression of the ball seat is further improved. It is preferable to do so. Among the ketone resins, a ketone resin having a cyclic structure such as an aromatic ring skeleton (having a benzene ring such as a phenyl group, an acetophenone group, or a naphthalene group) or a cyclohexane skeleton (having a cyclohexane ring such as a cyclohexane group or a cyclohexanone group) can be used. preferable. This is because the cushioning effect of the ketone resin having an annular structure can be obtained, the lubricity is improved under high writing pressure (writing load 300 to 500 gf), and the wear suppression of the ball seat is further improved, and more preferably. Since the ketone resin having an aromatic ring skeleton has many double bond structures, a stronger cushioning effect can be easily obtained, so that the lubricity under high writing pressure (writing load 300 to 500 gf) is effective. preferable.

When polyvinyl butyral resin is also used in combination with butoxyethyl acid phosphate, it is easy to form a lubricating layer that can obtain a higher lubricating effect. Therefore, an elastic ink layer is always formed between the ball and the ball seat to make it difficult to make direct contact with the ball, so that the writing quality can be easily improved. Further, when the polyvinyl butyral resin is used, it is preferable because the film formed makes it easier to improve ink leakage, and when a pigment is used as a colorant, a pigment dispersion effect can be obtained. Therefore, the polyvinyl butyral resin is used. It is preferable to use it.
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 polyvinyl butyral resin preferably has a hydroxyl group content of 25 mol% or more. This is because a polyvinyl butyral resin having 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. 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 quality 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, ballpoint pens are effective with writing instruments 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 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 quality. Further, more considered, the average degree of polymerization is preferably 1500 or less, and more preferably 1000 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. ..

The content of the polyvinyl butyral resin is 70% or more of the total content of the resin in the oil-based ballpoint pen composition, and is preferably used as the main resin. This is because when the content of the polyvinyl butyral resin is less than 70% of the content of the total resin, it is easy for other resins to hinder the formation of an elastic ink layer, which has the effect of improving the writing quality. It becomes difficult to obtain, and it is easy to inhibit the formation of the resin film at the tip of the chip, the ink dripping cannot be suppressed, and the formation of an elastic ink layer is inhibited, so that the effect of improving the writing quality is obtained. This is because it becomes difficult to get rid of. Considering the tendency to improve the writing taste and the ink dripping performance, the content of the polyvinyl butyral resin is preferably 90% or more with respect to the content of the total resin.

If the content of the polyvinyl butyral resin is less than 1.0% by mass with respect to the total amount of the ink composition, the desired lubricity and ink leakage suppression performance are likely to be inferior, and if it exceeds 40.0% by mass, the ink is contained. Since the solubility tends to be inferior, 1.0 to 40.0% by mass is preferable with respect to the total amount of the ink composition. Further, considering it, 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 affects the writing quality, so 5.0 to 30.0% by mass is preferable. preferable.

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 to 34 mol%, average degree of polymerization: 400 to 650), B45H (hydroxyl amount: 26 to 31 mol%, average degree of polymerization: 600 to 850), B60T (hydroxyl amount: 34 to 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.

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.

(Surfactant)
In the present invention, it is preferable to use a surfactant in consideration of the lubricity and the improvement of the writing performance when the tip tip is dried while the tip tip is left in the air. .. This is because when a surfactant is used, the formed film tends to be softened, the writing performance can be improved, and the lubricity can also be improved. Examples of the surfactant include fatty acids, fatty acid esters, silicone-based surfactants, fluorine-based surfactants, and phosphoric acid ester-based surfactants. Among them, in consideration of the above effects, it is preferable to use one or more of fatty acids, silicone-based surfactants, and phosphoric acid ester-based surfactants.
In particular, the butoxyethyl acid phosphate used in the present invention _{is a phosphate ester having butoxyethyl (C 4} H ₉ OCH ₂ CH ₂ O), and the phosphate ester-based surfactant (excluding butoxyethyl acid phosphate) is used. Since having phosphoric acid as the same skeleton makes it compatible and easily obtains a synergistic lubricating effect, it is preferable to use a phosphoric acid ester-based surfactant (excluding butoxyethyl acid phosphate). By using butoxyethyl acid phosphate and a phosphate ester-based surfactant (excluding butoxyethyl acid phosphate) in combination, the lubricating layer of the butoxyethyl acid phosphate and the lubricating layer of the phosphate ester-based surfactant can be combined. By interacting with each other, a lubricating layer having higher lubricity can be formed, so that the lubricity is maintained even under high writing pressure (writing load 300 to 500 gf), and the effect of easily suppressing the wear of the ball seat is achieved. I guess. Further, when the above-mentioned polyvinyl butyral resin is used, it is more preferable because the ink layer formed by the polyvinyl butyral and the lubricating layer can easily improve the lubricity.

