Adhesive composition and laminated body having attached adhesive layer

Abstract

To provide: an adhesive composition capable of satisfying re-peelability, a redispersion property, and adhesiveness at the same time; and a laminated body having an attached adhesive layer using the same.SOLUTION: An adhesive composition contains a carboxy group-containing styrenic elastomer (A), a styrene-butadiene rubber (B), and an epoxy resin (C). The content of the styrene-butadiene rubber (B) is preferably 1 pt.mass or more and 50 pts.mass or less based on 100 pts.mass of the carboxy group-containing styrenic elastomer (A). The styrene content ratio of the styrene-butadiene rubber (B) is preferably 10 mass% or more and 70 mass% or less. The content of the carboxy group-containing styrenic elastomer (A) is preferably 30 pts.mass or more based on 100 pts.mass of the solid content of the adhesive composition. A laminated body having an attached adhesive layer includes a B-stage adhesive layer composed of the adhesive composition and a base material film in contact with at least one surface of the adhesive layer.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive composition and a laminate with an adhesive layer.

Background Art

[0002] In recent years, with the miniaturization and weight reduction of electronic devices, related products of printed wiring boards have diversified and their demand has been increasing. A printed wiring board is composed of a base material and copper foil, etc., and an adhesive composition is usually used when bonding them.

[0003] When manufacturing a printed wiring board, a laminate with an adhesive layer in which an adhesive layer made of an adhesive composition is formed on a desired base material such as a resin film is used. This laminate with an adhesive layer is bonded to a target adherend through the adhesive layer.

[0004] For example, Patent Document 1 discloses a technique related to a conductive adhesive sheet for a flexible printed wiring board (hereinafter sometimes referred to as "FPC"). Specifically, this conductive adhesive sheet for FPC has an adhesive layer laminated on one side of a support film, and the adhesive composition forming the adhesive layer contains a flame-retardant adhesive, a crosslinking agent, a conductive filler such as silver-coated copper, and an anti-blocking agent such as hydrophobic silica. Patent Document 1 describes that by setting specific amounts of the conductive filler and the anti-blocking agent, in a state where conductive adhesive sheets for FPC bonded to a metal reinforcing plate are stacked, the adhesive layer and the metal reinforcing plate can be easily peeled off without causing blocking.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the lamination of the adhesive layer of the laminate with an adhesive layer and the adherend, when misalignment occurs, the laminate with an adhesive layer is peeled off from the adherend together with the adhesive layer, the alignment is adjusted again, and the laminate with an adhesive layer is laminated with the adherend through the adhesive layer. Therefore, the adhesive composition constituting the adhesive layer is required to have re-peelability that can be peeled relatively easily even when laminated in a so-called B-stage state.

[0007] In order to achieve the above re-peelability, as described in Patent Document 1, it is conceivable to blend a filler into the adhesive composition. However, when a filler in an amount sufficient to ensure re-peelability is blended into the adhesive composition, precipitation of filler aggregates occurs due to a decrease in the redispersibility of the filler at the stage of the coating liquid before the formation of the adhesive layer, the coating property of the coating liquid of the adhesive composition deteriorates, and it becomes difficult to form a thin adhesive layer. In addition, since the content of the adhesive component in the adhesive composition decreases by the amount of the filler added, the adhesiveness also decreases. Therefore, there is a demand to suppress the amount of the filler used as much as possible, and if possible, to ensure re-peelability without using a filler.

[0008] The present invention has been made in view of such problems, and aims to provide an adhesive composition capable of simultaneously satisfying re-peelability, redispersibility, and adhesiveness, and a laminate with an adhesive layer using the same.

Means for Solving the Problems

[0009] The adhesive composition and the laminate with an adhesive layer according to the present invention are as follows.

[0010] [1] An adhesive composition containing a carboxy group-containing styrene-based elastomer (A), a styrene-butadiene rubber (B), and an epoxy resin (C). Adhesive composition. [2] The content of the styrene-butadiene rubber (B) is 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the carboxy group-containing styrene-based elastomer (A). The adhesive composition according to [1]. [3] The styrene content ratio of the styrene-butadiene rubber (B) is 10% by mass or more and 70% by mass or less. The adhesive composition according to [1] or [2]. [4] The content of the carboxy group-containing styrene-based elastomer (A) is 30 parts by mass or more with respect to 100 parts by mass of the solid content of the adhesive composition. The adhesive composition according to any one of [1] to [3]. [5] The content of the epoxy resin (C) is 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the carboxy group-containing styrene-based elastomer (A). The adhesive composition according to any one of [1] to [4]. [6] The epoxy resin (C) is a polyfunctional epoxy resin having an alicyclic skeleton and / or an epoxy resin having a polycyclic aromatic hydrocarbon skeleton. The adhesive composition according to any one of [1] to [5]. [7] The relative permittivity of the cured product of the adhesive composition measured at a frequency of 10 GHz is less than 3.0. The adhesive composition according to any one of [1] to [6]. [8] It is used for a flexible copper-clad laminate, a rigid copper-clad laminate, a flexible flat cable, or a sealing material. The adhesive composition according to any one of [1] to [7]. [9] It includes an adhesive layer composed of the adhesive composition according to any one of [1] to [7] and a base film in contact with at least one surface of the adhesive layer. The adhesive layer is in a B-stage state. A laminate with an adhesive layer.

Advantages of the Invention

[0011] The above adhesive composition has the above configuration. Therefore, the above adhesive composition can ensure re-peelability when laminating the B-stage adhesive layer without using a filler. Further, although the above adhesive composition can use a filler, since it can exhibit re-peelability basically without using a filler, even if a filler is used, re-peelability can be ensured by using a small amount of filler as an auxiliary.

[0012] The above adhesive composition does not need to use a filler to ensure re-peelability, and even if a filler is used, the amount of filler used can be small. Therefore, precipitation of filler aggregates can be reduced at the stage of the coating liquid before forming the adhesive layer. Therefore, in the above adhesive composition, a decrease in the redispersibility of the filler in the coating liquid is suppressed, and due to the improvement in the coatability of the coating liquid, it is easy to form a thin adhesive layer.

