Curable resin composition and cured product thereof

Abstract

The present invention provides a curable resin composition from which a cured product that has excellent low-dielectric properties is obtained without inhibition of a curing reaction.　Provided is a curable resin composition comprising a compound which is represented by formula (1) and a compound which has a phenolic hydroxyl group, wherein the content of the compound which has a phenolic hydroxyl group is 0.0001-0.13 parts by mass relative to 100 parts by mass of the compound which is represented by formula (1). (In formula (1), X is a C1-25 hydrocarbon, and each R independently represents a hydrogen atom or a C1-5 hydrocarbon group. Each m is independently an integer of 1-3. n is the average number of repeating units, and is a number of 1-20.)

Description

Curable resin composition and cured product thereof

[0001] The present invention relates to a curable resin composition and a cured product thereof, which are suitable for use in electrical and electronic components such as semiconductor encapsulants, printed wiring boards, and build-up laminates, lightweight, high-strength materials such as carbon fiber reinforced plastics and glass fiber reinforced plastics, and 3D printing applications.

[0002] In recent years, the required characteristics of laminates for mounting electrical and electronic components have become more widespread and sophisticated due to the expansion of their application fields. Conventional semiconductor chips were mainly mounted on metal lead frames, but semiconductor chips with high processing power, such as central processing units (hereinafter referred to as CPUs), are increasingly being mounted on laminates made of polymer materials.

[0003] The fifth-generation communication system (5G), currently undergoing accelerated development, is expected to further increase capacity and speed. 5G will use increasingly higher frequencies. Reducing transmission loss is crucial to achieving high-speed communication using high frequencies, necessitating even lower dielectric properties in circuit board materials. Transmission loss on printed circuit boards is due to conductor loss and dielectric loss. As noted in Non-Patent Document 1, conductor loss is proportional to the square root of the dielectric constant and the dielectric loss tangent of the dielectric. Therefore, improving the dielectric loss tangent, which contributes more than the dielectric constant, is an effective way to reduce transmission loss. Low-dielectric materials include thermoplastic materials such as PTFE (polytetrafluoroethylene) and LCP (liquid crystal polymer), but they have poor moldability compared to thermosetting resins. Given this, the development of thermosetting resins and curable resin compositions with excellent low-dielectric properties is desired.

[0004] In light of this background, thermosetting resin compositions exhibiting low dielectric loss tangents have been investigated. For example, Patent Document 1 discloses a curable resin composition containing bisvinylphenylethane (BVPE) and thermosetting polyphenylene ether (Patent Document 1). This curable resin composition uses a polymerization inhibitor, 2,5-bis(1,1-dimethylbutyl)hydroquinone, to improve the storage stability of the resin composition.

[0005] Generally, when a polymerization inhibitor having a polar group (a substituent containing a heteroatom) in its structure is used, the storage stability improves as the amount added increases, but on the other hand, the dielectric properties deteriorate, resulting in a trade-off. Furthermore, the optimal polymerization inhibitor changes depending on the target compound for which storage stability needs to be improved, making the selection of the optimal polymerization inhibitor both difficult and an important issue.

[0006] Patent Document 2 discloses a composition containing a maleimide compound, an epoxy resin, and a phenolic resin, and aims to improve storage stability by melt-mixing these components and solidifying them. This approach is preferable from the perspective of long-term transportation, such as by sea, and is preferred because it does not deteriorate even in the on-board environment, which can reach temperatures of 60°C or higher in the summer. However, since specific components are pre-mixed, they must be re-dissolved in an organic solvent after transportation in order to be mixed with other materials, which also limits the range of components available for the composition. Furthermore, the composition contains compounds, such as epoxy resins, that generate polar groups such as hydroxyl groups upon curing, which is undesirable from the perspective of improving dielectric properties.

[0007] "Signal Loss Factors in High-Speed ​​Signal Transmission on Printed Circuit Boards," 29th Spring Conference of the Japan Institute of Electronics Packaging, Session ID: 16P1-17, 2015

[0008] JP 2008-115280 A JP 2017-101152 A

[0009] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a curable resin composition that does not inhibit the curing reaction and that gives a cured product with excellent low dielectric properties.

[0010] That is, the present invention relates to the following [1] to [5]. In the present invention, "(Numerical value 1) to (Numerical value 2)" indicates that the upper and lower limits are included. [1] A curable resin composition containing a compound represented by the following formula (1) and a compound having a phenolic hydroxyl group, wherein the content of the compound having a phenolic hydroxyl group is 0.0001 parts by mass or more and 0.13 parts by mass or less per 100 parts by mass of the compound represented by the following formula (1):

[0011]

[0012] (In the above formula (1), X is a hydrocarbon having 1 to 25 carbon atoms, and a plurality of R each independently represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms. Each m is independently an integer of 1 to 3. n is the average number of repetitions and is a number of 1 to 20.) [2] The curable resin composition according to the above item [1], wherein X in the compound represented by formula (1) is any of structures represented by the following formulas (A) to (H):

[0013]

[0014] (In the above formulas (A) to (H), each of the multiple R's independently represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms. Each of the multiple a's independently represents an integer of 1 to 4. Each of the multiple b's independently represents an integer of 1 to 3.) [3] The curable resin composition according to the above item [1] or [2], wherein the compound having a phenolic hydroxyl group is at least one selected from the group consisting of compounds represented by the following formula (2-1) and compounds represented by the following formula (2-2):

[0015]

[0016] (In the above formulas (2-1) and (2-2), there are multiple R １ , R ２ each independently represent a hydrocarbon group having 1 to 10 carbon atoms. p is an integer of 1 to 5. q is an integer of 1 to 4.) [4] The curable resin composition according to any one of the preceding items [1] to [3], further containing one or more of a curing accelerator, a polymerization initiator, an epoxy resin, an active ester compound, a phenolic resin, a polyphenylene ether compound, an amine resin, a compound having an ethylenically unsaturated bond, an isocyanate resin, a polyamide resin, a maleimide compound, a cyanate ester resin, a polyimide resin, polybutadiene and modified products thereof, polystyrene and modified products thereof, polyethylene and modified products thereof, and a benzoxazine compound. [5] A cured product obtained by curing the curable resin composition according to any one of the preceding items [1] to [4].

[0017] According to the present invention, it is possible to provide a curable resin composition that does not inhibit the curing reaction and that can give a cured product with excellent low dielectric properties.

[0018] Hereinafter, an embodiment of the present invention (hereinafter also referred to as "the present embodiment") will be described in further detail.

[0019] The curable resin composition of the present embodiment contains a compound represented by the following formula (1) and a compound having a phenolic hydroxyl group.

[0020]

[0021] In the above formula (1), X represents a hydrocarbon having 1 to 25 carbon atoms, preferably containing a methylene chain, an alicyclic structure, or an aromatic ring, more preferably containing a methylene chain or an aromatic ring, and even more preferably containing at least one aromatic ring. The inclusion of an aromatic ring suppresses molecular vibration, improving dielectric properties and also contributing to improved heat resistance. Multiple Rs each independently represent a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms. Hydrocarbons having 5 or fewer carbon atoms are less likely to undergo molecular vibration when exposed to high frequency waves, resulting in particularly excellent electrical properties. Furthermore, solvent solubility can be imparted without significantly impairing heat resistance. Each m is independently an integer from 1 to 3, more preferably 1 to 2. n represents the average number of repeating units and is a number from 1 to 20, more preferably 1.1 to 20, particularly preferably 1.1 to 10, and most preferably 1.1 to 5. The value of n can be calculated from the number average molecular weight (Mn) value determined by gel permeation chromatography (GPC) measurement of the compound represented by formula (1). The number average molecular weight is preferably 200 or more but less than 5000, more preferably 300 or more but less than 3000, and particularly preferably 400 or more but less than 2000. When the weight average molecular weight is less than 5000, purification by washing with water becomes easy, and when it is 200 or more, the target compound does not volatilize in the solvent distillation step.

[0022] In the above formula (1), it is particularly preferable that X is any of the structures represented by the following formulas (A) to (H).

[0023]

[0024] In the above formulas (A) to (H), each of the multiple R's independently represents a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms, preferably a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms. Hydrocarbons having 5 or fewer carbon atoms are less likely to undergo molecular vibration when exposed to high frequency waves, and therefore have particularly excellent electrical properties. Furthermore, solvent solubility can be imparted without significantly impairing heat resistance. Each of the multiple a's independently represents an integer of 1 to 4, preferably an integer of 1 to 3, and more preferably an integer of 1 or 2. Each of the multiple b's independently represents an integer of 1 to 3, and more preferably an integer of 1 or 2.

[0025] The curable resin composition of this embodiment further contains a compound having a phenolic hydroxyl group. The amount of the compound having a phenolic hydroxyl group added is preferably 0.0001 parts by mass or more and 0.13 parts by mass or less, more preferably 0.001 parts by mass or more and 0.1 parts by mass or less, and even more preferably 0.003 parts by mass or more and 0.075 parts by mass or less, relative to 100 parts by mass of the compound represented by formula (1). 0.005 parts by mass or more and 0.05 parts by mass or less is particularly preferred. If the amount is less than 0.0001 parts by mass, a sufficient polymerization inhibitory effect may not be obtained, and if the amount is more than 0.13 parts by mass, significant curing defects may occur.

[0026] The compound having a phenolic hydroxyl group is preferably a compound represented by the following formula (2-1) or (2-2).

