Polyolefin-based adhesive composition

Abstract

The present invention addresses the problem of providing an adhesive composition which has high adhesion between a metal substrate and a non-polar resin substrate such as one made of a liquid crystal polymer, also has solder heat resistance and low dielectric properties, and moreover has an exceptional dielectric tangent after water-absorption saturation.　This adhesive composition contains an acid-modified polyolefin (a) and an epoxy resin (b), and satisfies conditions (1) and (2). (1) The relative dielectric constant (εc1) at 1 GHz immediately after curing of a cured product of the adhesive composition is 3.0 or less, and the dielectric tangent (tanδ1) is 0.02 or less. (2) The amount of change between the dielectric tangent (tanδ1) at 1 GHz immediately after curing of a cured product of the adhesive composition and the dielectric tangent (tanδ2) at 1 GHz after the cured product has been immersed in 25°C water for 24 hours is 0.01 or less.

Description

Technical Field

[0001] The present invention relates to a polyolefin-based adhesive composition. More specifically, it relates to a polyolefin-based adhesive composition used for bonding a resin substrate to another resin substrate or a metal substrate. In particular, it relates to an adhesive composition for a flexible printed wiring board (hereinafter abbreviated as FPC), and a cover film, a laminate, a copper foil with resin, and a bonding sheet containing the same.

Background Art

[0002] A flexible printed wiring board (FPC) has excellent flexibility, so it can cope with the multifunctionalization and miniaturization of personal computers (PCs), smartphones, etc. Therefore, it is widely used for incorporating an electronic circuit board into a narrow and complex interior. In recent years, the miniaturization, weight reduction, 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 due to these trends. In particular, with the speeding up of transmission signals in FPCs, the frequency of signals has been increasing. Along with this, the requirement for low dielectric characteristics (low relative dielectric constant, low dielectric tangent) in the high-frequency region for FPCs has been increasing. In order to achieve such low dielectric characteristics, measures have been taken to reduce the dielectric loss of the base material and adhesive of FPCs. As adhesives, combinations of polyimide using dimer diamine and epoxy resin have been developed (Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Disclosure of the Invention

Problems to be Solved by the Invention

[0004] However, terminals such as smartphones are used in a humid environment. With adhesives using polyimide as in Patent Document 1, it has been found that polyimide absorbs moisture over time, and as a result, the dielectric tangent in the moisture-absorbed state deteriorates. Therefore, as in Patent Document 1, when the resin has high hygroscopicity, it has been found that the adhesiveness, solder heat resistance, dielectric properties (relative permittivity, dielectric tangent) of the adhesive containing the resin, and the dielectric tangent after moisture absorption (hereinafter also referred to as saturated water absorption) are insufficient.

[0005] As a result of intensive studies to solve the above problems, the present invention has found that an adhesive composition containing an acid-modified polyolefin (a) and an epoxy resin (b) exhibits excellent adhesiveness, solder heat resistance, and low dielectric properties (relative permittivity, dielectric tangent) between a resin base material and a metal base material, and further has an excellent dielectric tangent after moisture absorption (saturated water absorption), thus completing the present invention.

[0006] That is, an object of the present invention is to provide an adhesive composition having good adhesiveness to both various resin base materials such as polyimide (PI) and liquid crystal polymer (LCP) and metal base materials, and also excellent in solder heat resistance, dielectric properties, and dielectric tangent after moisture absorption (saturated water absorption).

Means for Solving the Problems

[0007] An adhesive composition containing an acid-modified polyolefin (a) and an epoxy resin (b), which satisfies the following (1) to (2). (1) The relative permittivity (ε c 1) at 1 GHz immediately after curing of the cured product of the adhesive composition is 3.0 or less, and the dielectric tangent (tanδ1) is 0.02 or less. (2) The change amount of the dielectric tangent (tanδ1) at 1 GHz immediately after curing of the cured product of the adhesive composition and the dielectric tangent (tanδ2) at 1 GHz after immersion in water at 25 °C for 24 hours is 0.01 or less.

[0008] The acid value of the acid-modified polyolefin (a) is preferably 5 to 40 mgKOH / g. It is preferable to contain 1 to 40 parts by mass of the epoxy resin (b) with respect to 100 parts by mass of the acid-modified polyolefin (a), and it is further preferable to contain an oligophenylene ether (c) and / or a carbodiimide compound (d).

[0009] An adhesive sheet or laminate having a layer containing the above adhesive composition. A printed wiring board including the laminate as a component.

Advantages of the Invention

[0010] The adhesive composition according to the present invention has good adhesiveness to both various resin substrates such as polyimide and liquid crystal polymer and metal substrates, and has good solder heat resistance, low dielectric characteristics, and little change in dielectric tangent after moisture absorption (saturated water absorption), and is stable.

Embodiments for Carrying Out the Invention

[0011] <Acid-modified polyolefin (a)> The acid-modified polyolefin (a) (hereinafter, also simply referred to as component (a)) used in the present invention is not limited, but is preferably obtained by grafting at least one of α,β-unsaturated carboxylic acids and their acid anhydrides onto a polyolefin resin. The polyolefin resin refers to a homopolymer of an olefin monomer exemplified by ethylene, propylene, butene, butadiene, isoprene, etc., or a copolymer with other monomers, and polymers mainly composed of a hydrocarbon skeleton such as hydrides and halides of the obtained polymers. That is, the acid-modified polyolefin is preferably obtained by grafting at least one of α,β-unsaturated carboxylic acids and their acid anhydrides onto at least one of polyethylene, polypropylene, and propylene-α-olefin copolymers.

[0012] A propylene-α-olefin copolymer is obtained by copolymerizing propylene as the main component with an α-olefin. As the α-olefin, for example, ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate, etc. can be used alone or in combination of several kinds. Among these α-olefins, ethylene and 1-butene are preferred. The ratio of the propylene component to the α-olefin component in the propylene-α-olefin copolymer is not limited, but the propylene component is preferably 50 mol% or more, more preferably 70 mol% or more.

[0013] Examples of at least one of the α,β-unsaturated carboxylic acid and its acid anhydride include maleic acid, itaconic acid, citraconic acid, and their acid anhydrides. Among these, acid anhydrides are preferred, and maleic anhydride is more preferred. Specifically, maleic anhydride-modified polypropylene, maleic anhydride-modified propylene-ethylene copolymer, maleic anhydride-modified propylene-butene copolymer, maleic anhydride-modified propylene-ethylene-butene copolymer, etc. can be mentioned, and these acid-modified polyolefins can be used alone or in combination of two or more kinds.

