Polyimide resin, adhesive, and laminate using the same

Abstract

To provide a polymer which has good stability under high temperature and high humidity, reduces lowering of adhesive force over time, and has good dielectric characteristics, an adhesive and a laminate.SOLUTION: A polyimide resin has a sulfanyl group that is a reaction product of polyimide (A) containing residues derived from tetracarboxylic acid dianhydride or a tetracarboxylic acid (B) and dimer diamine (C), and a terminal modifier (D) having a sulfanyl group, at a terminal.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polyimide resin, and an adhesive and a laminate using the same. [Background technology]

[0002] In recent years, the electronics field has seen remarkable development, particularly in the miniaturization, weight reduction, and high density of electronic devices, which has led to an increasing demand for thinner, multi-layered, and highly precise electronic materials, such as printed wiring boards. Specific examples of adhesives and coating agents used in such electronic materials include the following (1) to (6):

[0003] (1) Interlayer adhesive: Used to bond circuit boards together, it comes into direct contact with the copper or silver circuit. It is used between the layers of multilayer boards and is available in liquid and sheet form.

[0004] (2) Adhesives for coverlay films: These are used to bond coverlay films (such as polyimide films used to protect the top surface of circuits) to the underlying circuit board, and many of them have the polyimide film and adhesive layer already integrated.

[0005] (3) Copper-clad film (CCL) adhesive: Used to bond polyimide film and copper foil. Etching and other processes are performed when forming the copper circuit.

[0006] (4) Coverlay: Used to protect the top surface of a circuit, it is formed by printing on the circuit (printed coverlay) or by laminating an adhesive sheet (film coverlay) and then curing it with light (photosensitive coverlay) or heat.

[0007] (5) Reinforcing plate adhesive: Used to fix part of a wiring board to a reinforcing plate made of metal, glass epoxy, polyimide, etc., in order to supplement the mechanical strength of the wiring board.

[0008] (6) Electromagnetic wave shield: It mainly consists of an adhesive conductive layer and an insulating layer, and is attached to a flexible printed wiring board to block electromagnetic noise generated from electronic circuits.

[0009] These may be in the form of a liquid (made into ink for printing) or a sheet (pre-formed into a film), and the appropriate form is selected depending on the application.

[0010] In order to meet these high demands for peripheral electronic components, various polyimide resins are being investigated.

[0011] On the other hand, polyimide resins have low solvent solubility, making them difficult to handle. In recent years, efforts have been made to develop polyimide resins that have good solvent solubility and dielectric properties.

[0012] For example, Patent Document 1 discloses that polyimides with good solvent solubility and dielectric properties can be synthesized by incorporating dimer diamine into polyimides. However, although the polyimides described in Patent Document 1 have a high thermal decomposition temperature, they do not have sufficient structural stability under high temperatures or high humidity, and there is a problem with maintaining adhesive strength over time.

[0013] In addition, Patent Document 2 discloses a method for producing a soft polymer by combining a dimer diamine and a phenylenediamine skeleton. It is disclosed that the melting point is improved. However, even in the invention described in Patent Document 2, stability under high temperature and high humidity conditions is insufficient, and there is a problem in maintaining adhesive strength over time. In addition, there is a problem in that the phenylenediamine skeleton strengthens the interaction between polyimides, resulting in a deterioration in specific physical properties such as dielectric properties. [Prior art documents] [Patent documents]

[0014] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-168369 [Patent Document 2] Japanese Patent Application Publication No. 2020-117631 Summary of the Invention [Problem to be solved by the invention]

[0015] The problem to be solved by the present invention is to provide a polyimide resin that has good stability at high temperatures and high humidity, exhibits little decrease in adhesion over time, and has good dielectric properties, as well as an adhesive and a laminate using the same. [Means for solving the problem]

[0016] The present invention relates to the following inventions [1] to [7].

[0017] [1] A polyimide resin having a sulfanyl group at its terminal, which is a reaction product of a polyimide (A) containing a residue derived from a tetracarboxylic dianhydride or tetracarboxylic acid (B) and a dimer diamine (C) and a terminal modifier (D) having a sulfanyl group. [2] The polyimide resin according to [1], wherein the tetracarboxylic dianhydride or tetracarboxylic acid (B) has an alicyclic structure. [3] The polyimide resin according to [1] or [2], wherein the polyimide (A) further contains a residue derived from an aromatic diamine (excluding diamines having a phenol skeleton) and / or a diamine having a phenol skeleton. [4] An adhesive comprising the polyimide resin according to any one of [1] to [3] and a crosslinking agent and / or a curing accelerator. [5] A laminate having an adhesive layer containing the adhesive according to [4] and a substrate. [6] The laminate according to [5], wherein the substrate comprises a copper foil and / or an insulating layer. [7] The laminate according to [5] or [6], which is for use in a printed wiring board. [Effects of the Invention]

[0018] The present invention can provide a polyimide resin, adhesive, and laminate that are stable under high temperature and high humidity conditions, exhibit little deterioration in adhesion over time, and have good dielectric properties. DETAILED DESCRIPTION OF THE INVENTION

[0019] The following describes in detail the embodiments of the present invention. However, the description of the constituent elements described below is an example (representative example) of an embodiment of the present invention, and the present invention is not limited to these contents as long as it does not exceed the gist of the present invention.

[0020] In this specification, a numerical range specified using "to" is intended to include the numerical values before and after "to" as the range's lower and upper limits. Unless otherwise noted, the various components appearing in this specification may be used independently either alone or in combination of two or more.

[0021] In this specification, the number average molecular weight (Mn) and weight average molecular weight (Mw) are values measured by gel permeation chromatography (GPC) in terms of polystyrene. The glass transition temperature is a value measured by a differential scanning calorimeter. Details are described in the Examples section.

[0022] <Polyimide resin having sulfanyl groups at the terminals> The polyimide resin having a sulfanyl group at its terminal (hereinafter sometimes abbreviated as polyimide resin) used in the present invention is a reaction product of a polyimide (A) containing residues derived from a tetracarboxylic dianhydride (B) and a dimer diamine (C) and a terminal modifier (D) having a sulfanyl group. While the synthesis method is not particularly limited, the polyimide can be obtained by reacting an acid anhydride or amino group, which is the terminal functional group of the polyimide (A), with an amino group or a carboxyl group contained in the terminal modifier (D) having a sulfanyl group. From the viewpoint of synthesis method, the reaction of a polyimide (A) whose terminal functional group is an acid anhydride group with a terminal modifier containing an amino group is preferred, and a block polymer having strong linkages containing imide or amide bonds can be obtained by a simple synthesis method. From the viewpoint of dielectric properties and coatability, the number average molecular weight (Mn) of the polyimide resin is preferably 2,000 to 100,000. A number average molecular weight of 2,000 or more provides better dielectric properties, while a number average molecular weight of 100,000 or less provides better coatability. From the viewpoint of dielectric properties and coatability, the mass average molecular weight (Mw) of the polyimide resin is preferably 5,000 to 200,000. A mass average molecular weight of 5,000 or more provides better dielectric properties, while a mass average molecular weight of 200,000 or less provides better coatability. From the viewpoint of adhesive strength and heat resistance, the glass transition temperature (hereinafter sometimes referred to as Tg) of the polyimide resin is preferably 10 to 100° C. A Tg of 10° C. or higher provides better stability under high temperature and high humidity conditions, while a Tg of 100° C. or lower provides better adhesive strength.

[0023] <Polyimide (A)> The polyimide (A) contains residues derived from a tetracarboxylic dianhydride or tetracarboxylic acid (B) and a dimer diamine (C), and preferably further contains residues derived from an aromatic diamine (excluding diamines having a phenol skeleton) and / or a diamine having a phenol skeleton.

[0024] The polyimide (A) can be obtained, for example, by reacting a tetracarboxylic dianhydride with a diamine compound containing dimer diamine. The reaction between the tetracarboxylic dianhydride and the diamine compound can be carried out by a known method. Examples of solvents used in the reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), diethylene glycol diethyl ether, cyclohexanone, 1,4-dioxane, toluene, xylene, mesitylene, and solvent naphtha.

