JPH11297296A - Porous film, surface treatment agent and surface treatment method - Google Patents
Porous film, surface treatment agent and surface treatment methodInfo
- Publication number
- JPH11297296A JPH11297296A JP10095943A JP9594398A JPH11297296A JP H11297296 A JPH11297296 A JP H11297296A JP 10095943 A JP10095943 A JP 10095943A JP 9594398 A JP9594398 A JP 9594398A JP H11297296 A JPH11297296 A JP H11297296A
- Authority
- JP
- Japan
- Prior art keywords
- molecular weight
- weight component
- porous membrane
- surface treatment
- polyolefin resin
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Classifications
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/10—Energy storage using batteries
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、電池用セパレー
タ、コンデンサ用セパレータ、溶剤分離膜等のように非
水系溶剤と接触させて使用される多孔質膜、その製造の
ための表面処理剤、並びに該表面処理剤を用いる表面処
理方法に関する。The present invention relates to a porous membrane used in contact with a non-aqueous solvent such as a battery separator, a capacitor separator, a solvent separation membrane and the like, a surface treating agent for producing the same, and The present invention relates to a surface treatment method using the surface treatment agent.
【０００２】[0002]
【従来の技術】近年、電子機器のコードレス化、ポータ
ブル化にともない、これらの駆動用電源として高エネル
ギー密度、高起電力、自己放電の少ないリチウム電池が
注目を集めている。さらに、環境問題、エネルギー問題
が年々活発に討議されるようになっており、今後ますま
す高性能、高容量、高出力電池が要望されるのは必至で
ある。すでにHV（ハイブリッドカー）、ZEV （ゼロ排気
ガス車）などに代表されるような電気自動車用電池、ま
たは大型蓄電池などでもリチウム電池が有力視されてい
る。2. Description of the Related Art In recent years, as electronic devices have become cordless and portable, lithium batteries having high energy density, high electromotive force, and low self-discharge have attracted attention as driving power sources for these devices. Furthermore, environmental issues and energy issues are being actively discussed year by year, and it is inevitable that higher performance, higher capacity, and higher output batteries will be required in the future. Lithium batteries are already promising for batteries for electric vehicles, such as HVs (hybrid cars) and ZEVs (zero-emission vehicles), and large storage batteries.
【０００３】しかしながら、これら電池の大型化によ
り、一層の安全性に対する要求が高まるのも事実であ
り、特に耐熱性についての要求が高まっている。高耐熱
性に関しては、ポリイミド、ポリフェニレンサルファイ
ド（ＰＰＳ）、ポリエーテルエーテルケトン（ＰＥＥ
Ｋ）などの材料も挙げられるが、有機溶媒中の安定性、
多孔質化技術の適性を考慮するとフッ素樹脂を用いるの
が有利と考えられる。However, it is a fact that the demand for further safety is increased due to the increase in the size of these batteries, and the demand for heat resistance is particularly increased. Regarding high heat resistance, polyimide, polyphenylene sulfide (PPS), polyetheretherketone (PEE)
K) and the like, but also stability in an organic solvent,
Considering the suitability of the porous technology, it is considered advantageous to use a fluororesin.
【０００４】しかし、リチウム電池の電解液としては、
エチレンカーボネート、プロピレンカーボネートなどが
用いられ、それらは極性が高く、また液体の表面張力も
30ダイン／cm程度であり、フッ素樹脂に比べて大きい。
ゆえにフッ素樹脂をそのまま電解液に接触させても濡れ
ず、結果電気抵抗は高く、電池特性を満足するセパレー
タとしては使用できない。However, as an electrolyte for a lithium battery,
Ethylene carbonate, propylene carbonate, etc. are used.
It is about 30 dynes / cm, which is larger than fluororesin.
Therefore, even if the fluororesin is brought into contact with the electrolytic solution as it is, it does not get wet, resulting in high electric resistance and cannot be used as a separator satisfying battery characteristics.
【０００５】このため、親水処理を施したフッ素樹脂多
孔質膜をセパレータとして用いる技術が報告されている
が（特開平5 −205721号公報）、リチウム電池は特に水
が厳禁であり、セパレータが吸水性であることは電池の
安全性にも影響するので、取り扱い上十分に留意する必
要が生ずる。また、含フッ素モノマーと親水基含有モノ
マーによるコポリマーの付着による親水性フッ素樹脂多
孔質材料についても報告されているが（特開平7 −1927
16号公報）、同様に、吸水性の懸念から、リチウム電池
用セパレータとしては使用に関して十分な注意を払う必
要がある。更に、フッ素樹脂多孔質膜を界面活性剤によ
り処理することで、フッ素樹脂多孔質膜表面の臨界表面
張力を制御できるが、この方法では、経時で界面活性剤
の効力がなくなり、実質的に電解液に対するぬれ性の維
持が困難である。For this reason, a technique using a fluororesin porous membrane which has been subjected to a hydrophilic treatment as a separator has been reported (Japanese Patent Laid-Open No. 5-205721). Since the nature of the battery also affects the safety of the battery, it is necessary to pay sufficient attention to handling. A hydrophilic fluororesin porous material obtained by adhesion of a copolymer of a fluorine-containing monomer and a hydrophilic group-containing monomer has also been reported (JP-A-7-1927).
Similarly, due to concerns about water absorption, it is necessary to pay sufficient attention to use as a separator for a lithium battery. Further, by treating the fluororesin porous membrane with a surfactant, the critical surface tension of the fluororesin porous membrane surface can be controlled. However, in this method, the surfactant becomes ineffective over time, and the electrolytic solution is substantially eliminated. It is difficult to maintain wettability with the liquid.
