Packaging material for power storage element, container for power storage element, and power storage element

Abstract

The present application provides a power storage element packaging material, a power storage element container, and a power storage element, which have excellent formability and do not cause appearance defects such as interlayer lifting, even when the adhesive is a film, and in which the interlayer adhesive strength is not reduced after a high-temperature high-humidity / long-term durability test. The problem can be solved by a power storage element packaging material including a structure in which, from the outside, an outer layer-side resin film layer (1), an outer layer-side adhesive layer (2), a metal foil layer (3), an inner layer-side adhesive layer (4), and a heat-seal layer (5) are sequentially stacked, the outer layer-side adhesive layer (2) is formed of a polyurethane adhesive containing a main agent (A) and a hardening agent, the main agent (A) includes a polyurethane resin (a) having a hydroxyl group, and the hardening agent includes a polyisocyanate component (B).

Description

Technical Field

[0001] This disclosure relates to a packaging material for energy storage components, used to form containers for energy storage components such as lithium-ion batteries, and to a packaging material for energy storage components with a good appearance and excellent adhesive strength and formability, a container for energy storage components and an energy storage component made using the packaging material. Background Technology

[0002] The rapid development of electronic devices such as mobile phones and portable personal computers has led to a continuous increase in demand for energy storage components such as lithium-ion batteries, nickel-metal hydride batteries, and electrochemical capacitors such as double-layer capacitors. Among these, small lithium-ion batteries have attracted much attention due to their high energy density and lightweight nature. While metal cans have traditionally been used as the outer casing for lithium-ion batteries, packaging materials made of laminated plastic films or metal foils are gradually becoming the mainstream from a lightweight and production efficiency perspective.

[0003] Patent Document 1 discloses a battery casing material having a structure in which a heat-resistant extended resin layer, an adhesive layer, an aluminum layer and a thermoplastic unextended resin layer are sequentially stacked. The adhesive layer comprises a cured adhesive composition containing a polyester resin exhibiting a glass transition temperature of -20°C to 45°C and a toluene diisocyanate-based curing agent in amounts of 10 to 70 parts by mass relative to 100 parts by mass of the polyester resin.

[0004] In addition, Patent Document 2 discloses a battery packaging material, which is formed by sequentially stacking an outer side resin film layer, an outer side adhesive layer, a metal foil layer, an inner side adhesive layer and a heat-sealing layer. The outer side adhesive layer is formed by an adhesive comprising two polyester polyols, polyisocyanate and silane coupling agent having specific glass transition temperatures.

[0005] Additionally, Patent Document 3 describes a battery packaging material that uses an adhesive with a dry coating amount of 4 g / m³. 2 The amount of adhesive used to bond the outer side substrate layer and the metal foil layer together is such that the adhesive comprises a polyol composition obtained by chain elongation of polyester polyol using polyisocyanate and a polyisocyanate composition.

[0006] Patent document 4 discloses a laminating adhesive that limits the content of urethane bonds and isocyanate groups in order to improve processability or improve the formability, moisture and heat resistance and appearance of composite films.

[0007] [Existing Technical Documents]

[0008] [Patent Literature]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2013-149562

[0010] [Patent Document 2] Japanese Patent Application Publication No. 2014-091770

[0011] [Patent Document 3] International Publication No. 2018 / 117080

[0012] [Patent Document 4] Japanese Patent Application Publication No. 2016-196580 Summary of the Invention

[0013] [The problem the invention aims to solve]

[0014] In recent years, with the expansion of applications such as automotive and home energy storage, there is a growing demand for larger capacity rechargeable batteries, as well as for packaging materials for energy storage components that require good formability. In addition, automotive applications require further weight reduction, and even if the adhesive is made into a thin film, it is required that the interlayer adhesive strength of the various plastic films or metal foils in the packaging material be maintained after molding and long-term durability testing, and that there be no abnormal appearance.

[0015] However, the packaging materials described in Patent Documents 1 and 2 use urethane-based adhesives with an excessive amount of isocyanate in the adhesive layer. As a result, the excess isocyanate groups react with water to form a resin with urea bonds. Since the urea-bonded resin has poor compatibility with the urethane-based adhesive, there is a problem that the packaging materials may have poor appearance or be difficult to deep mold when they are made.

[0016] The packaging material described in Patent Document 3 does not use polyurethane resin with specific structural components and urethane bond concentration, thus presenting challenges in simultaneously achieving thin-film properties of the adhesive, moldability, and interlayer adhesive strength after high-temperature and high-humidity / long-term durability tests. Furthermore, it suffers from poor solubility in solvents such as ethyl acetate, leading to the main agent solidifying during long-term storage and making stable coating impossible.

[0017] Patent document 4 describes a laminated adhesive using a polyurethane resin with a limited content of urethane bonds and isocyanates, but it has the problem of low storage elastic modulus and difficulty in forming a film.

[0018] Therefore, the purpose of this disclosure is to provide a packaging material for a storage device that, even when the adhesive is a thin film, does not reduce the interlayer bonding strength after a high temperature and high humidity / long-term durability test, has excellent formability and does not produce appearance defects such as interlayer lifting, a container for a storage device made using the packaging material, and a storage device with excellent reliability.

[0019] [Technical means to solve the problem]

[0020] Through repeated efforts to solve the aforementioned problem, it was discovered that the problem can be solved through the implementation methods shown below, thereby completing this disclosure.

[0021] One embodiment of this disclosure relates to a packaging material for an energy storage element, comprising, from the outside, at least sequentially stacked an outer side resin film layer (1), an outer side adhesive layer (2), a metal foil layer (3), an inner side adhesive layer (4), and a heat-sealing layer (5). In the packaging material for the energy storage element, the outer side adhesive layer (2) is formed of a polyurethane adhesive containing a main agent (A) and a hardener. The main agent (A) comprises a polyurethane resin (a) having hydroxyl groups, and the hardener comprises a polyisocyanate component (B). The polyurethane resin (a) having hydroxyl groups is a reaction product of a polyester polyol and a polyisocyanate, and the ester bond concentration is 9.20 mmol / g to 10.50 mmol / g.

[0022] Another embodiment of this disclosure relates to packaging material for the energy storage element, wherein the urethane bond concentration of the hydroxyl-containing polyurethane resin (a) is 0.10 mmol / g to 0.90 mmol / g.

[0023] Another embodiment of this disclosure relates to packaging material for the energy storage element, wherein the hydroxyl value of the polyurethane resin (a) having hydroxyl groups is 0.5 mg KOH / g to 20 mg KOH / g.

[0024] Another embodiment of this disclosure relates to packaging material for the energy storage element, wherein the hydroxyl-containing polyurethane resin (a) is a reaction product of a polyester polyol with a weight average molecular weight of 5,000 to 30,000 and a polyisocyanate.

[0025] Another embodiment of this disclosure relates to a container for an energy storage element, which is formed from the packaging material for the energy storage element, wherein the outer resin film layer (1) of the container for the energy storage element forms a convex surface and the heat-sealing layer (5) forms a concave surface.

[0026] Another embodiment of this disclosure relates to an energy storage element, which includes a container for the energy storage element.

