JP7305315B2 - Curable resin composition, adhesive, adhesive film, coverlay film, and flexible copper-clad laminate - Google Patents

Description

TECHNICAL FIELD The present invention relates to a curable resin composition that exhibits excellent flexibility and workability before curing, and exhibits excellent adhesiveness and heat resistance after curing. The present invention also relates to an imide compound that can be used in the curable resin composition, and an adhesive, an adhesive film, a coverlay film, and a flexible copper-clad laminate using the curable resin composition. .

Curable resins such as epoxy resins, which have low shrinkage and are excellent in adhesiveness, insulation, and chemical resistance, are used in many industrial products. Particularly in applications for electronic devices, curable resin compositions that give good results in solder reflow tests for short-term heat resistance and thermal cycle tests for repeated heat resistance are often used.

For example, Patent Literatures 1 and 2 disclose a curable resin composition containing an epoxy resin and an imide compound as a curing agent. However, since imide compounds generally have hard and brittle properties at room temperature, the curable resin compositions disclosed in Patent Documents 1 and 2 have problems with flexibility, workability, fluidity, etc. at room temperature. there were.
As a curable resin composition with improved workability, fluidity, etc., Patent Document 3 discloses a curable resin composition containing a liquid epoxy resin and an imide compound having a specific reactive functional group. ing. However, even the curable resin composition disclosed in Patent Document 3 does not have sufficient fluidity, and when the content of the liquid epoxy resin is increased in order to further improve the fluidity, the heat resistance and adhesion deteriorate. There was a problem of
Further, in Patent Document 4, a curable resin before curing is prepared by dispersing a nitrile rubber component in a resin mixture containing an imide compound having a specific reactive functional group, an epoxy resin, and a bismaleimide-triazine resin. A method for improving the flexibility of a composition is disclosed. However, the method disclosed in Patent Document 4 has a problem that the nitrile rubber component deteriorates the heat resistance of the cured product.

JP-A-61-270852 Japanese Patent Publication No. 2004-502859 JP-A-2007-91799 JP-A-7-224269

An object of the present invention is to provide a curable resin composition which is excellent in flexibility and workability before curing, and excellent in adhesiveness and heat resistance after curing. Further, the present invention provides an imide compound that can be used in the curable resin composition, and an adhesive, an adhesive film, a coverlay film, and a flexible copper-clad laminate using the curable resin composition. intended to provide

The present invention is a curable resin composition containing a curable resin and an imide compound, having a glass transition temperature of less than 25°C before curing, and a 5% weight loss temperature of the cured product of 320°C or higher. be.
Further, the present invention provides an acid dianhydride containing a structure represented by the following formulas (1-1), (1-2), (1-3), (1-4), or (1-5) It is an imide compound having a residue and a diamine residue.

All or part of the hydrogen atoms in the aromatic rings in formulas (1-1) to (1-5) may be substituted.
The present invention will be described in detail below.

The present inventors have found that a curable resin composition whose glass transition temperature before curing is less than a specific temperature and whose 5% weight loss temperature of the cured product is a specific temperature or higher is before curing (B stage) has excellent flexibility and processability, and after curing, it has excellent adhesiveness and heat resistance, leading to the completion of the present invention. In addition, the present inventors have found an imide compound having a specific structure as an imide compound that can be used in such a curable resin composition, thereby completing the present invention.

The curable resin composition of the present invention has a glass transition temperature of less than 25°C before curing. When the glass transition temperature before curing is less than 25°C, the curable resin composition of the present invention is excellent in flexibility and workability before curing. A preferable upper limit of the glass transition temperature before curing is 23°C, and a more preferable upper limit is 20°C.
Although there is no particular lower limit for the glass transition temperature before curing, the practical lower limit is -10°C.
In the present specification, the "glass transition temperature before curing" is measured using a differential scanning calorimeter at a heating rate of 10 ° C./min from the inflection point of the endothermic peak accompanying the glass transition. can ask. Examples of the differential scanning calorimeter include DSC7000 series (manufactured by Hitachi High-Tech Science).

The curable resin composition of the present invention has a 5% weight loss temperature of 320° C. or higher. When the 5% weight loss temperature of the cured product is 320° C. or higher, the curable resin composition of the present invention has excellent heat resistance after curing, and can be suitably used as a heat-resistant adhesive for vehicles. . A preferable lower limit of the 5% weight loss temperature of the cured product is 340°C, and a more preferable lower limit is 350°C.
Although there is no particular upper limit for the 5% weight loss temperature of the cured product, the practical upper limit is 450°C.
The 5% weight loss temperature can be derived by performing thermogravimetric measurement using a thermogravimetry device under conditions of temperature elevation from 30°C to 500°C at a temperature elevation rate of 10°C/min. Examples of the thermogravimetry apparatus include TG/DTA6200 (manufactured by Hitachi High-Tech Science).

The curable resin composition of the present invention contains an imide compound.
As a method for adjusting the glass transition temperature before curing and the 5% weight loss temperature of the cured product within the ranges described above, a method using the imide compound of the present invention as the imide compound is suitable.

The imide compound of the present invention is an acid dianhydride containing a structure represented by the above formula (1-1), (1-2), (1-3), (1-4), or (1-5) has a substance residue. Among others, the imide compound of the present invention more preferably has an acid dianhydride residue containing a structure represented by the above formula (1-1), (1-2), or (1-3). .
As used herein, the term "residue" means the structure of a portion other than the functional group used for bonding.

All or part of the hydrogen atoms in the aromatic rings in formulas (1-1) to (1-5) may be substituted. Examples of the substituent when the hydrogen atom of the aromatic ring is substituted include a hydroxyl group and the like.

The acid dianhydride from which the acid dianhydride residue is derived can be obtained, for example, by the following method.
That is, first, an aromatic diol compound is reacted with a hydrocarbon compound having two cyano groups and one reactive group to obtain a tetracyano compound having two cyano groups at both ends. Then, by hydrolyzing the obtained tetracyano compound, a tetracarboxylic acid having two carboxyl groups at both ends is obtained. Thereafter, the resulting tetracarboxylic acid is subjected to dehydration condensation to obtain the acid dianhydride from which the acid dianhydride residue is derived.

