New Japan Chemical Co., Ltd.

Kiyoshi Sadamitsu

Toshiaki Kobayashi

Naoki Ikeda

Manabu Hoki

Kenichiro Nagata

Koichi Ogino

Hiroshi Kitagawa

Yasuyuki Kawahara

Masahide Ishikawa

Masafumi Yoshimura

Kazuaki Mizoguchi

Yuji Kawashima

Disclosed is a successively biaxially stretched film obtained by successive biaxial stretching method comprising extruding a melt of a &#x3b2;-crystal nucleating agent-containing polypropylene-based resin composition from a T-die, cooling the extruded resin on a chill roll, and stretching the resulting web sheet longitudinally and then transversely, wherein the longitudinally stretched sheet is made to have a degree of &#x3b2;-crystal orientation of less than 0.3 by the following method (I) and/or (II), optionally subjected to annealing treatment, and transversely stretched: method (I): melting the polypropylene-based resin composition containing needle crystals of a specific &#x3b2;-crystal nucleating agent at a temperature not lower than m.p. of the polypropylene-based resin and lower than dissolution temperature of the &#x3b2;-crystal nucleating agent in the polypropylene-based resin melt, and extruding the melt from the T-die at the same temperature, method (II): adjusting neck-in ratio during longitudinal stretching to 25 to 55%. The porous polypropylene film has good breakage resistance during manufacture, excellent thickness uniformity, high porosity and air-permeability, and is useful for battery separators.

Successively biaxial-oriented porous polypropylene film and process for production thereof

Disclosed is a successively biaxially stretched film obtained by successive biaxial stretching method comprising extruding a melt of a &#x3b2;-crystal nucleating agent-containing polypropylene-based resin composition from a T-die, cooling the extruded resin on a chill roll, and stretching the resulting web sheet longitudinally and then transversely, wherein the longitudinally stretched sheet is made to have a degree of &#x3b2;-crystal orientation of less than 0.3 by the following method (I) and/or (II), optionally subjected to annealing treatment, and transversely stretched: The porous polypropylene film has good breakage resistance during manufacture, excellent thickness uniformity, high porosity and air-permeability, and is useful for battery separators.

Disclosed is a porous film made of a resin composition containing (I) (i) a propylene-ethylene copolymer or (ii) a polypropylene-based resin mixture containing a propylene-ethylene copolymer, each having an ethylene content of 3.0 to 7.0 wt. % and an MFR measured at 230&#xb0; C. of 2.0 to 4.0 g/10 min and (II) a &#x3b2;-crystal nucleating agent; the film having a porosity of 20 to 80%, a Gurley air permeability of 5,000 sec/100 cc or lower as measured according to JIS P-8117, a water vapor permeability of 2,000 g/m&#xb7;24 h or higher as measured according to JIS Z-0208 and a water pressure resistance of 75 kPa or higher as measured according to JIS L-1092 using an aqueous surfactant solution; a process for producing the same; and an absorbent article employing the porous film as a backsheet.

Porous polypropylene film, process for producing the same, and absorbent article employing the film

The present invention provides a method of molding a polyolefin-based resin comprising the steps of dissolving at least one dibenzylidene sorbitol compound in a molten polyolefin resin, cooling the molten resin to a temperature not higher than the sol-gel transition temperature during the cooling cycle to form network-like crystals of the dibenzylidene sorbitol compound, and molding the resulting resin composition at a temperature not lower than the melting temperature of the polyolefin-based resin but not higher than the sol-gel transition temperature during the heating cycle; and a polyolefin resin molded article obtainable by this molding method.

Orientated gel molding method of polyolefin-based resin composition and molded article obtainable by the method

The present invention provides method of molding a polyolefin-based resin comprising the steps of dissolving at least one dibenzylidene sorbitol compound in a molten polyolefin resin, cooling the molten resin to a temperature not higher than the sol-gel transition temperature during the cooling cycle to form network-like crystals of the dibenzylidene sorbitol compound, and molding the resulting resin composition at a temperature not lower than the melting temperature of the polyolefin-based resin but not higher than the sol-gel transition temperature during the heating cycle; and a polyolefin resin molded article obtainable by this molding method.

Orientated gel molding method of polyolefin based resin composition

Disclosed are a crystalline polypropylene resin composition comprising a crystalline polyproplylene resin and a &bgr;-nucleating agent, and a method of increasing the proportion of &bgr;-form crystals in a crystalline polypropylene resin molding comprising molding the composition, the &bgr;-nucleating agent being a diamide compound.

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Yawata, Japan

Kiyoshi Sadamitsu