JP4134628B2 - Laminated body and method for producing the same - Google Patents

Description

【００７９】
表１における単量体は、それぞれ以下の単量体である。
ＭＭＡ：メタアクリル酸メチル
２ＥＨＡ：アクリル酸２−エチルヘキシル
２ＥＨＭＡ：メタアクリル酸２−エチルヘキシル
ＥＡ：アクリル酸エチル
ＢＡ：アクリル酸ブチル
ＨＥＡ：アクリル酸２−ヒドロキシエチル（水酸基含有単量体）
ＨＥＭＡ：メタアクリル酸２−ヒドロキシエチル（水酸基含有単量体）
ＨＰＭＡ：メタアクリル酸２−ヒドロキシプロピル（水酸基含有単量体）
ＭＡＡ：メタクリル酸（カルボキシル基含有単量体）
ＡＡ：アクリル酸（カルボキシル基含有単量体）。
【００８０】
脱イオン水５００部を反応槽に入れて、液温度を７０℃に上昇させた。次に、(1) 表１に示す単量体組成の混合物３００部、(2)過硫酸アンモニウム３部を脱イオン水９７部に溶解した液１００部、並びに(3)酸性亜硫酸ナトリウム４部及び反応性乳化剤５部（商品名：アデカリアソープＳＥ−１０Ｎ、旭電化（株）製）を脱イオン水９１部に溶解した液１００部を、同時並行的に２時間で終了するように、攪拌しながら反応槽に滴下した。次いで引き続き７０℃にて２時間攪拌しながら重合反応を行い、本発明の要件を満たす水系エマルジョンＮｏ．Ａ〜Ｄを合成した。
【００８１】
また比較のために、本発明の要件を外れる水系エマルジョンＮｏ．Ｘ〜Ｚを合成した。
【００８２】
これら水系エマルジョンＮｏ．Ａ〜Ｄ及びＸ〜Ｚの中に含まれる樹脂の固形分濃度は、いずれも３０％前後であった。
【００８３】
参考例２（水系エマルジョン処理液の調製）
表１に示した水系エマルジョンにエッチング剤［５５％フッ化水素酸（工業用、ステラケミファー社製）又は６５％硝酸（工業用、日産化学（株）製）］を、得られる水系エマルジョンのｐＨ値が下記表２に示すｐＨ値になるように混合し、水系エマルジョン処理液Ｉ〜ＸIIを調製した。
【００８４】
【表２】

【００８５】
実施例１
（１）アルミニウム箔の調製
軟質アルミニウム箔（厚さ４０μｍ、住軽アルミ箔（株）製、商品名：べスパ８０２１）を、予め５０℃の１０％水酸化ナトリウム溶液に３０秒間浸漬し、次いで水洗し、更に脱イオン水で洗浄し、温風乾燥することにより、脱脂処理を施した軟質アルミニウム箔を得た。
【００８６】
（２）アルミニウム箔面上への樹脂膜層の形成
脱脂処理済軟質アルミニウム箔の両面に表２に示す水系エマルジョン処理液Iをロールコーターで塗布し、３００℃の熱風乾燥機で２０秒加熱乾燥して表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させた。
【００８７】
膜厚の測定：
樹脂膜層の膜厚は、水系エマルジョン処理液塗工前後のアルミニウム箔の重量変化から算出した。
【００８８】
（３）外層の形成
一方の樹脂膜層上に、ウレタン系ドライラミネート接着剤（東洋モートン（株）製、商品名：ＡＤ１２２／ＣＡＴ１０）を乾燥後に３ｇ／ｍ²となるように塗布して接着剤層を形成すると共に、該接着剤層と２５μｍの二軸延伸ナイロンフィルム（出光石油化学（株）製、商品名：Ｇ−１００）のコロナ放電処理面とを貼り合わせて、樹脂膜層上に外層を形成させた。
【００８９】
（４）内層の形成
他の一方の樹脂膜層上に、ウレタン系ドライラミネート接着剤（東洋モートン（株）製、商品名：ＡＤ−５０３／ＣＡＴ１０）を乾燥後に３ｇ／ｍ²となるように塗布して接着剤層を形成すると共に、該接着剤層と３０μｍの無延伸ポリプロピレンフィルム（二村化学工業（株）製、商品名：ＦＣＺＫ）のコロナ放電処理面とを貼り合わせて、本発明の電池外装用積層体を製造した。
【００９０】
実施例２
アルミニウム箔の調製、アルミニウム箔面上への樹脂膜層の形成及び外層の形成は、実施例１と同様に行った。次に内層の形成を以下のようにして行った。
【００９１】
即ち、他の一方の樹脂膜層上に、Ｔダイ押出機を用いて無水マレイン酸変性ポリプロピレンを１５μｍ厚さで押し出し、３０μｍの無延伸ポリプロピレンフィルム（二村化学工業（株）製、商品名：ＦＣＺＫ）をサンドラミネーションして、本発明の電池外装用積層体を製造した。
【００９２】
実施例３
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液IIを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、本発明の電池外装用積層体を製造した。
【００９３】
実施例４
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液IIIを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、本発明の電池外装用積層体を製造した。
【００９４】
実施例５
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液IVを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、本発明の電池外装用積層体を製造した。
【００９５】
実施例６
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液Ｖを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、本発明の電池外装用積層体を製造した。
【００９６】
実施例７
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液VIを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、本発明の電池外装用積層体を製造した。
【００９７】
実施例８
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液VIIを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、本発明の電池外装用積層体を製造した。
【００９８】
実施例９
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液VIIIを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、本発明の電池外装用積層体を製造した。
【００９９】
実施例１０
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液IXを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、本発明の電池外装用積層体を製造した。
【０１００】
比較例１
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液Ｘを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、電池外装用積層体を製造した。
【０１０１】
比較例２
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液XIを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、電池外装用積層体を製造した。
【０１０２】
比較例３
水系エマルジョン処理液Ｉの代わりに水系エマルジョン処理液XIIを用い、３００℃の熱風乾燥機で２０秒加熱乾燥した時の膜厚が表２に示す膜厚（片面の膜厚を示す）になるように、アルミニウム箔の両面に樹脂膜層を形成させる以外は、実施例２と同様にして、電池外装用積層体を製造した。
【０１０３】
上記で作成した電池外装用積層体について、８５℃の電解液（６フッ化リン酸リチウムをエチレンカーボネートに溶解し、１モルの６フッ化リン酸リチウム溶液としたもの）に浸漬し、アルミニウム箔と無水マレイン酸変性ポリプロピレン又は無延伸ポリプロピレンフィルムとの接着強度を浸漬から３日後、５日後、７日後、１０日後及び１４日後に評価して、その結果を表３にまとめて示した。
【０１０４】
評価基準としては、アルミニウム箔と無水マレイン酸変性ポリプロピレン又は無延伸ポリプロピレンフィルムとが剥離できないものを良好とし◎印で示し、剥離可能であるがデラミしていないものを普通とし○印で示し、デラミしているものを不良として×印で示した。
【０１０５】
【表３】

【０１０６】
表３からも明らかなように、本発明の電池外装用積層体は、経時的なアルミニウム箔と無水マレイン酸変性ポリプロピレン又は無延伸ポリプロピレンフィルムとの間のデラミがなく、電解液に対する耐性に優れたものであった。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a laminate suitable for packaging, in particular, a secondary battery such as lithium ion, and a method for producing the same.
[0002]
[Prior art]
Conventionally, as a variety of packaging bodies or packaging containers with hermetically sealed contents and a barrier property, a laminate in which a plastic film is the main component, an aluminum foil is provided in the intermediate layer, and a heat sealable layer that can be thermally bonded to the innermost layer is laminated. Is used.
