Oil-based ballpoint pen ink composition and oil-based ballpoint pen using the same

Abstract

The object of the present invention is to obtain an oil-based ballpoint pen ink composition and an oil-based ballpoint pen using the same, which suppresses ball skipping when writing with a ballpoint pen, thereby suppressing the occurrence of skipped lines and smudged lines in the handwriting, and resulting in good handwriting. [Solution] An oil-based ballpoint pen ink composition comprising a colorant, an organic solvent, and a maleic acid copolymer, wherein the maleic acid copolymer is a styrene-maleic anhydride copolymer or an olefin-maleic acid copolymer.

Description

[Technical Field]

[0001] This invention relates to an oil-based ballpoint pen ink composition and an oil-based ballpoint pen using the same. [Background technology]

[0002] Oil-based ballpoint pens, which use oil-based ink, have been known for a long time and are used by a wide range of age groups due to their ease of use. These oil-based ballpoint pens are made possible by containing colorants, solvents, surfactants, etc., which enable them to write well on paper. (Patent Document 1)

[0003] Some ballpoint pens have issues where the ink doesn't adhere sufficiently to the ball during writing, causing the ball to not rotate properly and resulting in skipped or streaky lines in the writing. There was room for improvement. (Patent Document 1)

[0004] Furthermore, oil-based ballpoint pens are susceptible to writing resistance between the writing tip and the writing surface during writing, which can affect the writing feel. An oil-based ballpoint pen has a ballpoint tip consisting of a metal tip made of stainless steel or the like, and a transfer ball made of metal such as carbide held in the ball seat of the metal tip, which is mounted in an ink reservoir. During writing, the rotation of the ball can degrade the writing feel, sometimes causing skipped lines or fading in the handwriting, indicating room for improvement.

[0005] To address these issues, numerous ink compositions for writing instruments have been proposed that utilize various lubricants to improve lubrication and suppress writing resistance between the writing tip and the writing surface during writing. (Patent Documents 2-4) [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. Hei 8-41406 [Patent Document 2] Japanese Patent Application Publication No. 5-331403 [Patent Document 3] Japanese Patent Publication No. 2007-176995 [Patent Document 4] Japanese Patent Publication No. 2010-150337 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, while using various new lubricants can reduce writing resistance between the ballpoint pen's ball and the writing surface to some extent, and improve writing feel, some ballpoint pens still cause the ball to skip, resulting in skipped or streaky lines in the writing, leaving room for improvement (Patent Documents 2-4).

[0008] The object of the present invention is to obtain an oil-based ballpoint pen ink composition that suppresses skipped lines and smudging in handwriting, thereby improving the quality of the handwriting, and an oil-based ballpoint pen using the same. [Means for solving the problem]

[0009] To solve the above problems, the present invention "1. An oil-based ballpoint pen ink composition comprising a colorant, an organic solvent, and a maleic acid copolymer, wherein the maleic acid copolymer is a styrene-maleic anhydride copolymer or an olefin-maleic acid copolymer." 2. The oil-based ballpoint pen ink composition according to paragraph 1, characterized in that the content of the maleic acid copolymer is 0.1 to 5% by mass with respect to the total amount of the ink composition. 3. The oil-based ballpoint pen ink composition according to paragraph 1 or 2, characterized in that the organic solvent is selected from an alkylene oxide derivative of glycerin, an alkylene glycol alkyl ether solvent, an amide solvent, and an aromatic alcohol. 4. The oil-based ballpoint pen ink composition according to paragraph 1 or 2, characterized in that the oil-based ballpoint pen ink composition contains an organic amine. 5. The ink composition for an oil-based ballpoint pen according to claim 1 or 2, characterized in that it contains a surfactant. 6. An oil-based ballpoint pen, characterized in that it contains the ink composition for an oil-based ballpoint pen according to claim 1 or 2.

Advantages of the Invention

[0010] According to the present invention, when writing with a ballpoint pen, the ball can rotate stably, thereby suppressing ball skipping, suppressing streaks and smears in the handwriting, and obtaining an oil-based ballpoint pen ink composition with good handwriting. An oil-based ballpoint pen using the same can be obtained.

Embodiments for Carrying Out the Invention

[0011] In this specification, "parts", "%", "ratio", etc. indicating formulation are based on mass unless otherwise specified.

[0012] The feature of the present invention is an ink composition for an oil-based ballpoint pen, characterized in that it contains a colorant, an organic solvent, a styrene maleic anhydride copolymer or an olefin maleic acid copolymer. This contains a styrene maleic anhydride copolymer or an olefin maleic acid copolymer, which can suppress ball skipping, suppress streaks and smears in the handwriting, and improve the handwriting. Furthermore, even on printed matter formed with printing ink such as toner, ball skipping can be suppressed, streaks and smears in the handwriting can be suppressed, and good writing performance can be obtained, which is preferable.

