CN102884116B

CN102884116B - Microporous membranes, methods for making these membranes, and the use of these membranes as battery separator films

Info

Publication number: CN102884116B
Application number: CN201180012661.0A
Authority: CN
Inventors: 菊池慎太郎; 松田洋一; 山田一博
Original assignee: Toray Battery Separator Film Co Ltd
Current assignee: Toray Industries Inc
Priority date: 2010-03-15
Filing date: 2011-03-10
Publication date: 2014-08-13
Anticipated expiration: 2031-03-10
Also published as: JP2013522379A; KR101841513B1; KR20130016211A; JP6304149B2; CN102884116A; JP2015221904A; WO2011114664A1

Abstract

The invention relates to microporous membranes having high meltdown temperature and useful electrolyte affinity. The invention also relates to the production of these membranes and the use of these membranes as battery separator film.

Description

The production method of microporous membrane, this film and this film are as the application of battery diaphragm

Technical field

The microporous membrane that the present invention relates to there is high melting temperature and the polymer dielectric of lithium ion polymer battery is had to practical affinity.The invention still further relates to the application as battery diaphragm of the production of this film and this film.

Background technology

Microporous membrane be suitable for do once with secondary cell in battery diaphragm (" BSF ").Described battery comprises lithium-ion secondary cell, lithium ion polymer secondary cell, nickel-hydrogen cell, nickel-cadmium cell, nickel-zinc cell, silver-zinc battery etc.

Microporous polymer membranes can be used as battery diaphragm (" BSF ") for for example lithium ion battery.Described film has the polymkeric substance mobility of increase under the battery temperature increasing, and this causes the remarkable reduction of Gas permeability.This effect is conducive to BSF, because the reduction of Gas permeability causes the decline of battery electrochemical activity under elevated temperature, so reduce in overcharged, the risk of battery failure under electric discharge or other high-temperature battery condition rapidly.Even because internal temperature of battery in the time that electrochemical activity declines also can continue to raise (for example, from temperature overshoot amount), thereby wish to increase the thermostability of film under elevated temperature further to reduce the risk of battery failure.This can for example, realize by comprise high-melting-point substances (polypropylene) in the polymkeric substance of film.Temperature contrast between polyethylene and polypropylene fusing point and physical incompatibility thereof are given containing the production of the film of two kinds of polymkeric substance and are caused difficulty, particularly in the time that described film is film.

Ionogen is wherein gel electrolyte or polymer dielectric, for example, the lithium ion battery (" lithium ion polymer battery ") that ionogen is contained in polymeric media is applied this BSF conventionally, and it contains and the polymkeric substance that contains electrolytical polymeric media compatible (for example it being had to affinity).The BSF of lithium ion polymer battery be usually used in for example cylindrically comparing and conventionally there is much smaller thickness with the BSF of square lithium ionization cell.

Summary of the invention

Therefore, wish to produce a kind of thinner polymeric film, this film has affinity to the polymkeric substance of the electrolyte medium as in polymer battery, and has dimensional stability under elevated temperature.

In one of embodiment, the present invention relates to a kind of film, Mw>=5.0 × 10 of the polyethylene that it contains at least 1.0 % by weight and 4.0 % by weight～20.0 % by weight ⁵, and the polypropylene of Δ Hm>=80.0J/g, the weight of described weight percentage based on film interpolymer; Wherein, described film is microporous membrane and its thickness≤12.0 μ m.

In another embodiment, the present invention relates to a kind of method of producing microporous membrane, it comprises the steps: step (1), and the mixture of thinner and polymkeric substance is extruded, and this polymkeric substance contains A ₁polyethylene and the A of amount ₂the polypropylene of amount, wherein, A ₁>=1.0 % by weight, for example, in the scope of 80.0 % by weight～96.0 % by weight, and A ₂in the scope of 4.0 % by weight～20.0 % by weight, described weight percentage is the polymer weight based in polymkeric substance-diluent mixture all; Step (2) stretches above-mentioned extrudate at least one in-plane; And step (3), at least a portion of removing thinner from stretching extrudate.

Film of the present invention has the temperature of fusion of improvement and enough ionogen avidities concurrently.

Embodiment

Observe the temperature of fusion that the microporous membrane that contains polyethylene, thickness≤12.0 μ m has 145.0 DEG C of < conventionally.Also observe in the time of polyethylene and polypropylene combination, these films have the temperature of fusion of increase, but the avidity of polymer dielectric is reduced.The present invention is at least in part based on this discovery,, when the polyethylene (based on the weight of film) of contain>=1.0 % by weight of described film and the weight-average molecular weight (" Mw ")>=5.0 × 10 of 4.0 % by weight～20.0 % by weight (based on the weight of this film) ⁵, and when the polypropylene miser of melting heat (" Δ Hm ")>=80.0J/g, the weight of described weight percentage based on film, can overcome above-mentioned difficult point.These films have the temperature of fusion of improvement, have again enough ionogen avidities, thereby are suitable for the BSF that makes lithium ion polymer battery.

With regard to this specification sheets and appended claim, term " polymer " " represent that this polymer contains the repeating unit from one or more of monomers containing a lot of high molecular compositions.Described polymer can be of different sizes, molecular structure, atom content etc.Term " polymer " " comprise the polymer of such as multipolymer, terpolymer etc." polyethylene " represents the polyolefine of contain >=50% (quantity) from the repeating unit of ethene, and preferably the repeating unit of Natene and/or at least 85% (quantity) is the polyethylene and ethylene copolymers of ethylene unit." polypropylene " represents to contain to be greater than the polyolefine of 50% (quantity) from the repeating unit of propylene, and preferably the repeating unit of homopolymer polypropylene and/or at least 85% (quantity) is the polypropylene copolymer of propylene units.Term " isotactic polyprophlene " represents that polyacrylic isotaxy five-tuple point rate is the polypropylene of following value: the mmmm five-tuple of >=about 50.0mol%, the mmmm five-tuple (based on the total mole number of isotactic polyprophlene) of preferably >=96.0mol%." microporous membrane " is a kind of film with micropore, wherein, the micropore amount of film >=90.0% (volume reference) is the hole of mean diameter within the scope of 0.01 μ m～10.0 μ m.As for the film of producing from extrudate, operating direction (" MD ") is defined as from the direction of die production extrudate.Laterally (" TD ") is defined as not only, but also with the thickness direction of extrudate vertical direction vertical with MD.MD and TD can represent the in-plane of film, and term " plane " herein represents when film is while being open and flat, are substantially positioned at the direction of the plane of this film.

The composition of microporous membrane

In one or more embodiment, the present invention relates to containing polyethylene and polyacrylic film, this film is microporous membrane and the thickness of have≤12.0 μ m.In one of embodiment, described microporous membrane contains a certain amount of (A ₁) polyethylene and a certain amount of (A ₂) polypropylene, these polyacrylic Mw>=5.0 × 10 ⁵, and Δ Hm>=80.0J/g.A ₁and A ₂can use the weight percentage of the weight based on film interpolymer to represent.For example, described weight percentage can be based on polyethylene in film and polyacrylic gross weight, for example, and A ₁+ A ₂=100 % by weight.In other embodiments, the weight that described weight percentage can be based on film, for example, may be substantially to contain (or only containing) polyethylene and polyacrylic situation when described film.

For example, in one or more embodiment, A ₁in the scope of 80.0 % by weight～96.0 % by weight, and A ₂in the scope of 4.0 % by weight～20.0 % by weight, based on A ₁and A ₂the A of gross weight ₁and A ₂weight percentage equal 100 % by weight.A ₁optionally in the scope of 84.5 % by weight～95.5 % by weight, for example, in the scope of 94.75 % by weight～95.25 % by weight.A ₂optionally in the scope of 4.5 % by weight～15.5 % by weight, for example, in the scope of 4.75 % by weight～5.25 % by weight.

