JP2013194153A - Method for producing modified polyolefin microporous membrane - Google Patents
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- JP2013194153A JP2013194153A JP2012063294A JP2012063294A JP2013194153A JP 2013194153 A JP2013194153 A JP 2013194153A JP 2012063294 A JP2012063294 A JP 2012063294A JP 2012063294 A JP2012063294 A JP 2012063294A JP 2013194153 A JP2013194153 A JP 2013194153A
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- 229920000098 polyolefin Polymers 0.000 title claims abstract description 124
- 239000012982 microporous membrane Substances 0.000 title claims abstract description 102
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 18
- 239000002904 solvent Substances 0.000 claims abstract description 45
- 239000011148 porous material Substances 0.000 claims description 13
- 229920000642 polymer Polymers 0.000 claims description 12
- 150000001875 compounds Chemical class 0.000 claims description 11
- 239000012528 membrane Substances 0.000 claims description 11
- 238000002844 melting Methods 0.000 claims description 3
- 230000008018 melting Effects 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 abstract description 30
- 230000015572 biosynthetic process Effects 0.000 abstract description 2
- 238000000034 method Methods 0.000 description 30
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- 230000014759 maintenance of location Effects 0.000 description 11
- 230000035699 permeability Effects 0.000 description 11
- 239000000243 solution Substances 0.000 description 11
- VTYYLEPIZMXCLO-UHFFFAOYSA-L Calcium carbonate Chemical compound [Ca+2].[O-]C([O-])=O VTYYLEPIZMXCLO-UHFFFAOYSA-L 0.000 description 7
- 229920002134 Carboxymethyl cellulose Polymers 0.000 description 7
- 238000001035 drying Methods 0.000 description 7
- 239000001768 carboxy methyl cellulose Substances 0.000 description 6
- 235000010948 carboxy methyl cellulose Nutrition 0.000 description 6
- 239000008112 carboxymethyl-cellulose Substances 0.000 description 6
- 229920001577 copolymer Polymers 0.000 description 5
- 230000005484 gravity Effects 0.000 description 5
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- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 description 4
- VEXZGXHMUGYJMC-UHFFFAOYSA-N Hydrochloric acid Chemical compound Cl VEXZGXHMUGYJMC-UHFFFAOYSA-N 0.000 description 4
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- 239000011342 resin composition Substances 0.000 description 4
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- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 3
- XEKOWRVHYACXOJ-UHFFFAOYSA-N Ethyl acetate Chemical compound CCOC(C)=O XEKOWRVHYACXOJ-UHFFFAOYSA-N 0.000 description 3
- 229920000663 Hydroxyethyl cellulose Polymers 0.000 description 3
- 239000004354 Hydroxyethyl cellulose Substances 0.000 description 3
- KFZMGEQAYNKOFK-UHFFFAOYSA-N Isopropanol Chemical compound CC(C)O KFZMGEQAYNKOFK-UHFFFAOYSA-N 0.000 description 3
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 3
- 239000004699 Ultra-high molecular weight polyethylene Substances 0.000 description 3
- 239000007864 aqueous solution Substances 0.000 description 3
- 229910000019 calcium carbonate Inorganic materials 0.000 description 3
- -1 ethylene, propylene, 1-butene Chemical class 0.000 description 3
- 235000019447 hydroxyethyl cellulose Nutrition 0.000 description 3
- 238000005470 impregnation Methods 0.000 description 3
- 238000012423 maintenance Methods 0.000 description 3
- BDERNNFJNOPAEC-UHFFFAOYSA-N propan-1-ol Chemical compound CCCO BDERNNFJNOPAEC-UHFFFAOYSA-N 0.000 description 3
- 229920000785 ultra high molecular weight polyethylene Polymers 0.000 description 3
- QPFMBZIOSGYJDE-UHFFFAOYSA-N 1,1,2,2-tetrachloroethane Chemical compound ClC(Cl)C(Cl)Cl QPFMBZIOSGYJDE-UHFFFAOYSA-N 0.000 description 2
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 2
- WSSSPWUEQFSQQG-UHFFFAOYSA-N 4-methyl-1-pentene Chemical compound CC(C)CC=C WSSSPWUEQFSQQG-UHFFFAOYSA-N 0.000 description 2
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 description 2
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 description 2
- ZHNUHDYFZUAESO-UHFFFAOYSA-N Formamide Chemical compound NC=O ZHNUHDYFZUAESO-UHFFFAOYSA-N 0.000 description 2
- 239000004705 High-molecular-weight polyethylene Substances 0.000 description 2
- HBBGRARXTFLTSG-UHFFFAOYSA-N Lithium ion Chemical compound [Li+] HBBGRARXTFLTSG-UHFFFAOYSA-N 0.000 description 2
- 239000004952 Polyamide Substances 0.000 description 2
- 239000004962 Polyamide-imide Substances 0.000 description 2
- 229920002614 Polyether block amide Polymers 0.000 description 2
- 239000004697 Polyetherimide Substances 0.000 description 2
- 239000004698 Polyethylene Substances 0.000 description 2
- 239000003963 antioxidant agent Substances 0.000 description 2
- 230000003078 antioxidant effect Effects 0.000 description 2
- 238000009835 boiling Methods 0.000 description 2
- 229920002678 cellulose Polymers 0.000 description 2
- 239000001913 cellulose Substances 0.000 description 2
- 230000000052 comparative effect Effects 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 239000011256 inorganic filler Substances 0.000 description 2
- 229910003475 inorganic filler Inorganic materials 0.000 description 2
- 230000010220 ion permeability Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910001416 lithium ion Inorganic materials 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 239000011255 nonaqueous electrolyte Substances 0.000 description 2
- 239000004014 plasticizer Substances 0.000 description 2
- 229920002647 polyamide Polymers 0.000 description 2
- 229920002312 polyamide-imide Polymers 0.000 description 2
- 229920001601 polyetherimide Polymers 0.000 description 2
- 229920000573 polyethylene Polymers 0.000 description 2
- 239000000843 powder Substances 0.000 description 2
- 239000005060 rubber Substances 0.000 description 2
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 description 2
- 229920005992 thermoplastic resin Polymers 0.000 description 2
- QDOIZVITZUBGOQ-UHFFFAOYSA-N 1,1,2,2,3,3,4,4,4-nonafluoro-n,n-bis(1,1,2,2,3,3,4,4,4-nonafluorobutyl)butan-1-amine;1,1,2,2,3,3,4,4,4-nonafluoro-n-(1,1,2,2,3,3,4,4,4-nonafluorobutyl)-n-(trifluoromethyl)butan-1-amine Chemical compound FC(F)(F)C(F)(F)C(F)(F)C(F)(F)N(C(F)(F)F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)F.FC(F)(F)C(F)(F)C(F)(F)C(F)(F)N(C(F)(F)C(F)(F)C(F)(F)C(F)(F)F)C(F)(F)C(F)(F)C(F)(F)C(F)(F)F QDOIZVITZUBGOQ-UHFFFAOYSA-N 0.000 description 1
