Curable resin composition, cured product, adhesive, and adhesive film

Abstract

To provide a curable resin composition having excellent handleability before curing while having excellent reliability after curing, a cured product of the curable resin composition, and an adhesive and an adhesive film each including the curable resin composition.SOLUTION: A curable resin composition includes a curable resin, a curing agent, and an inorganic filler. A pre-cured film product thereof with a thickness of 150 μm has an elongation at break of 50% or more, and a cured product thereof has a tensile storage elastic modulus of 2 GPa or more at 150°C.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a curable resin composition. The present invention also relates to a cured product of the curable resin composition, and an adhesive and an adhesive film made using the curable resin composition. [Background technology]

[0002] In recent years, the use of flexible printed circuit boards (FPCs) has expanded to include in-vehicle applications, and adhesives used in FPCs and coverlay films that protect FPCs are required to have high heat resistance. For such adhesives, curable resin compositions using curable resins such as epoxy resins that have low shrinkage and excellent adhesion, insulating properties, and chemical resistance are used. In particular, there is a demand for curable resin compositions that provide good results in solder reflow tests and long-term heat resistance tests that evaluate short-term heat resistance. Patent Documents 1 and 2, for example, disclose curable resin compositions that contain an epoxy resin and an imide compound as a curing agent, as curable resin compositions with excellent heat resistance and adhesion. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 61-270852 [Patent Document 2] Special Publication No. 2004-502859 Summary of the Invention [Problem to be solved by the invention]

[0004] Conventional curable resin compositions, even if they have excellent short-term heat resistance and long-term heat resistance, sometimes have poor reliability, such as cracks occurring when the cured product is subjected to a temperature cycle test (TCT). To improve the reliability of the cured product, it has been considered to blend a large amount of inorganic filler into the curable resin composition or to rigidify the skeleton of the curable resin used, but the curable resin composition obtained in this way sometimes has poor flexibility and processability before curing (B stage), i.e., poor handleability. An object of the present invention is to provide a curable resin composition that has excellent handleability before curing and excellent reliability after curing, as well as a cured product of the curable resin composition, and an adhesive and an adhesive film made using the curable resin composition. [Means for solving the problem]

[0005] The present invention provides a curable resin composition containing a curable resin, a curing agent, and an inorganic filler, wherein the pre-cured film having a thickness of 150 μm has a breaking elongation of 50% or more, and the cured product has a tensile storage modulus of 2 GPa or more at 150°C. The present invention will be described in detail below.

[0006] The present inventors have investigated how to make a curable resin composition such that a film having a thickness of 150 μm before curing has a breaking elongation of a specific value or more, and a cured product has a tensile storage modulus at 150° C. of a specific value or more. As a result, they have found that the obtained curable resin composition has excellent handleability before curing (B stage) and excellent reliability after curing, which has led to the completion of the present invention.

[0007] The curable resin composition of the present invention has a lower limit of the breaking elongation of a 150 μm-thick film before curing of 50%. When the breaking elongation is 50% or more, the curable resin composition of the present invention has excellent handleability before curing (B stage). The lower limit of the breaking elongation is preferably 100%, and more preferably 200%. There is no particular preferred upper limit to the breaking elongation, but the substantial upper limit is 500%. The breaking elongation can be determined as the elongation at break when a test piece prepared using a film of the curable resin composition is pulled at a rate of 200 mm / min using a tensile tester (for example, the Tensilon Universal Tester RTI-1310 manufactured by A&D Co., Ltd.) at 25° C. The test piece for measuring the breaking elongation can be prepared by applying the curable resin composition to a substrate film, drying it to form a film having a thickness of 150 μm, and punching the resulting film into a strip having a length of 100 mm and a width of 10 mm.

[0008] The curable resin composition of the present invention has a lower limit of the tensile storage modulus of the cured product at 150°C of 2 GPa. When the cured product has a tensile storage modulus of 2 GPa or more at 150°C, the curable resin composition of the present invention can suppress the occurrence of cracks after a temperature cycle test, resulting in excellent reliability. The lower limit of the tensile storage modulus of the cured product at 150°C is preferably 2.5 GPa, more preferably 3.5 GPa. There is no particular preferred upper limit to the tensile storage modulus, but the substantial upper limit is 10 GPa. The tensile storage modulus can be measured for a cured product of the curable resin composition at 150°C using a dynamic viscoelasticity measuring device (for example, "DVA-200" manufactured by IT Measurement Co., Ltd.) under conditions of 10 Hz and 0.1% strain. The cured product for which the tensile storage modulus is to be measured can be produced by applying the curable resin composition to a substrate film, drying it to form a film having a thickness of 150 µm, and heating the obtained film at 190°C for 1 hour.

[0009] The curable resin composition of the present invention contains a curable resin. Examples of the curable resin include epoxy resin, acrylic resin, phenol resin, cyanate resin, isocyanate resin, maleimide resin, benzoxazine resin, silicone resin, and fluororesin. Among these, the curable resin preferably includes an epoxy resin. These curable resins may be used alone or in combination of two or more. Furthermore, in order to improve tackiness at room temperature and processability when processing into a film, the curable resin is preferably liquid or semi-solid at 25°C, more preferably liquid at 25°C, and even more preferably contains an epoxy resin that is liquid at 25°C.

[0010] Examples of the epoxy resin include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol E type epoxy resins, bisphenol S type epoxy resins, 2,2'-diallyl bisphenol A type epoxy resins, hydrogenated bisphenol type epoxy resins, propylene oxide-added bisphenol A type epoxy resins, triazine type epoxy resins, resorcinol type epoxy resins, biphenyl type epoxy resins, sulfide type epoxy resins, diphenyl ether type epoxy resins, dicyclopentadiene type epoxy resins, naphthalene type epoxy resins, fluorene type epoxy resins, naphthylene ether type epoxy resins, phenol novolac type epoxy resins, ortho-cresol novolac type epoxy resins, dicyclopentadiene novolac type epoxy resins, biphenyl novolac type epoxy resins, naphthalene phenol novolac type epoxy resins, glycidyl amine type epoxy resins, alkyl polyol type epoxy resins, rubber-modified epoxy resins, and glycidyl ester compounds. Among these, bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol E type epoxy resins, resorcinol type epoxy resins, and triazine type epoxy resins are preferred because they have low viscosity and make it easier to adjust the processability of the resulting curable resin composition.

