JP2022171312A - Water-based ink composition for ballpoints and ballpoint storing the same - Google Patents

Abstract

To provide a water-based ink composition for ballpoints that improves ink dischargeability from a pen tip and allows for clear handwriting with reduced blurring and line skipping over the long term, and a ballpoint storing the same.SOLUTION: A water-based ink composition for ballpoints is stored in a ballpoint having a metal ballpoint chip, the ink composition comprising a colorant, a phosphate surfactant, a substance represented by formula (1) and/or a salt thereof, and water, where X and Y each denote a functional group selected from -H, -R, -OH, -OR, -NH2, -NHR and -NR2, and R is an alkyl group, excluding the case where both of X and Y are hydrogen.SELECTED DRAWING: None

Description

TECHNICAL FIELD The present invention relates to a water-based ink composition for ball-point pens.

Ballpoint pens with a metal ballpoint tip have been studied to improve the ink ejection from the pen tip and to form clear handwriting without faint or broken lines. A method of adding a lubricant such as a surfactant to smoothly rotate the ball is widely used. However, since it is not easy to maintain good ink ejection even when such additives are used, further studies are being conducted. (For example, see Patent Document 1)

Patent Document 1 describes an aqueous ink composition using crosslinked poly-N-vinylcarboxylic acid amide or crosslinked polyacrylic acid or a salt thereof and alkylbenzenesulfonic acid. This ink exhibits good ink ejection due to smooth ball rotation, and can suppress faint handwriting and broken lines.

However, even with the conventional inks, it is not easy to sustain good ink ejection, and there is room for improvement because the ink ejection properties may deteriorate over time.

Japanese Patent Application Laid-Open No. 2003-73605

The present invention is an ink contained in a ball-point pen having a ball-point pen tip made of metal, which continuously exhibits good ink ejection properties from the pen tip, and produces clear handwriting with suppressed handwriting faintness and broken lines. An object of the present invention is to provide a water-based ink composition for ball-point pens that can be formed over a long period of time and a ball-point pen containing the same.

式中、ＸとＹは－Ｈ、－Ｒ、－ＯＨ、－ＯＲ、－ＮＨ_２、－ＮＨＲおよび－ＮＲ_２から選ばれる官能基であり、Ｒはアルキル基である。ただし、Ｘ、Ｙ双方が水素である場合を除く。
２. 前記ＸとＹは、－Ｈ、－ＯＨおよび－ＮＨ_２から選ばれる官能基である（ただし、Ｘ、Ｙ双方が水素である場合を除く）、第１項に記載の水性インキ組成物。
３．インキ組成物全質量に対して、前記リン酸エステル系界面活性剤の含有量が０．１～３質量％であり、式（１）に示される物質及び／又はその塩の含有量が０．０５～２質量％である、第１項または第２項に記載の水性インキ組成物。
４．リン酸エステル系界面活性剤の含有量Ａと、式（１）に示される物質及び／又はその塩の含有量Ｂとの関係が、０．０１≦Ｂ／Ａ≦１を満たす、第１項～第３項のいずれか１項に記載の水性インキ組成物。
５．前記着色材が染料である。第１項～第４項に記載の水性インキ組成物。
６．前記染料の含有量が、水性インキ組成物全質量を基準として２質量％以下である、第５項に記載の水性インキ組成物。
７．ナフタレンスルホン酸のホルマリン縮合物を含む、第１項～第６項のいずれか１項に記載の水性インキ組成物。
８．金属製のボールペンチップを備え、第１項～第７項のいずれか１項に記載の水性インキ組成物が収容されてなるボールペン。
９．多数の円盤体が櫛溝状の間隔を開け並列配置され、前記円盤体を軸方向に縦貫するスリット状のインキ誘導溝及び該溝より太幅の通気溝が設けられ、軸心にインキ貯蔵部からペン先へインキを誘導するためのインキ誘導芯が配置されてなるペン芯を備えてなる、第８項に記載のボールペン。」とする。 "1. Ink contained in a ball-point pen having a metal ball-point pen tip, comprising a coloring agent, a phosphate surfactant, and a substance represented by the following formula (1) and/or a salt thereof , an aqueous ink composition for ballpoint pens containing water.

