JP7416313B1 - Adhesives for packaging materials for power storage devices, packaging materials for power storage devices, containers for power storage devices, and power storage devices - Google Patents

Abstract

[Problem] Even when the amount of adhesive applied is small and the curing time is shortened, high adhesiveness and flexibility can be achieved, and it is possible to achieve both excellent moldability and long-term durability under high temperature and high humidity conditions. Provided is an adhesive for a packaging material for a power storage device, and a packaging material for a power storage device, a container for a power storage device, and a power storage device that use the adhesive and have excellent moldability and long-term durability. [Solution] Contains a polyisocyanate (A) and a polyol (B), the polyol (B) contains a polyester polyol (b1), and the polyol (B) has a mass of 20% based on the mass of the polyisocyanate (A). The problem is solved by an adhesive for packaging materials for electricity storage devices, which contains a partial structure represented by the following general formula (1) in an amount of 0.5 to 12.0% by mass based on the solid mass of the adhesive. (-C-CR-O-)n(1) [wherein R represents a hydrogen atom or a methyl group, and n represents an integer of 2 to 20. ] [Selection diagram] Figure 1

Description

The present invention relates to an adhesive for packaging materials for power storage devices for forming containers for power storage devices such as lithium ion batteries, and an energy storage device packaging material that has a good appearance and excellent adhesive strength and moldability. related to adhesives.

BACKGROUND OF THE INVENTION Due to the rapid growth of electronic devices such as mobile phones and portable personal computers, the demand for power storage devices such as secondary batteries such as lithium ion batteries and nickel metal hydride batteries and electrochemical 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. Traditionally, metal cans have been used as exterior bodies for lithium-ion batteries, but from the viewpoint of weight reduction and productivity, packaging materials laminated with plastic films, metal foils, etc. are becoming mainstream.

In the field of packaging materials for power storage devices, for example, Patent Document 1 describes a polyol-modified polyisocyanate, which is a compound of an aromatic isocyanate having a trifunctional or more functional isocyanate group in its molecular structure, and a polyester polyol, and a polyester polyol. It is disclosed that a laminating adhesive composition for a battery packaging material containing the above has excellent adhesiveness and heat resistance, and can shorten the curing period.

Japanese Patent Application Publication No. 2018-110086

In recent years, with the expansion of applications such as in-vehicle and home power storage, there is a demand for larger capacity secondary batteries, and packaging materials for power storage devices are required to have good moldability. On the other hand, there is a demand for further weight reduction in automotive applications, and even if the amount of adhesive applied is reduced, the adhesive strength between the layers of packaging materials such as plastic films and metal foils is still low after molding and long-term durability tests. There is a need for a packaging material that can be maintained even under normal conditions and has no abnormal appearance. Additionally, as the amount of adhesive applied decreases, it is also desired to further shorten the curing period and improve productivity.

However, since the adhesive described in Patent Document 1 does not contain the partial structure represented by the general formula (1), the urethanization reaction does not proceed quickly. Therefore, in harsh usage environments that require a reduction in the amount of adhesive applied and a shortening of the curing period in recent years, it takes time for adhesive properties to develop, and the adhesive strength after molding and long-term There is a problem that adhesive strength decreases after the durability test.

Therefore, the purpose of the present invention is to achieve high adhesiveness and flexibility even when the amount of adhesive applied is small and the curing time is shortened, and to achieve excellent moldability and long-term durability under high temperature and high humidity conditions. An object of the present invention is to provide an adhesive for a packaging material for a power storage device that can achieve both of the above, and a packaging material for a power storage device, a container for a power storage device, and a power storage device using the adhesive and having excellent moldability and long-term durability.

As a result of intensive studies to solve the above problems, it was discovered that the above problems could be solved by the embodiments shown below, and the present invention was completed.

<1> That is, the present invention is an adhesive for an electricity storage device packaging material containing a polyisocyanate (A) and a polyol (B), wherein the polyol (B) contains a polyester polyol (b1), and the polyol (B) is contained in an amount of 20 to 60% by mass based on the mass of polyisocyanate (A), and the partial structure represented by the following general formula (1) is contained in an amount of 0.5 to 12% based on the solid mass of the adhesive. The present invention relates to an adhesive for packaging materials for electricity storage devices containing 0% by mass.
General formula (1)
[In general formula (1), R represents a hydrogen atom or a methyl group, and n represents an integer of 2 to 20. ]

<2> The present invention relates to the adhesive for an electricity storage device packaging material according to <1>, wherein the polyisocyanate (A) contains a reaction product of a polyisocyanate and a polyol containing a polyester polyol (a2). .

<3> The present invention is characterized in that the polyisocyanate (A) includes a reaction product of a polyisocyanate containing an aromatic polyisocyanate adduct (a1) and a polyol containing a polyester polyol (a2). ] or <2>.

<4> In the present invention, the polyhydric alcohol that is a component of the polyester polyol (a2) contains 5 to 30% of the polyhydric alcohol having a partial structure represented by the general formula (1) in 100 mol% of the polyhydric alcohol. It relates to the adhesive for electricity storage device packaging material according to <2> or <3>, which contains mol %.

<5> The present invention provides <1> to <3, wherein the polyol (B) further contains a hydroxyl group-containing epoxy resin (b2) in a range of 5 to 50% by mass based on the mass of the polyol (B). >Related to the adhesive for a packaging material for an electricity storage device according to any one of the items.

<6> The present invention relates to the adhesive for an electricity storage device packaging material according to <5>, wherein the hydroxyl group-containing epoxy resin (b2) is a bisphenol A epoxy resin.

<7> The present invention is an electricity storage device packaging material having a structure in which at least an outer resin film layer, an outer adhesive layer, a metal foil layer, an inner adhesive layer, and a heat seal layer are laminated in this order. The present invention relates to an electricity storage device packaging material, wherein the outer adhesive layer is a cured product of the adhesive for electricity storage device packaging material according to any one of <1> to <6>.

<8> The present invention provides a container for a power storage device formed from the power storage device packaging material according to <7>, wherein the outer resin film layer forms a convex surface and the heat seal layer forms a concave surface. The present invention relates to a container for an electricity storage device.

<9> The present invention relates to an electricity storage device comprising the electricity storage device container according to <8>.

With the present invention, even when the amount of adhesive applied is small and the curing time is shortened, high adhesion and flexibility are achieved, and both excellent moldability and long-term durability under high temperature and high humidity conditions are achieved. It is possible to provide an adhesive for a packaging material for a power storage device that can be used, and a packaging material for a power storage device, a container for a power storage device, and a power storage device that use the adhesive and have excellent moldability and long-term durability.

FIG. 1 is a schematic cross-sectional view of a packaging material for an electricity storage device of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic perspective view of one embodiment (tray-like) of a container for an electricity storage device of the present invention.

