JP5976112B2 - Curable conductive adhesive composition, electromagnetic wave shielding film, conductive adhesive film, adhesion method and circuit board - Google Patents

Description

The present invention relates to a curable conductive adhesive composition, an electromagnetic wave shielding film, a conductive adhesive film, an adhesion method, and a circuit board.

In the flexible substrate, a conductive adhesive is often used (Patent Documents 1 to 3).
These conductive adhesives are used to bond the electromagnetic wave shielding film to the conductive circuit of the flexible substrate, and to impart electromagnetic wave shielding performance to the metallic reinforcing plate, the reinforcing plate and the conductive circuit of the flexible substrate. It can be used for adhesion when connecting.

However, from the viewpoint of increasing the required physical properties in recent years, it has been required to improve the physical properties of the conductive adhesive composition. For example, when a conductor circuit is formed by high-density mounting, the flexible substrate may be uneven. In the case where an electromagnetic wave shielding film or a reinforcing plate is bonded on such a concavo-convex shape, it is important that the resin flows appropriately in the hot press process for bonding.

Conventional conductive adhesives used when connecting electromagnetic shielding films and reinforcing plates used a resin with good fluidity to ensure fluidity, making it difficult to control the resin flow. . On the other hand, when a high molecular weight resin is used to control the resin flow, the embeddability in the opening for the purpose of connecting to the ground circuit portion of the flexible substrate or the step of the rigid flex is impaired. It was.

Patent Document 4 describes a curable polyurethane polyurea adhesive composition containing a polyurethane polyurea resin, two types of epoxy resins, and a conductive filler. However, in such an adhesive composition, there is no description relating to use for adhesion between the reinforcing plate and the circuit board, and further, the above-described problems cannot be solved sufficiently.

Furthermore, Patent Document 5 describes that an adhesive composition containing a polyurethane polyurea resin and an epoxy resin is used for bonding a reinforcing plate and a flexible substrate. However, there is no description about making the reinforcing plate have electromagnetic wave shielding performance by making the adhesive composition conductive.

JP 2007-189091 A JP 2009-218443 A JP 2005-317946 A JP 2010-143981 A International Publication No. 2007/032463

In view of the above, an object of the present invention is to provide a curable conductive adhesive composition that can control the resin flow and ensure the embedding property.

The present invention relates to a polyurethane resin (A) having at least one functional group selected from the group consisting of a carboxyl group and a hydroxyl group, a carbon-carbon unsaturated bond and an alkoxysilyl group, and two or more epoxy groups per molecule. A curable conductive material comprising an epoxy resin (B) having at least one additive (C) selected from the group consisting of a crosslinking agent, a polymerization initiator and a tin-based metal catalyst, and a conductive filler (D) It is an adhesive composition.

Further, the present invention is selected from the group consisting of a polyurethane resin (A ′) having a carboxyl group, an epoxy resin (B) having two or more epoxy groups per molecule, an isocyanate compound, a blocked isocyanate compound and an oxazoline compound. The curable conductive adhesive composition is characterized by containing at least one additive (C ′) and a conductive filler (D).

It is preferable that at least one of the polyurethane resin (A) and the polyurethane resin (A ′) has an acid value of 3 to 100 mgKOH / g.
At least one of the polyurethane resin (A) and the polyurethane resin (A ′) preferably has a weight average molecular weight of 1,000 to 1,000,000.

The epoxy resin (B) is preferably composed of at least one of an epoxy resin (B1) having an epoxy equivalent of 800 to 10,000 and an epoxy resin (B2) having an epoxy equivalent of 90 to 300.

In this case, it is preferable that the epoxy resin (B1) is a bisphenol type epoxy resin and the epoxy resin (B2) is a novolac type epoxy resin.

The conductive filler (D) is preferably at least one selected from the group consisting of silver powder, silver-coated copper powder and copper powder.
The conductive filler (D) preferably has an average particle diameter of 3 to 50 μm.

This invention is also an electromagnetic wave shielding film characterized by laminating | stacking the conductive adhesive layer and protective layer which used the curable conductive adhesive composition mentioned above.
This invention is also an electromagnetic wave shielding film characterized by laminating a conductive adhesive layer, a metal layer, and a protective layer using the above-described curable conductive adhesive composition.

In the electromagnetic wave shielding film, the thickness of the conductive adhesive layer is preferably 3 to 30 μm.
The present invention also has a conductive adhesive layer formed by the electromagnetic wave shielding film described above, and the conductive adhesive layer is also connected to a ground circuit of a printed circuit board. .

This invention is also a conductive adhesive film characterized by having an adhesive layer obtained by using the curable conductive adhesive composition described above.
The conductive adhesive film preferably has a thickness of 15 to 100 μm.

The present invention includes a step (1) of temporarily bonding the above-described conductive adhesive film on a substrate to be bonded (X) which is a reinforcing plate or a flexible substrate, and a conductive adhesive film obtained by the step (1). It is also an adhesion method comprising a step (2) of superimposing a substrate to be adhered (Y), which is a flexible substrate or a reinforcing plate, on the adhesive substrate (X) and hot pressing.

The present invention is a circuit board having at least a portion where a flexible substrate, a conductive adhesive layer, and a conductive reinforcing plate are laminated in this order, and the conductive adhesive layer is formed by the conductive adhesive film described above. It is also a circuit board characterized by being made.
The circuit board may have a surface other than the reinforcing plate on the surface of the flexible substrate covered with an electromagnetic wave shielding film.

The curable conductive adhesive composition of the present invention has excellent performance by flowing appropriately during bonding. Thereby, excellent adhesion can be performed even on a substrate having an uneven shape. In addition, there is an advantage that the embedding property can be secured.

It is an example of the circuit board obtained by using the conductive adhesive of this invention as an electromagnetic wave shield layer. It is an example of the circuit board obtained by using the conductive adhesive of this invention as an electromagnetic wave shield layer. It is an example of the circuit board obtained by using the conductive adhesive of this invention as a conductive adhesive film. It is a schematic diagram which shows the 90 degree peel strength measuring method of an Example. It is an example of the connection resistance measurement test piece of an Example. It is a schematic diagram which shows the 180 degree peel strength measuring method of an Example. It is a schematic diagram which shows the mode of the resin flow of an Example.

The present invention is described in detail below.
<First embodiment>
The curable conductive adhesive composition of the present invention comprises a polyurethane resin (A) having at least one functional group selected from the group consisting of a carboxyl group and a hydroxyl group, a carbon-carbon unsaturated bond and an alkoxysilyl group, An epoxy resin (B) having two or more epoxy groups in the molecule, at least one additive (C) selected from the group consisting of a crosslinking agent, a polymerization initiator and a tin-based metal catalyst, and a conductive filler (D) It contains. As a result, a curing reaction by a plurality of types of curing reactions is performed, so that the resin flow can be controlled, so that it has an appropriate flow performance that can cope with adhesion to a surface having an uneven shape. Is.

(Polyurethane resin (A))
In the present specification, “polyurethane” means a general term for polyurethane and polyurethane-urea. The “polyurethane” may be a product obtained by reacting an amine component as necessary.

The polyurethane resin (A) used in the present embodiment has a carboxyl group and at least one functional group selected from the group consisting of a hydroxyl group, a carbon-carbon unsaturated bond and an alkoxysilyl group as a reactive functional group. . By having such a reactive functional group, the resin flow can be controlled by the effect that it becomes possible to control the heat softening temperature in the hot press step described later.

At least one functional group selected from the group consisting of a hydroxyl group, a carbon-carbon unsaturated bond, and an alkoxysilyl group is present in the main chain even if present in the side chain of the polyurethane resin. Alternatively, it may be present as a terminal group.

The polyurethane resin (A) used in the present invention comprises a polyol compound (1) containing a carboxyl group, a polyol (2), a short-chain diol compound (3) if necessary, and a polyamine compound (4) if necessary. And a polyisocyanate compound (5).
More preferably, the polyurethane resin (A) is a polyol compound (1) containing a carboxyl group, a polyol (2), a short-chain diol compound (3) and / or a diamine compound (4) used as necessary. The active hydrogen-containing group (excluding the carboxyl group of the polyol compound (1)) and the isocyanate group (5) are reacted at an equivalent ratio of 0.5 to 1.5.

As a method for introducing a reactive functional group other than a carboxyl group into the polyurethane resin (A) used in the present invention, in the above components (1) to (5), a single monomer having a reactive functional group to be introduced A method of carrying out a reaction using a part or all of a body; an attempt to introduce a side chain or a terminal reactive group in a polyurethane resin obtained by using the components (1) to (5) described above; And a method of reacting with a compound having a functional group.

Specific examples of the polyol compound (1) containing a carboxyl group include dimethylol alkanoic acid such as dimethylolpropanoic acid and dimethylolbutanoic acid; alkylene oxide low-mole adduct of dimethylolalkanoic acid (number by terminal functional group quantification). Ε-caprolactone low molar adduct of dimethylol alkanoic acid (number average molecular weight less than 500 by terminal functional group determination); half esters derived from dimethylol alkanoic acid anhydride and glycerin; Examples thereof include compounds obtained by free radical reaction of a hydroxyl group of dimethylolalkanoic acid, a monomer having an unsaturated bond, and a monomer having a carboxyl group and an unsaturated bond. Of these, dimethylolpropanoic acid and dimethylolalkanoic acid such as dimethylolbutanoic acid are preferred from the viewpoints of availability, ease of adjustment of acid value, and the like. The content of the polyol compound (1) in the polyurethane resin (A) is such that the resulting polyurethane resin (A) is cross-linked with the epoxy resin (B), thereby improving heat resistance and durability, and flexibility and adhesion. It is set from the viewpoint of both. More specifically, the content of the polyol compound (1) in the reaction component is preferably such that the acid value of the resulting polyurethane resin (A) is 3 to 100 mg KOH / g, and 3 to 50 mg KOH / g. More preferably, the amount is g.

The polyol (2) is a component having two or more hydroxyl groups, and those having a number average molecular weight of 500 to 3000 can be preferably used. In addition, the said polyol (2) points out only what does not correspond to the said polyol compound (1).

The polyol (2) is not particularly limited, and a conventionally known polyol used for urethane synthesis can be used. Specific examples of the polyol (2) include polyester polyol, polyether polyol, polycarbonate polyol, and other polyols.

