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

Abstract

To provide an oil-based ballpoint pen ink composition which inhibits wear of a ball seat under high writing pressure (writing loads of 300-500 gf), improves a writing feel, and is excellent in the capability of starting writing, ink temporal stability and ink followability; and an oil-based ballpoint pen employing the same.SOLUTION: An oil-based ballpoint pen ink composition contains a colorant, an organic solvent, and a compound represented by the general formula (Chemical Formula 1).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] Writing instruments, such as ballpoint pens and marking pens, are easily affected by writing resistance between the tip and the writing surface during writing. Ballpoint pens, in particular, have a ballpoint pen tip consisting of a metal tip made of stainless steel or the like at the tip, 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 causes wear on the ball seat, resulting in problems such as skipped lines, streaking, and poor writing quality, and there was room for improvement. Furthermore, if the tip of the pen is left exposed to the air, the solvents in the ink will evaporate, and when the colorants and resins dry and solidify, it is likely to cause streaking or skipping of the ink when you start writing.

[0003] To address these issues, numerous oil-based ballpoint pen ink compositions have been proposed that utilize various lubricants to improve lubrication and reduce writing resistance between the pen tip and the writing surface during writing.

[0004] As oil-based ink compositions using such additives, those using alkyl β-D-glucoside are described 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 are described in Japanese Patent Publication No. 7-196971, "Oil-based ballpoint pen ink composition," those using N-acyl amino acids, N-acylmethyl tauric acid, and N-acylmethylalanine are described in Japanese Patent Publication No. 2007-176995, "Oil-based ballpoint pen ink," and deca macadamia nut oil fatty acid decaglyceride. As an example of a composition containing at least ceryl and a polyoxyethylene alkyl ether having 16 or more carbon atoms in the alkyl group and being solid at room temperature, see Japanese Patent Publication No. 2008-88264, "Oil-based ink composition for ballpoint pens." As an aqueous ink composition containing N-acyl amino acids and N-acylmethyl taurine, see Japanese Patent Publication No. 2003-192972, "Aqueous ink for ballpoint pens." As an aqueous ink composition containing an isoprene sulfonic acid-acrylic acid copolymer, see Japanese Patent Publication No. 2006-282870, "Aqueous ink composition for ballpoint pens." [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" [Patent Document 5] "Japanese Patent Publication No. 2003-192972" [Patent Document 6] "Japanese Patent Publication No. 2006-282870" [Overview of the project] [Problems that the invention aims to solve]

[0006] However, while some additives, such as those described in Patent Documents 1-6, can reduce writing resistance between the writing tip and the writing surface to some extent, the results were not satisfactory, and there was room for improvement. Furthermore, in recent years, in order to improve the writing feel of ballpoint pen inks, the viscosity of the ink has been reduced. However, when writing with high pressure (high pressure resistance, writing load of 300-500 gf), this can easily affect lubrication, leading to increased wear on the ball bearing and thus impacting writing performance. Therefore, there is a need to further improve lubrication and resistance to high pressure writing in order to reduce writing resistance between the pen tip and the writing surface. Furthermore, in the case of retractable ballpoint pens such as click-type or twist-type ballpoint pens, the tip of the pen tip is important because leaving it exposed to the air can easily affect its writing performance. Therefore, it is necessary to satisfy both lubricity under high writing pressure (writing load of 300-500 gf) and writing performance at the start of writing.

[0007] The object of the present invention is to obtain an oil-based ballpoint pen ink composition that suppresses wear of the ball seat under high writing pressure (writing load of 300 to 500 gf), improves writing feel, and has good initial writing performance and ink followability, as well as an oil-based ballpoint pen using the same. [Means for solving the problem]

[0008] To solve the above problems, the present invention "1. Contains no colorants, organic solvents, or compounds represented by general formula (Chemical Formula 1)." the law of nature, The organic solvent is an aromatic glycol monoether solvent. An oil-based ballpoint pen ink composition characterized by the following: [ka] 2. The oil-based ballpoint pen ink composition according to paragraph 1, characterized in that the hydroxyl value (mgKOH / g) of the general formula (Chemical Formula 1) is 100 to 1000 (mgKOH / g). 3. The oil-based ballpoint pen ink composition according to paragraph 1 or 2, characterized in that the oil-based ballpoint pen ink composition comprises a polyvinyl butyral resin or a ketone resin. 4. The oil-based ballpoint pen ink composition according to any one of paragraphs 1 to 3, characterized in that the oil-based ballpoint pen ink composition contains a nonionic surfactant. . 5. The oil-based ballpoint pen ink composition according to any one of paragraphs 1 to 4, characterized in that the oil-based ballpoint pen ink composition contains a phosphate ester-based surfactant.. 6. 20℃, shear rate 5sec -1 An oil-based ballpoint pen ink composition according to any one of paragraphs 1 to 5, characterized in that the ink viscosity is 30,000 mPa·s or less. 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 any one of paragraphs 1 to 6 within the ink reservoir. shall be set as.

Advantages of the Invention

[0009] The present invention can maintain the lubricity between the writing tip and the writing surface (including the lubricity between the ball and the chip body) by improving the lubricity, suppress the writing resistance of the writing tip, and suppress the wear of the ball seat under high writing pressure (writing load of 300 to 500 gf), improve the writing feel, and obtain an ink composition for an oil-based ballpoint pen with good writing performance and ink followability, and an oil-based ballpoint pen using the same.

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.

[0011] The present invention is characterized by an oil-based ballpoint pen ink composition comprising a colorant, an organic solvent, and a compound represented by general formula (Chemical Formula 1). This composition maintains lubrication between the writing tip and the writing surface (including lubrication between the ball and the tip body) through a lubricating layer formed by the compound represented by general formula (Chemical Formula 1), which contains alkylene oxide. This suppresses writing resistance at the writing tip, reduces wear of the ball seat under high writing pressure (writing load of 300-500 gf), improves writing feel, and further improves initial writing performance by suppressing solvent evaporation in the ink even when the writing tip is left in the atmosphere. Therefore, it is possible to suppress wear of the ball seat under high writing pressure (writing load of 300-500 gf), improve writing feel, and improve initial writing performance, making it effective and preferable when used in ballpoint pen inks. In particular, since oil-based ballpoint pens are intended for use on carbon copy paper, and therefore require higher writing pressure than usual (high-pressure writing), it is desirable that the ink performs well under high writing pressure (writing load of 300-500 gf). For this reason, when used for oil-based ballpoint pen ink, it is most effective and preferable. [ka]

