JPH0425314B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an aqueous pigment ink, and more particularly to an aqueous pigment ink having excellent dispersion stability and drying resistance.

Conventionally, water-based pigment inks have excellent water resistance and light resistance, and have been used for various purposes.

However, when used in low viscosity ink for writing instruments, etc., there was a problem that the dispersibility of the pigment was unstable and agglomerated easily, making writing impossible.

Therefore, as a dispersant for dispersing pigments,
Although various surfactants have been used, they have not yet been sufficient. In recent years, emulsions such as acrylic acid copolymers, amines and ammonium salts of acrylic acid copolymers have also been used, but since emulsions dry quickly, they may dry on the nib of a writing instrument, for example, or may not be exposed to solvents. There was a problem that the emulsion was sometimes destroyed.

Furthermore, particularly for ink for writing instruments, it is necessary to prevent drying at the pen tip as much as possible.

As a result of various studies as an agent for improving the dispersibility and drying resistance of the above-mentioned aqueous pigment ink, the present inventors found that the combination with a resin acid and an aminopropanol derivative improves the dispersibility and drying resistance of the water-based pigment ink. The present invention was completed based on this discovery.

That is, the gist of the present invention is an aqueous pigment ink characterized by containing a resin acid and an aminopropanol derivative represented by the following general formula.

general formula In the formula, R = H, CH ₃ , OH, CH ₂ OH n = an integer of 1 to 20.

Resin acids have been used in pigment inks for a long time, but this takes advantage of the film-forming ability of resin acids, and when used in writing instruments in large quantities, it becomes impossible to write if the nib dries. There was a problem that the writing quality became poor.

Therefore, in the present invention, by using a resin acid as a dispersant and an aminopropanol derivative which forms a salt with the resin acid, prevents the resin acid from forming a film, and has an effect on drying resistance, the above-mentioned This problem was solved.

The present invention will be explained in detail below.

Examples of resin acids include shellacs such as general shellac, dewaxing shellac, bleaching shellac, and bleaching shellac, humic acid, and rosin.

Aminopropanol derivatives represented by the general formula include 2-amino-2-methyl-1-propanol, 2-amino-2-ethyl-1-propanol, 2-amino-2-methyl-1.3-propanediol, 2-amino-2-methyl-1-propanol, and 2-amino-2-ethyl-1-propanol. Amino-2-ethyl-1,3-propanediol and their ethylene oxides 1-20
Examples include molar adducts.

All commonly available pigments can be used as pigments; examples include carbon black, phthalocyanine blue (C.
I.74160), Phthalocyanine Green (CI74260),
Hansa Yellow 3G (CI11670), Jisuazo Yellow GR
(CI21100), Permanent Red 4R (CI12335),
Briantocarmine 6B (CI15850), Quinacridone Red (CI46500), etc. can be used, and the amount used is preferably 5 to 20% by weight based on the total amount of the ink.

Incidentally, the type and proportion of the pigment used are selected as appropriate.

As the bath agent, not only water but also water-soluble organic agents such as glycol solvents, glycol ether solvents, glycol ether ester solvents, glycerin, and pyrrolidone can be used.

Others, 1,2-benzisothiazolin-3one,
Preservatives and fungicides such as pentachlorophenol and cresol, lubricants such as water-soluble silicone oil, and various surfactants can be appropriately selected and used.

The manufacturing method for water-based pigment ink consists of: 5-20% by weight of pigment, 70-40% by weight of water, 10-30% by weight of water-soluble organic solvent, 1-30% by weight of resin acid (in order to improve the wetting of the pigment, Surfactants may be used in an amount of 0.1 to 1% by weight), aminopropanol derivatives (0.1 to 1% by weight)
20% by weight and are mixed, ground, and dispersed using a pigment dispersion machine such as a ball mill, roll mill, sand mill, super mill, Dyno mill, or attritor.

The aqueous pigment ink thus obtained has unprecedented dispersion stability.

Hereinafter, the present invention will be described in detail based on Examples, where "parts" in the Examples indicate "parts by weight."