Polyester polyols include aliphatic dicarboxylic acids (eg succinic acid, adipic acid, sebacic acid, glutaric acid, azelaic acid etc.) and / or aromatic dicarboxylic acids (eg isophthalic acid, terephthalic acid etc.), low Molecular weight glycol (for example, ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, etc. ) And those obtained by condensation polymerization.

Specific examples of such polyester polyols include polyethylene adipate diol, polybutylene adipate diol, polyhexamethylene adipate diol, polyneopentyl adipate diol, polyethylene / butylene adipate diol, polyneopentyl / hexyl adipate diol, poly-3- Examples thereof include methylpentane adipate diol, polybutylene isophthalate diol, polycaprolactone diol, and poly-3-methylvalerolactone diol.

Specific examples of the polyether polyol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and random / block copolymers thereof. Specific examples of the polycarbonate polyol include polytetramethylene carbonate diol, polypentamethylene carbonate diol, polyneopentyl carbonate diol, polyhexamethylene carbonate diol, poly (1,4-cyclohexanedimethylene carbonate) diol, and random / Examples thereof include a block copolymer.

Specific examples of other polyols include dimer diol, polybutadiene polyol and its hydrogenated product, polyisoprene polyol and its hydrogenated product, acrylic polyol, epoxy polyol, polyether ester polyol, siloxane-modified polyol, α, ω-polymethyl Examples thereof include methacrylate diol and α, ω-polybutyl methacrylate diol.

The number average molecular weight (Mn, based on terminal functional group determination) of the polyol (2) is not particularly limited, but is preferably 500 to 3,000. If the number average molecular weight (Mn) of the polyol (2) is more than 3,000, the cohesive force of urethane bonds is hardly expressed and the mechanical properties tend to be lowered. In addition, a crystalline polyol having a number average molecular weight of more than 3,000 may cause a whitening phenomenon when formed into a film. In addition, a polyol (2) can be used individually by 1 type or in combination of 2 or more types.

In addition, as a reaction component for obtaining a polyurethane resin (A), it is also preferable to use a short chain diol component (3) and / or a diamine component (4) as needed. This makes it easy to control the hardness and viscosity of the polyurethane resin (A). Specific examples of the short-chain diol component (3) include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,6-hexamethylene glycol, neopentyl glycol, and the like. Aliphatic glycol and its alkylene oxide low molar adduct (number average molecular weight less than 500 by terminal functional group determination); 1,4-bishydroxymethylcyclohexane, 2-methyl-1,1-cyclohexanedimethanol and other alicyclic glycols And its alkylene oxide low molar adduct (number average molecular weight less than 500, same as above); aromatic glycol such as xylylene glycol and its alkylene oxide low mole adduct (number average molecular weight less than 500, same as above); bisphenol A, thiobisphenol, Sulfonbispheno Bisphenols and alkylene oxide low molar adducts such as Le (number average molecular weight of less than 500, supra); and alkyl dialkanolamine such as alkyl diethanolamine C1~C18 can be mentioned.

Specific examples of the diamine compound (4) include aliphatic diamine compounds such as methylene diamine, ethylene diamine, trimethylene diamine, hexamethylene diamine and octamethylene diamine; phenylene diamine and 3,3′-dichloro. Aromatic diamine compounds such as -4,4'-diaminodiphenylmethane, 4,4'-methylenebis (phenylamine), 4,4'-diaminodiphenyl ether, 4,4'-diaminodiphenylsulfone; cyclopentyldiamine, cyclohexyldiamine, 4 And alicyclic diamine compounds such as 1,4′-diaminodicyclohexylmethane, 1,4-diaminocyclohexane and isophoronediamine. Furthermore, hydrazines such as hydrazine, carbodihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, phthalic acid dihydrazide can be used as the diamine compound (4). Examples of long-chain ones include long-chain alkylene diamines, polyoxyalkylene diamines, terminal amine polyamides, and siloxane-modified polyamines. These diamine compounds (4) can be used singly or in combination of two or more.

As the polyisocyanate compound (5), a conventionally known polyisocyanate used in the production of polyurethane can be used. Specific examples of the polyisocyanate (5) include toluene-2,4-diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene. Diisocyanate, 4-butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4′-methylenebis (phenylene isocyanate) (MDI), durylene diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), 1, Aromatic diisocyanates such as 5-naphthalene diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, 4,4′-diisocyanate dibenzyl; methylene diisocyanate Aliphatic diisocyanates such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,10-decamethylene diisocyanate; 1,4-cyclohexylene diisocyanate, 4,4-methylenebis (cyclohexyl isocyanate), 1 , 5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, hydrogenated MDI, hydrogenated XDI, and other alicyclic diisocyanates; obtained by reacting these diisocyanates with low molecular weight polyols or polyamines so that the ends are isocyanates. Examples include polyurethane prepolymers. From the viewpoint of obtaining a polymer composition having excellent weather resistance, aliphatic diisocyanates and alicyclic diisocyanates are preferred.

Further, the polyisocyanate compound (5) may have a blocking group at the terminal portion. That is, it may be formed by forming an isocyanate terminal by reacting with an excess of an isocyanate group, and blocking the terminal by reacting the isocyanate terminal with a monofunctional group compound.

Introducing these functional groups using at least one of a compound that introduces a hydroxyl group, a compound that introduces an unsaturated bond, and a compound that introduces an alkoxysilyl group after or during the reaction of each component described above. Can do.

As the compound for introducing a hydroxyl group, mono- and diamines having a hydroxyl group can be used, and the monoamine can introduce a hydroxyl group into the polyurethane resin chain using a diamine as a chain extender at the end of the polyurethane resin. Can do. A polyhydric alcohol containing two or more hydroxyl groups in the molecule can also introduce a hydroxyl group at the end of the polyurethane resin by reacting an excess amount with the prepolymer.

Examples of the monoamine having a hydroxyl group include monoethanolamine, diethanolamine, N-methylethanolamine, N-ethylethanolamine, and N-hydroxyethylpiperazine. Examples of the diamine having a hydroxyl group include N-aminoethyl. Examples thereof include ethanolamine and N-aminoethylisopropanolamine. Examples of the polyhydric alcohol include ethylene glycol, 1,3-propanediol, propylene glycol, 1,4-butanediol, 1,3-butanediol, N-methyldiethanolamine, triethanolamine, glycerin, and trimethylolpropane. be able to.

When a hydroxyl group is introduced into the polyurethane resin, the hydroxyl value is preferably 3 to 300 mgKOH / g.

  As the compound for introducing an unsaturated bond, monools and diols having an unsaturated bond can be used. The monool is used at the end of the polyurethane resin, and the diol is used as a chain extender. Unsaturated bonds can be introduced. Specific examples of the compound that introduces an unsaturated bond include monoallyl having an unsaturated bond, allyl alcohol, hydroxyethyl acrylate (HEA), hydroxyethyl methacrylate (HEMA) (hereinafter, acrylic and methacryl are combined ( Meth) acrylic), and these ethylene oxide, propylene oxide, or ε-caprolactone adducts, hydroxybutyl (meth) acrylate, 1,4-cyclohexanedimethanol mono (meth) acrylate, glycerin di (meth) acrylate, Examples thereof include trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, and the diol includes glycerin monoallyl ether, glycerin mono (meth) acrylate, poly Taj diol, such as dimer diol can be mentioned.

In addition, after synthesizing a polyurethane resin containing a carboxyl group, glycidyl (meth) acrylate is added thereto, and the carboxyl group of the polyurethane resin and the epoxy group of glycidyl (meth) acrylate are reacted to form a side chain of the polyurethane resin. It is also possible to introduce an unsaturated bond into.

When an unsaturated bond is introduced into the polyurethane resin, the unsaturated bond equivalent is preferably 300 to 10,000 g / eq.

Mono- and diamines having an alkoxysilyl group, or thiols can be used as the compound for introducing an alkoxysilyl group. The monoamine and thiol are used at the end of the polyurethane resin, and the diamine is used as a chain extender. Alkoxysilyl groups can be introduced into the resin chain. Specific examples of the compound that introduces an alkoxysilyl group include monoamino amines having an alkoxysilyl group, such as 3-aminopropyltrimethoxysilane and 3-aminopropyltriethoxysilane. N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltriethoxysilane Examples of thiols having an alkoxysilyl group include 3-mercaptopropyltrimethoxysilane and 3-mercaptopropylmethyldimethoxysilane.

When introducing an alkoxysilyl group into a polyurethane resin, the amount introduced is preferably 0.01 to 10% by weight in terms of the amount of silicon atoms in the resin.

An active hydrogen group such as a polyol compound (1), a polyol (2), a short-chain diol compound (3), if necessary, a polyamine compound (4), etc. It is preferable that the equivalent ratio of the isocyanate group of the polyisocyanate compound (5) to (1) does not include a carboxyl group) is 0.5 to 1.5. Within the above range, it is preferable in that a polyurethane resin (A) having high heat resistance and high mechanical strength can be obtained.

(Method for producing polyurethane resin (A))
The polyurethane resin (A) can be produced by a conventionally known polyurethane production method. Specifically, first, in the presence or absence of an organic solvent containing no active hydrogen in the molecule, a polyol compound (1) containing a carboxyl group, a polyol (2), and a chain extender as necessary. A reaction comprising: a short-chain diol compound (3) used as necessary; a polyamine compound (4) used as needed; a functional group-introducing component serving as a reaction point used as needed; and a polyisocyanate (5). The components are reacted to obtain a reactant (eg, a prepolymer).
In general, the reaction component may be a blended composition in which a prepolymer having a terminal isocyanate group is formed. Moreover, what is necessary is just to make it react until it becomes theoretical isocyanate% by 20-150 degreeC normally by the one shot method or a multistage method, Preferably it is 60-110 degreeC.

The obtained reaction product (prepolymer) may be chain-extended so as to have a desired molecular weight by reacting the diamine compound (4), if necessary, and at the same time, a compound having the above-described functional group is used. Then, a functional group serving as a reaction point may be introduced. Further, the total active hydrogen-containing group of the polyol compound (1), polyol (2), short chain diol compound (3), and polyamine compound (4) containing a carboxyl group (excluding the carboxyl group of the compound (1)). And the isocyanate group (2) of the polyisocyanate compound (5) are preferably reacted at an equivalent ratio of 0.5 to 1.5.

