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

Patent metadata

Field	Value
Publication number	US-2016133902-A1
Application number	US-201414895856-A
Country	US
Kind code	A1
Filing date	Jun 4, 2014
Priority date	Jun 4, 2013
Publication date	May 12, 2016
Grant date	—

Abstract

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.

First claim

1 . A method for producing a cellulose nanofiber-containing polyolefin microporous stretched film, the method comprising: 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,
wherein a twin-screw kneading extruder is used only once throughout the second and third steps.

2 . The method for producing a cellulose nanofiber-containing polyolefin microporous stretched film according to claim 1 , wherein the lipophilizing treatment comprises performing a monoesterification treatment followed by performing a secondary propylene oxide addition treatment.

3 . The method for producing a cellulose nanofiber-containing polyolefin microporous stretched film according to claim 1 , wherein one kind or a mixture of several kinds among: liquid paraffin, nonane, decane, decalin, paraxylene, undecane and dodecane which are linear or cyclic aliphatic hydrocarbons; mineral oil fractions whose boiling point corresponds to that of these compounds; and dibutyl phthalate and dioctyl phthalate which are phthalates having a liquid form at room temperature, is used as the plasticizer.

4 . The method for producing a cellulose nanofiber-containing polyolefin microporous stretched film according to claim 1 , wherein the cellulose powder is contained in an amount of from 0.01 to 30% by weight in the cellulose powder dispersion mixture.

5 . A cellulose nanofiber microporous composite film comprising the cellulose nanofiber-containing polyolefin microporous stretched film produced by the production method according to claim 1 .

6 . A cellulose nanofiber microporous composite film, wherein the cellulose powder in the polyolefin microporous stretched film produced by the production method according to any of claim 1 is contained in an amount of from 0.01 to 30% by weight based on a total weight of the polyolefin microporous stretched film.

7 . A separator for nonaqueous secondary batteries, comprising the cellulose nanofiber-containing polyolefin microporous stretched film produced by the production method according to claim 1 .

Assignees

• Japan Steel Works Ltd

Inventors

• Nakamura Satoru
• Kushizaki Yoshiyuki
• ISHIGURO Ryou
• Yoshioka Mariko

Classifications

• B29D99/005 Primary

  Producing membranes · CPC title

• C08K7/02

  Fibres or whiskers · CPC title

• H01M10/0525

  Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries · CPC title

• C08J2323/02

  not modified by chemical after treatment · CPC title

• C08J5/18

  Manufacture of films or sheets · CPC title