Thermoplastic polyurethane resin and its manufacturing method has a wide rubber area

摘要

Disclosed is a polyurethane resin having a broad rubbery-state region which has a number-average molecular weight of from 30,000 to 500,000 and comprises repeating units (A) represented by formula (I): -CONH-X-NHCOO-Y-O-(I) wherein X represents the divalent residue formed by removing the isocyanate groups from a specific aromatic diisocyanate and Y represents the divalent residue formed by removing the hydroxyl groups from a poly(alkylene ether) diol whose main chain is made up of the group represented by -CH2CH2CH2CH2O- and a group represented by -CHR1CHR2CHR3CHR4O- where one of R1, R2, R3, and R4 is a lower alkyl group and the remaining three each is a hydrogen atom, and which has a number-average molecular weight of from 500 to 10,000, and repeating units (B) represented by formula (II): -CONH-X-NHCOO-Z-O-(II) wherein Z represents the divalent residue formed by removing the hydroxyl groups from 3,9-bis(1,1-dimethyl-2-hydroxyethyl)-2,4,8,10-tetraoxaspiro[5,5]undecane), the repeating units (A) and (B) being bonded together in a random sequence, with the proportion of (A)/(B) being from 0.1 to 2.0.