The polyurethane resin (A) obtained as described above preferably has a weight average molecular weight (Mw) of 1,000 to 1,000,000, and more preferably 2,000 to 1,000,000. Polyurethane is preferred because the properties such as flexibility, adhesion, heat resistance, and coating performance are more effectively exhibited.
The number average molecular weight (Mn) of the polyurethane resin (A) obtained as described above is preferably 400 to 450,000, and more preferably 850 to 450,000, which is the flexibility and adhesion of polyurethane. It is preferable because properties such as heat resistance and coating performance are more effectively exhibited.
In the present specification, “weight average molecular weight (Mw)” and “number average molecular weight (Mn)” mean values in terms of polystyrene measured by gel permeation chromatography (GPC) unless otherwise specified. .

In the polyurethane resin (A), the higher the acid value, the more the crosslinking points and the higher the heat resistance. However, the polyurethane resin (A) having an acid value that is too high may be too hard to reduce flexibility, and the carboxyl group may not be reacted with an epoxy group or the like, resulting in reduced durability. For this reason, it is preferable that the acid value of a polyurethane resin (A) is 3-100 mgKOH / g, and it is further more preferable that it is 3-50 mgKOH / g.

In the present invention, a catalyst can be used as necessary in the urethane synthesis. For example, salts of metals and organic and inorganic acids such as dibutyltin laurate, dioctyltin laurate, stannous octoate, zinc octylate, tetra-n-butyl titanate, and organic amine derivatives such as organometallic derivatives, triethylamine, diaza Bicycloundecene catalysts and the like can be mentioned.

The polyurethane resin (A) may be synthesized without using a solvent or may be synthesized with an organic solvent. As the organic solvent, an organic solvent inert to the isocyanate group or an organic solvent less active than the reaction component with respect to the isocyanate group can be used. Specific examples of organic solvents include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; toluene, xylene, swazole (trade name, manufactured by Cosmo Oil Co., Ltd.), Solvesso (trade name, manufactured by Exxon Chemical Co., Ltd.) Aromatic hydrocarbon solvents such as n-hexane; Alcohol solvents such as methanol, ethanol and isopropyl alcohol; Ether solvents such as dioxane and tetrahydrofuran; Ethyl acetate, butyl acetate and isobutyl acetate Ester solvents such as ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate, etc. Ether-based solvents; dimethylformamide, amide solvents such as dimethylacetamide; lactams solvents such as N- methyl-2-pyrrolidone and the like.

In the urethane synthesis, when an isocyanate group remains at the end of the polymer, it is also preferable to perform a termination reaction of the isocyanate group. The termination reaction of the isocyanate group can be performed using a compound having reactivity with the isocyanate group. As such a compound, a monofunctional compound such as monoalcohol or monoamine; a compound having two kinds of functional groups having different reactivity with respect to isocyanate can be used. Specific examples of such compounds include monoalcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, tert-butyl alcohol; monoethylamine, n-propylamine, diethylamine And monoamines such as di-n-propylamine and di-n-butylamine; alkanolamines such as monoethanolamine and diethanolamine. Of these, alkanolamine is preferable because of easy control of the reaction. In addition, it is also possible to introduce a functional group serving as a reaction point into the end of the polyurethane molecule by terminating the isocyanate group using a component containing the functional group serving as a reaction point as described above.

The polyurethane resin (A) having a hydroxyl group in addition to the carboxyl group can obtain the effects of the present invention by performing a crosslinking reaction with an isocyanate crosslinking agent, a blocked isocyanate crosslinking agent, or the like.

As the isocyanate crosslinking agent, a burette type, an adduct type, a nurate type, a prepolymer type, and a block body thereof can be used. The mass ratio of the hydroxyl group in the polyurethane resin (A) to the isocyanate crosslinking agent, the blocked isocyanate crosslinking agent, etc. is in the range of 0.5 to 200 parts by mass with respect to 100 parts by mass of the resin component of the polyurethane resin. Is preferred.

In addition to the carboxyl group, the polyurethane resin (A) having an unsaturated bond can undergo a crosslinking reaction between the unsaturated bonds by ultraviolet rays or electron beams in the presence or absence of various photopolymerization initiators. In addition, a crosslinking reaction can be performed by a thermal reaction in the presence of a known polymerization initiator such as a peroxide or an azo compound.

Further, in addition to the carboxyl group, the polyurethane resin (A) having an unsaturated bond can undergo a crosslinking reaction between the unsaturated bonds by heat treatment with peroxide as an initiator or with oxygen in the presence of a catalyst. .

In addition to the carboxyl group, the polyurethane resin (A) having an alkoxysilyl group is hydrolyzed in the presence or absence of a catalyst, and silanol groups are further condensed to form a siloxane bond. Furthermore, it can also be made to react with such a crosslinking agent by using together an isocyanate crosslinking agent, a blocked isocyanate crosslinking agent, etc. As a polyisocyanate compound which can be used, what was illustrated as a polyisocyanate compound mentioned above can be used.

These reactions require a heat treatment of 130 to 180 ° C. and 15 to 90 minutes for reactions with epoxy groups and carboxyl groups, while proceeding at a lower temperature, such as UV or electron beam crosslinking, at room temperature. The crosslinking reaction also proceeds by treatment at room temperature to 120 ° C., and an adhesive layer excellent in processability can be obtained while maintaining adhesion and flexibility.

(Epoxy resin (B))
The curable conductive adhesive composition of the present invention further contains an epoxy resin (B).
It does not specifically limit as an epoxy resin (B) to be used, The arbitrary well-known thing which has a 2 or more epoxy group in 1 molecule can be used.

More specifically, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol type epoxy resin such as bisphenol S type epoxy resin, spiro ring type epoxy resin, naphthalene type epoxy resin, biphenyl type epoxy resin, terpene type epoxy resin , Glycidyl ether type epoxy resins such as tris (glycidyloxyphenyl) methane, tetrakis (glycidyloxyphenyl) ethane, glycidylamine type epoxy resins such as tetraglycidyldiaminodiphenylmethane, tetrabromobisphenol A type epoxy resins, cresol novolac type epoxy resins, Novolak type epoxy such as phenol novolak type epoxy resin, α-naphthol novolak type epoxy resin, brominated phenol novolak type epoxy resin The sheet resin can be used.

More preferably, it is preferable to use a mixture of two types of epoxy resins (B). This is preferable in that balanced physical properties can be obtained. When mixing two types of epoxy resins (B), the same type of epoxy resins (B) having different epoxy equivalents may be mixed and used, or different types of epoxy resins (B) may be used in combination. May be.

More preferably, the two epoxy resins (B) are those having an epoxy equivalent of 800 to 10,000 (epoxy resin (B1)) and those having an epoxy equivalent of 90 to 300 (epoxy resin (B2)). It is preferable to use it in combination. In this case, the epoxy resin (B1) and the epoxy resin (B2) may be the same type or may have different chemical structures.

As said epoxy resin (B1), it is preferable to use what has an epoxy equivalent of 800-10000. This is preferable in that the adhesion with a reinforcing plate or an adherend (Ni-SUS, SUS, gold-plated electrode, polyimide resin, etc.) is further improved. The lower limit of the epoxy equivalent is more preferably 1000, and still more preferably 1500. The upper limit of the epoxy equivalent is more preferably 5000, and still more preferably 3000. Moreover, as said epoxy resin (B1), it is preferable to use a solid thing at normal temperature. Being solid at room temperature means a solid state having no fluidity in a solvent-free state at 25 ° C.

As commercially available epoxy resins that can be used as the epoxy resin (B1), EPICLON 4050, 7050, HM-091, HM-101 (trade name, manufactured by DIC Corporation), jER1003F, 1004, 1004AF, 1004FS, 1005F, 1006FS, 1007, 1007FS, 1009, 1009F, 1010, 1055, 1256, 4250, 4275, 4004P, 4005P, 4007P, 4010P (trade names, manufactured by Mitsubishi Chemical Corporation) and the like.

The epoxy resin (B2) particularly preferably has an epoxy equivalent of 90 to 300.
As a result, the effect of increasing the heat resistance of the resin is obtained. The lower limit of the epoxy equivalent is more preferably 150, and even more preferably 170. The upper limit of the epoxy equivalent is more preferably 250, and still more preferably 230. Moreover, as said epoxy resin (B2), it is preferable to use a solid thing at normal temperature.

The epoxy resin (B2) is more preferably a novolak type epoxy resin. Although novolac epoxy resin has high epoxy resin density, it has good miscibility with other epoxy resins and has little reactivity difference between epoxy groups. High crosslink density can be achieved uniformly.
The novolak type epoxy resin is not particularly limited, and examples thereof include a cresol novolak type epoxy resin, a phenol novolak type epoxy resin, an α-naphthol novolak type epoxy resin, and a brominated phenol novolak type epoxy resin.

Commercially available epoxy resins that can be used as the epoxy resin (B2) as described above include EPICLON N-660, N-665, N-670, N-673, N-680, N-695, N-655. -EXP-S, N-662-EXP-S, N-665-EXP, N-665-EXP-S, N-672-EXP, N-670-EXP-S, N-685-EXP, N-673 -80M, N-680-75M, N-690-75M, N-740, N-770, N-775, N-740-80M, N-770-70M, N-865, N-865-80M Name, manufactured by DIC Corporation), jER152, 154, 157S70 (trade name, manufactured by Mitsubishi Chemical Corporation), YDPN-638, YDCN-700, YDCN-700-2, YDCN-70 -3, YDCN-700-5, YDCN-700-7, YDCN-700-10, YDCN-704, YDCN-700-A (trade name, manufactured by Nippon Steel Chemical Co., Ltd.), and the like can be given.

Moreover, when using a novolak-type epoxy resin as said epoxy resin (B2), the said epoxy resin (B1) can use the bisphenol-type epoxy resin which is solid at normal temperature. This is because sufficient adhesion can be obtained by using the novolac type epoxy resin (B2) and the bisphenol type epoxy resin (B1) in combination.

The curable conductive adhesive composition of the present embodiment preferably contains the epoxy resin (B1) and the epoxy resin (B2) in a weight ratio of 85:15 to 99: 1. Heat resistance that can withstand the reflow process at the time of component mounting, ensuring adhesion to reinforcing plates and adherends (Ni-SUS, SUS, gold-plated electrodes, polyimide resins, etc.) by using the above ratio Is preferable in terms of imparting. Further, in the above ratio, if the ratio of the epoxy resin (B1) is larger than 99: 1, it is not preferable in that it may not be able to endure the reflow process at the time of component mounting. When the ratio of B2) becomes large, it is not preferable in terms of a decrease in adhesion to an adherend (Ni-SUS, SUS, gold plating electrode, polyimide resin, etc.).