[0013] The above adhesive composition does not need to use a filler to ensure re-peelability, and even if a filler is used, the amount of filler used can be small. Therefore, it becomes easier to ensure an appropriate amount of the content of the adhesive component. Therefore, the above adhesive composition can suppress a decrease in adhesiveness.

[0014] Thus, according to the above adhesive composition, re-peelability, redispersibility, and adhesiveness can be satisfied simultaneously.

[0015] The above laminate with an adhesive layer includes a B-stage adhesive layer made of the above adhesive composition capable of simultaneously satisfying re-peelability, redispersibility, and adhesiveness. Therefore, even when misalignment occurs in the lamination of the adhesive layer and the adherend, the laminate can be peeled off relatively easily, the alignment can be adjusted again, and the laminate can be laminated with the adherend through the adhesive layer.

[0016] In addition, when manufacturing the above-mentioned laminate with an adhesive layer, the coating property of the coating liquid of the adhesive composition when forming the adhesive layer can be made good, so that the adhesive layer can be formed thinly and uniformly.

[0017] In addition, since the above-mentioned laminate with an adhesive layer does not achieve re-peelability only by the filler, it is easy to secure an appropriate amount of the adhesive component in the adhesive layer, and good adhesiveness can be ensured.

Embodiments for Carrying Out the Invention

[0018] Hereinafter, an embodiment of the present invention will be described, but the present invention is not limited thereto.

[0019] 1. Adhesive Composition The adhesive composition of this embodiment contains a carboxy group-containing styrene-based elastomer (A), a styrene-butadiene rubber (B), and an epoxy resin (C). The composition of the adhesive composition will be specifically described below.

[0020] 1.1 Carboxy Group-Containing Styrene-Based Elastomer (A) In the adhesive composition of this embodiment, the carboxy group-containing styrene-based elastomer (A) is an important adhesive component as the base of the adhesive composition. Specifically, the carboxy group-containing styrene-based elastomer (A) is a styrene-based elastomer containing a carboxy group. One or more carboxy group-containing styrene-based elastomers (A) can be used in combination.

[0021] Examples of the styrenic elastomer that constitutes the carboxy group-containing styrenic elastomer (A) include styrene-butadiene block copolymer (SB), styrene-ethylene propylene block copolymer (SEP), styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene-ethylene butylene-styrene block copolymer (SEBS), styrene-ethylene propylene-styrene block copolymer (SEPS), styrene-(ethylene-ethylene / propylene)-styrene block copolymer (SEEPS), and the like. Among these, from the viewpoint of adhesiveness and the like, styrene-ethylene butylene-styrene block copolymer (SEBS) is preferable.

[0022] In the carboxy group-containing styrenic elastomer (A), the carboxy group is one of the reactive functional groups capable of reacting with the epoxy group of the epoxy resin (C). As the carboxy group-containing styrenic elastomer (A), specifically, a modified styrenic elastomer in which a carboxy group is introduced into the above-described unmodified styrenic elastomer can be preferably used.

[0023] The carboxy group can be introduced by modifying the above-described unmodified styrenic elastomer with a modifier or the like. In this case, the modified styrenic elastomer can be said to be one obtained by modifying the above-described unmodified styrenic elastomer with a modifier having a carboxy group. Specifically, the modified styrenic elastomer can be a polymer having a portion derived from the above-described unmodified styrenic elastomer and a graft portion derived from the modifier, and preferably, it is an acid-modified styrenic elastomer obtained by graft-modifying the above-described unmodified styrenic elastomer with a modifier containing an α,β-unsaturated carboxylic acid or a derivative thereof.

[0024] The production of an acid-modified styrene-based elastomer by graft modification (graft polymerization) can be carried out by a known method, and a radical initiator may be used during production. As the method for producing the above acid-modified styrene-based elastomer, for example, a solution method in which the above-described unmodified desired styrene-based elastomer is heated and dissolved in a solvent such as toluene, and the above modifier and radical initiator are added, or a melt method in which the above-described unmodified desired styrene-based elastomer, modifier, and radical initiator are melt-kneaded using a Banbury mixer, kneader, extruder, etc. can be mentioned. The usage methods of the above-described unmodified desired styrene-based elastomer, modifier, and radical initiator are not particularly limited, and these may be added to the reaction system all at once or sequentially. Further, when producing the above acid-modified styrene-based elastomer, a modification aid for improving the graft efficiency by a modifier such as α,β-unsaturated carboxylic acid, a stabilizer for adjusting the resin stability, etc. can be further used.

[0025] The modifier can include α,β-unsaturated carboxylic acids and their derivatives. Examples of α,β-unsaturated carboxylic acids include maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, crotonic acid, aconitic acid, norbornenedicarboxylic acid, etc. Further, examples of derivatives of unsaturated carboxylic acids include acid anhydrides, acid halides, amides, imides, esters, etc. As the above modifier, itaconic anhydride, maleic anhydride, aconitic anhydride, and citraconic anhydride are preferable, and itaconic anhydride and maleic anhydride are particularly preferable in terms of adhesiveness. When using a modifier, it may be one or more selected from α,β-unsaturated carboxylic acids and their derivatives, and may be a combination of one or more α,β-unsaturated carboxylic acids and one or more of their derivatives, a combination of two or more α,β-unsaturated carboxylic acids, or a combination of two or more derivatives of α,β-unsaturated carboxylic acids, etc.

[0026] 1.2 Styrene-butadiene rubber (B) In the adhesive composition of the present embodiment, styrene-butadiene rubber (SBR) (B) exhibits peelability without using a filler, and even when a filler is used, it is an important component for exhibiting peelability to the extent of supplementally using a small amount of the filler.

