JP2014070092A - Microporous film and separator for battery - Google Patents
Microporous film and separator for battery Download PDFInfo
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- JP2014070092A JP2014070092A JP2012214861A JP2012214861A JP2014070092A JP 2014070092 A JP2014070092 A JP 2014070092A JP 2012214861 A JP2012214861 A JP 2012214861A JP 2012214861 A JP2012214861 A JP 2012214861A JP 2014070092 A JP2014070092 A JP 2014070092A
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- QQONPFPTGQHPMA-UHFFFAOYSA-N propylene Natural products CC=C QQONPFPTGQHPMA-UHFFFAOYSA-N 0.000 claims abstract description 41
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 claims abstract description 32
- 229920001577 copolymer Polymers 0.000 claims abstract description 31
- 238000000034 method Methods 0.000 abstract description 46
- 238000001125 extrusion Methods 0.000 abstract description 8
- 238000000465 moulding Methods 0.000 abstract description 7
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 abstract description 2
- 230000002349 favourable effect Effects 0.000 abstract description 2
- 229910052744 lithium Inorganic materials 0.000 abstract description 2
- 239000004744 fabric Substances 0.000 abstract 2
- 239000010408 film Substances 0.000 description 112
- 230000035699 permeability Effects 0.000 description 27
- 238000009998 heat setting Methods 0.000 description 12
- 238000010622 cold drawing Methods 0.000 description 11
- 238000004519 manufacturing process Methods 0.000 description 10
- -1 battery separators Substances 0.000 description 9
- 238000010438 heat treatment Methods 0.000 description 9
- 238000000137 annealing Methods 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 7
- RFFLAFLAYFXFSW-UHFFFAOYSA-N 1,2-dichlorobenzene Chemical compound ClC1=CC=CC=C1Cl RFFLAFLAYFXFSW-UHFFFAOYSA-N 0.000 description 6
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 6
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 6
- 239000005977 Ethylene Substances 0.000 description 6
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 6
- 229910001416 lithium ion Inorganic materials 0.000 description 6
- 239000004711 α-olefin Substances 0.000 description 6
- 238000004804 winding Methods 0.000 description 5
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 4
- 238000001460 carbon-13 nuclear magnetic resonance spectrum Methods 0.000 description 4
- 239000003063 flame retardant Substances 0.000 description 4
- 230000000704 physical effect Effects 0.000 description 4
- 229920001155 polypropylene Polymers 0.000 description 4
- 239000004743 Polypropylene Substances 0.000 description 3
- 238000005227 gel permeation chromatography Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000012071 phase Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 229920005989 resin Polymers 0.000 description 3
- 239000011347 resin Substances 0.000 description 3
- RFFLAFLAYFXFSW-WFVSFCRTSA-N 1,2-dichloro-3-deuteriobenzene Chemical compound [2H]C1=CC=CC(Cl)=C1Cl RFFLAFLAYFXFSW-WFVSFCRTSA-N 0.000 description 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 2
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 2
- 239000004793 Polystyrene Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- ADCOVFLJGNWWNZ-UHFFFAOYSA-N antimony trioxide Chemical compound O=[Sb]O[Sb]=O ADCOVFLJGNWWNZ-UHFFFAOYSA-N 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 230000008602 contraction Effects 0.000 description 2
- 239000013078 crystal Substances 0.000 description 2
- 230000001186 cumulative effect Effects 0.000 description 2
- 238000004090 dissolution Methods 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- 230000010220 ion permeability Effects 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000000155 melt Substances 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- 238000001471 micro-filtration Methods 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 239000000178 monomer Substances 0.000 description 2
- 229920000098 polyolefin Polymers 0.000 description 2
- 229920005606 polypropylene copolymer Polymers 0.000 description 2
- 229920005629 polypropylene homopolymer Polymers 0.000 description 2
- 229920002223 polystyrene Polymers 0.000 description 2
- 239000011342 resin composition Substances 0.000 description 2
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 1
- 239000004114 Ammonium polyphosphate Substances 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 241000692870 Inachis io Species 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 1
- 235000019826 ammonium polyphosphate Nutrition 0.000 description 1
- 229920001276 ammonium polyphosphate Polymers 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910000019 calcium carbonate Inorganic materials 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 230000006835 compression Effects 0.000 description 1
- 238000007906 compression Methods 0.000 description 1
- 238000001816 cooling Methods 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 229930195729 fatty acid Natural products 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 150000002367 halogens Chemical class 0.000 description 1
- 239000012760 heat stabilizer Substances 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 239000011256 inorganic filler Substances 0.000 description 1
- 239000007791 liquid phase Substances 0.000 description 1
- 150000002739 metals Chemical class 0.000 description 1
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 239000002667 nucleating agent Substances 0.000 description 1
- 239000012766 organic filler Substances 0.000 description 1
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920002239 polyacrylonitrile Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 229920006124 polyolefin elastomer Polymers 0.000 description 1
- 229920001296 polysiloxane Polymers 0.000 description 1
- 229920005604 random copolymer Polymers 0.000 description 1
- 239000012779 reinforcing material Substances 0.000 description 1
- 239000012748 slip agent Substances 0.000 description 1
- 235000012424 soybean oil Nutrition 0.000 description 1
- 239000003549 soybean oil Substances 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
Classifications
-
- 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
- Y02E60/13—Energy storage using capacitors
-
- 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
- Y02E60/30—Hydrogen technology
- Y02E60/50—Fuel cells
Landscapes
- Electric Double-Layer Capacitors Or The Like (AREA)
- Cell Separators (AREA)
- Fuel Cell (AREA)
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
Abstract
Description
本発明は、微多孔性フィルム及び電池用セパレータに関する。 The present invention relates to a microporous film and a battery separator.
微多孔性フィルム、特にポリオレフィン系微多孔性フィルムは、精密濾過膜、電池用セパレータ、コンデンサー用セパレータ、燃料電池用材料などに使用されており、特にリチウムイオン電池用セパレータとして使用されている。また近年、リチウムイオン電池は、携帯電話、ノート型パソコンなどの小型電子機器用途として使用されている一方で、電気自動車やハイブリッド自動車などへの応用も図られている。 Microporous films, particularly polyolefin microporous films, are used in microfiltration membranes, battery separators, capacitor separators, fuel cell materials, and the like, and in particular, lithium ion battery separators. In recent years, lithium-ion batteries have been used for small electronic devices such as mobile phones and laptop computers, and are also being applied to electric vehicles and hybrid vehicles.
