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Method for preparing polyolefin microporous membrane through wet process

A polyolefin microporous membrane and polyolefin technology, applied in the polymer field, can solve the problems of poor pore uniformity of the microporous membrane, poor mechanical properties of the microporous membrane, residual solvent and detergent, etc. Low residue, high strength effect

Active Publication Date: 2010-07-21
德州东鸿制膜科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

In the known technology, the existing polyolefin microporous membrane preparation methods include melt stretching method (commonly known as dry method) and thermal phase separation method (commonly known as wet method). The thermal phase separation method is to dissolve the polymer at high temperature. In a solvent with high boiling point and low volatility, a homogeneous solution is formed, and then the temperature is lowered and cooled. During the cooling process, the system generates dust and separates phases, forming two structures with the polymer as the continuous phase and the solvent as the dispersed phase. Volatile reagents wash away the solvent to obtain a polymer microporous membrane with a certain structural shape. At present, it is mainly used to prepare a single-layer polyethylene battery separator. The mechanical properties of the prepared microporous membrane are poor, especially for membrane formation. A large number of solvents and detergents have serious residual problems, which reduces the air permeability of the membrane and the microporous membrane produced has poor pore uniformity

Method used

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  • Method for preparing polyolefin microporous membrane through wet process

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] a At 250°C, the weight-average molecular weight of 20% of the total polyolefin will be 3.5×10 6 The ultra-high molecular weight polyethylene resin (125Kg) adds in the kneader and kneads, then it is cooled to 180 ℃, adds the weight-average molecular weight that accounts for 80% of polyolefin total amount again and is 3.5 * 10 5 High-density polyethylene (500Kg) and the nucleating agent zinc stearate (ZnSt 2 ) (5Kg), prepare polyolefin mixture;

[0030] b Add the obtained polyolefin mixture and liquid paraffin into a twin-screw extruder at a ratio of 1:4, extrude through a T-shaped die at 215°C, and cool the cooling roll to form a gel sheet, the temperature of the cooling roll is 35°C ;

[0031] c. Simultaneously biaxially stretch the obtained gel-like sheet 5×5 times at 115° C.;

[0032] d Immerse the stretched film in a dichloromethane solution at room temperature and normal pressure, and use ultrasonic extraction, the ultrasonic frequency is 20kHz, and the intensity...

Embodiment 2

[0035] a At 250°C, the weight-average molecular weight of 20% of the total polyolefin will be 3.5×10 6 The ultra-high molecular weight polyethylene resin (125Kg) adds in the kneader and kneads, then it is cooled to 180 ℃, adds the weight-average molecular weight that accounts for 80% of polyolefin total amount again and is 3.5 * 10 5 high-density polyethylene (500Kg) and the nucleating agent zinc stearate (ZnSt 2 ) (7.5Kg), preparing polyolefin mixture;

[0036] b Add the obtained polyolefin mixture and liquid paraffin (2000Kg) into the twin-screw extruder at a ratio of 1:4, extrude through a T-shaped die at 215°C, and cool the cooling roll to form a gel sheet. 35°C;

[0037] c. Simultaneously biaxially stretch the obtained gel-like sheet 5×5 times at 115° C.;

[0038] d Immerse the stretched film in a dichloromethane solution at room temperature and normal pressure, and use ultrasonic extraction, the ultrasonic frequency is 20kHz, and the intensity is 1.5W / cm 2 , the wash...

Embodiment 3

[0041] a At 250°C, the weight-average molecular weight of 20% of the total polyolefin will be 3.5×10 6 The ultra-high molecular weight polyethylene resin (125Kg) adds in the kneader and kneads, then it is cooled to 180 ℃, adds the weight-average molecular weight that accounts for 80% of polyolefin total amount again and is 3.5 * 10 5 High-density polyethylene (500Kg) and the nucleating agent zinc stearate (ZnSt 2 ) (5Kg), prepare polyolefin mixture;

[0042] b Add the obtained polyolefin mixture and liquid paraffin (2000Kg) into the twin-screw extruder at a ratio of 1:4, extrude through a T-shaped die at 215°C, and cool the cooling roll to form a gel sheet. 35°C;

[0043] c. Simultaneously biaxially stretch the obtained gel-like sheet 5×5 times at 115° C.;

[0044] d Immerse the stretched film in a dichloromethane solution at room temperature and normal pressure, and use ultrasonic extraction, the ultrasonic frequency is 50kHz, and the intensity is 1.5W / cm 2 , the washing ti...

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Abstract

The invention discloses a method for preparing polyolefin microporous membrane through wet process, aiming at solving the problems of low mechanical strength and poor uniformity of the clearances of the membrane. The method takes polyolefine resin, nucleating agent and solvent as the materials to prepare polyolefin microporous membrane through polyolefine solution preparation procedure, extrusion and gel sheet forming procedure, drawing procedure, membrane forming and solvent removal procedure, drying procedure and heat treatment stereotyping procedure. The preparation technique is simple and the polyolefin microporous membrane prepared through the method can be used as medical dressing, clothes lining, various separation membranes, water treatment membrane as well as membranes for a super capacitor, a battery and the like.

Description

technical field [0001] The invention belongs to the method for preparing polyolefin microporous membrane by wet method in the technical field of macromolecule. Background technique [0002] Polyolefin microporous membrane is a polymer membrane with a pore diameter between 5nm and 1000nm. Single-layer polyolefin microporous membrane has been widely used in the preparation of capacitor separators, battery separators and various separation membranes. In the known technology, the existing polyolefin microporous membrane preparation methods include melt stretching method (commonly known as dry method) and thermal phase separation method (commonly known as wet method). The thermal phase separation method is to dissolve the polymer at high temperature. In a solvent with high boiling point and low volatility, a homogeneous solution is formed, and then the temperature is lowered and cooled. During the cooling process, the system generates dust and separates phases, forming two struct...

Claims

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Application Information

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IPC IPC(8): C08L23/00C08L23/06C08L23/12C08K5/09C08K5/098C08K3/34B29C55/16B29C71/02B08B3/12
Inventor 谷传明徐长城赵静牛树章
Owner 德州东鸿制膜科技有限公司
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