JP2013070006A - Heat resistance separator for power storage device, and method of manufacturing the same - Google Patents
Heat resistance separator for power storage device, and method of manufacturing the same Download PDFInfo
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- 238000003860 storage Methods 0.000 title claims abstract description 44
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 22
- 239000000843 powder Substances 0.000 claims abstract description 104
- 229920005672 polyolefin resin Polymers 0.000 claims abstract description 55
- 239000005011 phenolic resin Substances 0.000 claims abstract description 42
- 239000000203 mixture Substances 0.000 claims abstract description 34
- 238000004898 kneading Methods 0.000 claims abstract description 18
- 239000011148 porous material Substances 0.000 claims abstract description 16
- 239000004014 plasticizer Substances 0.000 claims description 35
- 239000002994 raw material Substances 0.000 claims description 29
- 230000005611 electricity Effects 0.000 claims description 24
- 239000005486 organic electrolyte Substances 0.000 claims description 6
- 239000011255 nonaqueous electrolyte Substances 0.000 claims description 5
- 238000005338 heat storage Methods 0.000 claims 1
- 229920000098 polyolefin Polymers 0.000 abstract description 24
- 230000000694 effects Effects 0.000 abstract description 21
- 239000000463 material Substances 0.000 abstract description 16
- 239000003795 chemical substances by application Substances 0.000 abstract description 7
- 238000012986 modification Methods 0.000 abstract description 5
- 230000004048 modification Effects 0.000 abstract description 5
- 230000001747 exhibiting effect Effects 0.000 abstract 1
- 239000011800 void material Substances 0.000 abstract 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 36
- 229920005989 resin Polymers 0.000 description 31
- 239000011347 resin Substances 0.000 description 31
- 238000000034 method Methods 0.000 description 27
- 239000000377 silicon dioxide Substances 0.000 description 18
- 229920001903 high density polyethylene Polymers 0.000 description 16
- 239000004700 high-density polyethylene Substances 0.000 description 16
- -1 polyethylene Polymers 0.000 description 14
- 230000000052 comparative effect Effects 0.000 description 12
- 239000003990 capacitor Substances 0.000 description 10
- 239000002480 mineral oil Substances 0.000 description 10
- 235000010446 mineral oil Nutrition 0.000 description 10
- 239000004094 surface-active agent Substances 0.000 description 10
- 238000001125 extrusion Methods 0.000 description 8
- 239000010690 paraffinic oil Substances 0.000 description 8
- 230000007423 decrease Effects 0.000 description 7
- 239000008151 electrolyte solution Substances 0.000 description 7
- 230000001965 increasing effect Effects 0.000 description 7
- 229920003986 novolac Polymers 0.000 description 7
- KXGFMDJXCMQABM-UHFFFAOYSA-N 2-methoxy-6-methylphenol Chemical compound [CH]OC1=CC=CC([CH])=C1O KXGFMDJXCMQABM-UHFFFAOYSA-N 0.000 description 6
- 229920001568 phenolic resin Polymers 0.000 description 6
- 238000002844 melting Methods 0.000 description 5
- 230000008018 melting Effects 0.000 description 5
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 5
- 239000003960 organic solvent Substances 0.000 description 5
- 238000011282 treatment Methods 0.000 description 5
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 4
- 239000000654 additive Substances 0.000 description 4
- 230000015572 biosynthetic process Effects 0.000 description 4
- 239000003792 electrolyte Substances 0.000 description 4
- 238000010894 electron beam technology Methods 0.000 description 4
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- 239000002904 solvent Substances 0.000 description 4
- 239000004698 Polyethylene Substances 0.000 description 3
- 230000007547 defect Effects 0.000 description 3
- 238000010438 heat treatment Methods 0.000 description 3
- QSHDDOUJBYECFT-UHFFFAOYSA-N mercury Chemical compound [Hg] QSHDDOUJBYECFT-UHFFFAOYSA-N 0.000 description 3
- 229910052753 mercury Inorganic materials 0.000 description 3
- 239000004745 nonwoven fabric Substances 0.000 description 3
- 229920000573 polyethylene Polymers 0.000 description 3
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- IMNFDUFMRHMDMM-UHFFFAOYSA-N N-Heptane Chemical compound CCCCCCC IMNFDUFMRHMDMM-UHFFFAOYSA-N 0.000 description 2
- 239000004743 Polypropylene Substances 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 230000000996 additive effect Effects 0.000 description 2
- 150000003973 alkyl amines Chemical class 0.000 description 2
- 239000003945 anionic surfactant Substances 0.000 description 2
- 239000003093 cationic surfactant Substances 0.000 description 2
- 239000004927 clay Substances 0.000 description 2
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 2
- 235000014113 dietary fatty acids Nutrition 0.000 description 2
- 239000000194 fatty acid Substances 0.000 description 2
- 229930195729 fatty acid Natural products 0.000 description 2
- 239000010419 fine particle Substances 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- BKIMMITUMNQMOS-UHFFFAOYSA-N nonane Chemical compound CCCCCCCCC BKIMMITUMNQMOS-UHFFFAOYSA-N 0.000 description 2
- 239000002736 nonionic surfactant Substances 0.000 description 2
- GLDOVTGHNKAZLK-UHFFFAOYSA-N octadecan-1-ol Chemical compound CCCCCCCCCCCCCCCCCCO GLDOVTGHNKAZLK-UHFFFAOYSA-N 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229920000306 polymethylpentene Polymers 0.000 description 2
- 239000011116 polymethylpentene Substances 0.000 description 2
- 229920001155 polypropylene Polymers 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 229930195734 saturated hydrocarbon Natural products 0.000 description 2
- 238000012360 testing method Methods 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- YKZUNWLMLRCVCW-UHFFFAOYSA-N 4-[2-(4-bicyclo[2.2.1]hept-2-enyl)ethyl]bicyclo[2.2.1]hept-2-ene Chemical compound C1CC(C2)C=CC21CCC1(C=C2)CC2CC1 YKZUNWLMLRCVCW-UHFFFAOYSA-N 0.000 description 1
- 239000005995 Aluminium silicate Substances 0.000 description 1
- MQIUGAXCHLFZKX-UHFFFAOYSA-N Di-n-octyl phthalate Natural products CCCCCCCCOC(=O)C1=CC=CC=C1C(=O)OCCCCCCCC MQIUGAXCHLFZKX-UHFFFAOYSA-N 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- CBENFWSGALASAD-UHFFFAOYSA-N Ozone Chemical compound [O-][O+]=O CBENFWSGALASAD-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 150000004996 alkyl benzenes Chemical class 0.000 description 1
- 150000005215 alkyl ethers Chemical class 0.000 description 1
- 125000005037 alkyl phenyl group Chemical group 0.000 description 1
- 150000008052 alkyl sulfonates Chemical class 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 1
- 235000012211 aluminium silicate Nutrition 0.000 description 1
- 239000003242 anti bacterial agent Substances 0.000 description 1
- 229940121375 antifungal agent Drugs 0.000 description 1
- 239000003429 antifungal agent Substances 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000003078 antioxidant effect Effects 0.000 description 1
- 229940077388 benzenesulfonate Drugs 0.000 description 1
- BJQHLKABXJIVAM-UHFFFAOYSA-N bis(2-ethylhexyl) phthalate Chemical compound CCCCC(CC)COC(=O)C1=CC=CC=C1C(=O)OCC(CC)CCCC BJQHLKABXJIVAM-UHFFFAOYSA-N 0.000 description 1
- 239000000378 calcium silicate Substances 0.000 description 1
- 229910052918 calcium silicate Inorganic materials 0.000 description 1
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical class OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 1
- 238000001035 drying Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 238000010559 graft polymerization reaction Methods 0.000 description 1
- 239000012210 heat-resistant fiber Substances 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 239000002608 ionic liquid Substances 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 230000014759 maintenance of location Effects 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000012982 microporous membrane Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- GOQYKNQRPGWPLP-UHFFFAOYSA-N n-heptadecyl alcohol Natural products CCCCCCCCCCCCCCCCCO GOQYKNQRPGWPLP-UHFFFAOYSA-N 0.000 description 1
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 239000002530 phenolic antioxidant Substances 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 238000009832 plasma treatment Methods 0.000 description 1
- 229920001083 polybutene Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 150000003242 quaternary ammonium salts Chemical class 0.000 description 1
- 229920003987 resole Polymers 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 238000006277 sulfonation reaction Methods 0.000 description 1
- 230000002195 synergetic effect Effects 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 239000006097 ultraviolet radiation absorber Substances 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
Landscapes
- Electric Double-Layer Capacitors Or The Like (AREA)
- Cell Separators (AREA)
Abstract
Description
本発明は、リチウムイオン二次電池、ポリマーリチウム二次電池、電気二重層キャパシタ、リチウムイオンキャパシタ、アルミニウム電解コンデンサ等の蓄電デバイス用セパレータおよびその製造方法に関する。 The present invention relates to a separator for an electricity storage device such as a lithium ion secondary battery, a polymer lithium secondary battery, an electric double layer capacitor, a lithium ion capacitor, and an aluminum electrolytic capacitor, and a method for producing the same.
