JP7052913B1 - Packaging materials for power storage devices, containers for power storage devices and power storage devices - Google Patents

Abstract

PROBLEM TO BE SOLVED: To package for a power storage device which has excellent moldability and does not cause appearance defects such as floating between layers even if the adhesive is a thin film, the adhesive strength between layers does not decrease after a high temperature and high humidity / long-term durability test. Providing materials, containers for power storage devices, and highly reliable power storage devices. SOLUTION: 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 arranged in this order from the outside. A polyurethane adhesive having a laminated structure in which the outer layer side adhesive layer (2) contains a main agent (A) containing a polyurethane resin (a) having a hydroxyl group and a curing agent containing a polyisocyanate component (B). The polyurethane resin (a) formed from the agent and having a hydroxyl group is a reaction product of a polyester polyol and a polyisocyanate, and has an ester bond concentration of 9.20 to 10.50 mmol / g. Used as packaging material. [Selection diagram] Fig. 1

Description

The present invention relates to a packaging material for a power storage device for forming a container for a power storage device such as a lithium ion battery, and the packaging material for the power storage device having a good appearance and excellent adhesive strength and moldability. The present invention relates to a container for a power storage device made of a material, and a power storage device.

Due to the rapid growth of electronic devices such as mobile phones and portable personal computers, the demand for storage devices such as secondary batteries such as lithium ion batteries and nickel hydrogen batteries and electric chemical capacitors such as electric double layer capacitors has increased. Among these, small lithium-ion batteries are attracting attention because of their high energy density and light weight. Conventionally, metal cans have been used as the exterior body of lithium-ion batteries, but from the viewpoint of weight reduction and productivity, packaging materials in which plastic films, metal foils, etc. are laminated are becoming mainstream.

Patent Document 1 has a structure in which a heat-resistant stretched resin layer, an adhesive layer, an aluminum layer, and a thermoplastic non-stretched resin layer are sequentially laminated, and the adhesive layer has a glass transition temperature of −20 to 45 ° C. A packaging material for a battery case, which is composed of a cured product of an adhesive composition containing the polyester resin shown and 10 to 70 parts by mass of a toluene diisocyanate-based curing agent with respect to 100 parts by mass of the polyester resin. Is disclosed.

Further, in Patent Document 2, the outer layer side resin film layer, the outer layer side adhesive layer, the metal foil layer, the inner layer side adhesive layer and the heat seal layer are sequentially laminated, and the outer layer side adhesive layer is a specific glass. A packaging material for a battery is disclosed, which is formed of an adhesive containing two kinds of polyester polyols having a transition temperature, a polyisocyanate, and a silane coupling agent.

Further, in Patent Document 3, an adhesive containing a polyol composition obtained by chain-extending a polyester polyol with polyisocyanate and a polyisocyanate composition is used, and the coating amount after drying is 4 g / m ² . The packaging material for batteries, in which the base material layer on the outer layer side and the metal foil layer are bonded together, is described.

Patent Document 4 discloses a laminated adhesive having a limited content of urethane bonds and isocyanate groups for the purpose of improving processability, moldability of a composite film, moisture heat resistance, and appearance.

Japanese Unexamined Patent Publication No. 2013-149562 Japanese Unexamined Patent Publication No. 2014-091770 International Publication No. 2018/11080 Japanese Unexamined Patent Publication No. 2016-196580

In recent years, along with the expansion of applications such as in-vehicle and household power storage, there is a demand for a large capacity of a secondary battery, and a packaging material for a power storage device is required to have good moldability. Further, in in-vehicle applications, further weight reduction is required, and even if the adhesive is made into a thin film, the adhesive strength between the layers of each plastic film or metal foil of the packaging material is maintained even after the molding process and the long-term durability test. Furthermore, it is required that there is no abnormality in the appearance.

However, since the packaging materials described in Patent Documents 1 and 2 use a urethane-based adhesive in which an isocyanate component is excessively blended in the adhesive layer, a urea bond is formed by the reaction between the excess isocyanate group and water. Since the resin to be possessed is produced and the urea bond-containing resin is inferior in compatibility with the urethane adhesive, there are problems that the appearance is poor and deep molding is difficult when used as a packaging material.

Since the packaging material described in Patent Document 3 does not use a polyurethane resin having a specific constituent component and urethane bond concentration, the adhesive is made thinner, and the layers after the moldability, high temperature and high humidity / long-term durability test are applied. There is a problem that it is difficult to achieve both the adhesive strength and the adhesive strength of the film. In addition, there is a problem that the solubility in a solvent such as ethyl acetate is poor, and the main agent solidifies during long-term storage, making stable coating impossible.

Patent Document 4 describes a laminated adhesive using a polyurethane resin having a urethane bond and an isocyanate content limited, but has a problem that the storage elastic modulus is low and it is difficult to thin the adhesive.

Therefore, according to the present invention, even if the adhesive is a thin film, the adhesive strength between the layers does not decrease after the high temperature and high humidity / long-term durability test, the moldability is excellent, and the appearance defects such as floating between the layers do not occur. It is an object of the present invention to provide a packaging material, a container for a power storage device using the packaging material, and a highly reliable power storage device.

As a result of diligent studies to solve the above problems, it was found that the above problems can be solved by the following embodiments, and the present invention has been completed.

One embodiment of the present invention includes 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). However, a packaging material for a power storage device having a structure in which the layers are laminated from the outside in this order, wherein the outer layer side adhesive layer (2) contains a polyurethane resin (a) having a hydroxyl group and a main agent (A). It is formed from a polyurethane adhesive containing a curing agent containing a polyisocyanate component (B), and the polyurethane resin (a) having a hydroxyl group is a reaction product of a polyester polyol and a polyisocyanate. The present invention relates to a packaging material for a power storage device, characterized in that the ester bond concentration is 9.20 to 10.50 mmol / g.

Another embodiment of the present invention relates to the packaging material for a power storage device, wherein the polyurethane resin (a) having a hydroxyl group has a urethane bond concentration of 0.10 to 0.90 mmol / g or less.

Another embodiment of the present invention relates to the packaging material for a power storage device, wherein the polyurethane resin (a) having a hydroxyl group has a hydroxyl value of 0.5 to 20 mgKOH / g.

In another embodiment of the present invention, the polyurethane resin (a) having a hydroxyl group is a reaction product of a polyester polyol having a weight average molecular weight of 5,000 to 30,000 and a polyisocyanate, for the storage device. Regarding packaging materials.

Another embodiment of the present invention is a container for a power storage device formed of a packaging material for a power storage device formed of the packaging material for a power storage device, and the outer layer side resin film layer (1) constitutes a convex surface. The present invention relates to a container for a power storage device, wherein the heat seal layer (5) constitutes a concave surface.

Another embodiment of the present invention relates to a power storage device including the container for the power storage device.