[0012] (Compounds represented by general formula (Chemical Formula 1)) The compound represented by the general formula (Chemical Formula 1) used in the present invention is a compound having alkylene oxide in its structure, and examples include pentaerythritol polyoxyalkylene ether and trimethylolpropane tripolyoxyalkylene ether. Specifically, examples include pentaerythritol polyoxyalkylene ethers such as pentaerythritol polyoxypropylene ether and pentaerythritol polyoxyethylene ether, trimethylolpropane tripolyoxyalkylene ethers such as pentaerythritol polyoxypropylene ether and trimethylolpropane polyoxyethylene ether, and examples include PNT-40 (average number of moles of ethylene oxide added: 4), PNT-F40 (average number of moles of propylene oxide added: 4), TMP-F32 (propylene oxide added), TMP-30 (average number of moles of ethylene oxide added: 3), TMP-60 (average number of moles of ethylene oxide added: 6), and TMP-60 (average number of moles of ethylene oxide added: 6) (Nippon Emulsifier Co., Ltd.). These compounds, represented by the general formula (Chemical Formula 1), have alkylene oxide in their structure and are hydrophilic and lipophilic. The presence of highly polar hydrophilic groups in the structure makes them more adsorbent to the metal material of the ballpoint pen tip, thereby improving lubrication. This suppresses wear of the ball seat and improves writing feel even under high writing pressure (writing load of 300-500 gf). Furthermore, since the compound represented by general formula (Chemical Formula 1) is less likely to evaporate, it is preferable because it improves writing performance even when the writing tip is left in the air, and also improves ink followability by minimizing ink viscosity increase in the writing instrument ink composition. In addition, when a pigment is used as a colorant, the ink viscosity generally increases over time due to pigment aggregation, reducing ink followability. However, the polar groups in the structure of the compound represented by general formula (Chemical Formula 1) adsorb to the pigment surface, stably dispersing the pigment in the ink. Therefore, it is possible to improve ink followability by suppressing the increase in ink viscosity due to pigment aggregation.

[0013] Furthermore, the compound represented by the general formula (Chemical Formula 1) has many branched chains and forms a bulky structure, which makes it easier to form a thicker lubricating film and improves lubricity. This helps to suppress wear of the ball seat and improve writing feel even under high writing pressure (writing load of 300-500 gf). Therefore, it is preferable to include pentaerythritol polyoxyalkylene ether, which is represented by the general formula (Chemical Formula 2). Moreover, when used in oil-based inks, it is preferable that R1 in general formulas (Chemical Formula 1) and (Chemical Formula 2) is a methyl group. This is because having a propylene oxide group provides excellent lipophilicity, making it more stable in the ink and easier to obtain the effects of the present invention. Considering this further, it is preferable to include pentaerythritol polyoxypropylene ether in general formula (Chemical Formula 2) where R1 is a methyl group. [ka]

[0014] The compounds represented by the above general formulas (Chemical Formula 1) and (Chemical Formula 2) preferably have an average number of added alkylene oxide moles (k+l+m+n) of 1 to 20, considering the suppression of ball seat wear under high writing pressure (writing load of 300 to 500 gf), improved writing feel, and further improved initial writing performance. Furthermore, considering greater stability in the ink to facilitate obtaining the effects of the present invention, the average number of added alkylene oxide moles is preferably 1 to 15. Moreover, considering the suppression of ball seat wear under high writing pressure, improved writing feel, and improved initial writing performance, the average number of added alkylene moles is preferably 1 to 10, and further preferably 1 to 6. In particular, considering the suppression of wear of the ball seat under high writing pressure, it is preferable that R1 be a methyl group, and in that case, the average number of moles of propylene oxide added (k+l+m+n) is preferably 1 to 20, and more preferably 1 to 15, 1 to 10, and even more preferably 1 to 6.

[0015] Furthermore, the hydroxyl value (mgKOH / g) of the compound represented by the general formula (Chemical Formula 1) is preferably 100 to 1000 (mgKOH / g). This is because, within this range, the stability with colorants and other components is less affected, and the effects of the present invention are more easily obtained. More preferably, it is 300 to 800 (mgKOH / g), and even more preferably, it is 500 to 750 (mgKOH / g). Furthermore, the average weight molecular weight of the compound represented by the general formula (Chemical Formula 1) is preferably 2000 or less. This is because if the average weight molecular weight is too high, it tends to affect the stability over time in the oil-based ink, making it difficult to obtain the effects of the present invention. More specifically, the average weight molecular weight is preferably 1000 or less. The weight-average molecular weight is a value obtained using GPC (gel permeation chromatography) in terms of polystyrene equivalent.

[0016] Furthermore, if the content of the compound represented by the general formula (Chemical Formula 1) is less than 0.1% by mass of the total amount of the ink composition, the effects of suppressing wear of the ball seat under high writing pressure, as well as the writing feel, initial writing performance, and ink followability described above may not be obtained. If it exceeds 40% by mass, it may affect the ink's stability over time. Therefore, the content is preferably 0.1 to 40% by mass of the total amount of the ink composition, preferably 1 to 30% by mass if the above effects are taken into consideration, preferably 3 to 25% by mass if the balance between suppressing wear of the ball seat and the writing feel, initial writing performance, and ink followability is taken into consideration, and most preferably 8 to 25% by mass.

[0017] (solvent) In this invention, ① Ink composition for oil-based ballpoint pens The solvent used may be water, an organic solvent, or a mixture of water and an organic solvent. As for the water, conventional waters such as deionized water, distilled water, and tap water may be used.

[0018] Examples of organic solvents include non-water-soluble organic solvents and water-soluble organic solvents. Specifically, examples 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, ethylene glycol, diethylene glycol, and glycerin; 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. These are organic solvents commonly used in oil-based ballpoint pen ink compositions and water-based ballpoint pen ink compositions.

[0019] Among these organic solvents, aromatic alcohols are preferable because they have an aromatic ring which improves lubricity and readily dissolve and stabilize with the compound represented by the general formula (Chemical Formula 1). Furthermore, using a glycol ether solvent is more effective because it readily absorbs moisture, which softens the strength of the film formed when the tip of the pen dries, thereby improving writing performance. Therefore, when using a compound represented by the general formula (Chemical Formula 1) as in the present invention, it is preferable to use an aromatic glycol ether solvent, considering lubricity and writing performance.

