Manufacture of rigidized convoluted foam from flexible polyurethane foam and resultant product

摘要

A rigidized convoluted foam suitable as a self-standing filter is made by passing a sheet of air-permeable flexible polyurethane foam through a convoluting machine to obtain two unnested sheets of convoluted foam, each sheet being convoluted on only one side. The two sheets are nested and impregnated from the flat surface of each sheet almost to the closest valley surface with a thermosetting melamine, urea, or benzoguanamine resin in an amount to not appreciably impair the permeability of the foam and to increase the rigidity of the foam sufficiently so that each unnested sheet will be self-standing. After the resin has reacted, the nested sheets are separated.