ここで、電気自動車やハイブリッド自動車用途に用いられるリチウムイオン電池には、短時間に多くのエネルギーを取り出すための、より高い出力特性が要求される。また、このような用途に用いられるリチウムイオン電池は、一般に大型でかつ高エネルギー容量であるため、より高い安全性の確保が要求され、更には低コストであることが要求される。このような役割を果たすセパレータとして、特許文献１〜４には、乾式法により得られた微多孔性フィルムが提案されている。 Here, a lithium ion battery used for an electric vehicle or a hybrid vehicle is required to have higher output characteristics for taking out a lot of energy in a short time. Moreover, since the lithium ion battery used for such an application is generally large and has a high energy capacity, it is required to ensure higher safety and to be low in cost. As separators that play such a role, Patent Documents 1 to 4 propose microporous films obtained by a dry method.
上記特許文献に記載された乾式法は、抽出液を使用する湿式法と比較して製造工程が簡便でコストの面では優れているものの、得られる微多孔性フィルムの突刺強度が低いという問題がある。最近では、リチウムイオン電池の高容量化の要求の高まりから、より薄い微多孔性フィルムが求められており、薄膜でも高い安全性、低コストを可能にするために突刺強度の確保は重要な課題となっている。
上記事情に鑑み、本発明においては、十分な突刺強度を有し、かつ透過性の良好な微多孔製フィルムを提供することを目的とする。
The dry method described in the above patent document has a problem that the piercing strength of the resulting microporous film is low, although the manufacturing process is simple and excellent in terms of cost compared to the wet method using an extract. is there. Recently, due to the increasing demand for higher capacity lithium ion batteries, thinner microporous films have been demanded, and securing piercing strength is an important issue in order to enable high safety and low cost even for thin films. It has become.
In view of the above circumstances, an object of the present invention is to provide a microporous film having sufficient puncture strength and good permeability.
本発明者らは前述の課題を解決すべく、鋭意検討を重ねた結果、プロピレンとエチレン及び／又はα−オレフィン（例えば、ブテン−１、ヘキセン−１等）を共重合して得られるプロピレン系共重合体を含み、特定範囲のプロピレン含有量及びペンタッド分率を有する微多孔性フィルムが、上記課題を解決し得ることを見出した。 As a result of intensive studies to solve the above-mentioned problems, the present inventors have obtained a propylene-based copolymer obtained by copolymerizing propylene and ethylene and / or α-olefin (for example, butene-1, hexene-1, etc.). It has been found that a microporous film containing a copolymer and having a propylene content in a specific range and a pentad fraction can solve the above problems.
即ち、本発明は以下のとおりである。
［１］
プロピレン含有量が９８〜９９．９ｍｏｌ％であり、ペンタッド分率が９５〜９９．９％であるプロピレン系共重合体を含む微多孔性フィルム。
［２］
重量平均分子量Ｍｗが５０万〜７０万である、上記［１］記載の微多孔性フィルム。
［３］
上記［１］又は［２］に記載の微多孔性フィルムを含む電池用セパレータ。
That is, the present invention is as follows.
[1]
A microporous film containing a propylene-based copolymer having a propylene content of 98 to 99.9 mol% and a pentad fraction of 95 to 99.9%.
[2]
The microporous film according to the above [1], wherein the weight average molecular weight Mw is 500,000 to 700,000.
[3]
The battery separator containing the microporous film as described in said [1] or [2].
本発明によれば、十分な突刺強度を有し、かつ透過性の良好な微多孔製フィルムを提供することができる。 According to the present invention, it is possible to provide a microporous film having sufficient puncture strength and good permeability.
以下、本発明を実施するための形態（以下、単に「本実施形態」という。）について、詳細に説明する。なお、本発明は、以下の本実施形態に限定されるものではなく、その要旨の範囲内で種々変形して実施することができる。 Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as “the present embodiment”) will be described in detail. The present invention is not limited to the following embodiment, and can be implemented with various modifications within the scope of the gist.
〔微多孔性フィルム〕
本実施形態の微多孔性フィルムは、プロピレン含有量が９８〜９９．９ｍｏｌ％であり、ペンタッド分率が９５〜９９．９％であるプロピレン系共重合体を含む微多孔性フィルムである。ここで、プロピレン系共重合体とは、プロピレンとエチレン及び／又はα−オレフィンを共重合して得られる共重合体を言う。α−オレフィンとしては、ブテン−１、ペンテン−１、４−メチル−ペンテン−１、ヘキセン−１、オクテン−１等が挙げられる。
[Microporous film]
The microporous film of this embodiment is a microporous film containing a propylene copolymer having a propylene content of 98 to 99.9 mol% and a pentad fraction of 95 to 99.9%. Here, the propylene-based copolymer refers to a copolymer obtained by copolymerizing propylene and ethylene and / or α-olefin. Examples of the α-olefin include butene-1, pentene-1, 4-methyl-pentene-1, hexene-1, and octene-1.
従来の微多孔性フィルムにはホモポリプロピレンが使用されているが、本発明者らは、０．１〜２．０ｍｏｌ％のエチレンやα−オレフィンをプロピレンと共重合させることにより、透過性を犠牲にすることなく、突刺強度を向上させることができることを見出した。この要因については明らかではないが、エチレンやα−オレフィンがポリプロピレン結晶間をつなぐタイ分子の役割を果たし、結晶間で起こる破壊を抑制しているものと推測される。このような観点から、エチレンやα−オレフィンは、分子鎖中に分散して存在することが好ましく、該プロピレン系共重合体は、ランダム共重合体であることが好ましい。 Homopolypropylene is used for the conventional microporous film, but the present inventors sacrificed permeability by copolymerizing 0.1 to 2.0 mol% of ethylene or α-olefin with propylene. The present inventors have found that the puncture strength can be improved without making a mistake. Although this factor is not clear, it is presumed that ethylene and α-olefin play a role of a tie molecule that connects polypropylene crystals and suppresses the breakage that occurs between the crystals. From such a viewpoint, ethylene and α-olefin are preferably present dispersed in the molecular chain, and the propylene-based copolymer is preferably a random copolymer.
