JPH0123512B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a water-based ink for writing instruments that uses a pigment as a coloring agent. More specifically, the present invention relates to a water-based ink for writing instruments that uses a pigment as a coloring agent. The present invention relates to a water-based pigment ink for writing instruments having dispersibility. (Prior art and its problems) As a writing instrument using a conventional metal tip,
There are water-based metal ballpoint pens that use water-based inks consisting of dyes and water-based media, but because they use dyes, they have poor light fastness and water resistance, so water-based pigment inks using pigments have been proposed. Summer. However, since the pigment of the coloring agent used in water-based pigment ink is insoluble in the solvent, the first point of water-based pigment ink is how to make the pigment into fine particles and stably disperse it. The main point is that if a writing instrument with a metal tip is filled with water-based pigment ink, the dispersion will be broken due to corrosion of the metal tip and the pigment will coagulate, making it impossible to write smoothly and causing blurred or impossible writing lines. Benzotriazole is generally used as an effective rust inhibitor to prevent this corrosion, but in the case of water-based pigment inks, benzotriazole is poorly soluble in aqueous media, and the required amount of benzotriazole is It may become adsorbed to pigment particles and become ineffective as a rust preventive. For this reason, easily soluble benzotriazole in the form of an amine salt has a high pH and destabilizes the dispersion system of water-based pigment inks, resulting in agglomeration of pigment particles and impeding storage of writing instruments and smooth writing. Furthermore, condensates of oleic acid and benzotriazole cannot be used in aqueous pigment inks because they are insoluble in water. (Means for Solving the Problems) The present invention was developed as a result of intensive research to solve the above-mentioned problems, and the search for the most suitable rust preventive agent for water-based pigment ink revealed that it was itself water-soluble and could be dispersed in the ink. The present invention was achieved by discovering a rust preventive agent that does not impair properties. That is, the present invention provides a water-based pigment ink for writing instruments comprising a pigment, a dispersant, and an aqueous medium, which is characterized in that a benzotriazole derivative represented by the following general formula () is added as a rust preventive agent. The main points are as follows. general formula (In the formula, R is hydrogen, a methyl group, an ethyl group, an amino group, a methoxy group, an ethoxy group, and a halogen.) (Structure of the Invention) Next, the present invention will be explained in detail. As the coloring agent used in the present invention, conventionally known inorganic pigments and organic pigments can be used, and their forms such as powder and aqueous paste can be used without any problem. The amount of these pigments used is preferably 3 to 20% by weight based on the total amount of the ink. Next is the dispersant, as a water-soluble polymer,
Homopolymers of acrylic acid, methacrylic acid, styrene sulfonic acid, maleic acid, itaconic acid, N-vinylpyrrolidone, etc., or copolymers with acrylic acid alkyl esters, methacrylic acid alkyl esters, styrene, vinyl acetate monomers, etc. can be used. If necessary, anionic activators such as long-chain acylated amino acids, alkylbenzenesulfonic acids, alkylsuccinic acids, sulfates, long-chain fatty acid ammonium and alkanolamine salts, alkylphenol/ethylene oxide adducts, alkyl alcohol/ethylene Nonionic surfactants such as oxide adducts, sorbitan mono, difatty acid esters, and ethylene oxide adduct alkylamines can be optionally used in combination. The aqueous medium that can be used in the present invention is mainly water, but if necessary, nonvolatile water-soluble organic solvents such as ethylene glycol, diethylene glycol, propylene glycol, and glycerin can be used. 30% by weight is desirable. The water-soluble rust inhibitor, which is the essence of the present invention, is produced by applying a Mannitz reaction to the corresponding benzotriazole.
-oxyethyl)aminomethyl group is introduced. The reaction formula is as follows. (R is hydrogen, methyl group, ethyl group, amino group,
They are methoxy group, ethoxy group and halogen. ) For example, a derivative of the general formula in which R is a 4-methyl group can be easily obtained by the following reaction operation.
That is, 0.26 mol of diethanolamine and 0.26 mol of 4-methylbenzotriazole are heated to 80 to 85°C to form a homogeneous solution. Next, stir at 70-75℃ for 1 hour. Next, 35% formalin 0.26 while cooling with water.
