JP6166605B2 - Adhesive composition and adhesive sheet - Google Patents

Description

  The present invention relates to an adhesive composition used for an adhesive and the like, and an adhesive sheet using the composition.

  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, they are composed of elastomers / phenol resins / phenolic resin crosslinking agents. An adhesive is known (see Patent Document 1).

JP 2010-65078 A

  Depending on the application, the adhesive may be colored by adding a colorant for the purpose of improving visibility. However, when a colorant is contained, the adhesive strength may be reduced. Therefore, an object of the present invention is to provide an adhesive composition and an adhesive sheet that have both visibility and adhesive strength.

  The adhesive composition according to the present invention contains an acrylic polymer, a phenol resin, an epoxy resin, and a colorant, and contains 10 parts by weight or less of the colorant with respect to 100 parts by weight of the acrylic polymer.

  In the adhesive composition according to the present invention, it is preferable to contain 5 to 20 parts by weight of the resol-type phenol resin with respect to 100 parts by weight of the acrylic polymer.

  The adhesive composition according to the present invention preferably contains 5 to 20 parts by weight of the epoxy resin with respect to 100 parts by weight of the acrylic polymer.

  In the adhesive composition according to the present invention, the colorant is preferably a dye or a pigment.

  The adhesive sheet according to the present invention is formed of any one of the above adhesive compositions.

  The adhesive composition according to the present invention can provide an adhesive composition and an adhesive sheet having both visibility and adhesive strength.

  Hereinafter, the present invention will be specifically described.

  The adhesive composition according to the present invention contains an acrylic polymer, a phenol resin, an epoxy resin, and a colorant.

  In the present specification, “A to B” indicating a range means that the range is A or more and B or less, and various physical properties mentioned in the present specification are in Examples described later unless otherwise specified. The value measured by the described method is meant.

  In addition, the “main component” in the present specification means a component having the highest content ratio on a weight basis in the composition, and usually means 50 to 100 weight. Furthermore, in the present specification, the “adhesive sheet” includes a tape-like structure, that is, an “adhesive tape”.

[Acrylic polymer]
The acrylic polymer is not particularly limited as long as it is a polymer composed (or formed) with an acrylic monomer as an essential monomer component (monomer component), but as the monomer component, (meth) acrylic acid C ₂₋ Preferably, ₁₄ alkyl ester (a) and cyano group-containing monomer (b) are 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 85% by weight, cyano group-containing monomer (b) is 10 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.

The (meth) acrylic acid C _2-14 alkyl ester (a) is not particularly limited as long as it is a (meth) acrylic acid alkyl ester having a linear or branched alkyl group having 2 to 14 carbon atoms. . For example, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, s-butyl (meth) acrylate, (meth ) T-butyl acrylate, pentyl (meth) acrylate, isopentyl (meth) acrylate, hexyl (meth) acrylate, heptyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate , Isomethyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, decyl (meth) acrylate, isodecyl (meth) acrylate, undecyl (meth) acrylate, dodecyl (meth) acrylate, (Meth) acrylic acid tridecyl, (meth) acrylic acid tetradecyl, etc. It is. 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.

The (meth) acrylic acid C _2-14 alkyl ester (a) is preferably used as a main monomer component constituting the acrylic polymer. The proportion of the (meth) acrylic acid C _2-14 alkyl ester (a) is preferably 50 to 85% by weight, more preferably 60 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, and acrylonitrile can be preferably used. The cyano group-containing monomer (b) may be used alone or in combination of two or more.

  In the acrylic polymer, it is preferable to use a cyano group-containing monomer (b) in order to improve heat resistance and adhesiveness (flexibility). Therefore, the proportion of the cyano group-containing monomer (b) is preferably 10 to 45% by weight, more preferably 20 to 35% by weight, based on the total amount of the monomer components. When the ratio of the cyano group-containing monomer (b) is within the above range, the heat resistance and flexibility are more excellent.

  The carboxyl group-containing monomer (c) is not particularly limited as long as it is a monomer having a carboxyl group, and examples thereof include (meth) acrylic acid, itaconic acid, maleic acid, fumaric acid, and 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. The carboxyl group-containing monomer (c) may be used alone or in combination of two or more.

