JPS629268B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a water-based black ink with good solubility, stability over time, and water resistance for use in writing instruments, stamps, printing, and recorders. Conventionally, CI Direct Black 19 has been widely used as a dye for writing instruments, stamps, printing, and recorders because of its good water resistance on paper. However, water-based inks tend to bleed and fade on paper, and there is a demand for better water-based inks. Also, even if the water resistance is good, it is not perfect compared to oil-based ballpoint pens. Furthermore, this type of dye has only two water-soluble sulfone groups in its structure, so it is expected to have water resistance. However, on the other hand, it has poor solubility and tends to precipitate, making it difficult to use in inks. The disadvantage was that the stability over time was a problem. As a result of extensive research into CI Direct Black 19 type dyes with the aims of (1) improving solubility in water-based ink solvents, and (2) improving water resistance and preventing bleeding and bleeding, the inventor found that sulfones were found in the dye structure. By introducing two or more groups and increasing the molecular weight while keeping the dye molecules linear, the above disadvantages were overcome and the desired aqueous black ink was obtained. That is, the present invention uses a tetrakisazo dye represented by the following general formula in place of CI Direct Black 19 as an aqueous ink. general formula (In the formula, R is a hydroxyl group or an amino group, Q is

[Formula] or

Represents [formula]. ) The above dyes used in the present invention are manufactured by CI Direct.
I have already explained that it is superior to Black 19, but even though there are four sulfone groups in one molecule, it has excellent water resistance and less bleeding, which is why the dye molecules with a linear structure are This is thought to be because it is easy to aggregate on cellulose (cellulose), and water resistance does not deteriorate even if the number of sulfone groups increases. All dyes shown in the above general formula have 4 in the dye molecule.
It has sulfone groups and its structure is linear. Similar to CI Direct Black 19, its synthesis is relatively easy. Next, the ink of the present invention will be explained. The present ink can be easily obtained by dissolving the dye mentioned above in an aqueous ink solvent according to a conventional method.
The amount of dye used is preferably 1 to 15% by weight based on the total amount of the water-based ink. Solvents used in the ink include alcohols such as ethanol, propanol, and butanol, glycols such as ethylene glycol, propylene glycol, butylene glycol, and glycol derivatives such as ethylene glycol monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether, Diethylene glycol monomethyl ether, monoethyl ether, monopropyl ether, monobutyl ether and their acetates, and amides include formamide, hexamethylphosphoramide, pyrrolidone, sugar alcohol, etc., and the amount used is 5% based on the total amount of water-based ink. ~40% by weight is preferred. Furthermore, alkanolamines, ureas, urethanes, etc. can be used as dye solubilizers, and preservatives and surfactants can also be added as necessary. This will be explained in detail below using examples. In the examples, parts simply refer to parts by weight. Example 1

[Table] The water-based black ink of the present invention was obtained by stirring the above components at room temperature. Comparative Example 1 In place of the dye in Example 1, a black ink was prepared by using the same amount of Kayarasu Black G Conc (CI Direct Black 19, manufactured by Nippon Kayaku Kogyo Co., Ltd.). Example 2

[Table] The water-based black ink of the present invention was obtained by stirring the above components at room temperature. Comparative Example 2 Kayalus Black G was used instead of the dye in Example 2.
A water-based black ink was prepared using the same amount of conc. 50ml of ink of Examples 1 and 2 and Comparative Examples 1 and 2
Place in a glass bottle with a cap at 0℃ for 48 hours:
The ink was dried through a rest cycle of 48 hours at 50° C. five times, and the presence or absence of dye precipitation in the ink was confirmed. The change in viscosity was also observed. The results are shown in Table-1.

[Table] Next, each ink was dripped onto JIS P3201 paper and spread with a rubber spatula. After 30 minutes, the colored test piece is immersed in still water for 10 minutes and then dried at room temperature. The density difference between the untested piece and the test piece was measured using a Hunter colorimeter. The results are shown in Table-2.

【table】

[Table] Also, fill a commercially available felt-tip pen with each ink, and
I wrote on P3201 paper (writing paper A) and visually checked the bleeding of the written lines. The results are shown in Table-3.

[Table] As described above, the water-based ink of the present invention has excellent solubility (stability over time), good water resistance, and little bleeding, so it can be used not only for writing instruments but also for stamps, printing, and recorders. It is also suitable for use.

Claims (1)

[Scope of Claims] 1. An aqueous black ink characterized by containing a tetrakisazo dye represented by the following general formula. general formula (In the formula, R represents a hydroxyl group or an amino group, and Q represents [formula] or [formula].)