Now polyethylene and polyacrylic selected embodiment will be described in more detail, but this description is not got rid of and is belonged to more other embodiment of wide region of the present invention.

Polyethylene

In specific embodiment, polyethylene (" PE ") can comprise poly mixture or reactor admixture, the mixture of for example two or more polyethylene kinds (" PE1 ", " PE2 ", " PE3 " etc. as mentioned below).For example, PE can comprise (i) PE (PE1) and/or the 2nd PE (PE2) and (ii) admixture of the 3rd PE (PE3).

PE1

In one of embodiment, a PE (" PE1 ") can be for example such PE, that is, and and Mw < 1.0 × 10 ⁶, as approximately 1.0 × 10 ⁵～approximately 0.90 × 10 ⁶scope in; MWD≤50.0, as in approximately 2.0～approximately 20.0 scope; And the amount < 0.20 every 1.0 × 10 of terminal unsaturation degree ⁴individual carbon atom.Optionally, the Mw of PE1 is approximately 4.0 × 10 ⁵～approximately 6.0 × 10 ⁵scope in, and molecular weight distribution (" MWD ", is defined as M _wdivided by number-average molecular weight) be approximately 3.0～approximately 10.0.The amount optionally≤0.14 every 1.0 × 10 of the terminal unsaturation degree of PE1 ⁴individual carbon atom, or≤0.12 every 1.0 × 10 ⁴individual carbon atom, for example, 0.05～0.14 every 1.0 × 10 ⁴in the scope of individual carbon atom (for example, lower than the detectability of measuring).

PE2

In one of embodiment, the 2nd PE (" PE2 ") can be for example such PE, that is, and and Mw < 1.0 × 10 ⁶, as approximately 2.0 × 10 ⁵～approximately 0.9 × 10 ⁶scope in; MWD≤50.0, as in approximately 2～approximately 50 scope; And the amount > 0.20 every 1.0 × 10 of terminal unsaturation degree ⁴individual carbon atom.Optionally, the amount > 0.30 every 1.0 × 10 of the terminal unsaturation degree of PE2 ⁴individual carbon atom, or > 0.50 every 1.0 × 10 ⁴individual carbon atom, for example, 0.6～10.0 every 1.0 × 10 ⁴in the scope of individual carbon atom.A limiting examples of PE2 is such PE, that is, Mw is approximately 3.0 × 10 ⁵～approximately 8.0 × 10 ⁵scope in, for example approximately 7.5 × 10 ⁵, and MWD is approximately 4～approximately 15.

PE1 and/or PE2 can be for example, Alathon or ethylene/alpha-olefin copolymer, and described ethylene/alpha-olefin copolymer contains 100mol.% based on this multipolymer and is≤comonomer of the one or more of alpha-olefins of 5.0mol.% etc.Described alpha-olefin is optionally one or more of in propylene, 1-butylene, 1-amylene, 1-hexene, 4-methyl-1-pentene, 1-octene, vinyl-acetic ester, methyl methacrylate or vinylbenzene.Such PE can have >=fusing point of 132 DEG C.PE1 can produce according to the method for for example applying Ziegler-Natta catalyst or single site polymerization catalyst, but not necessarily.The amount of terminal unsaturation degree for example can be measured according to the method for describing in the open WO 97/23554 of PCT.PE2 can application examples produces as the catalyzer containing chromium.

PE3

In one of embodiment, the 3rd PE (" PE3 ") can be for example such PE, that is, and and its Mw>=1.0 × 10 ⁶, as approximately 1.0 × 10 ⁶～approximately 5.0 × 10 ⁶scope in; And MWD is in approximately 1.2～approximately 50.0 scope.A limiting examples of PE3 is such PE, that is, Mw is approximately 1.0 × 10 ⁶～approximately 3.0 × 10 ⁶scope in, for example approximately 2.0 × 10 ⁶, and MWD≤20.0, be for example approximately 2.0～approximately 20.0, preferred approximately 4.0～approximately 15.0.PE3 can be for example Alathon or ethylene/alpha-olefin copolymer, described ethylene/alpha-olefin copolymer contains 100mol.% based on this multipolymer and is≤and the comonomer of the one or more of alpha-olefins of 5.0mol.% etc.Described comonomer can be for example propylene, 1-butylene, 1-amylene, 1-hexene, 4-methyl-1-pentene, 1-octene, vinyl-acetic ester, methyl methacrylate or cinnamic one or more of.Such polymkeric substance or multipolymer for example can apply Ziegler-Natta catalyst or single-site catalysts is produced, but not necessarily.Such PE can have >=fusing point of 134 DEG C.The fusing point of PE1～PE3 for example can be applied the method for describing in PCT patent publication No. WO 2008/140835 and measure.

In one or more embodiment, PE comprises B ₁pE1 and/or PE2 and the B of amount ₂the PE3 of amount.In one of embodiment, B ₁in the scope of 60.0 % by weight～96.0 % by weight, and B ₂in the scope of 0.0 % by weight～20.0 % by weight, B ₁and B ₂all weight based on film interpolymer of weight percentage.Based on the weight of total polymer in film, B ₁optionally in the scope of 69.5 % by weight～90.5 % by weight, for example, in the scope of 80.0 % by weight～85.0 % by weight.Based on the weight of total polymer in film, B ₂optionally in the scope of 5.0 % by weight～15.0 % by weight, for example, in the scope of 9.75 % by weight～15.25 % by weight.In one of embodiment, B ₁in the scope of 79.0 % by weight～95.0 % by weight, and B ₂in the scope of 0.0 % by weight～16.0 % by weight.Owing to working as B ₂< is approximately when 7.5 % by weight, may more be difficult to production temperature of fusion>=145 DEG C, the film of for example>=147 DEG C, so in one of embodiment, temperature of fusion>=145 of described film DEG C, for example>=147 DEG C, and B ₂>=8.0 % by weight, for example>=10.0 % by weight.

Polypropylene

In one of embodiment, polypropylene (" PP ") can be for example such polypropylene, that is, and and its Mw>=5.0 × 10 ⁵, as>=6.0 × 10 ⁵, or>=7.5 × 10 ⁵, for example, approximately 0.8 × 10 ⁶～approximately 3.0 × 10 ⁶scope in, as 0.9 × 10 ⁶～2.0 × 10 ⁶scope in.Optionally, Tm >=160.0 DEG C of described PP; And Δ Hm >=80.0J/g, as >=90.0J/g or >=100.0J/g, for example, in the scope of 110J/g～120J/g.Optionally, MWD≤20.0 of described PP, for example, in approximately 1.5～approximately 10.0 scope, as in approximately 2.0～approximately 8.5 scope.Described PP be optionally propylene and≤(random or block) multipolymer of the comonomer of 5.0mol.%, described comonomer is for example the one or more of of following monomer,, alpha-olefin is as ethene, 1-butylene, 1-amylene, 1-hexene, 4-methyl-1-pentene, 1-octene, vinyl-acetic ester, methyl methacrylate or vinylbenzene etc., or diolefine is as divinyl, 1,5-hexadiene, 1,7-octadiene, 1,9-decadiene etc.

