WO2019065073A1 - Membrane microporeuse constituée de polyoléfine, séparateur de batterie et batterie secondaire - Google Patents

Membrane microporeuse constituée de polyoléfine, séparateur de batterie et batterie secondaire Download PDF

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Publication number
WO2019065073A1
WO2019065073A1 PCT/JP2018/032273 JP2018032273W WO2019065073A1 WO 2019065073 A1 WO2019065073 A1 WO 2019065073A1 JP 2018032273 W JP2018032273 W JP 2018032273W WO 2019065073 A1 WO2019065073 A1 WO 2019065073A1
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WIPO (PCT)
Prior art keywords
polyolefin
less
microporous
microporous film
stretching
Prior art date
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Ceased
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PCT/JP2018/032273
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English (en)
Japanese (ja)
Inventor
遼 下川床
豊田　直樹
石原　毅
久万　琢也
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Toray Industries Inc
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Toray Industries Inc
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Publication date
Application filed by Toray Industries Inc filed Critical Toray Industries Inc
Priority to JP2018552017A priority Critical patent/JP7283080B2/ja
Priority to KR1020207005414A priority patent/KR102622533B1/ko
Priority to CN201880052513.3A priority patent/CN111032758A/zh
Publication of WO2019065073A1 publication Critical patent/WO2019065073A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • 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
    • 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
    • H01M10/00—Secondary cells; Manufacture thereof
    • H01M10/05—Accumulators with non-aqueous electrolyte
    • H01M10/052—Li-accumulators
    • 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
    • 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
    • H01M50/489—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
    • 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 present invention relates to a polyolefin microporous film, a battery separator, and a secondary battery which are suitably used as a separator of a secondary battery, a coated separator substrate, and the like.
  • lithium ion secondary batteries higher capacity and higher output are required. Furthermore, since it is suitable to shorten the distance between the electrodes in order to promote the increase in capacity and the increase in output, thinning of the lithium ion secondary battery separator is in progress. With the thinning of the separator, high mechanical strength is required in order to prevent local short circuit due to rupture of the membrane due to foreign substances in the battery manufacturing process and shortening of the distance between the electrodes. Furthermore, with the advancement of performance of secondary batteries, safety at the time of battery runaway due to overcharge or external impact is also required at a high level, and thermal runaway temperature is used to prevent short-circuiting of electrodes in the separator.
  • Patent Document 1 relates to a microporous film excellent in mechanical strength and heat shrinkage characteristics in the film width direction (hereinafter referred to as TD), which comprises modifying a stretching method using a polyolefin having a viscosity average molecular weight of 150,000 to 1,000,000.
  • TD film width direction
  • Technology is disclosed. However, as far as the manufacturing method is seen, it suppresses thermal contraction in one direction only for TD, and when a thermal runaway occurs due to a foreign object sticking from the outside of the battery, the contraction of the other can not be suppressed, and there is a concern that a short circuit may occur.
  • Patent Document 2 and Patent Document 3 many proposals have been made to add a crystal nucleating agent in order to increase the strength of the microporous film.
  • the microporous film to which the crystal nucleating agent is added is effective in enhancing the strength and enhancing the withstand voltage characteristics, but when the heat shrinkage, particularly the coexistence with the melting heat shrinkage characteristics under high temperature is insufficient
  • the object of the present invention is to solve the above-mentioned problems of the prior art, and to provide a polyolefin microporous film excellent in mechanical strength such as piercing strength and shape retention characteristics at high temperature, and having high uniformity and safety. It is to do.
  • the microporous polyolefin membrane according to the embodiment of the present invention is a microporous polyolefin membrane by adjusting the content of the polyolefin having a weight average molecular weight of 1.0 ⁇ 10 6 or more in the microporous polyolefin membrane to a certain range of content.
  • the melt shrinkage stress of the film can be suppressed. Furthermore, by speeding up the crystallization rate of the polyolefin composition by the addition of a crystal nucleating agent or the like, it is possible to efficiently propagate stress during stretching by refining and homogenizing the crystal structure and higher order structure. .
  • the microporous polyolefin membrane promotes structural change to crystals that greatly affects mechanical strength by stretching under specific conditions described later, and has excellent mechanical strength, shape retention characteristics at high temperature, and structural uniformity. Have.
  • the present invention adopts the following configuration in order to solve the problems as described above. That is, (1)
  • the half-crystallization time T 1/2 at 126 ° C. is 200 seconds or less, and the 50% porosity and the pin puncture strength at a film thickness of 20 ⁇ m are 6.0 N / 20 ⁇ m or more; when the MD direction P MD, the TD direction and P TD, at least one of not more than 0.8 MPa, polyolefin that P MD + TD is the sum of P MD and P TD is equal to or less than 1.5MPa Microporous membrane.
  • the microporous polyolefin film according to any one of the above (1) to (5) which is mainly composed of polyethylene.
  • the polyolefin microporous film according to any one of the above (1) to (6) which has an air permeation resistance of 50 to 600 sec / 100 cc in terms of a film thickness of 20 ⁇ m.
  • the polyolefin microporous film according to any one of the above (1) to (7) which contains a crystal nucleating agent.
  • the content ratio of polyethylene having a weight average molecular weight of 1.0 ⁇ 10 6 or more in the microporous polyolefin membrane is 25% by mass or less, according to any one of the above (1) to (8) Polyolefin microporous membrane.
  • a battery separator comprising the microporous polyolefin membrane of any one of (1) to (9).
  • a polyolefin microporous film according to an embodiment of the present invention has mechanical properties such as piercing strength while maintaining basic performance as a separator for a lithium ion secondary battery as compared to a conventional polyolefin microporous film. It becomes a microporous film excellent in strength, shape retention characteristics under high temperature, and uniformity of pore structure. As a result, it can be expected that the battery capacity can be improved by thinning as compared with the conventional microporous polyolefin membrane, and the possibility of short circuiting is reduced due to the high strength and the improvement of the shape retention characteristics at high temperature, It can be expected to improve battery safety as well.
  • the polyolefin microporous film according to the embodiment of the present invention has a half-crystallization time T 1/2 of 126 ° C. of 200 seconds or less, a 50% porosity and a piercing strength of 6.0 N / 20 ⁇ m at a film thickness of 20 ⁇ m. not less than, MD direction P MD molten thermal shrinkage stress, at least one of when the TD direction was set to P TD is less than or equal to 0.8 MPa, P MD + TD is the sum of P MD and P TD is less than or equal to 1.5MPa is there.
  • the half-crystallization time T 1/2 at 126 ° C. exceeds 200 seconds, the crystal structure becomes nonuniform during crystallization and the efficiency of stress dispersion with respect to the load on the microporous polyolefin membrane decreases, so the mechanical strength increases. It tends to be a low polyolefin microporous membrane.
  • the lower limit of the 126 ° C. half-crystallization time T 1/2 is not particularly limited, but is preferably 1 second or more, and more preferably 10 seconds or more. In order for the half-crystallization time T 1/2 at 126 ° C.
  • the 126 ° C. half crystallization time T 1/2 can be controlled by the addition of a crystal nucleating agent and the like, and the details of the control method will be described later.