[0020] Furthermore, considering improvements in solubility, lubricity, and ink drying properties, the solvent content is preferably 10 to 90% by mass of the total ink composition, more preferably 20 to 90% by mass, and more preferably 40 to 70% by mass.

[0021] (Coloring agent) The colorants used in the aqueous ink composition and oil-based ink composition of the present invention are not particularly limited and can be selected and used as appropriate, such as dyes and pigments. Dyes and pigments may also be used in combination.

[0022] Furthermore, when considering lubrication, it is preferable to use pigments as colorants. This is because pigment particles can easily fill the gap between the ball and the tip body, acting like bearings and suppressing metal contact, thereby improving lubrication, enhancing writing feel, and reducing wear on the ball seat. In addition, pigments are preferable because they have excellent water resistance and lightfastness, resulting in good ink fastness. In particular, the synergistic effect of the compound represented by general formula (Chemical Formula 1), the lubricating layer formed by the nonionic surfactant or phosphate ester surfactant described later, and the pigment particles and bearing action makes it easier to maintain lubrication, suppress wear of the ball seat, and improve writing feel. Furthermore, considering the gap relationship inside the ballpoint pen tip, the average particle diameter is preferably 1 to 500 nm. More preferably, it is 30 to 350 nm, and even more preferably, 50 to 300 nm. Here, the average particle diameter can be determined by the laser diffraction method, specifically by the particle diameter (D50) at 50% volume accumulation of the particle size distribution measured using a laser diffraction particle size distribution analyzer (product name "MicrotracHRA9320-X100", Nikkiso Co., Ltd.) based on values ​​calibrated using standard samples or 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. In addition, the pigment is preferable because it has excellent water resistance and lightfastness and can produce good color development.

[0023] Furthermore, when using dyes, it is preferable to use salt-forming dyes, taking into consideration the stability over time due to their compatibility with the compound represented by the general formula (Chemical Formula 1). Moreover, 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 acidic dyes and basic dyes, or salt-forming dyes of acidic dyes and organic amines. If stability with the components in the ink is considered even more important, salt-forming dyes of basic dyes and organic acids are preferred.

[0024] Dyes used in oil-based ink compositions include oil-soluble dyes, acid dyes, basic dyes, and gold-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. Considering the stability with the compound represented by the general formula (Chemical Formula 1) used in the present invention, it is preferable to use salt-forming dyes. 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.).

[0025] Suitable dyes for use in water-based ink compositions include direct dyes, acid dyes, basic dyes, metal-containing dyes, and various salt-forming dyes. (a) Direct dyes include Direct Yellow 4, 26, 44, 50, 85, Direct Red 1, 2, 4, 23, 31, 37, 39, 75, 80, 81, 83, 225, 226, 227, Direct Blue 1, 3, 15, 41, 71, 86, 106, 119, Direct Orange 6, etc. (b) Acid dyes and For example, Acid Black 1, 2, 24, 26, 31, 52, 107, Acid Orange 56, Acid Yellow 3, 7, 17, 19, 23, 42, 49, 61, 92, Acid Red 8, 9, 14, 18, 51, 52, 73, 87, 92, 94, Acid Blue 1, 7, 9, 22, 62, 90, and so on. (c) Basic dyes include CI Basic Yellow-1, CI Basic Yellow-2

[0026] The colorant content is preferably 5.0 to 30.0% by mass relative to the total amount of the ink composition. This is because if it is less than 5.0% by mass, it tends not to produce dark writing, and if it exceeds 30.0% by mass, it tends to affect solubility in the ink. Considering this tendency more carefully, 7.0 to 25.0% by mass is preferred, and if further considered, 10.0 to 20.0% by mass is even more preferred.

[0027] (Surfactants) In the present invention, the use of a surfactant is preferable. This is because it softens the film formed by resins and other components contained in the ink, making it easier to improve writing performance and further improve lubricity, thereby improving the writing feel. While there are nonionic surfactants, anionic surfactants, and cationic surfactants, the use of a nonionic surfactant is preferable. This is because it does not easily exhibit ionic properties, and precipitates caused by other components in the ink are less likely to occur, resulting in good ink stability over time, which is why it is preferable. With regard to the nonionic surfactant, it is preferable that the HLB value be 16 or less, considering the ink's stability over time. If the ink's stability over time is considered even more carefully, it is preferable that the HLB value be between 3 and 14, and if the stability is considered even more carefully, it is preferable that the HLB value be between 3 and 11. Furthermore, HLB can be determined using methods such as the Griffin method. In particular, in retractable writing instruments such as click-type and twist-type writing instruments, unlike capped writing instruments, the pen tip is always exposed to the outside, which easily affects the writing performance when the writing tip is dry. Therefore, it is more preferable to use a surfactant with the above HLB value.

[0028] Furthermore, examples of nonionic surfactants include fatty acid esters, polyalkylene alkyl ethers, polyoxyethylene alkylamines, alkylimidazolines, alkyl alkanolamides, oxyethylene oxypropylene block copolymers, and surfactants having acetylene bonds. Among these, considering the above-mentioned writing performance and ink stability over time, it is preferable to select one or more from fatty acid esters, polyalkylene alkyl ethers, polyoxyethylene alkylamines, alkylimidazolines, and alkyl alkanolamides, and if further improvement in writing performance is considered, it is preferable to use fatty acid esters. These may be used individually or in combination of two or more.

[0029] Furthermore, examples of the fatty acid esters include sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid esters, glycerin fatty acid esters, polyglycerin fatty acid esters, and polyoxyethylene fatty acid esters. However, considering the interaction with polyoxyalkylene glyceryl ether and the write performance, it is preferable to select one or more from sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, glycerin fatty acid esters, and alkylimidazolines. Moreover, it is preferable to use sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, and alkylimidazolines, which have a cyclic skeleton structure. Further consideration is given to selecting one or more from sorbitan fatty acid esters, such as sorbitan fatty acid esters or polyoxyethylene sorbitan fatty acid esters, because they have multiple hydroxyl groups and readily exhibit hygroscopic properties.