In the present invention, since the main agent having a predetermined ester bond concentration and excellent storage stability is used, an adhesive layer with few coating defects can be obtained, and even if the adhesive is a thin film, even after a high temperature, high humidity and long-term durability test. For packaging materials for power storage devices that do not reduce the adhesive strength between layers, have excellent moldability, and do not cause appearance defects such as floating between layers, containers for power storage devices using the packaging materials, and reliability. It is possible to provide an excellent power storage device.

It is a schematic cross-sectional view of the packaging material for a power storage device of this invention. It is a schematic perspective view of one aspect (tray shape) of the container for a power storage device of this invention.

<Packaging material for power storage devices>
The packaging material for a power storage device of the present invention has 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) is a packaging material for a power storage device having a structure in which the layers are laminated from the outside in this order, and the outer layer side adhesive layer (2) is a main agent (A) containing a polyurethane resin (a) having a hydroxyl group. , The polyurethane resin (a) having a hydroxyl group is formed from a polyurethane adhesive containing a curing agent containing a polyisocyanate component (B), and is a reaction product of a polyester polyol and a polyisocyanate. The ester bond concentration is 9.20 to 10.50 mmol / g.
Hereinafter, the present invention will be described in detail with reference to a preferred embodiment as an example.

<Outer layer side adhesive layer (2)>
The outer layer side adhesive layer (2) in the present invention is formed of a polyurethane adhesive containing a main agent (A) containing a polyurethane resin (a) having a hydroxyl group and a curing agent containing a polyisocyanate component (B). ..
First, the main agent will be described. The main agent and the curing agent may contain known additives as long as the effects of the present invention are not impaired.

<Polyurethane resin (a) having a hydroxyl group>,
The polyurethane resin (a) having a hydroxyl group is a reaction product of a polyester polyol and a polyisocyanate, and is characterized by having an ester bond concentration of 9.20 to 10.50 mmol / g. The polyurethane resin (a) having a hydroxyl group can be obtained by subjecting a hydroxyl group in a polyol containing a polyester polyol described later and an isocyanate group in a polyisocyanate to a urethanization reaction under conditions where the hydroxyl group is excessive.

(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 group component.
Examples of the carboxylic acid component include dibasic acids having an aromatic ring such as terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, and phthalic acid anhydride; Examples thereof include aliphatic dibasic acids such as acid, hexahydrophthalic acid anhydride, maleic acid anhydride, and itaconic acid anhydride; or dialkyl esters thereof or mixtures thereof.
Examples of the hydroxyl group include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, butylene glycol, neopentyl glycol, dineopentyl glycol, trimethylolpropane, glycerin, 1,6-hexanediol, and 1 , 4-Butandiol, 1,4-Cyclohexanedimethanol, 3-Methyl-1,5-Pentanediol, 3,3'-Dimethylolheptane, 1,9-Nonandiol, Polyoxyethylene Glycol, Polyoxypropylene Glycol , Polytetramethylene ether glycols, polyether polyols, polycarbonate polyols, polyolefin polyols, acrylic polyols, polyurethane polyols and other diols; or mixtures thereof.
One type of each of the carboxylic acid component and the hydroxyl group component may be used alone, but it is preferable to use two or more types in combination.

The carboxylic acid component preferably contains 5 to 50 mol% of an 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 solvent solubility is enhanced and the obtained polyester polyol solution is lowered in viscosity. As a result, the coatability of the polyurethane adhesive is improved, and a packaging material having a better appearance can be obtained. When it is 50 mol% or less, the glass transition temperature of the polyester polyol can be easily adjusted, and the adhesive strength is further improved. From the same viewpoint, the blending amount of the aliphatic dibasic acid is more preferably 25 to 50 mol% based on the total carboxylic acid component.

The ester bond concentration of the polyester polyol is preferably 9.40 mmol / g to 10.80 mmol / g, more preferably 9.40 to 10.3 mmol / g, and further preferably 9.40 to 9.80 mmol / g.
When the ester bond concentration of the polyester polyol is 9.40 mmol / g or more, the solubility in an ester solvent such as ethyl acetate is excellent, and the amount of isocyanate used for urethanization is not limited, so that good adhesiveness can be exhibited, which is preferable. .. When it is 10.80 mmol / g or less, it is preferable because the increase in viscosity and the decrease in solvent solubility due to the intermolecular interaction due to the ester bond are suppressed.

The ester bond concentration of the polyester polyol can be calculated by the following formula.
Formula: Polyester bond concentration (mmol / g) = molar amount of carboxylic acid component charged x total number of carboxylic acid functional groups / (total charged amount x solid yield) x 1000
Taking the polyester of Synthetic Example 1 as an example,
Isophthalic acid (number of functional groups 2): 148 g = 0.892 mol,
Terephthalic acid (number of functional groups 2): 296 g = 1.783 mol,
Adipic acid (number of functional groups 2): 260 g = 1.780 mol,
Total amount charged 1000.05g, yield 83.9%
The ester bond concentration of polyester 1 is
(0.892 × 2 + 1.783 × 2 + 1.780 × 2) / (1000.5 * 0.839) × 1000 = 10.63
Can be calculated.

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. When the weight average molecular weight is 5,000 or more, the adhesiveness to the substrate is further improved and the processability is excellent. When the weight average molecular weight is 30,000 or less, it is possible to easily prevent the concentration of the hydroxyl group at the terminal of the polyester polyol from becoming excessively low, and the polyurethane resin (a) having a hydroxyl group is obtained by reacting with a polyisocyanate described later. In this case, it is possible to easily prevent the reaction time from being prolonged.

As the polyol constituting the polyurethane resin (a) having a hydroxyl group, a conventionally known polyol can be used in combination with the above polyester polyol. Examples of the polyol that can be used in combination include the hydroxyl group component that can be used for synthesizing the polyester polyol described above, and neoventil glycol and 1,4-butanediol can be preferably used.

(Polyisocyanate)
Examples of the polyisocyanate constituting the polyurethane resin (a) having a hydroxyl group include aliphatic diisocyanates, alicyclic diisocyanates, aromatic diisocyanates, aromatic aliphatic diisocyanates, trifunctional or higher functional polyisocyanate monomers, and the above diisocyanates. Examples include various derivatives to be induced.

Examples of the aliphatic diisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-petitylene diisocyanate, 2,3-butylenediocyanate, and 1,3-butylenedi isocyanate, 2 , 4,4- or 2,2,4-trimethylhexamethylene diisocyanate, 2,6-diisocyanate methyl caproate.

Examples of the alicyclic diisocyanate include 1,4-cyclohexanediisocyanate, 1,3-cyclohexanediisocyanate, 3-isocyanatemethyl-3,5,5-trimethylcyclohexylisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), and methyl. Examples thereof include -2,4-cyclohexanediisocyanate, methyl-2,6-cyclohexanediisocyanate, 1,4-bis (isocyanatemethyl) cyclohexane, and 1,3-bis (isocyanatemethyl) cyclohexane.