[0013] (Maleic acid copolymer) For the maleic acid copolymer used in the present invention, a styrene maleic anhydride copolymer or an olefin maleic acid copolymer is used. Regarding the styrene maleic anhydride copolymer, the styrene maleic anhydride copolymer is a binary copolymer (copolymer) produced by copolymerizing a styrene monomer and maleic anhydride, and is an anhydride having two or more acid anhydride groups. Further, due to the difference in the arrangement of the styrene monomer and maleic anhydride, the styrene maleic anhydride copolymer is classified into an alternating copolymer, a random copolymer, a block copolymer, and a graft copolymer. Any of these copolymers may be used. Regarding the olefin maleic acid copolymer, it is a binary copolymer (copolymer) produced by copolymerizing an olefin and maleic anhydride.

[0014] Also, by including the styrene maleic anhydride copolymer or the olefin maleic acid copolymer, when writing with a ballpoint pen, the ball can rotate stably, suppressing the skipping of the ball, suppressing streaks and smears in the handwriting, and making the handwriting good. In particular, anhydrides such as the styrene maleic anhydride copolymer are likely to maintain stability in the oil-based ink, and thus the effects such as those of the present invention are easily obtained, which is preferable.

[0015] Further, the maleic acid copolymer can also be preferably used as a salt of the styrene maleic anhydride copolymer or a salt of the olefin maleic acid copolymer. Specifically, salts of the styrene maleic anhydride copolymer or salts of the olefin maleic acid copolymer such as sodium salts, ammonium salts, and potassium salts may be used. In particular, regarding the olefin maleic acid copolymer, considering maintaining stability in the ink and the effect of suppressing streaks and smears in the handwriting, a salt of the olefin maleic acid copolymer is preferable, and more preferably, a sodium salt of the olefin maleic acid copolymer is preferable.

[0016] Regarding the olefin maleic acid copolymer, considering that the ball can rotate stably, suppressing the skipping of the ball and the effect of suppressing streaks and smears in the handwriting, a trimethylpentene maleic acid copolymer is preferable.

[0017] The content of styrene-maleic anhydride copolymer salt or olefin-maleic acid copolymer salt is more preferably 0.1% by mass or more and 10% by mass or less, relative to the total amount of the ink composition. This is because if it is less than 0.1% by mass, it is difficult to obtain the desired effect of suppressing line skipping and smudging in the handwriting, and if it exceeds 10% by mass, the ink tends to become unstable over time. Considering this further, it is preferable that the content be 0.1% by mass or more and 5% by mass or less, relative to the total amount of the ink composition, preferably 0.3% by mass or more and 5% by mass or less, and preferably 0.5% by mass or more and 3% by mass or less.

[0018] (Organic solvents) Organic solvents can improve color development while ensuring the solubility and stability of ink components, and can also improve writing performance by suppressing skipped lines, smudging, and blotting in the handwriting. Specifically, examples of organic solvents include alkyl ethers such as alkylene glycol monoalkyl ethers and alkylene glycol dialkyl ethers; amide solvents such as β-alkoxypropionamides such as 3-methoxy-N,N-dimethylpropanamide, 3-butoxy-N,N-dimethylpropanamide, and 3-ethoxy-N,N-dimethylpropanamide; alkylene oxide derivatives of glycerin such as polyoxyalkylene glyceryl ether, polyoxyalkylene alkyl glucoside, and polyoxypropylene alkyl ether; glycol solvents such as diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, and ethylene glycol; and alcohol solvents such as benzyl alcohol, methanol, ethanol, 1-propanol, 2-propanol, isopropanol, isobutanol, t-butanol, propagyl alcohol, allyl alcohol, 3-methyl-1-butyne-3-ol, ethylene glycol monomethyl ether acetate, and other higher alcohols.

[0019] Among these organic solvents, it is preferable to select from alkylene oxide derivatives of glycerin, alkylene glycol alkyl ethers, amide solvents, and aromatic alcohols, considering that the effects of the present invention are easily exhibited due to their compatibility with the maleic acid copolymer. Furthermore, considering that stable rotation of the ball suppresses ball skipping and reduces skipping and smudging of handwriting, it is preferable to select from alkylene glycol alkyl ethers, amide solvents, alkylene oxide derivatives of glycerin, and aromatic alcohols. Moreover, considering that it is easier to improve lubricity, maintaining lubricity between the writing tip and the writing surface (lubricity between the ball and the tip body), suppressing writing resistance at the writing tip, suppressing wear of the ball seat under high writing pressure (writing load of 300-500 gf), and improving writing feel, it is preferable to select an alkylene oxide derivative of glycerin. These organic solvents may be used individually or in combination of two or more, but it is preferable to select two.

[0020] Furthermore, in the case of the present invention, which includes a maleic acid copolymer, the film formation can easily affect the writing performance. Using an alkylene oxide derivative of glycerin is preferable because it makes it easier to soften the film, thus improving the writing performance. Furthermore, it is preferable because it suppresses skipped lines and smudging in handwriting even on printed areas formed with toner or other printing inks, thereby achieving good writing performance.

[0021] As an alkylene oxide derivative of glycerin, polyoxyalkylene glyceryl ether is preferred, considering that it improves writing performance while also improving slipperiness, thereby suppressing skipped lines and smudged writing, and reducing wear on the ball seat.