[0025] <Tetracarboxylic acid dianhydride or tetracarboxylic acid (B)> Examples of the tetracarboxylic dianhydride (B) include 3,3',4,4'-biphenyltetracarboxylic dianhydride, 2,3,3',4'-biphenyltetracarboxylic dianhydride, 3,3',4,4'-diphenylsulfonetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-diphenylethertetracarboxylic dianhydride, 4,4'-[propane-2,2-diylbis(1,4-phenyleneoxy)]diphthalic dianhydride, 2,2-bis(3,3',4,4'-tetracarboxyphenyl)tetrafluoropropane dianhydride, 2,2-bis(3,4-dicarboxyphenyl)propane dianhydride, 2,2'-bis(3,4-dicarboxyphenoxyphenyl)sulfone dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, 2,2-bis(2,3 -dicarboxyphenyl)propane dianhydride, pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 9,9'-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, 9,9'-bis(3,4-dicarboxyphenoxy)fluorene dianhydride anhydride, 1',2'-dianhydride; 4,4'-[4,4'-(propane-2,2-diyl)diphenoxy]diphthalic dianhydride, 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-C]furan-1,3-dione, 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic acid anhydride, and the like. Examples of the tetracarboxylic acid include structures obtained by hydrolysis of the tetracarboxylic dianhydrides to form dicarboxylic acids. These tetracarboxylic dianhydrides or tetracarboxylic acids which are hydrolysates thereof can be used alone or in combination of two or more kinds.

[0026] From the viewpoints of compatibility with diamines, adhesiveness, and heat resistance, the tetracarboxylic dianhydride is preferably a tetracarboxylic dianhydride having an aromatic ring adjacent to an acid anhydride group, or a tetracarboxylic dianhydride having an alicyclic structure. The tetracarboxylic acid dianhydride having an aromatic ring adjacent to the acid anhydride group preferably includes at least one selected from the group consisting of 2,2-bis(3,3',4,4'-tetracarboxyphenyl)tetrafluoropropane dianhydride, 9,9'-bis[4-(3,4-dicarboxyphenoxy)phenyl]fluorene dianhydride, 1',2'-dianhydride; 4,4'-[4,4'-(propane-2,2-diyl)diphenoxy]diphthalic dianhydride, 3,3',4,4'-biphenyltetracarboxylic acid dianhydride, and 2,3,3',4'-biphenyltetracarboxylic acid dianhydride. Examples of tetracarboxylic dianhydrides having an alicyclic structure include 1,2,3,4-cyclobutanetetracarboxylic dianhydride, 2,3,5-tricarboxycyclopentylacetic dianhydride, 1,3,3a,4,5,9b-hexahydro-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 1,3,3a,4,5,9b-hexahydro-8-methyl-5-(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]furan-1,3-dione, 3-oxabicyclo[3.2.1]octane-2,4-dione-6-spiro-3'tetrahydrofuran-2',5'-dione, and 5-(2,5-dioxotetrahydro-3-furanyl) and 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride. From the viewpoint of moisture resistance and heat resistance, tetracarboxylic dianhydrides having an alicyclic structure are particularly preferred. Note that when a tetracarboxylic dianhydride in which an aromatic ring is adjacent to an acid anhydride group has an alicyclic structure in the molecule, it is classified as a tetracarboxylic dianhydride in which an aromatic ring is adjacent to an acid anhydride group.

[0027] The content of the tetracarboxylic dianhydride or the tetracarboxylic acid (B) having an alicyclic structure is preferably 30 to 100% by mass, more preferably 50 to 100% by mass. By being within the above range, excellent dielectric properties are achieved.

[0028] <Dimer diamine (C)> In this specification, the dimer diamine (C) refers to a cyclic or acyclic dicarboxylic acid, which is a dimer of an unsaturated fatty acid, in which all the carboxyl groups have been substituted with primary amino groups. Commercially available dimer diamine products include, for example, "Priamine 1071," "Priamine 1073," "Priamine 1074," and "Priamine 1075" manufactured by Croda Japan, and "Versamin 551" manufactured by BASF Japan. The dimer diamines can be used alone or in combination of two or more.

[0029] The content of the dimer diamine (C) in all diamine compounds is preferably 40 to 100 mass %, more preferably 60 to 100 mass % or less. By being in the above range, a polyimide resin excellent in dielectric properties and adhesiveness can be obtained.

[0030] <Other diamines> The polyimide (A) may contain a residue derived from a diamine other than the dimer diamine (C). Examples of diamines other than the dimer diamine include, but are not limited to, diamine compounds having the following structures. In particular, aromatic diamines (excluding diamines having a phenol skeleton) and diamines having a phenol skeleton are preferred from the viewpoint of heat resistance.

[0031] [ka]

[0032] [ka] (l is an integer between 1 and 3)

[0033] [ka]

[0034] [ka]

[0035] [ka]

[0036] When an aromatic diamine (excluding phenolic skeleton-containing diamines) or a phenolic skeleton-containing diamine is contained, the content thereof is preferably 0.1 to 60 mass % of the total diamine compounds, and more preferably 0.3 to 50 mass % or less. By being within the above range, a polyimide resin excellent in heat resistance and adhesiveness can be obtained.

[0037] <Terminal Modifier Having a Sulfanyl Group (D)> The sulfanyl-containing terminal-modifying agent (D) is used to modify the terminals of the polyimide (A) with sulfanyl groups to obtain a polyimide resin having sulfanyl groups at the terminals. When the terminals of the polyimide (A) are acid anhydride groups, it is preferable to use the amino-containing terminal-modifying agent (D1), and when the terminals of the polyimide (A) are amino groups, it is preferable to use the carboxyl-containing terminal-modifying agent (D2). Examples of the terminal modifying agent (D1) having an amino group include, but are not limited to, aliphatic amines having a sulfanyl group, such as aminoalkanethiols, such as 2-aminoethanethiol, 3-aminopropyl-1-thiol, 1-aminopropyl-2-thiol, and 4-amino-1-butanethiol; aromatic amines having a sulfanyl group, such as aminobenzenethiols, such as 2-aminobenzenethiol, 3-aminobenzenethiol, and 4-aminobenzenethiol; and cysteine. Examples of the terminal modifier (D2) having a carboxyl group include, but are not limited to, carboxylic acids having a sulfanyl group, such as 3-mercaptopropionic acid, 2-mercaptopropionic acid, 6,8-dimercapto-n-octanoic acid, 3-mercapto-2-methylpropionic acid, and mercaptoacetic acid. From the viewpoint of synthesis method, it is preferable to use a terminal modifier (D1) having an amino group, and among them, from the viewpoint of improving adhesion, aminobenzenethiol and aminoalkanethiol are preferred, and 2-aminoethanethiol is particularly preferred. Two or more types of terminal modifying agents (D1) having an amino group or two or more types of terminal modifying agents (D2) having a carboxyl group may be used.

[0038] The sulfanyl group-containing terminal modifier (D) is preferably contained so that the molar equivalent ratio between the terminal functional groups of the polyimide (A) and the functional groups of the terminal modifier (D) is 0.1 to 1.5, more preferably 0.8 to 1.0. By keeping the ratio within the above range, a polyimide resin with excellent heat resistance and moisture resistance can be obtained.

[0039] The reaction of the polyimide (A) with the sulfanyl group-containing terminal modifier can be carried out by a known method. Examples of solvents used in the reaction include N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), diethylene glycol diethyl ether, cyclohexanone, 1,4-dioxane, toluene, xylene, mesitylene, and solvent naphtha.

[0040] <Adhesive> The adhesive of the present invention comprises a polyimide resin having a sulfanyl group at its terminal, and a crosslinking agent and / or a curing accelerator.