wherein X and Y are functional groups selected from -H, -R, -OH, -OR, -NH ₂ , -NHR and -NR ₂ , and R is an alkyl group. However, the case where both X and Y are hydrogen is excluded.
2. The water-based ink composition according to item 1, wherein X and Y are functional groups selected from —H, —OH and —NH ₂ (except when both X and Y are hydrogen). .
3. Based on the total weight of the ink composition, the content of the phosphate ester surfactant is 0.1 to 3% by mass, and the content of the substance represented by formula (1) and/or a salt thereof is 0.1% by mass. 3. The water-based ink composition according to item 1 or 2, which is 05 to 2% by mass.
4. Item 1, wherein the relationship between the content A of the phosphate ester surfactant and the content B of the substance represented by formula (1) and/or its salt satisfies 0.01 ≤ B/A ≤ 1 The water-based ink composition according to any one of items 1 to 3.
5. The coloring material is a dye. The water-based ink composition according to items 1 to 4.
6. 6. The water-based ink composition according to Item 5, wherein the content of the dye is 2% by mass or less based on the total mass of the water-based ink composition.
7. 7. The aqueous ink composition according to any one of items 1 to 6, comprising a formalin condensate of naphthalenesulfonic acid.
8. A ball-point pen comprising a metal ball-point pen tip and containing the water-based ink composition according to any one of items 1 to 7.
9. A large number of discs are arranged in parallel with a comb groove-like interval, slit-like ink guide grooves running through the discs in the axial direction and ventilation grooves wider than the grooves are provided, and an ink reservoir is provided at the center of the shaft. 9. A ball-point pen according to claim 8, comprising a pen core in which an ink guiding core is arranged for guiding ink from the pen to the nib. ”.

According to the present invention, the ink contained in a ball-point pen having a ball-point pen tip made of metal continuously exhibits good ink ejection properties from the pen tip, and provides clear ink with suppressed handwriting faintness and broken lines. Provided are a water-based ink composition for a ball-point pen, which enables handwriting to be formed over a long period of time, and a ball-point pen containing the same.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail. In the present specification, "parts", "%", "ratios" and the like that indicate compounding are based on mass unless otherwise specified.

The aqueous ink composition for ballpoint pens according to the present invention (hereinafter sometimes referred to as "aqueous ink composition", "ink composition", or "composition") comprises a colorant and a phosphate ester-based ink composition. It comprises at least a surfactant, a substance represented by formula (1) and/or a salt thereof, and water. Each component constituting the water-based ink composition according to the present invention will be described below.

(coloring agent)
Conventional colorants can be used in the water-based ink composition for ballpoint pens of the present invention.
Pigments include inorganic pigments such as carbon black, metal oxides or metal salts, organic pigments such as organic dye pigments or lake pigments, lustrous luster pigments such as aluminum pigments, and fluorescent pigments. include acid dyes, basic dyes, direct dyes, reactive dyes, vat dyes, sulfur dyes, metallized dyes, cationic dyes and disperse dyes.
The content of the coloring material is applied in the range of 0.1 to 30% by mass with respect to the total mass of the ink composition.

Further, examples of coloring agents that can be applied to the ink composition include coloring agents that change color due to frictional heat.

The coloring material that changes color due to frictional heat is selected regardless of whether it is reversible or irreversible, if the handwriting changes color (hue change, transparency, or color disappearance) when the handwriting is rubbed with a friction body or the like and heated. can be applied In addition to the colorant itself that changes hue, it is also possible to change the hue by using a transparent (decolorized) colorant and a general-purpose colorant such as the above-described dyes and pigments.
Examples of the heat-discoloring coloring material include, for example, reversible types disclosed in JP-A-2012-219160 and JP-A-2014-5422, which are exemplified as cited documents, and JP-A-2010-229332. The irreversible types disclosed are applicable.
In particular, by encapsulating the thermochromic composition in microcapsules, the change in handwriting can be achieved stably for a long period of time without causing a change in composition, which is suitable. As the thermochromic composition encapsulated in the microcapsule pigment, from the viewpoint of repeated usability, accuracy of temperature change, etc., (a) an electron-donating color-forming organic compound, (b) an electron-accepting compound and (c) a reversible thermochromic composition comprising a reaction medium that determines the temperatures at which the two color reactions occur.