近年、長寿命、急速充放電が可能、メンテナンスが不要などの優れた特長からコンデンサが注目されており、特に、容量が大きい電気二重層キャパシタの需要が増加している。電気二重層キャパシタは、主に各種電子機器のバックアップ電源等に使用されており、ポータブル電子機器類の小型化、高性能化に伴い、電気二重層キャパシタも小型化、高性能化が要求されている。そのため、セパレータには、厚さが薄く、高空隙率であり、かつ信頼性（耐短絡性）の高いことが要求されている。 In recent years, capacitors have attracted attention due to their excellent features such as long life, rapid charge / discharge, and no maintenance required. In particular, demand for electric double layer capacitors having a large capacity is increasing. Electric double layer capacitors are mainly used as backup power sources for various electronic devices. As portable electronic devices become smaller and higher in performance, electric double layer capacitors are also required to be smaller and higher in performance. Yes. Therefore, the separator is required to be thin, have a high porosity, and have high reliability (short circuit resistance).
有機系電解液（非水溶液系電解液）を使用した電気二重層キャパシタは、水分を嫌うため、製造工程において、高温で乾燥する必要があり、セパレータには、理想的には２００℃程度で２ｈ程度の加熱暴露に耐える耐熱性が求められる。このため、このようなセパレータには、従来から、耐熱性の繊維材料からなる不織布がよく使用されている。しかし、繊維材料からなる不織布は、安価で経済性に優れる反面、孔径が大きいため、電気二重層キャパシタの信頼性（耐短絡性）や自己放電の面で劣る欠点がある。これを改善するため、小さい孔径の得られるポリオレフィン系微多孔質フィルムにあって、耐熱性を向上させるための無機粉体を多量に含ませたポリオレフィン系微多孔質フィルムを適用することが考えられる。 An electric double layer capacitor using an organic electrolyte (non-aqueous electrolyte) dislikes moisture, and therefore needs to be dried at a high temperature in the manufacturing process. Heat resistance that can withstand the degree of heat exposure is required. For this reason, a nonwoven fabric made of a heat-resistant fiber material has been often used for such a separator. However, a non-woven fabric made of a fiber material is inexpensive and excellent in economic efficiency, but has a large pore size, and therefore has a disadvantage in terms of reliability (short-circuit resistance) and self-discharge of the electric double layer capacitor. In order to improve this, it is conceivable to apply a polyolefin microporous film containing a large amount of inorganic powder for improving heat resistance in a polyolefin microporous film having a small pore size. .
ポリオレフィン系樹脂に多量の無機粉体を含ませたポリオレフィン系微多孔質フィルムは、耐熱性が向上し、耐熱性が良好となる。しかし、この無機粉体を含ませたことによる耐熱性向上効果は、膜厚さが２００μｍ以上のポリオレフィン系微多孔質フィルムにあっては、効果が発揮されやすいものの、膜厚さが１００μｍ以下、特に５０μｍ以下になると、効果が発揮されにくくなり、耐熱性の向上に限界がある。 A polyolefin microporous film containing a large amount of inorganic powder in a polyolefin resin has improved heat resistance and good heat resistance. However, the effect of improving the heat resistance due to the inclusion of this inorganic powder is easily exerted in the polyolefin microporous film having a film thickness of 200 μm or more, but the film thickness is 100 μm or less, In particular, when the thickness is 50 μm or less, the effect is hardly exhibited, and there is a limit to improvement in heat resistance.
これを補うため、ポリオレフィン系微多孔質フィルムの耐熱性向上のための方策は、電子線照射による材料改質や、樹脂材料の変更など従来公知の方法が考えられるが、いずれも、製造設備の大幅な改良や製造工程の大幅な変更が必要であり、結果的に製造コスト（製品コスト）の増大を伴うという欠点があり、導入は容易でない。 In order to compensate for this, as a measure for improving the heat resistance of the polyolefin-based microporous film, conventionally known methods such as material modification by electron beam irradiation and resin material change can be considered. There is a drawback in that significant improvement and drastic change in the manufacturing process are required, resulting in an increase in manufacturing cost (product cost), and introduction is not easy.
そこで、本発明は、上記従来の問題点に鑑み、ポリオレフィン系樹脂に無機粉体を含ませてなる膜厚さが１００μｍ以下のポリオレフィン系微多孔質フィルムにあって、無機粉体を含ませたことによるポリオレフィン系微多孔質フィルムの耐熱性向上効果を高度に発揮させるための、補助的な耐熱性向上手法として、製造設備の大幅な改良や製造工程の大幅な変更を必要とせず、簡便かつ容易に適用でき、耐熱性が向上したポリオレフィン系微多孔質フィルム（蓄電デバイス用耐熱セパレータ）を安価に提供することを目的とする。 Therefore, in view of the above-described conventional problems, the present invention is a polyolefin microporous film having a film thickness of 100 μm or less formed by including an inorganic powder in a polyolefin resin, and including the inorganic powder. As a supplementary heat resistance improvement method to show the heat resistance improvement effect of polyolefin microporous film due to the fact that it does not require significant improvement of manufacturing equipment and manufacturing process, An object of the present invention is to provide a polyolefin microporous film (heat-resistant separator for power storage devices) that can be easily applied and has improved heat resistance at a low cost.
本発明者等は、前記目的を達成するべく鋭意検討し、次のような考え方と知見を得るに至った。
（１）ポリオレフィン系微多孔質フィルムは、小さい孔径が容易に得られることから、電気二重層キャパシタ等の蓄電デバイスの信頼性（耐短絡性）の向上や自己放電の低減の面で、従来の耐熱繊維不織布よりも優位性が高いセパレータ基材であるが、水分混入を嫌う有機系電解液（非水溶液系電解液）を使用した蓄電デバイスにおける水分除去のための加熱処理に耐える十分な耐熱性を有していない。
（２）そこで、ポリオレフィン系微多孔質フィルムの耐熱性を向上させるため、ポリオレフィン系樹脂に多量の無機粉体を含ませるようにしたポリオレフィン系微多孔質フィルムとすることが考えられる。ポリオレフィン系樹脂に多量の無機粉体を含ませたポリオレフィン系微多孔質フィルムは、耐熱性が向上し、耐熱性が良好となる。
（３）しかし、無機粉体を含ませたことによる耐熱性向上効果は、膜厚さが２００μｍ以上のポリオレフィン系微多孔質フィルムにあっては、効果が発揮されやすいものの、膜厚さが１００μｍ以下、特に５０μｍ以下になると、効果が発揮されにくくなり、耐熱性の向上に限界があることがわかった。
（４）これを補うため、ポリオレフィン系微多孔質フィルムの耐熱性向上のための方策として、従来公知の電子線照射による材料改質や樹脂材料の変更などの一般的な方法を活用することが考えられる。しかし、これらの方法は何れも、製造設備の大幅な改良や製造工程の大幅な変更が必要であり、結果的に製造コスト（製品コスト）の増大を伴うという欠点があり、導入は容易でない。
（５）よって、耐熱性向上のためポリオレフィン系樹脂に多量の無機粉体を含ませるようにした膜厚さが１００μｍ以下（５０μｍ以下）であるポリオレフィン系微多孔質フィルムにおいて、更に「微量の添加剤」を添加することによって、無機粉体を含ませたことによるポリオレフィン系微多孔質フィルムの耐熱性向上効果を効率的かつより高度に発揮させ得るような補助的な働きができる添加剤があれば面白いと考え、この考え方に基づいて添加剤を探索、検討した結果、目的に合致する有効な添加剤としてフェノール樹脂を見出した。
（６）フェノール樹脂は、ポリオレフィン系樹脂に多量の無機粉体を含ませたポリオレフィン系微多孔質フィルムの耐熱性を、従来公知の電子線照射による材料改質や樹脂材料の変更のような一般的な耐熱性向上法のように、著しく改善することはできないが、従来公知の電子線照射による材料改質や樹脂材料の変更のような一般的な耐熱性向上法のように、製造設備の大幅な改良や製造工程の大幅な変更を必要とせず、安価な材料を微量添加するという簡便、容易かつ安価な方法で、適度な耐熱性向上効果（適度な耐熱性押し上げ効果）を発揮することができる。つまり、フェノール樹脂を微量含ませるだけで、耐熱性向上のためポリオレフィン系樹脂に多量の無機粉体を含ませるようにしたポリオレフィン系樹脂微多孔質フィルムにあって、無機粉体による耐熱性向上効果が発揮されにくくなる膜厚さが１００μｍ以下（５０μｍ以下）においても、耐熱性向上効果の低下を抑え、無機粉体による耐熱性向上効果を高度に発揮できるようになること（つまり、ポリオレフィン系微多孔質フィルムの耐熱性向上策として、「多量の無機粉体の添加」と「微量のフェノール樹脂の添加」を組み合わせることで、相乗効果が発揮されて、耐熱性向上効果が高まること）を知見した。
The inventors of the present invention diligently studied to achieve the above object, and have obtained the following ideas and knowledge.
