JP2023167264A - Sheath material for power storage device and method of manufacturing the same, and power storage device - Google Patents

Abstract

To provide a novel sheath material for a power storage device, the sheath martial including polyester originated from biomass.SOLUTION: A sheath material for a power storage device includes a laminate in which a base material layer, a barrier layer, and a heat-fused resin layer are laminated at least in the order from the outermost to the innermost layer. The base material layer includes at least one resin layer. The resin layer contains a resin composition containing polyester A containing a mixture of a diol unit and a dicarboxylic acid unit. In the polyester A, the diol unit is alkylene glycol originated from biomass and the dicarboxylic acid unit is dicarboxylic acid originated from fossil fuel.SELECTED DRAWING: None

Description

The present disclosure relates to an exterior material for a power storage device, a method for manufacturing the same, and a power storage device.

Conventionally, various types of power storage devices have been developed, and in all power storage devices, an exterior material has become an essential member for sealing power storage device elements such as electrodes and electrolytes. Conventionally, metal exterior materials have been frequently used as exterior materials for power storage devices.

On the other hand, in recent years, as electric vehicles, hybrid electric vehicles, personal computers, cameras, mobile phones, and the like have become more sophisticated, power storage devices are required to have a variety of shapes, as well as to be thinner and lighter. However, metal exterior materials for power storage devices, which have been widely used in the past, have the disadvantage that it is difficult to keep up with the diversification of shapes, and there is also a limit to the reduction in weight.

Therefore, in recent years, film-like materials in which a base material layer, a barrier layer, and a heat-fusible resin layer are sequentially laminated have been developed as exterior materials for power storage devices that can be easily processed into various shapes and can be made thinner and lighter. A laminate has been proposed (see, for example, Patent Document 1).

JP2008-287971A Special Publication No. 2002-512304

In the exterior material for an electricity storage device constructed from a film-like laminate as described above, a polyester film is sometimes used for the base material layer.

Polyester is obtained by polycondensing diol units and dicarboxylic acid units. For example, polyethylene terephthalate (hereinafter sometimes abbreviated as PET) is obtained by esterifying ethylene glycol and terephthalic acid as raw materials. After that, it is produced by polycondensation reaction. These raw materials are produced from petroleum, which is a fossil resource; for example, ethylene glycol is industrially produced from ethylene, and terephthalic acid is industrially produced from xylene.

In recent years, with increasing calls for building a recycling-oriented society, there is a desire to move away from fossil fuels in the materials field as well as energy, and the use of biomass is attracting attention. Biomass is an organic compound that is photosynthesized from carbon dioxide and water, and by using it, it becomes carbon dioxide and water again, so it is a so-called carbon-neutral renewable energy. In recent years, the practical use of biomass plastics made from these biomass raw materials has progressed rapidly, and attempts are also being made to produce polyester, which is a general-purpose polymer material, from these biomass raw materials.

For example, as a polyester using a biomass raw material, a polyester consisting of isosorbide, which is one of the biomass raw materials, terephthalic acid, and ethylene glycol has been proposed (Patent Document 2).

In addition, biomass ethanol obtained by fermenting starch and sugars obtained from plants such as corn and sugarcane with microorganisms has been put into practical use, and it is possible to industrially produce ethylene glycol from this biomass ethanol via ethylene. It has also been successful.

The main objective of the present disclosure is to provide a novel exterior material for power storage devices that uses polyester containing raw materials derived from biomass.

The inventors of the present disclosure have conducted extensive studies to solve the above problems. As a result, in the exterior material for a power storage device, which is composed of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-fusible resin layer, the diol unit is biomass-derived alkylene glycol, and the diol unit is biomass-derived alkylene glycol; We have discovered that by using polyester whose acid units are dicarboxylic acids derived from fossil fuels in the base layer, it is possible to obtain an exterior material for a power storage device that has good properties such as moldability.

The present disclosure was completed through further studies based on such new findings. That is, the present disclosure provides inventions of the following aspects.
Consisting of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-fusible resin layer,
The base material layer includes at least one resin layer,
The resin layer is composed of a resin composition containing polyester A consisting of diol units and dicarboxylic acid units,
The polyester A is an exterior material for a power storage device, wherein the diol unit is an alkylene glycol derived from biomass, and the dicarboxylic acid unit is a dicarboxylic acid derived from fossil fuel.

According to the present disclosure, it is possible to provide a novel exterior material for a power storage device that uses polyester containing a raw material derived from biomass. Furthermore, by using biomass-derived polyester as the exterior material for power storage devices, the amount of fossil fuel used can be significantly reduced, and the environmental burden can also be reduced. Further, according to the present disclosure, it is also possible to provide a method for manufacturing the exterior material for a power storage device, and an energy storage device using the exterior material for a power storage device.

It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for electricity storage devices of this indication. It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for electricity storage devices of this indication. It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for electricity storage devices of this indication. It is a schematic diagram showing an example of the cross-sectional structure of the exterior material for electricity storage devices of this indication. It is a schematic diagram for demonstrating the method of accommodating an electrical storage device element in the package formed of the exterior material for electrical storage devices of this indication.

The exterior material for a power storage device of the present disclosure is composed of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-fusible resin layer, and the base material layer includes at least one resin layer. The resin layer is composed of a resin composition containing polyester A consisting of a diol unit and a dicarboxylic acid unit, in which the diol unit is an alkylene glycol derived from biomass and the dicarboxylic acid unit is a fossil fuel-derived dicarboxylic acid. The exterior material for power storage devices of the present disclosure is a novel exterior material for power storage devices that uses polyester containing raw materials derived from biomass, and has excellent properties such as moldability required for exterior materials for power storage devices.

Hereinafter, the exterior material for a power storage device of the present disclosure will be described in detail. In this specification, the numerical range indicated by "~" means "more than" or "less than". For example, the expression 2 to 15 mm means 2 mm or more and 15 mm or less. In the numerical ranges described step by step in the present disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the upper limit or lower limit of another numerical range described step by step. Further, the upper limit value and the upper limit value, the upper limit value and the lower limit value, or the lower limit value and the lower limit value, which are described separately, may be combined to form a numerical range. Furthermore, in the numerical ranges described in this disclosure, the upper limit or lower limit described in a certain numerical range may be replaced with the value shown in the Examples.

1. Laminated structure of exterior material for power storage device The exterior material 10 for power storage device of the present disclosure is a laminate including a base material layer 1, a barrier layer 3, and a heat-fusible resin layer 4 in this order, for example, as shown in FIG. It consists of In the exterior material 10 for a power storage device, the base layer 1 is the outermost layer, and the heat-fusible resin layer 4 is the innermost layer. When assembling a power storage device using the power storage device exterior material 10 and the power storage device element, heat-seal the peripheral edges with the heat-sealable resin layers 4 of the power storage device exterior material 10 facing each other. A power storage device element is accommodated in the space formed by. In the laminate forming the exterior material 10 for a power storage device according to the present disclosure, with the barrier layer 3 as a reference, the heat-fusible resin layer 4 side is on the inner side than the barrier layer 3, and the base material layer 1 side is on the inner side than the barrier layer 3. It is outside.

For example, as shown in FIGS. 2 to 4, the exterior material 10 for a power storage device includes a layer between the base material layer 1 and the barrier layer 3, as necessary, for the purpose of increasing the adhesion between these layers. It may also have an adhesive layer 2. Further, as shown in FIGS. 3 and 4, for example, an adhesive layer 5 may be formed between the barrier layer 3 and the heat-fusible resin layer 4 for the purpose of increasing the adhesiveness between these layers. It may have. Further, as shown in FIG. 4, a surface coating layer 6 or the like may be provided on the outside of the base material layer 1 (on the side opposite to the heat-fusible resin layer 4 side), if necessary.

The thickness of the laminate that constitutes the exterior material 10 for power storage devices is not particularly limited, but from the viewpoint of cost reduction, energy density improvement, etc., it is, for example, 190 μm or less, preferably about 180 μm or less, about 155 μm or less, about 120 μm or less can be mentioned. In addition, from the viewpoint of maintaining the function of the exterior material for an energy storage device to protect the energy storage device elements, the thickness of the laminate constituting the exterior material 10 for an energy storage device is preferably about 35 μm or more, about 45 μm or more, or about 45 μm or more. Examples include 60 μm or more. Further, preferred ranges of the laminate constituting the exterior material 10 for power storage devices include, for example, approximately 35 to 190 μm, approximately 35 to 180 μm, approximately 35 to 155 μm, approximately 35 to 120 μm, approximately 45 to 190 μm, and approximately 45 to 180 μm. , about 45 to 155 μm, about 45 to 120 μm, about 60 to 190 μm, about 60 to 180 μm, about 60 to 155 μm, and about 60 to 120 μm, and particularly preferably about 60 to 155 μm.

In the exterior material 10 for a power storage device, the base material layer 1, the adhesive layer 2 provided as necessary, the barrier layer 3, and the The ratio of the total thickness of the adhesive layer 5 provided, the heat-fusible resin layer 4, and the surface coating layer 6 provided as necessary is preferably 90% or more, more preferably 95% or more, More preferably, it is 98% or more. As a specific example, when the exterior material 10 for a power storage device of the present disclosure includes a base layer 1, an adhesive layer 2, a barrier layer 3, an adhesive layer 5, and a heat-fusible resin layer 4, the exterior material for a power storage device The ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting the material 10 is preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. Further, even when the exterior material 10 for an energy storage device of the present disclosure is a laminate including a base layer 1, an adhesive layer 2, a barrier layer 3, and a heat-fusible resin layer 4, the exterior material for an energy storage device The ratio of the total thickness of each of these layers to the thickness (total thickness) of the laminate constituting 10 is, for example, 80% or more, preferably 90% or more, more preferably 95% or more, and still more preferably 98% or more. I can do it.

2. Each layer forming the exterior material for power storage device [base material layer 1]
In the present disclosure, the base material layer 1 is a layer provided for the purpose of exhibiting a function as a base material of an exterior material for a power storage device. Base material layer 1 is located on the outer layer side of the exterior material for a power storage device.

In the present disclosure, the base material layer 1 includes at least one resin layer. The resin layer is made of a resin composition containing polyester A consisting of diol units and dicarboxylic acid units. Polyester A will be explained in detail below.

(Polyester A)
In polyester A, the diol unit is an alkylene glycol derived from biomass, and the dicarboxylic acid unit is a dicarboxylic acid derived from fossil fuel. That is, polyester A is a polyester using raw materials derived from biomass. Polyester A is obtained by polycondensation reaction using biomass-derived alkylene glycol as the diol unit and fossil fuel-derived dicarboxylic acid as the dicarboxylic acid unit.

Biomass-derived alkylene glycol is made from alcohol produced from biomass (eg, biomass ethanol). For example, biomass-derived ethylene glycol can be obtained by converting biomass ethanol into ethylene glycol via ethylene oxide using a conventionally known method. Moreover, commercially available biomass ethylene glycol may be used, and for example, biomass ethylene glycol commercially available from India Glycol Corporation can be suitably used.

Examples of alkylene glycols derived from biomass include aliphatic diols derived from biomass and having a lower limit of carbon number of 2 or more and an upper limit of usually 10 or less, preferably 6 or less. Specifically, biomass-derived ethylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,6-hexamethylene glycol, decamethylene glycol, 1,4-butanediol, and 1,4-cyclohexanediol Examples include methanol. These may be used alone or as a mixture of two or more. Among these, biomass-derived ethylene glycol, 1,4-butanediol, 1,3-propylene glycol, and 1,4-cyclohexanedimethanol are preferred, and biomass-derived ethylene glycol is particularly preferred. For example, if biomass-derived ethylene glycol is used as a raw material for polyester, polyethylene terephthalate can be obtained using the biomass-derived raw material. Furthermore, when biomass-derived 1,4-butanediol is used as a raw material for polyester, polybutylene terephthalate can be obtained using a biomass-derived raw material.

Dicarboxylic acid derived from fossil fuels is used as the dicarboxylic acid unit of the polyester. As the dicarboxylic acid, aromatic dicarboxylic acids, aliphatic dicarboxylic acids, and derivatives thereof can be used without limitation. Examples of aromatic dicarboxylic acids include terephthalic acid and isophthalic acid, and examples of derivatives of aromatic dicarboxylic acids include lower alkyl esters of aromatic dicarboxylic acids, specifically methyl esters, ethyl esters, propyl esters, and butyl esters. Examples include esters. Among these, terephthalic acid is preferred, and as the aromatic dicarboxylic acid derivative, dimethyl terephthalate is preferred.

Examples of aliphatic dicarboxylic acids include oxalic acid, succinic acid, glutaric acid, adipic acid, sebacic acid, dodecanedioic acid, dimer acid, and cyclohexanedicarboxylic acid, which usually have 2 to 40 carbon atoms. chain or alicyclic dicarboxylic acids. Further, as derivatives of aliphatic dicarboxylic acids, lower alkyl esters such as methyl ester, ethyl ester, propyl ester, and butyl ester of the above aliphatic dicarboxylic acids, and cyclic acid anhydrides of the above aliphatic dicarboxylic acids such as succinic anhydride may be used. Can be mentioned. Among these, adipic acid, succinic acid, dimer acid, or mixtures thereof are preferred, and those containing succinic acid as a main component are particularly preferred. As the aliphatic dicarboxylic acid derivative, methyl esters of adipic acid and succinic acid, or mixtures thereof are more preferred.

These dicarboxylic acids can be used alone or in combination of two or more.