<Adhesive for power storage device packaging materials>
The adhesive for packaging materials for power storage devices (hereinafter also referred to as adhesive) of the present invention is an adhesive containing polyisocyanate (A) and polyol (B), wherein polyol (B) is polyester polyol (b1 ), contains 20 to 60% by mass of polyol (B) based on the mass of polyisocyanate (A), and has a partial structure represented by the above general formula (1) of 0% based on the solid mass of the adhesive. It is characterized by containing .5 to 12.0% by mass.

First, by including 0.5 to 12.0% by mass of the highly hydrophilic partial structure represented by the above general formula (1), the affinity with water increases, and the reaction between polyisocyanate (A) and water is increased. promoted. This reaction forms urea bonds with high cohesive force, and since the self-crosslinking reaction progresses during curing and the cohesive force improves, high adhesiveness can be exhibited even with a small coating amount and a short curing time. Furthermore, since the above partial structure is a flexible skeleton, by having a predetermined amount of such flexible partial structures, excellent moldability can be exhibited. The content of the partial structure is preferably 5.0 to 10.0% by mass. When it is 5.0% by mass or more, curing progresses easily even with a short curing time, and when it is 10% by mass or less, it has excellent moist heat resistance.
The partial structure of general formula (1) may be contained in at least one of the polyisocyanate (A) and the polyol (B), or may be contained in both. From the viewpoint of improving the compatibility between polyisocyanate (A) and polyol (B) and further improving the appearance, both polyisocyanate (A) and polyol (B) contain the partial structure of general formula (1). is preferred.
R in general formula (1) is preferably a hydrogen atom. When R is a hydrogen atom, the affinity with water is further increased, which is preferable from the viewpoint of shortening the curing period, and the cohesive force of the adhesive layer is increased, resulting in improved adhesiveness and moldability.

Furthermore, it is important that the adhesive of the present invention contains 20 to 60% by mass of the polyol (B) containing the polyester polyol (b1), more preferably 25 to 45% by mass based on the mass of the polyisocyanate (A). It is in the range of % by mass. When the amount is less than 20% by mass, the cured film becomes excessively rigid and has insufficient adhesion and followability to the base material, making it impossible to achieve both adhesive strength and moldability. If it exceeds 60% by mass, the cohesive force of the adhesive decreases, and the amount of hydroxyl groups in the adhesive increases and the isocyanate group decreases, resulting in a decrease in affinity with the base material and insufficient adhesive strength and moist heat resistance. do. In addition, since the polyol (B) contains the polyester polyol (b1), the adhesion with the base material is improved, and even when the coating amount is small and the curing period is short, high adhesion and moldability can be achieved. able to demonstrate

That is, the adhesive for packaging materials for electricity storage devices of the present invention has the following features: the amount of polyol containing polyester polyol is 20 to 60% by mass based on the polyisocyanate, and the adhesive has a partial structure represented by general formula (1). The effects based on the content of 0.5 to 12.0% by mass work synergistically, and even when the application amount is small and the curing period is short, high cohesive force, substrate followability, and flexibility are achieved. It is possible to achieve excellent adhesive strength, moldability, and heat-and-moisture resistance.

<Polyisocyanate (A)>
The polyisocyanate (A) performs a crosslinking reaction with the hydroxyl group in the polyol (B), increases the molecular weight of the adhesive layer, and plays a role in improving the internal cohesive force that exhibits energy elasticity. In addition, since the isocyanate groups in polyisocyanate (A) can react with water to form urea bonds with high cohesive force, it is possible to increase the cohesive force of the adhesive layer by causing a self-crosslinking reaction during curing. can. In this way, by using polyisocyanate (A), it becomes possible to form a strong adhesive layer, and it becomes possible to improve adhesive strength.

Examples of the polyisocyanate (A) include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, araliphatic polyisocyanates, and various derivatives derived from the above polyisocyanates.

Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, Examples include 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate and 2,6-diisocyanate methyl caproate.

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

Examples of aromatic polyisocyanates include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6 -Tolylene diisocyanate or mixtures thereof, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, triphenylmethane-4,4',4''-triisocyanate, 1,3,5-triisocyanate Examples include isocyanate benzene, 2,4,6-triisocyanate toluene, and 4,4'-diphenyldimethylmethane-2,2'-5,5'-tetraisocyanate.

Examples of the araliphatic polyisocyanate 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.

Examples of derivatives derived from the polyisocyanate include the polyisocyanate, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5- Low-molecular polyols with a molecular weight of less than 200, such as pentanediol, 3,3'-dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol, trimethylolpropane, pentaerythritol, sorbitol, or castor oil, etc. adduct; trimer (also referred to as trimer or nurate) of the diisocyanate; biuret; allophanate; 2,4,6-oxadiazinetrione ring obtained from carbon dioxide gas and the diisocyanate A polyurethane polyisocyanate obtained by reacting a polyisocyanate and a polyol under conditions in which isocyanate groups are in excess.

As the polyol to be reacted with the polyisocyanate, conventionally known polyols can be used. As such polyols, for example, polyester polyols, polyether polyols, polycarbonate polyols, acrylic polyols, and polybutadiene polyols can be used.

(Polyester urethane polyisocyanate)
Polyisocyanate (A) is preferably a polyester which is a reaction product of polyisocyanate and a polyol containing polyester polyol (a2), from the viewpoint of achieving both excellent high temperature durability and high cohesive force and processability. It contains urethane polyisocyanate. Further, as the polyisocyanate for forming the polyester urethane polyisocyanate, aromatic polyisocyanates are preferably used, and among them, adducts (a1) of aromatic polyisocyanates such as tolylene diisocyanate and MDI are preferably used. Particularly preferably used are those containing

(Aromatic polyisocyanate adduct (a1))
Examples of the aromatic polyisocyanate adduct (a1) include an adduct obtained by adding an aromatic diisocyanate monomer to a polyhydric alcohol.
Examples of the diisocyanate monomer include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4- or 2,6- Examples include tolylene diisocyanate or a mixture thereof, 4,4'-toluidine diisocyanate, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and examples of the polyhydric alcohol include ethylene glycol, propylene glycol, butylene glycol, and hexylene. Glycol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolpropane, cyclohexanedimethanol, diethylene glycol, triethylene glycol, dipropylene glycol, glycerol , trimethylolpropane, pentaerythritol, sorbitol, and other low molecular weight polyols with a molecular weight of less than 200, and castor oil.
Examples of the adduct (a1) of such an aromatic polyisocyanate include an adduct of tolylene diisocyanate and trimethylolpropane, an adduct of tolylene diisocyanate and trimethylolpropane and diethylene glycol, and 4,4'-diphenyl diisocyanate. Compounds such as trimethylolpropane and adducts of dipropylene glycol and tripropylene glycol are preferably used.
That is, the polyester urethane polyisocyanate is preferably a polyisocyanate obtained by reacting a polyisocyanate containing an aromatic polyisocyanate adduct (a1) with a polyol containing a polyester polyol (a2). By including the ester structure derived from such a polyester polyol and the urethane structure, it is possible to have both flexibility and cohesive force, and it is possible to exhibit excellent adhesive performance.

