JP6710894B2 - Battery packaging material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a battery packaging material having excellent ink printing characteristics on the surface of a base material layer.

Conventionally, various types of batteries have been developed, but in all batteries, a packaging material is an indispensable member for sealing battery elements such as electrodes and electrolytes. Conventionally, metal packaging materials have been widely used for battery packaging, but in recent years, as electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc. have become more sophisticated, batteries are required to have various shapes. At the same time, it is required to be thinner and lighter. However, the metal battery packaging materials that have been widely used in the past have the drawbacks that it is difficult to follow the diversification of shapes and there is a limit to weight reduction.

Therefore, as a battery packaging material that can be easily processed into various shapes and that can be made thinner and lighter, we propose a film-like laminate in which the base material layer/adhesive layer/metal layer/sealant layer are sequentially laminated. (For example, see Patent Document 1). Such a film-shaped battery packaging material is formed so that the battery element can be sealed by making the sealant layers face each other and heat-sealing the peripheral portions by heat sealing.

In various packaging materials formed by the above laminated body, ink is printed on the surface of the base material layer to form barcodes, patterns, characters, etc., and adhered on the base material layer on the printed side. A method of printing on a packaging material (generally called back printing) by a method of laminating an agent and a metal foil is widely adopted. However, when such a printed surface is present between the base material layer and the metal layer, the adhesion between the base material layer and the metal layer is deteriorated, and delamination easily occurs between the layers. In particular, since the battery to which the battery packaging material is applied is required to have high safety, such a method of printing by back printing is shunned in the battery packaging material. Therefore, conventionally, when a print such as a bar code is formed on a battery packaging material, a method in which a seal having the print formed thereon is attached to the surface of the base material layer is generally used.

However, if a seal with a print is attached to the surface of the base material layer, the thickness and weight of the battery packaging material increase. Therefore, in view of the recent trend toward thinner and lighter packaging materials for batteries, a method of printing with ink directly on the surface of the base material layer of the packaging material for batteries has been studied.

Pad printing (also referred to as tampo printing) is known as a method of printing ink directly on the surface of a base material layer of a battery packaging material. Pad printing is the following printing method. First, ink is poured into the concave portion of the flat plate on which the pattern to be printed is etched. Next, the silicon pad is pressed against the concave portion to transfer the ink to the silicon pad. Next, the ink transferred to the surface of the silicon pad is transferred to the print target, and the ink is applied to the print target. In such pad printing, since the ink is transferred to the print target using an elastic silicon pad, it is easy to print on the surface of the battery packaging material after molding, and the battery element can be used as a battery packaging material. It has the advantage that it can be printed on the battery after sealing.

By the way, a polyamide resin film such as nylon is generally used for the base material layer of the battery packaging material, and the polyamide resin film generally contains ethylenebisoleic acid amide as a water repellent. By including the water repellent, the wettability of the molten resin to water can be adjusted during the production of the film, and appropriate unevenness (surface roughness) can be formed on the surface of the raw film, and the raw film can be formed. Even after stretching, the uneven shape remains, and a polyamide resin film having a surface slipperiness adjusted can be obtained.

JP 2008-287971 A

However, as a result of investigations by the present inventors, when a polyamide resin film containing ethylenebisoleic acid amide as a water repellent is used for a base material layer, after encapsulating a battery element such as an electrolytic solution in a battery packaging material, When heat is applied in the baking process, ethylene bisoleic acid amide bleeds out on the surface of the base layer, and when ink is printed on the surface of the base layer by pad printing or the like, the ink is repelled on the surface of the base layer. As a result, it became clear that the ink is hard to be fixed and there may be a missing portion where the ink is not formed. In particular, it has been clarified that the printability tends to be insufficient when printed by pad printing.
Under such circumstances, the main object of the present invention is to provide a battery packaging material having excellent printing characteristics of ink on the surface of a base material layer formed of a polyamide resin film. Another object of the present invention is to provide a method for producing the battery packaging material, and a battery using the battery packaging material.

The present inventors have diligently studied to solve the above problems. As a result, in at least a battery packaging material composed of a laminate in which a base material layer, a metal layer, and a sealant layer are sequentially laminated, the base material layer is formed of a polyamide resin containing ethylenebisstearic acid amide. It has been found that the printing characteristics of the ink on the surface of the base material layer can be effectively enhanced by the presence of the above. The present invention has been completed by further studies based on these findings.