[0041] <Crosslinking agent> Examples of the crosslinking agent include a compound containing an ethylenically unsaturated bond, an epoxy group-containing compound, an isocyanate group-containing compound, a benzoxazine resin, a bismaleimide resin, and a cyanate ester resin.

[0042] (Compounds containing ethylenically unsaturated bonds) The compound containing an ethylenically unsaturated bond is not particularly limited as long as it has an ethylenically unsaturated bond in the molecule, but it is preferable to use a compound having an average of two or more ethylenically unsaturated bonds in one molecule. For example, methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, butyl acrylate, isoamyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, decyl acrylate, lauryl acrylate, stearyl acrylate, isobornyl acrylate, cyclohexyl acrylate, dicyclopentenyl acrylate, dicyclopentenyloxyethyl acrylate, benzyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxy-3-chloropropyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy-3-allyloxypropyl acrylate, 2-acryloyloxyethyl-2-hydroxypropyl phthalate, 2,2,2-trifluoroethyl acrylate, 2,2,3,3-tetrafluoropropyl acrylate, 1H-hexafluoroisopropyl acrylate, 1H,1H,5H-octafluoropentyl acrylate, 1H,1H,2H,2H-heptadecafluorodecyl acrylate, 2,6-dibromo-4-butylphenyl acrylate, 2,4,6-tribromophenoxyethyl acrylate, 2,4,6-tribromophenol 3EO adduct acrylate, 2-methyloxyethyl acrylate, 1,3-butylene glycol methyl ether acrylate, butyloxyethyl acrylate, methyloxytriethylene glycol acrylate, methyloxypolyethylene glycol #400 acrylate, methyloxydipropylene glycol acrylate, methyloxytripropylene glycol acrylate, methyloxypolypropylene glycol acrylate, ethyloxydiethylene glycol acrylate, ethyl carbitol acrylate, 2-ethylhexyl carbitol acrylate, tetrahydrofurfuryl acrylate, phenoxyethyl acrylate, phenoxydiethylene glycol acrylate, phenoxypolyethylene glycol Acrylic acrylate, cresyl polyethylene glycol acrylate, p-nonylphenoxyethyl acrylate, p-nonylphenoxy polyethylene glycol acrylate, glycidyl acrylate, β-carboxyethyl acrylate, succinic acid monoacryloyloxyethyl ester, ω-carboxypolycaprolactone monoacrylate, 2-acryloyloxyethyl hydrogen phthalate, 2-acryloyloxypropyl hydrogen phthalate, 2-acryloyloxypropyl hexahydrohydrogen phthalate, 2-acryloyloxypropyl tetrahydrohydrogen phthalate, N,N-dimethylaminoethyl acrylate, N,N-dimethylaminopropyl acrylate, morpholinoethyl acrylate, trimethylsiloxyethyl acrylate, diphenyl-2-acryloyloxyethyl phosphate, 2-acryloyloxyethyl acid phosphate, caprolactone-modified-2-acryloyloxyethyl acid phosphate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, isopropyl methacrylate, butyl methacrylate, isoamyl methacrylate, hexyl methacrylate, 2-hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, decyl methacrylate, lauryl methacrylate, stearyl methacrylate, isobornyl methacrylate, cyclohexyl methacrylate, dicyclopentenyl methacrylate, dicyclopentenyloxyethyl methacrylate, benzyl methacrylate, 2 -Hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, 2-hydroxy-3-chloropropyl methacrylate, 2-hydroxy-3-phenoxypropyl methacrylate, 2-hydroxy-3-allyloxypropyl methacrylate, 2-methacryloyloxyethyl-2-hydroxypropyl phthalate, 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 1H-hexafluoroisopropyl methacrylate, 1H,1H,5H-octafluoropentyl methacrylate, 1H,1H,2H,2H-heptadecafluorodecyl methacrylate, 2,6-dibromo-4-butylphenyl methacrylate, 2,4,6-tribromophenoxyethyl methacrylate, 2,4,6-tribromophenol 3EO adduct methacrylate, 2-methyloxyethyl methacrylate, 1,3-Butylene glycol methyl ether methacrylate, butyloxyethyl methacrylate, methyloxytriethylene glycol methacrylate, methyloxypolyethylene glycol #400 methacrylate, methyloxydipropylene glycol methacrylate, methyloxytripropylene glycol methacrylate, methyloxypolypropylene glycol methacrylate, ethyloxydiethylene glycol methacrylate, 2-ethylhexyl carbitol methacrylate, tetrahydrofurfuryl methacrylate, phenoxyethyl methacrylate, phenoxydiethylene glycol methacrylate, phenoxypolyethylene glycol methacrylate, cresyl polyethylene glycol methacrylate, p-nonylphenoxyethyl methacrylate, p-nonylphenoxypolyethylene glycol methacrylate, glycidyl methacrylate, dimethylaminomethyl methacrylate, N,N-dimethylaminoethyl methacrylate, N,N-dimethylaminopropyl methacrylate, methylsiloxyethyl methacrylate, trimethylsiloxyethyl methacrylate, diphenyl-2-methacryloyloxyethyl phosphate, 2-methacryloyloxyethyl acid phosphate, caprolactone-modified-2-methacryloyloxyethyl acid phosphate, allyl glycidyl ether, acrylamide, N-methylolacrylamide, diacetone acrylamide, N,N-dimethylacrylamide, N,N-diethylacrylamide, N-isopropylacrylamide, acryloylmorpholine, methacrylamide, N-methylolmethacrylamide, diacetone methacrylamide, N,N-dimethylmethacrylamide, N,N-diethylmethacrylamide, N-isopropylmethacrylamide, methacryloylmorpholine, styrene, p-hydroxystyrene, p-chlorostyrene, p-bromostyrene, p-methylstyrene, p-methyloxystyrene, pt-butyloxystyrene, pt-butyloxycarbonylstyrene, pt-butyloxycarbonyloxystyrene, 2,4-Diphenyl-4-methyl-1-pentene, vinyl acetate, vinyl monochloroacetate, vinyl benzoate, vinyl pivalate, vinyl butyrate, vinyl laurate, vinyl methacrylate, vinyl crotonate, vinyl 2-ethylhexanoate, N-vinylcarbazole, N-vinylpyrrolidone, 1,4-butanediol diacrylate, 1,6-hexanediol diacrylate, ethylene glycol diacrylate, diethylene glycol diacrylate, triethylene glycol diacrylate, tetraethylene glycol diacrylate, polyethylene glycol #200 diacrylate, polyethylene glycol #300 diacrylate, polyethylene glycol #400 diacrylate, polyethylene glycol #600 diacrylate, dipropylene glycol diacrylate, tripropylene glycol diacrylate, tetrapropylene glycol diacrylate, polypropylene glycol #400 diacrylate, polypropylene glycol #700 diacrylate, neopentyl glycol diacrylate, neopentyl glycol PO-modified diacrylate, hydroxy Pivalic acid neopentyl glycol ester diacrylate, caprolactone adduct diacrylate of hydroxypivalic acid neopentyl glycol ester, 1,6-hexanediol bis(2-hydroxy-3-acryloyloxypropyl) ether, bis(4-acryloxypolyethoxyphenyl)propane, 1,9-nonanediol diacrylate, pentaerythritol diacrylate, pentaerythritol diacrylate monostearate, pentaerythritol diacrylate monobenzoate, bisphenol A diacrylate, EO-modified bisphenol A diacrylate, PO-modified bisphenol A diacrylate, hydrogenated bisphenol A diacrylate, EO-modified hydrogenated bisphenol A diacrylate, PO-modified hydrogenated bisphenol A diacrylate, bisphenol F diacrylate, EO-modified bisphenol F diacrylate, PO-modified bisphenol F diacrylate, EO-modified tetrabromobisphenol A diacrylate, tricyclodecane dimethylol diacrylate, isocyanuric acid EO-modified diacrylate, 2-hydroxy-1,3-Diacryloxypropane, Glycerin PO-modified Triacrylate, Trimethylolpropane Triacrylate, Trimethylolpropane EO-modified Triacrylate, Trimethylolpropane PO-modified Triacrylate, Isocyanuric Acid EO-modified Triacrylate, Isocyanuric Acid EO-modified ε-caprolactone-modified Triacrylate, 1,3,5-Triacryloylhexahydro-s-triazine, Pentaerythritol Triacrylate, Dipentaerythritol Triacrylate Tripropionate, Pentaerythritol Tetraacrylate Acrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate monopropionate, dipentaerythritol hexaacrylate, tetramethylolmethane tetraacrylate, oligoester tetraacrylate, tris(acryloyloxy)phosphate, 1,4-butanediol dimethacrylate, 1,6-hexanediol dimethacrylate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol Licorice dimethacrylate, polyethylene glycol #200 dimethacrylate, polyethylene glycol #300 dimethacrylate, polyethylene glycol #400 dimethacrylate, polyethylene glycol #600 dimethacrylate, dipropylene glycol dimethacrylate, tripropylene glycol dimethacrylate, tetrapropylene glycol dimethacrylate, polypropylene glycol #400 dimethacrylate, polypropylene glycol #700 dimethacrylate, neopentyl glycol dimethacrylate, neopentyl glycol PO-modified dimethacrylate, hydroxypivalic acid neopentyl glycol ester dimethacrylate, hydroxypivalic acid neopentyl glycol ester caprolactone adduct dimethacrylate, 1,6-hexanediol bis(2-hydroxy-3-methacryloyloxypropyl) ether, 1,9-nonanediol dimethacrylate, pentaerythritol dimethacrylate, pentaerythritol dimethacrylate monostearate, pentaerythritol dimethacrylate monobenzoate, 2,2-bis(4-methacryloxypolyethoxyphenyl)propane, bisphenol A dimethacrylate, EO-modified bisphenol A dimethacrylate, PO-modified bisphenol A dimethacrylate, hydrogenated bisphenol A dimethacrylate, EO-modified hydrogenated bisphenol A dimethacrylate, PO-modified hydrogenated bisphenol A dimethacrylate, bisphenol F dimethacrylate, EO-modified bisphenol F dimethacrylate, PO-modified bisphenol F dimethacrylate, EO-modified tetrabromobisphenol A dimethacrylate, tricyclodecane dimethylol dimethacrylate, isocyanuric acid EO-modified dimethacrylate, 2-hydroxy-1,3-dimethacryloxypropane, glycerin PO, Modified trimethacrylate, trimethylolethane trimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane EO-modified trimethacrylate, trimethylolpropane PO-modified trimethacrylate, isocyanuric acid EO-modified trimethacrylate, isocyanuric acid EO-modified ε-caprolactone-modified trimethacrylate, 1,3,5-trimethacryloylhexahydro-s-triazine, pentaerythritol trimethacrylate, dipentaerythritol trimethacrylate Acrylate tripropionate, pentaerythritol tetramethacrylate, dipentaerythritol pentamethacrylate monopropionate, dipentaerythritol hexamethacrylate, tetramethylolmethane tetramethacrylate, oligoester tetramethacrylate, tris(methacryloyloxy)phosphate, triallyl isocyanurate, triallyl cyanurate, diallyl maleate, diallyl fumarate, diallyl adipate, diallyl phthalate, tetraallyl Pyromellitate, glycerin diallyl ether, trimethylolpropane diallyl ether, pentaerythritol diallyl ether, pentaerythritol triallyl ether, pentaerythritol tetraallyl ether, dipentaerythritol pentaallyl ether, dipentaerythritol hexaallyl ether, sorbitol diallyl ether, ethylene glycol divinyl ether, diethylene glycol divinyl ether, triethylene glycol divinyl ether, tetraethylene glycol divinyl ether, pentaerythritol divinyl ether, propylene glycol divinyl ether, dipropylene glycol divinyl ether, tripropylene glycol divinyl ether, neopentyl glycol divinyl ether, 1,4-butanediol divinyl ether, 1,6-hexanediol divinyl ether, glycerin divinyl ether, trimethylolpropane divinyl ether, 1,4-dihydroxycyclohexane divinyl ether, 1,Examples of the vinyl vinyl ether include 4-dihydroxymethylcyclohexane divinyl ether, hydroquinone divinyl ether, ethylene oxide-modified hydroquinone divinyl ether, ethylene oxide-modified resorcinol divinyl ether, ethylene oxide-modified bisphenol A divinyl ether, ethylene oxide-modified bisphenol S divinyl ether, glycerin trivinyl ether, sorbitol tetravinyl ether, trimethylolpropane trivinyl ether, pentaerythritol trivinyl ether, pentaerythritol tetravinyl ether, dipentaerythritol hexavinyl ether, dipentaerythritol polyvinyl ether, ditrimethylolpropane tetravinyl ether, and ditrimethylolpropane polyvinyl ether.