[0022] Furthermore, polyoxyalkylene glyceryl ethers are obtained by addition polymerization of alkylene oxide to glycerin or polyglycerin, and examples include polyoxyalkylene glyceryl ether, polyoxyalkylene diglyceryl ether, and polyoxyalkylene triglyceryl ether.

[0023] Furthermore, when pigments are used as colorants, the ink viscosity generally increases over time due to pigment aggregation, which tends to reduce ink followability. However, the polar groups within the structure of the alkylene oxide derivative of glycerin adsorb to the pigment surface, stably dispersing the pigment in the ink. This suppresses the increase in ink viscosity due to pigment aggregation, improving ink followability, suppressing skipped lines and smudging in the handwriting, and resulting in good handwriting. Therefore, considering pigment dispersion stability and suppression of skipped lines and smudging, it is preferable to use polyoxyalkylene glyceryl ether, and among these, polyoxyalkylene diglyceryl ether is preferable if these factors are considered more carefully.

[0024] Furthermore, polyoxyalkylene glyceryl ethers include polyoxyethylene glyceryl ether and polyoxypropylene glyceryl ether. Of these, polyoxypropylene glyceryl ether has a propylene group, which gives it excellent lipophilicity and suppresses moisture absorption in the oil-based ballpoint pen ink composition, thereby improving its stability over time and making it easier to obtain the effects of the present invention. For this reason, it is preferable to use polyoxypropylene glyceryl ether.

[0025] Considering that the effects of the present invention can be easily obtained by further improving the slipperiness of the polyoxyalkylene glyceryl ether, which allows the ball to rotate stably, thereby suppressing ball skipping, suppressing line skipping and smudging in the writing, suppressing wear of the ball seat, and improving pigment dispersion stability and aging stability, it is preferable that the average number of added moles of alkylene oxide (average number of added moles of alkylene oxide) is 1 or more and 30 or less, and more preferably 1 or more and 30 or less, and considering further improvement of slipperiness and aging stability, it is preferable that the average number of added moles of alkylene oxide is 1 or more and 20 or less, and more preferably 5 or more and 20 or less.

[0026] In particular, considering that improving the lubricity allows the ball to rotate stably, thereby suppressing ball skipping, reducing line skipping and smudging in the writing, suppressing wear on the ball seat, and improving the writing feel, it is preferable that the average number of moles of propylene oxide added is 1 to 30, more preferably 1 to 20, even more preferably 5 to 20, even more preferably 1 to 12, and particularly preferably 5 to 12. Furthermore, considering that the effects of the present invention are easily exhibited, the structure of the polyoxyalkylene glyceryl ether is preferably represented by the following formula (1) or (2). [ka] In the formula, m, n, o, p, w, x, y, and z are numbers that independently represent the number of alkylene oxide additions. Here, m+n+o+p is the average number of moles of propylene oxide added, and w+x+y+z is the average number of moles of ethylene oxide added.

[0027] Of these, polyoxyalkylene glyceryl ether represented by formula (1) is preferred because it significantly improves stability over time, making it easier to obtain the effects of the present invention.

[0028] Furthermore, the weight-average molecular weight of the alkylene oxide derivative of glycerin is preferably 5000 or less. This is because if the weight-average molecular weight is too high, it tends to affect stability over time, and the viscosity of the oil-based ballpoint pen ink composition tends to increase, which can lead to skipped lines and smudges in the handwriting due to the influence of ink followability. To further consider stability over time and the reduction of skipped lines and smudging in the handwriting due to ink followability, the weight-average molecular weight is preferably 3000 or less, more preferably 1500 or less, and more preferably 1200 or less. Also, to further improve slipperiness and produce good handwriting, it is preferably 900 or less. On the other hand, if the weight-average molecular weight is too low, it tends to affect slipperiness and pigment dispersibility, so it is preferably 300 or more, and to further consider this, it is preferably 500 or more. The weight-average molecular weight is a value obtained using GPC (gel permeation chromatography) in terms of polystyrene equivalent.

[0029] Furthermore, regarding alkylene glycol monoalkyl ethers, considering the ease with which the alkylene glycol portion of the alkylene glycol monoalkyl ether can stably exert its effects with the maleic acid copolymer, a carbon number of 2 to 10 is preferable. Considering the ease with which the effects can be obtained, a carbon number of 3 to 8 is preferable, and more preferably 5 to 6 is preferable. Furthermore, regarding the number of carbon atoms in the alkyl ether portion of the alkylene glycol monoalkyl ether, a shorter alkyl ether portion is preferable, considering that it is easier to stably exert its effects with the maleic acid copolymer. For this reason, the number of carbon atoms is preferably between 1 and 6, and more preferably between 1 and 4, and even more preferably between 1 and 2, considering that it is easier to achieve stability and effects.

