JP6221447B2 - Porous film and separator for electricity storage device - Google Patents
Porous film and separator for electricity storage device Download PDFInfo
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- JP6221447B2 JP6221447B2 JP2013149405A JP2013149405A JP6221447B2 JP 6221447 B2 JP6221447 B2 JP 6221447B2 JP 2013149405 A JP2013149405 A JP 2013149405A JP 2013149405 A JP2013149405 A JP 2013149405A JP 6221447 B2 JP6221447 B2 JP 6221447B2
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- resin
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- film
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- 238000003860 storage Methods 0.000 title claims description 12
- 230000005611 electricity Effects 0.000 title description 8
- 229920005989 resin Polymers 0.000 claims description 114
- 239000011347 resin Substances 0.000 claims description 114
- 239000002245 particle Substances 0.000 claims description 107
- 238000002844 melting Methods 0.000 claims description 47
- 230000008018 melting Effects 0.000 claims description 47
- 239000013078 crystal Substances 0.000 claims description 37
- 239000011248 coating agent Substances 0.000 claims description 35
- 238000000576 coating method Methods 0.000 claims description 33
- 239000000463 material Substances 0.000 claims description 21
- 239000011148 porous material Substances 0.000 claims description 19
- 230000004927 fusion Effects 0.000 claims description 14
- 239000007787 solid Substances 0.000 claims description 10
- 229920002678 cellulose Polymers 0.000 claims description 8
- 239000001913 cellulose Substances 0.000 claims description 8
- 229920000098 polyolefin Polymers 0.000 claims description 8
- 238000004519 manufacturing process Methods 0.000 claims description 7
- 239000000126 substance Substances 0.000 claims description 7
- 150000003839 salts Chemical class 0.000 claims description 6
- 238000002076 thermal analysis method Methods 0.000 claims description 6
- 239000010408 film Substances 0.000 description 242
- 239000010410 layer Substances 0.000 description 117
- 238000000034 method Methods 0.000 description 46
- -1 polyethylene Polymers 0.000 description 42
- 239000004743 Polypropylene Substances 0.000 description 34
- 229920001155 polypropylene Polymers 0.000 description 34
- 239000000758 substrate Substances 0.000 description 18
- 230000035699 permeability Effects 0.000 description 17
- 230000008859 change Effects 0.000 description 14
- 239000000203 mixture Substances 0.000 description 14
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 13
- 238000001035 drying Methods 0.000 description 10
- 238000004544 sputter deposition Methods 0.000 description 10
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 10
- 230000005484 gravity Effects 0.000 description 9
- 239000003484 crystal nucleating agent Substances 0.000 description 7
- 230000008569 process Effects 0.000 description 7
- 239000002994 raw material Substances 0.000 description 7
- 239000011230 binding agent Substances 0.000 description 6
- 229910000019 calcium carbonate Inorganic materials 0.000 description 6
- 239000006185 dispersion Substances 0.000 description 6
- PCHJSUWPFVWCPO-UHFFFAOYSA-N gold Chemical compound [Au] PCHJSUWPFVWCPO-UHFFFAOYSA-N 0.000 description 6
- 239000010931 gold Substances 0.000 description 6
- 229910052737 gold Inorganic materials 0.000 description 6
- 238000005259 measurement Methods 0.000 description 6
- 229920005672 polyolefin resin Polymers 0.000 description 6
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 5
- 239000005977 Ethylene Substances 0.000 description 5
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 5
- 239000004698 Polyethylene Substances 0.000 description 5
- 239000003960 organic solvent Substances 0.000 description 5
- 229920000573 polyethylene Polymers 0.000 description 5
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 4
- 150000001875 compounds Chemical class 0.000 description 4
- 229920001577 copolymer Polymers 0.000 description 4
- 239000002612 dispersion medium Substances 0.000 description 4
- 230000000694 effects Effects 0.000 description 4
- 238000001125 extrusion Methods 0.000 description 4
- 230000000704 physical effect Effects 0.000 description 4
- 229920000642 polymer Polymers 0.000 description 4
- 239000004711 α-olefin Substances 0.000 description 4
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-Butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 3
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 3
- 229920000089 Cyclic olefin copolymer Polymers 0.000 description 3
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 3
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 3
- 239000003963 antioxidant agent Substances 0.000 description 3
- 239000012298 atmosphere Substances 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 3
- 239000001768 carboxy methyl cellulose Substances 0.000 description 3
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 3
- 150000001732 carboxylic acid derivatives Chemical group 0.000 description 3
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 3
- 230000000052 comparative effect Effects 0.000 description 3
- 238000003851 corona treatment Methods 0.000 description 3
- 238000005520 cutting process Methods 0.000 description 3
- 238000011156 evaluation Methods 0.000 description 3
- 238000009472 formulation Methods 0.000 description 3
- 239000007788 liquid Substances 0.000 description 3
- 229910001416 lithium ion Inorganic materials 0.000 description 3
- 239000000155 melt Substances 0.000 description 3
- 239000012299 nitrogen atmosphere Substances 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- NIXOWILDQLNWCW-UHFFFAOYSA-N 2-Propenoic acid Natural products OC(=O)C=C NIXOWILDQLNWCW-UHFFFAOYSA-N 0.000 description 2
- MBSRTKPGZKQXQR-UHFFFAOYSA-N 2-n,6-n-dicyclohexylnaphthalene-2,6-dicarboxamide Chemical compound C=1C=C2C=C(C(=O)NC3CCCCC3)C=CC2=CC=1C(=O)NC1CCCCC1 MBSRTKPGZKQXQR-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 description 2
- VZCYOOQTPOCHFL-OWOJBTEDSA-N Fumaric acid Chemical compound OC(=O)\C=C\C(O)=O VZCYOOQTPOCHFL-OWOJBTEDSA-N 0.000 description 2
- 239000004354 Hydroxyethyl cellulose Substances 0.000 description 2
- 229920000663 Hydroxyethyl cellulose Polymers 0.000 description 2
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 2
- 150000001336 alkenes Chemical class 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 2
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 2
- 230000003078 antioxidant effect Effects 0.000 description 2
- 239000003990 capacitor Substances 0.000 description 2
- 238000011109 contamination Methods 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 238000007334 copolymerization reaction Methods 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000009998 heat setting Methods 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 235000019447 hydroxyethyl cellulose Nutrition 0.000 description 2
- 238000010191 image analysis Methods 0.000 description 2
- 229910052738 indium Inorganic materials 0.000 description 2
- APFVFJFRJDLVQX-UHFFFAOYSA-N indium atom Chemical compound [In] APFVFJFRJDLVQX-UHFFFAOYSA-N 0.000 description 2
- 239000010954 inorganic particle Substances 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 239000011255 nonaqueous electrolyte Substances 0.000 description 2
- 239000011146 organic particle Substances 0.000 description 2
- YWAKXRMUMFPDSH-UHFFFAOYSA-N pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 description 2
- 229920005633 polypropylene homopolymer resin Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 230000002040 relaxant effect Effects 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 238000000992 sputter etching Methods 0.000 description 2
- 238000004381 surface treatment Methods 0.000 description 2
- 229920005992 thermoplastic resin Polymers 0.000 description 2
- VZCYOOQTPOCHFL-UHFFFAOYSA-N trans-butenedioic acid Natural products OC(=O)C=CC(O)=O VZCYOOQTPOCHFL-UHFFFAOYSA-N 0.000 description 2
- 230000007704 transition Effects 0.000 description 2
- KWKAKUADMBZCLK-UHFFFAOYSA-N 1-octene Chemical compound CCCCCCC=C KWKAKUADMBZCLK-UHFFFAOYSA-N 0.000 description 1
- SMZOUWXMTYCWNB-UHFFFAOYSA-N 2-(2-methoxy-5-methylphenyl)ethanamine Chemical compound COC1=CC=C(C)C=C1CCN SMZOUWXMTYCWNB-UHFFFAOYSA-N 0.000 description 1
- JAHNSTQSQJOJLO-UHFFFAOYSA-N 2-(3-fluorophenyl)-1h-imidazole Chemical compound FC1=CC=CC(C=2NC=CN=2)=C1 JAHNSTQSQJOJLO-UHFFFAOYSA-N 0.000 description 1
- OFNISBHGPNMTMS-UHFFFAOYSA-N 3-methylideneoxolane-2,5-dione Chemical compound C=C1CC(=O)OC1=O OFNISBHGPNMTMS-UHFFFAOYSA-N 0.000 description 1
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 1
- 239000004925 Acrylic resin Substances 0.000 description 1
- 229920000178 Acrylic resin Polymers 0.000 description 1
- 229910021532 Calcite Inorganic materials 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 229920002153 Hydroxypropyl cellulose Polymers 0.000 description 1
- DGAQECJNVWCQMB-PUAWFVPOSA-M Ilexoside XXIX Chemical compound C[C@@H]1CC[C@@]2(CC[C@@]3(C(=CC[C@H]4[C@]3(CC[C@@H]5[C@@]4(CC[C@@H](C5(C)C)OS(=O)(=O)[O-])C)C)[C@@H]2[C@]1(C)O)C)C(=O)O[C@H]6[C@@H]([C@H]([C@@H]([C@H](O6)CO)O)O)O.[Na+] DGAQECJNVWCQMB-PUAWFVPOSA-M 0.000 description 1
- WHXSMMKQMYFTQS-UHFFFAOYSA-N Lithium Chemical compound [Li] WHXSMMKQMYFTQS-UHFFFAOYSA-N 0.000 description 1
- 208000030984 MIRAGE syndrome Diseases 0.000 description 1
- CERQOIWHTDAKMF-UHFFFAOYSA-N Methacrylic acid Chemical compound CC(=C)C(O)=O CERQOIWHTDAKMF-UHFFFAOYSA-N 0.000 description 1
- 239000002033 PVDF binder Substances 0.000 description 1
- JKIJEFPNVSHHEI-UHFFFAOYSA-N Phenol, 2,4-bis(1,1-dimethylethyl)-, phosphite (3:1) Chemical compound CC(C)(C)C1=CC(C(C)(C)C)=CC=C1OP(OC=1C(=CC(=CC=1)C(C)(C)C)C(C)(C)C)OC1=CC=C(C(C)(C)C)C=C1C(C)(C)C JKIJEFPNVSHHEI-UHFFFAOYSA-N 0.000 description 1
- 239000004696 Poly ether ether ketone Substances 0.000 description 1
- 239000004962 Polyamide-imide Substances 0.000 description 1
- 239000004697 Polyetherimide Substances 0.000 description 1
- 239000004642 Polyimide Substances 0.000 description 1
- 239000004734 Polyphenylene sulfide Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- OFOBLEOULBTSOW-UHFFFAOYSA-N Propanedioic acid Natural products OC(=O)CC(O)=O OFOBLEOULBTSOW-UHFFFAOYSA-N 0.000 description 1
- BGYHLZZASRKEJE-UHFFFAOYSA-N [3-[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxy]-2,2-bis[3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoyloxymethyl]propyl] 3-(3,5-ditert-butyl-4-hydroxyphenyl)propanoate Chemical compound CC(C)(C)C1=C(O)C(C(C)(C)C)=CC(CCC(=O)OCC(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)(COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)COC(=O)CCC=2C=C(C(O)=C(C=2)C(C)(C)C)C(C)(C)C)=C1 BGYHLZZASRKEJE-UHFFFAOYSA-N 0.000 description 1
- 125000004018 acid anhydride group Chemical group 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 239000000853 adhesive Substances 0.000 description 1
- 230000001070 adhesive effect Effects 0.000 description 1
- 150000001408 amides Chemical class 0.000 description 1
- 150000003863 ammonium salts Chemical class 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 238000007611 bar coating method Methods 0.000 description 1
- 239000011324 bead Substances 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- 238000012661 block copolymerization Methods 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- IAQRGUVFOMOMEM-UHFFFAOYSA-N butene Natural products CC=CC IAQRGUVFOMOMEM-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 description 1
- 239000000919 ceramic Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000008199 coating composition Substances 0.000 description 1
- 238000009838 combustion analysis Methods 0.000 description 1
- LDHQCZJRKDOVOX-NSCUHMNNSA-N crotonic acid Chemical compound C\C=C\C(O)=O LDHQCZJRKDOVOX-NSCUHMNNSA-N 0.000 description 1
- 150000001991 dicarboxylic acids Chemical class 0.000 description 1
- 238000007607 die coating method Methods 0.000 description 1
- NJLLQSBAHIKGKF-UHFFFAOYSA-N dipotassium dioxido(oxo)titanium Chemical compound [K+].[K+].[O-][Ti]([O-])=O NJLLQSBAHIKGKF-UHFFFAOYSA-N 0.000 description 1
- 208000028659 discharge Diseases 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 239000000839 emulsion Substances 0.000 description 1
- 150000002148 esters Chemical class 0.000 description 1
- 239000002657 fibrous material Substances 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 238000011049 filling Methods 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 239000001530 fumaric acid Substances 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000007756 gravure coating Methods 0.000 description 1
- 239000012760 heat stabilizer Substances 0.000 description 1
- 239000001863 hydroxypropyl cellulose Substances 0.000 description 1
- 235000010977 hydroxypropyl cellulose Nutrition 0.000 description 1
- 150000003949 imides Chemical class 0.000 description 1
- 230000006872 improvement Effects 0.000 description 1
- 239000011229 interlayer Substances 0.000 description 1
- 230000010220 ion permeability Effects 0.000 description 1
- 150000002500 ions Chemical class 0.000 description 1
- 229920000092 linear low density polyethylene Polymers 0.000 description 1
- 239000004707 linear low-density polyethylene Substances 0.000 description 1
- 229920005679 linear ultra low density polyethylene Polymers 0.000 description 1
- 229910052744 lithium Inorganic materials 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- VZCYOOQTPOCHFL-UPHRSURJSA-N maleic acid Chemical compound OC(=O)\C=C/C(O)=O VZCYOOQTPOCHFL-UPHRSURJSA-N 0.000 description 1
- 239000011976 maleic acid Substances 0.000 description 1
- FPYJFEHAWHCUMM-UHFFFAOYSA-N maleic anhydride Chemical compound O=C1OC(=O)C=C1 FPYJFEHAWHCUMM-UHFFFAOYSA-N 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229920000609 methyl cellulose Polymers 0.000 description 1
- 239000001923 methylcellulose Substances 0.000 description 1
- 235000010981 methylcellulose Nutrition 0.000 description 1
- LVHBHZANLOWSRM-UHFFFAOYSA-N methylenebutanedioic acid Natural products OC(=O)CC(=C)C(O)=O LVHBHZANLOWSRM-UHFFFAOYSA-N 0.000 description 1
- 239000000178 monomer Substances 0.000 description 1
- 239000002667 nucleating agent Substances 0.000 description 1
- JRZJOMJEPLMPRA-UHFFFAOYSA-N olefin Natural products CCCCCCCC=C JRZJOMJEPLMPRA-UHFFFAOYSA-N 0.000 description 1
- 239000012044 organic layer Substances 0.000 description 1
- 238000010525 oxidative degradation reaction Methods 0.000 description 1
- 125000000466 oxiranyl group Chemical group 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 238000009832 plasma treatment Methods 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920002312 polyamide-imide Polymers 0.000 description 1
- 229920001748 polybutylene Polymers 0.000 description 1
- 229920002530 polyetherether ketone Polymers 0.000 description 1
- 229920001601 polyetherimide Polymers 0.000 description 1
- 229920001721 polyimide Polymers 0.000 description 1
- 229920000069 polyphenylene sulfide Polymers 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- 229920002981 polyvinylidene fluoride Polymers 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- TVLSRXXIMLFWEO-UHFFFAOYSA-N prochloraz Chemical compound C1=CN=CN1C(=O)N(CCC)CCOC1=C(Cl)C=C(Cl)C=C1Cl TVLSRXXIMLFWEO-UHFFFAOYSA-N 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 238000005096 rolling process Methods 0.000 description 1
- 238000005070 sampling Methods 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 235000015424 sodium Nutrition 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 230000000087 stabilizing effect Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 230000003746 surface roughness Effects 0.000 description 1
- 238000005979 thermal decomposition reaction Methods 0.000 description 1
- 229920002803 thermoplastic polyurethane Polymers 0.000 description 1
- 230000008719 thickening Effects 0.000 description 1
- 239000002562 thickening agent Substances 0.000 description 1
- 239000010409 thin film Substances 0.000 description 1
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 description 1
- LDHQCZJRKDOVOX-UHFFFAOYSA-N trans-crotonic acid Natural products CC=CC(O)=O LDHQCZJRKDOVOX-UHFFFAOYSA-N 0.000 description 1
- 229920001862 ultra low molecular weight polyethylene Polymers 0.000 description 1
- 239000011800 void material Substances 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
- 229910052882 wollastonite Inorganic materials 0.000 description 1
- 239000010456 wollastonite 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
Landscapes
- Laminated Bodies (AREA)
- Electric Double-Layer Capacitors Or The Like (AREA)
- Cell Separators (AREA)
Description
本発明は、安全性に優れる蓄電デバイス用セパレータに関する。詳しくは、多孔フィルムに多孔層を設けることにより、優れた安全性を有し、かつ優れたフィルム物性を有する蓄電デバイス用セパレータ用として好適な多孔質フィルムに関する。 The present invention relates to a separator for an electricity storage device that is excellent in safety. Specifically, the present invention relates to a porous film suitable for use as an electricity storage device separator having excellent safety and excellent film physical properties by providing a porous layer on the porous film.
