JP2017171733A - Oily ink composition for writing instruments, and oily ballpoint refill and oily ballpoint pen prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oily ink composition for writing instruments that can maintain the temporal stability of ink in the oily ink composition for the long term, and an oily ballpoint pen refill and an oily ballpoint pen prepared therewith.SOLUTION: An oily ink composition for writing instruments comprises a salt-forming dye of a basic dye and a resin acid, an organic solvent, and an organic amine.SELECTED DRAWING: None

Description

  The present invention relates to an oil-based ink composition for a writing instrument, an oil-based ballpoint pen refill using the same, and an oil-based ballpoint pen.

  Many oil-based ink compositions for writing instruments have been proposed using various dyes such as nigrosine dyes, basic dyes, acid dyes, and types of processed dyes as colorants in oil-based ink compositions for writing instruments. Has been.

  As such an oil-based ink composition for a writing instrument, various colorants are used, and those using a nigrosine dye include those disclosed in JP-A-5-320558, "Oil Black Ink", triarylmethane base. Japanese Patent Application Laid-Open No. 9-165542 “Oil Black Ink”, Japanese Patent Application Laid-Open No. 9-71745 “Oil Black Ink”, and basic dyes are used as the basic dyes. Japanese Patent Application Laid-Open No. 8-134393, “Black Ink Composition for Oil-Based Ballpoint Pens”, etc.

"JP-A-5-320558" "JP-A-9-165542" "Japanese Patent Laid-Open No. 9-71745" "JP-A-8-134393"

  However, in Patent Document 1, when a nigrosine dye is used as a colorant, the concentration is high, the cost is low, and it is conventionally used, but it is stable with ink components such as organic solvents, resins, and surfactants. It was necessary to take ink stability over time into consideration.

  In Patent Documents 2 and 3, when a salt-forming dye of a triarylmethane basic dye and an azo yellow acidic dye is used as a colorant, a part of the salt-forming dye collapses and precipitates over a long period of time. There were also points that should be improved due to the generation of things, poor writing, and cost.

  Further, in Patent Document 4, a salt-forming dye based on a basic dye as a colorant has good ink aging stability, but costs are increased and a new interface is added to improve the writing quality. The writing quality can be improved by including an activator and the like, but the surfactant and the dye may react with each other to generate precipitates.

    Furthermore, even in an ink using a dye as a colorant as described in Patent Documents 1 to 4, improvement in light resistance is required and further demanded.

  An object of the present invention is to provide an oil-based ink composition for writing instruments having good ink aging stability, an oil-based ballpoint pen refill and an oil-based ballpoint pen using the same.

In order to solve the above problems, the present invention
“1. An oil-based ink composition for a writing instrument comprising a salt-forming dye of a basic dye and a resin acid, an organic solvent, and an organic amine.
2. 2. The oil-based ink composition for writing instruments according to item 1, wherein the basic dye is a triarylmethane skeleton basic dye or a xanthene skeleton basic dye.
3. Item 3. The oil-based ink composition for writing instruments according to Item 1 or 2, wherein the organic amine is a secondary amine or a tertiary amine.
4). The oil-based ink composition for writing instruments according to any one of items 1 to 3, further comprising a pigment in the oil-based ink composition for writing instruments.
5. The oil-based ink composition for writing instruments comprises a polyvinyl butyral resin, and the content of the polyvinyl butyral resin is 50% or more based on the total resin content in the oil-based ink composition for writing instruments. Item 5. The oil-based ink composition for a writing instrument according to any one of Items 1 to 4, which is characterized.
6. The oil-based ink composition for a writing instrument according to any one of items 1 to 5, wherein an ink viscosity at 20 ° C. and a shear rate of 5 sec ⁻¹ is 10 to 30000 mPa · s.
7). An oil-based ballpoint pen refill in which the oil-based ink composition for a writing instrument according to any one of Items 1 to 6 is stored in an ink storage cylinder.
8). An oil-in type oil-based ballpoint pen, wherein the oil-based ballpoint pen refill according to item 7 is disposed in a shaft tube so that the oil-based ballpoint pen refill can protrude from the tip of the shaft tube. "

  The present invention was able to obtain an oil-based ink composition for writing instruments, an oil-based ballpoint refill and an oil-based ballpoint pen that can maintain ink aging stability for a long period of time in the oil-based ink composition.

  A feature of the present invention is that the oil-based ink composition for writing instruments comprises a salt-forming dye of a basic dye and a resin acid, an organic solvent, and an organic amine.

  For the colorant used in the present invention, a salt-forming dye of a basic dye and a resin acid is used. This is because a salt-forming dye obtained by salting a basic dye with a resin acid is stable for a long time and is separated in an oil-based ink composition containing components such as an organic solvent, an organic amine, and a surfactant. It is because it is stable without reacting.

  Furthermore, in order to stably dissolve a salt-forming dye of a basic dye and a resin acid in an oil-based ink composition with an organic solvent, it is necessary to contain an organic amine. This is because the salt-forming dye of the basic dye and the resin acid can be kept stable. Furthermore, in the oil-based ink composition for writing instruments, a trace amount of water is contained with respect to the total mass of the ink, such as moisture absorption at the time of manufacture and over time. Although the amount of water in the oil-based ink composition for writing instruments is small, the basic dye has a cationic property, so the basic dye and the resin acid are easily separated, and easily react with other components in the ink. In order to stabilize a salt-forming dye of a basic dye and a resin acid for a long period of time, it is necessary to use an organic amine in combination.

(Salt-forming dyes with basic dyes and resin acids)
In the present invention, it is preferable to use a resin acid in consideration of the basic dye and salt formation stability. This is because salting reaction between resin acid and basic dye makes it easy to form a salt-forming dye with strong ionic bond between resin acid and basic dye, and the ink aging stability is maintained for a long time in oil-based ink. This is because it is easy. Examples of the resin acid include natural rosin such as gum rosin, tall oil rosin and wood rosin, disproportionated rosin, hydrogenated rosin, dehydrogenated rosin, polymerized rosin, modified rosin such as carboxylic acid modified rosin, and alkylphenol resin. . Examples of the carboxylic acid used for the preparation of the carboxylic acid-modified rosin include maleic acid, maleic anhydride, fumaric acid, itaconic acid, itaconic anhydride, citraconic acid, acrylic acid, and methacrylic acid. Among these resin acids, it is preferable to use a modified rosin in consideration of basic dyes and salt formation stability.

