JP2020083927A - Ink composition for writing instrument and writing instrument using the same - Google Patents

Abstract

To produce an ink composition for a writing instrument that suppresses ink leakage from a clearance of a writing end part (ink leakage from a clearance between a ball and a tip end) and gives good writing performance at the start of writing when the writing end part dries up.SOLUTION: The ink composition for a writing instrument includes a coloring agent, an organic solvent and a fructooligosaccharide fatty acid ester.SELECTED DRAWING: None

Description

The present invention relates to a writing instrument ink composition and a writing instrument using the same.

Conventionally, in an ink composition for a writing instrument, in order to suppress ink leakage from the gap between the writing tip (ink leakage from the gap between the ball and the tip of the tip), a specific resin or shear thinning agent is added as an ink leakage inhibitor. Techniques for oil-based ink compositions and water-based ink compositions in which the ink viscosity has been set to a high level have been proposed, and ink leakage can be suppressed to some extent, but if the writing tip is left in the atmosphere, When the solvent, etc. inside evaporate and the resin, shear thinning agent (ink leakage inhibitor), colorant, etc. dry and solidify, handwriting blurring occurs in the writing (writing performance) during dry-up, There was a drawback that the writing quality was not sufficient.

In order to improve the writing (writing performance) during such dry-up, we were considering using various solvents and additives. For example, as a solvent containing a non-volatile organic solvent having a vapor pressure of 0.005 to 0.5 mmHg (20° C.) as a main solvent, JP-A-6-247093 “oil-based ballpoint pen” has an average molecular weight of 200 to Japanese Patent Application Laid-Open No. 7-196971 entitled “Ink composition for oil-based ballpoint pens” containing polyethylene glycol of 4,000,000 has a decamacadamia nut oil fatty acid decaglyceryl and an alkyl group having 16 or more carbon atoms at room temperature. And those containing at least a solid polyoxyethylene alkyl ether include those disclosed in JP-A 2008-88264, "Oil based ink composition for ballpoint pens" and JP-A-63-8465, "Aqueous pigment ink for ball pens". , JP-A-2015-67828, "Water-based ink composition for writing instruments" and the like.

"Japanese Patent Laid-Open No. 6-247093" "Japanese Patent Laid-Open No. 7-196971" "Japanese Patent Laid-Open No. 2008-88264" "JP-A-63-8465" "JP-A-2015-67828"

However, in Patent Document 1, when a non-volatile organic solvent having a vapor pressure of 0.005 to 0.5 mmHg (20° C.) is contained as the organic solvent, it is effective in preventing the ink from completely drying. The dryness was poor, and that alone was not enough to satisfy the write-out (write-out performance) during dry-up.

Further, in Patent Documents 2 and 3, polyethylene glycol having a specific molecular weight and decamadamia nut oil fatty acid decaglyceryl are contained as additives for the oil-based ink, and in Patent Document 4, wax emulsion is contained as an additive for the water-based ink. Therefore, by forming a resin film on the tip of the tip, it is possible to suppress the drying of the writing tip and suppress the thickening of the ink in the tip, thus improving the writing performance to some extent. Since the resin film is hard, writing scratches were generated during writing (writing performance) during dry-up, and sufficient writing performance was not obtained.

Further, in Patent Document 5, a resin film is formed by containing a non-reducing sugar and a decomposed product of reduced starch as an additive for an aqueous ink, but the resin film is too soft and sufficient writing performance cannot be obtained. It was

As described above, even if the ink leakage can be suppressed by forming the resin coating on the writing tip with the ink leakage inhibitor such as the specific resin or the shear thinning agent, the resin coating is hard. Therefore, the writing performance is inferior, and it is difficult to make the two performances compatible with each other, and there is room for improvement.

An object of the present invention is to obtain an ink composition for a writing instrument that suppresses ink leakage and improves writing performance, and a writing instrument using the same.

The present invention is to solve the above problems.
"1. An ink composition for a writing instrument, comprising a colorant, an organic solvent, and a fructooligosaccharide fatty acid ester.
2. Content of the said fructooligosaccharide fatty acid ester is 0.1-10.0 mass% with respect to the ink composition whole quantity, The ink composition for writing instruments of Claim 1 characterized by the above-mentioned.
3. The ink composition for a writing instrument according to item 1 or 2, wherein the ink composition for a writing instrument contains a surfactant.
4. The ink composition for a writing instrument according to any one of items 1 to 3, wherein the ink composition for a writing instrument contains a polyvinyl butyral resin or a ketone resin.
5. The ink composition for a writing instrument according to any one of items 1 to 4, wherein the ink viscosity at 5.20° C. and a shear rate of 3.4 sec ⁻¹ is 50,000 mPa·s or less.
6. A writing instrument containing the ink composition for a writing instrument according to any one of items 1 to 5.
7. A ball-point pen tip rotatably holding a ball is provided at the tip of the ink container, and the ink composition for a writing instrument according to any one of items 1 to 6 is contained in the ink container. A ball-point pen characterized by
8. A ball-point pen according to item 7, which is an oil-based ball-point pen. ".

The present invention suppresses ink leakage from the gap between the writing tip (ink leakage from the gap between the ball and the tip of the writing tip) and improves the writing performance when the writing tip is dried, and an ink composition for the same. I was able to obtain the writing instrument used.

Hereinafter, embodiments of the present invention will be described in detail. In the present specification, "parts", "%", "ratio" and the like indicating the composition are based on mass unless otherwise specified, and the content refers to a constituent component based on the mass of the ink composition. Is% by mass.

A feature of the present invention is that the ink composition for a writing instrument contains fructooligosaccharide fatty acid ester to prevent not only ink leakage from a gap between writing tips (ink leakage from a gap between a ball and a tip of a writing tip). Furthermore, it has been found that the writing performance when the writing tip is dry can be made good, and the two performances can be compatible.

