| 摘要 |
1,203,674. Stabilized polyurethanes. AMERICAN CYANAMID CO. 22 April, 1968 [26 May, 1967], No. 18965/68. Heading C3R. Polyether based polyurethanes are stabilized against thermal degradation by the presence of a phenothiazine compound of the formula wherein R is alkyl of 1 to 18 carbon atoms, alkoxy of 1 to 18 carbon atoms, halogen or alkylmercapto of 1 to 18 carbon atoms and R<SP>1</SP> is hydrogen or any one of the substituents given in the definition of R. The stabilizer may be added to the prepolymer prior to chain extension or swelled into the fully extended elastomer at a later stage. Preferred concentrations of the phenothiazine compound are from 0.05 to 5.0 parts by weight based on the weight of the polyurethane. In specific examples the stabilizers used are 2 - chloro - 4 - thiomethyl -, 2 - methoxy -, 4 - chloro - and 3,7 - dioctyl - phenothiazine. Reference has been directed by the Comptroller to Specification 1,124,683. |