(1) Since the polyolefin-based microporous film can be easily obtained with a small pore diameter, the conventional microporous film is improved in reliability (short-circuit resistance) of an electric storage device such as an electric double layer capacitor and reduced in self-discharge. A separator base material that is superior to heat-resistant non-woven fabrics, but has sufficient heat resistance to withstand heat treatment for water removal in electricity storage devices that use organic electrolytes (non-aqueous electrolytes) that dislike mixing water Does not have.
(2) Therefore, in order to improve the heat resistance of the polyolefin microporous film, a polyolefin microporous film in which a large amount of inorganic powder is contained in the polyolefin resin can be considered. A polyolefin microporous film containing a large amount of inorganic powder in a polyolefin resin has improved heat resistance and good heat resistance.
(3) However, the effect of improving the heat resistance due to the inclusion of the inorganic powder is easily exhibited in the polyolefin microporous film having a film thickness of 200 μm or more, but the film thickness is 100 μm. In the following, it was found that, particularly when the thickness is 50 μm or less, the effect is hardly exhibited, and there is a limit to improvement in heat resistance.
(4) In order to compensate for this, as a measure for improving the heat resistance of the polyolefin-based microporous film, it is possible to utilize a general method such as a conventional material modification by electron beam irradiation or a resin material change. Conceivable. However, all of these methods require a significant improvement in manufacturing equipment and a large change in the manufacturing process. As a result, the manufacturing cost (product cost) increases, and the introduction is not easy.
(5) Therefore, in a polyolefin microporous film having a film thickness of 100 μm or less (50 μm or less) in which a large amount of inorganic powder is contained in a polyolefin resin to improve heat resistance, There is an additive that can serve as an auxiliary so that the effect of improving the heat resistance of the polyolefin microporous film due to the inclusion of the inorganic powder can be efficiently and more highly enhanced by adding `` agent ''. As a result of searching for and examining additives based on this concept, we found a phenol resin as an effective additive that meets the purpose.
(6) The phenolic resin is used for the heat resistance of a polyolefin microporous film in which a large amount of inorganic powder is contained in a polyolefin resin, such as a conventional material modification by electron beam irradiation or a resin material change. However, it cannot be improved significantly like conventional heat resistance improvement methods. However, as in the conventional heat resistance improvement methods such as material modification and resin material change by the conventional electron beam irradiation, A moderate heat resistance improvement effect (appropriate heat resistance boosting effect) can be achieved with a simple, easy and inexpensive method of adding a small amount of inexpensive material without requiring significant improvements or significant changes in the manufacturing process. Can do. In other words, a polyolefin resin microporous film in which a large amount of inorganic powder is contained in a polyolefin resin to improve heat resistance just by adding a small amount of phenolic resin. Even when the film thickness is less than 100 μm (50 μm or less), the decrease in the heat resistance improvement effect can be suppressed, and the heat resistance improvement effect by the inorganic powder can be exhibited to a high degree (that is, polyolefin fine particles). As a measure to improve the heat resistance of porous films, combining “addition of a large amount of inorganic powder” and “addition of a small amount of phenolic resin” will show a synergistic effect and increase the heat resistance improvement effect) did.
本発明の蓄電デバイス用耐熱セパレータは、このような考え方や知見に基づき、請求項１に記載の通り、重量平均分子量が５０万以上のポリオレフィン系樹脂と、比表面積が１００ｍ２／ｇ以上の無機粉体と、可塑剤とを主成分とした原料組成物を溶融混練して製膜するとともに前記可塑剤を除去することで多孔質化した、厚さが１０〜１００μｍで、平均孔径が０．０１〜０．５μｍで、空隙率が７５〜９５％である微多孔質フィルムであって、前記原料組成物に更にフェノール樹脂を含み、前記ポリオレフィン系樹脂を２０〜４０重量％、前記無機粉体を６０〜８０重量％、前記フェノール樹脂を０．２〜０．５重量％含むようにして耐熱性を向上させた微多孔質フィルムからなることを特徴とする。 Based on such a concept and knowledge, the heat-resistant separator for an electricity storage device of the present invention, as described in claim 1, is a polyolefin resin having a weight average molecular weight of 500,000 or more and an inorganic having a specific surface area of 100 m 2 / g or more. A raw material composition mainly composed of a powder and a plasticizer is melt-kneaded to form a film and the plasticizer is removed to make it porous. The thickness is 10 to 100 μm, and the average pore size is 0.1. A microporous film having a porosity of 75 to 95% at 01 to 0.5 μm, further including a phenol resin in the raw material composition, 20 to 40% by weight of the polyolefin resin, and the inorganic powder It is characterized by comprising a microporous film whose heat resistance is improved so as to contain 60 to 80% by weight and 0.2 to 0.5% by weight of the phenol resin.
また、請求項２に記載の蓄電デバイス用耐熱セパレータは、請求項１記載の蓄電デバイス用耐熱セパレータにおいて、前記厚さが５０μｍ以下であることを特徴とする。 Moreover, the heat-resistant separator for electrical storage devices according to claim 2 is the heat-resistant separator for electrical storage devices according to claim 1, wherein the thickness is 50 μm or less.
また、請求項３に記載の蓄電デバイス用耐熱セパレータは、請求項１または２記載の蓄電デバイス用耐熱セパレータにおいて、前記蓄電デバイスは有機系電解液または非水溶液系電解液を使用した蓄電デバイスであることを特徴とする。 Moreover, the heat-resistant separator for electrical storage devices according to claim 3 is the electrical storage device according to claim 1 or 2, wherein the electrical storage device uses an organic electrolytic solution or a non-aqueous electrolytic solution. It is characterized by that.
また、本発明の蓄電デバイス用耐熱セパレータの製造方法は、請求項４に記載の通り、重量平均分子量が５０万以上のポリオレフィン系樹脂と、比表面積が１００ｍ２／ｇ以上の無機粉体と、可塑剤とを主成分とした原料組成物を溶融混練して製膜するとともに前記可塑剤を除去することで多孔質化した、厚さが１０〜１００μｍで、平均孔径が０．０１〜０．５μｍで、空隙率が７５〜９５％である微多孔質フィルムであって、前記原料組成物に更にフェノール樹脂を含ませ、前記フェノール樹脂を含むようにして耐熱性を向上させた微多孔質フィルムからなる蓄電デバイス用耐熱セパレータの製造方法であって、前記原料組成物を溶融混練する工程において、前記原料組成物として、前記ポリオレフィン系樹脂を２０〜４０重量部、前記無機粉体を６０〜８０重量部および前記可塑剤を１２０〜２００重量部に対して、前記フェノール樹脂を０．２〜０．５重量部含むようにして、前記微多孔質フィルムとして、前記ポリオレフィン系樹脂を２０〜４０重量％、前記無機粉体を６０〜８０重量％、前記フェノール樹脂を０．２〜０．５重量％含むようにしたことを特徴とする。 Moreover, the manufacturing method of the heat-resistant separator for electrical storage devices of the present invention, as described in claim 4, a polyolefin resin having a weight average molecular weight of 500,000 or more, an inorganic powder having a specific surface area of 100 m 2 / g or more, A raw material composition containing a plasticizer as a main component was melt-kneaded to form a film, and the plasticizer was removed to make it porous. The thickness was 10 to 100 μm, and the average pore size was 0.01 to 0.00. It is a microporous film having a porosity of 75 to 95% at 5 μm, further comprising a phenolic resin in the raw material composition, and including the phenolic resin to improve heat resistance. In the method for producing a heat-resistant separator for an electricity storage device, in the step of melt-kneading the raw material composition, as the raw material composition, 20 to 40 parts by weight of the polyolefin resin, The polyolefin resin is used as the microporous film so as to contain 0.2 to 0.5 parts by weight of the phenol resin with respect to 60 to 80 parts by weight of the machine powder and 120 to 200 parts by weight of the plasticizer. 20 to 40% by weight, the inorganic powder 60 to 80% by weight, and the phenol resin 0.2 to 0.5% by weight.
本発明によれば、ポリオレフィン系樹脂に無機粉体を含ませてなる膜厚さが１００μｍ以下のポリオレフィン系微多孔質フィルムにあって、無機粉体を含ませたことによるポリオレフィン系微多孔質フィルムの耐熱性向上効果が高度に発揮されるようにするための補助的な耐熱性向上手法を、効果的にかつ、製造設備の大幅な改良や製造工程の大幅な変更を伴うことなく簡便かつ容易に適用できたことにより、耐熱性が向上したポリオレフィン系微多孔質フィルム（蓄電デバイス用耐熱セパレータ）を安価に提供することができる。特に、有機系電解液（非水溶液系電解液）を使用した蓄電デバイス用セパレータとして用いた場合に有用性が高い。 According to the present invention, there is a polyolefin microporous film having a film thickness of 100 μm or less formed by including an inorganic powder in a polyolefin resin, and the polyolefin microporous film obtained by including the inorganic powder. Auxiliary heat resistance improvement technique to ensure that the heat resistance improvement effect of the steel is fully demonstrated is effective and simple and easy without significant improvements in manufacturing equipment or manufacturing processes. Therefore, it is possible to provide a polyolefin microporous film (heat-resistant separator for power storage devices) with improved heat resistance at low cost. In particular, it is highly useful when used as an electrical storage device separator using an organic electrolyte (non-aqueous electrolyte).
