JP2006069559A - Laminates and packaging materials - Google Patents

Abstract

The present invention provides a laminate and a packaging material in which a laminate adhesive strength between an aluminum foil layer and a thermoplastic resin layer does not decrease even when a content having strong permeability is accommodated.
[Solution]
A packaging material comprising at least the outermost layer film / aluminum foil layer / anchor coat layer / thermoplastic resin layer, wherein the aluminum foil layer and the anchor coat layer are each (1) an aluminum foil layer having a thickness of 5 to 5 A layer comprising a range of 200 μm and having a surface treatment applied to at least the thermoplastic resin layer side. (2) The laminated body and packaging material in which the anchor coat layer is a layer made of an ionic polymer complex.
[Selection figure] None

Description

  The present invention provides a laminate and a package that have excellent adhesion to an aluminum foil layer and that do not lower the adhesive strength even when a strong permeable content such as a lithium battery electrolyte, bathing agent, or poultice is stored. Regarding materials.

  In recent years, lithium batteries that can be ultra-thin and miniaturized have been actively researched and developed as batteries used in portable terminal devices such as personal computers and mobile phones, video cameras, and satellites. Unlike the metal cans conventionally used as packaging materials for batteries, the outer packaging material for lithium batteries is a multilayer film (for example, the outermost layer film) because of its light weight and the ability to freely select the shape of the battery. / A barrier layer / sealant layer) having a bag shape has been used.

  The lithium battery contents are impregnated with a positive electrode material, a negative electrode material, an electrolyte solution in which a lithium salt is dissolved in an aprotic solvent such as propylene carbonate, ethylene carbonate, dimethyl carbonate, diethyl carbonate, and ethyl methyl carbonate, or the electrolyte solution. And an electrolyte layer made of polymer gel. When such a strong permeable solvent passes through the sealant layer, there is a problem that the laminate strength between the aluminum foil layer and the sealant layer is lowered, and the electrolyte solution eventually leaks. It is essential to increase the adhesion strength between layers and to have content resistance.

Moreover, as lithium salt which is an electrolyte of a battery, substances such as LiPF ₆ and LiBF ₄ are used, but these salts generate hydrofluoric acid by hydrolysis reaction with moisture, corrosion of metal surfaces, This is a factor that lowers the laminate strength between the layers of the multilayer film. Further, by using the aluminum foil layer as a barrier layer, moisture intrusion from the surface of the packaging material is substantially blocked.

  However, when using a multilayer film as an outer packaging material for lithium batteries, it is possible to completely block the intrusion of moisture from the end face of the seal part of the sealant layer, which is the innermost layer, because it is bonded by heat sealing. First, it is necessary to further strengthen the laminate strength between the aluminum foil layer and the sealant layer so that the laminate strength is not lowered by the generated hydrofluoric acid.

  In addition, lithium batteries are often used for portable mobile devices and the like, and the usage environment may be as high as 60 to 70 ° C. in a car in midsummer. It is also important to have heat resistance that can maintain the sealing strength.

  In the case of producing a multilayer film, the most common method is dry lamination. Furthermore, as the adhesive used for multilayering, polyester, polyester polyurethane, polyether polyurethane, or the like is used.

  In addition, the packaging for lithium batteries in which the aluminum foil layer in the packaging material is subjected to boehmite treatment and laminated with a thermoplastic resin layer in order to enhance the resistance of the multilayer film to the strongly permeable contents and prevent a decrease in the laminate strength. Materials (for example, see Patent Document 1) are also known.

The prior art documents are shown below.
JP 2003-123707 A

  However, the method of performing the boehmite treatment on the aluminum foil layer requires energy for producing hot water, and further has a low processing capacity and a low processing speed. As a result, there is a problem that the processing cost becomes high.

  In addition, the adhesive used in multilayering has a problem that it has low resistance to strongly permeable contents and causes a decrease in laminate strength.

  The present invention has been made in view of the above-mentioned conventional problems. The purpose of the present invention is to reduce the laminate strength between the aluminum foil layer and the thermoplastic resin layer even if the contents made of a strongly permeable material are packaged. We propose a laminate and packaging material with excellent adhesive strength.

