Polyurethane adhesive for energy storage device packaging, energy storage device packaging, container for energy storage device, and energy storage device

Abstract

To provide a polyurethane adhesive for energy storage device packaging materials that is excellent in moldability, long-term resistance to humid heat, adhesive strength at room temperature, and storage stability of the main agent solution, and is also reliable in high-temperature environments, exhibiting sufficient adhesive strength even in high-temperature environments; an energy storage device packaging material using the adhesive; an energy storage device container; and an energy storage device. [Solution] A polyurethane adhesive for energy storage device packaging materials, comprising a polyol main component (A) and a polyisocyanate curing agent (B), characterized in that the polyol main component (A) includes a specific polyester polyol (A1) and a specific polyester polyol (A2), which are reaction products or modified products of a polybasic acid or a derivative thereof with a polyhydric alcohol.

Description

Technical Field

[0001] The present invention relates to a polyurethane adhesive for a power storage device packaging material, a power storage device packaging material using the adhesive, a container for a power storage device, and a power storage device.

Background Art

[0002] Due to the rapid growth of electronic devices such as mobile phones and laptop computers, the demand for power storage devices such as secondary batteries like lithium-ion batteries and nickel-metal hydride batteries, and electrochemical capacitors such as electric double layer capacitors has been increasing. Among these, small lithium-ion batteries have attracted attention because of their high energy density and light weight. Conventionally, metal cans have been used as the exterior of lithium-ion batteries, but packaging materials laminated with plastic films, metal foils, etc. are becoming the mainstream from the viewpoints of weight reduction and productivity.

[0003] For example, in Patent Document 1, a battery packaging material using a polyurethane adhesive containing a polyester polyol and a polyisocyanate having different glass transition temperatures in the outer layer adhesive layer has excellent moldability, and even after a long-term durability test under high temperature and high humidity, there is no decrease in the strength between layers, and appearance defects such as floating between layers can be suppressed.

[0004] In Patent Document 2, a two-component curable polyurethane adhesive containing a polyester resin having a specific molecular weight range containing an aliphatic carboxylic acid with an even number of methylene groups in the methylene chain and an aromatic carboxylic acid in a specific ratio and a curing agent is used for a battery packaging material, which has excellent moldability and the heat-resistant resin layer does not peel off even after deep molding.

[0005] In Patent Document 3, a battery packaging material using a polyurethane adhesive in which the equivalent ratio [NCO] / [OH] of the isocyanate groups contained in the curing agent to the total of the hydroxyl groups and carboxyl groups in the main agent containing two polyester polyols having different glass transition temperatures in a specific composition ratio is 10 to 30 is disclosed to be excellent in adhesive strength, moldability, and durability. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2020 / 179609 [Patent Document 2] Japanese Patent Publication No. 2015-024862 [Patent Document 3] Japanese Patent Publication No. 2014-091770 [Overview of the project] [Problems that the invention aims to solve]

[0007] In recent years, as applications such as automotive and home energy storage have expanded, there has been a demand for larger capacity secondary batteries, and packaging materials for energy storage devices require good moldability. Furthermore, for automotive applications, good long-term outdoor durability is required in terms of heat resistance and heat and humidity resistance. From a safety standpoint, the development of polymer-type lithium-ion batteries and all-solid-state batteries is progressing, and by eliminating the low-boiling point carbonate solvent contained in the electrolyte, the required heat resistance temperature has also increased.

[0008] In addition to moldability and long-term heat and humidity resistance, adhesives used in packaging materials for pouch-type energy storage devices require basic adhesive properties such as adhesive strength at room temperature and adhesive strength at high temperatures, such as 120°C. Adhesives that can exhibit the same adhesive strength at 120°C as at room temperature are highly reliable in high-temperature environments and are suitable for use in energy storage devices. Furthermore, using large amounts of highly crystalline materials or mixing resins with different properties to improve adhesive strength and moldability at high temperatures can lead to problems such as clouding over time, reducing product lifespan. Therefore, the storage stability of the main solution is also important.

[0009] The adhesive described in Patent Document 1 sometimes exhibits relatively good physical properties, but it had issues with solution stability.

[0010] The adhesive described in Patent Document 2 is composed only of a polyester resin with a relatively low molecular weight and a polyfunctional isocyanate compound. As a result, the adhesive lacks sufficient cohesive strength, leading to poor laminate strength at 120°C and making it unreliable in high-temperature environments.

[0011] The adhesive described in Patent Document 3 does not fully benefit from phase separation of the cured coating film because there is no molecular weight difference between the two polyester polyol components that make it up. As a result, it has inferior physical properties such as laminate strength at 120°C and its reliability in high-temperature environments cannot be guaranteed.

[0012] Therefore, the present invention aims to provide a polyurethane adhesive for energy storage device packaging materials that is excellent in moldability, long-term resistance to humid heat, adhesive strength at room temperature, and storage stability of the main agent solution, and furthermore, is highly reliable in high-temperature environments, exhibiting sufficient adhesive strength even in high-temperature environments, an energy storage device packaging material using the adhesive, an energy storage device container, and an energy storage device. [Means for solving the problem]

[0013] As a result of diligent research to solve the above problems, we have found that the above problems can be solved by the embodiments shown below, and have completed the present invention.

[0014] In other words, the present invention relates to a polyurethane adhesive containing a polyol main component (A) and a polyisocyanate curing agent (B), The polyol main component (A) comprises polyester polyol (A1) and polyester polyol (A2), which are reaction products or modified products of a polybasic acid or its derivative with a polyhydric alcohol. The present invention relates to a polyurethane adhesive for packaging materials for energy storage devices, characterized by satisfying the following formulas (1) and (2). (1)5,000≦Mn(A1)-Mn(A2)≦40,000 (2)20℃≦Tg(A2)-Tg(A1)≦100℃ Mn(A1): Number average molecular weight of polyester polyol (A1) Mn(A2): Number-average molecular weight of polyester polyol (A2) Tg(A1): Glass transition temperature (°C) of polyester polyol (A1) Tg(A2): Glass transition temperature (°C) of polyester polyol (A2)

[0015] Moreover, it relates to the polyurethane adhesive for the power storage device packaging material, which is characterized by satisfying the following formula. (3) 26000 ≤ Mn(A1) ≤ 50000 (4) 5000 ≤ Mn(A2) ≤ 25000 (5) -30°C ≤ Tg(A1) ≤ 20°C (6) 40°C ≤ Tg(A2) ≤ 80°C

[0016] Moreover, it relates to the polyurethane adhesive for the power storage device packaging material, which is characterized in that the equivalent ratio [NCO] / [OH] of the hydroxyl group contained in the polyol main agent (A) and the isocyanate group contained in the polyisocyanate curing agent (B) is 11 or more and 30 or less.

[0017] Moreover, it relates to the polyurethane adhesive for the power storage device packaging material, in which the content rate of the aromatic polybasic acid or its derivative in 100 mol% of the polybasic acid or its derivative constituting the polyester polyol (A2) is 81 mol% or more, and the content rate of terephthalic acid in 100 mol% of the aromatic polybasic acid or its derivative is 10 mol% or more and 60 mol% or less.

[0018] Moreover, it relates to the polyurethane adhesive for the power storage device packaging material, in which the content ratio of the polyester polyol (A1) in 100 mass% of the polyol main agent (A) is 30 mass% or more and 90 mass% or less, and the content ratio of the polyester polyol (A2) is 10 mass% or more and 60 mass% or less.

[0019] Moreover, it relates to the polyurethane adhesive for the power storage device packaging material, in which the acid value of each of the polyester polyol (A1) and the polyester polyol (A2) is 5 mgKOH / g or less.

[0020] Furthermore, there is provided a power storage device packaging material having a structure in which at least an outer-layer-side resin film layer, an outer-layer-side adhesive layer, a metal foil layer, an inner-layer-side adhesive layer, and a heat seal layer are sequentially laminated. The present invention relates to a power storage device packaging material, wherein the outer-layer-side adhesive layer is a cured product of a polyurethane adhesive for the power storage device packaging material.

