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

Abstract

To provide an ink composition for an oily ball point pen which improves writing adhesion to a paper surface and slipperiness, does not cause line skipping and writing blurring in handwriting, has good writing property, and improves writing feeling and wear suppression of a ball seat under high writing pressure (writing load of 300 to 500 gf), and an oily ball point pen using the same.SOLUTION: An ink composition for an oily ball point pen contains a coloring agent, a terpene phenol resin, and an alkylene oxide derivative of glycerol.SELECTED DRAWING: None

Description

[Technical Field]

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

[0002] Oil-based ballpoint pens are susceptible to writing resistance between the ball and the tip body during writing, which affects the writing feel. In particular, unlike other types of writing instruments, ballpoint pens have a ballpoint pen tip consisting of a metal tip made of stainless steel or the like at the end, 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. However, the rotation of the ball during writing can cause line skipping, streaking, uneven dots, poor writing feel, and ink buildup at the tip, resulting in blobs.

[0003] To solve these problems, numerous oil-based ballpoint pen ink compositions have been proposed that use various lubricants to improve lubrication and suppress writing resistance between the ball and the tip body.

[0004] Examples of oil-based ballpoint pen ink compositions using such additives include those using alkyl β-D-glucoside, as disclosed in Japanese Patent Publication No. 5-331403 "Oil-based ballpoint pen ink"; those using polyethylene glycol with an average molecular weight of 200 to 4,000,000, as disclosed in Japanese Patent Publication No. 7-196971 "Oil-based ballpoint pen ink composition"; those using N-acyl amino acids, N-acylmethyltauric acid, and N-acylmethylalanine, as disclosed in Japanese Patent Publication No. 2007-176995 "Oil-based ballpoint pen ink"; and those containing at least deca-macadamia nut oil fatty acid decaglyceryl and polyoxyethylene alkyl ether with 16 or more carbon atoms in the alkyl group and solid at room temperature, as disclosed in Japanese Patent Publication No. 2008-88264 "Oil-based ballpoint pen ink composition," etc. (Patent Documents 1-4) [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] "Unexamined Japanese Patent Publication No. 5-331403" [Patent Document 2] "Unexamined Japanese Patent Publication No. 7-196971" [Patent Document 3] "Japanese Patent Publication No. 2007-176995" [Patent Document 4] "Japanese Patent Publication No. 2008-88264" [Overview of the project] [Problems that the invention aims to solve]

[0006] However, while using various additives such as those described in Patent Documents 1-4 can reduce the writing resistance between the ball and the tip to some extent, it does not result in a satisfactory writing feel, and furthermore, it does not improve writing quality such as skipped lines or streaking, leaving room for improvement.

[0007] The object of the present invention is to provide an oil-based ballpoint pen ink composition and an oil-based ballpoint pen using the same, which can improve writing feel, suppression of ball bearing wear under high writing pressure (writing load of 300-500 gf), and provide smooth writing without skipping or smudging of lines. [Means for solving the problem]

[0008] To solve the above problems, the present invention 1. An oil-based ballpoint pen ink composition characterized by comprising a colorant, a terpene phenol resin, and an alkylene oxide derivative of glycerin. 2. The oil-based ballpoint pen ink composition according to paragraph 1, characterized in that the weight-average molecular weight of the terpene phenol resin is 200 or more and 1200 or less. 3. The oil-based ballpoint pen ink composition according to paragraph 1 or 2, characterized in that the weight-average molecular weight of the alkylene oxide derivative of glycerin is 300 or more and 5,000 or less. 4. The alkylene oxide average addition mole number of the alkylene oxide derivative of glycerin is 1 or more and 30 or less, and the ink composition for an oil-based ballpoint pen according to any one of claims 1 to 3, characterized in that. 5. The ink composition for an oil-based ballpoint pen according to any one of claims 1 to 4, characterized in that the ink composition for an oil-based ballpoint pen contains at least one selected from a phosphate ester surfactant, a silicone surfactant, a surfactant having an acetylene bond, a fluorine-based surfactant, a fatty acid, and a fatty acid ester. 6. The ink composition for an oil-based ballpoint pen according to any one of claims 1 to 5, characterized in that the ink composition for an oil-based ballpoint pen contains a rosin resin. 7. An oil-based ballpoint pen having a ballpoint pen tip that rotatably holds a ball at the tip of an ink containing cylinder, and containing the ink composition for an oil-based ballpoint pen according to any one of claims 1 to 6 in the ink containing cylinder.

Effects of the Invention

[0009] The present invention has improved adhesion and slipperiness of the handwriting to the paper surface, so that there are no streaks or smudges in the handwriting, the writing property is good, and the wear resistance of the ball seat under high writing pressure (writing load 300 to 500 gf) is improved. An ink composition for an oil-based ballpoint pen and an oil-based ballpoint pen using the same could be obtained.

Modes for Carrying Out the Invention

[0010] Hereinafter, embodiments of the present invention will be described in detail. In this specification, "parts", "%", "ratio", etc. indicating the formulation are based on mass unless otherwise specified, and the content is the mass% of the constituent components based on the mass of the ink composition for an oil-based ballpoint pen.