Examples of the reversible thermochromic composition include those described in Japanese Patent Publication No. 51-44706, Japanese Patent Publication No. 51-44707, Japanese Patent Publication No. 1-29398, etc. It changes color before and after, exhibits a discolored state in a temperature range above the high-temperature side color change point, and a colored state in a temperature range below the low-temperature side color change point. The other state is maintained as long as the heat or cold required to develop that state is applied, but returns to the state exhibited at room temperature when the heat or cold is no longer applied, and the hysteresis width is Heat-discolorable microcapsule pigments, in which a reversible thermochromic composition having relatively small characteristics (ΔH=1 to 7° C.) is encapsulated in microcapsules, can be applied.
Furthermore, relatively large hysteresis characteristics (ΔH = 8 to 50 ° C.), and exhibits large hysteresis characteristics described in JP-A-2006-137886, JP-A-2006-188660, JP-A-2008-45062, JP-A-2008-280523, etc. That is, the shape of the curve plotting the change in color density due to temperature change is greatly different when the temperature is increased from the lower temperature side than the discoloration temperature range and when the temperature is decreased from the higher temperature side than the discoloration temperature range. A reversible thermochromic composition that changes color along a path and retains color in a specific temperature range in a colored state in a low temperature range below the complete color development temperature or in a colorless state in a high temperature range above the complete color disappearance temperature. A heat-erasable microcapsule pigment containing is also applicable.
Specifically, the reversible thermochromic composition having color memory properties, which is applied to the ink for writing instruments, is a temperature at which the complete color development temperature can be obtained only in a freezer, a cold region, etc., that is, -50 to 0 ° C. , preferably -40 to -5 ° C., more preferably -30 to -10 ° C., and the temperature obtained from a familiar heating body such as a frictional heat by a friction body, a hair dryer, that is, 50 to 95 ° C. , preferably 50 to 90 ° C., more preferably 60 to 80 ° C., and specifying the ΔH value to 40 to 100 ° C., effectively maintaining the color exhibited in the normal state (daily life temperature range) can function.

Microencapsulation of the thermochromic composition includes interfacial polymerization method, interfacial polycondensation method, in situ polymerization method, in-liquid curing coating method, phase separation method from aqueous solution, phase separation method from organic solvent, melting dispersion cooling method, aerial suspension coating method, spray drying method, etc., which are appropriately selected according to the application. Furthermore, depending on the purpose, the surface of the microcapsule pigment may be further provided with a secondary resin film to impart durability, or the surface characteristics may be modified for practical use.

Water-based inks in which the coloring material is a dye and the content of the dye is 2% by mass or less with respect to the total mass of the ink composition is such that the ink jettability tends to decrease with repeated writing, although the reason is not clear. There is a tendency. The ink composition of the present invention maintains good ink jettability from the pen tip even at such a dye concentration, and maintains clear handwriting with suppressed handwriting faintness and line breakage over a long period of time. can be formed.

(Phosphate ester surfactant)
The ink composition contains a phosphate surfactant.
Phosphate ester-based surfactants smooth the rotation of the ball during writing and improve the ink ejection properties.

A known phosphate surfactant can be applied to the ink composition. Specifically, polyoxyethylene alkyl ether phosphates, polyoxyethylene alkylene ether phosphates, polyoxyethylene aryl ether phosphates, and polyoxyethylene polyoxypropylene alkyl ether phosphates can be exemplified. Examples of ethylene aryl ether phosphate include polyoxyethylene phenyl ether phosphate, polyoxyethylene dodecylphenyl ether phosphate, polyoxyethylene dinonylphenyl ether phosphate, polyoxyethylene monostyrylphenyl ether phosphate, Examples include polyoxyethylene distyrylphenyl ether phosphate, polyoxyethylene tristyrylphenyl ether phosphate, polyoxyethylene cumylphenyl ether phosphate, and polyoxyethylene naphthyl ether phosphate, all of which are preferably used. . The phosphate surfactant may be a sodium salt or an alkanolamine salt such as a monoalkanolamine salt, a dialkanolamine salt, or a trialkanolamine salt. Examples of commercially available products include Plysurf A212C, A215C, A208F, M208F, A208N, A208B, A219B, DB-01, A210D, and AL as Plysurf series (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), and the Phosphanol series. (manufactured by Toho Chemical Co., Ltd.), Phosphanol 2P, ML-200, GF-185, BH-650, ED-200, RA-600, ML-220, ML-240, RD-510Y, RS-410, RS -610, RS-710, RL-210, RL-310, RB-410, RD-710, RP-710, LF-200, RM-410, RM-510, SP-212, CP-120, 720, SC -6103, RD-720.LP-700, LP-500, LB-400, and Anstex series (manufactured by Toho Chemical Co., Ltd.), Anstex AK-25, AK-25B, SM-172, GF-339 , GF-199, ML-200, GF-185 and the like. Phosphate surfactants that can be applied to the ink composition are not limited to these.
A single type of phosphate surfactant may be used, or a plurality of types may be used in combination.

