JP2014179519A - Separator for electricity storage device, and electricity storage device - Google Patents
Separator for electricity storage device, and electricity storage device Download PDFInfo
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- 238000003860 storage Methods 0.000 title claims abstract description 49
- 230000005611 electricity Effects 0.000 title claims abstract description 45
- 239000000843 powder Substances 0.000 claims abstract description 133
- 229920005672 polyolefin resin Polymers 0.000 claims abstract description 89
- 239000004094 surface-active agent Substances 0.000 claims abstract description 86
- 239000003792 electrolyte Substances 0.000 claims abstract description 69
- 239000004014 plasticizer Substances 0.000 claims abstract description 67
- 239000000203 mixture Substances 0.000 claims abstract description 62
- 239000011148 porous material Substances 0.000 claims abstract description 57
- 239000002994 raw material Substances 0.000 claims abstract description 56
- 239000002608 ionic liquid Substances 0.000 claims abstract description 46
- 150000003839 salts Chemical class 0.000 claims abstract description 18
- 238000000465 moulding Methods 0.000 claims abstract description 14
- 238000005096 rolling process Methods 0.000 claims abstract description 12
- 239000007787 solid Substances 0.000 claims abstract description 9
- 239000008151 electrolyte solution Substances 0.000 claims description 38
- 238000012835 hanging drop method Methods 0.000 claims description 9
- 239000000463 material Substances 0.000 abstract description 35
- 238000002844 melting Methods 0.000 abstract description 12
- 230000008018 melting Effects 0.000 abstract description 12
- 238000002156 mixing Methods 0.000 abstract description 9
- 239000010408 film Substances 0.000 description 135
- 238000000034 method Methods 0.000 description 59
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 52
- 239000000758 substrate Substances 0.000 description 29
- 239000003990 capacitor Substances 0.000 description 28
- 239000000377 silicon dioxide Substances 0.000 description 26
- 230000001965 increasing effect Effects 0.000 description 25
- 230000000052 comparative effect Effects 0.000 description 24
- -1 nickel metal hydride Chemical class 0.000 description 20
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- 238000012360 testing method Methods 0.000 description 19
- 239000003795 chemical substances by application Substances 0.000 description 15
- 238000004898 kneading Methods 0.000 description 14
- 230000000694 effects Effects 0.000 description 13
- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 13
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 12
- 239000007788 liquid Substances 0.000 description 11
- 230000014759 maintenance of location Effects 0.000 description 11
- 239000011265 semifinished product Substances 0.000 description 11
- 239000002904 solvent Substances 0.000 description 11
- 125000001165 hydrophobic group Chemical group 0.000 description 10
- 239000010690 paraffinic oil Substances 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 239000002585 base Substances 0.000 description 9
- 239000011163 secondary particle Substances 0.000 description 9
- 239000002253 acid Substances 0.000 description 8
- 125000000217 alkyl group Chemical group 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 7
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- 239000011347 resin Substances 0.000 description 7
- 208000028659 discharge Diseases 0.000 description 6
- 238000000605 extraction Methods 0.000 description 6
- 239000002480 mineral oil Substances 0.000 description 6
- 235000010446 mineral oil Nutrition 0.000 description 6
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 5
- 239000003963 antioxidant agent Substances 0.000 description 5
- 230000003247 decreasing effect Effects 0.000 description 5
- 238000010438 heat treatment Methods 0.000 description 5
- 239000005011 phenolic resin Substances 0.000 description 5
- 229920003171 Poly (ethylene oxide) Polymers 0.000 description 4
- 229910001416 lithium ion Inorganic materials 0.000 description 4
- GLDOVTGHNKAZLK-UHFFFAOYSA-N octadecan-1-ol Chemical compound CCCCCCCCCCCCCCCCCCO GLDOVTGHNKAZLK-UHFFFAOYSA-N 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- 229920000098 polyolefin Polymers 0.000 description 4
- 239000002356 single layer Substances 0.000 description 4
- 159000000000 sodium salts Chemical class 0.000 description 4
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- 239000004698 Polyethylene Substances 0.000 description 3
- 239000000654 additive Substances 0.000 description 3
- 230000003078 antioxidant effect Effects 0.000 description 3
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- 238000001125 extrusion Methods 0.000 description 3
- 238000005259 measurement Methods 0.000 description 3
- 239000000155 melt Substances 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
- 229910052987 metal hydride Inorganic materials 0.000 description 3
- 239000002245 particle Substances 0.000 description 3
- 229920000573 polyethylene Polymers 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 2
- MQIUGAXCHLFZKX-UHFFFAOYSA-N Di-n-octyl phthalate Natural products CCCCCCCCOC(=O)C1=CC=CC=C1C(=O)OCCCCCCCC MQIUGAXCHLFZKX-UHFFFAOYSA-N 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-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
- 238000010521 absorption reaction Methods 0.000 description 2
- 150000003973 alkyl amines Chemical class 0.000 description 2
- 239000003945 anionic surfactant Substances 0.000 description 2
- 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 2
- 239000006229 carbon black Substances 0.000 description 2
- 230000015556 catabolic process Effects 0.000 description 2
- 239000003093 cationic surfactant Substances 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 238000003851 corona treatment Methods 0.000 description 2
- DIOQZVSQGTUSAI-UHFFFAOYSA-N decane Chemical compound CCCCCCCCCC DIOQZVSQGTUSAI-UHFFFAOYSA-N 0.000 description 2
- 238000006731 degradation reaction Methods 0.000 description 2
- 238000003795 desorption Methods 0.000 description 2
- 235000014113 dietary fatty acids Nutrition 0.000 description 2
- 238000001035 drying Methods 0.000 description 2
- 239000000194 fatty acid Substances 0.000 description 2
- 229930195729 fatty acid Natural products 0.000 description 2
- 150000002500 ions Chemical class 0.000 description 2
- 239000010410 layer Substances 0.000 description 2
- 229910052744 lithium Inorganic materials 0.000 description 2
- 229910003002 lithium salt Inorganic materials 0.000 description 2
- 159000000002 lithium salts Chemical class 0.000 description 2
- 239000012528 membrane Substances 0.000 description 2
- 239000012229 microporous material Substances 0.000 description 2
- GOQYKNQRPGWPLP-UHFFFAOYSA-N n-heptadecyl alcohol Natural products CCCCCCCCCCCCCCCCCO GOQYKNQRPGWPLP-UHFFFAOYSA-N 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- PXHVJJICTQNCMI-UHFFFAOYSA-N nickel Substances [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 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
- 230000035515 penetration Effects 0.000 description 2
- 229920000306 polymethylpentene Polymers 0.000 description 2
- 239000011116 polymethylpentene Substances 0.000 description 2
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- 238000011160 research Methods 0.000 description 2
- 229930195734 saturated hydrocarbon Natural products 0.000 description 2
- 238000006277 sulfonation reaction Methods 0.000 description 2
- 239000010409 thin film Substances 0.000 description 2
- 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 1
- 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
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 1
- 239000004593 Epoxy Substances 0.000 description 1
- 238000010306 acid treatment Methods 0.000 description 1
- 239000012190 activator Substances 0.000 description 1
- 239000013543 active substance Substances 0.000 description 1
- 150000001298 alcohols Chemical class 0.000 description 1
- 239000003513 alkali Substances 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
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 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
- 150000001450 anions Chemical class 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
- 229940077388 benzenesulfonate Drugs 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 150000001768 cations Chemical class 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000013329 compounding Methods 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 238000005520 cutting process Methods 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 230000006866 deterioration Effects 0.000 description 1
- ZBCBWPMODOFKDW-UHFFFAOYSA-N diethanolamine Chemical class OCCNCCO ZBCBWPMODOFKDW-UHFFFAOYSA-N 0.000 description 1
- 239000006185 dispersion Substances 0.000 description 1
- 239000000598 endocrine disruptor Substances 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
- 239000003063 flame retardant Substances 0.000 description 1
- 239000011888 foil Substances 0.000 description 1
- 238000007429 general method Methods 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 230000002209 hydrophobic effect Effects 0.000 description 1
- 238000005470 impregnation Methods 0.000 description 1
- 239000012535 impurity Substances 0.000 description 1
- 229910052738 indium Inorganic materials 0.000 description 1
- 238000005342 ion exchange Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- JWZCKIBZGMIRSW-UHFFFAOYSA-N lead lithium Chemical compound [Li].[Pb] JWZCKIBZGMIRSW-UHFFFAOYSA-N 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000010687 lubricating oil Substances 0.000 description 1
- 239000003595 mist Substances 0.000 description 1
- 229920003986 novolac Polymers 0.000 description 1
- TVMXDCGIABBOFY-UHFFFAOYSA-N octane Chemical compound CCCCCCCC TVMXDCGIABBOFY-UHFFFAOYSA-N 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 238000010525 oxidative degradation reaction Methods 0.000 description 1
- 239000012188 paraffin wax Substances 0.000 description 1
- 150000002989 phenols Chemical class 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920001083 polybutene Polymers 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 229920001343 polytetrafluoroethylene Polymers 0.000 description 1
- 239000004810 polytetrafluoroethylene Substances 0.000 description 1
- 238000012545 processing Methods 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
- 239000000243 solution Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- HIFJUMGIHIZEPX-UHFFFAOYSA-N sulfuric acid;sulfur trioxide Chemical compound O=S(=O)=O.OS(O)(=O)=O HIFJUMGIHIZEPX-UHFFFAOYSA-N 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 230000002195 synergetic effect Effects 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
- Y02E60/10—Energy storage using batteries
Abstract
Description
本発明は、電解液が実質的にイオン液体のみ又は実質的にイオン液体と電解質塩のみで構成される蓄電デバイスに用いるセパレータと該セパレータを用いた蓄電デバイスに関する。 The present invention relates to a separator used for an electricity storage device in which an electrolytic solution is substantially only an ionic liquid or substantially only an ionic liquid and an electrolyte salt, and an electricity storage device using the separator.
近年、主に自動車用、産業用（最近では住宅用も）の汎用の蓄電デバイスとして、鉛蓄電池やニッケル水素電池に代わって、鉛のような有害物質を用いずより高性能（高エネルギー密度）かつ軽量な、リチウムイオン電池が大きく普及し始めているが、リチウムイオン電池は、鉛蓄電池やニッケル水素電池が酸やアルカリの水溶液系の電解液を用いているのに対し、水の分解電圧（１．２Ｖ）を超える高電圧を実現するため及びリチウムが水を嫌うために、リチウム塩と有機溶媒（カーボネート系溶媒）からなる電解液を用いていることから、電解液は揮発性が高く可燃性であるため高い引火性を有し、過充電や短絡等の温度上昇時に、電池が引火（発火）、爆発する危険性があり、鉛蓄電池やニッケル水素電池に比べると、安全性の面で大きな課題を残している。 In recent years, as a general-purpose electricity storage device mainly for automobiles and industrial use (and recently for residential use), instead of lead-acid batteries and nickel metal hydride batteries, higher performance (high energy density) without using harmful substances such as lead Lithium ion batteries, which are light and lightweight, are beginning to become widely used. However, in the case of lithium ion batteries, lead acid batteries and nickel metal hydride batteries use an aqueous electrolyte solution of acid or alkali, whereas the decomposition voltage of water (1 .2V) to achieve high voltage and because lithium dislikes water, the electrolyte is composed of lithium salt and organic solvent (carbonate solvent), so the electrolyte is highly volatile and flammable. Therefore, it has high flammability, and there is a danger that the battery will ignite (ignition) and explode when the temperature rises due to overcharge or short circuit. Compared to lead-acid batteries and nickel-metal hydride batteries, it is much safer. It has left a problem.
そこで、このような引火の危険性を有する電解液に代わり、安全性の高い電解液として、イオン液体に着目した研究が進められている（例えば、特許文献１〜２）。イオン液体は、主に、１００℃以下（明確な規定はない）の低温で液体である溶融塩で、イオンのみ（カチオンとアニオンのみ）からなる液体であり、難揮発性で、難燃性であり、非常に安全性が高くなる。ただし、現在はまだ研究段階であり、実用に向けた主な課題として、粘性が高い、価格が高いなどの課題がある。 Therefore, research focusing on ionic liquids is being promoted as a highly safe electrolytic solution instead of the electrolytic solution having the risk of ignition (for example, Patent Documents 1 and 2). An ionic liquid is mainly a molten salt that is a liquid at a low temperature of 100 ° C. or lower (no specific provisions), and is a liquid consisting of only ions (only cations and anions). It is hardly volatile and flame retardant. Yes, it is very safe. However, it is still in the research stage, and there are issues such as high viscosity and high price as main issues for practical use.
また、イオン液体は、粘性が高く、表面張力が高いため、従来の有機溶媒系の電解液に用いられている単層タイプのポリオレフィン系樹脂製微多孔性フィルム（フィルム組成は基本的にポリオレフィン系樹脂のみからなるもの。旭化成イーマテリアルズ社「ハイポア」（登録商標）、宇部興産社「ユーポア」（登録商標）、東レバッテリーセパレータフィルム社「セティーラ」（登録商標）、ポリポア社「セルガード」（登録商標）など。）をそのままセパレータとして用いた場合は、電池がドライアップし、目的の電池性能が得られないという問題がある。尚、ここでは、電解液として実質的にイオン液体のみ又はイオン液体と電解質塩のみで構成される電池を想定している。 In addition, since ionic liquids have high viscosity and high surface tension, they are single layer type microporous films made of polyolefin resin that are used in conventional organic solvent electrolytes. Consists of resin only: Asahi Kasei E-materials "Hypore" (registered trademark), Ube Industries "Yupor" (registered trademark), Toray Battery Separator Film Company "Cetilla" (registered trademark), Polypore "Celguard" (registered) If the product is used as a separator as it is, there is a problem that the battery is dried up and the desired battery performance cannot be obtained. Here, it is assumed that the battery is substantially composed of only the ionic liquid or only the ionic liquid and the electrolyte salt as the electrolytic solution.
これは、イオン液体の表面張力が高いため、ポリオレフィン系樹脂製微多孔性フィルムの臨界表面張力を超え、セパレータの電解液濡れ性（電解液浸透性、電解液保持性）が良好ではないためと思われる。 This is because the surface tension of the ionic liquid is high, which exceeds the critical surface tension of the microporous film made of polyolefin resin, and the electrolyte wettability (electrolyte permeability, electrolyte retention) of the separator is not good. Seem.