The aromatic diol compound preferably has a melting point of 156° C. or lower. That is, the imide compound of the present invention preferably has an acid dianhydride residue containing a structure derived from an aromatic diol compound having a melting point of 156° C. or lower, and a diamine residue. When the aromatic diol compound has a melting point of 156° C. or less, the resulting curable resin composition is superior in flexibility and workability before curing. A more preferable upper limit of the melting point of the aromatic diol compound is 150°C, and a further preferable upper limit is 140°C.
Although there is no particular lower limit for the melting point of the aromatic diol compound, the practical lower limit is 70°C.

Specific examples of the aromatic diol compounds include bisphenol F, bisphenol E, dihydroxybenzene, dihydroxynaphthalene, and dihydroxydiphenyl ether.

Examples of the reactive groups in the hydrocarbon compound having two cyano groups and one reactive group include halogen atoms and nitro groups.
Specific examples of the hydrocarbon compound having two cyano groups and one reactive group include 4-chlorophthalonitrile, 4-bromophthalonitrile, 4-fluorophthalonitrile, 4-nitrophthalonitrile and the like. mentioned.

The imide compound of the present invention has a diamine residue.
Examples of the diamine from which the diamine residue is derived include 3,3′-diaminodiphenylmethane, 3,4′-diaminodiphenylmethane, 4,4′-diaminodiphenylmethane, 3,3′-diaminodiphenyl ether, and 3,4′. -diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 3,3'-diaminodiphenylsulfone, 4,4'-diaminodiphenylsulfone, 1,3-bis (3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene, bis(4-(4-aminophenoxy)phenyl)methane, 2, 2-bis(4-(4-aminophenoxy)phenyl)propane, 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4-bis(2-(4-aminophenyl) )-2-propyl)benzene, 3,3′-diamino-4,4′-dihydroxyphenylmethane, 4,4′-diamino-3,3′-dihydroxyphenylmethane, 3,3′-diamino-4,4 '-dihydroxyphenyl ether, bisaminophenylfluorene, bistoluidinefluorene, 4,4'-bis(4-aminophenoxy)biphenyl, 4,4'-diamino-3,3'-dihydroxyphenyl ether, 3,3'- diamino-4,4'-dihydroxybiphenyl, 4,4'-diamino-2,2'-dihydroxybiphenyl and the like. Among them, 4,4′-diaminodiphenylmethane, 4,4′-diaminodiphenyl ether, 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4 -bis(2-(4-aminophenyl)-2-propyl)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis( 4-Aminophenoxy)benzene is preferred, and 1,3-bis(2-(4-aminophenyl)-2-propyl)benzene, 1,4-bis(2-(2-( 4-aminophenyl)-2-propyl)benzene, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 1,4-bis(4-aminophenoxy)benzene is more preferred.

The imide compound of the present invention preferably has a crosslinkable functional group at its terminal.
The crosslinkable functional group is preferably a functional group capable of reacting with an epoxy group.
Specific examples of the crosslinkable functional groups include amino groups, carboxyl groups, acid anhydride groups, phenolic hydroxyl groups, unsaturated groups, active ester groups, and maleimide groups. Among them, at least one of an acid anhydride group and a phenolic hydroxyl group is more preferable. The imide compound of the present invention may have the crosslinkable functional group at one end or at both ends. When the above-mentioned crosslinkable functional groups are present at both ends, the resulting curable resin composition has a higher glass transition temperature after curing due to the increased crosslink density. On the other hand, when having the crosslinkable functional group at one end, the functional group equivalent increases, and the content of the imide compound of the present invention in the curable resin composition can be increased, so that the resulting curable resin composition can be cured. The product becomes excellent in long-term heat resistance and the like.

The imide compound of the present invention preferably has a structure represented by the following formula (2-1) or the following formula (2-2) as the structure containing the crosslinkable functional group. By having a structure represented by the following formula (2-1) or the following formula (2-2), the imide compound of the present invention is superior in reactivity and compatibility with curable resins such as epoxy resins. Become.

In formulas (2-1) and (2-2), A is the acid dianhydride residue, and B is any organic group. In formula (2-2), Ar is an optionally substituted divalent aromatic group.

In addition, when the imide compound of the present invention has a siloxane skeleton in its structure, it lowers the glass transition temperature after curing and may contaminate the adherend and cause adhesion failure. It is preferably an imide compound that does not have

A preferred upper limit of the molecular weight of the imide compound of the present invention is 8,000. When the molecular weight is 8,000 or less, the obtained cured product of the curable resin composition has excellent heat resistance. A more preferable upper limit of the molecular weight of the imide compound is 7,000.
In particular, the molecular weight of the imide compound of the present invention is preferably 350 or more and 6600 or less when it has the structure represented by the above formula (2-1), and the structure represented by the above formula (2-2) is When it has, it is preferably 370 or more and 7200 or less. A more preferable lower limit of the molecular weight is 380 when having the structure represented by the above formula (2-1). A more preferable lower limit of the molecular weight is 400 when having the structure represented by the above formula (2-2).
In the present specification, the above-mentioned "molecular weight" is the molecular weight obtained from the structural formula for compounds whose molecular structure is specified. It may be expressed using the number average molecular weight. As used herein, the "number average molecular weight" is a value determined by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and converted to polystyrene. Examples of the column used for measuring the polystyrene-equivalent number-average molecular weight by GPC include JAIGEL-2H-A (manufactured by Japan Analytical Industry Co., Ltd.).

Specifically, the imide compound of the present invention is preferably a compound represented by the following formula (3).

In formula (3), R is a structure represented by the above formula (1-1), (1-2), (1-3), (1-4), or (1-5), B is any organic group.

