JP2005216992A - Separator for capacitor - Google Patents
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- JP2005216992A JP2005216992A JP2004019365A JP2004019365A JP2005216992A JP 2005216992 A JP2005216992 A JP 2005216992A JP 2004019365 A JP2004019365 A JP 2004019365A JP 2004019365 A JP2004019365 A JP 2004019365A JP 2005216992 A JP2005216992 A JP 2005216992A
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- 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
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- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
- Y02E60/13—Energy storage using capacitors
Abstract
Description
本発明は、各種電子機器のバックアップ電源や電気自動車の補助電源、無停電電源装置等に使用される電気二重層キャパシタや電解コンデンサに代表される電解液を使用したコンデンサ用セパレータに関するものである。 The present invention relates to a separator for a capacitor using an electrolytic solution typified by an electric double layer capacitor and an electrolytic capacitor used in a backup power source for various electronic devices, an auxiliary power source for an electric vehicle, an uninterruptible power supply device, and the like.
微多孔質膜は、電解液を使用するコンデンサや蓄電池用のセパレータとして従来から使用されており、近年のポータブル電子機器の急速な普及に伴い、その適用範囲と需要が拡大している。近年では、長寿命、急速充放電が可能、メンテナンスが不要などの優れた特長からコンデンサが注目されており、特に、容量が大きい電気二重層キャパシタの需要が増加している。
電気二重層キャパシタは、主に各種電子機器のバックアップ電源等に使用されており、ポータブル電子機器類の小型化、高性能化に伴い、電気二重層キャパシタも小型化、高性能化が要求されている。そのため、セパレータには、厚さが薄く、高空隙率であり、かつ信頼性の高いことが要求されている。
Microporous membranes have been used in the past as capacitors for electrolytic solutions and separators for storage batteries, and their application range and demand are expanding with the rapid spread of portable electronic devices in recent years. In recent years, capacitors have attracted attention due to their excellent features such as long life, rapid charge / discharge, and no maintenance required. In particular, demand for electric double layer capacitors having a large capacity is increasing.
Electric double layer capacitors are mainly used as backup power sources for various electronic devices. As portable electronic devices become smaller and higher in performance, electric double layer capacitors are also required to be smaller and higher in performance. Yes. Therefore, the separator is required to be thin, have a high porosity, and have high reliability.
電気二重層キャパシタは、水溶液系電解液を使用するタイプと、有機系電解液を使用するタイプの２種類に大別される。水溶液系電解液を使用するタイプの場合、主に電解液に硫酸が使われており、セパレータとして、一般に、耐酸性のあるポリオレフィン系樹脂をベースとした微多孔質膜が使用されている（例えば、特許文献１）。
一方、有機系電解液を使用するタイプの場合は、セパレータに耐酸性が要求されないため、繊維材料からなる不織布が一般に使用されている。繊維材料からなる不織布は、安価であり経済性に優れる特徴を持つ反面、孔径が大きいため、電気二重層キャパシタの信頼性や自己放電の面で劣る欠点がある。これを改善するため、有機系電解液を使用するタイプであっても、前述したような水溶液系電解液を使用するタイプで一般に使用されている、無機粉体を含有させたポリオレフィン系微多孔質膜を適用することが考えられる。有機系電解液は水溶液系電解液に比べ電解液の電気抵抗が高いため、水溶液系電解液を使用するタイプで用いるセパレータよりも、より薄く、より空隙率の高いセパレータとする必要がある。例えば、セパレータの空隙率を高めるには、開孔剤である原料組成物中の可塑剤の配合量を増量することで可能である。また、セパレータを薄くするには、押出成形後のシートを圧延・延伸等の二次加工を行うことで可能である。
On the other hand, in the case of a type using an organic electrolytic solution, a non-woven fabric made of a fiber material is generally used because the separator does not require acid resistance. Nonwoven fabric made of a fiber material is inexpensive and excellent in economic efficiency, but has a large pore size, and therefore has a disadvantage that it is inferior in terms of reliability and self-discharge of the electric double layer capacitor. In order to improve this, polyolefin type microporous material containing inorganic powder, which is generally used in the type using aqueous electrolytic solution as described above, even if it is a type using organic electrolytic solution It is conceivable to apply a membrane. Since the organic electrolyte has higher electric resistance than the aqueous electrolyte, it is necessary to make the separator thinner and higher in porosity than the separator used in the type using the aqueous electrolyte. For example, the porosity of the separator can be increased by increasing the blending amount of the plasticizer in the raw material composition which is a pore opening agent. In addition, the separator can be thinned by subjecting the extruded sheet to secondary processing such as rolling and stretching.