[0030] Furthermore, among the sorbitan fatty acid esters, considering the writing performance, it is preferable that the alkyl group of the sorbitan fatty acid ester has 1 to 20 carbon atoms. Moreover, considering that the length is suitable for forming a lubricating layer, and that this makes it easier to suppress wear of the ball seat under high writing pressure, it is preferable to use sorbitan fatty acid esters in which the alkyl group has 10 to 20 carbon atoms. More specifically, it is preferable to use sorbitan fatty acid esters in which the alkyl group has 12 to 18 carbon atoms. The sorbitan fatty acid esters mentioned above specifically include sorbitan fatty acid esters such as sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, sorbitan monooleate, sorbitan monococoate, sorbitan dilaurate, sorbitan distearate, sorbitan dioleate, sorbitan trioleate, sorbitan trystearate and their composites, and polyoxyethylene sorbitan fatty acid esters such as polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monopalmitate, polyoxyethylene sorbitan monostearate, polyoxyethylene sorbitan trioleate, polyoxyethylene sorbitan trystearate and their composites.

[0031] The content of nonionic surfactant is more preferably 0.1 to 15% by mass relative to the total amount of ink composition. This is because if it is less than 0.1% by mass, it is difficult to suppress wear of the ball seat under the desired high writing pressure (writing load of 300 to 500 gf), improve the writing feel, and obtain the desired initial writing performance and ink followability. If it exceeds 15% by mass, the ink tends to become unstable over time. Considering this tendency, 0.5 to 10% by mass relative to the total amount of ink composition is preferable, and more preferably, 1 to 5% by mass is most preferable.

[0032] In the present invention, considering the improvement of lubricity of the writing tip (the ball and ball seat of the ballpoint pen), the suppression of wear of the ball seat under high writing pressure (writing load of 300-500 gf), the improvement of writing feel, and the further improvement of the writing performance when the writing tip is left in the air and dries, it is preferable that the product contains a phosphate ester surfactant and a fatty acid, and if lubricity is considered even more, it is preferable that the product contains a phosphate ester surfactant. This is because, having phosphate groups and fatty acid groups, it readily adsorbs to metal surfaces, and in particular, it forms a lubricating film between the ball and the ball seat, thereby improving lubrication, suppressing wear of the ball seat under high writing pressure (writing load of 300-500 gf), and improving writing feel. Therefore, considering that using a phosphate ester surfactant, a fatty acid, and the compound represented by the general formula (Chemical Formula 1) allows the lubricating effects of both to work synergistically to further improve lubrication between the ball and the ball seat, and thus more effectively suppressing wear of the ball seat under higher writing pressure (writing load of 300-500 gf), a phosphate ester surfactant is preferred. Furthermore, phosphate ester surfactants have a rust-preventive effect, so when the ball is made of metal, they are preferable because they suppress corrosion of the ball, thereby improving writing quality and reducing wear on the ball seat. Moreover, when used as the ball material, cobalt, nickel, chromium, etc. are used as the binder, and since these metals are less susceptible to corrosion over time, they do not cause rotational resistance of the ball due to corrosion, thus improving writing quality and reducing wear on the ball seat. In particular, in the case of cemented carbide balls with tungsten carbide as the main component, cobalt, nickel, chromium, etc. are used as the binder, making them effective and preferable. Therefore, in the present invention, it is effective and preferable to use a phosphate ester surfactant in combination with the compound represented by the general formula (Chemical Formula 1). Furthermore, considering the need to achieve a good balance between writing feel and suppression of ball seat wear, it is effective and preferable to use a nonionic surfactant in combination with a phosphate ester surfactant and the compound represented by the general formula (Chemical Formula 1). Furthermore, in the present invention, when polyvinyl butyral is used, using a phosphate ester-based surfactant is preferable because the lubrication is more easily and effectively improved by the combination of the lubricating layer made of polyvinyl butyral and the lubricating film made of the phosphate ester-based surfactant.

[0033] In the case of the phosphate ester surfactant, if we consider improving both lubricity and writing performance through interaction with the compound represented by the general formula (Chemical Formula 1), it is preferable that the HLB value be between 6 and 18. This is because if the HLB value exceeds 18, hydrophilicity tends to increase, and solubility in ink tends to decrease, making it difficult to obtain the effect of the phosphate ester surfactant through interaction with the compound represented by the general formula (Chemical Formula 1), and in particular, it becomes difficult to obtain a lubricating effect. Also, if the HLB value is less than 6, the lipophilicity becomes too strong, which tends to affect compatibility with organic solvents, making it difficult to obtain ink stability over time, and further improving writing performance. Furthermore, if we consider suppressing wear of the ball seat under even higher writing pressure, it is preferable that the HLB value be 17 or less, and therefore preferably between 6 and 17, and if we consider writing performance even more, an HLB value of 7 to 17 is preferable. In particular, in retractable ballpoint pens such as retractable ballpoint pens and twist-action ballpoint pens, unlike capped ballpoint pens, the pen tip is always exposed to the outside, which easily affects the writing performance when the writing tip is dry. Therefore, it is more preferable to use a phosphate ester surfactant with the above HLB value. The HLB can be determined by methods such as the Griffin method or the Kawakami method.

[0034] Phosphate ester surfactants include those with an alkoxy group (C a H 2a+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. Among these, considering the suppression of ball seat wear under high writing pressure (writing load of 300-500 gf), it is preferable to use a phosphate ester surfactant having an alkyl group, and 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, lubricity tends to be insufficient, and if the number of carbon atoms is too many, it tends to affect the ink's stability over time.

[0035] Furthermore, when using phosphate ester surfactants, the acid value is preferably 200 or less. This is to facilitate the improvement in lubricity provided by the phosphate ester surfactant. Considering stability in the ink and lubricity, an acid value of 30 to 170 is preferable, and if even more considerations are taken into account, an acid value of 40 to 160 is preferable. The acid value shall be expressed as the number of milligrams of potassium hydroxide required to neutralize the acidic components contained in 1 g of the sample.

[0036] In the present invention, the blending ratio of the compound represented by the general formula (Chemical Formula 1) to the surfactant, such as the nonionic surfactant or phosphate ester surfactant described above (compound represented by the general formula (Chemical Formula 1) / surfactant) is preferably 1 to 40 times by mass, more preferably 2 to 30 times, preferably 1 to 25 times, and most preferably 1 to 15 times. Within this range, it is possible to balance the suppression of ball bearing wear with the improvement of writing feel, initial writing performance, and ink followability.

