JPS6072968A - Water-based pigment ink - Google Patents

Abstract

PURPOSE:To provide a water-based pigment ink which is excellent in dispersibility and dispersion stability and has good drying resistance and low viscosity, by incorporating sorbitan or isosorbite in a water-based pigment ink. CONSTITUTION:Sorbitan and/or isosorbite are/is incorporated in a water-based pigment ink such as an ink contg. a pigment such as carbon black or phthalocyanine blue as well as dispersant, water, water-soluble org. solvent, etc. The resulting ink is excellent in dispersibility and dispersion stability, has good drying resistance and can be used as a low-viscosity ink which is suitable for use in a capillary tube type of writing utensils such as a fountain pen or writing utensils using fiber, felt or monofilament, or slender lever type and ball point pen type of writing utensils. The ink can also be used for recorder, printing, stamp, jet printer, etc.

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 been used for a variety of purposes, with poor water resistance and light resistance.

However, when used at low viscosity, such as ink for writing instruments, the dispersibility of the pigment is unstable and it tends to aggregate.

There was a problem that I could no longer write Eki.

Therefore, it is used as a dispersant to disperse 9M family.

Various types of surfactants have been used, but they are still not sufficient. In recent years, emulsions such as acrylic acid copolymers, amines and ammonium salts of acrylic acid copolymers have also been used, but because emulsions dry quickly9, for example, they may dry on the nib of a writing instrument, or some solvents may There was a problem that the emulsion was 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 conducted by the present inventors as dispersants and drying resistance improvers for the above-mentioned aqueous pigment inks, the inventors found that sorbitan and insorbite are effective as dispersant protective agents and drying resistance improvers. The present invention was completed based on one finding of superiority.

That is, 9 the present invention provides aqueous pigment ink containing sorbitan and/or
Alternatively, the gist of the invention is a water-based pigment ink characterized by containing innorbite.

It is presumed that the hydroxyl groups in the structure of sorbitan and insorbite form hydrogen bonds, which act as a protective effect for various dispersants, thereby contributing to dispersion stability. It is thought that the drying resistance is improved due to its hygroscopic property.

As the pigment, all commercially available pigments can be used, and here are some examples.

Carbon blank, phthalocyanine blue (0,1,7
4160), phthalocyanine green (C,1,74
260), Hansa Yellow 3G, (C, I.

11670), Disazo Yellow GR (0,1,211
00), Permanent Red 4 R, (0,1,123
35), Briantocarmine 6 B (0,1,1s8
50), Quinacridone Red (0,1,46500)
etc. can be used, and the amount used is 5 to 50% of the total amount of ink.
20% by weight is preferred.

Note that the ratio of the type of slope to be used is selected as appropriate.

As the dispersant, various anionic surfactants, nonionic surfactants, acrylic acid copolymers, amines of acrylic acid copolymers, ammonium salts, and resin acids such as ceracta are used.

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

In addition, antiseptic and fungicides such as 1,2-benzointheazolin-3one, pentachlorophenol, and cresolnato, lubricants such as water-soluble silicone oil, and various surfactants can be appropriately selected and used.

The manufacturing method of water-based pigment ink consists of 5-20% by weight of pigment, 01-5% by weight of dispersant, 70-40% by weight of water, 10-30% by weight of water-soluble organic solvent, 1-30% by weight of sorbitan and/or insorbite. %t-,,)'-rumill, roll mill, sand mill.

Mix, grind and disperse using a pigment dispersion machine such as Super Mill, Dyno Mill or Atoniter.

The especially obtained aqueous pigment ink has unprecedented dispersion stability and drying resistance.

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 100 parts Sorbitan 200 parts Propylene glycol 50 parts Ethylene glycol 15.0 parts Shellac 50 parts Caustic soda 05 parts Laurin (manufactured by Daiichi Kogyo Seiyaku ■, anionic surfactant) 0.1 part Emulgen 931 (Kao Atlas ■, nonionic surfactant) 01 parts sodium pentachlorophenol (preservative) 01 parts water 4 7. 2 parts Among the above ingredients, add Ceracta to a mixed solution of water and caustic soda, and stir and dissolve at room temperature.

Then Emulgen 931. Add ethylene glycol and the remaining ingredients one by one, premix with a stirrer for 2 hours,
j! After grinding in a ball mill for 20 hours, coarse particles are removed by filtration or the like.

When the black aqueous pigment ink thus obtained was suction filtered for 100 d using Toyo Roshi Mu 5c, the entire amount passed through the filter paper within 60 seconds.

Almost no residue was observed on the filter paper.

Also, this ink was centrifuged at 5,000 rpm, 30
No sedimentation of the pigment was observed even though it was treated separately.

Furthermore, you can fill a ballpoint pen with this ink, remove the cap, and leave 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 possible.

Comparative Example 1 A water-based pigment ink was obtained in the same manner as in Example 1 except that sorbitan and shellac were removed and water was added. This ink contained many coarse particles and could not be filtered using Toyo Roshi A5c. Further, the pen tip was dried in one day under the same conditions as in Example 1.

Example 2 Steel Phthalo 7 Anine Plue 15.0 parts Insolvite i o, o part Ethylene glycol 15.0 parts Propylene glycol 5.0 parts Shellac 50 parts Caustic soda 10 parts Fouxel G BX (manufactured by 1, O, I company.

anti-mold agent) 01 part Water 50.9 parts As in Example 1, premix after adjustment.

Grinded in a sand mill for 10 hours.

Coarse particles were removed to obtain 1 blue water-based pigment ink.

When 100 ml of this ink was suction filtered through Toyo Roshi A5c, the entire amount passed through the filter paper within 30 seconds, and no residue was observed on the filter paper.

Also, this ink was centrifuged at 5.00 Orpm, 3
Although the treatment was carried out for 0 minutes, no sedimentation of the pigment was observed.

Furthermore, you can fill a ballpoint pen with this ink, remove the cap, and leave 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 possible.

Example 3 Copper phthalone anine blue 10. ON Disano Yellow 5.0 parts Sorbitan 5.0 parts Isosorbite 50 parts Ethylene glycol 20.0 parts Jurimer ET410 (manufactured by Nippon Tsumugi Pharmaceutical Co., Ltd., acrylic ester solid content 29-31%) 10.0 parts Emulgen A-60 (Kao soap, nonionic surfactant) 0.1 part Water 44.9 parts A green water-based pigment ink was obtained in the same manner as in Example 1.

When 100 ml of this ink was suction filtered through Toyo Roshi Layer 5c, the entire amount passed through the filter paper within 50 seconds, and almost no IT residue was observed on the filter paper.

Also, use this ink in a centrifugal separator.

rpm for 50 minutes, but no pigment sedimentation was observed.

Furthermore, you can fill a ballpoint pen with this ink, remove the pen, and leave it in a constant temperature and humidity room at 20°C, 9% humidity, and 65% for 10 days.

The pen tip did not dry out and writing was possible.

As explained above, the aqueous pigment ink of the present invention has excellent monodispersity and monodispersion stability, and has good drying resistance, so it can be particularly used as a low viscosity ink.

Specifically, it can be suitably used for writing instruments using fibers, felt, and monofilament, capillary type writing instruments such as fountain pens, narrow rod type and ball point type writing instruments, and also for recorders, printing, stamps, and jet printers. It can also be applied to printers, etc.

Patent applicant: Pentel Co., Ltd.

Claims (1)

[Claims] A water-based pigment ink characterized by containing sorbitan and/or insorbite.