The content of the phosphate ester surfactant in the ink composition is preferably 0.1 to 3% by mass, more preferably 0.5 to 2% by mass, relative to the total mass of the ink composition. preferable. By setting the content of the phosphate ester-based surfactant in the ink composition within the above range, it is possible to improve the dissolution stability of the phosphate ester-based surfactant and facilitate smooth rotation of the ball during writing.

式中、ＸとＹは－Ｈ、－Ｒ、－ＯＨ、－ＯＲ、－ＮＨ_２、－ＮＨＲ、－ＮＲ_２から選ばれる官能基であり、Ｒはアルキル基である。ただし、Ｘ、Ｙ双方が水素である場合を除く。
前記した式（１）に示す物質の塩としては、アルカリ金属塩、アンモニウム塩、モノエタノールアミン、ジエタノールアミン、トリエタノールアミン等のアルカノールアミン塩が挙げられる。
式（１）に示す物質およびその塩は、前記したリン酸エステル系界面活性剤とともに適用されて筆記時の良好なインキ吐出性を持続的に発現させ、筆跡カスレや線トビが抑制された鮮明な筆跡を長期に亘って形成可能とする。
これは以下のメカニズムによるものと推測される。
ボールや、ボール受け座等のボール抱持室内面にインキ組成物が触れると、まずリン酸エステル系界面活性剤がボール表面やボール抱持室内面に速やかに吸着して筆記時にボールを滑らかに回転させることができる潤滑層を形成する。このリン酸エステル系界面活性剤のみからなる潤滑層はボールの回転によって生じる、ボールとボール接触部との摩擦が繰り返されることで失われやすいものの、この潤滑層に式（１）に示す物質やその塩が取り込まれることで、ボールの回転で容易に失われない強固な潤滑層が形成され、円滑なボールの回転が持続可能となる。
式（１）に示される物質とその塩は併用しても良い。 The water-based ink composition contains a substance represented by the following formula (1) or a salt thereof.

In the formula, X and Y are functional groups selected from --H, --R, --OH, --OR, --NH ₂ , --NHR and --NR ₂ , and R is an alkyl group. However, the case where both X and Y are hydrogen is excluded.
Examples of the salt of the substance represented by formula (1) include alkali metal salts, ammonium salts, alkanolamine salts such as monoethanolamine, diethanolamine and triethanolamine.
The substance represented by the formula (1) and its salt are applied together with the phosphate ester surfactant described above to continuously exhibit good ink jettability during writing, and to provide clear ink with suppressed faint writing and broken lines. It is possible to form a long-lasting handwriting.
This is presumed to be due to the following mechanism.
When the ink composition comes into contact with the ball or the inner surface of the ball holding chamber such as the ball receiving seat, the phosphoric acid ester surfactant quickly adheres to the surface of the ball and the inner surface of the ball holding chamber to smooth the ball during writing. Forms a lubricating layer that can be rotated. The lubricating layer consisting only of the phosphate ester-based surfactant is easily lost due to repeated friction between the ball and the ball contacting portion generated by the rotation of the ball. By incorporating the salt, a strong lubricating layer is formed that is not easily lost when the ball rotates, allowing the ball to continue to rotate smoothly.
The substance represented by Formula (1) and its salt may be used in combination.

Furthermore, the substance represented by the formula (1) and its salt can increase the wettability of the member forming the ink supply mechanism of the ballpoint pen, which will be described later, and improve the ink supply from the ink reservoir to the pen tip. .

In consideration of sustaining good ink jettability during writing, X and Y in Formula (1) are functional groups selected from —H, —OH, and —NH ₂ (provided that X and Y X and Y are preferably functional groups selected from —OH and —NH ₂ , and X and Y are —OH on one side and —OH on the other. is _-NH2 .