In one of embodiment, described PP is isotactic polypropylene.In one of embodiment, this PP has the mmmm five-tuple of (a)>=about 90.0mol%, the mmmm five-tuple of optionally>=about 96.0mol%, and the isotaxy five-tuple of the mmmm five-tuple of preferably>=about 96.0mol% divides rate; And amount≤approximately 50.0 every 1.0 × 10 of (b) founding structure defect ⁴individual carbon atom, for example≤approximately 20 every 1.0 × 10 ⁴individual carbon atom or≤approximately 10.0 every 1.0 × 10 ⁴individual carbon atom, as≤approximately 5.0 every 1.0 × 10 ⁴individual carbon atom.PP optionally has one or more of following properties: (i) Tm>=162.0 DEG C; (ii) the temperature of 230 DEG C and 25 seconds ^-1strain rate under extensional viscosity>=approximately 5.0 × 10 ⁴pa second; (iii) the temperature of approximately 230 DEG C and 25 seconds ^-1strain rate under Trouton ratio>=approximately 15 measured; (iv) melt flow rate (MFR) (" MFR "; ASTM D-1238-95 condition L, under 230 DEG C and 2.16kg)≤about 0.1dg/ minute, for example≤about 0.01dg/ minute (, numerical value be low to moderate MFR do not measure in fact); Or (v) weight of the amount of extractable matter (can extract by PP contacted with the dimethylbenzene boiling) based on PP is≤0.5 % by weight, for example≤0.2 % by weight, as≤0.1 % by weight.

In one of embodiment, described PP is isotaxy PP, and its Mw is approximately 0.90 × 10 ⁶～approximately 2.0 × 10 ⁶scope in; MWD≤8.5, for example approximately 2.0～approximately 8.5, as 2.5～6.0 scope in; And Δ Hm>=90.0J/g.Conventionally, the isotaxy five-tuple point rate of this PP is>=the mmmm five-tuple of 94.0mol%, amount≤approximately 5.0 every 1.0 × 10 of vertical structure defect ⁴individual carbon atom, and Tm>=162.0 DEG C.In one of embodiment, Mw>=6.0 × 10 of contain>=90.0 % by weight of described PP ⁵, MWD≤8.5 and Δ Hm>=90.0J/g isotactic polyprophlene, the weight of described weight percentage based on PP.

A limiting examples of PP, and Tm, the isotaxy five-tuple of measuring PP divide the method for the amount of rate, tacticity, limiting viscosity, Trouton ratio, vertical structure defect and extractable matter, be described in PCT patent publication No. WO 2008/140835, using its content as introducing in this specification sheets with reference to whole.

The Δ Hm of PP measures according to disclosed method in PCT patent publication No. WO 2007/132942, using its content as introducing in this specification sheets with reference to whole.Means of differential scanning calorimetry (DSC) data that Tm can obtain from the Pyris 1 type DSC of application Perkin Elmer Instrument company system are determined.Weigh approximately 5.5～6.5mg sample and be encapsulated into aluminium sample disc.Record like this DSC data, that is, first sample is heated to 230 DEG C with the speed of 10 DEG C/min, be called fusing (not record data) for the first time.Before the cooling-heating cycle of enforcement, sample is kept 10 minutes at 230 DEG C.Then with the speed of 10 DEG C/min, sample is cooled to approximately 25 DEG C from approximately 230 DEG C, is called " crystallization ", then at 25 DEG C, keep 10 minutes, then with the speed of 10 DEG C/min, sample is heated to 230 DEG C, be called " fusing for the second time ".Heat deflection when recording crystallization and melting for the second time.Temperature of fusion (T _m) be the peak temperature of melting curve for the second time, and crystallized temperature (T _c) be the peak temperature of peak crystallization.

Other material

In described film, optionally there is the inorganics (material of for example siliceous and/or aluminium atom, as silicon-dioxide and/or aluminum oxide), and/or thermally stable polymer, the polymkeric substance of for example, describing in the open WO 2007/132942 of PCT and WO 2008/016174 (using the content of two sections of documents as introducing in this specification sheets with reference to whole).In one of embodiment, the above-mentioned materials that described film contains weight≤1.0 % by weight based on this film.

In described film, also can have a small amount of thinner or other material as processing aid, the weight being generally based on this film is the amount of < 1.0 % by weight.

When by described in extrusion when microporous membrane, finished product microporous membrane contains the polymkeric substance for producing extrudate conventionally.Also may have a small amount of thinner or other material that during processing, import, the weight being generally based on film is the amount existence of < 1.0 % by weight.A small amount of polymericular weight may occur in treating processes and reduce, but this is acceptable.In a kind of mode, reduce even if there is molecular weight during processing, cause that the MWD value of polymkeric substance in film and for example, difference for the production of the MWD value (before extruding) of the polymkeric substance of film are only for example approximately 10%, or be only approximately 1%, or be only approximately 0.1%.

Mw and MWD measure

The Mw of polymkeric substance and MWD can use differential refractive index detector (DRI) is housed high temperature size exclusion chromatography instrument " SEC " (GPC PL 220, Polymer Laboratories company system) measure.Measure according to disclosed method in " Macromolecules, Vol.34, No.19, pp.6812-6820 (2001) ".Mensuration by three PLgel Mixed-B posts (can derive from Polymer Laboratories company) for Mw and MWD.For PE, nominal flow rate is 0.5cm ³/ minute, nominal volumetric injection is 300 μ L; Transfer limes, post and DRI detector are all placed in to the baking oven that remains on 145 DEG C.For PP, nominal flow rate is 1.0cm ³/ minute, nominal volumetric injection is 300 μ L; Transfer limes, post and DRI detector are all placed in to the baking oven that remains on 160 DEG C.

1,2 of the Aldrich company SILVER REAGENT processed that the GPC solvent using filters containing the 1000ppm Yoshinox BHT (BHT) of having an appointment, process, 4-trichlorobenzene (TCB).Importing before SEC, carry out degassed to TCB with online de-gassing vessel.Identical solvent is as SEC eluent.Polymers soln is prepared as follows: dry polymer is put into Glass Containers, adds the above-mentioned TCB solvent of requirement, then 160 DEG C and constantly stir under mixture is heated approximately 2 hours.The concentration of polymers soln is 0.25～0.75mg/ml.Before injecting GPC, use model SP260 sample preparation workstation (Sample Prep Station) (can derive from Polymer Laboratories company), with 2 μ m strainers, sample solution is carried out to off-line filtration.

Use 17 kinds of independent Mp (" Mp " is defined as the peak at Mw place) approximately 580～approximately 10,000, the polystyrene standard sample of 000 scope is made calibration curve, proofreaies and correct the separation efficiency of column combination (column set) with this calibration curve.Polystyrene standard sample obtains from Polymer Laboratories company (Amherst, MA).Record the retention volume at the DRI fignal center place of each PS standard, make this data fitting quadratic polynomial (2nd-order polynomial), draw thus calibration curve (logMp is with respect to retention volume).Use can derive from the IGOR Pro analytic sample of Wave Metrics company.

Film

To further describe the present invention according to following embodiment.This description does not also mean that and gets rid of more other embodiment in wide region of the present invention.

In one of embodiment, the present invention relates to such film,, the PE1 that it contains 79.0 % by weight～86.0 % by weight, the PE3 of 9.0 % by weight～16.0 % by weight, and the PP of 4.0 % by weight～6.0 % by weight, wherein, (i) Mw of described PE1 approximately 4.0 × 10 ⁵～approximately 6.0 × 10 ⁵scope in, MWD in approximately 3.0～approximately 10.0 scope, amount≤0.14 of terminal unsaturation degree every 1.0 × 10 ⁴individual carbon atom, and fusing point>=132.0 DEG C; (ii) Mw of described PE3 is approximately 1.0 × 10 ⁶～approximately 3.0 × 10 ⁶scope in, MWD is in approximately 4.0～approximately 15.0 scope, and fusing point>=134.0 DEG C; (iii) described PP is isotactic PP, and its Mw is approximately 0.9 × 10 ⁶～approximately 2.0 × 10 ⁶scope in, MWD≤8.5, for example in 2.0～8.5 scope, as in 2.5～6.0 scope, and Δ Hm>=90.0J/g, for example>=100.0J/g (weight percentage is the weight based on film all); (iv) described film is microporous membrane; And (v) thickness≤12.0 μ m of this film, for example≤8.0 μ m.Described film is optionally unitary film.The weight that this film optionally contains based on film is the PE2 of≤1.0 % by weight.The temperature of fusion of this film is for example>=145.0 DEG C, as>=148.0 DEG C, as>=150.0 DEG C; Stdn electrolysis matter avidity is≤0.24 second/μ m, for example≤0.20 second/μ m, as≤0.18 second/μ m; And it is>=2.85 × 10 that stdn pin is exposed intensity ²mN/ μ m, as>=2.90 × 10 ²mN/ μ m.In one of embodiment, the thickness≤9.0 μ m of described film, it is>=2.85 × 10 that stdn pin is exposed intensity ²mN/ μ m, NEA is≤0.18 second/μ m, and porosity is>=35.0%.The weight of the gross weight of PE1, PE2 and PP based on film is >=95.0 % by weight, for example >=98.0 % by weight, as >=99.0 % by weight.