Examples of the aromatic diisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalenedi isocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6--. Examples thereof include toluene diisocyanate or a mixture thereof, 4,4'-toluene diisocyanate, dianisidine diisocyanate, and 4,4'-diphenyl ether diisocyanate.

Examples of the aromatic aliphatic diisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω'-diisocyanate-1,4-diethylbenzene, 1,3- or 1,4-bis (1). -Isocyanate-1-methylethyl) benzene or a mixture thereof can be mentioned.

Examples of the trifunctional or higher functional polyisocyanate monomer include triphenylmethane-4,4', 4 "-triisocyanate, 1,3,5-triisocyanatebenzene, 2,4,6-triisocyanate toluene and the like. Triisocyanates; tetraisocyanates such as 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate can be mentioned.

Examples of the various derivatives derived from the diisocyanate include the diisocyanate, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, and the like. Addition with low molecular weight polyols having a molecular weight of less than 200 such as 3,3'-dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol, etc. Body (adduct body); trimeric of the diisocyanate (also referred to as trimmer or nucleolate); biuret body; allophanate body; as well as 2,4,6-oxadiazine trione ring obtained from carbon dioxide gas and the diisocyanate. Polyisocyanate having the above; etc. can be used.

The polyisocyanate constituting the polyurethane resin (a) having a hydroxyl group is preferably an aromatic isocyanate or an alicyclic diisocyanate, and more preferably a tolylene diisocyanate from the viewpoint of moldability and adhesiveness after a high temperature and high humidity test. , 4,4'-diphenyldiisocyanate, 3-isocyanatemethyl-3,5,5-trimethylcyclohexylisocyanate.

The reaction temperature between the polyol and the polyisocyanate when obtaining the polyurethane resin (a) having a hydroxyl group is preferably in the temperature range of 50 ° C to 200 ° C, more preferably 80 to 150 ° C. The molar ratio of isocyanate groups of polyisocyanate to hydroxyl groups in the polyol in the urethanization reaction (number of moles of isocyanate groups / number of moles of hydroxyl groups) is preferably 0.1 to 0.9, more preferably 0. It is 3 to 0.8.

In the present invention, it is important that the ester bond concentration of the polyurethane resin (a) having a hydroxyl group constituting the outer layer side adhesive layer is in the range of 9.20 mmol / g to 10.50 mmol / g, and the ester bond concentration. By controlling the pressure within a predetermined range, the stability of the adhesive solution and the affinity for the substrate due to the ester bond are controlled, and excellent coatability is exhibited. As a result, the obtained packaging material does not deteriorate in adhesive strength between layers even after a high temperature and high humidity / long-term durability test, has excellent moldability, and does not cause appearance defects such as floating between layers. The above effect is remarkably exhibited even when the amount of the adhesive applied is low, that is, the thickness of the outer layer side adhesive layer is small.
When the ester bond concentration is less than 9.20 mmol / g, the solubility in an ester solvent such as ethyl acetate is lowered, and the coatability is lowered. Alternatively, the affinity for the substrate due to the ester bond is lowered, and the adhesive strength is lowered. If it exceeds 10.50 mmol / g, the intermolecular interaction due to the ester bond is enhanced, the viscosity is increased, the solvent solubility is lowered, and the appearance after aging due to the coating defect is deteriorated.
The ester bond concentration of the polyurethane resin (a) having a hydroxyl group is preferably 9.20 to 10.1 mmol / g, more preferably 9.20 to 9.60 mmol / g.

The ester bond concentration of the polyurethane resin (a) having a hydroxyl group can be calculated by the following formula.
Calculation formula: Polyester bond concentration (mmol / g) = Polyester bond concentration of polyester polyol x Ratio of polyester polyol to the total mass of the polyol and polyisocyanate constituting the urethane resin (mass%)
For example, the ester bond concentration of the polyurethane resin (a) having a hydroxyl group shown in Synthesis Example (a) -1 is
Polyester bond concentration = 10.63 x (100/102) = 10.42 mmol / g
Will be.

The urethane bond concentration of the polyurethane resin (a) having a hydroxyl group is preferably in the range of 0.10 to 0.90 mmol / g, more preferably 0.15 to 0.60 mmol / g, and further preferably 0.20. It is ~ 0.40 mmol / g. When it is 0.10 mmol / g or more, an excellent effect of improving compatibility can be obtained and the appearance and adhesiveness are improved, which is preferable. When it is 0.90 mmol / g or less, the urethane bond concentration does not become excessive and the viscosity becomes appropriate, which is preferable because it is excellent in coatability and appearance.
By controlling the urethane bond concentration of the polyurethane resin (a) having a hydroxyl group, the compatibility with the polyisocyanate component (B) which is a curing agent can be improved, the crosslink density is high, and the durability and appearance are improved. An excellent adhesive layer can be formed.

The urethane bond concentration can be calculated using the following formula 1.
Equation 1:
Urethane bond concentration (mmol / g) = [(NCO content of polyisocyanate (% by mass) ÷ 100) × (polyisocyanate (% by mass) with respect to the total (% by mass) of the polyol and polyisocyanate constituting the urethane resin) Blending ratio) ÷ 42 × 1000] + [(number of urethane bonds inside polyisocyanate ÷ polyisocyanate molecular weight) × (blending of polyisocyanate (% by mass) with respect to the total (% by mass) of the polyol and polyisocyanate constituting the urethane resin) Ratio) x 1000]

For example, in the urethane bond concentration of the polyurethane resin (a) having a hydroxyl group shown in Synthesis Example (a) -1, the NCO content of tolylene diisocyanate is 48.2% by mass, and the amount of polyisocyanate added to the polyol is 1 mass. %, Since the number of urethane bonds inside is zero
Urethane bond concentration = 0.482 x (2/102) / 42 x 1000
= 0.23 mmol / g.

The weight average molecular weight of the polyurethane resin (a) having a hydroxyl group is preferably 20,000 to 100,000, more preferably 40,000 to 70,000.
When the weight average molecular weight is 20,000 or more, the extensibility of the resin is further enhanced and the workability is further improved. When the weight average molecular weight is 100,000 or less, it is possible to easily prevent the viscosity of the adhesive solution from becoming excessively high, and the appearance defect is further less likely to occur. Further, by controlling the weight average molecular weight to 40,000 to 70,000, it becomes easier to achieve both the extensibility of the resin and the viscosity of the adhesive solution, and the resin can be used more preferably.

The hydroxyl value of the polyurethane resin (a) having a hydroxyl group is preferably 0.5 to 20 mgKOH / g, more preferably 3 to 10 mgKOH / g. The hydroxyl group is used in the cross-linking reaction with the polyisocyanate component (B) described later, and as the cross-linking reaction proceeds, the adhesive has a higher molecular weight and the heat resistance as a packaging material can be improved. The hydroxyl value can be obtained, for example, by a method according to JIS K 1557-1.

