JPS6115108B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an ink for writing instruments in which pigments are dispersed, and its purpose is to have excellent dispersibility of pigments over time, that is, when stored or unused, and to provide excellent dispersibility of pigments when writing on paper.
The object is to provide an ink for writing instruments whose handwriting has excellent durability (water resistance, fixability). Conventionally, this type of ink for writing instruments has been known as, for example, drafting ink, but this ink is made by dispersing pigments such as carbon black and aniline black in a solution using a thickening agent such as polyvinyl alcohol and an appropriate dispersing agent. The idea was to disperse it in a stable state. However, when polyvinyl alcohol is used as a sizing agent, if the amount used is increased, an ink with excellent dispersion stability over time can be obtained, but on the other hand, the viscosity increases, making it difficult to use as an ink for writing instruments. . Further, when a low molecular weight material is used to maintain a low viscosity, there is a problem that the water resistance and fastness of handwriting, such as fixability, are insufficient. Therefore, the inventors of the present invention conducted various studies to see if it was possible to solve the problems of inks using polyvinyl alcohol without sacrificing the advantages of polyvinyl alcohol, and found that it would be possible to solve the problems of inks using polyvinyl alcohol. The invention has been completed, and in the ink in which pigments are dispersed, polyvinyl alcohol, 2% of the weight of the polyvinyl alcohol
The gist of this invention is an ink for writing instruments containing up to 20% by weight of an acrylic ester and/or methacrylic ester adduct of polyethylene glycol represented by the following structural formula 1. (In the formula, R ₁ represents hydrogen, a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer of 5 to 10.) In the present invention, acrylic ester of polyvinyl alcohol and polyethylene glycol and/or methacrylic acid It is not clear why the solidity of handwriting improves when ester adducts are used together, but as shown below, polyethylene glycol acrylic ester and/or
This is thought to be because the methacrylic acid ester adduct crosslinks polyvinyl alcohol. The acrylic ester and/or methacrylic ester adduct of polyethylene glycol used in the present invention has low odor and is stable over time when used in ink, unlike aldehydes that are commonly used as crosslinking agents for polyvinyl alcohol. It has the advantage of being superior to The amount of this additive used is in the range of 2 to 20% by weight based on the weight of polyvinyl alcohol used as a glue, and if it is less than 2% by weight, problems such as insufficient solidity of handwriting may occur. If the amount is more than 20% by weight, there will be no effect of the addition, and on the contrary, the ink will thicken over time and become unstable, which is not preferable. The appropriate amount of polyvinyl alcohol to be used is 2 to 7.5% by weight based on the total ink. In addition, carbon black, aniline black, phthalocyanine black, etc. can be used as pigments, and powders and aqueous pigment dispersions are appropriately used, and the amount used is based on the total ink. A suitable range is 5 to 15% by weight. Furthermore, the ink solvent is mainly water, and in addition, polyhydric alcohols such as ethylene glycol, diethylene glycol, propylene glycol, glycerin, and thiodiethylene glycol, ethylene glycol monoalkyl ethers such as methyl cellosolve and ethyl cellosolve, methyl carbitol, and ethyl. Diethylene glycol monoalkyl ether such as carbitol and lower alcohols such as ethanol, propanol and butanol are used alone or in combination,
The appropriate amount to be used is 2 to 15% by weight based on the total ink. In addition to the above-mentioned polyvinyl alcohol, water-soluble natural polymer substances and synthetic polymer substances can be used as a sizing agent, and ordinary pigment dispersants, preservatives, etc. can also be used depending on the purpose. can be used. Methods for preparing ink using the above-mentioned composition include a pole mill, roll mill, sand mill, vibration mill, Chemistler, homomixer, or ultrasonic dispersion method, which are generally used for pigment dispersion. The pigment may be selected by considering the following factors, and the pigment may be dispersed in the liquid. Hereinafter, the present invention will be explained with reference to Examples. "Example Middle" indicates parts by weight. Example 1

[Table] Add the above mixture to glass beads with a diameter of 1.5 to 2 mm.
Pour 100g into a 500ml stainless steel vessel and use a sand grinder.
The mixture was stirred and dispersed at 1500 RPM for 2 hours to obtain an ink. Example 2

[Table] The above formulation except Aquatex 650 was stirred and mixed, and then Aquatex 650 was gradually added while stirring to obtain an ink. Example 3

【table】

[Table] An ink was obtained from the above formulation using the same dispersion method as in Example 1. Comparative Example An ink was obtained using the composition of Example 1 except that the triethylene glycol methyl methacrylate adduct was removed. The properties of the inks obtained in the above examples and comparative examples were as shown in Table 1.

[Table] As described above, the ink for writing instruments of the present invention has excellent dispersion stability and solidity of handwriting (fixability, water resistance).

Claims (1)

[Scope of Claims] 1. In an ink in which a pigment is dispersed, polyvinyl alcohol, an acrylic ester of polyethylene glycol represented by the following structural formula 1 and/or methacrylic acid in an amount of 2 to 20% by weight based on the weight of the polyvinyl alcohol. An ink for writing instruments containing an ester adduct. (In the formula, R ₁ represents hydrogen or a methyl group, R ₂ represents a methyl group or an ethyl group, and n represents an integer from 5 to 10.)