Patent ID: 7488529
Filing Date: 2009-02-10
Classification: A61F,C08J,C08L,Y10T

Abstract:
1. A porous film obtained by melting and kneading a resin composition consisting of a polyolefin resin {component (A)} and a bulking agent {component (B)} as the main components, and a silicone {component (C)} and a castor oil {component (D)}, followed by drawing, which shrinks by from 40 to 95% in one direction and expands by from 5 to 40% in a direction transverse thereto, when soaked in a first silicone oil of 200° C. for 60 seconds, wherein the castor oil and the silicone are present in a weight ratio of from 0.5 to 1.0 and the castor oil and the silicone are uniformly dispersed within the polyolefin, wherein the drawing is a uniaxial drawing in only one direction to a total draw ratio of from 1.2 to 5.0 at a temperature of from 23° C. to the softening temperature of the resin as measured in accordance with JIS K6760, wherein the silicone is at least one selected from the group consisting of a polysiloxane and a silicone rubber, and wherein the castor oil consists of the hardened castor oil.