The glass transition temperature of the polyurethane resin (a) having a hydroxyl group is preferably −20 ° C. to 40 ° C., more preferably −10 ° C. to 20 ° C. When the glass transition temperature is −20 ° C. or higher, the cohesive force of the resin is further increased and the adhesiveness is further improved. When the glass transition temperature is 40 ° C. or lower, the affinity for the substrate at the time of laminating is further enhanced, and the adhesive strength after aging is further improved.

The main agent (A) containing the polyurethane adhesive may contain the polyurethane resin (a) having the above-mentioned hydroxyl group, and may further contain the following components as other components. The other components may be added to either the main agent (A) or the curing agent containing the polyisocyanate component (B), and when the main agent (A) and the curing agent containing the polyisocyanate (B) are added. Although it may be added, it is more preferable to add it to the main agent (A).

(solvent)
When the polyurethane adhesive is applied to the base material, the polyurethane adhesive may contain a solvent within a range that does not affect the base material in the drying step in order to adjust the coating liquid to an appropriate viscosity. 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, and ether compounds such as diethyl ether and ethylene glycol dimethyl ether. Examples include compounds, aromatic compounds such as toluene and xylene, aliphatic compounds such as pentane and hexane, halogenated hydrocarbon compounds such as methylene chloride, chlorobenzene and chloroform, alcohols such as ethanol, isopropyl alcohol and normal butanol, and water. Be done. These solvents may be used alone or in combination of two or more. Of these, ethyl acetate is preferably used.

(Reaction accelerator)
Since the polyurethane adhesive promotes the urethanization reaction, it can further contain a reaction accelerator. As the reaction accelerator, metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimarate; 1,8-diazabicyclo (5,4,0) undecene-7,1,5-diazabicyclo (4,3,0) Nonene-5,6-dibutylamino-1,8-diazabicyclo (5,4,0) Undecene-7 and other tertiary amines; reactive tertiary amines such as triethanolamine One or more reaction promoters selected from these groups can be used.

(Silane coupling agent)
The polyurethane adhesive can further contain a silane coupling agent in order to improve the adhesive strength to a metal-based material such as a metal foil. Examples of the silane coupling agent include trialkoxysilane having a vinyl group such as vinyltrimethoxysilane and vinyltriethoxysilane, 3-aminopropyltriethoxysilane, and N- (2-aminoethyl) 3-aminopropyltrimethoxysilane. It has a glycidyl group such as trialkoxysilane, 3-glycidoxypropyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, etc. Examples thereof include trialkoxysilane.

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

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

The epoxy resin is not limited to the following, but is not limited to, for example, 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. -Hexandiol 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, polypropylene glycol diglycidyl Ether is mentioned.
One type of these epoxy resins may be used alone, or two or more types may be used in combination.

Among them, an epoxy resin having a weight average molecular weight of 400 to 10,000 is preferable from the viewpoint of adhesive strength and moisture resistance. The blending amount of the epoxy resin is preferably 5 to 50 parts by mass, and more preferably 10 to 20 parts by mass with respect to 100 parts by mass of the polyurethane resin (a) having a hydroxyl group from the viewpoint of adhesive strength and moisture heat resistance. Is. When the amount is 5 parts by mass or more, the moisture and heat resistance can be improved more effectively, and when the amount is 50 parts by mass or less, the hardness of the adhesive layer can be appropriately softened and sufficient adhesiveness can be easily exhibited.

(Phosphorus acid or its derivative)
The polyurethane adhesive may contain phosphoric acid or a phosphoric acid derivative in order to improve the adhesive strength to a metal-based material such as a metal foil. The phosphoric acid may be any one having at least one free oxygen acid, for example, phosphoric acids such as hypophosphoric acid, phosphoric acid, orthophosphoric acid, hypophosphoric acid, metaphosphoric acid, and pyrophosphoric acid. , Tripolyphosphoric acid, polyphosphoric acid, ultraphosphoric acid and other condensed phosphoric acids. Examples of the phosphoric acid derivative include those in which the above-mentioned phosphoric acid is partially esterified with alcohols while leaving at least one free oxygen acid. Examples of these alcohols include fatty alcohols such as methanol, ethanol, ethylene glycol and glycerin, and aromatic alcohols such as phenol, xylenol, hydroquinone, catechol and fluoroglycinol. One type of phosphoric acid or a derivative thereof may be used alone, or two or more types may be used in combination. The amount of 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 further preferably 0 with respect to 100 parts by mass of the polyurethane resin (a) having a hydroxyl group. It is 0.05 to 1 part by mass.

The polyurethane adhesive may further contain a leveling agent or an antifoaming agent in order to improve the laminated appearance of the packaging material. Examples of the leveling agent include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl group-containing polydimethylsiloxane, polyether ester-modified hydroxyl group-containing polydimethylsiloxane, acrylic copolymer, and methacryl. Examples thereof include system copolymers, polyether-modified polymethylalkylsiloxanes, acrylic acid alkyl ester copolymers, methacrylic acid alkyl ester copolymers, and lecithin.

Examples of the defoaming agent include known ones such as a silicone resin, a silicone solution, and a copolymer of an alkyl vinyl ether, an acrylic acid alkyl ester, and a methacrylic acid alkyl ester.

The polyurethane adhesive may contain additives other than those described above as long as the effects of the present invention are not impaired. Examples of the additive include inorganic fillers such as silica, alumina, mica, talc, aluminum flakes, and glass flakes, layered inorganic compounds, stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, hydrolysis inhibitors, etc.). ), Anti-rust agents, thickeners, plasticizers, antistatic agents, lubricants, anti-blocking agents, colorants, fillers, crystal nucleating agents, catalysts for adjusting the curing reaction and the like.

The main agent (A) is required to have storage stability in which the above-mentioned additive is added to the polyurethane resin (a) having a hydroxyl group, and the solution does not cause turbidity or viscosity change in appearance even at low temperature or high temperature. The turbid incompatible portion in appearance may be the starting point of cracks during molding. Further, when the viscosity changes, it may be difficult to adjust the coating process.

<Polyisocyanate component (B)>
The polyisocyanate component (B) crosslinks with the hydroxyl group in the polyurethane resin (A) having a hydroxyl group, increases the molecular weight of the adhesive layer, and plays a role of improving the internal cohesive force that develops energy elasticity. Further, 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 enhanced by causing a self-crosslinking reaction during curing.
Normally, the urethane bond or urea bond generated by the cross-linking reaction has a hydrogen bond and has a high polarity, so that the compatibility with the resin is inferior, and the appearance may be poor or a defect may occur during molding. By using the polyurethane resin (a) having a predetermined hydroxyl group in combination with the polyisocyanate component (B), it is possible to form an adhesive layer having excellent compatibility, good appearance and toughness, and is used for power storage devices. Good physical properties can be obtained as a packaging material.