The polyisocyanate for forming the above-mentioned polyester urethane polyisocyanate may contain other polyisocyanates other than the aromatic polyisocyanate adduct (a1), and such other polyisocyanates include the above-mentioned polyisocyanates. Examples include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, araliphatic polyisocyanates, and various derivatives derived from the polyisocyanates described in the section (A)>.

(Polyester polyol (a2))
In the present invention, the polyester polyol (a2) is not limited to, but includes, for example, a polyester polyol obtained by reacting a polybasic acid and a polyhydric alcohol; or polycaprolactone, polyvalerolactone, polyester polyol (a2), etc. Examples include polyester polyols obtained by ring-opening polymerization of lactones such as (β-methyl-γ-valerolactone).

Examples of the polybasic acids include dibasic acids having an aromatic ring such as terephthalic acid, isophthalic acid, naphthalene dicarboxylic acid, and phthalic anhydride; adipic acid, azelaic acid, sebacic acid, succinic acid, glutaric acid, and tetrahydrophthalic anhydride. acid, aliphatic dibasic acids such as hexahydrophthalic anhydride, maleic anhydride, itaconic anhydride; or dialkyl esters thereof, or mixtures thereof.

Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, butylene glycol, neopentyl glycol, dineopentyl glycol, trimethylolpropane, glycerin, 1,6-hexanediol, 1,4-butanediol, 1,4-cyclohexanedimethanol, 3-methyl-1,5-pentanediol, 3,3'-dimethylolheptane, 1,9-nonanediol, polyoxyethylene glycol, polyoxypropylene Examples include diols such as glycol, polytetramethylene ether glycol, polyether polyol, polycarbonate polyol, polyolefin polyol, acrylic polyol, and polyurethane polyol; or mixtures thereof.
The above-mentioned polybasic acids and polyhydric alcohols may each be used singly, but it is preferable to use two or more types together.

The polyhydric alcohol that is a component of the polyester polyol (a2) preferably contains 5 to 30 mol% of a polyhydric alcohol having a partial structure represented by the following general formula (1) based on 100 mol% of the polyhydric alcohol. . When the content is 5 mol% or more, the affinity with water increases, and the effect of shortening the curing time is likely to occur. When it is 30 mol% or less, the polyisocyanate (A) does not become too flexible and has excellent adhesiveness at high temperatures.

General formula (1)
[In general formula (1), R represents a hydrogen atom or a methyl group, and n represents an integer of 2 to 20. ]

Examples of the polyhydric alcohol having the above partial structure include diethylene glycol, triethylene glycol, dipropylene glycol, and tripropylene glycol. In addition, the polyhydric alcohol having the above partial structure can be prepared using an oxirane compound such as ethylene oxide, propylene oxide, butylene oxide, or tetrahydrofuran using water, a low molecular weight polyol such as ethylene glycol, propylene glycol, trimethylolpropane, or glycerin as an initiator. It may also be polyoxyalkylene glycol obtained by polymerization. From the viewpoint of reactivity and appropriate hydrophilicity, those having an oxyethylene structure are preferred. Furthermore, from the viewpoint of compatibility between the polyhydric alcohol and other raw materials, diethylene glycol is preferred.

The weight average molecular weight (Mw) of the polyester polyol (a2) is preferably 5,000 to 30,000. When the weight average molecular weight is 5,000 or more, the adhesiveness to the base material is further improved and the processability is excellent. When the weight average molecular weight is 30,000 or less, the concentration of hydroxyl groups at the terminals of the polyester polyol (a2) can be easily prevented from becoming excessively low, and the polyester polyol (a2) can be easily prevented from being reacted with the trifunctional or higher aromatic polyisocyanate (a1). When obtaining polyisocyanate (A), prolongation of the reaction time can be easily prevented.

The hydroxyl value (OHV) of the polyester polyol (a2) is preferably 2 to 35 mgKOH/g, more preferably 10 to 20 mgKOH/g. The hydroxyl group is used in the reaction with the trifunctional or higher functional aromatic polyisocyanate (a1), and as the reaction progresses, the adhesive has a high molecular weight, and the heat resistance as a packaging material can be improved. The above hydroxyl value can be determined by a method based on JIS K 1557-1.

The glass transition temperature (Tg) of the polyester polyol (a2) is preferably in the range of -20 to 5°C, more preferably in the range of -10 to 0°C. By setting it within the above range, it becomes easy to control the cohesive force of the adhesive, and it is possible to obtain an appropriate cohesive force according to the adhered substrate, required performance, etc.

The reaction temperature for converting the trifunctional or higher functional aromatic polyisocyanate (a1) and the polyester polyol (a2) into urethane is preferably 50 to 180°C, preferably 60 to 100°C. A temperature of 50 to 180°C is preferable because the urethanization reaction proceeds efficiently.

The NCO% contained in the polyisocyanate (A) is preferably 1.0 to 8.0% by mass, more preferably 4.0 to 6.0% by mass in terms of solid content. When it is 1.0% by mass or more, the amount of urethane bonding after curing becomes sufficient, increasing cohesive force and improving adhesive strength. When the content is 8.0% by mass or less, the time required for curing can be shortened, and poor appearance due to foaming or the like can be suppressed.

<Polyol (B)>
The polyol (B) used in the present invention is characterized by containing a polyester polyol (b1). By including the polyester polyol (b1), the adhesiveness with the base material is improved, and excellent adhesive strength and moldability can be exhibited. Moreover, polyester polyol (b1) is suitable also from the viewpoint of easy introduction of the partial structure of general formula (1).

(Polyester polyol (b1))
As the polyester polyol (b1), for example, a polyester polyol obtained by reacting a polybasic acid and a polyhydric alcohol; or a lactone such as polycaprolactone, polyvalerolactone, poly(β-methyl-γ-valerolactone), etc. Examples include polyester polyols obtained by ring-opening polymerization of As such a polyester polyol (b1), those described in the section of (polyester polyol (a2)) in <Polyisocyanate (A)> mentioned above can be used.
Further, the polyhydric alcohol that is a component of the polyester polyol (b1) is a polyhydric alcohol that has a partial structure represented by the general formula (1) in the polyhydric alcohol that is a component, similarly to the polyester polyol (a2). It may also contain alcohol. The content of the polyhydric alcohol having a partial structure is preferably 5 to 30 mol% in 100 mol% of the polyhydric alcohol.