[0027] [The effects of the invention]

[0028] In this disclosure, by using a main agent with a predetermined ester bond concentration and excellent storage stability, an adhesive layer with few coating defects can be obtained. It can also provide packaging materials for energy storage components that do not reduce the interlayer bonding strength even when the adhesive is a thin film after high temperature and high humidity / long-term durability tests, have excellent formability and do not produce appearance defects such as interlayer lifting, containers for energy storage components made using the packaging materials, and energy storage components with excellent reliability. Attached Figure Description

[0029] Figure 1 This is a schematic cross-sectional view of the packaging material for the energy storage components disclosed herein.

[0030] Figure 2 This is a schematic perspective view of one form (tray-shaped) of the container for the energy storage element disclosed herein.

[0031] [Explanation of Symbols]

[0032] (1): Outer side resin film layer

[0033] (2): Outer side adhesive layer

[0034] (3): Metal foil layer

[0035] (4): Inner side adhesive layer

[0036] (5): Heat sealing layer Detailed Implementation

[0037] Packaging materials for energy storage components

[0038] The packaging material for energy storage components disclosed herein comprises, from the outside, at least sequentially stacked an outer-side resin film layer (1), an outer-side adhesive layer (2), a metal foil layer (3), an inner-side adhesive layer (4), and a heat-sealing layer (5). In the packaging material for energy storage components, the outer-side adhesive layer (2) is formed of a polyurethane adhesive containing a main agent (A) and a hardener. The main agent (A) comprises a hydroxyl-containing polyurethane resin (a), and the hardener comprises a polyisocyanate component (B). The hydroxyl-containing polyurethane resin (a) is a reaction product of a polyester polyol and a polyisocyanate, and the ester bond concentration is 9.20 mmol / g to 10.50 mmol / g. Hereinafter, preferred embodiments will be described in detail as examples of the present disclosure.

[0039] <Outer side adhesive layer (2)>

[0040] The outer side adhesive layer (2) of this disclosure is formed of a polyurethane adhesive containing a main agent (A) and a hardener, wherein the main agent (A) comprises a polyurethane resin (a) having hydroxyl groups, and the hardener comprises a polyisocyanate component (B). First, the main agent will be described. The main agent and the hardener may also contain additives without impairing the effects of this disclosure.

[0041] <Polyurethane resin with hydroxyl groups (a)>

[0042] The hydroxyl-containing polyurethane resin (a) is a product of the reaction between a polyester polyol and a polyisocyanate, and the ester bond concentration is 9.20 mmol / g to 10.50 mmol / g. The hydroxyl-containing polyurethane resin (a) can be obtained by urethane esterification of the hydroxyl groups in a polyol containing a polyester polyol (described later) with the isocyanate groups in the polyisocyanate under conditions of excess hydroxyl groups.

[0043] (Polyester polyols)

[0044] Polyester polyols are not limited to the following, but may include, for example, polyester polyols obtained by reacting a carboxylic acid component with a hydroxyl component. Examples of said carboxylic acid components include, for example, diacids having an aromatic ring such as terephthalic acid, isophthalic acid, naphthalic acid, and phthalic anhydride; aliphatic diacids such as adipic acid, azelaic acid, sebacic acid, succinic acid, glutaric acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, and itaconic anhydride; or dialkyl esters of these or mixtures thereof. Examples of the hydroxyl components include, for example, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, butanediol, neopentyl glycol, dinepentyl glycol, trimethylolpropane, glycerol, 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanediol, 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, and other diols; or mixtures thereof. The carboxylic acid component and the hydroxyl component may each be used individually, but preferably two or more are used in combination.

[0045] Based on the total carboxylic acid composition, the carboxylic acid composition is preferably composed of 5 mol% to 50 mol% aliphatic diacid. If the amount of aliphatic diacid is 5 mol% or more, the solvent solubility is improved, and the resulting polyester polyol solution has a lower viscosity. This improves the coatability of the polyurethane adhesive, resulting in packaging materials with a superior appearance. If it is 50 mol% or less, the glass transition temperature of the polyester polyol can be easily adjusted, further improving the adhesive strength. From the same perspective, based on the total carboxylic acid composition, the amount of aliphatic diacid is more preferably 25 mol% to 50 mol%.

[0046] The ester bond concentration of the polyester polyol is preferably 9.40 mmol / g to 10.80 mmol / g, more preferably 9.40 mmol / g to 10.3 mmol / g, and even more preferably 9.40 mmol / g to 9.80 mmol / g. If the ester bond concentration of the polyester polyol is 9.40 mmol / g or higher, it exhibits excellent solubility in ester-based solvents such as ethyl acetate, and the amount of isocyanate used for urethane esterification is not limited, thus providing good adhesion, which is preferable. If it is 10.80 mmol / g or lower, it can suppress high viscosity or decrease in solvent solubility caused by intermolecular interactions based on ester bonds, which is also preferable.

[0047] The ester bond concentration of polyester polyols can be calculated using the following formula.

[0048] Formula: Polyester bond concentration (mmol / g) = (Molar amount of carboxylic acid component added × Sum of functional groups of carboxylic acid) / (Total amount added × Solid yield) × 1000

[0049] Taking the polyester from Synthetic Example 1 as an example,

[0050] Isophthalic acid (functional group 2): 148g = 0.892mol

[0051] Terephthalic acid (functional group 2): 296g = 1.783mol

[0052] Adipic acid (functionality 2): 260g = 1.780mol

[0053] Total fill weight 1000.05g, yield 83.9%.

[0054] The ester bond concentration of polyester 1 can be calculated as (0.892×2+1.783×2+1.780×2) / (1000.5*0.839)×1000=10.63.

[0055] The weight average molecular weight of the polyester polyol is preferably 5,000 to 30,000, more preferably 10,000 to 30,000, and even more preferably 15,000 to 25,000. If the weight average molecular weight is 5,000 or higher, the adhesion to the substrate is further improved, and the processability is excellent. If the weight average molecular weight is 30,000 or lower, it is easy to prevent the concentration of hydroxyl groups at the end of the polyester polyol from becoming too low, and when reacting with the polyisocyanate described later to obtain a polyurethane resin (a) with hydroxyl groups, it is easy to prevent the reaction time from becoming too long.

[0056] As a polyol constituting the polyurethane resin (a) having hydroxyl groups, polyols other than the polyester polyol may be used in combination. Among the polyols that can be used in combination, examples of hydroxyl components that can be used to synthesize the polyester polyol are neopentyl glycol or 1,4-butanediol, which are preferably used.

[0057] (Polyisocyanate)

[0058] Examples of polyisocyanates constituting a polyurethane resin (a) having hydroxyl groups include: aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aromatic aliphatic diisocyanates, monomers of polyisocyanates with trifunctionality or higher, and various derivatives derived from said diisocyanates.

[0059] Examples of aliphatic diisocyanates include: trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylidene diisocyanate, 1,2-butylidene diisocyanate, 2,3-butylidene diisocyanate, 1,3-butylidene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate or 2,2,4-trimethylhexamethylene diisocyanate, and 2,6-diisocyanate methylhexanoate.

[0060] Examples of alicyclic diisocyanates include: 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate, 4,4'-methylene bis(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.

[0061] 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-toluene diisocyanate or 2,6-toluene diisocyanate or mixtures thereof, 4,4'-toluidine diisocyanate, anisidine diisocyanate, and 4,4'-diphenyl ether diisocyanate.

