Adhesive for power storage device packing material, packing material for power storage device, container for power storage device and power storage device

Abstract

To provide an adhesive for a power storage device packing material which presents high shock resistance after molding processing and a humidity and heat resistance test which is severe in relative to the prior art even with a less application amount, a packing material for a power storage device improved in shock resistance, a container for a power storage device and a power storage device.SOLUTION: An adhesive for a power storage device packaging material is composed of at least a polyester polyol (A) and a polyisocyanate (B), wherein the polyester polyol (A) contains 10 to 60 mol% of constitutional units derived from a polyhydric alcohol (a1) having a melting point of 10 to 50°C, and a storage elastic modulus (Er25 [MPa]) of a cured product at 25°C and a storage elastic modulus (Er60 [MPa]) at 60°C satisfy the following (i) and (ii): (i) Er60 is 50 MPa or more and 1000 MPa or less; and (ii) Er25 and Er60 satisfy 1≤(Er25-Er60) / Er60≤7.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an adhesive for packaging of electricity storage devices, for forming packaging for electricity storage devices such as lithium ion batteries, and relates to an adhesive for packaging of electricity storage devices that exhibits excellent impact resistance when used as a packaging material, a packaging material for electricity storage devices that is excellent in impact resistance and that uses the adhesive, a container for electricity storage devices, and an electricity storage device. [Background technology]

[0002] The rapid growth of electronic devices such as mobile phones and portable personal computers has led to an increasing demand for power storage devices, such as secondary batteries, including lithium-ion batteries and nickel-metal hydride batteries, and electrochemical capacitors, including electric double-layer capacitors. Among these, small lithium-ion batteries have attracted attention due to their high energy density and light weight. While metal cans have traditionally been used as the exterior housings for lithium-ion batteries, packaging materials made of laminated plastic films or metal foils are becoming mainstream from the standpoints of weight reduction and productivity.

[0003] Patent Document 1 discloses an adhesive for battery packaging materials, which is composed of a polyester polyol composition and a polyisocyanate composition, and is characterized in that all of the polybasic acids used as raw materials have aromatic rings and contain a polyester polyol having a predetermined number average molecular weight.

[0004] Patent Document 2 describes an adhesive for packaging materials for electricity storage devices, which is a reaction product of polyester polyol and polyisocyanate and contains a polyurethane resin having hydroxyl groups with a predetermined ester bond concentration, and a polyisocyanate component. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 117080 [Patent Document 2] Japanese Patent Publication No. 2023-6642 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0006] In recent years, as applications such as in-vehicle and home energy storage have expanded, there has been a demand for secondary batteries with larger capacities and improved safety, and packaging materials for energy storage devices are required to have excellent moldability and long-term durability. Furthermore, further weight reduction is required, particularly for in-vehicle applications, and there is a demand for adhesives that maintain their adhesive strength and have high impact resistance even with a small application amount after molding and after more stringent moist heat resistance tests than conventional ones.

[0007] However, the adhesive described in Patent Document 1 has poor flexibility and insufficient shock absorbing ability, resulting in a problem of poor impact resistance.

[0008] The adhesive described in Patent Document 2 does not have a structural unit derived from a polyhydric alcohol with a melting point of 10 to 50°C, and therefore has insufficient cohesive strength, resulting in poor impact resistance.

[0009] The present invention aims to provide an adhesive for packaging materials for electricity storage devices that exhibits high impact resistance even when applied in small amounts after molding and after a more stringent moist heat resistance test than conventional adhesives, as well as packaging materials for electricity storage devices, containers for electricity storage devices, and electricity storage devices that are excellent in impact resistance. [Means for solving the problem]

[0010] As a result of extensive research into solving the above problems, the present inventors have found that the above problems can be solved by the following embodiments, and have thus completed the present invention.

[0011] <1> The present invention provides an adhesive for packaging materials for electrical storage devices, which is composed of at least a polyester polyol (A) and a polyisocyanate (B), wherein the polyester polyol (A) contains 10 to 60 mol % of structural units derived from a polyhydric alcohol (a1) having a melting point of 10 to 50°C, based on the total amount of the polyhydric alcohol components, and the storage modulus at 25°C of a cured product obtained by curing the adhesive (Er 25 [MPa]) and storage modulus at 60°C (Er 60 The adhesive for packaging materials for electricity storage devices satisfies the following (i) and (ii): (i) Er 60 However, the compressive strength is 50 MPa or more and 1000 MPa or less. (ii) Er 25 and Er 60 However, 1≦(Er 25 -Er 60 ) / Er 60 ≦7.

[0012] <2> The present invention relates to a polyester polyol (A) containing 10 to 40 mol % of structural units derived from a polyhydric alcohol (a1) having a melting point of 10 to 50°C, based on the total amount of polyhydric alcohol components. <1> The present invention relates to the adhesive for packaging materials for electricity storage devices described in 1.

[0013] <3> The present invention relates to a polyester polyol (A) having a ratio [NCO] / [OH] of the number of isocyanate groups in the polyisocyanate (B) to the number of hydroxyl groups in the polyester polyol (A) of 5 to 20. <1> or <2> The present invention relates to the adhesive for packaging materials for electricity storage devices described in 1.

[0014] <4> The present invention relates to a polyester polyol (A) having a weight average molecular weight of 50,000 to 100,000. <1> ~ <3> The present invention relates to the adhesive for packaging materials for electricity storage devices according to any one of the above items.

[0015] <5> The present invention provides <1> ~ <4> The present invention relates to a packaging material for an electricity storage device, which comprises an outer adhesive layer made of the adhesive for electricity storage device packaging material according to any one of claims 1 to 4, and has a configuration in which at least an outer resin film layer (1), an outer adhesive layer (2), a metal foil layer (3), an inner adhesive layer (4), and a heat seal layer (5) are laminated in this order from the outside.

[0016] <6> The present invention provides <5> The present invention relates to a container for an electricity storage device formed from the packaging material for an electricity storage device described in 1., wherein the outer layer side resin film layer (1) forms a convex surface and the heat seal layer (5) forms a concave surface.

[0017] <7> The present invention provides <6> The present invention relates to an electricity storage device comprising the electricity storage device container described in 1. [Effects of the Invention]

[0018] According to the present invention, it is possible to provide an adhesive for packaging materials for electricity storage devices that exhibits high impact resistance even when applied in a small amount after molding and after a more stringent moist heat resistance test than conventional ones. Furthermore, by using the adhesive, it is possible to provide packaging materials for electricity storage devices, containers for electricity storage devices, and electricity storage devices that have excellent impact resistance. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view of a packaging material for an electricity storage device of the present invention. [Figure 2] FIG. 1 is a schematic perspective view of one embodiment (tray-shaped) of a container for an electricity storage device of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0020] <Adhesive for packaging materials for energy storage devices> The adhesive for packaging materials for electricity storage devices of the present invention is a urethane-based reactive adhesive composed of at least a polyester polyol (A) and a polyisocyanate (B), in which the polyester polyol (A) contains 10 to 60 mol % of structural units derived from a polyhydric alcohol (a1) having a melting point of 10 to 50°C, based on the total amount of the polyhydric alcohol components, and the storage modulus at 25°C of a cured product obtained by curing the adhesive (Er 25 [MPa]) and storage modulus at 60°C (Er 60 [MPa]) satisfies the following (i) and (ii): (i) Er 60 However, the compressive strength is 50 MPa or more and 1000 MPa or less. (ii) Er 25 and Er 60 However, 1≦(Er 25 -Er 60 ) / Er 60 ≦7. By satisfying the above-mentioned requirements, the adhesive of the present invention can exhibit excellent impact resistance.

