WO2022127224A1 - 一种聚烯烃微多孔膜及其生产系统、电池隔膜、电化学装置 - Google Patents

一种聚烯烃微多孔膜及其生产系统、电池隔膜、电化学装置 Download PDF

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WO2022127224A1
WO2022127224A1 PCT/CN2021/118236 CN2021118236W WO2022127224A1 WO 2022127224 A1 WO2022127224 A1 WO 2022127224A1 CN 2021118236 W CN2021118236 W CN 2021118236W WO 2022127224 A1 WO2022127224 A1 WO 2022127224A1
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Prior art keywords
polyolefin microporous
microporous membrane
pore
forming agent
stretching
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PCT/CN2021/118236
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English (en)
French (fr)
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程跃
宫晓明
彭锟
虞少波
庄志
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上海恩捷新材料科技有限公司
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Priority to EP21905156.2A priority Critical patent/EP4265670A1/en
Priority to US18/034,652 priority patent/US20230395936A1/en
Priority to KR1020237016138A priority patent/KR20230124890A/ko
Priority to JP2023528044A priority patent/JP2023548238A/ja
Publication of WO2022127224A1 publication Critical patent/WO2022127224A1/zh

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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/18—Manufacture of films or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • 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
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/20—Manufacture of shaped structures of ion-exchange resins
    • C08J5/22—Films, membranes or diaphragms
    • C08J5/2206—Films, membranes or diaphragms based on organic and/or inorganic macromolecular compounds
    • C08J5/2218—Synthetic macromolecular compounds
    • C08J5/2231—Synthetic macromolecular compounds based on macromolecular compounds obtained by reactions involving unsaturated carbon-to-carbon bonds
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J5/00—Manufacture of articles or shaped materials containing macromolecular substances
    • C08J5/20—Manufacture of shaped structures of ion-exchange resins
    • C08J5/22—Films, membranes or diaphragms
    • C08J5/2287—After-treatment
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • 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
    • C08J9/26—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof by elimination of a solid phase from a macromolecular composition or article, e.g. leaching out
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/403—Manufacturing processes of separators, membranes or diaphragms
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/411—Organic material
    • H01M50/414—Synthetic resins, e.g. thermoplastics or thermosetting resins
    • H01M50/417—Polyolefins
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/409—Separators, membranes or diaphragms characterised by the material
    • H01M50/449—Separators, membranes or diaphragms characterised by the material having a layered structure
    • H01M50/451—Separators, membranes or diaphragms characterised by the material having a layered structure comprising layers of only organic material and layers containing inorganic material
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/491—Porosity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
    • H01M50/00—Constructional details or processes of manufacture of the non-active parts of electrochemical cells other than fuel cells, e.g. hybrid cells
    • H01M50/40—Separators; Membranes; Diaphragms; Spacing elements inside cells
    • H01M50/489—Separators, membranes, diaphragms or spacing elements inside the cells, characterised by their physical properties, e.g. swelling degree, hydrophilicity or shut down properties
    • H01M50/494—Tensile strength
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • 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
    • C08J2201/054—Precipitating the polymer by adding a non-solvent or a different solvent
    • C08J2201/0542—Precipitating the polymer by adding a non-solvent or a different solvent from an organic solvent-based polymer composition
    • C08J2201/0543—Precipitating the polymer by adding a non-solvent or a different solvent from an organic solvent-based polymer composition the non-solvent being organic
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • 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
    • C08J2323/04—Homopolymers or copolymers of ethene
    • C08J2323/06—Polyethene
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
    • Y02E60/10—Energy storage using batteries

Definitions

  • the invention relates to the field of battery separators, in particular to a polyolefin microporous membrane and a production system thereof, a battery separator and an electrochemical device.
  • Polyolefin microporous membranes are commonly used in various applications such as battery separators, electrolytic capacitor separators, ultrafiltration membranes, microfiltration membranes, and medical membranes. Whether it is a digital lithium-ion battery or a power lithium-ion battery, on the basis of ensuring the performance of the diaphragm, thinning has become a trend.
  • the thinning of the polyolefin microporous membrane can increase the number of stacks of electrode layers, which is beneficial to improve the energy density and capacity of lithium batteries, thereby making it possible to achieve high output.
  • the disadvantage of the existing ultra-thin polyolefin microporous membrane is that its strength is poor, and when it is used as a spacer membrane to be wound with an electrode at a high tension, the existing ultra-thin polyolefin microporous membrane is prone to breakage. Therefore, the existing technology still cannot produce ultra-thin high-strength diaphragms with uniform thickness and stable quality.
  • a method for preparing a lithium-ion battery diaphragm uses ultra-high molecular polyethylene as the main material to prepare a diaphragm with a thickness of 20 ⁇ m and good strength.
  • a method for preparing a lithium ion battery separator uses polyethylene with a viscosity average molecular weight of more than 100,000 to prepare a diaphragm with specific thickness, air permeability, porosity and tensile elongation.
  • the separator has a thickness of 20-40 ⁇ m.
  • the formula and method disclosed in the above-mentioned patent and patent application solve the problem of film strength in the traditional technology, but there are still the following defects, that is, the problem that the thickness of the diaphragm is too thick, and the requirements of ultra-thin and high-strength cannot be achieved.
  • the technical difficulty of the ultra-thin high-strength polyolefin microporous membrane is that the thickness, strength and porosity of the ultra-thin membrane cannot be taken into account, and the thickness uniformity of the membrane is poor.
  • the purpose of the present invention is to provide a polyolefin microporous membrane in order to overcome the above-mentioned defects of the prior art, which has high porosity, ultra-thin, high strength and good thickness uniformity, and can improve the Battery performance and lower battery costs.
  • One object of the present invention is to provide a polyolefin microporous membrane, which has a thickness of 2-30 ⁇ m and a puncture strength of 1000-2000 gf.