[0003]
However, if the contents contain acid, alkali, organic solvent, etc., these components invade the adhesive interface between the heat seal layer and the aluminum foil through the heat seal layer, and over time the heat seal layer and the aluminum foil Is peeled off, and it is inevitable that the contents leak from the package or the packaging container.
[0004]
Therefore, in particular, when storing products containing strong acids, strong alkalis, etc. in the contents and products containing acids, alkalis, organic solvents, etc. in the contents over a long period of time, the laminate is used as a package or packaging container. I can not use it. Therefore, at present, metal cans are mainly used as packaging bodies or packaging containers for contents containing chemicals such as toluene, automotive compounds containing solvents, and the like.
[0005]
Recently, lithium ion secondary batteries are widely used in expensive products such as electronic devices and electronic parts, especially mobile phones, notebook computers, video cameras, satellites, and electric vehicles because of their high volumetric efficiency and weight efficiency. ing.
[0006]
In particular, since lithium ion polymer secondary batteries use a gel electrolyte such as a conductive polymer as an electrolyte, the lithium ion polymer secondary battery has an electrolyte solution compared to a lithium ion battery using a non-aqueous electrolyte. Since the risk of liquid leakage is small and the safety is excellent, it is possible to reduce the size and weight.
[0007]
A metal can that is formed by pressing a metal plate, metal foil, etc. into a cylindrical shape or a rectangular parallelepiped shape is generally used for the exterior of a lithium ion polymer secondary battery from the viewpoint of productivity, quality stability, etc. It is used for.
[0008]
However, when a metal can is used for the exterior of the secondary battery, there are many restrictions on the shape and design of the battery itself, as well as in electronic devices and electronic components in which a battery made of a metal can is mounted. There are also restrictions on the shape and design of the battery housing, and as a result, there is a problem that the shape of the electronic device and the electronic component itself cannot be a desired shape, and the electronic device and the electronic component are further reduced in size and weight. It has become an obstacle to conversion.
[0009]
Therefore, the exterior of the electronic device and the electronic component itself can be formed into a desired shape, and can be easily processed into a shape that matches the shape of the electronic device and the electronic component in order to further reduce the size and weight. Development is demanded. Also, as a metal used for the exterior, aluminum foil has attracted attention.
[0010]
Battery laminates used for the exterior of lithium ion polymer secondary batteries are required to have the following properties.
[0011]
(1) When water vapor gas enters the exterior of the secondary battery from the outside, the electrolyte is hydrolyzed to generate hydrofluoric acid, which corrodes the aluminum foil. In order to avoid this inconvenience, the main part of the secondary battery main body and a part of the electrode must have gas barrier properties capable of shutting off from outside air (especially water vapor gas).
[0012]
(2) The innermost layer of the exterior has excellent adhesion to the metal electrode constituting the secondary battery. Furthermore, the outermost inner layer of the exterior has excellent thermal adhesiveness.
[0013]
(3) The secondary battery is required to have a property (heat resistance and cold resistance) that can withstand the temperature environment in which it is used, specifically in a car in summer and in a cold region in winter. Furthermore, the temperature inside the secondary battery further increases due to charging / discharging when the secondary battery is used. Even when a secondary battery is used in such a harsh environment, the exterior must have stable performance such as thermal adhesion and gas barrier properties.