そこで、ポリオレフィン系樹脂製のセパレータに対し、親水化処理を施すことが考えられる。樹脂製フィルム基材に対する一般的な親水化の方法として、（１）基材に対してコロナ放電処理を施す方法、（２）基材に対してスルホン化処理（発煙硫酸処理）を施す方法、（３）基材を得る際に親水基を有する材料（ＰＶＡ）を配合する方法があるが、ポリオレフィン系樹脂製微多孔性フィルム基材（単層タイプでフィルム組成は基本的にポリオレフィン系樹脂のみからなるもの、旭化成イーマテリアルズ社「ハイポア」（登録商標）、宇部興産社「ユーポア」（登録商標）、東レバッテリーセパレータフィルム社「セティーラ」（登録商標）、ポリポア社「セルガード」（登録商標）など）においてこれらの方法を適用すると、（１）のコロナ放電処理を施す方法では、多孔性基材の細孔内表面（孔の奥）は親水性が付与されない、（２）のスルホン化処理を施す方法では、ポリオレフィン系樹脂が劣化する、（３）の親水基を有する材料を配合する方法では、フィルムへの加工がしにくくなる、基材が酸化劣化しやすくなる、といった問題があり、良好な親水化基材（ポリオレフィン系樹脂製微多孔性フィルム）を得ることはできない。 Therefore, it is conceivable to perform a hydrophilic treatment on the separator made of polyolefin resin. As a general hydrophilization method for a resin film base material, (1) a method for subjecting the base material to corona discharge treatment, (2) a method for subjecting the base material to sulfonation (fuming sulfuric acid treatment), (3) Although there is a method of blending a material having a hydrophilic group (PVA) when obtaining a substrate, a microporous film substrate made of polyolefin resin (single layer type, and the film composition is basically only polyolefin resin) Asahi Kasei E-materials "Hypore" (registered trademark), Ube Industries "Yupor" (registered trademark), Toray Battery Separator Film Company "Cetilla" (registered trademark), Polypore "Celguard" (registered trademark) In the method of applying the corona discharge treatment of (1), hydrophilicity is not imparted to the pore inner surface (the back of the pore) of the porous substrate. ) In the method of applying the sulfonation treatment, the polyolefin-based resin is deteriorated, in the method of blending the material having a hydrophilic group in (3), it becomes difficult to process the film, and the base material is easily oxidized and deteriorated. Therefore, it is not possible to obtain a good hydrophilic substrate (polyolefin-based microporous film).
そこで、更に、樹脂製フィルム基材に対する一般的な親水化の方法として、上記したような方法よりも簡便でコストが安価となる、界面活性剤を添加する方法があり、ポリオレフィン系樹脂製微多孔性フィルム基材（単層タイプでフィルム組成は基本的にポリオレフィン系樹脂のみからなるもの、旭化成イーマテリアルズ社「ハイポア」（登録商標）、宇部興産社「ユーポア」（登録商標）、東レバッテリーセパレータフィルム社「セティーラ」（登録商標）、ポリポア社「セルガード」（登録商標）など）においてこの方法を適用すると、確かに、多孔性基材の細孔内外表面（孔の外表面と孔の奥）に親水性が付与され、この多孔性基材（ポリオレフィン系樹脂製微多孔性フィルム）をセパレータとして用いてイオン液体を電解液とする蓄電デバイスを構成した場合に、当初の電解液濡れ性（電解液浸透性、電解液保持性）は良好となるが、蓄電デバイスの使用に伴う時間の経過とともに、多孔性基材の親水性が徐々に失われ（電解液濡れ性、つまり電解液保持性が低下し）、蓄電デバイスはドライアップを引き起こす。 Therefore, there is a method of adding a surfactant that is simpler and less expensive than the above-described method as a general method for hydrophilizing a resin film substrate. Film base material (single layer type, consisting essentially of polyolefin resin, Asahi Kasei E-Materials "Hypore" (registered trademark), Ube Industries "Eupor" (registered trademark), Toray Battery Separator When this method is applied to Film Corporation “Cetilla” (registered trademark), Polypore “Celguard” (registered trademark), etc., the inner and outer surfaces of the pores of the porous substrate (the outer surface of the pores and the inner surface of the pores) The porous substrate (polyolefin-based microporous film) is used as a separator to store ionic liquid as an electrolyte. When the device is configured, the initial electrolyte wettability (electrolyte permeability, electrolyte retention) is good, but the hydrophilicity of the porous substrate gradually increases with the passage of time associated with the use of the electricity storage device. (Electrolytic solution wettability, that is, electrolyte solution retention is reduced), and the electricity storage device causes dry-up.
この現象について、本出願人は、次のように推定（解明）した。つまり、ポリオレフィン系樹脂製微多孔性フィルム基材（単層タイプでフィルム組成は基本的にポリオレフィン系樹脂のみからなるもの、旭化成イーマテリアルズ社「ハイポア」（登録商標）、宇部興産社「ユーポア」（登録商標）、東レバッテリーセパレータフィルム社「セティーラ」（登録商標）、ポリポア社「セルガード」（登録商標）など）において、その基材表面（細孔内外表面）は、基本的にアルキル基のみが存在しており、界面活性剤を添加すると、親油基（疎水基）と親水基を有する界面活性剤分子は、ポリオレフィン系樹脂製微多孔性フィルム基材の表面（細孔内外表面）のアルキル基（疎水基）に付着し、同基材に親水性を付与するが、蓄電デバイスの使用に伴う時間の経過とともに、ポリオレフィン系樹脂製微多孔性フィルム基材の表面（細孔内外表面）のアルキル基に付着していた界面活性剤分子が徐々に（電解液中へ）遊離（脱離）していくものと推定した。 About this phenomenon, the present applicant estimated (clarified) as follows. In other words, microporous film substrate made of polyolefin resin (single layer type, film composition consisting essentially of polyolefin resin, Asahi Kasei E-Materials “Hypore” (registered trademark), Ube Industries Ltd. “Yupore” (Registered trademark), Toray Battery Separator Film Co., Ltd. “Cetilla” (registered trademark), Polypore “Celguard” (registered trademark), etc. When a surfactant is added, the surfactant molecule having a lipophilic group (hydrophobic group) and a hydrophilic group becomes alkyl on the surface of the microporous film substrate made of polyolefin resin (inside and outside surfaces of the pores). Attached to a group (hydrophobic group) and imparts hydrophilicity to the same substrate, but with the passage of time associated with the use of electricity storage devices, polyolefin resin microporosity Irumu surfactant molecules having adhered to the alkyl groups on the surface (pore inner and outer surfaces) of the substrate (the electrolyte solution) was slowly assumed to continue to free (desorption).
本発明では、前記従来の問題点に鑑み、電解液が実質的にイオン液体のみ又は実質的にイオン液体と電解質塩のみで構成される蓄電デバイスに用いる、ポリオレフィン系樹脂を骨格材としてなる微多孔性フィルムセパレータにおいて、当初の電解液濡れ性（電解液浸透性、電解液保持性）が良好であるとともに、蓄電デバイスの使用に伴う時間経過後も良好な電解液濡れ性（電解液保持性）を維持することのできるセパレータを提供することを目的とする。 In the present invention, in view of the above-mentioned conventional problems, a microporous material using a polyolefin-based resin as a skeleton material, which is used for an electricity storage device in which an electrolyte is substantially composed of only an ionic liquid or substantially only an ionic liquid and an electrolyte salt. Electrolytic film separator has good initial electrolyte wettability (electrolyte permeability, electrolyte retainability) and good electrolyte wettability (electrolyte retainability) even after the lapse of time associated with the use of electricity storage devices An object is to provide a separator capable of maintaining the above.
本発明者等は、前記目的を達成するべく、鋭意検討を行った結果、次のような知見を得た。つまり、前記解明した従来の現象に基づき、界面活性剤による親水化を施すポリオレフィン系樹脂製微多孔性フィルムセパレータの考え方において、蓄電デバイスの時間経過後も界面活性剤分子が遊離（脱離）しにくくなるよう、微多孔性フィルムの細孔内外表面への界面活性剤分子の定着力を高めるため、ポリオレフィン系樹脂を骨格材としてなる微多孔性フィルムにおいて、比表面積が大きく親水性の高い無機粉体を多量に含有させることで、ポリオレフィン系樹脂製微多孔性フィルム基材の表面（細孔内外表面）に、ポリオレフィン系樹脂に基づくアルキル基（疎水基）とは別に、無機粉体に基づく親水基を多量に存在させるようにすることで、ポリオレフィン系樹脂製微多孔性フィルム基材に、親水性付与のために界面活性剤の添加を行った場合、親油基（疎水基）と親水基を有する界面活性剤分子は、ポリオレフィン系樹脂製微多孔性フィルム基材の表面（細孔内外表面）の、ポリオレフィン系樹脂に基づくアルキル基（疎水基）、及び、無機粉体に基づく多量の親水基に付着し、同基材に高い親水性を付与することができ、イオン液体が主体の電解液からなる蓄電デバイス用セパレータとして用いた場合に、当初の電解液濡れ性（電解液浸透性、電解液保持性）を良好となし、一方、蓄電デバイスの使用に伴う時間の経過とともに、同基材の表面（細孔内外表面）のポリオレフィン系樹脂に基づくアルキル基（疎水基）に付着していた界面活性剤分子は徐々に遊離（脱離）していくが、同基材の表面（細孔内外表面）の無機粉体に基づく多量の親水基に付着していた界面活性剤分子は遊離（脱離）を生じにくく、同基材全体として、高い親水性を維持し、良好な電解液濡れ性（電解液保持性）を維持することができることを知見した。 As a result of intensive studies to achieve the above object, the present inventors have obtained the following knowledge. In other words, based on the above-explained conventional phenomenon, in the concept of a polyolefin resin microporous film separator that is hydrophilized with a surfactant, surfactant molecules are released (desorbed) even after the storage device has elapsed. In order to increase the fixing power of surfactant molecules on the inside and outside pores of the microporous film, the inorganic powder has a large specific surface area and high hydrophilicity. In addition to the alkyl group (hydrophobic group) based on the polyolefin resin, the surface of the microporous film substrate made of polyolefin resin (inside and outside surfaces of the pores) can be made hydrophilic based on inorganic powder. By adding a large amount of groups, a surfactant is added to the polyolefin resin microporous film substrate to impart hydrophilicity. When performed, the surfactant molecule having a lipophilic group (hydrophobic group) and a hydrophilic group is an alkyl group (based on the polyolefin resin) on the surface of the polyolefin resin microporous film substrate (inside / outside pore surface). Hydrophobic groups) and when attached to a large amount of hydrophilic groups based on inorganic powder, can impart high hydrophilicity to the same substrate, and is used as a separator for an electricity storage device consisting of an electrolyte mainly composed of an ionic liquid In addition, the initial electrolyte wettability (electrolyte permeability, electrolyte retainability) is good, while the surface of the same base material (inside and outside surfaces of the pores) polyolefin over time with the use of the electricity storage device The surfactant molecules attached to the alkyl group (hydrophobic group) based on the resin are gradually released (desorbed), but a large amount based on the inorganic powder on the surface of the substrate (inside and outside of the pores) The field attached to the hydrophilic group of Active agent molecules hardly occurs free (desorption), as a whole the substrate to maintain a high hydrophilicity, and found that it is possible to maintain good electrolyte wettability (electrolyte retention).
本発明の上記考え方によれば、粘性が高く、表面張力が高いとされるイオン液体、特に、表面張力（２５℃、懸滴法）が４８ｍＮ／ｍ以上、更には５３ｍＮ／ｍ以上であるイオン液体を用いる場合において、本発明の前記目的を達成し得ることも分かった。そのために、界面活性剤を添加するにおいて、無機粉体を多量に含有させること、比表面積の大きい無機粉体を使用すること、親水性が優れた無機粉体を使用することの組み合わせによる相乗効果が大きく作用することも分かった。 According to the above concept of the present invention, an ionic liquid having a high viscosity and a high surface tension, particularly an ion having a surface tension (25 ° C., hanging drop method) of 48 mN / m or more, more preferably 53 mN / m or more. It has also been found that the object of the present invention can be achieved in the case of using a liquid. Therefore, in adding a surfactant, a synergistic effect by combining a large amount of inorganic powder, using an inorganic powder with a large specific surface area, and using an inorganic powder with excellent hydrophilicity It was also found that acted greatly.
本発明は、このような知見に基づきなされた発明であって、本発明の蓄電デバイス用セパレータは、請求項１に記載の通り、電解液が、表面張力（２５℃、懸滴法）４８ｍＮ／ｍ以上のイオン液体を用いて、実質的に前記イオン液体のみ又は実質的に前記イオン液体と電解質塩のみで構成される蓄電デバイスに用いるセパレータであって、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し圧延及び／又は延伸による薄肉化成形と前記可塑剤の除去を行って得られる、厚さが１０〜１００μｍ、平均孔径が０．０１〜０．５μｍ、空隙率が５０〜９０％である微多孔性フィルムからなり、前記無機粉体がＢＥＴ比表面積１００ｍ２／ｇ以上で疎水化度５％以下の親水性無機粉体で、前記原料組成物中には界面活性剤を含有し、前記無機粉体の含有量が４０〜８０質量％、前記界面活性剤（固形分）の含有量が１〜１５質量％、前記ポリオレフィン系樹脂の含有量が２０〜６０質量％であることを特徴とする。 The present invention is an invention based on such knowledge, and the separator for an electricity storage device according to the present invention has an electrolyte having a surface tension (25 ° C., hanging drop method) of 48 mN / A separator for use in an electricity storage device that is substantially composed of only the ionic liquid or substantially only the ionic liquid and an electrolyte salt using an ionic liquid of m or more, and comprising a polyolefin-based resin, an inorganic powder, and a plasticizer Obtained by melt-kneading and forming a raw material composition mainly composed of a thin film by rolling and / or stretching and removing the plasticizer, and having a thickness of 10 to 100 μm and an average pore diameter of 0.01 to The raw material is a hydrophilic porous inorganic powder having a BET specific surface area of 100 m 2 / g and a hydrophobization degree of 5% or less, comprising a microporous film of 0.5 μm and a porosity of 50 to 90%. In the composition It contains a surfactant, the inorganic powder content is 40-80% by mass, the surfactant (solid content) content is 1-15% by mass, and the polyolefin resin content is 20-60. It is characterized by mass%.
また、本発明の蓄電デバイス用セパレータは、請求項２に記載の通り、電解液が、表面張力（２５℃、懸滴法）４８ｍＮ／ｍ以上のイオン液体を用いて、実質的に前記イオン液体のみ又は実質的に前記イオン液体と電解質塩のみで構成される蓄電デバイスに用いるセパレータであって、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し圧延及び／又は延伸による薄肉化成形と前記可塑剤の除去を行って得られる、厚さが１０〜１００μｍ、平均孔径が０．０１〜０．５μｍ、空隙率が５０〜９０％である微多孔性フィルムからなり、前記無機粉体がＢＥＴ比表面積１００ｍ２／ｇ以上で疎水化度５％以下の親水性無機粉体で、前記原料組成物中には含有せず前記微多孔性フィルム中には界面活性剤を含有し、前記無機粉体の含有量が４０〜８０質量％、前記界面活性剤（固形分）の含有量が０．５〜７質量％、前記ポリオレフィン系樹脂の含有量が２０〜６０質量％であることを特徴とする。 The separator for an electricity storage device of the present invention is substantially the ionic liquid as described in claim 2 using an ionic liquid having an electrolyte of 48 mN / m or more in surface tension (25 ° C., hanging drop method). A separator for use in an electricity storage device composed of only the ionic liquid and an electrolyte salt, and melt-kneaded a raw material composition mainly composed of a polyolefin-based resin, an inorganic powder, and a plasticizer to form a film. A microporous material having a thickness of 10 to 100 μm, an average pore diameter of 0.01 to 0.5 μm, and a porosity of 50 to 90%, obtained by performing thinning molding by rolling and / or stretching and removing the plasticizer. The inorganic powder is a hydrophilic inorganic powder having a BET specific surface area of 100 m 2 / g or more and a hydrophobicity of 5% or less, and is not contained in the raw material composition. Contains surfactant The content of the inorganic powder is 40 to 80% by mass, the content of the surfactant (solid content) is 0.5 to 7% by mass, and the content of the polyolefin resin is 20 to 60% by mass. It is characterized by being.