[0037] (Stabilizer) In the present invention, when surfactants such as phosphate ester surfactants are used, neutralization is preferable because it easily improves the writing feel and initial writing performance by solubility in the ink. Examples of stabilizers include basic inorganic compounds such as ammonia, sodium carbonate, sodium phosphate, and sodium hydroxide; alkanolamines such as diethanolamine and triethanolamine; amines containing ethylene oxide such as oxyethylene alkylamine and polyoxyethylene alkylamine; alkylamines such as laurylamine and stearylamine; aliphatic amines such as distearylamine, dimethyl laurylamine, dimethylstearylamine, and dimethyloctylamine; basic organic compounds such as sodium acetate; lactic acid and citric acid. Among these, amines containing ethylene oxide, dimethylalkylamines, and alkanolamines are preferred when considering stability with surfactants. In particular, for oil-based ink compositions, amines containing ethylene oxide and dimethylalkylamines are preferred. Furthermore, considering the suppression of ball seat wear under high writing pressure (writing load of 300-500 gf), amines containing ethylene oxide are preferred. For aqueous ink compositions, alkanolamines are preferred, and it is preferable to use triethanolamine, which is weakly basic. These may be used individually or in combination of two or more.

[0038] Furthermore, the total amine value of the organic amine is preferably 100 to 300 (mgKOH / g), considering its stability with the surfactant, phosphate ester surfactant, colorant, and other components. This is because if it exceeds 300 (mgKOH / g), the reactivity is strong, making it more likely to react with the above components, which tends to impair the ink's stability over time. Also, if the total amine value is less than 100 (mgKOH / g), it tends to affect the stability of the surfactant and phosphate ester surfactant in the ink. In the case of an oil-based ballpoint pen, this tends to impair the adsorption of metals such as the ball and tip body, making it difficult to obtain lubrication performance. If stability with the above components and lubricity are considered, a range of 150 to 300 (mgKOH / g) is preferable, if stability is considered, 180 to 300 (mgKOH / g) is preferable, and if stability is considered even more, 230 to 270 (mgKOH / g) is preferable. 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.

[0039] The content of the stabilizer is preferably 0.1 to 10% by mass of the total ink composition, considering neutralization stability with the surfactant, more preferably 0.1 to 8% by mass, and more preferably 0.5 to 6% by mass, considering neutralization with respect to the surfactant.

[0040] (resin) Furthermore, in the present invention, resins may be used as ink viscosity modifiers, ink leakage inhibitors, pigment dispersants, and fixatives. Examples of resins include polyvinyl butyral resin, ketone resin, polyacetal resin, polyvinyl alcohol resin, cellulose resin, terpene resin, alkyd resin, phenoxy resin, polyvinyl acetate resin, polyvinylpyrrolidone resin, ethylene oxide polymer, acrylic resin, styrene-acrylic resin, styrene-maleic acid resin, and resin particles such as olefin resin particles, acrylic acid ester resin particles, amino resin particles, acrylic resin particles, and styrene-butadiene resin particles. These may be used individually or in combination of two or more. Among these resins, in order to further improve ink leakage inhibition, it is preferable that the resin used as an ink viscosity modifier contains polyvinyl butyral resin or ketone resin.

[0041] Polyvinyl butyral resin is also preferable because it easily forms a lubricating layer that provides a higher lubrication effect. This is because using polyvinyl butyral resin forms an elastic ink layer between the ball and the ball seat, making direct contact difficult and thus improving the writing feel. Furthermore, the synergistic effect of the lubricating layer formed by using it in combination with the compound represented by the general formula (Chemical Formula 1) makes it easier to obtain a higher lubrication effect. In addition, using polyvinyl butyral resin is preferable because the formed film makes it easier to improve ink leakage. Moreover, when a pigment is used as a coloring agent, a pigment dispersion effect is also obtained, making the use of polyvinyl butyral resin preferable. Here, polyvinyl butyral resin is produced by reacting polyvinyl alcohol (PVA) with butyraldehyde (BA), and has a structure containing butyral groups, acetyl groups, and hydroxyl groups.

[0042] 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 organic solvents, making it difficult to obtain sufficient lubrication and ink leakage suppression effects. Moreover, considering the writing performance due to hygroscopicity, it is preferable to use polyvinyl butyral resin with a hydroxyl group content of 25 mol% or more. In addition, polyvinyl butyral resins with a hydroxyl group content of 30 mol% or more are preferable because they tend to improve the writing feel. This is because, during writing, frictional heat is generated by the rotation of the ball, warming the ink at the tip of the pen and raising the temperature of the ink. However, unlike other resins, polyvinyl butyral resin has the property of not easily decreasing in viscosity even when the ink temperature rises, and it always forms an elastic ink layer between the ball and the ball seat, making direct contact difficult, thus tending to improve the writing feel. This is effective and preferable when used in ballpoint pen ink. In particular, since oil-based ballpoint pens are intended for use on carbon copy paper, and therefore require higher writing pressure than usual (high-pressure writing), good performance under high writing pressure (writing load of 300-500 gf) is desirable. For this reason, when used in ink for oil-based ballpoint pens, this is the most effective and preferable option. Furthermore, using polyvinyl butyral resin with a hydroxyl group content exceeding 40 mol% tends to increase moisture absorption, which can easily affect the long-term stability with the ink components. Therefore, polyvinyl butyral resin with a hydroxyl group content of 40 mol% or less is preferable. For this reason, polyvinyl butyral resin with a hydroxyl group content of 30-40 mol% is preferred, and more preferably, a hydroxyl group content of 30-36 mol% is preferred. 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%).

[0043] Furthermore, regarding the average degree of polymerization of the polyvinyl butyral resin, if the average degree of polymerization is 200 or higher, the ink leakage suppression performance tends to improve, and if the average degree of polymerization exceeds 2500, the ink viscosity tends to become too high, affecting the writing feel. Therefore, the average degree of polymerization is preferably between 200 and 2500. More specifically, the average degree of polymerization is preferably 1500 or lower, and considering the mutual lubricating effect with the compound represented by the general formula (Chemical Formula 1), the average degree of polymerization is preferably between 200 and 1000. Here, the average degree of polymerization refers to the number of basic units constituting one molecule of polyvinyl butyral resin, and a value measured based on the method specified in JIS K6728 (2001 edition) can be used.