[0014]
(4) The gel adhesion (gel electrolyte) used in the secondary battery does not reduce the interlayer adhesion strength of the exterior.
[0015]
(5) Corrosion resistance to hydrofluoric acid generated by degradation, hydrolysis, etc. of the gel electrolyte used in the secondary battery.
[0016]
(6) It must be easy to form and have excellent productivity, such as having drawability.
[0017]
In order to satisfy these conditions, a battery exterior laminate that is excellent in workability and corrosion resistance and subjected to chromate treatment using hexavalent chromium or trivalent chromium in the surface treatment of the aluminum foil surface. Development has progressed. However, with the recent close-up of global environmental conservation issues, the use of harmful substances on humans has been restricted worldwide, and the review of treatment methods using chromium has been called out. . And development of the laminated body for battery exteriors which does not depend on chromate processing is desired.
[0018]
[Problems to be solved by the invention]
It is an object of the present invention to provide a package or a packaging container in which a heat-seal layer and an aluminum foil are not peeled off from contents containing acid, alkali, organic solvent, etc., and the contents are not leaked. It is to provide a suitable laminate.
[0019]
An object of the present invention is to provide a laminated body for an exterior of a lithium ion polymer secondary battery that is inferior in terms of corrosion resistance by conventional chromate treatment and has excellent gas barrier properties.
[0020]
An object of the present invention is to provide a laminate for an exterior of a lithium ion polymer secondary battery in which the interlayer adhesion strength of the exterior is not substantially reduced by the gel electrolyte (gel electrolyte) used in the secondary battery. That is.
[0021]
An object of the present invention is to provide a laminate for an exterior of a lithium ion polymer secondary battery having performance such as stable thermal adhesiveness and gas barrier property as an exterior even when the secondary battery is used in a severe environment. That is.
[0022]
[Means for Solving the Problems]
As a result of intensive studies to solve the above-mentioned problems, the present inventor intervenes a specific resin film layer between the aluminum foil and the inner layer in the laminated body for battery exterior in which the outer layer, the aluminum foil and the inner layer are laminated. As a result, it was found that a desired laminate for battery exterior was obtained. The present invention has been completed based on such findings.
1. The present invention is such that in a laminate in which an outer layer, an aluminum foil, and an inner layer are sequentially laminated, a resin film layer made of a resin having a hydroxyl group and a carboxyl group in the molecule is interposed between at least the aluminum foil and the inner layer. This is a featured laminate.
2. The present invention is the laminate described in 1 above, wherein the resin having a hydroxyl group and a carboxyl group in the molecule is a copolymer obtained using a monomer having a hydroxyl group and a monomer having a carboxyl group.
3. This invention is a laminated body of said 1 or 2 whose film thickness of a resin film layer is 0.3-3 micrometers.
4). This invention is a laminated body of said 1 whose innermost layer of an inner layer consists of olefin type heat-adhesive resin, and the thickness is 10-100 micrometers.
5. The present invention is the laminate according to 1 above, wherein the aluminum foil is a soft aluminum foil having a thickness of 15 to 100 μm.
6). In the present invention, an aqueous emulsion containing a resin having a hydroxyl group and a carboxyl group in the molecule is applied on an aluminum foil and dried to form a resin film layer on the aluminum foil, and then the outer layer and the inner layer are laminated. It is the manufacturing method of the laminated body characterized by these.
7. This invention is a manufacturing method of the laminated body of said 6 using the water-system emulsion which further mix | blended the etching agent for aluminum.
8). The present invention is a battery package obtained by thermally bonding the inner layers of the laminate so that the electrolyte can be sealed inside using the laminate according to any one of 1 to 4 above. .
9. The present invention is the battery package according to 8 above, wherein the battery is a lithium ion polymer secondary battery.
10. The present invention contains a resin having a hydroxyl group and a carboxyl group in the molecule, and contains an inorganic substance other than water, an inorganic acid, a polymerization initiator, a chain transfer agent, an emulsifier and a decomposition product thereof used in the production of the resin. It is a surface treating agent for aluminum which consists of a water-based emulsion which does not contain substantially.
11. The present invention is the surface treatment agent according to the above 10, wherein the resin having a hydroxyl group and a carboxyl group in the molecule is a copolymer obtained using a monomer having a hydroxyl group and a monomer having a carboxyl group. .
[0023]
DETAILED DESCRIPTION OF THE INVENTION
The laminate of the present invention is a laminate in which an outer layer, an aluminum foil, and an inner layer are sequentially laminated, and a resin film layer made of a resin having a hydroxyl group and a carboxyl group in the molecule is at least between the aluminum foil and the inner layer. It is provided.
[0024]
The laminate of the present invention can be particularly suitably used as a laminate for battery exterior, but its application is not limited to battery exterior. The contents to be packaged in the laminate of the present invention include liquid substances whose contents contain acid, alkali, organic solvent, etc., such as putty (thickening putty, thinning putty etc.), paint (oil-based paint etc.) ), Solvent-based compounds such as lacquer (clear lacquer, etc.), automotive compounds, and strong acid-based compounds such as Super Orange, Orange Power, etc. (both are trade names and planted wood). The laminate of the present invention can be used as a package or packaging container for these contents.
[0025]
Aluminum foil
The aluminum foil acts as a gas barrier layer for preventing gas such as water vapor gas and oxygen gas from entering the battery from the outside.
[0026]
The thickness of the aluminum foil is not particularly limited, but is usually from 15 to 100 μm, preferably from 20 to 80 μm in view of ensuring gas barrier properties, processing suitability during processing, and the like.
