Curable resin composition, prepreg, and cured products thereof

Abstract

The present invention provides a curable resin composition that has excellent curing properties, electrical characteristics, flame retardancy, and mechanical characteristics, and an excellent linear expansion coefficient.　The curable resin composition contains a maleimide resin represented by formula (1) and a styrene compound represented by formula (2).　(In formula (1), R1 represents a hydrocarbon group having 1-20 carbon atoms and p is an integer of 0-4. X represents a hydrocarbon group having 2-15 carbon atoms. n is the average of the number of repeats and satisfies 1<n<5.)　(In formula (2), R2 represents a hydrocarbon group having 1-20 carbon atoms and q is an integer of 0-4.)

Description

Curable resin compositions, prepregs, and cured products thereof

[0001] The present invention relates to curable resin compositions, prepregs, and cured products thereof, and is suitably used in electrical and electronic components such as semiconductor encapsulants, printed circuit boards, build-up laminates, and optical waveguide devices, as well as lightweight, high-strength materials such as carbon fiber reinforced plastics and glass fiber reinforced plastics, and in 3D printing applications.

[0002] In recent years, the required characteristics of laminates used to mount electrical and electronic components have become broader and more sophisticated due to the expansion of their application fields. For example, while semiconductor chips were traditionally mounted on metal lead frames, high-performance semiconductor chips such as CPUs are increasingly mounted on laminates made of polymer materials. As the speed of CPUs and other components increases and clock frequencies rise, signal propagation delay and transmission loss become problems, requiring low dielectric constant and low dielectric loss tangent in the wiring boards.

[0003] With the advancement of communication technology, the momentum for 5G has been growing in recent years, and it is expected that communication devices using not only Sub6 but also frequencies above 10 GHz, especially quasi-millimeter wave and millimeter wave above 28 GHz, will increase explosively. As a result, substrate materials that can handle high frequencies are required for base stations, antennas, and communication devices. In these substrate materials, high dielectric properties (especially dielectric loss tangent) are considered important in order to prevent a decrease in transmission speed, and there is a demand for materials that can be used stably in these ranges.

[0004] In the semiconductor-related field, development of package substrates necessary for mounting chips is progressing, and these substrates are becoming thinner. In addition, in recent years, efforts have been made to increase the size of the mounted chips, and to increase density and integration, thereby increasing the speed and capacity of information transmission, and for this purpose, package substrates are also becoming larger. As package substrates become thinner and larger, the difference in thermal expansion coefficients between them and the chips can cause them to warp and potentially crack. Therefore, resin materials widely used for substrates are required to be low in thermal expansion coefficient (low CTE) or have excellent mechanical properties. In addition, such resin materials are required to have flame retardancy in the cured product, in addition to low CTE and electrical properties.

[0005] Therefore, epoxy resins, which have been used in various fields conventionally, are finding it difficult to meet the requirements for dielectric properties and coefficient of thermal expansion, and maleimide resins are being investigated as alternative materials.

[0006] Japanese Patent Publication No. 2023-013860, Japanese Patent Publication No. 61-000044, Japanese Patent Publication No. 63-035561

[0007] Maleimide resins widely use polyphenylene ether compounds as curing agents. However, while resin compositions consisting of maleimide resin and polyphenylene ether compounds exhibit excellent dielectric properties, their coefficient of thermal expansion, flame retardancy, and mechanical properties are still not entirely satisfactory. This is due to the large inter-functional group distances of the polyphenylene ether compounds.

[0008] Patent Document 1 discloses a resin composition comprising a bifunctional maleimide resin and a polyphenylene ether compound, but the coefficient of linear expansion is not sufficiently low.

[0009] The present invention has been made in view of the above circumstances, and aims to provide a curable resin composition that is excellent in curability, electrical properties, low coefficient of thermal expansion, flame retardancy, and mechanical properties.

[0010] The curable resin composition according to an embodiment of the present invention is a curable resin composition containing a maleimide resin represented by the following formula (1) and a styrene compound represented by the following formula (2).

[0011]

[0012] (In formula (1), R １ (where represents a hydrocarbon group with 1 to 20 carbon atoms, and p is an integer from 0 to 4. X represents a hydrocarbon group with 2 to 15 carbon atoms. n is the average number of repetitions, where 1 < n < 5.)

[0013]

[0014] (In formula (2), R ２ (where 'q' represents a hydrocarbon group with 1 to 20 carbon atoms, and 'q' is an integer from 0 to 4.)

[0015] According to the present invention, it is possible to provide a curable resin composition and a cured product thereof that are excellent in curability, electrical properties, low coefficient of thermal expansion, flame retardancy, and mechanical properties. In this application, "(numerical value 1) to (numerical value 2)" indicates that upper and lower limits are included.

[0016] This is the GPC chart for synthesis example 1. This is the GPC chart for synthesis example 2.

[0017] The curable resin composition of the present invention contains a maleimide resin represented by the following formula (1).

[0018]

[0019] In formula (1), R １ represents a hydrocarbon group having 1 to 20 carbon atoms, preferably a hydrocarbon group having 1 to 10 carbon atoms, more preferably a hydrocarbon group having 1 to 5 carbon atoms, and particularly preferably a methyl group. p is an integer from 0 to 4. X represents a hydrocarbon group having 2 to 15 carbon atoms, preferably a hydrocarbon group having 6 to 15 carbon atoms, and even more preferably a hydrocarbon group having 8 to 15 carbon atoms. n is the average value of the number of repetitions, where 1 < n < 5.

[0020] In formula (1) above, the value of n can be calculated from the number-average molecular weight obtained by gel permeation chromatography (GPC, detector: RI) of the maleimide resin, or from the area ratio of each of the separated peaks.

[0021] In formula (1) above, when n = 1, the solubility in the solvent is low, and when n is 5 or more, the flowability during molding deteriorates, and the properties of the cured product cannot be fully exhibited.

[0022] In formula (1) above, the content of n=1 by GPC analysis (RI) is preferably 98 area% or less, more preferably 20 to 90 area%, even more preferably 30 to 80 area%, and particularly preferably 40 to 80 area%. When the content of n=1 is 98 area% or less, heat resistance is good. Crystallinity is reduced and solvent solubility is good. On the other hand, when the lower limit of n=1 is 20 area% or more, the viscosity of the resin solution is reduced and impregnation is good. Also, since the solvent can be removed at a low temperature when the solid is extracted, self-polymerization is less likely to occur and handling is easy.

[0023] The maleimide resin represented by formula (1) exhibits good solvent solubility and improved low dielectric properties in its cured product by increasing the proportion of asymmetric structures with different orientations relative to the maleimide groups.

[0024] The softening point of the maleimide resin represented by formula (1) is preferably 50°C to 150°C, more preferably 80°C to 140°C, even more preferably 90°C to 130°C, and particularly preferably 95°C to 120°C. The melt viscosity at 150°C is 0.05 to 100 Pa·s, preferably 0.1 to 40 Pa·s.

[0025] The maleimide resin represented by formula (1) is more preferably represented by the following formula (3).

[0026]

[0027] In formula (3), R １ p and n have the same meaning as in formula (1). Each R 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, and more preferably a hydrogen atom or a methyl group. Ar represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocycle, and is particularly preferably one of the following formulas (A) to (C).

[0028]

[0029] In the above formula, R ３ represents a hydrocarbon group having 1 to 10 carbon atoms, preferably a hydrocarbon group having 1 to 5 carbon atoms, more preferably a hydrocarbon group having 1 to 3 carbon atoms. a is an integer of 0 to 3. * indicates the bonding position.

[0030] Hereinafter, the method for producing the maleimide resin represented by the above formula (1) will be described, but it is not limited to this production method.

[0031] [Method for producing aromatic amine resin] The maleimide resin represented by the above formula (1) can use an aromatic amine resin represented by the following formula (4) as a precursor.

[0032]

[0033] In formula (4), R １ , p, n, and X have the same meanings as in the above formula (1).

[0034] The aromatic amine resin represented by the above formula (4) may be synthesized by any known method. For example, under an arbitrary acid catalyst, in the presence or absence of a solvent, with anilines and any aldehydes such as benzaldehyde, naphthaldehyde, biphenylaldehyde, aryl halomethyls such as paraxylene dichloride, bischloromethyl biphenyl, bischloromethyl naphthalene, olefins such as diisopropenylbenzene, divinylbenzene, or alcohols such as di(α-hydroxyisopropyl)benzene, benzenedimethanol or compounds obtained by their dehydration, or by reaction with alkylbenzene formalin resins such as xylene formalin resin, mesitylene formalin resin.

[0035] The aromatic amine resin represented by the above formula (4) is particularly preferably represented by the following formula (5).

[0036]

[0037] In formula (5), R １ , p, and n have the same meanings as in the above formula (4).