しかしながら、無機粉体を含有させたポリオレフィン系微多孔質膜からなる薄膜のセパレータを得ようとする場合、押出成形後のシートに対して圧延・延伸等の二次加工（薄肉化処理）を行った際に、該シート中の無機粉体に起因するピンホールのような欠点（欠陥部）が生じ易く、製品歩留りの低下を招き、また、安定した品質を確保することが難しかった。
そこで、本発明は、上記従来の問題点に鑑み、ポリオレフィン系樹脂と無機粉体を主体とした微多孔質膜からなるコンデンサ用セパレータにおいて、高空隙率であり、かつ薄肉化した場合でもピンホールのような欠点の少ないコンデンサ用セパレータを提供することを目的とする。
However, when trying to obtain a thin film separator made of a polyolefin microporous membrane containing inorganic powder, secondary processing (thinning treatment) such as rolling and stretching is performed on the extruded sheet. In such a case, defects (defects) such as pinholes caused by the inorganic powder in the sheet are likely to occur, resulting in a decrease in product yield, and it is difficult to ensure stable quality.
Therefore, in view of the above-described conventional problems, the present invention provides a capacitor separator composed of a microporous film mainly composed of a polyolefin resin and an inorganic powder, and has a high porosity and even a thin pinhole. It aims at providing the separator for capacitors with few such faults.
本発明のコンデンサ用セパレータは、前記目的を達成するべく、請求項１に記載の通り、ポリオレフィン系樹脂、無機粉体および可塑剤を主体とした原料組成物を加熱溶融してシート状に押出成形し、圧延・延伸等の薄肉化処理を行い、前記可塑剤を除去して得られた微多孔質膜からなるコンデンサ用セパレータにおいて、前記無機粉体の含水率が３質量％以下であり、前記無機粉体の最大粒子径Ａと膜厚Ｔの関係Ａ／Ｔが０．５以下であることを特徴とする。
また、請求項２記載のコンデンサ用セパレータは、請求項１記載のコンデンサ用セパレータにおいて、前記関係Ａ／Ｔが０．４以下であることを特徴とする。
また、請求項３記載のコンデンサ用セパレータは、請求項１または２に記載のコンデンサ用セパレータにおいて、空隙率が７０％以上であり、膜厚が２５〜１００μｍであることを特徴とする。
また、請求項４記載のコンデンサ用セパレータは、請求項１乃至３のいずれかに記載のコンデンサ用セパレータにおいて、前記ポリオレフィン系樹脂の含有量が２０〜４０質量％、前記無機粉体の含有量が６０〜８０質量％であることを特徴とする。
また、請求項５記載のコンデンサ用セパレータは、請求項３または４記載のコンデンサ用セパレータにおいて、有機系電解液を使用した電気二重層キャパシタ用セパレータであることを特徴とする。
In order to achieve the above object, the capacitor separator of the present invention, as described in claim 1, heat-melts a raw material composition mainly composed of a polyolefin resin, an inorganic powder and a plasticizer, and extrudes it into a sheet shape. In a capacitor separator comprising a microporous film obtained by performing thinning treatment such as rolling and stretching, and removing the plasticizer, the water content of the inorganic powder is 3% by mass or less, The relation A / T between the maximum particle diameter A and the film thickness T of the inorganic powder is 0.5 or less.
The capacitor separator according to claim 2 is the capacitor separator according to claim 1, wherein the relationship A / T is 0.4 or less.
The capacitor separator according to claim 3 is the capacitor separator according to claim 1 or 2, characterized in that the porosity is 70% or more and the film thickness is 25 to 100 μm.
The capacitor separator according to claim 4 is the capacitor separator according to any one of claims 1 to 3, wherein the content of the polyolefin-based resin is 20 to 40% by mass, and the content of the inorganic powder is 60 to 80% by mass.
The capacitor separator according to claim 5 is the capacitor separator according to claim 3 or 4, wherein the capacitor separator is an electric double layer capacitor separator using an organic electrolyte.