[0062] Examples of aromatic aliphatic diisocyanates include, for example, 1,3-xylene diisocyanate or 1,4-xylene diisocyanate or mixtures thereof, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,3-bis(1-isocyanate-1-methylethyl)benzene or 1,4-bis(1-isocyanate-1-methylethyl)benzene or mixtures thereof.

[0063] Examples of polyisocyanate monomers with trifunctionality or higher include: triphenylmethane-4,4',4”-triisocyanate, 1,3,5-triisocyanate benzene, 2,4,6-triisocyanate toluene, etc.; and tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate.

[0064] As various derivatives derived from the diisocyanate, the following can be used: adducts (additives) of the diisocyanate with low molecular weight polyols with a molecular weight of less than 200, such as ethylene glycol, propylene glycol, butanediol, hexanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolpropane, cyclohexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol, or castor oil; trimers of the diisocyanate (also called trimers, urate esters); biuret esters; urethane esters; in addition, polyisocyanates having a 2,4,6-oxadiazine trione ring obtained by reacting carbon dioxide with the diisocyanate can also be used.

[0065] The polyisocyanate constituting the polyurethane resin (a) having hydroxyl groups is preferably an aromatic isocyanate or an alicyclic diisocyanate. From the viewpoint of moldability or adhesion after high temperature and high humidity tests, toluene diisocyanate, 4,4'-diphenyl diisocyanate, or 3-isocyanate methyl-3,5,5-trimethylcyclohexyl isocyanate is more preferred.

[0066] The reaction temperature between the polyol and polyisocyanate when obtaining the polyurethane resin (a) with hydroxyl groups is preferably 50°C to 200°C, more preferably 80°C to 150°C. During the urethane esterification reaction, the molar ratio (number of moles of isocyanate groups / number of moles of hydroxyl groups) of the polyisocyanate to the hydroxyl groups in the polyol is preferably 0.1 to 0.9, more preferably 0.3 to 0.8.

[0067] In this disclosure, it is important that the ester bond concentration of the hydroxyl-containing polyurethane resin (a) constituting the outer side adhesive layer is in the range of 9.20 mmol / g to 10.50 mmol / g. By controlling the ester bond concentration within a predetermined range, the stability of the adhesive in solution and its affinity to the substrate based on the ester bonds are suppressed, resulting in excellent coatability. Consequently, the resulting packaging material does not experience a decrease in interlayer adhesive strength after high temperature and humidity / long-term durability testing, exhibits excellent formability, and does not produce appearance defects such as interlayer lifting. Moreover, the aforementioned effect is also significantly observed when the adhesive is applied at a low amount, i.e., when the thickness of the outer side adhesive layer is small. If the ester bond concentration is less than 9.20 mmol / g, the solubility in ester-based solvents such as ethyl acetate decreases, leading to reduced coatability. Alternatively, the affinity to the substrate based on the ester bonds decreases, resulting in reduced adhesive strength. If the concentration exceeds 10.50 mmol / g, the intermolecular interactions based on ester bonds increase, leading to high viscosity or reduced solvent solubility, resulting in a deterioration in appearance after aging due to coating defects. The ester bond concentration of the polyurethane resin (a) with hydroxyl groups is preferably 9.20 mmol / g to 10.1 mmol / g, more preferably 9.20 mmol / g to 9.60 mmol / g.

[0068] The ester bond concentration of polyurethane resin (a) with hydroxyl groups can be calculated using the following formula.

[0069] Calculation formula: Polyester bond concentration (mmol / g) = Polyester bond concentration of polyester polyol × Ratio of polyester polyol to the total mass of polyol and polyisocyanate constituting urethane resin (mass%)

[0070] For example, the ester bond concentration of the polyurethane resin (a) with hydroxyl groups shown in Synthesis Example (a)-1 becomes

[0071] Polyester bond concentration = 10.63 × (100 / 102) = 10.42 mmol / g.

[0072] The urethane bond concentration of the hydroxyl-containing polyurethane resin (a) is preferably in the range of 0.10 mmol / g to 0.90 mmol / g, more preferably 0.15 mmol / g to 0.60 mmol / g, and even more preferably 0.20 mmol / g to 0.40 mmol / g. A concentration of 0.10 mmol / g or higher results in excellent improved compatibility, appearance, and adhesion, and is therefore preferred. A concentration of 0.90 mmol / g or lower prevents the urethane bond concentration from becoming excessively high, resulting in a suitable viscosity and excellent coatability and appearance, and is therefore preferred. By controlling the urethane bond concentration of the hydroxyl-containing polyurethane resin (a), compatibility with the polyisocyanate component (B) as a curing agent can be improved, and an adhesive layer with high crosslinking density and excellent durability and appearance can be formed.

[0073] The concentration of urethane bonds can be calculated using Equation 1 below.

[0074] Formula 1: Carbamate bond concentration (mmol / g) = [(NCO content of polyisocyanate (mass%) ÷ 100) × (the blending ratio of polyisocyanate (mass%) to the total mass of polyols and polyisocyanates constituting the carbamate resin) ÷ 42 × 1000] + [(number of carbamate bonds within the polyisocyanate ÷ molecular weight of the polyisocyanate) × (the blending ratio of polyisocyanate (mass%) to the total mass of polyols and polyisocyanates constituting the carbamate resin) × 1000]

[0075] For example, since the NCO content of toluene diisocyanate is 48.2% by mass, the amount of polyisocyanate added relative to the polyol is 1% by mass, and the number of internal urethane bonds is zero, the urethane bond concentration of the hydroxyl-containing polyurethane resin (a) shown in Synthesis Example (a)-1 becomes

[0076] Carbamate bond concentration = 0.482 × (2 / 102) / 42 × 1000

[0077] =0.23mmol / g.

[0078] The weight-average molecular weight of the hydroxyl-containing polyurethane resin (a) is preferably 20,000 to 100,000, more preferably 40,000 to 70,000. If the weight-average molecular weight is 20,000 or higher, the elongation and processability of the resin are further improved. If the weight-average molecular weight is 100,000 or lower, it is easier to prevent the viscosity of the adhesive solution from becoming excessively high, and it is less likely to produce appearance defects. Furthermore, by controlling the weight-average molecular weight to 40,000 to 70,000, it is easier to balance the elongation of the resin with the viscosity of the adhesive solution, and it can be used more preferably.

[0079] The hydroxyl value of the polyurethane resin (a) containing hydroxyl groups is preferably 0.5 mg KOH / g to 20 mg KOH / g, more preferably 3 mg KOH / g to 10 mg KOH / g. The hydroxyl groups are used in the crosslinking reaction with the polyisocyanate component (B) described later. By carrying out the crosslinking reaction, the adhesive is increased in molecular weight, thereby improving its heat resistance as a packaging material. The hydroxyl value can be determined, for example, according to the method in Japanese Industrial Standards (JIS) K 1557-1.

[0080] The glass transition temperature of the hydroxyl-containing polyurethane resin (a) is preferably -20°C to 40°C, more preferably -10°C to 20°C. If the glass transition temperature is above -20°C, the cohesive strength and adhesiveness of the resin are further improved. If the glass transition temperature is below 40°C, the affinity for the substrate during lamination is further improved, and the adhesive strength after aging is further improved.