That is, the present invention provides the inventions of the following modes.
Item 1. At least a base material layer, a metal layer, and a sealant layer consisting of a laminated body sequentially laminated,
The base material layer is formed of a polyamide resin containing ethylenebisoleic acid amide,
A packaging material for a battery, wherein the content of ethylenebisoleic acid amide in the base material layer is 400 ppm or less.
Item 2. Item 2. The battery packaging material according to Item 1, which is used by printing ink on at least a part of the surface of the base material layer.
Item 3. Item 2. The battery packaging material according to Item 1, wherein ink is printed on at least a part of the surface of the base material layer.
Item 4. Item 1. The ethylene bisoleic acid amide present on the surface of the base material layer in the range of 210 mm x 297 mm is 380 µg or less after standing the battery packaging material in a constant temperature bath at 100°C for 24 hours. The packaging material for a battery according to any one of 1.
Item 5. Wetting tension of the substrate layer surface, 32 mN is / m or more, the battery packaging material according to any one of claim 1 to 4.
Item 6. Item 6. The battery packaging material according to any one of Items 1 to 5, wherein the polyamide resin is biaxially stretched nylon.
Item 7. Item 7. The battery packaging material according to any one of Items 1 to 6, wherein an adhesive layer is laminated between the base material layer and the metal layer.
Item 8. Item 8. The battery packaging material according to any one of Items 1 to 7, wherein an adhesive layer is laminated between the metal layer and the sealant layer.
Item 9. Item 9. The battery packaging material according to any one of Items 1 to 8, wherein the metal layer is formed of an aluminum foil.
Item 10. A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is housed in the battery packaging material according to any one of Items 1 to 9.

ADVANTAGE OF THE INVENTION According to this invention, the packaging material for batteries excellent in the printing characteristic of the ink on the surface of a base material layer can be provided. Further, according to the present invention, it is possible to provide a battery using the battery packaging material and a method for manufacturing the battery packaging material.

It is a figure which shows an example of the cross-section of the packaging material for batteries of this invention. It is a figure which shows an example of the cross-section of the packaging material for batteries of this invention.

The battery packaging material of the present invention comprises at least a laminate in which a base material layer, a metal layer, and a sealant layer are sequentially laminated, and the base material layer is formed of a polyamide resin containing ethylenebisstearic acid amide. It is characterized by Hereinafter, the battery packaging material of the present invention, the method for producing the battery packaging material, and the battery using the battery packaging material will be described in detail.

1. Laminated Structure of Battery Packaging Material As shown in FIG. 1, the battery packaging material of the present invention comprises a laminate in which at least a base material layer 1, a metal layer 3, and a sealant layer 4 are sequentially laminated. In the battery packaging material of the present invention, the base material layer 1 is the outermost layer and the sealant layer 4 is the innermost layer. That is, at the time of assembling the battery, the sealant layers 4 located at the periphery of the battery element are heat-sealed to seal the battery element, thereby sealing the battery element.

In the battery packaging material of the present invention, as shown in FIG. 1, an adhesive layer 2 is provided between the base material layer 1 and the metal layer 3 as needed for the purpose of enhancing the adhesiveness between them. Good. Further, as shown in FIG. 2, an adhesive layer 5 may be provided between the metal layer 3 and the sealant layer 4, if necessary, for the purpose of enhancing the adhesiveness between them.

2. Composition of each layer forming the battery packaging material [base material layer 1]
In the battery packaging material of the present invention, the base material layer 1 is the outermost layer. The base material layer 1 is formed of a polyamide resin containing ethylenebisstearic acid amide.

The polyamide resin is preferably nylon. Specific examples of the polyamide resin include nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and aliphatic polyamides such as copolymers of nylon 6 and nylon 6,6; terephthalic acid and/or isophthalic acid. Hexamethylenediamine-isophthalic acid-terephthalic acid copolymerized polyamides such as nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid) containing the derived constitutional unit, polymeta-xylylene adipa Polyamide containing aromatics such as amide (MXD6); alicyclic polyamide such as polyaminomethylcyclohexyl adipamide (PACM6); further copolymerized with lactam component and isocyanate component such as 4,4′-diphenylmethane-diisocyanate Polyamides, polyester amide copolymers and polyether ester amide copolymers which are copolymers of polyamides and copolymerized polyamides and polyesters and polyalkylene ether glycols; and these copolymers. These polyamide resins may be used alone or in combination of two or more.

The base material layer 1 may be formed of a uniaxially or biaxially stretched polyamide resin film, or may be formed of an unstretched polyamide resin film. The stretched polyamide resin film has excellent stretchability, can prevent whitening due to resin cracking of the base material layer 1 during molding, and is suitably used as a material for forming the base material layer 1. Among the stretched polyamide resin films, the uniaxially or biaxially stretched polyamide resin film, especially the biaxially stretched polyamide resin film (particularly biaxially stretched nylon) has improved heat resistance due to oriented crystallization. Therefore, it is suitably used as the base material layer 1.

In the present invention, the polyamide resin contains ethylenebisstearic acid amide. Ethylenebisstearic acid amide suitably functions as a water repellent agent in the polyamide resin forming the base material layer 1. Specifically, when the polyamide resin contains ethylene bis-stearic acid amide, the wettability of the molten resin to water is adjusted during the production of the polyamide resin film, and the surface of the raw film has an appropriate unevenness (surface roughness). It is possible to form a polyamide resin film in which the unevenness remains even after stretching of the original film and the surface slipperiness is adjusted. The polyamide resin forming the base material layer 1 may contain ethylene bisoleic acid amide that is conventionally widely used as a water repellent, but from the viewpoint of improving the printability of the base material layer surface, it is substantially preferable. It is preferable that it does not contain ethylene bisoleic acid amide.