Polyester A may be a copolymerized polyester in which a copolymerized component is added as a third component in addition to the diol component and dicarboxylic acid component described above. Specific examples of copolymerization components include bifunctional oxycarboxylic acids, trifunctional or more polyhydric alcohols, trifunctional or more polycarboxylic acids and/or their anhydrides, and trifunctional or more functional polyhydric alcohols to form a crosslinked structure. At least one type of polyfunctional compound selected from the group consisting of oxycarboxylic acids having higher than functional functions is mentioned. Among these copolymerization components, bifunctional and/or trifunctional or higher functional oxycarboxylic acids are particularly preferably used because copolymerized polyesters with a high degree of polymerization tend to be easily produced. Among these, the use of trifunctional or higher functional oxycarboxylic acids is most preferable because polyester with a high degree of polymerization can be easily produced in a very small amount without using a chain extender described later.

Moreover, the polyester A may be a high molecular weight polyester obtained by chain extension (coupling) of these copolymerized polyesters. As a chain extender, a chain extender such as a carbonate compound or a diisocyanate compound can be used, but the amount thereof is usually determined based on 100 mol% of the total monomer units constituting polyester A. is usually 10 mol% or less, preferably 5 mol% or less, more preferably 3 mol% or less.

Specifically, carbonate compounds include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, ethylene carbonate, diamyl carbonate, dicyclohexyl Examples include carbonate. In addition, carbonate compounds derived from hydroxy compounds such as phenols and alcohols and composed of the same or different hydroxy compounds can be used.

Specific examples of the diisocyanate compound include 2,4-tolylene diisocyanate, a mixture of 2,4-tolylene diisocyanate and 2,6-tolylene diisocyanate, diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, and xylene diisocyanate. Known diisocyanates such as diisocyanate, hydrogenated xylylene diisocyanate, hexamethylene diisocyanate, and isophorone diisocyanate can be mentioned.

Polyester A can be obtained by a conventionally known method of polycondensing the diol units and dicarboxylic acid units described above. Specifically, after performing the esterification reaction and/or transesterification reaction between the above-mentioned dicarboxylic acid component and diol component, a general method of melt polymerization in which a polycondensation reaction is performed under reduced pressure, and an organic solvent It can be produced by a known solution heating dehydration condensation method using.

The amount of diol used when producing polyester A is substantially equimolar to 100 moles of the dicarboxylic acid or its derivative, but generally, it is used in esterification and/or transesterification reaction and/or polycondensation reaction. Since there is distillation of the liquid, an excess of 0.1 to 20 mol % is used.

Further, the polycondensation reaction is preferably carried out in the presence of a polymerization catalyst. The timing of adding the polymerization catalyst is not particularly limited as long as it is before the polycondensation reaction, and it may be added at the time of charging the raw materials or at the start of pressure reduction.

Examples of the polymerization catalyst generally include compounds containing metal elements from Groups 1 to 14 of the periodic table, excluding hydrogen and carbon. Specifically, at least one metal selected from the group consisting of titanium, zirconium, tin, antimony, cerium, germanium, zinc, cobalt, manganese, iron, aluminum, magnesium, calcium, strontium, sodium, and potassium. Compounds containing organic groups, such as carboxylates, alkoxy salts, organic sulfonates, or β-diketonate salts, as well as inorganic compounds such as the metal oxides and halides mentioned above, and mixtures thereof. Among these, metal compounds containing titanium, zirconium, germanium, zinc, aluminum, magnesium, and calcium, and mixtures thereof are preferred, and titanium compounds, zirconium compounds, and germanium compounds are particularly preferred. Furthermore, since the polymerization rate increases when the catalyst is in a molten or dissolved state during polymerization, it is preferably a compound that is liquid during polymerization or dissolves in the ester low polymer or polyester.

The titanium compound is preferably a tetraalkyl titanate, specifically, tetra-n-propyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-t-butyl titanate, tetraphenyl titanate, tetracyclohexyl titanate, tetra- Mention may be made of benzyl titanate and mixed titanates thereof. In addition, titanium (oxy)acetylacetonate, titanium tetraacetylacetonate, titanium (diisoprooxide) acetylacetonate, titanium bis(ammonium lactate) dihydroxide, titanium bis(ethylacetoacetate) diisopropoxide, titanium (triethanolaminate) ) Isopropoxide, polyhydroxy titanium stearate, titanium lactate, titanium triethanolaminate, butyl titanate dimer, etc. are also suitably used. Furthermore, titanium oxide and composite oxides containing titanium and silicon are also suitably used. Among these, tetra-n-propyl titanate, tetraisopropyl titanate and tetra-n-butyl titanate, titanium (oxy)acetylacetonate, titanium tetraacetylacetonate, titanium bis(ammonium lactate) dihydroxide, polyhydroxytitanium stearate. , titanium lactate, butyl titanate dimer, titanium oxide, titania/silica composite oxide (for example, product name: C-94 manufactured by Acordis Industrial Fibers) are preferred, and in particular, tetra-n-butyl titanate, polyhydroxy titanium stearate, titanium Preferred are (oxy)acetylacetonate, titanium tetraacetylacetonate, and titania/silica composite oxide (eg, product name: C-94 manufactured by Acordis Industrial Fibers).

Specific examples of zirconium compounds include zirconium tetraacetate, zirconium acetate hydroxide, zirconium tris(butoxy)stearate, zirconyl diacetate, zirconium oxalate, zirconyl oxalate, zirconium potassium oxalate, and polyhydroxyzirconium. Mention may be made of stearate, zirconium ethoxide, zirconium tetra-n-propoxide, zirconium tetraisopropoxide, zirconium tetra-n-butoxide, zirconium tetra-t-butoxide, zirconium tributoxyacetylacetonate and mixtures thereof. Furthermore, zirconium oxide or a composite oxide containing zirconium and silicon, for example, may be used. Among these, zirconyl diacetate, zirconium tris(butoxy) stearate, zirconium tetraacetate, zirconium acetate hydroxide, zirconium ammonium oxalate, zirconium potassium oxalate, polyhydroxyzirconium stearate, zirconium tetra-n-propoxy Preferred are zirconium tetraisopropoxide, zirconium tetra-n-butoxide, and zirconium tetra-t-butoxide.

Specific examples of germanium compounds include inorganic germanium compounds such as germanium oxide and germanium chloride, and organic germanium compounds such as tetraalkoxygermanium. In terms of price and availability, germanium oxide, tetraethoxygermanium, tetrabutoxygermanium, and the like are preferred, and germanium oxide is particularly preferred.

When using a metal compound as a polymerization catalyst, the lower limit of the amount of metal relative to polyester A to be produced is usually 5 ppm or more, preferably 10 ppm or more, and the upper limit is usually 30,000 ppm or less, preferably 1,000 ppm or less. , more preferably 250 ppm or less, particularly preferably 130 ppm or less. If the amount of catalyst used is too large, it is not only economically disadvantageous but also reduces the thermal stability of the polymer, whereas if it is too small, the polymerization activity decreases and the resulting degradation of the polymer occurs during polymer production. becomes more likely to be induced. As for the amount of catalyst used here, a method of reducing the amount of catalyst used is a preferred embodiment because the lower the amount used, the lower the amount of terminal carboxyl groups in the polyester A produced.

The reaction temperature of the esterification reaction and/or transesterification reaction between the dicarboxylic acid component and the diol component is usually in the range of 150 to 260°C, and the reaction atmosphere is usually an inert gas atmosphere such as nitrogen or argon. . Further, the reaction pressure is usually normal pressure to 10 kPa. Further, the reaction time is usually about 1 hour to 10 hours.

In the above manufacturing process, a chain extender (coupling agent) may be added to the reaction system. After the completion of polycondensation, the chain extender is added to the reaction system in a uniform molten state without a solvent, and is reacted with the polyester obtained by polycondensation.

High molecular weight polyesters using these chain extenders (coupling agents) can be produced using known techniques. After the completion of polycondensation, the chain extender is added to the reaction system in a uniform molten state without a solvent, and reacted with the polyester obtained by polycondensation. Specifically, a polyester obtained by catalytically reacting a diol and a dicarboxylic acid, whose terminal group substantially has a hydroxyl group, and whose mass average molecular weight (Mw) is 20,000 or more, preferably 40,000 or more. By reacting the prepolymer with the chain extender, a polyester resin having a higher molecular weight can be obtained. If the prepolymer has a mass average molecular weight of 20,000 or more, it can be used even under severe conditions such as in a molten state by using a small amount of coupling agent, and will not be affected by residual catalyst, so it will not form a gel during the reaction. , high molecular weight polyester A can be produced.

After the obtained polyester A is solidified, it may be subjected to solid phase polymerization, if necessary, in order to further increase the degree of polymerization or to remove oligomers such as cyclic trimers. Specifically, after polyester is chipped and dried, the polyester is pre-crystallized by heating at a temperature of 100 to 180°C for about 1 to 8 hours, and then inert at a temperature of 190 to 230°C. This is carried out by heating for 1 to several tens of hours under gas flow or reduced pressure.

The intrinsic viscosity of the polyester A obtained as described above (measured with an orthochlorophenol solution at 35°C) is preferably 0.5 dl/g to 1.5 dl/g, more preferably 0.6 dl/g. /g to 1.2 dl/g. If the intrinsic viscosity is less than 0.5 dl/g, the tear strength and other mechanical properties required of a polyester film used as a base layer of an exterior material for a power storage device may be insufficient. On the other hand, if the intrinsic viscosity exceeds 1.5 dl/g, productivity in the raw material manufacturing process and film forming process will be impaired.

In the manufacturing process of polyester A, or to the manufactured polyester A, various additives may be added to the extent that its properties are not impaired. Erasers, deodorants, flame retardants, weathering agents, antistatic agents, yarn friction reducers, mold release agents, antioxidants, ion exchange agents, coloring pigments, etc. can be added. These additives are preferably added in an amount of 5% by mass or more, more preferably 5 to 50% by mass, and still more preferably 5 to 20% by mass, based on the entire resin composition forming the resin layer.

From the viewpoint of more preferably exhibiting the effects of the present disclosure, the content of polyester A in the resin composition forming the resin layer is preferably 50% by mass or more, more preferably 50 to 95% by mass, and even more preferably 50% by mass. ~90% by mass.

(Polyester B)
In the present disclosure, in addition to polyester A, the resin layer of base layer 1 may further include polyester B, which is polyester made from recycled raw materials (hereinafter also referred to as recycled polyester). . Polyester B is a polyester obtained by recycling a resin product made of a polyester in which the diol unit is a fossil fuel-derived diol or a biomass-derived alkylene glycol, and the dicarboxylic acid unit is a fossil fuel-derived dicarboxylic acid. Polyester B is a product made of a polyester resin obtained by polycondensation reaction using a diol derived from fossil fuel or ethylene glycol derived from biomass as the diol unit and a dicarboxylic acid derived from fossil fuel as the dicarboxylic acid unit. , is a polyester obtained by recycling.

Even if the diol unit and dicarboxylic acid unit are both made from fossil fuel-derived raw materials, the resin that is the source of recycled polyester (that is, the polyester resin before recycling) is not biomass polyester as described above. Good too.

Fossil fuel-derived diols used in the resin that is the basis of recycled polyester include aliphatic diols, aromatic diols, and derivatives thereof, and those used as diol units of conventional polyesters are preferably used. be able to. The aliphatic diol is not particularly limited as long as it is an aliphatic or alicyclic compound having two OH groups, but the lower limit of the number of carbon atoms is 2 or more, and the upper limit is usually 10 or less, preferably 6. The following aliphatic diols may be mentioned. Specific examples include ethylene glycol, 1,3-propylene glycol, neopentyl glycol, 1,6-hexamethylene glycol, decamethylene glycol, 1,4-butanediol, and 1,4-cyclohexanedimethanol. It will be done. These may be used alone or as a mixture of two or more. Among these, ethylene glycol, 1,4-butanediol, 1,3-propylene glycol and 1,4-cyclohexanedimethanol are preferred, and ethylene glycol is particularly preferred.

From the viewpoint of more preferably exhibiting the effects of the present disclosure, the content of polyester B in the resin composition forming the resin layer is preferably 50% by mass or less, more preferably 5 to 45% by mass, and even more preferably 5% by mass. ~40% by mass.

The resin layer in the base material layer 1 of the present disclosure preferably has a biomass-derived carbon content of 10 to 19% based on radiocarbon (C14) measurement, based on the total carbon in the resin composition. Since carbon dioxide in the atmosphere contains C14 at a certain rate (105.5 pMC), the C14 content in plants that grow by taking in atmospheric carbon dioxide, such as corn, is also around 105.5 pMC. It is known. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the proportion of C14 contained in all carbon atoms in polyester, the proportion of carbon derived from biomass can be calculated. In the present invention, the biomass-derived carbon content Pbio is defined as follows, where the C14 content in polyester is PC14.
Pbio (%) = PC14/105.5×100

Taking polyethylene terephthalate as an example, polyethylene terephthalate is a polymerization of ethylene glycol containing 2 carbon atoms and terephthalic acid containing 8 carbon atoms in a molar ratio of 1:1, so only biomass-derived ethylene glycol can be used. When Pbio is used, the biomass-derived carbon content Pbio in the polyester is 20%. In the present invention, the content of biomass-derived carbon as measured by radiocarbon (C14) is preferably 10 to 19% based on the total carbon in the resin composition. If the biomass-derived carbon content in the resin composition is less than 10%, the effect as a carbon offset material will be poor. On the other hand, as mentioned above, it is preferable that the biomass-derived carbon content in the resin composition be close to 20%, but due to problems in the manufacturing process and physical properties of polyester films, recycled polyester as described above is used in the resin. The actual upper limit is 18%, since it is preferable to include additives.