In another embodiment, the present invention relates to such film,, the PE2 that it contains 79.0 % by weight～86.0 % by weight, the PE3 of 9.0 % by weight～16.0 % by weight, and the PP of 4.0 % by weight～6.0 % by weight, wherein, (i) Mw of described PE2 approximately 3.0 × 10 ⁵～approximately 8.0 × 10 ⁵scope in, MWD in approximately 4～approximately 15 scope, amount>=0.20 of terminal unsaturation degree every 1.0 × 10 ⁴individual carbon atom, and fusing point>=132.0 DEG C; (ii) Mw of described PE3 is approximately 1.0 × 10 ⁶～approximately 3.0 × 10 ⁶scope in, MWD is in approximately 4.0～approximately 15.0 scope, and fusing point>=134.0 DEG C; (iii) described PP is isotactic PP, and its Mw is approximately 0.9 × 10 ⁶～approximately 2.0 × 10 ⁶scope in, MWD≤8.5, for example in 2.0～8.5 scope, as in 2.5～6.0 scope, and Δ Hm>=90.0J/g, for example>=100.0J/g; (iv) described film is microporous membrane; And (v) thickness≤12.0 μ m of this film, be for example 8.0 μ m.The weight of weight percentage based on film.The weight that described film optionally contains based on film is the PE1 of≤1.0 % by weight.For example>=145.0 DEG C of the temperature of fusion of this film, as>=150.0 DEG C; Stdn electrolysis matter avidity is≤0.16 second/μ m, for example≤0.14 second/μ m; And it is < 2.90 × 10 that stdn pin is exposed intensity ²mN/ μ m.Described film is optionally unitary film.The weight of the gross weight of PE1, PE2 and PP based on film is optionally >=95.0 % by weight, for example >=98.0 % by weight, as >=99.0 % by weight.

Although be not limited to this, the present invention includes film application in lithium ion polymer battery, particularly secondary lithium-ion polymer battery as battery diaphragm of aforementioned any embodiment.Although do not want by any theory or model constrained, it is generally acknowledged keeping the basic timing of relative quantity of PP and PE3 in film to replace PE1 with PE2, can cause film increase for the avidity of polymer dielectric and film strength is declined.

Below will the method for producing described microporous membrane be described in more detail.Although according to having described the present invention by extrusion unitary film, the invention is not restricted to this, and description herein do not mean that and get rid of other embodiment that belongs to more wide region of the present invention.

Film production method

In one or more embodiment, described microporous membrane can for example, form mixture by the first polymkeric substance (being PE) and the second polymkeric substance (being PP) and thinner and optional component (mineral filler) are mixed to (for example, by being dry mixed or melt-mixing), then this mixture is extruded and formed extrudate.From this extrudate, remove at least a portion of thinner and form microporous membrane.For example, the mixing diluents such as admixture and whiteruss of PE1 and/or PE2 and PE3 and PP can be formed to mixture, then this mixture be extruded and is processed into the unitary film of thickness≤12.0 μ m.Can apply other layer to extrudate as required, for example, give low the closing of telolemma (shutdown) function.In other words, can be by individual layer extrudate or individual layer microporous membrane lamination or coextrusion and form multilayer film.

In one or more embodiment, the method for producing described film comprises, before removing thinner, along at least one direction described extrudate that stretches.In these or other embodiment, described method comprises, after removing thinner along at least one direction described film that stretches.The method of producing this film optionally also comprises the steps, for example, random time after removing thinner is removed at least a portion of residual any volatile matter from film, is removing before thinner or afterwards, is making film experience thermal treatment (for example thermal-setting or annealing).Can optionally carry out as required the steps such as solvent treatment step, thermal-setting step, the cross-linking step of utilizing ionizing rays and wetting ability treatment step, for example, described in the open WO 2008/016174 of PCT.The quantity of described optionally step and order are not particularly importants.

The production of polymkeric substance-diluent mixture

In one or more embodiment, import the first and second polymkeric substance (as previously mentioned, for example, as PE1 (and/or PE2) and the PE3 of the first polymkeric substance, PP is as the second polymkeric substance) form polymkeric substance-diluent mixture with one or more of mixing diluents.For example, can after the first and second polymkeric substance blendings, form polymkeric substance admixture, then this admixture and thinner (it can be the mixture of thinner, for example solvent mixture) are mixed and generation polymkeric substance-diluent mixture.For example, can in the forcing machines such as extruder, mix.These forcing machines include but not limited to, twin screw extruder, ring-type forcing machine and planetary forcing machine.Enforcement of the present invention is not limited to the forcing machine type of application.In polymkeric substance-diluent mixture, can contain selectively material, for example filler, antioxidant, stablizer and/or thermally stable polymer.That optionally the classification of material and amount can be with described in PCT open WO 2007/132942, WO 2008/016174 and WO 2008/140835 is identical for these, using the content of all these documents as with reference to all introducing in these specification sheetss.

Described thinner is conventionally compatible with the polymkeric substance that is used for producing described extrudate.For example, described thinner can be under extrusion temperature can with described mixed with resin after form single-phase arbitrary substance or its combination.The example of thinner comprises the one or more of of following material: aliphatic hydrocarbon or cyclic hydrocarbon, and for example nonane, decane, naphthalane and paraffin oil, and phthalic ester is as dibutyl phthalate and dioctyl phthalate (DOP).For example can use the paraffin oil that at 40 DEG C, kinematic viscosity is 20～200cSt.Thinner can with in U.S. Patent Publication No. 2008/0057388 and 2008/0057389, describe identical, using it all in this specification sheets of reference introducing.

In one of embodiment, the polymkeric substance admixture in polymkeric substance-diluent mixture contains A ₁the first polymkeric substance (for example PE1 and PE3) and the A of amount ₂second polymkeric substance (for example PP) of amount.In one of embodiment, A ₁>=1.0 % by weight, for example, in the scope of 80.0 % by weight～96.0 % by weight, and A ₂in the scope of 4.0 % by weight～20.0 % by weight, A ₁and A ₂all polymer weight based in mixture of weight percentage.A ₁amount is optionally in the scope of 84.5 % by weight～95.5 % by weight, for example, in the scope of 94.75 % by weight～95.25 % by weight.Based on the total polymer weight in mixture, A ₂amount is optionally in the scope of 4.5 % by weight～15.5 % by weight, for example, in the scope of 4.75 % by weight～5.25 % by weight.It is the polymkeric substance of≤45.0 % by weight that polymkeric substance-diluent mixture optionally contains based on mixture weight, and for example, the total polymer weight based in mixture is in the scope of 30.0 % by weight～40.0 % by weight.The surplus of mixture can be thinner.