In the polyamide resin forming the base material layer 1, the content of ethylenebisstearic acid amide is not particularly limited, but is preferably about 1 to 600 ppm, more preferably about 50 to 500 ppm, and further preferably about 100 to 400 ppm. Can be mentioned. In the present invention, the content of ethylenebisstearic acid amide in the polyamide resin forming the base material layer 1 is the total amount of ethylenebisstearic acid amide present inside and on the surface of the polyamide resin. The content of ethylenebisstearic acid amide in the polyamide resin constituting the base material layer 1 of the battery packaging material is determined by removing the base material layer 1 from the battery packaging material and dissolving the base material layer 1 in hexafluoroisopropyl alcohol. After that, dimethylethane is added to cause solvent precipitation, the resin component is separated, an extraction solution of ethylenebisoleic acid amide is prepared, and the extraction solution can be quantified by GC-MS analysis.

Further, in the battery packaging material of the present invention, after the battery packaging material is allowed to stand in a constant temperature bath at 100° C. for 24 hours, ethylene existing on the surface of the base material layer in the range of 210 mm×297 mm (A4 size). The amount of bisstearic acid amide is preferably 30 μg or less. Allowing the packaging material for a battery to stand in a constant temperature bath at 100° C. for 24 hours is a treatment imitating a baking step during the production of a battery cell, and ethylenebisstearin that bleeds out to the surface of the base material layer 1 by the treatment. By setting the amount of the acid amide to 30 μg/A4 size or less, the ink is not easily repelled on the surface of the base material layer 1 and a packaging material for a battery having further excellent printability can be obtained. Ethylenebisstearic acid amide is less likely to bleed out due to heating as compared with ethylenebisoleic acid amide, and therefore, for example, when the content of ethylenebisstearic acid amide in the polyamide resin is in the above range, The amount of ethylenebisstearic acid amide that bleeds out on the surface of the base material layer 1 by the above-mentioned baking treatment can be preferably set to 30 μg/A4 size or less. The amount of the ethylenebisstearic acid amide in the battery packaging material is a value measured by the method described in Examples below.

The base material layer 1 may be formed by laminating a resin different from a polyamide resin and a polyamide resin in order to improve the pinhole resistance and the insulating property of the battery package. For example, a multilayer structure in which a polyester film and a nylon film are laminated, a multilayer structure in which a biaxially stretched polyester and a biaxially stretched nylon are laminated, and the like can be mentioned. In the present invention, when the base material layer 1 has a multilayer structure, a polyamide resin is arranged on the outermost surface side (the side opposite to the metal layer 3). When the base material layer 1 has a multi-layer structure, the resin films may be adhered via an adhesive or may be directly laminated without an adhesive. In the case of adhering without using an adhesive, for example, a method of adhering in a hot melt state such as a co-extrusion method, a sand laminating method, or a thermal laminating method can be mentioned. When the adhesive is used for the adhesion, the adhesive to be used may be a two-component curing type adhesive or a one-component curing type adhesive. Further, the adhesion mechanism of the adhesive is not particularly limited, and may be any of chemical reaction type, solvent volatilization type, heat melting type, heat pressure type, electron beam curing type such as UV and EB. Polyester resin, polyether resin, polyurethane resin, epoxy resin, phenol resin resin, polyamide resin, polyolefin resin, polyvinyl acetate resin, cellulose resin, (meth)acrylic resin as a component of the adhesive. Examples thereof include resins, polyimide resins, amino resins, rubber, and silicon resins.

In the battery packaging material of the present invention, the wettability of the surface of the base material layer 1 is preferably 32 mN/m or more. When the wetting tension of the surface of the base material layer 1 is 32 mN/m or more, the ink is not easily repelled on the surface of the base material layer 1, and the printability can be further improved. In particular, when ink is printed by pad printing on a battery packaging material in which a lubricant is present on the surface of the base material layer to improve moldability, the ink is repelled on the surface of the base material layer 1 and printing failure occurs. However, even in such a case, the base material layer 1 is formed of a polyamide resin containing a predetermined amount or less of ethylene bisoleic acid amide, and the wetting tension of the surface of the base material layer 1 is 32 mN. When it is /m or more, the ink is not easily repelled, and it is particularly suitable as a battery packaging material in which printing or the like is formed on the surface of the base material layer by pad printing.

In the packaging material for a battery of the present invention, the wetting tension of the surface of the base material layer 1 is more preferably about 32 to 50 mN/m , further preferably from the viewpoint of improving printability while enhancing moldability. It is about 35 to 45 mN/m .

In addition, in this invention, the wetting tension of the packaging material for batteries is a value measured by the method based on the regulation of JIS K6768:1999, and a concrete method is as having described in an Example.

The thickness of the base material layer 1 is, for example, about 10 to 50 μm, preferably about 12 to 30 μm.

