CN115498342A

CN115498342A - Packaging material for electricity storage element, container for electricity storage element, and electricity storage element

Info

Publication number: CN115498342A
Application number: CN202110680353.0A
Authority: CN
Inventors: 广嶋努; 小清水渉; 花木寛
Original assignee: Toyo Morton Ltd; Toyo Ink SC Holdings Co Ltd
Current assignee: Toyo Morton Ltd; Artience Co Ltd
Priority date: 2021-06-18
Filing date: 2021-06-18
Publication date: 2022-12-20

Abstract

Provided are a packaging material for an electric storage element, a container for an electric storage element, and an electric storage element. The problem can be solved by a packaging material for an electric storage element, comprising: the heat-sealing sheet has 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-sealing layer are laminated in this order from the outside, the outer layer side adhesive layer is formed from a polyurethane adhesive containing a main agent and a curing agent, the main agent contains a polyurethane resin (A) having a hydroxyl group, the curing agent contains a polyisocyanate component (B), the polyisocyanate constituting the polyurethane resin (A) having a hydroxyl group contains toluene diisocyanate or an adduct in which trimethylolpropane is added to toluene diisocyanate, and the urethane bond concentration of the polyurethane resin (A) having a hydroxyl group is 0.10mmol/g or more and 0.40mmol/g or less.

Description

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

Technical Field

The present invention relates to a packaging material for an electric storage element used for forming a container for an electric storage element such as a lithium ion battery, and more particularly, to a packaging material for an electric storage element having good appearance and excellent adhesion strength and moldability, a container for an electric storage element using the packaging material, and an electric storage element.

Background

Due to rapid development of electronic devices such as mobile phones and portable personal computers, there is an increasing demand for power storage elements such as secondary batteries such as lithium ion batteries and nickel hydrogen batteries, and electrochemical capacitors such as electric double layer capacitors. Among these, small lithium ion batteries have attracted attention in terms of high energy density and light weight. As an outer package of a lithium ion battery, a metal can has been used, but from the viewpoint of weight reduction and productivity, a packaging material obtained by laminating a plastic film, a metal foil, or the like has become the mainstream.

Patent document 1 discloses a battery case packaging material having a structure in which a heat-resistant stretched resin layer, an adhesive layer, an aluminum layer, and a thermoplastic unstretched resin layer are laminated in this order, wherein the adhesive layer is formed from a cured product of an adhesive composition containing a polyester resin exhibiting a glass transition temperature of-20 to 45 ℃ and 10 to 70 parts by mass of a toluene diisocyanate-based curing agent per 100 parts by mass of the polyester resin.

Patent document 2 discloses a battery packaging material in which 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-sealing layer are laminated in this order, and the outer layer side adhesive layer is formed of an adhesive containing two types of polyester polyols having a specific glass transition temperature, a polyisocyanate, and a silane coupling agent.

Further, patent document 3 describes that an adhesive is used so that the coating weight after drying is 4g/m ² The adhesive comprises a polyol composition obtained by chain-extending a polyester polyol with a polyisocyanate and a polyisocyanate composition.

[ Prior art documents ]

[ patent document ]

[ patent document 1] Japanese patent laid-open publication No. 2013-149562

[ patent document 2] Japanese patent laid-open No. 2014-091770

[ patent document 3] International publication No. 2018/117080

Disclosure of Invention

[ problems to be solved by the invention ]

In recent years, as the use of electric storage devices in vehicles or homes has expanded to increase the capacity of secondary batteries, improvement in moldability has been increasingly demanded for packaging materials for electric storage devices. In addition, in the vehicle-mounted applications, weight reduction is also required, and even when the adhesive is formed into a film, the adhesive strength between layers of plastic films, metal foils, and the like of the packaging material is required to be maintained after molding and long-term durability testing, and further, no appearance abnormality is required.

However, the packaging materials described in

patent documents

1 and 2 use a urethane adhesive in which an excessive amount of an isocyanate component is blended in an adhesive layer, and therefore, a resin having a urea bond is generated by the reaction of an excessive amount of isocyanate groups with water, and the compatibility of the urea bond-containing resin with the urethane adhesive is poor, and there is a problem that the packaging material is poor in appearance and difficult to be deeply molded.

Further, the packaging material described in patent document 3 has a problem that it is difficult to combine the thinning of the adhesive agent and the moldability with the interlayer adhesion strength after the long-term durability test at high temperature and high humidity, because it does not use the polyurethane resin (a) having a specific structural component and urethane bond concentration.

Accordingly, an object of the present invention is to provide a packaging material for an electric storage element, which has excellent moldability without lowering the interlayer bonding strength after a long-term durability test at high temperature and high humidity even when the adhesive is a thin film and which does not cause appearance defects such as floating between layers, a container for an electric storage element using the packaging material, and an electric storage element having excellent reliability.

[ means for solving the problems ]

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

One embodiment of the present invention relates to a packaging material for an electric storage element, which has a structure in which at least 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 laminated in this order from the outside, and which has a structure in which the outer layer side resin film layer, the outer layer side adhesive layer, the metal foil layer (3), the inner layer side adhesive layer, and the heat seal layer (5) are laminated in this order

The outer layer side adhesive layer (2) is formed of a polyurethane adhesive containing a main agent containing a polyurethane resin (A) having a hydroxyl group and a hardener containing a polyisocyanate component (B),

the polyisocyanate constituting the polyurethane resin (A) having hydroxyl groups contains tolylene diisocyanate or an adduct of trimethylolpropane to tolylene diisocyanate,

the urethane bond concentration of the hydroxyl group-containing polyurethane resin (A) is 0.10mmol/g or more and 0.40mmol/g or less.

Another embodiment of the present invention relates to the packaging material for electricity storage elements, wherein the weight average molecular weight of the polyurethane resin (a) having a hydroxyl group is 50,000 to 250,000.

Still another embodiment of the present invention relates to the packaging material for an electric storage element, wherein a hydroxyl group value of the polyurethane resin (a) having a hydroxyl group is 0.5mgKOH/g to 35mgKOH/g.

Still another embodiment of the present invention relates to the electricity storage element packaging material, wherein the polyurethane resin (a) having a hydroxyl group is a reaction product of a polyester polyol having a weight average molecular weight of 10,000 to 30,000 and a polyisocyanate.

In another embodiment of the present invention, the container for an electric storage element is formed of the electric storage element packaging material, and the outer layer side resin film layer (1) forms a convex surface and the heat seal layer (5) forms a concave surface.

Still another embodiment of the present invention relates to an electric storage device including the capacitor for an electric storage device.

