AUFZEICHNUNGSPAPIER

摘要

A recording sheet consisting mainly of fibrous material is capable of displaying a colored image when contacted under pressure with substantially colorless crystal violet lactone and similar dye precursors if at least 3% of the fibrous material is constituted by uniformly distributed asbestos fibers. Sheets having adequate strength for carbonless copying should not contain more than 30% asbestos fibers. Stronger colors are obtained if the sheet further contains a mixture of gamma -alumina and gamma -alumina precursors in an amount of 2% to 20% of the weight of the fibrous material, the mixture containing 1% to 30% water volatile at 1000 DEG C, and being converted substantially entirely to gamma -alumina when heated from 300 DEG to 1000 DEG C.