また、本発明の蓄電デバイスは、請求項３に記載の通り、電解液が、表面張力（２５℃、懸滴法）４８ｍＮ／ｍ以上のイオン液体を用いて、実質的に前記イオン液体のみ又は実質的に前記イオン液体と電解質塩のみで構成される、請求項１又は２に記載のセパレータを使用したことを特徴とする。 Moreover, the electricity storage device of the present invention is as described in claim 3, wherein the electrolytic solution is an ionic liquid having a surface tension (25 ° C., hanging drop method) of 48 mN / m or more. The separator according to claim 1, wherein the separator is substantially composed only of the ionic liquid and an electrolyte salt.
本発明によれば、電解液が実質的にイオン液体のみ又は実質的にイオン液体と電解質塩のみで構成される蓄電デバイスに用いる、ポリオレフィン系樹脂を骨格材としてなる微多孔性フィルムセパレータにおいて、当初の電解液濡れ性（電解液浸透性、電解液保持性）が良好であるとともに、蓄電デバイスの使用に伴う時間経過後も良好な電解液濡れ性（電解液保持性）を維持することのできるセパレータを提供することができる。 According to the present invention, in a microporous film separator having a polyolefin-based resin as a skeleton material, used in an electricity storage device in which an electrolyte solution is substantially composed of only an ionic liquid or substantially only an ionic liquid and an electrolyte salt. Electrolytic solution wettability (electrolytic solution permeability, electrolytic solution holding property) can be maintained, and good electrolytic solution wettability (electrolytic solution holding property) can be maintained even after elapse of time associated with the use of the electricity storage device. A separator can be provided.
本発明のセパレータを構成する微多孔性フィルムは、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し圧延及び／又は延伸による薄肉化成形と前記可塑剤の除去を行って得られる、厚さが１０〜１００μｍ、平均孔径が０．０１〜０．５μｍ、空隙率が５０〜９０％である微多孔性フィルムである。
しかも、無機粉体がＢＥＴ比表面積１００ｍ２／ｇ以上で疎水化度５％以下の親水性無機粉体で、原料組成物中に界面活性剤を含有するか、原料組成物中には含有せず微多孔性フィルム中に界面活性剤を含有し、無機粉体の含有量が４０〜８０質量％、界面活性剤（固形分）の含有量が１〜１５質量％（原料組成物中に界面活性剤を含有する場合）又は０．５〜７質量％（原料組成物中には含有せず微多孔性フィルム中に界面活性剤を含有する場合）、ポリオレフィン系樹脂の含有量が２０〜６０質量％であることが必要である。
尚、微多孔性フィルムの空隙率は、５０％以上であることで、蓄電デバイス用セパレータとして内部抵抗を低く抑えることができ、蓄電デバイスの高性能化に寄与する。よって、微多孔性フィルムの空隙率は、６０〜９０％、更には７０〜９０％であることがより好ましい。
The microporous film constituting the separator of the present invention is formed by melting and kneading a raw material composition mainly composed of a polyolefin-based resin, an inorganic powder, and a plasticizer to form a thin film by rolling and / or stretching and the plastic. A microporous film having a thickness of 10 to 100 μm, an average pore diameter of 0.01 to 0.5 μm, and a porosity of 50 to 90%, obtained by removing the agent.
Moreover, the inorganic powder is a hydrophilic inorganic powder having a BET specific surface area of 100 m 2 / g or more and a hydrophobization degree of 5% or less. The raw material composition contains a surfactant or is contained in the raw material composition. The microporous film contains a surfactant, the inorganic powder content is 40 to 80% by mass, the surfactant (solid content) content is 1 to 15% by mass (the interface in the raw material composition) When containing an activator) or 0.5 to 7% by mass (when not containing in the raw material composition and containing a surfactant in the microporous film), the polyolefin resin content is 20 to 60 It is necessary to be mass%.
In addition, when the porosity of the microporous film is 50% or more, the internal resistance can be kept low as a separator for an electricity storage device, which contributes to high performance of the electricity storage device. Therefore, the porosity of the microporous film is more preferably 60 to 90%, and even more preferably 70 to 90%.
これにより、ポリオレフィン系樹脂を骨格材としてなる微多孔性フィルムにあって、電解液が実質的に表面張力４８ｍＮ／ｍ以上のイオン液体のみ又は実質的に表面張力４８ｍＮ／ｍ以上のイオン液体と電解質塩のみで構成される蓄電デバイス用のセパレータとして用いた場合に、当初の電解液濡れ性（電解液浸透性、電解液保持性）が良好であるとともに、蓄電デバイスの使用に伴う時間経過後も良好な電解液濡れ性（電解液保持性）を維持することができるようになる。 Thereby, in a microporous film having a polyolefin-based resin as a skeleton material, the electrolyte is substantially only an ionic liquid having a surface tension of 48 mN / m or more, or an ionic liquid and an electrolyte having a surface tension of 48 mN / m or more. When used as a separator for an electricity storage device composed of only salt, the initial electrolyte wettability (electrolyte permeability, electrolyte retention) is good, and after the passage of time associated with the use of the electricity storage device Good electrolyte solution wettability (electrolytic solution retention) can be maintained.
本発明の微多孔性フィルムは、１００ｍ２／ｇ以上という比表面積が大きくて疎水化度が５％以下という親水性の高い無機粉体を含有量が４０〜８０質量％と多量に含む。これにより、ポリオレフィン系樹脂を骨格材としてなる微多孔性フィルムにおいて、比表面積が大きく親水性が高い無機粉体を多量に含有させることで、ポリオレフィン系樹脂製微多孔性フィルム基材の表面（細孔内外表面）に、ポリオレフィン系樹脂に基づくアルキル基（疎水基）とは別に、無機粉体に基づく親水基を多量に存在させるようにすることで、ポリオレフィン系樹脂製微多孔性フィルム基材に、親水性付与のために界面活性剤の添加を行うと、親油基（疎水基）と親水基を有する界面活性剤分子は、ポリオレフィン系樹脂製微多孔性フィルム基材の表面（細孔内外表面）の、ポリオレフィン系樹脂に基づくアルキル基（疎水基）、及び、無機粉体に基づく多量の親水基に付着し、同基材に高い親水性を付与することができる。 The microporous film of the present invention contains a large amount of inorganic powder having a high specific surface area of 100 m 2 / g or more and a hydrophobization degree of 5% or less, such as high hydrophilicity, of 40 to 80% by mass. As a result, in a microporous film having a polyolefin resin as a skeleton material, a large amount of inorganic powder having a large specific surface area and high hydrophilicity is contained, so that the surface of the polyolefin resin microporous film substrate (fine In addition to alkyl groups (hydrophobic groups) based on polyolefin resins on the inner and outer surfaces of the pores, a large amount of hydrophilic groups based on inorganic powders can be present in a microporous film substrate made of polyolefin resin. When a surfactant is added to impart hydrophilicity, the surfactant molecule having a lipophilic group (hydrophobic group) and a hydrophilic group is added to the surface of the microporous film substrate made of polyolefin resin (inside and outside the pores). It adheres to the alkyl group (hydrophobic group) based on the polyolefin resin on the surface) and a large amount of hydrophilic groups based on the inorganic powder, and can impart high hydrophilicity to the substrate.
このような微多孔性フィルム基材を、電解液が実質的に表面張力４８ｍＮ／ｍ以上のイオン液体のみ又は実質的に表面張力４８ｍＮ／ｍ以上のイオン液体と電解質塩のみで構成される蓄電デバイス用のセパレータとして用いた場合、当初の電解液濡れ性（電解液浸透性、電解液保持性）を良好となし、一方、蓄電デバイスの使用に伴う時間の経過とともに、同基材の表面（細孔内外表面）のポリオレフィン系樹脂に基づくアルキル基（疎水基）に付着していた界面活性剤分子は徐々に遊離（脱離）していくが、同基材の表面（細孔内外表面）の無機粉体に基づく多量の親水基に付着していた界面活性剤分子は遊離（脱離）を生じにくく、同基材全体として、高い親水性を維持し、良好な電解液濡れ性（電解液保持性）を維持することができる。 An electricity storage device in which such a microporous film substrate is composed of only an ionic liquid having a surface tension of 48 mN / m or more or an ionic liquid and an electrolyte salt having a surface tension of 48 mN / m or more. When used as a separator, the initial electrolyte wettability (electrolyte permeability, electrolyte retention) is good. On the other hand, the surface of the substrate (fine Surfactant molecules adhering to the alkyl group (hydrophobic group) based on the polyolefin resin on the inner and outer surfaces of the pores gradually release (desorb), but the surface of the substrate (the inner and outer surfaces of the pores) Surfactant molecules attached to a large amount of hydrophilic groups based on inorganic powder are less likely to be released (desorbed), maintain high hydrophilicity as a whole of the base material, and have good electrolyte wettability (electrolyte solution) Retainability)
つまり、ポリオレフィン系樹脂の含有量が２０〜６０質量％であるポリオレフィン系樹脂を骨格材としてなる微多孔性フィルムにあって、ＢＥＴ比表面積が１００ｍ２／ｇ以上で疎水化度が５％以下の親水性の高い無機粉体を４０質量％以上と多量に含ませた上で、界面活性剤を固形分で１〜１５質量％（原料組成物中に界面活性剤を含有する場合）又は０．５〜７質量％（原料組成物中に含有せず微多孔性フィルム中に界面活性剤を含有する場合）含ませるようにしたことで、実質的に表面張力４８ｍＮ／ｍ以上のイオン液体のみ又は実質的に表面張力４８ｍＮ／ｍ以上のイオン液体と電解質塩のみで構成される電解液からなる蓄電デバイス用のセパレータとして、セパレータの高い親水性を持続し、電解液に対する濡れ性を持続して、蓄電デバイスのドライアップを防止し、蓄電デバイスの性能を向上させることができるものである。 That is, in a microporous film having a polyolefin resin having a polyolefin resin content of 20 to 60% by mass as a skeleton material, the BET specific surface area is 100 m 2 / g or more and the degree of hydrophobicity is 5% or less. After containing a large amount of inorganic powder having a high hydrophilicity of 40% by mass or more, 1 to 15% by mass (when the surfactant is contained in the raw material composition) of the surfactant in a solid content, or 0. By including 5 to 7% by mass (when the surfactant is contained in the microporous film but not contained in the raw material composition), only the ionic liquid having a surface tension of 48 mN / m or more substantially or As a separator for an electricity storage device consisting of an electrolytic solution composed only of an ionic liquid having a surface tension of 48 mN / m or more and an electrolyte salt, the separator has a high hydrophilicity and maintains a wettability to the electrolytic solution. Preventing dry-up of the electric devices, it is capable of improving the performance of the electric storage device.
ポリオレフィン系樹脂は、本発明の微多孔性フィルムにおいて骨格材をなす材料である。ポリオレフィン系樹脂としては、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又は共重合体及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、無機粉体を多量に含み厚さが１０〜１００μｍの薄肉となる本発明の微多孔性フィルムにあって、微多孔性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、本発明の微多孔性フィルムにあって無機粉体とともに骨格を形成し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、特に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）等の高融点又は高軟化点の樹脂を併用することが好ましい。 The polyolefin-based resin is a material that forms a skeleton material in the microporous film of the present invention. As the polyolefin resin, 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. The polyolefin-based resin is a microporous film of the present invention having a weight average molecular weight of 500,000 or more and a large amount of inorganic powder and a thickness of 10 to 100 μm. Mechanical strength can be ensured. Therefore, the polyolefin resin preferably has a weight average molecular weight of 1 million or more. Polyolefin resin has good mixing properties with inorganic powder, and in the microporous film of the present invention, forms a skeleton together with inorganic powder to maintain strength, and is chemically stable and highly safe. . 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), especially for applications requiring heat resistance. It is preferable.
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ＢＥＴ比表面積が１００ｍ２／ｇ以上で、疎水化度が５％以下の高い親水性であるシリカ、アルミナ、チタニア等の１種又は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、疎水化度が５％以下であることで、粉体表面に親水基（−ＯＨ）を多く備えることができ（高い親水性を有し）、微多孔性フィルムに高い親水性を与える。そのため、無機粉体の疎水化度は２％以下、更には０％であることがより好ましい。また、無機粉体は、ＢＥＴ比表面積が１００ｍ２／ｇ以上であることで、微多孔性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、微多孔性フィルムの電解液保持力を高め、粉体表面に親水基（−ＯＨ）を多く備えられること（疎水化度が５％以下で親水性の高いことが前提）により微多孔性フィルムの親水性を高めることができる。そのため、無機粉体のＢＥＴ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ＢＥＴ比表面積は４００ｍ２／ｇ以下であることが好ましい。無機粉体のＢＥＴ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、微多孔性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。平均二次粒子径は、得られた微多孔性フィルムにおいてピンホールが発生するのを抑えるため、５μｍ以下であることが好ましい。 As the inorganic powder, BET specific surface area particle size with a pore structure finer inside or surface at 100 m 2 / g or more, the silica hydrophobic degree is 5% or less of the high hydrophilicity, alumina, titania, etc. 1 type (s) or 2 or more types 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 hydrophobization degree of 5% or less, so that it can have many hydrophilic groups (—OH) on the powder surface (having high hydrophilicity) and high hydrophilicity in the microporous film. give. Therefore, the degree of hydrophobicity of the inorganic powder is preferably 2% or less, and more preferably 0%. In addition, the inorganic powder has a BET 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 short circuit resistance, and the electrolyte holding power of the microporous film can be increased. The hydrophilicity of the microporous film can be enhanced by increasing the amount of hydrophilic groups (—OH) on the powder surface (assuming that the degree of hydrophobicity is 5% or less and high hydrophilicity). Therefore, the BET specific surface area of the inorganic powder is more preferably 150 m 2 / g or more. Moreover, it is preferable that the BET specific surface area of inorganic powder is 400 m < 2 > / g or less. When the BET specific surface area of the inorganic powder exceeds 400 m 2 / g, the surface activity of the particles is high and the cohesive force becomes strong, and therefore, it is not preferable because the inorganic powder is hardly uniformly dispersed in the microporous film. The average secondary particle diameter is preferably 5 μm or less in order to suppress the occurrence of pinholes in the obtained microporous film.
無機粉体の疎水化度とは、無機粉体の親水性（疎水性）を表す尺度として一般に用いられているものであり、次のようにして求めることができる。この数値が大きいほど疎水性が高く、この数値が小さいほど親水性が高いことを示す。
（１）底部に攪拌子が置かれイオン交換水が５０ｍｌ入れられた２００ｍｌビーカーに、無機粉体を０．２ｇ加え、攪拌子を回転させ、攪拌する。
（２）攪拌を続けながら、メタノールを入れたビュレットの先端を液中に沈め、メタノールを少量ずつ加える。
（３）無機粉体の全量が液中に沈むまでに要したメタノールの総添加量Ｘ（ｍｌ）を測定する。
（４）次式により、疎水化度を算出する。
疎水化度（％）＝Ｘ／（５０＋Ｘ）×１００
（５）尚、メタノールを添加し始める前に無機粉体の全量が液中に沈んだ場合、疎水化度は０％となる。
The degree of hydrophobicity of the inorganic powder is generally used as a scale representing the hydrophilicity (hydrophobicity) of the inorganic powder, and can be determined as follows. A larger value indicates higher hydrophobicity, and a smaller value indicates higher hydrophilicity.
