Adhesive composition, bonding film, laminate equipped with adhesive layer, electromagnetic shield material, and laminate

Abstract

An adhesive composition (100) comprises: a polyester resin (A) that includes an ester bond which bonds repeating units together and one or more functional groups selected from the group consisting of carboxy groups and carboxylic acid anhydride structures; an epoxy compound (B) in the amount of 1-50 parts by mass with respect to 100 parts by mass of the polyester resin (A); and a cyclic carbodiimide (C) in the amount of 0.1-20 parts by mass with respect to 100 parts by mass of the polyester resin (A).

Description

Adhesive composition, bonding film, laminate with adhesive layer, electromagnetic wave shielding material and laminate

[0001] The present invention relates to an adhesive composition, a bonding film, a laminate with an adhesive layer, an electromagnetic wave shielding material, and a laminate.

[0002] Flexible printed circuit boards (hereinafter referred to as "FPCs") are capable of three-dimensional, high-density mounting even in limited spaces, and their applications are expanding. In recent years, as electronic devices have become smaller and lighter, FPC-related products have become more diverse and demand for them has increased.

[0003] Examples of such FPC-related products include flexible copper-clad laminates made by bonding a polyimide film and copper foil together, flexible printed wiring boards in which an electronic circuit is formed on a flexible copper-clad laminate, flexible printed wiring boards with reinforcement plates made by bonding a flexible printed wiring board and a reinforcement plate together, multilayer boards made by stacking and bonding flexible copper-clad laminates or flexible printed wiring boards, and flexible flat cables (hereinafter also referred to as "FFCs") in which copper wiring is bonded to a base film, and adhesives are usually used in the production of these products.

[0004] Furthermore, when manufacturing FPCs and FPC-related products, a laminate with an adhesive layer called a "coverlay film" is sometimes used to protect the wiring portion. The coverlay film comprises an insulating base film and an adhesive layer formed on the surface of the insulating base film, and polyimide resin is widely used as the material for the base film. Then, for example, a flexible printed wiring board is manufactured by attaching the coverlay film via the adhesive layer to the surface having the wiring portion using a heat press or the like.

[0005] Also known as printed wiring boards are build-up multilayer printed wiring boards in which conductor layers and organic insulating layers are alternately laminated on the surface of a substrate. An insulating adhesive layer is interposed between the conductor layer and the organic insulating layer in the multilayer printed wiring board, and the conductor layer and the organic insulating layer are bonded via the insulating adhesive layer. A sheet made of an uncured or semi-cured adhesive called a "bonding film" is used to form the insulating adhesive layer.

[0006] Furthermore, in order to reduce electromagnetic noise entering the printed wiring board from the outside or generated by the printed wiring board, an electromagnetic wave shielding material is sometimes applied to the surface of the printed wiring board. This type of electromagnetic wave shielding material has one or more layers including an adhesive layer, and at least one of the layers constituting the electromagnetic wave shielding material is conductive.

[0007] As an adhesive used in the production of FPCs and related products, for example, Patent Document 1 describes a curable composition containing (a) a polyester polymer containing two or more carboxyl groups in the molecule, having a number average molecular weight of 5,000 to 100,000, and a molecular weight per carboxyl group of 1,500 to 10,000, (b) an epoxy resin containing two or more epoxy groups in the molecule, and (c) an epoxy resin curing accelerator.

[0008] Japanese Patent Application Laid-Open No. 2005-125724

[0009] When the adhesive of Patent Document 1 is stored in the air, for example, the adhesive may absorb moisture from the air. However, when an FPC or an FPC-related product is manufactured using an adhesive containing moisture, the moisture in the adhesive rapidly vaporizes during a process of heating the FPC, such as a hot press process or a solder reflow process, which can cause the adhesive to easily peel off from an adherend adjacent to the adhesive.

[0010] To avoid such problems, conventional methods for manufacturing FPCs, etc., use a thoroughly dried adhesive to manufacture the FPCs, etc. However, since managing the moisture absorption state of the adhesive in this manner is cumbersome, there is a demand for an adhesive that is easier to use.

[0011] The present invention has been made in view of the above problems, and aims to provide an adhesive composition that can suppress peeling of an adherend after heating even when drying is insufficient, and a bonding film, a laminate with an adhesive layer, an electromagnetic wave shielding material, and a laminate that use this adhesive composition.

[0012] A first aspect of the present invention resides in adhesive compositions according to the following items [1] to [8].

[0013] [1] An adhesive composition comprising: a polyester resin (A) containing an ester bond connecting repeating units and one or two functional groups selected from the group consisting of a carboxy group and a carboxylic acid anhydride structure; an epoxy compound (B) in an amount of 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the polyester resin (A); and a cyclic carbodiimide (C) in an amount of 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the polyester resin (A).

[0014] [2] The adhesive composition according to [1], wherein the polyester resin (A) is a polyester polyamide and / or a polyester polyurethane. [3] The adhesive composition according to [1] or [2], wherein a cured product of the adhesive composition has a water absorption rate of 3% or less when immersed in water at 23°C for 24 hours. [4] The adhesive composition according to any one of [1] to [3], wherein the polyester resin (A) has an acid value of 0.1 mgKOH / g or more and 5 mgKOH / g or less. [5] The adhesive composition according to any one of [1] to [4], wherein the polyester resin (A) has a weight average molecular weight of 5,000 or more and 150,000 or less.

[0015] [6] The adhesive composition according to any one of [1] to [5], further comprising an inorganic filler (D). [7] The adhesive composition according to [6], wherein the content of the inorganic filler (D) is 10 parts by mass or more and 350 parts by mass or less per 100 parts by mass of the total content of the polyester resin (A), the epoxy compound (B), and the cyclic carbodiimide (C). [8] The adhesive composition according to [6] or [7], wherein the inorganic filler (D) is electrically conductive.

[0016] A second aspect of the present invention is a bonding film according to the following item [9]: [9] A bonding film having an adhesive layer and a release film provided on one or both sides of the adhesive layer and configured to be peelable from the adhesive layer, wherein the adhesive layer is composed of the adhesive composition according to any one of items [1] to [8] or a semi-cured product obtained by partially curing the adhesive composition.

[0017] A third aspect of the present invention resides in a laminate with an adhesive layer according to the following item

[10] :

[10] A laminate with an adhesive layer, comprising an adhesive layer and a base layer adhered to at least one surface of the adhesive layer, wherein the adhesive layer is composed of the adhesive composition according to any one of items [1] to [8] or a semi-cured product obtained by partially curing the adhesive composition.

[0018] A fourth aspect of the present invention resides in the electromagnetic shielding materials according to the following items

[11] to

[12] .

[11] An electromagnetic shielding material having a conductive adhesive layer, wherein the conductive adhesive layer is made of the adhesive composition according to item [8] or a semi-cured product obtained by partially curing the adhesive composition.

[12] The electromagnetic shielding material according to item

[11] , which has a protective layer provided on the conductive adhesive layer.

[0019] A fifth aspect of the present invention is a laminate according to the following item

[13] :

[13] A laminate comprising a cured product layer made of a cured product of the adhesive composition according to any one of items [1] to [8].

[0020] The adhesive composition contains a polyester resin (A), an epoxy compound (B), and a cyclic carbodiimide (C) in the above-mentioned specific ratio, and is capable of suppressing peeling of an adherend after heating even when the adhesive composition is not sufficiently dried.

[0021] Furthermore, the bonding film, the laminate with an adhesive layer, and the electromagnetic wave shielding material all have an adhesive layer made of the adhesive composition or a semi-cured product thereof. Therefore, by producing an FPC using these materials, peeling between the adhesive layer and a layer adjacent to the adhesive layer can be suppressed even when the FPC is heated in a hot press process, a solder reflow process, or the like.

[0022] Furthermore, the laminate has a cured product layer made of the cured product of the adhesive composition, and therefore, even when the laminate is heated during the manufacturing process of the laminate, peeling between the adhesive layer and the layer adjacent to the adhesive layer can be suppressed.

[0023] As described above, according to the above-described aspects, it is possible to provide an adhesive composition that can suppress peeling of an adherend after heating even when drying is insufficient, and a bonding film, a laminate with an adhesive layer, an electromagnetic wave shielding material, and a laminate that use this adhesive composition.

[0024] Fig. 1 is a partial cross-sectional view of a test piece A for evaluating flame retardancy in an example. Fig. 2 is a partial cross-sectional view of a bonding film B in an example. Fig. 3 is a partial cross-sectional view of a test piece C for evaluating adhesion in an example. Fig. 4 is a partial cross-sectional view of a test piece D for evaluating adhesion in an example.

[0025] (Adhesive composition) [Polyester-based resin (A)] The adhesive composition contains a polyester-based resin (A). The adhesive composition may contain one type of polyester-based resin (A), or may contain two or more types of polyester-based resins (A) having different structures.

[0026] In this specification, polyester-based resin (A) refers to a resin containing a polyester moiety in which multiple repeating units are bonded via ester bonds. That is, polyester-based resin (A) may be, for example, a polyester in which one or more types of repeating units are bonded via ester bonds. Furthermore, polyester-based resin (A) may be, for example, a resin containing an ester bond and a bonding group other than an ester bond as the bonding group connecting the repeating units. Examples of such resins include polyester polyamides containing ester bonds and amide bonds as bonding groups, and polyester polyurethanes containing ester bonds and urethane bonds as bonding groups. Furthermore, polyester-based resin (A) may have a linear molecular structure or a molecular structure containing a branched chain.

[0027] From the viewpoint of improving the solder heat resistance of the adhesive composition and more reliably obtaining the effect of suppressing peeling of the adherend after heating, the polyester-based resin (A) is preferably polyester polyamide and / or polyester polyurethane. Furthermore, polyester polyamide and polyester polyurethane have excellent filler dispersibility when a conductive inorganic filler (D) is used. Therefore, by using one or more resins selected from the group consisting of polyester polyamide and polyester polyurethane as the polyester-based resin (A), electrical conductivity can be more easily imparted to the adhesive composition and its cured product.

[0028] The polyester resin (A) contains one or two functional groups selected from the group consisting of a carboxy group and a carboxylic acid anhydride structure. The functional groups in the polyester resin (A) can react with other components, such as the epoxy compound (B) or the cyclic carbodiimide (C), to form covalent bonds. The functional groups may be located, for example, at the terminals of the molecular chains of the polyester resin (A) or on the side chains.

[0029] The water absorption rate of the polyester resin (A) when immersed in water at 23°C for 24 hours is preferably 3% or less. In this case, the adhesive composition and its cured product are less likely to absorb moisture, thereby further improving the long-term moist heat resistance of the adhesive composition and its cured product. The water absorption rate of the polyester resin (A) can be controlled, for example, by the ratio of hydrophobic repeating units to hydrophilic repeating units contained in the polyester resin (A). More specifically, when the polyester resin (A) is a polyester polyamide or polyester polyurethane, the water absorption rate can be reduced by increasing the ratio of relatively highly hydrophobic polyester moieties.

[0030] The glass transition temperature Tg of the polyester resin (A) is preferably 30° C. or higher and 150° C. or lower, more preferably 40° C. or higher and 140° C. or lower, even more preferably 50° C. or higher and 90° C. or lower, and particularly preferably 60° C. or higher and 70° C. or lower. In this case, the adhesive properties, electrical conductivity, and heat resistance of the adhesive composition can be further improved.

[0031] The acid value of the polyester resin (A) is preferably 0 mgKOH / g or more and 50 mgKOH / g or less, more preferably 0.1 mgKOH / g or more and 20 mgKOH / g or less, even more preferably 0.1 mgKOH / g or more and 5 mgKOH / g or less, and particularly preferably 0.5 mgKOH / g or more and 3 mgKOH / g or less. In this case, the content of carboxy groups and carboxylic anhydride structures in the polyester resin (A) can be appropriately increased. Therefore, a sufficient amount of cyclic carbodiimide (C) can be bonded to the polyester resin (A), thereby further improving solder heat resistance during moisture absorption. Note that the acid value of the resin in this specification is a value measured and calculated by potentiometric titration in accordance with JIS K 2501 (2003).

[0032] The weight average molecular weight of the polyester resin (A) is preferably 5,000 or more and 150,000 or less. In this case, the solder heat resistance of the adhesive composition is further improved, and peeling of the adherend when heated in an insufficiently dried state can be more effectively suppressed. From the same viewpoint, the number average molecular weight of the polyester resin (A) is preferably 1,500 or more and 100,000 or less. The number average molecular weight and weight average molecular weight values ​​of the polyester resin (A) are polystyrene-equivalent values ​​obtained by gel permeation chromatography (hereinafter also referred to as "GPC") using polystyrene as a standard substance.

[0033] Specific measurement conditions for GPC are, for example, as follows: Apparatus: "HLC-8320" manufactured by Tosoh Corporation Column: "TSKgel SuperMultiporeHZ-M" manufactured by Tosoh Corporation x 4 Solvent: Tetrahydrofuran Column temperature: 40°C Detector: RI Flow rate: 600 μL / min

[0034] From the viewpoints of adhesion, conductivity, and heat resistance, the content of the polyester resin (A) in the adhesive composition is preferably 5% by mass or more and 90% by mass or less, more preferably 10% by mass or more and 80% by mass or less, even more preferably 20% by mass or more and 75% by mass or less, and particularly preferably 30% by mass or more and 70% by mass or less, relative to the total solid content of the adhesive composition.

[0035] Polyesters Polyesters can also be used as the polyester-based resin (A). The adhesive composition may contain one type of polyester, or two or more types of polyesters.

[0036] The polyester has a repeating unit derived from a polycarboxylic acid having two or more carboxy groups, a repeating unit derived from a polyol having two or more hydroxy groups, and an ester bond connecting these. The polyester may have a linear molecular structure or a molecular structure including a branched chain. From the viewpoint of improving processability in heat press processing or heat lamination processing, the polyester preferably has a linear molecular structure. From the same viewpoint, the polyester preferably does not have an aromatic ring in its molecular structure.

[0037] The polyester preferably has a repeating unit derived from a dicarboxylic acid and a repeating unit derived from a diol, and may also have a repeating unit having a carboxy group and a functional group other than a carboxy group, such as a hydroxycarboxylic acid or a sulfocarboxylic acid.

[0038] Examples of dicarboxylic acids used in the polyester include chain aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and aromatic dicarboxylic acids. The polyester preferably contains a repeating unit derived from one or more dicarboxylic acids selected from the group consisting of chain aliphatic dicarboxylic acids having from 6 to 22 carbon atoms, aromatic dicarboxylic acids having from 6 to 22 carbon atoms, and alicyclic dicarboxylic acids having from 6 to 22 carbon atoms, and more preferably contains a repeating unit derived from a chain aliphatic dicarboxylic acid having from 6 to 22 carbon atoms and an alicyclic dicarboxylic acid having from 6 to 22 carbon atoms. In this case, the solder heat resistance and adhesiveness of the adhesive composition can be further improved.

[0039] Examples of the chain aliphatic dicarboxylic acid used in the polyester include succinic acid, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, dimer acid, etc. From the viewpoint of further improving solder heat resistance and adhesion, the polyester preferably contains repeating units derived from one or two chain aliphatic dicarboxylic acids selected from azelaic acid and dimer acid, and more preferably contains repeating units derived from azelaic acid.

[0040] Examples of the alicyclic dicarboxylic acid used in the polyester include 1,4-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, and anhydrides of 1,2-cyclohexanedicarboxylic acid.

