TWI853123B - Adhesive composition, adhesive sheet, laminate, and printed wiring board - Google Patents

Abstract

The subject of the present invention is to provide an adhesive composition having high adhesion not only to known polyimide and polyester films, but also to resin substrates such as liquid crystal polymers and polystyrene, and to metal substrates, and having high solder heat resistance, low dielectric properties, and excellent shelf life properties. The solution to this problem is an adhesive composition containing: acid-modified polyolefin (a), phenolic resin with a polycyclic structure (b), and epoxy resin (c).

Description

Adhesive composition, adhesive sheet, laminate, and printed wiring board

The present invention relates to an adhesive composition. More specifically, it relates to an 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 referred to as FPC), and to an adhesive sheet, a laminate and a printed wiring board containing the adhesive composition.

Flexible printed circuit boards (FPCs) are often used to fit electronic circuit boards into small and complex interiors because they have excellent flexibility and can accommodate the multifunctionality and miniaturization of personal computers (PCs) and smart phones. In recent years, electronic equipment has been miniaturized, lightweight, high-density, and high-output, and their popularity has led to an increasing demand for the performance of wiring boards (electronic circuit boards). In particular, with the increase in the speed of transmission signals in FPCs, the frequency of signals is increasing. As a result, the requirements for low dielectric properties (low dielectric constant, low dielectric loss tangent) in the high-frequency region of FPCs have increased. In addition, for the substrate used in FPC, not only the known polyimide (PI) and polyethylene terephthalate (PET) have been proposed, but also substrate films such as liquid crystal polymer (LCP) and parallel polystyrene (SPS) with low dielectric properties have been proposed. In order to achieve such low dielectric properties, there are methods for reducing the dielectric loss of the substrate and adhesive of the FPC. As for the adhesive, the development of a combination of polyolefin and epoxide (patent document 1) or a combination of elastomer and epoxide (patent document 2) is in progress. [Prior technical literature] [Patent literature]

[Patent document 1] WO2016/047289 [Patent document 2] WO2014/147903

[The problem that the invention wants to solve]

However, the heat resistance of the adhesive used in the reinforcing plate and between the layers of Patent Document 1 is not good. Also, the storage stability after mixing, which is important in the use of Patent Document 2, is insufficient.

The present invention has been made after in-depth research to solve the above-mentioned problems. As a result, it has been found that the adhesive composition with a specific composition has high adhesion not only to the known polyimide film, but also to resin substrates such as liquid crystal polymers or polystyrene and metal substrates such as copper foil. In addition, it has low dielectric properties (electrical properties), solder heat resistance, and excellent usable life characteristics after mixing, thus completing the present invention.

That is, the purpose of the present invention is to provide an adhesive composition that has good adhesion not only to polyimide but also to various resin substrates such as liquid crystal polymers or polystyrene and metal substrates, and has excellent low dielectric properties (electrical properties), solder heat resistance, and shelf life properties. [Means for solving the problem]

An adhesive composition comprises: acid-modified polyolefin (a), phenolic resin having a polycyclic structure (b), and epoxy resin (c).

The polycyclic phenolic resin (b) is preferably a phenolic resin having a tricyclic decane skeleton, and preferably has a carbonate skeleton. The acid value of the acid-modified polyolefin (a) is preferably 5-40 mgKOH/g.

Furthermore, relative to 100 parts by weight of the acid-modified polyolefin (a), preferably 0.05 to 120 parts by weight of the phenolic resin (b) having a polycyclic structure, 0.1 to 60 parts by weight of the epoxy resin (c), and 0.1 to 30 parts by weight of the polycarbodiimide (d) are contained.

The adhesive composition preferably has a relative dielectric constant (ε _c ) of 3.0 or less and a dielectric loss tangent (tan δ) of 0.02 or less at 1 GHz.

An adhesive sheet or laminate containing the aforementioned adhesive composition. A printed wiring board containing the aforementioned laminate as a constituent element. [Effect of the invention]

The adhesive composition of the present invention has good adhesion not only to polyimide but also to various resin substrates such as liquid crystal polymer or polystyrene and metal substrates, and has low dielectric properties (electrical properties), solder heat resistance, and excellent pot life properties.

<Acid-modified polyolefin (a)> The acid-modified polyolefin (a) (hereinafter also referred to as component (a)) used in the present invention is not limited, and is preferably obtained by grafting at least one of α,β-unsaturated carboxylic acid and its anhydride to a polyolefin resin. Polyolefin resin refers to a homopolymer of an olefin monomer such as ethylene, propylene, butene, butadiene, isoprene, etc., or a copolymer with other monomers, and a polymer such as a hydrogenate or halogenide of the obtained polymer, which has a hydrocarbon skeleton as the main body. That is, the acid-modified polyolefin is preferably obtained by grafting at least one of α,β-unsaturated carboxylic acid and its anhydride to at least one of polyethylene, polypropylene, and propylene-α-olefin copolymer.

The propylene-α-olefin copolymer is a copolymer made of propylene as the main component and α-olefin copolymerized thereon. The α-olefin may be, for example, one or more of ethylene, 1-butene, 1-heptene, 1-octene, 4-methyl-1-pentene, vinyl acetate, etc. Among these α-olefins, ethylene and 1-butene are preferred. The ratio of the propylene component to the α-olefin component of the propylene-α-olefin copolymer is not limited, but the propylene component is preferably 50 mol% or more, and more preferably 70 mol% or more.

At least one of the α,β-unsaturated carboxylic acids and their anhydrides can be exemplified by maleic acid, itaconic acid, liraconic acid and their anhydrides. Among them, 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 exemplified. These acid-modified polyolefins can be used alone or in combination of two or more.

The acid value of the acid-modified polyolefin (a) should preferably be 5 mgKOH/g or more, preferably 6 mgKOH/g or more, and even more preferably 7 mgKOH/g or more, from the viewpoint of heat resistance and adhesion to resin substrates and metal substrates. By setting it above the aforementioned lower limit, the compatibility with the epoxy resin (c) can be improved, and excellent bonding strength can be exhibited. In addition, the crosslinking density is high and the solder heat resistance is improved. The upper limit should preferably be 40 mgKOH/g or less, preferably 30 mgKOH/g or less, and even more preferably 20 mgKOH/g or less. By setting it below the aforementioned upper limit, the adhesion will be improved. In addition, the viscosity and stability of the solution will be improved, and excellent pot life characteristics can be exhibited. In addition, the manufacturing efficiency will also be improved.