[0043] (Epoxy group-containing compound) The epoxy group-containing compound is not particularly limited as long as it has an epoxy group in the molecule, but a compound having an average of two or more epoxy groups in one molecule can be preferably used. Examples of the epoxy group-containing compound include epoxy resins such as glycidyl ether epoxy resins, glycidyl amine epoxy resins, glycidyl ester epoxy resins, and cyclic aliphatic (alicyclic) epoxy resins.

[0044] Examples of glycidyl ether type epoxy resins include cresol novolac type epoxy resins, phenol novolac type epoxy resins, and tetrakis(glycidyloxyphenyl)ethane. Examples of suitable epoxy resins include tetraglycidyl diaminodiphenylmethane, tetraglycidyl metaxylylenediamine, 1,2,4-benzenetricarboxylic acid triglycidyl ester, 1,3,5-benzenetricarboxylic acid triglycidyl ester, 1,1,2,4,5-benzenetetracarboxylic acid tetraglycidyl ester, tri(carboxyethyl)isocyanurate triglycidyl ester, and polyglycidyl esters derived from polycarboxylic acids such as polymerized fatty acids. Examples of suitable epoxy resins include cyclohexane-1,2,4-tricarboxylic acid triglycidyl ester, 1,2,4-cyclohexanetricarboxylic acid triglycidyl ester, 1,3,5-cyclohexanetricarboxylic acid triglycidyl ester, 2,4,5-cyclohexanetetracarboxylic acid tetraglycidyl ester, bisphenol A epoxy resin, bisphenol F epoxy resin, and dicyclopentadiene epoxy resin. Examples of suitable epoxy resins include diglycidyl phthalate, diglycidyl hexahydrophthalate, or diglycidyl tetrahydrophthalate, and 3',4'-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate.

[0045] (Isocyanate group-containing compounds) The isocyanate group-containing compound is not particularly limited as long as it has an isocyanate group in the molecule. Specific examples of the isocyanate group-containing compound having one isocyanate group per molecule include n-butyl isocyanate, isopropyl isocyanate, phenyl isocyanate, benzyl isocyanate, (meth)acryloyloxyethyl isocyanate, 1,1-bis[(meth)acryloyloxymethyl]ethyl isocyanate, vinyl isocyanate, allyl isocyanate, (meth)acryloyl isocyanate, and isopropenyl-α,α-dimethylbenzyl isocyanate. Also, 1,6-diisocyanatohexane, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate, polymeric diphenylmethane diisocyanate, xylylene diisocyanate, 2,4-tolylene diisocyanate, toluene diisocyanate, 2,4-toluene diisocyanate, hexamethylene diisocyanate, 4-methyl-m-phenylene diisocyanate, naphthylene diisocyanate, paraphenylene diisocyanate, tetramethylxylylene diisocyanate, cyclohexylmethane diisocyanate, hydrogenated Compounds obtained by reacting equimolar amounts of diisocyanate compounds such as xylylene diisocyanate, cyclohexyl diisocyanate, tolidine diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, m-tetramethylxylylene diisocyanate, p-tetramethylxylylene diisocyanate, and dimer acid diisocyanate with hydroxyl group-, carboxyl group-, or amide group-containing vinyl monomers can also be used as the isocyanate compound.