[ Effect of the invention ]

The present invention provides a packaging material for an electricity storage element, which has excellent moldability and does not cause appearance defects such as floating between layers, and which has excellent reliability, without lowering the interlayer bonding strength after a long-term durability test at high temperature and high humidity, even if the adhesive is a thin film, and a container for an electricity storage element using the packaging material.

Drawings

Fig. 1 is a schematic cross-sectional view of a power storage element packaging material of the present invention.

Fig. 2 is a schematic perspective view of one form (tray-like) of the energy storage element container according to the present invention.

[ description of symbols ]

(1): outer layer side resin film layer

(2): outer layer side adhesive layer

(3): metal foil layer

(4): inner layer side adhesive layer

(5): and (7) heat sealing the layers.

Detailed Description

< packaging Material for Electrical storage device >

The present invention will be described in detail below with reference to preferred embodiments.

As shown in fig. 1, a power storage element packaging material according to the present invention includes: the adhesive layer (2) is formed from a polyurethane adhesive containing a main agent and a curing agent, the main agent contains a polyurethane resin (A) having a hydroxyl group, the curing agent contains a polyisocyanate component (B), the polyisocyanate constituting the polyurethane resin (A) having a hydroxyl group contains toluene diisocyanate or an adduct of toluene diisocyanate with trimethylolpropane, and the polyurethane resin (A) having a hydroxyl group has a urethane bond concentration of 0.10mmol/g to 0.40mmol/g.

< outer layer side adhesive layer (2) >

The outer layer side adhesive layer (2) of the present invention is formed of a polyurethane adhesive containing a main agent containing a polyurethane resin (A) having a hydroxyl group and a hardener containing a polyisocyanate component (B).

The main agent is first explained. The main agent contains a hydroxyl group-containing polyurethane resin (a) described later and various additives.

< polyurethane resin (A) having hydroxyl group >

The polyurethane resin (a) having a hydroxyl group is characterized in that:

< 1 > the polyisocyanate constituting the polyurethane resin (A) having hydroxyl groups contains tolylene diisocyanate or an adduct of trimethylolpropane to tolylene diisocyanate,

< 2 > the urethane bond concentration of the polyurethane resin (A) having a hydroxyl group is 0.10mmol/g or more and 0.40mmol/g or less,

and can be obtained by subjecting hydroxyl groups in a polyol described later and isocyanate groups in a polyisocyanate to a urethanization reaction under conditions in which the hydroxyl groups are excessive.

The main agent of the polyurethane adhesive may contain other resins as long as it contains the hydroxyl group-containing polyurethane resin (a).

In the present invention, it is important to control the urethane bond concentration of the polyurethane resin (a) having a hydroxyl group constituting the outer layer side adhesive layer, and by setting the urethane bond concentration within a predetermined range, the compatibility with the polyisocyanate component (B) as a curing agent can be improved, and an adhesive layer having a high crosslinking density and excellent durability and appearance can be formed.

As described above, the urethane bond concentration of the polyurethane resin (A) having a hydroxyl group is 0.10mmol/g to 0.40mmol/g. When the content is 0.10mmol/g or more, an excellent effect of improving compatibility is obtained, and appearance and adhesion are improved. When the concentration is 0.40mmol/g or less, the urethane bond concentration is not excessive and the viscosity is appropriate, and thus the coating property and the appearance are excellent. From the same viewpoint, the urethane bond concentration of the polyurethane resin (a) having a hydroxyl group is preferably 0.15mmol/g or more, and preferably 0.30mmol/g or less.

The urethane bond concentration can be calculated by using the following formula 1.

Formula 1:

urethane bond concentration (mmol/g) = [ (NCO content (mass%) of polyisocyanate ÷ 100) × (blending ratio of polyisocyanate (mass%) to total (mass%) of polyol and polyisocyanate constituting urethane resin) ÷ 42 × 1000] + [ (number of urethane bonds inside polyisocyanate ÷ polyisocyanate molecular weight) × (blending ratio of polyisocyanate (mass%) to total (mass%) of polyol and polyisocyanate constituting urethane resin) × 1000 ]) ]

For example, with respect to the urethane bond concentration of the polyurethane resin (A) having a hydroxyl group shown in Synthesis example (a) -1, from the point that the NCO content of toluene diisocyanate is 48.2% by mass, the amount of polyisocyanate added to polyol is 1% by mass, and the number of urethane bonds in the interior is zero,

urethane bond concentration =0.482 x (1/101)/42 x 1000

＝0.11mmol/g。

The weight average molecular weight of the polyurethane resin (a) having a hydroxyl group is preferably 20,000 to 250,000, more preferably 30,000 to 200,000, and still more preferably 50,000 to 100,000.

When the weight average molecular weight is 20,000 or more, the elongation of the resin is further improved and the processability is further improved. When the weight average molecular weight is 250,000 or less, the viscosity of the adhesive solution can be easily prevented from becoming too high, and appearance defects are less likely to occur. Further, by controlling the weight average molecular weight to 50,000 to 100,000, the elongation of the resin and the viscosity of the adhesive solution can be more easily combined and can be used more suitably.

The hydroxyl group value of the hydroxyl group-containing polyurethane resin (A) is preferably from 0.5mgKOH/g to 35mgKOH/g, and more preferably from 1.0mgKOH/g to 15mgKOH/g. The hydroxyl group is used in a crosslinking reaction with the polyisocyanate component (B) described later, and the crosslinking reaction proceeds to increase the molecular weight of the adhesive, thereby improving the heat resistance as a packaging material. The hydroxyl value can be determined, for example, by a method in accordance with Japanese Industrial Standards (JIS) K1557-1.

The glass transition temperature of the polyurethane resin (A) having hydroxyl groups is preferably-20 ℃ to 50 ℃, more preferably-10 ℃ to 30 ℃. When the glass transition temperature is-20 ℃ or higher, the amount of aggregation of the resin is further increased, and the adhesion is further improved. When the glass transition temperature is 50 ℃ or lower, the affinity for the substrate during lamination is further improved, and the adhesion after aging is further improved.

[ polyol ]

The polyol constituting the polyurethane resin (a) having hydroxyl groups is not particularly limited, and may be selected from conventionally known polyols, used alone, or used in combination of two or more. Examples of the polyhydric alcohol include: the polyester polyol is preferably used from the viewpoint of adhesion to a substrate, among them, the polyester polyol, the polyether polyol, the polycarbonate polyol and the acrylic polyol.

