Adhesive composition and thermally adhesive member using same

Abstract

An adhesive composition according to the present invention contains an acid-modified polyolefin, a polyfunctional isocyanate compound, and a curing catalyst, and is characterized in that: the ratio of the total number of isocyanate groups [NCO] (unit: mol) of the polyfunctional isocyanate compound to the total number of carboxy groups [COOH] (unit: mol) of the acid-modified polyolefin ([NCO] / [COOH]) is 7-40, said total number of carboxy groups including acid anhydride structures (-CO-O-CO-) contained in the acid-modified polyolefin as two moles of carboxy groups per one mole of the acid-modified polyolefin; the curing catalyst contains Sn; and the Sn content is 500-4,000 ppm in relation to the total weight of the acid-modified polyolefin and the polyfunctional isocyanate compound.

Description

Adhesive composition and heat-sealable member using the same

[0001] The present invention relates to an adhesive composition, and a heat-sealable member and a packaging material for an electricity storage device using the same, which can be used in various industrial product fields such as the electrical field, automotive field, and industrial field, and belongs to these technical fields.

[0002] Acid-modified polyolefins, obtained by grafting organic acids having unsaturated double bonds onto low-polarity polyolefins, have a highly polar acid-modified moiety and a low-polarity polymer backbone. For this reason, acid-modified polyolefins are used as a primer for coating polyolefin resins such as polypropylene, which have traditionally been considered difficult to bond, and as a raw material for adhesives for bonding polyolefins to each other or to polar materials such as metals.

[0003] The typical battery packaging material used for laminated batteries has a three-layer structure centered around aluminum foil, with adhesive between each layer. The three layers are the substrate layer, which forms the outer surface of the laminated battery after assembly; the barrier layer, made of aluminum foil or stainless steel foil, which prevents the penetration of moisture and air; and the sealant layer, which insulates the barrier layer from contact with the electrodes and electrolyte and heat-seals the outer periphery. Each layer may consist of two or more layers. Of these, the sealant layer, which comes into contact with the electrolyte, is made of an olefin-based film such as polypropylene film, and the adhesive between the aluminum foil and the sealant layer is made of a polyurethane-based adhesive crosslinked with an acid-modified polymer, such as an acid-modified polyolefin or an acid-modified styrene-based elastomer, using an isocyanate-based crosslinking agent.

[0004] Among these, adhesives composed of acid-modified polyolefins and isocyanate-based crosslinkers have been widely used in recent years due to their high adhesive strength. For example, Patent Documents 1 and 2 describe packaging materials for battery cases in which an unstretched thermoplastic resin film layer and an aluminum foil layer are bonded via an adhesive layer containing a polyolefin resin having a carboxyl group and a polyfunctional isocyanate compound. As described in Patent Documents 1 and 2, such adhesives composed of acid-modified polyolefins and isocyanate-based crosslinkers are mainly used as adhesive solutions by dissolving them in a solvent. Battery packaging materials are produced by a dry lamination method in which the adhesive solution is applied to aluminum foil or a film for a sealant layer, dried, and then the aluminum foil and the film for a sealant layer are bonded together.

[0005] JP 2010-92703 A JP 2014-89985 A

[0006] When a laminate sheet is produced using the adhesives described in Patent Documents 1 and 2, there is a problem in that the curing speed differs between the center and edges of the sheet, and if the curing time is short, the adhesive strength in the center becomes low. This problem is particularly pronounced when the area of ​​the laminate sheet is large. An object of one embodiment of the present invention is to provide an adhesive composition that can quickly and firmly bond adherends at both the center and edges.

[0007] As a result of intensive research by the present inventors to solve the above problems, the present invention has been completed. Based on these findings, the present specification provides the following means.

[0008] [1] An adhesive composition containing an acid-modified polyolefin, a polyfunctional isocyanate compound, and a curing catalyst, wherein the ratio ([NCO] / [COOH]) of the total number of isocyanate groups [NCO] (unit: mole) possessed by the polyfunctional isocyanate compound to the total number of carboxy groups [COOH] (unit: mole) possessed by the acid-modified polyolefin is 7 to 40, and wherein the acid anhydride structure (-CO-O-CO-) contained in the acid-modified polyolefin is included in the total number of carboxy groups as 2 moles of carboxy groups per mole, and the curing catalyst contains Sn, and the content of Sn is 500 to 4000 ppm relative to the total weight of the acid-modified polyolefin and the polyfunctional isocyanate compound. [2] A two-component adhesive composition comprising a component A and a component B, wherein component A comprises an acid-modified polyolefin, component B comprises a polyfunctional isocyanate compound, and at least one of components A and B comprises a curing catalyst, wherein the ratio ([NCO] / [COOH]) of the total number of isocyanate groups [NCO] (unit: moles) possessed by the polyfunctional isocyanate compound to the total number of carboxy groups [COOH] (unit: moles) possessed by the acid-modified polyolefin is 7 to 40, with the proviso that the acid anhydride structure (-CO-O-CO-) contained in the acid-modified polyolefin accounts for 2 moles of carboxy groups per mole, and the curing catalyst contains Sn, with the Sn content being 500 to 4,000 ppm relative to the total weight of the acid-modified polyolefin and the polyfunctional isocyanate compound. [3] A cured product of the adhesive composition according to [1] or [2]. [4] A sheet-like laminate comprising an adhesive layer made of a cured product of the adhesive composition according to [1] or [2], wherein the laminate has an internal point that is 10 cm or more away from an edge, and the distance is the shortest distance from the edge that is closest to the internal point. [5] A sheet-like laminate comprising an adhesive layer made of a cured product of the adhesive composition according to [1] or [2], wherein the laminate has a width of 20 cm or more and a length of 1 m or more.[6] A heat-sealable member comprising an adhesive layer formed by curing the adhesive composition according to [1] or [2], a metal layer bonded to one side of the adhesive layer, and a heat-sealable resin layer bonded to the other side of the adhesive layer. [7] A packaging material for an electricity storage device comprising the heat-sealable member according to [5].

[0009] According to the present invention, an adhesive composition having improved adhesive properties at high temperatures can be obtained. The adhesive composition of the present invention is particularly suitable as a packaging material for an electricity storage device.

[0010] 1 is a schematic perspective view showing an example of the heat-sealable member of the present invention, and FIG. 2 is a schematic perspective view showing another example of the heat-sealable member of the present invention.

[0011] Hereinafter, embodiments for carrying out the present disclosure will be described in detail. However, the present disclosure is not limited to the following embodiments. In this specification, a numerical range indicated using "to" includes the numerical values ​​before and after "to" as the minimum and maximum values, respectively. In numerical ranges described in stages in this specification, the upper or lower limit value described in one numerical range may be replaced with the upper or lower limit value of another numerical range described in stages. Furthermore, in numerical ranges described in this specification, the upper or lower limit value of that numerical range may be replaced with a value shown in an example. Furthermore, two or more preferred embodiments in this specification can be combined, and combining them can result in a more preferred embodiment.

[0012] The adhesive composition of the present invention will be described below in terms of each of its constituent components. 1. Acid-modified polyolefin The acid-modified polyolefin is a polyolefin having a carboxy group and / or a carboxylic anhydride group. The acid-modified polyolefin is preferably a polyolefin modified with a carboxy group-containing monomer and / or a carboxylic anhydride group-containing monomer.

