Polyolefin film and preparation method thereof

A film preparation and polyolefin technology, applied in electrical components, circuits, battery pack components, etc., can solve the problems of large aperture, battery short circuit, and reduced adaptability of different raw materials, etc., to achieve the effect of small structure and large quantity

Active Publication Date: 2011-11-16
SINOMA LITHIUM BATTERY SEPARATOR CO LTD
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  • Abstract
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  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The post-extraction treatment is carried out after the end of stretching. The main material film network and the pore-forming agent have phase separation, but the pore-forming agent is still distributed between the molecular chains that have been bidirectionally oriented and stretched. At this time, the pore-forming agent After the extraction process, the pore diameter of the displaced hole is large, and the contact between the two electrodes cannot be well pr...

Method used

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  • Polyolefin film and preparation method thereof
  • Polyolefin film and preparation method thereof
  • Polyolefin film and preparation method thereof

Examples

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preparation example Construction

[0029] The preparation method of polyolefin film of the present invention is that polyolefin resin and low molecular weight compound (pore forming agent) (one of them Isopar E oil, Isopar F oil or paraffin oil) under higher temperature (150-200 ℃) melted and mixed evenly.

[0030] see figure 1 , the melt extruded through the extruder die (for extruding the melt of resin and pore-forming agent) 1 passes through longitudinal cooling rolls 2 and 3, and transverse cooling roll 4 in turn, and the melt is cooled after passing through three sets of cooling rolls Become a solid slab, coiled and wound.

[0031] see figure 2 , the cooled slab is extracted and heated and dried by one of N,N-dimethylformamide, dichloromethane and chloroform ( figure 2 ). Specifically, the slab passes through the roller 5 positioned in the trough 6 containing the extractant, passes between the heating and drying devices 11 and 12, and passes through the roller 5 positioned in the trough 10 containing...

Embodiment 1

[0043] The selected polyolefin resin is ultra-high-density polyethylene resin particles with a molecular weight of 4 million, and the pore-forming agent used is liquid paraffin oil; the weight ratio of oil powder is 15%, and the melting temperature is 150 ° C. It is melted and extruded through an extruder. The temperature of the cooling roll 2 was 70°C, the temperature of the cooling roll 3 was 63°C, and the temperature of the cooling roll 4 was 56°C. The extraction solvent in the extraction unit is N,N-dimethylformamide, the solvent is miscible with water in the feed tank 6, the volume ratio of the solvent is 80%, and the volume ratio of the solvent in the feed tank 10 is 60%. The temperature of heaters 11 and 12 is 155° C., the temperature of heaters 13 and 14 is 160° C., and the speed of extraction is 10 m / min. Carry out the first step of longitudinal stretching with a stretching ratio of 7 times, the stretching temperature is 113° C., and the stretching line speed is 20 m / ...

Embodiment 2

[0045] The selected polyolefin resin is isotactic polypropylene resin particles with a molecular weight of 200,000, and the pore-forming agent used is Isopar E oil; the weight ratio of oil to powder is 20%, and the melting temperature is 220° C., which is melted and extruded through an extruder. The temperature of the cooling roll 2 was 170°C, the temperature of the cooling roll 3 was 150°C, and the temperature of the cooling roll 4 was 130°C. The extraction solvent in the extraction unit is dichloromethane, and the solvent in feed tanks 6 and 10 is 100% solvent. The temperature of the heaters 11 and 12 is 55° C., the temperature of the heaters 13 and 14 is 60° C., and the extraction speed is 10 m / min. Carry out the first step of longitudinal stretching with a stretching ratio of 4 times, the stretching temperature is 170° C.; the stretching line speed is 15 m / min. Carry out the second step of biaxial stretching, the final stretching ratio in the transverse direction is 1:6, ...

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Abstract

The invention provides a polyolefin film prepared by a wet multi-step stretching process as well as a preparation method and a device thereof. The prepared film has the thickness of 10-100 mu m, permeability of 10-150 S/in<2>.100 cc.1.22 kPa, average pore diameter of 100-1000 nm, film breaking temperature of 110-160 DEG C, tensile strength of 50-250 MPa, puncture strength of 200-500 g/mu m and porosity of 25-45%. The polyolefin film is prepared by melting polyolefin resins and a pore-forming agent at a higher temperature for uniformly mixing, extruding a melt by an extruder die head 1, and cooling the extruded melt with a vertical cooling roll and a horizontal cooling roll to obtain a solid thick slice; and extracting and heating and drying the cooled thick slice, passing the thick slice through the resins treated by first-step vertical stretching orientation, second-step bidirectional synchronous stretching and third-step lateral expansion stretching as well as sintering and sizing at the sintering temperature of 120-200 DEG C to obtain the polyolefin film.

Description

[0001] Field [0002] The present invention relates to widely used microporous membranes, such as separation membranes used for the separation of substances, selective permeation, etc., as isolation materials for electrochemical reaction devices such as alkaline, lithium ion or fuel cells, etc. The invention relates to a polyolefin microporous film used for separators of non-aqueous electrolyte batteries such as batteries, and also relates to a preparation method of the olefin microporous film. Background technique [0003] The lithium-ion battery separator is one of the most important and indispensable components in the lithium-ion battery. At present, the wet production process for the production of lithium-ion battery separators in the world is to mix hydrocarbons or low-molecular-weight substances with polyolefin resins at relatively high temperatures, melt the cast sheets, and then perform orientation treatment on the sheets in the longitudinal or biaxial direction, and f...

Claims

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Application Information

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IPC IPC(8): C08J9/28C08L23/00B29C55/12B29C67/04H01M2/16
CPCY02E60/12Y02E60/10
Inventor 琚晓晖陈春吴敏马驰刘金云赵东波
Owner SINOMA LITHIUM BATTERY SEPARATOR CO LTD
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