The weight average molecular weight of the polyester polyol (b1) is preferably 5,000 to 60,000. When the weight average molecular weight is 5,000 or more, the adhesiveness to the base material is further improved and the processability is excellent. When the weight average molecular weight is 60,000 or less, the compatibility when mixed with polyisocyanate (A) is excellent, and the appearance is good.

Further, the hydroxyl value of the polyester polyol (b1) is preferably 5 to 20 mgKOH/g, and the glass transition temperature of the polyester polyol (b1) is preferably -20 to 50°C, more preferably -5 to 35°C. range.

(Hydroxy group-containing epoxy resin (b2))
It is preferable that the polyol (B) further contains a hydroxyl group-containing epoxy resin (b2) from the viewpoint of adhesive strength and heat-and-moisture resistance. By using the hydroxyl group-containing epoxy resin (b2) in combination, the high temperature adhesive strength to metal materials such as metal foil, the heat resistance and heat resistance durability of the molded product are improved. The content of the hydroxyl group-containing epoxy resin (b2) is preferably 5 to 50% by mass based on the mass of the polyol (B). When the content is 5% by mass or more, adhesive strength and heat-and-moisture resistance are excellent. When it is 50% by mass or less, moldability is excellent. From the viewpoint of the balance between adhesive strength, moldability, and heat and humidity resistance, the content is more preferably 10 to 30% by mass.

Examples of the hydroxyl group-containing epoxy resin (b2) include bisphenol A epoxy resin, bisphenol F epoxy resin, polyglycerol polyglycidyl ether, sorbitol polyglycidyl ether, and trimethylolpropane polyglycidyl ether. From the viewpoint of adhesiveness and durability of the molded product, bisphenol A type epoxy resin is preferred. These hydroxyl group-containing epoxy resins may be used alone or in combination of two or more.

(Other polyols)
Polyol (B) may further contain known polyols other than (b1) and (b2) within a range that does not impair the effects of the present invention. Examples of such polyols include polyether polyols, polyurethane polyols, polycarbonate polyols, and acrylic polyols, and polyols may also be reacted with polyisocyanates to introduce urethane bonds.

<Solvent>
The adhesive of the present invention may contain a solvent in the drying process within a range that does not affect the base material in order to adjust the coating liquid to an appropriate viscosity when applying the adhesive to a base material. . Examples of solvents include ketone compounds such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester compounds such as methyl acetate, ethyl acetate, butyl acetate, ethyl lactate, and methoxyethyl acetate; ether compounds such as diethyl ether and ethylene glycol dimethyl ether. Compounds; aromatic compounds such as toluene and xylene; aliphatic compounds such as pentane and hexane; and halogenated hydrocarbon compounds such as methylene chloride, chlorobenzene and chloroform.

<Manufacture of adhesive for packaging materials for electricity storage devices>
The adhesive of the present invention contains at least the polyisocyanate (A) and a polyol (B) containing the polyester polyol (b1), and the content of the polyol (B) is greater than the mass of the polyisocyanate (A). and the content of the partial structure represented by the above general formula (1) is 0.5 to 12.0% by mass based on the solid mass of the adhesive. good.

In the adhesive of the present invention, when blending polyisocyanate (A) and polyol (B), the ratio of the number of isocyanate groups in polyisocyanate (A) to the number of hydroxyl groups in polyol (B) (Number of NCO moles/OH mole) The number) is preferably 5 to 20, more preferably 8 to 12. When it is 5 or more, the amount of urethane bonds after curing is sufficient, the cohesive force is increased, and the heat resistance and heat resistance durability of the molded product are improved. When it is 20 or less, the time required for curing can be shortened and poor appearance due to foaming etc. can be suppressed.

The adhesive of the present invention may further contain other components as long as the effects of the present invention are not impaired. Such optional components may be blended with one or both of the polyisocyanate (A) and the polyol (B), or may be added when blending the polyisocyanate (A) and the polyol (B), Each type may be used alone or two or more types may be used in combination.

(Antioxidant)
The adhesive of the present invention may contain an antioxidant in order to suppress thermal oxidative deterioration. Examples of antioxidants include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, and stearin-β-(3, Monophenolic antioxidants such as 5-di-t-butyl-4-hydroxyphenyl) propionate; 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4- ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), and 3,9- Bis[1,1-dimethyl-2-[β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl]2,4,8,10-tetraoxaspiro[5,5] Bisphenol antioxidants such as undecane; 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris( 3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3 , 3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid] glycol ester, and 1,3,5-tris(3',5'-di-t-butyl-4' Examples include polymeric phenolic antioxidants such as -hydroxybenzyl)-S-triazine-2,4,6-(1H, 3H, 5H)trione and triphenol. Among these, high molecular weight hindered phenol antioxidants such as tetraphenol and triphenol are preferably used.

(reaction accelerator)
The adhesive of the present invention may further contain a reaction accelerator in order to promote the urethanization reaction. Examples of reaction accelerators include metal catalysts such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltin dilaurate, and dibutyltin dimalate; 1,8-diaza-bicyclo(5,4,0)undecene-7,1, Tertiary amines such as 5-diazabicyclo(4,3,0)nonene-5,6-dibutylamino-1,8-diazabicyclo(5,4,0)undecene-7; reactive tertiary amines such as triethanolamine An example is an amine.

(Silane coupling agent)
The adhesive of the present invention may further contain a silane coupling agent in order to improve adhesive strength to metal materials such as metal foil. Examples of the silane coupling agent include trialkoxysilanes having a vinyl group such as vinyltrimethoxysilane and vinyltriethoxysilane; 3-aminopropyltriethoxysilane, N-(2-aminoethyl)3-aminopropyltrimethoxysilane; Trialkoxysilane having an amino group such as silane; Trialkoxysilane having
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, based on 100 parts by mass of the solid content of the adhesive for power storage device packaging material. By adding a silane coupling agent within the above range, the adhesive strength to metal foil can be further improved.

(Phosphorous oxygen acid or its derivative)
The adhesive of the present invention can contain a phosphorus oxygen acid or a derivative thereof in order to improve adhesive strength to metal materials such as metal foil. The phosphorus oxygen acid may be one having at least one free oxygen acid, such as phosphoric acids such as hypophosphorous acid, phosphorous acid, orthophosphoric acid, and hypophosphoric acid; metaphosphoric acid, Examples include condensed phosphoric acids such as pyrophosphoric acid, tripolyphosphoric acid, polyphosphoric acid, and ultraphosphoric acid. Examples of derivatives of phosphorus oxyacids include those that are partially esterified with alcohols while leaving at least one free oxyacid in the phosphorus oxyacid. Examples of the alcohol include aliphatic alcohols such as methanol, ethanol, ethylene glycol, and glycerin; aromatic alcohols such as phenol, xylenol, hydroquinone, catechol, and phloroglycinol.
The content of the phosphorus oxygen acid or its derivative is preferably 0.01 to 10 parts by mass, more preferably 0.05 to 5 parts by mass, based on 100 parts by mass of the solid content of the adhesive for electricity storage device packaging material. More preferably, it is 0.05 to 1 part by mass.