[0030] Furthermore, for alkylene glycol monoalkyl ethers, the solubility parameter (SP value) is 8-13 (cal / cm³). 3 ) 1 / 2This is preferable. This is because the effects of the present invention are more easily exhibited due to the compatibility with maleic acid copolymers. More specifically, the solubility parameter (SP value) should be 9-12 (cal / cm³). 3 ) 1 / 2 Preferably, the solubility parameter (SP value) is 10-11 (cal / cm³). 3 ) 1 / 2 It is preferable that this be the case. In this invention, the solvent solubility parameter (SP value) is a value expressed as the square root of the molecular cohesive energy, and is described in Chapter IV, Solubility Parameter Values, of the Polymer Handbook (Second Edition). The unit is (cal / cm³)¹ / ², and it refers to the value at 25°C. For data that is not provided, it can be calculated using the method described in RFFedors, Polymer Engineering Science, 14, p147 (1967).

[0031] Furthermore, it is preferable that the boiling point of the alkylene glycol monoalkyl ether be 170°C or higher. This is because if the boiling point is below 170°C, the alkylene glycol monoalkyl ether tends to evaporate easily, increasing the ink viscosity, making it difficult to suppress skipped lines and streaks in the writing, and thus affecting the writing feel. If given more consideration, it is preferable that the boiling point be 220°C or higher. On the other hand, if the boiling point exceeds 300°C, it tends to affect the drying properties of the writing, so it is preferable that the boiling point be 300°C or lower, and if given more consideration, it is preferable that the boiling point be 280°C or lower.

[0032] Furthermore, regarding the amide solvent, considering that it is easy to stably exert its effects with the maleic acid copolymer, it is preferable to use 3-methoxy-N,N-dimethylpropanamide or 3-butoxy-N,N-dimethylpropanamide, and more preferably 3-methoxy-N,N-dimethylpropanamide.

[0033] Furthermore, considering the need to improve solubility, line skipping, smudging, bleed-through, ink drying speed, and bleeding in the ink composition, the content of the organic solvent is preferably 10% by mass or more and 90% by mass or less, and preferably 25% by mass or more and 80% by mass or less, based on the total amount of the ink composition.

[0034] (Coloring agent) The coloring agent used in the oil-based ballpoint pen ink composition used in the present invention is not particularly limited and can be selected and used as appropriate, such as dyes or pigments. Dyes and pigments may also be used in combination.

[0035] Dyes used in oil-based ink compositions include oil-soluble dyes, acid dyes, basic dyes, and metal-containing dyes, as well as various salt-forming types of these dyes, such as salt-forming dyes of acid dyes and basic dyes, salt-forming dyes of organic acids and basic dyes, and salt-forming dyes of acid dyes and organic amines. Among these, salt-forming dyes are preferable when considering stability with the maleic acid copolymer. The dyes include: Varifast Black 1802, Varifast Black 1805, Varifast Black 1807, Varifast Violet 1701, Varifast Violet 1704, Varifast Violet 1705, Varifast Blue 1601, Varifast Blue 1605, Varifast Blue 1613, Varifast Blue 1621, Varifast Blue 1631, Varifast Red 1320, Varifast Red 1355, Varifast Red 1360, Varifast Yellow 1101, Varifast 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, BASE OF BASIC DYES MVB-3 (all manufactured by Orient Chemical Industries, Ltd.), Eisenspiron Black GMH-Special, Eisenspiron Violet Examples include 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, SPT Blue 111, SPT Blue GLSH-Special, SPT Red 533, SPT Orange 6, SBN Yellow 510, SBN Yellow 530, and SRC-BH (all manufactured by Hodogaya Chemical Co., Ltd.). Pigments include inorganic, organic, and processed pigments, but specifically include carbon black, aniline black, ultramarine, lead yellow, titanium dioxide, iron oxide, phthalocyanine-based, azo-based, quinacridone-based, diketopyrrolopyrrole-based, quinophthalone-based, surene-based, triphenylmethane-based, perinone-based, perylene-based, dioxazine-based, metallic pigments, pearl pigments, fluorescent pigments, and phosphorescent pigments. These dyes and pigments may be used individually or in combination of two or more types.

[0036] Furthermore, it is preferable to use pigments as colorants, because the pigment particles create physical obstructions in the gap between the ball and the inner wall of the tip of the ballpoint pen, thus suppressing ink leakage. In addition, pigments are preferred because they have excellent ink fastness, and especially excellent lightfastness. Furthermore, using pigments is preferable because, in the case of ballpoint pens, the pigment particles can easily fill the gap between the ball and the tip body, creating a bearing-like effect that suppresses metal-to-metal contact, improving lubrication, allowing the ball to rotate stably, suppressing ball skipping, reducing line skipping and smudging in the writing, suppressing wear on the ball seat, and improving writing quality. When using a maleic acid copolymer to improve lubricity, as in the present invention, using pigments is even more effective. Moreover, the synergistic effect of the bearing action between the lubricating layer provided by the surfactant (described later) and the pigment particles makes it easier to maintain lubrication, which is preferable.

[0037] Regarding the pigment, the average particle size is preferably between 1 nm and 500 nm. More preferably between 30 nm and 350 nm, and even more preferably between 50 nm and 300 nm. This is because setting the particle size within the above range improves the smoothness, suppressing skipped or streaky lines in the writing, reducing wear on the ball bearing, and improving the writing feel. Here, the average particle diameter can be determined by the laser diffraction method, specifically by the particle diameter (D50) at which the volume accumulation of the particle size distribution reaches 50%, measured using a laser diffraction particle size distribution analyzer (product name "MicrotracHRA9320-X100", Nikkiso Co., Ltd.) based on values ​​calibrated using standard samples and other measurement methods. Furthermore, since the aforementioned pigment exerts the above-mentioned effects in the dispersion state of the pigment in the oil-based ballpoint pen ink composition, it is preferable to determine the particle size in the dispersed state.

