Microporous film and process for production thereof
Patent 4791144 Issued on December 13, 1988. Estimated Expiration Date: June 12, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
521/90, Ingredient is a heterocyclic compound210/500.36, Alkene other than vinyl264/288.8, Nonuniform product (e.g., porous, etc.) or with tensioning before application of heat264/289.6, With shrinking or with liquid contact during or after stretching264/41, PORE FORMING IN SITU (E.G., FOAMING, ETC.)264/49, By treating occluded solids429/254, Rubber or thermoplastic resin521/134, Cellular product derived from two or more solid polymers or from at least one solid polymer and at least one polymer-forming system521/143, From acyclic mono-unsaturated hydrocarbon as only reactant521/91Ingredient contains a silicon atom
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 (η) of 1.9 to 3.0 dl/g, especially 2.0 to 3.0 dl/g, as measured at 135° C. in tetralin, said microporous film having a network structure comprising intercommunicating pores having a maximum pore size smaller than 1μ and an average pore size of 0.005 to 0.6μ and having a porosity of 30 to 90%, an air permeability of 5 to 500 sec/100 cc and a thickness of 5 to 200μ, said microporous film being molecularly oriented by stretching.
June 12, 2007. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