(Fructooligosaccharide fatty acid ester)
In the present invention, it is important that the ink composition for a writing instrument contains a fructooligosaccharide fatty acid ester in order to more easily suppress ink leakage. This is because the fructooligosaccharide fatty acid ester is dispersed in the ink in the form of viscous particles, which causes a physical obstacle in the gap between the writing tip of the writing instrument and suppresses the flow of the ink. While suppressing ink leakage from the gap (in the case of a ballpoint pen, ink leakage from the gap between the ball and the tip of the tip), by further forming a film with high adhesiveness when the writing tip is dried, This is because ink leakage can be further suppressed from the gap. In particular, in the case of a ballpoint pen, an ink composition for an oil-based ballpoint pen that is effective in a ballpoint pen and is set to have a high ink viscosity because a gap between the ball and the tip of the tip is likely to be created by repeated writing and the influence of ink leakage is likely to occur. Then, it is more effective.
Further, when a resin or the like is used as the ink viscosity modifier, ink leakage can be suppressed by forming a resin film when the writing tip portion is dried, but a hard resin film is easily formed and Since the film formation takes time (slow drying), the ink in the chip dries, the ink thickens easily, the writing performance tends to deteriorate, and there is room for improvement.
Therefore, as a further effect of the fructooligosaccharide fatty acid ester, the fructooligosaccharide fatty acid ester is dispersed in viscous particles, and when the writing tip is dried, the film formed is a brittle particle film and does not become hard. Performance can also be improved. Therefore, by using the fructooligosaccharide fatty acid ester, it is possible not only to suppress ink leakage from the gap at the writing tip, but also to improve writing performance at the same time.
Even if a resin film is formed by using a resin as an ink viscosity adjusting agent as described later, the writing performance can be improved, which is effective.
Further, the fructooligosaccharide fatty acid ester pigment is more preferable because it also has an effect of improving the pigment dispersibility.

The fructooligosaccharide fatty acid ester is an ester of fructooligosaccharide and a fatty acid, and has a structure represented by the following chemical formula (Formula 1).
In the following chemical formula (Formula 1), n represents the number of fructose residues constituting fructo-oligosaccharide, and R represents a residue of a fatty acid forming an ester bond with a hydroxyl group of the fructose residue or hydrogen. When the polymer of fructooligosaccharide that constitutes the fructooligosaccharide fatty acid contains glucose, R′ is a glucose residue represented by the following chemical formula (Formula 1), and when the polymer of fructooligosaccharide does not contain glucose: , R'represents a residue of fatty acid similar to R or hydrogen.

The fructo-oligosaccharide is an oligosaccharide having fructose as a main component, and the average molecular weight of the fructo-oligosaccharide (hereinafter, also referred to as molecular weight) is preferably 300 to 10,000. The average molecular weight is the number average molecular weight.
The fatty acid is represented by the general formula R1COOH, and a straight chain alkyl group or at least one of a branched chain alkyl group and an alkenyl group is used for the hydrocarbon group R1 constituting the fatty acid. In view of suppressing ink leakage and improving writing performance, the number of carbon atoms contained in the alkyl group and alkenyl group is preferably 7 to 17, and more preferably 12 to 17 in consideration. It is more preferable to have a branched chain alkyl group. As the fatty acid, for example, at least one of caprylic acid, capric acid, lauric acid, 2-ethylhexanoic acid, isononanoic acid, isopalmitic acid, 2-hexyldecanoic acid, isostearic acid, and oleic acid is used. Specific examples of the fructooligosaccharide fatty acid ester include caprylic acid fructooligosaccharide, capric acid fructooligosaccharide, (capryl/capric acid) fructooligosaccharide, lauric acid fructooligosaccharide, 2-ethylhexanoic acid fructooligosaccharide, isononanoic acid fructooligosaccharide, 2-hexyldecane. Examples thereof include acid fructooligosaccharides, isostearic acid fructooligosaccharides, (lauric acid/isononanoic acid) fructooligosaccharides. In consideration of suppressing ink leakage and improving both of writing performance in a well-balanced manner, it is preferable to use 2-hexyldecanoic acid fructooligosaccharide (the following chemical formula (Formula 2)).

The content of the fructooligosaccharide fatty acid ester is preferably 0.1 to 10 mass% with respect to the total amount of the ink composition. This is because if it is less than 0.1% by mass, the writing performance tends to be affected, and if it exceeds 10.0% by mass, it is difficult to suppress ink leakage. Further, considering the above effects, 0.1 to 5.0 mass% is preferable, and further considering, 0.5 to 3.0 mass% is preferable.

