초록 ▼

A process for producing an air-permeable film, which comprises: (a) biaxially stretching a tubular unstretched film of a composition comprising 42 to 87 vol % of a thermoplastic resin and 58 to 13 vol % of an inorganic filler along a truncated-conical mandrel; (b) blowing a gas over the outside of t

A process for producing an air-permeable film, which comprises: (a) biaxially stretching a tubular unstretched film of a composition comprising 42 to 87 vol % of a thermoplastic resin and 58 to 13 vol % of an inorganic filler along a truncated-conical mandrel; (b) blowing a gas over the outside of the biaxially stretched tubular film to cool said film; and (c) simultaneously blowing a gas continuously into the tube of the film so as to penetrate the gas through the film and go outside.

대표청구항 ▼

A process for producing an air-permeable film, which comprises: (a) biaxially stretching a tubular unstretched film of a composition comprising 42 to 87 vol % of a thermoplastic resin and 58 to 13 vol % of an inorganic filler along a truncated-conical mandrel; (b) blowing a gas over the outside of t

A process for producing an air-permeable film, which comprises: (a) biaxially stretching a tubular unstretched film of a composition comprising 42 to 87 vol % of a thermoplastic resin and 58 to 13 vol % of an inorganic filler along a truncated-conical mandrel; (b) blowing a gas over the outside of the biaxially stretched tubular film to cool said film; and (c) simultaneously and, continuously blowing a gas under controlled pressure into the tube of the film such that the gas penetrates through the film around its entire circumference to the exterior of the film.