  • the tensile strength in the MD direction is 3200 to 5000 kgf/cm 2
  • the tensile strength in the TD direction is 2800 to 4800 kgf/cm 2 .
  • the elongation in the MD direction is 47 to 98%, and the elongation in the TD direction is 63 to 110%.
  • the porosity is 40%-57%
  • the maximum pore diameter is 33-48nm
  • the gas permeation rate is 10-400 seconds/100ml.
  • the impedance is 0.3 to 0.9 ⁇ /cm 2 .
  • polyolefin microporous membrane is composed of polyethylene with a weight average molecular weight of 4.0-8.0 ⁇ 10 6 .
  • Another object of the present invention is to provide a system for producing any of the above-mentioned polyolefin microporous membranes, which sequentially comprises a biaxial extruder, a casting machine, a pore former removing unit, a first stretching device, The second stretching device, heat treatment machine, coiler.
  • the pore-forming agent removal unit includes a tank body, a driving heat roller, a driven heat roller, and a pore-forming agent removal liquid; the tank body is a sealed tank body, and the polyolefin microporous sheet from the casting machine passes through the path. Designed for open sections.
  • the pore-forming agent removal liquid is located in the sealing tank; the position of the driving heat roller is higher than the liquid level of the pore-forming agent removal liquid; the driven heat roller is immersed in the pore-forming agent removal liquid. in liquid.
  • the second stretching device and the heat treatment machine are integrated together.
  • Another object of the present invention is to provide a battery separator comprising any of the above-mentioned polyolefin microporous membranes.
  • the diaphragm is one of a ceramic coating diaphragm, a PVDF coating diaphragm, and an aramid coating diaphragm.
  • Another object of the present invention is to provide an electrochemical device comprising any of the above-mentioned polyolefin microporous membranes or any of the battery separators as elements separating the positive and negative electrodes.
  • the beneficial effect of the present invention lies in that, compared with the existing microporous film, the polyolefin microporous film prepared by the method of the present invention can better satisfy the applications that have higher requirements on the thickness uniformity, ultra-thinness and high strength of the microporous film , especially suitable for the field of power lithium-ion battery separator.
  • FIG. 1 is a schematic diagram of a porogen removal unit according to an embodiment of the present invention
  • Fig. 2 is the preparation process flow chart of prior art polyolefin microporous membrane
  • Fig. 3 is the preparation process flow chart of the polyolefin microporous membrane of an embodiment of the present invention.
  • Fig. 4 is the preparation process flow chart of the polyolefin microporous membrane of another embodiment of the present invention.
  • the specific embodiment of the present invention provides a polyolefin microporous film, the film thickness of which is 2-30 ⁇ m and the puncture strength is 1000-2000 gf.
  • the tensile strength in the MD direction is 3200 to 5000 kgf/cm 2
  • the tensile strength in the TD direction is 2800 to 4800 kgf/cm 2 .
  • the elongation in the MD direction is 47 to 98%, and the elongation in the TD direction is 63 to 110%.
  • the porosity is 40%-57%
  • the maximum pore diameter is 33-48nm
  • the gas permeation rate is 10-400 seconds/100ml.
  • the impedance is 0.3 to 0.9 ⁇ /cm 2 .
  • polyolefin microporous membrane is composed of polyethylene with a weight average molecular weight of 4.0-8.0 ⁇ 10 6 .
  • a specific embodiment of the present invention also provides a system for producing any of the above-mentioned polyolefin microporous membranes, which sequentially includes a biaxial extruder, a casting machine, a pore former removing unit, a first stretching device, The second stretching device, heat treatment machine, coiler.
  • the pore-forming agent removal unit includes a tank body, a driving heat roller, a driven heat roller, and a pore-forming agent removal liquid; the tank body is a sealed tank body, and the polyolefin microporous sheet from the casting machine passes through the path. Designed for open sections.
  • the pore-forming agent removal liquid is located in the sealing tank; the position of the driving heat roller is higher than the liquid level of the pore-forming agent removal liquid; the driven heat roller is immersed in the pore-forming agent removal liquid. in liquid.
  • the second stretching device and the heat treatment machine are integrated together.
  • a specific embodiment of the present invention also provides a battery separator comprising any of the above-mentioned polyolefin microporous membranes.
  • the diaphragm is one of a ceramic coating diaphragm, a PVDF coating diaphragm, and an aramid coating diaphragm.
  • a specific embodiment of the present invention also provides an electrochemical device comprising any of the above-mentioned polyolefin microporous membranes or any of the battery separators as an element separating the positive and negative electrodes.
  • the specific embodiment of the present invention also provides a preparation method for preparing the polyolefin microporous membrane to be protected by the present invention, and the method comprises the following steps in turn:
  • the boiling pore former removal unit includes a tank body, a driving heat roller 1, a driven heat roller 2, and a pore former removal liquid 3; the driving heat roller 1 and the driven heat roller 2 can be heated at a temperature of 50 °C °C ⁇ 140°C; the residual rate of the pore-forming agent of the polyolefin microporous membrane is less than 0.05%, preferably less than 0.02%, more preferably less than 0.01%, and most preferably the residual amount of the pore-forming agent is 0.
  • the pore-forming agent accounts for 40-50% of the total mass of the polyolefin resin and the pore-forming agent, and the kinematic viscosity at 60° C. is 5-200 mm 2 /s.
  • the pore-forming agent used, as long as it can sufficiently dissolve the polyolefin, and the pore-forming agent can be, for example, but not limited to, one of liquid paraffin, mineral oil, and soybean oil. or more. Most preferably the pore former is liquid paraffin.
  • liquid paraffin can form a multi-layered oriented pore structure inside the porous substrate after being melt-kneaded and extracted with a polyolefin resin such as polyethylene resin, which greatly increases the successive pulling of the gelatinous membrane. stretch factor. The higher the draw ratio and the degree of crystallization, the higher the mechanical strength of the porous substrate. Therefore, as a pore former, liquid paraffin can improve the tensile strength and puncture strength of the porous film, so that the thinning of the porous film can be further realized.