(polyester polyol)

The polyester polyol is not limited to the following, and examples thereof include: a polyester polyol obtained by reacting a carboxylic acid component with a hydroxyl component; or a polyester polyol obtained by ring-opening polymerization of a lactone such as polycaprolactone, polypentanolide, or poly (. Beta. -methyl-. Gamma. -valerolactone).

Examples of the carboxylic acid component include: dibasic acids having an aromatic ring such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and phthalic anhydride; aliphatic dibasic acids such as adipic acid, azelaic acid, sebacic acid, succinic acid, glutaric acid, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, and itaconic anhydride; or a dialkyl ester thereof or a mixture thereof.

Examples of the hydroxyl component include: glycols such as ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, butanediol, neopentyl glycol, trimethylolpropane, glycerol, 1, 6-hexanediol, 1, 4-butanediol, 1, 4-cyclohexanedimethanol, 3-methyl-1, 5-pentanediol, 3' -dimethylolheptane, 1, 9-nonanediol, polyoxyethylene glycol, polyoxypropylene glycol, polytetramethylene ether glycol, polyether polyol, polycarbonate polyol, polyolefin polyol, acrylic polyol, and polyurethane polyol; or mixtures thereof.

The carboxylic acid component and the hydroxyl component may be used alone, respectively, but two or more of them are preferably used in combination.

The carboxylic acid component preferably contains 5 to 50 mol% of the aliphatic dibasic acid based on the total carboxylic acid component. When the blending amount of the aliphatic dibasic acid is 5 mol% or more, the solubility of the solvent is further improved, and the viscosity of the resin solution is further lowered. This further improves the coatability. When the amount is 50 mol% or less, the glass transition temperature of the resin can be easily adjusted. This further improves the adhesion. From the same viewpoint, the amount of the aliphatic dibasic acid to be blended is more preferably 25 to 50 mol% based on the total carboxylic acid components.

The weight average molecular weight of the polyol is preferably 10,000 to 30,000. When the weight average molecular weight is 10,000 or more, the adhesiveness to the base material is further improved and the processability is excellent. If the weight average molecular weight is 30,000 or less, the concentration of the hydroxyl group at the polyester polyol end can be easily prevented from being excessively reduced, and the reaction time can be easily prevented from being prolonged when the polyurethane resin (a) having a hydroxyl group is obtained by reacting with a polyisocyanate.

[ polyisocyanate ]

The polyisocyanate constituting the polyurethane resin (a) having hydroxyl groups includes toluene diisocyanate or an adduct of trimethylolpropane to toluene diisocyanate. The obtained packaging material is excellent in moldability and adhesion after a high temperature and high humidity test.

The polyisocyanate may also contain other polyisocyanates than tolylene diisocyanate or an adduct of trimethylolpropane to tolylene diisocyanate, within a range not impairing the effects of the present invention.

Examples of such other polyisocyanates include: aliphatic diisocyanate, alicyclic diisocyanate, aromatic aliphatic diisocyanate, trifunctional or higher polyisocyanate, and various derivatives derived from the above diisocyanates.

Examples of the aliphatic diisocyanate 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-trimethylhexamethylene diisocyanate or 2, 4-trimethylhexamethylene diisocyanate, 2, 6-diisocyanate methylhexanoate.

Examples of the alicyclic diisocyanate include: 1, 4-cyclohexane diisocyanate, 1, 3-cyclohexane diisocyanate, 3-isocyanatomethyl-3, 5-trimethylcyclohexyl isocyanate, 4' -methylenebis (cyclohexyl isocyanate), methyl-2, 4-cyclohexane diisocyanate, methyl-2, 6-cyclohexane diisocyanate, 1, 4-bis (isocyanatomethyl) cyclohexane, 1, 3-bis (isocyanatomethyl) cyclohexane.

Examples of the aromatic diisocyanate include: m-phenylene diisocyanate, p-phenylene diisocyanate, 4 '-diphenyl diisocyanate, 1, 5-naphthalene diisocyanate, 4' -diphenylmethane diisocyanate, 4 '-toluidine diisocyanate, dianisidine diisocyanate, 4' -diphenyl ether diisocyanate.

Examples of the araliphatic diisocyanates include: 1, 3-xylylene diisocyanate or 1, 4-xylylene diisocyanate or a mixture thereof, ω' -diisocyanate-1, 4-diethylbenzene, 1, 3-bis (1-isocyanate-1-methylethyl) benzene or 1, 4-bis (1-isocyanate-1-methylethyl) benzene or a mixture thereof.

Examples of the trifunctional or higher polyisocyanate monomer include: triisocyanates such as triphenylmethane-4,4 ', 4' -triisocyanate, 1,3,5-triisocyanate benzene, 2,4,6-triisocyanate toluene and the like; and tetraisocyanates such as 4,4' -diphenyldimethylmethane-2, 2' -5,5' -tetraisocyanate.

As various derivatives derived from the diisocyanate, there can be used: adducts (adducts) of the diisocyanates with low-molecular-weight polyols having a molecular weight of less than 200, such as ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, 3' -dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol, or castor oil, etc.; trimers (also known as trimers, cyanurate bodies) of the diisocyanates; a biuret body; an allophanate body; further, polyisocyanates having a 2,4, 6-oxadiazinetrione ring obtained from carbon dioxide and the diisocyanate, and the like can also be used.

The reaction temperature of the polyol and the polyisocyanate to obtain the polyurethane resin (a) having hydroxyl groups is preferably in the range of 50 to 200 ℃, more preferably 80 to 150 ℃. In the urethanization reaction, the molar ratio of the isocyanate group of the polyisocyanate to the hydroxyl group in the polyol (the number of moles of the isocyanate group/the number of moles of the hydroxyl group) is preferably 0.1 to 0.9, more preferably 0.3 to 0.8.

< polyisocyanate component (B) >)

The polyisocyanate component (B) and the hydroxyl group in the polyurethane resin (a) having a hydroxyl group undergo a crosslinking reaction, and thus the polyisocyanate component (B) exerts an action of increasing the molecular weight of the adhesive layer and increasing the internal cohesive force which exhibits energy elasticity. In addition, since the isocyanate group can react with water to form a urea bond having a high cohesive force, the cohesive force of the adhesive layer can be increased by performing a self-crosslinking reaction during curing. On the other hand, however, urethane bonds or urea bonds formed by the crosslinking reaction are also hydrogen bonds, and therefore, the urethane bonds or urea bonds have high polarity, and therefore, the compatibility with the resin is poor, and the appearance is deteriorated or defects are caused at the time of processing deformation, but by using a predetermined polyisocyanate and using a polyurethane resin (a) having a urethane bond and a hydroxyl group at a predetermined concentration in combination, an adhesive layer having excellent compatibility, good appearance and toughness can be obtained, and good physical properties can be obtained as a packaging material for an electric storage element.