[0011] The content of the curable resin is preferably 20 parts by weight at the lower limit and 45 parts by weight at the upper limit, relative to 100 parts by weight of the total of the curable resin, the curing agent, and the inorganic filler. By having the content of the curable resin in this range, the resulting curable resin composition has better handleability before curing and better reliability of the cured product. The more preferred lower limit of the content of the curable resin is 35 parts by weight, and the more preferred upper limit is 40 parts by weight.

[0012] The curable resin composition of the present invention contains a curing agent. Examples of the curing agent include an imide oligomer having an imide skeleton in the main chain and a crosslinkable functional group at the end, an acid anhydride curing agent, a phenolic curing agent, a thiol curing agent, an amine curing agent, a cyanate curing agent, an active ester curing agent, etc. Among these, from the viewpoint of the adhesiveness and long-term heat resistance of the cured product of the obtained curable resin composition, it is preferable that the curing agent contains the imide oligomer.

[0013] The imide oligomer preferably has a structure represented by the following formula (1-1) or (1-2), or the following formula (2-1) or (2-2), as the structure containing the crosslinkable functional group. By having a structure represented by the following formula (1-1) or (1-2), or the following formula (2-1) or (2-2), the imide oligomer has better reactivity and compatibility with curable resins such as epoxy resins.

[0014] [ka]

[0015] In formula (1-1) and formula (1-2), A is an acid dianhydride residue, B is an aliphatic diamine residue or an aromatic diamine residue, and in formula (1-2), Ar is an optionally substituted divalent aromatic group.

[0016] [ka]

[0017] In formula (2-1) and formula (2-2), A is an acid dianhydride residue, B is an aliphatic triamine residue or an aromatic triamine residue, and in formula (2-2), Ar is an optionally substituted divalent aromatic group.

[0018] The acid dianhydride residue is preferably an aromatic tetracarboxylic acid dianhydride residue which may be substituted, and more preferably a tetravalent group represented by the following formula (3-1) or (3-2).

[0019] [ka]

[0020] In formulas (3-1) and (3-2), * represents a bonding position, and in formula (3-1), Z represents a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched divalent hydrocarbon group, or a divalent group having an aromatic ring. When Z represents a hydrocarbon group, an oxygen atom may be present between the hydrocarbon group and each aromatic ring in formula (3-1). When Z represents a divalent group having an aromatic ring, an oxygen atom may be present between the divalent group having an aromatic ring and each aromatic ring in formula (3-1). The hydrogen atoms of the aromatic rings in formulas (3-1) and (3-2) may be substituted.

[0021] When Z in the above formula (3-1) is a linear or branched divalent hydrocarbon group or a divalent group having an aromatic ring, these groups may be substituted. When the linear or branched divalent hydrocarbon group or the divalent group having an aromatic ring is substituted, examples of the substituent include a halogen atom, a linear or branched alkyl group, a linear or branched alkenyl group, an alicyclic group, an aryl group, an alkoxy group, a nitro group, and a cyano group.

[0022] Examples of the acid dianhydride from which the acid dianhydride residue is derived include the acid dianhydride represented by the formula (7) described below.

[0023] The imide oligomer is preferably represented by the formula (1-1) or (1-2) above, wherein B is an aliphatic diamine residue having 4 or more and 30 or less carbon atoms, or represented by the formula (2-1) or (2-2) above, wherein B is an aliphatic triamine residue having 4 or more and 30 or less carbon atoms. By containing an imide oligomer having such a structure, it becomes easier to adjust the breaking elongation of a 150 μm-thick film of the obtained curable resin composition before curing and the tensile storage modulus at 150°C of the cured product to the above-mentioned ranges. The lower limit of the number of carbon atoms in the aliphatic diamine residue and the aliphatic triamine residue is preferably 5. The upper limit of the number of carbon atoms in the aliphatic diamine residue and the aliphatic triamine residue is preferably 10, and more preferably 6.

[0024] The aliphatic diamine residue having 4 to 30 carbon atoms may be linear or branched, or may have an alicyclic skeleton. Specific examples of the aliphatic diamine from which the aliphatic diamine residue having 4 to 30 carbon atoms is derived include 1,4-diaminobutane, 1,6-diaminohexane, 1,8-diaminooctane, 1,9-diaminononane, 1,10-diaminodecane, 1,11-diaminoundecane, 1,12-diaminododecane, 1,14-diaminotetradecane, 1,16-diaminohexadecane, 1,18-diaminooctadecane, 1,20-diaminoeicosane, 2 3,3'-oxybis(propylamine), 1,2-bis(2-aminoethoxy)ethane, 1,3-bis(aminomethyl)cyclohexane, 1,4-bis(aminomethyl)cyclohexane, cyclohexanediamine, methylcyclohexanediamine, and isophoronediamine.

[0025] The aliphatic triamine residue having 4 to 30 carbon atoms may be linear or branched, or may have an alicyclic skeleton. Specific examples of aliphatic triamines from which the aliphatic triamine residue having 4 to 30 carbon atoms is derived include 3,3'-diamino-N-methyldipropylamine, 3,3'-diaminodipropylamine, diethylenetriamine, bis(hexamethylene)triamine, and 2,2'-bis(methylamino)-N-methyldiethylamine.