  • a polyolefin resin such as polyethylene resin
  • the weight average molecular weight of the polyolefin resin is 4.0-8.0 ⁇ 10 6
  • the polyolefin resin accounts for 50-60% of the total mass of the polyolefin resin and the pore-forming agent.
  • polyolefin refers to a polymer obtained by the polymerization or copolymerization of one or more olefins, including but not limited to the polyolefin resin selected from polyethylene, polypropylene, polyisopropylene or polyolefin One or more of butenes. It is further preferred that the polyolefin resin is polyethylene.
  • the driving heat roller 1 and the driven heat roller 2 are heated by the hot oil flowing in the rollers.
  • the pore-forming agent removal solution 3 is an organic solvent that is mutually soluble with the pore-forming agent.
  • the pore former removal liquid is dichloromethane.
  • the groove body is a sealed groove body, and the passage path of the polyolefin microporous sheet coming out of the casting machine is designed as an open part.
  • the pore-forming agent removing liquid 3 is located in the sealing tank; the position of the driving heat roller 1 is higher than the liquid level of the pore-forming agent removing liquid 3; the driven heat roller 2 is immersed in the pore former removal solution 3.
  • the driving heat roller 1 and the driven heat roller 2 are heated to 50°C to 140°C.
  • the method for heating the rollers at 7 hours is the same, which belongs to the conventional technical means of those skilled in the art, and does not need to be described in detail here.
  • the polyolefin microporous sheet heated by the driven heat roller 1 and the driven heat roller 2 immersed in the pore former removing liquid 3 will heat the methylene chloride at a temperature of 0 to 10° C. to 30° C. under normal conditions. ⁇ 39.8°C.
  • the liquid molecules in the pore-forming agent removal liquid 3 gain more kinetic energy due to heat transfer and are very active.
  • the energy generated by these kinetic energy is enough to break free from the force between the liquid molecules, so its viscosity decreases; in addition , the increase in temperature makes the molecular motion or vibration speed up, so that the intermolecular repulsion increases.
  • the intermolecular distance will increase, and the gravitational and repulsive forces will decrease, so that the gravitational and repulsive forces will reach equilibrium again, thus causing the liquid surface tension. decline.
  • the pore-forming agent removal liquid 3 it will make it easier for the pore-forming agent removal liquid 3 to enter the micropores, improve the exchange rate, and increase the removal efficiency of the successful agent, and the residual rate of the pore-forming agent will be lower than 0.05%. Further, by adjusting the raw material formula of different porogen proportions, and different heating temperatures of the driving hot roller 1 and the driven hot roller 2, the removal efficiency of the successful agent is improved, and the residual rate of the porogen will be lower than 0.02% and lower than 0.01%. Even the residual amount of porogen is 0.
  • the stretching in step (4) is asynchronous biaxial stretching (MD+TD) or synchronous biaxial stretching (SBS).
  • the stretching in step (4) is asynchronous biaxial stretching
  • the success agent is removed by the pore former removing unit of the present invention
  • the roughness of the polyolefin sheet increases, so that the MD roll surface is stretched 6, the friction between the roller surface and the polyolefin sheet increases, and it is not easy to slip.
  • the cast sheet with higher molecular weight (4.0 ⁇ 8.0 ⁇ 10 6 ) and higher powder ratio (50% ⁇ 60%) of the present invention can be stretched firstly by 10 ⁇ 35 times along the MD direction, and then stretched along the TD direction. Extend 10 to 20 times. More preferably, the stretching ratio is 15 to 25 times in the MD direction, and then 10 to 15 times in the TD direction.
  • the stretching in step (4) is synchronous biaxial stretching
  • the success agent is removed by the pore former removing unit of the present invention
  • the roughness of the polyolefin sheet increases, so that the SBS clamp is stretched for 10
  • the friction force between the clamp and the polyolefin sheet increases, it is not easy to disengage the clamp.
  • the casting sheet of the present invention with higher molecular weight (4.0-8.0 ⁇ 10 6 ) and higher powder ratio (50%-60%) can be stretched by 10-20 times. More preferably, the draw ratio is 10 to 15 times.
  • step (5) the stretching ratio at which the base film is stretched again along at least one axial direction is 2-4 times.
  • the orientation of the final product separator is increased, so that its mechanical strength (tensile strength and needle punch strength) is greatly enhanced, and the slippage is avoided to cause microporous closed cells in the sheet.
  • the phenomenon of dislocation / hole dislocation there are many through holes, more lithium ion channels with high through rate are created, and the impedance of the separator is reduced.
  • Film thickness Use a Marr thickness tester to measure the width of the finished product at intervals of 10cm in the longitudinal direction, and then obtain the average film thickness;
  • Air permeability value At room temperature, use Wangyan type air permeability meter to set the time for 100cc gas to pass through the diaphragm, and measure the stable value after 5 seconds;
  • Porosity Take a 100mm ⁇ 100mm sample, weigh it with an electronic balance, and combine with the polyethylene density, and convert it according to the formula: (1-weight/sample area)/weight ⁇ 0.957 ⁇ 100%;
  • Tensile strength & elongation at break use electronic universal material testing machine XJ830, cutting sample size: 15mm ⁇ 20cm, 200mm/min travel speed for measurement;
  • Needle punch strength Use the electronic universal material testing machine XJ830, clamp the sample to be tested, and use the front end diameter of 1mm (0.5mmR) to measure at a travel speed of 50mm/min;
  • Thermal shrinkage rate Use the high temperature test box Espec SEG-021H to place the 100mm ⁇ 100mm microporous membrane at 110°C for 1 hour, and measure the length by the image measuring instrument XTY-5040, and count the lengths in the TD and MD directions before and after thermal drying, using the formula : (before heat treatment - after heat treatment)/before heat treatment ⁇ 100% conversion;
  • Kinematic viscosity use the Kinematic Viscometer DSY-004, set the measurement temperature to 60°C, and measure the kinematic viscosity after 1 hour of stabilization;
  • Residual oil rate Cut a 10mm ⁇ 10mm diaphragm sample, weigh it with an electronic balance, place pure water in an Ultrasonic Cleaner 1740T, and place a 500ml beaker with 300ml of pure dichloromethane, put in the sample, set the ultrasonic time to 60s, Then place it in a 105 °C oven to dry for 5 minutes, use an electronic balance to weigh the weight before and after cleaning, and use the formula: (weight before treatment - weight after treatment) / weight before treatment ⁇ 100% converted residual oil ratio;
  • Impedance Use the battery chamber sampler to add sample, add electrolyte to the 2/3 scale of the battery chamber, use the Agilent data acquisition instrument KEYSIGHT 34972A to select the resistance test channel, click Run, and wait for the device to automatically analyze the data.