本発明によれば、ポリオレフィン系樹脂、無機粉体および可塑剤を主体とした原料組成物を加熱溶融してシート状に押出成形し、圧延・延伸等の薄肉化処理を行い、前記可塑剤を除去して得られた微多孔質膜からなるコンデンサ用セパレータにおいて、前記無機粉体の含水率を３質量％以下とし、かつ前記無機粉体の最大粒子径Ａと膜厚Ｔの関係Ａ／Ｔを０．５以下としたことで、押出成形後のシート中に、無機粉体の比較的大きな粒子や凝集塊を混在させないようにすることができるので、より薄膜のセパレータを得ようとする場合であっても、無機粉体に起因するピンホールのような欠点の少ないコンデンサ用セパレータを提供することができ、製品歩留りの向上と安定した品質の確保をもたらすことができるもので、特に、有機系電解液を使用した電気二重層キャパシタ用セパレータとして用いた場合に有用性が高い。 According to the present invention, a raw material composition mainly composed of polyolefin resin, inorganic powder and plasticizer is heated and melted and extruded into a sheet, and subjected to thinning treatment such as rolling and stretching. In the capacitor separator comprising the microporous film obtained by removing, the water content of the inorganic powder is 3% by mass or less, and the relationship between the maximum particle diameter A and the film thickness T of the inorganic powder is A / T. When it is set to 0.5 or less, it is possible to prevent relatively large particles or agglomerates of the inorganic powder from being mixed in the sheet after extrusion molding, so when obtaining a thinner separator Even so, it is possible to provide a capacitor separator with few defects such as pinholes caused by inorganic powder, which can improve the product yield and ensure stable quality. Electrolysis Highly useful when used as an electric double layer separators for capacitors was used.
本発明のコンデンサ用セパレータを得るための原料組成物の主成分は、ポリオレフィン系樹脂と無機粉体および可塑剤である。尚、セパレータの用途、つまり、セパレータを適用するコンデンサの種類によっては、濡れ性を確保するための界面活性剤をさらに配合してもよい。通常、有機系電解液を使用するコンデンサに適用する場合は、有機系電解液に対して元々十分な濡れ性を有しているので界面活性剤の配合は不要であるが、水溶液系電解液を使用するコンデンサに適用する場合は、界面活性剤を配合し水溶液系電解液に対する濡れ性を確保することが好ましい。 The main components of the raw material composition for obtaining the capacitor separator of the present invention are a polyolefin resin, an inorganic powder, and a plasticizer. Depending on the application of the separator, that is, the type of capacitor to which the separator is applied, a surfactant for ensuring wettability may be further blended. Normally, when applied to a capacitor using an organic electrolyte, it does not need a surfactant because it originally has sufficient wettability with respect to the organic electrolyte. When applied to a capacitor to be used, it is preferable to add a surfactant to ensure wettability with respect to an aqueous electrolyte.
前記ポリオレフィン系樹脂としては、ポリエチレン、ポリプロピレン、ポリブテンおよびこれらの共重合物あるいは混合物が使用できる。特に、重量平均分子量１００万以上の高密度ポリエチレンを使用すれば、機械的強度の優れた微多孔質膜を得ることができる。また、重量平均分子量の異なる樹脂を混合使用することも可能であり、例えば、重量平均分子量２００万以上の高密度ポリエチレンと重量平均分子量２０万未満の低密度ポリエチレンをブレンドして使用することもできる。
前記セパレータ中の前記ポリオレフィン系樹脂の含有量は、２０〜４０質量％が好ましい。ポリオレフィン系樹脂の含有量が２０質量％未満であると、ポリオレフィン系樹脂がセパレータ全体に均一に分散できず機械的強度が著しく低下するため好ましくなく、４０質量％を超えると、相対的に無機粉体の含有量が少なくなりセパレータの耐熱性が低下するため好ましくない。
As the polyolefin resin, polyethylene, polypropylene, polybutene and copolymers or mixtures thereof can be used. In particular, if a high density polyethylene having a weight average molecular weight of 1,000,000 or more is used, a microporous film having excellent mechanical strength can be obtained. It is also possible to use a mixture of resins having different weight average molecular weights. For example, a high density polyethylene having a weight average molecular weight of 2 million or more and a low density polyethylene having a weight average molecular weight of less than 200,000 can be blended and used. .
The content of the polyolefin resin in the separator is preferably 20 to 40% by mass. If the polyolefin resin content is less than 20% by mass, the polyolefin resin cannot be uniformly dispersed throughout the separator and the mechanical strength is significantly reduced. This is not preferable because the content of the body is reduced and the heat resistance of the separator is lowered.