Example 1 Carbon black 10.0 parts Propylene glycol 5.0 parts Ethylene glycol 15.0 parts Shellac 2.0 parts 2-Amino-2-methyl-1-propanol
20.0 parts Labelin (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., anionic surfactant) 0.1 part Emulgen 931 (manufactured by Kao Atlas Co., Ltd., nonionic surfactant) 0.1 part Sodium pentachlorophenol (preservative)
0.1 part Water 47.7 parts Among the above components, water and 2-amino-2-methyl-
Add shellac to a solution of 1-propanol, stir at room temperature, and dissolve. Next, add Emulgen 931, ethylene glycol, and the remaining ingredients in order, premix with a stirrer for 2 hours, and then grind in a ball mill for 20 hours. , coarse particles are removed by filtration or the like.

The black water-based pigment ink obtained in this way was suction-filtered with 100 ml of Toyo Roshi No. 5c.
The entire amount passed through the filter paper within 30 seconds, and almost no residue was observed on the filter paper.

Further, this ink was processed in a centrifuge at 5000 rpm for 30 minutes, but no pigment sedimentation was observed.

Furthermore, even after filling a ballpoint pen with this ink, removing the cap, and leaving it in a constant temperature and humidity room at 20°C and 65% humidity for 10 days, the pen tip did not dry out and writing was still possible. .

Comparative Example 1 A water-based pigment ink was obtained in the same manner as in Example 1 except that shellac was removed and water was added. This ink has many coarse particles, and Toyo Roshi No.
It was not possible to filter with 5c.

Example 2 Copper phthalocyanine blue 15.0 parts Ethylene glycol 15.0 parts Propylene glycol 5.0 parts Decolorizing ceramic 1.0 parts 2-amino-2-methyl-1.3-propanediol 10.0 parts Proxel GBX (manufactured by ICI, preservative) 0.1 parts Water 53.9 parts Implementation In the same manner as in Example 1, the mixture was premixed after adjustment, mixed and ground in a sand mill for 10 hours, and coarse particles were removed to obtain a blue water-based pigment ink.

When this ink was suction filtered using 100 ml of Toyo Roshi No. 5c, the entire amount passed through the filter paper within 30 seconds, and no residue was observed on the filter paper.

Further, this ink was processed in a centrifuge at 5000 rpm for 30 minutes, but no pigment sedimentation was observed.

Furthermore, even after filling a ballpoint pen with this ink, removing the cap, and leaving it in a constant temperature and humidity room at 20°C and 65% humidity for 10 days, the pen tip did not dry out and writing was still possible. .

Comparative Example 2 In Example 2, 2-amino-2-methyl-
A water-based pigment ink was obtained in the same manner as in Example 2 except that 1.3-propanediol was removed and water was added.
The pen tip of this ink dried in one day under the same conditions as in Example 2.

Example 3 Copper phthalocyanine blue 10.0 parts Disazo yellow 5.0 parts Glycerin 2.0 parts Ethylene glycol 20.0 parts Humic acid 2.0 parts 10 moles of ethylene oxide added to 2-amino-2-methyl-1-propanol 10.0 parts Emulgen A-60 (Kao Soap ( Co., Ltd., nonionic surfactant) 0.1 part Water 50.9 parts A green aqueous pigment ink was obtained in the same manner as in Example 1.

When this ink was suction filtered using 100 ml of Toyo Roshi No. 5c, the entire amount passed through the filter paper within 30 seconds, and almost no residue was observed on the filter paper.

Further, this ink was processed in a centrifuge at 5000 rpm for 30 minutes, but no pigment sedimentation was observed.

Furthermore, even after filling a ballpoint pen with this ink, removing the cap, and leaving it in a constant temperature and humidity room at 20°C and 65% humidity for 10 days, the pen tip did not dry out and writing was still possible. .

As explained above, the aqueous pigment ink of the present invention using a resin acid and an aminopropanol derivative has excellent dispersibility and dispersion stability, and also has good drying resistance, and can be particularly used as a low viscosity ink. It can be suitably used for writing instruments using fiber, felt, and monofilament, capillary type writing instruments such as fountain pens, narrow rod type and ball point type writing instruments, and can also be used for recorders, printing, stamps, and jets. It can also be applied to printers, etc.

Claims (1)

[Scope of Claims] 1. An aqueous pigment ink comprising a resin acid and an aminopropanol derivative represented by the following general formula. general formula In the formula, R = H, CH ₃ , OH, CH ₂ , OH n = an integer of 1 to 20.