JP5258466B2 - Thermosetting adhesive composition, thermosetting adhesive tape or sheet, and flexible circuit board - Google Patents

Description

  The present invention relates to a thermosetting adhesive composition, a thermosetting adhesive tape or sheet, and a flexible circuit board. More specifically, the present invention relates to a thermosetting adhesive composition, a thermosetting adhesive tape or sheet, and a flexible circuit board that can be suitably used for flexible printed circuit boards and the like.

  In electronic devices, flexible printed circuit boards (sometimes referred to as “FPC”) are widely used. In such an FPC, (1) a process of manufacturing an FPC by bonding and laminating a conductive metal foil such as a copper foil or an aluminum foil on a heat-resistant substrate such as a polyimide substrate or a polyamide substrate, 2) An adhesive is used in the process of bonding the FPC to a reinforcing plate such as an aluminum plate, a stainless steel plate, or a polyimide plate.

  As adhesives used for bonding such FPCs, elastomer / epoxy resin adhesives have been widely used, and as adhesives for electronic devices, elastomer / phenol resin / phenol resin crosslinking agents. The adhesive comprised by these is known (refer patent document 1).

  The adhesive containing the epoxy resin has characteristics that are sufficiently satisfactory in terms of adhesive strength and heat resistance. However, since the adhesive exhibits adhesiveness due to the chemical reaction of the epoxy resin, if it is stored at room temperature before being used as an adhesive, the reaction proceeds and the function as an adhesive is lost. For this reason, there are problems such as requiring storage at low temperatures and extremely shortening the storage period.

  On the other hand, an adhesive composed of the above elastomer / phenol resin / phenolic resin crosslinking agent is excellent in storage stability as an adhesive, but in order to obtain flexibility and heat resistance in a preferable range as an adhesive. In other words, it is necessary to add a relatively large amount of the phenol resin to the elastomer. Specifically, the ratio of the mass of the phenol resin divided by the mass of the elastomer needs to be at least about 0.65. However, in such a range, since the curing reaction rate becomes too fast, there is a problem that the adhesion cannot be sufficiently performed with the adherend and the adhesiveness is insufficient, and the heat resistance is deteriorated due to poor adhesion. Also occurred.

  That is, the present condition is that the thermosetting adhesive which was excellent in the preservability (storage stability) before hardening, the heat resistance after hardening, and adhesiveness is not yet obtained.

JP-T-2006-522857

  Accordingly, an object of the present invention is to provide a thermosetting adhesive composition that has good storage stability before curing and can exhibit excellent adhesion and heat resistance after curing by heating. There is to do. That is, it is an object to provide a thermosetting adhesive composition that has inherently contradictory performance and can achieve both pre-curing preservability, adhesiveness after curing, and heat resistance, both of which have been impossible in the past. Another object of the present invention is to provide a thermosetting adhesive tape or sheet having a thermosetting adhesive layer made of the thermosetting adhesive composition, and a flexible printed circuit board.

  As a result of intensive studies to achieve the above-mentioned object, the present inventors used an acrylic polymer as an elastomer component, and further combined a hexamethylenetetramine, which is a crosslinking agent for a phenol resin and a phenol resin, with a specific formulation, It was found that a thermosetting adhesive composition having stable storage stability at room temperature before curing and capable of exhibiting excellent adhesiveness and heat resistance after curing by heating was obtained. . The present invention has been completed based on these findings.

That is, the present invention is, relative to 100 parts by weight of acrylic polymer (X), containing the phenol resin (Y) 1 to 60 parts by weight of hexamethylenetetramine (Z) 1 to 25 parts by weight, the acrylic polymer ( X) is composed of (meth) acrylic acid alkyl ester (a) having 2 to 14 carbon atoms in the alkyl group, cyano group-containing monomer (b), and carboxyl group-containing monomer (c) as essential monomer components. The monomer component constituting the acrylic polymer (X) is 50 to 75% by weight of the (meth) acrylic acid alkyl ester (a) having 2 to 14 carbon atoms of the alkyl group based on the total amount of the monomer component. And 20 to 45 wt% of the cyano group-containing monomer (b) and 0.1 to 7 wt% of the carboxyl group-containing monomer (c). Providing a thermosetting adhesive composition according to symptoms.

  Furthermore, the present invention provides a thermosetting adhesive tape or sheet having at least a thermosetting adhesive layer formed from the thermosetting adhesive composition.

  Furthermore, this invention provides the flexible circuit board which has at least the thermosetting type adhesive bond layer formed with the said thermosetting type adhesive composition.

  According to the thermosetting adhesive composition of the present invention, since it has the above-described configuration, it can exhibit stable storage stability at room temperature before curing, and is excellent after curing by heating. Adhesion and heat resistance can be exhibited. For this reason, the performance as a thermosetting adhesive agent can be exhibited with sufficient balance.

  The thermosetting adhesive composition of the present invention contains acrylic polymer (X), phenol resin (Y) and hexamethylenetetramine (Z) as essential components. The total amount (total amount) of the essential components (X), (Y) and (Z) in the total solid content of the thermosetting adhesive composition of the present invention is preferably 60% by weight or more, more preferably. 80% by weight or more.

[Acrylic polymer (X)]
The acrylic polymer (X) is not particularly limited as long as it is a polymer constituted (or formed) with an acrylic monomer as an essential monomer component (monomer component), but as a monomer component, (meth) acrylic acid C _2-14 alkyl ester (a) and cyano group-containing monomer (b) are preferably used. Furthermore, it is particularly preferable that the carboxyl group-containing monomer (c) is used. Among them, (meth) acrylic acid C _2-14 alkyl ester (a) is 50 to 75% by weight, cyano group-containing monomer (b) is 20 to 45% by weight, and carboxyl group-containing monomer with respect to the total amount of monomer components. It is preferable that it is comprised from the monomer component which contains (c) in the ratio of 0.1 to 7 weight%. As the monomer component, other monomer components other than those described above may be used.

