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WO2011114664A1 - Membranes microporeuses, leurs procédés de fabrication, et utilisation desdites membranes en tant que films de séparation d'éléments de batterie - Google Patents

Membranes microporeuses, leurs procédés de fabrication, et utilisation desdites membranes en tant que films de séparation d'éléments de batterie Download PDF

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Publication number
WO2011114664A1
WO2011114664A1 PCT/JP2011/001398 JP2011001398W WO2011114664A1 WO 2011114664 A1 WO2011114664 A1 WO 2011114664A1 JP 2011001398 W JP2011001398 W JP 2011001398W WO 2011114664 A1 WO2011114664 A1 WO 2011114664A1
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WIPO (PCT)
Prior art keywords
membrane
range
polymer
polyethylene
less
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Ceased
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PCT/JP2011/001398
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English (en)
Inventor
Shintaro Kikuchi
Yoichi Matsuda
Kazuhiro Yamada
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Toray Battery Separator Film Co Ltd
Original Assignee
Toray Tonen Speciality Separator GK
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Priority to CN201180012661.0A priority Critical patent/CN102884116B/zh
Priority to JP2012533809A priority patent/JP2013522379A/ja
Priority to KR1020127023425A priority patent/KR101841513B1/ko
Publication of WO2011114664A1 publication Critical patent/WO2011114664A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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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
    • 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
    • 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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/04—Homopolymers or copolymers of ethene
    • C08L23/06—Polyethene
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
    • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
    • C08L23/10—Homopolymers or copolymers of propene
    • 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
    • H01M50/489—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
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2105/00—Condition, form or state of moulded material or of the material to be shaped
    • B29K2105/04—Condition, form or state of moulded material or of the material to be shaped cellular or porous
    • B29K2105/041—Microporous
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2203/00—Applications
    • C08L2203/16—Applications used for films
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/02—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group
    • C08L2205/025—Polymer mixtures characterised by other features containing two or more polymers of the same C08L -group containing two or more polymers of the same hierarchy C08L, and differing only in parameters such as density, comonomer content, molecular weight, structure
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
    • C08L2205/00—Polymer mixtures characterised by other features
    • C08L2205/03—Polymer mixtures characterised by other features containing three or more polymers in a blend
    • 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 microporous membranes having high meltdown temperature and useful affinity to polymer electrolyte of lithium ion polymer batteries.
  • the invention also relates to the production of these membranes and the use of these membranes as battery separator film.
  • Microporous membranes are useful as battery separator film ("BSF”) for primary and secondary batteries.
  • batteries include lithium ion secondary batteries, lithium ion polymer secondary batteries, nickel-hydrogen batteries, nickel-cadmium batteries, nickel-zinc batteries, silver-zinc batteries, etc.
  • Microporous polymeric membranes can be used as battery separator film ("BSF") in, e.g., lithium ion batteries.
  • BSF battery separator film
  • Such membranes have increased polymer mobility at elevated battery temperature, which leads to a significant permeability decrease.
  • This effect is beneficial in BSFs because the permeability decrease at elevated temperature results in a decrease in battery electrochemical activity, thereby lessening the risk of battery failure under overcharge, rapid-discharge, or other high-temperature battery conditions. Since battery internal temperature can continue to increase even at reduced electrochemical activity (e.g., from temperature overshoot), it is desirable to increase membrane thermal stability at elevated temperature to further lessen the risk of battery failure.
  • a high melting-point species e.g., polypropylene
  • the temperature difference between polyethylene and polypropylene melting points and their physical incompatibility leads to difficulties in producing membranes containing both polymers, particularly when the membrane is thin.
  • Lithium ion batteries in which the electrolyte is a gel electrolyte or polymeric electrolyte, e.g., the electrolyte is contained within a polymeric medium (“lithium ion polymer batteries”) generally utilize BSFs comprising a polymer compatible with (e.g., has affinity for) the polymeric medium in which the electrolyte is contained.
  • BSFs for lithium ion polymer batteries generally have a significantly smaller thickness compared to BSFs commonly used in, e.g., cylindrical and prismatic-format lithium ion batteries.
  • the invention relates to a membrane comprising at least 1 wt.% polyethylene and 4.0 wt.% to 20.0 wt.% polypropylene having an Mw of 5.0 x 10 5 or more and a delta Hm of 80.0 J/g or more, the weight percent being based on the weight of polymer in the membrane; wherein the membrane is microporous and has a thickness of 12.0 micrometer or less.
  • the invention in another embodiment, relates to a process for producing a microporous membrane, comprising: (1) extruding a mixture of diluent and polymer, the polymer comprising an amount A 1 of polyethylene, and an amount A 2 of polypropylene, wherein A 1 is 1.0 wt.% or more, e.g., in the range of from 80.0 wt.% to 96.0 wt.%, and A 2 is in the range of from 4.0 wt.% to 20.0 wt.% with the weight percents being based on the weight of polymer in the polymer-diluent mixture; (2) stretching the extrudate in at least one planar direction; and (3) removing at least a portion of the diluent from the stretched extrudate.
  • the membranes of the present invention have both an improved meltdown temperature and sufficient electrolyte affinity.
  • microporous membranes comprising polyethylene and having a thickness of 12.0 micrometer or less typically have meltdown temperatures less than 145.0 degrees Celsius. It has also been observed that when the polyethylene is combined with polypropylene, these membranes have increased meltdown temperature but decreased affinity for polymer electrolyte.
  • the invention is based, at least in part, on the discovery that these difficulties can be overcome when the membrane comprises a mixture of 1.0 wt.% or more polyethylene and 4.0 wt.% to 20.0 wt.% (based on the weight of the membrane) of polypropylene having a weight average molecular weight ("Mw") of 5.0 x 10 5 or more and a heat of fusion ("delta Hm”) of 80.0 J/g or more, the weight percents being based on the weight of the membrane.
  • Mw weight average molecular weight
  • delta Hm heat of fusion
  • polymer means a composition including a plurality of macromolecules, the macromolecules containing recurring units derived from one or more monomers.
  • the macromolecules can have different size, molecular architecture, atomic content, etc.
  • polymer includes macromolecules such as copolymer, terpolymer, etc.
  • Polyethylene means polyolefin containing 50% or more (by number) recurring ethylene-derived units, preferably polyethylene homopolymer and/or polyethylene copolymer wherein at least 85% (by number) of the recurring units are ethylene units.
  • Polypropylene means polyolefin containing more than 50.0% (by number) recurring propylene-derived units, preferably polypropylene homopolymer and/or polypropylene copolymer wherein at least 85% (by number) of the recurring units are propylene units.
  • isotactic polypropylene means polypropylene having a meso pentad fraction about 50.0 mol.% or more of mmmm pentads, preferably 96.0 mol.% or more of mmmm pentads (based on the total number of moles of isotactic polypropylene).
  • a "microporous membrane” is a thin film having pores, where 90.0 percent or more (by volume) of the film's pore volume resides in pores having average diameters in the range of from 0.01 micrometer to 10.0 micrometer.
