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Method for producing porous film

A manufacturing method and porous film technology, applied in the direction of electrical components, circuits, battery pack components, etc., can solve the problems of reduced porosity, reduced solvent evaporation rate, and insufficient increase in porosity, achieving high porosity and inhibiting Effect of shrinkage and shortening of drying time

Inactive Publication Date: 2009-04-22
NITTO DENKO CORP
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0008] However, in this method, even if a solvent with a low boiling point is used for washing, it takes a certain amount of time to dry after washing, so shrinkage of the film occurs, and it is found that the porosity is not sufficiently improved.
In addition, especially if it is intended to be used in a continuous process, since the concentration of impurities (membrane forming solvent or non-aqueous solvent) gradually increases by immersion and washing, the evaporation rate of the solvent during drying decreases, and the porosity also decreases. become significant
In order to prevent this problem, it is necessary to use a cleaning solvent with few impurities, and there are problems that the consumption of cleaning solvent increases, or the purity must be improved when recycling.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0079] The sheet-shaped resin containing the solvent was cut out, fixed in a frame made of SUS, and washed in decane for 3 minutes. The same washing process was repeated twice more. Then, the frame-fixed sheet was stood upright in the vapor of pentafluorobutane (boiling point 40°C) adjusted to 40°C, and kept for 10 minutes, and the vaporized solvent was condensed and flowed down on the membrane surface to perform washing by replacement. net. Then, drying was performed at room temperature (23° C.) and a wind speed of 0.6 m / sec. Then, for heat setting, heat treatment was performed in air at 85° C.×12 h+116° C.×2 h in a state fixed to a metal frame to obtain a porous membrane.

Embodiment 2

[0081] In Example 1, instead of using pentafluorobutane, a mixed solvent of pentafluorobutane (boiling point 40°C) / decane (boiling point 174°C)=90 / 10 (weight ratio) adjusted to 40°C was used, The porous film was washed, dried, and heat-set under the same conditions as in Example 1.

Embodiment 3

[0083] In Example 1, instead of using pentafluorobutane, a mixed solvent of pentafluorobutane (boiling point 40°C) / decane (boiling point 174°C)=80 / 20 (weight ratio) adjusted to 40°C was used, The porous film was washed, dried, and heat-set under the same conditions as in Example 1.

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PUM

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Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a porous membrane by which shrinkage of the porous membrane can be suppressed and the porous membrane having a high porosity can stably be obtained because the drying time of a washing solvent can be shortened even when the purity of the washing solvent is low and to provide a method for producing a separator for batteries.SOLUTION: The method for producing the porous membrane comprises a step of removing low-molecular substances from the porous membrane containing the low-molecular substances with the washing solvent after forming the membrane. The method for producing the porous membrane comprises a step of removing the low-molecular substances from the porous membrane with the liquid washing solvent, a step of bringing the porous membrane into contact with a vapor of the same or another washing solvent and condensing the washing solvent and a step of drying the condensed washing solvent from the porous membrane.

Description

technical field [0001] The present invention relates to a manufacturing method of a porous membrane and a manufacturing method of a battery separator, wherein the manufacturing method of the porous membrane includes: after the membrane is formed, the porous membrane containing a low-molecular-weight substance such as a solvent is removed from the porous membrane using a cleaning solvent. A process for removing low molecular weight substances. Background technique [0002] Porous films made of polyolefin resins are used in the fields of battery separators, electrolytic capacitor diaphragms, moisture-permeable waterproof materials, and various filters. Among them, separators for batteries are attracting attention as important parts of lithium secondary batteries capable of obtaining light weight, high electromotive force, high energy and low self-discharge, and are also expected to be components of batteries for electric vehicles in the future. . [0003] Such a battery sepa...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01M2/14C08J9/00
CPCY02E60/12Y02E60/10
Inventor 水谷薰金田充宏山本孝幸
Owner NITTO DENKO CORP