JP7341480B2 - Ink composition for water-based ballpoint pens, water-based ballpoint pen refills, and water-based ballpoint pens - Google Patents

Description

The present invention provides (1) an aqueous ink composition for a ballpoint pen having a silicon carbide ball, and (2) a ballpoint pen tip rotatably holding a silicon carbide ball at the tip of an ink storage cylinder, directly or as a connecting member. (3) an aqueous ballpoint pen refill, the ink storage cylinder being filled with an aqueous ink composition for a ballpoint pen having the silicon carbide balls; Regarding the water-based ballpoint pen placed inside.

Alumina, zirconia, cemented carbide, and the like have been studied and used as balls for water-based ballpoint pens. However, these balls have problems such as corrosion due to water-based ink compositions and ink retention ability, and are not satisfactory in terms of writing characteristics, abrasion resistance, etc.
For this reason, the use of silicon carbide as the ball for use in water-based ballpoint pens is being considered. Although silicon carbide has excellent corrosion resistance and excellent water-based ink retention ability, it does not provide a smooth writing feel, and improvements have been desired.
Patent Documents 1 to 3 describe water-based ink compositions used in water-based ballpoint pens having silicon carbide balls. However, these water-based ink compositions cannot be said to be designed on the premise that they will be used exclusively for silicon carbide balls. For this reason, when silicon carbide is used as a ball, the writing quality and smoothness are not satisfactory.

Japanese Patent Application Publication No. 2008-163091 Japanese Patent Application Publication No. 2001-121868 JP2019-206630A

As a result of further investigation, the present inventor found that in a water-based ballpoint pen with silicon carbide balls, an oxide film (silica film) is formed on the surface of the silicon carbide ball, and the oxide film combines with OH in water to form SiOH. It has been found that it is thought that water is adsorbed by the formation of a multilayer film on the surface of silicon carbide, thereby increasing the lubricity. By using a specific water-based ink composition and a silicon carbide ball in combination, the coefficient of dynamic friction between the silicon carbide ball and the ball seat is reduced, resulting in a smooth writing experience and an excellent water-based ink composition. It has been found that a ballpoint pen can be formed.
The present invention provides a water-based ink for a ballpoint pen having a silicon carbide ball, which has a small coefficient of dynamic friction between the silicon carbide ball and the ball seat, has a smooth writing feel, and can form a water-based ballpoint pen with an excellent writing feeling. The problem is to obtain a composition.

As a result of intensive studies aimed at solving the above problems, the inventors of the present invention discovered that the above problems could be solved by the following water-based ink composition, water-based ballpoint pen refill, and water-based ballpoint pen, and were able to complete the present invention. Ta. Specifically, the details are as follows.
[1] A water-based ink composition for a ballpoint pen having a silicon carbide ball, which is represented by the following general formula (I) and contains a phosphoric acid ester surfactant having an HLB of 6 or more and an acid value of 120 or more. .
(In the formula: n is an integer from 0 to 20. R ¹ is an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, or an unsaturated hydrocarbon group having 4 or more carbon atoms. ² is M or -(CH ₂ CH ₂ O) _n -R ^3. R ³ is any of an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, or an unsaturated hydrocarbon group having 4 or more carbon atoms. (M is either a hydrogen atom, an alkali metal atom, an ammonium group, an organic ammonium group, or an organic amine group. If there are two M's, they may be different.)
[2] A ballpoint pen tip rotatably holding a silicon carbide ball is attached to the tip of the ink storage cylinder, either directly or via a connecting member, and the ink storage cylinder contains the carbonized silicon carbide ball of [1]. A water-based ballpoint pen refill filled with a water-based ink composition for a ballpoint pen having silicon-based balls.
[3] A water-based ballpoint pen in which the water-based ballpoint pen refill of [2] is disposed within the barrel.

According to the present invention, the coefficient of dynamic friction between the silicon carbide ball and the ball seat is reduced, the writing feeling is smooth, and a water-based ballpoint pen with excellent writing feeling can be formed. A water-based ink composition can be obtained.