The polyisocyanate component (B) has an action of enhancing the interaction with the surface of the substrate described later, and the substrate subjected to physical treatment such as corona discharge treatment or chemical treatment such as acid modification is chemically reacted with the reactive functional group in the polyisocyanate (B), whereby a strong interaction can be expressed between the outer layer side adhesive layer and the substrate.

As described above, by using the polyisocyanate component (B), a strong outer layer side adhesive layer can be formed, and the adhesive layer can suppress the stretching movement of the base material accompanying a rapid environmental change, and can maintain the adhesive strength at a high level.

As the polyisocyanate compound (B), the compounds listed in the above-mentioned one of the polyisocyanates constituting the polyurethane resin (a) having a hydroxyl group can be used, and they can be used alone or in combination of two or more.

Among them, preferred are a cyanurate body of a diisocyanate, an adduct body of trimethylolpropane added to a diisocyanate, a biuret type, a prepolymer having an isocyanate residue (an oligomer obtained from a diisocyanate and a polyol), a uretdione (uretdione) body having an isocyanate residue, an allophanate body, or a composite thereof. In terms of being able to combine excellent heat resistance, high cohesive force, and processability in electronic component applications, aromatic isocyanates or derivatives thereof are more preferable.

Further, it is preferable to use the same polyisocyanate as the polyisocyanate component (B) in the polyurethane resin (a) having a hydroxyl group because compatibility is higher.

That is, the polyisocyanate component (B) is preferably an adduct containing toluene diisocyanate or trimethylolpropane added to toluene diisocyanate.

The content of the polyisocyanate component (B) is preferably 10 to 40 parts by mass, more preferably 20 to 30 parts by mass, based on 100 parts by mass of the hydroxyl group-containing polyurethane resin (a). When the polyisocyanate component (B) is 10 parts by mass or more, the molecular weight of the adhesive layer can be more efficiently increased, the internal cohesive force is increased, and high adhesive strength can be easily obtained. When the amount is 40 parts by mass or less, the amount of urethane bonds or urea bonds having high polarity generated by the crosslinking reaction can be appropriately controlled, and the occurrence of defects in the case of deterioration in appearance or deformation due to processing can be easily suppressed.

< production of polyurethane adhesive >

The polyurethane adhesive of the present invention may further contain the following components as other components in the hydroxyl group-containing polyurethane resin (a). The other components may be blended with either the base or the curing agent, or may be added during blending of the base and the curing agent.

(solvent)

In order to adjust the viscosity of the coating liquid to an appropriate level when the polyurethane adhesive is applied to the base material, the polyurethane adhesive may contain a solvent in a range that does not affect the base material in the drying step. Examples of the solvent 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; water, and the like. These solvents may be used alone or in combination of two or more.

(reaction Accelerator)

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

(silane coupling agent)

The polyurethane adhesive may further contain a silane coupling agent in order to improve the adhesive strength to a metal material such as a metal foil. Examples of the silane coupling agent include: trialkoxysilanes having a vinyl group such as vinyltrimethoxysilane and vinyltriethoxysilane; trialkoxysilanes having an amino group such as 3-aminopropyltriethoxysilane and N- (2-aminoethyl) 3-aminopropyltrimethoxysilane; trialkoxysilanes having a glycidyl group such as 3-glycidoxypropyltrimethoxysilane, 2- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, and 3-glycidoxypropyltriethoxysilane.

The content of the silane coupling agent is preferably 0.1 to 5 parts by mass, more preferably 0.5 to 3 parts by mass, per 100 parts by mass of the solid content of the hydroxyl group-containing polyurethane resin (a). The adhesion strength to the metal foil can be further improved by adding the silane coupling agent in the above range.

(epoxy resin)

In order to improve the adhesive strength to a metal material such as a metal foil, an epoxy resin may be further added to the polyurethane adhesive. In particular, when an epoxy resin is added to the polyurethane resin (a) having a polyester skeleton, the moist heat resistance can be further improved by reacting with an acid generated in hydrolysis during the moist heat resistance.

The epoxy resin is not limited to the following, and examples thereof include: bisphenol a-type epoxy resin, bisphenol F-type epoxy resin, phenol novolac-type epoxy resin, cresol novolac-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 singly or in combination of two or more.

Among them, an epoxy resin having a weight average molecular weight of 400 to 10,000 is preferable from the viewpoint of adhesion and moist heat resistance. From the viewpoint of adhesion and moist heat resistance, the amount of the epoxy resin blended is preferably 5 to 50 parts by mass, more preferably 10 to 20 parts by mass, per 100 parts by mass of the hydroxyl group-containing polyurethane resin (a). By setting the amount to 5 parts by mass or more, the moist heat resistance can be more effectively improved, and by setting the amount to 50 parts by mass or less, the hardness of the adhesive layer can be appropriately softened, and sufficient adhesion can be easily expressed.

(phosphoric acid or a derivative thereof)

The polyurethane adhesive may contain phosphoric acid or a phosphoric acid derivative in order to improve the adhesive strength to a metal material such as a metal foil. The phosphoric acid may have at least one free oxygen acid, and examples thereof include phosphoric acids such as hypophosphorous acid (hypophosphorous acid), phosphorous acid, orthophosphoric acid (orthophosphoric acid), and hypophosphoric acid (hypophosphoric acid); condensed phosphoric acids such as metaphosphoric acid, pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid (ultraphosphoric acid). Examples of the derivative of phosphoric acid include a derivative obtained by partially esterifying the phosphoric acid with an alcohol while leaving at least one free oxoacid. Examples of the alcohol include: aliphatic alcohols such as methanol, ethanol, ethylene glycol and glycerin; and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglucinol (phloroglucinol). The phosphoric acid or a derivative thereof may be used alone or in combination of two or more. The amount of the phosphoric acid or a derivative thereof added is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, and still more preferably 0.05 to 1 part by mass, based on 100 parts by mass of the hydroxyl group-containing polyurethane resin (a).

In order to improve the laminated appearance of the packaging material, the polyurethane adhesive may further contain a leveling agent or an antifoaming agent. As the leveling agent, there may be mentioned: polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl-containing polydimethylsiloxane, polyether ester-modified hydroxyl-containing polydimethylsiloxane, acrylic copolymer, methacrylic copolymer, polyether-modified polymethylalkylsiloxane, alkyl acrylate copolymer, alkyl methacrylate copolymer, lecithin (lecithin), and the like.

