Heat-sensitive recording material

Claim 1

A heat-sensitive recording material comprising a base sheet, a heat-sensitive record layer formed over the base sheet and containing a color forming material and a color developing material which undergoes a color forming reaction on contact with the color forming material, and a protective layer formed over the heat-sensitive record layer and comprising a water-soluble resin, the heat-sensitive recording material being characterized in that the protective layer contains at least one member selected from the group consisting of: (i) polyaluminumhydroxide represented by the formula [Al.sub.2 (OH).sub.a X.sub.6-a ].sub.n (I) wherein X represents halogen ion or NO 3 - , 0<a<6 and 1<n≦20, (ii) polyaluminumhydroxide represented by the formula [Al.sub.2 (OH).sub.a (SO.sub.4).sub.(6-a)/2 ].sub.n (II) wherein a and n are as defined above, and (iii) a metal salt of unsaturated aliphatic carboxylic acid represented by the formula M.sub.b A.sub.c Y.sub.d (III) wherein M represents a metal having a valence of 2, 3 or 4, A represents unsaturated aliphatic carboxylic acid residue formed by removing one or two hydrogen atoms from the carboxyl group or groups of unsaturated aliphatic monocarboxylic acid or unsaturated aliphatic dicarboxylic acid, Y represents halogen ion, OH - , SO 4 2- or NO 3 - , b is an integer of 1 or 2, c is an integer of 1 to 8, d is 0 or an integer of 1 to 8, with the proviso that ck.sub.2 +dk.sub.3 =bk.sub.1 wherein k 1 , k 2 and k 3 are the valences of M, A and Y, respectively.