[0021] In detail, when packaging materials for power storage devices are produced industrially, they are wound into a roll and then aged for several days in a warehouse maintained at a high temperature in order to fully harden the adhesive layer. 60 When the applied pressure is 50 MPa or more and 1000 MPa or less, the adhesive exhibits wettability to the substrate during aging and cohesive strength, thereby achieving both adhesive strength and impact resistance. 60 If Er is less than 50 MPa, the adhesive layer will have a low cohesive strength during aging, which may result in poor appearance such as displacement or lifting due to cure shrinkage during aging. 60 If the compressive strength exceeds 1000 MPa, the wettability to the substrate decreases during aging, and sufficient adhesive strength is not achieved.

[0022] The adhesive of the present invention also has a storage modulus at 60°C (Er 60 [MPa]) than the storage modulus at 25°C (Er 25 [MPa]) is large, and the equation (ii) (Er25 -Er 60 ) / Er 60 It is important that the relationship between the two values ​​shown in the above specified range is 1 or more and 7 or less. By setting the above specified range, the arrangement and crystallinity of the polyhydric alcohol (a1) having a melting point of 10 to 50°C are controlled in the adhesive layer after aging, and excellent impact resistance is exhibited. To control the crystallinity of the adhesive layer, it is necessary to disrupt the arrangement by aging and then rearrange it by cooling. However, if the value of formula (ii) is less than 1, the degree of crystallinity does not change between 25°C and 60°C, that is, the degree of crystallinity does not change between during aging and upon cooling after aging, so the polyhydric alcohol (a1), which has a melting point of 10 to 50°C, does not arrange, the crystallinity of the adhesive layer is insufficient, and the issue of impact resistance cannot be resolved. If the value of formula (ii) is 7 or more, the adhesive layer exhibits excessive crystallinity, making it hard and brittle, and reducing moldability, moist heat resistance, and impact resistance. The present invention will be described in detail below by taking preferred embodiments as examples.

[0023] [Polyester polyol (A)] The polyester polyol (A) is a compound having two or more hydroxyl groups and two or more ester bonds in the molecule, and contains 10 to 60 mol % of structural units derived from a polyhydric alcohol (a1) having a melting point of 10 to 50° C., based on the total amount of the polyhydric alcohol component. Examples of such polyester polyols include reaction products obtained by reacting a polybasic acid component with a polyhydric alcohol component containing the polyhydric alcohol (a1) in a predetermined amount, and derivatives thereof.

[0024] (Polybasic acid component) Examples of the polybasic acid component include dibasic acids having an aromatic ring (hereinafter referred to as aromatic dibasic acids), such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and phthalic anhydride; aliphatic dibasic acids (hereinafter referred to as aliphatic dibasic acids), such as adipic acid, azelaic acid, sebacic acid, succinic acid, glutaric acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, and itaconic anhydride; dialkyl esters thereof; and mixtures thereof.

[0025] The polybasic acid component preferably contains 5 to 50 mol % of an aliphatic dibasic acid based on the total polybasic acid components. When the amount of aliphatic dibasic acid is 5 mol % or more, the solvent solubility is increased and the viscosity of the resulting polyester polyol solution is reduced. This improves the coatability of the adhesive and results in a packaging material with a more excellent appearance. When the amount is 50 mol % or less, it becomes easier to adjust the glass transition temperature of the polyester polyol, further improving the adhesive strength. From the same viewpoint, the amount of aliphatic dibasic acid is more preferably 25 to 50 mol % based on the total polybasic acid components.

[0026] (Polyhydric alcohol component) It is important that the polyhydric alcohol component contains 10 to 60 mol % of a polyhydric alcohol (a1) having a melting point of 10 to 50°C, based on the total polyhydric alcohol component. The melting point of the polyhydric alcohol (a1) can be measured by differential scanning calorimetry (DSC). Specifically, approximately 2 mg of the compound to be measured is weighed on an aluminum pan, the aluminum pan is placed in a DSC measurement holder, and the temperature is raised at a rate of 5°C / min. The peak temperature of the endothermic peak in the resulting chart is taken as the melting point. When the amount of polyhydric alcohol (a1) having such a predetermined melting point is 10 mol % or more, the crystallinity, i.e., cohesive strength, of the adhesive layer can be enhanced, thereby imparting excellent impact resistance to the packaging material. When the amount is 60 mol % or less, the flexibility, i.e., impact relaxation property, of the adhesive layer can be enhanced, thereby imparting excellent impact resistance to the packaging material. Furthermore, solvent solubility is enhanced, improving stability over time.

[0027] Examples of such polyhydric alcohols (a1) include 1,6-hexanediol (melting point 39°C), butylethylpropanediol (melting point 41°C), 1,4-butanediol (melting point 20°C), and 1,4-cyclohexanedimethanol (melting point 31°C). The melting point of the polyhydric alcohol (a1) is preferably 15°C or higher and 45°C or lower. The proportion of structural units derived from the polyhydric alcohol (a1) is preferably 20 mol% or more, more preferably 30 mol% or more, from the viewpoint of impact resistance, and from the same viewpoint is preferably 45 mol% or less, more preferably 40 mol% or less, and may be, for example, 10 to 40 mol%. Examples of polyhydric alcohol components other than the polyhydric alcohol (a1) include polyols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, butylene glycol, neopentyl glycol, dineopentyl glycol, trimethylolpropane, glycerin, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, 1,9-nonanediol, polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, polyether polyol, polycarbonate polyol, polyolefin polyol, acrylic polyol, and polyurethane polyol; or mixtures thereof.

[0028] The polybasic acid component and the polyhydric alcohol component may each be used alone or in combination of two or more kinds.

[0029] In the reaction between the polybasic acid component and the polyhydric alcohol component, the ratio of the number of hydroxyl groups in the polyhydric alcohol component to the number of carboxyl groups in the polybasic acid component ([OH] / [COOH]) is preferably 1.1 to 1.4, more preferably 1.2 to 1.3. A ratio of 1.1 or more is preferred because the reaction with acid during the dehydration reaction is rapid. A ratio of 1.4 or less is preferred because the transesterification reaction is rapid.