  In the thermosetting adhesive composition of the present invention, by using an acrylic polymer as an elastomer component, by combining a specific amount of phenol resin and hexamethylenetetramine, storage stability and adhesiveness (high adhesive force, for example, The adhesive strength with adherends such as polyimide and stainless steel) and heat resistance can both be achieved. When natural rubber, synthetic rubber other than acrylic polymer, or the like is used as the elastomer component, both of the above effects cannot be achieved. In the present invention, by using an acrylic polymer as a main agent, the acrylic polymer itself can improve the bulk strength of the adhesive (adhesive layer) and improve heat resistance. Compared to the case where synthetic rubber other than acrylic polymer is used as the main ingredient, sufficient heat resistance can be obtained by synergistic effect with hexamethylenetetramine even if the blending amount of phenol resin is lowered. And the storage stability becomes more advantageous.

As the (meth) acrylic acid C _2-14 alkyl ester (a), a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 2 to 14 carbon atoms [acrylic acid alkyl ester and / Or methacrylic acid alkyl ester] is not particularly limited, but, for example, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, (meth) Isobutyl acrylate, s-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, Octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, iso (meth) acrylate Cutyl, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, tridecyl (meth) acrylate , Tetradecyl (meth) acrylate, and the like. Among these, (meth) acrylic acid alkyl ester having 4 to 12 carbon atoms in the alkyl group is suitable, and in particular, n-butyl acrylate can be suitably used.

The (meth) acrylic acid C _2-14 alkyl ester (a) may be used alone or in combination of two or more.

In the present invention, the (meth) acrylic acid C _2-14 alkyl ester (a) is preferably used as a monomer main component for constituting the acrylic polymer (X). The proportion of the (meth) acrylic acid C _2-14 alkyl ester (a) is preferably 50 to 75% by weight, more preferably 55 to 75% by weight, based on the total amount of the monomer components.

  The cyano group-containing monomer (b) is not particularly limited as long as it is a monomer having a cyano group, and examples thereof include acrylonitrile and methacrylonitrile. As the cyano group-containing monomer (b), acrylonitrile can be suitably used. In addition, you may use a cyano group containing monomer (b) individually or in combination of 2 or more types.

  In the present invention, it is preferable to use a cyano group-containing monomer (b) in order to improve heat resistance. Therefore, the proportion of the cyano group-containing monomer (b) is preferably 20 to 45% by weight, more preferably 24 to 40% by weight, based on the total amount of the monomer components. When the proportion of the cyano group-containing monomer (b) is less than 20% by weight based on the total amount of the monomer components, the heat resistance is poor, whereas when it is more than 45% by weight, flexibility may be lacking.

  The carboxyl group-containing monomer (c) is not particularly limited as long as it is a monomer having a carboxyl group. For example, (meth) acrylic acid [acrylic acid and / or methacrylic acid], itaconic acid, maleic acid, fumaric acid, Examples include crotonic acid. In addition, acid anhydrides of these carboxyl group-containing monomers (for example, acid anhydride group-containing monomers such as maleic anhydride and itaconic anhydride) can also be used as the carboxyl group-containing monomer. As the carboxyl group-containing monomer (c), it is preferable to use acrylic acid, methacrylic acid, and itaconic acid. In addition, you may use a carboxyl group-containing monomer (c) individually or in combination of 2 or more types.

  In the present invention, it is preferable to use a carboxyl group-containing monomer (c) in order to improve heat resistance and adhesiveness. Therefore, the ratio of the carboxyl group-containing monomer (c) is preferably 0.1 to 7% by weight, more preferably 0.5 to 6% by weight, based on the total amount of the monomer components. When the proportion of the carboxyl group-containing monomer (c) is more than 7% by weight based on the total amount of the monomer components, the flexibility is insufficient, and when it is less than 0.1% by weight, the effect of addition may not be obtained.

As the monomer component constituting the acrylic polymer (X), in addition to the (meth) acrylic acid C _2-14 alkyl ester (a), the cyano group-containing monomer (b) and the carboxyl group-containing monomer (c), A monomer component (copolymerizable monomer) may be used. Examples of such copolymerizable monomers include methyl (meth) acrylate; pentadecyl (meth) acrylate, hexadecyl (meth) acrylate, heptadecyl (meth) acrylate, octadecyl (meth) acrylate, (meth) (Meth) acrylic acid C _15-20 alkyl ester such as nonadecyl acrylate, eicosyl (meth) acrylate; (meth) acrylic acid cycloalkyl ester [(meth) acrylic acid cyclohexyl, etc.], (meth) acrylic acid isobornyl, etc. Non-aromatic ring-containing (meth) acrylic acid ester; (meth) acrylic acid aryl ester [(meth) acrylic acid phenyl etc.], (meth) acrylic acid aryloxyalkyl ester [(meth) acrylic acid phenoxyethyl etc.] And (meth) acrylic acid arylalkyl es Aromatic ring-containing (meth) acrylic acid ester such as ru [(meth) acrylic acid benzyl ester]; Epoxy group-containing acrylic monomer such as (meth) acrylic acid glycidyl, (meth) acrylic acid methyl glycidyl; vinyl acetate, Vinyl ester monomers such as vinyl propionate; Styrene monomers such as styrene and α-methylstyrene; Hydroxyl groups such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate Monomer; (meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl; (meth) acrylic acid aminoethyl, (meth) acrylic acid N, N-dimethylaminoethyl, T-Butyl (meth) acrylate (Meth) acrylic acid aminoalkyl monomers such as aminoethyl; (N-substituted) such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hydroxy (meth) acrylamide, etc. ) Amide monomers; Olefin monomers such as ethylene, propylene, isoprene and butadiene; Vinyl ether monomers such as methyl vinyl ether.