(Colorant)
The colorant used in the oil-based ink composition and the aqueous ink composition used in the present invention is not particularly limited, such as dyes and pigments, and can be appropriately selected and used. You may use a dye and a pigment together.
As the oil-based ink, dyes include oil-soluble dyes, acid dyes, basic dyes, metal-containing dyes, and various salt-forming type dyes thereof, such as salt-forming dyes of acid dyes and basic dyes, and organic dyes. Examples thereof include salt-forming dyes of acids and basic dyes, and salt-forming dyes of acid dyes and organic amines. These dyes may be used alone or in combination of two or more. As the dye, it is preferable to use at least a salt-forming dye in consideration of the stability over time due to the compatibility with the components in the ink, and further consider that the stability of the salt-forming bond can maintain the stability over time. For example, it is preferable to use a salt-forming dye of a basic dye and an organic acid, a salt-forming dye of an acid dye and a basic dye, and a salt-forming dye of an acid dye and an organic amine. Salt-forming dyes of organic acids with organic acids are preferred.
Regarding the dye, specifically, Balifast Black 1802, Balifast Black 1805, Balifast Black 1807, Balifirst Violet 1701, Balifirst Violet 1704, Balifirst Violet 1705, Balifirst Blue 1601, Balifirst Blue 1605, Balifirst. Blue 1613, Bali First Blue 1621, Bali First Blue 1631, Bali First Red 1320, Bali First Red 1355, Bali First Red 1360, Bali First Yellow 1101, Bali First Yellow 1151, Nigrosine Base EXBP, Nigrosine Base EX, BASE OF BASIC DYES ROB-B, BASE OF BASIC DYES RO6G-B, BASE OF BASIC DYES VPB-B, BASE OF BASIC DYES VP-B, BASE OF BASIC DYES MVB-3 (above, manufactured by Orient Chemical Industry Co., Ltd.), Eisenspirone Black GMH-Special, Aizenspirone Violet C-RH, Aizenspirone Blue GNH, Aizenspirone Blue 2BNH, Aizenspirone Blue C-RH, Aizenspirone Red C-GH, Aizenspirone Red C-BH, Aizenspirone Yellow C-GNH, Aizen spirone yellow C-2GH, S.I. P. T. Blue 111, S.I. P. T. Blue GLSH-Special, S.I. P. T. Red 533, S.I. P. T. Orange 6, S.I. B. N. Violet 510, S.I. B. N. Yellow 530, S.I. R. C-BH (above, Hodogaya Chemical Co., Ltd. product) etc. are mentioned.

As the water-based ink, direct dyes, acid dyes, basic dyes, metal-containing dyes, various salt-forming dyes and the like can be adopted.
Regarding the dye, specifically, various dyes are commercially available, and any of them can be selected and used. Specifically, (a) direct dyes include direct yellow 4, the same 26, the same 44, the same 50, the same 85, Direct Red 1, the same 2, the same 4, the same 23, the same 31, the same 37, the same 39. , Ibid 75, ibid 80, ibid 81, ibid 83, ibid 225, ibid 226, ibid 227, direct blue 1, ibid 3, ibid 15, ibid 41, ibid 71, ibid 86, ibid 106, ibid 119 and direct orange 6 Etc. (b) Acid dyes include Acid Black 1, 2, 2, 24, 26, 31, 31, 52, 107, Acid Orange 56, Acid Yellow 3, 7, 7, 17, 19, and the like. 23, 42, 49, 61, 92, Acid Red 8, 9, 9, 14, 18, 18, 51, 52, 73, 87, 92, 94, Acid Blue 1, the same 7, the same 9, the same 22, the same 62, the same 90, the same 103, the acid greens 3, the same 9, the same 16, the same 25, the same 27, the acid violet 15, the same 17 and the like (c) as a basic dye, C. I. Basic Yellow-1, 2, 21, 21, 7, 40, C.I. I. Basic Orange 2, the same 14, the same 32, C.I. I Basic Red 1, the same 1:1, the same 2, the same 9, the same 14, C.I. I. Basic Violet 1, Same 3, Same 7, Same 10, Same 11:1, C.I. I. Basic Bull-3, Same as 26, Same as 26, Basic Green 4, C.I. I. Basic Brown 12, C.I. I. (D) Other dyes such as Basic Black 2, Methyl Violet, Victoria Blue FB, Malachite Green, Rhodamine series, and the like include disperse dyes such as Dispers Yellow 82, 121, and Dispers Blue 7.

Examples of the pigment include inorganic, organic and processed pigments. Specifically, carbon black, aniline black, ultramarine blue, yellow lead, titanium oxide, iron oxide, phthalocyanine, azo, quinacridone, diketo. Examples include pyrrolopyrrole-based, quinophthalone-based, slene-based, triphenylmethane-based, perinone-based, perylene-based, dioxazine-based, metallic pigments, pearl pigments, fluorescent pigments, and phosphorescent pigments.

It is preferable to use a pigment as the colorant. By using pigment particles, in the case of a ball-point pen, a physical obstacle is caused in the gap between the ball and the inner wall of the tip of the tip, and ink leakage is suppressed. This is because it is easy to do. Further, in the present invention, by using the polyvinyl butyral resin or the fructooligosaccharide fatty acid ester, the polyvinyl butyral resin, the fructooligosaccharide fatty acid ester, and the pigment are used to form a film on the writing tip portion and physically It is preferable that a synergistic action works due to the obstacle because a higher ink leakage suppressing effect can be obtained, and at the same time a pigment dispersing effect can be obtained. In addition, pigments are preferable because they are excellent in handwriting fastness and particularly excellent in light resistance.

The content of the colorant is preferably 1 to 45 mass% with respect to the total amount of the ink composition. This is because if it is less than 1% by mass, dark handwriting tends to be difficult to obtain, and if it exceeds 45% by mass, it tends to affect the dissolution stability of the dye and the dispersion stability of the pigment. Is preferably 3 to 35 mass %, and further considered is 3 to 30 mass %.

(Organic solvent)
As the organic solvent used in the present invention, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol dimethyl ether, ethylene glycol monophenyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, diethylene glycol dimethyl ether, 3 -Glycol ether solvent such as methoxybutanol and 3-methoxy-3-methylbutanol, diethylene glycol, triethylene glycol, polyethylene glycol, propylene glycol, dipropylene glycol, butylene glycol, ethylene glycol, diethylene glycol, glycol solvent such as glycerin, benzyl alcohol , Methanol, ethanol, 1-propanol, 2-propanol, isopropanol, isobutanol, t-butanol, propanol alcohol, allyl alcohol, 3-methyl-1-butyn-3-ol, ethylene glycol monomethyl ether acetate and other Examples include organic solvents that are generally used as oil-based ink compositions and water-based ink compositions, such as alcohol solvents such as higher alcohols.

