CN111040236B - Polyethylene microporous membrane and preparation method thereof - Google Patents
Polyethylene microporous membrane and preparation method thereof Download PDFInfo
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- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof
- C08J9/28—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a liquid phase from a macromolecular composition or article, e.g. drying of coagulum
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- C08J2201/00—Foams characterised by the foaming process
- C08J2201/04—Foams characterised by the foaming process characterised by the elimination of a liquid or solid component, e.g. precipitation, leaching out, evaporation
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- C08J2323/00—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers
- C08J2323/02—Characterised by the use of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Derivatives of such polymers not modified by chemical after treatment
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Abstract
The invention discloses a polyethylene microporous membrane and a preparation method thereof. The method for preparing the polyethylene microporous membrane comprises the following steps: (1) mixing polyethylene resin and a diluent to obtain a blended melt, wherein the content of the polyethylene resin in the blended melt is 29-32 wt%; (2) extruding and rolling the blended melt to obtain a thick sheet; (3) stretching the slab to obtain an oil-containing base film, wherein the stretching treatment comprises longitudinal stretching treatment and transverse stretching treatment, and the temperature adopted in the transverse stretching treatment is 105-115 ℃; (4) subjecting said oil-bearing basement membrane to an extractive drying treatment to remove said diluent from said oil-bearing basement membrane; (5) and (5) carrying out heat setting treatment on the product obtained in the step (4) to obtain the polyethylene microporous membrane. The method for preparing the polyethylene microporous membrane is simple to operate and strong in controllability, and the prepared polyethylene microporous membrane has excellent strength, modulus and apparent mass.
Description
Technical Field
The invention relates to the technical field of lithium batteries, in particular to a method for preparing a high-modulus polyethylene microporous membrane by a wet method and the polyethylene microporous membrane prepared by the method.
Background
The wavy texture (shown in fig. 3) generated by the diaphragm produced by the process for manufacturing the lithium ion battery diaphragm by the wet method is a common problem of diaphragm manufacturers in the industry, and the wavy texture on the appearance is the most important defect of the battery diaphragm. When the diaphragm has too large ripples, the thickness of the coating layer becomes uneven when the coating layer is formed on the microporous membrane, and problems such as missing coating are easily caused, resulting in the reduction of the mechanical strength and other properties of the diaphragm. Therefore, it is necessary to research and improve the manufacturing method of the polyethylene microporous membrane, and reduce the generation of the raised grains, thereby preparing the polyethylene microporous membrane with higher quality.
In the technical solution disclosed in patent CN201220601524.2, a buffer material is disposed on the surface of the diaphragm, so that the buffer material can play a role in buffering when the film shrinks due to stress release or the film thickness gets tighter and tighter. But the deformation prevention effect is still not ideal, and the problem of the raised grains of the diaphragm cannot be effectively improved; in addition, the method for improving the wavy texture problem of the diaphragm by setting the rolling tension taper coefficient has limited effect, and is a measure for performing post-processing on the diaphragm which generates the wavy texture and preventing the wavy texture from aggravating.
In the technical solution disclosed in patent CN201380017899.1, the total length of the width of the raised grains is less than one fourth of the total width, in the embodiment, the minimum is also 4%, and the maximum width of the diaphragm is only 1.1 m. And no key technique for reducing the ripple is disclosed.
Disclosure of Invention
The present invention is directed to solving, at least to some extent, one of the technical problems in the related art. To this end, an object of the present invention is to propose a method for preparing a high modulus polyethylene microporous membrane by a wet process and a polyethylene microporous membrane prepared by the method. The method for preparing the polyethylene microporous membrane is simple to operate and strong in controllability, and the prepared polyethylene microporous membrane has excellent strength, modulus and apparent mass.
In one aspect of the present invention, there is provided a method for preparing a polyethylene microporous membrane, comprising: (1) mixing polyethylene resin and a diluent to obtain a blended melt, wherein the content of the polyethylene resin in the blended melt is 29-32 wt%; (2) extruding and rolling the blended melt to obtain a thick sheet; (3) stretching the slab to obtain an oil-containing base film, wherein the stretching treatment comprises longitudinal stretching treatment and transverse stretching treatment, and the temperature adopted in the transverse stretching treatment is 105-115 ℃; (4) subjecting said oil-bearing basement membrane to an extractive drying treatment to remove said diluent from said oil-bearing basement membrane; (5) and (5) carrying out heat setting treatment on the product obtained in the step (4) to obtain the polyethylene microporous membrane.