【０００６】一方、フッ素樹脂多孔質膜の小繊維表面に
低分子量ポリエチレンを固定することにより、電解液の
濡れ性を向上させた電池用セパレータ（特開平1 −1493
60号公報）も報告されている。On the other hand, a battery separator having improved wettability of an electrolyte by fixing low molecular weight polyethylene on the surface of small fibers of a fluororesin porous membrane (Japanese Patent Laid-Open No. 1-1493).
No. 60 gazette).
【０００７】[0007]
【発明が解決しようとする課題】しかしながら、低分子
量ポリエチレンはそれ自体電解液に対して、わずかであ
るが溶解性があり、電池内の反応等によりフッ素樹脂膜
から脱落し、徐々に電解液に対するぬれ性の低下、膜抵
抗値の上昇等の経時による変化が生じるという問題があ
った。However, the low molecular weight polyethylene itself is slightly soluble in the electrolytic solution itself, falls off from the fluororesin film due to a reaction in the battery, etc., and gradually comes into contact with the electrolytic solution. There has been a problem that changes over time, such as a decrease in wettability and an increase in film resistance, occur.
【０００８】そして、このように濡れ性改善剤である低
分子量ポリエチレンが基材から脱落するという問題は、
電池用セパレータに限られたものではなく、コンデンサ
用セパレータ、溶剤分離膜等のように非水系溶剤、特に
非水系電解液と接触させて使用される多孔質膜にも共通
する課題である。[0008] The problem that the low-molecular-weight polyethylene, which is a wetting agent, falls off from the substrate,
The present invention is not limited to battery separators, but is also a problem common to porous membranes used in contact with non-aqueous solvents, particularly non-aqueous electrolytes, such as capacitor separators and solvent separation membranes.
【０００９】従って、本発明の目的は、上記問題点を解
消すべく、濡れ性改善剤である低分子量ポリオレフィン
の濡れ性等の機能を損なうことなく、その脱落の防止を
可能とした多孔質膜、その製造のための表面処理剤、並
びに該表面処理剤を用いる表面処理方法を提供すること
にある。SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-mentioned problems by providing a porous membrane capable of preventing a low-molecular-weight polyolefin as a wettability improver from falling off without impairing its function such as wettability. It is another object of the present invention to provide a surface treatment agent for producing the same, and a surface treatment method using the surface treatment agent.
【００１０】[0010]
【課題を解決するための手段】本発明者らは、上記の目
的を達成すべく、各種表面処理剤について鋭意研究した
ところ、より分子量の大きい高分子量成分を添加した表
面処理剤を用いることにより、意外にも簡易な方法で上
記目的が達成できることを見出した。Means for Solving the Problems The present inventors have conducted intensive studies on various surface treatment agents to achieve the above object, and have found that by using a surface treatment agent to which a high molecular weight component having a higher molecular weight is added. It has been surprisingly found that the above object can be achieved by a simple method.
【００１１】即ち、本発明の多孔質膜は、基材となる高
分子多孔質膜の微細組織表面に、ポリオレフィン樹脂が
付着してなる多孔質膜において、前記ポリオレフィン樹
脂は、濡れ性改善剤である低分子量成分に対して、より
分子量の大きい高分子量成分が、均質に混合されている
ことを特徴とするものである。That is, the porous membrane of the present invention is a porous membrane in which a polyolefin resin is adhered to the surface of a microstructure of a polymer porous membrane serving as a base material. A high molecular weight component having a higher molecular weight is homogeneously mixed with a certain low molecular weight component.
【００１２】上記において、ポリオレフィン樹脂の種類
や分子量は、後述のとおりであるが、特に、前記低分子
量成分が、粘度平均分子量10000 以下のポリエチレンで
あり、前記高分子量成分が粘度平均分子量20000 〜3500
00のポリエチレンであることが、後述の作用効果より好
ましい。In the above, the type and molecular weight of the polyolefin resin are as described below. In particular, the low molecular weight component is polyethylene having a viscosity average molecular weight of 10,000 or less, and the high molecular weight component is a viscosity average molecular weight of 20,000 to 3,500.
The polyethylene of 00 is more preferable than the operation and effect described below.
【００１３】また、前記高分子量成分の含有量が、前記
ポリオレフィン樹脂中の５〜６０重量％であることが、
後述の作用効果より好ましい。Further, the content of the high molecular weight component is 5 to 60% by weight in the polyolefin resin.
It is more preferable than the operation and effect described below.
【００１４】基材となる高分子多孔質膜は、フッ素樹脂
多孔質膜、殊にポリテトラフルオロエチレン多孔質膜で
あることが、好適である。The polymer porous membrane serving as the base material is preferably a fluororesin porous membrane, particularly a polytetrafluoroethylene porous membrane.
【００１５】また、本発明の多孔質膜は、非水電解液用
セパレータとして好適に用いられる。Further, the porous membrane of the present invention is suitably used as a separator for a non-aqueous electrolyte.
【００１６】一方、本発明の表面処理剤は、ポリオレフ
ィン樹脂とその溶媒とを含有し、高分子多孔質膜の濡れ
性を改善するための表面処理剤において、前記ポリオレ
フィン樹脂は、濡れ性改善剤である低分子量成分と、よ
り分子量の大きい高分子量成分とを含有してなることを
特徴とする。On the other hand, the surface treatment agent of the present invention contains a polyolefin resin and a solvent thereof, and is a surface treatment agent for improving the wettability of a polymer porous membrane. And a high molecular weight component having a higher molecular weight.
【００１７】他方、本発明の表面処理方法は、上記の表
面処理剤を高分子多孔質膜に接触・保持させた状態で、
前記溶媒を除去して、前記ポリオレフィン樹脂を前記高
分子多孔質膜の微細組織表面に付着させるものである。On the other hand, according to the surface treatment method of the present invention, the above-mentioned surface treatment agent is brought into contact with and held by the porous polymer membrane,
The solvent is removed to allow the polyolefin resin to adhere to the surface of the microstructure of the polymer porous membrane.