In order to solve the above-mentioned problems, the invention according to claim 1 of the present invention is a packaging material comprising at least the outermost layer film / aluminum foil layer / anchor coat layer / thermoplastic resin layer, wherein the aluminum The foil layer and the anchor coat layer are each a laminate comprising the following layers.
(1) A layer in which the aluminum foil layer has a thickness of 5 to 200 μm, and at least a surface treatment is performed on the thermoplastic resin layer side.
(2) The anchor coat layer is a layer made of an ionic polymer complex.

  Next, in the invention according to claim 2 of the present invention, the ionic polymer complex constituting the anchor coat layer is composed of polyethyleneimine and a polysaccharide having a carboxyl group. Is the body.

  The invention according to claim 3 of the present invention is characterized in that the ionic polymer complex constituting the anchor coat layer is composed of polyethyleneimine and a copolymer of ethylene and a monomer having a carboxyl group. 1. The laminate according to 1.

Next, in the invention according to claim 4 of the present invention, after the anchor coat layer is applied in the range of 0.01 to 1.0 g / m ² on the surface of the aluminum foil layer, the thermoplastic resin layer is laminated. It is a laminated body in any one of Claims 1-3 characterized by the above-mentioned.

  In the invention according to claim 5 of the present invention, the thermoplastic resin is polyethylene, ethylene-α-olefin copolymer, polypropylene, propylene-α-olefin copolymer, or acid based on them. The laminate according to any one of claims 1 to 4, wherein the laminate is a modified polymer or a mixture of two or more thereof.

  Next, the invention according to claim 6 of the present invention is the laminate according to any one of claims 1 to 5, wherein the surface treatment applied to the aluminum foil layer is a treatment containing a zirconium compound. It is.

  The invention according to claim 2 of the present invention is a laminate characterized in that heat treatment is performed after the laminate according to any one of claims 1 to 6 is manufactured.

  Next, the invention according to claim 8 of the present invention is a packaging material using the laminate according to any one of claims 1 to 7 as a minimum unit.

  The invention according to claim 9 of the present invention is a packaging material using the laminate according to any one of claims 1 to 7 as a packaging material for a lithium battery.

  In the present invention, an ionic polymer complex is applied as an anchor coat layer on an aluminum foil layer subjected to treatment containing a zirconium compound, and polyethylene, ethylene-α-olefin copolymer, polypropylene, or propylene-α-olefin is coated. Aluminum foil by being bonded using a copolymer, or an acid-modified polymer based on them, or a thermoplastic resin layer of a mixture of two or more of them, in particular, an acid-modified polymer in a thermoplastic resin layer It is a laminate and a packaging material that have excellent laminate strength between layers including a layer layer and a thermoplastic resin layer, and that do not cause a decrease in adhesive strength.

  In addition, packs with strong penetrable contents, such as lithium battery packaging materials, bathing agent packaging materials, poultices, disinfectants, etc. Since it can be developed for packaging of contents such as the beginning, it is possible to develop applications such as packaging materials, industrial members, and medical members for storing strongly permeable contents.

  Hereinafter, the present invention will be described in detail. The laminate of the present invention comprises at least the structure of outermost layer film / aluminum foil layer / anchor coat layer / thermoplastic resin layer. The aluminum foil layer has a thickness of 5 to 200 μm, and at least a surface treatment is performed on the thermoplastic resin layer side. Further, the anchor coat layer is made of an ionic polymer complex.

  In addition, the aluminum foil layer is used as a barrier layer that blocks moisture from the outside, and in order to improve the laminate strength with the thermoplastic resin layer, the surface of the thermoplastic resin layer side or both surfaces are treated with a zirconium compound. Has been.

The surface of the aluminum foil layer treated with the zirconium compound is at least (1) a water-soluble zirconium compound, (2) a water-soluble or water-dispersible acrylic resin, polyester resin, polyurethane resin, or a mixture thereof. (1) and (2) are both contained, and on the aluminum surface, 0.8 to 35 mg / m ² , a water-soluble or water-dispersible acrylic resin with a water-soluble zirconium compound as zirconium in a dry weight, A film containing 1 to 60 mg / m ^{2 of a} polyester resin or polyurethane resin or a mixture thereof as a solid content is formed.

