CN112218929A

CN112218929A - Adhesive composition using resin having imide bond and phosphorus compound

Info

Publication number: CN112218929A
Application number: CN201980036484.6A
Authority: CN
Inventors: 小柳英之; 川楠哲生
Original assignee: Toyobo Co Ltd
Current assignee: Toyobo Co Ltd
Priority date: 2018-10-04
Filing date: 2019-10-01
Publication date: 2021-01-12
Also published as: WO2020071364A1; TW202022006A; KR20210070951A; JPWO2020071364A1

Abstract

The invention provides an adhesive composition which has excellent adhesiveness, heat resistance, operability and insulation reliability and is suitable for an adhesive film, a cover film, a copper-clad laminated plate and the like. An adhesive composition characterized by containing a resin having an imide bond and a phosphorus compound having a specific structure.

Description

Adhesive composition using resin having imide bond and phosphorus compound

Technical Field

The present invention relates to an adhesive composition using a resin having an imide bond and a phosphorus compound, and an adhesive film, a coverlay film, a copper-clad laminate, and a flexible printed wiring board using the adhesive composition.

Background

Flexible printed wiring boards are widely used as electronic equipment components requiring flexibility and space saving, for example, device substrates for display devices such as liquid crystal displays and plasma displays, substrate relay cables for cellular phones, digital cameras, portable game machines, and the like, and operation switch substrates, and are expected to expand the range of applications.

Adhesives used for flexible printed wiring boards are used in the parts constituting flexible wiring boards such as adhesive films, coverlay films, and copper-clad laminates, and are required to have adhesiveness, heat resistance, flame retardancy, and insulation reliability.

With recent electronic devices being light, thin and small, the density of wiring in flexible printed wiring boards has been increasing. Further, to achieve higher density of wiring, the space width between circuits needs to be reduced, and an adhesive used for a flexible printed wiring board is required to further improve insulation reliability.

Epoxy resins, acrylic resins, urethane resins, and the like are currently used as adhesives for flexible printed wiring boards, and have insufficient heat resistance in response to recent increase in wiring density and lead-free solder, and polyimide resins have been studied as adhesives having heat resistance in place of these resins.

In addition, a method of mixing a phosphorus compound containing no halogen element such as bromine is widely used for imparting flame retardancy to an adhesive used for a flexible printed wiring board. Among them, phosphonic acid derivatives having a chemical structure represented by general formula (4) (generally referred to as DOP) are widely used from the viewpoint of heat resistance, flame retardancy, or compatibility.

[ chemical formula 4]

Specific examples of the phosphonic acid derivative include a method using: 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide represented by chemical formula (5), 9, 10-dihydro-10-benzyl-9-oxa-10-phosphaphenanthrene-10-oxide represented by chemical formula (6), 10- (2, 5-dihydroxybenzene) -10H-9-oxa-10-phosphaphenanthrene-10-oxide represented by chemical formula (6), and the like (for example, see patent documents 1 and 2).

[ chemical formula 5]

[ chemical formula 6]

[ chemical formula 7]

Documents of the prior art

Patent document

Patent document 1: japanese patent No. 5278785

Patent document 2: japanese patent laid-open publication No. 2011-148862

Disclosure of Invention

Problems to be solved by the invention

However, the 9, 10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide represented by the chemical formula (5) has a low molecular weight, and thus has a low thermal weight loss temperature, and when a part thereof remains uncured, there is a technical problem of low heat resistance. In addition, 9, 10-dihydro-10-benzyl-9-oxa-10-phosphaphenanthrene-10-oxide represented by chemical formula (6) has a small molecular weight and a large plasticizing effect, and thus easily bleeds out under a high-temperature and high-humidity environment, resulting in a technical problem of low insulation reliability. Further, 10- (2, 5-dihydroxyphenyl) -10H-9-oxa-10-phosphaphenanthrene-10-oxide represented by the chemical formula (7) has a low solubility in a solvent, and thus has a technical problem of low operability.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an adhesive composition having excellent adhesiveness, heat resistance, flame retardancy, and workability, and further having high insulation reliability.

Technical scheme for solving problems

The present inventors have conducted intensive studies to achieve the above object, and as a result, have completed the present invention by using a resin having an imide bond and a specific phosphorus compound in combination.

That is, the present invention includes the following configurations.

An adhesive composition characterized by comprising: a resin having an imide bond and a phosphorus compound represented by the general formula (1).

[ chemical formula 1]

(in the general formula (1), n is an integer of 2 to 6, and each of X is independently CH₂Or O).

The phosphorus compound represented by the general formula (1) is preferably a phosphorus compound represented by the general formula (2) and/or a phosphorus compound represented by the general formula (3).

[ chemical formula 2]

(in the general formula (2), X is CH₂Or O).

[ chemical formula 3]

(in the general formula (3), X is CH₂Or O).

The resin having an imide bond is preferably a polyimide resin, a polyamideimide resin, a polyetherimide resin, a polyetheretherketone resin, a polyesterimide resin, or a polycarbonate imide resin. Further, the copolymer component of the resin having an imide bond preferably contains trimellitic anhydride or acrylonitrile butadiene rubber modified with carboxyl groups at both ends.

Further preferably, the epoxy resin is contained, and the epoxy resin is preferably liquid at 25 ℃ and has 2 or more epoxy groups in 1 molecule.

The adhesive composition according to any of the above items, wherein the adhesive composition is used for printed wiring boards. An adhesive film characterized by using the adhesive composition. A coverlay film or a copper-clad laminate using the adhesive film. A flexible printed wiring board is characterized in that the coverlay film or the copper-clad laminate is used.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, by using a combination of a resin having an imide bond and a specific phosphorus compound, an adhesive composition having excellent adhesion, heat resistance, flame retardancy, and workability, and further excellent high insulation reliability, and an adhesive film, a coverlay film, a copper-clad laminate, and a flexible printed wiring board using the same can be obtained.

Detailed Description

< resin having imide bond >

The resin having an imide bond used in the adhesive composition of the present invention has 1 or more imide bonds in a repeating unit of the resin, and examples thereof include: polyimide resins, polyamide-imide resins, polyether-ether-ketone resins, polyester-imide resins, polycarbonate-imide resins, and the like. It is preferable to have 2 or more imide bonds in the repeating unit of the resin. The resin having an imide bond is preferably a resin containing an acid component and a diisocyanate component or a diamine component as a copolymerization component. Hereinafter, the diisocyanate component or the diamine component is collectively referred to as an amine component. The acid component may be any of an acid component having an aromatic ring (aromatic acid component), an aliphatic acid component, or an alicyclic acid component, and is preferably a polycarboxylic acid component having an aromatic ring. The amine component (diisocyanate component or diamine component) may be any of an amine component having an aromatic ring, an aliphatic amine component, or an alicyclic amine component, and is preferably an amine component having an aromatic ring. That is, it is preferable that the structural unit contains a structural unit derived from a polycarboxylic acid component having an aromatic ring and a structural unit derived from a diisocyanate component having an aromatic ring or a diamine component having an aromatic ring.

The resin having an imide bond used in the adhesive composition of the present invention preferably has a carboxyl group or an acid anhydride group as a reactive functional group. The acid value of the resin having an imide bond is preferably 5mgKOH/g or more, more preferably 10mgKOH/g or more, and still more preferably 20mgKOH/g or more. Further, it is preferably not more than 150mgKOH/g, more preferably not more than 120mgKOH/g, and still more preferably not more than 100 mgKOH/g. When the amount is within the above range, the crosslinking points of the epoxy resin and the curing agent increase, the crosslinking density of the coating film after heat curing increases, and the heat resistance improves.

As the acid component of the resin having an imide bond of the present invention, a polycarboxylic acid component having an aromatic ring is preferably used. As the polycarboxylic acid component having an aromatic ring, an acid anhydride of a polycarboxylic acid having an aromatic ring is preferable, and specifically, trimellitic anhydride (TMA) is more preferably used. By using trimellitic anhydride, an amide bond is formed in addition to an imide bond, and the solvent solubility of the resin can be improved. When the total acid content is 100 mol%, trimellitic anhydride is preferably 30 mol% or more, more preferably 40 mol% or more, and still more preferably 50 mol% or more. The upper limit is not limited, and may be 100 mol%, preferably 90 mol% or less, more preferably 80 mol% or less, and still more preferably 70 mol% or less.