Among the imide compounds of the present invention, a method for producing an imide compound having a structure represented by the formula (2-1) includes, for example, an acid dianhydride from which the acid dianhydride residue is derived, Examples thereof include a method of reacting with a diamine from which the diamine residue is derived.

A specific example of the method for reacting the acid dianhydride and the diamine is shown below.
First, the diamine is dissolved in advance in a solvent (for example, N-methylpyrrolidone, etc.) in which the amic acid compound obtained by the reaction is soluble. The acid dianhydride is added to the obtained solution and reacted to obtain an amic acid compound solution. Then, the solvent is removed by heating, pressure reduction, or the like, and the mixture is further heated at about 200° C. or higher for 1 hour or longer to react the amic acid compound for imidization. By adjusting the molar ratio of the acid dianhydride and the diamine, and imidization conditions, an imide compound having a desired molecular weight and having a structure represented by the above formula (2-1) at both ends can be obtained.
Further, by replacing a part of the acid dianhydride with an acid anhydride represented by the following formula (4), it has a desired molecular weight and is represented by the above formula (2-1) at one end An imide compound having a structure derived from an acid anhydride represented by the following formula (4) at the other end can be obtained. In this case, the acid dianhydride and the acid anhydride represented by the following formula (4) may be added simultaneously or separately.
Furthermore, by replacing part of the diamine with a monoamine represented by the following formula (5), it has a desired number average molecular weight and has a structure represented by the above formula (2-1) at one end. and an imide compound having a monoamine-derived structure represented by the following formula (5) at the other end. In this case, the diamine and the monoamine represented by the following formula (5) may be added simultaneously or separately.

In formula (4), Ar is an optionally substituted divalent aromatic group.

式（５）中、Ａｒは、置換されていてもよい１価の芳香族基であり、Ｒ^１及びＲ^２は、それぞれ独立に、水素原子又は１価の炭化水素基である。

In formula (5), Ar is an optionally substituted monovalent aromatic group, and R ¹ and R ² are each independently a hydrogen atom or a monovalent hydrocarbon group.

Among the imide compounds of the present invention, a method for producing an imide compound having a structure represented by the formula (2-2) includes, for example, an acid dianhydride derived from the acid dianhydride, and the diamine and a method of reacting with a phenolic hydroxyl group-containing monoamine represented by the following formula (6).

In formula (6), Ar is an optionally substituted divalent aromatic group, and R ³ and R ⁴ are each independently a hydrogen atom or a monovalent hydrocarbon group.

A specific example of the method for reacting the above acid dianhydride with the above diamine and the phenolic hydroxyl group-containing monoamine represented by the above formula (6) is shown below.
First, the above diamine and the phenolic hydroxyl group-containing monoamine represented by the above formula (6) are dissolved in advance in a solvent (for example, N-methylpyrrolidone, etc.) in which the amic acid compound obtained by the reaction is soluble. The acid dianhydride is added to the obtained solution and reacted to obtain an amic acid compound solution. Then, the solvent is removed by heating, pressure reduction, or the like, and the mixture is further heated at about 200° C. or higher for 1 hour or longer to react the amic acid compound for imidization. By adjusting the molar ratio of the acid dianhydride and each amine compound and imidization conditions, an imide having a desired molecular weight and having a structure represented by the above formula (2-2) at both ends compounds can be obtained.
Further, by replacing a part of the phenolic hydroxyl group-containing monoamine represented by the above formula (6) with the monoamine represented by the above formula (5), it has a desired number average molecular weight, and one end has the above formula An imide compound having a structure represented by (2-2) and having a structure derived from a monoamine represented by the above formula (5) at the other end can be obtained. In this case, the phenolic hydroxyl group-containing monoamine represented by the above formula (6) and the monoamine represented by the above formula (5) may be added simultaneously or separately.

Examples of the acid anhydride represented by the formula (4) include phthalic anhydride, 3-methylphthalic anhydride, 4-methylphthalic anhydride, 1,2-naphthalic anhydride, and 2,3-naphthalic anhydride. acid anhydride, 1,8-naphthalic anhydride, 2,3-anthracenedicarboxylic anhydride, 4-tert-butyl phthalic anhydride, 4-ethynyl phthalic anhydride, 4-phenylethynyl phthalic anhydride, 4-fluorophthalic anhydride, 4-chlorophthalic anhydride, 4-bromophthalic anhydride, 3,4-dichlorophthalic anhydride and the like.

Monoamines represented by the above formula (5) include, for example, aniline, o-toluidine, m-toluidine, p-toluidine, 2,4-dimethylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 2-tert-butylaniline, 3-tert-butylaniline, 4-tert-butylaniline, 1-naphthylamine, 2-naphthylamine, 1-aminoanthracene, 2-aminoanthracene, 9-aminoanthracene, 1-aminopyrene, 3- Chloroaniline, o-anisidine, m-anisidine, p-anisidine, 1-amino-2-methylnaphthalene, 2,3-dimethylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 3,4-dimethyl aniline, 4-ethylaniline, 4-ethynylaniline, 4-isopropylaniline, 4-(methylthio)aniline, N,N-dimethyl-1,4-phenylenediamine and the like.

Examples of the phenolic hydroxyl group-containing monoamine represented by the above formula (6) include 3-aminophenol, 4-aminophenol, 4-amino-o-cresol, 5-amino-o-cresol, 4-amino-2 ,3-xylenol, 4-amino-2,5-xylenol, 4-amino-2,6-xylenol, 4-amino-1-naphthol, 5-amino-2-naphthol, 6-amino-1-naphthol, 4 -amino-2,6-diphenylphenol and the like. Among them, 4-amino-o-cresol and 5-amino-o-cresol are preferred because of their excellent availability and storage stability and high glass transition temperature.

