JP2020066675A - Oil-based ink composition for writing instrument and writing instrument using the same - Google Patents

Abstract

To produce an oil-based ink composition for a writing instrument that enhances writing feeling and suppression of wear of a ball seat by improving lubricity of a writing tip part and is excellent in ink temporal stability and to produce a writing instrument using the oil-based ink composition.SOLUTION: The oil-based ink composition for a writing instrument includes a coloring agent, an organic solvent and a thiophosphate compound.SELECTED DRAWING: None

Description

  The present invention relates to a writing implement oil-based ink composition and a writing implement using the same.

  Writing instruments are apt to affect the writing quality due to the writing resistance between the writing tip and the writing surface during writing.In particular, a ballpoint pen has a metal tip made of stainless steel or the like on the tip and a ball receiving seat for the metal tip. It has a structure in which a transfer ball made of metal such as super-held steel and a ball-point pen tip made up of it are attached to the ink storage cylinder. There were problems such as line skipping, scraping, and poor writing quality, and there was room for improvement.

  In order to solve these problems, a large number of writing tool oil-based ink compositions using various lubricants have been proposed for the purpose of improving lubricity in order to suppress writing resistance between the writing tip and the writing surface during writing. Has been done.

  As an oil-based ink composition using such a lubricant, as an oil-based ink composition using an alkyl β-D-glucoside, JP-A-5-331403 “oil-based ballpoint pen ink”, N-acylamino acid, N-acylmethyl is used. As the one using tauric acid and N-acylmethylalanine, JP-A 2007-176995 "Ink for oil-based ballpoint pen", and the one using polycyclic aromatic compound, JP-A 2013-151594 "For ballpoint pen" "Oil-based inks" and those using dialkyl polysulfide as a lubricant are disclosed in JP-A-2014-88486, "Oil-based inks for ballpoint pens" and the like.

"JP-A-5-331403" "Japanese Patent Laid-Open No. 2007-176995" "Japanese Patent Laid-Open No. 2013-151594" "JP-A-2014-88486"

However, when using various lubricants as in Patent Documents 1 to 4, although the writing resistance can be reduced to some extent between the writing tip portion and the writing surface, it is not sufficient, and in order to improve further, There was room for improvement. In recent years, since the writing pressure is higher than usual (high writing pressure writing ability), when writing on a copy paper, the writing resistance between the tip of the writing and the surface to be written is further reduced, and thus the lubricity is improved. It is required to improve the writing accuracy by improving the writing pressure.
Furthermore, when a new lubricant is used, it has compatibility with other ink components, and the stability over time in the ink is likely to be affected.

  It is an object of the present invention to provide a writing implement oil-based ink composition that improves the writing quality and the wear resistance of the ball seat by improving the lubricity of the writing tip, and a writing implement using the same.

MEANS TO SOLVE THE PROBLEM This invention contains the coloring agent, the organic solvent, and the thiophosphoric acid compound in order to solve the said subject, The oil-based ink composition for writing instruments characterized by the above-mentioned.
2. The oil-based ink composition for a writing instrument according to item 1, wherein the thiophosphoric acid compound has at least an S = P bond.
3. 3. The oil-based ink composition for a writing instrument according to item 1 or 2, wherein the thiophosphoric acid compound is a dithiophosphoric acid compound or a thiophosphoric acid compound having an aromatic ring.
4. 4. The content of the thiophosphoric acid compound is 0.1 to 5.0% by mass based on the total mass of the ink composition, according to any one of items 1 to 3. Oil-based ink composition for writing instruments.
5. The oil-based ink composition for a writing instrument according to any one of items 1 to 4, wherein the oil-based ink composition for a writing instrument contains a surfactant.
6. A writing instrument containing the oil-based ink composition for a writing instrument according to any one of items 1 to 5.
7. A ball-point pen tip that rotatably holds a ball is provided at the tip of the ink container, and the oil-based ink composition for a writing instrument according to any one of items 1 to 6 is provided in the ink container. An oil-based ballpoint pen characterized by being stored. ".

  The present invention provides a writing instrument oil-based ink composition that improves the lubricity of the writing tip, improves the writing feel and the abrasion of the ball seat, and particularly improves the lubricity under high writing pressure (writing load of 300 to 500 gf). And the writing instrument using it was able to be obtained.

  In the present specification, “parts”, “%”, “ratio” and the like showing the composition are based on mass unless otherwise specified.

  A feature of the present invention is to provide a writing instrument oil-based ink composition containing a thiophosphoric acid compound. By containing a thiophosphoric acid compound, it is possible to improve the lubricity of the writing tip, improve the writing feel and the lubricity between the ball and the tip body, and suppress the wear of the ball seat. However, the lubricating layer of the thiophosphoric acid compound can maintain the lubricity even under a high writing pressure (writing load of 300 to 500 gf) and suppress the abrasion of the ball seat.