In addition, the epoxy equivalent in this specification is a value measured by potentiometric titration.

(Mixing ratio of polyurethane resin (A) and epoxy resin (B))
In the present embodiment, the mixing ratio of the polyurethane resin (A) and the epoxy resin (B) is preferably 70:30 to 30:70 in terms of the mass ratio of the polyurethane resin (A) and the epoxy resin (B). By setting it as the thing within the said range, it is preferable at the point that the flexible provision of a conductive adhesive film or an electromagnetic wave shield film, provision of film formability, and adjustment of heat resistance become easy.

(Additive (C))
The curable conductive adhesive composition of the present embodiment is a curable adhesive composition whose durability is further improved by adding an additive (C) (for example, a polymerization initiator, a crosslinking agent, a reaction catalyst, etc.). Can be obtained. In particular, it is preferable to use an additive (C) capable of reacting with a carboxyl group and a reactive functional group present in the molecule of the polyurethane resin (A) to cause the polyurethane resin (A) to undergo a crosslinking reaction. The additive (C) is intended to contribute to the reaction of the carboxyl group and the reactive functional group present in the molecule of the polyurethane resin (A), which simultaneously contributes to the reaction of the epoxy resin (B). It does not matter even if it does.

As the polymerization initiator, organic peroxide polymerization initiators such as cumene hydroperoxide and t-butylperoxy-2-ethylhexanoate, 2,2′-azobisisobutylnitrile, 2,2′-azobis (2 , 4-dimethylvaleronitrile) and the like azo polymerization initiators can be used. Commercially available organic peroxide polymerization initiators include Parkmill H and Parkmill O (manufactured by NOF Corporation), and commercially available azo polymerization initiators include ABN-R and ABN-V (manufactured by Nippon Finechem Co., Ltd.). ) And the like.

As a crosslinking agent, conventionally well-known crosslinking agents, such as an isocyanate compound, a block isocyanate compound, a carbodiimide compound, an oxazoline compound, a melamine, a metal complex type crosslinking agent, can be used. Among these crosslinking agents, an isocyanate compound, a blocked isocyanate compound, a carbodiimide compound, and an oxazoline compound are preferable. Examples of commercially available isocyanate compounds that can be used as a crosslinking agent include duranate (manufactured by Asahi Kasei Chemicals Corporation). Examples of commercially available carbodiimide compounds include carbodilite (Nisshinbo Chemical Co., Ltd.). Examples of commercially available oxazoline compounds include Epocross (manufactured by Nippon Shokubai Co., Ltd.).

As the reaction catalyst for the alkoxysilyl group, a tin-based metal catalyst such as monobutyl stannic acid or stannous octylate can be used. Examples of commercially available products include MBTO and stanoct (manufactured by API Corporation).

These additives (C) are effective in improving heat resistance and durability if they are in appropriate amounts. However, when there is too much usage-amount of an additive (C), a softness | flexibility, a fall of adhesiveness, etc. may be caused. For this reason, it is preferable that the usage-amount of an additive (C) shall be 0.1-200 mass parts or less with respect to 100 mass parts of resin components of a polyurethane resin (A), and shall be 0.2-100 mass parts. More preferably.

Among the crosslinking agents of the additive (C), an isocyanate compound (including a blocked isocyanate compound) is a crosslinking agent generally used for polyurethane resins, but in addition to a carboxyl group, a polyurethane resin having a hydroxyl group (A ) Reacts with the hydroxyl group to become a particularly effective crosslinking agent.

(Conductive filler (D))
The curable conductive adhesive composition of this embodiment contains a conductive filler (D). The conductive filler (D) is not particularly limited, and for example, a metal filler, a metal-coated resin filler, a carbon filler, and a mixture thereof can be used. Examples of the metal filler include copper powder, silver powder, nickel powder, silver-coated copper powder, gold-coated copper powder, silver-coated nickel powder, and gold-coated nickel powder. These metal powders are electrolyzed, atomized, and reduced. It can be produced by the method. Especially, it is preferable to use at least 1 electroconductive filler (D) selected from the group which consists of silver powder, silver coat copper powder, and copper powder especially.
In particular, in order to make it easy to obtain contact between the fillers, it is preferable that the conductive filler (D) has an average particle diameter of 3 to 50 μm. Examples of the shape of the conductive filler (D) include a spherical shape, a flake shape, a dendritic shape, and a fibrous shape.

In addition, the curable conductive adhesive composition includes a silane coupling agent, an antioxidant, a pigment, a dye, a tackifier resin, a plasticizer, an ultraviolet absorber, and an antifoaming agent as long as the solder reflow resistance is not deteriorated. , Leveling regulators, fillers, flame retardants and the like may be added.

(Anisotropic conductive adhesive layer, isotropic conductive adhesive layer)
The conductive adhesive layer of this embodiment may be an anisotropic conductive adhesive layer or an isotropic conductive adhesive layer, and can be any of these depending on the purpose. . For example, when using as an electromagnetic wave shielding film which does not have a metal layer explained in full detail below, and an electroconductive adhesive film for adhere | attaching with a reinforcement board, it is preferable to set it as an isotropic electroconductive adhesive layer. Moreover, in the case of the electromagnetic wave shielding film which has a metal layer, although an isotropic conductive adhesive layer may be sufficient, it is preferable that it is an anisotropic conductive adhesive layer.

These can be either an anisotropic conductive adhesive layer or an isotropic conductive adhesive layer depending on the blending amount of the conductive filler (D). In order to obtain an anisotropic conductive adhesive layer, the conductive filler is preferably 5% by weight or more and less than 40% by weight in the total solid content of the curable conductive adhesive composition. In order to obtain an isotropic conductive adhesive layer, the conductive filler (D) is preferably 40% by weight or more and 90% by weight or less in the total solid content of the curable conductive adhesive composition.

(Electromagnetic wave shielding film)
The curable conductive adhesive composition of the present invention can also be used as a conductive adhesive layer in an electromagnetic wave shielding film. Such an electromagnetic wave shielding film is also one aspect of the present invention.
The electromagnetic wave shielding film of the present invention preferably has a conductive adhesive layer and a protective layer. The conductive adhesive layer is obtained from a curable conductive adhesive composition. It does not specifically limit as a protective layer, A well-known arbitrary thing can be used. Furthermore, the protective layer may use a resin component (excluding the conductive filler) used in the above-described conductive adhesive layer.

The electromagnetic wave shielding film preferably has a thickness of the conductive adhesive layer in the range of 3 to 30 μm. If the thickness is less than 3 μm, sufficient connection with the ground circuit may not be obtained, and if it exceeds 30 μm, it is not preferable in that the demand for thinning cannot be met.

Next, the specific aspect of the manufacturing method of the electromagnetic wave shielding film of this invention is demonstrated.

For example, a protective layer resin composition is coated and dried on one surface of a peelable film, a protective layer is formed, and the curable conductive adhesive composition is coated and dried on the protective layer, and then conductive. And the like, and the like.

By the production method as exemplified, an electromagnetic wave shielding film in a laminated state of conductive adhesive layer / protective layer / peelable film can be obtained.

As a method of providing a conductive adhesive layer and a protective layer, conventionally known coating methods such as gravure coating method, kiss coating method, die coating method, lip coating method, comma coating method, blade coating method, roll coating method, knife coating It can be performed by a method, a spray coating method, a bar coating method, a spin coating method, a dip coating method, or the like.

The electromagnetic wave shielding film can be adhered on the substrate by hot pressing. The conductive adhesive layer is softened by heating and flows into the ground portion from which the insulator layer has been removed by pressurization. Thereby, it is electrically connected to the ground circuit.

A circuit board using such a conductive adhesive is shown in FIG. In FIG. 1, a conductive adhesive layer 3 and a protective layer 1 are formed so as to be in contact with the ground portion 4. Since the conductive adhesive layer 3 of the present invention has appropriate fluidity, the embedding property is good, and a good electrical connection can be made at the ground portion 4.

(Electromagnetic wave shielding film having a metal layer)
The electromagnetic wave shielding film of the present invention may have a metal layer. By having a metal layer, better electromagnetic shielding performance can be obtained.
Examples of the metal material forming the metal layer include nickel, copper, silver, tin, gold, palladium, aluminum, chromium, titanium, zinc, and an alloy containing any one or more of these materials. Can do. The metal material and thickness of the metal layer may be appropriately selected according to the required electromagnetic shielding effect and repeated bending / sliding resistance, but the thickness may be about 0.1 μm to 8 μm. . Examples of the method for forming the metal layer include an electrolytic plating method, an electroless plating method, a sputtering method, an electron beam evaporation method, a vacuum evaporation method, a CVD method, and a metal organic. The metal layer may be a metal foil.

The electromagnetic wave shielding film having such a metal layer can be produced by the same method as the electromagnetic wave shielding film described above, and preferably has a configuration of conductive adhesive layer / metal layer / protective layer / peelable film. .

A circuit board using an electromagnetic wave shielding film having a metal layer is shown in FIG. In FIG. 2, the metal layer 2 is electrically connected to the ground portion 4 through the conductive adhesive layer 3 to obtain electromagnetic shielding performance. At that time, since the conductive adhesive layer 3 has appropriate fluidity, the embedding property is good, and a good electrical connection can be made in the ground portion 4.
As an adherend to which the electromagnetic wave shielding film of the present invention can be attached, for example, a flexible substrate that is repeatedly bent can be given as a representative example. Of course, it can also be applied to rigid printed wiring boards. Further, not only a single-sided shield but also a double-sided shield is included.
The electromagnetic wave shielding film can be bonded onto the substrate by heating and pressing. Such hot pressing in heating and pressurization can be performed under normal conditions, for example, under conditions of 1 to 5 MPa, 140 to 190 ° C., and 15 to 90 minutes.

(Conductive adhesive film)
The present invention is also a conductive adhesive film having a conductive adhesive layer obtained using the curable conductive adhesive composition described above. Such a film can be used for bonding the conductive reinforcing plate and the circuit board main body to impart electromagnetic wave shielding performance to the reinforcing plate.

The conductive adhesive film of the present invention may be a single layer or may include a peelable film and a conductive adhesive layer formed on the surface of the peelable film. The coating method and drying conditions of the conductive adhesive film of the present invention can be performed by known methods. The conductive adhesive film of the present invention can be produced by coating a peelable film with a curable conductive adhesive composition to form a conductive adhesive layer. The coating method is not particularly limited, and a coating method used in the above-described method for producing a conductive adhesive layer in the electromagnetic wave shielding film can be employed.