また、本実施形態におけるプロピレン系共重合体のペンタッド分率は、９５〜９９．９％である。ペンタッド分率は分子鎖中のペンタッド単位でのアイソタクティック連鎖の存在割合を示しており、プロピレンモノマー単位が５個連続してメソ結合した連鎖の中心にあるプロピレンモノマー単位の分率である。ペンダット分率はポリプロピレンの立体規則性の指標であり、９５％以上であると延伸時の開孔性が向上し良好な透過性を得ることができる。より好ましいペンタッド分率の下限は、９７％以上であり、更に好ましくは９８％以上である。
ここで、ペンタッド分率は、プロピレン系共重合体を重合する際に用いる触媒や重合条件を適宜選択することにより調整することができる。ペンタッド分率が９５〜９９．９％のプロピレン系重合体を得る方法は、例えば、特開平０５−３２０２４９号公報、特開昭５８−１０４９０５号公報等に例示されている。
Moreover, the pentad fraction of the propylene-based copolymer in the present embodiment is 95 to 99.9%. The pentad fraction indicates the abundance ratio of isotactic chains in pentad units in the molecular chain, and is the fraction of propylene monomer units at the center of a chain in which five propylene monomer units are continuously meso-bonded. The Pendat fraction is an index of the stereoregularity of polypropylene, and when it is 95% or more, the opening property at the time of stretching is improved and good permeability can be obtained. A more preferable lower limit of the pentad fraction is 97% or more, and still more preferably 98% or more.
Here, the pentad fraction can be adjusted by appropriately selecting a catalyst and polymerization conditions used when polymerizing the propylene-based copolymer. Examples of methods for obtaining a propylene polymer having a pentad fraction of 95 to 99.9% are exemplified in JP-A Nos. 05-320249 and 58-104905.
また、プロピレン系共重合体のメルトフローレート（ＭＦＲ）は特に制限されるものではないが、０．１〜５ｇ／１０分であることが好ましく、０．３〜３．０ｇ／１０分であることがより好ましい。ＭＦＲを０．１ｇ／１０分以上とすることで、成形加工時の樹脂の溶融粘度が生産性に適した値となる傾向にあり、一方、５ｇ／１０分以下とすることで、機械的強度が十分な範囲となり実用上問題が発生しにくくなる傾向にある。 Further, the melt flow rate (MFR) of the propylene-based copolymer is not particularly limited, but is preferably 0.1 to 5 g / 10 minutes, and is 0.3 to 3.0 g / 10 minutes. It is more preferable. When the MFR is 0.1 g / 10 min or more, the melt viscosity of the resin at the time of molding tends to be a value suitable for productivity. On the other hand, when the MFR is 5 g / 10 min or less, the mechanical strength is increased. Tends to be in a sufficient range and less likely to cause practical problems.
本実施形態におけるプロピレン系共重合体は、上記の成分の他に本発明の特徴及び効果を損なわない範囲で、必要に応じて他の付加的成分、例えば、オレフィン系エラストマー、酸化防止剤、金属不活性化剤、熱安定剤、難燃剤（有機リン酸エステル系化合物、ポリリン酸アンモニウム系化合物、芳香族ハロゲン系難燃剤、シリコーン系難燃剤等）、フッ素系ポリマー、可塑剤（低分子量ポリエチレン、エポキシ化大豆油、ポリエチレングリコール、脂肪酸エステル類等）、三酸化アンチモン等の難燃助剤、耐候（光）性改良剤、ポリオレフィン用造核剤、スリップ剤、無機又は有機の充填材や強化材（ポリアクリロニトリル繊維、カーボンブラック、酸化チタン、炭酸カルシウム、導電性金属繊維、導電性カーボンブラック等）、各種着色剤、離型剤等を含有してもよい。これらの付加的成分の総含有量は、プロピレン系共重合体１００質量部に対して、２０質量部以下であることが好ましく、より好ましくは１０質量部以下、さらに好ましくは５質量部以下である。 The propylene-based copolymer in the present embodiment is, in addition to the above-described components, other additional components as necessary, for example, olefin-based elastomers, antioxidants, metals, as long as the characteristics and effects of the present invention are not impaired. Deactivator, heat stabilizer, flame retardant (organophosphate ester compound, ammonium polyphosphate compound, aromatic halogen flame retardant, silicone flame retardant, etc.), fluorine polymer, plasticizer (low molecular weight polyethylene, Epoxidized soybean oil, polyethylene glycol, fatty acid esters, etc.), flame retardant aids such as antimony trioxide, weather resistance (light) improvers, polyolefin nucleating agents, slip agents, inorganic or organic fillers and reinforcing materials (Polyacrylonitrile fiber, carbon black, titanium oxide, calcium carbonate, conductive metal fiber, conductive carbon black, etc.), various colors , It may contain a releasing agent. The total content of these additional components is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, and still more preferably 5 parts by mass or less with respect to 100 parts by mass of the propylene-based copolymer. .
〔微多孔性フィルムの製造方法〕
本実施形態の微多孔性フィルムの製造方法としては、特に限定されないが、（Ａ）プロピレン系共重合体を含むフィルム（以下、「原反フィルム」とも言う。）を、−２０℃以上９０℃未満の温度で延伸する冷延伸工程と、（Ｂ）前記冷延伸工程において延伸されたフィルムを９０℃以上１６０℃未満の温度で延伸する熱延伸工程と、を含むことが好ましい。また、延伸倍率は、冷延伸工程では少なくとも一方向に１．０３倍〜１．５倍、熱延伸工程では少なくとも一方向に１．０５倍〜３．０倍とすることが好ましい。
[Method for producing microporous film]
Although it does not specifically limit as a manufacturing method of the microporous film of this embodiment, (A) The film (henceforth a "raw film") containing a propylene-type copolymer is -20 degreeC or more and 90 degreeC. It is preferable to include a cold stretching step of stretching at a temperature lower than (B) and a hot stretching step of stretching the film stretched in the cold stretching step at a temperature of 90 ° C. or higher and lower than 160 ° C. In addition, the draw ratio is preferably 1.03 to 1.5 times in at least one direction in the cold drawing process and 1.05 to 3.0 times in at least one direction in the hot drawing process.
本実施形態におけるプロピレン系共重合体を含む原反フィルムの製造方法としては、Ｔダイ押出成形、インフレーション成形、カレンダー成形、スカイフ法等のシート成形方法を採用し得る。中でも、本実施形態の微多孔性フィルムに要求される物性や用途の観点から、Ｔダイ押出成形が好ましい。 As a method for producing a raw film containing a propylene-based copolymer in the present embodiment, a sheet molding method such as T-die extrusion molding, inflation molding, calendar molding, or Skyf's method may be employed. Among these, T-die extrusion molding is preferable from the viewpoint of physical properties and applications required for the microporous film of the present embodiment.
一方、延伸工程においては、ロール、テンター、オートグラフ等により一軸方向及び／又は二軸方向に延伸する方法を採用し得る。特に、本実施形態の微多孔性フィルムに要求される物性や用途の観点から、ロールによる２段階以上の一軸延伸が好ましい。 On the other hand, in the stretching step, a method of stretching in a uniaxial direction and / or a biaxial direction by a roll, a tenter, an autograph or the like can be adopted. In particular, from the viewpoint of physical properties and applications required for the microporous film of the present embodiment, two or more stages of uniaxial stretching with a roll are preferable.
