JPH05271603A - Water-based pigment ink for ball-point pen - Google Patents

Abstract

PURPOSE:To obtain an ink which particularly gives a smoothness in writing when used in a ball-point pen having a stainless-steel tip by incorporating a small amount of a dialkylthiourea into a water-based ink. CONSTITUTION:A dialkylthiourea represented by the formula (wherein R is an alkyl represented by CnH2n+1, where (n) is 1-4) is incorporated into a water- based ink consisting essentially of a pigment, a dispersant, and water, in an amount of 0.05-0.1wt.% based on the whole ink, to obtain a water-based pigment ink for a ball-point pen having a stainless-steel tip. When used in such a ball- point pen, this ink is excellent in lubricating property and in the effect of reducing the friction between the ball holder and the ball in the tip, and hence does not cause drawn-line discontinuity. As a result, the distance over which smooth writing with the pen is possible can be increased significantly.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water-based pigment ink for ball-point pens, and more specifically, a water-based pigment for ball-point pens which can be applied to a ball-point pen using a stainless tip as a tip and can exhibit smooth writing. It is about ink.

[0002]

2. Description of the Related Art Conventional inks for water-based ballpoint pens are composed of water and a wetting agent, a surfactant and an antiseptic agent as an aqueous dye, and when a metal is used for the tip of the ballpoint pen,
A rust preventive agent is added. In addition, inks using pigments instead of dyes have been developed to improve water resistance and weather resistance.
When a copper alloy-based brass or nickel silver is used for the tip of the ball-point metal tip, there is no particular problem even if a commercially available water-based ball-pen ink containing a conventional pigment is used. However, in the case of a water-based ballpoint pen, the gap between the tip metal tip and the ball is large, so that the tip tip end wears and the ball easily falls off from the tip after long-term use. Therefore, stainless steel having wear resistance has come to be used. However, when a tip made of stainless steel (chrome steel containing 12 to 20% of chromium) is used as the tip metal tip of the ball-pen, the smoothness of writing is not sufficient as compared with the case of other metals, especially as a pigment. This tendency is remarkable in the case of black ink using carbon black.

Therefore, many inventions have been made in the past for improving the smoothness of inks for water-based ballpoint pens, and a few examples are as follows: metal soap, phosphoric acid type activator, silicone, Polyalkylene glycol, fatty acid ester, ethylene oxide addition type cationic activator,
Rotate oil, thiocarbamate and the like are known. However, there is no particular detailed description on the corresponding tip of the ball-point pen using the ink for water-based ball-point pen to which these are added, and it has not been researched and developed particularly considering the stainless tip. The present inventor applied these to stainless steel chips and tried them, but no satisfactory results were obtained.

[0004]

Therefore, as a result of intensive studies on the water-based pigment ink suitable for the ball-point pen of the stainless tip, the present inventors have found that the general formula is as follows.

[0005]

[Chemical 2]

(R is an alkyl group C _n H _{2n + 1} and n is 1 to 4)
The hydrophilic dialkylthiourea represented by
The present invention has been completed by finding that the smoothness is remarkably improved by adding 0.1% to 0.1%, and an object of the present invention is to provide a water-based pigment ink for a ball pen having a stainless tip.

[0007]

The present invention relates to an aqueous pigment ink comprising a pigment, a dispersant and an aqueous medium, to which a dialkylthiourea represented by the following general formula (I) is added. -It is based on a water-based pigment ink for rupen.

[0008]

[Chemical 3]

(R is an alkyl group C _n H _{2n + 1} and n is 1 to 4) That is, in the present invention, it is understood that the above dialkylthiourea acts as a lubricant.

Japanese Patent Publication No. 11-3507 is an example in which a dialkyl thiourea is added to a water-based ink for ballpoint pens. However, according to the publication, a dye is an essential component as a colorant, nothing is described about a pigment, and the effect is to improve the corrosion resistance of a cemented carbide ball. However, the chip made of polyacetal resin is used instead of metal. Of course, there is no description about lubricity problems or stainless chips. Moreover, the addition amount of dialkylthiourea shown in the publication is 0.1% to 10%, and the addition amount of dialkylthiourea of 0.05 to 0.1% is sufficient in the present invention. The effect and the addition amount range are completely different. In the case of the present invention, however, the effect tends to decrease if 0.2% or more is added. The scientific reason why the present invention is sufficient at 0.05 to 0.1% is not clear, but it is probably due to the fact that about a monolayer is adsorbed on the portion of the stainless chip holding the ball. It is speculated that this is being demonstrated.

Next, the present invention will be described in detail. As the colorant used in the present invention, conventionally known inorganic pigments and organic pigments can be used. The form can be used without problems such as powder and wet cake. The amount of these pigments used is preferably 3 to 20% with respect to the total amount of the ink.

Next, as a water-soluble polymer which is a dispersant, an ammonium salt of a styrene-acrylic acid copolymer,
An ammonium salt of a styrene-maleic anhydride copolymer or polyoxyethylene nonylphenyl ether as a surfactant can be used. The amount used is preferably 2 to 12% with respect to the total amount of ink.

The water medium which can be used in the present invention is mainly composed of water, but if necessary, a hardly volatile water-soluble organic solvent such as ethylene glycol, diethylene glycol, propylene glycol or glycerin is used. It is possible to use it, and the amount used is preferably 5 to 30% based on the total amount of ink.

