Battery packaging laminate

Abstract

To provide a battery packaging laminate which has excellent cold formability and puncture resistance, and carbon neutrality, and also uses biomass-derived raw materials.SOLUTION: A laminate in which at least a substrate layer 1, an adhesive layer, a metal foil layer, and a sealant layer are sequentially laminated in this order is a battery packaging laminate. The substrate layer 1 is a biaxial oriented film satisfying the following conditions (a), (b), and (c): (a) thickness is 8-30 μm; (b) a biomass-derived carbon content measured by a radioactive carbon (C14) measurement is 1-30% with respect to the total carbon in the substrate layer 1; (c) puncture resistance measured by JIS Z 1707 method is 0.7 N / μm or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a laminated film that is suitably used as an exterior material for a lithium ion battery. [Background technology]

[0002] In recent years, lithium batteries have been used in a wide variety of applications, including as small, high-capacity power sources for personal computers, portable terminal devices (e.g., mobile phones and PDAs), video cameras, electric vehicles, energy storage batteries, robots, and satellites. Lithium batteries are typically housed in cylindrical or rectangular metal cans, or in pouches made of multilayer film consisting of an outermost layer, aluminum, and a sealant layer. Among these, pouch-shaped exteriors made of multilayer film have become increasingly popular in recent years due to their flexibility in shape, compact size, and heat dissipation performance against battery heat generation.

[0003] The properties required for battery packaging materials include cold formability, hermetic sealing, puncture resistance, and pinhole resistance. Conventionally, the above-mentioned battery packaging materials have been made by laminating polyamide film / polyester film, as in Patent Document 1, for example, but these films have traditionally been made from petroleum-derived raw materials.

[0004] Meanwhile, in recent years, in order to build a recycling-oriented society, the use of biomass as an alternative to fossil fuels has been attracting attention in the materials field. Biomass is an organic compound formed by photosynthesis from carbon dioxide and water, and by using it, it can be converted back into carbon dioxide and water, making it a so-called carbon-neutral raw material (the amount of carbon dioxide emitted and absorbed in the environment is the same, so the increase in carbon dioxide, a greenhouse gas, can be suppressed). The practical application of biomass plastics made from these biomass raw materials is rapidly progressing, and a biaxially oriented polyamide film made from biomass-derived raw materials has also been proposed (Patent Document 2). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 9-115428 [Patent Document 2] International Publication No. 2020 / 170714 Summary of the Invention [Problem to be solved by the invention]

[0006] An object of the present invention is to provide a laminate for packaging batteries that has excellent cold formability and puncture resistance, and is carbon-neutral and uses raw materials derived from biomass. [Means for solving the problem]

[0007] The present invention comprises the following components. [1] A laminate comprising at least a base layer 1, an adhesive layer, a metal foil layer, and a sealant layer laminated in this order, wherein the base layer 1 is a biaxially oriented polyamide film satisfying the following (a) to (c), the sealant layer is an unstretched polyolefin film, the unstretched polyolefin film being an unstretched polyolefin film containing 70 to 95 mass% of a polypropylene-based resin and 5 to 30 mass% of a linear low-density polyethylene-based resin at least part of which is derived from biomass, the sealant layer having a configuration comprising a seal layer, a core layer, and a laminate layer in this order, and wherein the polypropylene-based resin composition constituting the seal layer and the core layer Direct The difference in the content of linear low-density polyethylene is 1 to 28 mass %, and the polypropylene resin composition constituting the core layer and the laminate layer Direct A laminate for packaging batteries, wherein the difference in the content of linear low-density polyethylene is 1 to 28 mass %. (a) Thickness: 8 to 30 μm (b) The content of carbon derived from biomass as determined by radiocarbon (C14) measurement is 1 to 30% of the total carbon in the substrate layer 1. (c) Puncture strength measured according to JIS Z 1707 method is 0.7 N / μm or more [2] The laminate for battery packaging according to [1], wherein the base layer 1 is a biaxially stretched polyamide film consisting of a single layer formed from a resin composition containing polyamide 6 and polyamide at least part of whose raw materials are derived from biomass. [3] The laminate for battery packaging according to [1], wherein the base layer 1 is a biaxially stretched polyamide film consisting of at least two layers: a layer (layer A) formed from a resin composition containing polyamide 6 and a polyamide at least part of which is derived from biomass, and a layer (layer B) formed from a resin composition containing polyamide 6 and not containing a polyamide at least part of which is derived from biomass. [4] The laminate for battery packaging according to [2] or [3], wherein the polyamide at least a part of which is derived from biomass is at least one polyamide selected from the group consisting of polyamide 11, polyamide 410, polyamide 610, and polyamide 1010. [5] The laminate for battery packaging according to any one of [1] to [4], wherein the content of biomass-derived carbon in the sealant layer as determined by radiocarbon (C14) measurement is 3 to 30% of the total carbon in the sealant layer. [6] The laminate for battery packaging according to any one of [1] to [5], wherein a base material layer 2 having a thickness of 10 to 30 μm is further laminated on the surface of the base material layer 1 opposite to the metal foil layer. [7] The laminate for battery packaging according to [6], wherein the base material layer 2 is a biaxially oriented polyester film. [Effects of the Invention]

[0008] According to the present invention, a biaxially oriented polyamide film in which a polyamide resin polymerized from specific biomass-derived raw materials is blended with polyamide 6 is used as a base layer, and by laminating it with a sealant film in which polyethylene made from biomass-derived raw materials is blended with polypropylene, a laminated film for battery packaging that is excellent in cold formability and puncture resistance and is also carbon-neutral can be obtained. DETAILED DESCRIPTION OF THE INVENTION

[0009] [Base material layer 1] The base layer 1 of the present invention is a biaxially oriented polyamide film. The biaxially oriented polyamide film contains, as polyamide resins, 70 to 99% by mass of polyamide 6 and 1 to 30% by mass of polyamide at least partially derived from biomass. By containing 70% or more by mass of polyamide 6, the biaxially oriented polyamide film made of polyamide 6 can obtain the excellent mechanical strength, such as impact strength, and gas barrier properties against oxygen and the like, inherent to the biaxially oriented polyamide film. In addition, by containing 1 to 30% by mass of polyamide at least partially derived from biomass, not only is it less affected by fluctuations in terrestrial carbon dioxide levels, but it also has improved puncture resistance.

[0010] In one preferred embodiment, the substrate layer 1 is a biaxially stretched polyamide film consisting of a single layer formed from a resin composition containing polyamide 6 and polyamide at least part of which is derived from biomass.