[0081] The main agent (A) containing the polyurethane adhesive may simply contain the polyurethane resin (a) having hydroxyl groups, and may also contain the components described below as other components. Other components may be formulated into either the main agent (A) or the curing agent containing the polyisocyanate component (B), or may be added when formulating the main agent (A) and the curing agent containing the polyisocyanate component (B), more preferably formulated into the main agent (A).

[0082] (solvent)

[0083] To adjust the viscosity of the coating solution when applying the polyurethane adhesive to the substrate, the polyurethane adhesive may contain a solvent 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 dichloromethane, chlorobenzene, and chloroform; alcohols such as ethanol, isopropanol, and n-butanol; and water. These solvents may be used alone or in combination of two or more. Ethyl acetate is preferably used among these.

[0084] (Reaction Accelerator)

[0085] To promote the urethane esterification reaction, polyurethane adhesives may also contain reaction promoters. Examples of reaction promoters include metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimaleate; 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. One or more reaction promoters selected from this group may be used.

[0086] (Silane coupling agent)

[0087] To improve the bonding strength to metallic raw materials such as metal foil, polyurethane adhesives may also contain silane coupling agents. Examples of silane coupling agents include: vinyltrimethoxysilane, vinyltriethoxysilane, and other vinyl-containing trialkoxysilanes; 3-aminopropyltriethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane, and other amino-containing trialkoxysilanes; 3-glycidoxypropyltrimethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, and other glycidoxypropyltrialkoxysilanes.

[0088] The content of the silane coupling agent is preferably 0.1 to 5 parts by weight, more preferably 0.5 to 3 parts by weight, relative to 100 parts by weight of the solid component of the hydroxyl-containing polyurethane resin (a). Adding a silane coupling agent within this range can further improve the adhesion strength to the metal foil.

[0089] (Epoxy resin)

[0090] To improve the bonding strength to metallic raw materials such as metal foil, epoxy resin can be added to polyurethane adhesives. In particular, when epoxy resin is added to polyurethane resin (a) containing a polyester backbone, it reacts with the acid generated by hydrolysis under humid heat, thereby further improving the resistance to humid heat.

[0091] The epoxy resin is not limited to the following, but may include, for example: bisphenol A type epoxy resin, bisphenol F type epoxy resin, phenolic varnish type epoxy resin, cresol phenolic varnish type epoxy resin, 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.

[0092] In particular, from the viewpoint of adhesion and resistance to damp heat, an epoxy resin with a weight average molecular weight of 400 to 10,000 is preferred. From the viewpoint of adhesion and resistance to damp heat, the amount of epoxy resin mixed with 100 parts by weight of hydroxyl-containing polyurethane resin (a) is preferably 5 to 50 parts by weight, more preferably 10 to 20 parts by weight. By setting it to 5 parts by weight or more, the resistance to damp heat can be improved more effectively; by setting it to 50 parts by weight or less, the hardness of the adhesive layer can be moderately softened, making it easier to exhibit sufficient adhesion.

[0093] (Phosphoric acid or its derivatives)

[0094] To improve the bonding strength to metallic raw materials such as metal foil, polyurethane adhesives may contain phosphoric acid or phosphoric acid derivatives. As phosphoric acid, it only needs to have at least one free oxyacid, such as hypophosphoric acid, phosphorous acid, orthophosphoric acid, hypophosphoric acid, etc.; and condensed phosphoric acid such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, ultraphosphoric acid, etc. Furthermore, as derivatives of phosphoric acid, examples include derivatives obtained by partially esterifying the phosphoric acid with an alcohol while retaining at least one free oxyacid. Examples of such alcohols include aliphatic alcohols such as methanol, ethanol, ethylene glycol, and glycerol; and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglucinol. Phosphoric acid or its derivatives may be used alone or in combination of two or more. The amount of phosphoric acid or its derivative added is preferably 0.01 to 10 parts by weight relative to 100 parts by weight of the polyurethane resin (a) having hydroxyl groups, more preferably 0.05 to 5 parts by weight, and even more preferably 0.05 to 1 part by weight.

[0095] To improve the laminated appearance of packaging materials, polyurethane adhesives may also contain leveling agents or defoamers. 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, methacrylic copolymers, polyether-modified polymethylalkylsiloxane, alkyl acrylate copolymers, alkyl methacrylate copolymers, lecithin, etc.

[0096] Examples of defoamers include silicone resins, silicone solutions, copolymers of alkyl vinyl ethers with alkyl acrylates and alkyl methacrylates.

[0097] Polyurethane adhesives may also contain additives other than those described herein, to the extent that they do not impair the effects of this disclosure. Examples of additives include, for instance: 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; anti-blocking agents; colorants; fillers; crystal nucleating agents; and catalysts used to modulate the hardening reaction.

[0098] The main agent (A) is required to maintain its storage stability in a solution formulated with the additive in a hydroxyl-containing polyurethane resin (a) without causing turbidity or viscosity changes at low or high temperatures. Turbidity at incompatible sites can sometimes become the starting point for cracks during molding. Furthermore, changes in viscosity can sometimes make it difficult to adjust the coating process.

[0099] <Polyisocyanate component (B)>

[0100] The polyisocyanate component (B) undergoes a cross-linking reaction with the hydroxyl groups in the polyurethane resin (a) containing hydroxyl groups, thereby increasing the molecular weight of the adhesive layer and enhancing its internal cohesiveness, which exhibits energy elasticity. Furthermore, the isocyanate groups can react with water to form highly cohesive urea bonds, thus improving the cohesiveness of the adhesive layer through a self-cross-linking reaction during curing. Typically, the urethane or urea bonds formed through cross-linking reactions have hydrogen bonds and high polarity, resulting in poor compatibility with the resin and sometimes leading to poor appearance or defects during molding and processing. In this invention, by combining the polyurethane resin (a) containing the hydroxyl groups specified in this application with the polyisocyanate component (B), an adhesive layer with excellent compatibility, good appearance, and strong toughness can be formed, resulting in excellent physical properties as packaging material for energy storage components.

[0101] Furthermore, the polyisocyanate component (B) enhances the interaction with the substrate surface, as described later. Particularly when using substrates that have undergone physical treatments such as corona discharge or chemical treatments such as acid modification, the reactive functional groups in the polyisocyanate component (B) react chemically with the hydroxyl groups on the substrate surface, resulting in a strong interaction between the outer adhesive layer and the substrate. As described above, by using the polyisocyanate component (B), a strong outer adhesive layer can be formed, which suppresses the expansion and contraction of the substrate in response to rapid environmental changes, thus maintaining a high level of adhesive strength.

[0102] As the polyisocyanate component (B), the compounds listed in the (polyisocyanate) item constituting the polyurethane resin (a) having hydroxyl groups described above may be used, either alone or in combination with two or more.

[0103] In particular, the polyisocyanate component (B) is preferably a ureate form of diisocyanate, an adduct of diisocyanate with trimethylolpropane added, a biuret type, a prepolymer having isocyanate residues (an oligomer obtained from diisocyanate and polyol), a uretdione form having isocyanate residues, a ureocarbamate form, or a complex thereof. From the viewpoint of achieving excellent heat resistance, high cohesiveness, and high processability in electronic component applications, aromatic isocyanates or their derivatives are preferred.

[0104] Furthermore, if the polyisocyanate constituting the polyurethane resin (a) having hydroxyl groups is the same as the polyisocyanate component (B), the compatibility is further improved, and therefore this is preferred. That is, as the polyisocyanate component (B), it is more preferably an adduct containing toluene diisocyanate or an adduct in which trimethylolpropane is added to toluene diisocyanate.