The lubricant which is the essence of the present invention is a dialkylthiourea represented by the following general formula (I) which is a water-soluble substance.

[0015]

[Chemical 4]

(R is an alkyl group C _n H _{2n + 1} and n is 1 to 4) Specific examples include dimethylthiourea, diethylthiourea, dipropylthiourea and dibutylthiourea. The amount used can be 0.05 to 0.10% with respect to the total amount of ink.

Other hygroscopic substances such as urea and thiourea, preservatives, rust preventives, wetting agents and the like can be optionally used as required.

The water-based pigment ink for ball pens of the present invention comprises
It consists of the above-mentioned components, and its manufacturing method is a known method,
For example, it can be easily obtained by mixing and milling with a disperser such as a ball mill, a sand mill and a roll mill.

The water-based pigment ink for ball-point pens of the present invention obtained as described above has sufficient stability both in the ink alone and in the water-based ball-point pen shaft, and does not change the quality of the ink in the aging test. Smooth writing is possible.

(Function) The water-based pigment ink for ball pens according to the present invention reduces the friction between the ball holder and the ball of the stainless steel and reduces the wear of the ball holder of the stainless steel tip. Although it is not certain that it has a preventive effect, it is presumed as follows.

The dialkylthiourea has a two-layer structure in the ball holder of the stainless steel chip, the first group is the alkyl group on the outside, and the C = S groups are arranged on the stainless steel surface.
It is considered that the second layer is arranged with the alkyl group on the inside and the C = S group on the outside to improve the lubricity between the ball holder part and the ball of the stainless chip. Hereinafter, the present invention will be described in more detail with reference to Examples. In Examples, "part" means "part by weight".

[0022]

【Example】

Example 1 Carbon black 8 parts Discoto N-14 (manufactured by Dai-ichi Kogyo Seiyaku Co., ammonium salt of styrene-maleic acid copolymer) 8.9 parts Ethylene glycol 20 parts Glycerin 5 parts Urea 5 parts Water 52.81 parts Biocide 880 (manufactured by Taisho Co., Ltd., nitrogen-sulfur preservative) 0.1 part Benzotriazole 0.1 part Dimethylthiourea 0.09 part The above ingredients were charged in a ball mill and mixed and ground for 24 hours. Then, the coarse pigment particles were centrifugally separated and gradually removed to obtain an aqueous pigment ink black for ballpoint pen.

Example 2 Heliogen Bull-L6875F (BASF) 7 parts Johncryl 61-j (manufactured by Johnson Polymer Co., ammonium salt of styrene-acryl copolymer) 9.8 parts ethylene glycol 20 parts diethylene glycol 10 Part Perex OTP (Kao Soap, sodium dialkylsulfosuccinate) 0.3 part Water 52.75 parts Biocide 880 (manufactured by Taisho Co., Ltd., nitrogen-sulfur preservative) Benzotriazole 0.1 part Diethylthiourea 0.05 Parts The above components were charged in a ball mill, mixed and ground for 24 hours, and coarse pigment particles were removed by a centrifuge to obtain an aqueous pigment ink blue for ball pens.

Example 3 Permanent Red FGR (Hoechst) 8 parts Neugen EA140 1.5 parts Neugen EA170 1.5 parts Ethylene glycol 20 parts Diethylene glycol 5 parts Urea 5 parts Water 58.72 parts Biocide 880 ( Taisho Co., Ltd., nitrogen-sulfur preservative) 0.1 part Benzotriazole 0.1 part Dibutylthiourea 0.08 part The above components are charged in a ball mill and mixed and ground for 24 hours, and coarse pigment particles are centrifuged. It was removed by a separator to obtain a water-based pigment ink red for ball-point pen.

Comparative Examples Inks were prepared in the same manner as in Examples 1, 2 and 3 except that the dialkylthiourea was removed, to obtain Comparative Examples 1, 2, and 3. About 6 kinds of inks adjusted as above, diameter 0.5m
A water-based ballpoint pen was assembled using a stainless steel tip using a m super hard ball, and its writability and writing taste were examined. Regarding writability, load 100 g, speed 4.0 m /
Machine writing was done in minutes to check the writing distance. In addition, a ruler was applied by hand to a high-quality paper, a line was drawn at a high speed, and the presence or absence of line skipping was examined. I checked handwriting.

[0026]

[Table 1]

Note 1) Using a commercially available rotation type continuous writability measuring device (spiral type), a writing speed of 7 cm / sec and a load of 100
Continuous writing was performed at g and an angle of 60 °, and the writing distance until the occurrence of blurring was measured.

[0028]

INDUSTRIAL APPLICABILITY As described above, when the ink of the present invention is used in a water-based ballpoint pen, it is excellent in the effect of reducing the friction between the ball holder portion of the stainless steel tip and the ball, the lubricity, and the line skipping. As a result, the writing distance that allows smooth writing can be greatly extended.

Claims (1)

[Claims] 1. A water-based ink comprising a pigment, a dispersant and water as a base material, and a dialkylthiourea represented by the following general formula (I) in an amount of 0.05 to less than 0.1% by weight based on the total amount of the ink. A water-based pigment ink for ball-point pens with a stainless steel tip characterized by being blended (R is an alkyl group C _n H _{2n + 1} and n is 1 to 4)