The resin layer containing polyester A may be, for example, a resin film formed of resin, or may be formed by applying resin. The resin film may be an unstretched film or a stretched film. Examples of the stretched film include uniaxially stretched film and biaxially stretched film, with biaxially stretched film being preferred. Examples of the stretching method for forming a biaxially stretched film include a sequential biaxial stretching method, an inflation method, and a simultaneous biaxial stretching method. Examples of methods for applying the resin include roll coating, gravure coating, and extrusion coating.

The resin layer containing polyester A had the following tensile properties (MD and TD test pieces (width 15 mm, length 150 mm); It is preferable to have properties of tensile strength at break (MPa), tensile elongation at break (%), and stress at 5% elongation (kMPa).

The tensile breaking strength A (MPa) of the MD test piece of the resin layer containing polyester A is preferably about 210 MPa or more, more preferably about 220 MPa or more, furthermore about 230 MPa or more, and preferably about 270 MPa or less, More preferably about 260 MPa or less, further about 250 MPa or less, and preferable ranges include about 210 to 270 MPa, about 210 to 260 MPa, about 210 to 250 MPa, about 220 to 270 MPa, about 220 to 260 MPa, about 220 to 250 MPa, and about 230 MPa. ~270 MPa, approximately 230 to 260 MPa, and approximately 230 to 250 MPa.

Further, the tensile breaking strength A (MPa) of the TD test piece of the resin layer containing polyester A is preferably about 230 MPa or more, more preferably about 240 MPa or more, further preferably about 250 MPa or more, and preferably about 300 MPa. Below, it is more preferably about 290 MPa or less, further about 280 MPa or less, and the preferable range is about 230 to 300 MPa, about 230 to 290 MPa, about 230 to 280 MPa, about 240 to 300 MPa, about 240 to 290 MPa, and about 240 to 280 MPa. , about 250 to 300 MPa, about 250 to 290 MPa, and about 250 to 280 MPa.

The tensile elongation at break (%) of the MD test piece of the resin layer containing polyester A is preferably about 80% or more, more preferably about 90% or more, and even more preferably about 100% or more, and preferably about 150% or less, more preferably about 140% or less, further about 130% or less, and preferable ranges include about 80 to 150%, about 80 to 140%, about 80 to 130%, about 90 to 150%, and about 90%. Examples include about 140%, about 90 to 130%, about 100 to 150%, about 100 to 140%, and about 100 to 130%.

The tensile elongation at break (%) of the TD test piece of the resin layer containing polyester A is preferably about 70% or more, more preferably about 80% or more, and even more preferably about 90% or more, and preferably about 130% or less, more preferably about 120% or less, further about 110% or less, and preferable ranges include about 70 to 130%, about 70 to 120%, about 70 to 110%, about 80 to 130%, and about 80%. Examples include about ~120%, about 80-110%, about 90-130%, about 90-120%, and about 90-110%.

The stress B (MPa) at 5% elongation of the MD test piece of the resin layer containing polyester A is preferably about 90 MPa or more, more preferably about 100 MPa or more, further preferably about 105 MPa or more, and preferably about 130 MPa or less, more preferably about 120 MPa or less, further about 110 MPa or less, and preferable ranges are about 90 to 130 MPa, about 90 to 120 MPa, about 90 to 110 MPa, about 100 to 130 MPa, about 100 to 120 MPa, and 100 to 110 MPa. Examples include about 105 to 130 MPa, about 105 to 120 MPa, and about 105 to 110 MPa.

The stress B (kMPa) at 5% elongation of the TD test piece of the resin layer containing polyester A is preferably about 90 MPa or more, more preferably about 95 MPa or more, further preferably about 100 MPa or more, and preferably about 115 MPa or less, more preferably about 110 MPa or less, further about 100 MPa or less, and preferred ranges are about 90 to 115 MPa, about 90 to 110 MPa, about 90 to 100 MPa, about 95 to 115 MPa, about 95 to 110 MPa, and 95 to 100 MPa. Examples include about 100 to 115 MPa, about 100 to 110 MPa, and about 100 to 100 MPa.

Further, the ratio (A/B) of the tensile strength at break A (MPa) to the stress B (kMPa) at 5% elongation of the MD test piece of the resin layer containing polyester A is preferably about 1.5 or more, More preferably about 2.0 or more, further about 2.5 or more, and preferably about 3.5 or less, more preferably about 3.0 or less, and further about 2.5 or less, and the preferred range is , around 1.5 to 3.5, around 1.5 to 3.0, around 1.5 to 2.5, around 2.0 to 3.5, around 2.0 to 3.0, around 2.0 Examples include about 2.5, about 2.5 to 3.5, and about 2.5 to 3.0.

Further, the ratio (A/B) of tensile strength at break A (MPa) to stress B (kMPa) at 5% elongation of the TD test piece of the resin layer containing polyester A is preferably about 1.5 or more, More preferably about 2.0 or more, further about 2.5 or more, and preferably about 4.0 or less, more preferably about 3.5 or less, and still more preferably about 3.0 or less, and the preferred range is , about 1.5-4.0, about 1.5-3.5, about 1.5-3.0, about 2.0-4.0, about 2.0-3.5, 2.0- Examples include about 3.0, about 2.5 to 4.0, about 2.5 to 3.5, and about 2.5 to 3.0.

<Tensile properties>
For the resin layer containing polyester A, test pieces were cut out from each of MD and TD to a width of 15 mm and a length of 150 mm. ), and the strength and elongation of the test piece is measured using a tensile tester (for example, an automatic film strength and elongation measuring device "Tensilon AMF/RTA-100" manufactured by Orientech Co., Ltd.). In addition, the F5 value (tensile strength when the film is stretched by 5%) in MD and TD is measured.

In addition, in accordance with JIS C-2318:2020, an MD test piece (width 15 mm, length 150 mm, length direction of MD test piece) of the resin layer containing polyester A was tested in accordance with JIS C-2318:2020. The heat shrinkage rate when placed in an environment of 150° C. for 30 minutes is preferably about 1.0% or more, more preferably about 1.5% or more, and even more preferably about 2.0% or more. is about 3.5% or less, more preferably about 3.0% or less, furthermore about 2.5% or less, and the preferable range is about 1.0 to 3.5%, 1.0 to 3.0%. %, about 1.0 to 2.5%, about 1.5 to 3.5%, about 1.5 to 3.0%, about 1.5 to 2.5%, 2.0 to 3.5 %, about 2.0 to 3.0%, and about 2.0 to 2.5%.

In addition, regarding the TD test piece (width 15 mm, length 150 mm, length direction of the TD test piece is TD) of the resin layer containing polyester A, in accordance with JIS C-2318:2020, The heat shrinkage rate when placed in an environment of 150° C. for 30 minutes is preferably about 0.1% or more, more preferably about 0.3% or more, and even more preferably about 0.5% or more. is about 1.5% or less, more preferably about 1.0% or less, furthermore about 0.5% or less, and the preferable range is about 0.1 to 1.5%, 0.1 to 1.0%. %, about 0.1 to 0.5%, about 0.3 to 1.5%, about 0.3 to 1.0%, about 0.3 to 0.5%, 0.5 to 1.5 %, about 0.5 to 1.0%.

<Heat shrinkage rate>
Regarding the resin layer containing polyester A, test pieces (15 mm in width and 150 mm in length) were cut out from each of MD and TD, with the length direction of the MD test piece being MD, and the length direction of the TD test piece being cut out from each of the MD and TD. is TD) is placed in a heating oven at 150°C and heat-treated at 150°C for 30 minutes in accordance with JIS C-2318:2020, and the heat shrinkage rate is measured.

In addition to the resin layer containing polyester A, the base layer 1 may further include another resin layer. Examples of resins forming other resin layers include resins that do not contain polyester A, such as polyester, polyamide, polyolefin, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, and modified resins of these resins. Things can be mentioned. Further, the resin forming the base material layer 1 may be a copolymer of these resins or a modified product of the copolymer. Furthermore, a mixture of these resins may be used.

Among these, preferable examples of the resin forming the other resin layer include polyester and polyamide that do not contain polyester A.

Specific examples of polyesters that do not contain polyester A include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyesters that do not use biomass-derived raw materials. These polyesters may be used alone or in combination of two or more.

Specific examples of polyamides include aliphatic polyamides such as nylon 6, nylon 66, nylon 610, nylon 12, nylon 46, and copolymers of nylon 6 and nylon 66; terephthalic acid and/or isophthalic acid; Hexamethylenediamine-isophthalic acid-terephthalic acid copolyamides, polyamide MXD6 (polymethacrylic acid), etc. containing structural units derived from nylon 6I, nylon 6T, nylon 6IT, nylon 6I6T (I represents isophthalic acid, T represents terephthalic acid), etc. Aromatic polyamides such as polyamide PACM6 (polybis(4-aminocyclohexyl)methaneadipamide); and lactam components and isocyanate components such as 4,4'-diphenylmethane-diisocyanate. Polyamides such as copolymerized polyamides, polyesteramide copolymers and polyetheresteramide copolymers which are copolymers of copolymerized polyamides and polyesters or polyalkylene ether glycols; and copolymers of these are exemplified. These polyamides may be used alone or in combination of two or more.

The other resin layer may be, for example, a resin film made of resin, or may be formed by applying resin. The resin film may be an unstretched film or a stretched film. Examples of the stretched film include uniaxially stretched film and biaxially stretched film, with biaxially stretched film being preferred. Examples of the stretching method for forming a biaxially stretched film include a sequential biaxial stretching method, an inflation method, and a simultaneous biaxial stretching method. Examples of methods for applying the resin include roll coating, gravure coating, and extrusion coating.

The base material layer 1 may be a single layer of a resin layer containing polyester A, or two or more layers (two or more resin layers containing polyester A, or a resin layer containing polyester A and another resin layer). (two or more layers). When the base material layer 1 is composed of two or more layers, the base material layer 1 may be a laminate in which resin films are laminated with an adhesive or the like, or a resin film may be coextruded to form two or more layers. It may also be a laminate of resin films. Further, a laminate of two or more resin films formed by coextruding resins may be used as the base layer 1 without being stretched, or may be uniaxially or biaxially stretched as the base layer 1.

In the base layer 1, specific examples of a laminate of two or more resin films include a laminate of a polyester film and a nylon film, a laminate of two or more polyester films, and preferably a stretched nylon film. A laminate of a stretched polyester film and a laminate of two or more layers of stretched polyester films are preferred. For example, when the base material layer 1 is a laminate of two layers of resin films, a laminate of a polyester resin film and a polyester resin film, or a laminate of a polyester resin film and a polyamide resin film is preferable, and a laminate of a polyethylene terephthalate film and a polyethylene terephthalate film is preferable. A laminate of films or a laminate of polyethylene terephthalate film and nylon film is more preferred. In addition, since polyester resin is difficult to discolor when an electrolyte adheres to its surface, for example, when the base layer 1 is a laminate of two or more resin films, the polyester resin film is the same as the base layer 1. Preferably, it is located in the outermost layer.

When the base material layer 1 is a laminate of two or more layers of resin films, the two or more layers of resin films may be laminated via an adhesive. Preferred adhesives include those similar to the adhesives exemplified in adhesive layer 2 described below. The method for laminating two or more layers of resin films is not particularly limited, and any known method can be used, such as a dry lamination method, a sandwich lamination method, an extrusion lamination method, a thermal lamination method, etc., and preferably a dry lamination method. One example is the lamination method. When laminating by dry lamination, it is preferable to use a polyurethane adhesive as the adhesive. At this time, the thickness of the adhesive is, for example, about 2 to 5 μm. Alternatively, an anchor coat layer may be formed on a resin film and laminated thereon. Examples of the anchor coat layer include the same adhesive as the adhesive layer 2 described below. At this time, the thickness of the anchor coat layer is, for example, about 0.01 to 1.0 μm.

Further, a lubricant, a flame retardant, an anti-blocking agent, an antioxidant, a light stabilizer, a tackifier, an antistatic agent, etc. may be present on at least one of the surface and inside of the base layer 1. These may be used alone or in combination of two or more.

In the present disclosure, it is preferable that a lubricant be present on the surface of the base material layer 1 from the viewpoint of improving the moldability of the exterior material for a power storage device. The lubricant is not particularly limited, but preferably includes an amide lubricant. Specific examples of amide lubricants include saturated fatty acid amides, unsaturated fatty acid amides, substituted amides, methylolamides, saturated fatty acid bisamides, unsaturated fatty acid bisamides, fatty acid ester amides, aromatic bisamides, and the like. Specific examples of saturated fatty acid amides include lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, hydroxystearic acid amide, and the like. Specific examples of unsaturated fatty acid amides include oleic acid amide and erucic acid amide. Specific examples of substituted amides include N-oleyl palmitic acid amide, N-stearyl stearic acid amide, N-stearyl oleic acid amide, N-oleyl stearic acid amide, N-stearyl erucic acid amide, and the like. Furthermore, specific examples of methylolamide include methylolstearamide and the like. Specific examples of saturated fatty acid bisamides include methylene bisstearamide, ethylene biscapric acid amide, ethylene bislauric acid amide, ethylene bisstearic acid amide, ethylene bishydroxystearic acid amide, ethylene bisbehenic acid amide, and hexamethylene bis stearic acid amide. Examples include acid amide, hexamethylene bisbehenic acid amide, hexamethylene hydroxystearic acid amide, N,N'-distearyl adipic acid amide, N,N'-distearyl sebacic acid amide, and the like. Specific examples of unsaturated fatty acid bisamides include ethylene bisoleic acid amide, ethylene biserucic acid amide, hexamethylene bisoleic acid amide, N,N'-dioleyladipic acid amide, and N,N'-dioleyl sebacic acid amide. Examples include. Specific examples of fatty acid ester amides include stearamide ethyl stearate. Specific examples of aromatic bisamides include m-xylylene bisstearamide, m-xylylene bishydroxystearamide, and N,N'-distearylisophthalic acid amide. One type of lubricant may be used alone, or two or more types may be used in combination.