[0038] The method for producing the aromatic amine resin represented by formula (5) is not particularly limited, and the n=1 compound of formula (4) can be obtained as the main component by reacting aniline with m-diisopropenylbenzene or m-di(α-hydroxyisopropyl)benzene at 180 to 250°C in the presence of an acidic catalyst. The n=1 compound contains three isomers: symmetrical compounds with the same orientation to two aniline molecules, such as 1,3-bis(p-aminocumyl)benzene and 1,3-bis(o-aminocumyl)benzene, and asymmetrical compounds with different orientations to two aniline molecules, such as 1-(o-aminocumyl)-3-(p-aminocumyl)benzene. Furthermore, n=2 to n=5 compounds are also produced as minor components, and in Patent Document 2, these are purified by crystallization to obtain 1,3-bis(p-aminocumyl)benzene with a purity of 98%. Furthermore, Patent Document 3 describes the synthesis of N,N'-(1,3-phenylene-di-(2,2-propylene)-di-p-phenylene)bismaleimide by maleimidizing 1,3-bis(p-aminocumyl)benzene to obtain a crystalline product. However, heating is required to dissolve this in a solvent, and if left at room temperature after heating, crystals precipitate within a few hours. Therefore, there is a possibility of crystal precipitation when preparing resin compositions, and the likelihood of crystallization increases as the concentration of N,N'-(1,3-phenylene-di-(2,2-propylene)-di-p-phenylene)bismaleimide increases. To create printed circuit boards and composite materials, glass cloth or carbon fibers are impregnated with varnish and then coated with resin. However, if crystals precipitate, the impregnation process becomes impossible. On the other hand, raising the temperature to maintain the dissolved state accelerates the reaction of the composition, shortening the pot life of the varnish.

[0039] When synthesizing the aromatic amine resin represented by formula (5) above, the acidic catalysts used include hydrochloric acid, phosphoric acid, sulfuric acid, formic acid, zinc chloride, ferric chloride, aluminum chloride, p-toluenesulfonic acid, methanesulfonic acid, and other acidic catalysts. In the present invention, protic acids such as hydrochloric acid, p-toluenesulfonic acid, and methanesulfonic acid are preferred. These may be used alone or in combination of two or more. The amount of catalyst used is preferably 1 to 12% by mass, more preferably 1 to 10% by mass, and particularly preferably 1 to 7% by mass, relative to 100% by mass of the aniline used. If the amount is greater than 12% by mass, the desired asymmetric structure compound will be less abundant, and compounds with a symmetric structure will be preferentially formed. On the other hand, if the amount is less than 1% by mass, not only will the reaction proceed slowly, but the reaction may not be completed, which is undesirable.

[0040] The reaction may be carried out using organic solvents such as toluene and xylene as needed, or without a solvent. For example, after adding an acidic catalyst to a mixed solution of anilines and a solvent, if the catalyst contains water, it is preferable to remove the water from the system by azeotropy. Then, diisopropenylbenzene or di(α-hydroxyisopropyl)benzene is added, and the reaction is carried out at 140 to 190°C, preferably 160 to 190°C, for 5 to 50 hours, preferably 5 to 30 hours, while removing the solvent from the system. If the reaction temperature is too high, the asymmetric structure will recombine after formation, and the target structure will be preferentially formed, preventing the desired solvent solubility and electrical properties from being exhibited. When di(α-hydroxyisopropyl)benzene is used, water is produced as a by-product, so it is removed from the system by azeotropic reaction with the solvent during heating. After the reaction is complete, the acidic catalyst is neutralized with an alkaline aqueous solution, and then a water-insoluble organic solvent is added to the oil layer and the washing is repeated until the wastewater becomes neutral, and then the solvent and excess anilines are removed under heating and reduced pressure. When activated clay or ion exchange resin is used, the reaction solution is filtered after the reaction is complete to remove the catalyst. Depending on the reaction temperature and the type of catalyst, diphenylamine may be produced as a by-product, so it is preferable to remove it as needed. The diphenylamine derivative is removed to 1% by mass or less, preferably 0.5% by mass or less, and more preferably 0.2% by mass or less, under high temperature and high vacuum, or by means such as steam distillation.

[0041] The anilines used in the production of the aromatic amine resin represented by formula (4) include aniline, 2-methylaniline, 3-methylaniline, 4-methylaniline, 2-ethylaniline, 3-ethylaniline, 4-ethylaniline, 2,3-dimethylaniline, 2,4-dimethylaniline, 2,5-dimethylaniline, 2,6-dimethylaniline, 3,4-dimethylaniline, 3,5-dimethylaniline, 2-propylaniline, 3-propylaniline, and 4-propylaniline. Examples include 2-isopropylaniline, 3-isopropylaniline, 4-isopropylaniline, 2-ethyl-6-methylaniline, 2-sec-butylaniline, 2-tert-butylaniline, 4-butylaniline, 4-sec-butylaniline, 4-tert-butylaniline, 2,3-diethylaniline, 2,4-diethylaniline, 2,5-diethylaniline, 2,6-diethylaniline, 2-isopropyl-6-methylaniline, and 4-aminobiphenyl. These may be used individually or in combination of two or more.

[0042] [Method for producing maleimide resin] The maleimide resin represented by formula (1) is obtained by adding or dehydrating and condensing the aromatic amine resin represented by formula (4) obtained by the above process with maleic acid or maleic anhydride (hereinafter also referred to as "maleic anhydride") in the presence of a solvent and a catalyst.

[0043] Since the water generated during the reaction must be removed from the system, it is preferable to use a solvent that is not water-soluble. Examples include aromatic solvents such as toluene and xylene, aliphatic solvents such as cyclohexane and n-hexane, ethers such as diethyl ether and diisopropyl ether, ester solvents such as ethyl acetate and butyl acetate, and ketone solvents such as methyl isobutyl ketone and cyclopentanone, but are not limited to these, and two or more may be used in combination.

[0044] Furthermore, an aprotic polar solvent can be used in combination with the aforementioned water-insoluble solvent. Examples include dimethyl sulfone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, and N-methyl-2-pyrrolidone, and two or more of these may be used in combination. When using an aprotic polar solvent, it is preferable to use one with a higher boiling point than the water-insoluble solvent used in combination.

[0045] Furthermore, the catalyst used in the reaction is an acidic catalyst and is not particularly limited, but examples include p-toluenesulfonic acid, hydroxy-p-toluenesulfonic acid, methanesulfonic acid, sulfuric acid, phosphoric acid, etc. The amount of acidic catalyst used is usually 0.1 to 10% by mass, preferably 1 to 5% by mass, relative to the aromatic amine resin.

[0046] For example, an aromatic amine resin represented by formula (4) is dissolved in toluene and N-methyl-2-pyrrolidone, maleic anhydride is added to produce amical, and then p-toluenesulfonic acid is added, and the reaction is carried out under reflux conditions while removing the water produced from the system.

[0047] Alternatively, maleic anhydride is dissolved in toluene, and under stirring, an N-methyl-2-pyrrolidone solution of the aromatic amine resin represented by formula (4) is added to produce amitic acid. Then, p-toluenesulfonic acid is added, and the reaction is carried out under reflux conditions while removing the water produced from the system.

[0048] Alternatively, maleic anhydride is dissolved in toluene, p-toluenesulfonic acid is added, and the N-methyl-2-pyrrolidone solution of the aromatic amine resin represented by formula (4) is added dropwise while stirring and refluxing, removing any azeotrope-forming water from the system and returning the toluene to the system as the reaction proceeds (first stage reaction).

[0049] In either method, maleic anhydride is typically used in an amount of 1.0 to 3.0 equivalents, preferably 1.2 to 2.0 equivalents, relative to the amino group of the aromatic amine resin represented by formula (4).

[0050] To reduce the amount of un-ring-closed amic acid, after the maleimide reaction listed above, water is added to the reaction solution to separate it into a resin solution layer and an aqueous layer. Excess maleic acid, maleic anhydride, aprotic polar solvent, and catalyst are dissolved in the aqueous layer, so these are removed by liquid-liquid extraction, and the same procedure is repeated to thoroughly remove excess maleic acid, maleic anhydride, aprotic polar solvent, and catalyst. The catalyst is then added back to the maleimide resin solution in the organic layer from which the excess maleic acid, maleic anhydride, aprotic polar solvent, and catalyst have been removed, and the dehydration and ring-closing reaction of the remaining amic acid is carried out again under heated reflux conditions to obtain a maleimide resin solution with a low acid value (the above is the second stage reaction).

[0051] The re-dehydration and ring-closing reaction takes typically 1 to 5 hours, preferably 1 to 3 hours, and the aforementioned aprotic polar solvent may be added as needed. After the reaction is complete, the mixture is cooled and washed with water repeatedly until the water becomes neutral. Then, the water is removed by azeotropic dehydration under reduced heating pressure, and the solvent may be removed by distillation or another solvent may be added to adjust the resin solution to the desired concentration, or the solvent may be completely removed to obtain the solid resin.

[0052] The functional group equivalent of the maleimide resin represented by formula (1) is preferably 250 g / eq. to 1000 g / eq., more preferably 260 g / eq. to 600 g / eq., and particularly preferably 270 g / eq. to 400 g / eq. Here, the functional group equivalent of the maleimide resin is the mass of a compound containing one equivalent of maleimide groups. For example, if a maleimide resin with a molecular weight of 250 has one maleimide group attached, the functional group equivalent is 250 g / eq. The functional group equivalent of the maleimide resin can be measured, for example, by the measurement method described in Japanese Patent Application Publication No. 2020-187012. Alternatively, if the maleimide equivalent can be calculated from the structural formula and the number of functional groups, that value may be used. If the functional group equivalent is less than 250 g / eq., the crosslinking density becomes too high, resulting in the cured product being unable to be molded or having inferior mechanical properties. On the other hand, if the functional group equivalent is greater than 1000 g / eq., the flame retardancy may deteriorate. When the functional group equivalent ratio is within the above range, a cured product can be obtained without deterioration of flame retardancy or mechanical properties.