ポリオレフィンからなる多孔フィルムは、電気絶縁性やイオン透過性に加えて、力学特性にも優れることから、特にリチウムイオン二次電池のセパレータ用途に広く用いられており、なおかつ、電池の高出力密度、高エネルギー密度化に伴い、フィルムの大孔径化、薄膜化、高空孔率化などが検討されている（例えば、特許文献１、２参照）。しかし、このような方法で作られた多孔フィルムだけでは、耐熱性や熱寸法安定性が不足するといった点や、電池内部に混入した異物の貫通を阻止できないといった安全性に劣るという問題があった。安全性を確保するために、他素材間（耐熱粒子間、耐熱粒子−基材間など）を結着する樹脂（結着剤）と耐熱粒子からなる多孔層を基材である多孔フィルムに薄膜塗工する提案がなされているが（例えば、特許文献３、４）、結着剤の耐熱粒子・基材との密着性が不十分であることから、多孔層表面からの粒子の脱落や、基材から多孔層が剥離するといった問題があった。また、耐熱多孔層に有機粒子を加える提案がなされているが（例えば、特許文献５）、その融点が高いため、多孔層を形成する加工中に粒子が形状を維持するため、実質的に結着剤としては機能しないため結着性が改善されないといった問題があった。 A porous film made of polyolefin has excellent mechanical properties in addition to electrical insulation and ion permeability, and is therefore widely used especially for separator applications of lithium ion secondary batteries. With increasing energy density, studies have been made on increasing the diameter of a film, reducing the film thickness, increasing the porosity, and the like (see, for example, Patent Documents 1 and 2). However, only the porous film made by such a method has problems such as insufficient heat resistance and thermal dimensional stability, and inferior safety such that penetration of foreign matters mixed in the battery cannot be prevented. . In order to ensure safety, a porous layer consisting of a resin (binding agent) that binds between other materials (between heat-resistant particles, between heat-resistant particles and a substrate, etc.) and heat-resistant particles is formed into a thin film on the porous film as the substrate. Although the proposal to apply has been made (for example, Patent Documents 3 and 4), since the adhesiveness of the binder with the heat-resistant particles and the substrate is insufficient, dropping of particles from the surface of the porous layer, There was a problem that the porous layer was peeled off from the substrate. In addition, although proposals have been made to add organic particles to the heat-resistant porous layer (for example, Patent Document 5), since the melting point is high, the particles maintain their shape during the processing to form the porous layer, so that the particles are substantially bonded. There is a problem that the binding property is not improved because it does not function as an adhesive.
本発明の課題は、上記した問題点を解決することにある。すなわち、本発明の目的は、樹脂からなる多孔フィルムに多孔層を設けることにより、優れた安全性および優れたフィルム物性を有し、特に１７０℃での熱収縮を抑制し、耐熱性に優れ、蓄電デバイス用セパレータとして好適な多孔質フィルムを提供することにある。 An object of the present invention is to solve the above-described problems. That is, the object of the present invention is to provide a porous layer made of a resin with a porous layer, thereby having excellent safety and excellent film physical properties, particularly suppressing heat shrinkage at 170 ° C. and excellent heat resistance, It is providing the porous film suitable as a separator for electrical storage devices.
上記課題を解決するための本発明は、アスペクト比（耐熱粒子の長径／耐熱粒子の短径）が１以上１．５未満である耐熱粒子、樹脂（Ａ）並びにセルロースおよび／またはセルロース塩を含む多孔層と、樹脂（Ｂ）を含む多孔フィルムとで構成される多孔質フィルムであって、樹脂（Ａ）が変性ポリオレフィンであり、多孔層に含まれる耐熱粒子の濃度は６０質量％以上９５質量％未満であり、多孔層の熱分析において７０〜１２０℃に検出される吸熱ピークの融解熱量（ΔＨ）が０．０１Ｊ／ｇ以上１０Ｊ／ｇ未満である多孔質フィルムであることを特徴とする。 The present invention for solving the above problems includes heat-resistant particles, resin (A), and cellulose and / or cellulose salt having an aspect ratio (major axis of heat-resistant particles / minor axis of heat-resistant particles) of 1 or more and less than 1.5. A porous film composed of a porous layer and a porous film containing a resin (B), wherein the resin (A) is a modified polyolefin, and the concentration of heat-resistant particles contained in the porous layer is 60% by mass or more and 95% by mass. %, And the heat of fusion (ΔH) of the endothermic peak detected at 70 to 120 ° C. in the thermal analysis of the porous layer is a porous film having a value of 0.01 J / g or more and less than 10 J / g. .
本発明の多孔質フィルムは、多孔フィルムに多孔層を設けることにより、優れた安全性を有し、かつ優れたフィルム物性を有する、蓄電デバイス用セパレータとして用いた際に優れた特性を示す多孔質フィルムとして提供することができる。 The porous film of the present invention has excellent safety when used as a separator for an electricity storage device, having excellent safety by providing a porous layer on the porous film, and having excellent film properties. It can be provided as a film.
本発明において多孔質フィルムとは多孔フィルムと多孔層とで構成された積層フィルムをいう。 In the present invention, the porous film refers to a laminated film composed of a porous film and a porous layer.
本発明において多孔フィルムとは、樹脂（Ｂ）を含む、透気性を有する微多孔膜であり、多孔質フィルムの基材として用いる。この樹脂（Ｂ）は、多孔フィルム中の主成分であることが好ましい。ここで主成分とは多孔フィルムを構成する原料の８０質量％以上を占めることをいう。 In the present invention, the porous film is a gas-permeable microporous film containing the resin (B), and is used as a substrate for the porous film. This resin (B) is preferably the main component in the porous film. Here, the main component means that 80% by mass or more of the raw material constituting the porous film is occupied.
本発明において多孔層は、耐熱粒子と樹脂（Ａ）とを含んでいる。 In the present invention, the porous layer contains heat-resistant particles and a resin (A).
上記の多孔フィルムは樹脂（Ｂ）を含み、好ましくは主成分として構成され、フィルムの両表面を貫通し、透気性を有する微細な貫通孔を多数有している。 Said porous film contains resin (B), Preferably it is comprised as a main component and has many fine through-holes which penetrate the both surfaces of a film and have air permeability.
多孔フィルムに含まれる樹脂（Ｂ）としては、オレフィン系樹脂やフッ素系樹脂、イミド系樹脂、ウレタン系樹脂、アクリル系樹脂などを用いることができるが、オレフィン系樹脂が加工のしやすさやコストといった製造面が優れる点と高いイオン伝導度を両立する観点から好ましい。 As the resin (B) contained in the porous film, an olefin resin, a fluorine resin, an imide resin, a urethane resin, an acrylic resin, or the like can be used, but the olefin resin is easy to process and costs. It is preferable from the viewpoint of achieving both excellent manufacturing aspects and high ionic conductivity.
オレフィン系樹脂としては、ポリエチレンやポリプロピレン、ポリブテン−１、ポリ４−メチルペンテン−１などの単一ポリオレフィン樹脂や、これら樹脂の混合物、さらには、単量体同士をランダム共重合やブロック共重合した樹脂を用いることができる。 As the olefin resin, a single polyolefin resin such as polyethylene, polypropylene, polybutene-1, and poly-4-methylpentene-1, a mixture of these resins, and monomers are randomly copolymerized or block copolymerized. Resin can be used.
多孔フィルムは、耐熱性の観点で融点が１１０℃以上であることが好ましい。融点が１１０℃未満であると多孔層を多孔フィルム上に積層する際に多孔フィルムが寸法変化してしまう場合がある。多孔フィルムの融点は、単一の融点を示す場合はもちろんその融点をいうが、例えば多孔フィルムがポリオレフィンの混合物から構成されるなど、複数の融点を有している場合は、そのうち最も高温側に現れる融点を多孔フィルムの融点とする。多孔フィルムの融点は、より好ましくは耐熱性の観点から１３０℃以上である。また、上記したように、多孔フィルムが複数の融点を示す場合は、それら全てが上記範囲内にあることが好ましい。 The porous film preferably has a melting point of 110 ° C. or higher from the viewpoint of heat resistance. When the melting point is less than 110 ° C., the porous film may change dimensions when the porous layer is laminated on the porous film. The melting point of the porous film is, of course, the melting point when showing a single melting point.For example, when the porous film has a plurality of melting points such as a mixture of polyolefins, The melting point that appears is the melting point of the porous film. The melting point of the porous film is more preferably 130 ° C. or higher from the viewpoint of heat resistance. Moreover, as above-mentioned, when a porous film shows several melting | fusing point, it is preferable that all of them exist in the said range.
多孔フィルムに用いる樹脂としては前述した耐熱性の観点と、フィルムの厚み方向に貫通孔を形成するための加工性を両立する観点から、後述する種類のポリプロピレン樹脂を用いることが好ましい。 As the resin used for the porous film, it is preferable to use the type of polypropylene resin described later from the viewpoint of achieving both the heat resistance viewpoint described above and the workability for forming a through hole in the thickness direction of the film.
本発明において基材に用いる多孔フィルムは、その中に含まれる樹脂（Ｂ）がβ晶形成能を有することが好ましい。樹脂（Ｂ）がβ晶形成能を有すると、後述するβ晶法によるフィルムの多孔化により多孔フィルムを製造することができる。β晶法によって得られる多孔フィルムは、生産性に優れ、多孔層を積層した際にアンカー効果による高い接着性を発現するのに適した表面の開孔径（表面孔径）を持つことから、多孔質フィルムの基材として好適に用いることができる。 In the porous film used for the substrate in the present invention, it is preferable that the resin (B) contained therein has β-crystal forming ability. When the resin (B) has β crystal forming ability, a porous film can be produced by making the film porous by the β crystal method described later. The porous film obtained by the β crystal method has excellent productivity and has a surface pore size (surface pore size) suitable for developing high adhesion due to the anchor effect when a porous layer is laminated. It can be suitably used as a film substrate.
本発明においてβ晶法とは、β晶形成能を有する樹脂をシート化した後、延伸によってフィルムに貫通孔を形成する手法をいう。 In the present invention, the β crystal method refers to a method of forming a through hole in a film by stretching after forming a resin having β crystal forming ability into a sheet.
本発明において多孔フィルムに用いる樹脂（Ｂ）にβ晶形成能を付与する手法としては、樹脂の結晶種のうちβ晶を選択的に形成できる核剤（β晶核剤）を含有せしめることで達成できる。ポリプロピレン樹脂のβ晶核剤としては種々の顔料系化合物やアミド系化合物などを挙げることができるが、特に特開平５−３１０６６５号公報に開示されているアミド系化合物を好ましく用いることができる。β晶核剤の含有量としては、ポリプロピレン樹脂全体を１００質量部とした場合、０．０５〜０．５質量部であることが好ましく、０．１〜０．３質量部であればより好ましい。 In the present invention, the resin (B) used for the porous film is imparted with a β crystal forming ability by including a nucleating agent (β crystal nucleating agent) capable of selectively forming β crystals out of the resin crystal seeds. Can be achieved. Examples of the β crystal nucleating agent for the polypropylene resin include various pigment compounds and amide compounds. Particularly, amide compounds disclosed in JP-A-5-310665 can be preferably used. As content of (beta) crystal nucleating agent, when the whole polypropylene resin is 100 mass parts, it is preferable that it is 0.05-0.5 mass part, and more preferable if it is 0.1-0.3 mass part. .
本発明において、β晶形成能とは以下の条件で測定される、一定条件下におけるポリプロピレン樹脂中のβ晶の存在比率を示しており、β晶をどれだけ形成する能力があるのかを示す値である。β晶形成能の測定は、ポリプロピレン樹脂あるいはポリプロピレンフィルム５ｍｇを、示差走査熱量計を用いて窒素雰囲気下で室温から２４０℃まで１０℃／分で昇温（ファーストラン）し、１０分間保持した後、３０℃まで１０℃／分で冷却する。５分保持後、再度１０℃／分で昇温（セカンドラン）した際に観察される融解ピークについて、１４５〜１５７℃の温度領域にピークが存在する融解をβ晶の融解ピーク、１５８℃以上にピークが観察される融解をα晶の融解ピークとして、それぞれ融解熱量を求め、α晶の融解熱量をΔＨα、β晶の融解熱量をΔＨβとしたとき、以下の式で計算される値をβ晶形成能とする。 In the present invention, the β crystal-forming ability indicates the abundance ratio of β-crystals in a polypropylene resin measured under the following conditions, and is a value indicating how much β-crystals are formed. It is. The β crystal-forming ability was measured after 5 mg of polypropylene resin or polypropylene film was heated from room temperature to 240 ° C. at a rate of 10 ° C./min (first run) using a differential scanning calorimeter and held for 10 minutes. Cool to 30 ° C. at 10 ° C./min. About the melting peak observed when the temperature is raised (second run) again at 10 ° C./min after holding for 5 minutes, the melting having a peak in the temperature range of 145 to 157 ° C. is the melting peak of β crystal, 158 ° C. or more The melting at which the peak is observed is the melting peak of the α crystal, and the heat of fusion is determined. The heat of fusion of the α crystal is ΔHα and the heat of fusion of the β crystal is ΔHβ. Crystal formation ability.
β晶形成能（％）＝〔ΔＨβ／（ΔＨα＋ΔＨβ）〕×１００
本発明において基材に用いる多孔フィルムを構成する（含まれる）ポリプロピレン樹脂（樹脂（Ｂ））のβ晶形成能は高い空孔率と好適な透気抵抗を発現せしめる観点から、４０〜９０％であることが好ましい。β晶形成能が４０％未満ではフィルム製造時にβ晶量が少ないためにα晶への転移を利用してフィルム中に形成される空隙数が少なくなり、その結果透過性の低いフィルムしか得られない場合がある。また、β晶形成能が９０％を超える場合は、粗大孔が形成され、蓄電デバイス用セパレータとしての機能を有さなくなる場合がある。β晶形成能を４０〜９０％の範囲内にするためには、アイソタクチックインデックスの高いポリプロピレン樹脂を使用し、かつ、上述のβ晶核剤を添加することが好ましい。β晶形成能としては４５〜８０％であればより好ましい。
β crystal forming ability (%) = [ΔHβ / (ΔHα + ΔHβ)] × 100
In the present invention, the β-crystal forming ability of the polypropylene resin (resin (B)) that constitutes (includes) the porous film used as the base material in the present invention is 40 to 90% from the viewpoint of developing a high porosity and suitable air resistance. It is preferable that If the β-crystal forming ability is less than 40%, the amount of β-crystal is small at the time of film production, so the number of voids formed in the film is reduced by utilizing the transition to α-crystal, and as a result, only a film with low permeability is obtained. There may not be. In addition, when the β-crystal forming ability exceeds 90%, coarse pores are formed, and the function as a power storage device separator may not be provided. In order to make the β crystal forming ability in the range of 40 to 90%, it is preferable to use a polypropylene resin having a high isotactic index and to add the above-mentioned β crystal nucleating agent. The β crystal forming ability is more preferably 45 to 80%.