[0011] In another preferred embodiment, the base layer 1 is a biaxially stretched polyamide film consisting of at least two layers: a layer (A layer) formed from a resin composition containing polyamide 6 and a polyamide at least partly derived from biomass, and a layer (B layer) formed from a resin composition containing polyamide 6 and not containing a polyamide at least partly derived from biomass. Specific configurations include a two-layer structure of A layer / B layer and a three-layer structure of B layer / A layer / B layer.

[0012] <Polyamide 6> The polyamide 6 used in the present invention is usually produced by ring-opening polymerization of ε-caprolactam. The polyamide 6 obtained by ring-opening polymerization is usually subjected to removal of lactam monomer with hot water, followed by drying and melt-extrusion in an extruder.

[0013] The relative viscosity of polyamide 6 is preferably 1.8 to 4.5, and more preferably 2.6 to 3.2. If the relative viscosity is less than 1.8, the impact strength of the film will be insufficient. If it is more than 4.5, the load on the extruder will increase, making it difficult to obtain an unstretched film before stretching.

[0014] As polyamide 6, in addition to polyamide 6 polymerized from commonly used fossil fuel-derived monomers, polyamide 6 chemically recycled from waste polyamide 6 products such as waste plastic products, waste tire rubber, fibers, fishing nets, etc. As a method for obtaining chemically recycled polyamide 6 from waste polyamide 6 products, for example, a method can be used in which used polyamide products are collected, depolymerized to obtain ε-caprolactam, which is then purified and then polymerized into polyamide 6.

[0015] In addition, it is possible to use mechanically recycled polyamide 6, which is waste material generated during the polyamide film manufacturing process. Mechanically recycled polyamide 6 is a raw material that is made by recovering waste material generated during the manufacturing of biaxially oriented polyamide film, such as non-standard, unshippable film and offcuts (edge ​​trim), and pelletizing it through melt extrusion or compression molding.

[0016] <Polyamide made at least partly from biomass-derived raw materials> Examples of polyamides used in the present invention, at least a part of which is derived from biomass, include polyamide 11, polyamide 410, polyamide 610, and polyamide 1010.

[0017] Polyamide 11 is a polyamide resin having a structure in which monomers having 11 carbon atoms are bonded via amide bonds. Polyamide 11 is usually obtained using aminoundecanoic acid or undecane lactam as a monomer. In particular, aminoundecanoic acid is a monomer obtained from castor oil, and is therefore desirable from the viewpoint of carbon neutrality.

[0018] Polyamide 410 is a polyamide resin having a structure in which a monomer having four carbon atoms is copolymerized with a diamine having ten carbon atoms. Polyamide 410 is usually made from sebacic acid and tetramethylenediamine. From an environmental perspective, sebacic acid made from castor oil, a vegetable oil, is preferred. The sebacic acid used here is preferably obtained from castor oil from the standpoint of environmental protection (particularly from the standpoint of carbon neutrality).

[0019] Polyamide 610 is a polyamide resin with a structure formed by polymerizing a diamine with six carbon atoms and a dicarboxylic acid with ten carbon atoms. Hexamethylenediamine and sebacic acid are usually used. Of these, sebacic acid is a monomer obtained from castor oil, making it desirable from the perspective of carbon neutrality.

[0020] Polyamide 1010 is a polyamide resin having a structure in which a diamine having 10 carbon atoms and a dicarboxylic acid having 10 carbon atoms are polymerized. Typically, 1,10-decanediamine (decamethylenediamine) and sebacic acid are used in polyamide 1010. Decamethylenediamine and sebacic acid are monomers obtained from castor oil, and are therefore desirable from the perspective of carbon neutrality.

[0021] The lower limit of the content of the polyamide at least partly derived from biomass in the base layer of the present invention is not particularly limited, but is preferably 1% by mass, more preferably 3% by mass or more. The upper limit of the content is 30% by mass, more preferably 20% by mass. If the content of the polyamide at least partly derived from biomass exceeds 30% by mass, the molten film may become unstable when cast, making it difficult to obtain a homogeneous unstretched film.

[0022] <Subsidiary materials, additives> The biaxially oriented polyamide film of the substrate layer may contain various additives such as other thermoplastic resins, lubricants, heat stabilizers, antioxidants, antistatic agents, anti-fogging agents, ultraviolet absorbers, dyes, pigments, etc., as needed.

[0023] <Other thermoplastic resins> The biaxially oriented polyamide film of the base layer may contain a thermoplastic resin in addition to the polyamide 6 and a polyamide resin at least partially derived from biomass, as long as the objectives of the present invention are not impaired. Examples include polyamide-based resins such as polyamide 12 resin, polyamide 66 resin, polyamide 6·12 copolymer resin, polyamide 6·66 copolymer resin, and polyamide MXD6 resin. If necessary, thermoplastic resins other than polyamide-based resins, such as polyester-based polymers such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene-2,6-naphthalate, and polyolefin-based polymers such as polyethylene and polypropylene, may also be contained. It is preferable that the raw materials for these thermoplastic resins are derived from biomass, as this does not affect the increase or decrease in terrestrial carbon dioxide and therefore reduces the environmental burden.

[0024] <Lubricant> The biaxially stretched polyamide film of the base layer can contain fine particles as a lubricant to improve the slipperiness and make it easier to handle. The fine particles can be appropriately selected from inorganic fine particles such as silica, kaolin, and zeolite, and polymeric organic fine particles such as acrylic and polystyrene-based fine particles. From the viewpoints of transparency and slipperiness, it is preferable to use silica fine particles. The average particle diameter of the fine particles is preferably 0.5 to 5.0 μm, more preferably 1.0 to 3.0 μm. If the average particle diameter is less than 0.5 μm, a large amount is required to achieve good slipperiness. On the other hand, if the average particle diameter exceeds 5.0 μm, the surface roughness of the film tends to be too great, resulting in a poor appearance.

[0025] When the silica fine particles are used, the pore volume of the silica is preferably in the range of 0.5 to 2.0 ml / g, more preferably 0.8 to 1.6 ml / g. If the pore volume is less than 0.5 ml / g, voids are likely to occur, resulting in poor film transparency, while if the pore volume exceeds 2.0 ml / g, the fine particles tend to be less likely to form protrusions on the surface.

[0026] The biaxially stretched polyamide film of the base layer may contain a fatty acid amide and / or a fatty acid bisamide to improve slipperiness. Examples of fatty acid amides and / or fatty acid bisamides include erucic acid amide, stearic acid amide, ethylene bisstearic acid amide, ethylene bisbehenic acid amide, and ethylene bisoleic acid amide. The content of the fatty acid amide and / or fatty acid bisamide is preferably 0.01 to 0.40% by mass, and more preferably 0.05 to 0.30% by mass. If the content of the fatty acid amide and / or fatty acid bisamide is less than the above range, slipperiness tends to deteriorate. On the other hand, if the content exceeds the above range, wettability tends to deteriorate.

