| 摘要 |
A cold. hardenable binder for moulding material, based on: polyurethane, for mixts. of materials to be used to make moulds and cores, consits of a polyisocyanate with is not 2 NCO gps. and a polyol with is not 2 OH gps., the polyol being an aminopolyol which contains is not 1 tert-amino gp. actign as an accelerator. Cold hardenable moulding materials harden very slowly unless na unacceptably large amt. of accelerator is present. Materials contg. polyurethanes can be hardened by treatment for short times with tert-amine in gaseous state e.g. triethylamine, but this has deleterious effects on moulded prods. of large size. The present method gives much more rapid hardening without deleterious effects, the accelerator being one of the agents used in the system. No toxic or otherwise obnoxious effects are prod. |