[0038] In terms of pigment type, it is preferable to use pigments from among carbon black, quinacridone-based, surene-based, and diketopyrrolopyrrole-based pigments. Furthermore, considering the need to suppress skipped lines and smudged strokes in the writing, and to suppress wear on the ball bearing, it is preferable to use carbon black or diketopyrrolopyrrole-based pigments.

[0039] The colorant content is preferably 5% by mass or more and 30% by mass or less, relative to the total amount of the ink composition. This is because if it is less than 5% by mass, it is difficult to suppress skipped or streaked lines in the writing, suppress wear of the ball bearing, and obtain dark writing. If it exceeds 30% by mass, it tends to affect solubility in the ink. Considering this further, 7% by mass or more and 25% by mass or less is preferable, and if considering this even further, 10% by mass or more and 20% by mass or less is preferable.

[0040] (Surfactants) In the present invention, it is preferable to use a surfactant. This is because it is preferable to use a surfactant because it has the effect of improving the writing performance when the writing tip (tip) dries out while left in the atmosphere. When a surfactant is used, the formed film tends to soften, and the writing performance can be improved. Furthermore, surfactants are preferable because they further improve the lubrication of the writing tip (between the ball and the ball seat on the tip body), suppress ball skipping, reduce skipped or streaky lines in the writing, suppress wear on the ball seat, and thus improve the writing feel.

[0041] Examples of surfactants include silicone-based surfactants, fluorine-based surfactants, phosphate ester-based surfactants, polyoxyalkylene alkyl ethers, fatty acids, and fatty acid esters. Among these, considering the above effects, it is preferable to select from phosphate ester surfactants, fatty acids, and fatty acid esters, and more preferably, if given further consideration, it is preferable to select from phosphate ester surfactants and fatty acids, with phosphate ester surfactants being preferred.

[0042] As phosphate ester surfactants, specifically, those having an alkoxyethyl group (C n H 2n+1 OCH2CH2O) or an alkoxy group (C m H 2m+1 O), phosphate esters, mono-phosphates of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, di-phosphates of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, tri-phosphates of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, alkyl phosphate esters, alkyl ether phosphate esters or their derivatives, etc. may be mentioned.

[0043] Regarding phosphate ester surfactants, specifically, phoslex series (manufactured by SC Organic Chemistry Co., Ltd.), JP series (manufactured by Johoku Chemical Industry Co., Ltd.), Plasurf series (manufactured by Daiichi Kogyo Co., Ltd.), Phosphanol series (manufactured by Toho Chemical Industry Co., Ltd.), NIKKOL series (manufactured by Nikko Chemicals Co., Ltd.), etc. can be mentioned.

[0044] Among phosphate ester surfactants, considering improving slipperiness more, suppressing line skipping and streaking in handwriting, suppressing wear of the ball seat, and improving writing performance and writing feel, it is preferably selected from phosphate esters having an alkoxyethyl group (C n H 2n+1 O-C2H4O) or an alkoxy group (C m H 2m+1 O), mono-phosphates of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, and di-phosphates of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers.

[0045] Furthermore, among phosphate ester surfactants, it is preferable to use a phosphate ester surfactant having an alkyl group, considering that improving lubricity further suppresses ball skipping, reduces line skipping and smudging in the writing, and improves initial writing performance and writing feel. In particular, it is preferable that the alkyl group has 8 to 18 carbon atoms, more preferably 10 to 18 carbon atoms, and even more preferably 12 to 18 carbon atoms. This is because if the alkyl group has too few carbon atoms, it tends to lack lubricity, and if it has too many carbon atoms, it tends to affect stability over time.

[0046] Furthermore, when using a phosphate ester surfactant, the acid value is preferably 150 mgKOH / g or less, more preferably 120 mgKOH / g or less, and even more preferably 100 mgKOH / g or less, in order to facilitate the improvement in lubricity by the phosphate ester surfactant. Moreover, considering stability and lubricity in the oil-based ballpoint pen ink composition, the acid value is preferably 30 mgKOH / g or more and 150 mgKOH / g or less, preferably 40 mgKOH / g or more and 120 mgKOH / g or less, and more preferably 40 mgKOH / g or more and 100 mgKOH / g or less. The acid value shall be expressed as the number of milligrams of potassium hydroxide required to neutralize the acidic components contained in 1 gram of the sample.

[0047] The surfactant content is more preferably 0.1% by mass or more and 5.0% by mass or less, relative to the total amount of the oil-based ballpoint pen ink composition. This is because if it is less than 0.1% by mass, it is difficult to further improve the slipperiness, thereby suppressing line skipping and smudging in the writing, and improving the initial writing performance and writing feel. If it exceeds 5.0% by mass, the ink tends to become unstable over time. Taking these factors into consideration, the surfactant content relative to the total amount of the oil-based ballpoint pen ink composition is preferably 0.3% by mass or more and 4.0% by mass or less, and if considering these factors even more, it is preferably 0.5% by mass or more and 3.0% by mass or less.

