초록 ▼

The present invention relates to breathable, waterproof sheet materials comprising a microporous polymeric film and a hydrophilic filler material infiltrated into the pores of the film, and to methods for making such sheet materials. In the methods of the present invention, the liquid hydrophilic ma

The present invention relates to breathable, waterproof sheet materials comprising a microporous polymeric film and a hydrophilic filler material infiltrated into the pores of the film, and to methods for making such sheet materials. In the methods of the present invention, the liquid hydrophilic material or precursor thereof is infiltrated into the pores of the microporous film after the film has been stretched in the lengthwise direction, but before the film is stretched in the transverse direction. By coating the microporous film prior to the transverse stretching step, superior waterproof sheet materials are obtained.

대표청구항 ▼

A unitary sheet material made according to a method comprising the steps of: preparing a sheet of polymeric material, said preparing step comprising: melt blending to form a solution comprising a crystallizable thermoplastic polymer and a compound with which said thermoplastic polymer is miscible an

A unitary sheet material made according to a method comprising the steps of: preparing a sheet of polymeric material, said preparing step comprising: melt blending to form a solution comprising a crystallizable thermoplastic polymer and a compound with which said thermoplastic polymer is miscible and in which said thermoplastic polymer will dissolve at the melting temperature of said thermoplastic polymer but which will phase separate on cooling to a temperature at or below the crystallization temperature of said thermoplastic polymer; forming a sheet from the melt blended solution; and cooling said sheet to a temperature at which said thermoplastic polymer crystallizes to cause phase separation to occur between said compound and said polymer, thereby providing said sheet with an aggregate of a first phase comprising particles of crystallized thermoplastic polymer in a second phase comprising said compound with adjacent thermoplastic polymer particles being distinct but having a plurality of zones of continuity; stretching said polymeric sheet in a first direction so as to render said sheet more microporous; coating said polymeric sheet, after said polymeric sheet has been stretched in the first direction, with a liquid filler material which is capable of infiltrating the micropores of said polymeric sheet; stretching said coated polymeric sheet, after said coating step, in a second direction so as to render said polymeric sheet more microporous, said stretching of said polymeric sheet in the second direction serving to enhance infiltration of said liquid filler material into the micropores of said polymeric sheet; and converting said liquid filler material from a liquid state to a relatively solid state.