The HLB value of the surfactant is preferably 6 to 14, in consideration of further improving both the writing performance and the lubricity. This is because when the HLB value exceeds 14, the hydrophilicity tends to be strong, and the solubility in the oil-based ink tends to be inferior, so that the effect of the surfactant is difficult to obtain and the lubricating effect is difficult to obtain. .. Further, if the HLB value is less than 6, the lipophilicity becomes too strong, the compatibility with the organic solvent is likely to be affected, the ink aging is difficult to stabilize, and the writing performance is difficult to improve. Further, considering the lubricity, the HLB value is preferably 12 or less, the HLB value is preferably 6 to 12, and more considering the writing performance, the HLB value is preferably 7 to 12.
The HLB can be obtained from the Griffin method, the Kawakami method, etc. As an example, as a general formula, HLB = 7 + 11.7 log (Mw / Mo), (Mw; molecular weight of hydrophilic group, Mo; lipophilic group). It can be obtained from the molecular weight) and the like. In particular, in the infestation type writing instruments such as the knock type writing instrument and the rotary feeding type writing instrument, unlike the cap type writing instrument, the pen tip is always exposed to the outside, which affects the writing performance when the writing tip is dried. Since it is easy to use, it is more preferable to use the surfactant having the above HLB value.

Specific examples of the surfactant include oleic acid, stearic acid, and linoleic acid as fatty acids, and silicone-based surfactants include dimethyl silicone, methylphenyl silicone, polyether-modified silicone, and higher grade. Examples thereof include fatty acid ester-modified silicone, and examples of the fluorine-based surfactant include a perfluoro group butyl sulfonate, a perfluoro group-containing carboxylate, a perfluoro group-containing phosphoric acid ester, and a perfluoro group-containing phosphoric acid ester type compound. Examples thereof include products, perfluoroalkyl betaines, and perfluoroalkylamine oxide compounds. Examples of the phosphoric acid ester-based surfactant include a phosphoric acid monoester of a polyoxyethylene alkyl ether or a polyoxyethylene alkyl aryl ether, and a polyoxyethylene alkyl. Examples thereof include phosphoric acid diesters of ethers or polyoxyethylene alkylaryl ethers, phosphoric acid triesters of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers, alkyl phosphoric acid esters, alkyl ether phosphoric acid esters or derivatives thereof. When a phosphate ester-based surfactant (excluding butoxyethyl acid phosphate) is used, the acid value is preferably 160 or less, which improves the lubricity of the phosphate ester-based surfactant. The acid value is preferably 30 to 160 in consideration of stability and lubricity in the ink, and more preferably 70 to 160 in consideration of the acid value. Is expressed by the number of mg of potassium hydroxide required to neutralize the acidic component contained in 1 g of the sample.

The content of the 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.

When the content of the butoxyethyl acid phosphate with respect to the total amount of the ink composition is A and the content of the surfactant with respect to the total amount of the ink composition is B, a balance is achieved in which both the writing performance and the suppression of wear of the ball seat are compatible. Considering this, the relationship of 0.1 ≦ X / Y ≦ 7 is preferable, and more consideration is given, the relationship of 0.1 ≦ X / Y ≦ 5 is preferable.

(Fatty acid ester)
In the present invention, it is preferable to use a fatty acid ester in consideration of the lubricity and the improvement of the writing performance when the tip tip is dried while the tip tip is left in the air. The fatty acid ester facilitates the softening of the film strength formed during ink drying at the tip of the chip, which makes it easier to improve writing performance, and further makes it easier to improve lubricity, resulting in high writing pressure (writing load 300). Since it is easy to maintain lubricity even at ~ 500 gf), it is preferable because it is easy to suppress wear of the ball seat (high writing pressure writing property) and to improve writing quality and writing performance.

