JPH11158433A - Aqueous ink composition for ballpoint pens - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To ensure good ink ejection by minimizing wear of a ball seat due to rotation of a ball,
Provided is an ink composition for an aqueous ball-point pen capable of long-range writing. SOLUTION: An aqueous ballpoint pen ink composition containing at least a coloring material, a water-soluble organic solvent and water, wherein a salt of carboxyethylthiosuccinic acid is added in an amount of 0.5 to 10% by weight based on the total weight of the aqueous ballpoint pen ink composition. % Content.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ball-point pen, in which the wear of the ball seat due to the rotation of the ball is prevented as much as possible, thereby ensuring good ink dischargeability and enabling long-distance writing. The present invention relates to an aqueous ink composition for use.

[0002]

2. Description of the Related Art Conventionally, an ink for a water-based ballpoint pen is composed of a coloring material, a water-soluble organic solvent and water, and has a viscosity of several cp (25 ° C.) or several thousands to tens of thousands, depending on the structure of the ballpoint pen used. cp (25 ° C.) is known.
Those with a few cp are mainly used for a structure using batting as an ink occluding body, and those with several thousand to tens of thousands cp are mainly used for a structure using a hollow cylinder as an ink occluding body. The ballpoint pen using the water-based ink has a problem in that the ink is insufficiently ejected during use and the handwriting is blurred, so that smooth writing cannot be performed and the writing distance is shortened. In order to solve this problem, attempts have been made to increase the lubricity of the ink by adding a water-soluble cutting oil or a lubricating oil to the ink.

[0003]

The cause of the shortage of the writing distance due to insufficient ink ejection and blurring of the handwriting to shorten the writing distance is as follows. Ball sinking, which is a phenomenon in which the ink flow grooves in the inside are closed by balls. This problem is particularly problematic when the viscosity is in the range of thousands to tens of thousands cps (25
° C), but several cps (2
(5 ° C.) also occurred after long-term use.

An object of the present invention is to provide an ink composition for a water-based ball-point pen, which ensures good ink ejection by minimizing abrasion of a ball seat due to rotation of a ball and enables long-distance writing. That is.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and has at least a coloring agent, a water-soluble organic solvent, a salt of carboxyethylthiosuccinic acid and water. The gist of the invention is a water-based ink composition for a ballpoint pen.

Hereinafter, the present invention will be described in detail. The coloring material and the water-soluble organic solvent used in the present invention are not different from the components of the conventionally known aqueous ballpoint pen ink composition. Hereinafter, an example is shown. As the coloring material, pigments and / or dyes can be used. Examples of the pigment include organic pigments such as azo pigments, condensed polyazo pigments, phthalocyanine pigments, quinacridone pigments, indigo pigments, and thioindigo pigments, and inorganic pigments such as carbon black, navy blue, red iron oxide, and titanium oxide. In addition, an aluminum powder for producing a metallic tone and a pearl pigment for producing a pearl tone can be used. Dyes are acid dyes, direct dyes,
Water-soluble dyes such as basic dyes can be used. The above coloring materials can be used alone or in combination.

The water-soluble organic solvent is used for the purpose of improving quality stability such as prevention of freezing at a low temperature required for ink and prevention of drying at a pen tip. Specifically, glycols such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, polyethylene glycol, 3-butylene glycol, thiodiethylene glycol, glycerin, ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, 2-pyrrolidone, and triethanol An amine or the like can be used alone or in combination. The amount used is preferably 5 to 30% by weight based on the total amount of the ink.

The carboxyethylthiosuccinic acid salt, which is the gist of the present invention, is used to prevent wear of the ball seat. Specifically, lithium carboxyethyl thiosuccinate, potassium carboxyethyl thiosuccinate, salts of alkali metals such as sodium carboxyethyl thiosuccinate and ammonium carboxyethyl thiosuccinate,
Examples include salts of amines such as ethanolamine carboxyethylthiosuccinate, diethanolamine carboxyethylthiosuccinate, and triethanolamine carboxyethylthiosuccinate. The amount used is 0.5 to 10% by weight based on the total weight of the water-based ink composition for ballpoint pens.
Is preferred. If it is less than 0.5% by weight, it is difficult to obtain a desired lubricating effect in the ballpoint pen tip, and if it exceeds 10% by weight, other quality may be deteriorated.

Water is used as the main solvent.

When the ink is directly filled into the ink container, a viscosity modifier is used for the purpose of regulating the viscosity of the ink. More preferably, the viscosity modifier exerts its effect with a small amount of addition. Specifically, synthetic (co) polymers such as polyvinylpyrrolidone, polyethylene oxide, polyacrylate, methyl vinyl ether / maleic anhydride copolymer, and cellulose-based polymers such as sodium carboxymethylcellulose, hydroxypropylcellulose, and hydroxylpropylmethylcellulose. Molecules,
In addition to natural polymers such as guar gum, xanthan gum, welan gum, ramzan gum, locust bean gum, and the like, gelling agents such as hydrogenated castor oil and polycarboxylic acid amide can be mentioned. These viscosity modifiers can be used alone or as a mixture.