原反フィルムの製造方法において、押出し後のドロー比、即ち、フィルムの巻取速度（単位：ｍ／分）をプロピレン系共重合体の押出速度（ダイリップを通過する溶融樹脂の流れ方向の線速度。単位：ｍ／分）で除した値は、好ましくは１０〜５００、より好ましくは３０〜３００、更に好ましくは７５〜２５０である。また、原反フィルムを巻き取る際のフィルムの巻取速度は、好ましくは約２〜４００ｍ／分、より好ましくは１０〜２００ｍ／分である。ドロー比を上記範囲とすることは、得られる微多孔性フィルムの透過性を向上させる観点から好適である。透過性が良好な微多孔性フィルムを得るためには、用いるプロピレン系共重合体のＭＦＲに応じてドロー比を変更することが望ましい。例えば、ＭＦＲが０．１〜１．０のプロピレン系共重合体の場合、ドロー比を７５〜１５０にすることが好ましく、ＭＦＲが１．０〜５．０のプロピレン系共重合体の場合、ドロー比を１００〜２５０にすることが好ましい。 In the raw film production method, the draw ratio after extrusion, that is, the film winding speed (unit: m / min) is the propylene copolymer extrusion speed (linear velocity in the flow direction of the molten resin passing through the die lip). (Unit: m / min) is preferably 10 to 500, more preferably 30 to 300, and still more preferably 75 to 250. Moreover, the winding speed of the film when winding the raw film is preferably about 2 to 400 m / min, more preferably 10 to 200 m / min. Setting the draw ratio in the above range is preferable from the viewpoint of improving the permeability of the obtained microporous film. In order to obtain a microporous film with good permeability, it is desirable to change the draw ratio according to the MFR of the propylene-based copolymer used. For example, in the case of a propylene copolymer having an MFR of 0.1 to 1.0, the draw ratio is preferably 75 to 150, and in the case of a propylene copolymer having an MFR of 1.0 to 5.0, The draw ratio is preferably 100 to 250.
（熱処理工程）
上記のようにして製造された原反フィルムには、後述する冷延伸工程の前に必要に応じて熱処理（アニール）を施すことが好ましい。アニールの方法としては、例えば、原反フィルムを加熱ロール上に接触させる方法、巻き取る前に加熱気相中に曝す方法、原反フィルムを芯体上に巻き取り加熱気相又は加熱液相中に曝す方法、並びにこれらを組み合わせて行う方法が挙げられる。これらのアニールの条件は、例えば、１２０℃以上１６０℃未満の加熱温度で、１０秒間〜１００時間アニールすることが好ましい。加熱温度が１２０℃以上であると、得られる微多孔性フィルムの透過性が更に良好となる傾向にあり、１６０℃未満であると、原反フィルムを芯体上に巻き取った状態でアニールしてもフィルム同士が融着し難くなる傾向にある。アニールの際の加熱温度は１３５℃〜１５５℃にすることがより好ましい。このような温度範囲でアニールを行うと、原反フィルムの結晶化度が高まり、透過性が良好な微多孔性フィルムが得られる傾向にある。
(Heat treatment process)
The raw film produced as described above is preferably subjected to heat treatment (annealing) as necessary before the cold drawing step described later. As an annealing method, for example, a method in which a raw film is brought into contact with a heated roll, a method in which the raw film is exposed to a heated gas phase before winding, a raw film is wound on a core body in a heated gas phase or a heated liquid phase. And a method of combining these methods. The annealing conditions are preferably, for example, annealing at a heating temperature of 120 ° C. or higher and lower than 160 ° C. for 10 seconds to 100 hours. When the heating temperature is 120 ° C. or higher, the permeability of the resulting microporous film tends to be further improved. When the heating temperature is lower than 160 ° C., the raw film is annealed in a state of being wound on the core. However, the films tend to be difficult to fuse. The heating temperature during annealing is more preferably 135 ° C. to 155 ° C. When annealing is performed in such a temperature range, the degree of crystallinity of the raw film increases, and a microporous film having good permeability tends to be obtained.
（冷延伸工程）
次に、冷延伸工程について説明する。冷延伸工程においては、プロピレン系共重合体を含むフィルムを、−２０℃以上９０℃未満の温度で延伸する。冷延伸工程においては、上記のようにして原反フィルムに熱処理を施した後、好ましくは−２０℃以上９０℃未満に保持した状態で、少なくとも一方向に１．０３倍〜１．５倍に冷延伸することが好ましい。
(Cold drawing process)
Next, the cold drawing process will be described. In the cold stretching step, the film containing the propylene-based copolymer is stretched at a temperature of −20 ° C. or higher and lower than 90 ° C. In the cold drawing step, after heat-treating the raw film as described above, it is preferably 1.03 times to 1.5 times in at least one direction in a state of being kept at -20 ° C or higher and lower than 90 ° C. Cold drawing is preferred.
冷延伸工程における冷延伸の延伸温度は、好ましくは−２０℃以上９０℃未満、より好ましくは０℃以上５０℃以下の温度である。−２０℃以上で延伸することにより、微多孔性フィルムが破断し難くなる傾向にあり、９０℃未満で延伸することにより、得られる微多孔性フィルムの透過性がより良好となる傾向にある。ここで、冷延伸の延伸温度は冷延伸工程におけるフィルムの表面温度を示す。また、フィルムの表面温度は、非接触系の熱電対を延伸ロール機内に設けることにより測定することができる。 The stretching temperature for cold stretching in the cold stretching step is preferably -20 ° C or higher and lower than 90 ° C, more preferably 0 ° C or higher and 50 ° C or lower. By stretching at −20 ° C. or higher, the microporous film tends to be difficult to break, and by stretching below 90 ° C., the resulting microporous film tends to have better permeability. Here, the drawing temperature of cold drawing shows the surface temperature of the film in the cold drawing process. The surface temperature of the film can be measured by providing a non-contact type thermocouple in the stretching roll machine.