Examples of the polycarboxylic acid component having an aromatic ring other than trimellitic anhydride include: alkyl diol bistrimellitic anhydrides such as pyromellitic dianhydride (PMDA), 3 ', 4, 4' -Benzophenone Tetracarboxylic Dianhydride (BTDA), 3 ', 4, 4' -biphenyl tetracarboxylic dianhydride (BPDA), ethylene glycol bistrimellitic anhydride (TMEG), propylene glycol bistrimellitic anhydride, 1, 4-butanediol bistrimellitic anhydride, hexamethylene bistrimellitic anhydride, polyethylene glycol bistrimellitic anhydride, and polypropylene glycol bistrimellitic anhydride; 1,2, 5, 6-naphthalenetetracarboxylic dianhydride, 1,4, 5, 8-naphthalenetetracarboxylic dianhydride, 2,3,5, 6-pyridinetetracarboxylic dianhydride, 3,4, 9, 10-perylenetetracarboxylic dianhydride, 3, 3 ', 4, 4 ' -diphenylsulfonetetracarboxylic dianhydride, 4, 4 ' -oxydiphthalic anhydride, 1, 1, 1,3, 3, 3-hexafluoro-2, 2-bis (2, 3-or 3, 4-dicarboxyphenyl) propane dianhydride, 2-bis [4- (2, 3-or 3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, 1, 1, 1,3, 3, 3-hexafluoro-2, 2-bis [4- (2, 3-or 3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride, 1, 3-bis (3, 4-dicarboxyphenyl) -1, 1,3, 3-tetramethyldisiloxane dianhydride, and the like. These may be used alone or in combination of two or more.

As the other acid component, an aliphatic or alicyclic acid anhydride or an aromatic, aliphatic or alicyclic dicarboxylic acid can be used. For example, any of the components listed above may be used as the material obtained by hydrogenation. Specific examples thereof include: 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 2-cyclohexanedicarboxylic acid, meso-butane-1, 2,3, 4-tetracarboxylic dianhydride, pentane-1, 2,4, 5-tetracarboxylic dianhydride, cyclobutanetetracarboxylic dianhydride, cyclopentane-tetracarboxylic dianhydride, cyclohexyl-1-ene-2, 3,5, 6-tetracarboxylic dianhydride, 3-ethylcyclohexyl-1-ene-3- (1, 2), 5, 6-tetracarboxylic dianhydride, 1-methyl-3-ethylcyclohexane-1-ene-3- (1, 2), 5, 6-tetracarboxylic dianhydride, 1-ethylcyclohexane-1- (1, 2), 3, 4-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2, 3), 3, 4-tetracarboxylic dianhydride, 1, 3-dipropylcyclohexane-1- (2, 3), 3- (2, 3) -tetracarboxylic dianhydride, dicyclohexyl-3, 4,3 ', 4' -tetracarboxylic dianhydride, bicyclo [2.2.1] heptane-2, 3,5, 6-tetracarboxylic dianhydride, 1-propylcyclohexane-1- (2, 3), 3, 4-tetracarboxylic dianhydride, 1, 3-dipropylcyclohexane-1- (2, 3), 3- (2, 3) -tetracarboxylic dianhydride, dicyclohexyl-3, 4,3 ', 4' -tetracarboxylic dianhydride, bicyclo [2.2.1] heptane-2, 3,5, 6-tetracarboxylic dianhydride, bicyclo [2.2.2] octane-7-ene-2, 3,5, 6-tetracarboxylic dianhydride, cyclohexanedicarboxylic acid, and the like. Examples of the aromatic diacid include: terephthalic acid, isophthalic acid, phthalic acid, naphthalenedicarboxylic acid, diphenyletherdicarboxylic acid, stilbenedicarboxylic acid, and the like. Examples of the aliphatic dicarboxylic acid include: succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, eicosanedioic acid, 2-methylsuccinic acid, 2-methyladipic acid, 3-methylpentanedicarboxylic acid, 2-methyloctane dicarboxylic acid, 3, 8-dimethyldecane dicarboxylic acid, 3, 7-dimethyldecane dicarboxylic acid, 9, 12-dimethyleicosanedioic acid, fumaric acid, maleic acid, and the like. These may be used singly or in combination of a plurality of kinds. In view of heat resistance, adhesion, solubility, cost, and the like, sebacic acid, 1, 4-cyclohexanedicarboxylic acid, or isophthalic acid is preferable, and sebacic acid is more preferable. When these components are used, the total acid content is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more, based on 100 mol% of the resin having an imide bond to be obtained, from the viewpoint of heat resistance and flame retardancy. Further, it is preferably 60 mol% or less, more preferably 50 mol% or less, and still more preferably 45 mol% or less.

As the amine component (diisocyanate component or diamine component) used in the present invention, an amine component (aromatic diisocyanate or aromatic diamine) having an aromatic ring is preferable. Examples of the diisocyanate having an aromatic ring include diphenylmethane-2, 4 ' -diisocyanate, diphenylmethane-4, 4 ' -diisocyanate, 3, 2 ' -or 3, 3 ' -or 4, 2 ' -or 4,3 ' -or 5, 2 ' -or 5, 3 ' -or 6, 2 ' -or 6, 3 ' -dimethyldiphenylmethane-2, 4 ' -diisocyanate, 3, 2 ' -or 3, 3 ' -or 4, 2 ' -or 4,3 ' -or 5, 2 ' -or 5, 3 ' -or 6, 2 ' -or 6, 3 ' -diethyldiphenylmethane-2, 4 ' -diisocyanate, 3, 2 ' -or 3, 3 ' -or 4, 2 ' -or 4,3 '-or 5, 2' -or 5, 3 '-or 6, 2' -or 6, 3 '-dimethoxydiphenylmethane-2, 4' -diisocyanate, diphenylmethane-3, 3 '-diisocyanate, diphenylmethane-3, 4' -diisocyanate, diphenyl ether-4, 4 '-diisocyanate, benzophenone-4, 4' -diisocyanate, diphenylsulfone-4, 4 '-diisocyanate, toluene-2, 4-diisocyanate, toluene-2, 6-diisocyanate, m-xylylene diisocyanate, p-xylylene diisocyanate, naphthalene-2, 6-diisocyanate, 4' - [2, 2 bis (4-phenoxyphenyl) propane ] diisocyanate, mixtures thereof, and mixtures thereof, 3, 3 '-or 2, 2' -dimethylbiphenyl-4, 4 '-diisocyanate, 3' -or 2, 2 '-diethylbiphenyl-4, 4' -diisocyanate, 3 '-dimethoxybiphenyl-4, 4' -diisocyanate, 3 '-diethoxybiphenyl-4, 4' -diisocyanate, and the like. The diamine component having an aromatic ring includes diamines corresponding to these diisocyanates. These may be used alone or in combination of two or more. Among them, diphenylmethane-4, 4' -diisocyanate is preferable.

The amine component having an aromatic ring is preferably 80 mol% or more, more preferably 90 mol% or more, further preferably 95 mol% or more, and may be 100 mol% when the total amine component is 100 mol%. By setting the content within the above range, a resin having an imide bond excellent in adhesiveness and heat resistance can be obtained. As the amine component, a diisocyanate component having an aromatic ring may be used alone, or a diamine component having an aromatic ring may be used alone, or each of them may be used in combination. Among them, diisocyanate components having aromatic rings are preferably used alone.