[0105] Based on the mass of the solid component of the hydroxyl-containing polyurethane resin (a), the content of the polyisocyanate component (B) is preferably 10% to 40% by mass, more preferably 20% to 30% by mass. If the polyisocyanate component (B) is 10% by mass or more, the molecular weight of the adhesive layer can be effectively increased. This improves internal cohesion and makes it easier to obtain high adhesive strength. If it is 40% by mass or less, the amount of highly polar urethane or urea bonds generated through the crosslinking reaction can be appropriately controlled, and defects arising from appearance deterioration or processing-related deformation can be easily suppressed.

[0106] <Manufacturing of Packaging Materials for Energy Storage Components>

[0107] The method for manufacturing the packaging material for the energy storage element disclosed herein can be used in various ways without particular limitation. For example, the outer-side resin film layer (1) and the metal foil layer (3) can be laminated using a polyurethane adhesive that forms the outer-side adhesive layer (2) to obtain an intermediate laminate comprising an outer-side resin film layer (1) / outer-side adhesive layer (2) / metal foil layer (3), and then a heat-sealing layer (5) can be laminated on the surface of the metal foil layer (3) of the intermediate laminate using an inner-side adhesive (hereinafter referred to as manufacturing method 1). Alternatively, the metal foil layer (3) and the heat-sealing layer (5) can be laminated using an inner-side adhesive to obtain an intermediate laminate comprising a metal foil layer (3) / inner-side adhesive layer (4) / heat-sealing layer (5), and then the metal foil layer (3) of the intermediate laminate can be laminated with the outer-side resin film layer (1) using the polyurethane adhesive (hereinafter referred to as manufacturing method 2).

[0108] In manufacturing method 1, it is preferable to coat the polyurethane adhesive onto one side of either the outer resin film layer (1) or the metal foil layer (3), allow the solvent to evaporate, and then, under heat and pressure, overlap the other substrate onto the uncured outer adhesive layer. The outer adhesive layer is then aged at room temperature (e.g., 25°C) to less than 100°C to harden it. If the aging temperature is less than 100°C, thermal shrinkage of the outer resin film layer (1) will not occur, thus easily preventing a decrease in elongation at break or stress at break that could affect molding, or a decrease in molding productivity due to film curling. The coating amount of the dried outer adhesive is preferably 1 g / m². 2 ~15g / m 2 about.

[0109] Furthermore, in the packaging material for energy storage components disclosed herein, even when the adhesive is a thin film, the adhesive strength and formability after high temperature and high humidity / long-term durability tests are excellent, and no appearance defects such as interlayer lifting occur. Specifically, in the packaging material for energy storage components disclosed herein, even when the adhesive coating amount after drying is 3 g / m², 2 The coating amount is further reduced to 2 g / m². 2 The adhesive exhibits excellent bonding strength, formability, and interlayer lift suppression after high temperature and humidity / long-term durability tests, demonstrating a superior performance that balances the adhesive's thin-film formation and formability with the interlayer bonding strength after high temperature and humidity / long-term durability tests.

[0110] Similarly, in the case of manufacturing method 2, the polyurethane adhesive can be applied to either the outer resin film layer (1) or the metal foil layer (3) of the intermediate laminate.

[0111] Methods for forming the outer side adhesive layer include using a corner-cutting roller coating machine, a dry laminator, a roller coating machine, a die coating machine, a roller coating machine, a bar coating machine, a gravure roller coating machine, a reverse roller coating machine, a scraper coating machine, a gravure coating machine, and a micro gravure coating machine.

[0112] <Outer layer resin film (1)>

[0113] The outer resin film layer (1) is not particularly limited, but it is preferable to use an extended film containing polyamide or polyester. Alternatively, it can be colored using pigments such as carbon black or titanium dioxide. Furthermore, the non-laminated surface of the outer resin film layer (1) can be coated with a coating agent or slip agent for the purpose of preventing damage or improving electrolyte resistance, or it can be coated with printing ink for design purposes. Additionally, the outer resin film layer (1) can be pre-laminated with two or more layers. The thickness of the outer resin film layer (1) is not particularly limited, but is preferably 12 μm to 100 μm.

[0114] <Metal foil layer (3)>

[0115] The metal foil layer (3) is not particularly limited, but an aluminum foil layer is preferred. The thickness of the metal foil layer (3) is not particularly limited, but is preferably 20 μm to 80 μm. In addition, it is preferable to perform anti-corrosion treatment on the surface of the metal foil layer (3) by means of chromate phosphate treatment, chromate chromate treatment, chromium oxide treatment, zinc phosphate treatment, zirconium phosphate treatment, zirconium oxide treatment, titanium phosphate treatment, hydrofluoric acid treatment, cerium treatment, hydrotalcite treatment, etc. By performing anti-corrosion treatment, corrosion and deterioration of the metal foil surface caused by the battery electrolyte can be suppressed. Furthermore, it is preferable to sinter an organic primer such as phenolic resin, amide resin, acrylic resin, polyvinyl alcohol, coupling agent, etc., onto the anti-corrosion treated surface at a high temperature of about 200°C. By performing organic primer treatment, the metal foil and the adhesive can be bonded more firmly, further suppressing the lifting between the metal foil and the adhesive.

[0116] <Heat-sealed layer (5)>

[0117] The heat-sealing layer (5) is not particularly limited, but is preferably an unstretched film comprising at least one thermoplastic resin selected from the group consisting of polyethylene, polypropylene, olefin copolymers, their acid-modified derivatives and ionomers. The thickness of the heat-sealing layer is not particularly limited, but is preferably 20 μm to 150 μm.

[0118] <Inner side adhesive layer (4)>

[0119] There are no particular limitations on the adhesive used to form the inner side adhesive layer (4). An adhesive whose bonding strength between the metal foil layer (3) and the heat-sealing layer (5) will not be reduced by the electrolyte of the energy storage element can be used. The inner side adhesive layer (4) can be formed, for example, by coating the metal foil layer (3) with an adhesive composed of polyolefin resin and polyisocyanate or a polyol and polyisocyanate using a gravure coating machine or the like and drying the solvent, then overlapping the heat-sealing layer (5) onto the adhesive layer under heating and pressure, and then aging it at room temperature or under heating. 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 then the heat-sealing layer (5) can be overlapped on the adhesive layer to bond the metal foil layer (3) together, thereby forming the inner side adhesive layer (4). If both the outer side adhesive layer (2) and the inner side adhesive layer (4) need to be aged, they can also be aged together after obtaining a laminate containing an outer side resin film layer (1), an uncured outer side adhesive layer, a metal foil layer (3), an uncured inner side adhesive layer and a heat-sealing layer (5) stacked sequentially from the outside.

[0120] <Containers for Energy Storage Components>

[0121] The container for the energy storage element disclosed herein can be obtained by molding the packaging material for the energy storage element of the present disclosure in such a way that the outer resin film layer (1) forms a convex surface and the heat-sealing layer (5) forms a concave surface. Furthermore, the term "concave surface" in this disclosure refers to the surface formed by molding the flat packaging material for the energy storage element. Figure 2 In the case of the tray shape shown, there is a recessed surface that can accommodate electrolyte inside. The term "convex surface" in this disclosure refers to the back side of the surface having the recessed surface.