Further, the polyisocyanate component (B) has a function of improving the interaction with the surface of the base material described later, and in particular, a base material that has been subjected to physical treatment such as corona discharge treatment or chemical treatment such as acid modification is used. If so, the reactive functional group in the polyisocyanate component (B) and the hydroxyl group on the surface of the base material chemically react to develop a strong interaction between the outer layer side adhesive layer and the base material. Can be done.
In this way, by using the polyisocyanate component (B), it is possible to form a strong outer layer side adhesive layer, and the adhesive layer suppresses the expansion and contraction movement of the base material due to a sudden environmental change, and the adhesive layer adheres. It is possible to maintain a high level of strength.

As the polyisocyanate compound (B), those listed in the section of (polyisocyanate) constituting the polyurethane resin (a) having a hydroxyl group described above can be used, and one type may be used alone or two types may be used. The above may be used together.

Among them, the polyisocyanate compound (B) is preferably a nurate form of diisocyanate, an adduct form in which trimethylolpropane is added to diisocyanate, a biuret type, and a prepolymer having an isocyanate residue (a low polymer obtained from diisocyanate and polyol). A uretdione compound having an isocyanate residue, an allophanate compound, or a complex thereof.
In electronic device applications, aromatic isocyanates or derivatives thereof are preferable from the viewpoint of achieving both excellent heat resistance and high cohesive force and processability.

Further, it is preferable that the polyisocyanate constituting the polyurethane resin (a) having a hydroxyl group and the polyisocyanate component (B) are the same, because the compatibility is further enhanced. That is, the polyisocyanate component (B) more preferably contains a tolylene diisocyanate or an adduct body in which trimethylolpropane is added to the tolylene diisocyanate.

The content of the polyisocyanate component (B) is preferably 10 to 40% by mass, more preferably 20 to 30% by mass, based on the solid content mass of the polyurethane resin (a) having a hydroxyl group. When the polyisocyanate component (B) is 10% by mass or more, the molecular weight of the adhesive layer can be efficiently increased. As a result, the internal cohesive force is improved and high adhesive strength can be easily obtained. When it is 40% by mass or less, the amount of highly polar urethane bonds and urea bonds generated by the crosslinking reaction is appropriately controlled, and it is possible to easily suppress the deterioration of appearance and the occurrence of defects during deformation due to processing.

<Manufacturing of packaging materials for power storage devices>
The method for producing the packaging material for a power storage device of the present invention is not particularly limited, and the packaging material can be produced by a known method.
For example, the outer layer side resin film layer (1) and the metal foil layer (3) are laminated by using the polyurethane adhesive forming the outer layer side adhesive layer (2), and the outer layer side resin film layer (1) is laminated. ) / Outer layer side adhesive layer (2) / Metal foil layer (3) After obtaining an intermediate laminate, heat seal the metal foil layer (3) surface of the intermediate laminate using the inner layer side adhesive. The layer (5) can be laminated and manufactured (hereinafter, referred to as manufacturing method 1).
Alternatively, the metal foil layer (3) and the heat seal layer (5) are laminated using the inner layer side adhesive to form the metal foil layer (3) / inner layer side adhesive layer (4) / heat seal layer (5). After obtaining the intermediate laminate having the above-mentioned structure, the metal foil layer (3) and the outer layer side resin film layer (1) of the intermediate laminate can be laminated and manufactured by using the above-mentioned polyurethane adhesive. (Hereinafter referred to as manufacturing method 2).

In the case of the production method 1, the above-mentioned polyurethane adhesive is applied to one side of the base material of either the outer layer side resin film layer (1) or the metal foil layer (3), the solvent is volatilized, and then uncured. It is preferable that the other base material is superposed on the outer layer side adhesive layer under heating and pressurization, and then aged at room temperature (for example, 25 ° C.) to less than 100 ° C. to cure the outer layer side adhesive layer. If the aging temperature is less than 100 ° C., heat shrinkage of the outer layer side resin film layer (1) does not occur, so that the elongation at break and the stress at break, which affect the molding, are lowered, and the molding productivity is lowered due to the film curl. It can be easily prevented.
The amount of the outer layer side adhesive applied after drying is preferably about 1 to 15 g / m ² .

Further, the packaging material for a power storage device of the present invention has excellent adhesive strength and moldability after a high temperature and high humidity / long-term durability test even if the adhesive is a thin film, and causes poor appearance such as floating between layers. not. Specifically, the packaging material for a power storage device of the present invention has a high temperature, high humidity and long-term even if the coating amount of the adhesive after drying is 3 g / m ² or less, and the coating amount is further reduced to 2 g / m ² or less. It is excellent in adhesive strength after durability test, moldability, and suppression of floating between layers, and it is possible to achieve both thinning of adhesive and moldability, adhesive strength between layers after high temperature, high humidity and long-term durability test. It exerts an excellent effect.

Similarly, in the case of the manufacturing method 2, the above-mentioned 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.

As a method for forming the outer layer side adhesive layer, a comma coater, a dry laminator, a roll knife 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, or the like is used. The method can be mentioned.

<Outer layer side resin film layer (1)>
The outer layer side resin film layer (1) is not particularly limited, but it is preferable to use a stretched film made of polyamide or polyester. Further, it may be colored with a pigment such as carbon black or titanium oxide. Further, 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 scratch prevention and electrolytic solution resistance, and is coated with printing ink for the purpose of designability. You may. Further, the outer layer side resin film layer (1) may have two or more films laminated in advance. The thickness of the outer layer side resin film layer (1) is not particularly limited, but is preferably 12 to 100 μm.

<Metal leaf 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 treated with phosphoric acid chromate, chromic acid chromate treatment, trivalent chromium treatment, zinc phosphate treatment, zirconium phosphate treatment, acid value zirconium treatment, titanium phosphate treatment, hydrofluoric acid treatment, It is preferable that a known antiseptic treatment such as cerium treatment or hydrotalcite treatment is applied. The antiseptic treatment can suppress the corrosion deterioration of the metal foil surface due to the electrolytic solution of the battery. Further, it is preferable to bake a known organic primer such as a phenol resin, an amide resin, an acrylic resin, polyvinyl alcohol, or a coupling agent onto a metal at a high temperature of about 200 ° C. to treat the surface of the antiseptic treatment. By applying the organic primer treatment, the metal foil and the adhesive can be adhered more firmly, and the floating between the metal foil and the adhesive can be further suppressed.

<Heat seal layer (5)>
The heat-sealed layer (5) is not particularly limited, but is preferably unstretched from at least one thermoplastic resin selected from the group consisting of polyethylene, polypropylene, olefin-based copolymers, acid variants thereof and ionomers. It is a film. The thickness of the heat seal layer is not particularly limited, but is preferably 20 to 150 μm.