[0030] (Urethane) The polyester polyol (A) may be one in which urethane bonds have been introduced by reacting a portion of the hydroxyl groups with a polyisocyanate (hereinafter, sometimes abbreviated as polyester polyurethane polyol). Examples of the polyester polyol (A) having such urethane bonds include a reaction product of a polyol containing a polyester polyol with a polyisocyanate, and can be obtained by subjecting the hydroxyl groups in the polyol containing the polyester polyol and the isocyanate groups in the polyisocyanate to a urethane reaction under conditions in which the hydroxyl groups are in excess.

[0031] <Polyisocyanate> Examples of the polyisocyanate include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, araliphatic diisocyanates, tri- or higher functional polyisocyanate monomers, and various derivatives derived from the diisocyanates.

[0032] Examples of aliphatic diisocyanates include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methyl caproate.

[0033] Examples of alicyclic diisocyanates include 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,4-bis(isocyanatomethyl)cyclohexane, and 1,3-bis(isocyanatomethyl)cyclohexane.

[0034] Examples of aromatic diisocyanates include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6-tolylene diisocyanate or a mixture thereof, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, and 4,4'-diphenyl ether diisocyanate.

[0035] Examples of the araliphatic diisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω,ω'-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanato-1-methylethyl)benzene or a mixture thereof.

[0036] Examples of tri- or higher functional polyisocyanate monomers include triisocyanates such as triphenylmethane-4,4',4"-triisocyanate, 1,3,5-triisocyanate benzene, and 2,4,6-triisocyanate toluene; and tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate.

[0037] Examples of various derivatives derived from the diisocyanates include adducts of the diisocyanates with low-molecular-weight polyols having a molecular weight of less than 200, such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, and sorbitol, or castor oil; trimers (also called trimers or nurates) of the diisocyanates; biurets; allophanates; and polyisocyanates having a 2,4,6-oxadiazinetrione ring obtained from carbon dioxide and the diisocyanates.

[0038] The polyisocyanate for introducing the urethane bond is preferably an aromatic isocyanate or an alicyclic diisocyanate, and from the viewpoint of moldability or adhesion after a high-temperature, high-humidity test, more preferably tolylene diisocyanate, 4,4'-diphenyl diisocyanate, or 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate.

[0039] The polyol used in combination with the polyester polyol may be a conventionally known polyol, such as the compounds described in the section on polyhydric alcohol components that can be used in the synthesis of the polyester polyol (A), and preferably used are neopentyl glycol and 1,4-butanediol.

[0040] The reaction temperature in the urethanization reaction between a polyol containing a polyester polyol and a polyisocyanate is preferably in the range of 50 to 200° C., more preferably 80 to 150° C. In the urethanization reaction, the ratio of the number of isocyanate groups in the polyisocyanate to the number of hydroxyl groups in the polyol ([NCO] / [OH]) is preferably 0.1 to 0.9, more preferably 0.3 to 0.8.

[0041] The weight-average molecular weight of the polyester polyol (A) before the introduction of urethane bonds is preferably 10,000 or more and 30,000 or less. When the weight-average molecular weight is 10,000 or more, adhesion to the substrate is improved and moldability is excellent. When the weight-average molecular weight is 30,000 or less, the amount of hydroxyl groups at the polyester polyol terminals is not too small, and the reaction time in the above-mentioned urethane reaction can be prevented from being prolonged.

[0042] The weight-average molecular weight of the polyester polyol (A) having a urethane bond is preferably 50,000 or more and 100,000 or less from the viewpoints of coatability, adhesive strength, moldability, moist heat resistance, and impact resistance, more preferably 55,000 or more from the viewpoint of impact resistance, more preferably 85,000 or less from the viewpoint of adhesive strength, and even more preferably 70,000 or less from the viewpoints of moist heat resistance and impact resistance. Specifically, a weight-average molecular weight of 50,000 or more increases the resin's extensibility, further improving processability. A weight-average molecular weight of 100,000 or less ensures that the adhesive's viscosity falls within an appropriate range, improving coatability. A weight-average molecular weight of 50,000 or more and 85,000 or less improves the adhesive's wettability to the substrate, resulting in excellent adhesive strength. A weight-average molecular weight of 50,000 or more and 70,000 or less further enhances the adhesive's wettability to the substrate, improving adhesive strength, and increasing the crosslink density of the adhesive layer, making it tougher and improving its moist heat resistance and impact resistance. A weight-average molecular weight of 55,000 or more and 70,000 or less increases the adhesive layer's cohesive strength, resulting in high impact resistance.

[0043] The hydroxyl value of the polyester polyol (A) having urethane bonds is preferably 0.5 mgKOH / g or more, more preferably 3 mgKOH / g or more. It is also preferably 20 mgKOH / g or less, more preferably 10 mgKOH / g or less. The hydroxyl groups in the polyester polyol (A) are used in a crosslinking reaction with the polyisocyanate (B) described below. As the crosslinking reaction progresses, the adhesive increases in molecular weight and its heat resistance improves. The hydroxyl value can be determined by a method in accordance with JIS K 1557-1.

[0044] The glass transition temperature of the polyester polyol (A) having a urethane bond is preferably -20°C or higher, more preferably -10°C or higher. It is also preferably 40°C or lower, more preferably 20°C or lower. When the glass transition temperature is -20°C or higher, the cohesive strength of the resin is increased, and adhesiveness is further improved. When the glass transition temperature is 40°C or lower, affinity to the substrate during lamination is increased, and adhesive strength after aging is further improved.

[0045] The adhesive of the present invention may contain a polyol other than the polyester polyol (A) within a range that does not impair the effects of the present invention. Examples of such polyols include polycarbonate polyols, polycaprolactone polyols, polyether polyols, polyolefin polyols, acrylic polyols, silicone polyols, castor seed oil-based polyols, and fluorine-based polyols.

[0046] <Polyisocyanate (B)> Polyisocyanate (B) crosslinks with the hydroxyl groups in polyester polyol (A) to increase molecular weight, improving the internal cohesive strength of the adhesive layer and providing energy resilience. Furthermore, isocyanate groups react with water to form highly cohesive urea bonds, which undergo a self-crosslinking reaction during aging, further increasing the cohesive strength of the adhesive layer. Polyisocyanate (B) also enhances interaction with the substrate surface, as described below. In particular, the chemical reaction between the hydroxyl groups on the substrate surface, which has been physically or chemically treated (e.g., corona discharge treatment or acid modification), and the reactive functional groups in polyisocyanate (B) creates a strong interaction between the outer adhesive layer and the substrate. In this way, by using polyisocyanate (B), it is possible to form a strong outer adhesive layer, and the adhesive layer suppresses the expansion and contraction movement of the substrate due to sudden environmental changes, making it possible to maintain a high level of adhesive strength.

