Abstract: A heat-sensitive recording sheet has A heat-sensitive recording layer containing color formers and color developers formed on one side of a substrate, a backcoat is formed on the side opposite to the recording layer, wherein this backcoat is formed of A mixture containing starch, an acrylate copolymer which does not comprise styrene or vinyl acetate components and has a film-forming temperature of less than 5° C., and an alkaline catalyst.

Abstract: 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.degree. C, and being converted substantially entirely to .gamma.-alumina when heated from 300.degree. to 1000.degree. C.

Abstract: A mixture of .gamma.-alumina and its precursors containing 1 to 30% water volatile at 1000.degree. C converts normally colorless dye materials such as crystal violet lactone, malachite green lactone, benzoyl leuco methylene blue and N-phenylleukauramine to the corresponding colored dyes upon contact, and improves the results achieved with recording material consisting essentially of a fibrous web and a pigment composition secured to the fibers of the web if the mixture amounts to at least 10% of the weight of the pigment composition. Particularly strong and stable colors are produced if the fibrous web is coated with a pigment composition prepared from an aqueous dispersion of the mixture and other pigments on which a basic compound is deposited from a water-soluble zinc salt by means of hydroxyl ions.