[Water-based ink composition]
<Phosphate ester surfactant>
The water-based ink composition of the present invention includes:
Contains a phosphate ester surfactant represented by the following general formula (I) and having an HLB of 6 or more and an acid value of 120 or more.
(In the formula: n is an integer from 0 to 20. R ¹ is an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, or an unsaturated hydrocarbon group having 4 or more carbon atoms. ² is M or -(CH ₂ CH ₂ O) _n -R ^3. R ³ is any of an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, or an unsaturated hydrocarbon group having 4 or more carbon atoms. (M is either a hydrogen atom, an alkali metal atom, an ammonium group, an organic ammonium group, or an organic amine group. If there are two M's, they may be different.)

HLB can be calculated by the Kawakami method [HLB=7+11.7log(MW/MO), MW: sum of formula weights of hydrophilic moieties, MO: sum of formula weights of lipophilic moieties]. Alternatively, it may be determined through experiments or the like.
The lower limit of HLB is 6.0 or more, preferably 8.0 or more, more preferably 9.0 or more, and most preferably 10.0 or more. The upper limit of HLB is not particularly limited, but is, for example, 17.0 or less, preferably 15.0 or less, more preferably 14.0 or less.
If the HLB is less than 6.0, the ink composition tends to become unstable due to low solubility in the ink composition.

The acid value is the amount (mg) of potassium hydroxide required to neutralize 1 g, and can be determined by known means such as titration.
The lower limit of the acid value is 120 mgKOH/g or more, preferably 130 mgKOH/g or more, more preferably 150 mgKOH/g or more. The upper limit of the acid value is not particularly limited.

As such a phosphate ester surfactant, commercially available ones can be used. For example, selected from the Plysurf series (A210B, A208B) manufactured by Daiichi Kogyo Seiyaku Co., Ltd., the phosphanol series (ML-220, ML-240, ML-200, etc.) manufactured by Toho Chemical Industry Co., Ltd., and their salts. One or more types can be used.

The content of the phosphate ester surfactant is not particularly limited. For example, 0.01 to 10% by mass, preferably 0.05 to 5% by mass, more preferably 0.1 to 5% by mass, and even more preferably 0.1 to 1% by mass, based on the total amount of the ink composition. be.
If the content of the phosphate ester surfactant is less than 0.01% by mass, there is a risk that the writing quality will be poor. If it exceeds 10% by mass, it will tend to mix with the backflow stopper and may cause problems in terms of the stability of the ink composition over time.
When containing a salt of a phosphate ester surfactant, the proportion of the salt is preferably within the above range, or when containing both the salt and a phosphate ester surfactant, It is preferable that the proportion of their combined mass falls within the above range.

<Colorant>
The aqueous ink composition of the present invention may contain a coloring agent in order to provide handwriting with an aesthetic appearance and a desired tone. The colorant has properties such as good writing properties without blurring, good drying properties and cap-off properties, good sedimentation stability of the components in the ink, and excellent storage stability. If so, it can be used without any particular restriction.
The colorant is not particularly limited as long as it is used in an aqueous ink composition, particularly an ink composition for an aqueous ballpoint pen. One or more types selected from the group consisting of inorganic pigments, organic pigments, colored resin spheres, dyes, etc. that exhibit any color tone can be used.

Examples of inorganic pigments include carbon black, titanium oxide, zinc oxide, red iron oxide, yellow iron oxide, ultramarine, navy blue, metal powders such as aluminum powder and bronze powder, fluorescent pigments, glass flakes, pearl pigments, and glitter pigments. One or more types selected from the group consisting of the following can be used.
Examples of organic pigments include known colored pigments and fluorescent pigments such as phthalocyanine, azo, quinacridone, anthraquinone, dioxane, indigo, thioindigo, perinone, perylene, indolinone, and azomethine. One or more types selected from the group consisting of:
The colored resin spheres are spherical, amorphous, hollow, flat, etc. resin spheres colored with one or more types of inorganic pigments, organic pigments, or dyes exhibiting arbitrary color tones. Examples of the resin material forming the colored resin spheres include polyethylene, polypropylene, vinyl chloride, polymethacrylate, benzoguanamine, melamine resin, nylon, etc. The dye is preferably water-soluble, and includes direct dyes, acid dyes, Both food dyes and basic dyes can be used. For example, one or more types selected from the group consisting of anthraquinone-based, methine-based, carbonium-based, metal complex salt-based colored dyes and fluorescent dyes can be used.