本発明において多孔フィルムを構成するポリプロピレン樹脂はメルトフローレート（以下、ＭＦＲと表記する、測定条件は２３０℃、２．１６ｋｇ）が２〜３０ｇ／１０分の範囲のアイソタクチックポリプロピレン樹脂であることが好ましい。ＭＦＲが上記した好ましい範囲を外れると延伸フィルムを得ることが困難となる場合がある。より好ましくは、ＭＦＲが３〜２０ｇ／１０分である。 In the present invention, the polypropylene resin constituting the porous film is an isotactic polypropylene resin having a melt flow rate (hereinafter referred to as MFR, measurement conditions are 230 ° C., 2.16 kg) in the range of 2 to 30 g / 10 min. Is preferred. If the MFR is out of the above preferred range, it may be difficult to obtain a stretched film. More preferably, the MFR is 3 to 20 g / 10 minutes.
また、アイソタクチックポリプロピレン樹脂のアイソタクチックインデックスは９０〜９９．９％であれば好ましい。アイソタクチックインデックスが９０％未満であると、樹脂の結晶性が低く、高い透気性を達成するのが困難な場合がある。アイソタクチックポリプロピレン樹脂は市販されている樹脂を用いることができる。 The isotactic index of the isotactic polypropylene resin is preferably 90 to 99.9%. If the isotactic index is less than 90%, the crystallinity of the resin is low, and it may be difficult to achieve high air permeability. A commercially available resin can be used as the isotactic polypropylene resin.
多孔フィルムにはホモポリプロピレン樹脂を用いることができるのはもちろんのこと、製膜工程での安定性や造膜性、物性の均一性の観点から、ポリプロピレンにエチレン成分やブテン、ヘキセン、オクテンなどのα−オレフィン成分を５質量％以下の範囲で共重合してもよい。なお、ポリプロピレンへのコモノマーの導入形態としては、ランダム共重合でもブロック共重合でもいずれでも構わない。 Of course, homopolypropylene resin can be used for the porous film, and from the viewpoint of stability in the film-forming process, film-forming property, and uniformity of physical properties, polypropylene can contain ethylene components, butene, hexene, octene, etc. You may copolymerize an alpha olefin component in 5 mass% or less. The form of the comonomer introduced into the polypropylene may be either random copolymerization or block copolymerization.
また、上記のポリプロピレン樹脂は０．５〜５質量％の範囲で高溶融張力ポリプロピレンを含有させることが製膜性向上の点で好ましい。高溶融張力ポリプロピレンとは高分子量成分や分岐構造を有する成分をポリプロピレン樹脂中に混合したり、ポリプロピレンに長鎖分岐成分を共重合させたりすることで溶融状態での張力を高めたポリプロピレン樹脂であるが、中でも長鎖分岐成分を共重合させたポリプロピレン樹脂を用いることが好ましい。この高溶融張力ポリプロピレンは市販されており、たとえば、Ｂａｓｅｌｌ社製ポリプロピレン樹脂ＰＦ８１４、ＰＦ６３３、ＰＦ６１１やＢｏｒｅａｌｉｓ社製ポリプロピレン樹脂ＷＢ１３０ＨＭＳ、Ｄｏｗ社製ポリプロピレン樹脂Ｄ１１４、Ｄ２０６を用いることができる。 Moreover, it is preferable that said polypropylene resin contains a high melt tension polypropylene in 0.5-5 mass% at the point of film forming property improvement. High melt tension polypropylene is a polypropylene resin whose tension in the molten state is increased by mixing a high molecular weight component or a component having a branched structure into the polypropylene resin or by copolymerizing a long-chain branched component with polypropylene. However, among these, it is preferable to use a polypropylene resin copolymerized with a long chain branching component. This high melt tension polypropylene is commercially available. For example, polypropylene resins PF814, PF633, and PF611 manufactured by Basell, polypropylene resin WB130HMS manufactured by Borealis, and polypropylene resins D114 and D206 manufactured by Dow can be used.
多孔フィルムを構成するポリプロピレン樹脂には、延伸時の空隙形成効率を高め、孔径が拡大することで透気性が向上することから、ポリプロピレン樹脂にエチレン・α−オレフィン共重合体を１〜１０質量％含有せしめることが好ましい。ここで、エチレン・α−オレフィン共重合体としては直鎖状低密度ポリエチレンや超低密度ポリエチレンを挙げることができ、中でも、オクテン−１を共重合したエチレン・オクテン−１共重合体を好ましく用いることができる。このエチレン・オクテン−１共重合体は市販されている樹脂を用いることができる。 In the polypropylene resin constituting the porous film, the porosity forming efficiency at the time of stretching is increased, and the air permeability is improved by increasing the pore diameter. Therefore, 1 to 10% by mass of the ethylene / α-olefin copolymer is added to the polypropylene resin. It is preferable to make it contain. Here, examples of the ethylene / α-olefin copolymer include linear low density polyethylene and ultra-low density polyethylene. Among them, ethylene / octene-1 copolymer obtained by copolymerization of octene-1 is preferably used. be able to. A commercially available resin can be used for the ethylene-octene-1 copolymer.
本発明において基材に用いる多孔フィルムは少なくとも一軸方向に延伸されていることが好ましい。未延伸のフィルムを用いた場合、フィルムの空孔率や機械強度が不十分となる場合がある。多孔フィルムを少なくとも一軸方向に延伸する方法としては、加熱後、テンター法、ロール法、インフレーション法、又はこれらの組合せにより所定の倍率で延伸するのが好ましい。延伸は一軸延伸でも二軸延伸でもよい。二軸延伸の場合、同時二軸延伸、逐次延伸及び多段延伸（例えば同時二軸延伸及び逐次延伸の組合せ）のいずれでもよいが、生産性の観点から、逐次二軸延伸が好ましい。 In the present invention, the porous film used for the substrate is preferably stretched in at least a uniaxial direction. When an unstretched film is used, the porosity and mechanical strength of the film may be insufficient. As a method of stretching the porous film in at least a uniaxial direction, it is preferable to stretch the film at a predetermined ratio after heating by a tenter method, a roll method, an inflation method, or a combination thereof. The stretching may be uniaxial stretching or biaxial stretching. In the case of biaxial stretching, any of simultaneous biaxial stretching, sequential stretching, and multistage stretching (for example, a combination of simultaneous biaxial stretching and sequential stretching) may be used, but sequential biaxial stretching is preferable from the viewpoint of productivity.
本発明において基材に用いる多孔フィルムには、酸化防止剤、熱安定剤、帯電防止剤や無機あるいは有機粒子からなる滑剤、さらにはブロッキング防止剤や充填剤、非相溶性ポリマーなどの各種添加剤を含有させてもよい。特に、ポリオレフィン樹脂の熱履歴による酸化劣化を抑制する目的で、ポリオレフィン樹脂１００質量部に対して酸化防止剤を０．０１〜０．５質量部含有せしめることは好ましいことである。 The porous film used as the substrate in the present invention includes an antioxidant, a heat stabilizer, an antistatic agent, a lubricant composed of inorganic or organic particles, and various additives such as an antiblocking agent, a filler, and an incompatible polymer. May be included. In particular, it is preferable to contain 0.01 to 0.5 parts by mass of an antioxidant with respect to 100 parts by mass of the polyolefin resin in order to suppress oxidative degradation due to the thermal history of the polyolefin resin.
本発明において多孔質フィルムの基材に用いる多孔フィルムの透気抵抗は５０〜５００秒／１００ｍｌであることが好ましい。透気抵抗が５０秒／１００ｍｌ未満ではセパレータとした際に絶縁を保つことが困難となる場合がある。また、５００秒／１００ｍｌを超えると、多孔質フィルムの基材として用いた際、多孔質フィルムの透気抵抗が大きく、セパレータとして用いた場合の電池特性が悪化する傾向にある。多孔フィルムの透気抵抗は、より好ましくは８０〜４００秒／１００ｍｌ、さらに好ましくは１００〜３００秒／１００ｍｌである。 In the present invention, the air resistance of the porous film used as the porous film substrate is preferably 50 to 500 seconds / 100 ml. If the air permeability resistance is less than 50 seconds / 100 ml, it may be difficult to maintain insulation when the separator is used. On the other hand, if it exceeds 500 seconds / 100 ml, the air resistance of the porous film is large when used as a substrate of the porous film, and the battery characteristics when used as a separator tend to deteriorate. The air resistance of the porous film is more preferably 80 to 400 seconds / 100 ml, still more preferably 100 to 300 seconds / 100 ml.
本発明に用いる多孔フィルムは空孔率が５０％以上８０％未満であることが好ましく、６５％以上７５％未満であることがより好ましい。５０％未満では表面の孔の数が少なくなるため、多孔層を積層した際に多孔フィルムとの接着性が不十分となる場合がある。８０％以上の場合はセパレータ特性、および強度の観点から不十分となる場合がある。多孔フィルムの空孔率は多孔フィルムの比重（ρ）と樹脂（Ｂ）の比重（ｄ）より下記式より求めることができる。 The porous film used in the present invention preferably has a porosity of 50% or more and less than 80%, and more preferably 65% or more and less than 75%. If it is less than 50%, the number of pores on the surface will be small, so that the adhesion to the porous film may be insufficient when the porous layer is laminated. If it is 80% or more, it may be insufficient from the viewpoint of separator characteristics and strength. The porosity of the porous film can be obtained from the following formula from the specific gravity (ρ) of the porous film and the specific gravity (d) of the resin (B).
空孔率（％）＝〔（ｄ−ρ）／ｄ〕×１００
貫通孔、透気抵抗および空孔率をかかる好ましい範囲に制御する方法としては、樹脂（Ｂ）にポリプロピレン樹脂を用いた場合、エチレン・α−オレフィン共重合体を前述した特定比率で混合した樹脂を用いることで達成できる。さらに、後述する特定の二軸延伸条件を採用することにより効果的に達成することができる。
Porosity (%) = [(d−ρ) / d] × 100
As a method for controlling the through-hole, air permeability resistance and porosity to such a preferable range, when polypropylene resin is used for the resin (B), a resin in which an ethylene / α-olefin copolymer is mixed at the specific ratio described above. This can be achieved by using Furthermore, it can achieve effectively by adopting specific biaxial stretching conditions described later.
本発明に用いる多孔フィルムは、表面孔径について、０．０１μｍ以上０．５μｍ未満の孔径の孔の数（Ａ）と０．５μｍ以上１０μｍ未満の孔径の孔の数（Ｂ）の比率である（Ａ）／（Ｂ）の値が０．１〜４であることが好ましく、０．４〜３であることがより好ましい。（Ａ）／（Ｂ）の値が０．１より小さいと、多孔フィルムの表面に大径の開孔部分多すぎ、塗工時に塗剤が開孔部に入り込みすぎるため透気性が低下する場合がある。また（Ａ）／（Ｂ）の値が４を超えると、多孔フィルムの表面に小径の開孔部の比率が多すぎ、塗工・乾燥時に後述する樹脂（Ａ）の一部が開孔部分に入り込みにくいため十分な接着性が発現しない場合や、孔の閉塞により透気性が低下する場合がある。 The porous film used in the present invention is the ratio of the number of holes having a pore diameter of 0.01 μm or more and less than 0.5 μm (A) to the number of holes having a pore diameter of 0.5 μm or more and less than 10 μm (B). The value of A) / (B) is preferably from 0.1 to 4, and more preferably from 0.4 to 3. When the value of (A) / (B) is smaller than 0.1, there are too many large-diameter apertures on the surface of the porous film, and the air permeability decreases because the coating agent enters the apertures too much during coating. There is. When the value of (A) / (B) exceeds 4, the ratio of small-diameter apertures on the surface of the porous film is too large, and a part of the resin (A) described later during coating / drying is an aperture portion. There are cases where sufficient adhesion is not exhibited because it is difficult to penetrate, and air permeability may be reduced due to blockage of the holes.
表面孔径をかかる好ましい範囲に制御する方法としては、上述のβ晶核剤を添加したポリプロプレン樹脂を延伸・多孔化することで達成することができる。 A method for controlling the surface pore diameter within such a preferable range can be achieved by stretching and making the polypropylene resin to which the above-mentioned β crystal nucleating agent is added.
多孔フィルムの表面孔径は走査型電子顕微鏡を用いて表面画像を撮影し、画像解析を行うことで確認できる。 The surface pore diameter of the porous film can be confirmed by taking a surface image using a scanning electron microscope and performing image analysis.
次に、上記のようにして得た多孔フィルムの少なくとも片面に多孔層を形成するが、その前に多孔フィルムと多孔層との接着性を向上させる目的で、多孔フィルム表面にコロナ放電処理など、易接着化のための表面処理を行うことが好ましい。表面処理としては、空気中、酸素雰囲気、窒素雰囲気などでのコロナ放電処理や、プラズマ処理等を挙げることができるが、簡便なコロナ放電処理が好ましい。 Next, a porous layer is formed on at least one surface of the porous film obtained as described above, but for the purpose of improving the adhesion between the porous film and the porous layer before that, corona discharge treatment on the porous film surface, etc. It is preferable to perform a surface treatment for easy adhesion. Examples of the surface treatment include corona discharge treatment in air, an oxygen atmosphere, a nitrogen atmosphere, plasma treatment, and the like, but simple corona discharge treatment is preferable.
本発明の多孔質フィルムは、上記した多孔フィルムの少なくとも片面に、耐熱粒子と樹脂（Ａ）とを含む多孔層が設けられている。多孔層を有することにより、多孔フィルムのみでは達成できない、高温での耐熱性を発現することができる。以下に当該多孔層について、詳しく説明する。 As for the porous film of this invention, the porous layer containing a heat resistant particle and resin (A) is provided in the at least single side | surface of an above described porous film. By having a porous layer, heat resistance at high temperature, which cannot be achieved only by a porous film, can be expressed. The porous layer will be described in detail below.