(1) 0.2 g of inorganic powder is added to a 200 ml beaker in which a stirrer is placed at the bottom and 50 ml of ion exchange water is placed, and the stirrer is rotated and stirred.
(2) While continuing to stir, the tip of the burette containing methanol is submerged in the liquid, and methanol is added little by little.
(3) Measure the total amount X (ml) of methanol required for the total amount of inorganic powder to sink into the liquid.
(4) The degree of hydrophobicity is calculated by the following formula.
Hydrophobicity (%) = X / (50 + X) × 100
(5) If the total amount of the inorganic powder sinks in the liquid before starting to add methanol, the degree of hydrophobicity becomes 0%.
無機粉体は、（１）主にポリオレフィン系樹脂と無機粉体と可塑剤とからなる原料組成物にあって、多量に添加される可塑剤を吸着・担持し各原材料が均一に分散した状態のシート状物を得やすくするための可塑剤の担持材としての役割を有する材料であり、（２）主にポリオレフィン系樹脂と無機粉体とからなる空隙率５０体積％以上の三次元網目状構造体である微多孔性フィルムにあって、熱的に弱いポリオレフィン系樹脂の骨格を熱的に安定な無機物の骨格で支え、微多孔性フィルムの熱的寸法安定性を高める役割を有する材料であり、（３）蓄電デバイス用セパレータに適用した場合にドライアウトを抑制するための電解液を保持する液保持材としての役割を有する材料である。尚、上記（２）の役割についてもう少し具体的に述べると、無機粉体は、半製品シートである非多孔性フィルムシートから可塑剤を除去され高空隙率の三次元網目状構造体となった微多孔性フィルムシートにおいて熱的に安定な無機粉体がポリオレフィン系樹脂とともに骨格を形成していることで、可塑剤除去後のシートの寸法収縮に耐える寸法安定性や、蓄電デバイス用セパレータ適用時等の微多孔性フィルムシートの熱処理時のシートの寸法収縮や微孔閉塞に耐える寸法安定性といった役割を有する。 The inorganic powder is (1) a raw material composition mainly composed of a polyolefin resin, an inorganic powder and a plasticizer, in which a large amount of added plasticizer is adsorbed and supported and each raw material is uniformly dispersed. It is a material that has a role as a plasticizer support material for making it easy to obtain a sheet-like material, and (2) a three-dimensional network having a porosity of 50% by volume or more mainly composed of a polyolefin resin and an inorganic powder. It is a microporous film that is a structure, and is a material that supports the thermally weak polyolefin resin skeleton with a thermally stable inorganic skeleton and enhances the thermal dimensional stability of the microporous film. Yes, and (3) a material having a role as a liquid holding material for holding an electrolytic solution for suppressing dryout when applied to a separator for an electricity storage device. More specifically, the role of the above (2) will be described in more detail. The inorganic powder is a semi-finished sheet of non-porous film sheet from which the plasticizer is removed to form a high porosity three-dimensional network structure. In the microporous film sheet, the thermally stable inorganic powder forms a skeleton together with the polyolefin resin, so that dimensional stability that can withstand the dimensional shrinkage of the sheet after removal of the plasticizer and when applying a separator for electricity storage devices The film has a role of dimensional stability to withstand dimensional shrinkage and micropore blockage during heat treatment of the microporous film sheet.
可塑剤は、主に、原料組成物におけるポリオレフィン系樹脂の可塑剤としての役割と、原料組成物からなる非多孔性フィルム状の半製品シートから除去されることで微多孔性フィルム化するための開孔剤としての役割を有する材料である。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く、ステアリルアルコール等の高級アルコールは再利用時に熱劣化しやすく、フタル酸ジオクチル等のフタル酸エステル系可塑剤はホルモン撹乱物質の疑いがあるため好ましくない。 The plasticizer mainly serves as a plasticizer for the polyolefin resin in the raw material composition, and for making a microporous film by removing it from the non-porous film-like semi-finished product sheet made of the raw material composition. It is a material having a role as a pore opening agent. 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 them, mineral oil is preferable because it is easy to reuse. Higher alcohols such as stearyl alcohol are susceptible to thermal degradation during reuse, and phthalate ester plasticizers such as dioctyl phthalate are suspected of being hormone disruptors. It is not preferable.
可塑剤は、原料組成物からなる非多孔性フィルム状の半製品シートより除去されることで、半製品シートである非多孔性フィルムを微多孔性フィルム化することができるが、可塑剤の除去は、抽出溶剤を使用する方法が好ましい。抽出溶剤を使用する方法としては、抽出溶剤の槽に半製品シートを浸漬する方法が好ましい。スプレー方式やシャワー方式は溶剤のミストを生じやすく、引火の危険性があるため好ましくない。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。 By removing the plasticizer from the non-porous film-shaped semi-finished product sheet made of the raw material composition, the non-porous film that is the semi-finished product sheet can be made into a microporous film. Is preferably a method using an extraction solvent. As a method of using the extraction solvent, a method of immersing the semi-finished product sheet in the extraction solvent tank is preferable. The spray method and the shower method are not preferred because they easily cause solvent mist and there is a risk of ignition. 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.
本発明の微多孔性フィルムは、比表面積が大きく親水性が高い無機粉体を多量に含有しており、それだけでも、親水性を有するが、実質的に表面張力４８ｍＮ／ｍ以上のイオン液体のみ又は実質的に表面張力４８ｍＮ／ｍ以上のイオン液体と電解質塩のみで構成される電解液からなる蓄電デバイス用のセパレータとして、十分な電解液濡れ性を維持させるため、界面活性剤を微多孔性フィルムの基材表面（細孔内外表面）に含ませる。 The microporous film of the present invention contains a large amount of inorganic powder having a large specific surface area and high hydrophilicity, which alone has hydrophilicity, but is substantially only an ionic liquid having a surface tension of 48 mN / m or more. Alternatively, a surfactant is microporous to maintain sufficient electrolyte wettability as a separator for an electricity storage device consisting of an electrolyte composed of only an ionic liquid having a surface tension of 48 mN / m or more and an electrolyte salt. It is included in the base material surface (inside and outside surfaces of the pores) of the film.
界面活性剤を微多孔性フィルムの基材表面（細孔内外表面）に含ませる方法としては、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）、製膜され可塑剤が除去された微多孔性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、本発明の微多孔性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。しかし、可塑剤除去後の微多孔性フィルムに後処理する方法（外添法）は、界面活性剤の添加量を少なくできる点では、原料組成物中に予め添加する方法（内添法）よりも優位性があり、好ましい。界面活性剤の含有量（必要量）は、前述の通り、本発明の微多孔性フィルム中に、原料組成物中に予め添加する方法（内添法）では１〜１５質量％、より好ましくは３〜１５質量％、可塑剤除去後の微多孔性フィルムに後処理する方法（外添法）では０．５〜７質量％、より好ましくは１．５〜７質量％である。界面活性剤の含有量をこの範囲以上に増量しても、微多孔性フィルムの親水性を向上させる効果は大きく伸びず、逆に、微多孔性フィルムの空隙率を低下させて蓄電デバイス用セパレータとして内部抵抗の増大を招いたり、蓄電デバイス用セパレータとして自己放電の増大を招く。よって、界面活性剤の含有量は、本発明の微多孔性フィルム中に、原料組成物中に予め添加する方法（内添法）で１〜１０質量％、更には１〜８質量％であることがより好ましい。また、界面活性剤の含有量（必要量）が内添法と外添法とで差があるのは、可塑剤除去後の微多孔性フィルムに後処理する方法（外添法）では、原料組成物中に予め添加する方法（内添法）よりも、添加した界面活性剤を、目的とする微多孔性フィルムの基材表面（細孔内外表面）に効率的に含ませることができるためである。 As a method for including the surfactant on the substrate surface (inside and outside surfaces of the pores) of the microporous film, a method of adding the dispersion in advance to the raw material composition before film formation (internal addition method), There is a method of post-processing (external addition method) on the microporous film from which the plasticizer has been removed, but the manufacturing process can be simplified and the surfactant is soaked from the microporous film of the present invention. The method of adding in advance to the raw material composition (internal addition method) is preferable in that it is difficult to take out. However, the method of externally treating the microporous film after removal of the plasticizer (external addition method) is more than the method of adding it to the raw material composition (internal addition method) in that the amount of surfactant added can be reduced. Is preferable because of its superiority. As described above, the content (required amount) of the surfactant is 1 to 15% by mass, more preferably, in the microporous film of the present invention by the method of adding the raw material composition in advance (internal addition method). 3 to 15% by mass, and 0.5 to 7% by mass, more preferably 1.5 to 7% by mass in the method of externally treating the microporous film after removing the plasticizer (external addition method). Even if the content of the surfactant is increased beyond this range, the effect of improving the hydrophilicity of the microporous film does not greatly increase, and conversely, the porosity of the microporous film is lowered to reduce the separator for the electricity storage device. As a result, the internal resistance increases, or the self-discharge increases as a separator for an electricity storage device. Therefore, the content of the surfactant is 1 to 10% by mass, and further 1 to 8% by mass in the microporous film of the present invention by a method of adding the raw material composition in advance (internal addition method). It is more preferable. In addition, the surfactant content (required amount) is different between the internal addition method and the external addition method. In the method of post-processing the microporous film after removing the plasticizer (external addition method), the raw material Since the added surfactant can be more efficiently contained on the substrate surface (inside and outside surfaces of the pores) of the target microporous film than the method of adding in advance to the composition (internal addition method). It is.
界面活性剤としては、微多孔性フィルム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 microporous film, 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.
原料組成物又は微多孔性フィルムには、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、本発明の目的及び効果を損なわない範囲で添加（配合）又は含有させてもよい。日光の紫外線にさらされるような使用形態では、ポリオレフィン系樹脂の紫外線劣化を防止するための耐候剤を添加することが好ましい。耐候剤としては、フェノール樹脂、カーボンブラック等が使用できる。フェノール樹脂としては、有機溶剤に不溶であり、ノボラックタイプ又はレゾールタイプのもの、又はエポキシ樹脂変性フェノール樹脂等が使用できる。フェノール樹脂は、ポリオレフィン系樹脂の酸化劣化を防止する酸化防止剤としての機能や、ポリオレフィン系樹脂製微多孔性フィルム中に無機粉体を含ませたときに発揮される耐熱性向上効果を厚さ１００μｍ以下の微多孔性フィルム基材において高める機能も有する材料である。本発明の微多孔性フィルムにおける耐候剤の含有量は、０．５〜５質量％が好ましい。フェノール樹脂を前記した酸化防止機能や耐熱性向上機能のために含ませる場合は、０．２〜０．５質量％の含有量でも効果がある。 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. In a usage form such as exposure to ultraviolet rays of sunlight, it is preferable to add a weathering agent for preventing ultraviolet degradation of the polyolefin resin. A phenol resin, carbon black, etc. can be used as a weathering agent. As a phenol resin, it is insoluble in an organic solvent, and a novolac type or a resol type, or an epoxy resin-modified phenol resin can be used. Phenol resin has a function as an antioxidant that prevents oxidative degradation of polyolefin resin and a heat resistance improvement effect that is exhibited when inorganic powder is included in polyolefin resin microporous film. It is a material that also has a function of enhancing the microporous film substrate of 100 μm or less. The content of the weathering agent in the microporous film of the present invention is preferably 0.5 to 5% by mass. When a phenol resin is included for the above-described antioxidant function or heat resistance improving function, a content of 0.2 to 0.5% by mass is also effective.
本発明の微多孔性フィルムは、前述の通り、ポリオレフィン系樹脂を２０〜６０質量％と、無機粉体を４０〜８０質量％と、界面活性剤（固形分）を１〜１５質量％（原料組成物中に界面活性剤を含有する場合）又は０．５〜７質量％（原料組成物中には含有せず微多孔性フィルム中に界面活性剤を含有する場合）含む。本発明の微多孔性フィルムは、ポリオレフィン系樹脂と無機粉体が骨格材となって三次元網目状構造体（微多孔膜）を構成する基材である。ポリオレフィン系樹脂の含有量が２０質量％未満であると、ポリオレフィン系樹脂を微多孔性フィルム全体に均一に分散できなくなり、微多孔性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質量％を超える場合も、ポリオレフィン系樹脂の含有量が２０質量％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４０質量％未満であると、微多孔性フィルムの親水性（電解液濡れ性）を高める効果、微多孔性フィルムの熱的寸法安定性を高める効果、微多孔性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、微多孔性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４０質量％未満であると、可塑剤の配合量が減少するため、微多孔性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６０質量％を超える場合も、無機粉体の含有量が４０質量％未満となるため、同様の理由により不適である。よって、無機粉体の含有量は、５５〜８０質量％（ポリオレフィン系樹脂の含有量は２０〜４５質量％）、更には６０〜８０質量％（ポリオレフィン系樹脂の含有量は２０〜４０質量％）であることがより好ましい。尚、本発明の微多孔性フィルムは、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、微多孔性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。原料組成物中及び原料組成物からなる非多孔性フィルム状の半製品シート中及び微多孔性フィルム中のポリオレフィン系樹脂と無機粉体の組成比（質量比）は、２０／８０〜６０／４０である。ポリオレフィン系樹脂と無機粉体の組成比が２０／８０未満であると、原料組成物中の無機粉体の組成比が多くなりすぎ、溶融混練による押し出しがし難くなるため不適であり、６０／４０を超えると、微多孔性フィルム中の無機粉体の組成比が少なくなり、前記したような微多孔性フィルムの親水性（電解液濡れ性）を高める効果が得られ難くなるため不適である。 As described above, the microporous film of the present invention has a polyolefin resin of 20 to 60% by mass, an inorganic powder of 40 to 80% by mass, and a surfactant (solid content) of 1 to 15% by mass (raw material). In the case where a surfactant is contained in the composition) or 0.5 to 7% by mass (in the case where the surfactant is contained in the microporous film without being contained in the raw material composition). The microporous film of the present invention is a base material constituting a three-dimensional network structure (microporous film) using a polyolefin resin and inorganic powder as a skeleton material. When the content of the polyolefin resin is less than 20% by mass, 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 mass, the content of the polyolefin resin is less than 20% by mass, which is not suitable for the same reason. Further, when the content of the inorganic powder is less than 40% by mass, the effect of increasing the hydrophilicity (electrolytic solution wettability) of the microporous film, the effect of increasing the thermal dimensional stability of the microporous film, The effect of miniaturizing and complicating the pore structure of the porous film to prevent short-circuiting, the effect of retaining the electrolytic solution of the microporous film, and the like cannot be exhibited sufficiently, which is not suitable. In addition, when the content of the inorganic powder is less than 40% by mass, 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-based resin exceeds 60% by mass, the content of the inorganic powder is less than 40% by mass, which is inappropriate for the same reason. Therefore, the content of the inorganic powder is 55 to 80% by mass (the content of the polyolefin resin is 20 to 45% by mass), and further 60 to 80% by mass (the content of the polyolefin resin is 20 to 40% by mass). ) Is more preferable. The microporous film of the present invention is obtained by melting and kneading a raw material composition mainly composed of a polyolefin resin, an inorganic powder and a plasticizer and removing the plasticizer as described above. However, the constituent ratio of the polyolefin resin and the inorganic powder in the raw material composition and the constituent ratio of the polyolefin resin and the inorganic powder in the microporous film are basically the same. The composition ratio (mass ratio) between the polyolefin-based resin and the inorganic powder in the raw material composition and in the non-porous film-like semi-finished product sheet and the microporous film is 20/80 to 60/40. It is. If the composition ratio of the polyolefin-based resin and the inorganic powder is less than 20/80, the composition ratio of the inorganic powder in the raw material composition becomes too large, and it is difficult to perform extrusion by melt-kneading. If it exceeds 40, the composition ratio of the inorganic powder in the microporous film decreases, and it is difficult to obtain the effect of increasing the hydrophilicity (electrolytic solution wettability) of the microporous film as described above, which is not suitable. .