[0027] When the base layer 1 is composed of at least two layers, Layer A and Layer B, the fine particles and fatty acid amide and / or fatty acid bisamide are preferably contained only in Layer B. By reducing the amount of these added to Layer A, it is expected that a film with excellent transparency and slipperiness can be obtained.

[0028] <Antioxidants> The biaxially oriented polyamide film of the substrate layer may contain an antioxidant. Phenol-based antioxidants are preferred. The phenol-based antioxidant is preferably a fully hindered phenolic compound or a partially hindered phenolic compound. Examples of the phenol-based antioxidant include tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, and 3,9-bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane. The inclusion of a phenol-based antioxidant improves the film-forming operability of the biaxially oriented polyamide film. In particular, when recycled films are used as raw materials, the resin is prone to thermal degradation, which can lead to operational problems in film production and increased production costs. In contrast, the inclusion of an antioxidant suppresses thermal degradation of the resin and improves operational efficiency.

[0029] It is preferable that the base layer 1 does not contain a polyamide elastomer or a polyolefin elastomer. By not containing soft resins such as polyamide elastomers or polyolefin elastomers or substances that generate a large amount of voids, friction pinhole resistance is improved.

[0030] [Biaxially oriented polyamide film] The thickness of the base material layer is not particularly limited, but when used as a packaging material, it is usually 100 μm or less, and a thickness of 5 to 50 μm is generally used, and a thickness of 8 to 30 μm is particularly used.

[0031] The biaxially stretched polyamide film of the base layer preferably has a heat shrinkage rate of 0.6 to 3.0% in both the MD and TD directions at 160°C for 10 minutes, more preferably 0.6 to 2.5%. If the heat shrinkage rate exceeds 3.0%, curling or shrinkage may occur when heat is applied in subsequent processes such as lamination or printing. Furthermore, the lamination strength with the sealant film may be weakened. Although it is possible to reduce the heat shrinkage rate to less than 0.6%, this may result in mechanical embrittlement. Furthermore, this is not preferred because it reduces productivity.

[0032] The impact strength of the biaxially stretched polyamide film is preferably 0.7 J / 15 μm or more, and more preferably 0.9 J / 15 μm or more.

[0033] The puncture strength of the biaxially oriented polyamide film is preferably 0.7 N / μm or more, and more preferably 0.9 N / μm or more.

[0034] The haze value of biaxially oriented polyamide film is preferably 10% or less, more preferably 7% or less, and even more preferably 5% or less. A low haze value means good transparency and gloss, so when used in packaging bags, beautiful printing is possible and commercial value is increased. Since the addition of fine particles to improve the film's slipperiness increases the haze value, if the film has two or more layers, adding fine particles only to the surface layer will reduce the haze value.

[0035] The dynamic friction coefficient of the biaxially stretched polyamide film is preferably 1.0 or less, more preferably 0.7 or less, and even more preferably 0.5 or less. A small dynamic friction coefficient of the film improves the slipperiness and makes the film easier to handle. If the dynamic friction coefficient of the film is too small, it becomes too slippery and difficult to handle, so the dynamic friction coefficient of the biaxially stretched polyamide film of the present invention is preferably 0.15 or more.

[0036] The biaxially oriented polyamide film preferably contains 1 to 30 mol% of biomass-derived carbon (also known as biomass content) based on radiocarbon (C14) measurement according to ASTM D6866-16 Method B, relative to the total carbon in the polyamide film. Atmospheric carbon dioxide contains a certain proportion of C14 (105.5 pMC), and it is known that the C14 content in plants that grow by absorbing atmospheric carbon dioxide, such as corn, is also approximately 105.5 pMC. It is also known that fossil fuels contain very little C14. Therefore, the proportion of biomass-derived carbon can be calculated by measuring the proportion of C14 in the total carbon atoms in the film.

[0037] [Method for producing biaxially oriented polyamide film] The biaxially stretched polyamide film of the substrate layer can be produced by a known production method, and a typical production example will be described below.

[0038] First, the raw resin is melt-extruded using an extruder, extruded through a T-die into a film, and cast onto a cooling roll to cool, yielding an unstretched film. The resin melting temperature is preferably 220 to 350°C. If the temperature is lower than this, unmelted material may be generated, resulting in defects and other poor appearance. If the temperature is higher than this, deterioration of the resin may be observed, resulting in a decrease in molecular weight and a deterioration in appearance. The die temperature is preferably 250 to 350°C.

[0039] When producing a biaxially stretched polyamide film in which at least two layers, Layer A and Layer B, are laminated, a coextrusion method using a feed block, a multi-manifold, or the like can be used to obtain an unstretched film in which Layer A and Layer B are laminated. When laminating by coextrusion, it is desirable that the polyamide resin compositions used for Layer A and Layer B have a small difference in melt viscosity between Layer A and Layer B.

[0040] The cooling roll temperature is preferably −30 to 80° C., more preferably 0 to 50° C. To obtain an unstretched film by casting the film-like molten material extruded from the T-die onto a rotating cooling drum and cooling it, for example, a method using an air knife or an electrostatic adhesion method in which a static charge is applied can be preferably used. The latter is particularly preferred.

[0041] It is also preferable to cool the surface of the cast unstretched film opposite the cooling roll. For example, it is preferable to use a method in which a cooling liquid in a tank is brought into contact with the surface of the unstretched film opposite the cooling roll, a method in which a vaporizing liquid is applied with a spray nozzle, or a method in which a high-velocity fluid is sprayed onto the surface to cool the film. The unstretched film thus obtained is stretched biaxially to obtain the biaxially stretched polyamide film of the present invention.

[0042] The stretching method may be either a simultaneous biaxial stretching method or a sequential biaxial stretching method. In either case, multi-stage stretching such as one-stage stretching or two-stage stretching can be used as the MD stretching method. As will be described later, multi-stage MD stretching such as two-stage stretching is preferred over single-stage stretching in terms of physical properties and uniformity of physical properties in the MD and TD directions (isotropy). Roll stretching is preferred for MD stretching in the sequential biaxial stretching method.

[0043] The lower limit of the MD stretching temperature is preferably 50°C, more preferably 55°C, and even more preferably 60°C. If the temperature is less than 50°C, the resin does not soften and stretching may become difficult. The upper limit of the MD stretching temperature is preferably 120°C, more preferably 115°C, and even more preferably 110°C. If the temperature exceeds 120°C, the resin may become too soft and stable stretching may not be possible.