(Thiophosphate compound)
The thiophosphoric acid compound used in the present invention is a compound containing both sulfur (S) and phosphorus (P) atoms in its structure.
Both the sulfur (S) and phosphorus (P) atoms of the thiophosphoric acid compound are adsorbed to the writing tip to cover the contact surface of the writing tip, forming a coating layer of thiophosphoric acid (lubrication). By the layer), a friction reducing action works, and it is possible to suppress the writing resistance of the writing tip portion and improve the writing feel. Further, in the case of a ball-point pen, since it contains both sulfur (S) and phosphorus (P) atoms, it is easily adsorbed to a metal material, and the coating layer (lubrication layer) of thiophosphoric acid formed forms the ball and the tip. By reducing the metal friction with the main body and improving the lubricity, it is possible to suppress the abrasion of the ball seat while improving the writing feel. In particular, unlike conventional lubricants, a higher lubrication effect can be obtained by having both sulfur (S) and phosphorus (P) atoms. Therefore, when used in a ballpoint pen, under high writing pressure (writing load 300 Up to 500 gf), it is possible to maintain the lubricity and to suppress the abrasion of the ball seat even under a high writing pressure (writing load of 300 to 500 gf), which is effective. Particularly, a thiophosphoric acid compound having at least a double bond such as an S = P bond has a strong double bond, and the bond is hard to be broken even under a high writing pressure, and under a high writing pressure (writing load 300 to 500 gf). This is preferable because the effect of suppressing the wear of the ball seat can be more easily obtained.

  The thiophosphoric acid compound used in the present invention includes an organic thiophosphoric acid compound and an inorganic thiophosphoric acid compound. However, when an inorganic substance such as zinc is contained, the specific gravity is large, and therefore the stability in the ink is affected. Compounds are preferred. Further, in consideration of lubricity, it is preferable to use a dithiophosphoric acid compound or a thiophosphoric acid compound having an aromatic ring. Since the dithiophosphoric acid compound has two sulfur (S) atoms, it is more likely to be adsorbed on the tip of the writing and to easily form a coating layer (lubrication layer) of thiophosphoric acid, which is effective and has an aromatic ring. When the thiophosphoric acid compound has an aromatic ring, it is more effective because it is more likely to be adsorbed on the writing tip and a coating layer (lubrication layer) of thiophosphoric acid is easily formed.

Further, among the dithiophosphoric acid compounds and the thiophosphoric acid compounds having an aromatic ring, dithiophosphoric acid esters and triphenylthiophosphoric acid esters are preferable in consideration of lubricity, and in consideration of more lubricity, dithiophosphoric acid esters are sulfur ( S) Since it has two atoms, it is more likely to be adsorbed to the writing tip and form a coating layer (lubrication layer) easily, and it is easy to suppress wear of the ball seat under high writing pressure (writing load 300 to 500 gf), which is preferable. .
Specific examples of the thiophosphoric acid compound and the thiophosphoric acid compound having an aromatic ring include dithiophosphoric acid ester, monothiophosphoric acid ester, triphenylthiophosphoric acid ester, and the like. In general formulas (Formula 1) to (Formula 4), The structure is preferable, and considering the suppression of wear of the ball seat under a high writing pressure (writing load of 300 to 500 gf), the structures of the general formulas (Formula 1) to (Formula 4) are preferable, and sulfur (S) Since the more the number of atoms is, the easier it is to suppress wear of the ball seat under a high writing pressure (writing load of 300 to 500 gf), the structure of the general formulas (Formula 1) to (Formula 2) is preferable.

The content of sulfur (S) in the thiophosphoric acid compound is preferably 0.1 to 30 mass% based on the total mass of the thiophosphoric acid compound. This is because if it is within the above range, it is suitable for improving the lubricity, and it becomes easy to suppress the wear of the ball seat even under a high writing pressure (writing load of 300 to 500 gf), and thus the wear of the ball seat is further reduced. Considering suppression and stability in ink, the content of sulfur (S) is preferably 3 to 25% by mass, and more preferably 15 to 25% by mass, based on the total mass of the thiophosphoric acid compound. .
Further, the content of phosphorus (P) in the thiophosphoric acid compound is preferably 0.1 to 15% by mass, based on the total mass of the thiophosphoric acid compound. This is because if it is within the above range, it is suitable for improving the lubricity, and it becomes easy to suppress the wear of the ball seat even under a high writing pressure (writing load of 300 to 500 gf), and thus the wear of the ball seat is further reduced. Considering suppression and stability in ink, the content of phosphorus (P) is preferably 3 to 15% by mass, and more preferably 7 to 12% by mass, based on the total mass of the thiophosphoric acid compound.

Further, the acid value of the thiophosphoric acid compound is preferably 300 (mgKOH / g) or less, considering that the effect of the present invention is easily obtained by considering the stability in the ink. In consideration of stability in ink, the acid value is preferably 200 (mgKOH / g) or less, and when further considered, the acid value is preferably 100 to 200 (mgKOH / g).
The acid value is expressed in mg of potassium hydroxide required to neutralize the acidic components contained in 1 g of the sample.