[0026] Furthermore, if the imide oligomer has a siloxane skeleton in its structure, this may lower the glass transition temperature after curing or may contaminate the adherend, resulting in poor adhesion. Therefore, it is preferable that the imide oligomer does not have a siloxane skeleton in its structure.

[0027] The number average molecular weight of the imide oligomer is preferably 5000 or less. When the number average molecular weight of the imide oligomer is 5000 or less, the cured product of the obtained curable resin composition has better long-term heat resistance. The upper limit of the number average molecular weight of the imide oligomer is more preferably 4000, and even more preferably 3000. In particular, the number average molecular weight of the imide oligomer is preferably 900 or more and 5000 or less when it has a structure represented by the above formula (1-1) or (2-1), and is preferably 550 or more and 4000 or less when it has a structure represented by the above formula (1-2) or (2-2). When it has a structure represented by the above formula (1-1) or (2-1), the lower limit of the number average molecular weight is more preferably 950, and even more preferably 1000. When it has a structure represented by the above formula (1-2) or (2-2), the lower limit of the number average molecular weight is more preferably 580, and even more preferably 600. In this specification, the "number average molecular weight" is a value determined by gel permeation chromatography (GPC) using tetrahydrofuran as a solvent and converted into polystyrene. Examples of columns used in measuring the number average molecular weight converted into polystyrene by GPC include JAIGEL-2H-A (manufactured by Japan Analytical Industry Co., Ltd.).

[0028] Specifically, the imide oligomer is preferably an imide oligomer represented by the following formula (4-1), (4-2), (4-3), (4-4), or (4-5), or an imide oligomer represented by the following formula (5-1), (5-2), (5-3), (5-4), or (5-5).

[0029] [ka]

[0030] In formulas (4-1) to (4-5), A represents the acid dianhydride residue, and in formulas (4-1), (4-3) to (4-5), A may be the same or different. In formulas (4-1) to (4-4), B represents the aliphatic diamine residue or the aromatic diamine residue, and in formulas (4-3) and (4-4), B may be the same or different. In formula (4-5), B represents the aliphatic triamine residue or the aromatic triamine residue. In formula (4-2), X represents a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group, and in formula (4-4), W represents a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group. In formulas (4-3) and (4-4), n represents the number of repeating units.

[0031] [ka]

[0032] In formulas (5-1) to (5-5), A represents the acid dianhydride residue, and in formulas (5-1) to (5-5), A may be the same or different. In formulas (5-1) to (5-5), R represents a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group, and in formulas (5-1), (5-3), and (5-5), R may be the same or different. In formulas (5-2) and (5-4), W represents a hydrogen atom, a halogen atom, or an optionally substituted monovalent hydrocarbon group. In formulas (5-1) to (5-4), B represents the aliphatic diamine residue or the aromatic diamine residue, and in formulas (5-3) and (5-4), B may be the same or different. In formula (5-5), B is the aliphatic triamine residue or the aromatic triamine residue.

[0033] A in the above formulas (4-1) to (4-5) and (5-1) to (5-5) is preferably a tetravalent group represented by the following formula (6-1) or (6-2).

[0034] [ka]

[0035] In formulas (6-1) and (6-2), * represents a bonding position, and in formula (6-1), Z represents a bond, an oxygen atom, a carbonyl group, a sulfur atom, a sulfonyl group, a linear or branched divalent hydrocarbon group, or a divalent group having an aromatic ring. When Z represents a hydrocarbon group, an oxygen atom may be present between the hydrocarbon group and each aromatic ring in formula (6-1). When Z represents a divalent group having an aromatic ring, an oxygen atom may be present between the divalent group having an aromatic ring and each aromatic ring in formula (6-1). The hydrogen atoms of the aromatic rings in formulas (6-1) and (6-2) may be substituted.

[0036] B in the above formulas (4-1) to (4-4) and (5-1) to (5-4) is preferably an aliphatic diamine residue having 4 or more and 30 or less carbon atoms, and B in the above formulas (4-5) and (5-5) is preferably an aliphatic triamine residue having 4 or more and 30 or less carbon atoms.

[0037] Examples of methods for producing an imide oligomer having a structure represented by the above formula (1-1) include a method of reacting an acid dianhydride represented by the following formula (7) with a diamine represented by the following formula (8). Alternatively, an imide oligomer having a structure represented by the above formula (2-1) can be produced by using an aliphatic triamine or aromatic triamine instead of the diamine represented by the following formula (8).

[0038] [ka]

[0039] In formula (7), A is the same tetravalent group as A in the above formula (1-1).

[0040] [ka]

[0041] In formula (8), B is the same divalent group as B in formula (1-1), and R 1 ~R 4 are each independently a hydrogen atom or a monovalent hydrocarbon group.

[0042] A specific example of a method for reacting the acid dianhydride represented by the above formula (7) with the diamine represented by the above formula (8) is shown below. First, the diamine represented by formula (8) is dissolved in a solvent (e.g., N-methylpyrrolidone) in which the amic acid oligomer obtained by the reaction is soluble. The dianhydride represented by formula (7) is then added to the resulting solution and reacted to obtain an amic acid oligomer solution. The solvent is then removed by heating or reducing pressure, and the mixture is heated at about 200°C or higher for at least one hour to react the amic acid oligomer. By adjusting the molar ratio of the dianhydride represented by formula (7) to the diamine represented by formula (8) and the imidization conditions, an imide oligomer having the desired number-average molecular weight and the structure represented by formula (1-1) at both ends can be obtained. Furthermore, by replacing a portion of the acid dianhydride represented by the above formula (7) with the acid anhydride represented by the following formula (9), it is possible to obtain an imide oligomer having a desired number average molecular weight and having a structure represented by the above formula (1-1) at one end and a structure derived from the acid anhydride represented by the following formula (9) at the other end. In this case, the acid dianhydride represented by the above formula (7) and the acid anhydride represented by the following formula (9) may be added simultaneously or separately. Furthermore, by replacing a portion of the diamine represented by the above formula (8) with a monoamine represented by the following formula (10), it is possible to obtain an imide oligomer having a desired number average molecular weight and having a structure represented by the above formula (1-1) at one end and a structure derived from the monoamine represented by the following formula (10) at the other end. In this case, the diamine represented by the above formula (8) and the monoamine represented by the following formula (10) may be added simultaneously or separately.