[0048] (Organic amines) In the present invention, it is preferable to use an organic amine. This is because including an organic amine in the oil-based ballpoint pen ink composition improves the suppression of ball bearing wear under high writing pressure (writing load of 300 to 500 gf). Furthermore, when using surfactants such as phosphate ester surfactants, organic amines are preferred because they can be neutralized to stabilize the ink, further improving the lubrication of the writing tip, suppressing ball skipping, making it easier to reduce skipped or streaky lines in the writing, and thus improving the writing feel and initial writing performance. Examples of organic amines include amines containing ethylene oxide such as oxyethylene alkylamines and polyoxyethylene alkylamines, alkylamines such as laurylamine and stearylamine, aliphatic amines such as distearylamine, dimethyl laurylamine, dimethyl stearylamine, and dimethyl octylamine, and alkanolamines such as diethanolamine and triethanolamine. Among these, amines containing ethylene oxide are preferred when considering the suppression of ball seat wear under high writing pressure (writing load of 300-500 gf). These may be used individually or in combination of two or more.

[0049] Furthermore, considering the stability with maleic acid copolymers, colorants, surfactants, and other components, as well as the suppression of ball seat wear under high writing pressure (writing load of 300-500 gf), the total amine value of the organic amine is preferably 300 (mgKOH / g) or less. More preferably, the total amine value is 200 (mgKOH / g) or less, and even more preferably 150 (mgKOH / g) or less. On the other hand, considering the above effects, the lower limit of the total amine value is preferably 30 (mgKOH / g) or more. The total amine value indicates the total amount of primary, secondary, and tertiary amines, and is expressed in milligrams of potassium hydroxide equivalent to the amount of hydrochloric acid required to neutralize 1 g of the sample.

[0050] The content of the organic amine is preferably 0.1% by mass or more and 10% by mass or less of the total amount of the ink composition, considering stability with the maleic acid copolymer, colorant, surfactant and other components, and suppression of wear of the ball seat under high writing pressure (writing load of 300 to 500 gf). Furthermore, considering neutralization with the aforementioned surfactant, it is preferably 0.5% by mass or more and 5% by mass or less.

[0051] (resin) Furthermore, it is preferable to use a resin other than maleic acid copolymer as an ink viscosity modifier. Examples of resins include polyvinyl butyral resin, ketone resin, polyacetal resin, polyvinyl alcohol resin, cellulose resin, terpene resin, alkyd resin, phenoxy resin, and polyvinyl acetate resin, but among these, it is preferable to include polyvinyl butyral resin or ketone resin. This is because it is easier to improve the ink leakage suppression effect. Furthermore, if considering the suppression of ball bearing wear and the suppression of skipped lines and smudged writing, it is preferable to use ketone resin, and if considering the improvement of writing feel, it is preferable to use polyvinyl butyral resin.

[0052] Furthermore, ketone resin is preferable because it suppresses wear on the ball seat, reduces skipped or smudged lines in the writing, and also has the effect of suppressing blotting. Furthermore, ketone resins are preferred because they improve the suppression of wear (wear resistance) of the ball seat. Among ketone resins, it is preferable to use ketone resins having a cyclic structure such as an aromatic ring skeleton (containing benzene rings such as phenyl groups, acetophenone groups, and naphthalene groups) or a cyclohexane skeleton (containing cyclohexane rings such as cyclohexane groups and cyclohexanone groups). This is because a cushioning effect is obtained by the ketone resin having a cyclic structure, which improves the suppression of wear (wear resistance) of the ball seat. More preferably, ketone resins with an aromatic ring skeleton are preferred because they have a larger number of double bond structures, making it easier to obtain a stronger cushioning effect.

[0053] If the resin content is less than 1% by mass relative to the total amount of ink composition, it is difficult to obtain the writing performance and ink leakage suppression described above, and if it exceeds 40% by mass, its solubility in the ink tends to be poor, so a content of 1% by mass or more and 40% by mass or less relative to the total amount of ink composition is preferred. Furthermore, considering this, 5% by mass or more is preferred, and if it exceeds 30% by mass, the ink viscosity tends to become too high, affecting the writing feel and initial writing performance, so a content of 5% by mass or more and 30% by mass or less is preferred.

[0054] In addition, other substances such as colorants, stabilizers, water, plasticizers, chelating agents, shear viscosity reducers, stringiness enhancers, and preservatives may be used as appropriate. These may be used individually or in combination of two or more.