  • MD machine direction
  • TD transverse direction
  • MD and TD can be referred to as planar directions of the membrane, where the term "planar” in this context means a direction lying substantially in the plane of the membrane when the membrane is flat.
  • the invention relates to a membrane comprising polyethylene and polypropylene, the membrane being microporous and having a thickness of 12.0 micrometer or less.
  • the microporous membrane comprises an amount of polyethylene (A 1 ) and an amount polypropylene (A 2 ), the polypropylene having an Mw of 5.0 x 10 5 or more and a delta Hm of 80.0 J/g or more.
  • a 1 and A 2 can be expressed as weight percents, based on the weight of polymer in the membrane.
  • the weight percents are based on the weight of the membrane, e.g., as can be the case when the membrane consists essentially of (or even consists of) the polyethylene and polypropylene only.
  • a 1 is in the range of from 80.0 wt.% to 96.0 wt.%
  • a 2 is in the range of from 4.0 wt.% to 20.0 wt.%, the A 1 and A 2 weight percents being based on a combined weight of A1 and A2 equal to 100 wt.%.
  • a 1 is in the range of from 84.5 wt.% to 95.5 wt.%, e.g., in the range of from 94.75 wt.% to 95.25 wt.%.
  • a 2 is in the range of from 4.5 wt.% to 15.5 wt.%, e.g., in the range of from 4.75 wt.% to 5.25 wt.%.
  • the polyethylene can comprise a mixture or reactor blend of polyethylene, such as a mixture of two or more polyethylenes ("PE1", “PE2”, “PE3”, etc., as described below).
  • the PE may include a blend of (i) a first PE (PE1) and/or a second PE (PE2) and (ii) a third PE (PE3).
  • PE1 a first PE
  • PE2 a second PE
  • PE3 a third PE
  • the first PE can be, e.g., a PE having an Mw less than 1.0 x 10 6 , e.g., in the range of from about 1.0 x 10 5 to about 0.90 x 10 6 ; an MWD of 50.0 or less, e.g., in the range of from about 2.0 to about 20.0; and a terminal unsaturation amount less than 0.20 per 1.0 x 10 4 carbon atoms.
  • PE1 has an Mw in the range of from about 4.0 x 10 5 to about 6.0 x 10 5 , and a molecular weight distribution ("MWD", defined as Mw divided by the number average molecular weight) of from about 3.0 to about 10.0.
  • MWD molecular weight distribution
  • PE1 has an amount of terminal unsaturation of 0.14 or less per 1.0 x 10 4 carbon atoms, or, 0.12 or less per 1.0 x 10 4 carbon atoms, e.g., in the range of from 0.05 to 0.14 per 1.0 x 10 4 carbon atoms (e.g., below the detection limit of the measurement).
  • PE2 has an amount of terminal unsaturation of 0.14 or less per 1.0 x 10 4 carbon atoms, or, 0.12 or less per 1.0 x 10 4 carbon atoms, e.g., in the range of from 0.05 to 0.14 per 1.0 x 10 4 carbon atoms (e.g., below the detection limit of the measurement).
  • the second PE can be, e.g., PE having an Mw less than 1.0 x 10 6 , e.g., in the range of from about 2.0 x 10 5 to about 0.9 x 10 6 , an MWD of 50.0 or less, e.g., in the range of from about 2 to about 50, and a terminal unsaturation amount 0.20 more than per 1.0 x 10 4 carbon atoms.
  • PE2 has an amount of terminal unsaturation 0.30 more than per 1.0 x 10 4 carbon atoms, or 0.50 more than per 1.0 x 10 4 carbon atoms, e.g., in the range of 0.6 to 10.0 per 1.0 x 10 4 carbon atoms.
  • a non-limiting example of PE2 is one having an Mw in the range of from about 3.0 x 10 5 to about 8.0 x 10 5 , for example about 7.5 x 10 5 , and an MWD of from about 4 to about 15.
  • PE1 and/or PE2 can be, e.g., an ethylene homopolymer or an ethylene/alpha-olefin copolymer containing 5.0 mol.% or less of one or more comonomer such as alpha-olefin, based on 100% by mole of the copolymer.
  • the alpha-olefin is one or more of propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene-1, vinyl acetate, methyl methacrylate, or styrene.
  • Such a PE can have a melting point of 132 degrees Celsius or more.
  • PE1 can be produced, e.g., in a process using a Ziegler-Natta or single-site polymerization catalyst, but this is not required.
  • the amount of terminal unsaturation can be measured in accordance with the procedures described in PCT Publication WO 97/23554, for example.
  • PE2 can be produced using a chromium-containing catalyst, for example.
  • PE3
  • the third PE can be, e.g., PE having an Mw of 1.0 x 10 6 or more, e.g., in the range of from about 1.0 x 10 6 to about 5.0 x 10 6 and an MWD of from about 1.2 to about 50.0.
  • PE3 is one having an Mw of from about 1.0 x 10 6 to about 3.0 x 10 6 , for example about 2.0 x 10 6 , and an MWD of 20.0 or less, e.g., of from about 2.0 to about 20.0, preferably about 4.0 to about 15.0.
  • PE3 can be, e.g., an ethylene homopolymer or an ethylene/alpha-olefin copolymer containing 5.0 mol.% or less of one or more comonomers such as alpha-olefin, based on 100% by mole of the copolymer.
  • the comonomer can be, for example, one or more of, propylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene-1, vinyl acetate, methyl methacrylate, or styrene.
  • Such a polymer or copolymer can be produced using a Ziegler-Natta or a single-site catalyst, though this is not required.
  • Such a PE can have a melting point of 134degrees Celsius or more. The melting points of PE1 - PE3 can be determined using the methods disclosed in PCT Patent Publication No. WO 2008/140835, for example.
  • the PE includes an amount B 1 of PE1 and/or PE2 and an amount B 2 of PE3.
  • B 1 is in the range of from 60.0 wt.% to 96.0 wt.%
  • B 2 is in the range of from 0.0 wt.% to 20.0 wt.%, the B 1 and B 2 weight percents being based on the weight of the polymer in the membrane.
  • B 1 is in the range of from 69.5 wt.% to 90.5 wt.%, e.g., in the range of from 80.0 wt.% to 85.0 wt.%, based on the total polymer in the membrane.
  • B 2 is in the range of from 5.0 wt.% to 15.0 wt. %, e.g., in the range of from 9.75 wt.% to 15.25 wt.%, based on the total polymer in the membrane.
  • B 1 is in the range of from 79.0 wt.% to 95.0 wt.% and B 2 is in the range of from 0.0 wt.% to 16.0 wt.%.
  • the membrane Since it can be more difficult to produce a membrane having a meltdown temperature 145 degrees Celsius or more, e.g., 147 degrees Celsius or more, when B 2 is less than about 7.5 wt.%, in one embodiment, the membrane has a meltdown temperature of 145 degrees Celsius or more, e.g., 147 degrees Celsius or more, and has B 2 of 8.0 wt.% or more, such as 10.0 wt.% or more.
