Patent ID: 8222311

Claim:
A method for preparing a polyurethane resin, comprising: reacting a polyalkylene polyamine represented by a following general formula (4): wherein R 1 to R 4 are hydrogen atoms; R 5 is a hydrogen atom or a C 1 to C 3 alkyl group; when R 5 is a C 1 to C 3 alkyl group, R 5 and R 1 , R 2 , R 3 , or R 4 may arbitrarily bond together to form a ring; n and m are independently an integer from 1 to 5; and a is an integer from 1 to 6; with an N-alkylating agent while varying a molar ratio of the polyalkylene polyamine to the N-alkylating agent to obtain at least two kinds of N-alkylated polyalkylenepolyamines; adding an alkylene oxide to the at least two kinds of N-alkylated polyalkylene polyamines to obtain a hydroxyalkylated polyalkylene polyamine composition comprising at least two kinds of hydroxyalkylated polyalkylene polyamines represented by the following general formula (1): wherein R 1 to R 5 are independently a C 1 to C 3 alkyl group or a substituent represented by the following general formula (2): wherein R 6 and R 7 are independently a hydrogen atom or a C 1 to C 4 alkyl group, and p is an integer from 1 to 3, and R 5 and R 1 , R 2 , R 3 , or R 4 may arbitrarily bond together to form a ring; at least one of R 1 to R 5 is a substituent represented by the general formula (2) but all of R 1 to R 5 cannot be substituents represented by the general formula (2) at the same time; n and m are independently an integer from 1 to 5; and a is an integer from 1 to 6; and reacting a polyol and an isocyanate in the presence of the hydroxyalkylated polyalkylene polyamine composition.