冷延伸工程における冷延伸の延伸倍率は、好ましくは１．０３倍以上１．５倍以下であり、より好ましくは１．０５倍以上１．３倍以下である。延伸倍率が、１．０３倍以上であると、透過性が良好となる傾向にあり、１．５倍以下であると、突刺強度が良好となる傾向にある。より好ましい延伸倍率は、１．０５倍〜１．３倍である。原反フィルムの冷延伸は、少なくとも一方向に行い、二方向に行ってもよいが、好ましくは、フィルムの押出し方向（以下「ＭＤ方向」とも言う。）にのみ一軸延伸を行う。
本実施形態における冷延伸工程においては、原反フィルムを、０℃以上５０℃以下の温度で、ＭＤ方向に１．０５倍〜１．３倍に一軸延伸することが特に好ましい。
The draw ratio of cold drawing in the cold drawing step is preferably 1.03 times or more and 1.5 times or less, more preferably 1.05 times or more and 1.3 times or less. When the draw ratio is 1.03 times or more, the permeability tends to be good, and when it is 1.5 times or less, the puncture strength tends to be good. A more preferable draw ratio is 1.05 times to 1.3 times. The cold stretch of the raw film may be performed in at least one direction and may be performed in two directions. Preferably, the original film is uniaxially stretched only in the film extrusion direction (hereinafter also referred to as “MD direction”).
In the cold stretching step in the present embodiment, it is particularly preferable that the original film is uniaxially stretched in the MD direction by 1.05 to 1.3 times at a temperature of 0 ° C. or more and 50 ° C. or less.
（熱延伸工程）
次に、熱延伸工程について説明する。熱延伸工程においては、前記冷延伸工程において延伸されたフィルムを９０℃以上１６０℃未満の温度で延伸する。熱延伸工程においては、上記のようにして冷延伸を行った後、フィルムを９０℃以上１６０℃未満に保持した状態で、少なくとも一方向に１．０５倍以上３．０倍以下に熱延伸することが好ましい。
(Heat drawing process)
Next, the heat stretching process will be described. In the hot stretching step, the film stretched in the cold stretching step is stretched at a temperature of 90 ° C. or higher and lower than 160 ° C. In the hot stretching process, after performing cold stretching as described above, the film is hot stretched at least 1.05 times to 3.0 times in at least one direction with the film held at 90 ° C. or higher and lower than 160 ° C. It is preferable.
熱延伸の延伸温度は、好ましくは９０℃以上１６０℃未満、より好ましくは１２０℃以上１５０℃以下の温度である。９０℃以上で熱延伸すると、フィルムが破断し難くなる傾向にあり、１６０℃未満で熱延伸すると、得られる微多孔性フィルムの透過性が良好となる傾向にある。ここで、熱延伸の延伸温度は熱延伸工程におけるフィルムの表面温度を示す。 The stretching temperature of the heat stretching is preferably 90 ° C. or higher and lower than 160 ° C., more preferably 120 ° C. or higher and 150 ° C. or lower. When stretched at 90 ° C. or higher, the film tends to be difficult to break, and when stretched below 160 ° C., the resulting microporous film tends to have good permeability. Here, the stretching temperature of the heat stretching indicates the surface temperature of the film in the heat stretching process.
熱延伸工程における熱延伸の延伸倍率は、好ましくは１．０５倍以上３．０倍以下であり、より好ましくは１．５倍以上２．５倍以下である。熱延伸工程における延伸倍率が１．０５倍以上であると、透過性の良好な微多孔性フィルムが得られる傾向にあり、３．０倍以下であると、突刺強度が良好となる傾向にある。熱延伸は、少なくとも一方向に対して行い、二方向に行ってもよいが、好ましくは冷延伸の延伸方向と同じ方向に行い、より好ましくは冷延伸の延伸方向と同じ方向にのみ一軸延伸を行う。
本実施形態における熱延伸工程においては、冷延伸工程により冷延伸されたフィルムを、１００℃以上１５０℃以下の温度で、ＭＤ方向に１．５倍〜２．５倍に一軸延伸することが特に好ましい。
The draw ratio of the heat drawing in the heat drawing step is preferably 1.05 to 3.0 times, more preferably 1.5 to 2.5 times. When the draw ratio in the heat drawing process is 1.05 times or more, a microporous film having good permeability tends to be obtained, and when it is 3.0 times or less, the puncture strength tends to be good. . The hot stretching may be performed in at least one direction and may be performed in two directions, but is preferably performed in the same direction as the cold stretching direction, more preferably uniaxial stretching only in the same direction as the cold stretching direction. Do.
In the hot stretching process in the present embodiment, the film cold-drawn by the cold-stretching process is particularly preferably uniaxially stretched 1.5 to 2.5 times in the MD direction at a temperature of 100 ° C. or higher and 150 ° C. or lower. preferable.
本実施形態の微多孔性フィルムの製造方法は、微多孔性フィルムに要求される良好な透過性や用途の観点から、冷延伸工程と熱延伸工程との２段階の延伸工程を含む。微多孔性フィルムの製造方法が延伸工程を１段階で行う方法である場合、得られる微多孔性フィルムは、要求される良好な透過性を満たし難くなる。なお、本実施形態の微多孔性フィルムの製造方法は、上述の各延伸工程に加えて、更なる延伸工程を含んでもよい。 The manufacturing method of the microporous film of the present embodiment includes a two-stage stretching process, which is a cold stretching process and a hot stretching process, from the viewpoint of good permeability and use required for the microporous film. When the manufacturing method of a microporous film is a method which performs an extending | stretching process in 1 step, the obtained microporous film becomes difficult to satisfy | fill the required favorable permeability | transmittance. In addition, the manufacturing method of the microporous film of this embodiment may include the further extending process in addition to each above-mentioned extending process.
（熱固定工程）
本実施形態の微多孔性フィルムの製造方法は、熱延伸工程を経て得られた微多孔性フィルムに対して、好ましくはアニール温度より０℃以上４０℃未満高い温度で熱処理を施す熱固定工程を含むことが好ましい。この熱固定の方法としては、熱固定後の微多孔性フィルムの長さが、熱固定前の微多孔性フィルムの長さに対して３〜５０％減少する程度熱収縮させる方法（以下、この方法を「緩和」と言う。）、延伸方向の寸法が変化しないように熱固定する方法等が挙げられる。この熱固定によって寸法安定性のより一層良好な、即ち熱収縮率の小さい微多孔性フィルムとすることができる。
(Heat setting process)
The method for producing a microporous film of the present embodiment includes a heat setting step in which heat treatment is performed on the microporous film obtained through the heat stretching step, preferably at a temperature higher than the annealing temperature by 0 ° C. or more and less than 40 ° C. It is preferable to include. This heat setting method includes a method of heat shrinking to such an extent that the length of the microporous film after heat setting is reduced by 3 to 50% with respect to the length of the microporous film before heat setting (hereinafter referred to as this method). The method is referred to as “relaxation”), and a method of heat setting so that the dimension in the stretching direction does not change. By this heat setting, it is possible to obtain a microporous film having much better dimensional stability, that is, having a small heat shrinkage rate.