As the other amine component, an aliphatic amine component (aliphatic diisocyanate or aliphatic diamine) or an alicyclic amine component (alicyclic diisocyanate or alicyclic diamine) may be used insofar as the effect of the present invention is not impaired. For example, a diisocyanate or diamine obtained by hydrogenating any of the above-listed components can be used. Specific examples thereof include isophorone diisocyanate, 1, 4-cyclohexane diisocyanate, 1, 3-cyclohexane diisocyanate, 4, 4' -dicyclohexylmethane diisocyanate, ethylene diisocyanate, propylene diisocyanate, hexamethylene diisocyanate, and diamines thereof. These may be used alone or in combination of two or more. From the viewpoint of heat resistance and flame retardancy of the resulting resin having an imide bond, the content of these components is preferably 20 mol% or less, more preferably 10 mol% or less, even more preferably 5 mol% or less, and may be 0 mol% when the total amine content is 100 mol%.

The resin having an imide bond of the present invention may be copolymerized with a compound having 3 or more functional groups for the purpose of increasing the reaction point with the epoxy resin and improving the heat resistance of the obtained adhesive composition, within a range not impairing the effects of the present invention. For example, polyfunctional carboxylic acids such as trimesic acid, and dicarboxylic acids having a hydroxyl group such as 5-hydroxyisophthalic acid; dicarboxylic acids having an amino group such as 5-aminoisophthalic acid; substances having 3 or more hydroxyl groups such as glycerin and polyglycerin; tris (2-aminoethyl) amine and the like having 3 or more amino groups. Among them, polyfunctional carboxylic acids such as trimesic acid are preferable from the viewpoint of heat resistance, and the amount thereof is preferably 10 mol% or less, more preferably 5 mol% or less, when the total acid components are 100 mol%. If the amount is more than 10 mol%, gelation may occur during polymerization or insoluble matter may be formed.

The resin having an imide bond of the present invention may be obtained by copolymerizing, as components for imparting flexibility and adhesiveness, the following soft components: two-terminal carboxyl-modified acrylonitrile butadiene rubber, polyester diol, polyether diol, polycarbonate diol, dimer acid, hydrogenated dimer acid, dimer acid diol, two-terminal carboxyl-modified polysiloxane, two-terminal anhydride-modified polysiloxane, two-terminal carboxyl-modified polybutadiene, two-terminal carboxyl-modified hydrogenated polybutadiene, polybutadiene diol, hydrogenated polybutadiene diol, and the like. Of these, acrylonitrile butadiene rubber modified with carboxyl groups at both ends is preferable from the viewpoint of flexibility and adhesiveness. When these soft components are used, the total amount of the resin solid components is preferably 10% by mass or more, more preferably 20% by mass or more, based on 100% by mass of the total resin solid components. Further, it is preferably 60% by mass or less, and more preferably 50% by mass or less. By having the above range, flexibility can be imparted to the resin without impairing the effects of adhesiveness, heat resistance, and flame retardancy.

The resin having an imide bond of the present invention can be produced by the following method: a method for producing an acid component and a diisocyanate component (isocyanate method); or a method in which an acid component is reacted with a diamine component to form an amic acid, followed by ring closure (direct method); or a method of reacting a compound having an acid anhydride and an acid chloride with a diamine (acid chloride method). Industrially, the isocyanate method is advantageous.

In the following, a typical isocyanate method is described for the method for producing a resin having an imide bond, but a resin having an imide bond can be produced similarly by the above-described direct method and the acid chloride method using the corresponding amine and acid/acid chloride, respectively.

The polymerization reaction of the resin having an imide bond of the present invention can be carried out by heating the acid component and the diisocyanate component in a solvent to 60 to 200 ℃ and stirring them, as conventionally known. In this case, the molar ratio of the acid component to the diisocyanate component is preferably in the range of 85/100 to 100/100. The contents of the acid component and the diisocyanate component in the resin having an imide bond are generally the same as the ratio of the respective components at the time of polymerization. In addition, in order to promote the reaction, alkali metals such as sodium fluoride, potassium fluoride, sodium methoxide; amines such as triethylenediamine, triethylamine, 1, 8-diazabicyclo [ 5.4.0 ] -7-undecene, 1, 5-diazabicyclo [ 4.3.0 ] -5-nonene, and catalysts such as dibutyltin dilaurate. Since the catalyst effect cannot be obtained when the amount of the catalyst is too small and the side reaction may be caused when the amount of the catalyst is too large, the amount of the catalyst is preferably 0.01 to 5 mol%, more preferably 0.1 to 3 mol% based on 100 mol% of the acid component or the isocyanate component.

The resin having an imide bond preferably has a molecular weight corresponding to a logarithmic viscosity of 0.1 to 0.8(dl/g) at 30 ℃, more preferably has a molecular weight corresponding to a logarithmic viscosity of 0.2 to 0.7(dl/g), and still more preferably has a molecular weight corresponding to a logarithmic viscosity of 0.25 to 0.65 (dl/g). When the amount is within the above range, excellent adhesiveness and heat resistance can be obtained.

The glass transition temperature of the resin having an imide bond is preferably 80 ℃ or higher, more preferably 100 ℃ or higher, and still more preferably 120 ℃ or higher. The upper limit is not particularly limited, but is preferably 300 ℃ or lower, more preferably 290 ℃ or lower, and still more preferably 285 ℃ or lower. When the amount is within the above range, excellent adhesiveness and heat resistance can be obtained.

As the solvent used for polymerization of the resin having an imide bond of the present invention, for example, there can be mentioned: n-methyl-2-pyrrolidone, γ -butyrolactone, dimethylimidazolidinone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, cyclohexanone, cyclopentanone, and the like, and among them, dimethylacetamide is preferable because of its low boiling point and good polymerization efficiency. After the polymerization, the concentration of the nonvolatile component and the solution viscosity can be adjusted by diluting with a solvent used for the polymerization or another low boiling point solvent.

As the low boiling point solvent, there can be mentioned: aromatic solvents such as toluene and xylene; aliphatic solvents such as hexane, heptane and octane; alcohol solvents such as methanol, ethanol, propanol, butanol, and isopropanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and cyclopentanone; ether solvents such as diethyl ether and tetrahydrofuran; and ester solvents such as ethyl acetate, butyl acetate, and isobutyl acetate.

The content of the resin having an imide bond in the nonvolatile component of the adhesive composition of the present invention is preferably 40% by mass or more, more preferably 45% by mass or more, and still more preferably 50% by mass or more. Further, it is preferably 90% by mass or less, more preferably 80% by mass or less, and further preferably 70% by mass or less. When the content is within the above range, the adhesive composition can exhibit excellent adhesiveness and heat resistance.

< phosphorus Compound represented by the general formula (1) >

Bonding of the inventionThe agent composition contains a phosphorus compound represented by the general formula (1) (hereinafter, also referred to as a phosphorus compound of the general formula (1)). By containing the phosphorus compound of the general formula (1), an adhesive composition having excellent adhesiveness, heat resistance, flame retardancy and insulation reliability can be obtained. In the general formula (1), n is an integer of 2 to 6, preferably an integer of 2 to 5, more preferably an integer of 2 to 4, further preferably 2 or 3, and particularly preferably 2. When n is 2, the position of the substituent is not particularly limited, and may be any of the 1, 2-position (ortho position), the 1, 3-position (meta position), or the 1, 4-position (para position), and is preferably the 1, 3-position (meta position) or the 1, 4-position (para position). When n is 3, the position of the substituent is not particularly limited, and may be any of the 1,2,3, 1,2,4 or 1,3,5 positions, and when n is 4, the position of the substituent is not particularly limited, and may be any of the 1,2,3,4, 1,2,3,5 or 1,2,4,5 positions. Among them, n is preferably 2, and the position of the substituent is 1,3 (meta) or 1,4 (para). Each X is independently a-CH₂- (-) is a site directly bonded to the aromatic ring and the phosphorus atom of the general formula (1) and hereinafter, simply referred to as CH₂Or O). Preferably, at least one of the plurality of xs is O, more preferably 2 or more, still more preferably 3 or more, and particularly preferably all xs are O. The phosphorus compound of the general formula (1) may be a single compound or a mixture of a plurality of compounds having different substituents. Since the phosphorus compound of the general formula (1) has a large molecular weight and a small plasticizing effect, bleeding does not occur in a high-temperature and high-humidity environment, and excellent insulation reliability can be exhibited.