本発明の微多孔質フィルム（微多孔膜）は、重量平均分子量が５０万以上のポリオレフィン系樹脂と、比表面積が１００ｍ２／ｇ以上の無機粉体と、可塑剤とを主成分とした原料組成物を溶融混練して製膜するとともに前記可塑剤を除去することで多孔質化した、厚さが１０〜１００μｍで、平均孔径が０．０１〜０．５μｍで、空隙率が７５〜９５％である微多孔質フィルムであって、前記原料組成物に更にフェノール樹脂を含み、前記ポリオレフィン系樹脂を２０〜４０重量％、前記無機粉体を６０〜８０重量％、前記フェノール樹脂を０．２〜０．５重量％含むようにして耐熱性を向上させたものである。 The microporous film (microporous membrane) of the present invention is a raw material mainly composed of a polyolefin resin having a weight average molecular weight of 500,000 or more, an inorganic powder having a specific surface area of 100 m 2 / g or more, and a plasticizer. The composition was melt-kneaded to form a film and porous by removing the plasticizer. The thickness was 10 to 100 μm, the average pore diameter was 0.01 to 0.5 μm, and the porosity was 75 to 95. % Of a microporous film, wherein the raw material composition further contains a phenol resin, the polyolefin resin is 20 to 40% by weight, the inorganic powder is 60 to 80% by weight, and the phenol resin is 0.1%. The heat resistance is improved by including 2 to 0.5% by weight.
微多孔質フィルムは、前述の通り、ポリオレフィン系樹脂を２０〜４０重量％含む樹脂膜でありながら、無機粉体を６０〜８０重量％含むことにより、樹脂膜にしっかりとした骨格形成がなされ、樹脂膜の補強（耐収縮性など）と耐熱補強が図られており、加熱暴露時の膜形状の維持性が高くなっている。 As described above, the microporous film is a resin film containing 20 to 40% by weight of a polyolefin-based resin, but includes 60 to 80% by weight of inorganic powder, whereby a solid skeleton is formed on the resin film. The resin film is reinforced (shrinkage resistance, etc.) and heat-resistant, and the film shape is highly maintainable when exposed to heat.
微多孔質フィルムを得るための原料組成物の主成分は、ポリオレフィン系樹脂、無機粉体、可塑剤、フェノール樹脂である。セパレータの用途、つまり、セパレータを適用する蓄電デバイスの種類によっては、電解液に対する濡れ性を確保するための界面活性剤を更に配合してもよい。通常、有機系電解液（非水溶液系電解液）を使用する蓄電デバイスに適用する場合は、有機系電解液に対して元々十分な濡れ性を有しているので界面活性剤の配合は不要であるが、水溶液系電解液を使用する蓄電デバイスに適用する場合は、界面活性剤を配合し水溶液系電解液に対する濡れ性を確保することが好ましい。尚、本願において、有機系電解液や非水溶液系電解液とは、イオン液体電解液を含むものである。 The main components of the raw material composition for obtaining the microporous film are polyolefin resin, inorganic powder, plasticizer, and phenol resin. Depending on the use of the separator, that is, the type of power storage device to which the separator is applied, a surfactant for ensuring wettability with respect to the electrolytic solution may be further blended. Normally, when applying to an electricity storage device that uses an organic electrolyte (non-aqueous electrolyte), there is no need to add a surfactant because it originally has sufficient wettability with respect to the organic electrolyte. However, when applied to an electricity storage device using an aqueous electrolyte, it is preferable to add a surfactant to ensure wettability with respect to the aqueous electrolyte. In the present application, the organic electrolytic solution and the non-aqueous electrolytic solution include an ionic liquid electrolytic solution.
本発明の微多孔質フィルムは、前述の通り、高性能化が進む蓄電デバイスに用いるセパレータにあって、厚さが薄いこと、孔径が小さいこと、空隙率が高いことの要求に適合し、厚さが１０〜１００μｍで、平均孔径が０．０１〜０．５μｍで、空隙率が７５〜９５％の微多孔質フィルムである。膜厚さが１０μｍ未満であると、セパレータとしての隔離効果を発揮しづらくなり蓄電デバイスの寿命性能に悪影響を与えるため不適である。また、膜厚さが１００μｍを超えると、セパレータの電気抵抗が高くなり蓄電デバイスの内部抵抗を高めるため不適である。よって、膜厚さは５０μｍ以下であることがより好ましい。 As described above, the microporous film of the present invention is a separator for use in an electricity storage device whose performance is increasing, and meets the requirements for a thin thickness, a small pore diameter, and a high porosity. Is a microporous film having an average pore size of 0.01 to 0.5 μm and a porosity of 75 to 95%. If the film thickness is less than 10 μm, it is difficult to exert the isolation effect as a separator, and this adversely affects the life performance of the electricity storage device. On the other hand, when the film thickness exceeds 100 μm, the electrical resistance of the separator is increased and the internal resistance of the electricity storage device is increased, which is not suitable. Therefore, the film thickness is more preferably 50 μm or less.
本発明の微多孔質フィルムを得る方法は、前述の通り、ポリオレフィン系樹脂と無機粉体と可塑剤を主体とする原料組成物を溶融混練して製膜するとともに可塑剤を除去することによる。これにより、膜全体に均一かつ微細で複雑に入り組んだ複雑な経路を有する無数の連通孔が形成された膜が得られる。具体的な製造法の一例を以下に示す。まず、ポリオレフィン系樹脂、無機粉体、可塑剤に、フェノール樹脂、必要に応じて親水化剤（界面活性剤）を加えた原材料をヘンシェルミキサーまたはレーディゲミキサー等の混合機により攪拌・混合し、原料混合物を得る。次に、この混合物を先端にＴダイを取り付けた二軸押出機に投入し加熱溶融・混練しながらシート状に押し出し、圧延・延伸等の二次加工により所定厚さのシートに成形する。次に、このシートを、適当な溶剤（例えば、ｎ−ヘキサン）中に浸漬し、可塑剤を抽出除去し乾燥、必要に応じて熱処理すれば、目的の微多孔質フィルムが得られる。尚、延伸処理は、可塑剤の抽出処理の前工程で行っても、後工程で行っても、また、前後の工程で行うようにしてもよい。 As described above, the method for obtaining the microporous film of the present invention is by melting and kneading a raw material composition mainly composed of a polyolefin resin, an inorganic powder, and a plasticizer, and removing the plasticizer. Thereby, the film | membrane in which the countless communicating hole which has the complicated path | route which was uniform, fine, and complicated was formed in the whole film | membrane is obtained. An example of a specific manufacturing method is shown below. First, a raw material obtained by adding a phenolic resin and, if necessary, a hydrophilizing agent (surfactant) to a polyolefin resin, inorganic powder, or plasticizer is agitated and mixed by a mixer such as a Henschel mixer or a Ladige mixer. To obtain a raw material mixture. Next, this mixture is put into a twin-screw extruder having a T-die attached at the tip, extruded into a sheet while heating and melting and kneading, and formed into a sheet having a predetermined thickness by secondary processing such as rolling and stretching. Next, the sheet is immersed in an appropriate solvent (for example, n-hexane), and the plasticizer is extracted and removed, dried, and heat-treated as necessary to obtain the desired microporous film. The stretching process may be performed in the preceding process of the plasticizer extraction process, in the subsequent process, or in the preceding and subsequent processes.
ポリオレフィン系樹脂としては、重量平均分子量が５０万以上であり、ポリエチレン、ポリプロピレン、ポリブテン、ポリメチルペンテン等の単独重合体または共重合体およびこれらの混合物が使用できる。中でも、成形性や経済性の面で、ポリエチレンを主体とすることが好ましい。ポリエチレンは、溶融成形温度がポリプロピレンよりも低く、生産性が良好で製造コストを抑えられる。ポリオレフィン系樹脂は、重量平均分子量が５０万以上とすることにより、無機粉体が主体の微多孔質フィルムにあって、微多孔質フィルムの機械的強度を確保することができる。そのため、ポリオレフィン系樹脂は、重量平均分子量が１００万以上であることがより好ましい。ポリオレフィン系樹脂は、無機粉体との混合性も良好で、微多孔質フィルムにあって無機粉体の骨格を接着機能材料として結合させながら強度を維持するとともに、化学的に安定であり安全性が高い。ポリオレフィン系樹脂は、更なる耐熱性を必要とする用途の場合は、ポリメチルペンテン（４−メチル−１−ペンテン）や環状ポリオレフィン（エチレン・ノルボルネン）等の高融点または高軟化点の樹脂を併用することが好ましい。 The polyolefin resin has a weight average molecular weight of 500,000 or more, and homopolymers or copolymers such as polyethylene, polypropylene, polybutene, polymethylpentene, and mixtures thereof can be used. Of these, polyethylene is the main component in terms of moldability and economy. Polyethylene has a melt molding temperature lower than that of polypropylene, has good productivity, and can suppress production costs. By setting the weight average molecular weight of the polyolefin-based resin to 500,000 or more, the microporous film mainly composed of inorganic powder can ensure the mechanical strength of the microporous film. Therefore, the polyolefin resin preferably has a weight average molecular weight of 1 million or more. Polyolefin-based resins are well mixed with inorganic powders, are in a microporous film, maintain strength while bonding the inorganic powder framework as an adhesive functional material, and are chemically stable and safe. Is expensive. For applications that require further heat resistance, polyolefin resins are used in combination with high melting point or softening point resins such as polymethylpentene (4-methyl-1-pentene) and cyclic polyolefin (ethylene norbornene). It is preferable to do.