[0027]

[0028] In the above formula (2-1), R １ represents a hydrocarbon group having 1 to 10 carbon atoms, preferably a hydrocarbon group having 1 to 7 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms. p represents an integer of 1 to 5, preferably an integer of 2 to 4, and particularly preferably 3. In the above formula (2-2), R ２represents a hydrocarbon group having 1 to 10 carbon atoms, preferably a hydrocarbon group having 1 to 7 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms. q is an integer of 1 to 4, preferably an integer of 1 to 3, and more preferably an integer of 1 or 2. The hydrocarbon group donates hydrogen to the phenoxy radical to regenerate a phenolic hydroxyl group, thereby enhancing the polymerization-inhibiting effect.

[0029] The compound represented by the above formula (2-1) or (2-2) is particularly preferably represented by any of the structures of the following formulas (2-a) to (2-b). The compound represented by the following formula (2-a) has the effect of reducing polarity by introducing a bulky alkyl group near the hydroxyl group. Furthermore, due to the high molecular symmetry, deterioration of dielectric properties due to addition can be minimized. The compound represented by the following formula (2-b) can minimize highly polar hydroxyl groups remaining in the system by adopting a quinone structure after capturing radicals. In the following formula (2-b), a phenolic hydroxyl group introduced at the para-position relative to one hydroxyl group increases the electron density of the compound represented by the following formula (2-b), thereby having the effect of improving radical scavenging performance.

[0030]

[0031] In addition to the compound represented by formula (1) and the compound represented by formula (2), various materials may be added to the curable resin composition of the present embodiment to improve its performance.

[0032] [Polymerization inhibitor] The curable resin composition of the present embodiment may contain other polymerization inhibitors in addition to the compounds represented by the above formulas (2-1) and (2-2). However, when a polymerization inhibitor is used, the amount added is limited to a range that does not significantly affect the dielectric properties and curing properties of the curable resin composition of the present embodiment.

[0033] Examples of the polymerization inhibitor include phenol-based, sulfur-based, phosphorus-based, hindered amine-based, nitroso-based, and nitroxyl radical-based inhibitors.

[0034] Examples of the phenolic polymerization inhibitor include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-p-ethylphenol, stearyl-β-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, isooctyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,4-bis-(n-octylthio)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5-triazine, 2,4-bis[(octylthio)methyl]-o ...butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyanisole, butylated hydroxyani Monophenols such as resol, 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], 3,5-di-t-butyl-4-hydroxybenzylphosphonate-diethyl ester, 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, bis(3,5-di-t-butyl bisphenols such as calcium ethyl-4-hydroxybenzylsulfonate, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane, 1,3,5-trimethyl-2,4,6-tris(3,5-di-t-butyl-4-hydroxybenzyl)benzene, tetrakis-[methylene-3-(3',5'-di-t-butyl-4'-hydroxyphenyl)propionate]methane, bis[3,3'-bis-(4'-hydroxy-3'-t-butylphenyl)butyric acid]glycol ester, tris-(3,Examples of the polymerizable phenols include, but are not limited to, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-isocyanurate, 1,3,5-tris(3',5'-di-t-butyl-4'-hydroxybenzyl)-s-triazine-2,4,6-(1H,3H,5H)trione, and tocopherol.

[0035] Examples of the sulfur-based polymerization inhibitor include, but are not limited to, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate.

[0036] Examples of the phosphorus-based polymerization inhibitor include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, diisodecyl pentaerythritol phosphite, tris(2,4-di-t-butylphenyl) phosphite, cyclic neopentane tetrayl bis(octadecyl) phosphite, cyclic neopentane tetrayl bis(2,4-di-t-butylphenyl) phosphite, cyclic neopentane tetrayl bis(2,4-di-t-butyl-4-methylphenyl) phosphite, bis[2- phosphites such as t-butyl-6-methyl-4-{2-(octadecyloxycarbonyl)ethyl}phenyl]hydrogen phosphite, and oxaphosphaphenanthrene oxides such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, but are not limited to these.

[0037] Examples of the hindered amine polymerization inhibitor include ADK STAB LA-40MP, ADK STAB LA-40Si, ADK STAB LA-402AF, ADK STAB LA-87, ADK STAB LA-82, ADK STAB LA-81, ADK STAB LA-77Y, ADK STAB LA-77G, ADK STAB LA-72, ADK STAB LA-68, ADK STAB LA-63P, ADK STAB LA-57, ADK STAB LA-52, Chimassorb 2020FDL, Chimassorb 944FDL, Chimassorb 944LD, Tinuvin 622SF, Tinuvin PA144, Tinuvin 765, Tinuvin 770DF, Tinuvin XT55FB, Tinuvin 111FDL, Tinuvin 783FDL, Tinuvin 791FB and the like, but are not limited thereto.

[0038] Examples of the nitroso-based polymerization inhibitor include, but are not limited to, p-nitrosophenol, N-nitrosodiphenylamine, and the ammonium salt of N-nitrosophenylhydroxyamine (cupferron). Of these, the ammonium salt of N-nitrosophenylhydroxyamine (cupferron) is preferred.

[0039] Examples of the nitroxyl radical polymerization inhibitor include di-tert-butyl nitroxide, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-acetoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl, but are not limited to these.

[0040] The compound represented by the formula (1) can be cured by itself by heating or the like, but performance can also be improved by adding various materials to form a curable resin composition.

[0041] [Curing Accelerator] The curability of the curable resin composition of the present embodiment can be improved by adding a curing accelerator. As the curing accelerator, an anionic curing accelerator that accelerates the curing reaction by generating anions upon irradiation with ultraviolet light or visible light or heating, or a cationic curing accelerator that accelerates the curing reaction by generating cations upon irradiation with ultraviolet light or visible light or heating, is preferred.

[0042] Examples of anionic curing accelerators include imidazoles such as 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4-methylimidazole; trialkylamines such as triethylamine and tributylamine; 4-dimethylaminopyridine, benzyldimethylamine, 2,4,6-tris(dimethylaminomethyl)phenol, and 1,8-diazabicyclo(5,4,0)-undecene, with 4-dimethylaminopyridine and 1,8-diazabicyclo(5,4,0)-undecene being preferred. Other examples include phosphines such as triphenylphosphine; and quaternary ammonium salts such as tetrabutylammonium salt, triisopropylmethylammonium salt, trimethyldecanylammonium salt, cetyltrimethylammonium salt, and hexadecyltrimethylammonium hydroxide, but are not limited thereto. These may be used alone or in combination.

[0043] Examples of cationic curing accelerators include quaternary phosphonium salts such as triphenylbenzylphosphonium salt, triphenylethylphosphonium salt, and tetrabutylphosphonium salt (the counter ion of the quaternary salt may be a halogen, an organic acid ion, a hydroxide ion, or the like, and is not particularly specified, but an organic acid ion or a hydroxide ion is particularly preferred), and transition metal compounds (transition metal salts) such as tin octylate, zinc carboxylate (zinc 2-ethylhexanoate, zinc stearate, zinc behenate, zinc myristate), and zinc phosphate ester (zinc octylphosphate, zinc stearylphosphate), but are not limited thereto. These may be used alone or in combination.

[0044] The curing accelerator is used in an amount of 0.01 to 5.0 parts by mass based on 100 parts by mass of the curable resin composition, as needed.

[0045] [Inorganic Filler] The curable resin composition of the present embodiment may contain an inorganic filler. Examples of inorganic fillers include, but are not limited to, powders such as fused silica, crystalline silica, porous silica, alumina, zircon, calcium silicate, calcium carbonate, quartz powder, silicon carbide, silicon nitride, boron nitride, zirconia, aluminum nitride, graphite, forsterite, steatite, spinel, mullite, titania, talc, clay, iron oxide, asbestos, and glass powder, as well as inorganic fillers obtained by shaping these into a spherical or crushed form. These fillers may be used alone or in combination.

[0046] When a curable resin composition for semiconductor encapsulation is obtained, the amount of inorganic filler used is preferably 80 to 92 parts by mass, and more preferably 83 to 90 parts by mass, per 100 parts by mass of the curable resin composition. When a curable resin composition for interlayer insulating layer formation, or a substrate material such as a copper-clad laminate, prepreg, or RCC is obtained, the amount of inorganic filler used is preferably 5 to 80 parts by mass, and more preferably 10 to 60 parts by mass, per 100 parts by mass of the curable resin composition.

[0047] [Polymerization Initiator] The curability of the curable resin composition of this embodiment can be improved by adding a polymerization initiator. The polymerization initiator is a compound capable of polymerizing an olefin functional group such as an ethylenically unsaturated bond, and examples thereof include an olefin metathesis polymerization initiator, an anionic polymerization initiator, a cationic polymerization initiator, and a radical polymerization initiator. Among these, it is preferable to use a radical polymerization initiator that has curability and appropriate stability. The radical polymerization initiator is a compound that generates radicals upon irradiation with ultraviolet light or visible light or heating, thereby initiating a chain polymerization reaction. Usable radical polymerization initiators include organic peroxides, azo compounds, and benzopinacols. Organic peroxides are preferred because they are effective in controlling the curing temperature, suppress outgassing, and minimize the impact of decomposition products on electrical properties.