  Furthermore, the aluminum foil layer having a thickness of about 5 to 200 [mu] m, preferably about 7 to 100 [mu] m can be used in consideration of barrier properties, pinhole resistance and workability. In addition, the material can be a general soft aluminum foil, but especially when used as a packaging material for lithium batteries, the iron content is increased in order to give more pinhole resistance and extensibility during molding. It is desirable to use an aluminum foil in the range of 0.1 to 9.0 wt%, preferably 0.5 to 2.0 wt%. When the iron content is 0.1 wt% or less, pinhole resistance and spreadability cannot be sufficiently imparted, and when it is 9.0 wt% or more, flexibility is impaired.

  In addition, sufficient lamination strength can be obtained even if a thermoplastic resin is laminated directly on an aluminum foil layer treated with a zirconium compound by a method such as extrusion lamination, but it is also resistant to strong penetrating contents. Therefore, an anchor coat layer is formed on the aluminum foil layer by gravure coating or the like.

The anchor coat layer uses an ionic polymer complex. As one of the ionic polymer complexes, a chelate complex with a polysaccharide having a carboxyl group, the main component of which is polyethyleneimine, is used. Examples of polysaccharides include starch, cellulose, chitin, pectin, and plant gum (for example, gum arabic). However, the polysaccharide is not particularly limited, and those obtained by derivatizing these polysaccharides with a carboxyl group are used. Another example is a chelate complex of a monomer and a copolymer containing polyethyleneimine as a main component and having ethylene and a carboxyl group. Representative examples of the monomer having a carboxyl group include acrylic acid such as α, β-unsaturated carboxylic acid, and methacrylic acid, and ionomers obtained by copolymerizing these with ethylene or the like to form a chelate complex. Further, fumaric acid, maleic acid and the like can be used by copolymerizing with ethylene, α-olefin and the like. Both anchor coating agents are chelate complexes with polyethyleneimine, and are superior in moisture resistance, heat resistance, and content resistance due to improved wettability with respect to the aluminum foil layer compared to polyethyleneimine alone.

Further, the anchor coat layer has a coating amount in the range of 0.01 to 1.0 g / m ² , preferably in the range of 0.01 to 0.5 g / m ² or less. When the coating amount is 1.0 g / m ² or more, cohesive peeling at the anchor coat layer may occur and the laminate strength may be lowered. Moreover, if it is 0.018 g / m < ² > or less, a coating film becomes difficult to become uniform.

  Further, extrusion lamination is usually used as a method of providing a thermoplastic resin layer on an aluminum foil layer provided with an anchor coat layer. Further, as the thermoplastic resin layer, polyethylene, ethylene-α-olefin copolymer, polypropylene, propylene-Α-olefin copolymer, acid-modified polymer based on these, or a mixture of two or more of them In consideration of improving the interlayer adhesion strength with the anchor coat layer applied on the aluminum foil layer, an ethylene-α, β-unsaturated carboxylic acid copolymer or its ionic cross-linked product, acid anhydride Acid-modified polymers such as modified polyethylene and acid anhydride-modified polypropylene are preferred.

  Furthermore, the thickness of the thermoplastic resin layer is preferably about 20 to 100 μm, and preferably about 30 to 70 μm. If the thickness is too thin, the sealing strength is weakened, and if it is too thick, the thickness of the entire laminate is increased, resulting in poor sealing.

  Moreover, when the aluminum foil layer used as a barrier layer is formed in the outermost layer, there is a problem that pinholes are generated during processing, distribution, and the like. In order to prevent this, an outermost layer film can be formed outside the aluminum foil layer. As the resin film to be formed, for example, a single layer of a stretched or unstretched film such as a polyester film, a polyamide film, or a polypropylene film, or a multilayer film in which two or more layers are laminated can be used. Further, in order to improve pinhole resistance, a film having a thickness of about 6 to 40 μm is good, and preferably about 12 to 25 μm.

  Furthermore, the outermost layer film and the aluminum foil layer can be bonded together by a known lamination method such as a dry lamination method, a wet lamination method, a non-solvent lamination method, or an extrusion lamination method.