The fatty acid ester is an esterification reaction of a fatty acid and an alcohol such as a monohydric alcohol or a polyhydric alcohol. Among the fatty acid esters, a branched chain is considered in consideration of further improving writing performance. It is preferable to use a fatty acid ester having an alkyl group. This is because the fatty acid ester having a branched alkyl group has a bulkier structure than the linear structure, and therefore, due to the bulkiness of the branched alkyl group, it is adsorbed on the metal ball surface or the ball seat of the chip body. This is because it is easy to form a thicker lubricating film and the lubricity is more easily improved. At the same time, the bulkiness of the branched alkyl group softens the film strength formed when the tip of the chip is dried with ink, resulting in writing performance. This is to improve.

Further, the fatty acid ester preferably has an acid value of 0.01 to 5 (mgKOH / g), which has good compatibility with the acidic phosphoric acid ester and other components in the oil-based ink. This is because it is stable in ink for a long period of time, 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 is preferably a polyhydric alcohol. The reason for this is not clear, but the more hydroxyl groups of the alcohol used in the esterification reaction of the fatty acid ester, the easier the moisturizing effect, and the softer the strength of the film formed when the tip of the chip dries. Since the effect of smoothing the rotation of the ball can be obtained, it is presumed that the writing performance is improved without causing brush stroke blurring. Considering that the writing performance is further improved, a polyhydric alcohol having a hydroxyl group of 4 or more valence is preferable, and a hydroxyl group of 5 or more valence is more preferable. 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 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 erithritol, 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 acid used in the esterification reaction of the fatty acid ester include valeric acid, isovaleric acid, caproic acid, 2-ethylbutanoic acid, heptanic acid, 2-methylcaproic acid, and 3 as monocarboxylic acids. -Methylcaproic acid, 2-ethylpentanoic acid, 3-ethylpentanoic acid, isoheptanoic acid, caproic acid, 2-ethylcaproic acid, nonanoic acid, 3,5,5-trimethylcaproic acid, neononanoic acid, capric acid, neodecanoic acid , Lauric acid, valeric 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 lubricity, and if it exceeds 10.0% by mass, the ink aging tends to be unstable. Considering the tendency, 0.1 to 5.0% by mass is preferable, and more considering it, 0.1 to 3.0% by mass is preferable, and 0.3 to 2.0% by mass is most preferable.

The blending ratio of the acidic phosphoric acid ester to the fatty acid ester (acidic phosphoric acid ester / fatty acid ester) is preferably 0.01 to 5 times on a mass basis. This is because it is easy to achieve both the suppression of wear of the ball seat and the writing performance in the above range. Considering more, it is preferable that the compounding ratio is 0.05 to 3 times based on the mass. In consideration of the above, it is preferable that the compounding ratio is 0.1 to 2 times based on the mass.

In addition, as a viscosity modifier, a resin such as terpene resin, alkyd resin, phenoxy resin, polyvinyl acetate, a pseudoplasticizing agent such as fatty acid amide, hydrogenated castor oil, a colorant stabilizer, and a plasticizer are used. , Chelating agent, water and the like may be used as appropriate. These may be used alone or in combination of two or more.

The ink viscosity of the ink composition for an oil-based ball pen of the present invention is not particularly limited, but ^{when the ink viscosity at 20 ° C. and a shear rate of 5 sec -1} (at rest) exceeds 30,000 mPa · s, writing performance and writing are performed. Since the taste tends to be inferior, the ink viscosity at 20 ° C. and a shear rate of 5 sec ^-1 (at rest) is preferably 30,000 mPa · s or less. Further, if the ink viscosity at 20 ° C. and a shear rate of 5 sec ^-1 (at rest) is less than 3000 mPa · s, it is difficult to suppress ink leakage. Therefore, considering ink leakage, it is preferably 3000 mPa · s or more. The ink viscosity is more preferably 5,000 to 25,000 mPa · s, and further, 5,000 to 20,000 mPa · s, in consideration of further improving ink leakage suppression, writing taste, ink tracking performance, and writing performance. preferable.