[0027] The styrene-butadiene rubber (B) may be modified or unmodified. From the viewpoint of adhesive strength and the like, modified styrene-butadiene rubber (modified SBR) can be preferably used as the styrene-butadiene rubber (B), and unmodified styrene-butadiene can be preferably used from the viewpoint of cost reduction and the like. Further, one or more kinds of styrene-butadiene rubber (B) can be used in combination.

[0028] Specific examples of the modified styrene-butadiene rubber (modified SBR) include modified styrene-butadiene into which one or more functional groups containing heteroatoms such as a hydroxyl group, an epoxy group, an amino group, an alkoxy group, an alkoxysilyl group, a polyether group, and a carboxy group are introduced. Examples of the modification method include main-chain modification, single-end modification, and both-end modification, and are not particularly limited. Further, the production method of styrene-butadiene rubber is not particularly limited, and those synthesized by emulsion polymerization, solution polymerization, radical polymerization, anionic polymerization, cationic polymerization, etc. can be used.

[0029] From the viewpoint of ensuring peelability at the time of laminating the adhesive layer in the B-stage state, the styrene content ratio of the styrene-butadiene rubber (B) is preferably 10% by mass or more and 70% by mass or less, more preferably 15% by mass or more and 60% by mass or less, and even more preferably 20% by mass or more and 50% by mass or less. Note that the styrene content ratio (% by mass) of the styrene-butadiene rubber (B) = 100 × (mass of styrene units in the styrene-butadiene rubber (B)) / (mass of the styrene-butadiene rubber (B)). Further, the above-described lower limit value and upper limit value of the styrene content ratio can be arbitrarily combined.

[0030] 1.3 Epoxy resin (C) In the adhesive composition of the present embodiment, the epoxy resin (C) reacts with the carboxyl group of the carboxyl group-containing styrene-based elastomer (A), and is an important component for expressing the adhesiveness to the adherend and the heat resistance of the cured product of the adhesive composition.

[0031] Examples of the epoxy resin (C) include bisphenol A type epoxy resin, bisphenol F type epoxy resin, or hydrogenated products thereof; diglycidyl esters of orthophthalic acid, diglycidyl esters of isophthalic acid, diglycidyl esters of terephthalic acid, glycidyl esters of p-hydroxybenzoic acid, diglycidyl esters of tetrahydrophthalic acid, diglycidyl esters of succinic acid, diglycidyl esters of adipic acid, diglycidyl esters of sebacic acid, triglycidyl esters of trimellitic acid, and other glycidyl ester-based epoxy resins; ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, tetraphenyl glycidyl ether ethane, triphenyl glycidyl ether ethane, polyglycidyl ethers of sorbitol, polyglycidyl ethers of polyglycerol, and other glycidyl ether-based epoxy resins; glycidylamine-based epoxy resins such as triglycidyl isocyanurate and tetraglycidyl diaminodiphenylmethane; linear aliphatic epoxy resins such as epoxidized polybutadiene and epoxidized soybean oil, but are not limited thereto. Further, novolak type epoxy resins such as phenol novolak epoxy resin, o-cresol novolak epoxy resin, and bisphenol A novolak epoxy resin can also be used.

[0032] Furthermore, examples of the epoxy resin (C) include brominated bisphenol A type epoxy resin, phosphorus-containing epoxy resin, epoxy resin having a dicyclopentadiene skeleton, epoxy resin having a naphthalene skeleton, anthracene type epoxy resin, tertiary butyl catechol type epoxy resin, triphenylmethane type epoxy resin, tetraphenylethane type epoxy resin, biphenyl type epoxy resin, bisphenol S type epoxy resin, and the like. These epoxy resins (C) may be used alone or in combination of two or more.

[0033] As the epoxy resin (C), those having two or more epoxy groups in one molecule are preferable. This is because a crosslinked structure can be formed by the reaction with the carboxy group-containing styrene-based elastomer (A), and high heat resistance can be exhibited.

[0034] As the epoxy resin (C), from the viewpoints of ensuring simultaneous achievement of peelability, redispersibility, and adhesiveness, polyfunctional epoxy resins having an alicyclic skeleton, epoxy resins having a polycyclic aromatic hydrocarbon skeleton, and the like are preferable. These can be used alone or in combination of two or more. Among these, from the viewpoint of adhesive strength and the like, epoxy resins having a polycyclic aromatic hydrocarbon skeleton are more preferable, and among the epoxy resins having a polycyclic aromatic hydrocarbon skeleton, epoxy resins having a naphthalene skeleton are particularly preferable.

[0035] 1.4 Content of Components 1.4.1 Content of Carboxy Group-Containing Styrene-Based Elastomer (A) In the adhesive composition, the content of the carboxy group-containing styrene-based elastomer (A) can be 30 parts by mass or more with respect to 100 parts by mass of the solid content of the adhesive composition. According to this configuration, in both the case where no filler is used and the case where a small amount of filler is used as an auxiliary, the adhesive component can be sufficiently ensured, and the adhesiveness to the adherend can be made reliable. In the present disclosure, the "solid content" means the components excluding the solvent.

[0036] The content of the carboxy group-containing styrenic elastomer (A) is preferably 40 parts by mass or more, more preferably 50 parts by mass or more, and even more preferably 60 parts by mass or more with respect to 100 parts by mass of the solid content of the adhesive composition from the viewpoint of adhesiveness to the adherend and the like. Further, the content of the carboxy group-containing styrenic elastomer (A) is preferably 98 parts by mass or less, more preferably 96 parts by mass or less, and even more preferably 94 parts by mass or less with respect to 100 parts by mass of the solid content of the adhesive composition from the viewpoint of re-peelability and the like. Incidentally, the lower limit value and the upper limit value of the content of the carboxy group-containing styrenic elastomer (A) described above can be arbitrarily combined.

