Effects of Fine-Particle PR-177 and Co-dispersion with Sulfonic Acid Derivative of PR-177 on Properties of Pigment-Dispersion-Type Color Resist Inks for LCD Color Filters

Abstract

Dispersions of a pigment, 4, 4'-diamino-1, 1'-bianthraquinone (PR-177) were prepered by using and color resist inks using the pigment dispersion for LCD color filters were also prepered. The viscosity and the mean particle size of those pigment dispersions were measured, and the effects of fine-particle PR-177 and the addition of sulfonic acid derivative of PR-177 on the color properties of the resist inks were investigated. The color resist inks prepered with fine-particle PR-177 of which specific surface area was 113.5 m²/g, showeci higher brightness and high contrast ratio, but the viscosity and thixotropy index (TI value) of the pigment dispersions increased. Viscosity and TI value of the dispersions were improved by the addition of the sulfonic acid derivative. The addition of the sulfonic acid derivative to the standard PR-177, of which specific surface area was 90.7 m²/g, in the lowering of the viscosity, showed an adequate improvement while it showed little effect on the fineparticle PR-177. When the fraction of the sulfonic acid derivative exceeded 5%, haze was found on the surfaces of both the ink films prepared with the standard and the fine-particle PR177s, which remained as a subject to be improved.