[0046] Specific examples of the isocyanate group-containing compound having two isocyanate groups in one molecule include aromatic diisocyanates such as 1,3-phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,4-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-toluidine diisocyanate, 2,4,6-triisocyanate toluene, 1,3,5-triisocyanate benzene, dianisidine diisocyanate, 4,4'-diphenyl ether diisocyanate, and 4,4',4"-triphenylmethane triisocyanate; Aliphatic diisocyanates such as trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate; aromatic aliphatic diisocyanates such as ω,ω'-diisocyanate-1,3-dimethylbenzene, ω,ω'-diisocyanate-1,4-dimethylbenzene, ω,ω'-diisocyanate-1,4-diethylbenzene, 1,4-tetramethylxylylene diisocyanate, and 1,3-tetramethylxylylene diisocyanate; Examples of the diisocyanate include alicyclic diisocyanates such as 3-isocyanatemethyl-3,5,5-trimethylcyclohexyl isocyanate (also known as isophorone diisocyanate), 1,3-cyclopentane diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 4,4'-methylenebis(cyclohexyl isocyanate), 1,3-bis(isocyanatemethyl)cyclohexane, and 1,4-bis(isocyanatemethyl)cyclohexane.

[0047] Specific examples of the isocyanate group-containing compound having three isocyanate groups in one molecule include aromatic polyisocyanates, aliphatic polyisocyanates such as lysine triisocyanate, aromatic aliphatic polyisocyanates, and alicyclic polyisocyanates, as well as the trimethylolpropane adducts of the diisocyanates described above, biuret products obtained by reaction with water, and trimers having an isocyanurate ring.

[0048] As the isocyanate group-containing compound, a blocked isocyanate group-containing compound in which the isocyanate group in the various isocyanate group-containing compounds exemplified above is protected with ε-caprolactam, methyl ethyl ketone (hereinafter, referred to as MEK) oxime, or the like can also be used. Specific examples include compounds in which the isocyanate group of the isocyanate group-containing compound is blocked with ε-caprolactam, MEK oxime, cyclohexanone oxime, pyrazole, phenol, etc. In particular, hexamethylene diisocyanate trimer, which has an isocyanurate ring and is blocked with MEK oxime or pyrazole, is highly preferred in the present invention because it has excellent adhesive strength and heat resistance to polyimide and copper.

[0049] (benzoxazine resin) Examples of benzoxazine resins include 6,6-(1-methylethylidene)bis(3,4-dihydro-3-phenyl-2H-1,3-benzoxazine) and 6,6-(1-methylethylidene)bis(3,4-dihydro-3-methyl-2H-1,3-benzoxazine). A phenyl group, a methyl group, a cyclohexyl group, or the like may be bonded to the nitrogen of the oxazine ring. Commercially available products include "Benzoxazine Fa Type" and "Benzoxazine Pd Type" manufactured by Shikoku Chemicals Corporation, and "RLV-100" manufactured by Air Water Inc., and two or more of these may be used in combination.

[0050] (bismaleimide resin) Examples of bismaleimide resins include 4,4'-diphenylmethane bismaleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6'-bismaleimide-(2,2,4-trimethyl)hexane, 4,4'-diphenyl ether bismaleimide, 4,4'-diphenylsulfone bismaleimide, etc. Commercially available products include, for example, "BAF-BMI" manufactured by JFE Chemical Corporation, and two or more of these may be used in combination.

[0051] (cyanate ester resin) Examples of cyanate ester resins include 2-allylphenol cyanate ester, 4-methoxyphenol cyanate ester, 2,2-bis(4-cyanatophenol)-1,1,1,3,3,3-hexafluoropropane, bisphenol A cyanate ester, diallylbisphenol A cyanate ester, 4-phenylphenol cyanate ester, 1,1,1-tris(4-cyanatophenyl)ethane, 4-cumylphenol cyanate ester, 1,1-bis(4-cyanatophenyl)ethane, 4,4'-bisphenol cyanate ester, and 2,2-bis(4-cyanatophenyl)propane. Two or more of these may be used in combination.

[0052] From the viewpoint of moldability, durability, and adhesiveness, the content of the crosslinking agent is preferably 0.1 to 30 parts by mass, more preferably 0.5 to 5 parts by mass, per 100 parts by mass of the polyimide resin having a sulfanyl group at its end.

[0053] <Curing accelerator> The curing accelerator is preferably an amine catalyst or a radical-generating compound. Examples of the amine catalyst include non-reactive monoamines such as dimethylcyclohexylamine, N-methyldicyclohexylamine, triethylamine, tripropylamine, tributylamine, N-methylmorpholine, N-ethylmorpholine, and N-dimethylbenzylamine, non-reactive diamines such as triethylenediamine, tetramethylhexamethylenediamine, bisdimethylaminoethyl ether, tetramethylpropanediamine, dimethylaminoethylmorpholine, tetramethylethylenediamine, diazobicycloundecene, and 2-methyl-1,4-diazo[2.2.2]bicyclooctane, non-reactive triamines such as pentamethyldiethylenetriamine and pentamethyldipropylenetriamine, and reactive amines such as dimethylethanolamine, N-trioxyethylene-N,N-dimethylamine, and N,N-dimethyl-N-hexanolamine. Radical-generating compounds include organic peroxides such as benzoyl peroxide, tert-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di(2-ethoxyethyl) peroxydicarbonate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, and diacetyl peroxide, as well as 2,2 Examples of the azo compounds include 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl 2,2'-azobis(2-methylpropionate), 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-hydroxymethylpropionitrile), and 2,2'-azobis[2-(2-imidazolin-2-yl)propane]. These compounds may be used alone or in combination of two or more.

[0054] From the viewpoint of curability, durability, and adhesiveness, the content of the curing accelerator is preferably 0.5 to 30 parts by mass, and more preferably 0.5 to 10 parts by mass, per 100 parts by mass of the polyimide resin having a sulfanyl group at its end. In addition, from the viewpoints of durability, adhesion, and curability, it is preferable to use a crosslinking agent and a curing accelerator in combination.

[0055] <Organic solvents> The adhesive of the present invention may further contain an organic solvent. Examples of organic solvents include, but are not limited to, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, propyl acetate, toluene, xylene, anisole, N,N-dimethylformamide, N,N-dimethylacetamide, N-methylpyrrolidone, N-vinylpyrrolidone, N-methylcaprolactam, dimethyl sulfoxide, tetramethylurea, pyridine, dimethyl sulfone, hexamethyl sulfoxide, m-cresol, γ-butyrolactone, and γ-valerolactone. These solvents may be used alone or in combination.

[0056] <Other additives> The adhesive of the present invention may contain other additives as needed, such as fillers, flame retardants, antioxidants, ultraviolet absorbers, hydrolysis inhibitors, antifungal agents, thickeners, plasticizers, pigments, and bulking agents, and may also contain known catalysts and the like to adjust the curing reaction.

[0057] <Laminate> The laminate of the present invention has an adhesive layer made of the adhesive of the present invention and a substrate. For example, an adhesive layer formed of the adhesive of the present invention is formed on a first substrate, or a second substrate is further laminated on the adhesive layer. The substrate is not particularly limited and may be, for example, sheet-shaped or plate-shaped, and may include conventionally known plastic films, metal foils, etc. When two substrates are used, they may be the same or different. The thickness of the adhesive layer is preferably about 3 μm or more and 40 μm or less.

[0058] The laminate of the present invention can also be obtained by impregnating a fiber substrate with an adhesive, semi-curing (B-stage) it by heating or the like, and then laminating and curing it onto a metal foil or plastic film. As the fiber substrate, well-known materials used in various laminates for electrical insulating materials can be used. Examples of materials include inorganic fibers such as E-glass, S-glass, low-dielectric glass, and Q-glass; organic fibers such as low-dielectric glass polyimide, polyester, and tetrafluoroethylene; and mixtures thereof. In particular, inorganic fibers are preferred from the viewpoint of dielectric properties, and low-dielectric glass and Q-glass are more preferred. In the laminate of the present invention, when the adhesive is impregnated into a fiber substrate that is a support film, the adhesive forms a continuous adhesive layer, resulting in a form in which the substrate is contained within the adhesive layer, which is one form of use of the laminate of the present invention.