Among these organic solvents, considering the dispersibility in the ink with fructooligosaccharide fatty acid ester, it is preferable to use a water-insoluble organic solvent to obtain an oil-based ink composition, and among them, a glycol ether solvent is used. It is preferable to use. This is because when a glycol ether solvent is used, it is easy to absorb moisture, so that the strength of the film formed when the tip of the tip is dried is softened, and the writing performance is also improved, and when used in combination with the fructooligosaccharide fatty acid ester. It is preferable to use an aromatic glycol ether solvent in view of its effectiveness and stability in ink. Further, as the organic solvent other than the glycol ether solvent, it is preferable to use an alcohol solvent, but this is because the alcohol solvent volatilizes and the tip is easily dried, and ink leaks from the gap at the writing tip. (In the case of a ball-point pen, this is preferable because it suppresses ink leakage from the gap between the ball and the tip of the chip) and improves the ink leakage suppression performance.

Further, the content of the organic solvent is preferably 10.0 to 90.0 mass% with respect to the total amount of the ink composition in consideration of improving solubility, handwriting drying property, bleeding, etc., and drying at the tip of the tip In consideration of the property, 20.0 to 90.0 mass% is preferable, and 40.0 to 70.0 mass% is more preferable.

(Surfactant)
In the present invention, it is preferable to use a surfactant in consideration of the above-mentioned lubricity and the improvement of the writing performance when the tip portion of the tip is dried while being left in the atmosphere. .. This is because, when a surfactant is used, the coating formed by the fructooligosaccharide fatty acid ester tends to be brittle, and the writing performance can be improved and the lubricity can be improved. Examples of the surfactant include fatty acids, fatty acid esters, silicone-based surfactants, fluorine-based surfactants and phosphoric acid ester-based surfactants. Among them, considering the above effects, it is preferable to use one or more kinds among fatty acids, silicone-based surfactants, and phosphoric acid ester-based surfactants. Considering writing performance and lubricity, phosphoric acid ester is used. It is preferable to use a system surfactant. In particular, when used in a ballpoint pen, the phosphoric acid group is preferable because it adsorbs metal.
Further, as will be described later, it is preferable to use polyvinyl butyral because the ink layer formed of polyvinyl butyral and the lubricating layer of the above-mentioned surfactant can more easily improve the lubricity.

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

Specific examples of the surfactant include fatty acids such as oleic acid, stearic acid, and linoleic acid, and examples of the silicone-based surfactant include dimethyl silicone, methylphenyl silicone, polyether-modified silicone, and higher grade. Examples thereof include fatty acid ester-modified silicone, and as the fluorine-based surfactant, perfluoro group butyl sulfonate, perfluoro group-containing carboxylate, perfluoro group-containing phosphate ester, perfluoro group-containing phosphate ester type compound things, perfluoroalkyl betaine, and perfluoroalkyl amine oxide compound, and examples of the phosphoric acid ester surfactant, alkoxyethyl group _{(C n H 2n + 1 OCH} 2 CH 2 O) or alkoxy group _{(C m H 2m + 1} O) having phosphoric acid ester, phosphoric acid monoester of polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether, phosphoric acid diester of polyoxyethylene alkyl ether or polyoxyethylene alkyl aryl ether, polyoxyethylene alkyl ether or polyoxyethylene alkyl ether Examples thereof include phosphoric acid triesters of oxyethylene alkylaryl ethers, alkyl phosphoric acid esters, alkyl ether phosphoric acid esters and derivatives thereof.

The content of the surfactant is more preferably 0.1 to 5.0 mass% based on the total mass of the ink composition. This is because if it is less than 0.1% by mass, the desired lubricity tends to be difficult to obtain, and if it exceeds 5.0% by mass, the ink tends to become unstable over time. In consideration of the above, 0.3 to 3.0 mass% is preferable based on the total mass of the ink composition, and more consideration is 0.5 to 3.0 mass%.

(Amine)
In the present invention, considering the stability of the ink components in the ink and adjusting the pH, it is preferable to use an amine. Amines having ethylene oxide such as oxyethylene alkylamine and polyoxyethylene alkylamine; alkylamines such as laurylamine and stearylamine; dimethylalkylamines such as distearylamine, dimethyllaurylamine, dimethylstearylamine, dimethyloctylamine, etc. Alkanolamines such as aliphatic amines, monoethanolamine, diethanolamine, triethanolamine, dimethylethanolamine, N-methylethanolamine, N-methyldiethanolamine, diisopropanolamine, etc., among which are stable in ink. Considering the properties, amines having ethylene oxide, dimethylalkylamines, and alkanolamines are preferable. In particular, when a phosphoric acid ester-based surfactant is used, it is preferable because the effect of improving the writing performance and the writing quality can be easily obtained by stabilizing in the ink by neutralizing.

Among the amines, organic amines are preferable in consideration of stability in ink, and primary amines have the highest reactivity with other components in the ink, followed by secondary amines and tertiary amines. Since the reactivity becomes small, it is preferable to use a secondary amine or a tertiary amine in consideration of the ink stability over time. You may use these individually or in mixture of 2 or more types.

The content of the amine is preferably 0.1 to 10.0% by mass with respect to the total amount of the ink composition in consideration of the stability with the salt-forming dye and other components. Considering the neutralization with respect to the system surfactant, 0.1 to 5.0 mass% is preferable.

(resin)
Further, in order to further improve ink leakage suppression, it is preferable to use a resin as an ink viscosity modifier, as the resin, polyvinyl butyral resin, ketone resin, polyacetal resin, polyvinyl alcohol resin, cellulose resin, terpene resin, Examples thereof include alkyd resins, phenoxy resins, and polyvinyl acetate resins. Among them, it is preferable to include a polyvinyl butyral resin or a ketone resin in order to more easily improve the ink leakage suppression effect.

