Process for producing neutral to alkali color developer pigments

US5637552A · kind A · utility

Assignee

• Sud-Chemie A.G. · DE

Inventors

• Reinhard Hahn · Vilsheim, DE
• Friedrich Ruf · Ramstein-Miesenbach, DE

Key dates

• Filing date: Jun 13, 1995
• Grant date: Jun 10, 1997
• Expiry date: Jun 13, 2015

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01P2006/60
• WIPO field: Basic materials chemistry
• WIPO sector: Chemistry

Abstract

A process is described for producing neutral to alkaline color developer pigments for use in carbon-free transfer papers from an acid-activated smectic phyllosilicate and basically reacting chemicals. The process is characterized in that the acid-activated phyllosilicate with a layer structure which is essentially still intact is reactive without intermediate drying with the basically-reacting chemicals up to partial or complete decomposition of the amorphous silicic acid formed on the corners and edges of the phyllosilicate crystallites without significant re-exchange of the hydronium ions inserted between the layers of the phyllosilicate by alkali or earth alkali ions. The color developer pigments can be used in suspensions with concentrations from 30 to 50% by weight, preferably from roughly 38 to 48% by weight.