JP2002110112A - Case material for lithium ion cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminate such that bond strength between the face of an aluminum film and the face of a sealant layer is not reduced, and that delamination is not caused by using a package comprising the laminate even when storing a strong permeable substance or the like as a content for a long time in the laminate composing of a base material film, the aluminum film and the sealant layer. SOLUTION: In the laminate such that an aluminum film 3, a bonding layer 4 and a sealant layer 5 are laminated in order on a base material film 1 of single-layer or multi-layer, a boehmite treatment is applied at least to the face by the side of the bonding layer 4 of the aluminum film 3, and the bonding layer 4 is comprised of an isocyanate compound at the same time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminate having a multilayer structure in which aluminum foil is laminated as a gas barrier material in the field of packaging of industrial products and the like. Even so, an object of the present invention is to provide a laminate in which the laminate strength between the aluminum foil layer and the sealant layer does not decrease without being affected by the highly permeable contents.

[0002]

2. Description of the Related Art Conventionally, in packaging materials such as pharmaceuticals and industrial products, aluminum foil is mainly used as a gas barrier material, and a laminate laminated with another base film or sealant film is used. The method of bonding the barrier material of these laminates and the sealant layer made of a resin film is mainly a dry lamination method using a polyurethane-based, polyethyleneimine-based or organic titanium-based adhesive or a melt extrusion lamination method. Was common.

[0003]

However, when a lithium ion battery is packaged in a package using these adhesives, a strongly permeable electrolyte containing LiPF ₆ passes through the sealant layer, and the barrier property is reduced. A dead end on the surface of a certain aluminum foil layer, the adhesive layer there swells, the lamination strength between the aluminum foil and the sealant layer decreases, and finally delamination occurs, causing problems such as leakage of the electrolyte. was there. Therefore, there is a demand for a packaging material which does not cause a decrease in the adhesive strength between the aluminum foil and the sealant layer even after the contents of these highly permeable substances are packaged and stored for a long period of time, and which does not cause delamination.

An object of the present invention is to provide a laminate comprising a base film, an aluminum foil, and a sealant layer, even when a strongly permeable material or the like is packaged as a content for a long period of time using a package comprising the laminate. Another object of the present invention is to provide a laminate in which the adhesive strength between an aluminum foil and a sealant layer does not decrease and delamination does not occur.

[0005]

According to the first aspect of the present invention, there is provided a laminate in which an aluminum foil, an adhesive layer, and a sealant layer are sequentially laminated on a single-layer or multi-layer substrate film. Wherein the surface on the side of the adhesive layer is subjected to boehmite treatment and the adhesive layer is made of an isocyanate compound.

A second aspect of the present invention provides a laminate in which an aluminum foil, an adhesive layer, and a sealant layer are sequentially laminated on a single-layer or multilayer base film, wherein both surfaces of the aluminum foil are subjected to boehmite treatment. And an outer layer for a lithium ion battery, wherein the adhesive layer is made of an isocyanate compound.

Next, a third aspect of the present invention is the invention according to the first or second aspect, wherein the resin film of the sealant layer is formed by a melt extrusion laminating method or a 190
An exterior material for a lithium-ion battery, wherein the exterior material is laminated on the boehmite-treated surface of the aluminum foil via the adhesive layer by any one of a thermocompression lamination method at a temperature of not less than ° C.

[0008]

According to the present invention, since the resin film of the sealant layer is laminated at a high temperature on the boehmite-treated surface of the aluminum foil via the adhesive layer made of the isocyanate compound, it is a highly permeable substance as the content. Even if the electrolytic solution or the like is packaged for a long time, there is no decrease in the adhesive strength between the aluminum foil and the sealant layer, and no delamination occurs.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION An exterior material for a lithium ion battery of the present invention will be described in detail below in accordance with embodiments.

The invention according to claims 1 and 2 of the present invention will be described in detail. FIG. 1 is a side sectional view showing an embodiment of the present invention. In the order of the thickness direction, the base film 1,
An adhesive layer 2, an aluminum foil 3, an adhesive layer 4, and a sealant layer 5 are formed.

The base film 1 may be a single-layer film such as a biaxially-stretched polypropylene film (OPP film), a biaxially-stretched polyester film (PET film), a biaxially-stretched nylon film (ONY film), or a multilayer film in which these films are laminated. Film is preferred. When a multilayer film is used, it is more preferable that the outermost surface be a PET film. As a lamination method, a polyurethane adhesive or the like is used, and a known dry lamination method or the like is used for lamination. The thickness of each film is 20 ~
40 μm, PET film of 6 to 25 μm, and ONY film of 15 to 25 μm can be used.

As the adhesive layer 2, a two-component curable urethane adhesive which is generally used as an adhesive for dry lamination is used, and the coating method is a gravure coating method or a roll coating method. I do. The application amount of the adhesive is 1 to 5 g / m ² (dry state).