The number average molecular weight (Mn) of the acid-modified polyolefin (a) is preferably in the range of 10,000 to 50,000. It is more preferably in the range of 15,000 to 45,000, 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 above the aforementioned lower limit, the cohesive force can be improved and excellent adhesion can be exhibited. In addition, by setting it to be below the aforementioned upper limit, the fluidity is excellent and the operability is good.

The acid-modified polyolefin (a) is preferably a crystalline acid-modified polyolefin. The term "crystalline" as used in the present invention means that the polyolefin exhibits a clear melting peak during the temperature rise from -100°C to 250°C at 20°C/min using a differential scanning calorimeter (DSC).

The melting point (Tm) of the acid-modified polyolefin (a) is preferably in the range of 50°C to 120°C. It is more preferably 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 above the aforementioned lower limit, the cohesive force derived from crystallization can be improved, and excellent adhesion and solder heat resistance can be exhibited. In addition, by setting it to be below the aforementioned upper limit, the solution stability and fluidity are excellent, and the workability during bonding is good.

The heat of fusion (ΔH) of the acid-modified polyolefin (a) is preferably in the range of 5 J/g to 60 J/g. It is more preferably 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 above the aforementioned lower limit, the cohesive force derived from crystallization can be improved, and excellent adhesion and solder heat resistance can be exhibited. In addition, by setting it to be below the aforementioned upper limit, the solution stability and fluidity are excellent, and the workability during bonding is good.

The method for producing the acid-modified polyolefin (a) is not particularly limited, and examples thereof include free radical grafting reaction (i.e., a reaction in which free radical species are generated for a polymer as a main chain, and unsaturated carboxylic acid and anhydride are grafted and polymerized using the free radical species as a polymerization starting point).

There is no particular restriction on the free radical generator, but it is preferred to use an organic peroxide. There is no particular restriction on the organic peroxide, and examples thereof include: di(tertiary butyl) peroxyphthalate, tertiary butyl hydroperoxide, diisopropylbenzene peroxide, benzoyl peroxide, tertiary butyl peroxybenzoate, tertiary butyl peroxy-2-ethylhexanoate, tertiary butyl peroxytrimethylacetate, methyl ethyl ketone peroxide, di(tertiary butyl) peroxide, lauryl peroxide and other peroxides; azo nitriles such as azobisisobutylonitrile and azobisisopropionitrile, etc.

<Phenolic resin (b) with polycyclic structure> The phenolic resin (b) with polycyclic structure used in the present invention (hereinafter also referred to as component (b)) is not limited as long as it has one or more polycyclic structures in one molecule. A polycyclic structure refers to a structure formed by bonding multiple ring structures mainly composed of carbon, and examples thereof include: aromatic skeletons such as naphthalene, anthracene, dihydroindene, tetrahydronaphthalene; structures with alicyclic skeletons such as decahydronaphthalene, norbornane, tricyclodecane, etc. By having a polycyclic structure, the free volume of the resin increases and low dielectric properties are exhibited. In addition, heat resistance is exhibited. The number of polycyclic structures contained in one molecule is preferably 2 or more, and more preferably 3 or more. Furthermore, it is preferably 10 or less, more preferably 8 or less, and even more preferably 5 or less. By setting it within the above range, excellent dielectric properties can be exhibited. The polycyclic structure is not particularly limited, and is preferably an alicyclic skeleton with 4 to 30 carbon atoms, more preferably an alicyclic skeleton with 5 to 25 carbon atoms, even more preferably an alicyclic skeleton with 8 to 20 carbon atoms, and particularly preferably an alicyclic skeleton with 10 to 15 carbon atoms. Specific examples of the polycyclic structure include: bicyclic alicyclic structures such as dicyclobutane, dicyclopentane, dicyclohexane, dicycloheptane (norbornane), dicyclooctane, dicyclononane, and dicyclodecane, which may optionally have substituents; tricyclic alicyclic structures such as tricyclooctane, tricyclononane, tricyclodecane, tricycloundecane, and tricyclododecane, which may optionally have substituents; alicyclic structures having four or more rings such as tetracyclodecane, tetracycloundecane, and tetracyclododecane, which may optionally have substituents; and aromatic structures such as naphthalene, anthracene, dihydroindene, and tetrahydronaphthalene, which may optionally have substituents. In addition, the aforementioned alicyclic structure may also have an unsaturated bond, and examples thereof include bicycloheptene, bicyclohexene, bicycloheptene, bicyclooctene, bicyclononene, bicyclodecene, etc., which may also have a substituent. One molecule of the phenolic resin may have one of these polycyclic structures, or two or more of them. The aforementioned substituent is not particularly limited, and examples thereof include alkyl groups such as methyl, ethyl, and propyl; alkoxy groups such as methoxy and ethoxy; thioalkoxy groups such as thiomethoxy and thioethoxy; hydroxyl groups, amino groups, etc.

Among the aforementioned polycyclic structures, tricyclic alicyclic structures such as tricyclooctane, tricyclononane, tricyclodecane, tricycloundecane and tricyclododecane which may have a substituent are preferred, and tricyclodecane which may have a substituent is more preferred. Among them, tricyclo[5.2.1.0 ^2,6 ]decane, tricyclo[6.1.1.0 ^{2,6 ]decane, tricyclo[6.1.1.0 2,7 ]decane and tricyclo[3.3.1.1 3,7 ] decane} (adamantane) which may have a substituent are preferred, and tricyclo[5.2.1.0 ^2,6 ]decane which may have a substituent is particularly preferred. Specifically, the following can be cited: 3,4-dimethylenetricyclo[5.2.1.0 ^2,6 ]decane, 3,5-dimethylenetricyclo[5.2.1.0 ^2,6 ]decane, 3,8-dimethylenetricyclo[5.2.1.0 ^2,6 ]decane, 3,9-dimethylenetricyclo[5.2.1.0 2,6 ]decane, 8,9-dimethylenetricyclo[5.2.1.0 ^2,6 ]decane, among which 3,5-dimethylenetricyclo[5.2.1.0 ^2,6 ]decane is ^preferred .

The phenolic resin (b) having a polycyclic structure preferably has a carbonate skeleton. By having a carbonate skeleton, the adhesiveness and electrical properties can be maintained, and flexibility can be given to the adhesive composition. The number of carbonate skeletons contained in the phenolic resin (b) having a polycyclic structure is preferably 2 or more, more preferably 3 or more, and more preferably 4 or more in one molecule. In addition, it is preferably 10 or less, more preferably 8 or less, and more preferably 6 or less.