無機粉体としては、粒径が細かく内部や表面に孔構造を備えた比表面積が１００ｍ２／ｇ以上である、シリカ、アルミナ、チタニア、珪酸カルシウム、カオリンクレー、タルク、クレー、ガラス微細粉体等の１種または２種以上が使用できる。中でも、粒子径、比表面積等の各種粉体特性の選択範囲が広く、比較的安価で入手しやすく、不純物が少ない点で、シリカが好ましい。無機粉体は、比表面積が１００ｍ２／ｇ以上であることで、微多孔質フィルムの孔径を微細化かつ複雑化して耐短絡性を高め、微多孔質フィルムの電解液保持力を高め、粉体表面に多数の親水基（−ＯＨ）を備えることにより微多孔質フィルムの親水性を高める。そのため、無機粉体の比表面積は１５０ｍ２／ｇ以上であることがより好ましい。また、無機粉体の比表面積は４００ｍ２／ｇ以下であることが好ましい。無機粉体の比表面積が４００ｍ２／ｇを超える場合は、粒子の表面活性度が高く凝集力が強くなるため、微多孔質フィルム中で無機粉体が均一分散されにくくなるため好ましくない。 As inorganic powders, silica, alumina, titania, calcium silicate, kaolin clay, talc, clay, glass fine powder with a fine particle size and a specific surface area with a pore structure inside and on the surface is 100 m 2 / g or more. 1 type or 2 types or more can be used. Among these, silica is preferable because it has a wide selection range of various powder properties such as particle diameter and specific surface area, is relatively inexpensive and easily available, and has few impurities. The inorganic powder has a specific surface area of 100 m 2 / g or more, so that the pore diameter of the microporous film is refined and complicated to improve the short circuit resistance, and the electrolyte holding power of the microporous film is increased. By providing a large number of hydrophilic groups (—OH) on the body surface, the hydrophilicity of the microporous film is enhanced. Therefore, the specific surface area of the inorganic powder is more preferably 150 m 2 / g or more. The specific surface area of the inorganic powder is preferably 400 m 2 / g or less. When the specific surface area of the inorganic powder exceeds 400 m 2 / g, the surface activity of the particles is high and the cohesive force is strong, so that it is difficult to uniformly disperse the inorganic powder in the microporous film.
フェノール樹脂としては、有機溶剤に不溶であり、ノボラックタイプまたはレゾールタイプのもの、またはエポキシ樹脂変性フェノール樹脂等が使用できる。尚、本願において、フェノール樹脂とは、特開平５−２９８９３４号公報の従来例に取り上げられるようないわゆるフェノール系酸化防止剤を含むものではない。 The phenol resin is insoluble in an organic solvent, and a novolac type or a resol type, or an epoxy resin-modified phenol resin can be used. In addition, in this application, a phenol resin does not contain what is called a phenolic antioxidant which is taken up by the prior art example of Unexamined-Japanese-Patent No. 5-298934.
可塑剤としては、ポリオレフィン系樹脂の可塑剤となり得る材料を選択することが好ましく、ポリオレフィン系樹脂と相溶性を有し各種溶剤等で容易に抽出できる各種有機液状体が使用でき、具体的には、飽和炭化水素（パラフィン）からなる工業用潤滑油等の鉱物オイル、ステアリルアルコール等の高級アルコール、フタル酸ジオクチル等のエステル系可塑剤等が使用できる。中でも、再利用がしやすい点で、鉱物オイルが好ましい。可塑剤は、原料組成物中の無機粉体１００部に対して２００〜２５０部程度を配合されることが好ましい。 As the plasticizer, it is preferable to select a material that can be a plasticizer of a polyolefin resin, and various organic liquids that are compatible with the polyolefin resin and can be easily extracted with various solvents can be used. Further, mineral oil such as industrial lubricating oil made of saturated hydrocarbon (paraffin), higher alcohol such as stearyl alcohol, ester plasticizer such as dioctyl phthalate, and the like can be used. Among these, mineral oil is preferable because it can be easily reused. The plasticizer is preferably blended in an amount of about 200 to 250 parts with respect to 100 parts of the inorganic powder in the raw material composition.
可塑剤を抽出除去するために用いる溶剤（溶媒）としては、ヘキサン、ヘプタン、オクタン、ノナン、デカン等の飽和炭化水素系の有機溶剤を使用することができる。 As a solvent (solvent) used for extracting and removing the plasticizer, a saturated hydrocarbon organic solvent such as hexane, heptane, octane, nonane and decane can be used.
本発明の微多孔質フィルムは、親水性の無機粉体を多量に含有しており、親水性を有するが、セパレータの用途に応じて、水溶液系電解液を使用する蓄電デバイスに適用する場合は、更に親水性を高めるための親水性付与手段を講じるようにしても良い。親水性付与手段としては、界面活性剤を処理あるいは添加する方法、水溶性モノマーをグラフト重合する方法、スルホン化処理、プラズマ処理、オゾン処理等の中から自由に選択できる。中でも、界面活性剤を処理あるいは添加する方法が比較的簡易であり好ましい。 When the microporous film of the present invention contains a large amount of hydrophilic inorganic powder and has hydrophilicity, depending on the use of the separator, when applied to an electricity storage device using an aqueous electrolyte solution Further, a hydrophilicity imparting means for further enhancing the hydrophilicity may be provided. The hydrophilicity imparting means can be freely selected from a method of treating or adding a surfactant, a method of graft polymerization of a water-soluble monomer, a sulfonation treatment, a plasma treatment, an ozone treatment and the like. Among these, a method of treating or adding a surfactant is relatively simple and preferable.
界面活性剤を処理あるいは添加する方法としては、溶融製膜前の原料組成物中に予め分散状態に添加しておく方法（内添法）、溶融製膜された微多孔質フィルムに対して後処理する方法（外添法）があるが、製造工程が簡略化できる点と、本発明の微多孔質フィルムから界面活性剤を染み出しにくくできる点で、原料組成物中に予め添加する方法（内添法）が好ましい。 As a method for treating or adding the surfactant, a method in which the surfactant is added in a dispersed state in the raw material composition before melt film formation (internal addition method), or a microporous film formed by melt film formation is added later. There is a method of processing (external addition method), but a method of adding in advance to the raw material composition in that the production process can be simplified and the surfactant can be hardly exuded from the microporous film of the present invention ( The internal addition method) is preferred.
界面活性剤としては、ポリオレフィン系樹脂の親水性を向上できる材料であればよく、ノニオン系界面活性剤、カチオン系界面活性剤、アニオン系界面活性剤の何れも使用できる。ノニオン系界面活性剤としては、ポリオキシエチレンアルキルエーテル類、ポリオキシエチレンアルキルフェニルエーテル類、ポリオキシエチレンアルキルアリルエーテル類、脂肪酸モノグリセリド、ソルビタン脂肪酸エステル類等が使用できる。カチオン系界面活性剤としては、脂肪族アミン塩類、第四級アンモニウム塩、ポリオキシエチレンアルキルアミン、アルキルアミンオキシド等が使用できる。アニオン系界面活性剤としては、アルキルスルフォン酸塩、アルキルベンゼンスルフォン酸塩、アルキルナフタレンスルフォン酸塩、アルキルスルホコハク酸塩等が使用できる。中でも、ポリオレフィン系樹脂に対して、少量の添加で、高い親水性の付与が可能であることから、アルキルスルホコハク酸塩が好ましい。 The surfactant may be any material that can improve the hydrophilicity of the polyolefin-based resin, and any of nonionic surfactants, cationic surfactants, and anionic surfactants can be used. As the nonionic surfactant, polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenyl ethers, polyoxyethylene alkyl allyl ethers, fatty acid monoglycerides, sorbitan fatty acid esters and the like can be used. As the cationic surfactant, aliphatic amine salts, quaternary ammonium salts, polyoxyethylene alkylamines, alkylamine oxides and the like can be used. As the anionic surfactant, alkyl sulfonate, alkyl benzene sulfonate, alkyl naphthalene sulfonate, alkyl sulfosuccinate and the like can be used. Among these, alkylsulfosuccinate is preferable because high hydrophilicity can be imparted to the polyolefin-based resin with a small amount of addition.
原料組成物または微多孔質フィルムには、その他、必要に応じて、酸化防止剤、紫外線吸収剤、耐候剤、滑剤、抗菌剤、防黴剤、顔料、染料、着色剤、防曇剤、艶消し剤等の添加剤を、本発明の目的および効果を損なわない範囲で添加（配合）または含有させてもよい。 In addition to the raw material composition or microporous film, an antioxidant, an ultraviolet absorber, a weathering agent, a lubricant, an antibacterial agent, an antifungal agent, a pigment, a dye, a colorant, an antifogging agent, a glossy agent are optionally added. Additives such as an eraser may be added (blended) or contained within a range that does not impair the object and effect of the present invention.