The boehmite treatment applied to the aluminum foil 3 is performed by adding an additive such as ammonia or triethanolamine to distilled water in an amount of 0.01 to 1.0% by weight, preferably 0.1 to 0.5% by weight. Make a processing solution in the range,
The treatment liquid is in the range of 75 to 100 ° C, preferably 85 to 100 ° C.
Heating in the range of 100 ° C., more preferably in the range of 90 to 100 ° C., for one minute or more on one or both sides of the aluminum foil,
By treating for preferably 2 minutes or more, more preferably 3 minutes or more, an aluminum foil subjected to boehmite treatment can be obtained. This processing may be performed by a web system using a coater or the like, or may be performed by a batch system. In the laminate of the present invention, it is necessary that at least the surface of the aluminum foil 3 on the side of the adhesive layer 4 is subjected to boehmite treatment.

By performing the boehmite treatment, the surface of the aluminum foil has a needle-like structure, and a large amount of -OH groups can be present on the surface. By forming a bond or the like, the adhesion strength can be further increased.

As the aluminum foil 3, a general soft aluminum foil can be used.
A range of μm is available.

The isocyanate compound used for the adhesive layer 4 includes 2,4-tolylene diisocyanate,
Various diisocyanate monomers such as 2,6-tolylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate, and 4,4-diphenylmethane diisonate, and polymers and derivatives thereof are used.

The amount of the isocyanate compound to be applied is the same as that of a conventional two-part curable urethane adhesive or the like.
The two may react with each other to form a weak bond with solvents. Therefore, the thickness applied to the boehmite-treated surface of the aluminum foil is preferably 3 μm or less, more preferably 1 μm or less.

The -NCO group in the applied isocyanate compound and the -OH group generated during the high-temperature lamination of the resin film of the sealant layer 5 form a urethane bond,
By forming a network structure or the like, strong adhesion is obtained, and it has an effect of imparting resistance to various organic electrolytes and the like.

The method according to claim 3 of the present invention will be described in detail. As a method of laminating the resin film of the sealant layer 5, a single-layer or multi-layer base film 1 and a polyurethane adhesive 2 are used in advance. Then, a 5 to 10% by weight solution of the above isocyanate compound is used as an adhesive layer 4 on the boehmite-treated surface of the aluminum foil 3 bonded by a known method by a gravure coating method or the like to a thickness of 0.3 μm (dry state) or less. The film is thinly coated, dried, and then melt-extruded from a thermoplastic polyolefin-based resin or a copolymer resin thereof at a resin temperature of 200 to 350 ° C. on the coated surface to form a film and laminated by a melt extrusion lamination method. I do.

Alternatively, the adhesive layer 4 is applied to the boehmite-treated surface of the aluminum foil 3 which has been bonded in advance by a known method using a single-layer or multilayer base film 1 and a polyurethane-based adhesive by a dry laminating machine or the like. A 5 to 10% by weight solution of the above isocyanate compound is thinly applied by a gravure coating method or the like so as to have a thickness of 0.3 μm (dry state) or less, and is dried. A film formed from a polyolefin-based resin or a copolymer resin thereof is laminated, and the film is laminated by pressure bonding with a heating roll at a temperature of 190 ° C. or higher, followed by lamination by a thermal compression lamination method.
Lamination may be performed by any method.

The sealant layer 5 is laminated to form a package. For example, polyethylene, polypropylene, ethylene-vinyl acetate copolymer, ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer,
Thermoplastic resin consisting of one kind of ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, ethylene-methyl acrylate copolymer, ionomer resin, or a blend of two or more kinds, or from those resins It is formed by the method as described above using such films. The thickness is determined depending on the purpose, but is generally in the range of 30 to 110 μm.

[0022]

EXAMPLES Next, the packaging material for a lithium ion battery of the present invention will be described below with reference to specific examples. The present invention is not limited to these examples.

Example 1 A 25 μm-thick biaxially stretched nylon film used as a base film 1 was coated with a polyurethane-based adhesive at a rate of 4 g / m ² by a gravure method using a dry laminator on one side (dry state). ) After coating and drying, use a separate coater machine to
The foil is subjected to a surface treatment for 3 minutes with hot water containing 95% by weight containing 95% by weight, and a boehmite-treated aluminum foil 3 having a thickness of 40 μm is bonded by a known method. Then, the aluminum foil 3
Of a tolylene diisocyanate (CAT-10, Toyo Morton Co., Ltd.) solution having a solid content of 5% by weight as the adhesive layer 4 on the boehmite-treated surface of the adhesive layer 4 by a gravure method so as to have a thickness of 3 μm (dry state) It was applied and dried, and a 30 μm-thick polyethylene film previously formed as a sealant layer 5 was laminated on the applied surface, and the temperature was 200 μm.
The package was pressure-bonded with a heating roll at ℃ and laminated to prepare an exterior material for a lithium ion battery of the present invention.