[0011] The feature of the present invention is that the ink composition for an oil-based ballpoint pen contains a colorant, a terpene phenol resin, and an alkylene oxide derivative of glycerin.

[0012] It has been found that by including terpene phenol resin and an alkylene oxide derivative of glycerin in an oil-based ballpoint pen ink composition, it is possible to improve the adhesion and smoothness of the writing on the paper surface, resulting in smooth writing without skipping or smudging, and further improving the writing feel and suppressing wear of the ball seat under high writing pressure (writing load of 300-500 gf).

[0013] (Terpene phenol resin) As the terpene phenol resin used in the present invention, for example, a resin produced by polymerizing terpenes such as α-pinene, β-pinene, limonene, and terpinolene in a reaction system containing phenols can be used. Examples of phenols include phenol, bisphenol A, or alkylphenols such as cresol, xylenol, pt-butylphenol, p-octylphenol, and p-nonylphenol.

[0014] Regarding terpene phenol resin, by forming a strong writing film, it improves the adhesion of the writing to the paper surface, resulting in good writing quality, free from skipped or smudged lines, and excellent writing performance. Furthermore, the aromatic ring skeleton of terpene phenol resin provides a cushioning effect between the ball and the ball seat, improving lubricity and suppressing resistance between the ball and the ball seat, thereby improving writing feel and suppressing wear of the ball seat under high writing pressure (writing load of 300-500 gf). By using the alkylene oxide derivative of glycerin described later in combination, an interaction occurs that further improves lubricity, improving writing feel and suppressing wear of the ball seat under high writing pressure (writing load of 300-500 gf).

[0015] Regarding the weight-average molecular weight of the terpene phenol resin, considering that a stronger writing film is formed, thereby improving the adhesion of the writing to the paper surface (writing performance), preventing skipped or faded lines in the writing, resulting in good writing performance, easier improvement of smoothness, and better dissolution stability in ink, making it easier to obtain the effects of the present invention, a weight-average molecular weight of 200 to 1200 is preferable. Furthermore, considering better adhesion of the writing to the paper surface, suppression of skipped or faded lines in the writing, and dissolution stability in ink, a weight-average molecular weight of 300 to 1000 is preferable, and 400 to 800 is preferable. Moreover, if the weight-average molecular weight is too high, it tends to affect stability over time, and furthermore, the viscosity of the oil-based ballpoint pen ink composition tends to increase, which tends to affect the writing due to ink followability, and the writing tends to be prone to skipped or faded lines. The weight-average molecular weight of the terpene phenol resin is measured by GPC (gel permeation chromatography).

[0016] Regarding the softening point of the terpene phenol resin, it is preferable that it be between 70°C and 150°C, considering that maintaining viscoelasticity allows for the formation of a stronger writing film, thereby improving the adhesion of the writing to the paper surface (writing performance), preventing skipped or smudged lines in the writing, resulting in good writing performance, easier improvement of slipperiness, and better dissolution stability in ink, thereby making it easier to obtain the effects of the present invention. The above softening point is preferable to be between 80°C and 130°C, considering that maintaining viscoelasticity further improves the adhesion of the writing to the paper surface and suppresses skipped or smudged lines in the writing, and more preferably between 90°C and 110°C. Here, the softening point of the resin is a value measured in accordance with JIS K2207.

[0017] For terpene phenol resins, the hydroxyl value is generally controlled by the amount of phenol moiety. Considering the need to improve the adhesion of handwriting to the paper surface (writing performance), eliminate skipped or smudged lines, improve writing performance, enhance slipperiness, and improve solubility in ink, thereby making it easier to obtain the effects of the present invention, a hydroxyl value of 200 mgKOH / g or less is preferable for the terpene phenol resin. More specifically, the above hydroxyl value is preferably 30 mgKOH / g to 200 mgKOH / g, preferably 50 mgKOH / g to 200 mgKOH / g, preferably 50 mgKOH / g to 200 mgKOH / g, and preferably 50 mgKOH / g to 100 mgKOH / g. The hydroxyl value is defined as the number of milligrams of potassium hydroxide required to neutralize the acetic acid bonded to the hydroxyl groups when acetylating 1 g of resin, and is measured based on the potentiometric titration method specified in JIS K 0070.

[0018] If the terpene phenol resin content is less than 0.1% by mass relative to the total amount of the oil-based ballpoint pen ink composition, it is difficult to obtain sufficient effects for adhesion of the writing to the paper surface and for smoothness. On the other hand, if the resin content relative to the total amount of the oil-based ballpoint pen ink composition exceeds 20% by mass, the solubility in the ink tends to be poor, the ink viscosity becomes too high, and this tends to affect the ink consumption, writing feel, and initial writing performance. For this reason, the resin content relative to the total amount of the oil-based ballpoint pen ink composition is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 1% by mass or more and 10% by mass or less.