In the battery packaging material of the present invention, the ink can be suitably printed on at least a part of the surface of the base material layer 1. That is, in the present invention, in the battery packaging material in which ink is printed on the surface of the base material layer 1, the ink (cured product of ink, dried material, etc.) printed on the surface of the base material layer 1 is exposed. . The printed ink can form, for example, a print such as a barcode, a pattern, or a character. The ink used for printing is not particularly limited, and known ones can be used. For example, a photocurable ink that is cured by irradiation with ultraviolet rays or the like can be used.

[Adhesive layer 2]
In the battery packaging material of the present invention, the adhesive layer 2 is a layer that is provided as necessary to bond the base material layer 1 and the metal layer 3 together.

The adhesive layer 2 is formed of an adhesive that can bond the base material layer 1 and the metal layer 3 together. The adhesive used for forming the adhesive layer 2 may be a two-component curable adhesive or a one-component curable adhesive. Further, the adhesion mechanism of the adhesive used for forming the adhesive layer 2 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a hot pressing type and the like.

Specific examples of the resin component of the adhesive that can be used for forming the adhesive layer 2 include polyester-based resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and copolyester. Resin: Polyether-based adhesive; Polyurethane-based adhesive; Epoxy-based resin; Phenolic resin-based resin; Nylon 6, Nylon 66, Nylon 12, polyamide-based resin such as copolyamide; Polyolefin, acid-modified polyolefin, metal-modified polyolefin, etc. Polyolefin resin; polyvinyl acetate resin; cellulose adhesive; (meth)acrylic resin; polyimide resin; urea resin, amino resin such as melamine resin; chloroprene rubber, nitrile rubber, rubber such as styrene-butadiene rubber Silicone resin; fluorinated ethylene propylene copolymer and the like. These adhesive components may be used alone or in combination of two or more. The combination mode of two or more adhesive components is not particularly limited, but for example, as the adhesive component, a mixed resin of polyamide and acid-modified polyolefin, a mixed resin of polyamide and metal-modified polyolefin, polyamide and polyester, Examples include mixed resins of polyester and acid-modified polyolefin, mixed resins of polyester and metal-modified polyolefin, and the like. Among these, the extensibility, the durability under high humidity conditions, the effect of suppressing yellowing, the effect of suppressing heat deterioration during heat sealing, etc. are excellent, and the reduction of the lamination strength between the base material layer 1 and the metal layer 3 is suppressed. From the viewpoint of effectively suppressing the occurrence of delamination, polyurethane-based two-component curing type adhesives; polyamide, polyester, or a blend resin of these and a modified polyolefin is preferable.

Further, the adhesive layer 2 may be multilayered with different adhesive components. When the adhesive layer 2 is multilayered with different adhesive components, from the viewpoint of improving the lamination strength of the base layer 1 and the metal layer 3, the adhesive component disposed on the base layer 1 side is used as the base layer 1. It is preferable to select a resin having excellent adhesiveness to the metal layer 3 and an adhesive component having excellent adhesiveness to the metal layer 3 as the adhesive component disposed on the metal layer 3 side. When the adhesive layer 2 is multilayered with different adhesive components, specifically, the adhesive component disposed on the metal layer 3 side is preferably an acid-modified polyolefin, a metal-modified polyolefin, a polyester and an acid-modified polyolefin. Examples of the mixed resin, a resin containing a copolyester, and the like.

The thickness of the adhesive layer 2 is, for example, about 2 to 50 μm, preferably about 3 to 25 μm.

[Metal layer 3]
In the battery packaging material of the present invention, the metal layer 3 is a layer that not only improves the strength of the packaging material but also functions as a barrier layer for preventing water vapor, oxygen, light and the like from entering the inside of the battery. Specific examples of the metal forming the metal layer 3 include metal foils such as aluminum (aluminum alloy), stainless steel, and titanium. Among these, aluminum or stainless steel is preferably used. In order to prevent wrinkles and pinholes during the production of the packaging material, soft aluminum, for example, annealed aluminum (JIS A8021P-O) or (JIS A8079P-O) is used as the metal layer 3 in the present invention. Is preferred.

The thickness of the metal layer 3 is, for example, about 10 to 200 μm, preferably about 20 to 100 μm.

Further, the metal layer 3 is preferably subjected to chemical conversion treatment on at least one surface, preferably at least the surface on the sealant layer 4 side, and more preferably both surfaces, for the purpose of stabilizing adhesion, preventing dissolution and corrosion. .. Here, the chemical conversion treatment is a treatment for forming an acid resistant film on the surface of the metal layer 3. The chemical conversion treatment is, for example, a chromate chromate treatment using a chromate compound such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, acetyl acetate chromate, chromium chloride, and chromium chromium sulfate. A phosphoric acid chromate treatment using a phosphoric acid compound such as sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid; an aminated phenol polymer composed of repeating units represented by the following general formulas (1) to (4) Examples include chromate treatment using coalescence. In the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more. Good.