前記無機粉体としては、以下の条件を満たす、シリカ、アルミナ、チタニア、炭酸カルシウム等の１種または２種以上が使用できる。
前記無機粉体は、粉体の最大粒子径Ａ（μｍ）とセパレータの膜厚Ｔ（μｍ）の関係Ａ／Ｔが０．５以下となるような粒子径を有している必要があり、より好ましくは、０．４以下である。Ａ／Ｔを０．５以下とすることで、押出成形後のシート中に、無機粉体の比較的大きな粒子や凝集塊を混在させないようにすることができ、圧延・延伸等の薄肉化処理によってより薄膜のセパレータを得ようとする場合であっても、無機粉体に起因するピンホール等の欠点の発生を抑えることができ、Ａ／Ｔが０．４以下であれば、さらに効果が高い。
前記無機粉体の含水率は３質量％以下である必要がある。含水率が３質量％を超えると、無機粉体が凝集し易くなって大きな凝集体を作り易くなり、押出成形後のシート中に、無機粉体の比較的大きな凝集塊を混在させ易くなり、圧延・延伸等の薄肉化処理によってより薄膜のセパレータを得ようとする場合に、無機粉体に起因するピンホール等の欠点を発生し易くするので好ましくない。
As the inorganic powder, one or more of silica, alumina, titania, calcium carbonate and the like that satisfy the following conditions can be used.
The inorganic powder must have a particle size such that the relationship A / T between the maximum particle size A (μm) of the powder and the film thickness T (μm) of the separator is 0.5 or less, More preferably, it is 0.4 or less. By setting A / T to 0.5 or less, it is possible to prevent relatively large particles or agglomerates of inorganic powder from being mixed in the sheet after extrusion, and thinning treatment such as rolling and stretching. Even if it is a case where it is a case where it is going to obtain a thin film separator by this, generation | occurrence | production of faults, such as a pinhole resulting from inorganic powder, can be suppressed, and if A / T is 0.4 or less, a further effect high.
The water content of the inorganic powder needs to be 3% by mass or less. When the water content exceeds 3% by mass, the inorganic powder easily aggregates to easily form a large aggregate, and it becomes easy to mix relatively large aggregates of the inorganic powder in the sheet after extrusion molding. In the case of obtaining a thin film separator by thinning treatment such as rolling or stretching, it is not preferable because defects such as pinholes due to inorganic powder are easily generated.
前記セパレータ中の前記無機粉体の含有量は、６０〜８０質量％が好ましい。無機粉体の含有量が６０質量％未満であると、セパレータの耐熱性が低下するため好ましくなく、８０質量％を超えると、相対的にポリオレフィン系樹脂の含有量が少なくなりポリオレフィン系樹脂がセパレータ全体に均一に分散できず機械的強度が著しく低下するため好ましくない。 The content of the inorganic powder in the separator is preferably 60 to 80% by mass. If the content of the inorganic powder is less than 60% by mass, the heat resistance of the separator is lowered, which is not preferable. If the content exceeds 80% by mass, the content of the polyolefin resin is relatively reduced, and the polyolefin resin becomes a separator. This is not preferable because it cannot be uniformly dispersed throughout and the mechanical strength is significantly reduced.
前記可塑剤としては、パラフィン系、ナフテン系等の工業用潤滑油や、フタル酸ジオクチル等のエステル系可塑剤が使用できる。 As the plasticizer, industrial lubricating oils such as paraffinic and naphthenic esters and ester plasticizers such as dioctyl phthalate can be used.
前記界面活性剤としては、アルキルスルホコハク酸塩やナフタリンスルホン酸塩ホルマリン縮合物等のアニオン系またはポリオキシエチレンアルキルエーテル等のノニオン系の単独または混合物が使用できる。界面活性剤の添加量は、前記したポリオレフィン系樹脂と無機粉体および可塑剤を主成分とする原料組成物に対して、０．５〜１０外質量％が好ましい。界面活性剤の添加量が０．５外質量％未満であると、実質的な濡れ性の向上効果が得られないため好ましくなく、１０外質量％を超えると、界面活性剤が電解液中に溶け出し電極に付着してコンデンサの寿命性能に悪影響を与えるため好ましくない。 As the surfactant, anionic compounds such as alkylsulfosuccinates and naphthalenesulfonate formalin condensates or nonionic compounds such as polyoxyethylene alkyl ethers can be used alone or in a mixture. The addition amount of the surfactant is preferably 0.5 to 10% by mass with respect to the raw material composition mainly composed of the polyolefin resin, the inorganic powder, and the plasticizer. If the addition amount of the surfactant is less than 0.5% by mass, it is not preferable because a substantial improvement in wettability cannot be obtained. If the amount exceeds 10% by mass, the surfactant is contained in the electrolyte. It is not preferable because it adheres to the melted electrode and adversely affects the life performance of the capacitor.