[0044] The lower limit of the stretching ratio in the MD direction (when stretching is performed in multiple stages, the total stretching ratio obtained by multiplying each stretching ratio) is preferably 2.2 times, more preferably 2.5 times, and even more preferably 2.8 times. If it is less than 2.2 times, the thickness accuracy in the MD direction will decrease, and the crystallinity will become too low, which may result in a decrease in impact strength. The upper limit of the stretching ratio in the MD direction is preferably 5.0 times, more preferably 4.5 times, and most preferably 4.0 times. If it exceeds 5.0 times, subsequent stretching may become difficult.

[0045] When stretching in the MD direction is performed in multiple stages, the above-mentioned stretching is possible in each stretching, but the stretching ratios must be adjusted so that the product of all MD stretching ratios is 5.0 or less. For example, in the case of two-stage stretching, the first stage stretching is preferably 1.5 to 2.1 times, and the second stage stretching is preferably 1.5 to 1.8 times.

[0046] The film stretched in the MD direction is stretched in the TD direction using a tenter, heat-set, and then relaxed (also called a relaxation treatment). The lower limit of the TD stretching temperature is preferably 50°C, more preferably 55°C, and even more preferably 60°C. If the temperature is lower than 50°C, the resin does not soften, and stretching may become difficult. The upper limit of the TD stretching temperature is preferably 190°C, more preferably 185°C, and even more preferably 180°C. If the temperature exceeds 190°C, crystallization may occur, making stretching difficult.

[0047] The lower limit of the stretching ratio in the TD direction (when stretching is performed in multiple stages, the total stretching ratio obtained by multiplying each stretching ratio) is preferably 2.8, more preferably 3.2, even more preferably 3.5, and particularly preferably 3.8. If it is less than 2.8, the thickness accuracy in the TD direction will decrease, and the crystallinity will become too low, which may result in a decrease in impact strength. The upper limit of the stretching ratio in the TD direction is preferably 5.5, more preferably 5.0, even more preferably 4.7, particularly preferably 4.5, and most preferably 4.3. If it exceeds 5.5, productivity may decrease significantly.

[0048] The lower limit of the heat setting temperature is preferably 210°C, more preferably 212°C. If the heat setting temperature is too low, the heat shrinkage rate becomes too large, which tends to deteriorate the appearance after lamination and reduce the laminate strength. The upper limit of the heat setting temperature is preferably 220°C, more preferably 218°C. If the heat setting temperature is too high, the impact strength tends to decrease.

[0049] The heat setting time is preferably 0.5 to 20 seconds, and more preferably 1 to 15 seconds. The heat setting time can be adjusted appropriately by balancing the heat setting temperature and the air speed in the heat setting zone. If the heat setting conditions are too weak, crystallization and orientation relaxation will be insufficient, resulting in the above problems. If the heat setting conditions are too strong, the film toughness will decrease.

[0050] Relaxation treatment after heat setting is effective in controlling the heat shrinkage rate. The temperature for relaxation treatment can be selected within the range from the heat setting temperature to the glass transition temperature (Tg) of the resin, but a heat setting temperature of -10°C to Tg + 10°C is preferred. If the relaxation temperature is too high, the shrinkage rate will be too fast, which can cause distortion, and is therefore undesirable. Conversely, if the relaxation temperature is too low, relaxation treatment will not occur and the film will simply become loose, which will not reduce the heat shrinkage rate and will result in poor dimensional stability.

[0051] The lower limit of the relaxation rate in the relaxation treatment is preferably 0.5%, more preferably 1%. If it is less than 0.5%, the heat shrinkage rate may not be reduced sufficiently. The upper limit of the relaxation rate is preferably 20%, more preferably 15%, and even more preferably 10%. If it exceeds 20%, sagging may occur in the tenter, making production difficult.

[0052] Furthermore, the biaxially stretched polyamide film of the base layer can be subjected to heat treatment or humidity conditioning treatment to improve dimensional stability depending on the application. In addition, to improve the adhesion of the film surface, corona treatment, coating treatment, flame treatment, etc., can be performed, and printing and vapor deposition of metals, inorganic oxides, etc. are also possible. As the vapor deposition film formed by vapor deposition, vapor deposition films of aluminum, silicon oxide, aluminum oxide alone or a mixture thereof are preferably used. Furthermore, by coating a protective layer or the like on these vapor deposition films, oxygen barrier properties, etc. can be improved.

[0053] [Sealant layer] The sealant layer is preferably an unstretched polyolefin film, and the unstretched polyolefin film is preferably a film containing a polyethylene-based resin composition and / or a polypropylene-based resin composition.

[0054] When the sealant layer is mainly formed from a polyethylene-based resin composition, examples of the polyethylene-based resin composition include linear low-density polyethylene (LLDPE) and low-density polyethylene (LDPE). The sealant layer may have a single layer structure or a multi-layer structure of two or more layers, and includes at least one layer formed from a polyethylene-based resin composition and may also include layers formed from any other resin. However, the total amount of layers formed from the polyethylene-based resin composition of the present invention in the entire sealant film is preferably 40% by mass or more and 100% by mass or less.

[0055] Linear low-density polyethylene can be produced by a production method such as a high-pressure method, a solution method, or a gas-phase method. Examples of linear low-density polyethylene include copolymers of ethylene and at least one α-olefin having 3 or more carbon atoms. The α-olefin may be any of those generally referred to as α-olefins, and is preferably an α-olefin having 3 to 12 carbon atoms, such as propylene, butene-1, hexene-1, octene-1, or 4-methyl-1-pentene. Examples of copolymers of ethylene and α-olefin include ethylene-hexene-1 copolymer, ethylene-butene-1 copolymer, and ethylene-octene-1 copolymer, with ethylene-hexene copolymer being preferred from the viewpoint of flex pinhole resistance.

[0056] The linear low-density polyethylene may include biomass-derived linear low-density polyethylene, which is polymerized using ethylene derived from plants such as sugarcane and ethylene derived from fossil fuels such as petroleum or plants as part of the raw materials. Biomass-derived linear low-density polyethylene is said to be effective in reducing carbon dioxide emissions and curbing global warming from the viewpoint of carbon neutrality. When biomass-derived linear low-density polyethylene contains biomass-derived ethylene, the content is preferably 50% by mass or more, more preferably 80% by mass or more. A content of 50% or more provides a good carbon dioxide reduction effect. The upper limit is preferably 98%, more preferably 96%. Copolymerization of an α-olefin other than ethylene is preferable from the viewpoint of cold formability, so the content is preferably 98% by mass or less.