  Examples of basic dyes include triarylmethane skeleton, xanthene skeleton, azomethine skeleton, azo skeleton, anthraquinone skeleton, and oxazine skeleton, among which triarylmethane skeleton basic dye, xanthene skeleton base It is preferable to use a functional dye. This is because, by reacting a triarylmethane skeleton basic dye and a xanthene skeleton basic dye to form a salt-forming dye having a strong ionic bond between the resin acid and the basic dye, a variety of oil-based inks are used. This is because the triarylmethane skeleton basic dye is a basic dye having an aromatic ring such as three phenyl groups and naphthyl groups on the same carbon, and it is easy to maintain stability with time in the environment or for a long time. It is most preferable because it has an aromatic ring so that it can be easily balanced and salt formation stability with a resin acid can be easily obtained.

Here, the basic dye that can be used in the present invention includes C.I. I. Basic Blue 1, 7, 19, 26, C.I. I. Basic violet 1, 3, 4, 10, 15, C.I. I. Basic green 1, 4, 7, solvent blue 5, solvent violet 8, and the like. I. Basic Red 1, 1: 1, C.I. I. Basic violet 10, 11 and solvent red 49, and the like. Examples of the azomethine skeleton basic dye include C.I. I. Basic yellow 11, 13, 14, 21, 23, 24, 28, 40, 44, 49, 51, 52, 53, etc. are mentioned. Among these basic dyes, having a diethylamino group (—NH (C ₂ H ₅ ) ₂ —) is preferable because it has high stability when a salt-forming dye with a resin acid is formed. In consideration of the stability of C.I. I. Basic Blue 7 and Solvent Red 49 are preferably used. I. Basic blue 7 is more preferable.

  Further, when the content of the salt-forming dye of the basic dye and the resin acid is less than 0.1% by mass with respect to the total amount of the ink composition, it is difficult to obtain a desired handwriting density, and 40.0% by mass. If it exceeds 50%, the ink aging tends to become unstable, so 0.1 to 40.0% by mass is preferable with respect to the total amount of the ink composition. More preferably, it is 1.0 to 25.0% by mass relative to the total amount of the ink composition, more preferably 5.0 to 20.0% by mass, and considering the stability with the organic amine, 7.0-15.0 mass% is preferable.

(Organic amine)
About the organic amine used in the present invention, amines having ethylene oxide such as oxyethylene alkylamine and polyoxyethylene alkylamine, alkylamines such as laurylamine and stearylamine, distearylamine, dimethyllaurylamine, dimethylstearylamine, Examples thereof include aliphatic amines such as dimethylalkylamine such as dimethyloctylamine. Among them, amines having ethylene oxide and dimethylalkylamines are preferable in consideration of stability in ink, and dimethylalkylamines are preferable in consideration. Is preferred.

  Among the organic amines, it is preferable to use a secondary amine or a tertiary amine in consideration of the stability of the organic amine and the salt-forming dye of the basic dye and the resin acid. This is because the primary amine has the strongest reactivity in the oil-based ink, and then the reactivity with the secondary amine and the tertiary amine becomes small, and the primary amine reacts with the salt-forming dye and other components. In particular, it easily reacts with the salt-forming dye to give a dull color and it is difficult to obtain a dark handwriting. Therefore, considering the stability with the salt-forming dye, it is preferable to use a secondary amine or a tertiary amine, and considering more, it is preferable to use a tertiary amine.

Further, the total amine value of the organic amine is preferably 100 to 300 (mgKOH / g) in consideration of the stability with the salt-forming dye and other components. If this exceeds 300 (mgKOH / g), since the reactivity is strong, it is likely to react with the salt-forming dye and other components, so the ink aging stability tends to be poor. Further, if the total amine value is less than 100 (mgKOH / g), the stability of the salt-forming dye in the ink is likely to be affected, and further neutralization with respect to the phosphate ester surfactant described later is performed. When the oil-based ballpoint pen is used, the adsorptivity of metals such as balls and chip bodies tends to be poor, and it is difficult to obtain lubrication performance. If considering the stability and lubricity with the salt-forming dye more, the range of 150 to 300 (mgKOH / g) is preferable, and considering the stability with the salt-forming dye, 200 to 300 (mgKOH / g). g) is preferable, and 230-270 (mgKOH / g) is preferable in consideration of the most.
The total amine value represents the total amount of primary, secondary, and tertiary amines, and is expressed in mg of potassium hydroxide equivalent to hydrochloric acid required to neutralize 1 g of the sample.

  As for the organic amine, specifically, as oxyethylene alkylamine and polyoxyethylene alkylamine, specifically, Nimine L-201 (total amine number: 232 to 246, secondary amine), 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 amine), DT-208 (total amine number: 146 to 180, tertiary amine) (manufactured by NOF Corporation) and the like. Specific examples of the alkylamine include Farmin 80 (total amine number: 204-210, primary amine), Farmin D86 (total amine number: 110-119, secondary amine), Farmin DM2098 (total amine number: 254). -265, tertiary amine), Farmin DM 8680 (total amine number: 186-197, tertiary amine) (Kao Corporation), Nissan tertiary amine BB (total amine number: 243-263, tertiary amine), the same Examples include FB (total amine value: 230 to 250, tertiary amine) (manufactured by NOF Corporation). You may use these individually 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 to be described later Considering neutralization with respect to the ester surfactant, 0.2 to 5.0% by mass is preferable.

(Organic solvent)
The organic solvent that can be used in the present invention is not particularly limited, and a solvent that is generally used in an ink composition for writing instruments can be used. Among organic solvents, alcohol-based organic solvents are preferable. Examples of the alcohol organic solvent include diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, ethylene glycol, benzyl alcohol, phenylethyl alcohol, methylphenyl carbinol, phthalyl alcohol, methanol, ethanol, Other alcohol solvents such as 1-propanol, 2-propanol, isopropanol, isobutanol, t-butanol, propargyl alcohol, allyl alcohol, 3-methyl-1-butyn-3-ol, ethylene glycol monomethyl ether acetate, etc. Is mentioned. The alcohol-based organic solvent is preferable because the salt-forming dye of the basic dye and the resin acid can be kept stable in the oil-based ink composition. Furthermore, it is preferable because it is easy to volatilize, is easy to dry at the tip of the chip, is easy to form a film, and is easy to improve the ink dripping performance. In the present invention, the alcohol-based organic solvent means one having no ether bond.

  Among the alcohol solvents, aromatic alcohol solvents are preferable because the salt-forming dyes of the basic dye and the resin acid, the solubility of organic amines are improved, and the salt-forming dyes are separated from each other. This is preferable because the stability of ink over time can be further improved.

