JP5626392B2 - Battery packaging materials - Google Patents

Description

  The present invention relates to a battery packaging material that can ensure safety even when the pressure or temperature in the battery continuously increases. More specifically, the present invention does not open until a set temperature determined between 140 and 160 ° C. is reached, the battery element can be maintained in a sealed state, and when the set temperature is reached, the battery element is quickly opened. The present invention also relates to a battery packaging material that can be gently opened to suppress excessive expansion of the battery packaging material and runaway battery reaction.

  Conventionally, various types of batteries have been developed. In any battery, a packaging material is an indispensable member for sealing battery elements such as electrodes and electrolytes. Conventionally, metal packaging materials have been widely used as battery packaging, but in recent years, with the increasing performance of electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, etc., batteries are required to have various shapes. At the same time, there is a demand for reduction in thickness and weight. However, metal battery packaging materials that have been widely used in the past have the disadvantages that it is difficult to follow the diversification of shapes and that there is a limit to weight reduction.

  Therefore, in recent years, as a battery packaging material that can be easily processed into various shapes and can be reduced in thickness and weight, a film-like laminate in which a base layer / adhesive layer / metal layer / sealant layer are sequentially laminated. Has been proposed (see, for example, Patent Document 1). Such a film-shaped battery packaging material is formed so that the battery element can be sealed by causing the sealant layers to face each other and heat-sealing the peripheral portion by heat sealing.

  On the other hand, depending on the type of electrolyte, the battery may generate a combustible gas and the pressure may increase. For example, when the battery is exposed to a high temperature, the organic solvent used in the electrolytic solution may be decomposed to generate a combustible gas and cause an increase in pressure. In addition, the battery may continuously increase in temperature due to charging due to overvoltage or discharging due to excessive current, causing battery reaction to runaway.

  In a battery using a film-like battery packaging material, such an increase in the pressure or temperature in the battery may cause the battery packaging material to be cleaved and cause ignition due to ejection of combustible gas. Further, if the pressure or temperature rises continuously in the battery and the battery reaction runs out of control when the battery packaging material is excessively expanded, the battery may explode.

  Conventionally, as a packaging material for a battery that can suppress the tearing of the heat seal part and the break before the heat seal part even when the pressure in the battery rises continuously, the sealant layer or adjacent thereto It has been reported that one of the adhesive resin layers has a cleavage inducing portion in which the stress at the time of cleavage is smaller than the stress at the time of cleavage of the fused surface between the sealant layers (see Patent Document 2). However, Patent Document 2 is not designed to be opened gently when the pressure or temperature in the battery has been continuously increased. In fact, in Patent Document 2, when a strong stress is applied, delamination in which cleavage proceeds between layers having adhesiveness, or cohesive failure in which cracks progress in an adhesive layer occurs. Designed to be If the battery is opened by delamination or cohesive failure when the pressure or temperature in the battery rises, there is a concern that the risk of ignition, explosion, or the like may increase due to a sudden ejection of combustible gas.

  Therefore, the battery packaging material is not cleaved until it reaches about 140 to 160 ° C. in order to ensure safety when the pressure or temperature rise in the battery continuously proceeds, and the battery element By maintaining the sealed state, the gas in the battery packaging material is gradually opened by gradually opening the gas when the temperature reaches about 140 to 160 ° C., while suppressing the ignition due to the sudden ejection of the combustible gas. It is required to be designed to release.

  In addition, because the temperature that should be induced to open from the maintenance of the battery packaging material varies depending on the type and use of the battery, the battery packaging material is designed to have a sealing property and an opening property depending on the battery to be applied. There is a need to. For example, if there is a battery that is required to be induced from a sealed state to an opened state when reaching 140 ° C., there is a battery that is required to be induced from the sealed state to the opened state when reaching 160 ° C. Therefore, in the prior art, the current situation is that the battery packaging material must be individually designed according to the temperature to be guided from the maintenance of the sealing to the opening, and the setting determined between 140 and 160 ° C. Regarding battery packaging materials that are induced to open from maintaining a sealed state at a temperature, a common design guideline that does not depend on the difference in the set temperature is not disclosed.

JP 2001-202927 A JP 2012-203982 A

  An object of this invention is to provide the battery packaging material which can ensure safety | security even when the raise in the pressure in a battery and temperature progresses continuously. More specifically, according to the present invention, the battery element can be maintained in a sealed state without being cleaved until reaching a set temperature determined between 140 and 160 ° C., and when the set temperature is reached. An object of the present invention is to provide a battery packaging material that can be opened quickly and gently, and that can suppress excessive expansion of the battery packaging material and runaway battery reaction.

  The inventors of the present invention made extensive studies in order to solve the above-mentioned problems, and consisted of at least a base material layer, an adhesive layer, a metal layer, and a sealant layer in this order, and the sealant layer is a metal layer. A first sealant layer containing acid-modified polyolefin located on the side, a second sealant layer laminated on the first sealant layer and located in the innermost layer and containing polyolefin, and the first sealant layer and the first sealant layer The battery packaging material in which the melting points of the two sealant layers satisfy a predetermined relationship is the metal layer until the temperature reaches T ° C. when the temperature is raised to a set temperature T ° C. determined between 140 ° C. and 160 ° C. At least a part of the interface between the first sealant layer and the first sealant layer is peeled off, but the battery element can be kept sealed by the first sealant layer and the second sealant layer, and promptly before the temperature reaches T ° C. It found that can open gently cause fine cleavage of pinholes in the sealant layer of the release portion from the metal layer. The present invention has been completed by further studies based on such knowledge.

That is, this invention provides the invention of the aspect hung up below.
Item 1. When the temperature is raised to a set temperature T ° C determined between 140 ° C and 160 ° C, the packaging material is not opened until the temperature reaches T ° C. After reaching T ° C, the packaging material is opened quickly. A battery packaging material used for a battery,
It consists of a laminate having at least a base material layer, an adhesive layer, a metal layer, and a sealant layer in this order,
The sealant layer is located on the metal layer side, and has a first sealant layer containing acid-modified polyolefin, and a second sealant layer containing polyolefin on the innermost layer laminated on the first sealant layer,
The first sealant layer and the second sealant layer are represented by the following formulas (1) and (2):
−10 ≦ T ₁ −T ≦ −5 (1)
−5 ≦ T ₂ −T ≦ 5 (2)
T ₁ : Melting point (° C.) of the first sealant layer
T ₂ : Melting point (° C.) of the second sealant layer
A battery packaging material characterized by satisfying
Item 2. Item 2. The battery packaging material according to Item 1, wherein the acidic polyolefin contained in the first sealant layer contains at least propylene as a constituent monomer.
Item 3. Item 3. The battery packaging material according to Item 1 or 2, wherein the polyolefin contained in the second sealant layer contains at least propylene as a constituent monomer.
Item 4. Item 4. The battery packaging material according to any one of Items 1 to 3, wherein the first sealant layer has a thickness of 5 to 40 µm, and the second sealant layer has a thickness of 5 to 40 µm.
Item 5. Item 5. The battery packaging material according to any one of Items 1 to 4, wherein the metal layer is an aluminum foil.
Item 6. Item 6. The battery packaging material according to any one of Items 1 to 5, wherein at least one of the first sealant layer and the second sealant layer contains a slip agent.
Item 7. Item 7. A battery in which a battery element including at least a positive electrode, a negative electrode, and an electrolyte is accommodated in the battery packaging material according to any one of Items 1 to 6.
Item 8. A method for screening a resin component used in a sealant layer formed on a battery packaging material,
When the battery packaging material is heated to a set temperature T ° C. determined between 140 ° C. and 160 ° C., the packaging material is not opened until the temperature reaches T ° C. After the temperature reaches T ° C., the packaging material is quickly opened. Used for batteries set to open,
The battery packaging material comprises a laminate having a base layer, an adhesive layer, a metal layer, and a sealant layer in this order, and the sealant layer includes a first sealant layer located on the metal layer side, and the first sealant layer. A second sealant layer that is laminated on the sealant layer and located in the innermost layer;
At least acid-modified polyolefin is selected as the resin component forming the first sealant layer, at least polyolefin is selected as the resin component forming the second sealant layer, and the first sealant layer and the second sealant layer are represented by the following formula ( 1) and (2)
−10 ≦ T ₁ −T ≦ −5 (1)
−5 ≦ T ₂ −T ≦ 5 (2)
T ₁ : Melting point (° C.) of the first sealant layer
T ₂ : Melting point (° C.) of the second sealant layer
The screening method is characterized in that the resin component forming the first sealant layer and the second sealant layer is selected so as to satisfy the above.