【００１８】〔作用効果〕そして、本発明の多孔質膜に
よると、後述の実施例の結果が示すように、低分子量成
分に対して、より分子量の大きい高分子量成分を均質に
混合しているため、濡れ性改善剤である低分子量ポリオ
レフィンの濡れ性等の機能を損なうことなく、その脱落
の防止することができる。そして、その機構は、次のよ
うに推定される。[Effects] According to the porous membrane of the present invention, a high molecular weight component having a larger molecular weight is homogeneously mixed with a low molecular weight component, as shown in the results of Examples described later. Therefore, it is possible to prevent the low-molecular-weight polyolefin, which is a wettability improver, from falling off without impairing the functions such as wettability. Then, the mechanism is presumed as follows.
【００１９】つまり、低分子量成分は、その単独使用で
は化学的、物理的な安定性が比較的低いのに対し、より
分子量の大きい高分子量成分を均質に混合したものは、
分子レベルで相互作用して化学的、物理的な安定性が高
まり、溶媒や反応種の影響を受けにくくなり、しかも、
このような混合状態は低分子量成分の基材への付着性や
溶媒等の濡れ性や電気的性質など、低分子量成分に期待
される各種機能の妨げとならないと考えられる。そし
て、このような機構は、ポリエチレンに限られず各種ポ
リオレフィンについても応用できると考えられる。That is, the low molecular weight component has relatively low chemical and physical stability when used alone, whereas the low molecular weight component obtained by homogeneously mixing a high molecular weight component having a higher molecular weight is
Interactions at the molecular level increase chemical and physical stability, are less susceptible to solvents and reactive species, and
It is considered that such a mixed state does not hinder various functions expected of the low molecular weight component, such as adhesion of the low molecular weight component to the substrate, wettability of a solvent or the like, and electrical properties. And it is thought that such a mechanism can be applied not only to polyethylene but also to various polyolefins.
【００２０】前記低分子量成分が、粘度平均分子量1000
0 以下のポリエチレンであり、前記高分子量成分が粘度
平均分子量20000 〜350000のポリエチレンである場合、
後述の実施例の結果が示すように、特に膜抵抗の経時変
化が小さくなるという効果が得られる。つまり、粘度平
均分子量10000 以下のポリエチレンは、濡れ性の改善効
果が高く、これに粘度平均分子量20000 〜350000のポリ
エチレンを均質に混合することにより、上記の脱落防止
などの作用効果がより顕著になる。また、前記高分子量
成分の含有量が、前記ポリオレフィン樹脂中の５〜６０
重量％である場合、表面処理の作業性、電解液に対する
ぬれ性、低分子量成分の脱落阻止効果等が特に良好にな
る。逆に、この範囲を超えると、作業性の低下、電解液
に対するぬれ性の低下などが生じる傾向があり、また、
この範囲未満だと、低分子量ポリエチレンの脱落を阻止
しにくく、経時変化による影響が生じる傾向がある。か
かる観点から、より好ましくは、２０〜４０重量％であ
る。The low molecular weight component has a viscosity average molecular weight of 1000
0 or less polyethylene, wherein the high molecular weight component is a polyethylene having a viscosity average molecular weight of 20,000 to 350,000,
As shown in the results of the examples described later, an effect is obtained that the change with time of the film resistance is particularly reduced. In other words, polyethylene having a viscosity average molecular weight of 10,000 or less has a high effect of improving wettability, and by uniformly mixing polyethylene having a viscosity average molecular weight of 20,000 to 350,000, the above-described effects such as prevention of falling off become more remarkable. . Further, the content of the high molecular weight component is 5 to 60 in the polyolefin resin.
In the case of the weight percentage, the workability of the surface treatment, the wettability to the electrolytic solution, the effect of preventing the low molecular weight component from falling off, and the like are particularly good. Conversely, if it exceeds this range, the workability tends to decrease, and the wettability to the electrolyte tends to decrease.
If it is less than this range, it is difficult to prevent the low-molecular-weight polyethylene from falling off, and there is a tendency that the influence of a change with time is caused. From this viewpoint, the content is more preferably 20 to 40% by weight.
【００２１】基材となる高分子多孔質膜が、フッ素樹
脂、例えばポリテトラフルオロエチレン多孔質膜である
場合、基材としての耐熱性、製膜性、耐溶剤性が良好な
点に加えて、ポリオレフィン樹脂による表面処理の効果
が高く、特に本発明による脱落阻止効果が有効となる。When the polymer porous membrane serving as the base material is a fluororesin, for example, a polytetrafluoroethylene porous membrane, the base material has good heat resistance, film forming property, and solvent resistance in addition to the good properties. The effect of the surface treatment with the polyolefin resin is high, and the effect of preventing falling off according to the present invention is particularly effective.
【００２２】また、本発明の多孔質膜が、非水電解液用
セパレータとして用いられる場合、、非水電解液を用い
る電池、特にリチウム電池において用いられる電解液に
対する低分子量成分の溶解性や、電池内の反応等による
脱落などを特に有効に改善し、電解液に対するぬれ性の
低下や膜抵抗値の上昇等の経時による変化を有効に防止
することができる。しかも、電解液との親和性も十分で
あると共に、セパレー夕内への水の浸入などの問題も生
じにくい。When the porous membrane of the present invention is used as a separator for a non-aqueous electrolyte, the solubility of a low molecular weight component in a battery using a non-aqueous electrolyte, particularly an electrolyte used in a lithium battery, Particularly, dropout due to a reaction or the like in the battery can be particularly effectively improved, and a change with time, such as a decrease in wettability to an electrolytic solution or an increase in a film resistance value, can be effectively prevented. In addition, the affinity with the electrolyte is sufficient, and problems such as intrusion of water into the separator are unlikely to occur.