[0122] <Electric Storage Components>

[0123] The energy storage element disclosed herein is made using the aforementioned energy storage element container, such as secondary batteries like lithium-ion batteries, nickel-metal hydride batteries, and lead-acid batteries, as well as electrochemical capacitors like double-layer capacitors. A typical energy storage element includes: a battery component containing electrodes, leads extending from the electrodes, and a container for housing. In the energy storage element of this disclosure, the energy storage element container is used for housing. The housing is formed from energy storage element packaging material with a heat-sealed layer (5) as the inner side. The heat-sealed layers (5) of two packaging materials can be overlapped facing each other, and the periphery of the overlapping packaging materials can be heat-fused together. Alternatively, one packaging material can be folded back and overlapped, and the periphery of the packaging material can be heat-fused together in the same way.

[0124] [Example]

[0125] The present disclosure will be further illustrated below with examples and comparative examples. Unless otherwise specified, “parts” and “%” in the examples and comparative examples refer to “parts by mass” and “% by mass”.

[0126] <Determination of acid value (AV)>

[0127] Accurately measure approximately 1 g of the sample (polyester polyol solution) into a co-stoppered Erlenmeyer flask, add 100 ml of a toluene / ethanol mixture (volume ratio: toluene / ethanol = 2 / 1) and dissolve. Add phenolphthalein indicator and maintain for 30 seconds. Then, titrate with 0.1 N alcoholic potassium hydroxide solution until the solution turns pale pink. Calculate the acid value (mg KOH / g) using the following formula.

[0128] Acid value (mgKOH / g) = (5.611 × a × F) / S

[0129] Where S: the amount of sample taken (g)

[0130] a: Volume (ml) of 0.1N alcoholic potassium hydroxide solution consumed.

[0131] F: Titration of 0.1N alcoholic potassium hydroxide solution

[0132] <Determination of hydroxyl value (OHV)>

[0133] Accurately measure approximately 1 g of the sample (polyester polyol or hydroxyl-containing urethane resin (a), etc.) into a co-stoppered Erlenmeyer flask, add 100 ml of a toluene / ethanol mixture (volume ratio: toluene / ethanol = 2 / 1) and dissolve. Then, accurately add 5 ml of an acetylation agent (using pyridine to dissolve 25 g of acetic anhydride in a 100 ml solution) and stir for approximately 1 hour. Add phenolphthalein indicator and continue for 30 seconds. Afterward, titrate with 0.5 N alcoholic potassium hydroxide solution until the solution turns pale pink, and calculate the hydroxyl value (mg KOH / g) according to the following formula.

[0134] Hydroxyl value (mgKOH / g) = [{(ba)×F×28.05} / S] + D

[0135] Where S: the amount of sample taken (g)

[0136] a: Volume (ml) of 0.5N alcoholic potassium hydroxide solution consumed.

[0137] b: Volume (ml) of 0.5N alcoholic potassium hydroxide solution consumed in the blank experiment.

[0138] F: Titration of 0.5N alcoholic potassium hydroxide solution

[0139] D: Acid value (mgKOH / g)

[0140] <Determination of number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn)>

[0141] Average molecular weight and molecular weight distribution were calculated using the equivalent values ​​of standard polystyrene as determined in the following manner: using Shodex (registered trademark) (manufactured by Showa Denko), columns: KF-805L, KF-803L, and KF-802 (all trade names, manufactured by Showa Denko), the column temperature was set to 40°C, tetrahydrofuran (THF) was used as the eluent, the flow rate was set to 0.2 ml / min, the detection was set to infrared (RI) detection, and the sample concentration was set to 0.02% by mass.

[0142] <Glass transition temperature (Tg)>

[0143] The glass transition temperature was determined using a differential scanning calorimeter (DSC). Specifically, approximately 2 mg of the target compound was weighed onto an aluminum pan, which was then placed on the DSC measuring stand. The endothermic peak value of the graph obtained under a heating rate of 5 °C / min was read, and this peak temperature was taken as the glass transition temperature.

[0144] Synthesis of Polyester Polyols

[0145] (Polyester 1)

[0146] An esterification reaction was carried out at 170℃–230℃ for 10 hours using 148 parts isophthalic acid, 296 parts terephthalic acid, 260 parts adipic acid, 250 parts ethylene glycol, and 46 parts neopentyl glycol. After distilling off a predetermined amount of water, 0.05 parts tetraisobutyl titanate were added, and the mixture was slowly subjected to reduced pressure and transesterification at 1.3 hPa–2.6 hPa and 230℃–250℃ for 3 hours. Polyester 1, a polyester polyol, was obtained with a yield of 83.9% and a number average molecular weight (Mn) of 9,200, a weight average molecular weight (Mw) of 19,000, a molecular weight distribution (Mw / Mn) of 2.07, a hydroxyl value of 14.0 mg KOH / g, an acid value of 0.2 mg KOH / g, and a glass transition temperature of 2℃. The ester bond concentration of polyester 1 was 10.63 mmol / g. If we assume that the excess hydroxyl components are removed by distillation in roughly equal amounts, and set the total of the carboxylic acid components and hydroxyl components at 200 mol%, then the composition of the obtained polyester 1 is isophthalic acid: terephthalic acid: adipic acid: ethylene glycol: neopentyl glycol = 20:40:40:90:10 (mol%).

[0147] (Polyester 2 to Polyester 13)

[0148] To obtain polyester 2 to polyester 13, the carboxylic acid component and the hydroxyl component are reacted in the same manner as polyester 1, so that the amount of carboxylic acid component and the hydroxyl component in the obtained polyester polyol are in the proportion shown in Table 1.

[0149] [Table 1]

[0150]

[0151] The abbreviations in Table 1 are shown below.

[0152] PA: Phthalic anhydride

[0153] IPA: isophthalic acid

[0154] TPA: terephthalic acid

[0155] AdA: Adipic acid

[0156] EG: Ethylene glycol

[0157] NPG: Neopentyl glycol

[0158] 1,6-HD: 1,6-hexanediol

[0159] MPO: 2-methyl-1,3-propanediol

[0160] DEG: Diethylene glycol

[0161] <Synthesis of hydroxyl-containing polyurethane resin (a)>

[0162] (carbamate(a)-1)

[0163] The obtained polyester 1,100 parts and ethyl acetate 40 parts were placed in a 1-liter four-necked flask, heated to 80°C, and stirred until the solution became homogeneous. Toluene diisocyanate 2.0 parts and dibutyltin dilaurate 0.15 parts were added, and the reaction was carried out for 4 hours. After the reaction was completed, ethyl acetate 113 parts were added to obtain a urethane (a)-1 solution as a hydroxyl-containing polyurethane resin, with an ester bond concentration of 10.42 mmol / g, a urethane bond concentration of 0.23 mmol / g, Mn of 23,500, Mw of 56,100, Tg of 4°C, a hydroxyl value of 7.9 mg KOH / g, and a non-volatile content of 40%.

[0164] (Carbamate(a)-2~Carbamate(a)-15, Comparison(a)-1~Comparison(a)-4)

[0165] Except for changing the formulation to the amount shown in Table 2, the polyol was reacted with the polyisocyanate in the same manner as urethane (a)-1 to obtain urethane (a)-2 to urethane (a)-15, and comparative (a)-1 to comparative (a)-4 as hydroxyl-containing polyurethane resins (a).