[0048] Examples of the organic peroxides include ketone peroxides such as methyl ethyl ketone peroxide and acetylacetone peroxide, diacyl peroxides such as benzoyl peroxide, dialkyl peroxides such as dicumyl peroxide and 1,3-bis-(t-butylperoxyisopropyl)-benzene, peroxyketals such as t-butyl peroxybenzoate and 1,1-di-t-butylperoxycyclohexane, α-cumylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhexanoate, t-butylperoxymethyl ... Examples of the peroxycarbonate include, but are not limited to, alkyl peresters such as di-2-ethylhexyl peroxydicarbonate, t-amylperoxy-3,5,5-trimethylhexanoate, t-butylperoxy-3,5,5-trimethylhexanoate, and t-amylperoxybenzoate, peroxycarbonates such as di-2-ethylhexyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, t-butylperoxyisopropyl carbonate, and 1,6-bis(t-butylperoxycarbonyloxy)hexane, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctoate, and lauroyl peroxide. These peroxycarbonates may be used alone or in combination. Among the above organic peroxides, ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, peroxycarbonates, etc. are preferred, with dialkyl peroxides being more preferred.

[0049] Examples of the azo compounds include, but are not limited to, azobisisobutyronitrile, 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2,4-dimethylvaleronitrile), etc. These compounds may be used alone or in combination.

[0050] The amount of polymerization initiator added is preferably 0.01 to 5 parts by mass, and particularly preferably 0.01 to 3 parts by mass, relative to 100 parts by mass of the curable resin composition. If the amount of polymerization initiator used is less than 0.01 part by mass, there is a risk that the molecular weight will not be sufficiently elongated during the polymerization reaction, and if it is more than 5 parts by mass, there is a risk that the dielectric properties such as the dielectric constant and the dielectric loss tangent will be impaired.

[0051] [Flame Retardant] The curable resin composition of the present embodiment may contain a flame retardant. Examples of the flame retardant include halogen-based flame retardants, inorganic flame retardants (antimony compounds, metal hydroxides, nitrogen compounds, boron compounds, etc.), and phosphorus-based flame retardants. From the viewpoint of achieving halogen-free flame retardancy, phosphorus-based flame retardants are preferred.

[0052] The phosphorus-based flame retardant may be a reactive type or an additive type. Specific examples include phosphate esters such as trimethyl phosphate, triethyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresyl diphenyl phosphate, cresyl-2,6-dixylenyl phosphate, 1,3-phenylenebis(dixylenyl phosphate), 1,4-phenylenebis(dixylenyl phosphate), and 4,4'-biphenyl(dixylenyl phosphate); phosphanes such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide and 10(2,5-dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide; phosphorus-containing epoxy compounds obtained by reacting an epoxy resin with the active hydrogen of the above-mentioned phosphanes; and red phosphorus. These may be used alone or in combination. Of the above-listed substances, phosphate esters, phosphanes, and phosphorus-containing epoxy compounds are preferred, with 1,3-phenylenebis(dixylenyl phosphate), 1,4-phenylenebis(dixylenyl phosphate), 4,4'-biphenyl(dixylenyl phosphate), and phosphorus-containing epoxy compounds being particularly preferred.

[0053] The content of the flame retardant is preferably in the range of 0.1 to 0.6 parts by mass per 100 parts by mass of the curable resin composition. If the content is less than 0.1 part by mass, the flame retardancy may be insufficient, and if the content is more than 0.6 part by mass, the moisture absorption and dielectric properties of the cured product may be adversely affected.

[0054] [Light Stabilizer] The curable resin composition of the present embodiment may contain a light stabilizer. As the light stabilizer, a hindered amine light stabilizer, particularly HALS, etc., is preferred. Examples of HALS include reaction products of dibutylamine, 1,3,5-triazine, N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidyl)butylamine, reaction products of dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, and poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3,5-triazine-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidyl) Examples of suitable hydroxybenzyl compounds include, but are not limited to, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, and bis(1,2,2,6,6-pentamethyl-4-piperidyl) 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate. These compounds may be used alone or in combination.

[0055] The content of the light stabilizer is preferably in the range of 0.001 to 0.1 parts by mass relative to 100 parts by mass of the curable resin composition. If the content is less than 0.001 part by mass, the light stabilizing effect may be insufficient, and if the content is more than 0.1 part by mass, the moisture absorption and dielectric properties of the cured product may be adversely affected.

[0056] [Binder Resin] The curable resin composition of this embodiment may use a binder resin. Examples of binder resins include, but are not limited to, butyral-based resins, acetal-based resins, acrylic-based resins, epoxy-nylon-based resins, NBR-phenol-based resins, epoxy-NBR-based resins, and silicone-based resins. These may be used alone or in combination.

[0057] The blending amount of the binder resin is preferably within a range that does not impair the flame retardancy and heat resistance of the cured product, and is preferably 0.05 to 50 parts by mass, and more preferably 0.05 to 20 parts by mass, per 100 parts by mass of the curable resin composition, as needed.

[0058] [Additives] The curable resin composition of the present embodiment may contain additives, such as modified acrylonitrile copolymers, polyethylene, fluororesins, silicone gels, silicone oils, surface treatment agents for fillers such as silane coupling agents, release agents, and colorants such as carbon black, phthalocyanine blue, and phthalocyanine green.

[0059] The amount of the additive to be added is preferably 1,000 parts by mass or less, more preferably 700 parts by mass or less, per 100 parts by mass of the curable resin composition.

[0060] The curable resin composition of this embodiment may further contain epoxy resins, active ester compounds, phenolic resins, polyphenylene ether compounds, amine resins, compounds having an ethylenically unsaturated bond, isocyanate resins, polyamide resins, maleimide compounds, cyanate ester resins, polyimide resins, polybutadiene and modified products thereof, polystyrene and modified products thereof, polyethylene and modified products thereof, etc., and these may be used alone or in combination. Among these compounds, polyphenylene ether compounds, compounds having an ethylenically unsaturated bond, cyanate ester resins, polybutadiene and modified products thereof, and polystyrene and modified products thereof are preferred in terms of the balance of heat resistance, adhesion, and dielectric properties. By containing these compounds, the brittleness of the cured product and adhesion to metals can be improved, and package cracking can be suppressed during reliability tests such as solder reflow and thermal cycling.

[0061] Unless otherwise specified, the amount of the above compound used is preferably 10 times by mass or less, more preferably 5 times by mass or less, and particularly preferably 3 times by mass or less, relative to the compound represented by formula (1). The preferred lower limit is 0.1 times by mass or more, more preferably 0.25 times by mass or more, and even more preferably 0.5 times by mass or more. By keeping the amount within the above range, the effects of each compound added can be enhanced while taking advantage of the low dielectric properties of the compound of this embodiment. The following examples of these components can be used.

[0062] [Epoxy Resin] Preferred examples of epoxy resins are shown below, but are not limited to these. The epoxy resin may be liquid or solid, and may be used alone or in combination.

[0063] Examples of liquid epoxy resins include bisphenol A type epoxy resins, bisphenol F type epoxy resins, bisphenol AF type epoxy resins, naphthalene type epoxy resins, glycidyl ester type epoxy resins, glycidyl amine type epoxy resins, phenol novolac type epoxy resins, alicyclic epoxy resins having an ester skeleton, cyclohexane type epoxy resins, cyclohexane dimethanol type epoxy resins, and epoxy resins having a butadiene structure. Specific examples include "RE310S" and "RE410S" (all manufactured by Nippon Kayaku Co., Ltd., bisphenol A type epoxy resins), "RE303S", "RE304S", "RE403S", and "RE404S" (all manufactured by Nippon Kayaku Co., Ltd., bisphenol F type epoxy resins), "HP4032", "HP4032D", and "HP4032SS" (all manufactured by DIC Corporation, naphthalene type epoxy resins), "828US", "jER828EL", "825", and "828EL" (all manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resins), "jE807", and "1750" (all manufactured by Mitsubishi Chemical Corporation, bisphenol F type epoxy resins), and "jER152" (manufactured by Mitsubishi Chemical Corporation, phenolic novolac type epoxy resin), "630", "630LSD" (all manufactured by Mitsubishi Chemical Corporation, glycidylamine type epoxy resin), "ZX1059" (manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., a mixture of bisphenol A type epoxy resin and bisphenol F type epoxy resin), "EX-721" (manufactured by Nagase ChemteX Corporation, glycidyl ester type epoxy resin), "Celloxide 2021P" (manufactured by Daicel Corporation, alicyclic epoxy resin having an ester skeleton), "PB-3600" (manufactured by Daicel Corporation, epoxy resin having a butadiene structure), "ZX1658", "ZX1658GS" (all manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., liquid 1,4-glycidylcyclohexane type epoxy resin). These may be used alone or in combination of two or more.