Examples of the defoaming agent include known materials such as silicone resins, silicone solutions, and copolymers of alkyl vinyl ethers and alkyl acrylates and alkyl methacrylates.

The polyurethane adhesive may contain various additives within a range not impairing the effects of the present invention. Examples of additives include: inorganic fillers such as silica, alumina, mica, talc, aluminum flakes and glass flakes, lamellar inorganic compounds, stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, hydrolysis inhibitors, etc.), rust inhibitors, thickeners, plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, fillers, crystal nucleating agents, catalysts for adjusting the hardening reaction, and the like.

< production of packaging Material for electric storage element >

The method for producing the packaging material for an electric storage element of the present invention is not particularly limited, and can be produced by a known method.

For example, the production can be carried out by laminating the outer layer side resin film layer (1) and the metal foil layer (3) using a polyurethane adhesive for forming the outer layer side adhesive layer (2) to obtain an intermediate laminate having a structure of the outer layer side resin film layer (1)/the outer layer side adhesive layer (2)/the metal foil layer (3), and then laminating the heat-seal layer (5) on the metal foil layer (3) surface of the intermediate laminate using the inner layer side adhesive (hereinafter referred to as production method 1).

Alternatively, the metal foil layer (3) and the heat-seal layer (5) may be laminated using an inner layer side adhesive to obtain an intermediate laminate having a structure of the metal foil layer (3)/the inner layer side adhesive layer (4)/the heat-seal layer (5), and then the metal foil layer (3) and the outer layer side resin film layer (1) of the intermediate laminate may be laminated using the polyurethane adhesive to produce the laminate (hereinafter referred to as production method 2).

In the case of the production method 1, it is preferable that the polyurethane adhesive is applied to one surface of either the outer layer side resin film layer (1) or the metal foil layer (3), the solvent is evaporated, then the other substrate is bonded to the uncured outer layer side adhesive layer under heat and pressure, and then aging is performed at normal temperature (e.g., 25 ℃) to less than 100 ℃ to cure the outer layer side adhesive layer. When the aging temperature is less than 100 ℃, thermal shrinkage of the outer layer side resin film layer (1) can be easily prevented, and therefore, a reduction in elongation at break or stress at break, which affects molding, and a reduction in molding productivity due to film curling can be easily prevented.

The coating weight of the outer layer side adhesive after drying is preferably 1g/m ² ～15g/m ² Left and right.

In the packaging material for an electric storage element of the present invention, even if the adhesive is a thin film, the packaging material has excellent adhesion strength and moldability after a long-term durability test at high temperature and high humidity, and does not cause appearance defects such as floating between layers. Specifically, the packaging material for an electric storage element of the present inventionIn the (B) adhesive, even if the coating weight after drying of the adhesive is 3g/m ² The coating weight was further reduced to 2g/m ² Hereinafter, the adhesive strength, moldability and interlayer floating suppression after the high-temperature high-humidity long-term durability test are also excellent, and the excellent effect of being able to achieve both the reduction in thickness and moldability of the adhesive and the interlayer adhesive strength after the high-temperature high-humidity long-term durability test is exhibited.

In the case of production method 2, the polyurethane adhesive may be applied to either the outer layer side resin film layer (1) or the metal foil layer (3) surface of the intermediate laminate.

Examples of the method for forming the outer layer side adhesive layer include a method using a notch roll coater, a dry laminator, a knife roll coater, a die coater, a roll coater, a bar coater, a gravure roll coater, a reverse roll coater, a blade coater, a gravure coater, a micro gravure coater, and the like.

< outer layer side resin film layer (1) >

The outer resin film layer (1) is not particularly limited, and a stretched film containing polyamide or polyester is preferably used. Further, the coloring may be carried out by using a pigment such as carbon black or titanium oxide. The non-laminated surface of the outer-layer-side resin film layer (1) may be coated with a coating agent or a slip agent for the purpose of preventing damage or electrolyte resistance, or may be coated with a printing ink for the purpose of design. In addition, the outer layer side resin film layer (1) may be formed by laminating two or more films in advance. The thickness of the outer resin film layer (1) is not particularly limited, but is preferably 12 to 100. Mu.m.

< Metal foil layer (3) >)

The metal foil layer (3) is not particularly limited, but is preferably an aluminum foil layer. The thickness of the metal foil layer (3) is not particularly limited, but is preferably 20 to 80 μm. The surface of the metal foil layer (3) is preferably subjected to a known corrosion prevention treatment such as a phosphate chromate treatment, a chromate treatment, a chromium oxide treatment, a zinc phosphate treatment, a zirconium oxide treatment, a titanium phosphate treatment, a hydrofluoric acid treatment, a cerium (cerium) treatment, or a hydrotalcite (hydrotalcite) treatment. By performing the anticorrosive treatment, corrosion deterioration of the surface of the metal foil due to the electrolytic solution of the battery can be suppressed. Further, it is preferable that the surface of the anticorrosive coating is treated by baking a known organic primer such as a phenol resin, an amide resin, an acrylic resin, polyvinyl alcohol, or a coupling agent to a metal at a high temperature of about 200 ℃. By applying the organic primer treatment, the metal foil and the adhesive can be more firmly adhered to each other, and the floating between the metal foil and the adhesive can be further suppressed.

< Heat sealing layer (5) >)

The heat-sealing layer (5) is not particularly limited, and is preferably an unstretched film comprising 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 μm to 150 μm.

< inner layer side adhesive layer (4) >)

The adhesive for forming the inner layer side adhesive layer (4) is not particularly limited, but is preferably an adhesive in which the adhesive strength between the metal foil layer (3) and the heat seal layer (5) is not reduced by the electrolyte of the power storage element, and a known adhesive can be used.

The inner layer side adhesive layer (4) can be formed by, for example, applying an adhesive agent composed of a combination of a polyolefin resin and a polyisocyanate and an adhesive agent composed of a combination of a polyol and a polyisocyanate to the metal foil layer (3) using a gravure coater or the like, drying the solvent, laminating the heat seal layer (5) on the adhesive layer under heat and pressure, and then aging at normal temperature or under heat.

Alternatively, an adhesive such as acid-modified polypropylene may be melt-extruded onto the metal foil layer (3) by a T-die extruder to form an adhesive layer, the heat-seal layer (5) may be superimposed on the adhesive layer, and the metal foil layer (3) and the heat-seal layer (5) may be bonded to each other to form the inner layer-side adhesive layer (4).