In one or more embodiment, the A in described polymkeric substance-diluent mixture ₁the PE of amount can contain B ₁pE1 and/or PE2 and the B of amount ₂the PE3 of amount.In one of embodiment, B ₁in the scope of 60.0 % by weight～96.0 % by weight, and B ₂in the scope of 0.0 % by weight～20.0 % by weight, B ₁and B ₂all polymer weight based in mixture of weight percentage.Based on the weight of whole polymkeric substance in mixture, B ₁optionally in the scope of 69.5 % by weight～90.5 % by weight, for example, in the scope of 80.0 % by weight～85.0 % by weight.Based on the weight of whole polymkeric substance in mixture, B ₂optionally in the scope of 5.0 % by weight～15.0 % by weight, for example, in the scope of 9.75 % by weight～15.25 % by weight.

In one of embodiment, described polymkeric substance-diluent mixture is exposed to for example, temperature within the scope of 140 DEG C～250 DEG C, 210 DEG C～230 DEG C in the time extruding.

Produce extrudate

In one of embodiment, described polymkeric substance-diluent mixture is derived and produced extrudate from forcing machine by mould.This extrudate should have suitable thickness, thereby produces and after procedure of processing, have expection thickness (conventionally≤12.0 μ telolemma m).For example, the thickness of extrudate can be in the scope of approximately 1.0 μ m～approximately 10.0 μ m or approximately 3.0 μ m～approximately 8.0 μ m.In one or more embodiment, the final thickness of telolemma (after processing) is≤12.0 μ m, as≤10.0 μ m.

Conventionally extrude with the polymkeric substance-diluent mixture under molten state.In the time using sheet forming mould, conventionally die lip is heated to high temperature, for example, in the scope of 180 DEG C～240 DEG C.The suitable operational condition that enforcement is extruded is disclosed in the open WO 2007/132942 of PCT and WO 2008/016174.

Extrudate can be exposed at the temperature within the scope of approximately 10 DEG C～approximately 45 DEG C and form cooling extruded thing as required.Speed of cooling is not particularly important.For example, can be under the speed of cooling at least about 30 DEG C/min cooling extruded thing, until the gelling temperature basic identical (or lower) of the temperature of extrudate (cooling temperature) and extrudate.Cooling operational condition for example can be identical with disclosed condition in PCT publication number WO 2007/132942, WO 2008/016174 and WO2008/140835.

The stretching (upstream stretching) of extrudate

Can such as, at the upper stretching extrudate of at least one direction (at least one in-plane such as MD or TD etc.) or cooling extruded thing (being called " upstream stretching " or " wet stretching ").It is generally acknowledged, such stretching causes polymkeric substance in extrudate orientation at least to a certain degree.This orientation is called " upstream " orientation.Can combine the extrudate that stretches, the method for for example describing in PCT publication number WO 2008/016174 by tenter machine method for example, roll process, inflation method or its.Can carry out single shaft or biaxial stretch-formed, in some embodiments, extrudate be carried out biaxial stretch-formed.Biaxial stretch-formed in the situation that, can apply simultaneously biaxial stretch-formed, successively stretch or multistage stretching (for example biaxial stretch-formed and successively combination of stretching simultaneously) in any; In some embodiments, extrudate is carried out to the while biaxial stretch-formed.In the time that use is biaxial stretch-formed, do not need identical at the elongation multiple of each draw direction.

In the time of uniaxial extension, tensile elongation multiple for example can be >=2 times, as 3～30 times.When biaxial stretch-formed, the tensile elongation multiple in either direction for example can be >=3 times, that is, enlarged areas multiple is >=9 times, for example >=16 times, as >=25 times.The example of above-mentioned stretching step comprises, stretches with the enlarged areas multiple of approximately 9 times～approximately 49 times.In addition, needn't be identical in the amount of tension of all directions.Extend multiple and make the multiplication of film size.For example, original width (TD) will have the final width of 8.0cm be stretched to the elongation multiple of 4 times along TD after for the film of 2.0cm.

Can on one side extrudate be exposed at the temperature (upstream draft temperature) within the scope of about Tcd temperature～Tm, stretch on one side, wherein, Tcd and Tm are defined as crystal disperse temperature (crystal dispersion temperature) and the fusing point for the production of the PE (being generally as the PE of PE1 or PE3) that in the polyethylene of extrudate, fusing point is minimum.Measure the temperature profile of dynamic viscoelastic according to ASTM D 4065, determine thus crystal disperse temperature.In embodiment at Tcd within the scope of approximately 90 DEG C～approximately 100 DEG C, draft temperature can be 90.0 DEG C～122.0 DEG C, for example 108.0 DEG C～116.0 DEG C, as 110.0 DEG C～114.0 DEG C.

Carry out near that when sample (as extrudate, dry extrudate, film etc.) is exposed at high temperature, this exposure can be by adding warm air, be then transported to warm air sample.The temperature of warm air is controlled in and temperature required identical set(ting)value conventionally, then for example by plenum system, warm air is sent to sample.Also can apply sample is exposed to other method at high temperature, use with the method that adds warm air simultaneously or replace and add warm air and use, described other method comprises ordinary method, for example, sample is exposed to the surface of heating, carries out infrared heating etc. in baking oven.

Removing of thinner

In one of embodiment, from the extrudate stretching, remove at least a portion of (or displacement) thinner and form desciccator diaphragm.Disclosed in PCT publication number WO 2008/016174, can use displacement (or " washing ") solvent to remove (wash away or replace) thinner.

In one of embodiment, can remove after thinner, from desciccator diaphragm, remove at least a portion of residual any volatile matter (as cleaning solvent).Can use any means that can remove cleaning solvent, comprise ordinary method, such as heat drying, air-dry (fluidizing air) etc.For example can be identical with PCT publication number WO 2008/016174 disclosed condition for the operational condition of removing the volatile matter such as cleaning solvent.

The selectivity stretching (downstream stretching) of film

Can for example, along at least one direction (MD and/or TD) direction stretching desciccator diaphragm (being called " downstream stretching " or " dry stretching ", because at least a portion of thinner has been removed or has replaced).It is generally acknowledged that this stretching causes film interpolymer orientation at least to a certain degree.This orientation is called as " downstream orientation ".Before downstream stretches, desciccator diaphragm has original dimensions (the first dry length) along MD and the original dimensions (the first dry width) along TD.The term " the first dry width " using as this specification sheets refers to the size of the dry desciccator diaphragm stretching before starting along TD.Term " the first dry length " refers to the size of the dry desciccator diaphragm stretching before starting along MD.For example, can use that tenter machine stretching device of describing in WO 2008/016174.

Can be by desciccator diaphragm along MD with in approximately 1.0～approximately 1.6 scopes, the elongation multiple (" MD does tensile elongation multiple ") in 1.1～1.5 scopes is stretched to the second dry length that is greater than the first dry length from the first dry length according to appointment.Use when TD is dry to stretch, desciccator diaphragm can be stretched to the second dry width that is greater than the first dry width along TD with certain elongation multiple (" TD does tensile elongation multiple ") from the first dry width.The dry tensile elongation multiple of TD is optionally not less than the dry tensile elongation multiple of MD.The dry tensile elongation multiple of TD can be in approximately 1.1～approximately 1.6, according to appointment 1.1～1.5 scope.For dry stretching, can along MD and TD carries out successively or stretch simultaneously.Use when twin shaft is dry to stretch, dry stretching can or successively be carried out along MD and TD direction simultaneously.In the time successively doing stretching, conventionally first carry out MD stretching, then carry out TD stretching.

In some embodiments, particularly consider the thickness of some certain films produced according to the invention, in the time implementing embodiments of the present invention, avoid dry and stretch or minimize it.For example, produce in the procedure of processing of film with desired thickness without any dry stretching step.In other embodiments, procedure of processing comprises elongation multiple≤1.1, in other embodiments≤1.08, in other embodiments≤1.05, in other embodiments≤1.03 dry stretching.

