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Porous polyolefin film

A polyolefin membrane and porosity technology, applied in the field of polyolefin microporous membranes, can solve the problems of pore blockage, porosity reduction, melting point rise, etc., and achieve the effect of improving shutdown characteristics and excellent foreign body resistance.

Active Publication Date: 2020-09-18
TORAY IND INC
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the melting point rises in any case, so good shutdown characteristics cannot be obtained
In addition, although good shutdown performance is obtained by lowering the melting point of the raw material, the pores are closed during heat treatment, so the porosity decreases

Method used

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  • Porous polyolefin film
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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0169] As a raw material, a Mw of 0.30×10 6, MwD (Mw / Mn) is 18, MFR is 2.0 g / 10min, the ethylene / 1-hexene copolymer (PE (3) described in Table 1) that has melting point of 134 degreeC. Add 70% by mass of liquid paraffin to 30% by mass of the polyethylene composition, further, add 0.5% by mass of 2,6-di-tert-butyl-p-cresol and 0.7% by mass based on the mass of polyethylene in the mixture % tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)-propionate]methane was mixed as an antioxidant to prepare a polyethylene resin solution.

[0170] The obtained polyethylene resin solution was put into a twin-screw extruder, kneaded at 180° C., supplied to a T-die, and extruded into a sheet so that the final microporous film thickness became 20 μm, and then extruded into a sheet. The output was cooled with a cooling roll controlled at 25° C. to form a gel-like sheet.

[0171] The gel-like sheet obtained is passed through a tenter stretching machine at 115° C. along the length directi...

Embodiment 2～6

[0176] A polyolefin microporous membrane was produced in the same manner as in Example 1, except that the raw material described in the raw material characteristics (Table 1) of the polyolefin microporous membrane was changed as shown in Table 2. Table 2 shows the evaluation results of the obtained polyolefin microporous membrane.

Embodiment 5

[0188] In Example 5, since the molecular weight of the raw material was increased compared with Example 1, it is considered that although it has high toughness, the density of linking molecules is increased, the movement of crystals is suppressed, and as a result, the shutdown temperature is increased. However, since a raw material lower than the melting point of the raw material used in Example 1, such as 133° C., was used in addition to the entanglement control of the amorphous portion using the ethylene / 1-hexene copolymer, a low shutdown temperature was maintained. , has good porosity and needle penetration test and foreign body resistance.

[0189] In Comparative Example 1, a good porosity was obtained by using a raw material with a high melting point, but the use of relatively small molecular weight HDPE was stretched at a high ratio, so it was highly oriented, and as a result, the elongation decreased due to high strength. to good toughness. In addition, as a result of ...

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Abstract

This porous polyolefin film: has a shutdown temperature of 133 DEG C or lower; a porosity of 41% or higher; a value of 12,500 or higher for (longitudinal (MD) direction tensile elongation (%) * longitudinal (MD) direction tensile strength (MPa) + width (TD) direction tensile elongation (%) * width (TD) direction tensile strength (MPa)) / 2; and satisfies formula (1),where TSD (DEG C) is the shutdowntemperature and Tm (DEG C) is the lowest melting point of the melting points of respective layers. Formula (1) is Tm-TSD >= 0. Provided is a porous polyolefin film that offers excellent safety against internal short-circuit, thermal runaway, or the like without lowering the permeability of conventional microporous membranes.

Description

technical field [0001] The present invention relates to a microporous membrane widely used as a separation membrane for separation of substances, selective permeation, etc., and as a separator of electrochemical reaction devices such as alkaline, lithium secondary batteries, fuel cells, and capacitors. In particular, it relates to the provision of a polyolefin microporous membrane suitable for use as a separator for lithium ion batteries, and the microporous membrane does not reduce the permeability compared with conventional microporous membranes, and is suitable for internal short circuit and needle penetration tests of batteries. Excellent safety. Background technique [0002] Polyolefin microporous membranes are used as filters, separators for fuel cells, separators for capacitors, and the like. It is particularly suitable as a separator for lithium ion batteries widely used in notebook personal computers, mobile phones, digital cameras, and the like. The reason for th...

Claims

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Application Information

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IPC IPC(8): C08J9/26H01G9/02H01G11/52H01M2/16H01M50/417H01M50/489H01M50/491
CPCH01G11/52H01G9/02Y02E60/10C08J9/286C08J2205/044C08J2323/08H01M50/403H01M50/417H01M50/457H01M50/494H01M10/0525H01M10/4235Y02T10/70H01M50/491H01M50/489C08J9/26C08J5/18B29C48/0018B29C48/022B29C48/08B29K2023/065B29K2105/04C08J2323/20
Inventor 丰田直树下川床辽石原毅久万琢也
Owner TORAY IND INC
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