[0041] Examples of aromatic dicarboxylic acids used in polyesters include aromatic dicarboxylic acids that do not have a sulfonic acid group or a sulfonate salt group, such as terephthalic acid, isophthalic acid, orthophthalic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, and 5-hydroxyisophthalic acid; aromatic sulfodicarboxylic acids such as sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, and 5-(4-sulfophenoxy)isophthalic acid; metal salts of aromatic sulfodicarboxylic acids; and ammonium salts of aromatic sulfodicarboxylic acids.

[0042] Examples of diols used in the polyester include chain aliphatic diols, alicyclic diols, aromatic diols, and ether bond-containing diols. From the viewpoint of solder heat resistance and adhesiveness, the polyester preferably contains a repeating unit derived from one or more diols selected from the group consisting of chain aliphatic diols having from 2 to 54 carbon atoms, aromatic diols having from 2 to 54 carbon atoms, and alicyclic diols having from 2 to 54 carbon atoms, and more preferably contains any one of a repeating unit derived from a chain aliphatic diol having from 2 to 54 carbon atoms, a repeating unit derived from an aromatic diol having from 2 to 54 carbon atoms, or a repeating unit derived from an alicyclic diol having from 2 to 54 carbon atoms.

[0043] Examples of the chain aliphatic diol include ethylene glycol, 1,2-propylene diol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, neopentyl glycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,9-nonanediol, 2-butyl-2-ethyl-1,3-propanediol, hydroxypivalic acid neopentyl glycol ester, dimethylol heptane, and 2,2,4-trimethyl-1,3-pentanediol.

[0044] Examples of alicyclic diols include 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, tricyclodecanediol, tricyclodecanedimethylol, spiroglycol, hydrogenated bisphenol A, ethylene oxide adducts of hydrogenated bisphenol A, and propylene oxide adducts of hydrogenated bisphenol A.

[0045] Examples of aromatic diols include benzenedimethanols such as 1,2-benzenedimethanol, 1,3-benzenedimethanol, and 1,4-benzenedimethanol; 2-(4-hydroxyphenyl)ethanol; bisphenols such as bisphenol A; ethylene oxide adducts of bisphenols; and propylene oxide adducts of bisphenols.

[0046] Examples of the ether bond-containing diol include diethylene glycol, triethylene glycol, dipropylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, neopentyl glycol ethylene oxide adduct, and neopentyl glycol propylene oxide adduct.

[0047] From the viewpoints of compatibility with the epoxy compound (B) and solution stability, the polyester preferably contains a repeating unit derived from a diol having a side chain. The side chain of the diol is preferably an alkyl group, more preferably an alkyl group having 1 to 5 carbon atoms. Examples of diols having a side chain include neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, and 2,2-dimethylolpropionic acid.

[0048] The polyester may also contain repeating units derived from aromatic hydroxycarboxylic acids such as 5-hydroxyisophthalic acid, p-hydroxybenzoic acid, p-hydroxyphenylpropionic acid, p-hydroxyphenylacetic acid, 6-hydroxy-2-naphthoic acid, and 4,4-bis(p-hydroxyphenyl)valeric acid.

[0049] The polyester may have a repeating unit derived from a polycarboxylic acid having three or more carboxy groups and / or a repeating unit derived from a polyol having three or more hydroxy groups. In this case, a branched chain can be introduced into the polyester. Furthermore, by introducing a branched chain into the polyester, the terminal group concentration (i.e., the number of reaction sites) of the resin can be increased. Therefore, for example, by reacting a polyester having a branched chain with a curing agent, a cured layer with a high crosslink density can be obtained.

[0050] The total content of repeating units derived from polycarboxylic acids having three or more carboxy groups and repeating units derived from polyols having three or more hydroxy groups is preferably 0.1 mol % or more and 5 mol % or less, and more preferably 0.1 mol % or more and 3 mol % or less, based on all repeating units in the polyester.

[0051] Examples of polycarboxylic acids having three or more carboxy groups include trimellitic acid, trimesic acid, ethylene glycol bis(anhydrotrimellitate), glycerol tris(anhydrotrimellitate), trimellitic anhydride, pyromellitic anhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA).

[0052] Examples of polyols having three or more hydroxy groups include glycerin, trimethylolethane, trimethylolpropane, and pentaerythritol.

[0053] From the viewpoint of improving solder heat resistance and adhesiveness, the polyester is preferably composed of a repeating unit derived from one or more dicarboxylic acids selected from the group consisting of a chain aliphatic dicarboxylic acid having from 6 to 22 carbon atoms, an aromatic dicarboxylic acid having from 6 to 22 carbon atoms, and an alicyclic dicarboxylic acid having from 6 to 22 carbon atoms, and a repeating unit of any one of a repeating unit derived from a chain aliphatic diol having from 2 to 54 carbon atoms, a repeating unit derived from an aromatic diol having from 2 to 54 carbon atoms, or a repeating unit derived from an alicyclic diol having from 2 to 54 carbon atoms.

[0054] The method for producing the polyester is not particularly limited, and known methods can be used. For example, the polycarboxylic acid, polyol, and other compounds used as needed may all be placed in a reaction vessel and then reacted, or raw materials such as the carboxylic acid may be placed in the reaction vessel in stages as the reaction progresses.

[0055] The polycondensation reaction of polycarboxylic acid and polyol may be carried out in the presence of a solvent, or may be carried out without using a solvent. Examples of the solvent include ester solvents such as ethyl acetate, butyl acetate, and ethyl butyrate; ether solvents such as dioxane, tetrahydrofuran, and diethyl ether; ketone solvents such as cyclohexanone, methyl ethyl ketone, and methyl isobutyl ketone; aromatic hydrocarbon solvents such as benzene, toluene, and xylene, and mixed solvents thereof. From the viewpoint of reducing environmental load, it is preferable to use ethyl acetate or methyl ethyl ketone as the solvent. As the reaction apparatus in which the polycondensation reaction is carried out, a reaction vessel equipped with a stirrer, or a mixing and kneading apparatus such as a kneader or a twin-screw extruder can be used.

[0056] In producing the polyester, a catalyst used to promote the esterification reaction, such as tetrabutoxy titanate, can be used as needed to promote the esterification reaction. In addition, in producing the polyester, a condensing agent or the like can also be used as needed.

[0057] When producing the polyester, a chain extender may be used as needed, such as the above-mentioned diols, compounds having one carboxy group and two hydroxy groups such as dimethylolpropionic acid and dimethylolbutanoic acid, and polyamines.

[0058] The chain extender is preferably a diol, more preferably a diol having a side chain, and even more preferably a diol having a branched chain. By using such a diol as a chain extender, electrical conductivity can be more easily imparted to the cured product of the adhesive composition. More specifically, the chain extender is preferably at least one compound selected from the group consisting of neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, and 2,2-dimethylolpropionic acid, and particularly preferably contains at least one compound selected from the group consisting of neopentyl glycol and 2-butyl-2-ethyl-1,3-propanediol and 2,2-dimethylolpropionic acid.

[0059] When producing a polyester, acid addition may be carried out as needed to introduce carboxy groups into the polyester. The amount of carboxy groups introduced by acid addition may be, for example, within a range of 0.1 mol% to 10 mol% relative to all repeating units contained in the polyester. If a monocarboxylic acid, dicarboxylic acid, or polyfunctional carboxylic acid compound is used when acid addition is carried out on a polyester, there is a risk of a decrease in molecular weight due to ester exchange. Therefore, when acid addition is carried out on a polyester, it is preferable to use an acid anhydride.

[0060] Examples of acid anhydrides include succinic anhydride, maleic anhydride, orthophthalic acid, 2,5-norbornene dicarboxylic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride, pyromellitic anhydride (PMDA), oxydiphthalic dianhydride (ODPA), 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA), 3,3',4,4'-diphenyltetracarboxylic dianhydride (BPDA), 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride (DSDA), 4,4'-(hexafluoroisopropylidene)diphthalic dianhydride (6FDA), and 2,2'-bis[(dicarboxyphenoxy)phenyl]propane dianhydride (BSAA).

[0061] The acid addition method is not particularly limited, and examples thereof include a method in which acid addition is performed in a bulk state after the completion of polyester polycondensation, and a method in which acid addition is performed after the polyester is dissolved. The acid addition performed in a bulk state has the advantage of a fast reaction rate. On the other hand, when acid addition is performed in a bulk state, gelation is more likely to occur if a large amount of acid is added. Furthermore, when acid addition is performed in a bulk state, the reaction temperature becomes high, making the polyester more susceptible to oxidation. Therefore, when acid addition is performed in a bulk state, care must be taken to prevent oxidation by blocking oxygen gas. When acid addition is performed in a solution state, the reaction is slow, but a large number of carboxy groups can be stably introduced into the polyester.

[0062] Polyester Polyamides Polyester polyamides can also be used as the polyester-based resin (A). The adhesive composition may contain one type of polyester polyamide, or two or more types of polyester polyamides.

[0063] The polyester polyamide has a polyester portion formed by bonding multiple repeating units via ester bonds and an amide portion formed by bonding multiple repeating units via amide bonds. The polyester portion may have two or more ester bonds. The polyamide portion may have two or more amide bonds. The polyester portion and the polyamide portion may be bonded via an ester bond or via an amide bond.

[0064] The polyester polyamide is preferably a resin having a polyester chain and two or more amide bonds, a resin having a polyamide chain and two or more ester bonds, or a resin having a polyester chain and a polyamide chain. The weight-average molecular weight of the polyester chain may be 1,000 or more. The weight-average molecular weight of the polyamide chain may be 1,000 or more. The upper limit of the weight-average molecular weight of each of the polyester chain and the polyamide chain is not particularly limited, but may be, for example, 150,000 or less.

[0065] The polyester polyamide may have a linear molecular structure or a molecular structure containing a branched chain. From the viewpoint of improving processability in hot press processing or hot lamination processing, the polyester polyamide preferably has a linear molecular structure. From the same viewpoint, the polyester polyamide preferably does not have an aromatic ring in its molecular structure.

[0066] The polyester polyamide has repeating units derived from a polycarboxylic acid having two or more carboxy groups, repeating units derived from a polyol having two or more hydroxy groups, and repeating units derived from a polyamine having two or more amino groups. The polyester polyamide preferably has repeating units derived from a dicarboxylic acid, repeating units derived from a diol, and repeating units derived from a diamine.

[0067] More specifically, the polyester portion of the polyester polyamide has a repeating unit derived from a polycarboxylic acid and a repeating unit derived from a polyol. Examples of the polycarboxylic acid used in the polyester portion include the same dicarboxylic acids as those used in the polyesters described above, polycarboxylic acids having three or more carboxy groups, hydroxycarboxylic acids, and sulfocarboxylic acids. From the viewpoint of further improving the solder heat resistance and adhesiveness of the adhesive composition, the polyester portion of the polyester polyamide preferably contains a repeating unit derived from one or more dicarboxylic acids selected from the group consisting of a chain aliphatic dicarboxylic acid having 6 to 22 carbon atoms, an aromatic dicarboxylic acid having 6 to 22 carbon atoms, and an alicyclic dicarboxylic acid having 6 to 22 carbon atoms, and more preferably contains a repeating unit derived from a chain aliphatic dicarboxylic acid having 6 to 22 carbon atoms and an alicyclic dicarboxylic acid having 6 to 22 carbon atoms.

[0068] Examples of alcohols used in the polyester portion include diols similar to the polyols used in the polyesters described above, and polyols having three or more hydroxy groups. From the viewpoints of solder heat resistance and adhesiveness, the polyester portion in the polyester polyamide preferably contains a repeating unit derived from one or more diols selected from the group consisting of a chain aliphatic diol having from 2 to 54 carbon atoms, an aromatic diol having from 2 to 54 carbon atoms, and an alicyclic diol having from 2 to 54 carbon atoms, and more preferably contains any one of a repeating unit derived from a chain aliphatic diol having from 2 to 54 carbon atoms, a repeating unit derived from an aromatic diol having from 2 to 54 carbon atoms, or a repeating unit derived from an alicyclic diol having from 2 to 54 carbon atoms.

[0069] The polyester portion of the polyester polyamide may have repeating units derived from a polycarboxylic acid having three or more carboxy groups and / or repeating units derived from a polyol having three or more hydroxy groups. In this case, a branched chain can be introduced into the polyester portion. Furthermore, by introducing a branched chain into the polyester portion, the terminal group concentration (i.e., the number of reaction sites) of the resin can be increased. Therefore, for example, by reacting a polyester polyamide having a branched chain introduced therein with a curing agent, a cured layer with a high crosslink density can be obtained.

[0070] The total content of repeating units derived from polycarboxylic acids having three or more carboxy groups and repeating units derived from polyols having three or more hydroxy groups is preferably 0.1 mol % or more and 5 mol % or less, and more preferably 0.1 mol % or more and 3 mol % or less, based on all repeating units in the polyester moiety.

[0071] More specifically, the polyamide portion of the polyester polyamide has a repeating unit derived from a polycarboxylic acid and a repeating unit derived from a polyamine. The polyamide portion of the polyester polyamide preferably has a repeating unit derived from a dicarboxylic acid and a repeating unit derived from a diamine. The polyamide portion may also have a repeating unit having a carboxy group and a functional group other than a carboxy group, such as a hydroxycarboxylic acid or a sulfocarboxylic acid.

[0072] Examples of the carboxylic acid used in the polyamide portion include the same dicarboxylic acid as the carboxylic acid used in the polyester portion, polycarboxylic acids having three or more carboxy groups, hydroxycarboxylic acids, sulfocarboxylic acids, etc. From the viewpoint of further improving solder heat resistance and adhesiveness, it is preferable that the polyamide portion contains a repeating unit derived from one or more dicarboxylic acids selected from the group consisting of chain aliphatic dicarboxylic acids having 6 to 22 carbon atoms (excluding dimerized aliphatic diacids), aromatic dicarboxylic acids having 6 to 22 carbon atoms, alicyclic dicarboxylic acids having 6 to 22 carbon atoms (excluding dimerized aliphatic diacids), and dimerized aliphatic diacids having 20 to 48 carbon atoms. More specifically, the polyamide portion may contain repeating units derived from one or more dicarboxylic acids selected from the group consisting of the chain aliphatic dicarboxylic acids, the aromatic dicarboxylic acids, and the alicyclic dicarboxylic acids, and repeating units derived from the dimerized aliphatic diacids, or may contain repeating units derived from one or more dicarboxylic acids selected from the group consisting of the chain aliphatic dicarboxylic acids, the aromatic dicarboxylic acids, and the alicyclic dicarboxylic acids, and may contain repeating units derived from the dimerized aliphatic diacids.

[0073] From the viewpoint of further improving solder heat resistance and adhesiveness, the polyamide portion preferably contains a repeating unit derived from one or more dicarboxylic acids selected from the group consisting of the chain aliphatic dicarboxylic acids, the alicyclic dicarboxylic acids, and the dimerized aliphatic diacids, and more preferably contains a repeating unit derived from azelaic acid. Furthermore, the number of carbon atoms in the chain aliphatic dicarboxylic acids, aromatic dicarboxylic acids, and alicyclic dicarboxylic acids contained in the polyamide portion is preferably 6 to 12, more preferably 8 to 10. The number of carbon atoms in the dimerized aliphatic diacid contained in the polyamide portion is preferably 30 to 48, more preferably 32 to 40.

[0074] Examples of polyamines used in the polyamide portion of the polyester polyamide include diamines and aminocarboxylic acids.