When a lubricant is present on the surface of the base layer 1, its amount is not particularly limited, but is preferably about 3 mg/m ² or more, more preferably about 4 to 15 mg/m ² , and even more preferably 5 to 14 mg. / ^m2 .

The lubricant present on the surface of the base layer 1 may be one obtained by exuding a lubricant contained in the resin constituting the base layer 1, or a lubricant coated on the surface of the base layer 1. It's okay.

The thickness of the base material layer 1 is not particularly limited as long as it functions as a base material, but may be, for example, about 3 to 50 μm, preferably about 10 to 35 μm. When the base layer 1 is a laminate of two or more layers of resin films, the thickness of the resin films constituting each layer is preferably about 2 to 25 μm.

[Adhesive layer 2]
In the exterior material for a power storage device according to the present disclosure, the adhesive layer 2 is a layer provided between the base material layer 1 and the barrier layer 3 as necessary for the purpose of increasing the adhesiveness between the two.

The adhesive layer 2 is formed of an adhesive capable of bonding the base material layer 1 and the barrier layer 3 together. The adhesive used to form the adhesive layer 2 is not limited, but may be any one of a chemical reaction type, a solvent volatilization type, a heat melt type, a heat pressure type, and the like. Further, it may be a two-component curing adhesive (two-component adhesive), a one-component curing adhesive (one-component adhesive), or a resin that does not involve a curing reaction. Furthermore, the adhesive layer 2 may be a single layer or a multilayer.

Specifically, the adhesive components contained in the adhesive include polyesters such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polyethylene isophthalate, and copolymerized polyester; polyether; polyurethane; epoxy resin; Phenol resins; polyamides such as nylon 6, nylon 66, nylon 12, and copolymerized polyamides; polyolefin resins such as polyolefins, cyclic polyolefins, acid-modified polyolefins, and acid-modified cyclic polyolefins; polyvinyl acetate; cellulose; (meth)acrylic resins; Examples include polyimide; polycarbonate; amino resins such as urea resin and melamine resin; rubbers such as chloroprene rubber, nitrile rubber, and styrene-butadiene rubber; and silicone resins. These adhesive components may be used alone or in combination of two or more. Among these adhesive components, polyurethane adhesives are preferred. Further, the adhesive strength of these adhesive component resins can be increased by using an appropriate curing agent in combination. The curing agent is selected from among polyisocyanates, polyfunctional epoxy resins, oxazoline group-containing polymers, polyamine resins, acid anhydrides, etc., depending on the functional groups of the adhesive component.

Examples of the polyurethane adhesive include a polyurethane adhesive that includes a first part containing a polyol compound and a second part containing an isocyanate compound. Preferred examples include two-component curing polyurethane adhesives in which a polyol such as a polyester polyol, a polyether polyol, or an acrylic polyol is used as a first part and an aromatic or aliphatic polyisocyanate is used as a second part. Further, examples of the polyurethane adhesive include a polyurethane adhesive containing a polyurethane compound prepared by reacting a polyol compound and an isocyanate compound in advance, and an isocyanate compound. Further, examples of the polyurethane adhesive include a polyurethane adhesive containing a polyurethane compound prepared by reacting a polyol compound and an isocyanate compound in advance, and a polyol compound. Further, examples of the polyurethane adhesive include, for example, a polyurethane adhesive obtained by curing a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance with moisture in the air or the like. As the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in the side chain in addition to the hydroxyl group at the end of the repeating unit. Examples of the second agent include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate. (MDI), naphthalene diisocyanate (NDI), and the like. Also included are polyfunctional isocyanate modified products of one or more of these diisocyanates. It is also possible to use multimers (for example trimers) as the polyisocyanate compound. Such multimers include adducts, biurets, nurates, and the like. Since the adhesive layer 2 is formed of a polyurethane adhesive, the exterior material for the power storage device has excellent electrolyte resistance, and peeling of the base material layer 1 is suppressed even if the electrolyte adheres to the side surface. .

Further, the adhesive layer 2 may contain other components such as colorants, thermoplastic elastomers, tackifiers, fillers, etc., as long as they do not impede adhesiveness. Since the adhesive layer 2 contains the coloring agent, the exterior material for the electricity storage device can be colored. As the colorant, known colorants such as pigments and dyes can be used. Moreover, only one type of coloring agent may be used, or two or more types of coloring agents may be used in combination.

The type of pigment is not particularly limited as long as it does not impair the adhesiveness of the adhesive layer 2. Examples of organic pigments include azo pigments, phthalocyanine pigments, quinacridone pigments, anthraquinone pigments, dioxazine pigments, indigothioindigo pigments, perinone-perylene pigments, isoindolenine pigments, and benzimidazolone pigments. Examples of the pigment include carbon black-based, titanium oxide-based, cadmium-based, lead-based, chromium oxide-based, and iron-based pigments, and in addition, mica (mica) fine powder, fish scale foil, and the like.

Among the colorants, carbon black is preferable, for example, in order to make the exterior of the power storage device exterior black.

The average particle diameter of the pigment is not particularly limited, and may be, for example, about 0.05 to 5 μm, preferably about 0.08 to 2 μm. Note that the average particle diameter of the pigment is the median diameter measured by a laser diffraction/scattering particle diameter distribution measuring device.

The pigment content in the adhesive layer 2 is not particularly limited as long as the exterior material for the electricity storage device is colored, and is, for example, about 5 to 60% by mass, preferably 10 to 40% by mass.

The thickness of the adhesive layer 2 is not particularly limited as long as the base layer 1 and the barrier layer 3 can be bonded together, but is, for example, about 1 μm or more and about 2 μm or more. Further, the thickness of the adhesive layer 2 is, for example, about 10 μm or less, about 5 μm or less. Further, preferable ranges for the thickness of the adhesive layer 2 include about 1 to 10 μm, about 1 to 5 μm, about 2 to 10 μm, and about 2 to 5 μm.

[Barrier layer 3]
In the exterior material for a power storage device, the barrier layer 3 is a layer that prevents at least moisture from entering.

Examples of the barrier layer 3 include a metal foil, a vapor deposited film, and a resin layer having barrier properties. Examples of the vapor-deposited film include a metal vapor-deposited film, an inorganic oxide vapor-deposited film, and a carbon-containing inorganic oxide vapor-deposited film, and examples of the resin layer include polyvinylidene chloride, polymers mainly composed of chlorotrifluoroethylene (CTFE), and tetrafluoroethylene. Examples include fluorine-containing resins such as polymers containing fluoroethylene (TFE) as a main component, polymers having a fluoroalkyl group, and polymers containing fluoroalkyl units as a main component, and ethylene vinyl alcohol copolymers. Further, examples of the barrier layer 3 include a resin film provided with at least one of these vapor-deposited films and a resin layer. A plurality of barrier layers 3 may be provided. It is preferable that the barrier layer 3 includes a layer made of a metal material. Specific examples of the metal material constituting the barrier layer 3 include aluminum alloy, stainless steel, titanium steel, steel plate, etc. When used as metal foil, it includes at least one of aluminum alloy foil and stainless steel foil. It is preferable.

From the perspective of improving the formability of the exterior material for power storage devices, the aluminum alloy foil is preferably a soft aluminum alloy foil made of, for example, annealed aluminum alloy, and from the perspective of further improving the formability. Therefore, an aluminum alloy foil containing iron is preferable. In the aluminum alloy foil containing iron (100% by mass), the iron content is preferably 0.1 to 9.0% by mass, more preferably 0.5 to 2.0% by mass. When the iron content is 0.1% by mass or more, it is possible to obtain an exterior material for a power storage device that has better formability. By having an iron content of 9.0% by mass or less, it is possible to obtain an exterior material for a power storage device that has more excellent flexibility. Examples of the soft aluminum alloy foil include an aluminum alloy having a composition specified by JIS H4160:1994 A8021H-O, JIS H4160:1994 A8079H-O, JIS H4000:2014 A8021P-O, or JIS H4000:2014 A8079P-O. One example is foil. Further, silicon, magnesium, copper, manganese, etc. may be added as necessary. Further, softening can be performed by annealing treatment or the like.

Examples of the stainless steel foil include austenitic, ferritic, austenite-ferritic, martensitic, and precipitation hardening stainless steel foils. Furthermore, from the viewpoint of providing an exterior material for a power storage device with excellent formability, the stainless steel foil is preferably made of austenitic stainless steel.

Specific examples of the austenitic stainless steel constituting the stainless steel foil include SUS304, SUS301, SUS316L, etc. Among these, SUS304 is particularly preferred.

The thickness of the barrier layer 3 is not particularly limited as long as it can at least function as a barrier layer for inhibiting the infiltration of moisture, and is not particularly limited as long as it is 40 μm or more. The thickness of the barrier layer is preferably about 45 μm or more, more preferably about 50 μm or more, even more preferably about 55 μm or more, and preferably about 200 μm or less, more preferably about 150 μm or less, and still more preferably about 100 μm or less. More preferably, it is about 65 μm or less, and preferable ranges include about 40 to 200 μm, about 40 to 150 μm, about 40 to 100 μm, about 40 to 65 μm, about 45 to 200 μm, about 45 to 150 μm, about 45 to 100 μm, Examples include about 45 to 65 μm, about 50 to 200 μm, about 50 to 150 μm, about 50 to 100 μm, about 50 to 65 μm, about 55 to 200 μm, about 55 to 150 μm, about 55 to 100 μm, and about 55 to 65 μm.

Moreover, when the barrier layer 3 is a metal foil, it is preferable that at least the surface opposite to the base material layer is provided with a corrosion-resistant film in order to prevent dissolution and corrosion. The barrier layer 3 may be provided with a corrosion-resistant coating on both sides. Here, the corrosion-resistant film refers to, for example, hydrothermal conversion treatment such as boehmite treatment, chemical conversion treatment, anodizing treatment, plating treatment with nickel or chromium, or corrosion prevention treatment such as applying a coating agent to the surface of the barrier layer. A thin film that provides corrosion resistance (for example, acid resistance, alkali resistance, etc.) to the barrier layer. Specifically, the corrosion-resistant film refers to a film that improves the acid resistance of the barrier layer (acid-resistant film), a film that improves the alkali resistance of the barrier layer (alkali-resistant film), and the like. As the treatment for forming a corrosion-resistant film, one type of treatment may be performed or a combination of two or more types may be performed. Furthermore, it is possible to have not only one layer but also multiple layers. Furthermore, among these treatments, hydrothermal conversion treatment and anodization treatment are treatments in which the surface of the metal foil is dissolved with a treatment agent to form a metal compound with excellent corrosion resistance. Note that these treatments may be included in the definition of chemical conversion treatment. Further, when the barrier layer 3 includes a corrosion-resistant film, the barrier layer 3 includes the corrosion-resistant film.

Corrosion-resistant coatings are used to prevent delamination between the barrier layer (for example, aluminum alloy foil) and the base material layer during the molding of exterior materials for power storage devices, and to prevent delamination by hydrogen fluoride generated by the reaction between electrolyte and moisture. , prevents the dissolution and corrosion of the barrier layer surface, especially when the barrier layer is an aluminum alloy foil, and prevents the aluminum oxide present on the barrier layer surface from dissolving and corroding, and the adhesion (wettability) of the barrier layer surface. It shows the effect of preventing delamination between the base material layer and the barrier layer during heat sealing and the delamination between the base material layer and the barrier layer during molding.

