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Ultrathin high-strength polyolefin microporous film and preparation method thereof

A polyolefin microporous film, polyolefin technology, applied in the direction of coating, can solve the problems of easy thermal oxidation, mechanical degradation, lower yield, easy carbonization of polyolefin resin, etc., to ensure anti-oxidation effect, easy process flow The effect of simple operation and process flow

Active Publication Date: 2014-07-16
SHENZHEN SENIOR TECH MATERIAL
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, the molecular chain of polyolefin resin is relatively long and it is a non-polar crystalline polymer. In the stage of melting and heating, due to the effect of high temperature and strong shear, the molecular chain of polyolefin is easy to be thermally oxidized and mechanically degraded, which makes the chemical bonds of the molecular chain Break into active free radicals and hydroperoxides, and hydroperoxides are further decomposed to produce alkoxyl radicals and hydroxyl radicals, leading to a series of free radical chain reactions that cause fundamental changes in the structure and properties of polyolefin resins
At the same time, in the extrusion solid conveying stage, the polyolefin resin is easy to carbonize due to the shearing high temperature, and its carbonized fine particles will be extruded with the melt during casting, which will eventually cause crystal points or other bad problems on the film. Cause product quality problems and reduce yield
In addition, resin carbides are also easy to accumulate in the twin-screw extruder, and the screw needs to be removed to remove it, which will have a huge impact on production, undoubtedly greatly increase processing costs, waste valuable production time, and reduce production efficiency

Method used

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  • Ultrathin high-strength polyolefin microporous film and preparation method thereof
  • Ultrathin high-strength polyolefin microporous film and preparation method thereof

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preparation example Construction

[0026] A method for preparing an ultra-thin high-strength polyolefin microporous membrane, which uses polyolefin resin as a raw material and adopts the principle of thermally induced phase separation to prepare a polyolefin porous membrane, comprising the following steps:

[0027] a. Polyolefin swelling and dissolving: dissolve the antioxidant in the diluent in the kneader, add polyolefin resin powder into the diluent and stir evenly. Swelling polyolefin; under the protection of nitrogen, add diluent to the swelling polyolefin, dissolve at 100-400°C to form a mixture;

[0028] b. Cast sheet: The mixture obtained in the previous step is sent into the extruder by the gear delivery pump, and the extruder is used to plasticize the mixture to form a polyolefin solution, and the obtained polyolefin solution is extruded from the die under the control of the metering pump , to obtain a polyolefin melt;

[0029] c. Primary stretching of polyolefin cast film: After the polyolefin melt ...

Embodiment 1

[0040] (1) Under the protection of nitrogen, first dissolve the antioxidant in the diluent, then add the polyolefin resin and the diluent to the kneader to swell and dissolve. The mass ratio of antioxidant to polyolefin resin is 1:8000, the mass ratio of polyolefin to diluent is 1:3, the swelling temperature is 100°C, and the dissolution temperature is 250°C.

[0041] The antioxidant in this embodiment is dioctadecyl pentaerythritol diphosphite, the polyolefin resin is an ultra-high molecular weight polyethylene resin with a weight average molecular weight of 2 million, and the diluent is paraffin oil.

[0042] (2) Add the mixture obtained by swelling and dissolving into the extruder through the gear pump, and obtain a uniform melt through mixing, dispersing and shearing. The sheet is cooled by the quenching roll, and then made into a polyethylene microporous membrane product through biaxial stretching, extraction and drying. The temperature of the extruder is 100-300° C., an...

Embodiment 2

[0044] (1) Under the protection of nitrogen, first dissolve the antioxidant in the diluent, then add the polyolefin resin and the diluent to the kneader to swell and dissolve. The mass ratio of antioxidant to polyolefin resin is 1:8000, the mass ratio of polyolefin to diluent is 1:3, the swelling temperature is 100°C, and the dissolution temperature is 250°C.

[0045] The antioxidant in this embodiment is dioctadecyl pentaerythritol diphosphite, the polyolefin resin is an ultra-high molecular weight polyethylene resin with a weight average molecular weight of 5 million, and the diluent is paraffin oil.

[0046] (2) Add the mixture obtained by swelling and dissolving into the extruder through the gear pump, and obtain a uniform melt through mixing, dispersing and shearing. The sheet is cooled by the quenching roll, and then made into a polyethylene microporous membrane product through biaxial stretching, extraction and drying. The temperature of the extruder is 100-300° C., an...

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Abstract

The invention discloses a preparation method of an ultrathin high-strength polyolefin microporous film. Polyolefin resin is used as a raw material, and the polyolefin microporous film is prepared by a thermally induced phase separation principle. The method comprises the following steps: a. polyolefin swelling dissolving; b. sheet casting; c. stretching a polyolefin cast film once; and d. stretching the polyolefin cast film secondarily. The invention also discloses the polyolefin microporous film prepared by the method. The method has the advantages of semi-continuous production convenience, simple process flow and simplicity in operation.

Description

technical field [0001] The invention relates to a lithium-ion secondary battery, in particular to a preparation method of an ultra-thin high-strength polyolefin microporous membrane capable of convenient semi-continuous production and simple and easy-to-operate process flow and the polyolefin microporous membrane. Background technique [0002] Due to the good chemical stability and excellent physical properties of polyolefin, its microporous membrane separator is widely used in the fields of batteries, capacitors, water treatment, water desalination, biomedical and medical applications, especially as a separator for lithium-ion batteries. In the prior art, methods for preparing polyolefin microporous membranes include dry process (uniaxial stretching and biaxial stretching) and wet process (thermally induced phase separation method). Compared with other methods, the wet process can produce thinner microporous membranes with uniform thickness and excellent physical properties...

Claims

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Application Information

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IPC IPC(8): B29C69/00B29C47/00B29C55/12B29C41/26C08L23/06C08K5/524
Inventor 王郗肖武华刘瑞高东波
Owner SHENZHEN SENIOR TECH MATERIAL
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