According to the method for preparing the polyethylene microporous membrane, a thick sheet is obtained by extruding and rolling the mixed solvent of the polyethylene resin and the diluent; then, longitudinally and transversely stretching the thick sheet to obtain an oil-containing base film; and then removing the diluent in the oil-containing base membrane through extraction drying treatment, and performing heat setting treatment to obtain a polyethylene microporous membrane product. According to the method, the proportion of the polyethylene resin in the blending melt and the technological parameters in the stretching treatment are optimized and adjusted, so that the strength, the modulus and other properties of the product can be obviously enhanced, the capacity of resisting external deformation of the product is improved, and the raised grains caused by uneven shrinkage in the extraction drying step are resisted, so that the polyethylene microporous membrane with higher quality is prepared. Meanwhile, the method has the advantages of simplicity in operation, strong controllability and the like.
In addition, the method for preparing a polyethylene microporous membrane according to the above embodiment of the present invention may further have the following additional technical features:
in some embodiments of the invention, the diluent comprises at least one selected from the group consisting of paraffin oil, dioctyl phthalate, dibutyl phthalate, oleyl alcohol, stearyl alcohol.
In some embodiments of the present invention, the temperature used in the rolling is 40 to 50 ℃.
In some embodiments of the present invention, the cross-machine direction stretching ratio used in the stretching process is 2 to 3.
In some embodiments of the present invention, the stretching rate used in the transverse stretching process is 40 to 50 mm/s.
In some embodiments of the present invention, the temperature used in the heat-setting treatment is 125 to 135 ℃.
In another aspect of the present invention, a polyethylene microporous membrane is provided. According to the embodiment of the present invention, the polyethylene microporous membrane is prepared by the method for preparing the polyethylene microporous membrane of the above embodiment. Therefore, the polyethylene microporous membrane has excellent performances such as strength, modulus and the like, and can effectively resist external deformation.
In addition, the microporous polyethylene membrane according to the above embodiment of the present invention may further have the following additional technical features:
in some embodiments of the present invention, the microporous polyethylene membrane has a longitudinal modulus of 1800 to 2000MPa and a transverse modulus of 2000 to 2300 MPa.
Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
Drawings
The above and/or additional aspects and advantages of the present invention will become apparent and readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:
FIG. 1 is a schematic flow diagram of a method for making a polyethylene microporous membrane according to one embodiment of the present invention;
FIG. 2 is a schematic representation of the corrugations in a polyethylene microporous membrane;
fig. 3 is a schematic representation of the corrugations in a polyethylene microporous membrane.
Detailed Description
The following describes in detail embodiments of the present invention. The following examples are illustrative only and are not to be construed as limiting the invention. The examples, where specific techniques or conditions are not indicated, are to be construed according to the techniques or conditions described in the literature in the art or according to the product specifications. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products commercially available.
In one aspect of the present invention, the present invention provides a method for preparing a polyethylene microporous membrane, comprising: (1) mixing polyethylene resin and a diluent to obtain a blended melt, wherein the content of the polyethylene resin in the blended melt is 29-32 wt%; (2) extruding and rolling the blended melt to obtain a thick sheet; (3) stretching the thick sheet to obtain an oil-containing base film, wherein the stretching treatment comprises longitudinal stretching treatment and transverse stretching treatment, and the temperature adopted in the transverse stretching treatment is 105-115 ℃; (4) carrying out extraction drying treatment on the oil-containing basement membrane so as to remove the diluent in the oil-containing basement membrane; (5) and (5) carrying out heat setting treatment on the product obtained in the step (4) to obtain a polyethylene microporous membrane product.