[0047] As the polyisocyanate (B), those listed in the section "Polyisocyanate" of (Urethane Formation) in [Polyester Polyol (A)] described above can be used, and one type may be used alone, or two or more types may be used in combination. Among these, preferred polyisocyanates (B) are nurates of diisocyanates, adducts in which trimethylolpropane is added to diisocyanates, biuret types, prepolymers having an isocyanate residue (e.g., low polymers obtained from diisocyanates and polyols), uretdiones having an isocyanate residue, allophanates, or complexes thereof. The polyisocyanate (B) can achieve excellent heat resistance, cohesive strength, and processability in electronic device applications, regardless of the type of isocyanate, such as an aliphatic diisocyanate, an alicyclic diisocyanate, an aromatic diisocyanate, or an araliphatic diisocyanate.

[0048] In the adhesive of the present invention, the ratio [NCO] / [OH] of the number of isocyanate groups in the polyisocyanate (B) to the number of hydroxyl groups in all polyols including the polyester polyol (A) is preferably 5-20, more preferably 10-15. When the [NCO] / [OH] ratio is 5 or more, the number of crosslinking points increases and moisture permeability decreases, improving moist heat resistance. From this perspective, a ratio of 10 or more is more preferable. When the [NCO] / [OH] ratio is 20 or less, it is advantageous in terms of curing time, hygiene, and economy, and the resulting adhesive layer does not become hard or brittle, achieving both excellent adhesive strength and impact resistance. Furthermore, from the viewpoint that the adhesive layer exhibits appropriate flexibility, improving moldability and impact resistance, a ratio of 15 or less is more preferable.

[0049] Furthermore, the polyisocyanate component (B) exhibits good adhesive strength, moldability, moist heat resistance, and impact resistance, regardless of the type of isocyanate, such as an aliphatic diisocyanate, alicyclic diisocyanate, aromatic diisocyanate, or araliphatic diisocyanate, as long as it has an appropriate [NCO] / [OH] ratio. The outer adhesive layer (2) in the present invention is formed from a polyurethane adhesive containing a polyester polyol (A) and a curing agent containing a polyisocyanate component (B).

[0050] <Storage modulus (Er) of cured product at 250°C> The adhesive of the present invention has a storage modulus (Er 25 [MPa]) and storage modulus at 60°C (Er 60 [MPa]) satisfies the following (i) and (ii). (i) Er 60 However, the compressive strength is 50 MPa or more and 1000 MPa or less. (ii) Er 25 and Er 60 However, 1≦(Er 25 -Er 60 ) / Er 60 ≦7. From the viewpoint of achieving both wettability to the substrate during aging and cohesive strength of the adhesive, as well as adhesive strength and impact resistance, Er60 is preferably 100 MPa to 500 MPa. Furthermore, from the viewpoint of exhibiting appropriate crystallinity and improving impact resistance by appropriately arranging the polyhydric alcohol (a1) having a melting point of 10 to 50°C during cooling after aging, the value of the formula (ii) is preferably 3 to 5.

[0051] The storage modulus can be determined by the following method based on JIS K 7244. The adhesive was spread thinly onto a non-corona-treated, unstretched polypropylene (CPP) film using an applicator to achieve a cured film thickness of 10-30 μm. The adhesive was then left to cure at 80°C for two weeks to obtain a laminate. The laminate was then cut into pieces 20 mm long and 5 mm wide, and the CPP film was peeled off to obtain a cured product measuring 20 mm long, 5 mm wide, and 10-30 μm thick. The resulting cured product was measured using a dynamic viscoelasticity analyzer (IT Measurement & Control Co., Ltd., "DVA-200") at a temperature starting from -30°C to 350°C, a frequency of 10 Hz, and a heating rate of 10°C / min, to determine the storage modulus at 25°C and 60°C.

[0052] (solvent) The adhesive of the present invention may contain a solvent to the extent that it does not affect the substrate during the drying process, in order to adjust the coating liquid to an appropriate viscosity when the adhesive is applied to a substrate. Examples of solvents include ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and methoxyethyl acetate; ether-based solvents such as diethyl ether and ethylene glycol dimethyl ether; aromatic solvents such as toluene and xylene; aliphatic solvents such as pentane and hexane; and halogenated hydrocarbon solvents such as methylene chloride, chlorobenzene, and chloroform. These solvents may be used alone or in combination. Among these, ethyl acetate is preferred.

[0053] <Other ingredients> The adhesive of the present invention may further contain other components within the range that does not impair the effects of the present invention. The other components may be blended with any of the above-mentioned components or may be added when blending them, but it is more preferable to blend them with the main component (A).

[0054] (Reaction accelerator) The adhesive may further contain a reaction accelerator to promote the urethanization reaction. Examples of reaction accelerators include metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimaleate; tertiary amines such as 1,8-diaza-bicyclo(5,4,0)undecene-7 and 1,5-diazabicyclo(4,3,0)nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)undecene-7; and reactive tertiary amines such as triethanolamine. One or more reaction accelerators selected from these groups may be used.

[0055] (Silane coupling agent) The adhesive may further contain a silane coupling agent to improve adhesive strength to metal materials such as metal foil. Examples of the silane coupling agent include trialkoxysilanes having a vinyl group, such as vinyltrimethoxysilane and vinyltriethoxysilane; trialkoxysilanes having an amino group, such as 3-aminopropyltriethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane; and trialkoxysilanes having a glycidyl group, such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane. The content of the silane coupling agent is preferably 0.1 to 5 mass %, more preferably 0.5 to 3 mass %, based on the solid mass of the polyester polyol (A). By adding the silane coupling agent in the above range, the adhesive strength to the metal foil can be further improved.

[0056] (epoxy resin) An epoxy resin can be further added to the adhesive to improve the adhesive strength to metal materials such as metal foil. In particular, when an epoxy resin is added to the polyester polyol (A), the acid generated by hydrolysis during moist heat resistance reacts with the epoxy resin, further improving moist heat resistance. Examples of epoxy resins include, but are not limited to, bisphenol A epoxy resins, bisphenol F epoxy resins, phenol novolac epoxy resins, cresol novolac epoxy resins, polyglycerol polyglycidyl ether, 1,6-hexanediol diglycidyl ether, bisphenol A diglycidyl ether, propylene oxide-modified bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether. These epoxy resins may be used alone or in combination of two or more.

[0057] From the viewpoints of adhesive strength and moist heat resistance, the epoxy resin preferably has a weight average molecular weight of 400 to 10,000. From the viewpoints of adhesive strength and moist heat resistance, the amount of epoxy resin blended is preferably 5 to 50 mass %, more preferably 10 to 20 mass %, based on the solid mass of the polyester polyol (A). By making it 5 mass % or more, moist heat resistance is more effectively improved. By making it 50 mass % or less, the adhesive layer becomes appropriately soft and exhibits sufficient adhesiveness.

