JPS63243181A - Ink for ball point pen - Google Patents

Abstract

PURPOSE:To provide an ink for ball point pen, containing a specific carboxymethlcellulose, adjusted to specific ink viscosity and pH, having characteristic features of both oil-based ink and water-based ink and causing little viscosity variation with time. CONSTITUTION:The objective ink can be produced by compounding (A) a colorant, (B) water, (C) a water-soluble organic solvent and (D) a viscosity modifier consisting of a carboxymethlcellulose having an etherification degree of >=1.4 and adjusting the ink viscosity to 50-2,000cps (25 deg.C) and ink pH to 8.5-11.5. The amount of the component C is preferably <=1/2wt.% based on water in the ink.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an ink for ballpoint pens, and more specifically, it combines the features of oil-based inks and water-based inks for ballpoint pens,
Furthermore, the present invention relates to a ballpoint pen ink that exhibits little change in viscosity over time.

(Prior Art) The inventors of the present application have an advantage of oil-based ballpoint pen ink. It is possible to check the amount of ink remaining.

The advantage of water-based ballpoint pen ink is that it does not bleed and can be written smoothly. An ink for ballpoint pens that provides highly saturated handwriting without line breakage or smearing, and is made of at least one coloring material, water, a water-soluble organic solvent, and a viscosity modifier, and has an ink viscosity of 50 to 2000 cp.
We have previously proposed a ballpoint pen ink characterized by a temperature range of 25°C.

(Problems to be Solved by the Invention) The present invention relates to an improvement of the ballpoint pen ink according to the above-mentioned proposal, and relates to a ballpoint pen ink using carboxymethyl cellulose as a viscosity modifier.

In other words, ballpoint pen inks that use carboxymethylcellulose, a viscosity modifier that provides a particularly smooth writing feel, tend to lose their viscosity over time, leading to an imbalance in writing and handwriting functions. It contained potential.

(Means for Solving the Problems) Therefore, the inventors of the present invention have conducted various studies in order to prevent the viscosity from decreasing, and have finally completed the present invention. A ballpoint pen ink comprising at least a viscosity modifier and having an ink viscosity in the range of 50 to 2000 cps (25°C), wherein the viscosity modifier is carboxymethyl cellulose with an etherification degree of 1.4 or more, and the ink pH is a5 to The gist of the present invention is an ink for a ballpoint pen characterized by having a molecular weight in the range of 11.5.

Two aspects of the present invention will be described in detail below.

As the coloring material, conventionally known coloring materials can be used without particular limitation, and specifically, acid dyes, basic dyes,
In addition to water-soluble dyes such as direct dyes, water-insoluble colorants such as organic pigments, inorganic pigments, and metal powders can also be used, and they can be used alone or in combination as appropriate.

Examples of water-soluble organic solvents include glycols such as ethylene glycol, diethylene glycol, triethylene glycol, fluoropylene glycol, polyethylene glycol, 1,3-butylene glycol, thiodiethylene glycol, and glycerin;
-chill, diethylene glycol monomethyl ether/l/
, 2-hyrrolidone, N-methyl-2-pyrrolidone, triethanolamine, etc. are used, and the amount used is 1/2% by weight of water in the ballpoint pen ink, and the degree of etherification is 1.4 or more. In addition, the pH of the ink
It is necessary to use in the range of a5 to 11.5.

If the degree of etherification is less than 1.4, the ink pH will be a
Even in the range of 5 to 11.5, the viscosity decreases a lot, and
This is because when the pH is lower than a5, the viscosity decreases significantly even if the degree of etherification is 1.4 or higher.

Further, if the ink pH is 11.5 or higher, the thickening effect of carboxymethyl cellulose is insufficient, which is not preferable.

The ink pH adjuster may be any water-soluble alkaline substance, and alkali metal aqueous dispersions and ethanolamines are particularly preferably used. In addition to the above essential ingredients, known surfactants, preservatives, fungicides, rust preventives,
A lubricant or the like may be added as appropriate. In order to obtain this ballpoint pen ink, conventionally known methods are used, but if the coloring material is water-soluble, it can be easily obtained by stirring and mixing, and if the coloring material is water-insoluble, it can be obtained using a dispersion machine. Obtained by dispersing and mixing.