(Leveling agent or antifoaming agent)
The adhesive of the present invention may further contain a leveling agent or an antifoaming agent to improve the laminate appearance of the packaging material. Examples of leveling agents include polyether-modified polydimethylsiloxane, polyester-modified polydimethylsiloxane, aralkyl-modified polymethylalkylsiloxane, polyester-modified hydroxyl-containing polydimethylsiloxane, polyetherester-modified hydroxyl-containing polydimethylsiloxane, and acrylic copolymers. , methacrylic copolymers, polyether-modified polymethylalkylsiloxanes, acrylic acid alkyl ester copolymers, methacrylic acid alkyl ester copolymers, and lecithin.
Examples of antifoaming agents include silicone resins, silicone solutions, and copolymers of alkyl vinyl ethers, acrylic acid alkyl esters, and methacrylic acid alkyl esters.

(Additive)
The adhesive of the present invention may contain various additives as long as the effects of the present invention are not impaired. Examples of additives include inorganic fillers such as silica, alumina, mica, talc, aluminum flakes, and glass flakes, layered inorganic compounds, and stabilizers (antioxidants, heat stabilizers, ultraviolet absorbers, hydrolysis inhibitors, etc.) ), rust inhibitors, thickeners, plasticizers, antistatic agents, lubricants, antiblocking agents, colorants, fillers, crystal nucleating agents, and catalysts for adjusting the curing reaction.

<Packaging material for power storage devices>
The adhesive of the present invention can be used as an adhesive forming an adhesive layer of a packaging material for an electricity storage device.
Among these, it can be suitably used as an outer layer adhesive forming an outer layer adhesive layer of a packaging material for an electricity storage device. The electricity storage device packaging material of the present invention has a structure in which at least an outer resin film layer, an outer adhesive layer, a metal foil layer, and a heat seal layer are laminated in this order from the outside, and the outer layer side The adhesive layer is characterized in that it is a cured product of the above-described adhesive for packaging materials for electricity storage devices.
The method for manufacturing the packaging material for an electricity storage device is not particularly limited, and can be manufactured by a known method.
For example, an outer resin film layer and a metal foil layer are laminated using the above-mentioned adhesive for power storage device packaging materials that forms the outer adhesive layer, so that outer resin film layer/outer adhesive layer/ After obtaining the intermediate laminate having the structure of the metal foil layer, it can be manufactured by laminating a heat seal layer on the metal foil layer surface of the intermediate laminate using an inner layer side adhesive (hereinafter, manufacturing method 1).
Alternatively, after laminating a metal foil layer and a heat-sealing layer using an inner-layer adhesive to obtain an intermediate laminate having a structure of metal foil layer/inner-layer adhesive layer/heat-sealing layer, the power storage device is packaged. It can be manufactured by laminating the metal foil layer and the outer resin film layer of the intermediate laminate using a material adhesive (hereinafter, manufacturing method 2).

In the case of manufacturing method 1, the adhesive for power storage device packaging material is applied to one side of the base material of either the outer resin film layer or the metal foil layer, and after volatilizing the solvent, the adhesive for the uncured outer layer is applied. It is preferable to overlay the other base material on the adhesive layer under heat and pressure, and then age the adhesive layer at room temperature to less than 100°C to cure the outer adhesive layer. When the aging temperature is less than 100° C., thermal shrinkage of the outer resin film layer does not occur, so there is no reduction in elongation at break or stress at break, which affects molding, and there is no reduction in molding productivity due to film curl.
The coating amount of the outer layer adhesive after drying is preferably about 1 to 15 g/m ² .
Similarly, in the case of manufacturing method 2, the adhesive for the electricity storage device packaging material may be applied to either the outer resin film layer or the metal foil layer surface of the intermediate laminate.

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

[Outer resin film layer]
The outer resin film layer is not particularly limited, but it is preferable to use at least one stretched film selected from the group consisting of polyamide, polyester, and polyimide, and more preferably polyester from the viewpoint of stretchability and heat resistance during molding. It's a film. Examples of the polyester include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, and polycyclohexane dimethylene terephthalate.
The outer resin film layer may be colored with a pigment such as carbon black or titanium oxide. In addition, the non-laminated surface of the outer resin film layer may be coated with a coating agent for the purpose of preventing scratches and electrolyte resistance, or a slip agent for the purpose of imparting slipperiness during molding, and improving the design. It may also be purposely coated with printing ink. Moreover, the outer resin film layer may be a laminated film in which two or more layers of films are laminated in advance. The thickness of the outer resin film layer is not particularly limited, but is preferably 12 to 100 μm.

[Metal foil layer]
The metal foil layer is not particularly limited, but may be a stainless steel foil layer or an aluminum foil layer. The thickness of the metal foil layer is not particularly limited, but is preferably 20 to 80 μm. In addition, the surface of the metal foil layer can be treated with chromate phosphate, chromate chromate, trivalent chromium, zinc phosphate, zirconium phosphate, zirconium oxide, titanium phosphate, hydrofluoric acid, or cerium. It is preferable that a known preservative treatment such as hydrotalcite treatment is applied. The antiseptic treatment can suppress corrosion and deterioration of the metal foil surface caused by the electrolyte of the battery. Further, a known organic component such as a phenol resin, an amide resin, an acrylic resin, a polyvinyl alcohol, a coupling agent, etc. is applied to the preservative-treated surface, or a mixture of the preservative-treated component and the organic component is applied. It is preferable that the metal foil layer is subjected to baking treatment at a high temperature of about 200°C. By performing such an organic primer treatment, the metal foil and the adhesive can be bonded more firmly, and lifting between the metal foil and the adhesive can be further suppressed.

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

[Inner adhesive layer]
The adhesive forming the inner adhesive layer is not particularly limited, but it is preferable that the adhesive strength between the metal foil layer and the heat seal layer is not reduced by the electrolyte of the electricity storage device, and the adhesive for the packaging material of electricity storage devices of the present invention Besides, known adhesives can be used.
For the inner adhesive layer, for example, an adhesive combining a polyolefin resin and a polyisocyanate or an adhesive combining a polyol and a polyisocyanate is applied to the metal foil layer using a gravure coater or the like, and the solvent is dried. It can be formed by overlapping the heat-sealing layer on the adhesive layer under heating and pressure, and then aging at room temperature or under heating.
Alternatively, an adhesive such as acid-modified polypropylene is melt-extruded onto the metal foil layer using a T-die extruder to form an adhesive layer, and a heat seal layer is stacked on the adhesive layer, and the metal foil layer and the heat seal layer are formed. By bonding these together, an inner adhesive layer can be formed.
If both the outer adhesive layer and the inner adhesive layer require aging, the outer resin film layer, the uncured outer adhesive layer, the metal foil layer, and the uncured inner adhesive layer After obtaining a laminate having a structure in which the heat seal layer and the heat seal layer are laminated in this order from the outside, aging may be performed all at once.