For the peelable film, use is made of a base film such as polyethylene terephthalate or polyethylene naphthalate coated with a silicon-based or non-silicon-based release agent on the surface on which the conductive adhesive layer is formed. be able to. In addition, the thickness of a peelable film is not specifically limited, It determines suitably considering the ease of use.

The thickness of the conductive adhesive film is preferably 15 to 100 μm. Such a thickness is preferable in that it can be deformed into a shape that fills the concave portion by appropriately flowing when the substrate has irregularities, and can be bonded with good adhesion.

(Adhesion method)
The conductive adhesive film of the present invention can be used, for example, to bond a reinforcing plate and a circuit board body. In particular, when the reinforcing plate is made of metal, the reinforcing plate is used not only for bonding the metal reinforcing plate but also for electrically connecting with the ground electrode in the circuit board body. The adhesion method for use in such applications will be described in detail below.

The material of the circuit board body may be any material as long as it has insulating properties and can form an insulating layer, and a typical example thereof is polyimide resin.

A metal plate is preferably used as the conductive reinforcing plate, and a stainless plate, an iron plate, a copper plate, an aluminum plate, or the like can be used as the metal plate. Among these, it is more preferable to use a stainless steel plate. By using a stainless steel plate, it has sufficient strength to support an electronic component even with a thin plate thickness. The thickness of the conductive reinforcing plate is not particularly limited, but is preferably 0.025 to 2 mm, and more preferably 0.1 to 0.5 mm. If the conductive reinforcing plate is within this range, it can be easily built into a small device and has sufficient strength to support the mounted electronic component.
In addition, examples of the electronic component here include a chip component such as a resistor, a capacitor, and a camera module in addition to a connector and an IC.

In the bonding of the present invention, the conductive adhesive film obtained by the step (1) and the step (1) of temporarily bonding the above-described conductive adhesive film onto the adherend substrate (X) which is a reinforcing plate or a flexible substrate. This is a bonding method comprising a step (2) of overlaying a substrate to be bonded (X) having a flexible substrate or a substrate to be bonded (Y) as a reinforcing plate and hot pressing.

The conductive adhesive film described above can be particularly suitably used for bonding the flexible substrate and the reinforcing plate. That is, as described in Patent Document 3, a conductive material such as a metal plate is used as a reinforcing plate, and this is adhered to a flexible substrate with a conductive adhesive film, so that the electromagnetic shielding performance by the reinforcing plate can be obtained. Getting is done.

With such a technique, the conductive adhesive film of the present invention has a particularly excellent effect in that good adhesive performance is obtained when the reinforcing plate is bonded. That is, when temporary bonding is performed and stored for a certain period of time, and then main bonding is performed by hot pressing, an appropriate curing reaction proceeds during storage, so that the bonding performance of the main bonding does not deteriorate. Furthermore, since there is a moderate fluidity, even if the flexible substrate has a step, a high degree of adhesion can be obtained without causing a gap when the resin flows appropriately.

In the bonding method of the present invention, first, a conductive adhesive film is temporarily bonded onto the adherend substrate (X). The adherend substrate (X) may be a reinforcing plate or a flexible substrate, but is preferably a reinforcing plate. The conditions for temporary bonding are not particularly limited, as long as the conductive adhesive film is fixed on the substrate to be bonded and can be bonded without slipping, but it is not point bonding but surface bonding. It is preferable to do. That is, it is preferable to temporarily bond the entire bonding surface.

The temporary adhesion can be performed by, for example, a press machine (conditions temperature: 120 ° C. pressure: 0.5 MPa time: 5 seconds).

The adherend substrate (X) to which the conductive adhesive film has been temporarily bonded in the step (1) described above may be immediately used for the step (2), or for one week before being used for the step (2). It may be stored to some extent. The adhesive composition of the present invention is preferable in this respect because the adhesive performance does not deteriorate even after being partially cured.

Step (2) is a step in which the adherend substrate (Y), which is a flexible substrate or a reinforcing plate, is stacked on the adherend substrate (X) having the conductive adhesive film obtained in the step (1), and then hot-pressed. is there. One of the adherend substrate (X) and the adherend substrate (Y) is a reinforcing plate and the other is a flexible substrate.

Hot press can be performed on normal conditions, for example, 1-5 Mpa, 140-190 degreeC, 15-90 minutes.

(Circuit board)
The circuit board of the present invention is a circuit board having at least a portion where a flexible substrate, a conductive adhesive film, and a conductive reinforcing plate are laminated in this order. Such a circuit board may be bonded by the above-described bonding method, or may be obtained by other bonding methods. A schematic diagram of such a circuit board is shown in FIG. In FIG. 3, the circuit board and the reinforcing plate 5 are bonded by the conductive adhesive film of the present invention and are also electrically connected.

In the circuit board, the conductive reinforcing plate is preferably present only in a part of the circuit board. That is, it is preferable that the portion having the electronic component has a reinforcing plate.

Further, the circuit board of the present invention may be a circuit board in which the reinforcing plate is bonded to the substrate by the above-described conductive adhesive of the present invention and is covered with an electromagnetic wave shielding film in a portion having no reinforcing plate. Good. Such a circuit board is also one aspect of the present invention. Although the electromagnetic wave shielding film of this invention mentioned above may be sufficient as the electromagnetic wave shielding film used here, a well-known electromagnetic wave shielding film can be used, without being limited to it. The electromagnetic wave shielding film is preferably connected to a ground circuit (not shown).

<Second embodiment>
In this embodiment, the configurations of the polyurethane resin (A ′) and the additive (C ′) are different from those of the first embodiment, and other configurations are the same as those of the first embodiment. Therefore, description is abbreviate | omitted about the structure similar to 1st embodiment.

(Polyurethane resin (A '))
The polyurethane resin (A ′) used in the present embodiment has a carboxyl group. By having such a reactive functional group, the resin flow can be controlled by the effect that the thermal softening temperature can be controlled.

The polyurethane resin (A ′) used in the present embodiment includes a polyol compound (1) containing a carboxyl group, a polyol (2), a short-chain diol compound (3) if necessary, and a polyamine compound (if necessary). It is obtained by reacting 4) with the polyisocyanate compound (5).
More preferably, the polyurethane resin (A ′) is a polyol compound (1) containing a carboxyl group, a polyol (2), a short-chain diol compound (3) and / or a diamine compound (4) used as necessary. ) Active hydrogen-containing groups (excluding the carboxyl group of the polyol compound (1)) and the isocyanate group of the polyisocyanate compound (5) are reacted in an equivalent ratio of 0.5 to 1.5. In addition, as these compounds (1) to (5), those listed in the first embodiment are preferably used.

(Production method of polyurethane resin (A´))
The polyurethane resin (A ′) of the present embodiment can be produced by a conventionally known polyurethane production method. Specifically, first, in the presence or absence of an organic solvent containing no active hydrogen in the molecule, a polyol compound (1) containing a carboxyl group, a polyol (2), and a chain extender as necessary. Reaction product comprising a short-chain diol compound (3) used as needed, a polyamine compound (4) used as necessary, and a polyisocyanate compound (5) to react with each other (for example, polyurethane resin, prepolymer) Get. In general, the prepolymer may be a compounding composition that forms a prepolymer having a terminal isocyanate group. Moreover, what is necessary is just to make it react until it becomes theoretical isocyanate% by 20-150 degreeC normally by the one shot method or a multistage method, Preferably it is 60-110 degreeC.

The obtained reaction product (prepolymer) may be chain-extended so as to have a desired molecular weight by reacting the diamine compound (4), if necessary. Further, the total active hydrogen-containing group of the polyol compound (1), polyol (2), short chain diol compound (3), and polyamine compound (4) containing a carboxyl group (excluding the carboxyl group of the compound (1)). And the isocyanate group of the polyisocyanate compound (5) are preferably reacted at an equivalent ratio of 0.5 to 1.5.

  The polyurethane resin obtained as described above preferably has a weight average molecular weight (Mw) of 1,000 to 1,000,000, more preferably 2,000 to 1,000,000. Since characteristics, such as a softness | flexibility, adhesiveness, heat resistance, and coating performance, are exhibited more effectively, it is more preferable. In the present specification, “weight average molecular weight (Mw)” and “number average molecular weight (Mn)” mean values in terms of polystyrene measured by gel permeation chromatography (GPC) unless otherwise specified. .

As the acid value of the urethane resin is higher, the crosslinking point is increased and the heat resistance is improved. However, a urethane resin having an acid value that is too high may be too hard to reduce flexibility, or may not be able to react with an epoxy resin or a curing agent, resulting in reduced durability. For this reason, it is preferable that the acid value of a urethane resin is 3-100 mgKOH / g, and it is further more preferable that it is 3-50 mgKOH / g.

In this embodiment, a catalyst can be used as needed in the urethane synthesis. For example, salts of metals and organic and inorganic acids such as dibutyltin laurate, dioctyltin laurate, stannous octoate, zinc octylate, tetra-n-butyl titanate, and organic amine derivatives such as organometallic derivatives, triethylamine, diaza Bicycloundecene catalysts and the like can be mentioned.

The polyurethane resin may be synthesized without using a solvent or may be synthesized with an organic solvent. As the organic solvent, an organic solvent inert to the isocyanate group or an organic solvent less active than the reaction component with respect to the isocyanate group can be used. Specific examples of organic solvents include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; toluene, xylene, swazole (trade name, manufactured by Cosmo Oil Co., Ltd.), Solvesso (trade name, manufactured by Exxon Chemical Co., Ltd.) Aromatic hydrocarbon solvents such as n-hexane; Alcohol solvents such as methanol, ethanol and isopropyl alcohol; Ether solvents such as dioxane and tetrahydrofuran; Ethyl acetate, butyl acetate and isobutyl acetate Ester solvents such as ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, 3-methyl-3-methoxybutyl acetate, ethyl-3-ethoxypropionate, etc. Ether-based solvents; dimethylformamide, amide solvents such as dimethylacetamide; lactams solvents such as N- methyl-2-pyrrolidone and the like.

In the urethane synthesis, when an isocyanate group remains at the end of the polymer, it is also preferable to perform a termination reaction of the isocyanate group. The termination reaction of the isocyanate group can be performed using a compound having reactivity with the isocyanate group. As such a compound, a monofunctional compound such as monoalcohol or monoamine; a compound having two kinds of functional groups having different reactivity with respect to isocyanate can be used. Specific examples of such compounds include monoalcohols such as methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, and tert-butyl alcohol.