Various types of corrosion-resistant coatings are known that are formed by chemical conversion treatment, and mainly include at least one of phosphates, chromates, fluorides, triazinethiol compounds, and rare earth oxides. Examples include corrosion-resistant coatings containing. Examples of chemical conversion treatments using phosphates and chromates include chromic acid chromate treatment, phosphoric acid chromate treatment, phosphoric acid-chromate treatment, and chromate treatment. Examples of the compound include chromium nitrate, chromium fluoride, chromium sulfate, chromium acetate, chromium oxalate, chromium diphosphate, chromic acid acetylacetate, chromium chloride, potassium chromium sulfate, and the like. Further, examples of phosphorus compounds used in these treatments include sodium phosphate, potassium phosphate, ammonium phosphate, and polyphosphoric acid. Examples of the chromate treatment include etching chromate treatment, electrolytic chromate treatment, coating type chromate treatment, and coating type chromate treatment is preferred. In this coating-type chromate treatment, at least the inner layer side of the barrier layer (for example, aluminum alloy foil) is first coated using a well-known method such as an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, an acid activation method, etc. Degrease treatment is performed using a treatment method, and then metal phosphates such as Cr (chromium) phosphate, Ti (titanium) phosphate, Zr (zirconium) phosphate, and Zn (zinc) phosphate are applied to the degreased surface. Treatment liquids whose main components are salts and mixtures of these metal salts, treatment liquids whose main components are nonmetallic phosphoric acid salts and mixtures of these nonmetallic salts, or combinations of these with synthetic resins, etc. This is a process in which a treatment liquid consisting of a mixture is applied by a well-known coating method such as a roll coating method, a gravure printing method, or a dipping method, and then dried. Various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents can be used as the treatment liquid, and water is preferable. In addition, the resin component used at this time includes polymers such as phenolic resins and acrylic resins, and aminated phenol polymers having repeating units represented by the following general formulas (1) to (4) are used. Examples include chromate treatment. In addition, in the aminated phenol polymer, the repeating units represented by the following general formulas (1) to (4) may be contained alone or in any combination of two or more. Good too. The acrylic resin must be polyacrylic acid, acrylic acid methacrylate copolymer, acrylic acid maleic acid copolymer, acrylic acid styrene copolymer, or derivatives thereof such as sodium salt, ammonium salt, or amine salt. is preferred. Particularly preferred are polyacrylic acid derivatives such as ammonium salts, sodium salts, or amine salts of polyacrylic acid. In the present disclosure, polyacrylic acid refers to a polymer of acrylic acid. Further, the acrylic resin is also preferably a copolymer of acrylic acid and dicarboxylic acid or dicarboxylic anhydride, such as ammonium salt, sodium salt, Or it is also preferable that it is an amine salt. Only one type of acrylic resin may be used, or a mixture of two or more types may be used.

In the general formulas (1) to (4), X represents a hydrogen atom, a hydroxy group, an alkyl group, a hydroxyalkyl group, an allyl group or a benzyl group. Further, R ¹ and R ² are each the same or different and represent a hydroxy group, an alkyl group, or a hydroxyalkyl group. In general formulas (1) to ( ⁴ ), ^the alkyl group represented by Examples include straight chain or branched alkyl groups having 1 to 4 carbon atoms such as tert-butyl group. Furthermore, examples of the hydroxyalkyl group represented by X, R ¹ and R ² include hydroxymethyl group, 1-hydroxyethyl group, 2-hydroxyethyl group, 1-hydroxypropyl group, 2-hydroxypropyl group, Straight chain or branched chain with 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 Examples include alkyl groups. In the general formulas (1) to (4), the alkyl groups and hydroxyalkyl groups represented by X, R ¹ and R ² may be the same or different. In general formulas (1) to (4), X is preferably a hydrogen atom, a hydroxy group or a hydroxyalkyl group. The number average molecular weight of the aminated phenol polymer having repeating units represented by general formulas (1) to (4) is preferably about 500 to 1,000,000, and preferably about 1,000 to 20,000, for example. More preferred. Aminated phenol polymers can be produced, for example, by polycondensing a phenol compound or a naphthol compound with formaldehyde to produce a polymer consisting of repeating units represented by the above general formula (1) or general formula (3), and then adding formaldehyde to the polymer. and amine (R ¹ R ² NH) to introduce a functional group (-CH ₂ NR ¹ R ² ) into the polymer obtained above. Aminated phenol polymers may be used alone or in combination of two or more.

Another example of a corrosion-resistant film is a film formed by a coating-type corrosion-preventing treatment in which a coating agent containing at least one selected from the group consisting of a rare earth element oxide sol, an anionic polymer, and a cationic polymer is applied. Examples include thin films that are The coating agent may further contain phosphoric acid or a phosphate salt, a crosslinking agent for crosslinking the polymer. The rare earth element oxide sol includes rare earth element oxide fine particles (for example, particles with an average particle size of 100 nm or less) dispersed in a liquid dispersion medium. Examples of rare earth element oxides include cerium oxide, yttrium oxide, neodymium oxide, and lanthanum oxide, with cerium oxide being preferred from the viewpoint of further improving adhesion. The rare earth element oxides contained in the corrosion-resistant film can be used alone or in combination of two or more. As the liquid dispersion medium for the rare earth element oxide sol, various solvents such as water, alcohol solvents, hydrocarbon solvents, ketone solvents, ester solvents, and ether solvents can be used, with water being preferred. Examples of the cationic polymer include polyethyleneimine, an ionic polymer complex consisting of a polymer containing polyethyleneimine and a carboxylic acid, a primary amine-grafted acrylic resin in which a primary amine is graft-polymerized onto an acrylic main skeleton, polyallylamine or its derivatives. , aminated phenol, etc. are preferred. The anionic polymer is preferably poly(meth)acrylic acid or a salt thereof, or a copolymer containing (meth)acrylic acid or a salt thereof as a main component. Further, it is preferable that the crosslinking agent is at least one selected from the group consisting of a compound having a functional group such as an isocyanate group, a glycidyl group, a carboxyl group, or an oxazoline group, and a silane coupling agent. Moreover, it is preferable that the phosphoric acid or phosphate is a condensed phosphoric acid or a condensed phosphate.

An example of a corrosion-resistant film is to coat fine particles of barium sulfate or metal oxides such as aluminum oxide, titanium oxide, cerium oxide, and tin oxide in phosphoric acid on the surface of the barrier layer. Examples include those formed by performing baking treatment at temperatures above .degree.

The corrosion-resistant film may have a laminated structure in which at least one of a cationic polymer and an anionic polymer is further laminated, if necessary. Examples of the cationic polymer and anionic polymer include those mentioned above.

Note that the composition of the corrosion-resistant film can be analyzed using, for example, time-of-flight secondary ion mass spectrometry.

The amount of the corrosion-resistant film formed on the surface of the barrier layer 3 in the chemical conversion treatment ^is not particularly limited. is, for example, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, in terms of chromium, the phosphorus compound is, for example, about 0.5 to 50 mg, preferably about 1.0 to 40 mg, in terms of phosphorus, and the aminated phenol polymer. It is desirable that the content is, for example, about 1.0 to 200 mg, preferably about 5.0 to 150 mg.

The thickness of the corrosion-resistant film is not particularly limited, but from the viewpoint of the cohesive force of the film and the adhesion with the barrier layer and the heat-fusible resin layer, it is preferably about 1 nm to 20 μm, more preferably 1 nm to 100 nm. More preferably, it is about 1 nm to 50 nm. The thickness of the corrosion-resistant film can be measured by observation using a transmission electron microscope, or by a combination of observation using a transmission electron microscope and energy dispersive X-ray spectroscopy or electron beam energy loss spectroscopy. Analysis of the composition of the corrosion-resistant film using time-of-flight secondary ion mass spectrometry reveals that, for example, secondary ions consisting of Ce, P, and O (for example, at least one of Ce ₂ PO ₄ ⁺ , CePO ₄ ^- , etc.) peaks derived from secondary ions (for example, at least one of CrPO ₂ ⁺ and CrPO ₄ ^- ) made of Cr, P, and O are detected.

Chemical conversion treatment involves applying a solution containing a compound used to form a corrosion-resistant film to the surface of the barrier layer using a bar coating method, roll coating method, gravure coating method, dipping method, etc., and then changing the temperature of the barrier layer. This is done by heating to a temperature of about 70 to 200°C. Furthermore, before the barrier layer is subjected to the chemical conversion treatment, the barrier layer may be previously subjected to a degreasing treatment using an alkali dipping method, an electrolytic cleaning method, an acid cleaning method, an electrolytic acid cleaning method, or the like. By performing the degreasing treatment in this manner, it becomes possible to perform the chemical conversion treatment on the surface of the barrier layer more efficiently. In addition, by using an acid degreasing agent in which a fluorine-containing compound is dissolved in an inorganic acid for degreasing treatment, it is possible to not only degrease the metal foil but also form passive metal fluoride. In such cases, only degreasing treatment may be performed.

[Thermofusible resin layer 4]
In the exterior material for a power storage device of the present disclosure, the heat-fusible resin layer 4 corresponds to the innermost layer, and has a function of thermally fusing the heat-fusible resin layers to each other and sealing the power storage device element during assembly of the power storage device. This is a layer (sealant layer) that exhibits the following properties.

The resin constituting the heat-fusible resin layer 4 is not particularly limited as long as it can be heat-fusible, but resins containing a polyolefin skeleton such as polyolefin and acid-modified polyolefin are preferred. The fact that the resin constituting the heat-fusible resin layer 4 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography-mass spectrometry, or the like. Furthermore, when the resin constituting the heat-fusible resin layer 4 is analyzed by infrared spectroscopy, it is preferable that a peak derived from maleic anhydride be detected. For example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, peaks derived from maleic anhydride are detected at wave numbers around 1760 cm ^-1 and around 1780 cm ^-1 wave numbers. When the heat-fusible resin layer 4 is a layer composed of maleic anhydride-modified polyolefin, a peak derived from maleic anhydride is detected when measured by infrared spectroscopy. However, if the degree of acid modification is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

The heat-fusible resin layer 4 preferably contains a resin containing a polyolefin skeleton as a main component, more preferably contains a polyolefin as a main component, and even more preferably contains polypropylene as a main component. . Here, the main component means that the content of the resin components contained in the heat-fusible resin layer 4 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably means that the resin component is 80% by mass or more, more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, even more preferably 99% by mass or more. For example, the heat-fusible resin layer 4 containing polypropylene as a main component means that the content of polypropylene among the resin components contained in the heat-fusible resin layer 4 is, for example, 50% by mass or more, preferably 60% by mass. % or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, even more preferably 90% by mass or more, even more preferably 95% by mass or more, even more preferably 98% by mass or more, even more preferably 99% by mass or more. It means that.

Specifically, the polyolefins include polyethylenes such as low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene; ethylene-α olefin copolymers; homopolypropylene, block copolymers of polypropylene (for example, polyethylene and Examples include polypropylene such as block copolymers of ethylene), random copolymers of polypropylene (eg, random copolymers of propylene and ethylene); propylene-α-olefin copolymers; terpolymers of ethylene-butene-propylene, and the like. Among these, polypropylene is preferred. The polyolefin resin in the case of a copolymer may be a block copolymer or a random copolymer. These polyolefin resins may be used alone or in combination of two or more.

Moreover, a cyclic polyolefin may be sufficient as a polyolefin. A cyclic polyolefin is a copolymer of an olefin and a cyclic monomer, and examples of the olefin that is a constituent monomer of the cyclic polyolefin include ethylene, propylene, 4-methyl-1-pentene, styrene, butadiene, and isoprene. It will be done. Examples of the cyclic monomer that is a constituent monomer of the cyclic polyolefin include cyclic alkenes such as norbornene; cyclic dienes such as cyclopentadiene, dicyclopentadiene, cyclohexadiene, and norbornadiene. Among these, cyclic alkenes are preferred, and norbornene is more preferred.

Further, the polyolefin may be an acid-modified polyolefin. Acid-modified polyolefin is a polymer modified by block polymerization or graft polymerization of polyolefin with an acid component. As the acid-modified polyolefin, the aforementioned polyolefins, copolymers obtained by copolymerizing the aforementioned polyolefins with polar molecules such as acrylic acid or methacrylic acid, or polymers such as crosslinked polyolefins can also be used. Further, examples of the acid component used for acid modification include carboxylic acids such as maleic acid, acrylic acid, itaconic acid, crotonic acid, maleic anhydride, and itaconic anhydride, or their anhydrides.

The acid-modified polyolefin may be an acid-modified cyclic polyolefin. Acid-modified cyclic polyolefin is a polymer obtained by copolymerizing some of the monomers constituting the cyclic polyolefin in place of the acid component, or by block polymerizing or graft polymerizing the acid component to the cyclic polyolefin. be. The cyclic polyolefin to be acid-modified is the same as described above. Further, the acid component used for acid modification is the same as the acid component used for modifying the polyolefin described above.

Preferred acid-modified polyolefins include polyolefins modified with carboxylic acids or their anhydrides, polypropylenes modified with carboxylic acids or their anhydrides, maleic anhydride-modified polyolefins, and maleic anhydride-modified polypropylenes.

The heat-fusible resin layer 4 may be formed from one type of resin alone, or may be formed from a blended polymer that is a combination of two or more types of resin. Furthermore, the heat-fusible resin layer 4 may be formed of only one layer, but may be formed of two or more layers of the same or different resins.

When manufacturing the exterior material 10 for an electricity storage device of the present disclosure by laminating the heat-fusible resin layer 4 with the barrier layer 3, the adhesive layer 5, etc., a pre-formed resin film is used as the heat-fusible resin layer 4. May be used. In addition, the heat-fusible resin forming the heat-fusible resin layer 4 is formed into a film on the surface of the barrier layer 3, the adhesive layer 5, etc. by extrusion molding, coating, etc., and the heat-fusible resin formed by the resin film is It may also be used as a synthetic resin layer 4.

Further, the heat-fusible resin layer 4 may contain a lubricant or the like, if necessary. When the heat-fusible resin layer 4 contains a lubricant, the moldability of the exterior material for a power storage device can be improved. The lubricant is not particularly limited, and any known lubricant can be used. The lubricants may be used alone or in combination of two or more.

The lubricant is not particularly limited, but preferably includes an amide lubricant. Specific examples of the lubricant include those exemplified for the base layer 1. One type of lubricant may be used alone, or two or more types may be used in combination.

When a lubricant is present on the surface of the heat-fusible resin layer 4, its amount is not particularly limited, but from the viewpoint of improving the moldability of the exterior material for power storage devices, it is preferably about 10 to 50 mg/m ² More preferably, it is about 15 to 40 mg/m ² .

