Patent ID: 7344621

Claim:
A method of producing soft paper comprising adding a paper additive composition to pulp, the paper additive composition comprising an amide compound (a) or a salt thereof for softening a paper, wherein the amide compound (a) is obtained by reacting a polyamine and a carboxylic acid, the polyamine is shown by formula (1): R—(NH—R 1 )n-NH 2 (1) wherein R is H 2 N—R 1 or R 2 , and each R 1 is independently an alkylene group having 1 to 4 carbon atoms, R 2 is an alkyl group or alkenyl group having 12 to 22 carbon atoms, and n is an integer of 1 to 3, the number of carbon atoms of the carboxylic acid is 10 to 24, the amide compound is obtained by reacting the carboxylic acid at a ratio of 0.5 to 4.3 moles per 1 mol of the polyamine, wherein the reaction is performed by a first reaction by reacting the polyamine and the carboxylic acid until the acid value of this reaction mixture reaches about 10% of the theoretical acid value of the initial mixture of the polyamine and the carboxylic acid and by a second reaction by allowing the reaction product of the first reaction to proceed until the acid value of this reaction mixture is further reduced to 75% or less of the acid value of the reaction product of the first reaction, and wherein the second reaction is performed under different conditions compared to that of the first reaction, and the ratio of a tertiary amine value to a total amine value of the amide compound (a) is 0.60 to 0.99.