Adhesive composition and coverlay film

Abstract

To provide an adhesive composition which is excellent in adhesion to a base material resin used in FPC and a metallic foil such as a copper foil, and has a low dielectric constant.SOLUTION: An adhesive composition contains a polyamide elastomer, an epoxy resin, and an epoxy resin curing agent, wherein a content of the polyamide elastomer is 17 to 99 mass% with respect to a mass (solid content excluding solvent) of the adhesive composition, and a content of the epoxy resin is 3 to 46 mass% with respect to the mass% (solid content excluding solvent) of the adhesive composition.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an adhesive composition and a coverlay film. More specifically, it relates to an adhesive composition and a coverlay film used for flexible printed circuit boards.

Background Art

[0002] In order to cope with the multifunctionalization and miniaturization of electronic devices such as personal computers (PCs) and smartphones, and to incorporate electronic circuit boards into narrow and complex interiors, flexible printed circuit boards (Flexible Printed Circuits, hereinafter sometimes referred to as FPCs), which are thin, lightweight, and foldable, are widely used. In recent years, the miniaturization, lightweight, high density, and high output of electronic devices have advanced, and the requirements for the performance of wiring boards (electronic circuit boards) have become increasingly sophisticated. In particular, in order to increase the transmission speed of FPCs, high-frequency signals are being used. Along with this, the requirements for low dielectric characteristics (low dielectric constant, low dielectric tangent) in the high-frequency region of FPCs have been increasing. In order to achieve such low dielectric characteristics, measures have been taken to reduce the dielectric loss of the base resin and adhesive composition of FPCs.

[0003] Fluorine-based resins are known to have low dielectric properties, and as base resins used in FPCs, polytetrafluoroethylene (hereinafter sometimes referred to as PTFE), tetrafluoroethylene-hexafluoropropylene copolymer (hereinafter sometimes referred to as FEP), and tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (hereinafter sometimes referred to as PFA) have been proposed as alternatives to conventional polyimide (PI) and polyethylene terephthalate (PET) (see Patent Document 1). Furthermore, polyolefin resins are known to have low dielectric properties, and as adhesives for FPCs used in FPCs, modified polyamide adhesive compositions incorporating an olefin skeleton have been proposed to improve the electrical properties of FPCs (see Patent Document 2). In addition, adhesive compositions using aromatic olefin oligomer type modifiers and epoxy resins, and coverlays for flexible printed circuit boards have been proposed (see Patent Document 3). [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2017-24265 [Patent Document 2] Japanese Patent Publication No. 2007-284515 [Patent Document 3] Japanese Patent Publication No. 2007-63306 [Overview of the project] [Problems that the invention aims to solve]

[0005] However, because substrate resins with low dielectric properties have low polarity, using conventional epoxy or acrylic adhesive compositions results in weak adhesion, making it difficult to manufacture FPC components such as coverlay films and laminates. Furthermore, epoxy and acrylic adhesive compositions do not exhibit excellent low dielectric properties, which impairs the dielectric properties of FPCs.

[0006] Furthermore, when using a fluororesin with low dielectric properties as the base resin, there is a problem of weak adhesion to copper foil and the like.

[0007] The purpose of this technology is to provide an adhesive composition that exhibits excellent adhesion to base resins and metal foils such as copper foil used in FPCs, while also having a low dielectric constant. [Means for solving the problem]

[0008] The inventors have found that an adhesive composition having a specific configuration exhibits excellent adhesion to a base resin and also has a low dielectric constant.

[0009] In other words, this technology contains a polyamide elastomer, an epoxy resin, and an epoxy resin curing agent, wherein the polyamide elastomer content is 17 to 99% by mass relative to the mass of the adhesive composition (solid content excluding solvent). The present invention provides an adhesive composition in which the epoxy resin content is 3 to 46% by mass relative to the mass of the adhesive composition (solid content excluding solvent). The epoxy resin curing agent content may be 3 to 37% by mass relative to the mass (solid content excluding solvent) of the adhesive composition. In adhesive compositions according to this technology, the polyamide elastomer may be a solvent-soluble polyamide elastomer. In adhesive compositions according to this technology, the epoxy resin may be selected from the group consisting of dicyclopentadiene-type epoxy resins, triphenylmethane-type epoxy resins, and novolac-type epoxy resins. In adhesive compositions according to this technology, the novolac-type epoxy resin may be a biphenylene novolac-type epoxy resin and / or a naphthol-cresol novolac-type epoxy resin. In the adhesive composition according to this technology, the epoxy resin curing agent may be a phenolic curing agent. Adhesive compositions conforming to this technology may further contain a curing accelerator. In an adhesive composition according to this technology, the peel strength of the adhesive interface when the adhesive composition is bonded to a base resin may be 10 N / 10 mm or more. Adhesive compositions conforming to this technology may have a dielectric constant of 3.1 or less. In adhesive compositions according to this technology, the base resin may be polyimide or polytetrafluoroethylene. This technology provides a coverlay film in which the adhesive composition is applied to at least one surface. [Effects of the Invention]

[0010] This technology makes it possible to provide an adhesive composition that has excellent adhesion to a base resin and a low dielectric constant. Furthermore, the effects of this technology are not necessarily limited to those described herein, but may include any of the effects described in this specification. [Modes for carrying out the invention]

[0011] The following describes preferred embodiments for implementing this technology. Note that the embodiments described below represent typical embodiments of this technology, and the scope of this technology is not limited to these embodiments.