[0013] The modification may be carried out by a known method, for example, by graft modification in which a carboxyl group-containing monomer and / or a carboxylic anhydride group-containing monomer is added to a polyolefin in the presence of a known radical polymerization initiator such as an organic peroxide or an aliphatic azo compound in melt kneading or in an organic solvent, and copolymerization of a carboxyl group-containing monomer and / or a carboxylic anhydride group-containing monomer with an olefin.

[0014] Among these methods, acid-modified polyolefins are preferably produced by acid-modifying a radically graftable polyolefin with an unsaturated carboxylic acid anhydride. Radical-graftable polyolefins are polyolefins containing monomer units having hydrogen atoms that can be abstracted by radicals. Radical-graftable polyolefins are typically non-acid-modified polyolefins (i.e., polyolefins that do not contain carboxy groups or acid anhydride structures), but may be partially acid-modified, such as at the terminals, in some cases. In this specification, such radical-graftable polyolefins may also be referred to as "polyolefins before acid modification."

[0015] Specific examples of polyolefins capable of undergoing radical grafting reactions include those obtained by homopolymerizing or copolymerizing polymerizable monomers selected from the group consisting of olefins (preferably having 2 to 6 carbon atoms, more preferably having 2 to 4 carbon atoms), styrene, cycloolefins (preferably having 3 to 10 carbon atoms, more preferably having 5 to 8 carbon atoms), and combinations thereof. In particular, polyolefins obtained from polymerizable monomers that generate relatively stable tertiary carbon radicals are preferred, and among these, copolymers of propylene and 1-butene have good solubility in solvents such as toluene and cyclohexane, and also have high adhesive performance, making them suitable for use as solution-type adhesives.

[0016] In the copolymer of propylene and 1-butene, the copolymerization ratio of 1-butene [1-butene / (propylene + 1-butene)] is preferably 5 to 40 mol%, more preferably 10 to 30 mol%. If the copolymerization ratio of 1-butene is less than 5 mol%, the solubility in solvents is insufficient, and even if dissolved in a solvent by heating, the fluidity of the polyolefin solution is lost in a short time, making it impossible to apply the adhesive. If the copolymerization ratio of 1-butene exceeds 40 mol%, the hot adhesive properties are reduced.

[0017] The melting point of the radically graftable polyolefin is preferably 44°C or higher, more preferably 54°C or higher, particularly preferably 64°C or higher, and may be 74°C or higher. Within this range, the adhesive composition can obtain sufficient peel strength. The melting point of the radically graftable polyolefin is preferably 125°C or lower, more preferably 120°C or lower, particularly preferably 105°C or lower, and may be 95°C or lower. Within this range, sufficient storage stability at low temperatures can be obtained.

[0018] The unsaturated carboxylic acid anhydride is a carboxylic acid anhydride having at least one carbon-carbon double bond. The number of carbon atoms in the unsaturated carboxylic acid anhydride is usually 4 or more, and may be, for example, 5 or more or 6 or more. There is no particular upper limit on the number of carbon atoms in the unsaturated carboxylic acid anhydride, but the number of carbon atoms in the unsaturated carboxylic acid anhydride may be, for example, 10 or less or 8 or less.

[0019] Examples of the unsaturated carboxylic acid anhydride include acid anhydrides of unsaturated dicarboxylic acid compounds such as maleic anhydride, itaconic anhydride, citraconic anhydride, tetrahydrophthalic anhydride, nadic anhydride, and endic anhydride; and acid anhydrides of unsaturated tricarboxylic acid compounds such as aconitic anhydride. In particular, acid anhydrides having an acid anhydride structure and a five-membered ring consisting of a carbon-carbon bond are preferred.

[0020] As the unsaturated carboxylic acid anhydride, unsaturated dicarboxylic acid anhydrides are preferred because they are easily modified and have excellent adhesive properties, and specifically, maleic anhydride and itaconic anhydride are preferred.

[0021] These unsaturated carboxylic acid anhydrides may be used alone or in combination of two or more.

[0022] In the acid-modified polyolefin, a portion of the acid anhydride structures derived from the unsaturated carboxylic acid anhydride (for example, more than 0 mol % to 30 mol % or 5 mol % to 20 mol %, based on the total number of acid anhydride structures contained in the acid-modified polyolefin in the adhesive composition) may be hydrolyzed to carboxy groups. However, in order to extend the usable life, it is preferable that the acid anhydride structures are maintained.

[0023] The graft amount of unsaturated carboxylic acid anhydride in the acid-modified polyolefin can be confirmed by the amount of acid anhydride structure (—CO—O—CO—) present in the acid-modified polyolefin. The amount of acid anhydride structure is evaluated by its acid value. The acid value of the acid-modified polyolefin is preferably 1 mg KOH / g or more, more preferably 3 mg KOH / g or more, and even more preferably 5 mg KOH / g or more. When the acid value of the acid-modified polyolefin is within any of these ranges, high adhesive strength can be obtained. The acid value of the acid-modified polyolefin is preferably 60 mg KOH / g or less, more preferably 40 mg KOH / g or less, and even more preferably 20 mg KOH / g or less. When the acid value of the acid-modified polyolefin is within any of these ranges, the stability of the adhesive solution is improved. The acid value of the acid-modified polyolefin can be measured according to the method described in the Examples below.

[0024] The acid anhydride structures of the unsaturated carboxylic acid anhydride grafted onto the acid-modified polyolefin may all be hydrolyzed to carboxylic acids.

[0025] The acid-modified polyolefin may further be graft-modified with a (meth)acrylic acid alkyl ester. However, in one embodiment of the present invention, it may be preferable that the acid-modified polyolefin is not graft-modified with a (meth)acrylic acid alkyl ester. The (meth)acrylic acid alkyl ester is preferably an ester compound of an alkyl alcohol having 8 to 18 carbon atoms and (meth)acrylic acid (hereinafter referred to as a "(meth)acrylic acid long-chain alkyl ester"). The order in which the unsaturated carboxylic acid anhydride and the (meth)acrylic acid alkyl ester are grafted onto the polyolefin before acid modification is not particularly limited, and they may be graft-modified simultaneously or separately.

[0026] The melting point of the acid-modified polyolefin is preferably 40°C or higher, more preferably 50°C or higher, particularly preferably 60°C or higher, and may be 70°C or higher. Within such a range, the adhesive composition can obtain sufficient peel strength. The melting point of the acid-modified polyolefin is preferably 90°C or lower, more preferably 85°C or lower, particularly preferably 80°C or lower. When the melting point is within this range, the adhesive composition can be laminated at a low temperature, and thermal expansion of the adherend can be suppressed. The melting point can be measured in accordance with JIS K7121 using a differential scanning calorimeter (DSC) at a heating rate of 10°C / min.

[0027] The melt flow rate of the acid-modified polyolefin is preferably 50 g / 10 min or more, more preferably 100 g / 10 min or more. The melt flow rate of the acid-modified polyolefin is preferably 1000 g / 10 min or less, more preferably 800 g / 10 min or less. By setting the melt flow rate to 50 g / 10 min or more, the solution viscosity of the adhesive composition is reduced, and the coating speed can be improved. On the other hand, by setting the melt flow rate to 1000 g / 10 min or less, the hot peel strength can be further improved. The melt flow rate can be measured in accordance with JIS K7210 at a test temperature of 190°C and a test load of 2.17 kg.