With regard to the polyvinyl butyral resin, it is preferable to use the polyvinyl butyral resin because it is easy to improve both the ink leakage suppression effect and the writing quality at the same time. When polyvinyl butyral resin and fructooligosaccharide fatty acid ester are used in combination, fructooligosaccharide fatty acid ester prevents the ink from flowing out from the gap between the writing tips by suppressing the flow of ink, while the writing tip is polyvinyl The butyral resin is more effective because it has an action of forming a film of a butyral resin faster, and the formed film is a film having a viscosity so that it does not become hard and the writing performance is not easily impaired. Further, in the case of a ball-point pen, the polyvinyl butyral resin always forms an ink layer having elasticity between the ball and the ball seat and makes it difficult to make direct contact with the ink layer, so that it is possible to improve the writing feel. .. Further, when a pigment is used as the colorant, a polyvinyl butyral resin is preferably used because a pigment dispersing effect can be obtained.
Here, the polyvinyl butyral resin is obtained by reacting polyvinyl alcohol (PVA) with butyraldehyde (BA), and has a structure having a butyral group, an acetyl group, and a hydroxyl group.
In particular, when the ball diameter is set to be 1.0 mm to 2.0 mm larger than usual, the influence of ink leakage is likely to occur from the gap between the ball-point pen tip body and the ball, and therefore polyvinyl butyral resin is effective. It is more effective when the fructooligosaccharide fatty acid ester used in the present invention and the polyvinyl butyral resin are used in combination, and particularly when 1.2 mm to 2.0 mm is used.

The polyvinyl butyral resin preferably has a hydroxyl group content of 25 mol% or more. This is because a polyvinyl butyral resin having a hydroxyl group amount of less than 25 mol does not have sufficient solubility in an organic solvent, and it is difficult to obtain a sufficient lubrication effect and an ink leakage suppression effect. Further, considering the writing performance due to hygroscopicity, This is because it is preferable to use a polyvinyl butyral resin having a hydroxyl group amount of 25 mol% or more. Further, the polyvinyl butyral resin having a hydroxyl group amount of 30 mol% or more is preferable because the writing feeling is easily improved. This is because at the time of writing, frictional heat is generated by the rotation of the ball, the ink at the tip of the tip is warmed and the temperature of the ink rises, but the polyvinyl butyral resin is different from other resins, Even if the ink temperature rises, it has the property of making it difficult to lower the ink viscosity.By forming an ink layer that is always elastic between the ball and the ball seat, making it hard to make direct contact, the writing feel is improved. Tends to be easy. In particular, the oil-based ball-point pen is effective because the oil-based ball-point pen often writes with a high writing pressure. When a polyvinyl butyral resin having a hydroxyl group content of more than 40 mol% is used, the amount of moisture absorption tends to increase, and the temporal stability with the oil-based ink component is likely to be affected. Therefore, a polyvinyl butyral resin having a hydroxyl group content of 40 mol% or less is preferred. Therefore, a polyvinyl butyral resin having a hydroxyl group amount of 30 to 40 mol% is preferable, and a hydroxyl group amount of 30 to 36 mol% is more preferable.
In addition, the amount of hydroxyl groups (mol %) of the polyvinyl butyral resin means the content of hydroxyl groups (mol %) with respect to the total amount of butyral groups (mol %), acetyl groups (mol %), and hydroxyl groups (mol %). It shows the rate.

Regarding the average degree of polymerization of the polyvinyl butyral resin, when the average degree of polymerization is 200 or more, the ink leakage suppression performance is easily improved, and when the average degree of polymerization exceeds 2500, the ink viscosity becomes too high. Therefore, the average polymerization degree is preferably 200 to 2500. Further, considering the effects of suppressing ink leakage and crying bloating, the average degree of polymerization is preferably 1500 or less. Furthermore, when further considered, the average degree of polymerization is preferably 250 to 1000, more preferably 250 to 700. Here, the average degree of polymerization refers to the number of basic units constituting one molecule of the polyvinyl butyral resin, and a value measured based on the method specified in JISK6728 (2001 version) can be adopted. ..

Regarding the polyvinyl butyral resin, specifically, trade name of Sekisui Chemical Co., Ltd.; S-REC BH-3 (amount of hydroxyl group: 34 mol%, average degree of polymerization: 1700), BH-6 (amount of hydroxyl group: 30 mol%) , Average degree of polymerization: 1300), BX-1 (hydroxyl group amount: 33±3 mol%, average degree of polymerization: 1700), same BX-5 (hydroxyl group amount: 33±3 mol%, average degree of polymerization: 2400), same BM -1 (hydroxyl group amount: 34 mol%, average polymerization degree: 650), BM-2 (hydroxyl group amount: 31 mol%, average polymerization degree: 800), BM-5 (hydroxyl group amount: 34 mol%, average polymerization degree: 850) ), the same BL-1 (hydroxyl group amount: 36 mol%, average degree of polymerization: 300), the same BL-1H (hydroxyl group amount: 30 mol%), the same BL-2 (hydroxyl group amount: 36 mol%, average degree of polymerization: 450), The same BL-2H (hydroxyl group amount: 29 mol%), the same BL-10 (hydroxyl group amount: 28 mol%) and the like, a trade name of Kuraray Co., Ltd.; Mobital B20H (hydroxyl group amount: 26 to 31 mol%, average degree of polymerization: 250-500), B30T (hydroxyl group amount: 33-38 mol%, average degree of polymerization: 400-650), B30H (hydroxyl group amount: 26-31 mol%, average degree of polymerization: 400-650), B30HH (hydroxyl group amount). : 30 to 34 mol%, average degree of polymerization: 400 to 650), B45H (hydroxyl group amount: 26 to 31 mol%, average degree of polymerization: 600 to 850), B60T (hydroxyl group amount: 34 to 38 mol%, average degree of polymerization: 750 to 1000), the same B60H (hydroxyl group amount: 26 to 31 mol%, average degree of polymerization: 750 to 1000), the same B75H (hydroxyl group amount: 26 to 31 mol%, average degree of polymerization: 1500 to 1750) and the like. You may use these individually or in mixture of 2 or more types.