<Inner layer side adhesive layer (4)>
The adhesive forming the inner layer side adhesive layer (4) is not particularly limited, but it is preferable that the adhesive strength between the metal foil layer (3) and the heat seal layer (5) is not lowered by the electrolytic solution of the power storage device, which is known. Adhesives can be used.
For the inner layer side adhesive layer (4), for example, an adhesive combining a polyolefin resin and polyisocyanate or an adhesive combining a polyol and polyisocyanate is applied to the metal foil layer (3) using a gravure coater or the like. It can be formed by drying the solvent, superimposing the heat seal layer (5) on the adhesive layer under heating and pressurization, and then aging at room temperature or heating.
Alternatively, an adhesive such as acid-modified polypropylene is melt-extruded onto the metal foil layer (3) with a T-die extruder to form an adhesive layer, and the heat seal layer (5) is laminated on the adhesive layer to form a metal. The inner layer side adhesive layer (4) can be formed by laminating the foil layer (3) and the heat seal layer (5).
When both the outer layer side adhesive layer (2) and the inner layer side adhesive layer (4) require aging, the outer layer side resin film layer (1), the uncured outer layer side adhesive layer, and the metal foil layer. (3) The uncured inner layer side adhesive layer and the heat seal layer (5) may be collectively aged after obtaining a laminated body having a structure in which the uncured inner layer side adhesive layer and the heat seal layer (5) are laminated from the outside in this order.

<Container for power storage device>
The container for a power storage device of the present invention is molded by using the packaging material for a power storage device of the present invention so that the outer layer side resin film layer (1) forms a convex surface and the heat seal layer (5) forms a concave surface. Obtainable. The "concave surface" as used in the present invention is a surface having a recess that can accommodate the electrolytic solution when the packaging material for a power storage device in a flat state is molded into a tray shape as shown in FIG. That is, the "convex surface" in the present invention means the self-rear surface of the surface having the recess.

<Power storage device>
The power storage device of the present invention is made by using the storage device container, for example, a secondary battery such as a lithium ion battery, a nickel hydrogen battery, and a lead storage battery, and an electric chemical capacitor such as an electric double layer capacitor. Can be mentioned.
A general storage device includes a battery element including an electrode, a lead extending from the electrode, and a container for accommodating the battery. In the energy storage device of the present invention, the container for the energy storage device is used for the container for accommodating the battery element. The container to be stored is formed from the packaging material for a power storage device so that the heat seal layer (5) is on the inside, and the heat seal layers (5) of the two packaging materials are overlapped and overlapped with each other facing each other. It may be obtained by heat-sealing the peripheral edge portion of the packaging material, or one packaging material may be folded back and superposed, and the peripheral edge portion of the packaging material may be heat-sealed in the same manner.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. “Parts” and “%” in Examples and Comparative Examples mean “parts by mass” and “% by mass” unless otherwise specified.

<Measurement of acid value (AV)>
About 1 g of a sample (polyester polyol solution) was precisely weighed in an Erlenmeyer flask with a stopper, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixed solution was added and dissolved. Phenolphthalein test solution was added to this as an indicator and held for 30 seconds. Then, the solution was titrated with a 0.1N alcoholic potassium hydroxide solution until the solution turned pink, and the acid value (mgKOH / g) was determined by the following formula.
Acid value (mgKOH / g) = (5.611 × a × F) / S
However, S: sample collection amount (g)
a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml)
F: Titer of 0.1N alcoholic potassium hydroxide solution

<Measurement of hydroxyl value (OHV)>
Precisely weigh about 1 g of a sample (polyester polyol, hydroxyl group-containing urethane resin (a), etc.) in an Erlenmeyer flask with a stopper, and add 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2/1) mixture to dissolve it. bottom. Further, exactly 5 ml of an acetylating agent (a solution in which 25 g of acetic anhydride was dissolved in pyridine to make a volume of 100 ml) was added, and the mixture was stirred for about 1 hour. Phenolphthalein test solution was added to this as an indicator and lasted for 30 seconds. Then, the solution was titrated with a 0.5N alcoholic potassium hydroxide solution until the solution turned pink, and the hydroxyl value (mgKOH / g) was determined by the following formula.
Hydroxy group value (mgKOH / g) = [{(ba) × F × 28.05} / S] + D
However, S: sample collection amount (g)
a: Consumption of 0.5N alcoholic potassium hydroxide solution (ml)
b: Consumption (ml) of 0.5N alcoholic potassium hydroxide solution in the blank experiment
F: Titer of 0.5N alcoholic potassium hydroxide solution
D: Acid value (mgKOH / g)

<Measurement of number average molecular weight (Mn), weight average molecular weight (Mw), molecular weight distribution (Mw / Mn)>
For the average molecular weight and molecular weight distribution, use Shodex (registered trademark) (manufactured by Showa Denko KK), columns: KF-805L, KF-803L, and KF-802 (trade names, all manufactured by Showa Denko KK). The values measured in terms of standard polystyrene were used, where the column temperature was 40 ° C., THF was used as the eluent, the flow velocity was 0.2 ml / min, the detection was RI, and the sample concentration was 0.02% by mass.

<Glass transition temperature (Tg)>
The glass transition temperature was measured by DSC (Differential Scanning Calorimetry). Specifically, about 2 mg of the compound to be measured is weighed on an aluminum pan, the aluminum pan is set in the DSC measurement holder, and the heat absorption peak of the chart obtained under the heating condition of 5 ° C./min is read. The peak temperature at that time was taken as the glass transition temperature.

<Synthesis of polyester polyol>
(Polyester 1)
148 parts of isophthalic acid, 296 parts of terephthalic acid, 260 parts of adipic acid, 250 parts of ethylene glycol and 46 parts of neopentyl glycol were charged, and an esterification reaction was carried out at 170 to 230 ° C. for 10 hours. After distilling a predetermined amount of water, 0.05 part of tetraisobutyl titanate was added, the pressure was gradually reduced, and a transesterification reaction was carried out at 1.3 to 2.6 hPa and 230 to 250 ° C. for 3 hours to obtain a number average molecular weight (Mn). ) 9,200, weight average molecular weight (Mw) 19,000, molecular weight distribution (Mw / Mn) 2.07, hydroxyl value 14.0 mgKOH / g, acid value 0.2 mgKOH / g, glass transition temperature 2 ° C. polyester polyol Polyester 1 was obtained with a molecular weight of 83.9%. The ester bond concentration of polyester 1 was 10.63 mmol / g.
Assuming that the excess hydroxyl group component is distilled off almost evenly and the total of the carboxylic acid component and the hydroxyl group component is 200 mol%, the composition of the obtained polyester 1 is isophthalic acid: terephthalic acid: adipic acid: ethylene. Glycol: Neopentyl glycol = 20:40:40:90:10 (mol%).