[0059] <Adhesive sheet> A laminate of a support film and an adhesive is also called an adhesive sheet. Note that, as mentioned above, even if the adhesive is impregnated into the support film and there is no laminated structure, or if the adhesive can maintain its sheet shape even without a support film, it may still be called an adhesive sheet as long as it is an adhesive sheet. The adhesive sheet of the present invention can be obtained, for example, as follows. A thermosetting adhesive in a solution or dispersion state can be applied to at least one side of a support film and then dried, typically at 40 to 150° C., to obtain a thermosetting adhesive sheet in an uncured state (so-called B-stage state) with a support film attached. The other side of the thermosetting adhesive sheet can then be covered with another support film to obtain the thermosetting adhesive sheet with a support film of the present invention. At least one of the support films used is preferably a peelable support film. That is, a thermosetting adhesive in a solution or dispersion state is applied to a peelable support film and dried to form a thermosetting adhesive sheet, and then the other side of the thermosetting adhesive sheet can be covered with another peelable support film or a non-peelable support film that will serve as the adherend.

[0060] When the adhesive is thermosetting, the adhesive sheet using it is also called a thermosetting adhesive sheet. Furthermore, the layer made of the adhesive is called a thermosetting adhesive layer. Thermosetting refers to hardening at temperatures of about 40 to 200°C.

[0061] This section describes the use of a thermosetting adhesive sheet with a release substrate, in which one side of the thermosetting adhesive sheet is covered with a release substrate and the other side is covered with a sheet-like substrate (e.g., a polyimide film or polyester film). The release substrate is peeled off from the thermosetting adhesive sheet with a release substrate. An adherend (e.g., the circuit side of a printed wiring board having conductive circuits) is placed on top of the exposed thermosetting adhesive layer. Next, the thermosetting adhesive layer sandwiched between the sheet-like substrate and the adherend is thermally cured by applying heat and pressure, and the thermosetting adhesive layer becomes a sheet-like cured product. In this way, the front of a printed wiring board having a conductive circuit can be easily formed through the sheet-like cured product. A printed wiring board with a protective sheet can be obtained, in which the circuit surface is protected by a sheet-like substrate (protective sheet). At least one of the support films used is preferably a peelable support film. That is, a thermosetting adhesive in a solution or dispersion state can be applied to a peelable support film and dried to form a thermosetting adhesive sheet, and then the other side of the thermosetting adhesive sheet can be covered with another peelable support film, or with a non-peelable support film that will serve as the adherend. Alternatively, a thermosetting adhesive in a solution or dispersion state can be applied to a non-peelable support film that will serve as the adherend and dried to form a thermosetting adhesive sheet, and then the other side of the thermosetting adhesive sheet can be covered with another peelable sheet-like substrate.

[0062] The dry film thickness of the thermosetting adhesive sheet is preferably 5 to 500 μm, more preferably 10 to 100 μm, in order to exhibit sufficient adhesiveness and solder heat resistance and from the viewpoint of ease of handling. Examples of application methods include comma coating, knife coating, die coating, lip coating, roll coating, curtain coating, bar coating, gravure printing, flexographic printing, dip coating, spray coating, and spin coating.

[0063] <Insulating layer> The insulating layer used may be a material called heat-resistant class. Examples include cotton, paper, polyethylene, polyvinyl chloride, natural rubber, epoxy resin, melamine resin, phenolic resin, polyimide film, polyester film, polyphenylene ether film, polyphenylene sulfide film, polystyrene film, polycarbonate film, polyether ether ketone film, polyurethane film, mica, asbestos, inorganic materials such as glass fiber, mica, porcelain, etc. Among the support films used, those having releasability include various plastic films that have been subjected to a release treatment, paper that has been subjected to a release treatment, etc. Examples of various plastic films that can be subjected to a release treatment include polyester films and polyolefin films.

[0064] Next, a case where a thermosetting adhesive sheet with a release substrate, in which both sides of a thermosetting adhesive sheet are covered with two release substrates, will be described. One of the release substrates is peeled off from the thermosetting adhesive sheet with the release substrate. An adherend (e.g., a polyimide film or polyester film) is placed on the exposed thermosetting adhesive layer. The other release substrate that was covering the other side of the thermosetting adhesive layer is peeled off. Another adherend (e.g., the circuit side of a printed wiring board having conductive circuits) is placed on the exposed thermosetting adhesive layer. Next, the thermosetting adhesive layer sandwiched between the two adherends is thermally cured by applying heat and pressure. The circuit side of a printed wiring board having conductive circuits is placed on the side from which the release substrate was first peeled, and then a polyimide film or polyester film can be placed on the other side of the thermosetting adhesive layer.

[0065] Examples of printed wiring board laminates (hereinafter also referred to as wiring boards) having conductive circuits include flexible printed wiring boards in which conductive circuits are formed on a flexible, insulating plastic film such as polyester or polyimide. As a method for providing a conductive circuit, for example, a photosensitive etching resist layer can be formed on the copper foil of a flexible copper-clad board, which is made by providing copper foil on a base film with or without an adhesive layer, and then exposing the copper foil through a mask film having a circuit pattern to harden only the exposed areas.The copper foil in the unexposed areas can then be removed by etching, and the remaining resist layer can then be peeled off, thereby forming a conductive circuit from the copper foil. Alternatively, only the necessary circuits may be provided on the base film by means of sputtering, plating, or the like. Alternatively, a conductive ink containing silver or copper particles may be used to form a conductive circuit on a base film by a printing technique.

[0066] <Multi-layer flexible printed wiring> The thermosetting adhesive sheet of the present invention is suitably used for producing a printed wiring board with a protective sheet, and can also be used as follows. The thermosetting adhesive sheet of the present invention can also be sandwiched between a plurality of flexible printed wirings and cured by applying heat and pressure to obtain a multilayer flexible printed wiring board.

[0067] <Laminating base film and copper foil for flexible printed wiring boards> For example, the thermosetting adhesive sheet of the present invention can be sandwiched between a polyimide film and a copper foil, and the sheet can be cured by applying heat and pressure.

[0068] <Conductive adhesive sheet> The thermosetting adhesive sheet of the present invention can be used as a conductive thermosetting adhesive sheet formed by dispersing a thermosetting composition containing a polyimide resin, a curing agent, a specific amount of an alkali metal compound, and a conductive metal filler such as copper or silver, or a conductive filler such as carbon, in the form of a sheet.

[0069] <Electromagnetic wave shield> Furthermore, the thermosetting adhesive sheet of the present invention can be used as an electromagnetic wave shield by forming a multilayer structure with an insulating layer using the conductive thermosetting adhesive sheet prepared above. In addition to the conductive layer, the thermosetting adhesive sheet of the present invention can also be used as an insulating layer.

[0070] <Thermal conductive adhesive sheet> Furthermore, the thermosetting adhesive sheet of the present invention can be used as a thermally conductive thermosetting adhesive sheet formed by dispersing and compounding a polyimide resin, a curing agent, a specific amount of an alkali metal compound, and a thermally conductive inorganic filler, a metal filler, etc., and forming the dispersed thermosetting composition into a sheet. [Example]

[0071] The present invention will be described in more detail below with reference to examples and comparative examples. In the examples and comparative examples, parts and % mean parts by mass and % by mass, respectively, unless otherwise specified.