本発明の多孔質フィルムの多孔層に用いる耐熱粒子とは、粒子の形状が少なくとも２００℃まで保持される粒子をいう。形状が保持されるとは、常温での粒子のアスペクト比や平均粒子径が２００℃においても変化しないことを意味する。より好ましくは３００℃まで形状が保持され、さらに好ましくは３３０℃まで形状が保持される。すなわち粒子の融点、軟化点、熱分解温度、または体積変化を伴う相転移が上記温度まで起こらないことが好ましい。具体的には、融点を示さずかつ少なくとも３３０℃までは形状が保持される粒子として、無機化合物であればアルミナ、チタン酸カリウム、ウォラストナイト、ガラス繊維、酸化チタン（ルチル型）、炭酸カルシウム（カルサイト、アラゴナイト）等や、融点が２５０℃以上である熱可塑性樹脂または実質的に融点を示さない樹脂、たとえばポリフェニレンサルファイド、ポリエーテルエーテルケトン、ポリサルフォンや、ポリイミド、ポリアミドイミド、ポリエーテルイミドなどの窒化芳香族化合物の繊維状物が挙げられる。耐熱粒子は複数種を用いてもよく、その場合、同一種の粒子で異なる径や形状のものおよび／または異なる種類の粒子で異なる径や形状のものを用いてもよいが、同一種の粒子を複数種用いることが樹脂（Ａ）との結着性の観点からより好ましい。これらの中でも、電気化学的安定性および透気抵抗を好ましい範囲にできるといった観点から炭酸カルシウム、アルミナ、シリカが好ましく、分散性および樹脂（Ａ）との接着性の観点から炭酸カルシウムがより好ましい。 The heat-resistant particles used in the porous layer of the porous film of the present invention refers to particles whose particle shape is maintained at least up to 200 ° C. “Holding the shape” means that the aspect ratio and average particle diameter of the particles at room temperature do not change even at 200 ° C. More preferably, the shape is maintained up to 300 ° C, and still more preferably the shape is maintained up to 330 ° C. That is, it is preferable that the phase transition accompanied by the melting point, softening point, thermal decomposition temperature, or volume change of the particles does not occur up to the above temperature. Specifically, as inorganic particles, alumina, potassium titanate, wollastonite, glass fiber, titanium oxide (rutile type), calcium carbonate as particles that do not exhibit a melting point and retain their shape up to at least 330 ° C. (Calcite, aragonite), etc., thermoplastic resins having a melting point of 250 ° C. or higher, or resins having substantially no melting point, such as polyphenylene sulfide, polyether ether ketone, polysulfone, polyimide, polyamideimide, polyetherimide, etc. And a fibrous material of a nitroaromatic compound. A plurality of types of heat-resistant particles may be used, and in that case, particles of the same type having different diameters and shapes and / or different types of particles having different diameters and shapes may be used. It is more preferable to use a plurality of types from the viewpoint of binding properties with the resin (A). Among these, calcium carbonate, alumina, and silica are preferable from the viewpoint that the electrochemical stability and air permeability resistance can be within a preferable range, and calcium carbonate is more preferable from the viewpoint of dispersibility and adhesiveness to the resin (A).
本発明の多孔層に用いる耐熱粒子の平均粒子径は、表面積を増加させ、結着性を向上させる観点から、０．０５〜１０μｍであることが好ましく、より好ましくは０．１〜２．０μｍであり、さらに好ましくは０．１〜１．０μｍである。平均粒子径が０．０５μｍ未満では、耐熱粒子が多孔フィルムの開孔表面からフィルム内部に入り込み、多孔フィルムの透気性が低下する場合がある。一方、平均粒子径が１０μｍを超えると、耐熱粒子の表面積が小さくなるため結着性が劣る場合やが多孔層の厚みを制御できなくなる場合がある。 The average particle diameter of the heat-resistant particles used in the porous layer of the present invention is preferably 0.05 to 10 μm, more preferably 0.1 to 2.0 μm from the viewpoint of increasing the surface area and improving the binding property. More preferably, the thickness is 0.1 to 1.0 μm. When the average particle diameter is less than 0.05 μm, the heat resistant particles may enter the film from the surface of the porous film, and the air permeability of the porous film may be lowered. On the other hand, when the average particle diameter exceeds 10 μm, the surface area of the heat-resistant particles becomes small, so that the binding property may be inferior or the thickness of the porous layer may not be controlled.
なお、耐熱粒子の平均粒子径は多孔質フィルム中の耐熱粒子を測定することにより得られる値をいう。具体的には、多孔質フィルムの表面を、走査型電子顕微鏡を用いて観察することで確認できる。 In addition, the average particle diameter of a heat resistant particle means the value obtained by measuring the heat resistant particle in a porous film. Specifically, it can be confirmed by observing the surface of the porous film using a scanning electron microscope.
本発明の多孔質フィルムの多孔層に含まれる上記耐熱粒子の濃度は６０質量％以上９５質量％未満であることが好ましく、８０質量％以上９５質量％未満であることがより好ましい。６０質量％未満であると、多孔層の耐熱性が十分に発現せず、多孔質フィルムとした際に収縮が著しくなる場合や、多孔層形成による透気抵抗の悪化が著しくなり電池の出力特性が劣る場合がある。また、９５質量％以上の場合、耐熱粒子に対して後述する樹脂（Ａ）の量が少なくなり、十分に耐熱粒子同士を接着できず、平面性や耐熱性が悪化する場合がある。本発明の多孔質フィルムの多孔層に含まれる上記耐熱粒子の濃度は、多孔質フィルムより多孔層を剥離・回収し、これを粉末Ｘ線解析し耐熱粒子種を同定した後、燃焼分析により有機成分を除去後の質量から無機元素の含有量を算出することで求めることができる。 The concentration of the heat-resistant particles contained in the porous layer of the porous film of the present invention is preferably 60% by mass or more and less than 95% by mass, and more preferably 80% by mass or more and less than 95% by mass. When the content is less than 60% by mass, the heat resistance of the porous layer is not sufficiently exhibited, and when the porous film is formed, the shrinkage becomes significant, or the air resistance due to the formation of the porous layer is remarkably deteriorated. May be inferior. Moreover, in the case of 95 mass% or more, the amount of the resin (A) described later with respect to the heat-resistant particles decreases, the heat-resistant particles cannot be sufficiently bonded to each other, and the flatness and heat resistance may be deteriorated. The concentration of the heat-resistant particles contained in the porous layer of the porous film of the present invention is determined by peeling and collecting the porous layer from the porous film, analyzing the powder X-rays and identifying the heat-resistant particle species, and then analyzing the organic layer by combustion analysis. It can obtain | require by calculating content of an inorganic element from the mass after removing a component.
本発明の多孔質フィルムの多孔層に用いる耐熱粒子は、アスペクト比（耐熱粒子の長径／耐熱粒子の短径）が１以上１．５未満であることが好ましく、１以上１．３未満であることがより好ましい。アスペクト比が１．５未満の粒子を用いることで、多孔層中単位体積当りの耐熱粒子の充填率が高くなることから、耐熱粒子間の距離を短くでき、樹脂（Ａ）による耐熱粒子間の結着性を向上できる。また、単位体積当りの表面積も増加することから樹脂（Ａ）と耐熱粒子間の結着性も改善できることから、多孔層からの粒子の脱落や基材からの多孔層の剥離を抑制することができる。また、結着性の改善により、多孔層の強度が増すことから、多孔質フィルムが加熱された際の耐熱性も向上する。上述する範囲のアスペクト比の耐熱粒子を用いる場合、耐熱粒子の種類としては同一種または２種以上の何れでもよいが、同一種であることが樹脂（Ａ）との結着性の観点からより好ましい。 The heat-resistant particles used in the porous layer of the porous film of the present invention preferably have an aspect ratio (major axis of the heat-resistant particles / minor axis of the heat-resistant particles) of 1 or more and less than 1.5, preferably 1 or more and less than 1.3. It is more preferable. By using particles having an aspect ratio of less than 1.5, the filling rate of the heat-resistant particles per unit volume in the porous layer is increased, so that the distance between the heat-resistant particles can be shortened and the heat-resistant particles between the resin (A) can be reduced. The binding property can be improved. In addition, since the surface area per unit volume is increased, the binding property between the resin (A) and the heat-resistant particles can be improved, so that the dropping of the particles from the porous layer and the peeling of the porous layer from the substrate can be suppressed. it can. Further, since the strength of the porous layer is increased by improving the binding property, the heat resistance when the porous film is heated is also improved. When using heat-resistant particles having an aspect ratio in the above-described range, the heat-resistant particles may be the same type or two or more types, but the same type is more preferable from the viewpoint of binding properties with the resin (A). preferable.
多孔層中の耐熱粒子のアスペクト比は後述する手法を用いて確認することができる。 The aspect ratio of the heat-resistant particles in the porous layer can be confirmed using a method described later.
耐熱粒子間および多孔層−基材間の結着性は後述する手法にて評価することができる。 The binding property between the heat-resistant particles and between the porous layer and the substrate can be evaluated by a method described later.
本発明の多孔質フィルムの多孔層の厚み（塗工により形成する場合の塗工厚み（塗工・乾燥後の厚み））は、多孔質フィルムに耐熱性を付与する観点から１〜３０μｍであることが好ましく、より好ましくは３〜２５μｍであり、さらに好ましくは５〜２０μｍである。厚みが１μｍ未満であると、多孔質フィルムとした際に耐熱性が低くなる場合がある、また、厚みが３０μｍを超えると、多孔質フィルムを折り曲げた際に、亀裂や剥離が生じやすくなる。 The thickness of the porous layer of the porous film of the present invention (coating thickness when formed by coating (thickness after coating and drying)) is 1 to 30 μm from the viewpoint of imparting heat resistance to the porous film. More preferably, it is 3-25 micrometers, More preferably, it is 5-20 micrometers. When the thickness is less than 1 μm, the heat resistance may be lowered when a porous film is formed. When the thickness is more than 30 μm, cracks and peeling are likely to occur when the porous film is bent.
厚みをかかる好ましい範囲に制御する方法としては、後述する塗工方法を用いた際の塗剤の塗出量や搬送速度等を制御することで達成することができる。 As a method for controlling the thickness within such a preferable range, it can be achieved by controlling the coating amount of the coating agent, the conveying speed, and the like when the coating method described later is used.
多孔層の厚みは接触式の厚み計や多孔質フィルムの断面観察を行うことで確認することができる。 The thickness of the porous layer can be confirmed by performing a cross-sectional observation of a contact-type thickness meter or a porous film.
本発明の多孔質フィルムの多孔層に用いる樹脂（Ａ）とは、他の材料間（耐熱粒子間、耐熱粒子−基材間など）を結着させることができる材料（結着剤）を指す。 The resin (A) used for the porous layer of the porous film of the present invention refers to a material (binder) that can bind other materials (between heat-resistant particles, between heat-resistant particles and a substrate, etc.). .
本発明の多孔質フィルムの多孔層に用いる樹脂（Ａ）は、耐熱粒子間ならびに耐熱粒子−基材間の結着性を向上させる観点から、変性ポリオレフィンを用いる。変性ポリオレフィンを用いることで結着する界面の濡れ性を改善することができ、より強い結着性を発現することができる。ここで変性ポリオレフィンとは、オレフィン骨格としてプロピレン、エチレン、イソブチレン、１−ブテン、１−ペンテン、１−ヘキセン等の炭素数２〜６のオレフィン類にアクリレート共重合体や不飽和カルボン酸骨格を導入した樹脂を指す。中でも不飽和カルボン酸骨格を導入した変性ポリオレフィンが高い結着性を示す観点からより好ましい。不飽和カルボン酸骨格としては分子内に少なくとも１個のカルボキシル基または酸無水物基を有する化合物であり、アクリル酸、メタクリル酸、マレイン酸、無水マレイン酸、イタコン酸、無水イタコン酸、フマル酸、クロトン酸等のほか、不飽和ジカルボン酸のハーフエステル、ハーフアミド等が挙げられる。樹脂（Ａ）としては上記例示のものを１種単独で用いてもよく、２種以上を併用してもよい。 The resin (A) used for the porous layer of the porous film of the present invention uses a modified polyolefin from the viewpoint of improving the binding property between the heat-resistant particles and between the heat-resistant particles and the substrate. By using the modified polyolefin, the wettability of the binding interface can be improved, and a stronger binding property can be expressed. Here, the modified polyolefin refers to an acrylate copolymer or an unsaturated carboxylic acid skeleton introduced into an olefin having 2 to 6 carbon atoms such as propylene, ethylene, isobutylene, 1-butene, 1-pentene and 1-hexene as an olefin skeleton. Refers to the resin. Among these, a modified polyolefin into which an unsaturated carboxylic acid skeleton is introduced is more preferable from the viewpoint of showing high binding properties. The unsaturated carboxylic acid skeleton is a compound having at least one carboxyl group or acid anhydride group in the molecule, and includes acrylic acid, methacrylic acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, fumaric acid, In addition to crotonic acid and the like, unsaturated dicarboxylic acid half esters, half amides and the like can be mentioned. As the resin (A), those exemplified above may be used alone or in combination of two or more.
本発明の多孔質フィルムは各材料間（耐熱粒子間、耐熱粒子−基材間など）が樹脂（Ａ）の溶融により結着されていることが好ましい。樹脂（Ａ）の溶融によりこれらの材料間が結着されることで、多孔層と多孔フィルムの一部が一体化して強い結着力を示す。上記の効果により多孔層からの耐熱粒子の脱落や多孔層が多孔フィルムから剥離するのを抑制することができ、本発明の多孔質フィルムをセパレータとして用いた際に、電池の組立時に耐熱粒子の脱落による工程汚染や、フィルム走行時の多孔層の剥がれによる欠点が発生するのを抑制でき、電池の品位向上が可能となる。また、他の材料間が強固に決着することにより多孔層の耐熱性を向上させることができる。 In the porous film of the present invention, it is preferable that the respective materials (between the heat-resistant particles, between the heat-resistant particles and the base material) are bound by melting the resin (A). By binding these materials by melting the resin (A), a part of the porous layer and the porous film are integrated to show a strong binding force. Due to the above effects, the heat-resistant particles can be prevented from falling off from the porous layer and the porous layer from being peeled off from the porous film. When the porous film of the present invention is used as a separator, It is possible to suppress the occurrence of process contamination due to falling off and the occurrence of defects due to peeling of the porous layer during film running, and the quality of the battery can be improved. Moreover, the heat resistance of a porous layer can be improved by firmly fixing between other materials.
本発明の多孔質フィルムの多孔層に用いる樹脂（Ａ）は溶融による結着性を発現させる観点から、融点または軟化点は７０〜１２０℃であることが好ましく、８０〜１１０℃であることがより好ましい。融点または軟化点が７０℃より低いと多孔層に樹脂（Ａ）を添加して使用した際に、多孔質フィルムの耐熱性が低下する場合がある。また、融点または軟化点が１２０℃より高いと樹脂（Ａ）によって耐熱粒子間ならびに耐熱粒子−基材間を溶融結着させる際に高い温度での加工が必要となるため、多孔フィルムの収縮を引き起こし透気抵抗や平面性といった特性を悪化させる場合がある。樹脂（Ａ）の融点または軟化点は後述する手法にて確認することができる。 The resin (A) used for the porous layer of the porous film of the present invention preferably has a melting point or softening point of 70 to 120 ° C., and preferably 80 to 110 ° C., from the viewpoint of expressing the binding property by melting. More preferred. When the melting point or softening point is lower than 70 ° C., the heat resistance of the porous film may be lowered when the resin (A) is added to the porous layer. Also, if the melting point or softening point is higher than 120 ° C., it is necessary to process at a high temperature when the resin (A) melts and bonds between the heat-resistant particles and between the heat-resistant particles and the base material. In some cases, characteristics such as air resistance and flatness are deteriorated. The melting point or softening point of the resin (A) can be confirmed by a method described later.
本発明の多孔質フィルムの多孔層に用いる樹脂（Ａ）の多孔層中の濃度は、接着性の観点から耐熱粒子１００質量部に対して１〜３０質量部が好ましく、１〜２０質量部がより好ましく、５〜１５質量部がさらに好ましい。樹脂（Ａ）の濃度が１質量部を下回ると、耐熱粒子間および多孔層と基材間の接着力が不足し、粒子の脱落や多孔層の剥離が起きる場合がある。また、３０質量部を上回ると多孔層内部の孔を閉塞するため透気性が低下する場合がある。 The concentration of the resin (A) used in the porous layer of the porous film of the present invention in the porous layer is preferably 1 to 30 parts by mass, and 1 to 20 parts by mass with respect to 100 parts by mass of the heat-resistant particles from the viewpoint of adhesiveness. More preferred is 5 to 15 parts by mass. When the concentration of the resin (A) is less than 1 part by mass, the adhesion between the heat-resistant particles and between the porous layer and the substrate is insufficient, and the particles may fall off or the porous layer may peel off. Moreover, when it exceeds 30 mass parts, since the hole inside a porous layer is obstruct | occluded, air permeability may fall.