[0055] Also, at 20°C and a shear rate of 200 sec. -1 While there are no particular limitations on ink viscosity (during writing), if you consider increasing ink consumption to suppress skipped or smudged lines in the writing, and to improve initial writing performance and writing feel, then 20°C and a shear rate of 200 sec is recommended. -1 The ink viscosity (during writing) is preferably 5000 mPa·s or less, more preferably 4000 mPa·s or less, and more preferably 3500 mPa·s or less. On the other hand, having an appropriate ink viscosity suppresses the acceleration of wear between the ball and the ball seat of the tip body, and considering writing performance such as bleed-through, smudging, bleeding, and drying of the ink, as well as pigment dispersion, the ink viscosity is preferably 500 mPa·s or more, and more preferably 800 mPa·s or more. Furthermore, this method is effective for retractable writing instruments such as click-type and twist-type writing instruments, where it is necessary to consider the initial writing performance and ink leakage prevention more carefully.

[0056] (Ballpoint pen) Furthermore, the ink consumption per 100m of a ballpoint pen is preferably between 20mg and 100mg. This is because an ink consumption within this range suppresses skipping and smudging in the handwriting, improves writing quality, and makes it easier to produce dark lines. More specifically, it is preferable that the ink consumption is between 25mg and 90mg, and preferably between 40mg and 80mg. Regarding ink consumption, a spiral writing test was conducted using five test samples at a writing speed of 4 m / min, under the conditions of 20°C, a writing angle of 70°, a writing load of 200 g, and on JIS P3201 writing paper. The average value of the ink consumption per 100 m was defined as the ink consumption per 100 m.

[0057] (Ballpoint pen tip) Regarding the ballpoint pen tip, it is preferable to maintain lubrication between the ball and the tip body, suppress skipping and smudging of the writing, and suppress wear of the ball seat to improve the writing feel, and to provide a ball seat with a roughly arc-shaped surface on the bottom wall of the ball-holding chamber.

[0058] Furthermore, the arithmetic mean roughness (Ra) of the ball surface of the ballpoint pen tip used in this invention is preferably 0.1 nm or more and 12 nm or less. This is because an arithmetic mean roughness (Ra) within the above range suppresses ball skipping, reduces skipped or faded lines in the writing, improves writing feel, and makes it easier to produce dark lines. More preferably, the arithmetic mean roughness (Ra) is 0.1 nm or more and 10 nm or less, and more preferably 1 nm or more and 8 nm or less. Surface roughness can be measured using a Seiko Epson SPI3800N.

[0059] Furthermore, while there are no particular limitations on the materials used for the balls, examples include cemented carbide balls with tungsten carbide as the main component, metal balls such as stainless steel, ceramic balls such as silicon carbide, silicon nitride, alumina, silica, and zirconia, and ruby ​​balls.

[0060] Furthermore, while ballpoint pen tips can be made from various materials such as stainless steel, nickel silver, brass, aluminum bronze, and aluminum, as well as resins like polycarbonate, polyacetal, and ABS, a stainless steel tip body is preferable considering wear on the ball seat and long-term stability.

[0061] Furthermore, it is preferable that the amount of movement of the ball in the ballpoint pen tip used in the present invention in the vertical axis direction is 3 μm or more and 25 μm or less. This is because, within the above range, ink consumption is increased, ball skipping is suppressed, line skipping and smudging in the writing are suppressed, the writing feel is improved, and it is easier to produce dark lines. More preferably, the amount of movement of the ball in the ballpoint pen tip in the vertical axis direction is 3 μm or more and 22 μm or less, 5 μm or more and 20 μm or less, and more preferably, 7 μm or more and 18 μm or less.

[0062] Example 1 The oil-based ballpoint pen ink composition of Example 1 was obtained by using the following ink components, weighing a predetermined amount of these components, heating them to 60°C, and then thoroughly stirring them using a disperser stirrer. The specific proportions of the ingredients are as follows.

[0063] Pigment dispersion (carbon black, average particle size 150 nm, 35% pigment content, 20% polyvinyl butyral content) 30.0% by mass Alcohol solvent (benzyl alcohol) 34.0% by mass Polyoxyalkylene glyceryl ether (Formula (1), polyoxypropylene diglyceryl ether) 20.0% by mass Maleic acid copolymer (styrene-maleic anhydride copolymer) 2.0% by mass Phosphate ester surfactant (alkyl group with 18 carbon atoms, acid value 85 (mgKOH / g)) 2.0% by mass Organic amine (polyoxyethylene alkylamine) 2.0% by mass Polyvinyl butyral resin 10.0% by mass

[0064] Testing and evaluation In Examples 1-22 and Comparative Examples 1-2, the oil-based ballpoint pen ink compositions (0.27 g) prepared were filled into an oil-based ballpoint pen refill, which was fitted with a ballpoint pen tip (with a ball diameter of φ0.7 mm rotatably held, a ball movement in the longitudinal axis direction of the ball of 15 μm, and an arithmetic mean roughness (Ra) of the ball surface of 6 nm) attached to an ink container (polypropylene), thereby producing an oil-based ballpoint pen.

[0065] Examples 2-22 As shown in Table 1, oil-based ballpoint pen ink compositions for Examples 2 to 22 were obtained using the same procedure as in Example 1, except that the ink components and tip specifications were changed. The measurement and evaluation results are shown in the table.