- WSLDOOZREJYCGB-UHFFFAOYSA-N 1,2-Dichloroethane Chemical compound ClCCCl WSLDOOZREJYCGB-UHFFFAOYSA-N 0.000 description 1
- IXPNQXFRVYWDDI-UHFFFAOYSA-N 1-methyl-2,4-dioxo-1,3-diazinane-5-carboximidamide Chemical compound CN1CC(C(N)=N)C(=O)NC1=O IXPNQXFRVYWDDI-UHFFFAOYSA-N 0.000 description 1
- FEIQOMCWGDNMHM-UHFFFAOYSA-N 5-phenylpenta-2,4-dienoic acid Chemical compound OC(=O)C=CC=CC1=CC=CC=C1 FEIQOMCWGDNMHM-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000001856 Ethyl cellulose Substances 0.000 description 1
- ZZSNKZQZMQGXPY-UHFFFAOYSA-N Ethyl cellulose Chemical compound CCOCC1OC(OC)C(OCC)C(OCC)C1OC1C(O)C(O)C(OC)C(CO)O1 ZZSNKZQZMQGXPY-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 229920000181 Ethylene propylene rubber Polymers 0.000 description 1
- YCKRFDGAMUMZLT-UHFFFAOYSA-N Fluorine atom Chemical compound [F] YCKRFDGAMUMZLT-UHFFFAOYSA-N 0.000 description 1
- 229920002845 Poly(methacrylic acid) Polymers 0.000 description 1
- 239000002202 Polyethylene glycol Substances 0.000 description 1
- 239000004734 Polyphenylene sulfide Substances 0.000 description 1
- 239000004372 Polyvinyl alcohol Substances 0.000 description 1
- 229920002125 Sokalan® Polymers 0.000 description 1
- 238000007605 air drying Methods 0.000 description 1
- 229910052791 calcium Inorganic materials 0.000 description 1
- 239000003990 capacitor Substances 0.000 description 1
- 229920003064 carboxyethyl cellulose Polymers 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 239000002270 dispersing agent Substances 0.000 description 1
- 239000003792 electrolyte Substances 0.000 description 1
- 125000002573 ethenylidene group Chemical group [*]=C=C([H])[H] 0.000 description 1
- 229920001249 ethyl cellulose Polymers 0.000 description 1
- 235000019325 ethyl cellulose Nutrition 0.000 description 1
- 229920001038 ethylene copolymer Polymers 0.000 description 1
- 238000001914 filtration Methods 0.000 description 1
- 239000010419 fine particle Substances 0.000 description 1
- 229910052731 fluorine Inorganic materials 0.000 description 1
- 239000011737 fluorine Substances 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- 150000004678 hydrides Chemical class 0.000 description 1
- 230000001771 impaired effect Effects 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 238000004898 kneading Methods 0.000 description 1
- 238000005259 measurement Methods 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
- 238000001471 micro-filtration Methods 0.000 description 1
- 239000012046 mixed solvent Substances 0.000 description 1
- 238000000465 moulding Methods 0.000 description 1
- 239000002736 nonionic surfactant Substances 0.000 description 1
- 230000000704 physical effect Effects 0.000 description 1
- 239000003495 polar organic solvent Substances 0.000 description 1
- 229920002492 poly(sulfone) Polymers 0.000 description 1
- 229920002401 polyacrylamide Polymers 0.000 description 1
- 239000004584 polyacrylic acid Substances 0.000 description 1
- 229920000728 polyester Polymers 0.000 description 1
- 229920000570 polyether Polymers 0.000 description 1
- 229920001223 polyethylene glycol Polymers 0.000 description 1
- 230000000379 polymerizing effect Effects 0.000 description 1
- 229920001955 polyphenylene ether Polymers 0.000 description 1
- 229920000069 polyphenylene sulfide Polymers 0.000 description 1
- 229920002689 polyvinyl acetate Polymers 0.000 description 1
- 239000011118 polyvinyl acetate Substances 0.000 description 1
- 229920002451 polyvinyl alcohol Polymers 0.000 description 1
- KUKFKAPJCRZILJ-UHFFFAOYSA-N prop-2-enenitrile;prop-2-enoic acid Chemical compound C=CC#N.OC(=O)C=C KUKFKAPJCRZILJ-UHFFFAOYSA-N 0.000 description 1
- 239000002994 raw material Substances 0.000 description 1
- 238000002407 reforming Methods 0.000 description 1
- 238000001223 reverse osmosis Methods 0.000 description 1
- 238000007650 screen-printing Methods 0.000 description 1
- 239000000661 sodium alginate Substances 0.000 description 1
- 235000010413 sodium alginate Nutrition 0.000 description 1
- 229940005550 sodium alginate Drugs 0.000 description 1
- RYYKJJJTJZKILX-UHFFFAOYSA-M sodium octadecanoate Chemical compound [Na+].CCCCCCCCCCCCCCCCCC([O-])=O RYYKJJJTJZKILX-UHFFFAOYSA-M 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 238000000108 ultra-filtration Methods 0.000 description 1
- 229920003169 water-soluble polymer Polymers 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
- Manufacture Of Porous Articles, And Recovery And Treatment Of Waste Products (AREA)
- Cell Separators (AREA)
Abstract
Description
本発明は、改質ポリオレフィン微多孔膜の製造方法に関する。更に詳しくは、非水電解液二次電池セパレータとして好適な改質ポリオレフィン微多孔膜の製造方法に関するものである。 The present invention relates to a method for producing a modified polyolefin microporous membrane. More specifically, the present invention relates to a method for producing a modified polyolefin microporous membrane suitable as a nonaqueous electrolyte secondary battery separator.
ポリオレフィン微多孔膜は、電池用セパレータ、電解コンデンサー用隔膜、各種フィルター、透湿防水衣料、逆浸透濾過膜、限外濾過膜及び精密濾過膜等の各種用途に用いられている。ポリオレフィン微多孔膜を電池用セパレータ、特にリチウムイオン電池用セパレータとして用いる場合、セパレータは正極と負極とを絶縁し続けることが必要であるため、特に高温時の寸法安定性の向上が求められている。 Polyolefin microporous membranes are used in various applications such as battery separators, electrolytic capacitor membranes, various filters, moisture-permeable waterproof clothing, reverse osmosis filtration membranes, ultrafiltration membranes, and microfiltration membranes. When a polyolefin microporous membrane is used as a battery separator, particularly a lithium ion battery separator, the separator needs to continue to insulate the positive electrode and the negative electrode. Therefore, improvement in dimensional stability especially at high temperatures is required. .
一般にポリオレフィン微多孔膜は、製膜時に熱処理を施すことにより、該熱処理での熱処理温度以下の温度範囲における寸法安定性の向上を図ることができるものの、熱処理温度を超える温度範囲における寸法安定性は向上しない。 In general, a polyolefin microporous film can be improved in dimensional stability in a temperature range below the heat treatment temperature by performing a heat treatment during film formation, but the dimensional stability in a temperature range exceeding the heat treatment temperature is Does not improve.