本発明の多孔質フィルムにおいて、多孔層を形成するために使用する塗液には塗剤の粘度を塗工可能な範囲にする増粘効果と、耐熱粒子表面に吸着して塗料組成物中で耐熱粒子を分散安定化する機能を付与できる観点から、多孔層にセルロースおよび／またはセルロース塩を含むことが好ましい。セルロースおよび／またはセルロース塩の具体例としてはヒドロキシエチルセルロース、ヒドロキシプロピルセルロース、メチルセルロース、カルボキシメチルセルロースおよびこれらのナトリウム塩、アンモニウム塩などが挙げられる。なかでも、カルボキシメチルセルロース、その塩、ヒドロキシエチルセルロースおよびその塩からなる群から選択される少なくとも１種を含むことが特に好ましい。 In the porous film of the present invention, the coating liquid used to form the porous layer has a thickening effect that makes the viscosity of the coating within the applicable range, and adsorbs on the surface of the heat-resistant particles in the coating composition. From the viewpoint of imparting a function of dispersing and stabilizing the heat-resistant particles, it is preferable that the porous layer contains cellulose and / or a cellulose salt. Specific examples of cellulose and / or cellulose salt include hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, carboxymethyl cellulose, and sodium and ammonium salts thereof. Especially, it is especially preferable that at least 1 sort (s) selected from the group which consists of carboxymethylcellulose, its salt, hydroxyethylcellulose, and its salt is included.
本発明の多孔質フィルムの耐熱粒子間の結着性は、多孔層の表面をロールと接触するようにしてフィルム走行試験を実施した際の摩擦係数μｋの変化率Δμｋによって評価できる。 The binding property between the heat-resistant particles of the porous film of the present invention can be evaluated by the rate of change Δμk of the coefficient of friction μk when the film running test is performed with the surface of the porous layer in contact with the roll.
本発明において、多孔層の表面をロールと接触するようにしてフィルム走行試験を実施した際の摩擦係数μｋの変化率Δμｋは５００％未満が好ましく３００％未満がより好ましい。摩擦係数μｋはテープ走行性試験機でフィルムを走行させ、下記式より算出する。 In the present invention, the rate of change Δμk of the friction coefficient μk when the film running test is carried out with the surface of the porous layer in contact with the roll is preferably less than 500%, more preferably less than 300%. The coefficient of friction μk is calculated from the following equation by running the film with a tape running tester.
μｋ＝２／πｌｎ（Ｔ２／Ｔ１）
ここで、Ｔ１は入側張力、Ｔ２は出側張力である。
μk = 2 / πln (T2 / T1)
Here, T1 is the entry side tension and T2 is the exit side tension.
摩擦係数μｋの変化率Ｋ（％）はフィルム走行１回目と５０回目の摩擦係数μｋを下記式に代入し、算出する。 The rate of change K (%) of the coefficient of friction μk is calculated by substituting the coefficient of friction μk for the first and 50th film runs into the following equation.
変化率Ｋ（％）＝（走行５０回目の摩擦係数／走行１回目の摩擦係数）×１００
変化率Ｋが５００％以上になると、フィルム走行時に耐熱粒子の脱落が生じ、白粉が発生することがある。耐熱粒子の脱落は多孔質フィルムをセパレータとして使用した際、電池の組立工程の歩留まりや異物混入などの不良を引き起こす場合がある。
Rate of change K (%) = (Friction coefficient at the 50th run / Friction coefficient at the first run) × 100
When the rate of change K is 500% or more, the heat-resistant particles may fall off during film running, and white powder may be generated. When the porous film is used as a separator, the removal of the heat-resistant particles may cause defects such as the yield of the battery assembly process and contamination with foreign matter.
変化率Ｋを好ましい範囲とするためには、後述する結着剤を用いることで達成できる。 In order to make change rate K into a preferable range, it can achieve by using the binder mentioned later.
本発明の多孔質フィルムの多孔層−多孔フィルム間の結着性は、多孔質フィルムを多孔層／多孔フィルム界面にて剥離した際の剥離強度で評価できる。 The binding property between the porous layer and the porous film of the porous film of the present invention can be evaluated by the peel strength when the porous film is peeled off at the porous layer / porous film interface.
この剥離強度は、多孔フィルムと多孔層の結着力の指標であり、剥離強度が高いほど樹脂（Ａ）による耐熱粒子−基材間ならびに多孔層中の耐熱粒子間の結着力が高いことを示す。剥離強度は後述する方法にて評価できる。 This peel strength is an index of the binding force between the porous film and the porous layer, and the higher the peel strength, the higher the binding force between the heat-resistant particles and the substrate due to the resin (A) and between the heat-resistant particles in the porous layer. . The peel strength can be evaluated by the method described later.
本発明の多孔質フィルムは多孔層／多孔フィルム界面にて剥離することができる。多孔層／多孔フィルム界面にて剥離した際の剥離強度は２５〜５００ｇ／２５ｍｍ幅であることが好ましく、５０〜５００ｇ／２５ｍｍ幅であることがより好ましい。剥離強度が２５ｇ／２５ｍｍ未満では、多孔質フィルムより多孔層が剥離しやすく、多孔質フィルムをセパレータとして使用した際に、切断・スリット工程において部分的な剥がれが発生する場合がある。剥離強度が５００ｇ／２５ｍｍ幅を超えると、多孔質フィルムをセパレータとして使用した電池が発熱した際に、多孔フィルムと多孔層の結着性が強すぎるため、多孔フィルムの収縮・溶融により多孔層の形状維持が困難になる場合がある。 The porous film of the present invention can be peeled off at the porous layer / porous film interface. The peel strength at the time of peeling at the porous layer / porous film interface is preferably 25 to 500 g / 25 mm width, more preferably 50 to 500 g / 25 mm width. When the peel strength is less than 25 g / 25 mm, the porous layer is more easily peeled off than the porous film, and when the porous film is used as a separator, partial peeling may occur in the cutting / slit process. When the peel strength exceeds 500 g / 25 mm width, when the battery using the porous film as a separator generates heat, the binding property between the porous film and the porous layer is too strong. It may be difficult to maintain the shape.
剥離強度を好ましい範囲とするためには、表面孔径を好ましい範囲とすること、および／または後述する結着剤を用いることで達成できる。 In order to make the peel strength within a preferable range, it can be achieved by making the surface pore diameter into a preferable range and / or using a binder described later.
本発明において多孔質フィルムの透気抵抗は５０〜５００秒／１００ｍｌであることが好ましい。透気抵抗が５０秒／１００ｍｌ未満では電極間の絶縁が十分に保てず、安全性に劣る場合がある。また、５００秒／１００ｍｌを超えると多孔質フィルムをセパレータとして用いた際の電池の出力特性が悪化する傾向にある。多孔質フィルムの透気抵抗は、用途にもよるが、好ましくは８０〜４５０秒／１００ｍｌ、より好ましくは８０〜３５０秒／１００ｍｌ、特に好ましくは８０〜２５０秒／１００ｍｌである。多孔質フィルムの透気抵抗を上記の範囲にする方法としては、多孔層に前述する耐熱粒子用いること、前述する多孔フィルムを基材として用いることで効率的に達成できる。透気抵抗は後述する手法にて評価できる。 In the present invention, the air resistance of the porous film is preferably 50 to 500 seconds / 100 ml. If the air permeability resistance is less than 50 seconds / 100 ml, the insulation between the electrodes cannot be sufficiently maintained, and the safety may be inferior. Moreover, when it exceeds 500 seconds / 100 ml, it exists in the tendency for the output characteristic of the battery at the time of using a porous film as a separator to deteriorate. The air resistance of the porous film is preferably 80 to 450 seconds / 100 ml, more preferably 80 to 350 seconds / 100 ml, and particularly preferably 80 to 250 seconds / 100 ml, although it depends on the application. As a method for setting the air resistance of the porous film within the above range, it can be efficiently achieved by using the above-mentioned heat-resistant particles in the porous layer and using the above-mentioned porous film as a substrate. The air resistance can be evaluated by a method described later.
本発明の多孔質フィルムにおいて、多孔層を形成する方法として、耐熱粒子や樹脂（Ａ）およびその他の組成物を含有する塗液を塗布する方法が好ましく採用される。塗布する方法としては、一般に行われるどのような方法を用いてもよいが、例えば、オキシラン環含有化合物をイオン交換水などに分散させて作成した塗液をリバースコート法、バーコート法、グラビアコート法、ロッドコート法、ダイコート法、スプレーコート法などの塗布方法によりフィルム上に塗布し、乾燥して多孔層とすればよい。また、塗液を調製する際には多孔層における耐熱粒子の偏在を防止するために分散剤などを適宜添加してもよい。 In the porous film of the present invention, as a method for forming the porous layer, a method of applying a coating solution containing heat-resistant particles, the resin (A) and other compositions is preferably employed. As a method of coating, any generally performed method may be used. For example, a coating solution prepared by dispersing an oxirane ring-containing compound in ion-exchanged water or the like is used as a reverse coating method, a bar coating method, or a gravure coating. A porous layer may be formed by coating on a film by a coating method such as a method, a rod coating method, a die coating method, or a spray coating method. Moreover, when preparing a coating liquid, you may add a dispersing agent etc. suitably in order to prevent uneven distribution of the heat-resistant particle | grains in a porous layer.
本発明の多孔質フィルムにおいて、多孔層を形成する塗工工程における乾燥温度は、樹脂（Ａ）を溶融結着させる観点から樹脂（Ａ）の融点または軟化点＋５℃以上１２０℃未満が好ましく、樹脂（Ａ）の融点または軟化点＋１０℃以上１２０℃未満がより好ましい。樹脂（Ａ）の融点または軟化点＋５℃を下回ると、樹脂（Ａ）が溶融または軟化しないため結着性に劣る場合や、多孔層の残存水分率が高くなり、電池のセパレータとして使用した際に不具合を生じる場合がある。また、１２０℃を超えると、基材の主成分である樹脂（Ｂ）の収縮が起こるため、平面性や透気性が低下する場合がある。 In the porous film of the present invention, the drying temperature in the coating step for forming the porous layer is preferably the melting point or softening point of the resin (A) + 5 ° C. or more and less than 120 ° C. from the viewpoint of melt-binding the resin (A). The melting point or softening point of the resin (A) + 10 ° C. or more and less than 120 ° C. is more preferable. When the melting point or softening point of the resin (A) is below + 5 ° C., the resin (A) does not melt or soften, so that the binding property is inferior, or the residual moisture content of the porous layer becomes high, and when used as a battery separator May cause problems. Moreover, since it will shrink | contract the resin (B) which is a main component of a base material when it exceeds 120 degreeC, planarity and air permeability may fall.
本発明の多孔質フィルムの多孔層は、熱分析において７０〜１２０℃に吸熱ピークが検出できる。上記の範囲に吸熱ピークが検出されることで、多孔層中に溶融による結着が可能な樹脂（Ａ）が含まれることが確認できる。吸熱ピークのより好ましい範囲は８０〜１１０℃である。 The porous layer of the porous film of the present invention can detect an endothermic peak at 70 to 120 ° C. in thermal analysis. By detecting the endothermic peak in the above range, it can be confirmed that the porous layer contains the resin (A) that can be bound by melting. A more preferable range of the endothermic peak is 80 to 110 ° C.
本発明の多孔質フィルムの多孔層は、熱分析において７０〜１２０℃に検出される吸熱ピークの融解熱量（ΔＨ）が０．０１Ｊ／ｇ以上１０Ｊ／ｇ未満である。吸熱ピークは樹脂（Ａ）の融点または軟化点を示し、ΔＨは樹脂（Ａ）濃度に比例する。ΔＨを上記の範囲にすることで、塗工の乾燥工程で樹脂（Ａ）を十分に溶融し耐熱粒子や多孔フィルムと結着せしめることができるとともに、溶融して多孔層および基材である多孔フィルム表面の開孔部を閉塞することがなく優れた透気性を維持することができる。ΔＨが０．０１Ｊ／ｇ未満であると樹脂（Ａ）の溶融による結着性が十分に発揮されず、耐熱粒子の脱落や多孔フィルムからの多孔層の剥離が起きる場合がある。また、１０Ｊ／ｇ以上であると、塗工の乾燥工程において樹脂（Ａ）が溶融した際に、樹脂（Ａ）の濃度が高いため多孔層および／または多孔フィルム表面の開孔部を閉塞する場合がある。吸熱ピークのより好ましい範囲は０．０１Ｊ／ｇ以上８Ｊ／ｇ未満、さらに好ましくは０．１Ｊ／ｇ以上５J／ｇ未満であり、さらに好ましくは０．１Ｊ／ｇ以上３Ｊ／ｇ未満である。ΔＨを上記の範囲にするには上述する樹脂（Ａ）を上述する濃度で用いることで達成できる。 In the porous layer of the porous film of the present invention, the heat of fusion (ΔH) of the endothermic peak detected at 70 to 120 ° C. in thermal analysis is 0.01 J / g or more and less than 10 J / g. The endothermic peak indicates the melting point or softening point of the resin (A), and ΔH is proportional to the resin (A) concentration. By setting ΔH within the above range, the resin (A) can be sufficiently melted and bonded to the heat-resistant particles and the porous film in the coating drying step, and the porous layer and the base material can be melted to be porous. Excellent air permeability can be maintained without blocking the opening on the film surface. When ΔH is less than 0.01 J / g, the binding property due to melting of the resin (A) is not sufficiently exhibited, and the heat-resistant particles may fall off or the porous layer may be peeled off from the porous film. Further, if it is 10 J / g or more, when the resin (A) is melted in the coating drying step, the pores on the porous layer and / or the porous film surface are closed because the concentration of the resin (A) is high. There is a case. A more preferable range of the endothermic peak is 0.01 J / g or more and less than 8 J / g, more preferably 0.1 J / g or more and less than 5 J / g, and further preferably 0.1 J / g or more and less than 3 J / g. ΔH can be achieved within the above range by using the above-mentioned resin (A) at the above-mentioned concentration.
吸熱ピークおよび融解熱量（ΔＨ）は後述する手法にて評価することができる。 The endothermic peak and the heat of fusion (ΔH) can be evaluated by the methods described later.
本発明の多孔質フィルムは１７０℃におけるフィルムの長手方向および幅方向の熱収縮率の平均値は１％より大きく２５％以下であることが好ましく、１％より大きく１５％以下であることがより好ましく、１％より大きく１０％以下であることがさらに好ましい。１７０℃におけるフィルムの長手方向および幅方向の熱収縮率の平均値が２５％より大きいと電池のセパレータとして使用した際に、発生した熱によって基材である樹脂（Ｂ）が溶融破断した場合に基材に追従し収縮しやすいことを示すことから、多孔層の機能である短絡抑制の効果が低く、電池の安全性を保てない場合がある。また、収縮率は小さいほど好ましいが、熱可塑性樹脂を用いる場合、１％以下は実現が困難である。１７０℃におけるフィルムの長手方向および幅方向の熱収縮率の平均値を上記の範囲にするには前述する粒子と樹脂（Ａ）を多孔層に含有させることで効果的に達成できる。 In the porous film of the present invention, the average value of the thermal shrinkage in the longitudinal direction and the width direction of the film at 170 ° C. is preferably more than 1% and not more than 25%, more preferably more than 1% and not more than 15%. Preferably, it is more than 1% and 10% or less. When the average value of the thermal shrinkage in the longitudinal direction and the width direction of the film at 170 ° C. is larger than 25%, when the resin (B) as a base material is melted and broken by the generated heat when used as a battery separator, Since it shows that it tends to shrink following the base material, the effect of short circuit suppression, which is a function of the porous layer, is low, and the safety of the battery may not be maintained. Further, the smaller the shrinkage rate, the better. However, when a thermoplastic resin is used, 1% or less is difficult to realize. In order to make the average value of the heat shrinkage rate in the longitudinal direction and the width direction of the film at 170 ° C. within the above range, it can be effectively achieved by incorporating the aforementioned particles and the resin (A) in the porous layer.