原料組成物中の可塑剤の組成比率については、前述したように、原料組成物中で無機粉体に可塑剤を吸着・担持させ原料組成物中の各原材料を均一に分散させるようにしているため、実際に使用する無機粉体の可塑剤吸収能（吸油量）、比表面積、見掛け密度等の物性に応じてその好適条件は大きく影響を受けることになるが、通常、原料組成物中の無機粉体１００質量部に対して１５０〜２５０質量部の量であることが好ましい。１５０質量部未満では、ポリオレフィン系樹脂の可塑化効果が不足し原料組成物の押出性や成形性が低下するため好ましくなく、２５０質量部を超えると、半製品シートから可塑剤を除去した後の微多孔性フィルムシートの寸法収縮が大きくなるため好ましくない。 Regarding the composition ratio of the plasticizer in the raw material composition, as described above, the plasticizer is adsorbed and supported on the inorganic powder in the raw material composition so that each raw material in the raw material composition is uniformly dispersed. Therefore, the preferred conditions will be greatly affected by the physical properties such as the plasticizer absorption capacity (oil absorption amount), specific surface area, and apparent density of the inorganic powder actually used, but usually in the raw material composition The amount is preferably 150 to 250 parts by mass with respect to 100 parts by mass of the inorganic powder. If it is less than 150 parts by mass, the plasticizing effect of the polyolefin resin is insufficient and the extrudability and moldability of the raw material composition are reduced, and if it exceeds 250 parts by mass, the plasticizer is removed from the semi-finished sheet. This is not preferable because the dimensional shrinkage of the microporous film sheet increases.
半製品シートである非多孔性フィルム状シートからの可塑剤の除去は、通常、実質的にその全量を除去すればよいが、必要に応じ、意図的にその一部のみを除去するようにしてもよい。可塑剤の役割は、前述したように、主に、原料組成物におけるポリオレフィン系樹脂の可塑剤としての役割と、半製品シートから除去されることで微多孔性フィルム化するための開孔剤としての役割であるので、完成品である微多孔性フィルムシートにおいては役割を有していないと言え、半製品シートからの可塑剤の除去は、その全量を除去すればよいと言える。よって、通常は、半製品シートからの可塑剤の除去は実質的にその全量を除去するようにし、微多孔性フィルムシート中の可塑剤の残留量（含有量）は実質的にゼロである１質量％未満とすればよい。しかし、微多孔性フィルムシートの空隙率を調整するために、半製品シートからの可塑剤の除去をその一部に留め意図的に可塑剤の一部をシート中に残留させるようにしてもよい。半製品シートから可塑剤の一部のみを除去したときの微多孔性フィルムシート中の可塑剤の残留量は、可塑剤を抽出除去する際の抽出条件を操作することで任意に設定が可能であり、容易に目的の可塑剤含有量の微多孔性フィルムシートを製造することができる。微多孔性フィルムシートの可塑剤含有量を調整することで、微多孔性フィルムシートの空隙率を調整できる。微多孔性フィルムシートの空隙率を調整するための微多孔性フィルムシート中の可塑剤の残留量（含有量）は、通常１〜２０質量％とするのが好ましい。 The removal of the plasticizer from the non-porous film-like sheet which is a semi-finished product sheet is usually sufficient to remove substantially the entire amount, but if necessary, only a part of it is intentionally removed. Also good. As described above, the role of the plasticizer is mainly as a plasticizer of the polyolefin resin in the raw material composition and as a pore opening agent for forming a microporous film by being removed from the semi-finished product sheet. Therefore, it can be said that the finished microporous film sheet has no role, and it can be said that the removal of the plasticizer from the semi-finished sheet may be performed by removing the entire amount. Therefore, usually, removal of the plasticizer from the semi-finished sheet is made to remove substantially the whole amount, and the residual amount (content) of the plasticizer in the microporous film sheet is substantially zero. What is necessary is just to set it as less than mass%. However, in order to adjust the porosity of the microporous film sheet, the removal of the plasticizer from the semi-finished product sheet is partly retained, and a part of the plasticizer may be intentionally left in the sheet. . The residual amount of plasticizer in the microporous film sheet when only a part of the plasticizer is removed from the semi-finished product sheet can be arbitrarily set by manipulating the extraction conditions for extracting and removing the plasticizer. Yes, it is possible to easily produce a microporous film sheet having a desired plasticizer content. By adjusting the plasticizer content of the microporous film sheet, the porosity of the microporous film sheet can be adjusted. The residual amount (content) of the plasticizer in the microporous film sheet for adjusting the porosity of the microporous film sheet is usually preferably 1 to 20% by mass.
原料組成物の溶融混練の方法は特に限定されないが、通常、二軸押出機中で均一に混練することにより行う。溶融混練押出温度は、２００〜２４０℃とすることが好ましい。２５０℃を超える温度では、樹脂の熱劣化が起こり易くなるとともに、可塑剤の引火点に接近するため好ましくない。尚、可塑剤は、溶融混練の前にその全量を他の原材料と共に混合しておくことが望ましいが、一部の量だけを溶融混練中に別途添加するようにしてもよい。 The method of melt kneading the raw material composition is not particularly limited, but it is usually carried out by uniformly kneading in a twin screw extruder. The melt-kneading extrusion temperature is preferably 200 to 240 ° C. A temperature exceeding 250 ° C. is not preferable because thermal deterioration of the resin is likely to occur and the flash point of the plasticizer is approached. The plasticizer is desirably mixed with the other raw materials before the melt kneading, but only a part of the plasticizer may be added separately during the melt kneading.
以上のように、本発明の微多孔性フィルムの製造方法は、ポリオレフィン系樹脂と無機粉体と可塑剤とを主構成とした原料組成物を溶融混練して押出成形等によりシート状に製膜し圧延及び／又は延伸による薄肉化成形して非多孔性フィルム（半製品シート）を得る工程、非多孔性フィルムから抽出溶剤による抽出除去等により可塑剤を除去して微多孔性フィルムを得る工程、微多孔性フィルム中の溶剤を乾燥除去する工程を含むものである。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、界面活性剤と必要に応じ他の添加剤を加えた原材料をヘンシェルミキサー又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、目的の微多孔性フィルムが得られる。尚、界面活性剤の添加は、前述したように、原料組成物中に予め添加するようにしてもよいし、可塑剤除去後の微多孔性フィルムシートに後処理するようにしてもよい。尚、延伸による薄肉化成形は、可塑剤除去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。また、薄肉化成形は、通常、まず、例えば押出機より押し出した直後の高温のシート状物をカレンダーロール間に通して圧延による薄肉化成形を行い、その後必要に応じて更に圧延及び／又は延伸による薄肉化成形を行う。薄肉化成形は、微多孔性フィルムの要求される厚さに応じて、様々な手法を取ることが可能であり、例えば、前記したようなロール圧延による薄肉化成形を多段にて行ったり、ロール圧延による薄肉化成形後に延伸による薄肉化成形を行うことで、より薄肉化への対応が可能である。これにより、完成品である微多孔性フィルムの厚さは、１０〜１００μｍの範囲で製造可能である。 As described above, the method for producing a microporous film of the present invention comprises forming a sheet composition by extrusion molding or the like after melting and kneading a raw material composition mainly composed of a polyolefin resin, an inorganic powder, and a plasticizer. A step of obtaining a non-porous film (semi-finished product sheet) by thinning molding by rolling and / or stretching, a step of obtaining a microporous film by removing a plasticizer from the non-porous film by extraction removal with an extraction solvent, etc. And a step of drying and removing the solvent in the microporous film. 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 surfactant and other additives as necessary to a polyolefin resin, inorganic powder, and plasticizer is agitated and mixed by a mixer such as a Henschel mixer or a Laedige mixer, and a raw material mixture is obtained. obtain. 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 dipped in a suitable solvent (for example, n-hexane), and the plasticizer is extracted and removed, dried, and heat-treated as necessary to obtain the desired microporous film. As described above, the surfactant may be added in advance to the raw material composition, or may be post-treated on the microporous film sheet after the plasticizer is removed. The thinning molding by stretching may be performed in the pre-process of removing the plasticizer, in the post-process, or in the previous and subsequent processes. Further, in the thinning molding, usually, for example, a high-temperature sheet-like material immediately after being extruded from an extruder is passed between calender rolls to perform thinning molding by rolling, and then further rolling and / or stretching as necessary. Perform thin-walled molding. Thin-walled molding can take various methods depending on the required thickness of the microporous film. For example, thin-walled molding by roll rolling as described above can be performed in multiple stages, By performing thinning molding by stretching after thinning molding by rolling, it is possible to cope with thinning. Thereby, the thickness of the microporous film which is a finished product can be manufactured in the range of 10 to 100 μm.
原料組成物や原料組成物からなる非多孔性フィルム状の半製品シートは、実質的に、ポリオレフィン系樹脂と無機粉体と可塑剤と界面活性剤の４者の組成物（界面活性剤を後処理のみにより添加する場合は界面活性剤を除く３者の組成物）であればよく、必要に応じて、前記したような耐候剤や酸化防止剤等の各種添加剤を添加することもできる。 A non-porous film-like semi-finished product sheet made of a raw material composition or a raw material composition is substantially composed of a four-component composition (polyolefin resin, inorganic powder, plasticizer, and surfactant). When it is added only by treatment, it may be a three-part composition excluding the surfactant), and various additives such as weathering agents and antioxidants as described above can be added as necessary.
完成品である微多孔性フィルムは、実質的に、ポリオレフィン系樹脂と無機粉体と界面活性剤の３者の組成物であればよいが、前記したような耐候剤や酸化防止剤等の各種添加剤、更には、前記したように、用途によっては空隙率を調整するために可塑剤を１〜２０質量％含有させるようにしてもよい。 The microporous film that is a finished product may be substantially a three-component composition of a polyolefin resin, an inorganic powder, and a surfactant, but various kinds of weathering agents and antioxidants as described above. In addition, as described above, 1 to 20% by mass of a plasticizer may be contained in order to adjust the porosity depending on the application.
本発明のセパレータは、前述の通り、電解液が実質的にイオン液体のみ又は実質的にイオン液体と電解質塩のみで構成される蓄電デバイスに好適に使用できるものであるが、前記蓄電デバイスとしては、例えば、既存の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等の他、現在研究が進められている次世代の蓄電デバイスにも同様の電解液を適用する動きがあり、これら幅広い用途への適用が考えられる。
尚、本発明において、前記イオン液体としては、前述したように、融点が１００℃以下であり、特に、表面張力（２５℃、懸滴法、協和界面科学社製DropMaster500にて測定）が４８ｍＮ／ｍ以上、更には５３ｍＮ／ｍ以上であるものを照準とする。また、前記電解質塩は、リチウム塩などを指す。
As described above, the separator of the present invention can be suitably used for an electricity storage device in which the electrolyte is substantially composed of only the ionic liquid or substantially only the ionic liquid and the electrolyte salt. For example, in addition to existing lithium ion secondary batteries, polymer lithium secondary batteries, electric double layer capacitors, lithium ion capacitors, etc., the same electrolyte solution is also applied to next-generation power storage devices that are currently being researched There is a movement, and it can be applied to these wide applications.
In the present invention, as described above, the ionic liquid has a melting point of 100 ° C. or less, and particularly has a surface tension (25 ° C., hanging drop method, measured with DropMaster500 manufactured by Kyowa Interface Science Co., Ltd.) of 48 mN / Aiming at m or more, further 53 mN / m or more. The electrolyte salt refers to a lithium salt or the like.
次に、本発明の実施例について、比較例とともに詳細に説明する。
（実施例１）
ポリオレフィン系樹脂として重量平均分子量１５０万のポリエチレン樹脂粉体１００部（質量部、以下同じ）と、親水性無機粉体として疎水化度０％でＢＥＴ比表面積２００ｍ２／ｇで平均二次粒子径２μｍのシリカ微粉体２００部と、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４００部と、界面活性剤としてジアルキルスルホコハク酸ナトリウム塩３部とをレーディゲミキサーにて混合した原料混合物を、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、滑らかな表面を有する一対の成形ロール間を通して圧延し厚さ１５０μｍのシートとし、更に、加温状態にてＭＤ方向に延伸倍率３倍の一軸延伸を行い厚さ５０μｍのシートとした。次に、該シートをｎ−ヘキサン中に浸漬し前記シート中のパラフィン系オイルの全量を抽出除去し、乾燥して、ポリエチレン樹脂３３．０質量％とシリカ微粉体６６．０質量％と界面活性剤１．０質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率７２％の微多孔性フィルムを得た。これを実施例１のセパレータとした。
Next, examples of the present invention will be described in detail together with comparative examples.
Example 1
100 parts of polyethylene resin powder having a weight average molecular weight of 1,500,000 (parts by mass) as a polyolefin-based resin, and an average secondary particle diameter at a BET specific surface area of 200 m 2 / g with a hydrophobization degree of 0% as a hydrophilic inorganic powder A raw material mixture obtained by mixing 200 parts of 2 μm fine silica powder, 400 parts of paraffinic oil which is a kind of mineral oil as a plasticizer, and 3 parts of dialkylsulfosuccinic acid sodium salt as a surfactant with a Ladige mixer, It is put into a twin-screw extruder with a T-die attached at the tip, extruded into a sheet while heating, melting and kneading, rolled through a pair of forming rolls with a smooth surface, and made into a sheet with a thickness of 150 μm. Was uniaxially stretched 3 times in the MD direction to obtain a sheet having a thickness of 50 μm. Next, the sheet is immersed in n-hexane to extract and remove the total amount of paraffinic oil in the sheet, followed by drying to obtain 33.0% by mass of polyethylene resin, 66.0% by mass of silica fine powder, and surface activity. A microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 72% composed of 1.0% by mass of the agent was obtained. This was used as the separator of Example 1.
（実施例２）
実施例１において、界面活性剤の配合量を１０部とした以外は、同様の方法により、ポリエチレン樹脂３２．３質量％とシリカ微粉体６４．５質量％と界面活性剤３．２質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率７１％の微多孔性フィルムを得た。これを実施例２のセパレータとした。
(Example 2)
In Example 1, except that the compounding amount of the surfactant was 10 parts, the same method was used to obtain 32.3% by mass of polyethylene resin, 64.5% by mass of silica fine powder, and 3.2% by mass of surfactant. A microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 71% was obtained. This was used as the separator of Example 2.