前記セパレータは、空隙率が７０％以上と高空隙率であることが好ましい。これにより、前記セパレータの内部抵抗を低減することができ、特に、電解液の抵抗が比較的高い有機系電解液を使用した電気二重層キャパシタに用いるコンデンサ用セパレータとして好適に用いることが可能となる。 The separator preferably has a high porosity of 70% or more. Thereby, the internal resistance of the separator can be reduced, and in particular, it can be suitably used as a capacitor separator used in an electric double layer capacitor using an organic electrolyte having a relatively high resistance of the electrolyte. .
前記セパレータの厚さ（膜厚）は、２５〜１００μｍが好ましい。厚さが２５μｍ未満であると、セパレータとしての隔離効果が小さくコンデンサの寿命性能に悪影響を与えたり、製造時に欠点を発生し易くなるため好ましくなく、１００μｍを超えると、電気抵抗が高くなりコンデンサの内部抵抗を高めるため好ましくない。 The thickness (film thickness) of the separator is preferably 25 to 100 μm. If the thickness is less than 25 μm, it is not preferable because the isolation effect as a separator is small and adversely affects the life performance of the capacitor, and defects are likely to occur during manufacturing. This is not preferable because the internal resistance is increased.
本発明のコンデンサ用セパレータは、例えば、次のような方法によって得ることができる。前記ポリオレフィン系樹脂、前記無機粉体、前記可塑剤と、必要に応じて前記界面活性剤をレーディゲミキサ等で混合し、該混合物（原料組成物）を、押出成形機を用いて加熱溶融・混練しながらシート状に押出成形し、圧延・延伸等の二次加工によって薄肉化処理を行い、所定厚さのシートを得る。次いで、該シート中の可塑剤を、適当な抽出溶剤を用いて抽出除去し、乾燥および必要に応じてアニーリングすれば、本発明のコンデンサ用セパレータが得られる。 The capacitor separator of the present invention can be obtained, for example, by the following method. The polyolefin resin, the inorganic powder, the plasticizer and, if necessary, the surfactant are mixed by a Ladige mixer or the like, and the mixture (raw material composition) is heated, melted and kneaded using an extruder. While extruding into a sheet shape, a thinning process is performed by secondary processing such as rolling and stretching to obtain a sheet having a predetermined thickness. Subsequently, the plasticizer in the sheet is extracted and removed using an appropriate extraction solvent, dried and annealed as necessary, so that the capacitor separator of the present invention is obtained.
次に、本発明の実施例について比較例と共に詳細に説明する。
（実施例１）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部（質量部、以下同じ）と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、無機粉体として最大粒子径１５μｍ、含水率１．１質量％のシリカ粉体１９０部、可塑剤としてパラフィン系オイル４２０部をレーディゲミキサで混合し、先端にＴダイを取り付けた二軸押出成形機で加熱溶融・混練しながらシート状に押出成形し、次いで成形ロールにて圧延処理（薄肉化処理１）して厚さ１３０μｍのシートを得た。次に、このシートを一軸方向に延伸処理（薄肉化処理２）した後、前記可塑剤を有機溶剤で抽出除去し、加熱乾燥して、ポリエチレン樹脂３４質量％とシリカ粉体６６質量％で構成される厚さ４０μｍの微多孔質膜からなるコンデンサ用セパレータを得た。
Next, examples of the present invention will be described in detail together with comparative examples.
(Example 1)
70 parts (parts by mass) of high density polyethylene resin powder having a weight average molecular weight of 2 million as a polyolefin-based resin, 30 parts of high density polyethylene resin powder having a weight average molecular weight of 200,000, and a maximum particle diameter of 15 μm as an inorganic powder , 190 parts of silica powder with a water content of 1.1% by mass, 420 parts of paraffinic oil as a plasticizer are mixed with a Ladige mixer, and heated and melted and kneaded with a twin screw extruder with a T die attached to the tip. And then rolled (thinning treatment 1) with a forming roll to obtain a sheet having a thickness of 130 μm. Next, this sheet was stretched in a uniaxial direction (thinning treatment 2), and then the plasticizer was extracted and removed with an organic solvent and dried by heating to constitute 34% by mass of polyethylene resin and 66% by mass of silica powder. A capacitor separator made of a microporous film having a thickness of 40 μm was obtained.