Dry stretching can, at the temperature of desciccator diaphragm is exposed to≤Tm (downstream draft temperature), for example, be carried out in the scope of about Tcd-20.0 DEG C～Tm time.In one of embodiment, make film be exposed to approximately 70.0 DEG C～approximately 135.0 DEG C, at for example, temperature within the scope of approximately 110.0 DEG C～approximately 132.0 DEG C, 120.0 DEG C according to appointment～approximately 130.0 DEG C, stretch.

In one of embodiment, the dry tensile elongation multiple of MD is about 1.0; The dry tensile elongation of TD multiple≤1.6, for example, in approximately 1.05～approximately 1.5, according to appointment 1.1～1.5 scope; And film is exposed at the temperature within the scope of approximately 120.0 DEG C～approximately 130.0 DEG C, does stretching.

Dry rate of extension is not particularly important.In one of embodiment, dry rate of extension is >=1%/second along draw direction (MD or TD), and stretches for MD and TD, and speed can independently be selected.Rate of extension is optionally >=2%/second, for example >=3%/second, as >=10%/second.In one of embodiment, rate of extension is in the scope of 2%/second～25%/second.Although rate of extension is not particularly important, the upper limit can be that 50%/second is in case film rupture.

The controlled of film width dwindles

After dry stretching, optionally desciccator diaphragm is implemented to the in check of width and dwindle, that is, be contracted to the 3rd dry width from the second dry width, the 3rd dry width is compared the first dry width in the scope of 0.9 times～approximately 1.5 times.Optionally, the second dry width is compared the first dry width in the scope of 1.25～1.35 times, and the 3rd dry width is compared the first dry width in the scope of 0.95～1.05 times.Reduced width conventionally at film is exposed to >=Tcd-30.0 DEG C but≤carry out at the temperature of Tm.For example, in reduced width, film can be exposed at the temperature within the scope of approximately 70.0 DEG C～approximately 135.0 DEG C to for example approximately 110.0 DEG C～approximately 132.0 DEG C, 120.0 DEG C according to appointment～approximately 130.0 DEG C.

Although the temperature during controlled the dwindling of width can be identical with described downstream draft temperature, but not necessarily, in one of embodiment, during controlled the dwindling of width, the residing temperature of film is compared downstream draft temperature and is >=1.01 times, for example, in the scope of 1.05 times～1.1 times.In certain mode, at the on one side film is exposed to≤temperature of 130.0 DEG C, carry out dwindling of film width on one side, the 3rd dry width is compared the first dry width in the scope of 0.95～1.05 times.

Thermal-setting

For example, after described dry stretching, after controlled the dwindling of width or after both, after removing thinner, optionally film is carried out to thermal treatment at least one times (thermal-setting).It is generally acknowledged by thermal-setting crystalchecked and form even thin layer in film.In certain mode, thermal-setting is being exposed to film at the temperature within the scope of Tcd～Tm and is carrying out, for example, in the scope of approximately 70.0 DEG C～approximately 135.0 DEG C, 110.0 DEG C according to appointment～approximately 132.0 DEG C, 120.0 DEG C according to appointment～approximately 130.0 DEG C.

Although heat-set temperature can be identical with downstream draft temperature, not necessarily.In one of embodiment, when thermal-setting, the residing temperature of film is compared downstream draft temperature and is >=1.01 times, for example, in the scope of 1.05 times～1.1 times.Typically, thermal-setting is carried out the sufficient time so that form uniform thin layer in film, for example≤1,000 second, as the time within the scope of 1～600 second.In one of embodiment, thermal-setting operates under conventional thermal-setting " heat fixation " condition.Term " heat fixation " refers in thermal-setting, the thermal-setting of for example carrying out when using the periphery of tenter machine cloth gripper clamping film to maintain the length of film and width substantially constant.

Can after thermal-setting step, optionally carry out anneal.Annealing is a kind of thermal treatment that film is not applied to loading, and for example, heating chamber or air floatation type (air-floating-type) heating chamber that can have a conveying belt by use carry out.Annealing also can be carried out continuously after thermal-setting under the state of lax tenter machine.When annealing, film can be exposed at the temperature of Tm or lower scope, for example, in the scope of approximately 60 DEG C～about Tm-5 DEG C.It is generally acknowledged that Gas permeability and the intensity of microporous membrane improve by annealing.

Optionally carry out as required hot-rolling processing, hot solvent processing, crosslinking Treatment, wetting ability processing and coating and process, for example, press described in PCT publication number WO 2008/016174.

The characteristic of film

In one or more embodiment, described film is the permeable microporous membrane of liquid under normal pressure (water-based and non-water).Therefore, this film can be used as battery diaphragm, filtering membrane etc.This film is particularly useful as the such as BSF of nickel-hydrogen cell, nickel-cadmium cell, nickel-zinc cell, silver-zinc battery, lithium ion battery, lithium ion polymer battery etc. of secondary cell.In one of embodiment, the present invention relates to comprise the lithium-ion secondary cell of the BSF that contains described film.Such battery is described in PCT publication number WO 2008/016174, the document is incorporated to this specification sheets in full for referencial use.

In one or more embodiment, described microporous membrane is unitary film, and it is suitable for as BSF for polymer batteries such as lithium ion polymer batteries." polymer dielectric " using in this specification sheets uses its common implication, refers to the ionogen in polymer battery.As skilled in the art to understand, polymer battery contains ionogen, for example lithium ion, and it is scattered in, is suspended in or is dissolved in polymeric media.Therefore, ionogen affinity or Gas permeability represent that the ionogen such as polymeric media and/or lithium ion sees through the ability of film.

Described film can have one or more of following properties.

Thickness

In one of embodiment, the thickness of telolemma is≤12.0 μ m, for example≤10.0 μ m, as in the scope of approximately 1.0 μ m～approximately 10.0 μ m.For example, unitary film can have the thickness within the scope of the μ m of approximately 4.5 μ m～approximately 9.5.The thickness of film for example can use contact thickness gauge (contact thickness meter) to measure on the width of 10cm with the interval of 1cm in the vertical, then obtains mean value and obtains film thickness.It is proper that " RC-1 " type screw micrometer that can derive from Maysun Corp. (Wu Guan island, city of Fuji, county of Shizuoka 746-3,416-0946) maybe can derive from " Litematic " equal thickness meter of Mitsutoyo company.The contactless thickness measuring methods such as optical thickness measuring method are also applicable to.

Porosity

The porosity of film is normally measured like this, that is, and and by the weight of the equal non-porous film of the actual weight of film and 100% polymkeric substance (have in the meaning of identical polymkeric substance composition, length, width and thickness on an equal basis) is compared.Then, use following formula to obtain porosity: porosity (being expressed as a percentage)=99% × (w1/w2), wherein " w1 " is the actual weight of film, and " w2 " is the weight with (same polymer) equal non-porous film of same size and thickness.In one of embodiment, porosity >=20.0% of film, for example >=31.0%, as >=35.0%.For example, the porosity of film can be 20.0%～80.0%, as 36.0%～40.0% scope in.

Stdn Gas permeability

In one of embodiment, stdn Gas permeability≤50.0 of described film second/100cm ³/ μ m, for example, at approximately 10.0 seconds/100cm ³/ μ m～approximately 45.0 second/100cm ³/ μ m, 15.0 seconds/100cm according to appointment ³/ μ m～approximately 40.0 second/100cm ³in the scope of/μ m.Because Gas permeability value is standardized as the value of the equal film of 1.0 μ m film thicknesses, so the Gas permeability value of film is with " second/100cm ³/ μ m " unit representation.According to JIS P8117 bioassay standard Gas permeability, use formula A=1.0 μ m* (X)/T ₁result standard is turned to the Gas permeability value of the equal film that 1.0 μ m are thick, wherein, X is that actual (real) thickness is T ₁the Gas permeability observed value of film, A is the stdn Gas permeability of the equal film that 1.0 μ m are thick.