[0057] When the sealant layer is formed primarily from a polypropylene-based resin composition, it preferably contains 70 to 95% by mass of polypropylene-based resin and 5 to 30% by mass of linear low-density polyethylene-based resin, at least a portion of which is derived from biomass. The sealant layer may have a single-layer structure or a multi-layer structure of two or more layers. One embodiment includes a structure having a seal layer, a core layer, and a laminate layer, in this order. The seal layer and the laminate layer are located on the surface side of the unstretched polyolefin film, and the core layer is located between them. When the unstretched polyolefin film is used as a laminate for battery packaging, the laminate layer is a layer suitable for bonding a metal foil, and in practice, it is preferably laminated via an adhesive resin. The seal layer is a layer suitable for producing a battery package by heat sealing. This layer structure allows the inclusion of a larger amount of linear low-density polyethylene-based resin derived from biomass while maintaining the excellent heat resistance of the unstretched polypropylene film, which serves as the sealant layer.

[0058] In this case, the polypropylene resin composition constituting the seal layer and the core layer Direct The difference in the content of linear low-density polyethylene is preferably 1 to 28% by mass, more preferably 1 to 23% by mass, even more preferably 1 to 18% by mass, and particularly preferably 1 to 15% by mass. By keeping the difference in content at 28% by mass or less, it is possible to maintain high interlayer strength at the interface between the seal layer and the core layer. In the polypropylene-based resin composition constituting the core layer and the laminate layer, Direct The difference in the content of linear low-density polyethylene is preferably 1 to 28% by mass, more preferably 1 to 23% by mass, even more preferably 1 to 18% by mass, and particularly preferably 1 to 15% by mass. By keeping the difference in content at 28% by mass or less, it is possible to maintain high interlayer strength at the interface between the core layer and the laminate layer.

[0059] The polypropylene resin composition preferably contains a propylene-α-olefin random copolymer. An example of such a copolymer is a copolymer of propylene and at least one α-olefin other than propylene having 2 or 4 to 20 carbon atoms. Examples of such α-olefin monomers having 2 or 4 to 20 carbon atoms include ethylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, and octene-1.

[0060] The propylene-α-olefin random copolymer is preferably made of ethylene in terms of heat sealability. At least one type of copolymer is sufficient, and two or more types can be mixed and used as needed. A particularly suitable copolymer is a propylene-ethylene-butene random copolymer in which the main monomer is propylene and a certain amount of ethylene and butene are copolymerized.

[0061] <Additives> The unstretched polyolefin film may contain an appropriate amount of an antiblocking agent, an antioxidant, an antistatic agent, an antifogging agent, a neutralizing agent, a nucleating agent, a colorant, other additives, an inorganic filler, etc. in any layer as needed, within the scope of not impairing the object of the present invention.

[0062] The unstretched polyolefin film may contain an antiblocking agent. While a single type of antiblocking agent may be used, incorporating two or more types of inorganic particles with different particle sizes and shapes can form complex protrusions even on the uneven surface of the film, resulting in a more effective antiblocking effect. The antiblocking agent to be added is not particularly limited, but inorganic particles such as spherical silica, amorphous silica, zeolite, talc, mica, alumina, hydrotalcite, and aluminum borate, as well as organic particles such as polymethyl methacrylate and ultra-high molecular weight polyethylene, can be added.

[0063] The unstretched polyolefin film may contain an organic lubricant. The inclusion of an organic lubricant improves the film's lubricity and anti-blocking effect, improving the film's handleability. This is thought to be because the organic lubricant bleeds out and is present on the film surface, thereby exerting its lubricating and release effects. Organic lubricants preferably have a melting point above room temperature. Examples of organic lubricants include fatty acid amides and fatty acid esters. Specific examples include oleic acid amide, erucic acid amide, behenic acid amide, ethylene bisoleic acid amide, hexamethylene bisoleic acid amide, and ethylene bisoleic acid amide. While these may be used alone, using two or more of them in combination is preferred, as this allows the lubrication and anti-blocking effects to be maintained even in harsh environments.

[0064] The unstretched polyolefin film may contain an antioxidant, such as a phenolic antioxidant, a phosphite antioxidant, a combination of these, or an antioxidant having both a phenolic and a phosphite skeleton in one molecule. Examples of neutralizing agents include calcium stearate.

[0065] [Non-oriented polyolefin film] The lower limit of the thickness of the unstretched polyolefin film of the sealant layer is preferably 15 μm, more preferably 20 μm, and even more preferably 25 μm. When it is 15 μm or more, heat seal strength and bag rupture resistance are easily obtained. The upper limit of the film thickness is preferably 80 μm, more preferably 70 μm, even more preferably 60 μm, and particularly preferably 50 μm. When it is 80 μm or less, the film does not have too much stiffness and is easy to process, and a suitable laminate for battery packaging is easily produced.

[0066] The haze value of the unstretched polyolefin film is preferably 20.0% or less, more preferably 15.0%, and even more preferably 10.0%. When it is 20.0% or less, visibility of the package is easily obtained. Linear low-density polyethylene is highly crystalline and tends to increase haze, but if it is added within the above-mentioned preferred range, the increase in haze can be suppressed. The lower limit is preferably 1.0%, more preferably 2.0%. When it is 1.0% or more, the film surface is not extremely uneven, so blocking of the inner surface of the package is unlikely to occur.

[0067] The static friction coefficient of the unstretched polyolefin film is preferably 0.70 or less, more preferably 0.50, and even more preferably 0.40. If it is 0.70 or less, the opposite surfaces slide easily when filling the package with food or when opening it, making it easy to open. The lower limit is preferably 0.10 or more, more preferably 0.20 or more, and particularly preferably 0.30. If it is 0.10 or more, the rolled film is less likely to collapse when transported.

[0068] The impact strength of the unstretched polyolefin film is preferably 0.20 J / 15 μm or more, more preferably 0.25 J, and even more preferably 0.30 J. By making it 0.20 J or more, the drop-breakage resistance of the package can be improved. An impact strength of 1.0 J is sufficient. The impact strength is largely dependent on the thickness and molecular orientation of the film.

[0069] The pin puncture strength of the unstretched polyolefin film is preferably 1.0 N or more, more preferably 1.5 N or more, and even more preferably 1.7 N or more. When it is 1.0 μm or more, the pinhole resistance of the laminate is good.

[0070] The planar orientation coefficient of the unstretched polyolefin film is preferably 0.000 or more, more preferably 0.001 or more. The upper limit of the planar orientation of the film is preferably 0.010 or less, more preferably 0.008 or less, and even more preferably 0.006 or less. If it is greater than this, the film may be stretched non-uniformly, resulting in poor thickness uniformity.