[0012] This technology will be explained in the following order. 1. Description of this technology 2. First Embodiment (Example of Adhesive Composition) (1) Composition of the adhesive composition (2) Explanation of each component (3) Physical properties (4) Method for manufacturing adhesive composition (5) Use of adhesive composition 3. Examples

[0013] 1. Description of this technology

[0014] In a communication device of a fifth-generation mobile communication system (5G) that requires high-speed communication, the material constituting the flexible printed circuit board is important to have a low dielectric constant. As such a low-dielectric constant material, using a fluororesin disclosed in Patent Document 1 as a base resin and the adhesive compositions disclosed in Patent Documents 2 and 3 have been proposed. However, these adhesive compositions have been inferior in adhesion to the base resin using a fluororesin.

[0015] The inventor has found that by containing a polyamide elastomer, an epoxy resin, and an epoxy resin curing agent in an adhesive composition, and the content of the polyamide elastomer being 17 to 99% by mass with respect to the mass of the adhesive composition (solid content excluding solvent), and the content of the epoxy resin being 3 to 46% by mass with respect to the mass of the adhesive composition (solid content excluding solvent), the adhesion to the base resin is improved. The epoxy resin may be at least one selected from the group consisting of dicyclopentadiene-type epoxy resin, triphenylmethane-type epoxy resin, and novolak-type epoxy resin. The novolak-type epoxy resin may be a biphenylene novolak-type epoxy resin and / or a naphthol-cresol novolak-type epoxy resin. The epoxy resin curing agent may be a phenolic curing agent. This technology may further contain an amine catalyst.

[0016] The dielectric constant of the adhesive composition according to this technology may preferably be 3.1 or less, more preferably 2.9 or less, and even more preferably 2.9 or less. The adhesive composition according to this technology may preferably have a peel strength at the adhesion interface when the adhesive composition and the base resin are adhered of 10 N / 10 mm or more, more preferably 13 N / 10 mm or more, and even more preferably 15 N / 10 mm or more.

[0017] 2. First Embodiment (Example of Adhesive Composition)

[0018] (1) Configuration of Adhesive Composition

[0019] The adhesive composition of this embodiment contains a polyamide elastomer, an epoxy resin, and an epoxy resin curing agent. The adhesive composition of this embodiment may also further contain a curing accelerator.

[0020] (2) Explanation of each component

[0021] [Polyamide elastomer]

[0022] The polyamide elastomer in the adhesive composition of this embodiment may be a polyether ester amide obtained by the reaction of a polyamide component with a polyether ester component consisting of polyoxyalkylene glycol and dicarboxylic acid, or it may be a polyether amide obtained by the reaction of a polyamide component with both ends of a polyoxyalkylene glycol aminated or carboxylated, with a polyether component consisting of dicarboxylic acid or diamine.

[0023] Specifically, polyamide components include polyamides produced from aliphatic, alicyclic, or aromatic diamines such as hexamethylenediamine, 2,2,4-trimethylhexamethylenediamine, 2,4,4-trimethylhexamethylenediamine, bis(4-aminocyclohexyl)methane, bis(4-amino-3-methylcyclohexyl)methane, and xylylenediamines, and aliphatic, alicyclic, or aromatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, dodecanediic acid, cyclohexanedicarboxylic acid, terephthalic acid, isophthalic acid, and polymerized fatty acids; polyamides produced from aminocarboxylic acids such as ω-aminocaproic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid; polyamides produced from lactams such as ε-caprolactam and laurolactam; copolymerized polyamides consisting of these components; or mixtures of these polyamides. In particular, polyamides produced from hexamethylenediamine and adipic acid, hexamethylenediamine and azelaic acid and / or sebacic acid and polymerized fatty acids, 12-aminododecanoic acid, and caprolactam are preferably used. The number average molecular weight of these polyamide components is preferably in the range of 500 to 5,000.

[0024] Examples of polyoxyalkylene glycols used in the adhesive composition of this embodiment include polyoxyethylene glycol, polyoxypropylene glycol, polyoxytetramethylene glycol, block copolymers or random copolymers of ethylene oxide and propylene oxide, block copolymers or random copolymers of ethylene oxide and tetrahydrofuran, and those in which both ends are aminated or carboxylated. The number average molecular weight of these polyoxyalkylene glycols is preferably in the range of 200 to 3,000.

[0025] The dicarboxylic acid used in the adhesive composition of this embodiment is preferably a dicarboxylic acid having 6 to 20 carbon atoms. Specifically, examples include aliphatic dicarboxylic acids such as adipic acid, azelaic acid, sebacic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid and isophthalic acid; and alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid.

[0026] In particular, from the viewpoint of polymerizability and the physical properties of the polyamide elastomer, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, and isophthalic acid are preferably used.

[0027] Examples of diamines include the aromatic, alicyclic, and aliphatic diamines mentioned above. Among these, hexamethylenediamine is preferably used.

[0028] From the viewpoint of suppressing a decrease in the impact resistance of the adhesive composition, and from the viewpoint of suppressing a decrease in the mechanical strength and thermal properties of the adhesive composition, the ratio of the polyamide component to the polyether ester component or polyether component of the polyamide elastomer is preferably in the range of 95 / 5 to 20 / 80 by weight.

[0029] Any method that yields a uniform elastomer can be used as a method for producing polyamide elastomers. For example, polyether ester amides can be obtained by first synthesizing a polyamide oligomer, adding polyoxyalkylene glycol and dicarboxylic acid, heating, and then polymerizing under reduced pressure. Alternatively, they can be obtained by charging a polyamide-forming monomer, polyoxyalkylene glycol, and dicarboxylic acid together, heating to homogenize, and then polymerizing under reduced pressure.