【００２３】一方、本発明の表面処理剤によると、ポリ
オレフィン樹脂が、濡れ性改善剤である低分子量成分
と、より分子量の大きい高分子量成分とを含有している
ため、上記のような作用効果を得ることができる多孔質
膜を好適に製造することができる。On the other hand, according to the surface treatment agent of the present invention, since the polyolefin resin contains a low molecular weight component which is a wettability improving agent and a high molecular weight component having a larger molecular weight, the above-mentioned effects are obtained. Can be suitably produced.
【００２４】他方、本発明の表面処理方法によると、上
記の表面処理剤をフッ素樹脂多孔質膜に接触・保持させ
た状態で、前記溶媒を除去して、前記ポリオレフィン樹
脂を前記フッ素樹脂多孔質膜の微細組織表面に付着させ
るという、簡易な方法で、上記のような作用効果を得る
ことができる多孔質膜を好適に製造することができる。On the other hand, according to the surface treatment method of the present invention, the solvent is removed while the surface treating agent is in contact with and held by the fluororesin porous membrane, and the polyolefin resin is removed from the fluororesin porous membrane. By a simple method of attaching the film to the surface of the microstructure of the film, it is possible to suitably manufacture a porous film capable of obtaining the above-described effects.
【００２５】[0025]
【発明の実施の形態】以下、本発明の多孔質膜、表面処
理剤および表面処理方法について順に説明する。BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a porous membrane, a surface treating agent and a surface treating method of the present invention will be described in order.
【００２６】（本発明の多孔質膜）基材となる高分子多
孔質膜としては、その材料として、ポリテトラフルオロ
エチレン（ＰＴＦＥ）、テトラフルオロパーアルコキシ
ビニルエーテル共重合体（ＰＦＡ）、ポリフッ化ビニ
ル、ポリフッ化ビニリデン、ポリ三フッ化塩化エチレン
及びこれらの共重合体、六フッ化エチレンプロピレン共
重合体などのフッ素樹脂、殊にＰＴＦＥが最も適してい
る。なお、未処理のＰＴＦＥ多孔質膜は電解液によって
ぬれず、これは、ＰＴＦＥの表面張力が小さいのが原因
と考えられる。(Porous Membrane of the Present Invention) As the polymer porous membrane serving as the base material, polytetrafluoroethylene (PTFE), tetrafluoroperalkoxyvinyl ether copolymer (PFA), polyvinyl fluoride Fluororesins such as polyvinylidene fluoride, polyvinylidene trichloride, copolymers thereof, and hexafluoroethylene propylene copolymer, especially PTFE are most suitable. The untreated porous PTFE membrane was not wetted by the electrolytic solution, which is considered to be due to the low surface tension of PTFE.
【００２７】フッ素樹脂多孔質膜の平均孔径は、分離す
る対象に応じて０．０５〜１０μｍの範囲で適宜決定さ
れるが、電池用セパレータの場合には、０．２〜５μｍ
程度が好ましい。また、空孔率は、本発明を適用する上
で、４０〜９５％が好ましい。The average pore diameter of the fluororesin porous membrane is appropriately determined within the range of 0.05 to 10 μm according to the object to be separated. In the case of a battery separator, the average pore diameter is 0.2 to 5 μm.
The degree is preferred. The porosity is preferably 40 to 95% in applying the present invention.
【００２８】基材の微細組織表面に付着するポリオレフ
ィン樹脂は、親水基を持たない疎水性樹脂であり、吸水
性に関する前述の問題が生じにくい。ポリオレフィン樹
脂としては、臨界表面張力20〜40ダイン／cmのものがい
ずれも使用可能であり、具体的には、各種ポリエチレン
やポリプロピレン等が好ましく用いられる。The polyolefin resin adhering to the surface of the microstructure of the substrate is a hydrophobic resin having no hydrophilic group, and is unlikely to cause the above-mentioned problems relating to water absorption. As the polyolefin resin, any of those having a critical surface tension of 20 to 40 dynes / cm can be used, and specifically, various polyethylenes, polypropylenes and the like are preferably used.
【００２９】これらを基材となる多孔質膜に被覆処理す
るが、基材の重さ（wl）に対し付着したポリオレフィン
樹脂の重さ（w2）の比率（w2／（wl＋w2）、以下付着重
量比という）が、0.3 〜0.8 になるよう制御するのが好
ましい。この範囲内であると十分な親液性が得られやす
く、またこの範囲であると、基材多孔質体の孔を閉塞し
てしまうことによって、例えば電池用セパレータとして
重要な電気抵抗が高くなりすぎることもない。 電池用
セパレータとして使用する場合、特に膜抵抗値について
は、多孔質体１枚あたりの電解液（EC／DEC ＝1 ：1 ，
1 ．O M LiPF6）中の電気抵抗値が10Ω・cm2 以下と
し、70℃、90％RHの雰囲気下において24時間後の膜抵抗
値変化率が200 ％以下であることが好ましい。なお、こ
れらの測定方法は、後述の実施例の記載の通りである。These are coated on a porous membrane serving as a substrate, and the ratio of the weight (w2) of the polyolefin resin adhered to the weight (wl) of the substrate (w2 / (wl + w2)) (Referred to as ratio) is preferably controlled to be 0.3 to 0.8. Within this range, sufficient lyophilicity is easily obtained, and within this range, the pores of the porous substrate are closed, thereby increasing the electrical resistance, which is important as a battery separator, for example. Not too much. When used as a battery separator, in particular, regarding the membrane resistance value, the electrolyte (EC / DEC = 1: 1,
1. It is preferable that the electrical resistance value in OM LiPF6) be 10 Ω · cm 2 or less, and that the film resistance change rate after 24 hours in an atmosphere of 70 ° C. and 90% RH be 200% or less. In addition, these measuring methods are as described in the below-mentioned Examples.