(Polyester 2-13)
The carboxylic acid component and the hydroxyl group component are reacted in the same manner as in Polyester 1 so that the amount of the carboxylic acid component and the hydroxyl group component charged in the obtained polyester polyol is as shown in Table 1, and the polyesters 2 to 13 are reacted. Got

The abbreviations in Table 1 are as follows.
PA: Orthophthalic acid IPA: Isophthalic acid TPA: Terephthalic acid AdA: Adipic acid EG: Ethylene glycol NPG: Neopentyl glycol 1,6-HD: 1,6-Hexanediol MPO: 2-Methyl-1,3-propanediol DEG : Diethylene glycol

<Synthesis of Hydroxyl Group-Containing Polyurethane Resin (a)>
(Urethane (a) -1)
100 parts of the obtained polyester 1 and 40 parts of ethyl acetate were placed in a 1-liter 4-neck flask, the temperature was raised to 80 ° C., and the mixture was stirred until the solution became uniform. To this, 2.0 parts of tolylene diisocyanate and 0.15 parts of dibutyl tin dilaurate were added, and the reaction was carried out for 4 hours. After completion of the reaction, 113 parts of ethyl acetate was added, ester bond concentration 10.42 mmol / g, urethane bond concentration 0.23 mmol / g, Mn23,500, Mw56,100, Tg4 ° C., hydroxyl value 7.9 mgKOH / g, non-volatile. A urethane (a) -1 solution, which is a polyurethane resin having a hydroxyl group having a hydroxyl group of 40%, was obtained.

(Urethane (a) -2 to (a) -15, comparison (a) -1 to (a) -4)
Urethanes (a) -2 to (a), which are polyurethane resins (a) having a hydroxyl group by reacting a polyol with a polyisocyanate in the same manner as urethane (a) -1, except that the blending amount is changed to that shown in Table 2. a) -15 and comparisons (a) -1 to (a) -4 were obtained.

The abbreviations in Table 2 are as follows.
NPG: Neopentyl glycol TDI: Tolylene diisocyanate (Coronate T-80 (trade name), manufactured by Tosoh Corporation, NCO content 48.2%)
MDI: 4,4'-diphenylmethane diisocyanate (Millionate MT (trade name), manufactured by Tosoh Corporation, NCO content 33.5%)
HDI: Hexamethylene diisocyanate (Death Module (registered trademark) H (trade name), manufactured by Covestro, NCO content 49.9%)
IPDI: Isophorone diisocyanate (Death Module I (trade name), manufactured by Covestro, NCO content 37.7%)
H6XDI: 1,3-bis (isocyanatomethyl) cyclohexane (Takenate 600 (trade name) manufactured by Mitsui Chemicals, Inc., NCO content 43.2%)

<Manufacturing of packaging materials for power storage devices>
[Example 1]
250 parts of urethane (a) -1 solution (100 parts in terms of solids) and 1.0 part of glycidpropyltrimethoxysilane as an additive were added, and after stirring for 30 minutes, diluted with ethyl acetate to have a solid content concentration of 40. % Main agent (A) was obtained. 40 parts (30 parts in terms of solids) of coronate L (trade name, manufactured by Tosoh Corporation, solid content concentration 75%, NCO content 13.2%) was charged therein as the polyisocyanate component (B), and the mixture was made of ethyl acetate. Diluted to prepare an adhesive solution having a solid content concentration of 30%.
Using a dry laminator, the above adhesive solution for the outer layer side adhesive layer (2) is applied to one surface of an aluminum foil having a thickness of 40 μm, the solvent is volatilized, and then a stretched polyamide film having a thickness of 30 μm is laminated. An intermediate laminate was obtained. The amount of the adhesive applied after drying was 2 g / m ² and 4 g / m ² .
Next, using a dry laminator, an adhesive for the inner layer side adhesive layer described later was applied to the other surface of the aluminum foil of the obtained intermediate laminate, the solvent was volatilized, and then unstretched polypropylene having a thickness of 30 μm was applied. The films were laminated to obtain a laminated body. The amount of the adhesive applied after drying was 4 g / m ² .
Next, aging was performed at 60 ° C. and 30% RH (relative humidity) and 60 ° C. and 90% RH for 7 days, respectively, to cure the adhesive layers on the outer layer side and the inner layer side, and the outer layer side resin film layer (1). A packaging material for a battery having a structure of / outer layer side adhesive layer (2) / metal foil layer (3) / inner layer side adhesive layer (4) / heat seal layer (5) was obtained.

(Adhesive for inner layer side adhesive layer)
AD-502 (trade name, manufactured by Toyo Morton Co., Ltd., polyester polyol) is used as the main agent, and CAT-10L (trade name, manufactured by Toyo Morton Co., Ltd., isocyanate-based curing agent) is used as the curing agent. The mixture was blended so as to have a solid content concentration of 100/10 (mass ratio) and adjusted to a solid content concentration of 30% with ethyl acetate, and used as an adhesive for the inner layer side adhesive layer.

[Examples 2 to 17, Comparative Examples 1 to 5]
The same operation as in Example 1 was performed except that the blending amount (part) in Table 3 was changed, and a packaging material for a battery was obtained.

<Evaluation of packaging materials for power storage devices>
The obtained packaging materials for power storage devices were evaluated as follows. The results are shown in Table 3.

[Evaluation of storage stability of main agent A]
The main agent (A) having a solid content concentration of 40% was stored at 5 ° C. for 4 weeks, and the appearance and viscosity change after standing at 23 ° C. for 4 hours were evaluated according to the following criteria. The viscosity was measured using a B-type viscometer under the condition of 25 ° C.
A: No change in appearance or viscosity is seen before and after storage at 5 ° C (good).
B: The appearance becomes turbid before and after storage at 5 ° C, but the original appearance is restored by heating at 60 ° C for 2 hours. Moreover, the increase in viscosity is less than 20% (usable).
C: The appearance becomes turbid before and after storage at 5 ° C, and it does not return to its original state even when heated at 60 ° C for 2 hours. Or, the viscosity increases by 20% or more before and after storage at 5 ° C (cannot be used).

[Appearance evaluation of packaging materials]
The appearance of the battery packaging material after drying of the outer layer side adhesive was 4 g / m ² and the aging conditions were 60 ° C. for 30% RH for 7 days and 60 ° C. for 90% RH for 7 days. Evaluated by criteria.
A: No whitening or foaming (good)
B: There is some whitening, but no foaming is seen (usable)
C: Whitening or foaming is seen (cannot be used)

[Laminate strength (before wet heat test)]
The amount of the outer layer side adhesive applied after drying was 2 g / m ² and 4 g / m ² , and the packaging material for batteries with an aging condition of 60 ° C. and 30% RH for 7 days was cut into a size of 200 mm × 15 mm and pulled. A T-type peeling test was performed using a testing machine, and the peeling strength (N / 15 mm width) between the stretched polyamide film and the aluminum foil was measured. The measurement was carried out in an environment of 20 ° C. and 65% RH at a load rate of 300 mm / min, and was evaluated according to the following criteria based on the average value of five test pieces.
S: Average peel strength is 7N or more (very good)
A: The average peel strength is 4N or more and less than 7N (good).
B: The average value of peel strength is 2N or more and less than 4N (usable)
C: Average peel strength is less than 2N (cannot be used)

[Laminate strength (after wet heat test)]
The amount of the outer layer side adhesive applied after drying is 2 g / m ² and 4 g / m ² , and the aging conditions are 60 ° C. and 30% RH for 7 days. After leaving it in the container for 168 hours, it was taken out from the constant temperature and humidity chamber, and after standing for 2 hours in an environment of 20 ° C. and 65% RH, the same behavior as before the wet heat test was performed, and the laminate strength was evaluated based on the same standard. bottom.