  The battery packaging material of the present invention comprises a laminate having a base material layer, an adhesive layer, a metal layer, and a sealant layer in this order. The sealant layer is located on the metal layer side and includes a first acid-modified polyolefin. A sealant layer and a second sealant layer that is laminated on the first sealant layer and is positioned as the innermost layer and containing polyolefin, and the melting points of the first sealant layer and the second sealant layer satisfy a predetermined relationship. It is characterized by that. When the battery packaging material of the present invention is heated to a set temperature T ° C. determined between 140 ° C. and 160 ° C. by adopting such a specific configuration, the metal packaging material until the temperature reaches T ° C. Although at least a part of the interface between the layer and the first sealant layer is peeled off, the battery element can be maintained in a sealed state by forming the sealant layer in a bag shape. In addition, the battery packaging material of the present invention can be opened under mild conditions by causing minute cracks such as pinholes in the sealant layer separated from the metal layer immediately after reaching the set temperature T ° C. Can be in a state. Thus, the battery packaging material of the present invention does not cleave until reaching a set temperature determined between 140 and 160 ° C., can maintain the battery element in a sealed state, and reaches the set temperature. Can be opened quickly and gently, even if the pressure or temperature rises continuously in the battery, excessive expansion of the battery packaging material and runaway battery reaction can be suppressed. Is secured.

It is a figure which shows an example of the cross-section of the packaging material for batteries of this invention. A state (A) in which two battery packaging materials of the present invention are heat-sealed to form a sealed space, and when the temperature is raised to a set temperature T ° C. determined between 140 ° C. and 160 ° C., the set temperature T ° C. It is sectional drawing (the left end is heat-sealed and the right side part is abbreviate | omitted) of one side about the state (B) before reaching | attainment, and the state (C) after reaching preset temperature T degreeC. It is a schematic diagram which shows the cleaved state which arises when two conventional packaging materials for batteries are heat-sealed to form a sealed space and heated to a set temperature T ° C determined between 140 ° C and 160 ° C.

A. Battery packaging material The battery packaging material of the present invention does not open until the temperature reaches T ° C. when the temperature is raised to a set temperature T ° C. determined between 140 ° C. and 160 ° C., and reaches T ° C. The latter is a battery packaging material used for a battery set so that the packaging material can be quickly opened; it comprises at least a laminate having a base layer, an adhesive layer, a metal layer, and a sealant layer in this order. The sealant layer is located on the metal layer side, and includes a first sealant layer containing acid-modified polyolefin, and a second sealant layer laminated on the first sealant layer and located in the innermost layer and containing polyolefin; In addition, the melting points of the first sealant layer and the second sealant layer satisfy a predetermined relationship. Hereinafter, the battery packaging material of the present invention will be described in detail.

1. As shown in FIG. 1, the battery packaging material comprises a laminate having at least a base material layer 1, an adhesive layer 2, a metal layer 3, and a sealant layer 4 in this order, and the sealant. The layer 4 has the 1st sealant layer 4a located in the metal layer side, and the 2nd sealant layer 4b laminated | stacked on the said 1st sealant layer and located in the innermost layer. That is, the battery packaging material of the present invention is composed of a laminate having the base layer 1, the adhesive layer 2, the metal layer 3, the first sealant layer 4a, and the second sealant layer 4b in this order. It becomes the outermost layer, and the second sealant layer 4b becomes the innermost layer. When assembling the battery, the second sealant layers 4b located on the periphery of the battery element are brought into contact with each other and thermally welded to seal the battery element, thereby sealing the battery element.

2. Opening mechanism of battery packaging material The battery packaging material of the present invention has a sealing property until reaching a set temperature T ° C defined between 140 ° C and 160 ° C, and a quick and gentle after reaching the set temperature T ° C. It has a good openability. An example of the opening mechanism of the battery packaging material of the present invention will be described with reference to FIG. FIG. 2A shows a cross-sectional view of one side when a battery element is sealed in two battery packaging materials of the present invention. In FIG. 2A, the edges of the two sealant layers 4 of the battery packaging material are heat-sealed to form a sealed space. Although the battery element is accommodated in the sealed space, the battery element is omitted in FIG. When the temperature is raised from the state of A in FIG. 2 to a set temperature T ° C. determined between 140 and 160 ° C., at least a part of the interface between the metal layer 3 and the sealant layer 4 is formed as shown in B of FIG. Although peeled off, the sealant layer 4 is formed in a bag shape (inner bag shape), and the battery element is kept sealed. When the temperature reaches the set temperature T ° C., the state quickly shifts to the state shown in FIG. 2C, and fine cracks (symbol 10 in FIG. 2) are generated in the region of the sealant layer 4 peeled from the metal layer 3. Will be opened under mild conditions.

  On the other hand, conventional battery packaging materials are opened quickly after reaching the set temperature T.degree. C., without being opened quickly, or ignited or exploding, or immediately before or after reaching the set temperature T.degree. There is a case where the state rapidly changes and a flammable gas or an electrolytic solution is suddenly ejected. This abrupt transition from the sealed state to the unsealed state is caused by the transition to any one of interface peeling, cohesive peeling, and delamination. Here, interfacial peeling refers to a peeling state in which cleavage proceeds at the heat seal interface between the sealant layers, and an example of the schematic diagram is shown in FIG. Moreover, cohesive peeling refers to the peeling state in which the cleavage proceeds inside the sealant layer, and an example of the schematic diagram is shown in FIG. In addition, delamination refers to a delamination state in which cleavage progresses between layers (layers within a sealant layer or between a metal layer and a sealant layer) after the sealant layer is broken, and an example of a schematic diagram thereof Is shown in FIG. The “root break” means that the sealant layer is broken at the inner edge of the heat seal portion. Since the battery packaging material of the present invention does not cause such interfacial peeling, cohesive peeling, or delamination to shift to an abrupt opening state, the battery packaging material in the battery has a higher capacity than conventional battery packaging materials. Excellent safety when pressure and temperature rise continuously.

3. Composition of each layer forming base material for battery [base material layer 1]
In the battery packaging material of the present invention, the base material layer 1 is a layer forming the outermost layer. The material for forming the base material layer 1 is not particularly limited as long as it has insulating properties. Examples of the material for forming the base material layer 1 include polyester, polyamide, epoxy, acrylic, fluororesin, polyurethane, silicon resin, phenol, polyetherimide, polyimide, and a mixture or copolymer thereof.

  Specific examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, copolymerized polyester mainly composed of ethylene terephthalate, and repeating units of butylene terephthalate. Copolyester etc. mainly composed of The copolymer polyester mainly composed of ethylene terephthalate is a copolymer polyester that polymerizes with ethylene isophthalate mainly composed of ethylene terephthalate (hereinafter, polyethylene (terephthalate / isophthalate)). Abbreviated), polyethylene (terephthalate / isophthalate), polyethylene (terephthalate / adipate), polyethylene (terephthalate / sodium sulfoisophthalate), polyethylene (terephthalate / sodium isophthalate), polyethylene (terephthalate / phenyl-dicarboxylate) And polyethylene (terephthalate / decanedicarboxylate). In addition, as a copolymer polyester mainly composed of butylene terephthalate as a repeating unit, specifically, a copolymer polyester that polymerizes with butylene isophthalate having butylene terephthalate as a repeating unit (hereinafter referred to as polybutylene (terephthalate / isophthalate)). For example), polybutylene (terephthalate / adipate), polybutylene (terephthalate / sebacate), polybutylene (terephthalate / decanedicarboxylate), polybutylene naphthalate and the like. These polyesters may be used individually by 1 type, and may be used in combination of 2 or more type. Polyester has the advantage of being excellent in electrolytic solution resistance and less likely to cause whitening due to the adhesion of the electrolytic solution, and is suitably used as a material for forming the base material layer 1.