[0030] The polyamide elastomer in the adhesive composition of this embodiment is preferably solvent-soluble. Examples of solvents include single organic solvents and mixed organic solvents. Examples of single organic solvents include alcohol-based solvents such as methanol, ethanol, n-propanol, isopropanol, n-butyl alcohol, isobutyl alcohol, benzyl alcohol, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, diethylene glycol monomethyl ether, and diacetone alcohol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, cyclohexanone, and isophorone; aromatic solvents such as toluene, xylene, ethylbenzene, and mesitylene; ester-based solvents such as methyl acetate, ethyl acetate, ethylene glycol monomethyl ether acetate, and 3-methoxybutyl acetate; chlorine-based solvents such as chloroform, carbon tetrachloride, dichloromethane, and trichloroethylene; and dimethylformamide, dimethylacetamide, and n-methyl-2-pyrrolidone. Examples of mixed organic solvents include toluene / methanol, toluene / isopropanol, n-propanol / cyclohexane, n-propanol / methylcyclohexane, cyclohexanone / n-propanol, and cyclohexanone / methyl ethyl ketone. The polyamide elastomer in the adhesive composition of this embodiment is preferably one that, for example, is dissolved at a resin concentration of 10% by weight at a temperature of 50°C, then left to stand overnight at 23°C, and when observed visually, is dissolved, turbid, and gel-like. Examples of commercially available polyamide elastomers of this type include "TPAE-32" (manufactured by T&K TOKA), "TPAE-12" (manufactured by T&K TOKA), "TPAE-617" (manufactured by T&K TOKA), "TPAE-H471EP" (manufactured by T&K TOKA), and "TPAE-826" (manufactured by T&K TOKA).

[0031] From the viewpoint of solubility in solvents, the polyamide elastomer content is 17% by mass or more, preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and even more preferably 70% by mass or more, based on the mass of the adhesive composition (solids excluding solvent). Furthermore, the polyamide elastomer content is 99% by mass or less, preferably 95% by mass or less, more preferably 90% by mass or less, even more preferably 85% by mass or less, and even more preferably 80% by mass or less, based on the mass of the adhesive composition (solids excluding solvent).

[0032] [Epoxy resin]

[0033] The epoxy resin in the adhesive composition of this embodiment has epoxy groups in its molecule, and may have two or more epoxy groups in its molecule. The epoxy resin is preferably a heat-resistant epoxy resin. For example, an epoxy resin with a softening point of 50°C or higher can be preferably used as the heat-resistant epoxy resin. Furthermore, an epoxy resin with a high glass transition temperature (Tg) can be preferably used as such a heat-resistant epoxy resin. Specifically, for example, an epoxy resin with a glass transition temperature (Tg) of 150°C or higher (DMA measurement) can be preferably used.

[0034] Such epoxy resins are not particularly limited, but at least one selected from the group consisting of dicyclopentadiene type epoxy resins, novolac type epoxy resins, triphenylmethane type epoxy resins, biphenyl type epoxy resins, naphthalene type epoxy resins, bisphenol A type epoxy resins, bisphenol F type epoxy resins, and alicyclic epoxy resins can be used. As novolac type epoxy resins, for example, biphenylene novolac type epoxy resins and / or naphthol-cresol novolac type epoxy resins can be used. Preferably, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, or novolac type epoxy resins can be used, and more preferably, dicyclopentadiene type epoxy resins, triphenylmethane type epoxy resins, biphenylene novolac type epoxy resins, or naphthol-cresol novolac type epoxy resins can be used. Examples of commercially available dicyclopentadiene-type epoxy resins include the trade name "XD-1000" (manufactured by Nippon Kayaku Co., Ltd.), examples of triphenylmethane-type epoxy resins include the trade name "EPPN-502H" (manufactured by Nippon Kayaku Co., Ltd.), examples of biphenylene novolac-type epoxy resins include the trade name "NC-3000-H" (manufactured by Nippon Kayaku Co., Ltd.), and examples of naphthol-cresol novolac-type epoxy resins include the trade name "NC-7000L" (manufactured by Nippon Kayaku Co., Ltd.).

[0035] From the viewpoint of obtaining an adhesive composition that has excellent adhesion to the base resin, excellent heat resistance, and a low dielectric constant, in the adhesive composition of this embodiment, the epoxy resin content is 3% by mass or more, preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 12% by mass or more, and even more preferably 15% by mass or more, based on the mass of the adhesive composition (solids excluding solvent). Furthermore, the epoxy resin content is 46% by mass or less, preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less, and even more preferably 20% by mass or less, based on the mass of the adhesive composition (solids excluding solvent).

[0036] [Epoxy resin hardener]

[0037] The adhesive composition of this embodiment contains an epoxy resin curing agent. As the epoxy resin curing agent, it is preferable to use, for example, a phenolic curing agent. The phenolic curing agent is a general category of monomers, oligomers, and polymers having two or more phenolic hydroxyl groups in a single molecule, and its molecular weight and molecular structure are not particularly limited. Such phenolic curing agents can be synthesized by reacting phenol with bisalkoxymethylbenzene, etc. A commercially available phenolic curing agent is the trade name "KAYAHARD GPH-65" (manufactured by Nippon Kayaku Co., Ltd.).