[0053] The curable resin composition of the present invention contains a styrene compound represented by the following formula (2).

[0054]

[0055] In formula (2), R ２ represents a hydrocarbon group having 1 to 20 carbon atoms, preferably a hydrocarbon group having 1 to 10 carbon atoms, and more preferably a hydrocarbon group having 1 to 5 carbon atoms. Furthermore, the substitution position of the vinyl group is preferably the ortho position with respect to the oxygen atom. q is an integer from 0 to 4, and q = 0 is preferred.

[0056] The method for producing the styrene compound represented by formula (2) is not particularly limited and can be used to synthesize it, for example, by the method described in Chinese Patent Application Publication No. 109762115.

[0057] The functional group equivalent of the styrene compound represented by formula (2) is preferably 50 g / eq. to 400 g / eq., more preferably 70 g / eq. to 300 g / eq., and particularly preferably 90 g / eq. to 250 g / eq. Here, the functional group equivalent is the value obtained by dividing the molecular weight by the number of functional groups, and the functional group equivalent of the styrene compound is expressed as the molecular weight of the styrene compound divided by the number of styrene groups. If the functional group equivalent is less than 50 g / eq., the crosslinking density becomes too high, resulting in poor toughness of the cured product. On the other hand, if the functional group equivalent is greater than 400 g / eq., there is a risk of deterioration in heat resistance. When the functional group equivalent ratio is within the above range, a cured product can be obtained without deterioration in toughness or heat resistance.

[0058] In the curable resin composition of the present invention, the ratio of the maleimide resin represented by formula (1) to the styrene compound represented by formula (2) is preferably 50 to 90 parts by mass, more preferably 60 to 80 parts by mass, and particularly preferably 65 to 75 parts by mass, when the total amount of the maleimide resin represented by formula (1) and the styrene compound represented by formula (2) is 100 parts by mass. If the weight of the maleimide resin represented by formula (1) is less than 50 parts by mass, that is, if the amount of the styrene compound represented by formula (2) is too high, the crosslinking density will become too high, resulting in poor toughness of the resulting cured product or the inability to obtain a cured product. On the other hand, if the weight of the maleimide resin represented by formula (1) is more than 90 parts by mass, that is, if the amount of the styrene compound represented by formula (2) is too low, the flame retardancy of the resulting cured product will deteriorate. When the mass ratio of the maleimide resin represented by formula (1) to the styrene compound represented by formula (2) is within the above range, a cured product can be obtained without deterioration of toughness or flame retardancy.

[0059] [Curing Accelerator] The curability of the resin composition of the present invention can also be improved by adding a curing accelerator. Preferred curing accelerators are anionic curing accelerators that promote the curing reaction by generating anions upon irradiation with ultraviolet light or visible light or by heating, or cationic curing accelerators that promote the curing reaction by generating cations upon irradiation with ultraviolet light or visible light or by heating.

[0060] Examples of anionic curing accelerators include imidazoles such as 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4-methylimidazole. Examples of anionic curing accelerators other than the imidazole compounds include 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, tetrabutylammonium salt, triisopropylmethylammonium salt, trimethyldecanylammonium salt, cetyltrimethylammonium salt, and quaternary ammonium salts such as hexadecyltrimethylammonium hydroxide, but are not limited to these. Furthermore, these may be used individually or in combination of multiple types.

[0061] Examples of cationic curing accelerators include quaternary phosphonium salts such as triphenylbenzylphosphonium salt, triphenylethylphosphonium salt, and tetrabutylphosphonium salt (the counterions of the quaternary salts are halogens, organic acid ions, hydroxide ions, etc., with no particular preference, but organic acid ions and hydroxide ions are particularly preferred), cobalt naphthenate, copper naphthenate, lead acetylacetonate, copper acetylacetonate, dibutyltin maleate, manganese naphthenate, tin octoate, zinc carboxylates (zinc 2-ethylhexanoate, zinc stearate, zinc behenate, zinc myristate), and transition metal compounds (transition metal salts) such as zinc phosphate esters (zinc octyl phosphate, zinc stearyl phosphate), but are not limited to these. Furthermore, these may be used individually or in combination of multiple types.

[0062] The amount of curing accelerator used in the resin composition of the present invention is 0.01 to 5.0 parts by mass, as needed, when the total amount of the maleimide resin represented by formula (1) and the styrene compound represented by formula (2) is 100 parts by mass.

[0063] [Inorganic Fillers] The resin composition of the present invention may contain inorganic fillers. 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, or inorganic fillers made by shaping these into spheres or crushed forms. Furthermore, these may be used individually or in combination of multiple types.

[0064] When obtaining a curable resin composition for semiconductor encapsulation, 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. Furthermore, when obtaining a curable resin composition for interlayer insulating layer forming materials, copper-clad laminates, prepregs, RCCs, and other substrate materials, the amount of the above-mentioned 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.

[0065] [Polymerization Initiator] The curable resin composition of the present invention can also have its curability improved by adding a polymerization initiator. A polymerization initiator is a compound capable of polymerizing olefin functional groups such as ethylenically unsaturated bonds, and examples include olefin metathesis polymerization initiators, anionic polymerization initiators, cationic polymerization initiators, and radical polymerization initiators. Among these, it is preferable to use a radical polymerization initiator that has curability and appropriate stability. A radical polymerization initiator is a compound that generates radicals by irradiation with ultraviolet light or visible light or by heating, and initiates a chain polymerization reaction. Examples of radical polymerization initiators that can be used include organic peroxides, azo compounds, and benzopinacols, and it is preferable to use organic peroxides because they have little effect on curing temperature control, outgassing suppression, and the electrical properties of decomposition products.

[0066] Examples of the above 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-cumyl peroxyneodecanoate, t-butyl peroxyneodecanoate, t-butyl peroxypivalate, 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate, t-amyl peroxy-2-ethylhexanoate, and t-butyl peroxy Examples of alkyl peresters such as -oxy-2-ethylhexanoate, t-amyl peroxy-3,5,5-trimethylhexanoate, t-butyl peroxy-3,5,5-trimethylhexanoate, and t-amyl peroxybenzoate; peroxycarbonates such as di-2-ethylhexyl peroxydicarbonate, bis(4-t-butylcyclohexyl) peroxydicarbonate, t-butyl peroxyisopropyl carbonate, and 1,6-bis(t-butyl peroxycarbonyloxy)hexane; t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctoate, and lauroyl peroxide are examples, but are not limited to these. Furthermore, these may be used individually or in combination. Among the above organic peroxides, ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, and peroxycarbonates are preferred, with dialkyl peroxides being more preferred.

[0067] Examples of the above-mentioned azo compounds include, but are not limited to, azobisisobutyronitrile, 4,4'-azobis(4-cyanovaleric acid), and 2,2'-azobis(2,4-dimethylvaleronitrile). Furthermore, these compounds may be used individually or in combination.

[0068] 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, per 100 parts by mass of the curable resin composition. If the amount of polymerization initiator used is less than 0.01 parts by mass, the molecular weight may not elongate sufficiently during the polymerization reaction, and if it is more than 5 parts by mass, it may impair low dielectric properties such as dielectric constant and dielectric loss tangent.

[0069] [Polymerization Inhibitor] The curable resin composition of the present invention may contain a polymerization inhibitor. Including a polymerization inhibitor improves storage stability and allows control of the reaction initiation temperature. Controlling the reaction initiation temperature makes it easier to ensure fluidity, prevents impregnation of glass cloth and the like, and facilitates B-stage processes such as prepreg formation. If the polymerization reaction proceeds too far during prepreg formation, problems such as difficulty in lamination during the lamination process are likely to occur.

[0070] The amount of polymerization inhibitor used is preferably 0.008 to 1 part by mass, and more preferably 0.01 to 0.5 parts by mass, when the total amount of the maleimide resin represented by formula (1) and the styrene compound represented by formula (2) is 100 parts by mass.

[0071] Examples of polymerization inhibitors include phenol-based, sulfur-based, phosphorus-based, hindered amine-based, nitroso-based, and nitroxyl radical-based agents. Furthermore, polymerization inhibitors may be used individually or in combination of multiple types. Of these, phenol-based, hindered amine-based, nitroso-based, and nitroxyl radical-based agents are preferred in this invention.

[0072] Examples of the above phenolic polymerization inhibitors 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, and 2,4-bis[(octylthio)methyl]-o-c Monophenols such as resols, 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-hydroxyhydrocinnamamide), 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- Bisphenols such as calcium trimethyl-4-hydroxybenzylsulfonate ethyl, 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 include, but are not limited to, high molecular weight phenols such as 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.

[0073] Examples of sulfur-based polymerization inhibitors include, but are not limited to, dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate.

