JP2024014740A - Water-based ink composition for ballpoint pen and ballpoint pen containing the same - Google Patents

Abstract

[Object] To provide a water-based ink composition for a ballpoint pen that can highly suppress corrosion of a cemented carbide ball containing cobalt as a metal binder and has excellent stability over time. [Solution] One or more (A) selected from 1,2,3-benzotriazole, tolyltriazole, and carboxybenzotriazole, a substance represented by general formula (1), and 5-mercapto-3-phenyl- Containing at least one or more selected from 1,3,4-thiadiazole (B), a phosphate ester surfactant (C), a coloring agent, and water, (A), (B) , (C) in a predetermined amount. [Selection diagram] None

Description

The present invention relates to a water-based ink composition for ballpoint pens.

Balls for ballpoint pens are made of silicon carbide, zirconium oxide, tungsten carbide, etc. as the main components, and are inexpensive and provide high writing performance. Alloy balls are widely used.

However, since metals such as cobalt, chromium, titanium, and nickel are mainly used as the binder, when used in water-based ballpoint pens, the binder deteriorates over time due to corrosive components such as dissolved oxygen in the ink. When the binder is eluted into the ink and lost from the ball, the crystal particles of tungsten carbide, which is the main component, may fall off, or the eluted binder becomes metal oxide, becomes insolubilized, and adheres to the ball surface again. , so-called corrosion may occur. The corrosion increases the unevenness of the ball surface, which may impede smooth rotation of the ball and cause problems in writing.
In particular, cemented carbide balls that use cobalt or nickel as metal binders are highly versatile, but have the disadvantage that they tend to corrode over time in water-based ballpoint pens due to the high content of metal binders. .

Therefore, as a method for preventing the above-mentioned corrosion over time, a method has been disclosed in which a sulfide compound or an amino derivative of benzotriazole is added to the ink (see, for example, Patent Documents 1 and 2).

However, when the sulfide compound is added, depending on the structure of the compound, problems may occur such as emitting an odor or precipitating over a long period of time, making it difficult to obtain a sufficient corrosion inhibiting effect.
In addition, amino derivatives of benzotriazole have low solubility in aqueous media, so they lack dissolution stability in ink, and although they are effective against copper-based metals, they are not effective against carbides. It is impossible to obtain effective results.

Japanese Patent Application Publication No. 2004-115684 Tokuhei 1-23512

The present invention provides a water-based ink composition for ballpoint pens that can highly suppress corrosion of cemented carbide balls containing cobalt as a metal binder and has excellent stability over time.

式中、ＲはＣＨ_３、ＮＨ_２、ＳＭから選ばれるいずれかであり、該Ｍおよび一般式（１）におけるＭは、独立して、水素、アルカリ金属、アンモニウム、アルカノールアミン、シクロヘキシルアミン、およびシクロヘキシルアルカノールアミンから選ばれるいずれかである。
２．前記（Ａ）、（Ｂ）、および（Ｃ）の含有率が下記一般式（２）の関係を満たす、第１項に記載のインキ組成物。
（Ａ）の含有率＋（Ｂ）の含有率 ＞（Ｃ）の含有率 （２）
３．第１項または第２項に記載のインキ組成物を収容し、コバルトを金属結合材として含む超硬合金製のボールを備えてなるボールペン。」とする。 "1. One or more (A) selected from 1,2,3-benzotriazole, tolyltriazole, and carboxybenzotriazole, a substance represented by the following general formula (1), and 5-mercapto-3-phenyl- An ink composition comprising at least one selected from 1,3,4-thiadiazole (B), a phosphoric acid ester surfactant (C), a colorant, and water,
Based on the total mass of the ink composition, the content of (A) is 0.01 to 2% by mass, the content of (B) is 0.1 to 3% by mass, and the content of (C) is A water-based ink composition for a ballpoint pen having a content of 0.1 to 2% by mass.