  Furthermore, it is more preferable to perform a heat treatment in order to improve the interlayer adhesion of the laminate. A known heat treatment technique can be used as the heat treatment method. For example, as one method, after producing a laminate composed of the outermost layer film / aluminum foil layer / anchor coat layer / thermoplastic resin layer, a heating and pressing treatment is performed by passing between a heating roll and a press roll. Can be applied.

In addition, this heat treatment method further improves the adhesion between the aluminum foil layer and the thermoplastic resin layer, and remarkably improves the resistance to strongly permeable contents such as the electrolyte used in lithium batteries.

  Furthermore, the laminated body of this invention can also provide a single layer or an intermediate | middle layer between each layer, and can be used as a packaging material for each use.

  Further, as the constitution of the laminate of the present invention, for example, thermoplastic resin layer (outermost layer) / thermoplastic resin layer (intermediate layer) / AL / ac / thermoplastic resin layer, thermoplastic resin layer (outermost layer) / paper Layer (intermediate layer) / AL / ac / thermoplastic resin layer or thermoplastic resin layer (outermost layer) / AL / ac / thermoplastic resin layer (AL is an aluminum foil layer layer, ac is an anchor coat layer, respectively) Show.) The outermost layer and the intermediate layer can be bonded together by a known lamination method such as a dry lamination method, a wet lamination method, a non-solvent lamination method, or an extrusion lamination method.

  Furthermore, the laminate of the present invention thus obtained can be used not only for packaging materials for lithium batteries, but also for many uses such as packaging materials for bath agents, lid materials, packaging materials for poultices, etc. It is.

  Examples of the present invention will be shown below, but the present invention is not limited to these examples.

[Materials used]
<Aluminum foil layer>
・ AL-1 treated with zirconium compound ・ AL-2 not treated <anchor coating agent>
・ Ac-1 Polyethyleneimine / carboxymethylcellulose complex ・ ac-2 Polyethyleneimine / ethylene-acrylic acid copolymer complex <thermoplastic resin (40 μm)>
Resin-1 Low density polyethylene Resin-2 Ethylene-methacrylic acid copolymer Resin-3 Ethylene-methacrylic acid copolymer Zinc ion cross-linked product Resin-4 Maleic anhydride modified polypropylene (random base melting point 140 ° C.)
Resin-5 Maleic anhydride modified polypropylene (homobase melting point 165 ° C.).

[Evaluation sample preparation]
<Sample 1>
A biaxially stretched nylon film having a thickness of 25 μm as an outermost layer and an aluminum foil layer having a thickness of 40 μm were bonded to each other by dry lamination using a urethane-based adhesive. Next, a solid content 0.5 wt% water-methanol solution is applied as an anchor coat layer to the treated surface containing the zirconium compound of the aluminum foil layer so that the coating amount after drying is 0.4 g / m 2 or less, Bonding was performed by extrusion lamination of a thermoplastic resin having a thickness of 40 μm at a processing speed of 80 m / min. Using this sample for evaluation, evaluation was made as a packaging material for the electrolyte solution for a lithium battery.
<Sample 2>
A biaxially stretched polyester film having a thickness of 12 μm as an outermost layer and an aluminum foil layer having a thickness of 7 μm were bonded together by dry lamination using a urethane-based adhesive. Next, a solid content 0.5 wt% water-methanol solution was applied as an anchor coat layer to the treated surface of the aluminum foil layer containing the zirconium compound so that the coating amount after drying was 0.4 g / m ² or less. The thermoplastic resin having a thickness of 40 μm was bonded by extrusion lamination at a processing speed of 80 m / min. This sample for evaluation was used as a packaging material for bathing agents and poultices.

<Treatment method containing zirconium compound>
On the aluminum foil layer of the sample for evaluation, a treatment liquid was prepared in advance with a roll coater so as to have the surface shown below, applied with a coating treatment, and dried at 150 ° C. S-1: The dry weight of the aluminum foil layer surface contains 8 mg / m ² as zirconium in the zirconium compound and 30 mg / m ² as the solid content of acrylic resin.
S-2: As the dry weight of the aluminum foil layer surface, 8 mg / m ² as zirconium in the zirconium compound and 30 mg / m ² as a solid content of a mixture of an acrylic resin and a polyurethane resin are contained.

