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Method for preparing polyolefin micro-porous film

A polyolefin microporous film and polyolefin technology, applied in flat products, household utensils, and other household utensils, etc., can solve problems such as rough electrode surface, diaphragm pressure, affecting battery cycle life, service efficiency and safety characteristics, etc. , to achieve fast absorption of electrolyte, small change in air permeability, and meet the requirements of use

Inactive Publication Date: 2012-11-14
CHONGQING YUNTIANHUA NEWMI-TECH CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Since polyolefin is a hydrophobic material, the liquid absorption of the electrolyte is poor. With the requirement of high capacity of the lithium-ion battery, the liquid absorption performance of the separator must be improved; during the charging and discharging process of the lithium-ion battery, with the Insertion and de-intercalation in the positive and negative electrode materials, the positive and negative electrode materials expand and contract. When the positive and negative electrodes expand and contract, the diaphragm will withstand a pressure of up to tens of kilograms per square centimeter. In addition, the surface of the electrode is not smooth. , will also cause pressure on the diaphragm, which will affect the cycle life, efficiency and safety characteristics of the battery
With the high capacity, high rate and application of new electrode systems in recent years, higher requirements have been put forward for the electrolyte liquid absorption, pressure resistance and puncture strength of the battery separator, while the traditional process preparation It is difficult for microporous membranes to take into account these properties

Method used

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  • Method for preparing polyolefin micro-porous film
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Examples

Experimental program
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Effect test

Embodiment 1

[0025] The preparation method of the polyolefin microporous membrane of the present embodiment comprises the steps:

[0026] (a), 25 parts by mass of ultra-high molecular weight polyethylene (weight average molecular weight 1×10 6 ), add 0.025 parts by mass of antioxidant 1010 {tetrakis[methyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester} and 0.5 parts by mass of nucleating Silica powder, then added to a twin-screw extruder (diameter 110mm, L / D=52), 75 parts by mass of liquid paraffin was injected from the middle of the twin-screw extruder through a metering pump, at 210°C, 100r / min Melting and kneading under the same conditions to prepare polyolefin homogeneous melt;

[0027] (b) The polyolefin homogeneous melt is extruded from the flat film die at the front end of the extruder to form a molding melt, and the molding melt is drawn out with a cooling roller A whose temperature is adjusted to 18°C. Roll A is contacted and cooled for 30s. After surfa...

Embodiment 2

[0032] The preparation method of the polyolefin microporous membrane of the present embodiment comprises the steps:

[0033] (a), 10 parts by mass of ultra-high molecular weight polyethylene (weight average molecular weight 1.5×10 6 ), 17 parts by mass of polypropylene (weight average molecular weight 2.5×10 5 ) and 3 parts by mass of terpolymerized polypropylene (weight average molecular weight 1×10 5 ), add 0.03 parts by mass of antioxidant 1010 {tetrakis[methyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester} and 0.6 parts by mass of nucleating Silica powder, then added to a twin-screw extruder (diameter 110mm, L / D=52), 70 parts by mass of liquid paraffin was injected from the middle of the twin-screw extruder through a metering pump, at 235°C, 100r / min Melting and kneading under the same conditions to prepare polyolefin homogeneous melt;

[0034] (b) The polyolefin homogeneous melt is extruded from the flat film die at the front end of the extrud...

Embodiment 3

[0039] The preparation method of the polyolefin microporous membrane of the present embodiment comprises the steps:

[0040] (a), 12 parts by mass of ultra-high molecular weight polyethylene (weight average molecular weight 1.5×10 6 ) and 15 parts by mass of high-density polyethylene (weight-average molecular weight 4×10 5 ), add 0.027 parts by mass of antioxidant 1010 {tetrakis[methyl-β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate] pentaerythritol ester} and 0.54 parts by mass of nucleating Silica powder, then added to a twin-screw extruder (diameter 110mm, L / D=52), 73 parts by mass of liquid paraffin was injected from the middle of the twin-screw extruder through a metering pump, at 210°C, 100r / min Melting and kneading under the same conditions to prepare polyolefin homogeneous melt;

[0041] (b) The polyolefin homogeneous melt is extruded from the flat film die at the front end of the extruder to become a molding melt, and the molding melt is drawn out with a cooling ro...

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Abstract

The invention discloses a method for preparing polyolefin micro-porous film. The method includes fusing and mixing a polyolefin resin and a film forming solvent in an extruder to prepare a polyolefin homogeneous melt; extruding the polyolefin homogeneous melt from a flat film die to form a molded melt, imposing various temperature fields on the surface of the molded melt for cooling, and imposing a shear force in the thickness direction during the cooling to form sheets; preheating the sheets, and performing longitudinal or bidirectional drawing on the sheets to form micro fibrillated film; extracting the film forming solvent in the micro fibrillated film with an extraction solvent, and drying the film forming solvent to form micro-porous film; preheating the micro-porous film, and subjecting the micro-porous film to secondary drawing and heat shaping. According to the method for preparing polyolefin micro-porous film, the pore diameter of the micro-porous film changes in the film thickness direction, and a compact structure layer and a coarse pore diameter structure layer are provided. The micro-porous film has the advantages of being rapid in electrolyte absorption, high in puncture strength, small in air permeability change and the like, and can meet the use requirements of lithium ion battery diaphragms.

Description

technical field [0001] The invention relates to a preparation method of a polyolefin microporous membrane, in particular to a preparation method of a polyolefin microporous membrane suitable for lithium-ion battery separators. Background technique [0002] Microporous membrane is a very versatile filter medium, which can be used for gas separation, reverse osmosis, nanofiltration, ultrafiltration and microfiltration according to the different pore sizes of microporous membranes. Due to its low price, excellent mechanical properties and chemical corrosion resistance, polyolefin microporous membranes are widely used in capacitor separators, battery separators and various separation membranes. [0003] In the known technology, the existing preparation methods of polyolefin microporous membranes mainly include melt stretching method and thermally induced phase separation method. The melt stretching method includes melting the polymer, extruding into a film, annealing to increas...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B29C69/00C08J9/28B29K23/00B29L7/00
Inventor 谢新春王志春刘超
Owner CHONGQING YUNTIANHUA NEWMI-TECH CO LTD
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