When the aqueous ink composition of the present invention contains a colorant, it may be appropriately adjusted to obtain a desired color tone. For example, the content is 0.01 to 20% by mass, preferably 0.05 to 15% by mass, more preferably 0.1 to 10% by mass, and even more preferably 0.1 to 8% by mass based on the total amount of the ink composition. Can be done. If the content of the colorant is less than 0.01% by mass, a sufficient coloring effect may not be obtained (the color may be pale). If it exceeds 20% by mass, the solid content will increase, which may adversely affect fluidity, viscosity, handling, sedimentation stability, blurring of handwriting, manufacturing cost, etc. Note that the content of the colorant is not limited to these ranges, and may be appropriately selected depending on the type of colorant used. When the aqueous ink composition of the present invention contains a brightening agent, the amount of the brightening agent is not particularly limited, but may be, for example, 0.01 to 20% by mass.

<Water>
The aqueous ink composition of the present invention can contain water that functions as a dispersion medium and/or a solvent in order to disperse and/or dissolve the constituent components. As water, for example, tap water, purified water, distilled water, ion exchange water, and pure water can be used. Preferably, ion-exchanged water, distilled water, etc. are used.
The content of water is not particularly limited, and can be adjusted as appropriate depending on the content of each component in the ink composition, the viscosity of the ink composition, and the like. For example, when the water-based ink composition contains water, the amount is, for example, 1 to 90% by weight, preferably 10 to 80% by weight, more preferably 20 to 80% by weight, and still more preferably 50 to 70% by weight. be. If the water content is less than 1% by mass, there is a risk of smearing during writing and a decrease in storage stability. If it exceeds 90% by mass, sufficient coloring effect may not be obtained (the color may be pale).

<Other additives>
The aqueous ink composition of the present invention may contain other additives as necessary. Other additives are not particularly limited as long as they are used in ink compositions for water-based ballpoint pens.
Typical examples include viscosity modifiers (thickeners), wetting agents, and dispersants.
In addition, we also use preservatives such as benzisothiazoline preservatives, pentachlorophenol preservatives, cresol preservatives, propylene glycol preservatives, and iodine preservatives. agents), rust inhibitors (benzotriazole, tolyltriazole, dicyclohexylammonium nitrate, etc.), pH adjusters (alkali metal hydroxides (aqueous solutions) such as sodium hydroxide, potassium hydroxide, lithium hydroxide, triethanol, One or more types selected from amines, diethanolamine, monoethanolamine, dimethylethanolamine, morpholine, amine compounds such as triethylamine, ammonia (water), etc.) can be used.
In addition, dispersants, antifoaming agents, leveling agents, anti-aggregation agents, ultraviolet absorbers, infrared absorbers, antioxidants, non-thermochromic pigments, non-thermochromic dyes, optical brighteners, etc., as necessary. can be used in an appropriate amount.

(Viscosity modifier (thickener))
The aqueous ink composition of the present invention may contain a viscosity modifier (thickener) to adjust the viscosity. The viscosity modifier (thickener) is not particularly limited as long as it is used in aqueous ink compositions, particularly in aqueous ink compositions for ballpoint pens. For example, polysaccharides and their derivatives such as xanthan gum, welan gum, succinoglycan (reosan), diutan gum, guar gum, locust bean gum and their derivatives, cellulose polymers, cross-linked acrylic acid polymers, alkali-thickened acrylic One or more types selected from the group consisting of resins, urethane association thickeners, N-vinylacetamide resins, inorganic fine particles, etc. can be used.
When the water-based ink composition contains a viscosity modifier (thickener), the content is appropriately set so that the water-based ink composition has an appropriate viscosity depending on the application. For example, it can be in the range of 0 to 20% by weight, preferably 0.1 to 10% by weight, based on the total amount of the ink composition.