It is preferable to use a ketone resin in combination with a fructooligosaccharide fatty acid ester because a higher effect of suppressing ink leakage can be expected synergistically.

If the total content of the resin is less than 1.0% by mass with respect to the total amount of the ink composition, the amount of resin film formed may be insufficient, and the ink leakage suppression performance tends to be poor, and exceeds 40.0% by mass. Since the solubility in the ink tends to be poor, 1.0 to 40.0 mass% is preferable with respect to the total amount of the ink composition. Further, considering the ink leakage suppression performance, 5.0% by mass or more is preferable, and if it exceeds 30.0% by mass, the ink viscosity tends to be too high and the writing quality and the writing performance tend to be affected. 0-30.0 mass% is preferable.

The ink viscosity of the oil-based ink composition for a writing instrument of the present invention is not particularly limited, but the ink viscosity at 20° C. and a shear rate of 3.4 sec ⁻¹ (at rest) is 300 to 5000 mPa·s. Is preferred. This is because even when the viscosity of the low viscosity ink is 300 mPa·s, the fructooligosaccharide fatty acid ester is dispersed in the ink in the form of viscous particles, which causes a physical obstacle in the gap at the writing tip of the writing instrument, Since it is easy to suppress ink leakage from the gap between the writing tip (in the case of a ballpoint pen, ink leakage from the gap between the ball and tip of the ball), it is preferable that the flow rate be 300 mPa·s or more. Considering that the taste tends to be good, it is preferably 5000 mPa·s or less. Further, in consideration of suppression of ink leakage and easy improvement of writing quality in a well-balanced manner, the ink viscosity is preferably 500 to 3000 mPa·s, and further considering, the ink viscosity is 500 to 1500 mPas. -S is preferable.

The ink viscosity of the aqueous ink composition for a writing instrument is not particularly limited, but if the ink viscosity at 20° C. and a shear rate of 1.92 sec ⁻¹ (at rest) exceeds 5000 mPa·s, the writing performance, The ink viscosity at 20° C. and a shear rate of 1.92 sec ⁻¹ (at rest) is preferably 5000 mPa·s or less, more preferably 4000 mPa·s or less, because the writing quality and the ink following performance are easily deteriorated. Preferably. Further, by setting the ink viscosity at 20° C. and a shear rate of 1.92 sec ⁻¹ (at rest) to 1000 mPa·s or more, ink leakage at the writing tip (ink leakage from the gap between the ball and the tip of the writing tip) is suppressed. Since it is easy, the ink viscosity is preferably 1000 to 4000 mPa·s. Further, the ink viscosity is more preferably 1200 to 3500 mPa·s, considering that the writing performance and writing quality are further improved.

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

The ink composition for a writing instrument according to the present invention can be produced by any conventionally known method. Specifically, it can be produced by mixing the above-mentioned respective components in necessary amounts and mixing them with various agitators such as propeller agitation, homodisper, or homomixer, and various dispersers such as a bead mill.

(Writing instrument)
The ink composition for a writing instrument of the present invention can be used for a writing instrument such as a marking pen or a ballpoint pen having a pen tip such as a fiber tip, a felt tip, a plastic tip or a ballpoint pen tip. Among them, the pen core is preferably a fiber tip or a felt tip in order to improve the writability on a non-permeable recording medium such as a film. Particularly, it is preferably used for a marking pen. The porosity of the pen core is preferably 50% to 80%. When the porosity of the pen core is within the above numerical range, the pigment particles are not clogged and an appropriate ink discharge amount can be maintained.

The writing instrument of the present invention may be configured to directly fill the ink composition for a writing instrument, or may be provided with an ink container or an ink occlusion body that can be filled with the oil-based ink composition. .. Further, in order to redisperse the pigment particles and the like, it is preferable that the ink container contains a stirring body such as a stirring ball for stirring the ink. Furthermore, examples of the shape of the stirring body include a spherical body and a rod-shaped body. The material of the stirrer is not particularly limited, but specific examples thereof include metals, ceramics, resins, glass, and the like. Among these, the stirring force for redispersing the pigment particles and the like is considered. If so, it is preferable to use a metal material, and from the viewpoint of cost, it is preferable to use a glass material. The agitator may be made of a plurality of materials.

The retracting mechanism of the writing instrument of the present invention is not particularly limited, and examples thereof include a cap type having a cap that covers the pen tip, a knock type, a rotary type, and a slide type. Further, a retractable type in which the pen tip can be housed in the barrel may be used.

Further, the ink supply mechanism in the writing instrument is not particularly limited, and, for example, (1) a mechanism that includes an ink guide core made of a fiber bundle or the like as an ink flow rate adjusting member and supplies the ink composition to the pen tip, 2) A comb groove-shaped ink flow rate adjusting member is provided, and a mechanism for supplying the ink composition to the pen tip with the interposition thereof, and (3) An ink flow rate adjusting member by a valve mechanism for supplying the ink composition to the pen tip. And (4) a mechanism for directly supplying the ink composition to the pen tip from the ink container or the barrel including the pen tip.

In one embodiment, the writing instrument is a marking pen, and the pen tip is not particularly limited and may be, for example, a fiber tip, a felt tip, a plastic tip, or the like, and the shape thereof is a bullet shape, a chisel shape, or a It may be a brush pen type or the like.