【００３０】本発明の多孔質膜が電解液用セパレータと
して使用される場合、非水系溶媒としては、エチレンカ
ーボネート（EC）、プロピレンカーボネート等が挙げら
れる。また、溶質の種類や濃度は、電池等の種類や要求
特性に応じて適宜選択される。When the porous membrane of the present invention is used as a separator for an electrolytic solution, examples of the non-aqueous solvent include ethylene carbonate (EC) and propylene carbonate. The type and concentration of the solute are appropriately selected according to the type of the battery and the like and required characteristics.
【００３１】また、電極表面より生成、生長するリチウ
ムデンドライトとの直接接触を避けつつ、電極表面、デ
ンドライトによるセパレータの破壊を防ぐ為に、フッ素
樹脂多孔質の少なくとも片面に、ポリオレフィンからな
る多孔質体を積層することも可能である。この積層には
特に接着剤、接着層を用いる必要はなく、フッ素樹脂多
孔質体に付着したポリオレフィン樹脂が溶融し、ポリプ
ロピレンの多孔質膜との接着に寄与する。この接着には
ある程度の樹脂量が必要であり、それは上述した範囲で
あれば十分である。特に負極側にこのポリオレフィン多
孔質膜が接触する様に配置するのが望ましいが、両面に
あってもよい。ポリオレフィン多孔質膜の積層は、強度
の点からも優れている。Further, in order to avoid direct contact with the lithium dendrite generated and growing from the electrode surface, and to prevent the electrode surface and the separator from being broken by the dendrite, at least one surface of the fluororesin porous material is provided on at least one surface of a porous polyolefin material. Can also be laminated. It is not necessary to use an adhesive or an adhesive layer in this lamination, and the polyolefin resin adhered to the fluororesin porous body is melted and contributes to adhesion to the porous polypropylene film. This bonding requires a certain amount of resin, which is sufficient within the above range. In particular, the polyolefin porous membrane is desirably arranged so as to be in contact with the negative electrode side, but may be arranged on both sides. The lamination of the polyolefin porous membrane is also excellent in terms of strength.
【００３２】上記のポリオレフィン多孔質膜は、ポリプ
ロピレンからなるものが好適に用いられる。積層後の膜
物性として電池特性に影響がないものが前提である。特
に膜の電気抵抗は10Ω・cm2 以下が必要であり、温度、
湿度による経時変化が少ないことが要求される。As the above-mentioned porous polyolefin membrane, those made of polypropylene are preferably used. It is premised that the physical properties of the film after lamination do not affect the battery characteristics. In particular the electrical resistance of the membrane is required 10 [Omega · cm 2 or less, the temperature,
It is required that changes with time due to humidity are small.
【００３３】（本発明の表面処理剤）本発明の表面処理
剤は、ポリオレフィン樹脂とその溶媒とを含有し、高分
子多孔質膜の濡れ性を改善するための表面処理剤におい
て、前記ポリオレフィン樹脂は、濡れ性改善剤である低
分子量成分と、より分子量の大きい高分子量成分とを含
有してなることを特徴とするものであり、本発明の多孔
質膜の製造に好適に用いられるものである。従って、ポ
リオレフィン樹脂やその低分子量成分及び高分子量成分
は、前述の如き本発明の多孔質膜の場合と同様であり、
相違する点のみを説明する。(Surface Treatment Agent of the Present Invention) The surface treatment agent of the present invention comprises a polyolefin resin and a solvent thereof, and is a surface treatment agent for improving the wettability of a polymer porous membrane. Is characterized by containing a low molecular weight component as a wettability improver and a high molecular weight component having a higher molecular weight, and is preferably used for producing the porous membrane of the present invention. is there. Therefore, the polyolefin resin and its low molecular weight component and high molecular weight component are the same as in the case of the porous membrane of the present invention as described above,
Only the differences will be described.
【００３４】ポリオレフィン樹脂の溶媒としては、加熱
したキシレン等の炭化水素や、塩素化炭化水素などの有
機溶剤が、樹脂の種類や分子量に応じて適宜選択され
る。中でも、フッ素樹脂多孔質膜との親和性による処理
の容易さ、処理設備の簡易さ等の理由から、キシレンが
好ましい。As the solvent for the polyolefin resin, a heated hydrocarbon such as xylene or an organic solvent such as a chlorinated hydrocarbon is appropriately selected according to the type and molecular weight of the resin. Among them, xylene is preferable because of its easiness of processing due to affinity with the fluororesin porous membrane and simplicity of processing equipment.
【００３５】ポリオレフィン樹脂の濃度は、前記のよう
な付着量とするために適宜濃度を調整することによっ
て、基材への付着量を調整することができる。The concentration of the polyolefin resin can be adjusted to an amount as described above, whereby the amount of adhesion to the substrate can be adjusted by appropriately adjusting the concentration.
【００３６】（本発明の表面処理方法）本発明の表面処
理方法は、前記の表面処理剤を高分子多孔質膜に接触・
保持させた状態で、前記溶媒を除去して、前記ポリオレ
フィン樹脂を前記高分子多孔質膜の微細組織表面に付着
させるものであり、本発明の多孔質膜の製造に好適に用
いられるものである。従って、表面処理剤の成分や組成
等は、前述の通りであり、相違する点のみを説明する。(Surface Treatment Method of the Present Invention) In the surface treatment method of the present invention, the surface treatment agent is brought into contact with a polymer porous membrane.