[0027]
When the thickness of the aluminum foil is significantly thinner than 15 μm, it is unavoidable that pinholes are generated in the aluminum foil alone, and there is a possibility that the gas barrier property is lowered. On the contrary, even if the thickness of the aluminum foil is extremely thicker than 100 μm, further improvement in gas barrier properties cannot be expected, and conversely, in order to reduce volume and weight energy density, it is desirable from the viewpoint of cost effectiveness. Absent.
[0028]
The aluminum foil is preferably a soft aluminum foil.
[0029]
Resin film layer
The resin film layer firmly bonds the aluminum foil and the inner layer, and the surface on the inner layer side of the aluminum foil includes, for example, gel electrolyte contained in the battery, hydrofluoric acid generated by degradation or hydrolysis of the gel electrolyte, etc. Provided to protect against.
[0030]
In the present invention, it is essential to use a resin having a hydroxyl group and a carboxyl group in the molecule as the resin constituting the resin film layer.
[0031]
Known resins can be widely used as the resin having a hydroxyl group and a carboxyl group in the molecule. Examples of such a resin include a copolymer obtained using a monomer having a hydroxyl group and a monomer having a carboxyl group.
[0032]
Examples of the copolymer obtained using a monomer having a hydroxyl group and a monomer having a carboxyl group include, for example, a copolymer of a monomer having a hydroxyl group and a monomer having a carboxyl group, and a hydroxyl group. Examples thereof include a monomer, a monomer having a carboxyl group, and a copolymer of a monomer copolymerizable with these monomers.
[0033]
The amount of hydroxyl group contained in the resin having a hydroxyl group and a carboxyl group in the molecule is usually about 0.2 to 2.5 mmol / g, preferably about 0.3 to 2 mmol / g. It is about 0.3 to 3.5 mmol / g, preferably about 0.5 to 3 mmol / g.
[0034]
As the monomer having a hydroxyl group, known ones can be widely used. For example, acrylic acid such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 3-hydroxypropyl acrylate, 4-hydroxybutyl acrylate, etc. Hydroxy-substituted C_2-4Hydroxy-substituted C of methacrylic acid such as alkyl ester, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl methacrylate, 4-hydroxybutyl methacrylate_2-4Examples include alkyl esters. These monomers having a hydroxyl group are used singly or in combination of two or more.
[0035]
A wide variety of known monomers can be used as the monomer having a carboxyl group. There may be one carboxyl group or two or more carboxyl groups.
[0036]
Examples of the monomer having one carboxyl group include acrylic acid and methacrylic acid.
[0037]
Examples of the monomer having two carboxyl groups include crotonic acid, itaconic acid, maleic acid, and fumaric acid.
[0038]
These monomers having a carboxyl group are used singly or in combination of two or more.
[0039]
Furthermore, a resin having a hydroxyl group and a carboxyl group in the molecule can be produced by using glycidyl methacrylate that generates a hydroxyl group and a carboxyl group by a ring-opening reaction.
[0040]
In the present invention, examples of the monomer copolymerizable with the hydroxyl group-containing monomer and the carboxyl group-containing monomer include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, and acrylic. Acrylic acid C such as n-butyl acid, isobutyl acrylate, 2-ethylhexyl acrylate_2-18Methacrylic acid C such as alkyl ester, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate_2-18Examples include alkyl esters. These monomers are used individually by 1 type or in mixture of 2 or more types.
[0041]
The thickness of the resin film layer is not limited, but is usually about 0.3 to 3 μm, preferably about 0.5 to 1.5 μm from the viewpoint of maintaining the adhesive strength with the aluminum foil. If the thickness of the resin film layer is less than 0.3 μm, the adhesive strength with the aluminum foil tends to decrease in a short time when it is attacked by the electrolyte or the like, which is not preferable. On the other hand, if the thickness of the resin film layer exceeds 3 μm, the moldability of the laminate is lowered, and the adhesive strength with the inner layer tends to be reduced due to cohesive failure of the resin film layer itself, which is not preferable.
[0042]
Formation of resin film layer
In forming the resin film layer, known methods can be widely adopted. In the present invention, instead of the chromate treatment currently widely used, for example, a method of applying a surface treatment agent shown below to an aluminum foil and drying to form a resin film on the aluminum foil is simple, It is preferable from an industrial viewpoint.
[0043]
The surface treatment agent is composed of an aqueous emulsion containing a resin having a hydroxyl group and a carboxyl group in the molecule.
[0044]
The concentration of the hydroxyl group- and carboxyl group-containing resin in the aqueous emulsion is usually about 5 to 50% by weight, preferably about 10 to 35% by weight.
[0045]
Aluminum foil has a defect that an oxide film is formed on the surface thereof and the adhesive strength with the resin film layer is lowered. Therefore, when forming the resin film layer on the aluminum foil by the above method, it is preferable to mix an aluminum foil etching agent in the aqueous emulsion to be used. A well-known thing can be widely used as an etching agent, For example, inorganic acids, such as hydrofluoric acid, nitric acid, a sulfuric acid, phosphoric acid, etc. are mentioned. When the etching agent is blended, the etching agent is blended so that the pH of the aqueous emulsion is within the range of about 1 to 3.5, preferably about 1.5 to 3.
[0046]
Resins having a hydroxyl group and a carboxyl group in the molecule can be synthesized by emulsion polymerization of a monomer having a hydroxyl group and a monomer having a carboxyl group. In the present invention, an aqueous emulsion obtained by such emulsion polymerization can be used as a surface treating agent for aluminum foil.