[0028] The weight average molecular weight of the acid-modified polyolefin may be, for example, in the range of 15,000 to 200,000. From the viewpoint of improving peel strength and electrolyte resistance, the weight average molecular weight of the acid-modified polyolefin is preferably 15,000 or more, more preferably 30,000 or more. Furthermore, from the viewpoint of improving solubility in organic solvents, the weight average molecular weight of the acid-modified polyolefin is preferably 200,000 or less, more preferably 150,000 or less, and particularly preferably 100,000 or less. The weight average molecular weight is a value obtained by converting the molecular weight measured by gel permeation chromatography into polystyrene equivalent.

[0029] The content of the acid-modified polyolefin in the adhesive composition is preferably 30 to 90 wt %, and more preferably 40 to 80 wt %, relative to 100 wt % of the solids content of the adhesive composition, in terms of excellent hot peel strength and electrolyte resistance.

[0030] The radical graft reaction method of an acid-modified polyolefin is classified into two types. One is a method (thermal melting method) in which other reactive components are mixed into a thermally molten polyolefin capable of radical graft reaction and allowed to react. The other is a method (solution method) in which a solvent is used to mix and dissolve reactive components including a polyolefin capable of radical graft reaction in the solvent and allow to react. In the present embodiment, acid-modified polyolefins produced by either method can be preferably used.

[0031] If a portion of the unsaturated carboxylic acid anhydride used for the acid modification remains unreacted, it may be removed by a known method such as distillation by heating or reprecipitation purification, if necessary.

[0032] 2. Polyfunctional Isocyanate Compound The adhesive composition contains a polyfunctional isocyanate compound. The polyfunctional isocyanate compound is a compound having two or more isocyanate groups, and particularly preferably a compound having two isocyanate groups, and is capable of crosslinking the acid-modified polyolefin.

[0033] The polyfunctional isocyanate compound is not particularly limited, and various polyfunctional isocyanate compounds such as aromatic, aliphatic, and alicyclic polyfunctional isocyanate compounds can be used. Examples of the polyfunctional isocyanate compound include pentamethylene diisocyanate, hexamethylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, xylylene diisocyanate, hydrogenated xylylene diisocyanate, isophorone diisocyanate, and norbornane diisocyanate.

[0034] In this specification, the term "polyfunctional isocyanate compound" encompasses not only polyfunctional isocyanate compounds but also derivatives formed from polyfunctional isocyanate compounds. Derivatives of polyfunctional isocyanate compounds are compounds in which isocyanate groups are converted to isocyanurate bonds, biuret bonds, urethane bonds, allophanate bonds, urea bonds, uretdione bonds, or the like through chemical reactions. Compounds containing isocyanurate bonds are particularly preferred because they are highly effective in improving adhesion to adherends and can improve room-temperature peel strength and electrolyte resistance. The derivative may be one in which all isocyanate groups have been chemically converted, but is preferably one in which at least one isocyanate group remains unreacted.

[0035] The derivative may be formed from two or more of the same or different polyfunctional isocyanate compounds. Specific examples of such derivatives of polyfunctional isocyanate compounds include multimers of polyfunctional isocyanate compounds. Multimers of polyfunctional isocyanate compounds may be formed via the above-mentioned bonds, such as uretdione bonds, isocyanurate bonds, and allophanate bonds. The polyfunctional isocyanate compounds forming the multimer are usually all of the same type of polyfunctional isocyanate compound, but may also be different types of polyfunctional isocyanate compounds. The number of polyfunctional isocyanate compounds constituting the multimer is not particularly limited, and may be a multimer of a general isocyanate compound. Specifically, the multimer may be a dimer, trimer, tetramer, or the like.

[0036] In this specification, when a polyfunctional isocyanate compound is a derivative formed from different types of polyfunctional isocyanate compounds, the derivative is described as a derivative of any of the different types of polyfunctional isocyanate compounds. For example, a derivative formed from two different types of polyfunctional isocyanate compounds, i.e., a polyfunctional isocyanate compound (A) and a polyfunctional isocyanate compound (B), is a derivative of both the polyfunctional isocyanate compound (A) and the polyfunctional isocyanate compound (B).

[0037] In one embodiment of the present invention, the adhesive composition may contain two or more, particularly two, types of polyfunctional isocyanate compounds. By containing two or more types of polyfunctional isocyanate compounds, hot peel strength and electrolyte resistance can be improved.

[0038] Here, the two types of polyfunctional isocyanate compounds are referred to as polyfunctional isocyanate compound (1) and polyfunctional isocyanate compound (2). The polyfunctional isocyanate compound (1) and the polyfunctional isocyanate compound (2) are different compounds. One or both of the polyfunctional isocyanate compound (1) and the polyfunctional isocyanate compound (2) may be derivatives. When the adhesive composition contains a derivative of a polyfunctional isocyanate compound, the polyfunctional isocyanate compound (1) and the polyfunctional isocyanate compound (2) may form a single derivative, but it is preferable that the polyfunctional isocyanate compound (1) and the polyfunctional isocyanate compound (2) each independently form a single derivative.

[0039] In one embodiment of the present invention, the polyfunctional isocyanate compound (1) may be a polyfunctional isocyanate compound having a hydrocarbon group having 4 to 7 carbon atoms, particularly a diisocyanate compound, and the polyfunctional isocyanate compound (2) may be a polyfunctional isocyanate compound having a hydrocarbon group having 8 to 14 carbon atoms, particularly a diisocyanate compound.

[0040] In one embodiment of the present invention, the polyfunctional isocyanate compound (1) may be a polyfunctional isocyanate compound having an aliphatic hydrocarbon group, particularly a diisocyanate compound, and the polyfunctional isocyanate compound (2) may be a polyfunctional isocyanate compound having an alicyclic hydrocarbon group, particularly a diisocyanate compound. The number of carbon atoms in the aliphatic hydrocarbon group may be, for example, 1, 2, 3, 4, 5, 6, 7, 8, 9, or 10. The alicyclic hydrocarbon group is a hydrocarbon group containing an aliphatic ring, and the aliphatic ring may be linked to an aliphatic hydrocarbon group having, for example, 1 to 3 carbon atoms. As the aliphatic ring, a cyclohexane ring, a cyclopentane ring, or the like can be preferably used. The number of carbon atoms in the aliphatic ring may be, for example, 4, 5, 6, 7, 8, 9, or 10.

[0041] The weight ratio of the polyfunctional isocyanate compound (1) to the polyfunctional isocyanate compound (2) (polyfunctional isocyanate compound (1) / polyfunctional isocyanate compound (2)) is not particularly limited. In one embodiment, the weight ratio of the polyfunctional isocyanate compound (1) to the polyfunctional isocyanate compound (2) (polyfunctional isocyanate compound (1) / polyfunctional isocyanate compound (2)) is preferably within a range of 1 / 3 to 3 / 1, more preferably within a range of 1 / 2 to 2 / 1, and the weight of the polyfunctional isocyanate compound (1) and the weight of the polyfunctional isocyanate compound (2) may be the same.

[0042] Specific examples of polyfunctional isocyanate compounds having a hydrocarbon group having 4 to 7 carbon atoms include hexamethylene diisocyanate, pentamethylene diisocyanate, and tetramethylene diisocyanate.

