| 摘要 |
A process for preparing a solid polyurethane comprises introducing into a heated inert liquid either (a) the reaction components required to prepare a polyurethane and intimately mixing the components or (b) the premixed components (said components comprising a diisocyanate and a polyhydroxyl compound) maintaining the mixture within the inert liquid until solidification occurs and separating the solidified product from the inert liquid, wherein the inert liquid is a non-solvent, at the temperatures used, for the reaction components and for the product obtained therefrom. The solidified product which has been separated from the inert liquid may be chilled by being passed into an inert liquid having a B.P. below 100 DEG C. which liquid is then evaporated. Inert liquids for the reaction are benzines, mineral spirits of B.P. 160-190 DEG C., kerosene of B.P. 150-280 DEG C., petroleum of B.P. 150-300 DEG C., paraffin oil of B.P. above 300 DEG C., Stoddard solvent, silicone oils and metal alloys, e.g. Wood's metal, Newton's alloy, Lipowitz alloy or mercury. Inert liquids for the chilling step are: petroleum ether, CCl4, benzine, benzene, ethylene trichloride, xylene, acetone or ethyl acetate. Conventional polyurethane precursors are specified including: polyesters, polyesteramides, polyether-polyesters, linear and branched polyethers, polythioethers and polyacetals. Conventional aromatic, aliphatic, cycloaliphatic and heterocyclic diisocyanates are specified. Optionally chain extenders, e.g. glycols, diamines, water, hydrazines and amino-alcohols may be used. In Example (1), butane diol was added to a mixture of polyethylene adipate and diphenylmethane 4,41-diisocyanate and applied to a conveyer band which ran through a bath of silicone oil heated to 90 DEG C. |