  • the polypropylene can be, e.g., polypropylene having an Mw of 5.0 x 10 5 or more, such as 6.0 x 10 5 or more, or, 7.5 x 10 5 or more, for example in the range of from about 0.8 x 10 6 to about 3.0 x 10 6 , such as in the range of from 0.9 x 10 6 to 2.0 x 10 6 .
  • the PP has a Tm of 160.0 degrees Celsius or more and a delta Hm of 80.0 J/g or more, e.g., 90.0 J/g or more, or, 100.0 J/g or more, such as in the range of from 110 J/g to 120 J/g.
  • the PP has an MWD or less 20.0, e.g., in the range of from about 1.5 to about 10.0, such as in the range of from about 2.0 to about 8.5.
  • the PP is a copolymer (random or block) of propylene and 5.0 mol.% or less of a comonomer, the comonomer being, e.g., one or more alpha-olefins such as ethylene, butene-1, pentene-1, hexene-1, 4-methylpentene-1, octene-1, vinyl acetate, methyl methacrylate, and styrene, etc.; or diolefins such as butadiene, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene, etc.
  • the PP is isotactic polypropylene.
  • the PP has (a) a meso pentad fraction about 90.0 mol.% or more of mmmm pentads, optionally 96.0 mol.% or more of mmmm pentads, preferably 96.0 mol.% or more of mmmm pentads; and (b) has an amount of stereo defects of about 50.0 or less per 1.0 x 10 4 carbon atoms, e.g., about 20 or less per 1.0 x 10 4 carbon atoms, or about 10.0 or less per 1.0 x 10 4 carbon atoms, such as about 5.0 or less per 1.0 x 10 4 carbon atoms.
  • the PP has one or more of the following properties: (i) a Tm of 162.0 degrees Celsius or more; (ii) an elongational viscosity of about 5.0 x 10 4 Pa sec or more at a temperature of 230 degrees Celsius and a strain rate of 25 sec -1 ; (iii) a Trouton's ratio of about 15 or more when measured at a temperature of about 230 degrees Celsius and a strain rate of 25 sec -1 ; (iv) a Melt Flow Rate ("MFR"; ASTM D-1238-95 Condition L at 230 degrees Celsius and 2.16 kg) of about 0.1 dg/min or less, e.g., about 0.01 dg/min or less (i.e., a value is low enough that the MFR is essentially not measurable); or (v) an amount extractable species (extractable by contacting the PP with boiling xylene) of 0.5 wt.% or less, e.g., 0.2 wt.%
  • the PP is an isotactic PP having an Mw in the range of from about 0.9 x 10 6 to about 2.0 x 10 6 , an MWD of 8.5 or less, e.g., in the range of from 2.0 to 8.5, e.g., in the range of from 2.5 to 6.0, and a delta Hm of 90.0 J/g or more.
  • such a PP has a meso pentad fraction 94.0 mol.% or more of mmmm pentads, an amount of stereo defects of about 5.0 or less per 1.0 x 10 4 carbon atoms, and a Tm of 162.0 degrees Celsius or more.
  • the PP comprises 90.0 wt.% or more isotactic polypropylene having an Mw of 6.0 x 10 5 or more, an MWD of 8.5 or less and a delta Hm of 90.0 J/g or more, the weight percent being based on the weight of the PP.
  • Tm can be determined from differential scanning calorimetric (DSC) data obtained using a PerkinElmer Instrument, model Pyris 1 DSC. Samples weighing approximately 5.5-6.5 mg are sealed in aluminum sample pans. The DSC data are recorded by first heating the sample to 230 degrees Celsius at a rate of 10 degrees Celsius /minute, called first melt (no data recorded). The sample is kept at 230 degrees Celsius for 10 minutes before a cooling-heating cycle is applied.
  • DSC differential scanning calorimetric
  • the sample is then cooled from about 230 degrees Celsius to about 25 degrees Celsius at a rate of 10 degrees Celsius/minute, called “crystallization", then kept at 25 degrees Celsius for 10 minutes, and then heated to 230 degrees Celsius at a rate of 10 degrees Celsius/minute, called (“second melt”).
  • the thermal events in both crystallization and second melt are recorded.
  • the melting temperature (T m ) is the peak temperature of the second melting curve and the crystallization temperature (T c ) is the peak temperature of the crystallization peak.
  • inorganic species such as species containing silicon and/or aluminum atoms, e.g., silica and/or alumina
  • heat-resistant polymers such as those described in PCT Publications WO 2007/132942 and WO 2008/016174 (both of which are incorporated by reference herein in their entirety) can be present in the membrane.
  • the membrane contains or less 1.0 wt.% of such materials, based on the weight of the membrane.
  • a small amount of diluent or other species, e.g., as processing aids, can also be present in the membrane, generally in amounts less than 1.0 wt.% based on the weight of the membrane.
  • the final microporous membrane When the microporous membrane is produced by extrusion, the final microporous membrane generally comprises the polymer used to produce the extrudate.
  • a small amount of diluent or other species introduced during processing can also be present, generally in amounts less than 1.0 wt.% based on the weight of the membrane.
  • a small amount of polymer molecular weight degradation might occur during processing, but this is acceptable.
  • molecular weight degradation during processing if any, causes the value of MWD of the polymer in the membrane to differ from the MWD of the polymer used to produce the membrane (e.g., before extrusion) by no more than, e.g., about 10%, or no more than about 1%, or no more than about 0.1%.
  • Polymer Mw and MWD can be determined using a High Temperature Size Exclusion Chromatograph, or "SEC”, (GPC PL 220, Polymer Laboratories), equipped with a differential refractive index detector (DRI). The measurement is made in accordance with the procedure disclosed in "Macromolecules, Vol. 34, No. 19, pp. 6812-6820 (2001)”. Three PLgel Mixed-B columns (available from Polymer Laboratories) are used for the Mw and MWD determination.
  • the nominal flow rate is 0.5 cm 3 /min; the nominal injection volume is 300 micro L; and the transfer lines, columns, and the DRI detector are contained in an oven maintained at 145 degrees Celsius.
  • the nominal flow rate is 1.0 cm 3 /min; the nominal injection volume is 300 micro L; and the transfer lines, columns, and the DRI detector are contained in an oven maintained at 160 degrees Celsius.
  • the GPC solvent used is filtered Aldrich reagent grade 1,2,4-Trichlorobenzene (TCB) containing approximately 1000 ppm of butylated hydroxy toluene (BHT).
  • TCB 1,2,4-Trichlorobenzene
  • BHT butylated hydroxy toluene
  • Polymer solutions are prepared by placing dry polymer in a glass container, adding the desired amount of the TCB solvent, and then heating the mixture at 160 degrees Celsius with continuous agitation for about 2 hours. The concentration of polymer solution is 0.25 to 0.75mg/ml. Sample solutions are filtered off-line before injecting to GPC with 2 micrometer filter using a model SP260 Sample Prep Station (available from Polymer Laboratories).
  • the separation efficiency of the column set is calibrated with a calibration curve generated using seventeen individual polystyrene standards ranging in Mp ("Mp" being defined as the peak in Mw) from about 580 to about 10,000,000.