[0043] Commercially available products can be used as derivatives of polyfunctional isocyanate compounds having a hydrocarbon group containing 4 to 7 carbon atoms. Commercially available products of compounds having an isocyanurate bond include Duranate TPA-100 (manufactured by Asahi Kasei Corporation), Duranate MFA-75B (manufactured by Asahi Kasei Corporation), Duranate TUL-100 (manufactured by Asahi Kasei Corporation), Duranate TSA-100 (manufactured by Asahi Kasei Corporation), Coronate HX (manufactured by Tosoh Corporation), and Takenate D-170N (manufactured by Mitsui Chemicals, Inc.). Commercially available products of compounds having a biuret bond include Duranate 24A-100 (manufactured by Asahi Kasei Corporation), Duranate 21S-75E (manufactured by Asahi Kasei Corporation), Takenate D-165NN (manufactured by Mitsui Chemicals, Inc.), and Desmodur N3200 (manufactured by Sumika Covestro Urethane Co., Ltd.). Commercially available compounds having a urethane bond include Duranate P301-75E (manufactured by Asahi Kasei Corporation), which is an adduct of hexamethylene diisocyanate and trimethylolpropane, and Sumidur HT (manufactured by Sumika Covestro Urethane Co., Ltd.). Commercially available compounds having an allophanate bond include Desmodur XP2580 (manufactured by Sumika Covestro Urethane Co., Ltd.).

[0044] Specific examples of polyfunctional isocyanate compounds having a hydrocarbon group having 8 to 14 carbon atoms include polyfunctional isocyanate compounds having one secondary isocyanate group, such as isophorone diisocyanate and norbornane diisocyanate, polyfunctional isocyanate compounds having two secondary isocyanate groups, such as 4,4'-methylenebis(cyclohexyl isocyanate), and polyfunctional isocyanate compounds having no secondary isocyanate groups, such as dodecane diisocyanate and 1,3-bis(isocyanatomethyl)cyclohexane.

[0045] Commercially available products can be used as derivatives of polyfunctional isocyanate compounds having a hydrocarbon group having 8 to 14 carbon atoms. Commercially available products of compounds having an isocyanurate bond include Desmodur Z4470 BA (manufactured by Sumika Covestro Urethane Co., Ltd.) and Duranate T4900-70B (manufactured by Asahi Kasei Corporation). Commercially available products of compounds having an allophanate bond include Desmodur XP2565 (manufactured by Sumika Covestro Urethane Co., Ltd.). Commercially available products of compounds having a urethane bond include Takenate D-140N (manufactured by Mitsui Chemicals, Inc.), which is an adduct of isophorone diisocyanate and trimethylolpropane, and VESTANAT EP-DC1241 (manufactured by Evonik Japan Co., Ltd.), which is a monoadduct of isophorone diisocyanate and hydroxyethyl acrylate.

[0046] The amount of polyfunctional isocyanate compound in the adhesive composition can be determined from the ratio ([NCO] / [COOH]) of the total number of isocyanate groups [NCO] (unit: mole) possessed by the polyfunctional isocyanate compound contained in the adhesive composition to the total number of carboxy groups [COOH] (unit: mole) possessed by the acid-modified polyolefin contained in the adhesive composition. The total number of carboxy groups in the acid-modified polyolefin is the total number of carboxy groups when each acid anhydride structure (—CO—O—CO—) present in the acid-modified polyolefin is considered to be two carboxy groups. To improve the peel strength of the adhesive composition, [NCO] / [COOH] is preferably 7 to 40, more preferably 7 to 30, and particularly preferably 7 to 26. A lower upper limit for [NCO] / [COOH] tends to provide better results. Within these ranges, [NCO] / [COOH] is preferably 7 to 23, more preferably 9 to 20, and particularly preferably 10 to 15. The total number of carboxy groups can be determined from the acid value according to the method described in the Examples below.

[0047] The amount of the polyfunctional isocyanate compound in the adhesive composition can also be determined by the weight ratio of the polyfunctional isocyanate compound to the total weight of the acid-modified polyolefin and the polyfunctional isocyanate compound (hereinafter also referred to as the polyfunctional isocyanate compound content). The polyfunctional isocyanate compound content is preferably 5 wt% or more, more preferably 10 wt% or more, and particularly preferably 30 wt% or more. The polyfunctional isocyanate compound content is preferably 60 wt% or less, more preferably 40 wt% or less.

[0048] 3. Curing catalyst The curing catalyst is blended to promote the crosslinking reaction between the acid-modified polyolefin and the polyfunctional isocyanate compound, thereby achieving excellent adhesive performance. The curing catalyst contains Sn. Examples of curing catalysts containing Sn include Sn carboxylates, Sn complex salts, and organic Sn compounds.

[0049] Examples of Sn carboxylates and complex salts include metal octanoates such as metal acetates, metal hexanoates, and metal 2-ethylhexanoates; metal carboxylates such as metal neodecanoates, metal laurates, metal stearates, and metal oleates; and Sn complex salts such as metal acetylacetonates. The organic Sn compound is not particularly limited as long as it is a Sn compound having a bond with carbon, and examples include Sn oxides. These may be used alone or in combination of two or more. Specific examples include dibutyltin dilaurate, dioctyltin dilaurate, dioctyltin diacetate, dibutyltin maleate, dibutyltin oxide, and dioctyltin oxide.

[0050] The content of the curing catalyst is preferably 0.001 to 5 parts by weight per 100 parts by weight of the total amount of the acid-modified polyolefin and the polyfunctional isocyanate compound. By setting the content of the curing catalyst to 0.001 parts by weight or more, the catalytic effect is easily obtained, and by setting the content of the curing catalyst to 5 parts by weight or less, the storage stability of the adhesive composition can be ensured. The content of the curing catalyst is determined by the weight ratio of Sn relative to the total weight of the acid-modified polyolefin and the polyfunctional isocyanate compound. The weight ratio of Sn relative to the total weight of the acid-modified polyolefin and the polyfunctional isocyanate compound is 500 to 4000 ppm, more preferably 1000 to 3000 ppm, and particularly preferably 1500 to 2500 ppm. The weight ratio of Sn (unit: ppm) is calculated using the following formula: Weight ratio of Sn (unit: ppm) = Weight of Sn / Total weight of acid-modified polyolefin and polyfunctional isocyanate compound × 10 ６ By having the Sn weight ratio within the above range, the formation of biuret bonds due to the reaction between polyfunctional isocyanate compounds, the reaction between the acid-modified polyolefin and the polyfunctional isocyanate compound, and the reaction between the carboxy group generated by hydrolysis of the carboxylic anhydride group of the acid-modified polyolefin and the polyfunctional isocyanate are promoted, thereby rapidly curing the adhesive composition. As a result, high adhesive strength can be obtained even in the center of the resulting laminate. After the adhesive composition is cured, the weight ratio of Sn contained in the cured product is preferably 500 to 4000 ppm, more preferably 1000 to 3000 ppm, and particularly preferably 1500 to 2500 ppm.