[0075] Diamines used in the polyamide portion include diaminocyclohexane, piperidine, isophoronediamine, 1,2-diaminoethane, 1,3-diaminopropane, 1,4-diaminobutane, 1,5-diaminopentane, 1,6-diaminohexane, 1,7-diaminoheptane, 1,8-diaminooctane, 1,9-diaminononane, o-(or m-, p-)phenylenediamine, o-(or m-, p-)xylenediamine, 3,3'-(or 3,4'-)diaminodiphenyl diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 3,3'-(or 3,4'-)diaminodiphenylmethane, 4,4'-diaminodiphenylmethane, 3,3'-(or 3,4'-, 4,4'-)diaminodiphenyldifluoromethane, 3,3'-(or 3,4'-, 4,4'-)diaminodiphenyl sulfone, 3,3'-(or 3,4'-, 4,4'-)diaminodiphenyl sulfide, 3,3'-(or 3,4'-, 4,4'-)diaminodiphenyl ketone, 2,2-bis(2,2-biphenyl) bis(3-aminophenyl)propane, 2,2'-(3,4'-diaminodiphenyl)propane, 2,2-bis(4-aminophenyl)propane, 2,2-bis(3-aminophenyl)hexafluoropropane, 2,2-(3,4'-diaminodiphenyl)hexafluoropropane, 2,2-bis(4-aminophenyl)hexafluoropropane, 1,3-(or 1,4-)bis(3-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, 3,3'- (1-phenylenebis(1-methylethylidene))bisaniline, 3,4'-(1,4-phenylenebis(1-methylethylidene))bisaniline, 4,4'-(1,4-phenylenebis(1-methylethylidene))bisaniline, 2,2-bis(4-(3-aminophenoxy)phenyl)propane, 2,2-bis(4-(4-aminophenoxy)phenyl)propane, and 2,2-bis(4-(4-aminophenoxy)phenyl)hexafluoropropane.

[0076] From the viewpoint of soldering heat resistance, the polyamide portion preferably contains one or more repeating units selected from the group consisting of aromatic diamines having from 6 to 44 carbon atoms and diamines having an alicyclic skeleton having from 6 to 44 carbon atoms, more preferably contains a repeating unit derived from a diamine having an alicyclic skeleton having from 6 to 44 carbon atoms, and particularly preferably contains isophoronediamine. The diamine preferably has from 8 to 30 carbon atoms, more preferably from 10 to 24 carbon atoms.

[0077] From the viewpoints of solder heat resistance, adhesion, and conductivity, the polyamide portion of the polyester polyamide preferably contains repeating units derived from one or more dicarboxylic acids selected from the group consisting of chain aliphatic dicarboxylic acids having 6 to 22 carbon atoms (excluding dimeric aliphatic diacids), aromatic dicarboxylic acids having 6 to 22 carbon atoms, alicyclic dicarboxylic acids having 6 to 22 carbon atoms (excluding dimeric aliphatic diacids), and dimeric aliphatic diacids having 20 to 48 carbon atoms, and repeating units derived from one or more diamines selected from the group consisting of aromatic diamines having 6 to 44 carbon atoms and diamines having an alicyclic skeleton having 6 to 44 carbon atoms. More preferably, the polyamide portion contains repeating units derived from one or more dicarboxylic acids selected from the group consisting of chain aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, and dimeric aliphatic diacids, and repeating units derived from the diamines having an alicyclic skeleton.

[0078] The polyester polyamide also includes a polyester portion including a repeating unit derived from one or more dicarboxylic acids selected from the group consisting of a chain aliphatic dicarboxylic acid having from 6 to 22 carbon atoms, an aromatic dicarboxylic acid having from 6 to 22 carbon atoms, and an alicyclic dicarboxylic acid having from 6 to 22 carbon atoms, and a polyester portion including a repeating unit derived from one or more diols selected from the group consisting of a chain aliphatic diol having from 2 to 54 carbon atoms, an aromatic diol having from 2 to 54 carbon atoms, and an alicyclic diol having from 2 to 54 carbon atoms; It is preferable that the polyester polyamide comprises a polyamide moiety containing repeating units derived from one or more dicarboxylic acids selected from the group consisting of chain aliphatic dicarboxylic acids having from 6 to 22 carbon atoms (excluding dimeric aliphatic diacids), aromatic dicarboxylic acids having from 6 to 22 carbon atoms, alicyclic dicarboxylic acids having from 6 to 22 carbon atoms (excluding dimeric aliphatic diacids), and dimeric aliphatic diacids having from 20 to 48 carbon atoms, and repeating units derived from one or more diamines selected from the group consisting of aromatic diamines having from 6 to 44 carbon atoms and diamines having an alicyclic skeleton having from 6 to 44 carbon atoms. Such polyester polyamides containing polyester moieties and polyamide moieties can easily produce adhesive compositions that have low water absorption and excellent long-term moist heat resistance.

[0079] From the viewpoints of adhesiveness, electrical conductivity, and heat resistance, the glass transition temperature of the polyester portion in the polyester polyamide is preferably 40°C or higher and 150°C or lower, more preferably 45°C or higher and 120°C or lower, even more preferably 50°C or higher and 90°C or lower, and particularly preferably 60°C or higher and 70°C or lower.

[0080] From the viewpoints of adhesiveness, electrical conductivity, and heat resistance, the glass transition temperature of the polyester polyamide is preferably 30°C or higher and 150°C or lower, more preferably 40°C or higher and 140°C or lower, even more preferably 50°C or higher and 90°C or lower, and particularly preferably 60°C or higher and 70°C or lower.

[0081] From the viewpoints of solder heat resistance, electrical conductivity, and heat resistance, the weight-average molecular weight of the polyester polyamide is preferably 5,000 to 150,000, more preferably 10,000 to 100,000, even more preferably 30,000 to 80,000, and particularly preferably 40,000 to 60,000. From the same viewpoints, the number-average molecular weight of the polyester polyamide is preferably 1,500 to 50,000, more preferably 10,000 to 25,000, and even more preferably 13,000 to 20,000.

[0082] From the viewpoints of solder heat resistance, adhesiveness, and conductivity, the amine value of the polyester polyamide is preferably 1.0 mgKOH / g or more and 12.0 mgKOH / g or less, more preferably 3.0 mgKOH / g or more and 11.0 mgKOH / g or less, even more preferably 6.0 mgKOH / g or more and 10.0 mgKOH / g or less, and particularly preferably 7.0 mgKOH / g or more and 8.0 mgKOH / g or less. The amine value of the resin in this specification is a value measured and calculated by potentiometry in accordance with JIS K 7237 (1995).

[0083] The method for producing polyester polyamide is not particularly limited, and known methods can be used. For example, the above-mentioned polycarboxylic acid, polyol, polyamine, and other compounds used as needed may all be placed in a reaction vessel and then reacted, or raw materials such as polycarboxylic acid may be added to the reaction vessel stepwise as the reaction progresses. In the polycondensation of polyester polyamide, the amounts of polycarboxylic acid, polyol, and polyamine added should be set so that the ratio of the total amount of carboxyl groups to the sum of the total amount of hydroxyl groups and the total amount of amino groups is preferably 0.9 to 1.1, more preferably 0.98 to 1.02, and particularly preferably 1.

[0084] The polycondensation reaction may be carried out in the presence of a solvent or without using a solvent. As the solvent, the same solvent as that used in the above-mentioned polyester polycondensation reaction can be used. From the viewpoint of reducing the environmental load, it is preferable to use ethyl acetate or methyl ethyl ketone as the solvent. As a reaction apparatus for carrying out the polycondensation reaction, a reaction vessel equipped with a stirring device, or a mixing and kneading apparatus such as a kneader or a twin-screw extruder can be used.

[0085] When producing polyester polyamide, a catalyst used for promoting esterification reaction and / or amidation reaction, such as tetrabutoxy titanate, can be used as needed to promote the esterification reaction or amidation reaction. Furthermore, when producing polyester polyamide, a condensing agent, a chain extender, etc. can also be used as needed. The chain extenders used in the production of polyester polyamide and their preferred embodiments are the same as those used in the production of polyester.

[0086] When producing polyester polyamide, acid addition may be performed as needed to introduce carboxy groups into the polyester polyamide. The amount of carboxy groups introduced by acid addition may be, for example, within a range of 0.1 mol% to 10 mol% based on the total of the repeating units derived from polycarboxylic acid and the repeating units derived from polyol contained in the polyester polyamide. If a monocarboxylic acid, dicarboxylic acid, or polyfunctional carboxylic acid compound is used in acid addition to polyester polyamide, a decrease in molecular weight may occur due to transesterification. Therefore, when acid addition is performed on polyester polyamide, it is preferable to use an acid anhydride. Examples of acid anhydrides used in acid addition to polyester polyamide include the same acid anhydrides as those used in acid addition to polyesters.

[0087] Polyester Polyurethane The polyester resin (A) may be a polyester polyurethane. The adhesive composition may contain one type of polyester polyurethane, or two or more types of polyester polyurethane.

[0088] The polyester polyurethane has a polyester portion formed by bonding multiple repeating units via ester bonds and a polyurethane portion formed by bonding multiple repeating units via urethane bonds. The polyester portion may have two or more ester bonds. The polyurethane portion may have two or more urethane bonds. The polyester portion and the polyurethane portion may be bonded via an ester bond or a urethane bond.

[0089] The polyester polyurethane has, for example, a repeating unit derived from a polycarboxylic acid, a repeating unit derived from a polyol, and a repeating unit derived from a polyisocyanate. The polyester polyurethane preferably has a repeating unit derived from a dicarboxylic acid, a repeating unit derived from a diol, and a repeating unit derived from a diisocyanate.

[0090] Furthermore, the polyester polyurethane may contain repeating units derived from a polyester polyol, repeating units derived from a polyisocyanate, and a structure derived from a chain extender, or may contain repeating units derived from a polyester polyol, repeating units derived from a polyisocyanate, and a structure derived from a diol as a chain extender.

[0091] More specifically, the polyester portion of the polyester polyurethane has a repeating unit derived from a polycarboxylic acid and a repeating unit derived from a polyol. The number average molecular weight of the polyester portion of the polyester polyurethane is preferably 1,000 to 50,000, more preferably 2,000 to 40,000, even more preferably 3,000 to 30,000, particularly preferably 8,000 to 30,000, and most preferably 15,000 to 30,000. In this case, the adhesive properties and heat resistance of the adhesive composition can be more easily improved, and electrical conductivity can be more easily imparted to the cured product of the adhesive composition.

[0092] Examples of the polycarboxylic acid used in the polyester portion include the same dicarboxylic acids as those used in the polyesters described above, polycarboxylic acids having three or more carboxy groups, hydroxycarboxylic acids, and sulfocarboxylic acids.

[0093] The polyester portion of the polyester polyurethane preferably contains 30 mol% or more of repeating units derived from an aromatic carboxylic acid, more preferably 45 mol% or more of repeating units derived from an aromatic carboxylic acid, and even more preferably 60 mol% or more of repeating units derived from an aromatic carboxylic acid, relative to the total amount of repeating units derived from a polycarboxylic acid contained in the polyester portion. In this case, the adhesive composition can have further improved adhesion, heat resistance, and moist heat resistance. Examples of aromatic carboxylic acids include aromatic polycarboxylic acids, aromatic sulfocarboxylic acids, and aromatic oxycarboxylic acids. From the perspective of further improving the adhesive properties of the adhesive composition, the polyester portion preferably contains repeating units derived from one or two aromatic carboxylic acids selected from terephthalic acid and isophthalic acid. From the same perspective, it is more preferable that the aromatic carboxylic acid contained in the polyester portion is terephthalic acid and / or isophthalic acid.

[0094] Furthermore, examples of polyols used in the polyester portion include diols similar to those used in the polyesters described above, and polyols having three or more hydroxy groups. From the viewpoints of compatibility with the epoxy compound (B) and solution stability, the polyester portion preferably contains a repeating unit derived from a diol having a side chain. The side chain of the diol is preferably an alkyl group, more preferably an alkyl group having 1 to 5 carbon atoms. Examples of diols having a side chain include neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, and 2,2-dimethylolpropionic acid.

[0095] Furthermore, it is preferable that the polyester portion contains a repeating unit derived from a diol. In this case, electrical conductivity can be more easily imparted to a cured product of the adhesive composition, and the electrical conductivity of the cured product can be easily maintained even after soldering, long-term reliability testing, and thermal cycling testing. From the viewpoint of more reliably achieving this effect, it is preferable that the polyester portion contains a repeating unit derived from a diol having a hydrocarbon group containing 5 to 32 carbon atoms, more preferably a repeating unit derived from a diol having a hydrocarbon group containing 5 to 16 carbon atoms, and particularly preferably a repeating unit derived from a diol having a hydrocarbon group containing 7 to 12 carbon atoms.

[0096] From the same viewpoint, the repeating unit derived from the diol in the polyester portion preferably has a hydrocarbon group having from 5 to 32 carbon atoms and also has an alicyclic structure or two or more side chains, more preferably two or more side chains, and particularly preferably two side chains. The repeating unit derived from the diol described above may be contained in the polyester portion or, as will be described later, in the polyurethane portion, but from the viewpoint of more reliably obtaining the effects described above, it is preferable that the repeating unit derived from the diol described above be contained in the polyurethane portion.

[0097] The polyester portion of the polyester polyurethane may have a repeating unit derived from a polycarboxylic acid having three or more carboxy groups and / or a repeating unit derived from a polyol having three or more hydroxy groups. In this case, a branched chain can be introduced into the polyester portion. Furthermore, by introducing a branched chain into the polyester portion, the terminal group concentration (i.e., the number of reaction sites) of the resin can be increased. Therefore, for example, by reacting a polyester polyurethane having a branched chain introduced therein with a curing agent, a cured layer with a high crosslink density can be obtained.

[0098] The total content of repeating units derived from polycarboxylic acids having three or more carboxy groups and repeating units derived from polyols having three or more hydroxy groups is preferably 0.1 mol % or more and 5 mol % or less, and more preferably 0.1 mol % or more and 3 mol % or less, based on all repeating units in the polyester moiety.

[0099] The polyurethane portion of the polyester polyurethane preferably contains a repeating unit derived from a diisocyanate, and more preferably contains a repeating unit derived from a diisocyanate having a hydrocarbon group having from 8 to 14 carbon atoms. A methylene group in the hydrocarbon group of the diisocyanate may be replaced with a non-reactive bond such as -O-, -S-, -CO-, -COO-, or -OCO-.

[0100] From the viewpoint of more easily imparting electrical conductivity to a cured product of the adhesive composition and easily maintaining the electrical conductivity of the cured product even after soldering, long-term reliability testing, and thermal cycle testing, the number of carbon atoms in the hydrocarbon group in the diisocyanate is more preferably 8 to 12, and even more preferably 8 to 10. From the same viewpoint, it is preferable that the diisocyanate has an alicyclic structure.

[0101] The content of the repeating units derived from the diisocyanate in the polyurethane portion is preferably 70 mol% or more, more preferably 90 mol% or more, and even more preferably 100 mol% of the content of all repeating units derived from diisocyanates contained in the polyester polyurethane.

[0102] From the viewpoint of further improving the adhesive properties of the adhesive composition, the content of repeating units derived from diisocyanate in the polyester polyurethane is preferably 5 to 50 molar equivalents per 1 molar equivalent of the polyester moiety. In other words, the polyester polyurethane preferably has urethane bonds derived from diisocyanate in an amount of 10 to 100 molar equivalents per 1 molar equivalent of the polyester moiety.

[0103] The polyurethane portion of the polyester polyurethane may contain repeating units derived from a polyisocyanate having three or more isocyanates in addition to repeating units derived from a diisocyanate.

[0104] Examples of polyisocyanates used in the polyurethane portion include diisocyanates, diisocyanate dimers (i.e., uretdiones), and diisocyanate trimers such as isocyanurates, diisocyanate triol adducts, and biuret. The polyurethane portion may contain repeating units derived from one type of polyisocyanate among these polyisocyanates, or may contain repeating units derived from two or more types of polyisocyanates.