Stdn pin is exposed intensity

The pin that the pin of film is exposed the equal film of intensity taking the thick and porosity of 1.0 μ m as 30% is exposed intensity and is represented, its unit is [mN/ μ m].Pin is exposed intensity and is defined as: the pin that is 1mm with the diameter of spherical end surface (radius of curvature R: 0.5mm), and taking the speed puncture thickness of 2mm/ second as T ₁film time the maximum loading at room temperature measured.Use formula S ₂=[30%*1.0 μ m* (S ₁)]/[T ₁* (100%-P)] pin is exposed to intensity (" S ") be standardized as 1.0 μ m pin thick and the equal film that porosity is 30% and expose intensity level, in formula, S ₁" measured value " that pin is exposed intensity, S ₂be that stdn pin is exposed intensity, P is the porosity measurement value of film, and T ₁it is the mean thickness of film.In one of embodiment, the stdn pin of film is exposed intensity>=2.50 × 10 ²mN/ μ m, for example>=2.90 × 10 ²mN/ μ m.The stdn pin of film is exposed intensity optionally>=3.0 × 10 ²mN/ μ m, for example, 3.05 × 10 ²mN/ μ m～4.5 × 10 ²in the scope of mN/ μ m.

Closing temperature (shutdown temperature)

Measure the closing temperature of described microporous membrane by disclosed method in PCT publication number WO 2007/052663, the document is incorporated to this specification sheets in full for referencial use.According to the method, in the time measuring the Gas permeability of film, microporous membrane is exposed to start from 25 DEG C increase progressively at temperature (5 DEG C/min).The Gas permeability (Gurley value) that " closing temperature " of microporous membrane is defined as to microporous membrane exceedes 1.0 × 10 at first ⁵second/100cm ³time temperature.Use Gas permeability meter (can derive from the EGO-1T of Asahi Seiko Kabushiki Kaisha) to measure the Gas permeability of microporous membrane according to JIS P 8117.In one of embodiment, the closing temperature of film is≤136 DEG C, for example, in the scope of 132.5 DEG C～134.5 DEG C.

Temperature of fusion

The application method identical with measuring closing temperature measured the closing temperature of described microporous membrane.According to the method, in the time measuring the Gas permeability of film, microporous membrane is exposed to start from 25 DEG C increase progressively temperature (5 DEG C/min), to exceeding at the temperature of closing temperature of film.Continuation is by this film heating, and the Gas permeability (Gurley value) that " temperature of fusion " of microporous membrane is defined as to microporous membrane drops to 1.0 × 10 at first ⁵second/100cm ³time temperature.Use Gas permeability meter (can derive from the EGO-1T of Asahi Seiko Kabushiki Kaisha) to measure the Gas permeability of microporous membrane according to JIS P 8117.In one of embodiment, the temperature of fusion of film of the present invention is >=145.0 DEG C, for example >=150.0 DEG C, as >=160.0 DEG C.In one of embodiment, the temperature of fusion of described microporous membrane 146.0 DEG C～170.0 DEG C, as the scope of 150.0 DEG C～165 DEG C in.

Percent thermal shrinkage at 105 DEG C

In one of embodiment, described film at 105 DEG C along the percent thermal shrinkage of at least one in-plane (for example MD or TD) be for example≤10.0%, >=6.0%, for example, in 1.0%～5.0% scope.This film is as follows along the shrinkage determination of MD and TD at 105.0 DEG C: (i) at room temperature along the specimen size of MD and TD two directional survey microporous membranes, (ii) within 8 hours, make its equilibration not applying at the temperature that under loading, microporous membrane sample is placed in to 105 DEG C, then (iii) is along the size of MD and TD two these films of directional survey.Heat (or " thermic ") shrinking percentage along MD and TD direction can record like this: use the measurement result of (i) divided by the measurement result of (ii), and represent the business of gained with percentage.

Tensile strength

In one of embodiment, described film is along the tensile strength of MD and TD separately all>=1.4 × 10 ⁵kPa, for example, 1.5 × 10 ⁵kPa～2.0 × 10 ⁵in the scope of kPa.According to ASTM D-882A, measure tensile strength along MD and TD.

Stdn electrolysis matter avidity

(thickness is≤12.0 μ membrane samples m) to preparation 50mm × 50mm, lies in than this film and has on more large-area glass substrate.Using visible light irradiates film from top, and the film while measuring beginning is opaque.Film is exposed to 25 DEG C, at the temperature of ± 3 DEG C, gets 500.0 μ l propylene carbonates (purity is >=99vol%) drop and drop in the surface of film.The ionogen avidity (" EA ") of film is defined as described drop and starts after contact membranes to become the transparent average elapsed time to film.Replication obtains mean value five times.

Stdn electrolysis matter avidity (" NEA ") is defined as EA/ (average film thickness representing with μ m).The unit of NEA is [second/μ m].In one of embodiment, NEA≤5.0 of film second/μ m, for example≤2.5 seconds/μ m, as in the scope of 0.1 second/μ m～0.9 second/μ m.

Embodiment

Describe in more detail the present invention with reference to following embodiment, but this does not limit the scope of the invention.

Embodiment 1

(1) preparation of polymkeric substance-diluent mixture

By the following method thinner is mixed with the polymkeric substance admixture of two kinds of polyethylene (PE1 and PE3) and PP, prepare polymkeric substance-diluent mixture.The Mw that described polymkeric substance admixture contains (a) 90.0 % by weight is 5.6 × 10 ⁵, MWD is 4.0, amount≤0.14 every 1.0 × 10 of terminal unsaturation degree ⁴individual carbon atom and Tm are the PE (PE1) of 136.0 DEG C, and (b) Mw of 5.0 % by weight is 1.9 × 10 ⁶, MWD be 5.1 and Tm be the PE (PE3) of 136.0 DEG C, and (c) Mw of 5.0 % by weight is 5.3 × 10 ⁵, and Δ Hm be about the isotaxy PP (PP2) of 80J/g, the polymer weight of described weight percentage based on mixing.

Then, it is in 58mm and the L/D strong mixed type twin screw extruder that is 42 that 35.0 % by weight of resulting polymers admixture are packed into internal diameter, then by side opening for feed to the whiteruss (being 50cst at 40 DEG C) that injects 65.0 % by weight in twin screw extruder.Under 220 DEG C and 320rpm, mix and prepare polymkeric substance-diluent mixture, the weight of described weight percentage based on polymkeric substance-diluent mixture.

(2) production of film

Described polymkeric substance-diluent mixture is fed to sheet forming mould from forcing machine, forms extrudate (in the form of a sheet) from wherein extruding.Die temperature is about 210 DEG C (or as temperature of specifically listing in table 1).By extrudate by contacting and make it cooling with the cooling roller that is controlled at 20 DEG C.Using tentering drawing machine that cooling extrudate is carried out to biaxial stretch-formed (upstream stretchings) elongation multiple extremely separately along MD and TD both direction at the temperature of approximately 112.5 DEG C (or as table in temperature of specifically listing) is simultaneously 5 times.Then three layers of gel sheet material that stretch are impregnated into be controlled in the methylene dichloride of 25 DEG C bathe in to remove whiteruss, to whiteruss weight based in polymkeric substance-diluent mixture be the amount of≤1.0 % by weight.Make film dry by air-flow at room temperature subsequently.Keep the size substantially constant of film, then by its 128.8 DEG C of (or as table in temperature of providing) lower thermal-settings 10 minutes with the microporous membrane that manufactures a finished product.The characteristic of selected starting raw material, processing conditions and film is listed in table 1.