[0043] [ka]

[0044] In formula (9), Ar is an optionally substituted divalent aromatic group.

[0045] [ka]

[0046] In formula (10), Ar is an optionally substituted monovalent aromatic group, and R 5 and R 6 are each independently a hydrogen atom or a monovalent hydrocarbon group.

[0047] Examples of methods for producing an imide oligomer having a structure represented by the above formula (1-2) include a method of reacting an acid dianhydride represented by the above formula (7), a diamine represented by the above formula (8), and a phenolic hydroxyl group-containing monoamine represented by the following formula (11). Also, by using an aliphatic triamine or aromatic triamine instead of the diamine represented by the above formula (8), an imide oligomer having a structure represented by the above formula (2-2) can be produced.

[0048] [ka]

[0049] In formula (11), Ar is an optionally substituted divalent aromatic group, and R 7 and R 8 are each independently a hydrogen atom or a monovalent hydrocarbon group.

[0050] A specific example of a method for reacting an acid dianhydride represented by the above formula (7), a diamine represented by the above formula (8), and a phenolic hydroxyl group-containing monoamine represented by the above formula (11) is shown below. First, the phenolic hydroxyl group-containing monoamine represented by formula (11) and the diamine represented by formula (8) are dissolved in a solvent (e.g., N-methylpyrrolidone) in which the amic acid oligomer obtained by the reaction is soluble. The dianhydride represented by formula (7) is then added to the resulting solution and reacted to obtain an amic acid oligomer solution. The solvent is then removed by heating or reducing pressure, and the mixture is heated at about 200°C or higher for at least one hour to react the amic acid oligomer. By adjusting the molar ratios of the dianhydride represented by formula (7), the diamine represented by formula (8), and the phenolic hydroxyl group-containing monoamine represented by formula (11), as well as the imidization conditions, an imide oligomer having the desired number-average molecular weight and the structure represented by formula (1-2) at both ends can be obtained. Furthermore, by replacing a portion of the phenolic hydroxyl group-containing monoamine represented by the formula (11) with the monoamine represented by the formula (10), it is possible to obtain an imide oligomer having a desired number average molecular weight and having a structure represented by the formula (1-2) at one end and a structure derived from the monoamine represented by the formula (10) at the other end. In this case, the phenolic hydroxyl group-containing monoamine represented by the formula (11) and the monoamine represented by the formula (10) may be added simultaneously or separately.

[0051] The acid dianhydride represented by the above formula (7) is preferably an aromatic tetracarboxylic acid dianhydride which may be substituted. Specific examples of the acid dianhydride represented by the above formula (7) include pyromellitic anhydride, 3,3'-oxydiphthalic anhydride, 3,4'-oxydiphthalic anhydride, 4,4'-oxydiphthalic anhydride, 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride, 4,4'-bis(2,3-dicarboxylphenoxy)diphenyl ether acid dianhydride, p-phenylenebis(trimellitate anhydride), and 2,3,3',4'-biphenyltetracarboxylic dianhydride. Among these, aromatic tetracarboxylic dianhydrides having a melting point of 240°C or less are preferred as the acid dianhydride, aromatic tetracarboxylic dianhydrides having a melting point of 220°C or less are more preferred, aromatic tetracarboxylic dianhydrides having a melting point of 200°C or less are even more preferred, and 3,4'-oxydiphthalic dianhydride (melting point 180°C) and 4,4'-(4,4'-isopropylidenediphenoxy)diphthalic anhydride (melting point 190°C) are particularly preferred, as they provide superior solubility and heat resistance. In this specification, the "melting point" refers to a value measured as the endothermic peak temperature when the temperature is increased at 10°C / min using a differential scanning calorimeter. Examples of the differential scanning calorimeter include the EXTEAR DSC6100 (manufactured by SII NanoTechnology Inc.).

[0052] The diamine represented by the above formula (8) is preferably an aliphatic diamine from which the above-mentioned aliphatic diamine residue having 4 to 30 carbon atoms is derived.

[0053] Examples of the acid anhydride represented by the above formula (9) include phthalic anhydride, 3-methylphthalic anhydride, 4-methylphthalic anhydride, 1,2-naphthalic anhydride, 2,3-naphthalic anhydride, 1,8-naphthalic anhydride, 2,3-anthracenedicarboxylic anhydride, 4-tert-butylphthalic anhydride, 4-ethynylphthalic anhydride, 4-phenylethynylphthalic anhydride, 4-fluorophthalic anhydride, 4-chlorophthalic anhydride, 4-bromophthalic anhydride, and 3,4-dichlorophthalic anhydride.

[0054] Examples of the monoamine represented by the above formula (10) include aniline, o-toluidine, m-toluidine, p-toluidine, 2,4-dimethylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 2-tert-butylaniline, 3-tert-butylaniline, 4-tert-butylaniline, 1-naphthylamine, 2-naphthylamine, 1-aminoanthracene, 2-aminoanthracene, 9-aminoanthracene, 1-aminopyrene, 3-chloroaniline, o-anisidine, m-anisidine, p-anisidine, 1-amino-2-methylnaphthalene, 2,3-dimethylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 3,4-dimethylaniline, 4-ethylaniline, 4-ethynylaniline, 4-isopropylaniline, 4-(methylthio)aniline, and N,N-dimethyl-1,4-phenylenediamine.

[0055] Examples of phenolic hydroxyl group-containing monoamines represented by the above formula (11) include 3-aminophenol, 4-aminophenol, 4-amino-o-cresol, 5-amino-o-cresol, 4-amino-2,3-xylenol, 4-amino-2,5-xylenol, 4-amino-2,6-xylenol, 4-amino-1-naphthol, 5-amino-2-naphthol, 6-amino-1-naphthol, 4-amino-2,6-diphenylphenol, etc. Among these, 4-amino-o-cresol and 5-amino-o-cresol are preferred because they are easily available and have excellent storage stability and can achieve a high glass transition temperature after curing.

[0056] When the imide oligomer is produced by the above-described production method, the imide oligomer is obtained as a mixture (imide oligomer composition) of multiple types of imide oligomers having the structure represented by formula (1-1) or multiple types of imide oligomers having the structure represented by formula (1-2) with the respective raw materials. When an aliphatic triamine or aromatic triamine is used instead of the diamine represented by formula (8), the imide oligomer is obtained as a mixture (imide oligomer composition) of multiple types of imide oligomers having the structure represented by formula (2-1) or multiple types of imide oligomers having the structure represented by formula (2-2) with the respective raw materials. Since the imide oligomer composition has an imidization rate of 70% or more, when used as a curing agent, a cured product having excellent high-temperature mechanical strength and long-term heat resistance can be obtained. The lower limit of the imidization rate of the imide oligomer composition is preferably 75%, more preferably 80%. There is no particular upper limit to the imidization rate of the imide oligomer composition, but the substantial upper limit is 98%. The "imidization rate" is measured by the attenuated total reflection (ATR) method using a Fourier transform infrared spectrophotometer (FT-IR) and is calculated based on the 1660 cm peak derived from the carbonyl group of the amic acid. -1 The absorbance of the amic acid oligomer can be calculated from the peak absorbance area around the peak absorbance area using the following formula: An example of the Fourier transform infrared spectrophotometer is the UMA600 (manufactured by Agilent Technologies). Note that the "peak absorbance area of ​​the amic acid oligomer" in the following formula refers to the absorbance area of ​​the amic acid oligomer obtained by reacting an acid dianhydride with a diamine or a phenolic hydroxyl group-containing monoamine and then removing the solvent by evaporation or the like without performing an imidization step. Imidization rate (%)=100×(1-(peak absorbance area after imidization) / (peak absorbance area of ​​amic acid oligomer))

[0057] From the viewpoint of solubility in the curable resin composition, the imide oligomer composition preferably dissolves in an amount of 3 g or more in 10 g of tetrahydrofuran at 25°C.

[0058] The preferred lower limit of the content of the curing agent per 100 parts by weight of the total of the curable resin, the curing agent, and the inorganic filler described below is 20 parts by weight, and the preferred upper limit is 40 parts by weight. When the content of the curing agent is within this range, the resulting curable resin composition has better handleability before curing and better reliability of the cured product. The more preferred lower limit of the content of the curing agent is 30 parts by weight, and the more preferred upper limit is 35 parts by weight. In addition, when the imide oligomer is used as the curing agent and the imide oligomer is contained in the imide oligomer composition described above, the content of the imide oligomer means the content of the imide oligomer composition (and, when another imide oligomer is used in combination, the total content of the imide oligomer composition and the other imide oligomer).

[0059] The curable resin composition of the present invention contains an inorganic filler. The inorganic filler preferably contains at least one selected from the group consisting of silica and barium sulfate. By containing at least one selected from the group consisting of silica and barium sulfate as the inorganic filler, the curable resin composition of the present invention has better handleability before curing.

[0060] Examples of inorganic fillers other than the silica and barium sulfate include alumina, aluminum nitride, boron nitride, silicon nitride, magnesium carbonate, barium carbonate, glass powder, glass frit, glass fiber, carbon fiber, and inorganic ion exchangers. The inorganic fillers may be used alone or in combination of two or more.

[0061] The inorganic filler has a preferred lower limit of 0.1 μm and a preferred upper limit of 1.0 μm in average particle size. By using the inorganic filler with an average particle size in this range, the resulting curable resin composition has better handleability before curing. The inorganic filler has a more preferred lower limit of 0.3 μm and a more preferred upper limit of 0.7 μm in average particle size.

[0062] The content of the inorganic filler is preferably 20 parts by weight at the lower limit and 50 parts by weight at the upper limit, relative to 100 parts by weight of the total of the curable resin, the curing agent, and the inorganic filler. By having the content of the inorganic filler in this range, the resulting curable resin composition has better handleability before curing and better reliability of the cured product. The more preferred lower limit of the content of the inorganic filler is 30 parts by weight, and the more preferred upper limit is 40 parts by weight.

[0063] The curable resin composition of the present invention preferably contains a flow control agent for the purposes of improving the ability to coat an adherend in a short time and the shape retention. Examples of the flow adjuster include fumed silica such as Aerosil, layered silicates, and the like. The flow control agents may be used alone or in combination of two or more. The flow control agent preferably has an average particle size of less than 100 nm.

[0064] When the flow control agent is contained, the content of the flow control agent in 100 parts by weight of the curable resin composition of the present invention is preferably 0.1 parts by weight at the lower limit and 50 parts by weight at the upper limit. By having the content of the flow control agent in this range, the effect of improving the coatability and shape retention on the adherend in a short time is more excellent. The content of the flow control agent is more preferably 0.5 parts by weight at the lower limit and 30 parts by weight at the upper limit. In this specification, "100 parts by weight of a curable resin composition" means 100 parts by weight of the total content of the components of the curable resin composition excluding the solvent, unless it is clearly stated as "100 parts by weight of a curable resin composition including a solvent."

[0065] The curable resin composition of the present invention may contain an organic filler for the purposes of stress relaxation, 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 these, polyamide particles, polyamideimide particles, and polyimide particles are preferred. The organic fillers may be used alone or in combination of two or more.

[0066] When the organic filler is contained, the preferred upper limit of the content of the organic filler per 100 parts by weight of the curable resin composition of the present invention is 300 parts by weight. By using 300 parts by weight or less of the organic filler, the cured product of the obtained curable resin composition will have excellent toughness and the like while maintaining excellent adhesive properties and the like. The more preferred upper limit of the content of the organic filler is 200 parts by weight, and the even more preferred upper limit is 150 parts by weight.

[0067] The curable resin composition of the present invention preferably contains a curing accelerator, which can shorten the curing time and improve productivity.

[0068] 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, etc. Among these, imidazole-based curing accelerators are preferred because of their excellent storage stability.

[0069] When the curing accelerator is contained, the content of the curing accelerator in 100 parts by weight of the curable resin composition of the present invention is preferably 0.01 parts by weight at the lower limit and 10 parts by weight at the upper limit. By having the content of the curing accelerator in this range, the curing time can be shortened while maintaining excellent adhesiveness, etc. A more preferred lower limit of the content of the curing accelerator is 0.05 parts by weight, and a more preferred upper limit is 5 parts by weight.

[0070] The curable resin composition of the present invention may contain a polymer component. The polymer component serves as a film-forming component, and further, by using the polymer component, the cured product of the curable resin composition of the present invention will have better heat resistance.

[0071] The number average molecular weight of the polymer component is preferably 3,000 at its lower limit and 100,000 at its upper limit. When the number average molecular weight of the polymer component is within this range, the curable resin composition obtained has excellent heat resistance in the cured product. The number average molecular weight of the polymer component is more preferably 5,000 at its lower limit and 80,000 at its upper limit.

[0072] Examples of the polymer component include polyimide, phenoxy resin, polyamide, polyamideimide, polymaleimide, cyanate resin, benzoxazine resin, acrylic resin, urethane resin, polyester resin, etc. Among these, from the viewpoint of heat resistance, it is preferable to include at least one selected from the group consisting of polyimide, polyamide, polyamideimide, and polymaleimide, and it is more preferable to include polyimide. The above polymer components may be used alone or in combination of two or more.

[0073] When the curable resin composition of the present invention contains the polymer component, the content of the polymer component in 100 parts by weight of the curable resin composition of the present invention is preferably 0.5 parts by weight at the lower limit and 20 parts by weight at the upper limit. When the content of the polymer component is within this range, the cured product of the obtained curable resin composition has better heat resistance. The content of the polymer component is more preferably 1 part by weight at the lower limit and 15 parts by weight at the upper limit.

[0074] The curable resin composition of the present invention may contain a flame retardant. Examples of the flame retardant include boehmite-type aluminum hydroxide, metal hydrates such as aluminum hydroxide and magnesium hydroxide, halogen-based compounds, phosphorus-based compounds, nitrogen-based compounds, etc. Among these, boehmite-type aluminum hydroxide is preferred. The flame retardants may be used alone or in combination of two or more.

[0075] When the flame retardant is contained, the content of the flame retardant in 100 parts by weight of the curable resin composition of the present invention is preferably 5 parts by weight at the lower limit and 200 parts by weight at the upper limit. When the content of the flame retardant is within this range, the cured product of the curable resin composition obtained has excellent flame retardancy while maintaining excellent adhesive properties, etc. The content of the flame retardant is more preferably 10 parts by weight at the lower limit and 150 parts by weight at the upper limit.

[0076] The curable resin composition of the present invention may contain a solvent from the viewpoint of coatability and the like. The solvent is preferably one having a boiling point of less than 200° C. from the viewpoints of coatability and storage stability. Examples of the solvent having a boiling point of less than 200° C. include alcohol-based solvents, ketone-based solvents, ester-based solvents, hydrocarbon-based solvents, halogen-based solvents, ether-based solvents, and nitrogen-containing solvents. Examples of the alcohol solvent include methanol, ethanol, isopropyl alcohol, normal propyl alcohol, isobutyl alcohol, normal butyl alcohol, tertiary butyl alcohol, and 2-ethylhexanol. Examples of the ketone solvent include acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl propyl ketone, diisobutyl ketone, cyclohexanone, methylcyclohexanone, and diacetone alcohol. Examples of the ester solvent include methyl acetate, ethyl acetate, butyl acetate, isobutyl acetate, methoxybutyl acetate, amyl acetate, normal propyl acetate, isopropyl acetate, methyl lactate, ethyl lactate, and butyl lactate. Examples of the hydrocarbon solvent include benzene, toluene, xylene, normal hexane, isohexane, cyclohexane, methylcyclohexane, ethylcyclohexane, isooctane, normal decane, and normal heptane. Examples of the halogen-based solvent include dichloromethane, chloroform, and trichloroethylene. Examples of the ether solvents include diethyl ether, tetrahydrofuran, 1,4-dioxane, 1,3-dioxolane, diisopropyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether acetate, propylene glycol monomethyl ether, 3-methoxy-3-methyl-1-butanol, ethylene glycol monotertiary butyl ether, propylene glycol monomethyl ether propionate, 3-methoxybutanol, diethylene glycol dimethyl ether, anisole, and 4-methylanisole. Examples of the nitrogen-containing solvent include acetonitrile, N,N-dimethylformamide, and N,N-dimethylacetamide. Among these, from the viewpoints of ease of handling and solubility of the imide oligomer, at least one solvent selected from the group consisting of ketone solvents having a boiling point of 60° C. or more and less than 200° C., ester solvents having a boiling point of 60° C. or more and less than 200° C., and ether solvents having a boiling point of 60° C. or more and less than 200° C. is preferred. Examples of such solvents include methyl ethyl ketone, methyl isobutyl ketone, ethyl acetate, isobutyl acetate, 1,4-dioxane, 1,3-dioxolane, tetrahydrofuran, cyclohexanone, methylcyclohexanone, diethylene glycol dimethyl ether, and anisole. The "boiling point" mentioned above means a value measured under a condition of 101 kPa, or a value converted to 101 kPa using a boiling point conversion chart or the like.