In the formula, R is one selected from CH ₃ , NH ₂ , and SM, and M and M in general formula (1) are independently hydrogen, alkali metal, ammonium, alkanolamine, cyclohexylamine, and One selected from cyclohexylalkanolamines.
2. The ink composition according to item 1, wherein the contents of (A), (B), and (C) satisfy the following general formula (2).
Content rate of (A) + Content rate of (B) > Content rate of (C) (2)
3. A ballpoint pen containing the ink composition according to item 1 or 2 and comprising a ball made of cemented carbide containing cobalt as a metal binder. ”.

According to the present invention, there is provided a water-based ink composition for a ballpoint pen that can highly suppress corrosion of a cemented carbide ball containing cobalt as a metal binding material and has excellent stability over time, and a water-based ink composition containing the composition that contains cobalt as a metal binding material. A ballpoint pen is provided which includes a ball made of cemented carbide.

Embodiments of the present invention will be described in detail below. In addition, in this specification, "parts", "%", "ratio", etc. indicating a composition are based on mass unless otherwise specified.

The water-based ink composition for ballpoint pens according to the present invention (hereinafter, may be referred to as "aqueous ink composition", "ink composition", or "composition") includes a colorant, 1, 2, One or more selected from 3-benzotriazole, tolyltriazole, and carboxybenzotriazole, a substance represented by general formula (1), and 1 selected from 5-mercapto-3-phenyl-1,3,4-thiadiazole The surfactant contains at least one species, a phosphate ester surfactant, and water. In this specification, the group consisting of 1,2,3-benzotriazole, tolyltriazole, and carboxybenzotriazole is referred to as a triazole substance, a substance represented by general formula (1), and 5-mercapto-3-phenyl- The group consisting of 1,3,4-thiadiazole is sometimes referred to as thiadiazole substances.
Even if any of the triazole-based substances, thiadiazole-based substances, and phosphate ester surfactants are missing, corrosion of cemented carbide balls containing cobalt as a metal binder can be suppressed, and an ink with excellent stability over time is formed. It becomes difficult to do so.
Each component constituting the aqueous ink composition according to the present invention will be explained below.

The content of the triazole substance is 0.01 to 2% by mass, preferably 0.05 to 1.5% by mass, and 0.1 to 1.5% by mass based on the total mass of the ink composition. It is more preferable that
When the content of the triazole-based substance is within the above range, the stability of the ink over time is improved, and excessive elution of cobalt from the cemented carbide balls can be suppressed to sufficiently suppress corrosion of the balls. , even if it is added in excess of 1.5% by mass, the corrosion inhibiting effect will not be greatly improved.
One or more types of triazole-based substances can be used. Further, the triazole-based substance may be an alkali metal salt.

式中、ＲはＣＨ_３、ＮＨ_２、ＳＭから選ばれるいずれかであり、該Ｍおよび一般式（１）におけるＭは、独立して、水素、アルカリ金属、アンモニウム、アルカノールアミン、シクロヘキシルアミン、およびシクロヘキシルアルカノールアミンから選ばれるいずれかである。 Examples of thiadiazole-based substances include substances represented by the following general formula (1) and 5-mercapto-3-phenyl-1,3,4-thiadiazole.

In the formula, R is one selected from CH ₃ , NH ₂ , and SM, and M and M in general formula (1) are independently hydrogen, alkali metal, ammonium, alkanolamine, cyclohexylamine, and One selected from cyclohexylalkanolamines.

The content of the thiadiazole-based substance is 0.1 to 3% by mass based on the total mass of the ink composition, considering that the elution of cobalt from the cemented carbide ball is suppressed and the corrosion of the ball is suppressed. It is preferably 0.2 to 3% by mass, more preferably 0.2 to 2.5% by mass. When the content of the thiadiazole-based substance is within the above range, the stability of the ink over time is improved, and excessive elution of cobalt from the cemented carbide balls can be suppressed, thereby sufficiently suppressing corrosion of the balls. , even if it is added in an amount exceeding 3% by mass, the corrosion inhibiting effect will not be greatly improved.
One type or two or more types of thiadiazole-based substances can be used.