本発明の微多孔質フィルムは、前述の通り、ポリオレフィン系樹脂を２０〜４０重量％と、無機粉体を６０〜８０重量％と、フェノール樹脂を０．２〜０．５重量％含む。ポリオレフィン系樹脂の含有量が２０重量％未満であると、ポリオレフィン系樹脂を微多孔質フィルム全体に均一に分散できなくなり、微多孔質フィルムの十分な機械的強度を確保できなくなるため不適である。無機粉体の含有量が８０重量％を超える場合も、ポリオレフィン系樹脂の含有量が２０重量％未満となるため、同様の理由により不適である。また、無機粉体の含有量が６０重量％未満であると、微多孔質フィルムの耐熱性向上効果、微多孔質フィルムの孔構造を微細化かつ複雑化し短絡を防止する効果、微多孔質フィルムの電解液を保持する効果等が十分に発揮できなくなるため不適である。また、無機粉体の含有量が６０重量％未満であると、可塑剤の配合量が減少するため、微多孔質フィルムの密度が上昇し、空隙率が低下し、蓄電デバイスの内部抵抗を高めるため不適である。ポリオレフィン系樹脂の含有量が４０重量％を超える場合も、無機粉体の含有量が６０重量％未満となるため、同様の理由により不適である。尚、本発明の微多孔質フィルムは、前述の通り、ポリオレフィン系樹脂と無機粉体と可塑剤を主体とする原料組成物を溶融混練して製膜するとともに可塑剤を除去することによって得られるが、原料組成物中のポリオレフィン系樹脂と無機粉体の構成比率と、微多孔質フィルム中のポリオレフィン系樹脂と無機粉体の構成比率は、基本的に変わらない。また、フェノール樹脂は、微多孔質フィルム中に０．２重量％以上含ませることにより、無機粉体を含ませたことによるポリオレフィン系微多孔質フィルムの耐熱性向上効果を補助し同効果を高度に発揮させる効果を有するが、０．５重量％を超えて含ませても、その効果は向上しない。また、フェノール樹脂を０．５重量％を超えて多く含ませると、高温時のポリオレフィン系樹脂の粘度を低下させるため、溶融混練押出時の樹脂圧力が低くなり、溶融混練押出時に原料組成物が均一に分散せず、製膜された膜の欠陥数が多くなるため不適である。 As described above, the microporous film of the present invention contains 20 to 40% by weight of polyolefin resin, 60 to 80% by weight of inorganic powder, and 0.2 to 0.5% by weight of phenol resin. If the content of the polyolefin resin is less than 20% by weight, the polyolefin resin cannot be uniformly dispersed throughout the microporous film, and it is not suitable because sufficient mechanical strength of the microporous film cannot be ensured. Even when the content of the inorganic powder exceeds 80% by weight, the content of the polyolefin resin is less than 20% by weight, which is not suitable for the same reason. Further, when the content of the inorganic powder is less than 60% by weight, the heat resistance improvement effect of the microporous film, the effect of miniaturizing and complicating the pore structure of the microporous film and preventing short circuit, the microporous film This is not suitable because the effect of retaining the electrolyte cannot be sufficiently exhibited. Further, when the content of the inorganic powder is less than 60% by weight, the amount of the plasticizer decreases, so the density of the microporous film increases, the porosity decreases, and the internal resistance of the electricity storage device increases. Therefore, it is unsuitable. Even when the content of the polyolefin resin exceeds 40% by weight, the content of the inorganic powder is less than 60% by weight, which is not suitable for the same reason. As described above, the microporous film of the present invention is obtained by melt-kneading a raw material composition mainly composed of a polyolefin resin, an inorganic powder, and a plasticizer to form a film and removing the plasticizer. However, the composition ratio between the polyolefin resin and the inorganic powder in the raw material composition and the composition ratio between the polyolefin resin and the inorganic powder in the microporous film are basically the same. In addition, by adding 0.2% by weight or more of the phenol resin in the microporous film, the effect of improving the heat resistance of the polyolefin microporous film due to the inclusion of the inorganic powder is enhanced. However, even if the content exceeds 0.5% by weight, the effect is not improved. Further, when the phenol resin is contained in a large amount exceeding 0.5% by weight, the viscosity of the polyolefin resin at high temperature is lowered, so that the resin pressure at the time of melt kneading extrusion is lowered, and the raw material composition is at the time of melt kneading extrusion. It is not suitable because it is not uniformly dispersed and the number of defects in the formed film increases.
次に、本発明の実施例について比較例と共に詳細に説明する。
（実施例１）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部（重量部、以下同じ）と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、ノボラックタイプフェノール樹脂粉体０．７部、無機粉体として比表面積１５０ｍ２／ｇのシリカ粉体１９０部、可塑剤として鉱物オイルの一種であるパラフィン系オイル４１０部をレーディゲミキサーで混合し、先端にＴダイを取り付けた二軸押出成形機で加熱溶融・混練しながらシート状に押出成形し、次いで成形ロールにて圧延処理して厚さ１３０μｍのシートを得た。次に、このシートを一軸方向に延伸処理した後、前記可塑剤を有機溶剤で抽出除去し、加熱乾燥して、ポリエチレン樹脂３４．４重量％、フェノール樹脂０．２重量％、シリカ粉体６５．４重量％で構成される厚さ４１μｍの微多孔質フィルムからなる蓄電デバイス用セパレータを得た。得られたセパレータの耐熱性を測定した結果、雰囲気温度２００℃、保持時間１２０分の条件で形状保持し、目標を満足した。
Next, examples of the present invention will be described in detail together with comparative examples.
Example 1
70 parts (parts by weight, the same shall apply hereinafter) of high density polyethylene resin powder having a weight average molecular weight of 2 million as polyolefin resin, 30 parts of high density polyethylene resin powder having a weight average molecular weight of 200,000, and 0. 7 parts, 190 parts of silica powder having a specific surface area of 150 m 2 / g as inorganic powder, and 410 parts of paraffinic oil, which is a kind of mineral oil, as a plasticizer were mixed with a Ladige mixer, and a T-die was attached to the tip. The sheet was extruded into a sheet while being heated and melted and kneaded with a biaxial extruder, and then rolled with a forming roll to obtain a sheet having a thickness of 130 μm. Next, the sheet was stretched in a uniaxial direction, and then the plasticizer was extracted and removed with an organic solvent, followed by heating and drying to obtain 34.4% by weight of a polyethylene resin, 0.2% by weight of a phenol resin, and 65% of silica powder. The separator for electrical storage devices which consists of a 41-micrometer-thick microporous film comprised by 4 weight% was obtained. As a result of measuring the heat resistance of the obtained separator, the shape was held under the conditions of an atmospheric temperature of 200 ° C. and a holding time of 120 minutes, and the target was satisfied.
（実施例２）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、ノボラックタイプフェノール樹脂粉体１．４部、無機粉体として比表面積１５０ｍ２／ｇのシリカ粉体１９０部、可塑剤として鉱物オイルの一種であるパラフィン系オイル４１０部をレーディゲミキサーで混合し、実施例１と同様にして、ポリエチレン樹脂３４．３重量％、フェノール樹脂０．５重量％、シリカ粉体６５．２重量％で構成される厚さ４０μｍの微多孔質フィルムからなる蓄電デバイス用セパレータを得た。得られたセパレータの耐熱性を測定した結果、雰囲気温度２００℃、保持時間１２０分の条件で形状保持し、目標を満足した。
(Example 2)
As a polyolefin resin, 70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, 1.4 parts of a novolac type phenol resin powder, and an inorganic powder 190 parts of silica powder having a specific surface area of 150 m 2 / g and 410 parts of paraffinic oil, which is a kind of mineral oil, are mixed as a plasticizer with a Ladige mixer. In the same manner as in Example 1, 34.3 wt. %, A phenol resin 0.5% by weight and a silica powder 65.2% by weight, a 40 μm-thick microporous film composed of a microporous film was obtained. As a result of measuring the heat resistance of the obtained separator, the shape was held under the conditions of an atmospheric temperature of 200 ° C. and a holding time of 120 minutes, and the target was satisfied.
