Microporous film and process for production thereof
AssigneeTokuyama Soda Kabushiki Kaisha
InventorsSatoshi Nagou, Shunichi Nakamura
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Abstract
Disclosed is a microporous polyproplene film comprising a propylene homopolymer, a copolymer of propylene with other copolymerizable monomer or a blend thereof, which has an intrinsic viscosity (.eta.) of 1.9 to 3.0 dl/g, especially 2.0 to 3.0 dl/g, as measured at 135.degree. C. in tetralin, said microporous film having a network structure comprising intercommunicating pores having a maximum pore size smaller than 1.mu. and an average pore size of 0.005 to 0.6.mu. and having a porosity of 30 to 90%, an air permeability of 5 to 500 sec/100 cc and a thickness of 5 to 200.mu., said microporous film being molecularly oriented by stretching.
Claims30
A microporous polypropylene film comprising a propylene homopolymer, a copolymer of propylene with other copolymerizable monomer or a blend thereof, which has an intrinsic viscosity (.eta.) of 1.9 to 3.0 dl/g as measured at 135.degree. C. in tetralin, said microporous film having a network structure comprising intercommunicating pores having a maximum pore size smaller than 1.mu. and an average pore size of 0.005 to 0.6.mu. and having a porosity of 30 to 90%, an air permeability of 5 to 500 sec/100 cc and a thickness of 5 to 200.mu., said microporous film being molecularly oriented by stretching.
A process for the preparation of a microporous polypropylene film, which comprises melt-forming into a sheet or film a mixture comprising (a) 20 to 80% by weight of a propylene homopolymer, a copolymer of propylene with other copolymerizable monomer or a blend thereof, which has an intrinsic viscosity (.eta.) of 1.9 to 3.0 as measured at 135.degree. C. in tetralin, (b) 80 to 20% by weight of at least one siliceous filler selected from the group consisting of silica, silicates and inorganic composites thereof, said siliceous filler having an average particle size smaller than 1.mu., (c) a polyester type plasticizer and/or an epoxy type plasticizer in an amount of 40 to 10% by weight based on the sum of the components (a) and (b), and (d) a silane type dispersant in an amount of 0.01 to 5% by weight based on the sum of the components (a), (b) and (c), and stretching the sheet or film at an area stretching ratio of 1.5 to 30.
A process for the preparation of a microporous polypropylene film, which comprises melt-forming into a sheet or film a mixture comprising (a) 30 to 70% by weight of a propylene homopolymer, a copolymer of propylene with other copolymerizable monomer or a blend thereof, which has an intrinsic viscosity (.eta.) of 1.9 to 3.0 as measured at 135.degree. C. in tetralin, (b') 70 to 30% by weight of at least one nonsiliceous filler selected from the group consisting of oxides, hydroxides, carbonates and sulfates of metals of groups IIA, IIIA and IVB of the Periodic Table, said nonsiliceous filler having an average particle size smaller than 1.mu., (c) a polyester type plasticizer and/or an epoxy type plasticizer in an amount of 0.1 to 5% by weight based on the sum of the components (a) and (b'), (e) a liquid or waxy hydrocarbon polymer in an amount of 0 to 10% by weight based on the sum of the components (a) and (b'), and (f) a fluorine type surface active agent in an amount of 0.01 to 5% by weight based on the sum of the components (a) and (b') and stretching the sheet or film at an area stretching ratio of 1.5 to 30.
Dependencies are inferred from the claim text.