Conventionally known phosphate surfactants can be used, such as polyoxyethylene alkyl ether phosphate, polyoxyethylene alkylene ether phosphate, polyoxyethylene aryl ether phosphate, polyoxyethylene Examples of polyoxypropylene alkyl ether phosphates include polyoxyethylene phenyl ether phosphates, polyoxyethylene phenyl ether phosphates, polyoxyethylene dodecyl phenyl ether phosphates, and polyoxyethylene dinonylphenyl ethers. Phosphate ester, polyoxyethylene monostyrylphenyl ether phosphate, polyoxyethylene distyrylphenyl ether phosphate, polyoxyethylene tristyrylphenyl ether phosphate, polyoxyethylene cumyl phenyl ether phosphate, polyoxy An example is ethylene naphthyl ether phosphate, and any of them are preferably used. The phosphate ester surfactant may be a sodium salt or an alkanolamine salt such as a monoalkanolamine salt, a dialkanolamine salt, or a trialkanolamine salt. Commercially available products include, for example, the Plysurf series (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.) such as Plysurf A212C, A215C, A208F, M208F, A208N, A208B, A219B, DB-01, A210D, and Plysurf A210D. AL is listed, and the phosphanol series (manufactured by Toho Chemical Industry Co., Ltd.) includes phosphanol 2P, ML-200, GF-185, BH-650, ED-200, RA-600, and 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 , the same LB-400, and the Anstex series (manufactured by Toho Chemical Co., Ltd.) include the Anstex AK-25, the same AK-25B, the same SM-172, the same GF-339, the same GF-199, and the same ML-200. , GF-185, etc. Phosphate ester surfactants that can be applied to the ink composition are not limited to these.
A single type of phosphate ester surfactant may be used, or a plurality of types may be used in combination.

The content of the phosphoric acid ester surfactant is 0.000% based on the total mass of the ink composition, in order to suppress the corrosion of the cemented carbide balls without impairing the stability over time and writability of the ink. The amount is 1 to 2% by weight, preferably 0.2 to 1.5% by weight, and more preferably 0.2 to 1.0% by weight.

Furthermore, in order to suppress corrosion of the cemented carbide balls without impairing the temporal stability and writing properties of the ink, the content of the triazole-based substance (A), the content of the thiadiazole-based substance (B), It is preferable that the relationship between the content of the phosphoric acid ester surfactant (C) and the content of the phosphate ester surfactant (C) satisfies the following general formula (2).
Content rate of (A) + Content rate of (B) > Content rate of (C)... (2)
The contents of (A), (B), and (C) are based on the total mass of the ink composition.

(Coloring material)
The water-based ink composition for ballpoint pens of the present invention can use conventional colorants.
Pigments include inorganic pigments such as carbon black, metal oxides or metal salts, organic pigments such as organic dye pigments or lake pigments, and lustrous and bright pigments such as aluminum pigments, and fluorescent pigments, and as dyes. Examples include acid dyes, basic dyes, direct dyes, reactive dyes, vat dyes, sulfur dyes, metal-containing dyes, cationic dyes, and disperse dyes.
The content of the colorant is applied in a range of 0.1 to 30% by mass based on the total mass of the ink composition.

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

As the colorant that changes color due to frictional heat, select one that changes the color of the handwriting (changes in hue, becomes transparent, or disappears) by rubbing the handwriting with a friction body and heating it, regardless of whether it is reversible or irreversible. applicable. In addition to the coloring material itself changing its hue, it is also possible to create a structure in which the hue changes by using a transparentizing (decolorizing) coloring material and a general-purpose coloring material such as the above-mentioned dyes and pigments.
As the coloring material that changes color when heated, for example, the reversible type disclosed in JP-A No. 2012-219160, JP-A No. 2014-5422, etc., and the one disclosed in JP-A No. 2010-229332, etc., are cited as examples. The disclosed irreversible types are applicable.
In particular, the change in handwriting can be stably expressed over a long period of time without any composition change by encapsulating the thermochromic composition in microcapsules, which is suitable. The thermochromic composition contained in the microcapsule pigment may be (a) an electron-donating color-forming organic compound, or (b) an electron-accepting compound, from the viewpoint of repeatability, accuracy of temperature changes, etc. , (c) A reversible thermochromic composition comprising a reaction medium that determines the temperature at which the color reaction of both of the above occurs is suitable.