  As copolymerizable monomers, hexanediol di (meth) acrylate, butanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (Meth) acrylate, pentaerythritol di (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester Polyfunctional monomers such as acrylate, urethane acrylate and divinylbenzene can also be used.

  The acrylic polymer (X) can be prepared by a known or conventional polymerization method (for example, a solution polymerization method, an emulsion polymerization method, a suspension polymerization method, a bulk polymerization method, or a polymerization method by ultraviolet irradiation).

  The polymerization initiator, chain transfer agent, emulsifier and the like used in the polymerization of the acrylic polymer (X) are not particularly limited, and can be appropriately selected from known or commonly used ones. More specifically, examples of the polymerization initiator include 2,2′-azobisisobutyronitrile, 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2,2 ′. -Azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2-methylbutyronitrile), 1,1'-azobis (cyclohexane-1-carbonitrile), 2,2'-azobis (2 , 4,4-trimethylpentane), dimethyl-2,2'-azobis (2-methylpropionate), 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazoline-2 -Yl] propane} dihydrochloride and other azo polymerization initiators; benzoyl peroxide, t-butyl hydroperoxide, di-t-butyl peroxide, t-butyl peroxyben Peroxide polymerization such as zoate, dicumyl peroxide, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, 1,1-bis (t-butylperoxy) cyclododecane An initiator etc. are mentioned. A polymerization initiator can be used individually or in combination of 2 or more types. The usage-amount of a polymerization initiator can be suitably selected from the range of a normal usage-amount.

  Examples of the chain transfer agent include 2-mercaptoethanol, lauryl mercaptan, glycidyl mercaptan, mercaptoacetic acid, 2-ethylhexyl thioglycolate, 2,3-dimethylcapto-1-propanol, and α-methylstyrene dimer. It is done. As an emulsifier, anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, polyoxyethylene alkyl phenyl ether ammonium sulfate, sodium polyoxyethylene alkyl phenyl ether sulfate; polyoxyethylene Nonionic emulsifiers such as alkyl ethers and polyoxyethylene alkylphenyl ethers may be mentioned.

  In solution polymerization, various common solvents can be used. Examples of such solvents include esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane and methylcyclohexane Organic solvents such as ketones such as methyl ethyl ketone and methyl isobutyl ketone. A solvent can be used individually or in combination of 2 or more types.

  Although it does not restrict | limit especially as a weight average molecular weight of acrylic polymer (X), For example, it can select suitably from the range of 200,000-1,600,000 (preferably 300,000-1,400,000). The weight average molecular weight of the acrylic polymer (X) can be controlled by the monomer concentration, the monomer dropping rate, etc., in addition to the type and amount of polymerization initiator and chain transfer agent, the temperature and time during polymerization. The weight average molecular weight of the acrylic polymer (X) can be measured, for example, by gel permeation chromatography (GPC), and the measurement conditions are not particularly limited, and are appropriately selected from known measurement conditions. be able to.

[Phenolic resin (Y)]
The phenol resin (Y) is not particularly limited as long as it is a phenol resin, and is appropriately selected from a resol type phenol resin, a novolac type phenol resin, various modified phenol resins (for example, an alkyl modified phenol resin, etc.), and the like. Can be used. Among them, in a blended system containing the acrylic polymer of the present invention as a main ingredient and hexamethylenetetramine as an essential component, heat resistance tends to be more advantageous when using a novolak type phenol resin than a resol type phenol resin. For this reason, when higher heat resistance is required, a novolac type phenol resin is preferable. In addition, a phenol resin (Y) can be used individually or in combination of 2 or more types.

  As the phenol resin (Y), a commercially available phenol resin can be used. Examples of the resol type phenol resin include a trade name “Sumilite Resin PR-51283” (manufactured by Sumitomo Bakelite Co., Ltd.), As the novolak-type phenol resin, for example, “Tamanor 758” (manufactured by Arakawa Chemical Industries, Ltd.) can be used.

  The said phenol resin (Y) is used in order to provide thermosetting and heat resistance. The blending ratio of the phenol resin (Y) is 1 to 60 parts by weight, preferably 10 to 55 parts by weight, more preferably 15 to 55 parts by weight, based on 100 parts by weight of the acrylic polymer (X). More preferably, it is 21-55 weight part, Most preferably, it is 25-52 weight part. If the proportion of the phenol resin (Y) is less than 1 part by weight relative to 100 parts by weight of the acrylic polymer (X), the thermosetting property and heat resistance (strength of the adhesive layer) are insufficient, while 60 parts by weight. If it is more, the reaction is too fast and the fluidity before curing is insufficient, so that it cannot sufficiently adhere to the surface of the adherend, causing a decrease in adhesive strength and heat resistance.

[Hexamethylenetetramine (Z)]
The hexamethylenetetramine (Z) is used for imparting thermosetting and heat resistance in combination with the phenol resin (Y). The blending ratio of hexamethylenetetramine (Z) is 1 to 25 parts by weight, preferably 5 to 20 parts by weight with respect to 100 parts by weight of the acrylic polymer (X). When the ratio of hexamethylenetetramine (Z) is less than 1 part by weight with respect to 100 parts by weight of the acrylic polymer (X), the thermosetting property and the heat resistance are insufficient. descend.

  Commercially available products can be used as the hexamethylenetetramine (Z), and for example, the trade name “Noxeller H” (manufactured by Ouchi Shinsei Chemical Industry Co., Ltd.) can be used.