  • a polyolefin microporous film (hereinafter sometimes referred to as a microporous film) according to an embodiment of the present invention has a 50% porosity and a piercing strength in terms of a film thickness of 20 ⁇ m of 6.0 N / 20 ⁇ m or more . More preferably, it is 6.5 N / 20 ⁇ m or more, still more preferably 7.0 N or more, and most preferably 7.5 N / 20 ⁇ m or more.
  • the puncture strength at 50% porosity and film thickness conversion of 20 ⁇ m refers to the puncture strength when the film thickness of the polyolefin microporous film having a porosity of 50% of the polyolefin microporous film is converted to 20 ⁇ m.
  • the puncture strength at 50% porosity and film thickness of 20 ⁇ m is considered to be higher if higher, but the upper limit of the microporous membrane according to the embodiment of the present invention is 30 N in consideration of the limit strength of the microporous membrane made of polyolefin. It is / 20 ⁇ m.
  • the 50% porosity and puncture strength at a film thickness of 20 ⁇ m of the microporous polyolefin film according to the embodiment of the present invention controls the crystallization rate of the polyolefin mixture by adding a crystal nucleating agent, etc., to refine the crystals.
  • the crystal structure can be adjusted by controlling the crystal structure depending on the temperature and the stretching conditions. Details of the control method will be described later.
  • the polyolefin microporous film according to the embodiment of the present invention has at least one direction (P MD ), where P MD is the MD direction (winding direction) of melting heat shrinkage stress and P TD is the TD direction (winding width direction). And P TD ) is 0.8 MPa or less. More preferably, it is 0.75 MPa or less, more preferably, 0.7 MPa or less, still more preferably, 0.5 MPa or less, and still more preferably, 0.4 MPa or less. When P MD and P TD are both greater than 0.8 MPa, undesirably can cause short-circuiting due to shrinkage during battery high temperature increases.
  • melt thermal shrinkage stress P MD and P TD is good more A low, in order to below 0.1MPa is excessively or narrow Makuhaba, it is necessary to drop the film forming speed by the stress relaxation mechanism Since the productivity may decrease, it is not preferable, and 0.1 MPa or more is preferable.
  • Melt thermal shrinkage stress P MD and P TD of the polyolefin microporous film according to the embodiment of the present invention the molecular weight and the stretching temperature and conditions of the polyolefin mixture may be adjusted. Details of the control method will be described later.
  • PMD + TD which is the sum of MD and TD directions of melt thermal shrinkage stress, is considered better if it is low, but in order to be less than 0.2 MPa, productivity may be reduced as described above Therefore, it is not preferable, and 0.2 MPa or more is preferable.
  • PMD + TD of the microporous polyolefin membrane according to the embodiment of the present invention can be adjusted by the molecular weight of the polyolefin mixture and the temperature and conditions of stretching. Details of the control method will be described later.
  • the microporous polyolefin membrane according to the embodiment of the present invention preferably has a maximum pore diameter of 45 nm or less as observed by a porometer.
  • the maximum pore size is more preferably 42 nm or less, still more preferably 40 nm or less. If the maximum pore size exceeds 45 nm, the possibility of heterogeneity of the cell reaction and growth of dendritic will increase, which is not preferable. If the maximum pore size is less than 10 nm, the air resistance will be extremely high, which may adversely affect the output of the battery, so it is preferably 10 nm or more.
  • the maximum pore size of the polyolefin microporous film according to the embodiment of the present invention controls the crystallization rate of the polyolefin mixture by addition of a crystal nucleating agent and the like to refine the crystal, or the crystal structure depending on temperature and stretching conditions. Can be adjusted by controlling Details of the control method will be described later.
  • the polyolefin microporous film according to the embodiment of the present invention preferably has an average flow pore size / maximum pore size ratio of 0.6 or more as observed from a porometer.
  • the ratio of the mean flow pore size / maximum pore size is more preferably 0.65 or more, still more preferably 0.67 or more, still more preferably 0.7 or more, and still more preferably 0.73 or more.
  • the value of the average flow pore size / maximum pore size is less than 0.6, coarse pores tend to be present in the inside of the microporous membrane, which may result in a decrease in voltage resistance characteristics or nonuniformity of the battery reaction. Not desirable.
  • the ratio of average flow pore size / maximum pore size is preferably as large as possible from the viewpoint of uniformity, but to make it larger than 0.9, it is necessary to add a crystal nucleating agent etc. in excess, and as a result, film physical properties and productivity Is not preferable, and is preferably 0.9 or less.
  • the ratio of the average flow pore size / maximum pore size of the polyolefin microporous film according to the embodiment of the present invention controls the crystallization rate of the polyolefin mixture by addition of a crystal nucleating agent, etc. to refine the crystal, temperature and stretching. The conditions can be adjusted by controlling the crystal structure. Details of the control method will be described later.
  • the area ratio of the melting peak at 141 ° C. or higher observed by DSC is preferably 25% or more.
  • the area ratio of the melting peak at 141 ° C. or more is more preferably 30% or more, still more preferably 33% or more, and particularly preferably 35% or more. If the area ratio of the melting peak at 141 ° C. or higher is less than 25%, the strength of the crystal structure is insufficient, and the strength of the microporous film is unfavorably lowered.
  • the area ratio of the melting peak of 141 ° C. or more exceeds 70%, the crystalline component with a low melting point decreases, and the shutdown characteristics may be deteriorated.
  • the area ratio of the melting peak of 141 ° C. or more of the polyolefin microporous film according to the embodiment of the present invention controls the crystallization rate of the polyolefin mixture by addition of a crystal nucleating agent, etc., to refine the crystals, and
  • the crystal structure can be adjusted by controlling the crystal structure according to the stretching conditions. Details of the control method will be described later.
  • the microporous polyolefin membrane according to the embodiment of the present invention preferably has a porosity of 30% or more.
  • the porosity is more preferably 40% or more, still more preferably 43% or more, and particularly preferably 45% or more.
  • the upper limit of the porosity of the polyolefin microporous film is preferably 70% or less, more preferably 60% or less, from the viewpoint of improving the film strength and the voltage resistance characteristics. If the porosity is less than 30%, the content of the electrolyte and the output of the secondary battery may be reduced, which is not preferable.
  • the porosity of the polyolefin microporous film according to the embodiment of the present invention controls the crystallization rate of the polyolefin mixture by addition of a crystal nucleating agent and the like to make the crystal finer, and the crystal and the temperature and stretching conditions. It can be adjusted by controlling the structure. Details of the control method will be described later.
  • the polyolefin microporous film according to the embodiment of the present invention preferably has an MD + TD tensile breaking strength of 350 MPa or more. More preferably, it is 370 MPa or more, still more preferably 400 MPa or more.
  • the MD + TD tensile strength at break is considered to be as high as possible, but in consideration of the basic performance of the microporous membrane made of polyolefin, the upper limit value of the microporous membrane according to the embodiment of the present invention is 800 MPa or less.
  • MD + TD tensile strength at break is less than 350 MPa, it can not withstand tensile stress due to coating or winding in a battery production process, compression in the width direction, and yield of production such as cracking or film breakage is likely to occur. Absent.