[0047]
Therefore, the water-based emulsion further contains a resin having a hydroxyl group and a carboxyl group in the molecule and water, as well as a polymerization initiator, a chain transfer agent, an emulsifier or a decomposition product thereof used for the synthesis of the resin as necessary. And may contain an etching agent.
[0048]
Among the surface treatment agents (aqueous emulsions) used in the present invention, surface treatment agents that do not contain inorganic substances such as Mn, Mg, and Si are preferable. When the surface of aluminum is treated using such a surface treatment agent and other materials are laminated on the treated surface, compared to using a surface treatment agent containing an inorganic substance such as Mn, Mg, Si, Aluminum and the material can be firmly adhered to each other, and peeling between the aluminum and the material can be significantly suppressed.
[0049]
The preferred surface treatment agent of the present invention contains a polymerization initiator, a chain transfer agent, an emulsifier or a decomposition product thereof in addition to a resin having a hydroxyl group and a carboxyl group in the molecule and water, and an etching agent as necessary. In addition, it does not substantially contain inorganic substances such as Mn, Mg, and Si blended in the conventional surface treatment agent.
[0050]
The resin film layer is formed by applying the aqueous emulsion on the surface of the aluminum foil according to a known application method such as a dipping method, a bar coating method, a roll coating method, a spin coating method, or a spraying method, and then drying.
[0051]
Drying is not particularly limited as long as it is a means capable of evaporating water in the water-based emulsion and forming a resin film. Therefore, the drying may be natural drying, but is usually performed by heating from an industrial viewpoint.
[0052]
As the energy source for heat drying, known materials can be widely used, and examples thereof include gas, electricity, infrared rays, and high frequency (induction heating).
[0053]
The heat drying temperature is, for example, suitably in the range of 60 ° C to 350 ° C, more preferably 80 ° C to 300 ° C. The time required for heating and drying may be arbitrarily set according to the heating and drying temperature, the coating amount of the aqueous emulsion to be applied, the line speed, and the like.
[0054]
Inner layer
The inner layer constituting the laminate of the present invention may be a single layer or a multilayer. It is preferable that the layer located on the most content side (for example, the electrolyte solution side) of the inner layer is a thermoadhesive resin layer.
[0055]
For example, since the layer located closest to the electrolyte side of the inner layer is a heat-adhesive resin layer, there are the following advantages. That is, when the battery exterior laminate is used as a battery, it can be securely held in a sealed system that is shut off from outside air (especially water vapor gas) by heat bonding. Moreover, even if it contacts with electrolyte solution over a long period of time, adhesive strength does not fall. Furthermore, it is possible to prevent the occurrence of problems such as electrolyte leakage and rupture in the battery high-temperature storage test (safety test).
[0056]
As the resin constituting the heat-adhesive resin layer, it is desirable to use a heat-adhesive resin having a melting point of 80 ° C. or higher in consideration of a high temperature storage test (safety test) of the battery. In view of availability and cost, an olefin-based heat adhesive resin is preferable.
[0057]
As the olefinic heat-adhesive resin, known resins can be widely used. For example, low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, ethylene-α-olefin copolymer, ethylene-acrylic acid. Copolymer, ethylene-methacrylic acid copolymer, ethylene-acrylic acid ester copolymer, ethylene-methacrylic acid ester copolymer, ethylene-vinyl acetate copolymer, ionomer, polypropylene, maleic acid modified polypropylene, ethylene-propylene A copolymer etc. can be mentioned.
[0058]
The inner layer may be composed of only the above-mentioned heat-adhesive resin layer, or a synthetic resin layer composed of a single layer or multiple layers may be provided between the heat-adhesive resin layer and the aluminum foil. .
[0059]
Examples of the resin constituting the synthetic resin layer include known polyester-based resins, polyamide-based resins, and fluorine-based resins in addition to the olefin-based heat-adhesive resins.
[0060]
This synthetic resin layer may be formed into a sheet by unstretched or uniaxially or biaxially stretching the resin constituting the synthetic resin layer, and then formed according to a known lamination method such as a dry lamination method or a sand lamination method. These resins may be formed by extrusion using an extruder. In addition, when the resin for forming the inner layer is formed into a sheet, an easy adhesion treatment such as a corona discharge treatment and / or an atmospheric pressure plasma treatment is performed on the required surface for the purpose of imparting wettability to the sheet surface. Can do.
[0061]
Specific examples of the structure of the inner layer include the following.
(1) A structure in which an inner layer is laminated by co-extrusion of acid-modified polypropylene / polypropylene on the surface on which an aluminum foil resin film layer is formed so that the acid-modified polypropylene is in contact with the resin film layer.
(2) A structure in which an acid-modified polypropylene solution is applied to the surface on which the resin film layer of the aluminum foil is formed and dried, and then an unstretched polypropylene film is laminated by heat lamination.
(3) A structure in which a surface on which an aluminum foil resin film layer is formed and an unstretched polypropylene film are extruded and laminated by sand lamination by extruding polypropylene resin.
(4) A structure in which an aluminum foil resin film layer surface and an unstretched polypropylene film subjected to corona discharge treatment are bonded and laminated with an adhesive for dry lamination.