The Mannich reaction product of 4-methylbenzotriazole is obtained in the form of a solution by adding 4-methylbenzotriazole and stirring for 1 hour at 70-75°C. It is optionally dissolved in water or other aqueous media and does not precipitate crystals even when cooled. Corresponding derivatives can be readily obtained using other substituted benzotriazoles. The amount used can be 0.05 to 10% by weight based on the total amount of ink. In addition, hygroscopic substances such as urea and urea derivatives, antifungal agents, and the like can be optionally used as necessary. The aqueous pigment ink for writing instruments of the present invention is composed of the above-mentioned components, and can be produced by mixing and grinding using a dispersing machine such as a ball mill, homomixer, sand grinder, speed line mill, or roll mill. easily obtained. The water-based pigment ink for writing instruments of the present invention obtained as described above has sufficient stability both as an ink alone and in a writing instrument, but it also corrodes the arrow grooves of metal chips and metal balls in forced aging tests. Since there is nothing to do, smooth writing is possible at all times. (Example) Next, the present invention will be specifically explained with reference to Examples, where "parts" in the examples represent "parts by weight." Example 1 Styrene-methacrylic acid copolymer (mole ratio 3:
Monoethanolamine salt of 2) 10 parts Ethylene glycol 30 parts Carbon black (manufactured by Mitsubishi Kasei Corporation: MA-100)
10 parts nonionic activator (manufactured by Kao Atlas Co., Ltd.: Tween 61) 2 parts 4-methylbenzotriazole derivative (R in the above general formula () is a 4-methyl group) 1 part water 47 parts Add the above ingredients to a ball mill. distributed for 100 hours,
Pigment content is removed by centrifuging coarse pigment particles.
A 7.5% by weight black water-based pigment ink for writing instruments was obtained. Comparative Example 1 A black aqueous pigment ink for writing instruments was obtained by using the same amount of 4-methylbenzotriazole instead of the 4-methylbenzotriazole derivative used in Example 1. Example 2 Ammonium salt of styrene-maleic anhydride copolymer (mole ratio 2:1) 8.5 parts ethylene glycol 15 parts propylene glycol 5 parts Copper phthalocyanine blue (manufactured by Toyo Ink Co., Ltd.:
Lionol Blue SM) 9-part benzotriazole derivative (general formula ()
(R is hydrogen) 2 parts Sodium Omazine (mold inhibitor) 0.5 parts Water 60 parts After treating the above ingredients with a sand grinder for 10 hours, coarse particles were removed to create a blue writing instrument with a pigment content of 7% by weight. A water-based pigment ink was obtained. Comparative Example 2 Instead of the benzotriazole derivative used in Example 2, the same amount of benzotriazole-monoethanolamine salt (made by humidifying benzotriazole and monoethanolamine) was used to prepare a blue water-based pigment ink for writing instruments. Obtained. Example 3 Monomethylamine salt of butyl methacrylate-acrylic acid copolymer (molar ratio 1:1) 15 parts Ethylene glycol 20 parts 5-methoxybenzotriazole derivative (R in the above general formula () is a 5-methoxy group) 1 part Glycerin 5 parts Copper phthalocyanine green (Sumika Color Co., Ltd.)
(manufactured by: Cyanine Green 404SA, solid content 50% by weight) 20 parts water 39 parts The above components were dispersed in a roll mill and coarse particles were removed to obtain a green water-based pigment ink for writing instruments with a pigment content of 8.5% by weight. Comparative Example 3 Instead of the 5-methoxybenzotriazole derivative of Example 3, the same amount of a condensate of 5-methoxybenzotriazole and oleic acid was used to obtain a green aqueous pigment ink for writing instruments. (Effects of the Invention) Each of the aqueous pigment inks of Examples 1 to 3 and Comparative Examples 1 to 3 was evaluated by the following test method. 1 Single ink test at 90°C Place 5 ml of ink in a screw vial with an internal volume of 20 ml, seal the vial, and observe the change after 1 hour at 90°C.

[Table] 2 Test at 50°C with a writing instrument 1 Fill a metal ballpoint pen with a Shinchiyu tip and a carbide ball with each water-based pigment ink, place it in a constant temperature bath at 50°C, and measure the number of days until writing becomes impossible. Measure. 2 Similarly, observe the presence or absence of corrosion inside the metal chip using a stereomicroscope.

【table】

[Table] As described above, the water-based pigment ink for writing instruments of the present invention has excellent pigment dispersibility and corrosion resistance to metals.

Claims (1)

[Scope of Claims] 1. A water-based pigment ink for writing instruments comprising a pigment, a dispersant, and an aqueous medium, characterized in that a benzotriazole derivative represented by the following general formula () is added as a rust preventive agent. Water-based pigment ink. general formula (In the formula, R is hydrogen, methyl group, ethyl group, amino group, methoxy group, ethoxy group, and halogen.)