JPH01249869A - Water-based pigment ink - Google Patents

Abstract

PURPOSE:To obtain the subject ink, containing a pigment, dispersing agent, water and dimethyl sulfoxide, excellent in drying resistance of pen points and excellent in drying properties of scripts. CONSTITUTION:The objective ink containing at least preferably 2-20wt.% pigment (e.g., carbon black), preferably 1-20wt.% dispersing agent (e.g., gelatin, polyacrylate, PVA or alkylarylsulfonate), preferably 40-85wt.% water and preferably 2-40wt.% dimethyl sulfoxide.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an aqueous pigment ink that has excellent pen tip drying resistance and good handwriting drying properties.

[Conventional technology and its issues] Dye inks have traditionally been used as water-based inks for writing instruments, but due to insufficient light resistance and water resistance, the use of pigment inks has begun to emerge in recent years. Ta.

However, these water-based pigment inks have poor nib drying resistance, so ethylene glycol and glycerin are added as slow-drying agents, but the inclusion of these increases the viscosity of the ink. , there is a problem that penetrating the paper surface is poor, making it difficult for handwriting to dry.

[Means for Solving the Problems] The present invention has been made in view of the above problems, namely:
The gist thereof is a water-based pigment ink characterized by containing at least a pigment, a dispersant, water, and dimethyl sulfoxide.

Each component of the present invention will be explained in detail below.

The pigment is used as a coloring agent, and generally commercially available pigments can be used, but specifically, carbon black (C, 1,77265), phthalocyanine blue (
C,1,74160), phthalocyanine blue (C,1
, 74260), Hansa Yellow 3G (C, 1,116
70), Jisuazo! 0-GR(C.

1.21100), permanent L/7do 4R (C,
1°12335), brilliant carmine 6B (C,I
.

15850), Quinacridone Red (C,1,4'65
00), etc., or two or more thereof can be appropriately selected and used. The amount used is preferably 2 to 20% by weight based on the total amount of ink.

Polymer dispersants and surfactants used for pigment dispersion can be used as dispersants. Examples of polymer dispersants include proteins such as gelatin, albumin, and casein, natural rubbers such as gum arabic and gum tragacanth, and saponins. Glucosides, cellulose derivatives such as methylcellulose, carboxycellulose, and hydroxymethylcellulose, lignin sulfonates, natural polymers such as heplac, polyacrylates, salts of styrene-acrylic acid copolymers, vinylnaphthalene-acrylic acid copolymers anionic polymers such as salts of styrene-maleic acid copolymer, salts of vinylnaphthalene-iron maleate monopolymer, sodium salts of β-naphthalene sulfonic acid formalin condensates, phosphates, and polyvinyl alcohol. , polymeric dispersants such as nonionic polymers such as polyvinylpyrrolidone and polyethylene glycol; as surfactants, anions such as fatty acid salts, higher alcohol sulfate ester salts, liquid fatty oil sulfate ester salts, and alkylaryl sulfonates; There are nonionic surfactants such as surfactants, polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters. It can be selected and used as appropriate. The amount used is preferably 1 to 20% by weight based on the total amount of ink.

Water is used as the main solvent, and its weight is 40 to 85% by weight based on the total amount of ink.

Dimethyl sulfoxide is used to improve handwriting drying properties, and the amount used is preferably 2 to 40% by weight based on the total amount of ink.

If it is less than 2% by weight, the handwriting drying effect will be low,
If it is more than 40% by weight, handwriting tends to bleed.

In addition to the above ingredients, if necessary, water-soluble organic solvents such as glycol solvents, glycol ether solvents, glycol ether ester solvents, glycerin, pyrrolidone, sugars such as glycose, sorbitan, sorbitol, and known Wetting agents, antifreeze agents, preservatives, antifungal agents,
Additives such as rust preventive agents and complementary color dyes may be used as appropriate.

Next, various methods can be adopted as a method for manufacturing the aqueous pigment ink of the present invention. To give an example, first, the above-mentioned components are blended, and then mixed with a ball mill, a homomixer, a sand grinder, a speed line mill, It is obtained by mixing and grinding using a conventionally known dispersing machine such as a roll mill.

[Function] It is not clear why the aqueous pigment ink according to the present invention has excellent pen tip drying resistance and quick handwriting drying properties, but it is speculated as follows.

Dimethyl sulfoxide has the effect of preventing the pen tip from drying out, so there is no need to use large amounts of erythylene glycol, glycerin, etc. as slow-drying agents, and the ink has low viscosity, so it has low penetration into the paper surface. It is often assumed that handwriting dries faster.

[Example] The present invention will be described in detail based on the following examples. In the examples and comparative examples, the term "parts" simply means "parts by weight."

Disaster ■Futakami Carbon Black 10.0 parts (C,
1,77265) Styrene-maleic acid ammo 5.0 parts Nium salt (dispersant) Dimethyl sulfoxide 30.0 parts Water
55.0 parts The above components were blended, heated to 40 to 50°C, and stirred for 2 hours to obtain an aqueous black pigment ink.

Comparative Example 1 A water-based black pigment ink was obtained in the same manner as in Example 1, except that dimethyl sulfoxide was removed and glycerin was added in the same amount.

Example-2 Permanent Red 4R 15.0 parts (C, 1,12355) β-naphthalenesulfonic acid phor 8.0 parts Na salt of marine condensate (dispersant) Dimethyl sulfoxide 15.0 parts Ethylene glycol 5.0 parts water
57. Part o The above components were blended and the same procedure as in Example 1 was carried out to obtain an aqueous red pigment ink.

Comparative Example 2 A water-based red pigment ink was obtained in the same manner as in Example 2, except that dimethyl sulfoxide was removed and ethylene glycol was added in the same amount.

Example-3 Phthalocyanine blue 5.0 parts (C,
1,7,4160) Styrene-acrylic acid ammonium 2.0 parts Nium salt (dispersant) Dimethyl sulfoxide 5.0 parts Glycerin 18.0 parts Water
70.0 parts of each of the above components were blended and the same procedure as in Example 1 was carried out to obtain an aqueous blue pigment ink.

An aqueous blue pigment ink was obtained in the same manner as in Example 3, except that dimethyl sulfoxide, the main ingredient, was removed and glycerin was added in the same amount.

[Effect] The aqueous pigment inks obtained in Examples 1 to 3 and Comparative Examples 1 to 3 were applied to felt-tip pen 5520 (manufactured by Pentel ■) for 2. ．． 0g
It was filled and tested for dryness resistance of the pen tip and dryness of handwriting.

*1 Pen tip drying resistance: The cap was removed and the pen was left at a room temperature of 20° C. and humidity of 60%, and the time until it became impossible to write was measured.

*2 Handwriting drying property...JIS P
3201 was written on writing paper A, a homogeneous paper was placed over the handwriting, a 500 g weight was placed on it, and after leaving it for 1 minute, it was visually determined whether the handwriting had been transferred or not, and the time until the handwriting stopped being transferred was measured.

As described above, according to the present invention, an excellent aqueous pigment ink having excellent pen tip drying resistance and good handwriting drying property can be obtained.

Further, the aqueous pigment ink of the present invention can be used not only for writing instruments, but also for recorders, jet printers, stamps, etc.

Claims (1)

[Claims] An aqueous pigment ink characterized by containing at least a pigment, a dispersant, water, and dimethyl sulfoxide.