The phenolic resin (b) having a polycyclic structure preferably has a structure represented by the general formula (1). In the general formula (1), m and n are preferably independently integers of 1 to 10, more preferably 8 or less, even more preferably 5 or less, and particularly preferably 2 or less.

Furthermore, the phenolic resin (b) having a polycyclic structure is more preferably of the general formula (2). In the general formula (2), m and n have the same meanings as above. p is preferably an integer of 1 to 10, more preferably 2 or more, even more preferably 3 or more, and particularly preferably 4 or more. It is preferably 8 or less, even more preferably 5 or less. R ₁ and R ₂ are each independently an aromatic hydrocarbon which may have a substituent, and the substituent is preferably an aliphatic hydrocarbon which may have a further substituent, an alicyclic hydrocarbon which may have a further substituent, or an aromatic hydrocarbon which may have a further substituent.

The aforementioned R ₁ and R ₂ are preferably independently a group having a structure of formula (11) or formula (12). [Chemistry 4] In formula (11) and formula (12), R ₃ and R ₄ are preferably independently an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, an alkenyl group having 2 to 10 carbon atoms, or a phenyl group which may have a substituent. It is more preferably an alkyl group having 1 to 5 carbon atoms or an alkenyl group having 1 to 5 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms or an alkenyl group having 2 to 3 carbon atoms. Specifically, it is preferably a methyl group, an ethyl group, an n-propyl group, an isopropyl group, or a propenyl group. x and y are each independently an integer of 0 to 4, preferably an integer of 0 to 3, more preferably 0 or 1, and particularly preferably 1. Z ₁ is preferably an integer of 0 to 5, more preferably an integer of 1 to 3, more preferably 1 or 2, and particularly preferably 1. Z ₂ is preferably an integer of 0 to 5, more preferably an integer of 1 to 3, more preferably 1 or 2, and particularly preferably 1. The hydroxyl group or ether group may be in the ortho, meta or para position with respect to the benzyl group, but is preferably in the para position. * represents an atomic bond with the oxygen atom of the general formula (2).

The number average molecular weight of the component (b) is preferably 5000 or less, more preferably 4000 or less, and even more preferably 3500 or less. In addition, the number average molecular weight of the component (b) is preferably 500 or more, and more preferably 700 or more. By setting the number average molecular weight of the component (b) to be above the lower limit, the flexibility of the obtained adhesive layer can be improved. On the other hand, by setting the number average molecular weight of the component (b) to be below the upper limit, the solubility in organic solvents can be improved.

The content of component (b) is preferably 0.05 parts by mass or more, more preferably 1 part by mass or more, and even more preferably 5 parts by mass or more relative to 100 parts by mass of component (a). By setting it to the above lower limit, excellent solder heat resistance can be exhibited. In addition, it is preferably 120 parts by mass or less, more preferably 100 parts by mass or less, even more preferably 90 parts by mass or less, and particularly preferably 80 parts by mass or less. By setting it to the above upper limit or less, excellent adhesion and solder heat resistance can be exhibited.

<Epoxy resin (c)> The epoxy resin (c) (hereinafter also referred to as component (c)) used in the present invention is not particularly limited as long as it has an epoxy group in the molecule, but it is preferably one having two or more epoxy groups in the molecule. Specifically, 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, novolac type epoxy resin, alicyclic epoxy resin, dicyclopentadiene type epoxy resin, tetracyclyl diamino diphenyl methane, tricyclyl p-aminophenol, tetracyclyl diamino methyl cyclohexanone, N,N,N',N'-tetracyclyl m-xylene diamine, and epoxy-modified polybutadiene can be used, but the present invention is not particularly limited. Preferably, it is a biphenyl type epoxy resin, a novolac type epoxy resin, a dicyclopentadiene type epoxy resin, triglycidyl p-aminophenol or epoxy-modified polybutadiene. More preferably, it is a dicyclopentadiene type epoxy resin, a novolac type epoxy resin or triglycidyl p-aminophenol.

In the adhesive composition of the present invention, the content of the epoxy resin (c) is preferably 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1 parts by mass or more, and particularly preferably 2 parts by mass or more relative to 100 parts by mass of the acid-modified polyolefin (a). By setting it to above the aforementioned lower limit, a sufficient curing effect can be obtained, and excellent adhesion and solder heat resistance can be exhibited. In addition, it is preferably 60 parts by mass or less, preferably 50 parts by mass or less, more preferably 40 parts by mass or less, and particularly preferably 35 parts by mass or less. By setting it to below the aforementioned upper limit, the usable period characteristics and low dielectric characteristics are good. That is, by setting the temperature within the above range, an adhesive composition having excellent low dielectric properties in addition to adhesion, solder heat resistance and shelf life properties can be obtained.

<Polycarbodiimide (d)> The polycarbodiimide (d) (hereinafter also referred to as component (d)) used in the present invention is not particularly limited as long as it has a carbodiimide group in the molecule. It is preferably a polycarbodiimide having two or more carbodiimide groups in the molecule. By using polycarbodiimide, the carboxyl group of the acid-modified polyolefin (a) reacts with the carbodiimide group, which can enhance the interaction between the adhesive composition and the substrate and improve the adhesion.

In the adhesive composition of the present invention, the content of polycarbodiimide (d) is preferably 0.1 parts by mass or more, preferably 0.5 parts by mass or more, more preferably 1 parts by mass or more, and particularly preferably 2 parts by mass or more relative to 100 parts by mass of the acid-modified polyolefin (a). By setting it to above the aforementioned lower limit, the interaction with the substrate will be exhibited, and the adhesion will become good. In addition, it is preferably 30 parts by mass or less, preferably 25 parts by mass or less, more preferably 20 parts by mass or less, more preferably 15 parts by mass or less, and particularly preferably 10 parts by mass or less. By setting it to below the aforementioned upper limit, excellent pot life characteristics and low dielectric characteristics can be exhibited. That is, by setting it within the above range, an adhesive composition having excellent low dielectric properties in addition to adhesion, solder heat resistance and shelf life characteristics can be obtained. In addition, with respect to the content of polycarbodiimide (d) relative to epoxy resin (c), it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more relative to 100 parts by mass of epoxy resin (c). In addition, it is preferably less than 100 parts by mass, more preferably less than 80 parts by mass, and even more preferably less than 60 parts by mass. By setting it within the above range, an adhesive composition having a good balance of solder heat resistance and low dielectric properties can be produced.