[0037] 1.4.2 Content of styrene-butadiene rubber (B) The content of the styrene-butadiene rubber (B) is preferably 1 part by mass or more and 50 parts by mass or less, more preferably 3 parts by mass or more and 20 parts by mass or less, and even more preferably 3 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the carboxy group-containing styrenic elastomer (A) from the viewpoints of re-peelability, redispersibility, adhesiveness, and the like. Incidentally, the lower limit value and the upper limit value of the styrene-butadiene rubber (B) described above can be arbitrarily combined.

[0038] 1.4.3 Content of epoxy resin (C) The content of the epoxy resin (C) is preferably 1 part by mass or more and 20 parts by mass or less, more preferably 1.5 parts by mass or more and 18 parts by mass or less, and even more preferably 2 parts by mass or more and 15 parts by mass or less with respect to 100 parts by mass of the carboxy group-containing styrenic elastomer (A) from the viewpoints of re-peelability, redispersibility, adhesiveness, and the like. Incidentally, the lower limit value and the upper limit value of the content of the epoxy resin (C) described above can be arbitrarily combined.

[0039] 1.5 Other components In addition to the carboxy group-containing styrenic elastomer (A), styrene-butadiene rubber (B), and epoxy resin (C) described above, the adhesive composition of the present embodiment can contain, for example, other thermoplastic resins other than the carboxy group-containing styrenic elastomer (A), tackifiers, flame retardants, curing agents, curing accelerators, coupling agents, heat stabilizers, inorganic fillers, leveling agents, defoaming agents, pigments, ultraviolet absorbers, lubricants, solvents, etc., to such an extent that they do not affect the functions of the adhesive composition.

[0040] Note that, in the adhesive composition of the present embodiment, by using styrene-butadiene rubber (B) together with the carboxy group-containing styrenic elastomer (A) and epoxy resin (C), it is possible to ensure peelability again without using a filler for ensuring peelability again. However, it does not require not using any filler at all for ensuring peelability again, and it is also possible to use a filler supplementarily. In the adhesive composition of the present embodiment, a formulation that does not use a filler for ensuring peelability again can enhance redispersibility and adhesiveness while ensuring peelability again by adding styrene-butadiene rubber (B). On the other hand, in the adhesive composition of the present embodiment, in a formulation using a filler, although redispersibility and adhesiveness are slightly reduced compared to a formulation not using a filler, peelability again can be enhanced more by the supplementarily added filler and styrene-butadiene rubber (B). Thus, whether or not to contain a filler that develops peelability again for the adhesive composition of the present embodiment can be selected in consideration of the balance of peelability again, redispersibility, and adhesiveness.

[0041] (Other thermoplastic resins) Examples of the above other thermoplastic resins include phenoxy resins, polyamide resins, polyester resins, polycarbonate resins, polyphenylene oxide resins, polyurethane resins, polyacetal resins, polystyrene resins other than the carboxy group-containing styrenic elastomer (A), polyethylene resins, polypropylene resins, polyvinyl resins, and the like. These thermoplastic resins may be used alone or in combination of two or more.

[0042] (Adhesion imparting agent) Examples of the adhesion imparting agent include coumarone-indene resin, terpene resin, terpene-phenol resin, rosin resin, p-t-butylphenol-acetylene resin, phenol-formaldehyde resin, xylene-formaldehyde resin, petroleum-based hydrocarbon resin, hydrogenated hydrocarbon resin, and terpin-based resin. These adhesion imparting agents may be used alone or in combination of two or more kinds.

[0043] (Flame retardant) The above-mentioned flame retardant may be either an organic flame retardant or an inorganic flame retardant. Examples of organic flame retardants include phosphorus-based flame retardants such as melamine phosphate, melamine polyphosphate, guanidine phosphate, guanidine polyphosphate, ammonium phosphate, ammonium polyphosphate, ammonium amide phosphate, ammonium amide polyphosphate, carbamate phosphate, carbamate polyphosphate, aluminum tris(diethylphosphate), aluminum tris(methylethylphosphate), aluminum tris(diphenylphosphate), zinc bis(diethylphosphate), zinc bis(methylethylphosphate), zinc bis(diphenylphosphate), titanyl bis(diethylphosphate), titanium tetrakis(diethylphosphate), titanyl bis(methylethylphosphate), titanium tetrakis(methylethylphosphate), titanyl bis(diphenylphosphate), and titanium tetrakis(diphenylphosphate); nitrogen-based flame retardants such as triazine compounds like melamine, melam, and melamine cyanurate, cyanuric acid compounds, isocyanuric acid compounds, triazole compounds, tetrazole compounds, diazo compounds, and urea; and silicon-based flame retardants such as silicone compounds and silane compounds. Examples of inorganic flame retardants include metal hydroxides such as aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, barium hydroxide, and calcium hydroxide; metal oxides such as tin oxide, aluminum oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, and nickel oxide; and zinc carbonate, magnesium carbonate, barium carbonate, zinc borate, and hydrated glass. These flame retardants may be used alone or in combination of two or more kinds.

[0044] (Hardener) Examples of the above-mentioned hardener include, but are not limited to, amine-based hardeners and acid anhydride-based hardeners. Examples of amine-based hardeners include melamine resins such as methylated melamine resin, butylated melamine resin, and benzoguanamine resin, dicyandiamide, 4,4'-diphenyldiaminosulfone, etc. Examples of acid anhydrides include aromatic acid anhydrides and aliphatic acid anhydrides. These hardeners may be used alone or in combination of two or more kinds.

[0045] (Hardening accelerator) The above hardening accelerator is used for the purpose of accelerating the reaction between the carboxy group-containing styrene-based elastomer (A) and the epoxy resin (C), and a tertiary amine-based hardening accelerator, a tertiary amine salt-based hardening accelerator, an imidazole-based hardening accelerator, etc. can be used.

[0046] Examples of the tertiary amine-based hardening accelerator include benzyldimethylamine, 2-(dimethylaminomethyl)phenol, 2,4,6-tris(dimethylaminomethyl)phenol, tetramethylguanidine, triethanolamine, N,N'-dimethylpiperazine, triethylenediamine, 1,8-diazabicyclo[5.4.0]undecene, etc.