[0166] [Table 2]

[0167]

[0168] The abbreviations in Table 2 are shown below.

[0169] NPG: Neopentyl Glycol

[0170] TDI: Tolylene diisocyanate (Coronate T-80 (trade name), manufactured by Tosoh Corporation, NCO content 48.2%)

[0171] MDI: 4,4'-diphenylmethane diisocyanate (MILLIONATE MT, manufactured by Tosoh Corporation, NCO content 33.5%)

[0172] HDI: Hexamethylene diisocyanate (Desmodur H, a registered trademark, manufactured by Covestro, with an NCO content of 49.9%)

[0173] IPDI: Isophorone diisocyanate (Desmodur I (trade name), manufactured by Covestro, NCO content 37.7%)

[0174] H6XDI: 1,3-bis(isocyanomethyl)cyclohexane (Takenate 600 (trade name) manufactured by Mitsui Chemicals Co., Ltd., NCO content 43.2%)

[0175] <Manufacturing of Packaging Materials for Energy Storage Components>

[0176] [Example 1]

[0177] 250 parts (100 parts in solids equivalent) of urethane (a)-1 solution and 1.0 part of glycidyloxypropyltrimethoxysilane as an additive were added and stirred for 30 minutes. The mixture was then diluted with ethyl acetate to obtain a main agent (A) with a solid content concentration of 40%. 40 parts (30 parts in solids equivalent) of coronate L (trade name, manufactured by Tosoh Corporation, solid content concentration of 75%, NCO content of 13.2%) as polyisocyanate component (B) were added and diluted with ethyl acetate to prepare an adhesive solution with a solid content concentration of 30%. The adhesive solution was coated on one side of an aluminum foil with a thickness of 40 μm as an outer side adhesive layer (2) using a dry laminator. After the solvent evaporated, an extended polyamide film with a thickness of 30 μm was laminated to obtain an intermediate laminate. The coating amount of the adhesive after drying was set to 2 g / m. 2 and 4g / m 2 Subsequently, using a dry laminator, the adhesive for the inner layer adhesive layer (described later) is coated onto the other side of the aluminum foil of the obtained intermediate laminate. After the solvent evaporates, a 30 μm thick unstretched polypropylene film is laminated to obtain the laminate. The coating amount of the adhesive after drying is set to 4 g / m². 2 Subsequently, the adhesive layers on the outer and inner sides were aged for 7 days at 60°C and 30% RH (relative humidity) and 60°C and 90% RH respectively, so that the adhesive layers on the outer and inner sides were hardened, and a battery packaging material with a structure including an outer resin film layer (1) / an outer adhesive layer (2) / a metal foil layer (3) / an inner adhesive layer (4) / a heat-sealing layer (5) was obtained.

[0178] (Adhesive for the inner side adhesive layer)

[0179] AD-502 (trade name, manufactured by Toyo Morton, a polyester polyol) was used as the main agent, and CAT-10L (trade name, manufactured by Toyo Morton, an isocyanate-based curing agent) was used as the curing agent. The mixture was formulated with a main agent / curing agent ratio of 100 / 10 (mass ratio), and the solid content was adjusted to 30% using ethyl acetate. The resulting substance was used as an adhesive for the inner side adhesive layer.

[0180] [Examples 2 to 17, Comparative Examples 1 to 5]

[0181] Except for changing the mixing quantity (parts) to Table 3, perform the same operation as in Example 1 to obtain battery packaging material.

[0182] <Evaluation of Packaging Materials for Energy Storage Components>

[0183] The obtained packaging materials for energy storage components were evaluated as follows. The results are shown in Table 3.

[0184] [Evaluation of the storage stability of main agent A]

[0185] The main agent (A) with a solid content of 40% was stored at 5°C for 4 weeks, then allowed to stand at 23°C for 4 hours. The changes in appearance and viscosity were then evaluated using the following criteria. Viscosity was measured using a type B viscometer at 25°C.

[0186] A: No changes in appearance or viscosity were observed before and after storage at 5°C (good).

[0187] B: The product appeared cloudy before and after storage at 5°C, but returned to its original appearance after heating at 60°C for 2 hours. The viscosity increase was less than 20% (making it usable).

[0188] C: The product becomes cloudy before and after storage at 5°C, and does not return to its original state even after heating at 60°C for 2 hours. Alternatively, the viscosity increases by more than 20% before and after storage at 5°C (making it unusable).

[0189] [Appearance Evaluation of Packaging Materials]

[0190] The coating amount of the outer side adhesive after drying is 4 g / m². 2 Battery packaging materials were visually inspected and evaluated according to the following criteria under aging conditions of 60°C, 30%RH, 7 days and 60°C, 90%RH, 7 days.

[0191] A: No whitening or foaming was observed (good).

[0192] B: There is some whitening, but no foaming was observed (it is usable).

[0193] C: Whitening or bubbling was observed (unusable).

[0194] [Laminated strength (before damp heat test)]

[0195] The amount of the outer side adhesive applied after drying is 2g / m². 2 and 4g / m 2 The battery packaging material, aged at 60℃, 30%RH, and for 7 days, was cut into 200mm × 15mm pieces. A T-peel test was performed using a tensile testing machine to determine the peel strength (N / 15mm width) between the extended polyamide film and aluminum foil. The test was conducted at 20℃ and 65%RH with a load speed of 300mm / min. The results were evaluated based on the average of five test pieces according to the following criteria.

[0196] S: The average peel strength is above 7N (very good).

[0197] A: The average peel strength is above 4N but less than 7N (good).

[0198] B: The average peel strength is above 2N but less than 4N (suitable for use).

[0199] C: The average peel strength is less than 2N (unusable).

[0200] [Laminate strength (after damp heat test)]

[0201] The amount of the outer side adhesive applied after drying is 2g / m². 2 and 4g / m 2 The battery packaging materials were placed in constant temperature and humidity baths at 85°C and 85%RH for 7 days under aging conditions of 60°C and 30%RH. After standing for 168 hours, they were removed from the constant temperature and humidity baths and placed in a constant temperature and humidity bath at 20°C and 65%RH for 2 hours. The same operation as before the damp heat test was performed, and the lamination strength was evaluated according to the same standard.

[0202] [Moldability Evaluation]

[0203] The amount of the outer side adhesive applied after drying is 2g / m². 2 The battery packaging material, aged at 60°C and 30% RH for 7 days, was cut into 80mm x 80mm pieces to form blanks. For the blanks, a single-stage forming process was performed using a straight die with no limit on forming height, with the polyamide film extended to the outside. Formability was evaluated based on the maximum forming height without foil breakage or interlayer lifting, according to the following criteria: The die punch shape was a square with one side of 30mm, a corner radius of 2mm, and a punch shoulder radius of 1mm. The die cavity shape was a square with one side of 34mm, a die cavity corner radius of 2mm, and a die cavity shoulder radius of 1mm. The clearance between the punch and the die cavity was 2mm on one side, resulting in an inclination corresponding to the forming height.

[0204] S: Maximum molding height is 6mm or more (very good).

[0205] A: Maximum molding height is 4mm or more but less than 6mm (good).

[0206] B: Maximum molding height is 2mm or more but less than 4mm (can be used).

