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AssigneeKuraray Co., Ltd.
InventorsArata Ishiodori, Kensaku Komatsu, Koji Yamada
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A porous membrane, made of polyvinylidene fluoride which is excellent in fractionating capability, permeating capability and physical strength and suitable for use in water treatment such as water purification, preparation of drinking water, preparation of water for industrial use and wastewater treatment, and which can be manufactured inexpensively and easily. The porous membrane has one surface formed with round or oval micropores and the opposite surface formed with substantially slit shaped micropores. The round or oval micropores have an average ratio between the major axis and the minor axis, which is within the range of 1:1 to 5:1, and the substantially slit shaped micropores have an average ratio between the major axis and the minor axis, which is not smaller than 5:1 and the particle cutoff of the membrane is not smaller than 0.2 μm.
A porous membrane made of a vinylidene fluoride resin of a particle cutoff not smaller than 0.2 μm, including a first surface and a second surface opposite to each other, the first surface having micropores of a round or oval shape of average ratio, between the major axis and the minor axis, within the range of 1:1 to 5:1 and the second surface having micropores of substantially slit shape of average ratio, between the major axis and the minor axis, not smaller than 5:1, wherein the porous membrane is made of a blended polymer including the vinylidene fluoride resin in a quantity within the range of 90 to 99 wt % and a hydrophilic resin in a quantity within the range of 1 to 10 wt %.
A method of preparing a porous membrane made of a blended polymer including a vinylidene fluoride resin and a hydrophilic resin, which comprises:
Dependencies are inferred from the claim text.