  • Extraction was carried out in the methane tank to remove the pore-forming agent, and then 2 times secondary TD stretching was carried out at 120° C. to set the shape, and the film was wound with a winding roll to obtain a polyolefin microporous membrane with a thickness of 2 ⁇ m.
  • the mass percentage of 20% polyethylene (Mw is 3.5 ⁇ 10 6 ) and 80% white oil are put into the extruder at a flow rate of 600kg/h and extruded at 180°C and 80rpm. , extruded through a T-die head, and then formed into a cast sheet after being contacted and cooled by a cold roll with a temperature of 35 °C.
  • the cast sheet was stretched 9 times in the machine direction (MD) 6 at 110°C using a stretching machine, followed by 8 times stretching in the width direction (TD) 7 at 110°C, and then subjected to dichloride at 15°C.
  • the mass percentage of 20% polyethylene (Mw is 3.5 ⁇ 10 6 ) and 80% white oil are put into the extruder at a flow rate of 800kg/h and extruded at 180°C and 80rpm. , extruded through a T-die head, and then formed into a cast sheet after being contacted and cooled by a cold roll with a temperature of 35 °C.
  • the cast sheet was stretched 6 times in the machine direction (MD) 6 at 110°C using a stretching machine, followed by 8 times stretching in the width direction (TD) 7 at 110°C, and then subjected to dichloride at 15°C.
  • the polyolefin microporous films of the present invention all have excellent properties, and their thickness, tensile strength, puncture strength, air permeability, porosity and thermal shrinkage rate can all meet the requirements for the thickness and mechanical strength of the microporous film. It is very suitable for use in the field of power lithium-ion battery separators.
  • the polyolefin microporous membrane prepared by the method of the present invention can also be applied to various filtration membranes such as humidification membrane, water purification membrane, artificial dialysis membrane, nanofiltration membrane, ultrafiltration membrane, reverse osmosis membrane, etc., as well as cell reproduction substrates, etc. in the field.
  • various filtration membranes such as humidification membrane, water purification membrane, artificial dialysis membrane, nanofiltration membrane, ultrafiltration membrane, reverse osmosis membrane, etc., as well as cell reproduction substrates, etc. in the field.

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  • Chemical Kinetics & Catalysis (AREA)
  • Engineering & Computer Science (AREA)