[0019] (A glycerin alkylene oxide derivative) In this invention, the alkylene oxide derivative of glycerin is used to improve lubricity, thereby maintaining lubrication between the writing tip and the writing surface (lubrication 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), improving writing feel, and resulting in smoother writing with fewer skipped or streaked lines. As in this invention, by using it in combination with a terpene phenol resin, the interaction works to further improve the adhesion of the writing to the paper surface and enhance lubricity, thereby suppressing wear of the ball seat, improving writing feel, and resulting in smoother writing with fewer skipped or streaked lines. Furthermore, because alkylene oxide derivatives of glycerin generally have low volatility, even when the writing tip is left in the atmosphere, they improve the initial writing performance of the writing tip and also improve ink followability by minimizing ink viscosity in the oil-based ballpoint pen ink composition. In particular, terpene phenol resins tend to form a strong ink film at the writing tip and have a significant impact on the initial writing performance of the writing tip, so they can be used effectively. Moreover, since alkylene oxide derivatives of glycerin themselves also exhibit viscosity, it is possible to reduce the amount of terpene phenol resin when adjusting the ink viscosity, which also makes the ink film less likely to become strong and improves the initial writing performance of the writing tip. Therefore, it is preferable to use them in combination with terpene phenol resins. Examples of alkylene oxide derivatives of glycerin include polyoxyalkylene glyceryl ether, polyoxyalkylene alkyl glucoside, and polyoxypropylene alkyl ether. However, considering the need to further improve lubricity, thereby suppressing wear of the ball bearing and improving writing feel and preventing skipping or smudging of lines in the handwriting, polyoxyalkylene glyceryl ether is preferred.

[0020] 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.

[0021] Furthermore, when using pigments as in the present invention, 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, thereby improving ink followability and resulting in good handwriting. For this reason, considering pigment dispersion stability and ink followability, it is preferable to use polyoxyalkylene glyceryl ether, and among these, polyoxyalkylene diglyceryl ether is preferable if given even greater consideration.

[0022] 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.

[0023] Considering that polyoxyalkylene glyceryl ether improves lubricity, thereby suppressing wear of the ball seat, improving writing feel and preventing skipping and smudging of lines in the handwriting, 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 50 or less. More preferably, the average number of added moles of alkylene oxide is 1 or more and 30 or less. Considering further improvement in lubricity 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.

[0024] In particular, considering the need to further improve lubricity to suppress wear of the ball seat and to improve writing feel and reduce skipping and smudging of lines in the handwriting, the average number of moles of propylene oxide added is preferably 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 the ease with which the effects of the present invention are 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.

[0025] 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.

[0026] 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 tends to affect the handwriting due to ink-following properties. If stability over time and ink-following properties are taken into consideration, the weight-average molecular weight is preferably 3000 or less, more preferably 1500 or less, and more preferably 1200 or less. If further consideration is given to improving slipperiness and producing 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 the weight-average molecular weight is preferably 300 or more, and if further consideration is given, 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.

[0027] Furthermore, if the content of the alkylene oxide derivative of glycerin is less than 0.1% by mass relative to the total amount of the oil-based ballpoint pen ink composition, the effects of lubricity and ink-following properties may not be obtained, and if it exceeds 40% by mass, it may affect the stability over time. Therefore, it is preferable that the content be between 0.1% by mass and 40% by mass, and more preferably between 3% by mass and 30% by mass, relative to the total amount of the oil-based ballpoint pen ink composition. Moreover, considering the balance between suppression of ball seat wear and stability over time, it is preferable that the content be between 5% by mass and 25% by mass, and most preferably between 8% by mass and 25% by mass.

[0028] (Coloring agent) The coloring agent used in this 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. Examples of dyes 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. These dyes may be used individually or in combination of two or more types. As dyes, it is preferable to use salt-forming dyes considering the stability over time due to the compatibility of glycerin with alkylene oxide derivatives, and further, considering that stability over time can be maintained by the stability of the salt-forming bond, it is preferable to use salt-forming dyes of basic dyes and organic acids, salt-forming dyes of acid dyes and basic dyes, and salt-forming dyes of acid dyes and organic amines.

[0029] Regarding the dyes, specifically, these 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 Industry Co., 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 Violet 510, SBN Yellow 530, and SRC-BH (all manufactured by Hodogaya Chemical Co., Ltd.).

[0030] Pigments include inorganic, organic, and processed pigments, but specifically include carbon black, aniline black, ultramarine, lead yellow, titanium dioxide, iron oxide, phthalocyanine, azo, quinacridone, diketopyrrolopyrrole, quinophthalone, surene, triphenylmethane, perinone, perylene, dioxazine, metallic pigments, pearl pigments, fluorescent pigments, and phosphorescent pigments.

[0031] As a coloring agent, it is preferable to use pigments. This is because, in the case of ballpoint pens, pigment particles can easily fill the gap between the ball and the tip body, creating a bearing-like effect that suppresses metal contact and improves lubrication. This reduces wear on the ball seat and improves writing quality, resulting in smoother writing with fewer skipped or skipped lines. Furthermore, pigments are preferable because they have excellent water and light resistance, making them suitable for use in official documents. Furthermore, since the oil-based ballpoint pen ink composition can withstand high-pressure writing, it can be suitably used on carbonless paper and other similar materials, and is therefore preferable for use in official documents.