[0058] (phosphorus acid or its derivatives) The adhesive can contain phosphoric acid or a phosphoric acid derivative to improve adhesive strength to metal materials such as metal foil. The phosphoric acid may be any phosphoric acid having at least one free oxygen acid, such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, or hypophosphoric acid; or condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, or ultraphosphoric acid. Phosphoric acid derivatives include those obtained by partially esterifying the above phosphoric acids with alcohols while leaving at least one free oxygen acid. Examples of these alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol, and glycerin; and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglucinol. The phosphoric acid or its derivative may be used alone or in combination of two or more thereof. The amount of phosphoric acid or its derivative added is preferably 0.01 to 10 mass %, more preferably 0.05 to 5 mass %, and even more preferably 0.05 to 1 mass %, based on the solid content mass of the polyester polyol (A).

[0059] (Leveling agent, antifoaming agent) The adhesive may further contain a leveling agent or an antifoaming agent to improve the laminate appearance of the packaging material. Examples of leveling agents include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl group-containing polydimethylsiloxane, polyetherester-modified hydroxyl group-containing polydimethylsiloxane, acrylic copolymer, methacrylic copolymer, polyether-modified polymethylalkylsiloxane, acrylic acid alkyl ester copolymer, methacrylic acid alkyl ester copolymer, and lecithin. Examples of the antifoaming agent include known antifoaming agents such as silicone resin, silicone solution, copolymers of alkyl vinyl ether, alkyl acrylate ester and alkyl methacrylate ester.

[0060] (additives) The adhesive may contain additives other than those described above, provided that the effects of the present invention are not impaired. Examples of additives include inorganic fillers such as silica, alumina, mica, talc, aluminum flakes, and glass flakes, layered inorganic compounds, stabilizers (antioxidants, heat stabilizers, UV absorbers, hydrolysis inhibitors, etc.), rust inhibitors, thickeners, plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, fillers, nucleating agents, and catalysts for adjusting the curing reaction.

[0061] <Packaging materials for power storage devices> [Outer adhesive layer (2)] The adhesive of the present invention can be used as an adhesive for forming an adhesive layer of a packaging material for a storage battery device, and can be particularly suitably used as an outer layer adhesive for forming an outer layer adhesive layer (2) of a packaging material for a storage battery device. The packaging material for an electricity storage device of the present invention has an outer adhesive layer (2) made of the adhesive described above, and has a configuration in which at least an outer resin film layer (1), an outer adhesive layer (2), a metal foil layer (3), an inner adhesive layer (4), and a heat seal layer (5) are laminated from the outside in this order.

[0062] The method for producing the packaging material for an electricity storage device is not particularly limited, and the material can be produced by a known method. For example, an outer layer side resin film layer (1) and a metal foil layer (3) can be laminated using the above-mentioned adhesive for packaging materials for electricity storage devices to obtain an intermediate laminate having a configuration of outer layer side resin film layer (1) / outer layer side adhesive layer (2) / metal foil layer (3), and then a heat seal layer (5) can be laminated on the surface of the metal foil layer (3) of the intermediate laminate using an inner layer side adhesive (hereinafter referred to as manufacturing method 1). Alternatively, the metal foil layer (3) and the heat seal layer (5) can be laminated together using an inner layer adhesive to obtain an intermediate laminate having a configuration of metal foil layer (3) / inner layer adhesive layer (4) / heat seal layer (5), and then the metal foil layer (3) of the intermediate laminate and the outer layer resin film layer (1) can be laminated together using the above-mentioned adhesive for packaging materials for electricity storage devices (hereinafter referred to as manufacturing method 2).

[0063] In the case of manufacturing method 1, the adhesive for packaging materials for electricity storage devices is applied to one side of the substrate, either the outer layer side resin film layer (1) or the metal foil layer (3), and after the solvent is evaporated, the other substrate is laminated onto the uncured outer layer side adhesive layer under heat and pressure, and then aging is performed at room temperature to less than 100°C to cure the outer layer side adhesive layer. If the aging temperature is less than 100°C, thermal shrinkage of the outer layer side resin film layer (1) does not occur, so there is no decrease in breaking elongation or breaking stress that affects molding, and no decrease in molding productivity due to film curl. The coating amount of the outer layer side adhesive after drying is 1 to 15 g / m 2 It is preferable that the degree of Similarly, in the case of production method 2, the adhesive for packaging materials for electricity storage devices may be applied to either the outer layer side resin film layer (1) or the surface of the metal foil layer (3) of the intermediate laminate.

[0064] Furthermore, even if the adhesive layer of the packaging material for an electricity storage device of the present invention is thin, it exhibits high impact resistance after molding and after a moist heat resistance test that is more severe than conventional tests. Specifically, the packaging material for an electricity storage device of the present invention exhibits high impact resistance when the applied amount of the adhesive after drying is 3 g / m 2 The application amount is reduced to 2g / m 2 Even if the adhesive strength is less than 100%, the adhesive strength is maintained after molding and after a moist heat resistance test that is more stringent than conventional adhesives, and high impact resistance is also exhibited.

[0065] Examples of methods for forming the outer adhesive layer include methods using a comma coater, dry laminator, roll knife coater, die coater, roll coater, bar coater, gravure roll coater, reverse roll coater, blade coater, gravure coater, and microgravure coater.

[0066] [Outer layer resin film layer (1)] The outer resin film layer (1) is not particularly limited, and is preferably a stretched film made of polyamide, polyester, or polyimide, which may be colored with a pigment such as carbon black or titanium oxide. The non-laminated surface of the outer resin film layer (1) may be coated with a coating agent for scratch prevention and electrolyte resistance, a slip agent for providing slipperiness during molding, or a printing ink for decorative purposes. The outer resin film layer (1) may be formed by laminating two or more films in advance. The thickness of the outer resin film layer (1) is not particularly limited, but is preferably 12 to 100 μm.

[0067] [Metal foil layer (3)] The metal foil layer (3) is not particularly limited, but is preferably an aluminum foil layer. The thickness of the metal foil layer (3) is not particularly limited, but is preferably 20 to 80 μm. The surface of the metal foil layer (3) is preferably subjected to a known antiseptic treatment such as chromate phosphate treatment, chromate chromate treatment, trivalent chromium treatment, zinc phosphate treatment, zirconium phosphate treatment, zirconium oxide treatment, titanium phosphate treatment, hydrofluoric acid treatment, cerium treatment, or hydrotalcite treatment. The antiseptic treatment can prevent corrosion and deterioration of the metal foil surface in the electrolyte filled inside the battery. Furthermore, it is preferable to apply a known organic component such as a phenolic resin, an amide resin, an acrylic resin, polyvinyl alcohol, or a coupling agent to the antiseptic-treated surface, or to apply a mixture of the antiseptic component and the organic component, and then bake the metal foil layer at a high temperature of approximately 200°C. This application-type organic primer treatment can more firmly bond the metal foil and adhesive, further suppressing lifting between the metal foil and adhesive.