  • Manufacturing & Machinery (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Medicinal Chemistry (AREA)
  • Health & Medical Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Cell Separators (AREA)
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Abstract

本发明涉及电池隔膜领域，具体公开了一种膜厚为2～30μm、穿刺强度为1000～2000gf、MD方向的拉伸强度为3200～5000kgf/cm 2、TD方向的拉伸强度为2800～4800kgf/cm 2、孔隙率为40％～57％、最大孔径33～48nm、气体渗透速率为10～400秒/100ml、阻抗为0.3～0.9Ω/cm 2的聚烯烃微多孔膜以及其生产系统、使用该基膜的涂覆隔膜和电化学装置。本发明聚烯烃微多孔膜均具有出色的性能，它们的厚度、拉伸强度、穿刺强度、透气性、孔隙率以及热收缩率均能满足对微多孔膜的厚度和机械强度有较高要求的应用，非常适合用于动力锂离子电池隔膜领域。

Description

一种聚烯烃微多孔膜及其生产系统、电池隔膜、电化学装置 技术领域
本发明涉及电池隔膜领域，具体涉及一种聚烯烃微多孔膜及其生产系统、电池隔膜、电化学装置。
背景技术
聚烯烃微多孔膜通常用于电池用隔膜、电解电容器用隔膜、超滤膜、微滤膜及医用膜等各种用途。无论是数码类锂离子电池还是动力类锂离子电池，在保证隔膜性能的基础上，轻薄化已成为趋势。聚烯烃微多孔膜的薄膜化，可以提高电极层的层叠数，有利于提高锂电池的能量密度和容量，从而使高输出化实现成为可能。但是，现有的超薄聚烯烃微多孔膜的缺点是强度较差，在其作为间隔件膜与电极一起高张力卷绕时，现有的超薄聚烯烃微多孔膜容易发生断裂。因此，现有技术仍然不能生产厚度均匀、质量稳定的超薄高强度隔膜。
在中国专利申请号CN 102136557 A中，公开了一种锂离子电池隔膜制备方法，该方法使用超高分子聚乙烯为主材料，制备了厚度达到20μm的强度好的隔膜。
在日本专利JPH0873643 A中，公开了一种锂离子电池隔膜制备方法，该方法使用粘均分子量10万以上的聚乙烯，制备了具有特定的厚度、透气性、孔隙率和拉伸伸长率的隔膜，该隔膜的厚度为20～40μm。
发明内容
上述专利和专利申请中公开的配方和方法解决了传统技术中薄膜强度的问题，但是还存在着下述缺陷，即隔膜厚度过厚的问题，不能达到超薄、高强度的要求。超薄高强度聚烯烃微多孔膜的技术难点在于超薄隔膜的厚度、强度和孔隙率等性能不能得到兼顾，且隔膜的厚度均匀性较差。
因此，本发明的目的是为了克服上述现有技术存在的缺陷而提供一种聚烯烃微多孔膜，该微多孔膜的孔隙率高、超薄、高强度且具有好的厚度均匀性，能够提高电池性能和降低电池成本。
为达到上述目的，本发明的技术方案是这样实现的：
本发明一个目的在于提供一种聚烯烃微多孔膜，其膜厚为2～30μm，穿刺强度为1000～2000gf。
进一步地，在MD方向的拉伸强度为3200～5000kgf/cm 2，在TD方向的拉伸强度为2800～4800kgf/cm 2。
进一步地，MD方向延伸率47～98％，TD方向延伸率63～110％。
进一步地，孔隙率为40％～57％，最大孔径33～48nm，气体渗透速率为10～400秒/100ml。
进一步地，阻抗为0.3～0.9Ω/cm 2。
进一步地，所述聚烯烃微多孔膜由重均分子量为4.0～8.0×10 6的聚乙烯组成。
本发明另一个目的在于提供一种生产上述任一种聚烯烃微多孔膜的系统，沿产线方向依次包括双轴挤出机，流延机，成孔剂去除单 元，第一拉伸装置，第二拉伸装置，热处理机，卷取机。
进一步地，所述成孔剂去除单元包括槽体、驱动热辊、从动热辊、成孔剂去除液；所述槽体为密封槽体，流延机出来的聚烯烃微多孔薄片经过路径为敞开部设计。
更进一步地，所述成孔剂去除液位于所述密封槽体内；所述驱动热辊位置高于所述成孔剂去除液液面；所述从动热辊浸没于所述成孔剂去除液中。
进一步地，所述第二拉伸装置和所述热处理机集成在一起。
本发明另一个目的在于提供一种电池隔膜，所述电池隔膜包含上述任一种聚烯烃微多孔膜。
进一步地，所述隔膜为陶瓷涂覆隔膜、PVDF涂覆隔膜、芳纶涂覆隔膜中的一种。
本发明再一个目的在于提供一种电化学装置，包含上述任一种聚烯烃微多孔膜或任一种电池隔膜作为将正负两极分开的元件。
本发明的有益效果在于与现有的微多孔膜相比，采用本发明方法制备的聚烯烃微多孔膜更能够满足对微多孔膜的厚度均匀性、超薄和高强度有较高要求的应用，特别适合用于动力锂离子电池隔膜领域。
附图说明
图1为本发明一种实施方式的成孔剂去除单元示意图；
图2为现有技术聚烯烃微多孔膜的制备工艺流程图；
图3为本发明一种实施方式的聚烯烃微多孔膜的制备工艺流程图；
图4为本发明另一种实施方式的聚烯烃微多孔膜的制备工艺流程图；
元件标号说明
1、驱动热辊
2、从动热辊
3、成孔剂去除液
4、挤出
5、冷却成片
6、MD拉伸
7、TD拉伸
8、成孔剂去除
9、TD二次拉伸
10、SBS拉伸。
具体实施方式
以下对本发明的具体实施方式结合附图进行详细说明。应当理解的是，此处所描述的具体实施方式仅用于说明和解释本发明，并不用于限制本发明。
本发明具体实施方式提供一种聚烯烃微多孔膜，其膜厚为2～30μm，穿刺强度为1000～2000gf。
进一步地，在MD方向的拉伸强度为3200～5000kgf/cm 2，在TD方向的拉伸强度为2800～4800kgf/cm 2。
进一步地，MD方向延伸率47～98％，TD方向延伸率63～110％。
进一步地，孔隙率为40％～57％，最大孔径33～48nm，气体渗透速率为10～400秒/100ml。
进一步地，阻抗为0.3～0.9Ω/cm 2。