The inventor finds that the transverse modulus of the oil-containing base film obtained by the transverse stretching process is very small, only about 100-300 MPa, so that the diaphragm has very weak capacity of resisting external deformation, and the diaphragm is deformed by very small tension. And then in the subsequent extraction drying process, when the extractant volatilizes, capillary pressure causes the diaphragm micropore to shrink, the phenomenon that the diaphragm shrink of dry section is uneven appears. When the oil film has poor resistance to external deformation, the oil film is easy to generate raised grains. Further, through intensive research, the inventor finds that the strength, modulus and other properties of the product can be remarkably enhanced by optimizing and adjusting the proportion of the polyethylene resin in the blended melt and the process parameters in the stretching treatment, the capacity of resisting external deformation of the product is improved, and the raised grains caused by uneven shrinkage in the extraction drying step are resisted, so that the polyethylene microporous membrane with higher quality is prepared.
The method for preparing a polyethylene microporous membrane according to an embodiment of the present invention is further described in detail below. Referring to fig. 1, according to an embodiment of the invention, the method comprises:
s100: raw material blending
In the step, the polyethylene resin and the diluent are mixed to obtain a blended melt (wherein the content of the polyethylene resin is 29-32 wt%). Specifically, the polyethylene resin and the diluent may be fed into a kneading apparatus commonly used in the art, such as a twin-screw extruder, and melt-kneaded to obtain a blended melt.
According to some embodiments of the invention, the diluent comprises at least one selected from the group consisting of paraffin oil, dioctyl phthalate, dibutyl phthalate, oleyl alcohol, stearyl alcohol. The diluent has wide sources, is cheap and easy to obtain, and is easy to be removed by the extractant in the subsequent extraction and drying steps, and micropores with proper pore diameters are formed on the surface of the basement membrane.
According to some embodiments of the present invention, the content of the polyethylene resin in the above-mentioned blended melt may be 29 to 32 wt%, for example, 29 wt%, 29.5 wt%, 30 wt%, 30.5 wt%, 31 wt%, 31.5 wt%, 32 wt%, etc. The inventors have found that by controlling the polyethylene resin content within the above range, sufficient orientation of the thick sheet can be formed during stretching, ensuring sufficient mechanical strength of the separator. If the content of the polyethylene resin is too low, the mechanical strength of the film is reduced, resulting in large waves in the subsequent extraction drying process.
S200: extrusion and roll pressing
In the step, the blended melt is extruded and rolled to obtain a slab. Specifically, the blended melt can be conveyed to extrusion equipment in the field such as an extrusion die head through a metering pump for extrusion, and after a cast film is extruded, the blended melt is cooled and rolled through rolling equipment in the field such as a casting sheet roller, and cast into a thick sheet
According to some embodiments of the present invention, the temperature used in the rolling may be 40 to 50 ℃, for example, 40 ℃, 42.5 ℃, 45 ℃, 47.5 ℃, 50 ℃, etc. The polyethylene microporous film is prepared by pressing into a thick sheet at the temperature, and the strength, modulus and other properties of the polyethylene microporous film product are better. If the rolling temperature is too low, the film modulus may decrease and the corrugation may increase.
S300: stretching treatment
In the step, the slab is subjected to stretching treatment to obtain an oil-containing base film, wherein the stretching treatment comprises longitudinal stretching treatment (MDO) and transverse stretching Treatment (TDO), and the temperature adopted in the transverse stretching treatment is 105-115 ℃. In some embodiments, the oil-containing base film can be obtained by stretching the slab in the longitudinal direction using stretching equipment such as stretching rollers, etc. commonly used in the art, fixing the two sides of the film with clamps, and stretching the film in the transverse direction.
According to some embodiments of the invention, the cross-machine direction stretch ratio employed in the stretching process is 2 to 3, such as 2, 2.3, 2.4, 2.7, 3, etc. The longitudinal and transverse stretch ratio in the stretching treatment means a ratio of the longitudinal stretch ratio to the transverse stretch ratio. By controlling the transverse and longitudinal stretching ratio in the stretching treatment within the above range, the orientation of the polymer chains in the transverse direction can be further facilitated, the crystallinity of the polymer can be improved, and the transverse mechanical strength and modulus of the film can be further enhanced.
According to some embodiments of the present invention, the temperature used in the transverse stretching process may be 105 to 115 ℃, for example, 105 ℃, 108 ℃, 110 ℃, 113 ℃, 115 ℃ and the like. This can further facilitate the orientation of the polymer chain in the transverse direction, and facilitates the crystallization of the polymer. On the premise that molecular chain crystallization rearrangement is sufficiently performed, the strength and modulus of the film can be improved while the porosity of the film is reduced by adopting the transverse stretching temperature. If too high a temperature is used in the transverse stretching process, the pore size of the micropores may be too large, which may affect the mechanical properties of the film.
