JPH0559316A - Water-base ink composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition capable of preventing the break of written mark, clogging of pen, etc., because of excellent drying resistance at the ink-ejection part such as pen tip by compounding imidazole or an imidazole ring-containing compound as a drying-prevention agent to a colorant and water. CONSTITUTION:The objective composition is produced by compounding (A) a colorant, (B) water and (C) preferably 0.01-20wt.% (based on the total ink composition) of imidazole and/or a compound having imidazolyl ring. The imidazolyl ring-containing compound of the component C is e.g. 2,4- diethylimidazole and 2-phenylimidazole. A conventional dye or pigment can be used as the component A.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based ink used for writing instruments, recorders, ink jet printing and the like, and more particularly to a water-based ink composition having excellent drying resistance at an ink ejection portion such as a pen tip. Is.

[0002]

2. Description of the Related Art Conventionally, inks used for writing instruments, recorders, ink jet printing and the like are composed of at least a coloring material, a water-soluble organic solvent and water. In general, ink that uses water as the main solvent causes phenomena such as thickening of ink and deposition of coloring material due to evaporation of water in the ink, resulting in a decrease in ink ejection from the pen tip (so-called blur).
Also, problems such as a decrease in ink ejection (so-called clogging) in the ink ejection holes are likely to occur.

Therefore, in order to prevent the occurrence of the above-mentioned problems, conventionally, a glycol solvent such as ethylene glycol, diethylene glycol, triethylene glycol or thiodiglycol, or a hygroscopic high-boiling solvent such as glycerin is water-soluble. It was used as an organic solvent. That is, the above-mentioned conventional ink has a design concept of compensating for the evaporated water due to the hygroscopicity of the water-soluble organic solvent in order to obtain good drying resistance.

[0004]

However, the water-soluble organic solvent is generally a compound having a high viscosity. On the other hand, ink used for writing instruments, recorders, ink jet printing, etc. is discharged through a capillary tube such as a pen tip or an orifice. Therefore, there is a limit to the amount of the water-soluble organic solvent that can be used in the ink, and the amount of use within that limit cannot sufficiently compensate for the evaporated water.

[0005]

DISCLOSURE OF THE INVENTION The present invention is intended to obtain an ink composition having excellent drying resistance of an ink ejection portion such as a pen tip, and comprises a colorant, water, and imidazole. And / or an aqueous ink composition containing at least a compound having an imidazolyl ring.

The details will be described below. As the coloring material, conventionally known dyes and pigments can be used alone or in combination. Examples of the dye include C.I. I. Acid Red 52, C.I. I. Acid Blue 1, C.I. I. Acid black 2, acid dyes such as 123, C.I. I. Direct Black 19, C.I.
I. Direct dyes such as Direct Blue 86, C.I. I. Basic Blue 7, C.I. I. Basic dyes such as Basic Red 1 are mentioned. As the pigment, an azo pigment,
Condensed polyazo pigments, phthalocyanine pigments, quinacridone pigments, indigo pigments, thioindigo pigments, nitroso pigments, basic dye pigments, acid dye pigments, vat dye pigments, mordant dye pigments and natural pigment pigments Examples thereof include organic pigments such as pigments and inorganic pigments such as iron black, carbon black, ocher, barium yellow, navy blue, cadmium red, titanium oxide, and red iron oxide.

The compound having an imidazole and / or imidazolyl ring is used as an anti-drying agent such as a pen tip. Specific examples of the compound having an imidazolyl ring are shown below, and 2,4-diethylimidazole, 2
-Phenylimidazole, 1-benzyl-2-methylimidazole, 1- (2-cyanoethyl) -2-phenylimidazole, 4,5-hydroxymethyl) -2-phenylimidazole, 5-hydroxymethyl-4-methyl-2- Examples include phenylimidazole. The amount of the above substances used is 0.01 to 2 with respect to the total amount of the ink composition.
0.0 wt% is preferred.

Water is used as the main solvent.