In the held state, the solvent is removed, and the polyolefin resin is adhered to the surface of the microstructure of the polymer porous membrane, and is preferably used for producing the porous membrane of the present invention. . Therefore, the components and compositions of the surface treatment agent are as described above, and only the differences will be described.
【００３７】表面処理剤をフッ素樹脂多孔質膜に接触・
保持させる方法としては、浸漬法、スプレー等による塗
布等が好適なものとして挙げられるが、溶媒成分の揮発
を少なくする観点より、浸漬法が好適に用いられる。上
記のような表面処理剤を用いることにより、フッ素樹脂
多孔質膜との接触によって毛管現象により内部に処理剤
を浸透させることができる。The surface treatment agent is brought into contact with the fluororesin porous membrane.
As a method of holding the liquid, a dipping method, application by spraying or the like is preferable, but a dipping method is preferably used from the viewpoint of reducing the volatilization of the solvent component. By using the surface treatment agent as described above, the treatment agent can be penetrated into the inside by capillary action due to contact with the fluororesin porous membrane.
【００３８】また、溶媒の除去方法としては、各種の乾
燥方法や溶剤抽出法が挙げられ、乾燥温度や時間など
は、溶媒の種類などに応じて、適宜設定される。なお、
キシレン等の溶媒をエチルアルコール等の蒸発し易い溶
媒で置換することにより、膜表面に乾燥皮膜が生じて微
細孔が塞がれるのを防止することが容易となる。Examples of the method of removing the solvent include various drying methods and solvent extraction methods. The drying temperature and time are appropriately set according to the type of the solvent. In addition,
By substituting a solvent such as xylene with a solvent that easily evaporates such as ethyl alcohol, it is easy to prevent a dry film from forming on the film surface and closing the micropores.
【００３９】[0039]
【実施例】以下に本発明の具体的な構成と効果を示す実
施例について説明する。DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment showing the specific structure and effect of the present invention will be described below.
【００４０】（実施例１）フッ素樹脂多孔質膜として日
東電工社製ＮＴＦ−１０３３（厚み15μm 、空孔率90
％、孔径3.0 μm ）を用い、粘度平均分子量2000のポリ
エチレンワックスと粘度平均分子量200000の高密度ポリ
エチレン（HDPE）を5 ：5 に混合し（高分子量成分：５
０重量％）、100 ℃のキシレンに３重量％溶解した溶液
に60秒浸漬させた後、エタノール中に浸漬置換したのち
風乾し、付着重量比が０．４の膜を得た。次に、電解液
としてEC：DEC ＝1 ：1.1 M LiPF6 を用い、ヒューレッ
ドパッカード社製4262ALCRメータで10KHz の交流での膜
初期抵抗を測定したところ８Ω・cm2 であった。次に、
膜の四方を固定し70℃、90％RHの雰囲気下にて24時間静
置し、先と同様に交流抵抗を測定した。Example 1 Nitto Denko Corporation's NTF-1033 (thickness: 15 μm, porosity: 90) was used as a fluororesin porous membrane.
%, Pore diameter of 3.0 μm), and a 5: 5 mixture of polyethylene wax having a viscosity average molecular weight of 2,000 and high density polyethylene (HDPE) having a viscosity average molecular weight of 200,000 (high molecular weight component: 5
(0% by weight), and immersed in a solution of 3% by weight in xylene at 100 ° C. for 60 seconds, immersed and replaced in ethanol, and air-dried to obtain a film having an adhesion weight ratio of 0.4. Next, using EC: DEC = 1: 1.1 M LiPF 6 as an electrolyte, the initial resistance of the film was measured at 10 KHz with a 4262ALCR meter manufactured by Hewlett-Packard Company, and found to be 8 Ω · cm 2 . next,
The four sides of the film were fixed and allowed to stand for 24 hours in an atmosphere of 70 ° C. and 90% RH, and the AC resistance was measured in the same manner as above.
【００４１】（実施例２）ＮＴＦ−１０３３を用い、実
施例1 と同じ方法で作成した5 重量％キシレン溶液に12
0 秒浸漬させた後、エタノール中に浸漬置換したのち風
乾し、付着重量比が０．７、膜抵抗値４Ω・cm2 の膜を
得た。(Example 2) 12% was added to a 5% by weight xylene solution prepared in the same manner as in Example 1 using NTF-1033.
After immersion for 0 seconds, the membrane was immersed and replaced in ethanol and air-dried to obtain a membrane having an adhesion weight ratio of 0.7 and a membrane resistance value of 4 Ω · cm 2 .
【００４２】（実施例３）ＮＴＦ−１０３３を用い、同
様な方法で得た３重量％キシレン溶液に90秒浸漬させた
後、エタノール中に浸漬置換したのち風乾し、付着重量
比０．５、膜抵抗値６Ω・cm2 の膜を得た。(Example 3) Using NTF-1033, immersion was carried out for 90 seconds in a 3% by weight xylene solution obtained by the same method, followed by immersion replacement in ethanol, air-drying, and an adhesion weight ratio of 0.5. A film having a film resistance value of 6 Ω · cm 2 was obtained.
【００４３】（実施例４)ＮＴＦ−１０３３を用い、粘
度平均分子量2000のポリエチレンワックスと粘度平均分
子量200000のHDPEを9 ：1 に混合し（高分子量成分：１
０重量％）、実施例3 と同様の方法により、付着重量比
０．５、膜抵抗値３Ω・cm2 の膜を得た。Example 4 Using NTF-1033, polyethylene wax having a viscosity average molecular weight of 2,000 and HDPE having a viscosity average molecular weight of 200,000 were mixed at a ratio of 9: 1 (high molecular weight component: 1).
