| 摘要 |
PURPOSE:To obtain a polyurethane foam having good air permeability, by applying an org. solvent to a non-rigid polyurethane foam sheet having a specified number of cells and specified air permeability and blowing compressed air thereon to remove cell membranes. CONSTITUTION:An org. solvent is applied to a non-rigid polyurethane foam sheet having such open cells that the number of cells is 50 cells/25mm or below and air permeability is 80cc/sec/cm<2> or above the allow it to swell. Compressed air is blown thereon to remove cell membranes. Examples of the org. solvents are halogenated hydrocarbons, aliph. hydrocarbons, arom. hydrocarbons, alcohols and ketones. They may be used either alone or as a mixture thereof. Low- boiling halogenated hydrocarbons are particularly preferred from the viewpoints of activity and workability. The resulting foam has greatly improved air and liquid permeabilities and hence it can be used as a filter.
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