Polyvinylidene fluoride porous membrane and a method for producing the same
First Claim
1. A porous membrane comprising a polyvinylidene fluoride, resin and having pores running throughout an interior of said porous membrane and opening at both surfaces of said porous membrane,said interior of said porous membrane containing substantially no macrovoids having a diameter of 10 μ
- m or more,the average diameter of said pores in each surface of said porous membrane being within the range of from 0.05 μ
m to less than 5 μ
m,the ratio of the average pore diameter of said pores at each surface of said porous membrane to the average pore diameter of said pores in the interior of said porous membrane in terms of the average pore diameter of pores in a cross-section of said porous membrane taken along a line perpendicular to each surface of said porous membrane, being from 0.5 to 2.0,the ratio of the maximum pore diameter of said pores as measured by the bubble point method to a true average pore diameter of said pores as measured by the half-dry method being from 1.2 to 2.5,and said membrane having a uniform, three-dimensional, network pore structure, and a tensile strength at break of from 70 to 200 kg/cm2, a tensile elongation at break of from 100 to 500% and a porosity of from 40 to 90%.
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Abstract
A porous membrane comprising a polyvinylidene fluoride resin and having a uniform, three-dimensional, network pore structure. The membrane has excellent chemical resistance, excellent filtering characteristics and excellent mechanical properties. The porous membrane can be produced by blending a polyvinylidene fluoride resin, an organic liquid and a powdery hydrophobic silica, subjecting the resultant blend to melt-molding to form a membrane, and extracting the organic liquid and the hydrophobic silica from the melt-molded membrane.
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Citations
12 Claims
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1. A porous membrane comprising a polyvinylidene fluoride, resin and having pores running throughout an interior of said porous membrane and opening at both surfaces of said porous membrane,
said interior of said porous membrane containing substantially no macrovoids having a diameter of 10 μ - m or more,
the average diameter of said pores in each surface of said porous membrane being within the range of from 0.05 μ
m to less than 5 μ
m,the ratio of the average pore diameter of said pores at each surface of said porous membrane to the average pore diameter of said pores in the interior of said porous membrane in terms of the average pore diameter of pores in a cross-section of said porous membrane taken along a line perpendicular to each surface of said porous membrane, being from 0.5 to 2.0, the ratio of the maximum pore diameter of said pores as measured by the bubble point method to a true average pore diameter of said pores as measured by the half-dry method being from 1.2 to 2.5, and said membrane having a uniform, three-dimensional, network pore structure, and a tensile strength at break of from 70 to 200 kg/cm2, a tensile elongation at break of from 100 to 500% and a porosity of from 40 to 90%. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- m or more,
Specification