Patent ID: 9701780
Date: 2017-07-11
CPC Classifications: C08G

Claim:
1. A method for preparing a polyurethane, comprising: reacting a polybutadiene having a hydroxyl group at a terminal end thereof with an ε-caprolactone to obtain a polymer polyol of formula (I); reacting the polymer polyol and an unsymmetric diisocyanate to obtain a urethane prepolymer having an isocyanate group at a terminal end thereof, wherein an amount of the unsymmetric diisocyanate is determined so that a molar ratio of a mole number of isocyanate groups derived from the unsymmetric diisocyanate to a mole number of hydroxyl groups derived from the polymer polyol is within a range of 2.1 to 3.8; and then reacting a chain extender with the urethane prepolymer to obtain the polyurethane, wherein an amount of the chain extender is determined so that a molar ratio of the mole number of the isocyanate groups derived from the unsymmetric diisocyanate with reference to a total mole number of hvdroxyl groups derived from the polymer polyol and the chain extender is within a range of 0.9 to 1.1, wherein: X Y represents a polybutadiene component consisting of: wherein a molar ratio of the 1,2-structure/the 1,4-structure is within a range from 90.4/9.6 to 95/5.