The content of the substance represented by formula (1) and/or its salt is preferably 0.05 to 2% by mass, more preferably 0.1 to 1.5% by mass, relative to the total mass of the ink composition. is more preferable, and 0.1 to 1% by mass is even more preferable. When the content is 0.05% by mass or more, the effect of improving the ink ejection property is sufficiently exhibited, and when the content exceeds 2% by mass, the color density due to the substance of formula (1) and its salt increases, so that the color is particularly pale. or white ink, the color of the ink may change.

Further, the relationship between the content A of the phosphate ester-based surfactant and the content B of the substance and/or salt thereof represented by formula (1) satisfies 0.01 ≤ B/A ≤ 1. Preferably, 0.05≦B/A≦0.7 is more preferred. When the content ratio is within the above range, good ink jettability tends to be maintained.

Preferably, the ink composition comprises a formalin condensate of naphthalenesulfonic acid.
The condensate can further suppress faint handwriting and broken lines, and can improve initial writing performance after the passage of time.
The formalin condensate of naphthalenesulfonic acid and the substance represented by the formula (1) and its salt have a naphthalene ring in common, so they have a high affinity, and are formed on the ball surface and the inner surface of the ball holding such as the ball seat. In addition, it is presumed that the condensate is further incorporated into the lubricating layer composed of the phosphoric acid ester-based surfactant and the substance of formula (1) and/or its salt, thereby further strengthening the lubricating layer.
The condensates may be alkali metal salts such as sodium salts.

The content of the formalin condensate of naphthalenesulfonic acid is preferably 0.5 to 5% by mass, preferably 1 to 3%, based on the total mass of the ink composition, in consideration of improving the initial writing performance after aging. % by mass is more preferred, and 1 to 2% by mass is even more preferred.

(thickener)
A thickener can be used in the water-based ink composition.
A conventionally known substance can be used as the thickener, but a substance capable of imparting shear thinning property to the ink composition (shear thinning agent) is preferable. The shear thinning agent can easily reduce the viscosity of the ink composition when a shearing force is applied to the ink from the ball while maintaining the high viscosity of the ink when it is still. While suppressing the sedimentation and aggregation of the pigment in the ink, the ink ejection property from the pen tip at the time of writing can be improved.

Specific examples of shear-thinning agents include tragacanth gum, pullulan, cyclodextrin, succinoglycan, xanthan gum, welan gum, λ-carrageenan, guar gum, locust bean gum and derivatives thereof, alginic acid alkyl esters, and methacrylic acid alkyl esters. A polymer with a molecular weight of 100,000 to 150,000 as a main component, a carbohydrate with gelling ability extracted from seaweed such as glucomannan and carrageenan, a poly N-vinyl-carboxylic acid amide crosslinked product, benzylidene sorbitol and benzylidene xylitol, or these derivatives, crosslinkable acrylic acid polymers, inorganic fine particles such as smectite and laponite, and the like.

Conventional general-purpose water-soluble organic solvents that are compatible with water can also be used in the ink composition. Examples of water-soluble organic solvents include ethanol, propanol, butanol, glycerin, sorbitol, triethanolamine, ethylene glycol, diethylene glycol, thiodiethylene glycol, hexylene glycol, 1,3-butanediol, neoprene glycol, polyethylene glycol, propylene glycol. , butylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, propylene glycol monoethyl ether, 2-pyrrolidone, N-methyl-2 - pyrrolidone and the like.
The water-soluble organic solvent can be used alone or in combination of two or more, and is used in the range of 2 to 60% by weight, preferably 5 to 35% by weight in the ink composition.

Furthermore, a pH adjuster can be used to adjust the pH to a desired level according to the properties of the ink composition.
As the pH adjuster, conventionally known acidic substances and basic substances can be applied. Examples of acidic substances include hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, carbonic acid, boric acid, lactic acid, citric acid, tartaric acid, malic acid, and the like. Examples of basic substances include strong alkalis such as sodium hydroxide and potassium hydroxide, and weak alkalis such as sodium carbonate, ammonia, sodium hydrogen phosphate and potassium hydrogen phosphate. Alkanolamines such as monoethanolamine, diethanolamine and triethanolamine are also applicable as the basic substance.