  Examples of organic solvents other than alcohol organic solvents include glycol ether solvents. Glycol ether solvent is easy to put ink on the ball, works favorably in handwriting scraping and hollowing out, improves writing performance, and when oil ballpoint pen is used, if considering ball seat wear suppression, It is preferable to use a glycol ether solvent. Furthermore, even when the tip end is left in the atmosphere, a uniform thick resin film is formed at the tip end, and the gap between the ball and the tip end is covered to further suppress ink dripping. An aromatic glycol ether solvent is preferable because it can be used.

  Examples of glycol ether solvents include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol monophenyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol dimethyl ether, 3- Examples include methoxybutanol or 3-methoxy-3-methylbutanol.

  These organic solvents can be used alone or in combination of two or more. For example, it is preferable to use a glycol ether solvent and an alcohol solvent in combination. Moreover, it is preferable that either the glycol ether solvent or the alcohol solvent has an aromatic group. In particular, it is preferable to use a glycol ether solvent having an aromatic group and an alcohol solvent having an aromatic group in combination because lubricity can be improved.

  In addition, the content of the organic solvent is likely to affect the writing performance at the time of dry-up even if there is too much alcohol-based organic solvent, while too much glycol ether-based organic solvent absorbs moisture too much, The resin film becomes soft and tends to affect the ink drooping performance and the ink aging stability of the salt-forming dye. Therefore, considering the balance between the writing performance during dry-up and the ink aging stability of the salt-forming dye, the content of the alcohol solvent based on the total mass of the ink composition is A, and the glycol ether solvent ink composition. When the content with respect to the total mass is B, it is preferable to satisfy 0.1 ≦ A / B ≦ 10, more preferably 0.5 ≦ A / B ≦ 7. It is preferable to satisfy ≦ A / B ≦ 5.

  In addition, the content of the organic solvent can improve solubility and handwriting drying property, and can prevent bleeding, etc., so that it is 10.0 to 70.0% by mass relative to the total mass of the ink composition. It is preferable that Moreover, when a glycol ether organic solvent is used as the organic solvent, the content of the glycol ether organic solvent is 10.0 to the total mass of the organic solvent in consideration of the stability with the salt-forming dye. 50.0% by mass is preferable, and 10.0 to 30.0% by mass is more preferable. In addition, when an alcohol solvent is used as the organic solvent, the alcohol solvent content of the organic solvent is improved in order to improve the stability with the salt-forming dye and the drying property at the tip of the chip. It is preferable that it is 30.0-90.0 mass% with respect to the total mass, and it is more preferable that it is 50.0-90.0 mass%.

(Colorant)
As the colorant other than the salt-forming dye, a general dye or pigment may be used. However, in the present invention, when an oil-based ballpoint pen is used, it is preferable to include a pigment. This is because it contains pigment, and pigment particles enter the gap between the ball and the chip body, which acts like a bearing and suppresses metal contact, thereby improving lubricity. Because there is. Therefore, unlike the prior art, the pigment can have the effects of a colorant and a lubricant. Furthermore, the combined use of pigments is preferable because dark handwriting that is difficult to obtain with the salt-forming dye alone can be obtained, and at the same time, light resistance can be improved.

  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 DPP Quinophthalone, selenium, triphenylmethane, perinone, perylene, goxazine, metallic pigment, pearl pigment, fluorescent pigment, phosphorescent pigment and the like. These pigments tend to suppress metal contact and improve lubricity by entering the gaps in the chip body. In particular, in consideration of the gap relationship inside the chip, the average particle size is preferably 300 nm or less, more preferably 200 nm or less. These pigments may be used alone or in combination of two or more. Further, the average particle diameter of the pigment is obtained by a volume standard method by a laser diffraction method (manufactured by MICROTRAC 9320-X100 Honeywell), and is determined by a particle size (D50) at a volume cumulative 50% of the particle size distribution measured by the laser diffraction method. Can be measured.

  Further, the content of the pigment is preferably 0.1 to 20% by mass with respect to the total amount of the ink composition in consideration of the effect as a colorant, but not only the effect as a colorant as in the present invention. In order to improve lubricity, 0.1 to 8.0% by mass is preferable with respect to the total amount of the ink composition. If the amount is less than 0.1% by mass, the lubricity is not sufficient, and it tends to be difficult to improve the writing taste and the suppression of wear of the ball seat. This is because it is too much and the lubricity is easily affected. Further, when a pigment is used, there is an effect of particularly improving the suppression of wear of the ball seat and facilitating the improvement of light resistance, and considering this, it is 0.3 to 5.5 with respect to the total amount of the ink composition. 0 mass% is preferable, and if considering more, 0.5 to 4.0 mass% is preferable with respect to the total amount of the ink composition.

   In addition, as a colorant other than the salt-forming dye, it is preferable to use a metal-containing dye containing Cu, Cr, Fe, Co, and Si in order to improve light resistance. In particular, it is preferable to use a salt-forming dye of an acid metal-containing dye and an amine having an aromatic ring, but this is because of the strong ionic bonding force between the acid metal-containing dye and the amine having an aromatic ring, This is because the ink aging stability can be maintained for a long time in the ink. Furthermore, considering that the stability over time is good, it is preferable to use an acidic metal-containing dye containing Cu. There are phthalocyanine-based and azo-based ones, among which it is preferable to use a copper phthalocyanine-based acid dye. Specifically, examples of the copper phthalocyanine-based acid dye include direct blue 86, direct blue 87, direct blue 199, and the like. In consideration of stability with an amine having an aromatic ring and light resistance, direct blue 86 is preferable.

  The amine having an aromatic ring is an amine having an aromatic ring such as a benzene ring, a naphthalene ring, an anthracene ring, etc., and having an aromatic ring makes it easy to improve the writing taste when an oil-based ballpoint pen is used. Become. This is presumed that the aromatic ring has an effect of suppressing metal contact between the ball and the chip body by forming a lubricating film that is easily adsorbed to the metal chip, improving lubricity and improving writing quality. To do. Therefore, in the present invention, by using a salt-forming dye of an acid metal-containing dye and an amine having an aromatic ring, it becomes possible to improve ink aging stability and writing quality and to easily improve light resistance. Therefore, it is preferable.

  Examples of amines having an aromatic ring include primary amines, secondary amines, tertiary amines and quaternary amines. However, the acid-containing dyes are sufficiently neutralized to produce more stable salt-forming dyes. In order to make it, it is preferable to use a quaternary amine having an aromatic ring.