The content of the phosphorus compound of the general formula (1) is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, further preferably 15 parts by mass or more, and particularly preferably 20 parts by mass or more, per 100 parts by mass of the resin having an imide bond. Further, it is preferably 100 parts by mass or less, more preferably 90 parts by mass or less, further preferably 80 parts by mass or less, and particularly preferably 70 parts by mass or less. By setting the above range, excellent adhesion, heat resistance, flame retardancy and insulation reliability can be exhibited.

As the phosphorus compound of the general formula (1), a phosphorus compound having a structure represented by chemical formula (8) and/or chemical formula (9) (hereinafter, also referred to as a phosphorus compound of chemical formula (8) and a phosphorus compound of chemical formula (9), respectively) is preferable. The ratio of the total amount of the phosphorus compounds of chemical formula (8) and/or chemical formula (9) in the phosphorus compound of general formula (1) is preferably 30% by mass or more, more preferably 50% by mass or more, further preferably 80% by mass or more, particularly preferably 90% by mass or more, and may be 100% by mass. By containing the components in the above ratio, excellent insulation reliability can be exhibited.

[ chemical formula 8]

[ chemical formula 9]

The phosphorus compound of the general formula (1) has high solubility in a solvent, and therefore, the workability after preparation of the adhesive composition is good. Examples of the solvent include: n-methyl-2-pyrrolidone, γ -butyrolactone, dimethyl imidazolidinone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, cyclohexanone, cyclopentanone, and the like. Further, as the low boiling point solvent, there can be mentioned: aromatic solvents such as toluene and xylene; aliphatic solvents such as hexane, heptane and octane; alcohol solvents such as methanol, ethanol, propanol, butanol, and isopropanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and cyclopentanone; ether solvents such as diethyl ether and tetrahydrofuran; and ester solvents such as ethyl acetate, butyl acetate, and isobutyl acetate. The phosphorus compound of the general formula (1) is dissolved in the solvent at room temperature (25 ℃) preferably at least 10 mass%, more preferably at least 20 mass%.

Phosphorus compounds other than the phosphorus compound of the general formula (1) may be added within a range not impairing the effects of the present invention. For example, phosphonic Acid derivatives such as BCA, HCA (registered trademark), BzHCA, M-Acid, M-Ester, HCA-HQ, HCA-NQ and the like, which are trade names produced by Kagaku (Kagaku Co., Ltd.), condensed phosphate compounds such as CR-733S, CR-741, PX-200, PX-202, ADEKA (registered trademark) STAB-600 and PFR, which are trade names produced by Kagaku (Kagaku Co., Ltd.), cyclic phosphazenes such as SPB-100, SPE-100 and SPB-100L, SPH-100, FP-110, FP-300, FP-400, FP-430, FP-500, FP-800-H, FP-539900-1000 and the like, which are trade names produced by Kagaku (Kagaku Co., Ltd.), examples of the flame retardant include a phosphorus aluminum salt compound such as Exolit (registered trademark) OP series manufactured by Clariant Japan, a melamine compound such as PHOSMEL (registered trademark) 200 manufactured by Nissan chemical corporation, and an intumescent flame retardant such as ADEKA STAB FP-2100JC and FP-2200S, FP-2500S manufactured by ADEKA, and these may be used alone or in combination of two or more.

The preferable phosphorus content of the nonvolatile component in the adhesive composition of the present invention is 1.0 to 5.0 mass%, and more preferably 1.0 to 3.0 mass%. When the phosphorus content is small, good flame retardancy cannot be obtained, while when it is large, adhesiveness, heat resistance and insulation reliability tend to be lowered.

The flame retardant containing no phosphorus may be added within a range not impairing the effects of the present invention. For example, there may be mentioned: aluminum hydroxide such as Hijilite (registered trademark) H-42, H-42M, H-43, H-43M manufactured by Showa Denko K.K., magnesium hydroxide such as KISUMA (registered trademark) 5, 8, 5Q-S, 200-06H manufactured by Kagaku K.K., and melamine cyanurate compounds such as MC-4000, MC-4500, MC-6000 manufactured by Nissan chemical Co., Ltd., can be used alone or in combination of two or more.

The adhesive composition of the present invention may be mixed with an epoxy resin. The content of the epoxy resin is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, and further preferably 25 parts by mass or more, per 100 parts by mass of the resin having an imide bond. Further, it is preferably 100 parts by mass or less, more preferably 80 parts by mass or less, and further preferably 70 parts by mass or less. By setting the content of the imide bond-containing resin to the upper limit or less, the content of the imide bond-containing resin can be maintained at a certain level or more. Therefore, the epoxy resin does not remain uncured, and the heat resistance of the adhesive composition after curing is good. When the content is not less than the lower limit, a sufficient crosslinking reaction with the resin having an imide bond can be formed, and the adhesive composition after curing has good heat resistance and insulation reliability.

The epoxy resin used in the adhesive composition of the present invention may be in any of a liquid, semi-solid, or solid state at 25 ℃, and is preferably a liquid state at 25 ℃, and is an epoxy resin having 2 or more epoxy groups in 1 molecule. The epoxy resin may be modified, and may contain a sulfur atom, a nitrogen atom, a phosphorus atom, or the like in the molecular skeleton. For example, there may be mentioned: bisphenol a-type epoxy resin, bisphenol F-type epoxy resin, or hydrogenated products thereof, novolac-type (Phenolic novolac) epoxy resin, naphthalene-type epoxy resin, dicyclopentadiene-type epoxy resin, NBR (acrylonitrile butadiene rubber modified with carboxyl groups at both ends) modified epoxy resin, dimer acid-modified epoxy resin, polybutadiene-modified epoxy resin, aliphatic epoxy resin, alicyclic epoxy resin, and the like. As commercial products of these, for example, there are listed: trade names of jER (registered trademark) 825, jER827, jER828, YL980, and DIC (registered trademark) EPICLON (registered trademark) 840, 840-S, 850-S, EXA-850CRP, 850-LC, and the trade names of YD-127, YD-128G, YD-128S, YD-128CA, YD-8125, YD-825, and YD-825GHS, manufactured by Mitsubishi chemical corporation, bisphenol A type liquid epoxy resins, trade names of jER806, jER806H, jER807, YL983U, and the trade names of EPICLON830, CRP, EXA-830, EXA-LVP, EXA-LV, and the trade names of YDF 170, and YDF-835-170, manufactured by Mitsubishi chemical corporation, respectively, Bisphenol F-type liquid epoxy resins such as YDF-8170C, YDF-870GS, trade names YX8000 and YX8034 manufactured by Mitsubishi chemical, a hydrogenated bisphenol A-type liquid epoxy Resin such as trade name ST-3000 manufactured by Nippon Metal chemical, a trade name jER152 manufactured by Mitsubishi chemical, a novolak-type liquid epoxy Resin such as trade name EPICLONN-730A manufactured by DIC, a naphthalene-type liquid epoxy Resin such as trade name EPICLONHP-4032D manufactured by DIC, a dicyclopentadiene-type liquid epoxy Resin such as trade name Adeka Resin (registered trade name) EP-40 4088S, EP-4088L manufactured by ADEKA, NBR-modified epoxy resins such as trade name EPLONTSR-960 and TSR-601 manufactured by DIC, and an NBR-modified epoxy Resin such as trade name jER manufactured by Mitsubishi chemical, JeR872, dimer acid-modified epoxy resins such as the trade name Epoto (registered trademark) YD-172 manufactured by Nissin Tekken chemical Co., Ltd.), butadiene-modified epoxy resins such as the trade names JP-100, JP-200, JP-400 manufactured by Nippon Cauda (Kao Co., Ltd.), alicyclic epoxy resins such as the trade names CELLOXIDE (registered trademark) 2021P, 2081 manufactured by Daicel chemical Co., Ltd.), triglycidyl isocyanurate such as TEPIC (registered trademark) manufactured by Nissan chemical Co., Ltd., and the trade names Denacol (registered trademark) EX-1000 series, Denacol series, DenacoDLC series, Denalex (registered trademark) series, EX991 and the like manufactured by Nagase Chemtex (Kabushiki Co., Ltd.) can be used alone or in combination of plural kinds.