  • the MD + TD tensile breaking strength of the microporous polyolefin membrane according to the embodiment of the present invention controls the crystallization rate of the polyolefin mixture by addition of a crystal nucleating agent and the like to refine the crystal, temperature, and stretching conditions. It can be adjusted by controlling the crystal structure. Details of the control method will be described later.
  • the microporous polyolefin membrane according to the embodiment of the present invention preferably has an air resistance of 50 to 600 sec / 100 cc when converted to a film thickness of 20 ⁇ m.
  • the air resistance as converted to a film thickness of 20 ⁇ m is more preferably 50 to 400 sec / 100 cc, still more preferably 50 to 300 sec / 100 cc, and particularly preferably 50 to 250 sec / 100 cc.
  • a sufficient ion permeability can be obtained if the gas-passage resistance at a film thickness of 20 ⁇ m conversion is 600 sec / 100 cc or less, which is preferable because the electric resistance is reduced.
  • the air permeability when converted to a film thickness of 20 ⁇ m is 50 sec / 100 cc or more, because the ion permeability is excellent and the possibility of internal short circuit is reduced.
  • the gas permeation resistance of the microporous polyolefin membrane according to the embodiment of the present invention when converted to a film thickness of 20 ⁇ m controls crystallization speed by addition of a crystal nucleating agent of a polyolefin mixture, etc., to refine crystals, It can adjust with temperature, extending
  • the thickness of the microporous polyolefin membrane according to the embodiment of the present invention is preferably 1 to 2000 ⁇ m, more preferably 1 to 1000 ⁇ m.
  • the solid thermal contraction rate of MD and TD of the microporous polyolefin membrane according to the embodiment of the present invention is preferably 30% or less, more preferably 20% or less, and still more preferably 15% or less. If the microporous film is used as a lithium battery separator if the individual heat shrinkage ratio of MD and TD is 30% or less, the separator end does not shrink even if heat is generated, and the possibility of occurrence of a short circuit can be reduced. .
  • the lower limit of the solid thermal contraction rate is not particularly limited, but is preferably 0% or more (not expanded) because defects such as wrinkles can be prevented during heating in the coating step.
  • the content ratio of polyethylene having a weight average molecular weight (Mw) of 1.0 ⁇ 10 6 or more in the microporous polyolefin membrane according to the embodiment of the present invention is preferably 25% by mass or less, more preferably 1 to 20% by mass It is more preferably 1 to 15% by mass, and most preferably 5 to 10% by mass.
  • Mw weight average molecular weight
  • the content ratio of polyethylene having a weight average molecular weight of 1.0 ⁇ 10 6 or more is less than 1% by mass, mechanical strength such as puncture strength and tensile strength at break of the microporous membrane may be lowered.
  • the content ratio of polyethylene having a weight average molecular weight of 1.0 ⁇ 10 6 or more is included in the above range, a microporous film having high strength and excellent melt heat shrinkage stress can be obtained without impairing the productivity of the microporous polyolefin film. You can get it.
  • the microporous polyolefin membrane according to the embodiment of the present invention is composed of a mixture containing a polyolefin resin as a main component.
  • the main component in the present application is that the content of the polyolefin resin is 50% by mass or more. And preferably 70% by mass or more, more preferably 80% by mass or more, particularly preferably 90% by mass or more.
  • the present invention will be described item by item.
  • examples include ethylene, polyvinylidene fluoride, polyvinylidene chloride, polyvinyl fluoride, polyvinyl chloride, polysulfone and polycarbonate.
  • the polyolefin resin may be a mixture of two or more polyolefins.
  • the polyolefin resin preferably contains a polyethylene resin.
  • the content of the polyethylene resin in the polyolefin resin is preferably 90% by mass or more, more preferably 95% by mass or more, and particularly preferably 99% by mass or more.
  • the ratio of the polyethylene resin in the polyolefin resin is in the above range, the strength of the resulting microporous polyolefin membrane can be improved.
  • the polyethylene resin (I) ethylene homopolymer, or (II) copolymers of ethylene and comonomers such as propylene, butene-1, hexene-1 and the like and mixtures thereof can be used.
  • ethylene homopolymer is preferable from the viewpoint of economy and film strength, and high-density polyethylene having a weight average molecular weight (Mw) of 1 ⁇ 10 4 or more and less than 1 ⁇ 10 6 is preferable.
  • MwD weight average molecular weight dispersion
  • the molecular weight dispersion (MwD) of the polyethylene resin is, for example, preferably 1 to 20, and more preferably 3 to 10, from the viewpoint of extrusion moldability and physical property control by stable crystallization control.
  • the content of comonomers in the copolymer as polyethylene resin is preferably 10 mol% or less based on 100 mol% of the copolymer.
  • Such copolymers can be made by any convenient polymerization process, such as processes using Ziegler-Natta catalysts or single site catalysts.
  • the co-monomer may be a ⁇ ⁇ ⁇ ⁇ ⁇ -olefin, for example, if desired, the co-monomer is propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene-1, vinyl acetate, methyl methacrylate , Styrene, or one or more of the other monomers.
  • an ultrahigh molecular weight polyethylene having a weight average molecular weight (Mw) of 1.0 ⁇ 10 6 or more may be contained in the polyolefin resin at 25% by mass or less, more preferably 20% by mass or less, more preferably Is 15% by weight or less, and most preferably 10% by weight or less.
  • Mw weight average molecular weight
  • the mechanical strength such as the puncture strength and the tensile breaking strength of the microporous film is increased while the melting heat shrinkage Stress may be high.
  • the ultrahigh molecular weight polyethylene having a weight average molecular weight of 1.0 ⁇ 10 6 or more is included in the above range, a microporous which has high strength and excellent melt heat shrinkage stress without impairing the productivity of the microporous polyolefin membrane A membrane can be obtained.
  • the polyethylene resin may be a single polyethylene or a mixture of two or more polyethylenes.
  • the said polyolefin resin can contain other resin components other than the said polyethylene resin as needed.
  • the other resin component is preferably a heat resistant resin, and as the heat resistant resin, for example, a crystalline resin having a melting point of 150 ° C. or higher (including a partially crystalline resin), and / or a glass
  • a crystalline resin having a melting point of 150 ° C. or higher including a partially crystalline resin
  • An amorphous resin having a point transfer (TG) of 150 ° C. or higher can be mentioned.
  • TG is a value measured in accordance with JIS K7121.
  • resin components include polyester, polymethylpentene [PMP or TPX (Transparent polymer X), melting point: 230 to 245 ° C.], polyamide (PA, melting point: 215 to 265 ° C.), polyarylene sulfide ( PAS), fluorinated resins such as polyvinylidene fluoride homopolymers such as polyvinylidene fluoride (PVDF), fluorinated olefins such as polytetrafluoroethylene (PTFE), and copolymers thereof; polystyrene (PS, melting point: 230 ° C.
  • PMP or TPX Transparent polymer X
  • PA melting point: 215 to 265 ° C.
  • PAS polyarylene sulfide
  • fluorinated resins such as polyvinylidene fluoride homopolymers such as polyvinylidene fluoride (PVDF), fluorinated olefins such as polytetrafluoroethylene
  • Polyvinyl alcohol PVA, melting point: 220 to 240 ° C.