进一步地，所述聚烯烃微多孔膜由重均分子量为4.0～8.0×10 6的聚乙烯组成。
本发明具体实施方式还提供一种生产上述任一种聚烯烃微多孔膜的系统，沿产线方向依次包括双轴挤出机，流延机，成孔剂去除单元，第一拉伸装置，第二拉伸装置，热处理机，卷取机。
进一步地，所述成孔剂去除单元包括槽体、驱动热辊、从动热辊、成孔剂去除液；所述槽体为密封槽体，流延机出来的聚烯烃微多孔薄片经过路径为敞开部设计。
更进一步地，所述成孔剂去除液位于所述密封槽体内；所述驱动热辊位置高于所述成孔剂去除液液面；所述从动热辊浸没于所述成孔剂去除液中。
进一步地，所述第二拉伸装置和所述热处理机集成在一起。
本发明具体实施方式还提供一种电池隔膜，所述电池隔膜包含上述任一种聚烯烃微多孔膜。
进一步地，所述隔膜为陶瓷涂覆隔膜、PVDF涂覆隔膜、芳纶涂覆隔膜中的一种。
本发明具体实施方式还提供一种电化学装置，包含上述任一种聚烯烃微多孔膜或任一种电池隔膜作为将正负两极分开的元件。
本发明具体实施方式还提供了一种制备本发明所要保护的聚烯 烃微多孔膜的制备方法，所述方法依次包括以下步骤：
(1)将聚烯烃树脂及成孔剂混合加热到熔融状的混炼溶液；
(2)将所述混炼溶液从模头挤出，并冷却形成含成孔剂的流延薄片；
(3)将所述流延薄片经过煮沸氏成孔剂去除单元，除去成孔剂；
(4)将除去成孔剂后的流延薄片至少沿一个轴向拉伸得到基膜；
(5)将所述基膜再次至少沿一个轴向进行拉伸定型，得到所述聚烯烃微多孔膜；
其中，所述煮沸氏成孔剂去除单元包括槽体、驱动热辊1、从动热辊2、成孔剂去除液3；所述驱动热辊1和从动热辊2可加热温度为50℃～140℃；所述聚烯烃微多孔膜的成孔剂残余率低于0.05％，优选低于0.02％，更优选低于0.01％，最优选成孔剂残余量为0。
进一步地，所述成孔剂占聚烯烃树脂和成孔剂总质量的40～50％，60℃下运动粘度为5～200mm 2/s。
在本申请中，对所采用的成孔剂没有特别限制，只要其能够充分地溶解聚烯烃就可以，所述成孔剂可以为例如但不限于液体石蜡、矿物油、大豆油中的一种或多种。最优选成孔剂为液体石蜡。
液体石蜡作为成孔剂，与聚烯烃树脂如聚乙烯树脂一起熔融混炼、萃取之后在多孔性基材的内部能够形成多层取向的气孔结构，大大地增大凝胶状膜片的逐次拉伸倍数。拉伸倍数和结晶化程度越高，多孔性基材的机械强度就越高。因此，液体石蜡作为成孔剂能够提高多孔性薄膜的拉伸强度和穿刺强度，使得多孔膜的薄膜化得到进一步 实现。
进一步地，所述聚烯烃树脂的重均分子量为4.0～8.0×10 6，所述聚烯烃树脂占聚烯烃树脂和成孔剂总质量的50～60％。
在本申请中，术语“聚烯烃”是指由一种或几种烯烃聚合或共聚制得的聚合物，包括但不限于所述聚烯烃树脂选自聚乙烯、聚丙烯、聚异丙烯或聚丁烯中的一种或多种。进一步优选所述聚烯烃树脂为聚乙烯。
进一步地，所述驱动热辊1和从动热辊2通过辊内流动的热油进行加热。
进一步地，所述成孔剂去除液3为与成孔剂互溶的有机溶剂。优选所述成孔剂去除液为二氯甲烷。
进一步地，所述槽体为密封槽体，流延机出来的聚烯烃微多孔薄片经过路径为敞开部设计。
如图1所示，进一步地，所述成孔剂去除液3位于所述密封槽体内；所述驱动热辊1位置高于所述成孔剂去除液3液面；所述从动热辊2浸没于所述成孔剂去除液3中。
通过导入导热油，使驱动热辊1和从动热辊2加热至50℃～140℃，这里，使驱动热辊1和从动热辊2加热的具体方法与常规MD、TD拉伸6、7时辊加热的方法一致，属于本领域技术人员的惯用技术手段，这里无需详细说明。此时，被驱动热辊1加热后的聚烯烃微多孔薄片和浸没于所述成孔剂去除液3中的从动热辊2将使常态下0～10℃的二氯甲烷加热至30℃～39.8℃。
成孔剂去除液3中液体分子在加热的过程中，由热量传递而获得了更大的动能，非常活跃，这些动能产生的能量足以挣脱液体分子之间的作用力，因此其粘度下降；此外，温度升高使分子运动或者说振动加快，从而分子间斥力上升，为了再次达到平衡，分子间距离会增大，引力和斥力都减小，使得引力和斥力再次达到平衡，从而引起液体表面张力下降。因此，将使成孔剂去除液3更易进入微多孔，提升交换率，增加去除成功剂效率，成孔剂残余率将低于0.05％。进一步通过调配不同的成孔剂占比原料配方，不同的驱动热辊1和从动热辊2加热温度，提升去除成功剂效率，成孔剂残余率将低于0.02％，低于0.01％，乃至成孔剂残余量为0。
进一步地，步骤(4)中的所述拉伸为异步双向拉伸(MD+TD)或同步双向拉伸(SBS)。
如图3所示，当步骤(4)中的所述拉伸为异步双向拉伸时，采用本发明成孔剂去除单元去除成功剂后，聚烯烃薄片粗糙度增加，使得MD辊面拉伸6时，辊面与聚烯烃薄片摩擦力增加，不易打滑。从而可以实现本发明更高分子量(4.0～8.0×10 6)、更高粉料比(50％～60％)配方的流延薄片先沿MD方向拉伸10～35倍，后沿TD方向拉伸10～20倍。进一步优选拉伸倍数为先沿MD方向拉伸15～25倍，后沿TD方向拉伸10～15倍。
如图4所示，当步骤(4)中的所述拉伸为同步双向拉伸时，采用本发明成孔剂去除单元去除成功剂后，聚烯烃薄片粗糙度增加，使得SBS夹具拉伸10时，夹具与聚烯烃薄片摩擦力增加，不易脱夹。从而 可以实现本发明更高分子量(4.0～8.0×10 6)、更高粉料比(50％～60％)配方的流延薄片拉伸10～20倍。进一步优选拉伸倍数为10～15倍。
进一步地，步骤(5)中所述基膜再次至少沿一个轴向进行拉伸的拉伸倍率为2～4倍。
通过上述不同方法的大倍率的拉伸后，最终产品隔膜的取向性增加，从而其机械强度(拉伸强度和针刺强度)得到了大幅度增强，且避免打滑导致薄片出现多微孔闭孔/孔错位现象，直通孔多，创造更多直通率高的锂离子通道，隔膜的阻抗降低。
以下将通过实施例对本发明进行详细描述。
在以下实施例和对比例中，膜性能测试均按照下述方法执行：
膜厚：用马尔厚度测试仪沿纵向以10cm的间隔在成品宽度范围内进行测定，然后得出膜厚平均值；
透气值：在室温下，使用王研式透气仪设置100cc气体通过隔膜时间，稳定测量5秒后的稳定数值；
