| 摘要 |
Polyurethane elastomer molded parts obtainable by casting process comprises reacting (a) isocyanate prepolymers with a viscosity at 80[deg] C of less than 3000 mPas, with an isocyanate content (3-7 wt.%) and with a proportion of free monomeric 2,4'-diphenylmethane diisocyanate (1- 6 wt.%), based on the isocyanate prepolymer, obtainable by reacting diphenylmethane diisocyanate with a 2,4'-isomer content of at least 95 wt.% and polyols with hydroxide numbers of 50-180 m potassium hydroxide/g and a functionality of 2, where the ratio, is 1.6:1-2.1:1. Polyurethane elastomer molded parts obtainable by casting process comprises reacting (a) isocyanate prepolymers with a viscosity at 80[deg] C of less than 3000 mPas, with an isocyanate content (3-7 wt.%) and with a proportion of free monomeric 2,4'-diphenylmethane diisocyanate (1- 6 wt.%), based on the isocyanate prepolymer, obtainable by reacting diphenylmethane diisocyanate with a 2,4'-isomer content of at least 95 wt.% and polyols with hydroxide numbers of 50-180 m potassium hydroxide/g and a functionality of 2, where the ratio, is 1.6:1-2.1:1, with (b) complexes of 4,4 '-diaminodiphenylmethane and metal salts, in the presence of (c) optionally auxiliaries and additives, and (d) optionally plasticizers. An independent claim is also included for producing polyurethane elastomer moldings by the casting process comprising; mixing (i) isocyanate prepolymers with a viscosity at 80[deg] C of less than 3000 mPas, with an isocyanate content (3-7 wt.%) and with a proportion of free monomeric 2,4'-diphenylmethane diisocyanate (1- 6 wt.%), based on the isocyanate prepolymer, obtainable by reacting diphenylmethane diisocyanate with a 2,4'-isomer content of at least 95 wt.% and polyols with hydroxide numbers of 50-180 mg of potassium hydroxide/g and a functionality of 2, where the ratio, is 1.6:1-2.1:1, (b) complexes of 4,4 '-diaminodiphenylmethane and metal salts, (c) optionally auxiliaries and additives, and (d) optionally plasticizers; (ii) optionally storing the reaction mixture resulted in step (i) at = 70[deg] C; (iii) pouring the reaction mixture into a mold; (iv) curing the reaction mixture at 80-150[deg] C to form polyurethane and (v) removing the cured polyurethane from the mold as a molded part. |