When produced by the production method described above, the imide compound of the present invention has a structure represented by multiple types of imide compounds having the structure represented by the above formula (2-1) or the above formula (2-2). It is obtained as one contained in a mixture (imide composition) of a plurality of types of imide compounds and respective raw materials. Since the imide composition has an imidization rate of 70% or more, it is possible to obtain a cured product having excellent mechanical strength at high temperatures and long-term heat resistance when used as a curing agent.
A preferable lower limit of the imidization rate of the imide composition is 75%, and a more preferable lower limit is 80%. Although there is no particular upper limit for the imidization rate of the imide composition, the practical upper limit is 98%.
The above-mentioned "imidation rate" is measured by a total reflection measurement method (ATR method) using a Fourier transform infrared spectrophotometer (FT-IR), and is derived from the carbonyl group of amic acid at 1660 cm ^-1 It can be derived from the peak absorbance area in the vicinity by the following formula. Examples of the Fourier transform infrared spectrophotometer include UMA600 (manufactured by Agilent Technologies). The "peak absorbance area of the amic acid compound" in the following formula is obtained by removing the solvent by evaporation or the like without performing the imidization step after reacting the acid dianhydride with each amine compound. is the absorbance area of the amic acid compound obtained.
Imidation rate (%) = 100 × (1-(peak absorbance area after imidization)/(peak absorbance area of amic acid compound))

From the viewpoint of solubility when used as a curing agent in a curable resin composition, the imide composition preferably dissolves in an amount of 3 g or more per 10 g of tetrahydrofuran at 25°C.

The imide composition preferably has a melting point of 200° C. or lower from the viewpoint of handleability when used as a curing agent in a curable resin composition. The melting point of the imide composition is more preferably 190° C. or lower, even more preferably 180° C. or lower.
Moreover, from the viewpoint of storage stability and the like, the melting point of the imide composition is preferably 80° C. or higher.

In the curable resin composition of the present invention, the preferable lower limit of the content of the imide compound is 5 parts by weight, and the preferable upper limit thereof is 85 parts by weight based on the total 100 parts by weight of the curable resin and the imide compound. When the content of the imide compound is within this range, the resulting curable resin composition is superior in flexibility and workability before curing, and in adhesiveness and heat resistance of the cured product. A more preferable lower limit to the content of the imide compound is 8 parts by weight, and a more preferable upper limit is 75 parts by weight.

The curable resin composition of the present invention may contain other curing agents in addition to the above imide compounds in order to further improve the workability before curing, etc., as long as the object of the present invention is not hindered. .
Examples of other curing agents include phenol-based curing agents, thiol-based curing agents, amine-based curing agents, acid anhydride-based curing agents, cyanate-based curing agents, active ester-based curing agents, and the like. Among them, a phenol-based curing agent, an acid anhydride-based curing agent, a cyanate-based curing agent, and an active ester-based curing agent are preferable.

When the curable resin composition of the present invention contains the other curing agent, the upper limit of the content of the other curing agent in 100 parts by weight of the total curing agent is preferably 70 parts by weight, and more preferably 50 parts by weight. A more preferred upper limit is 30 parts by weight.

The curable resin composition of the present invention contains a curable resin.
Examples of the curable resins include epoxy resins, acrylic resins, phenol resins, cyanate resins, isocyanate resins, maleimide resins, benzoxazine resins, silicone resins, fluorine resins, polyimide resins, and phenoxy resins. Especially, it is preferable that the said curable resin contains an epoxy resin. These curable resins may be used alone, or two or more of them may be used in combination.
In addition, the curable resin is preferably in a liquid or semi-solid form at 25° C., more preferably in a liquid form, in order to improve workability such as film processing.

Examples of the epoxy resin include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, bisphenol S type epoxy resin, 2,2'-diallylbisphenol A type epoxy resin, and hydrogenated bisphenol type epoxy resin. , propylene oxide-added bisphenol A type epoxy resin, resorcinol type epoxy resin, biphenyl type epoxy resin, sulfide type epoxy resin, diphenyl ether type epoxy resin, dicyclopentadiene type epoxy resin, naphthalene type epoxy resin, fluorene type epoxy resin, naphthylene ether type epoxy resin, phenol novolak type epoxy resin, ortho-cresol novolak type epoxy resin, dicyclopentadiene novolak type epoxy resin, biphenyl novolak type epoxy resin, naphthalenephenol novolak type epoxy resin, glycidylamine type epoxy resin, alkyl polyol type epoxy resin, Examples include rubber-modified epoxy resins and glycidyl ester compounds. Among them, bisphenol A-type epoxy resin, bisphenol F-type epoxy resin, and bisphenol E-type epoxy resin are used because the viscosity is low and the workability of the obtained curable resin composition before curing can be easily adjusted. At least one selected from the group is preferred.

The curable resin composition of the present invention preferably contains a curing accelerator. By containing the curing accelerator, the curing time can be shortened and the productivity can be improved.

Examples of the curing accelerator include imidazole-based curing accelerators, tertiary amine-based curing accelerators, phosphine-based curing accelerators, photobase generators, and sulfonium salt-based curing accelerators. Among these, imidazole-based curing accelerators and phosphine-based curing accelerators are preferable from the viewpoint of storage stability and curability.
The curing accelerators may be used alone, or two or more of them may be used in combination.

A preferred lower limit for the content of the curing accelerator in the total 100 parts by weight of the curable resin, the imide compound and the curing accelerator is 0.8 parts by weight. When the content of the curing accelerator is 0.8 parts by weight or more, the effect of shortening the curing time is more excellent. A more preferable lower limit for the content of the curing accelerator is 1 part by weight.
From the viewpoint of adhesiveness and the like, the preferred upper limit of the content of the curing accelerator is 10 parts by weight, and the more preferred upper limit is 5 parts by weight.

The curable resin composition of the present invention preferably contains an inorganic filler.
By containing the above-mentioned inorganic filler, the curable resin composition of the present invention has improved moisture absorption reflow resistance, plating resistance, and workability before curing, while maintaining excellent adhesiveness and heat resistance of the cured product. become excellent.

The inorganic filler is preferably at least one of silica and barium sulfate. By containing at least one of silica and barium sulfate as the inorganic filler, the curable resin composition of the present invention is excellent in moisture absorption reflow resistance, plating resistance, and workability before curing. Become.