  Specific examples of the polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and a copolymer of nylon 6 and nylon 6,6; terephthalic acid and / or Or hexamethylenediamine-isophthalic acid-terephthalic acid copolymerized polyamide, polymer, such as nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid) containing structural units derived from isophthalic acid Polyamides containing aromatics such as taxylylene adipamide (MXD6); Alicyclic polyamides such as polyaminomethylcyclohexyl adipamide (PACM6); and isocyanate components such as lactam components and 4,4′-diphenylmethane-diisocyanate Copolymerized polyamide, Polyester amide copolymer and polyether ester amide copolymer is a copolymer of polymerized polyamide and polyester and polyalkylene ether glycol; copolymers thereof, and the like. These polyamides may be used individually by 1 type, and may be used in combination of 2 or more type. The stretched polyamide film is excellent in 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.

  The base material layer 1 may be formed of a uniaxially or biaxially stretched resin film, or may be formed of an unstretched resin film. Among them, a uniaxially or biaxially stretched resin film, in particular, a biaxially stretched resin film has improved heat resistance by orientation crystallization, and thus is suitably used as the base material layer 1.

  Among these, as a resin film which forms the base material layer 1, Preferably nylon and polyester, More preferably, biaxially stretched nylon, biaxially stretched polyester, Most preferably, biaxially stretched nylon is mentioned.

  The base material layer 1 can also be laminated with resin films of different materials in order to improve pinhole resistance and insulation when used as a battery package. Specific examples include a multilayer structure in which a polyester film and a nylon film are laminated, and a multilayer structure in which a biaxially stretched polyester and a biaxially stretched nylon are laminated. When making the base material layer 1 into a multilayer structure, each resin film may be adhere | attached through an adhesive agent, and may be laminated | stacked directly without an adhesive agent. In the case of bonding without using an adhesive, for example, a method of bonding in a hot melt state such as a co-extrusion method, a sand lamination method, or a thermal laminating method can be mentioned. Moreover, when making it adhere | attach through an adhesive agent, the adhesive agent to be used may be a two-component curable adhesive, or a one-component curable adhesive. Further, the bonding mechanism of the adhesive is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a heat melting type, a hot pressure type, an electron beam curing type such as UV and EB, and the like. As an adhesive component, polyester resin, polyether resin, polyurethane resin, epoxy resin, phenol resin resin, polyamide resin, polyolefin resin, polyvinyl acetate resin, cellulose resin, (meth) acrylic resin Resins, polyimide resins, amino resins, rubbers, and silicon resins can be used.

  The base material layer 1 may be reduced in friction in order to improve moldability. In the case of reducing the friction of the base material layer 1, the friction coefficient of the surface is not particularly limited, but for example, 1.0 or less can be mentioned. In order to reduce the friction of the base material layer 1, for example, mat treatment, formation of a thin film layer of a slip agent, a combination thereof, and the like can be given.

  As the matting treatment, a matting agent is added to the base material layer 1 in advance to form irregularities on the surface, a transfer method by heating or pressurizing with an embossing roll, a surface is mechanically dry or wet blasting or filed. The method of ruining is mentioned. Examples of the matting agent include fine particles having a particle size of about 0.5 nm to 5 μm. The material of the matting agent is not particularly limited, and examples thereof include metals, metal oxides, inorganic substances, and organic substances. The shape of the matting agent is not particularly limited, and examples thereof include a spherical shape, a fiber shape, a plate shape, an indeterminate shape, and a balloon shape. As a matting agent, specifically, talc, silica, graphite, kaolin, montmorilloid, montmorillonite, synthetic mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, oxidation Aluminum, neodymium oxide, antimony oxide, titanium oxide, cerium oxide, calcium sulfate, barium sulfate, calcium carbonate, calcium silicate, lithium carbonate, calcium benzoate, calcium oxalate, magnesium stearate, alumina, carbon black, carbon nanotubes , High melting point nylon, crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, nickel and the like. These matting agents may be used individually by 1 type, and may be used in combination of 2 or more type. Among these matting agents, silica, barium sulfate, and titanium oxide are preferable from the viewpoint of dispersion stability and cost. The matting agent may be subjected to various surface treatments such as insulation treatment and high dispersibility treatment on the surface noodles.

  The slip agent thin film layer can be formed by depositing a slip agent on the surface of the base material layer 1 by bleeding out to form a thin layer, or by laminating the slip agent on the base material layer 1. Although it does not restrict | limit especially as a slip agent, For example, what was illustrated by the below-mentioned 1st sealant layer is mentioned.

  As for the thickness of the base material layer 1, 10-50 micrometers is mentioned, for example, Preferably 15-30 micrometers is mentioned.

[Adhesive layer 2]
In the battery packaging material of the present invention, the adhesive layer 2 is a layer provided for bonding the base material layer 1 and the metal layer 3 together.

  The adhesive layer 2 is formed of an adhesive capable of adhering the base material layer 1 and the metal layer 3. The adhesive used for forming the adhesive layer 2 may be a two-component curable adhesive or a one-component curable adhesive. Further, the adhesive 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, and a hot pressure type.

  Specific examples of the resin component of the adhesive that can be used to form the adhesive layer 2 include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, polycarbonate, and copolyester. Resin; Polyether adhesive; Polyurethane adhesive; Epoxy resin; Phenol resin resin; Polyamide resin such as nylon 6, nylon 66, nylon 12, copolymer polyamide; polyolefin, acid-modified polyolefin, metal-modified polyolefin, etc. Polyolefin resin; polyvinyl acetate resin; cellulose adhesive; (meth) acrylic resin; polyimide resin; urea resin, melamine resin and other amino resins; chloroprene rubber, nitrile rubber, styrene - rubbers such as butadiene rubber, silicone resin; fluorinated ethylene propylene copolymer, and the like. These adhesive components may be used individually by 1 type, and may be used in combination of 2 or more type. The combination mode of two or more kinds of adhesive components is not particularly limited. 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 thereof include a mixed resin of polyester and acid-modified polyolefin, and a mixed resin of polyester and metal-modified polyolefin. Among these, extensibility, durability under high humidity conditions, anti-hypertensive action, thermal deterioration-preventing action during heat sealing, etc. are excellent, and a decrease in the lamination strength between the base material layer 1 and the metal layer 2 is suppressed. From the viewpoint of effectively suppressing the occurrence of delamination, a polyurethane two-component curable adhesive; polyamide, polyester, or a blended resin of these with a modified polyolefin is preferable.

  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 between the base material layer 1 and the metal layer 3, the adhesive component disposed on the base material layer 1 side is used as the base material layer 1. It is preferable to select a resin having excellent adhesion to the metal layer 3 and to select an adhesive component having excellent adhesion 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. And a resin containing a copolyester.

  About the thickness of the contact bonding layer 2, 2-50 micrometers, for example, Preferably 3-25 micrometers is mentioned.

[Metal layer 3]
In the battery packaging material of the present invention, the metal layer 3 is a layer that functions as a barrier layer for preventing the penetration of water vapor, oxygen, light, etc. into the battery, in addition to improving the strength of the packaging material. Specific examples of the metal forming the metal layer 3 include metal foils such as aluminum, stainless steel, and titanium. Among these, aluminum is preferably used. In order to prevent wrinkles and pinholes during the production of the packaging material, soft aluminum such as annealed aluminum (JIS A8021P-O) or (JIS A8079P-O) is used as the metal layer 3 in the present invention. Is preferred.

  About thickness of the metal layer 3, 10-200 micrometers is preferable, for example, Preferably it is 20-100 micrometers.