  In the acrylic polymer, a carboxyl group-containing monomer (c) is preferably used 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 ratio of the carboxyl group-containing monomer (c) is within the above range, the flexibility is more excellent.

As monomer components constituting the acrylic polymer, in addition to (meth) acrylic acid C _2-14 alkyl ester (a), cyano group-containing monomer (b) and carboxyl group-containing monomer (c), other monomer components ( Copolymerizable monomers) 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 esters such as nonadecyl acrylate and eicosyl (meth) acrylate; (meth) acrylic acid cycloalkyl esters [(meth) acrylic acid cyclohexyl, etc.], (meth) acrylic acid isobornyl, etc. Non-aromatic ring-containing (meth) acrylic acid ester; (meth) acrylic acid aryl ester [phenyl (meth) acrylate etc.], (meth) acrylic acid aryloxyalkyl ester [(meth) acrylic acid phenoxyethyl etc.] And (meth) acrylic acid arylalkyl ester [ (Meth) acrylic acid benzyl ester] and other aromatic ring-containing (meth) acrylic acid esters; glycidyl (meth) acrylate and epoxy group-containing acrylic monomers such as methyl glycidyl (meth) acrylate; vinyl acetate and vinyl propionate Vinyl ester monomers such as styrene; styrene monomers such as styrene and α-methylstyrene; hydroxyl group-containing monomers such as hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate; (Meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl, (meth) acrylic acid ethoxyethyl; (meth) acrylic acid aminoethyl, (meth) acrylic acid N, N-dimethylaminoethyl, (meth) T-Butylamino acrylate (Meth) acrylic aminoalkyl monomers such as ethyl; (N-substituted) such as (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylamide, N-hydroxy (meth) acrylamide 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 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, a polymerization method by ultraviolet irradiation, etc.).

  The polymerization initiator, chain transfer agent, emulsifier and the like used for the polymerization of the acrylic polymer 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 the emulsifier, anionic emulsifiers such as sodium lauryl sulfate, ammonium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium polyoxyethylene alkyl ether sulfate, ammonium polyoxyethylene alkyl phenyl ether 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 an acryl-type polymer, 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 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 can be measured by, for example, gel permeation chromatography (GPC), and the measurement conditions at that time are not particularly limited, and can be appropriately selected from known measurement conditions. .

[Phenolic resin]
The phenol resin is not particularly limited, and can be 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. Among these, a resol type phenol resin is preferable. In addition, a phenol resin can be used individually or in combination of 2 or more types.

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

  The said phenol resin is used in order to provide thermosetting and heat resistance. The blending ratio of the phenol resin is preferably 3 to 20 parts by weight, more preferably 4 to 18 parts by weight, and still more preferably 6 to 15 parts by weight with respect to 100 parts by weight of the acrylic polymer.

  When the ratio of the phenol resin is within the above range, it is excellent in thermosetting and heat resistance (strength of the adhesive layer).

[Epoxy resin]
As the epoxy resin, resins generally used in the field of adhesives can be used. For example, bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol S type epoxy resin, phenol novolac type epoxy resin, Glycidylamine type epoxy resin, cresol novolak type epoxy resin, biphenyl type epoxy resin, naphthalene type epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, heterocyclic epoxy resin, spiro ring-containing epoxy resin, halogenated epoxy resin, etc. Can be used. Of these, bisphenol A type epoxy resins and glycidyl amine type epoxy resins are preferably used. These can be used alone or in combination of two or more.

  As for the compounding quantity of an epoxy resin, 20 weight part or less is preferable with respect to 100 weight part of acrylic polymers, More preferably, it is 5-20 weight part. By setting it to 20 parts by weight or less, it is possible to suppress the generation of bubbles and a decrease in adhesiveness when press-curing.

[Colorant]
Although it does not specifically limit as said coloring agent, A conventionally well-known pigment or dye can be used. As pigments, zinc carbonate, zinc oxide, zinc sulfide, talc, carion, calcium carbonate, titanium oxide, silica, lithium fluoride, calcium fluoride, barium sulfate, alumina, zirconia, iron oxide, iron hydroxide, oxidation Inorganic pigments such as chrome, spinel type, chromic acid, chrome vermilion, bitumen, aluminum powder, bronze powder, calcium phosphate, phthalocyanine, azo, condensed azo, azo lake, anthraquinone Organic pigments such as those based on perylene, perinone, indigo and thioindigo, isoindolinone, azomethine azo, dioxazine, quinacridone, aniline black, triphenylmethane, and carbon black.