In addition to the above essential components, glycol solvents such as ethylene glycol, diethylene glycol and triethylene glycol, known solvents such as glycerin, preservatives and antifungal agents may be appropriately selected and used as necessary. Good.

To obtain the water-based ink composition of the present invention, a conventionally known method can be used. When a dye is used as the coloring material, each component is stirred and mixed using a stirrer,
When a pigment is used, each component is dispersed and mixed using a disperser.

[0011]

The compound having an imidazole and / or an imidazolyl ring used in the water-based ink composition according to the present invention has an effect of suppressing evaporation of a solvent containing water. It is presumed that the evaporation of the solvent is suppressed. Further, since the present ink composition does not use a large amount of high boiling water-soluble organic solvent, the ink viscosity does not increase.

[0012]

EXAMPLES The present invention will be described in more detail below with reference to examples. In the examples and the comparative examples, simply "part" means "part by weight".

Example 1 CI Acid Orange 56 10.0 parts Propylene glycol 10.0 parts Ethylene glycol 10.0 parts Proxel GXL (manufactured by ICI Japan Co., a fungicide) 0.5 parts 2,4 -Diethylimidazole 15.0 parts Water 54.0 parts

Example 2 CI Acid Violet 17 5.0 parts Ethylene glycol 20.0 parts Neugen-P (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., surfactant) 0.2 parts 2-phenylimidazole 05 parts water 74.75 parts

Example 3 CI Acid Violet 49 6.0 parts CI Acid Blue 9 7.0 parts ethylene glycol 15.0 parts thiodiglycol 10.0 parts 1-benzyl-2-methylimidazole 3 0.0 parts Water 59.0 parts

Example 4 Carbon black 10.0 parts Glycerin 10.0 parts Ethylene glycol 10.0 parts Styrene-ammonium acrylate (dispersant) 10.0 parts Silicon KM-73 (Shin-Etsu Silicone Co., Ltd., silicone oil) ) 0.2 part 5-hydroxymethyl-4-methyl-2-phenylimidazole 0.1 part water 59.7 parts

Example 5 Carbon black 8.0 parts Glycerin 10.0 parts Styrene-sodium acrylate 10.0 parts Silicon KM-73 0.2 parts 4,5-Hydroxymethyl-2-phenylimidazole 5.0 parts Water 66.8 copies

Comparative Example 1 CI Acid Red 87 6.0 parts CI Acid Yellow 7.0 parts ethylene glycol 10.0 parts thiodiglycol 10.0 parts water 67.0 parts

Comparative Example 2 Carbon black 10.0 parts Glycerin 10.0 parts Ethylene glycol 10.0 parts Styrene-ammonium acrylate 10.0 parts Silicon KM-73 0.2 parts Water 59.8 parts

As described above, in Examples 1 to 3 and Comparative Example 1, each component was stirred for 1 hour while being heated to 30 ° C. to obtain an ink composition. In Examples 4 to 5 and Comparative Example 2, an ink composition was obtained by dispersing for 1 hour with a disperser.

[0021]

[Effect] The ink compositions obtained in Examples 1 to 5 and Comparative Examples 1 and 2 were tested. The results are shown in Table 1.

[0022]

[Table 1]

Pen tip drying resistance test: (Method) 2.0 g of each ink composition was filled in a writing instrument similar to that of a commercially available ball-point pen using a water-based ink (Super Ball BH14, manufactured by Pentel Co., Ltd.), and the temperature was 20 ° C. Under the condition of humidity 65%,
After leaving for a certain period of time with the cap removed from the writing instrument, handwriting was performed on a fine-quality paper and the handwriting was observed. (Evaluation) ○: Writing is possible △: There is some blurring ×: Writing is not possible

As described in detail above, the ink composition of the present invention is excellent in the drying resistance of the pen tip, and has the excellent characteristics that the conventional ink-based ink does not cause scratches. ..

Claims (1)

[Claims] 1. An aqueous ink composition comprising at least a colorant, water, and a compound having an imidazole and / or an imidazolyl ring.