[0032] 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. By setting the particle size within this range, the lubricity is further improved, which suppresses wear on the ball bearing and improves the writing feel, resulting in a smoother writing experience with fewer skipped or streaked lines. 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 effects are achieved by 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.

[0033] Furthermore, it is preferable that the pigment content relative to the colorant content in the oil-based ballpoint pen ink composition be high. Specifically, by setting the pigment content relative to the colorant content to 10% by mass or more, water resistance, lightfastness, and slipperiness can be improved to the required level. However, in order to further reduce the likelihood of changes in handwriting in terms of water resistance, lightfastness, and slipperiness, it is preferable to set it to 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass, and particularly preferably 100% by mass.

[0034] Generally, oil-based ballpoint pen ink compositions containing pigments tend to have insufficient initial writing performance and ink-following ability when the writing tip dries. However, the oil-based ballpoint pen ink composition according to the present invention contains polyoxyalkylene glyceryl ether, which maintains good initial writing performance and ink-following ability even at high pigment content levels, resulting in good handwriting.

[0035] The colorant content is preferably 5 to 30% by mass of the total amount of the oil-based ballpoint pen ink composition. This is because if it is less than 5% by mass, it tends not to produce a dark writing line, and if it exceeds 30% by mass, it tends to affect the stability in the ink. Considering this tendency more carefully, 7 to 25% by mass is preferred, and if further considered, 10 to 20% by mass is preferable.

[0036] (Organic solvents) In the present invention, it is preferable that the product contains an organic solvent. Specifically, examples of organic solvents include glycol ether solvents such as 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-methoxybutanol, and 3-methoxy-3-methylbutanol; glycol solvents such as diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, and ethylene glycol; 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.

[0037] Among these organic solvents, aromatic alcohols are preferred because they improve lubricity due to the presence of aromatic rings, and they also have high compatibility with polyoxyalkylene glyceryl ethers, thus improving the stability of the solution.

[0038] (Surfactants) The oil-based ballpoint pen ink composition of the present invention preferably contains a surfactant. By including a surfactant in the oil-based ballpoint pen ink composition, it is possible to improve the lubricity and the initial writing performance and writing feel when the tip of the pen tip dries out after being left in the air.

[0039] The surfactant is preferably at least one selected from phosphate ester surfactants, silicone surfactants, surfactants having an acetylene bond, fluorine-based surfactants, fatty acids, and fatty acid esters.

[0040] Among surfactants, phosphate ester surfactants and silicone surfactants are preferable when considering the improvement of lubricity, resulting in good handwriting, as well as improved initial writing performance and writing feel. Furthermore, phosphate ester surfactants are preferred because they provide a more pronounced effect in improving lubricity.

[0041] Phosphate ester surfactants specifically include those containing an alkoxyethyl group (C n H 2n+1 OCH2CH2O) or alkoxy group (C m H 2m+1 Examples include phosphate esters containing O), monophosphate esters of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers, diphosphate esters of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers, triesters of polyoxyethylene alkyl ethers or polyoxyethylene alkylaryl ethers, alkyl phosphate esters, alkyl ether phosphate esters, or derivatives thereof.

[0042] Examples of phosphate ester-based surfactants include the phoslex series (manufactured by SC Organic Chemicals Co., Ltd.), the JP series (manufactured by Johoku Chemical Industry Co., Ltd.), the Plasurf series (manufactured by Daiichi Kogyo Co., Ltd.), the Phosphanol series (manufactured by Toho Chemical Industry Co., Ltd.), and the NIKKOL series (manufactured by Nikko Chemicals Co., Ltd.).

[0043] Among phosphate ester surfactants, if you want to further improve lubricity, produce good handwriting, and enhance initial writing performance and writing feel, consider using an alkoxyethyl group (C n H 2n+1 O-C2H4O) or alkoxy group (C m H 2m+1It is preferably selected from phosphoric esters having (O), mono-phosphoric esters of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers, and di-phosphoric esters of polyoxyethylene alkyl ethers or polyoxyethylene alkyl aryl ethers.

[0044] Furthermore, among phosphoric ester surfactants, considering the suppression of wear of the ball seat and the improvement of writing feel and the elimination of skipping and streaking in handwriting by further improving the slipperiness, it is preferable to use a phosphoric ester surfactant having an alkoxyethyl group (C n H 2n+1 O-C2H4O) or an alkoxy group (C m H 2m+1 O). More preferably, a phosphoric ester surfactant having an alkoxyl group (C m H 2m+1 O) is used.

[0045] Regarding the phosphoric ester surfactant, for the carbon chain (n, m) of the terminal alkyl group of the alkoxyethyl group (C n H 2n+1 O-C2H4O) or the alkoxy group (C m H 2m+1 O), it is preferably 1 or more and 20 or less. Furthermore, when the carbon chain (n, m) of the terminal alkyl group of the alkoxyethyl group (C n H 2n+1 O-C2H4O) or the alkoxy group (C m H 2m+1 O) has an appropriate length, it is easier to maintain better slipperiness. Therefore, the carbon chain (n, m) of the terminal alkyl group is preferably 1 or more and 20 or less. More preferably, the carbon chain (n, m) is preferably 1 or more and 12 or less, and the carbon chain (n, m) is preferably 2 or more and 12 or less, 3 or more and 8 or less, 3 or more and 6 or less.