  In addition, 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 side, and more preferably both surfaces for stabilization of adhesion, prevention of dissolution and corrosion, and the like. Here, the chemical conversion treatment is a treatment for forming an acid-resistant film on the surface of the metal layer 3. Chemical conversion treatment is, for example, chromate chromate treatment using a chromic acid compound such as chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium biphosphate, chromic acetyl acetate, chromium chloride, potassium sulfate chromium, etc. ; Phosphoric acid chromate treatment using phosphoric acid compounds such as sodium phosphate, potassium phosphate, ammonium phosphate, polyphosphoric acid; aminated phenol heavy consisting of repeating units represented by the following general formulas (1) to (4) Examples thereof include chromate treatment using a coalescence.

In general 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 represent 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, C1-C4 linear or branched alkyl groups, such as a tert- butyl group, are mentioned. 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, 3- A linear or branched chain having 1 to 4 carbon atoms substituted with one hydroxy group such as hydroxypropyl group, 1-hydroxybutyl group, 2-hydroxybutyl group, 3-hydroxybutyl group, 4-hydroxybutyl group An alkyl group is mentioned. be able to. In the general formulas (1) to (4), X is preferably any one of a hydrogen atom, a hydroxyl group, and a droxyalkyl group. The number average molecular weight of the aminated phenol polymer composed of 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.

  In addition, as a chemical conversion treatment method for imparting corrosion resistance to the metal layer 3, a metal oxide such as aluminum oxide, titanium oxide, cerium oxide, tin oxide, or barium sulfate fine particles dispersed in phosphoric acid is coated. A method of forming a corrosion-resistant layer on the surface of the metal layer by performing a baking treatment at 150 ° C. or higher can be mentioned. A resin layer obtained by crosslinking a cationic polymer with a crosslinking agent may be formed on the corrosion-resistant treatment 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 on an acrylic main skeleton, polyallylamine, or Examples thereof include aminophenols and derivatives thereof. These cationic polymers may be used individually by 1 type, and may be used in combination of 2 or more type. Examples of the crosslinking agent include compounds having at least one functional group selected from the group consisting of isocyanate groups, glycidyl groups, carboxyl groups, and oxazoline groups, silane coupling agents, and the like. These crosslinking agents may be used alone or in combination of two or more.

  These chemical conversion treatments may be performed alone or in combination of two or more chemical conversion treatments. Furthermore, these chemical conversion treatments may be carried out using one kind of compound alone, or may be carried out using a combination of two or more kinds of compounds. Among these, chromic acid chromate treatment is preferable, and chromate treatment in which a chromic acid compound, a phosphoric acid compound, and the aminated phenol polymer are combined is more preferable.

The amount of the acid-resistant film to be formed on the surface of the metal layer 3 in the chemical conversion treatment is not particularly limited. For example, the chromate treatment may be performed by combining a chromic acid compound, a phosphoric acid compound, and the aminated phenol polymer. For example, the chromic acid compound is about 0.5 to about 50 mg, preferably about 1.0 to about 40 mg in terms of chromium, 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. Is about 1.0 to about 40 mg, and the aminated phenol polymer is contained in an amount of about 1 to about 200 mg, preferably about 5.0 to 150 mg.

  In the chemical conversion treatment, a solution containing a compound used for forming an acid-resistant film is applied to the surface of the metal layer by a bar coating method, a roll coating method, a gravure coating method, an immersion method or the like, and then the temperature of the metal layer is 70. It is carried out by heating to about 200 ° C. In addition, before the chemical conversion treatment is performed on the metal layer 3, the metal layer 3 may be 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 in advance. By performing the degreasing treatment in this way, it becomes possible to more efficiently perform the chemical conversion treatment on the surface of the metal layer 3.

[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 when the battery is assembled. The sealant layer 4 has a layer structure including a first sealant layer located on the metal layer side and a second sealant layer laminated on the first sealant layer and located in the innermost layer.

(First sealant layer)
The first sealant layer is a layer containing acid-modified polyolefin and located on the metal layer side. The acid-modified polyolefin used for forming the first sealant layer is a polymer modified by graft polymerization of polyolefin with an unsaturated carboxylic acid. Specific examples of the acid-modified polyolefin include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; homopolypropylene, block copolymer of polypropylene (for example, block copolymer of propylene and ethylene) ), A random or amorphous polypropylene copolymer (for example, a random copolymer of propylene and ethylene), and a terpolymer of ethylene-butene-propylene. Among these polyolefins, from the viewpoint of heat resistance, polyolefins having at least propylene as a constituent monomer are preferable, and ethylene-butene-propylene terpolymers and propylene-ethylene random copolymers are more preferable. Examples of the unsaturated carboxylic acid used for modification include maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, itaconic anhydride and the like. Among these unsaturated carboxylic acids, maleic acid and maleic anhydride are preferable. These acid-modified polyolefins may be used individually by 1 type, and may be used in combination of 2 or more type.

  The first sealant layer may be formed only from the acid-modified polyolefin as long as it has a melting point described later, and may contain a resin component other than the acid-modified polyolefin as necessary. When the resin component other than the acid-modified polyolefin is contained in the first sealant layer, the content of the acid-modified polyolefin in the first sealant layer is not particularly limited as long as the effect of the present invention is not hindered. %, Preferably 30 to 90% by mass, and further 50 to 80% by mass.

  In the first sealant layer, in addition to the acid-modified polyolefin, examples of the resin component that can be contained as necessary include polyolefin.

  The polyolefin may have an acyclic structure or a cyclic structure. Specific examples of the acyclic polyolefin include polyethylene such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; homopolypropylene, block copolymer of polypropylene (for example, block copolymer of propylene and ethylene) And crystalline or amorphous polypropylene such as a random copolymer of polypropylene (for example, a random copolymer of propylene and ethylene); a terpolymer of ethylene-butene-propylene, and the like. The cyclic polyolefin is a copolymer of an olefin and a cyclic monomer. Examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, And isoprene. Examples of the cyclic monomer that is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; specifically, cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. These polyolefins may be used individually by 1 type, and may be used in combination of 2 or more type.

  Among these polyolefins, those having characteristics as an elastomer (that is, polyolefin-based elastomers), particularly propylene-based elastomers, are preferable from the viewpoints of improving adhesive strength after heat sealing, preventing delamination after heat sealing, and the like. . Examples of the propylene-based elastomer include polymers containing propylene and one or more α-olefins having 2 to 20 carbon atoms (excluding propylene) as constituent monomers, and the number of carbon atoms constituting the propylene-based elastomer is 2. Specific examples of the α-olefin of ˜20 (excluding propylene) include ethylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-octene, 1-decene, 1 -Dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene, 1-eicocene and the like. These ethylene-based elastomers may be used alone or in combination of two or more.

  When the resin component other than the acid-modified polyolefin is contained in the first sealant layer, the content of the resin component is appropriately set within a range that does not hinder the object of the present invention. For example, when the first sealant layer contains a propylene-based elastomer, the content of the propylene-based elastomer in the first sealant layer is usually 5 to 60% by mass, preferably 10 to 50% by mass, and more preferably 20 to 20%. 40 mass% is mentioned.

The first sealant layer is set so as to satisfy the following formula (1) in addition to containing the acid-modified polyolefin.
−10 ≦ T ₁ −T ≦ −5 (1)
T: Set temperature (° C) determined between 140 and 160 ° C
T ₁ : Melting point (° C.) of the first sealant layer

Thus, when the melting point T ₁ of the first sealant layer is set to a value lower than the set temperature T within a predetermined range, the first sealant layer is melted when the battery is exposed to a high temperature up to T ° C. The state changes, and at least a part of the sealant layer 4 can be peeled from the interface between the metal layer 3 and the sealant layer 4. Then, at least a part of the sealant layer 4 peeled from the metal layer 3 expands due to internal pressure and swells while maintaining a sealed state, and then the swelled sealant layer 4 is finely cleaved within 30 minutes after reaching T ° C. ( Pinhole or the like), and the gas inside the battery can be released gently.