The lubricant present on the surface of the heat-fusible resin layer 4 may be one obtained by exuding a lubricant contained in the resin constituting the heat-fusible resin layer 4, or The surface may be coated with a lubricant.

Further, the thickness of the heat-fusible resin layer 4 is not particularly limited as long as the heat-fusible resin layers exhibit the function of thermally fusing each other and sealing the electricity storage device element, but is preferably about 100 μm or less, for example. The thickness is about 85 μm or less, more preferably about 15 to 85 μm. Note that, for example, when the thickness of the adhesive layer 5 described below is 10 μm or more, the thickness of the heat-fusible resin layer 4 is preferably about 85 μm or less, more preferably about 15 to 45 μm, for example. When the thickness of the adhesive layer 5 described below is less than 10 μm or when the adhesive layer 5 is not provided, the thickness of the heat-fusible resin layer 4 is preferably about 20 μm or more, more preferably 35 to 85 μm. The degree is mentioned.

[Adhesive layer 5]
In the exterior material for a power storage device of the present disclosure, the adhesive layer 5 is provided between the barrier layer 3 (or corrosion-resistant film) and the heat-fusible resin layer 4 as necessary in order to firmly adhere them. This is the layer where

The adhesive layer 5 is formed of a resin that can bond the barrier layer 3 and the heat-fusible resin layer 4 together. As the resin used for forming the adhesive layer 5, for example, the same adhesive as the adhesive exemplified for the adhesive layer 2 can be used. In addition, from the viewpoint of firmly adhering the adhesive layer 5 and the heat-fusible resin layer 4, it is preferable that the resin used for forming the adhesive layer 5 contains a polyolefin skeleton. Examples include the polyolefin and acid-modified polyolefin exemplified in the resin layer 4. On the other hand, from the viewpoint of firmly adhering the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 preferably contains acid-modified polyolefin. Examples of acid-modified components include dicarboxylic acids such as maleic acid, itaconic acid, succinic acid, and adipic acid, their anhydrides, acrylic acid, and methacrylic acid. Maleic acid is most preferred. In addition, from the viewpoint of heat resistance of the exterior material for a power storage device, the olefin component is preferably a polypropylene resin, and the adhesive layer 5 most preferably contains maleic anhydride-modified polypropylene.

When the resin used to form the adhesive layer 5 contains a polyolefin skeleton, the adhesive layer 5 preferably contains a resin containing a polyolefin skeleton as a main component, and preferably contains an acid-modified polyolefin as a main component. More preferably, it contains acid-modified polypropylene as a main component. Here, the main component means that the content of the resin components contained in the adhesive layer 5 is, for example, 50% by mass or more, preferably 60% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass. The above means that the resin component is more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, still more preferably 99% by mass or more. For example, the adhesive layer 5 containing acid-modified polypropylene as a main component means that the content of acid-modified polypropylene in the resin components contained in the adhesive layer 5 is, for example, 50% by mass or more, preferably 60% by mass or more, or more. Preferably 70% by mass or more, more preferably 80% by mass or more, still more preferably 90% by mass or more, still more preferably 95% by mass or more, still more preferably 98% by mass or more, even more preferably 99% by mass or more. means.

The fact that the resin constituting the adhesive layer 5 contains a polyolefin skeleton can be analyzed by, for example, infrared spectroscopy, gas chromatography mass spectrometry, etc., and the analytical method is not particularly limited. Furthermore, the fact that the resin constituting the adhesive layer 5 contains an acid-modified polyolefin means that, for example, when a maleic anhydride-modified polyolefin is measured by infrared spectroscopy, there is no anhydride at a wave number of around 1760 cm ^-1 and around a wave number of 1780 cm ^-1 . A peak derived from maleic acid is detected. However, if the degree of acid modification is low, the peak may become small and may not be detected. In that case, it can be analyzed by nuclear magnetic resonance spectroscopy.

Furthermore, from the viewpoint of ensuring durability such as heat resistance and content resistance of the exterior material for power storage devices, and ensuring moldability while reducing thickness, the adhesive layer 5 is made of a resin composition containing acid-modified polyolefin and a curing agent. A cured product is more preferable. Preferred examples of the acid-modified polyolefin include those mentioned above.

Further, the adhesive layer 5 is a cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and a compound having an epoxy group. A cured product of a resin composition containing an acid-modified polyolefin and at least one selected from the group consisting of an isocyanate group-containing compound and an epoxy group-containing compound is particularly preferable. Further, the adhesive layer 5 preferably contains at least one selected from the group consisting of polyurethane, polyester, and epoxy resin, and more preferably contains polyurethane and epoxy resin. Preferred examples of the polyester include ester resins produced by the reaction of epoxy groups and maleic anhydride groups, and amide ester resins produced by the reaction of oxazoline groups and maleic anhydride groups. Note that if unreacted substances of a curing agent such as a compound having an isocyanate group, a compound having an oxazoline group, or an epoxy resin remain in the adhesive layer 5, the presence of the unreacted substances can be detected by, for example, infrared spectroscopy, Confirmation can be performed by a method selected from Raman spectroscopy, time-of-flight secondary ion mass spectrometry (TOF-SIMS), and the like.

Further, from the viewpoint of further increasing the adhesion between the barrier layer 3 and the adhesive layer 5, the adhesive layer 5 is made of at least one selected from the group consisting of oxygen atoms, heterocycles, C=N bonds, and C-O-C bonds. It is preferable that it is a cured product of a resin composition containing one type of curing agent. Examples of the curing agent having a heterocycle include a curing agent having an oxazoline group, a curing agent having an epoxy group, and the like. Further, examples of the curing agent having a C=N bond include a curing agent having an oxazoline group, a curing agent having an isocyanate group, and the like. Further, examples of the curing agent having a C--O--C bond include a curing agent having an oxazoline group, a curing agent having an epoxy group, and the like. The fact that the adhesive layer 5 is a cured product of a resin composition containing these curing agents can be achieved by, for example, gas chromatography mass spectrometry (GCMS), infrared spectroscopy (IR), time-of-flight secondary ion mass spectrometry (TOF). -SIMS), X-ray photoelectron spectroscopy (XPS), and other methods.

The compound having an isocyanate group is not particularly limited, but from the viewpoint of effectively increasing the adhesion between the barrier layer 3 and the adhesive layer 5, polyfunctional isocyanate compounds are preferably used. The polyfunctional isocyanate compound is not particularly limited as long as it is a compound having two or more isocyanate groups. Specific examples of polyfunctional isocyanate curing agents include pentane diisocyanate (PDI), isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), tolylene diisocyanate (TDI), diphenylmethane diisocyanate (MDI), and these can be polymerized or nurated. Examples include polymers, mixtures thereof, and copolymers with other polymers. Further examples include adducts, biurets, isocyanurates, and the like.

The content of the compound having an isocyanate group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. It is more preferable to fall within this range. Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

The compound having an oxazoline group is not particularly limited as long as it is a compound having an oxazoline skeleton. Specific examples of compounds having an oxazoline group include those having a polystyrene main chain, and those having an acrylic main chain. Furthermore, commercially available products include, for example, the Epocross series manufactured by Nippon Shokubai Co., Ltd.

The proportion of the compound having an oxazoline group in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and preferably in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. It is more preferable that the Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

Examples of compounds having epoxy groups include epoxy resins. The epoxy resin is not particularly limited as long as it is a resin that can form a crosslinked structure by the epoxy groups present in the molecule, and any known epoxy resin can be used. The weight average molecular weight of the epoxy resin is preferably about 50 to 2,000, more preferably about 100 to 1,000, and still more preferably about 200 to 800. In the first disclosure, the weight average molecular weight of the epoxy resin is a value measured by gel permeation chromatography (GPC) under conditions using polystyrene as a standard sample.

Specific examples of epoxy resins include trimethylolpropane glycidyl ether derivatives, bisphenol A diglycidyl ether, modified bisphenol A diglycidyl ether, bisphenol F type glycidyl ether, novolac glycidyl ether, glycerin polyglycidyl ether, polyglycerin polyglycidyl ether, etc. can be mentioned. One type of epoxy resin may be used alone, or two or more types may be used in combination.

The proportion of the epoxy resin in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and preferably in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. is more preferable. Thereby, the adhesion between the barrier layer 3 and the adhesive layer 5 can be effectively improved.

The polyurethane is not particularly limited, and any known polyurethane can be used. The adhesive layer 5 may be, for example, a cured product of two-part curable polyurethane.

The proportion of polyurethane in the adhesive layer 5 is preferably in the range of 0.1 to 50% by mass, and preferably in the range of 0.5 to 40% by mass in the resin composition constituting the adhesive layer 5. More preferred. Thereby, it is possible to effectively improve the adhesion between the barrier layer 3 and the adhesive layer 5 in an atmosphere where a component that induces corrosion of the barrier layer, such as an electrolytic solution, is present.

In addition, when the adhesive layer 5 is a cured product of a resin composition containing at least one selected from the group consisting of a compound having an isocyanate group, a compound having an oxazoline group, and an epoxy resin, and the acid-modified polyolefin. , the acid-modified polyolefin functions as a main agent, and the compound having an isocyanate group, the compound having an oxazoline group, and the compound having an epoxy group each function as a curing agent.

When manufacturing the exterior material 10 for an electricity storage device of the present disclosure by laminating the adhesive layer 5 with the barrier layer 3, the heat-fusible resin layer 4, etc., a pre-formed resin film may be used as the adhesive layer 5. . Further, the adhesive layer 5 formed of a resin film is formed by forming a heat-fusible resin forming the adhesive layer 5 into a film on the surface of the barrier layer 3, the heat-fusible resin layer 4, etc. by extrusion molding, coating, etc. You can also use it as

The adhesive layer 5 may contain a modifier having a carbodiimide group.

The thickness of the adhesive layer 5 is preferably about 50 μm or less, about 40 μm or less, about 30 μm or less, about 20 μm or less, about 5 μm or less. Further, the thickness of the adhesive layer 5 is preferably about 0.1 μm or more and about 0.5 μm or more. Further, the thickness range of the adhesive layer 5 is preferably about 0.1 to 50 μm, about 0.1 to 40 μm, about 0.1 to 30 μm, about 0.1 to 20 μm, and about 0.1 to 5 μm. , about 0.5 to 50 μm, about 0.5 to 40 μm, about 0.5 to 30 μm, about 0.5 to 20 μm, and about 0.5 to 5 μm. More specifically, in the case of the adhesive exemplified in adhesive layer 2 or a cured product of acid-modified polyolefin and a curing agent, the thickness is preferably about 1 to 10 μm, more preferably about 1 to 5 μm. Further, when using the resin exemplified for the heat-fusible resin layer 4, the thickness is preferably about 2 to 50 μm, more preferably about 10 to 40 μm. In addition, when the adhesive layer 5 is a cured product of the adhesive exemplified in the adhesive layer 2 or a resin composition containing an acid-modified polyolefin and a curing agent, for example, the resin composition is applied and cured by heating etc. By doing so, the adhesive layer 5 can be formed. Further, when using the resin exemplified for the heat-fusible resin layer 4, the heat-fusible resin layer 4 and the adhesive layer 5 can be formed by extrusion molding, for example. Furthermore, when the heat-fusible resin layer 4 and the adhesive layer 5 are formed by co-extrusion molding, the lower limits of the total thickness of the heat-fusible resin layer 4 and the adhesive layer 5 are 35 μm, 55 μm, and 75 μm. The upper limit is 45 μm, 65 μm, and 85 μm, and the preferred numerical range is 35 to 45 μm, 35 to 65 μm, 35 to 85 μm, 55 to 65 μm, 55 to 85 μm, and 75 to 85 μm.

[Surface coating layer 6]
The exterior material for a power storage device of the present disclosure is provided on the base material layer 1 (base material layer 1 A surface coating layer 6 may be provided on the opposite side of the barrier layer 3). The surface coating layer 6 is a layer located on the outermost layer side of the exterior material for a power storage device when the power storage device is assembled using the exterior material for a power storage device.

Examples of the surface coating layer 6 include resins such as polyvinylidene chloride, polyester, polyamide, epoxy resin, acrylic resin, fluororesin, polyurethane, silicone resin, and phenol resin, and modified products of these resins. Further, it may be a copolymer of these resins or a modified product of the copolymer. Furthermore, a mixture of these resins may be used. The resin is preferably a curable resin. That is, the surface coating layer 6 is preferably composed of a cured product of a resin composition containing a curable resin.

When the resin forming the surface coating layer 6 is a curable resin, the resin may be either a one-liquid curing type or a two-liquid curing type, but preferably a two-liquid curing type. Examples of the two-part curable resin include two-part curable polyurethane, two-part curable polyester, and two-part curable epoxy resin. Among these, two-component curing polyurethane is preferred.