  Examples of the dye include azo dyes, anthraquinone, quinone phthalone, styryl, diphenylmethane, triphenylmethane, oxazine, triazine, xanthan, methane, azomethine, acridine, and diazine.

  From the viewpoint of visibility, it is preferable to use a pigment or dye that has a large color difference from the adherend. For example, when the adherend is a polyimide film, since the polyimide film is translucent yellow, it is preferable to use dark pigments or dyes such as black, blue, and green.

In particular, when coloring black, the black pigment carbon black is generally used. However, depending on the type of carbon black, there are those that lower the electrical resistance, and the volumetric efficiency of the tape containing the pigment is lowest. However, it is preferable to select the pigment and adjust the amount so that it is 1 × 10 ¹¹ (Ω · cm) or more.

[Adhesive composition]
In the adhesive composition, in addition to the acrylic polymer, phenol resin, epoxy resin, and colorant, an anti-aging agent, a filler, an ultraviolet absorber, an antioxidant, a cross-linking agent, and a tackifier are added as necessary. Further, known additives such as a plasticizer, a softener, a surfactant, and an antistatic agent may be contained. The adhesive composition can be prepared by mixing these components.

The storage elastic modulus at 250 ° C. after curing the adhesive composition or the adhesive layer formed by the adhesive composition at 150 ° C. for 3 hours is 1.0 × 10 ⁵ Pa or more. Preferably, it is 1.0 × 10 ⁶ Pa or more. When the storage elastic modulus at 250 ° C. is within the above range, the heat resistance is more excellent.

  The above storage elastic modulus is measured using a viscoelasticity measuring device having an apparatus name “ARES” (manufactured by 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%.

[Adhesive sheet]
The adhesive sheet which concerns on this invention is a sheet | seat which has the adhesive bond layer formed with the said adhesive composition. As long as the adhesive sheet has the adhesive layer, the adhesive sheet may have a base material or may not have a base material.

  In addition, when an adhesive sheet is an adhesive sheet with a base material, the adhesive layer by the said adhesive composition should just be formed in the at least one surface of a base material, and the other surface of a base material is well-known. In addition to the pressure-sensitive adhesive layer and the adhesive layer, an adhesive layer other than the adhesive layer may be formed.

  Moreover, the said adhesive sheet may be formed in the form wound by roll shape, may be formed in the form by which the sheet | seat was laminated | stacked, and can have forms, such as a sheet form and a tape form. .

  The adhesive 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 said adhesive sheet can be manufactured in accordance with the manufacturing method of a normal adhesive tape or a sheet | seat. For example, when the adhesive sheet is a substrate-less adhesive sheet, the adhesive composition solution is applied to the release surface of the release liner so that the thickness after drying becomes a predetermined thickness, and is dried. Can be produced.

  In applying the 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.) can be used. .

  In a preferred embodiment of the adhesive sheet, the adhesive sheet hardly cures at room temperature, can be stored for a long time at room temperature, and can be cured by heating to be firmly adhered to an adherend.

  In a preferred embodiment of the adhesive sheet, it is preferable from the viewpoints of temporary fixability, positioning, and the like that it exhibits tackiness at room temperature and can be easily temporarily bonded to an adherend. Specifically, as the adhesive force at the time of temporary adhesion, the adhesive force under the condition of a peeling speed of 100 mm / min peeling angle of 180 ° after standing for 15 minutes after pressing and reciprocating with a 2 kg roller against polyimide is 0. 5 to 8 N / 20 mm is preferable.

  Flexible printed circuit boards (FPCs) often go through a high-temperature reflow process before being incorporated into the final product, and the adhesive sheet used is required not to float or swell after passing through the reflow process. . Furthermore, from the viewpoint of reliability, there is a demand for no floating or swelling (good heat resistance after wet heat) in a heat resistance test after wet heat under more severe conditions. The adhesive sheet according to the present invention can exhibit performance as a thermosetting adhesive in a well-balanced manner, and can also exhibit excellent heat resistance (particularly heat resistance after wet heat) after thermosetting.