In addition, if necessary, rust inhibitors such as benzotriazole, tolyltriazole, saponin, phenolic acid, sodium salt of 1,2-benzthiazolin-3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, paraoxybenzoic acid Preservatives or fungicides such as propyl, 2,3,5,6-tetrachloro-4-(methylsulfonyl)pyridine, urea, sorbitol, mannitol, sucrose, glucose, reduced starch hydrolysate, sodium pyrophosphate Wetting agents such as antifoaming agents, fluorine-based surfactants and nonionic surfactants that improve ink permeability may also be used. Furthermore, the basic substance described above can also be used as a neutralizing agent for the substance represented by the formula (1).
Furthermore, metal soaps, polyalkylene glycol fatty acid esters, ethylene oxide addition type cationic surfactants, N-acyl amino acid surfactants, dicarboxylic acid type surfactants, β-alanine type surfactants, 2,5-dimercapto-1 , 3,4-thiadiazole and its salts and oligomers, 3-amino-5-mercapto-1,2,4-triazole, thiocarbamate, dimethyldithiocarbamate, α-lipoic acid, N-acyl-L-glutamic acid and L-lysine condensates and salts thereof are used.
In addition, N-vinyl-2-pyrrolidone oligomer, N-vinyl-2-piperidone oligomer, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, ε-caprolactam, N-vinyl-ε-caprolactam Addition of thickening inhibitors such as oligomers can also enhance functionality in the hive-and-recess form.

Furthermore, one or more water-soluble resins such as alkyd resins, acrylic resins, styrene-maleic acid copolymers, cellulose derivatives, polyvinylpyrrolidone, polyvinyl alcohol, dextrin may be added, urea, nonionic surfactants, sorbitol, One or two or more wetting agents such as mannitol, sucrose, glucose, reduced starch hydrolysate, sodium pyrophosphate and the like can also be added.

(Physical properties of aqueous ink composition)
The viscosity of the water-based ink composition is preferably 1 to 100 mPa·s, more preferably 2 to 70 mPa·s, measured at a shear rate of 384 sec ⁻¹ (20° C.). The viscosity of the ink composition can be measured using a rheometer (manufactured by TA Instruments, DISCOVERY HR-2, cone plate 40 mm, angle 1°). If the viscosity of the water-based ink composition is within the above numerical range, the ink jettability will be moderately good, and it will be easy to form clear handwriting without blurring or broken lines.

The water-based ink composition according to the present invention can be produced by any conventionally known method. Specifically, the necessary amount of each of the above components is blended and mixed with various stirrers such as a propeller stirrer, a homodisper, or a homomixer, and various dispersers such as a bead mill.

(ballpoint pen)
A ball-point pen filled with the water-based ink composition of the present invention will be described. A ballpoint pen includes a pen tip, an ink filling mechanism, an ink supply mechanism, and the like.

As the pen tip, a metal ball-point pen tip is used in which a ball is rotatably held in a ball house (ball holding chamber) of the ball-point pen tip body.

The ball house is, for example, formed by cutting a metal to form a ball receiving seat and an ink outlet inside, and a plurality of inward protrusions are provided on the inner surface near the tip of a metal pipe by pressing and deforming from the outer surface. A ball house in which an ink outflow gap extending radially outward in the radial direction from the central portion is formed between the inward protrusions can be applied. The contact area with the edge is relatively small, and a smooth writing feeling can be given with a low writing pressure.

The material of the ball and ball house has excellent strength and wear resistance, and the phosphate ester surfactant adheres to the surface, making it easy for the ball to rotate smoothly. A hard alloy or the like is preferably used.

A ball having an outer diameter of 0.1 to 2.0 mm can be applied to the ball held in the ball house.
In the ballpoint pen tip, an elastic member is arranged in the tip to spring the rear end of the ball forward, and when writing is not performed, the ball is pressed against the inner edge of the tip of the tip so as to be in a close contact state, and when writing, the pen pressure is applied. The ball can be retracted to allow the ink to flow out, thereby suppressing ink leakage when not in use.
The elastic member can be exemplified by a thin metal wire spring having a straight portion (rod portion) at one end of the spring, and is configured to be able to press with an elastic force of 5 to 40 g.

The ink filling mechanism may be configured to directly fill with the water-based ink composition, or may have an ink container or ink occlusion body capable of being filled with the water-based ink composition.
When the ball-point pen has an ink-absorbing body that can be filled with the water-based ink composition, the ink-absorbing body is preferably a bundle of fibers made of twisted fibers.
Also, the ink filling mechanism may be a cartridge that can be directly filled with the ink composition.