本発明者らは、上記課題を解決すべく鋭意研究を重ねた結果、ポリオレフィンからなる微多孔膜を２５℃における表面張力が２５ｍＮ／ｍ以上の溶媒で処理することで、熱処理温度を超える温度範囲におけるポリオレフィン微多孔膜の寸法安定を向上させることができることを見出し、本発明に至った。 As a result of intensive studies to solve the above-mentioned problems, the present inventors have processed a microporous membrane made of polyolefin with a solvent having a surface tension at 25 ° C. of 25 mN / m or more, so that the temperature range exceeds the heat treatment temperature. It has been found that the dimensional stability of the polyolefin microporous membrane can be improved, and the present invention has been achieved.
すなわち、本発明は、以下の発明に係るものである。
＜１＞ ポリオレフィンからなる微多孔膜（Ａ）に、２５℃における表面張力が２５ｍＮ／ｍ以上であって、かつポリオレフィンを溶解しない溶媒（Ｂ）を含浸させ、次いで溶媒（Ｂ）を除去することを特徴とする改質ポリオレフィン微多孔膜の製造方法。
＜２＞ 微多孔膜（Ａ）が、膜厚が８〜２５μｍ、空隙率が４０〜７０％、平均孔径が０．０５〜０．１５μｍであることを特徴とする前記＜１＞記載の改質ポリオレフィン微多孔膜の製造方法。
＜３＞ ポリオレフィンからなる微多孔膜（Ａ）に、以下の溶媒（Ｂ）と高分子化合物（Ｃ）とからなる溶液を含浸させて、次いで溶媒（Ｂ）を除去することを特徴とする改質ポリオレフィン微多孔膜の製造方法。
溶媒（Ｂ）：２５℃における表面張力が２５ｍＮ／ｍ以上であって、かつポリオレフィンを溶解しない溶媒。
＜４＞ 前記高分子化合物（Ｃ）が、融点が１８０℃以上の高分子化合物である前記＜３＞記載の改質ポリオレフィン微多孔膜の製造方法。
That is, the present invention relates to the following inventions.
<1> A microporous membrane (A) made of polyolefin is impregnated with a solvent (B) having a surface tension at 25 ° C. of 25 mN / m or more and not dissolving polyolefin, and then removing the solvent (B). A process for producing a modified polyolefin microporous membrane.
<2> The modified <1>, wherein the microporous membrane (A) has a thickness of 8 to 25 μm, a porosity of 40 to 70%, and an average pore size of 0.05 to 0.15 μm. For producing a porous polyolefin microporous membrane.
<3> A microporous membrane (A) made of polyolefin is impregnated with a solution consisting of the following solvent (B) and polymer compound (C), and then the solvent (B) is removed. For producing a porous polyolefin microporous membrane.
Solvent (B): A solvent having a surface tension at 25 ° C. of 25 mN / m or more and does not dissolve polyolefin.
<4> The method for producing a modified polyolefin microporous membrane according to <3>, wherein the polymer compound (C) is a polymer compound having a melting point of 180 ° C. or higher.
本発明によれば、ポリオレフィン微多孔膜に施された熱処理での熱処理温度を超える温度範囲においても、寸法安定性が向上した改質ポリオレフィン微多孔膜が得られる。 According to the present invention, a modified polyolefin microporous membrane having improved dimensional stability can be obtained even in a temperature range exceeding the heat treatment temperature in the heat treatment applied to the polyolefin microporous membrane.
以下、本発明について詳しく説明する。 The present invention will be described in detail below.
本発明の改質ポリオレフィン微多孔膜の製造方法（以下、本発明の製造方法ということがある。）は、ポリオレフィンからなる微多孔膜（Ａ）に、２５℃における表面張力が２５ｍＮ／ｍ以上であって、かつポリオレフィンを溶解しないる溶媒（Ｂ）を含浸させ、次いで溶媒（Ｂ）を除去することで、改質ポリオレフィン微多孔膜が得られる。ここで、改質とは、熱処理での熱処理温度を超える温度範囲における寸法安定性が向上することをいう。 The method for producing a modified polyolefin microporous membrane of the present invention (hereinafter sometimes referred to as the production method of the present invention) comprises a microporous membrane (A) made of polyolefin with a surface tension at 25 ° C. of 25 mN / m or more. A modified polyolefin microporous membrane is obtained by impregnating the solvent (B) that does not dissolve the polyolefin and then removing the solvent (B). Here, the reforming means that dimensional stability in a temperature range exceeding the heat treatment temperature in heat treatment is improved.
ポリオレフィンからなる微多孔膜（Ａ）（以下、ポリオレフィン微多孔膜（Ａ）ということがある。）は、その内部に連結した細孔を有す構造を有し、一方の面から他方の面に気体や液体が透過可能であるポリオレフィンを主成分とする微多孔膜である。 The microporous membrane (A) made of polyolefin (hereinafter sometimes referred to as polyolefin microporous membrane (A)) has a structure having pores connected to the inside thereof, and from one surface to the other surface. It is a microporous membrane mainly composed of polyolefin that is permeable to gas and liquid.
ポリオレフィン微多孔膜（Ａ）におけるポリオレフィン成分の割合は、全重量の５０体積％以上であることを必須とし、９０体積％以上であることが好ましく、９５％体積以上であることがより好ましい。 The proportion of the polyolefin component in the polyolefin microporous membrane (A) must be 50% by volume or more of the total weight, preferably 90% by volume or more, and more preferably 95% by volume or more.
ポリオレフィン微多孔膜（Ａ）のポリオレフィン成分には、重量平均分子量が５×１０５〜１５０×１０５の高分子量成分が含まれていることが好ましい。特にポリオレフィン微多孔膜（Ａ）のポリオレフィン成分として重量平均分子量１００万以上のポリオレフィン成分が含まれると、ポリオレフィン微多孔膜（Ａ）の強度が高くなるため好ましい。 The polyolefin component of the polyolefin microporous membrane (A) preferably contains a high molecular weight component having a weight average molecular weight of 5 × 10 5 to 150 × 10 5 . In particular, when a polyolefin component having a weight average molecular weight of 1 million or more is contained as the polyolefin component of the polyolefin microporous membrane (A), the strength of the polyolefin microporous membrane (A) is preferably increased.
ポリオレフィンとしては、例えば、エチレン、プロピレン、１−ブテン、４−メチル−１−ペンテン、１−ヘキセンなどを重合した高分子量の単独重合体又は共重合体が挙げられる。これらの中でもエチレンを主体とする重量平均分子量１００万以上の高分子量ポリエチレンが好ましい。 Examples of the polyolefin include a high molecular weight homopolymer or copolymer obtained by polymerizing ethylene, propylene, 1-butene, 4-methyl-1-pentene, 1-hexene and the like. Among these, high molecular weight polyethylene mainly having ethylene and having a weight average molecular weight of 1,000,000 or more is preferable.