(wetting agent)
The aqueous ink composition of the present invention may contain a humectant to adjust drying properties and the like. The wetting agent is not particularly limited as long as it is used in aqueous ink compositions, particularly in aqueous ballpoint pen ink compositions. For example, glycols such as glycerin, diglycerin, triglycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol, polypropylene glycol, sugars, ureas, derivatives thereof, etc. One or more types selected from the group consisting of:
When the aqueous ink composition contains a wetting agent, it is appropriately set so that the drying properties and other properties of the ink composition become desired. For example, it can be in the range of 0.1 to 30% by weight, preferably 1 to 20% by weight based on the total amount of the ink composition.

(dispersant)
The aqueous ink composition of the present invention may contain a dispersant for the purpose of stabilizing the dispersion of pigments such as colorants contained therein. The dispersant has the effect of preventing precipitation of the pigment by stabilizing the pigment after being dispersed, and at the same time functions as a vehicle/binder for forming a coating film of the ink composition. The dispersant is not particularly limited as long as it is used in ink compositions, particularly ink compositions for water-based ballpoint pens, and commercially available ones can be used. For example, styrene-(meth)acrylic resin (emulsion), styrene-maleic acid resin (emulsion), styrene-maleic acid ester resin (emulsion), (meth)acrylic resin (emulsion), (meth)acrylic acid One or more types selected from the group consisting of ester resins (emulsions), cellulose compounds such as sodium carboxymethylcellulose, etc. can be used.
When the aqueous ink composition contains a dispersant, it can be contained in an amount of, for example, 0.1 to 30% by mass, preferably 1 to 10% by mass, based on the total amount of the ink composition. If the content exceeds 30% by mass, the dispersant may act as a flocculant and cause pigment aggregation. If the content is less than 0.1% by mass, pigment dispersion may not be sufficient and pigment aggregation may occur. When pigment aggregation occurs, pigment sedimentation occurs in the ink, and there is a possibility that ink flowability from the refill may deteriorate.

<Viscosity>
The viscosity of the aqueous ink composition of the present invention may be appropriately set, for example, from 1 to 100,000 mPa·s, preferably from 100 to 20,000 mPa·s, more preferably from 1,000 to 10,000 mPa·s (E type rotational viscometer (for example, TVE type viscometer manufactured by Toki Sangyo Co., Ltd., 3° R14 cone, 0.5 rpm)). If the viscosity of the water-based ink composition is less than 1 mPa・s, the flowability of the ink from the tip of the writing instrument (excessive water-based ink composition flows out during writing, making it impossible to form handwriting accurately), sedimentation stability, etc. This may cause problems. When the viscosity of the aqueous ink composition exceeds 100,000 mPa・s, the viscosity becomes too high, resulting in poor ink flowability from the tip of the writing instrument (ink does not flow out), ink handling properties, sedimentation stability, blurring of handwriting, etc. This may cause problems in terms of manufacturing costs, etc.

<pH value>
The pH of the aqueous ink composition of the present invention is not particularly limited, but is preferably 6 to 10. When the pH value approaches the acidic side of less than 6, the stability of the ink composition over time may deteriorate, and metal members that come into contact with the ink composition are likely to be corroded. When the pH value exceeds 10 and approaches the strong alkaline side, the ink composition tends to fade or discolor, and there is a risk that good handwriting may not be obtained.
Taking into particular consideration the stability over time, color development, writability, etc. of the ink composition, the pH value is preferably 7 to 9. As the pH value, for example, a value measured at 20° C. using a commercially available pH meter can be used.

<Ballpoint pen with silicon carbide ball>
The ballpoint pen having a silicon carbide ball of the present invention has a ballpoint pen tip rotatably holding a silicon carbide ball at the tip of an ink storage cylinder filled with an aqueous ink composition, either directly or through a connecting member. It has a water-based ballpoint pen refill attached.
Note that the water-based ink composition according to the present invention is used as a water-based ink composition for a ballpoint pen having the above-mentioned silicon carbide ball.