１７０℃におけるフィルムの長手方向および幅方向の熱収縮率の平均値は後述する手法により評価できる。 The average value of the heat shrinkage rate in the longitudinal direction and the width direction of the film at 170 ° C. can be evaluated by the method described later.
本発明の多孔質フィルムは多孔層と多孔フィルムの接合部の一部が界面を持たず一体化していることが好ましい。換言すると、多孔層と多孔フィルムとが界面を形成することなく一体化している部分が存在していることが好ましい。一体化しているとは、電子顕微鏡等で観察した際に明確な境界をもたず接着されている状態をさす。接合部の一部が一体化することで結着性を高めることができ、多孔フィルムからの多孔層の剥離を抑制することができる。多孔質フィルムは多孔層と多孔フィルムの接合部の一部が界面を持たず一体化させるためには、上述する樹脂（Ａ）を上述する条件にて加熱乾燥し溶融・結着させることで達成できる。多孔層と多孔フィルムの接合部は後述する手法にて確認することができる。 In the porous film of the present invention, it is preferable that a part of the joint between the porous layer and the porous film has no interface and is integrated. In other words, it is preferable that there is a portion where the porous layer and the porous film are integrated without forming an interface. The term “integrated” refers to a state where there is no clear boundary when observed with an electron microscope or the like. When a part of the joint portion is integrated, the binding property can be improved, and peeling of the porous layer from the porous film can be suppressed. In order for the porous film and the porous layer and the porous film to be integrated without a part of the interface between the porous film and the porous film, the above-mentioned resin (A) is heat-dried under the above-mentioned conditions and melted and bound. it can. The joint between the porous layer and the porous film can be confirmed by the method described later.
本発明において、多孔層を形成するための塗剤とは、多孔層の組成物である耐熱粒子や樹脂（Ａ）などを分散媒に分散させたものを指す。ここで分散媒とは、水や有機溶媒を指す。有機溶媒としては、アセトンやエタノール、イソプロパノールなど、沸点が１００℃未満のものが好ましい。また、分散媒としては水や有機溶媒を単独で用いてもよいが、複数の有機溶媒を混合しても、水と有機溶媒を混合したものを用いてもよい。 In the present invention, the coating agent for forming a porous layer refers to a material obtained by dispersing heat-resistant particles, resin (A), or the like, which is a composition of the porous layer, in a dispersion medium. Here, the dispersion medium refers to water or an organic solvent. As the organic solvent, those having a boiling point of less than 100 ° C., such as acetone, ethanol, and isopropanol are preferable. In addition, as the dispersion medium, water or an organic solvent may be used alone, or a mixture of a plurality of organic solvents or a mixture of water and an organic solvent may be used.
上記塗剤の調合方法としては、多孔層の組成物と分散媒を分散装置にて混合・分散する方法が挙げられる。分散装置の具体的な例としては、ボールミル、ビーズミル、ジェットミル、ホモジナイザー、超音波分散機など挙げられるが、何れの手法を用いてもかまわない。 Examples of the method for preparing the coating agent include a method in which the composition of the porous layer and the dispersion medium are mixed and dispersed with a dispersing device. Specific examples of the dispersing device include a ball mill, a bead mill, a jet mill, a homogenizer, and an ultrasonic disperser, but any method may be used.
上記塗剤は、１０５℃で乾燥した際に得られる固形物の熱分析において７０〜１２０℃に検出される吸熱ピークの融解熱量（ΔＨ）が０．０１Ｊ／ｇ以上１０Ｊ／ｇ未満であることが好ましい。塗剤を乾燥した際に得られる固形物（不揮発成分）の吸熱ピークおよび融解熱量は、多孔層の耐熱ピークおよび融解熱量と一致する。ΔＨを上記の範囲にすることで、塗剤を塗工した後の乾燥工程で樹脂（Ａ）を十分に溶融し耐熱粒子や多孔フィルムと結着せしめるとともに、優れた透気性を発現する塗剤となる。吸熱ピークのより好ましい範囲は０．０１Ｊ／ｇ以上８Ｊ／ｇ未満、さらに好ましくは０．１Ｊ／ｇ以上５J／ｇ未満であり、さらに好ましくは０．１Ｊ／ｇ以上３Ｊ／ｇ未満である。 The coating material should have an endothermic peak melting heat (ΔH) of 0.01 J / g or more and less than 10 J / g detected at 70 to 120 ° C. in the thermal analysis of the solid obtained when dried at 105 ° C. Is preferred. The endothermic peak and heat of fusion of the solid matter (nonvolatile component) obtained when the coating is dried coincide with the heat resistant peak and heat of fusion of the porous layer. By making ΔH within the above range, the resin (A) is sufficiently melted in the drying step after the coating is applied, and is bonded to the heat-resistant particles and the porous film, and also exhibits excellent air permeability. It becomes. A more preferable range of the endothermic peak is 0.01 J / g or more and less than 8 J / g, more preferably 0.1 J / g or more and less than 5 J / g, and further preferably 0.1 J / g or more and less than 3 J / g.
以下に本発明の多孔質フィルムを構成する多孔フィルムの製造方法、および、多孔質フィルムの製造方法を具体的に説明する。なお、本発明の多孔質フィルムの基材に用いる多孔フィルムの製造方法はこれに限定されるものではないが、β晶法によるポリプロピレン多孔フィルムを例として説明する。 Below, the manufacturing method of the porous film which comprises the porous film of this invention, and the manufacturing method of a porous film are demonstrated concretely. In addition, although the manufacturing method of the porous film used for the base material of the porous film of this invention is not limited to this, the polypropylene porous film by (beta) crystal method is demonstrated as an example.
ポリプロピレン樹脂として、ＭＦＲ８ｇ／１０分の市販のホモポリプロピレン樹脂９４質量部、同じく市販のＭＦＲ２．５ｇ／１０分高溶融張力ポリプロピレン樹脂１質量部、さらにメルトインデックス１８ｇ／１０分の超低密度ポリエチレン樹脂５質量部にＮ，Ｎ’−ジシクロヘキシル−２，６−ナフタレンジカルボキシアミド０．２質量部を混合し、二軸押出機を使用して予め所定の割合で混合した原料を準備する。この際、溶融温度は２７０〜３００℃とすることが好ましい。 As a polypropylene resin, 94 parts by mass of a commercially available homopolypropylene resin with an MFR of 8 g / 10 minutes, 1 part by mass of a commercially available MFR of 2.5 g / 10 minutes with a high melt tension polypropylene resin, and an ultra low density polyethylene resin 5 with a melt index of 18 g / 10 minutes. A raw material is prepared by mixing 0.2 parts by mass of N, N′-dicyclohexyl-2,6-naphthalenedicarboxamide and 2 parts by mass in advance using a twin-screw extruder. At this time, the melting temperature is preferably 270 to 300 ° C.
次に、上記の混合原料を単軸の溶融押出機に供給し、２００〜２３０℃にて溶融押出を行う。そして、ポリマー管の途中に設置したフィルターにて異物や変性ポリマーなどを除去した後、Ｔダイよりキャストドラム上に吐出し、未延伸シートを得る。この際、キャストドラムは表面温度が１０５〜１３０℃であることが、キャストフィルムのβ晶形性能を高く制御する観点から好ましい。また、特にシートの端部の成形が後の延伸性に影響するので、端部にスポットエアーを吹き付けてドラムに密着させることが好ましい。なお、シート全体のドラム上への密着状態から必要に応じて全面にエアーナイフを用いて空気を吹き付ける方法や、静電印加法を用いてキャストドラムにポリマーを密着させてもよい。 Next, the mixed raw material is supplied to a single-screw melt extruder, and melt extrusion is performed at 200 to 230 ° C. And after removing a foreign material, a modified polymer, etc. with the filter installed in the middle of the polymer pipe | tube, it discharges on a cast drum from T-die, and an unstretched sheet is obtained. At this time, the surface temperature of the cast drum is preferably 105 to 130 ° C. from the viewpoint of controlling the β crystal form performance of the cast film to be high. In particular, since the forming of the end portion of the sheet affects the subsequent stretchability, it is preferable that the end portion is sprayed with spot air to adhere to the drum. Note that the polymer may be brought into close contact with the cast drum by a method of blowing air using an air knife over the entire surface from the contact state of the entire sheet on the drum, if necessary, or an electrostatic application method.
次に得られた未延伸シートを二軸配向させ、フィルム中に空孔を形成する。二軸配向させる方法としては、フィルム長手方向に延伸後幅方向に延伸、あるいは幅方向に延伸後長手方向に延伸する逐次二軸延伸法、またはフィルムの長手方向と幅方向をほぼ同時に延伸していく同時二軸延伸法などを用いることができるが、高透気性フィルムを得やすいという点で逐次二軸延伸法を採用することが好ましく、特に長手方向に延伸後、幅方向に延伸することが好ましい。 Next, the obtained unstretched sheet is biaxially oriented to form pores in the film. As a biaxial orientation method, the film is stretched in the longitudinal direction of the film and then stretched in the width direction, or the sequential biaxial stretching method in which the film is stretched in the width direction and then stretched in the longitudinal direction. The simultaneous biaxial stretching method can be used, but it is preferable to adopt the sequential biaxial stretching method in that it is easy to obtain a highly air-permeable film, and in particular, it is possible to stretch in the width direction after stretching in the longitudinal direction. preferable.
具体的な延伸条件としては、まず未延伸シートを長手方向に延伸する温度に制御する。温度制御の方法は、温度制御された回転ロールを用いる方法、熱風オーブンを使用する方法などを採用することができる。長手方向の延伸温度としては９０〜１３５℃、さらに好ましくは１００〜１２０℃の温度を採用することが好ましい。延伸倍率としては３〜６倍、より好ましくは４〜５．５倍である。次に、いったん冷却後、ステンター式延伸機にフィルム端部を把持させて導入する。そして、好ましくは１４０〜１５５℃に加熱して幅方向に５〜１２倍、より好ましくは６〜１０倍延伸を行う。なお、このときの横延伸速度としては３００〜５，０００％／分で行うことが好ましく、５００〜３，０００％／分であればより好ましい。ついで、そのままステンター内で熱固定を行うが、その温度は横延伸温度以上１６０℃以下が好ましい。さらに、熱固定時にはフィルムの長手方向および／もしくは幅方向に弛緩させながら行ってもよく、特に幅方向の弛緩率を５〜３５％とすることが、熱寸法安定性の観点から好ましい。 As specific stretching conditions, first, the temperature is controlled so that the unstretched sheet is stretched in the longitudinal direction. As a temperature control method, a method using a temperature-controlled rotating roll, a method using a hot air oven, or the like can be adopted. The stretching temperature in the longitudinal direction is preferably 90 to 135 ° C, more preferably 100 to 120 ° C. The stretching ratio is 3 to 6 times, more preferably 4 to 5.5 times. Next, after cooling, the end of the film is gripped and introduced into a stenter type stretching machine. And it heats to 140-155 degreeC preferably, and extends 5 to 12 times in the width direction, More preferably, it extends 6 to 10 times. The transverse stretching speed at this time is preferably 300 to 5,000% / min, more preferably 500 to 3,000% / min. Subsequently, heat setting is performed in the stenter as it is, and the temperature is preferably from the transverse stretching temperature to 160 ° C. Further, the heat setting may be performed while relaxing in the longitudinal direction and / or the width direction of the film, and in particular, the relaxation rate in the width direction is preferably 5 to 35% from the viewpoint of thermal dimensional stability.
上記製造方法によって作製した多孔フィルムに、耐熱粒子として炭酸カルシウム（アスペクト比１．２、平均粒子径０．５μｍ）１５質量％、樹脂（Ａ）として変性ポリエチレンエマルジョン（固形分濃度２０質量％）７．５質量％と、カルボキシメチルセルロース０．６５質量％と、イソプロピルアルコール１０質量％、イオン交換水６６．８５質量％をジェットミルにて混合・分散し、塗液を調製する。 In the porous film produced by the above production method, calcium carbonate (aspect ratio 1.2, average particle diameter 0.5 μm) 15 mass% as heat-resistant particles, modified polyethylene emulsion (solid content concentration 20 mass%) 7 as resin (A) 7 0.5% by mass, 0.65% by mass of carboxymethylcellulose, 10% by mass of isopropyl alcohol, and 66.85% by mass of ion-exchanged water are mixed and dispersed by a jet mill to prepare a coating solution.
この塗液を４時間攪拌した後にダイコーターを用いた塗布方法により多孔フィルム上に塗布し、１００℃で１分間乾燥させて、積層厚みが８〜３０μｍの多孔層とする。 After stirring this coating liquid for 4 hours, it is apply | coated on a porous film with the application | coating method using a die coater, and it is made to dry at 100 degreeC for 1 minute, and it is set as a porous layer whose laminated thickness is 8-30 micrometers.
本発明の多孔質フィルムは、優れた耐熱性、透気性、層間結着性を有していることから、蓄電デバイスのセパレータとして好適に使用することができる。 Since the porous film of the present invention has excellent heat resistance, air permeability, and interlayer binding property, it can be suitably used as a separator for an electricity storage device.
ここで、蓄電デバイスとしては、各種電池、特にリチウムイオン二次電池に代表される非水電解液二次電池や、リチウムイオンキャパシタなどの電気二重層キャパシタなどを挙げることができる。このような蓄電デバイスは充放電することで繰り返し使用することができるので、産業装置や生活機器、電気自動車やハイブリッド電気自動車などの電源装置として使用することができる。本発明の多孔質フィルムをセパレータとして使用した蓄電デバイスは、セパレータの優れた特性から産業機器や自動車の電源装置に好適に用いることができる。 Here, examples of the electricity storage device include various batteries, particularly non-aqueous electrolyte secondary batteries represented by lithium ion secondary batteries, and electric double layer capacitors such as lithium ion capacitors. Since such an electricity storage device can be repeatedly used by charging and discharging, it can be used as a power supply device for industrial devices, household equipment, electric vehicles, hybrid electric vehicles, and the like. The electricity storage device using the porous film of the present invention as a separator can be suitably used for industrial equipment and automobile power supply devices because of the excellent characteristics of the separator.
以下、実施例により本発明を詳細に説明する。なお、特性は以下の方法により測定、評価を行った。 Hereinafter, the present invention will be described in detail by way of examples. The characteristics were measured and evaluated by the following methods.
（１）多孔フィルムまたは多孔質フィルムに含まれる樹脂（Ｂ）のβ晶形成能
多孔フィルムまたは多孔質フィルムに含まれる樹脂（Ｂ）、または、多孔質フィルムおよび多孔フィルムそのもの５ｍｇを試料としてアルミニウム製のパンに採取し、示差走査熱量計（セイコー電子工業製ＲＤＣ２２０）を用いて測定した。まず、窒素雰囲気下で室温から２８０℃まで１０℃／分で昇温（ファーストラン）し、１０分間保持した後、３０℃まで１０℃／分で冷却する。５分保持後、再度１０℃／分で昇温（セカンドラン）した際に観測される融解ピークにについて、１４５〜１５７℃の温度領域にピークが存在する融解をβ晶の融解ピーク、１５８℃以上にピークが観察される融解をα晶の融解ピークとして、高温側の平坦部を基準に引いたベースラインとピークに囲まれる領域の面積から、それぞれの融解熱量を求め、α晶の融解熱量をΔＨα、β晶の融解熱量をΔＨβとしたとき、以下の式で計算される値をβ晶形成能とする。なお、融解熱量の校正はインジウムを用いて行った。
(1) β-crystal forming ability of resin (B) contained in porous film or porous film Resin (B) contained in porous film or porous film, or porous film and porous film itself as a sample made of aluminum And was measured using a differential scanning calorimeter (Seiko Denshi Kogyo RDC220). First, the temperature is raised from room temperature to 280 ° C. at 10 ° C./min (first run) in a nitrogen atmosphere, held for 10 minutes, and then cooled to 30 ° C. at 10 ° C./min. After holding for 5 minutes, the melting peak observed when the temperature is raised again at 10 ° C./min (second run) is the melting peak of the β crystal at 145 ° C. to 157 ° C., 158 ° C. The melting at which the peak is observed is defined as the melting peak of the α crystal, and the melting heat amount of the α crystal is obtained from the baseline and the area of the region surrounded by the peak drawn from the flat portion on the high temperature side. Is the ΔHα, and the heat of fusion of the β crystal is ΔHβ, the value calculated by the following formula is the β crystal forming ability. The heat of fusion was calibrated using indium.