[Evaluation of moldability]
The coating amount of the outer layer side adhesive after drying was 2 g / m ² , and the battery packaging material having an aging condition of 60 ° C. and 30% RH for 7 days was cut into a size of 80 × 80 mm to obtain a blank. The stretched polyamide film is placed on the outside of the blank, and a straight mold with a free molding height is used to perform one-stage molding, and the maximum molding height does not cause breakage of the aluminum foil or floating between layers. Therefore, the moldability was evaluated according to the following criteria.
The punch shape of the mold used was a square with a side of 30 mm, the corner R was 2 mm, and the punch shoulder R was 1 mm. The hole shoulder R is 1 mm, the clearance between the punch and the die hole is 2 mm on one side, and the clearance causes an inclination according to the molding height.
S: Maximum molding height is 6 mm or more (very good)
A: The maximum molding height is 4 mm or more and less than 6 mm (good).
B: The maximum molding height is 2 mm or more and less than 4 mm (usable).
C: Maximum molding height is less than 2 mm (cannot be used)

[Moisture and heat resistance of molded products]
The coating amount of the outer layer side adhesive after drying was 2 g / m ² , and the battery packaging material having an aging condition of 60 ° C. and 30% RH for 7 days was cut into a size of 80 × 80 mm to obtain a blank. The stretched polyamide film was placed on the outside of the blank, and a straight mold with a free molding height was used to overhang the blank at a molding height of 3 mm and perform one-stage molding to obtain a molded product.
Next, the molded product was placed in a constant temperature and humidity chamber under an atmosphere of 85 ° C. and 85% RH, allowed to stand for 168 hours, then taken out from the constant temperature and humidity chamber, visually checked for floating, and based on the following criteria. evaluated.
The punch shape of the mold used was a square with a side of 30 mm, the corner R was 2 mm, and the punch shoulder R was 1 mm. The hole shoulder R is 1 mm.
A: No floating (good)
B: Floating occurs on one of the four sides (usable)
C: Floating occurs on 2 or more of the 4 sides (cannot be used)

[Heat resistance of molded products]
Except for changing the standing condition from 168 hours at 85 ° C. 85% RH to 120 ° C. 168 hours, visually confirm whether or not floating has occurred in the same manner as in the evaluation of moisture resistance and heat resistance of the molded product. Evaluated according to the criteria of.
A: No floating (good)
B: Floating occurs on one of the four sides (usable)
C: Floating occurs on 2 or more of the 4 sides (cannot be used)

The abbreviations in Table 3 are as follows.
SC-1: Glycydopropyltrimethoxysilane 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: Dibutyltin dilaurate NCO-1: Trimethylolpropane adduct of tolylene diisocyanate (trade name: Coronate L, manufactured by Tosoh Corporation, non-volatile content concentration 75%, NCO content 13.2%)

From the results in Table 3, the packaging material using the hydroxyl group-containing polyurethane resin (a) having a predetermined ester bond concentration as the main agent for forming the outer layer side adhesive layer has good storage stability of the main agent and is high. It showed adhesiveness and moldability. In particular, even if the coating amount of the outer layer side adhesive layer is a thin film of 2 g / m ² , the laminating strength and moldability of the packaging material are excellent. Furthermore, when the urethane bond concentration is within a predetermined range, it has excellent compatibility with polyisocyanate, which is a curing agent, and even when cured under high humidity conditions such as 60 ° C. and 90% RH, appearance defects such as foaming and cloudiness are suppressed. Was done.
In particular, in Example 10, since the ester bond concentration, urethane bond concentration, weight average molecular weight, and glass transition temperature of the polyurethane resin (a) having a hydroxyl group are appropriate, the storage stability of the main agent (A) and the outer layer side backing are appropriate. The material layer was excellent in laminating strength and workability.

On the other hand, Comparative Example 1 corresponds to the example of International Publication No. 2018/11080, but the ester bond concentration is low, the storage stability as a main agent is low, it is difficult to apply, and the laminate strength is high. It has declined.
Comparative Example 2 corresponds to an example of JP-A-2016-196580, but the ester bond concentration is low, the cohesive force is insufficient, and poor moldability occurs when the thin film has a coating amount of 2 g / m ² . bottom.

Comparative Examples 3 and 4 are examples in which the ester bond concentration of the polyurethane resin (a) having a hydroxyl group is low, but poor appearance occurred when the polyurethane resin (a) was cured under a high humidity condition such as 60 ° C. and 90% RH. Due to this effect, the laminating strength and moldability after the moist heat test decreased.

Comparative Example 5 is an example in which a non-urethaneized polyester polyol is used as the main resin, but the compatibility with the polyisocyanate (B) is lowered, and the polyester polyol is cured under high humidity conditions such as 60 ° C. and 90% RH. The appearance was poor and the laminate strength was reduced.

(1): Outer layer side resin film layer (2): Outer layer side adhesive layer (3): Metal leaf layer (4): Inner layer side adhesive layer (5): Heat seal layer

Claims (8)

At least, the outer layer side resin film layer (1), 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 from the outside in this order. It is a packaging material for power storage devices with the above configuration.
The outer layer side adhesive layer (2) is formed of a polyurethane adhesive containing a main agent (A) containing a polyurethane resin (a) having a hydroxyl group and a curing agent containing a polyisocyanate component (B). can be,
The polyurethane resin (a) having a hydroxyl group is a reaction product of a polyester polyol and a polyisocyanate, and is a packaging material for a power storage device having an ester bond concentration of 9.20 to 10.50 mmol / g. .. The packaging material for a power storage device according to claim 1, wherein the polyurethane resin (a) having a hydroxyl group has a urethane bond concentration of 0.10 to 0.90 mmol / g. The packaging material for a power storage device according to claim 1 or 2, wherein the polyurethane resin (a) having a hydroxyl group has a hydroxyl value of 0.5 to 20 mgKOH / g. The storage storage 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 5,000 to 30,000 and a polyisocyanate. Packaging material for devices. The packaging material for a power storage device according to any one of claims 1 to 4, wherein the polyurethane resin (a) having a hydroxyl group has a weight average molecular weight of 40,000 to 70,000. The packaging material for a power storage device according to any one of claims 1 to 5, wherein the polyurethane resin (a) having a hydroxyl group has a glass transition temperature of −10 ° C. to 20 ° C. A container for a power storage device formed of the packaging material for a power storage device according to any one of claims 1 to 6 , wherein the outer layer side resin film layer (1) forms a convex surface, and the heat seal layer (5). Is a container for power storage devices that constitutes a concave surface. A power storage device including the container for the power storage device according to claim 7 .

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