[0062]
The above heat-adhesive resin layer constituting the inner layer needs to be hermetically sealed so that the electrodes provided in the battery do not have a gap, and the thickness is suitably 10 to 100 μm, and preferably 20 to 80 μm. . When the thickness is less than 10 μm, pinholes are likely to be generated between the electrode and the heat-adhesive resin layer at the time of heat-bonding, and there is a risk that the resistance to the electrolytic solution is lowered, which is not preferable. In addition, when the thickness of the heat-adhesive resin layer is greater than 100 μm, no significant improvement effect is observed in the pinhole generated between the electrode and the heat-adhesive resin layer generated during the heat-adhesion, and the volume and weight energy Since the density is lowered, it is not preferable from the viewpoint of cost effectiveness.
[0063]
Outer layer
The laminated body for battery exterior of the present invention can be used as a packaging material for secondary batteries in this state by providing a heat-adhesive resin layer on the inner layer, but compared with the one using a metal can as the exterior. It is desirable to improve resistance to external force, particularly puncture resistance. For this reason, it is preferable to provide an outer layer on the outside of the aluminum foil for the purpose of improving puncture resistance.
[0064]
The outer layer may be a single layer or a multilayer as in the case of the inner layer.In particular, in the case of a single layer, it is necessary to achieve the above-mentioned object by itself, and the mechanical strength is excellent. At least dimensional stability against heat during thermal bonding is required. Considering these, the resin constituting the outer layer is desirably a polyester film stretched in the biaxial direction, a polyamide film stretched in the biaxial direction, or the like. Examples of the biaxially stretched polyester film include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, and polycarbonate. Examples of the biaxially stretched polyamide film include nylon 6, nylon 66, and the like.
[0065]
When the laminate of the present invention is drawn, a biaxially stretched polyamide film having a larger elongation than the biaxially stretched polyester film is preferable.
[0066]
When the outer layer is formed of a single layer of a biaxially stretched polyester film or a biaxially stretched polyamide film, the thickness is preferably 6 μm or more. When the thickness is extremely thinner than 6 μm, the protective effect of the aluminum foil against external force is reduced, and particularly when drawing is performed, pinholes and breakage are likely to occur in the aluminum foil, and molding defects are likely to occur. Further, whether the outer layer is a single layer or a multilayer, if the thickness is thicker than 25 μm, no significant improvement effect is observed in terms of protection of the aluminum foil against external force, and the volume and weight energy density are reduced. It is not preferable from the viewpoint of cost effectiveness.
[0067]
The outer layer and the aluminum foil can be laminated by, for example, a well-known dry lamination method using a dry laminate adhesive. In addition, the biaxially stretched film used for the outer layer can be subjected to easy adhesion treatment such as corona discharge treatment and / or atmospheric pressure plasma treatment on a necessary surface for the purpose of imparting wettability to the film surface.
[0068]
In the present invention, the resin film layer can be further provided on the outer layer side surface of the aluminum foil as necessary, similarly to the inner layer side surface.
[0069]
【The invention's effect】
According to the present invention, even when the contents containing acid, alkali, organic solvent, etc. are contacted, the heat seal layer and the aluminum foil are not peeled off and the package or the packaging container in which the contents do not leak out. A laminate suitable for is provided.
[0070]
The laminate of the present invention is provided with a gas barrier property that can block the backbone of the secondary battery body and a part of the electrode from the outside air.
[0071]
In the laminate of the present invention, for example, when this is used as a battery exterior, the innermost layer of the exterior is excellent in adhesiveness with a metal electrode constituting the secondary battery. Moreover, the laminated body of this invention is excellent in the heat adhesiveness of innermost layers of an exterior.
[0072]
The laminate of the present invention has performances such as stable thermal adhesion and gas barrier properties as an exterior even under severe conditions.
[0073]
In the laminate of the present invention, the interlayer adhesive strength of the exterior is not substantially lowered by the gel electrolyte (gel electrolyte) used in the secondary battery.
[0074]
The laminate of the present invention has corrosion resistance against hydrofluoric acid generated by degradation, hydrolysis, etc. of the gel electrolyte used in the secondary battery.
[0075]
The laminate of the present invention has a drawability and is easy to form and has excellent productivity.
[0076]
【Example】
The present invention will be further clarified by the following examples. Hereinafter, “parts” simply means “parts by weight”, and “%” means “% by weight”.
[0077]
Reference Example 1 (Preparation of aqueous emulsion)
[0078]
[Table 1]

[0079]
The monomers in Table 1 are the following monomers, respectively.
MMA: Methyl methacrylate
2EHA: 2-ethylhexyl acrylate
2EHMA: 2-ethylhexyl methacrylate
EA: ethyl acrylate
BA: butyl acrylate
HEA: 2-hydroxyethyl acrylate (hydroxyl-containing monomer)
HEMA: 2-hydroxyethyl methacrylate (hydroxyl group-containing monomer)
HPMA: 2-hydroxypropyl methacrylate (hydroxyl group-containing monomer)
MAA: Methacrylic acid (carboxyl group-containing monomer)
AA: Acrylic acid (carboxyl group-containing monomer).
[0080]
500 parts of deionized water was placed in the reaction vessel and the liquid temperature was raised to 70 ° C. Next, (1) 300 parts of the monomer composition mixture shown in Table 1, (2) 100 parts of a solution of 3 parts of ammonium persulfate in 97 parts of deionized water, and (3) 4 parts of acidic sodium sulfite and the reaction 100 parts of a solution obtained by dissolving 5 parts of a natural emulsifier (trade name: Adekaria Soap SE-10N, manufactured by Asahi Denka Co., Ltd.) in 91 parts of deionized water is stirred so as to be completed in 2 hours simultaneously. The solution was added dropwise to the reaction vessel. Subsequently, the polymerization reaction was continued with stirring at 70 ° C. for 2 hours, and aqueous emulsion No. 1 satisfying the requirements of the present invention was obtained. A to D were synthesized.