[0105] More specifically, examples of diisocyanates include diphenylmethane diisocyanate, 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 1,5-naphthalene diisocyanate, 2,6-naphthalene diisocyanate, 4,4'-diisocyanate diphenyl ether, m-xylylene diisocyanate, 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, methylenebis(4-cyclohexyl diisocyanate), isophorone diisocyanate, norbornane diisocyanate, and norbornene diisocyanate.

[0106] The polyurethane portion preferably contains repeating units derived from one or more isocyanates selected from the group consisting of chain aliphatic diisocyanates and alicyclic diisocyanates, and more preferably contains repeating units derived from alicyclic diisocyanates. In this case, the cured product of the adhesive composition can be made transparent. Furthermore, in this case, electrical conductivity can be more easily imparted to the cured product of the adhesive composition, and the electrical conductivity of the cured product can be easily maintained even after soldering, long-term reliability testing, and thermal cycling testing.

[0107] Furthermore, from the viewpoints of availability and conductivity after a thermal cycle test, it is more preferable that the polyurethane portion contains repeating units derived from one or more isocyanates selected from the group consisting of 1,3-bis(isocyanatomethyl)cyclohexane, 1,4-bis(isocyanatomethyl)cyclohexane, methylenebis(4-cyclohexyldiisocyanate), and norbornane diisocyanate, and it is particularly preferable that the polyurethane portion contains repeating units derived from 1,3-bis(isocyanatomethyl)cyclohexane.

[0108] The polyurethane portion may contain a repeating unit derived from a polyol. Examples of polyols used in the polyurethane portion include diols similar to the alcohols used in the polyesters described above and polyols having three or more hydroxy groups. The polyurethane portion preferably contains a repeating unit derived from a diol having a side chain. The side chain of the diol is preferably an alkyl group, more preferably an alkyl group having 1 to 5 carbon atoms.

[0109] Furthermore, it is preferable that the polyurethane portion contains a repeating unit derived from a diol. In this case, electrical conductivity can be more easily imparted to a cured product of the adhesive composition, and the electrical conductivity of the cured product can be easily maintained even after soldering, long-term reliability testing, and thermal cycling testing. From the viewpoint of more reliably achieving this effect, it is preferable that the polyurethane portion contains a repeating unit derived from a diol having a hydrocarbon group containing 5 to 32 carbon atoms, more preferably a repeating unit derived from a diol having a hydrocarbon group containing 5 to 16 carbon atoms, and particularly preferably a repeating unit derived from a diol having a hydrocarbon group containing 7 to 12 carbon atoms.

[0110] From the same viewpoint, the repeating unit derived from a diol in the polyurethane portion preferably has a hydrocarbon group having from 5 to 32 carbon atoms and also has an alicyclic structure or two or more side chains, more preferably has two or more side chains, and particularly preferably has two side chains.

[0111] Examples of chain extenders used in polyester polyurethanes include diols similar to those used in the polyester portion, and compounds having one carboxy group and two hydroxy groups, such as dimethylolpropionic acid and dimethylolbutanoic acid.

[0112] From the viewpoint of more easily imparting electrical conductivity to a cured product of the adhesive composition, the chain extender is preferably a diol. Furthermore, from the viewpoint of further improving compatibility with the epoxy compound (B) and solution stability in addition to the above effect, the chain extender is more preferably a diol having a side chain, and particularly preferably a diol having a branched chain. Furthermore, the side chain of the diol is preferably an alkyl group, more preferably an alkyl group having 1 to 5 carbon atoms. More specifically, the chain extender preferably contains at least one compound selected from the group consisting of neopentyl glycol, 2-butyl-2-ethyl-1,3-propanediol, and 2,2-dimethylolpropionic acid, and particularly preferably contains at least one compound selected from the group consisting of neopentyl glycol and 2-butyl-2-ethyl-1,3-propanediol and 2,2-dimethylolpropionic acid.

[0113] Polyamines can also be used as chain extenders. In this case, urea bonds are formed in the polyester polyurethane, but in some cases, it may be preferable for the polyester polyurethane to contain no urea bonds.

[0114] From the viewpoints of adhesiveness, conductivity, and heat resistance, the glass transition temperature of the polyester portion of the polyester polyurethane is preferably 40°C or higher and 150°C or lower, more preferably 45°C or higher and 120°C or lower, even more preferably 50°C or higher and 90°C or lower, and particularly preferably 60°C or higher and 70°C or lower.

[0115] Furthermore, from the viewpoints of adhesiveness, conductivity, and heat resistance, the glass transition temperature of the polyester polyurethane is preferably 30°C or higher and 150°C or lower, more preferably 40°C or higher and 140°C or lower, even more preferably 50°C or higher and 90°C or lower, and particularly preferably 60°C or higher and 70°C or lower.

[0116] From the viewpoint of electrical conductivity and heat resistance, the number average molecular weight of the polyester polyurethane is preferably 5,000 or more and 100,000 or less, more preferably 10,000 or more and 80,000 or less, even more preferably 20,000 or more and 60,000 or less, and particularly preferably 25,000 or more and 50,000 or less.

[0117] From the viewpoint of electrical conductivity and heat resistance, the molecular weight per urethane bond in the polyester polyurethane is preferably 200 to 8,000, more preferably 200 to 5,000, even more preferably 300 to 2,000, particularly preferably 400 to 1,500, and most preferably 700 to 1,000. The molecular weight per urethane bond can be obtained by dividing the number average molecular weight of the polyester polyurethane by the number of urethane bonds per molecule. The number of urethane bonds per molecule can also be calculated, for example, based on the amounts of raw materials used in the synthesis of the polyester polyurethane. More specifically, when polyester polyol and isocyanate are used to synthesize the polyester polyurethane, the number of moles of isocyanate groups reacted with one mole of polyester polyol can be considered to be the "number of urethane bonds per molecule."

[0118] The method for producing polyester polyurethane is not particularly limited, and known methods can be used. For example, the above-mentioned polyester polyol, polyisocyanate, and other compounds used as needed may all be placed in a reaction vessel and then reacted, or raw materials such as polyester polyol may be placed in the reaction vessel in stages as the reaction progresses. In the polycondensation of polyester polyurethane, the amounts of raw materials added may be set so that the ratio of the total amount of isocyanate groups to the total amount of hydroxy groups is preferably 0.9 to 1.1, more preferably 0.98 to 1.02, and particularly preferably 1.

[0119] The polycondensation reaction may be carried out in the presence of a solvent inert to isocyanate groups, or may be carried out without using a solvent. The solvent may be the same as that used in the polyester polycondensation reaction described above. From the viewpoint of reducing environmental impact, it is preferable to use ethyl acetate or methyl ethyl ketone as the solvent. The reaction apparatus used to carry out the polycondensation reaction may be a reaction vessel equipped with a stirrer, or a mixing / kneading apparatus such as a kneader or a twin-screw extruder.

[0120] In producing polyester polyurethane, a catalyst for accelerating the urethanization reaction can be used as needed to accelerate the urethanization reaction. Examples of this type of catalyst include tin-based catalysts such as trimethyltin laurate, dimethyltin dilaurate, trimethyltin hydroxide, dimethyltin dihydroxide, and stannous octoate; lead-based catalysts such as red oleate and red 2-ethylhexoate; and amine-based catalysts such as triethylamine, tributylamine, morpholine, diazabicyclooctane, and diazabicycloundecene.

[0121] When producing polyester polyurethane, acid addition may be performed as needed to introduce carboxy groups into the polyester polyurethane. The amount of carboxy groups introduced by acid addition may be, for example, within a range of 0.1 mol% to 10 mol% relative to the repeating units derived from carboxylic acid and repeating units derived from alcohol contained in the polyester polyurethane. If a monocarboxylic acid, dicarboxylic acid, or polyfunctional carboxylic acid compound is used in acid addition to polyester polyurethane, there is a risk of a decrease in molecular weight due to transesterification. Therefore, when acid addition is performed on polyester polyurethane, it is preferable to use an acid anhydride. Examples of acid anhydrides used in acid addition to polyester polyurethane include the same acid anhydrides as those used in acid addition to polyesters.

[0122] [Epoxy Compound (B)] The adhesive composition contains an epoxy compound (B). In this specification, the epoxy compound (B) refers to a compound having one or more epoxy groups in its molecular structure. The epoxy compound (B) imparts adhesive properties to the adhesive composition and has the effect of improving the heat resistance, etc., of a cured product of the adhesive composition. The epoxy compound (B) may be a low molecular weight compound having an epoxy group, or may be an oligomer or polymer having an epoxy group. The adhesive composition may contain one type of epoxy compound (B), or may contain two or more types of epoxy compounds (B) having different structures. It is preferable that the epoxy compound (B) has two or more epoxy groups per molecule.

[0123] The content of the epoxy compound (B) in the adhesive composition is 1 part by mass or more and 50 parts by mass or less per 100 parts by mass of the polyester resin (A). By making the content of the epoxy compound (B) 1 part by mass or more, preferably 5 parts by mass or more, and more preferably 10 parts by mass or more per 100 parts by mass of the polyester resin (A), the adhesive properties of the adhesive composition can be increased and the heat resistance of the cured product can be improved. If the content of the epoxy compound (B) is less than 1 part by mass per 100 parts by mass of the polyester resin (A), the adhesive properties of the adhesive composition and the heat resistance of the cured product may be reduced.

[0124] On the other hand, if the content of the epoxy compound (B) is excessively high, the epoxy compound (B) may easily react with other functional groups in the adhesive composition, which may result in a decrease in storage stability. Such a problem can be easily avoided by setting the content of the epoxy compound (B) to 50 parts by mass or less, preferably 40 parts by mass or less, and more preferably 30 parts by mass or less, per 100 parts by mass of the polyester resin (A).

[0125] When constituting a preferred range of the content of the epoxy compound (B), the above-mentioned upper and lower limits of the content of the epoxy compound (B) can be combined arbitrarily. For example, the preferred range of the content of the epoxy compound (B) may be 5 parts by mass or more and 40 parts by mass or less, or 10 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of the polyester-based resin (A).

[0126] Examples of the epoxy compound (B) include glycidyl esters, glycidyl ethers, and epoxy resins. Examples of the glycidyl esters include orthophthalic acid diglycidyl ester, isophthalic acid diglycidyl ester, terephthalic acid diglycidyl ester, p-hydroxybenzoic acid diglycidyl ester, tetrahydrophthalic acid diglycidyl ester, succinic acid diglycidyl ester, adipic acid diglycidyl ester, sebacic acid diglycidyl ester, and trimellitic acid triglycidyl ester.

[0127] Examples of glycidyl ethers include diglycidyl ether of bisphenol A and oligomers thereof, ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetraphenyl glycidyl ether ethane, triphenyl glycidyl ether ethane, polyglycidyl ether of sorbitol, and polyglycidyl ether of polyglycerol.

[0128] Examples of epoxy resins include novolac type epoxy resins such as phenol novolac epoxy resin, o-cresol novolac epoxy resin, and bisphenol A novolac epoxy resin; brominated bisphenol A type epoxy resin; phosphorus-containing epoxy resin; trisphenolmethane skeleton-containing epoxy resin; dicyclopentadiene skeleton-containing epoxy resin; naphthalene skeleton-containing epoxy resin; anthracene type epoxy resin; tertiary butylcatechol type epoxy resin; biphenyl type epoxy resin; and bisphenol S type epoxy resin.

[0129] From the viewpoint of adhesiveness and solder heat resistance, the adhesive composition preferably contains an epoxy resin containing a trisphenolmethane skeleton as the epoxy compound (B).

[0130] From the viewpoint of further improving the heat resistance of the cured product of the adhesive composition, it is preferable that the epoxy compound (B) contains a compound having three or more epoxy groups in one molecule. Use of such a compound increases the crosslinking reactivity with the polyester polyurethane, thereby further improving the heat resistance of the cured product.

[0131] From the viewpoint of further enhancing the effect of improving heat resistance, the content of the compound having three or more epoxy groups in one molecule is preferably 15% by mass or more, more preferably 20% by mass or more, and particularly preferably 25% by mass or more, based on the total mass of the epoxy compound (B).

[0132] [Cyclic Carbodiimide (C)] The adhesive composition contains a cyclic carbodiimide (C). In this specification, the cyclic carbodiimide (C) refers to a compound having a cyclic structure containing a carbodiimide group (-N=C=N-). In other words, the cyclic carbodiimide (C) is a compound having a carbodiimide group and a linking group bonded to both the first nitrogen atom and the second nitrogen atom in the carbodiimide group, and in which a cyclic structure is formed by the carbodiimide group and the linking group. The cyclic carbodiimide (C) may have one cyclic structure per molecule, or may have two or more cyclic structures.

[0133] A side chain may be bonded to the cyclic structure in the cyclic carbodiimide (C). A part of the cyclic structure may contain a part of an aromatic ring or an aliphatic ring. The cyclic structure may be composed of carbon atoms, or may be composed of carbon atoms and heteroatoms such as oxygen atoms, nitrogen atoms, sulfur atoms, and phosphorus atoms. The number of atoms constituting the cyclic structure in the cyclic carbodiimide (C) is preferably 8 to 50, more preferably 10 to 30, and even more preferably 10 to 20.

[0134] The content of the cyclic carbodiimide (C) in the adhesive composition is 0.1 parts by mass or more and 20 parts by mass or less per 100 parts by mass of the polyester resin (A). By making the content of the cyclic carbodiimide (C) 0.1 parts by mass or more, preferably 0.3 parts by mass or more, more preferably 0.5 parts by mass or more per 100 parts by mass of the polyester resin (A), high solder heat resistance can be maintained even when drying is insufficient. If the content of the cyclic carbodiimide (C) is less than 0.1 parts by mass per 100 parts by mass of the polyester resin (A), the effect of the cyclic carbodiimide (C) will be insufficient, and solder heat resistance may be easily deteriorated when drying is insufficient.

[0135] On the other hand, if the content of the cyclic carbodiimide (C) is excessively high, the cyclic carbodiimide (C) may be more likely to react with other functional groups in the adhesive composition, which may result in a decrease in storage stability. In this case, the cyclic carbodiimide (C) may be less soluble in the adhesive composition, which may result in a decrease in adhesion and deterioration of solder heat resistance. These problems can be easily avoided by setting the content of the cyclic carbodiimide (C) to 20 parts by mass or less, preferably 17 parts by mass or less, and more preferably 15 parts by mass or less per 100 parts by mass of the polyester resin (A).

[0136] When constituting a preferred range of the content of the cyclic carbodiimide (C), the above-mentioned upper and lower limits of the content of the cyclic carbodiimide (C) can be combined arbitrarily. For example, the preferred range of the content of the cyclic carbodiimide (C) may be 0.1 parts by mass or more and 20 parts by mass or less, 0.3 parts by mass or more and 17 parts by mass or less, or 0.5 parts by mass or more and 15 parts by mass or less, relative to 100 parts by mass of the polyester resin (A).

[0137] As the cyclic carbodiimide (C), for example, the cyclic carbodiimide compounds described in JP 2010-285557 A can be used. Furthermore, as the cyclic carbodiimide (C), commercially available products such as "Carbodista (registered trademark) TCC-NP," "Carbodista TCC-FP20M," and "Carbodista TCC-FP10M" manufactured by Teijin Limited can also be used. The adhesive composition may contain one type of cyclic carbodiimide (C), or may contain two or more types of cyclic carbodiimides (C) having different structures.

[0138] The adhesive composition contains a cyclic carbodiimide (C) in addition to the polyester resin (A) and the epoxy compound (B), and is therefore able to suppress peeling of the adherend after heating even when drying is insufficient. Although the reason for this is not entirely clear at present, it is believed that the above-mentioned effect is achieved, for example, for the following reasons.