[0051] 4. Solvent The adhesive composition may contain an organic solvent that dissolves the acid-modified polyolefin. Specific examples of the organic solvent include aromatic organic solvents such as toluene and xylene, aliphatic organic solvents such as n-hexane, alicyclic organic solvents such as cyclohexane, methylcyclohexane, and ethylcyclohexane, ketone organic solvents such as acetone and methyl ethyl ketone, alcohol organic solvents such as methanol and ethanol, ester organic solvents such as ethyl acetate and butyl acetate, and propylene glycol ether organic solvents such as propylene glycol methyl ether, propylene glycol ethyl ether, and propylene glycol t-butyl ether.

[0052] In the adhesive composition of the present invention, the organic solvent may be used alone or in combination of two or more kinds.

[0053] Among these, the organic solvent is preferably a mixed solvent containing an alicyclic organic solvent and a ketone organic solvent. A mixed solvent of an alicyclic organic solvent and a ketone organic solvent can adequately dissolve a polyfunctional isocyanate compound and improve the hot peel strength of a cured product of the adhesive composition of the present invention. The total content of the alicyclic organic solvent and the ketone organic solvent in the mixed solvent is preferably 80% by weight or more, more preferably 90% by weight or more, and may even be 100% by weight. The weight ratio of the alicyclic organic solvent to the ketone organic solvent in the mixed solvent (weight of the alicyclic organic solvent / weight of the ketone organic solvent) is preferably 8 / 2 or less, more preferably 7 / 3 or less, and particularly preferably 6 / 4 or less. The weight ratio of the alicyclic organic solvent to the ketone organic solvent in the mixed solvent (weight of the alicyclic organic solvent / weight of the ketone organic solvent) is preferably 2 / 8 or more, more preferably 3 / 7 or more, and particularly preferably 4 / 6 or more.

[0054] The amount of solvent in the adhesive composition is not particularly limited and may be determined appropriately depending on the types of acid-modified polyolefin and polyfunctional isocyanate compound, etc. When the total of the acid-modified polyolefin and the solvent is taken as 100% by weight, the amount of the acid-modified polyolefin is preferably 5 to 40% by weight, more preferably 10 to 30% by weight. When the solvent is present in the adhesive composition in such an amount, the adhesive composition can be easily applied to an adherend, and workability is excellent.

[0055] 5. Additional Components The adhesive composition may further contain additional components depending on the intended purpose. Specific examples of the additional components include thermoplastic resins, tackifiers, antioxidants, hindered amine light stabilizers, ultraviolet absorbers, antistatic agents, flame retardants, colorants, dispersants, adhesion promoters, antifoaming agents, leveling agents, plasticizers, lubricants, crystal nucleating agents, and fillers.

[0056] These components are described below. The additional components are optional components, and may not be used, or only one type may be used, or two or more types may be used in combination.

[0057] A thermoplastic resin such as a styrene-based thermoplastic elastomer can be blended into the adhesive composition to improve adhesive strength. In one embodiment of the present invention, the adhesive composition does not need to contain any thermoplastic resin other than the acid-modified polyolefin.

[0058] Specific examples of styrene-based thermoplastic elastomers include styrene-based resins such as styrene-butadiene copolymer, epoxy-modified styrene-butadiene copolymer, styrene-butadiene-styrene block copolymer, styrene-ethylene / propylene-styrene block copolymer (hereinafter referred to as "SEPS"), styrene-ethylene / butylene-styrene block copolymer (hereinafter referred to as "SEBS"), styrene-isoprene / butadiene-styrene block copolymer, and styrene-isoprene-styrene block copolymer, and these may be those which do not have acidic groups and acid anhydride groups, or those which have acidic groups and / or acid anhydride groups, or those which have amino groups.

[0059] As the tackifier, known ones can be used, and examples thereof include polyterpene resins, rosin resins, aliphatic petroleum resins, alicyclic petroleum resins, copolymer petroleum resins, and hydrogenated petroleum resins.

[0060] The content of the tackifier is preferably 1 to 20% by weight, and more preferably 1 to 10% by weight, relative to 100% by weight of the adhesive composition, in order to provide excellent hot water resistance.

[0061] 6. Adhesive Composition The adhesive composition can be produced by a known method. Specifically, a solution obtained by dissolving an acid-modified polyolefin in a solvent is mixed with the other components except the polyfunctional isocyanate compound, and then the resulting mixture is mixed with the polyfunctional isocyanate compound. The temperature during mixing is typically 40°C or less, preferably 10°C to 30°C. The adhesive composition may be a two-component adhesive composition consisting of component A and component B. The adhesive composition can be used as an adhesive composition by mixing component A and component B immediately before use. The components of component A and component B are the same as those of the adhesive composition, and by blending the components in component A and component B, storage stability can be improved. For example, component A may contain an acid-modified polyolefin, component B may contain a polyfunctional isocyanate compound, and at least one of component A and component B may contain a curing catalyst. In such a configuration, component A preferably does not contain a polyfunctional isocyanate compound, and component B preferably does not contain an acid-modified polyolefin.

[0062] 7. Adhesive Laminate An adhesive laminate can be produced by bonding two adherends using the adhesive composition. The adhesive laminate may be a laminate film. The adhesive composition can bond even large adherends with high adhesive strength. Therefore, the adhesive composition is suitable for producing large laminates. The size of the laminate is preferably 10 cm or more in width, preferably 20 cm or more in width, and particularly preferably 25 cm or more in width. The size of the laminate may be 30 cm or more in length. The size of the laminate is preferably 50 cm or more in length, more preferably 1 m or more in length, and particularly preferably 2 m or more in length. There is no upper limit to the size of the laminate, but it may be, for example, 5 m or less in width and 50 m or less in length. The longer the shortest distance from the edge to the center of the laminate, the more pronounced the effect of the adhesive composition can be. The distance from the edge of the laminate to any point inside is preferably 5 cm or more, more preferably 10 cm or more, particularly preferably 13 cm or more, and may even be 15 cm or more. There is no particular upper limit to the shortest distance, but it may be, for example, 1 m or less. Here, the distance from the edge of the laminate to an internal point is the shortest distance from the nearest edge. The internal point may be selected arbitrarily, but is preferably selected so that the shortest distance is the longest. Use of the adhesive composition can impart high adhesive strength to both the edge and the internal of the laminate. The presence of an internal point at such a distance can make the effect of the adhesive composition more pronounced. The shape of the laminate is not particularly limited. In the case of a laminate film, since it is produced by laminating films, the shape of the laminate may be rectangular. The shape of the corners of a rectangular laminate may be changed by chamfering, or it may be processed into a circular or elliptical shape.

[0063] 8. Heat-sealable member A heat-sealable member can be produced using the adhesive composition. The heat-sealable member includes an adhesive layer formed by curing the adhesive composition of the present invention, a metal layer bonded to one side of the adhesive layer, and a heat-sealable resin layer bonded to the other side of the adhesive layer.

[0064] Schematic diagrams of heat-sealable members are shown in Figures 1 and 2. That is, the heat-sealable member 1 in Figure 1 sequentially comprises a heat-sealable resin layer 11, an adhesive layer 12, and a metal layer 13. Also, the heat-sealable member 1 in Figure 2 sequentially comprises a heat-sealable resin layer 11, an adhesive layer 12, a metal layer 13, and another layer 14.

[0065] The shape of the heat-sealable member may be appropriately determined depending on the application, etc., and is not particularly limited, but examples thereof include a film, a sheet, and a plate.