β晶形成能（％） ＝ 〔ΔＨβ ／ （ΔＨα ＋ ΔＨβ）〕 × １００
上記で算出されたβ晶形成能について下記基準にて評価した。
β crystal forming ability (%) = [ΔHβ / (ΔHα + ΔHβ)] × 100
The β crystal formation ability calculated above was evaluated according to the following criteria.
Ａ：β晶形成能が４０〜９０％
Ｂ：β晶形成能が４０％未満
（２）多孔質フィルム、多孔フィルム、多孔層の厚み
走査型電子顕微鏡の試料台に固定した多孔質フィルムを、フィルム長手方向の断面がみえるようにスパッタリング装置を用いて減圧度１０−３Ｔｏｒｒ、電圧０．２５ＫＶ、電流１２．５ｍＡの条件にて１０分間、イオンエッチング処理を施して断面を切削した後、同装置にて該表面に金スパッタを施し、走査型電子顕微鏡を用いて倍率３，０００倍にて観察した。
A: β-crystal forming ability is 40 to 90%
B: β crystal forming ability is less than 40% (2) Thickness of porous film, porous film, and porous layer Sputtering apparatus so that a porous film fixed on a sample stage of a scanning electron microscope can be seen in the longitudinal section of the film Was subjected to ion etching treatment for 10 minutes under conditions of a degree of vacuum of 10 −3 Torr, a voltage of 0.25 KV, and a current of 12.5 mA, and the surface was cut with gold, and the surface was subjected to gold sputtering with the same apparatus. Observation was performed at a magnification of 3,000 using a scanning electron microscope.
観察により得られた画像より多孔質フィルム、多孔フィルム、多孔層の厚みを計測した。厚みの測定に用いるサンプルは長手方向に少なくとも５ｃｍ間隔で任意の場所の合計１０箇所を選定し、１０サンプルの計測値の平均をそのサンプルの多孔質フィルムの厚み（ｌａ）、多孔フィルムの厚み（ｌｂ）、多孔層厚み（ｌｃ）とした。 The thickness of the porous film, the porous film, and the porous layer was measured from the image obtained by observation. The sample used for the measurement of the thickness is selected from a total of 10 arbitrary positions at intervals of at least 5 cm in the longitudinal direction, and the average of the measured values of the 10 samples is the thickness of the porous film of the sample (la), the thickness of the porous film ( lb) and the porous layer thickness (lc).
（３）多孔フィルムの空孔率（Ｐａ）
多孔フィルムを５０ｍｍ×４０ｍｍの大きさに切取り試料とした。電子比重計（ミラージュ貿易（株）製ＳＤ−１２０Ｌ）を用いて、室温２３℃、相対湿度６５％の雰囲気にて比重の測定を行った。測定を３回行い、平均値をそのフィルムの比重ρとした。
(3) Porosity of porous film (Pa)
The porous film was cut into a size of 50 mm × 40 mm and used as a sample. Using an electronic hydrometer (SD-120L manufactured by Mirage Trading Co., Ltd.), the specific gravity was measured in an atmosphere at a room temperature of 23 ° C. and a relative humidity of 65%. The measurement was performed three times, and the average value was defined as the specific gravity ρ of the film.
次に、測定したフィルムを２８０℃、５ＭＰａで熱プレスを行い、その後、２５℃の水で急冷して、空孔を完全に消去したシートを作成した。このシートの比重を上記した方法で同様に測定し、平均値を樹脂の比重（ｄ）とした。なお、後述する実施例においては、いずれの場合も樹脂の比重ｄは０．９１であった。フィルムの比重と樹脂の比重から、以下の式により空孔率（Ｐａ）を算出した。 Next, the measured film was hot-pressed at 280 ° C. and 5 MPa, and then rapidly cooled with water at 25 ° C. to prepare a sheet from which pores were completely erased. The specific gravity of this sheet was measured in the same manner as described above, and the average value was defined as the specific gravity (d) of the resin. In the examples described later, the specific gravity d of the resin was 0.91 in any case. From the specific gravity of the film and the specific gravity of the resin, the porosity (Pa) was calculated by the following formula.
空孔率（Ｐａ）（％） ＝ 〔（ ｄ − ρ ） ／ ｄ 〕 × １００
（４）多孔フィルムの表面孔径および表面孔径比
走査型電子顕微鏡の試料台に固定した多孔フィルムの表面を、スパッタリング装置を用いて金スパッタを施し、走査型電子顕微鏡を用いて倍率１０，０００倍にて観察した。得られた観察像について画像解析装置を用いて表面の孔による空隙部分の形状の中での最大長さおよび最小長さを求め、その平均値をその孔の孔径とした。上記の操作で観察像中の１００個の孔について孔径を求めた。
Porosity (Pa) (%) = [(d−ρ) / d] × 100
(4) Surface pore diameter and surface pore diameter ratio of porous film The surface of the porous film fixed on the sample stage of the scanning electron microscope was subjected to gold sputtering using a sputtering apparatus, and the magnification was 10,000 times using a scanning electron microscope. Observed. With respect to the obtained observation image, the maximum length and the minimum length in the shape of the void portion due to the hole on the surface were obtained using an image analysis apparatus, and the average value was taken as the hole diameter of the hole. The hole diameter was calculated | required about 100 holes in an observation image by said operation.
求めた孔径のうち０．０１μｍ以上０．５μｍ未満の孔径の孔の数を（Ａ）、０．５μｍ以上１０μｍ未満の孔径の孔の数を（Ｂ）とし、下記式に当てはめ、そのサンプルの表面孔径比を算出した。 Of the obtained pore diameters, the number of holes having a diameter of 0.01 μm or more and less than 0.5 μm is (A), the number of holes having a diameter of 0.5 μm or more and less than 10 μm is (B), and the following formula is applied. The surface pore size ratio was calculated.
表面孔径比＝（Ａ）／（Ｂ）
（５）多孔フィルムおよび多孔質フィルムの透気抵抗
多孔フィルムまたは多孔質フィルムの１辺の長さ１５０ｍｍの正方形を切取り試料とし、ＪＩＳ Ｐ ８１１７（２００９）のＢ形のガーレー試験機を用いて、２３℃、相対湿度６５％にて、１００ｍｌの空気の透過時間を任意の３箇所について測定した。３箇所の透過時間の平均値を多孔フィルムまたは多孔質フィルムの透気抵抗とした。
Surface pore diameter ratio = (A) / (B)
(5) Air permeability resistance of porous film and porous film Using a B-shaped Gurley tester of JIS P 8117 (2009), using a porous film or a square with a length of 150 mm on one side of the porous film as a cut sample, At 23 ° C. and a relative humidity of 65%, the permeation time of 100 ml of air was measured at three arbitrary locations. The average value of the permeation times at three locations was taken as the air resistance of the porous film or porous film.
（６）耐熱粒子の平均粒子径
走査型電子顕微鏡の試料台に固定した多孔質フィルムの表面をスパッタリング装置を用いて金スパッタを施し、走査型電子顕微鏡ＳＥＭを用いて無作為に抽出した耐熱粒子を観察倍率２０，０００倍の写真を撮影する。その写真を画像解析ソフトウェア（（株）マウンテック製、ＭａｃＶｉｅｗ ｖｅｒ４．０）を用いて、耐熱粒子の断面投影像を作成した。
(6) Average particle diameter of heat-resistant particles The surface of the porous film fixed on the sample stage of the scanning electron microscope was subjected to gold sputtering using a sputtering apparatus, and the heat-resistant particles randomly extracted using a scanning electron microscope SEM Take a picture with an observation magnification of 20,000 times. A cross-sectional projection image of the heat-resistant particles was created from the photograph using image analysis software (MacView ver 4.0, manufactured by Mountec Co., Ltd.).
撮影した写真と断面投影像より、個々の耐熱粒子の形状の中での最大長さと最小長さを求め、下記式で定義される平均粒子径を算出した。平均粒子径は粒子１００個について求め、その平均を耐熱粒子の平均粒子径とした。 The maximum length and the minimum length in the shape of each heat-resistant particle were obtained from the photographed photograph and the cross-sectional projection image, and the average particle diameter defined by the following formula was calculated. The average particle diameter was determined for 100 particles, and the average was defined as the average particle diameter of the heat-resistant particles.
平均粒子径＝（最大長さ＋最小長さ）／２
（７）耐熱粒子のアスペクト比
走査型電子顕微鏡の試料台に固定した多孔質フィルムの表面をスパッタリング装置を用いて金スパッタを施し、走査型電子顕微鏡ＳＥＭを用いて無作為に抽出した耐熱粒子を観察倍率２０，０００倍の写真を撮影する。その写真を画像解析ソフトウェア（（株）マウンテック製、ＭａｃＶｉｅｗ ｖｅｒ４．０）を用いて、耐熱粒子の断面投影像を作成した。
Average particle diameter = (maximum length + minimum length) / 2
(7) Aspect ratio of heat-resistant particles The surface of the porous film fixed to the sample stage of the scanning electron microscope was subjected to gold sputtering using a sputtering device, and the heat-resistant particles randomly extracted using a scanning electron microscope SEM Take a photo with an observation magnification of 20,000. A cross-sectional projection image of the heat-resistant particles was created from the photograph using image analysis software (MacView ver 4.0, manufactured by Mountec Co., Ltd.).
撮影した写真と断面投影像より、個々の耐熱粒子の形状の中での最大長さと最小長さを求め、下記式で定義されるアスペクト比を算出した。アスペクト比は粒子１００個について求め、その平均を耐熱粒子のアスペクト比とした。 The maximum length and the minimum length in the shape of each heat-resistant particle were obtained from the photographed photograph and the cross-sectional projection image, and the aspect ratio defined by the following formula was calculated. The aspect ratio was determined for 100 particles, and the average was defined as the aspect ratio of the heat-resistant particles.
アスペクト比＝最大長さ／最小長さ
（８）熱特性（多孔層の吸熱ピークおよび融解熱量（ΔＨ））
多孔質フィルムの多孔層を積層した面を金属ヘラでこすり多孔層を剥離させ回収する。回収した多孔層を、５ｍｇを秤量し、試料としてアルミニウム製のパンに採取し、示差走査熱量計（セイコー電子工業製ＲＤＣ２２０）を用いて窒素雰囲気下で２５℃から２００℃まで１０℃／分で昇温し１０分間保持した後、３０℃まで１０℃／分で冷却し、融解曲線を得た。得られた曲線で昇温過程に観測される融解ピークにについて、７０〜１２０℃の温度領域に存在するピークを樹脂（Ａ）の融解ピークとした。またこの融解ピークの高温側の平坦部を基準に引いたベースラインとピークに囲まれる領域の面積から融解熱量（ΔＨ）を求めた。なお、融解熱量の校正はインジウムを用いて行った。
Aspect ratio = maximum length / minimum length (8) Thermal characteristics (endothermic peak and heat of fusion (ΔH) of porous layer)
The surface on which the porous layer of the porous film is laminated is rubbed with a metal spatula to peel off and collect the porous layer. 5 mg of the collected porous layer was weighed and collected as a sample in an aluminum pan, and was measured at 10 ° C./min from 25 ° C. to 200 ° C. under a nitrogen atmosphere using a differential scanning calorimeter (Seiko Denshi Kogyo RDC220). The temperature was raised and held for 10 minutes, and then cooled to 30 ° C. at 10 ° C./min to obtain a melting curve. Regarding the melting peak observed in the temperature rising process in the obtained curve, the peak existing in the temperature range of 70 to 120 ° C. was taken as the melting peak of the resin (A). Further, the heat of fusion (ΔH) was determined from the baseline drawn from the flat portion on the high temperature side of the melting peak and the area of the region surrounded by the peak. The heat of fusion was calibrated using indium.
（９）耐熱性（１７０℃におけるフィルムの長手方向および幅方向の熱収縮率の平均値）
セイコーインスツルメント社製ＴＭＡ／ＳＳ６０００を用いて、下記温度プログラムにて多孔質フィルムまたは多孔フィルムのフィルム長手方向および横手方向の収縮曲線を求め、得られた収縮曲線より１７０℃における収縮率を読み取った。測定は各方向についてｎ＝３で測定しその平均値を各々の方向の熱収縮率とした。
(9) Heat resistance (average value of heat shrinkage in the longitudinal direction and width direction of the film at 170 ° C.)
Using a TMA / SS6000 manufactured by Seiko Instruments Inc., the shrinkage curve in the longitudinal direction and the transverse direction of the porous film or the porous film was obtained by the following temperature program, and the shrinkage rate at 170 ° C. was read from the obtained shrinkage curve. It was. The measurement was performed at n = 3 in each direction, and the average value was defined as the heat shrinkage rate in each direction.
得られた各方向の熱収縮率を下記式に当てはめ、長手方向および幅方向の熱収縮率の平均値を算出し、下記基準にて評価した。 The obtained heat shrinkage rate in each direction was applied to the following formula, the average value of the heat shrinkage rate in the longitudinal direction and the width direction was calculated, and evaluated according to the following criteria.
フィルムの長手方向および幅方向の熱収縮率の平均値＝
（フィルム長手方向の熱収縮率＋フィルム横手方向の熱収縮率）／２
温度プログラム：２５℃→（５℃／ｍｉｎ）→２００℃（ｈｏｌｄ ５ｍｉｎ）
荷重：２ｇ
サンプルサイズ：サンプル長１５ｍｍ×幅４ｍｍ
評価基準
ＡＡ：１０％以下
Ａ：１０％より大きく１５％以下
Ｂ：１５％より大きく２５％以下
Ｃ：２５％より大きい
（１０）耐熱粒子の脱落
多孔質フィルムを幅１ｃｍのテープ状にスリットしたものをテープ走行性試験機ＴＢＴ−３００（（株）横浜システム研究所製）を使用し、２３℃、５０％ＲＨ雰囲気で走行させ、摩擦係数μｋを求めた。サンプルは多孔層側がガイドに接触するように設置した、ガイド径は６ｍｍφであり、ガイド材質はＳＵＳ２７（表面粗度０．２Ｓ）、巻き付け角は９０°走行速度は３．３ｃｍ／秒、繰り返し１〜５０回である。この測定によって得られた繰り返し回数１回目の摩擦係数（Ｋ１）と繰り返し回数５０回目の摩擦係数（Ｋ５０）を下記式に当てはめて算出した摩擦係数の変化率Ｋ（％）から繰り返し試験によるフィルム走行性を下記の基準で評価し、ＡおよびＢを合格とした。
Average value of thermal shrinkage in the longitudinal direction and width direction of the film =
(Heat shrinkage in the film longitudinal direction + heat shrinkage in the film transverse direction) / 2
Temperature program: 25 ° C. → (5 ° C./min)→200° C. (hold 5 min)
Load: 2g
Sample size: sample length 15mm x width 4mm
Evaluation criteria AA: 10% or less A: Greater than 10% and 15% or less B: Greater than 15% and 25% or less C: Greater than 25% (10) Removal of heat-resistant particles A porous film was slit into a tape shape having a width of 1 cm. Using a tape running tester TBT-300 (manufactured by Yokohama System Laboratory Co., Ltd.), the product was run in an atmosphere of 23 ° C. and 50% RH, and the friction coefficient μk was determined. The sample was installed so that the porous layer side was in contact with the guide, the guide diameter was 6 mmφ, the guide material was SUS27 (surface roughness 0.2S), the winding angle was 90 °, the running speed was 3.3 cm / sec, and the repetition was 1 ~ 50 times. The film running by the repetition test is obtained from the coefficient of change K (%) of the friction coefficient calculated by applying the friction coefficient (K1) of the first repetition number and the friction coefficient (K50) of the 50th repetition number obtained by this measurement to the following equation. The properties were evaluated according to the following criteria, and A and B were regarded as acceptable.