[0139] When an adhesive composition containing a cyclic carbodiimide (C) is cured, the carboxy group or carboxylic anhydride structure of the polyester resin (A) reacts with the carbodiimide group. This reaction opens the cyclic structure of the cyclic carbodiimide (C). At this time, the first of the two nitrogen atoms of the carbodiimide group bonds with the carboxy group or carboxylic anhydride structure of the polyester resin (A). Furthermore, the second nitrogen atom becomes an isocyanate group (—NCO) at the end of the chain structure formed by ring-opening the cyclic structure. Therefore, it is believed that the cured product of the adhesive composition contains isocyanate groups derived from the carbodiimide group.

[0140] When a cured product of such an adhesive composition absorbs moisture, it is believed that the moisture that has entered the cured product reacts with the isocyanate group and is trapped at the end of the chain structure. Because the moisture trapped at the end of the chain structure is chemically bonded to the chain structure, it is not vaporized by heating in a hot press process, a solder reflow process, or the like. Therefore, it is believed that peeling of the adherend can be suppressed even when a cured product of the adhesive composition is heated in an insufficiently dried state.

[0141] [Inorganic Filler (D)] The adhesive composition may further contain an inorganic filler (D). The content of the inorganic filler (D) is preferably 10 parts by mass or more and 350 parts by mass or less per 100 parts by mass of the total content of the polyester resin (A), the epoxy compound (B), and the cyclic carbodiimide (C).

[0142] Examples of the inorganic filler (D) include non-conductive inorganic fillers such as calcium carbonate particles, titanium oxide particles, aluminum oxide particles, zinc oxide particles, talc particles, and silica particles, and conductive inorganic fillers such as carbon black particles and conductive metal particles. From the viewpoint of more easily imparting conductivity to a cured product of the adhesive composition and easily maintaining the conductivity of the cured product even after soldering, long-term reliability tests, and thermal cycle tests, the adhesive composition preferably contains, as the inorganic filler (D), at least one type of particle selected from the group consisting of talc particles and silica particles, and more preferably contains talc particles.

[0143] From the viewpoint of imparting electrical conductivity to the adhesive composition, it is preferable that the inorganic filler (D) has electrical conductivity. In this case, the volume resistivity of the inorganic filler (D) is 1.0×10 11 The electrical resistance is preferably less than Ω cm. As the conductive inorganic filler (D), it is preferable to use conductive metal particles made of a conductive metal such as gold, platinum, silver, tin, manganese, or indium, or an alloy thereof.

[0144] Furthermore, for example, particles having a multilayer structure including a core particle and a conductive layer provided on the surface of the core particle can also be used as the conductive inorganic filler (D). The core particle may or may not be conductive. For example, nickel particles, silica particles, copper particles, etc. can be used as the core particle. Furthermore, the core particle may be a particle made of a conductive metal or its alloy. The conductive layer may be made of, for example, a conductive metal.

[0145] The conductive layer may be provided on the entire surface of the core particle, or on only a portion of the surface. From the viewpoint of more reliably imparting conductivity to a cured product of the adhesive composition, it is preferable that 70% or more of the surface of the core particle is covered with the conductive layer. Furthermore, from the viewpoints of cost and conductivity, the proportion of the conductive layer is preferably 1 part by mass or more and 40 parts by mass or less, and more preferably 5 parts by mass or more and 30 parts by mass or less, per 100 parts by mass of the core particle.

[0146] The shape of the conductive inorganic filler (D) can take various forms, such as spherical, flake-like, leaf-like, dendritic, plate-like, needle-like, rod-like, and grape-like. From the viewpoints of conductivity and storage stability, the volume-based median diameter (i.e., D50) of the conductive inorganic filler (D) is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 50 μm or less, and particularly preferably 4 μm or more and 15 μm or less. The median diameter of the inorganic filler (D) is a value calculated based on the volume-based particle size distribution obtained by measuring the filler using a laser diffraction / scattering particle size distribution analyzer (e.g., "LS 13320" manufactured by Beckman Coulter, Inc.) with a Tornado dry powder sample module. More specifically, the median diameter of the inorganic filler (D) refers to the particle size at which the integrated volume of the particles, calculated from the fine particle side in the volume-based particle size distribution, is 50% by volume.

[0147] [Imidazole silane (E)] The adhesive composition may contain imidazole silane (E). In this specification, imidazole silane (E) refers to a compound having one or more imidazole ring structures and one or more silane structures. By incorporating imidazole silane (E) into the adhesive composition, adhesion to metals, particularly gold-plated copper foil, can be improved. This is thought to be because the silane structure and imidazole ring structure in imidazole silane (E) exhibit high affinity with metal surfaces. Furthermore, imidazole silane (E) is thought to act as a curing agent for the epoxy compound (B). Therefore, it is thought that the adhesive property-improving effect can be maintained even when the adhesive composition or its cured product is heated, for example, during a reflow process.

[0148] The silane structure in the imidazole silane (E) is preferably a silyl group, and more preferably an alkoxysilyl group, which can further improve the solder heat resistance of the adhesive composition.

[0149] The imidazole ring structure in the imidazole silane (E) may have an imidazole ring having a substituent such as a saturated hydrocarbon group or an unsaturated hydrocarbon group. More specifically, the imidazole ring structure may include an imidazole ring, a 2-alkylimidazole ring, a 2,4-dialkylimidazole ring, a 4-vinylimidazole ring, or the like.

[0150] From the viewpoints of further increasing the adhesive properties of the adhesive composition and more easily imparting electrical conductivity to a cured product of the adhesive composition, the imidazole silane (E) is more preferably a compound represented by the following general formula (E1) or an acid adduct thereof:

[0151]

[0152] R in the general formula (E1) 1 and R 2 R each independently represents a hydrogen atom, a saturated hydrocarbon group, an unsaturated hydrocarbon group, or an aryl group. 1 and R 2 The saturated hydrocarbon group, unsaturated hydrocarbon group and aryl group in the general formula (E1) may have a substituent. 3 and R 4 R each independently represents a hydrogen atom or an alkyl group. 3 At least one of R is an alkyl group. n is an integer of 1 or more and 3 or less. 1 ~R 4 The alkyl group in R preferably has 1 or more and 3 or less carbon atoms. 3 and R 4 The alkyl group in the formula (I) may have a substituent.

[0153] R in the general formula (E1) 5 represents an alkylene group or a group in which a part of the alkylene group is substituted with one or more divalent organic groups selected from the divalent organic groups represented by the following structural formulas (E2) to (E5). 5 The alkylene group in the formula (I) preferably has 1 or more and 10 or less carbon atoms, and more preferably has 3 or more and 7 or less carbon atoms.

[0154]

[0155] R in the structural formula (E2) 6 represents a hydrogen atom or a hydroxy group. 7 represents a hydrogen atom, an alkyl group, or an aryl group. 8 and R 9 R each independently represents a hydrogen atom, an alkyl group, or an aryl group. 7 , R 8 and R 9 The alkyl group and aryl group in the formula (I) may have a substituent.

[0156] The imidazole silane (E) can be suitably synthesized, for example, by reacting an imidazole compound with a 3-glycidoxyalkylsilane compound or the like. The imidazole silane (E) may have a silanol group formed by hydrolysis of an alkoxysilyl group, or may have a polyorganosiloxane structure formed by a dehydration condensation reaction of the silanol group. The imidazole silane (E) may have both a silanol group and a polyorganosiloxane structure.

[0157] Examples of the acid to be added to the compound represented by general formula (E1) include acetic acid, lactic acid, salicylic acid, benzoic acid, adipic acid, phthalic acid, citric acid, tartaric acid, maleic acid, trimellitic acid, phosphoric acid, and isocyanuric acid. These acids may be used alone or in combination of two or more.

[0158] From the viewpoints of electrical conductivity and adhesiveness, the imidazole silane (E) is more preferably a compound represented by the following general formula (E6) or general formula (E7), or an acid adduct thereof.

[0159]

[0160] R in the general formula (E6) and the general formula (E7) 1 and R 2 R each independently represents a hydrogen atom, a saturated hydrocarbon group, an unsaturated hydrocarbon group, or an aryl group. 1 and R 2The saturated hydrocarbon group, unsaturated hydrocarbon group and aryl group in the general formula (E6) and the general formula (E7) may have a substituent. 3 and R 4 R each independently represents a hydrogen atom or an alkyl group. 3 At least one of R is an alkyl group. n is an integer of 1 or more and 3 or less. 1 ~R 4 The alkyl group in R preferably has 1 or more and 3 or less carbon atoms. 3 and R 4 The alkyl group in the formula (I) may have a substituent.

[0161] R in the general formula (E6) and the general formula (E7) 5’ represents an alkylene group. 5’ The number of carbon atoms in the alkylene group in the general formula (E6) and the general formula (E7) is preferably 1 or more and 10 or less, and more preferably 3 or more and 7 or less. 6 represents a hydrogen atom or a hydroxy group.

[0162] More specifically, examples of the imidazole silane (E) include 1-(2-hydroxy-3-trimethoxysilylpropoxypropyl)imidazole, 1-(2-hydroxy-3-triethoxysilylpropoxypropyl)imidazole, 1-(2-hydroxy-3-tripropoxysilylpropoxypropyl)imidazole, 1-(2-hydroxy-3-tributoxysilylpropoxypropyl)imidazole, 1-(2-hydroxy-3-triethoxysilylpropoxypropyl)imidazole, 1-(2-hydroxy-3-triethoxysilylpropoxypropyl)-2-methylimidazole, 1-(2-hydroxy-3-triethoxysilylpropoxypropyl)-4-methylimidazole, 1-(3-oxo-4-trimethoxysilylpropoxypropyl)imidazole, and 1-(3-trimethoxysilylpropylamino)imidazole.

[0163] From the viewpoint of further improving the solubility of the adhesive composition in a solvent and further improving the heat resistance of a cured product of the adhesive composition, it is more preferable that the imidazole silane (E) is an acid adduct of the compound represented by general formula (E6).

[0164] The compound represented by the general formula (E6) can be easily obtained by, for example, reacting an imidazole compound with a 3-glycidoxypropylsilane compound. Examples of the imidazole compound include imidazole, 2-alkylimidazole, 2,4-dialkylimidazole, and 4-vinylimidazole. Examples of the 3-glycidoxypropylsilane compound include 3-glycidoxypropyltrialkoxysilane, 3-glycidoxypropyldialkoxyalkylsilane, and 3-glycidoxypropylalkoxydialkylsilane. Among these, the compound represented by the general formula (E6) is particularly preferably a reaction product of imidazole and 3-glycidoxypropyltrimethoxysilane.

[0165] The compound represented by the general formula (E7) can be easily obtained by reacting an imidazole compound with 3-methacryloyloxypropyltrimethoxysilane or the like.

[0166] The adhesive composition may contain one type of imidazole silane (E), or may contain two or more types of imidazole silane (E). From the viewpoints of electrical conductivity and adhesiveness, the content of the imidazole silane (E) is preferably 0.05 parts by mass or more and 20 parts by mass or less, more preferably 0.1 parts by mass or more and 10 parts by mass or less, and particularly preferably 1 part by mass or more and 5 parts by mass or less, relative to 100 parts by mass of the total content of the polyester resin (A) and the epoxy compound (B).

[0167] [Organic Filler] The adhesive composition may further contain an organic filler. By incorporating an organic filler into the adhesive composition, it is possible to further improve the solder heat resistance, electrical conductivity, and moist heat resistance. Furthermore, since the organic filler has excellent compatibility with the polyester resin (A) and the like, incorporating an organic filler into the liquid adhesive composition can improve the stability of the liquid.

[0168] Examples of organic fillers include (meth)acrylic resin particles, polybutadiene particles, nylon particles, polyolefin particles, polyester particles, polycarbonate particles, polyvinyl alcohol particles, polyvinyl ether particles, polyvinyl butyral particles, silicone rubber particles, polyurethane particles, phenolic resin particles, and polytetrafluoroethylene particles. The adhesive composition may contain one type of organic filler among these organic fillers, or may contain two or more types of organic fillers. From the viewpoint of further enhancing the above-mentioned effects, it is more preferable that the organic filler be one or two or more types of particles selected from the group consisting of silicone particles, polybutadiene particles, (meth)acrylic resin particles, and polyurethane particles.

[0169] The volume-based median diameter of the organic filler is not particularly limited, but from the viewpoint of improving the coatability and making it easier to adjust the coating thickness, it is preferably 0.5 μm or more and 50 μm or less, and more preferably 1 μm or more and 30 μm or less.

[0170] From the viewpoints of adhesiveness, conductivity, and curability, the content of the organic filler is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 5 parts by mass or more and 40 parts by mass or less, and particularly preferably 10 parts by mass or more and 20 parts by mass or less, relative to 100 parts by mass of the total content of the polyester-based resin (A), the epoxy compound (B), and the cyclic carbodiimide (C).

[0171] [Additives] The adhesive composition may contain additives other than the above-mentioned components, as long as the above-mentioned effects are not impaired. Examples of additives include thermoplastic resins other than the polyester-based resin (A), tackifiers, flame retardants, curing agents, curing accelerators, coupling agents, heat aging inhibitors, leveling agents, antifoaming agents, and solvents.

[0172] Examples of thermoplastic resins that can be contained in the adhesive composition include phenoxy resins, polyamide resins, polycarbonate resins, polyphenylene oxide resins, polyurethane resins, polyacetal resins, polyethylene-based resins, polypropylene-based resins, polyvinyl-based resins, etc. The adhesive composition may contain one type of thermoplastic resin among these thermoplastic resins, or may contain two or more types of thermoplastic resins.

[0173] Examples of tackifiers include coumarone-indene resins, terpene resins, terpene-phenol resins, rosin resins, p-t-butylphenol-acetylene resins, phenol-formaldehyde resins, xylene-formaldehyde resins, petroleum-based hydrocarbon resins, hydrogenated hydrocarbon resins, and turpentine-based resins. The adhesive composition may contain one type of tackifier from these tackifiers, or may contain two or more types of tackifiers.

[0174] As the flame retardant, organic flame retardants and inorganic flame retardants can be used. Examples of organic flame retardants include phosphorus-based flame retardants such as melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amido phosphate, ammonium amido polyphosphate, carbamate phosphate, carbamate polyphosphate, aluminum trisdiethylphosphinate, aluminum trismethylethylphosphinate, aluminum trisdiphenylphosphinate, zinc bisdiethylphosphinate, zinc bismethylethylphosphinate, zinc bisdiphenylphosphinate, titanyl bisdiethylphosphinate, titanium tetrakisdiethylphosphinate, titanyl bismethylethylphosphinate, titanium tetrakismethylethylphosphinate, titanyl bisdiphenylphosphinate, and titanium tetrakisdiphenylphosphinate; nitrogen-based flame retardants such as triazine-based compounds such as melamine, melam, and melamine cyanurate, cyanuric acid compounds, isocyanuric acid compounds, triazole-based compounds, tetrazole compounds, diazo compounds, and urea; and silicon-based flame retardants such as silicone compounds and silane compounds.

[0175] Examples of inorganic flame retardants include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, and calcium hydroxide; metal oxides such as tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, and nickel oxide; metal carbonates such as zinc carbonate, magnesium carbonate, calcium carbonate, and barium carbonate; metal borides such as zinc borate; hydrated glass, etc. The adhesive composition may contain one type of these flame retardants, or may contain two or more types of flame retardants.