In addition, the ink supply mechanism is not particularly limited. ) A large number of discs are arranged in parallel with a comb groove-like interval, and slit-shaped ink guide grooves extending through the discs in the axial direction and ventilating grooves wider than the grooves are provided. A mechanism for supplying ink composition to the nib; (4 ) A mechanism for directly supplying a water-based ink composition to a pen tip from an ink container or barrel having a pen tip.
As for the ink reservoir having a pen tip, the ballpoint pen tip is provided directly at the tip of the ink reservoir tube or via a holder, and the rear end of the ink is filled with an ink backflow prevention body made of a viscous liquid such as grease. Any ink refill may be used.

The mechanism (3) is a preferable ink supply mechanism because it can stably supply ink from the ink reservoir to the ball-point pen tip and improve the ink ejection performance from the ball-point pen tip. Furthermore, as described above, in the ink composition of the present invention, the wettability of the members constituting the ink supply mechanism is enhanced by the substance represented by formula (1) or a salt thereof, so that the ink supply mechanism of (3) is It is possible to further increase the stability of ink supply.

The ballpoint pen may have a pen tip retraction mechanism. Examples of the pen tip retracting mechanism include a knock type, a rotating type, a sliding type, and the like. Moreover, it may be of a retractable type in which the pen tip can be accommodated in the barrel.

A ball-point pen containing the composition of the present invention can be configured by appropriately selecting a mechanism from the above-described pen tip, ink filling mechanism, ink supply mechanism, and pen tip retraction mechanism.

An embodiment of the invention is as follows.
(Example 1)
The following raw materials and blending amounts were stirred and mixed at room temperature for 1 hour to obtain a water-based ink composition for writing instruments.
・ Colorant 0.4% by mass
(Blue dye, product name: Water Blue 105, manufactured by Orient Chemical Industry Co., Ltd.)
・ Phosphate ester surfactant (polyoxyethylene styrylphenyl ether phosphate, product name: Plysurf AL, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 1.5% by mass
・Compound represented by formula (1) (X: —OH, Y: —NH ₂ ) 0.1% by mass
・ Benzisothiazolin-3-one (preservative, product name: Proxel XL-2, manufactured by Lonza Japan) 0.3% by mass
・Diethylene glycol 8% by mass
・Urea 5% by mass
・ Triethanolamine 2% by mass
・Water 82.7% by mass

(Examples 2 to 9, Comparative Examples 1 to 4)
Ink compositions of Examples 2 to 9 and Comparative Examples 1 to 4 were obtained by changing the types and amounts of components to be blended from Example 1 as shown in Table 1.
Details of the materials used in the above examples are as follows.
(1) Blue dye (product name: Water Blue 105, manufactured by Orient Chemical Industry Co., Ltd.)
(2) Yellow dye (product name: Quinoline Yellow WS300%, manufactured by Daiwa Kasei Co., Ltd.)
(3) Blue pigment (product name: Sandai Super Blue GLL (E), manufactured by Sanyo Pigment Co., Ltd., pigment 25% by mass dispersion)
(4) Phosphate ester-based surfactant (polyoxyethylene styrylphenyl ether phosphate, product name: Plysurf AL, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
(5) compounds represented by formula (1) (X=-OH, Y=-NH ₂ )
(6) a compound represented by formula (1) (both X and Y —OH)
(7) Formalin condensate of sodium naphthalenesulfonate (product name: Demoll N, manufactured by Kao Corporation)
(8) preservative (benzisothiazolin-3-one, product name: Proxel XL-2, manufactured by Lonza Japan)

The water-based ink compositions prepared were evaluated as follows. The results obtained were as described in Table 2.
Ballpoint pens used in the evaluation tests were prepared as follows.
Ballpoint pen: A metal ballpoint pen tip (material of the ball holding chamber: stainless steel) that rotatably holds a cemented carbide ball with an outer diameter of 0.7 mm, and an ink filling mechanism capable of directly filling the ink composition. , a slit-shaped ink guiding groove interposed between the ball-point pen tip and the ink filling mechanism, a large number of disk bodies arranged in parallel at intervals of a comb groove shape, and extending through the disk bodies in the axial direction, and the grooves; An ink supply that guides an ink composition to a ball-point pen tip through a pen core having a wider vent groove and an ink guide core for guiding ink from an ink reservoir to the pen tip. 2 g of the ink obtained in Examples and Comparative Examples was placed in a ballpoint pen (manufactured by Pilot Corporation, product name: Hi-Tekpoint V7).