[0081]
For comparison, an aqueous emulsion No. 1 deviating from the requirements of the present invention. X to Z were synthesized.
[0082]
These aqueous emulsion Nos. The solid content concentrations of the resins contained in A to D and X to Z were all around 30%.
[0083]
Reference Example 2 (Preparation of aqueous emulsion treatment liquid)
Etching agent [55% hydrofluoric acid (for industrial use, manufactured by Stella Chemipher) or 65% nitric acid (for industrial use, manufactured by Nissan Chemical Co., Ltd.)] in the aqueous emulsion shown in Table 1] The aqueous emulsion treatment liquids I to XII were prepared by mixing so that the pH value was as shown in Table 2 below.
[0084]
[Table 2]

[0085]
Example 1
(1) Preparation of aluminum foil
A soft aluminum foil (thickness 40 μm, manufactured by Sumi Light Aluminum Foil Co., Ltd., trade name: Vespa 8021) was previously immersed in a 10% sodium hydroxide solution at 50 ° C. for 30 seconds, then washed with water, and further deionized water. By washing with hot air and drying with warm air, a soft aluminum foil subjected to degreasing treatment was obtained.
[0086]
(2) Formation of resin film layer on aluminum foil surface
The water-based emulsion treatment liquid I shown in Table 2 is applied to both surfaces of the degreased soft aluminum foil with a roll coater, and heated and dried with a hot air dryer at 300 ° C. for 20 seconds. The resin film layer was formed on both surfaces of the aluminum foil.
[0087]
Measurement of film thickness:
The film thickness of the resin film layer was calculated from the change in weight of the aluminum foil before and after coating with the aqueous emulsion treatment liquid.
[0088]
(3) Formation of outer layer
On one resin film layer, urethane-based dry laminate adhesive (manufactured by Toyo Morton Co., Ltd., trade name: AD122 / CAT10) is dried and then 3 g / m.²The adhesive layer and the corona discharge treated surface of a 25 μm biaxially stretched nylon film (trade name: G-100, manufactured by Idemitsu Petrochemical Co., Ltd.) By bonding, an outer layer was formed on the resin film layer.
[0089]
(4) Formation of inner layer
3 g / m after drying a urethane-based dry laminate adhesive (manufactured by Toyo Morton Co., Ltd., trade name: AD-503 / CAT10) on the other resin film layer²The adhesive layer is applied to form the adhesive layer, and the corona discharge treated surface of the 30 μm unstretched polypropylene film (Fujimura Chemical Co., Ltd., trade name: FCZK) is bonded together. The laminated body for battery exterior of this invention was manufactured.
[0090]
Example 2
Preparation of the aluminum foil, formation of the resin film layer on the aluminum foil surface, and formation of the outer layer were carried out in the same manner as in Example 1. Next, the inner layer was formed as follows.
[0091]
That is, a maleic anhydride-modified polypropylene was extruded to a thickness of 15 μm using a T-die extruder on the other resin film layer, and a 30 μm unstretched polypropylene film (manufactured by Nimura Chemical Co., Ltd., trade name: FCZK). ) Was laminated to produce a laminate for battery exterior of the present invention.
[0092]
Example 3
Using the aqueous emulsion treatment liquid II instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried with a hot air dryer at 300 ° C. for 20 seconds becomes the film thickness shown in Table 2 (showing the film thickness on one side) In addition, a battery exterior laminate of the present invention was produced in the same manner as in Example 2 except that resin film layers were formed on both surfaces of the aluminum foil.
[0093]
Example 4
Using the aqueous emulsion treatment liquid III instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried with a hot air dryer at 300 ° C. for 20 seconds becomes the film thickness shown in Table 2 (showing the film thickness on one side) In addition, a battery exterior laminate of the present invention was produced in the same manner as in Example 2 except that resin film layers were formed on both surfaces of the aluminum foil.
[0094]
Example 5
Using the aqueous emulsion treatment liquid IV instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried with a hot air dryer at 300 ° C. for 20 seconds becomes the film thickness shown in Table 2 (showing the film thickness on one side) In addition, a battery exterior laminate of the present invention was produced in the same manner as in Example 2 except that resin film layers were formed on both surfaces of the aluminum foil.
[0095]
Example 6
Using the aqueous emulsion treatment liquid V instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried for 20 seconds with a hot air dryer at 300 ° C. becomes the film thickness shown in Table 2 (showing the film thickness on one side) In addition, a battery exterior laminate of the present invention was produced in the same manner as in Example 2 except that resin film layers were formed on both surfaces of the aluminum foil.
[0096]
Example 7
Using the aqueous emulsion treatment liquid VI instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried with a hot air dryer at 300 ° C. for 20 seconds becomes the film thickness shown in Table 2 (showing the film thickness on one side) In addition, a battery exterior laminate of the present invention was produced in the same manner as in Example 2 except that resin film layers were formed on both surfaces of the aluminum foil.
[0097]
Example 8
Using the aqueous emulsion treatment liquid VII instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried for 20 seconds with a hot air dryer at 300 ° C. becomes the film thickness shown in Table 2 (showing the film thickness on one side) In addition, a battery exterior laminate of the present invention was produced in the same manner as in Example 2 except that resin film layers were formed on both surfaces of the aluminum foil.