[0046] Furthermore, among phosphate ester surfactants, it is preferable to use a phosphate ester surfactant having an alkyl group, considering that by further improving lubricity, it is preferable to suppress wear of the ball seat, improve writing feel and handwriting with no skipping or smudging, and improve 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. The above-mentioned alkoxyethyl group (C n H 2n+1 O-C2H4O) or alkoxy group (C m H 2m+1 The interaction of a phosphate ester surfactant having O) and a phosphate ester surfactant having an alkyl group makes it easier to improve lubricity, thus making it effective and preferable to obtain the effects of the present invention.

[0047] Furthermore, when using a phosphate ester surfactant, the acid value is preferably 160 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 160 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 above-mentioned alkoxyethyl group (C n H 2n+1 O-C2H4O) or alkoxy group (C m H 2m+1 The interaction of a phosphate ester surfactant having O) and a phosphate ester surfactant having a specific acid value makes it easier to improve lubricity, thus making it effective and preferable to obtain the effects of the present invention. 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.

[0048] 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 tends to be difficult to achieve the desired improved lubricity, suppression of ball seat wear, good writing feel, and smooth writing with no skipping or smudging, as well as poor initial writing performance. If it exceeds 5.0% by mass, the ink tends to become unstable over time. Considering these factors, 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 more preferably 0.5% by mass or more and 3.0% by mass or less.

[0049] When the oil-based ballpoint pen ink composition according to the present invention contains a surfactant, the blending ratio (glycerin alkylene oxide derivative / surfactant) of the surfactant, particularly the glycerin alkylene oxide derivative as described above, is preferably 1 to 30 times by mass, more preferably 1 to 25 times, more preferably 1 to 20 times, more preferably 1 to 15 times, more preferably 2 to 15 times, preferably 3 to 15 times, and most preferably 5 to 15 times. Within this range, it is possible to improve the smoothness, writing feel, and ink aging in a well-balanced manner.

[0050] (Organic amines) The oil-based ballpoint pen ink composition according to the present invention preferably contains an organic amine in order to improve the stability of the components contained in the ink composition. Examples include amines having ethylene oxide, such as oxyethylene alkylamine and polyoxyethylene alkylamine; alkylamines, such as laurylamine and stearylamine; and aliphatic amines, such as distearylamine, dimethyl laurylamine, dimethyl stearylamine, and dimethyl octylamine. Among these, amines having ethylene oxide and dimethyl alkylamines are preferred. Furthermore, amines having ethylene oxide are preferred when considering good lubricity and long-term stability, and when considering how to easily obtain the effects of the present invention.

[0051] Furthermore, the total amine value of the organic amine is preferably between 100 mgKOH / g and 300 mgKOH / g, considering its stability with the surfactant, pigment, and other components. This is because if it exceeds 300 mgKOH / g, the reactivity is too strong, making it prone to reacting with the above components, which tends to result in poor stability over time. Also, if the total amine value is less than 100 mgKOH / g, the stability of the surfactant in the oil-based ballpoint pen ink composition tends to decrease, and the lubricity tends to decrease. From the viewpoint of stability with the above components and lubricity, it is more preferable that the total amine value be in the range of 150 mgKOH / g and 300 mgKOH / g. Furthermore, from the viewpoint of stability, it is preferable that it be between 180 mgKOH / g and 300 mgKOH / g, and more preferably between 230 mgKOH / g and 270 mgKOH / g. In this invention, the total amine value represents 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.

[0052] Furthermore, regarding the reactivity of organic amines with other components in the oil-based ballpoint pen ink composition, primary amines exhibit the strongest reactivity, followed by secondary amines and then tertiary amines, which have decreasing reactivity. Therefore, considering stability over time, it is preferable to use secondary or tertiary amines. These may be used individually or in combination of two or more.

[0053] Furthermore, to adjust the ink viscosity and improve the adhesion of the writing to the paper surface, resulting in good writing quality without skipped or smudged lines, and to ensure good writing performance, it is preferable that the ink contains a rosin-based resin. Examples of rosin-based resins include rosin, rosin ester, and hydrogenated rosin ester, but considering the need for even less skipped or smudged lines and better writing performance, it is preferable to use rosin ester or hydrogenated rosin ester. Moreover, since it is possible to reduce the content of terpene phenol resin, the ink film is less likely to become rigid, making it easier to improve the initial writing performance at the tip of the pen, so it is preferable to use it in combination with terpene phenol resin.

[0054] Regarding the softening point of rosin-based resins, considering the need to improve the adhesion of handwriting to the paper surface (writing performance), resulting in smoother writing without skipped or smudged lines, a softening point of 50°C to 150°C is preferable. More preferably, a softening point of 60°C to 130°C is preferable, and a softening point of 65°C to 115°C is preferable. Here, the softening point of the resin is a value measured in accordance with JIS K2207.

