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AssigneeDaicel Chemical Industries, Ltd.
InventorsToyozo Hamada, Shuji Nakatsuka, Kiyoharu Mizumoto
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Porous membranes having a micro phase separation structure and showing a light transmittance at the wavelength of 400 nm of not less than 30% are obtained by the dry phase conversion method comprising drying a coating layer of a dope containing a polymer, a good solvent for the polymer and a poor solvent for the polymer which solvent has a higher boiling point than the good solvent. The polymer includes cellulose derivatives, vinyl-series polymers such as acrylonitrile-series polymers and (meth)acrylic acid ester-series polymers, polysulfone-series polymers, and the like. The porous polymer membranes have a porosity of 10 to 60%, a mean pore size of about 0.002 to 0.35 μm and a maximum pore size of not greater than 0.4 μm. These porous membranes shows not only excellent transparency but also high productivity.
A porous membrane comprising at least one polymer selected from the group consisting of cellulose derivatives, vinyl-series polymers and polysulfone-series polymers, and showing a light transmittance of not less than 30% at the wavelength of 400 nm.
A porous membrane (A) comprising at least one polymer selected from the group consisting of cellulose derivatives, vinyl-series polymers and polysulfone-series polymers, (B1) having a porosity of 10 to 60% or (B2) having pores with a mean pore size of 0.002 to 0.35 μm and a maximum pore size of not larger than 0.4 μm, and (C) showing a light transmittance of not less than 30% at the wavelength of 400 nm.
A laminate film which comprises a substrate and a porous layer formed on at least one side of said substrate, said porous layer comprising at least one polymer selected from the group consisting of cellulose derivatives, vinyl-series polymers and polysulfone-series polymers and having a light transmittance of not less than 30% at the wavelength of 400 nm.
A laminate film which comprises a plurality of substrates and a porous layer interposed or sandwiched between said substrates, said porous layer comprising at least one polymer selected from the group consisting of cellulose derivatives, vinyl-series polymers and polysulfone-series polymers and having a light transmittance of not less than 30% at the wavelength of 400 nm.
A recording sheet which comprises a substrate, an ink-absorbing layer formed on at least one side of said substrate, and a porous polymer layer having a micro phase separation structure formed on said ink-absorbing layer, wherein said porous polymer layer comprises at least one polymer selected from the group consisting of cellulose derivatives, vinyl-series polymers and polysulfone-series polymers.
A porous membrane produced by a process comprising drying a coating layer or film of a dope comprising at least one polymer selected from the group consisting of cellulose derivatives, vinyl-series polymers and polysulfone-series polymers, a good solvent for the polymer and a poor solvent for the polymer, wherein the poor solvent having a higher boiling point than the good solvent and the proportion of the poor solvent is 1 to 50 parts by weight per 100 parts by weight of the good solvent, and which shows a light transmittance of not less than 30% at the wavelength of 400 nm and has a micro phase separation structure and a mean pore size of 0.002 to 0.35 μm with the maximum pore size of not larger than 0.4 μm.
Dependencies are inferred from the claim text.