Method for preparing polyolefin microporous membranes with uniform structures

A technology of polyolefin microporous membrane and polyolefin resin is applied in the field of preparation of polyolefin microporous membrane, and can solve the problems of poor battery performance, waste edge removal, low lithium ion passing ability, etc.

Active Publication Date: 2010-06-09
SHENZHEN SENIOR TECH MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

When used as a separator for lithium-ion batteries, it has poor gas permeability, low lithium-ion penetration ability, and poor battery performance.
In the synchronous stretching process, although the slipping problem of the longitudinal stretching is solved, on the one hand, it is the same as the step stretching, and the waste edge needs to be cut off, and the product yield is low; on the other hand, the investment in the equipment is relatively large

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0029] 10% (weight) of high-density polyethylene (melting point 133° C.) is dropped into a twin-screw extruder (78 mm in diameter, L / D=50, strong mixing type), and 90 % (weight) of liquid paraffin (kinematic viscosity 90cst / 40°C), melted and kneaded under the conditions of 200°C and 150 rpm to form a solution, and passed the solution through an annular die (die lip opening 0.8mm, die Head temperature 200°C), blow molding into the first film bubble and cooling through the cooling ring, blow up ratio 1, traction ratio 1, after lamination, do shaping treatment, processing temperature 100°C, processing time 10s; The second film bubble is formed on the top, the preheating temperature is 100°C, the preheating time is 10s, the blow-up ratio is 1, and the traction ratio is 1; Finally, the liquid paraffin in the film is extracted with methyl ethyl ketone, and after drying, it is subjected to a setting treatment at 100° C., and the stretching ratio is 1.0 times, and the finished polyole...

Embodiment 2

[0031] 60% (weight) of polypropylene (melting point 167° C.) is dropped into a twin-screw extruder (78 mm in diameter, L / D=50, strong mixing type), and 40% ( weight) of solid paraffin, melted and kneaded under the conditions of 200°C and 150 rpm to form a solution, passed the solution through an annular die (die lip opening 0.8mm, die temperature 180°C), and blow molded as The first film bubble is cooled by the cooling ring, the inflation ratio is 5, the traction ratio is 5, and after lamination, it is shaped, the treatment temperature is 150°C, and the treatment time is 100s; after that, the second film bubble is formed on the basis of preheating, and the preheating temperature is 150 ℃, preheating time 100s, blowing ratio 5, traction ratio 5; after lamination, do shaping treatment, treatment temperature 150℃, treatment time 100s. Finally, the solid paraffin in the film is extracted with methyl ethyl ketone, and after drying, it is subjected to setting treatment at 150° C., a...

Embodiment 3

[0033] Put 20% (weight) of high-density polyethylene (melting point 133°C) into a twin-screw extruder (78mm in diameter, L / D=50, strong mixing type), and add 80% of it through the side feeding port with a metering pump. The dioctyl phthalate of % (weight), under the condition of 200 ℃, 150 rev / mins, melting kneading is modulated into solution, and this solution is passed through annular die head (die lip opening degree 0.8mm, die head temperature 240 ℃), blow molding into the first film bubble and cooling through the cooling ring, the blow-up ratio is 3, the traction ratio is 3, after lamination, the setting treatment is carried out, the treatment temperature is 125 ℃, and the treatment time is 30s; after that, the second bubble is formed on the basis of preheating. For film bubbles, the preheating temperature is 125°C, the preheating time is 30s, the blow-up ratio is 3, and the traction ratio is 3; after lamination, the shaping treatment is performed, the processing temperatur...

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PUM

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Abstract

The invention provides a method for preparing polyolefin microporous membranes with uniform structures, comprising the following steps of: (1) mixing polyolefin resin with a thinner, wherein the weight ratio of the polyolefin resin to the thinner is 1-6 : 4-9; (2) extruding and cooling the mixture through a finish mold by adopting an extrusion blow molding mode to form a first membrane; (3) carrying out forming treatment after superimposed traction; (4) preheating, stretching and blowing the first membrane bubble to form a second membrane bubble; (5) carrying out forming treatment after the superimposed traction; (6) extracting the thinner and drying; (7) transversely stretching for forming treatment; and (8) rolling. In the invention, a double-bubble tube blow molding mode is adopted, the first membrane bubble is formed on the basis of extrusion cooling loop cooling of an extruding machine firstly, then the second membrane bubble is formed by carrying out blowing traction on the basis of prewarming, the polyolefin microporous membranes are prepared by adopting extracting agent extraction and heat forming treatment, the phenomenon of uneven structure caused by different cooling of two surfaces and skid in the vertical stretching process is avoided in the extruding casting process, and products with uniform microcellular structure and good ventilation property can be obtained.

Description

technical field [0001] The invention relates to a preparation method of a plastic film, in particular to a preparation of a polyolefin microporous film. Background technique [0002] Due to its good chemical resistance, polyolefins are widely used in the manufacturing process of microporous membranes with harsh environments, such as separators for lithium-ion batteries. Polyolefin microporous film is a plastic film with numerous interconnected micropores with a pore size of 0.01-10 μm. The current industrial production methods of polyolefin microporous membranes mainly include melt stretching method and thermally induced phase separation method. [0003] The melt stretching method is to extrude a crystalline polymer (such as polypropylene) into a film under the condition of increasing the stress of the molten polymer, and then anneal the film under no tension or low tension to obtain the necessary crystal structure, and then carry out longitudinal stretching. Stretching cr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C08J9/00C08J9/26C08J9/28C08L23/00C08L23/06C08L23/12C08L23/16C08L23/20C08K13/02B29C49/04B29C55/04B29C47/92B29C49/78B29C48/92
CPCB29L2023/001B29K2995/005B29C55/28C08J2323/02C08L2207/32B29C47/0026B29C47/8825C08J5/18C08L23/02B29C48/10B29C48/91B29C48/912C08L2666/02
Inventor 陈秀蜂陈勇高东波杨梅
Owner SHENZHEN SENIOR TECH MATERIAL
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