（実施例２）
実施例１と同様の材料をレーディゲミキサで混合し、先端にＴダイを取り付けた二軸押出成形機で加熱溶融・混練しながらシート状に押出成形し、次いで成形ロールにて圧延処理（薄肉化処理１）して厚さ１１０μｍのシートを得た。次に、このシートを一軸方向に延伸処理（薄肉化処理２）した後、前記可塑剤を有機溶剤で抽出除去し、加熱乾燥して、ポリエチレン樹脂３４質量％とシリカ粉体６６質量％で構成される厚さ３０μｍの微多孔質膜からなるコンデンサ用セパレータを得た。
(Example 2)
The same materials as in Example 1 were mixed with a Ladige mixer, extruded into a sheet shape while being heated and melted and kneaded with a twin-screw extruder with a T-die attached to the tip, and then rolled with a forming roll (thinning treatment) 1) to obtain a sheet having a thickness of 110 μm. Next, this sheet was stretched in a uniaxial direction (thinning treatment 2), and then the plasticizer was extracted and removed with an organic solvent and dried by heating to constitute 34% by mass of polyethylene resin and 66% by mass of silica powder. A capacitor separator made of a microporous film having a thickness of 30 μm was obtained.
（実施例３）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、無機粉体として最大粒子径３０μｍ、含水率１．１質量％のシリカ粉体１９０部、可塑剤としてパラフィン系オイル４２０部をレーディゲミキサで混合し、先端にＴダイを取り付けた二軸押出成形機で加熱溶融・混練しながらシート状に押出成形し、次いで成形ロールにて圧延処理（薄肉化処理）して厚さ１００μｍのシートを得た。次に、前記可塑剤を有機溶剤で抽出除去し、加熱乾燥して、ポリエチレン樹脂３４質量％とシリカ粉体６６質量％で構成される厚さ１００μｍの微多孔質膜からなるコンデンサ用セパレータを得た。
(Example 3)
70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million as a polyolefin resin, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, a maximum particle diameter of 30 μm, and a water content of 1.1 mass as an inorganic powder 190 parts of silica powder and 420 parts of paraffinic oil as a plasticizer are mixed with a Ladige mixer, and extruded and formed into a sheet while heating and melting and kneading with a twin screw extruder equipped with a T-die at the tip, and then molded. A roll having a thickness of 100 μm was obtained by rolling with a roll (thinning treatment). Next, the plasticizer is extracted and removed with an organic solvent and dried by heating to obtain a capacitor separator composed of a microporous film having a thickness of 100 μm and comprising 34% by mass of polyethylene resin and 66% by mass of silica powder. It was.
（実施例４）
ポリオレフィン系樹脂として重量平均分子量３００万の高密度ポリエチレン樹脂粉体１００部、無機粉体として最大粒子径１５μｍ、含水率１．１質量％のシリカ粉体２６０部、可塑剤としてパラフィン系オイル５７０部、界面活性剤としてアルキルスルホコハク酸塩１５部をレーディゲミキサで混合し、実施例１と同様にして、ポリエチレン樹脂２８質量％とシリカ粉体７２質量％とアルキルスルホコハク酸塩２外質量％（固形分）で構成される厚さ４０μｍの微多孔質膜からなるコンデンサ用セパレータを得た。
Example 4
100 parts of a high density polyethylene resin powder having a weight average molecular weight of 3 million as a polyolefin resin, 260 parts of silica powder having a maximum particle diameter of 15 μm and a water content of 1.1% by mass as an inorganic powder, and 570 parts of paraffinic oil as a plasticizer In addition, 15 parts of alkylsulfosuccinate as a surfactant was mixed with a Laedige mixer, and in the same manner as in Example 1, 28% by mass of polyethylene resin, 72% by mass of silica powder, and 2% by mass of alkylsulfosuccinate (solid content) A capacitor separator made of a microporous film having a thickness of 40 μm constituted by the following was obtained.
（実施例５）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体５０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体５０部、無機粉体として最大粒子径１５μｍ、含水率１．１質量％のシリカ粉体１００部、可塑剤としてパラフィン系オイル２２０部をレーディゲミキサで混合し、実施例１と同様にして、ポリエチレン樹脂５０質量％とシリカ粉体５０質量％で構成される厚さ４０μｍの微多孔質膜からなるコンデンサ用セパレータを得た。
(Example 5)
50 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million as a polyolefin resin, 50 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, a maximum particle diameter of 15 μm, and a water content of 1.1 mass as an inorganic powder. 100 parts by weight of silica powder and 220 parts of paraffinic oil as a plasticizer were mixed with a Ladige mixer, and in the same manner as in Example 1, a 40 μm-thickness composed of 50% by weight of polyethylene resin and 50% by weight of silica powder. A capacitor separator made of a microporous film was obtained.