[0021] There is provided a container for a power storage device formed from the power storage device packaging material, wherein a convex surface is formed of the outer-layer-side resin film layer and a concave surface is formed of the heat seal layer.

[0022] There is provided a power storage device including the container for a power storage device.

Effects of the Invention

[0023] According to the present invention, there are provided a polyurethane adhesive for a power storage device packaging material, a power storage device packaging material, a container for a power storage device, and a power storage device, which are excellent in moldability, long-term durability, adhesive strength at room temperature, and storage stability of a main agent solution, and further excellent in reliability at high temperatures where sufficient adhesive strength can be exhibited even in a high temperature environment.

Modes for Carrying Out the Invention

[0024] Hereinafter, the polyurethane adhesive for a power storage device packaging material, the power storage device packaging material, the container for a power storage device, and the power storage device of the present invention will be described, but the present invention is not limited thereto. In this specification, "parts" and "%" represent "parts by mass" and "% by mass", respectively, unless otherwise specified. In addition, the numerical range specified using "~" in this specification shall include the numerical values described before and after "~" as the range of the lower limit value and the upper limit value.

[0025] <Polyurethane Adhesive for Power Storage Device Packaging Material> The polyurethane adhesive for energy storage device packaging materials of the present invention contains a polyol main component (A) and a polyisocyanate curing agent (B), wherein the polyol main component (A) includes polyester polyol (A1) and polyester polyol (A2), which are reaction products or modified products of a polybasic acid or its derivative with a polyhydric alcohol. The present invention will be described in detail below.

[0026] <Polyol-based component (A)> The polyol main component (A) comprises polyester polyol (A1) and polyester polyol (A2), which are reaction products or modified products of a polybasic acid or its derivative with a polyhydric alcohol, and is characterized by satisfying the following formulas (1) and (2). (1)5,000≦Mn(A1)-Mn(A2)≦40,000 (2)20℃≦Tg(A2)-Tg(A1)≦100℃ Tg(A1): Glass transition temperature (°C) of polyester polyol (A1) Tg(A2): Glass transition temperature (°C) of polyester polyol (A2) Mn(A1): Number average molecular weight of polyester polyol (A1) Mn(A2): Number average molecular weight of polyester polyol (A2) By containing polyester polyol (A1) and polyester polyol (A2), it exhibits excellent cohesiveness and superior adhesive strength. In the present invention, the polyol main component (A) contains two polyester polyols with different glass transition temperatures and number-average molecular weights. When reacted with the polyisocyanate curing agent (B) to form a cured coating film, rigid and flexible parts separate for the first time. This allows for a high-level balance between substrate wetting and high-temperature cohesiveness, which are usually a trade-off, and is thought to improve adhesive strength, moldability, and long-term durability not only in room temperature environments but also in high-temperature environments. Furthermore, by controlling the glass transition temperature difference between polyester polyol (A1) and polyester polyol (A2) within an appropriate range, the polyol main component (A) in the present invention prevents excessive phase separation, providing a highly reliable energy storage device packaging material, energy storage device container, and energy storage device with excellent solution stability. In this specification, the glass transition temperature (hereinafter also referred to as Tg) can be determined by the method described in the examples.

[0027] Although the mechanism by which the performance of the cured coating film is realized is not certain, the inventors of this invention surmise the following. When preparing a polyol main component (A) by mixing a polyester polyol (A1) with a low Tg and high number-average molecular weight, a polyester polyol (A2) with a high Tg and low number-average molecular weight, and additives, it is thought that a weak phase separation structure, which does not affect the storage stability of the main component solution, is exhibited due to the difference in Tg and number-average molecular weight between polyester polyol (A1) and polyester polyol (A2). Between polyester polyol (A1) with a high number-average molecular weight and polyester polyol (A2) with a low number-average molecular weight, polyester polyol (A2) with a relatively lower number-average molecular weight tends to react more readily with the polyisocyanate curing agent. Since the polyisocyanate curing agent (B) is thought to be uniformly dispersed in a system with weak phase separation, it is presumed that regions with a high concentration of polyester polyol (A1) react less readily with the polyisocyanate curing agent (B) compared to the case where layer separation does not occur. On the other hand, regions with a high concentration of polyester polyol (A2) react more readily with the polyisocyanate curing agent (B) compared to the case where layer separation does not occur. In other words, it is presumed that in regions with a high concentration of polyester polyol (A2), the degree of crosslinking increases, and the effect of rigidity due to crosslinking becomes more pronounced. As a result, it is presumed that only after the coating is cured does a phase separation structure become apparent, consisting of rigid, island-like substructures derived from polyester polyol (A2) and flexible, sea-like substructures derived from polyester polyol (A1). Each plays a role in cohesive force and substrate conformability, enabling the achievement of moldability, long-term durability, and adhesive strength at both room temperature and high-temperature environments, which are usually difficult to balance. Furthermore, it is presumed that the characteristic of weak phase separation before curing makes it possible to provide an adhesive with high storage stability of the main agent solution.

[0028] In 100% by mass of the polyol main component (A), it is preferable that the content ratio of polyester polyol (A1) is 30% by mass or more and 90% by mass or less, and the content ratio of polyester polyol (A2) is 5% by mass or more and 60% by mass or less, and more preferably that the content ratio of polyester polyol (A1) is 35% by mass or more and 85% by mass or less, and the content ratio of polyester polyol (A2) is 10% by mass or more and 55% by mass or less. When the content ratio of polyester polyol (A1) is 30% by mass or more and 90% by mass or less, and the content ratio of polyester polyol (A2) is 5% by mass or more and 60% by mass or less, the adhesive's substrate conformability and cohesive force are both achieved, which is advantageous for the development of adhesive properties.

[0029] [Polyester polyol (A1) and polyester polyol (A2)] The number-average molecular weight of polyester polyol (A1), Mn(A1), and the number-average molecular weight of polyester polyol (A2), Mn(A2), satisfy the above equation (1), where Mn(A1) > Mn(A2). That is, it is important that the difference between Mn(A1) and Mn(A2) is between 5,000 and 40,000, more preferably between 7,000 and 38,000, and even more preferably between 10,000 and 35,000. When the difference between Mn(A1) and Mn(A2) is 5,000 or more, the difference in reactivity between the polyester polyol (A1) and the polyisocyanate curing agent (B) of the polyester (A2) becomes large, the phase separation structure of the cured coating film becomes clear, and the moldability, long-term durability, and adhesion strength under normal temperature and high temperature environments are improved. When the difference between Mn(A1) and Mn(A2) is 40,000 or less, the difference in reactivity does not become too large, and the moldability, long-term durability, and adhesion strength under normal temperature and high temperature environments are improved.

[0030] In addition, it is preferable that the number average molecular weight: Mn(A1) of the polyester polyol (A1) satisfies the following formula (3), and the number average molecular weight: Mn(A2) of the polyester polyol (A2) satisfies the following formula (4). (3) 26,000 ≤ Mn(A1) ≤ 50,000 (4) 5,000 ≤ Mn(A2) ≤ 25,000 When Mn(A1) is 26,000 or more and 50,000 or less, the cohesive force of the polyurethane adhesive is effectively exerted, and when Mn(A2) is 5,000 or more and 25,000 or less, the followability to the substrate is effectively exerted. More preferably, Mn(A1) is 30,000 or more and 45,000 or less, and more preferably, Mn(A2) is 7,000 or more and 23,000 or less.

[0031] The glass transition temperature: Tg(A1) of the polyester polyol (A1) and the glass transition temperature: Tg(A2) of the polyester polyol (A2) satisfy Tg(A1) < Tg(A2) and the above formula (2). That is, it is important that the difference between Tg(A2) and Tg(A1) is 20°C or more and 100°C or less, preferably 25°C or more and 95°C or less, and more preferably 30°C or more and 90°C or less. When the difference between Tg(A2) and Tg(A1) is 20°C or more, a very weak phase separation structure is formed between the polyester polyol (A1) and the polyester polyol (A2), and combined with the above conditions of the number average molecular weight difference, a difference in reactivity with the curing agent can be induced. When the difference between Tg(A2) and Tg(A1) is 100°C or less, the phase separation of the main agent does not become excessive, and the storage stability of the main agent solution can be ensured.

