JPH0564194B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a water-based pigment ink, and more particularly to a water-based pigment ink that has excellent ink discharge properties and pen tip drying resistance. (Prior art) Dye-type inks have traditionally been used as water-based inks for writing instruments such as felt-tip pens, felt-tip pens, ballpoint pens, and calligraphy pens, recorders, wire dot printers, inkjet printers, and other items with pen nibs. Although these dye inks have been widely used, they are insufficient in terms of light resistance and water resistance, and in recent years, the use of pigment-type inks has become more prominent. (Problems to be Solved by the Invention) However, although pigment inks have excellent light fastness and water resistance, they have problems such as inferior ink ejection compared to dye inks, and ink that dries easily at the pen tip. have. Therefore, attempts have been made to add various surfactants and lower alcohols to improve the ink discharge rate, but these have adverse effects on other ink properties such as bleeding and a decrease in water resistance, and furthermore, they have a negative effect on pigment dispersibility. There is a problem in that it becomes unstable and causes sedimentation and agglomeration of the pigment, resulting in clogging of the pen tip, etc. In addition, attempts have been made to add various anti-drying agents such as glycol-based, polyhydric alcohol-based, and urea-based agents to improve the drying resistance of the pen nib, but if they are added in sufficient amounts to obtain a sufficient effect, the ink There was a problem in that the viscosity of the ink increased and the amount of ink discharged decreased significantly. (Means for solving the problem) Therefore, the inventors of the present invention conducted extensive research in order to obtain a water-based pigment ink with excellent ink ejection properties and pen tip drying resistance without degrading other ink properties. As a result, it was discovered that sufficient effects can be obtained by using trimethylpentanediol monoisobutyrate (including all isomers), and the present invention has been completed. That is, the gist of the present invention is an aqueous pigment ink comprising at least a pigment, a dispersant, water, and trimethylpentanediol monoisobutyrate. (Function) It is not clear why the aqueous pigment ink of the present invention has excellent ink discharge properties and pen tip drying resistance, but it is speculated as follows. Trimethylpentanediol monoisobutyrate (including all isomers) is adsorbed on the surface of the dispersant such as resin and/or surfactant attached to the surface of the pigment particles in the aqueous pigment ink of the present invention, and the pigment particles are separated from each other. It is thought that the slippage becomes better, and as a result, the ink discharge performance improves. In addition, since trimethylpentanediol monoisobutyrate (including all isomers) itself is a non-volatile substance, it prevents the pigment surface from drying and also suppresses the drying of the entire ink, improving pen tip drying resistance. It seems that it will. (Structure of the Invention) Next, each component of the present invention will be explained. Pigments are used as coloring materials, and various known pigments can be used. Specific examples include azo pigments, condensed polyazo pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, and dioxazine pigments. , indigo pigments, thioindigo pigments, perinone, perylene pigments, inorganic pigments such as titanium oxide, iron oxide, carbon black, and fluorescent pigments. As the dispersant, all commonly used dispersants for pigments such as resins and surfactants can be used. Trimethylpentanediol monoisobutyrate is used to improve ink ejection properties and pen tip drying resistance, and there are several isomers.
All can be used, but among them 2, 2, 4-
Trimethylpentanediol-1,3-monoisobutyrate exhibits excellent effects, and the amount used is 0.01 to 5% by weight based on the total amount of ink.
is preferred. Water is used as a solvent. In addition to the above ingredients, if necessary, glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, low molecular weight polyethylene glycol, urea,
Known wetting agents and anti-freezing agents such as ethylene urea, thiourea or their derivatives, additives such as amines, alcohols, ethers and esters, preservatives, fungicides, rust preventives, alkalis. It is also possible to use various additives such as additives, dyes for complementary colors, etc. Various methods can be adopted as a method for manufacturing the aqueous pigment ink of the present invention, and one example is as follows.
It is obtained by blending the above-mentioned components and mixing and grinding the mixture using a conventionally known dispersing machine such as a ball mill homomixer, a sand grinder, a spit line mill, or a roll mill. (Example) The present invention will be described in more detail based on the following examples, where "parts" in the examples indicate "parts by weight." Example 1 Carbon black 12.0 parts Styrene-acrylic acid amine salt (dispersant)
4.5 parts ethylene glycol 25.5 parts 2,2,4-trimethylpentanediol
1,3-monoisobutyrate 1.0 parts Water 56.8 parts Proxel CRL (preservative, manufactured by I, C, I)
0.2 parts Except for 2,2,4-trimethylpentanediol-1,3-monoisobutyrate in the above ingredients,
After blending other ingredients and dispersing in a ball mill, adding 2,2,4-trimethylpentanediol-1,3-monoisobutyrate and dispersing again, filter etc. Coarse particles were removed to obtain a black water-based pigment ink. Comparative Example 1 A black water-based pigment ink was prepared in the same manner as in Example 1 except that 2,2,4-trimethylpentanediol-1,3-monoisobutyrate in Example 1 was removed and water was added in the same amount. Obtained. Example 2 Copper phthalocyanine blue 10.5 parts Styrene - ammonium salt of maleic acid (dispersant) 5.5 parts Diethylene glycol 21.5 parts Urea 5.0 parts 2,2,4-trimethylpentanediol
1,3-monoisobutyrate 1.0 parts Water 56.3 parts Proxel BD (preservative, manufactured by I, C, I)
0.2 parts A blue aqueous pigment ink was obtained using the above ingredients in the same manner as in Example 1. Comparative Example 2 A blue water-based pigment ink was obtained in the same manner as in Example 2, except that 2,2,4-trimethylpentanediol-1,3 monoisobutyrate of Example 2 was removed and water was added in the same amount. Ta. Example 3 Watching lead 10.5 parts Styrene-maleic acid amine salt (dispersant)
4.0 parts Glycerin 22.5 parts Butyl glycol (distributor: Nagase Sangyo Co., Ltd., ethylene glycol monobutyl ether) 1.5 parts 2,2,4-trimethylpentanediol
1,3-monoisobutyrate 0.8 parts Water 60.5 parts Proxel CRL 0.2 parts A red aqueous pigment ink was obtained using the above ingredients in the same manner as in Example 1. Comparative Example 3 A red water-based pigment ink was prepared in the same manner as in Example 3, except that 2,2,4-trimethylpentanediol-1,3-monoisobutyrate in Example 3 was removed and water was added in the same amount. Obtained. (Effect of the invention) The water-based pigment inks obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were applied to a writing instrument having a polyester absorber and a polyacetal extrusion molded nib (0.6 mmφ).
Each sample was prepared by filling 1.65 g, and an ink discharge test and a pen tip drying resistance test were conducted. The results are shown in Table 1.

[Table] As described above, the water-based pigment ink of the present invention has excellent ink discharge properties and pen tip drying resistance.

Claims (1)

[Claims] 1. An aqueous pigment ink comprising at least a pigment, a dispersant, water, and trimethylpentanediol monoisobutyrate.