| 摘要 |
A method for the preparation of a polyurethane having from 0.2 to 5.0% by weight of polyethylene and/or polypropylene having a melt index of at least 115 and a molecular weight of from 1000 to 500,000 dispersed substantially uniformly therein comprises pouring a polyurethane melt on to a sheet of the said polyolefin, allowing the polyurethane to cool with the polyolefine sheet adhered thereto, cutting and chopping the resultant laminate and thereafter reducing the particle size and blending the polyurethane and polyolefine. In a modification of the process, the polyurethane is formed between two sheets of the polyolefine. Specified polyurethanes are those derived from polyesters, polyesteramides, polyalkylene ethers, polythioethers or polyacetals and diisocyanates optionally in the presence of chain-extending agents e.g. glycols, diamines, hydrazine, polyhydrazides, bis-semi carbazides, biscarbazides and water, many suitable reactants being specified.ALSO:A method for the preparation of a coated polyolefin comprises pouring a polyurethane melt onto a sheet of polyethylene and/or polypropylene having a melt index of at least 115 and a molecular weight of from 1,000 to 500,000 and allowing the polyurethane to cool. The resultant product is then reduced to particulate form. |