[0064] Preferred examples of solid epoxy resins include bixylenol-type epoxy resins, naphthalene-type epoxy resins, naphthalene-type tetrafunctional epoxy resins, cresol novolac-type epoxy resins, dicyclopentadiene-type epoxy resins, trisphenol-type epoxy resins, naphthol-type epoxy resins, biphenyl-type epoxy resins, naphthylene ether-type epoxy resins, anthracene-type epoxy resins, bisphenol A-type epoxy resins, bisphenol AF-type epoxy resins, and tetraphenylethane-type epoxy resins, and examples of such solid epoxy resins include naphthol-type epoxy resins, bisphenol AF-type epoxy resins, naphthalene-type epoxy resins, and biphenyl-type epoxy resins.Specific examples include "HP4032H" (manufactured by DIC Corporation, naphthalene-type epoxy resin), "HP-4700", and "HP-4710" (all manufactured by DIC Corporation, naphthalene-type tetrafunctional epoxy resin), "N-690" (manufactured by DIC Corporation, cresol novolac-type epoxy resin), "N-695" (manufactured by DIC Corporation, cresol novolac-type epoxy resin), "HP-7200", "HP-7200HH", and "HP-7200H" (all manufactured by DIC Corporation, dicyclopentadiene-type epoxy resin), "EXA-7311", and "EXA-7311-G3 "," "EXA-7311-G4," "EXA-7311-G4S," "HP-6000" (all manufactured by DIC Corporation, naphthylene ether type epoxy resin), "EPPN-502H" (manufactured by Nippon Kayaku Co., Ltd., trisphenol type epoxy resin), "NC-7000L," "NC-7300" (all manufactured by Nippon Kayaku Co., Ltd., naphthol-cresol novolac type epoxy resin), "NC-3000H," "NC-3000," "NC-3000L," "NC-3100" (all manufactured by Nippon Kayaku Co., Ltd., biphenyl aralkyl type epoxy resin), "XD- 1000-2L, XD-1000-L, XD-1000-H, XD-1000-H (all manufactured by Nippon Kayaku Co., Ltd., dicyclopentadiene-type epoxy resin), ESN475V (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., naphthol-type epoxy resin), ESN485 (manufactured by Nippon Steel & Sumikin Chemical Co., Ltd., naphthol novolac-type epoxy resin), YX-4000H, YX-4000, YL6121 (all manufactured by Mitsubishi Chemical Corporation, biphenyl-type epoxy resin), YX-4000HK (manufactured by Mitsubishi Chemical Corporation, bixylenol-type epoxy resin) resin), "YX-8800" (manufactured by Mitsubishi Chemical Corporation, anthracene-type epoxy resin), "PG-100", "CG-500" (manufactured by Osaka Gas Chemicals Co., Ltd., fluorene-based epoxy resin), "YL-7760" (manufactured by Mitsubishi Chemical Corporation, bisphenol AF-type epoxy resin), "YL-7800" (manufactured by Mitsubishi Chemical Corporation, fluorene-type epoxy resin), "jER1010" (manufactured by Mitsubishi Chemical Corporation, solid bisphenol A-type epoxy resin), and "jER1031S" (manufactured by Mitsubishi Chemical Corporation, tetraphenylethane-type epoxy resin). These may be used alone or in combination of two or more.

[0065] [Active Ester Compound] An active ester compound refers to a compound containing at least one ester bond in its structure, and having an aliphatic chain, an aliphatic ring, or an aromatic ring bonded to both sides of the ester bond. Examples of active ester compounds include compounds having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. These active ester compounds are obtained by a condensation reaction between at least one compound selected from a carboxylic acid compound, an acid chloride, and a thiocarboxylic acid compound and at least one compound selected from a hydroxy compound and a thiol compound. In particular, from the viewpoint of improving heat resistance, active ester compounds obtained from a carboxylic acid compound or an acid chloride and a hydroxy compound are preferred, and the hydroxy compound is preferably a phenol compound or a naphthol compound. Active ester compounds may be used alone or in combination of two or more types.

[0066] Examples of the carboxylic acid compound include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

[0067] Examples of the acid chloride include acetyl chloride, acrylic acid chloride, methacrylic acid chloride, malonyl chloride, succinic acid dichloride, diglycolyl chloride, glutaric acid dichloride, suberic acid dichloride, sebacic acid dichloride, adipic acid dichloride, dodecandioyl dichloride, azelaic acid chloride, 2,5-furandicarbonyl dichloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, trimesic acid chloride, bis(4-chlorocarbonylphenyl) ether, 4,4'-diphenyldicarbonyl chloride, and 4,4'-azodibenzoyl dichloride.

[0068] Examples of the phenol compound and naphthol compound include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucinol, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolak, and the phenolic resins described below. Here, the term "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by condensing one molecule of dicyclopentadiene with two molecules of phenol.

[0069] Preferred specific examples of the active ester compound include active ester compounds containing a dicyclopentadiene-type diphenol structure, active ester compounds containing a naphthalene structure, active ester compounds containing an acetylated phenol novolac, active ester compounds containing a benzoylated phenol novolac, the compound described in Example 2 of WO 2020 / 095829, and the compounds disclosed in WO 2020 / 059625. Among these, active ester compounds containing a naphthalene structure and active ester compounds containing a dicyclopentadiene-type diphenol structure are more preferred. The dicyclopentadiene-type diphenol structure refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0070] Commercially available active ester compounds include, for example, "EXB9451," "EXB9460," "EXB9460S," "HPC-8000-65T," "HPC-8000H-65TM," "EXB-8000L-65TM," and "EXB-8150-65T" (manufactured by DIC Corporation) as active ester compounds containing a dicyclopentadiene-type diphenol structure, "EXB9416-70BK" (manufactured by DIC Corporation) as an active ester compound containing a naphthalene structure, and "EXB9416-70BK" (manufactured by DIC Corporation) as a phenolic compound. Examples of active ester compounds containing acetylated volac include "DC808" (manufactured by Mitsubishi Chemical Corporation), active ester compounds containing benzoylated phenol novolac include "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation), an active ester curing agent that is an acetylated phenol novolac, "DC808" (manufactured by Mitsubishi Chemical Corporation), and an active ester curing agent containing a phosphorus atom, "EXB-9050L-62M" (manufactured by DIC Corporation).

[0071] Regarding the compounding ratio of the active ester compound and the epoxy resin, the ratio (α / β) of the active ester equivalent (α) to the epoxy equivalent (β) is preferably 0.5 to 1.5, more preferably 0.8 to 1.2, and even more preferably 0.90 to 1.10. If the ratio is outside the above range, excess epoxy groups or active ester groups may remain in the system, which may deteriorate the properties in a high-temperature storage test (e.g., 150°C, 1000 hours) or a long-term reliability test under high-temperature and high-humidity conditions (e.g., temperature: 85°C, humidity: 85%).

[0072] [Phenol Resin] A phenol resin is a compound having two or more phenolic hydroxyl groups in the molecule. Examples of phenol resins include, but are not limited to, reaction products of phenols and aldehydes, reaction products of phenols and diene compounds, reaction products of phenols and ketones, reaction products of phenols and substituted biphenyls, reaction products of phenols and substituted phenyls, and reaction products of bisphenols and aldehydes. These may be used alone or in combination. Specific examples of the above raw materials are listed below, but are not limited to these. <Phenols> Phenol, alkyl-substituted phenol, aromatic-substituted phenol, hydroquinone, resorcinol, naphthol, alkyl-substituted naphthol, dihydroxybenzene, alkyl-substituted dihydroxybenzene, dihydroxynaphthalene, etc. <Aldehydes> Formaldehyde, acetaldehyde, alkyl aldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, furfural, etc. <Diene compounds> Dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene, divinylbiphenyl, diisopropenylbiphenyl, butadiene, isoprene, etc. <Ketones> Acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, fluorenone, etc. <Substituted biphenyls> 4,4'-bis(chloromethyl)-1,1'-biphenyl, 4,4'-bis(methoxymethyl)-1,1'-biphenyl, 4,4'-bis(hydroxymethyl)-1,1'-biphenyl, etc. <Substituted phenyls> 1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene, etc.

[0073] [Polyphenylene Ether Compound] From the viewpoint of heat resistance and electrical properties, the polyphenylene ether compound is preferably a polyphenylene ether compound having an ethylenically unsaturated bond, and more preferably a polyphenylene ether compound having an acrylic group, a methacrylic group, or a styrene structure. Commercially available products include SA-9000 (manufactured by SABIC Corporation, a polyphenylene ether compound having a methacrylic group) and OPE-2St 1200 (manufactured by Mitsubishi Gas Chemical Company, a polyphenylene ether compound having a styrene structure). The number average molecular weight (Mn) of the polyphenylene ether compound is preferably 500 to 5,000, more preferably 2,000 to 5,000, and even more preferably 2,000 to 4,000. If the molecular weight is less than 500, the heat resistance of the cured product tends to be insufficient. Furthermore, if the molecular weight is greater than 5,000, the melt viscosity increases, and sufficient fluidity cannot be obtained, which tends to result in molding defects. Furthermore, the reactivity decreases, the curing reaction takes a long time, and the amount of unreacted polyphenylene ether not incorporated into the curing system increases, which lowers the glass transition temperature of the cured product and reduces the heat resistance of the cured product. If the number average molecular weight of the polyphenylene ether compound is 500 to 5,000, it is possible to exhibit excellent heat resistance and moldability while maintaining excellent dielectric properties. The number average molecular weight here can be measured specifically using gel permeation chromatography or the like.

[0074] The polyphenylene ether compound may be one obtained by a polymerization reaction or one obtained by a redistribution reaction of a high-molecular-weight polyphenylene ether compound having a number-average molecular weight of approximately 10,000 to 30,000. Furthermore, these compounds may be used as raw materials and reacted with a compound having an ethylenically unsaturated bond, such as methacrylic acid chloride, acrylic acid chloride, or chloromethylstyrene, to impart radical polymerizability. A polyphenylene ether compound obtained by a redistribution reaction may be obtained, for example, by heating a high-molecular-weight polyphenylene ether compound in a solvent such as toluene in the presence of a phenolic compound and a radical initiator to cause a redistribution reaction. Such polyphenylene ether compounds obtained by a redistribution reaction are preferred because they have hydroxyl groups derived from the phenolic compound at both ends of the molecular chain that contribute to curing, thereby maintaining even higher heat resistance. Furthermore, functional groups can be introduced at both ends of the molecular chain even after modification with a compound having an ethylenically unsaturated bond. Furthermore, polyphenylene ether compounds obtained by a polymerization reaction are preferred because they exhibit excellent fluidity.

