Multi-layer microporous membrane and preparation method thereof

A technology of microporous film and surface layer, applied in the field of microporous film, can solve the problems of uneven quality, deterioration of melt mixing ability, deterioration of physical properties, etc.

Active Publication Date: 2018-07-10
SHENZHEN SENIOR TECH MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

However, this method tends to cause problems such as deterioration of melt-mixing ability due to addition of inorganic materials, generation of pinholes and non-uniform quality due to deterioration of melt-mixing ability at the time of stretching, and possible problems due to the interaction of inorganic ma...

Method used

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  • Multi-layer microporous membrane and preparation method thereof

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preparation example Construction

[0018] The embodiment of the present invention discloses a method for preparing a multilayer microporous membrane, which includes the following steps: melting and mixing 50wt% to 90wt% of the first high boiling point diluent and 10wt% to 50wt% of the first polymer resin to form the first The mixture, the first polymer resin contains more than 90wt% of polyethylene resin; 50wt% to 90wt% of the second high-boiling point diluent and 10wt% to 50wt% of the second polymer resin are melted and mixed to form the second mixture. The second polymer resin contains 5wt% to 15wt% of polyvinylidene fluoride resin (PVDF) and 85wt% to 95wt% of polyethylene resin; the first mixture and the second mixture are melted and mixed through an extruder to form A slab having a three-layer structure with the melt of the first mixture as the middle layer and the melt of the second mixture as the skin layer; stretching the slab into a film from which the diluent is washed , After heat setting, a multi-lay...

Embodiment 1

[0039] a. Blend 30% by weight of polyethylene resin and 70% by weight of paraffin oil, add to a twin-screw extruder, extrude at 210°C, and plasticize evenly.

[0040] b. Adding 10% by weight of PVDF and 90% by weight of polyethylene resin into a mixer for pre-blending. 30% by weight of the above mixture and 70% by weight of paraffin oil were blended, added to a twin-screw extruder, extruded at 210° C., and plasticized uniformly.

[0041] c. The melt formed by the twin-screw extruder passes through the die head and the quenching roll to form a thick sheet. The temperature of the quenching roll is 35 ° C. The thick sheet is stretched 5X7 times in the longitudinal and transverse directions, and extracted in methylene chloride solution for 2 minutes. 1. Heat setting at 125°C for 5 minutes to prepare a three-layer polyolefin microporous membrane. The performance test results are shown in Table 1.

Embodiment 2

[0043] a. Blend 30% by weight of polyethylene resin and 70% by weight of paraffin oil, add to a twin-screw extruder, extrude at 210°C, and plasticize evenly.

[0044] b. Adding 5% by weight of PVDF and 95% by weight of polyethylene resin into a mixer for pre-blending. 30% by weight of the above mixture and 70% by weight of paraffin oil were blended, added to a twin-screw extruder, extruded at 210° C., and plasticized uniformly.

[0045] c. The melt formed by the twin-screw extruder passes through the die head and the quenching roll to form a thick sheet. The temperature of the quenching roll is 35 ° C. The thick sheet is stretched 5X7 times in the longitudinal and transverse directions, and extracted in methylene chloride solution for 2 minutes. 1. Heat setting at 125° C. for 5 minutes to prepare a three-layer polyolefin microporous membrane. The performance test results are shown in Table 1.

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Abstract

The invention provides a preparation method thereof of multi-layer microporous membrane. The preparation method includes melting and mixing a first high-boiling-point diluent and first polymer resin to form a first mixture; melting and mixing a second high-boiling-point diluent and second polymer resin to form a second mixture; melting and mixing the first mixture and the second mixture through anextruder to form a thick sheet with three-layer structure; drawing the thick sheet into membrane, washing out the diluents from the membrane, and carrying out thermoforming to obtain the multi-layermicroporous membrane; wherein the first polymer resin comprises 90 wt% or above polyethylene resin, the second polymer resin comprises 5 wt%-15 wt% of polyvinylidene fluoride resin and 85 wt%-95 wt% of polyethylene resin, melt of the first mixture serves as an intermediate layer, and melt of the second mixture serves as a surface layer. Compared with the prior art, the multi-layer microporous membrane has excellent heat resistance, high-imbibition retainability and good low-temperature cell closing property.

Description

technical field [0001] The invention relates to the technical field of microporous membranes, in particular to a multilayer microporous membrane and a preparation method thereof. Background technique [0002] At present, polyolefin microporous membranes are widely used in the manufacture of various separation membranes, capacitor diaphragms and lithium-ion battery diaphragms. Among the existing disclosed technical methods, there are mainly two methods for producing polyolefin microporous membranes: melt extrusion stretching method (MECUS) and thermally induced phase separation method (TIPS). The thermally induced phase separation method, commonly known as the wet method, is a method that melts and mixes polyolefins and high-boiling point pore-forming agents in a high-temperature environment to form a homogeneous system. During the cooling process, the system undergoes phase separation, and finally uses the corresponding volatile solvent The pore-forming agent is washed away...

Claims

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Application Information

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IPC IPC(8): B32B27/08B32B27/30B32B27/32H01M2/14H01M2/16B29C47/06B29L7/00H01M50/403H01M50/411H01M50/417H01M50/489H01M50/491
CPCB29C48/08B29C48/21B32B27/08B32B27/304B32B27/32B29L2007/00B32B2307/306H01M50/403H01M50/411H01M50/449Y02E60/10
Inventor 蔡启肖武华陈勇陈良
Owner SHENZHEN SENIOR TECH MATERIAL
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