[0038] From the viewpoint of ensuring sufficient cross-linking reaction (curing reaction) of the epoxy resin and improving the heat resistance of the adhesive composition, in the adhesive composition of this embodiment, the content of the epoxy resin curing agent is preferably 3% by mass or more, more preferably 5% by mass or more, even more preferably 10% by mass or more, and even more preferably 15% by mass or more, based on the mass of the adhesive composition (solid content excluding solvent). Furthermore, the content of the epoxy resin curing agent is preferably 37% by mass or less, more preferably 30% by mass or less, even more preferably 25% by mass or less, and even more preferably 20% by mass or less, based on the mass of the adhesive composition (solid content excluding solvent).

[0039] [Curing accelerator]

[0040] The adhesive composition of this embodiment may further contain a curing accelerator. The curing accelerator can be any compound that has catalytic activity to promote the crosslinking reaction between the epoxy resin and the epoxy resin curing agent.

[0041] For example, examples of curing accelerators for epoxy resins include tertiary amines, cyclic amines, imidazoles, organophosphorus compounds, and quaternary ammonium salts. Here, if necessary, metal carboxylate salts may be added to further accelerate the curing reaction. A commercially available curing accelerator is the trade name "Curezol (registered trademark) 2E4MZ-CN" (manufactured by Shikoku Chemicals, Inc.) (imidazole-based epoxy resin curing accelerator).

[0042] From the viewpoint of promoting the curing reaction, in the adhesive composition of this embodiment, the content of the curing accelerator is preferably 0.17% by mass or more, more preferably 0.18% by mass or more, even more preferably 0.19% by mass or more, and even more preferably 0.20% by mass or more, based on the mass of the adhesive composition (solid content excluding solvent). Furthermore, the content of the curing accelerator is preferably 1.0% by mass or less, more preferably 0.8% by mass or less, even more preferably 0.6% by mass or less, and even more preferably 0.4% by mass or less, based on the mass of the adhesive composition (solid content excluding solvent).

[0043] [Other ingredients]

[0044] The adhesive composition of this embodiment may contain components other than those listed above for the purpose of further improving its functionality. Examples include UV inhibitors, antioxidants, coupling agents, plasticizers, fluxes, flame retardants, colorants, dispersants, emulsifiers, deelasticizers, diluents, defoamers, ion trappers, inorganic fillers, and organic fillers.

[0045] (3) Physical properties

[0046] [Peel strength]

[0047] In the adhesive composition according to this embodiment, peel strength is used as a parameter representing the adhesive strength to a base resin or a metal such as copper foil. A larger peel strength at the adhesive interface when the adhesive composition and the base resin are bonded indicates greater adhesive strength and superior adhesion. In the adhesive composition according to this embodiment, the peel strength at the adhesive interface when the adhesive composition and the base resin are bonded is preferably 10 N / 10 mm or more, more preferably 11 N / 10 mm or more, and even more preferably 12 N / 10 mm or more. More specifically, when the base resin is a polyimide resin, the peel strength at the adhesive interface when the adhesive composition and the polyimide resin are bonded is preferably 10 N / 10 mm or more, more preferably 11 N / 10 mm or more, and even more preferably 12 N / 10 mm or more. When the base resin is a polytetrafluoroethylene resin, the peel strength at the adhesive interface when the adhesive composition and the polytetrafluoroethylene resin are bonded is preferably 10 N / 10 mm or more, more preferably 13 N / 10 mm or more, and even more preferably 15 N / 10 mm or more. The method for measuring peel strength will be described below. Since the adhesive composition can be used as a solution-type adhesive or a sheet-type adhesive, the method for preparing test specimens for each will be described below.

[0048] (Preparation of test specimens for solution-type adhesives)

[0049] A solid adhesive composition is dissolved in a solvent at 60°C to prepare a solution-type adhesive. A 25 μm thick polyimide film (product name "Kapton® V" (manufactured by Toray DuPont)) or a 50 μm thick polytetrafluoroethylene sheet (product name "Valflon® Double-Sided Treatment Tape 7990" (manufactured by Valqua Corporation)) is used as the substrate. The solution-type adhesive is applied using a bar coater (wire bar No. #38, wire diameter 0.95 mm, mesh 27 strands / IN width, application rate 38-47.5 WET g / m²). 2Using a solution-type adhesive (manufactured by Marukyo Giken Co., Ltd.), the adhesive is applied to the substrate to a thickness of 10 μm. The substrate coated with the solution-type adhesive is dried at 100°C for 2 minutes to prepare a substrate piece in which the solution-type adhesive has hardened. A 12 μm thick copper foil (product name "Surface-treated copper foil" (manufactured by Fukuda Metal Foil & Powder Co., Ltd.)) is pressed onto the hardened 10 μm thick solution-type adhesive at a temperature of 150°C and a pressure of 3 MPa for 3 minutes. After that, it is heated and cured at a temperature of 150°C and a pressure of 3 MPa for 30 minutes to obtain the test piece.