[0072] The materials used in the examples and their abbreviations are as follows: <Dimer diamine (C)> DA1: Priamine 1075 (manufactured by Croda Japan Co., Ltd.) Amine number 209 DA2: Priamine 1074 (manufactured by Croda Japan) amine value 204 <Other diamines> DA3: 3,3'-dihydroxybenzidine DA4: 1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene DA5: 4,4'-(hexafluoroisopropylidene)bis(2-aminophenol) <Tetracarboxylic acid dianhydride or tetracarboxylic acid (B)> MA1: Hexafluoropropane dianhydride MA2: 3,3',4,4'-biphenyltetracarboxylic dianhydride MA3: 1',2'-dianhydride; 4,4'-[4,4'-(propane-2,2-diyl)diphenoxy]diphthalic dianhydride MA4: Benzene-1,2,4,5-tetracarboxylic acid MA5: 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-C]furan-1,3-dione MA6: 2'-Oxodispiro[bicyclo[2.2.1]heptane-2,1'-cyclopentane-3',2''-bicyclo[2.2.1]heptane]-5,6:5'',6''-tetracarboxylic acid dianhydride MA7: 5-(2,5-dioxotetrahydrofuryl)-3-methyl-3-cyclohexene-1,2-dicarboxylic anhydride <Crosslinking agent> XA1: N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine] XA2: 2,2'-bis[4-(4-maleimidophenoxy)phenyl]propane <Curing accelerator> CA1: Dicumyl peroxide

[0073] (Example 1) Production of polyimide resin (PI-1) A reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet tube was charged with 1186 parts of N,N-dimethylformamide and 590 parts of hexafluoropropane dianhydride, and the mixture was heated to 100°C while stirring under a nitrogen stream. 596 parts of 1075 methyl methyl amine was added dropwise over 1 hour, followed by 37 parts of 2-aminoethanethiol. The mixture was heated to 140°C and dehydration reaction was carried out for 14 hours. The mixture was then heated to 200°C while removing the solvent, and 1175 parts of toluene was added to adjust the solids concentration to 50%. A resin solution of sulfanyl-terminated polyimide resin (PI-1) with Mn of 8,239 and Mw of 16,915 was obtained.

[0074] (Examples 2 to 17) Production of polyimide resins (PI-2 to PI-17) Polyimide resins (PI-2 to PI-17) having sulfanyl groups at their termini were obtained in the same manner as in Example 1, except that the types and amounts of materials were changed according to Table 1. In Table 1, unless otherwise specified, the numbers represent parts, and blank spaces indicate that no ingredients were added.

[0075] (Comparative Example 1) Production of Polyimide (A-1) A reaction vessel equipped with a stirrer, thermometer, reflux condenser, dropping tank, and nitrogen gas inlet tube was charged with 1186 parts of N,N-dimethylformamide and 399 parts of 1,3,3a,4,5,9b-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)naphtho[1,2-C]furan-1,3-dione, and the mixture was heated to 100°C while stirring under a nitrogen stream. After 699 parts of 1074 propylamine were added dropwise over 1 hour, the mixture was heated to 140°C and dehydration reaction was carried out for 14 hours. The mixture was then heated to 200°C while removing the solvent, and 1045 parts of toluene was added to adjust the solids concentration to 50%. A resin solution of polyimide (A-1) with Mn 20,891 and Mw 48,049 was obtained.

[0076] The Mn, Mw, acid value and Tg of the obtained polyimide resins (PI-1 to PI-17) and polyimide (A-1) were measured by the following methods. The results are shown in Table 1.

[0077] <Measurement of number average molecular weight (Mn) and mass average molecular weight (Mw)> Measurements of Mn and Mw were performed using a GPC (gel permeation chromatography) "HPC-8020" manufactured by Tosoh Corporation. GPC is a liquid chromatography that separates and quantifies substances dissolved in a solvent (THF; tetrahydrofuran) based on differences in their molecular size. Measurements in the present invention were performed using two "LF-604" columns (Showa Denko K.K.: GPC columns for rapid analysis: 6 mm ID x 150 mm size) connected in series, at a flow rate of 0.6 ml / min and a column temperature of 40°C. Mn and Mw are values converted into polystyrene equivalents.

[0078] <Measurement of glass transition temperature (Tg)> Using a blade coater, the resin solution was uniformly coated onto a release-treated polyester film so that the film thickness after drying would be 50 μm, and the film was pre-dried at 100°C for 20 minutes. After drying, the polyester film was peeled off to obtain a solid resin. Using a "Differential Scanning Calorimeter DSC-60 PLUS" manufactured by Shimadzu Corporation, 10 mg of the solid resin obtained above was used under the conditions of a starting temperature of 25°C, an ending temperature of 250°C, and a heating rate of 10.0°C / min. After the first heating cycle, the resin was rapidly cooled to the starting temperature, and the peak value measured in the second cycle under the same conditions was taken as Tg.

[0079] <Method for measuring acid value> Approximately 1 g of resin solution was precisely weighed and placed in a stoppered Erlenmeyer flask, and 100 ml of a toluene / ethanol (volume ratio: toluene / ethanol = 2 / 1) mixture was added to dissolve it. Phenolphthalein test solution was added as an indicator and the mixture was left to stand for 30 seconds. After that, the solution was titrated with 0.1 N alcoholic potassium hydroxide solution until it turned pale pink, and the acid value was calculated using the following formula. (Formula 1) Acid value (mgKOH / g)=(5.611×a×F) / (S×b) S: Amount of sample collected (g) a: Consumption of 0.1N alcoholic potassium hydroxide solution (ml) b: Solid content of sample (%) F: Factor of 0.1N alcoholic potassium hydroxide solution

[0080] <200℃ heat resistance> The obtained resin solutions of Examples 1 to 17 and Comparative Example 1 were uniformly coated onto a release-treated polyester film using a blade coater so that the film thickness after drying would be 50 μm, and the film was pre-dried at 100°C for 20 minutes. After drying, the polyester film was peeled off to obtain a resin sheet. The obtained sheet was aged in an oven at 200°C for 2 hours. The aged sheet was dissolved in THF, and the mass average molecular weight was measured by GPC, and the molecular weight change rate was calculated using the following formula. (Equation 2) Molecular weight change rate (%) = (molecular weight before aging - molecular weight after aging) / molecular weight before aging This test was conducted to evaluate the heat resistance of the resin when used under heating, and the results were judged according to the following criteria. ◎: Molecular weight change rate less than 5% (very good) ○: Molecular weight change rate 5% or more but less than 10% (good) △: Molecular weight change rate 10% or more but less than 30% (usable) ×: Molecular weight change rate 30% or more (unusable)

[0081] <260℃ heat resistance> A resin sheet was prepared in the same manner as in the 200°C heat resistance test, and the obtained sheet was aged for 2 hours in an oven at 260°C. The aged sheet was dissolved in THF, and the weight average molecular weight was measured by GPC, and the molecular weight change rate was calculated using the above formula (2). This test was conducted to evaluate the heat resistance of the resin when used under heating, and the results were judged according to the following criteria. ◎: Molecular weight change rate less than 5% (very good) ○: Molecular weight change rate 5% or more but less than 10% (good) △: Molecular weight change rate 10% or more but less than 30% (usable) ×: Molecular weight change rate 30% or more (unusable)

[0082] <20℃ 60%RH humidity resistance> A resin sheet was prepared in the same manner as in the 200°C heat resistance test, and the obtained sheet was aged for 2 weeks under conditions of 20°C and 60% relative humidity (hereinafter referred to as 60% RH). The aged sheet was dissolved in THF to measure the acid value, and the rate of change in acid value was calculated using the following formula. (Equation 3) Acid value change rate (%) = (acid value after aging - acid value before aging) / acid value before aging This test was conducted to evaluate the heat resistance of the resin when used under heating, and the results were judged according to the following criteria. ○: Acid value change rate less than 5% (good) △: Acid value change rate 5% or more but less than 50% (usable) ×: Acid value change rate 50% or more (unusable)

[0083] [Example 18] 30 parts of polymer (PI-1) solution (solid content concentration 50%) and 0.6 parts of N,N'-[1,3-phenylenebis(methylene)]bis[bis(oxiran-2-ylmethyl)amine] as a crosslinker were placed in a mayonnaise bottle and mixed at room temperature for 30 minutes using a mix rotor to obtain the adhesive of Example 18.