The reversible thermochromic composition has a temperature that changes at a predetermined temperature (color change point) as 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 decolored state in a temperature range above the high temperature side discoloration point, and a colored state in a temperature range below the low temperature side discoloration point, and of the above two states, only one specific state exists in the normal temperature range, The other state is maintained as long as the heat or cold required to bring it about is applied, but when the heat or cold is no longer applied, it returns to the state it exhibits at room temperature, with a hysteresis width. A heat-decolorable microcapsule pigment in which a reversible thermochromic composition having relatively small characteristics (ΔH=1 to 7° C.) is encapsulated in microcapsules can be used.
Furthermore, relatively large hysteresis characteristics (ΔH=8 to 50 °C), or exhibit large hysteresis characteristics as described in JP-A No. 2006-137886, JP-A No. 2006-188660, JP-A No. 2008-45062, JP-A No. 2008-280523, etc. In other words, the shape of the curve plotting the change in coloring density due to temperature change is significantly different when the temperature is raised from a lower side than the discoloration temperature range and when it is lowered from a higher temperature side than the discoloration temperature range. A reversible thermochromic composition that changes color along a specific temperature range, and exhibits color development in a low temperature range below the complete color development temperature or discoloration state in a high temperature range above the complete color discoloration temperature, and has color memory in a specific temperature range. Microcapsule pigments that are color-erasable by heating can also be applied.
Specifically, the reversible thermochromic composition having color memory, which is applied to writing instrument ink, has a temperature at which the full color development temperature can only be obtained in a freezing room, a cold region, etc., that is, -50 to 0°C. , preferably -40 to -5°C, more preferably -30 to -10°C, and the complete color erasure temperature is the temperature obtained from frictional heat from a friction body or a familiar heating body such as a hair dryer, that is, 50 to 95°C. , preferably in the range of 50 to 90°C, more preferably 60 to 80°C, and specifying the ΔH value in the range of 40 to 100°C, it is possible to effectively maintain the color that appears under normal conditions (daily living temperature range). It can be made to work.

The thermochromic composition can be microencapsulated by interfacial polymerization, interfacial polycondensation, in-situ polymerization, in-liquid curing coating, phase separation from aqueous solution, phase separation from organic solvents, melting, dispersion, and cooling. method, air suspension coating method, spray drying method, etc., which are appropriately selected depending on the purpose. Furthermore, depending on the purpose, a secondary resin film can be further provided on the surface of the microcapsule pigment to impart durability or to modify the surface characteristics for practical use.

(Thickener)
A thickener can be used in the aqueous ink composition.
As the thickener, conventionally known substances can be used, but preferably a substance that can impart shear thinning properties to the ink composition (shear thinning agent). The shear thinning agent can easily reduce the viscosity of the ink composition when shear force is applied to the ink from the balls, while maintaining the high viscosity of the ink when it is left still. It is possible to suppress sedimentation and aggregation of the pigment in the ink while improving ink ejection properties from the pen tip during writing.

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

Conventional 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, and 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 - Examples include pyrrolidone.
The water-soluble organic solvent may be used alone or in combination of two or more, and is used in an amount of 2 to 60% by weight, preferably 5 to 35% by weight in the ink composition.

Furthermore, a pH adjuster may be used to adjust the pH to a desired value depending on the characteristics of the ink composition.
As the pH adjuster, conventionally known acidic substances and basic substances can be used. 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, etc. 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. Furthermore, alkanolamines such as monoethanolamine, diethanolamine, and triethanolamine can also be used as the basic substance.