[0050] (Preparation of test specimens for sheet-type adhesives)

[0051] A solid adhesive composition is dissolved in a solvent at 60°C to prepare a solution-type adhesive. A PET film (product name "KOBATECH RF(registered trademark) 130SGN" (manufactured by Kobayashi Co., Ltd.)) is used as the release film, and the solution-type adhesive is applied using a bar coater (wire bar No. #68, wire diameter 1.7 mm, mesh 14 strands / IN width, application rate 68-85 WET g / m²). 2 A sheet-type adhesive is prepared by applying a 25 μm thick polyimide film (product name "Kapton® V" (Toray DuPont)) to a release film. A 25 μm thick polyimide film (product name "Valflon® Double-Sided Treatment Tape 7990" (Valqua Corporation)) or a 50 μm thick polytetrafluoroethylene sheet (product name "Valflon® Double-Sided Treatment Tape 7990" (Valqua Corporation)) is used as the substrate. The sheet-type adhesive is temporarily bonded to the polyimide film or polytetrafluoroethylene sheet at 100°C, and the release film is peeled off. A 12 μm thick copper foil (product name "Surface-Treated Copper Foil" (Fukuda Metal Foil Powder Co., Ltd.)) is pressed onto the surface from which the release film was peeled at a temperature of 150°C and a pressure of 0.3 MPa for 3 minutes. After that, it is heated and cured at a temperature of 150°C and a pressure of 3 MPa for 30 minutes to prepare the test piece.

[0052] (Peel test)

[0053] The test specimen is cut to a width of 10 mm to be used as the measurement sample. The measurement sample is pre-treated in accordance with JIS Z0237 "Test Method for Adhesive Tapes and Adhesive Sheets". Using the adhesive / film peel analysis device "VPA-2" (manufactured by Kyowa Interface Science Co., Ltd.), a tensile test is performed in the 90° direction at a peeling speed of 300 mm / min in accordance with JIS Z0237, and the peel strength (N / 10 mm) is measured to determine the peel strength.

[0054] [dielectric constant]

[0055] In the adhesive composition according to this embodiment, the dielectric constant is preferably 3.1 or less, more preferably 2.9 or less, even more preferably 2.7 or less, and even more preferably 2.5 or less. The method for measuring the dielectric constant will be described below.

[0056] (Measurement of dielectric constant)

[0057] The sheet-type adhesive, with the release film removed, is processed into a donut shape with an outer diameter of φ7.00 mm and an inner diameter of φ3.04 mm to prepare the sample. The sample is pressed into a coaxial sample holder (product name "CSH-APC7" (manufactured by EM Lab), sample holder length 2 mm). The port of the vector network analyzer (product name "8720ES" (manufactured by Agilent Technologies)) is connected to the coaxial sample holder with an APC-7 cable. The vector network analyzer is warmed up for 60 minutes. With the sample mounted in the coaxial sample holder, the S-parameter at a frequency of 10 G is measured and converted to the dielectric constant.

[0058] (4) Method for manufacturing adhesive composition

[0059] The adhesive composition according to this embodiment is obtained by stirring and mixing the above-mentioned polyamide elastomer, epoxy resin, epoxy resin curing agent, and other components. The obtained adhesive composition is usually used by dissolving it in a solvent. As the solvent, a solvent that dissolves the polyamide elastomer can be used. Here, if the polyamide elastomer is an alcohol-soluble polyamide elastomer, it is preferable to use a mixed solvent that is a combination of an alcohol-based solvent and one or more other solvents. For example, a mixture of an alcohol-based solvent and a ketone-based solvent, or a mixture of an alcohol-based solvent, an aromatic solvent, and a ketone-based solvent can be used. In the case of the alcohol-soluble polyamide elastomer, it is preferable to set the amount of alcohol relative to the total amount of solvent used in the adhesive composition to a range of 20 to 80% by mass. Within this range, all resins of the polyamide elastomer and epoxy resin dissolve well. When dissolving the adhesive composition in the solvent, it is heated as appropriate. For example, it is preferable to heat it to 50°C or higher.

[0060] As described above, when using an adhesive composition by dissolving it, the resin solids content is preferably set to 3 to 80% by mass, and more preferably to 10 to 50% by mass, from the viewpoint of forming a desired film thickness and suppressing an increase in the viscosity of the solution to achieve uniform coating.

[0061] (5) Use of adhesive composition

[0062] (Flexible copper-clad laminate)

[0063] A flexible copper-clad laminate is produced by coating one surface of an electrically insulating substrate film, such as a polyimide film, drying it at a temperature of 40 to 250°C, preferably 70 to 170°C, for about 2 to 10 minutes, and then heat-laminating it with copper foil at 80 to 150°C. The adhesive composition is further cured by after-curing (100 to 200°C, 30 minutes to 4 hours) of this flexible copper-clad laminate to obtain the final flexible copper-clad laminate. The thickness of the adhesive composition after drying is usually 5 to 45 μm, preferably 5 to 18 μm.

[0064] (Coverlay film)

[0065] A coverlay film is prepared by coating one surface of an electrically insulating substrate film, such as a polyimide film, with the adhesive composition solution and drying it at a temperature of 40 to 250°C, preferably 70 to 170°C, for about 2 to 10 minutes. The drying is carried out by passing the film through a furnace that uses hot air drying, far-infrared heating, high-frequency induction heating, etc. The thickness of the adhesive composition after drying is usually 5 to 45 μm, preferably 10 to 35 μm. A release film may be temporarily laminated onto the adhesive-coated surface of the coverlay film obtained in this way for storage purposes. As the release film, known films such as polyethylene terephthalate film, polyethylene film, polypropylene film, silicone release-treated paper, polyolefin resin coated paper, TPX film, and fluororesin film can be used.

