The Japan Steel Works, Ltd.

Ryou Ishiguro

Satoru Nakamura

Mariko Yoshioka

Yoshiyuki Kushizaki

A method for producing a cellulose nanofiber-containing polyolefin microporous stretched film according to the invention includes: a first step of obtaining a cellulose powder dispersion mixture by uniformly dispersing a cellulose which has a powder particle shape and whose hydroxyl groups have been subjected to a lipophilizing treatment using a dibasic acid anhydride, in a plasticizer; a second step of melt-kneading the cellulose powder dispersion mixture and a polyolefin to obtain a polyolefin resin composition; a third step of extrusion-molding the polyolefin resin composition to obtain an extrudate; a fourth step of stretching the extrudate with a film stretcher to obtain a film; a fifth step of extracting out the plasticizer from the film; and a sixth step of thermally fixing the film from which the plasticizer has been extracted out for inhibiting contraction, while stretching the film at a temperature not higher than a melting point of the polyolefin, in which a twin-screw kneading extruder is used only once throughout the second and third steps.

Process for producing cellulose-nanofiber-filled microporous stretched polyolefin film, microporous cellulose-nanofiber composite film, and separator for non-aqueous secondary battery

The present invention provides a method for producing a microporous film, including: preparing a resin composition containing polypropylene (PP) as a resin component and containing from 0.01 to 20 parts by weight of a chemically modified cellulose or chemically modified cellulose nanofiber per 100 parts by weight of the resin component and from 0.01 to 3 parts by weight of a &#x3b2;-crystal nucleating agent per 100 parts by weight of the resin component; melt-molding the resin composition into a film-like material in which the crystal phase of a polypropylene component in the resin composition is substantially a &#x3b2;-crystal phase, and subsequently stretching the film-like material at a temperature of 60 to 160&#xb0; C., and provides a microporous film.

Method for manufacturing microporous film and microporous film

The present invention provides a production method and the like of a microporous stretched film having a high puncture strength and the like. The method includes: a first step of melt-kneading a cellulose nanofiber and a polyolefin resin to thereby disperse the nanofiber in the resin; a second step of removing water from a kneaded mixture obtained in the first step; a third step of mixing a plasticizer in the nanofiber and the resin and melt-kneading them to prepare a polyolefin resin composition; a fourth step of extrusion-molding the polyolefin resin composition; a fifth step of stretching an extrusion-molded article obtained in the fourth step to form a film; and a sixth step of extracting the plasticizer from the film.

Microporous stretched cellulose nanofiber-containing polyolefin film, method for producing microporous stretched cellulose nanofiber-containing polyolefin film, and separator for nonaqueous secondary batteries

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Hiroshima, Japan

Ryou Ishiguro