[0098]
Example 9
Using the aqueous emulsion treatment liquid VIII instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried with a hot air dryer at 300 ° C. for 20 seconds becomes the film thickness shown in Table 2 (showing the film thickness on one side) In addition, a battery exterior laminate of the present invention was produced in the same manner as in Example 2 except that resin film layers were formed on both surfaces of the aluminum foil.
[0099]
Example 10
Using the aqueous emulsion treatment liquid IX instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried with a hot air dryer at 300 ° C. for 20 seconds becomes the film thickness shown in Table 2 (showing the film thickness on one side) In addition, a battery exterior laminate of the present invention was produced in the same manner as in Example 2 except that resin film layers were formed on both surfaces of the aluminum foil.
[0100]
Comparative Example 1
Using the aqueous emulsion treatment liquid X instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried with a hot air dryer at 300 ° C. for 20 seconds becomes the film thickness shown in Table 2 (showing the film thickness on one side) A battery outer laminate was produced in the same manner as in Example 2 except that resin film layers were formed on both sides of the aluminum foil.
[0101]
Comparative Example 2
Using the aqueous emulsion treatment liquid XI instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried with a hot air dryer at 300 ° C. for 20 seconds becomes the film thickness shown in Table 2 (showing the film thickness on one side). A battery outer laminate was produced in the same manner as in Example 2 except that resin film layers were formed on both sides of the aluminum foil.
[0102]
Comparative Example 3
Using the aqueous emulsion treatment liquid XII instead of the aqueous emulsion treatment liquid I, the film thickness when heated and dried with a hot air dryer at 300 ° C. for 20 seconds becomes the film thickness shown in Table 2 (showing the film thickness on one side) A battery outer laminate was produced in the same manner as in Example 2 except that resin film layers were formed on both sides of the aluminum foil.
[0103]
The laminated body for battery exterior prepared above is immersed in an electrolytic solution at 85 ° C. (one obtained by dissolving lithium hexafluorophosphate in ethylene carbonate to give a 1 mol lithium hexafluorophosphate solution), and then an aluminum foil. The adhesive strength between the polypropylene and maleic anhydride-modified polypropylene or unstretched polypropylene film was evaluated 3 days, 5 days, 7 days, 10 days, and 14 days after immersion, and the results are summarized in Table 3.
[0104]
As evaluation criteria, aluminum foil and maleic anhydride-modified polypropylene or unstretched polypropylene film cannot be peeled. What is doing is shown by x mark as a defect.
[0105]
[Table 3]

[0106]
As apparent from Table 3, the laminate for battery exterior of the present invention has no delamination between the aluminum foil and the maleic anhydride-modified polypropylene or non-stretched polypropylene film over time, and has excellent resistance to the electrolyte. It was a thing.

Claims (9)

In a laminate in which an outer layer, an aluminum foil, and an inner layer are sequentially laminated, at least between the aluminum foil and the inner layer , a monomer having a hydroxyl group, a monomer having a carboxyl group, and copolymerization with these monomers are possible. A battery exterior laminate characterized by interposing a resin film layer made of a copolymer obtained using a monomer ,
The monomer having a hydroxyl group is at least one selected from the group consisting of hydroxy-substituted C _2-4 alkyl ester of acrylic acid and hydroxy-substituted C _2-4 alkyl ester of methacrylic acid ;
The monomer having a carboxyl group is at least one selected from the group consisting of acrylic acid and methacrylic acid;
Wherein is at least one monomer copolymerizable with monomer selected from the group consisting of acrylic acid C _2-18 alkyl esters and methacrylic acid C _2-18 alkyl ester,
Battery exterior laminate. The monomer having a hydroxyl group is 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate or 2-hydroxypropyl methacrylate;
The monomer having a carboxyl group is acrylic acid or methacrylic acid,
The monomer copolymerizable with monomers methyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, ethyl or butyl acrylate acrylate, laminate according to claim 1.   The laminate according to claim 1 or 2, wherein the resin film layer has a thickness of 0.3 to 3 µm.   The laminate according to claim 1, wherein the innermost layer of the inner layer is made of an olefin-based heat-adhesive resin and has a thickness of 10 to 100 μm.   The laminate according to claim 1, wherein the aluminum foil is a soft aluminum foil having a thickness of 15 to 100 μm. An aqueous emulsion containing a monomer having a hydroxyl group, a monomer having a carboxyl group, and a copolymer obtained by copolymerization with these monomers is applied onto an aluminum foil and dried. Then, after forming the resin film layer on the aluminum foil, a method for producing a laminated body for battery exterior in which an outer layer and an inner layer are laminated ,
The monomer having a hydroxyl group is at least one selected from the group consisting of hydroxy-substituted C _2-4 alkyl ester of acrylic acid and hydroxy-substituted C _2-4 alkyl ester of methacrylic acid ;
The monomer having a carboxyl group is at least one selected from the group consisting of acrylic acid and methacrylic acid;
Wherein is at least one monomer copolymerizable with monomer selected from the group consisting of acrylic acid C _2-18 alkyl esters and methacrylic acid C _2-18 alkyl ester,
A method for producing a laminate for battery exterior .   The manufacturing method of the laminated body of Claim 6 using the water-system emulsion which further mix | blended the etching agent for aluminum.   A battery package obtained by thermally bonding the inner layers of the laminate using the laminate according to any one of claims 1 to 4 so that the electrolyte can be sealed inside.   The battery packaging body according to claim 8, wherein the battery is a lithium ion polymer secondary battery.