[0032] Furthermore, it is preferable that the glass transition temperature Tg(A1) of polyester polyol (A1) satisfies the following formula (5), and the glass transition temperature Tg(A2) of polyester polyol (A2) satisfies the following formula (6). (5) -30℃≦Tg(A1)≦20℃ (6) 40℃ ≤ Tg(A2) ≤ 80℃ When Tg(A1) is between -30°C and 20°C, the adhesive's ability to conform to the substrate improves, and when Tg(A2) is between 40°C and 80°C, the adhesive's cohesive strength improves. Tg(A1) is more preferably between -25°C and 15°C. Tg(A2) is more preferably between 45°C and 70°C.

[0033] Polyester polyol (A1) and polyester polyol (A2) are reaction products or modified products thereof of polybasic acids or their derivatives with polyhydric alcohols. Polybasic acids include, but are not limited to, aromatic polybasic acids such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and phthalic anhydride; aliphatic polybasic acids such as adipic acid, azelaic acid, sebacic acid, succinic acid, glutaric acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, and itaconic anhydride; or derivatives thereof such as dialkyl esters or mixtures thereof. The polybasic acid component may be used alone or in combination of two or more types.

[0034] Polyhydric alcohols include, but are not limited to, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, butylene glycol, neopentyl glycol, dieopentyl glycol, butylethylpropanediol, 2-methyl-1,3-propanediol, trimethylolpropane, glycerin, 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 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, polyurethane polyol, or mixtures thereof. The polyhydric alcohol component may be used alone or in combination of two or more types.

[0035] It is preferable that the polybasic acid or its derivative contains 50 to 80 mol% aromatic polybasic acid components in 100 mol%. It is preferable that the aromatic polybasic acid components are 50 mol% or more because the cohesive force derived from the aromatic ring is increased and moldability is improved, and that the decrease in adhesiveness is suppressed if they are 80 mol% or less.

[0036] Furthermore, it is preferable that the content of aromatic polybasic acid or its derivative in 100 mol% of the polybasic acid or its derivative constituting the polyester polyol (A2) is 81 mol% or more, and the content of terephthalic acid in 100 mol% of the aromatic polybasic acid or its derivative is 10 mol% or more and 60 mol% or less. When the content of aromatic polybasic acid or its derivative in 100 mol% of the polybasic acid or its derivative is 81 mol% or more, the glass transition temperature of the resin can be effectively improved. Also, when the content of terephthalic acid in 100 mol% of the aromatic polybasic acid or its derivative is 10 mol% or more, the cohesive strength of the adhesive is improved, and the 120°C laminate strength and deep drawing moldability are improved. When it is 60 mol% or less, the solution stability of the main component is improved. A more preferable range for the content of terephthalic acid in 100 mol% of the aromatic polybasic acid or its derivative is 15 mol% or more and 55 mol% or less.

[0037] The acid values ​​of polyester polyol (A1) and polyester polyol (A2) are preferably 5.0 mg KOH / g or less, and more preferably 2.0 mg KOH / g or less. When the acid value of the polyester polyol is 5.0 mg KOH / g or less, the moisture heat resistance of the molded product is improved.

[0038] Polyester polyol (A1) and polyester polyol (A2) may be modified products of the reaction between a polybasic acid or its derivative and a polyhydric alcohol.

[0039] [Modified material: Polyester urethane polyol] Examples of modified polyester polyols include polyols (hereinafter referred to as polyester urethane polyols) obtained by reacting the hydroxyl groups in the polyester polyol, which is a reaction product of the polybasic acid and polyhydric alcohol described above, with polyisocyanate under conditions of excess hydroxyl groups to introduce urethane bonds.

[0040] Examples of the polyisocyanates include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aromatic aliphatic diisocyanates, monomers of trifunctional or more polyisocyanates, and various derivatives derived from the diisocyanates.

[0041] 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.

[0042] Examples of alicyclic diisocyanates include 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,4-bis(isocyanate methyl)cyclohexane, and 1,3-bis(isocyanate methyl)cyclohexane.

[0043] Examples of aromatic diisocyanates include m-phenylenediisocyanate, p-phenylenediisocyanate, 4,4'-diphenyldiisocyanate, 1,5-naphthalenediisocyanate, 4,4'-diphenylmethanediisocyanate, 2,4- or 2,6-tolylenediisocyanate or mixtures thereof, 4,4'-toluidinediisocyanate, dianisidinediisocyanate, and 4,4'-diphenyletherdiisocyanate.

[0044] Examples of aromatic aliphatic diisocyanates include 1,3- or 1,4-xylylene diisocyanate or mixtures thereof, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis(1-isocyanate-1-methylethyl)benzene or mixtures thereof.

[0045] Examples of polyisocyanate monomers with three or more functions include triisocyanates such as triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanatebenzene, and 2,4,6-triisocyanatetoluene; and tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate.

[0046] Various derivatives derived from the diisocyanate include the diisocyanate and 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. Adducts (compounds) of low molecular weight polyols with a molecular weight of less than 200, such as castor oil; dimers of the diisocyanate (also called uretdiones); trimers of the diisocyanate (also called trimers or nurates); biuret compounds; allophanates; polyisocyanates having a 2,4,6-oxadiazinetrione ring obtained from carbon dioxide and the diisocyanate; prepolymers having isocyanate residues (low polymers obtained from diisocyanate and polyols), etc. can be used.

[0047] Among the polyisocyanates constituting polyester urethane polyisocyanate, tolylene diisocyanate, 4,4'-diphenyl diisocyanate, or 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate are preferred from the viewpoint of moldability of the packaging material and heat seal resistance of the modified product.

[0048] The reaction temperature between the polyol containing the polyester polyol and the polyisocyanate to obtain the polyester urethane polyol is preferably in the range of 50°C to 200°C, more preferably in the range of 80°C to 150°C. In the urethane reaction, the molar ratio of isocyanate groups of the polyisocyanate to hydroxyl groups in the polyol containing the polyester polyol (moles of isocyanate groups / moles of hydroxyl groups) is preferably in the range of 0.1 to 0.9, more preferably in the range of 0.3 to 0.8.

[0049] [Modified product: Acid anhydride-modified polyester polyol] Furthermore, as a modified polyester polyol, for example, an acid anhydride-modified polyester polyol may be obtained by reacting some of the hydroxyl groups in the polyester polyol, which is a reaction product of a polybasic acid and a polyhydric alcohol as described above, with an acid anhydride to introduce carboxyl groups.

[0050] [Acid anhydride] Examples of the acid anhydrides include pyromellitic anhydride, mellitic anhydride, trimellitic anhydride, and trimellitic anhydride esters. Examples of trimellitic anhydrides include ester compounds obtained by esterifying an alkylene glycol or alkanetriol having 2 to 30 carbon atoms with trimellitic anhydride. Specifically, ethylene glycol bisanehydrotrimellitate, propylene glycol bisanehydrotrimellitate, and the like can be used.

[0051] [Other polyols] The polyol main component (A) may be polyester polyol (A1), polyester polyol (A2), or conventionally known polyols or short-chain diols in combination, as long as the effects of the present invention are not impaired. Such combinations are permitted. Examples of other polyols include polyether polyols, polycarbonate polyols, acrylic polyols, polybutadiene polyols, polycaprolactone, polyvalerolactone, and polyester polyols obtained by ring-opening polymerization of lactones such as poly(β-methyl-γ-valerolactone). Examples of short-chain diols include the aforementioned polyhydric alcohols, and linear diols such as 1,4-butanediol are preferred in terms of reactivity with isocyanates.