熱固定温度は、１２０℃以上１６０℃以下であることが好ましく、１３０℃以上１６０℃以下であることがより好ましい。ここで、熱固定温度とは、熱固定工程における微多孔性フィルムの表面温度を示す。 The heat setting temperature is preferably 120 ° C. or higher and 160 ° C. or lower, and more preferably 130 ° C. or higher and 160 ° C. or lower. Here, the heat setting temperature indicates the surface temperature of the microporous film in the heat setting process.
上記のように、プロピレン系共重合体を含むフィルムの製造工程、必要に応じて熱処理工程を経た後、冷延伸工程、熱延伸工程を経て、さらに必要に応じて熱固定工程を経る製造方法により、目的とする微多孔性フィルムを得ることができる。 As described above, by a production method of a film containing a propylene-based copolymer, after undergoing a heat treatment step as necessary, through a cold drawing step, a hot drawing step, and further through a heat setting step as necessary The intended microporous film can be obtained.
（重量平均分子量）
本実施形態における微多孔性フィルムの重量平均分子量Ｍｗは５０万〜７０万であることが好ましい。Ｍｗが５０万以上であると、フィルムの強度が良好となる傾向にあり、分子量が７０万以下であると、熱収縮率が良好となる傾向にある。微多孔性フィルムの重量平均分子量は、より好ましくは５５万〜６５万である。
(Weight average molecular weight)
The weight average molecular weight Mw of the microporous film in this embodiment is preferably 500,000 to 700,000. When the Mw is 500,000 or more, the strength of the film tends to be good, and when the molecular weight is 700,000 or less, the thermal shrinkage tends to be good. The weight average molecular weight of the microporous film is more preferably 550,000 to 650,000.
（気孔率）
本実施形態における微多孔性フィルムの気孔率は３５％〜５５％が好ましく、より好ましくは４５％〜５０％である。気孔率が３５％以上であると、微多孔性フィルムを電池用セパレータとして用いた場合に、十分なイオン透過性を確保し得る傾向にある。一方、気孔率が５５％以下であると、微多孔性フィルムが十分な引裂き強度を確保し得る傾向にある。
なお、微多孔性フィルムの気孔率は、プロピレン系共重合体の組成、各延伸工程における延伸温度、延伸倍率等を適宜設定することにより上述の範囲に調整することができる。例えば、気孔率を高くするには、原反フィルムを成形する際のドロー比を高くしたり、延伸倍率を高くしたりすればよい。また、微多孔性フィルムの気孔率は、そのフィルムから１０ｃｍ×１０ｃｍ角のサンプルを切り出し、そのサンプルの体積Ｖ（ｃｍ3）及び質量Ｍ（ｇ）と、フィルムを構成する樹脂組成物Ａｃの密度ｄ（ｇ／ｃｍ3）とから下記式を用いて算出される。
気孔率（％）＝｛（Ｖ−Ｍ／ｄ）／Ｖ｝×１００
(Porosity)
The porosity of the microporous film in this embodiment is preferably 35% to 55%, more preferably 45% to 50%. When the porosity is 35% or more, when a microporous film is used as a battery separator, sufficient ion permeability tends to be ensured. On the other hand, when the porosity is 55% or less, the microporous film tends to ensure sufficient tear strength.
The porosity of the microporous film can be adjusted to the above range by appropriately setting the composition of the propylene copolymer, the stretching temperature in each stretching step, the stretching ratio, and the like. For example, in order to increase the porosity, the draw ratio at the time of forming the raw film may be increased or the draw ratio may be increased. Moreover, the porosity of a microporous film cuts out the sample of 10 cm x 10 cm square from the film, the volume V (cm < 3 >) and mass M (g) of the sample, and the density of resin composition Ac which comprises a film Calculated from d (g / cm 3 ) using the following formula.
Porosity (%) = {(VM−d / V) × 100
（透気度）
本実施形態における微多孔性フィルムの透気度は、１０秒／１００ｃｃ〜１０００秒／１００ｃｃであることが好ましい。より好ましくは５０秒／１００ｃｃ〜８００秒／１００ｃｃ、更に好ましくは１００秒／１００ｃｃ〜３００秒／１００ｃｃである。透気度が１０００秒／１００ｃｃ以下であると、微多孔性フィルムが十分なイオン透過性を確保し得る傾向にある。一方、透気度が１０秒／１００ｃｃ以上であると、欠陥のない、より均質な微多孔性フィルムが得られる傾向にある。
なお、微多孔性フィルムの透気度は、プロピレン系共重合体の組成、各延伸工程における延伸温度、延伸倍率等を適宜設定することにより上述の範囲に調整することができる。例えば、透気度を高くするには、延伸倍率を高くしたり、熱固定における緩和倍率を低くすればよい。
(Air permeability)
The air permeability of the microporous film in the present embodiment is preferably 10 seconds / 100 cc to 1000 seconds / 100 cc. More preferably, it is 50 seconds / 100cc-800 seconds / 100cc, More preferably, it is 100 seconds / 100cc-300 seconds / 100cc. When the air permeability is 1000 sec / 100 cc or less, the microporous film tends to ensure sufficient ion permeability. On the other hand, when the air permeability is 10 seconds / 100 cc or more, there is a tendency that a more uniform microporous film without defects is obtained.
The air permeability of the microporous film can be adjusted to the above range by appropriately setting the composition of the propylene-based copolymer, the stretching temperature in each stretching step, the stretching ratio, and the like. For example, in order to increase the air permeability, the stretch ratio may be increased or the relaxation ratio in heat setting may be decreased.
（膜厚）
本実施形態における微多孔性フィルムの膜厚は、好ましくは５〜４０μｍ、より好ましくは１０〜３０μｍである。
(Film thickness)
The film thickness of the microporous film in this embodiment is preferably 5 to 40 μm, more preferably 10 to 30 μm.
本実施形態における微多孔性フィルムは、精密濾過膜、電池用セパレータ、コンデンサー用セパレータ、燃料電池用材料などに使用することができ、特にリチウムイオン電池用セパレータとして好適に使用することができる。 The microporous film in this embodiment can be used for a microfiltration membrane, a battery separator, a capacitor separator, a fuel cell material, and the like, and can be particularly suitably used as a lithium ion battery separator.
なお、本明細書中の各物性は、特に明記しない限り、以下の実施例に記載された方法に準じて測定することができる。 In addition, each physical property in this specification can be measured according to the method described in the following Examples, unless otherwise specified.