[0207] C: Maximum molding height is less than 2mm (cannot be used).

[0208] [Resistance to damp heat of molded products]

[0209] The amount of the outer side adhesive applied after drying is 2g / m². 2 The battery packaging material, aged at 60℃, 30%RH for 7 days, was cut into 80mm×80mm pieces to form blanks. For the blanks, a straight die with no limit on forming height was used to stretch the polyamide film to the outside, achieving a single-stage forming with a forming height of 3mm to obtain a molded part. The molded part was then placed in a constant temperature and humidity bath at 85℃ and 85%RH for 168 hours. After standing, it was removed from the bath, visually inspected for any floating, and evaluated according to the following criteria: The punch shape of the die used was a square with one side of 30mm, a corner radius of 2mm, and a punch shoulder radius of 1mm. The die cavity shape of the die used was a square with one side of 34mm, a die cavity corner radius of 2mm, and a die cavity shoulder radius of 1mm.

[0210] A: No buoyancy was observed (good).

[0211] B: One of the four sides will float up (can be used).

[0212] C: Floating occurs on two or more of the four sides (unusable).

[0213] [Heat resistance of the molded product]

[0214] Except for changing the standing conditions from 85°C, 85%RH for 168 hours to 120°C, 168 hours, similar to the evaluation of the moisture and heat resistance of the molded product, visually confirm whether floating occurs, and evaluate according to the following criteria.

[0215] A: No buoyancy was observed (good).

[0216] B: One of the four sides will float up (can be used).

[0217] C: Floating occurs on two or more of the four sides (unusable).

[0218] [Table 3]

[0219]

[0220] The abbreviations in Table 3 are shown below.

[0221] SC-1: Glycidoxypropyltrimethoxysilane

[0222] EP-1: Bisphenol A type epoxy resin (trade name: JER834, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of 250, molecular weight of approximately 470)

[0223] EP-2: Bisphenol A type epoxy resin (trade name: JER1002, manufactured by Mitsubishi Chemical Corporation, epoxy equivalent of 650, molecular weight of approximately 1,200)

[0224] DBTDL: Dibutyltin dilaurate

[0225] NCO-1: Trimethylolpropane adduct of toluene diisocyanate (trade name: Coronate L, manufactured by Tosoh Corporation, non-volatile component concentration 75%, NCO content 13.2%)

[0226] As shown in Table 3, the main agent used in packaging materials containing hydroxyl-containing polyurethane resin (a) with a predetermined ester bond concentration, as the main agent for forming the outer side adhesive layer, exhibits good storage stability and high adhesion and moldability. In particular, even when the coating amount of the outer side adhesive layer is 2 g / m², the results demonstrate this. 2 The film exhibits excellent lamination strength and formability in packaging materials. Furthermore, if the urethane bond concentration is within a predetermined range, it demonstrates excellent compatibility with the polyisocyanate used as a curing agent, suppressing appearance defects such as foaming or cloudiness even under high humidity conditions of 60°C and 90% RH. In particular, in Example 10, the polyurethane resin (a) with hydroxyl groups exhibits excellent storage stability, lamination strength of the outer side adhesive layer, and processability due to the appropriate ester bond concentration, urethane bond concentration, weight average molecular weight, and glass transition temperature.

[0227] On the other hand, Comparative Example 1, corresponding to the embodiment in International Publication No. 2018 / 117080, has a low ester bond concentration and low storage stability as the main agent, making it difficult to coat and reducing lamination strength. Comparative Example 2, corresponding to the embodiment in Japanese Patent Application Publication No. 2016-196580, has a low ester bond concentration and insufficient cohesion, with a coating weight of 2 g / m². 2 Poor formability occurs when making thin films.

[0228] Comparative Examples 3 and 4 are examples of polyurethane resin (a) with low ester bond concentration containing hydroxyl groups, which resulted in poor appearance when cured under high humidity conditions of 60°C and 90% RH. Due to this effect, the lamination strength or moldability decreased after the damp heat test.

[0229] Comparative Example 5 is an example of a resin in which an unurethane-treated polyester polyol is used as the main agent. Its compatibility with the polyisocyanate component (B) is reduced, resulting in poor appearance or reduced lamination strength when cured under high humidity conditions of 60°C and 90% RH.

Claims

1. A packaging material for an energy storage element, comprising, from the outside, at least sequentially stacked an outer resin film layer, an outer adhesive layer, a metal foil layer, an inner adhesive layer, and a heat-sealing layer, wherein the packaging material for the energy storage element, The outer side adhesive layer is formed of a polyurethane adhesive containing a main agent (A) and a hardener, wherein the main agent (A) comprises a polyurethane resin (a) having hydroxyl groups, and the hardener comprises a polyisocyanate component (B). The hydroxyl-containing polyurethane resin (a) is a reaction product of polyester polyol and polyisocyanate, and the ester bond concentration is 9.20 mmol / g to 10.50 mmol / g. The ester bond concentration of the hydroxyl-containing polyurethane resin (a) is calculated using the following formula. Calculation formula: Polyester bond concentration (mmol / g) = Polyester bond concentration of polyester polyol × Ratio of polyester polyol to the total mass of polyol and polyisocyanate constituting urethane resin (mass%) in, The ester bond concentration of the polyester polyol is calculated using the following formula. Formula: Polyester bond concentration (mmol / g) = (mol of carboxylic acid component × total number of functional groups of carboxylic acid) / (total amount of component × solid yield) × 1000.

2. The packaging material for energy storage components according to claim 1, wherein... The urethane bond concentration of the hydroxyl-containing polyurethane resin (a) is 0.10 mmol / g to 0.90 mmol / g. The concentration of the carbamate bonds is calculated using the following formula 1. Formula 1: Carbamate bond concentration (mmol / g) = [(NCO content of polyisocyanate (mass%) ÷ 100) × (the blending ratio of polyisocyanate (mass%) to the total (mass%) of polyols and polyisocyanates constituting the carbamate resin) ÷ 42 × 1000] + [(number of carbamate bonds inside the polyisocyanate ÷ molecular weight of polyisocyanate) × (the blending ratio of polyisocyanate (mass%) to the total (mass%) of polyols and polyisocyanates constituting the carbamate resin) × 1000].

3. The packaging material for energy storage components according to claim 1 or 2, wherein... The hydroxyl value of the polyurethane resin (a) having hydroxyl groups is 0.5 mgKOH / g to 20 mgKOH / g.

4. The packaging material for energy storage components according to claim 1 or 2, wherein... The hydroxyl-containing polyurethane resin (a) is a product of the reaction of a polyester polyol with a weight average molecular weight of 5,000 to 30,000 and a polyisocyanate.

5. The packaging material for energy storage components according to claim 1 or 2, wherein... The weight-average molecular weight of the hydroxyl-containing polyurethane resin (a) is 40,000 to 70,000.

6. The packaging material for energy storage components according to claim 1 or 2, wherein... The glass transition temperature of the hydroxyl-containing polyurethane resin (a) is -10℃ to 20℃.

7. A container for an energy storage element, formed from packaging material for an energy storage element as described in any one of claims 1 to 6, wherein the outer resin film layer (1) of the container for the energy storage element forms a convex surface and the heat-sealing layer (5) forms a concave surface.

8. An energy storage element, comprising the energy storage element container as described in claim 7.

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