[0055] If the rosin-based resin content is less than 0.1% by mass relative to the total amount of the oil-based ballpoint pen ink composition, it is difficult to obtain sufficient effect in terms of ink adhesion (writing performance) to the paper surface. Furthermore, if the resin content exceeds 20% by mass relative to the total amount of the oil-based ballpoint pen ink composition, the solubility in the ink tends to be poor, the ink viscosity becomes too high, and this tends to affect the ink consumption, writing feel, and initial writing performance. For this reason, the total resin content relative to the total amount of the oil-based ballpoint pen ink composition is preferably between 0.1% by mass and 20% by mass, and more preferably between 1% by mass and 15% by mass, and more preferably between 5% by mass and 12% by mass.

[0056] (resin) The oil-based ballpoint pen ink composition of the present invention preferably contains other resins besides terpene phenol resins and rosin-based resins in order to improve the adhesion of the writing to the paper surface and suppress ink leakage at the writing tip. Examples of other resins include polyvinyl butyral resin, ketone resin, amide resin, rosin resin, terpene phenol resin, alkylphenol resin, polyvinyl butyral resin, styrene-maleic acid resin, ethylene-maleic acid resin, styrene-acrylic resin, acrylic resin, maleic acid resin, cellulose resin, petroleum resin, coumarone-indene resin, polyethylene oxide, polymethacrylate ester, ketone-formaldehyde resin, and α- and β-pinene-phenol polycondensation resins. These may be used individually or in combination of two or more.

[0057] Among these resins, if the goal is to further improve the adhesion of the writing to the paper surface (writing performance), eliminate skipped or smudged lines, and ensure good writing performance, while also considering smoothness and suppressing ink leakage at the writing tip, then at least one of polyvinyl butyral resin and ketone resin is preferable as the resin included in the oil-based ballpoint pen ink composition. If further consideration is given to smoothness and suppressing ink leakage at the writing tip, then polyvinyl butyral resin is even more preferable.

[0058] Furthermore, regarding the average degree of polymerization of polyvinyl butyral resin, in order to further improve the adhesion of handwriting to the paper surface (writing performance), to ensure that there are no skipped or smudged lines in the handwriting, and to consider the smoothness and suppression of ink leakage at the tip of the pen, an average degree of polymerization of 100 to 2,000 is preferable, and if further consideration is given, an average degree of polymerization of 100 to 1,500 is preferable, and 200 to 1,000 is more preferable. Here, the average degree of polymerization refers to the number of basic units that make up one molecule of polyvinyl butyral resin, and a value measured based on the method specified in JIS K6728 (2001 edition) can be adopted.

[0059] Furthermore, it is preferable that the polyvinyl butyral resin has a hydroxyl group content of 25 mol% or more. This is because polyvinyl butyral resins with a hydroxyl group content of less than 25 mol% do not have sufficient solubility in alkylene glycol alkyl ether solvents, making it difficult to obtain the effects of the present invention. Considering this further, polyvinyl butyral resins with a hydroxyl group content of 30 mol% or more are preferable, as they are more likely to improve slipperiness and writing feel. Also, if polyvinyl butyral resins with a hydroxyl group content exceeding 40 mol% are used, the amount of moisture absorbed tends to increase, which can easily affect the stability over time with the ink components. Therefore, polyvinyl butyral resins with a hydroxyl group content of 40 mol% or less are preferable. For this reason, polyvinyl butyral resins with a hydroxyl group content of 30 mol% to 40 mol% are preferable, and more preferably, those with a hydroxyl group content of 30 mol% to 36 mol% are preferable. The hydroxyl group content (mol%) of the polyvinyl butyral resin refers to the percentage of hydroxyl groups (mol%) relative to the total mole amounts of butyral groups (mol%), acetyl groups (mol%), and hydroxyl groups (mol%).

[0060] If the resin content is less than 3% by mass relative to the total amount of the oil-based ballpoint pen ink composition, it is difficult to obtain sufficient effects in terms of ink adhesion to the paper surface, smoothness, and ink leakage suppression. Furthermore, if the total resin content relative to the total amount of the oil-based ballpoint pen ink composition exceeds 40% by mass, the solubility in the ink tends to be poor, the ink viscosity becomes too high, and this tends to affect the ink consumption, writing feel, and initial writing performance. For this reason, the total resin content relative to the total amount of the oil-based ballpoint pen ink composition is preferably 3% by mass or more and 40% by mass or less, and more preferably 5% by mass or more and 30% by mass or less, and 10% by mass or more and 25% by mass or less.

[0061] Furthermore, the oil-based ballpoint pen ink composition of the present invention may also contain, as appropriate, dyes, colorant stabilizers, plasticizers, chelating agents, defoaming agents, water, pseudoplasticity-imparting agents, etc. These may be used individually or in combination of two or more.