Examples of inorganic fillers other than silica and barium sulfate include alumina, aluminum nitride, boron nitride, silicon nitride, glass powder, glass frit, glass fiber, carbon fiber, and inorganic ion exchangers.

The above inorganic fillers may be used alone, or two or more of them may be used in combination.

A preferable lower limit of the average particle size of the inorganic filler is 50 nm, and a preferable upper limit thereof is 4 μm. When the average particle size of the inorganic filler is within this range, the resulting curable resin composition is superior in coatability and workability. A more preferable lower limit of the average particle size of the inorganic filler is 100 nm, and a more preferable upper limit thereof is 3 μm.

The content of the inorganic filler has a preferable lower limit of 10 parts by weight and a preferable upper limit of 150 parts by weight with respect to a total of 100 parts by weight of the curable resin and the imide compound. When the content of the inorganic filler is within this range, the resulting curable resin composition is excellent in moisture absorption reflow resistance, plating resistance, and workability before curing. A more preferable lower limit for the content of the inorganic filler is 20 parts by weight.

The curable resin composition of the present invention may contain a fluidity modifier for the purpose of improving wettability to an adherend in a short time and shape retention.
Examples of the flow control agent include fumed silica such as Aerosil and layered silicate.
The flow modifiers may be used alone, or two or more of them may be used in combination.
Moreover, as the fluidity control agent, one having an average particle size of less than 100 nm is preferably used.

The content of the flow control agent has a preferable lower limit of 0.1 parts by weight and a preferable upper limit of 50 parts by weight with respect to a total of 100 parts by weight of the curable resin and the imide compound. When the content of the flow control agent is within this range, the effect of improving the wettability to the adherend in a short time and the shape retention property, etc., is excellent. A more preferable lower limit of the content of the flow control agent is 0.5 parts by weight, and a more preferable upper limit thereof is 30 parts by weight.

The curable resin composition of the present invention may contain an organic filler for the purpose of relaxing stress, imparting toughness, and the like.
Examples of the organic filler include silicone rubber particles, acrylic rubber particles, urethane rubber particles, polyamide particles, polyamideimide particles, polyimide particles, benzoguanamine particles, and core-shell particles thereof. Among them, polyamide particles, polyamideimide particles, and polyimide particles are preferred.
The above organic fillers may be used alone, or two or more of them may be used in combination.

A preferable upper limit of the content of the organic filler is 300 parts by weight with respect to a total of 100 parts by weight of the curable resin and the imide compound. When the content of the organic filler is within this range, the resulting cured product of the curable resin composition is excellent in toughness and the like while maintaining excellent adhesiveness and the like. A more preferable upper limit of the content of the organic filler is 200 parts by weight.

The curable resin composition of the invention may contain a flame retardant.
Examples of the flame retardant include boehmite-type aluminum hydroxide, aluminum hydroxide, metal hydrates such as magnesium hydroxide, halogen-based compounds, phosphorus-based compounds, and nitrogen compounds. Among them, boehmite-type aluminum hydroxide is preferable.
The flame retardants may be used alone, or two or more of them may be used in combination.

The content of the flame retardant has a preferable lower limit of 5 parts by weight and a preferable upper limit of 200 parts by weight with respect to a total of 100 parts by weight of the curable resin and the imide compound. When the content of the flame retardant is within this range, the resulting cured product of the curable resin composition has excellent flame retardancy while maintaining excellent adhesion and the like. A more preferable lower limit to the content of the flame retardant is 10 parts by weight, and a more preferable upper limit is 150 parts by weight.

The curable resin composition of the present invention may contain a polymer compound as long as the object of the present invention is not impaired. The polymer compound serves as a film-forming component.

The polymer compound may have a reactive functional group.
Examples of the reactive functional groups include amino groups, urethane groups, imide groups, hydroxyl groups, carboxyl groups, and epoxy groups.

Moreover, the polymer compound may form a phase-separated structure in the cured product, or may not form a phase-separated structure. When the polymer compound does not form a phase separation structure in the cured product, the polymer compound has excellent mechanical strength at high temperatures, long-term heat resistance, and moisture resistance. Polymer compounds having epoxy groups are preferred.

The curable resin composition of the present invention may contain a solvent from the viewpoint of coatability and the like.
As the solvent, a nonpolar solvent having a boiling point of 120° C. or lower or an aprotic polar solvent having a boiling point of 120° C. or lower is preferable from the viewpoint of coatability, storage stability, and the like.
Examples of the nonpolar solvent having a boiling point of 120° C. or lower or the aprotic polar solvent having a boiling point of 120° C. or lower include ketone solvents, ester solvents, hydrocarbon solvents, halogen solvents, ether solvents, and nitrogen-containing solvents. system solvents and the like.
Examples of the ketone solvent include acetone, methyl ethyl ketone, and methyl isobutyl ketone.
Examples of the ester solvent include methyl acetate, ethyl acetate, and isobutyl acetate.
Examples of the hydrocarbon solvent include benzene, toluene, normal hexane, isohexane, cyclohexane, methylcyclohexane, normal heptane and the like.
Examples of the halogen-based solvent include dichloromethane, chloroform, and trichlorethylene.
Examples of the ether solvent include diethyl ether, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane and the like.
Examples of the nitrogen-containing solvent include acetonitrile.
Among them, from the viewpoint of handleability, solubility of imide compounds, etc., a group consisting of ketone solvents with a boiling point of 60°C or higher, ester solvents with a boiling point of 60°C or higher, and ether solvents with a boiling point of 60°C or higher. At least one more selected is preferable. Examples of such solvents include methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, isobutyl acetate, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran and the like.
The "boiling point" means a value measured under conditions of 101 kPa, or a value converted to 101 kPa using a boiling point conversion chart or the like.

The preferable lower limit of the content of the solvent in 100 parts by weight of the curable resin composition of the present invention is 20 parts by weight, and the preferable upper limit is 90 parts by weight. When the content of the solvent is within this range, the curable resin composition of the present invention is superior in coatability and the like. A more preferable lower limit for the content of the solvent is 30 parts by weight, and a more preferable upper limit is 80 parts by weight.