[Thermosetting adhesive composition]
The thermosetting adhesive composition of the present invention contains acrylic polymer (X), phenol resin (Y) and hexamethylenetetramine (Z) as essential components. The ratio of acrylic polymer (X), phenol resin (Y), and hexamethylenetetramine (Z) in the thermosetting adhesive composition is as follows. Phenolic resin (X): 100 parts by weight of acrylic polymer (X) The proportion of Y) is 1 to 60 parts by weight (preferably 15 to 55 parts by weight), and the proportion of hexamethylenetetramine (Z) is 1 to 25 parts by weight (preferably 5 to 20 parts by weight).

  In the thermosetting adhesive composition of the present invention, the ratio of the mass of the phenol resin (Y) divided by the mass of hexamethylenetetramine (Z) [phenol resin (Y) / hexamethylenetetramine (Z)] (weight ratio) Is preferably 1.5 to 40, more preferably 2 to 20. If the ratio is less than 1.5, the adhesive strength may be reduced, and if it exceeds 40, the thermosetting property may be insufficient.

  In the thermosetting adhesive composition, in addition to the acrylic polymer (X), the phenol resin (Y), and the hexamethylenetetramine (Z), an anti-aging agent, a filler, a colorant (pigment) may be used as necessary. And dyes), UV absorbers, antioxidants, crosslinking agents, tackifiers, plasticizers, softeners, surfactants, antistatic agents and the like, as long as they do not impair the characteristics of the present invention. It may be included.

  The thermosetting adhesive composition includes an acrylic polymer (X), a phenol resin (Y), hexamethylenetetramine (Z), and various additives (anti-aging agent, filler, pigment, etc.) as necessary. And can be prepared by mixing.

The storage elastic modulus at 250 ° C. after curing the thermosetting adhesive composition or the thermosetting adhesive layer formed by the thermosetting adhesive composition at 150 ° C. for 3 hours is 1 It is preferably 0.0 × 10 ⁵ Pa or more, more preferably 1.0 × 10 ⁶ Pa or more. There exists a tendency for heat resistance to fall that the storage elastic modulus in the said 250 degreeC is less than 1.0 * 10 < ⁵ > Pa.

  The above storage elastic modulus was measured using a viscoelasticity measuring device having an apparatus name “ARES” (Rheometrics), using a film jig, a heating rate of 5 ° C./min, a frequency of 1 Hz, and a strain. : It can be measured under a measurement condition of 0.1%.

  In addition, acrylic polymer (X), phenol resin (Y), and hexamethylenetetramine (Z) can be used in the state of a solution or a dispersion liquid. When the acrylic polymer (X) is used in a solution state, the solvent is not particularly limited. For example, the solvent is appropriately selected from the exemplified solvents as the solvent used when preparing the acrylic polymer (X) by solution polymerization. can do. In addition, when the phenol resin (Y) or hexamethylenetetramine (Z) is used in a solution state, the solvent is not particularly limited. For example, monohydric alcohols such as methanol, ethanol, propanol, isopropanol, and butanol; ethylene glycol Polyhydric alcohols such as; ketones; acetate esters; ethers and the like can be used.

[Thermosetting adhesive tape or sheet]
The thermosetting adhesive tape or sheet of the present invention is a thermosetting adhesive tape or sheet having at least a thermosetting adhesive layer formed from the above thermosetting adhesive composition. As long as the thermosetting adhesive tape or sheet has a thermosetting adhesive layer by the thermosetting adhesive composition, the thermosetting adhesive tape or sheet may or may not have a substrate. Good. Accordingly, as the thermosetting adhesive tape or sheet, (1) a thermosetting adhesive tape or sheet (baseless thermosetting adhesive tape or sheet) having a configuration formed only from the thermosetting adhesive layer, (2 ) A thermosetting adhesive tape or sheet (a thermosetting adhesive tape or sheet with a substrate) having a structure in which a thermosetting adhesive layer is formed on at least one surface (both surfaces or one surface) of the substrate. As the thermosetting adhesive tape or sheet, the thermosetting adhesive tape or sheet having the configuration (1) (that is, the baseless thermosetting adhesive tape or sheet having a configuration formed only from the thermosetting adhesive layer) ) Is preferred.

  When the thermosetting adhesive tape or sheet is a thermosetting adhesive tape or sheet with a substrate, a thermosetting adhesive layer is formed on the at least one surface of the substrate by the thermosetting adhesive composition. The other surface of the substrate may be formed with a thermosetting adhesive layer other than the above-mentioned thermosetting adhesive layer in addition to the known pressure-sensitive adhesive layer and adhesive layer.

  Moreover, the thermosetting adhesive tape or sheet may be formed in the form wound by roll shape, and may be formed in the form by which the sheet | seat was laminated | stacked. That is, the thermosetting adhesive tape or sheet of the present invention can have a form such as a sheet form or a tape form. In addition, when the thermosetting adhesive tape or sheet has a form wound in a roll shape, for example, a thermosetting adhesive layer is formed on the back side of the separator (release liner) or the substrate. You may have the form wound by the roll shape in the state protected by the peeling process layer.

(Thermosetting adhesive layer)
The thermosetting adhesive layer is formed of the thermosetting adhesive composition as described above. Therefore, the thermosetting adhesive layer has a stable storage property at room temperature, and further, when heated, a curing reaction occurs, the adhesive strength increases, and the heat resistance is strong and excellent. It is a thermosetting adhesive layer having an adhesive property that can be adhered by the above.

  The thickness of the thermosetting adhesive layer is, for example, preferably from 5 to 100 μm, more preferably from 10 to 50 μm, still more preferably from 20 to 40 μm, from the viewpoints of adhesiveness and workability. The thermosetting adhesive layer may have either a single layer or a laminate.

  The above thermosetting adhesive layer may be protected by a release liner. Such a release liner is not particularly limited, and can be appropriately selected from known release liners.