0% by weight) and in the same manner as in Example 3, a film having an adhesion weight ratio of 0.5 and a film resistance value of 3 Ω · cm 2 was obtained.
【００４４】（実施例５）ＮＴＦ−１０３３を用い、粘
度平均分子量2000のポリエチレンワックスと粘度平均分
子量200000のHDPEを6 ：4 に混合し（高分子量成分：４
０重量％）、実施例３と同様の方法により、付着重量比
０．５、膜抵抗値４Ω・cm2 の膜を得た。Example 5 Using NTF-1033, polyethylene wax having a viscosity average molecular weight of 2,000 and HDPE having a viscosity average molecular weight of 200,000 were mixed at a ratio of 6: 4 (high molecular weight component: 4).
0% by weight) and a film having an adhesion weight ratio of 0.5 and a film resistance value of 4 Ω · cm 2 was obtained in the same manner as in Example 3.
【００４５】（実施例６）実施例３の方法により、付着
重量比０．５、膜抵抗値６Ω・cm2 のフッ素樹脂多孔質
膜を得、さらにポリプロピレンからなる気孔率45％、厚
さ15μm 、通気度100sec／100cc の多孔質膜を120 ℃の
熱ロール上にて貼り合わせ、層厚20μm 、通気度400sec
／100cc 、膜抵抗値６Ω・cm2 の２層膜を得た。Example 6 By the method of Example 3, a fluororesin porous membrane having an adhesion weight ratio of 0.5 and a membrane resistance value of 6 Ω · cm 2 was obtained, and further, a porosity of 45% made of polypropylene and a thickness of 15 μm , A porous film with air permeability of 100 sec / 100 cc is stuck on a heat roll at 120 ° C., layer thickness 20 μm, air permeability of 400 sec.
/ 100 cc, and a two-layer film having a film resistance value of 6 Ω · cm 2 was obtained.
【００４６】（比較例１）ＮＴＦ−１０３３の膜を、フ
ッ素系界面活性剤であるユニダイン（DS401 ）２重量％
アルコール溶液に120 秒浸漬させ、その後60℃の熱槽に
てアルコールを除去し、界面活性剤処理したフッ素樹脂
多孔質膜を得た。この膜の通気度は3sec／100cc 、膜抵
抗値は1.2 Ω・cm2 であった。(Comparative Example 1) A film of NTF-1033 was prepared by adding 2% by weight of Unidyne (DS401) which is a fluorine-based surfactant.
It was immersed in an alcohol solution for 120 seconds, and then the alcohol was removed in a heat bath at 60 ° C. to obtain a fluororesin porous membrane treated with a surfactant. The air permeability of this membrane was 3 sec / 100 cc, and the membrane resistance was 1.2 Ω · cm 2 .
【００４７】（比較例２）ＮＴＦ−１０３３を用い、粘
度平均分子量2000のポリエチレンワックスを100℃のキ
シレンに３重量％溶解した溶液に90秒浸漬させた後、エ
タノール中に浸漬置換したのち風乾し、付着重量比０．
５、膜抵抗値４Ω・cm２の膜を得た。Comparative Example 2 Using NTF-1033, a polyethylene wax having a viscosity-average molecular weight of 2,000 was immersed in a solution of 3% by weight in xylene at 100 ° C. for 90 seconds, then immersed and replaced in ethanol, and air-dried. , Adhering weight ratio 0.
5. A film having a film resistance value of 4Ω · cm 2 was obtained.
【００４８】（比較例３）比較例１により得られた膜に
ポリエチレン及びポリプロピレンからなる、気孔率45
％、通気度200sec／100cc 、厚さ20μm の多孔質膜を、
ポリエチレンとＮＴＦ−１０３３が接触するように120
℃熱ロール上で貼り合わせた。積層膜の通気度は350sec
／100cc 、膜抵抗値は３Ω・cm2 であった。Comparative Example 3 A porosity of 45 consisting of polyethylene and polypropylene was applied to the film obtained in Comparative Example 1.
%, Air permeability of 200sec / 100cc, thickness of 20μm,
120 so that polyethylene and NTF-1033 are in contact.
The film was stuck on a hot roll. The air permeability of the laminated film is 350sec
/ 100cc, and the film resistance was 3Ω · cm 2 .
【００４９】（参考例１）ＮＴＦ−１０３３を用い、粘
度平均分子量2000のポリエチレンワックスと粘度平均分
子量200000のHDPEを2 ：8 に混合し（高分子量成分：８
０重量％）、100℃のキシレンに重量％溶解した溶液に9
0秒浸漬させた後乾燥させ、エタノール中に浸漬置換し
たのち風乾し、付着重量比０．５、膜抵抗値３Ω・cm2
の膜を得た。Reference Example 1 Using NTF-1033, a polyethylene wax having a viscosity average molecular weight of 2,000 and HDPE having a viscosity average molecular weight of 200,000 were mixed in a ratio of 2: 8 (high molecular weight component: 8).
0% by weight), and 9% by weight dissolved in xylene at 100 ° C.
After immersion for 0 seconds, drying, immersion replacement in ethanol and air drying, adhesion weight ratio of 0.5, membrane resistance value of 3Ω · cm 2
Was obtained.
【００５０】以上の実施例等の結果を表１に示す。Table 1 shows the results of the above examples and the like.
【００５１】[0051]
【表１】 表１の結果が示すように、実施例の多孔質膜によると、
低分子量成分の機能を損なうことなく、その脱落の防止
できた結果、いずれも膜抵抗変化率が小さく、電解液に
対する濡れ性が維持できた。[Table 1] As shown in the results of Table 1, according to the porous membrane of the example,
As a result of preventing the falling of the low molecular weight component without impairing the function thereof, the rate of change in the film resistance was small in each case, and the wettability to the electrolytic solution could be maintained.