The curable resin composition of the present invention may contain a reactive diluent as long as the object of the present invention is not impaired.
From the viewpoint of adhesion reliability, the reactive diluent is preferably a reactive diluent having two or more reactive functional groups in one molecule.

The curable resin composition of the present invention may further contain additives such as coupling agents, dispersants, storage stabilizers, anti-bleeding agents, fluxing agents and leveling agents.

As a method for producing the curable resin composition of the present invention, for example, using a mixer such as a homodisper, a universal mixer, a Banbury mixer, or a kneader, a curable resin, an imide compound, and, if necessary, are added. A method of mixing with a solvent or the like can be mentioned.

A curable resin composition film comprising the curable resin composition of the present invention can be obtained by applying the curable resin composition of the present invention onto a substrate film and drying the curable resin composition. A cured product can be obtained by curing the product film.

The curable resin composition of the present invention preferably has a glass transition temperature of 100°C or higher and lower than 250°C. When the glass transition temperature before curing is within this range, the curable resin composition of the present invention provides a cured product with excellent mechanical strength and long-term heat resistance. A more preferable lower limit of the glass transition temperature of the cured product is 120°C, and a more preferable upper limit thereof is 220°C.
The cured product for measuring the glass transition temperature can be obtained by heating the curable resin composition film having a thickness of 400 μm at 190° C. for 1 hour.

The curable resin composition of the present invention preferably has an initial adhesive strength of 3.4 N/cm or more to polyimide as a cured product. Since the cured product has an initial adhesive strength of 3.4 N/cm or more to polyimide, the curable resin composition of the present invention can be suitably used as a coverlay adhesive for flexible printed circuit boards. The initial adhesive strength of the cured product to polyimide is more preferably 5 N/cm or more, still more preferably 6 N/cm or more.
In addition, the initial adhesive strength to the polyimide is measured as the peel strength when a test piece cut into a width of 1 cm is subjected to T-shaped peeling at 25 ° C. and a peeling speed of 20 mm / min using a tensile tester. be able to. As the test piece, those obtained by laminating polyimide films having a thickness of 50 μm on both sides of a curable resin composition film having a thickness of 20 μm and heating at 190° C. for 1 hour are used. , means the value measured within 24 hours after the preparation of the test piece. The curable resin composition film can be obtained by applying the curable resin composition onto a base film and drying it. Kapton 200H (manufactured by DuPont Toray Co., Ltd.; surface roughness 0.03 to 0.07 μm) can be used as the polyimide. Examples of the tensile tester include UCT-500 (manufactured by ORIENTEC).

In the curable resin composition of the present invention, the adhesive strength of the cured product to polyimide after storage at 200° C. for 100 hours is preferably 0.8 times or more the initial adhesive strength. The curable resin composition of the present invention has a heat resistance such as in-vehicle use because the adhesive strength to polyimide of the cured product after storage at 200 ° C. for 100 hours is at least 0.8 times the initial adhesive strength. It can be suitably used for adhesives. The adhesion of the cured product to polyimide after being stored at 200° C. for 100 hours is more preferably 0.85 times or more, still more preferably 0.9 times or more, of the initial adhesion.
The adhesive strength of the cured product to polyimide after storage at 200 ° C. for 100 hours is up to 25 ° C. after storing a test piece prepared in the same manner as the initial adhesive strength measurement method at 200 ° C. for 100 hours. It means a value measured in the same manner as the above-mentioned initial adhesive strength within 24 hours after standing to cool.

The curable resin composition of the present invention can be used in a wide range of applications, and is particularly suitable for electronic material applications that require high heat resistance. For example, it can be used as a die attach agent for aviation and automotive electric control unit (ECU) applications, and for power device applications using SiC and GaN. Also, for example, adhesives for power overlay packages, adhesives for printed wiring boards, adhesives for coverlay films of flexible printed wiring boards, copper-clad laminates, adhesives for semiconductor bonding, interlayer insulating films, prepregs, and LED sealing It can also be used as a blocking agent, an adhesive for structural materials, and the like. Among others, it is preferably used for adhesives. An adhesive containing the curable resin composition of the present invention is also one aspect of the present invention.

The curable resin film can be suitably used as an adhesive film. An adhesive film using the curable resin composition of the present invention is also one aspect of the present invention.
A coverlay film having a substrate film and a layer formed of a cured product of the curable resin composition of the present invention provided on the substrate film is also one aspect of the present invention.
Furthermore, a flexible copper-clad laminate having a substrate film, a layer formed of a cured product of the curable resin composition of the present invention provided on the substrate film, and a copper foil is also one of the present invention. be.

ADVANTAGE OF THE INVENTION According to this invention, the curable resin composition which is excellent in flexibility and processability before hardening, and is excellent in adhesiveness and heat resistance after hardening can be provided. Further, according to the present invention, an imide compound that can be used in the curable resin composition, and an adhesive, an adhesive film, a coverlay film, and a flexible copper clad laminate using the curable resin composition boards can be provided.

EXAMPLES The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to these Examples.

(Synthesis example 1)
(Preparation of acid dianhydride represented by formula (7))
60 parts by weight of bisphenol F (melting point 162° C.) and 104 parts by weight of 4-nitrophthalonitrile are dissolved in 800 parts by weight of dimethyl sulfoxide together with 83 parts by weight of potassium carbonate, and stirred at room temperature for 18 hours to react to give a tetracyano compound. got Next, the obtained tetracyano compound was dissolved in a mixed solvent of water and methanol together with 220 parts by weight of potassium hydroxide, and the solution was hydrolyzed by heating under reflux conditions for 1 week to obtain a tetracarboxylic acid. Thereafter, the obtained tetracarboxylic acid was heated at 200° C. for 2 hours under vacuum conditions for dehydration condensation to obtain an acid dianhydride represented by the following formula (7).
The structure of the acid dianhydride represented by the following formula (7) was confirmed by ¹ H-NMR, GPC, and FT-IR analysis.

