| 摘要 |
PURPOSE:To improve the wet process film formability, surface smoothness, etc., of a porous sheet material, by adding a specified aluminum compound to a polyurethane solution in the production of a porous sheet material by applying the polyurethane solution to a substrate and treating it by a wet proc ess. CONSTITUTION:A polyurethane solution is prepared by reacting an organic diisocyanate with a polymer diol and, optionally, a chain extender (e.g., ethylenediamine). This polyurethane solution is mixed with an aluminum compound of formula I (wherein R1, R2, R3 and R4 are each a 1-20C aliphatic hydrocarbon and R is H or a 1-20C aliphatic hydrocarbon),e.g., formula II (wherein R4 is formula III) in an amount of 0.05-5wt%, based on the solid matter of the polyurethane solution. This polyurethane solution is applied to a substrate and the applied solution is treated by a wet process to obtain a porous sheet material having excellent surface smoothness, a low sheet density and a low shrinkage.
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