[0052] <Polyisocyanate curing agent (B)> The polyisocyanate curing agent (B) crosslinks with the hydroxyl groups in the polyol main component (A), increasing the molecular weight of the adhesive layer and improving the internal cohesive force that exhibits energy elasticity. Furthermore, since the isocyanate groups in the polyisocyanate curing agent (B) can react with water to form highly cohesive urea bonds, the cohesive force of the adhesive layer can be enhanced by inducing a self-crosslinking reaction during curing. Furthermore, the polyisocyanate curing agent (B) has the effect of improving the interaction with the substrate surface, as described later. In particular, when a substrate that has undergone physical treatment such as corona discharge treatment or chemical treatment such as organic primer is used, the isocyanate groups in the polyisocyanate curing agent (B) and the active hydrogen groups on the substrate surface undergo a chemical reaction, thereby enabling a strong interaction with the substrate. Thus, by using the polyisocyanate curing agent (B), it becomes possible to form a strong adhesive layer, which suppresses the expansion and contraction of the substrate due to rapid environmental changes, and maintains a high level of adhesive strength.

[0053] As the polyisocyanate curing agent (B), those described in the section on [Polyisocyanate] in the above-mentioned [Modified product: Polyester urethane polyol] can be used. Polyisocyanate curing agent (B) may be used alone or in combination of two or more types. In particular, the polyisocyanate curing agent (B) is preferably a nurate of diisocyanate, an adduct obtained by adding trimethylolpropane to diisocyanate, a biuret type, a prepolymer having isocyanate residues (a low polymer obtained from diisocyanate and polyol), a uretdione having isocyanate residues, an allophanate, or a composite thereof, from the viewpoint of adhesion. For automotive energy storage device applications, it is more preferable to select from the group consisting of tolylene diisocyanate and trimethylolpropane adducts, 3-isocyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate, and hexamethylene diisocyanate nurates, from the viewpoint of achieving both excellent high-temperature durability and high cohesive strength and processability.

[0054] The equivalent ratio [NCO] / [OH] of the hydroxyl groups contained in the polyol main component (A) and the isocyanate groups contained in the polyisocyanate curing agent (B) is preferably 11 to 30, more preferably 12 to 28, and even more preferably 13 to 26. When the [NCO] / [OH] ratio is 11 or higher, the molecular weight of the adhesive layer, which is the cured product of the adhesive, can be efficiently increased. This improves the rise of internal cohesive force, resulting in high adhesion and moldability. When it is 30 or lower, the amount of highly polar urethane and urea bonds generated by the crosslinking reaction is appropriately controlled, allowing for a balance between adhesion and the durability of the molded product.

[0055] <Solvent> The polyurethane adhesive for energy storage device packaging materials of the present invention may contain a solvent to adjust the viscosity of the coating solution to an appropriate level when applying the adhesive to the substrate, within a range that does not affect the substrate during the drying process. Examples of solvents include ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester compounds such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and methoxyethyl acetate; ether compounds such as diethyl ether and ethylene glycol dimethyl ether; aromatic compounds such as toluene and xylene; aliphatic compounds such as pentane and hexane; halogenated hydrocarbon compounds such as methylene chloride, chlorobenzene, and chloroform; alcohols such as ethanol, isopropyl alcohol, and n-butanol; and water. These solvents may be used individually or in combination of two or more.

[0056] <Other ingredients> The polyurethane adhesive for energy storage device packaging materials of the present invention may further contain other components, as long as they do not impair the effects of the present invention. Examples of other components include epoxy resins, reaction accelerators, silane coupling agents, phosphoric acid or phosphoric acid derivatives, leveling agents or defoaming agents, and additives. The other components may be blended with either the polyol main component (A) or the polyisocyanate curing agent (B), or they may be blended when mixing them. These optional components may be used individually or in combination of two or more, and are appropriately selected according to the required performance.

[0057] (Epoxy resin) Polyurethane adhesives for energy storage device packaging materials may further contain epoxy resin to improve adhesive strength to metallic materials such as metal foil. In the present invention, the polyol main component (A) contains polyester polyols (A1) and (A2) having a polyester skeleton, so acid may be generated by hydrolysis when subjected to humid and hot conditions. However, by including epoxy resin, the generated acid reacts with the epoxy resin, further improving humid and hot resistance.

[0058] Examples of epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenoxy resin, bisphenol A novolac type epoxy resin, phenol novolac type epoxy resin, cresol novolac type epoxy resin, trishydroxyphenylmethane type epoxy resin, tetrakisphenolethane type epoxy resin, diphenyldiaminomethane type epoxy resin, aminophenol type epoxy resin, biphenyl type epoxy resin, polycyclic aromatic epoxy resin, tetramethylbiphenol type epoxy resin, flexible epoxy resin, hydrogenated bisphenol A type epoxy resin, aliphatic skeleton epoxy resin, and alicyclic skeleton epoxy resin. From the viewpoint of adhesion and durability of molded products, the epoxy resin is preferably at least one selected from the group consisting of novolac-type epoxy resins such as bisphenol A type epoxy resin, bisphenol A novolac type epoxy resin, phenol novolac type epoxy resin, and cresol novolac type epoxy resin, as well as polyfunctional epoxy resins such as trishydroxyphenylmethane type epoxy resin and tetrakisphenolethane type epoxy resin. These epoxy resins may be used individually or in combination of two or more types.

[0059] From the viewpoint of adhesion and durability of the molded product, the epoxy resin preferably has a weight-average molecular weight of 400 to 3,000. From the viewpoint of adhesion and durability of the molded product, the amount of epoxy resin blended is preferably 1 to 50% by mass, based on the solid content mass of the polyol main component (A). If it is 1% by mass or more, the durability of the molded product is effectively improved, and if it is 50% by mass or less, the decrease in the heat seal resistance of the modified molded product is suppressed.

[0060] (Reaction accelerator) Polyurethane adhesives for energy storage device packaging materials may further contain reaction accelerators to promote the urethane reaction. Examples of reaction accelerators include metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimalate; tertiary amines such as 1,8-diazabicyclo(5,4,0)undecene-7, 1,5-diazabicyclo(4,3,0)nonene-5, and 6-dibutylamino-1,8-diazabicyclo(5,4,0)undecene-7; and reactive tertiary amines such as triethanolamine.

[0061] (Silane coupling agent) Polyurethane adhesives for energy storage device packaging materials may further contain a silane coupling agent to improve the adhesive strength to metallic materials such as metal foil. Examples of silane coupling agents include trialksoxysilanes having vinyl groups, such as vinyltrimethoxysilane and vinyltriethoxysilane; trialksoxysilanes having amino groups, such as 3-aminopropyltriethoxysilane and N-(2-aminoethyl)3-aminopropyltrimethoxysilane; and trialksoxysilanes having glycidyl groups, such as 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane and 3-glycidoxypropyltriethoxysilane.

[0062] The silane coupling agent content is preferably 0.1 to 5 parts by mass, more preferably 0.3 to 3 parts by mass, based on the solid content mass of the polyol main component (A). Adding a silane coupling agent within the above range can further improve the adhesive strength to the metal foil.

[0063] (Phosphoric acid or its derivatives) Polyurethane adhesives for energy storage device packaging materials may contain phosphoric acid or phosphoric acid derivatives to improve adhesive strength to metallic materials such as metal foils. The phosphoric acid can be any phosphoric acid having at least one free oxygen acid, such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, subphosphoric acid, etc.; or condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Examples of phosphoric acid derivatives include those obtained by partially esterifying the above-mentioned phosphoric acid with alcohols while retaining 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 phloroglycinol.

[0064] (Leveling agent or defoaming agent) Polyurethane adhesives for energy storage device packaging materials may contain leveling agents or defoaming agents 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-containing polydimethylsiloxane, polyether ester-modified hydroxyl-containing polydimethylsiloxane, acrylic copolymers, methacrylate copolymers, polyether-modified polymethylalkylsiloxane, alkyl acrylate copolymers, alkyl methacrylate copolymers, and lecithin. Examples of known defoaming agents include silicone resins, silicone solutions, and copolymers of alkyl vinyl ethers, alkyl acrylates, and alkyl methacrylates.