[0066] The heat-sealable resin layer is a layer containing a resin that melts with heat and can fuse the material constituting one layer with the material constituting the other layer. This heat-sealable resin layer is preferably a layer containing a resin that melts at a temperature of 50°C to 200°C. Examples of resins having such properties include polyolefin resins, polyamide resins, and polyester resins. Among these, polyolefin resins are preferred because they can be heat-sealed with sufficient strength. Furthermore, polypropylene is a preferred polyolefin resin. In particular, unstretched polypropylene is more preferred because it undergoes little dimensional change (shrinkage) when the heat-sealable member is used to integrate with other members.

[0067] The above-mentioned heat-fusible resin layer may be a layer containing additives such as a lubricant, a filler, a heat stabilizer, an antioxidant, an ultraviolet absorber, an antistatic agent, a flame retardant, a colorant, a dispersant, and an adhesion imparting agent, as necessary.

[0068] The thickness of the heat-sealable resin layer is not particularly limited and depends on the resin material, etc., but for example, in the case of a layer containing unstretched polypropylene, it is preferably 10 to 200 μm, more preferably 20 to 100 μm. If the thickness of the layer containing unstretched polypropylene is 10 to 200 μm, it is possible to obtain a heat-sealed composite product such as a sealed container that is not easily broken and has high durability.

[0069] The adhesive layer is a layer formed by curing the adhesive composition. The thickness of the adhesive layer is not particularly limited, but is preferably 1 to 20 μm, and particularly preferably 2 to 10 μm. If the thickness of the adhesive layer is 1 to 20 μm, the heat-fusible member can be easily processed, for example, by folding, when the member is in the form of a sheet.

[0070] The metal layer is a layer containing a metal or an alloy. Examples of metals or alloys include aluminum, iron, titanium, magnesium, copper, nickel, chromium, and other metals, as well as alloys thereof. Among these, aluminum is preferred due to its excellent workability. The thickness of the metal layer is not particularly limited, depending on the material and other factors. When the metal layer is made of aluminum, for example, it is preferably 20 to 100 μm, particularly preferably 20 to 80 μm, and even more preferably 30 to 60 μm.

[0071] When the heat-sealable member includes a metal layer, another layer 14 may be provided on the surface of the metal layer 13, as shown in FIG. 2 . The material constituting the other layer preferably includes a resin to protect the metal layer. That is, the other layer is preferably a resin layer. This resin is not particularly limited and can be polyamide resin, polyester resin, or the like. The transparency of the resin layer is not particularly limited, but if this resin layer is transparent or translucent, it can achieve an excellent appearance when used as a heat-sealable composite product, such as a sealed container. The other layer may have a multilayer structure and may, for example, include an adhesive layer for bonding the resin layer and the metal layer. The adhesive layer in the other layer may be the same as or different from the adhesive layer provided between the heat-sealable resin layer and the metal layer. The thickness of the other layer is not particularly limited and is preferably 30 to 60 μm, particularly preferably 30 to 50 μm.

[0072] Heat-fusible parts using the adhesive composition of the present invention have high hot peel strength and excellent adhesion, and also have excellent resistance to solvents such as electrolytes, so they can prevent deterioration of the contents while maintaining their structure.

[0073] When used in lithium-ion battery packaging materials, the adhesive performance can be maintained even if there are temperature changes in the battery storage or usage environment, and in particular, the adhesive performance can be maintained in a temperature range higher than normal temperature in summer or inside a car, etc., and a temperature range lower than the ambient temperature in cold regions, due to the chemical temperature rise of the battery constituent materials that accompanies charging or discharging.

[0074] 9. Manufacturing Methods of Heat-Fusible Members The manufacturing methods of the heat-fusible member shown in Fig. 1 are as follows: (1) A method in which an adhesive composition is applied to the surface of a metal foil or the like for forming the metal layer 13, the organic solvent in the composition is then removed to form the adhesive layer 12, and then a resin film for forming the heat-fusible resin layer 11 (hereinafter referred to as a "heat-fusible resin film") is brought into contact with the surface on which the adhesive layer 12 has been formed, and pressure-bonded while heating. (2) A method in which an adhesive composition is applied to the surface of a heat-fusible resin film, the organic solvent in the composition is then removed to form the adhesive layer 12, and then a metal foil or the like for forming the metal layer 13 is brought into contact with the surface on which the adhesive layer 12 has been formed, and pressure-bonded while heating.

[0075] The heat-sealable member shown in Fig. 2 can be produced by the following methods: (3) applying an adhesive composition to the surface of the metal layer 13 of a composite film having a resin layer constituting the other layer 14 and a metal layer 13 formed on one side of the resin layer by lamination, vapor deposition, or the like, followed by removing the organic solvent from the composition to form an adhesive layer 12, and then contacting the surface on which the adhesive layer 12 is formed with a heat-sealable resin film and bonding them under pressure while heating; (4) applying an adhesive composition to the surface of a heat-sealable resin film and then removing the organic solvent from the composition to form an adhesive layer 12, followed by contacting the surface on which the adhesive layer 12 is formed with the surface on which the metal layer 13 is formed of a composite film having a resin layer constituting the other layer 14 and a metal layer 13 formed on one side of the resin layer by lamination, vapor deposition, or the like, followed by bonding them under pressure while heating; (5) extruding a film for forming the other layer 14 onto the surface of the metal layer 13 of a laminate obtained by the method (1) or (2) above.

[0076] The adhesive composition is often applied to a metal layer-forming material such as a metal foil, or to the surface of a metal layer in a composite film comprising a metal layer and another layer (resin layer), but is not particularly limited thereto. When using a metal foil, it is preferable to use an aluminum foil having a thickness of 20 to 100 μm. This makes it possible to easily form a heat-sealable member with reduced breakage. When using a composite film, it is preferable that the metal layer contains aluminum and that the other layer (resin layer) contains a polyamide resin, a polyester resin, or the like. Furthermore, when producing the heat-sealable member shown in FIG. 2 without using a composite film, i.e., when using the method (5) above, it is preferable to use a film containing a polyamide resin, a polyester resin, or the like as the film for forming the other layer 14.

[0077] Examples of heat-sealable resin films that can be used include polyolefin resin films, polyamide resin films, and polyester resin films. These resin films can be obtained by film-forming methods such as extrusion, cast molding, T-die molding, and inflation molding. The thickness of the heat-sealable resin film is typically 10 to 200 μm. In the present invention, polyolefin resin films are preferred because they facilitate heat-sealing to complete heat-sealable components and heat-sealing when producing heat-sealed composite products. Unstretched polypropylene films are particularly preferred because they can produce heat-sealed composite products such as sealed containers that are resistant to breakage and have excellent durability. When using unstretched polypropylene films, the preferred thickness is 10 to 200 μm, and more preferably 20 to 100 μm.

[0078] The adhesive composition can be applied by a conventionally known method, for example, using a bar coater, a gravure coater, or the like. The thickness of the coating film and the drying temperature thereof are not particularly limited. The drying temperature of the coating film is not particularly limited, but is preferably 30°C to 150°C from the viewpoint of workability.

