초록 ▼

A heterogeneous membrane of a thermoplastic crystalline polymer composed of a microporous layer and a nonporous layer and having excellent properties, for example as a diaphragm for separating a gaseous mixture; and a process for production thereof. The heterogeneous membrane is in the form of, for

A heterogeneous membrane of a thermoplastic crystalline polymer composed of a microporous layer and a nonporous layer and having excellent properties, for example as a diaphragm for separating a gaseous mixture; and a process for production thereof. The heterogeneous membrane is in the form of, for example, a flat film or a tubular film (preferably a hollow fiber). The microporous layer contains pores with a diameter of 0.01 to 50 microns, whereas the nonporous layer does not substantially contain pores having a diameter of at least 30 Åand has a thickness of 0.01 to 1 micron. The heterogeneous membrane is characterized by having at least 3 times as high an apparent oxygen permeability coefficient P(O2) at 25°C. as a nonporous homogeneous membrane of the same material and an oxygen-nitrogen separation coefficient a2/N2) at 25°C., i.e. the ratio of the apparent oxygen permeability coefficient P(O2) to the apparent nitrogen permeability coefficient P(N2), of at least 1.2. The heterogeneous membrane can be industrially produced easily and conveniently with a high efficiency by a melt-extrusion film-forming step, a stretching step and a heat-setting step under specified conditions.

대표청구항 ▼

A heterogeneous membrane in the form of a flat film, a tubular film or a hollow fiber, said membrane having a microporous layer and a nonporous layer and being formed by melt-extrusion from a thermoplastic crystalline polymer and subsequent stretchings including amorphous stretching; said microporou

A heterogeneous membrane in the form of a flat film, a tubular film or a hollow fiber, said membrane having a microporous layer and a nonporous layer and being formed by melt-extrusion from a thermoplastic crystalline polymer and subsequent stretchings including amorphous stretching; said microporous layer containing pores with a diameter of 0.01 to 50 microns, said nonporous layer containing substantially no pore with a diameter of at least 30 Åand having a thickness of 0.01 to 1 micron, said membrane having at least 3 times as high an apparent oxygen permeability coefficient P(O2) at 25°C. as a nonporous homogeneous membrane of the same material, and said membrane having an oxygen/nitrogen separation coefficient a2/N2) at 25°C., which is the ratio of the apparent oxygen permeability coefficient P(O2) to the apparent nitrogen permeability coefficient P(N2), of at least 1.2.