[0176] The curing agent is used to form a crosslinked structure by reaction with the epoxy compound (B). Examples of the curing agent include acid-based curing agents, basic active hydrogen-based curing agents, polymercaptan-based curing agents, novolac resin-based curing agents, urea resin-based curing agents, and melamine resin-based curing agents. Examples of the acid-based curing agent include amine-based curing agents (e.g., chain aliphatic diamines, chain aliphatic polyamines, alicyclic diamines, and aromatic diamines), polyamidoamine-based curing agents, chain aliphatic polycarboxylic acids, alicyclic polycarboxylic acids, aromatic polycarboxylic acids, and acid anhydrides thereof.

[0177] Examples of the chain aliphatic diamine curing agent include ethylenediamine, 1,3-diaminopropane, 1,4-diaminobutane, hexamethylenediamine, polymethylenediamine, polyetherdiamine, 2,5-dimethylhexamethylenediamine, and trimethylhexamethylenediamine.

[0178] Examples of the chain aliphatic polyamine curing agent include diethylenetriamine, iminobis(hexamethylene)triamine, trihexatetramine, tetraethylenepentamine, aminoethylethanolamine, tri(methylamino)hexane, dimethylaminopropylamine, diethylaminopropylamine, and methyliminobispropylamine.

[0179] Examples of alicyclic diamine curing agents include menthenediamine, isophoronediamine, bis(4-amino-3-methyldicyclohexyl)methane, diaminodicyclohexylmethane, bis(aminomethyl)cyclohexane, N-ethylaminopiperazine, 3,9-bis(3-aminopropyl)2,4,8,10-tetraoxaspiro[5.5]undecane, and hydrogenated metaxylylenediamine.

[0180] Examples of aromatic diamine curing agents include metaphenylenediamine, diaminodiphenylmethane, diaminodiphenylsulfone, diaminodiethyldiphenylmethane, and metaxylylenediamine.

[0181] Examples of the chain aliphatic polycarboxylic acid curing agent and the acid anhydride curing agent include succinic acid, adipic acid, dodecenyl succinic anhydride, polyadipic anhydride, polyazelaic anhydride, and polysebacic anhydride.

[0182] Examples of alicyclic polycarboxylic acid curing agents and acid anhydride curing agents include methyltetrahydrophthalic acid, methylhexahydrophthalic acid, methylhimic acid, hexahydrophthalic acid, tetrahydrophthalic acid, trialkyltetrahydrophthalic acid, methylcyclodicarboxylic acid, and acid anhydrides thereof.

[0183] Examples of aromatic polycarboxylic acid curing agents and acid anhydride curing agents include phthalic acid, trimellitic acid, pyromellitic acid, benzophenone tetracarboxylic acid, ethylene glycol glycol bistrimellitic acid, glycerol tristrimellitic acid, and acid anhydrides thereof.

[0184] Examples of basic active hydrogen curing agents include dicyandiamide and organic acid dihydrazide. Examples of polymercaptan curing agents include mercaptoated epoxy resins and mercaptopropionic acid esters. Examples of novolac resin curing agents include phenol novolac curing agents and cresol novolac curing agents.

[0185] The adhesive composition may contain one type of curing agent from the above-mentioned curing agents, or may contain two or more types of curing agents. From the viewpoint of further improving adhesiveness and heat resistance, the functional group equivalent of the curing agent in the adhesive composition is preferably 0.2 molar equivalents or more and 2.5 molar equivalents or less, and more preferably 0.4 molar equivalents or more and 2.0 molar equivalents or less, relative to 1 molar equivalent of the epoxy group of the epoxy compound (B).

[0186] The curing accelerator is a component used for the purpose of accelerating the reaction of the epoxy compound (B). Examples of the curing accelerator that can be used include tertiary amine curing accelerators, tertiary amine salt curing accelerators, and imidazole curing accelerators.

[0187] Examples of tertiary amine curing accelerators include benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, tetramethylguanidine, triethanolamine, N,N'-dimethylpiperazine, triethylenediamine, and 1,8-diazabicyclo[5.4.0]undecene.

[0188] Examples of the tertiary amine salt curing accelerator include formate, octylate, p-toluenesulfonate, o-phthalate, phenolate, and phenol novolac resin salt of 1,8-diazabicyclo[5.4.0]undecene; and formate, octylate, p-toluenesulfonate, o-phthalate, phenolate, and phenol novolac resin salt of 1,5-diazabicyclo[4.3.0]nonene.

[0189] Examples of the imidazole curing accelerator include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-methyl-4-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2' -undecylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]-ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]-ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-phenyl-4,5-dihydroxymethylimidazole, and 2-phenyl-4-methyl-5-hydroxymethylimidazole.

[0190] The adhesive composition may contain one type of curing accelerator among the above-mentioned curing accelerators, or may contain two or more types of curing accelerators. From the viewpoints of adhesiveness and heat resistance, the content of the curing accelerator is preferably 1 part by mass or more and 10 parts by mass or less, and more preferably 2 parts by mass or more and 5 parts by mass or less, per 100 parts by mass of the epoxy compound (B).

[0191] Examples of coupling agents include silane coupling agents, titanate coupling agents, aluminate coupling agents, and zirconium coupling agents. Examples of silane coupling agents include vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, and imidazole silane. The adhesive composition may contain one of these coupling agents, or two or more of them.

[0192] Examples of the heat aging inhibitor include phenol-based antioxidants, sulfur-based antioxidants, and phosphorus-based antioxidants. Examples of the phenol-based antioxidant include 2,6-di-tert-butyl-4-methylphenol, n-octadecyl-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate, and tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane.

[0193] Examples of sulfur-based antioxidants include dilauryl-3,3'-thiodipropionate and dimyristyl-3,3'-dithiopropionate. Examples of phosphorus-based antioxidants include trisnonylphenyl phosphite and tris(2,4-di-tert-butylphenyl)phosphite. The adhesive composition may contain one type of heat-aging inhibitor from these heat-aging inhibitors, or may contain two or more types of heat-aging inhibitors.

[0194] It is preferable that the adhesive composition further contains a solvent. In this case, a liquid adhesive composition can be obtained. By making the adhesive composition liquid, it is possible to smoothly apply the adhesive composition to an adherend and form an adhesive layer, and it is possible to easily form an adhesive layer of a desired thickness. More specifically, the liquid adhesive composition may be a solution in which solids are dissolved in a solvent, or a dispersion in which solids are dispersed in a solvent.

[0195] Examples of the solvent include alcohol-based solvents, ketone-based solvents, aromatic hydrocarbon-based solvents, ester-based solvents, and aliphatic hydrocarbon-based solvents. Examples of the alcohol-based solvent include methanol, ethanol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol, n-butyl alcohol, benzyl alcohol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diacetone alcohol.

[0196] Examples of ketone solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, and isophorone. Examples of aromatic hydrocarbon solvents include toluene, xylene, ethylbenzene, and mesitylene. Examples of ester solvents include methyl acetate, ethyl acetate, ethylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate. Examples of aliphatic hydrocarbon solvents include hexane, heptane, cyclohexane, and methylcyclohexane. The adhesive composition may contain one or more of these solvents.

[0197] The polyester resin (A) has the property of being easily soluble in protic solvents. Therefore, from the viewpoint of more easily dissolving the polyester resin (A) in a solvent, it is preferable that the adhesive composition contains an alcohol-based solvent. When the adhesive composition contains a solvent, from the viewpoint of workability including film-forming ability, the solids concentration of the adhesive composition is preferably 3% by mass or more and 80% by mass or less, and more preferably 10% by mass or more and 50% by mass or less.

[0198] [Method of Using the Adhesive Composition] The method of using the adhesive composition is not particularly limited, and the adhesive composition can be used in various embodiments. For example, the adhesive composition can be used as an adhesive for bonding two adherends. Furthermore, for example, a laminate containing a cured product of the adhesive composition can be obtained by applying the adhesive composition to the surface of an adherend and then curing it. The adherend to which the adhesive composition is applied may be made of a metal material such as copper, aluminum, or stainless steel, or may be made of a polymer material such as a polyimide resin, polyether ether ketone resin, polyphenylene sulfide resin, modified polyimide resin, or liquid crystal polymer. The shape of the adherend is not particularly limited, and various embodiments are possible. More detailed uses of the adhesive composition will be described later.

[0199] [Water Absorption of Cured Product] When a cured product of the adhesive composition is immersed in water at 23°C for 24 hours, the water absorption is preferably 3% or less. In this case, the cured product is less likely to absorb moisture, and the long-term moist heat resistance of the cured product can be further improved. The water absorption of the cured product can be controlled, for example, by adjusting the ratio of hydrophobic repeating units to hydrophilic repeating units contained in the polyester-based resin (A). More specifically, when the polyester-based resin (A) is a polyester polyamide or polyester polyurethane, the water absorption of the cured product can be reduced by increasing the ratio of relatively highly hydrophobic polyester moieties.

[0200] (Bonding Film) A bonding film can be obtained by providing an uncured product of the adhesive composition or a semi-cured product obtained by partially curing the adhesive composition on a release film. The bonding film has an adhesive layer and a release film provided on one or both sides of the adhesive layer and configured to be peelable from the adhesive layer. The adhesive layer in the bonding film is composed of the adhesive composition or a semi-cured product obtained by partially curing the adhesive composition.

[0201] The bonding film has an adhesive layer composed of an uncured adhesive composition or a semi-cured product of the adhesive composition. The adhesive layer is provided on a release film. Therefore, after the adhesive layer is attached to an adherend, the release film can be peeled off from the adhesive layer, and another adherend can be attached to the adhesive layer. Furthermore, because the adhesive layer is composed of an uncured or semi-cured product of the adhesive composition, the curing reaction can be further promoted by heating or the like. Therefore, two adherends can be bonded by curing the adhesive layer while the adhesive layer is interposed between them.

[0202] Furthermore, as described above, the adhesive composition can suppress peeling of the adherend after heating even when the adhesive is not sufficiently dried. Therefore, with the bonding film, even when two adherends are bonded together when the adhesive layer is not sufficiently dried, peeling of the adherend from the cured product can be suppressed when the cured product is heated. Bonding films with such properties are suitable for the production of FPCs and FPC-related products.

[0203] The release film in the bonding film is configured so that it can be peeled off from the adhesive layer without damaging the adhesive layer. Examples of the release film include polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release-treated paper, polyolefin resin-coated paper, polymethylpentene (TPX) film, and fluorine-based resin film. The thickness of the release film is preferably 20 μm or more and 100 μm or less.

[0204] The thickness of the adhesive layer is preferably 5 μm or more and 100 μm or less, more preferably 5 μm or more and 70 μm or less, even more preferably 5 μm or more and 50 μm or less, and particularly preferably 10 μm or more and 40 μm or less. The adhesive layer preferably does not substantially contain a solvent. The term "adhesive layer substantially free of solvent" includes both a state in which the adhesive layer does not contain any solvent at all and a state in which the adhesive layer contains a solvent to the extent that it does not interfere with maintaining the shape of the adhesive layer and attaching it to the adherend.

[0205] The method for producing the bonding film is not particularly limited, and known methods can be appropriately adopted. For example, when producing a bonding film using an adhesive composition containing a solvent, the adhesive composition is applied to the surface of a release film, and then at least a portion of the solvent is removed from the adhesive composition on the release film to form an adhesive layer on the release film, thereby obtaining a bonding film. The method for applying the adhesive composition to the release film may be selected from known application methods such as gravure coating, kiss coating, die coating, lip coating, comma coating, blade coating, roll coating, knife coating, spray coating, bar coating, spin coating, and dip coating.

[0206] The method for removing the solvent from the adhesive composition is not particularly limited, and can be, for example, a method of drying the adhesive composition by various heating methods such as hot air drying, far-infrared heating, high-frequency induction, etc. In this case, the drying temperature for the adhesive composition is preferably 40°C or higher and 250°C or lower, and more preferably 70°C or higher and 170°C or lower.

[0207] (Laminate with adhesive layer) A laminate with an adhesive layer can be obtained by providing an uncured or semi-cured product of the adhesive composition on a substrate layer. The laminate with an adhesive layer has an adhesive layer and a substrate layer adhered to at least one surface of the adhesive layer. The adhesive layer in the laminate with an adhesive layer is composed of the adhesive composition or a semi-cured product obtained by partially curing the adhesive composition.

[0208] The laminate with an adhesive layer has an adhesive layer made of an uncured adhesive composition or a semi-cured product of the adhesive composition. The adhesive layer is provided on a substrate layer. Therefore, after the adhesive layer is attached to the adherend, the adhesive layer can be further cured to bond the laminate with the adhesive layer to the adherend.

[0209] Furthermore, as described above, the adhesive composition can suppress peeling of the adherend after heating even when the adhesive composition is insufficiently dried. Therefore, with the laminate with the adhesive layer, even when the adherend is bonded in a state where the adhesive layer is insufficiently dried, peeling of the adherend from the cured product can be suppressed when the cured product is heated. A laminate with an adhesive layer having such properties is suitable for the production of FPCs and FPC-related products.

[0210] The substrate layer in the adhesive layer-attached laminate is preferably a resin film, more preferably an electrically insulating resin film. Examples of resins that can be used to form the resin film include polyimide resins, modified polyimide resins, mixed resins of polyimide resins and modified polyimide resins, liquid crystal polymers, and fluorine-based resins. Among these, the resin that forms the resin film is preferably a polyimide resin, modified polyimide resin, or mixed resins of polyimide resins and modified polyimide resins, more preferably a polyimide resin. The resin film may also contain additives as needed. The surface of the substrate layer to which the adhesive layer is attached may be surface-treated. A laminate with an adhesive layer, which includes an electrically insulating resin film and an electrically insulating adhesive layer provided on the resin film, is sometimes called a coverlay film.

[0211] The thickness of the substrate layer and the thickness of the adhesive layer in the laminate with an adhesive layer may be appropriately set depending on the application of the laminate with an adhesive layer. For example, from the viewpoint of improving the electrical properties of the laminate with an adhesive layer, it is preferable to make the thickness of the substrate layer thin. For example, the thickness of the substrate layer is preferably 3 μm or more and 125 μm or less.

[0212] Furthermore, the thickness of the adhesive layer in the laminate with the adhesive layer is preferably 5 μm or more and 100 μm or less, more preferably 5 μm or more and 70 μm or less, even more preferably 5 μm or more and 50 μm or less, and particularly preferably 10 μm or more and 40 μm or less.

[0213] The ratio of the thickness of the adhesive layer to the thickness of the base layer is preferably from 1 to 10, and more preferably from 1 to 5. Furthermore, the thickness of the adhesive layer is preferably greater than the thickness of the base layer.

[0214] The laminate with the adhesive layer may have a release film on the adhesive layer, if necessary. The release film provided on the adhesive layer is the same as the release film used in the bonding film described above.

[0215] The method for producing the laminate with an adhesive layer is the same as the method for producing the bonding film described above. That is, for example, when producing the laminate with an adhesive layer using an adhesive composition containing a solvent, the adhesive composition is applied to the surface of the base layer, and then at least a part of the solvent is removed from the adhesive composition on the base layer to form an adhesive layer on the base layer, thereby obtaining the laminate with the adhesive layer.

[0216] (Electromagnetic wave shielding material) The conductive adhesive composition can also be used to produce an electromagnetic wave shielding material. The electromagnetic wave shielding material has, for example, a conductive adhesive layer, and the conductive adhesive layer is composed of the conductive adhesive composition or a semi-cured product thereof.

[0217] The electromagnetic wave shielding material has a conductive adhesive layer composed of an uncured adhesive composition or a semi-cured product of the adhesive composition. Therefore, the conductive adhesive layer can be applied to a desired portion of the surface of an adherend, including a ground wiring, and then further cured by heat pressing or the like to form a conductive cured material layer on the adherend. The conductive cured material layer thus formed is electrically connected to the ground wiring, thereby reducing electromagnetic noise entering the printed wiring board from the outside and electromagnetic noise generated by the printed wiring board.