In one embodiment, the writing instrument is a ball-point pen, and preferably a ball-point pen having an ink backflow preventer.

(Ballpoint pen tip)
The amount of movement of the ball of the ballpoint pen tip used in the present invention in the direction of the vertical axis is not particularly limited, but is preferably 3 to 50 μm. This is because if it is less than 3 μm, it becomes difficult to obtain dark handwriting and good writing quality, and if it exceeds 50 μm, ink leakage performance and writing performance tend to be affected. The thickness is preferably 5 to 40 μm.

As in the present invention, in order to suppress both ink leakage and to improve both writing performance, a ball rotatably held at the tip of a ballpoint pen tip is directly or via a pressing body by an elastic member such as a coil spring. It is equipped with a valve mechanism that presses against the inner wall of the tip edge of the tip and causes a gap between the inner wall of the tip edge of the tip and the ball to flow out ink by the pressing force during writing, and closes the minute gap at the tip end when not in use. Preferably.

In addition, the material used for the balls is not particularly limited, but a cemented carbide ball containing tungsten carbide as a main component, a metal ball such as stainless steel, and a ceramic such as silicon carbide, silicon nitride, alumina, silica, and zirconia. Examples include balls and ruby balls.
The diameter of the ball is not particularly limited, but if the diameter of the ball is large, ink leaks easily from the gap between the ballpoint pen tip body and the ball, and the writing performance tends to be poor when the writing tip is dried. When it is made larger than usual and is 1.0 mm to 2.0 mm, the influence is likely to occur, and particularly when it is 1.2 mm to 2.0 mm, it is remarkable and more effective.

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

Example 1 (oil-based ink formulation)
The ink composition for an oil-based ballpoint pen of Example 1 was prepared by adding a pigment and a polyvinyl butyral resin (pigment dispersant) to an organic solvent and dispersing them with a disperser, and then using a dye as the colorant and the pigment dispersion, and benzyl as the organic solvent. Alcohol, ethylene glycol monophenyl ether, fructooligosaccharide fatty acid ester, polyvinyl butyral resin as the resin, phosphate ester-based surfactant as the surfactant, polyvinylpyrrolidone are adopted, and a predetermined amount thereof is weighed to 60°C. After heating, it was completely dissolved using a Disper stirrer to obtain an oil-based ink composition for a ballpoint pen. The specific compounding amount is as follows. When the ink viscosity of Example 1 was measured using a viscometer RVDVII+Pro CP-52 spindle manufactured by Brookfield Co., Ltd., a shear rate of 3.4 sec ⁻¹ and an ink viscosity of 3000 mPa under an environment of 20° C.・It was s.

Example 1
Colorant (dye, red salt forming dye of basic dye and organic amine) 8.0% by mass
Coloring agent (dye, blue salt forming dye of basic dye and organic amine) 8.0% by mass
Coloring agent (dye, salt forming dye of acid dye and amine) 8.0% by mass
Coloring agent (carbon black) 5.0% by mass
Organic solvent (benzyl alcohol) 50.0% by mass
Organic solvent (ethylene glycol monophenyl ether) 10.0% by mass
Fructooligosaccharide fatty acid ester (Chemical Formula 2) 1.0% by mass
Surfactant (phosphate ester type surfactant) 2.0% by mass
Polyvinyl butyral resin (hydroxyl group amount: 36 mol%, average degree of polymerization: 300) 7.5 mass%
Polyvinylpyrrolidone resin 0.5% by mass

Examples 2-12
As shown in Table 1, the ink compositions for oil-based ballpoint pens of Examples 2 to 12 were obtained in the same procedure as in Example 1 except that the ink components were changed. The evaluation results are shown in the table.
The ink viscosity of Example 6 was measured using a viscometer RVDV II+Pro CP-52 spindle manufactured by Brookfield Co., Ltd., a shear rate of 3.4 sec ⁻¹ and an ink viscosity of 20° C. were measured. =500 mPa·s.

Comparative Examples 1 to 4
As shown in the table, the ink compositions for oil-based ballpoint pens of Comparative Examples 1 to 4 were obtained by the same procedure as in Example 1 except that the ink components and the chip specifications were changed. The evaluation results are shown in the table.

Test and Evaluation The ink compositions for oil-based ballpoint pens prepared in Examples 1 to 12 and Comparative Examples 1 to 4 were rotatably held by a ball (φ 0.7 mm) at the tip of an ink container. A ball spring having a coil spring that directly presses the ball against the inner wall of the tip of the tip is attached to the inner wall of the chip. ) Is directly housed and the ballpoint refill is placed in an oil-based ballpoint pen (trade name: Supergrip) manufactured by Pilot Corporation, and an oil-based ballpoint pen is produced, and a writing paper JIS P3201 is used as a writing test paper. Tests and evaluations were performed.

Example 13 (water-based ink formulation)
The aqueous ball-point pen ink composition of Example 13 was prepared by using a pigment dispersion as a colorant, water, a polyhydric alcohol as a water-soluble organic solvent, triethanolamine as an amine, a phosphate ester surfactant as a lubricant, and a rust preventive agent. The agent was used, a predetermined amount of the agent was weighed, heated to 60° C., and then completely dissolved using a Disper stirrer to prepare a base ink. Thereafter, while heating the above-prepared base ink, a fructooligosaccharide fatty acid ester and a shear thinning viscosity imparting agent were added, and the mixture was sufficiently mixed and stirred using a homogenizer stirrer until a uniform state was obtained. An ink composition for a ballpoint pen was obtained.
The ink viscosity of Example 13 was measured with a Brookfield DV-II viscometer (CPE-42 rotor) under a 20° C. environment at a shear rate of 1.92 sec ⁻¹ (rotation speed 0.5 rpm). When the ink viscosity was measured under the conditions, it was 1800 mPa·s.