[0068] [Heat seal layer (5)] The heat seal layer (5) is not particularly limited, but is preferably an unstretched film made of at least one thermoplastic resin selected from the group consisting of polyester, polyethylene, polypropylene, olefin copolymers, acid-modified products thereof, and ionomers. The thickness of the heat seal layer is not particularly limited, but is preferably 20 to 150 μm.

[0069] [Inner layer adhesive layer (4)] The adhesive forming the inner layer adhesive layer (4) is not particularly limited, but it is preferable that the adhesive strength between the metal foil layer (3) and the heat seal layer (5) is not reduced by the electrolyte of the electricity storage device, and any known adhesive can be used. The inner layer side adhesive layer (4) can be formed, for example, by applying an adhesive made of a combination of polyolefin resin and polyisocyanate or an adhesive made of a combination of polyol and polyisocyanate to the metal foil layer (3) using a gravure coater or the like, drying the solvent, laminating the heat seal layer (5) on the adhesive layer under heat and pressure, and then aging the resultant at room temperature or under elevated temperature. Alternatively, an adhesive such as acid-modified polypropylene can be melt-extruded onto the metal foil layer (3) using a T-die extruder to form an adhesive layer, and a heat-seal layer (5) can be placed on the adhesive layer, and the metal foil layer (3) and the heat-seal layer (5) can be bonded together to form the inner layer adhesive layer (4). When both the outer adhesive layer (2) and the inner adhesive layer (4) require aging, they may be aged together after obtaining a laminate having a configuration in which the outer resin film layer (1), the uncured outer adhesive layer, the metal foil layer (3), the uncured inner adhesive layer, and the heat seal layer (5) are laminated in this order from the outside.

[0070] <Container for electricity storage device> The container for an electricity storage device of the present invention can be obtained by molding the packaging material for an electricity storage device of the present invention so that the outer resin film layer (1) forms a convex surface and the heat seal layer (5) forms a concave surface. The "concave surface" in the present invention means a surface having a depression capable of containing an electrolyte solution when the packaging material for an electricity storage device in a flat state is molded into a tray shape as shown in Fig. 2, and the "convex surface" in the present invention means the surface opposite to the surface having the depression.

[0071] <Electricity storage device> The electricity storage device of the present invention uses the container for an electricity storage device, and examples thereof include secondary batteries such as lithium ion batteries, nickel-metal hydride batteries and lead-acid batteries, and electrochemical capacitors such as electric double layer capacitors. A typical electricity storage device comprises a battery element including electrodes, leads extending from the electrodes, and a container that houses them, and in the electricity storage device of the present invention, the container for an electricity storage device is used as the container for housing. The container for housing may be formed from a packaging material for an electricity storage device so that the heat seal layer (5) is on the inside, and may be obtained by overlapping two packaging materials with the heat seal layers (5) facing each other and heat-sealing the peripheral edges of the overlapped packaging materials, or by folding one packaging material over and overlapping it, and similarly heat-sealing the peripheral edges of the packaging materials. [Example]

[0072] The present invention will be described in more detail below with reference to examples and comparative examples. In the examples and comparative examples, "parts" and "%" mean "parts by mass" and "% by mass" unless otherwise specified.

[0073] <Acid value (AV) measurement> Approximately 1 g of sample (polyester polyol solution) was precisely weighed and placed in a stoppered Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2 / 1) mixture was added and dissolved. Phenolphthalein test solution was added as an indicator and the mixture was allowed to stand for 30 seconds. The solution was then titrated with 0.1 N alcoholic potassium hydroxide solution until it turned a pale pink color, and the acid value (mgKOH / g) was calculated using the following formula. Acid value (mgKOH / g)=(5.611×a×F) / S Where S: sample amount (g) a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml) F: Potency of 0.1N alcoholic potassium hydroxide solution

[0074] <Hydroxyl value (OHV) measurement> Approximately 1 g of sample (polyester polyol, hydroxyl group-containing urethane resin (a), etc.) was precisely weighed and placed in a stoppered Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2 / 1) mixture was added and dissolved. Exactly 5 ml of an acetylating agent (a solution prepared by dissolving 25 g of acetic anhydride in pyridine to a volume of 100 ml) was then added and stirred for approximately 1 hour. Phenolphthalein test solution was added as an indicator and the mixture was stirred for 30 seconds. The solution was then titrated with 0.5 N alcoholic potassium hydroxide solution until it turned pale pink, and the hydroxyl value (mg KOH / g) was calculated using the following formula. Hydroxyl value (mgKOH / g) = [{(ba) × F × 28.05} / S] + D Where S: sample amount (g) a: Consumption of 0.5N alcoholic potassium hydroxide solution (ml) b: Amount of 0.5N alcoholic potassium hydroxide solution consumed in the blank experiment (ml) F: Potency of 0.5N alcoholic potassium hydroxide solution D: Acid value (mgKOH / g)

[0075] <Measurement of average molecular weight and molecular weight distribution> The number average molecular weight (Mn), weight average molecular weight (Mw), and molecular weight distribution (Mw / Mn) were measured using Showdex (registered trademark) (manufactured by Showa Denko K.K.) columns: KF-805L, KF-803L, and KF-802 (all trade names, manufactured by Showa Denko K.K.), with a column temperature of 40°C, THF as eluent, a flow rate of 0.2 ml / min, detection by RI, and a sample concentration of 0.02% by mass, and the values ​​were used as standard polystyrene equivalents.

[0076] <Glass transition temperature (Tg)> The glass transition temperature was measured by DSC (differential scanning calorimetry). Specifically, approximately 2 mg of the compound to be measured was weighed on an aluminum pan, the aluminum pan was set in a DSC measurement holder, and the endothermic peak of the chart obtained under the temperature rising condition of 5°C / min was read, and the peak temperature at this time was taken as the glass transition temperature.

[0077] <Synthesis of polyester polyol> (Polyol 1) 196 parts of phthalic anhydride, 157 parts of terephthalic acid, 221 parts of adipic acid, 98 parts of ethylene glycol, 141 parts of neopentyl glycol, and 187 parts of 1,6-hexanediol were charged and subjected to an esterification reaction at 170 to 230°C for 11 hours. After distilling off the required amount of water, 0.05 parts of tetraisobutyl titanate was added, and the pressure was gradually reduced. The transesterification reaction was carried out at 1.3 to 2.6 hPa and 230 to 250°C for 3 hours. Polyol 1, a polyester polyol with a number average molecular weight (Mn) of 9,300, a weight average molecular weight (Mw) of 18,200, a molecular weight distribution (Mw / Mn) of 1.96, a hydroxyl value of 13.1 mg KOH / g, and a glass transition temperature of -13°C, was obtained in an 82.1% yield. Based on the total amount of polyhydric alcohol components, the content of polyhydric alcohol (a1) having a melting point of 10 to 50°C was 35 mol%.

[0078] (Polyols 2 to 11) Polyols 2 to 11 were obtained by carrying out an esterification reaction in the same manner as for Polyol 1, except that the amounts of the polybasic acid component and the polyhydric alcohol component charged were changed to the blending ratios shown in Table 1.