[0218] The electromagnetic wave shielding material may be composed of only a conductive adhesive layer, or may be composed of two or more layers including a conductive adhesive layer. For example, the electromagnetic wave shielding material may have a conductive adhesive layer and a release film provided on one or both sides of the conductive adhesive layer. Alternatively, the electromagnetic wave shielding material may have, for example, a conductive adhesive layer and a conductor layer provided on one side of the conductive adhesive layer. In this case, the conductive cured product layer electrically connects the conductor layer to the ground wiring of the adherend, thereby further enhancing the effect of reducing electromagnetic noise.

[0219] The electromagnetic wave shielding material may also have a conductive adhesive layer and a protective layer provided on one side of the conductive adhesive layer. By providing a protective layer on the conductive adhesive layer in this way, the conductive cured material layer is less susceptible to damage due to wear and tear. As a result, the electromagnetic noise shielding effect can be maintained for a longer period of time.

[0220] The conductive adhesive layer is preferably composed of, for example, an adhesive composition containing a conductive inorganic filler (D), or a semi-cured or cured product thereof. The thickness of the conductive adhesive layer is not particularly limited, but is preferably 3 μm or more and 30 μm or less from the viewpoints of conductivity and electrical connection with the ground wiring.

[0221] The protective layer may take various forms as long as it has electrical insulation properties. For example, the protective layer may be composed of an electrically insulating adhesive, resin film, or the like. Alternatively, the protective layer may be composed of the adhesive composition or a semi-cured product thereof that does not have electrical conductivity. The protective layer may contain, as necessary, a curing accelerator, a tackifier, an antioxidant, a pigment, a dye, a plasticizer, an ultraviolet absorber, an antifoaming agent, a leveling agent, a filler, a flame retardant, a viscosity modifier, an antiblocking agent, and the like. Furthermore, two or more protective layers composed of different materials may be provided on the conductive adhesive layer.

[0222] The method for producing the electromagnetic wave shielding material is the same as the method for producing the bonding film described above. For example, when a protective layer is formed using the adhesive composition having electrical insulation properties and a conductive adhesive layer is formed using the adhesive composition having electrical conductivity, the following method can be adopted. First, an adhesive composition for forming a protective layer is applied to a release film. The adhesive composition is then dried and cured as necessary to form a protective layer on the release film. Next, an adhesive composition for forming a conductive adhesive layer is applied to the protective layer. The adhesive composition on the protective layer is then dried, thereby forming a conductive adhesive layer on the protective layer.

[0223] (Laminate) The adhesive composition can also be used to produce a laminate containing a cured product of the adhesive composition. The laminate has a cured product layer made of the cured product of the adhesive composition. The thickness of the cured product layer can be appropriately set depending on the application of the laminate. The thickness of the cured product layer is preferably 5 μm or more and 100 μm or less, more preferably 5 μm or more and 70 μm or less, even more preferably 5 μm or more and 50 μm or less, and particularly preferably 10 μm or more and 40 μm or less.

[0224] The laminate may be a flexible copper-clad laminate including a resin film, a cured product layer provided on at least one side of the resin film, and a copper foil provided on the cured product layer. The adhesive composition has excellent adhesion to copper-containing articles. Therefore, a flexible copper-clad laminate obtained using the adhesive composition has excellent durability and the copper foil is less likely to peel off.

[0225] The resin film in the flexible copper-clad laminate may be composed of, for example, a polyimide resin, a modified polyimide resin, a mixed resin of a polyimide resin and a modified polyimide resin, a liquid crystal polymer, a fluorine-based resin, etc. Among these resins, the resin film is preferably composed of a polyimide resin, a modified polyimide resin, or a mixed resin of a polyimide resin and a modified polyimide resin. The copper foil in the flexible copper-clad laminate may be an electrolytic copper foil or a rolled copper foil. The copper foil may also be plated with other metals or alloys. The thickness of the cured layer in the flexible copper-clad laminate is preferably 5 μm or more and 50 μm or less, and more preferably 10 μm or more and 40 μm or less.

[0226] The method for producing the laminate is not particularly limited, and known methods can be appropriately adopted. For example, when a laminate including a first adherend and a second adherend is produced using a solvent-containing adhesive composition, the adhesive composition is applied to the surface of the first adherend, and then the adhesive composition is dried to form an adhesive layer on the first adherend. Next, the surface of the adhesive layer and the second adherend are brought into surface contact, and lamination is performed at a temperature of, for example, 80°C or higher and 150°C or lower. This allows for the production of a laminate including the first adherend, the adhesive layer provided on the first adherend, and the second adherend provided on the adhesive layer.

[0227] The laminate is then heated and pressed to cure the adhesive layer, forming a cured layer. The conditions for performing the heat press are not particularly limited as long as they can bond the adhesive layer to the adherend. For example, the heating temperature in the heat press can be appropriately set within a range of 150°C or higher and 200°C or lower. The pressure in the heat press can be appropriately set within a range of 1 MPa or higher and 3 MPa or lower. The pressing time in the heat press can be appropriately set within a range of 1 minute or higher and 60 minutes or lower.

[0228] After the heat pressing, the laminate may be heated as needed to perform after-curing, further hardening the adhesive layer. The heating temperature during after-curing may be appropriately set, for example, within the range of 100° C. to 200° C. The heating time during after-curing may be appropriately set, for example, within the range of 30 minutes to 4 hours.

[0229] Examples of the adhesive composition are described below. In these examples, the adhesive composition was prepared using the following raw materials.

[0230] (Polyester Resin (A)) In this example, polyester polyamides a1 and a2 and polyester polyurethanes a3 and a4 were used as the polyester resin (A). These were prepared by the following methods.

[0231] [Polyester Polyamide a1] 7 parts by weight of dimer acid, 406 parts by weight of azelaic acid, 364 parts by weight of isophorone diamine, and 120 parts by weight of distilled water were placed in a flask equipped with a stirrer, a reflux dehydrator, and a distillation column. The flask was heated, and the temperature of the contents was increased to 120°C to distill off water. The flask was then further heated, and the temperature of the contents was increased to 240°C at a rate of 20°C / hour. After maintaining this temperature for 1 hour, 200 parts by weight of azelaic acid, 125 parts by weight of neopentyl glycol, and 2.1 parts by weight of tetrabutoxy titanate as an esterification catalyst were added to the reaction product in the flask. The addition of these raw materials caused the temperature of the contents of the flask to decrease to 150°C.

[0232] The flask was then heated again to raise the temperature of the contents to 220°C. The reaction was continued by maintaining this temperature until the amine value reached 7.6 mgKOH / g. Thus, polyester polyamide a1 in pellet form was obtained. The acid value of polyester polyamide a1 was 1.3 mgKOH / g. The acid value of polyester resin (A) was measured and calculated by potentiometric titration in accordance with JIS K 2501 (2003).

[0233] [Polyester polyamide a2] The method for producing polyester polyamide a2 was the same as the method for producing polyester polyamide a1 described above, except that the reaction was continued until the amine value reached 4.3 mg KOH / g. The acid value of polyester polyamide a2 was 0.7 mg KOH / g.

[0234] [Polyester Polyurethane a3] 600 parts by mass of a polyester adhesive ("PES-360HVXM30" manufactured by Toagosei Co., Ltd.), 100 parts by mass of toluene, and 20 parts by mass of neopentyl glycol were placed in a flask equipped with a stirrer, a reflux dehydration apparatus, and a distillation tube. The flask was heated to raise the temperature of the contents to 120°C, and 100 parts by mass of the solvent containing water was distilled off, after which the temperature of the contents was lowered to 105°C. Thereafter, 0.4 parts by mass of 2,2-dimethylolpropionic acid was added to the flask and dissolved in the contents.

[0235] Next, 34 parts by mass of hexamethylene diisocyanate was added to the flask. 30 minutes after the addition of hexamethylene diisocyanate, 0.2 parts by mass of dibutyltin dilaurate was added to the flask, and the reaction was continued for 6 hours. The contents of the flask were then diluted with toluene and 2-propanol to adjust the solids concentration to 30% by mass. This yielded a solution containing polyester polyurethane a3. The polyester polyurethane a3 had a number average molecular weight of 36,000 and an acid value of 2 mgKOH / g.

[0236] [Polyester Polyurethane a4] 600 parts by mass of a polyester adhesive ("PES-360HVXM30" manufactured by Toagosei Co., Ltd.), 100 parts by mass of toluene, and 30 parts by mass of 2-butyl-2-ethyl-1,3-propanediol were placed in a flask equipped with a stirrer, a reflux dehydrator, and a distillation tube. The flask was heated to raise the temperature of the contents to 120°C, and 100 parts by mass of the solvent containing water was distilled off, after which the temperature of the contents was lowered to 105°C. Thereafter, 0.4 parts by mass of 2,2-bis(hydroxymethyl)propionic acid was added to the flask and dissolved in the contents.

[0237] Next, 42 parts by mass of norbornane diisocyanate (Cosmonate (registered trademark) NBDI (registered trademark) manufactured by Mitsui Chemicals, Inc.) was added to the flask. 30 minutes after the addition of norbornane diisocyanate, 0.2 parts by mass of dibutyltin dilaurate was added to the flask. The reaction was then continued until a predetermined molecular weight was reached, and the contents of the flask were then diluted with toluene and 2-propanol to adjust the solids concentration to 30% by mass. This yielded a solution containing polyester polyurethane a4. The polyester polyurethane a4 had a number average molecular weight of 35,000 and an acid value of 2 mgKOH / g.

[0238] (Epoxy Compound (B)) The epoxy compounds (B) used in this example are as follows: Epoxy compound b1: Trisphenolmethane type epoxy resin ("jER (registered trademark) 1032H60" manufactured by Mitsubishi Chemical Corporation) Epoxy compound b2: Bisphenol A novolac type epoxy resin ("EPICLON (registered trademark) N-865" manufactured by DIC Corporation) Epoxy compound b3: Bisphenol A type epoxy resin ("jER 1055" manufactured by Mitsubishi Chemical Corporation)

[0239] (Cyclic Carbodiimide (C)) The cyclic carbodiimides (C) used in this example are as follows: Cyclic carbodiimide c1: "Carbodista TCC-FP10M" manufactured by Teijin Limited Cyclic carbodiimide c2: "Carbodista TCC-NP" manufactured by Teijin Limited

[0240] (Inorganic Filler (D)) The inorganic filler d1 used in this example has electrical conductivity. More specifically, the inorganic filler d1 is copper powder ("FCC-115A" manufactured by Fukuda Metal Foil & Powder Co., Ltd.).

[0241] (Other Components) The other components used in this example are as follows.

[0242] Imidazole compound e1: 1-(2-hydroxy-3-trimethoxysilylpropoxypropyl)imidazole

[0243] Flame retardant: phosphinic acid metal salt-based flame retardant ("Exolit (registered trademark) OP935" manufactured by Clariant) Curing accelerator: imidazole-based curing accelerator ("Curesol (registered trademark) C11-Z" manufactured by Shikoku Chemicals Corporation) Solvent: mixed solvent obtained by mixing 20 parts by mass of methyl ethyl ketone and 20 parts by mass of 2-propanol with 100 parts by mass of toluene Acyclic carbodiimide: "Carbodilite (registered trademark) V-05" manufactured by Nisshinbo Inc.

[0244] [Polyamide] 485 parts by mass of dimer acid, 100 parts by mass of hexamethylenediamine, and 120 parts by mass of distilled water were placed in a flask equipped with a stirrer, a reflux dehydrator, and a distillation tube. The flask was heated to raise the temperature of the contents to 120°C, and water was distilled off. The temperature of the contents was then raised to 240°C at a rate of 20°C / hour. This temperature was maintained for 3 hours to continue the reaction, yielding polyamide pellets. The amine value of the polyamide was 4.5 mgKOH / g. The amine value of the polyamide was measured and calculated by potentiometry in accordance with JIS K 7237 (1995).

[0245] (Examples 1 to 10 and Comparative Examples 1 to 4) The above raw materials were added to a flask equipped with a stirrer in the proportions shown in Tables 1 and 2, and the flask was then heated to raise the temperature of the contents to 60°C. The contents were then stirred for 6 hours while maintaining the temperature, thereby dissolving the polyester resin (A), polyamide, epoxy compound (B), cyclic carbodiimide (C), acyclic carbodiimide, imidazole silane (E), and curing accelerator in the solvent, and dispersing the inorganic filler (D) and flame retardant. In this manner, liquid adhesive compositions were prepared. The blend amounts of polyester resin (A) and polyamide in Tables 1 and 2 refer to the amounts of solids (i.e., the amounts of polyester resin (A) or polyamide excluding the solvent).

[0246] Next, using the adhesive compositions of the Examples and Comparative Examples, a test piece A for evaluating flame retardancy (hereinafter referred to as "test piece A"), a bonding film B and a test piece C for evaluating adhesion (hereinafter referred to as "test piece C"), and a test piece D for evaluating adhesion (hereinafter referred to as "test piece D") were prepared by the following methods.

[0247] [Flame Retardancy Evaluation Specimen A] As shown in Fig. 1, the flame retardancy evaluation specimen A has a cured material layer 1 made of a cured product of the adhesive composition, and polyimide films 2 (2a, 2b) laminated on both sides of the cured material layer 1. The thickness of the cured material layer 1 is 15 µm, and the thickness of the polyimide film 2 is 25 µm.

[0248] The test piece A was prepared as follows: First, the adhesive composition was applied with a roll coater to the surface of the first polyimide film 2a of the two polyimide films 2. The adhesive composition on the polyimide film 2a was then dried for 3 minutes in an oven set at 100°C, thereby preparing a coverlay film having the polyimide film 2a and an adhesive layer laminated on the polyimide film 2a.

[0249] Next, a second polyimide film 2b was superimposed on the adhesive layer of the coverlay film, and a thermal lamination process was performed. The heating temperature in the thermal lamination process was 120°C, the pressure was 0.4 MPa, and the lamination speed was 0.5 m / min. The laminate of the coverlay film and the polyimide film 2b was then subjected to a heat press process under conditions of a temperature of 170°C, a pressure of 3 MPa, and a heating time of 30 minutes, thereby curing the adhesive layer to form a cured layer 1 and bonding the cured layer 1 and the polyimide film 2b together. The laminate thus obtained was cut to a predetermined size to obtain test piece A.

[0250] [Bonding Film B] As shown in FIG. 2, bonding film B has a release film 3 and an adhesive layer 10 provided on the release film 3. The release film 3 is made of polyethylene terephthalate. The release film 3 has a thickness of 35 μm. The adhesive layer 10 has a thickness of 25 μm. The adhesive layer 10 is made of an adhesive composition 100 or a semi-cured product thereof.

[0251] The bonding film B is obtained by applying the adhesive composition onto the release film 3 with a roll coater and then drying it at a temperature of 100° C. for 3 minutes.

[0252] [Test piece C for adhesiveness evaluation] As shown in Fig. 3, the test piece C for adhesiveness evaluation has a polyimide film 2, a cured material layer 1 provided on the polyimide film 2, and a copper foil 4 provided on the cured material layer 1. The polyimide film 2 and the copper foil 4 are bonded together via the cured material layer 1. The thickness of the polyimide film 2 is 25 µm, and the thickness of the cured material layer 1 is 15 µm. The copper foil 4 used was a rolled copper foil with a thickness of 35 µm.

