| 摘要 |
1,253,602. Rigid foam products. FARBENFABRIKEN BAYER A.G. 5 May, 1969 [17 May, 1968], No. 22738/69. Headings C3C and C3R. Rigid foam products which have a dense outer skin and a core of lower density and an overall density of 0-15 g/cm.<SP>3</SP> to 0-04 g/cm.<SP>3</SP> are produced by foaming in a closed mould a reaction mixture comprising a polyisocyanate, a compound containing reactive hydrogen atoms and as blowing agent an organic solvent in a quantity of at least 70 parts by weight per 100 parts by weight of the compound which contains reactive hydrogen atoms. Polyurethanes are suitably produced by reacting a diisocyanate with a polyether or polyester polyol. Water may be used as an additional blowing agent. Suitable blowing agents are trichloromonofluoromethane, dichlorodifluoromethane and methylene chloride. Catalysts, stabilizers and flame-retarding agents may be included in the reaction mixture. It is preferred to carry out the reaction by compacting the reaction mixture in a mould which is at normal temperature or which is slightly cooled. |