  • polyimide PI, Tg: 280 ° C. or more
  • polyamideimide PAI, Tg: 280 ° C.
  • PES polyether sulfone
  • PEEK Polyether ether ketone
  • PC Polycarbonate
  • PC melting point: 220-240 ° C
  • cellulose acetate melting point: 220 ° C
  • cellulose triacetate melting point: 300 ° C
  • polysulfone Tg: 190 ° C
  • polyetherimide melting point: 216 ° C
  • the resin component is not limited to one consisting of a single resin component, and may consist of a plurality of resin components.
  • the preferred weight average molecular weight (Mw) of the other resin components varies depending on the type of resin, but is generally 1 ⁇ 10 3 to 1 ⁇ 10 6 , more preferably 1 ⁇ 10 4 to 7 ⁇ 10 5 .
  • the content of the other resin component in the polyolefin resin is appropriately adjusted without departing from the scope of the present invention, but is contained in the range of about 10% by mass or less in the polyolefin resin.
  • polystyrene resin if necessary, other polyolefins other than the above-mentioned polyethylene may be contained, and polybutene-1 polybutene-1 having a Mw of 1.0 ⁇ 10 4 to 4.0 ⁇ 10 6 , polypentene- 1, at least one selected from the group consisting of polyhexene-1, polyoctene-1 and polyethylene wax having an Mw of 1.0 ⁇ 10 3 to 1.0 ⁇ 10 4 .
  • content of polyolefins other than the said polyethylene can be suitably adjusted in the range which does not impair the effect of this invention, 10 mass% or less is preferable in said polyolefin resin, less than 5 mass% is more preferable, and 0 mass% is more preferable. Is more preferred.
  • the microporous film of this embodiment contains a crystal nucleating agent.
  • the crystal nucleating agent that can be used for the microporous membrane of the present embodiment is not particularly limited, and general compound-based and particle-based crystal nucleating agents used for polyolefin resins can be used.
  • a nucleating agent it may be a masterbatch in which the nucleating agent is previously mixed and dispersed in a polyolefin resin.
  • the blending amount of the crystal nucleating agent is not particularly limited, but the upper limit thereof is preferably 10 parts by mass or less, more preferably 5 parts by mass or less with respect to 100 parts by mass of the polyolefin resin, and the lower limit is 100 parts by mass of the polyolefin resin. 0.00001 mass part or more is preferable, and 0.0001 mass part or more is more preferable.
  • the compounding amount of the crystal nucleating agent is in the above range, good dispersibility in the polyolefin resin and good handling workability and economy in the manufacturing process can be expected.
  • Compound based crystal nucleating agent examples include cyclics such as sodium benzoate, aluminum salt of 4-tert-butyl benzoate, sodium adipate and disodium bicyclo [2.2.1] heptane-2,3-dicarboxylate.
  • Hydrocarbon carboxylic acid metal salts such as sodium laurate and zinc stearate, sodium bis (4-tert-butylphenyl) phosphate, sodium-2,2'-methylene bis Acetal skeletons such as dibenzylidenesorbitol, bis (methylbenzylidene) sorbitol and bis (dimethylbenzylidene) sorbitol, such as tributylphenyl) phosphate and lithium-2,2'-methylenebis (4,6-di-tert-butylphenyl) phosphate
  • the compound which has can be used. Furthermore, from the viewpoint of improving the strength, it is preferable to use an aromatic phosphate metal salt or an aliphatic metal salt.
  • group crystal nucleating agent fine particle type
  • a crystal nucleating agent marketed for example, “Gelol D” (made by Shin Nippon Rika Co., Ltd.), “Adeka stub” (made by Adeka company), “HYPERFORM” (made by Milliken Chemical Co., Ltd.) "Pine Crystal” (Arakawa Industrial Chemical Co., Ltd.) Or “IRGACLEAR D” (manufactured by Ciba Specialty Chemicals).
  • "Rike master” made by Riken vitamin company
  • the polyolefin resin as described above may be, if necessary, an antioxidant (eg, tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl)].
  • an antioxidant eg, tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl
  • Various additives such as propionate] methane, UV absorbers, pigments, dyes and the like can be blended within the range not impairing the object of the present invention.
  • the amount is preferably 0.01 parts by mass to 10 parts by mass with respect to 100 parts by mass of the polyolefin resin. If the amount is less than 0.01 parts by mass, sufficient effects may not be obtained, or the control of the addition amount at the time of production may be difficult.
  • the method for producing a polyolefin microporous membrane according to the embodiment of the present invention is not particularly limited as long as a polyolefin microporous membrane having the above-mentioned characteristics can be produced, and a conventionally known method may be used.
  • a conventionally known method may be used.
  • the methods described in Japanese Patent No. 2132327 and Japanese Patent No. 3347835, International Patent Publication No. 2006/137540, etc. can be used.
  • a step of melt-kneading the polyolefin resin, a crystal nucleating agent and a film forming solvent to prepare a polyolefin resin composition (2) A step of extruding the polyolefin resin composition and cooling to form a gel-like sheet (3 1) A first stretching step of stretching the gel-like sheet (4) a step of removing a film-forming solvent from the gel-like sheet after the stretching (5) a step of drying the sheet after removing the film-forming solvent 2.) a second stretching step of stretching the dried sheet (7) a step of heat treating the dried sheet (8) a step of crosslinking and / or hydrophilizing the sheet after the stretching step
  • Step of Preparing Polyolefin Resin Composition After a crystal nucleating agent and a suitable solvent for film formation are blended in a polyolefin resin, it is melt-kneaded to prepare a polyolefin resin composition.
  • a melt-kneading method for example, a method using a twin-screw extruder described in Japanese Patent No. 2132327 and Japanese Patent No. 3347835 can be used.
  • the melt-kneading method is known and thus the description thereof is omitted.
  • the blending ratio of the polyolefin resin and the film forming solvent in the polyolefin resin composition is not particularly limited, but is preferably 50 to 80 parts by mass with respect to 20 to 50 parts by mass of the polyolefin resin. More preferably, the film forming solvent is 60 to 75 parts by mass with respect to 25 to 40 parts by mass of the polyolefin resin.
  • blended with a polyolefin resin composition is as above-mentioned.
  • the polyolefin resin composition is fed from an extruder to a die and extruded into a sheet. Multiple polyolefin resin compositions of the same or different composition may be fed from the extruder to one die where they may be laminated in layers and extruded into sheets.
  • the extrusion method may be either a flat die method or an inflation method.
  • the extrusion temperature is preferably 140 to 250 ° C., and the extrusion speed is preferably 0.2 to 15 m / min.
  • the film thickness can be adjusted by adjusting each extrusion amount of the polyolefin resin composition.
  • the extrusion method for example, the methods disclosed in Japanese Patent No. 2132327 and Japanese Patent No.
  • a gel-like sheet By cooling the obtained extruded body, a gel-like sheet is formed.
  • a method of forming a gel-like sheet for example, the methods disclosed in Japanese Patent No. 2132327 and Japanese Patent No. 3347835 can be used.