（比較例１）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、無機粉体として最大粒子径２４μｍ、含水率１．１質量％のシリカ粉体１９０部、可塑剤としてパラフィン系オイル４２０部をレーディゲミキサで混合し、実施例１と同様にして、ポリエチレン樹脂３４質量％とシリカ粉体６６質量％で構成される厚さ４０μｍの微多孔質膜からなるコンデンサ用セパレータを得た。
(Comparative Example 1)
70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million as a polyolefin resin, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, a maximum particle diameter of 24 μm, and a moisture content of 1.1 mass as an inorganic powder 190 parts by weight of silica powder and 420 parts of paraffinic oil as a plasticizer were mixed by a Ladige mixer, and in the same manner as in Example 1, a 40 μm-thickness composed of 34% by weight of polyethylene resin and 66% by weight of silica powder. A capacitor separator made of a microporous film was obtained.
（比較例２）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、無機粉体として最大粒子径１５μｍ、含水率３．５質量％のシリカ粉体１９０部、可塑剤としてパラフィン系オイル４２０部をレーディゲミキサで混合し、実施例１と同様にして、ポリエチレン樹脂３４質量％とシリカ粉体６６質量％で構成される厚さ４０μｍの微多孔質膜からなるコンデンサ用セパレータを得た。
(Comparative Example 2)
70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million as a polyolefin resin, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, a maximum particle diameter of 15 μm, and a water content of 3.5 mass as an inorganic powder 190 parts by weight of silica powder and 420 parts of paraffinic oil as a plasticizer were mixed by a Ladige mixer, and in the same manner as in Example 1, a 40 μm-thickness composed of 34% by weight of polyethylene resin and 66% by weight of silica powder. A capacitor separator made of a microporous film was obtained.
（比較例３）
ポリオレフィン系樹脂として重量平均分子量２００万の高密度ポリエチレン樹脂粉体７０部と、重量平均分子量２０万の高密度ポリエチレン樹脂粉体３０部、無機粉体として最大粒子径１５μｍ、含水率６．１質量％のシリカ粉体１９０部、可塑剤としてパラフィン系オイル４２０部をレーディゲミキサで混合し、実施例１と同様にして、ポリエチレン樹脂３４質量％とシリカ粉体６６質量％で構成される厚さ４０μｍの微多孔質膜からなるコンデンサ用セパレータを得た。
(Comparative Example 3)
70 parts of a high density polyethylene resin powder having a weight average molecular weight of 2 million as a polyolefin resin, 30 parts of a high density polyethylene resin powder having a weight average molecular weight of 200,000, a maximum particle diameter of 15 μm, and a moisture content of 6.1 mass as an inorganic powder 190 parts by weight of silica powder and 420 parts of paraffinic oil as a plasticizer were mixed by a Ladige mixer, and in the same manner as in Example 1, a 40 μm-thickness composed of 34% by weight of polyethylene resin and 66% by weight of silica powder. A capacitor separator made of a microporous film was obtained.
次に、上記実施例１〜５、比較例１〜３にて得られた各セパレータについて、以下の方法により、各種特性評価を行った。結果を表１に示す。
［無機粉体の最大粒子径，平均粒子径］
レーザー式粒度分布測定器ＬＡ−５００（堀場製作所製）により測定した。
［無機粉体の含水率］
無機粉体１ｇを１０５℃で４時間乾燥させた時の水分含有率（質量％）を測定し、含水率とした。
［空隙率］
セパレータの見掛け密度と構成材料の固形分真密度から次式により計算した。
空隙率＝１００−（セパレータの見掛け密度／材料固形分真密度）×１００
［欠点数］
セパレータを０．１ｍｍの欠点（ピンホール、異物等）を検出する検出器に通し、検出器で検出された欠点を目視で確認し、１００ｍ2あたりの欠点の個数を測定し、欠点数とした。尚、欠点数の測定においては、検出器で検出された欠点のうち、無機粉体の粒子に起因する欠点のみをカウントし、他の異物や黒点等の欠点については除外した。
Next, various characteristics evaluation was performed by the following method about each separator obtained in the said Examples 1-5 and Comparative Examples 1-3. The results are shown in Table 1.
[Maximum particle size and average particle size of inorganic powder]
It was measured with a laser type particle size distribution analyzer LA-500 (manufactured by Horiba Seisakusho).