  As other colorants, oil-soluble dyes, acid dyes, basic dyes, and various salt-forming dyes thereof may be employed as the dye. In addition, the dyes are specifically Bali First Black 1802, Bali First Black 1805, Bali First Black 1807, Bali First Violet 1701, Bali First Blue 1601, Bali First Blue 1605, Bali First Blue 1621, Bali First Red 1320, Bali First Red 1355, Bali First Red 1360, Bali First Yellow 1101, Bali First Yellow 1151, Nigrosine Base EXBP, Nigrosine Base EX, BASE OF BASIC DYES ROB-B, BASE OF BASIC DYES RO6G-B, BASE OF BASIC DYES VPB- B, BASE OF BASIC DYES VB-B, BASEOF BASI C DYES MVB-3 (above, manufactured by Orient Chemical Co., Ltd.), Eisenspiron Black GMH-Special, Eisenspiron Violet C-RH, Eisenspiron Blue GNH, Eisenspirone Blue 2BNH, Eisenspiron Blue C-RH, Eisenspiron Red C-GH, Eisenspiron Red C-BH, Eisenspiron Yellow C-GNH, Eisenspiron Yellow C-2GH, S. P. T.A. Blue 111, S.I. P. T.A. Blue GLSH-Special, S. P. T.A. Red 533, S.D. P. T.A. Orange 6, S. B. N. Violet 510, S.I. B. N. Yellow 530, S.I. R. C-BH (above, manufactured by Hodogaya Chemical Co., Ltd.) and the like.

  Among other colorants, it is preferable to use an organic acid as the acidic substance such as the resin acid, considering the temporal stability due to the compatibility of the basic dye and the salt-forming dye of the resin acid. Specifically, it preferably contains a salt-forming dye of a basic dye and an organic acid. Further, in consideration, it is preferable to include a salt-forming dye of a basic dye and an alkylbenzene sulfonic acid, which is a salt-forming dye having a strong ionic bond between the alkylbenzene sulfonic acid and the basic dye. In oil-based inks, the ink aging stability can be maintained under various environments and for a long period of time. When oil-based ballpoint pens are used, if they have alkylbenzene sulfonic acid, a phenyl sulfone group can be easily adsorbed on metal. This is because it has an effect of suppressing metal contact between the ball and the chip body, and improves lubricity.

  The content of other colorants is preferably 1.0 to 30.0 mass% with respect to the total amount of the ink composition. This is because if the amount is less than 1.0% by mass, a dark handwriting tends to be difficult to obtain, and if it exceeds 30.0% by mass, the ink tends to aggregate in the ink. 3.0-15.0 mass% is most preferable.

(resin)
Further, in the present invention, it is preferable to contain a resin. Examples of the resin used in the oil-based ink composition for writing instruments include polyvinyl butyral resin, polyacetal resin, polyvinyl alcohol resin, cellulose resin, polyvinyl pyrrolidone resin, ketone resin, and terpene. Resin, alkyd resin, phenoxy resin, polyvinyl acetate resin, and the like. In the present invention, when an oil-based ballpoint pen is used, ink dripping performance and writing quality are excellent, and salt formation between the basic dye and resin acid is performed. In order to have excellent ink aging stability with a dye, it is preferable to use a polyvinyl butyral resin. This is because polyvinyl butyral resin forms a resin film at the tip of the tip and covers the gap between the tip of the ball and the tip, thereby suppressing ink drooping. In addition, the ink is always elastic between the ball and the ball seat. This is because the layer is formed so that it is difficult to make direct contact, so that the writing quality can be easily improved.

  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. Although there is a technique suitably used as the dispersant, the present invention relates to improving ink dripping performance and writing quality.

  The polyvinyl butyral resin content is preferably 50% or more based on the total resin content in the ink composition, and is preferably used as the main resin. This is because when the polyvinyl butyral resin content is less than 50% of the total resin content in the ink composition, the other resin inhibits the formation of the resin film on the tip of the chip and suppresses ink drooping. This is because the ink layer cannot be formed, and the formation of an elastic ink layer is hindered, and it becomes difficult to obtain the effect of improving the writing quality. Considering the tendency to improve the ink drooping performance and writing quality, the content of the polyvinyl butyral resin is preferably 70% or more with respect to the total resin content in the ink composition. 90% or more is preferable. Furthermore, the compatibility of the salt-forming dye of the basic dye and the resin acid and the polyvinyl butyral resin is good, and the content of the polyvinyl butyral resin is large, and even if it is 90% or more, the ink aging stability is not easily affected, which is preferable. .

Moreover, it is preferable that polyvinyl butyral resin shall be the amount of hydroxyl groups 25 mol% or more. This is because the polyvinyl butyral resin having a hydroxyl group content of 25 mol% or more forms a thick resin film at the tip of the tip when the tip of the tip is left in the air, and covers the gap between the ball and the tip of the tip. This is because ink drooping can be suppressed. On the other hand, a polyvinyl butyral resin having a hydroxyl group content of less than 25 mol is not sufficiently soluble in an organic solvent and is not a uniform resin film, so that it is difficult to obtain a sufficient effect of suppressing ink dripping. It is because it is preferable to use this polyvinyl butyral resin. Moreover, 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, during writing, frictional heat is generated by the rotation of the ball, the ink at the tip of the chip is warmed, and the temperature of the ink increases, but the polyvinyl butyral resin is different from other resins, Even if the ink temperature rises, it has the property of making it difficult to lower the ink viscosity, and an ink layer that is always elastic is formed between the ball and the ball seat, making it difficult to make direct contact. It tends to be easy. In particular, oil-based ballpoint pens are effective with oil-based ballpoint pens because writing is often performed with high writing pressure. Further, when a polyvinyl butyral resin having a hydroxyl group content exceeding 40 mol% is used, the amount of moisture absorption tends to increase, and the temporal stability with the oil-based ink component tends to be affected. Therefore, a polyvinyl butyral resin having a hydroxyl amount of 30 to 40 mol% is preferable, and a hydroxyl group amount of 30 to 36 mol% is more preferable.
The hydroxyl content (mol%) of the polyvinyl butyral resin is the content of hydroxyl groups (mol%) with respect to the total molar amount of butyral groups (mol%), acetyl groups (mol%), and hydroxyl groups (mol%). Indicates the rate.