[0071] The unstretched polyolefin film preferably contains 3 to 30 mol % of biomass-derived carbon (also called biomass content) based on the total carbon in the unstretched polyolefin film, as determined by radiocarbon (C14) measurement according to ASTM D6866-16.

[0072] [Manufacturing method of unstretched polyolefin film] The non-oriented polyolefin film of the present invention can be produced by, for example, an inflation method or a T-die method, but the T-die method is preferred to improve transparency. The inflation method uses air as a cooling medium, whereas the T-die method uses a cooling roll, making it an advantageous production method for increasing the cooling rate. Increasing the cooling rate can suppress crystallization of the non-oriented sheet, thereby improving transparency.

[0073] [Metal foil layer] Various metal foils such as aluminum and stainless steel can be used for the metal foil layer, with aluminum foil being preferred in terms of moisture resistance, processability such as ductility, and cost. A typical soft aluminum foil can be used as the aluminum foil. Among these, iron-containing aluminum foil is preferred in terms of pinhole resistance and excellent ductility during molding. The iron content in the iron-containing aluminum foil (100% by mass) is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. When the iron content is equal to or greater than the lower limit, the packaging material 1 exhibits excellent pinhole resistance and ductility. When the iron content is 9.0% by mass or less, the packaging material 1 exhibits excellent flexibility. The thickness of the metal foil layer is preferably 9 to 200 μm, more preferably 15 to 100 μm, in terms of barrier properties, pinhole resistance, and processability.

[0074] [Adhesive layer] The adhesive layer is a layer provided to firmly bond the base material layer 1 and the metal layer. The adhesive used in the adhesive layer may be a two-component curing adhesive or a one-component curing adhesive. Furthermore, the adhesive mechanism used to form the adhesive layer 5 is not particularly limited, and may be any of a chemical reaction type, a solvent volatilization type, a hot melt type, a hot pressure type, etc.

[0075] Specific examples of adhesive components that can be used to form the adhesive layer include polyester resins, polyurethane adhesives, epoxy resins, phenolic resins, polyamide resins, polyolefin resins, polyvinyl acetate resins, cellulose adhesives, (meth)acrylic resins, polyimide resins, urea resins, amino resins such as melamine resins, rubbers, silicone resins, etc. These adhesive components may be used alone or in combination of two or more.

[0076] [Base material layer 2] In the laminate for battery packaging of the present invention, a base material layer 2 can be further provided on the surface of the base material layer 1 opposite the metal layer for the purpose of imparting electrolyte resistance, heat resistance, etc. As the layer used for the base material layer 2, a biaxially oriented polyester film such as a biaxially oriented polyethylene terephthalate film or a biaxially oriented polybutylene terephthalate film can be suitably used. Among these, a biaxially oriented polyethylene terephthalate film is preferred from the viewpoints of heat resistance and chemical resistance.

[0077] The polyethylene terephthalate film used as the base layer 2 of the battery packaging laminate of the present invention can be a biaxially oriented polyethylene terephthalate film characterized by being composed of ethylene glycol derived from biomass and dicarboxylic acid units derived from fossil fuels, in addition to the conventionally used polyethylene terephthalate film composed of petroleum-derived raw materials. In particular, the use of biaxially oriented polyethylene terephthalate film, which is characterized by being composed of biomass-derived ethylene glycol and fossil fuel-derived dicarboxylic acid units, is preferred because it improves the biomass content of the laminate and does not affect the increase or decrease in carbon dioxide on the ground, thereby reducing the environmental burden.

[0078] [Battery packaging laminate] The laminate for battery packaging of the present invention has at least a base layer 1, an adhesive layer, a metal layer, and a sealant layer, but a laminate film can also be formed between the base layer and the metal layer, or between the metal layer and the sealant layer, via an adhesive layer, a printed layer, etc. Known lamination methods such as dry lamination and extrusion lamination can be used as the lamination method, and any lamination method may be used.

[0079] The laminate film for packaging batteries preferably contains 2 to 30 mol % of biomass-derived carbon (also called biomass content) based on radiocarbon (C14) measurement according to ASTM D6866-16 relative to the total carbon in the laminate film for packaging batteries. [Example]

[0080] The film was evaluated by the following measurement methods. Unless otherwise specified, measurements were carried out in a measurement room at 23°C and a relative humidity of 65%.

[0081] (1) Film thickness The obtained film was cut into 100 mm lengths in the vertical direction, with 10 layers stacked, and conditioned for at least 2 hours in an environment at a temperature of 23°C and a relative humidity of 65%.The film was then divided into 10 equal parts across the width (for narrow films, the division was made so that the width was wide enough to ensure thickness measurement), and the thickness was measured using a thickness measuring device made by Tester Sangyo.The average value was divided by the number of layers of film to determine the film thickness. The thickness of the A layer was calculated based on the ratio of the resin discharge amounts of the A layer, the B layer, and the C layer.

[0082] (2) Haze value The haze value of the film was measured using a direct reading haze meter manufactured by Toyo Seiki Seisakusho Co., Ltd. in accordance with JIS K7105.

[0083] (3) Biomass ratio The biomass content of the film was determined by radiocarbon (C14) measurement according to ASTM D6866-16 Method B (AMS).

[0084] (4) Heat shrinkage rate The heat shrinkage of the film was measured in both the MD and TD directions using the following formula in accordance with the dimensional change test method described in JIS C2318, except that the test temperature was 160°C and the heating time was 10 minutes. Heat shrinkage rate = [(length before treatment - length after treatment) / length before treatment] x 100 (%)

[0085] (5) Impact strength The impact strength of the film was measured using a film impact tester manufactured by Toyo Seiki Seisakusho, Ltd. The measured value was converted to a value per 15 μm thickness and expressed as J (joules) / 15 μm.

[0086] (6) Degree of plane orientation The sample was taken from the center position in the width direction of the film. The refractive index (nx) in the longitudinal direction of the film and the refractive index (ny) in the width direction of the film were measured using an Abbe refractometer with sodium D line as a light source according to JIS K 7142-1996 Method A, and the degree of planar orientation was calculated using formula (1). Planar orientation degree (ΔP)=(nx+ny) / 2-nz (1)

[0087] (7)Piercing strength The puncture strength of the film was measured in accordance with "2. Testing Methods for Strength, etc." in "Specifications and Standards for Foods, Food Additives, etc., Part 3: Apparatus and Containers / Packaging" (Ministry of Health and Welfare Notification No. 20, 1982) under the Food Sanitation Act. A needle with a tip diameter of 0.7 mm was pierced into the film at a puncture speed of 50 mm / min, and the strength with which the needle penetrated the film was measured and used as the puncture strength. The measurement was carried out at room temperature (23°C), and the puncture strength (unit: N) of the obtained film was divided by the actual thickness of the film to obtain the puncture strength (unit: N / μm).