(Additive (C '))
The additive (C ′) of the present embodiment is a compound that does not correspond to the polyurethane resin (A ′) or the epoxy resin (B) described above, and is used for the curing reaction of the curable conductive adhesive composition of the present embodiment. It refers to a compound having a functional group involved. In particular, it is preferable to be able to react with a carboxyl group in the polyurethane resin (A ′) or a hydroxyl group in the epoxy resin (B) from the viewpoint of improving heat resistance and adhesion.

The compound that can be used as such an additive (C ′) is not particularly limited. For example, conventionally known additives such as an isocyanate compound, a blocked isocyanate compound, a carbodiimide compound, an oxazoline compound, a melamine, and a metal complex crosslinking agent are used. Can be used. Among these additives, an isocyanate compound, a blocked isocyanate compound, a carbodiimide compound, and an oxazoline compound are preferable. These are compounds having two or more reactive groups such as an isocyanate group, a blocked isocyanate group, a carbodiimide group, and an oxazoline group. Examples of commercially available isocyanate compounds that can be used as additives include duranate (manufactured by Asahi Kasei Chemicals Corporation). Examples of commercially available carbodiimide compounds include carbodilite (Nisshinbo Chemical Co., Ltd.). Examples of commercially available oxazoline compounds include Epocross (manufactured by Nippon Shokubai Co., Ltd.). Two or more of these compounds may be used in combination.

Examples of the isocyanate compound include toluene-2,4-diisocyanate, 4-methoxy-1,3-phenylene diisocyanate, 4-isopropyl-1,3-phenylene diisocyanate, 4-chloro-1,3-phenylene diisocyanate, 4 -Butoxy-1,3-phenylene diisocyanate, 2,4-diisocyanate diphenyl ether, 4,4'-methylenebis (phenylene isocyanate) (MDI), durylene diisocyanate, tolidine diisocyanate, xylylene diisocyanate (XDI), 1,5-naphthalene Aromatic diisocyanates such as diisocyanate, benzidine diisocyanate, o-nitrobenzidine diisocyanate, 4,4′-diisocyanate dibenzyl; methylene diisocyanate Aliphatic diisocyanates such as 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,10-decamethylene diisocyanate; 1,4-cyclohexylene diisocyanate, 4,4-methylenebis (cyclohexyl isocyanate), 1 , 5-tetrahydronaphthalene diisocyanate, isophorone diisocyanate, hydrogenated MDI, hydrogenated XDI, and other alicyclic diisocyanates; obtained by reacting these diisocyanates with low molecular weight polyols or polyamines so that the ends are isocyanates. Polyurethane prepolymers and the like, and isocyanurate bodies, burette bodies, adduct bodies, and polymeric bodies of these isocyanate compounds. Those having a group, known which are conventionally used can be used is not particularly limited.

As said blocked isocyanate compound, the compound which blocked the isocyanate compound of the isocyanate compound mentioned above by the well-known method can be used. The blocking compound is not particularly limited, and phenols such as phenol, cresol, xylenol, chlorophenol and ethylphenol; lactams such as ε-caprolactam, δ-valerolactam, γ-butyrolactam and β-propiolactam; aceto Active methylene such as ethyl acetate and acetylacetone; methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, t-butanol, amyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, ethylene glycol Mono 2-ethylhexyl ether, propylene glycol monomethyl ether, methyl glycolate, butyl glycolate, diacetone alcohol Alcohol, methyl lactate and ethyl lactate, furfuryl alcohol, etc .; formaldoxime, acetoaldoxime, acetoxime, methylethylketoxime, diacetylmonooxime, cyclohexaneoxime, and other oxime systems; butyl mercaptan, hexyl mercaptan, t-butyl Mercaptans such as mercaptan, thiophenol, methylthiophenol and ethylthiophenol; acid amides such as acetic acid amide and benzamide; imides such as succinimide and maleic imide; imidazoles such as imidazole and 2-ethylimidazole; dimethyl Secondary amines such as amine, diethylamine and dibutylamine; pyrazoles such as pyrazole, 3-methylpyrazole, 3,5-dimethylpyrazole and the like can be mentioned.

It does not specifically limit as said carbodiimide compound, For example, what was obtained by the decarboxylation condensation reaction of the isocyanate compound mentioned above etc. can be mentioned.

The oxazoline compound is not particularly limited, and examples thereof include 2,2'-bis- (2-oxazoline), 2,2'-methylene-bis- (2-oxazoline), 2,2'-ethylene-bis- ( 2-oxazoline), 2,2'-trimethylene-bis- (2-oxazoline), 2,2'-tetramethylene-bis- (2-oxazoline), 2,2'-hexamethylene-bis- (2-oxazoline) ), 2,2'-octamethylene-bis- (2-oxazoline), 2,2'-ethylene-bis- (4,4-dimethyl-2-oxazoline), 2,2 '-(1,3-phenylene) ) -Bis- (2-oxazoline), 2,2 '-(1,3-phenylene) -bis- (4,4-dimethyl-2-oxazoline), 2,2'-(1,4-phenylene)- Bis- (2-oxazoly ), Bis- (2-oxazolinylcyclohexane) sulfide, dioxazoline compounds such as bis- (2-oxazolinylnorbornane) sulfide; 2,2 ′-(1,2,4-phenylene) -tris- (2 -Oxazoline) and the like; and oxazoline group-containing polymers such as styrene / 2-isopropenyl-2-oxazoline copolymer.

The additive (C ′) is preferably not an aziridine compound. That is, it is preferable not to use an aziridine compound since mutagenicity (Ames) is positive.

The amount of the additive (C ′) used is preferably 0.1 to 200 parts by mass or less, based on 100 parts by mass of the resin component of the polyurethane resin (A ′), and is 0.2 to 100 parts by mass. More preferably. By setting it within the above range, it is preferable in terms of easy adjustment of heat resistance.

The curable conductive adhesive composition according to the second embodiment can also be used in the electromagnetic wave shielding film, the circuit board, and the bonding method in the same manner as in the first embodiment.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified.

<First embodiment>
[Synthesis Example A-1: Polycarboxylate-containing polyurethane resin (double bond introduced)]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. After replacing the inside of the reaction vessel with nitrogen gas, 6.0 g of dimethylolpropionic acid (DMPA), polyhexamethylene carbonate diol (trade name “Placcel CD220”, manufactured by Daicel Corporation, number average molecular weight 2000 by terminal functional group determination, 2000 ) 100 g, 12.0 g of glycerol monomethacrylate (trade name “Blenmer GLM”, manufactured by NOF Corporation, molecular weight 160), and 75.0 g of dimethylformamide (DMF) were charged. Next, 57.0 g of hexamethylene diisocyanate (HDI) (2 times equivalent of NCO group to OH group) was added, and the reaction was carried out at 90 ° C. until the NCO group of the resin reached 5.7% of the theoretical value. A prepolymer solution was obtained. After adding 400.5 g of DMF to the obtained urethane prepolymer solution and cooling to 40 ° C., 28.8 g of isophoronediamine (IPDA) was added dropwise to react with the NCO group of the urethane prepolymer. Stir until the absorption at 2,270 cm −1 due to the free isocyanate group disappeared as measured by infrared absorption spectrum analysis, and the polyurethane resin (A with an acid value of 12.3 mg KOH / g and a double bond equivalent of 2700 g / eq) -1) DMF solution (solid content concentration 30%) was obtained.

[Synthesis Example A-2: Polycarboxylate-containing polyurethane resin (hydroxyl group introduction)]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. After replacing the inside of the reaction vessel with nitrogen gas, 6.0 g of DMPA, 100 g of CD220, and 59.1 g of DMF were charged. Next, 31.8 g of HDI (NCO group is twice equivalent to OH group) was added, and the reaction was carried out at 90 ° C. until the NCO group of the resin reached 4.0% of the theoretical value to obtain a urethane prepolymer solution. . DMF285.3g was added to the obtained urethane prepolymer solution, and after cooling to 40 degreeC, N- (aminoethyl) ethanolamine 9.8g was dripped and it was made to react with the NCO group of a urethane prepolymer. Stir until absorption at 2,270 cm −1 due to the free isocyanate group disappears as measured by infrared absorption spectrum analysis, and a polyurethane resin having an acid value of 17.0 mg KOH / g and a hydroxyl value of 35.8 mg KOH / g (A -2) DMF solution (solid content concentration 30%) was obtained.

[Synthesis Example A-3: Carboxyl group-containing polyurethane resin (methoxysilyl group introduction)]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. After replacing the inside of the reaction vessel with nitrogen gas, 6.0 g of DMPA, 100 g of CD220, and 59.1 g of DMF were charged. Next, 31.8 g of HDI (NCO group is twice equivalent to OH group) was added, and the reaction was carried out at 90 ° C. until the NCO group of the resin reached 4.0% of the theoretical value to obtain a urethane prepolymer solution. . After adding 311.4 g of DMF to the obtained urethane prepolymer solution and cooling to 40 ° C., N-2- (aminoethyl) -3-aminopropyltrimethoxysilane (trade name “KBM-603”, Shin-Etsu Chemical Co., Ltd.) 21.0 g (manufactured by Kogyo Co., Ltd.) was added dropwise to react with the NCO group of the urethane prepolymer. Stir until the absorption at 2,270 cm −1 by the free isocyanate group disappears as measured by infrared absorption spectrum analysis, and a polyurethane resin (A with an acid value of 15.8 mg KOH / g and a silicon content of 1.7 wt%) -3) was obtained (solid content concentration 30%).

