| 摘要 |
This improved porous polypropylene membrane comprises an inner surface, an outer surface and the part between them ( the inter surface region). A solid phase of granular polypropylene forms the inner surface as a densely molten continuous phase with parts having exposed granules. The inter surface region and the outer surface are both formed from a solid phase of polypropylene grains aligned along the axial direction. A three dimensional network of through pores is formed in these solid phases. The index of double refraction, the void ratio, the oxygen gas flux, water permeability and the bubble point of the membrane are 0.001-0.01, 10-60%, 100-1500 l/min m2 atom, at least 100 ml/min mmHg m2 and up to 2.0 kg f/cm2, respectively. The inner -diameter and thickness of the membrane are 150-300 micro-m and 10-150 micro-m respectively. The mean particle size and the mean diameter of pores at the inner surface are 0.1-2.0 micron and 0.1-1.0 micron, respectively. The membrane is obtd. by melt-kneading a compsn. composed of polypropylene, an organic filler such as paraffin and a nucleating agent, then ejecting it into a gas atmosphere through a nozzle or a slit shaped in the form of a cylindrical or flat membrane. The membrane is then brought into contact with a cooling and solidifying fluid composed of silicone oil or polyether, and then treated with an extractant. The organic filler must be extractable with an extractant. |