[0074] Examples of the phosphorus polymerization inhibitors mentioned above include triphenyl phosphite, diphenylisodecyl phosphite, phenyldiisodecyl phosphite, tris(nonylphenyl) phosphite, diisodecylpentaerythritol phosphite, tris(2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis(octadecyl) phosphite, cyclic neopentanetetraylbis(2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis(2,4-di-t-butyl-4-methylphenyl) phosphite, and bis[2- Examples include, but are not limited to, phosphites such as t-butyl-6-methyl-4-{2-(octadecyloxycarbonyl)ethyl}phenyl]hydrogen phosphite, 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.

[0075] Examples of the above hindered amine polymerization inhibitors include Adekastab LA-40MP, Adekastab LA-40Si, Adekastab LA-402AF, Adekastab LA-87, Adekastab LA-82, Adekastab LA-81, Adekastab LA-77Y, Adekastab LA-77G, Adekastab LA-72, Adekastab LA-68, Adekastab LA-63P, Adekastab LA-57, Adekastab Examples include, but are not limited to, LA-52, Chimassorb2020FDL, Chimassorb944FDL, Chimassorb944LD, Tinuvin622SF, TinuvinPA144, Tinuvin765, Tinuvin770DF, TinuvinXT55FB, Tinuvin111FDL, Tinuvin783FDL, Tinuvin791FB, etc.

[0076] Examples of the nitroso polymerization inhibitors mentioned above include, but are not limited to, p-nitrosophenol, N-nitrosodiphenylamine, and ammonium salts of N-nitrosophenylhydroxyamine (cuperone). Of these, ammonium salts of N-nitrosophenylhydroxyamine (cuperone) are preferred.

[0077] Examples of the above-mentioned nitroxyl radical polymerization inhibitors include, but are not limited to, di-tert-butylnitroxide, 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.

[0078] [Flame Retardant] The curable resin composition of the present invention may contain a flame retardant. Examples of flame retardants include halogen-based flame retardants, inorganic flame retardants (antimony compounds, metal hydroxides, nitrogen compounds, boron compounds, etc.), and phosphorus-based flame retardants, but phosphorus-based flame retardants are preferred from the viewpoint of achieving halogen-free flame retardancy. The phosphorus-based flame retardant may be of the reactive or additive type. Specific examples include phosphate esters such as trimethyl phosphate, triethyl phosphate, tricresyl phosphate, trixyllenyl phosphate, cresyl diphenyl phosphate, cresyl-2,6-dixyllenyl phosphate, 1,3-phenylenebis(dixyllenyl phosphate), 1,4-phenylenebis(dixyllenyl phosphate), and 4,4'-biphenyl(dixyllenyl 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 epoxy resin with the active hydrogen of the aforementioned phosphanes; and red phosphorus, but are not limited to these. Furthermore, these may be used individually or in combination of multiple types. Of the above example substances, phosphate esters, phosphans, or phosphorus-containing epoxy compounds are preferred, and 1,3-phenylenebis(dixyllenyl phosphate), 1,4-phenylenebis(dixyllenyl phosphate), 4,4'-biphenyl(dixyllenyl phosphate), or phosphorus-containing epoxy compounds are particularly preferred.

[0079] The flame retardant content is preferably in the range of 0.1 to 0.6 parts by mass, when the total amount of the maleimide resin represented by formula (1) and the styrene compound represented by formula (2) is 100 parts by mass. If the amount is less than 0.1 parts by mass, the flame retardancy may be insufficient, and if it is more than 0.6 parts by mass, it may adversely affect the low hygroscopicity and low dielectric properties of the cured product.

[0080] [Light Stabilizer] The curable resin composition of the present invention may use a light stabilizer. As the light stabilizer, hindered amine-based light stabilizers, particularly HALS, are preferred. Examples of HALS include: a reaction product 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; a reaction product 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 include, but are not limited to, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis(1-octyroxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidyl). Furthermore, these may be used individually or in combination of multiple types.

[0081] The amount of light stabilizer is preferably in the range of 0.001 to 0.1 parts by mass, when the total amount of the maleimide resin represented by formula (1) and the styrene compound represented by formula (2) is 100 parts by mass. If the amount is less than 0.001 parts by mass, it may be insufficient to exhibit the light stabilization effect, and if it is more than 0.1 parts by mass, it may adversely affect the low hygroscopicity and low dielectric properties of the cured product.

[0082] [Binder Resin] The curable resin composition of the present invention may also use a binder resin. Examples of binder resins include butyral resins, acetal resins, acrylic resins, epoxy-nylon resins, NBR-phenolic resins, epoxy-NBR resins, silicone resins, etc., but are not limited to these. Furthermore, these may be used individually or in combination of multiple types.

[0083] The amount of binder resin added is preferably within a range that does not impair the flame retardancy and heat resistance of the cured product. When the total amount of the maleimide resin represented by formula (1) and the styrene compound represented by formula (2) is 100 parts by mass, the amount of binder resin is preferably 0.05 to 50 parts by mass, and more preferably 0.05 to 20 parts by mass is used as needed.

[0084] [Additives] The curable resin composition of the present invention may contain additives. Examples of additives include 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.

[0085] The amount of additive added is preferably 1 part by mass or less, more preferably 0.7 parts by mass or less, per 100 parts by mass of the curable resin composition.

[0086] The curable resin composition of the present invention may further contain epoxy resins, active ester compounds, phenolic resins, polyphenylene ether compounds, amine resins, compounds having ethylenically unsaturated bonds, isocyanate resins, polyamide resins, maleimide compounds, cyanate ester resins, polyimide resins, polybutadiene and its modified counterparts, polystyrene and its modified counterparts, polyethylene and its modified counterparts, benzoxazine compounds, etc., and these may be used individually or in combination of multiple compounds. Among these compounds, it is preferable to include epoxy compounds, compounds having ethylenically unsaturated bonds, cyanate ester resins, polyphenylene ether compounds, polybutadiene and its modified counterparts, polystyrene and its modified counterparts, polyethylene and its modified counterparts, in order to balance heat resistance, adhesion, and dielectric properties. By including these compounds, the brittleness of the cured product can be improved and adhesion to metals can be enhanced, and cracks in the package can be suppressed during reliability tests such as solder reflow and thermal cycling. Unless otherwise specified, the amount of the above compound used is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and most preferably 3 parts by mass or less, relative to the total of the maleimide resin represented by formula (1) and the styrene compound represented by formula (2). The preferred lower limit is 0.1 parts by mass or more, more preferably 0.25 parts by mass or more, and even more preferably 0.5 parts by mass or more. By staying within the above range, the properties of the maleimide resin and the styrene compound can be utilized while adding the effects of each compound added. Examples of these components can be used as shown below.

[0087] [Epoxy Resin] The following are examples of preferred epoxy resins, but are not limited to these. The epoxy resin may be liquid or solid, and may be used alone or in combination of multiple types.

[0088] Examples of liquid epoxy resins include bisphenol A type epoxy resin, bisphenol F type epoxy resin, bisphenol AF type epoxy resin, naphthalene type epoxy resin, glycidyl ester type epoxy resin, glycidylamine type epoxy resin, phenol novolac type epoxy resin, alicyclic epoxy resin having an ester skeleton, cyclohexane type epoxy resin, cyclohexanedimethanol type epoxy resin, and epoxy resin having a butadiene structure. Specific examples include "RE310S", "RE410S" (both manufactured by Nippon Kayaku Co., Ltd., bisphenol A type epoxy resin), "RE303S", "RE304S", "RE403S", "RE404S" (all manufactured by Nippon Kayaku Co., Ltd., bisphenol F type epoxy resin), "HP4032", "HP4032D", "HP4032SS" (all manufactured by DIC Corporation, naphthalene type epoxy resin), "828US", "jER828EL", "825", "828EL" (all manufactured by Mitsubishi Chemical Corporation, bisphenol A type epoxy resin), "jE807", "1750" (both manufactured by Mitsubishi Chemical Corporation, bisphenol F type epoxy resin), and "jER152" (manufactured by Mitsubishi Chemical Corporation, phenol Examples include novolac-type epoxy resin, "630", "630LSD" (both 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), "Celoxide 2021P" (manufactured by Daicel Corporation, alicyclic epoxy resin with an ester skeleton), "PB-3600" (manufactured by Daicel Corporation, epoxy resin with a butadiene structure), "ZX1658", "ZX1658GS" (both manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., liquid 1,4-glycidylcyclohexane-type epoxy resin). These may be used individually or in combination of two or more types.