  • Mp being defined as the peak in Mw
  • the polystyrene standards are obtained from Polymer Laboratories (Amherst, MA).
  • a calibration curve (log Mp vs. retention volume) is generated by recording the retention volume at the peak in the DRI signal for each PS standard and fitting this data set to a 2nd-order polynomial. Samples are analyzed using IGOR Pro, available from Wave Metrics, Inc. Membranes
  • the invention relates to a membrane comprising 79.0 wt.% to 86.0 wt.% of PE1, 9.0 wt.% to 16.0 wt.% of PE3, and 4.0 wt.% to 6.0 wt.% of PP, wherein (i) the PE1 has an Mw in the range of from about 4.0 x 10 5 to about 6.0 x 10 5 , an MWD of from about 3.0 to about 10.0, an amount of terminal unsaturation of 0.14 or less per 1.0 x 10 4 carbon atoms, and a melting point of 132 degrees Celsius or more; (ii) the PE3 has an Mw in the range of from about 1.0 x 10 6 to about 3.0 x 10 6 , an MWD in the range of from about 4.0 to about 15.0, and a melting point of 134 degrees Celsius or more; (iii) the PP is an isotactic PP having an Mw in the range of from about 0.9 x 10 6 to about 2.0
  • the membrane is microporous; and (v) the membrane has a thickness of 12.0 micrometer or less, such as 8.0 micrometer or less.
  • the membrane is a monolayer membrane.
  • the membrane contains 1.0 wt.% or less of PE2 based on the weight of the membrane.
  • Such a membrane has, e.g., a meltdown temperature of 145.0 degrees Celsius or more, e.g., 148.0 degrees Celsius or more, such as 150.0 degrees Celsius or more; a Normalized Electrolyte Affinity of 0.24 seconds/micrometer or less, e.g., 0.20 seconds/micrometer or less, such as 0.18 seconds/micrometer or less; and a Normalized Pin puncture Strength of 2.85 x 10 2 mN/micrometer or more, e.g., 2.90 x 10 2 mN/micrometer or more.
  • the membrane has a thickness of 9.0 micrometer or less, a Normalized Pin Puncture Strength of 2.85 x 10 2 mN/ micrometer or more, an NEA of 0.18 seconds/micrometer or less, and a porosity of 35.0% or more.
  • the combined weight of the PE1, PE2, and PP is 95.0 wt.% or more, e.g., 98.0 wt.% or more, such as 99.0 wt.% or more of the weight of the membrane.
  • the invention relates to a membrane comprising 79.0 wt.% to 86.0 wt.% of PE2, 9.0 wt.% to 16.0 wt.% of PE3, and 4.0 wt.% to 6.0 wt.% of PP, wherein (i) the PE2 has an Mw in the range of from about 3.0 x 10 5 to about 8.0 x 10 5 , an MWD in the range of from about 4 to about 15, a terminal unsaturation amount of 0.20 or more per 1.0 x 10 4 carbon atoms, and a melting point of 132 degrees Celsius or more; (ii) the PE3 has an Mw in the range of from about 1.0 x 10 6 to about 3.0 x 10 6 , an MWD in the range of from about 4.0 to about 15.0, and a melting point of 134 degrees Celsius or more; (iii) the PP is an isotactic PP having an Mw in the range of from about 0.9 x 10 6 to about 2.0
  • the membrane is microporous; and (v) the membrane has a thickness of 12.0 micrometer or less, such as 8.0 micrometer.
  • the weight percents are based on the weight of the membrane.
  • the membrane contains 1.0 wt.% or less of PE1 based on the weight of the membrane.
  • Such a membrane has a meltdown temperature of 145.0 degrees Celsius or more, e.g., 150.0 degrees Celsius or more, and a Normalized Electrolyte Affinity of 0.16 seconds/micrometer or less, e.g., 0.14 seconds/micrometer or less, and a normalized pin puncture strength less than 2.90 x 10 2 mN/micrometer.
  • the membrane is a monolayer membrane.
  • the combined weight of the PE1, PE2, and PP is 95.0 wt.% or more, e.g., 98.0 wt.% or more, such as 99.0 wt.% or more of the weight of the membrane.
  • the invention encompasses the use of the membranes of any preceding embodiment as battery separator film in lithium ion polymer batteries, particularly secondary lithium ion polymer batteries. While not wishing to be bound by any theory or model, it is believed that substituting PE2 for PE1 while keeping the relative amounts of PP and PE3 in the membrane substantially constant leads to an increase in the membrane's affinity for polymer electrolyte but decreases the membrane's strength.
  • the microporous membranes can be produced by combining a first polymer (i.e. PE) and a second polymer (i.e., PP) (e.g., by dry blending or melt mixing) with diluent and optional constituents such as inorganic fillers to form a mixture and then extruding the mixture to form an extrudate. At least a portion of the diluent is removed from the extrudate to form the microporous membrane.
  • PE first polymer
  • PP i.e., polypropylene
  • a blend of PE1 and/or PE2 with PE3 and PP can be combined with diluent such as liquid paraffin to form a mixture, with the mixture being extruded and processed to form a monolayer membrane having a thickness of 12.0 micrometer or less. Additional layers can be applied to the extrudate, if desired, e.g., to provide the finished membrane with a low shutdown functionality.
  • monolayer extrudates or monolayer microporous membranes can be laminated or coextruded to form multilayered membranes.
  • the process for producing the membrane comprises stretching the extrudate in at least one direction before diluent removal. In these or other embodiments, the process comprises stretching the membrane in at least one direction after diluent removal.
  • the process for producing the membrane optionally further comprises steps for, e.g., removing at least a portion of any remaining volatile species from the membrane at any time after diluent removal, subjecting the membrane to a thermal treatment (such as heat setting or annealing) before or after diluent removal.
  • a thermal treatment such as heat setting or annealing
  • Optional steps for solvent treatment, heat setting, cross-linking with ionizing radiation, and hydrophilic treatment, etc., as described in PCT Publication WO 2008/016174 can be conducted, if desired. Neither the number nor order of the optional steps is critical.
  • first and second polymers are introduced with one or more diluents and mixed to form a polymer-diluent mixture.
  • the first and second polymers can be combined to form a polymer blend, and the blend is combined with diluent (which can be a mixture of diluents, e.g., a solvent mixture) to produce a polymer-diluent mixture.
  • diluent which can be a mixture of diluents, e.g., a solvent mixture
  • Mixing can be conducted in, e.g., an extruder such as a reaction extruder.
  • extruders include, without limitation, twin-screw extruders, ring extruders, and planetary extruders. Practice of the invention is not limited to the type of extruder employed.
  • Optional species can be included in the polymer-diluent mixture, e.g., fillers, antioxidants, stabilizers, and/or heat-resistant polymers. The type and amounts of these optional species can be the same as described in PCT Publications WO 2007/132942, WO 2008/016174, and WO 2008/140835, all of which are incorporated by reference herein in their entirety.
  • the diluent is generally compatible with the polymers used to produce the extrudate.
  • the diluent can be any species or combination of species capable of forming a single phase in conjunction with the resin at the extrusion temperature.