Here, the melting point T ₁ of the first sealant layer, the melting point of the resin component constituting the first sealant layer JIS K6921-2: is a value measured by conforming to (ISO1873-2.2 95) DSC method . Further, when the first sealant layer is formed of a blend resin containing a plurality of resin components, the melting point T ₁ conforms to the blend resin according to JIS K6921-2 (ISO1873-2.2: 95). Then, the DSC method was used, the ratio of the peak area of the melting point corresponding to each resin component was calculated with the total peak area being 1, and the value obtained by multiplying the melting point corresponding to each resin component and the ratio of the peak area (melting point × area ratio) ) And the value calculated for each melting point (melting point × area ratio) is added.

  Since the melting point of the resin component is determined by the molecular weight, the type and ratio of the constituent monomer, etc., the acid-modified polyolefin to be blended in the first sealant layer and the other resin component blended as necessary are the above-mentioned of the first sealant layer. The molecular weight, the type and ratio of the constituent monomers, etc. are appropriately set so as to satisfy the melting point range.

  The first sealant layer may contain a slip agent as necessary. When the first sealant layer contains a slip agent, the moldability of the battery packaging material can be improved. Furthermore, in this invention, when a 1st sealant layer contains a slip agent, not only the moldability of a battery packaging material but insulation can be improved. Although the detailed mechanism by which the insulating property of the battery packaging material is enhanced by including the slip agent in the first sealant layer is not necessarily clear, for example, it can be considered as follows. That is, when the first sealant layer contains a slip agent, when an external force is applied to the first sealant layer, the molecular chains of the resin are likely to move in the first sealant layer, and cracks are less likely to occur. In particular, when the first sealant layer is formed of a plurality of types of resins, cracks are likely to occur at the interfaces existing between these resins. In this case, it is considered that the resin easily moves, so that cracks can be effectively suppressed when an external force is applied. By such a mechanism, it is considered that a decrease in insulation due to the occurrence of cracks in the first sealant layer is suppressed.

  The slip agent is not particularly limited, and known slip agents can be used. For example, fatty acid amides such as erucic acid amide, stearic acid amide, and oleic acid amide, metal soap, hydrophilic silicone, and acrylic grafted with silicone. And silicone grafted epoxy, silicone grafted polyether, silicone grafted polyester, block-type silicone acrylic copolymer, polyglycerol-modified silicone, paraffin and the like. These slip agents may be used individually by 1 type, and may be used in combination of 2 or more type. The content of the slip agent in the first sealant layer is not particularly limited, and is preferably about 0.01 to 0.2% by mass, more preferably from the viewpoint of improving the moldability and insulation of the electronic packaging material. Is about 0.1 to 0.15% by mass.

  Moreover, as thickness of a 1st sealant layer, 5-40 micrometers, for example, Preferably it is 10-35 micrometers, More preferably, 15-30 micrometers is mentioned.

(Second sealant layer)
The second sealant layer is a layer containing polyolefin, and is laminated on the first sealant layer and positioned as the innermost layer of the battery packaging material. The polyolefin used for forming the second sealant layer is not particularly limited as long as the melting point described below is satisfied, but examples thereof include low-density polyethylene, medium-density polyethylene, high-density polyethylene, and linear low-density polyethylene. Polyethylene; Crystalline or amorphous polypropylene such as homopolypropylene, polypropylene block copolymer (eg, propylene and ethylene block copolymer), polypropylene random copolymer (eg, propylene and ethylene random copolymer); ethylene-butene-propylene Terpolymers, and the like. Among these polyolefins, from the viewpoint of heat resistance, a polyolefin having at least propylene as a constituent monomer is preferable, more preferably a random copolymer of propylene-ethylene, a terpolymer of propylene-ethylene-butene, and a homopolymer of propylene. Can be mentioned. These polyolefins may be used individually by 1 type, and may be used in combination of 2 or more type.

  The second sealant layer may be formed of only a polyolefin as long as it has a melting point described later, and may contain a resin component other than the polyolefin as necessary. When the resin component other than the polyolefin is contained in the second sealant layer, the content of the polyolefin in the second sealant layer is not particularly limited as long as the effect of the present invention is not hindered, for example, 10 to 95% by mass, preferably 30-90 mass%, Furthermore, 50-80 mass% is mentioned.

  In addition to polyolefin in the second sealant layer, examples of the resin component that can be contained as needed include acid-modified polyolefin. Specific examples of the acid-modified polyolefin are the same as those exemplified in the column of the first sealant layer. When a resin component other than polyolefin is contained in the second sealant layer, the content of the resin component is appropriately set within a range that does not hinder the object of the present invention. For example, when the acid-modified polyolefin is contained in the second sealant layer, the content of the acid-modified polyolefin in the second sealant layer is usually 5 to 60% by mass, preferably 10 to 50% by mass, more preferably 20 to 20%. 40 mass% is mentioned.

The second sealant layer is set so as to satisfy the following formula (2) in addition to containing polyolefin.
−5 ≦ T ₂ −T ≦ 5 (2)
T: Set temperature (° C) determined between 140 and 160 ° C
T ₂ : Melting point (° C.) of the first sealant layer

In this way, the melting point T ₂ of the second sealant layer is set to be equal to or higher than the melting point T ₁ of the first sealant layer, and is set in the temperature range around 5 ° C. with the set temperature T, whereby the battery is set to the set temperature T ° C. The second sealant layer swells with an internal pressure even if at least part of the sealant layer 4 is peeled off from the interface between the metal layer 3 and the sealant layer 4 by being exposed to a high temperature until the first sealant layer is melted. However, it functions to maintain a sealed state, and after reaching the set temperature T ° C., it makes it possible to quickly cause fine cleaving (pinholes and the like) and to gently release the gas inside the battery. Further, if the melting point T ₂ of the second sealant layer is set in a temperature range exceeding 5 ° C. from the set temperature T, the heat seal itself becomes difficult, and even if the seal strength varies or reaches T ° C. There is a tendency that the sealant layer 4 cannot be opened quickly.

The method for calculating the melting point T ₂ of the second sealant layer is the same as that for the melting point T ₁ of the first sealant layer.

  Since the melting point of the resin component is determined by the molecular weight, the type and ratio of the constituent monomer, etc., the polyolefin compounded in the second sealant layer and the other resin component compounded as necessary are equal to the melting point of the second sealant layer. The molecular weight, the type and ratio of constituent monomers, etc. are appropriately set so as to satisfy the range.

  Similar to the first sealant layer, the second sealant layer may contain a slip agent as necessary. Moreover, the slip agent may be apply | coated on the surface on the opposite side to the 1st sealant layer of a 2nd sealant layer. When the second sealant layer contains a slip agent and when the slip agent is applied on the surface of the second sealant layer, the moldability of the battery packaging material can be improved.

Furthermore, in this invention, when a 2nd sealant layer contains a slip agent, not only the moldability of a battery packaging material but insulation can be improved. In the present invention, it is preferable that at least one of the first sealant layer and the second sealant layer contains a slip agent from the viewpoint of enhancing the insulating properties of the battery packaging material. Although the detailed mechanism by which the insulating property of the battery packaging material is enhanced by including the slip agent in the second sealant layer is not necessarily clear, it can be considered in the same manner as the first sealant layer. In particular, since the second sealant layer is located in the innermost layer of the battery packaging material, a large external force is easily applied during heat sealing. For this reason, when the above-mentioned slip agent is contained in the second sealant layer located in the innermost layer, the moldability and insulation of the battery packaging material can be improved more effectively. The kind and amount of slip agent contained in the second sealant layer can be the same as those of the first sealant layer. Moreover, when applying a slip agent on the surface of a 2nd sealant layer, the kind of slip agent can be made the same as that of a 1st sealant layer. The coating amount of the slip agent is not particularly limited, for example, 0.01 - 100 / m ² approximately, and preferably about 0.1 to 10 mg / m ^2.

  Moreover, as thickness of a 2nd sealant layer, 5-40 micrometers, Preferably it is 10-35 micrometers, More preferably, 15-30 micrometers is mentioned.

(Relationship between melting point of first sealant layer and second sealant layer)
The first sealant layer and the second sealant layer satisfy the relationship of 0 ≦ (T ₂ −T ₁ ) ≦ 15 by satisfying the above-described melting points.