  Further, the content of the thiophosphoric acid compound is more preferably 0.1 to 10.0 mass% based on the total mass of the ink composition. If it is less than 0.1% by mass, the desired lubricity tends to be difficult to obtain, and if it exceeds 10.0% by mass, the solubility in ink tends to be poor, and the stability of the ink over time is affected. This is because it tends to occur, and considering that tendency, 0.1 to 5.0 mass% is preferable, and further considering, 0.3 to 3.0 mass% is preferable.

(Colorant)
The colorant used in the present invention is not particularly limited, such as dyes and pigments, and can be appropriately selected and used. The dyes and pigments may be used in combination. The dyes include oil-soluble dyes, acid dyes, basic dyes, metal-containing dyes, and various salt-forming dyes thereof, such as salt-forming dyes of acid dyes and basic dyes, basic dyes and organic acids. Examples thereof include salt-forming dyes with and salt-forming dyes with acid dyes and organic amines. These dyes may be used alone or in combination of two or more. Regarding the dye, specifically, Balifast Black 1802, Balifast Black 1805, Balifast Black 1807, Balifirst Violet 1701, Balifirst Violet 1704, Balifirst Violet 1705, Balifirst Blue 1601, Balifirst Blue 1605, Balifirst. 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, Nigrosine Base EXBP, Nigrosine Base EX, BASE OF BASIC DYES ROB-B, BASE OF BASIC DYES RO6 -B, BASE OF BASIC DYES VPB-B, BASE OF BASIC DYES VB-B, BASE OF BASIC DYES MVB-3 (above, manufactured by Orient Chemical Industry Co., Ltd.), Eisenspiron Black GMH-Special, Eisenspirone 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. P. T. Blue 111, S.I. P. T. Blue GLSH-Special, S.I. P. T. Red 533, S.I. P. T. Orange 6, S.I. B. N. Violet 510, S.I. B. N. Yellow 530, S.I. R. C-BH (above, Hodogaya Chemical Co., Ltd. product) etc. are mentioned.

As the dye, at least a salt-forming dye is preferably used in consideration of the improvement of lubricity and the stability of the ink with the thiophosphoric acid compound in the ink over time. Further, the salt-forming bond is stable and thus stable over time. Considering that the properties 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 an acidic dye with a basic dye, or a salt-forming dye of an acid dye and an organic amine.
Among the salt-forming dyes, in consideration of the improvement of lubricity with a thiophosphoric acid compound, it is preferable to use a salt-forming dye of an organic acid and a basic dye, and among them, an alkylallyl sulfonic acid and a basic dye. It is preferable to use the salt-forming dye of. This is because the structure of alkylallyl sulfonic acid has an aromatic ring and has a sulfo group (-SO ₃ H), so that a phenyl sulfone group forms a lubricating layer that is easily adsorbed to a metal, thereby providing more lubrication. Is preferable because it improves the writing property and suppresses the writing feeling and abrasion of the ball seat. Specifically, specifically, alkylbenzene sulfonic acid, naphthalene sulfonic acid, naphthalene sulfonic acid-formaldehyde condensate, alkyldiphenyl ether disulfonic acid, polyoxyethylene alkyl. Phenyl ether phosphoric acid may be mentioned.
Examples of the alkylbenzene sulfonic acid include dodecyl diphenyl oxide disulfonic acid and dodecyl benzene sulfonic acid, which can be preferably used. However, in consideration of improving lubricity, a sulfo group (—SO ₃ H Dodecyl diphenyl oxide disulfonic acid having a large amount of) is preferable.

Examples of the pigment include inorganic, organic and processed pigments, and specifically, carbon black, aniline black, ultramarine blue, yellow lead, titanium oxide, iron oxide, phthalocyanine-based, azo-based, quinacridone-based, diketo. Examples thereof include pyrrolopyrrole-based, quinophthalone-based, slene-based, triphenylmethane-based, perinone-based, perylene-based, dioxazine-based, metallic pigments, pearl pigments, fluorescent pigments, and phosphorescent pigments.
As the type of pigment, it is preferable to use a pigment selected from carbon black, quinacridone pigments, slene pigments, and diketopyrrolopyrrole pigments in consideration of lubricity due to compatibility with thiophosphoric acid compounds.

Considering lubricity, it is preferable to use a pigment as the colorant. This is because the pigment particles get into the gap between the ball and the chip body, which makes it easier to work like a bearing, and by suppressing metal contact, it improves lubricity, improves writing quality, and wears the ball seat. It is preferable to use a pigment because the effect of suppressing the above is easily obtained. Further, the average particle diameter of the pigment is preferably 1 to 500 nm in consideration of the gap relationship inside the ballpoint pen tip. The thickness is more preferably 10 to 350 nm, further preferably 50 to 300 nm. As in the present invention, the use of a thiophosphoric acid compound can improve the writing quality due to the formed lubricating layer, and thus it is preferable to use a pigment.
Here, the average particle diameter is measured by a laser diffraction method, specifically, using a laser diffraction type particle size distribution measuring instrument (trade name “Microtrac HRA9320-X100”, Nikkiso Co., Ltd.) and using a standard sample or another measuring method. The particle diameter (D50) at a volume cumulative 50% of the particle size distribution measured based on the numerical value calibrated by
In addition, since the pigment exhibits the above-mentioned effects in the dispersed state of the pigment in the ink composition for oil-based ballpoint pens, it is preferable to determine the particle diameter of the dispersed state.