ポリオレフィン微多孔膜（Ａ）の膜厚は通常８〜２５μｍであるが、１０μｍ以上が好ましく、１２μｍ以上がより好ましい。膜厚が小さすぎると正負極間の絶縁を保つことが困難なので好ましくない。また上限も２２μｍ以下が好ましく、２０μｍ以下がより好ましい。膜厚が大きすぎると、電池容量エネルギー密度が低くなるため好ましくない。 The film thickness of the polyolefin microporous membrane (A) is usually 8 to 25 μm, preferably 10 μm or more, and more preferably 12 μm or more. If the film thickness is too small, it is difficult to maintain insulation between the positive and negative electrodes. The upper limit is also preferably 22 μm or less, and more preferably 20 μm or less. An excessively large film thickness is not preferable because the battery capacity energy density is lowered.
ポリオレフィン微多孔膜（Ａ）の空隙率は通常４０〜７０％であるが、４５％以上が好ましく５０％以上がより好ましい。空隙率が低すぎるとイオン透過性が確保できないので好ましくない。また上限も６５％以下が好ましく、６０％以下がより好ましい。空隙率が高すぎるとセパレータの強度を十分に確保することが出来ないので好ましくない。 The porosity of the polyolefin microporous membrane (A) is usually 40 to 70%, preferably 45% or more, and more preferably 50% or more. If the porosity is too low, ion permeability cannot be secured, which is not preferable. The upper limit is also preferably 65% or less, and more preferably 60% or less. If the porosity is too high, it is not preferable because the separator cannot have sufficient strength.
ポリオレフィン微多孔膜（Ａ）の平均孔径は通常０．０５〜０．１５μｍであるが、０．０６μｍ以上が好ましく、０．０７μｍ以上がより好ましい。孔径が小さすぎると、イオン透過性が確保できないので好ましくない。また上限も０．１４μｍ以下が好ましく、０．１３μｍ以下がより好ましい。孔径が大きすぎると、溶媒処理乾燥時に表面張力が十分に機能せず、微多孔膜を改質できないため好ましくない。 The average pore size of the polyolefin microporous membrane (A) is usually 0.05 to 0.15 μm, preferably 0.06 μm or more, and more preferably 0.07 μm or more. If the pore diameter is too small, ion permeability cannot be secured, which is not preferable. The upper limit is preferably 0.14 μm or less, and more preferably 0.13 μm or less. If the pore diameter is too large, the surface tension does not sufficiently function during solvent treatment drying, and the microporous membrane cannot be modified, which is not preferable.
ポリオレフィン微多孔膜（Ａ）の透気度は、通常、ガーレー値で３０〜５００秒／１００ｃｃの範囲であり、好ましくは、５０〜３００秒／１００ｃｃの範囲である。 The air permeability of the polyolefin microporous membrane (A) is usually in the range of 30 to 500 seconds / 100 cc in terms of Gurley value, and preferably in the range of 50 to 300 seconds / 100 cc.
ポリオレフィン微多孔膜（Ａ）の製造方法は特に限定されるものではなく、例えば特開平７−２９５６３号公報に記載されたように、熱可塑性樹脂に可塑剤を加えてフィルム成形した後、該可塑剤を適当な溶媒で除去する方法や、特開平７−３０４１１０号公報に記載されたように、公知の方法により製造した熱可塑性樹脂からなるフィルムを用い、該フィルムの構造的に弱い非晶部分を選択的に延伸して微細孔を形成する方法が挙げられる。
例えば、ポリオレフィン微多孔膜（Ａ）が、超高分子量ポリエチレン及び重量平均分子量１万以下の低分子量ポリオレフィンを含むポリオレフィン樹脂から形成されてなる場合には、製造コストの観点から、以下に示すような方法により製造することが好ましい。
（１）超高分子量ポリエチレン１００重量部と、重量平均分子量１万以下の低分子量ポリオレフィン５〜２００重量部と、炭酸カルシウム等の無機充填剤１００〜４００重量部とを混練してポリオレフィン樹脂組成物を得る工程
（２）前記ポリオレフィン樹脂組成物を用いてシートを成形する工程
（３）工程（２）で得られたシート中から無機充填剤を除去する工程
（４）工程（３）で得られたシートを延伸する工程
（５）工程（４）で得られたシートを熱処理する工程
なお、ポリオレフィン微多孔膜（Ａ）については上記記載の特性を有する市販品を用いることができる。
The method for producing the polyolefin microporous membrane (A) is not particularly limited. For example, as described in JP-A-7-29563, a plasticizer is added to a thermoplastic resin to form a film. Using a film made of a thermoplastic resin produced by a known method as described in JP-A-7-304110 or a method of removing the agent with a suitable solvent, and a structurally weak amorphous part of the film And a method of forming fine holes by selectively stretching.
For example, when the polyolefin microporous membrane (A) is formed from an ultrahigh molecular weight polyethylene and a polyolefin resin containing a low molecular weight polyolefin having a weight average molecular weight of 10,000 or less, from the viewpoint of production cost, as shown below It is preferable to manufacture by a method.
(1) A polyolefin resin composition obtained by kneading 100 parts by weight of ultrahigh molecular weight polyethylene, 5 to 200 parts by weight of a low molecular weight polyolefin having a weight average molecular weight of 10,000 or less, and 100 to 400 parts by weight of an inorganic filler such as calcium carbonate. (2) The step of molding a sheet using the polyolefin resin composition (3) The step of removing the inorganic filler from the sheet obtained in the step (2) (4) The step (3) Step of stretching the sheet (5) Step of heat-treating the sheet obtained in the step (4) As the polyolefin microporous membrane (A), a commercially available product having the characteristics described above can be used.
ポリオレフィン微多孔膜（Ａ）は、本発明の目的を損なわない範囲で他の成分を含んでいてもよい。他の成分としては、例えば酸化防止剤、分散剤、可塑剤などが挙げられる。 The polyolefin microporous membrane (A) may contain other components as long as the object of the present invention is not impaired. Examples of other components include an antioxidant, a dispersant, and a plasticizer.
本発明の含浸とは、多孔質体の内部にまで液体を染み込ませることを意味する。すなわち、本発明においては、含浸処理によりポリオレフィン微多孔膜（Ａ）の細孔が実質的に溶媒（Ｂ）で満たされた状態になる。 The impregnation of the present invention means that the liquid is soaked into the porous body. That is, in the present invention, the pores of the polyolefin microporous membrane (A) are substantially filled with the solvent (B) by the impregnation treatment.
溶媒（Ｂ）は、２５℃での表面張力が２５ｍＮ／ｍ以上であって、かつポリオレフィンを溶解しない溶媒であれば特に制限は無い。溶媒（Ｂ）としては、例えばクロロホルム（２５℃での表面張力２６．７ｍＮ／ｍ）、四塩化炭素（同２６．４ｍＮ／ｍ）、ジクロロメタン（同２７．２ｍＮ／ｍ）、１，２−ジクロロエタン（同３１．９ｍＮ／ｍ）、１，１，２，２−テトラクロロエタン（同３５．６ｍＮ／ｍ）等のハロゲン系溶媒や、ジメチルスルホキシド（同４２．９ｍＮ／ｍ）、ホルムアミド（同５７．０ｍＮ／ｍ）等の極性有機溶媒が挙げられる。 The solvent (B) is not particularly limited as long as it has a surface tension at 25 ° C. of 25 mN / m or more and does not dissolve polyolefin. Examples of the solvent (B) include chloroform (surface tension 26.7 mN / m at 25 ° C.), carbon tetrachloride (26.4 mN / m), dichloromethane (27.2 mN / m), 1,2-dichloroethane. (31.9 mN / m), 1,1,2,2-tetrachloroethane (35.6 mN / m), dimethyl sulfoxide (42.9 mN / m), formamide (57. Polar organic solvents such as 0 mN / m).