孔隙率：截取100mm×100mm样片，使用电子天枰称重，并结合聚乙烯密度，根据公式：(1-重量/样片面积)/重量×0.957×100％折算；
最大孔径：使用窄孔径测试仪，使用氮气通过泡点法测量；
拉伸强度&断裂伸长率：使用电子万能材料试验机XJ830，裁样规格：15mm×20cm，200mm/min行进速度进行测量；
针刺强度：使用电子万能材料试验机XJ830，夹住需测试样品，使用前端直径1mm(0.5mmR)以50mm/min行进速度进行测量；
热收缩率：使用高温试验箱Espec SEG-021H将100mm×100mm微多孔膜在110℃下放置1h，并通过影像测量仪XTY-5040进行长度测量，统计热烘前后TD与MD方向长度，使用公式：(热处理前-热处理后)/热处理前×100％折算；
运动粘度：使用运动粘度测定仪DSY-004，设定测量温度为60℃，稳定1h后进行运动粘度测量；
残油率：裁10mm×10mm隔膜样片，使用电子天平称重，在Ultrasonic Cleaner 1740T中，放置纯水，并放置500ml烧杯中带300ml纯二氯甲烷，放入样片，设定超声时间为60s，后放置在105℃烘箱中干燥5min，使用电子天平称量清洗前后的重量，使用公式：(处理前重量-处理后重量)/处理前重量×100％折算残油率；
阻抗：使用电池室加样器加样，加注电解液至电池室2/3刻度，使用安捷伦数据采集仪KEYSIGHT 34972A选择电阻测试通道，点击运行，等待设备自动分析数据。
实施例1
首先，将质量百分比为50％聚乙烯(Mw为8.0×10 6)和50％白油按500kg/h的流量投入到挤出机中挤出，在220℃、100rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形成流延薄片。然后进入成孔剂去除单元，通过导热油将驱动热辊1、从动热辊2加热至140℃，进而槽体中二氯甲烷被升温至39.8℃，进行成孔剂去除工序。将成孔剂去除后的流延薄片使用拉伸机在120℃下沿机械方向(MD)6进行10倍拉伸，接着在100℃下沿宽度方向(TD)7进行10倍拉伸，后在120℃下进行2倍二次TD拉伸9定 型，用卷取辊进行卷取，得到厚度为30μm的聚烯烃微多孔膜。
实施例2
首先，将质量百分比为55％聚乙烯(Mw为6.0×10 6)和45％白油按650kg/h的流量投入到挤出机中挤出，在220℃、100rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形成流延薄片。然后进入成孔剂去除单元，通过导热油将驱动热辊1、从动热辊2加热至100℃，进而槽体中二氯甲烷被升温至35℃，进行成孔剂去除工序。将成孔剂去除后的流延薄片使用拉伸机在120℃下沿机械方向(MD)6进行20倍拉伸，接着在100℃下沿宽度方向(TD)7进行15倍拉伸，后在120℃下进行2倍二次TD拉伸9定型，用卷取辊进行卷取，得到厚度为14μm的聚烯烃微多孔膜。
实施例3
首先，将质量百分比为55％聚乙烯(Mw为6.0×10 6)和45％白油按400kg/h的流量投入到挤出机中挤出，在220℃、100rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形成流延薄片。然后进入成孔剂去除单元，通过导热油将驱动热辊1、从动热辊2加热至100℃，进而槽体中二氯甲烷被升温至35℃，进行成孔剂去除工序。将成孔剂去除后的流延薄片使用拉伸机在120℃下沿机械方向(MD)6进行20倍拉伸，接着在100℃下沿宽度方向(TD)7进行15倍拉伸，后在120℃下进行2倍二次TD拉伸9定型，用卷取辊进行卷取，得到厚度为9μm的聚烯烃微多孔膜。
实施例4
首先，将质量百分比为55％聚乙烯(Mw为6.0×10 6)和45％白油按300kg/h的流量投入到挤出机中挤出，在220℃、100rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形 成流延薄片。然后进入成孔剂去除单元，通过导热油将驱动热辊1、从动热辊2加热至100℃，进而槽体中二氯甲烷被升温至35℃，进行成孔剂去除工序。将成孔剂去除后的流延薄片使用拉伸机在120℃下沿机械方向(MD)6进行20倍拉伸，接着在100℃下沿宽度方向(TD)7进行15倍拉伸，后在120℃下进行2倍二次TD拉伸9定型，用卷取辊进行卷取，得到厚度为7μm的聚烯烃微多孔膜。
实施例5
首先，将质量百分比为60％聚乙烯(Mw为4.0×10 6)和40％白油按500kg/h的流量投入到挤出机中挤出，在220℃、100rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形成流延薄片。然后进入成孔剂去除单元，通过导热油将驱动热辊1、从动热辊2加热至50℃，进而槽体中二氯甲烷被升温至30℃，进行成孔剂去除工序。将成孔剂去除后的流延薄片使用拉伸机在120℃下沿机械方向(MD)6进行35倍拉伸，接着在100℃下沿宽度方向(TD)7进行20倍拉伸，后在120℃下进行2倍二次TD拉伸9定型，用卷取辊进行卷取，得到厚度为2μm的聚烯烃微多孔膜。
对比例1
使用传统的工艺方法，首先将质量百分比为20％聚乙烯(Mw为3.5×10 6)和80％白油按90kg/h的流量投入到挤出机中挤出，在180℃、80rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形成流延薄片。将流延薄片使用拉伸机在110℃下沿机械方向(MD)6进行9倍拉伸，接着在110℃下沿宽度方向(TD)7进行8倍拉伸，再经过15℃的二氯甲烷槽体中进行萃取去除成孔剂，后在120℃下进行2倍二次TD拉伸9定型，用卷取辊进行卷取，得到厚度为2μm的聚烯烃微多孔膜。
对比例2