[0047] Examples of the tertiary amine salt-based hardening accelerator include formate, octylate, p-toluenesulfonate, o-phthalate, phenolate, or phenol novolak resin salt of 1,8-diazabicyclo[5.4.0]undecene, and formate, octylate, p-toluenesulfonate, o-phthalate, phenolate, or phenol novolak resin salt of 1,5-diazabicyclo[4.3.0]nonene, etc.

[0048] Examples of imidazole-based curing accelerators include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 1,2-dimethylimidazole, 2-methyl-4-ethylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-methylimidazole, 1-benzyl-2-phenylimidazole, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-undecylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-ethyl-4'-methylimidazolyl-(1')]ethyl-s-triazine, 2,4-diamino-6-[2'-methylimidazolyl-(1')]ethyl-s-triazine isocyanurate adduct, 2-phenylimidazole isocyanurate adduct, 2-phenyl-4,5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole, and the like. These curing accelerators may be used alone or in combination of two or more.

[0049] When the adhesive composition of this embodiment contains a curing accelerator, the content of the curing accelerator is preferably 1 part by mass or more and 15 parts by mass or less, more preferably 1 part by mass or more and 10 parts by mass or less, and even more preferably 2 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the epoxy resin (C). If the content of the curing accelerator is within the above range, excellent adhesiveness and heat resistance can be exhibited.

[0050] (Coupling agent) Examples of the coupling agent include silane coupling agents such as vinyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, p-styryltrimethoxysilane, 3-methacryloxypropylmethyldimethoxysilane, 3-acryloxypropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-ureidopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane, bis(triethoxysilylpropyl)tetrasulfide, 3-isocyanatopropyltriethoxysilane, imidazole silane; titanate coupling agents; aluminate coupling agents; zirconium coupling agents and the like. These may be used alone or in combination of two or more kinds.

[0051] (Heat aging inhibitor) Examples of the heat aging inhibitor include, for example, antioxidants. Specific examples thereof include phenolic antioxidants such as 2,6-di-tert-butyl-4-methylphenol, n-octadecyl 3-(3’,5’-di-tert-butyl-4’-hydroxyphenyl)propionate, tetrakis[methylene-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate]methane, pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl), triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate; sulfur antioxidants such as dilauryl 3,3’-thiodipropionate, dimyristyl 3,3’-dithiopropionate; phosphorus antioxidants such as trisnonylphenyl phosphite, tris(2,4-di-tert-butylphenyl) phosphite and the like. These may be used alone or in combination of two or more kinds.

[0052] (Inorganic filler) Examples of the inorganic filler include powders composed of titanium oxide, aluminum oxide, zinc oxide, carbon black, silica, talc, copper, silver and the like. These may be used alone or in combination of two or more kinds.

[0053] (Lubricant) Examples of the lubricant include oleic acid amide, stearic acid amide, erucic acid amide, etc. These may be used alone or in combination of two or more.

[0054] (Solvent) The adhesive composition of the present embodiment can be produced by mixing each resin component, other additives added as necessary, and other components. The mixing method is not particularly limited as long as the adhesive composition becomes uniform. Since the adhesive composition is preferably used in the form of a solution or dispersion, usually a solvent such as an organic solvent is also used.

[0055] Examples of the solvent include alcohols such as methanol, ethanol, isopropyl alcohol, n-propyl alcohol, isobutyl alcohol, n-butyl alcohol, benzyl alcohol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diacetone alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, and isophorone; aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and mesitylene; esters such as methyl acetate, ethyl acetate, ethylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; aliphatic hydrocarbons such as hexane, heptane, cyclohexane, and methylcyclohexane. These solvents may be used alone or in combination of two or more. When the adhesive composition contains a solvent and is a solution or dispersion (resin varnish) in which each component is dissolved or dispersed in the solvent, coating on the base film and formation of the adhesive layer can be performed smoothly, and an adhesive layer with a desired thickness can be easily obtained.

[0056] 1.6 Dielectric Properties of the Cured Product of the Adhesive Composition 1.6.1 Dielectric Constant of the Cured Product of the Adhesive Composition The relative permittivity (Dk, εr) of the cured product of the adhesive composition measured at a frequency of 10 GHz is preferably less than 3.0. If the relative permittivity is less than 3.0, it can be suitably used for FPC-related products with strict requirements for dielectric properties, which can cope with further increases in signal speed and higher frequencies of signals in recent years. The relative permittivity is preferably 2.8 or less, more preferably 2.7 or less, and even more preferably 2.6 or less. The relative permittivity can be adjusted by the types and contents of the respective components in the adhesive composition. The method for measuring the relative permittivity will be described in detail in the examples below.

[0057] 1.6.2 Dielectric Dissipation Factor of the Cured Product of the Adhesive Composition For the adhesive composition of this embodiment, the dielectric dissipation factor (Df, tanδ) of the cured product of the adhesive composition measured at a frequency of 10 GHz is preferably less than 0.03. If the dielectric dissipation factor is less than 0.03, it can be suitably used for FPC-related products with strict requirements for dielectric properties, which can cope with further increases in signal speed and higher frequencies of signals in recent years. The dielectric dissipation factor is preferably 0.025 or less, more preferably 0.02 or less, even more preferably 0.015 or less, even more preferably 0.01 or less, and particularly preferably 0.005 or less. The method for measuring the dielectric dissipation factor can be measured in the same manner as the method for measuring the relative permittivity described in the examples below.

[0058] 1.7 Applications of the Adhesive Composition The adhesive composition of this embodiment can be suitably used for flexible copper-clad laminates, rigid copper-clad laminates, flexible flat cables, encapsulants, etc.

[0059] The flexible copper-clad laminate can be configured to include a base film on one surface of the adhesive layer in the laminate with an adhesive layer described below, and a copper foil on the other surface of the adhesive layer. Specifically, the flexible copper-clad laminate can be configured such that the base film and the copper foil are bonded together using the laminate with an adhesive layer described below. That is, the flexible copper-clad laminate can be formed by laminating the base film, the adhesive layer, and the copper foil in this order. Note that the adhesive layer and the copper foil may be formed on both surfaces of the base film.