また、２５℃での表面張力が２５ｍＮ／ｍ未満の溶媒、例えばアセトン（同２３．５ｍＮ／ｍ）、メタノール（同２２．１ｍＮ／ｍ）、エタノール（同２２．０ｍＮ／ｍ）、１−プロパノール（同２３．３ｍＮ／ｍ）、２−プロパノール（同２０．９ｍＮ／ｍ）、酢酸エチル（同２３．４ｍＮ／ｍ）、ジエチルエーテル（同１６．７ｍＮ／ｍ）等についても、例えば水（同７２．８ｍＮ／ｍ）等の２５℃での表面張力が２５ｍＮ／ｍを超える溶媒と混合し、２５℃での表面張力を２５ｍＮ／ｍ以上に調製して溶媒（Ｂ）として使用することもできる。混合溶媒として使用する場合は、乾燥過程で残存する溶媒の表面張力が増大するように、表面張力の高い溶媒の沸点が、表面張力の低い溶媒の沸点よりも高いことが好ましい。 Further, a solvent having a surface tension at 25 ° C. of less than 25 mN / m, such as acetone (23.5 mN / m), methanol (22.1 mN / m), ethanol (22.0 mN / m), 1-propanol (23.3 mN / m), 2-propanol (20.9 mN / m), ethyl acetate (23.4 mN / m), diethyl ether (16.7 mN / m), etc. 72.8 mN / m) and the like, and a solvent having a surface tension at 25 ° C. exceeding 25 mN / m and adjusting the surface tension at 25 ° C. to 25 mN / m or more can also be used as the solvent (B). . When used as a mixed solvent, the boiling point of the solvent having a high surface tension is preferably higher than the boiling point of the solvent having a low surface tension so that the surface tension of the solvent remaining in the drying process increases.
ポリオレフィン微多孔膜（Ａ）に溶媒（Ｂ）を含浸させる方法に特に制限は無く、ポリオレフィン微多孔膜（Ａ）を溶媒（Ｂ）に浸漬させる方法や、溶媒（Ｂ）をポリオレフィン微多孔膜（Ａ）に塗布する方法などが挙げられる。
ポリオレフィン微多孔膜（Ａ）を溶媒（Ｂ）に浸漬させる方法としては、ロール状のポリオレフィン微多孔膜（Ａ）を浸漬させる方法や、枚葉に切り出したポリオレフィン微多孔膜（Ａ）を浸漬させる方法、またロールから繰り出した反物状のポリオレフィン微多孔膜（Ａ）を連続的に溶媒（Ｂ）に槽をくぐらせる方法、などが挙げられる。
溶媒（Ｂ）をポリオレフィン微多孔膜（Ａ）に塗布する方法としては、溶媒（Ｂ）の粘度にもよるが例えば、グラビアコーター法、小径グラビアコーター法、リバースロールコーター法、トランスファロールコーター法、キスコーター法、ディップコーター法、ナイフコーター法、エアドクターブレードコーター法、ブレードコーター法、ロッドコーター法、スクイズコーター法、キャストコーター法、ダイコーター法、スクリーン印刷法、スプレー塗布法などが挙げられる。
The method for impregnating the polyolefin microporous membrane (A) with the solvent (B) is not particularly limited, and the method of immersing the polyolefin microporous membrane (A) in the solvent (B) or the solvent (B) with the polyolefin microporous membrane ( A method of applying to A) may be mentioned.
As a method of immersing the polyolefin microporous membrane (A) in the solvent (B), a method of immersing the roll-shaped polyolefin microporous membrane (A) or a polyolefin microporous membrane (A) cut into a single wafer is immersed. And a method of continuously passing the tank-shaped polyolefin microporous membrane (A) fed from a roll through a solvent (B).
As a method of applying the solvent (B) to the polyolefin microporous membrane (A), although depending on the viscosity of the solvent (B), for example, a gravure coater method, a small diameter gravure coater method, a reverse roll coater method, a transfer roll coater method, Examples thereof include a kiss coater method, a dip coater method, a knife coater method, an air doctor blade coater method, a blade coater method, a rod coater method, a squeeze coater method, a cast coater method, a die coater method, a screen printing method, and a spray coating method.
溶媒（Ｂ）がポリオレフィン微多孔膜（Ａ）に染み込みにくい場合は、ポリオレフィン微多孔膜（Ａ）を真空状態にして細孔内部の空気を除去し、その後溶媒（Ｂ）を注入する真空含浸方法を取っても良い。 When the solvent (B) hardly penetrates into the polyolefin microporous membrane (A), the polyolefin microporous membrane (A) is evacuated to remove air inside the pores, and then inject the solvent (B). You may take it.
溶媒（Ｂ）の除去方法としては、自然乾燥、送風乾燥、加熱乾燥、減圧乾燥などいかなる方法でもよい。なお、溶媒（Ｂ）を含浸したポリオレフィン微多孔膜（Ａ）から除去する際に加熱を行う場合には、ポリオレフィン微多孔膜（Ａ）の細孔が熱によって収縮しない温度で行うことが好ましい。 As a method for removing the solvent (B), any method such as natural drying, air drying, heat drying, and reduced pressure drying may be used. In addition, when performing heating when removing from the polyolefin microporous membrane (A) impregnated with the solvent (B), it is preferable to carry out at a temperature at which the pores of the polyolefin microporous membrane (A) do not shrink by heat.
本願発明において、溶媒（Ｂ）の含浸に際し、予め、溶媒（Ｂ）に可溶な高分子化合物（Ｃ）を溶媒（Ｂ）に溶解し、該溶液を含浸させることができる。かかる高分子化合物（Ｃ）を併用することにより、熱処理温度を超える温度範囲における、改質ポリオレフィン微多孔膜の寸法安定性の一層の向上を図ることができる。本発明の改質ポリオレフィン微多孔膜を電池用セパレータ、特にリチウムイオン電池用セパレータとして用いる場合、高分子化合物（Ｃ）は電池の電解液に不溶であり、またその電池の使用範囲で電気化学的に安定である高分子が好ましい。 In the present invention, upon impregnation with the solvent (B), the polymer compound (C) soluble in the solvent (B) can be dissolved in the solvent (B) in advance and impregnated with the solution. By using this polymer compound (C) in combination, it is possible to further improve the dimensional stability of the modified polyolefin microporous membrane in a temperature range exceeding the heat treatment temperature. When the modified polyolefin microporous membrane of the present invention is used as a battery separator, particularly as a lithium ion battery separator, the polymer compound (C) is insoluble in the battery electrolyte and is electrochemical within the battery usage range. Highly stable polymers are preferred.