[0066] This technology can also employ the following configuration: [1] Polyamide elastomer and Epoxy resin and Epoxy resin hardener and It contains, The polyamide elastomer content is 17 to 99% by mass relative to the mass of the adhesive composition (solid content excluding solvent). An adhesive composition in which the epoxy resin content is 3 to 46% by mass relative to the mass of the adhesive composition (solid content excluding solvent). [2] The adhesive composition according to [1], wherein the content of the epoxy resin curing agent is 3 to 37% by mass with respect to the mass (solid content excluding solvent) of the adhesive composition. [3] The adhesive composition according to [1] or [2], wherein the polyamide elastomer is a solvent-soluble polyamide elastomer. [4] The epoxy resin is selected from at least one of the group consisting of dicyclopentadiene type epoxy resin, triphenylmethane type epoxy resin, and novolac type epoxy resin, according to any one of [1] to [3]. [5] The adhesive composition according to [4], wherein the novolac-type epoxy resin is a biphenylene novolac-type epoxy resin and / or a naphthol-cresol novolac-type epoxy resin. [6] The epoxy resin curing agent is a phenolic curing agent, and the adhesive composition is as described in any one of [1] to [5]. [7] Furthermore, the adhesive composition according to any one of [1] to [6] contains a curing accelerator. [8] The adhesive composition according to any one of [1] to [7], wherein the peel strength of the adhesive interface when the adhesive composition is bonded to a base resin is 10 N / 10 mm or more. [9] The adhesive composition according to any one of the claims [1] to [8], wherein the dielectric constant is 3.1 or less.

[10] The adhesive composition according to [8], wherein the base resin is polyimide or polytetrafluoroethylene.

[11] A coverlay film having the adhesive composition described in [1] applied to at least one of its surfaces. [Examples]

[0067] 3. Examples The present invention will be described in more detail below based on the examples. The examples described below are representative examples of the present invention, and the scope of the present invention is not limited to these examples.

[0068] In this embodiment, the peel strength and dielectric constant were determined by the measurement method described in the above-mentioned embodiment.

[0069] [Example 1]

[0070] (Preparation of test specimens for solution-type adhesives)

[0071] An adhesive composition containing 19 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 1 part by mass of "XD-1000" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, 0.79 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, and 0.05 parts by mass of "Curezol® 2E4MZ" (manufactured by Shikoku Chemicals Co., Ltd.) as a curing accelerator was dissolved in 100 parts by mass of a solvent (composition ratio: toluene:methanol:cyclohexanone = 40:20:40 mixed solvent) at 60°C to prepare a solution-type adhesive. In the adhesive composition, the polyamide elastomer content was 91.2% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 4.80% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 3.79% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.24% by mass relative to the mass of the adhesive composition (solids excluding solvent).

[0072] As the substrate, a 25 μm thick polyimide film (product name "Kapton® V" (manufactured by Toray DuPont)) or a 50 μm thick polytetrafluoroethylene sheet (product name "Valflon® Double-Sided Treatment Tape 7990" (manufactured by Valqua Corporation)) was used. A solution-type adhesive was applied using a bar coater (wire bar No. #38, wire diameter 0.95 mm, mesh 27 strands / IN width, application rate 38-47.5 WET g / m). 2 Using a solution-type adhesive (manufactured by Marukyo Giken Co., Ltd.), the adhesive was applied to the substrate to a thickness of 10 μm. The substrate coated with the solution-type adhesive was dried at 100°C for 2 minutes to prepare a substrate piece in which the solution-type adhesive had hardened. A 12 μm thick copper foil (product name "Surface-treated copper foil" (manufactured by Fukuda Metal Foil & Powder Co., Ltd.)) was pressed onto the hardened 10 μm thick solution-type adhesive at a temperature of 150°C and a pressure of 3 MPa for 3 minutes. After that, it was heated and cured at a temperature of 150°C and a pressure of 3 MPa for 30 minutes to obtain the test piece.

[0073] (Preparation of test specimens for sheet-type adhesives)

[0074] The adhesive composition used in preparing the solution-type adhesive was dissolved in a solvent at 60°C to prepare the solution-type adhesive. A PET film (product name "KOBATECH RF(registered trademark) 130SGN" (manufactured by Kobayashi Co., Ltd.)) was used as the release film, and the solution-type adhesive was applied using a bar coater (wire bar No. #68, wire diameter 1.7 mm, mesh 14 strands / IN width, application rate 68-85 WET g / m²). 2A sheet-type adhesive was prepared by applying a 25 μm thick polyimide film (manufactured by Marukyo Giken Co., Ltd.) onto a release film. A 25 μm thick polyimide film (product name "Kapton® V" (manufactured by Toray DuPont)) or a 50 μm thick polytetrafluoroethylene sheet (product name "Valflon® Double-Sided Treatment Tape 7990" (manufactured by Valqua Corporation)) was used as the substrate. The sheet-type adhesive was temporarily bonded to the polyimide film or polytetrafluoroethylene sheet at 100°C, and the release film was peeled off. A 12 μm thick copper foil (product name "Surface-Treated Copper Foil" (manufactured by Fukuda Metal Foil & Powder Co., Ltd.)) was pressed onto the surface from which the release film had been peeled off at a temperature of 150°C and a pressure of 0.3 MPa for 3 minutes. After that, it was heated and cured at a temperature of 150°C and a pressure of 3 MPa for 30 minutes to obtain the test specimen.

[0075] The peel strength and dielectric constant of the obtained test specimens were measured using the methods for measuring peel strength and dielectric constant described in 2.(3) above. The results are shown in Table 1. In addition, the state of fracture was confirmed visually during the peel test. In both the solution-type adhesive and the sheet-type adhesive, the copper foil was fractured when peeling it from the base material, which was a polyimide film and a polytetrafluoroethylene sheet.