（実施例３）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、ノボラックタイプフェノール樹脂粉体１．４部、無機粉体として比表面積１５０ｍ２／ｇのシリカ粉体１９０部、可塑剤として鉱物オイルの一種であるパラフィン系オイル４１０部をレーディゲミキサーで混合し、先端にＴダイを取り付けた二軸押出成形機で加熱溶融・混練しながらシート状に押出成形し、次いで成形ロールにて圧延処理して厚さ８０μｍのシートを得た。次に、このシートを一軸方向に延伸処理した後、前記可塑剤を有機溶剤で抽出除去し、ポリエチレン樹脂３４．３重量％、フェノール樹脂０．５重量％、シリカ粉体６５．２重量％で構成される厚さ１８μｍの微多孔質フィルムからなる蓄電デバイス用セパレータを得た。得られたセパレータの耐熱性を測定した結果、雰囲気温度２００℃、保持時間１２０分の条件で形状保持し、目標を満足した。
(Example 3)
As a polyolefin resin, 70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, 1.4 parts of a novolac type phenol resin powder, and an inorganic powder 190 parts of silica powder with a specific surface area of 150 m 2 / g and 410 parts of paraffinic oil, which is a kind of mineral oil as a plasticizer, are mixed with a Ladige mixer and heated with a twin-screw extruder with a T die attached to the tip. It was extruded into a sheet while melting and kneading, and then rolled with a forming roll to obtain a sheet having a thickness of 80 μm. Next, the sheet was stretched in a uniaxial direction, and the plasticizer was extracted and removed with an organic solvent. The polyethylene resin was 34.3% by weight, the phenol resin was 0.5% by weight, and the silica powder was 65.2% by weight. An electricity storage device separator made of a microporous film having a thickness of 18 μm was obtained. As a result of measuring the heat resistance of the obtained separator, the shape was held under the conditions of an atmospheric temperature of 200 ° C. and a holding time of 120 minutes, and the target was satisfied.
（実施例４）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、ノボラックタイプフェノール樹脂粉体１．４部、無機粉体として比表面積１５０ｍ２／ｇのシリカ粉体１９０部、可塑剤として鉱物オイルの一種であるパラフィン系オイル４１０部をレーディゲミキサーで混合し、先端にＴダイを取り付けた二軸押出成形機で加熱溶融・混練しながらシート状に押出成形し、次いで成形ロールにて圧延処理して厚さ９２μｍのシートを得た。このシートを延伸処理を行わずに、前記可塑剤を有機溶剤で抽出除去し、ポリエチレン樹脂３４．３重量％、フェノール樹脂０．５重量％、シリカ粉体６５．２重量％で構成される厚さ９２μｍの微多孔質フィルムからなる蓄電デバイス用セパレータを得た。得られたセパレータの耐熱性を測定した結果、雰囲気温度２００℃、保持時間１２０分の条件で形状保持し、目標を満足した。
Example 4
As a polyolefin resin, 70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, 1.4 parts of a novolac type phenol resin powder, and an inorganic powder 190 parts of silica powder with a specific surface area of 150 m 2 / g and 410 parts of paraffinic oil, which is a kind of mineral oil as a plasticizer, are mixed with a Ladige mixer and heated with a twin-screw extruder with a T die attached to the tip. It was extruded into a sheet while melting and kneading, and then rolled with a forming roll to obtain a sheet having a thickness of 92 μm. The sheet was not subjected to stretching treatment, and the plasticizer was extracted and removed with an organic solvent. The thickness was composed of 34.3 wt% polyethylene resin, 0.5 wt% phenol resin, and 65.2 wt% silica powder. A separator for an electricity storage device made of a microporous film having a thickness of 92 μm was obtained. As a result of measuring the heat resistance of the obtained separator, the shape was held under the conditions of an atmospheric temperature of 200 ° C. and a holding time of 120 minutes, and the target was satisfied.
（比較例１）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、無機粉体として比表面積１５０ｍ２／ｇのシリカ粉体１９０部、可塑剤として鉱物オイルの一種であるパラフィン系オイル４１０部をレーディゲミキサーで混合し、実施例１と同様にして、ポリエチレン樹脂３４．５重量％とシリカ粉体６５．５重量％で構成される厚さ３９μｍの微多孔質フィルムからなる蓄電デバイス用セパレータを得た。得られたセパレータの耐熱性を測定した結果、雰囲気温度２００℃、保持時間１２０分の条件で形状保持できなかった。
(Comparative Example 1)
70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million as a polyolefin resin, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, and silica powder 190 having a specific surface area of 150 m 2 / g as an inorganic powder. Part, paraffinic oil 410 parts, which is a kind of mineral oil as a plasticizer, was mixed with a Laedige mixer, and in the same manner as in Example 1, 34.5% by weight of polyethylene resin and 65.5% by weight of silica powder. An electricity storage device separator made of a 39 μm-thick microporous film was obtained. As a result of measuring the heat resistance of the obtained separator, the shape could not be retained under the conditions of an atmospheric temperature of 200 ° C. and a retention time of 120 minutes.
（比較例２）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、ノボラックタイプフェノール樹脂粉体２．８部、無機粉体として比表面積１５０ｍ２／ｇのシリカ粉体１９０部、可塑剤として鉱物オイルの一種であるパラフィン系オイル４１０部をレーディゲミキサーで混合し、実施例１と同様にして、ポリエチレン樹脂３４．２重量％、フェノール樹脂１．０重量％、シリカ粉体６４．９重量％で構成される厚さ４１μｍの微多孔質フィルムからなる蓄電デバイス用セパレータを得た。しかし、溶融混練押出時に、樹脂圧力が低下し、原料組成物が均一に分散せず混練不足の状態で製膜が行われたことにより、その後の延伸処理にてシート破断がしばしば発生する状況であった。得られたセパレータの耐熱性は、雰囲気温度２００℃、保持時間１２０分の条件で形状保持し、目標を満足した。
(Comparative Example 2)
As a polyolefin resin, 70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, 2.8 parts of a novolac type phenol resin powder, 190 parts of silica powder having a specific surface area of 150 m 2 / g and 410 parts of paraffinic oil, which is a kind of mineral oil, are mixed as a plasticizer using a Ladige mixer. In the same manner as in Example 1, 34.2 wt. %, A phenol resin 1.0 wt%, and a silica powder 64.9 wt%, a 41 μm thick microporous film was obtained. However, during melt-kneading extrusion, the resin pressure decreases, the raw material composition is not uniformly dispersed, and film formation is performed in a state where kneading is insufficient, so that sheet breakage often occurs in subsequent stretching treatments. there were. As for the heat resistance of the obtained separator, the shape was maintained under the conditions of an atmospheric temperature of 200 ° C. and a holding time of 120 minutes, and the target was satisfied.
（比較例３）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、ノボラックタイプフェノール樹脂粉体０．７部、無機粉体として比表面積１５０ｍ２／ｇのシリカ粉体１４０部、可塑剤として鉱物オイルの一種であるパラフィン系オイル３０２部をレーディゲミキサーで混合し、実施例１と同様にして、ポリエチレン樹脂４１．５重量％、フェノール樹脂０．３重量％、シリカ粉体５８．２重量％で構成される厚さ４０μｍの微多孔質フィルムからなる蓄電デバイス用セパレータを得た。得られたセパレータの耐熱性を測定した結果、雰囲気温度２００℃、保持時間１２０分の条件で形状保持し、目標を満足した。しかし、得られたセパレータの密度が高く、空隙率が低下し、蓄電デバイスの内部抵抗が上昇する問題が発生した。
(Comparative Example 3)
As polyolefin resin, 70 parts of high density polyethylene resin powder with a weight average molecular weight of 2 million, 30 parts of high density polyethylene resin powder with a weight average molecular weight of 200,000, 0.7 parts of novolac type phenol resin powder, as inorganic powder 140 parts of silica powder having a specific surface area of 150 m 2 / g and 302 parts of paraffinic oil, which is a kind of mineral oil, are mixed as a plasticizer using a Ladige mixer. %, A phenol resin 0.3% by weight, and a silica powder 58.2% by weight, a 40 μm thick microporous film was obtained. As a result of measuring the heat resistance of the obtained separator, the shape was held under the conditions of an atmospheric temperature of 200 ° C. and a holding time of 120 minutes, and the target was satisfied. However, the density of the obtained separator is high, the porosity is lowered, and the internal resistance of the electricity storage device is increased.
（比較例４）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、ノボラックタイプフェノール樹脂粉体１．４部、無機粉体として比表面積１５０ｍ２／ｇのシリカ粉体４１０部、可塑剤として鉱物オイルの一種であるパラフィン系オイル８８５部をレーディゲミキサーで混合し、実施例１と同様にして、ポリエチレン樹脂１９．６重量％、フェノール樹脂０．３重量％、シリカ粉体８０．２重量％で構成される厚さ４１μｍの微多孔質フィルムからなる蓄電デバイス用セパレータを得た。しかし、溶融混練押出時に、樹脂圧力が低下し、原料組成物が均一に分散せず混練不足の状態で製膜が行われたことにより、その後の延伸処理にてシート破断がしばしば発生する状況であった。得られたセパレータの耐熱性を測定した結果、雰囲気温度２００℃、保持時間１２０分の条件で形状保持し、目標を満足した。しかし、得られたセパレータの強度が低く、蓄電デバイスの組み立てにおいて、セパレータが破断する問題が発生した。
(Comparative Example 4)
As a polyolefin resin, 70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, 1.4 parts of a novolac type phenol resin powder, and an inorganic powder 410 parts of silica powder having a specific surface area of 150 m 2 / g and 885 parts of paraffinic oil which is a kind of mineral oil as a plasticizer were mixed with a Ladige mixer, and in the same manner as in Example 1, 19.6 wt. %, A phenol resin 0.3% by weight, silica powder 80.2% by weight, a 41 μm-thick microporous film was obtained. However, during melt-kneading extrusion, the resin pressure decreases, the raw material composition is not uniformly dispersed, and film formation is performed in a state where kneading is insufficient, so that sheet breakage often occurs in subsequent stretching treatments. there were. As a result of measuring the heat resistance of the obtained separator, the shape was held under the conditions of an atmospheric temperature of 200 ° C. and a holding time of 120 minutes, and the target was satisfied. However, the strength of the obtained separator is low, and there has been a problem that the separator breaks during assembly of the electricity storage device.