【００５２】これに対して、界面活性剤処理を行ったも
の（比較例１）、低分子量成分のみを用いたもの（比較
例２）、界面活性剤処理を行ったものにポリオレフィン
多孔質膜を積層したもの（比較例３）では、いずれも低
分子量成分の脱落は防止できず、その結果、いずれも膜
抵抗変化率が大きく、電解液に対する濡れ性が維持でき
なかった。また、高分子量成分の混合量が適性でないも
の（参考例１）では、膜抵抗変化率がやや大きいもの
の、低分子量成分のみを用いたもの（比較例２）と比較
して、その値が改善されており、本発明の効果が得られ
ていることが分かる。On the other hand, the polyolefin porous membrane was treated with a surfactant (Comparative Example 1), with only a low molecular weight component (Comparative Example 2), and with a surfactant. In the case of the laminated structure (Comparative Example 3), none of the low molecular weight components could be prevented from falling off. As a result, the film resistance change rate was large and the wettability to the electrolytic solution could not be maintained. In addition, in the case where the mixing amount of the high molecular weight component was not appropriate (Reference Example 1), the value was improved as compared with the case where only the low molecular weight component was used (Comparative Example 2), although the rate of change in film resistance was slightly large. It can be seen that the effect of the present invention has been obtained.
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 ＦＩ Ｈ０１Ｇ 9/02 ３０１ Ｈ０１Ｇ 9/00 ３０１Ｃ (72)発明者 石崎 哲 大阪府茨木市下穂積１丁目１番２号 日東 電工株式会社内──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. 6 Identification symbol FI H01G 9/02 301 H01G 9/00 301C (72) Inventor Tetsu Ishizaki 1-2-1, Shimohozumi, Ibaraki-shi, Osaka Nitto Denko Corporation In company
Claims (7)
面に、ポリオレフィン樹脂が付着してなる多孔質膜にお
いて、 前記ポリオレフィン樹脂は、濡れ性改善剤である低分子
量成分に対して、より分子量の大きい高分子量成分が、
均質に混合されていることを特徴とする多孔質膜。1. A porous film in which a polyolefin resin is adhered to a fine structure surface of a polymer porous film serving as a base material, wherein the polyolefin resin has a low molecular weight component as a wettability improving agent. Higher molecular weight components with higher molecular weight
A porous membrane characterized by being homogeneously mixed.
000 以下のポリエチレンであり、前記高分子量成分が粘
度平均分子量20000 〜350000のポリエチレンである請求
項１記載の多孔質膜。2. The low-molecular-weight component has a viscosity average molecular weight of 10
2. The porous membrane according to claim 1, wherein the high molecular weight component is polyethylene having a viscosity average molecular weight of 20,000 to 350,000.
オレフィン樹脂中の５〜６０重量％である請求項１又は
２に記載の多孔質膜。3. The porous membrane according to claim 1, wherein the content of the high molecular weight component is 5 to 60% by weight in the polyolefin resin.
質膜である請求項１〜３いずれかに記載の多孔質膜。4. The porous membrane according to claim 1, wherein the polymer porous membrane is a fluororesin porous membrane.
る請求項１〜４いずれかに記載の多孔質膜。5. The porous membrane according to claim 1, which is used as a separator for a non-aqueous electrolyte.
し、高分子多孔質膜の濡れ性を改善するための表面処理
剤において、 前記ポリオレフィン樹脂は、濡れ性改善剤である低分子
量成分と、より分子量の大きい高分子量成分とを含有し
てなることを特徴とする表面処理剤。6. A surface treatment agent for improving the wettability of a porous polymer membrane, comprising a polyolefin resin and a solvent thereof, wherein the polyolefin resin comprises a low molecular weight component as a wettability improver. A surface treating agent comprising a high molecular weight component having a high molecular weight.
質膜に接触・保持させた状態で、前記溶媒を除去して、
前記ポリオレフィン樹脂を前記高分子多孔質膜の微細組
織表面に付着させる表面処理方法。7. The solvent is removed while the surface treating agent according to claim 6 is in contact with and held by the polymer porous membrane,
A surface treatment method for attaching the polyolefin resin to the surface of the microstructure of the polymer porous membrane.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10095943A JPH11297296A (en) | 1998-04-08 | 1998-04-08 | Porous film, surface treatment agent and surface treatment method |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10095943A JPH11297296A (en) | 1998-04-08 | 1998-04-08 | Porous film, surface treatment agent and surface treatment method |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH11297296A true JPH11297296A (en) | 1999-10-29 |
Family
ID=14151356
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10095943A Pending JPH11297296A (en) | 1998-04-08 | 1998-04-08 | Porous film, surface treatment agent and surface treatment method |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH11297296A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010123381A (en) * | 2008-11-19 | 2010-06-03 | Tdk Corp | Lithium-ion secondary battery separator and lithium-ion secondary battery |
| CN102941021A (en) * | 2012-11-06 | 2013-02-27 | 南京工业大学 | Preparation method of low molecular weight cutoff (MWCO) ZrO2 nanofiltration membrane |
-
1998
- 1998-04-08 JP JP10095943A patent/JPH11297296A/en active Pending
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2010123381A (en) * | 2008-11-19 | 2010-06-03 | Tdk Corp | Lithium-ion secondary battery separator and lithium-ion secondary battery |
| CN102941021A (en) * | 2012-11-06 | 2013-02-27 | 南京工业大学 | Preparation method of low molecular weight cutoff (MWCO) ZrO2 nanofiltration membrane |
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