  • the cooling is preferably performed at a rate of 50 ° C./min or more at least to the gelation temperature, more preferably 100 ° C./min or more, and still more preferably 150 ° C./min or more. It is preferable to cool the gel sheet to 50 ° C. or less, more preferably 40 ° C. or less, still more preferably 30 ° C. or less, and particularly preferably 20 ° C. or less.
  • the gel sheet in addition to the fact that the crystallization rate is increased by the addition of the crystal nucleating agent etc., the gel sheet is uniformly cooled by performing cooling of the gel sheet under the above range. It becomes possible to raise the property, and it becomes possible to promote further strength improvement in the subsequent drawing step.
  • the obtained gel-like sheet is stretched in at least one uniaxial direction. Since the gel-like sheet contains a film-forming solvent, it can be stretched uniformly. After heating, the gel-like sheet is preferably stretched at a predetermined magnification by a tenter method, a roll method, an inflation method, or a combination thereof. Although stretching may be uniaxial stretching or biaxial stretching, biaxial stretching is preferred. In the case of biaxial stretching, any of simultaneous biaxial stretching, sequential stretching and multi-stage stretching (for example, a combination of simultaneous biaxial stretching and sequential stretching) may be used. In the case of uniaxial stretching, the stretch ratio (area stretch ratio) in this step is preferably 5 times or more, and more preferably 10 to 100 times.
  • the longitudinal and transverse directions are preferably 5 or more, and the draw ratios in the MD and TD directions may be the same or different. If the draw ratio is less than 30 times, the mechanical strength may be lowered, which is not preferable. In addition, when the stretching ratio is 150 times or more, the possibility of the film breakage is increased, which is not preferable.
  • the draw ratio in this process means the area draw ratio of the microporous film just before being provided to the following process on the basis of the microporous film just before this process.
  • the stretching temperature in this step is preferably in the range of crystal dispersion temperature (TCD) to TCD + 30 ° C. of the polyolefin resin, and is in the range of crystal dispersion temperature (TCD) + 5 ° C. to crystal dispersion temperature (TCD) + 28 ° C. Of TCD + 10 ° C. to TCD + 26 ° C. is particularly preferable.
  • TCD crystal dispersion temperature
  • the crystal dispersion temperature (TCD) is determined by temperature characteristic measurement of dynamic viscoelasticity according to ASTM D4065.
  • Ultrahigh molecular weight polyethylene, polyethylene other than ultra high molecular weight polyethylene and polyethylene compositions have a crystal dispersion temperature of about 90 to 100 ° C., so the stretching temperature is preferably 90 to 130 ° C., more preferably 110 to 120 ° C. More preferably to 114-117.degree.
  • the stretching as described above causes cleavage between polyethylene lamellas to refine the polyethylene phase and form a large number of fibrils.
  • the fibrils form a three-dimensionally irregularly linked network structure.
  • the film-forming solvent is removed (washed) using a washing solvent. Since the polyolefin phase is separated from the film forming solvent phase, when the film forming solvent is removed, it is composed of fibrils forming a fine three-dimensional network structure, and three-dimensionally irregularly communicated holes (voids) A porous membrane is obtained.
  • the cleaning solvent and the method for removing the film forming solvent using the same are known and thus the description thereof is omitted. For example, the methods disclosed in Japanese Patent No. 2132327 and Japanese Patent Laid-Open No. 2002-256099 can be used.
  • the microporous film from which the film-forming solvent has been removed is dried by a heat-drying method or an air-drying method.
  • the drying temperature is preferably equal to or less than the crystal dispersion temperature (TCD) of the polyolefin resin, and particularly preferably 5 ° C. or more lower than TCD.
  • TCD crystal dispersion temperature
  • the drying is preferably performed until the remaining amount of the washing solvent is 5 parts by mass or less, and more preferably 3 parts by mass or less, with 100 parts by mass (dry weight) of the microporous membrane.
  • Second Stretching Step It is preferable to stretch the microporous membrane after drying in at least one uniaxial direction.
  • the stretching of the microporous membrane can be carried out by a tenter method, a roll method or the like while heating as described above. Stretching may be uniaxial stretching or biaxial stretching. In the case of biaxial stretching, either simultaneous biaxial stretching or sequential stretching may be used.
  • the stretching temperature in this step is not particularly limited, but is usually 90 to 135 ° C., more preferably 95 to 130 ° C.
  • the lower limit of the stretching ratio (area stretching ratio) in the uniaxial direction of stretching of the microporous membrane in this step is preferably 1.0 or more, more preferably 1.1 or more, and still more preferably 1.2. More than double.
  • an upper limit shall be 5.0 times or less.
  • the stretching ratio is 1.0 to 5.0 times in the MD direction or TD direction.
  • the lower limit of the area stretching ratio is preferably 1.0 or more, more preferably 1.1 or more, and still more preferably 1.2 or more.
  • the upper limit is preferably 16.0 times or less, and the MD direction and the TD direction may be 1.0 to 4.0 times, respectively, and the draw ratio in the MD direction and the TD direction may be the same or different.
  • the draw ratio in this process means the draw ratio of the microporous membrane just before being provided to the following process on the basis of the microporous film just before this process.
  • the microporous membrane after drying can be heat treated.
  • the heat treatment stabilizes the crystals and makes the lamella uniform.
  • a heat treatment method a heat setting treatment and / or a heat relaxation treatment can be used.
  • the heat setting treatment is a heat treatment which is heated while keeping the dimensions of the film unchanged.
  • the thermal relaxation treatment is a heat treatment which causes the film to be thermally shrunk in the MD direction or the TD direction during heating.
  • the heat setting treatment is preferably performed by a tenter method or a roll method.
  • the heat relaxation treatment method as described in Japanese Patent Application Laid-Open No.
  • the heat treatment temperature is preferably in the range of TCD to TM of the polyolefin resin, more preferably in the range of stretching temperature ⁇ 5 ° C. of the microporous membrane, and particularly preferably in the range of second stretching temperature ⁇ 3 ° C. of the microporous membrane.
  • the microporous film after bonding or stretching may be further subjected to crosslinking treatment and hydrophilization treatment.
  • the crosslinking treatment is performed on the microporous film by irradiation of ionizing radiation such as ridges, ridges, ridges, and electron beams.
  • ionizing radiation such as ridges, ridges, ridges, and electron beams.
  • electron beam irradiation an electron dose of 0.1 to 100 MRAD is preferable, and an accelerating voltage of 100 to 300 KV is preferable.
  • the crosslinking treatment raises the meltdown temperature of the microporous membrane.
  • the hydrophilization treatment can be performed by monomer grafting, surfactant treatment, corona discharge, or the like. Monomer grafting is preferably carried out after the crosslinking treatment.
  • Laminated microporous membrane A porous layer may be provided on at least one surface of the polyolefin microporous film to form a laminated porous film.
  • the porous layer formed using the filler containing resin solution containing a filler and a resin binder, or a heat resistant resin solution can be mentioned, for example.
  • the polyolefin microporous film according to the embodiment of the present invention can be suitably used in any of a battery using an aqueous electrolyte and a battery using a non-aqueous electrolyte.
  • it can be preferably used as a separator of secondary batteries such as nickel-hydrogen batteries, nickel-cadmium batteries, nickel-zinc batteries, silver-zinc batteries, lithium secondary batteries, lithium polymer secondary batteries and the like.