  • the diluent include one or more of aliphatic or cyclic hydrocarbon such as nonane, decane, decalin and paraffin oil, and phthalic acid ester such as dibutyl phthalate and dioctyl phthalate. Paraffin oil with a kinetic viscosity of 20-200 cSt at 40degrees Celsius can be used, for example.
  • the diluent can be the same as those described in U.S. Patent Publication Nos. 2008/0057388 and 2008/0057389, both of which are incorporated by reference in their entirety.
  • the polymer blend in the polymer-diluent mixture comprises an amount A 1 of the first polymer (e.g., PE1 and PE3) and an amount A 2 of the second polymer (e.g., PP).
  • a 1 is 1.0 wt.% or more, e.g., in the range of from 80.0 wt.% to 96.0 wt.%
  • a 2 is in the range of from 4.0 wt.% to 20.0 wt.%, the A 1 and A 2 weight percents being based on the weight of the polymer in the mixture.
  • a 1 is in the range of from 84.5 wt.% to 95.5 wt.%, e.g., in the range of from 94.75 wt.% to 95.25 wt.%.
  • a 2 is in the range of from 4.5 wt.% to 15.5, e.g., in the range of from 4.75 to 5.25 wt.%, based on the total weight of polymer in the mixture.
  • the polymer-diluent mixture comprises 45.0 wt.% or less polymer based on the weight of the mixture, e.g., in the range of from 30.0 wt.% to 40.0 wt.%, based on the total weight of polymer in the mixture. The balance of the mixture can be diluent.
  • the amount A 1 of PE in the polymer-diluent mixture may include an amount B 1 of PE1 and/or PE2 and an amount B 2 of PE3.
  • B 1 is in the range of from 60.0 wt.% to 96.0 wt.%
  • B 2 is in the range of from 0.0 wt.% to 20.0 wt.%, the B 1 and B 2 weight percents being based on the weight of the polymer in the mixture.
  • B 1 is in the range of from 69.5 wt.% to 90.5 wt.%, e.g., in the range of from 80.0 wt.% to 85.0 wt.%, based on the total polymer in the mixture.
  • B 2 is in the range of from 5.0 wt.% to 15.0, e.g., in the range of from 9.75 wt.% to 15.25 wt%, based on the total polymer in the mixture.
  • the polymer-diluent mixture during extrusion is exposed to a temperature in the range of 140 degrees Celsius to 250 degrees Celsius, e.g., 210 degrees Celsius to 230 degrees Celsius.
  • the polymer-diluent mixture is conducted from an extruder through a die to produce the extrudate.
  • the extrudate should have an appropriate thickness to produce, after the processing steps, a final membrane having the desired thickness (generally 12.0 micrometer or less).
  • the extrudate can have a thickness in the range of about 1.0 micrometer to about 10.0 micrometer, or about 3.0 micrometer to about 8.0 micrometer.
  • the finished membrane has a final membrane thickness (after processing) of 12.0 micrometer or less, e.g., 10.0 micrometer or less.
  • Extrusion is generally conducted with the polymer-diluent mixture in the molten state.
  • the die lip is generally heated to an elevated temperature, e.g., in the range of 180 degrees Celsius to 240 degrees Celsius.
  • elevated temperature e.g., in the range of 180 degrees Celsius to 240 degrees Celsius.
  • Suitable process conditions for accomplishing the extrusion are disclosed in PCT Publications WO 2007/132942 and WO 2008/016174.
  • the extrudate can be exposed to a temperature in the range of about 10 degrees Celsius to about 45 degrees Celsius to form a cooled extrudate.
  • Cooling rate is not particularly critical.
  • the extrudate can be cooled at a cooling rate of at least about 30 degrees Celsius/minute until the temperature of the extrudate (the cooled temperature) is approximately equal to the extrudate's gelation temperature (or lower).
  • Process conditions for cooling can be the same as those disclosed in PCT Publications No. WO 2007/132942, WO 2008/016174, and WO 2008/140835, for example. Stretching the Extrudate (Upstream Stretching)
  • the extrudate or cooled extrudate can be stretched in at least one direction (called “upstream stretching” or “wet stretching”), e.g., in a planar direction such as MD or TD. It is believed that such stretching results in at least some orientation of the polymer in the extrudate. This orientation is referred to as "upstream” orientation.
  • the extrudate can be stretched by, for example, a tenter method, a roll method, an inflation method or a combination thereof, as described in PCT Publication No. WO 2008/016174, for example.
  • the stretching may be conducted monoaxially or biaxially; in certain embodiments, the extrudate is biaxially stretched.
  • any of simultaneous biaxial stretching, sequential stretching or multi-stage stretching can be used; in certain embodiments, the extrudate is simultaneously biaxially stretched.
  • the amount of magnification need not be the same in each stretching direction.
  • the stretching magnification can be, for example, 2 fold or more, e.g., 3 to 30 fold in the case of monoaxial stretching.
  • the stretching magnification can be, for example, 3 fold or more in any direction, namely 9 fold or more, such as 16 fold or more, e.g., 25 fold or more, in area magnification.
  • An example for this stretching step would include stretching from about 9 fold to about 49 fold in area magnification. Again, the amount of stretching in either direction need not be the same.
  • the magnification factor operates multiplicatively on film size. For example, a film having an initial width (TD) of 2.0 cm that is stretched in TD to a magnification factor of 4 fold will have a final width of 8.0 cm.
  • the stretching can be conducted while exposing the extrudate to a temperature (the upstream stretching temperature) in the range of from about the Tcd temperature to Tm, where Tcd and Tm are defined as the crystal dispersion temperature and melting point of the PE having the lowest melting point among the polyethylenes used to produce the extrudate (generally the PE such as PE1 or PE3).
  • the crystal dispersion temperature is determined by measuring the temperature characteristics of dynamic viscoelasticity according to ASTM D 4065.
  • Tcd is in the range of about 90 degrees Celsius to about 100 degrees Celsius
  • the stretching temperature can be from 90.0 degrees Celsius to 122.0 degrees Celsius; e.g., from 108.0 degrees Celsius to 116.0 degrees Celsius, such as from 110.0 degrees Celsius to 114.0 degrees Celsius.
  • the sample e.g., the extrudate, dried extrudate, membrane, etc.
  • this exposure can be accomplished by heating air and then conveying the heated air into proximity with the sample.
  • the temperature of the heated air which is generally controlled at a set point equal to the desired temperature, is then conducted toward the sample through a plenum for example.
  • Other methods for exposing the sample to an elevated temperature including conventional methods such as exposing the sample to a heated surface, infra-red heating in an oven, etc., can be used with or instead of heated air.
  • At least a portion of the diluent is removed (or displaced) from the stretched extrudate to form a dried membrane.
  • a displacing (or “washing") solvent can be used to remove (wash away, or displace) the diluent, as described in PCT Publication No. WO 2008/016174, for example.
  • any remaining volatile species e.g., washing solvent
  • Any method capable of removing the washing solvent can be used, including conventional methods such as heat-drying, wind-drying (moving air), etc.