[Method for manufacturing water-based ink composition]
The method for producing the water-based ink composition of the present invention is not particularly limited, and any known method for producing a water-based ink composition can be used.
For example, by putting all the ingredients into a container and dispersing them by mixing and stirring with a device such as a ball mill, bead mill, roll mill, Henschel mixer, homomixer, propeller stirrer, homogenizer, high-pressure homogenizer, kneader, or dissolver, you can ink. can be created.
For example, some components such as water, colorant, phosphate ester surfactant, etc. are put into a container and mixed and stirred using the above-mentioned device to produce a dispersion liquid, and then the remaining components are Ink can be produced by adding ingredients, mixing and stirring.
When preparing an aqueous ballpoint pen ink composition, operations such as filtration, centrifugation, and defoaming may be performed to remove coarse particles, gas, and bubbles. When preparing the aqueous ink composition, it is also possible to employ means such as heating, cooling, pressurization, depressurization, and inert gas replacement. Furthermore, an aging step may be performed after the ink is produced.

[Refill]
The water-based ballpoint pen refill of the present invention rotatably holds an ink storage cylinder filled with an ink composition for a water-based ballpoint pen, and a silicon carbide ball attached directly or via a connecting member to the tip of the ink storage cylinder. Equipped with a ballpoint pen tip.
During writing, the water-based ballpoint pen ink composition flows out from the ink storage tube, adheres to the surface of the silicon carbide ball, and is transferred to the surface to be written on, such as paper, by the rotation of the silicon carbide ball, thereby making the writing process easier. It will be done.

The material constituting the ink storage cylinder is not particularly limited, and may include resins such as polypropylene, polyethylene, polyester, polyamide, polyurethane, and polyvinyl chloride, nickel-chromium alloy steel (SUS304 stainless steel), and chromium alloy steel. (SUS430 series stainless steel), austenitic stainless steel, free-cutting stainless steel, brass, aluminum, nickel silver, and phosphor bronze alloy.
Preferred examples include polypropylene, polyethylene, polyester, polyamide, nickel-chromium alloy steel (SUS304 stainless steel), chromium alloy steel (SUS430 stainless steel), austenitic stainless steel, brass, and nickel silver.

The material of the ball used in the ballpoint pen tip of the aqueous ballpoint pen refill of the present invention is a silicon carbide-based material. Specifically, examples include silicon carbide (SiC) and ceramics made of silicon carbide (SiC) and one or more of titanium nitride (TiN), zirconia (ZrO2), alumina ( _Al2O3 ), and the like _.
In the present invention, it is preferable to use balls made of silicon carbide (SiC).
The diameter of the ball is usually about 0.1 mm to 2.0 mm, and can be adjusted as appropriate depending on the purpose.

The ball seat used in the ballpoint pen tip of the aqueous ballpoint pen refill of the present invention is made of a material that has a lower hardness than the ball made of silicon carbide material. Specifically, examples include metal materials such as nickel silver, brass, and stainless steel, as well as resin materials such as polyoxymethylene, polyethylene terephthalate, polybutylene terephthalate, polyacetal, nylon, polyphenylene ether, and polyacrylate.

In the aqueous ballpoint pen refill of the present invention, the amount of ink flowing out can be adjusted as appropriate. Thereby, blurring of handwriting can be suppressed and good handwriting can be obtained.
Further, the movable amount (clearance) of the ball in the ballpoint pen tip in the vertical axis direction can be adjusted as appropriate depending on the amount of ink flowing out, and can be set to, for example, 20 to 50 μm.

The aqueous ballpoint pen refill of the present invention stores an aqueous ink composition in an ink storage cylinder, and is equipped with an ink follower made of base oil at the rear end to prevent backflow. The viscosity of the ink follower is, for example, 1000 to 10000 mPa·s.
The ink follower is a substance that can be accommodated in the refill, is incompatible with the aqueous ink composition filled in the ink storage cylinder, and has a small specific gravity with respect to the ink composition, and is a known substance. It can be used without any particular restrictions. Alternatively, the base oil may contain a thickener or the like.
As the base oil used for the ink follower, one or more types selected from polybutene, mineral oil, silicone oil, etc., which are insoluble or poorly soluble in water, can be used.
As the thickener, one or more types selected from, for example, particulate silica, calcium salts of phosphate esters, thermoplastic elastomers, etc. can be used. Furthermore, if necessary, for example, a thickening aid (clay thickener, metal soap, etc.), an ink follower followability improver (surfactant, etc.), an antioxidant, etc. can be included. Preferred examples include polybutene or a mixture of mineral oil and metal soap, and a mixture of silicone oil and silica.