[0066] Comparative Examples 1-2 As shown in the table, oil-based ballpoint pen ink compositions for Comparative Examples 1 and 2 were obtained using the same procedure as in Example 1, except that the ink components and tip specifications were changed. The measurement and evaluation results are shown in the table. [Table 1] [Table 2] [Table 3]

[0067] Furthermore, the ink viscosity of Examples 1, 4, and 13 was measured using a Brookfield Viscometer RVDVII+Pro CP-52 spindle, under conditions of 20°C and a shear rate of 200 sec. -1 In Example 1, the ink viscosity was 3000 mPa·s; in Example 4, it was 3000 mPa·s; and in Example 13, it was 4300 mPa·s. Furthermore, when testing the ink consumption per 100m using an oil-based ballpoint pen in a spiral writing test, the results were: Example 1: 57mg / 100m, Example 4: 52mg / 100m, and Example 13: 53mg / 100m.

[0068] Writing performance test (line skipping and smudging in handwriting): The test involved writing characters by hand and observing the resulting handwriting. ◎...Handwriting with no or minimal skipped lines or smudging. ○...There are some skipped lines and slight smudging in the handwriting, but it is at a level that does not affect practical use. △···The handwriting has skipped lines and smudges, which affect its practical use. ×...Many skipped lines and smudged strokes in the handwriting.

[0069] Initial writing performance test: After writing by hand, the pen tip was left exposed in an environment of 20°C and 65% RH for 24 hours. Then, a running test was conducted under the following writing conditions, and the length of the initial ink smudging was measured. <Writing Conditions> The test was performed by writing in a straight line on a running test machine under the following conditions: writing load of 200gf, writing angle of 70°, and writing speed of 4m / min. ◎...Those with a brushstroke length of less than 5mm ○...The length of the smudged or faded writing is 5mm or more and less than 10mm. △···Those where the length of the fading or smudging is 10mm or more but less than 20mm. ×...The length of the smudged or faded writing is 20mm or longer.

[0070] Writing feel: This was evaluated by conducting a sensory test using handwritten notes on the test paper. ◎...very smooth ○...Smooth △···Somewhat less smooth ×...heavy things

[0071] Abrasion resistance test (ball seat abrasion test): The abrasion of the ball seat after the writing test was measured using a running test machine with a load of 400gf, a writing angle of 70°, and a speed of 4m / min. ◎...Ball seat wear is less than 5μm ○...Ball seat wear of 5 μm or more and less than 10 μm △···The ball bearing wear is between 10 μm and 20 μm, but it is still writable. ×...The ball bearing is severely worn, resulting in poor writing performance.

[0072] In Examples 1 to 22, good performance was obtained in all tests, including writing performance (no skipping or smudging of lines in the writing), initial writing performance, writing feel, and abrasion resistance (abrasion test of the ball bearing).

[0073] In Comparative Examples 1 and 2, the writing performance test (line skipping and smudging in the handwriting) was inferior because maleic acid copolymer was not used.

[0074] Furthermore, when using retractable oil-based ballpoint pens (retractable ballpoint pens) such as retractable or twist-action oil-based ballpoint pens, the initial writing performance is one of the important performance characteristics, so using an oil-based ballpoint pen ink composition like the present invention is effective.

[0075] Furthermore, in this embodiment, for convenience, an oil-based ballpoint pen is illustrated in which an oil-based ballpoint pen refill containing an oil-based ballpoint pen ink composition is directly contained within the barrel. However, the oil-based ballpoint pen of the present invention may also be a direct-fill type oil-based ballpoint pen in which the barrel serves as an ink storage cylinder and the oil-based ballpoint pen ink composition is directly contained within the barrel. Also, in this embodiment, for convenience, a ballpoint pen tip formed by cutting wire is illustrated in example, but a ballpoint pen tip formed by pressing pipe material may also be used. Furthermore, the oil-based ballpoint pen ink composition of the present invention may be used not only in oil-based ballpoint pens, but also in oil-based markers, oil-based felt-tip pens, and the like. [Industrial applicability]

[0076] The present invention can be used as an oil-based ballpoint pen, and more specifically, it can be widely used as an oil-based ballpoint pen with a cap, retractable tip, etc.

Claims

1. An oil-based ballpoint pen ink composition comprising a colorant, an organic solvent, and a maleic acid copolymer, wherein the maleic acid copolymer is a styrene-maleic anhydride copolymer or an olefin-maleic acid copolymer.

2. The oil-based ballpoint pen ink composition according to claim 1, characterized in that the content of the maleic acid copolymer is 0.1 to 5% by mass with respect to the total amount of the ink composition.

3. The oil-based ballpoint pen ink composition according to claim 1 or 2, characterized in that the organic solvent is selected from an alkylene oxide derivative of glycerin, an alkylene glycol alkyl ether solvent, an amide solvent, and an aromatic alcohol.

4. The oil-based ballpoint pen ink composition according to claim 1 or 2, characterized in that the oil-based ballpoint pen ink composition contains an organic amine.

5. The oil-based ballpoint pen ink composition according to claim 1 or 2, characterized in that the oil-based ballpoint pen ink composition contains a surfactant.

6. An oil-based ballpoint pen characterized by containing the oil-based ballpoint pen ink composition described in claim 1 or 2.

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