Preparation method for polyurethane elastomers

The invention discloses a preparation method for polyurethane elastomers. Prepolymers are formed after reaction of copolymer-type polyether diol, copolymer-type polyeaster diol and isocyanate, then polyurethane elastomers are obtained after further chain extension and curing with chain extenders. The preparation method for the copolymer-type polyether diol is as follows: one or a mixture of at least two of ethylene oxide, epoxy propane, tetrahydrofuran and trioxymethylene at a mass ratio of (60-95):(5-40) are added in a reactor and stirred, a catalyst weighing 0.1-5% of the total mass of the above reactants are slowly added in the reactor in 30min, the reaction temperature is controlled at 40-50 DEG C, then the mixture is stirred for 4-5h for reaction, reaction products are neutralized with a NaOH aqueous solution with a mass concentration of 4-6%, the reaction products are further subjected to water washing until the reaction products are neutral, and the copolymer-type polyether diol is obtained after vacuu