  Further, regarding the average degree of polymerization of the polyvinyl butyral resin, when the average degree of polymerization is 200 or more, the ink drooping performance is improved and the cohesive force of the ink can be increased, so that the ink can easily be placed on the ball surface. When ink remains in the ink, the ink tends to enter between the ball and the ball seat, so that the ball is less likely to come into direct contact with the ball seat, which tends to improve the writing quality. On the other hand, when the average degree of polymerization exceeds 2000, the ink viscosity tends to be too high and the writing quality tends to be affected. Therefore, the average degree of polymerization is preferably 200 to 2000. Further, considering the stability of the basic dye and the salt-forming dye of resin acid, the average degree of polymerization is preferably 1500 or less, and if considering the writing quality, the average degree of polymerization is 1200 or less. Is preferred. Therefore, the average degree of polymerization is preferably 200 to 1500, and more preferably the average degree of polymerization is most preferably 200 to 1000. Here, the average degree of polymerization means the number of basic units constituting one molecule of the polyvinyl butyral resin, and a value measured based on the method defined in JIS K6728 (2001 version) can be adopted. .

  In consideration of ink drooping performance, when a glycol ether solvent is used as the organic solvent, the solubility of the polyvinyl butyral resin is stabilized, and the effect of forming a resin film at the tip of the polyvinyl butyral resin is obtained. In particular, a polyvinyl butyral resin having a hydroxyl group content of 25 mol% or more is preferable because the effect of forming a resin film is easily obtained.

  As for the polyvinyl butyral resin, specifically, trade names manufactured by Sekisui Chemical Co., Ltd .; ESREC BH-3 (hydroxyl group amount: 34 mol%, average degree of polymerization: 1700), BH-6 (hydroxyl group amount: 30 mol%). , Average polymerization degree: 1300), BX-1 (hydroxyl group amount: 33 ± 3 mol%, average polymerization degree: 1700), BX-5 (hydroxyl group quantity: 33 ± 3 mol%, average polymerization degree: 2400), BM -1 (hydroxyl group amount: 34 mol%, average degree of polymerization: 650), BM-2 (hydroxyl group amount: 31 mol%, average degree of polymerization: 800), BM-5 (hydroxyl group amount: 34 mol%, average degree of polymerization: 850) ), BL-1 (hydroxyl group amount: 36 mol%, average polymerization degree: 300), BL-1H (hydroxyl group amount: 30 mol%), BL-2 (hydroxyl group amount: 36 mol%, average polymerization degree: 450), Same B L-2H (hydroxyl content: 29 mol%), BL-10 (hydroxyl content: 28 mol%), etc., trade name of Kuraray Co., Ltd .; Mobital B20H (hydroxyl content: 26-31 mol%, average degree of polymerization: 250) -500), 30T (hydroxyl group amount: 33-38 mol%, average polymerization degree: 400-650), 30H (hydroxyl group amount: 26-31 mol%, average polymerization degree: 400-650), 30HH (hydroxyl group amount: 30-34 mol%, average polymerization degree: 400-650), 45H (hydroxyl group amount: 26-31 mol%, average polymerization degree: 600-850), 60T (hydroxyl group amount: 34-38 mol%, average polymerization degree: 750) -1000), 60H (hydroxyl group amount: 26-31 mol%, average degree of polymerization: 750-1000), 75H (hydroxyl group amount: 26-31 mol%, average degree of polymerization: 1). 00-1750), and the like. You may use these individually or in mixture of 2 or more types.

  If the content of the polyvinyl butyral resin is less than 3.0% by mass relative to the total amount of the ink composition, the amount of resin film formation may be insufficient, and the ink drooping performance tends to be inferior, and exceeds 40.0% by mass. Since the solubility in the ink tends to be inferior, 3.0 to 40.0% by mass is preferable with respect to the total amount of the ink composition. Furthermore, if considering the ink drooping performance, 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 tends to be affected. 0% by mass is preferable, and when considering more, 7.0 to 25.0% by mass is most preferable.

  As the resin other than the polyvinyl butyral resin, an ink viscosity adjusting resin or a spinnability imparting resin may be appropriately used. In particular, it is preferable to contain a spinnability-imparting resin, because by adding a spinnability-imparting resin, the binding property of the ink is improved and the occurrence of excess ink (crying mottling) at the tip of the chip is easily suppressed. As the spinnability-imparting resin, polyvinyl pyrrolidone is preferable, and specifically, trade names of IP Japan Co., Ltd .; PVP K-15, PVP K-30, PVP K-90, PVP K-120, etc. Is mentioned. You may use these individually or in mixture of 2 or more types.

  The content of the spinnability imparting resin used in the present invention is preferably 0.1 to 15.0% with respect to the total resin content in the ink composition. When the content of the spinnability imparting resin is less than 0.1% of the total resin content, there is a tendency that it is difficult to suppress the generation of excess ink (crying blur), and when it exceeds 15.0%, The effect of polyvinyl butyral resin tends to be hindered. Specifically, it inhibits the formation of a resin film on the tip of the chip, making it difficult to suppress ink drooping, and also preventing the formation of a flexible ink layer. This is because the effect of improving the writing quality is difficult to obtain. Considering the tendency to suppress excess ink, the content of the spinnability imparting resin is preferably 1.0 to 15.0% with respect to the total resin content, and ink drooping performance and writing quality are improved. Considering the tendency, 1.0 to 10.0% is preferable, and further considering the tendency, 2.0 to 7.0% is preferable.

  In addition, when an oil-based ballpoint pen is used, it is preferable to use a phosphate ester surfactant in order to maintain lubricity even under high writing pressure (writing load 400 gf) and suppress wear of the ball seat. This is because, in the phosphate ester-based surfactant, the phosphate group is easily adsorbed on the metal surface, the lubricity between the ball and the chip body is maintained, and the writing quality is easily improved. In particular, in the case of using the polyvinyl vinyl butyral resin, the ink layer and the phosphoric acid group formed with the polyvinyl vinyl butyral resin are more preferable because the lubricity is easily improved, and even under high writing pressure (writing load 400 gf). It becomes easy to keep lubricity.

  The acid value of the phosphate ester-based surfactant is preferably 100 or less, which improves the stability of the salt-forming dye of the basic dye and the resin acid by neutralizing and stabilizing with an organic amine. In order to facilitate the improvement of lubricity due to the phosphate ester surfactant. In view of the stability and lubricity of the salt-forming dye, the acid value is preferably 30 to 100, and more preferably the acid value is 50 to 90.

  Furthermore, phosphate ester surfactants tend to soften the formed film, and may improve the writing performance during dry-up. In particular, when the polyvinyl butyral resin is used, the formed film tends to be inferior in writing performance at the time of dry-up, and when a phosphate ester type surfactant is used, the formed film is softened and the writing is improved. Among them, the number of carbon atoms contained in the alkyl group is preferably 12-18, and more preferably, the number of carbon atoms is more preferably 12-15. In particular, in the in / out type writing tools such as knock type writing tools and rotary feeding type writing tools, since the pen tip is always exposed to the outside unlike the cap type writing tools, it tends to affect the writing performance at the time of dry-up, It is more preferable to use a phosphoric ester surfactant.

  Further, when a secondary amine or tertiary amine is used as the phosphate ester surfactant and the organic amine, an alcohol solvent is preferably used. This is because the phosphate ester surfactant and the secondary amine are used. It is easy to maintain a stable neutralized state with amines or tertiary amines, and the salt-forming dyes of the basic dyes and resin acids are dissolved and stabilized, so that there is no deposit and it is easy to obtain long-term ink aging stability. In view of more stability, it is preferable to use a tertiary amine.

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

  Phosphate ester surfactants include polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphate monoester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphate diester, polyoxyethylene alkyl ether Or phosphoric acid triesters, alkyl phosphoric acid esters, alkyl ether phosphoric acid esters or derivatives thereof of polyoxyethylene alkylaryl ethers, and the alkyl group of the phosphoric acid ester type surfactant includes styrenated phenol type, nonylphenol type Type, lauryl alcohol type, tridecyl alcohol type, octylphenol type and the like. These phosphate ester surfactants may be used alone or in combination of two or more.

Specific examples of the phosphate ester surfactant include Prisurf A217E (alkyl group: 14 carbon atoms, acid value: 45 to 58), A219B from the Prisurf series (Daiichi Kogyo Seiyaku Co., Ltd.). (Alkyl group: carbon number 12, acid value: 44 to 58), A215C (alkyl group: carbon number 12, acid value: 80 to 95), A208B (alkyl group: carbon number 12, acid value: 135 to 155) ), A208N (alkyl group: mixture of 12 and 13 carbon atoms, acid value: 160 to 185), phosphanol series (manufactured by Toho Chemical Co., Ltd.), phosphanol RB410 (alkyl group: carbon) No. 18, acid value: 80 to 90), RS-610 (alkyl group: carbon number 13, acid value: 75 to 90), RS-710 (alkyl group: carbon number 13, acid value: 55 to 75) And the like. These surfactants may be used alone or in combination of two or more.
In addition, about an acid value, it shall represent with the mg number of potassium hydroxide required in order to neutralize the acidic component contained in 1g of samples.

  Further, when the total amine value of the organic amine is X and the acid value of the phosphate ester surfactant is Y, it is preferable that 0.1 ≦ Y / X ≦ 7. If it is within the above range, it is easy to improve the stability and lubricity of the salt-forming dye with the basic dye and the resin acid by neutralizing and stabilizing with the organic amine. When considering stability, 0.1 ≦ Y / X ≦ 5 is preferable, and when further considering, 0.1 ≦ Y / X ≦ 3 is preferable, and most preferably 0.1 ≦ Y / X ≦ 1 is there.

  In addition, in order to improve lubricity, as surfactants, fluorine surfactants, silicone surfactants, fatty acid alkanolamides, anionic surfactants and / or cationic surfactants are used. As a stabilizer, fatty acids as viscosity modifiers, pseudoplasticity imparting agents such as fatty acid amides and hydrogenated castor oil, and colorant stabilizers, plasticizers, chelating agents, water, etc. as appropriate It may be used. These may be used alone or in combination of two or more.

  Further, when the oil-based ink composition for writing instruments as described in the present invention newly contains a salt-forming dye of a basic dye and a resin acid, the ink aging stability can be maintained by, for example, moisture absorption during production or aging. Since the oil-based ink contains water, it is preferable to pay attention to the pH value. In order to maintain the ink aging stability of the oil-based ink composition for writing instruments, the pH value is preferably 4.0 to 10.0. This is because if the pH value is 3.9 or less, the metal ions in the chip body are likely to elute, so metal salt precipitates are likely to occur with the salt-forming dye, and if the pH value is 10.1 or more, This is because the ionic bond of the salt-forming dye tends to be separated, and the ink aging stability and the color tone tend to be easily affected. Furthermore, considering the ink aging stability, the pH value is preferably 5.0 to 9.0.

  In addition, in the measuring method of the oil-based ink composition for a writing instrument, the pH value in the present invention is obtained by collecting the oil-based ink in a container, adding ion-exchanged water, heating with stirring, allowing to cool after heating, After replenishing the amount of water evaporated, filter using filter paper. Using the upper layer of the filtered filtrate, pH measurement shows a value measured at 20 ° C. using an IM-40S pH meter manufactured by Toa DKK Corporation.

The ink viscosity of the oil-based ink composition for writing instruments of the present invention is not particularly limited, but the ink viscosity at 20 ° C. and a shear rate of 5 sec ⁻¹ is preferably 10 to 30000 mPa · s. This is because it is difficult to suppress ink sag when the ink viscosity is less than 10 mPa · s, and when the ink viscosity at 20 ° C. and a shear rate of 5 sec ⁻¹ exceeds 30000 mPa · s, the lubricity tends to be poor. . Furthermore, the ink viscosity is more preferably 5000 to 25000 mPa · s in consideration of further improving the ink sag and writing quality, and more preferably 10,000 to 20000 mPa · s.

  By the way, when a polyvinyl butyral resin is used, the content of the polyvinyl butyral resin is 50% or more based on the total resin content in the ink composition, and the ink viscosity is 5000 to 25000 mPa · s. Therefore, it is preferable because the ink dripping performance is remarkably improved. It is necessary to have a structure that suppresses ink sag by constantly pressing the ball against the inner wall surface of the tip of the tip with a coil spring or the like in the tip body and closing the minute gap between the ball and the tip of the tip as in the past. Since the ink dripping suppression effect is obtained, it is not necessary to provide a coil spring or the like in the chip body, which leads to a decrease in the number of parts, and can be suitably used for a retractable type and / or a low-priced product.

  Moreover, it is preferable that the moving amount | distance of the vertical axis | shaft direction of the ball | bowl of the ball-point pen tip used for this invention shall be 3-20 micrometers. This is because if it is less than 3 μm, it becomes difficult to obtain a dark handwriting and good writing taste, and if it exceeds 20 μm, it tends to affect the ink drooping performance. In consideration of the above, 5 to 12 μm is preferable.