（実施例３）
実施例１において、界面活性剤の配合量を１５部とした以外は、同様の方法により、ポリエチレン樹脂３１．７質量％とシリカ微粉体６３．５質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率７０％の微多孔性フィルムを得た。これを実施例３のセパレータとした。
(Example 3)
In Example 1, except that the blending amount of the surfactant was 15 parts, by the same method, the polyethylene resin was 31.7% by mass, the silica fine powder was 63.5% by mass, and the surfactant was 4.8% by mass. A microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 70% was obtained. This was used as the separator of Example 3.
（実施例４）
実施例１において、界面活性剤の配合量を５２部とした以外は、同様の方法により、ポリエチレン樹脂２８．４質量％とシリカ微粉体５６．８質量％と界面活性剤１４．８質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率６３％の微多孔性フィルムを得た。これを実施例４のセパレータとした。
Example 4
In Example 1, except that the amount of the surfactant was changed to 52 parts, the same procedure was followed to obtain 28.4% by mass of the polyethylene resin, 56.8% by mass of the fine silica powder, and 14.8% by mass of the surfactant. A microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 63% was obtained. This was used as the separator of Example 4.
（実施例５）
ポリオレフィン系樹脂として重量平均分子量１５０万のポリエチレン樹脂粉体１００部と、親水性無機粉体として疎水化度０％でＢＥＴ比表面積２００ｍ２／ｇで平均二次粒子径２μｍのシリカ微粉体２００部と、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４００部とをレーディゲミキサーにて混合した原料混合物を、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、滑らかな表面を有する一対の成形ロール間を通して圧延し厚さ１５０μｍのシートとし、更に、加温状態にてＭＤ方向に延伸倍率３倍の一軸延伸を行い厚さ５０μｍのシートとした。次に、該シートをｎ−ヘキサン中に浸漬し前記シート中のパラフィン系オイルの全量を抽出除去し、乾燥して、微多孔性シートとした。次に、界面活性剤としてジアルキルスルホコハク酸ナトリウム塩をエタノールに溶解させ均一分散させた溶液を、完成シート中の固形分付着量が３．２質量となるよう液濃度と含浸量を調整した上で、前記シートに均一に含浸させ、乾燥して、ポリエチレン樹脂３２．３質量％とシリカ微粉体６４．５質量％と界面活性剤３．２質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率７０％の微多孔性フィルム（完成シート）を得た。これを実施例５のセパレータとした。
(Example 5)
100 parts of a polyethylene resin powder having a weight average molecular weight of 1,500,000 as a polyolefin resin, and 200 parts of a silica fine powder having a hydrophobicity of 0%, a BET specific surface area of 200 m 2 / g and an average secondary particle diameter of 2 μm as a hydrophilic inorganic powder. Then, a raw material mixture obtained by mixing 400 parts of paraffinic oil, which is a kind of mineral oil as a plasticizer, with a Ladige mixer is introduced into a twin-screw extruder having a T die attached to the tip, and heated, melted and kneaded. Extruded into a sheet, rolled through a pair of forming rolls having a smooth surface to form a sheet having a thickness of 150 μm, and further uniaxially stretching in the MD direction at a stretching ratio of 3 times in a heated state to form a sheet having a thickness of 50 μm did. Next, the sheet was immersed in n-hexane to extract and remove the entire amount of paraffinic oil in the sheet, and dried to obtain a microporous sheet. Next, after adjusting the liquid concentration and the amount of impregnation of a solution obtained by dissolving dialkylsulfosuccinic acid sodium salt in ethanol as a surfactant and uniformly dispersing it in ethanol, the solid content adhesion amount in the finished sheet is 3.2 mass. The sheet is uniformly impregnated and dried to a thickness of 50 μm and an average pore size of 0. 3% comprising polyethylene resin 32.3% by mass, silica fine powder 64.5% by mass and surfactant 3.2% by mass. A microporous film (finished sheet) having a thickness of 1 μm and a porosity of 70% was obtained. This was used as the separator of Example 5.
（比較例１）
実施例１において、界面活性剤の配合量を７５部とした以外は、同様の方法により、ポリエチレン樹脂２６．７質量％とシリカ微粉体５３．３質量％と界面活性剤２０．０質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率６０％の微多孔性フィルムを得た。これを比較例１のセパレータとした。
(Comparative Example 1)
In Example 1, except that the blending amount of the surfactant was 75 parts, the same procedure was followed to obtain 26.7% by weight of polyethylene resin, 53.3% by weight of fine silica powder, and 20.0% by weight of surfactant. A microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 60% was obtained. This was used as the separator of Comparative Example 1.
（比較例２）
実施例１において、界面活性剤を配合しなかった以外は、同様の方法により、ポリエチレン樹脂３３．３質量％とシリカ微粉体６６．７質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率７２％の微多孔性フィルムを得た。これを比較例２のセパレータとした。
(Comparative Example 2)
In Example 1, except that the surfactant was not blended, a thickness of 50 μm composed of 33.3% by mass of polyethylene resin and 66.7% by mass of silica fine powder was obtained in the same manner, and the average pore diameter was 0.1 μm. A microporous film having a porosity of 72% was obtained. This was used as the separator of Comparative Example 2.
（実施例６）
実施例１において、各原材料の配合量を、ポリオレフィン系樹脂１００部と親水性無機粉体７５部と可塑剤１５０部と界面活性剤９部とした以外は、同様の方法により、ポリエチレン樹脂５４．４質量％とシリカ微粉体４０．８質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．０５μｍ、空隙率５０％の微多孔性フィルムを得た。これを実施例６のセパレータとした。
(Example 6)
According to the same method as in Example 1, except that the amount of each raw material was changed to 100 parts polyolefin resin, 75 parts hydrophilic inorganic powder, 150 parts plasticizer, and 9 parts surfactant, polyethylene resin 54. A microporous film having a thickness of 50 μm, an average pore diameter of 0.05 μm, and a porosity of 50% composed of 4% by mass, 40.8% by mass of silica fine powder and 4.8% by mass of a surfactant was obtained. This was used as the separator of Example 6.
（実施例７）
実施例１において、各原材料の配合量を、ポリオレフィン系樹脂１００部と親水性無機粉体３７５部と可塑剤７５０部と界面活性剤２４部とした以外は、同様の方法により、ポリエチレン樹脂２０．０質量％とシリカ微粉体７５．２質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．２μｍ、空隙率８０％の微多孔性フィルムを得た。これを実施例７のセパレータとした。
(Example 7)
According to the same method as in Example 1, except that the amount of each raw material was changed to 100 parts of a polyolefin resin, 375 parts of a hydrophilic inorganic powder, 750 parts of a plasticizer, and 24 parts of a surfactant. A microporous film having a thickness of 50 μm, an average pore diameter of 0.2 μm, and a porosity of 80% composed of 0% by mass, silica fine powder 75.2% by mass and surfactant 4.8% by mass was obtained. This was used as the separator of Example 7.
（比較例３）
実施例１において、各原材料の配合量を、ポリオレフィン系樹脂１００部と親水性無機粉体３０部と可塑剤７０部と界面活性剤６．５部とした以外は、同様の方法により、ポリエチレン樹脂７３．３質量％とシリカ微粉体２２．０質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．０１μｍ、空隙率２０％の微多孔性フィルムを得た。これを比較例３のセパレータとした。
(Comparative Example 3)
In Example 1, a polyethylene resin was obtained in the same manner except that the amount of each raw material was 100 parts of polyolefin resin, 30 parts of hydrophilic inorganic powder, 70 parts of plasticizer, and 6.5 parts of surfactant. A microporous film having a thickness of 50 μm, an average pore size of 0.01 μm, and a porosity of 20% composed of 73.3% by mass, silica fine powder 22.0% by mass and surfactant 4.8% by mass was obtained. This was used as the separator of Comparative Example 3.
（比較例４）
ポリオレフィン系樹脂として重量平均分子量１５０万のポリエチレン樹脂粉体１００部と、親水性無機粉体として疎水化度０％でＢＥＴ比表面積９０ｍ２／ｇで平均二次粒子径２μｍのシリカ微粉体２００部と、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１５０部と、界面活性剤としてジアルキルスルホコハク酸ナトリウム塩１５部とをレーディゲミキサーにて混合した原料混合物と、前記パラフィン系オイル２５０部を、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、滑らかな表面を有する一対の成形ロール間を通して圧延し厚さ１５０μｍのシートとし、更に、加温状態にてＭＤ方向に延伸倍率３倍の一軸延伸を行い厚さ５０μｍのシートとした。次に、該シートをｎ−ヘキサン中に浸漬し前記シート中のパラフィン系オイルの全量を抽出除去し、乾燥して、ポリエチレン樹脂３１．７質量％とシリカ微粉体６３．５質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率４５％の微多孔性フィルムを得た。これを比較例４のセパレータとした。
(Comparative Example 4)
100 parts of polyethylene resin powder having a weight average molecular weight of 1,500,000 as a polyolefin-based resin, and 200 parts of silica fine powder having a hydrophobicity of 0%, a BET specific surface area of 90 m 2 / g and an average secondary particle diameter of 2 μm as a hydrophilic inorganic powder. And 150 parts of a paraffinic oil which is a kind of mineral oil as a plasticizer and 15 parts of a dialkylsulfosuccinic acid sodium salt as a surfactant in a Ladige mixer, and 250 parts of the paraffinic oil , Put into a twin-screw extruder with a T-die attached at the tip, extrude into a sheet while heating and melting and kneading, roll through a pair of forming rolls with a smooth surface to form a 150 μm thick sheet, In a warm state, the sheet was uniaxially stretched 3 times in the MD direction to obtain a sheet having a thickness of 50 μm. Next, the sheet is immersed in n-hexane to extract and remove the total amount of paraffinic oil in the sheet, and dried to obtain 31.7% by mass of polyethylene resin and 63.5% by mass of silica fine powder, and surface activity. A microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 45% composed of 4.8% by mass of the agent was obtained. This was used as the separator of Comparative Example 4.
（実施例８）
ポリオレフィン系樹脂として重量平均分子量１５０万のポリエチレン樹脂粉体１００部と、親水性無機粉体として疎水化度０％でＢＥＴ比表面積１５０ｍ２／ｇで平均二次粒子径２μｍのシリカ微粉体２００部と、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２５０部と、界面活性剤としてジアルキルスルホコハク酸ナトリウム塩１５部とをレーディゲミキサーにて混合した原料混合物と、前記パラフィン系オイル１５０部を、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、滑らかな表面を有する一対の成形ロール間を通して圧延し厚さ１５０μｍのシートとし、更に、加温状態にてＭＤ方向に延伸倍率３倍の一軸延伸を行い厚さ５０μｍのシートとした。次に、該シートをｎ−ヘキサン中に浸漬し前記シート中のパラフィン系オイルの全量を抽出除去し、乾燥して、ポリエチレン樹脂３１．７質量％とシリカ微粉体６３．５質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率６５％の微多孔性フィルムを得た。これを実施例８のセパレータとした。
(Example 8)
100 parts of polyethylene resin powder having a weight average molecular weight of 1,500,000 as a polyolefin resin, and 200 parts of silica fine powder having a hydrophobicity of 0%, a BET specific surface area of 150 m 2 / g and an average secondary particle diameter of 2 μm as a hydrophilic inorganic powder. A raw material mixture obtained by mixing 250 parts of a paraffinic oil which is a kind of mineral oil as a plasticizer, and 15 parts of a dialkylsulfosuccinic acid sodium salt as a surfactant with a Ladige mixer, and 150 parts of the paraffinic oil , Put into a twin-screw extruder with a T-die attached at the tip, extrude into a sheet while heating and melting and kneading, roll through a pair of forming rolls with a smooth surface to form a 150 μm thick sheet, In a warm state, the sheet was uniaxially stretched 3 times in the MD direction to obtain a sheet having a thickness of 50 μm. Next, the sheet is immersed in n-hexane to extract and remove the total amount of paraffinic oil in the sheet, and dried to obtain 31.7% by mass of polyethylene resin and 63.5% by mass of silica fine powder, and surface activity. A microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 65% composed of 4.8% by mass of the agent was obtained. This was used as the separator of Example 8.
（実施例９）
実施例３において、無機粉体として疎水化度２％でＢＥＴ比表面積２００ｍ２／ｇで平均二次粒子径２μｍのシリカ微粉体を用いた以外は、同様の方法により、ポリエチレン樹脂３１．７質量％とシリカ微粉体６３．５質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率７０％の微多孔性フィルムを得た。これを実施例９のセパレータとした。
Example 9
In Example 3, 31.7 mass of polyethylene resin was obtained in the same manner except that silica fine powder having a hydrophobicity of 2%, a BET specific surface area of 200 m 2 / g and an average secondary particle diameter of 2 μm was used as the inorganic powder. %, 63.5% by mass of silica fine powder, and 4.8% by mass of surfactant, a microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 70% was obtained. This was used as the separator of Example 9.
（実施例１０）
実施例３において、無機粉体として疎水化度５％でＢＥＴ比表面積２００ｍ２／ｇで平均二次粒子径２μｍのシリカ微粉体を用いた以外は、同様の方法により、ポリエチレン樹脂３１．７質量％とシリカ微粉体６３．５質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率７０％の微多孔性フィルムを得た。これを実施例１０のセパレータとした。
(Example 10)
In Example 3, 31.7 mass of polyethylene resin was obtained in the same manner except that silica fine powder having a hydrophobicity of 5%, a BET specific surface area of 200 m 2 / g and an average secondary particle diameter of 2 μm was used as the inorganic powder. %, 63.5% by mass of silica fine powder, and 4.8% by mass of surfactant, a microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 70% was obtained. This was used as the separator of Example 10.
（比較例５）
実施例３において、無機粉体として疎水化度１０％でＢＥＴ比表面積２００ｍ２／ｇで平均二次粒子径２μｍのシリカ微粉体を用いた以外は、同様の方法により、ポリエチレン樹脂３１．７質量％とシリカ微粉体６３．５質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率７０％の微多孔性フィルムを得た。これを比較例５のセパレータとした。
(Comparative Example 5)
In Example 3, 31.7 mass of polyethylene resin was obtained in the same manner except that silica fine powder having a hydrophobicity of 10%, a BET specific surface area of 200 m 2 / g and an average secondary particle diameter of 2 μm was used as the inorganic powder. %, 63.5% by mass of silica fine powder, and 4.8% by mass of surfactant, a microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 70% was obtained. This was used as the separator of Comparative Example 5.
（比較例６）
実施例３において、無機粉体として疎水化度５０％でＢＥＴ比表面積２００ｍ２／ｇで平均二次粒子径２μｍのシリカ微粉体を用いた以外は、同様の方法により、ポリエチレン樹脂３１．７質量％とシリカ微粉体６３．５質量％と界面活性剤４．８質量％で構成される厚さ５０μｍ、平均孔径０．１μｍ、空隙率７０％の微多孔性フィルムを得た。これを比較例６のセパレータとした。
(Comparative Example 6)
In Example 3, 31.7 mass of polyethylene resin was obtained in the same manner except that silica fine powder having a hydrophobicity of 50%, a BET specific surface area of 200 m 2 / g and an average secondary particle diameter of 2 μm was used as the inorganic powder. %, 63.5% by mass of silica fine powder, and 4.8% by mass of surfactant, a microporous film having a thickness of 50 μm, an average pore diameter of 0.1 μm, and a porosity of 70% was obtained. This was used as the separator of Comparative Example 6.
