JPS6248776A - Aqueous ink composition - Google Patents

Abstract

PURPOSE:The titled ink composition, obtained by incorporating a water-soluble organic solvent with a water-soluble dye, etc., and a specific amount of glycyrrhizic acid or a salt thereof, having improved lubricity and capable of preventing abrasion of balls in the tip and giving good sense of writing with nondrying property. CONSTITUTION:An aqueous ink composition obtained by incorporating (A) a water-soluble organic solvent, e.g. ethylene glycol, with (B) a water-soluble or water-dispersible pigment and (C) 0.1-10.0wt% preferably 0.5-5wt% glycyrrhizic acid or a salt thereof. Preferably, the compounding ratio of the component (A) is 5-50wt% based on the total composition.

Description

[Detailed description of the invention] Industrial applications The present invention relates to a water-based ink composition.

More specifically, the present invention relates to a water-based ink composition for ballpoint pens and felt-tip pens that has excellent lubricity, is effective in preventing wear of the tip ball and ball holder, is non-dry, and has a good writing feel. 6. Conventional technology Conventionally, water-based inks for ballpoint pens and felt-tip pens have been made by adding a water-soluble polyhydric alcohol such as a glycol solvent or a glycol ether ester solvent to an aqueous solution containing a water-soluble dye. It is being However, such water-based inks have poor lubricity, so when used in a water-based ballpoint pen, for example, the rotation of the ball during writing causes wear on the ball and ball holder, causing the gap between them to become large, causing the ball to wobble or cause the ball to become loose. This causes problems such as irregular rotation of the ink, resulting in poor initial writing quality and uneven ink flow.

For this reason, attempts have been made to add water-soluble cutting oil or water-soluble resin to the water-based ink. However, the former improves abrasion resistance and writing quality, but has the problem that drawn lines tend to bleed, while the latter improves abrasion resistance but increases the viscosity of the ink, making the ink flow smoother. Moreover, it also causes blurring and ink running out, and has the drawback that lubricity cannot be improved if the amount added does not increase the viscosity.

Furthermore, attempts have been made to add unsaturated fatty acids to water-based inks. However, in this method, although the abrasion resistance is improved, the unsaturated fatty acid has a low solubility in water and separates in the ink over time, so there is a drawback that the lubricating effect cannot be maintained for a long period of time.

Problems to be Solved by the Invention The purpose of the present invention is to improve the drawbacks of the conventional water-based ink for ballpoint pens and felt-tip pens, to have excellent lubricity, and to prevent wear of the tip ball and ball holder. To provide a water-based ink composition for ballpoint pens and felt-tip pens, which is effective, has excellent long-term stability and prevention of bleeding, is non-dry, and has good writing taste.

Means for Solving the Problems As a result of extensive research to achieve the above object, the present inventors found that an ink composition containing a water-soluble organic solvent and a water-soluble dye or a water-dispersible pigment has the following properties. It was discovered that the objective could be achieved by blending a fixed amount of glycyrrhizic acid or its salt, and based on this knowledge, the present invention was completed.

That is, the present invention provides an ink composition comprising a water-soluble organic solvent and a water-soluble dye or a water-dispersible pigment,
Furthermore, based on the weight of the entire ink composition, at least one selected from glycyrrhizinic acid and its salts, from 0.1 to
The present invention provides an aqueous ink composition characterized in that it contains 10.0% by weight.

Examples of the water-soluble organic solvent used in the water-based ink composition of the present invention include water-soluble polyhydric alcohols such as ethylene glycol and diethylene glycol, cellosolve solvents such as methyl cellosolve, and glycols such as ethylene glycol monoethyl ether acetate. Preferred examples include ether ester solvents. These water-soluble organic solvents may be used alone or in combination of two or more, and the preferred content thereof is in the range of 5 to 50% by weight based on the total composition.

Further, the water-soluble dye used in the aqueous ink composition of the present invention can be arbitrarily selected from among acid dyes, direct dyes, basic dyes, etc. used in ordinary aqueous ink compositions.

Further, in the aqueous ink composition of the present invention, a water-dispersible pigment dispersed using a water-soluble resin or the like may be used alone or in combination with the dye.

Glycyrrhizic acid used in the aqueous ink composition of the present invention is a compound represented by the structural formula, and is water-soluble, but easily soluble salts such as sodium salt, potassium salt, and ammonium salt may also be used. can. These glycyrrhizic acids and their salts may be used alone or in combination of two or more, and by containing these compounds in the aqueous ink composition, the compounds will be adsorbed to the ball and holder. By forming a continuous layer between the ball and the holder, it is believed that the coefficient of friction between the ball and the holder is reduced and the lubrication effect is enhanced. Furthermore, since glycyrrhizic acid and its salts have excellent moisturizing properties, they also have the effect of delaying the drying of the pen tip. In the present invention, the content of these compounds is
The amount is selected in the range of 0.1 to 10% by weight, preferably 0.5 to 5% by weight based on the total ink composition. This amount is 0.1
If it is less than 10% by weight, the effect of the present invention cannot be obtained, while if it exceeds 10% by weight, bleeding tends to occur when writing.