(Thickness of sealant layer 4)
The thickness of the sealant layer 4 is determined based on the thickness of each of the first sealant layer and the second sealant layer, and is, for example, 10 to 80 μm, preferably 20 to 70 μm, and more preferably 30 to 60 μm. .

4). 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 in which layers having a predetermined composition are laminated is obtained. For example, the following method is exemplified. .

  First, a laminate in which the base material layer 1, the adhesive layer 2, and the metal layer 3 are laminated in order (hereinafter also referred to as “laminate A”) is formed. Specifically, the laminate A is formed by using a thermal laminating method, a sand laminating method, using an adhesive that forms the adhesive layer 2 on the base material 1 and the metal layer 3 whose surface is subjected to a chemical conversion treatment if necessary. It is performed by laminating by a method or a combination thereof.

  The laminate A is formed by the thermal laminating method. For example, a multilayer film in which the base material layer 1 and the adhesive layer 2 are laminated is prepared in advance, and the metal layer 3 is superimposed on the adhesive layer 2 and heated with a heating roll. It can be performed by thermocompression bonding with the adhesive layer 2 sandwiched between the layer 1 and the metal layer 3. The laminate A is formed by the thermal laminating method in which a multilayer film in which the metal layer 3 and the adhesive layer 2 are laminated is prepared in advance, and the base material layer 1 is superposed on the heated metal layer 3 and the adhesive layer 2. It may be performed by thermocompression bonding while sandwiching the adhesive layer 2 between the base material layer 1 and the metal layer 3.

  In addition, the multilayer film in which the base material layer 1 and the adhesive layer 2 prepared in advance in the thermal laminating method are laminated on the resin film constituting the base material layer 1 by melt extrusion or solution coating of the adhesive constituting the adhesive layer 2. After being laminated and dried by (liquid coating), the adhesive layer 2 is formed by baking at a temperature equal to or higher than the melting point of the adhesive. By performing baking, the adhesive strength between the metal layer 3 and the adhesive layer 2 is improved. Similarly, for a multilayer film in which the metal layer 3 and the adhesive layer 2 prepared in advance in the thermal laminating method are laminated, the adhesive constituting the adhesive layer 2 is melt-extruded or solution into the metal foil constituting the metal layer 3 in the same manner. After being laminated by coating and dried, it is formed by baking at a temperature equal to or higher than the melting point of the adhesive constituting the adhesive layer 2.

  Moreover, the formation of the laminated body A by the sand laminating method is performed by, for example, melting and extruding the adhesive constituting the adhesive layer 2 on the upper surface of the metal layer 3 and bonding the resin film constituting the base material layer 1 to the barrier layer. Can be performed. At this time, it is desirable that the resin film is bonded and temporarily bonded, and then heated again to perform the main bonding. In the sand lamination method, the adhesive layer 2 may be multilayered with different resin types. In this case, a multilayer film in which the base material layer 1 and the adhesive layer 2 are laminated is prepared in advance, the adhesive constituting the adhesive layer 2 is melt-extruded on the upper surface of the metal layer 3, and the multilayer resin film and the thermal lamination method are used. What is necessary is just to laminate. Thereby, the adhesive layer 2 which comprises a multilayer film, and the adhesive layer 2 laminated | stacked on the upper surface of the metal layer 3 adhere | attach, and the two-layer adhesive layer 2 is formed. When the adhesive layer 2 is multilayered with different resin types, a multilayer film in which the metal layer 3 and the adhesive layer 2 are laminated is prepared in advance, and the adhesive constituting the adhesive layer 2 is melted on the base material layer 1 It may be extruded and laminated with the adhesive layer 2 on the metal layer 3. Thereby, the adhesive layer 2 composed of two different adhesives is formed between the multilayer resin film and the base material layer 1.

  Next, a sealant layer 4 (a first sealant layer and a second sealant layer) is laminated on the metal layer 3 of the laminate A. For example, the sealant layer 4 is laminated on the metal layer 3 of the laminate A. For example, the first sealant layer and the second sealant layer are sequentially formed on the metal layer 3 of the laminate A by a gravure coating method, a roll coating method, or the like. It can carry out by the method of apply | coating by the method. Moreover, lamination | stacking of the sealant layer 4 to the metal layer 3 of the laminated body A can also be performed by the method of coextruding a 1st sealant layer and a 2nd sealant layer on the metal layer 3 of the laminated body A.

  As described above, a laminate composed of the base material layer 1 / adhesion layer 2 / metal layer 3 / sealant layer 4 (first sealant layer, second sealant layer) whose surface is subjected to chemical conversion treatment as necessary is formed. However, in order to strengthen the adhesiveness of the adhesive layer 2, it may be further subjected to a heat treatment such as hot roll contact, hot air, near or far infrared irradiation, dielectric heating, heat resistance heating and the like. Examples of such heat treatment conditions include 150 to 250 ° C. and 1 to 10 hours.

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

5. Characteristics and Applications of Battery Packaging Material The battery packaging material of the present invention has the specific sealant layer described above, so that the sealed space is formed from the outside in a state where the sealant layers are heat sealed to form a sealed space. However, if it is exposed to heating conditions in which the temperature is raised to a set temperature T ° C. determined between 140 ° C. and 160 ° C. at a rate of temperature increase of 3 ° C./min in a pressure atmosphere that is 1 atm higher, the packaging material is removed until T ° C. is reached. The packaging material can be opened within 30 minutes after reaching T ° C. without opening. More specifically, the battery packaging material of the present invention does not open the packaging material until the set temperature T ° C. defined between 140 to 160 ° C. is reached under the heating conditions shown below. It becomes possible to provide the property of opening within 30 minutes after reaching ° C.
<Heating conditions>
(1) A recess having a depth of 3 mm, a length of 35 and a width of 50 mm is formed at the center of the battery packaging material cut into a shape having a length of 80 mm and a width of 150 mm, and is formed into a shape having an edge around the recess. Two battery packaging materials molded into such a shape are prepared.
(2) The edge portions are overlapped so that the two sealant layers of the battery packaging material formed as described above face each other, and the edge portions are heat sealed (175 ° C., 3 seconds, surface pressure 1.4 MPa), A case having a sealed internal space (pressure 1 atm) is formed.
(3) Put the battery packaging material in the above-mentioned case into an oven that can be depressurized, set the pressure in the oven to 0 atm, 140 to 160 ° C. at a temperature increase rate of 3 ° C./min. The temperature is heated to a set temperature T ° C. determined between and after reaching the set temperature T ° C., the set temperature T ° C. is maintained.

  The battery packaging material of the present invention has the above-described opening characteristics, and is gently opened by micro-cleavage at the time of opening. Therefore, when the temperature is raised to the set temperature T ° C., the packaging material does not reach until T ° C. is reached. It is used as a battery packaging material that is set so that the packaging material is opened quickly after reaching T ° C. without opening. The set temperature T determined by the battery is set between 140 and 160 ° C., and the set temperature differs depending on the type of battery to be packaged, usage, safety standards, and the like. For example, some batteries have the set temperature T set to 140 ° C., while other batteries have the set temperature T set to 160 ° C. for safety standards. The battery packaging material of the present invention is provided as a packaging material having a sealing property and an unsealing property corresponding to the set temperature required by the battery to be applied. In addition, the time required for the battery to transition to the unsealed state after reaching T ° C. is determined within a range in which safety can be ensured, and varies depending on the type and use of the battery, the rate of temperature increase, etc. Is within 30 minutes, and the battery packaging material of the present invention can satisfy the time.

  Specifically, the battery packaging material of the present invention can be used for sealing and housing battery elements such as a positive electrode, a negative electrode, and an electrolyte, and is provided with a space for housing the battery element. . The space is formed by press-molding a laminated sheet cut into a short shape.