<Example 2> In Example 1, a polyethylene resin (trade name: Novatec, LY20) manufactured by Nippon Polychem Co., Ltd. was used as the sealant layer 5 with an extruder at a resin temperature of 320 ° C and a thickness of 30 µm. An exterior material for a lithium-ion battery of the present invention was prepared in the same manner except that melt extrusion film formation and lamination were performed as described above.

Comparative Example 1 A 25 μm thick biaxially stretched nylon film used as the base film 1 was coated with a polyurethane adhesive at a rate of 4 g / m ² (dry) by a gravure method using a dry laminating machine. State) Coated and dried, and a 40 μm-thick aluminum foil which has not been subjected to boehmite treatment as an aluminum foil 3 is bonded to the coated surface, and then the same polyurethane-based adhesive is applied at 4 g / m ² (
(Dry state) Coating and drying, sealant layer 5 on the coating surface
Then, a polyethylene film having a thickness of 30 μm, which had been formed in advance, was laminated, pressure-bonded with a conventional heating roll at 50 ° C., and laminated to prepare an exterior material for a lithium ion battery for comparison.

<Test Method> Ethyl carbonate / ethyl methyl carbonate = 1/1 + LiPF ₆ (1.5N)
Of the packaging materials of Examples 1 and 2 and Comparative Example 1 in the electrolytic solution of
It was cut into a size of 30 mm × 30 mm, immersed and stored at 85 ° C. for 3 days, 1 week and 2 weeks, and the laminate strength between the aluminum foil of the exterior material and the sealant layer and the appearance were evaluated.

<Evaluation> Using the packaging materials for lithium ion batteries prepared in Examples 1 and 2 and Comparative Example 1, the electrolyte resistance of the packaging materials was evaluated. Table 1 shows the results.

[0028]

[Table 1]

From the results shown in Table 1, in Examples 1 and 2, even after a storage period of 2 weeks, the aluminum foil and the film of the sealant layer are firmly adhered so that they cannot be peeled off, and delamination naturally occurs. Absent. On the other hand, in Comparative Example 1, the aluminum foil and the film of the sealant layer were completely peeled off after a storage period of 3 days, and delamination occurred.

[0030]

According to the present invention, the exterior material for a lithium ion battery according to the present invention is obtained by applying a boehmite treatment to the surface of the aluminum foil in the laminate on the adhesive layer side, and applying a sealant layer to the treated surface via an adhesive layer made of an isocyanate compound. Is laminated at a high temperature, so that even if it is stored for a long time after packaging a highly permeable organic electrolyte as the content, there is no decrease in the adhesive strength between the aluminum foil and the sealant layer, and delamination is also possible. Does not occur. Therefore, the exterior material for a lithium ion battery of the present invention has sufficient resistance as a laminate for packaging them, and other industrial products containing a highly permeable substance as a content (for example, a disinfectant, a dispersant). It can also be used as a packaging material.

[Brief description of the drawings]

FIG. 1 is a side sectional view of an exterior material for a lithium ion battery of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Base film 2 ... Adhesive layer 3 ... Aluminum foil 4 ... Adhesive layer 5 ... Sealant layer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) B65D 65/40 B65D 65/40 D 5H011 C23C 22/66 C23C 22/66 // B29K 105: 20 B29K 105: 20 105: 22 105: 22 B29L 9:00 B29L 9:00 F term (reference) 3E086 AB01 BA02 BA04 BA13 BA15 BA24 BB74 BB77 CA40 4F100 AB10B AB33B AK01D AK04 AK46 AK51C AK51G AT00A BA04 BA10A BA10D CB00C EHEJB38 EJ00D GB15 GB41 JK06 JL11C JL12D 4F207 AA42 AD03 AD05 AD20 AD33 AD34 AG03 AH33 KA01 KB13 KJ05 KJ09 KK84 KK85 4F211 AA42 AD03 AD05 AD20 AD33 AD34 AG03 AH33 AR06 TA03 TC02 TD11 TH02 TH06 TH22 TN47 TQA AQTA AQTA QA QA QTAQA QA QA QB QA QA QA QA QA QA QA QA QA QQ AA10 AA17 CC02 CC06 CC10 DD09 DD21 KK04

Claims (3)

[Claims] 1. A laminate in which an aluminum foil, an adhesive layer and a sealant layer are sequentially laminated on a single-layer or multi-layer substrate film, wherein at least the surface of the aluminum foil on the adhesive layer side is subjected to boehmite treatment and adhered. An exterior material for a lithium ion battery, wherein the layer comprises an isocyanate compound. 2. A laminate in which an aluminum foil, an adhesive layer, and a sealant layer are sequentially laminated on a single-layer or multilayer substrate film, wherein both surfaces of the aluminum foil are subjected to boehmite treatment, and the adhesive layer is formed of an isocyanate compound. An exterior material for a lithium ion battery, comprising: 3. The resin film of the sealant layer is laminated on the boehmite-treated surface of the aluminum foil via the adhesive layer by either a melt extrusion lamination method or a heat compression lamination method at 190 ° C. or higher. The exterior material for a lithium ion battery according to claim 1 or 2, wherein: