CN110691805A

CN110691805A - Curable resin composition, cured product, adhesive film, cover lay film, and printed wiring board

Info

Publication number: CN110691805A
Application number: CN201880036020.0A
Authority: CN
Inventors: 胁冈纱香; 竹田幸平; 新城隆; 大当悠太
Original assignee: Sekisui Chemical Co Ltd
Current assignee: Sekisui Chemical Co Ltd
Priority date: 2017-05-31
Filing date: 2018-05-16
Publication date: 2020-01-14
Also published as: KR20200013649A

Abstract

The purpose of the present invention is to provide a curable resin composition which has excellent flow characteristics before curing and excellent adhesion, heat resistance and bending resistance after curing. It is another object of the present invention to provide a cured product of the curable resin composition, and an adhesive, an adhesive film, a coverlay film and a printed wiring board each using the curable resin composition. The present invention is a curable resin composition containing a thermosetting resin, a thermoplastic resin, and an imide oligomer having a reactive functional group capable of reacting with the thermosetting resin.

Description

Curable resin composition, cured product, adhesive film, cover lay film, and printed wiring board

Technical Field

The present invention relates to a curable resin composition having excellent flow characteristics before curing and excellent adhesiveness, heat resistance and bending resistance after curing. The present invention also relates to a cured product of the curable resin composition, and an adhesive, an adhesive film, a coverlay film, and a printed wiring board each using the curable resin composition.

The present invention also relates to a curable resin composition which can provide a cured product having excellent storage stability, low linear expansibility, adhesiveness, and long-term heat resistance. The present invention also relates to a cured product of the curable resin composition, and an adhesive film each using the curable resin composition.

The present invention also relates to a curable resin composition which is excellent in flexibility and processability before curing and excellent in adhesiveness and heat resistance after curing. The present invention also relates to a cured product of the curable resin composition, and an adhesive film each using the curable resin composition.

Background

A flexible printed circuit board (FPC) generally has a structure in which a copper foil or the like is bonded to one surface or both surfaces of an insulating film such as a polyimide film via an adhesive layer. An adhesive used for an adhesive layer of a flexible printed wiring board is required to have excellent flow characteristics capable of satisfying both sufficient filling properties (uneven filling properties) and leaching resistance during thermocompression bonding. As such an adhesive, for example, patent documents 1 to 3 disclose a curable resin composition containing a thermosetting component such as an epoxy resin; and a flexible component such as an acrylic resin, a thermoplastic resin such as polyamide or polyester, or an acrylonitrile butadiene rubber.

On the other hand, as the applications in vehicle-mounted applications and the like have expanded in recent years, long-term heat resistance is required for adhesives. However, adhesives using the curable resin compositions disclosed in patent documents 1 to 3 have insufficient heat resistance.

As an adhesive excellent in heat resistance, patent document 4 discloses an adhesive containing a soluble polyester, a phenoxy resin, and an imide siloxane oligomer. However, the adhesive disclosed in patent document 4 has poor flow characteristics, and it is difficult to achieve both filling properties and leaching resistance.

Curable resins such as epoxy resins having low shrinkage and excellent adhesion, insulation properties and chemical resistance are used in various industrial products. In particular, in electronic equipment applications, curable resin compositions that can obtain good results in a reflow test for short-term heat resistance and a cooling-heating cycle test for repeated heat resistance are often used.

In recent years, attention has been paid to an Electric Control Unit (ECU) for a vehicle, a power device using SiC or GaN, and the like, but a curable resin composition used for these applications is required to have not only short-term heat resistance and repeated heat resistance but also heat resistance when exposed to high temperatures continuously and for a long period of time (long-term heat resistance).

Patent document 5 discloses that a specific imide oligomer having a phenolic hydroxyl group or an amino group at a terminal is used as a curing agent, thereby improving low thermal expansion properties, heat resistance, and the like of a curable resin composition. However, the curable resin composition disclosed in patent document 5 has problems that it is poor in storage stability, or a cured product thereof is excellent in thermal decomposition resistance but poor in long-term heat resistance.

Further, patent document 6 discloses a curable resin composition using an imide oligomer curing agent having an acid anhydride structure at both ends. However, the curable resin composition disclosed in patent document 6 has a problem of poor adhesiveness, or poor long-term heat resistance or low linear expansion of a cured product.

For example, patent documents 6 and 7 disclose a curable resin composition containing an epoxy resin and an imide oligomer as a curing agent. However, since the imide oligomer generally has a hard and brittle property at room temperature, the curable resin compositions disclosed in patent documents 6 and 7 have problems in flexibility, processability, flowability and the like at room temperature.

As a curable resin composition having improved processability, fluidity and the like, patent document 5 discloses a curable resin composition containing a liquid epoxy resin and an imide oligomer having a specific reactive functional group. However, even the curable resin composition disclosed in patent document 5 cannot be said to have sufficient fluidity, and when the content of the liquid epoxy resin is increased to further improve fluidity, there is a problem that heat resistance and adhesiveness are reduced.

Further, patent document 8 discloses a method of improving flexibility of a curable resin composition before curing by dispersing a nitrile rubber component in a resin mixture containing an imide oligomer having a specific reactive functional group, an epoxy resin, and a bismaleimide-triazine resin. However, the method disclosed in patent document 8 has a problem that the heat resistance of the cured product is deteriorated by the nitrile rubber component.

Documents of the prior art

Patent document

Patent document 1: japanese patent laid-open No. 2006 and 232984

Patent document 2: japanese patent laid-open publication No. 2009-167396

Patent document 3: japanese laid-open patent publication No. 2008-308686

Patent document 4: japanese laid-open patent publication No. 5-306386

Patent document 5: japanese laid-open patent publication No. 2007-91799

Patent document 6: japanese laid-open patent publication No. 61-270852

Patent document 7: japanese Kokai publication Hei-2004-502859

Patent document 8: japanese laid-open patent publication No. 7-224269

Disclosure of Invention

Problems to be solved by the invention

The purpose of the present invention is to provide a curable resin composition which has excellent flow characteristics before curing and excellent adhesion, heat resistance and bending resistance after curing. It is another object of the present invention to provide a cured product of the curable resin composition, and an adhesive, an adhesive film, a coverlay film and a printed wiring board each using the curable resin composition.

Further, an object of the present invention is to provide a curable resin composition which can give a cured product having excellent storage stability and excellent low linear expansibility, adhesiveness and long-term heat resistance. Another object of the present invention is to provide a cured product of the curable resin composition, and an adhesive film each using the curable resin composition.

Further, an object of the present invention is to provide a curable resin composition which is excellent in flexibility and processability before curing and excellent in adhesiveness and heat resistance after curing. Another object of the present invention is to provide a cured product of the curable resin composition, and an adhesive film each using the curable resin composition.

Means for solving the problems

The present invention 1 is a curable resin composition containing a thermosetting resin, a thermoplastic resin, and an imide oligomer having a reactive functional group capable of reacting with the thermosetting resin.

The present invention 1 is described in detail below.

The present inventors studied: in a curable resin composition containing a thermosetting resin, a thermoplastic resin, and an imide oligomer, an imide oligomer having a reactive functional group capable of reacting with the thermosetting resin is used as the imide oligomer. As a result, they found that: the present inventors have completed the present invention 1 by obtaining a curable resin composition which is excellent in flow characteristics before curing and excellent in adhesiveness, heat resistance and bending resistance after curing.

The curable resin composition of the present invention 1 contains a thermosetting resin.

As the thermosetting resin, an epoxy resin is suitably used.

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' -diallylbisphenol A type epoxy resin, 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, naphthalene ether type epoxy resin, phenol novolac type epoxy resin, o-cresol novolac type epoxy resin, dicyclopentadiene novolac type epoxy resin, biphenol aldehyde type epoxy resin, naphthol novolac type epoxy resin, glycidyl amine type epoxy resin, alkyl polyhydric alcohol type epoxy resin, rubber modified epoxy resin, fluorene type epoxy resin, Glycidyl ester compounds, and the like. Among them, epoxy resins that are liquid at room temperature, such as bisphenol a type epoxy resin, bisphenol F type epoxy resin, bisphenol E type epoxy resin, and resorcinol type epoxy resin, are preferable from the viewpoint of low viscosity and easy adjustment of processability of the obtained curable resin composition at room temperature. The epoxy resins may be used alone or in combination of two or more.

The lower limit of the number average molecular weight of the thermosetting resin is preferably 90, and the upper limit thereof is preferably 3000. When the number average molecular weight of the thermosetting resin is in this range, the obtained curable resin composition has more excellent adhesiveness and heat resistance. The lower limit of the number average molecular weight of the thermosetting resin is more preferably 100, and the upper limit is more preferably 2500.

In the present specification, the "number average molecular weight" is a value measured by Gel Permeation Chromatography (GPC) and obtained in terms of polystyrene. Examples of the column used for measuring the number average molecular weight in terms of polystyrene by GPC include JAIGEL-2H-A (manufactured by JAN ANALYSIS INDUSTRIAL CO., LTD.).

The lower limit of the content of the thermosetting resin in 100 parts by weight of the total of the thermosetting resin, the thermoplastic resin, and the imide oligomer is preferably 10 parts by weight, and the upper limit is preferably 90 parts by weight. When the content of the thermosetting resin is 10 parts by weight or more, the obtained curable resin composition has more excellent adhesiveness and heat resistance. By setting the content of the thermosetting resin to 90 parts by weight or less, the flow characteristics of the obtained curable resin composition become more excellent. The lower limit of the content of the thermosetting resin is more preferably 20 parts by weight, and the upper limit is more preferably 80 parts by weight.

The curable resin composition of the present invention 1 contains a thermoplastic resin.

By using the thermoplastic resin, the curable resin composition of the present invention 1 has excellent flow characteristics, is easy to satisfy both filling properties and leaching resistance during thermocompression bonding, and has excellent bending resistance after curing.

Examples of the thermoplastic resin include phenoxy resins, polyamides, acrylic resins, and polyesters. Among them, phenoxy resins and polyamides are preferable from the viewpoint of heat resistance, and phenoxy resins are more preferable from the viewpoint of leaching resistance and handling property at the time of thermocompression bonding.

Examples of the phenoxy resin include bisphenol a type phenoxy resin, bisphenol F type phenoxy resin, bisphenol E type phenoxy resin, bisphenol a-bisphenol F type phenoxy resin, acetophenone-biphenyl type phenoxy resin, bisphenol S type phenoxy resin, phosphorus-containing phenoxy resin, trimethylcyclohexane skeleton phenoxy resin, bisphenol fluorene skeleton phenoxy resin, and the like. Among them, bisphenol a type phenoxy resin, bisphenol F type phenoxy resin, and bisphenol a-bisphenol F type phenoxy resin are preferable.

The lower limit of the weight average molecular weight of the thermoplastic resin is preferably 3000, and the upper limit is preferably 20 ten thousand. When the weight average molecular weight of the thermoplastic resin is in this range, the flow characteristics and the bending resistance after curing of the curable resin composition obtained are further improved. The weight average molecular weight of the thermoplastic resin has a more preferable lower limit of 5000, a more preferable upper limit of 15 ten thousand, and a further more preferable upper limit of 10 ten thousand.

When the thermoplastic resin is used for applications requiring a higher level of bending resistance, the preferred lower limit of the weight average molecular weight of the thermoplastic resin is 1 ten thousand.

In the present specification, the "weight average molecular weight" is a value obtained by measuring by Gel Permeation Chromatography (GPC) using tetrahydrofuran as a solvent and converting into polystyrene. Examples of the column used for measuring the weight average molecular weight in terms of polystyrene by GPC include JAIGEL-2H-A (manufactured by JAN ANALYSIS INDUSTRIAL CO., LTD.).

The lower limit of the content of the thermoplastic resin in 100 parts by weight of the total of the thermosetting resin, the thermoplastic resin, and the imide oligomer is preferably 1 part by weight, and the upper limit is preferably 60 parts by weight. By setting the content of the thermoplastic resin to 1 part by weight or more, the flow characteristics and the bending resistance after curing of the obtained curable resin composition become more excellent. When the content of the thermoplastic resin is 60 parts by weight or less, the obtained curable resin composition has more excellent adhesiveness and heat resistance. The lower limit of the content of the thermosetting resin is more preferably 3 parts by weight, and the upper limit is more preferably 50 parts by weight.

The curable resin composition of the present invention 1 contains an imide oligomer.

The imide oligomer has a reactive functional group capable of reacting with the thermosetting resin. By using an imide oligomer having a reactive functional group capable of reacting with the thermosetting resin, the curable resin composition of the present invention 1 has excellent adhesiveness and heat resistance after curing while maintaining the effect of achieving both filling property and leaching resistance during thermocompression bonding and bending resistance after curing.

The reactive functional group of the imide oligomer varies depending on the kind of the thermosetting resin used, but when an epoxy resin is used as the thermosetting resin, an acid anhydride group and/or a phenolic hydroxyl group is preferable.

The imide oligomer preferably has the reactive functional group at a terminal of a main chain, and more preferably has the reactive functional groups at both terminals.

Examples of the method for producing the imide oligomer having an acid anhydride group as the reactive functional group include a method in which an acid dianhydride represented by the following formula (1) is reacted with a diamine represented by the following formula (2).

Further, as a method for producing an imide oligomer having a phenolic hydroxyl group as the reactive functional group, for example, a method of reacting an acid dianhydride represented by the following formula (1) with a phenolic hydroxyl group-containing monoamine represented by the following formula (3) may be mentioned. Further, there may be mentioned a method in which an acid dianhydride represented by the following formula (1) is reacted with a diamine represented by the following formula (2), and then a phenol hydroxyl group-containing monoamine represented by the following formula (3) is further reacted.

[ solution 1]

In the formula (1), A is a 4-valent group represented by the following formula (4-1) or the following formula (4-2).

[ solution 2]

In the formula (2), B is a 2-valent group represented by the following formula (5-1) or the following formula (5-2), R¹～R⁴Each independently a hydrogen atom or a 1-valent hydrocarbon group.

[ solution 3]

In the formula (3), Ar is an optionally substituted 2-valent aromatic group, R⁵And R⁶Each independently a hydrogen atom or a 1-valent hydrocarbon group.

[ solution 4]

In the formulae (4-1) and (4-2), ＊ represents a bonding position, and in the formula (4-1), Z represents a bonding bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched 2-valent hydrocarbon group optionally having an oxygen atom at the bonding position, or a 2-valent group having an aromatic ring optionally having an oxygen atom at the bonding position, the hydrogen atom of the aromatic ring in the formulae (4-1) and (4-2) is optionally substituted.

[ solution 5]

In the formulae (5-1) and (5-2), ＊ represents a bonding position, and Y represents a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched 2-valent hydrocarbon group optionally having an oxygen atom at the bonding position, or a 2-valent group having an aromatic ring optionally having an oxygen atom at the bonding position in the formula (5-1) and (5-2), and part or all of hydrogen atoms of the phenylene group in the formulae (5-1) and (5-2) are optionally substituted with a hydroxyl group or a 1-valent hydrocarbon group.

Specific examples of the method for reacting the acid dianhydride represented by the above formula (1) with the diamine represented by the above formula (2) will be shown below.

First, a diamine represented by the above formula (2) is dissolved in advance in a solvent (for example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, or the like) capable of dissolving an amic acid oligomer obtained by the reaction, and an acid dianhydride represented by the above formula (1) is added to the obtained solution to react the solution, thereby obtaining an amic acid oligomer solution. Then, the solvent is removed from the obtained amic acid oligomer solution by heating, reducing the pressure, or the like, or the solution is put into a poor solvent such as water, methanol, hexane, or the like to reprecipitate, thereby recovering the amic acid oligomer, and further, the imidization reaction is carried out by heating at about 200 ℃ or higher for 1 hour or more. By adjusting the molar ratio of the acid dianhydride represented by the formula (1) to the diamine represented by the formula (2) and the imidization conditions, an imide oligomer having a desired number average molecular weight and having an acid anhydride group as a reactive functional group at both ends can be obtained.

Specific examples of the method for reacting the acid dianhydride represented by the above formula (1) with the phenol hydroxyl group-containing monoamine represented by the above formula (3) will be shown below.

First, a phenolic hydroxyl group-containing monoamine represented by formula (3) is dissolved in advance in a solvent (for example, N-methylpyrrolidone or the like) capable of dissolving an amic acid oligomer obtained by the reaction, and an acid dianhydride represented by formula (1) is added to the resulting solution to cause the reaction, thereby obtaining an amic acid oligomer solution. Then, the solvent is removed from the obtained amic acid oligomer solution by heating, reducing the pressure, or the like, or the solution is put into a poor solvent such as water, methanol, hexane, or the like to reprecipitate, thereby recovering the amic acid oligomer, and further, the imidization reaction is carried out by heating at about 200 ℃ or higher for 1 hour or more. By adjusting the molar ratio of the acid dianhydride represented by the formula (1) to the phenolic hydroxyl group-containing monoamine represented by the formula (3) and the imidization conditions, an imide oligomer having a desired number average molecular weight and having phenolic hydroxyl groups as reactive functional groups at both ends can be obtained.

Specific examples of the method of reacting the acid dianhydride represented by the formula (1) with the diamine represented by the formula (2) and then further reacting the phenol hydroxyl group-containing monoamine represented by the formula (3) will be described below.

First, a diamine represented by the above formula (2) is dissolved in advance in a solvent (for example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, or the like) capable of dissolving an amic acid oligomer obtained by the reaction, and an acid dianhydride represented by the above formula (1) is added to the obtained solution to cause the reaction, thereby obtaining a solution of an amic acid oligomer (a) having an acid anhydride group at both terminals. Next, the amic acid oligomer (a) is recovered by removing the solvent from the solution of the amic acid oligomer (a) obtained by heating, reducing the pressure, or the like, or by reprecipitating the solution by pouring the solution into a poor solvent such as water, methanol, hexane, or the like, and further heated at about 200 ℃ or higher for 1 hour or more to effect imidization.

The imide oligomer having an acid anhydride group as a reactive functional group at both ends obtained in this manner is dissolved again in a solvent (for example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, or the like) in which the imide oligomer can be dissolved, and a phenol hydroxyl group-containing monoamine represented by the above formula (3) is added to react the imide oligomer and the solvent to obtain a solution of the amic acid oligomer (B). The amic acid oligomer (B) is recovered by removing the solvent from the solution of the amic acid oligomer (B) obtained by heating, reducing the pressure, or the like, or by reprecipitating the solution by pouring the solution into a poor solvent such as water, methanol, hexane, or the like, and further heated at about 200 ℃ or higher for 1 hour or more to effect the imidization reaction. By adjusting the molar ratio of the acid dianhydride represented by the formula (1) to the diamine represented by the formula (2) to the phenolic hydroxyl group-containing monoamine represented by the formula (3) and the amidation conditions, an imide oligomer having a desired number average molecular weight and having phenolic hydroxyl groups as reactive functional groups at both ends can be obtained.

Examples of the acid dianhydride represented by the above formula (1) include pyromellitic dianhydride, 3, 3 '-oxydiphthalic dianhydride, 3, 4' -oxydiphthalic dianhydride, 4, 4 '- (4, 4' -isopropylidenediphenoxy) diphthalic anhydride, 4, 4 '-bis (3, 4-dicarboxyphenoxy) diphenyl ether, bis (trimellitic anhydride) p-phenyl ester, 2, 3, 3', 4 '-biphenyltetracarboxylic dianhydride, 3, 3', 4, 4 '-biphenyltetracarboxylic dianhydride, and 4, 4' -carbonyldiphthalic dianhydride. Among them, 4 ' - (4, 4 ' -isopropylidenediphenoxy) diphthalic anhydride, 3, 4 ' -oxydiphthalic dianhydride, 4 ' -oxydiphthalic dianhydride, and 4, 4 ' -carbonyldiphthalic dianhydride are preferable from the viewpoint of excellent solubility, heat resistance, and acquisition properties.

Examples of the diamine represented by the formula (2) include 3, 3 '-diaminodiphenylmethane, 3, 4' -diaminodiphenylmethane, 4 '-diaminodiphenylmethane, 3' -diaminodiphenyl ether, 3, 4 '-diaminodiphenyl ether, 4' -diaminodiphenyl ether, 1, 2-phenylenediamine, 1, 3-phenylenediamine, 1, 4-phenylenediamine, 3 '-diaminodiphenyl sulfone, 4' -diaminodiphenyl sulfone, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 1, 3-bis (3-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, and mixtures thereof, 1, 4-bis (4-aminophenoxy) benzene, bis (4- (4-aminophenoxy) phenyl) methane, 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 ' -diamino-4, 4 ' -dihydroxyphenylmethane, 4 ' -diamino-3, 3 ' -dihydroxyphenylmethane, 3 ' -diamino-4, 4 ' -dihydroxyphenyl ether, bisaminophenylfluorene, bistoluenefluorene, 4 ' -bis (4-aminophenoxy) biphenyl, bis (4-aminophenoxy) phenyl, bis (4-aminophenyl) methane, bis (4-aminophenyl) benzene, bis (4-aminophenyl) propane, 1, 4-bis (4-aminophenyl) benzene, 1, 4, 4 '-diamino-3, 3' -dihydroxyphenyl ether, 3 '-diamino-4, 4' -dihydroxybiphenyl, 4 '-diamino-2, 2' -dihydroxybiphenyl, and the like. Among them, from the viewpoint of excellent solubility, heat resistance and acquisition properties, 3, 4 ' -diaminodiphenyl ether, 4 ' -diaminodiphenyl ether, 1, 2-phenylenediamine, 1, 3-phenylenediamine, 1, 4-phenylenediamine, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 1, 3-bis (2- (4-aminophenyl) -2-propyl) benzene, 1, 3-bis (3-aminophenoxy) benzene, 1, 4-bis (2- (4-aminophenyl) -2-propyl) benzene and 3, 3 ' -dihydroxybenzidine are preferable.

Examples of the monoamine having a phenolic hydroxyl group represented by the above formula (3) include 3-aminophenol, 4-aminoo-cresol, 5-aminoo-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, and 4-amino-2, 6-diphenylphenol. Among them, 3-aminophenol, 4-aminoo-cresol, and 5-aminoo-cresol are preferable from the viewpoint of obtaining a cured product having excellent acquisition properties and storage stability and a high glass transition temperature.

The preferable lower limit of the imidization ratio of the imide oligomer is 70%. By setting the imidization ratio to 70% or more, a cured product having more excellent mechanical strength at high temperatures and long-term heat resistance can be obtained. The imidization rate is more preferably 75% or less, and still more preferably 80% or less. The preferable upper limit of the imidization degree of the imide oligomer is not particularly limited, and the substantial upper limit is 98%.

The "imidization ratio" can be obtained by a fourier transform infrared spectroscopy (FT-IR). Specifically, the measurement can be carried out by total reflectance measurement (ATR method) using a Fourier transform infrared spectrophotometer (for example, "UMA 600" manufactured by Agilent Technologies), and 1660cm from carbonyl group derived from amic acid can be obtained by the following formula^-1The area of absorbance of the peak in the vicinity. The "peak absorbance area of the amic acid oligomer" in the following formula means: the absorbance area of the amic acid oligomer obtained by removing the solvent by evaporation without performing the imidization step in the above-described production method.

Imidization ratio (%) < 100 × (1- (peak absorbance area after imidization)/(peak absorbance area of amic acid oligomer))

The imide oligomer may be used alone or in combination of two or more.

The number average molecular weight of the imide oligomer has a preferred lower limit of 400 and a preferred upper limit of 5000. When the number average molecular weight is in this range, the resulting cured product has more excellent long-term heat resistance. The number average molecular weight of the imide oligomer has a more preferable lower limit of 500 and a more preferable upper limit of 4000.

The preferable upper limit of the softening point of the imide oligomer is 250 ℃. By setting the softening point of the imide oligomer to 250 ℃ or lower, the adhesiveness and long-term heat resistance of the resulting cured product become more excellent. A more preferable upper limit of the softening point of the imide oligomer is 200 ℃.

The preferable lower limit of the softening point of the imide oligomer is not particularly limited, and the lower limit is substantially 60 ℃.

The softening point of the imide oligomer can be determined by the ring and ball method in accordance with JIS K2207.

The content of the imide oligomer in 100 parts by weight of the total of the thermosetting resin, the thermoplastic resin, and the imide oligomer preferably has a lower limit of 10 parts by weight and an upper limit of 90 parts by weight. When the content of the imide oligomer is in this range, a cured product of the obtained curable resin composition is more excellent in mechanical strength, adhesiveness, and long-term heat resistance at high temperatures. The content of the imide oligomer is more preferably 20 parts by weight in the lower limit and 80 parts by weight in the upper limit.

The curable resin composition of the present invention 1 may contain other curing agents in addition to the imide oligomer as long as the object of the present invention is not impaired.

Examples of the other curing agent include a phenol curing agent, a thiol curing agent, an amine curing agent, an acid anhydride curing agent, a cyanate curing agent, and an active ester curing agent. Among them, preferred are phenol-based curing agents, acid anhydride-based curing agents, cyanate-based curing agents, and active ester-based curing agents.

When the curable resin composition of the present invention 1 contains the other curing agent, the content of the other curing agent is preferably 70 parts by weight or more, more preferably 50 parts by weight or more, and still more preferably 30 parts by weight or more, based on 100 parts by weight of the total of the imide oligomer and the other curing agent.

The curable resin composition of the present invention 1 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, phosphorus-based curing accelerators, photobase generators, sulfonium salt-based curing accelerators, and the like. Among them, imidazole-based curing accelerators are preferable from the viewpoint of excellent storage stability.

The lower limit of the content of the curing accelerator is preferably 0.01 part by weight, and the upper limit is preferably 10 parts by weight, based on 100 parts by weight of the thermosetting resin. When the content of the curing accelerator is in this range, the effect of shortening the curing time while maintaining excellent adhesiveness and the like becomes more excellent. The lower limit of the content of the curing accelerator is more preferably 0.05 part by weight, and the upper limit is more preferably 5 parts by weight.

The curable resin composition of the present invention 1 may contain an inorganic filler for the purpose of reducing warpage by reducing the linear expansion coefficient after curing, improving adhesion reliability, and the like. In addition, the above inorganic filler may also be suitably used as a flow regulator.

Examples of the inorganic filler include silica such as fumed silica and colloidal silica; alumina, aluminum nitride, boron nitride, silicon nitride, glass powder, glass frit, glass fiber, carbon fiber, inorganic ion exchanger, and the like.

The upper limit of the content of the inorganic filler is preferably 500 parts by weight with respect to 100 parts by weight of the thermosetting resin. By setting the content of the inorganic filler to 500 parts by weight or less, the effects of improving adhesion reliability, adjusting flow, and the like are further enhanced while maintaining excellent workability and the like. A more preferable upper limit of the content of the inorganic filler is 400 parts by weight.

The curable resin composition of the present invention 1 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 preferable.

The upper limit of the content of the organic filler is preferably 500 parts by weight with respect to 100 parts by weight of the thermosetting resin. By setting the content of the organic filler to 500 parts by weight or less, the toughness and the like of the obtained cured product become more excellent while maintaining excellent adhesiveness and the like. The more preferable upper limit of the content of the organic filler is 400 parts by weight.

The curable resin composition of the present invention 1 may contain a reactive diluent within a range not impairing the object of the present invention.

As the reactive diluent, a reactive diluent having 2 or more reactive functional groups in 1 molecule is preferable from the viewpoint of adhesion reliability.

Examples of the reactive functional group of the reactive diluent include the same reactive functional group as that of the polymer compound.

The curable resin composition of the present invention 1 may further contain additives such as a solvent, a coupling agent, a dispersant, a storage stabilizer, a bleeding inhibitor, and a flux.

Examples of the method for producing the curable resin composition of the present invention 1 include a method of mixing a thermosetting resin, a thermoplastic resin, a curing agent, and if necessary, other curing agents, curing accelerators, inorganic fillers (flow control agents), and the like using a mixer such as a homogenizing disperser, a universal mixer, a banbury mixer, or a kneader.

The lower limit of the minimum melt viscosity of the curable resin composition of the present invention 1 is preferably 5kPa · s, and the upper limit is preferably 300kPa · s. When the minimum melt viscosity is within this range, the curable resin composition of the present invention 1 has more excellent flow characteristics. The minimum melt viscosity is preferably 10kPa · s at the lower limit, more preferably 200kPa · s at the upper limit, and still more preferably 150kPa · s at the upper limit.

The minimum melt viscosity can be determined from the lowest complex viscosity in the measurement temperature range of 60 to 300 ℃ under the conditions of a temperature rise rate of 10 ℃/min, a frequency of 1Hz, and a strain of 1% using a rotary rheometer apparatus (for example, "VAR-100" manufactured by REOLOGICA).

The curable resin composition of the present invention 1 can be used in a wide range of applications, and is particularly suitable for electronic material applications requiring high heat resistance. The resin composition can be used for chip mounting agents in applications such as Electric Control Units (ECUs) for aviation and vehicles, and power devices using SiC and GaN. Further, the resin composition can be used for, for example, an adhesive for a power overlay package, an adhesive for a printed wiring board, an adhesive for a coverlay film of a flexible printed wiring board, a copper-clad laminate, an adhesive for bonding a semiconductor, an interlayer insulating film, a prepreg, an encapsulant for an LED, an adhesive for a structural material, and the like. Among them, the adhesive is suitable for use in an adhesive, and particularly suitable for use in an adhesive for a cover lay film of a flexible printed wiring board.

An adhesive comprising the curable resin composition of the present invention 1 (hereinafter also referred to as "the adhesive of the present invention 1") is also one aspect of the present invention. The adhesive of the present invention 1 can be applied to a release film and then dried to form an adhesive film (curable resin composition film), and the adhesive film is cured to obtain a cured product. The cured product of the curable resin composition of the present invention 1 is also one of the present invention.

An adhesive film using the adhesive of the present invention 1 is also one aspect of the present invention.

Further, a cover lay film having an insulating film and an adhesive layer comprising a cured product of the curable resin composition of the present invention 1 (hereinafter also referred to as "the cover lay film of the present invention 1") is also one aspect of the present invention. Further, a flexible printed wiring board having the coverlay film of the present invention 1 is also one aspect of the present invention.

The present invention 2 is a curable resin composition containing a curable resin, an imide oligomer and a curing accelerator, wherein the imide oligomer is represented by the following formula (6).

[ solution 6]

In the formula (6), X is a 4-valent group represented by the following formula (7-1), (7-2) or (7-3), and Y is a 2-valent group represented by the following formula (8-1), (8-2), (8-3) or (8-4).

[ solution 7]

In the formulae (7-1) to (7-3), ＊ represents a bonding position, and the hydrogen atoms of the aromatic rings in the formulae (7-1) to (7-3) are optionally substituted.

[ solution 8]

In the formulae (8-1) and (8-2), Z is a bond, an oxygen atom, a sulfonyl group, a linear or branched 2-valent hydrocarbon group optionally having an oxygen atom at the bonding position, or a 2-valent group having an aromatic ring optionally having an oxygen atom at the bonding position. The hydrogen atoms of the aromatic rings in the formulae (8-1) and (8-2) are optionally substituted. In the formulae (8-3) and (8-4), R⁷～R¹⁴Represents a hydrogen atom or a 1-valent hydrocarbon group, each of which may be the same or different, and ＊ represents a bonding site in the formulae (8-1) to (8-4).

The present invention 2 is described in detail below.

The inventors of the present invention found that: the present inventors have completed the present invention 2 by finding that a curable resin composition containing a curable resin, an imide oligomer, and a curing accelerator can obtain a cured product having excellent storage stability, low linear expansibility, adhesiveness, and long-term heat resistance by using an imide oligomer having a specific structure as the imide oligomer.

The curable resin composition of the present invention 2 contains an imide oligomer.

The imide oligomer is represented by the formula (6). Hereinafter, the imide oligomer represented by the above formula (6) is also referred to as the imide oligomer according to the present invention 2. By containing the imide oligomer of the present invention 2, the curable resin composition of the present invention 2 can provide a cured product having excellent storage stability and excellent low linear expansion properties, adhesiveness, and long-term heat resistance.

The imide oligomer of the present invention 2 has a preferred lower limit of the number average molecular weight of 400 and a preferred upper limit of 5000. When the number average molecular weight is in this range, the resulting cured product has more excellent adhesiveness and long-term heat resistance. The imide oligomer of the present invention 2 has a more preferable lower limit of the number average molecular weight of 500 and a more preferable upper limit of 4000.

The preferable upper limit of the softening point of the imide oligomer of the present invention 2 is 250 ℃. By setting the softening point of the imide oligomer of the present invention 2 to 250 ℃ or lower, the adhesiveness and long-term heat resistance of the resulting cured product become more excellent. A more preferable upper limit of the softening point of the imide oligomer of the present invention 2 is 200 ℃.

The preferable lower limit of the softening point of the imide oligomer of the present invention 2 is not particularly limited, and the substantial lower limit is 60 ℃.

The softening point can be determined by the ring and ball method in accordance with JIS K2207.

Examples of the method for producing the imide oligomer of the present invention 2 include a method in which an acid dianhydride represented by the following formula (9) is reacted with a diamine represented by the following formula (10).

[ solution 9]

In the formula (9), X is the same group having a valence of 4 as X in the formula (6).

[ solution 10]

In the formula (10), Y is the same 2-valent group as Y in the formula (6), R¹⁵～R¹⁸Each independently a hydrogen atom or a 1-valent hydrocarbon group.

Specific examples of the method for reacting the acid dianhydride represented by the above formula (9) with the diamine represented by the above formula (10) will be shown below.

First, a diamine represented by the above formula (10) is dissolved in advance in a solvent (for example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, or the like) capable of dissolving an amic acid oligomer obtained by the reaction, and an acid dianhydride represented by the above formula (9) is added to the resulting solution and reacted to obtain an amic acid oligomer solution. Then, the solvent is removed from the obtained amic acid oligomer solution by heating, reducing the pressure, or the like, or the solution is put into a poor solvent such as water, methanol, hexane, or the like to reprecipitate, thereby recovering the amic acid oligomer, and further, the imidization reaction is carried out by heating at about 200 ℃ or higher for 1 hour or more. By adjusting the molar ratio of the acid dianhydride represented by the formula (9) to the diamine represented by the formula (10) and the imidization conditions, an imide oligomer represented by the formula (6) and having a desired number average molecular weight can be obtained.

Specific examples of the acid dianhydride represented by the above formula (9) include 3, 4 '-oxydiphthalic dianhydride, 4' -oxydiphthalic dianhydride, and 4, 4 '- (4, 4' -isopropylidenediphenoxy) diphthalic anhydride.

Examples of the diamine represented by the above formula (10) include 3, 3 '-diaminodiphenylmethane, 4' -diaminodiphenylmethane, 3 '-diaminodiphenyl ether, 4' -diaminodiphenyl ether, 1, 3-phenylenediamine, 1, 4-phenylenediamine, 3 '-diaminodiphenyl sulfone, 4' -diaminodiphenyl sulfone, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 1, 3-bis (3-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, bis (4- (4-aminophenoxy) phenyl) methane, bis (4-aminophenoxy) phenyl) methane, and mixtures thereof, 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, bisaminophenylfluorene, 4' -bis (4-aminophenoxy) biphenyl, diethyltoluenediamine, and the like. Among them, from the viewpoint of excellent solubility, heat resistance and acquisition properties, 1, 3-bis (3-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, 1, 4-bis (4-aminophenoxy) benzene, 1, 3-phenylenediamine, 1, 4-phenylenediamine, 3 '-diaminodiphenyl sulfone, 4' -diaminodiphenyl sulfone, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, diethyltoluenediamine, 3 '-diaminodiphenylmethane and 4, 4' -diaminodiphenylmethane are preferable. In addition, 1, 3-bis (4-aminophenoxy) benzene is particularly preferable from the viewpoint of excellent low linear expansibility.

The preferable lower limit of the imidization ratio of the imide oligomer of the present invention 2 is 70%. By setting the imidization ratio to 70% or more, a cured product having more excellent mechanical strength at high temperatures and long-term heat resistance can be obtained. The imidization rate is more preferably 75% or less, and still more preferably 80% or less. The upper limit of the imidization degree of the imide oligomer according to the present invention 2 is not particularly limited, and the substantial upper limit is 98%.

The "imidization ratio" can be obtained by a fourier transform infrared spectroscopy (FT-IR). Specifically, the measurement can be carried out by total reflectance measurement (ATR method) using a Fourier transform infrared spectrophotometer (e.g., Agilent Technologies, "UMA 600", etc.), and the carbonyl group derived from amic acid can be derived from the following formula1660cm^-1The area of absorbance of the peak in the vicinity. The "peak absorbance area of the amic acid oligomer" in the following formula means: the absorbance area of the amic acid oligomer obtained by reacting the acid dianhydride represented by formula (9) with the diamine represented by formula (10) and then removing the solvent by evaporation without performing the imidization step.

The content of the imide oligomer of the present invention 2 in 100 parts by weight of the total of the curable resin, the imide oligomer and the curing accelerator preferably has a lower limit of 20 parts by weight and an upper limit of 90 parts by weight. When the content of the imide oligomer of the present invention 2 is in this range, the cured product of the curable resin composition obtained is more excellent in mechanical strength, adhesiveness and long-term heat resistance at high temperatures. The content of the imide oligomer according to the present invention 2 is more preferably 30 parts by weight in the lower limit and 80 parts by weight in the upper limit.

The curable resin composition of the present invention 2 may contain another imide oligomer and another curing agent in addition to the imide oligomer described in the present invention 2, within a range not impairing the object of the present invention.

Examples of the other imide oligomer include, for example, an imide oligomer having an imide group and a reactive functional group in the molecule, other than the imide oligomer described in the present invention 2.

When the curable resin composition of the present invention 2 contains the other imide oligomer or the other curing agent, the content of the other imide oligomer or the other curing agent in the entire curing agent is preferably 70% by weight, more preferably 50% by weight, and still more preferably 30% by weight.

The curable resin composition of the present invention 2 contains a curable resin.

As the curable resin, an epoxy resin is suitably used.

The curable resin composition of the present invention 2 contains a curing accelerator. By containing the curing accelerator, not only the curing time can be shortened to improve the productivity, but also the long-term heat resistance of the cured product can be improved.

The curing accelerator is preferably a basic catalyst, and examples thereof include curing accelerators having an imidazole skeleton (imidazole curing accelerators), tertiary amine curing accelerators, phosphorus curing accelerators, and photobase generators. Among them, a curing accelerator having an imidazole skeleton is more preferable from the viewpoint of excellent storage stability.

Examples of the curing accelerator having an imidazole skeleton include 2-methylimidazole, 2-undecylimidazole, 2-heptadecylimidazole, 2-ethyl-4-methylimidazole, 2-phenylimidazole, 2-phenyl-4-methylimidazole, 1-benzyl-2-phenylimidazole, 1, 2-dimethylimidazole, 1-cyanoethyl-2-methylimidazole, 1-cyanoethyl-2-ethyl-4-methylimidazole, 1-cyanoethyl-2-undecylimidazole, 1-cyanoethyl-2-phenylimidazole, 2, 4-diamino-6- (2 '-methylimidazolyl- (1')) -ethyl-s-triazine, and mixtures thereof, 2, 4-diamino-6- (2 ' -undecylimidazolyl- (1 ')) -ethyl-s-triazine, 2, 4-diamino-6- (2 ' -ethyl-4 ' -methylimidazolyl- (1 ')) -ethyl-s-triazine, 2, 4-diamino-6- (2 ' -methylimidazolyl- (1 '))) -ethyl-s-triazine isocyanuric acid adduct, 2-phenylimidazole isocyanuric acid adduct, 2-methylimidazole isocyanuric acid adduct, 2-phenyl-4, 5-dihydroxymethylimidazole, 2-phenyl-4-methyl-5-hydroxymethylimidazole and the like.

Examples of the other curing accelerators than the curing accelerator having an imidazole skeleton include tertiary amine-based curing accelerators, phosphine-based curing accelerators, photobase generators, sulfonium salt-based curing accelerators, and the like.

The content of the curing accelerator in 100 parts by weight of the total of the curable resin, the imide oligomer and the curing accelerator preferably has a lower limit of 0.8 part by weight and an upper limit of 10 parts by weight. When the content of the curing accelerator is 0.8 parts by weight or more, the cured product of the obtained curable resin composition has more excellent adhesiveness and long-term heat resistance. By setting the content of the curing accelerator to 10 parts by weight or less, the storage stability of the obtained curable resin composition becomes more excellent. The lower limit of the content of the curing accelerator is more preferably 1 part by weight, and the upper limit is more preferably 9 parts by weight.

The curable resin composition of the present invention 2 may contain an inorganic filler for the purpose of reducing warpage by reducing the linear expansion coefficient after curing, improving adhesion reliability, or the like. In addition, the inorganic filler can also be suitably used as a flow regulator.

Examples of the inorganic filler include silica such as fumed silica and colloidal silica, alumina, aluminum nitride, boron nitride, silicon nitride, glass powder, glass frit, glass fiber, carbon fiber, and inorganic ion exchanger.

The upper limit of the content of the inorganic filler is preferably 300 parts by weight based on 100 parts by weight of the curable resin. By setting the content of the inorganic filler to 300 parts by weight or less, the effects of improving adhesion reliability, adjusting flow, and the like are further enhanced while maintaining excellent workability and the like. The content of the inorganic filler is more preferably 200 parts by weight.

The curable resin composition of the present invention 2 may contain an organic filler for the purpose of relaxing stress, imparting toughness, and the like.

The upper limit of the content of the organic filler is preferably 300 parts by weight based on 100 parts by weight of the curable resin. By setting the content of the organic filler to 300 parts by weight or less, the toughness and the like of the obtained cured product become more excellent while maintaining excellent adhesiveness and the like. The content of the organic filler is more preferably 200 parts by weight.

The curable resin composition of the present invention 2 may contain a polymer compound in a range not to impair the object of the present invention. The polymer compound exerts an effect as a film-forming component.

The polymer compound may have a reactive functional group.

Examples of the reactive functional group include an amino group, a urethane group, an imide group, a hydroxyl group, a carboxyl group, and an epoxy group.

The curable resin composition of the present invention 2 may contain a reactive diluent within a range not impairing the object of the present invention.

The reactive diluent is preferably a reactive diluent having 2 or more reactive functional groups in 1 molecule from the viewpoint of adhesion reliability.

The curable resin composition of the present invention 2 may further contain additives such as a solvent, a coupling agent, a dispersant, a storage stabilizer, a bleeding inhibitor, a flux, a leveling agent, and a flame retardant.

Examples of the method for producing the curable resin composition of the present invention 2 include a method of mixing a curable resin, the imide oligomer of the present invention 2, a curing accelerator, and, if necessary, other curing agents, inorganic fillers (flow control agents), and the like, using a mixer such as a homogenizing disperser, a universal mixer, a banbury mixer, or a kneader.

Further, a film containing the curable resin composition of the present invention 2 can be obtained by applying the curable resin composition of the present invention 2 on a film and drying the film, and a cured product can be obtained by curing the curable resin composition film. A cured product of the curable resin composition of the present invention 2 (hereinafter also referred to as "cured product of the present invention 2") is also one aspect of the present invention.

From the viewpoint of reducing warpage and improving adhesion reliability, the cured product of the present invention 2 preferably has an average linear expansion coefficient of 60ppm or less, more preferably 55ppm or less, at a temperature of 40 to 80 ℃. The smaller the average linear expansion coefficient is, the more preferable the smaller the average linear expansion coefficient is.

The average linear expansion coefficient can be measured with a thermomechanical analyzer for a cured product having a thickness of about 400 μm. Specifically, a cured product having a sample length of 1cm was heated from 0 ℃ to 300 ℃ under the conditions of a load of 5g and a heating rate of 10 ℃/min, then cooled once and again heated from 0 ℃ to 300 ℃ under the same conditions, and the average linear expansion coefficient in the temperature range of 40 ℃ to 80 ℃ was determined based on the data of the temperature and dimensional change obtained in the 2 nd measurement.

The cured product for measuring the average linear expansion coefficient can be obtained by heating the curable resin composition film at 190 ℃ for 30 minutes or more.

Examples of the thermomechanical analyzer include TMA/SS-6000 (manufactured by Hitachi high-tech Co., Ltd.).

The curable resin composition of the present invention 2 can be used in a wide range of applications, and is particularly suitable for electronic material applications requiring high heat resistance. The resin composition can be used for chip mounting agents in applications such as Electric Control Units (ECUs) for aviation and vehicles, and power devices using SiC and GaN. Further, the resin composition can be used for, for example, an adhesive for a power overlay package, an adhesive for a printed circuit board, an adhesive for an overlay of a flexible printed circuit board, a copper-clad laminate, an adhesive for bonding a semiconductor, an interlayer insulating film, a prepreg, an encapsulant for an LED, an adhesive for a structural material, and the like. Among them, the resin composition is suitable for adhesive applications.

An adhesive comprising the curable resin composition of the present invention 2 is also one of the present invention. An adhesive film formed using the curable resin composition of the present invention 2 is also one aspect of the present invention.

The present invention 3 is a curable resin composition comprising a curable resin and an imide oligomer, wherein the curable resin is in a liquid state at 25 ℃ and the imide oligomer is dispersed in a solid particle state at 25 ℃.

The present invention 3 is described in detail below.

The present inventors studied: in a curable resin composition containing a curable resin and an imide oligomer, a curable resin which is in a liquid state at 25 ℃ is used as the curable resin, and the imide oligomer is dispersed in a solid particle state at 25 ℃. As a result, they found that: a curable resin composition excellent in flexibility and processability before curing and excellent in adhesiveness and heat resistance after curing can be obtained, and the present invention 3 has been completed.

The curable resin composition of the present invention 3 contains a curable resin.

The curable resin is in a liquid state at 25 ℃. The curable resin composition of the present invention 3 has excellent flowability and processability by making the curable resin liquid at 25 ℃. In order to disperse the imide oligomer described later in the form of solid particles, a curable resin in which the imide oligomer is insoluble at 25 ℃ is used as the curable resin.

As the curable resin, an epoxy resin is suitably used.

The curable resin composition of the present invention 3 contains an imide oligomer. In the curable resin composition of the present invention 3, the imide oligomer is dispersed in the form of solid particles at 25 ℃. By dispersing the imide oligomer in the form of solid particles, the curable resin composition of the present invention 3 can provide a cured product having excellent flexibility, adhesiveness, and heat resistance while maintaining excellent flowability and processability.

The above "dispersed in solid particles" means: the particles were present in a particulate form without dissolving, and most of the particles were dispersed, rather than agglomerated, and were present in a heavy state, and were confirmed by direct observation using an optical microscope or an electron microscope.

The imide oligomer preferably has a reactive functional group capable of reacting with the curable resin.

The reactive functional group varies depending on the type of the curable resin used, but when an epoxy resin is used as the curable resin, an acid anhydride group and/or a phenolic hydroxyl group is preferable.

Examples of the method for producing the imide oligomer having an acid anhydride group as the reactive functional group include a method in which an acid dianhydride represented by the following formula (11) is reacted with a diamine represented by the following formula (12).

Examples of the method for producing an imide oligomer having a phenolic hydroxyl group as the reactive functional group include the following methods.

Examples thereof include: a method in which an acid dianhydride represented by the following formula (11) is reacted with a phenol hydroxyl group-containing monoamine represented by the following formula (13); a method comprising reacting an acid dianhydride represented by the following formula (11) with a diamine represented by the following formula (12), and then further reacting a phenol hydroxyl group-containing monoamine represented by the following formula (13).

[ solution 11]

In the formula (11), A is a 4-valent group represented by the following formula (14-1) or the following formula (14-2).

[ solution 12]

In the formula (12), B is a 2-valent group represented by the following formula (15-1) or the following formula (15-2), R¹⁹～R2²Each independently a hydrogen atom or a 1-valent hydrocarbon group.

[ solution 13]

In the formula (13), Ar is an optionally substituted 2-valent aromatic group, R²³And R²⁴Each independently a hydrogen atom or a 1-valent hydrocarbon group.

[ solution 14]

In the formulae (14-1) and (14-2), ＊ represents a bonding position, and in the formula (14-1), Z represents a bonding bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched 2-valent hydrocarbon group optionally having an oxygen atom at the bonding position, or a 2-valent group having an aromatic ring optionally having an oxygen atom at the bonding position, the hydrogen atom of the aromatic ring in the formulae (14-1) and (14-2) is optionally substituted.

[ solution 15]

In the formulae (15-1) and (15-2), ＊ represents a bonding position, and Y represents a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched 2-valent hydrocarbon group optionally having an oxygen atom at the bonding position, or a 2-valent group having an aromatic ring optionally having an oxygen atom at the bonding position in the formula (15-1) and (15-2), and part or all of hydrogen atoms of the phenylene group in the formulae (15-1) and (15-2) are optionally substituted with a hydroxyl group or a 1-valent hydrocarbon group.

Specific examples of the method for reacting the acid dianhydride represented by the above formula (11) with the diamine represented by the above formula (12) will be shown below.

First, a diamine represented by the above formula (12) is dissolved in advance in a solvent (for example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, or the like) capable of dissolving an amic acid oligomer obtained by the reaction, and an acid dianhydride represented by the above formula (11) is added to the resulting solution to react the solution, thereby obtaining an amic acid oligomer solution. Then, the solvent is removed from the obtained amic acid oligomer solution by heating, reducing the pressure, or the like, or the solution is put into a poor solvent such as water, methanol, hexane, or the like to reprecipitate, thereby recovering the amic acid oligomer, and further, the imidization reaction is carried out by heating at about 200 ℃ or higher for 1 hour or more. By adjusting the molar ratio of the acid dianhydride represented by the formula (11) to the diamine represented by the formula (12) and the imidization conditions, an imide oligomer having a desired number average molecular weight and having an acid anhydride group as a reactive functional group at both ends can be obtained.

Specific examples of the method for reacting the acid dianhydride represented by the above formula (11) with the phenol hydroxyl group-containing monoamine represented by the above formula (13) will be shown below.

First, a phenolic hydroxyl group-containing monoamine represented by formula (13) is dissolved in advance in a solvent (for example, N-methylpyrrolidone or the like) capable of dissolving an amic acid oligomer obtained by the reaction, and an acid dianhydride represented by formula (11) is added to the resulting solution to cause the reaction, thereby obtaining an amic acid oligomer solution. Then, the solvent is removed from the obtained amic acid oligomer solution by heating, reducing the pressure, or the like, or the solution is put into a poor solvent such as water, methanol, hexane, or the like to reprecipitate, thereby recovering the amic acid oligomer, and further, the imidization reaction is carried out by heating at about 200 ℃ or higher for 1 hour or more. By adjusting the molar ratio of the acid dianhydride represented by the above formula (11) to the phenolic hydroxyl group-containing monoamine represented by the above formula (13) and the imidization conditions, an imide oligomer having a desired number average molecular weight and having phenolic hydroxyl groups as reactive functional groups at both ends can be obtained.

Specific examples of the method of reacting the acid dianhydride represented by the formula (11) with the diamine represented by the formula (12) and then further reacting the phenol hydroxyl group-containing monoamine represented by the formula (13) will be described below.

First, a diamine represented by the above formula (12) is dissolved in advance in a solvent (for example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, or the like) capable of dissolving an amic acid oligomer obtained by the reaction, and an acid dianhydride represented by the above formula (11) is added to the obtained solution to cause the reaction, thereby obtaining a solution of an amic acid oligomer (a) having an acid anhydride group at both terminals. Next, the amic acid oligomer (a) is recovered by removing the solvent from the solution of the amic acid oligomer (a) obtained by heating, reducing the pressure, or the like, or by reprecipitating the solution by pouring the solution into a poor solvent such as water, methanol, hexane, or the like, and further heated at about 200 ℃ or higher for 1 hour or more to effect imidization.

The imide oligomer having an acid anhydride group as a reactive functional group at both ends obtained in this manner is dissolved again in a solvent (for example, N-methylpyrrolidone, dimethylformamide, dimethylacetamide, or the like) in which the imide oligomer can be dissolved, and a phenol hydroxyl group-containing monoamine represented by the above formula (13) is added to react the imide oligomer and the solvent to obtain a solution of the amic acid oligomer (B). The amic acid oligomer (B) is recovered by removing the solvent from the solution of the amic acid oligomer (B) obtained by heating, reducing the pressure, or the like, or by reprecipitating the solution by pouring the solution into a poor solvent such as water, methanol, hexane, or the like, and further heated at about 200 ℃ or higher for 1 hour or more to effect the imidization reaction. By adjusting the molar ratio of the acid dianhydride represented by the formula (11) to the diamine represented by the formula (12) to the phenolic hydroxyl group-containing monoamine represented by the formula (13) and the imidization conditions, an imide oligomer having a desired number average molecular weight and having phenolic hydroxyl groups as reactive functional groups at both ends can be obtained.

Examples of the acid dianhydride represented by the above formula (11) include pyromellitic dianhydride, 3, 3 '-oxydiphthalic dianhydride, 3, 4' -oxydiphthalic dianhydride, 4, 4 '- (4, 4' -isopropylidenediphenoxy) diphthalic anhydride, 4, 4 '-bis (3, 4-dicarboxyphenoxy) diphenyl ether, bis (trimellitic anhydride) p-phenyl ester, 2, 3, 3', 4 '-biphenyltetracarboxylic dianhydride, 3, 3', 4, 4 '-biphenyltetracarboxylic dianhydride, and 4, 4' -carbonyldiphthalic dianhydride. Among them, from the viewpoint of excellent softening point, solubility control, heat resistance and acquisition properties of the imide oligomer, 4 ' - (4, 4 ' -isopropylidenediphenoxy) diphthalic anhydride, 3, 4 ' -oxydiphthalic dianhydride, 4 ' -oxydiphthalic dianhydride and 4, 4 ' -carbonyldiphthalic dianhydride are preferable.

Examples of the diamine represented by the above formula (12) include 3, 3 '-diaminodiphenylmethane, 3, 4' -diaminodiphenylmethane, 4 '-diaminodiphenylmethane, 3' -diaminodiphenyl ether, 3, 4 '-diaminodiphenyl ether, 4' -diaminodiphenyl ether, 1, 2-phenylenediamine, 1, 3-phenylenediamine, 1, 4-phenylenediamine, 3 '-diaminodiphenyl sulfone, 4' -diaminodiphenyl sulfone, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 1, 3-bis (3-aminophenoxy) benzene, 1, 3-bis (4-aminophenoxy) benzene, and mixtures thereof, 1, 4-bis (4-aminophenoxy) benzene, bis (4- (4-aminophenoxy) phenyl) methane, 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 ' -diamino-4, 4 ' -dihydroxyphenylmethane, 4 ' -diamino-3, 3 ' -dihydroxyphenylmethane, 3 ' -diamino-4, 4 ' -dihydroxyphenyl ether, bisaminophenylfluorene, bistoluenefluorene, 4 ' -bis (4-aminophenoxy) biphenyl, bis (4-aminophenoxy) phenyl, bis (4-aminophenyl) methane, bis (4-aminophenyl) benzene, bis (4-aminophenyl) propane, 1, 4-bis (4-aminophenyl) benzene, 1, 4, 4 '-diamino-3, 3' -dihydroxyphenyl ether, 3 '-diamino-4, 4' -dihydroxybiphenyl, 4 '-diamino-2, 2' -dihydroxybiphenyl, and the like. Among them, from the viewpoint of excellent softening point, control of solubility, heat resistance and acquisition property of the imide oligomer, 3, 4 ' -diaminodiphenyl ether, 4 ' -diaminodiphenyl ether, 1, 2-phenylenediamine, 1, 3-phenylenediamine, 1, 4-phenylenediamine, bis (4- (3-aminophenoxy) phenyl) sulfone, bis (4- (4-aminophenoxy) phenyl) sulfone, 1, 3-bis (2- (4-aminophenyl) -2-propyl) benzene, 1, 3-bis (3-aminophenoxy) benzene, 1, 4-bis (2- (4-aminophenyl) -2-propyl) benzene and 3, 3 ' -dihydroxybenzidine are preferable.

Examples of the monoamine having a phenolic hydroxyl group represented by the above formula (13) include 3-aminophenol, 4-aminoo-cresol, 5-aminoo-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, and 4-amino-2, 6-diphenylphenol. Among them, 3-aminophenol, 4-aminoo-cresol, and 5-aminoo-cresol are preferable from the viewpoint of obtaining a cured product having excellent acquisition properties and storage stability and a high glass transition temperature.

The "imidization ratio" can be obtained by a fourier transform infrared spectroscopy (FT-IR). Specifically, the measurement can be carried out by total reflectance measurement (ATR method) using a Fourier transform infrared spectrophotometer (for example, "UMA 600" manufactured by Agilent Technologies), and 1660cm from carbonyl group derived from amic acid can be obtained by the following formula^-1The area of absorbance of the peak in the vicinity. The "peak absorbance area of the amic acid oligomer" in the following formula means: the absorbance area of the amic acid oligomer obtained by removing the solvent after reacting the acid dianhydride represented by formula (11) with each amine compound is not subjected to the imidization step. The solvent may be removed by evaporation.

The imide oligomer may be used alone or in combination of two or more.

The average particle diameter of the imide oligomer in the curable resin composition of the present invention 3 has a preferred lower limit of 0.5 μm and a preferred upper limit of 20 μm. By setting the average particle diameter of the imide oligomer to 0.5 μm or more, the obtained curable resin composition is excellent in flexibility and processability in a state before curing. By setting the average particle size of the imide oligomer to 20 μm or less, the obtained curable resin composition can provide a cured product having excellent uniformity and excellent adhesiveness and heat resistance. The average particle size of the imide oligomer has a more preferable lower limit of 1 μm and a more preferable upper limit of 10 μm.

The preferable upper limit of the softening point of the imide oligomer is 250 ℃. When the softening point of the imide oligomer is 250 ℃ or lower, the adhesiveness and long-term heat resistance of the resulting cured product become more excellent. A more preferable upper limit of the softening point of the imide oligomer is 200 ℃.

The preferable upper limit of the melting point of the imide oligomer is 300 ℃. When the melting point of the imide oligomer is 300 ℃ or lower, the adhesiveness and long-term heat resistance of the obtained curable resin composition become more excellent. A more preferable upper limit of the melting point of the imide oligomer is 250 ℃.

The melting point of the imide oligomer can be determined by differential scanning calorimetry or a commercially available melting point measuring instrument.

The content of the imide oligomer is preferably 30 parts by weight in the lower limit and 500 parts by weight in the upper limit with respect to 100 parts by weight of the curable resin. When the content of the imide oligomer is in this range, a cured product of the obtained curable resin composition is more excellent in mechanical strength, adhesiveness, and long-term heat resistance at high temperatures. The content of the imide oligomer is more preferably 50 parts by weight in the lower limit and 400 parts by weight in the upper limit.

The curable resin composition of the present invention 3 may contain, as the imide oligomer, only an imide oligomer that is insoluble in the curable resin composition at 25 ℃, or an imide oligomer that is insoluble in the curable resin composition at 25 ℃ and an imide oligomer that is soluble in the curable resin composition at 25 ℃. Hereinafter, an imide oligomer that is insoluble in the curable resin composition at 25 ℃ is also referred to as an "insoluble imide oligomer", and an imide oligomer that is soluble in the curable resin composition at 25 ℃ is also referred to as a "soluble imide oligomer". That is, in the curable resin composition of the present invention 3, a part of the imide oligomer (soluble imide oligomer) may be dissolved and a part (insoluble imide oligomer) may be dispersed in a solid particle form. In this case, strong adhesive force can be exhibited by the wettability based on the soluble imide oligomer, and fluidity, processability, and flexibility can be imparted by the insoluble imide oligomer.

The term "insoluble in the curable resin composition" means: the solvent is insoluble in the curable resin when the solvent is not used, and insoluble in the solvent and the curable resin when the solvent is used. The term "soluble in the curable resin composition" means: the solvent is soluble in the curable resin without using a solvent described later, and is soluble in the solvent and the curable resin when using a solvent described later.

In the case of using the soluble imide oligomer, the content of the soluble imide oligomer is preferably 80 parts by weight or less based on 100 parts by weight of the entire imide oligomer. When the content of the soluble imide oligomer is 80 parts by weight or less, the obtained curable resin composition has excellent adhesiveness while maintaining excellent flexibility.

In the case of using the soluble imide oligomer, the content ratio of the soluble imide oligomer is preferably 20 parts by weight or more.

The curable resin composition of the present invention 3 may contain other curing agents in addition to the imide oligomer as long as the object of the present invention is not impaired.

When the curable resin composition of the present invention 3 contains the other curing agent, the content of the other curing agent is preferably 70 parts by weight or more, more preferably 50 parts by weight or more, and still more preferably 30 parts by weight or more, based on 100 parts by weight of the total of the imide oligomer and the other curing agent.

The curable resin composition of the present invention 3 preferably contains a curing accelerator. By containing the curing accelerator, the curing time can be shortened and the productivity can be improved.

The content of the curing accelerator is preferably 0.01 part by weight in the lower limit and 10 parts by weight in the upper limit, based on 100 parts by weight of the curable resin. When the content of the curing accelerator is in this range, the effect of shortening the curing time while maintaining excellent adhesiveness and the like becomes more excellent. The lower limit of the content of the curing accelerator is more preferably 0.05 part by weight, and the upper limit is more preferably 5 parts by weight.

The curable resin composition of the present invention 3 may contain an inorganic filler for the purpose of reducing warpage by reducing the linear expansion coefficient after curing, improving adhesion reliability, or the like. In addition, the inorganic filler can also be suitably used as a flow regulator.

The content of the inorganic filler is preferably up to 500 parts by weight based on 100 parts by weight of the curable resin. By setting the content of the inorganic filler to 500 parts by weight or less, the effects of improving adhesion reliability, adjusting flow, and the like are further enhanced while maintaining excellent workability and the like. A more preferable upper limit of the content of the inorganic filler is 400 parts by weight.

The curable resin composition of the present invention 3 may contain an organic filler for the purpose of relaxing stress, imparting toughness, and the like.

The upper limit of the content of the organic filler is preferably 500 parts by weight based on 100 parts by weight of the curable resin. By setting the content of the organic filler to 500 parts by weight or less, the toughness and the like of the obtained cured product become more excellent while maintaining excellent adhesiveness and the like. The more preferable upper limit of the content of the organic filler is 400 parts by weight.

The curable resin composition of the present invention 3 may contain a polymer compound in a range not to impair the object of the present invention. The polymer compound functions as a film-forming component.

The polymer compound may have a reactive functional group.

When the polymer compound has a reactive functional group, examples of the reactive functional group of the polymer compound include an amino group, a urethane group, an imide group, a hydroxyl group, a carboxyl group, and an epoxy group.

The curable resin composition of the present invention 3 may contain a reactive diluent within a range not impairing the object of the present invention.

The curable resin composition of the present invention 3 may further contain additives such as a solvent, a coupling agent, a dispersant, a storage stabilizer, a bleeding inhibitor, a flux, a leveling agent, and a flame retardant.

Examples of the method for producing the curable resin composition of the present invention 3 include the following methods.

The imide oligomer dispersion is obtained by pulverizing a solid block of the imide oligomer in advance using a pulverizer such as a jet mill, a ball mill, or a bead mill, and dispersing the resultant into a dispersion medium in which the imide oligomer is insoluble. Next, a method of mixing the curable resin, the imide oligomer dispersion, and if necessary, other curing agents, curing accelerators, inorganic fillers (flow control agents), and the like using a mixer such as a homogenizing disperser, a universal mixer, a banbury mixer, or a kneader, and the like.

The curable resin composition of the present invention 3 can be used in a wide range of applications, and is particularly suitable for electronic material applications requiring high heat resistance. The resin composition can be used for chip mounting agents in applications such as Electric Control Units (ECUs) for aviation and vehicles, and power devices using SiC and GaN. Further, the resin composition can be used for, for example, an adhesive for a power overlay package, an adhesive for a printed circuit board, an adhesive for a cover layer of a flexible printed circuit board, a copper-clad laminate, an adhesive for bonding a semiconductor, an interlayer insulating film, a prepreg, an encapsulant for an LED, an adhesive for a structural material, and the like. Among them, the resin composition is suitable for adhesive applications.

An adhesive comprising the curable resin composition of the present invention 3 (hereinafter also referred to as "the adhesive of the present invention 3") is also one aspect of the present invention. An adhesive film (curable resin composition film) can be obtained by a method of applying the adhesive of the present invention 3 to a film and then drying the film, and a cured product can be obtained by curing the adhesive film. A cured product of the curable resin composition of the present invention 3 is also one of the present invention. An adhesive film using the adhesive of the present invention 3 is also one aspect of the present invention.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a curable resin composition having excellent flow characteristics before curing and excellent adhesiveness, heat resistance and bending resistance after curing can be provided. The present invention also provides a cured product of the curable resin composition, and an adhesive, an adhesive film, a coverlay film, and a printed wiring board each using the curable resin composition.

Further, the present invention can provide a curable resin composition which can give a cured product having excellent storage stability and excellent low linear expansibility, adhesiveness, and long-term heat resistance. The present invention also provides a cured product of the curable resin composition, and an adhesive film each using the curable resin composition.

Further, the present invention can provide a curable resin composition which is excellent in flexibility and processability before curing and excellent in adhesiveness and heat resistance after curing. The present invention also provides a cured product of the curable resin composition, and an adhesive film each using the curable resin composition.

Detailed Description

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

Synthesis example 1-1 (preparation of imide oligomer 1-A)

17.2 parts by weight of 1, 4-bis (2- (4-aminophenyl) -2-propyl) benzene (manufactured by Mitsui chemical industries, Ltd., "BISANILINE P") was dissolved in 200 parts by weight of N-methylpyrrolidone (manufactured by Fuji film and Wako pure chemical industries, Ltd.). To the obtained solution, 52.0 parts by weight of 4, 4 '- (4, 4' -isopropylidenediphenoxy) diphthalic anhydride (manufactured by Tokyo chemical Co., Ltd.) was added, and the mixture was stirred at 25 ℃ for 2 hours to cause a reaction, thereby obtaining an amic acid oligomer solution. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, imide oligomer 1-A (imidization rate 97%) was obtained by heating at 300 ℃ for 2 hours.

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 1-A contains an imide oligomer represented by the following formula (16) as a main component. Further, the softening point of the imide oligomer 1-A was 155 ℃.

[ solution 16]

Synthesis example 1-2 (preparation of imide oligomer 1-B)

Imide oligomer 1-B (imidization rate 96%) was obtained in the same manner as in Synthesis example 1-1, except that 17.2 parts by weight of 1, 4-bis (2- (4-aminophenyl) -2-propyl) benzene was changed to 21.8 parts by weight of 3-aminophenol (manufactured by Tokyo chemical industries, Ltd.).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 1-B contains an imide oligomer represented by the following formula (17) as a main component. Further, the softening point of the imide oligomer 1-B was 134 ℃.

[ solution 17]

(examples 1 to 9, comparative examples 1 and 2)

The curable resin compositions of examples 1 to 9 and comparative examples 1 and 2 were prepared by stirring and mixing the respective materials so as to have the mixing ratios shown in tables 1 and 2.

Each of the obtained curable resin compositions was coated on a release PET film to a thickness of 20 μm, and dried to obtain an adhesive film.

The obtained curable resin compositions were applied to a polyimide film (KAPTON 100H, manufactured by Toledo DuPont) having a thickness of 25 μm so as to have a thickness of 20 μm, to prepare a polyimide film (cover film) having an adhesive layer. The release PET film was peeled from the obtained adhesive film, laminated by a laminator so as to have a thickness of 500 μm, measured by a rotary rheometer apparatus (VAR-100, manufactured by REOLOGICA) under conditions of a temperature rise rate of 10 ℃/min, a frequency of 1Hz, a strain of 1% and a measurement temperature range of 60 to 300 ℃, and the measured minimum melt viscosities were shown in tables 1 and 2.

< evaluation >

The following evaluations were made for each of the curable resin compositions, adhesive films, and cover lay films obtained in examples 1 to 9 and comparative examples 1 and 2. The results are shown in tables 1 and 2.

(resistance to leaching)

The coverlay films obtained in examples 1 to 9 and comparative examples 1 and 2 were subjected to punching with a hole of 5mm phi, and then heat-pressure bonded to a flexible copper-clad laminate having a copper wiring pattern with an L/S of 100 μm/100 μm at 190 ℃ under 3MPa for 1 hour, and the length of resin oozing out of the inside of the hole was measured as an amount of leaching, "○" when the resin was not leached (the amount of leaching was less than 0.2mm), "△" when the amount of leaching was 0.2mm or more and 0.5mm or less, and "x" when the amount of leaching exceeded 0.5mm, to evaluate the leaching resistance.

(filling property)

The coverlay films obtained in examples 1 to 9 and comparative examples 1 and 2 were heat-pressed to a flexible copper-clad laminate having a copper wiring pattern with an L/S of 100 μm/100 μm at 190 ℃ for 1 hour under 3MPa, and the presence or absence of voids between the copper wiring patterns was observed with an optical microscope.

The filling property was evaluated by designating "○" when no voids were present between the wirings and the filling property was good, designating "△" when voids were slightly observed between the wirings and the filling property was substantially good, and designating "x" when a large number of voids were observed between the wirings and the filling property was insufficient.

(adhesiveness)

The PET film was peeled from the adhesive film obtained in examples 1 to 9 and comparative examples 1 and 2, and a polyimide substrate (KAPTON 200H, 50 μmt, manufactured by tokyo corporation) was bonded to both surfaces of the adhesive layer while heating to 70 ℃. The adhesive layer was cured by hot pressing at 190 ℃ under 3MPa for 1 hour, and then cut into a width of 1cm to obtain a test piece.

T-peeling was performed at a peeling speed of 20mm/min by a tensile tester (UCT-500, manufactured by ORIENTEC) to measure the adhesive strength.

The adhesiveness was evaluated by designating the case where the adhesive strength was 3.4N/cm or more as "○", the case where the adhesive strength was 2.0N/cm or more and less than 3.4N/cm as "△", and the case where the adhesive strength was less than 2.0N/cm as "X".

(Heat resistance (glass transition temperature))

The PET film was peeled from the adhesive film obtained in examples 1 to 9 and comparative examples 1 and 2, and laminated to a thickness of 500 μm using a laminator. The obtained laminated film was cured by heating at 190 ℃ for 30 minutes to produce a cured product. The obtained cured product was heated from 0 ℃ to 300 ℃ under the conditions of a load of 5g, a heating rate of 10 ℃/min and a sample length of 1cm using a thermomechanical analyzer ("TMA/SS-6000", manufactured by Hitachi high-tech "), and the inflection point of the SS curve obtained at this time was determined as the glass transition temperature.

(Heat resistance (5% weight loss temperature))

The PET film was peeled from the adhesive film obtained in examples 1 to 9 and comparative examples 1 and 2, and laminated to a thickness of 500 μm using a laminator. The obtained laminated film was cured by heating at 190 ℃ for 30 minutes to produce a cured product.

The obtained cured product was measured for a 5% weight loss temperature under a temperature range of 30 to 500 ℃ and a temperature rise of 10 ℃/min using a thermogravimetry apparatus (manufactured by Hitachi high tech Co., Ltd. "TG/DTA 6200").

(Heat resistance (Long-term Heat resistance))

The test piece obtained in the same manner as in the "adhesiveness" was subjected to a heat treatment at 175 ℃ for 1000 hours. The adhesion force of the test piece after the heat treatment was measured by the same measurement method as the above "(adhesiveness)".

The heat resistance (long-term heat resistance) was evaluated by designating the case where the adhesive strength was 3.4N/cm or more as "○", the case where the adhesive strength was 2.0N/cm or more and less than 3.4N/cm as "△", and the case where the adhesive strength was less than 2.0N/cm as "X".

(bending resistance)

A pattern of a bending resistance test sample disclosed in JIS C6471 was formed on a polyimide flexible copper-clad substrate, and the resultant was heat-pressure bonded to a cover film obtained in examples 1 to 9 and comparative examples 1 and 2 at 190 ℃ under 3MPa for 1 hour to obtain a test piece.A change in resistance was measured under conditions of a vibration number of 1500cpm, a stroke of 20mm, a curvature of 2.5mmR, and the outside of the cover layer using an FPC high-speed bending tester (manufactured by shin-Etsu engineering Co., Ltd.).

[ Table 1]

[ Table 2]

Synthesis example 2-1 (preparation of imide oligomer 2-A)

29.2 parts by weight of 1, 3-bis (3-aminophenoxy) benzene (manufactured by Mitsui chemical industries, Ltd., "APB-N") was dissolved in 200 parts by weight of N-methylpyrrolidone (manufactured by Fuji film and Wako pure chemical industries, Ltd.). To the obtained solution, 62.0 parts by weight of 4, 4' -oxydiphthalic dianhydride (manufactured by Tokyo chemical industries, Ltd.) was added, and the mixture was stirred at 25 ℃ for 2 hours to cause a reaction, thereby obtaining an amic acid oligomer solution. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, imide oligomer 2-A (95.0% imidization) was obtained by heating at 300 ℃ for 2 hours.

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 2-A comprises as a main component an imide oligomer represented by the formula (6) (X is a 4-valent group represented by the formula (7-2), Y is a 2-valent group represented by the formula (8-2) (Z is a 2-valent group having an aromatic ring represented by the following formula (18)). Further, the softening point of imide oligomer 2-A was 138 ℃.

[ solution 18]

In formula (18), ＊ represents a bonding site.

Synthesis example 2-2 (preparation of imide oligomer 2-B)

5.4 parts by weight of 1, 3-phenylenediamine (manufactured by Tokyo chemical industry Co., Ltd., "1, 3-PDA") was dissolved in 200 parts by weight of N-methylpyrrolidone. To the obtained solution, 52.0 parts by weight of 4, 4 '- (4, 4' -isopropylidenediphenoxy) diphthalic anhydride (manufactured by Tokyo chemical Co., Ltd.) was added, and the mixture was stirred at 25 ℃ for 2 hours to cause a reaction, thereby obtaining an amic acid oligomer solution. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, imide oligomer 2-B (imidization rate 93%) was obtained by heating at 300 ℃ for 2 hours.

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 2-B is an imide oligomer represented by the formula (6) (X is a group having a valence of 4 represented by the formula (7-3), and Y is a group having a valence of 2 represented by the formula (8-4) (R)¹¹～R¹⁴Hydrogen atom)) as a main component. Further, the softening point of imide oligomer 2-B was 146 ℃.

Synthesis example 2-3 (preparation of imide oligomer 2-C)

Imide oligomer 2-C (94% imidization) was obtained in the same manner as in Synthesis example 2-2, except that 5.4 parts by weight of 1, 3-phenylenediamine was changed to 5.4 parts by weight of 1, 4-phenylenediamine ("1, 4-PDA", Tokyo chemical industry Co., Ltd.).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: imide oligomer 2-C an imide oligomer represented by the formula (6) (X is a group having a valence of 4 represented by the formula (7-3) and Y is a group having a valence of 2 represented by the formula (8-3) (R)⁷～R¹⁰Hydrogen atom)) as a main component. Further, the softening point of the imide oligomer 2-C was 151 ℃.

Synthesis examples 2 to 4 (preparation of imide oligomer 2-D)

Imide oligomer 2-D (imidization rate 95%) was obtained in the same manner as in Synthesis example 2-2, except that 5.4 parts by weight of 1, 3-phenylenediamine was changed to 12.4 parts by weight of 4, 4' -diaminodiphenyl sulfone ("DDPS" manufactured by Tokyo chemical industry Co., Ltd.).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 2-D comprises as a main component an imide oligomer represented by the formula (6) (X is a 4-valent group represented by the formula (7-3), Y is a 2-valent group represented by the formula (8-1) (Z is a sulfonyl group)). Further, the softening point of imide oligomer 2-D was 147 ℃.

Synthesis examples 2 to 5 (preparation of imide oligomer 2 to E)

Imide oligomer 2-E (imidization rate 97%) was obtained in the same manner as in Synthesis example 2-2 except that 5.4 parts by weight of 1, 3-phenylenediamine was changed to 21.6 parts by weight of bis (4- (3-aminophenoxy) phenyl) sulfone ("BAPS" manufactured by Tokyo chemical industries, Ltd.).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 2-E comprises as a main component an imide oligomer represented by the formula (6) (X is a 4-valent group represented by the formula (7-3), Y is a 2-valent group represented by the formula (8-2) (Z is a 2-valent group having an aromatic ring represented by the following formula (19)). Further, the softening point of imide oligomer 2-E was 147 ℃.

[ solution 19]

In formula (19), ＊ represents a bonding site.

Synthesis examples 2 to 6 (preparation of imide oligomer 2-F)

Imide oligomer 2-F (94% imidization) was obtained in the same manner as in Synthesis example 2-2, except that 5.4 parts by weight of 1, 3-phenylenediamine was changed to 14.6 parts by weight of 1, 3-bis (4-aminophenoxy) benzene ("TPE-R", manufactured by Tokyo chemical industries, Ltd.).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 2-F has as a main component an imide oligomer represented by the formula (6) (X is a 4-valent group represented by the formula (7-3), Y is a 2-valent group represented by the formula (8-1) (Z is a 2-valent group having an aromatic ring represented by the formula (18)). Further, the softening point of the imide oligomer 2-F was 137 ℃.

Synthesis examples 2 to 7 (preparation of imide oligomer 2 to G)

Imide oligomer 2-G (imidization rate 98%) was obtained in the same manner as in Synthesis example 2-2, except that 5.4 parts by weight of 1, 3-phenylenediamine was changed to 8.9 parts by weight of diethyltoluenediamine ("Ethacure 100", manufactured by ALBEMARLE).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: imide oligomer 2-G the imide oligomer represented by the formula (6) (X is a group having a valence of 4 represented by the formula (7-3) and Y is a group having a valence of 2 represented by the formula (8-4) (R)¹¹And R¹²In (1)One is methyl and the other is ethyl, R¹³Is a hydrogen atom, R¹⁴Ethyl group) as a main component. Further, the softening point of the imide oligomer 2 to G was 150 ℃.

Synthesis examples 2 to 8 (preparation of imide oligomer 2-H)

Imide oligomer 2-H (imidization rate 95%) was obtained in the same manner as in Synthesis example 2-1, except that 29.2 parts by weight of 1, 3-bis (3-aminophenoxy) benzene was changed to 17.8 parts by weight of diethyltoluenediamine.

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: imide oligomer 2-H an imide oligomer represented by the formula (6) (X is a group having a valence of 4 represented by the formula (7-2), Y is a group having a valence of 2 represented by the formula (8-4) (R)¹¹And R¹²One of them is methyl and the other is ethyl, R¹³Is a hydrogen atom, R¹⁴Ethyl group) as a main component. Further, the softening point of imide oligomer 2-H was 183 ℃.

Synthesis examples 2 to 9 (preparation of imide oligomer 2-I)

Imide oligomer 2-I (imidization rate 95%) was obtained in the same manner as in Synthesis example 2-2, except that 5.4 parts by weight of 1, 3-phenylenediamine was changed to 9.9 parts by weight of 4, 4' -diaminodiphenylmethane ("DDM" manufactured by Tokyo chemical industry Co., Ltd.).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 2-I comprises as a main component an imide oligomer represented by the formula (6) (X is a 4-valent group represented by the formula (7-3), Y is a 2-valent group represented by the formula (8-1) (Z is a methylene group)). Further, the softening point of imide oligomer 2-1 was 147 ℃.

Synthesis examples 2 to 10 (preparation of imide oligomer 2 to J)

Imide oligomer 2-J (imidization rate 96%) was obtained in the same manner as in Synthesis example 2-1, except that 29.2 parts by weight of 1, 3-bis (3-aminophenoxy) benzene was changed to 19.8 parts by weight of 4, 4 ' -diaminodiphenylmethane and 62.0 parts by weight of 4, 4 ' -oxybisphthalic dianhydride was changed to 58.8 parts by weight of 4, 4 ' -biphenyldicarboxylic anhydride.

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 2-J comprises, as a main component, an imide oligomer in which a portion corresponding to X in the formula (6) is a biphenyl skeleton and a portion corresponding to Y is a 2-valent group represented by the formula (8-1) (Z is a methylene group). Further, the softening point of the imide oligomer 2-J exceeds 300 ℃.

Synthesis examples 2 to 11 (preparation of imide oligomer 2-K)

Imide oligomer 2-K (imidization rate 97%) was obtained in the same manner as in Synthesis example 2-2, except that 5.4 parts by weight of 1, 3-phenylenediamine was changed to 7.7 parts by weight of norbornanediamine ("NBDA" manufactured by Mitsui chemical Co., Ltd.).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 2-K is composed mainly of an imide oligomer of the formula (6) wherein the moiety corresponding to X is a group having a valence of 4 represented by the formula (7-3) and the moiety corresponding to Y is a norbornane skeleton. Further, the softening point of imide oligomer 2-K was 137 ℃.

Synthesis examples 2 to 12 (preparation of imide oligomer 2-L)

Imide oligomer 2-L (94% imidization) was obtained in the same manner as in Synthesis example 2-1, except that 62.0 parts by weight of 4, 4 ' -oxybisphthalic dianhydride was changed to 26.0 parts by weight of 4, 4 ' - (4, 4 ' -isopropylidenediphenoxy) diphthalic anhydride.

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 2 to L have as a main component an imide oligomer represented by the following formula (20). The softening point of imide oligomer 2-L was 132 ℃.

[ solution 20]

(examples 10 to 20, comparative examples 3 to 7)

The respective materials were mixed with stirring at the mixing ratios shown in tables 3 and 4 to prepare curable resin compositions of examples 10 to 20 and comparative examples 3 to 7.

< evaluation >

The following evaluations were made for each of the curable resin compositions obtained in examples 10 to 20 and comparative examples 3 to 7. The results are shown in tables 3 and 4.

(storage stability)

The initial viscosity immediately after production and the viscosity after 24 hours storage at 25 ℃ were measured for each of the curable resin compositions obtained in examples 10 to 20 and comparative examples 3 to 7, and storage stability was evaluated by designating the viscosity change rate (viscosity after 24 hours storage at 25 ℃)/(initial viscosity) as the viscosity change rate, designating the viscosity change rate as "○" when the viscosity change rate was less than 1.5, "△" when the viscosity change rate was 1.5 or more and less than 2.0, and designating the viscosity change rate as "x" when the viscosity change rate was 2.0 or more.

The viscosity of the curable resin composition was measured using an E-type viscometer (manufactured by Toyobo industries, Ltd. "TPE-100") at 25 ℃ and a rotation speed of 5 rpm.

(coefficient of linear expansion and glass transition temperature)

Each of the curable resin compositions obtained in examples 10 to 20 and comparative examples 3 to 7 was coated on a release PET film and dried to obtain an adhesive film. The PET film was peeled from the adhesive film thus obtained, followed by lamination, followed by curing by heating at 190 ℃ for 1 hour to prepare a cured product having a thickness of 400 μm.

The obtained cured product was heated from 0 ℃ to 300 ℃ under a load of 5g, a heating rate of 10 ℃/min and a sample length of 1cm using a thermomechanical analyzer ("TMA/SS-6000", manufactured by Hitachi high-tech Co., Ltd.), and then once cooled and again heated from 0 ℃ to 300 ℃ under the same conditions. Based on the data of the temperature and dimensional change obtained in the 2 nd measurement, the average linear expansion coefficient in the temperature range of 40 ℃ to 80 ℃ was obtained as the linear expansion coefficient of the sample. The inflection point of the graph showing the relationship between the temperature and the dimensional change obtained in the 2 nd measurement was obtained as the glass transition temperature.

(5% weight loss temperature)

Each of the curable resin compositions obtained in examples 10 to 20 and comparative examples 3 to 7 was coated on a release PET film and dried to obtain an adhesive film. The PET film was peeled from the adhesive film obtained and cured by heating at 190 ℃ for 1 hour to prepare a cured product.

(initial adhesiveness)

Each of the curable resin compositions obtained in examples 10 to 20 and comparative examples 3 to 7 was coated on a release PET film so that the thickness thereof became about 20 μm, and then dried, thereby obtaining an adhesive film. The PET film was peeled off from the adhesive film, and a polyimide substrate (manufactured by Toledo DuPont, KAPTON 200H, 50 μmt) was bonded to both surfaces of the adhesive layer while heating to 70 ℃ using a laminator. The adhesive layer was cured by hot pressing at 190 ℃ under 3MPa for 1 hour, and then cut into a width of 1cm to obtain a test piece.

The initial adhesiveness was evaluated by designating the case where the adhesive strength was 3.4N/cm or more as "○", the case where the adhesive strength was 2.0N/cm or more and less than 3.4N/cm as "△", and the case where the adhesive strength was less than 2.0N/cm as "x".

(Long term Heat resistance)

The test piece obtained in the same manner as in the above "(initial adhesiveness)" was subjected to a heat treatment at 175 ℃ for 1000 hours. The heat-treated test piece was subjected to T-peeling at a peeling speed of 20mm/min using a tensile tester (manufactured by ORIENTEC, UCT-500) to measure the adhesive strength.

The long-term heat resistance was evaluated by designating the case where the adhesive strength was 3.4N/cm or more as "○", the case where the adhesive strength was 2.0N/cm or more and less than 3.4N/cm as "△", and the case where the adhesive strength was less than 2.0N/cm as "x".

[ Table 3]

[ Table 4]

Synthesis example 3-1 (preparation of imide oligomer 3-A)

10 parts by weight of 4, 4' -diaminodiphenyl ether ("DDPE" manufactured by Tokyo chemical industry Co., Ltd.) was dissolved in 200 parts by weight of N-methylpyrrolidone (manufactured by Fuji film and Wako pure chemical industries, Ltd.). To the obtained solution, 52.0 parts by weight of 4, 4 '- (4, 4' -isopropylidenediphenoxy) diphthalic anhydride (manufactured by Tokyo chemical Co., Ltd.) was added, and the mixture was stirred at 25 ℃ for 2 hours to cause a reaction, thereby obtaining an amic acid oligomer solution. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, the resulting solution was heated at 300 ℃ for 2 hours to obtain imide oligomer 3-A (imidization rate: 92%).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 3-A contains an imide oligomer represented by the following formula (21) as a main component. The imide oligomer 3-A had a softening point of 147 ℃ and a melting point of 168 ℃.

[ solution 21]

Synthesis example 3-2 (preparation of imide oligomer 3-B)

Imide oligomer 3-B (imidization rate 95%) was obtained in the same manner as in Synthesis example 3-1, except that 10 parts by weight of 4, 4' -diaminodiphenyl ether was changed to 5.4 parts by weight of 1, 4-phenylenediamine ("1, 4-PDA", manufactured by Tokyo chemical industry Co., Ltd.).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 3-B contains an imide oligomer represented by the following formula (22) as a main component. Furthermore, imide oligomerizationThe softening point of the product 3-B was 151 ℃ and the melting point was 168 ℃.

[ solution 22]

Synthesis example 3-3 (preparation of imide oligomer 3-C)

21.6 parts by weight of bis (4- (3-aminophenoxy) phenyl) sulfone (manufactured by Tokyo chemical industry Co., Ltd., "BAPS") was dissolved in 200 parts by weight of N-methylpyrrolidone. To the obtained solution, 31.0 parts by weight of 4, 4' -oxydiphthalic dianhydride (manufactured by Tokyo chemical industries, Ltd.) was added, and the mixture was stirred at 25 ℃ for 2 hours to cause a reaction, thereby obtaining an amic acid oligomer solution. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, the resulting amic acid oligomer solution was heated at 300 ℃ for 2 hours to obtain imide oligomer 3-C (98% imidization).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 3-C contains an imide oligomer represented by the following formula (23) as a main component. The imide oligomer 3-C had a softening point of 166 ℃ and a melting point of 181 ℃.

[ solution 23]

Synthesis examples 3 to 4 (preparation of imide oligomer 3-D)

17.2 parts by weight of 1, 4-bis (2- (4-aminophenyl) -2-propyl) benzene (manufactured by Mitsui chemical industries, Ltd., "BISANILINE P") was dissolved in 200 parts by weight of N-methylpyrrolidone. To the resulting solution, 32.2 parts by weight of 4, 4' -carbonyldiphthalic dianhydride (manufactured by Tokyo chemical industries, Ltd.) was added, and the mixture was stirred at 25 ℃ for 2 hours to react, thereby obtaining an amic acid oligomer solution. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, the resulting solution was heated at 300 ℃ for 2 hours to obtain imide oligomer 3-D (imidization rate 96%).

By the way of illustration¹H-NMR, GPC and FT-IR spectroscopyAnd analyzed to confirm that: the imide oligomer 3-D has an imide oligomer represented by the following formula (24) as a main component. The imide oligomer 3-D had a softening point of 228 ℃ and a melting point of 273 ℃.

[ solution 24]

Synthesis examples 3 to 5 (preparation of imide oligomer 3-E)

12.9 parts by weight of 4, 4 '-diamino-3, 3' -dihydroxybiphenyl (manufactured by Tokyo chemical industry Co., Ltd.) was dissolved in 200 parts by weight of N-methylpyrrolidone (manufactured by Fuji film and Wako pure chemical industries, Ltd.). To the resulting solution, 52.0 parts by weight of 4, 4 '- (4, 4' -isopropylidenediphenoxy) diphthalic anhydride was added, and the mixture was stirred at 25 ℃ for 2 hours to cause a reaction, thereby obtaining a solution of amic acid oligomer (a). After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, the resulting amic acid oligomer solution was heated at 300 ℃ for 2 hours to obtain an imide oligomer having an acid anhydride group at the terminal (95% imidization).

Then, 61.6 parts by weight of the obtained imide oligomer was weighed and dissolved in 200 parts by weight of N-methylpyrrolidone, 10.9 parts by weight of 3-aminophenol (manufactured by Tokyo chemical industry Co., Ltd.) was added thereto, and the mixture was stirred at 25 ℃ for 2 hours to react therewith, thereby obtaining a solution of the amic acid oligomer (B). After removing N-methylpyrrolidone from the obtained solution of amic acid oligomer (B) under reduced pressure, imide oligomer 3-E (imidization rate 93%) was obtained by heating at 300 ℃ for 2 hours.

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 3-E has an imide oligomer represented by the following formula (25) as a main component. The imide oligomer 3-E had a softening point of 198 ℃ and a melting point of 223 ℃.

[ solution 25]

Synthesis examples 3 to 6 (preparation of imide oligomer 3-F)

Imide oligomer 3-F (94% imidization) was obtained in the same manner as in Synthesis example 3-1, except that 10 parts by weight of 4, 4' -diaminodiphenyl ether was changed to 17.2 parts by weight of 1, 3-bis (2- (4-aminophenyl) -2-propyl) benzene (manufactured by Mitsui chemical Co., Ltd. "BISANILINE M").

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 3-F has an imide oligomer represented by the following formula (26) as a main component. The imide oligomer 3-F had a softening point of 145 ℃ and a melting point of 158 ℃.

[ solution 26]

Synthesis examples 3 to 7 (preparation of imide oligomer 3-G)

10.9 parts by weight of 3-aminophenol was dissolved in 200 parts by weight of N-methylpyrrolidone. To the resulting solution, 26.0 parts by weight of 4, 4 '- (4, 4' -isopropylidenediphenoxy) diphthalic anhydride was added, and the mixture was stirred at 25 ℃ for 2 hours to react, thereby obtaining an amic acid oligomer solution. After removing N-methylpyrrolidone from the obtained amic acid oligomer solution under reduced pressure, the resulting amic acid oligomer solution was heated at 300 ℃ for 2 hours to obtain imide oligomer 3-G (95% imidization).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 3 to G has an imide oligomer represented by the following formula (27) as a main component. The imide oligomer 3-G had a softening point of 137 ℃ and a melting point of 155 ℃.

[ solution 27]

Synthesis examples 3 to 8 (preparation of imide oligomer 3-H)

Imide oligomer 3-H (imidization rate 95%) was obtained in the same manner as in Synthesis example 3-1, except that 10 parts by weight of 4, 4' -diaminodiphenyl ether was changed to 5.4 parts by weight of 1, 3-phenylenediamine ("1, 3-PDA", manufactured by Tokyo chemical industry Co., Ltd.).

By the way of illustration¹H-NMR, GPC and FT-IR analyses confirmed that: the imide oligomer 3-H has an imide oligomer represented by the formula (28) as a main component. The imide oligomer 3-H had a softening point of 146 ℃ and a melting point of 163 ℃.

[ solution 28]

(examples 21 to 31, comparative examples 8 and 9)

The imide oligomers 3-A to 3-H obtained in Synthesis examples 3-1 to 3-8 were pulverized by a jet mill and then mixed with methyl ethyl ketone to obtain a mixed solution (the average particle diameter of each imide oligomer was 4 to 10 μm). The imide oligomers 3-A to 3-E and 3-H were insoluble in methyl ethyl ketone, but the imide oligomers 3-F and 3-G were soluble in methyl ethyl ketone. Next, the obtained mixed solution was mixed with other materials under stirring so that the respective materials were in the mixing ratios shown in table 5, thereby producing the curable resin compositions of examples 21 to 31 and comparative examples 8 and 9.

The dispersion state of the imide oligomer at 25 ℃ was confirmed by observation with an optical microscope for each of the obtained curable resin compositions. As a result, it was confirmed that: in each of the curable resin compositions of examples 21 to 31 using the imide oligomers 3-A to 3-E and 3-H, the imide oligomer was dispersed in a solid particle form. On the other hand, it was confirmed that: in each of the curable resin compositions of comparative examples 8 and 9 using only the imide oligomer 3-F or 3-G, the imide oligomer was dissolved.

< evaluation >

The following evaluations were made for each of the curable resin compositions obtained in examples 21 to 31 and comparative examples 8 and 9. The results are shown in Table 5.

(flexibility)

Each of the curable resin compositions obtained in examples 21 to 31 and comparative examples 8 and 9 was coated on a release PET film and dried to obtain an adhesive film. The adhesive film thus obtained was subjected to a 5mm diameter winding test in which the adhesive film was wound around a cylinder having a diameter of 5mm at 25 ℃ to confirm cracking or chipping of the adhesive film. In addition, a 180-degree bending test was performed to bend the obtained adhesive film by 180 degrees, and cracks and defects of the adhesive film were confirmed.

Flexibility was evaluated by designating "○" as the case where neither of the 5mm diameter winding test and the 180 degree bend test was cracked or broken, designating "△" as the case where no crack or break was generated in the 5mm diameter winding test but crack or break was generated in the 180 degree bend test, and designating "x" as the case where crack or break was generated in both tests.

(processability)

Each of the curable resin compositions obtained in examples 21 to 31 and comparative examples 8 and 9 was applied to a release film and dried to obtain an adhesive film. The adhesive film obtained was subjected to punching with a THOMPSON blade to confirm the state of the fracture surface and the presence or absence of powder falling.

The workability was evaluated by designating the case where the fracture surface was smooth and no chipping was observed as "○", and the case where the fracture surface was not smooth and chipping was observed as "x".

(adhesiveness)

Each of the curable resin compositions obtained in examples 21 to 31 and comparative examples 8 and 9 was coated on a release PET film so that the thickness thereof became about 20 μm, and then dried, thereby obtaining an adhesive film. The PET film was peeled off from the adhesive film, and a polyimide substrate (manufactured by Toledo DuPont, KAPTON 200H, 50 μmt) was bonded to both surfaces of the adhesive layer while heating to 70 ℃ using a laminator. The adhesive layer was cured by hot pressing at 190 ℃ under 3MPa for 1 hour, and then cut into a width of 1cm to obtain a test piece.

The adhesion was evaluated by designating the case where the adhesion was 6.0N or more as "◎", the case where the adhesion was 3.4N/cm or more and less than 6.0N/cm as "○", the case where the adhesion was 2.0N/cm or more and less than 3.4N/cm as "△", and the case where the adhesion was less than 2.0N/cm as "x".

(Heat resistance (glass transition temperature))

Each of the curable resin compositions obtained in examples 21 to 31 and comparative examples 8 and 9 was coated on a release PET film and dried to obtain a curable resin composition film. The PET film was peeled from the obtained curable resin composition film, laminated using a laminator, and then cured by heating at 190 ℃ for 1 hour to prepare a cured product having a thickness of 500. mu.m. The obtained cured product was heated from 0 ℃ to 300 ℃ under a load of 5g, a heating rate of 10 ℃/min and a sample length of 1cm using a thermomechanical analyzer ("TMA/SS-6000", manufactured by Hitachi high-tech Co., Ltd.), and the inflection point of the SS curve obtained at this time was determined as the glass transition temperature.

(Heat resistance (5% weight loss temperature))

Each of the curable resin compositions obtained in examples 21 to 31 and comparative examples 8 and 9 was applied to a release film and dried to obtain an adhesive film. The adhesive film thus obtained was cured by heating at 190 ℃ for 1 hour to prepare a cured product.

[ Table 5]

Industrial applicability

Claims

1. A curable resin composition comprising a thermosetting resin, a thermoplastic resin and an imide oligomer,

the imide oligomer has a reactive functional group capable of reacting with the thermosetting resin.

2. The curable resin composition according to claim 1, wherein the thermosetting resin contains an epoxy resin.

3. The curable resin composition according to claim 1 or 2, wherein the thermoplastic resin contains a phenoxy resin.

4. The curable resin composition according to claim 1, 2 or 3, wherein the thermoplastic resin is contained in an amount of 1 part by weight or more and 60 parts by weight or less based on 100 parts by weight of the total of the thermosetting resin, the thermoplastic resin and the imide oligomer.

5. The curable resin composition according to claim 1, 2, 3 or 4, wherein the reactive functional group is an acid anhydride group and/or a phenolic hydroxyl group.

6. The curable resin composition according to claim 1, 2, 3, 4 or 5, wherein the imide oligomer has an imidization ratio of 70% or more.

7. The curable resin composition according to claim 1, 2, 3, 4, 5 or 6, wherein the minimum melt viscosity is 5 kPa-s or more and 300 kPa-s or less.

8. An adhesive comprising the curable resin composition according to claim 1, 2, 3, 4, 5, 6 or 7.

9. A cured product of the curable resin composition according to claim 1, 2, 3, 4, 5, 6 or 7.

10. An adhesive film comprising the adhesive according to claim 8.

11. An overcoat film comprising an insulating film and an adhesive layer comprising the cured product according to claim 9.

12. A flexible printed wiring board having the coverlay film of claim 11.

13. A curable resin composition comprising a curable resin, an imide oligomer and a curing accelerator,

the imide oligomer is represented by the following formula (6),

in the formula (6), X is a 4-valent group represented by the following formula (7-1), (7-2) or (7-3), Y is a 2-valent group represented by the following formula (8-1), (8-2), (8-3) or (8-4),

in the formulae (7-1) to (7-3), ＊ represents a bonding position, and the hydrogen atoms of the aromatic rings in the formulae (7-1) to (7-3) are optionally substituted,

in the formulae (8-1) and (8-2), Z is a bond, an oxygen atom, a sulfonyl group, a linear or branched 2-valent hydrocarbon group optionally having an oxygen atom at the bonding position, or a 2-valent group having an aromatic ring optionally having an oxygen atom at the bonding position, the hydrogen atom of the aromatic ring in the formulae (8-1) and (8-2) is optionally substituted,

in the formulae (8-3) and (8-4), R⁷～R¹⁴Represents a hydrogen atom or a 1-valent hydrocarbon group, each of which may be the same or different;

in the formulae (8-1) to (8-4), ＊ represents a bonding site.

14. The curable resin composition according to claim 13, wherein the curable resin contains an epoxy resin.

15. The curable resin composition according to claim 13 or 14, wherein the imide oligomer has a softening point of 250 ℃ or lower.

16. The curable resin composition according to claim 13, 14 or 15, wherein the imide oligomer has an imidization ratio of 70% or more.

17. The curable resin composition according to claim 13, 14, 15 or 16, wherein the curing accelerator is a basic catalyst.

18. The curable resin composition according to claim 13, 14, 15, 16 or 17, wherein the curing accelerator has an imidazole skeleton.

19. The curable resin composition according to claim 13, 14, 15, 16, 17 or 18, wherein the content of the curing accelerator is 0.8 parts by weight or more and 10 parts by weight or less based on 100 parts by weight of the total of the curable resin, the imide oligomer and the curing accelerator.

20. A cured product of the curable resin composition according to claim 13, 14, 15, 16, 17, 18 or 19.

21. The cured product according to claim 20, wherein the average linear expansion coefficient in a temperature range of 40 ℃ to 80 ℃ is 60ppm or less.

22. An adhesive comprising the curable resin composition according to claim 13, 14, 15, 16, 17, 18 or 19.

23. An adhesive film comprising the curable resin composition according to claim 13, 14, 15, 16, 17, 18 or 19.

24. A curable resin composition comprising a curable resin and an imide oligomer,

the curable resin is in a liquid state at 25 ℃,

the imide oligomer was dispersed in the form of solid particles at 25 ℃.

25. The curable resin composition according to claim 24, wherein the curable resin contains an epoxy resin.

26. The curable resin composition according to claim 24 or 25, wherein the imide oligomer has a reactive functional group capable of reacting with the curable resin.

27. The curable resin composition according to claim 26, wherein the reactive functional group is an acid anhydride group and/or a phenolic hydroxyl group.

28. The curable resin composition according to claim 24, 25, 26 or 27, wherein the imide oligomer has a softening point of 250 ℃ or lower.

29. The curable resin composition according to claim 24, 25, 26, 27 or 28, wherein the imide oligomer has an imidization ratio of 70% or more.

30. The curable resin composition according to claim 24, 25, 26, 27, 28 or 29, wherein the imide oligomer contains an imide oligomer insoluble in the curable resin composition at 25 ℃ and an imide oligomer soluble in the curable resin composition at 25 ℃.

31. The curable resin composition according to claim 30, wherein the content of the imide oligomer soluble in the curable resin composition at 25 ℃ is 80 parts by weight or less based on 100 parts by weight of the imide oligomer as a whole.

32. A cured product of the curable resin composition according to claim 24, 25, 26, 27, 28, 29, 30 or 31.

33. An adhesive comprising the curable resin composition of claim 24, 25, 26, 27, 28, 29, 30 or 31.

34. An adhesive film comprising the adhesive according to claim 33.