Embodiment 2

Repeat embodiment 1, difference is as shown in table 1.Parent material and the process operation condition of application are all identical with embodiment 1, and difference as shown in Table.For example, PP1 can be 1.1 × 10 by Mw ⁶and the polypropylene that Δ Hm is 114J/g (PP1) replaces; PE1 can be 7.46 × 10 by Mw ⁵, Tm is amount>=0.20 every 1.0 × 10 of 134.0 DEG C and terminal unsaturation degree ⁴the PE (PE2) of individual carbon atom replaces.The film of embodiment 4 and 5 was exposed to respectively at the temperature of 130.2 DEG C (embodiment 4) and 130.0 DEG C (embodiment 5) on one side before thermal-setting, and experiencing stretching (downstream stretching) to the TD elongation multiple of removing thinner in downstream is on one side 1.4.

[table 1]

Discuss

Embodiment 1～5 illustrates that the PP that can be >=4.0 % by weight from PE and the weight based on film produces the thinner microporous membrane for example, with practical temperature of fusion (>=145.0 DEG C).Such film is suitable for the BSF in the lithium ion polymer battery of making lithium ion battery, for example application of thin BSF.As described in Example 5, in the time that the concentration of PP increases, NEA enlarges markedly.As for the film of the PP that contains > 20.0 % by weight, larger NEA value makes it more be difficult to apply the BSF of described film as polymer battery.In other words, described data show, although the PP of margin amount is essential for reaching practical temperature of fusion, increases PP load NEA is exerted an adverse impact.Comparative example 1 has been illustrated the BSF that does not contain PP.Such film has applicable NEA, exposes intensity but also have lower temperature of fusion, lower porosity and lower stdn pin.

Whole patents including priority documents, that this specification sheets is quoted, experimental working technique and other document, in its disclosed content and the reconcilable scope of the present invention, all introduce this specification sheets for referencial use, in addition, the authority that above-mentioned introducing is allowed to is for introducing completely.

Although described disclosed exemplary form in this specification sheets with special shape, it should be understood that various other versions are apparent to those skilled in the art, and those skilled in the art are not departing from the application's design and scope and can easily implement.Therefore, embodiment and explanation that the scope of the appended claim of this specification sheets is not limited to propose herein, claim is understood to include patentable whole new features whole features, that this specification sheets had of being regarded as equivalent feature by the application those skilled in the art.

This specification sheets is enumerated lower limit and upper the prescribing a time limit of numerical value, is commonly considered as the scope from any lower limit to any upper limit.

Utilizability in industry

Microporous membrane of the present invention is suitable for makes battery diaphragm.

Claims

1. a film, the polyethylene of contain>=1.0 % by weight and Mw>=5.0 × 10 of 4.5 % by weight～15.5 % by weight ⁵, and the polypropylene of △ Hm>=80.0J/g, the weight of described weight percentage based on film interpolymer;

Wherein, the isotactic polyprophlene of contain>=90.0 % by weight of described polypropylene, Mw>=6.0 × 10 of described isotactic polyprophlene ⁵, MWD≤8.5 and △ Hm>=90.0J/g, the isotaxy five-tuple point rate of described isotactic polyprophlene is more than mmmm five-tuple 96.0mol%, described weight percentage is based on polyacrylic weight,

Described film is microporous membrane, and, the thickness of described film is≤10.0 μ m, the have>=temperature of fusion of 145.0 DEG C of described film and the stdn electrolysis matter avidity of≤2.5 seconds/μ m, and the porosity of described film is 20%～80%, stdn Gas permeability is≤50.0 seconds/100cm ³/ μ m, and stdn pin to expose intensity be>=2.5 × 10 ²mN/ μ m.

2. film as claimed in claim 1, wherein, (i) described polyethylene contains Mw < 1.0 × 10 ⁶the first polyethylene and Mw>=1.0 × 10 ⁶the second polyethylene; (II) described first polyethylene is with the B within the scope of 72.0 % by weight～90.0 % by weight ₁amount exists; (III) described second polyethylene is with the B within the scope of 5.0 % by weight～15.0 % by weight ₂amount exists; And described polyacrylic amount is in the scope of 5.0 % by weight～8.0 % by weight; Described weight percentage is the weight based on film interpolymer all.

3. film as claimed in claim 2, wherein, described the first poly Mw is 4.0 × 10 ⁵～6.0 × 10 ⁵scope in, and MWD is in 3.0～10.0 scope; Described the second poly Mw is 1.0 × 10 ⁶～3.0 × 10 ⁶scope in, and MWD is in 4.0～15.0 scope.

4. film as claimed in claim 3, wherein, the amount < 0.20 every 1.0 × 10 of described the first poly terminal unsaturation degree ⁴individual carbon atom.

5. a battery diaphragm, contains the microporous membrane described in any one in claim 1～4.

6. the production method of microporous membrane claimed in claim 1, comprises the steps:

Step (1): the mixture of thinner and polymkeric substance is extruded, and described polymkeric substance contains A ₁polyethylene and the A of amount ₂the polypropylene of amount, wherein, A ₁>=1.0 % by weight, and A ₂in the scope of 4.5 % by weight～15.5 % by weight, weight percentage is the polymer weight based in polymkeric substance-diluent mixture all;

Step (2): described extrudate is stretched at least one in-plane; And

Step (3): at least a portion of removing thinner from stretching extrudate.

7. method as claimed in claim 6, wherein, based on the polymer weight in polymkeric substance-diluent mixture, A ₁in the scope of 84.5 % by weight～95.5 % by weight, and, described poly Mw < 1.0 × 10 ⁶.

8. the method as described in claim 6 or 7, wherein, (i) A ₂in the scope of 4.5 % by weight～15.5 % by weight; It is the isotactic polyprophlene of>=90.0 % by weight that (II) described polypropylene contains based on polyacrylic weight, Mw>=6.0 × 10 of described isotactic polyprophlene ⁵, MWD≤8.5 and △ Hm>=90.0J/g.

9. method as claimed in claim 6, wherein, (i) described polyethylene contains Mw < 1.0 × 10 ⁶the first polyethylene and Mw>=1.0 × 10 ⁶the second polyethylene; (II) described first polyethylene is with the B within the scope of 69.5 % by weight～90.5 % by weight ₁amount exists; (III) described second polyethylene is with the B within the scope of 5.0 % by weight～15.0 % by weight ₂amount exists; Described weight percentage is the gross weight based on polymkeric substance in mixture all.

10. method as claimed in claim 6, is also included in step (2) before by step cooling described extrudate.

11. methods as claimed in claim 6, are also included in step (3) stretches described film afterwards step along at least one direction and make afterwards described film experience heat treated step in step (3).

12. methods as claimed in claim 11, wherein, described draw direction is TD.

13. methods as claimed in claim 6, wherein, the stretching of step (2) is performed such: on one side described extrudate is exposed at the temperature within the scope of 90.0 DEG C～125.0 DEG C, carries out biaxial stretch-formed on one side in area enlargement ratio is the scope of 9 times～49 times.

14. methods as claimed in claim 6, the step that is also included in step (3) removes afterwards residual any volatile matter from film.

15. 1 kinds of membrane products are to make by the method described in any one in claim 6～14.

16. 1 kinds of batteries, comprise positive pole, negative pole, ionogen and the battery diaphragm between described positive pole and negative pole, and this battery diaphragm comprises the film described in any one in claim 1～5.

17. batteries as claimed in claim 16, wherein, the thickness≤10.0 μ m of described film, and described battery is lithium ion polymer battery.

18. 1 kinds of power trucks or hybrid electric vehicle, comprise the power set being electrically connected with the battery described in claim 16 or 17.