  • secondary batteries such as nickel-hydrogen batteries, nickel-cadmium batteries, nickel-zinc batteries, silver-zinc batteries, lithium secondary batteries, lithium polymer secondary batteries and the like.
  • a positive electrode and a negative electrode are stacked via a separator, and the separator contains an electrolytic solution (electrolyte).
  • the structure of the electrode is not particularly limited, and a conventionally known structure can be used.
  • an electrode structure coin type in which a disk-shaped positive electrode and a negative electrode are disposed to face each other, a flat plate-shaped positive electrode and a negative electrode
  • An alternately stacked electrode structure stacked type
  • an electrode structure wound type in which stacked strip-like positive and negative electrodes are wound, or the like
  • the current collector, the positive electrode, the positive electrode active material, the negative electrode, the negative electrode active material, and the electrolytic solution used for the lithium ion secondary battery are not particularly limited, and conventionally known materials can be appropriately combined and used.
  • the present invention is not limited to the above-described embodiment, and can be variously modified and implemented within the scope of the invention.
  • Film thickness The film thickness of five points in the range of 95 mm ⁇ 95 mm of the microporous film was measured by a contact thickness meter (Lightmatic, manufactured by Mitutoyo Co., Ltd.), and the average value of the film thickness T was determined.
  • Porosity [(volume-weight / polymer density) / volume] x 100
  • Air resistance sec./100 cc
  • the pore size was converted from the pressure at the point where the curve showing the slope of 1/2 of the flow curve by the DRY-UP measurement and the curve of the WET-UP measurement intersect.
  • the following equation was used for conversion of pressure and pore size.
  • D C ⁇ ⁇ / P (In the above formula, “D ( ⁇ m)” is the pore diameter of the microporous membrane, “ ⁇ (mN / m)” is the surface tension of the liquid, “P (Pa)” is the pressure, and “C” is a constant.
  • Weight average molecular weight (Mw) and polyethylene content ratio of Mw 1.0 ⁇ 10 6 or more in polyolefin microporous film (% by mass)
  • the weight average molecular weight of the microporous membrane made of UHMwPE, HDPE and polyolefin was determined by gel permeation chromatography (GPC) under the following conditions.
  • Measurement device GPC-150C made by WATERS CORPORATION ⁇ Column: Showa Denko KK SHODEX UT806M ⁇ Column temperature: 135 ° C Solvent (mobile phase): O-dichlorobenzene Solvent flow rate: 1.0 mL / min Sample concentration: 0.1 wt% (dissolution condition: 135 ° C./1 H) Injection amount: 500 ⁇ L -Detector: WATERS CORPORATION differential refractometer (RI detector) Calibration curve: A calibration curve obtained using a monodispersed polystyrene standard sample was prepared using a predetermined conversion constant.
  • the content ratio of polyethylene having a Mw of 1.0 ⁇ 10 6 or more in the microporous membrane made of polyolefin was determined from the measurement results of the weight average molecular weight of the microporous membrane made of polyolefin in the above method.
  • 126 ° C. half crystallization time T 1/2 (seconds) Measurement was carried out at three different points in the same microporous membrane by the following method, and the average value was set to a half crystallization time T 1/2 of 126 ° C.
  • the 126 ° C. half crystallization time T 1/2 was measured by the following method. A microporous polyolefin membrane was sealed in a measurement pan, heated to 230 ° C. and completely melted using PYRIS DIAMOND DSC manufactured by PARKING ELMER, and then held at 230 ° C. for 10 minutes. Then, the temperature was lowered to 126 ° C. at 30 ° C./min and held at 126 ° C. The time change of the heat quantity after entering the isothermal control at 126 ° C. was recorded, and the time when the peak area became half was regarded as 126 ° C. half crystallization time T 1/2 .
  • Crystal melting peak area ratio (%) The measurement was performed at three different points in the same microporous film according to the following method, and the area ratio of the crystal melting peak was 141 ° C. or more.
  • a microporous polyolefin membrane was sealed in a measurement pan, and the temperature was raised to 230 ° C. using PYRIS DIAMOND DSC manufactured by PARKING ELMER to measure the crystal melting peak.
  • the ratio of the heat of melting of the whole of the obtained crystal melting peak to the heat of melting of 141 ° C. or higher was taken as the area ratio of crystal melting peak of 141 ° C. or more (the ratio of melting peak area of 141 ° C. or more).
  • MD and TD solid thermal contraction rate (%)
  • the solid heat shrinkage ratio of the microporous film was obtained by heating the microporous film cut out to 95 mm ⁇ 95 mm at 105 ° C. for 8 hours and changing the MD and TD dimensions of the microporous film before and after heating. The above measurement was performed at three different points in the same microporous film, and the average value of the MD and TD solid thermal contraction rates was determined.
  • the above measurement is carried out at three different points in the same microporous film for MD and TD, and the average value is taken as the MD melting heat shrinkage stress and the TD melting heat shrinkage stress, respectively, and their sum is MD + TD It was set as the melting heat shrinkage stress.
  • Breakdown voltage test In order to evaluate the withstand voltage between the electrodes, a breakdown voltage test was carried out as follows. The micro-porous membrane cut out in a circle of 60 mm in diameter is placed on a square aluminum plate of 150 mm on a side, and a cylindrical electrode of 50 mm in diameter, 30 mm in height and 500 g in weight made of brass is placed on it. A TOS5051A dielectric breakdown resistance tester was connected. A voltage was applied at a pressure rising speed of 0.2 kV / sec, and a voltage (V1) at the time when the microporous film with film thickness T1 ( ⁇ m) and porosity P1 (%) broke down was read.
  • the dielectric breakdown voltage was measured 15 times each to obtain an average value. In the case where the average value is 0.15 kV / ⁇ m or more, the possibility of local short circuiting is low, and the case of ⁇ is less than 0.15 kV / ⁇ m.
  • This slurry was applied by a die coater on one side of a 20 ⁇ m thick aluminum foil serving as a positive electrode current collector at an active material application amount of 250 g / m 2 and an active material bulk density of 3.00 g / cm 3 . Then, it was dried at 130 ° C. for 3 minutes, compression-molded by a roll press, and cut into a strip having a width of about 57 mm.
  • a slurry was prepared by dispersing 96.9% by mass of artificial graphite as an active material, 1.4% by mass of ammonium salt of carboxymethylcellulose as a binder and 1.7% by mass of styrene-butadiene copolymer latex in purified water.
  • This slurry was coated with a die coater on one side of a 12 ⁇ m-thick copper foil to be a negative electrode current collector with a high filling density of 106 g / m 2 of active material application amount and 1.55 g / cm 3 of active material bulk density. Attached. Then, it was dried at 120 ° C. for 3 minutes, compression-molded by a roll press, and cut into a strip having a width of about 58 mm.
  • a strip-shaped negative electrode, a separator, a strip-shaped positive electrode, and a separator were stacked in this order and spirally wound with a winding tension of 100 gf to prepare an electrode plate laminate.