As the epoxy resin, an epoxy resin which is semi-solid or solid at 25 ℃ may be used. The epoxy resin which is in a semi-solid state or a solid state at 25 ℃ may be modified, and may contain a sulfur atom, a nitrogen atom, a phosphorus atom, or the like in the molecular skeleton. For example, there may be mentioned: bisphenol a-type epoxy resins, bisphenol F-type epoxy resins, hydrogenated products thereof, novolac-type (Phenolic novolac) epoxy resins, Cresol novolac-type (Cresol novolac) epoxy resins, biphenyl-type epoxy resins, naphthalene-type epoxy resins, dicyclopentadiene-type epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, and the like. As commercial products of these, for example, there are listed: trade names of Jer1001, Jer1004, Jer1007, and Jer1010 manufactured by Mitsubishi chemical corporation, trade names of EpotoxyD-134, YD-011, YD-014, and YD-017 manufactured by New Nippon Kabushiki Kaisha, bisphenol A type epoxy resins such as trade names of EPICLON860, 1050, 1055, 2050, 3050, 4050, and 7050 manufactured by DIC Katsubishi chemical corporation, trade name of Jer4004P, Jer4005P, Jer400 4007P, and Jer4010P manufactured by Mitsubishi Kabushiki Kaisha, bisphenol F type epoxy resins such as EpotoYDF-2004, and hydrogenated bisphenol A type epoxy resins such as EPST-4000D manufactured by New Nippon Kabushiki Kaisha, trade name of EPOTO YDF-154, registered trade names of EPER-PN-770, EPICON NITRIPTON NITRIKANTHON Kabushiki Kaisha, Novolac type epoxy resins such as EPPN-501H, EPPN-501HY, EPPN-502H, NC-2000L, trade name DEN-438 manufactured by Dow Chemical company, trade names EPICLONN-660, N-665, N-670, N-673, N-680, N-690, N-695 manufactured by DIC (Co., Ltd.), cresol Novolac type epoxy resins such as EpotoYDCN-700-7 and YDCN-700-10 manufactured by Nissan Kagaku K.K., trade names EOCN (registered trade name) -1020 and EOCN-102S, EOCN-103S, EOCN-104S manufactured by Nippon Kagaku K.K., trade names YX4000 and YX H manufactured by Mitsubishi Chemical Co., Ltd., trade name NC-3000L, and NC-3000L manufactured by NC-Chemical Co., Ltd, Biphenyl type epoxy resins such as NC-3000H, NC-3100, trade names EPICLONHP-4700, HP-4710, HP-4770, HP-5000, and HP-6000 manufactured by DIC (Co., Ltd.), and trade names NC-7000L manufactured by Nippon Kagaku (K.K.), naphthalene type epoxy resins such as NC-7300L, dicyclopentadiene type epoxy resins such as EPICLONHP-7200L, HP-7200, HP-7200H, HP-7200HH and HP-7200HHH, tradename XD-1000, manufactured by Nippon Chemicals, cycloaliphatic epoxy resins such as EHPE (registered trademark) 3150, manufactured by Daicel chemical industry, phosphorus-containing epoxy resins such as EXA-9726, manufactured by DIC, and the like, which are used singly or in combination of two or more.

Epoxy resins and phosphorus compounds usually contain chlorine as an impurity in the production process. However, from the viewpoint of reducing environmental load, it is necessary to reduce the amount of halogen, and it is known that the insulation property is lowered when the amount of chlorine, particularly hydrolyzable chlorine, is large, and therefore the total amount of chlorine in the nonvolatile components in the adhesive composition is preferably 500ppm or less, more preferably 300ppm or less.

In order to improve coating stability within a range not impairing the effects of the present invention, an organic solvent having a surface tension of 33dyn/cm or less may be added to the adhesive composition of the present invention in addition to the above-mentioned solvent. For example, there may be mentioned: aromatic solvents such as toluene and xylene; aliphatic solvents such as hexane, heptane and octane, and alcohol solvents such as methanol, ethanol, propanol, butanol and isopropanol; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and cyclopentanone; ether solvents such as diethyl ether and tetrahydrofuran; ester solvents such as ethyl acetate, butyl acetate, isobutyl acetate, and the like; and acetate solvents such as diethylene glycol monoethyl ether acetate and diethylene glycol monobutyl ether acetate, which may be used alone or in combination of two or more. The amount of the solvent to be mixed is not particularly limited as long as the resin having an imide bond is dissolved, and is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, and further preferably 200 parts by mass or more, per 100 parts by mass of the resin having an imide bond. Further, it is preferably 2000 parts by mass or less, more preferably 1500 parts by mass or less, and further preferably 1000 parts by mass or less.

In order to improve coating stability, a surface conditioner may be added to the adhesive composition of the present invention within a range not to impair the effects of the present invention. From the viewpoint of adhesiveness, the surface conditioner is preferably one having a boiling point of 150 ℃ or lower, more preferably 120 ℃ or lower. Specifically, the solvent is not particularly limited, and may be Surfinol (registered trademark) 104E, 104H, 104A, 104PA, 104S, 420, 440, 465, 485, SE-F, Olfine (registered trademark) exp.4001, 4123, 4200, 4300 and the like, which are manufactured by shin chemical industry (ltd.), and they may be used alone or in combination of two or more. The amount of the surface conditioner to be mixed is preferably 0.01 to 0.5% by mass, and more preferably 0.05 to 0.3% by mass, based on the total mass of the resin having an imide bond and the epoxy resin in the adhesive composition. When the amount of the surface conditioner is small, the coating stability may not be easily obtained, and when the amount is large, the adhesiveness may not be easily developed.

In order to improve the insulation reliability under a high-temperature and high-humidity environment at a higher level within a range not impairing the effects of the present invention, a highly heat-resistant resin may be added to the adhesive composition of the present invention. The high heat-resistant resin is preferably a resin having a glass transition temperature of 200 ℃ or higher, and more preferably a resin having a glass transition temperature of 250 ℃ or higher. The solvent is not particularly limited, and specifically, the following may be mentioned: polyimide resins, polyamide-imide resins, polyether ether ketone resins, and the like. In addition, the highly heat-resistant resin is preferably dissolved in a solvent. As a substance satisfying these conditions, a resin in which the acid anhydride of a polycarboxylic acid having an aromatic ring is 90 mol% or more, with the structural unit derived from the total acid component being 100 mol%, is preferable, and a polyamideimide resin is most preferable among them. The specific raw materials are as described above.

In the adhesive composition of the present invention, a glycidylamine-type epoxy resin may be added in addition to the above epoxy resin in order to accelerate curing within a range not to impair the effects of the present invention. The amount of the glycidylamine-type epoxy resin added is preferably 0.01 to 5% by mass, more preferably 0.05 to 2% by mass, based on the total mass of the resin having an imide bond and the epoxy resin in the adhesive composition. When the amount of the glycidyl amine type epoxy resin to be mixed is small, the effect of accelerating the curing may not be obtained. When the amount of the functional group is large, the effect of promoting the curing of the epoxy groups is large, and the reaction between the reactive functional group of the resin having an imide bond and the epoxy group may not proceed sufficiently, resulting in a decrease in heat resistance and adhesiveness. Examples of the glycidyl amine type epoxy resin include a trade name of TETRAD (registered trademark) -X, TETRAD-C manufactured by Mitsubishi Gas chemical, a trade name of jER630 and jER604 manufactured by Mitsubishi chemical, a trade name of YH-434L and YH-434L manufactured by Nissan iron King chemical, a trade name of Adeka ResinEP-3950S, EP-3950L, EP-3980S manufactured by ADEKA, a trade name of GAN (registered trademark) manufactured by Nippon Kagaku K., a trade name of GAN (registered trademark), GOT (registered trademark), and the like, and they may be used alone or in combination of two or more.