[0089] Preferred solid epoxy resins include, for example, bixylenol-type epoxy resin, naphthalene-type epoxy resin, naphthalene-type tetrafunctional epoxy resin, cresol novolac-type epoxy resin, dicyclopentadiene-type epoxy resin, trisphenol-type epoxy resin, naphthol-type epoxy resin, biphenyl-type epoxy resin, naphthylene ether-type epoxy resin, anthracene-type epoxy resin, bisphenol A-type epoxy resin, bisphenol AF-type epoxy resin, and tetraphenylethane-type epoxy resin.Specific examples include "HP4032H" (DIC Corporation, naphthalene-type epoxy resin), "HP-4700", "HP-4710" (both DIC Corporation, naphthalene-type tetrafunctional epoxy resin), "N-690" (DIC Corporation, cresol novolac-type epoxy resin), "N-695" (DIC Corporation, cresol novolac-type epoxy resin), "HP-7200" (DIC Corporation, dicyclopentadiene-type epoxy resin), "HP-7200", "HP-7200HH", "HP-7200H" (all DIC Corporation, dicyclopentadiene-type epoxy resin) Xylionic resin), "EXA-7311", "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" (both 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 epoxy resin), "XD-1000-2L", "XD-1000-L", "XD-1000-H" (all manufactured by Nippon Kayaku Co., Ltd., dicyclopentadiene epoxy resin), "ESN475V" (manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., naphthol epoxy resin), "ESN485" (manufactured by Nippon Steel & Sumitomo Metal Chemical Co., Ltd., naphthol novolac epoxy resin), "YX-4000H", "YX-4000", "YL6121" (all manufactured by Mitsubishi Chemical Corporation, biphenyl epoxy resin), "YX-4000HK" (manufactured by Mitsubishi Chemical Corporation, bixylenol) Examples include: (type epoxy resin), "YX-8800" (manufactured by Mitsubishi Chemical Corporation, anthracene-type epoxy resin), "PG-100", "CG-500" (manufactured by Osaka Gas Chemical 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), "jER1031S" (manufactured by Mitsubishi Chemical Corporation, tetraphenylethane-type epoxy resin), etc. These may be used individually or in combination of two or more types.

[0090] [Active Ester Compounds] Active ester compounds are compounds that contain at least one ester bond in their structure, and on both sides of the ester bond, aliphatic chains, aliphatic rings, or aromatic rings are bonded. Examples of active ester compounds include compounds having two or more highly reactive ester groups in one molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. They are obtained by a condensation reaction between at least one compound of a carboxylic acid compound, an acid chloride, or a thiocarboxylic acid compound and at least one compound of a hydroxy compound or a thiol compound. In particular, from the viewpoint of improving heat resistance, it is preferable that they be obtained from a carboxylic acid compound or an acid chloride and a hydroxy compound, and phenol compounds or naphthol compounds are preferred as the hydroxy compound. Active ester compounds may be used alone or in combination of two or more.

[0091] Examples of the carboxylic acid compounds mentioned above include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid.

[0092] Examples of the above-mentioned acid chlorides include acetyl chloride, acrylate chloride, methacrylate chloride, malonyl chloride, succinate dichloride, diglycolyl chloride, glutarate dichloride, suberate dichloride, sebacate dichloride, adipic acid dichloride, dodecanediol dichloride, azera oil chloride, 2,5-franzicarbonyl dichloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, trimesic acid chloride, bis(4-chlorocarbonylphenyl) ether, 4,4'-diphenyldicarbonyl chloride, and 4,4'-azodibenzoyl dichloride.

[0093] Examples of the above-mentioned phenol compounds and naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalein, 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, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolac, and phenol resins described later. Here, "dicyclopentadiene-type diphenol compound" refers to a diphenol compound obtained by the condensation of two molecules of phenol with one molecule of dicyclopentadiene.

[0094] Preferred examples of active ester compounds 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 International Publication No. 2020 / 095829, and the compounds disclosed in International Publication No. 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 represents a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene.

[0095] 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 naphthalene structure, and "EXB9416-70BK" (manufactured by DIC Corporation), and phenol novolat Examples of active ester compounds containing acetylated compounds include "DC808" (manufactured by Mitsubishi Chemical Corporation), examples of active ester compounds containing benzoylated compounds of phenol novolac include "YLH1026", "YLH1030", and "YLH1048" (manufactured by Mitsubishi Chemical Corporation), examples of active ester curing agents that are acetylated compounds of phenol novolac include "DC808" (manufactured by Mitsubishi Chemical Corporation), and examples of phosphorus atom-containing active ester curing agents include "EXB-9050L-62M" manufactured by DIC Corporation.

[0096] Regarding the blending ratio of the active ester compound and epoxy resin, the ratio of the active ester equivalent (α) to the epoxy equivalent (β) (α / 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 it falls outside the above range, there is a risk that excess epoxy groups or active ester groups will remain in the system, which may lead to deterioration of properties in high-temperature storage tests (e.g., 150°C, 1000 hours) or long-term reliability tests under high-temperature and high-humidity conditions (e.g., temperature: 85°C, humidity: 85%).

[0097] [Phenol Resins] Phenolic resins are compounds having two or more phenolic hydroxyl groups in their molecules. Examples of phenolic 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, reaction products of bisphenols and aldehydes, etc. Furthermore, these may be used individually or in combination of multiple types. Specific examples of the above raw materials are given 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, alkylaldehyde, 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. <Substitutive biphenyls> 4,4'-bis(chloromethyl)-1,1'-biphenyl, 4,4'-bis(methoxymethyl)-1,1'-biphenyl, 4,4'-bis(hydroxymethyl)-1,1'-biphenyl, etc. <Substitutive phenyls> 1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene, etc.

[0098] [Polyphenylene Ether Compounds] From the viewpoint of heat resistance and electrical properties, polyphenylene ether compounds are preferably polyphenylene ether compounds having ethylenically unsaturated bonds, and more preferably polyphenylene ether compounds having acrylic groups, methacrylic groups, or styrene structures. Commercially available products include SA-9000-111 (manufactured by SABIC, a polyphenylene ether compound having methacrylic groups), OPE-2St 1200 (manufactured by Mitsubishi Gas Chemical Co., Ltd., a polyphenylene ether compound having a styrene structure), and OPE-2St 2200 (manufactured by Mitsubishi Gas Chemical Co., Ltd., a polyphenylene ether compound having a styrene structure). The number average molecular weight (Mn) of the polyphenylene ether compound is preferably 500 to 5000, more preferably 2000 to 5000, and even more preferably 2000 to 4000. If the molecular weight is less than 500, the heat resistance of the cured product tends not to be sufficient. Furthermore, if the molecular weight is greater than 5000, the melt viscosity increases, and sufficient fluidity cannot be obtained, which tends to lead to molding defects. In addition, reactivity decreases, requiring a long time for the curing reaction, and the amount of unreacted material that is not incorporated into the curing system increases, lowering the glass transition temperature of the cured product and tending to reduce the heat resistance of the cured product. If the number average molecular weight of the polyphenylene ether compound is between 500 and 5000, it is possible to exhibit excellent heat resistance and moldability while maintaining excellent low dielectric properties. The number average molecular weight here can be specifically measured using gel permeation chromatography or the like.

[0099] Polyphenylene ether compounds may be obtained by polymerization reactions, or by redistributing high molecular weight polyphenylene ether compounds with a number average molecular weight of about 10,000 to 30,000. Alternatively, these may be used as raw materials and reacted with compounds having ethylenically unsaturated bonds, such as methacrylic chloride, acrylic chloride, and chloromethylstyrene, to impart radical polymerizability. Polyphenylene ether compounds obtained by redistribution reactions can 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 induce a redistribution reaction. Polyphenylene ether compounds obtained by such redistribution reactions are preferable because they have hydroxyl groups derived from phenolic compounds that contribute to curing at both ends of the molecular chain, thus maintaining even higher heat resistance, and because functional groups can be introduced to both ends of the molecular chain even after modification with a compound having ethylenically unsaturated bonds. Furthermore, polyphenylene ether compounds obtained by polymerization reactions are preferable because they exhibit excellent fluidity.

[0100] The molecular weight of polyphenylene ether compounds can be adjusted by adjusting polymerization conditions, etc., in the case of polyphenylene ether compounds obtained by polymerization reactions. In the case of polyphenylene ether compounds obtained by redistribution reactions, the molecular weight of the resulting polyphenylene ether compound can be adjusted by adjusting the conditions of the redistribution reaction, etc. More specifically, this can be done by adjusting the amount of phenolic compound used in the redistribution reaction. That is, the higher the amount of phenolic compound used, the lower the molecular weight of the resulting polyphenylene ether compound. In this case, poly(2,6-dimethyl-1,4-phenylene ether) 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 polyfunctional phenolic compounds having two or more phenolic hydroxyl groups in the molecule, such as bisphenol A, phenol novolac, and cresol novolac, are preferably used. These may be used individually or in combination of two or more.

[0101] The content of the polyphenylene ether compound is not particularly limited, but is preferably 5 to 1000 parts by mass, and more preferably 10 to 750 parts by mass, when the total amount of maleimide resin and cyanate ester compound is 100 parts by mass. When the content of the polyphenylene ether compound is within the above range, it is preferable not only to obtain a cured product that has excellent heat resistance and the like, but also to obtain a cured product that fully exhibits the excellent dielectric properties of the polyphenylene ether compound.

[0102] [Amine Resins] Amine resins are compounds having two or more amino groups in their molecule. Examples of amine resins include diaminodiphenylmethane, diaminodiphenylsulfone, isophoronediamine, naphthalenediamine, aniline novolac (reaction product of aniline and formalin), N-methylaniline novolac (reaction product of N-methylaniline and formalin), orthoethylaniline novolac (reaction product of orthoethylaniline and formalin), reaction product of 2-methylaniline and formalin, reaction product of 2,6-diisopropylaniline and formalin, reaction product of 2,6-diethylaniline and formalin, reaction product of 2-ethyl-6-ethylaniline and formalin, reaction product of 2,6-dimethylaniline and formalin, and those obtained by the reaction of aniline with xylylene chloride. Examples of aniline resins include, but are not limited to, aniline and substituted biphenyls (such as 4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl) as described in Japanese Patent Publication No. 6429862, 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, aniline and diisopropenylbenzene, and dimer amines. Furthermore, these may be used individually or in combination.