次に、上記にて得られた実施例１〜４、比較例１〜４の各セパレータについて、以下の方法により、各種特性評価を行った。結果を表１に示す。尚、以下において、幅方向とは、原反の帯状シートの流れ方向（長手方向）に対して直交する方向を指す。
〈厚さ〉
０．００１ｍｍ目盛のダイヤルシックネスゲージにより測定し、幅方向に５箇所測定し、その平均を値とした。
〈密度〉
測定した目付（ｇ／ｍ２）を試料厚さ（μｍ）で除した計算値（目付÷厚さ）で算出した。
〈空隙率〉
平均孔径を測定する方法の一つである水銀圧入法で、試料への水銀の圧入量より空隙率を求めた。
〈平均孔径〉
水銀圧入法（ＪＩＳ Ｒ １６５５）により測定し、平均孔径を求めた。
〈引張強さ〉
ＪＩＳ Ｋ ７１１３に準拠した方法で、チャック間距離５０ｍｍ、引張速度２００ｍｍ／分の条件で、幅方向から３箇所サンプリング測定し、その平均を値とした。
〈突き刺し強度〉
試験片上部よりφ１ｍｍの鉄棒を速度１００ｍｍ／分の条件で突き刺し、試験片が破断した最大荷重を測定した。
〈耐熱性〉
箱型乾燥機にて、雰囲気温度２００℃で１２０分間、暴露させてから取り出し、形状を保持したものを○、炭化したものを×として評価した。
Next, various characteristics evaluation was performed by the following method about each separator of Examples 1-4 obtained by the above, and Comparative Examples 1-4. The results are shown in Table 1. In the following, the width direction refers to a direction orthogonal to the flow direction (longitudinal direction) of the original strip-shaped sheet.
<thickness>
Measurement was made with a dial thickness gauge having a 0.001 mm scale, and five points were measured in the width direction.
<density>
The measured basis weight (g / m 2 ) was calculated by dividing the sample thickness (μm) by a calculated value (weight per unit area / thickness).
<Porosity>
The porosity was determined from the amount of mercury injected into the sample by the mercury intrusion method, which is one of the methods for measuring the average pore diameter.
<Average pore diameter>
It measured by the mercury intrusion method (JISR1655) and calculated | required the average hole diameter.
<Tensile strength>
Using a method in accordance with JIS K 7113, three points were sampled from the width direction under conditions of a distance between chucks of 50 mm and a tensile speed of 200 mm / min, and the average was taken as a value.
<Puncture strength>
An iron bar with a diameter of 1 mm was pierced from the upper part of the test piece at a speed of 100 mm / min, and the maximum load at which the test piece broke was measured.
<Heat-resistant>
Using a box-type dryer, the film was exposed for 120 minutes at an atmospheric temperature of 200 ° C. and then taken out.
表１の結果から以下のことがわかった。
（１）本発明の実施例１〜４の微多孔質フィルム（蓄電デバイス用セパレータ）は、溶融混練押出時の樹脂圧力が８０％（比較例１の樹脂圧力を１００％として）以上を確保し、溶融混練押出時の原料組成物の均一分散性の低下による製膜シートの欠陥を抑え、また、空隙率が７５％以上を確保し、蓄電デバイスの内部抵抗の上昇を抑え、また、引張強さが３０Ｎ／ｍｍ２以上を確保しながら、耐熱性が良好であった（２００℃で１２０分間暴露後に炭化せず形状を保持した）。
（２）これに対し、比較例１の微多孔質フィルム（蓄電デバイス用セパレータ）は、フェノール樹脂を含ませなかったため、耐熱性が良好ではなかった（２００℃で１２０分間暴露後に炭化し形状を保持できなかった）。また、比較例２の微多孔質フィルム（蓄電デバイス用セパレータ）は、フェノール樹脂を１．０重量％含ませたため、耐熱性は良好であった（２００℃で１２０分間暴露後に炭化せず形状を保持した）が、溶融混練押出時の樹脂圧力が８０％（比較例１の樹脂圧力を１００％として）未満に低下し、溶融混練押出時の原料組成物の均一分散性の低下による製膜シートの欠陥が多発した。また、比較例３の微多孔質フィルム（蓄電デバイス用セパレータ）は、無機粉体の含有量が６０重量％未満であったため、空隙率が７５％未満に低下し、蓄電デバイスの内部抵抗の上昇が顕著であった。また、比較例４の微多孔質フィルム（蓄電デバイス用セパレータ）は、ポリオレフィン系樹脂の含有量が２０重量％未満であったため、引張強さが３０Ｎ／ｍｍ２未満に低下し、十分な機械的強度を確保できなかった。
From the results in Table 1, the following was found.
(1) The microporous films (electrical storage device separators) of Examples 1 to 4 of the present invention ensure that the resin pressure during melt-kneading extrusion is 80% or more (with the resin pressure of Comparative Example 1 being 100%) or more. , Suppressing defects in the film-forming sheet due to a decrease in the uniform dispersibility of the raw material composition during melt-kneading extrusion, ensuring a porosity of 75% or more, suppressing an increase in internal resistance of the electricity storage device, and tensile strength The heat resistance was good while securing a thickness of 30 N / mm 2 or more (the shape was maintained without being carbonized after exposure at 200 ° C. for 120 minutes).
(2) On the other hand, since the microporous film (electric storage device separator) of Comparative Example 1 did not contain a phenol resin, the heat resistance was not good (carbonized after exposure at 200 ° C. for 120 minutes). Couldn't hold). Moreover, since the microporous film (electrical storage device separator) of Comparative Example 2 contained 1.0% by weight of phenol resin, the heat resistance was good (the shape was not carbonized after exposure for 120 minutes at 200 ° C.). However, the resin pressure at the time of melt-kneading extrusion is reduced to less than 80% (assuming the resin pressure of Comparative Example 1 is 100%), and the film-forming sheet is caused by a decrease in the uniform dispersibility of the raw material composition at the time of melt-kneading extrusion. Frequent defects occurred. Moreover, since the content of the inorganic powder was less than 60% by weight in the microporous film of Comparative Example 3 (electric storage device separator), the porosity decreased to less than 75%, and the internal resistance of the electricity storage device increased. Was remarkable. Moreover, since the content of polyolefin resin was less than 20% by weight in the microporous film of Comparative Example 4 (electric storage device separator), the tensile strength was reduced to less than 30 N / mm 2 , and sufficient mechanical properties were obtained. The strength could not be secured.
Claims (4)
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015140439A (en) * | 2015-04-24 | 2015-08-03 | 住友化学株式会社 | Coat solution and layered porous film |
| WO2019107119A1 (en) * | 2017-11-28 | 2019-06-06 | 旭化成株式会社 | Separator for power storage device and method for producing same, and power storage device and method for producing same |
| WO2020151357A1 (en) * | 2019-01-25 | 2020-07-30 | 深圳锂硫科技有限公司 | Lithium battery separator and preparation method therefor |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07130348A (en) * | 1993-11-04 | 1995-05-19 | Nippon Muki Co Ltd | Separator for storage battery |
| JP2006287175A (en) * | 2005-03-09 | 2006-10-19 | Nippon Sheet Glass Co Ltd | Separator for electricity storage device, its production process and electricity storage device |
| JP2007095440A (en) * | 2005-09-28 | 2007-04-12 | Nippon Sheet Glass Co Ltd | Separator for electric storage device, and electric storage device |
-
2011
- 2011-09-26 JP JP2011209358A patent/JP2013070006A/en not_active Ceased
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH07130348A (en) * | 1993-11-04 | 1995-05-19 | Nippon Muki Co Ltd | Separator for storage battery |
| JP2006287175A (en) * | 2005-03-09 | 2006-10-19 | Nippon Sheet Glass Co Ltd | Separator for electricity storage device, its production process and electricity storage device |
| JP2007095440A (en) * | 2005-09-28 | 2007-04-12 | Nippon Sheet Glass Co Ltd | Separator for electric storage device, and electric storage device |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2015140439A (en) * | 2015-04-24 | 2015-08-03 | 住友化学株式会社 | Coat solution and layered porous film |
| WO2019107119A1 (en) * | 2017-11-28 | 2019-06-06 | 旭化成株式会社 | Separator for power storage device and method for producing same, and power storage device and method for producing same |
| US11804617B2 (en) | 2017-11-28 | 2023-10-31 | Asahi Kasei Kabushiki Kaisha | Separator for power storage device and method for producing same, and power storage device and method for producing same |
| WO2020151357A1 (en) * | 2019-01-25 | 2020-07-30 | 深圳锂硫科技有限公司 | Lithium battery separator and preparation method therefor |
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