[0253] The test piece C was prepared as follows: First, the adhesive composition was applied to a polyimide film 2 using a roll coater. Then, the adhesive composition on the polyimide film 2 was dried for 2 minutes in an oven set at a temperature of 120°C, thereby forming an adhesive layer on the polyimide film 2.

[0254] Next, the adhesive layer and copper foil 4 were bonded together so that the adhesive layer and the glossy surface of the copper foil 4 were in contact. This laminate was subjected to a thermal lamination process to cure the adhesive layer, form a cured material layer 1, and bond the cured material layer 1 and the copper foil 4 together. The heating temperature in the thermal lamination process was 150°C, the pressure was 0.3 MPa, and the lamination speed was 1 m / min. The laminate was then heated in an oven set at 160°C for 2 hours to perform after-cure, thereby obtaining test piece C.

[0255] 4, the adhesiveness evaluation specimen D has a metal plate 5, a conductive cured material layer 11 provided on the metal plate 5, and a flexible printed wiring board 6 provided on the conductive cured material layer 11, and the metal plate 5 and the flexible printed wiring board 6 are bonded together via the conductive cured material layer 11. The metal plate 5 of the specimen D is a plate material made of SUS304 and having a thickness of 300 μm, and a nickel plating film (not shown) is formed on the surface of the plate material.

[0256] The flexible printed wiring board 6 of test piece D includes a polyimide film 61, a circuit pattern 62 provided on a first surface 611 of the surfaces of the polyimide film 61, and a coverlay 63 covering the first surface 611 of the polyimide film and the circuit pattern 62. The polyimide film 61 has a thickness of 25 μm. The circuit pattern 62 is made of copper. The coverlay 63 has a thickness of 37.5 μm. The coverlay 63 also has a through-hole 631 with a diameter of 1 mm at a position overlapping the circuit pattern 62.

[0257] A portion of the circuit pattern 62 is exposed inside the through-hole 631. The through-hole 631 is filled with a conductive cured material layer 11, and the conductive cured material layer 11 in the through-hole 631 is in contact with the circuit pattern 62. In this way, the conductive cured material layer 11 and the circuit pattern 62 are in contact with each other inside the through-hole 631, thereby electrically connecting the metal plate 5 and the flexible printed wiring board 6.

[0258] The method for producing the test piece D is as follows. First, a bonding film B having a conductive adhesive layer was prepared, and the bonding film B was attached to the metal plate 5 so that the adhesive layer 10 of the bonding film B came into contact with the nickel plating film of the metal plate 5. This laminate was subjected to a thermal lamination process to bond the metal plate 5 and the bonding film B. The heating temperature in the thermal lamination process was 150°C, the pressure was 0.3 MPa, and the lamination speed was 1 m / min.

[0259] Next, the release film 3 was peeled off from the laminate to expose the adhesive layer 10. Thereafter, the laminate and a flexible printed wiring board 6 were bonded together such that the adhesive layer 10 of the laminate came into contact with the coverlay 63 of the flexible printed wiring board 6. This laminate was subjected to a heat press treatment under conditions of a heating temperature of 150°C, a pressure of 0.3 MPa, and a heating time of 5 minutes, thereby curing the adhesive layer 10 to form a conductive cured material layer 11 and bonding the flexible printed wiring board 6 and the metal plate 5 via the conductive cured material layer 11. Thereafter, the laminate was heated for 2 hours in an oven set at a temperature of 160°C to perform after-curing, and a test piece D was obtained.

[0260] Using the test piece A, bonding film B, test piece C and test piece D obtained as described above, the various properties shown in Tables 1 and 2 were evaluated. The evaluation methods for each property were as follows.

[0261] (Water Absorption of Cured Product) To measure the water absorption of the cured product, a cured product for water absorption measurement was first prepared using the bonding film B shown in FIG. 2. Specifically, two bonding films B (see FIG. 2) were bonded together so that the adhesive layers 10 were in contact with each other, and then the release film 3 of one of the bonding films B was peeled off to expose the adhesive layer 10. This operation was repeated to laminate four adhesive layers 10 between the release films 3. Thereafter, a heat press treatment was performed under conditions of a heating temperature of 150°C, a pressure of 3 MPa, and a heating time of 5 minutes to cure the four adhesive layers 10 and bond adjacent adhesive layers 10 to each other. After peeling the release film 3 from the cured product of this adhesive layer 10, the cured product was heated at a temperature of 160°C for 2 hours to obtain a cured product having a thickness of 100 μm.

[0262] The water absorption of the cured product thus obtained was measured in accordance with JIS K 7114 (2001). Tables 1 and 2 show the water absorption when the cured product was immersed in water at 23°C for 24 hours.

[0263] (Peel Adhesion Strength) Test piece C shown in FIG. 3 was used to measure peel adhesion strength. The peel adhesion strength was measured in accordance with JIS C 6481 "Test Methods for Copper-Clad Laminates for Printed Wiring Boards." In this example, the peel adhesion strength of test piece C was measured in the initial state and after a high-temperature, high-humidity test. More specifically, in measuring the peel adhesion strength in the initial state, test piece C prepared by the above-mentioned method was used, and the 180° peel adhesion strength (unit: N / cm) was measured when peeling the copper foil 4 from the polyimide film 1. The temperature during measurement was 23°C, and the pulling speed was 50 mm / min.

[0264] Furthermore, in measuring the peel adhesive strength after the high-temperature, high-humidity test, the high-temperature, high-humidity test was carried out by storing test piece C in a constant temperature and humidity chamber at a temperature of 85°C and a relative humidity of 85% RH for 1,000 hours. Using test piece C after the high-temperature, high-humidity test, the peel adhesive strength was measured in the same manner as described above.

[0265] In the "Peel Adhesion Strength" column of Tables 1 and 2, the symbol "A" was entered when the peel adhesion strength was 5.0 N / cm or more, the symbol "B" was entered when it was more than 3.5 N / cm and less than 5.0 N / cm, and the symbol "C" was entered when it was 3.5 N / cm or less.

[0266] (Soldering Heat Resistance) Test piece C shown in Fig. 3 was used to evaluate the soldering heat resistance. The soldering heat resistance test was performed in accordance with JIS C 6481 (1996). In this example, the soldering heat resistance test was performed using test piece C in an absolute dry state, after 24 hours of humidification, and after 72 hours of humidification, and the soldering heat resistance was evaluated based on the appearance of test piece C after the test.

[0267] Specifically, in the evaluation of bone-dry test specimen C, the test specimen C obtained by the above-mentioned method was pretreated at 105±2°C, and immediately thereafter, the test specimen C was floated in a solder bath at 260°C for 60 seconds to perform a soldering heat resistance test. In the evaluation of test specimen C after 24 hours of humidification, the test specimen C was pretreated at 105±2°C, and then stored in an environment at a temperature of 30°C and a relative humidity of 60%RH for 24 hours to allow the test specimen C to absorb moisture. The test specimen C was then floated in a solder bath at 260°C for 60 seconds to perform a soldering heat resistance test. In the evaluation of test specimen C after 72 hours of humidification, the test specimen C was pretreated at 105±2°C, and then stored in an environment at a temperature of 30°C and a relative humidity of 60%RH for 72 hours to allow the test specimen C to absorb moisture. The test specimen C was then floated in a solder bath at 260°C for 60 seconds to perform a soldering heat resistance test.

[0268] After the soldering heat resistance test was performed as described above, the appearance of test piece C was visually observed. In the "Soldering Heat Resistance" column of Tables 1 and 2, the symbol "A" was entered if no abnormalities were observed in the appearance of test piece C, the symbol "B" was entered if slight microvoids were observed, and the symbol "C" was entered if obvious abnormalities in appearance such as swelling or peeling were observed. Note that test piece C in which abnormalities were observed in appearance after 24 hours of humidification was not evaluated after 72 hours of humidification. When no evaluation was performed, the symbol "-" was entered in the "Soldering Heat Resistance" column of Tables 1 and 2.

[0269] (Electrical Conductivity) Test piece D shown in FIG. 4 was used to evaluate electrical conductivity. The electrical conductivity was evaluated based on the electrical resistance between the metal plate 5 and the circuit pattern 62 of test piece D. In this example, the electrical resistance of test piece D was measured in the initial state, after the high-temperature, high-humidity test, after 24 hours of humidification, and after 72 hours of humidification. Note that test piece D in the initial state refers to test piece D immediately after being obtained by the method described above. Furthermore, test piece D after the high-temperature, high-humidity test, test piece D after 24 hours of humidification, and test piece D after 72 hours of humidification refer to test piece D after the high-temperature, high-humidity test, 24 hours of humidification, or 72 hours of humidification, respectively, by the method described above.

[0270] In the "Conductivity" column of Tables 1 and 2, the symbol "A" was entered when the electrical resistance between the metal plate 5 and the circuit pattern 62 was 0.3 Ω or less, the symbol "B" was entered when it was more than 0.3 Ω and less than 1.0 Ω, and the symbol "C" was entered when it exceeded 1.0 Ω. Note that when the cured material layer 1 did not contain the conductive inorganic filler (D), the metal plate 5 and the circuit pattern 62 were electrically insulated by the cured material layer 1, and therefore, electrical resistance measurement was not performed for such test piece D. When electrical resistance measurement was not performed, the symbol "-" was entered in the "Conductivity" column of Tables 1 and 2.

[0271] (Flame Retardancy) Test piece A shown in Figure 1 was used to evaluate flame retardancy according to a method in accordance with UL94. In the "Flame Retardancy" column of Tables 1 and 2, if the flame retardancy based on UL94 was judged to be VTM-0, it was recorded as "Good," and if it was judged to be VTM-1 or less, it was recorded as "Poor." Note that if the cured product did not contain a flame retardant, flame retardancy was not evaluated. If flame retardancy was not evaluated, the symbol "-" was recorded in the "Flame Retardancy" column of Tables 1 and 2.

[0272] (Storage Stability) Adhesive compositions were used to evaluate storage stability. In evaluating storage stability, first, the initial viscosity of the adhesive composition was measured. Then, the adhesive composition was sealed in a glass bottle and stored in an environment of 5°C. After two months had passed since the start of storage, the viscosity of the adhesive composition removed from the glass bottle was measured. Then, storage stability was evaluated based on the ratio of the viscosity after storage to the initial viscosity. In the "Storage Stability" column of Tables 1 and 2, the symbol "A" was entered when the viscosity after storage was two times or less than the initial viscosity, the symbol "B" was entered when the viscosity was more than two times but less than 10 times the initial viscosity, and the symbol "C" was entered when the viscosity exceeded 10 times.

[0273]

[0274]

[0275] As shown in Table 1, the adhesive compositions of Examples 1 to 10 contained a polyester resin (A), an epoxy compound (B), and a cyclic carbodiimide (C) in the specified ratios. Therefore, adhesive layers formed from these adhesive compositions exhibited excellent adhesion, high peel strength, and suppressed peeling of the adherend, even in moist conditions, such as after a high-temperature, high-humidity test, 24 hours of humidification, or 72 hours of humidification. Furthermore, when a metal plate and a flexible printed wiring board were bonded using an adhesive composition containing a conductive filler (D), electrical connection between the metal plate and the circuit pattern was maintained even after a high-temperature, high-humidity test, 24 hours of humidification, or 72 hours of humidification.

[0276] In contrast, the adhesive composition of Comparative Example 1 shown in Table 2 does not contain a cyclic carbodiimide (C). As a result, the cured product made from the adhesive composition of Comparative Example 1 showed a significant deterioration in solder heat resistance after 24 hours of humidification.

[0277] The adhesive composition of Comparative Example 2 had an excessively high content of cyclic carbodiimide (C), and therefore exhibited lower solder heat resistance in an absolutely dry state than the adhesive compositions of Examples 1 to 10. Furthermore, the cured product of the adhesive composition of Comparative Example 2 exhibited significantly worse solder heat resistance after 72 hours of humidification. Furthermore, the adhesive composition of Comparative Example 2 also exhibited inferior storage stability compared to the adhesive compositions of Examples 1 to 10.

[0278] In the adhesive composition of Comparative Example 3, polyamide was used instead of polyester resin (A). Therefore, the effect of cyclic carbodiimide (C) was small, and peel adhesive strength decreased after high-temperature, high-humidity testing. Furthermore, the cured product made from the adhesive composition of Comparative Example 3 showed a significant deterioration in solder heat resistance after 72 hours of humidification.

[0279] In the adhesive composition of Comparative Example 4, an acyclic carbodiimide was used instead of the cyclic carbodiimide (C). Therefore, the same effect as that of the cyclic carbodiimide (C) could not be obtained, and the solder heat resistance in an absolutely dry state was lower than that of the adhesive compositions of Examples 1 to 10. Furthermore, the solder heat resistance of the cured product of the adhesive composition of Comparative Example 4 was significantly deteriorated after 24 hours of humidification. This is thought to be because, when the acyclic carbodiimide reacts with a carboxy group of the polyester resin (A), the acyclic carbodiimide is cleaved into two at the carbodiimide group, making it difficult for isocyanate groups to remain in the semi-cured or cured product of the adhesive composition.

[0280] The above has explained aspects of the adhesive composition, bonding film, laminate with an adhesive layer, electromagnetic wave shielding material, and laminate based on examples, but the specific aspects of the adhesive composition etc. according to the present invention are not limited to those in the examples, and the configuration can be changed as appropriate within the scope that does not impair the spirit of the present invention.

Claims

1. An adhesive composition comprising a polyester resin (A) containing an ester bond for bonding repeating units to each other and one or two functional groups selected from the group consisting of a carboxy group and a carboxylic anhydride structure, an epoxy compound (B) in an amount of 1 to 50 parts by mass based on 100 parts by mass of the polyester resin (A), and a cyclic carbodiimide (C) in an amount of 0.1 to 20 parts by mass based on 100 parts by mass of the polyester resin (A).

2. The adhesive composition according to claim 1, wherein the polyester resin (A) is a polyester polyamide and / or a polyester polyurethane.

3. The adhesive composition according to claim 1, wherein the water absorption rate when the cured product of the adhesive composition is immersed in water at 23°C for 24 hours is 3% or less.

4. The adhesive composition according to claim 1, wherein the acid value of the polyester resin (A) is 0.1 mgKOH / g or more and 5 mgKOH / g or less.

5. The adhesive composition according to claim 1, wherein the weight average molecular weight of the polyester resin (A) is 5,000 or more and 150,000 or less.

6. The adhesive composition according to claim 1, further comprising an inorganic filler (D).

7. The adhesive composition according to claim 6, wherein the content of the inorganic filler (D) is 10 to 350 parts by mass based on a total of 100 parts by mass of the contents of the polyester resin (A), the epoxy compound (B), and the cyclic carbodiimide (C).

8. The adhesive composition according to claim 6, wherein the inorganic filler (D) has conductivity.

9. A bonding film having an adhesive layer and a release film provided on one or both surfaces of the adhesive layer and configured to be peelable from the adhesive layer, wherein the adhesive layer is composed of the adhesive composition according to any one of claims 1 to 8 or a semi-cured product obtained by partially curing the adhesive composition.

10. A laminate with an adhesive layer having an adhesive layer and a base material layer adhered to at least one surface of the adhesive layer, wherein the adhesive layer is composed of the adhesive composition according to any one of claims 1 to 8 or a semi-cured product obtained by partially curing the adhesive composition.

11. An electromagnetic shielding material having a conductive adhesive layer, wherein the conductive adhesive layer is composed of the adhesive composition according to claim 8 or a semi-cured product obtained by partially curing the adhesive composition.

12. The electromagnetic shielding material according to claim 11, wherein the electromagnetic shielding material has a protective layer provided on the conductive adhesive layer.

13. A laminate including a cured product layer made of a cured product of the adhesive composition according to any one of claims 1 to 8.

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