[0075] In the case of polyphenylene ether compounds obtained by polymerization, the molecular weight of the polyphenylene ether compound can be adjusted by adjusting the polymerization conditions, etc. In the case of polyphenylene ether compounds obtained by redistribution, the molecular weight of the resulting polyphenylene ether compound can be adjusted by adjusting the conditions, etc. of the redistribution reaction. More specifically, adjusting the amount of the phenolic compound used in the redistribution reaction can be considered. That is, the greater the amount of the phenolic compound, the lower the molecular weight of the resulting polyphenylene ether compound. In this case, poly(2,6-dimethyl-1,4-phenylene ether) or the like can be used as the high-molecular-weight polyphenylene ether compound that undergoes the redistribution reaction. Furthermore, the phenolic compound used in the redistribution reaction is not particularly limited, but preferred are, for example, polyfunctional phenolic compounds having two or more phenolic hydroxyl groups per molecule, such as bisphenol A, phenol novolac, and cresol novolac. These compounds may be used alone or in combination of two or more.

[0076] The content of the polyphenylene ether compound is not particularly limited, but is preferably 5 to 1,000 parts by mass, and more preferably 10 to 750 parts by mass, relative to 100 parts by mass of the curable resin composition. A content of the polyphenylene ether compound within the above range is preferable in that it not only has excellent heat resistance and the like, but also allows a cured product to be obtained that fully exhibits the excellent dielectric properties of the polyphenylene ether compound.

[0077] [Amine Resin] An amine resin is a compound having two or more amino groups in the molecule. Examples of the amine resin include diaminodiphenylmethane, diaminodiphenylsulfone, isophoronediamine, naphthalenediamine, aniline novolak (a reaction product of aniline and formalin), N-methylaniline novolak (a reaction product of N-methylaniline and formalin), orthoethylaniline novolak (a reaction product of orthoethylaniline and formalin), a reaction product of 2-methylaniline and formalin, a reaction product of 2,6-diisopropylaniline and formalin, a reaction product of 2,6-diethylaniline and formalin, a reaction product of 2-ethyl-6-ethylaniline and formalin, a reaction product of 2,6-dimethylaniline and formalin, and a reaction product obtained by reacting aniline and xylylene chloride. Examples of suitable aniline resins include, but are not limited to, aniline resins disclosed in Japanese Patent No. 6,429,862, reaction products of aniline and substituted biphenyls (such as 4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl), reaction products of aniline and substituted phenyls (such as 1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene), 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, reaction products of aniline and diisopropenylbenzene, and dimer diamine. These may be used alone or in combination.

[0078] [Compound containing an ethylenically unsaturated bond] The compound containing an ethylenically unsaturated bond is a compound having one or more ethylenically unsaturated bonds in the molecule that can be polymerized by heat or light, regardless of whether a polymerization initiator is used. Examples of compounds containing an ethylenically unsaturated bond include, but are not limited to, reaction products of the above-mentioned phenolic resins with ethylenically unsaturated bond-containing halogen-based compounds (chloromethylstyrene, allyl chloride, methallyl chloride, acrylic acid chloride, methacrylic acid chloride, etc.), reaction products of ethylenically unsaturated bond-containing phenols (2-allylphenol, 2-propenylphenol, 4-allylphenol, 4-propenylphenol, eugenol, isoeugenol, etc.) with halogen-based compounds (1,4-bis(chloromethyl)benzene, 4,4'-bis(chloromethyl)biphenyl, 4,4'-difluorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-dibromobenzophenone, cyanuric chloride, etc.), reaction products of epoxy resins or alcohols with (meth)acrylic acids (acrylic acid, methacrylic acid, etc.), and acid-modified products thereof. These compounds may be used alone or in combination.

[0079] [Isocyanate Resin] An isocyanate resin is a compound having two or more isocyanate groups in the molecule. Examples of the isocyanate resin include aromatic diisocyanates such as p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylene diisocyanate, m-xylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and naphthalene diisocyanate; aliphatic or alicyclic diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated xylene diisocyanate, norbornene diisocyanate, and lysine diisocyanate; polyisocyanates such as one or more biuret compounds of isocyanate monomers or isocyanate compounds obtained by trimerizing the above diisocyanate compounds; and polyisocyanates obtained by a urethanization reaction between the above isocyanate compounds and polyol compounds, but are not limited to these. These may be used alone or in combination.

[0080] [Polyamide Resin] Examples of polyamide resins include a reaction product of one or more of diamines, diisocyanates, and oxazolines with dicarboxylic acids, a reaction product of diamines with acid chlorides, and ring-opening polymerization products of lactam compounds. These may be used alone or in combination. Specific examples of the above-mentioned raw materials are listed below, but are not limited thereto.<Diamines> Ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, eicosanediamine, 2-methyl-1,5-diaminopentane, 2-methyl diamino-1,8-diaminooctane, dimer diamine, cyclohexanediamine, bis-(4-aminocyclohexyl)methane, bis(3-methyl-4-aminocyclohexyl)methane, xylylenediamine, norbornanediamine, isophoronediamine, bisaminomethyltricyclodecane, phenylenediamine, diethyltoluenediamine, naphthalenediamine, diaminodiphenylmethane, bis(4-amino-3,5-dimethylphenyl)methane, bis(4-amino-3,5-diethylphenyl)methane , 4,4'-methylenebis-o-toluidine, 4,4'-methylenebis-o-ethylaniline, 4,4'-methylenebis-2-ethyl-6-methylaniline, 4,4'-methylenebis-2,6-diisopropylaniline, 4,4-ethylenedianiline, diaminodiphenyl sulfone, diaminodiphenyl ether, 1,3-bis(3-aminophenoxy)benzene, 1,3-bis(4-aminophenoxy)benzene, 4,4-bis(4-aminophenoxy)biphenyl, 2,2-bis[4-(4-amino 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, aminobenzylamine, diaminobenzophenone, and the like.<Diisocyanates> benzene diisocyanate, toluene diisocyanate, 1,3-bis(isocyanatomethyl)benzene, 1,3-bis(isocyanatomethyl)cyclohexane, bis(4-isocyanatophenyl)methane, isophorone diisocyanate, 1,3-bis(2-isocyanato-2-propyl)benzene, 2,2-bis(4-isocyanatophenyl)hexafluoropropane, dicyclohexylmethane-4,4′-diisocyanate, and the like. <Dicarboxylic acids> oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, 5-hydroxyisophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodiumsulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, cyclohexanedicarboxylic acid, biphenyldicarboxylic acid, naphthalenedicarboxylic acid, benzophenonedicarboxylic acid, furandicarboxylic acid, 4,4'-dicarboxydiphenyl ether, 4,4'-dicarboxydiphenyl sulfide, and the like. <Acid chlorides> acetyl chloride, acrylic acid chloride, methacrylic acid chloride, malonyl chloride, succinic acid dichloride, diglycolyl chloride, glutaric acid dichloride, suberic acid dichloride, sebacic acid dichloride, adipic acid dichloride, dodecandioyl dichloride, azelayl chloride, 2,5-furandicarbonyl dichloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, trimesic acid chloride, bis(4-chlorocarbonylphenyl) ether, 4,4'-diphenyldicarbonyl chloride, 4,4'-azodibenzoyl dichloride, etc. <Lactams> ε-caprolactam, ω-undecanelactam, ω-laurolactam, etc.

[0081] [Polyimide Resin] Examples of polyimide resins include, but are not limited to, reaction products of the above diamines with the tetracarboxylic dianhydrides exemplified below. These may be used alone or in combination. <Tetracarboxylic Dianhydrides> 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2dicarboxylic anhydride, pyromellitic dianhydride, 1,2,3,4-benzenetetracarboxylic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride, 2,2',3,3'-benzophenonetetracarboxylic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, 3,3',4,4 '-diphenylsulfonetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethylidene-4,4'-diphthalic dianhydride, 2,2'-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'- Diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride, thio-4,4'-diphthalic dianhydride, sulfonyl-4,4'-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, 1,4-bis[2-(3,4- dicarboxyphenoxy)phenyl]benzene dianhydride, bis[3-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, bis[4-(3,4-dicarboxyphenoxy)phenyl]methane dianhydride, 2,2-bis[3-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride, bis(3,4-dicarboxyphenoxy)dimethylsilane dianhydride, 1,3-bis(3,4-dicarboxyphenyl)-1,1,3,3-tetramethyldisiloxane dianhydride, 2,3,6,7-naphthalenetetracarboxylic dianhydride, 1,4,5,8-naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, ethylenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1, 2,3,4-Cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane-1,2,3,4-tetracarboxylic dianhydride, cyclohexane-1,2,4,5-tetracarboxylic dianhydride, 3,3',4,4'-bicyclohexyltetracarboxylic dianhydride, carbonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic) dianhydride, methylene-4,4'-bis(cyclohexane-1,2-dicarboxylic) dianhydride, 1,2-ethylene-4,4'-bis(cyclohexane-1,2-dicarboxylic) 4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,1-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 2,2-propylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride hydrates, rel-[1S,5R,6R]-3-oxabicyclo[3,2,1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, ethylene glycol-bis-(3,4-dicarboxylic anhydride phenyl) ether, 4,4'-biphenylbis(trimellitic acid monoester acid anhydride), 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride, etc.