[0076] [Example 2]

[0077] This method differs from Example 1 in that it contains 17 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 3 parts by mass of "XD-1000" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, and 2.37 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, as an epoxy resin curing agent. However, all other conditions and methods were the same as in Example 1 to obtain a solution-type adhesive and a sheet-type adhesive. In the adhesive composition, the polyamide elastomer content was 75.8% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 13.4% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 10.6% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.22% by mass relative to the mass of the adhesive composition (solids excluding solvent). The obtained physical properties are as shown in Table 1. During the peel test, the state of failure was confirmed visually. In both the solution-type adhesive and the sheet-type adhesive, the copper foil was damaged when peeled from the base material, which was a polyimide film or polytetrafluoroethylene sheet.

[0078] [Example 3]

[0079] This method differs from Example 1 in that it contains 15 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 5 parts by mass of "XD-1000" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, and 3.95 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, as an epoxy resin curing agent. However, all other conditions and methods were the same as in Example 1 to obtain a solution-type adhesive and a sheet-type adhesive. In the adhesive composition, the polyamide elastomer content was 62.5% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 20.8% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 16.5% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.21% by mass relative to the mass of the adhesive composition (solids excluding solvent). The obtained physical properties are as shown in Table 1. During the peel test, the state of failure was confirmed visually. In both the solution-type adhesive and the sheet-type adhesive, the copper foil was damaged when peeled from the base material, which was a polyimide film or polytetrafluoroethylene sheet.

[0080] [Example 4]

[0081] This method differs from Example 1 in that it contains 13 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 7 parts by mass of "XD-1000" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, and 5.5 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, as an epoxy resin curing agent. However, all other conditions and methods were the same as in Example 1 to obtain a solution-type adhesive and a sheet-type adhesive. In the adhesive composition, the polyamide elastomer content was 50.9% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 27.4% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 21.5% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.20% by mass relative to the mass of the adhesive composition (solids excluding solvent). The obtained physical properties are as shown in Table 1. During the peel test, the state of failure was confirmed visually. In both the solution-type adhesive and the sheet-type adhesive, the copper foil was damaged when peeled from the base material, which was a polyimide film or polytetrafluoroethylene sheet.

[0082] [Example 5]

[0083] This invention differs from Example 1 in that it contains 10 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 10 parts by mass of "XD-1000" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, and 7.9 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, as an epoxy resin curing agent. However, all other conditions and methods were the same as in Example 1 to obtain a solution-type adhesive and a sheet-type adhesive. In the adhesive composition, the polyamide elastomer content was 35.8% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 35.8% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 28.3% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.18% by mass relative to the mass of the adhesive composition (solids excluding solvent). The obtained physical properties are as shown in Table 1. During the peel test, the state of failure was confirmed visually. In both the solution-type adhesive and the sheet-type adhesive, the copper foil was damaged when peeled from the base material, which was a polyimide film or polytetrafluoroethylene sheet.

[0084] [Comparative Example 1]

[0085] This method differs from Example 1 in that it contains 5 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 15 parts by mass of "XD-1000" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, and 11.85 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, as an epoxy resin curing agent. However, all other conditions and methods were the same as in Example 1 to obtain a solution-type adhesive and a sheet-type adhesive. In the adhesive composition, the polyamide elastomer content was 15.7% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 47.0% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 37.1% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.16% by mass relative to the mass of the adhesive composition (solids excluding solvent). The obtained physical properties are as shown in Table 1. During the peel test, the state of failure was confirmed visually. In both the solution-type adhesive and the sheet-type adhesive, when peeling the copper foil from the polyimide film and polytetrafluoroethylene sheet substrates, the polyimide film interface and the polytetrafluoroethylene sheet interface were destroyed.

[0086] [Comparative Example 2]

[0087] This method differs from Example 1 in that it contains 0 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 20 parts by mass of "XD-1000" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, and 15.81 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, as an epoxy resin curing agent. However, all other conditions and methods were the same as in Example 1 to obtain a solution-type adhesive and a sheet-type adhesive. In the adhesive composition, the polyamide elastomer content was 0% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 55.8% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 44.1% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.14% by mass relative to the mass of the adhesive composition (solids excluding solvent). The obtained physical properties are as shown in Table 1. During the peel test, the state of failure was confirmed visually. In both the solution-type adhesive and the sheet-type adhesive, when peeling the copper foil from the polyimide film and polytetrafluoroethylene sheet substrates, the polyimide film interface and the polytetrafluoroethylene sheet interface were destroyed.

[0088] [Example 6]

[0089] This method differs from Example 1 in that it contains 15 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 5 parts by mass of "NC-3000-H" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, and 3.46 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, as an epoxy resin curing agent. However, all other conditions and methods were the same as in Example 1 to obtain a solution-type adhesive and a sheet-type adhesive. In the adhesive composition, the polyamide elastomer content was 63.8% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 21.3% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 14.7% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.21% by mass relative to the mass of the adhesive composition (solids excluding solvent). The obtained physical properties are shown in Table 1. During the peel test, the state of failure was confirmed visually. In both the solution-type adhesive and the sheet-type adhesive, the copper foil was damaged when peeled from the base material, which was a polyimide film or polytetrafluoroethylene sheet.