  • Process conditions for removing volatile species such as washing solvent can be the same as those disclosed in PCT Publication No. WO 2008/016174, for example.
  • Optional Stretching the Membrane Downstream Stretching
  • the dried membrane can be stretched (called “downstream stretching” or “dry stretching” since at least a portion of the diluent has been removed or displaced) in at least one direction, e.g., MD and/or TD. It is believed that such stretching results in at least some orientation of the polymer in the membrane. This orientation is referred to as downstream orientation.
  • the dried membrane Before downstream stretching, the dried membrane has an initial size in MD (a first dry length) and an initial size in TD (a first dry width).
  • first dry width refers to the size of the dried membrane in TD prior to the start of dry stretching.
  • first dry length refers to the size of the dried membrane in MD prior to the start of dry stretching.
  • Tenter stretching equipment of the kind described in WO 2008/016174 can be used, for example.
  • the dried membrane can be stretched in MD from the first dry length to a second dry length that is larger than the first dry length by a magnification factor (the "MD dry stretching magnification factor") in the range of from about 1.0 to about 1.6, e.g., in the range of from about 1.1 to 1.5.
  • the TD dry stretching magnification factor is the MD dry stretching magnification factor or more.
  • the TD dry stretching magnification factor can be in the range of from about 1.1 to about 1.6, e.g., from about 1.1 to 1.5.
  • the dry stretching can be sequential or simultaneous in MD and TD. When biaxial dry stretching is used, the dry stretching can be simultaneous in MD and TD or sequential. When the dry stretching is sequential, generally MD stretching is conducted first, followed by TD stretching.
  • the processing steps that produce films having a desired thickness are devoid of any step of dry stretching.
  • the processing steps include dry stretching to a magnification factor of 1.1 or less, in other embodiments 1.08 or less, in other embodiments 1.05 or less, and in other embodiments 1.03 or less.
  • the dry stretching can be conducted while exposing the dried membrane to a temperature (the downstream stretching temperature) of Tm or less, e.g., in the range of from about Tcd-20 degrees Celsius to Tm.
  • the stretching temperature is conducted with the membrane exposed to a temperature in the range of from about 70.0 degrees Celsius to about 135.0 degrees Celsius, for example from about 110.0 degrees Celsius to about 132.0 degrees Celsius, such as from about 120.0 degrees Celsius to about 130.0 degrees Celsius.
  • the MD dry stretching magnification is about 1.0; the TD dry stretching magnification is 1.6 or less, e.g. in the range of from about 1.05 to about 1.5, such as from about 1.1 to 1.5; and the dry stretching is conducted while the membrane is exposed to a temperature in the range of from about 120.0 degrees Celsius to about 130.0 degrees Celsius.
  • the dry stretching rate is not critical.
  • the dry stretching rate is 1 %/second or more in the stretching direction (MD or TD), and the rate can be independently selected for MD and TD stretching.
  • the stretching rate is 2 %/second or more, e.g., 3 %/second or more, such as 10 %/second or more.
  • the stretching rate is in the range of from 2 %/second to 25 %/second.
  • the upper limit of the stretching rate may be 50%/second to prevent rupture of the membrane. Controlled Reduction of the Membrane's Width
  • the dried membrane optionally can be subjected to a controlled reduction in width from the second dry width to a third dry width, the third dry width being in the range of from 0.9 times the first dry width to about 1.5 times larger than the first dry width.
  • the second dry width is in the range of from 1.25 to 1.35 of the first dry width and the third dry width is in the range of from 0.95 to 1.05 of the first dry width.
  • the width reduction generally conducted while the membrane is exposed to a temperature of Tcd - 30 degrees Celsius or more, but no greater than Tm, e.g., with the membrane exposed to a temperature in the range of from about 70.0 degrees Celsius to about 135.0 degrees Celsius, for example from about 110.0 degrees Celsius to about 132.0 degrees Celsius, such as from about 120.0 degrees Celsius to about 130.0 degrees Celsius.
  • the temperature during controlled width reduction can be the same as the downstream stretching temperature, this is not required, and in one embodiment the temperature to which the membrane is exposed during controlled width reduction is 1.01 times or more the downstream stretching temperature, e.g., in the range of 1.05 times to 1.1 times.
  • the decreasing of the membrane's width is conducted while the membrane is exposed to a temperature that 130.0 degrees Celsius or less, the third dry width is in the range of from 0.95 to 1.05 of the first dry width.
  • the membrane is thermally treated (heat-set) at least once following diluent removal, e.g., after dry stretching, the controlled width reduction, or both. It is believed that heat-setting stabilizes crystals and makes uniform lamellas in the membrane.
  • the heat setting is conducted while exposing the membrane to a temperature in the range Tcd to Tm, e.g., in the range of from about 70.0 degrees Celsius to about 135.0 degrees Celsius, for example from about 110.0 degrees Celsius to about 132.0 degrees Celsius, such as from about 120.0 degrees Celsius to about 130.0 degrees Celsius.
  • the heat set temperature can be the same as the downstream stretching temperature, this is not required.
  • the temperature to which the membrane is exposed during heat setting is 1.01 times or more the downstream stretching temperature, e.g., in the range of 1.05 times to 1.1 times.
  • the heat setting is conducted for a time sufficient to form uniform lamellas in the membrane, e.g., a time of 1,000 seconds or less, e.g., in the range of 1 to 600 seconds.
  • the heat setting is operated under conventional heat-set "thermal fixation" conditions.
  • the term “thermal fixation” refers to heat-setting carried out while maintaining the length and width of the membrane substantially constant, e.g., by holding the membrane's perimeter with tenter clips during the heat setting.
  • an annealing treatment can be conducted after the heat-set step.
  • the annealing is a heat treatment with no load applied to the membrane, and can be conducted by using, e.g., a heating chamber with a belt conveyer or an air-floating-type heating chamber.
  • the annealing may also be conducted continuously after the heat-setting with the tenter slackened.
  • the membrane can be exposed to a temperature in the range of Tm or lower, e.g., in the range from about 60 degrees Celsius to about Tm -5 degrees Celsius. Annealing is believed to provide the microporous membrane with improved permeability and strength.
  • Optional heated roller, hot solvent, crosslinking, hydrophilizing, and coating treatments can be conducted, if desired, e.g., as described in PCT Publication No. WO 2008/016174.
  • the membrane is microporous membrane that is permeable to liquid (aqueous and non-aqueous) at atmospheric pressure.
  • the membrane can be used as a battery separator, filtration membrane, etc.
  • the membrane is particularly useful as a BSF for a secondary battery, such as a nickel-hydrogen battery, nickel-cadmium battery, nickel-zinc battery, silver-zinc battery, lithium-ion battery, lithium-ion polymer battery, etc.
  • the invention relates to lithium-ion secondary batteries containing BSF comprising membrane. Such batteries are described in PCT Patent Publication WO 2008/016174, which is incorporated herein by reference in its entirety.
  • the microporous membrane is a monolayer that is useful as a BSF for polymer batteries such as lithium-ion polymer batteries.
  • polymer electrolyte is used in its ordinary sense to refer to the electrolyte within a polymer battery.