[0082] [Maleimide Compound] The curable resin composition of this embodiment may contain a maleimide compound. A maleimide compound is a compound having one or more maleimide groups in the molecule. Examples of the maleimide compound include 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, m-phenylene bismaleimide, 2,2'-bis[4-(4-maleimidophenoxy)phenyl]propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 4,4'-diphenylether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene), and Xyloc-type maleimide compounds (anilix maleimide, manufactured by Mitsui Chemicals Fine Co., Ltd.), biphenylaralkyl-type maleimide compounds (solidified by distilling off the solvent under reduced pressure from a resin solution containing the maleimide compound (M2) described in Example 4 of JP 2009-001783 A), bisaminocumylbenzene-type maleimide (maleimide compounds described in WO 2020 / 054601 A), maleimide compounds having an indane structure described in Japanese Patent No. 6629692 or WO 2020 / 217679, MATERIAL STAGE Vol. 18, No. 12 2019 "Continued Epoxy Resin CAS Number Story - Curing Agent CAS Number Memorandum No. 31 Bismaleimide (1)" and MATERIAL STAGE Vol. 19, No. 12 2019 Examples of suitable compounds include, but are not limited to, the maleimide compounds described in "Epoxy Resin CAS Number Story Continued - Hardener CAS Number Memorandum No. 32, Bismaleimide (2)" published in February 2019. These compounds may be used alone or in combination.

[0083] [Cyanate Ester Resin] Cyanate ester resins are cyanate ester compounds obtained by reacting a phenolic resin with a cyanogen halide. Specific examples include dicyanatobenzene, tricyanatobenzene, dicyanatonaphthalene, dicyanatobiphenyl, 2,2'-bis(4-cyanatophenyl)propane, bis(4-cyanatophenyl)methane, bis(3,5-dimethyl-4-cyanatophenyl)methane, 2,2'-bis(3,5-dimethyl-4-cyanatophenyl)propane, 2,2'-bis(4-cyanatophenyl)ethane, 2,2'-bis(4-cyanatophenyl)hexafluoropropane, bis(4-cyanatophenyl)sulfone, bis(4-cyanatophenyl)thioether, phenol novolac cyanate, and phenol-dicyclopentadiene co-condensates in which the hydroxyl groups have been converted to cyanate groups, but are not limited thereto. These compounds may be used alone or in combination. Furthermore, the cyanate ester compounds whose synthesis methods are described in JP-A-2005-264154 are particularly preferred as cyanate ester compounds because they have low moisture absorption, excellent flame retardancy, and excellent dielectric properties. The cyanate ester resin may contain a catalyst such as zinc naphthenate, cobalt naphthenate, copper naphthenate, lead naphthenate, zinc octoate, tin octoate, lead acetylacetonate, or dibutyltin maleate, in order to trimerize the cyanate group to form a sym-triazine ring, as necessary.

[0084] The catalyst is preferably used in an amount of 0.0001 to 0.10 parts by mass, and more preferably 0.00015 to 0.0015 parts by mass, per 100 parts by mass of the cyanate ester resin and the curable resin composition.

[0085] [Polybutadiene and Modified Products Thereof] Polybutadiene and modified products thereof are compounds having polybutadiene or a structure derived from polybutadiene in the molecule. The unsaturated bonds in the polybutadiene-derived structure may be partially or entirely converted to single bonds by hydrogenation. Examples of polybutadiene and modified products thereof include, but are not limited to, polybutadiene, hydroxyl-terminated polybutadiene, (meth)acrylate-terminated polybutadiene, carboxylic acid-terminated polybutadiene, amine-terminated polybutadiene, and styrene-butadiene rubber. These may be used alone or in combination. Of these, polybutadiene or styrene-butadiene rubber is preferred from the viewpoint of dielectric properties. Examples of styrene-butadiene rubber (SBR) include RICON-100, RICON-181, and RICON-184 (all manufactured by Cray Valley Chemical Industries, Ltd.) and 1,2-SBS (manufactured by Nippon Soda Co., Ltd.). Examples of polybutadienes include B-1000, B-2000, and B-3000 (all manufactured by Nippon Soda Co., Ltd.). The molecular weight of polybutadiene and styrene-butadiene rubber is preferably a weight-average molecular weight of 500 to 10,000, more preferably 750 to 7,500, and even more preferably 1,000 to 5,000. Below the lower limit of the above range, the amount of volatilization is high, making it difficult to adjust the solids content during prepreg production. Above the upper limit of the above range, compatibility with other curable resins deteriorates. In general, in the case of compounds containing heteroatoms such as oxygen and nitrogen, such as bismaleimides and polymaleimides, their polarity makes it difficult to ensure compatibility with low-polarity compounds, such as compounds composed mainly of hydrocarbons or compounds composed only of hydrocarbons. On the other hand, the compound of the present embodiment does not have a skeleton design in which heteroatoms such as oxygen and nitrogen are actively introduced, and therefore has excellent compatibility with materials having low polarity and low dielectric properties and compounds composed only of hydrocarbons.

[0086] [Polystyrene and Modified Polystyrene] Polystyrene and modified polystyrene are polystyrene or compounds having a structure derived from polystyrene in the molecule. Examples of polystyrene and modified products thereof include polystyrene, styrene-2-isopropenyl-2-oxazoline copolymers (Epocross RPS-1005, RP-61, both manufactured by Nippon Shokubai Co., Ltd.), SEP (styrene-ethylene-propylene copolymer: Septon 1020, manufactured by Kuraray Co., Ltd.), SEPS (styrene-ethylene-propylene-styrene copolymer: Septon 2002, Septon 2004F, Septon 2005, Septon 2006, Septon 2063, Septon 2104, all manufactured by Kuraray Co., Ltd.), SEEPS (styrene-ethylene / ethylene-propylene-styrene block copolymer: Septon 4003, Septon 4044, Septon 4055, Septon 4077, Septon 4099, all manufactured by Kuraray Co., Ltd.), SEBS (styrene-ethylene-butylene-styrene copolymer). Examples of suitable block copolymers include SEPTON 8004, SEPTON 8006, and SEPTON 8007L, all manufactured by Kuraray Co., Ltd.), SEEPS-OH (a styrene-ethylene / ethylene propylene-styrene block copolymer having a hydroxyl group at its terminal: SEPTON HG252, manufactured by Kuraray Co., Ltd.), SIS (styrene-isoprene-styrene block copolymer: SEPTON 5125 and SEPTON 5127, both manufactured by Kuraray Co., Ltd.), hydrogenated SIS (hydrogenated styrene-isoprene-styrene block copolymer: HYBRAR 7125F and HYBRAR 7311F, both manufactured by Kuraray Co., Ltd.), and SIBS (styrene-isobutylene-styrene block copolymer: SIBSTAR073T, SIBSTAR102T, and SIBSTAR103T (all manufactured by Kaneka Corporation), and SEPTON V9827 (manufactured by Kuraray Co., Ltd.)), but are not limited thereto. These may be used alone or in combination. Polystyrene and modified products thereof are preferably free of unsaturated bonds, since they have higher heat resistance and are less susceptible to oxidative degradation.Furthermore, there are no particular restrictions on the weight-average molecular weight of polystyrene and modified products thereof as long as it is 10,000 or more. However, if it is too large, compatibility with not only the polyphenylene ether compound but also low-molecular-weight components having a weight-average molecular weight of about 50 to 1,000 and oligomer components having a weight-average molecular weight of about 1,000 to 5,000 deteriorates, making it difficult to ensure mixing and solvent stability. Therefore, it is preferably about 10,000 to 300,000.

[0087] [Polyethylene and Modified Polyethylenes] Polyethylene and modified polyethylenes are compounds having polyethylene or a polyethylene-derived structure in the molecule. Examples of polyethylene and modified polyethylenes include, but are not limited to, ethylene-propylene copolymers, ethylene-styrene copolymers, ethylene-propylene-ethylidene norbornene copolymers (EBT: K-8370EM, K-9330M, etc., manufactured by Mitsui Chemicals, Inc.), ethylene-propylene-vinyl norbornene copolymers (VNB-EPT: PX-006M, PX-008M, PX-009M, etc., manufactured by Mitsui Chemicals, Inc.), ethylene-vinyl alcohol copolymers, and ethylene-vinyl acetate copolymers. From the viewpoint of improving heat resistance, it is preferable to use ethylene-propylene-ethylidene norbornene copolymers or ethylene-propylene-vinyl norbornene copolymers containing a crosslinkable structure. These may be used alone or in combination. There are no particular restrictions on the weight-average molecular weight of polyethylene and modified polyethylenes thereof as long as it is 10,000 or more. However, if it is too large, compatibility with not only the polyphenylene ether compound but also low-molecular-weight components having a weight-average molecular weight of about 50 to 1,000 and oligomer components having a weight-average molecular weight of about 1,000 to 5,000 deteriorates, making it difficult to ensure mixing and solvent stability. Therefore, it is preferably about 10,000 to 300,000.