  The total content of the colorant is preferably 5.0 to 45.0 mass% based on the total mass of the ink composition. This is because if it is less than 5.0% by mass, dark handwriting tends to be difficult to obtain, and if it exceeds 45.0% by mass, the solubility in ink tends to be affected. If considering, 7.0 to 35.0 mass% is preferable, and further considering, 10.0 to 30.0 mass%.

(Organic solvent)
As the organic solvent used in the present invention, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol monophenyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol dimethyl ether, 3 -Glycol ether solvent such as methoxybutanol, 3-methoxy-3-methylbutanol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, glycol solvent such as ethylene glycol, benzyl alcohol, methanol, ethanol , 1-propanol, 2- Ink for writing instruments such as alcohol solvents such as ropanol, isopropanol, isobutanol, t-butanol, propanol alcohol, allyl alcohol, 3-methyl-1-butyn-3-ol, ethylene glycol monomethyl ether acetate and other higher alcohols Examples of organic solvents that are commonly used as

  Among these organic solvents, it is preferable to use a glycol ether solvent. This is because the colorant is soluble and stable, and is easily stable in the ink. Furthermore, when a glycol ether solvent is used, it easily absorbs moisture, so the strength of the film formed when the tip of the tip is dried is softened, This is because it is easy to improve the writing performance. Further, it is more effective when used in combination with a surfactant described later, and it is preferable to use an aromatic glycol ether solvent. Alternatively, as the organic solvent other than the glycol ether solvent, it is preferable to use an alcohol solvent, but this is because the alcohol solvent is volatilized and easily dried at the tip of the tip, and the inside of the writing tip (in the tip of the tip) is used. It is preferable to increase the viscosity of the ink so as to suppress the ink leakage from the gap between the writing tip portions and improve the ink leakage suppression performance. Furthermore, since aromatic alcohol such as benzyl alcohol also has the effect of improving lubricity, it is preferably used at least.

  Further, the content of the organic solvent is preferably 10.0 to 70.0 mass% based on the total mass of the ink composition in consideration of improving the solubility, the handwriting drying property, the bleeding and the like. Further, the content of the alcohol solvent is preferably 30.0 to 90.0% by mass, more preferably 50.0%, based on the total mass of all the organic solvents in consideration of the drying property at the tip of the tip. ˜90.0 mass%.

(Surfactant)
In the present invention, it is preferable to use a surfactant in consideration of the above-mentioned lubricity and the improvement of the writing performance when the tip portion of the tip is dried when the tip portion is left in the atmosphere. . 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 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 (excluding thiophosphoric acid compounds). Furthermore, considering the lubricity under high writing pressure (300 to 500 gf), it is preferable to use a phosphate ester type surfactant (excluding the thiophosphate compound), which has the same phosphate skeleton as the thiophosphate compound. By having a strong interaction, the ballpoint pen improves lubricity between the ball and the tip body even under a high writing pressure (300 to 500 gf) to suppress wear of the ball seat, Since it is easy to obtain good handwriting without blurring, it can be used more suitably in the present invention.
In particular, the present invention is more effective because a lubricating effect due to the interaction between the phosphate coating layer (lubrication layer) of the thiophosphoric acid compound and the lubricating layer of the surfactant can be expected. Further, as will be described later, it is preferable to use polyvinyl butyral because the ink layer formed of polyvinyl butyral and the lubricating layer of the above-mentioned surfactant can improve the lubricity more easily.

Regarding the surfactant, it is preferable that the HLB value is 6 to 14 in consideration of improving both the writing performance and the lubricity. This is because when the HLB value exceeds 14, the hydrophilicity is likely to be strong and the solubility in the oil-based ink is likely to be poor, so that it is difficult to obtain the effect of the surfactant and it is difficult to obtain the lubricating effect. . On the other hand, 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, in consideration of lubricity, the HLB value is preferably 12 or less, the HLB value is preferably 6 to 12, and the HLB value is preferably 7 to 12 in consideration of the writing performance.
The HLB can be obtained by the Griffin method, Kawakami method, or the like. In particular, in retractable writing instruments such as knock-type writing instruments and rotary feeding type writing instruments, unlike the cap-type writing instruments, the pen tip is always exposed to the outside, which affects the writing performance when the writing tip is dry. Since it is easy, it is more preferable to use a surfactant having the above HLB value.