When a pigment, aluminum powder, pearl pigment, or the like is used as a coloring material, a binder is used to fix a coating film of the ink on the paper surface. Specifically, an alkali metal salt, an amine salt, an ammonium salt of a styrene-acrylic acid copolymer, an alkali metal salt, an amine salt, an ammonium salt, a styrene-acrylic acid ester of an α-methylstyrene-acrylic acid copolymer In addition to alkali metal salts, amine salts and ammonium salts of acrylic acid copolymers,
Examples include water-insoluble resins such as acrylic resins, vinyl acetate resins, and styrene-butadiene copolymers.
The water-insoluble resin is used in the form of an aqueous emulsion. The amount used is preferably 3 to 20% by weight based on the total amount of the ink composition for aqueous ballpoint pens.

[0012] In addition to the above components, various additives used in aqueous inks for writing instruments can be used as needed. For example, sugar alcohols such as sorbitol and xylitol to prevent evaporation of ink, humectants such as urea, ethylene urea, and thiourea, benzothiazoline-based, omazine-based preservatives, and rust-preventive agents such as benzotriazole, Surfactants and the like.

For producing the water-soluble ink composition for a ball-point pen of the present invention, various methods can be adopted. For example, the above components are blended and mixed and stirred by a stirrer, or a ball mill, a sand grinder, a speed line, or the like. It can be easily obtained by mixing and dispersing with a dispersing machine such as a mill or a three roll.

[0014]

The free-cutting alloy is used for the tip of the ballpoint pen because precision machining is required. Free cutting alloys include ferrite or martensitic stainless steel, nickel silver, brass, and the like, and tungsten carbide (carbide alloy) is mainly used as a ball material. The salt of carboxyethylthiosuccinic acid is present on the surface of the ball and the ball seat with the sulfur atom in the molecule adsorbed on the iron or copper in the alloy and the hydrophobic group facing away from the adsorption surface. At this time, the hydrophobic groups face each other between the ball and the ball seat, and the repelling force generated there plays a cushion-like role, so that a lubricating effect is obtained. As a result, it is considered that the wear of the ball seat is reduced, so that the sinking of the ball can be suppressed, and good ink ejection properties are exhibited until the ink is used up.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a detailed description will be given based on embodiments. Example 1 C.I. I. Acid Black 2 (colorant) 10.0 parts by weight Propylene glycol 10.0 parts by weight Ethylene glycol 10.0 parts by weight Sodium carboxyethylthiosuccinate 2.0 parts by weight Benzotriazole 0.4 parts by weight Water 67.6 parts by weight The above components were mixed and stirred with a stirrer for 3 hours to obtain a black ink.

Example 2 Carbon black (coloring material) 10.0 parts by weight Ethylene glycol 15.0 parts by weight Glycerin 5.0 parts by weight Potassium carboxyethylthiosuccinate 3.0 parts by weight Guar gum 0.5 parts by weight Styrene-acrylic Ammonium salt of acid copolymer (Johncryl 62, manufactured by Johnson Polymers Co., Ltd.) 5.0 parts by weight Water 61.5 parts by weight Components other than guar gum and potassium carboxyethylthiosuccinate in the above components were mixed, After performing a dispersion treatment in a ball mill for 24 hours, guar gum and potassium carboxyethylthiosuccinate were added and the dispersion treatment was performed again for 3 hours, and coarse particles were removed with a filter or the like to obtain a black ink.

Example 3 Titanium oxide (Kronos KR380, manufactured by Titanium Industry Co., Ltd.) 30.0 parts by weight Fluorescent pigment (LUMIKOL NKW2108, manufactured by Japan Fluorescent Co., Ltd.) 12.0 parts by weight Ethylene glycol 3.0 parts by weight Glycerin 3.0 parts by weight Ammonium carboxyethylthiosuccinate 2.0 parts by weight Xanthan gum 0.5 parts by weight Ammonium salt of styrene-acrylic copolymer (Johncryl 61J, manufactured by Johnson Polymer Co., Ltd.) 6.0 parts by weight POE (20) Sorbitan monococonut oil ester (TL10, manufactured by Nikko Chemicals Co., Ltd.) 1.0 part by weight Water 42.5 parts by weight Among the above components, each component other than the fluorescent pigment, xanthan gum, and ammonium carboxyethylthiosuccinate was used. After mixing and performing a dispersion treatment with a ball mill for 24 hours, a fluorescent pigment, Santangamu, it was stirred for 1 hour added carboxyethylthio ammonium succinate to yield a milky sky blue ink.