[Evaluation]
<Evaluation method 1>
The initial laminate strength between the aluminum foil layer and the thermoplastic resin layer of the sample for evaluation was measured. At that time, the sample width was 15 mm, T-type peeling was performed at a peeling speed of 300 mm / min.
<Evaluation method 2>
A sample for evaluation cut to a width of 15 mm was immersed in an electrolyte for lithium battery prepared in an ethylene carbonate / ethyl methyl carbonate = 1/1 solution so that LiPF ₆ was 1.5 N, and the test sample was immersed at 85 ° C. for 2 weeks. After storage, the laminate strength between the aluminum foil layer and the thermoplastic resin layer was measured.
<Evaluation method 3>
A bath powder containing a fragrance component as a volatile strong penetrating substance is placed in a three-sided pouch, sealed and sealed, and stored for one month in a 40 ° C.-90% atmosphere. The laminate strength between the thermoplastic resin layers was measured.
<Evaluation method 4>
A poultice containing methyl salicylate and menthol as a volatile strong penetrating substance is placed in a three-sided pouch, sealed and sealed, and stored at 40 ° C-90% atmosphere for 1 month, and then an aluminum foil layer And the laminate strength between the thermoplastic resin layers was measured.

<Example 1>
An evaluation sample 1 and an evaluation sample 2 were prepared using AL-1 for the aluminum foil layer, S-1 for the surface of the aluminum foil layer, ac-1 for the anchor coating agent, and resin-1 for the thermoplastic resin. Evaluation was performed by methods 1 to 4. The results are shown in Table 1.

<Example 2>
The evaluation sample 1 and the evaluation sample 2 were prepared using AL-1 for the aluminum foil layer, S-1 for the surface of the aluminum foil layer, ac-1 for the anchor coating agent, and resin-2 for the thermoplastic resin. Evaluation was performed by methods 1 to 4. The results are shown in Table 1.

<Example 3>
An evaluation sample 1 and an evaluation sample 2 were prepared using AL-1 for the aluminum foil layer, S-2 for the surface of the aluminum foil layer, ac-2 for the anchor coating agent, and resin-2 for the thermoplastic resin. Evaluation was performed by methods 1 to 4. The results are shown in Table 1.

<Example 4>
The laminated body obtained in Example 3 was subjected to thermal lamination by passing between a heating roll and a press roll at 200 ° C., and an evaluation sample 1 and an evaluation sample 2 were produced. Evaluation was performed by the evaluation methods 1 to 4 using the sample for evaluation. The results are shown in Table 1.

<Example 5>
An evaluation sample 1 and an evaluation sample 2 were prepared using AL-1 for the aluminum foil layer, S-1 for the surface of the aluminum foil layer, ac-2 for the anchor coating agent, and resin-3 for the thermoplastic resin. Evaluation was performed by evaluation according to methods 1 to 4. The results are shown in Table 1.

<Example 6>
The evaluation sample 1 and the evaluation sample 2 were prepared using AL-1 for the aluminum foil layer, S-1 for the surface of the aluminum foil layer, ac-1 for the anchor coating agent, and resin-4 for the thermoplastic resin. Evaluation was performed by methods 1 to 4. The results are shown in Table 1.

<Example 7>
An evaluation sample 1 and an evaluation sample 2 were prepared using AL-1 for the aluminum foil layer, S-2 for the surface of the aluminum foil layer, ac-2 for the anchor coating agent, and resin-5 for the thermoplastic resin. Evaluation was performed by methods 1 to 4. The results are shown in Table 1.

<Example 8>
The laminated body obtained in Example 7 was subjected to thermal lamination by passing between a heating roll and a press roll at 200 ° C., and an evaluation sample 1 and an evaluation sample 2 were produced. Evaluation was performed by the evaluation methods 1 to 4 using the sample for evaluation. The results are shown in Table 1.

<Comparative Example 1>
Evaluation sample 1 and evaluation sample 2 were prepared using AL-2 for the aluminum foil layer, ac-1 for the anchor coating agent, and resin-1 for the thermoplastic resin, and the evaluation methods 1 to 4 were performed. The results are shown in Table 1.