Specific examples of the surfactant include fatty acids such as oleic acid, stearic acid, and linoleic acid, and examples of the silicone-based surfactant include dimethyl silicone, methylphenyl silicone, polyether-modified silicone, and higher grade. Examples of the surfactant include fatty acid ester-modified silicone. Perfluoro group butyl sulfonate, perfluoro group-containing carboxylate, perfluoro group-containing phosphate ester, perfluoro group-containing phosphate ester type compound things, perfluoroalkyl betaine, and perfluoroalkyl amine oxide compound, and examples of the phosphoric acid ester surfactant, alkoxyethyl group _{(C n H 2n + 1 OCH} 2 CH 2 O) or alkoxy group _{(C m H 2m + 1} O) with phosphoric acid Telluride, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphoric acid monoester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether phosphoric acid diester, polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether Examples thereof include phosphoric acid triesters, alkyl phosphoric acid esters, alkyl ether phosphoric acid esters and their derivatives.
Further, among the phosphoric acid ester-based surfactants, considering that the lubricity between the ball and the chip body is improved and wear of the ball seat is suppressed even under high writing pressure (300 to 500 gf), the alkoxy is used. It is preferable to use a phosphoric acid ester having an ethyl group (C _n H _{2n + 1} OCH ₂ CH ₂ O) or an alkoxy group (C _m H _{2m + 1} O). Considering it more, an alkoxyethyl group (C _n H _{2n + 1} OCH ₂ CH) is used. Preference is given to using phosphoric acid esters with ₂ O).

  The content of the surfactant is more preferably 0.1 to 5.0 mass% based on the total mass 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 tends to become unstable over time. In consideration of the above, 0.3 to 3.0 mass% is preferable based on the total mass of the ink composition, and more consideration is 0.5 to 3.0 mass%.

(Organic amine)
In the present invention, considering the stability of the thiophosphoric acid compound over time, it is preferable to use an organic amine. Amine having ethylene oxide such as oxyethylene alkylamine and polyoxyethylene alkylamine, alkylamine such as laurylamine and stearylamine, dimethylalkylamine such as distearylamine, dimethyllaurylamine, dimethylstearylamine and dimethyloctylamine Among them, aliphatic amines are listed. Among them, amines having ethylene oxide and alkylamines are preferable in view of stability in ink by suppressing precipitation of thiophosphoric acid compounds, and further consideration, alkylamines are preferable. Furthermore, when a phosphate ester-based surfactant is used, it is preferable to neutralize it and stabilize it in the ink, so that the effect of improving the lubricity and the writing performance can be easily obtained.

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

Further, the total amine value of the organic amine is preferably 100 to 300 (mgKOH / g) in consideration of stability with ink components such as thiophosphoric acid compounds and dyes. When it exceeds 300 (mgKOH / g), it has a strong reactivity and is likely to react with a thiophosphoric acid compound, a dye and other ink components, and thus the ink stability over time tends to be poor. If the total amine value is less than 100 (mgKOH / g), the stability of the components in the ink is likely to be affected, and further, the stability of the ink over time with respect to the thiophosphoric acid compound is likely to be affected, so In that case, the adsorptivity of metals such as balls and chip bodies is likely to be poor, and it is difficult to obtain lubricating performance. The range of 150 to 300 (mgKOH / g) is more preferable in consideration of stability and lubricity with thiophosphoric acid compounds and dyes, and more preferably 200 to 300 (mgKOH / g).
The total amine value indicates 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.

  Specific examples of the organic amines include oxyethylene alkyl amines and polyoxyethylene alkyl amines such as Niimine L-201 (total amine value: 232 to 246, secondary amine) and L-202. (Total amine value: 192-212, tertiary amine), L-207 (total amine value: 107-119, tertiary amine), S-202 (total amine value: 152-166, 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) Primary amine), the same DT-208 (total amine value: 146 to 180, tertiary amine) (manufactured by NOF CORPORATION). Specific examples of the alkylamine include Farmin 80 (total amine value: 204 to 210, primary amine), Farmin D86 (total amine value: 110 to 119, secondary amine), Farmin DM2098 (total amine value: 254). ~ 265, tertiary amine), Pharmin DM8680 (total amine value: 186-197, tertiary amine) (Kao Corporation), Nissan tertiary amine BB (total amine value: 243-263, tertiary amine), the same. FB (total amine value: 230 to 250, tertiary amine) (manufactured by NOF CORPORATION) and the like. 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, based on the total mass of the ink composition, in consideration of the stability with the thiophosphoric acid compound, the dye and other components. Considering the neutralization of the phosphoric acid ester-based surfactant, 0.1 to 5.0% by mass is preferable.

(resin)
Further, in order to further improve the ink leakage suppression, 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, Examples thereof include alkyd resins, phenoxy resins, and polyvinyl acetate resins. Among them, it is preferable that the polyvinyl butyral resin or the ketone resin is contained.

  By using a ketone resin in combination with a thiophosphoric acid compound, synergistic lubricating action is likely to be exerted, and under high writing pressure (writing load of 300 to 500 gf), the lubricity is improved and the abrasion of the ball seat is further suppressed. Therefore, it is preferable. Among the ketone resins, it is preferable to use 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). preferable. This is because the cushioning effect of the ketone resin having a ring structure is obtained, the lubricity is improved under high writing pressure (writing load 300 to 500 gf), and the wear control of the ball seat is further improved, and more preferably, The ketone resin, which is an aromatic ring skeleton, has a large number of double bond structures, and thus a stronger cushioning effect is likely to be obtained. Therefore, lubricity under high writing pressure (writing load 300 to 500 gf) is effective, preferable.

Also for the polyvinyl butyral resin, by using it together with the thiophosphoric acid compound, it is easy to form a lubricating layer having a higher lubricating effect. Therefore, since an ink layer having elasticity is always formed between the ball and the ball seat to make it difficult to make direct contact, it is easy to improve writing quality. Further, when the polyvinyl butyral resin is used, it is preferable because the film to be formed makes it easier to improve ink leakage, and when a pigment is used as a colorant, a pigment dispersion effect is also obtained, so that the polyvinyl butyral resin is used. It is preferable to use.
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 amount of less than 25 mol does not have sufficient solubility in an organic solvent, and it is difficult to obtain a sufficient lubrication effect and an ink leakage suppression effect. Furthermore, considering the writing performance due to hygroscopicity, 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 amount of 30 mol% or more is preferable because the writing feeling is easily improved. This is because at the time of writing, frictional heat is generated by the rotation of the ball, the ink at the tip of the tip is warmed, and the temperature of the ink rises, 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 reduce the ink viscosity.By forming an ink layer that is always elastic between the ball and the ball seat, making it hard to make direct contact, the writing feel is improved. Tends to be easy. In particular, with a ballpoint pen, since writing is often performed with a high writing pressure, it is effective with a writing tool. When a polyvinyl butyral resin having a hydroxyl group content of more than 40 mol% is used, the amount of moisture absorption tends to increase and stability with time of ink components is likely 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 amount of 30 to 40 mol% is preferable, and a hydroxyl group amount of 30 to 36 mol% is more preferable.
The amount of hydroxyl groups (mol%) of the polyvinyl butyral resin means that the content of hydroxyl groups (mol%) is based on the total amount 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 tends to be improved, and when the average degree of polymerization exceeds 2500, the ink viscosity becomes too high. Therefore, the average degree of polymerization is preferably 200 to 2500. Considering further, the average degree of polymerization is preferably 1500 or less, more preferably 1000 or less. Here, the average degree of polymerization refers to the number of basic units constituting one molecule of the polyvinyl butyral resin, and a value measured based on the method specified in JISK6728 (2001 version) can be adopted. .

  The content of the polyvinyl butyral resin is 50% or more based on the total mass of all the resins in the writing instrument composition, and it is preferably used as the main resin. This is because when the content of the polyvinyl butyral resin is less than 50% based on the total mass of all the resins, other resins tend to hinder the formation of an elastic ink layer and improve the writing feel. It becomes difficult to obtain the effect of, and it is easy to hinder the formation of the resin film at the tip of the tip, it is not possible to suppress the ink dripping, and it also hinders the formation of an elastic ink layer, which improves the writing quality. This is because it is difficult to obtain the effect. Considering the tendency of improving the writing quality and the ink dripping performance, the content of the polyvinyl butyral resin is preferably 70% or more, and more preferably 90% or more, based on the total mass of all the resins.

  If the content of the polyvinyl butyral resin is less than 1.0% by mass, based on the total mass of the ink composition, the desired lubricity and the ink leakage suppression performance tend to be poor, and if it exceeds 40.0% by mass, Since the solubility in the ink is likely to be poor, 1.0 to 40.0 mass% is preferable based on the total mass of the ink composition. Furthermore, if considering, 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. preferable.

  Regarding the polyvinyl butyral resin, specifically, trade name of Sekisui Chemical Co., Ltd .; S-REC BH-3 (hydroxyl group amount: 34 mol%, average degree of polymerization: 1700), BH-6 (hydroxyl group amount: 30 mol%) , Average degree of polymerization: 1300), same BX-1 (hydroxyl group amount: 33 ± 3 mol%, average degree of polymerization: 1700), same BX-5 (hydroxyl group amount: 33 ± 3 mol%, average degree of polymerization: 2400), same BM -1 (hydroxyl group amount: 34 mol%, average polymerization degree: 650), BM-2 (hydroxyl group amount: 31 mol%, average polymerization degree: 800), BM-5 (hydroxyl group amount: 34 mol%, average polymerization degree: 850) ), The same BL-1 (hydroxyl group amount: 36 mol%, average degree of polymerization: 300), the same BL-1H (hydroxyl group amount: 30 mol%), the same BL-2 (hydroxyl group amount: 36 mol%, average degree of polymerization: 450), Same B L-2H (hydroxyl group amount: 29 mol%), the same BL-10 (hydroxyl group amount: 28 mol%) and the like, a trade name manufactured by Kuraray Co., Ltd .; Mobital B20H (hydroxyl group amount: 26 to 31 mol%, average degree of polymerization: 250). ~ 500), the same B30T (hydroxyl group amount: 33 to 38 mol%, average degree of polymerization: 400 to 650), the same B30H (hydroxyl group amount: 26 to 31 mol%, average degree of polymerization: 400 to 650), the same B30HH (hydroxyl group amount: 30 to 34 mol%, average degree of polymerization: 400 to 650, B45H (amount of hydroxyl group: 26 to 31 mol%, average degree of polymerization: 600 to 850), B60T (amount of hydroxyl group: 34 to 38 mol%, average degree of polymerization: 750) ~ 1000), the same B60H (hydroxyl group amount: 26 to 31 mol%, average degree of polymerization: 750 to 1000), the same B75H (hydroxyl group amount: 26 to 31 mol%, Hitoshi polymerization degree: 1,500 to 1,750), and the like. You may use these individually or in mixture of 2 or more types.

  For the resins other than the polyvinyl butyral resin and the ketone resin, a spinnability imparting agent may be appropriately used. In particular, the incorporation of the polyvinylpyrrolidone resin enhances the binding property of the ink and makes it easy to suppress the generation of the excess ink at the tip of the chip. Therefore, it is preferable to contain the polyvinylpyrrolidone resin. If the content of the polyvinylpyrrolidone resin is less than 0.01% by mass based on the total mass of the ink composition, it tends to be difficult to suppress the generation of excess ink, so if it exceeds 3.0% by mass, Since solubility in ink tends to be poor, 0.01 to 3.0 mass% is preferable based on the total mass of the ink composition. Considering the above reason, 0.1 to 2.0 mass% is preferable. Specific examples thereof include trade names of PSP K-15, PVP K-30, PVP K-90, and PVP K-120 manufactured by ISPI Japan K.K. You may use these individually or in mixture of 2 or more types.

  In the ink composition for a writing instrument according to the present invention, other additives such as (i) a surfactant, for example, a fatty acid alkanolamide, an anionic surfactant, are added in order to improve lubricity and ink stability over time. , Cationic surfactants, amphoteric surfactants, and (ii) viscosity modifiers such as fatty acid amides, pseudoplasticizers such as hydrogenated castor oil, (iii) colorant stabilizers, (iv) plasticizers An agent, (v) a chelating agent, or (vi) water as a cosolvent may be appropriately used. These may be used alone or in combination of two or more.

  The arithmetic mean roughness (Ra) of the ball surface of the ballpoint pen tip is preferably 0.1 to 12 nm. This is because if the arithmetic average roughness (Ra) is less than 0.1 nm, it is difficult to deposit ink on the surface of the ball, it is difficult to obtain dark handwriting during writing, line strokes are easily generated in the handwriting, and the arithmetic average is 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 the writing quality is likely to be poor, and the writing performance such as scratches, skipped lines, and uneven lines on the handwriting. This is because it is easy to affect. Further, when the arithmetic average roughness (Ra) is 0.1 to 10 nm, it is more preferable when the polyvinyl butyral resin is used because the ink is easily deposited on the ball surface, and if the writing feeling is taken into consideration, it is 2 to 8 nm. Is preferred. 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 a cemented carbide ball containing tungsten carbide as a main component, a metal ball such as stainless steel, or a ceramic such as silicon carbide, silicon nitride, alumina, silica, or zirconia. Examples include balls and ruby balls.
Also, if the ball diameter is a relatively small ball diameter of 0.7 mm or less, the number of rotations of the ball increases as the ball diameter decreases when writing at the same distance. The thiophosphoric acid compound used in the present invention is effective because the wear of the composition is likely to be severe, and when the ball diameter is 0.5 mm or less, under high writing pressure (writing load 300 to 500 gf), It is more effective because the ball seat easily wears.

  Examples of the ball-pen tip material include metal materials such as stainless steel, nickel silver, brass (brass), aluminum bronze, and aluminum, and resin materials such as polycarbonate, polyacetal, and ABS. It is preferable to use a stainless steel chip body in consideration of the property and cost.

The ink viscosity of the writing instrument oil-based ink composition of the present invention is not particularly limited, but if the ink viscosity at 20 ° C. and a shear rate of 5 sec ⁻¹ (at rest) exceeds 50000 mPa · s, the writing performance and writing quality will be improved. The ink viscosity at 20 ° C. and a shear rate of 5 sec ⁻¹ (at rest) is preferably 50,000 mPa · s or less because the ink is inferior. 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 30,000 mPa · s in view of further improving ink leakage suppression, writing quality, ink following performance, and writing performance, and further considering, 5,000 to 20,000 mPa · s. preferable.

Next, the present invention will be described with reference to examples.
The writing instrument oil-based ink composition of Example 1 employs a colorant, an organic solvent, a thiophosphoric acid compound, a phosphate ester-based surfactant, an organic amine, a polyvinyl butyral resin, and polyvinylpyrrolidone, and weighs a predetermined amount of this. After heating to 60 ° C., it was completely dissolved using a Disper stirrer to obtain a writing instrument oil-based ink composition. The specific compounding amount is as follows.
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 RVDVII + Pro CP-52 spindle manufactured by Brookfield Co., Ltd. The ink viscosity was 15000 mPa · s.