(Preparation of imide composition A)
29.2 parts by weight of 1,3-bis(3-aminophenoxy)benzene (manufactured by Mitsui Chemicals Fine Co., Ltd., "APB-N") and 400 parts by weight of N-methylpyrrolidone (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., "NMP") dissolved in parts. 96.1 parts by weight of the acid dianhydride represented by the above formula (7) was added to the resulting solution, and the mixture was stirred at 25°C for 2 hours for reaction to obtain an amic acid compound solution. After removing N-methylpyrrolidone from the obtained amic acid compound solution under reduced pressure, the solution was heated at 300° C. for 2 hours to obtain an imide composition A (imidization rate: 91%).
¹ H-NMR, GPC, and FT-IR analysis revealed that the imide composition A was an imide compound having a structure represented by the above formula (2-1) (A represented by the following formula (8) It was confirmed that the acid dianhydride residue and B contained an organic group (diamine residue) represented by the following formula (9). Also, the number average molecular weight of the imide compound having the structure represented by the formula (2-1) was 3,950. Furthermore, it was confirmed that the imide composition A contained an imide compound represented by the following formula (10).

In formula (8), * is a binding position.

In formula (9), * is a binding position.

(Synthesis example 2)
(Preparation of acid dianhydride represented by formula (11))
Except that 72 parts by weight of bisphenol E (melting point: 125°C) was used instead of 60 parts by weight of bisphenol F (melting point: 162°C). )” to obtain an acid dianhydride represented by the following formula (11).
The structure of the acid dianhydride represented by formula (11) below was confirmed by ¹ H-NMR, GPC, and FT-IR analysis.

(Preparation of imide composition B)
Except for using 108 parts by weight of the acid dianhydride represented by the above formula (11) instead of 96.1 parts by weight of the acid dianhydride represented by the above formula (7), Synthesis Example 1 "( Preparation of imide composition A)” to obtain imide composition B (imidization rate: 93%).
¹ H-NMR, GPC, and FT-IR analysis revealed that the imide composition B was an imide compound having a structure represented by the above formula (2-1) (A represented by the following formula (12) It was confirmed that the acid dianhydride residue and B contained the organic group (diamine residue) represented by the above formula (9). Also, the number average molecular weight of the imide compound having the structure represented by the formula (2-1) was 4,500. Furthermore, it was confirmed that the imide composition B contained an imide compound represented by the following formula (13).

In formula (12), * is a binding position.

(Synthesis Example 3)
(Preparation of acid dianhydride represented by formula (14))
Except for using 33 parts by weight of resorcinol (melting point: 110°C) instead of 60 parts by weight of bisphenol F (melting point: 162°C), Synthesis Example 1 “(Preparation of acid dianhydride represented by formula (7)) ” to obtain an acid dianhydride represented by the following formula (14).
The structure of the acid dianhydride represented by formula (14) below was confirmed by ¹ H-NMR, GPC, and FT-IR analysis.

(Preparation of imide composition C)
Except for using 80 parts by weight of the acid dianhydride represented by the above formula (14) instead of 96.1 parts by weight of the acid dianhydride represented by the above formula (7), Synthesis Example 1 "( Preparation of imide composition A)” to obtain imide composition C (imidization rate: 89%).
¹ H-NMR, GPC, and FT-IR analysis revealed that the imide composition C was an imide compound having a structure represented by the above formula (2-1) (A represented by the following formula (15) It was confirmed that the acid dianhydride residue and B contained the organic group (diamine residue) represented by the above formula (9). Also, the number average molecular weight of the imide compound having the structure represented by the formula (2-1) was 3,480. Furthermore, it was confirmed that the imide composition C contained an imide compound represented by the following formula (16).

In formula (15), * is a binding position.

(Synthesis Example 4)
(Preparation of acid dianhydride represented by formula (17))
Except that 68.5 parts by weight of bisphenol A (melting point 158 ° C.) was used instead of 60 parts by weight of bisphenol F (melting point 162 ° C.), "(acid dianhydride represented by formula (7) Preparation)” to obtain an acid dianhydride represented by the following formula (17).
The structure of the acid dianhydride represented by formula (17) below was confirmed by ¹ H-NMR, GPC, and FT-IR analysis.

(Preparation of imide composition D)
Except for using 104 parts by weight of the acid dianhydride represented by the above formula (17) instead of 96.1 parts by weight of the acid dianhydride represented by the above formula (7), Synthesis Example 1 "( Preparation of imide composition A)” to obtain imide composition D (imidization rate: 93%).
¹ H-NMR, GPC, and FT-IR analysis revealed that the imide composition D was an acid dianhydride in which the portion corresponding to A in the above formula (2-1) was represented by the following formula (18). It was confirmed to contain an imide compound having a structure in which the portion corresponding to B is an organic group (diamine residue) represented by the above formula (9). The imide compound had a number average molecular weight of 4,720. Furthermore, it was confirmed that the imide composition D contained an imide compound represented by the following formula (19).

In formula (18), * is a binding position.

(Examples 1 to 6, Comparative Examples 1 to 3)
According to the compounding ratio shown in Table 1, each material was stirred and mixed to prepare curable resin compositions of Examples 1 to 6 and Comparative Examples 1 to 3.
A curable resin composition film was obtained by coating each obtained curable resin composition on a substrate PET film so as to have a thickness of about 20 μm, followed by drying.
The substrate PET film was peeled off from each of the obtained curable resin composition films and laminated using a laminator to produce a 400 μm thick curable resin composition film laminate. Each curable resin composition film thus obtained was cured by heating at 190° C. for 1 hour to prepare a cured product.
The obtained curable resin composition film laminate was measured using a differential scanning calorimeter (manufactured by Hitachi High-Tech Science, "DSC7000 series") at a temperature increase rate of 10 ° C./min. The glass transition temperature was obtained from the inflection point of the accompanying endothermic peak. Table 1 shows the results.
In addition, the obtained cured product was measured using a thermogravimetry device ("TG/DTA6200" manufactured by Hitachi High-Tech Science Co., Ltd.) at a temperature range of 30 ° C. to 500 ° C. and a temperature increase of 10 ° C./min. % weight loss temperature was measured. Table 1 shows the results.