[0062] The viscosity of the oil-based ballpoint pen ink composition of the present invention is not particularly limited, but is measured at 20°C and a shear rate of 5 sec. -1 When the ink viscosity exceeds 15,000 mPa·s, the ball rotation resistance during writing increases, making the writing feel heavier. Furthermore, it can easily affect the initial writing performance and ink-following performance. To achieve good handwriting, the following conditions apply: 20°C, shear rate 5 sec -1 The ink viscosity is preferably 15,000 mPa·s or less. To further improve writing performance and ink-following performance and produce good handwriting, it is preferable to have a viscosity of 10,000 mPa·s or less, and more preferably 8,000 mPa·s or less, and even more preferably 6,000 mPa·s or less. Also, at 20°C and a shear rate of 5 sec. -1 When the ink viscosity is less than 10 mPa·s, the writing is more prone to bleeding and ink leakage, so at 20°C and a shear rate of 5 sec -1 Preferably, the ink viscosity is 10 mPa·s or higher, and more preferably, 100 mPa·s or higher, and even more preferably 5 mPa·s or higher.

[0063] (Oil-based ballpoint pen) Furthermore, the ink consumption per 100m of an oil-based ballpoint pen is preferably between 20mg and 100mg. This is because within this range, the writing is dark, free from skipped or smudged lines, and offers good writing performance and a pleasant writing feel. More specifically, it is preferable that the ink consumption is between 20mg and 80mg, or between 30mg and 70mg. 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.

[0064] Furthermore, the arithmetic mean roughness (Ra) of the ball surface of the oil-based ballpoint pen tip used in this invention is preferably 0.1 nm to 12 nm. This is because sufficient ink adheres to the ball surface, resulting in smooth writing without skipping or smudging, good writing performance, and good suppression of ball seat wear under high writing pressure (writing load of 300 to 500 gf). More preferably, the arithmetic mean roughness (Ra) is 1 nm to 10 nm, and more preferably 2 nm to 8 nm. Surface roughness can be measured using a Seiko Epson SPI3800N.

[0065] 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.

[0066] 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.

[0067] 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 be 3 μm or more and 30 μm or less. This is because it ensures that there are no skipped or streaked lines in the writing, that the writing performance is good, and that the writing feel and the suppression of wear of the ball seat under high writing pressure (writing load of 300 to 500 gf) are good. More specifically, it is preferable that it be 10 μm or more and 25 μm or less, and preferably 12 μm or more and 25 μm or less.

[0068] When ink is directly contained in the aforementioned ink container, an ink backflow prevention body can also be filled into the rear end of the ink. The aforementioned ink backflow prevention composition consists of a non-volatile liquid or a low-volatility liquid. Specifically, examples include petrolatum, spindle oil, castor oil, olive oil, refined mineral oil, liquid paraffin, polybutene, α-olefin, α-olefin oligomer or co-oligomer, dimethyl silicone oil, methylphenyl silicone oil, amino-modified silicone oil, polyether-modified silicone oil, fatty acid-modified silicone oil, etc., and one or more of these can be used in combination.

[0069] The non-volatile liquid and / or non-volatile liquid is preferably thickened to a suitable viscosity by adding a thickening agent. Examples of the thickening agent include silica with a hydrophobic surface treatment, fine particle silica with a methylated surface treatment, aluminum silicate, swellable mica, clay-based thickening agents such as hydrophobic treated bentonite and montmorillonite, fatty acid metal soaps such as magnesium stearate, calcium stearate, aluminum stearate, and zinc stearate, tripenzylidene sorbitol, fatty acid amides, amide-modified polyethylene wax, hydrogenated castor oil, dextrin compounds such as fatty acid dextrins, and cellulose compounds. Furthermore, the liquid ink backflow prevention body and the solid ink backflow prevention body can be used in combination.

[0070] Example 1 In Example 1, the oil-based ballpoint pen ink composition was obtained by collecting a colorant, organic solvent, alkylene oxide derivative of glycerin, phosphate ester surfactant, organic amine, and resin at 60°C using a disperser stirrer, stirring and dissolving them, and then cooling to room temperature. The specific proportions are as follows:

[0071] Pigment dispersion (carbon black, average particle size 150 nm, 20% pigment, 20% polyvinyl butyral) 40.0% by mass Alcohol solvent (benzyl alcohol) 21.0% by mass Polyoxyalkylene glyceryl ether (Formula (1), polyoxypropylene diglyceryl ether) 20.0% 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 Terpene phenol resin (weight-average molecular weight 550, softening point 100°C, hydroxyl value 60 (mgKOH / g)) 5.0% by mass Rosin-based resin (rosin ester (softening point 100-110°C)) 10.0% by mass Polyvinylpyrrolidone 0.5% by mass

[0072] Examples 2-21 As shown in Table 1, oil-based ballpoint pen ink compositions for Examples 2 to 21 were obtained using the same procedure as in Example 1, except that the ink components were changed. The measurement and evaluation results are shown in the table.