  When the thermosetting adhesive tape or sheet has a substrate, the substrate is not particularly limited, and for example, a paper-based substrate such as paper; a fiber-based substrate such as cloth, nonwoven fabric, and net; Metal base materials such as metal foil and metal plate; various resins (olefin resin, polyester resin, polyvinyl chloride resin, vinyl acetate resin, amide resin, polyimide resin, polyether ether ketone (PEEK), Polyphenylene sulfide (PPS) etc.) plastic base materials such as films and sheets; rubber base materials such as rubber sheets; foams such as foam sheets and laminates thereof (particularly plastic base materials and other groups) An appropriate thin leaf body such as a laminate with a material or a laminate of plastic films (or sheets) can be used.

  It does not restrict | limit especially as thickness of the said base material, For example, 10-500 micrometers is preferable, More preferably, it is 12-200 micrometers, More preferably, it is 15-100 micrometers. In addition, the base material may have a single layer form or may have a multiple layer form. Further, the substrate may be subjected to various treatments such as back treatment, antistatic treatment, and undercoating treatment as necessary.

  The thermosetting adhesive tape or sheet may have other layers (for example, an intermediate layer, an undercoat layer, etc.) as long as the effects of the present invention are not impaired.

  The thermosetting adhesive tape or sheet of the present invention can be produced according to a usual method for producing an adhesive tape or sheet. For example, when the thermosetting adhesive tape or sheet is a substrate-less thermosetting adhesive tape or sheet, the thermosetting adhesive composition solution is dried on the release surface of the release liner with a predetermined thickness after drying. It can be produced by a method of applying to a thickness and drying.

  In applying the thermosetting adhesive composition solution, a conventional coater (for example, gravure roll coater, reverse roll coater, kiss roll coater, dip roll coater, bar coater, knife coater, spray roll coater, etc.) is used. be able to.

  The thermosetting adhesive tape or sheet of the present invention hardly undergoes a curing reaction at room temperature and can be stored for a long time at room temperature. Further, it can be cured by heating and firmly adhered to the adherend. Flexible printed circuit boards (FPCs) often go through a high-temperature reflow process before being incorporated into the final product, and the thermosetting adhesive tape or sheet used will float and swell after the reflow process. It is required not to. Furthermore, from the viewpoint of reliability, there is a demand for no floating or swelling in heat resistance tests after wet heat under more severe conditions (good heat resistance after wet heat). The thermosetting adhesive tape or sheet of the present invention can exhibit performance as a thermosetting adhesive in a well-balanced manner, and also exhibits excellent heat resistance (particularly heat resistance after wet heat) after thermosetting. be able to.

  Therefore, the thermosetting adhesive tape or sheet of the present invention can be stored for a long time at room temperature, and can be bonded with excellent heat resistance and good adhesiveness. Therefore, the thermosetting adhesive tape or sheet of the present invention is preferably used in applications that require strong and excellent heat resistance by heating while requiring long-term storage at room temperature. it can. Specifically, the thermosetting adhesive tape or sheet of the present invention can be suitably used for bonding on a flexible printed circuit board (FPC). Note that the adhesion of the FPC means the adhesion when the FPC is manufactured as described above or the adhesion when the FPC is bonded to the reinforcing plate. At the time of bonding, the thermosetting adhesive tape or sheet of the present invention is bonded to the FPC to form the above thermosetting adhesive layer on the FPC (that is, the thermosetting adhesive of the present invention). As an FPC having a thermosetting adhesive layer of the composition).

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In addition, below, the compounding quantity of a phenol resin, hexamethylenetetramine, and an epoxy resin was shown by the weight part on the non-volatile matter basis. Tables 1 and 2 show the monomer composition (weight ratio) of the acrylic polymer in the following examples and comparative examples, and the acrylic polymer, phenol resin, and hexax in the thermosetting adhesive composition solution. The blending amounts (parts by weight) of methylenetetramine and epoxy resin are shown.

Example 1
In a reactor equipped with a condenser, a nitrogen inlet, a thermometer, and a stirrer, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydro Chloride (trade name “VA-060”, manufactured by Wako Pure Chemical Industries, Ltd.) (initiator) 0.279 g and ion-exchanged water 100 g were added, and the mixture was stirred for 1 hour while introducing nitrogen gas. This was kept at 60 ° C., where 72 parts by weight of butyl acrylate, 27 parts by weight of acrylonitrile, 1 part by weight of acrylic acid, 0.04 parts by weight of dodecanethiol (chain transfer agent) and sodium polyoxyethylene lauryl ether sulfate (emulsifier) 400 g of an emulsion obtained by adding 2 parts by weight to 41 parts by weight of ion-exchanged water (emulsion of monomer raw material) was gradually added dropwise over 3 hours to proceed the emulsion polymerization reaction. After completion of the dropwise addition of the monomer raw material emulsion, the mixture was further aged by maintaining the same temperature for 3 hours. The aqueous dispersion (emulsion) of the acrylic polymer thus polymerized was dried to obtain an acrylic polymer.

Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 72: 27: 1 (weight ratio)]: softened in an ethyl acetate solution in which 100 parts by weight was dissolved Trade name “Tamanor 758” (manufactured by Arakawa Chemical Industries, Ltd.) as a novolac type phenolic resin having a point of 80 to 85 ° C .: an ethyl acetate solution in which 40 parts by weight is dissolved, and a trade name “Noxeller H” ( (Ouchi Shinsei Chemical Co., Ltd.): A methanol solution in which 10 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution.
That is, the thermosetting adhesive composition solution contains 40 parts by weight of novolac phenolic resin and 10 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer.