<Adhesive composition> The adhesive composition of the present invention can exhibit excellent adhesion, shelf life characteristics, electrical properties (low dielectric properties) and heat resistance with low polarity resin substrates such as liquid crystal polymer (LCP) and para-polystyrene (SPS), or metal substrates by containing the three resins of the aforementioned components (a) to (c). That is, when the adhesive composition is applied to the substrate, the cured adhesive coating film (adhesive layer) can exhibit excellent low dielectric constant characteristics.

The adhesive composition of the present invention may 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), the phenolic resin having a polycyclic structure (b), the epoxy resin (c), and the polycarbodiimide (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, isopropanol, butanol, pentanol, hexanol, propanediol, and phenol; acetone, methyl isobutyl ketone, methyl ethyl ketone, pentanone, hexanone, cyclohexanone, isobutyl alcohol, and butyl alcohol. Ketone solvents such as phorone and acetophenone; cellulosides such as methyl cellulosides and ethyl cellulosides; ester solvents such as methyl acetate, ethyl acetate, butyl acetate, methyl propionate, butyl formate; glycol ether solvents such as ethylene glycol mono-n-butyl ether, ethylene glycol mono-isobutyl ether, ethylene glycol mono-tertiary butyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-isobutyl ether, triethylene glycol mono-n-butyl ether, tetraethylene glycol mono-n-butyl ether, etc., and these can be used alone or in combination of two or more. In particular, considering the working environment and dryness, methylcyclohexane and toluene are preferred.

The amount of the organic solvent relative to 100 parts by mass of the acid-modified polyolefin (a) 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. By setting it to be above the lower limit, the liquid state and the pot life characteristics are good. In addition, by setting it to be below the upper limit, it is advantageous in terms of manufacturing cost and transportation cost.

The relative dielectric constant (ε _c ) of the adhesive composition of the present invention at a frequency of 1 GHz is preferably 3.0 or less, more preferably 2.6 or less, and even more preferably 2.3 or less. The lower limit is not particularly limited, and is 2.0 in practical use. Furthermore, the relative dielectric constant (ε) in the entire frequency range of 1 GHz to 60 GHz is preferably 3.0 or less, more preferably 2.6 or less, and even more preferably 2.3 or less.

The dielectric loss tangent (tanδ) of the adhesive composition of the present invention at a frequency of 1 GHz is preferably 0.02 or less. It is more preferably 0.01 or less, and even more preferably 0.008 or less. The lower limit is not particularly limited, and is 0.0001 in practical use. Moreover, the dielectric loss tangent (tanδ) 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 0.005 or less.

In the present invention, the relative dielectric constant (ε _c ) and the dielectric loss tangent (tan δ) can be measured as follows. That is, the adhesive composition is applied to the release substrate so that the thickness after drying becomes 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 harden, and the hardened adhesive composition layer (adhesive layer) is peeled off from the release film. The relative dielectric constant (ε _c ) and the dielectric loss tangent (tan δ) of the adhesive composition layer after peeling are measured at a frequency of 1 GHz. Specifically, the relative dielectric constant (ε _c ) and the dielectric loss tangent (tan δ) can be calculated from measurements using the resonant cavity perturbation method.

Furthermore, the adhesive composition of the present invention may contain other components as required. Specific examples of such components include flame retardants, adhesives, fillers, and silane coupling agents.

<Flame retardant> The adhesive composition of the present invention may also be blended with a flame retardant as needed. Flame retardants 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 (such as trimethyl phosphate, triphenyl phosphate, tricresol phosphate, etc.), phosphates (such as aluminum hypophosphite, etc.), and phosphazenes can be used. They can be used alone or in any combination of two or more. When containing a flame retardant, the content of the flame retardant is preferably in the range of 1 to 200 parts by mass, preferably in the range of 5 to 150 parts by mass, and most preferably in the range of 10 to 100 parts by mass, relative to 100 parts by mass of the total of components (a) to (d). By setting it within the above range, adhesion, solder heat resistance and electrical properties can be maintained, and flame retardancy can be exhibited.

<Binder> The adhesive composition of the present invention may also be blended with a binder as needed. Examples of binders include polyterpene resins, rosin resins, aliphatic petroleum resins, alicyclic petroleum resins, copolymerized petroleum resins, styrene resins, and hydrogenated petroleum resins, which can be used to improve the bonding strength. They can be used alone or in any combination of two or more. When a binder is contained, the binder content is preferably 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, relative to 100 parts by mass of the total of components (a) to (d). By setting it within the above range, the adhesiveness, solder heat resistance and electrical properties can be maintained, and the adhesive effect can be exhibited.

<Filler> The adhesive composition of the present invention may also be blended with fillers such as silica as needed. By blending silica, the heat resistance characteristics are improved, which is very ideal. Silica is generally known to have hydrophobic silica and hydrophilic silica. In terms of imparting moisture absorption resistance, hydrophobic silica treated with dimethyldichlorosilane, hexamethyldisilazane, octylsilane, etc. is preferred. When blending silica, the blending amount is preferably 0.05 to 30 parts by mass relative to 100 parts by mass of the total of components (a) to (d). By setting it above the aforementioned lower limit, further heat resistance can be exhibited. Furthermore, by setting the content to be equal to or less than the above upper limit, poor dispersion of silica or excessive increase in solution viscosity can be suppressed, thereby improving workability.

<Silane coupling agent> The adhesive composition of the present invention can also be mixed with a silane coupling agent as needed. By mixing with a silane coupling agent, the adhesion to metal or the heat resistance characteristics are improved, which is very ideal. There is no particular limitation on the silane coupling agent, and examples include: those with unsaturated groups, those with glycidyl groups, and those with amino groups. Among them, from the perspective of heat resistance, silane coupling agents with glycidyl groups such as γ-glycidoxypropyltrimethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, or β-(3,4-epoxycyclohexyl)ethyltriethoxysilane are more preferred. When the silane coupling agent is added, the amount of the silane coupling agent added is preferably 0.5 to 20 parts by weight relative to 100 parts by weight of the total of the components (a) to (d). By setting the amount within the above range, the heat resistance and adhesion of the solder can be improved.

<Laminated body> The laminated body of the present invention is formed by laminating an adhesive composition on a substrate (substrate/adhesive layer two-layer laminated body), or further laminating a substrate (substrate/adhesive layer/substrate three-layer laminated body). Here, the adhesive layer refers to the layer of the adhesive composition after applying the adhesive composition of the present invention to a substrate and drying it. The laminated body of the present invention can be obtained by applying the adhesive composition of the present invention to various substrates according to the conventional method and drying it, and further laminating it with other substrates.

<Substrate> The substrate in the present invention is not particularly limited as long as it can be coated with the adhesive composition of the present invention and dried to form an adhesive layer, and examples thereof include: resin substrates such as film-like resins, metal substrates such as metal plates or metal foils, and paper.

Examples of the resin substrate include polyester resins, polyamide resins, polyimide resins, polyamide imide resins, liquid crystal polymers, polyphenylene sulfide, para-polystyrene, polyolefin resins, and fluorine resins, etc. The resin substrate is preferably a film-like resin (hereinafter also referred to as a substrate film layer).

The metal substrate can use any known conductive material that can be used for circuit boards. Examples of the material include: SUS, copper, aluminum, iron, steel, zinc, nickel and other metals, and metals treated with other metals such as respective alloys, platings, zinc or chromium compounds, etc. It is preferably a metal foil, and copper foil is more preferred. The thickness of the metal foil is not particularly limited, and is preferably 1 μm or more, preferably 3 μm or more, and more preferably 10 μm or more. In addition, it is preferably 50 μm or less, preferably 30 μm or less, and more preferably 20 μm or less. When the thickness is too thin, sometimes it is difficult for the circuit to obtain sufficient electrical performance. On the other hand, when the thickness is too thick, sometimes the processing efficiency during circuit manufacturing is reduced. The metal foil is usually provided in the form of a roll. There is no particular restriction on the form of the metal foil used in the manufacture of the printed wiring board of the present invention. When a strip-shaped metal foil is used, there is no particular restriction on its length. In addition, there is no particular restriction on its width, and it is preferably about 250~500cm. There is no particular restriction on the surface roughness of the substrate, and it is preferably less than 3μm, preferably less than 2μm, and more preferably less than 1.5μm. In addition, in practice, it is preferably more than 0.3μm, more preferably more than 0.5μm, and more preferably more than 0.7μm. In addition, it is preferably less than 3μm, more preferably less than 2μm, and more preferably less than 1.5μm.

Examples of paper include high-quality paper, kraft paper, paper rolls, and cellophane. Examples of composite materials include glass epoxy resins and the like.

Considering the adhesion and durability of the adhesive composition, the substrate is preferably polyester resin, polyamide resin, polyimide resin, polyamide imide resin, liquid crystal polymer, polyphenylene sulfide, para-polystyrene, polyolefin resin, fluorine resin, SUS steel plate, copper foil, aluminum foil, or glass epoxy resin.

<Adhesive sheet> In the present invention, the adhesive sheet is a laminate of the aforementioned laminate and release substrate by means of an adhesive composition. Specific configurations may be listed as: laminate/adhesive layer/release substrate, or release substrate/adhesive layer/laminate/adhesive layer/release substrate. By laminating the release substrate, it functions as a protective layer for the substrate. Furthermore, by using the release substrate, the release substrate can be demolded from the adhesive sheet, and then the adhesive layer can be transferred to another substrate.

The adhesive sheet of the present invention can be obtained by applying the adhesive composition of the present invention to various laminated bodies according to the conventional method and drying. Moreover, if the adhesive layer is attached to the release substrate after drying, it can be rolled up without causing back printing to the substrate, and the workability is good. At the same time, the adhesive layer is protected, so the storage is good and it is easy to use. Moreover, if it is applied to the release substrate and dried, it is attached to another release substrate as needed, and the adhesive layer itself can also be transferred to other substrates.

<Release substrate> The release substrate is not particularly limited. Examples include those obtained by providing a coating layer of a filler such as clay, polyethylene, or polypropylene on both sides of high-quality paper, kraft paper, paper roll, or cellophane, and then applying a silicone-based, fluorine-based, or alkyd-based release agent on each coating layer. Examples include: polyethylene, polypropylene, ethylene-α-olefin copolymer, propylene-α-olefin copolymer, and other olefin films alone; and those obtained by applying the above-mentioned release agent on a film such as polyethylene terephthalate. Considering the release force of the release substrate and the adhesive layer, and the adverse effects of silicone on electrical properties, it is advisable to fill both sides of high-quality paper with polypropylene and then use an alkyd release agent on it, or to use an alkyd release agent on polyethylene terephthalate.

In addition, the method of coating the adhesive composition on the substrate in the present invention is not particularly limited, and can be listed as: jog coating, reverse roll coating, etc. Or it is also possible to directly set the adhesive layer on the rolled copper foil as a material constituting the printed wiring board, or on the polyimide film, or to set the adhesive layer by transfer method. The thickness of the adhesive layer after drying is appropriately changed according to the needs, and is preferably in the range of 5 to 200 μm. By setting the thickness of the adhesive film to more than 5 μm, sufficient bonding strength can be obtained. Furthermore, by setting the diameter to 200 μm or less, the residual solvent amount in the drying step can be easily controlled, and swelling is not likely to occur during pressing in the manufacture of printed wiring boards. There are no particular restrictions on drying conditions, and the residual solvent rate after drying is preferably 1% by mass or less. By setting the diameter to 1% by mass or less, bubbling of the residual solvent can be suppressed during pressing of printed wiring boards, and swelling is not likely to occur.

<Printed wiring board> The "printed wiring board" in the present invention includes a laminate formed of a metal foil forming a conductive circuit and a resin substrate as a constituent element. The printed wiring board is manufactured by, for example, using a metal-clad laminate and utilizing a known method such as a subtractive method. The so-called flexible printed circuit (FPC), flat cable, tape automated bonding (TAB) circuit board, etc., in which the conductive circuit formed by the metal foil is partially or fully covered with a covering film, screen printing ink, etc. as needed.

The printed wiring board of the present invention can be made into any laminated structure that can be used as a printed wiring board. For example, it can be made into a printed wiring board composed of four layers of a base film layer, a metal foil layer, an adhesive layer, and a cover film layer. In addition, it can be made into a printed wiring board composed of five layers of a base film layer, an adhesive layer, a metal foil layer, an adhesive layer, and a cover film layer.

Furthermore, a structure in which two or three or more of the above-mentioned printed wiring boards are stacked can be produced as needed.

The adhesive composition of the present invention can be ideally used in each adhesive layer of a printed wiring board. In particular, when the adhesive composition of the present invention is used as an adhesive, it not only has high adhesion to the known polyimide, polyester film, and copper foil constituting the printed wiring board, but also has high adhesion to low-polarity resin substrates such as LCP, and can obtain solder reflow resistance. The adhesive layer itself has excellent low dielectric properties. Therefore, it is suitable as an adhesive composition used for a cover film, a laminate, a copper foil with a resin, and an adhesive sheet.