In formulas (1) to (4), X represents a hydrogen atom, a hydroxyl group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. R ¹ and R ² are the same or different and each represents a hydroxyl group, an alkyl group, or a hydroxyalkyl group. In the general formulas (1) to (4), examples of the alkyl group represented by X, R ¹ and R ² include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, Examples thereof include linear or branched alkyl groups having 1 to 4 carbon atoms such as tert-butyl group. Examples of the hydroxyalkyl group represented by X, R ¹ and R ² include a hydroxymethyl group, a 1-hydroxyethyl group, a 2-hydroxyethyl group, a 1-hydroxypropyl group, a 2-hydroxypropyl group and a 3-hydroxypropyl group. Linear or branched chain having 1 to 4 carbon atoms in which one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group and 4-hydroxybutyl group is substituted. An alkyl group is mentioned. In the general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxyl group, or a droxyalkyl group. The number average molecular weight of the aminated phenol polymer comprising the repeating units represented by the general formulas (1) to (4) is, for example, about 500 to about 1,000,000, preferably about 1000 to about 20,000.

As a chemical conversion treatment method for imparting corrosion resistance to the metal layer 3, phosphoric acid is coated with a dispersion of metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide and fine particles of barium sulfate, A method of forming a corrosion resistant treatment layer on the surface of the metal layer 3 by performing a baking treatment at 150° C. or higher can be mentioned. Further, a resin layer obtained by crosslinking a cationic polymer with a crosslinking agent may be formed on the anticorrosion treated layer. Here, as the cationic polymer, for example, polyethyleneimine, an ionic polymer complex composed of a polymer having polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is grafted to an acrylic main skeleton, polyallylamine or The derivative, aminophenol, etc. are mentioned. These cationic polymers may be used alone or in combination of two or more. Examples of the cross-linking agent include a compound having at least one functional group selected from the group consisting of an isocyanate group, a glycidyl group, a carboxyl group, and an oxazoline group, a silane coupling agent, and the like. These cross-linking agents may be used alone or in combination of two or more.

For these chemical conversion treatments, one type of chemical conversion treatment may be performed alone, or two or more types of chemical conversion treatment may be performed in combination. Furthermore, these chemical conversion treatments may be performed using one type of compound alone, or may be performed using two or more types of compounds in combination. Among these, a chromate treatment is preferable, and a chromate treatment in which a chromate compound, a phosphoric acid compound, and an aminated phenol polymer are combined is more preferable.

The amount of the acid resistant film formed on the surface of the metal layer 3 in the chemical conversion treatment is not particularly limited, but for example, in the case of performing a chromate treatment by combining a chromic acid compound, a phosphoric acid compound, and an aminated phenol polymer. The chromic acid compound is about 0.5 to about 50 mg in terms of chromium, preferably about 1.0 to about 40 mg, and the phosphorus compound is about 0.5 to about 50 mg in terms of phosphorus per 1 m ² of the surface of the metal layer 3, preferably Of about 1.0 to about 40 mg, and the aminated phenolic polymer in an amount of about 1 to about 200 mg, preferably about 5.0 to 150 mg.

The chemical conversion treatment is performed by applying a solution containing a compound used for forming an acid resistant film to the surface of the metal layer 3 by a bar coating method, a roll coating method, a gravure coating method, a dipping method, or the like, and then applying the temperature of the metal layer 3. Is heated to about 70 to 200°C. Further, before subjecting the metal layer 3 to the chemical conversion treatment, the metal layer 3 may be previously subjected to a degreasing treatment by an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method or the like. By performing the degreasing treatment in this way, the chemical conversion treatment of the surface of the metal layer 3 can be performed more efficiently.

[Sealant layer 4]
In the battery packaging material of the present invention, the sealant layer 4 corresponds to the innermost layer and is a layer that seals the battery element by heat-sealing the sealant layers during the assembly of the battery.

The resin component used in the sealant layer 4 is not particularly limited as long as it can be heat-welded, and examples thereof include polyolefin, cyclic polyolefin, carboxylic acid-modified polyolefin, and carboxylic acid-modified cyclic polyolefin.

Specific examples of the polyolefin include polyethylene such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene; homopolypropylene, polypropylene block copolymer (for example, propylene-ethylene block copolymer), polypropylene. Random copolymers (for example, random copolymers of propylene and ethylene); ethylene-butene-propylene terpolymers; and the like. Among these polyolefins, polyethylene and polypropylene are preferable.

The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, isoprene, and the like. Is mentioned. Examples of the cyclic monomer which is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene and norbornadiene. Among these polyolefins, cyclic alkenes are preferable, and norbornene is more preferable.

The carboxylic acid-modified polyolefin is a polymer modified by subjecting the polyolefin to block polymerization or graft polymerization with a carboxylic acid. Examples of the carboxylic acid used for modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride.