[Moisture content of inorganic powder]
The moisture content (mass%) when 1 g of inorganic powder was dried at 105 ° C. for 4 hours was measured and used as the moisture content.
[Porosity]
It calculated from the following formula from the apparent density of the separator and the solid density of the constituent material.
Porosity = 100− (separator apparent density / material solids true density) × 100
[Number of defects]
The separator is passed through a detector for detecting 0.1 mm defects (pinholes, foreign matters, etc.), the defects detected by the detector are visually confirmed, and the number of defects per 100 m 2 is measured to determine the number of defects. . In the measurement of the number of defects, of the defects detected by the detector, only defects due to inorganic powder particles were counted, and defects such as other foreign matters and black spots were excluded.
表１に示す、本願発明の実施例１〜５の結果から明らかなように、無機質粉体の含水率が３質量％以下であり、前記無機質粉体の最大粒子径Ａと膜厚Ｔの関係Ａ／Ｔが０．５以下であると、押出成形後のシートを薄膜化処理（圧延処理および／または延伸処理）を行った場合であっても、ピンホール等の欠点数が５個／１００ｍ2以下と非常に少なく、製品歩留の良い安定した品質のコンデンサ用セパレータが得られることを確認できた。
さらに、実施例１〜４のコンデンサ用セパレータは、空隙率が７０％以上と高く、低（内部）抵抗であり、かつピンホール等の欠点数が少なくて信頼性が高く、小型化、高性能化が要求されている電気二重層キャパシタ用のセパレータ、特に、有機系電解液を用いる電気二重層キャパシタ用のセパレータとして適しているものを得られることが確認できた。尚、実施例５のように、添加する可塑剤の配合量が低くなると、空隙率は低減した。
これに対し、比較例１のように前記Ａ／Ｔが０．５を超えるような場合、押出成形後のシートに薄膜化処理を行って得られたコンデンサ用セパレータは、ピンホール等の欠点数が１２０個／１００ｍ2と非常に多かった。また、前記無機粉体の含水率が３質量％を超えていると、比較例２および３に示すように、得られたコンデンサ用セパレータの欠点数が７〜２０個／１００ｍ2と多くなっていた。前記欠点数は、無機粉体の含水率が高くなるほど、増加する傾向にあった。
As is apparent from the results of Examples 1 to 5 of the present invention shown in Table 1, the moisture content of the inorganic powder is 3% by mass or less, and the relationship between the maximum particle diameter A and the film thickness T of the inorganic powder. When A / T is 0.5 or less, the number of defects such as pinholes is 5/100 m even when the extruded sheet is subjected to thinning treatment (rolling treatment and / or stretching treatment). 2 or less and very small, it was confirmed that good stable quality of the separator for capacitors product yield is obtained.
Further, the capacitor separators of Examples 1 to 4 have a high porosity of 70% or more, a low (internal) resistance, a small number of defects such as pinholes, high reliability, miniaturization, and high performance. It has been confirmed that a separator suitable for an electric double layer capacitor that is required to be manufactured, particularly a separator for an electric double layer capacitor that uses an organic electrolyte, can be obtained. As in Example 5, the porosity decreased when the amount of the plasticizer to be added was low.
On the other hand, when the A / T exceeds 0.5 as in Comparative Example 1, the capacitor separator obtained by subjecting the sheet after extrusion molding to thin film processing has a number of defects such as pinholes. Was 120 / 100m 2 . Moreover, when the moisture content of the inorganic powder exceeds 3% by mass, as shown in Comparative Examples 2 and 3, the number of defects of the obtained capacitor separator is 7-20 / 100 m 2. It was. The number of defects tended to increase as the moisture content of the inorganic powder increased.
Claims (5)
5. The capacitor separator according to claim 3, wherein the capacitor separator is an electric double layer capacitor separator using an organic electrolyte.
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| JP2007065065A (en) * | 2005-08-29 | 2007-03-15 | Konica Minolta Opto Inc | Optical film and its manufacturing method |
| WO2007037309A1 (en) * | 2005-09-28 | 2007-04-05 | Nippon Sheet Glass Company, Limited | Separator for energy-storage device and energy-storage device |
| JP2014179519A (en) * | 2013-03-15 | 2014-09-25 | Nippon Sheet Glass Co Ltd | Separator for electricity storage device, and electricity storage device |
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| JP2014179519A (en) * | 2013-03-15 | 2014-09-25 | Nippon Sheet Glass Co Ltd | Separator for electricity storage device, and electricity storage device |
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