高分子化合物（Ｃ）としては、耐熱性の点から、融点が１８０以上の高分子化合物であるのが好ましく、例えば、フッ化ビニリデン−ヘキサフルオロプロピレン−テトラフルオロエチレン共重合体やエチレン−テトラフルオロエチレン共重合体などの含フッ素ゴム、スチレン−ブタジエン共重合体およびその水素化物、メタクリル酸エステル共重合体、アクリロニトリル−アクリル酸エステル共重合体、スチレン−アクリル酸エステル共重合体、エチレンプロピレンラバー、ポリ酢酸ビニルなどのゴム類、ポリビニルアルコール、ポリエチレングリコール、アルギン酸ナトリウム、ポリアクリル酸、ポリアクリルアミド、ポリメタクリル酸等の水溶性ポリマー、セルロースエーテル、ポリフェニレンエーテル、ポリスルホン、ポリエーテルスルホン、ポリフェニレンスルフィド、ポリエーテルイミド、ポリアミドイミド、ポリエーテルアミド、ポリアミド、ポリエステルなどが挙げられ、中でも、セルロースエーテル、ポリエーテルイミド、ポリアミドイミド、ポリエーテルアミド、ポリアミドがより好ましく、セルロースエーテルがさらに好ましい。
セルロースエーテルとしては、例えば、カルボキシメチルセルロース（ＣＭＣ）、ヒドロキシエチルセルロース（ＨＥＣ）、カルボキシエチルセルロース、メチルセルロース、エチルセルロース、シアンエチルセルロース、オキシエチルセルロース等が挙げられ、化学的な安定性に優れたＣＭＣ、ＨＥＣが特に好ましい。
The polymer compound (C) is preferably a polymer compound having a melting point of 180 or more from the viewpoint of heat resistance. For example, vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer or ethylene-tetrafluoro Fluorine-containing rubber such as ethylene copolymer, styrene-butadiene copolymer and its hydride, methacrylic acid ester copolymer, acrylonitrile-acrylic acid ester copolymer, styrene-acrylic acid ester copolymer, ethylene propylene rubber, Rubbers such as polyvinyl acetate, water-soluble polymers such as polyvinyl alcohol, polyethylene glycol, sodium alginate, polyacrylic acid, polyacrylamide, polymethacrylic acid, cellulose ether, polyphenylene ether, polysulfone, polyethers Hong, polyphenylene sulfide, polyether imide, polyamide imide, polyether amide, polyamide, polyester and the like are mentioned. Among them, cellulose ether, polyether imide, polyamide imide, polyether amide, polyamide are more preferable, and cellulose ether is more preferable. .
Examples of the cellulose ether include carboxymethyl cellulose (CMC), hydroxyethyl cellulose (HEC), carboxyethyl cellulose, methyl cellulose, ethyl cellulose, cyanethyl cellulose, oxyethyl cellulose and the like, and CMC and HEC excellent in chemical stability are particularly preferable. .
本発明の製造方法により得られる改質ポリオレフィン微多孔膜は、原料として使用されるポリオレフィン微多孔膜に比して、該ポリオレフィン微多孔膜に施された熱処理での熱処理温度を超える温度範囲における寸法安定性が向上している。 The modified polyolefin microporous membrane obtained by the production method of the present invention has dimensions in a temperature range that exceeds the heat treatment temperature in the heat treatment applied to the polyolefin microporous membrane as compared to the polyolefin microporous membrane used as a raw material. Stability is improved.
寸法安定性は、改質ポリオレフィン微多孔膜の加熱形状維持率を算出することにより評価することができる。加熱形状維持率は、実施例に記載の方法と同様の方法で算出することができる。加熱形状維持率が高いほど、改質ポリオレフィン微多孔膜は寸法安定性が向上していることを意味する。 The dimensional stability can be evaluated by calculating the heating shape retention rate of the modified polyolefin microporous membrane. The heating shape maintenance rate can be calculated by the same method as that described in the examples. A higher heating shape retention rate means that the modified polyolefin microporous membrane has improved dimensional stability.
本発明の製造方法により得られる改質ポリオレフィン微多孔膜は、高温時の寸法安定性に優れるので、様々な用途に用いることができ、中でも電池用セパレータとして、特には非水電解液二次電池セパレータとして好適に用いることができる。 The modified polyolefin microporous membrane obtained by the production method of the present invention is excellent in dimensional stability at high temperatures, and can be used for various applications. In particular, as a battery separator, particularly a non-aqueous electrolyte secondary battery. It can be suitably used as a separator.
以下に実施例を挙げて本発明をより具体的に説明するが、本発明はこれらに限定されるものではない。 Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples.
実施例及び比較例のポリオレフィン微多孔膜および改質ポリオレフィン微多孔膜の物性等は以下の方法で測定した。
（１）厚み測定（単位：μｍ）
ポリオレフィン微多孔膜および改質ポリオレフィン微多孔膜厚みは、ＪＩＳ規格（Ｋ７１３０−１９９２）に従い、測定した。
（３）空隙率（単位：体積％）
ポリオレフィン微多孔膜から、一辺の長さ１０ｃｍの正方形のサンプルを切り出し、重量Ｗ（ｇ）と厚みＤ（ｃｍ）を測定した。サンプル中のそれぞれの材質の重量（Ｗｉ（ｇ））を求め、それぞれの材質について、Ｗｉ（ｇ）と真比重（真比重ｉ（ｇ／ｃｍ３））とから体積を算出して、次式より空隙率（体積％）を求めた。
空隙率（体積％）＝１００−［｛（Ｗ１／真比重１）＋（Ｗ２／真比重２）＋・・＋（Ｗｎ／真比重ｎ）｝／（１０×１０×Ｄ）］×１００
The physical properties of the polyolefin microporous membranes and modified polyolefin microporous membranes of Examples and Comparative Examples were measured by the following methods.
(1) Thickness measurement (unit: μm)
The thickness of the polyolefin microporous membrane and the modified polyolefin microporous membrane were measured in accordance with JIS standards (K7130-1992).
(3) Porosity (unit: volume%)
A square sample having a side length of 10 cm was cut out from the polyolefin microporous membrane, and the weight W (g) and the thickness D (cm) were measured. The weight (Wi (g)) of each material in the sample is obtained, and the volume of each material is calculated from Wi (g) and true specific gravity (true specific gravity i (g / cm 3 )). Further, the porosity (volume%) was obtained.