The adhesive composition of the present invention may contain a curing agent or a curing accelerator for an epoxy resin, as long as the effects of the present invention are not impaired. The curing agent is not particularly limited as long as it is a compound that reacts with the epoxy resin, and examples thereof include: the amine-based curing agent includes a compound having a phenolic hydroxyl group, a compound having a carboxylic acid, a compound having an acid anhydride, and the like. The curing catalyst is not particularly limited as long as it promotes the reaction between the epoxy resin, the resin having an imide bond, and the curing agent, and examples thereof include imidazole derivatives such as 2MZ, 2E4MZ, C11Z, C17Z, 2PZ, 1B2MZ, 2MZ-CN, 2E4MZ-CN, C11Z-CN, 2PZ-CN, 2PHZ-CN, 2 AZ-CNS, 2E4MZ-CNS, 2PZ-CNS, 2MZ-AZINE, 2E4MZ-CNS, C11 ZANE, 2MA-OK, 2 ZIP 4MHZ, 2PHZ, 2P4BHZ, and guanidines such as acetoguanamine and benzoguanamine; polyamines such as diaminodiphenylmethane, m-phenylenediamine, m-xylylenediamine, diaminodiphenylsulfone, dicyandiamide, urea derivatives, melamine and polyhydrazide, organic acid salts thereof and/or epoxy adducts thereof; an amine complex of boron trifluoride; triazine derivatives such as ethyldiamino-S-triazine, 2, 4-diamino-S-triazine and 2, 4-diamino-6-xylyl-S-triazine, tertiary amines such as trimethylamine, triethanolamine, N, N-dimethyloctylamine, N-benzyldimethylamine, pyridine, N-methylmorpholine, hexa (N-methyl) melamine, 2,4, 6-tris (dimethylaminophenol), tetramethylguanidine, DBU (1, 8-diazabicyclo [ 5.4.0 ] -7-undecene), DBN (1, 5-diazabicyclo [ 4.3.0 ] -5-nonene), organic acid salts and/or tetraphenylborate thereof, polyvinylphenol bromide, bromine, and the like, Organic phosphines such as tributylphosphine, triphenylphosphine and tris-2-cyanoethylphosphine, quaternary phosphonium salts such as tri-n-butyl (2, 5-dihydroxyphenyl) phosphonium bromide, hexadecyltributylphosphonium chloride and tetraphenylphosphonium tetraphenylborate, quaternary ammonium salts such as benzyltrimethylammonium chloride and phenyltributylammonium chloride, photocationic polymerization catalysts such as the above-mentioned polycarboxylic acid anhydride, diphenyliodonium tetrafluoroborate, triphenylsulfonium hexafluoroantimonate, 2,4, 6-triphenylthiopyridium hexafluorophosphate, Irgacure 261 (manufactured by Ciba specialty Chemicals) and Optoma-SP-170 (manufactured by ADEKA), styrene-maleic anhydride resin, equimolar reaction products of phenyl isocyanate and dimethylamine, equimolar reaction products of organic polyisocyanates such as toluene diisocyanate and isophorone diisocyanate and dimethylamine, etc., they can be used alone, a plurality of them may be used in combination.

The adhesive composition of the present invention may contain a silane coupling agent for the purpose of improving the adhesion within a range not to impair the effects of the present invention. The silane coupling agent is not particularly limited as long as it is a conventionally known one. As specific examples thereof, there can be cited: aminosilane, mercaptosilane, vinylsilane, epoxysilane, methacrylicsilane, isocyanatosilane, ketiminosilane, mixtures or reactants thereof, or a compound obtained by reacting them with a polyisocyanate. Examples of the silane coupling agent include: aminosilanes such as 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-aminopropylmethyldimethoxysilane, 3-aminopropylethyldiethoxysilane, bistrimethoxysilylpropylamine, bisdimethoxysilylpropylamine, bisethoxydiethoxysilylpropylamine, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane, N-2- (aminoethyl) -3-aminopropylmethyldimethoxysilane, N-2- (aminoethyl) -3-aminopropyltrimethoxysilane and N-2- (aminoethyl) -3-aminopropylethyldiethoxysilane, Mercaptosilanes such as gamma-mercaptopropyltrimethoxysilane, gamma-mercaptopropyltriethoxysilane, gamma-mercaptopropylmethyldimethoxysilane, gamma-mercaptopropylmethyldiethoxysilane and gamma-mercaptopropylethyldiethoxysilane, vinylsilanes such as vinyltrimethoxysilane, vinyltriethoxysilane and tris- (2-methoxyethoxy) vinylsilane, epoxysilanes such as gamma-glycidoxypropyltrimethoxysilane, gamma-glycidoxypropyldimethylethoxysilane, gamma-glycidoxypropylmethyldiethoxysilane, beta- (3, 4-epoxyaminoethyl) ethylmethyldimethoxysilane, gamma-glycidoxypropyltrimethoxysilane and beta- (3, 4-epoxyaminoethyl) ethyltrimethoxysilane, Methacrylic silanes such as 3-methacryloxypropylmethyldimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropylmethyldiethoxysilane and 3-methacryloxypropyltriethoxysilane, isocyanate silanes such as isocyanate propyltriethoxysilane and isocyanate propyltrimethoxysilane, ketimine silanes such as ketiminized propyltrimethoxysilane and ketiminized propyltriethoxysilane, which may be used alone or in combination. Among these silane coupling agents, epoxy silane is preferable in terms of improvement in heat resistance and moist heat resistance because it has a reactive epoxy group and is therefore capable of reacting with a resin having an imide bond. The amount of the silane coupling agent added is preferably 0 to 3% by mass, more preferably 0 to 2% by mass, based on the nonvolatile component of the resin agent composition. When the amount is large, the heat resistance may be lowered.

The filler may be added to the adhesive composition of the present invention as an organic/inorganic filler in an amount not to impair the effects of the present invention and for the purpose of improving solder heat resistance. Examples of the organic filler include powdery heat-resistant resins such as polyimide and polyamideimide. Examples of the inorganic filler include: silicon dioxide (SiO)₂) Alumina (Al)₂O₃) Titanium dioxide (TiO)₂) Tantalum oxide (Ta)₂O₅) Zirconium oxide (ZrO)₂) Silicon nitride (Si)₃N₄) Barium titanate (BaO. TIO)₂) Barium carbonate (BaCO)₃) Lead titanate (PbO. TiO)₂) Lead zirconate titanate (PZT), lead lanthanum zirconate titanate (PLZT), gallium oxide (Ga)₂O₃) Spinel (MgO. Al)₂O₃) Mullite (3 Al)₂O₃.2SiO₂) Cordierite (2 MgO.2Al)₂O₃·5SiO₂) Talc (3 MgO.4SiO)₂·H₂O), aluminum Titanate (TIO)₂-Al₂O₃) And zirconia (Y) containing yttrium oxide₂O₃-ZrO₂) Barium silicate (BaO 8 SiO)₂) Boron Nitride (BN), calcium carbonate (CaCO)₃) Calcium sulfate(CaSO₄) Zinc oxide (ZnO), magnesium titanate (MgO. TiO)₂) Barium sulfate (BaSO)₄) Among them, silica is preferable because of its effect of facilitating dispersion and improving heat resistance. These may be used alone or in combination of two or more. The amount of the organic/inorganic filler added is preferably 1 to 30% by mass, more preferably 3 to 15% by mass, based on the nonvolatile components of the adhesive composition. When the amount is large, the adhesive coating may be brittle, and when the amount is small, the effect of improving the heat resistance may not be sufficiently obtained.

An example of the method for producing the adhesive composition of the present invention will be described. A solvent solution of a resin having an imide bond (hereinafter, also referred to as a resin varnish having an imide bond), a solvent solution of an epoxy resin (hereinafter, also referred to as an epoxy resin varnish), a phosphorus compound of the general formula (1) and the like are mixed and stirred to make the system uniform. When a filler is used, a slurry of the above solvent is added as a filler, and the mixture is further stirred. Thus, the adhesive composition of the present invention was obtained. In addition, when obtaining the adhesive composition, a diluting solvent, a curing accelerator, or the like may be added as necessary in order to adjust the viscosity.