  The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Example 2
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Softening point in an ethyl acetate solution in which 100 parts by weight was dissolved Trade name “Tamanor 758” (manufactured by Arakawa Chemical Industries, Ltd.) as a novolak type phenolic resin at 80 to 85 ° C .: Trade name “Noxeller H” as an ethyl acetate solution in which 10.1 parts by weight are dissolved and hexamethylenetetramine (Ouchi Shinsei Chemical Co., Ltd.): A methanol solution in which 4.7 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution. That is, the thermosetting adhesive composition solution contains 10.1 parts by weight of novolak type phenol resin and 4.7 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer. . In addition, the polymerization method of an acrylic polymer is the same as that of Example 1 (The following examples and comparative examples are also the same).
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Example 3
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Softening point in an ethyl acetate solution in which 100 parts by weight was dissolved Trade name “Tamanor 758” (manufactured by Arakawa Chemical Industries, Ltd.) as a novolak type phenolic resin at 80 to 85 ° C .: 22.5 parts by weight of an ethyl acetate solution and trade name “Noxeller H” as hexamethylenetetramine (Manufactured by Ouchi Shinsei Chemical Co., Ltd.): A methanol solution in which 3 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution. That is, in the thermosetting adhesive composition solution, 22.5 parts by weight of novolac-type phenol resin and 3 parts by weight of hexamethylenetetramine are contained with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Example 4
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Softening point in an ethyl acetate solution in which 100 parts by weight was dissolved Trade name “Tamanor 758” (manufactured by Arakawa Chemical Industries, Ltd.) as a novolak type phenolic resin at 80 to 85 ° C .: 22.5 parts by weight of an ethyl acetate solution and trade name “Noxeller H” as hexamethylenetetramine (Ouchi Shinsei Chemical Co., Ltd.): A methanol solution in which 9 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution. That is, the thermosetting adhesive composition solution contains 22.5 parts by weight of novolac-type phenol resin and 9 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Example 5
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Novolak type in 100 parts by weight of ethyl acetate solution Phenol resin (trade name “Tamanor 758”, manufactured by Arakawa Chemical Industries, Ltd.): 40 parts by weight of ethyl acetate solution and hexamethylenetetramine as trade name “Noxeller H” (Ouchi Shinsei Chemical Industry Co., Ltd.) Manufactured): A methanol solution in which 2 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution. That is, the thermosetting adhesive composition solution contains 40 parts by weight of novolac type phenol resin and 2 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Example 6
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Novolak type in 100 parts by weight of ethyl acetate solution Phenol resin (trade name “Tamanor 758”, manufactured by Arakawa Chemical Industries, Ltd.): 40 parts by weight of ethyl acetate solution and hexamethylenetetramine as trade name “Noxeller H” (Ouchi Shinsei Chemical Industry Co., Ltd.) Product): A methanol solution having 5 parts by weight dissolved therein was mixed and stirred to prepare a thermosetting adhesive composition solution. That is, the thermosetting adhesive composition solution contains 100 parts by weight of the acrylic polymer, 40 parts by weight of the novolac type phenol resin, and 5 parts by weight of hexamethylenetetramine.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Example 7
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Novolak type in 100 parts by weight of ethyl acetate solution Phenol resin (trade name “Tamanor 758”, manufactured by Arakawa Chemical Industries, Ltd.): 40 parts by weight of ethyl acetate solution and hexamethylenetetramine as trade name “Noxeller H” (Ouchi Shinsei Chemical Industry Co., Ltd.) Product): A methanol solution in which 16 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution. That is, the thermosetting adhesive composition solution contains 40 parts by weight of novolac type phenol resin and 16 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Example 8
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Novolak type in 100 parts by weight of ethyl acetate solution Phenol resin (trade name “Tamanor 758”, manufactured by Arakawa Chemical Industries, Ltd.): 50 parts by weight of ethyl acetate solution and hexamethylenetetramine as trade name “Noxeller H” (Ouchi Shinsei Chemical Industry Co., Ltd.) Product): A methanol solution in which 10 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution. That is, the thermosetting adhesive composition solution contains 50 parts by weight of novolac-type phenol resin and 10 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Example 9
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: 50 ° C. in an ethyl acetate solution in which 100 parts by weight was dissolved Product name “Sumilite Resin PR-51283” (manufactured by Sumitomo Bakelite Co., Ltd.): a methanol solution in which 40 parts by weight is dissolved, and hexamethylenetetramine As a trade name “NOXELLA H” (manufactured by Ouchi Shinsei Chemical Co., Ltd.): A methanol solution in which 5 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution. That is, the thermosetting adhesive composition solution contains 40 parts by weight of a resol type phenol resin and 5 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of an acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Comparative Example 1
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Softening point in an ethyl acetate solution in which 100 parts by weight was dissolved Trade name “Tamanor 758” (manufactured by Arakawa Chemical Industries, Ltd.) as a novolak type phenolic resin at 80 to 85 ° C .: Mixing and stirring an ethyl acetate solution in which 40 parts by weight is dissolved, and thermosetting adhesive composition A product solution was prepared.
That is, the thermosetting adhesive composition solution contains 40 parts by weight of a novolak type phenol resin with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Comparative Example 2
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Softening point in an ethyl acetate solution in which 100 parts by weight was dissolved Trade name “Tamanol 758” (manufactured by Arakawa Chemical Industries, Ltd.) as a novolac type phenolic resin at 80 to 85 ° C .: Ethyl acetate solution in which 40 parts by weight is dissolved, and trade name “Noxeller H” (large) as hexamethylenetetramine Inner Shinsei Chemical Co., Ltd.): A methanol solution in which 40 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution.
That is, the thermosetting adhesive composition solution contains 40 parts by weight of novolac-type phenol resin and 40 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Comparative Example 3
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Softening point in an ethyl acetate solution in which 100 parts by weight was dissolved Trade name “Tamanor 758” (manufactured by Arakawa Chemical Industries, Ltd.) as a novolac type phenol resin at 80 to 85 ° C .: Ethyl acetate solution in which 65 parts by weight is dissolved, and trade name “Noxeller H” (large) as hexamethylenetetramine Inner Shinsei Chemical Co., Ltd.): A methanol solution in which 10 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution.
That is, the thermosetting adhesive composition solution contains 65 parts by weight of novolac phenol resin and 10 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Comparative Example 4
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Softening point in an ethyl acetate solution in which 100 parts by weight was dissolved Trade name “Tamanol 758” (manufactured by Arakawa Chemical Industries, Ltd.) as a novolak type phenolic resin at 80 to 85 ° C .: Ethyl acetate solution in which 80 parts by weight was dissolved, and trade name “Noxeller H” (large) as hexamethylenetetramine Inner Shinsei Chemical Co., Ltd.): A methanol solution in which 10 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution.
That is, the thermosetting adhesive composition solution contains 80 parts by weight of novolac-type phenol resin and 10 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Comparative Example 5
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 64: 34: 2 (weight ratio)]: Softening point in an ethyl acetate solution in which 100 parts by weight was dissolved Trade name “Tamanol 758” (manufactured by Arakawa Chemical Industries, Ltd.) as a novolak type phenolic resin at 80 to 85 ° C .: Ethyl acetate solution in which 80 parts by weight was dissolved, and trade name “Noxeller H” (large) as hexamethylenetetramine Inner Shinsei Chemical Co., Ltd.): A methanol solution in which 20 parts by weight was dissolved was mixed and stirred to prepare a thermosetting adhesive composition solution.
That is, the thermosetting adhesive composition solution contains 80 parts by weight of novolac-type phenol resin and 20 parts by weight of hexamethylenetetramine with respect to 100 parts by weight of the acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