<Container for electricity storage device>
The container for a power storage device of the present invention can be obtained by molding the packaging material for a power storage device of the present invention so that the outer resin film layer forms a convex surface and the heat seal layer forms a concave surface. Note that the "concave surface" as used in the present invention refers to a surface that has a depression that can accommodate an electrolytic solution when a flat packaging material for an electricity storage device is molded into a tray shape as shown in FIG. This means that the "convex surface" in the present invention refers to the back surface of the surface having the depressions.

<Electricity storage device>
The electricity storage device of the present invention uses the above-mentioned container for electricity storage device, and is suitable for use in, for example, secondary batteries such as lithium ion batteries, nickel metal hydride batteries, and lead acid batteries, and electrochemical capacitors such as electric double layer capacitors. can be mentioned. A typical power storage device includes a battery element including an electrode, a lead extending from the electrode, and a container for storing the battery element, and in the power storage device of the present invention, the container for the power storage device is used as the container for storing the power storage device. The storage container is formed from a packaging material for an electricity storage device so that the heat-sealing layer is on the inside, and the heat-sealing layers of the two packaging materials are stacked facing each other, and the peripheral edges of the stacked packaging materials are overlapped. It may be obtained by heat-sealing, or one packaging material may be folded back and overlapped, and the peripheral edge of the packaging material may be similarly heat-sealed.

Hereinafter, the present invention will be explained 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)>
Approximately 1 g of a sample (polyester polyol solution) was accurately weighed into a stoppered Erlenmeyer flask, and 100 ml of a toluene/ethanol (volume ratio: toluene/ethanol = 2/1) mixed solution was added to dissolve it. To this, a phenolphthalein test solution was added as an indicator and held for 30 seconds. Thereafter, the solution was titrated with a 0.1N alcoholic potassium hydroxide solution until it turned pale pink, and the acid value (mgKOH/g) was determined using the following formula.
Acid value (mgKOH/g) = (5.611 x a x F)/S
However, S: Sample amount (g)
a: Consumption amount (ml) of 0.1N alcoholic potassium hydroxide solution
F: Titer of 0.1N alcoholic potassium hydroxide solution

<Measurement of hydroxyl value (OHV)>
Approximately 1 g of a sample (polyester polyol, hydroxyl group-containing urethane resin, etc.) was accurately weighed into a stoppered Erlenmeyer flask, and 100 ml of a toluene/ethanol (volume ratio: toluene/ethanol = 2/1) mixed solution was added and dissolved. Furthermore, exactly 5 ml of an acetylating agent (a solution of 25 g of acetic anhydride dissolved in pyridine to a volume of 100 ml) was added, and the mixture was stirred for about 1 hour. To this, phenolphthalein test solution was added as an indicator and the test was continued for 30 seconds. Thereafter, the solution was titrated with a 0.5N alcoholic potassium hydroxide solution until it turned pale pink, and the hydroxyl value (mgKOH/g) was determined using the following formula.
Hydroxyl value (mgKOH/g) = [{(ba) x F x 28.05}/S] + D
However, S: Sample amount (g)
a: Consumption amount (ml) of 0.5N alcoholic potassium hydroxide solution
b: Consumption amount (ml) of 0.5N alcoholic potassium hydroxide solution in blank experiment
F: Titer of 0.5N alcoholic potassium hydroxide solution
D: Acid value (mgKOH/g)

<Method for measuring NCO content (mass%)>
Approximately 1 g of the sample was weighed into a 200 mL Erlenmeyer flask, and 10 mL of a toluene solution of 0.5N di-n-butylamine and 10 mL of toluene were added to dissolve the sample. Next, a phenolphthalein test solution was added as an indicator, held for 30 seconds, and then titrated with a 0.25N hydrochloric acid solution until the solution turned pale pink. The NCO content (mass%) was determined by the following (Equation 3).
(Formula 3): NCO (mass%) = {(ba) x 4.202 x F x 0.25}/S
However, S: Amount of sample collected (g)
a: Consumption amount of 0.25N hydrochloric acid solution (ml)
b: Consumption amount (ml) of 0.25N hydrochloric acid solution in blank experiment
F: Titer of 0.25N hydrochloric acid solution

<Measurement of weight average molecular weight (Mw), number average molecular weight (Mn), and molecular weight distribution (Mw/Mn)>
The weight-average molecular weight and number-average molecular weight are calculated using Showdex (registered trademark) (manufactured by Showa Denko K.K.), columns: KF-805L, KF-803L, and KF-802 (all product names, manufactured by Showa Denko K.K.). ), the column temperature was 40° C., the eluent was THF, the flow rate was 0.2 ml/min, the detection was RI, and the sample concentration was 0.02% by mass. Values were measured in terms of standard polystyrene. Molecular weight distribution was calculated from the obtained values.

<Glass transition temperature (Tg)>
The glass transition temperature was measured by DSC (differential scanning calorimeter). Specifically, approximately 2 mg of the compound to be measured is weighed on an aluminum pan, the aluminum pan is set in a DSC measurement holder, and the endothermic peak on the chart obtained under the temperature increase condition of 5°C/min is read. The peak temperature at 100°C was taken as the glass transition temperature.

<<Production of polyisocyanate (A)>>
<Synthesis of aromatic polyisocyanate adduct (a1)>
(Aromatic polyisocyanate adduct (a1-1))
After 239 parts of tolylene diisocyanate was charged and 61 parts of molten trimethylolpropane was added dropwise while stirring at room temperature, the reaction was carried out at 60°C for 2 hours. Then, it was diluted with ethyl acetate to adjust the nonvolatile content to 50%, and then taken out. The obtained aromatic polyisocyanate adduct (a1-1) had a solid NCO% of 19.0%, and the amount of the partial structure of general formula (1) was 0%.

(Aromatic polyisocyanate adduct (a1-2))
After 238 parts of tolylene diisocyanate was charged and a mixed solution of 46 parts of molten trimethylolpropane and 15 parts of diethylene glycol was added dropwise while stirring at room temperature, the reaction was carried out at 60°C for 2 hours. Next, it was diluted with ethyl acetate to adjust the nonvolatile content to 50%, and then taken out. The obtained aromatic polyisocyanate adduct (a1-2) had a solid NCO% of 19.4%, and the amount of the partial structure of general formula (1) was 4.4%.