[0014] From the viewpoints of heat resistance and adhesiveness to resin substrates and metal substrates, the acid value of the acid-modified polyolefin (a) is preferably 5 mgKOH / g or more, more preferably 6 mgKOH / g or more, and even more preferably 7 mgKOH / g or more. By setting it above the lower limit value, the compatibility with the epoxy resin (b) becomes good, and excellent adhesive strength can be exhibited. Also, the crosslinking density is high and the heat resistance is good. Furthermore, the dielectric loss tangent hardly increases after moisture absorption (saturated water absorption). The upper limit is preferably 40 mgKOH / g or less, more preferably 35 mgKOH / g or less, and even more preferably 30 mgKOH / g or less. By setting it below the upper limit value, the adhesiveness and the dielectric loss tangent after saturated water absorption become good.

[0015] The number average molecular weight (Mn) of the acid-modified polyolefin (a) is preferably in the range of 10,000 to 50,000. More preferably, it is in the range of 15,000 to 45,000, still more preferably in the range of 20,000 to 40,000, and particularly preferably in the range of 22,000 to 38,000. By setting it to be not less than the lower limit value, the cohesive force becomes good and excellent adhesiveness can be exhibited. Further, by setting it to be not more than the upper limit value, the fluidity is excellent and the operability becomes good.

[0016] The acid-modified polyolefin (a) is preferably a crystalline acid-modified polyolefin. The crystallinity referred to in the present invention means that, using a differential scanning calorimeter (DSC), the temperature is raised from -100°C to 250°C at a rate of 20°C / min, and the one showing a clear melting peak in the temperature raising process is meant.

[0017] The melting point (Tm) of the acid-modified polyolefin (a) is preferably in the range of 50°C to 120°C. More preferably, it is in the range of 60°C to 100°C, and most preferably in the range of 70°C to 90°C. By setting it to be not less than the lower limit value, the cohesive force derived from crystals becomes good and excellent adhesiveness and heat resistance can be exhibited. Further, by setting it to be not more than the upper limit value, the solution stability and fluidity are excellent and the operability at the time of adhesion becomes good.

[0018] The heat of fusion (ΔH) of the acid-modified polyolefin (a) is preferably in the range of 5 J / g to 60 J / g. More preferably, it is in the range of 10 J / g to 50 J / g, and most preferably in the range of 20 J / g to 40 J / g. By setting it to be not less than the lower limit value, the cohesive force derived from crystals becomes good and excellent adhesiveness and heat resistance can be exhibited. Further, by setting it to be not more than the upper limit value, the solution stability and fluidity are excellent and the operability at the time of adhesion becomes good.

[0019] The production method of the acid-modified polyolefin (a) is not particularly limited, and examples thereof include a radical graft reaction (that is, a reaction in which radical species are generated for the polymer serving as the main chain, and unsaturated carboxylic acids and acid anhydrides are graft-polymerized using the radical species as a polymerization initiation point), and the like.

[0020] Although the radical generator is not particularly limited, it is preferable to use an organic peroxide. The organic peroxide is not particularly limited, and examples thereof include peroxides such as di-tert-butyl peroxyphthalate, tert-butyl hydroperoxide, dicumyl peroxide, benzoyl peroxide, tert-butyl peroxybenzoate, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxypivalate, methyl ethyl ketone peroxide, di-tert-butyl peroxide, lauroyl peroxide; azonitriles such as azobisisobutyronitrile and azobisisopropionitrile.

[0021] <Epoxy resin (b)> The epoxy resin (b) used in the present invention (hereinafter, also simply referred to as component (b)) is not particularly limited as long as it has an epoxy group in the molecule, but preferably has two or more glycidyl groups in the molecule. Specifically, although not particularly limited, at least one selected from the group consisting of biphenyl type epoxy resin, naphthalene type epoxy resin, bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak type epoxy resin, alicyclic epoxy resin, dicyclopentadiene type epoxy resin, tetraglycidyldiaminodiphenylmethane, triglycidyl para-aminophenol, tetraglycidyl bisaminomethylcyclohexanone, N,N,N’,N’-tetraglycidyl-m-xylenediamine, and epoxy-modified polybutadiene can be used. Preferably, it is a biphenyl type epoxy resin, a novolak type epoxy resin, a dicyclopentadiene type epoxy resin or an epoxy-modified polybutadiene. More preferably, it is a dicyclopentadiene type epoxy resin.

[0022] The epoxy equivalent of the epoxy resin (b) is preferably 50 g / eq or more, more preferably 100 g / eq or more, still more preferably 150 g / eq or more. Also, it is preferably 400 g / eq or less, more preferably 350 g / eq or less, still more preferably 300 g / eq or less. By setting it within the above range, excellent solder heat resistance can be exhibited.

[0023] In the adhesive composition of the present invention, the content of the epoxy resin (b) is preferably 0.5 part by mass or more, more preferably 1 part by mass or more, still more preferably 5 parts by mass or more, and particularly preferably 10 parts by mass or more with respect to 100 parts by mass of the acid-modified polyolefin (a). By setting it to the above lower limit value or more, a sufficient curing effect can be obtained, and excellent adhesiveness and solder heat resistance can be exhibited. Also, it is preferably 60 parts by mass or less, more preferably 50 parts by mass or less, still more preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less. By setting it to the above upper limit value or less, the dielectric properties of the adhesive composition become good. That is, by setting it within the above range, an adhesive composition excellent in adhesiveness, solder heat resistance, low dielectric properties, and dielectric tangent after saturated water absorption can be obtained.

[0024] <Adhesive composition> The adhesive composition of the present invention is a composition containing at least the acid-modified polyolefin (a) and the epoxy resin (b), and preferably further contains an oligophenylene ether (c) and / or a carbodiimide compound (d). The adhesive composition of the present invention has excellent adhesiveness to low-polarity resin substrates such as liquid crystal polymers and metal substrates as well as polyimide, and further has excellent solder heat resistance, electrical properties (low dielectric properties), and dielectric tangent after moisture absorption (saturated water absorption). That is, when the adhesive composition is applied to a substrate, the cured adhesive coating film (adhesive layer) can exhibit excellent electrical properties.

[0025] The adhesive composition according to the present application has a relative permittivity (ε at a frequency of 1 GHz immediately after curing c1) is 3.0 or less. Preferably it is 2.6 or less, more preferably 2.3 or less. The lower limit is not particularly limited, but in practice it is 2.0. Also, the relative permittivity (ε c 1) is preferably 3.0 or less, more preferably 2.6 or less, and even more preferably 2.3 or less.

[0026] For the adhesive composition according to the present invention, the dielectric loss tangent (tanδ1) at a frequency of 1 GHz immediately after curing is 0.02 or less. Preferably it is 0.01 or less, more preferably 0.008 or less. The lower limit is not particularly limited, but in practice it is 0.0001. Also, the dielectric loss tangent (tanδ1) in the entire frequency range of 1 GHz to 60 GHz is preferably 0.02 or less, more preferably 0.01 or less, and even more preferably 0.008 or less.

