JPH0562634B2 - - Google Patents

Description

[Detailed description of the invention]

(Industrial Application Field) The present invention relates to a water-based pigment ink for use in writing instruments, and more particularly to a water-based pigment ink for writing instruments that has excellent clogging resistance and drying resistance in the pen tip. (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 drying of the nib 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, sorbitol, and water. (Structure of the Invention) The water-based pigment ink for writing instruments of the present invention will be described in detail below. Pigments are used as colorants, and commonly commercially available pigments can be used, but specific examples include Carbon Black (CI77265), Phthalocyanine Blue (CI74160), Phthalocyanine Green (CI74260), and Hansa Yellow 3G (CI11670). ), Diaszo Yellow GR (CI21100), Permanent Red 4R (CI12335), Brilliant Carmine 6B (C.
I.15850), Quinacridone Red (CI46500), etc., or two or more thereof can be appropriately selected and used.
The amount used is preferably 5 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 shellac, polyacrylates, salts of styrene-acrylic acid copolymers, vinylnaphthalene-acrylic acid copolymers salts of styrene-maleic acid copolymers, salts of vinylnaphthalene-maleic acid copolymers, sodium salts of β-naphthalenesulfonic acid formalin condensates, anionic polymers such as phosphates, polyvinyl alcohol, Polymer dispersants such as nonionic polymers such as polyvinylpyrrolidone and polyethylene glycol, surfactants such as anionic interfaces such as fatty acid salts, higher alcohol sulfate ester salts, liquid fatty oil sulfate ester salts, and alkylaryl sulfonates. There are active agents, nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, and polyoxyethylene sorbitan alkyl esters, and one or two of these
More than one species can be selected and used as appropriate. The amount used is preferably 2 to 20% by weight based on the total amount of ink. Sorbitol, which is the essence of the present invention, is used as a dispersion stabilizer, and the amount used is 5 to 40% by weight, preferably 10 to 35% by weight, based on the total amount of the ink. If it is less than 5% by weight, the effect will be insufficient, and 40
If the amount is more than % by weight, there is no further effect. Water is used as the main solvent, and is preferably 40 to 85% by weight based on the total amount of ink. In addition to the above ingredients, organic solvents such as glycols, cellosolves, carbitols, urea and its derivatives, thiourea and its derivatives, ethylene urea and its derivatives, and preservatives and anti-molds may be used to improve the characteristics of the writing instrument. An agent, a rust preventive agent, etc. may be selected and used as appropriate. Next is the method for producing the aqueous pigment ink for writing instruments of the present invention. The ink is prepared by mixing, grinding, and dispersing the above-mentioned components using a conventional dispersing machine such as a ball mill, roll mill, sand mill, super mill, dyno mill, attritor, etc. However, it can be easily obtained by further removing coarse particles of the pigment by a method such as 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 sorbitol prevent pigment agglomeration and prevent clogging of the pen tip over time. Since sorbitan, sorbitol, and sorbitol have very strong hygroscopic properties, it is presumed that they also improve the drying properties of the pen tip when the cap is removed and the pen is left standing. (Example) Example 1 Carbon black (CI77265) 10.0 parts Styrene-acrylic acid amine salt (dispersant)
5.0 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 Permanent Red 4R (CI12335) 10.0 parts Styrene-maleic acid amine salt (dispersant)
10.0 parts Sorbitan 15.0 parts Sorbitol 15.0 parts Pentachlorophenol sodium salt (preservative) 0.1 part Water 49.9 parts A red ink was obtained using the above ingredients in the same manner as in Example 1. Comparative Example 2 A red 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, and sorbitol was removed and glycerin was added in the same amount. (Effects) The inks obtained in Examples 1 and 2 and Comparative Examples 1 and 2 were applied to a commercially available felt-tip pen (Pentel felt-tip pen).
S520 (manufactured by Pentel Co., Ltd.), and it becomes clogged over time.
Table 1 shows the results of the pen nib drying resistance test.

【table】

[Table] As described above, the ink of the present invention has excellent dispersion stability when used in writing instruments, and is excellent in resistance to clogging of the nib over time and drying of the nib. , is a water-based pigment ink for writing instruments that is also effective when used in ballpoint pens.

Claims (1)

[Claims] 1. A water-based pigment ink for writing instruments containing at least a pigment, a dispersant, sorbitol, and water.