Example 1
Coloring agent (salt-forming dye of alkylallyl sulfonic acid and basic dye) 10.0% by mass
Coloring agent (salt forming dye of acid dye and basic dye) 5.0% by mass
Alcohol solvent (benzyl alcohol) 30.5% by mass
Glycol ether solvent (ethylene glycol monophenyl ether) 35.0% by mass
Dithiophosphoric acid ester (Chemical 1: Sulfur 19.8 mass% content, phosphorus 9.3 mass% content, acid value 140 (mgKOH / g) 1.0 mass%
Phosphoric acid ester surfactant (phosphate ester having an alkoxy ethyl group _{(C n H 2n + 1 OCH} 2 CH 2 O) surfactant) 1.0 wt%
Organic amine 2.0 mass%
Polyvinyl butyral resin (hydroxyl group amount: 36 mol%, average degree of polymerization: 300) 15.0% by mass
Spinnability imparting resin (polyvinylpyrrolidone resin) 0.5% by mass

Examples 2-15
As shown in the table, the ink was compounded in the same procedure as in Example 1 except that each component was changed to obtain the writing implement oil-based ink compositions of Examples 2 to 15. The measurement and evaluation results are shown in the table.
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Comparative Examples 1-3
As shown in the table, the writing tool oil-based ink compositions of Comparative Examples 1 to 3 were obtained in the same procedure as in Example 1 except that each component was changed. The measurement and evaluation results are shown in the table.

Tests and Evaluations A ballpoint pen tip in which the writing tool oil-based ink compositions prepared in Examples 1 to 15 and Comparative Examples 1 to 3 were rotatably held by a ball (φ0.5 mm) at the tip of an ink container (made of polypropylene). The ballpoint pen refill is directly stored in the ink container and the ink for the oil-based ballpoint pen of Example 1 (0.2 g) is refilled, and an oil-based ballpoint pen manufactured by Pilot Corporation (trade name: Super Grip (registered (Trademark)), an oil-based ballpoint pen was produced, and the following tests and evaluations were performed using writing paper JIS P3201 as a writing test paper.

Abrasion resistance test under high writing pressure (ball seat wear test): The wear of the ball seat after the writing test was measured by a running tester with a load of 400 gf, a writing angle of 70 °, and 4 m / min.
The ball seat wear is less than 3 μm.
Abrasion of the ball seat is 3 μm or more and less than 5 μm ... ◎
The ball seat wear is 5 μm or more and less than 10 μm.
The ball seat wear is 10 μm or more and less than 20 μm, but it is writable ... △
The ball seat is badly worn, resulting in poor writing ... ×

Writing quality: A sensory test by handwriting was performed and evaluated.
Very smooth ... ◎
What is smooth ・ ・ ・ ○
Those with a level of smoothness that is practically no problem ... △
Heavy things ... ×

Ink aging test: In the environment of 50 ° C., the ink in the chip body was observed with a microscope after one month.
Good with no precipitates ・ ・ ・ ◎
Precipitate was generated, but there is no problem in practical use ... ○
Precipitates are generated, causing scratches and poor writing ... ×

  In Examples 1 to 15, good performances were obtained in the abrasion resistance test under high writing pressure (ball seat abrasion test), writing quality, and ink aging test.

  In Comparative Examples 1 to 3, since no thiophosphoric acid compound was used, in the abrasion resistance test under high writing pressure (ball seat abrasion test), the ball seat was badly worn, and some scratches were generated on the handwriting, resulting in poor writing. It was Furthermore, in Comparative Examples 1 and 2, the writing quality was poor.

    Further, in the present example, the oil-based ballpoint pen in which the ballpoint pen refill containing the writing implement oil-based ink composition in the ink containing cylinder is arranged in the barrel is illustrated, but the writing implement of the present invention is configured such that the barrel itself is the ink containing barrel. In addition, the shaft cylinder may be a writing tool such as a direct-packing type ball-point pen, a marking pen, and a felt-tip pen that directly accommodates the writing implement oil-based ink composition, and the writing implement oil-based ink composition is accommodated in the ink containing barrel. A structure in which the (ball-point pen refill) is used as it is as a ball-point pen may be used.

  INDUSTRIAL APPLICABILITY The present invention can be used as a writing implement oil-based ink composition, and more specifically, it can be widely used as a cap-type, knock-type writing implement filled with the writing implement oil-based ink composition.

Claims (7)

An oil-based ink composition for a writing instrument, comprising a colorant, an organic solvent, and a thiophosphoric acid compound. The oil-based ink composition for a writing instrument according to claim 1, wherein the thiophosphoric acid compound has at least an S = P bond. The oil-based ink composition for a writing instrument according to claim 1 or 2, wherein the thiophosphoric acid compound is a dithiophosphoric acid compound or a thiophosphoric acid compound having an aromatic ring. Content of the said thiophosphoric acid compound is 0.1-5.0 mass% on the basis of the total mass of an ink composition, The writing instrument of any one of Claim 1 thru | or 3 characterized by the above-mentioned. Oil-based ink composition. The oil-based ink composition for a writing instrument according to any one of claims 1 to 4, wherein the oil-based ink composition for a writing instrument contains a surfactant. A writing instrument containing the oil-based ink composition for a writing instrument according to any one of claims 1 to 5. A ball-point pen tip that rotatably holds a ball is provided at the tip of the ink container, and the oil-based ink composition for a writing instrument according to any one of claims 1 to 6 is housed in the ink container. An oil-based ballpoint pen characterized by