The carboxylic acid-modified cyclic polyolefin is obtained by copolymerizing a part of the monomers constituting the cyclic polyolefin by substituting α,β-unsaturated carboxylic acid or its anhydride, or by adding α,β to the cyclic polyolefin. -A polymer obtained by block-polymerizing or graft-polymerizing an unsaturated carboxylic acid or an anhydride thereof. The cyclic polyolefin modified with carboxylic acid is the same as described above. The carboxylic acid used for modification is the same as that used for modifying the acid-modified cycloolefin copolymer.

Among these resin components, carboxylic acid-modified polyolefin is preferable; and carboxylic acid-modified polypropylene is more preferable.

The sealant layer 4 may be formed of one type of resin component alone, or may be formed of a blend polymer in which two or more types of resin components are combined. Further, the sealant layer 4 may be formed of only one layer, but may be formed of two or more layers with the same or different resin components.

In the battery packaging material of the present invention, the sealant layer 4 may contain a lubricant. The type of lubricant is not particularly limited, and examples thereof include those exemplified in the item [Base material layer 1] above. When the sealant layer 4 contains a lubricant, the content thereof may be appropriately selected, but is preferably about 700 to 1200 ppm, more preferably about 800 to 1100 ppm. In the present invention, the content of the lubricant in the sealant layer 4 is the total amount of the lubricant present inside the sealant layer 4 and the lubricant present on the surface of the sealant layer 4.

The thickness of the sealant layer 4 can be appropriately selected, but it is about 10 to 100 μm, preferably about 15 to 50 μm.

[Adhesive layer 5]
In the battery packaging material of the present invention, the adhesive layer 5 is a layer provided between the metal layer 3 and the sealant layer 4 as needed in order to firmly bond them together.

The adhesive layer 5 is formed of an adhesive that can bond the metal layer 3 and the sealant layer 4 together. Regarding the adhesive used for forming the adhesive layer 5, the adhesive mechanism, the kind of the adhesive component, and the like are the same as in the case of the adhesive layer 2. The adhesive component used in the adhesive layer 5 is preferably a polyolefin resin, more preferably a carboxylic acid-modified polyolefin, and particularly preferably a carboxylic acid-modified polypropylene.

The thickness of the adhesive layer 5 is, for example, 2 to 50 μm, preferably 15 to 30 μm.

3. Method for producing battery packaging material The method for producing the battery packaging material of the present invention is not particularly limited, as long as a laminate obtained by laminating each layer having a predetermined composition is obtained, but for example, the following method is exemplified. ..

First, a laminated body (hereinafter, also referred to as “laminated body A”) in which the base material layer 1, the adhesive layer 2, and the metal layer 3 are laminated in order is formed. Specifically, the laminate A is formed by using an extrusion method, a gravure coat method, an adhesive used for forming the adhesive layer 2 on the base material layer 1 or on the metal layer 3 whose surface has been subjected to chemical conversion treatment, if necessary. After coating and drying by a coating method such as a coating method or a roll coating method, the metal layer 3 or the base material layer 1 is laminated and the adhesive layer 2 is cured by a dry lamination method.

Then, the sealant layer 4 is laminated on the metal layer 3 of the laminate A. When the sealant layer 4 is directly laminated on the metal layer 3, the resin component forming the sealant layer 4 may be applied on the metal layer 3 of the laminate A by a method such as a gravure coating method or a roll coating method. .. When the adhesive layer 5 is provided between the metal layer 3 and the sealant layer 4, for example, (1) the adhesive layer 5 and the sealant layer 4 are laminated on the metal layer 3 of the laminate A by coextrusion. Method (coextrusion lamination method), (2) a method of separately forming a laminated body in which the adhesive layer 5 and the sealant layer 4 are laminated, and laminating this on the metal layer 3 of the laminated body A by the thermal lamination method, ( 3) An adhesive for forming the adhesive layer 5 is laminated on the metal layer 3 of the laminate A by an extrusion method, a solution coating method, a drying method at a high temperature, or a baking method, and the sheet shape is preliminarily formed on the adhesive layer 5. A method of laminating the sealant layer 4 formed into a film by a thermal lamination method, (4) a melted adhesive layer 5 between the metal layer 3 of the laminate A and the sealant layer 4 formed into a sheet in advance. A method (sand lamination method) of bonding the laminate A and the sealant layer 4 via the adhesive layer 5 while pouring them in may be mentioned. In addition, in order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 that is provided as necessary, you may provide to the heat processing of a hot-roll contact type, a hot air type, a near or far infrared type, etc. The conditions for such heat treatment include, for example, 150 to 250° C. and 1 to 5 minutes.

In the battery packaging material of the present invention, each layer constituting the laminate improves or stabilizes film-forming properties, lamination processing, final product secondary processing (pouching, embossing) suitability, etc., if necessary. Therefore, surface activation treatment such as corona treatment, blast treatment, oxidation treatment, and ozone treatment may be performed.

Further, when the ink is printed on the surface of the battery packaging material, the printing method is not particularly limited, but when printing on the molded battery packaging material, pad printing is preferable. Since the base material layer of the battery packaging material obtained by the production method of the present invention is formed of a polyamide resin containing ethylenebisstearic acid amide, the ink is not easily repelled, and the ink is preferably printed by pad printing. It can be performed. Therefore, it is possible to preferably form, for example, a print such as a barcode, a pattern, or a character on at least a part of the surface of the base material layer 1. The ink used for printing is as described above.