[0027] In the present invention, the relative permittivity (ε c ) and the dielectric loss tangent (tanδ) can be measured as follows. That is, the adhesive composition is applied to a release substrate so that the thickness after drying is 25 μm, and dried at about 130 °C for about 3 minutes. Then, it is heat-treated at about 140 °C for about 4 hours to be cured, and the cured adhesive composition layer (adhesive layer) is peeled off from the release film. The relative permittivity (ε c 1) at a frequency of 1 GHz of the adhesive composition layer after peeling is measured. Specifically, the relative permittivity (ε c 1) and the dielectric loss tangent (tanδ1) can be calculated from the measurement by the cavity resonator perturbation method. Here, immediately after curing means within 30 minutes after heat treatment curing.

[0028] Even after the cured product of the adhesive composition according to the present invention is allowed to absorb moisture (saturated water absorption), almost no increase in the dielectric loss tangent is observed. Specifically, the change amount between the dielectric loss tangent (tanδ1) at 1 GHz immediately after curing and the dielectric loss tangent (tanδ2) at 1 GHz of the cured product after being immersed in water at 25°C for 24 hours after curing is 0.01 or less. Preferably, it is 0.008 or less, more preferably 0.005 or less. The lower limit may be 0.0001 or more industrially, and may be 0.001 or more. The change amount is the difference between (tanδ1) and (tanδ2), and can be obtained by change amount = |(tanδ1) - (tanδ2)|.

[0029] It is preferable that the adhesive composition according to the present invention shows almost no increase in the relative permittivity even after the cured product of the adhesive composition is allowed to absorb moisture (saturated water absorption). Specifically, the relative permittivity (ε c 2) at a frequency of 1 GHz after the cured product of the adhesive composition is allowed to absorb moisture (saturated water absorption) is preferably 3.0 or less. More preferably, it is 2.6 or less, and still more preferably 2.3 or less. The lower limit is not particularly limited, but is 2.0 in practical use. Also, the relative permittivity (ε c 2) in the entire region from a frequency of 1 GHz to 60 GHz is preferably 3.0 or less, more preferably 2.6 or less, and still more preferably 2.3 or less.

[0030] The total amount of maleic acid and maleic anhydride contained in the adhesive composition is preferably 1% by mass or less. Since the adhesiveness, solder heat resistance, and pot life are good, it is more preferably 0.8% by mass or less, still more preferably 0.6% by mass or less, and particularly preferably 0.4% by mass or less. Although the total of maleic anhydride and maleic acid is preferably as small as possible, it may be 0.01% by mass or more industrially, and may be 0.1% by mass or more.

[0031] <Oligophenylene ether (c)> By incorporating oligo(phenylene ether) (c) into the adhesive composition of the present invention, even better solder heat resistance can be exhibited. Further, by incorporating oligo(phenylene ether) (c), an increase in the dielectric tangent after moisture absorption can be suppressed. The oligo(phenylene ether) (c) (hereinafter, also simply referred to as component (c)) used in the present invention is not particularly limited, but is preferably a compound having a structural unit represented by the following general formula (c1) and / or a structural unit of general formula (c2).

Chemical formula

[0032] In general formula (c1), R1, R2, R3, and R4 are each independently preferably a hydrogen atom, an optionally substituted alkyl group, an optionally substituted alkenyl group, an optionally substituted alkynyl group, an optionally substituted aryl group, an optionally substituted aralkyl group, or an optionally substituted alkoxy group. The "alkyl group" of the optionally substituted alkyl group is, for example, a linear or branched alkyl group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. More specifically, examples include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, a hexyl group, etc., and a methyl group or an ethyl group is more preferable. Examples of the "alkenyl group" of the optionally substituted alkenyl group include an ethenyl group, a 1-propenyl group, a 2-propenyl group, a 3-butenyl group, a pentenyl group, a hexenyl group, etc., and an ethenyl group or a 1-propenyl group is more preferable. Examples of the "alkynyl group" of the optionally substituted alkynyl group include an ethynyl group, a 1-propynyl group, a 2-propynyl (propargyl) group, a 3-butynyl group, a pentynyl group, a hexynyl group, etc., and an ethynyl group, a 1-propynyl group, or a 2-propynyl (propargyl) group is more preferable. Examples of the "aryl group" of the optionally substituted aryl group include a phenyl group, a naphthyl group, etc., and a phenyl group is more preferable. Examples of the "aralkyl group" of the optionally substituted aralkyl group include a benzyl group, a phenethyl group, a 2-methylbenzyl group, a 4-methylbenzyl group, an α-methylbenzyl group, a 2-vinylphenethyl group, a 4-vinylphenethyl group, etc., and a benzyl group is more preferable. The "alkoxy group" of the optionally substituted alkoxy group is, for example, a linear or branched alkoxy group having 1 to 6 carbon atoms, preferably 1 to 3 carbon atoms. For example, a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a tert-butoxy group, a pentyloxy group, a hexyloxy group, etc. are included, and a methoxy group or an ethoxy group is more preferable.When the above alkyl group, aryl group, alkenyl group, alkynyl group, aralkyl group, and alkoxy group are substituted, they may have one or more substituents. Such substituents include, for example, halogen atoms (e.g., fluorine atom, chlorine atom, bromine atom), alkyl groups having 1 to 6 carbon atoms (e.g., methyl group, ethyl group, propyl group, isopropyl group, butyl group, isobutyl group, sec-butyl group, tert-butyl group, pentyl group, hexyl group), aryl groups (e.g., phenyl group, naphthyl group), alkenyl groups (e.g., ethenyl group, 1-propenyl group, 2-propenyl group), alkynyl groups (e.g., ethynyl group, 1-propynyl group, 2-propynyl group), aralkyl groups (e.g., benzyl group, phenethyl group), alkoxy groups (e.g., methoxy group, ethoxy group), and the like. Among them, it is preferable that R1 and R4 are methyl groups and R2 and R3 are hydrogen.

[0033]

Chemical formula

[0034] Oligophenylene ether (c) may be partially or entirely a modified polyphenylene ether functionalized with an ethylenically unsaturated group such as a vinylbenzyl group, an epoxy group, an amino group, a hydroxy group, a mercapto group, a carboxyl group, and a silyl group, etc. Further, it is preferable that both ends have a hydroxy group, an epoxy group, or an ethylenically unsaturated group. Examples of the ethylenically unsaturated group include alkenyl groups such as an ethenyl group, an allyl group, a methacryl group, a propenyl group, a butenyl group, a hexenyl group, an octenyl group, etc., cycloalkenyl groups such as a cyclopentenyl group, a cyclohexenyl group, etc., and alkenylaryl groups such as a vinylbenzyl group, a vinylnaphthyl group, etc. Also, both ends may be the same functional group or different functional groups. From the viewpoint of highly controlling the balance between low dielectric tangent and reduction of resin residue, it is preferable that both ends are a hydroxy group or a vinylbenzyl group, and it is more preferable that both ends are a hydroxy group or a vinylbenzyl group.

[0035] As the compound having a structural unit represented by the general formula (c1), a compound of the general formula (c3) is particularly preferable.

Chemical formula

[0036] In addition, as the compound having a structural unit represented by the general formula (c2), a compound of the general formula (c4) is particularly preferable. [Chemical formula] In the general formula (c4), n is preferably 2 or more, more preferably 4 or more, preferably 23 or less, more preferably 20 or less, and even more preferably 18 or less.

[0037] The number average molecular weight of the oligo(phenylene ether) (c) is preferably 3000 or less, more preferably 2700 or less, and even more preferably 2500 or less. Also, the number average molecular weight of the oligo(phenylene ether) (c) is preferably 500 or more, more preferably 700 or more. By setting the number average molecular weight of the oligo(phenylene ether) (c) to be at least the lower limit value, the flexibility of the obtained adhesive layer can be improved. On the other hand, by setting the number average molecular weight of the oligo(phenylene ether) (c) to be at most the upper limit value, the solubility in an organic solvent can be improved.

[0038] When the oligo(phenylene ether) (c) is contained, its content is preferably 0.05 parts by mass or more with respect to 100 parts by mass of the acid-modified polyolefin (a). Since excellent solder heat resistance can be exhibited, it is more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more. Also, it is preferably 200 parts by mass or less. Since excellent adhesiveness and solder heat resistance can be exhibited, it is more preferably 150 parts by mass or less, even more preferably 100 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0039] <Carbodiimide compound (d)> The carbodiimide compound (d) used in the present invention (hereinafter, also simply referred to as the component (d)) is preferably a polyfunctional carbodiimide compound having two or more carbodiimide groups in one molecule. By using the carbodiimide compound (d), the carboxylic anhydride group of the acid-modified polyolefin reacts with the carbodiimide, enhancing the interaction between the adhesive composition and the substrate, and improving the adhesiveness and solder heat resistance.

[0040] When the carbodiimide compound (d) is contained, its content is preferably 0.5 part by mass or more with respect to 100 parts by mass of the acid-modified polyolefin (a). Since a sufficient curing effect can be obtained and excellent adhesiveness and solder heat resistance can be exhibited, it is more preferably 1 part by mass or more, still more preferably 1.5 parts by mass or more, and particularly preferably 2 parts by mass or more. Further, in addition to adhesiveness and solder heat resistance, since it has excellent low dielectric properties, it is preferably 20 parts by mass or less, more preferably 15 parts by mass or less, still more preferably 10 parts by mass or less, and particularly preferably 5 parts by mass or less.

[0041] The carbodiimide compound (d) may be any of an aromatic carbodiimide compound, an alicyclic carbodiimide compound, or an aliphatic carbodiimide compound, and these can be used alone or in combination of two or more. Examples of the aromatic carbodiimide compound include poly-m-phenylene carbodiimide, poly-p-phenylene carbodiimide, polytolylene carbodiimide, poly(diisopropylphenylene carbodiimide), poly(methyldiisopropylphenylene carbodiimide), poly(4,4'-diphenylmethane carbodiimide), and the like. Examples of the alicyclic carbodiimide compound include poly-m-cyclohexyl carbodiimide, poly-p-cyclohexyl carbodiimide, poly(4,4'-dicyclohexylmethane carbodiimide), poly(3,3'-dicyclohexylmethane carbodiimide), and the like. The aliphatic carbodiimide compound may be either a linear or branched aliphatic carbodiimide compound. A linear aliphatic carbodiimide compound is preferred, and specifically, polymethylene carbodiimide, polyethylene carbodiimide, polypropylene carbodiimide, polybutylene carbodiimide, polypentamethylene carbodiimide, polyhexamethylene carbodiimide, and the like can be mentioned. These can be used alone or in combination of two or more. Among them, an aromatic carbodiimide compound or an alicyclic carbodiimide compound is preferably used.

[0042] <Organic solvent> The adhesive composition of the present invention can further contain an organic solvent. The organic solvent used in the present invention is not particularly limited as long as it can dissolve the acid-modified polyolefin (a), epoxy resin (b), oligophenylene ether (c), and carbodiimide compound (d). Specifically, for example, aromatic hydrocarbons such as benzene, toluene, and xylene, aliphatic hydrocarbons such as hexane, heptane, octane, and decane, alicyclic hydrocarbons such as cyclohexane, cyclohexene, methylcyclohexane, and ethylcyclohexane, halogenated hydrocarbons such as trichloroethylene, dichloroethylene, chlorobenzene, and chloroform, alcohol solvents such as methanol, ethanol, isopropyl alcohol, butanol, pentanol, hexanol, propanediol, and phenol, ketone solvents such as acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isophorone, and acetophenone, cellosolves such as methyl cellosolve and ethyl cellosolve, ester solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, and butyl formate, glycol ether solvents such as ethylene glycol mono n-butyl ether, ethylene glycol monoiso-butyl ether, ethylene glycol mono tert-butyl ether, diethylene glycol mono n-butyl ether, diethylene glycol monoiso-butyl ether, triethylene glycol mono n-butyl ether, and tetraethylene glycol mono n-butyl ether, etc. can be used, and one or more of these can be used in combination. Particularly, from the viewpoints of working environment and drying property, methylcyclohexane and toluene are preferred.

[0043] The organic solvent is preferably in the range of 100 to 1000 parts by mass, more preferably in the range of 200 to 900 parts by mass, and most preferably in the range of 300 to 800 parts by mass with respect to 100 parts by mass of the acid-modified olefin (a). By setting it to be not less than the lower limit value, the liquidity and pot life are improved. Also, by setting it to be not more than the upper limit value, it is advantageous in terms of manufacturing cost and transportation cost.

[0044] From the viewpoints of the solution state and pot life property of the adhesive composition, a mixed liquid of one or more solvents (e1) selected from the group consisting of aromatic hydrocarbons, aliphatic hydrocarbons, alicyclic hydrocarbons and halogenated hydrocarbons, and one or more solvents (e2) selected from the group consisting of alcohol solvents, ketone solvents, ester solvents and glycol ether solvents is preferred. As the mixing ratio, it is preferably solvent (e1) / solvent (e2)=50-97 / 50-3 (mass ratio), more preferably 55-95 / 45-5 (mass ratio), still more preferably 60-90 / 40-10 (mass ratio), and particularly preferably 70-80 / 30-20 (mass ratio). By setting it within the above range, the solution state and pot life property of the adhesive composition become good. Further, it is particularly preferable that the solvent (e1) is an aromatic hydrocarbon or an alicyclic hydrocarbon and the solvent (e2) is a ketone solvent.

[0045] In addition, the adhesive composition of the present invention may further contain other components as necessary within a range not impairing the effects of the present invention. Specific examples of such components include flame retardants, tackifiers, fillers, and silane coupling agents.

[0046] <Flame retardant> The adhesive composition of the present invention may contain a flame retardant as necessary within a range not impairing the effects of the present invention. Examples of the flame retardant include bromine-based, phosphorus-based, nitrogen-based, metal hydroxide compounds, etc. Among them, phosphorus-based flame retardants are preferred, and known phosphorus-based flame retardants such as phosphate esters (e.g., trimethyl phosphate, triphenyl phosphate, tricresyl phosphate, etc.), phosphates (e.g., aluminum phosphinate, etc.), and phosphazenes can be used. These may be used alone or in any combination of two or more. When containing a flame retardant, it is preferably contained in the range of 1-200 parts by mass, more preferably 5-150 parts by mass, and most preferably 10-100 parts by mass based on 100 parts by mass in total of the components (a)-(d). By setting it above the lower limit value, the flame retardancy becomes good. Also, by setting it below the upper limit value, the adhesiveness, solder heat resistance, electrical properties, etc. will not deteriorate.

[0047] <Adhesion promoter In the adhesive composition of the present invention, an adhesion promoter may be blended as necessary within a range that does not impair the effects of the present invention. Examples of the adhesion promoter include polyterpene resin, rosin resin, aliphatic petroleum resin, alicyclic petroleum resin, copolymerized petroleum resin, styrene resin, and hydrogenated petroleum resin, etc., and they are used for the purpose of improving the adhesive strength. These may be used alone or in any combination of two or more. When containing an adhesion promoter, it is preferably contained in the range of 1 to 200 parts by mass, more preferably in the range of 5 to 150 parts by mass, and most preferably in the range of 10 to 100 parts by mass with respect to 100 parts by mass in total of components (a) to (d). By setting it to be equal to or higher than the lower limit value, the effect of the adhesion promoter can be achieved. Also, by setting it to be equal to or lower than the upper limit value, the adhesiveness, solder heat resistance, electrical characteristics, etc. will not deteriorate.

[0048] <Filler In the adhesive composition of the present invention, a filler such as silica may be blended as necessary within a range that does not impair the effects of the present invention. Blending silica is very preferable because the characteristics of solder heat resistance are improved. Generally, hydrophobic silica and hydrophilic silica are known as silica, but here, hydrophobic silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane, etc. is better in terms of imparting moisture absorption resistance. When containing silica, its content is preferably in the range of 0.05 to 30 parts by mass with respect to 100 parts by mass in total of components (a) to (d). By setting it to be equal to or higher than the lower limit value, the effect of improving the solder heat resistance can be achieved. Also, by setting it to be equal to or lower than the upper limit value, poor dispersion of silica does not occur, the solution viscosity is good, and the workability is good. Also, the adhesiveness does not decrease.

[0049] <Silane coupling agent In the adhesive composition of the present invention, a silane coupling agent may be blended as necessary within a range that does not impair the effects of the present invention. Blending a silane coupling agent is very preferable because it improves the adhesion to metals and the characteristics of solder heat resistance. The silane coupling agent is not particularly limited, and examples include those having an unsaturated group, those having a glycidyl group, and those having an amino group. Among these, from the viewpoint of solder heat resistance, silane coupling agents having a glycidyl group such as γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltriethoxysilane are more preferable. When containing a silane coupling agent, its content is preferably in the range of 0.5 to 20 parts by mass with respect to 100 parts by mass in total of components (a) to (d). By setting it to 0.5 part by mass or more, excellent solder heat resistance is achieved. On the other hand, by setting it to 20 parts by mass or less, good solder heat resistance and adhesiveness are achieved.

[0050] <Laminate> The laminate of the present invention is one in which an adhesive composition is laminated on a base material (a two-layer laminate of a base material / adhesive layer), or one in which another base material is further laminated (a three-layer laminate of a base material / adhesive layer / base material). Here, the adhesive layer refers to a layer of the adhesive composition of the present invention after being applied to a base material and dried. The laminate of the present invention can be obtained by applying and drying the adhesive composition of the present invention to various base materials according to a conventional method, and further laminating another base material.

[0051] <Base material> In the present invention, the base material is not particularly limited as long as it can form an adhesive layer by applying and drying the adhesive composition of the present invention, and examples include resin base materials such as film-like resins, metal base materials such as metal plates and metal foils, and papers.

[0052] Examples of the resin base material include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, and fluororesin. Preferably, it is a film-shaped resin (hereinafter also referred to as a base film layer).

[0053] As the metal base material, any conventionally known conductive material that can be used for a circuit board can be used. Examples of the material include various metals such as SUS, copper, aluminum, iron, steel, zinc, nickel, and their respective alloys, plated products, and metals treated with other metals such as zinc and chromium compounds. Preferably, it is a metal foil, more preferably a copper foil. There is no particular limitation on the thickness of the metal foil, but preferably it is 1 μm or more, more preferably 3 μm or more, and even more preferably 10 μm or more. Also, preferably it is 50 μm or less, more preferably 30 μm or less, and even more preferably 20 μm or less. If the thickness is too thin, it may be difficult to obtain sufficient electrical performance of the circuit. On the other hand, if the thickness is too thick, the processing efficiency during circuit fabrication may decrease. The metal foil is usually provided in a roll form. The form of the metal foil used when manufacturing the printed wiring board of the present invention is not particularly limited. When using a metal foil in a ribbon form, its length is not particularly limited. Also, its width is not particularly limited, but it is preferably about 250 to 500 cm.

[0054] Examples of the papers include high-quality paper, kraft paper, roll paper, glassine paper, etc. Also, examples of the composite material include glass epoxy, etc.

[0055] From the adhesive strength and durability with the adhesive composition, as the base material, polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, fluororesin, SUS steel plate, copper foil, aluminum foil, or glass epoxy is preferable.

[0056] <Subsequent sheet> In the present invention, the adhesive sheet is formed by laminating the laminate and the release base material via an adhesive composition. Specific configurations include laminate / adhesive layer / release base material, or release base material / adhesive layer / laminate / adhesive layer / release base material. By laminating the release base material, it functions as a protective layer for the base material. Also, by using the release base material, the release base material can be released from the adhesive sheet, and the adhesive layer can be transferred to another base material.

[0057] The adhesive sheet of the present invention can be obtained by applying and drying the adhesive composition of the present invention to various laminates according to a conventional method. Also, after drying, when a release base material is attached to the adhesive layer, it can be wound up without causing back transfer to the base material, which is excellent in workability. Moreover, since the adhesive layer is protected, it is excellent in storage stability and easy to use. Also, after applying and drying on the release base material, if another release base material is attached as needed, it is possible to transfer the adhesive layer itself to another base material.

[0058] <Release base material> The release base material is not particularly limited. For example, coating layers of blocking agents such as clay, polyethylene, and polypropylene are provided on both sides of papers such as high-quality paper, kraft paper, roll paper, and glassine paper, and a silicone-based, fluorine-based, or alkyd-based release agent is further applied on each coating layer. Also, various olefin films alone such as polyethylene, polypropylene, ethylene-α-olefin copolymer, and propylene-α-olefin copolymer, and those with the above release agent applied on films such as polyethylene terephthalate are also included. Due to reasons such as the release force between the release base material and the adhesive layer and the adverse effect of silicone on electrical properties, those with polypropylene blocking treatment on both sides of high-quality paper and an alkyd-based release agent used thereon, or those with an alkyd-based release agent used on polyethylene terephthalate are preferred.

[0059] In the present invention, the method for coating the adhesive composition on the substrate is not particularly limited, and examples include comma coater, reverse roll coater, etc. Alternatively, if necessary, an adhesive layer can be provided directly or by a transfer method on a rolled copper foil or a polyimide film, which are constituent materials of a printed wiring board. The thickness of the adhesive layer after drying can be appropriately changed as needed, but is preferably in the range of 5 to 200 μm. If the adhesive film thickness is less than 5 μm, the adhesive strength is insufficient. If it is 200 μm or more, there are problems such as insufficient drying, an increase in residual solvent, and blistering during the pressing of the printed wiring board. The drying conditions are not particularly limited, but the residual solvent rate after drying is preferably 1% by mass or less. If it exceeds 1% by mass, there is a problem that the residual solvent foams during the pressing of the printed wiring board, causing blistering.

[0060] <Printed Wiring Board> The "printed wiring board" in the present invention includes, as a constituent element, a laminate formed from a metal foil for forming a conductor circuit and a resin substrate. The printed wiring board is manufactured, for example, by a conventionally known method such as a subtractive method using a metal-clad laminate. If necessary, so-called flexible circuit boards (FPCs), flat cables, circuit boards for tape automated bonding (TAB), etc., in which the conductor circuit formed by the metal foil is partially or entirely covered with a cover film, screen printing ink, etc., are collectively referred to.

[0061] The printed wiring board of the present invention can have any laminated structure that can be adopted as a printed wiring board. For example, it can be a printed wiring board composed of four layers: a substrate film layer, a metal foil layer, an adhesive layer, and a cover film layer. Also, for example, it can be a printed wiring board composed of five layers: a substrate film layer, an adhesive layer, a metal foil layer, an adhesive layer, and a cover film layer.

[0062] Furthermore, if necessary, the above printed wiring boards can be laminated in two or three or more layers.

[0063] The adhesive composition of the present invention can be suitably used for each adhesive layer of a printed wiring board. In particular, when the adhesive composition of the present invention is used as an adhesive, it has high adhesiveness not only with conventional polyimide, polyester film, and copper foil that constitute a printed wiring board, but also with low-polarity resin substrates such as LCP, and can obtain solder reflow resistance, and the adhesive layer itself has excellent low dielectric characteristics. Therefore, it is suitable as an adhesive composition used for a cover film, a laminate, a copper foil with resin, and a bonding sheet.

[0064] In the printed wiring board of the present invention, as the base film, any resin film that has been conventionally used as a base material for a printed wiring board can be used. Examples of the resin of the base film include polyester resin, polyamide resin, polyimide resin, polyamideimide resin, liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, polyolefin resin, and fluororesin. In particular, it has excellent adhesiveness even with low-polarity base materials such as liquid crystal polymer, polyphenylene sulfide, syndiotactic polystyrene, and polyolefin resin.

[0065] <Cover film> As the cover film, any insulating film conventionally known as an insulating film for a printed wiring board can be used. For example, films made of various polymers such as polyimide, polyester, polyphenylene sulfide, polyethersulfone, polyetheretherketone, aramid, polycarbonate, polyarylate, polyamideimide, liquid crystal polymer, syndiotactic polystyrene, and polyolefin resin can be used. More preferably, it is a polyimide film or a liquid crystal polymer film.

[0066] The printed wiring board of the present invention can be manufactured using any conventionally known process except for using the materials of the above-described layers.

[0067] In a preferred embodiment, a semi-finished product (hereinafter referred to as "cover film side semi-finished product") in which an adhesive layer is laminated on a cover film layer is manufactured. On the other hand, a semi-finished product in which a metal foil layer is laminated on a base film layer to form a desired circuit pattern (hereinafter referred to as "base film side two-layer semi-finished product") or a semi-finished product in which an adhesive layer is laminated on a base film layer and a metal foil layer is laminated thereon to form a desired circuit pattern (hereinafter referred to as "base film side three-layer semi-finished product") is manufactured (hereinafter, the base film side two-layer semi-finished product and the base film side three-layer semi-finished product are collectively referred to as "base film side semi-finished product"). By bonding the cover film side semi-finished product and the base film side semi-finished product thus obtained, a four-layer or five-layer printed wiring board can be obtained.

[0068] The base film side semi-finished product can be obtained, for example, by a manufacturing method including: (A) a step of applying a solution of a resin to be a base film to the metal foil and initially drying the coating film; and (B) a step of heat-treating and drying the laminate of the metal foil and the initially dried coating film obtained in (A) (hereinafter referred to as "heat treatment and desolvent removal step").

[0069] For forming a circuit in the metal foil layer, a conventionally known method can be used. An additive method may be used, or a subtractive method may be used. Preferably, it is a subtractive method.

[0070] The obtained base film side semi-finished product may be directly used for bonding with the cover film side semi-finished product, or may be bonded with a release film for storage and then used for bonding with the cover film side semi-finished product.

[0071] The cover film side semi-finished product is manufactured, for example, by applying an adhesive to the cover film. If necessary, a cross-linking reaction in the applied adhesive can be carried out. In a preferred embodiment, the adhesive layer is semi-cured.

[0072] The obtained cover film side semi-finished product may be directly used for lamination with the base film side semi-finished product, or may be used for lamination with the base film side semi-finished product after laminating and storing with a release film.

[0073] The base film side semi-finished product and the cover film side semi-finished product are each stored in the form of a roll, for example, and then laminated to produce a printed wiring board. As a lamination method, any method can be used. For example, lamination can be performed using a press or a roll. Also, the two can be laminated while heating by a method such as using a hot press or a heating roll device.

[0074] In the case of a reinforcing material side semi-finished product made of a soft rollable reinforcing material such as a polyimide film, for example, it is preferably produced by applying an adhesive to the reinforcing material. Also, in the case of a reinforcing plate that cannot be rolled up hard, such as a metal plate such as SUS or aluminum, or a plate obtained by curing glass fibers with an epoxy resin, it is preferably produced by transfer coating an adhesive previously applied to a release base material. Also, if necessary, a cross-linking reaction in the applied adhesive can be carried out. In a preferred embodiment, the adhesive layer is semi-cured.

[0075] The obtained reinforcing material side semi-finished product may be directly used for lamination with the back surface of the printed wiring board, or may be used for lamination with the base film side semi-finished product after laminating and storing with a release film.

[0076] The base film side semi-finished product, the cover film side semi-finished product, and the reinforcing material side semi-finished product are all laminates for printed wiring boards in the present invention.

[0077] <Example> Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the examples. In the examples and comparative examples, "parts" simply indicates parts by mass.

[0078] (Physical Property Evaluation Method)

[0079] Acid value (mgKOH / g) The acid value (mgKOH / g) in the present invention was obtained by dissolving the acid-modified polyolefin in toluene and titrating it with a methanol solution of sodium methoxide using phenolphthalein as an indicator.

[0080] Number average molecular weight (Mn) The number average molecular weight in the present invention is a value measured by gel permeation chromatography manufactured by Shimadzu Corporation (hereinafter referred to as GPC, standard substance: polystyrene resin, mobile phase: tetrahydrofuran, column: Shodex KF-802 + KF-804L + KF-806L, column temperature: 30 ° C, flow rate: 1.0 ml / min, detector: RI detector).

[0081] Measurement of melting point (Tm) and heat of fusion (ΔH) The melting point and heat of fusion in the present invention were measured from the top temperature and area of the melting peak when the temperature was raised for melting, cooled and resinified at a rate of 20 ° C / min and then the temperature was raised again for melting using a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instruments Japan, Q-2000).

[0082] (1) Peel strength (adhesion) The adhesive composition described below was applied to a polyimide film with a thickness of 12.5 μm (manufactured by Kaneka Corporation, Apical (registered trademark)) or an LCP film with a thickness of 25 μm (manufactured by Kuraray Co., Ltd., Vector (registered trademark)) so that the dried thickness became 25 μm, and dried at 130 ° C for 3 minutes. The adhesive film (B-stage product) thus obtained was bonded to a rolled copper foil with a thickness of 18 μm (manufactured by JX Metals Co., Ltd., BHY series). The bonding was carried out by pressing at 160 ° C under a pressure of 40 kgf / cm 2 for 30 seconds and bonding. Then, it was heat-treated at 140 ° C for 4 hours to be cured, and a sample for peel strength evaluation was obtained. The peel strength was measured by performing a 90 ° peel test at 25 ° C with a film pull and a tensile speed of 50 mm / min. This test indicates the adhesive strength at room temperature. <Evaluation Criteria> ◎: 1.0 N / mm or more ○: 0.8 N / mm or more and less than 1.0 N / mm △: 0.5 N / mm or more and less than 0.8 N / mm ×: Less than 0.5 N / mm

[0083] (2) Solder Heat Resistance Samples were prepared in the same manner as above. A 2.0 cm × 2.0 cm sample piece was subjected to an aging treatment at 23°C for 2 days, floated in a solder bath melted at 280°C for 10 seconds, and the presence or absence of appearance changes such as swelling was confirmed. <Evaluation Criteria> ◎: No swelling ○: Some swelling △: Considerable swelling ×: Swelling and discoloration

[0084] (3) Dielectric Constant (ε c 1) and Dissipation Factor (tanδ1) The adhesive composition described below was applied to a Teflon (registered trademark) sheet with a thickness of 100 μm so that the thickness after drying and curing would be 25 μm, and dried at 130°C for 3 minutes. Then, it was heat-treated at 140°C for 4 hours to be cured, and the Teflon (registered trademark) sheet was peeled off to obtain an adhesive resin sheet for testing. The obtained adhesive resin sheet for testing was cut into 8 cm × 3 mm strip-shaped samples to obtain test samples. The dielectric constant (ε c 1) and dissipation factor (tanδ1) were measured using a network analyzer (manufactured by Anritsu Corporation) under the conditions of a cavity resonator perturbation method at a temperature of 23°C and a frequency of 1 GHz. The measurement was performed within 1 hour after heat-treatment curing. The obtained dielectric constant and dissipation factor were evaluated as follows. <Evaluation Criteria for Dielectric Constant> ◎: 2.3 or less ○: Exceeding 2.3 and 2.6 or less △: Exceeding 2.6 and 3.0 or less ×: Exceeding 3.0 <Evaluation Criteria for Dissipation Factor> ◎: 0.008 or less ○: Exceeding 0.008 and 0.01 or less △: Greater than 0.01 and less than or equal to 0.02 ×: Greater than 0.02 (4) Dielectric tangent (tanδ2) after saturated water absorption The adhesive composition described below was applied to a Teflon (registered trademark) sheet with a thickness of 100 μm so that the thickness after drying and curing would be 25 μm, and dried at 130 °C for 3 minutes. Then, it was heat-treated at 140 °C for 4 hours to be cured, and then the Teflon (registered trademark) sheet was peeled off to obtain an adhesive resin sheet for testing. Next, the adhesive resin sheet for testing was immersed in water at 25 °C and left for 24 hours. Then, the moisture on the surface was wiped off, and the obtained adhesive resin sheet for testing was cut into samples in the shape of a strip of 8 cm × 3 mm to obtain test samples. The relative permittivity (ε c 2) and the dielectric tangent (tanδ2) were measured under the conditions of a temperature of 23 °C and a frequency of 1 GHz by the cavity resonator perturbation method using a network analyzer (manufactured by Anritsu Corporation). The change amount between the dielectric tangent (tanδ1) immediately after curing and the dielectric tangent (tanδ2) after saturated water absorption was obtained by the following formula and evaluated. Change amount = |(tanδ1) - (tanδ2)| <Evaluation criteria for the change amount of dielectric tangent> ◎: 0.002 or less 〇: Greater than 0.002 and less than or equal to 0.005 △: Greater than 0.005 and less than or equal to 0.01 ×: Greater than 0.01

[0085] Example 1 100 parts by mass of CO-1, 10 parts by mass of epoxy resin HP-7200H, and 440 parts by mass of an organic solvent (methylcyclohexane / methyl ethyl ketone / toluene = 72 / 8 / 20 (v / v)) were blended to obtain a mixed solution. The blending amounts, adhesive strength, solder heat resistance, electrical properties immediately after curing, and the change rate of the dielectric tangent after saturated water absorption are shown in Table 1.

[0086] Examples 2 to 16 (a)–(d) components were changed as shown in Table 1, and Examples 2–16 were carried out in the same manner as in Example 1. Adhesion strength, solder heat resistance, electrical properties immediately after curing, and the amount of change in dielectric tangent after saturation water absorption are shown in Table 1. The organic solvent (methylcyclohexane / methyl ethyl ketone / toluene = 72 / 8 / 20 (v / v)) was adjusted so that the solid content concentration was 20% by mass.