Porosity (volume%) = 100 − [{(W1 / true specific gravity 1) + (W2 / true specific gravity 2) + ·· + (Wn / true specific gravity n)} / (10 × 10 × D)] × 100
（４）透気度（単位：秒／１００ｃｃ）
ポリオレフィン微多孔膜および改質ポリオレフィン微多孔膜の透気度は、ＪＩＳ Ｐ８１１７に基づいて、（株）東洋精機製作所製のデジタルタイマー式ガーレ式デンソメータで測定した。
（５）フィルム平均孔径
ＪＩＳ Ｋ ３８３２の規定に基づいて、Ａｕｔｏｍａｔｅｄ Ｃａｐｉｌｌａｒｙ Ｆｌｏｗ Ｐｏｒｏｍｅｔｅｒ（ＰＯＲＯＵＳ ＭＡＴＥＲＩＡＬＳ ＩＮＣ社製）を用い、含浸液をフロリナートＦＣ−４０（住友スリーエム（株）製）として、ポリオレフィン微多孔膜の平均孔径を求めた。
(4) Air permeability (unit: seconds / 100cc)
The air permeability of the polyolefin microporous membrane and the modified polyolefin microporous membrane was measured with a digital timer type Gurley type densometer manufactured by Toyo Seiki Seisakusho, based on JIS P8117.
(5) Average film pore diameter Based on the provisions of JIS K 3832, using an Automated Capillary Flow Porometer (manufactured by POROUS MATERIALS INC.), The impregnating solution was Fluorinert FC-40 (manufactured by Sumitomo 3M Co., Ltd.), and a polyolefin microporous membrane The average pore diameter was determined.
（６）加熱形状維持率
ポリオレフィン微多孔膜および改質ポリオレフィン微多孔膜を８ｃｍ×８ｃｍに切り出し、中央に、各辺がＭＤ方向（ポリオレフィン微多孔膜を作製したときの流れ方向）とＴＤ方向（ポリオレフィン微多孔膜を作製したときの流れ方向と直交する方向）のいずれか一方向と平行となるように６ｃｍ×６ｃｍの正方形を記入した後、2枚の紙で挟み込んだ状態で１３０℃のオーブンに１時間静置して加熱した。所定時間加熱後にオーブンから取り出したサンプルについて、面内に記入した正方形の各辺の寸法を測定し、ＭＤ方向に平行な一辺とＴＤ方向に平行な一辺について、次式より加熱形状維持率を算出した。
加熱形状維持率（％）＝ 加熱後の寸法÷加熱前の寸法×１００
(6) Heating shape maintenance rate A polyolefin microporous membrane and a modified polyolefin microporous membrane are cut into 8 cm × 8 cm, and each side has MD direction (flow direction when producing a polyolefin microporous membrane) and TD direction ( Enter a 6cm x 6cm square so that it is parallel to any one of the directions (perpendicular to the flow direction when the polyolefin microporous membrane was made), and then sandwich it between two sheets of paper at 130 ° C. And left to heat for 1 hour. For the sample taken out of the oven after heating for a predetermined time, measure the dimension of each side of the square written in the plane, and calculate the heating shape maintenance rate from the following formula for one side parallel to the MD direction and one side parallel to the TD direction. did.
Heated shape retention rate (%) = dimension after heating ÷ dimension before heating x 100
（ポリオレフィン微多孔膜の作製）
超高分子量ポリエチレン粉末（三井化学（株）製の「３４０Ｍ」）７０重量％および重量平均分子量１０００のポリエチレンワックス（日本精鑞（株）製の「ＦＮＰ−０１１５」）３０重量％と、該超高分子量ポリエチレンとポリエチレンワックスとの合計量１００重量部に対して、酸化防止剤（チバ・スペシャリティ・ケミカルズ（株）製の「Ｉｒｇ１０１０」）を０．４重量％、Ｐ１６８（チバ・スペシャリティ・ケミカルズ（株）製）を０．１重量％、ステアリン酸ナトリウムを１．３重量％を加え、更に全体積に対して３８体積％となるように平均孔径０．１μｍの炭酸カルシウム（丸尾カルシウム（株）製）を加え、これらを粉末のままヘンシェルミキサーで混合した後、二軸混練機で溶融混練してポリオレフィン樹脂組成物とした。該ポリオレフィン樹脂組成物を表面温度が１５０℃の一対のロールにて圧延しシートを作成した。このシートを塩酸水溶液（塩酸４ｍｏｌ／Ｌ、非イオン系界面活性剤０．５重量％）に浸漬させることで炭酸カルシウムを除去し、続いてＴＤ方向に延伸した後に１２０℃で熱処理して、表１に示す性状のポリオレフィン微多孔膜Ａ１〜Ａ３を得た。
(Production of polyolefin microporous membrane)
70% by weight of ultra high molecular weight polyethylene powder (“340M” manufactured by Mitsui Chemicals, Inc.) and 30% by weight of polyethylene wax having a weight average molecular weight of 1000 (“FNP-0115” manufactured by Nippon Seiki Co., Ltd.) 0.4 wt% of antioxidant (“Irg1010” manufactured by Ciba Specialty Chemicals Co., Ltd.) and P168 (Ciba Specialty Chemicals (Ciba Specialty Chemicals)) with respect to 100 parts by weight of the total amount of high molecular weight polyethylene and polyethylene wax Co., Ltd.) 0.1% by weight, sodium stearate 1.3% by weight, and calcium carbonate having an average pore size of 0.1 μm (Maruo Calcium Co. Are mixed with a Henschel mixer in the form of a powder, and then melt-kneaded with a biaxial kneader to obtain a polyolefin resin composition. . The polyolefin resin composition was rolled with a pair of rolls having a surface temperature of 150 ° C. to prepare a sheet. The sheet was immersed in an aqueous hydrochloric acid solution (hydrochloric acid 4 mol / L, nonionic surfactant 0.5% by weight) to remove calcium carbonate, and subsequently stretched in the TD direction and then heat treated at 120 ° C. Polyolefin microporous membranes A1 to A3 having the properties shown in FIG.
（実施例１）
ポリオレフィン微多孔膜Ａ１にエタノール３０ｗｔ％水溶液（２５℃における溶媒表面張力が５７．５ｄｙｎ／ｃｍ）をバーコーターで塗工し、室温で乾燥させて改質ポリオレフィン微多孔膜を得た。改質ポリオレフィン微多孔膜の膜厚は１６．３μｍ、透気度は１１２秒／１００ｃｃであった。また、改質ポリオレフィン微多孔膜の加熱形状維持率を表２に示す。
Example 1
A 30 wt% ethanol aqueous solution (solvent surface tension at 25 ° C. of 57.5 dyn / cm) was applied to the polyolefin microporous membrane A1 with a bar coater and dried at room temperature to obtain a modified polyolefin microporous membrane. The film thickness of the modified polyolefin microporous film was 16.3 μm, and the air permeability was 112 seconds / 100 cc. Table 2 shows the heating shape retention rate of the modified polyolefin microporous membrane.