In addition, rust inhibitors such as saponin, carbolic acid, sodium salt of 1,2-benzthiazolin 3-one, sodium benzoate, sodium dehydroacetate, potassium sorbate, propyl paraoxybenzoate, 2,3, Preservatives or fungicides such as 5,6-tetrachloro-4-(methylsulfonyl)pyridine, wetting agents such as urea, sorbitol, mannitol, sucrose, glucose, reduced starch hydrolyzate, sodium pyrophosphate, etc. Foaming agents, fluorosurfactants 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 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 oligomers, thiocarbamates, dimethyldithiocarbamates, α-lipoic acid, condensates of N-acyl-L-glutamic acid and L-lysine, and salts thereof.
In addition, oligomers of N-vinyl-2-pyrrolidone, oligomers of N-vinyl-2-piperidone, N-vinyl-2-pyrrolidone, N-cyclohexyl-2-pyrrolidone, ε-caprolactam, and N-vinyl-ε-caprolactam are also available. Addition of thickening inhibitors such as oligomers can also enhance functionality in the retractable form.

Furthermore, one or more water-soluble resins such as alkyd resin, acrylic resin, styrene-maleic acid copolymer, cellulose derivative, polyvinylpyrrolidone, polyvinyl alcohol, and dextrin may be added, or urea, nonionic surfactant, sorbitol, One or more types of wetting agents such as mannitol, sucrose, glucose, reduced starch hydrolyzate, and sodium pyrophosphate can also be added.

(ballpoint pen)
A ballpoint pen filled with the aqueous 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.

A metal ballpoint pen tip is used as the pen tip, which has a ball rotatably held in a ball house (ball holding chamber) of the ballpoint pen tip body.

A ball house is, for example, one in which a ball receiving seat and an ink outlet are formed by cutting metal, or a plurality of inward protrusions are formed on the inner surface near the tip of a metal pipe by pressing deformation from the outer surface. A ball house in which an ink outflow gap extending radially outward from the center can be formed between the inward protruding parts, and in particular, a ball house in which inward protruding parts are provided by pressure deformation is suitable for forming an ink flow gap between the inward protruding parts. The contact area with the edge is relatively small, giving a smooth writing feel with low writing pressure.

The balls held in the ball house are made of, for example, cemented carbide, stainless steel, ruby, ceramic, etc., and have an outer diameter of 0.1 to 2.0 mm. Balls made of such a cemented carbide can be preferably used because they are excellent in inhibiting corrosion of balls made of a cemented carbide containing cobalt in the metal binding material.
The ballpoint pen tip has a resilient member inside the tip that springs the rear end of the ball forward, so that when not writing, the ball is pressed against the inner edge of the tip to create a close contact state, and when writing, the ball is pressed against the inner edge of the tip, and when writing, the ball is pressed against the inner edge of the tip to create a close contact state. It is also possible to configure the ink to flow out by retracting the ball, thereby suppressing ink leakage when not in use.
The elastic member may be, for example, a spring made of a thin metal wire, or one having a straight portion (rod portion) at one end of the spring, and is configured to be able to be pressed with an elastic force of 5 to 40 g.

The ink filling mechanism may be configured to directly fill the aqueous ink composition, or may include an ink container or an ink storage body capable of being filled with the aqueous ink composition.
When the ballpoint pen is equipped with an ink storage body that can be filled with an aqueous ink composition, the ink storage body is preferably a fiber bundle made of twisted fibers.
Further, the ink filling mechanism may be a cartridge that can be directly filled with the ink composition.

Further, the ink supply mechanism is not particularly limited, and includes, for example, (1) a mechanism that includes an ink guide core made of a fiber bundle as an ink flow rate regulating member and guides the aqueous ink composition to the pen tip; ) A large number of disk bodies are arranged in parallel with comb groove-like intervals, and a slit-shaped ink guide groove that runs vertically through the disk body in the axial direction and a ventilation groove that is wider than the groove are provided, so that the ink guide groove can pass through the ink guide groove. (3) a mechanism for supplying an ink composition to a pen nib; (3) a large number of disk bodies arranged in parallel with comb-like intervals; a slit-shaped ink guiding groove extending longitudinally through the disk body; and a mechanism thicker than the groove; A mechanism for guiding an ink composition to a pen nib via a pen nib, which is provided with a ventilation groove of a width and an ink guiding nib disposed in the axial center for guiding ink from an ink reservoir to a nib, (4) ) A mechanism for directly supplying the water-based ink composition to the pen tip from an ink container or barrel provided with the pen tip can be mentioned.
The ink container equipped with a pen tip is provided with the ballpoint pen tip directly or via a holder at the tip of the ink storage tube, and the rear end of the ink pen is filled with an ink backflow preventer made of a viscous liquid such as grease. An ink refill may be used.