[0060] The rigid copper-clad laminate can be configured to include a plate-shaped base material made of glass epoxy or the like on one surface of the adhesive layer made of the above adhesive composition, and a copper foil on the other surface of the adhesive layer. Specifically, the rigid copper-clad laminate can be configured such that the base material and the copper foil are bonded together using the adhesive layer made of the above adhesive composition. That is, the rigid copper-clad laminate can be formed by laminating the base material, the adhesive layer, and the copper foil in this order. Note that the adhesive layer and the copper foil may be formed on both surfaces of the base material.

[0061] The flexible flat cable can be configured to include a base film on one surface of the adhesive layer in the laminate with an adhesive layer described below, and a copper wiring on the other surface of the adhesive layer. Specifically, the flexible flat cable can be configured such that the base film and the copper wiring are bonded together using the laminate with an adhesive layer described below. That is, the flexible flat cable can be formed by laminating the base film, the adhesive layer, and the copper wiring in this order. Note that the adhesive layer and the copper wiring may be formed on both surfaces of the base film.

[0062] The encapsulant can be configured to include a base film on one surface of the adhesive layer in the laminate with an adhesive layer described below, and a base film on the other surface of the adhesive layer. That is, the encapsulant can be formed by laminating the base film, the adhesive layer, and the base film in this order.

[0063] 2. Laminated Body with Adhesive Layer The laminated body with an adhesive layer according to this embodiment includes an adhesive layer made of the above-described adhesive composition and a base film in contact with at least one surface of the adhesive layer. The adhesive layer is in a B-stage state. The adhesive layer being in a B-stage state means a semi-cured state in which a part of the adhesive composition has started to cure, and a state in which the curing of the adhesive composition further proceeds by heating or the like.

[0064] As one aspect of the laminated body with an adhesive layer, a coverlay film can be mentioned. A coverlay film is usually one in which an adhesive layer is formed on at least one surface of a base film, and is a laminated body in which it is difficult to peel the base film and the adhesive layer.

[0065] Examples of the base film included in the laminated body with an adhesive layer include a polyimide film, a polyetheretherketone film, a polyphenylene sulfide film, an aramid film, a polyethylene naphthalate film, a liquid crystal polymer film, and the like. Among these, from the viewpoints of adhesiveness and electrical properties, a polyimide film, a polyethylene naphthalate film, and a liquid crystal polymer film are preferable.

[0066] As a method for manufacturing a laminated body with an adhesive layer, for example, a resin varnish containing the above-described adhesive composition and a solvent is applied to the surface of a base film such as a polyimide film to form a resin varnish layer, and then a laminated body with an adhesive layer in which a B-stage adhesive layer is formed can be manufactured by removing the solvent from this resin varnish layer.

[0067] The drying temperature when removing the solvent is preferably 40 to 250°C, and more preferably 70 to 170°C. Drying can be performed by passing the laminated body coated with the adhesive composition through a furnace where hot air drying, far-infrared heating, high-frequency induction heating, etc. are performed.

[0068] In addition, if necessary, a release film may be laminated on the surface of the adhesive layer for storage or the like. As the release film, known ones such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release-treated paper, polyolefin resin-coated paper, polymethylpentene (TPX) film, and fluororesin film can be used.

[0069] Another aspect of the laminate with an adhesive layer is a bonding sheet. The bonding sheet is also one in which the above adhesive layer is formed on the surface of the base film, but the base film functions as a release film. Further, the bonding sheet may be in a mode in which an adhesive layer is provided between two release films. The release film is peeled off when the bonding sheet is used. The same release films as those described above can be used.

[0070] As a method for manufacturing the bonding sheet, for example, there is a method of applying a resin varnish containing the above adhesive composition and a solvent on the surface of the release film and drying it in the same manner as in the case of the coverlay film.

[0071] The thickness of the adhesive layer is preferably 5 μm or more and 100 μm or less, more preferably 10 μm or more and 70 μm or less, and still more preferably 10 μm or more and 50 μm or less in order to sufficiently exhibit the adhesive strength. Also, the thickness of the base film is preferably 5 μm or more and 100 μm or less, more preferably 5 μm or more and 50 μm or less, and still more preferably 5 μm or more and 30 μm or less from the viewpoint of thinning the laminate with an adhesive layer.

Examples

[0072] The present invention will be described more specifically based on examples, but the present invention is not limited thereto. In the following, parts and % are based on mass unless otherwise specified.

[0073] 1. Evaluation method (1) Weight average molecular weight Mw Under the following conditions, GPC measurement was carried out to determine the weight-average molecular weight Mw of acid-modified SEBS (a1). The weight-average molecular weight Mw was converted based on the retention time measured by GPC with reference to the retention time of standard polystyrene. Apparatus: Alliance 2695 (manufactured by Waters) Columns: 2 TSKgel SuperMultipore HZ-H 2 TSKgel SuperHZ2500 (manufactured by Tosoh Corporation) Column temperature: 40 °C Eluent: Tetrahydrofuran 0.35 ml / min Detector: RI (differential refractive index detector)

[0074] (2) Acid value 1 g of acid-modified SEBS (a1) was dissolved in 30 ml of toluene, and a device in which "APB-510-20B" manufactured by the same company was connected as a burette to the automatic titrator "AT-510" manufactured by Kyoto Electronics Industry Co., Ltd. was used. Potentiometric titration was carried out using a 0.01 mol / L benzyl alcohol KOH solution as the titration reagent, and the number of mg of KOH per 1 g of the resin was calculated.