（実施例２）
ポリオレフィン微多孔膜Ａ１にエタノール３０ｗｔ％水溶液にカルボキシメチルセルロース（第一工業製薬（株）製の「ＷＳ−Ｃ」）（以下ＣＭＣと略す場合あり）を１ｗｔ％溶解させた溶液を、バーコーターで塗工し室温で乾燥させて改質ポリオレフィン微多孔膜を得た。改質ポリオレフィン微多孔膜の膜厚は１６．３μｍ、透気度は１１７秒／１００ｃｃであった。また、改質ポリオレフィン微多孔膜の加熱形状維持率を表２に示す。
(Example 2)
A solution obtained by dissolving 1 wt% of carboxymethyl cellulose (“WS-C” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) (hereinafter sometimes abbreviated as CMC) in a 30 wt% ethanol aqueous solution in a polyolefin microporous membrane A1 is applied with a bar coater. And dried at room temperature to obtain a modified polyolefin microporous membrane. The film thickness of the modified polyolefin microporous film was 16.3 μm, and the air permeability was 117 seconds / 100 cc. Table 2 shows the heating shape retention rate of the modified polyolefin microporous membrane.
（実施例３）
ポリオレフィン微多孔膜Ａ２にエタノール３０ｗｔ％水溶液をバーコーターで塗工し、室温で乾燥させて改質ポリオレフィン微多孔膜を得た。ポリオレフィン微多孔膜Ａ２の膜厚は１６．０μｍ、透気度は１３３秒／１００ｃｃであった。また改質ポリオレフィン微多孔膜の加熱形状維持率を表２に示す。
(Example 3)
A 30 wt% ethanol aqueous solution was applied to the polyolefin microporous membrane A2 with a bar coater and dried at room temperature to obtain a modified polyolefin microporous membrane. The polyolefin microporous membrane A2 had a thickness of 16.0 μm and an air permeability of 133 seconds / 100 cc. Table 2 shows the heating shape retention rate of the modified polyolefin microporous membrane.
（実施例４）
ポリオレフィン微多孔膜Ａ２にエタノール３０ｗｔ％水溶液にカルボキシメチルセルロース（第一工業製薬（株）製の「ＷＳ−Ｃ」）を１ｗｔ％溶解させた溶液を、バーコーターで塗工し室温で乾燥させて改質ポリオレフィン微多孔膜を得た。改質ポリオレフィン微多孔膜の膜厚は１５．５μｍ、透気度は１９０秒／１００ｃｃであった。また、改質ポリオレフィン微多孔膜の加熱形状維持率を表２に示す。
Example 4
A solution obtained by dissolving 1 wt% of carboxymethyl cellulose (“WS-C” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in a 30 wt% ethanol solution in a polyolefin microporous membrane A2 was coated with a bar coater and dried at room temperature. A porous polyolefin microporous membrane was obtained. The modified polyolefin microporous membrane had a thickness of 15.5 μm and an air permeability of 190 seconds / 100 cc. Table 2 shows the heating shape retention rate of the modified polyolefin microporous membrane.
（実施例５）
ポリオレフィン微多孔膜Ａ３にエタノール３０ｗｔ％水溶液にカルボキシメチルセルロース（第一工業製薬製、ＷＳ−Ｃ）を０．３ｗｔ％溶解させた溶液を、バーコーターで塗工し室温で乾燥させて改質ポリオレフィン微多孔膜を得た。改質ポリオレフィン微多孔膜の膜厚は１５．７μｍ、透気度は１５９秒／１００ｃｃであった。また、改質ポリオレフィン微多孔膜の加熱形状維持率を表２に示す。
(Example 5)
A solution of 0.3 wt% carboxymethyl cellulose (Daiichi Kogyo Seiyaku Co., Ltd., WS-C) dissolved in 30 wt% ethanol solution in polyolefin microporous membrane A3 was coated with a bar coater and dried at room temperature to modify the modified polyolefin fine particles. A porous membrane was obtained. The film thickness of the modified polyolefin microporous film was 15.7 μm, and the air permeability was 159 seconds / 100 cc. Table 2 shows the heating shape retention rate of the modified polyolefin microporous membrane.
（実施例６）
ポリオレフィン微多孔膜Ａ３にエタノール３０ｗｔ％水溶液にカルボキシメチルセルロース（第一工業製薬（株）製の「ＷＳ−Ｃ」）を１ｗｔ％溶解させた溶液を、バーコーターで塗工し室温で乾燥させて改質ポリオレフィン微多孔膜を得た。改質ポリオレフィン微多孔膜の膜厚は１５．３μｍ、透気度は２１８秒／１００ｃｃであった。また、改質ポリオレフィン微多孔膜の加熱形状維持率を表２に示す。
(Example 6)
A solution prepared by dissolving 1 wt% of carboxymethyl cellulose (“WS-C” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) in a 30 wt% ethanol solution in a polyolefin microporous membrane A3 was coated with a bar coater and dried at room temperature. A porous polyolefin microporous membrane was obtained. The film thickness of the modified polyolefin microporous membrane was 15.3 μm, and the air permeability was 218 seconds / 100 cc. Table 2 shows the heating shape retention rate of the modified polyolefin microporous membrane.
（実施例７）
ポリオレフィン微多孔膜Ａ３にクロロホルム（２５℃における溶媒表面張力が２６．７ｄｙｎ／ｃｍ）をバーコーターで塗工し、室温で乾燥させて改質ポリオレフィン微多孔膜を得た。改質ポリオレフィン微多孔膜の膜厚は１７．２μｍ、透気度は１３０秒／１００ｃｃであった。また、改質ポリオレフィン微多孔膜の加熱形状維持率を表２に示す。
(Example 7)
Chloroform (solvent surface tension at 25 ° C .: 26.7 dyn / cm) was applied to the polyolefin microporous membrane A3 with a bar coater and dried at room temperature to obtain a modified polyolefin microporous membrane. The film thickness of the modified polyolefin microporous membrane was 17.2 μm, and the air permeability was 130 seconds / 100 cc. Table 2 shows the heating shape retention rate of the modified polyolefin microporous membrane.
（比較例１）
ポリオレフィン微多孔膜Ａ３にエタノール（２５℃における溶媒表面張力が２２．０ｄｙｎ／ｃｍ）をバーコーターで塗工し、室温で乾燥させた。乾燥後のポリオレフィン微多孔膜Ａ３の膜厚は１７．３μｍ、透気度は１２７秒／１００ｃｃであった。乾燥後のポリオレフィン微多孔膜の加熱形状維持率を表２に示す。
(Comparative Example 1)
Ethanol (the solvent surface tension at 25 ° C. was 22.0 dyn / cm) was applied to the polyolefin microporous membrane A3 with a bar coater and dried at room temperature. The film thickness of the microporous polyolefin membrane A3 after drying was 17.3 μm, and the air permeability was 127 seconds / 100 cc. Table 2 shows the heating shape retention rate of the polyolefin microporous membrane after drying.
Claims (4)
溶媒（Ｂ）：２５℃における表面張力が２５ｍＮ／ｍ以上であって、かつポリオレフィンを溶解しない溶媒。 A modified polyolefin fine film characterized by impregnating a microporous membrane (A) made of polyolefin with a solution consisting of the following solvent (B) and polymer compound (C) and then removing the solvent (B). A method for producing a porous membrane.
Solvent (B): A solvent having a surface tension at 25 ° C. of 25 mN / m or more and does not dissolve polyolefin.
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