[0079] [Table 1]

[0080] The abbreviations in Table 1 are as follows: PA: Phthalic anhydride IPA: Isophthalic acid TPA: Terephthalic acid AdA: adipic acid SeA: Sebacic acid AzA: Azelaic acid EG: Ethylene glycol (melting point -13°C) NPG: Neopentyl glycol (melting point 129°C) 1,6-HD: 1,6-hexanediol (melting point 39°C) BEPG: Butyl ethyl propanediol (melting point 41°C) MPO: 2-methyl-1,3-propanediol (melting point -91°C) DEG: Diethylene glycol (melting point -12°C)

[0081] <Production of Polyester Polyol Solution Having Urethane Bonds> (Polyol solution 1) 100 parts of the obtained polyol 1 and 43 parts of ethyl acetate were placed in a four-neck flask, heated to 85°C, and stirred until the solution became homogeneous. 2.1 parts of tolylene diisocyanate and 0.01 parts of dibutyltin dilaurate were added, and the reaction was carried out for 4 hours. After the reaction was completed, 59 parts of ethyl acetate were added to obtain polyol solution 1, a solution of polyester polyol having urethane bonds, with a resin Tg of -10°C, a hydroxyl value of 4.2 mgKOH / g, and a non-volatile content of 50%.

[0082] (Polyol solutions 2 to 13) Polyol solutions 2 to 13, which are solutions of polyester polyols having urethane bonds, were obtained by reacting polyester polyols with polyisocyanates in the same manner as in polyol solution 1, except that the blending compositions were changed as shown in Table 2.

[0083] [Table 2]

[0084] The abbreviations in Table 2 are as follows: TDI: Tolylene diisocyanate (Coronate T-80 (trade name), manufactured by Tosoh Corporation, NCO content 48.2%) IPDI: Isophorone diisocyanate (Desmodur I (trade name), manufactured by Covestro, NCO content 37.7%) HDI: hexamethylene diisocyanate (Desmodur (registered trademark) H (trade name), manufactured by Covestro, NCO content 49.9%)

[0085] <Adjustment of adhesive for packaging materials for energy storage devices> [Example 1] 200 parts (100 parts in solids equivalent) of Polyol Solution 1 and 1.0 part of glycidopropyltrimethoxysilane as an additive were charged and stirred for 30 minutes, then diluted with ethyl acetate to obtain a base agent with a solids concentration of 50%. 31 parts (23 parts in solids equivalent) of Coronate L (trade name, manufactured by Tosoh Corporation, solids concentration 75%, NCO content 13.2%) and 0.01 parts of U-810 (trade name, manufactured by Nitto Kasei Co., Ltd., dibutyltin dilaurate) were charged and diluted with ethyl acetate to obtain an adhesive with a solids concentration of 30%.

[0086] [Examples 2 to 19, Comparative Examples 1 to 5] The adhesives of Examples 2 to 19 and Comparative Examples 1 to 5 were prepared in the same manner as in Example 1, except that the blending compositions were changed to those shown in Table 3.

[0087] The ratio of the number of isocyanate groups to the number of hydroxyl groups in the adhesive ([NCO] / [OH]) was determined as follows. [NCO] / [OH] = [561 x (NCO% of hardener) x (amount of hardener (g) per 100g of base agent)] / [(total hydroxyl value and acid value of base agent (mgKOH / g)) x 42 x 100]

[0088] <Evaluation of adhesives for packaging materials for energy storage devices> The adhesive was cured and its viscoelasticity was measured. Packaging materials were also prepared using the adhesive, and their adhesive strength, moldability, moist heat resistance, and impact resistance were evaluated. The results are shown in Table 3.

[0089] [Viscoelasticity of cured film] The adhesive was thinly spread onto untreated CPP film using an applicator to achieve a cured film thickness of 10-30 μm, and then left to cure at 80°C for two weeks to obtain a laminate. The laminate was then cut into pieces 20 mm long and 5 mm wide, and the CPP film was peeled off to obtain cured products measuring 20 mm long, 5 mm wide, and 10-30 μm thick. The cured products were measured using a dynamic viscoelasticity analyzer (IT Measurement & Control Co., Ltd., "DVA-200") at a temperature starting from -30°C to 350°C, a frequency of 10 Hz, and a heating rate of 10°C / min, to determine the storage moduli at 25°C and 60°C.

[0090] [Packaging material production] First, the adhesive obtained in the Examples or Comparative Examples for the outer adhesive layer (2) was applied to one side of a 40 μm thick aluminum foil, and after the solvent was evaporated, a 30 μm thick stretched polyamide film was laminated thereon to obtain an intermediate laminate. The amount of adhesive applied after drying was 2 g / m. 2 Next, using a dry laminator, an adhesive for the inner layer side adhesive layer, which will be described later, was applied to the other side of the aluminum foil of the obtained intermediate laminate, and after the solvent was evaporated, an unstretched polypropylene film having a thickness of 30 μm was laminated to obtain a laminate. The amount of the adhesive applied after drying was 2 g / m 2 Next, aging was carried out for 7 days under conditions of 60°C and 40% RH (relative humidity), and the outer and inner adhesive layers were cured to obtain a battery packaging material having a configuration of outer resin film layer (1) / outer adhesive layer (2) / metal foil layer (3) / inner adhesive layer (4) / heat seal layer (5).

[0091] (Adhesive for inner adhesive layer) AD-502 (trade name, polyester polyol, manufactured by Toyo-Morton Co., Ltd.) was used as the base agent, and CAT-10L (trade name, isocyanate-based curing agent, manufactured by Toyo-Morton Co., Ltd.) was used as the curing agent, with a base agent / curing agent ratio of 100 / 10 (mass ratio), and the solids concentration was adjusted to 30% with ethyl acetate. This was used as the adhesive for the inner adhesive layer.

[0092] [Adhesive strength] The obtained battery packaging materials were each cut into a size of 200 mm × 15 mm, and a T-peel test was performed using a tensile tester to measure the peel strength (N / 15 mm width) between the stretched polyamide film and the aluminum foil. The measurement was performed in an environment of 20 °C, 65% RH, and a loading rate of 300 mm / min, and the average value of five test pieces was evaluated according to the following criteria. S: Average peel strength is 6N or more (very good) A: Average peel strength is 4N or more and less than 6N (good) B: Average peel strength is 2N or more and less than 4N (usable) C: Average peel strength is less than 2N (unusable)