Example 4 Aluminum paste (WXM0630, manufactured by Toyo Aluminum Co., Ltd.) 10.0 parts by weight Ethylene glycol 7.5 parts by weight Glycerin 7.5 parts by weight Sodium carboxyethylthiosuccinate 5.0 parts by weight Xanthan gum 1. 0 parts by weight Acrylic emulsion (John Krill J450, manufactured by Johnson Polymer Co., Ltd.) 8.0 parts by weight Sugar alcohol (PO20, solid content 75%, manufactured by Towa Kasei Kogyo Co., Ltd.) 2.0 parts by weight POE (15) Nonylphenyl ether (NP15, manufactured by Nikko Chemicals Co., Ltd.) 1.0 part by weight Water 58.0 parts by weight Among the above components, components other than xanthan gum are mixed,
After performing a dispersion treatment with a homogenizer for 10 minutes, xanthan gum was added and stirred for 1 hour to obtain a silver ink.

Example 5 Aluminum paste (WXM0630, manufactured by Toyo Aluminum Co., Ltd.) 10.0 parts by weight Titanium oxide (Titanics JR800, manufactured by Teika Co., Ltd.) 10.0 parts by weight Fluorescent pigment (LUMIKOL NKW2167, Nippon Fluorescent ( 4.0 parts by weight Ethylene glycol 8.0 parts by weight Glycerin 8.0 parts by weight Potassium carboxyethyl thiosuccinate 5.0 parts by weight Xanthan gum 0.7 parts by weight Ammonium salt of styrene-acryl copolymer (John) Kuril J-61J, manufactured by Jung Son Polymer Co., Ltd. 10.0 parts by weight POE (20) Sorbitan monococonut oil ester (TL10, manufactured by Nikko Chemicals Co., Ltd.) 1.0 part by weight Water 43.3 parts by weight Water Each of the above components Medium, aluminum paste, fluorescent pigment, xanthan gum, carboxyethyl thioha The components excluding potassium citrate were mixed and subjected to a dispersion treatment with a ball mill for 24 hours. Then, an aluminum paste, a fluorescent pigment, xanthan gum, and potassium carboxyethylthiosuccinate were added, and the mixture was stirred for 1 hour to give a metallic gloss. A magenta ink was obtained.

Comparative Example 1 An ink was obtained in the same manner as in Example 1 except that water was added instead of sodium carboxyethylthiosuccinate.

Comparative Example 2 An ink was obtained in the same manner as in Example 2 except that water was added instead of potassium carboxyethylthiosuccinate.

Comparative Example 3 An ink was obtained in the same manner as in Example 5, except that water was added instead of potassium carboxyethylthiosuccinate.

As described above, the inks obtained in Example 1 and Comparative Example 1 were applied to a commercially available water-based metal ballpoint pen (Super Ball BH16, manufactured by Pentel Co., Ltd.) in which the ink absorbing material was batting.
5 g was filled and a writing test was performed. Example 2 and Comparative Example 2
The ball-point pen tip (ball diameter: 0.
5 mm, material: tungsten carbide) is directly filled with 0.8 g into the cylinder of a ballpoint pen fitted with one end of a polypropylene cylinder, and 0.1 g of the ink backflow prevention body is filled with the other end of the cylinder. After the bubbles were centrifugally degassed, a writing test was performed. Using the inks obtained in Examples 3 to 5 and Comparative Example 3, a ballpoint pen tip (ball diameter: 0.8 mm, material:
0.8 g of silicon carbide) is directly filled into a ball-point pen cylinder fitted into one end of a polypropylene cylinder, and the other end of the cylinder is filled with 0.1 g of an ink backflow preventer. After noticing, a writing test was performed. Table 1 shows the results.

[0024]

[Table 1]

Writing conditions: writing speed: 7 cm / sec, writing angle: 70 ° Writing load: 100 g Writing paper: high-quality paper (JIS P3201 writing paper A) Ball sinking (μm) = Ball before writing—at the end of writing Ink consumption rate of ball out (%) = (weight of ballpoint pen before writing−weight of ballpoint pen at end of writing) / weight of ballpoint pen before writing × 10
0 Handwriting skip: The presence or absence of a break in the writing line was visually confirmed.

[0026]

As described in detail above, the water-based ink composition for ball-point pens according to the present invention can be used for a long period of time by minimizing wear of the ball seat due to rotation of the ball. It is an excellent material that ensures the ink ejection property and allows the ink to be used up to the end.

Claims (1)

[Claims] 1. An aqueous ballpoint pen ink composition comprising at least a coloring agent, a water-soluble organic solvent, a salt of carboxyethylthiosuccinic acid, and water.