The adhesive composition of the present invention can be used as a preferable adhesive composition for a flexible printed wiring board. A layer of the adhesive composition obtained by applying the adhesive composition to a substrate such as a film and drying the composition is referred to as an adhesive layer, and examples of the portion of the flexible printed wiring board where the adhesive composed of the adhesive composition is used include: an adhesive film for a reinforcing plate, an adhesive film for an interlayer, a cover film, and a copper-clad laminate.

The adhesive film is a film composed of "protective film/adhesive layer" or "protective film/adhesive layer/protective film". In some cases, an insulating film layer is provided in the adhesive layer, and the structure is "protective film/adhesive layer/insulating film/adhesive layer/protective film". Flexible printed wiring boards are often used as adhesive films for reinforcing plates and as adhesive films between layers.

The insulating film is a film having a thickness of 1 to 200 μm and made of a plastic such as polyimide, polyamideimide, polyester, polyphenylene sulfide, polyether sulfone, polyether ether ketone, aromatic polyamide, polycarbonate, or polyarylate, and a plurality of the films can be selected and laminated.

The protective film is not particularly limited as long as it can be peeled off without impairing the properties of the adhesive, and examples thereof include: plastic films such as polyethylene, polypropylene, polyolefin, polyester, polymethylpentene, polyvinyl chloride, polyvinylidene fluoride, and polyphenylene sulfide; and films obtained by applying silicone, fluoride or other release agents thereto; paper to which they are laminated; paper impregnated or coated with a releasable resin, and the like.

The cover film is a film composed of an "insulating film/adhesive layer" or an "insulating film/adhesive layer/protective film".

The copper-clad laminate comprises a copper foil/adhesive layer/insulating film or a copper foil/adhesive layer/insulating film/adhesive layer/copper foil. The copper foil is not particularly limited, and a rolled copper foil or an electrolytic copper foil conventionally used for flexible printed wiring boards can be used.

In any of the above applications, the adhesive composition is obtained by applying the adhesive composition to a film or a copper foil as a base material, drying the adhesive composition with a solvent, thermally pressing the adhesive composition against an adherend, and performing a heat curing treatment. For the purpose of adjusting the fluidity of the adhesive composition at the time of thermocompression bonding, after drying the solvent, the adhesive film and the cover film may be subjected to a heat treatment to partially react the resin having imide bonds and the phosphorus compound having reactive functional groups with the epoxy resin. The state before thermocompression bonding is referred to as a B stage.

In any of the above applications, after heat curing, adhesiveness, heat resistance and insulation reliability are required, and further flame retardancy is preferable. The adhesive film and the cover film are usually subjected to processes such as winding, storage, cutting, and punching in a B-stage state, and flexibility is required in the B-stage state. On the other hand, since the copper-clad laminate is usually thermocompression bonded and thermally cured immediately after the formation of the B-stage state, flexibility in the B-stage state as in the case of the coverlay film and the adhesive film is not required.

The adhesive film and the cover film of the present invention preferably have a residual solvent content in the adhesive layer in a B-stage state of less than 1.5 mass%, more preferably 1.0 mass% or less. The residual solvent is a solvent used in the adhesive composition that is not completely removed in the B-stage process, and when a plurality of solvents are used in combination, a solvent having a higher boiling point remains. When the amount of the residual solvent is large, insulation reliability may be lowered, and as described above, the amount of the residual solvent in the adhesive layer in the B-stage state is preferably less than 1.5% by mass, and more preferably 1.0% by mass or less.

The adhesive composition of the present invention, which comprises a resin having an imide bond and a phosphorus compound of the general formula (1), is excellent in adhesion, heat resistance, flame retardancy and insulation reliability. Further, the phosphorus compound of the general formula (1) is excellent in solvent solubility and thus excellent in handling properties. Further, the phosphorus compound of the general formula (1) has excellent compatibility with a resin having an imide bond, a large molecular weight, and a small plasticizing effect, and therefore has a property of being less likely to bleed out in a high-temperature and high-humidity environment. Therefore, the adhesive composition of the present invention comprising the resin having an imide bond and the phosphorus compound of the general formula (1) exhibits high insulation reliability.

Examples

The effects of the present invention will be verified by examples below, but the present invention is not limited to these examples. The characteristics in the examples were evaluated by the following methods. In the examples and comparative examples, the term "part" alone means part by mass.

Logarithmic viscosity:

the resin having imide bonds was dissolved in N-methyl-2-pyrrolidone so that the polymer concentration was 0.5 g/dl. The solution viscosity and the solvent viscosity of the resulting solution were measured at 30 ℃ using an Ubbelohde (Ubbelohde) viscosity tube, and the logarithmic viscosity was calculated according to the following formula.

Logarithmic viscosity (dl/g) ═ ln (V2/V1) ]/V3

In the above formula, V1 represents the viscosity of the resin solution measured by a Ubbelohde tube, and V2 represents the viscosity of the solvent measured by a Ubbelohde tube. V1 and V2 were determined from the time taken for the resin solution and the solvent (N-methyl-2-pyrrolidone) to pass through the capillary of the viscosity tube. V3 represents the resin concentration (g/dl).

Acid value:

0.1g of a resin having an imide bond was dissolved in 20ml of N-methyl-2-pyrrolidone, thymolphthalein was used as an indicator, and titration was performed with a 0.1N KOH ethanol solution, and 10/resin was measured⁶g corresponding carboxyl equivalent (eq/ton), and calculating the acid value according to the following formula.

Acid value (mgKOH/g) ([ carboxyl equivalent (eq/ton) × 56.12 ]/1000)

Glass transition temperature:

the solution of the resin having imide bonds was applied to the glossy surface of the copper foil, and dried for 3 minutes by a hot air dryer at 140 ℃. Thereafter, the resin was dried at 250 ℃ for 30 minutes under a nitrogen atmosphere, thereby obtaining a resin with a copper foil. Thereafter, the copper foil was etched, thereby preparing a resin film having a thickness of 20 μm. The glass transition temperature of the resin film prepared as described above was measured by a TMA (thermo-mechanical analyzer) stretching method under conditions of a load of 50mN and a temperature rise rate of 10 ℃/min.

Adhesion:

a solution of the adhesive composition was applied to a Polyimide (PI) film (Apical (registered trademark) 12.5NPI manufactured by Kaneka), the thickness of the adhesive layer after drying was set to 20 μm, and the sample (PI film/adhesive layer) in a B-stage state was obtained by drying at 140 ℃ for 3 minutes by a hot air circulation dryer. The adhesive-coated surface of the B-staged sample (PI film/adhesive layer) and a rolled copper foil (BHY-13F-T manufactured by JX metal: 18 μm in thickness) were thermocompression bonded at 160 ℃ under a reduced pressure of 20kgf for 60 seconds using a vacuum laminator. Thereafter, the cured product was heated at 170 ℃ for 3 hours. The cured sample (PI film/adhesive layer/rolled copper foil) was peeled off from the polyimide film at a speed of 50mm/min in a direction of 90 ℃ in a gas atmosphere at 25 ℃ using a tensile tester (Autograph AG-X plus manufactured by Shimadzu), and the adhesive strength was measured.

Very good: the adhesive strength is more than 0.7N/mm or the polyimide film material is damaged

O: the adhesive strength is more than 0.5N/mm and less than 0.7N/mm

X: the bonding strength is less than 0.5N/mm

Solder heat resistance:

samples (PI film/adhesive layer/rolled copper foil) obtained by heat curing in the same manner as in the evaluation of adhesiveness were prepared, cut to 20mm square, and floated for 1 minute with the polyimide surface on top in a solder bath at 300 ℃. The appearance was evaluated.