In the printed wiring board of the present invention, the base film can use any resin film that has been used as a base material of the printed wiring board in the past. Examples of the resin of the base film include polyester resin, polyamide resin, polyimide resin, polyamide imide resin, liquid crystal polymer, polyphenylene sulfide, para-polystyrene, polyolefin resin, and fluorine resin. In particular, it has excellent adhesion to low-polarity base materials such as liquid crystal polymer, polyphenylene sulfide, para-polystyrene, and polyolefin resin.

<Coating film> The covering film may be any insulating film known as an insulating film for printed wiring boards. For example, films made of various polymers such as polyimide, polyester, polyphenylene sulfide, polyether sulfide, polyether ether ketone, aromatic polyamide, polycarbonate, polyarylate, polyamide imide, liquid crystal polymer, para-polystyrene, and polyolefin resin may be used. Polyimide film or liquid crystal polymer film is more preferred.

In addition to using the above-mentioned materials for each layer, the printed wiring board of the present invention can also be manufactured using any known process.

An ideal implementation is to manufacture a semi-finished product in which an adhesive layer is stacked on a covering film layer (hereinafter referred to as a "covering film side semi-finished product"). In addition, a semi-finished product in which a metal foil layer is stacked on a substrate film layer to form a desired circuit pattern (hereinafter referred to as a "substrate film side 2-layer semi-finished product") or a semi-finished product in which an adhesive layer is stacked on a substrate film layer and a metal foil layer is stacked thereon to form a desired circuit pattern (hereinafter referred to as a "substrate film side 3-layer semi-finished product") is manufactured (hereinafter, the substrate film side 2-layer semi-finished product and the substrate film side 3-layer semi-finished product are collectively referred to as the "substrate film side semi-finished product"). By laminating the semi-finished product on the cover film side and the semi-finished product on the base film side obtained in this way, a 4-layer or 5-layer printed wiring board can be obtained.

The substrate film-side semi-finished product can be obtained, for example, by a manufacturing method comprising the steps of (A) applying a resin solution to become a substrate film to the aforementioned metal foil and subjecting the coating to initial drying, and (B) heat treating and drying the laminate of the metal foil obtained in (A) and the initial dried coating (hereinafter referred to as "heat treatment-desolventizing step").

The circuit in the metal foil layer can be formed by a known method. An additive method or a subtractive method can be used. The subtractive method is preferred.

The obtained semi-finished product on the substrate film side can be directly used for bonding with the semi-finished product on the covering film side, or can be bonded with a release film and stored before being used for bonding with the semi-finished product on the covering film side.

The semi-finished product on the covering film side is manufactured, for example, by applying an adhesive to the covering film. A crosslinking reaction in the applied adhesive can be carried out as required. In an ideal implementation, the adhesive layer is semi-hardened.

The obtained semi-finished product on the covering film side can be directly used for bonding with the semi-finished product on the substrate film side, or can be bonded with a release film and stored before being used for bonding with the semi-finished product on the substrate film side.

The semi-finished product on the substrate film side and the semi-finished product on the cover film side are stored in the form of rolls, for example, and then bonded together to produce a printed wiring board. Any bonding method can be used, for example, pressing or rolling. Alternatively, the two can be bonded together while applying heat by heating pressing or using a heating roll device.

In the case of a soft and rollable reinforcing material such as a polyimide film, the semi-finished reinforcing material side is preferably manufactured by applying an adhesive to the reinforcing material. In the case of a hard and non-rollable reinforcing plate such as a metal plate such as SUS, aluminum, or a plate made by hardening glass fiber with epoxy resin, it is preferably manufactured by transferring and applying an adhesive that has been applied to a demolding substrate in advance. In addition, a crosslinking reaction in the applied adhesive can be carried out as needed. In an ideal implementation, the adhesive layer is semi-hardened.

The obtained semi-finished product on the side of the reinforcing material can be directly used for bonding with the back of the printed wiring board, or can be stored after bonding with a release film and then used for bonding with the semi-finished product on the side of the base film.

The semi-finished product on the substrate film side, the semi-finished product on the cover film side, and the semi-finished product on the reinforcing material side are all laminated bodies for printed wiring boards in the present invention.

<Example> The present invention is described in more detail below with reference to an example. However, the present invention is not limited to the example. In the example and comparative example, parts by mass are generally expressed in parts.

(Physical property evaluation method)

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

[Number average molecular weight (Mn)] The number average molecular weight in the present invention is a value measured using a gel permeation chromatograph manufactured by Shimadzu Corporation (hereinafter referred to as GPC, standard material: 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).

[Determination of Melting Point and Heat of Fusion] The melting point and heat of fusion in the present invention are measured by using a differential scanning calorimeter (hereinafter referred to as DSC, manufactured by TA Instruments Japan, Q-2000), heating and melting at a rate of 20°C/min, cooling and resinization, and then measuring the peak temperature and area of the melting peak when heating and melting again.

(1) Peel strength (adhesion) The adhesive composition described below was applied to a 12.5 μm thick polyimide film (manufactured by Kaneka Co., Ltd., APICAL (registered trademark)) to a thickness of 25 μm after drying, and dried at 130°C for 3 minutes. The adhesive film (B-grade product) prepared in this way was bonded to a 18 μm thick rolled copper foil (manufactured by JX Metal Co., Ltd., BHY series). The bonding was performed in such a way that the glossy surface of the rolled copper foil was in contact with the adhesive layer, and the bonding was performed by pressing at 160°C and a pressure of 40 kgf/ ^cm2 for 30 seconds. Then, the film was hardened by heat treatment at 140°C for 4 hours to obtain a sample for peel strength evaluation. The peel strength was measured by stretching the film at 25°C, performing a 90° peel test at a stretching speed of 50 mm/min, and measuring the peel strength. This test represents the adhesive strength at room temperature. In addition, samples were also prepared for liquid crystal polymer (LCP) film (BEXTOR CT-Z series, thickness 50 μm, manufactured by Curare Co., Ltd.) and parallel polystyrene (SPS) film (thickness 100 μm). <Evaluation criteria (PI film and LCP film)> ◎: 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 <Evaluation criteria (SPS film)> ◎: 0.7 N/mm or more ○: 0.5 N/mm or more and less than 0.7 N/mm △: 0.3 N/mm or more and less than 0.5 N/mm ×: less than 0.3 N/mm

(2) Solder heat resistance Samples were prepared in the same manner as above. Samples of 2.0 cm × 2.0 cm were aged at 23°C for 2 days and then floated in a solder bath melted at 280°C for 10 seconds to check for changes in appearance such as swelling. <Evaluation criteria> ◎: No swelling ○: Some swelling △: Many swellings ×: Swelling and discoloration