[0065] (Additives) Polyurethane adhesives for energy storage device packaging materials may contain known additives as long as they do not impair the effects of the present invention. Examples of additives include inorganic fillers such as silica, alumina, mica, talc, aluminum flakes, and glass flakes, layered inorganic compounds, 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.

[0066] Packaging materials for energy storage devices The polyurethane adhesive for energy storage device packaging materials of the present invention is used to form an adhesive layer of an energy storage device packaging material, and in particular, it can be suitably used as an outer layer adhesive to form the outer layer adhesive layer of an energy storage device packaging material. The present invention provides a power storage device packaging material comprising, at a minimum, an outer layer resin film layer, an outer layer adhesive layer, a metal foil layer, an inner layer adhesive layer, and a heat seal layer, which are sequentially laminated, and the outer layer adhesive layer is characterized in that it is a cured product of the polyurethane adhesive for power storage device packaging material described above.

[0067] [Outer layer resin film layer] The outer resin film layer is not particularly limited, but it is preferable to use a stretched film made of polyamide or polyester. The outer resin film layer may be colored with pigments such as carbon black or titanium dioxide. Furthermore, the non-laminated surface of the outer resin film layer may be coated with a coating agent or slip agent for scratch prevention and electrolyte resistance, or coated with printing ink for aesthetic purposes. The outer resin film layer may also consist of two or more layers of film pre-laminated. The thickness of the outer resin film layer is not particularly limited, but is preferably 12 to 100 μm.

[0068] [Exterior adhesive layer] The outer adhesive layer is the cured polyurethane adhesive for energy storage device packaging materials described above. The amount of outer adhesive applied after drying is 1 to 15 g / m². 2It is preferable that it be to a certain degree.

[0069] [Metal foil layer] The metal foil layer is not particularly limited, but is preferably an aluminum foil layer. The thickness of the metal foil layer is not particularly limited, but is preferably 20 to 80 μm. Furthermore, it is preferable that the surface of the metal foil layer is treated with known anti-corrosion treatments such as chromate phosphate treatment, chromate chromate treatment, trivalent chromium treatment, zinc phosphate treatment, zirconium phosphate treatment, oxidative zirconium treatment, titanium phosphate treatment, hydrofluoric acid treatment, cerium treatment, and hydrotalcite treatment. By treating with anti-corrosion treatment, corrosion and deterioration of the metal foil surface by the electrolyte of the battery can be suppressed. Furthermore, it is preferable that a known organic primer such as phenolic resin, amide resin, acrylic resin, polyvinyl alcohol, or coupling agent is baked onto the metal at a high temperature of about 200°C on the anti-corrosion treated surface. By applying organic primer treatment, the metal foil and the adhesive can be bonded more firmly, and lifting between the metal foil and the adhesive can be further suppressed.

[0070] [Inner layer adhesive layer] The adhesive used to form the inner adhesive layer is not particularly limited, but it is preferable to use an adhesive that does not reduce the adhesive strength between the metal foil layer and the heat seal layer due to the electrolyte of the energy storage device. In addition to the polyurethane adhesive for energy storage device packaging materials of the present invention, known adhesives can be used. The inner adhesive layer can be formed by, for example, applying an adhesive combining polyolefin resin and polyisocyanate, or an adhesive combining polyol and polyisocyanate, to the metal foil layer using a gravure coater or the like, drying the solvent, superimposing a heat seal layer on the adhesive layer under heat and pressure, and then aging it at room temperature or under heating. Alternatively, an adhesive layer can be formed by melt-extruding an adhesive such as acid-modified polypropylene onto a metal foil layer using a T-die extruder, then placing a heat-seal layer on top of the adhesive layer, and bonding the metal foil layer and the heat-seal layer together to form an inner adhesive layer. If both the outer adhesive layer and the inner adhesive layer require aging, a laminate may be obtained in which the outer resin film layer, the uncured outer adhesive layer, the metal foil layer, the uncured inner adhesive layer, and the heat seal layer are laminated in this order from the outside, and then aging may be performed on all of them together.

[0071] [Heat seal layer] The heat seal layer is not particularly limited, but is preferably an unstretched film made of at least one thermoplastic resin selected from the group consisting of 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.

[0072] The method for manufacturing packaging materials for energy storage devices is not particularly limited and can be manufactured by known methods. For example, an intermediate laminate having the configuration of an outer resin film layer / outer adhesive layer / metal foil layer can be obtained by laminating an outer resin film layer and a metal foil layer using the polyurethane adhesive for energy storage device packaging materials of the present invention, and then a heat seal layer can be laminated onto the metal foil layer surface of the intermediate laminate using the inner adhesive (hereinafter referred to as manufacturing method 1). Alternatively, an intermediate laminate having the configuration of a metal foil layer / inner adhesive layer / heat seal layer can be obtained by laminating a metal foil layer and a heat seal layer using an inner adhesive, and then the metal foil layer and outer resin film layer of the intermediate laminate can be laminated using the polyurethane adhesive for energy storage device packaging materials of the present invention (hereinafter referred to as manufacturing method 2).

[0073] In manufacturing method 1, it is preferable to apply the polyurethane adhesive for energy storage device packaging to one side of either the outer layer resin film layer or the metal foil layer substrate, allow the solvent to evaporate, then place the other substrate on top of the uncured outer layer adhesive layer under heat and pressure, and then age at room temperature to less than 100°C to cure the outer layer adhesive layer. If the aging temperature is less than 100°C, thermal shrinkage of the outer layer resin film layer does not occur, so a decrease in breaking elongation and breaking stress that affect molding, and a decrease in molding productivity due to film curl do not occur. Similarly, in manufacturing method 2, the polyurethane adhesive for energy storage device packaging material may be applied to either the outer resin film layer or the metal foil layer surface of the intermediate laminate.

[0074] Methods for forming the outer adhesive layer include 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, microgravure coater, etc.

[0075] ≪Containers for energy storage devices≫ The container for energy storage devices of the present invention has a convex surface composed of an outer resin film layer and a concave surface composed of a heat-seal layer. It can be obtained by using the packaging material for energy storage devices of the present invention and molding it so that the outer resin film layer constitutes a convex surface and the heat-seal layer constitutes a concave surface. In this invention, "concave surface" means a surface having a recess that can accommodate an electrolyte when a flat packaging material for energy storage devices is molded into a tray shape, and "convex surface" means the back surface of the surface having the recess.

[0076] Energy storage devices The energy storage device of the present invention uses the aforementioned energy storage device container and includes, for example, secondary batteries such as lithium-ion batteries, nickel-metal hydride batteries, and lead-acid batteries, as well as electrochemical capacitors such as electric double-layer capacitors. A typical energy storage device comprises a battery element including electrodes, leads extending from the electrodes, and a container for housing them. In the energy storage device of the present invention, the container for the energy storage device is the container for housing the lead. It is used for the following. The container for storage may be formed from a packaging material for energy storage devices with the heat seal layer on the inside, and obtained by overlapping the heat seal layers of two packaging materials facing each other and heat-sealing the periphery of the overlapped packaging materials, or by folding one packaging material and overlapping it, and similarly heat-sealing the periphery of the packaging material. [Examples]

[0077] 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 "%" refer to "parts by mass" and "% by mass" respectively, unless otherwise specified.