  More specifically, a battery element including at least a positive electrode, a negative electrode, and an electrolyte, with 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 protrude outward, A battery using a battery packaging material by covering the periphery of the battery element so that a flange portion (region where the sealant layers contact each other) can be formed, and heat-sealing and sealing the sealant layers of the flange portion. Is provided. In addition, when accommodating a battery element using the battery packaging material of the present invention, it is used so that the second sealant layer of the battery packaging material of the present invention is on the inner side (surface in contact with the battery element).

  The battery packaging material of the present invention may be used for either a primary battery or a secondary battery, but is preferably a secondary battery. The type of secondary battery to which the battery packaging material of the present invention is applied is not particularly limited. For example, a lithium ion battery, a lithium ion polymer battery, a lead battery, a nickel / hydrogen battery, a nickel / cadmium battery , Nickel / iron livestock batteries, nickel / zinc livestock batteries, silver oxide / zinc livestock batteries, metal-air batteries, polyvalent cation batteries, capacitors, capacitors and the like. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable applications for the battery packaging material of the present invention.

B. Method for Screening Resin Component Used in Sealant Layer The present invention further provides a method for screening (selecting) a resin component used in a sealant layer formed on a battery packaging material having the above-described sealing and unsealing properties. I will provide a.

Specifically, the screening method is a method of screening a resin component used in a sealant layer formed on a battery packaging material,
When the battery packaging material is heated to a set temperature T ° C. determined between 140 ° C. and 160 ° C., the packaging material is not opened until the temperature reaches T ° C. After the temperature reaches T ° C., the packaging material is quickly opened. Used for batteries set to open,
The battery packaging material comprises a laminate having a base layer, an adhesive layer, a metal layer, and a sealant layer in this order, and the sealant layer includes a first sealant layer located on the metal layer side, and the first sealant layer. Having a second sealant layer laminated on the sealant layer and located in the innermost layer,
At least acid-modified polyolefin is selected as the resin component forming the first sealant layer, at least polyolefin is selected as the resin component forming the second sealant layer, and the first sealant layer and the second sealant layer are represented by the following formula ( 1) and (2)
−10 ≦ T ₁ −T ≦ −5 (1)
−5 ≦ T ₂ −T ≦ 5 (2)
T ₁ : Melting point (° C.) of the first sealant layer
T ₂ : Melting point (° C.) of the second sealant layer
The resin component forming the first sealant layer and the second sealant layer is selected so as to satisfy the above.

  The meaning of each term in the screening method is as described in the column “A. Battery packaging material”.

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

Example 1-12 and Comparative Example 1-12
[Manufacture of battery packaging materials]
A metal layer made of aluminum foil (thickness 40 μm) subjected to chemical conversion treatment on both surfaces of the base material layer 1 made of a biaxially stretched nylon film (thickness 25 μm) coated with a slip material on one side. 3 was laminated by a dry lamination method. Specifically, a two-component urethane adhesive (a polyol compound and an aromatic isocyanate compound) was applied to one surface of an aluminum foil to form an adhesive layer 2 (thickness 4 μm) on the metal layer 3. Next, after bonding the adhesive layer 2 and the base material layer 1 on the metal layer 3 under pressure and heating, an aging treatment is carried out at 40 ° C. for 24 hours, whereby base material layer 1 / adhesive layer 2 / metal layer 3 A laminate was prepared. In addition, the chemical conversion treatment of the aluminum foil used as the metal layer 3 is performed by rolling a treatment liquid composed of a phenol resin, a chromium fluoride compound, and phosphoric acid so that the coating amount of chromium is 10 mg / m ² (dry weight). The coating was applied to both surfaces of the aluminum foil and baked for 20 seconds under the condition that the film temperature was 180 ° C. or higher.

  Next, the first sealant layer (on the metal layer 3) is coextruded in a molten state with the resin component forming the first sealant layer and the resin component forming the second sealant layer on the metal layer 3 side of the laminate. A thickness of 25 μm) and a second sealant layer (thickness of 25 μm) were laminated. In addition, about the resin component which forms a 1st sealant layer and a 2nd sealant layer, it is as showing to Tables 2-4. Moreover, about melting | fusing point of each sealant layer, it is the value measured by DSC method. Thus, a battery packaging material comprising a laminate in which the base material layer 1 / adhesive layer 2 / metal layer 3 / first sealant layer / second sealant layer was laminated in order was obtained.

[Evaluation of sealing and unsealing properties of battery packaging materials]
After each battery packaging material is cut to 80 mm × 150 mm, a 35 mm × 50 mm diameter mold (female mold) and a corresponding mold (male mold) with a 0.4 MPa pressure of 3.0 mm Cold forming to a depth, a recess was formed at the center. Regarding the battery packaging material after cold forming, it was visually observed whether or not pinholes were generated on the surface of the base material layer 1, and no pinholes were observed in any of the battery packaging materials. It was. Also, the two battery packaging materials after molding are stacked so that the sealant layers face each other, and the edge where the sealant layers overlap is heat sealed (175 ° C., 3 seconds, surface pressure 1.4 MPa). A case with a sealed internal space (pressure 1 atm) was formed. The battery packaging material thus made into a case is put in an oven that can be depressurized, and the pressure in the oven is set to 0 atm, and the temperature is raised to a set temperature T ° C. at a rate of 3 ° C./min. Then, T ° C was maintained for 30 minutes, and the state of the battery packaging material was visually confirmed at the time immediately before reaching T ° C and 30 minutes after reaching T ° C. In this performance evaluation, the set temperature was set to three types of 140, 150, and 160 ° C.

  Based on the results observed in the test, the sealing and unsealing properties of each battery packaging material were evaluated according to the following criteria.

The obtained results are shown in Tables 2-4. From this result, in the battery packaging material including the first sealant layer containing the acid-modified polyolefin and the second sealant layer containing the polyolefin, the difference between the melting point T ₁ of the first sealant layer and the set temperature T (T ₁ −T) Is −10 ° C. or more and −5 ° C. or less and the difference (T ₂ −T) between the melting point T ₂ of the second sealant layer and the set temperature T satisfies −5 ° C. or more and + 5 ° C. or less. Until the temperature reaches T ° C., at least a part of the sealant layer 4 is peeled off from the interface of the metal layer 3, but the sealant layer 4 becomes a bag shape and maintains the sealed state inside, and 30 minutes after reaching the set temperature T ° C. Later, a minute tear such as a pinhole occurred in the sealant layer 4 at the part peeled off from the metal layer 3, and it was possible to guide the opening in a gentle state. In contrast, the difference between the melting point T ₁ of the first sealant layer and the set temperature T (T ₁ −T) and the difference between the melting point T ₂ of the second sealant layer and the set temperature T (T ₂ −T) If either of the above conditions is not satisfied, an opening state is reached before reaching the set temperature T ° C, and cohesive failure or breakage of the sealant layer occurs in the heat seal portion, or the set temperature T ° C Even after 30 minutes, the unsealed state could not be obtained.

Example 13
A battery packaging material was produced in the same manner as in Example 1-12, except for the following points.
A random copolymer of propylene-ethylene modified with maleic acid (MFR: 7, melting point 140 ° C.) was used as the resin for forming the first sealant layer.
A random copolymer of propylene-ethylene (MFR: 7, melting point: 147 ° C.) was used as a resin for forming the second sealant layer, and 0.025% by mass of erucic acid amide was added as a slip agent.
-The thickness of the 1st sealant layer shall be 15 micrometers, and the thickness of the 2nd sealant layer shall be 15 micrometers.

Example 14
A battery packaging material was produced in the same manner as in Example 13 except that the thickness of the first sealant layer was 20 μm.

Example 15
A battery packaging material was produced in the same manner as in Example 13, except that the amount of erucic acid amide was 0.12% by mass.

Example 16
A battery packaging material was produced in the same manner as in Example 14 except that the amount of erucic acid amide was 0.12% by mass.

Example 17
A battery packaging material was produced in the same manner as in Example 13 except that 0.12% by mass of erucamide was added to the first sealant layer.

Example 18
A battery packaging material was produced in the same manner as in Example 14 except that 0.12% by mass of erucic acid amide was added to the first sealant layer.