[0075] (3) Redelamination property A release PET film with a thickness of 38 μm was prepared, and a liquid adhesive composition was roll-coated on one of its surfaces. Subsequently, the film with the adhesive layer was left standing in an oven and dried at 90°C for 3 minutes to form a B-stage adhesive layer (thickness: 25 μm). Next, the adhesive layer was laminated onto the resin surface of a copper-clad laminate "Pyralux TAS, manufactured by Dupont" (base material 1-A) under the conditions of a temperature of 120°C, a pressure of 0.3 MPa, and a speed of 0.5 m / min, and then the release PET film was peeled off. Next, another copper-clad laminate "Pyralux TAS, manufactured by Dupont" (base material 1-B) was placed on the adhesive layer surface of the laminate composed of base material 1-A / adhesive layer with the copper foil surface facing the adhesive layer side, and left standing for a predetermined time. Thereafter, the peelability of base material 1-B was evaluated. When base material 1-B could be peeled off as it was after being left standing for 10 seconds, it was described as "A", indicating excellent peelability. Also, when base material 1-B could be peeled off as it was after being left standing for 5 seconds, it was described as "B", indicating good peelability. Further, when base material 1-B was partially adhered to the adhesive layer (coating film) and deformed during peeling after being left standing for 5 seconds, it was described as "C", indicating poor peelability.

[0076] (4) Redispersibility 100 g of the liquid adhesive composition was placed in a glass container and left standing at room temperature (23°C) for one day. Subsequently, the adhesive composition was stirred using a mixing rotor and roll-coated onto a PET film so that the dried coating film thickness would be 25 μm. Then, the dried coating film was visually inspected. When the liquid after stirring for 30 minutes was applied and there were no lumps due to undissolved fillers and solid components, it was described as "A", indicating excellent redispersibility at the stage of the coating liquid before forming the adhesive layer. Also, when the liquid after stirring for 60 minutes was applied and there were no lumps due to undissolved fillers and solid components, it was described as "B", indicating good redispersibility at the stage of the coating liquid before forming the adhesive layer. On the other hand, when there was some undissolved filler and solid component in the adhesive composition after stirring for 60 minutes and mesh filtration was required, it was described as "C", indicating poor redispersibility at the stage of the coating liquid before forming the adhesive layer. Also, when a stable coating film could not be formed even with the liquid after mesh filtration, it was described as "D". Note that when this evaluation was "D", no other evaluations were performed.

[0077] (5) Peel Adhesion Strength A release PET film with a thickness of 38 μm was prepared, and a liquid adhesive composition was roll-coated on one of its surfaces. Next, the film with the adhesive layer was left standing in an oven and dried at 90 °C for 3 minutes to form a B-stage adhesive layer (thickness: 25 μm). Next, the adhesive layer was placed on the resin surface of a copper-clad laminate (manufactured by Dupont, "Pyralux TAS") (substrate 1), and lamination was performed under the conditions of a temperature of 120 °C, a pressure of 0.3 MPa, and a speed of 0.5 m / min. Next, the release PET film was peeled off. Next, another copper-clad laminate (manufactured by Dupont, "Pyralux TAH") (substrate 2) was overlaid on the adhesive layer surface of the laminate composed of substrate 1 / adhesive layer, and lamination was performed under the conditions of a temperature of 120 °C, a pressure of 0.3 MPa, and a speed of 0.5 m / min. The laminate in this state was designated as substrate A. Next, this substrate A (substrate 1 / adhesive layer / substrate 2) was heat-pressed at a temperature of 180 °C and a pressure of 3 MPa for 60 minutes. Then, an adhesive test piece cut into a size of 10 mm × 100 mm was obtained from the substrate A after the heat pressing. Next, in order to evaluate the adhesiveness, the 180° peel adhesion strength (normal state) (N / mm) was measured under the conditions of a temperature of 23 °C and a tensile speed of 50 mm / min, and this was taken as the peel adhesion strength (normal state) (N / mm). Note that the width of the adhesive test piece during the above measurement was 10 mm in all cases.

[0078] (6) Dielectric properties (relative permittivity) A release PET film with a thickness of 38 μm was prepared, and the predetermined adhesive composition described in Table 1 was applied to one of its surfaces. Next, the film with the coating was left standing in an oven and dried at 90 °C for 3 minutes to form a film (adhesive layer) with a thickness of 50 μm, and an adhesive layer was obtained. Next, this adhesive layer was left standing in an oven and heat-treated at 180 °C for 60 minutes. Thereafter, the release film was peeled off to obtain a test piece (100 mm × 80 mm) composed of a cured product of the adhesive composition. The relative permittivity (Dk, εr) was measured by the split post dielectric resonator method (SPDR method) using a network analyzer 85071E-300 (manufactured by Agilent Technologies) under the conditions of a temperature of 23 °C and a frequency of 10 GHz.

[0079] 2. Raw materials of the adhesive composition As raw materials for the adhesive composition, the following were prepared. (1) Carboxy group-containing styrene-based elastomer (A) · Acid-modified SEBS (a1) (manufactured by Asahi Kasei Chemicals Corporation, "Tuftec M1913", maleic acid-modified SEBS, acid value: 10 mgKOH / g, weight-average molecular weight Mw = 150,000)

[0080] (2) Rubber (2-1) Styrene-butadiene rubber (B) · Modified SBR (b1) (manufactured by Asahi Kasei Corporation, "Asapren Y031") · Unmodified SBR (b2) (manufactured by Asahi Kasei Corporation, "Asapren 303") (2-2) Rubber for comparison · BR (butadiene rubber) (b3) (manufactured by Nippon Zeon Co., Ltd., "Nipol BR1220") · Acrylic-modified NR (acrylic-modified natural rubber) (b4) (manufactured by MMG Co., Ltd., "DYNAPALY30")

[0081] (3) Epoxy resin (C) · Epoxy resin containing dicyclopentadiene skeleton (DCPD-type epoxy resin) (c1) (manufactured by DIC Corporation, "EPICLON HP-7200") · Epoxy resin containing naphthalene skeleton (NAPH-type epoxy resin) (c2) (manufactured by Nippon Kayaku Co., Ltd., "NC-7000L")

[0082] (3) Others · Curing accelerator (imidazole-based curing accelerator) (manufactured by Shikoku Kasei Co., Ltd., "Curezol C11Z") · Filler (aluminum hydroxide, average particle size 2 μm)

[0083] Note that as the solvent, a mixed solvent composed of toluene and methyl ethyl ketone (mass ratio = 90:10) was used.