[0084] [Examples 19 to 38, Comparative Examples 2 and 3] The adhesives of Examples 19 to 38 and Comparative Examples 2 and 3 were obtained in the same manner as in Example 18, except that the materials and blending amounts were changed as shown in Table 2.

[0085] (Preparation of adhesive sheet with polyimide film substrate) Each of the adhesives of Examples 18 to 38 and Comparative Examples 2 and 3 was applied using a blade coater onto a 75 μm thick polyimide film ("Kapton (registered trademark) 300H" manufactured by DuPont-Toray Co., Ltd.) so that the thickness after drying would be 30 μm. A release-treated polyester film was placed on top of the adhesive surface, and the film was heated in a vacuum press molding machine at 80°C for 1 minute to obtain an adhesive sheet with a polyimide film substrate.

[0086] [Example 39] Preparation of laminate The adhesive surface of an adhesive sheet with a polyimide film substrate having an adhesive layer made of the adhesive of Example 18 was overlapped with the surface-roughened side of an electrolytic copper foil (F2-WS), and then the two were laminated at 80°C, followed by pressure bonding for 2 hours in a vacuum press at 200°C and 1.0 MPa to produce the laminate of Example 39.

[0087] [Examples 40 to 59, Comparative Examples 4 to 5] Laminates of Examples 40 to 59 and Comparative Examples 4 to 5 were prepared in the same manner as in Example 39, except that the adhesive sheet with a polyimide film substrate was changed to one having an adhesive layer made of the adhesive of Examples 19 to 38 and Comparative Examples 2 to 3.

[0088] (Preparation of test specimens) Test pieces measuring 10 mm in width and 65 mm in length were cut out from the laminate prepared above, and the adhesive properties, heat-resistant adhesive properties, and dielectric properties (dielectric constant and dielectric loss tangent) were evaluated using the test pieces obtained.

[0089] <Adhesiveness> The test pieces were subjected to a T-peel test at a pulling speed of 300 mm / min in an atmosphere of 23°C and 50% relative humidity to measure the adhesive strength (N / cm). This test evaluates the adhesive strength of the adhesive layer when used at room temperature, and the results were judged according to the following criteria. ◎: Adhesive strength 8.0N / 3mm or more (very good) ○: Adhesive strength 6.0N / 3mm or more but less than 8.0N / 3mm (good) △: Adhesive strength 4.0N / 3mm or more but less than 6.0N / 3mm (usable) ×: Adhesive strength less than 4.0N / 3mm (unusable)

[0090] <Heat-resistant adhesiveness> The test piece was stored in an air atmosphere at 150°C for 1000 hours, and after being taken out, the adhesive strength was measured in the same manner as above, and the adhesive strength reduction rate was calculated using the following formula. (Equation 4) Adhesion strength decrease rate (%) = (adhesion strength before aging - adhesion strength after aging) / adhesion strength before aging The rate of decrease in adhesive strength relative to the adhesive strength measured in the above <Adhesion> was judged according to the following criteria. ◎ Reduction rate is less than 20% (very good) ○ Reduction rate is between 20% and 50% (good) △... Reduction rate is between 50% and 80% (usable) ×...Drop rate is 80% or more (cannot be used)

[0091] <Dielectric properties> (dielectric constant) Three test pieces were set in the relative permittivity measuring device "ADMS01Oc" manufactured by AET Corporation, and the relative permittivity was determined using the cavity resonator method at a measurement temperature of 23°C and a measurement frequency of 10 GHz, and evaluated according to the following criteria. ◎: Dielectric constant less than 2.5 (very good) ○: Dielectric constant 2.5 or more and less than 2.6 (good) △: Dielectric constant 2.6 or more and less than 2.7 (usable) ×: Dielectric constant 2.7 or more (unusable)

[0092] (dielectric tangent) Three test pieces were set in the relative permittivity measuring device "ADMS01Oc" manufactured by AET Corporation, and the dielectric loss tangent was determined using the cavity resonator method at a measurement temperature of 23°C and a measurement frequency of 10 GHz, and evaluated according to the following criteria. ◎: Dielectric tangent less than 0.002 (very good) ○: Dielectric loss tangent 0.002 or more and less than 0.003 (good) △: Dielectric loss tangent 0.003 or more and less than 0.005 (usable) ×: Dielectric tangent 0.005 or more (unusable)

[0093] [Table 1]

[0094] [Table 2]

[0095] As shown in Table 1, the polyimide resins of the present invention having sulfanyl groups at their termini are superior in heat resistance at 200°C and 260°C and moisture resistance at 20°C / 60% RH compared to Comparative Example 1, in which the termini are acid anhydrides. In particular, Examples 3, 4, 6 to 14, and 16, which contain tetracarboxylic dianhydrides having an alicyclic structure, are superior in heat resistance at 200°C, and among these, Examples 9 and 13, which contain aromatic diamines (excluding diamines having a phenol skeleton), and Examples 8, 10, 12, and 14, which contain diamines having a phenol group, are also superior in heat resistance at 260°C. Furthermore, the adhesive obtained from the thermosetting composition of the present invention has excellent dielectric properties such as relative permittivity and dielectric loss tangent compared to Comparative Examples 2 and 3, and also has high adhesiveness and heat-resistant adhesiveness. In particular, Examples 20, 21, 23-31, and 33-37, which contain polyimide resins having terminal sulfanyl groups and containing tetracarboxylic dianhydrides with alicyclic structures, have excellent heat-resistant adhesiveness, and among them, Examples 26 and 30, which contain aromatic diamines (excluding diamines having a phenol skeleton), and Examples 25, 27, 29, 31, and 36, which contain polyimide resins having terminal sulfanyl groups and diamines with phenol groups, have particularly excellent heat-resistant adhesiveness. Among these, Example 36, which used maleimide as a crosslinker and peroxide as a curing accelerator, showed particularly excellent dielectric properties.

[0096] (Printed wiring board manufacturing) The adhesive of Example 18 was applied to Kapton® H-type substrate using a blade coater to a dried thickness of 30 μm, and then dried at 100°C for 3 minutes to obtain an adhesive sheet. The treated side of the electrolytic copper foil (F2-WS) was then placed on the adhesive surface of the adhesive sheet, and the resulting foil was pressed with a laminating roll at 100°C. This was then processed in a vacuum press molding machine at 150°C for 30 minutes to obtain a laminate. The copper surface of this laminate was soft-etched to form a copper circuit, and the adhesive resin side of the adhesive sheet with substrate obtained by the above method was then placed on top of the copper circuit. This was then heat-pressed in a vacuum press molding machine at a pressure of 10 MPa, 180°C, and 1 minute, followed by further heating at 200°C for 2 hours, thereby producing a flexible printed wiring board. It was also confirmed that flexible printed wiring boards could be produced in the same manner using the adhesive compositions of other Examples.

Claims

1. The present invention relates to a polyimide resin having a sulfanyl group at a terminal thereof, which is a reaction product of a polyimide (A) containing a residue derived from a tetracarboxylic dianhydride or tetracarboxylic acid (B) and a dimer diamine (C) with a terminal modifier (D) having a sulfanyl group, and a crosslinking agent, An adhesive in which the crosslinking agent comprises a bismaleimide resin.

2. 2. The adhesive according to claim 1, wherein the tetracarboxylic dianhydride or the tetracarboxylic acid (B) has an alicyclic structure.

3. The adhesive according to claim 1 or 2, wherein the polyimide (A) further contains an aromatic diamine (excluding a diamine having a phenol skeleton) and / or a residue derived from a diamine having a phenol skeleton.

4. An adhesive described in any one of claims 1 to 3, further containing a curing accelerator.

5. A laminate comprising an adhesive layer made of the adhesive according to claim 4 and a substrate.

6. 6. The laminate according to claim 5, wherein the substrate comprises a copper foil and / or an insulating layer.

7. 7. The laminate according to claim 5, which is for use in a printed wiring board.

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