[0087]

Table 1

[0088] Comparative Examples 1–3 (a)–(d) components were changed as shown in Table 1, and Comparative Examples 1–3 were carried out in the same manner as in Example 1. Adhesion strength, solder heat resistance, electrical properties immediately after curing, and the rate of change in dielectric tangent after saturation water absorption are shown in Table 1.

[0089] The acid-modified polyolefin (a), epoxy resin (b), oligophenylene ether (c), and carbodiimide compound (d) used in Table 1 are as follows. (Epoxy resin (b)) Dicyclopentadiene-type epoxy resin: HP-7200 (manufactured by DIC Corporation, epoxy equivalent 259 g / eq) Dicyclopentadiene-type epoxy resin: HP-7200H (manufactured by DIC Corporation, epoxy equivalent 278 g / eq) Cresol novolac-type epoxy resin: jER-152 (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 177 g / eq Epoxy-modified polybutadiene resin: JP-100 (manufactured by Nippon Soda Co., Ltd., epoxy equivalent 200 g / eq) (Oligophenylene ether (c)) Styrene-modified oligophenylene ether: OPE-2St 1200 (manufactured by Mitsubishi Gas Chemical Company, compound having a structure of general formula (c4) with Mn 1000) Styrene-modified oligophenylene ether: OPE-2St 2200 (manufactured by Mitsubishi Gas Chemical Company, compound having a structure of general formula (c4) with Mn 2000) Oligophenylene ether: SA90 (a compound having the structure of general formula (c3) with Mn 1800 manufactured by SABIC) (carbodiimide compound (d)) Carbodiimide resin: V-09GB (manufactured by Nisshinbo Chemicals, carbodiimide equivalent 216 g / eq) Carbodiimide resin: V-03 (manufactured by Nisshinbo Chemicals, carbodiimide equivalent 209 g / eq)

[0090] (acid-modified polyolefin (a)) Production Example 1 Into a 1 L autoclave, 100 parts by mass of a propylene-butene copolymer ("Tafmer (registered trademark) XM7080" manufactured by Mitsui Chemicals), 150 parts by mass of toluene, 19 parts by mass of maleic anhydride, and 6 parts by mass of di-tert-butyl peroxide were added. After heating to 140°C, it was further stirred for 3 hours. Then, after cooling the obtained reaction solution, it was poured into a container containing a large amount of methyl ethyl ketone to precipitate the resin. Then, the solution containing the resin was centrifuged to separate and purify the acid-modified propylene-butene copolymer graft-polymerized with maleic anhydride, (poly) maleic anhydride, and low molecular weight substances. Then, it was dried at 70°C under reduced pressure for 5 hours to obtain a maleic anhydride-modified propylene-butene copolymer (CO-1, acid value 19 mgKOH / g, number average molecular weight 25,000, Tm 80°C, ΔH 35 J / g).

[0091] Production Example 2 A maleic anhydride-modified propylene-butene copolymer (CO-2, acid value 14 mgKOH / g, number average molecular weight 30,000, Tm 78°C, ΔH 25 J / g) was obtained in the same manner as in Production Example 1 except that the charged amount of maleic anhydride was changed to 14 parts by mass.

[0092] Production Example 3 A maleic anhydride-modified propylene-butene copolymer (CO-3, acid value 11 mgKOH / g, number average molecular weight 33,000, Tm 80°C, ΔH 25 J / g) was obtained in the same manner as in Production Example 1 except that the charged amount of maleic anhydride was changed to 11 parts by mass.

[0093] Production Example 4 An anhydride-modified propylene-butene copolymer (CO-4, acid value 7 mg KOH / g, number average molecular weight 35,000, Tm 82 °C, ΔH 25 J / g) was obtained in the same manner as in Production Example 1, except that the charged amount of maleic anhydride was changed to 6 parts by mass.

[0094] Production Example 5 An anhydride-modified propylene-butene copolymer (CO-5, acid value 4 mg KOH / g, number average molecular weight 37,000, Tm 84 °C, ΔH 25 J / g) was obtained in the same manner as in Production Example 1, except that the charged amount of maleic anhydride was changed to 3 parts by mass.

[0095] As is clear from Table 1, in Examples 1 to 16, all of the adhesiveness, solder heat resistance, electrical properties immediately after curing, and the amount of change in the dielectric tangent after saturated water absorption were good. On the other hand, in Comparative Example 1, the dielectric tangent immediately after curing and the amount of change in the dielectric tangent after saturated water absorption were poor. This is considered to be due to the high ratio of the epoxy resin (b). In Comparative Example 2, since the acid-modified polyolefin (a) was not contained, the electrical properties immediately after curing and the amount of change in the dielectric tangent after saturated water absorption were poor. In Comparative Example 3, since the epoxy resin (b) was not contained, the solder heat resistance decreased.

Industrial Applicability

[0096] The adhesive composition of the present invention has excellent adhesiveness between not only polyimide but also non-polar resin substrates such as liquid crystal polymers and metal substrates such as copper foils. It further has excellent solder heat resistance and low dielectric properties, and is also excellent in the dielectric tangent after saturated water absorption. The adhesive composition of the present invention can obtain an adhesive sheet and a laminate adhered using the same. Due to the above characteristics, it is useful in flexible printed wiring board applications, particularly in FPC applications where low dielectric properties (low relative dielectric constant, low dielectric tangent) in the high-frequency region are required.

Claims

1. An adhesive composition containing an acid-modified polyolefin (a) and an epoxy resin (b), wherein the acid value of the acid-modified polyolefin (a) is 5 to 40 mgKOH / g, the epoxy resin (b) is contained in an amount of 0.5 parts by mass or more and 60 parts by mass or less with respect to 100 parts by mass of the acid-modified polyolefin (a), further containing an oligophenylene ether (c), and satisfying the following (1) to (2). (1) The relative permittivity (εc1) at 1 GHz immediately after curing of the cured product of the adhesive composition is 3.0 or less, and the dielectric loss tangent (tanδ1) is 0.02 or less. (2) The change amount of the dielectric loss tangent (tanδ1) at 1 GHz immediately after curing of the cured product of the adhesive composition and the dielectric loss tangent (tanδ2) at 1 GHz after immersion in water at 25°C for 24 hours is 0.01 or less.

2. The adhesive composition according to Claim 1, further containing a carbodiimide compound (d).

3. An adhesive sheet having a layer containing the adhesive composition according to Claim 1 or 2.

4. A laminate having a layer containing the adhesive composition according to Claim 1 or 2.

5. A printed wiring board including the laminate according to Claim 4 as a component.

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