[0088] [Benzoxazine Compound] Any benzoxazine compound may be used as long as it is a compound obtained by reacting a compound having a phenolic hydroxyl group, a compound having an amino group, or a compound having an aldehyde group. The compound having a phenolic hydroxyl group is not particularly limited, but for example, the above-mentioned phenolic resin, phenols (which may have a substituent such as an alkenyl group or an alkyl group), and bisphenols can be used. The compound having an amino group is not particularly limited, but the above-mentioned amine resin, diamine, and anilines (which may have a substituent such as an alkenyl group or an alkyl group) can be used. The aldehyde compound may be, for example, the above-mentioned aldehydes, but formaldehyde is preferably used. Commercially available benzoxazine compounds may be used, and examples thereof include benzoxazine P-d, Fa, and ALP-d (all manufactured by Shikoku Chemical Industry Co., Ltd.), JBZ-BA100N, JBZ-FA100N, JBZ-DP100N, JBZ-OP100N, JBZ-OP100D, and JBZ-OP100I (all manufactured by JFE Chemical Corporation), and BTBz (manufactured by Japan Material Technology Co., Ltd.).

[0089] The curable resin composition of this embodiment can be obtained by preparing the above components in a predetermined ratio, pre-curing the composition at 130 to 180°C for 30 to 500 seconds, and then post-curing the composition at 150 to 200°C for 2 to 15 hours, thereby allowing the curing reaction to proceed sufficiently and producing a cured product of this embodiment. Alternatively, the components of the curable resin composition can be uniformly dispersed or dissolved in a solvent or the like, and the solvent can be removed before curing.

[0090] The method for preparing the curable resin composition of this embodiment is not particularly limited, and the components may be simply mixed uniformly, or may be prepolymerized. For example, a mixture containing the compound of this embodiment is heated in the presence or absence of a curing accelerator or a polymerization initiator, and in the presence or absence of a solvent, to form a prepolymer. Similarly, compounds such as amine compounds, compounds having ethylenically unsaturated bonds, maleimide compounds, cyanate ester compounds, polybutadiene and modified products thereof, polystyrene and modified products thereof, inorganic fillers, and other additives may be added to form a prepolymer. The components may be mixed or prepolymerized using, for example, an extruder, kneader, or rolls in the absence of a solvent, or a reaction kettle equipped with a stirrer in the presence of a solvent.

[0091] The uniform mixing method involves kneading the components using a device such as a kneader, roll, or planetary mixer at a temperature within the range of 50 to 100°C to obtain a uniform resin composition. The resulting resin composition can be pulverized and then molded into cylindrical tablets using a molding machine such as a tablet machine, or into a granular powder or powder-like molded body. Alternatively, these compositions can be melted on a surface support and molded into a sheet with a thickness of 0.05 mm to 10 mm to obtain a molded curable resin composition. The resulting molded body is non-sticky at 0 to 20°C, and exhibits little loss of fluidity or curability even when stored at -25 to 0°C for one week or more. The resulting molded body can be molded into a cured product using a transfer molding machine or compression molding machine.

[0092] The curable resin composition of this embodiment can also be made into a varnish-like composition (hereinafter simply referred to as varnish) by adding an organic solvent. The curable resin composition of this embodiment can be dissolved in a solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, dimethylacetamide, or N-methylpyrrolidone, as needed, to form a varnish. This varnish is then impregnated into a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, or paper, and heated and dried to obtain a prepreg. This prepreg can then be hot-press molded to form a cured product of the curable resin composition of this embodiment. The solvent used in this case accounts for 10 to 70 wt %, preferably 15 to 70 wt %, of the mixture of the curable resin composition of this embodiment and the solvent. Furthermore, if the composition is in liquid form, a cured product containing carbon fiber can also be obtained directly, for example, by the RTM method.

[0093] The curable resin composition of this embodiment can also be used as a modifier for film-type compositions. Specifically, it can be used to improve flexibility and the like in the B-stage. Such a film-type resin composition can be obtained as a sheet-like adhesive by applying the curable resin composition of this embodiment as a varnish onto a release film, removing the solvent under heating, and then performing B-staging. This sheet-like adhesive can be used as an interlayer insulating layer in a multilayer substrate or the like.

[0094] The curable resin composition of this embodiment can also be used to obtain a prepreg by heating and melting it to reduce its viscosity and impregnating it into reinforcing fibers such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, and alumina fiber. Specific examples include glass fibers such as E-glass cloth, D-glass cloth, S-glass cloth, Q-glass cloth, spherical glass cloth, NE-glass cloth, and T-glass cloth; inorganic fibers other than glass; and organic fibers such as polyparaphenylene terephthalamide (Kevlar®, manufactured by DuPont), wholly aromatic polyamide, polyester, polyparaphenylene benzoxazole, polyimide, and carbon fiber, but are not limited thereto. The shape of the substrate is not particularly limited, but examples include woven fabric, nonwoven fabric, roving, and chopped strand mat. Known weaving methods for woven fabrics include plain weave, saddle-weave, and twill weave, and these known methods can be appropriately selected and used depending on the intended application and performance. Also preferred are woven fabrics that have been opened or glass woven fabrics that have been surface-treated with a silane coupling agent or the like. The thickness of the substrate is not particularly limited, but is preferably about 0.01 to 0.4 mm. Also, a prepreg can be obtained by impregnating reinforcing fibers with the varnish and drying the impregnated fibers by heating.

[0095] A laminate can also be manufactured using the prepreg. The laminate is not particularly limited as long as it comprises one or more prepregs, and may also have any other layers. The method for manufacturing the laminate can be any generally known method, and is not particularly limited. For example, when molding a metal foil-clad laminate, a multi-stage press, a multi-stage vacuum press, a continuous molding machine, an autoclave molding machine, or the like can be used. The prepregs are laminated together and then heated and pressure molded to obtain a laminate. The heating temperature is not particularly limited, but is preferably 65 to 300°C, and more preferably 120 to 270°C. The pressure applied is also not particularly limited, but if the pressure is too high, it becomes difficult to adjust the solid content of the resin in the laminate, resulting in unstable quality. If the pressure is too low, air bubbles will form and adhesion between the laminate layers will be poor. Therefore, a pressure of 2.0 to 5.0 MPa is preferred, and 2.5 to 4.0 MPa is more preferred. The laminate of this embodiment, having a layer made of metal foil, can be suitably used as a metal foil-clad laminate, as described below. The prepreg is cut into a desired shape and laminated with copper foil or the like as needed. The laminate is then heated and cured while applying pressure to the laminate by press molding, autoclave molding, sheet winding molding, or the like, to obtain an electrical and electronic laminate (printed wiring board) or a carbon fiber reinforced material.

[0096] The curable resin composition of this embodiment can also be made into a resin sheet. A method for obtaining a resin sheet from the curable resin composition of this embodiment includes, for example, applying the curable resin composition to a support film (support), drying the composition, and forming a resin composition layer on the support film. When the curable resin composition of this embodiment is used for a resin sheet, it is essential that the film softens under the lamination temperature conditions (70°C to 140°C) in the vacuum lamination method and exhibits fluidity (resin flow) that allows resin filling of via holes or through holes present in the circuit board simultaneously with lamination of the circuit board. It is preferable to blend the above components so as to exhibit such properties. The resulting resin sheet or circuit board (such as a copper-clad laminate) requires a uniform appearance in order to exhibit consistent performance at any location without causing a phenomenon in which locally different characteristic values ​​are exhibited due to phase separation or the like.

[0097] Here, the diameter of the through-holes in the circuit board is 0.1 to 0.5 mm, and the depth is 0.1 to 1.2 mm, and it is preferable to make it possible to fill the resin within this range. When laminating both sides of the circuit board, it is desirable to fill about half of the through-holes.

[0098] A specific method for producing the above-mentioned resin sheet includes preparing a resin composition varnished by blending an organic solvent therewith, applying the varnished resin composition to the surface of a support film (Y), and then drying the organic solvent by heating or blowing hot air or the like to form a resin composition layer (X).

[0099] The organic solvent used here preferably includes, for example, ketones such as acetone, methyl ethyl ketone, and cyclohexanone; acetate esters such as ethyl acetate, butyl acetate, cellosolve acetate, propylene glycol monomethyl ether acetate, and carbitol acetate; carbitols such as cellosolve and butyl carbitol; aromatic hydrocarbons such as toluene and xylene; dimethylformamide, dimethylacetamide, and N-methylpyrrolidone; and it is preferable to use the organic solvent in such a proportion that the nonvolatile content of the organic solvent is 30 to 60% by mass of the total.

[0100] The thickness of the resin composition layer (X) formed must be equal to or greater than the thickness of the conductor layer of the circuit board to which the resin composition layer (X) is laminated. Since the thickness of the conductor layer of the circuit board is in the range of 5 to 70 μm, the thickness of the resin composition layer (X) is preferably 10 to 100 μm. The resin composition layer (X) in this embodiment may be protected with a protective film described below. Protection with a protective film can prevent the adhesion of dust and scratches to the surface of the resin composition layer (X).

[0101] Examples of the support film and protective film include polyolefins such as polyethylene, polypropylene, and polyvinyl chloride; polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate; polycarbonate; polyimide; and even release paper and metal foils such as copper foil and aluminum foil. The support film and protective film may be subjected to a mud treatment, corona treatment, or release treatment. The thickness of the support film is not particularly limited, but is generally in the range of 10 to 150 μm, preferably 25 to 50 μm. The thickness of the protective film is preferably 1 to 40 μm.

[0102] The support film (Y) is peeled off after laminating the resin composition layer (X) onto a circuit board, or after forming an insulating layer by heat-curing the resin composition layer (X). If the support film (Y) is peeled off after the resin composition layer (X) constituting the resin sheet has been heat-cured, adhesion of dust and the like during the curing process can be prevented. When peeling off after curing the resin composition layer (X), the support film (Y) is previously subjected to a release treatment.