(3) Relative dielectric constant (ε _c ) and dielectric loss tangent (tanδ) The adhesive composition described below was applied to a Teflon (registered trademark) sheet having a thickness of 100 μm to a thickness of 25 μm after drying and curing, and dried at 130°C for 3 minutes. Then, after heat treatment at 140°C for 4 hours to cure, the Teflon (registered trademark) sheet was peeled off to obtain an adhesive resin sheet for testing. The sample was then cut into strips of 8 cm × 3 mm to obtain a test sample. The relative dielectric constant (ε _c ) and dielectric loss tangent (tanδ) were measured using a Network Analyzer (manufactured by Anritsu Corporation) by the cavity perturbation method at a temperature of 23°C and a frequency of 1 GHz. <Evaluation criteria for relative dielectric constant> ◎: 2.3 or less ○: more than 2.3 and less than 2.6 △: more than 2.6 and less than 3.0 ×: more than 3.0 <Evaluation criteria for dielectric loss tangent> ◎: 0.008 or less ○: more than 0.008 and less than 0.01 △: more than 0.01 and less than 0.02 ×: more than 0.02

(4) Pot life characteristics Pot life characteristics refer to the stability of the varnish immediately after or after a certain period of time after the resin solution (varnish) is prepared by mixing components (a) to (d) and a mixed solvent of methylcyclohexane and toluene (methylcyclohexane/toluene = 80/20 (v/v)) to a solid content concentration of 20 mass%. Good pot life characteristics refer to the stability of the varnish when the viscosity of the varnish increases little and can be stored for a long time. Poor pot life characteristics refer to the viscosity of the varnish increasing (thickening), which may cause gelation in severe cases, making it difficult to apply to the substrate and unable to be stored for a long time. The varnish prepared according to the ratio in Table 1 was measured for dispersion viscosity at 25°C using a Brookfield viscometer with a No. 2 spindle rotor and a rotation speed of 30 rpm to determine the initial dispersion viscosity ηB0. The varnish was then stored at 25°C for 7 days and the dispersion viscosity ηB was measured at 25°C. The varnish viscosity was calculated using the following formula and evaluated as follows. Solution viscosity ratio = solution viscosity ηB/solution viscosity ηB0 <Evaluation criteria> ◎: 0.5 or more and less than 1.5 ○: 1.5 or more and less than 2.0 △: 2.0 or more and less than 3.0 ×: 3.0 or more or the viscosity cannot be measured due to pudding

[Example 1] 80 parts by mass of acid-modified polyolefin CO-1, 20 parts by mass of polycyclic phenolic resin FTC-509, 10 parts by mass of epoxy resin HP-7200 and 440 parts by mass of organic solvent (methylcyclohexane/toluene = 80/20 (v/v)) (solid content concentration is 20% by mass) were mixed to obtain an adhesive composition. The mixing amount, bonding strength, solder heat resistance and electrical properties are shown in Table 1.

[Examples 2 to 18] The types and ratios of the resins used were changed as shown in Table 1, and Examples 2 to 18 were carried out in the same manner as Example 1. The bonding strength, solder heat resistance, electrical properties, and pot life properties are shown in Table 1. In addition, the organic solvent (methylcyclohexane/toluene = 80/20 (v/v)) was adjusted so that the solid content concentration was 20 mass %.

[Comparative Examples 1-4] The types and ratios of the resins used were changed as shown in Table 1, and Comparative Examples 1-4 were carried out in the same manner as Example 1. The bonding strength, solder heat resistance, electrical properties, and shelf life properties are shown in Table 1.

[Table 1] Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Embodiment Comparison Example Comparison Example Comparison Example Comparison Example 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 1 2 3 4 Acid-modified polyolefin (a) (wt.%) CO-1 80 80 80 95 70 50 80 80 80 80 80 80 80 80 80 100 80 80 CO-2 80 CO-3 80 CO-4 80 Phenolic resin (b) (wt.%) (b1)FTC509 20 20 20 20 5 30 50 20 20 20 20 20 20 20 20 20 20 100 (b2)FATC 20 (b3)FTC-809AE 20 (b4)T-100 20 Epoxy resin (c) (mass percentage) HP-7200 10 10 10 10 10 10 10 10 10 10 1 58 10 15 5 10 10 10 HP-7200H 10 jER-152 10 5 jER-630 10 Polycarbodiimide (d) (parts by weight) V-09GB 3 18 V-03 3 Adhesion strength (PI/Ad/Cu) Reviews ◎ ◎ ○ ○ ◎ ◎ ◎ ◎ ○ ◎ ◎ ◎ ◎ △ ◎ ◎ ◎ ◎ ◎ ◎ ○ × Solder heat resistance (PI/Ad/Cu) Reviews ○ ○ ○ ○ ◎ ○ △ ◎ ◎ ○ ○ ○ △ ○ ○ ○ ○ ◎ × ○ × ○ Adhesion strength (LCP/Ad/Cu) Reviews ◎ ◎ ○ ○ ◎ ◎ ◎ ◎ ○ ◎ ◎ ◎ ◎ △ ◎ ◎ ◎ ◎ ◎ ◎ ○ × Solder heat resistance (LCP/Ad/Cu) Reviews ○ ○ ○ ○ ◎ ○ △ ◎ ◎ ○ ○ ○ △ ○ ○ ○ ○ ○ × ○ × ○ Adhesion strength (SPS/Ad/Cu) Reviews ○ ○ ○ ○ ○ ○ ○ ◎ ○ ◎ ○ ○ ○ △ ◎ ◎ ○ ◎ ◎ ◎ ○ × Solder heat resistance (SPS/Ad/Cu) Reviews ○ ○ ○ ○ ◎ ○ △ ◎ ◎ ○ ○ ○ △ ○ ○ ○ ○ ○ × ○ × ○ Electrical properties Relative dielectric constant ◎ ◎ ◎ ◎ ◎ ◎ ◎ ○ ○ ◎ ◎ ◎ ◎ △ ◎ ○ ◎ ◎ ◎ × ◎ × Dielectric loss tangent ◎ ◎ ◎ ◎ ◎ ◎ ◎ ○ △ ◎ ◎ ◎ ◎ △ ◎ ○ ◎ ◎ ◎ × ◎ ○ Applicable period characteristics initial ○ ◎ ◎ ◎ ○ ○ ◎ ○ ○ ○ ○ ○ ◎ △ ○ ○ ○ ○ ◎ ◎ ◎ ◎ 25℃×1 week later ○ ○ ○ ◎ ○ ○ ○ ○ ○ ○ ○ ○ ◎ △ ○ ○ ○ ○ ◎ ○ ◎ ◎