[Water-based ballpoint pen]
The aqueous ballpoint pen of the present invention has the aqueous ballpoint pen refill disposed within the barrel, and the structure and shape of the ballpoint pen body are not particularly limited, and conventionally used ones can be applied.
Water-based ballpoint pens include retractable ballpoint pens that can house the pen tip in the barrel, such as knock-type, rotary, and sliding types, such as single-color, two-color, three-color, and four-color types; It can be a multifunctional type that can be combined with writing instruments other than ballpoint pens. Alternatively, it may be a cap-type ballpoint pen that includes a cap that covers the pen tip.
As the barrel and other members of the water-based ballpoint pen, known members may be used.

Further, the ballpoint pen having the silicon carbide ball of the present invention has a small dynamic friction coefficient/μk between the silicon carbide ball and the ball seat. Specifically, the coefficient of dynamic friction/μk between the silicon carbide ball and the ball seat is 0.267 or less, preferably 0.265 or less, and more preferably 0.263 or less. By setting the dynamic friction coefficient/μk within such a range, a ballpoint pen with a smooth writing feel can be obtained.
In addition, in the ballpoint pen of the present invention, the range of the dynamic friction coefficient/μk between the silicon carbide ball and the ball seat may be within such a range, and the type of the water-based ink composition is not particularly limited. Preferably, an aqueous ink composition containing a phosphate ester surfactant having an HLB and an acid value within a specific range can be used, whereby the dynamic friction coefficient/μk can be easily reduced.

The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to these Examples. In addition, unless otherwise specified, "%" means "% by mass" and "parts" means parts by mass.

[Aqueous ink composition constituents]
The following components were prepared as components of the water-based ink composition.
(solvent)
・Water: Ion exchange water (colorant)
・Pigment Black k7: CIPigment Black k7 (black pigment)
(thickener)
・Kelzan: Xanthan gum (product name manufactured by Sanshosha)
(Preservative)
・Proxel XL-2: (Product name manufactured by Lonza Japan)
(Fungicide)
・Courtside PH2: (Product name manufactured by Osaka Gas Chemical Co., Ltd.)
(wetting agent)
・Gly: Glycerin ・PG: Propylene glycol (rust preventive agent)
・BTA: Benzotriazole

(Phosphate ester surfactant)
・A219B: Pricesurf A219B (product name manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
HLB=16.2, acid value=51mgKOH/g
・PE510: Phosphanol PE-510 (trade name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=10.5, acid value=52mgKOH/g
・RS710: Phosphanol RS-710 (trade name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=13.3, acid value=62mgKOH/g
・RS610: Phosphanol RS-610 (trade name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=10.5, acid value=82mgKOH/g
・RS410: Phosphanol RS-410 (trade name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=9, acid value=105mgKOH/g
・RA600: Phosphanol RA-600 (product name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=11.7, acid value=110mgKOH/g
・ML240: Phosphanol ML-240 (trade name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=13.1, acid value=110mgKOH/g
・A210B: Pricesurf A210B (product name manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.)
HLB=9, acid value=123mgKOH/g
・ML220: Phosphanol ML-220 (trade name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=12.5, acid value=150mgKOH/g
・GF185: Phosphanol GF-185 (trade name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=5.2, acid value=158mgKOH/g
・GF199: Phosphanol GF-199 (trade name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=5.5, acid value=168mgKOH/g
・A208B: Pricesurf A208B (product name manufactured by Daiichi Kogyo Seiyaku Co., Ltd.)
HLB=6.6, acid value=173mgKOH/g
・ML200: Phosphanol ML-200 (trade name manufactured by Toho Chemical Industry Co., Ltd.)
HLB=10, acid value=202mgKOH/g