O: without swelling or peeling

X: presence of swelling or peeling

Flame retardancy:

the adhesive composition solution was applied to a polyimide film (Apical 12.5NPI manufactured by Kaneka) to give a thickness of the adhesive layer after drying 20 μm, and the sample was dried at 140 ℃ for 3 minutes by a hot air circulation dryer to obtain a sample (PI film/adhesive layer) in a B-stage state. The adhesive-coated surface of the B-stage sample (PI film/adhesive layer) was thermocompression bonded to a polyimide film (Apical 12.5NPI manufactured by Kaneka) using a vacuum laminator at 160 ℃, 20kgf, and under a reduced pressure of 60 seconds. Thereafter, heat curing was performed at 170 ℃ for 3 hours. The cured samples (PI film/adhesive layer/PI film) were evaluated for flame retardancy based on the UL-94VTM standard.

O: equivalent to VTM-0

X: not satisfying VTM-0

Insulation reliability:

the adhesive composition solution was applied to a polyimide film (Apical 12.5NPI manufactured by Kaneka) to give a thickness of the adhesive layer after drying 20 μm, and the adhesive layer was dried at 140 ℃ for 3 minutes by a hot air circulation dryer to obtain a sample (PI film/adhesive layer) in a B-stage state. The adhesive-coated surface of the B-stage sample (PI film/adhesive layer) was thermocompression bonded to a single-sided copper-clad laminate (trade name ESPANEX (registered trademark) MC12-25-00CEM manufactured by seiki-kunjin chemical corporation) etched into a comb pattern with L/S of 50/50 μm using a vacuum laminator at 160 ℃, 20kgf, and 60 seconds reduced pressure. Thereafter, heat curing was performed at 170 ℃ for 3 hours. The cured sample (PI film/adhesive layer/single-sided copper-clad laminate) was applied with a voltage of 200V for 250 hours in an environment of 85 ℃ and 85% humidity.

Very good: the resistance value after 250 hours was 1X 10¹⁰Omega or more, and no dendrite

O: the resistance value after 250 hours was 1X 10⁹Omega is more than or equal to 1 multiplied by 10¹⁰Omega, and no dendrites are produced

X: the resistance value after 250 hours is less than 1X 10⁹Omega or generation of dendrites

X: short circuit within 250 hours

Polymerization of resins 1 to 2 having imide bond:

polymerization of the resin having an imide bond was performed with the resin components (mol%) of the raw materials shown in table 1. Specifically, the polymerization was carried out as follows.

Polymerization of resin 1 having imide bond

In a four-necked separable flask equipped with a stirrer, a cooling tube, a nitrogen introducing tube and a thermometer, 110.47g (0.575 mol) of TMA (trimellitic anhydride), 80.90g (0.40 mol) of sebacic acid, 87.5g (0.025 mol) of NBR (acrylonitrile butadiene rubber modified at both terminal carboxyl groups), 250.25g (1.00 mol) of MDI (diphenylmethane-4, 4' -diisocyanate) and 714.50g of dimethylacetamide were charged, and the concentration of the resin component after decarboxylation was increased to 40 mass%, and the reaction was carried out by raising the temperature to 100 ℃ under nitrogen for 2 hours and further raising the temperature to 150 ℃ for 5 hours. Thereafter, 396.94g of dimethylacetamide was added to dilute the mixture so that the concentration of the resin component became 30 mass%, thereby obtaining a solution of the resin 1 having imide bonds.

Polymerization of resin 2 having imide bond

In a four-necked separable flask equipped with a stirrer, a cooling tube, a nitrogen introduction tube and a thermometer, 192.13g (1.00 mol) of trimellitic anhydride and 225.23g (0.90 mol) of diphenylmethane-4, 4' -diisocyanate were charged, 494.05g of N-methyl-2-pyrrolidone was added to adjust the concentration of the resin component after decarboxylation to 40 mass%, and the reaction was carried out while raising the temperature to 100 ℃ under nitrogen for 2 hours, and further, while raising the temperature to 150 ℃ for 5 hours. Thereafter, 117.63g of dimethylacetamide was added to dilute the mixture so that the concentration of the resin component became 35 mass%, thereby obtaining a solution of the resin 2 having imide bonds.

[ Table 1]

TMA: trimellitic anhydride

NBR: acrylonitrile butadiene rubber modified by carboxyl at two ends

MDI: diphenylmethane-4, 4' -diisocyanate

Preparation of a solution of the adhesive composition:

the adhesive compositions of examples 1 to 6 and comparative examples 1 to 4 were prepared in the form of a dimethylacetamide solution or an N-methyl-2-pyrrolidone solution according to the adhesive formulation (solid content (mass%) shown in Table 2, and the above properties were evaluated.

As is clear from table 2, the adhesive compositions of examples 1 to 6 satisfying the conditions of the present invention exhibited excellent results in terms of adhesiveness, solder heat resistance, flame retardancy, and insulation reliability, and on the other hand, any of the characteristics of comparative example 1 not containing a phosphorus compound, comparative examples 2 and 3 not containing a phosphorus compound of general formula (1), and comparative example 4 not containing a resin having an imide bond were not satisfied.

[ Table 2]

UR 3500: polyester urethane resin produced by Toyobo Co., Ltd

jER 152: novolac type epoxy resin (liquid) manufactured by Mitsubishi chemical corporation

YDF 8170C: bisphenol F type epoxy resin (liquid) manufactured by Nissian iron-on-gold chemical Co., Ltd

YDCN 700-7: cresol novolac type epoxy resin (liquid) manufactured by Nissian iron-on-gold chemical (Kabushiki Kaisha)

Non-75: the phosphonic acid derivative manufactured by Mitsubishi oil chemical industry (Kabushiki Kaisha) comprises the chemical formula (8)

HCA: the phosphonic acid derivative manufactured by Sanguang (Kabushiki Kaisha) contains the chemical formula (5)

BCA: the phosphonic acid derivative manufactured by Sanguang (Kabushiki Kaisha) contains the chemical formula (6)

[ possibility of Industrial use ]

The adhesive composition of the present invention, which is excellent in adhesiveness, heat resistance, flame retardancy, workability, and insulation reliability by using a resin having an imide bond and a specific phosphorus compound in combination, is very suitable for an adhesive film, a coverlay film, a copper-clad laminate, and the like.

Claims

1. An adhesive composition, characterized by comprising: a resin having an imide bond and a phosphorus compound represented by the general formula (1),

[ chemical formula 1]

In the general formula (1), n is an integer of 2-6, and a plurality of X are each independently CH₂Or O.

2. The adhesive composition according to claim 1, wherein the phosphorus compound represented by the general formula (1) is a phosphorus compound represented by the general formula (2) and/or a phosphorus compound represented by the general formula (3),

[ chemical formula 2]

In the general formula (2), X is CH₂Or an oxygen-containing gas,

[ chemical formula 3]

In the general formula (3), X is CH₂Or O.

3. The adhesive composition according to claim 1 or 2, wherein the resin having an imide bond is a polyimide resin, a polyamideimide resin, a polyetherimide resin, a polyetheretherketone resin, a polyesterimide resin, or a polycarbonate imide resin.

4. The adhesive composition according to any one of claims 1 to 3, wherein trimellitic anhydride is contained as a copolymerization component of the resin having an imide bond.

5. The adhesive composition according to any one of claims 1 to 4, wherein the resin having an imide bond contains a copolymer component of acrylonitrile butadiene rubber modified with carboxyl groups at both ends.

6. The adhesive composition according to any one of claims 1 to 5, further comprising an epoxy resin.

7. An adhesive composition according to claim 6, wherein said epoxy resin is liquid at 25 ℃ and has 2 or more epoxy groups in 1 molecule.

8. The adhesive composition according to any one of claims 1 to 7, which is used for printed wiring boards.

9. An adhesive film comprising the adhesive composition according to any one of claims 1 to 8.

10. A cover film comprising the adhesive film according to claim 9.

11. A copper-clad laminate characterized by using the adhesive film according to claim 9.

12. A flexible printed wiring board, characterized in that the coverlay film according to claim 10 or the copper-clad laminate according to claim 11 is used.