次に、上記にて得られた実施例１〜１０、比較例１〜６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。
〈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。
〈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。
〈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。
〈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。
〈突刺強度〉
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。
〈親水性〉
セパレータを２ｃｍ×２ｃｍ角に切り取った試験片を、常温にて、水を注入したシャーレの水面に浮かべたのち、試験片に水が浸透し、試験片が半透明になるまでの時間を測定し、親水性（秒）とした。
〈濡れ保持性〉
セパレータを３０ｍｍ×３０ｍｍ角に切り取った試験片に重りを付けて２００ｍｌの水中に浸漬し、７５℃の恒温槽内で２４時間放置後、試験片を８０℃にて乾燥した。続いて、試験片を、常温にて、イオン液体の１種である１−エチル-３−メチルイミダゾリウム テトラフルオロボレート（ＥＭＩＢＦ４）（融点約１５℃、表面張力約５４ｍＮ／ｍ（２５℃、懸滴法、協和界面科学社製DropMaster500にて測定））の液面に浮かべたのち、試験片に液が浸透し、試験片が半透明になるまでの時間を測定し、濡れ保持性（秒）とした。
〈蓄電デバイスの作製〉
ＢＥＴ比表面積１５００ｍ２／ｇの活性炭、カーボンブラック、ポリテトラフルオロエチレン樹脂を混練して、厚さ０．２ｍｍのシート状物とし、これを１０ｃｍ×１０ｃｍ角に切断してアルミニウム箔を導電性接着剤で接着させて電極とし、正極及び負極の双方に使用した。前記電極間にセパレータを挟み込み、電解液として、イオン液体の１種である１−エチル-３−メチルイミダゾリウム テトラフルオロボレート（ＥＭＩＢＦ４）（融点約１５℃、表面張力約５４ｍＮ／ｍ（２５℃、懸滴法、協和界面科学社製DropMaster500にて測定））を含浸させ、電気二重層キャパシタの試験用セルを作製した。
〈内部抵抗比率〉
前記試験用セルに、２５℃、電圧２．５Ｖの直流電圧を２時間かけて充電後、１ｋＨｚのＬＣＲメータで内部抵抗を測定した。尚、表１には、実施例３の値を１００とした相対値で表した。
〈電圧保持率〉
前記試験用セルの初期電圧（Ｖ０）と、２５℃、電圧２．５Ｖの直流電圧を２時間かけて充電後に５００時間放置後の電圧（Ｖ１）を測定し、次式により電圧保持率を算出した。
電圧保持率（％）＝(Ｖ１／Ｖ０)×１００
Next, various characteristics evaluation was performed by the following method about each separator of Examples 1-10 obtained above and Comparative Examples 1-6. The results are shown in Table 1.
<thickness>
Measurement was made with a dial thickness gauge having a 0.001 mm scale, and five points were measured in the width direction, and the average was taken as the value.
<Average pore diameter>
It measured by the mercury intrusion method (JISR1655) and calculated | required the average hole diameter.
<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.
<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.
<Hydrophilicity>
After floating a test piece with a 2 cm x 2 cm square separator on the surface of a petri dish into which water has been injected at room temperature, measure the time until water penetrates the test piece and the test piece becomes translucent. , Hydrophilic (seconds).
<Wet retention>
A test piece obtained by cutting the separator into 30 mm × 30 mm squares was weighted and immersed in 200 ml of water, left in a thermostatic bath at 75 ° C. for 24 hours, and then the test piece was dried at 80 ° C. Subsequently, at room temperature, the test piece was 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF 4 ) (melting point: about 15 ° C., surface tension: about 54 mN / m (25 ° C. The suspension drop method (measured with the DropMaster500 manufactured by Kyowa Interface Science Co., Ltd.)) is measured on the liquid surface, the time it takes for the liquid to penetrate the test piece and the test piece becomes translucent is measured, and wettability (seconds) ).
<Production of electricity storage device>
KET activated carbon with a BET specific surface area of 1500 m 2 / g, carbon black, and polytetrafluoroethylene resin are kneaded to form a sheet having a thickness of 0.2 mm, and this is cut into 10 cm × 10 cm square to electrically bond the aluminum foil. It was made to adhere | attach with an agent and it was set as the electrode, and it used for both the positive electrode and the negative electrode. A separator is sandwiched between the electrodes, and 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIBF 4 ) (melting point: about 15 ° C., surface tension: about 54 mN / m (25 ° C.), which is one of ionic liquids, as an electrolytic solution. ), Impregnated with the hanging drop method, and DropMaster500 manufactured by Kyowa Interface Science Co., Ltd.)) to impregnate an electric double layer capacitor test cell.
<Internal resistance ratio>
The test cell was charged with a DC voltage of 25 V at a voltage of 2.5 V over 2 hours, and then the internal resistance was measured with a 1 kHz LCR meter. In Table 1, relative values with the value of Example 3 as 100 are shown.
<Voltage holding ratio>
The initial voltage (V 0 ) of the test cell and a voltage (V 1 ) after charging for 500 hours after charging a DC voltage of 25 ° C. and a voltage of 2.5 V over 2 hours were measured, and the voltage holding ratio was Was calculated.
Voltage holding ratio (%) = (V 1 / V 0 ) × 100
表１の結果から以下のことが分かった。
（１）実施例１〜４のセパレータは、ポリオレフィン系樹脂が２８．４〜３３．０質量％で構成される微多孔性フィルムであって、無機粉体として、ＢＥＴ比表面積が２００ｍ２／ｇで疎水化度が０％の無機粉体を選択し、５６．８〜６６．０質量％の量を含ませた上で、界面活性剤を１．０〜１４．８質量％（内添法）含ませるようにしたことにより、厚さが５０μｍ、平均孔径が０．１μｍ、空隙率が６３〜７２％となり、機械的強度も引張強さ（ＭＤ）が２７〜３０Ｎ／ｍｍ２、突刺強度が１．８〜２Ｎとなり、親水性が１〜１０秒と良好で、濡れ保持性も１０〜４０秒と良好となった。また、空隙率が６３〜７２％とある程度高く、親水性が１〜１０秒とある程度良好であったことから、キャパシタ特性の内部抵抗比率は１００〜１３０％と良好で、また、空隙率が６３〜７２％であり、平均孔径が０．１μｍであったことから、自己放電もある程度抑えられキャパシタ特性の電圧保持率も７７〜８２％と良好であった。また、キャパシタ特性の内部抵抗比率が１００〜１３０％と良好で、濡れ保持性も１０〜４０秒と良好であったことから、キャパシタ特性において、当初の電解液濡れ性（電解液保持性）が良好であるとともに、キャパシタの使用に伴う時間経過後も良好な電解液濡れ性（電解液保持性）を維持できることが推測される。
（２）中でも、界面活性剤の含有量を３質量％以上の３．２〜１４．８質量％とした実施例２〜４のセパレータでは、親水性が１〜２秒と特に良好であり、濡れ保持性も１０秒と良好であった。
（３）中でも、界面活性剤の含有量を３質量％以上８質量％以下の３．２〜４．８質量％とした実施例２〜３のセパレータでは、空隙率が７０〜７１％と良好で、機械的強度も引張強さ（ＭＤ）が３０Ｎ／ｍｍ２、突刺強度が２Ｎと良好で、親水性も１〜２秒と良好で、濡れ保持性も１０秒と良好で、キャパシタ特性の内部抵抗比率も１００％と良好で、キャパシタ特性の電圧保持率も８１％と良好であった。
（４）実施例１〜４のセパレータに対し、界面活性剤の含有量を１５質量％超えの２０．０質量％と多くした比較例１のセパレータでは、親水性が１秒と良好で、濡れ保持性も１０秒と良好であったが、空隙率が６０％と低くなりまた過剰の界面活性剤が微多孔性フィルムの孔経路を阻害したためキャパシタ特性の内部抵抗比率が２００％と高くなり、また過剰の界面活性剤による自己放電の増大により電圧保持率が５８％と低くなり、十分なキャパシタ性能を確保できない。
（５）実施例３のセパレータに対し、界面活性剤の含有量を４．８質量％と変えず無機粉体の含有量を４０．８質量％と少なくしポリオレフィン系樹脂の含有量を５４．３質量％と多くした実施例６のセパレータでは、機械的強度は引張強さ（ＭＤ）が４５Ｎ／ｍｍ２、突刺強度が３Ｎと、何れも約５０％向上したものの、親水性が５秒と低くなり、空隙率も５０％と低くなったことから、キャパシタ特性の内部抵抗比率が１５０％と高くなり（悪化し）、また濡れ保持性も５０秒と低くなった（悪化した）。また、空隙率が５０％と低くなり、平均孔径が０．０５μｍと小さくなったことから、自己放電が抑えられキャパシタ特性の電圧保持率は８５％と高くなった（良化した）。
（６）実施例３のセパレータに対し、界面活性剤の含有量を４．８質量％と変えず無機粉体の含有量を７５．２質量％と多くしポリオレフィン系樹脂の含有量を２０．０質量％と少なくした実施例７のセパレータでは、親水性が１秒と良好で、空隙率が８０％と高くなったことから、キャパシタ特性の内部抵抗比率は７０％と大幅に低くなり（良化し）、また濡れ保持性も５秒と高くなった（良化した）ものの、空隙率が８０％と高くなり、平均孔径が０．２μｍと大きくなったことから、自己放電が増大しキャパシタ特性の電圧保持率は低下し（悪化し）、また機械的強度は引張強さ（ＭＤ）が１５Ｎ／ｍｍ２、突刺強度が１．３Ｎと、それぞれ約５０％、約３５％低下した。
（７）実施例３のセパレータに対し、界面活性剤の含有量を４．８質量％と変えず無機粉体の含有量を２２．０質量％と少なくしポリオレフィン系樹脂の含有量を７３．３質量％と多くした比較例３のセパレータでは、機械的強度は引張強さ（ＭＤ）が５０Ｎ／ｍｍ２、突刺強度が６Ｎと、それぞれ約６７％、約２００％向上したものの、親水性が６０秒と大幅に低くなり、空隙率も２０％と大幅に低くなったことから、キャパシタ特性の内部抵抗比率が８００％と大幅に高くなり（悪化し）、十分なキャパシタ性能を確保できないとともに、濡れ保持性も１５０秒と大幅に低くなった（悪化した）。但し、空隙率が２０％と低くなり、平均孔径が０．０１μｍと小さくなったことから、自己放電が抑えられキャパシタ特性の電圧保持率は８５％と高くなった（良化した）。
（８）実施例３のセパレータに対し、無機粉体のＢＥＴ比表面積を９０ｍ２／ｇと小さくした比較例４のセパレータでは、親水性が１０秒と低くなり、空隙率も４５％と低くなったことから、キャパシタ特性の内部抵抗比率が４００％と大幅に高くなり（悪化し）、十分なキャパシタ性能を確保できないとともに、濡れ保持性も１００秒と低くなった（悪化した）。
（９）実施例３のセパレータに対し、無機粉体のＢＥＴ比表面積を１５０ｍ２／ｇとやや小さくした実施例８のセパレータでは、親水性が２秒とやや低下し、空隙率も６５％とやや低下し、キャパシタ特性の内部抵抗比率は１２０％とやや高くなり（悪化し）、濡れ保持性も２０秒とやや低下した（悪化した）。
（１０）実施例３のセパレータに対し、無機粉体の疎水化度を２％とやや高くした実施例９のセパレータでは、空隙率は７０％と同等であったが、親水性が２秒とやや低下し（悪化し）、キャパシタ特性の内部抵抗比率は１１０％とやや高くなり（悪化し）、濡れ保持性も２０秒とやや低下した（悪化した）。また、空隙率が７０％と同等で、平均孔径も０．１μｍと同等であったことから、キャパシタ特性の電圧保持率は８１％と同等であった。
（１１）実施例３のセパレータに対し、無機粉体の疎水化度を５％と高くした実施例１０のセパレータでは、空隙率は７０％と同等であったが、親水性が５秒と低下し（悪化し）、キャパシタ特性の内部抵抗比率は１５０％と高くなり（悪化し）、濡れ保持性も５０秒と低下した（悪化した）。また、空隙率が７０％と同等で、平均孔径も０．１μｍと同等であったことから、キャパシタ特性の電圧保持率は８０％とほぼ同等であった。
（１２）実施例２のセパレータに対し、界面活性剤の添加方法を外添法に変え同量を添加した実施例５のセパレータでは、添加した界面活性剤を微多孔性フィルムの基材表面（細孔内外表面）に効率的に介在させられたことから、親水性が１秒と高くなった（良化した）。
（１３）実施例３のセパレータに対し、無機粉体の疎水化度を１０％と高くした比較例５のセパレータでは、親水性が１０秒と低くなった（悪化した）。但し、この親水性試験において、測定後の試験片を水面から引き上げると、水が浸透して半透明になっていた試験片が、しばらくして初期の白色に戻る現象が確認された。よって、キャパシタ特性については、蓄電デバイスの作製において、電解液をセパレータに十分に含浸させることができず、蓄電デバイスを完成させることができなかった。これは、比較例５のセパレータと電解液との濡れ性自体はある程度良好であり、比較例５のセパレータは電解液を一旦吸収することはできるものの、電解液を完全に保持することができず電解液が遊離してしまうと考えられる。また、濡れ保持性についても６００秒以上と著しい低下が見られ、電解液濡れ性（電解液保持性）の持続性が低いことがわかる。
（１４）実施例３のセパレータに対し、無機粉体の疎水化度を５０％と高くした比較例６のセパレータでは、親水性が３０秒と低くなった（悪化した）。但し、この親水性試験において、測定後の試験片を水面から引き上げると、水が浸透して半透明になっていた試験片が、しばらくして初期の白色に戻る現象が確認された。よって、キャパシタ特性については、蓄電デバイスの作製において、電解液をセパレータに十分に含浸させることができず、蓄電デバイスを完成させることができなかった。これは、比較例６のセパレータと電解液との濡れ性自体はある程度良好であり、比較例６のセパレータは電解液を一旦吸収することはできるものの、電解液を完全に保持することができず電解液が遊離してしまうと考えられる。また、濡れ保持性についても６００秒以上と著しい低下が見られ、電解液濡れ性（電解液保持性）の持続性が低いことがわかる。
（１５）実施例１〜４のセパレータに対し、界面活性剤の含有量をゼロとした比較例２のセパレータでは、親水性が１００秒以上と著しく低下し、キャパシタ特性については、蓄電デバイスの作製において、電解液をセパレータに十分に含浸させることができず、蓄電デバイスを完成させることができなかった。また、濡れ保持性についても６００秒以上と著しい低下が見られ、電解液濡れ性（電解液保持性）の持続性が低いことがわかる。
From the results in Table 1, the following was found.