4. Use of Battery Packaging Material The battery packaging material of the present invention is used as a packaging material for hermetically containing battery elements such as a positive electrode, a negative electrode and an electrolyte.

Specifically, a battery element having at least a positive electrode, a negative electrode, and an electrolyte, in the battery packaging material of the present invention, in a state where the metal terminals connected to each of the positive electrode and the negative electrode are projected outward, By covering the periphery of the element so that a flange portion (a region where the sealant layers contact each other) can be formed and sealing the sealant layers of the flange portion by heat sealing, a battery using a battery packaging material can be obtained. Provided. When a battery element is accommodated by using the battery packaging material of the present invention, the sealant portion of the battery packaging material of the present invention is used so that the sealant portion is on the inner side (the surface in contact with the battery element).

Since the battery packaging material of the present invention is used in the battery of the present invention, the ink is preferably printed on the surface of the battery after the battery packaging material is molded and the battery element is sealed. You can That is, in the battery of the present invention, since the base material layer of the battery packaging material is formed of the polyamide resin containing ethylenebisstearic acid amide, the ink is preferably printed easily by ink-sensitive pad printing. It is possible to carry out, and it is possible to suitably form, for example, a print such as a bar code, a pattern, or a character on at least a part of the surface of the battery.

The battery packaging material of the present invention may be used in either a primary battery or a secondary battery, but is preferably a secondary battery. The type of the secondary battery to which the battery packaging material of the present invention is applied is not particularly limited, and examples thereof include a lithium ion battery, a lithium ion polymer battery, a lead storage battery, a nickel/hydrogen storage battery, and a nickel/cadmium storage battery. , Nickel/iron storage battery, nickel/zinc storage battery, silver oxide/zinc storage battery, metal-air battery, polyvalent cation battery, capacitor, capacitor and the like. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are mentioned as suitable targets for application of the battery packaging material of the present invention.

The present invention will be described in detail below with reference to Examples and Comparative Examples. However, the present invention is not limited to the examples.

Examples 1-5 and Comparative Example 1
<Manufacturing of packaging materials for batteries>
By laminating the adhesive layer 5 and the sealant layer 4 by a coextrusion method on a laminated body in which the base material layer 1/adhesive layer 2/metal layer 3 are laminated in order, the base material layer 1/adhesive layer 2/metal A packaging material for a battery was manufactured, which was composed of a laminate in which Layer 3/adhesive layer 5/sealant layer 4 were laminated in order. The specific manufacturing conditions of the battery packaging material are as follows.

In Examples 1-5 and Comparative Example 1, the biaxially stretched nylon film (thickness 15 μm) constituting the base material layer 1 and the aluminum foil (aluminum alloy) or stainless steel foil (each 35 μm) constituting the metal layer 2 were formed. ) Was used. Each of the biaxially stretched nylon films constituting the base material layer 1 is blended with ethylenebisstearic acid amide or ethylenebisoleic acid amide having the content shown in Table 1 as a water repellent. In addition, aluminum foil and stainless steel foil are roll-coated with a treatment liquid consisting of a phenol resin, a chromium fluoride compound (trivalent), and phosphoric acid so that the amount of chromium applied is 10 mg/m ² (dry weight). Was applied to both sides of the metal layer by the method and baked for 20 seconds under the condition that the film temperature was 180° C. or higher to perform chemical conversion treatment.

First, a laminated body in which the base material layer 1/adhesive layer 2/metal layer 3 were laminated in order was produced. Specifically, on one surface (corona-treated surface) of the base material layer 1, an adhesive layer 2 composed of a two-component urethane adhesive composed of a polyester-based main agent and an isocyanate-based curing agent is formed to have a thickness of 3 μm. Was laminated with the metal layer 3 by a dry lamination method to prepare a laminate in which the base material layer 1/adhesive layer 2/metal layer 3 were laminated in this order.

Next, as shown in Table 1, acid-modified polypropylene resin [unsaturated carboxylic acid graft-modified random polypropylene graft-modified with unsaturated carboxylic acid (acid-modified PP)] or acid-modified polyethylene resin constituting the adhesive layer 5 [ Unsaturated carboxylic acid graft-modified random polyethylene graft-modified with unsaturated carboxylic acid (acid-modified PE)] and polypropylene (random copolymer (PP)] or polyethylene (PE) constituting the sealant layer 4 are melted to form the above-mentioned laminate. It coextruded on the surface of the metal layer 3 of the body to laminate an adhesive layer 5 having a thickness of 20 μm and a sealant layer 4 having a thickness of 15 μm. As described above, a laminated body in which the base material layer 1/adhesive layer 2/metal layer 3/adhesive layer 5/sealant layer 4 were laminated in order was obtained. The obtained laminated body was once cooled, then heated to 180° C., and kept at that temperature for 1 minute to be heat-treated to obtain a battery packaging material.