(Aromatic polyisocyanate adduct (a1-3))
244 parts of 4,4'-diphenylmethane diisocyanate was charged, and while stirring at 40°C, a mixed solution of 32 parts of molten trimethylolpropane and 15 parts of dipropylene glycol was added dropwise, followed by a reaction at 60°C for 2 hours. . Then, it was diluted with ethyl acetate to adjust the nonvolatile content to 50%, and then taken out. The resulting aromatic polyisocyanate adduct (a1-3) had a solid NCO% of 14.0%, and the amount of the partial structure of general formula (1) was 5.9%.

<Synthesis of polyester polyol (a2)>
(Polyester polyol (a2-1))
166 parts of isophthalic acid, 166 parts of terephthalic acid, 293 parts of adipic acid, 87 parts of ethylene glycol, 146 parts of neopentyl glycol, and 142 parts of 1,6-hexanediol were charged, and an esterification reaction was carried out at 170 to 230°C for 8 hours. . After distilling off a predetermined amount of water, 0.13 parts of tetraisobutyl titanate was added, the pressure was gradually reduced, and transesterification was carried out at 1.3 to 2.6 hPa and 230 to 250°C for 3 hours, resulting in a number average molecular weight of 9. 620, a weight average molecular weight of 190,700, a molecular weight distribution of 2.05, a hydroxyl value of 10.1 mgKOH/g, and a glass transition temperature of -1.2°C. A polyester polyol (a2-1) was obtained.
Assuming that the total of polybasic acid and polyhydric alcohol is 200 mol%, the composition of the obtained polyester polyol (a2-1) is as shown in Table 1-2: isophthalic acid: terephthalic acid: adipic acid: ethylene Glycol: neopentyl glycol: 1,6-hexanediol = 30:30:40:35:35:30 (mol%).

(Polyester polyol (a2-2) to (a2-14))
Polyester polyol (a2-1 ), a polybasic acid and a polyhydric alcohol were reacted to obtain polyester polyols (a2-2) to (a2-14).

The composition ratio (mass %) and composition ratio (mol %) of the obtained polyester polyol (a2) are shown in Table 1-1 and Table 1-2 (hereinafter abbreviated as Table 1).

The abbreviations in Table 1 and Table 3 described below are as follows.
PA: Phthalic anhydride IPA: Isophthalic acid TPA: Terephthalic acid AdA: Adipic acid SeA: Sebacic acid AzA: Azelaic acid EG: Ethylene glycol NPG: Neopentyl glycol 1,6-HD: 1,6-hexanediol MPO: 2- Methyl-1,3-propanediol DEG: diethylene glycol TEG: triethylene glycol PEG: polyethylene glycol (hydroxyl value 281 mgKOH/g, molecular weight 400)
PPG: Polypropylene glycol (hydroxyl value 280mgKOH/g, molecular weight 400)

<Synthesis of polyisocyanate (A)>
(Polyisocyanate (A-1))
100 parts of polyester polyol (a2-1), 2.5 parts of 1,4-butanediol, and 102.5 parts of ethyl acetate were placed in a 4-necked flask, heated to 100°C, and stirred until the solution became uniform. To this, 65 parts of aromatic polyisocyanate adduct (a1-1) was added in solid terms, and the reaction was carried out at 80° C. for 4 hours. After the reaction was completed, the non-volatile content was adjusted to 50% with ethyl acetate and taken out. The obtained polyisocyanate (A-1) had a solid NCO% of 5.6% and a content of the partial structure represented by the general formula (1) of 0.0% by mass.

(Polyisocyanate (A-2) to (A-22))
Polyisocyanate (A-2) prepared by reacting polyol and polyisocyanate in the same manner as polyisocyanate (A-1) except for changing the blending amounts shown in Table 2, and adjusting the nonvolatile content to 50% with ethyl acetate. ~(A-22) was obtained.

The abbreviations in Table 2 are as follows.
1,4-BD: 1,4-butanediol NPG: Neopentyl glycol

<<Production of polyol (B)>>
<Synthesis of polyester polyol (b1)>
(Polyester polyol (b1-1) to (b1-8))
Polyester polyol (a2-1 ), a polybasic acid and a polyhydric alcohol were reacted to obtain polyester polyols (b1-1) to (b1-8).

The composition ratio (mass %) and composition ratio (mol %) of the obtained polyester polyol (b1) are shown in Table 3-1 and Table 3-2.

<Adjustment of polyol (B)>
(Polyol (B-1) to (B-16))
Polyester polyol (b1), hydroxyl group-containing epoxy resin (b2), and ethyl acetate as a solvent were mixed and dissolved in the amounts shown in Table 4, and the nonvolatile content was adjusted to 50%. B-16) was obtained.

The abbreviations in Table 4 are as follows.
NPEL-134: Bisphenol A type epoxy resin (manufactured by NAN YA PLASTICS, epoxy equivalent 230-270)
jER152: Phenol novolac type polyfunctional epoxy resin (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent: 178)

<Manufacture of adhesive for packaging materials for electricity storage devices>
[Example 1]
100 parts of a 50% nonvolatile solution of polyisocyanate (A-1), 36 parts of a 50% nonvolatile solution of polyol (B-3), and 1 part of glycidopropyltrimethoxysilane (Si coupling agent) as an additive. 0 parts of dibutyltin dilaurate (DBTDL) as a catalyst, and ethyl acetate were adjusted to a solid content concentration of 30%, and stirred for 10 minutes to obtain an adhesive.

[Examples 2 to 38, Comparative Examples 1 to 7]
The same procedure as in Example 1 was carried out, except that the types and amounts of polyisocyanate (A), polyol (B), Si coupling, and catalyst were changed to those shown in Tables 5 and 6. Got the glue.

<Evaluation of adhesives for packaging materials for electricity storage devices>
Packaging materials were manufactured using the obtained adhesive, and the following evaluations were performed. The results are shown in Tables 5 and 6.

[Manufacture of packaging materials]
Using a dry laminator, the obtained adhesive was applied as an outer adhesive layer onto one side of a 40 μm thick aluminum foil. After volatilizing the solvent, a stretched polyamide film having a thickness of 30 μm was laminated to obtain an intermediate laminate. The amount of adhesive applied after drying was 3 g/m ² . Next, using a dry laminator, an adhesive for an inner adhesive layer, which will be described later, was applied to the other surface of the aluminum foil of the obtained intermediate laminate. After volatilizing the solvent, unstretched polypropylene films having a thickness of 30 μm were laminated to obtain a laminate. The amount of adhesive applied after drying was 4 g/m ² .
Next, aging was performed for 2 days and 4 days at 40° C. and 60% RH (relative humidity) to harden the outer and inner adhesive layers to form an outer resin film layer/outer adhesive layer/ A packaging material having a structure of metal foil layer/inner adhesive layer/heat seal layer was obtained.