使用传统的工艺方法，首先将质量百分比为20％聚乙烯(Mw为3.5×10 6)和80％白油按300kg/h的流量投入到挤出机中挤出，在180℃、80rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形成流延薄片。将流延薄片使用拉伸机在110℃下沿机械方向(MD)6进行9倍拉伸，接着在110℃下沿宽度方向(TD)7进行8倍拉伸，再经过15℃的二氯甲烷槽体中进行萃取去除成孔剂，后在120℃下进行2倍二次TD拉伸9定型，用卷取辊进行卷取，得到厚度为7μm的聚烯烃微多孔膜。
对比例3
使用传统的工艺方法，首先将质量百分比为20％聚乙烯(Mw为3.5×10 6)和80％白油按380kg/h的流量投入到挤出机中挤出，在180℃、80rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形成流延薄片。将流延薄片使用拉伸机在110℃下沿机械方向(MD)6进行9倍拉伸，接着在110℃下沿宽度方向(TD)7进行8倍拉伸，再经过15℃的二氯甲烷槽体中进行萃取去除成孔剂，后在120℃下进行2倍二次TD拉伸9定型，用卷取辊进行卷取，得到厚度为9μm的聚烯烃微多孔膜。
对比例4
使用传统的工艺方法将，质量百分比为20％聚乙烯(Mw为3.5×10 6)和80％白油按600kg/h的流量投入到挤出机中挤出，在180℃、80rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形成流延薄片。将流延薄片使用拉伸机在110℃下沿机械方向(MD)6进行9倍拉伸，接着在110℃下沿宽度方向(TD)7进行8倍拉伸，再经过15℃的二氯甲烷槽体中进行萃取去除成孔 剂，后在120℃下进行2倍二次TD拉伸9定型，用卷取辊进行卷取，得到厚度为14μm的聚烯烃微多孔膜。
对比例5
使用传统的工艺方法将，质量百分比为20％聚乙烯(Mw为3.5×10 6)和80％白油按800kg/h的流量投入到挤出机中挤出，在180℃、80rpm的条件下，经过T型模头挤出，在受到温度为35℃的冷辊接触冷却后，形成流延薄片。将流延薄片使用拉伸机在110℃下沿机械方向(MD)6进行6倍拉伸，接着在110℃下沿宽度方向(TD)7进行8倍拉伸，再经过15℃的二氯甲烷槽体中进行萃取去除成孔剂，后在120℃下进行2倍二次TD拉伸9定型，用卷取辊进行卷取，得到厚度为30μm的聚烯烃微多孔膜。
将实施例1～5和对比例1～5的隔膜性能测试结果如表1。
表1实施例与对比例隔膜性能对比表
Figure PCTCN2021118236-appb-000001
Figure PCTCN2021118236-appb-000002
将实施例1～5与对比例1～5比较，可见本发明聚烯烃微多孔膜透气性相差不大，但孔隙率、热收缩率较优，穿刺强度、拉伸强度性能得到明显大幅度的增强，阻抗大大降低。
本发明聚烯烃微多孔膜均具有出色的性能，它们的厚度、拉伸强度、穿刺强度、透气性、孔隙率以及热收缩率均能满足对微多孔膜的厚度和机械强度有较高要求的应用，非常适合用于动力锂离子电池隔膜领域。
采用本发明的方法制备的聚烯烃微多孔膜还可以适用于加湿膜、水净化膜、人工透析膜、纳滤膜、超滤膜、反渗透膜等过滤膜，及细胞繁殖基材等各种领域中。
以上涉及到公知常识的内容不作详细描述(如通过投料量调控隔膜产品的厚度是本领域的常规操作)，本领域的技术人员能够理解。
以上所述实施例仅示例性说明本发明的原理及其功效，而非用于限制本发明。任何熟悉此技术的人士皆可在不违背本发明的精神及范畴下，对上述实施例进行修饰或改变。因此，举凡所属技术领域中具有通常知识者在未脱离本发明所揭示的精神与技术思想下所完成的一切等效修饰或改变，仍应由本发明的权利要求所涵盖。

Claims (13)

  1. 一种聚烯烃微多孔膜，其特征在于：其膜厚为2～30μm，穿刺强度为1000～2000gf。
  2. 根据权利要求1所述的聚烯烃微多孔膜，其特征在于：在MD方向的拉伸强度为3200～5000kgf/cm 2，在TD方向的拉伸强度为2800～4800kgf/cm 2。
  3. 根据权利要求1所述的聚烯烃微多孔膜，其特征在于：MD方向延伸率47～98％，TD方向延伸率63～110％。
  4. 根据权利要求1所述的聚烯烃微多孔膜，其特征在于：孔隙率为40％～57％，最大孔径33～48nm，气体渗透速率为10～400秒/100ml。
  5. 根据权利要求1所述的聚烯烃微多孔膜，其特征在于：阻抗为0.3～0.9Ω/cm 2。
  6. 根据权利要求1所述的聚烯烃微多孔膜，其特征在于：所述聚烯烃微多孔膜由重均分子量为4.0～8.0×10 6的聚乙烯组成。
  7. 一种生产权利要求1～6中任一项所述聚烯烃微多孔膜的系统，其特征在于：沿产线方向依次包括双轴挤出机，流延机，成孔剂去除单元，第一拉伸装置，第二拉伸装置，热处理机，卷取机。
  8. 根据权利要求7所述的聚烯烃微多孔膜的生产系统，其特征在于：所述成孔剂去除单元包括槽体、驱动热辊、从动热辊、成孔剂去除液；所述槽体为密封槽体，流延机出来的聚烯烃微多孔薄片经过路径为敞开部设计。
  9. 根据权利要求8所述的聚烯烃微多孔膜的生产系统，其特征在于：所述成孔剂去除液位于所述密封槽体内；所述驱动热辊位置高于所述成孔剂去除液液面；所述从动热辊浸没于所述成孔剂去除液中。
  10. 根据权利要求7所述的聚烯烃微多孔膜的生产系统，其特征在于：所述第二拉伸装置和所述热处理机集成在一起。
  11. 一种电池隔膜，其特征在于：所述电池隔膜包含权利要求1～6中任一项所述的聚烯烃微多孔膜。
  12. 根据权利要求11所述的电池隔膜，其特征在于：所述隔膜为陶瓷涂覆隔膜、PVDF涂覆隔膜、芳纶涂覆隔膜中的一种。
  13. 一种电化学装置，其特征在于：包含权利要求1～6中任一项所述的聚烯烃微多孔膜或权利要求11或12所述的电池隔膜作为将正负两极分开的元件。
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