  • polymer batteries include an electrolyte, such as a lithium ion, that is dispersed, suspended, or dissolved in a polymer medium.
  • electrolyte affinity or permeability refers to the ability of the polymer medium and/or electrolyte, such as lithium ion, to permeate through the membrane.
  • the membrane can have one or more of the following properties. Thickness
  • the thickness of the final membrane is 12.0 micrometer or less, such as 10.0 micrometer or less, e.g., in the range of about 1.0 micrometer to about 10.0 micrometer.
  • a monolayer membrane can have a thickness in the range of about 4.5 micrometer to about 9.5 micrometer.
  • the membrane's thickness can be measured, e.g., by a contact thickness meter at 1 cm longitudinal intervals over the width of 10 cm, and then averaged to yield the membrane thickness.
  • Thickness meters such as a Model RC-1 Rotary Caliper, available from Maysun, Inc., 746-3 Gokanjima, Fuji City, Shizuoka, Japan 416-0946 or a "Litematic" available from Mitsutoyo Corporation, are suitable.
  • Non-contact thickness measurement methods are also suitable, e.g., optical thickness measurement methods.
  • the membrane's porosity is 20.0% or more, e.g., 31.0 % or more, such as 35.0 % or more.
  • the membrane's porosity can be in the range of 20.0% to 80.0%, such as 36.0% to 40.0%. Normalized Air Permeability
  • the membrane has a normalized air permeability is 50.0 seconds/100 cm 3 /micrometer or less, e.g., in the range of from about 10.0 seconds/100 cm 3 /micrometer to about 45.0 seconds/100 cm 3 /micrometer, such as from about 15.0 seconds/100 cm 3 /micrometer to about 40.0 seconds/100 cm 3 /micrometer. Since the air permeability value is normalized to the value for an equivalent membrane having a film thickness of 1.0 micrometer, the membrane's air permeability value is expressed in units of "seconds/100 cm 3 /micrometer ".
  • the membrane's pin puncture strength is expressed as the pin puncture strength of an equivalent membrane having a thickness of 1.0 micrometer and a porosity of 30% and has the units [mN/micrometer].
  • Pin puncture strength is defined as the maximum load measured at ambient temperature when the membrane having a thickness of T 1 is pricked with a needle of 1 mm in diameter with a spherical end surface (radius R of curvature: 0.5 mm) at a speed of 2mm/second.
  • the membrane's normalized pin puncture strength is 2.50 x 10 2 mN/micrometer or more, e.g., 2.90 x 10 2 mN/micrometer or more.
  • the membrane's normalized pin puncture strength is 3.0 x 10 2 mN/micrometer or more, such as in the range of 3.05 x 10 2 mN/micrometer to 4.5 x 10 2 mN/micrometer.
  • the microporous membrane's shutdown temperature is measured by the method disclosed in PCT Publication No. WO2007/052663, which is incorporated by reference herein in its entirety. According to this method, the microporous membrane is exposed to an increasing temperature (5 degrees Celsius/minute) starting at 25 degrees Celsius while measuring the membrane's air permeability.
  • the microporous membrane's shutdown temperature is defined as the temperature at which the microporous membrane's air permeability (Gurley Value) first exceeds 1.0 x 10 5 secs./100 cm 3 .
  • the microporous membrane's air permeability is measured according to JIS P 8117 using an air permeability meter (EGO-1T available from Asahi Seiko Co., Ltd.).
  • the shut down temperature is or less 136 degrees Celsius, such as in the range of 132.5 degrees Celsius to 134.5 degrees Celsius. Meltdown temperature
  • the microporous membrane's shutdown temperature is measured using a procedure similar to the measurement of shutdown temperature. According to this method, the microporous membrane is exposed to an increasing temperature (5 degrees Celsius/minute) starting at 25 degrees Celsius while measuring the membrane's air permeability, to a temperature exceeding the membrane's Shutdown temperature. The membrane heating continues, and the microporous membrane's Meltdown temperature is defined as the temperature at which the microporous membrane's air permeability (Gurley Value) first decreases to a value of 1.0 x 10 5 secs./100 cm 3 . The microporous membrane's air permeability is measured according to JIS P 8117 using an air permeability meter (EGO-1T available from Asahi Seiko Co., Ltd.).
  • EGO-1T air permeability meter
  • the Meltdown temperature of the membranes of present invention is 145.0 degrees Celsius or more, e.g., 150.0 degrees Celsius or more, such as 160.0degrees Celsius or more. In an embodiment the Meltdown temperature is in the range of 146.0 degrees Celsius to 170.0 degrees Celsius, such as in the range of 150.0 degrees Celsius to 165 degrees Celsius. 105 degrees Celsius Heat Shrinkage
  • the membrane has a heat shrinkage at 105 degrees Celsius in at least one planar direction (e.g., MD or TD) of 10.0% e.g. or less, 6.0% or more, such as in the range of from 1.0% to 5.0%.
  • the membrane's shrinkage at 105.0 degrees Celsius in MD and TD is measured as follows: (i) measure the size of a test piece of microporous membrane at ambient temperature in both the MD and TD; (ii) equilibrate the test piece of the microporous membrane at a temperature of 105 degrees Celsius for 8 hours with no applied load; and then (iii) measure the size of the membrane in both the MD and TD.
  • the heat (or "thermal") shrinkage in MD and TD can be obtained by dividing the result of measurement (i) by the result of measurement and (ii) expressing the resulting quotient as a percent.
  • the membrane has an MD and TD tensile strengths of each 1.4 x 10 5 kPa or more, e.g., in the range of 1.5 x 10 5 kPa to 2.0 x 10 5 kPa.
  • Tensile strength is measured in MD and TD according to ASTM D-882A.
  • a 50 mm x 50 mm (thickness is 12.0 micrometer or less) membrane sample is prepared and laid flat on a glass substrate having a larger area than that of the film.
  • the film is illuminated from above using visible light, and is opaque at the start of the measurement.
  • a 500.0 micro L droplet of propylene carbonate (purity is 99 vol % or more) is applied to the surface of the film with the membrane at 25 degrees Celsius, +/- 3 degrees Celsius.
  • the membrane's electrolyte affinity (“EA”) is defined as the average elapsed time from the droplet's initial contact with the film to the time when the film becomes transparent. The measurement is repeated five times to obtain the average value.
  • EA Electrolyte Affinity
  • EA Average membrane thickness in micrometer
  • NEA has the units of [seconds/micrometer].
  • the membrane has an NEA of 5.0 seconds/micrometer or less, such as 2.5 seconds/micrometer or less, e.g., in the range of 0.1 seconds/ micrometer to 0.9 seconds/micrometer.
  • a polymer-diluent mixture is prepared as follows by combining diluent and a polymer blend of two polyethylenes, PE1 and PE3 and PP.