Next, the present invention will be described with reference to examples.
Pigment dispersion (colored resin particles, solid content 34%) 20.0 parts by mass
66.0 parts by weight of water
Polyhydric alcohol (glycerin) 10.0 parts by mass
0.5 parts by mass of fructooligosaccharide fatty acid ester (Chemical formula 2)
Amine (triethanolamine) 2.0 parts by mass
Lubricant (phosphate ester type surfactant) 1.0 part by mass
Antirust agent (benzotriazole) 0.5 parts by mass
Shear thinning agent (xanthan gum) 0.4 parts by mass

Except for changing the content of fructooligosaccharide fatty acid ester from the ink components of Examples 14 and 15 to 1.0 parts by mass and 3.0 parts by mass, respectively, the same procedure as in Example 13 was repeated. An aqueous ink composition for a ballpoint pen was obtained.

Comparative Example 5
An aqueous ink composition for a ballpoint pen of Comparative Example 5 was obtained in the same procedure as in Example 13, except that the fructooligosaccharide fatty acid ester was removed from the ink component of Example 13.

Test and Evaluation The ink compositions for water-based ballpoint pens prepared in Examples 13 to 15 and Comparative Example 5 were rotatably held with a ball (φ0.7 mm) at the tip of an ink container. A ball spring having a coil spring pressed directly against the inner wall of the tip edge of the chip is mounted with a movement amount of the ball in the longitudinal direction of 30 μm), and the ink for water-based ballpoint pens of Example 15 and Comparative Example 5 (1 0.0 g) was directly stored and the ballpoint refill was placed in a water-based ballpoint pen (trade name: G-2) manufactured by Pilot Corporation to prepare a water-based ballpoint pen, and writing paper JIS P3201 was used as a writing test paper. The following tests and evaluations were performed.

Ink leakage suppression test: The ink was leaked from the tip of the tip by leaving the pen tip facing downward for 7 days in an environment of 30° C. and 85% RH.
There is no ink drop on the tip of the tip ・・・◎
Ink droplets at the tip of the tip are within 1/4 of the taper portion.
Ink droplets at the tip of the tip are 1/4 or more and 1/2 or less of the taper portion.
Ink droplets at the tip of the tip are 1/2 or more of the taper portion... ×

Writing performance test: After writing by handwriting, leave the tip of the tip for 24 hours in an environment of 20°C and 65% RH, and then write in the running test under the following writing conditions. Was measured.
<Writing Conditions> Under the conditions of a writing load of 200 gf, a writing angle of 70°, and a writing speed of 4 m/min, a straight line was drawn by a running tester and evaluated.
The length of handwriting blur is less than 15 mm.
The length of brush strokes is 15 mm or more and less than 20 mm...
The length of the brush stroke is 20 mm or more and less than 40 mm... △
Brush strokes with a length of 40 mm or more... ×

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

In Examples 1 to 15, good performances were obtained in the ink leakage suppression test, the writing performance, and the writing taste.
In addition, when the ink using the pigment as the colorant in Examples 1 to 15 was observed with a microscope, the pigment dispersibility was good, and no precipitate was found.

In Comparative Examples 1 and 5, since fructooligosaccharide fatty acid ester was not used, and in Comparative Example 2, sucrose fatty acid ester was used, the ink leakage suppression performance and the writing performance were inferior.

In Comparative Examples 3 and 4, when oligosaccharides were added, they were not uniformly dispersed and could not be made into ink.

In addition, when using a retractable writing instrument (retractable ballpoint pen) such as a knock-type writing instrument or a rotary feeding type writing instrument, the ink leakage suppression performance and the writing performance are one of the most important performances. It is effective to use an oil-based ballpoint pen such as the present invention that can suppress ink leakage from the gap between the writing tip (ink leakage from the gap between the ball and the tip) and improve the writing performance. Is.

Further, in the present example, an oil-based ballpoint pen having a ball-point pen refill containing the ink composition for an oil-based ballpoint pen in the ink containing cylinder is provided in the barrel, and the like. It may be a direct-packing type oil-based ballpoint pen in which the ink composition for the oil-based ballpoint pen is directly stored in the shaft cylinder as the ink storage cylinder, and the ink composition for the oil-based ballpoint pen is stored in the ink storage cylinder (ballpoint pen. The refill) may be used as it is as a ballpoint pen.

INDUSTRIAL APPLICABILITY The present invention can be used as a writing instrument such as a ballpoint pen, a marking pen, a fountain pen, and a plate pen, and more specifically, can be widely used as an oil-based writing instrument such as a cap type and a retractable type, and an aqueous writing instrument.

Claims (8)

An ink composition for a writing instrument comprising a colorant, an organic solvent and a fructooligosaccharide fatty acid ester. The ink composition for a writing instrument according to claim 1, wherein the content of the fructooligosaccharide fatty acid ester is 0.1 to 10.0 mass% with respect to the total amount of the ink composition. The ink composition for a writing instrument according to claim 1 or 2, wherein the ink composition for a writing instrument contains a surfactant. The ink composition for a writing instrument according to any one of claims 1 to 3, wherein the ink composition for a writing instrument comprises a polyvinyl butyral resin or a ketone resin. The ink composition for a writing instrument according to any one of claims 1 to 4, wherein an ink viscosity at 20°C and a shear rate of 3.4 sec ^-1 is 50,000 mPa·s or less. A writing instrument containing the ink composition for a writing instrument according to any one of claims 1 to 5. A ball-point pen tip that rotatably holds a ball is provided at the tip of the ink container, and the ink composition for a writing instrument according to any one of claims 1 to 6 is housed in the ink container. A ballpoint pen that is characterized by. A ball-point pen according to claim 7, which is an oil-based ball-point pen.