When both the outer layer side adhesive layer (2) and the inner layer side adhesive layer (4) need to be aged, a laminate having a structure in which an outer layer side resin film layer (1), an uncured outer layer side adhesive layer, a metal foil layer (3), an uncured inner layer side adhesive layer, and a heat seal layer (5) are laminated in this order from the outside may be obtained and then aged together.

< Container for electric storage element >

The container for an electric storage device of the present invention can be obtained by molding the outer layer side resin film layer (1) to form a convex surface and the heat-seal layer (5) to form a concave surface, using the packaging material for an electric storage device of the present invention. In the present invention, the "concave surface" refers to a surface having a depression capable of accommodating an electrolyte solution therein when a flat packaging material for an electric storage element is molded into a tray shape as shown in fig. 2, and the "convex surface" refers to a back surface of the surface having the depression.

< storage element >

The electric storage device of the present invention is formed using the capacitor for electric storage device, and examples thereof include secondary batteries such as lithium ion batteries, nickel hydrogen batteries, and lead storage batteries, and electrochemical capacitors such as electric double layer capacitors.

A general power storage element includes: in the electric storage device of the present invention, the container for the electric storage device is used for the container for housing. The container for storage is formed from a packaging material for an electric storage element such that the heat seal layers (5) are on the inside, and can be obtained by overlapping the heat seal layers (5) of two packaging materials so as to face each other and heat-welding the peripheral edge portions of the overlapping packaging materials, or by folding and overlapping one packaging material and heat-welding the peripheral edge portions of the packaging material in the same manner.

[ examples ]

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

< determination of Acid Value (AV) >

About 1g of a sample (a polyester polyol solution) was precisely measured in a stopcock flask, and 100ml of a toluene/ethanol (volume ratio: toluene/ethanol = 2/1) mixture was added to dissolve the sample. Phenolphthalein test solution was added thereto as an indicator and held for 30 seconds. Then, the solution was titrated with a 0.1N alcoholic potassium hydroxide solution until the solution became pale red, and the acid value (mgKOH/g) was determined by the following equation.

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

Wherein, S: sample Collection volume (g)

a: consumption (ml) of 0.1N alcoholic potassium hydroxide solution

F: titre of 0.1N alcoholic potassium hydroxide solution

< determination of hydroxyl value (OHV) >

About 1g of a sample (polyester polyol, hydroxyl group-containing urethane resin, or the like) was precisely measured in a stopcock flask, and 100ml of a toluene/ethanol (volume ratio: toluene/ethanol = 2/1) mixed solution was added and dissolved. Further, 5ml of an acetylating agent (a solution prepared by dissolving 25g of acetic anhydride in pyridine to have a capacity of 100 ml) was added and stirred for about 1 hour. Phenolphthalein test solution was added thereto as an indicator for 30 seconds. Then, the solution was titrated with a 0.5N alcoholic potassium hydroxide solution until the solution became pale red, and the hydroxyl value (mgKOH/g) was determined by the following equation.

A hydroxyl value of (mgKOH/g) = [ { (b-a) × F × 28.05}/S ] + D

Wherein, S: sample Collection volume (g)

a: consumption (ml) of 0.5N alcoholic potassium hydroxide solution

b: consumption (ml) of 0.5N alcoholic potassium hydroxide solution for blank experiment

F: titre of 0.5N alcoholic potassium hydroxide solution

D: acid value (mgKOH/g)

< determination of weight average molecular weight (Mw) >)

The weight average molecular weight was a value in terms of standard polystyrene measured in such a manner that Sodeks (Shodex) (registered trademark) (manufactured by Showa Denko K.K.), a column were used: KF-805L, KF-803L, and KF-802 (all trade names, manufactured by showa electrician) set the column temperature to 40 ℃, the flow rate to 0.2 ml/min using Tetrahydrofuran (THF) as an eluent, the detection to infrared (RI) detection, and the sample concentration to 0.02 mass%.

< glass transition temperature (Tg) >

The glass transition temperature was measured by a Differential Scanning Calorimeter (DSC). Specifically, about 2mg of the compound to be measured was weighed on an aluminum pan, the aluminum pan was placed on a DSC measurement holder, the endothermic peak of the graph obtained under a temperature rise condition of 5 ℃/min was read, and the peak temperature at that time was taken as the glass transition temperature.

< Synthesis of polyester polyol >

(polyester 1)

80.0 parts of isophthalic acid, 160.1 parts of terephthalic acid, 357.2 parts of sebacic acid, 68.8 parts of ethylene glycol, 115.4 parts of neopentyl glycol and 174.5 parts of 1, 6-hexanediol were charged, and esterification reaction was carried out at 170 ℃ to 230 ℃ for 6 hours. After a predetermined amount of water was distilled off, 0.13 part of tetraisobutyl titanate was added thereto, and transesterification was carried out at 230 to 250 ℃ for 3 hours at 1.3hPa to 2.6hPa under a gradually reduced pressure to obtain polyester 1 which is a polyester polyol having a number average molecular weight (Mn) of 12,000, a weight average molecular weight (Mw) of 28,000, a molecular weight distribution (Mw/Mn) of 2.33, a hydroxyl value of 12.2mgKOH/g, an acid value of 0.2mgKOH/g, and a glass transition temperature of-15 ℃.

Assuming that the excessive hydroxyl components are distilled off almost equally and the total amount of the carboxylic acid component and the hydroxyl components is 200 mol%, the composition of the obtained polyester 1 is shown in table 1, and is isophthalic acid: terephthalic acid: sebacic acid: ethylene glycol: neopentyl glycol: 1, 6-hexanediol =15:30:55:30:30:40 (mol%).

(polyesters 2 to 11)

The carboxylic acid component and the hydroxyl component were reacted in the same manner as in polyester 1 so that the composition shown in table 1 was obtained as the mol% of each component when the total amount of the carboxylic acid component and the hydroxyl component of the obtained polyester polyol was 200 mol%, thereby obtaining polyesters 2 to 11.

[ Table 1]

The abbreviations in table 1 are as follows.

IPA: isophthalic acid

TPA: terephthalic acid (TPA)

AdA: adipic acid

And (5) SeA: sebacic acid

AzA: azelaic acid

EG: ethylene glycol

NPG: neopentyl glycol

1,6-HD:1, 6-hexanediol

BEPG: butyl ethyl propylene glycol

< Synthesis of hydroxyl group-containing polyurethane resin >

(Carbamate (a) -1)

100 parts of the polyester 1 and 100 parts of toluene were charged into a 1 liter four-necked flask, heated to 100 ℃ and stirred until the solution became homogeneous. To this, 1.0 part of toluene diisocyanate and 0.15 part of dibutyltin dilaurate were added and a reaction was carried out for 4 hours. After the reaction, 50 parts of methyl ethyl ketone was added to obtain a urethane (a) -1 solution as a hydroxyl group-containing polyurethane resin having a urethane bond concentration of 0.11mmol/g, mw of 36,000, tg of-12 ℃, a hydroxyl value of 9.0mgKOH/g and a nonvolatile content of 40%.