The ballpoint pen may be equipped with a pen tip retraction mechanism. Examples of the pen tip ejection/retraction mechanism include a knock type, a rotating type, and a sliding type. Alternatively, it may be a retractable type in which the pen tip can be accommodated within the barrel.

A ballpoint pen containing the composition of the present invention can be constructed by appropriately selecting a mechanism from among the above-mentioned pen nib, ink filling mechanism, ink supply mechanism, and pen nib projecting/retracting mechanism.

Handwriting obtained by writing on a writing surface using a ballpoint pen in which a coloring material that changes color due to frictional heat is applied to the ink can be changed in color using a heating tool or a cooling tool. Examples of the heating tool include an electrical heating discoloration tool equipped with a resistance heating element, a heat discoloration tool filled with hot water, etc., and a hair dryer, but preferably, a friction member is used as a means for changing color by a simple method. It will be done. That is, the ballpoint pen may further include a friction member.

As the friction member, an elastic body such as a plastic foam, or a viscoelastic body, which is highly elastic and can generate appropriate friction and generate frictional heat during rubbing, is suitable. It is also possible to rub the handwriting using an eraser, but since eraser scum is generated during friction, the above-mentioned friction member that hardly generates eraser scum is preferably used. As the material of the friction member, silicone resin, SEBS resin (styrene ethylene butadiene styrene block copolymer), polyester resin, α-olefin copolymer, etc. are used.

The friction member can be a member (friction body) of any shape that is separate from the ballpoint pen, and this and the ballpoint pen can be combined to form a writing instrument set, but by providing the friction member in the ballpoint pen, it is superior in portability.
In the case of a ballpoint pen equipped with a cap, the location where the friction member is provided is not particularly limited, but for example, if the cap itself is formed from the friction member, the barrel itself is formed from the friction member, or a clip is provided The clip itself may be formed of a friction member, or a friction member may be provided at the tip (top) of the cap or the rear end of the barrel (portion where the writing tip is not provided).
In the case of a retractable ballpoint pen, the location where the friction member is provided is not particularly limited. For example, the barrel itself may be made of a friction member, or if a clip is provided, the clip itself may be made of a friction member, or the vicinity of the barrel opening, the rear end of the barrel (where the writing tip is not provided), or A friction member may be provided in the knock portion.

Examples of the cooling device include a cold color changing device using a Peltier element, a cold color changing device filled with a refrigerant such as cold water or ice chips, and a refrigerator or freezer.

Examples of the invention are as follows.
(Example 1)
A water-based ink composition for writing instruments was obtained by stirring and mixing the following raw materials and blending amounts at room temperature for 1 hour.
・Coloring agent 7.0% by mass
(Red dye, product name: Food Red No. 104)
・1,2,3-benzotriazole 0.3% by mass
・Substance shown in formula (1) (R: -SH, M: -H) 0.3% by mass
・Phosphate ester surfactant 0.5% by mass
(Polyoxyethylene styrylphenyl ether phosphate ester, product name: Pricesurf AL, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
・Triethanolamine 1.0% by mass
・Diethylene glycol 10.0% by mass
・Glycerin 5.0% by mass
・Water 75.9% by mass

(Examples 2 to 14, Comparative Examples 1 to 11)
Ink compositions of Examples 2 to 14 and Comparative Examples 1 to 11 were obtained by changing the types and amounts of ingredients to be added to Example 1 as shown in Tables 1 and 2.
Details of the materials used in the above examples are as follows.
(1) Red dye (Food Red No. 104)
(2) Blue pigment (Acid Blue 90)
(3) Polyoxyethylene styryl phenyl ether phosphate ester, (product name: Plysurf AL, manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
(4) Polyoxyethylene tridecyl ether phosphate ester (product name: Plysurf A-212C, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
(5) Polymer block copolymer (40% by mass aqueous solution, product name: DISPERBYK-190, manufactured by BYK)

A ballpoint pen was produced using the prepared ink composition and evaluated as follows. The results obtained were as shown in Tables 3 and 4.