Furthermore, filtering the ink obtained by the above-mentioned two-step method is also a possible step in the method for producing ink for two-ballpoint pens.

(Function) The reason why the ink for ballpoint pens according to the present invention shows little change in viscosity over time is surmised as follows.

In the first place, carboxymethyl cellulose is a cellulose needle made by reacting alkali cellulose with chloroacetate, and is produced by substituting a carboxymethyl position on the hydroxyl group of alkali cellulose.The degree of substitution is referred to as the degree of etherification. However, carboxymethylcellulose with a low degree of etherification is thought to have its molecular chains cleaved by hydrolysis, resulting in a decrease in viscosity.

Furthermore, it is thought that the action of carboxymethyl cellulose degrading enzymes present in the air etc. also causes molecular chains to be cut and the viscosity to decrease.

Therefore, the change in viscosity over time was reduced by using carboxymethylcellulose with a high degree of etherification, which is less likely to undergo hydrolysis, and by adjusting the pH of the ink to an alkaline side, where the degrading enzyme is less likely to be active.

(Example) The present invention will be described in more detail based on the following two examples. In the examples and comparative examples, "parts" indicate "parts by weight."

Example 1 Water Blue 9 (acidic dye.

(manufactured by Orient Chemical Industry ■) 8 parts CMC-Daicel ◆ 2000 (carboxine methyl cellulose, degree of etherification 1.41 manufactured by Daicel Chemical Industry ■) 0.8 parts ethylene glycol 20 parts water
71.2 parts Mix the above ingredients, stir for 30 minutes, and add 25% of the sodium hydroxide.
After adding the aqueous solution and adjusting the pH to 97,
The mixture was stirred for a minute and then filtered through a 1.0 μm filter to obtain a blue ballpoint pen ink with a viscosity of 550 cps and a pH of 10.7.

Comparative Example 1 The same procedure as in Example 1 was carried out except that 0M0-Daicel φ2000 in Example 1 was replaced with 0M0-Taicelna 1190 (carboxymethyl cellulose, degree of etherification 1.2, manufactured by Daicel Chemical Industries, Ltd.).

A blue ballpoint pen ink with a viscosity of 280 cps and a pH of 10.7 was obtained.

Comparative Example 2 In Example 1, p using a 25% aqueous solution of sodium hydroxide
The procedure was the same as in Example 1 except that the H adjustment was omitted, and the viscosity was 3.
Obtained 50 cps, pH 7.4 blue ballpoint pen ink.

Example 2 MAloo (carbon black.

(manufactured by Mitsubishi Chemical Corporation) 10 parts SMARes
in 1440 (dispersant.

ABC! O Chemical Co., Ltd.) 5 parts glycerin 15 parts CMO-TSB46 (
Carboxymethylcellulose, degree of etherification 1.6゜manufactured by Daicel Chemical Industries, Ltd.) α7 part water
693
After mixing the above components and dispersing them in a ball mill for 24 hours, triethanolamine was added to adjust the pH to 90.
After that, it was filtered with a 1 μm filter, and the viscosity was 1260 cps.

A black ballpoint pen ink having a pH of 9.0 was obtained.

Comparative Example 5 Expressed in the same manner as in Example 2 except that the pH adjustment using triethanolamine was omitted, and the viscosity was 1260 cp.
A black ballpoint pen ink having a pH of 7.2 was obtained.

(Effect of the invention) Above, Examples 1 and 2. The bows obtained in Comparative Examples 1 to 3 were filled with pen ink in a sealed bottle and left in an atmosphere at 50°C to examine changes in viscosity. The results are shown in the table.

As described above in detail, the ballpoint pen ink according to the second invention has little change in viscosity over time.

It has always been a ballpoint pen ink that combines the features of water-based ballpoint pen ink and oil-based ballpoint pen ink.

Patent engineer Bendel Co., Ltd.

Claims (1)

[Claims] It consists of at least a coloring material, water, a water-soluble organic solvent, and a viscosity modifier, and the ink viscosity is adjusted to 50 to 2000 cps (25°C).
An ink for a ballpoint pen, characterized in that the viscosity modifier is carboxymethyl cellulose with a degree of etherification of 1.4 or more, and the ink pH is in the range of 8.5 to 11.5.