[0079] As described above, the dried coating film generally has tackiness and adhesiveness, and therefore can bond two members together without heating, but when producing a heat-sealable member, a method of heating to an appropriate temperature while pressing can be applied, taking into consideration the melting point and melt viscosity of the acid-modified polyolefin, etc. Heating and pressing conditions include, for example, a temperature of 60 to 100°C, a pressure of 0.3 MPa, and a pressing time of 2 seconds.

[0080] Furthermore, the conditions for accelerating the crosslinking reaction between the acid-modified polyolefin and the polyfunctional isocyanate compound and completing the heat-fusible member (hereinafter referred to as "aging conditions") are not particularly limited, and are preferably set depending on the material of the metal foil and the material of the heat-fusible resin film, the melting temperature, the composition of the adhesive layer, etc. Examples of aging conditions include heating at 25 to 80°C, for example 40°C, for about 3 to 7 days.

[0081] 10. Applications The heat-sealable member can be used in a variety of industrial product fields, including electrical, automotive, industrial and other fields.

[0082] Examples of applications in the electrical field include packaging materials for secondary batteries such as lithium-ion batteries and lithium-ion polymer batteries, as well as for power storage devices such as capacitors; decoration by attaching decorative sheets to mobile devices, television housings, and white goods housings; adhesion between metal members and resins; and sealing of electronic components.

[0083] Examples of applications in the automotive field include bonding of metal / resin exterior materials in interior and exterior components such as pillars, moldings, door trims, spoilers, and roofs, as well as bonding genuine leather, fabrics, instrument panel foam sheets, and decorative sheets to substrates.

[0084] Examples of industrial applications include industrial packaging materials and inter-film bonding in multi-layer films such as barrier films.

[0085] Other applications include adhesion of logistics materials, building materials, daily necessities, and sporting goods.

[0086] Among these, the heat-sealable member is preferably used as a packaging material for an electricity storage device because it has high hot peel strength, excellent adhesiveness, and high electrolyte resistance.

[0087] In the tables shown below, the raw materials of the adhesive compositions may be indicated by abbreviations, and the abbreviations have the following meanings.

[0088] (Acid-modified polyolefin) Acid-modified polyolefin A: Acid-modified polyolefin produced as follows: In a 1 L autoclave, 100 parts by weight of propylene-butene copolymer (Mitsui Chemicals, Inc. "TAFMER (registered trademark) XM7070"), 150 parts by weight of toluene, 11 parts by weight of maleic anhydride, and 2 parts by weight of di-tert-butyl peroxide were added, and the mixture was heated to 140 ° C. and stirred for 3 hours. The resulting reaction solution was cooled to 100 ° C. and poured into a container containing 717 parts by weight of toluene and 950 parts by weight of methyl ethyl ketone preheated to 40 ° C. with stirring, cooled to 40 ° C., further stirred for 30 minutes, and further cooled to 25 ° C. to precipitate a resin. Thereafter, the slurry containing the resin was centrifuged to separate the acid-modified propylene-butene copolymer, maleic anhydride, and low molecular weight substances. Furthermore, the acid-modified propylene-butene copolymer extracted by centrifugation was poured into a new container containing 2,000 parts by weight of methyl ethyl ketone that had been kept warm at 25°C, and stirring was continued for 1 hour. The slurry was then centrifuged to further separate the acid-modified propylene-butene copolymer from maleic anhydride and low-molecular-weight substances. This operation was repeated twice for purification. After purification, the mixture was dried under reduced pressure at 40°C for 5 hours to obtain acid-modified polyolefin A. The obtained acid-modified polyolefin A had an acid value of 18 mgKOH / g, a melting point of 70°C, and a weight-average molecular weight of 79,000.

[0089] Acid-modified polyolefin B: Acid-modified polyolefin produced as follows: Acid-modified polyolefin B was obtained in the same manner as Acid-modified polyolefin A, except that the raw polyolefin was changed to a propylene-butene copolymer ("TAFMER (registered trademark) XM7070" manufactured by Mitsui Chemicals, Inc.), the amount of maleic anhydride was changed to 6 parts by weight, and the amount of di-tert-butyl peroxide was changed to 1 part by weight. The obtained Acid-modified polyolefin B had an acid value of 10 mgKOH / g, a melting point of 73°C, and a weight-average molecular weight of 91,000.

[0090] Acid-modified polyolefin C: An acid-modified polyolefin produced as follows: 1,000 parts by weight of a propylene-butene copolymer (Tafmer XM7070 manufactured by Mitsui Chemicals, Inc.), 15 parts by weight of maleic anhydride, 40 parts by weight of lauryl methacrylate, and 15 parts by weight of 2,5-dimethyl-2,5-di(t-butylperoxy)hexane were added to a twin-screw extruder with an L / D ratio of 42 and a diameter of 58 mm. The mixture was allowed to react for 10 minutes at a barrel temperature of 180°C (barrels 1 to 7). The mixture was degassed in the seventh barrel, and any remaining unreacted material was removed to obtain acid-modified polyolefin C. The resulting acid-modified polyolefin C had an acid value of 13 mg KOH / g, a melting point of 76°C, and a weight-average molecular weight of 140,000.

[0091] Acid-modified polyolefin D: Acid-modified polyolefin produced as follows: Acid-modified polyolefin D was obtained in the same manner as Acid-modified polyolefin C, except that the propylene-butene copolymer was changed to Tafmer XM7080 manufactured by Mitsui Chemicals, Inc. The obtained Acid-modified polyolefin D had an acid value of 15 mg KOH / g, a melting point of 84°C, and a weight-average molecular weight of 150,000. The graft weight of lauryl methacrylate in Acid-modified polyolefin D was 3.8% by weight, and the graft weight of maleic anhydride was 1.3% by weight.

[0092] The acid values, melting points, and weight average molecular weights of the acid-modified polyolefins A to D are summarized in Table 1 below.

[0093]

[0094] The acid value, melting point, and weight-average molecular weight of acid-modified polyolefins A to D were measured according to the method described below. (Acid Value Measurement) (1) 35 g of non-acid-modified resin (propylene butene copolymer) and octadecyl succinic anhydride (no additives, 1 g, 2 g, 4 g) were weighed out and placed in a Laboplastomill (manufactured by Toyo Seiki Seisaku-sho, Ltd.) heated to 170°C. The mixture was heated and stirred to produce four samples with different octadecyl succinic anhydride contents. (2) A small amount of each sample was cut out, sandwiched between two 1 mm-thick fluororesin sheets, and pressed in a hot press at 110°C to form a film. This film was vacuum-dried at 130°C for 5 hours to close the acid anhydride ring 100%. After cooling to room temperature, it was placed in a moisture-proof bag with a desiccant and sealed. It was then left at room temperature for at least one day, and its infrared absorption spectrum was measured by a transmission method. (3) From the transmission IR spectra of the four samples, approximately 1165 cm －１ Absorption (resin-derived peak) at about 1799 cm －１ A calibration curve was created by plotting the absorbance ratio of the absorption (peak derived from the acid anhydride) and the octadecyl succinic anhydride content. (4) Acid-modified polyolefins A to D were each vacuum dried at 130°C for 5 hours to close the acid anhydride ring 100%, cooled to room temperature, and then left in a dry state for at least one day before measuring the infrared absorption spectrum by a transmission method. (5) From the spectrum measured in (4), the peak at 1165 cm －１ Absorption at 1799 cm －１ The absorbance ratio was calculated and compared with the calibration curve prepared in (3) to determine the acid value.