[0084] 3. Production and evaluation of the adhesive composition The above raw materials were added to a 1000 ml flask equipped with a stirring device at the predetermined ratios shown in Tables 1 to 2, a solvent was added, and the mixture was stirred at a temperature of 50°C or lower for 3 hours to dissolve, thereby preparing each adhesive composition and conducting evaluations. The results are shown in Tables 1 to 2.

[0085] 4. Manufacture and Evaluation of Laminates with Adhesive Layers Using the above adhesive compositions, laminates with adhesive layers were manufactured and evaluated as described in the explanations regarding the above respective evaluation methods. The results are shown in Tables 1 to 2.

[0086]

Table 1

[0087]

Table 2

[0088] According to Tables 1 to 2, the following can be understood. That is, Sample 1C does not contain styrene-butadiene rubber (B) in the adhesive composition. Also, it does not contain a filler. Therefore, Sample 1C could not suppress the stickiness caused by the soft carboxy group-containing styrene-based elastomer (A) and could not ensure re-peelability.

[0089] Sample 2C is obtained by adding a filler to the adhesive composition of Sample 1C. By containing a filler in the adhesive composition, Sample 2C suppressed the stickiness caused by the soft carboxy group-containing styrene-based elastomer (A) and could ensure re-peelability. However, since Sample 2C does not contain styrene-butadiene rubber (B) in the adhesive composition, a large amount of filler is required to ensure re-peelability. Therefore, Sample 2C had poor redispersibility at the stage of the coating liquid of the adhesive composition before forming the adhesive layer. Also, due to adding a large amount of filler to ensure re-peelability, the amount of the adhesive component in the adhesive composition decreased, and the adhesiveness deteriorated.

[0090] Sample 3C was prepared by using butadiene rubber with poor solubility as a rubber other than styrene-butadiene rubber (B) without adding a filler to the adhesive composition. Therefore, Sample 3C was prone to undissolved residues, and unlike the system using styrene-butadiene rubber, its redispersibility was rated as C. On the other hand, since the tackiness of the paint could be suppressed in Sample 3C, its peelability was rated as A.

[0091] Sample 4C was prepared in the same manner as Sample 3C, without adding a filler to the adhesive composition and using acrylic-modified NR as a rubber other than styrene-butadiene rubber (B). As shown in Table 1, this Sample 4C could not dissolve the adhesive composition in a solvent.

[0092] In contrast, Samples 1 to 12 met the requirements defined in the present disclosure for the adhesive composition. Therefore, Samples 1 to 12 were able to ensure peelability without containing a filler in the adhesive composition. Also, Samples 1 to 12 did not need to use a filler to ensure peelability, and even if a filler was used, the amount of filler used could be small. Thus, it was possible to suppress a decrease in the redispersibility of the filler in the coating liquid of the adhesive composition, and accordingly, an appropriate amount of the adhesive component could be ensured, thereby suppressing a decrease in adhesiveness.

[0093] According to the above results, it can be said that the present disclosure can provide an adhesive composition that can simultaneously satisfy peelability, redispersibility, and adhesiveness without using a filler or by using a small amount of filler supplementarily, and a laminate with an adhesive layer using the same.

[0094] Also, when comparing Sample 3 and Sample 4 with Sample 10 and Sample 11, it was confirmed that higher adhesiveness was obtained when using a NAPH-type epoxy resin, which is one of the epoxy resins having a polycyclic aromatic hydrocarbon skeleton, as the epoxy resin (C) than when using a DCPD-type epoxy resin, which is one of the polyfunctional epoxy resins having an alicyclic skeleton.

[0095] The present invention is not limited to the above-described embodiments and examples, and various modifications can be made without departing from the gist thereof. Further, each configuration shown in the above-described embodiments and examples can be arbitrarily combined with each other.

Claims

1. An adhesive composition containing a carboxy group-containing styrenic elastomer (A), a styrene-butadiene rubber (B), and an epoxy resin (C).

2. The adhesive composition according to claim 1, wherein the content of the styrene-butadiene rubber (B) is 1 part by mass or more and 50 parts by mass or less with respect to 100 parts by mass of the carboxy group-containing styrenic elastomer (A).

3. The adhesive composition according to claim 1, wherein the styrene content ratio of the styrene-butadiene rubber (B) is 10% by mass or more and 70% by mass or less.

4. The adhesive composition according to claim 1, wherein the content of the carboxy group-containing styrenic elastomer (A) is 30 parts by mass or more with respect to 100 parts by mass of the solid content of the adhesive composition.

5. The adhesive composition according to claim 1, wherein the content of the epoxy resin (C) is 1 part by mass or more and 20 parts by mass or less with respect to 100 parts by mass of the carboxy group-containing styrenic elastomer (A).

6. The adhesive composition according to claim 1, wherein the epoxy resin (C) is a polyfunctional epoxy resin having an alicyclic skeleton and / or an epoxy resin having a polycyclic aromatic hydrocarbon skeleton.

7. The adhesive composition according to claim 1, wherein the relative permittivity of the cured product of the adhesive composition measured at a frequency of 10 GHz is less than 3.

0.

8. The adhesive composition according to any one of claims 1 to 7, which is used for a flexible copper-clad laminate, a rigid copper-clad laminate, a flexible flat cable, or a sealing material.

9. An adhesive layer laminate comprising an adhesive layer composed of the adhesive composition according to any one of claims 1 to 7 and a base film in contact with at least one surface of the adhesive layer, wherein the adhesive layer is in a B-stage state. ​ ​ ​ ​ ​ ​ ​ ​ ​

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