Examples of the two-part curable polyurethane include polyurethanes containing a first part containing a polyol compound and a second part containing an isocyanate compound. Preferred examples include two-component curing polyurethanes in which a polyol such as a polyester polyol, a polyether polyol, or an acrylic polyol is used as a first part and an aromatic or aliphatic polyisocyanate is used as a second part. Examples of the polyurethane include polyurethane containing a polyurethane compound prepared by reacting a polyol compound and an isocyanate compound in advance, and an isocyanate compound. Examples of the polyurethane include a polyurethane compound prepared by reacting a polyol compound and an isocyanate compound in advance, and a polyurethane containing a polyol compound. Examples of the polyurethane include polyurethane obtained by curing a polyurethane compound obtained by reacting a polyol compound and an isocyanate compound in advance with moisture in the air. As the polyol compound, it is preferable to use a polyester polyol having a hydroxyl group in the side chain in addition to the hydroxyl group at the end of the repeating unit. Examples of the second agent include aliphatic, alicyclic, aromatic, and araliphatic isocyanate compounds. Examples of isocyanate compounds include hexamethylene diisocyanate (HDI), xylylene diisocyanate (XDI), isophorone diisocyanate (IPDI), hydrogenated XDI (H6XDI), hydrogenated MDI (H12MDI), tolylene diisocyanate (TDI), and diphenylmethane diisocyanate. (MDI), naphthalene diisocyanate (NDI), and the like. Also included are polyfunctional isocyanate modified products of one or more of these diisocyanates. It is also possible to use multimers (for example trimers) as the polyisocyanate compound. Such multimers include adducts, biurets, nurates, and the like. In addition, an aliphatic isocyanate-based compound refers to an isocyanate that has an aliphatic group and does not have an aromatic ring, and an alicyclic isocyanate-based compound refers to an isocyanate that has an alicyclic hydrocarbon group. refers to an isocyanate having an aromatic ring. Since the surface coating layer 6 is formed of polyurethane, excellent electrolyte resistance is imparted to the exterior material for the electricity storage device.

The surface coating layer 6 may contain the above-mentioned lubricant or anti-oxidant on at least one of the surface and inside of the surface coating layer 6, depending on the functionality to be provided to the surface coating layer 6 and its surface. It may contain additives such as blocking agents, matting agents, flame retardants, antioxidants, tackifiers, and antistatic agents. Examples of the additive include fine particles having an average particle diameter of about 0.5 nm to 5 μm. The average particle diameter of the additive is the median diameter measured by a laser diffraction/scattering particle size distribution measuring device.

The additive may be either inorganic or organic. Further, the shape of the additive is not particularly limited, and examples include spherical, fibrous, plate-like, amorphous, and scaly shapes.

Specific examples of additives include talc, silica, graphite, kaolin, montmorillonite, mica, hydrotalcite, silica gel, zeolite, aluminum hydroxide, magnesium hydroxide, zinc oxide, magnesium oxide, aluminum oxide, 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, acrylate resin, Examples include crosslinked acrylic, crosslinked styrene, crosslinked polyethylene, benzoguanamine, gold, aluminum, copper, and nickel. The additives may be used alone or in combination of two or more. Among these additives, silica, barium sulfate, and titanium oxide are preferred from the viewpoint of dispersion stability and cost. Further, the additive may be subjected to various surface treatments such as insulation treatment and high dispersion treatment.

The method for forming the surface coating layer 6 is not particularly limited, and examples thereof include a method of applying a resin that forms the surface coating layer 6. When adding additives to the surface coating layer 6, a resin mixed with the additives may be applied.

The thickness of the surface coating layer 6 is not particularly limited as long as it exhibits the above-mentioned function as the surface coating layer 6, and may be, for example, about 0.5 to 10 μm, preferably about 1 to 5 μm.

3. Method for producing exterior material for power storage device The method for manufacturing the exterior material for power storage device is not particularly limited as long as a laminate in which each layer of the exterior material for power storage device of the present invention is laminated can be obtained, and in order from the outside, At least a step of obtaining a laminate in which a base material layer, a barrier layer, and a heat-fusible resin layer are laminated, the base material layer including at least one resin layer, and the The resin layer is composed of a resin composition containing polyester A consisting of a diol unit and a dicarboxylic acid unit, wherein the diol unit is an alkylene glycol derived from biomass, and the dicarboxylic acid unit is an alkylene glycol derived from a fossil fuel. It is a dicarboxylic acid derived from

An example of the method for manufacturing the exterior material for a power storage device of the present invention is as follows. First, a laminate (hereinafter sometimes referred to as "laminate A") in which a base material layer 1, an adhesive layer 2, and a barrier layer 3 are laminated in this order is formed. Specifically, the formation of the laminate A is performed by applying the adhesive used for forming the adhesive layer 2 on the base layer 1 or on the barrier layer 3 whose surface has been subjected to a chemical conversion treatment as necessary, using a gravure coating method, It can be carried out by a dry lamination method in which the barrier layer 3 or the base material layer 1 is laminated and the adhesive layer 2 is cured after coating and drying by a coating method such as a roll coating method.

Next, a heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A. When the heat-fusible resin layer 4 is directly laminated on the barrier layer 3, the heat-fusible resin layer 4 is laminated on the barrier layer 3 of the laminate A by a method such as a thermal lamination method or an extrusion lamination method. do it. Further, when the adhesive layer 5 is provided between the barrier layer 3 and the heat-fusible resin layer 4, the adhesive layer 5 and the heat-fusible resin layer 4 can be formed by, for example, (1) extrusion lamination, (2) Lamination can be performed by a thermal lamination method, (3) a sandwich lamination method, (4) a dry lamination method, or the like. (1) As an extrusion lamination method, for example, a method of extruding and laminating the adhesive layer 5 and the heat-fusible resin layer 4 on the barrier layer 3 of the laminate A (co-extrusion lamination method, tandem lamination method) Examples include. (2) Thermal lamination method includes, for example, a method in which a laminate is formed in which the adhesive layer 5 and the heat-fusible resin layer 4 are laminated separately, and this is laminated on the barrier layer 3 of the laminate A; , a method of forming a laminate in which the adhesive layer 5 is laminated on the barrier layer 3 of the laminate A, and laminating this with the heat-fusible resin layer 4, and the like. (3) As a sandwich lamination method, for example, while pouring the molten adhesive layer 5 between the barrier layer 3 of the laminate A and the heat-fusible resin layer 4 formed into a sheet shape in advance, , a method of bonding the laminate A and the heat-fusible resin layer 4 via the adhesive layer 5, and the like. (4) As a dry lamination method, for example, the barrier layer 3 of the laminate A is coated with a solution of an adhesive to form the adhesive layer 5, and then laminated by a method of drying or a method of baking. For example, a method may be used in which a heat-fusible resin layer 4 previously formed in a sheet form is laminated on the adhesive layer 5.

Next, a surface coating layer 6 is laminated on the surface of the base layer 1 opposite to the barrier layer 3, if necessary. The surface coating layer 6 can be formed, for example, by applying the above resin composition for forming the surface coating layer 6 onto the surface of the base layer 1 and curing it. Note that the order of the step of laminating the barrier layer 3 on the surface of the base material layer 1 and the step of laminating the surface coating layer 6 on the surface of the base material layer 1 is not particularly limited. For example, after forming the surface coating layer 6 on the surface of the base material layer 1, the barrier layer 3 may be formed on the surface of the base material layer 1 on the opposite side to the surface coating layer 6.

As described above, in order from the outside: surface coating layer 6 provided as necessary/base layer 1/adhesive layer 2 provided as necessary/barrier layer 3/adhesive layer 5 provided as necessary. / A laminate including the heat-fusible resin layer 4 is formed, but in order to strengthen the adhesiveness of the adhesive layer 2 and the adhesive layer 5 provided as necessary, it may be further subjected to heat treatment. good. Further, as described above, a colored layer may be provided between the base layer 1 and the barrier layer 3.

4. Application of exterior packaging material for power storage devices The exterior packaging material for power storage devices of the present disclosure is used for a package for sealing and accommodating power storage device elements such as a positive electrode, a negative electrode, and an electrolyte. That is, a power storage device element including at least a positive electrode, a negative electrode, and an electrolyte can be housed in a package formed of the exterior material for a power storage device according to the present disclosure to form a power storage device.

Specifically, an electricity storage device element including at least a positive electrode, a negative electrode, and an electrolyte is prepared using the exterior material for an electricity storage device of the present disclosure, with metal terminals connected to each of the positive electrode and the negative electrode protruding outward. , Covering the electricity storage device element so that a flange portion (an area where the heat-fusible resin layers contact each other) is formed around the periphery of the power storage device element, and sealing the heat-fusible resin layers of the flange portion by heat-sealing each other. provides an electricity storage device using an exterior material for an electricity storage device. Note that when a power storage device element is housed in a package formed of the power storage device exterior material of the present disclosure, the heat-fusible resin portion of the power storage device exterior material of the present disclosure is placed on the inside (the surface in contact with the power storage device element). ) to form a package. The heat-fusible resin layers of two exterior materials for power storage devices may be stacked facing each other, and the peripheral edges of the stacked exterior materials for power storage devices may be heat-sealed to form a package; As in the example shown in FIG. 5, a package may be formed by folding and overlapping one exterior material for a power storage device and heat-sealing the peripheral edge portions. When folded and stacked, the package may be formed by heat-sealing the sides other than the folded edges and sealing on three sides, as shown in the example shown in Fig. 5, or the package may be folded back so that a flange can be formed. It may be sealed on all sides. Further, a recessed portion for accommodating the power storage device element may be formed in the exterior material for the power storage device by deep drawing or stretch molding. As in the example shown in FIG. 5, one exterior material for an energy storage device may have a recess and the other exterior material for an energy storage device may not have a recess, or the other exterior material for an energy storage device may also have a recess. may be provided.

The exterior material for power storage devices of the present disclosure can be suitably used for power storage devices such as batteries (including capacitors, capacitors, etc.). Further, the exterior material for a power storage device of the present disclosure may be used for either a primary battery or a secondary battery, but is preferably used for a secondary battery. The types of secondary batteries to which the exterior material for power storage devices of the present disclosure is applied are not particularly limited, and examples include lithium-ion batteries, lithium-ion polymer batteries, all-solid-state batteries, lead-acid batteries, nickel-metal hydride batteries, and nickel-metal hydride batteries. Examples include cadmium storage batteries, nickel/iron storage batteries, nickel/zinc storage batteries, silver oxide/zinc storage batteries, metal air batteries, polyvalent cation batteries, capacitors, and capacitors. Among these secondary batteries, lithium ion batteries and lithium ion polymer batteries are suitable for application of the exterior material for power storage devices of the present disclosure.

The present disclosure will be explained in detail by showing Examples and Comparative Examples below. However, the present disclosure is not limited to the examples.

<Synthesis of PET containing raw materials derived from biomass>
83 parts by mass of terephthalic acid and 62 parts by mass of biomass ethylene glycol (manufactured by India Glycol Ltd.) were supplied as a slurry to a reaction tank, and an esterification reaction was carried out at 240° C. for 5 hours by a conventional direct gravity method. Thereafter, 0.013 parts by mass of trimethyl phosphate (manufactured by Aldrich) was added (15 mmol % based on the acid component), and then the polymerization reaction was carried out under high-temperature vacuum conditions. First, the vacuum degree was raised to 4000 Pa and the polymerization temperature to 280° C. for 40 minutes, and then the vacuum degree was lowered to 200 Pa while maintaining the polymerization temperature of 280° C. to conduct a melt polymerization reaction. The reaction time was 3 hours. The synthesized polymer was discharged into running water in the form of a strand and pelletized using a pelletizer. The pellets were dried at 160° C. for 5 hours and then subjected to solid phase polymerization at 205° C. under a vacuum of 50 Pa in a nitrogen atmosphere to obtain a polymer with an intrinsic viscosity of 0.8 dl/g. Note that the intrinsic viscosity was calculated from the melt viscosity measured at 35° C. using a phenol/tetrachloroethane (component ratio: 3/2) solvent. Differential thermal analysis of the obtained polymer (equipment: Shimadzu DSC-60, measurement conditions: heating at 6°C/min in helium gas) showed a glass transition temperature of 69°C, indicating that the polymer was derived from fossil fuels. It was equivalent to known polyethylene terephthalate obtained from raw materials. Further, when the obtained biomass-derived polyethylene terephthalate was subjected to radiocarbon measurement, the content of biomass-derived carbon was 16% as determined by radiocarbon (C14) measurement.

<Production of PET film 1>
90 parts by mass of PET pellets containing a biomass-derived raw material obtained as described above and 10 parts by mass of a fossil fuel-derived polyethylene terephthalate masterbatch containing 200 ppm of porous silica with an average particle size of 0.9 μm as a lubricant. After drying, it was supplied to an extruder, melted at 285°C, extruded into a sheet from a T-die, and cooled and solidified using a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was stretched in the longitudinal direction at a ratio of 3.5 times, and further stretched in the transverse direction at a ratio of 3.5 times to obtain a biaxially stretched PET film 1 having a thickness of 12.02 μm. Ta.

<Production of PET film 2>
60 parts by mass of PET pellets containing biomass-derived raw materials obtained as described above, 30 parts by mass of recycled PET (repelleted from parts lost during the manufacturing process such as ear loss during film production), and the above-mentioned. After drying 10 parts by mass of the polyethylene terephthalate masterbatch used in the above, it was supplied to an extruder, melted at 285°C, extruded into a sheet from a T-die, and cooled and solidified using a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was stretched in the longitudinal direction at a ratio of 3.5 times, and further stretched in the transverse direction at a ratio of 3.5 times to obtain a biaxially stretched PET film 2 having a thickness of 12 μm.

<Production of PET film 3>
90 parts by mass of polyethylene terephthalate (intrinsic viscosity 0.85 dl/g) manufactured from conventional fossil fuel-derived raw materials and 10 parts by mass of the polyethylene terephthalate masterbatch used above are dried and then supplied to an extruder, It was melted at 285° C., extruded into a sheet through a T-die, and cooled and solidified using a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was stretched in the longitudinal direction at a ratio of 3.5 times, and further stretched in the transverse direction at a ratio of 3.5 times in a tenter to form a biaxially stretched PET film 3 having a thickness of 12 μm. Obtained.