<Comparative example 2>
Samples for evaluation were prepared using AL-2 for the aluminum foil layer, ac-1 for the anchor coating agent, and resin-2 for the thermoplastic resin, and evaluation was performed by the evaluation methods 1 to 4. The results are shown in Table 1.

<Comparative Example 3>
An evaluation sample 1 and an evaluation sample 2 were prepared using AL-2 for the aluminum foil layer, ac-2 for the anchor coating agent, and resin-2 for the thermoplastic resin, and evaluated by the evaluation methods 1 to 4. . The results are shown in Table 1.

<Comparative example 4>
The laminated body obtained in Comparative Example 3 was subjected to thermal lamination by passing it between a 200 ° C. heating roll and a press roll to produce Evaluation Sample 1 and Evaluation Sample 2. Evaluation was performed by the evaluation methods 1 to 4 using the sample for evaluation. The results are shown in Table 1.

<Comparative Example 5>
Evaluation sample 1 and evaluation sample 2 were prepared using AL-2 for the aluminum foil layer, ac-2 for the anchor coating agent, and resin-3 for the thermoplastic resin, and the evaluation methods 1 to 4 were performed. The results are shown in Table 1.

<Comparative Example 6>
Evaluation sample 1 and evaluation sample 2 were prepared using AL-2 for the aluminum foil layer, ac-1 for the anchor coating agent, and resin-4 for the thermoplastic resin, and the evaluation methods 1 to 4 were performed. The results are shown in Table 1.

<Comparative Example 7>
The evaluation sample 1 and the evaluation sample 2 were prepared using AL-2 for the aluminum foil layer, ac-2 for the anchor coating agent, and resin-5 for the thermoplastic resin, and evaluated by the evaluation methods 1 to 4 described above. . The results are shown in Table 1.

<Comparative Example 8>
The laminated body obtained in Comparative Example 7 was subjected to thermal lamination by passing between a 200 ° C. heating roll and a press roll to prepare an evaluation sample. Evaluation was performed by the evaluation methods 1 to 4 using the sample for evaluation. The results are shown in Table 1.

（表１）はアルミニウム箔層と熱可塑性樹脂層間の初期ラミネート強度と強浸透性物質保存後のラミネート強度評価等の結果である。

Table 1 shows the results of initial laminate strength between the aluminum foil layer and the thermoplastic resin layer and evaluation of laminate strength after storage of the strong permeable material.

  The laminate and the packaging material of the present invention can be used as a packaging material for lithium batteries, a bath agent, and a packaging material for strongly permeable substances such as poultices. It is a wonderful invention that can be used in a wide range of fields.

Claims (9)

A packaging material comprising at least the outermost layer film / aluminum foil layer / anchor coat layer / thermoplastic resin layer, wherein the aluminum foil layer and the anchor coat layer are composed of the following layers, respectively. body.
(1) A layer in which the aluminum foil layer has a thickness of 5 to 200 μm, and at least a surface treatment is performed on the thermoplastic resin layer side.
(2) The anchor coat layer is a layer made of an ionic polymer complex.   2. The laminate according to claim 1, wherein the ionic polymer complex constituting the anchor coat layer is composed of polyethyleneimine and a polysaccharide having a carboxyl group.   2. The laminate according to claim 1, wherein the ionic polymer complex constituting the anchor coat layer is composed of polyethyleneimine and a copolymer of ethylene and a monomer having a carboxyl group. The thermoplastic resin layer is laminated after applying the anchor coat layer on the surface of the aluminum foil layer in a range of 0.01 to 1.0 g / m ^2. The laminated body of description.   The thermoplastic resin may be polyethylene, ethylene-α-olefin copolymer, polypropylene, propylene-α-olefin copolymer, acid-modified polymer based on them, or a mixture of two or more of them. The laminate according to any one of claims 1 to 4, wherein the laminate is provided.   The laminate according to any one of claims 1 to 5, wherein the surface treatment applied to the aluminum foil layer is a treatment containing a zirconium compound.   The laminated body which heat-processed after producing the laminated body in any one of Claims 1-6.   A packaging material using the laminate according to any one of claims 1 to 7 as a minimum unit.   A packaging material comprising the laminate according to claim 1 as a packaging material for a lithium battery.