[0044] The polyvinyl butyral resin content in the oil-based ballpoint pen ink composition should be 50% or more of the total resin content, and it is preferable to use it as the main resin. This is because if the polyvinyl butyral resin content is less than 50% of the total resin content, the other resins tend to inhibit the formation of an elastic ink layer, making it difficult to obtain the effect of improving writing feel. Furthermore, it tends to inhibit the formation of a resin coating at the tip of the pen, making it difficult to suppress ink dripping, and further inhibiting the formation of an elastic ink layer, making it difficult to obtain the effect of improving writing feel. Considering the tendency to further improve writing feel and ink drip performance, the polyvinyl butyral resin content is preferably 70% or more, and preferably 90% or more, of the total resin content.

[0045] If the resin content is less than 1% by mass relative to the total amount of ink composition, the desired lubricity and ink leakage suppression performance tend to be inferior, and if it exceeds 40% by mass, the solubility in the ink tends to be inferior. Therefore, a content of 1 to 40% by mass relative to the total amount of ink composition is preferable. Furthermore, if considered, 5% or more by mass is preferable, and if it exceeds 30% by mass, the ink viscosity tends to become too high, affecting the writing feel. Therefore, 5 to 30% by mass is preferable, and if considered more carefully, 10 to 25% by mass is preferable.

[0046] In addition, other materials such as viscosity modifiers, including plasticizers like fatty acid amides and hydrogenated castor oil, as well as colorants, stabilizers, plasticizers, and chelating agents, may be used as appropriate. These may be used individually or in combination of two or more.

[0047] The viscosity of the ink composition for writing instruments of the present invention is not particularly limited, but in the case of an oil-based ink composition, at 20°C and a shear rate of 5 sec, -1 When the ink viscosity (at rest) exceeds 30,000 mPa·s, the initial writing performance, writing feel, and ink followability tend to deteriorate. (20°C, shear speed 5 sec) -1 The ink viscosity (at rest) is preferably 30,000 mPa·s or less. -1 If the ink viscosity (at rest) is less than 500 mPa·s, it is difficult to suppress ink leakage, so it is preferable to set it to 500 mPa·s or higher. Considering further improvement in ink leakage suppression, writing feel, ink followability, and initial writing performance, the ink viscosity is more preferably 500 to 25000 mPa·s, more preferably 800 to 25000 mPa·s, and if writing feel and initial writing performance are given further consideration, 1000 to 20000 mPa·s is preferable. Considering further improvement in writing feel and increased ink consumption to produce darker lines, 500 to 10000 mPa·s is preferable, and if given further consideration, 1000 to 5000 mPa·s is preferable. For water-based ink compositions, the temperature is 20°C and the shear rate is 1.92 sec. -1 The ink viscosity (at rest) is preferably 500 to 5000 mPa·s, more preferably 500 to 3500 mPa·s, and even more preferably 1000 to 3000 mPa·s. Here, the ink viscosity of the aqueous ink composition was measured using a Brookfield DV-II viscometer (CPE-42 rotor).

[0048] (Ballpoint pen) The ink composition for writing instruments according to the present invention can be applied to various types of ballpoint pens, but it is particularly preferable to use it in retractable ballpoint pens such as retractable or twist-action ballpoint pens. Such a ballpoint pen comprises a container that houses the ink composition for writing instruments according to the present invention, and a ballpoint pen tip located at the tip of the container, which rotatably holds a ball in a ball-holding chamber. The ballpoint pen tip can be extended and retracted from the opening at the tip of the barrel, and has a structure generally known as a retractable ballpoint pen. Generally, when an ink composition is used in a retractable ballpoint pen where the pen tip is not sealed, the tip is constantly exposed to the air, causing the tip to dry out and making it prone to skipping or smudging when writing begins. However, using the composition according to the present invention improves such problems, making it preferable.

[0049] (Ballpoint pen tip) Furthermore, in the case of ballpoint pens, the amount of movement of the ball of the ballpoint pen tip in the vertical axis direction is preferably 50 μm or less. In the case of oil-based ballpoint pens, it is preferably 3 to 30 μm. This is because if it is less than 3 μm, it becomes difficult to obtain a good writing feel and suppression of ink smudging, and if it exceeds 30 μm, it tends to affect ink leakage suppression, ink blotting, and ink-following performance. If given more consideration, it is preferable to set it to 3 to 25 μm, and if given even more consideration, it is preferable to set the amount of movement in the vertical axis direction to 7 to 20 μm. In the case of water-based ballpoint pens, it is preferably 15 to 50 μm. This is because if it is less than 15 μm, it becomes difficult to obtain a good writing feel and suppression of ink smudging, and if it exceeds 50 μm, it tends to affect ink leakage suppression, ink blotting, and ink-following performance. If given more consideration, it is preferable to set it to 20 to 50 μm, and if given even more consideration, it is preferable to set the amount of movement in the vertical axis direction to 25 to 45 μm. The axial movement (clearance) of the ball of the ballpoint pen tip refers to the distance the ball can move in the vertical axis direction of the ballpoint pen tip body.

[0050] Furthermore, the arithmetic mean roughness (Ra) of the ball surface of the ballpoint pen tip used in the present invention is preferably 0.1 to 12 nm. This is because if the arithmetic mean roughness (Ra) is less than 0.1 nm, it is difficult for sufficient ink to adhere to the ball surface, making it difficult to obtain a dark line when writing, and causing skipped lines and streaks in the writing. If the arithmetic mean roughness (Ra) exceeds 12 nm, the ball surface is too rough, resulting in high rotational resistance between the ball and the ball seat, which can lead to wear of the ball seat and poor writing quality, as well as affecting writing performance such as streaks, skipped lines, and uneven lines. Moreover, if the arithmetic mean roughness (Ra) is 0.1 to 10 nm, it is more preferable when using an ink composition like the one of the present invention, as it improves writing quality and allows ink to adhere more easily to the ball surface. If writing quality is further considered, 2 to 8 nm is preferable. Regarding the arithmetic mean roughness of the ball surface, the arithmetic mean roughness (Ra) is the value obtained by taking a sample of roughness from the roughness curve measured by a surface roughness measuring instrument (model name SPI3800N, manufactured by Seiko Epson), taking a sample of a reference length in the direction of the mean line, summing the absolute values ​​of the deviations from the mean line to the measurement curve of this sampled portion, and then averaging the result.

[0051] 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.

[0052] 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.