  • This electrode plate laminate is housed in a stainless steel container having an outer diameter of 18 mm and a height of 65 mm, and an aluminum tab derived from a positive electrode current collector is made to nickel on a container lid terminal portion and nickel derived from a negative electrode current collector. The tabs were welded to the vessel wall. After drying for 12 hours at 80 ° C. under vacuum, the non-aqueous electrolyte was injected into the vessel in an argon box and sealed.
  • ⁇ Pre-processing> Charge the assembled battery at a current value of 1/3 C to a voltage of 4.2 V, perform constant voltage charging of 4.2 V for 5 hours, and then discharge it to a final voltage of 3.0 V with a current of 1/3 C. The Next, after constant current charging to a voltage of 4.2 V with a current value of 1 C, constant voltage charging of 4.2 V was performed for 2 hours, and then discharging was performed to a final voltage of 3.0 V with a current of 1 C. Finally, after constant current charging to a current value of 1 C up to 4.2 V, constant voltage charging at 4.2 V was performed for 2 hours for pretreatment.
  • Example 1 Polyethylene (PE) consisting of 10 parts by mass of ultrahigh molecular weight polyethylene (UHMwPE) having a weight average molecular weight (Mw) of 2.0 ⁇ 10 6 and 90 parts by mass of high density polyethylene (HDPE) having a Mw of 2.8 ⁇ 10 5 ) 0.375 parts by mass of tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate] methane in 100 parts by mass of the composition, and masterbatch Rikemaster CN-002 ( RIKEN vitamin product: 1 part by mass of a nucleating agent content of about 2% by mass was dry-blended to obtain a mixture.
  • UHMwPE ultrahigh molecular weight polyethylene
  • HDPE high density polyethylene
  • the extruded molded body was cooled while being pulled up by a cooling roll adjusted to 20 ° C. to form a gel-like sheet.
  • the obtained gel-like sheet was subjected to simultaneous biaxial stretching so as to be 9 times in MD and 9 times in TD at a stretching temperature of 115 ° C.
  • the stretched membrane was washed in a methylene chloride washing bath heated to 25 ° C. to remove liquid paraffin.
  • the washed membrane was dried in a drying furnace adjusted to 60 ° C., and heat fixed at 125 ° C. for 40 seconds in a tenter to obtain a polyolefin microporous membrane with a thickness of 7 ⁇ m.
  • Table 1 The properties of the obtained microporous membrane are shown in Table 1.
  • Example 2 A polyolefin microporous film with a thickness of 12 ⁇ m was formed in the same manner as in Example 1, except that the biaxial sheet was subjected to simultaneous biaxial stretching so that the gel-like sheet of the polyethylene resin composition is 7 times MD and 7 times TD. Obtained.
  • the properties of the obtained microporous membrane are shown in Table 1.
  • Example 3 To 100 parts by mass of a polyethylene (PE) composition consisting of 100 parts by mass of high density polyethylene (HDPE) having a weight average molecular weight (Mw) of 2.8 ⁇ 10 5 , tetrakis [methylene-3- (3,5-di-) Dry-blend 0.375 parts by mass of tert-butyl 4-hydroxyphenyl) -propionate] methane and 1 part by mass of masterbatch Rikemaster CN-002 (manufactured by Riken Vitamin: nucleating agent content: about 2% by mass), A mixture was obtained.
  • PE polyethylene
  • HDPE high density polyethylene
  • Mw weight average molecular weight
  • a polyolefin microporous film with a thickness of 7 ⁇ m was obtained in the same manner as in Example 1, except that the polyethylene resin composition was prepared by melt-kneading at a temperature of ° C.
  • the properties of the obtained microporous membrane are shown in Table 1.
  • Example 4 7 ⁇ m in thickness in the same manner as in Example 1 except that 100 parts by mass of a polyethylene (PE) composition consisting of 100 parts by mass of high density polyethylene (HDPE) having a weight average molecular weight (Mw) of 2.8 ⁇ 10 5 was used.
  • PE polyethylene
  • HDPE high density polyethylene
  • Mw weight average molecular weight
  • Example 5 A polyolefin microporous film with a thickness of 12 ⁇ m was obtained in the same manner as in Example 3 except that simultaneous biaxial stretching was performed so that the gel-like sheet of the polyethylene resin composition was 7 times in MD and 7 times in TD.
  • the properties of the obtained microporous membrane are shown in Table 1.
  • Example 6 Simultaneous biaxial stretching is performed so that the gel-like sheet of the polyethylene resin composition is 7 times in MD and 7 times in TD, and after removing liquid paraffin, the washed film is dried in a drying furnace adjusted to 60 ° C. After stretching in the MD at 1.22 times at 130 ° C. in a tenter, stretching 1.21 in the TD direction, reducing by 0.9 times in the TD direction, and heat-setting for 40 seconds, In the same manner as in Example 1, a polyolefin microporous film with a thickness of 11 ⁇ m was obtained. The properties of the obtained microporous membrane are shown in Table 1.
  • Comparative Example 1 Master batch Example without using Liquemaster CN-002 (made by Riken Vitamin Co., Ltd.) and carrying out simultaneous biaxial stretching so that the gel-like sheet of polyethylene resin composition is 5 times in MD and 5 times in TD. In the same manner as in 4, a polyolefin microporous film with a thickness of 20 ⁇ m was obtained. The properties of the obtained microporous membrane are shown in Table 2.
  • Comparative Example 2 A polyolefin microporous film with a thickness of 7 ⁇ m was obtained in the same manner as in Comparative Example 1 except that simultaneous biaxial stretching was performed so that the gel-like sheet of the polyethylene resin composition was 7 times in MD and 7 times in TD. The properties of the obtained microporous membrane are shown in Table 2.
  • Comparative Example 3 Master batch Example 1 except that simultaneous biaxial stretching was carried out so that the gel-like sheet of the polyethylene resin composition was 5 times in MD and 5 times in TD without being blended with RIKEMASTER CN-002 (manufactured by Riken Vitamin Co., Ltd.). In the same manner as in the above, a polyolefin microporous film with a thickness of 20 ⁇ m was obtained. The properties of the obtained microporous membrane are shown in Table 2.
  • Comparative Example 4 A polyolefin microporous film with a thickness of 20 ⁇ m was obtained in the same manner as in Example 1 except that the simultaneous biaxial stretching was performed so that the gel-like sheet of the polyethylene resin composition was 5 times in MD and 5 times in TD. The properties of the obtained microporous membrane are shown in Table 3.
  • Comparative Example 5 Polyethylene (PE) consisting of 30 parts by weight of ultra high molecular weight polyethylene (UHMwPE) having a weight average molecular weight (Mw) of 2.0 ⁇ 10 6 and 70 parts by weight of high density polyethylene (HDPE) having a Mw of 2.8 ⁇ 10 5
  • UHMwPE ultra high molecular weight polyethylene
  • HDPE high density polyethylene
  • a polyolefin microporous film with a thickness of 20 ⁇ m was obtained in the same manner as in Comparative Example 3 except that 100 parts by mass of the composition was used.
  • the properties of the obtained microporous membrane are shown in Table 3.