[0077] The preferred lower limit of the content of the solvent in 100 parts by weight of the curable resin composition containing the solvent is 20 parts by weight, and the preferred upper limit is 90 parts by weight. When the content of the solvent is within this range, the resulting curable resin composition has better coatability, etc. The more preferred lower limit of the content of the solvent is 30 parts by weight, and the more preferred upper limit is 80 parts by weight.

[0078] The curable resin composition of the present invention may contain a reactive diluent. From the viewpoint of adhesive reliability, the reactive diluent is preferably one having two or more reactive functional groups in one molecule. The curable resin composition of the present invention may further contain additives such as a coupling agent, a dispersant, a storage stabilizer, a bleeding inhibitor, a fluxing agent, and a leveling agent.

[0079] Examples of a method for producing the curable resin composition include a method of using a mixer to mix a curable resin, a curing agent, an inorganic filler, a curing accelerator, etc. Examples of the mixer include a homodisper, a universal mixer, a Banbury mixer, and a kneader.

[0080] The curable resin composition can be applied to a substrate film and dried to obtain a film of the curable resin composition of the present invention before curing.

[0081] The curable resin composition of the present invention can be used in a wide range of applications, but is particularly suitable for electronic material applications requiring high reliability. For example, it can be used as a die attach adhesive in aviation and automotive electrical control units (ECUs) and power device applications using SiC or GaN. It can also be used, for example, as an adhesive for power overlay packages, a sealant, an adhesive for flexible printed circuit boards or coverlay films, copper-clad laminates, semiconductor bonding adhesives, interlayer insulating films, prepregs, LED sealants, and adhesives for structural materials. In particular, it is suitable for bonding flexible printed circuit boards or coverlay films.

[0082] A cured product of the curable resin composition of the present invention also constitutes the present invention. An adhesive made using the curable resin composition of the present invention also constitutes one aspect of the present invention. An adhesive film can be obtained by applying the adhesive of the present invention to a film and then drying it, for example. An adhesive film made using the adhesive of the present invention also constitutes one aspect of the present invention. [Effects of the Invention]

[0083] According to the present invention, it is possible to provide a curable resin composition that has excellent handleability before curing and excellent reliability after curing. Furthermore, according to the present invention, it is possible to provide a cured product of the curable resin composition, and an adhesive and an adhesive film made using the curable resin composition. DETAILED DESCRIPTION OF THE INVENTION

[0084] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0085] (Synthesis Example 1 (Preparation of Imide Oligomer Composition A)) 124 parts by weight of 4,4'-oxydiphthalic anhydride ("ODPA" manufactured by Manac Corporation) was dissolved in 300 parts by weight of N-methylpyrrolidone ("NMP" manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). A solution prepared by diluting 14.2 parts by weight of 1,3-bis(aminomethyl)cyclohexane (manufactured by Tokyo Chemical Industry Co., Ltd.) with 100 parts by weight of N-methylpyrrolidone was added to the resulting solution, and the mixture was stirred at 25°C for 2 hours to allow the reaction to proceed, yielding an amic acid oligomer solution. After removing the N-methylpyrrolidone from the resulting amic acid oligomer solution under reduced pressure, the mixture was heated at 300°C for 2 hours to yield imide oligomer composition A (imidization rate 95%). In addition, 1 H-NMR, GPC, and FT-IR analyses confirmed that imide oligomer composition A contained an imide oligomer having a structure represented by the above formula (4-1) or (4-3) (A is a 4,4'-oxydiphthalic anhydride residue, and B is a 1,3-bis(aminomethyl)cyclohexane residue (having 8 carbon atoms)). The number average molecular weight of imide oligomer composition A was 650.

[0086] (Synthesis Example 2 (Preparation of Imide Oligomer Composition B)) Imide oligomer composition B (imidization rate 93%) was obtained in the same manner as in Synthesis Example 1, except that 11.6 parts by weight of 1,6-diaminohexane (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 14.2 parts by weight of 1,3-bis(aminomethyl)cyclohexane. In addition, 1 H-NMR, GPC, and FT-IR analyses confirmed that imide oligomer composition B contained an imide oligomer having a structure represented by formula (4-1) or (4-3) above (A is a 4,4'-oxydiphthalic anhydride residue, and B is a 1,6-diaminohexane residue (having 6 carbon atoms)). The number-average molecular weight of imide oligomer composition B was 530.

[0087] (Synthesis Example 3 (Preparation of Imide Oligomer Composition C)) Imide oligomer composition C (imidization rate 94%) was obtained in the same manner as in Synthesis Example 1, except that 14.8 parts by weight of 1,2-bis(2-aminoethoxy)ethane (manufactured by Tokyo Chemical Industry Co., Ltd.) was used instead of 14.2 parts by weight of 1,3-bis(aminomethyl)cyclohexane. In addition, 1 H-NMR, GPC, and FT-IR analyses confirmed that imide oligomer composition C contained an imide oligomer having a structure represented by formula (4-1) or (4-3) above (A is a 4,4'-oxydiphthalic anhydride residue, and B is a 1,2-bis(2-aminoethoxy)ethane residue (carbon number: 6)). The number average molecular weight of imide oligomer composition C was 670.

[0088] (Synthesis Example 4 (Preparation of Imide Oligomer Composition D)) Imide oligomer composition D (imidization rate 94%) was obtained in the same manner as in Synthesis Example 1, except that 29.2 parts by weight of 1,3-bis(4-aminophenoxy)benzene (manufactured by Seika Corporation, "TPE-R") was used instead of 14.2 parts by weight of 1,3-bis(aminomethyl)cyclohexane. In addition, 1 H-NMR, GPC, and FT-IR analyses confirmed that imide oligomer composition D contained an imide oligomer having a structure represented by formula (4-1) or (4-3) above (A is a 4,4'-oxydiphthalic anhydride residue, and B is a 1,3-bis(4-aminophenoxy)benzene residue). The number-average molecular weight of imide oligomer composition D was 810.