  • the polymer blend comprises (a) 90.0 wt.% of PE having an Mw of 5.6 x 10 5 , an MWD of 4.0, an amount of terminal unsaturation of 0.14 or less per 1.0 x 10 4 carbon atoms, and a Tm of 136.0 degrees Celsius (PE1), (b) 5.0 wt.% of PE having a Mw of 1.9 x 10 6 , an MWD of 5.1, and a Tm of 136.0 degrees Celsius (PE3), and (c) 5.0 wt.% of isotactic PP having an Mw of 5.3 x 10 5 and a delta Hm of about 80 J/g (PP2), the weight percents being based on the weight of the combined polymer.
  • 35.0 wt.% of the polymer blend is charged into a strong-blending double-screw extruder having an inner diameter of 58 mm and L/D of 42, and 65.0 wt.% liquid paraffin (50 cst at 40degrees Celsius) is supplied to the double-screw extruder via a side feeder.
  • Mixing is conducted at 220 degrees Celsius and 320 rpm to produce the polymer-diluent mixture, the weight percents being based on the weight of the polymer-diluent mixture.
  • the polymer-diluent mixture is conducted from the extruder to a sheet-forming die, to form an extrudate (in the form of a sheet).
  • the die temperature is about 210 degrees Celsius (or as specifically set forth in the Table 1).
  • the extrudate is cooled by contact with cooling rollers controlled at 20 degrees Celsius.
  • the cooled extrudate is simultaneously biaxially stretched (upstream stretching) at about 112.5 degrees Celsius (or as specifically set forth in the Table) to a magnification of 5 fold in both MD and TD by a tenter-stretching machine.
  • the stretched three-layer gel-like sheet is then immersed in a bath of methylene chloride controlled at 25 degrees Celsius to remove liquid paraffin to an amount of 1.0 wt.
  • the membrane is then dried by air flow at room temperature. While holding the size of the membrane substantially constant, the membrane is then heat-set at 128.8 degrees Celsius (or as provided in the Table) for 10 minutes to produce the final microporous membrane. Selected starting materials, process conditions, and membrane properties are set out in Table 1.
  • Example 1 is repeated except as noted in Table 1.
  • Starting materials and process conditions are the same as are used in Example 1, except as noted in the Table.
  • PP1 may be replaced by a polypropylene having an Mw of 1.1 x 10 6 and a delta Hm of 114 J/g (PP1);
  • PE1 may be replaced by a PE having an Mw of 7.46 x 10 5 , a Tm of 134.0 degrees Celsius, and a terminal unsaturation amount of 0.20 or more per 1.0 x 10 4 carbon atoms (PE2).
  • the membranes of Examples 4 and 5 are stretched downstream of diluent removal (downstream stretching) to a TD magnification factor of 1.4while exposed to a temperature of 130.2 degrees Celsius (Example 4) and 130.0 degrees Celsius (Example 5) respectively before heat setting. Discussion
  • Examples 1 - 5 show that relatively thin microporous membrane having useful meltdown temperature (e.g. 145.0 degrees Celsius or more) can be produced from PE and 4.0 wt.% or more PP based on the weight of the membrane.
  • Such membranes are useful as BSF in lithium ion batteries, such as lithium ion polymer batteries which utilize thin BSF.
  • the concentration of PP is increased, as shown by Example 5, the NEA is significantly increased.
  • the larger NEA value makes it more difficult to use the membrane as a BSF for polymer batteries.
  • the data shows that while a threshold amount of PP is necessary to achieve useful meltdown temperatures, increased PP loading has an undesirable impact on NEA.
  • Comparative Example 1 illustrates a BSF containing no PP.
  • Such membranes have a useful NEA, but also have a relatively low meltdown temperature, relatively low porosity, and relatively low Normalized Pin Puncture Strength.
  • microporous membranes of the present invention are suitable for use as battery separator film.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • General Chemical & Material Sciences (AREA)
  • Polymers & Plastics (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
  • Cell Separators (AREA)
  • Compositions Of Macromolecular Compounds (AREA)

Abstract

Cette invention concerne des membranes microporeuses ayant une température de fusion élevée et une affinité utile envers l'électrolyte. La production de ces membranes et leur utilisation en tant que films de séparation d'éléments de batterie sont également décrites.
PCT/JP2011/001398 2010-03-15 2011-03-10 Membranes microporeuses, leurs procédés de fabrication, et utilisation desdites membranes en tant que films de séparation d'éléments de batterie Ceased WO2011114664A1 (fr)

Priority Applications (3)

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CN201180012661.0A CN102884116B (zh) 2010-03-15 2011-03-10 微孔膜、该膜的生产方法、以及该膜作为电池隔膜的应用
JP2012533809A JP2013522379A (ja) 2010-03-15 2011-03-10 微多孔膜、これらの膜の作製方法、およびバッテリーセパレーターフィルムとしてのこれらの膜の使用
KR1020127023425A KR101841513B1 (ko) 2010-03-15 2011-03-10 미세다공막, 이들 막의 제조방법, 및 전지 세퍼레이터 필름으로서 이들 막의 사용

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KR101716249B1 (ko) * 2014-05-28 2017-03-14 도레이 배터리 세퍼레이터 필름 주식회사 폴리올레핀 미세 다공막 및 이의 제조 방법
JP2016030825A (ja) * 2014-07-30 2016-03-07 王子ホールディングス株式会社 二軸延伸ポリプロピレンフィルム
DE102019121854A1 (de) 2019-08-14 2021-02-18 Brückner Maschinenbau GmbH & Co. KG Anlage zur Herstellung einer Kunststoffschmelze und Verwendung einer solchen Anlage zur Herstellung einer Kunststoffschmelze für eine poröse Folie

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JP2006190507A (ja) * 2005-01-04 2006-07-20 Nitto Denko Corp リチウム二次電池
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WO2009038231A1 (fr) * 2007-09-20 2009-03-26 Tonen Chemical Corporation Membranes microporeuses, procédés de fabrication et utilisation de telles membranes

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JP4121846B2 (ja) * 2002-12-16 2008-07-23 東燃化学株式会社 ポリオレフィン微多孔膜及びその製造方法並びに用途
JP5073916B2 (ja) * 2004-02-10 2012-11-14 旭化成イーマテリアルズ株式会社 リチウムイオン電池用セパレーター用ポリオレフィン製微多孔膜
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JPH09241411A (ja) * 1996-03-13 1997-09-16 Nitto Denko Corp 多孔質膜及びその製造方法、並びにリチウムイオン２次電池
JP2006190507A (ja) * 2005-01-04 2006-07-20 Nitto Denko Corp リチウム二次電池
WO2007117005A1 (fr) * 2006-04-07 2007-10-18 Tonen Chemical Corporation Membrane microporeuse polyoléfinique multicouche, procédé de production de celle-ci, separateur d'accumulateur, et accumulateur
WO2009038231A1 (fr) * 2007-09-20 2009-03-26 Tonen Chemical Corporation Membranes microporeuses, procédés de fabrication et utilisation de telles membranes

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CN102884116B (zh) 2014-08-13
JP2013522379A (ja) 2013-06-13
JP6304149B2 (ja) 2018-04-04
KR101841513B1 (ko) 2018-03-23
CN102884116A (zh) 2013-01-16
KR20130016211A (ko) 2013-02-14
JP2015221904A (ja) 2015-12-10

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