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

[Lamination strength]
The packaging materials aged for 2 days at 40°C and 60% RH were cut into pieces of 200 mm x 15 mm and subjected to a T-peel test using a tensile tester to determine the peel strength between the stretched polyamide film and aluminum foil. (N/15mm width) was measured. The measurement was performed at a loading rate of 300 mm/min in an environment of 20° C. and 65% RH, and was evaluated based on the average value of 5 test pieces based on the following criteria.
S: Average value of peel strength is 7N or more (very good)
A: Average value of peel strength is 4N or more and less than 7N (good)
B: Average value of peel strength is 2N or more and less than 4N (usable)
C: Average value of peel strength is less than 2N (unusable)

[Moldability]
The packaging material aged for 2 days at 40°C and 60% RH and the packaging material aged for 4 days in the same environment were each cut into a size of 80 x 80 mm, and molded with the stretched polyamide film on the outside. One-step overhang molding was performed using a straight mold with free height. The maximum molding height without breaking the aluminum foil or lifting between the layers was determined, and the moldability was evaluated using 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 depending on the molding height.
S: Maximum molding height is 6 mm or more (very good)
A: Maximum molding height is 4 mm or more and less than 6 mm (good)
B: Maximum molding height is 2 mm or more and less than 4 mm (usable)
C: Maximum molding height is less than 2mm (unusable)

[Moisture heat resistance]
The packaging materials aged for 2 days at 40°C and 60% RH were cut into pieces of 80 x 80 mm, with the stretched polyamide film facing outside, and molded to a molding height of 3 mm using a straight mold with free molding height. A molded product was obtained by performing one-step overhang molding.
Next, the molded product was placed in a constant temperature and humidity chamber at 85°C and 85% RH and allowed to stand for 168 hours, and then taken out from the constant temperature and humidity chamber and visually checked to see if any floating occurred. 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.
S: No floating (very good)
A: Lifting occurs on one of the four sides (good)
B: Lifting occurs on two of the four sides (usable)
C: Lifting occurs on 3 or more of the 4 sides (unusable)

According to Tables 5 and 6, polyol (B) contains polyester polyol (b1), is 20 to 60% by mass based on polyisocyanate (A), and is further represented by general formula (1). The adhesive of the present invention containing 0.5 to 12.0% by mass of partial structures has a low adhesive coating amount of 3 g/m ² and exhibits high adhesion even when the curing time is shortened to 2 days. It was able to exhibit both excellent moldability and long-term durability under high temperature and high humidity conditions.
In particular, those containing the hydroxyl group-containing epoxy resin (b2) in an amount of 5 to 50% by mass based on the polyol (B) had excellent lamination strength and heat-and-moisture resistance.
Furthermore, those using bisphenol A type epoxy resin as the hydroxyl group-containing epoxy resin (b2) had excellent lamination strength and moldability.

On the other hand, since Comparative Example 1 does not have the partial structure represented by general formula (1), the curing reaction progresses insufficiently, and when the amount of adhesive applied is reduced and the curing period is shortened to 2 days, , lamination strength and moldability cannot be satisfied.
Comparative Examples 5 and 6 correspond to the examples of JP-A-2018-110086, and like Comparative Example 1, they do not have the partial structure represented by the general formula (1). Therefore, when the amount of adhesive applied is reduced and the curing period is further shortened to two days, the curing reaction progresses insufficiently and satisfactory adhesive performance cannot be achieved.
Comparative Example 2, in which the amount of the partial structure represented by the general formula (1) exceeds 12.0% by mass, has too high an affinity for water, so it easily entrains moisture in the air, making it difficult to obtain satisfactory heat-and-moisture resistance. I can't.
In addition, in Comparative Example 3 in which the amount of polyol (B) is less than 20%, the adhesive layer becomes too rigid, so that it is not possible to achieve both adhesive strength and moldability. In Comparative Example 4 in which the amount of polyol (B) exceeds 60%, the urethane concentration in the adhesive layer decreases, and the cohesive force of the adhesive decreases. Moreover, since the affinity with the base material is also reduced, adhesive strength and moist heat resistance cannot be satisfied.
Comparative Example 7 contains the hydroxyl group-containing epoxy resin (b2) but does not contain the polyester polyol (b1), which reduces the flexibility of the adhesive layer. Therefore, the amount of adhesive applied was reduced and the curing period was increased. If the time is shortened to 2 days, it is not possible to achieve both moldability and moist heat resistance of the molded product.

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

Claims (9)

An adhesive for power storage device packaging material containing polyisocyanate (A) and polyol (B),
The polyol (B) contains a polyester polyol (b1),
The polyol (B) contains 20 to 60% by mass based on the mass of the polyisocyanate (A),
An adhesive for packaging materials for electricity storage devices, which contains a partial structure represented by the following general formula (1) in an amount of 0.5 to 12.0% by mass based on the solid mass of the adhesive.
General formula (1)
[In general formula (1), R represents a hydrogen atom or a methyl group, and n represents an integer of 2 to 20. ] The adhesive for an electricity storage device packaging material according to claim 1, wherein the polyisocyanate (A) contains a reaction product of a polyisocyanate and a polyol including a polyester polyol (a2). The electricity storage device packaging according to claim 1, wherein the polyisocyanate (A) contains a reaction product of a polyisocyanate containing an aromatic polyisocyanate adduct (a1) and a polyol containing a polyester polyol (a2). Adhesive for materials. Claim 2, wherein the polyhydric alcohol that is a component of the polyester polyol (a2) contains 5 to 30 mol% of a polyhydric alcohol having a partial structure represented by general formula (1) in 100 mol% of the polyhydric alcohol. Or the adhesive for electricity storage device packaging materials according to 3. The power storage according to any one of claims 1 to 3, wherein the polyol (B) further contains a hydroxyl group-containing epoxy resin (b2) in a range of 5 to 50% by mass based on the mass of the polyol (B). Adhesive for device packaging materials. The adhesive for an electricity storage device packaging material according to claim 5, wherein the hydroxyl group-containing epoxy resin (b2) is a bisphenol A epoxy resin. An electricity storage device packaging material having a structure in which at least an outer resin film layer, an outer adhesive layer, a metal foil layer, an inner adhesive layer, and a heat seal layer are laminated in this order,
An electricity storage device packaging material, wherein the outer adhesive layer is a cured product of the adhesive for electricity storage device packaging material according to any one of claims 1 to 3. A container for a power storage device formed from the power storage device packaging material according to claim 7, wherein the outer resin film layer forms a convex surface and the heat seal layer forms a concave surface. An electricity storage device comprising the electricity storage device container according to claim 8.