[Comparative Synthesis Example A-4: Polyurethane resin without carboxyl group]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. After the inside of the reaction vessel was replaced with nitrogen gas, 4.0 g of 1,4-butanediol, 100 g of CD220, and 58.2 g of DMF were charged. Next, 31.7 g of HDI (NCO group was 2 times equivalent to OH group) was added, and the reaction was carried out at 90 ° C. until the NCO group of the resin reached 4.1% of the theoretical value to obtain a urethane prepolymer solution. . After adding 295.8 g of DMF to the obtained urethane prepolymer solution and cooling to 40 ° C., 16.0 g of IPDA was added dropwise to react with the NCO group of the urethane prepolymer. Stir until the absorption at 2,270 cm −1 by the free isocyanate group disappears, as measured by infrared absorption spectrum analysis, and a DMF solution of polyurethane resin (A-4) containing no carboxyl group (solid content concentration 30% )

[Comparative Synthesis Example A-5: Carbosyl group-containing polyurethane resin]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. After replacing the inside of the reaction vessel with nitrogen gas, 6.0 g of DMPA, 100 g of CD220, and 59.0 g of DMF were charged. Next, 31.9 g of HDI (NCO group is 2 times equivalent to OH group) was added, and the reaction was carried out at 90 ° C. until the NCO group of the resin reached 4.0% of the theoretical value to obtain a urethane prepolymer solution. . 298.5 g of DMF was added to the obtained urethane prepolymer solution, and after cooling to 40 ° C., 16.1 g of IPDA was added dropwise to react with the NCO group of the urethane prepolymer. Stir until absorption at 2,270 cm −1 due to free isocyanate groups disappeared as determined by infrared absorption spectrum analysis, and a DMF solution (solid) of polyurethane resin (A-5) having an acid value of 16.4 mg KOH / g A partial concentration of 30%).
The raw material compounding ratio of each resin and the characteristic values of the resin obtained as described above are shown in Table 1 below.

In addition, the number average molecular weight and weight average molecular weight in Table 1 are values measured under the following conditions.
1) Equipment:
HLC-8020 (Tosoh Corporation)
2) Column (manufacturing company, column name): (Tosoh Corporation TSKgel G2000HXL,
(G3000HXL, G4000GXL)
3) Solvent: THF
4) Flow rate: 1.0 ml / min
5) Sample concentration: 2 g / L
6) Injection volume: 100 μl
7) Temperature: 40 ° C
8) Detector: RI-8020
Standard material: TSK standard polystyrene (Tosoh Corporation)

(Electromagnetic wave shielding film)
A peelable film coated with a release agent was coated with a protective layer resin and dried to form a protective layer having a thickness of 5 μm. On the other hand, each material was blended as shown in Table 2 to prepare a curable conductive adhesive composition. On the protective layer, the curable conductive adhesive composition was hand-coated using a doctor blade (plate-like spatula) and dried at 100 ° C. for 3 minutes to prepare a conductive adhesive layer. The doctor blade is appropriately selected from 1 mil to 5 mil depending on the thickness of the conductive adhesive layer to be produced. Note that 1 mil = 1/1000 inch = 25.4 μm. In each example and each comparative example, the conductive adhesive layer was prepared to have a predetermined thickness. In addition, the thickness of a protective layer and a conductive adhesive layer is measured with a micrometer.

In addition, the epoxy resin shown in Table 2 was used as the epoxy resin in Table 2. The same applies to the following tables.

As the conductive fillers in Table 2, the following were used.
Conductive filler D-1: Silver powder (average particle size 5 μm, manufactured by Fukuda Metal Foil Powder Industry Co., Ltd.)
Conductive filler D-2: Silver-coated copper powder (average particle size 12 μm, manufactured by Fukuda Metal Foil Powder Co., Ltd.)
Conductive filler D-3: Silver-coated copper powder (average particle size 18 μm, manufactured by Fukuda Metal Foil Powder Co., Ltd.)

As additives in Table 2, the following were used.
Additive C-1: Park Mill H (manufactured by NOF Corporation)
Additive C-2: Duranate 24A-100 (Asahi Kasei Chemicals Corporation)
Additive C-3: Stanocto (manufactured by API Corporation)

The obtained electromagnetic wave shielding film was evaluated based on the following evaluation criteria. The results are shown in Table 4.
(180 ° peel strength)
As shown in FIG. 6, the conductive adhesive layer side of the electromagnetic wave shielding film 27 is placed on a test plate (width 10 mm, length 100 mm) via a polyimide film 26 (manufactured by Toray DuPont Co., Ltd., Kapton 100H (trade name)). The polyimide film 26 (Kapton 100H) was attached to the protective layer side through an adhesive layer, and was peeled off from the polyimide film at 50 mm / min. The average value with n = 5 is shown in the table. If it is 3 N / cm or more, it can be used without problems.

(Connection resistance value)
The electromagnetic wave shielding film was placed on a flexible substrate simulating a ground having an opening diameter of 1.0 mm and a step of 37.5 μm, and heated at 170 ° C. for 30 minutes while being pressurized at a pressure of 3 MPa. The connection resistance of the fabricated circuit board was measured. If it is 1Ω or less, electromagnetic wave shielding performance can be secured.

(Reflow resistance)
Evaluation after reflow was performed. As the reflow temperature condition, a lead-free solder was assumed and a temperature profile of a maximum of 265 ° C. was set. A test piece of a circuit board with a metal reinforcing plate obtained by pressing a conductive adhesive film with a reinforcing plate was passed five times through IR reflow, and the presence or absence of swelling was observed.

From the results of Table 4 above, it is clear that the electromagnetic wave shielding film of the present invention is excellent in processability, and the wiring board obtained by using this film has good embedding properties and good properties.

(Electromagnetic wave shielding film having a metal thin film layer)
A peelable film coated with a release agent was coated with a protective layer resin and dried to form a protective layer with a thickness of 5 μm. About 0.1 μm of a silver thin film layer was formed on the protective layer by vacuum deposition. Each material is mix | blended as shown in Table 5, and a curable conductive adhesive composition is produced. This was hand-coated on a metal thin film layer using a doctor blade (plate-like spatula) and dried at 100 ° C. for 3 minutes to produce a conductive adhesive layer. The doctor blade is appropriately selected from 1 mil to 5 mil depending on the thickness of the conductive adhesive layer to be produced. Note that 1 mil = 1/1000 inch = 25.4 μm. In each example and each comparative example, the conductive adhesive layer was prepared to have a predetermined thickness. In addition, the thickness of a protective layer and a conductive adhesive layer is measured with a micrometer.

As the conductive filler in Table 5, the same one as used in Table 2 was used.

Evaluation was performed by the same evaluation method as that for the electromagnetic wave shielding film having no metal thin film layer described above, and the results are shown in Table 6.

From the results of Table 6 above, it is clear that the electromagnetic wave shielding film of the present invention is excellent in workability, and the wiring board obtained using the film has good properties.

(Method for producing conductive adhesive film)
The manufacturing method of the electroconductive adhesive film of each Example and each comparative example is demonstrated. Each material is mix | blended as shown in Table 7, and a curable conductive adhesive composition is produced. This was hand-coated using a doctor blade (plate-like spatula) on a polyethylene terephthalate film subjected to a mold release treatment, and dried at 100 ° C. for 3 minutes to produce a conductive adhesive film. The doctor blade is appropriately selected from 1 mil to 5 mil depending on the thickness of the conductive adhesive film to be produced. Note that 1 mil = 1/1000 inch = 25.4 μm. In addition, in each Example and each comparative example, it produced so that the thickness of a conductive adhesive film might become predetermined thickness. The thickness of the conductive adhesive film is measured with a micrometer.

As the conductive fillers in Table 7, the following were used.
Conductive filler D-4: Silver powder (average particle size 12 μm, Fukuda Metal Industry Co., Ltd.)
Conductive filler D-5: Silver-coated copper powder (average particle size 20 μm, Fukuda Metal Industry Co., Ltd.)
Conductive filler D-6: Silver-coated copper powder (average particle size 25 μm, Fukuda Metal Industry Co., Ltd.)

The obtained conductive adhesive film was evaluated based on the following evaluation criteria.
(Peel strength)
The adhesion with the reinforcing plate was measured using a 90 ° peel test. Specifically, as shown in FIG. 4, the surface side of the polyimide layer in the copper-clad laminates 22 and 23 having a stainless steel plate 24 (width 10 mm, length 100 mm), a polyimide layer and a thin-film copper layer, and the book After press bonding as described in the method of using the conductive adhesive film of the above embodiment via the conductive adhesive film 21 of the example, the copper-clad laminate was pulled off in the vertical direction. If it is 10 N / cm or more, it can be used without problems.

(Connection resistance value)
Electrical evaluation was performed on the circuit board with the metal reinforcing plate 5 manufactured by the above method. Connection resistance of a circuit board with a metal reinforcing plate when a conductive adhesive film is pressed with a reinforcing plate on a flexible substrate simulating a ground having an opening diameter of 1.0 mm and a step of 37.5 μm (see FIG. 5 between the electrodes 8). If it is 1Ω or less, it is judged that the shielding performance is ensured and the embeddability is good.

(Reflow resistance)
Evaluation after reflow was performed. As the reflow temperature condition, a lead-free solder was assumed and a temperature profile of a maximum of 265 ° C. was set. A test piece of a circuit board with a metal reinforcing plate obtained by pressing a conductive adhesive film with a reinforcing plate was passed five times through IR reflow, and the presence or absence of swelling was observed.

(Resin flow)
The resin flow distance was measured about the circuit board with a metal reinforcement board produced by said method. When the produced circuit board with a metal reinforcing plate was observed from the reinforcing plate side, the distance between the end of the conductive adhesive protruding from the bottom of the reinforcing plate and the end of the reinforcing plate was measured. If it is 300 micrometers or less, it can be used without a problem. (See Figure 7)

Table 8 shows the evaluation results of the obtained functional film.

<Second embodiment>
The curable conductive property is the same as in the first embodiment except that the polyurethane resin (A ′) and the additive (C ′) are used instead of the polyurethane resin (A) and the additive (C) of the first embodiment. An adhesive composition was prepared. Unless otherwise specified, various measurement conditions and evaluation conditions are the same as those in the first embodiment.

(Polyurethane resin (A '))
[Synthesis Example A′-1: Polycarboxylate-containing polyurethane (with urea bond)]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. After the inside of the reaction vessel was replaced with nitrogen gas, dimethylolpropionic acid (DMPA) 6.0 g, polyhexamethylene carbonate diol (trade name “Placcel CD220”, manufactured by Daicel, number average molecular weight 2000 by terminal functional group determination) 100 g and 59.1 g of dimethylformamide (DMF) were charged. Next, 31.8 g of hexamethylene diisocyanate (HDI) (NCO group is twice equivalent to OH group) was added, and the reaction was carried out at 90 ° C. until the NCO group of the resin reached 4.0% of the theoretical value. A prepolymer solution was obtained. To the obtained urethane prepolymer solution, 300.0 g of DMF was added and cooled to 40 ° C., and then 16.1 g of isophorone diamine (IPDA) was added dropwise to react with the NCO group of the urethane prepolymer. Stir until the absorption at 2,270 cm −1 due to the free isocyanate group disappeared as measured by infrared absorption spectrum analysis, and a DMF solution of polyurethane resin (A′-1) having an acid value of 16.3 mg KOH / g ( Solid content concentration 30%) was obtained.