[0078] <Measurement of Acid Value (AV)> Approximately 1 g of the sample (polyester polyol solution) was accurately weighed into a stoppered Erlenmeyer flask, and dissolved in 100 ml of a toluene / ethanol mixture (volume ratio: toluene / ethanol = 2 / 1). Phenolphthalein reagent was added as an indicator, and the mixture was held for 30 seconds. The solution was then titrated with 0.1 N alcoholic potassium hydroxide solution until it turned pale pink, and the acid value (mgKOH / g) was determined using the following formula. Acid value (mgKOH / g)=(5.611×a×F) / S However, S: Sample volume (g) a: Amount of 0.1N alcoholic potassium hydroxide solution consumed (ml) F: Titer of 0.1N alcoholic potassium hydroxide solution

[0079] <Measurement of hydroxyl value (OHV)> Approximately 1 g of the sample (polyester polyol, hydroxyl group-containing urethane resin, etc.) was accurately weighed into a stoppered Erlenmeyer flask and dissolved in 100 ml of a toluene / ethanol mixture (volume ratio: toluene / ethanol = 2 / 1). Then, an acetylating agent (a solution of 25 g of acetic anhydride dissolved in pyridine, to a volume of 100 ml) was accurately added, and the mixture was stirred for approximately 1 hour. Phenolphthalein reagent was added as an indicator and the mixture was allowed to stand for 30 seconds. Afterward, the solution was titrated with 0.5 N alcoholic potassium hydroxide solution until it turned pale pink, and the hydroxyl value (mgKOH / g) was determined using the following formula. Hydroxyl value (mgKOH / g) = [{(ba) × F × 28.05} / S] + D However, S: Sample volume (g) a: Amount of 0.5N alcoholic potassium hydroxide solution consumed (ml) b: Amount of 0.5N alcoholic potassium hydroxide solution consumed in the blank experiment (ml) F: Titer of 0.5N alcoholic potassium hydroxide solution D: Acid value (mgKOH / g)

[0080] <Measurement of number-average molecular weight (Mn)> The number-average molecular weight was measured using Showa Denko K.K.'s KF-805L, KF-803L, and KF-802 columns, with a column temperature of 40°C, THF as the eluent, a flow rate of 0.2 ml / min, RI detection, and a sample concentration of 0.02% by mass. The values ​​used were calculated on a standard polystyrene basis.

[0081] <Glass transition temperature (Tg)> The glass transition temperature was measured using a differential scanning calorimeter (DSC). Specifically, approximately 2 mg of the compound to be measured was weighed onto an aluminum pan, the aluminum pan was placed in a DSC measuring holder, and the endothermic peak obtained from the chart under a heating condition of 5°C / min was read. This peak temperature was defined as the glass transition temperature.

[0082] <Identification of polyester composition> The polyester composition was confirmed by NMR. Specifically, the sample was diluted in deuterated chloroform (CDCl3) to approximately 20 wt%, and the polyester composition was identified by measurement using a JEOL ECX-400 under the following conditions. Nuclide: 13C, Measurement mode: NNE, Number of cumulative measurements: 5000, Measurement temperature: Room temperature.

[0083] <Synthesis of polyester polyols> (Polyester polyol (A1-1)) 119.0 parts isophthalic acid, 133.3 parts terephthalic acid, 253.4 parts azelaic acid, 106.7 parts ethylene glycol, 114.5 parts neopentyl glycol, and 73.2 parts 1,6-hexanediol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 12 hours to obtain a polyester polyol with a number-average molecular weight of 38,000, a hydroxyl value of 3.3 mgKOH / g, an acid value of 0.2 mgKOH / g, and a glass transition temperature of -25°C, in a yield of 83.1%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0084] (Polyester polyol (A1-2)) 124.4 parts isophthalic acid, 139.3 parts terephthalic acid, 264.9 parts azelaic acid, 151.7 parts ethylene glycol, and 119.7 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 12 hours to obtain a polyester polyol with a number-average molecular weight of 38,000, a hydroxyl value of 3.1 mg KOH / g, an acid value of 0.3 mg KOH / g, and a glass transition temperature of -15°C, in a yield of 82.7%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0085] (Polyester polyol (A1-3)) 161.5 parts phthalic anhydride, 155.2 parts terephthalic acid, 159.2 parts adipic acid, 97.4 parts ethylene glycol, 167.2 parts neopentyl glycol, and 59.5 parts diethylene glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 12 hours to obtain a polyester polyol with a number-average molecular weight of 38,000, a hydroxyl value of 3.3 mgKOH / g, an acid value of 0.1 mgKOH / g, and a glass transition temperature of 0°C, in a yield of 82.9%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0086] (Polyester polyol (A1-4)) 130.7 parts isophthalic acid, 266.3 parts terephthalic acid, 76.6 parts adipic acid, 43.4 parts ethylene glycol, 145.6 parts neopentyl glycol, 63.1 parts 2-methyl-1,3-propanediol, and 74.3 parts diethylene glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 12 hours to obtain a polyester polyol with a number-average molecular weight of 38,000, a hydroxyl value of 3.2 mg KOH / g, an acid value of 0.3 mg KOH / g, and a glass transition temperature of 15°C, in a yield of 82.6%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0087] (Polyester polyol (A1-5)) 161.5 parts phthalic anhydride, 155.2 parts terephthalic acid, 159.2 parts adipic acid, 97.4 parts ethylene glycol, 167.2 parts neopentyl glycol, and 59.5 parts diethylene glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 11 hours to obtain a polyester polyol with a number-average molecular weight of 30,000, a hydroxyl value of 4.1 mg KOH / g, an acid value of 0.2 mg KOH / g, and a glass transition temperature of 1°C, in a yield of 84.0%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0088] (Polyester polyol (A1-6)) 161.5 parts phthalic anhydride, 155.2 parts terephthalic acid, 159.2 parts adipic acid, 97.4 parts ethylene glycol, 167.2 parts neopentyl glycol, and 59.5 parts diethylene glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 13 hours to obtain a polyester polyol with a number-average molecular weight of 45,000, a hydroxyl value of 2.8 mg KOH / g, an acid value of 0.3 mg KOH / g, and a glass transition temperature of -1°C, in a yield of 82.0%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0089] (Polyester urethane polyol (A1-7)) 161.5 parts of phthalic anhydride, 155.2 parts of terephthalic acid, 159.2 parts of adipic acid, 97.4 parts of ethylene glycol, 167.2 parts of neopentyl glycol, and 59.5 parts of diethylene glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts of tetraisobutyl titanate were added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 12 hours to obtain a polyester polyol with a number-average molecular weight of 30,000 in yield of 82.2%. 100 parts of the obtained polyester and 43 parts of ethyl acetate were placed in a four-necked flask, and the temperature was raised to 85°C. The mixture was stirred until the solution was homogeneous. 0.8 parts of tolylene diisocyanate and 0.02 parts of dibutyltin dilaurate were added, and the reaction was carried out for 4 hours. After the reaction was complete, 59 parts of ethyl acetate were added to obtain a polyester urethane polyol (A1-7) solution with a number-average molecular weight of 38,000, a glass transition temperature of 4.0°C, a hydroxyl value of 3.5 mg KOH / g, and a non-volatile content of 50%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0090] (Polyester polyol (A1-8)) 113.5 parts isophthalic acid, 127.1 parts terephthalic acid, 241.7 parts azelaic acid, 61.0 parts ethylene glycol, 109.2 parts neopentyl glycol, and 147.4 parts 1,6-hexanediol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 12 hours to obtain a polyester polyol with a number-average molecular weight of 38,000, a hydroxyl value of 3.5 mg KOH / g, an acid value of 0.3 mg KOH / g, and a glass transition temperature of -40°C, in a yield of 81.8%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0091] (Polyester polyol (A1-9)) 224.1 parts isophthalic acid, 224.1 parts terephthalic acid, 60.6 parts sebacic acid, 122.8 parts ethylene glycol, and 168.5 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 12 hours to obtain a polyester polyol with a number-average molecular weight of 38,000, a hydroxyl value of 3.3 mg KOH / g, an acid value of 0.4 mg KOH / g, and a glass transition temperature of 47°C, in a yield of 83.4%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0092] (Polyester polyol (A1-10)) 431.3 parts adipic acid and 368.7 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 15,000, a hydroxyl value of 9.1 mg KOH / g, an acid value of 1.3 mg KOH / g, and a glass transition temperature of -25°C, in a yield of 83.2%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 1.

[0093] (Polyester polyol (A2-1)) 224.1 parts isophthalic acid, 224.1 parts terephthalic acid, 60.6 parts sebacic acid, 122.8 parts ethylene glycol, and 168.5 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 15,000, a hydroxyl value of 8.9 mgKOH / g, an acid value of 1.1 mgKOH / g, and a glass transition temperature of 45°C, in a yield of 82.4%. The synthesized resin was measured by 13C-NMR, and the composition (mol%) shown in Table 2 was obtained.