According to some embodiments of the invention, the stretching rate used in the transverse stretching process is 40-50 mm/s, such as 40mm/s, 42.5mm/s, 45mm/s, 47.5mm/s, 50mm/s, etc. By carrying out transverse stretching treatment at the stretching rate, the strength, modulus and other properties of the polyethylene microporous membrane product obtained by subsequent preparation are better. If the stretching rate is too low, the film modulus may be lowered and the number of waves may be increased.
S400: extraction drying treatment
In this step, the oil-containing basement membrane is subjected to extraction drying treatment to remove the diluent in the oil-containing basement membrane. The specific kind of the extractant used in the extraction drying treatment is not particularly limited as long as the diluent in the oil-containing base film can be effectively removed, and a common extractant such as methylene chloride can be used. In the preparation method of the high-modulus polyethylene microporous membrane, the proportion of the polyethylene resin in the blended melt and the process parameters in the stretching treatment are optimally adjusted in the steps S100-S300, so that the obtained oil-containing basement membrane has excellent properties such as strength, modulus and the like. The oily base film has strong capability of resisting external deformation in the extraction and drying treatment, and is not easy to generate raised grains.
S500: heat setting treatment
In the step, the product obtained in the step S400 is subjected to heat setting treatment to obtain a polyethylene microporous membrane product.
According to some embodiments of the invention, the temperature used in the heat-setting treatment is 125 to 135 ℃.
In another aspect of the present invention, a polyethylene microporous membrane is provided. According to the embodiment of the present invention, the polyethylene microporous membrane is prepared by the method for preparing the polyethylene microporous membrane of the above embodiment. Therefore, the polyethylene microporous membrane has excellent performances such as strength, modulus and the like, and can effectively resist external deformation.
According to some embodiments of the present invention, the longitudinal modulus of the microporous polyethylene membrane is 1800 to 2000MPa (e.g., 1800MPa, 1850MPa, 1900MPa, 1950MPa, 2000MPa, etc.), and the transverse modulus of the microporous polyethylene membrane is 2000 to 2300MPa (e.g., 2000MPa, 2050MPa, 2100MPa, 2150MPa, 2200MPa, 2250MPa, 2300MPa, etc.). Therefore, the polyethylene microporous membrane has excellent performances such as strength, modulus and the like, and can effectively resist external deformation.
In addition, it should be noted that all the features and advantages described above for the "method for preparing a polyethylene microporous membrane" are also applicable to the "polyethylene microporous membrane", and are not described in detail herein.
The invention will now be described with reference to specific examples, which are intended to be illustrative only and not to be limiting in any way. In addition, the raised grains in the membrane product are shown in fig. 2, Δ h is the height difference of the raised grains of the membrane, and d is the wavelength of the raised grains; fig. 2 is a schematic view of one corrugation in the longitudinal direction, while the longitudinal membrane comprises a plurality of corrugations in the longitudinal direction. The modulus test results are the average of the slopes of the stress-strain curves within 1% according to the elongation (strain) of the sample.
Example 1
(1) Mixing polyethylene resin and diluent paraffin oil according to a mass ratio of 30:70, and putting the mixture into a double-screw extruder for melting and mixing to obtain a blended melt.
(2) The blended melt was fed to an extrusion die through a metering pump, followed by extrusion of a cast film, and cast into a slab by cooling-rolling at 40 ℃ with a slab roll.
(3) And (3) longitudinally stretching the thick sheet by a stretching roller, wherein the longitudinal stretching ratio is 6, fixing two sides of the obtained film by using a clamp, and transversely stretching, wherein the transverse stretching ratio is 12, the transverse-longitudinal stretching ratio is 2, the transverse stretching speed is 50mm/s, and the transverse stretching temperature is 110 ℃ to obtain the oil-containing base film.
(4) And (3) extracting and drying the oil-containing base film by using dichloromethane, fixing two sides of the film by using a clamp, and performing transverse heat setting treatment to obtain a polyethylene microporous film product.