[0095] (Measurement of Melting Point) The melting point was measured in accordance with JIS K7121 (2012). Specifically, the melting point was determined from the temperature at which the secondary temperature rise in the heat flux curve obtained using a differential scanning calorimeter becomes minimal. The heat flux curve was obtained by cooling approximately 10 mg of a sample to -50°C and holding it for 5 minutes, heating it to 150°C at 10°C / min and holding it for 5 minutes, cooling it to -50°C at 10°C / min and holding it for 5 minutes, then heating it to 150°C at 10°C / min and holding it for 5 minutes, and cooling it to -50°C at 10°C / min. Apparatus: DSC6220 manufactured by SII Nanotechnology Inc. Measurement atmosphere: Nitrogen atmosphere

[0096] (Measurement of Weight-Average Molecular Weight) The weight-average molecular weight of the acid-modified polyolefin was determined in terms of polystyrene using gel permeation chromatography (GPC). The apparatus and conditions used for the measurement were as follows: Apparatus: Model "HLC-8320" manufactured by Tosoh Corporation Column: TSKgel-SuperMultipore HZ-M (4.6 mm ID x 15 cm) x 3 manufactured by Tosoh Corporation Solvent: Tetrahydrofuran Column temperature: 40°C Detector: RI (differential refractive index detector) Flow rate: 350 μL / min

[0097] (Curing catalyst) DOTL: dioctyltin dilaurate DBTL: dibutyltin dilaurate

[0098] (Polyfunctional isocyanate compounds) TPA-100: Polyisocyanate of hexamethylene diisocyanate, manufactured by Asahi Kasei Corporation, "Duranate TPA-100" Z4470 BA: Polyisocyanate of isophorone diisocyanate, manufactured by Sumika Covestro Urethane Co., Ltd., "Desmodur Z4470BA" W: Dicyclohexylmethane-4,4'-diisocyanate, manufactured by Sumika Covestro Urethane Co., Ltd., "Desmodur W"

[0099] Example 1 (Preparation of Adhesive Solution) 15 g of acid-modified polyolefin A and 85 g of a mixed solvent of methylcyclohexane:methyl ethyl ketone = 51:34 (weight ratio) were weighed into a four-neck flask equipped with a condenser and a stirring motor, and the flask was immersed in an oil bath under a dry nitrogen stream and heated to 70°C while stirring until the acid-modified polyolefin A was completely dissolved, and then cooled to room temperature. To this was added the entire amount of a solution prepared by stirring and mixing 9 g of a polyfunctional isocyanate compound (TPA-100) and 0.09 g of dioctyltin dilaurate as a catalyst, and the mixture was stirred to prepare an adhesive solution. In the adhesive solution, the molar equivalent ratio (NCO / COOH) of the isocyanate groups to the carboxy groups in the acid-modified polyolefin was 10.8.

[0100] (Preparation of Test Pieces for Peel Strength Evaluation) The adhesive solution was applied using a bar coater to a 300 mm wide, 20 m long, and 40 μm thick aluminum foil that had been chemically treated on the adhesive-coated surface. The bar coater was selected in advance so that the average adhesive thickness after drying would be 2 to 4 μm. The aluminum foil was dried for 1 minute in an oven heated to 80°C, and an 80 μm thick CPP (cast polypropylene) film that had been corona discharge-treated on the surface that contacted the adhesive was overlaid. The film was sandwiched between a roll laminator at a roll temperature of 80°C and laminated. The film was then wound onto a 3-inch paper tube and rolled into a roll. This film was aged in a 40°C oven for 1 week to allow the curing reaction to proceed. After aging, a test piece was prepared from a section 2 m from the leading edge of the laminate film. A section 10 mm from the widthwise end was cut out to a width of 15 mm and a length of 200 mm in the MD direction to prepare a test piece at the end. A test piece of the central portion was cut out from a portion 150 mm from the end in the width direction, with a width of 15 mm and a length of 200 mm in the MD direction.

[0101] (Measurement of Peel Strength) Using a tensile tester equipped with a thermostatic chamber (Autograph AGS-X manufactured by Shimadzu Corporation), a T-peel test was performed at a pulling rate of 100 mm / min until the gripper of the test piece moved 100 mm, and the peel strength was determined by averaging the peel strength over a moving distance of 40 mm to 100 mm. The peel test was performed at room temperature (23°C). The peel test was performed on both the end test pieces and the central test pieces, and the results are shown in Table 2.

[0102] Examples 2 to 16 and Comparative Examples 1 to 7 The formulations of the other examples and comparative examples were those summarized in Tables 2 and 3, and test pieces for evaluating peel strength were prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Tables 2 and 3.

[0103]

[0104] In Tables 2 and 3, the Sn content is the ratio (ppm) of the weight of Sn to the total weight of the acid-modified polyolefin and the polyfunctional isocyanate compound.

[0105] The disclosures of Japanese Patent Application No. 2023-144637, filed September 6, 2023, and Japanese Patent Application No. 2024-030926, filed March 1, 2024, are incorporated herein by reference in their entirety. All publications, patent applications, and technical standards mentioned herein are incorporated herein by reference to the same extent as if each individual publication, patent application, and technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. An adhesive composition comprising an acid-modified polyolefin, a polyfunctional isocyanate compound and a curing catalyst, wherein the ratio ([NCO] / [COOH]) of the total number of isocyanate groups [NCO] (unit: mole) possessed by the polyfunctional isocyanate compound to the total number of carboxy groups [COOH] (unit: mole) possessed by the acid-modified polyolefin is 7 to 40, and an acid anhydride structure (-CO-O-CO-) contained in the acid-modified polyolefin is included in the total number of carboxy groups as 2 moles per mole, and the curing catalyst contains Sn, and the Sn content is 500 to 4000 ppm based on the total weight of the acid-modified polyolefin and the polyfunctional isocyanate compound.

2. A two-component adhesive composition comprising components A and B, wherein component A comprises an acid-modified polyolefin, component B comprises a polyfunctional isocyanate compound, and at least one of components A and B comprises a curing catalyst, the ratio ([NCO] / [COOH]) of the total number of isocyanate groups [NCO] (unit: mole) possessed by the polyfunctional isocyanate compound to the total number of carboxy groups [COOH] (unit: mole) possessed by the acid-modified polyolefin is 7 to 40, with the proviso that an acid anhydride structure (-CO-O-CO-) contained in the acid-modified polyolefin is included in the total number of carboxy groups as 2 moles per mole, and the curing catalyst comprises Sn, and the Sn content is 500 to 4000 ppm based on the total weight of the acid-modified polyolefin and the polyfunctional isocyanate compound.

3. A cured product of the adhesive composition according to claim 1 or 2.

4. A sheet-like laminate comprising an adhesive layer made of the cured product of the adhesive composition according to claim 1 or 2, wherein there is an internal point in the laminate that is 10 cm or more away from an end, and said distance is the shortest distance from the end closest to said internal point.

5. A heat-sealable component comprising an adhesive layer formed by curing the adhesive composition according to claim 1 or 2, a metal layer bonded to one side of the adhesive layer, and a heat-sealable resin layer bonded to the other side of the adhesive layer.

6. A packaging material for an electricity storage device, comprising the heat-sealable member according to claim 5.

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