[0073] Comparative Examples 1-2 As shown in the table, Comparative Examples 1 and 2 of oil-based ballpoint pen ink compositions were obtained using the same procedure as in Example 1, except that the ink components were changed. The measurement and evaluation results are shown in the table. [Table 1] [Table 2] [Table 3]

[0074] Testing and evaluation An oil-based ballpoint pen was prepared by filling an oil-based ballpoint pen refill, which was fitted with a ballpoint pen tip (containing a coil spring that directly presses the ball against the inner wall of the tip edge, with a ball diameter of φ0.7 mm and an axial movement of the ball of the ball: 8 μm, and an arithmetic mean roughness (Ra) of the ball surface: 5 nm) into an ink container (polypropylene), and then filling the refill with the oil-based ballpoint pen. The following tests and evaluations were performed using JIS P3201 writing paper as the writing test paper.

[0075] Writing performance test (line skipping / fading): The handwriting was observed after a 100m writing test on a running test machine with a load of 200gf, a writing angle of 70°, and a speed of 4m / min. ◎...Handwriting without skipped lines or smudges. ○...Some handwriting has slight skipped lines or smudges. △···There are some skipped lines and smudges in the handwriting, but it is at a level that does not affect practical use. ×...Many skipped lines and smudges in the handwriting.

[0076] Writing feel: Evaluated through a sensory test using handwriting. ◎...very smooth ○...Smooth △···Smoothness that is acceptable for practical use. ×...heavy things

[0077] 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.

[0078] 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 brush stroke 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. ×...Those with a brush stroke length of 20mm or more.

[0079] In Examples 1-21, good performance was obtained in all tests, including writing performance (line skipping / skimming), writing feel, abrasion resistance, and initial writing performance. Furthermore, although pigments were used as colorants, the pigments exhibited good dispersibility and stability. Furthermore, the viscosity of the oil-based ballpoint pen ink compositions for Examples 1, 2, and 3 was measured using a Brookfield Viscometer RVDVII+Pro CP-52 spindle. The results were obtained at a shear rate of 5 sec in an environment of 20°C. -1 In Example 1, the ink viscosity was 3000 mPa·s at a rotation speed of 2.5 rpm, and in Example 9, the ink viscosity was 5000 mPa·s.

[0080] In Comparative Example 1, since terpene phenol resin was not used, sufficient results were not obtained in the writing performance test (line skipping and smudging).

[0081] In Comparative Example 2, since an alkylene oxide derivative of glycerin was not used, sufficient results were not obtained in the writing performance test (line skipping / smudging) and the abrasion resistance test.

[0082] Furthermore, when using retractable writing instruments such as retractable writing instruments or twist-action writing instruments (retractable ballpoint pens), the handwriting is prone to skipping lines and smudging, so using an oil-based ballpoint pen ink composition like the one of the present invention is effective.

[0083] Furthermore, in order to suppress ink leakage and improve writing performance, it is preferable to have a valve mechanism that presses a ball, which is rotatably held at the tip of the ballpoint pen tip, against the inner wall of the tip edge either directly or via a pressing body using a coil spring, thereby creating a gap between the inner wall of the tip edge and the ball due to the pressure applied during writing, allowing ink to flow out, and to close even the minute gap at the tip of the tip when not in use.

[0084] Furthermore, in this embodiment, for convenience, an oil-based ballpoint pen is shown as an example in which an oil-based ballpoint pen refill containing a writing instrument ink composition is directly contained within the barrel. However, the writing instrument of the present invention may also be a direct-fill type ballpoint pen, marking pen, or felt-tip pen in which the barrel serves as an ink storage cylinder and the writing instrument ink composition is directly contained within the barrel. Furthermore, although this embodiment uses a ballpoint pen tip formed by cutting wire as an example for convenience, a ballpoint pen tip formed by pressing pipe material may also be used. [Industrial applicability]

[0085] The present invention can be used as a writing instrument, and more specifically, it can be widely used as a ballpoint pen, such as a capped or retractable pen.

Claims

1. An oil-based ballpoint pen ink composition comprising a colorant, a terpene phenol resin, a rosin-based resin, and an alkylene oxide derivative of glycerin, wherein the alkylene oxide derivative of glycerin is polyoxyalkylene glyceryl ether.

2. The oil-based ballpoint pen ink composition according to Claim 1, characterized in that the polyoxyalkylene glyceryl ether is polyoxyalkylene diglyceryl ether.

3. The oil-based ballpoint pen ink composition according to claim 1 or 2, characterized in that the weight-average molecular weight of the terpene phenol resin is 200 or more and 1200 or less.

4. The oil-based ballpoint pen ink composition according to claim 1 or 2, characterized in that the weight-average molecular weight of the alkylene oxide derivative of glycerin is 300 or more and 5,000 or less.

5. The oil-based ballpoint pen ink composition according to claim 1 or 2, characterized in that the average number of added alkylene oxides of the alkylene oxide derivative of glycerin is 1 or more and 30 or less.

6. The oil-based ballpoint pen ink composition according to claim 1 or 2, characterized in that it comprises at least one selected from a phosphate ester surfactant, a silicone surfactant, a surfactant having an acetylene bond, a fluorine-based surfactant, a fatty acid, and a fatty acid ester.

7. An oil-based ballpoint pen characterized by having a ballpoint pen tip that rotatably holds a ball at the tip of an ink reservoir, and containing an oil-based ballpoint pen ink composition according to claim 1 or 2 in the ink reservoir.

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