The acid-modified polyolefin (a), phenolic resin having a polycyclic structure (b), epoxy resin (c), and polycarbodiimide (d) used in Table 1 are as follows. (Phenolic resin having a polycyclic structure (b)) Phenolic resin (b1): FTC-509 (manufactured by Qunrong Chemical Industry Co., Ltd.), a phenolic resin having the structure of the general formula (2) and the general formula (11). Both x and y are 0, _Z1 is 1, and the hydroxyl group is bonded to the para position of the benzyl group. Phenolic resin (b2): FATC-809 (manufactured by Qunrong Chemical Industry Co., Ltd.), a phenolic resin having the structure of the general formula (2) and the general formula (11). R ₃ and R ₄ are both 2-propenyl, x, y, and Z ₁ are all 1, and the hydroxyl group is bonded to the para position of the benzyl group. Phenolic resin (b3): FTC-809AE (manufactured by Qunrong Chemical Industry Co., Ltd.), a phenolic resin having the structure of general formula (2) and general formula (12). x and y are both 0, Z ₁ and Z ₂ are both 1, and the ether group is bonded to the para position of the benzyl group. Phenolic resin (b4): YS POLYSTAR T-100 (phenolic resin without polycyclic structure manufactured by Yasuhara Chemical) (Epoxy resin (c)) Dicyclopentadiene epoxy resin: HP-7200 (manufactured by DIC Corporation, epoxy equivalent 259 g/eq) Dicyclopentadiene epoxy resin: HP-7200H (manufactured by DIC Corporation, epoxy equivalent 278 g/eq) Cresol novolac epoxy resin: jER-152 (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 177 g/eq) Triglycidyl para-aminophenol: jER-630 (manufactured by Mitsubishi Chemical Corporation, epoxy equivalent 98 g/eq) (Polycarbodiimide (d)) Carbodiimide resin: V-09GB (manufactured by Nisshinbo Chemical Co., Ltd., carbodiimide equivalent 216g/eq) Carbodiimide resin: V-03 (manufactured by Nisshinbo Chemical Co., Ltd., carbodiimide equivalent 209g/eq)

(Acid-modified polyolefin (a)) [Production Example 1] In a 1L high temperature and high pressure autoclave, 100 parts by mass of propylene-butene copolymer ("TAFMER (registered trademark) XM7080" manufactured by Mitsui Chemicals Co., Ltd.), 150 parts by mass of toluene, 19 parts by mass of maleic anhydride, and 6 parts by mass of di-(tertiary)butyl peroxide were added, and the temperature was raised to 140°C, and then stirred for 3 hours. Thereafter, the obtained reaction solution was cooled and poured into a container containing a large amount of methyl ethyl ketone to precipitate the resin. Thereafter, by centrifuging the liquid containing the resin, the acid-modified propylene-butene copolymer grafted with maleic anhydride, (poly)maleic anhydride, and low molecular weight substances were separated and purified. Thereafter, by drying at 70°C for 5 hours under reduced pressure, 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) was obtained.

[Production Example 2] The same procedure as in Production Example 1 was followed except that the amount of maleic anhydride fed was changed to 14 parts by mass, thereby obtaining 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).

[Production Example 3] The same procedure as in Production Example 1 was followed except that the amount of maleic anhydride fed was changed to 11 parts by mass, thereby obtaining 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).

[Production Example 4] The same procedure as in Production Example 1 was followed except that the amount of maleic anhydride fed was changed to 6 parts by mass, thereby obtaining a maleic anhydride-modified propylene-butene copolymer (CO-4, acid value 7 mgKOH/g, number average molecular weight 35,000, Tm 82°C, ΔH 25 J/g).

As can be seen from Table 1, in Examples 1 to 18, the main agent has excellent usable life characteristics. As for the adhesive, it has excellent adhesion to resin substrates (PI, LCP, SPS) and copper foil, solder heat resistance, and low dielectric properties. In contrast, in Comparative Example 1, component (b) is not mixed, so the solder heat resistance is poor. In Comparative Example 2, component (b) does not have a polycyclic structure, so the low dielectric properties (electrical properties) are poor. In Comparative Example 3, component (c) is not contained, so the solder heat resistance is poor. In Comparative Example 4, component (a) is not mixed, so the bonding strength with each substrate is poor and the low dielectric properties are poor. [Industrial Utilization]

The adhesive composition of the present invention has high adhesion not only to the known polyimide and polyethylene terephthalate films, but also to resin substrates such as LCP and SPS, and metal substrates such as copper foil, and can obtain high solder heat resistance, and is also excellent in shelf life characteristics and low dielectric properties (electrical properties). The adhesive composition of the present invention can obtain an adhesive sheet and a laminate formed by bonding the adhesive sheet. Due to the above characteristics, it is effective in the use of flexible printed wiring boards, especially in FPC uses that require low dielectric properties (low dielectric constant, low dielectric loss tangent) in the high-frequency region.

Claims (10)

An adhesive composition comprises: an acid-modified polyolefin (a), a phenolic resin (b) having a polycyclic structure, and an epoxy resin (c), wherein the phenolic resin (b) having a polycyclic structure is a phenolic resin having a tricyclic decane skeleton. As in the adhesive composition of claim 1, the phenolic resin (b) having a polycyclic structure is a phenolic resin having a carbonate skeleton. In the adhesive composition of claim 1 or 2, the acid value of the acid-modified polyolefin (a) is 5-40 mgKOH/g. The adhesive composition of claim 1 or 2 further contains polycarbodiimide (d). The adhesive composition of claim 1 or 2, wherein, relative to 100 parts by weight of the acid-modified polyolefin (a), it contains 0.05 to 120 parts by weight of a phenolic resin (b) having a polycyclic structure and 0.1 to 60 parts by weight of an epoxy resin (c). The adhesive composition of claim 4, wherein the polycarbodiimide (d) is contained in an amount of 0.1 to 30 parts by weight relative to 100 parts by weight of the acid-modified polyolefin (a). The adhesive composition of claim 1 or 2 has a relative dielectric constant (ε _c ) of less than 3.0 and a dielectric loss tangent (tan δ) of less than 0.02 at 1 GHz. An adhesive sheet containing an adhesive composition as described in any one of claims 1 to 7. A laminate containing an adhesive composition as described in any one of claims 1 to 7. A printed wiring board comprises the laminate as claimed in claim 9 as a constituent element.