In order to maintain ink time stability and lubricity such as suppression of metal salt precipitates in the ink composition for oil-based ballpoint pens of the present invention, the pH value is preferably 3.0 to 10.0. This is because if the pH value is less than 3.0, metal ions in the chip body are likely to elute, so metal salt precipitates are likely to occur. If the pH value exceeds 10.0, the colorant in the ink or This is because the ionic bonds of the surfactant are easily separated, which tends to affect the ink stability over time, lubricity, and color tone, and further, pigment dispersion stability cannot be obtained. Further, considering the stability of the ink with time, the pH value is preferably 3.0 to 9.0, and more considering it, the pH value is preferably 3.5 to 8.0.

In the method for measuring the ink composition for an oil-based ballpoint pen, the pH value in the present invention is determined by collecting the oil-based ink in a container, adding ion-exchanged water, heating while stirring, heating and then allowing to cool. After replenishing the amount of evaporated water, it is filtered using a filter paper. Using the upper layer of the filtered filtrate, the pH measurement shows the value measured at 20 ° C. using an IM-40S type pH meter manufactured by DKK-TOA CORPORATION.

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 mean 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. When 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, when butoxyethyl acid phosphate or polyvinyl butyral resin is used, it is more preferable because ink is easily placed on the ball surface, and more preferably 2 to. It is 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. Further, if the diameter of the ball is a relatively small ball diameter of 0.7 mm or less, the smaller the diameter of the ball, the higher the number of rotations of the ball when writing at the same distance. Since the wear of the ball tends to be severe, it is effective to use the acidic phosphate ester used in the present invention, and further, when the ball diameter is 0.5 mm or less, the writing pressure is high (writing load 300 to 500 gf). , It is more effective because the ball seat is easily worn.

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. Considering the property, it is preferable to use a stainless steel chip body.

Further, it is preferable that the amount of movement of the ball of the ballpoint pen tip used in the present invention in the vertical axis direction is 3 to 20 μm. This is because if it is less than 3 μm, it becomes difficult to obtain dark handwriting and good writing quality, and if it exceeds 20 μm, the ink dripping performance is likely to be affected. Considering this, 3 to 12 μm Is preferable.

Next, the present invention will be described with reference to examples.
In the ink composition for an oil-based ballpoint pen of Example 1, a pigment and a pigment dispersant were added to an organic solvent and dispersed by a disperser, and then a pigment dispersion, a dye, an organic solvent, a ketone resin, butoxyethyl acid phosphate, and a thread were drawn. Polypolypyrrolidone was used as the sex-imparting resin, weighed a predetermined amount, heated to 60 ° C., and then completely dissolved using a disper stirrer to obtain an ink composition for an oil-based ballpoint pen. The specific blending amount is as follows.
The ink viscosity of Example 1 was measured at a ^{shear rate of 5 sec -1} (rotation speed 2.5 rpm) in an environment of 20 ° C. using a viscometer Viscometer RVDVII + Pro CP-52 spindle manufactured by Brookfield Co., Ltd. The ink viscosity was 10000 mPa · s.

Example 1
Colorant (salt-forming dye of azo acid dye and basic dye) 10.0% by mass
Colorant (salt-forming dye of azomethine-based basic dye and organic acid) 5.0% by mass
Pigment dispersion (pigment content 12%, quinacridone pigment) 10.0% by mass
Butoxyethyl acid phosphate (mixture of (n = 1 of chemical 1) and (n = 2 of chemical 1)) 1.0% by mass
Alcohol solvent (benzyl alcohol) 9.5% by mass
Glycol ether solvent (ethylene glycol monophenyl ether) 40.0% by mass
Surfactant 2.0% by mass
Organic amine (secondary amine) 2.0% by mass
Ketone resin (ketone resin with aromatic ring) 20.0% by mass
Spinning property imparting resin (polyvinylpyrrolidone resin) 0.5% by mass

Examples 2-25
As shown in the table, inks were blended in the same procedure as in Example 1 except that the components and chip specifications were changed to obtain ink compositions for oil-based ballpoint pens of Examples 2 to 25. The measurement and evaluation results are shown in the table.

