JPS62101672A - Water-based pigment ink for writing utensil - Google Patents

Abstract

PURPOSE:To provide the titled ink which is highly hygroscopic, has excellent drying resistance and dispersion stability and does not cause the clogging of nibs, by blending water-based pigment ink consisting of a pigment, a dispersant, water, etc. with sorbitan and/or sorbitol as dispersion stabilizers. CONSTITUTION:40-85wt% water as a principal ingredient is blended with 5-20wt% pigment (A) such as carbon black, phthalocyanine blue, etc., 2-20wt% dispersant (B) such as a high-molecular dispersant (e.g., a salt of a styrene/ acrylic acid copolymer), a surfactant (e.g., a sorbitan alkyl ester), etc., 5-40wt% sorbitan and/or sorbitol (C) as dispersion stabilizers and optionally, org. solvents such as glycols, urea (derivative), a preservative, a rust inhibitor, etc. (D).

Description

Detailed Description of the Invention (Industrial Application Field) The invention relates to a water-based pigment ink used for writing instruments, and more specifically, an aqueous pigment for writing instruments that has excellent clogging resistance and drying resistance in the pen tip. It concerns ink.

(Prior Art) Dye inks have conventionally been used as water-based inks for writing instruments, but pigment inks are becoming mainstream because the water resistance and light resistance of handwriting are poor.

(Problems to be Solved by the Invention) However, the above-mentioned pigment ink has problems such as insufficient dispersion stability over time, clogging of the pen nib over time, and the tendency of the pen nib to dry if the cap is removed and left unattended. It had a point.

(Means for Solving the Problems) The present inventors have completed the present invention as a result of intensive research to solve these problems. That is, the gist of the present invention is an aqueous pigment ink for writing instruments containing at least a pigment; a dispersant; sorbitan and/or nrbitol; and water.

(Structure of the Invention) The water-based pigment ink for writing instruments of the present invention will be described in detail below.

The pigment is used as a coloring material, and generally commercially available pigments can be used, but specifically, carbon blank (C, 1, 77265) is used.

Phthalocyanine Blue (C, L74160), Phthalocyanine Green (C, 1,74260), Hansa Yellow 3G (C, 1,11670), Disazo Yellow GR (
C, 1, 21100), Permanent Red 4 R (C
, 1,12335), Brilliant Carmine 6 B
(C,1,15850), Quinacridone Red (C,
1,46500), etc., or two or more thereof can be appropriately selected and used. The amount used is 5 to 2 for the total amount of ink.
0% by weight is desirable. 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. Cellulose derivatives such as glucoids, methylcellulose, carboxycellulose, and hydroxymethylcellulose.

Natural polymers such as lignin sulfonate and shellac, polyacrylate salts of di-styrene-acrylic acid copolymer, salts of vinylnaphthalene-acrylic acid copolymer, styrene-
Salts of maleic acid copolymers, salts of vinylnaphthalene-maleic acid copolymers, salts of β-naphthalenesulfonic acid formalin condensates, anionic polymers such as rum salts and phosphates, polyvinyl alcohol, and polyvinylpyrrolidone. , polymeric dispersants such as nonionic polymers such as polyethylene glycol, surfactants such as anionic surfactants such as fatty acid salts, higher alcohol sulfate ester salts, liquid fatty oil sulfate ester salts, and alkylaryl sulfonates. .

Nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters, one or more of these may be selected as appropriate. It can be used as The amount used is preferably 2 to 20% by weight based on the total amount of ink.

Sorbitan and/or sorbitol, which is the essence of the present invention, is used as a dispersion stabilizer, and the amount used is 5 to 4% by weight, preferably 10 to 4% by weight, based on the total amount of the ink.
It is 55% by weight.

If it is less than 5% by weight, the effect will be insufficient, and if it is more than 40% by weight,
It has no further effect. Water is used as the main solvent, and is preferably 40 to 85% by weight based on the total amount of the ink. In addition to the above ingredients, organic solvents such as glycols, cellosolves, carbitols, urea and its derivatives, thiourea and its derivatives, 2 ethylene urea and its derivatives, and preservatives and anti-molds may be used to improve the characteristics of the writing instrument. drugs,
Rust preventives, Himadera Kiba, etc. may be selected and used as appropriate.

Next, there is a method for producing a water-based pigment ink for writing instruments of the present invention.
- The above-mentioned components are dispersed in a conventional dispersion machine 2 such as a ball mill, a roll mill, a Santo mill, or a Suham mill.

It can be easily obtained by mixing, grinding and dispersing using a dyno mill, attritor, etc., and then removing coarse particles of the pigment by a method such as p-filtration or centrifugation.

(Effects) It is not clear why the water-based pigment ink for writing instruments of the present invention has excellent dispersibility, but the high protective colloidal properties of sorbitan and/or sorbitol prevent pigment aggregation and prevent clogging of the pen tip over time. In addition, since sorbitan and sorbitol have very strong hygroscopic properties, it is presumed that the dryness of the pen tip when the cap is removed and left standing is also improved.

(Example) Example 1 Carbon black (C, 1,77265) 10.0 parts Styrene-acrylic acid amine salt (dispersant) 50 parts Sorbitol 25.0 parts Water
60.0 parts The above components were blended and dispersed in a ball mill, and then coarse particles were removed using a filter or the like to obtain a black ink.

Comparative Example 1 A black ink was obtained in the same manner as in Example 1, except that sorbitol in Example 1 was removed and propylene glycol was added in the same amount.

Example 2 Phthalo/Anine Blue (CI74160) aO part styrene-maleic acid ammonium salt (dispersant)
ZO0 part sorbitan
20.0 parts ethylene glycol
10.0 parts water
50.0 parts of the above ingredients in Example 1
Blue ink was obtained in the same manner as above.

Comparative Example 2 A blue ink was obtained in the same manner as in Example 2, except that sorbitan in Example 2 was removed and ethylene glycol was added in the same amount.

Example 6 Permanent Renod 4R (C112335) 10
．． 0 parts styrene-maleic acid amine salt (dispersant) 10.0 parts sorbitan 15.0 parts sorbitol
15.0 parts Pentachlorophenol sodium salt (preservative)
01 part water
49.9 parts A red ink was obtained using the same ingredients as in Example 1.

Comparative Example 6 A red ink was obtained in the same manner as in Example 3, except that sorbitan in Example 3 was removed and ethylene glycol was added in the same amount, and sorbitol was removed and glycerin was added in the same amount.

(Effect) Examples 1 to 6 above. The inks obtained in Comparative Examples 1 to 3 were filled into a commercially available felt-tip pen (Bentel Signature Pen 5520, manufactured by Bentel ■), and the clogging over time and pen tip drying resistance tests were conducted. The results are shown in Table 1. show.

Table 1 ゛〈1. After leaving the product that has become clogged over time with the cap facing down in a constant temperature room at 50°C,
Write in circles on ISP3201 writing paper A and visually determine whether there are any scratches.

*2 After removing the drying-resistant pen tip cap and leaving it indoors, write in circles in the same manner as the above-mentioned time-lapse clogging test every hour and visually judge whether there is any smearing.

As described above, the ink of the present invention has excellent dispersion stability when used in writing instruments, and prevents clogging of the pen tip over time.

It is a water-based pigment ink for writing instruments that has excellent nib drying resistance and is effective for use not only in felt-tip pens but also in plastic nib and ballpoint pens.

Claims (1)

[Claims] Pigment ink for writing instruments containing at least pigment; dispersant; sorbitan and/or sorbitol; water