[0103] [Compounds containing ethylenically unsaturated bonds] Compounds containing ethylenically unsaturated bonds are compounds that have one or more ethylenically unsaturated bonds in their molecule, which can be polymerized by heat or light, regardless of whether a polymerization initiator is used or not. Examples of compounds containing ethylenically unsaturated bonds include the reaction product of the phenol resin and halogenated compounds containing ethylenically unsaturated bonds (chloromethylstyrene, allyl chloride, methallyl chloride, acrylate chloride, methacrylate chloride, etc.), and phenols containing ethylenically unsaturated bonds (2-allylphenol, 2-propenylphenol, 4-allylphenol, 4-propenylphenol, eugenol, isoeugenol, etc.) and halogenated compounds (1,4-bis(chloromethyl)benzene, 4,4'-bis( Reaction products of chloromethyl)biphenyl, 4,4'-difluorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-dibromobenzophenone, cyanuryl chloride, etc.; reaction products of epoxy resins or alcohols with (meth)acrylic acids (acrylic acid, methacrylic acid, etc.) and acid-modified products thereof; poly(arylene ether) polymers (HC-G0037, HC-G0024, HC-G0030, HC-G0038, all manufactured by JSR Corporation. These may contain monomer units containing pyridazine, pyrimidine, or pyrazine groups.) Reaction products of fluorenes or indenes with halogen compounds containing ethylenically unsaturated bonds (chloromethylstyrene, allyl chloride, methyl chloride, acrylate chloride, methacrylate chloride, etc.), compounds described in Japanese Patent No. 6951829, copolymers containing divinylbenzene as a constituent unit (ODV-XET(X3), ODV-XET(X4), ODV-XET(X5), all manufactured by Nippon Steel Chemical & Material Co., Ltd.), styrene, vinyltoluene, ethyl vinylbenzene Examples include, but are not limited to, benzene, vinylnaphthalene, vinylbiphenyl, vinylfluorene, divinylbenzene, divinylnaphthalene, divinylbiphenyl, divinylfluorene, BVPM (bis(vinylphenyl)methane), BVPE (bis(vinylphenyl)ethane), BVPH (bis(vinylphenyl)hexane), trivinylcyclohexane, and thermosetting cycloolefin copolymers (Mitsui Chemicals: GigaFreak, Zeon Corporation: TU-01A). These can be used individually or in combination.

[0104] [Maleimide Compounds] The curable resin composition of the present invention may contain maleimide compounds. Maleimide compounds are compounds having one or more maleimide groups in their molecule. Examples of maleimide compounds include 4,4'-diphenylmethanebismaleimide, polyphenylmethanemaleimide, m-phenylenebismaleimide, 2,2'-bis[4-(4-maleimoidphenoxy)phenyl]propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethanebismaleimide, 4-methyl-1,3-phenylenebismaleimide, 4,4'-diphenyletherbismaleimide, 4,4'-diphenylsulfonebismaleimide, 1,3-bis(3-maleimoidphenoxy)benzene, 1,3-bis(4-maleimide Midophenoxybenzene, Zyloc-type maleimide compounds (anilix maleimide, manufactured by Mitsui Chemicals Fine Co., Ltd.), biphenylaralkyl-type maleimide compounds (solidified by solvent distillation under reduced pressure of a resin solution containing the maleimide compound (M2) described in Example 4 of Japanese Patent Publication No. 2009-001783), bisaminocumylbenzene-type maleimide (maleimide compound described in International Publication No. 2020 / 054601), maleimide compounds having an indan structure described in Japanese Patent No. 6629692 or International Publication No. 2020 / 217679, MATERIAL STAGE Vol. 18, No. 12 2019 "Continued Epoxy Resin CAS Number Story - Curing Agent CAS Number Memo No. 31 Bismaleimide (1)" and MATERIAL STAGE Vol. 19, No. 2. Maleimide compounds, etc., as described in "Continued Story of Epoxy Resin CAS Numbers - Memorandum on CAS Numbers for Hardeners, Part 32: Bismaleimide (2)" (2019), are examples, but are not limited to these. Furthermore, these may be used individually or in combination of multiple types.

[0105] [Cyanate Ester Resins] Cyanate ester resins are cyanate ester compounds obtained by reacting phenol resins with cyanide halides. Specific examples include, but are not limited to, dicyanate benzene, tricyanate benzene, dicyanate naphthalene, dicyanate biphenyl, 2,2'-bis(4-cyanatephenyl)propane, bis(4-cyanatephenyl)methane, bis(3,5-dimethyl-4-cyanatephenyl)methane, 2,2'-bis(3,5-dimethyl-4-cyanatephenyl)propane, 2,2'-bis(4-cyanatephenyl)ethane, 2,2'-bis(4-cyanatephenyl)hexafluoropropane, bis(4-cyanatephenyl)sulfone, bis(4-cyanatephenyl)thioether, phenol novolac cyanate, and phenol-dicyclopentadiene cocondensates in which the hydroxyl groups have been converted to cyanate groups. Furthermore, these may be used individually or in combination of multiple types. In addition, the cyanate ester compound whose synthesis method is described in Japanese Patent Application Publication No. 2005-264154 is particularly preferred as a cyanate ester compound because it has excellent low hygroscopicity, flame retardancy, and dielectric properties. The cyanate ester resin may also contain catalysts 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 and form a sym-triazine ring as needed.

[0106] It is preferable to use the catalyst in an amount of 0.0001 to 0.10 parts by mass, preferably 0.00015 to 0.0015 parts by mass, per 100 parts by mass of the curable resin composition.

[0107] [Isocyanate resin] An isocyanate resin is a compound that has two or more isocyanate groups in its molecule. Examples of isocyanate resins include, but are not limited to, aromatic diisocyanates such as p-phenylenediisocyanate, m-phenylenediisocyanate, p-xylenediisocyanate, m-xylenediisocyanate, 2,4-tollylenediisocyanate, 2,6-tollylenediisocyanate, 4,4'-diphenylmethanediisocyanate, and naphthalenediisocyanate; aliphatic or alicyclic diisocyanates such as isophorone diisocyanate, hexamethylenediisocyanate, 4,4'-dicyclohexylmethanediisocyanate, hydrogenated xylenediisocyanate, norbornenediisocyanate, and lysinediisocyanate; biuret compounds of one or more isocyanate monomers; or isocyanates obtained by trimerizing the above diisocyanate compounds; and polyisocyanates obtained by urethane reaction between the above isocyanate compounds and polyol compounds. Furthermore, these can be used individually or in combination.

[0108] [Polyamide Resins] Examples of polyamide resins include reaction products of one or more of diamines, diisocyanates, or oxazolines with dicarboxylic acids, reaction products of diamines and acid chlorides, and ring-opening polymers of lactam compounds. These may be used individually or in combination of multiple types. Specific examples of the above raw materials are given below, but the material is not limited to these.<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 1,8-diaminooctane, dimeramine, 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, diaminodiphenylsulfone, 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 [phenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]sulfone, 2,2-bis(3-amino-4-hydroxyphenyl)propane, 2,2-bis(4-aminophenyl)hexafluoropropane, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, 9,9-bis(4-aminophenyl)fluorene, 2,7-diaminofluorene, aminobenzylamine, diaminobenzophenone, etc.<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, etc. <Dicarboxylic acids> Oxalic acid, malonic acid, succicic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanediic acid, dodecanediic acid, terephthalic acid, isophthalic acid, 5-hydroxyisophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodium sulfoisophthalic acid, hexahydroterephthalic acid, hexahydroisophthalic acid, cyclohexanedicarboxylic acid, biphenyldicarboxylic acid, naphthalenedicarboxylic acid, benzophenonedicarboxylic acid, francicarboxylic acid, 4,4'-dicarboxydiphenyl ether, 4,4'-dicarboxydiphenyl sulfide, etc. <Acid Chlorides> Acetyl chloride, acrylate chloride, methacrylate chloride, malonyl chloride, succinate dichloride, diglycolyl chloride, glutarate dichloride, suberate dichloride, sebacate dichloride, adipic acid dichloride, dodecane dioyl chloride, azera oil chloride, 2,5-franzicarbonyl dichloride, phthaloyl chloride, isophthaloyl chloride, terephthaloyl chloride, trimesinate chloride, bis(4-chlorocarbonylphenyl) ether, 4,4'-diphenyl dicarbonyl chloride, 4,4'-azodibenzoyl dichloride, etc. <Lactams> ε-caprolactam, ω-undecane lactam, ω-laurolactam, etc.