[0090] [Example 7]

[0091] This method differs from Example 1 in that it contains 15 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 5 parts by mass of "EPPN-502H" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, and 5.95 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, as an epoxy resin curing agent. However, all other conditions and methods were the same as in Example 1 to obtain a solution-type adhesive and a sheet-type adhesive. In the adhesive composition, the polyamide elastomer content was 57.7% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 19.2% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 22.9% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.19% by mass relative to the mass of the adhesive composition (solids excluding solvent). The obtained physical properties are as shown in Table 1. During the peel test, the state of failure was confirmed visually. In both the solution-type adhesive and the sheet-type adhesive, the copper foil was damaged when peeled from the base material, which was a polyimide film or polytetrafluoroethylene sheet.

[0092] [Example 8]

[0093] This method differs from Example 1 in that it contains 15 parts by mass of "TPAE-32" (manufactured by T&K TOKA Co., Ltd.) as a polyamide elastomer, 5 parts by mass of "NC-7000L" (manufactured by Nippon Kayaku Co., Ltd.) as an epoxy resin, and 4.31 parts by mass of "GPH-65" (manufactured by Nippon Kayaku Co., Ltd.), a phenolic curing agent, as an epoxy resin curing agent. However, all other conditions and methods were the same as in Example 1 to obtain a solution-type adhesive and a sheet-type adhesive. In the adhesive composition, the polyamide elastomer content was 61.6% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin content was 20.5% by mass relative to the mass of the adhesive composition (solids excluding solvent), the epoxy resin curing agent content was 17.7% by mass relative to the mass of the adhesive composition (solids excluding solvent), and the curing accelerator content was 0.21% by mass relative to the mass of the adhesive composition (solids excluding solvent). The obtained physical properties are as shown in Table 1. During the peel test, the state of failure was confirmed visually. In both the solution-type adhesive and the sheet-type adhesive, the copper foil was damaged when peeled from the base material, which was a polyimide film or polytetrafluoroethylene sheet.

[0094] The test results are shown in Table 1.

[0095] [Table 1]

[0096] The following can be seen from Table 1. Note that the units in Table 1 are parts by mass.

[0097] The adhesive compositions of Examples 1 to 8 all contained a polyamide elastomer, an epoxy resin, and an epoxy resin curing agent. The polyamide elastomer content was 17 to 99% by mass of the adhesive composition (solids excluding solvent), and the epoxy resin content was 3 to 46% by mass of the adhesive composition (solids excluding solvent). Therefore, the adhesive compositions of Examples 1 to 8 all exhibited excellent adhesion, with a peel strength of 10 N / mm or more when using polyimide film and polytetrafluoroethylene sheet as substrates, and also possessed low dielectric properties with a dielectric constant of 3.1 or less.

[0098] Comparative Example 1, in which the polyamide elastomer content was less than 17% by mass relative to the mass of the adhesive composition (solid content excluding solvent), and Comparative Example 2, which did not contain polyamide elastomer, both showed peel strengths of less than 10 N / mm when using polyimide film and polytetrafluoroethylene sheet as substrates, indicating poor adhesive properties.

[0099] Although embodiments and examples of this technology have been described in detail above, this technology is not limited to the embodiments and examples described above, and various modifications based on the technical concept of this technology are possible.

[0100] For example, the configurations, methods, processes, shapes, materials, and numerical values ​​mentioned in the above-described embodiments and examples are merely examples, and different configurations, methods, processes, shapes, materials, and numerical values ​​may be used as needed.

[0101] Furthermore, the configurations, methods, processes, shapes, materials, and numerical values ​​of the above-described embodiments and examples can be combined with each other, as long as they do not deviate from the spirit of this technology.

[0102] Furthermore, in this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described stepwise in this specification, the upper or lower limit of one step in the numerical range may be replaced with the upper or lower limit of another step in the numerical range. Unless otherwise specified, the materials exemplified in this specification may be used individually or in combination of two or more.

Claims

1. Polyamide elastomer and Epoxy resin and Epoxy resin hardener and A hardening accelerator, It contains, The polyamide elastomer content is 17 to 99% by mass relative to the mass of the adhesive composition (solid content excluding solvent), The epoxy resin content is 3 to 46% by mass relative to the mass of the adhesive composition (solid content excluding solvent). The epoxy resin curing agent content is 3 to 37% by mass relative to the mass of the adhesive composition (solid content excluding solvent). The content of the curing accelerator is 0.17 to 0.4% by mass relative to the mass of the adhesive composition (solid content excluding solvent). The polyamide elastomer is a polyether ester amide. The epoxy resin is selected from the group consisting of dicyclopentadiene-type epoxy resin, triphenylmethane-type epoxy resin, and novolac-type epoxy resin, The novolac-type epoxy resin is a biphenylene novolac-type epoxy resin and / or a naphthol-cresol novolac-type epoxy resin. The epoxy resin curing agent is a phenol-based curing agent. An adhesive composition wherein the curing accelerator is an imidazole-based curing accelerator.

2. The adhesive composition according to claim 1, wherein the polyamide elastomer is a solvent-soluble polyamide elastomer.

3. The adhesive composition according to claim 1, wherein the peel strength of the adhesive interface between the metal foil and the base resin when the metal foil and the base resin are bonded via the adhesive composition is 10 N / 10 mm or more, the base resin is polyimide or polytetrafluoroethylene, and the peel strength is the 90° peel strength measured by performing a tensile test in the 90° direction at a peeling speed of 300 mm / min in accordance with JIS Z0237.

4. The adhesive composition according to claim 1, wherein the dielectric constant is 3.1 or less.

5. A coverlay film having the adhesive composition described in claim 1 applied to at least one of its surfaces.

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