(Carbamate (a) -2-Carbamate (a) -19)

Except for changing the blending amounts shown in table 2, the polyol and polyisocyanate were reacted in the same manner as for urethane (a) -1 to obtain urethane (a) -2 to urethane (a) -19 as a hydroxyl group-containing polyurethane resin.

[ Table 2]

The abbreviations in table 2 are as follows.

NPG: neopentyl glycol

TDI: toluene diisocyanate (Crosstide T-80 (trade name), manufactured by Tosoh Co., ltd.)

TDI-TMP: trimethylolpropane adduct of tolylene diisocyanate (Crosstide L (trade name), manufactured by Tosoh Co., ltd., solid content of 75%, NCO content of 13.2%)

MDI:4,4' -diphenylmethane diisocyanate (Millinotide (MILLIONATE) MT (trade name), manufactured by Tosoh Co., ltd.)

HDI: hexamethylene diisocyanate (Desmodur (registered trademark) H (trade name), manufactured by Covestro corporation)

IPDI: isophorone diisocyanate (Desmodur I (trade name), manufactured by Covestro corporation)

Production of packaging Material for Electrical storage device

[ example 1]

250 parts (100 parts in terms of solids) of the urethane (a) -1 solution and 1.0 part of glycidoxypropyltrimethoxysilane as an additive were charged, and after stirring for 30 minutes, 40 parts (30 parts in terms of solids) of cronate L (product name, manufactured by Tosoh corporation, solid content 75%, NCO content 13.2%) were charged and diluted with methyl ethyl ketone to prepare an adhesive solution having a solid content of 30%.

The adhesive solution was applied to one surface of an aluminum foil having a thickness of 40 μm as an outer layer side adhesive layer (2) using a dry laminator, and after volatilizing the solvent, an extended polyamide film having a thickness of 30 μm was laminated to obtain an intermediate laminate. The coating weight of the adhesive after drying was set to 2g/m ² And 4g/m ² 。

Next, an adhesive for an inner layer side adhesive layer described later was applied to the other surface of the aluminum foil of the obtained intermediate laminate using a dry laminator, and after evaporating the solvent, an unstretched polypropylene film having a thickness of 30 μm was laminated to obtain a laminate. The coating weight of the adhesive after drying was set to 4g/m ² 。

Next, the outer layer side and inner layer side adhesive layers were hardened by aging for 7 days under conditions of 60 ℃, 30% rh (relative humidity) and 60 ℃, 90% rh, to obtain a battery packaging material having a structure of outer layer side resin film layer (1)/outer layer side adhesive layer (2)/metal foil layer (3)/inner layer side adhesive layer (4)/heat-seal layer (5).

(adhesive for inner layer adhesive layer)

AD-502 (trade name, manufactured by Toyo Morton (stock), polyester polyol) was used as a base compound, CAT-10L (trade name, manufactured by Toyo Morton (stock), isocyanate-based curing agent) was used as a curing agent, the base compound/curing agent =100/10 (mass ratio) was blended, the solid content concentration was adjusted to 30% with ethyl acetate, and the resultant was used as an inner layer side adhesive layer adhesive.

Examples 2 to 23 and comparative examples 1 to 9

A battery packaging material was obtained in the same manner as in example 1, except that the blending amount (parts) in tables 3 to 5 was changed.

< evaluation of packaging Material for Electrical storage device >

The following evaluations were performed on the obtained packaging material for an electric storage device. The results are shown in tables 3 to 5.

[ appearance evaluation of packaging Material ]

The coating weight of the outer layer side adhesive after drying was 4g/m ² The aging conditions were 60 ℃ 30% RH, 7 days and 60 ℃ 90% RH, 7 days, and the appearance of the battery packaging material was visually observed and evaluated according to the following criteria.

A: no whitening or foaming (good)

B: there was some whitening, but foaming was not seen (could be used)

C: visible whitening or foaming (not applicable)

[ lamination Strength (before Wet Heat test) ]

The coating weight of the outer layer side adhesive after drying was 2g/m ² And 4g/m ² The battery packaging material was cut into a size of 200mm × 15mm under aging conditions of 60 ℃, 30% rh, and 7 days, and a T-type peel test was performed using a tensile tester to measure the peel strength (N/15 mm width) between the stretched polyamide film and the aluminum foil. The measurement was carried out at a load rate of 300 mm/min in an environment of 20 ℃ and 65% RHThe evaluation was performed based on the average of five test pieces according to the following criteria.

S: the average peel strength was 7N or more (very good)

A: the average value of the peel strength was 4N or more and less than 7N (good)

B: the average peel strength is 2N or more and less than 4N (usable)

C: average value of peel strength less than 2N (unusable)

[ lamination Strength (after Wet Heat test) ]

The coating weight of the outer layer side adhesive after drying was 2g/m ² And 4g/m ² The battery packaging materials aged at 60 ℃ and 30% RH for 7 days were placed in a constant temperature and humidity chamber in an atmosphere of 85 ℃ and 85% RH, allowed to stand for 168 hours, then taken out from the chamber, allowed to stand for 2 hours in an atmosphere of 20 ℃ and 65% RH, and then subjected to the same procedure as before the moist heat test to evaluate the lamination strength on the same basis.

[ evaluation of moldability ]

The coating weight of the outer layer side adhesive after drying was 2g/m ² The aging conditions were 60 ℃, 30% RH and 7 days, and the battery packaging material was cut into 80mm × 80mm pieces and formed into blanks. The above-mentioned blank was subjected to one-stage molding by drawing with a straight die having no limit to the molding height so that the stretched polyamide film was located on the outer side, and the moldability was evaluated based on the maximum molding height at which the aluminum foil was not broken or the floating between the respective layers was not generated, according to the following criteria.

The punch shape of the die used was a square with one side of 30mm, the corner R was 2mm, the punch shoulder R was 1mm, the die hole shape of the die used was a square with one side of 34mm, the die hole corner R was 2mm, the die hole shoulder R was 1mm, and the clearance between the punch and the die hole was 2mm on one side, and an inclination corresponding to the molding height was generated due to the clearance.