Comparative Example 6
Acrylic polymer [(monomer composition) butyl acrylate (BA) / acrylonitrile (AN) / acrylic acid (AA) = 67: 30: 3 (weight ratio)]: 50 ° C. in an ethyl acetate solution in which 100 parts by weight was dissolved As a carboxylic acid-based resol type phenolic resin having a liquid form, a trade name “Sumilite Resin PR-51283” (manufactured by Sumitomo Bakelite Co., Ltd.): a methanol solution in which 20 parts by weight is dissolved, and a softening point of 64 Product name “JER1001” (manufactured by Japan Epoxy Resins Co., Ltd.): Bisphenol A type epoxy resin having an epoxy equivalent of 450 to 500 at ℃: Mixing and stirring an ethyl acetate solution in which 20 parts by weight is dissolved, heat curing A mold adhesive composition solution was prepared.
That is, the thermosetting adhesive composition solution contains 20 parts by weight of a resol type phenol resin and 20 parts by weight of a bisphenol A type epoxy resin with respect to 100 parts by weight of an acrylic polymer.
The thermosetting adhesive composition solution is applied to the release layer surface of the release liner so that the thickness after drying is 25 μm, and is dried at 100 ° C. for 3 minutes. A curable adhesive sheet) was obtained.

(Evaluation)
For each thermosetting adhesive sheet obtained in Examples and Comparative Examples, the adhesive strength after curing of the thermosetting adhesive layer, heat resistance, and storage stability before curing, respectively, the following adhesive strength evaluation method, heat resistance Measured or evaluated by a method for evaluating the property and a method for evaluating the storage stability.

(1) Evaluation method of adhesive force About the thermosetting adhesive layer after curing in the thermosetting adhesive sheets obtained in Examples and Comparative Examples, the adhesive force (N / cm) at 23 ° C was evaluated by the following method. did.
A flexible printed circuit board (FPC; size: 5 cm × 8 cm, thickness: 0.2 mm) and a thermosetting adhesive sheet were laminated at 130 ° C. and then cut to 1 cm width (the thermosetting adhesive sheet is one side of the FPC) (Laminated on the entire surface (surface material: polyimide)). This was attached to a polyimide plate (PI; size: 5 cm × 5 cm, thickness: 0.13 mm), laminated at 130 ° C., and then thermocompression bonded at 160 ° C. and 1 MPa for 90 seconds. Furthermore, the specimen was prepared by curing at 150 ° C. for 3 hours.
About the said test body, 90 degree peel adhesive force (tensile speed: 50 mm / min, 23 degreeC) by the method of pulling the FPC side using apparatus brand name "TCM-1kNB" (made by Minebea Co., Ltd.) (N / cm).
The evaluation results are shown in the column of “Adhesive strength (N / cm) PI” in Tables 1 and 2.

  Moreover, in the said measurement, 90 degree peel adhesive force was similarly measured using the stainless steel board (SUS; size: 5 cm x 5 cm, thickness: 0.4 mm) instead of a polyimide board. The evaluation results are shown in the column of “Adhesive strength (N / cm) SUS” in Tables 1 and 2.

(2) Evaluation method of heat resistance The heat resistance of the thermosetting adhesive layer after curing in the thermosetting adhesive sheets obtained in Examples and Comparative Examples was evaluated by the following method.
A copper-clad laminate (CCL; polyimide / copper laminate, size: 5 cm × 8 cm, thickness: 45 μm) and a thermosetting adhesive sheet were laminated at 130 ° C. and then cut to 1 cm width (thermosetting adhesion) The sheet is laminated on the entire CCL polyimide surface). This was attached to a polyimide plate (PI; size: 5 cm × 5 cm, thickness: 0.13 mm), laminated at 130 ° C., and then thermocompression bonded at 160 ° C. and 1 MPa for 90 seconds. Furthermore, the specimen was prepared by curing at 150 ° C. for 3 hours.
The test specimen was allowed to stand for 24 hours under humidified conditions (temperature: 60 ° C., humidity: 90% RH), and then reflowed at a peak temperature of 270 ° C. in an infrared heating furnace (IR heating furnace). (The following), the thermosetting adhesive layer in the thermosetting adhesive sheet was lifted off, and the state of foaming was visually observed.
“○” indicates that the heat-curing adhesive layer was lifted off and no foaming was confirmed, and “△” indicates that only a small amount was lifted off at the end of the affixed portion, and floated on the thermosetting adhesive layer. The heat resistance was evaluated as “x” when peeling or foaming was confirmed. The evaluation results are shown in the column of “Heat resistance” in Tables 1 and 2.