[0088] (8) Wetting tension The wetting tension of the laminate layer surface was measured in accordance with JIS-K6768 Plastics - Films and Sheets - Wetting Tension Test Method.

[0089] (9) Draw formability The obtained laminate was placed in a die set mold (convex shape 90 mm × 50 mm) and pressed with a press at 23°C to perform drawing. The drawing depth during forming was increased in 0.2 mm increments, and the maximum depth at which the laminate was not damaged was taken as the drawing depth, and it was rated as A to C. Judgment Drawing depth A 8mm or more B: 4mm to less than 8mm C. Less than 4 mm

[0090] [Manufacturing Example 1] <Preparation of biaxially oriented polyamide film (ONY)> (ONY1) Using an apparatus consisting of two extruders and a 380 mm wide co-extrusion T-die, the layers were laminated in a B layer / A layer / B layer configuration using the feed block method, and the molten resin was extruded from the T-die into a film.The film was then cast onto a cooling roll controlled at 20°C and electrostatically adhered to obtain an unstretched film with a thickness of 200 μm.

[0091] The following resin compositions were used for layers A and B: A layer: 97 parts by mass of polyamide 6 (manufactured by Toyobo Co., Ltd., relative viscosity 2.8, melting point 220°C); and Polyamide 11 (manufactured by Arkema, relative viscosity 2.5, melting point 186°C) 3.0 parts by mass B layer: 95 parts by mass of polyamide 6 (manufactured by Toyobo Co., Ltd., relative viscosity 2.8, melting point 220°C); 5.0 parts by mass of polyamide MXD6 (manufactured by Mitsubishi Gas Chemical Co., Inc., relative viscosity 2.1, melting point 237°C); 0.54 parts by mass of porous silica microparticles (manufactured by Fuji Silysia Chemical Ltd., average particle diameter 2.0 μm, pore volume 1.6 ml / g); and Fatty acid bisamide (ethylene bisstearic acid amide, manufactured by Kyoeisha Chemical Co., Ltd.) 0.15 parts by mass

[0092] The feed block configuration and extrusion rate of the extruder were adjusted so that the total thickness of the biaxially oriented polyamide film was 15 μm, with the thickness of the base layer (layer A) being 12 μm and the thickness of the front and back surface layers (layer B) being 1.5 μm each.

[0093] The resulting unstretched film was fed into a roll-type stretching machine and stretched 1.73 times in the MD direction at 80°C using the differential speed of the rolls, followed by a further stretch of 1.85 times at 70°C. This uniaxially stretched film was then continuously fed into a tenter-type stretching machine, preheated at 110°C, and stretched 1.2 times in the TD direction at 120°C, 1.7 times at 130°C, and 2.0 times at 160°C. It was then heat-set at 218°C and relaxed 7% at 218°C. The surface to be dry-laminated with a linear low-density polyethylene film was then corona-discharge-treated to obtain a biaxially stretched polyamide film. The evaluation results of the resulting biaxially stretched polyamide film are shown in Table 1.

[0094] (ONY2~ONY15) A biaxially stretched film was obtained in the same manner as for ONY1, except that the raw resin composition and film-forming conditions, such as the heat setting temperature, were changed as shown in Table 1. The evaluation results of the obtained biaxially stretched film are shown in Table 1. However, with ONY13, the molten resin could not be stably extruded from the T-die into a film shape, and a homogeneous unstretched film could not be obtained, so biaxial stretching was not possible.

[0095] The polyamide resins containing at least a portion of biomass-derived raw materials, namely polyamide 410, polyamide 610, and polyamide 1010, were as follows: Polyamide 410: (DSM, ECOPaXX Q150-E, melting point 250°C) Polyamide 610: (Arkema, RilsanS SMNO, melting point 222°C) Polyamide 1010: (Arkema, Rilsan™ TMNO, melting point 202°C)

[0096] [Table 1A]

[0097] [Table 1B]

[0098] [Table 1C]

[0099] [Manufacturing Example 2] <Production of non-oriented polyolefin film (CPP)> (CPP1) The raw materials were prepared based on the resin composition and proportions of each layer shown in Table 2. The preparations for each layer shown in Table 2 were taken as 100 parts by weight. 360 ppm of behenic acid amide was added to the sealing layer as an organic lubricant, and 2000 ppm of silica with an average particle size of 4 μm was added as an inorganic anti-blocking agent in a masterbatch. 2700 ppm of behenic acid amide was added to the core layer as an organic lubricant in a masterbatch.

[0100] (Materials used in the sealing layer) PP-1: Sumitomo Chemical Co., Ltd. propylene-ethylene-butene random copolymer FL6745A (MFR 6.0 g / 10 min, melting point 130°C) Silica particles: Amorphous silica KMP130-4 (average particle size 4 μm) manufactured by Shin-Etsu Chemical Co., Ltd. Organic lubricant: Behenic acid amide BNT-22H manufactured by Nippon Fine Chemical Co., Ltd.

[0101] (Raw materials used in the core layer) PP-2: Propylene-ethylene-butene random copolymer FL8115A (MFR 7.0 g / 10 min, melting point 148°C) manufactured by Sumitomo Chemical Co., Ltd. LL-1: Braskem SLH218 ethylene-hexene copolymer (plant-derived linear low-density polyethylene) (MFR 2.3 g / min, density 916 kg / m³, melting point 126°C) Organic lubricant: Behenic acid amide BNT-22H manufactured by Nippon Fine Chemical Co., Ltd.

[0102] (Materials used in the laminate layer) PP-2: Propylene-ethylene-butene random copolymer FL8115A (MFR 7.0 g / 10 min, melting point 148°C) manufactured by Sumitomo Chemical Co., Ltd. LL-1: Braskem SLH218 ethylene-hexene copolymer (plant-derived linear low-density polyethylene) (MFR 2.3 g / min, density 916 kg / m³, melting point 126°C)

[0103] The mixed raw materials for the core layer were extruded in a three-stage single-screw extruder with a screw diameter of 90 mm, and the mixed raw materials for the seal layer and laminate layer were extruded in three-stage single-screw extruders with diameters of 65 mm and 45 mm, respectively, in the order of seal layer / core layer / laminate layer.The materials were then extruded into a T-slot die with a width of 800 mm, a two-stage preland, and a curved step shape to ensure uniform flow of the molten resin within the die, at an exit temperature of 230°C.The thickness ratios of the laminate layer / intermediate layer / heat seal layer were 25% / 50% / 25%, respectively.

