Claims
- 1. A water base pigment ink composition for use in marking pens which contain an absorbent ink reservoir and a pen tip connected thereto, the ink composition comprising:
- (a) water in amounts of not less than 50% by weight;
- (b) an aqueous emulsion of hollow resin particles in amounts of 0.5-40% by weight as solids;
- (c) a pigment in amounts of 1-40% by weight; and
- (d) a dispersant composed of one or more water-solubilized and/or water soluble organic polymeric resins, which dispersant has a weight average molecular weight of 1000-10000 and a distribution of molecular weight of 0.5-3.3, but which contains substantially no components having a weight average molecular weight of not more than 500, in amounts of 0.1-30% by weight, based on the ink composition, respectively, said ink composition having a thixotropic structure.
- 2. A water base pigment ink composition as claimed in claim 1, wherein the pigment is white.
- 3. A water base pigment ink composition as claimed in claim 1, wherein the hollow resin particles have a specific gravity of not more than one, a particle size of 0.1-1.0 mu and a refractive index of 1.4-1.6.
- 4. A water base pigment ink composition as claimed in claim 2, wherein the white pigment is titanium dioxide or zinc oxide.
- 5. The water base pigment ink of claim 1 wherein said dispersant comprises alpha-methylstyrene/styrene/acrylic acid copolymer.
REFERENCE TO RELATED APPLICATIONS
The present application is a division of patent application Ser. No. 07/535,328, filed June 8, 1990, now U.S. Pat. No. 5,009,536, which is a division of application Ser. No. 07/434,945, filed Nov. 9, 1989, now U.S. Pat. No. 4,942,185, granted July 17, 1990.
US Referenced Citations (1)
Number |
Name |
Date |
Kind |
4942185 |
Inoue et al. |
Jul 1990 |
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Divisions (2)
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Number |
Date |
Country |
Parent |
535328 |
Jun 1990 |
|
Parent |
434945 |
Nov 1989 |
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