  Therefore, the adhesive sheet can be stored at room temperature for a long time, and can be bonded with excellent heat resistance and good adhesiveness. Therefore, the adhesive sheet of the present invention can be suitably used for applications that require strong and excellent heat resistance to be bonded by heating while requiring long-term storage at room temperature. Specifically, the adhesive sheet 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 the bonding, the above-mentioned adhesive layer can be formed on the FPC by bonding the adhesive sheet to the FPC.

(Adhesive layer)
As described above, the adhesive layer is formed of the adhesive composition. The adhesive layer has stable storage at room temperature, and further, by heating, a curing reaction occurs, the adhesive strength increases, and the adhesive layer can be firmly bonded with excellent heat resistance. A thermosetting adhesive layer having possible adhesiveness is preferable.

  The thickness of the 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 adhesive layer may have either a single layer or a laminate.

  The above 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.

(Base material)
When the adhesive sheet has a base material, the base material is not particularly limited. For example, a paper base material such as paper; a fiber base material such as cloth, nonwoven fabric, or net; a metal foil, a metal plate, or the like Various metal base materials: 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, laminates of plastic base materials and other base materials; An appropriate thin leaf body such as 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, undercoating treatment, and the like as necessary.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to the following examples and comparative examples. In the following description, “parts” and “%” are based on weight and are solid values converted unless otherwise specified.

[Example 1]
In a reactor equipped with a cooling tube, a nitrogen introduction tube, 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 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 part 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.

  The product name “Sumilite Resin PR-51283” (Sumitomo Bakelite Co., Ltd.) as a carboxylic acid-based resol type phenolic resin having a liquid form at 50 ° C. in an ethyl acetate solution in which 100 parts by weight of the acrylic polymer is dissolved. )) Methanol solution in which 7.5 parts by weight are dissolved, and trade name “JER1001” (manufactured by Japan Epoxy Resins Co., Ltd.) as a bisphenol A type epoxy resin having a softening point of 64 ° C. and an epoxy equivalent of 450 to 500. An ethyl acetate solution in which 5 parts by weight and 5 parts by weight of a black pigment (trade name “AT DN102 Black” manufactured by Dainichi Seika Kogyo Co., Ltd.) are dissolved is mixed and stirred to obtain a thermosetting adhesive composition solution. Was prepared.

  The thermosetting adhesive composition solution was applied to the release layer surface of the release liner so that the thickness after drying was 35 μm, and dried at 100 ° C. for 3 minutes to obtain a thermosetting adhesive sheet.

[Examples 2-14, Comparative Examples 1-5]
Except having changed into the component and preparation amount of Table 1, operation similar to Example 1 was performed and each thermosetting type adhesive sheet was produced.

〔Evaluation method〕
The following evaluation was performed about the adhesive sheet obtained by each Example and the comparative example.

(1) Visibility From the layer structure of polyimide film 25 μm / adhesive layer 25 μm / Cu wiring layer 35 μm / adhesive layer 15 μm / polyimide film 25 μm / adhesive layer 15 μm / Cu wiring layer 35 μm / adhesive layer 25 μm / polyimide film 25 μm. Model flexible printed circuit board (FPC, size: 5 cm × 8 cm, thickness: 0.2 mm, Cu wiring layer width 150 μm, gap between Cu wirings 100 μm) and adhesive sheets obtained in Examples and Comparative Examples Lamination was performed at 130 ° C. Turn the FPC over and confirm that the presence or absence of tape bonding can be clearly confirmed at a distance of 1 m from the other surface through the transparent part of the FPC (the gap between the Cu wiring layers). The case where it was not possible was set as x.

(2) Adhesive strength About the adhesive bond layer after hardening in the adhesive sheet obtained by the Example and the comparative example, the adhesive force (N / cm) in 23 degreeC was evaluated with the following method.

  A flexible printed circuit board (FPC; size: 5 cm × 8 cm, thickness: 0.2 mm) and an adhesive sheet were laminated at 130 ° C. and then cut to a width of 1 cm (the adhesive sheet was one side of the FPC (surface material: Laminated on the entire surface of polyimide). This was attached to a SUS304BA plate (size: 5 cm × 5 cm), laminated at 130 ° C., and then thermocompression bonded at 160 ° C. and 1 MPa for 90 seconds. Further, the specimen was cured at 150 ° C. for 3 hours.