<Evaluation>
Each curable resin composition and each curable resin composition film obtained in Examples and Comparative Examples were evaluated as follows. Table 1 shows the results.

(Flexibility)
Each curable resin composition film obtained in Examples and Comparative Examples was subjected to a 5 mm diameter winding test in which the curable resin composition film was wound around a cylinder having a diameter of 5 mm at 25° C., and cracking and chipping of the curable resin composition film were confirmed. . Further, a 180-degree bending test was conducted by bending the obtained adhesive film 180 degrees, and cracks and chips in the curable resin composition film were confirmed.
"○" indicates that there were no cracks or chips in both the 5 mm diameter winding test and the 180 degree bending test. Flexibility was evaluated as “Δ” when there was a crack or chipping in both tests, and “x” when there was cracking or chipping in both tests.

(workability)
For each curable resin composition film obtained in Examples and Comparative Examples, punching was performed using a Thomson blade at 25° C., and the state of the fracture surface and the presence or absence of falling powder were checked.
bottom. "○" when the fracture surface was smooth and no powder fell off, "△" when the fracture surface was not smooth but no powder fell off, and "△" when the fracture surface was not smooth and powder fell off. The workability was evaluated as "x".

(Glass transition temperature of cured product)
The substrate PET film was peeled off from each curable resin composition film obtained in Examples and Comparative Examples, laminated using a laminator, and then cured by heating at 190 ° C. for 1 hour to cure to a thickness of 400 μm. made things. The resulting cured product was measured using a dynamic viscoelasticity measuring device (manufactured by A&D Co., Ltd., "Leovibron DDV-25GP") at a temperature increase rate of 10 ° C./min, a frequency of 10 Hz, and a distance between chucks of 24 mm to 0 ° C. The peak temperature of the tan δ curve obtained when the temperature was raised from to 300° C. was determined as the glass transition temperature.

(initial adhesiveness)
The base PET film was peeled off from each curable resin composition film obtained in Examples and Comparative Examples, and a polyimide film having a thickness of 50 μm (Toray · “Kapton 200H” manufactured by DuPont) was pasted together. After hot pressing was performed under the conditions of 190° C., 3 MPa, and 1 hour to cure the adhesive layer, a test piece was obtained by cutting into a width of 1 cm. A test piece within 24 hours after preparation was subjected to T-shaped peeling at a peeling speed of 20 mm / min at 25 ° C. with a tensile tester ("UCT-500" manufactured by ORIENTEC) to measure the peel strength. The peel strength was defined as the initial adhesive strength.
"○" when the initial adhesive strength was 6.0 N / cm or more, "△" when it was 3.4 N / cm or more and less than 6.0 N / cm, when it was less than 3.4 N / cm was evaluated as "x" and the initial adhesiveness was evaluated.

(Long-term heat resistance)
A 20 μm-thick polyimide film (manufactured by Toray DuPont, “Kapton V”) was laminated on both sides of each curable resin composition film obtained in Examples and Comparative Examples, and heated at 190° C. for 1 hour. After curing, heat treatment was performed at 175° C. for 1000 hours. After the laminate of the cured product of the curable resin composition after heat treatment and the polyimide film is laid along a cylinder with a diameter of 5 mm or 3 mm at room temperature in a semicircular shape, the laminate of the curable resin composition film and the polyimide film was visually observed.
"O" indicates that no cracks or cracks were observed when the laminate was semicircularly aligned with a 3 mm cylinder, and no cracks or cracks were observed when the laminate was semicircularly aligned with a 5 mm cylinder. However, "△" indicates that cracks or cracks were observed when the sample was placed along a 3mm cylinder in a semicircular shape, and "X" indicates that cracks or cracks were observed when the sample was placed along a 5mm cylinder in a semicircular shape. Long-term heat resistance was evaluated.

ADVANTAGE OF THE INVENTION According to this invention, the curable resin composition which is excellent in flexibility and processability before hardening, and is excellent in adhesiveness and heat resistance after hardening can be provided. Further, according to the present invention, an imide compound that can be used in the curable resin composition, and an adhesive, an adhesive film, a coverlay film, and a flexible copper clad laminate using the curable resin composition boards can be provided.

Claims (8)

A curable resin composition containing an epoxy resin and an imide compound,
The imide compound is a compound represented by the following formula (3),
The content of the epoxy resin in the curable resin composition (excluding the solvent) is 14.6% by weight or more,
A curable resin composition having a glass transition temperature of less than 25°C before curing and a 5% weight loss temperature of 320°C or higher.

In formula (3), R is a structure represented by the following formula (1-1), (1-2), (1-3), (1-4), or (1-5), B is any organic group.

All or part of the hydrogen atoms in the aromatic rings in formulas (1-1) to (1-5) may be substituted. The curable resin composition according to claim 1, wherein the imide compound has a molecular weight of 8,000 or less. 3. The curable resin composition according to claim 1, wherein said epoxy resin contains at least one selected from the group consisting of bisphenol A type epoxy resin, bisphenol F type epoxy resin, and bisphenol E type epoxy resin. The curable resin composition according to claim 1, 2 or 3, wherein the imide compound has an acid dianhydride residue containing a structure derived from an aromatic diol compound having a melting point of 156°C or less, and a diamine residue. . An adhesive comprising the curable resin composition according to claim 1, 2, 3 or 4 . An adhesive film using the curable resin composition according to claim 1, 2, 3 or 4 . A coverlay film comprising a substrate film and a layer comprising a cured product of the curable resin composition according to claim 1, 2, 3 or 4 provided on the substrate film. A flexible copper-clad laminate comprising a substrate film, a layer comprising a cured product of the curable resin composition according to claim 1, provided on the substrate film, and a copper foil.