[0053] The ink consumption of a ballpoint pen is preferably 20 to 120 mg per 100 m. This is because if the ink consumption is less than 20 mg per 100 m, ink smudging and unevenness are likely to occur, making it difficult to obtain dark lines and a good writing feel. If the ink consumption exceeds 120 mg per 100 m, it affects ink tracking, makes ink leakage more likely through the gap between the ball and the tip, and also makes ink blobs more likely. Considering the above effects, the ink consumption of a ballpoint pen is preferably 25 to 100 mg per 100 m, and more preferably 30 to 90 mg per 100 m. 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.

[0054] Furthermore, to improve darker writing, writing feel, ink followability, and ink leakage suppression, it is effective to consider not only the ink consumption but also its relationship with the ball diameter. Specifically, the ratio of ball diameter (mm) to ink consumption (mg) per 100m of an oil-based ballpoint pen (ball diameter:ink consumption) should be 1:40 to 1:140. This is preferable because it makes it easier to obtain darker writing, better writing feel, ink followability, and ink leakage suppression. If further consideration is given, a ratio of 1:50 to 1:130 is preferable, and a ratio of 1:60 to 1:120 is preferable. 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.

[0055] (Examples) The present invention will now be explained with reference to examples. The ink composition for writing instruments (oil-based ballpoint pen ink composition) of Example 1 was prepared by first adding an organic solvent, pigment, and pigment dispersant, and dispersing them in a three-roll disperser to create a pigment dispersion. Then, the pigment dispersion, organic solvent, a compound in which R1 of general formula (Chemical Formula 2) is a methyl group (pentaerythritol polyoxyalkylene ether), a nonionic surfactant, polyvinylpyrrolidone, and polyvinyl butyral resin were used, weighed in predetermined amounts, heated to 60°C, and then completely dissolved using a disperser stirrer to obtain the ink composition for writing instruments (oil-based ballpoint pen ink composition). The specific blending amounts are as follows. Furthermore, using a Brookfield Corporation Viscometer RVDVII+Pro CP-52 spindle, the shear rate was measured at 5 seconds in an environment of 20°C. -1 When the ink viscosity of Example 1 was measured at a rotation speed of 2.5 rpm, the ink viscosity was found to be 3000 mPa·s.

[0056] Example 1 <Ink composition for oil-based ballpoint pens> Pigment dispersion (containing 20% ​​pigment and 20% polyvinyl butyral) 50.0% by mass Alcohol solvent (benzyl alcohol) 26.5% by mass In general formula (Chemical Formula 2), R1 is a methyl group (pentaerythritol polyoxyalkylene ether) 20.0% by mass Nonionic surfactant (sorbitan fatty acid ester) 2.0% by mass Polyvinylpyrrolidone 0.5% by mass Polyvinyl butyral resin 1.0% by mass

[0057] Testing and evaluation The ink compositions for oil-based ballpoint pens prepared in Examples 1 to 21 and Comparative Examples 1 to 3 were placed at the tip of an ink storage cylinder (made of polypropylene), and a ballpoint pen tip (having a coil spring in the tip that directly presses a ball (φ0.7 mm, arithmetic mean roughness (Ra) of the ball surface: 7 nm) against the inner wall of the tip edge of the tip, with an axial movement amount of the ball: 12 μm) that rotatably holds the ball was attached. At the same time, 0.2 g of the oil-based ballpoint pen ink of Example 1 was directly stored in the ink storage cylinder, and a ballpoint pen refill was arranged in an oil-based ballpoint pen (trade name: Acroball (registered trademark)) manufactured by Pilot Corporation. An oil-based ballpoint pen was produced, and the following tests and evaluations were conducted using JIS P3201 writing paper as the writing test paper. When the ink consumption per initial 100 m of Example 1 and Example 3 was measured in an oil-based ballpoint pen by performing a spiral writing test, it was 70 mg / 100 m and 75 mg / 100 m, respectively.

[0058] Examples 2 to 21 As shown in the table, ink was formulated in the same procedure as in Example 1 except that each component was changed, and ink compositions for writing instruments (ink compositions for oil-based ballpoint pens) of Examples 2 to 21 were obtained. The evaluation results are shown in the table. In addition, when the ink viscosity of Example 3 was measured using a viscometer RVDVII+Pro CP-52 spindle manufactured by Brookfield Corporation, in an environment of 20 °C, shear rate 5 sec -1 (rotation speed 2.5 rpm), for Example 3: ink viscosity = 2000 mPa·s.

[0059] Comparative Examples 1 to 3 As shown in the table, ink compositions for writing instruments (ink compositions for oil-based ballpoint pens) of Comparative Examples 1 to 3 were obtained in the same procedure as in Example 1 except that each component was changed. The evaluation results are shown in the table.

[0060] reference Example 101 <Ink Composition for Water-Based Ballpoint Pen> A pigment dispersion, water, polyhydric alcohol, a compound in which R1 of general formula (Chemical Formula 2) is a methyl group (pentaerythritol polyoxyalkylene ether), organic resin particles, a stabilizer, a phosphate ester surfactant, and a rust inhibitor were used as colorants. A predetermined amount of these was weighed, heated to 60°C, and then completely dissolved using a disperser stirrer to prepare a base ink. Subsequently, while heating the prepared base ink, a shear viscosity reducing agent was added and thoroughly mixed and stirred using a homogenizer stirrer until a uniform state was obtained to obtain the aqueous ballpoint pen ink composition of Example 1. The specific proportions of the ingredients are as follows. still, reference The ink viscosity for Example 101 was measured using a Brookfield DV-II viscometer (CPE-42 rotor) at 20°C with a shear rate of 1.92 sec. -1 When the ink viscosity was measured under the condition of a rotation speed of 0.5 rpm, it was found to be 1600 mPa·s.

[0061] Pigment dispersion (colored resin particles, solid content 34%) 20.0% by mass Water 66.2% by mass Polyhydric alcohol (glycerin) 10.0% by mass General formula (Chemical Formula 2): R1 is a methyl group (pentaerythritol polyoxyalkylene ether) 3.0% by mass Organic resin particles (olefin resin) 1.0% by mass Stabilizer (triethanolamine) 2.0% by mass Phosphate ester surfactant (HLB value: 11.5) 1.0% by mass Rust inhibitor (benzotriazole) 0.5% by mass Shear viscosity reducing agent (succinoglycan) 0.3% by mass

[0062] < reference Example 102> reference A water-based ballpoint pen ink composition was obtained using the same method as in Example 101, except that the amount of methyl group (pentaerythritol polyoxyalkylene ether) added to R1 of general formula (Chemical Formula 2) was reduced by 5%, and the amount of water was reduced accordingly.