[0109] [Polyimide Resin] Examples of polyimide resins include, but are not limited to, the reaction products of the diamine and the tetracarboxylic dianhydrides exemplified below. Furthermore, these may be used individually or in combination of multiple types. <Tetracarboxylic Dianhydrides> 4,4'-(hexafluoroisopropylidene)diphthalic anhydride, 5-(2,5-dioxotetrahydro-3-furanyl)-3-methyl-cyclohexene-1,2-dicarboxylic 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 '-diphenylsulfontetracarboxylic acid dianhydride, 2,2',3,3'-biphenyltetracarboxylic acid dianhydride, methylene-4,4'-diphthalic acid dianhydride, 1,1-ethylidene-4,4'-diphthalic acid dianhydride, 2,2'-propyridene-4,4'-diphthalic acid dianhydride, 1,2-ethylene-4,4'-diphthalic acid dianhydride, 1,3-trimethylene-4,4'-diphthalic acid dianhydride, 1,4-tetramethylene-4,4'-diphthalic acid dianhydride, 1,5-pentamethylene-4,4'- Diphthalic acid dianhydride, 4,4'-oxydiphthalic acid dianhydride, thio-4,4'-diphthalic acid dianhydride, sulfonyl-4,4'-diphthalic acid 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- [Dicarboxyphenyl)-2-propyl]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 acid dianhydride, 1,4,5,8-naphthalenetetracarboxylic acid dianhydride, 1,2,5,6-naphthalenetetracarboxylic acid dianhydride, 3,4,9,10-perylenetetracarboxylic acid dianhydride, 2,3,6,7-anthracenetetracarboxylic acid dianhydride, 1,2,7,8-phenanthrenetetracarboxylic acid dianhydride, ethylenetetracarboxylic acid dianhydride, 1,2,3,4-butanetetracarboxylic acid 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 acid) dianhydride, methylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 1,2-ethylene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride (Bonic acid) dianhydride, 1,1-ethylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, 2,2-propyridene-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]octo-7-ene-2,3,5,6-tetracarboxylic acid dianhydride Water compounds, 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 acid anhydride, ethylene glycol-bis-(3,4-dicarboxylic acid anhydride phenyl) ether, 4,4'-biphenylbis(trimellitic acid monoester anhydride), 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride, etc.

[0110] [Polybutadiene and its modified products] Polybutadiene and its modified products are compounds that have polybutadiene or a structure derived from polybutadiene within their molecule. The structure derived from polybutadiene may have some or all of its unsaturated bonds converted to single bonds by hydrogenation. Examples of polybutadiene and its modified products include, but are not limited to, polybutadiene, hydroxyl-terminated polybutadiene, terminally (meth)acrylated polybutadiene, carboxylic acid-terminated polybutadiene, amine-terminated polybutadiene, and styrene-butadiene rubber. Furthermore, these may be used individually 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, RICON-184 (all manufactured by Clay Valley Corporation), and 1,2-SBS (manufactured by Nippon Soda Co., Ltd.). Examples of polybutadiene include B-1000, B-2000, and B-3000 (all manufactured by Nippon Soda Co., Ltd.). The weight-average molecular weight of polybutadiene and styrene-butadiene rubber is preferably 500 to 10000, more preferably 750 to 7500, and even more preferably 1000 to 5000. Below the lower limit of the above range, the volatility is high, making it difficult to adjust the solid content during prepreg preparation, and above the upper limit of the above range, the compatibility with other curable resins deteriorates. In general, in the case of compounds containing heteroatoms such as oxygen and nitrogen, such as bismaleimide and polymaleimide, it is difficult to ensure compatibility with low-polarity compounds such as compounds mainly composed of hydrocarbons or compounds consisting only of hydrocarbons, due to their polarity. On the other hand, the maleimide resin represented by formula (1) does not have a framework design that actively incorporates heteroatoms such as oxygen and nitrogen, and therefore exhibits excellent compatibility with materials that have low polarity and low dielectric properties, as well as with compounds composed solely of hydrocarbons.

[0111] [Polystyrene and its modified products] Polystyrene and its modified products are polystyrene or compounds that have a structure derived from polystyrene within their molecules. Examples of polystyrene and its modified products include polystyrene, styrene-2-isopropenyl-2-oxazoline copolymer (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.), and 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 block copolymer: Septon 8004, Septon 8006, Septon 8007L, all manufactured by Kuraray Co., Ltd.), SEEPS-OH (compound having hydroxyl groups at the ends of styrene-ethylene / ethylene-propylene-styrene block copolymer: Septon HG252, manufactured by Kuraray Co., Ltd.), SIS (styrene-isoprene-styrene block copolymer: Septon 5125, Septon 5127, all manufactured by Kuraray Co., Ltd.), Hydrogenated SIS (hydrogenated styrene-isoprene-styrene block copolymer: Hybrar 7125F, Hybrar 7311F Examples include, but are not limited to, polystyrene-isobutylene-styrene block copolymers (SIBS: SIBSTAR073T, SIBSTAR102T, SIBSTAR103T (all manufactured by Kaneka Corporation), Septon V9827 (manufactured by Kuraray Co., Ltd.)), etc. Furthermore, these may be used individually or in combination. Polystyrene and its modified products are preferable to have those without unsaturated bonds because they have higher heat resistance and are less susceptible to oxidative degradation.Furthermore, while there are no particular restrictions on the weight-average molecular weight of polystyrene and its modified products as long as it is 10,000 or more, if it is too high, the compatibility with polyphenylene ether compounds, as well as low molecular weight components with a weight-average molecular weight of about 50 to 1,000 and oligomer components with 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 preferable that the weight-average molecular weight be around 10,000 to 300,000.

[0112] [Polyethylene and Modified Products thereof] Polyethylene and modified products thereof refer to polyethylene or compounds having a structure derived from polyethylene within their molecules. Examples of polyethylene and modified products thereof include, but are not limited to, ethylene-propylene copolymers, ethylene-styrene copolymers, ethylene-propylene-ethylidene norbornene copolymers (Mitsui Chemicals, Ltd. EBT: K-8370EM, K-9330M, etc.), ethylene-propylene-vinyl norbornene copolymers (Mitsui Chemicals, Ltd. VNB-EPT: PX-006M, PX-008M, PX-009M, etc.), 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 and ethylene-propylene-vinyl norbornene copolymers that contain a crosslinkable structure. Furthermore, these may be used individually or in combination of multiple types. While there are no particular restrictions on the weight-average molecular weight of polyethylene and its modified products as long as it is 10,000 or more, if it is too high, the compatibility with polyphenylene ether compounds, as well as low molecular weight components with a weight-average molecular weight of about 50 to 1,000 and oligomer components with 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 preferable that the molecular weight be around 10,000 to 300,000.

[0113] [Benzoxazine Compounds] Any benzoxazine compound may be used as 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 aforementioned phenolic resins, phenols (which may have substituents such as alkenyl groups or alkyl groups), and bisphenols can be used. The compound having an amino group is not particularly limited, but for example, the aforementioned amine resins, diamines, and anilines (which may have substituents such as alkenyl groups or alkyl groups) can be used. As for the aldehyde compound, for example, the aforementioned aldehydes can be used, but formaldehyde is preferred. Commercially available benzoxazine compounds may be used, including benzoxazine P-d, F-a, ALP-d (all manufactured by Shikoku Chemicals Co., Ltd.), JBZ-BA100N, JBZ-FA100N, JBZ-DP100N, JBZ-OP100N, JBZ-OP100D, JBZ-OP100I (all manufactured by JFE Chemical Corporation), and BTBz (manufactured by Nippon Materials Technology Co., Ltd.).

[0114] The curable resin composition of the present invention is obtained by preparing the above components in predetermined proportions, pre-curing at 130 to 180°C for 30 to 500 seconds, and then post-curing at 150 to 200°C for 2 to 15 hours to allow the curing reaction to proceed sufficiently and obtain the cured product of the present invention. Alternatively, the components of the curable resin composition can be uniformly dispersed or dissolved in a solvent, and then cured after removing the solvent.

[0115] The method for preparing the curable resin composition of the present invention is not particularly limited, but may be done by simply uniformly mixing each component or by prepolymerizing them. Mixing or prepolymerizing the components can be done using, for example, an extruder, kneader, or roll in the absence of a solvent, or a reaction vessel with a stirring device in the presence of a solvent.

[0116] A method for uniform mixing involves kneading the mixture using equipment such as a kneader, roll, or planetary mixer at a temperature in the range of 50 to 100°C to obtain a uniform curable resin composition. The obtained curable resin composition can be pulverized and then molded into cylindrical tablets using a molding machine such as a tablet machine, or into granular powder or powdery molded bodies. Alternatively, these compositions can be melted on a surface support and molded into sheets with a thickness of 0.05 mm to 10 mm to obtain molded bodies of curable resin compositions. The obtained molded bodies are non-sticky at 0 to 20°C and maintain almost no decrease in fluidity or curability even when stored at -25 to 0°C for more than a week. The obtained molded bodies can be molded into cured products using a transfer molding machine or a compression molding machine.

[0117] The curable resin composition of the present invention can also be converted into a varnish-like composition (hereinafter simply referred to as varnish) by adding an organic solvent. The curable resin composition of the present invention 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, which can then be 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. The resulting prepreg can then be hot-press molded to obtain a cured product of the curable resin composition of the present invention. In this case, the solvent used is in an amount that accounts for 10 to 70 parts by mass, preferably 15 to 70 parts by mass, of the mixture of the curable resin composition of the present invention and the solvent. If the composition is liquid, a cured product of the curable resin containing carbon fibers can also be obtained directly, for example, by the RTM method.

[0118] Furthermore, the curable resin composition of the present invention can also be used as a modifier for film-type compositions. Specifically, it can be used to improve flexibility and other properties 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 the present invention as a curable resin composition varnish onto a release film, removing the solvent under heating, and then performing B-stage formation. This sheet-like adhesive can be used as an interlayer insulating layer in multilayer substrates and the like.