Comparative Examples 1 to 4
As shown in the table, the ink compositions for oil-based ballpoint pens of Comparative Examples 1 to 4 were obtained in the same procedure as in Example 1 except that the components and chip specifications were changed. The measurement and evaluation results are shown in the table.

Tests and Evaluations Ballpoint pens in which the ink compositions for oil-based ballpoint pens prepared in Examples 1 to 25 and Comparative Examples 1 to 4 are rotatably held at the tip of an ink containing cylinder (made of polypropylene) with a ball (φ0.5 mm). Along with mounting a chip (movement amount in the vertical axis direction of the ball: 6 μm), the oil-based ballpoint pen ink (0.2 g) of Example 1 is directly stored in the ink storage cylinder, and the ballpoint pen refill is used by Pilot Co., Ltd. An oil-based ballpoint pen manufactured by Corporation (trade name: Super Grip (registered trademark)) was placed to prepare an oil-based ballpoint pen, and the following tests and evaluations were performed using the writing paper JIS P3201 as the writing test paper.

High writing pressure wear resistance test (ball seat wear test): The wear of the ball seat after the writing test was measured with a running tester having a load of 300 gf and a writing angle of 70 ° and 4 m / min.
Ball seat wear less than 5 μm ・ ・ ・ ◎
Ball seat wear of 5 μm or more and less than 10 μm ・ ・ ・ ○
The wear of the ball seat is 10 μm or more and less than 20 μm, but it is writable ... △
The ball seat wears so badly that it causes poor writing ... ×

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 in an environment of 20 ° C and 65% RH for 30 minutes, 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 70 gf, a writing angle of 70 °, and a writing speed of 4 m / min, straight-line writing was performed with a running tester and evaluated.
Handwriting cassoulet length is less than 10 mm ... ◎
The length of the handwriting blur is 10 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 ... ×

In Examples 1 to 25, good performance was obtained in all of the high writing pressure wear resistance test (ball seat wear test), writing quality, and writing performance test.
Examples 20 to 25 contain fatty acid esters in Examples 1, 3, 5, 10, 13, and 19, but when the writing performance is compared, Examples 20 to 25 give better results. Among them, in particular, Examples 20, 21, 23, and 25 (using fatty acids and fatty acid esters esterified with dipentaerythritol) had good writing performance.

In Comparative Examples 1 to 4, since butoxyethyl acid phosphate was not used, in the high writing pressure wear resistance test (ball seat wear test), the ball seat was severely worn and the handwriting was blurred, resulting in poor writing. there were. Further, in Comparative Examples 1 and 2, the writing quality and writing performance were also inferior.

Further, when a haunting type oil-based ballpoint pen such as a knock-type oil-based ballpoint pen or a rotary feeding-type oil-based ballpoint pen is used, writing performance is one of the important performances. Therefore, at least butoxyethyl acid phosphate and phosphoric acid as in the present invention are used. It is effective to use in combination with an ester-based surfactant.

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 an ink composition for an oil-based ballpoint pen, and more specifically, it can be widely used as a cap-type, knock-type or the like oil-based ballpoint pen filled with the ink composition for an oil-based ballpoint pen.

Claims (7)

An ink composition for an oil-based ballpoint pen, which comprises a colorant, an organic solvent, and butoxyethyl acid phosphate. The ink composition for an oil-based ballpoint pen according to claim 1, wherein the content of the butoxyethyl acid phosphate is 0.1 to 10.0% by mass with respect to the total amount of the ink composition. The ink composition for an oil-based ballpoint pen according to claim 1 or 2, wherein the colorant is a pigment. The ink composition for an oil-based ballpoint pen according to any one of claims 1 to 3, wherein the colorant is a salt-forming dye. The ink composition for an oil-based ballpoint pen according to any one of claims 1 to 4, wherein the ink composition for an oil-based ballpoint pen contains a polyvinyl butyral resin or a ketone resin. The ink composition for an oil-based ballpoint pen according to any one of claims 1 to 5, wherein the ink composition for an oil-based ballpoint pen contains a fatty acid ester. A ballpoint pen tip that rotatably holds a ball is provided at the tip of an ink containing cylinder, and the ink composition for an oil-based ballpoint pen according to any one of claims 1 to 6 is contained in the ink containing cylinder. An oil-based ballpoint pen that is characterized by being made of ink.