<Measurement of the amount of water repellent that bleeds out to the surface of the base material layer by a treatment imitating a baking process during the production of battery cells>
The battery packaging material obtained in Examples 1-5 and Comparative Example 1 was left standing in a constant temperature bath at 100° C. for 24 hours to imitate the baking step at 100° C. in the production of battery cells, and the base material layer The surface (A4 size: 210 mm×297 mm) is washed with 30 ml of methanol, and the washed methanol is volatilized and dried by nitrogen blowing. Next, 1.5 ml of methanol was added to the dry solids and redissolved, and GC-MS (QP2010 manufactured by Shimadzu Corporation, ionization method: electron impact ionization method (EI method), detector: quadrupole detector, The amount of the water repellent agent (ethylenebisstearic acid amide or ethylenebisoleic acid amide) was measured with a column: Inert Cap 5MS. The results are shown in Table 1 (amount of surface bleed). The detection limit of the water repellent is 30 μg/A4 size.

<Printability evaluation>
With respect to the battery packaging materials of Examples 1-5 and Comparative Example 1 which were subjected to the above-mentioned baking process, a pattern was printed by pad printing on the surface of the base material layer. The pad printer used was SPACE PAD 6GX manufactured by Mishima Co., Ltd., and the ink used was UV ink PJU-A black manufactured by Navitas Co., Ltd. Further, the ink was cured by irradiating UV with a handy UV lamp SUV-4 manufactured by As One at an ultraviolet wavelength of 254 nm from a distance of 10 cm for 30 seconds. The printed surface after curing is observed with an optical microscope, and if there is no print defect within the visually recognizable range, it is "5", and if the print defect is more than 10% of the entire print pattern, it is "1". The middle was evaluated in the order of "2", "3", "4" from the evaluation side of "1". The printability was measured in an environment of 24° C. and a relative humidity of 50%. The results are shown in Table 1.

< Wetability evaluation>
Regarding the battery packaging materials of Examples 1-5 and Comparative Example 1 which were subjected to the above-mentioned baking process, a packaging material outer packaging material for a battery using a wetting reagent conforming to the JIS standard for the purpose of comparative verification of printing suitability. The wetting tension of the base material surface was evaluated . The test method was based on "JIS K6768 plastic-film and sheet-wet tension test method". Using a liquid mixture for wetting tension test manufactured by Nacalai Tesque, a reagent impregnated in spherical absorbent cotton is linearly applied on the base material surface of the packaging material for the battery by about 5 cm, and after 2 seconds, the liquid film is formed. judged by whether break, the wetting tension of not torn was unexpected Re sex of the substrate. The wet tension was measured at 24° C. in an environment with a relative humidity of 50%. The results are shown in Table 1.

In Table 1, EBS means ethylenebisstearic acid amide and EBO means ethylenebisoleic acid amide.

As shown in Table 1, in Examples 1-5 using ethylenebisstearic acid amide as a water repellent for nylon forming the base material layer, surface bleeding of the water repellent was suppressed, and ink of pad printing It had excellent printing characteristics. In particular, Example 1-2 was very excellent. On the other hand, in Comparative Example 1 in which ethylene bisoleic acid amide was used as the water repellent for nylon forming the base material layer, the water repellent was bleed out in a large amount, and the printing characteristics of the ink by pad printing were poor. The moldability of all the battery packaging materials was good.

1 Base Material Layer 2 Adhesive Layer 3 Metal Layer 4 Sealant Layer 5 Adhesive Layer

Claims (9)

At least a base material layer, a metal layer, and a sealant layer consisting of a laminated body sequentially laminated,
The base material layer is formed of a polyamide resin containing ethylenebisstearic acid amide ,
The content of the ethylenebisstearic acid amide in the polyamide resin is 200 ppm or more and 400 ppm or less,
A packaging material for a battery, wherein the wetting tension of the surface of the base material layer is 32 mN/m or more and 45 mN/m or less . The packaging material for a battery according to claim 1, which is used by printing ink on at least a part of the surface of the base material layer. The battery packaging material according to claim 1, wherein ink is printed on at least a part of the surface of the base material layer. The amount of ethylenebisstearic acid amide present on the surface of the base material layer within a range of 210 mm×297 mm is 30 μg or less after leaving the battery packaging material in a constant temperature bath at 100° C. for 24 hours. The packaging material for a battery according to any one of 1 to 3. The polyamide resin is a biaxially oriented nylon, packaging material for battery according to any one of claims 1-4. Battery packaging material according to any one of the adhesive layer are laminated, claims 1-5 between said metal layer and said base layer. The adhesive layer between the metal layer and the sealant layer are laminated packaging material for battery according to any one of claims 1-6. Wherein the metal layer is formed of aluminum foil or stainless steel foil, a battery packaging material according to any of claims 1-7. At least a positive electrode, a negative electrode, and a battery device having an electrolyte is housed in the battery packaging the material according to any one of claims 1-8, battery.