[0089] (Synthesis Example 5 (Preparation of Imide Oligomer Composition E)) Imide oligomer composition E (imidization rate 96%) was obtained in the same manner as in Synthesis Example 1, except that 56.0 parts by weight of Priamine 1074 (manufactured by Croda), a dimer diamine, was used instead of 14.2 parts by weight of 1,3-bis(aminomethyl)cyclohexane. In addition, 1H-NMR, GPC, and FT-IR analyses confirmed that imide oligomer composition E contained an imide oligomer having a structure represented by the above formula (4-1) or (4-3) (A is a 4,4'-oxydiphthalic anhydride residue, and B is a dimer diamine residue (having 34 carbon atoms)). The number-average molecular weight of imide oligomer composition E was 1,100.

[0090] (Example 1 6、8、 9 See Example 7 , Comparative Examples 1 to 5) Each material was mixed and stirred according to the compounding ratios shown in Tables 1 and 2 to prepare each curable resin composition. Each of the obtained curable resin compositions was applied onto a substrate PET film and dried to form a film of Examples 1 to 3 on the substrate PET film. 6、8、 9 See Example 7 Films (thickness: 150 μm) were prepared from the curable resin compositions of Comparative Examples 1 to 5. The resulting film was punched into strips measuring 100 mm long x 10 mm wide to prepare test specimens. The resulting test specimens were stretched at 25°C using a tensile tester (A&D Corporation, "Tensilon Universal Tester RTI-1310") at a rate of 200 mm / min, and the elongation at break was measured as the elongation at the break point. The results are shown in Tables 1 and 2. The resulting film was heated at 190°C for 1 hour to produce a cured product. The tensile storage modulus of the resulting cured product was measured at 150°C using a dynamic viscoelasticity measuring device (IT Measurement Co., Ltd., "DVA-200") at 10 Hz and a strain of 0.1%. The results are shown in Tables 1 and 2.

[0091] <Evaluation> Example Reference example and 、 The curable resin compositions obtained in the comparative examples were evaluated as follows, and the results are shown in Tables 1 and 2.

[0092] (Handling before hardening) Example Reference example and 、A 5 mm diameter winding test was conducted in which the film-formed product of each curable resin composition obtained in the comparative examples was wrapped around a 5 mm diameter cylinder at 25°C to check for cracks or chips in the curable resin composition. In addition, a 180-degree bending test was conducted in which the obtained film-formed product was bent 180 degrees to check for cracks or chips in the curable resin composition. Handling was evaluated as follows: "○" indicates that there were no cracks or chips in both the 5 mm diameter winding test and the 180-degree bending test; "△" indicates that there were no cracks or chips in the 5 mm diameter winding test but there were cracks or chips in the 180-degree bending test; and "×" indicates that there were cracks or chips in both tests.

[0093] (Reliability) Example Reference example and 、 Each curable resin composition obtained in the comparative examples was applied to a polyimide substrate measuring 10 mm in length and 10 mm in width, and a silicon chip measuring 50 μm in length, 3 mm in width, and 3 mm in thickness was then layered on top. The curable resin composition was then cured by heating at 190°C for 1 hour to obtain a test piece. The obtained test piece was subjected to a thermal cycling test in which 1000 cycles of -55°C / 16 minutes and 150°C / 16 minutes were performed. The adhesive surface between the silicon chip and the cured product of the curable resin composition was then visually or microscopically observed from the polyimide side to confirm the presence or absence of cracks. The reliability of the cured product was evaluated by assigning "○" to cases where no cracks were observed and "×" to cases where cracks were observed.

[0094] [Table 1]

[0095] [Table 2] [Industrial Applicability]

[0096] According to the present invention, it is possible to provide a curable resin composition that has excellent handleability before curing and excellent reliability after curing. Furthermore, according to the present invention, it is possible to provide a cured product of the curable resin composition, and an adhesive and an adhesive film made using the curable resin composition.

Claims

1. Contains a curable resin, a curing agent, and an inorganic filler, the curable resin includes an epoxy resin, the curing agent comprises an imide oligomer; The imide oligomer has a structure represented by the following formula (1-1) or the following formula (1-2): The imide oligomer has a number average molecular weight of 5,000 or less, the content of the inorganic filler is 20 parts by weight or more and 50 parts by weight or less based on 100 parts by weight of the total of the curable resin, the curing agent, and the inorganic filler; The breaking elongation of a 150 μm thick film before curing is 72% or more, and the tensile storage modulus of the cured product at 150° C. is 2.5 GPa or more. A curable resin composition characterized by: 【Chemistry 1】 In formula (1-1) and formula (1-2), A is an acid dianhydride residue, B is an aliphatic diamine residue, and in formula (1-2), Ar is an optionally substituted divalent aromatic group.

2. The curable resin composition according to claim 1, wherein B in the formula (1-1) and the formula (1-2) is an aliphatic diamine residue having 4 to 30 carbon atoms.

3. The curable resin composition according to claim 1, wherein A in the formula (1-1) and the formula (1-2) is an aromatic tetracarboxylic dianhydride residue which may be substituted.

4. 4. The curable resin composition according to claim 1, wherein the content of the curing agent is 20 parts by weight or more and 40 parts by weight or less per 100 parts by weight of the total of the curable resin, the curing agent, and the inorganic filler.

5. 5. The curable resin composition according to claim 1, wherein the inorganic filler comprises at least one selected from the group consisting of silica and barium sulfate.

6. 6. The curable resin composition according to claim 1, wherein the inorganic filler has an average particle size of 0.1 μm or more and 1.0 μm or less.

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

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

9. An adhesive film obtained by using the adhesive according to claim 8.

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