[0103] A multilayer printed circuit board can be produced from the resin sheet obtained as described above. For example, when the resin composition layer (X) is protected by a protective film, the protective film is peeled off, and then the resin composition layer (X) is laminated onto one or both sides of the circuit board so as to be in direct contact with the circuit board, for example, by a vacuum lamination method. The lamination method may be a batch method or a continuous method using a roll. If necessary, the resin sheet and the circuit board may be heated (preheated) before lamination. The lamination conditions are preferably a pressure bonding temperature (lamination temperature) of 70 to 140°C and a pressure bonding pressure of 1 to 11 kgf / cm. ２ (9.8 x 10 ４ ~107.9 x 10 ４ N / m ２ ), and lamination is preferably carried out under reduced air pressure of 20 mmHg (26.7 hPa) or less.

[0104] The curable resin composition of the present embodiment can be used to manufacture semiconductor devices, such as dual in-line packages (DIPs), quad flat packages (QFPs), ball grid arrays (BGAs), chip size packages (CSPs), small outline packages (SOPs), thin small outline packages (TSOPs), and thin quad flat packages (TQFPs).

[0105] The curable resin composition and its cured product according to this embodiment can be used in a wide range of fields. Specifically, they can be used in various applications such as molding materials, adhesives, composite materials, and paints. The cured product of the curable resin composition according to this embodiment exhibits excellent heat resistance and dielectric properties, and is therefore suitable for use in electrical and electronic components such as encapsulants for semiconductor elements, encapsulants for liquid crystal display elements, encapsulants for organic EL elements, and laminates (printed wiring boards, BGA substrates, build-up substrates, etc.), lightweight, high-strength structural composite materials such as carbon fiber reinforced plastics and glass fiber reinforced plastics, 3D printing, and the like.

[0106] The present invention will now be described in more detail with reference to examples. Unless otherwise specified, all parts are by weight. It should be noted that the present invention is not limited to these examples.

[0107] The various analytical methods used in the examples are described below. <GPC (Gel Permeation Chromatography) Analysis> Columns: SHODEX GPC KF-601 (2 columns), KF-602, KF-602.5, KF-603 Flow rate: 1.5 ml / min Column temperature: 40°C Solvent used: THF (tetrahydrofuran) Detector: RI (differential refractometer)

[0108] [Examples 1 to 7, Comparative Examples 1 to 3] Biphenylaralkyl maleimide resin M-1 (solidified by distilling off the solvent under reduced pressure from a resin solution containing the maleimide resin (M2) described in Synthesis Example 4 of JP 2009-001783 A), a polymerization inhibitor, and a polymerization initiator in the amounts shown in Table 1 were sandwiched between mirror-finished copper foil (T4X: manufactured by Fukuda Metal Copper Foil Co., Ltd.) and vacuum press-molded, followed by curing at 220°C for 2 hours. During this process, a piece of cushion paper with a thickness of 250 μm, cut out in the center to a size of 150 mm length and width, was used as a spacer. For evaluation, test pieces of the desired size were cut out using a laser cutter as needed, and evaluation was performed.

[0109] <Reactivity evaluation> DSC measurement was performed under the following conditions, and those in which only one peak was observed were evaluated as ○, while those in which two peaks were observed were evaluated as × because uncured components remained. Furthermore, when two peaks were observed, the calorific value of the peak on the higher temperature side was recorded as the residual calorific value. Differential scanning calorimeter: DSC6220 (manufactured by SII Nanotechnology Inc.) Measurement temperature range: 30 to 350°C Heating rate: 10°C / min Atmosphere: Nitrogen (30 mL / min) Sample amount: 5 mg

[0110] <Dielectric constant test and dielectric loss tangent test> Tests were conducted at 25°C using a 10 GHz cavity resonator manufactured by AET Corporation using a cavity resonator perturbation method. The test was conducted on a sample with a width of 1.7 mm, length of 100 mm, and a thickness of 0.2 mm. The evaluation results are shown in Table 1. In Table 1, "-" indicates that the measurement was not performed. Although DSC measurement was possible for Comparative Example 4, the cured product was brittle due to the low degree of cure, and therefore a sample for measuring the dielectric properties could not be obtained.

[0111]

[0112] ・MHQ: 2-methylhydroquinone ・BHT: 2,6-di-tert-butyl-4-methylphenol ・Phenothiazine: thiodiphenylamine ・HTEMPO: 4-hydroxy-2,2,6,6-tetramethylpiperidine 1-oxyl free radical ・DCP: dicumyl peroxide

[0113] [Examples 8-9, Comparative Example 7] <Storage Stability Evaluation> Biphenylaralkyl-type maleimide resin M-1 and a polymerization inhibitor were blended in the proportions shown in Table 2 and melted in a 500 mL four-neck flask at 120°C while blowing in nitrogen at a rate of 25 mL / min. Samples were taken at 6 and 12 hours while stirring at 120°C, and GPC was measured to compare the area percentages for retention times of 14 to 17 minutes. The GPC area percentage for retention times of 14 to 17 minutes at 12 hours divided by the GPC area percentage for retention times of 14 to 17 minutes at 6 hours was defined as the area change. The results are shown in Table 2.

[0114]

[0115] The results in Table 1 confirm that the curable resin composition of the present invention can give a cured product with excellent low dielectric properties without inhibiting the curing reaction. Furthermore, the results in Table 2 confirm that the composition has excellent storage stability at high temperatures.

[0116] The curable resin composition of the present invention is suitably used for electric and electronic parts such as semiconductor encapsulants, printed wiring boards, and build-up laminates.

Claims

1. A curable resin composition containing a compound represented by the following formula (1) and a compound having a phenolic hydroxyl group, wherein the content of the compound having a phenolic hydroxyl group is 0.0001 parts by mass or more and 0.13 parts by mass or less per 100 parts by mass of the compound represented by the following formula (1), wherein the curable resin composition consists solely of the compound represented by formula (1) as a maleimide resin, and X in the compound represented by formula (1) is one or more structures represented by the following formulas (B) to (H): 【Chemistry 1】 (In the above formula (1), X is a hydrocarbon having 1 to 25 carbon atoms, and each of the multiple R's independently represents a hydrocarbon group having 1 to 5 carbon atoms. Each m' is independently an integer of 1 to 3. n is the average number of repetitions and is a number of 1 to 20.) 【Chemistry 2】 (In the above formulas (B) to (H), each of the multiple R's independently represents a hydrocarbon group having 1 to 5 carbon atoms. Each of the multiple a's independently represents an integer of 1 to 4. Each of the multiple b's independently represents an integer of 1 to 3.)

2. A curable resin composition containing a compound represented by the following formula (1) and a compound having a phenolic hydroxyl group, wherein the content of the compound having a phenolic hydroxyl group is 0.0001 parts by mass or more and 0.13 parts by mass or less per 100 parts by mass of the compound represented by the following formula (1), wherein X in the compound represented by the formula (1) is one or more structures represented by the following formulas (B) to (H), and the curable resin composition does not contain an organic peroxide. 【Transformation 3】 (In the above formula (1), X is a hydrocarbon having 1 to 25 carbon atoms, and each of the multiple R's independently represents a hydrocarbon group having 1 to 5 carbon atoms. Each m' is independently an integer of 1 to 3. n is the average number of repetitions and is a number of 1 to 20.) 【Chemistry 4】 (In the above formulas (B) to (H), each of the multiple R's independently represents a hydrocarbon group having 1 to 5 carbon atoms. Each of the multiple a's independently represents an integer of 1 to 4. Each of the multiple b's independently represents an integer of 1 to 3.)

3. The curable resin composition according to claim 1, wherein the compound having a phenolic hydroxyl group is at least one selected from the group consisting of compounds represented by the following formula (2-1) and compounds represented by the following formula (2-2): 【Transformation 5】 (In the above formulas (2-1) and (2-2), there are multiple R １ , R ２ each independently represents a hydrocarbon group having 1 to 10 carbon atoms; p is an integer of 1 to 5; and q is an integer of 1 to 4.

4. A curable resin composition according to claim 2, wherein the compound having a phenolic hydroxyl group is one or more compounds selected from the group consisting of compounds represented by the following formula (2-1) and compounds represented by the following formula (2-2): 【Transformation 6】 (In the above formulas (2-1) and (2-2), each of the multiple R 1 s and R 2 s independently represents a hydrocarbon group having 1 to 10 carbon atoms. p is an integer of 1 to 5. q is an integer of 1 to 4.)

5. The curable resin composition according to claim 1, further comprising at least one selected from the group consisting of a curing accelerator, a polymerization initiator, an epoxy resin, an active ester compound, a phenolic resin, a polyphenylene ether compound, an amine resin, a compound having an ethylenically unsaturated bond, an isocyanate resin, a polyamide resin, a cyanate ester resin, a polyimide resin, polybutadiene and modified products thereof, polystyrene and modified products thereof, polyethylene and modified products thereof, and a benzoxazine compound.

6. The curable resin composition according to claim 2, further comprising one or more of a curing accelerator, a polymerization initiator, an epoxy resin, an active ester compound, a phenolic resin, a polyphenylene ether compound, an amine resin, a compound having an ethylenically unsaturated bond, an isocyanate resin, a polyamide resin, a maleimide resin, a cyanate ester resin, a polyimide resin, polybutadiene and modified products thereof, polystyrene and modified products thereof, polyethylene and modified products thereof, and a benzoxazine compound.

7. A cured product obtained by curing the curable resin composition according to claim 1 .

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