次に、実施例及び比較例を挙げてより具体的に説明するが、本発明は、以下の実施例に限定されるものではない。
なお、実施例及び比較例における各種特性の評価法については以下のとおりである。
Next, although an example and a comparative example are given and explained more concretely, the present invention is not limited to the following examples.
In addition, about the evaluation method of the various characteristics in an Example and a comparative example, it is as follows.
（１）ＭＦＲ
プロピレン系共重合体のＭＦＲは、ＪＩＳ Ｋ７２１０に準拠して、温度２１０℃、荷重２．１６ｋｇの条件で測定した値であり、その単位はｇ／１０分である。
(２）ペンタッド分率（％）
プロピレン系共重合体のペンタッド分率は、高分子分析ハンドブック（日本分析化学会編集）の記載に基づいて帰属した１３Ｃ−ＮＭＲスペクトルから、ピーク高さ法によって算出した。１３Ｃ−ＮＭＲスペクトルの測定は、日本電子（株）製ＥＣＳ−４００を使用して、微多孔性フィルムをｏ−ジクロロベンゼン−ｄに溶解させ、測定温度１３０℃、積算回数１００００回の条件で行った。
(1) MFR
The MFR of the propylene-based copolymer is a value measured under conditions of a temperature of 210 ° C. and a load of 2.16 kg in accordance with JIS K7210, and the unit is g / 10 minutes.
(2) Pentad fraction (%)
The pentad fraction of the propylene-based copolymer was calculated by a peak height method from a 13C-NMR spectrum assigned based on the description in the Polymer Analysis Handbook (edited by the Analytical Society of Japan). The 13C-NMR spectrum was measured using ECS-400 manufactured by JEOL Ltd., and the microporous film was dissolved in o-dichlorobenzene-d under the conditions of a measurement temperature of 130 ° C. and a cumulative number of 10,000 times. It was.
(３）プロピレン含有量（％）
プロピレン系共重合体のプロピレン含有量は、高分子分析ハンドブック（日本分析化学会編集）の記載に基づいて帰属した１３Ｃ−ＮＭＲスペクトルから、ピーク高さ法によって算出した。１３Ｃ−ＮＭＲスペクトルの測定は、日本電子（株）製ＥＣＳ−４００を使用して、微多孔性フィルムをｏ−ジクロロベンゼン−ｄに溶解させ、測定温度１３０℃、積算回数１００００回の条件で行った。
(3) Propylene content (%)
The propylene content of the propylene-based copolymer was calculated by the peak height method from the 13C-NMR spectrum assigned based on the description in the Polymer Analysis Handbook (edited by the Analytical Society of Japan). The 13C-NMR spectrum was measured using ECS-400 manufactured by JEOL Ltd., and the microporous film was dissolved in o-dichlorobenzene-d under the conditions of a measurement temperature of 130 ° C. and a cumulative number of 10,000 times. It was.
（４）重量平均分子量
微多孔性フィルムの分子量分布は、ゲル・パーミエーション・クロマトグラフィー（ＧＰＣ）から求められる重量平均分子量（Ｍｗ）と数平均分子量（Ｍｎ）との比Ｍｗ／Ｍｎの値として算出した。ＧＰＣ測定は、東ソー社製のＧＰＳ装置（商品名「ＨＬＣ−８１２１ＧＰＣ／ＨＴ」）を用いて行った。カラムとしては東ソー社製の商品名「ＴＳＫｇｅｌ ＧＭＨＨＲ−Ｈ（２０）」（２本）を用い、移動相ｏ−ジクロロベンゼン（ｏ−ＤＣＢ）、カラム温度１５５℃、流量１．０ｍＬ／分、試料濃度０．５ｍｇ／ｍＬ（ｏ−ＤＣＢ）、注入量５００μＬ、試料溶解温度１６０℃、試料溶解時間３時間の条件で行った。分子量の校正は、ポリスチレンで行い、ポリスチレン換算分子量で重量平均分子量Ｍｗ及びＭｎを求めた。
(4) Weight average molecular weight The molecular weight distribution of the microporous film is the value of the ratio Mw / Mn between the weight average molecular weight (Mw) and the number average molecular weight (Mn) determined from gel permeation chromatography (GPC). Calculated. The GPC measurement was performed using a GPS device (trade name “HLC-8121GPC / HT”) manufactured by Tosoh Corporation. As the column, trade name “TSKgel GMHHR-H (20)” (2) manufactured by Tosoh Corporation was used, mobile phase o-dichlorobenzene (o-DCB), column temperature 155 ° C., flow rate 1.0 mL / min, sample The concentration was 0.5 mg / mL (o-DCB), the injection amount was 500 μL, the sample dissolution temperature was 160 ° C., and the sample dissolution time was 3 hours. The molecular weight was calibrated with polystyrene, and the weight average molecular weights Mw and Mn were determined in terms of polystyrene equivalent molecular weight.
（５）膜厚（μｍ）
微多孔性フィルムの膜厚は、ダイヤルゲージ（尾崎製作所社製、商品名「ＰＥＡＣＯＣＫ Ｎｏ．２５」）を用いて測定した。
(5) Film thickness (μm)
The film thickness of the microporous film was measured using a dial gauge (manufactured by Ozaki Seisakusho, trade name “PEACOCK No. 25”).
（６）透気度（秒／１００ｃｃ）
微多孔性フィルムの透気度は、ＪＩＳ Ｐ−８１１７に準拠したガーレー式透気度計により測定した。なお、微多孔性フィルムの膜厚を２０μｍとした場合の値に換算した値を、微多孔性フィルムの透気度とした。
(6) Air permeability (sec / 100cc)
The air permeability of the microporous film was measured with a Gurley type air permeability meter based on JIS P-8117. In addition, the value converted into the value when the film thickness of a microporous film was 20 micrometers was made into the air permeability of a microporous film.