[Evaluation of insulation against cracks]
After cutting the battery packaging material obtained in Examples 13 to 18 into a sheet piece of 150 mm (MD direction) × 80 mm (TD direction, lateral direction), a molding die (female mold) having a diameter of 35 mm × 50 mm and With a molding die (male type) corresponding to this, cold molding was performed at a depth of 3.0 mm at 0.4 MPa, and a concave portion was formed in the center portion of the sheet piece. Next, these sheet pieces are folded in two in the MD direction (longitudinal direction) so that the second sealant layer is inside, and the end portion is cut so that the length in the MD direction after bending becomes 6.3 mm. The packaging material was molded. A dummy cell (PP block of 3.0 mm × 49 mm × 29 mm) with an electrode tab with a tab seal material attached is installed in the recess of the molded packaging material, and fixed so that the tab seal material portion of the dummy cell comes to the sealing portion of the packaging material. . Next, heat sealing was performed under the conditions of an 80 mm side, a width of 5 mm, 170 ° C., 2.0 MPa, and 5 seconds so that the metal terminal extended outside from one side where the packaging material opened. Subsequently, one side of the 6.3 mm side was heat-sealed under the conditions of 5 mm width, 170 ° C., 0.5 MPa, and 3 seconds to produce a pouch-type exterior body having an opening on one side. This was dried in a dry room for 12 hours. Next, the electrolytic solution was put into the dried outer package, and the opening was hermetically sealed with a width of 3 mm. This was held at 60 ° C. for 5 hours, then cooled, and the other side of the remaining 6.3 mm was sealed under the conditions of a width of 3 mm, a surface pressure of 1.0 MPa, a seal temperature of 170 ° C., and a seal time of 3.0 seconds. This final seal part is bent at 90 ° C in the direction of the molded convex part and then returned, and then an insulation evaluation test against cracks is performed using an impulse application method (made by Nippon Technate Co., Ltd., lithium ion battery insulation tester). did. First, 20 samples were prepared, and an impulse voltage of an applied voltage of 100 V was applied between the negative electrode terminal of each lithium ion battery and the aluminum foil, and the voltage drop after 99 msec was determined to be within 20 V. . The percentage of acceptance (%) is shown in Table 5.

  From the results shown in Table 5, it was revealed that the insulation against cracks of the battery packaging material can be improved by blending erucamide as a slip agent in the second sealant layer. In particular, in Examples 15 to 18 in which the slip agent amount of the first sealant layer or the second sealant layer was 0.012% by mass, it was revealed that the insulation against cracks was very high.

[Formability evaluation]
The battery packaging materials obtained in Examples 13 to 18 were cut into 90 mm (MD direction) × 150 mm (TD direction, lateral direction) sheet pieces, and then a molding die (female mold) with a diameter of 35 mm × 50 mm. And a molding die (male) corresponding thereto, from the second sealant layer side, it was cold-molded to an arbitrary depth at 0.9 MPa, and a concave portion was formed at the center. Next, it was visually observed whether or not a pinhole was generated on the surface of the portion where the concave portion of the second sealant layer was formed. The number of samples was 20, and those in which no pinholes were generated were accepted. Similarly, the depth of the recess was increased by 0.5 mm, and the presence or absence of pinholes was confirmed for 20 samples. Table 6 shows the depth (mm) of the recesses determined to be able to suppress the occurrence of pinholes in the second sealant layer for the battery packaging materials obtained in Examples 13-18. The depth of the recess was calculated as follows. For example, when the depth of the recess is formed to be 5.0 mm, no pinhole is generated in all 20 samples, and when the depth of the recess is 5.5 mm, no pinhole is generated. In the case of N pieces, the depth (mm) of the concave portion determined to be able to suppress the occurrence of pinholes was calculated by the following formula.
Depth of recess determined to suppress generation of pinholes (mm) = 5.0 (mm) + 0.5 (mm) x (N / 20)

  From the results shown in Table 6, in Examples 15 to 18 in which the second sealant layer contains a large amount of slip agent, the recesses can be formed more deeply than in Examples 13 to 14 with less slip material, and the moldability is improved. It became clear that it was expensive. In particular, in Examples 15 to 18 in which the slip agent amount of the first sealant layer or the second sealant layer is 0.12% by mass, the generation of pinholes is suppressed even when the depth of the recess exceeds 7.00 mm. It was revealed that the moldability was very high.

DESCRIPTION OF SYMBOLS 1 Base material layer 2 Adhesive layer 3 Metal layer 4 Sealant layer 4a 1st sealant layer 4b 2nd sealant layer 10 Fine cleavage

Claims (8)

When the temperature is raised to a set temperature T ° C determined between 140 ° C and 160 ° C, the packaging material is not opened until the temperature reaches T ° C. After reaching T ° C, the packaging material is opened quickly. A battery packaging material used for a battery,
It consists of a laminate having at least a base material layer, an adhesive layer, a metal layer, and a sealant layer in this order,
The sealant layer is located on the metal layer side, a first sealant layer comprising an acid-modified polyolefin, located in the innermost layer is laminated to the first sealant layer consists of two layers of a second sealant layer comprising a polyolefin ,
The first sealant layer and the second sealant layer are represented by the following formulas (1) and (2):
−10 ≦ T ₁ −T ≦ −5 (1)
−5 ≦ T ₂ −T ≦ 5 (2)
T ₁ : Melting point (° C.) of the first sealant layer
T ₂ : Melting point (° C.) of the second sealant layer
Is satisfied ,
In a state where the battery is exposed to a high temperature up to T ° C., the first sealant layer changes to a molten state, and at least a part of the sealant layer peels from the interface between the metal layer and the sealant layer, The second sealant layer functions to maintain a hermetic state while being swollen by an internal pressure, and after reaching T ° C., the sealant layer is finely cleaved and gently releases the gas inside the battery , Battery packaging material.   The battery packaging material according to claim 1, wherein the acidic polyolefin contained in the first sealant layer contains at least propylene as a constituent monomer.   The battery packaging material according to claim 1 or 2, wherein the polyolefin contained in the second sealant layer contains at least propylene as a constituent monomer.   The battery packaging material according to claim 1, wherein the first sealant layer has a thickness of 5 to 40 μm, and the second sealant layer has a thickness of 5 to 40 μm.   The battery packaging material according to any one of claims 1 to 4, wherein the metal layer is an aluminum foil.   The battery packaging material according to claim 1, wherein at least one of the first sealant layer and the second sealant layer contains a slip agent.   The battery by which the battery element provided with the positive electrode, the negative electrode, and the electrolyte is accommodated in the packaging material for batteries in any one of Claims 1-6. A method for screening a resin component used in a sealant layer formed on a battery packaging material,
When the battery packaging material is heated to a set temperature T ° C. determined between 140 ° C. and 160 ° C., the packaging material is not opened until the temperature reaches T ° C. After the temperature reaches T ° C., the packaging material is quickly opened. Used for batteries set to open,
The battery packaging material comprises a laminate having a base layer, an adhesive layer, a metal layer, and a sealant layer in this order, and the sealant layer includes a first sealant layer located on the metal layer side, and the first sealant layer. laminated on the sealant layer made of two layers which have a second sealant layer positioned as the innermost layer,
In the battery packaging material, when the battery is exposed to a high temperature up to T ° C., the first sealant layer changes to a molten state, and at least the sealant layer from the interface between the metal layer and the sealant layer. The second sealant layer functions to maintain a sealed state while being swollen by internal pressure, and the sealant layer is finely cleaved after reaching T ° C. and gently releases the gas inside the battery. Is what
At least acid-modified polyolefin is selected as the resin component forming the first sealant layer, at least polyolefin is selected as the resin component forming the second sealant layer, and the first sealant layer and the second sealant layer are represented by the following formula ( 1) and (2)
−10 ≦ T ₁ −T ≦ −5 (1)
−5 ≦ T ₂ −T ≦ 5 (2)
T ₁ : Melting point (° C.) of the first sealant layer
T ₂ : Melting point (° C.) of the second sealant layer
The screening method is characterized in that the resin component forming the first sealant layer and the second sealant layer is selected so as to satisfy the above.