[0094] (Polyester polyol (A2-2)) 250.7 parts isophthalic acid, 225.6 parts terephthalic acid, 30.5 parts sebacic acid, 123.6 parts ethylene glycol, and 169.6 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 15,000, a hydroxyl value of 9.2 mg KOH / g, an acid value of 1.3 mg KOH / g, and a glass transition temperature of 55°C, in a yield of 82.5%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0095] (Polyester polyol (A2-3)) 250.0 parts isophthalic acid, 250.0 parts terephthalic acid, 112.0 parts ethylene glycol, and 188.0 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 15,000, a hydroxyl value of 9.1 mg KOH / g, an acid value of 1.4 mg KOH / g, and a glass transition temperature of 70°C, in a yield of 83.0%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0096] (Polyester polyol (A2-4)) 185.0 parts isophthalic acid, 315.0 parts terephthalic acid, 112.0 parts ethylene glycol, and 188.0 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 16,000, a hydroxyl value of 7.2 mg KOH / g, an acid value of 1.2 mg KOH / g, and a glass transition temperature of 72°C, in a yield of 81.7%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0097] (Polyester polyol (A2-5)) 500.0 parts isophthalic acid, 112.0 parts ethylene glycol, and 188.0 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 15,000, a hydroxyl value of 7.4 mgKOH / g, an acid value of 1.1 mgKOH / g, and a glass transition temperature of 69°C, in a yield of 82.0%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0098] (Polyester polyol (A2-6)) 425.0 parts isophthalic acid, 75.0 parts terephthalic acid, 112.0 parts ethylene glycol, and 188.0 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 14,000, a hydroxyl value of 7.9 mg KOH / g, an acid value of 1.3 mg KOH / g, and a glass transition temperature of 71°C, in a yield of 81.1%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0099] (Polyester polyol (A2-7)) 350.0 parts isophthalic acid, 150.0 parts terephthalic acid, 112.0 parts ethylene glycol, and 188.0 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 15,000, a hydroxyl value of 7.5 mgKOH / g, an acid value of 1.1 mgKOH / g, and a glass transition temperature of 70°C, in a yield of 83.2%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0100] (Polyester polyol (A2-8)) 225.0 parts isophthalic acid, 275.0 parts terephthalic acid, 112.0 parts ethylene glycol, and 188.0 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 15,000, a hydroxyl value of 7.3 mg KOH / g, an acid value of 1.2 mg KOH / g, and a glass transition temperature of 72°C, in a yield of 82.2%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0101] (Polyester polyol (A2-9)) 200.0 parts isophthalic acid, 300.0 parts terephthalic acid, 112.0 parts ethylene glycol, and 188.0 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 16,000, a hydroxyl value of 7.0 mgKOH / g, an acid value of 1.2 mgKOH / g, and a glass transition temperature of 71°C, in a yield of 83.5%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0102] (Polyester polyol (A2-10)) 450.0 parts isophthalic acid, 50.0 parts terephthalic acid, 112.0 parts ethylene glycol, and 188.0 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 14,000, a hydroxyl value of 8.0 mgKOH / g, an acid value of 1.1 mgKOH / g, and a glass transition temperature of 69°C, in a yield of 82.6%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0103] (Polyester polyol (A2-11)) 224.1 parts isophthalic acid, 224.1 parts terephthalic acid, 60.6 parts sebacic acid, 122.8 parts ethylene glycol, and 168.5 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 2 hours to obtain a polyester polyol with a number-average molecular weight of 7,000, a hydroxyl value of 18.5 mg KOH / g, an acid value of 2.3 mg KOH / g, and a glass transition temperature of 47°C, in a yield of 81.9%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0104] (Polyester polyol (A2-12)) 224.1 parts isophthalic acid, 224.1 parts terephthalic acid, 60.6 parts sebacic acid, 122.8 parts ethylene glycol, and 168.5 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 8 hours to obtain a polyester polyol with a number-average molecular weight of 23,000, a hydroxyl value of 5.4 mgKOH / g, an acid value of 0.8 mgKOH / g, and a glass transition temperature of 48°C, in a yield of 81.7%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0105] (Polyester urethane polyol (A2-13)) 224.1 parts isophthalic acid, 224.1 parts terephthalic acid, 60.6 parts sebacic acid, 122.8 parts ethylene glycol, and 168.5 parts neopentyl glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 3 hours to obtain a polyester polyol with a number average molecular weight of 10,000 in yield of 81.2%. 100 parts of the obtained polyester and 43 parts of ethyl acetate were placed in a four-necked flask, and the temperature was raised to 85°C. The mixture was stirred until the solution was homogeneous. 0.8 parts of tolylene diisocyanate and 0.02 parts of dibutyltin dilaurate were added, and the reaction was carried out for 4 hours. After the reaction was complete, 59 parts of ethyl acetate were added to obtain a polyester urethane polyol (A2-13) solution with a number average molecular weight of 15,000, a glass transition temperature of 46.0°C, a hydroxyl value of 8.2 mg KOH / g, and a non-volatile content of 50%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0106] (Polyester polyol (A2-14)) 126.0 parts isophthalic acid, 266.5 parts terephthalic acid, 81.0 parts adipic acid, 43.4 parts ethylene glycol, 145.7 parts neopentyl glycol, 63.1 parts 2-methyl-1,3-propanediol, and 74.3 parts diethylene glycol were charged, and an esterification reaction was carried out at 170-230°C for 10 hours. After distillation of a predetermined amount of water, 0.05 parts tetraisobutyl titanate was added, and the pressure was gradually reduced. A transesterification reaction was carried out at 1.3-2.6 hPa and 230-250°C for 5 hours to obtain a polyester polyol with a number-average molecular weight of 15,000, a hydroxyl value of 9.0 mgKOH / g, an acid value of 1.2 mgKOH / g, and a glass transition temperature of 15°C, in a yield of 83.1%. The synthesized resin was measured by 13C-NMR and identified as having the composition (mol%) shown in Table 2.

[0107] [Table 1]

[0108] [Table 2]

[0109] The abbreviations used in Tables 1 and 2 are as follows: PA: Phthalic anhydride IPA: Isophthalic Acid TPA: Terephthalic acid AdA: Adipic acid SeA: Sebacinic acid AzA: Azelaic acid EG: Ethylene glycol NPG: Neopentyl Glycol MPO:2-methyl-1,3-propanediol DEG: Diethylene glycol 1,6-HD:1,6-Hexanediol TDI: Tolylene diisocyanate (Coronate T-80 (product name), manufactured by Tosoh Corporation, NCO content 48.2%)

[0110] <Manufacturing of adhesives for energy storage devices> [Example 1] A polyol main component was prepared by mixing 70 parts polyester (A1-1) and 30 parts polyester (A2-3). To this, 3 parts JER-834 (manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin) and 1 part KBM-403 (manufactured by Shin-Etsu Chemical Co., Ltd., silane coupling agent) were added. The mixture was then diluted with ethyl acetate to a non-volatile content of 50% and stirred for 10 hours to obtain the main component solution. The obtained main component solution and CAT-10L (manufactured by Toyo Morton Co., Ltd., aromatic polyisocyanate, solid content concentration 52.5%) were charged at a solid content ratio of 104:35, and diluted with ethyl acetate to prepare a polyurethane adhesive with a solid content concentration of 25%.

[0111] [Examples 2-29, Comparative Examples 1-3] The main component solution and polyurethane adhesive were prepared in the same manner as in Example 1, except that the formulation was changed as shown in Tables 3-5.

[0112] [Evaluation of storage stability of the main solution] The main solution was left to stand at room temperature, and the occurrence of turbidity was visually confirmed. The time until turbidity occurred was evaluated according to the following criteria. S: No turbidity occurs for more than one year after preparation (very good) A: Turbidity occurs between six months and one year after preparation (good) B: Turbidity occurs between 3 months and 6 months after preparation (usable). C: Turbidity develops within 3 months of preparation (unusable).

