METHOD OF PRODUCING MICROPOROUS THERMOPLASTIC RESIN MEMBRANE

摘要

A method of producing a microporous thermoplastic resin membrane of excellent permeability having uniform and fine micropores without filling stress concentrators to the thermoplastic resin is provided. Namely, there is provided a method of producing a microporous thermoplastic resin membrane, in which a thermoplastic resin foam incorporating fine cells having a ratio B/A between a cell size (A) and a wall thickness (B) of the cells of less than 0.5 and having a void ratio of not less than 50 % is subjected to plastic deformation for the boundaries of the cells themselves to such as extent exceeding the shape deformation of the cells, thereby breaking the boundaries of the cells. Also there is provided a microporous thermoplastic resin membrane of excellent permeability having uniform and fine micropores produced by the method as described above.