Abstract: A collagen powder is obtained by wet-pulverizing a purified animal tissue consisting mainly of collagen in water at a collagen concentration of 1-30% by weight at a water temperature of not more than 37.degree. C. and a pH value of 2-8, tanning treating the pulverized tissue at a pH level of 2-7 with a polyvalent metal tanning agent to obtain a stabilized wet collagen product, dehydrating the wet collagen product at a pH level of 4-8, and then drying and pulverizing the dehydrated product into a powder. This powder can be used as an additive for modifying paints, artificial leathers, molding materials and the like based on synthetic resins such as thermoplastic resins. The materials obtained with this powder have an excellent appearance, feel, and moisture-absorbing and moisture-releasing properties.

Abstract: Disclosed is a collagen powder having a good dispersion stability, in which the content of particles having a particle size smaller than 40 .mu.m is at least 85% by weight, the water absorption is 120 to 300%, and the apparent bulk density is 0.10 to 0.30 g/cc. This collagen powder is advantageously used for a leather-like surface layer-forming agent and a leather-like molded article.

Abstract: A fluoran derivative useful for a heat-sensitive recording material, having the following general formula I; ##STR1## wherein R.sub.1 and R.sub.2, which may be the same or different, stand for an alkyl group having 1 to 9 carbon atoms, a cycloalkyl group having 3 to 6 carbon atoms, a phenyl group or a phenyl group substituted by an alkyl group having 1 to 4 carbon atoms, and R.sub.3 and R.sub.4, which may be the same or different, stand for an alkyl group having 1 to 6 carbon atoms or a phenyl group or R.sub.3 and R.sub.4 may form a 5- to 8-membered cycloalkane together with the carbon atom to which they are bonded.

Abstract: An agent for forming a surface-protecting layer on a coated paper, which comprises an aqueous solution of an alkali metal salt, ammonium salt or amine salt of a graft copolymer and an epoxy group-containing cross-linking agent incorporated in the aqueous solution, said graft copolymer comprising (A) 10 to 60% by weight of a polyvinyl alcohol polymer selected from the group consisting of partially saponified polyvinyl alcohols, polyvinyl alcohols containing copolymerized units of a vinyl monomer having carboxyl group, and polyvinyl alcohol having the recurring vinyl alcohol units esterified with a higher fatty acid, (B) 20 to 70% by weight of acrylamide or methacrylamide, (C) 5 to 30% by weight of at least one member selected from the group consisting of acrylonitrile, methacrylonitrile, lower alkyl esters of acrylic acid and methacrylic acid and hydroxyl lower alkyl esters of acrylic acid and methacrylic acid, and (D) 5 to 20% by weight of at least one vinyl monomer containing a carboxyl group.