Process for coating porous material with a microporous elastomeric polymer dissolved in a volatile mixture of a ketone and a volatile aliphatic hydrocarbon

Claim 1

A PROCESS FOR COATING COARSELY POROUS MATERIAL WITH A SPONGE-LIKE AND POROUS FILM PERMEABLE TO WATER VAPOR, WHICH PROCESS COMPRISES SPRAY COATING SAID COARSELY PROOUS MATERIAL WITH A POLYMERIC ELASTOMER SELECTED FROM THE GROUP CONSISTING OF POLYCHLOROPRENE, BUTRADIENE-STYRENE COPOLYMER, CHLOROSULFONATRED POLYETHYLENE COPOLYMER, BUTADIENE-ACRYLONITRILE COPOLYMER AND VINYLIDENE FLUORIDEHEXAFLUOROPROPENE COPOLYMER, SAID ELASTOMER BEING DISSOLVED IN A VOLATILE MIXTURE OF (1) A KETONE SELECTED FROM THE GROUP CONSISTING OF ACETONE AND METHYL ETHYL KETONE, AND (2) A VOLATILE ALIPHATIC HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF N-HEXANE AND N-PENTANE, SAID VOLATILE ALIPHATIC HYDROCARBON HAVING A VAPOR PRESSURE DIFFERENT FROM THAT OF SAID KETON, SAID MIXTURE CONTAINING FROM ABOUT 20 TO 65% OF SAID KETONE, THE SOLUTION OF SAID ELASTOMER IN SAID VOLATILE MIXTURE HAVING A VISCOSITY WITHIN THE RANGE OF 100 TO 400 CONTIPOISES.