(1) The separators of Examples 1 to 4 are microporous films composed of 28.4 to 33.0% by mass of a polyolefin-based resin, and have a BET specific surface area of 200 m 2 / g as an inorganic powder. In addition, an inorganic powder having a hydrophobization degree of 0% is selected, and an amount of 56.8 to 66.0% by mass is added, and then a surfactant is added to 1.0 to 14.8% by mass (internal addition method). ) By including, the thickness is 50 μm, the average pore diameter is 0.1 μm, the porosity is 63 to 72%, the mechanical strength is also the tensile strength (MD) is 27 to 30 N / mm 2 , the puncture strength 1.8 to 2N, hydrophilicity was good at 1 to 10 seconds, and wettability was also good at 10 to 40 seconds. Further, since the porosity was as high as 63 to 72% and the hydrophilicity was as good as 1 to 10 seconds, the internal resistance ratio of the capacitor characteristics was good as 100 to 130%, and the porosity was 63. Since the average pore diameter was 0.1 μm, the self-discharge was suppressed to some extent, and the voltage holding ratio of the capacitor characteristics was as good as 77 to 82%. In addition, since the internal resistance ratio of the capacitor characteristics was good at 100 to 130% and the wettability was also good at 10 to 40 seconds, the initial electrolyte wettability (electrolyte holdability) in the capacitor characteristics. It is presumed that the electrolyte solution is good and can maintain good electrolyte solution wettability (electrolyte retention) even after elapse of time associated with the use of the capacitor.
(2) Among them, in the separators of Examples 2 to 4 in which the surfactant content is 3.2 to 14.8% by mass of 3% by mass or more, the hydrophilicity is particularly good at 1 to 2 seconds, The wettability was also good at 10 seconds.
(3) Among them, in the separators of Examples 2-3 in which the surfactant content is 3.2 to 4.8% by mass of 3% by mass or more and 8% by mass or less, the porosity is good at 70 to 71%. In addition, the mechanical strength is good at a tensile strength (MD) of 30 N / mm 2 , the puncture strength is good at 2 N, the hydrophilicity is good at 1-2 seconds, the wet retention is good at 10 seconds, and the capacitor characteristics are good. The internal resistance ratio was also good at 100%, and the voltage holding ratio of the capacitor characteristics was also good at 81%.
(4) In the separator of Comparative Example 1 in which the surfactant content was increased to 20.0% by mass exceeding 15% by mass with respect to the separators of Examples 1 to 4, the hydrophilicity was good at 1 second and was wet. The retention was also good at 10 seconds, but the porosity was lowered to 60%, and the excess surfactant obstructed the pore path of the microporous film, so the internal resistance ratio of the capacitor characteristics was increased to 200%, In addition, the voltage holding ratio is as low as 58% due to an increase in self-discharge due to the excess surfactant, and sufficient capacitor performance cannot be ensured.
(5) With respect to the separator of Example 3, the surfactant content is not changed to 4.8% by mass, the inorganic powder content is reduced to 40.8% by mass, and the polyolefin resin content is 54.%. In the separator of Example 6 increased to 3 mass%, the mechanical strength was 45 N / mm 2 in tensile strength (MD) and 3 N, and the puncture strength was improved by about 50%, but the hydrophilicity was 5 seconds. Since it became low and the porosity became as low as 50%, the internal resistance ratio of the capacitor characteristics became high (deteriorated) as 150%, and the wettability was lowered (deteriorated) as 50 seconds. Further, since the porosity was as low as 50% and the average pore diameter was as small as 0.05 μm, self-discharge was suppressed, and the voltage holding ratio of the capacitor characteristics was as high as 85% (improved).
(6) For the separator of Example 3, the content of the inorganic powder was increased to 75.2% by mass without changing the surfactant content to 4.8% by mass, and the polyolefin resin content was 20. In the separator of Example 7, which was reduced to 0% by mass, the hydrophilicity was good at 1 second and the porosity was as high as 80%, so the internal resistance ratio of the capacitor characteristics was greatly reduced to 70% (good) Although the wettability increased to 5 seconds (improved), the porosity increased to 80% and the average pore diameter increased to 0.2 μm, which increased self-discharge and increased the capacitor characteristics. The voltage holding ratio was reduced (deteriorated), and the mechanical strength was reduced by about 50% and about 35%, respectively, with a tensile strength (MD) of 15 N / mm 2 and a puncture strength of 1.3 N.
(7) With respect to the separator of Example 3, the content of the surfactant is not changed to 4.8% by mass, the content of the inorganic powder is reduced to 22.0% by mass, and the content of the polyolefin resin is 73.3%. In the separator of Comparative Example 3 increased to 3% by mass, the mechanical strength was 50N / mm 2 in tensile strength (MD) and 6N, and the puncture strength was improved by about 67% and about 200%, respectively. Since it was significantly reduced to 60 seconds and the porosity was greatly reduced to 20%, the internal resistance ratio of the capacitor characteristics was greatly increased (deteriorated) to 800%, and sufficient capacitor performance could not be secured. The wettability was also significantly lowered (deteriorated) to 150 seconds. However, since the porosity was as low as 20% and the average pore diameter was as small as 0.01 μm, self-discharge was suppressed, and the voltage holding ratio of the capacitor characteristics was as high as 85% (improved).
(8) Compared to the separator of Example 3, the separator of Comparative Example 4 in which the BET specific surface area of the inorganic powder is as small as 90 m 2 / g, the hydrophilicity is as low as 10 seconds and the porosity is as low as 45%. As a result, the internal resistance ratio of the capacitor characteristics was significantly increased (deteriorated) to 400%, sufficient capacitor performance could not be ensured, and wettability was decreased (deteriorated) to 100 seconds.
(9) The separator of Example 8 in which the BET specific surface area of the inorganic powder was slightly reduced to 150 m 2 / g with respect to the separator of Example 3, the hydrophilicity was slightly reduced to 2 seconds, and the porosity was 65%. The internal resistance ratio of the capacitor characteristics slightly increased (deteriorated) to 120%, and the wettability decreased slightly (deteriorated) to 20 seconds.
(10) In the separator of Example 9 in which the hydrophobicity of the inorganic powder was slightly higher than 2% of the separator of Example 3, the porosity was equal to 70%, but the hydrophilicity was 2 seconds. The internal resistance ratio of the capacitor characteristics was slightly increased (deteriorated) to 110%, and the wettability was slightly decreased (deteriorated) to 20 seconds. In addition, since the porosity was equivalent to 70% and the average pore diameter was also equivalent to 0.1 μm, the voltage holding ratio of the capacitor characteristics was equivalent to 81%.
(11) In the separator of Example 10 in which the hydrophobicity of the inorganic powder was increased to 5% with respect to the separator of Example 3, the porosity was equal to 70%, but the hydrophilicity decreased to 5 seconds. However, the internal resistance ratio of the capacitor characteristics increased to 150% (deteriorated), and the wettability decreased to 50 seconds (deteriorated). In addition, since the porosity was equivalent to 70% and the average pore diameter was also equivalent to 0.1 μm, the voltage holding ratio of the capacitor characteristics was almost equivalent to 80%.
(12) In the separator of Example 5 in which the same amount was added to the separator of Example 2 except that the surfactant addition method was changed to the external addition method, the added surfactant was added to the substrate surface of the microporous film ( The hydrophilicity was increased to 1 second (improved) because it was efficiently interposed in the pore inner and outer surfaces).
(13) In the separator of Comparative Example 5 in which the hydrophobicity of the inorganic powder was increased to 10% with respect to the separator of Example 3, the hydrophilicity was lowered (deteriorated) to 10 seconds. However, in this hydrophilicity test, it was confirmed that when the test piece after measurement was pulled up from the water surface, the test piece, which had become translucent due to water penetration, returned to the initial white color after a while. Therefore, regarding the capacitor characteristics, in the production of the electricity storage device, the separator could not be sufficiently impregnated with the electrolyte, and the electricity storage device could not be completed. This is because the wettability itself between the separator of Comparative Example 5 and the electrolytic solution is good to some extent, and although the separator of Comparative Example 5 can absorb the electrolytic solution once, it cannot completely hold the electrolytic solution. It is considered that the electrolyte is liberated. Further, the wettability is remarkably lowered as 600 seconds or more, and it is understood that the sustainability of the electrolyte wettability (electrolyte holdability) is low.
(14) With respect to the separator of Example 3, the separator of Comparative Example 6 in which the degree of hydrophobicity of the inorganic powder was increased to 50%, the hydrophilicity was lowered (deteriorated) to 30 seconds. However, in this hydrophilicity test, it was confirmed that when the test piece after measurement was pulled up from the water surface, the test piece, which had become translucent due to water penetration, returned to the initial white color after a while. Therefore, regarding the capacitor characteristics, in the production of the electricity storage device, the separator could not be sufficiently impregnated with the electrolyte, and the electricity storage device could not be completed. This is because the wettability itself between the separator of Comparative Example 6 and the electrolytic solution is good to some extent, and although the separator of Comparative Example 6 can once absorb the electrolytic solution, it cannot completely hold the electrolytic solution. It is considered that the electrolyte is liberated. Further, the wettability is remarkably lowered as 600 seconds or more, and it is understood that the sustainability of the electrolyte wettability (electrolyte holdability) is low.
(15) With respect to the separators of Examples 1 to 4, the separator of Comparative Example 2 in which the surfactant content is zero, the hydrophilicity is remarkably reduced to 100 seconds or more. However, the separator could not be sufficiently impregnated with the electrolytic solution, and the electricity storage device could not be completed. Further, the wettability is remarkably lowered as 600 seconds or more, and it is understood that the sustainability of the electrolyte wettability (electrolyte holdability) is low.
Claims (3)
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し圧延及び／又は延伸による薄肉化成形と前記可塑剤の除去を行って得られる、厚さが１０〜１００μｍ、平均孔径が０．０１〜０．５μｍ、空隙率が５０〜９０％である微多孔性フィルムからなり、
前記無機粉体がＢＥＴ比表面積１００ｍ２／ｇ以上で疎水化度５％以下の親水性無機粉体で、前記原料組成物中には界面活性剤を含有し、
前記無機粉体の含有量が４０〜８０質量％、前記界面活性剤（固形分）の含有量が１〜１５質量％、前記ポリオレフィン系樹脂の含有量が２０〜６０質量％であることを特徴とする蓄電デバイス用セパレータ。 To an electricity storage device in which an electrolytic solution is substantially composed of only the ionic liquid or substantially only the ionic liquid and an electrolyte salt by using an ionic liquid having a surface tension (25 ° C., hanging drop method) of 48 mN / m or more. A separator to be used,
A raw material composition mainly composed of a polyolefin-based resin, an inorganic powder, and a plasticizer is melt-kneaded to form a film, which is obtained by performing thinning molding by rolling and / or stretching and removing the plasticizer, and has a thickness of 10 A microporous film having an average pore diameter of 0.01 to 0.5 μm and a porosity of 50 to 90%,
The inorganic powder is a hydrophilic inorganic powder having a BET specific surface area of 100 m 2 / g or more and a hydrophobicity of 5% or less, and the raw material composition contains a surfactant,
The content of the inorganic powder is 40 to 80% by mass, the content of the surfactant (solid content) is 1 to 15% by mass, and the content of the polyolefin resin is 20 to 60% by mass. A separator for an electricity storage device.
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し圧延及び／又は延伸による薄肉化成形と前記可塑剤の除去を行って得られる、厚さが１０〜１００μｍ、平均孔径が０．０１〜０．５μｍ、空隙率が５０〜９０％である微多孔性フィルムからなり、
前記無機粉体がＢＥＴ比表面積１００ｍ２／ｇ以上で疎水化度５％以下の親水性無機粉体で、前記原料組成物中には含有せず前記微多孔性フィルム中には界面活性剤を含有し、
前記無機粉体の含有量が４０〜８０質量％、前記界面活性剤（固形分）の含有量が０．５〜７質量％、前記ポリオレフィン系樹脂の含有量が２０〜６０質量％であることを特徴とする蓄電デバイス用セパレータ。 To an electricity storage device in which an electrolytic solution is substantially composed of only the ionic liquid or substantially only the ionic liquid and an electrolyte salt by using an ionic liquid having a surface tension (25 ° C., hanging drop method) of 48 mN / m or more. A separator to be used,
A raw material composition mainly composed of a polyolefin-based resin, an inorganic powder, and a plasticizer is melt-kneaded to form a film, which is obtained by performing thinning molding by rolling and / or stretching and removing the plasticizer, and has a thickness of 10 A microporous film having an average pore diameter of 0.01 to 0.5 μm and a porosity of 50 to 90%,
The inorganic powder is a hydrophilic inorganic powder having a BET specific surface area of 100 m 2 / g or more and a hydrophobization degree of 5% or less, and is not contained in the raw material composition and contains a surfactant in the microporous film. Contains,
The content of the inorganic powder is 40 to 80% by mass, the content of the surfactant (solid content) is 0.5 to 7% by mass, and the content of the polyolefin resin is 20 to 60% by mass. The separator for electrical storage devices characterized by this.
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| JP2017157398A (en) * | 2016-03-01 | 2017-09-07 | 株式会社日本触媒 | Anion conducting membrane |
| CN108305979A (en) * | 2018-01-09 | 2018-07-20 | 深圳中兴创新材料技术有限公司 | Composite diaphragm and its preparation method and application |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0594812A (en) * | 1991-10-03 | 1993-04-16 | Tonen Corp | Polyolefine microporous membrane and its manufacture, and separator using such membrane |
| JP2003031197A (en) * | 2001-07-11 | 2003-01-31 | Asahi Kasei Corp | Separator for cell |
| JP2005216992A (en) * | 2004-01-28 | 2005-08-11 | Nippon Sheet Glass Co Ltd | Separator for capacitor |
| JP2005268006A (en) * | 2004-03-18 | 2005-09-29 | Nippon Sheet Glass Co Ltd | Separator for storage battery, and its manufacturing method |
| 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 |
| JP2012079813A (en) * | 2010-09-30 | 2012-04-19 | Murata Mfg Co Ltd | Manufacturing method of electric storage device |
| WO2012165624A1 (en) * | 2011-06-03 | 2012-12-06 | 富士シリシア化学株式会社 | Separator, electrochemical element, and method for manufacturing separator |
-
2013
- 2013-03-15 JP JP2013053425A patent/JP2014179519A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0594812A (en) * | 1991-10-03 | 1993-04-16 | Tonen Corp | Polyolefine microporous membrane and its manufacture, and separator using such membrane |
| JP2003031197A (en) * | 2001-07-11 | 2003-01-31 | Asahi Kasei Corp | Separator for cell |
| JP2005216992A (en) * | 2004-01-28 | 2005-08-11 | Nippon Sheet Glass Co Ltd | Separator for capacitor |
| JP2005268006A (en) * | 2004-03-18 | 2005-09-29 | Nippon Sheet Glass Co Ltd | Separator for storage battery, and its manufacturing method |
| 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 |
| JP2012079813A (en) * | 2010-09-30 | 2012-04-19 | Murata Mfg Co Ltd | Manufacturing method of electric storage device |
| WO2012165624A1 (en) * | 2011-06-03 | 2012-12-06 | 富士シリシア化学株式会社 | Separator, electrochemical element, and method for manufacturing separator |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2017157398A (en) * | 2016-03-01 | 2017-09-07 | 株式会社日本触媒 | Anion conducting membrane |
| CN108305979A (en) * | 2018-01-09 | 2018-07-20 | 深圳中兴创新材料技术有限公司 | Composite diaphragm and its preparation method and application |
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