Polyvinylidene fluoride hollow fiber microporous membrane and process for production of the same
AssigneeToyo Boseki Kabushiki Kaisha
InventorsAkihiro Ariji, Hideki Yamada
Life of this patent
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Abstract
This disclosure relates to an anisotropic polyvinylidene fluoride hollow fiber microporous membrane containing a polyvinylidene fluoride resin. The hollow fiber microporous membrane does not include macrovoids, and has mainly a net-like structure. In addition, the hollow fiber microporous membrane has a dense outer layer on an outer surface, and a homogeneous bulk layer that is internally adjacent to the outer layer and has a coarser structure than the outer layer. The porosity of the bulk layer is at least 1.5 times the membrane surface porosity of the outer layer. The dense structure of the outer layer changes substantially discontinuously into the coarse structure of the bulk layer.
Claims7
An anisotropic polyvinylidene fluoride hollow fiber microporous membrane comprising a polyvinylidene fluoride resin,
- wherein:
- (1) the hollow fiber microporous membrane does not include macrovoids, and has mainly a net-like structure;
- (2) the hollow fiber microporous membrane has a dense outer layer on an outer surface, and a homogeneous bulk layer that is internally adjacent to the outer layer and that has a coarser structure than the outer layer;
- (3) a porosity A of the bulk layer is at least 1.5 times a membrane surface porosity B of the outer layer;
- (4) the dense structure of the outer layer changes substantially discontinuously into the coarse structure of the bulk layer;
- (5) the membrane surface porosity of the outer layer is not more than 40%, and the porosity of the bulk layer ranges from 20% to 60%;
- and
- (6) a tensile strength at break ranges from 2 MPa to 20 MPa, and a tensile elongation at break ranges from 200% to 500%.
Dependencies are inferred from the claim text.