摩擦係数の変化率Ｋ（％）＝
繰り返し回数５０回目の摩擦係数（Ｋ５０）／繰り返し回数５０回目の摩擦係数（Ｋ１）×１００
評価基準
Ａ：変化率３００％未満
Ｂ：変化率３００％以上５００％未満
Ｃ：変化率５００％以上。
Friction coefficient change rate K (%) =
Friction coefficient at the 50th iteration (K50) / Friction coefficient at the 50th iteration (K1) × 100
Evaluation criteria A: Change rate of less than 300% B: Change rate of 300% or more and less than 500% C: Change rate of 500% or more.
（１１）剥離強度
多孔質フィルムをフィルム長手方向に２００ｍｍ、フィルム幅方向に２５ｍｍの短冊状にサンプリングし、その一端Ａをテープ等で剥離した後、１００ｍｍまで手で剥離し、剥離した２枚の端Ａを引っ張り試験機（島津製作所製“ＡＧ−１００Ａ”）のチャックにＪＩＳ Ｋ−７１２７（１９９９）に準じて固定し、速度１００ｍｍ／ｍｉｎで剥離させた時の、荷重を読み取るとともに、剥離箇所の破壊形態を目視にて確認した。上記測定を１つのサンプルにつき５点測定し、その平均について下記基準にて評価した。
(11) Peel strength The porous film was sampled in a strip shape of 200 mm in the film longitudinal direction and 25 mm in the film width direction, and one end A was peeled off with a tape or the like, and then peeled off to 100 mm by hand and peeled off. The end A is fixed to the chuck of a tensile tester (“AG-100A” manufactured by Shimadzu Corporation) according to JIS K-7127 (1999), and the load when peeled at a speed of 100 mm / min is read and the peeled portion The fracture form of was confirmed visually. The above measurement was performed at 5 points per sample, and the average was evaluated according to the following criteria.
ＡＡ：剥離強度が５０〜５００ｇ／２５ｍｍ幅かつ多孔層と多孔フィルムの界面で剥離
Ａ：剥離強度が２５ｇ／２５ｍｍ幅以上５０ｇ／ｍｍ幅未満かつ多孔層と多孔フィルムの界面で剥離
Ｂ：剥離強度が２５ｇ／２５ｍｍ幅以上５０ｇ／ｍｍ幅未満かつ多孔層の層内で破壊が発生
Ｃ：剥離強度が２５ｇ／２５ｍｍ幅未満で多孔層の層内で破壊が発生
（１２）多孔フィルムと多孔層の接合部の構造
走査型電子顕微鏡の試料台に固定した多孔質フィルムを、フィルム長手方向の断面がみえるようにスパッタリング装置を用いて減圧度１０−３Ｔｏｒｒ、電圧０．２５ＫＶ、電流１２．５ｍＡの条件にて１０分間、イオンエッチング処理を施して断面を切削した後、同装置にて該表面に金スパッタを施し、走査型電子顕微鏡を用いて倍率２５，０００倍にて多孔フィルムと多孔層の接合部の構造を観察した。
AA: Peel strength is 50 to 500 g / 25 mm width and peels at the interface between the porous layer and the porous film A: Peel strength is 25 g / 25 mm width and less than 50 g / mm width and peels at the interface between the porous layer and the porous film B: Peel strength 25 g / 25 mm width or more and less than 50 g / mm width and fracture occurs in the porous layer C: Peeling strength is less than 25 g / 25 mm width and fracture occurs in the porous layer (12) between the porous film and the porous layer Structure of junction part A porous film fixed on a sample stage of a scanning electron microscope is used with a sputtering apparatus so that a cross-section in the longitudinal direction of the film can be seen. The degree of vacuum is 10 −3 Torr, the voltage is 0.25 KV, and the current is 12.5 mA. After performing the ion etching treatment for 10 minutes under the conditions and cutting the cross section, the surface was subjected to gold sputtering using the same apparatus, and a scanning electron microscope was used at a magnification of 25, The structure of the joint between the porous film and the porous layer was observed at a magnification of 000.
切削は１サンプルについて５点のサンプリングを行い、その５点について観察を行った。 Cutting was performed by sampling 5 points per sample and observing the 5 points.
５点の観察像の内、図１のように多孔フィルムと多孔層の一部が一体化している箇所があるサンプルをＡ、一体化している箇所がないサンプルをＢと評価した。 Among the five observation images, a sample having a portion where the porous film and a part of the porous layer were integrated as shown in FIG. 1 was evaluated as A, and a sample having no integrated portion was evaluated as B.
（実施例２〜７、９、参考例１）
多孔フィルムの原料として、ポリプロピレン（住友化学（株）製、ＦＬＸ８０Ｅ４）を９４．４５質量％、エチレン−オクテン−１共重合体であるダウ・ケミカル製 Ｅｎｇａｇｅ８４１１（メルトインデックス：１８ｇ／１０分、以下、単にＰＥ−１と表記）を５質量％に加えて、β晶核剤であるＮ，Ｎ’−ジシクロヘキシル−２，６−ナフタレンジカルボキシアミド（新日本理化（株）製、Ｎｕ−１００、以下、単にβ晶核剤と表記）を０．３質量％、さらに酸化防止剤であるチバ・スペシャリティ・ケミカルズ製ＩＲＧＡＮＯＸ１０１０、ＩＲＧＡＦＯＳ１６８を、各々０．１５、０．１質量％をこの比率で混合されるように計量ホッパーから二軸押出機に原料供給し、３００℃で溶融混練を行い、ストランド状にダイから吐出して、２５℃の水槽にて冷却固化し、チップ状にカットしてチップ原料とした。
(Examples 2 to 7, 9 and Reference Example 1 )
As a raw material of the porous film, polypropylene (Sumitomo Chemical Co., Ltd., FLX80E4) is 94.45% by mass, Dow Chemical Engage 8411 (melt index: 18 g / 10 min, which is an ethylene-octene-1 copolymer), N, N′-dicyclohexyl-2,6-naphthalenedicarboxamide (Nippon Nippon Rika Co., Ltd., Nu-100), which is a β crystal nucleating agent, is added to 5% by mass of PE-1). , Simply expressed as β crystal nucleating agent), 0.35% by mass, and IRGANOX 1010 and IRGAFOS 168 manufactured by Ciba Specialty Chemicals, which are antioxidants, are mixed at a ratio of 0.15 and 0.1% by mass, respectively. The raw material is fed from the weighing hopper to the twin screw extruder, melt kneaded at 300 ° C., discharged from the die in a strand shape, and 25 And the cooled and solidified in a water bath, and a chip raw material and cut into chips.
このチップ原料を単軸押出機に供給して２２０℃で溶融押出を行い、２５μｍカットの焼結フィルターで異物を除去後、Ｔダイから１２０℃に表面温度を制御したキャストドラムに吐出し、ドラムに１５秒間接するようにキャストして厚み２００μｍ、幅２５０ｍｍの未延伸シートを得た。ついで、１２０℃に加熱したセラミックロールを用いて予熱を行いフィルムの長手方向に４．５倍延伸を行った。一旦冷却後、次にテンター式延伸機に端部をクリップで把持させて導入し、１４５℃で６倍に延伸した。そのまま、幅方向に１０％のリラックスを掛けながら１５５℃で６秒間の熱処理を行い、厚み１５μｍの多孔フィルムを得た。得られた多孔フィルムの透気抵抗は２００ｓ／１００ｍｌ、空孔率は７０％であった。 This chip raw material is supplied to a single screw extruder, melt extruded at 220 ° C., foreign matter is removed by a 25 μm cut sintered filter, and then discharged from a T die to a cast drum whose surface temperature is controlled at 120 ° C. The film was cast so as to be indirectly for 15 seconds to obtain an unstretched sheet having a thickness of 200 μm and a width of 250 mm. Next, preheating was performed using a ceramic roll heated to 120 ° C., and the film was stretched 4.5 times in the longitudinal direction of the film. After cooling, the end portion was introduced into a tenter type stretching machine by holding it with a clip, and stretched 6 times at 145 ° C. As it was, heat treatment was performed at 155 ° C. for 6 seconds while relaxing 10% in the width direction to obtain a porous film having a thickness of 15 μm. The resulting porous film had an air resistance of 200 s / 100 ml and a porosity of 70%.
次に、表２−１に示す処方にて組成物を計量・混合し、多孔層形成用の塗剤を調製した。これを上記多孔フィルムの片面（溶融押出時にドラムに接触した面、以下Ｄ面と表記）に、ダイコーターを用いて乾燥後の積層厚みが８μｍになるように塗液を塗布し、１００℃で１分間乾燥させて多孔層を形成し、多孔質フィルムを作製した。 Next, the composition was measured and mixed according to the formulation shown in Table 2-1, to prepare a coating material for forming a porous layer. This was coated on one side of the porous film (the surface in contact with the drum at the time of melt extrusion, hereinafter referred to as D side) using a die coater so that the laminated thickness after drying was 8 μm, at 100 ° C. A porous layer was formed by drying for 1 minute to produce a porous film.
（実施例８）
表２−１に示す処方にて組成物を計量・混合し、多孔層形成用の塗剤を調製した。実施例２の多孔フィルムの片面（溶融押出時にドラムに接触した面、以下Ｄ面と表記）に、ダイコーターを用いて乾燥後の積層厚みが８μｍになるように塗液を塗布し、６０℃で１分間乾燥させて多孔層を形成し、多孔質フィルムを作製した。
(Example 8)
The composition was weighed and mixed according to the formulation shown in Table 2-1, to prepare a coating material for forming a porous layer. On one side of the porous film of Example 2 (the surface in contact with the drum during melt extrusion, hereinafter referred to as the D surface), a coating solution was applied using a die coater so that the laminated thickness after drying was 8 μm, and 60 ° C. Was dried for 1 minute to form a porous layer, and a porous film was produced.
（比較例１）
実施例２で多孔層を形成する前の多孔フィルムをそのまま評価した。
(Comparative Example 1)
The porous film before forming the porous layer in Example 2 was evaluated as it was.
（比較例２〜４）
表２−２に示す処方にて組成物を計量・混合し、多孔層形成用の塗剤を調製した。実施例２の多孔フィルムの片面（溶融押出時にドラムに接触した面、以下Ｄ面と表記）に、ダイコーターを用いて乾燥後の積層厚みが８μｍになるように塗液を塗布し、１００℃で１分間乾燥させて多孔層を形成し、多孔質フィルムを作製した。
(Comparative Examples 2 to 4)
The composition was weighed and mixed according to the formulation shown in Table 2-2 to prepare a coating agent for forming a porous layer. On one side of the porous film of Example 2 (the surface in contact with the drum during melt extrusion, hereinafter referred to as the D surface), a coating solution was applied using a die coater so that the laminated thickness after drying was 8 μm, and 100 ° C. Was dried for 1 minute to form a porous layer, and a porous film was produced.
（塗剤に使用した組成物）
（粒子）
Ａ：炭酸カルシウム 宇部マテリアルズ（株）製“ＣＳ−４Ｎ Ａ”、平均粒子径０．５μｍ、アスペクト比１．２
Ｂ：炭酸カルシウム 宇部マテリアルズ（株）製“ＣＳ−３Ｎ Ｃ”、平均粒子径１．５μｍ、アスペクト比１．２
Ｃ：シリカ 電気化学工業（株）製“ＳＦＰ−３０”、平均粒子径０．７μｍ、アスペクト比１
Ｄ：アルミナ キンセイマテック（株）製“セラフ ２０２５”、平均粒子径２．０μｍ、アスペクト比１０
（結着剤）
Ａ：変性ポリエチレン水分散体、三井化学製、“ケミパールＭ−２００”、固形分濃度２０質量％水希釈品、樹脂の軟化点 ９０℃
Ｂ：変性ポリエチレン水分散体、三井化学製、“ケミパールＳ−２００”、固形分濃度２０質量％水希釈品、樹脂の軟化点 ７５℃
Ｃ：変性ポリエチレン水分散体、中京油脂（株）製、固形分濃度２０質量％、樹脂の軟化点 ９５℃
Ｄ：スチレンブタジエンラバー水分散体、ＪＳＲ（株）製“ＴＲＤ２００１”、固形分濃度２０質量％水希釈品、樹脂の軟化点 １２５℃
Ｅ：ＰＶＤＦ／アクリル分散体、アルケマ社製“カイナーアクアテック”、固形分濃度
２０質量％、樹脂の融点 １６０℃
Ｆ：ポリビニルアルコール水分散体、クラレ（株）“ＰＶＡ−１１７”、固形濃度分２０質量％、樹脂の融点 １５０℃
（増粘剤）
カルボキシメチルセルロース（ＣＭＣ） ダイセルファインケム（株）製“ダイセルＣＭＣ２２００”
実施例２〜９、参考例１、比較例１〜４のサンプルについての評価結果を表３−１、３−２に示す。
(Composition used for coating)
(particle)
A: Calcium carbonate “CS-4NA” manufactured by Ube Materials Co., Ltd., average particle size 0.5 μm, aspect ratio 1.2
B: Calcium carbonate “CS-3NC” manufactured by Ube Materials Co., Ltd., average particle size 1.5 μm, aspect ratio 1.2
C: Silica “SFP-30” manufactured by Denki Kagaku Kogyo Co., Ltd., average particle size 0.7 μm, aspect ratio 1
D: Alumina Kinsei Matec Co., Ltd. “Seraph 2025”, average particle size 2.0 μm, aspect ratio 10
(Binder)
A: Modified polyethylene aqueous dispersion, manufactured by Mitsui Chemicals, “Chemical M-200”, 20% by weight solid content water diluted product, softening point of resin 90 ° C.
B: Modified polyethylene aqueous dispersion, manufactured by Mitsui Chemicals, “Chemical S-200”, 20% by weight solid content diluted with water, softening point of resin 75 ° C.
C: Modified polyethylene aqueous dispersion, manufactured by Chukyo Yushi Co., Ltd., solid content concentration 20% by mass, resin softening point 95 ° C.
D: Styrene butadiene rubber aqueous dispersion, “TRD2001” manufactured by JSR Corporation, 20% by weight solid content diluted product with water, softening point of resin 125 ° C.
E: PVDF / acrylic dispersion, “Kayner Aquatech” manufactured by Arkema, solid content concentration 20% by mass, melting point of resin 160 ° C.
F: Polyvinyl alcohol aqueous dispersion, Kuraray Co., Ltd. “PVA-117”, solid concentration 20% by mass, resin melting point 150 ° C.
(Thickener)
Carboxymethylcellulose (CMC) "Daicel CMC2200" manufactured by Daicel Finechem Co., Ltd.
The evaluation results for the samples of Examples 2 to 9, Reference Example 1 and Comparative Examples 1 to 4 are shown in Tables 3-1 and 3-2.
本発明の多孔質フィルムは、多孔フィルムに多孔層を設けることで、安全性を有し、かつ優れたフィルム物性を有していることから、蓄電デバイス、特に非水電解質二次電池であるリチウムイオン電池のセパレータとして好適に用いることができる。 Since the porous film of the present invention is provided with a porous layer on the porous film and has safety and excellent film physical properties, it is an electric storage device, in particular lithium which is a non-aqueous electrolyte secondary battery. It can be suitably used as a separator for an ion battery.
１ 多孔層
２ 多孔フィルム
３ 多孔層と多孔フィルムの接合部
４ 多孔層と多孔フィルムが一体化している箇所
DESCRIPTION OF SYMBOLS 1 Porous layer 2 Porous film 3 Joint part of porous layer and porous film 4 Location where porous layer and porous film are integrated
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