[Examples 1 to 5, Comparative Examples 1 to 8]
A water-based ink composition was prepared using the above components in the amounts (parts by mass) shown in Table 1 in the following manner.
Further, a water-based ballpoint pen was produced using the obtained water-based ink composition in the following manner.
(Method for producing water-based ink composition)
A mixed solution containing water and pigment was dispersed using a bead mill to obtain a pigment base.
Thereafter, components such as a solvent, a pigment base, and a lubricant were mixed using a stirrer and filtered through a mesh to prepare a water-based ink composition.
(Method for producing water-based ballpoint pen)
Prepare a plurality of SUS304 ink storage tubes with a silicon carbide ballpoint pen tip (ball diameter 1 mm) attached to one end, fill each with a certain amount of the obtained aqueous ink composition, and then use an ink backflow prevention method (gelling polybutene). A ballpoint pen refill was prepared. Next, a ballpoint pen refill was attached to the main body, a cap was attached, and then the air in the tube was removed using a centrifuge, and a tail plug was attached to obtain an aqueous ballpoint pen using each aqueous ink composition.
Using these water-based ballpoint pens, the water-based ink compositions were evaluated as follows. The results are also listed in Table 1.

<Dynamic friction coefficient/μk>
Using a surface property measuring device (manufactured by Shinto Kagakusha, Tribogear HEIDON-14DR), the dynamic friction coefficient/μk was measured by writing on high-quality paper under the following measurement conditions.
This dynamic friction coefficient can be said to substantially represent the dynamic friction coefficient between the silicon carbide ball and the ball seat.
Writing speed: 4,200mm/min
Writing distance: 70.0mm
Load converter capacity: 2,000gf
DSA amplifier range: 100%
Vertical load: 100g
Sampling speed: 1ms
Sampling capacity: 2,000 pieces

<Writing taste sensory evaluation>
Ten circles were drawn by hand on high-quality paper, and the feeling of the writing was sensory evaluated using the following evaluation criteria.
○: Smooth writing △: Slight smudge when writing ×: Slight smudge when writing

As is clear from the results of each example and comparative example, silicon carbide containing a phosphate ester surfactant represented by general formula (I) and having an HLB of 6 or more and an acid value of 120 or more. It can be seen that the water-based ink composition for a ballpoint pen having a ball-based ball has a small dynamic friction coefficient/μk, provides a smooth writing feel, and has an excellent sensory evaluation of writing taste.

Claims (3)

(a) A phosphate ester surfactant represented by the following general formula (I) and having an HLB of 6 or more and an acid value of 120 or more ,
(b) a colorant that is one or more selected from the group consisting of inorganic pigments, organic pigments, and dyes;
A water-based ink composition for a ballpoint pen having a silicon carbide ball containing (however,
In addition to removing the erasable water-based ink composition containing colored particles, which are particles that are colored by coloring the base material with a coloring agent, which has been subjected to the cleaning treatment, Excludes aqueous ink compositions containing colored particles, which are particles that are colored by coloring a base material with a coloring agent. ) .

(In the formula: n is an integer from 0 to 20. R ¹ is an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, or an unsaturated hydrocarbon group having 4 or more carbon atoms. ² is M or -(CH ₂ CH ₂ O) _n -R ^3. R ³ is any of an alkyl group having 1 or more carbon atoms, an aryl group having 6 or more carbon atoms, or an unsaturated hydrocarbon group having 4 or more carbon atoms. (M is either a hydrogen atom, an alkali metal atom, an ammonium group, an organic ammonium group, or an organic amine group. If there are two M's, they may be different.) A ballpoint pen tip rotatably holding a silicon carbide ball is attached to the tip of the ink storage cylinder, either directly or via a connecting member, and the silicon carbide ball according to claim 1 is mounted inside the ink storage cylinder. A water-based ballpoint pen refill filled with a water-based ink composition for a ballpoint pen having a ball. An aqueous ballpoint pen comprising the aqueous ballpoint pen refill according to claim 2 disposed within a barrel.