<Production of PET film 4>
90 parts by mass of polyethylene terephthalate (intrinsic viscosity 0.75 dl/g) manufactured from conventional fossil fuel-derived raw materials and 10 parts by mass of the polyethylene terephthalate masterbatch used above are dried and then supplied to an extruder, It was melted at 285° C., extruded into a sheet through a T-die, and cooled and solidified using a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was stretched in the longitudinal direction at a ratio of 3.5 times, and further stretched in the transverse direction at a ratio of 3.5 times to obtain a biaxially stretched PET film 4 having a thickness of 12 μm.

<Production of PET film 5>
60 parts by mass of PET pellets containing biomass-derived raw materials obtained as described above, 30 parts by mass of recycled PET (repelleted from parts lost during the manufacturing process such as ear loss during film production), and the above-mentioned. After drying 10 parts by mass of the polyethylene terephthalate masterbatch used in the above, it was supplied to an extruder, melted at 285°C, extruded into a sheet from a T-die, and cooled and solidified using a cooling roll to obtain an unstretched sheet. Next, this unstretched sheet was stretched in the longitudinal direction at a ratio of 3.8 times, and further stretched in the transverse direction at a ratio of 3.6 times to obtain a biaxially stretched PET film 5 having a thickness of 12 μm.

[Characteristics of biaxially stretched PET films 1 to 5]
For the above-mentioned biaxially stretched PET films 1 to 5, the biomass-derived carbon content, tensile properties (tensile strength at break A, tensile elongation at break, stress B at 5% elongation) and heat shrinkage rate were measured by the following methods. did.

<Carbon content derived from biomass>
The content of biomass-derived carbon was measured for biaxially stretched PET films 1 to 5 by radiocarbon (C14) measurement. The results are shown in Table 1. As mentioned above, it is known that the C14 content in plants that grow by taking in carbon dioxide from the atmosphere, such as corn, is about 105.5 pMC. It is also known that fossil fuels contain almost no C14. Therefore, by measuring the proportion of C14 contained in all carbon atoms in polyester, the proportion of carbon derived from biomass can be calculated. In the present invention, the biomass-derived carbon content Pbio, where the C14 content in polyester is PC14, is defined as follows.
Pbio (%) = PC14/105.5×100

<Tensile properties>
For biaxially stretched PET films 1 to 5, test pieces were cut out from MD and TD to a width of 15 mm and a length of 150 mm. The strength and elongation of the test piece was measured using a tensile tester (Automatic film strength and elongation measuring device "Tensilon AMF/RTA-100" manufactured by Orientec Co., Ltd.). In addition, the F5 value (tensile strength when the film is stretched by 5%) in MD and TD was measured. The tensile strength at break (MPa), tensile elongation at break (%), and stress at 5% elongation (kMPa) of MD and TD were as shown in Table 1.

<Heat shrinkage rate>
For biaxially stretched PET films 1 to 5, test pieces (width 15 mm and length 150 mm) were cut out from MD and TD, respectively; the length direction of the MD test piece is MD, and the length direction of the TD test piece is is TD) was placed in a heating oven at 150°C and heat-treated at 150°C for 30 minutes in accordance with JIS C-2318:2020, and the heat shrinkage rate was measured. The results are shown in Table 1.

Example 1-3 and Comparative Examples 1 and 2
<Manufacture of exterior materials for power storage devices>
As the base material layer, the aforementioned biaxially stretched PET films 1 to 5 (each having a thickness of 12 μm) were used. As shown in Table 1, in Example 1, biaxially oriented PET film 1, in Example 2, biaxially oriented PET film 2, in Example 3, biaxially oriented PET film 5, and in Comparative Example 1, biaxially oriented PET film 3. In Comparative Example 2, biaxially stretched PET film 4 was used. In addition, aluminum foil (JIS H4160:1994 A8021H-O (thickness: 40 μm) was prepared as a barrier layer. A two-component urethane adhesive (polyol compound and aromatic isocyanate compound) was used to harden the adhesive layer. A laminate of base material layer/adhesive layer/barrier layer was produced by laminating the aluminum foil and the base material layer by a dry lamination method so that the final thickness was 3 μm, and then performing an aging treatment. Both sides of the aluminum foil are subjected to a chemical conversion treatment.The chemical conversion treatment of the aluminum foil involves applying a treatment solution consisting of a phenol resin, a chromium fluoride compound, and phosphoric acid to a coating amount of chromium of 10 mg/m ² (dry mass). ) was applied to both sides of aluminum foil using a roll coating method and baked.

Next, an adhesive layer (thickness: 40 μm) and a heat-fusible resin layer (thickness: 40 μm) were laminated on the barrier layer of each laminate obtained above. Specifically, by melt-coextruding maleic anhydride-modified polypropylene as an adhesive layer and random polypropylene as a heat-fusible resin layer, an adhesive layer/heat-fusible resin layer is formed on the barrier layer. The resin layers were laminated to obtain an exterior material for a power storage device in which the base material layer/adhesive layer/barrier layer/adhesive layer/thermal adhesive resin layer were laminated in this order.

<Evaluation of moldability>
The exterior material for a power storage device was cut into a rectangle with a length (MD (Machine Direction) direction) of 90 mm x width (TD (Transverse Direction) direction) of 150 mm to prepare a test sample. This sample was placed in a rectangular mold (female mold) with a diameter of 31.6 mm (MD direction) x 54.5 mm (TD direction). The maximum height roughness (nominal value of Rz) specified in Table 2 of the comparative surface roughness standard piece is 3.2 μm. Corner R 2.0 mm, ridge R 1.0 mm) and molding metal corresponding to this. Mold (male type, the surface is JIS B 0659-1:2002 Annex 1 (reference), the maximum height roughness (nominal value of Rz) is 1.6 μm as specified in Table 2 of the comparative surface roughness standard piece. Using a corner R of 2.0 mm and an edge R of 1.0 mm), the molding depth was changed in 0.5 mm increments from a molding depth of 0.5 mm at a pressing pressure (surface pressure) of 0.25 MPa, and 10 pieces were each formed. Cold forming (one-stage draw forming) was performed on the sample. At this time, the test sample was placed on the female mold and molded so that the heat-fusible resin layer side was located on the male mold side. Moreover, the clearance between the male mold and the female mold was set to 0.3 mm. The molding was performed in a 25°C environment. The sample after cold forming was illuminated with a penlight in a dark room to check whether pinholes or cracks were generated in the aluminum alloy foil due to the transmission of light. Amm is the deepest molding depth at which pinholes or cracks do not occur in the aluminum alloy foil in all 10 samples, and the number of samples where pinholes, etc. occur at the shallowest molding depth at which pinholes, etc. occur in the aluminum alloy foil. was set as B, and the value calculated by the following formula was rounded to the second decimal place, and the value was determined as the limit molding depth of the exterior material for an electricity storage device. The moldability was evaluated based on the limit molding depth using the following moldability evaluation criteria. The results are shown in Table 1.
Limit forming depth = Amm + (0.5mm/10 pieces) x (10 pieces - B pieces)

(Moldability evaluation criteria)
A: 6.5 mm or more B: Limit forming depth is 6.0 mm or more and less than 6.5 mm C: Limit forming depth is less than 6.0 mm

As described above, the present disclosure provides inventions of the following aspects.
Item 1. Consisting of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-fusible resin layer,
The base material layer includes at least one resin layer,
The resin layer is composed of a resin composition containing polyester A consisting of diol units and dicarboxylic acid units,
The polyester A is an exterior material for a power storage device, wherein the diol unit is an alkylene glycol derived from biomass, and the dicarboxylic acid unit is a dicarboxylic acid derived from fossil fuel.
Item 2. Item 2. The exterior material for a power storage device according to Item 1, wherein the content of the polyester A in the resin composition is 50% by mass or more.
Item 3. The resin composition further includes a polyester B consisting of a diol unit and a dicarboxylic acid unit,
The polyester B is a polyester obtained by recycling a resin product made of a polyester in which the diol unit is a fossil fuel-derived diol or a biomass-derived alkylene glycol, and the dicarboxylic acid unit is a fossil fuel-derived dicarboxylic acid. Item 2. Exterior material for an electricity storage device according to item 1 or 2.
Item 4. Item 4. The exterior material for an electricity storage device according to Item 3, wherein the content of the polyester B in the resin composition is 50% by mass or less.
Item 5. Item 5. The exterior packaging material for a power storage device according to any one of Items 1 to 4, wherein the fossil fuel-derived dicarboxylic acid is terephthalic acid.
Item 6. Item 6. The exterior material for a power storage device according to any one of Items 1 to 5, wherein the resin composition further contains an additive.
Section 7. Item 7. The exterior material for a power storage device according to any one of Items 1 to 6, wherein the content of the additive in the resin composition is 5% by mass or more.
Section 8. The additives include plasticizers, ultraviolet stabilizers, color inhibitors, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, yarn friction reducers, mold release agents, antioxidants, and ion exchange agents. Item 8. The exterior packaging material for an electricity storage device according to item 6 or 7, which is at least one member selected from the group consisting of a coloring agent and a coloring pigment.
Item 9. Item 8. The electricity storage according to any one of Items 1 to 8, wherein the content of biomass-derived carbon based on radiocarbon (C14) measurement is 10 to 19% based on the total carbon in the resin composition. Exterior material for devices.
Item 10. Item 10. The exterior material for a power storage device according to any one of Items 1 to 9, wherein the resin layer is a biaxially stretched film.
Item 11. Item 11. The exterior packaging material for a power storage device according to any one of Items 1 to 10, wherein the barrier layer is made of aluminum alloy foil or stainless steel foil.
Item 12. Item 12. The exterior packaging material for a power storage device according to any one of Items 1 to 11, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer.
Item 13. A step of obtaining a laminate in which at least a base material layer, a barrier layer, and a heat-fusible resin layer are laminated in order from the outside,
The base material layer includes at least one resin layer,
The resin layer is composed of a resin composition containing polyester A consisting of diol units and dicarboxylic acid units,
In the polyester A, the diol unit is a biomass-derived alkylene glycol, and the dicarboxylic acid unit is a fossil fuel-derived dicarboxylic acid.
Section 14. An electricity storage device, wherein an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the exterior material for an electricity storage device according to any one of Items 1 to 12.

1 Base material layer 2 Adhesive layer 3 Barrier layer 4 Heat-fusible resin layer 5 Adhesive layer 6 Surface coating layer 10 Exterior material for power storage device

Claims (14)

Consisting of a laminate including, in order from the outside, at least a base material layer, a barrier layer, and a heat-fusible resin layer,
The base material layer includes at least one resin layer,
The resin layer is composed of a resin composition containing polyester A consisting of diol units and dicarboxylic acid units,
The polyester A is an exterior material for a power storage device, wherein the diol unit is an alkylene glycol derived from biomass, and the dicarboxylic acid unit is a dicarboxylic acid derived from fossil fuel. The exterior material for a power storage device according to claim 1, wherein the content of the polyester A in the resin composition is 50% by mass or more. The resin composition further includes a polyester B consisting of a diol unit and a dicarboxylic acid unit,
The polyester B is a polyester obtained by recycling a resin product made of a polyester in which the diol unit is a fossil fuel-derived diol or a biomass-derived alkylene glycol, and the dicarboxylic acid unit is a fossil fuel-derived dicarboxylic acid. The exterior material for an electricity storage device according to claim 1 or 2. The exterior material for a power storage device according to claim 3, wherein the content of the polyester B in the resin composition is 50% by mass or less. The exterior material for an electricity storage device according to claim 1 or 2, wherein the fossil fuel-derived dicarboxylic acid is terephthalic acid. The exterior material for a power storage device according to claim 1 or 2, wherein the resin composition further contains an additive. The exterior material for a power storage device according to claim 1 or 2, wherein the content of the additive in the resin composition is 5% by mass or more. The additives include plasticizers, ultraviolet stabilizers, color inhibitors, matting agents, deodorants, flame retardants, weathering agents, antistatic agents, yarn friction reducers, mold release agents, antioxidants, and ion exchange agents. The exterior material for an electricity storage device according to claim 6, which is at least one selected from the group consisting of a coloring agent and a coloring pigment. The exterior material for an electricity storage device according to claim 1 or 2, wherein the content of biomass-derived carbon as measured by radiocarbon (C14) is 10 to 19% based on the total carbon in the resin composition. The exterior material for a power storage device according to claim 1 or 2, wherein the resin layer is a biaxially stretched film. The exterior material for a power storage device according to claim 1 or 2, wherein the barrier layer is made of aluminum alloy foil or stainless steel foil. The exterior material for an electricity storage device according to claim 1 or 2, further comprising an adhesive layer between the barrier layer and the heat-fusible resin layer. A step of obtaining a laminate in which at least a base material layer, a barrier layer, and a heat-fusible resin layer are laminated in order from the outside,
The base material layer includes at least one resin layer,
The resin layer is composed of a resin composition containing polyester A consisting of diol units and dicarboxylic acid units,
In the polyester A, the diol unit is a biomass-derived alkylene glycol, and the dicarboxylic acid unit is a fossil fuel-derived dicarboxylic acid. An electricity storage device, wherein an electricity storage device element comprising at least a positive electrode, a negative electrode, and an electrolyte is housed in a package formed of the exterior material for an electricity storage device according to claim 1 or 2.