  The arithmetic average roughness (Ra) of the ball surface of the ballpoint pen tip used in the present invention is preferably 0.1 to 15 nm. This is because when the arithmetic average roughness (Ra) is less than 0.1 nm, it is difficult to place ink sufficiently on the surface of the ball, and it is difficult to obtain a dark handwriting at the time of writing. When the roughness (Ra) exceeds 15 nm, the ball surface is too rough, and the rotational resistance between the ball and the ball seat is large, so the writing quality tends to be inferior, and the writing performance such as blurring, line skipping, and line unevenness in the handwriting. It is because it becomes easy to have an influence on. In particular, when the average degree of polymerization of the polyvinyl butyral resin is 1500 or less, it is more preferable because the ink is easily placed on the surface of the ball having the arithmetic average roughness (Ra) of 0.1 to 10 nm. Furthermore, in consideration of the ease of placing an ink comprising a salt-forming dye of an acid metal-containing dye and an amine having an aromatic ring used in the present invention or a polyvinyl butyral resin, 1 to 9 nm is preferable, and more preferably 2 ~ 8 nm. In addition, the measurement of surface roughness can be calculated | required by (model name SPI3800N by Seiko Epson Corporation).

  The material used for the ball is not particularly limited, but a cemented carbide ball mainly composed of tungsten carbide, a metal ball such as stainless steel, a ceramic such as silicon carbide, silicon nitride, alumina, silica, zirconia, etc. Ball, ruby ball and the like. It is preferable to use ceramic balls in consideration of writing taste, ball seat wear, and stability over time. The diameter of the ball is not particularly limited, but is generally about 0.25 mm to 2.0 mm.

  Examples of the material for the ballpoint pen tip include stainless steel, white metal, brass (brass), aluminum bronze, aluminum and other resin materials, polycarbonate, polyacetal, ABS and other resin materials. In consideration of the properties, a white chip body is preferable, and in consideration of ball seat wear and stability over time, a stainless steel chip body is preferable.

  The ink container used in the present invention is limited in materials that can be employed from the viewpoint of chemical resistance, moisture permeability, air permeability, and the like. In that respect, it is preferable to conventionally use polypropylene as a material. However, when a salt-forming dye of a basic dye and a resin acid used in the present invention and a polyvinyl butyral resin are used, it has a very strong affinity with a polypropylene ink container, and the ink moves in the ink container. , Ink tends to adhere to the inner wall, making it difficult to understand the remaining ink level. Therefore, when polypropylene is used as the ink containing cylinder, it is preferable to treat the inner wall of the ink containing cylinder with silicone. This is because the silicone is applied to the inner wall of the ink storage cylinder so that the polypropylene, which is the storage cylinder material, does not come into direct contact with the ink, but maintains the relationship in which silicone is interposed in the middle, and is stored when the ink moves. It is possible to prevent adhesion to the inner wall of the cylinder.

  Examples of the silicone material include dimethyl silicone, methyl phenyl silicone, methyl hydrogen silicone, alkyl aralkyl silicone, polyether silicone, and high fatty acid ester fatty acid silicone. Among them, adhesion prevention is excellent and non-reactive. In view of the stability of the oil-based ink component, alkylaralkyl silicone is preferable. The most effective application method is to apply uniformly to the inner wall at the time of extrusion.

Formulation Examples 1 and 2
Next, a method for preparing a salt-forming dye composed of a basic dye and a resin acid will be described.
First, water, a basic dye and a resin acid were added and heated, and then dissolved using a disper stirrer, followed by filtration using filter paper, and the residue on the filter paper was dried to obtain a salt-forming dye.

Formulation Examples 3-5
Next, a method for producing a salt-forming dye other than the salt-forming dye of a basic dye and a resin acid will be described.
As shown in the table, salt-forming dyes of Formulation Examples 3 to 5 were obtained in the same procedure as Formulation Example 1 except that the basic dye and the resin acid were changed.

Next, an Example is shown and this invention is demonstrated.
The oil-based ink composition for a writing instrument of Example 1 includes a salt-forming dye as a colorant, a pigment dispersion, dimethylalkylamine as an organic amine, an alcohol solvent, a glycol ether solvent, a polyvinyl butyral resin as an organic solvent, and phosphorus as a lubricant. Polyvinylpyrrolidone is used as an acid ester surfactant and a spinnability-imparting resin, and a predetermined amount is weighed and heated to 60 ° C., and then completely dissolved using a disper stirrer, and an oil-based ink composition for writing instruments Got. Specific blending amounts are as follows.
Ink viscosity was measured at a shear rate of 5 sec ⁻¹ in an environment of 20 ° C. using an AR-G2 (stainless steel 40 mm 2 ° rotor) manufactured by TA Instruments Inc. At 15000 mPa · s. there were.
Moreover, when pH value was measured, it was pH = 7.7.
In Example 1, when the total amine value of the organic amine was X and the acid value of the phosphate ester surfactant was Y, Y / X = 0.28 to 0.34. .

Example 1
Salt-forming dye of Formulation Example 1 15.0% by mass
Salt-forming dye of Formulation Example 2 5.0% by mass
Pigment dispersion 7.0% by mass
Organic amine (dimethylalkylamine) 2.0% by mass
Polyvinyl butyral resin (ESREC BL-1, hydroxyl group content: 36 mol%, average degree of polymerization: 300) 15.0 mass%
Alcohol solvent (benzyl alcohol) 42.0% by mass
Glycol ether solvent (ethylene glycol monophenyl ether) 11.5% by mass
Lubricant (phosphate-based surfactant) 2.0% by mass
Spinnability imparting resin (polyvinylpyrrolidone) 0.5% by mass

Examples 2-15
As shown in the table, the oil-based ink compositions for writing instruments of Examples 2 to 15 were obtained in the same procedure as in Example 1 except that each component of the ink composition and the chip specifications were changed.
In Examples 2 to 15, when the total amine value of the organic amine is X and the acid value of the phosphate ester surfactant is Y, Y / X = 0.28 to 0.39. there were.

Comparative Examples 1-5
As shown in the table, except that each component of the ink composition and the chip specifications were changed, blending was carried out in the same procedure as in Example 1, and oily ink compositions for writing instruments of Comparative Examples 1 to 5 were obtained. The measurement and evaluation results are shown in the table.

Test and evaluation The oil-based ink composition for writing instruments prepared in Examples 1 to 15 and Comparative Examples 1 to 5 was coated with alkyl aralkyl silicone on the inner wall of the ink container (made of polypropylene), and the tip of the ink container was A ballpoint pen tip (moving amount in the vertical axis direction of the ball: 7 μm) in which a ball (φ0.7 mm) having an arithmetic average roughness (Ra) of 3 nm is rotatably mounted is mounted, and the ink storage cylinder has a first embodiment. Oil ballpoint pen ink (0.3g) was directly stored and a ballpoint refill was placed on an oil ballpoint pen (trade name: Rexgrip) manufactured by Pilot Corporation to produce an oil ballpoint pen as a writing test paper. The following tests and evaluations were performed using writing paper JIS P3201.