[0063] reference A ballpoint pen was prepared by filling a refill containing a ballpoint pen with the aqueous ballpoint pen ink composition (1.0 g) prepared in Examples 101-102. The refill was fitted with a ballpoint pen tip (with a coil spring inside the tip that directly presses the ball against the inner wall of the tip edge, with a longitudinal axial movement of the ball of 30 μm and an arithmetic mean roughness (Ra) of the ball surface of 1 nm) that rotatably holds a ball with a ball diameter of φ0.7 mm, and the ball's longitudinal axial movement is 30 μm. A ballpoint pen was then prepared. The following tests and evaluations were performed using JIS P3201 writing paper as the writing test paper. [Table 1] [Table 2]

[0064] 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 bearing wear of less than 5 μm ···◎ 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 the pen is still writable. ...△ The ball bearing is severely worn, causing poor writing performance...

[0065] Writing feel: Evaluated through a sensory test using handwriting. Extremely smooth ···◎ Smooth ···○ Smoothness that is acceptable for practical use...△ Heavy items ···×

[0066] 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. The length of the ink smudge is less than 5mm ···◎ The length of the fading or smudging in the writing is 5mm or more but less than 10mm. ···○ The length of the fading or smudging in the writing is between 10mm and 20mm. ···△ The length of the fading or smudging in the writing is 20mm or longer. ···×

[0067] Ink tracking performance test: After one month in a 50°C environment, continuous rapid handwriting was performed for 10 seconds. No smudging or skipped lines in the handwriting ···◎ There were some slight smudges and skipped lines, but it was at a level that did not cause any practical problems. Some had smudged or skipped lines... △ The handwriting was smudged and the lines were skipped... ×

[0068] In Examples 1-21 (oil-based ballpoint pens), good performance was obtained in all tests, including abrasion resistance (abrasion test of the ball seat), writing feel, initial writing performance, and ink followability performance. In Examples 1-21 and 101-102, the writing instrument ink compositions containing pigments as colorants exhibited good pigment dispersibility and stability. In Examples 101-102 (water-based ballpoint pens), abrasion resistance tests (under the conditions of a load of 100 gf, a writing angle of 70°, and a writing speed of 4 m / min), writing feel and initial writing performance tests (under the conditions of a writing load of 100 gf, a writing angle of 70°, and a writing speed of 4 m / min), and ink followability tests were conducted, and good performance was obtained in all tests.

[0069] Furthermore, as Example 22, an oil-based ballpoint pen was created using the writing instrument ink composition (oil-based ballpoint pen ink composition) of Example 1, but with a ball (φ0.7 mm, arithmetic mean roughness (Ra): 2 nm) modified; as Example 23, an oil-based ballpoint pen was created using the writing instrument ink composition (oil-based ballpoint pen ink composition) of Example 1, but with a ball (φ0.7 mm, arithmetic mean roughness (Ra): 3 nm) modified; and as Example 24, a ballpoint pen tip (with the ball directly inside the tip) was created using the writing instrument ink composition (oil-based ballpoint pen ink composition) of Example 1. As Example 25, an oil-based ballpoint pen was tested using the writing instrument ink composition of Example 1 (oil-based ballpoint pen ink composition) with a modified ballpoint pen tip (with a coil spring that directly presses the ball against the inner wall of the tip edge, and a ball with an axial movement of 7 μm). The results showed good performance in the abrasion resistance test (ball seat abrasion test), writing feel, initial writing performance test, and ink followability test, similar to Example 1.

[0070] Furthermore, in Comparative Examples 1-3, because the compound represented by the general formula (Chemical Formula 1) was not used, the abrasion resistance test (ball seat abrasion test) was poor, and the ink followability test was also inferior.

[0071] Furthermore, when using retractable writing instruments such as retractable or twist-action writing instruments, the initial writing performance is one of the important performance characteristics, so using an ink composition like that of the present invention is effective.

[0072] Furthermore, in this embodiment, a writing instrument (oil-based ballpoint pen) is exemplified in which a ballpoint pen refill containing a writing instrument ink composition (oil-based ballpoint pen ink composition) is disposed inside the barrel. However, the writing instrument (oil-based ballpoint pen) of the present invention may be a direct-fill type writing instrument (ballpoint pen) in which the barrel itself serves as the ink storage cylinder and the writing instrument ink composition (oil-based ballpoint pen ink composition) is directly stored inside the barrel, or it may be a structure in which the writing instrument (ballpoint pen refill) containing the writing instrument ink composition (oil-based ballpoint pen ink composition) inside the ink storage cylinder is used as is. [Industrial applicability]

[0073] This invention Oil-based ballpoint pen ink composition, It can be used as a writing instrument, and more specifically, as a ballpoint pen, such as a capped or retractable writing instrument, filled with the ink composition for writing instruments. 、 It can be widely used as such.

Claims

1. It comprises a coloring agent, an organic solvent, and a compound represented by the general formula (Chemical Formula 1), The organic solvent is an aromatic glycol monoether solvent. An oil-based ballpoint pen ink composition characterized by the following: 【Chemistry 1】

2. The oil-based ballpoint pen ink composition according to claim 1, characterized in that the hydroxyl value (mgKOH / g) of the general formula (Chemical Formula 1) is 100 to 1000 (mgKOH / g).

3. The oil-based ballpoint pen ink composition according to claim 1 or 2, characterized in that the oil-based ballpoint pen ink composition comprises a polyvinyl butyral resin or a ketone resin.

4. The oil-based ballpoint pen ink composition according to any one of claims 1 to 3, characterized in that the oil-based ballpoint pen ink composition comprises a nonionic surfactant.

5. The oil-based ballpoint pen ink composition according to any one of claims 1 to 4, characterized in that the oil-based ballpoint pen ink composition comprises a phosphate ester surfactant or a fatty acid.

6. 20℃, shear rate 5sec －１ An oil-based ballpoint pen ink composition according to any one of claims 1 to 5, characterized in that the ink viscosity is 30,000 mPa·s or less.

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 any one of claims 1 to 6 in the ink reservoir.

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