[0104] The molten resin sheet emerging from the die was cooled on a cooling roll at 35°C to obtain an unstretched polyolefin film with a thickness of 30 μm. During cooling on the cooling roll, both ends of the film on the cooling roll were fixed with air nozzles, and the entire width of the molten resin sheet was pressed against the cooling roll with an air knife. At the same time, a vacuum chamber was activated to prevent air entrapment between the molten resin sheet and the cooling roll. Both ends of the air nozzles were installed in series in the direction of film travel. The die was surrounded by a sheet to prevent wind from blowing on the molten resin sheet. The suction port of the vacuum chamber was aligned with the direction of travel of the extruded sheet.

[0105] The surface of the film laminate layer was subjected to corona treatment (power density 20 W·min / m 2 The film was produced at a film production speed of 20 m / min. The edges of the produced film were trimmed and the film was wound into a roll. The evaluation results of the CPP1 film are shown in Table 2.

[0106] (CPP2) As CPP2, a non-stretched polypropylene film P1146 (thickness 70 μm) manufactured by Toyobo Co., Ltd. was used.

[0107] [Table 2]

[0108] [Examples and Comparative Examples] <Preparation of laminate for battery packaging> An ester adhesive was used, prepared by mixing 33.6 parts by mass of a base agent (TM569, manufactured by Toyo-Morton Co., Ltd.), 4.0 parts by mass of a curing agent (CAT10L, manufactured by Toyo-Morton Co., Ltd.), and 62.4 parts by mass of ethyl acetate, so that the biaxially oriented polyamide film obtained in Production Example 1 was laminated on one side of an aluminum foil (8079 material, thickness 40 μm) and the unstretched polyolefin film obtained in Production Example 2 was laminated on the other side of the aluminum foil, with the adhesive applied at a rate of 3.0 g / m. 2The laminate was then dry laminated. The biaxially oriented polyamide film and unoriented polyolefin film were all laminated with the longitudinal and transverse directions aligned. The laminate was wound up and kept at 40°C for 3 days, after which the battery packaging laminate was evaluated.

[0109] When a biaxially oriented polyester film was laminated on the outside of the biaxially oriented polyamide film as the base layer 2, the biaxially oriented polyester film and the biaxially oriented polyamide film were first laminated in the same manner as above, and then laminated on one side of the aluminum foil. Next, a non-oriented polyolefin film was laminated on the opposite side of the aluminum foil. As the base layer 2, the following film was used. (PET1) Biaxially oriented polyethylene terephthalate film (thickness 16 μm) using petroleum-derived terephthalic acid as the dicarboxylic acid component and petroleum-derived ethylene glycol as the diol component. (PET2) Biaxially oriented polyethylene terephthalate film (thickness 16 μm) using petroleum-derived terephthalic acid as the dicarboxylic acid component and biomass-derived ethylene glycol as the diol component.

[0110] Laminates for battery packaging were produced and evaluated using the combinations shown in Table 3. The results are shown in Table 3.

[0111] [Table 3]

[0112] As shown in Table 3, the laminates for battery packaging of the Examples were excellent in cold formability even when the biomass content was increased.

[0113] On the other hand, the laminate of Comparative Example 1 uses only conventional petroleum-derived films, so the biomass content is 0%, and the environmental load cannot be reduced. In addition, in the laminate of Comparative Example 2, the lamination strength of the biaxially stretched film used was low, and therefore good cold formability was not obtained. In the laminate of Comparative Example 3, the biaxially oriented polyamide film used has a low biomass content, and therefore the effect of reducing the environmental load is insufficient. In the laminate of Comparative Example 4, the heat treatment temperature during film formation of the biaxially stretched polyamide film was high, and although the dimensional stability was good, the puncture strength of the film was reduced, resulting in reduced cold formability. In Comparative Example 5, all films, including the base layer 2, are derived from petroleum, so the biomass content is 0%, and the environmental load cannot be reduced. The heat seal strength was poor.

[0114] From the above, the laminate for packaging batteries of the present invention has excellent cold formability and puncture resistance, and can be suitably used as a carbon-neutral laminate for packaging batteries using raw materials derived from biomass.

Claims

1. a laminate for packaging a battery, comprising at least a base material layer 1, an adhesive layer, a metal foil layer, and a sealant layer laminated in this order, wherein the base material layer 1 is a biaxially oriented polyamide film satisfying the following (a) to (c); the sealant layer is an unstretched polyolefin film, which is an unstretched polyolefin film containing 70 to 95% by mass of a polypropylene-based resin and 5 to 30% by mass of a linear low-density polyethylene-based resin at least part of which is derived from biomass; the sealant layer has a configuration comprising a seal layer, a core layer, and a laminate layer in this order; the difference in the content of linear low-density polyethylene between the polypropylene-based resin compositions constituting the seal layer and the core layer is 1 to 28% by mass, and the difference in the content of linear low-density polyethylene between the polypropylene-based resin compositions constituting the core layer and the laminate layer is 1 to 28% by mass; (a) Thickness: 8 to 30 μm (b) The content of carbon derived from biomass as determined by radiocarbon (C14) measurement is 1 to 30% of the total carbon in the substrate layer 1. (c) A puncture strength measured according to JIS Z 1707 method of 0.7 N / μm or more

2. 2. The battery packaging laminate according to claim 1, wherein the base layer 1 is a biaxially oriented polyamide film consisting of a single layer formed from a resin composition containing polyamide 6 and a polyamide at least part of which is derived from biomass.

3. 2. The laminate for battery packaging according to claim 1, wherein the base material layer 1 is a biaxially stretched polyamide film consisting of at least two layers: a layer (layer A) formed from a resin composition containing polyamide 6 and a polyamide at least part of which is derived from biomass, and a layer (layer B) formed from a resin composition containing polyamide 6 and not containing a polyamide at least part of which is derived from biomass.

4. 4. The laminate for battery packaging according to claim 2, wherein the polyamide at least a part of which is derived from biomass is at least one polyamide selected from the group consisting of polyamide 11, polyamide 410, polyamide 610, and polyamide 1010.

5. 5. The laminate for battery packaging according to claim 1, wherein the content of biomass-derived carbon in the sealant layer as determined by radiocarbon (C14) measurement is 3 to 30% of the total carbon in the sealant layer.

6. 6. The laminate for battery packaging according to claim 1, wherein a base material layer 2 having a thickness of 10 to 30 μm is further laminated on the surface of the base material layer 1 opposite to the metal foil layer.

7. 7. The laminate for battery packaging according to claim 6, wherein the base layer 2 is a biaxially oriented polyester film.

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