  • Comparative Example 6 A polyolefin microporous film with a thickness of 12 ⁇ m was obtained in the same manner as in Comparative Example 5 except that simultaneous biaxial stretching was performed so that the gel-like sheet of the polyethylene resin composition was 9 times in MD and 9 times in TD. The properties of the obtained microporous membrane are shown in Table 3.
  • Comparative Example 7 Polyethylene (PE) consisting of 30 parts by weight of ultra high molecular weight polyethylene (UHMwPE) with a weight average molecular weight (Mw) of 4.15 ⁇ 10 6 and 70 parts by weight of high density polyethylene (HDPE) with a Mw of 5.6 ⁇ 10 5 A mixture was obtained by dry-blending 100 parts by weight of the composition with 0.375 parts by weight of tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) -propionate] methane.
  • UHMwPE ultra high molecular weight polyethylene
  • HDPE high density polyethylene
  • a polyethylene solution was made.
  • the polyethylene solution was extruded from the die at 148 ° C. and cooled in a water bath to make a gel-like sheet. At this time, the gel-like sheet was extruded from the die and then cooled so that the cooling rate was 90 ° C./min.
  • the gel sheet was stretched by biaxial stretching in which longitudinal stretching and lateral stretching were sequentially performed.
  • the longitudinal stretching was performed at a stretching ratio of 6 times
  • the stretching temperature was 90 ° C.
  • the transverse stretching was performed at a stretching ratio of 9 times
  • the stretching temperature was 105 ° C.
  • Heat setting was performed at 135 ° C. after transverse stretching.
  • it was immersed in a methylene chloride bath to extract liquid paraffin and decalin. Thereafter, it was dried at 50 ° C. and annealed at 120 ° C. to obtain a microporous polyolefin membrane.
  • Table 3 The properties of the obtained microporous membrane are shown in Table 3.
  • Comparative Example 8 Masterbatch A polyolefin microporous film with a thickness of 11 ⁇ m was obtained in the same manner as in Example 6, except that RIKEMASTER CN-002 (manufactured by Riken Vitamin Co., Ltd.) was not blended. The properties of the obtained microporous membrane are shown in Table 4.
  • Comparative Example 9 A polyolefin microporous film having a thickness of 20 ⁇ m was obtained in the same manner as in Example 4 except that the simultaneous biaxial stretching was performed so that the gel-like sheet of the polyethylene resin composition was 5 times in MD and 5 times in TD. The properties of the obtained microporous membrane are shown in Table 4.
  • Comparative Example 10 Master batch Comparative Example 5 except that RIKEMASTER CN-002 (manufactured by Riken Vitamin Co., Ltd.) was blended, and the biaxial sheet was subjected to simultaneous biaxial stretching so that the gel-like sheet of the polyethylene resin composition is 7 times MD and 7 times TD. In the same manner as in the above, a polyolefin microporous film with a thickness of 12 ⁇ m was obtained. The properties of the obtained microporous membrane are shown in Table 4.
  • a polyolefin microporous film according to an embodiment of the present invention has excellent mechanical strength and shape retention characteristics at high temperatures, and in particular, non-aqueous electrolyte secondary batteries represented by lithium ion secondary batteries. It can be suitably used for such secondary batteries.

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Abstract

L'invention concerne une membrane microporeuse qui est constituée de polyoléfine et qui présente une excellente résistance mécanique, telle qu'une résistance à la perforation, et des caractéristiques de rétention de forme à haute température et une uniformité et une sécurité élevées. La membrane microporeuse constituée de polyoléfine est caractérisée en ce que : le temps de demi-cristallisation T1/2 à 126°C est inférieur ou égal à 200 secondes ; la résistance à la perforation pour une porosité de 50 % et une épaisseur de film de 20 µm est supérieure ou égale à 6,0 N/20 µm ; et lorsque les contraintes de retrait thermique, dues à la chaleur de fusion, dans le sens machine MD et le sens transversal TD sont définies comme étant PMD et PTD, respectivement, au moins l'une de PMD et de PTD est inférieure ou égale à 0,8 MPa et PMD+TD, qui est la somme de PMD et PTD, est inférieure ou égale à 1,5 MPa.
PCT/JP2018/032273 2017-09-27 2018-08-30 Membrane microporeuse constituée de polyoléfine, séparateur de batterie et batterie secondaire Ceased WO2019065073A1 (fr)

Priority Applications (3)

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JP2018552017A JP7283080B2 (ja) 2017-09-27 2018-08-30 ポリオレフィン製微多孔膜、電池用セパレータおよび二次電池
KR1020207005414A KR102622533B1 (ko) 2017-09-27 2018-08-30 폴리올레핀제 미다공막, 전지용 세퍼레이터 및 이차 전지
CN201880052513.3A CN111032758A (zh) 2017-09-27 2018-08-30 聚烯烃制微多孔膜、电池用隔膜和二次电池

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JP2017186142 2017-09-27
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JP2023548238A (ja) * 2020-12-15 2023-11-15 上海恩捷新材料科技有限公司 ポリオレフィン微多孔質フィルム及びその生産システム、電池セパレータ、電気化学装置
WO2024019069A1 (fr) * 2022-07-20 2024-01-25 東レ株式会社 Membrane microporeuse en polyoléfine, séparateur pour batteries et batterie
US11976177B2 (en) 2020-07-01 2024-05-07 Celanese International Corporation Polymer composition and membranes made therefrom with improved mechanical strength
US12247110B2 (en) 2019-06-21 2025-03-11 Asahi Kasei Battery Separator Corporation Polyolefin microporous membrane
KR102952801B1 (ko) 2019-03-29 2026-04-16 도레이 카부시키가이샤 폴리올레핀 미다공막, 전지용 세퍼레이터, 이차전지 및 폴리올레핀 미다공막의 제조 방법

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KR20230141102A (ko) 2022-03-31 2023-10-10 도레이배터리세퍼레이터필름 한국유한회사 폴리올레핀 미다공질막 및 이를 사용한 전지용 세퍼레이터
CN115149205A (zh) * 2022-06-23 2022-10-04 中材锂膜(宁乡)有限公司 一种基于吹膜工艺的湿法锂电池隔膜的制备方法及系统

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KR102952801B1 (ko) 2019-03-29 2026-04-16 도레이 카부시키가이샤 폴리올레핀 미다공막, 전지용 세퍼레이터, 이차전지 및 폴리올레핀 미다공막의 제조 방법
US12247110B2 (en) 2019-06-21 2025-03-11 Asahi Kasei Battery Separator Corporation Polyolefin microporous membrane
JP2021116316A (ja) * 2020-01-22 2021-08-10 旭化成株式会社 ポリオレフィン微多孔膜
US11976177B2 (en) 2020-07-01 2024-05-07 Celanese International Corporation Polymer composition and membranes made therefrom with improved mechanical strength
JP2023548238A (ja) * 2020-12-15 2023-11-15 上海恩捷新材料科技有限公司 ポリオレフィン微多孔質フィルム及びその生産システム、電池セパレータ、電気化学装置
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WO2024019069A1 (fr) * 2022-07-20 2024-01-25 東レ株式会社 Membrane microporeuse en polyoléfine, séparateur pour batteries et batterie

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TW201920406A (zh) 2019-06-01
KR20200060353A (ko) 2020-05-29

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