[0113] [Manufacturing of packaging materials for energy storage devices] On one side of a 40μm thick aluminum foil, a coating-type phosphate chromate treatment agent (Surfcoat NR-X, manufactured by Nippon Paint Co., Ltd.) was applied at a rate of 0.03g / m². 2The material was coated and baked at 230°C. Then, using a dry laminator, the obtained polyurethane adhesive for energy storage devices was applied to the surface-treated aluminum foil as an outer adhesive layer. After the solvent evaporated, a 25 μm thick stretched polyamide film was laminated to obtain an intermediate laminate. The amount of polyurethane adhesive applied after drying was 3 g / m². 2 That's what I decided. Next, using a dry laminator, the adhesive for the inner layer adhesive (described later) was applied to the other side of the aluminum foil of the obtained intermediate laminate. After the solvent evaporated, an unstretched polypropylene film with a thickness of 25 μm was laminated to obtain a laminate. The amount of adhesive applied after drying was 3 g / m². 2 That's what I decided. Next, the packaging material for energy storage devices was subjected to aging at 60°C for 5 days to cure the adhesive layers on the outer and inner sides, thereby obtaining a packaging material for energy storage devices having the following configuration: outer resin film layer / outer adhesive layer / metal foil layer / inner adhesive layer / heat seal layer.

[0114] (Adhesive for the inner layer adhesive) AD-502 (polyester polyol manufactured by Toyo Morton Co., Ltd.) was used as the main component and CAT-10L (isocyanate-based curing agent manufactured by Toyo Morton Co., Ltd.) was used as the curing agent. The mixture was formulated so that the main component / curing agent ratio was 100 / 10 (by mass), and the solid content concentration was adjusted to 25% with ethyl acetate. This mixture was then used as the adhesive for the inner layer adhesive.

[0115] <Rating> The following evaluations were performed on the obtained packaging materials for energy storage devices. The results are shown in Table 2.

[0116] [25℃ Lamination Strength] Packaging material 1 for energy storage devices was cut to a size of 200 mm x 15 mm, and a T-type peel test was performed using a tensile testing machine 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 25°C at a load speed of 50 mm / min, and the average value of three test pieces was evaluated according to the following criteria. S: Average peel strength of 5.0 N or higher (very good) A: Average peel strength is 4.0 N or higher, but less than 5.0 N (good). B: Average peel strength is 3.0 N or higher, but less than 4.0 N (usable). C: Average peel strength is less than 3.0 N (Not usable)

[0117] [Lamination strength at 120℃] Packaging material 1 for energy storage devices was cut to a size of 200 mm x 15 mm, and a T-type peel test was performed using a tensile testing machine 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 120°C at a load speed of 50 mm / min, and the average value of three test pieces was evaluated according to the following criteria. S: Average peel strength of 5.0 N or higher (very good) A: Average peel strength is 4.0 N or higher, but less than 5.0 N (good). B: Average peel strength is 3.0 N or higher, but less than 4.0 N (usable). C: Average peel strength is less than 3.0 N (Not usable)

[0118] [Deep drawing moldability] 0.02 g / m² of erucate amide is applied to both sides of the packaging material 1 for energy storage devices. 2 After coating, the material was cut to a size of 60 mm x 60 mm to form blanks. With the stretched polyamide film facing outwards, the blanks were subjected to a single-stage molding process using a straight mold with no molding height restrictions. The moldability was evaluated according to the following criteria, based on the maximum molding height at which no breakage of the aluminum foil or lifting between layers occurred. The punch shape of the mold used was a square with sides of 29.4 mm, corner radius of 1 mm, and punch shoulder radius of 1 mm. The die hole shape of the mold used was a square with sides of 30.0 mm, die hole corner radius of 1 mm, die hole shoulder radius of 1 mm, and the clearance between the punch and the die hole was 0.3 mm. This clearance causes a slope corresponding to the molding height. The following four stages of evaluation were performed according to the molding height. S: Maximum molded height is 7mm or more (very good) A: Maximum molded height is 6mm or more and less than 7mm (good) B: Maximum molding height is 5mm or more and less than 6mm (usable) C: Maximum molding height is less than 5mm (unusable)

[0119] [Moist heat durability of molded products (long-term moist heat durability test)] Packaging material 1 for energy storage devices was cut to a size of 60 mm x 60 mm to create a blank. With the stretched polyamide film facing outwards, the blank was molded in one stage with a molding height of 5 mm using a straight mold with no molding height restrictions, to obtain a molded product. Three molded products were produced. Next, the three molded products were placed in a constant temperature and humidity chamber at 85°C and 85% RH, and after 500 hours, they were removed from the chamber and visually inspected for any floating, and evaluated according to the following criteria. S: 0 samples with floating (very good) A: One sample showed floating (good). B: Two samples with floating characteristics are available (usable). C: Three samples showed signs of floating (unusable).

[0120] [Table 3]

[0121] [Table 4]

[0122] [Table 5]

[0123] According to the results in Tables 3-5, the polyurethane adhesive for energy storage devices of the present invention, when the difference in the number-average molecular weight and the difference in the glass transition temperature of the polyester polyols (A1) and (A2) contained in the polyol main component (A) falls within a predetermined range, is found to achieve both good storage stability of the main component solution and good performance as an adhesive.

Claims

1. A polyurethane adhesive containing a polyol main component (A) and a polyisocyanate curing agent (B), The polyol main component (A) comprises polyester polyol (A1) and polyester polyol (A2), which are reaction products or modified products of a polybasic acid or its derivative with a polyhydric alcohol. A polyurethane adhesive for energy storage device packaging materials, characterized by satisfying the following formulas (1) and (2). (1) 5,000≦Mn(A1)-Mn(A2)≦40,000 (2) 20℃≦Tg(A2)-Tg(A1)≦100℃ Mn(A1): Number average molecular weight of polyester polyol(A1) Mn(A2): Number average molecular weight of polyester polyol(A2) Tg(A1): Glass transition temperature (°C) of polyester polyol (A1) Tg(A2): Glass transition temperature (°C) of polyester polyol (A2)

2. A polyurethane adhesive for energy storage device packaging material according to claim 1, characterized in that it satisfies the following formula. (3) 26,000≦Mn(A1)≦50,000 (4) 5,000≦Mn(A2)≦25,000 (5) -30℃≦Tg(A1)≦20℃ (6) 40℃≦Tg(A2)≦80℃

3. The polyurethane adhesive for energy storage device packaging materials according to claim 1, characterized in that the equivalent ratio [NCO] / [OH] of the hydroxyl groups contained in the polyol main component (A) and the isocyanate groups contained in the polyisocyanate curing agent (B) is 11 or more and 30 or less.

4. The polyurethane adhesive for energy storage device packaging material according to claim 1, wherein the content of aromatic polybasic acid or its derivative in 100 mol% of the polybasic acid or its derivative constituting the polyester polyol (A2) is 81 mol% or more, and the content of terephthalic acid in 100 mol% of the aromatic polybasic acid or its derivative is 10 mol% or more and 60 mol% or less.

5. The polyurethane adhesive for energy storage device packaging material according to claim 1, wherein the content ratio of polyester polyol (A1) is 30% by mass or more and 90% by mass or less in 100% by mass of polyol main component (A), and the content ratio of polyester polyol (A2) is 5% by mass or more and 60% by mass or less.

6. The polyurethane adhesive for energy storage device packaging material according to claim 1, wherein the acid value of each of the polyester polyol (A1) and polyester polyol (A2) is 5.0 mg KOH / g or less.

7. A storage device packaging material having a configuration in which at least an outer layer resin film layer, an outer layer adhesive layer, a metal foil layer, an inner layer adhesive layer, and a heat seal layer are sequentially laminated, A storage device packaging material wherein the outer adhesive layer is a cured product of the polyurethane adhesive for storage device packaging material described in any one of claims 1 to 6.

8. A container for an energy storage device formed from the energy storage device packaging material described in claim 7, wherein the convex surface is composed of an outer layer resin film layer and the concave surface is composed of a heat seal layer.

9. An energy storage device comprising a container for an energy storage device as described in claim 8.

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