(5) And (3) rolling the polyethylene microporous membrane product, and performing performance test. The longitudinal modulus of the product is 1800MPa, the transverse modulus is 2100MPa, the sum of the widths of the raised grains accounts for 1/30 of the total width of the diaphragm, and the height difference delta h of the raised grains of the diaphragm is 8 mm.
Example 2
(1) Mixing polyethylene resin and diluent paraffin oil according to the mass ratio of 29:71, and putting the mixture into a double-screw extruder for melt mixing to obtain a blended melt.
(2) The blended melt was fed to an extrusion die through a metering pump, followed by extrusion of a cast film, and cast into a slab by cooling-rolling at 40 ℃ with a slab roll.
(3) And (3) longitudinally stretching the thick sheet by a stretching roller at a longitudinal stretching ratio of 7, fixing two sides of the obtained film by using a clamp, and transversely stretching the thick sheet at a transverse stretching ratio of 17, a transverse-longitudinal stretching ratio of about 2.4, a transverse stretching speed of 45mm/s and a transverse stretching temperature of 105 ℃ to obtain the oil-containing base film.
(4) And (3) extracting and drying the oil-containing base film by using dichloromethane, fixing two sides of the film by using a clamp, and performing transverse heat setting treatment to obtain a polyethylene microporous film product.
(5) And (4) rolling the polyethylene microporous membrane product, and performing performance test. The longitudinal modulus of the product is 1900MPa, the transverse modulus of the product is 2250MPa, the sum of the wave widths accounts for 1/40 of the total width of the diaphragm, and the height difference delta h of the wave patterns of the diaphragm is 5 mm.
Example 3
(1) Mixing polyethylene resin and diluent paraffin oil according to a mass ratio of 31:69, and putting the mixture into a double-screw extruder for melt mixing to obtain a blended melt.
(2) The blended melt was fed to an extrusion die through a metering pump, followed by extrusion of a cast film, and cast into a slab by cooling roll pressing at 47 ℃.
(3) And (3) longitudinally stretching the thick sheet by a stretching roller, wherein the longitudinal stretching ratio is 6.5, fixing two sides of the obtained film by a clamp, and transversely stretching, wherein the transverse stretching ratio is 17, the transverse-longitudinal stretching ratio is about 2.3, the transverse stretching speed is 40mm/s, and the transverse stretching temperature is 113 ℃ to obtain the oil-containing base film.
(4) And (3) extracting and drying the oil-containing base film by using dichloromethane, fixing two sides of the film by using a clamp, and performing transverse heat setting treatment to obtain a polyethylene microporous film product.
(5) And (4) rolling the polyethylene microporous membrane product, and performing performance test. The longitudinal modulus of the product is 1850MPa, the transverse modulus is 2200MPa, the sum of the wave widths accounts for 1/35 of the total width of the diaphragm, and the height difference delta h of the wave widths of the diaphragm is 8 mm.
Comparative example 1
(1) Mixing polyethylene resin and diluent paraffin oil according to a mass ratio of 25:75, and putting the mixture into a double-screw extruder for melting and mixing to obtain a blended melt.
(2) The blended melt was fed to an extrusion die through a metering pump, followed by extrusion of a cast film, and cast into a slab by cooling roll pressing at 25 ℃ using a slab roll.
(3) And (3) longitudinally stretching the thick sheet by a stretching roller, wherein the longitudinal stretching ratio is 6.7, fixing two sides of the obtained film by a clamp, and transversely stretching, wherein the transverse stretching ratio is 7, the transverse and longitudinal stretching ratio is about 1, the transverse stretching speed is 20mm/s, and the transverse stretching temperature is 120 ℃ to obtain the oil-containing base film.
(4) And (3) extracting and drying the oil-containing base film by using dichloromethane, fixing two sides of the film by using a clamp, and performing transverse thermal relaxation treatment to obtain a polyethylene microporous film product.
(5) And (4) rolling the polyethylene microporous membrane product, and performing performance test. The longitudinal modulus of the product is 1600MPa, the transverse modulus is 800MPa, the sum of the widths of the raised grains accounts for 1/10 of the total width of the diaphragm, and the height difference delta h of the raised grains of the diaphragm is 15 mm.