  About the said test body, 90 degree | times peel adhesive force (tensile speed: 50 mm / min, 23 degreeC) by pulling the FPC side using apparatus brand name "TCM-1kNB" (made by Minebea Co., Ltd.) (N / cm).

  Moreover, after performing the reflow process on the test specimens after curing under the conditions described in paragraph 0081 described in JP 2010-65078 A, 90 ° peel adhesive strength (tensile) Speed: 50 mm / min, 23 ° C.) (N / cm).

  Further, after the reflow step, the test specimen was immersed in ion exchange water at 50 ° C. for 1 hour, and then the test specimen was pulled up from the ion exchange water, and the water droplets on the test specimen surface were wiped off with a waste cloth. The 90 ° peel adhesive strength (tensile speed: 50 mm / min, 23 ° C.) (N / cm) was measured by the same method as above.

(3) Heat resistance A copper-clad laminate (CCL; polyimide / copper laminate, size: 5 cm × 8 cm, thickness: 45 μm) and an adhesive sheet were laminated at 130 ° C. and then cut to a width of 1 cm (adhesive sheet) Is laminated on the entire polyimide surface of CCL). 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 2 MPa for 90 seconds. Further, the specimen was cured 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). (Conditions described in paragraph 0081 described in JP 2010-65078 A) and in each step, the adhesive layer in the adhesive sheet was lifted off and the foamed state was visually observed.

  “○” indicates that the adhesive layer is lifted off and no foaming is confirmed, “△” indicates that there is only a small amount of lifted off at the end of the applied part, and floating or foaming is confirmed on the adhesive layer. The heat resistance was evaluated with “×”.

(4) Gel fraction Porous tetrafluoroethylene sheet (trade name) having the pores having an average pore diameter of 0.2 μm, peeled off from the release liner at a size of 5 cm × 5 cm, respectively, in the adhesive sheets obtained in Examples and Comparative Examples After being wrapped in “NTF1122” (manufactured by Nitto Denko Corporation), it is bound 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 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 adhesive sheet, an adhesive sheet before curing and an adhesive sheet after curing were used.

  Next, the adhesive sheet wrapped with a tetrafluoroethylene sheet and bound with a kite string (hereinafter referred to as “sample”) is placed in a 50 ml container filled with methyl ethyl ketone, and then 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.)

Abbreviations in the table have the following meanings.
Colorant 1 Black pigment (trade name “AT DN102 Black”, manufactured by Dainichi Seika Kogyo Co., Ltd.)
Colorant 2 White pigment (trade name “NPE-1006”, manufactured by Dainichi Seika Kogyo Co., Ltd.)
Colorant 3 White pigment (trade name “R-2228”, manufactured by Dainichi Seika Kogyo Co., Ltd.)
Colorant 4 Blue dye (trade name “ORIPACS GN-28”, manufactured by Orient Chemical Industries)
Colorant 5 Green dye (trade name "OPLAS GREEN 533", manufactured by Orient Chemical Industries)
Colorant 6 Green dye (trade name “OIL GREEN 502”, manufactured by Orient Chemical Industries)
The present invention is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims, and the embodiments can be obtained by appropriately combining technical means disclosed in different embodiments. Is also included in the technical scope of the present invention.

Claims (5)

An adhesive composition for forming an adhesive sheet to be attached to polyimide,
Contains an acrylic polymer, a phenolic resin, an epoxy resin, and a colorant,
As the phenol resin, containing 5 to 20 parts by weight of a resol type phenol resin with respect to 100 parts by weight of the acrylic polymer,
Examples colorant, 1 0 parts by weight or less of the black color to said 100 parts by weight of the acrylic polymer contains a blue or green colorant, the adhesive composition. Per 100 parts by weight of the acrylic polymer adhesive composition of claim 1 Symbol placement containing 5 to 20 parts by weight of the epoxy resin. The adhesive composition according to claim 1 or 2 , wherein the colorant is a dye or a pigment. The adhesive composition according to claim 3, wherein the colorant is a dye. The adhesive sheet formed with the adhesive composition of any one of Claims 1-4.