Ink aging test: The ink in the chip body was observed with a microscope.
Good color with no discoloration, no precipitates
There is no discoloration of the color tone, but there is a slight amount of precipitates ...
There was a discoloration in the color tone, and the color became dull, but there was no practical problem.
Discoloration of the color tone is severe, or precipitates are generated, which may cause handwriting scraping or writing defects.

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

Written taste: A hand-written sensory test was performed and evaluated.
Very smooth ・ ・ ・ ◎
Smooth thing ○○
Somewhat heavy ・ ・ ・ △
Heavy thing

High writing pressure writing test: The wear of the ball seat after the writing test was measured with a running tester with a load of 400 gf, a writing angle of 70 °, and 4 m / min.
Ball seat wear less than 5μm ・ ・ ・ ◎
Ball seat wear is 5 μm or more and less than 10 μm.
Ball seat wear is 10 μm or more and less than 20 μm, but can be written.
Wearing the ball seat is bad and results in poor writing ・ ・ ・ ×

Light resistance test: A spiral writing test was conducted on JIS P3201 writing paper A at a writing speed of 4.5 m / min under the conditions of a writing angle of 70 ° and a writing load of 150 g, and left for 1 hour, and then xenon fade meter X15F. Using (made by Suga Test Instruments Co., Ltd.), irradiation was performed until the blue scale faded to the third grade, and the handwriting was observed.
Does not fade or slightly fades ... ◎
Fading, but at a level where there is no practical problem ・ ・ ・ ○
Level where fading is conspicuous and causes practical problems ・ ・ ・ ×

In Examples 1 to 15, good performance was obtained for both the ink aging test, the ink drooping performance, the writing quality, and the high writing pressure writing test.
In Examples 14 and 15, since a salt-forming dye of an acid metal-containing dye and an amine having an aromatic ring was used, the light resistance was superior to the other examples.
In Example 16, the ball averaged surface roughness (Ra) of 7 nm (φ1.0 mm) was changed to a ballpoint pen tip (moving amount in the vertical axis direction of the ball: 12 μm) that was rotatably held. An oil-based ballpoint pen was prepared using the oil-based ink composition for writing instruments of Example 1, and the same tests and evaluations as in Example 1 were performed. As a result, the performance evaluation was equivalent to that in Example 1.

  In Comparative Examples 1 to 3, since no organic amine was used, precipitates were generated, handwriting blur was generated, and ink aging stability was poor. In addition, it affected the lubricity, and the writing quality and high pressure test were also inferior.

  In Comparative Examples 4 and 5, when a salt-forming dye other than the salt-forming dye of a basic dye and a resin acid was used, the salt-forming dye was not dissolved and stabilized.

  Although not shown in the table, the oil-based ink compositions for writing instruments of each of the examples and comparative examples, when performing a writing test, the ink moves in the ink containing cylinder as the ink is consumed. Since the aralkyl silicone was applied to the inner wall of the ink containing cylinder (made of polypropylene), the ink did not adhere to the inner wall of the ink containing cylinder, so that the remaining amount of ink could be clearly confirmed. On the other hand, when the writing test was performed with a ballpoint pen that was not applied to the inner wall of the ink containing cylinder (made of polypropylene) with silicone using the oil-based ink composition for writing instruments of Example 1, the ink adhered to the inner wall of the ink containing cylinder. It is difficult to understand the remaining amount of ink, and it is preferable to apply silicone.

In the present invention, in order to improve the writing quality, when the ink viscosity at 20 ° C. and the shear rate of 5 sec ⁻¹ is set to a range of 5000 mPa · s or less, the tip of the ball-point pen tip is used to prevent the ink from dripping. The ball held in a freely rotatable manner is pressed against the inner wall of the tip end edge of the chip directly by a coil spring or via a pressing body, and the ink is allowed to flow out by giving a gap between the inner wall of the tip end edge of the ball and the ball by the pressing force at the time of writing. It is preferable to provide a valve mechanism and close a minute gap at the tip of the tip when not in use.

  In the present invention, by providing a lubricating coating layer on the surface of the ball and / or the surface of the contact surface, a synergistic effect between the lubricating coating layer and the fluid lubrication or mixed lubrication by the ink layer described above causes the ball and the inner wall of the chip. This is preferable because the contact resistance can be remarkably reduced and the wear resistance and writing feeling of the contact surface can be remarkably improved.

  The lubricating coating layer used in the present invention includes diamond-like carbon (DLC), tungsten disulfide (WS2), molybdenum disulfide (MoS2), graphite, fluorine-containing polymers such as tetrafluoroethylene (PTFE), silicone, and the like. Conventionally known solid lubricants such as resins can be used as appropriate. The method for coating the lubricating coating layer is not particularly limited, and examples thereof include vacuum deposition, ion deposition, physical vapor deposition, chemical vapor deposition, and vacuum arc deposition. There may be. In particular, among the above-described lubricants, diamond-like carbon (DLC) is most preferably used in consideration of wear resistance and lubricity.

  The present invention can be used as an oil-based ballpoint pen, and more specifically, can be widely used as a cap-type, knock-type, etc. water-based ballpoint pen filled with the oil-based ink composition for writing instruments.

Claims (8)

An oil-based ink composition for a writing instrument, comprising a salt-forming dye of a basic dye and a resin acid, an organic solvent, and an organic amine. The oil-based ink composition for a writing instrument according to claim 1, wherein the basic dye is a triarylmethane skeleton basic dye or a xanthene skeleton basic dye. The oil-based ink composition for a writing instrument according to claim 1 or 2, wherein the organic amine is a secondary amine or a tertiary amine. The oil-based ink composition for a writing instrument according to any one of claims 1 to 3, further comprising a pigment in the oil-based ink composition for a writing instrument. The oil-based ink composition for writing instruments comprises a polyvinyl butyral resin, and the content of the polyvinyl butyral resin is 50% or more based on the total resin content in the oil-based ink composition for writing instruments. The oil-based ink composition for writing instruments according to any one of claims 1 to 4. 6. The oil-based ink composition for a writing instrument according to claim 1, wherein the ink viscosity at 20 ° C. and a shear rate of 5 sec ⁻¹ is 10 to 30000 mPa · s. An oil-based ballpoint pen refill in which the oil-based ink composition for a writing instrument according to any one of claims 1 to 6 is stored in an ink storage cylinder. A retractable oil-based ballpoint pen characterized in that the oil-based ballpoint pen refill according to claim 7 is disposed in a shaft tube so that the oil ballpoint pen refill can be projected and retracted from the tip of the shaft tube.