Comparative example 2
(1) Mixing polyethylene resin and diluent paraffin oil according to a mass ratio of 25:75, and putting the mixture into a double-screw extruder for melt mixing to obtain a blended melt.
(2) The blended melt was fed to an extrusion die through a metering pump, followed by extrusion of a cast film, and cast into a slab by cooling roll pressing at 28 ℃ using a slab roll.
(3) And (3) longitudinally stretching the thick sheet by a stretching roller at a longitudinal stretching ratio of 7, fixing two sides of the obtained film by using a clamp, and transversely stretching the thick sheet at a transverse stretching ratio of 7, a transverse and longitudinal stretching ratio of 1, a transverse stretching speed of 20mm/s and a transverse stretching temperature of 118 ℃ to obtain the oil-containing base film.
(4) And (3) extracting and drying the oil-containing base film by using dichloromethane, fixing two sides of the film by using a clamp, and performing transverse thermal relaxation treatment to obtain a polyethylene microporous film product.
(5) And (4) rolling the polyethylene microporous membrane product, and performing performance test. The longitudinal modulus of the product is 1700MPa, the transverse modulus is 960MPa, the sum of the widths of the raised grains accounts for 1/15 of the total width of the diaphragm, and the height difference delta h of the raised grains of the diaphragm is 25 mm.
In the description of the specification, reference to the description of "one embodiment," "some embodiments," "an example," "a specific example," or "some examples" or the like means that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.
Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention, and that variations, modifications, substitutions and alterations can be made to the above embodiments by those of ordinary skill in the art within the scope of the present invention.
Claims (5)
1. A method of making a polyethylene microporous membrane, comprising:
(1) mixing polyethylene resin with a diluent to obtain a blended melt, wherein the content of the polyethylene resin in the blended melt is 29-32 wt%;
(2) extruding and rolling the blended melt to obtain a thick sheet;
(3) stretching the slab to obtain an oil-containing base film, wherein the stretching treatment comprises longitudinal stretching treatment and transverse stretching treatment, and the temperature adopted in the transverse stretching treatment is 105-115 ℃;
(4) subjecting the oil-containing base film to an extraction drying treatment to remove the diluent from the oil-containing base film;
(5) performing heat setting treatment on the product obtained in the step (4) to obtain the polyethylene microporous membrane,
in the step (2), the temperature adopted in the rolling is 40-50 ℃,
in the step (3), the transverse and longitudinal stretching ratio adopted in the stretching treatment is 2-3, and the stretching rate adopted in the transverse stretching treatment is 40-50 mm/s.
2. The method of claim 1, wherein the diluent comprises at least one selected from the group consisting of paraffin oil, dioctyl phthalate, dibutyl phthalate, oleyl alcohol, and stearyl alcohol.
3. The method according to claim 1, wherein the temperature used in the heat-setting treatment is 125 to 135 ℃.
4. A microporous polyethylene membrane prepared by the method according to any one of claims 1 to 3.
5. The microporous polyethylene membrane of claim 4, wherein the microporous polyethylene membrane has a longitudinal modulus of 1800 to 2000MPa and a transverse modulus of 2000 to 2300 MPa.
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| CN1887581A (en) * | 2005-06-30 | 2007-01-03 | 佛山塑料集团股份有限公司 | Making process of microporous polyolefin film |
| CN103094514A (en) * | 2011-11-03 | 2013-05-08 | 温朝亮 | Diaphragm for lithium ion batteries and preparation method thereof |
| CN103022401A (en) * | 2012-12-31 | 2013-04-03 | 新乡市中科科技有限公司 | Preparation method of lithium-ion polyolefin membrane |
| CN103465476A (en) * | 2013-09-03 | 2013-12-25 | 深圳中兴创新材料技术有限公司 | Polyolefin microporous membrane as well as preparation method and application thereof |
| CN104362276A (en) * | 2014-10-27 | 2015-02-18 | 中国乐凯集团有限公司 | Polyethylene microporous membrane, preparation method and lithium ion battery |
| CN110165123A (en) * | 2019-05-15 | 2019-08-23 | 乐凯胶片股份有限公司 | Polyethene microporous membrane and its preparation method and application |
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