（７）気孔率（％）
微多孔性フィルムの気孔率は、微多孔性フィルムから１０ｃｍ×１０ｃｍ角のサンプルを切り出し、そのサンプルの体積Ｖ（ｃｍ3）及び質量Ｍ（ｇ）と、フィルムを構成する樹脂組成物の密度０．９１（ｇ／ｃｍ3）とから下記式を用いて算出した。
気孔率（％）＝｛（Ｖ−Ｍ／０．９１）／Ｖ｝×１００
（８）突刺強度（ｇ）
カトーテック製「ＫＥＳ−Ｇ５ハンディー圧縮試験器」（商標）を用いて、針先端の曲率半径０.５ｍｍ、突き刺し速度２ｍｍ／ｓｅｃの条件で突き刺し試験を行い、最大突き刺し荷重（ｇ）を測定した。
（９）熱収縮率（％）
フィルムから１２ｃｍ×１２ｃｍ角のサンプルを切り出し、そのサンプルのＭＤ方向に１０ｃｍ間隔で２つの印を付け、サンプルを紙で挟んだ状態で、１００℃のオーブン中に６０分間静置した。オーブンからサンプルを取り出し冷却した後、印間の長さ（ｃｍ）を測定し、下記式にてＭＤ方向の熱収縮率を算出した。
熱収縮率（％）＝（１０−加熱後の印間の長さ（ｃｍ））／１０×１００
(7) Porosity (%)
The porosity of the microporous film was determined by cutting a 10 cm × 10 cm square sample from the microporous film, and the volume V (cm 3 ) and mass M (g) of the sample and the density of the resin composition constituting the film was 0. .91 (g / cm 3 ) and the following formula was used.
Porosity (%) = {(VM−0.91) / V} × 100
(8) Puncture strength (g)
Using a “KES-G5 Handy Compression Tester” (trademark) manufactured by Kato Tech, a piercing test was conducted under the conditions of a radius of curvature of the needle tip of 0.5 mm and a piercing speed of 2 mm / sec, and the maximum piercing load (g) was measured. .
(9) Thermal contraction rate (%)
A sample of 12 cm × 12 cm square was cut out from the film, two marks were made at 10 cm intervals in the MD direction of the sample, and the sample was placed in a 100 ° C. oven for 60 minutes while being sandwiched between paper. After removing the sample from the oven and cooling, the length (cm) between the marks was measured, and the thermal shrinkage in the MD direction was calculated by the following formula.
Thermal contraction rate (%) = (10−length between marks after heating (cm)) / 10 × 100
使用したプロピレン系共重合体（Ａ）〜（Ｉ）、（Ｋ）〜（Ｍ）は、いずれもプロピレンとエチレンの共重合体であり、ＭＦＲ、プロピレン含有量、ペンタッド分率は、表１に示すとおりである。また、プロピレン系共重合体（Ｊ）は、プロピレンとブテン−１の共重合体であり、比較例４に用いたプロピレン系共重合体（Ｎ）は、ホモポリプロピレンである。 The propylene-based copolymers (A) to (I) and (K) to (M) used are all copolymers of propylene and ethylene. The MFR, propylene content, and pentad fraction are shown in Table 1. It is shown. The propylene copolymer (J) is a copolymer of propylene and butene-1, and the propylene copolymer (N) used in Comparative Example 4 is homopolypropylene.
〔実施例１〕
プロピレン系共重合体（Ａ）を、口径２０ｍｍ、Ｌ／Ｄ＝３０の単軸押出機にフィーダーを介して投入し、押出機先端に設置したリップ厚み４．０ｍｍのＴダイから押出した。押出機のシリンダー温度（「押出温度」とも言う）は２２０℃に、Ｔダイの温度（「成膜温度」とも言う）は２００℃に設定した。押出した後の溶融したポリプロピレン樹脂に直ちに２５℃の冷風を当て、次いで、９５℃に冷却したキャストロールでドロー比２００、巻き取り速度１５ｍ／分の条件で巻き取り、原反フィルムを得た。
[Example 1]
The propylene copolymer (A) was introduced into a single screw extruder having a diameter of 20 mm and L / D = 30 via a feeder, and extruded from a T die having a lip thickness of 4.0 mm installed at the tip of the extruder. The cylinder temperature (also referred to as “extrusion temperature”) of the extruder was set to 220 ° C., and the temperature of the T die (also referred to as “film formation temperature”) was set to 200 ° C. 25 ° C. cold air was immediately applied to the melted polypropylene resin after extrusion, and the film was then wound with a cast roll cooled to 95 ° C. under the conditions of a draw ratio of 200 and a winding speed of 15 m / min.
得られた原反フィルム２００ｍを芯体上に巻き取った状態で、１４０℃の温度で５時間アニールした後、２５℃まで冷却し、２５℃の温度でＭＤ方向に１．３倍に一軸延伸（冷延伸工程）し、続いて、１３０℃の温度でＭＤ方向に２．５倍に一軸延伸（熱延伸工程）し、更に、１４５℃の温度で０．９倍に緩和させて熱固定を施し、微多孔性フィルムを得た。得られた微多孔性フィルムについて、重量平均分子量、膜厚、透気度、気孔率、突刺強度、熱収縮率を測定した。その結果を表１に示す。 The obtained raw film 200m was wound on the core body, annealed at a temperature of 140 ° C for 5 hours, cooled to 25 ° C, and uniaxially stretched 1.3 times in the MD direction at a temperature of 25 ° C. (Cold stretching process), followed by uniaxial stretching in the MD direction at a temperature of 130 ° C. (heat stretching process) 2.5 times, and further relaxation by 0.9 times at a temperature of 145 ° C. And a microporous film was obtained. About the obtained microporous film, the weight average molecular weight, the film thickness, the air permeability, the porosity, the puncture strength, and the heat shrinkage rate were measured. The results are shown in Table 1.
〔実施例２〜１０、比較例１〜４〕
表１に記載した条件以外は実施例１と同様にして、実施例２〜９及び比較例1〜４の微多孔性フィルムを得た。得られた微多孔性フィルムについて、諸物性を評価した結果を表１に示す。実施例１〜１０は、いずれも透過性と突刺強度が良好であるのに対し、比較例１〜３は透過性が劣り、比較例４は突刺強度が劣っていた。
[Examples 2 to 10, Comparative Examples 1 to 4]
Except for the conditions described in Table 1, the microporous films of Examples 2 to 9 and Comparative Examples 1 to 4 were obtained in the same manner as Example 1. Table 1 shows the results of evaluating various physical properties of the obtained microporous film. Examples 1 to 10 all had good permeability and puncture strength, while Comparative Examples 1 to 3 had poor permeability and Comparative Example 4 had poor puncture strength.
本発明の微多孔性フィルムは、電池用セパレータ、より具体的には、リチウム二次電池用セパレータとしての産業上利用可能性を有する。 The microporous film of the present invention has industrial applicability as a battery separator, more specifically as a lithium secondary battery separator.
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| JP2016128533A (en) * | 2015-01-09 | 2016-07-14 | Jnc株式会社 | Microporous film and manufacturing method therefor |
| JP2016128532A (en) * | 2015-01-09 | 2016-07-14 | Jnc株式会社 | Microporous film and manufacturing method therefor |
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