[Synthesis Example A′-2: Polyurethane containing carboxyl group (no urea bond)]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. After replacing the inside of the reaction vessel with nitrogen gas, DMPA 6.0 g, 1,4-butanediol 6.0 g, Plaxel CD220 100 g, and DMF 139.1 g were charged. Next, 27.1 g of HDI (NCO group equivalent to OH group) was added, and the mixture was stirred at 90 ° C. until 2,270 cm −1 absorption due to free isocyanate groups disappeared as measured by infrared absorption spectrum analysis. Then, 185.5 g of DMF was added to obtain a DMF solution (solid content concentration 30%) of polyurethane resin (A′-2) having an acid value of 18.1 mg KOH / g. It was confirmed by infrared absorption spectrum that the polyurethane resin d2 has no urea bond.

[Synthesis Example A′-3: Polycarboxylate-containing polyurethane (with urea bond)]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. After replacing the inside of the reaction vessel with nitrogen gas, 6.0 g of DMPA, 100 g of Plaxel CD220, and 70.8 g of DMF were charged. Next, 42.1 g of isophorone diisocyanate (IPDI) (2 times equivalent of NCO group to OH group) was added, and the reaction was carried out at 90 ° C. until the NCO group of the resin reached 4.0% of the theoretical value. A polymer solution was obtained. After adding 312.3 g of DMF to the obtained urethane prepolymer solution and cooling to 40 ° C., 16.1 g of IPDA was added dropwise to react with the NCO group of the urethane prepolymer. Stir until the absorption at 2,270 cm −1 due to the free isocyanate group disappeared, as measured by infrared absorption spectrum analysis, and a DMF solution of polyurethane resin (A′-3) having an acid value of 16.3 mg KOH / g ( Solid content concentration 30%) was obtained.

[Comparative Synthesis Example A′-4: No carboxyl group]
A reaction vessel equipped with a stirrer, a reflux condenser, a thermometer, a nitrogen blowing tube, and a manhole was prepared. After the inside of the reaction vessel was replaced with nitrogen gas, 4.0 g of 1,4-butanediol, 100 g of CD220, and 58.2 g of DMF were charged. Next, 31.7 g of HDI (NCO group was 2 times equivalent to OH group) was added, and the reaction was carried out at 90 ° C. until the NCO group of the resin reached 4.1% of the theoretical value to obtain a urethane prepolymer solution. . After adding 295.8 g of DMF to the obtained urethane prepolymer solution and cooling to 40 ° C., 16.0 g of IPDA was added dropwise to react with the NCO group of the urethane prepolymer. Stir until the absorption at 2,270 cm −1 due to free isocyanate groups disappeared as measured by infrared absorption spectrum analysis, and a DMF solution of polyurethane resin (A′-4) containing no carboxyl group (solid content concentration 30 %).

Table 9 shows the composition of the obtained polyurethane resin.

(Electromagnetic wave shielding film)
An electromagnetic wave shielding film was produced by the same method as the production method of the electromagnetic wave shielding film in the first embodiment except that the composition of each material of the conductive adhesive composition was as shown in Table 10.

In addition, the epoxy resin in Table 10 was the same as that shown in Table 11 below. The same applies to the following tables.

As the crosslinking agent in Table 10, the following were used.
Crosslinking agent C′-1: carbodiimide compound; Carbodilite V-07 (manufactured by Nisshinbo Chemical Co., Ltd.)
Cross-linking agent C′-2: oxazoline compound; Epocross RPS-1005 (manufactured by Nippon Shokubai Co., Ltd.)
Cross-linking agent C′-3: isocyanate compound; Duranate 24A-1000 (Asahi Kasei Chemicals Corporation)
Cross-linking agent C′-4: Block isocyanate compound; Duranate 17B-60PX (Asahi Kasei Chemicals Corporation)
Moreover, the following were used as a conductive filler in Table 10.
Conductive filler D-1: Silver powder (average particle size 5 μm, Fukuda Metal Industry Co., Ltd.)
Conductive filler D-2: Silver-coated copper powder (average particle size 12 μm, Fukuda Metal Industry Co., Ltd.)
Conductive filler D-3: Silver-coated copper powder (average particle size 18 μm, Fukuda Metal Industry Co., Ltd.)

The 180 ° peel strength, connection resistance value, and reflow resistance of the obtained electromagnetic wave shielding film were evaluated based on the same evaluation criteria as in the first embodiment. The results are shown in Table 12.

From the results of Table 12 above, it is clear that the electromagnetic wave shielding film of this embodiment is excellent in workability, and the wiring board obtained using this film has good embedding properties and good properties.

(Electromagnetic wave shielding film having a metal thin film layer)
The metal thin film layer was formed by the same method as the method for producing the electromagnetic wave shielding film having the metal thin film layer in the first embodiment except that the composition of each material of the curable conductive adhesive composition was as shown in Table 13. The electromagnetic shielding film which has was obtained.

Evaluation was performed by the same evaluation method as that for the electromagnetic wave shielding film having no metal thin film layer described above. The results are shown in Table 14.

From the results of Table 14 above, it is clear that the electromagnetic wave shielding film of the present embodiment is excellent in workability, and the wiring board obtained using this film has good properties.

(Method for producing conductive adhesive film)
A conductive adhesive film was produced by the same method as the method for producing a conductive adhesive film in the first embodiment except that the composition of each material of the curable conductive adhesive composition was as shown in Table 15.

The peel strength, connection resistance value, reflow resistance, and resin flow of the obtained conductive adhesive film were evaluated based on the same evaluation criteria as in the first embodiment.

Table 16 shows the evaluation results of the obtained functional film.

The curable conductive adhesive composition of the present invention can be used particularly preferably in the fields of applications such as bonding a metal reinforcing plate to a flexible substrate and electromagnetic shielding films.

1. Protective layer 2. 2. Metal layer 3. Conductive adhesive layer Ground part (Ni-Au electroless plating treatment)
5. Metal reinforcement plate (Ni-SUS)
6). 6. Coverlay film Copper-clad laminate 8. Electrode (Ni-Au electroless plating treatment)
9. 12. Connection resistance measurement point Resin flow 21. Conductive adhesive film 22.23. Copper clad laminate 24. Stainless plate 26. Polyimide film 27. Electromagnetic shielding film

Claims (17)

A polyurethane resin (A) having at least one functional group selected from the group consisting of a carboxyl group and a hydroxyl group, a carbon-carbon unsaturated bond and an alkoxysilyl group;
An epoxy resin (B) having two or more epoxy groups per molecule;
At least one additive (C) selected from the group consisting of a crosslinking agent, a polymerization initiator and a tin-based metal catalyst;
A curable conductive adhesive composition comprising a conductive filler (D). Epoxy resin (B)
Epoxy resin (B1) having an epoxy equivalent of 800 to 10,000 and
Epoxy resin having an epoxy equivalent of 90 to 300 (B2)
The curable conductive adhesive composition according to claim 1, comprising at least one of the following. A polyurethane resin (A ′) having a carboxyl group;
An epoxy resin (B) having two or more epoxy groups per molecule;
At least one additive (C ′) selected from the group consisting of an isocyanate compound, a blocked isocyanate compound and an oxazoline compound;
Containing a conductive filler (D) ,
Epoxy resin (B)
Epoxy resin (B1) having an epoxy equivalent of 800 to 10,000 and
Containing an epoxy resin (B2) having an epoxy equivalent of 90 to 300,
The mixing ratio of the polyurethane resin (A ′) and the epoxy resin (B) is 70:30 to 30:70 in terms of mass ratio of the polyurethane resin (A ′) and the epoxy resin (B).
The curable conductive adhesive composition, wherein the additive (C ') is 0.1 to 200 parts by mass with respect to 100 parts by mass of the resin component of the polyurethane resin (A') . The curing according to any one of claims 1, 2, and 3 , wherein at least one of the polyurethane resin (A) and the polyurethane resin (A ') has an acid value of 3 to 100 mgKOH / g. Conductive adhesive composition. The weight average molecular weight of at least one of the polyurethane resin (A) and the polyurethane resin (A ') is 1,000 to 1,000,000, according to any one of claims 1 to 4. The curable conductive adhesive composition described. The epoxy resin (B1) is a bisphenol type epoxy resin,
The curable conductive adhesive composition according to claim 2 or 3 , wherein the epoxy resin (B2) is a novolac type epoxy resin. 7. The curable conductive adhesive according to claim 1, wherein the conductive filler (D) is at least one selected from the group consisting of silver powder, silver-coated copper powder, and copper powder. Agent composition. The curable conductive adhesive composition according to claim 1, wherein the conductive filler (D) has an average particle diameter of 3 to 50 μm. The electromagnetic wave shielding film characterized by laminating | stacking the electroconductive adhesive layer using the curable electroconductive adhesive composition of any one of Claims 1-8, and the protective layer. The electromagnetic wave shielding film characterized by laminating | stacking the conductive adhesive layer using the curable conductive adhesive composition of any one of Claims 1-8, a metal layer, and a protective layer in this order. 11. The electromagnetic wave shielding film according to claim 9, wherein the conductive adhesive layer has a thickness of 3 to 30 μm. A circuit board, wherein the conductive adhesive layer of the electromagnetic wave shielding film according to any one of claims 9 to 11 is connected to a ground of a printed board by heating and pressing. It has a conductive adhesive layer obtained using the curable conductive adhesive composition of any one of Claims 1-8, The conductive adhesive film characterized by the above-mentioned. The conductive adhesive film according to claim 13, wherein the conductive adhesive layer has a thickness of 15 to 100 μm. A conductive adhesive film obtained by the step (1) and the step (1) of temporarily bonding the conductive adhesive film according to claim 13 or 14 onto the adherend substrate (X) which is a reinforcing plate or a flexible substrate. A bonding method comprising: a step (2) of superimposing a substrate to be bonded (Y), which is a flexible substrate or a reinforcing plate, on the substrate to be bonded (X) and hot pressing. It is a circuit board which has a part which laminated | stacked the flexible substrate, the conductive adhesive layer, and the conductive reinforcement board in this order in at least one part, Comprising: A conductive adhesive layer is by the conductive adhesive film of Claim 13 or 14 A circuit board which is formed. The circuit board according to claim 16, wherein a surface other than the reinforcing plate on the surface of the flexible substrate is covered with an electromagnetic wave shielding film.