(1) Evaluation of Ink Ejection Stability Using the ballpoint pen, continuous writing was performed on the test paper, and the handwriting was observed and evaluated. The diameter of one circle was 3 cm, and the writing conditions were set at a writing distance of 1000 m, a writing load of 100 g, a writing angle of 62.5°, and a writing speed of 4 m/min. Trade name: NPi Form <55> (manufactured by Nippon Paper Industries Co., Ltd.) was used as the test paper. As for the evaluation criteria, S and A were accepted, and B was rejected.
S: No faint handwriting or broken lines are observed.
A: Slight faint handwriting and broken lines were observed, but there was no practical problem.
B: Scratches in handwriting and broken lines are conspicuous, and there is a problem in practical use.
(2) Evaluation of stability over time 1: Initial writing property The ballpoint pen with the cap attached was stored at 50 ° C. for 60 days, and after returning the ballpoint pen after storage to room temperature, 12 consecutive circles (diameter: 3 cm) were written. and observed the handwriting. The writing conditions were as follows: writing load: 100 g, writing angle: 70°, writing speed: writing 12 circles in 4 seconds. The same kind of paper as the test paper was used. As for the evaluation criteria, S and A were accepted, and B was rejected.
S: No faint handwriting or broken lines are observed.
A: Slight faint handwriting and broken lines were observed, but there was no practical problem.
B: Scratches in handwriting and broken lines are conspicuous, and there is a problem in practical use.
(3) Evaluation of stability over time 2: Ink ejection stability The ballpoint pen evaluated in "Evaluation of stability over time 1" was used to write on test paper, and the handwriting was observed. The writing conditions and the test paper were the same as those in "Evaluation of Ink Discharge Stability". As for the evaluation criteria, S and A were accepted, and B was rejected.
S: No faint handwriting or broken lines are observed.
A: Slight faint handwriting and broken lines were observed, but there was no practical problem.
B: Scratches in handwriting and broken lines are conspicuous, and there is a problem in practical use.

The test results are given in Table 2 below.

Claims (9)

An ink contained in a ball-point pen having a metal ball-point pen tip, comprising a coloring agent, a phosphate surfactant, a substance represented by the following formula (1) and/or its salt, and water: A water-based ink composition for a ball-point pen containing.

wherein X and Y are functional groups selected from -H, -R, -OH, -OR, -NH ₂ , -NHR and -NR ₂ , and R is an alkyl group. However, the case where both X and Y are hydrogen is excluded. 2. The aqueous ink composition according to claim 1, wherein said X and Y are functional groups selected from -H, -OH and _-NH2 (except when both X and Y are hydrogen). Based on the total weight of the ink composition, the content of the phosphate ester surfactant is 0.1 to 3% by mass, and the content of the substance represented by formula (1) and/or a salt thereof is 0.1% by mass. 3. The water-based ink composition according to claim 1, wherein the content is 05 to 2% by mass. Claim 1, wherein the relationship between the content A of the phosphate ester surfactant and the content B of the substance represented by formula (1) and/or a salt thereof satisfies 0.01 ≤ B/A ≤ 1. 4. The water-based ink composition according to any one of items 1 to 3. The coloring material is a dye. The water-based ink composition according to any one of claims 1 to 4. 6. The water-based ink composition according to claim 5, wherein the dye content is 2% by mass or less based on the total mass of the water-based ink composition. An aqueous ink composition according to any one of claims 1 to 6, comprising a formalin condensate of naphthalenesulfonic acid. A ballpoint pen comprising a ballpoint pen tip made of metal and containing the water-based ink composition according to any one of claims 1 to 7. A large number of discs are arranged in parallel with a comb groove-like interval, slit-like ink guide grooves running through the discs in the axial direction and ventilation grooves wider than the grooves are provided, and an ink reservoir is provided at the center of the shaft. 9. A ballpoint pen according to claim 8, comprising a pen core in which an ink guide core is arranged for guiding ink from the pen to the nib.