[0093] [Moldability] The obtained battery packaging material was cut into a size of 80 x 80 mm to prepare a blank. The blank was then subjected to a one-stage overhang molding using a height-free straight mold with the stretched polyamide film facing outward. The moldability was evaluated according to the following criteria based on the maximum molding height at which the aluminum foil did not break or the layers did not float. The punch shape of the mold used was a square with sides of 30 mm, a corner R of 2 mm, and a punch shoulder R of 1 mm.The die hole shape of the mold used was a square with sides of 34 mm, a die hole corner R of 2 mm, and a die hole shoulder R of 1 mm.The clearance between the punch and the die hole was 2 mm on each side, and this clearance caused a slope corresponding to the molding height. S: Maximum molding height is 6 mm or more (very good) A: The maximum molding height is 4 mm or more and less than 6 mm (good). B: The maximum molding height is 2 mm or more and less than 4 mm (usable) C: The maximum molding height is less than 2 mm (unusable)

[0094] [Moisture and heat resistance of molded products] The obtained battery packaging material was cut into a size of 80 x 80 mm to prepare a blank. The blank was then subjected to a one-stage molding process with a height-free straight mold, with the stretched polyamide film facing outward, to a molding height of 3 mm, to obtain a molded product. The molded product was then placed in a constant temperature and humidity chamber under an atmosphere of 85°C and 85% RH and allowed to stand for two weeks. It was then removed from the constant temperature and humidity chamber and visually inspected for any floating, and evaluated according to the following criteria. The punch shape of the mold used was a square with sides of 30 mm, a corner R of 2 mm, and a punch shoulder R of 1 mm, and the die hole shape of the mold used was a square with sides of 34 mm, a die hole corner R of 2 mm, and a die hole shoulder R of 1 mm. S: No floating (very good) A: One of the four sides is lifted (good) B: Two of the four sides are loose (usable) C: Three or more of the four sides are floating (unusable)

[0095] [Impact resistance of molded products] The resulting battery packaging materials were each cut into 80 mm x 80 mm pieces to obtain test pieces. The number of times the resulting test pieces were subjected to a DuPont impact test under conditions of 25°C and 50% relative humidity until they broke was measured, and the test pieces were evaluated according to the following criteria. The DuPont impact test was performed using a hammer with a 1 / 2-inch rounded tip, in which a 300 g weight was dropped freely from a height of 5 cm. S: No breakage even after 10 tests (very good) A: Breaks after 5 to 9 tries (good) B: Breaks after 2-4 tries (usable) C: Broken on the first try (unusable)

[0096] [Table 3]

[0097] The abbreviations in Table 3 are as follows: SC-1: Glycidopropyltrimethoxysilane DBTDL: dibutyltin dilaurate (trade name: U-810, manufactured by Nitto Kasei Co., Ltd.) NCO-1: Trimethylolpropane adduct of tolylene diisocyanate (trade name: Coronate L, manufactured by Tosoh Corporation, non-volatile content 75%, NCO content 13.2%) NCO-2: Nurate form of hexamethylene diisocyanate (trade name: Duranate TMA-100, Asahi Kasei Corporation, non-volatile content 100%, NCO content 23.0%) NCO-3: Nurate form of isophorone diisocyanate (trade name: VESTANAT T1890L, manufactured by Evonik Japan Co., Ltd., non-volatile content 70%, NCO content 12.0%)

[0098] From the results in Table 3, it can be seen that packaging materials using adhesives containing a predetermined range of constituent units derived from polyhydric alcohol (a1) having a melting point of 10 to 50°C have a high adhesive strength when the adhesive is applied in an amount of 2 g / m, regardless of the type of polyhydric alcohol (a1). 2 Even with such a thin film, the adhesive strength, moldability, and moist heat resistance of the molded product were good, and the molded product also showed excellent impact resistance. In particular, Example 2 showed excellent results in all evaluation results because the polyhydric alcohol (a1) having a melting point of 10 to 50°C, the weight average molecular weight of the polyester polyol (A), the [NCO] / [OH] ratio of the adhesive, and the viscoelasticity value of the cured product were all within the optimal ranges.

[0099] On the other hand, in Comparative Example 1, no polyhydric alcohol (a1) was used, and the storage modulus of the cured product at 60°C (Er 60 ) were also low, resulting in poor results in all evaluations. Comparative Example 2 corresponds to an example in WO 2018 / 117080, and the amount of polyhydric alcohol (a1) was excessive, resulting in poor storage stability and difficulty in application. Furthermore, the adhesive layer was hard and brittle, and showed poor adhesive strength and impact resistance. Comparative Example 3 corresponds to an example of Patent Application No. 2021-109351, and since polyhydric alcohol (a1) was not used, the cohesive strength of the adhesive layer was insufficient, resulting in poor impact resistance. In Comparative Example 4, no polyhydric alcohol (a1) was used, and the storage modulus of the cured product at 60°C (Er 60 ) was too high, resulting in poor wettability to the substrate, and poor adhesive strength, moldability, and impact resistance. Comparative Example 5 is (Er 25 -Er 60 ) / Er 60 The adhesive layer showed excessive crystallinity due to the high value, making it hard and brittle, resulting in poor moldability, moist heat resistance, and impact resistance. [Explanation of symbols]

[0100] (1): Outer resin film layer (2):Outer adhesive layer (3):Metal foil layer (4): Inner adhesive layer (5): Heat seal layer

Claims

1. An adhesive for packaging materials for electricity storage devices, comprising at least a polyester polyol (A) and a polyisocyanate (B), the polyester polyol (A) contains 10 to 60 mol % of structural units derived from a polyhydric alcohol (a1) having a melting point of 10 to 50°C, based on the total amount of polyhydric alcohol components; The storage modulus (Er ２５ [MPa]) and storage modulus at 60°C (Er ６０ [MPa]) satisfies the following (i) and (ii): (i) Er ６０ is 50 MPa or more and 1000 MPa or less. (ii) Er ２５ and Er ６０ However, 1≦(Er ２５ -Er ６０ ) / Er ６０ ≦7.

2. 2. The adhesive for packaging materials for electricity storage devices according to claim 1, wherein the polyester polyol (A) contains 10 to 40 mol % of structural units derived from a polyhydric alcohol (a1) having a melting point of 10 to 50°C, based on the total amount of polyhydric alcohol components.

3. 2. The adhesive for packaging materials for electric storage devices according to claim 1, wherein a ratio [NCO] / [OH] of the number of isocyanate groups in the polyisocyanate (B) to the number of hydroxyl groups in the polyester polyol (A) is 5 to 20.

4. 2. The adhesive for packaging materials for electricity storage devices according to claim 1, wherein the polyester polyol (A) has a weight average molecular weight of 50,000 to 100,000.

5. A packaging material for an electricity storage device, comprising an outer layer adhesive layer made of the adhesive for electricity storage device packaging material according to any one of claims 1 to 4, and having a configuration in which at least an outer layer resin film layer (1), an outer layer adhesive layer (2), a metal foil layer (3), an inner layer adhesive layer (4), and a heat seal layer (5) are laminated in this order from the outside.

6. A container for an electricity storage device formed from the packaging material for an electricity storage device according to claim 5, wherein the outer layer side resin film layer (1) forms a convex surface and the heat seal layer (5) forms a concave surface.

7. An electricity storage device comprising the electricity storage device container according to claim 6.

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