The water-based ink composition of the present invention can be prepared by dissolving the above-mentioned water-soluble organic solvent and water-soluble dye in water, or by adding a water-dispersible pigment dispersed using a water-soluble organic solvent and a water-soluble resin to water. , preservatives, rust inhibitors, pH if necessary for this
It is obtained by containing a regulator, an anionic or nonionic surfactant, a water-soluble resin, etc., and further containing a predetermined amount of glycyrrhizic acid or a salt thereof.

Effects of the Invention The aqueous ink composition of the present invention contains glycyrrhizic acid or its salt, and has excellent lubricity. Whether it is made of metal such as stainless steel or synthetic resin, it prevents wear on the ball and the catch of the holder that the ball comes into contact with, provides a smooth writing feel, and can be left without a cap. It also has characteristics such as the nib of the pen does not dry easily, and is also excellent in long-term stability and smear prevention, making it suitable for use in ballpoint pens and felt-tip pens.

Example Next, the present invention will be explained in more detail with reference to Examples.

In addition, the performance of the ink composition is based on free-cutting nickel silver material and φ0.5
A tip using a zz carbide ball was assembled into a pen, and evaluated as follows.

(1) Fi machine writing performance Under the conditions of a load of 100 g and a speed of 411/min] After writing with 000z, the sinking of the ball and the writing feel were examined.

(2) Dry-up property The pen was left in a constant temperature and humidity chamber at a temperature of 25°C and a humidity of 60%, and the degree of fading of drawn lines was examined every 10 days.

Example 1 Water 67
．． 8t% ethylene glycol 10.
Ou+t% propylene glycol 15.
Ou+t% monoammonium glycyrrhizinate 2.0
7% El7-el (preservative) 0.1% Score Roll #900 (7ionic surfactant) 0.1LLI
L% Edible Red No. 102 (C, 1, No. 16255)
5. Ou+t% The above formulation was stirred at 50°C±10°C for 1 hour, cooled, and then filtered to prepare an aqueous red ink composition of the present invention (referred to as Ink 8-1).

For comparison, the water content was increased to 69.8+u without using monoammonium glycyrrhizinate in the above composition.
An aqueous red ink composition was prepared in the same manner (ink A-2) except that the composition was changed to t%.

The performance of these ink compositions was determined and the results are shown in the attached table.

Example 2 Water 62
．． 8t% ethylene glycol 20.
Quit% no ethylene glycol 10,
0 Iut% sodium glycyrrhizinate 2.
0+lIt%phenol 0
0lust% Sufu 70-le 9900 0
．． 1□t% Edible Red No. 106 (C, 1, No. 4510
0) 1.5u+t% Food Blue No. 1 (C, I,
No. 42090) 3.5+ut% The above formulation was treated in the same manner as in Example 1 to prepare an aqueous blue ink composition of the present invention (referred to as Ink B-1).

For comparison, an aqueous blue ink composition was prepared in the same manner (referred to as ink B-2) except that sodium glycyrrhizate/sodium acid was not used and the water content was 64.8 u+t%.

The performance of these ink compositions was determined and the results are shown in the attached table.

Example 3 Water 55
．． 7+ut% ethylene glycol 20
．． Quit% diethylene glycol 10
．． 0+nt% potassium glycyrrhizinate 4
．． 0+llt%7 e/-le 0
．． 1u+j% score roll #900 0
．． 2ult%C,I, Direct Black 1
9 (C01, No, 35255)
10. Owt% The above formulation was treated in the same manner as in Example 1 to prepare an aqueous black ink composition of the present invention (referred to as Ink C-1).

For comparison, a water-based black ink composition was prepared in the same manner except that potassium glycyrrhizinate was not used and the water content was 59.7 u+t% (referred to as ink C-2).

The performance of these ink compositions was determined and the results are shown in the attached table.

Example 4 Water 64
,8u+t% ethylene glycol 25
,0iut% glycyrrhizic acid 1
, 0wt% sodium glycyrrhizinate 1.
Ou+t%phenol O,h
L% score roll #900 0.1...
t% Nigrosine R-500 (Orient Chemical Industry Wave) 8. Owt%
The above formulation was treated in the same manner as in Example 1 to prepare a water-based black ink composition of the present invention (referred to as Ink D-1).

For comparison, an aqueous black ink composition was prepared in the same manner except that glycyrrhizic acid and sodium glycyrrhizinate were not used and the water content was 66.8 vt% (referred to as ink D-2).

The performance of these ink compositions was determined and the results are shown in the attached table.

As can be seen from this table, the water-based ink composition of the present invention has excellent machine writability and good dry-up properties.

Further, the ink composition of the present invention does not cause bleeding of drawn lines,
It had good solubility and also excellent long-term stability over time.

Claims (1)

[Claims] 1. In an ink composition comprising a water-soluble organic solvent and a water-soluble dye or a water-dispersible pigment, based on the weight of the entire ink composition, at least one selected from glycyrrhizic acid and its salts is added. An aqueous ink composition characterized by containing 1 to 10.0% by weight.