(Reflow process)
For the reflow apparatus or apparatus, a heating furnace using infrared rays [maximum temperature or peak temperature is set to 270 ° C .; conveyor type far infrared ray / hot air heating device (manufactured by Noritake Co., Ltd.)] was used. The surface temperature of the test specimen is fixed to the test specimen surface with an adhesive tape (heat-resistant adhesive tape based on a polyimide film), and a temperature sensor [KEYENCE NR-250 (manufactured by Keyence Corporation)]. Was measured continuously. FIG. 1 shows an example of a temperature profile [vertical axis: temperature (° C.), horizontal axis: time (seconds)] of the heat treatment conditions in the reflow process. The time for the reflow process was 360 seconds.

(3) Preservation evaluation method (measurement method of gel fraction)
Each of the thermosetting adhesive sheets (thermosetting adhesive layer) obtained in Examples and Comparative Examples was peeled off from the release liner with a size of 5 cm × 5 cm, and porous tetrafluoro having pores with an average pore diameter of 0.2 μm After wrapping in an ethylene sheet (trade name “NTF1122”, manufactured by Nitto Denko Corporation), it is tied with a kite string, the weight at that time is measured, and this weight is defined as the weight before immersion. The weight before immersion is the total weight of the thermosetting adhesive layer, the tetrafluoroethylene sheet, and the kite string. Further, the total weight of the tetrafluoroethylene sheet and the kite string is also measured, and this weight is defined as the wrapping weight.
In addition, as the said thermosetting type adhesive sheet, the thermosetting type adhesive sheet immediately after manufacture and the thermosetting type adhesive sheet after preserve | saving for 7 days at 40 degreeC were used. In the following, the thermosetting adhesive layer collected from the thermosetting adhesive sheet immediately after production is referred to as “initial thermosetting adhesive layer”, heat collected from the thermosetting adhesive sheet after being stored at 40 ° C. for 7 days. The curable adhesive layer may be referred to as “heat-cured adhesive layer after heating”.
Next, the above thermosetting adhesive layer (the initial thermosetting adhesive layer, the thermosetting adhesive layer after heating) is wrapped with a tetrafluoroethylene sheet and bound with a string (hereinafter referred to as “sample”) Is placed in a 50 ml container filled with methyl ethyl ketone and allowed to stand at room temperature (23 ° C.) for 1 week (7 days). Thereafter, the sample (after methyl ethyl ketone treatment) is taken out from the container, transferred to an aluminum cup, dried in a dryer at 130 ° C. for 2 hours to remove methyl ethyl ketone, the weight is measured, and the weight is immersed in the weight. And
Then, the gel fraction is calculated from the following formula.
Gel fraction (% by weight) = (A−B) / (C−B) × 100 (1)
(In Formula (1), A is the weight after immersion, B is the weight of the bag, and C is the weight before immersion.)

(Evaluation method of storage stability)
For the thermosetting adhesive sheets obtained in Examples and Comparative Examples, the gel fraction of the initial thermosetting adhesive layer and after heating (after storage at 40 ° C. for 7 days) according to the method for measuring the gel fraction described above. The gel fraction of the thermosetting adhesive layer was measured.
Difference in gel fraction before and after storage (before and after heating) from gel fraction (wt%) of initial thermosetting adhesive layer and gel fraction (wt%) of thermosetting adhesive layer after heating (gel) (Fractional difference) was calculated from the following equation. The difference in gel fraction is shown in the column of “Preservability” in Tables 1 and 2.
Gel fraction difference (points) = ED (2)
(In Formula (2), D is the gel fraction (% by weight) of the initial thermosetting adhesive layer, and E is the gel fraction (% by weight) of the thermosetting adhesive layer after heating.)

  As is clear from Tables 1 and 2, the thermosetting adhesive sheet of the present invention had good storage stability, excellent adhesiveness, and heat resistance. On the other hand, when the amount of hexamethylenetetramine is not appropriate (Comparative Examples 1 and 2) or when the proportion of the phenol resin is too large (Comparative Examples 3 to 5), the adhesive strength and heat resistance are insufficient, and an epoxy resin is used. When it was (Comparative Example 6), the storage stability was lowered.

FIG. 1 is a graph showing an example of a temperature profile of heat treatment conditions in a reflow process in the heat resistance evaluation method.

Claims (3)

Containing 1-60 parts by weight of phenol resin (Y) and 1-25 parts by weight of hexamethylenetetramine (Z) with respect to 100 parts by weight of the acrylic polymer (X) ,
The acrylic polymer (X) is essentially composed of (meth) acrylic acid alkyl ester (a), cyano group-containing monomer (b), and carboxyl group-containing monomer (c) whose alkyl group has 2 to 14 carbon atoms. Composed as a monomer component,
The monomer component constituting the acrylic polymer (X) is 50 to 75% by weight of (meth) acrylic acid alkyl ester (a) having 2 to 14 carbon atoms of the alkyl group, based on the total amount of the monomer component. A thermosetting adhesive composition comprising 20 to 45% by weight of the cyano group-containing monomer (b) and 0.1 to 7% by weight of the carboxyl group-containing monomer (c) . A thermosetting adhesive tape or sheet having at least a thermosetting adhesive layer formed by the thermosetting adhesive composition according to claim 1 . The flexible circuit board which has at least the thermosetting type adhesive bond layer formed with the thermosetting type adhesive composition of Claim 1 .

Images