REDUCED CHARGE MONTMORILLONITE PIGMENT AND USE IN RECORD RIAL

摘要

A sheet coated with a reduced charge montmorillonite pigment for use in record material, especially pressure-sensitive carbonless copying systems. The pigment is produced by replacing exchangeable cations of a substantially dioctahedral montmorillonite(exemplified by certain bentonite clays) with a preselected quantity of lithium ions, mildly heating the lithium-exchanged montmorillonite to collapse irreversibly the montmorillonite structure, and grinding the heat-treated material to pigment-size particles. The sheets produce stabilized intense images when printed with a solution of crystal violet lactone (CVL) dye precursor and thus may be used with CVL without employing secondary slow acting dyes such as benzoyl leuco methylene blue. The sheets are also useful with other colorless or substantially colorless dye precursors.