Preparation of Ballpoint Pen Refill Each of the obtained ink compositions is ink made of polypropylene resin and has a ballpoint pen tip at the tip that rotatably holds a ball with an outer diameter of 0.7 mm made of cemented carbide containing cobalt as a metal binding material. The inside of the storage tube was filled with an ink backflow preventer made of a viscous liquid at the rear end. Next, a tail plug was fitted to the rear part of the pipe to obtain a ballpoint pen refill.

Production of Ballpoint Pen The obtained ballpoint pen refill was attached to the exterior of a retractable ballpoint pen (trade name: V Corn Knock 07, manufactured by Pilot Corporation) to produce a ballpoint pen.
Note that writing paper A conforming to the old JIS P3201 was used as the test paper for writing.

(1) Evaluation of corrosion resistance of cemented carbide ball The ballpoint pen was stored in an environment of 50°C and 90% RH for 60 days, and the ball surface after storage was examined using an electron microscope (product name: tabletop microscope MiniscopeTM-1000, Hitachi (manufactured by Hi-Technologies). As for the evaluation criteria, A, B, and C were considered to be passed, and D was judged to be failed.
A: No surface roughness was observed, and no change was observed compared to the ball surface before storage.
B: Although surface roughness is observed compared to the surface of the ball before storage, there is no problem in writing and it is possible to write with the same feeling as the first stroke.
C: Surface roughness is observed compared to the ball surface before storage. There is no problem with writing, but the writing feels heavier compared to the first stroke.
D: Significant roughness was observed on the ball surface compared to the ball surface before storage, making writing difficult.
(2) Evaluation of cobalt elution from cemented carbide balls The cobalt content (unit: mass %) in cemented carbide balls before and after storage in the above environment was measured using an energy dispersive X-ray fluorescence spectrometer (product name: The measurement was performed using an energy dispersive X-ray analyzer SwiftED-TM (manufactured by Hitachi High-Technologies, Inc.) exclusively for MiniscopeTM. Incidentally, the amount of cobalt in the ball before storage was 10% by mass.
(3) Appearance of ink The ink was taken out from the ballpoint pen after storage and observed under an optical microscope. A was considered a pass and B was a fail.
A: No significant change was observed compared to the ink before storage.
B: Precipitates are observed.

The test results are shown in Tables 3 and 4 below.

Claims (3)

One or more (A) selected from 1,2,3-benzotriazole, tolyltriazole, and carboxybenzotriazole, a substance represented by the following general formula (1), and 5-mercapto-3-phenyl-1,3 , 4-thiadiazole (B), a phosphoric acid ester surfactant (C), a coloring material, and water, the ink composition comprising:
Based on the total mass of the ink composition, the content of (A) is 0.01 to 2% by mass, the content of (B) is 0.1 to 3% by mass, and the content of (C) is A water-based ink composition for a ballpoint pen having a content of 0.1 to 2% by mass.

In the formula, R is one selected from CH ₃ , NH ₂ , and SM, and M and M in general formula (1) are independently hydrogen, alkali metal, ammonium, alkanolamine, cyclohexylamine, and One selected from cyclohexylalkanolamines. The ink composition according to claim 1, wherein the contents of (A), (B), and (C) satisfy the following general formula (2).
Content rate of (A) + Content rate of (B) > Content rate of (C) (2) A ballpoint pen containing the ink composition according to claim 1 or 2 and comprising a ball made of cemented carbide containing cobalt as a metal binder.