S: maximum molding height of 6mm or more (very good)

A: the maximum molding height is 4mm or more and less than 6mm (good)

B: the maximum molding height is more than 2mm and less than 4mm (can be used)

C: maximum molding height less than 2mm (unusable)

[ moist Heat resistance of molded article ]

The coating weight of the outer layer side adhesive after drying was 2g/m ² The battery packaging material was cut into 80mm by 80mm pieces under aging conditions of 60 ℃ and 30% RH for 7 days to prepare blanks. The preform was stretched at a molding height of 3mm by a straight die with no limitation on the molding height so that the stretched polyamide film was located on the outer side, and one-stage molding was performed to obtain a molded article.

Next, the molded article was placed in a constant temperature and humidity vessel at 85 ℃ and 85% RH for 168 hours, and then taken out from the constant temperature and humidity vessel, and whether or not floating had occurred was visually confirmed, and the evaluation was made according to the following criteria.

The punch shape of the die used was a square with a side of 30mm, the corner R was 2mm, the punch shoulder R was 1mm, the die hole shape of the die used was a square with a side of 34mm, the die hole corner R was 2mm, and the die hole shoulder R was 1mm.

A: no floating (good)

B: one of the four sides floats (can be used)

C: the floating of the four sides is generated at the upper side (not used)

[ Heat resistance of molded article ]

The conditions of standing were changed from 85 ℃ and 85% RH for 168 hours to 120 ℃ and 168 hours, and whether or not the molded article was floated was visually checked in the same manner as in the evaluation of the wet heat resistance, and the evaluation was carried out according to the following criteria.

A: no floating (good)

B: one side of the four sides floats (can be used)

C: the floating of the four sides (unusable)

[ Table 4]

[ Table 5]

The abbreviations in tables 3 to 5 are as follows.

SC-1: glycidoxypropyltrimethoxysilane

SC-2: glycidoxypropyltriethoxysilane

EP-1: bisphenol A type epoxy resin (trade name: JER834, manufactured by Mitsubishi chemical corporation, epoxy equivalent 250, molecular weight about 470)

EP-2: bisphenol A type epoxy resin (trade name: JER1002, manufactured by Mitsubishi chemical corporation, epoxy equivalent 650, molecular weight about 1,200)

DBTDL: dibutyl tin dilaurate

NCO-1: trimethylolpropane adduct of tolylene diisocyanate (trade name: croton's L, manufactured by Tosoh corporation, nonvolatile content 75%, NCO content 13.2%)

NCO-2: trimethylolpropane adduct of hexamethylene diisocyanate (trade name: takenate D-160N, manufactured by Mitsui chemical Co., ltd., NCO content 12.6%, non-volatile content 75%)

NCO-3: isocyanurate structural body of isophorone diisocyanate (trade name: vestatat (registered trademark) T1890/100, manufactured by evanik corporation, NCO content 17.3%)

From the results in table 3, it is understood that the packaging material using a predetermined hydroxyl group-containing polyurethane resin as the main agent for forming the outer layer side adhesive layer has good compatibility with polyisocyanate as the curing agent, and that even when curing is performed under high humidity conditions of 60 ℃, 90% rh, appearance defects such as foaming and clouding do not occur. In addition, due to the compatibility of the main agent and the hardening agentExcellent in that the cohesive force of the outer layer side adhesive layer is improved even when the coating amount of the outer layer side adhesive layer is 2g/m ² The film of (2) is also excellent in the lamination strength and moldability of the packaging material.

In particular, in example 4, the urethane bond concentration, the weight average molecular weight, and the glass transition temperature of the polyurethane resin (a) having a hydroxyl group are appropriate, and therefore, the laminate strength and the processability are excellent. The reason for this is presumably that the compatibility with the curing agent is high, and an adhesive layer having a high cohesive force is obtained.

In addition, examples 4 to 6 using 5 to 50 mol% of the aliphatic dibasic acid were superior in coating appearance and moist heat resistance to example 9 not using the aliphatic dibasic acid.

On the other hand, in comparative example 1, the urethane bond concentration was high, and the adhesive had high viscosity, so that it was difficult to apply the adhesive, and the lamination strength was also decreased. Therefore, the deformation during molding cannot be followed, and floating occurs. In comparative examples 2 and 6, since the urethane bond concentration was low, the laminate strength was low, and the heat resistance was insufficient in the processing under film.

In comparative examples 3 to 5, the polyisocyanate constituting the polyurethane resin (a) having a hydroxyl group was changed, and the compatibility with the curing agent was lowered, and thus appearance defects and a reduction in lamination strength were caused in hot and humid conditions.

Comparative example 7 corresponds to example 2018/117080 in which toluene diisocyanate is used, but the urethane bond concentration is high, the appearance is poor, and the lamination strength after wet heating is reduced.

In comparative example 8, the main agent did not contain the polyurethane resin (a) having a hydroxyl group, and thus poor appearance was generated.

Comparative example 9 corresponds to the example of Japanese patent application laid-open No. 2014-091770, but as in comparative example 8, since the main agent does not contain a urethane bond, appearance defects of the coating film are likely to occur during curing under high humidity conditions, and the adhesive strength is likely to decrease in the case of a thin film. In addition, as in comparative example 8, the deformation during molding could not be followed, and floating occurred.

Claims

1. A packaging material for an electric storage element has a structure in which at least 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 laminated in this order from the outside, and the packaging material for an electric storage element has a structure in which the outer layer side resin film layer, the outer layer side adhesive layer (2), the metal foil layer (3), the inner layer side adhesive layer (4), and the heat seal layer (5) are laminated in this order from the outside

the urethane bond concentration of the polyurethane resin (A) having a hydroxyl group is 0.10mmol/g to 0.40mmol/g.

2. The packaging material for power storage elements according to claim 1, wherein the weight average molecular weight of the polyurethane resin (a) having a hydroxyl group is 50,000 to 250,000.

3. The packaging material for an electricity storage element according to claim 1 or 2, wherein the hydroxyl group value of the polyurethane resin (a) having a hydroxyl group is from 0.5mgKOH/g to 35mgKOH/g.

4. The packaging material for power storage elements according to any one of claims 1 to 3, wherein the polyurethane resin (A) having a hydroxyl group is a reaction product of a polyester polyol having a weight average molecular weight of 10,000 to 30,000 and a polyisocyanate.

5. A container for an electric storage device, which is formed from the packaging material for an electric storage device according to any one of claims 1 to 4, wherein the outer layer side resin film layer ((1)) forms a convex surface and the heat seal layer ((5)) forms a concave surface.

6. An electric storage device comprising the container for an electric storage device according to claim 5.