| 摘要 |
A method of making a cured polyurethane elastomer of the kind which consists in mixing (a) a prepolymer which is a reaction product of a material selected from polyesters, polyethers and polyesteramides with an excess of diisocyanate, and (b) a diamine, and thereafter subjecting the mixture to curing conditions, is characterized by the fact that the said prepolymer is mixed with a crystalline diprimary diamine at a temperature below the melting point of the diamine whereby a mixture having enhanced pot life is obtained, said prepolymer being liquid at the temperature at which it is mixed with the diamine. In one method of carrying out the invention shaped polyurethane elastomers are prepared by reacting a polyester, polyether, or polyesteramide or mixtures thereof, all having acid numbers less than 5, with from 120% to 350% mol of an organic diisocyanate and subsequently mixing the reaction product with a diprimary diamine selected so that its reaction with the particular organic diisocyanate to be employed in semimolar concentration in boiling methylene dichloride causes definite turbidity in less than 25 seconds, and the mixture obtained is shaped and cured by the application of heat. Suitable diamines are naphthalene diamine, 2, 21-diamino-diphenylmethane, benzidine, 4, 41-diamino-diphenyl ether, 2, 4-diamino-toluene, p-phenylene-diamine, diaminoanisole, dianisidine, dichlorobenzidine, o-tolidine and 3, 31-dichloro-4, 41-diamino-diphenylmethane. The polyester, polyether or polyesteramide may be one of those described in Specification 820,005. In Examples (1) a prepolymer from an adipic acid/ethylene glycol/propylene glycol polyester and toluene 2, 4-diisocyanate is mixed at room temperature with naphthalene-1, 5-diamine until the mixture was stiff and putty-like. This is moulded at 140 DEG C.; (4) diphenylmethane diisocyanate and various amounts of p, p1-diaminodiphenylmethane are employed in a similar process. Use of other listed amines is exemplified. Mechanical properties of the products compared with those in which the amine is present in the initial reaction mixture or added above its m.pt. to the prepolymer are tabulated. Specification 858,689 also is referred to.
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