[0119] The curable resin composition of the present invention can also be heated and melted to reduce viscosity and impregnate reinforcing fibers such as glass fibers, carbon fibers, polyester fibers, polyamide fibers, and alumina fibers to obtain a prepreg. Specific examples include, but are not limited to, 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, as well as inorganic fibers other than glass, and organic fibers such as poly(p-phenylene terephthalamide) (Kevlar®, manufactured by DuPont), fully aromatic polyamide, polyester, poly(p-phenylene benzoxazole), polyimide, and carbon fibers. The shape of the substrate is not particularly limited, but examples include woven fabrics, nonwoven fabrics, rovings, and chopped strand mats. As for the weaving method of the woven fabric, plain weave, twill weave, etc., are known, and these can be appropriately selected and used depending on the intended application and performance. Furthermore, glass woven fabrics that have been opened or surface-treated with silane coupling agents are preferably used. The thickness of the base material is not particularly limited, but is preferably about 0.01 to 0.4 mm. Alternatively, a prepreg can be obtained by impregnating the reinforcing fibers with the varnish and then heating and drying them.

[0120] Furthermore, laminates can also be manufactured using the above-mentioned prepregs. The laminate is not particularly limited as long as it comprises one or more prepregs, and may have any other layers. The method for manufacturing the laminate is not particularly limited and can be any generally known method as appropriate. For example, when forming a metal foil laminate, a multi-stage press, a multi-stage vacuum press, a continuous molding machine, an autoclave molding machine, etc., can be used, and a laminate can be obtained by laminating the above-mentioned prepregs together and then heating and pressing them. At this time, the heating temperature is not particularly limited, but 65 to 300°C is preferred, and 120 to 270°C is more preferred. The pressurizing pressure is not particularly limited, but if the pressurizing pressure is too high it is difficult to adjust the solid content of the resin in the laminate and the quality is not stable, and if the pressurizing pressure is too low it becomes difficult to form air bubbles and the adhesion between layers is poor, so 2.0 to 5.0 MPa is preferred, and 2.5 to 4.0 MPa is more preferred. The laminate of this embodiment can be suitably used as a metal foil laminate described later by comprising a layer made of metal foil. By cutting the above prepreg into the desired shape, laminating it with copper foil or other materials as needed, and then applying pressure to the laminate using methods such as press molding, autoclave molding, or sheet winding molding while heating and curing a curable resin composition, electrical and electronic laminates (printed wiring boards) and carbon fiber reinforced materials can be obtained.

[0121] The curable resin composition of the present invention can also be made into a resin sheet. One method for obtaining a resin sheet from the curable resin composition of the present invention is to apply the curable resin composition onto a support film (support), and then dry it to form a resin composition layer on the support film. When the curable resin composition of the present invention is used to make a resin sheet, it is important that the film softens at the lamination temperature conditions (70°C to 140°C) in the vacuum lamination method and exhibits fluidity (resin flow) that allows for simultaneous lamination of the circuit board and resin filling of via holes or through holes present in the circuit board. It is preferable to blend the components in such a way as to exhibit such characteristics. Furthermore, in order to prevent phenomena such as locally different characteristic values ​​caused by phase separation from occurring in the resulting resin sheet or circuit board (copper-clad laminate, etc.), uniformity of appearance is required to ensure that a certain level of performance is achieved in any desired area.

[0122] 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. It is preferable to be able to fill the holes with resin within this range. When laminating both sides of the circuit board, it is desirable that the through-holes be filled to about half their extent.

[0123] A specific method for manufacturing the aforementioned resin sheet is to prepare a varnished resin composition by incorporating an organic solvent, apply the varnished resin composition to the surface of a support film (Y), and then dry the organic solvent by heating or blowing hot air to form a resin composition layer (X).

[0124] The organic solvents used here preferably include ketones such as acetone, methyl ethyl ketone, and cyclohexanone; acetic acid 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. It is also preferable to use them in a proportion that results in a non-volatile content of 30 to 60% by mass.

[0125] Furthermore, the thickness of the formed resin composition layer (X) must be greater than or equal to the thickness of the conductor layer. Since the thickness of the conductor layer of the circuit board is in the range of 5 to 70 μm, it is preferable that the thickness of the resin composition layer (X) be 10 to 100 μm. In addition, the resin composition layer (X) in the present invention may be protected by a protective film, which will be described later. By protecting it with a protective film, it is possible to prevent dirt and other debris from adhering to the surface of the resin composition layer and to prevent scratches.

[0126] The support film and protective film can be made of polyolefins such as polyethylene, polypropylene, and polyvinyl chloride, polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, polycarbonate, polyimide, and also release paper, copper foil, aluminum foil, and other metal foils. The support film and protective film may be treated with a mat treatment, corona treatment, or release treatment. The thickness of the support film is not particularly limited, but is 10 to 150 μm, preferably in the range of 25 to 50 μm. The thickness of the protective film is preferably 1 to 40 μm.

[0127] The support film (Y) is peeled off after lamination to the circuit board or after an insulating layer has been formed by heat curing. If the support film (Y) is peeled off after the resin composition layer constituting the resin sheet has been heat cured, it is possible to prevent the adhesion of dust and other debris during the curing process. When peeling off after curing, the support film is treated with a release agent beforehand.

[0128] Incidentally, a multilayer printed circuit board can be manufactured from the resin sheet obtained as described above. For example, when the resin composition layer (X) is protected by a protective film, after peeling these, the layer (X) of the resin composition is laminated on one or both sides of the circuit board so as to be directly in contact with the circuit board, for example, by a vacuum lamination method. The lamination method may be a batch type or a continuous roll type. Further, if necessary, the resin sheet and the circuit board may be heated (preheated) as necessary before lamination. As the lamination conditions, it is preferable that the crimping temperature (lamination temperature) is 70 to 140 ° C, and the crimping pressure is 1 to 11 kgf / cm ２ (9.8×10 ４ ~107.9×10 ４ N / m ２ ), and it is preferable to laminate under a reduced pressure of an air pressure of 20 mmHg (26.7 hPa) or less.

[0129] Further, a semiconductor device can be manufactured using the curable resin composition of the present invention. Examples of the semiconductor device include DIP (Dual In-line Package), QFP (Quad Flat Package), BGA (Ball Grid Array), CSP (Chip Size Package), SOP (Small Outline Package), TSOP (Thin Small Outline Package), TQFP (Thin Quad Flat Package), and the like.

[0130] The curable resin composition of the present invention and its cured product can be used in a wide range of fields. Specifically, it can be used for various applications such as molding materials, adhesives, composite materials, paints, and the like. Since the cured product of the curable resin composition described in the present invention exhibits excellent low linear expansion rate and low dielectric characteristics, it is suitable for sealing materials for semiconductor elements, sealing materials for liquid crystal display elements, sealing materials for organic EL elements, laminates (printed wiring boards, substrates for BGA, build-up substrates, etc.), etc., electrical and electronic components, and composite materials for lightweight and high-strength structural materials such as carbon fiber reinforced plastics and glass fiber reinforced plastics, 3D printing, and the like.

[0131] The coefficient of thermal expansion is preferably 80 ppm or less, and more preferably 70 ppm or less. The dielectric loss tangent is preferably 0.003 or less at 10 GHz, and more preferably 0.002 or less. The mechanical strength (maximum point stress) is preferably 30 MPa or more. These measurements are performed by the method described in the examples below.

[0132] The present invention will be specifically described below with reference to examples and comparative examples. In this text, "parts" and "%" refer to "parts by mass" and "mass%", respectively. The softening point and melt viscosity were measured by the following methods: • Softening point: Measured according to the method in accordance with JIS K-7234. • Melt viscosity: Measured using the ICI melt viscosity (150°C) cone plate method, in units of Pa·s.

[0133] GPC (Gel Permeation Chromatography) Analysis Manufacturer: Waters Columns: SHODEX GPC KF-601 (2), KF-602, KF-602.5, KF-603 Flow Rate: 0.5 ml / min. Column Temperature: 40°C Solvent Used: THF (Tetrahydrofuran) Detector: RI (Differential Refraction Detector)

[0134] • HPLC (High-Performance Liquid Chromatography) analysis column: Inertsil ODS-2, flow rate: 1.0 ml / min, column temperature: 40°C, solvents used: acetonitrile / water, detector: photodiode array (225 nm)

[0135] [Synthesis Example 1] Synthesis of Aromatic Amine Resin (A-1) 192 parts aniline, 112 parts toluene, and 100 parts 1,3-bis(2-hydroxy-2-propyl)benzene were charged into a flask equipped with a thermometer, condenser, Dean-Stark azeotropic distillation trap, and stirrer, and 21.5 parts 35% hydrochloric acid was added dropwise over 10 minutes. The system was heated to 160°C, and the reaction was carried out at the same temperature for 17 hours while distilling off water and toluene. After cooling to 80°C, 124 parts toluene was added, and 30 parts 30% sodium hydroxide aqueous solution was added dropwise over 10 minutes. The mixture was then stirred at the same temperature for 2 hours and allowed to stand for 30 minutes. The separated lower aqueous layer was removed, and the reaction solution was washed with water repeatedly until the washing solution was neutral. Then, 158 parts of aromatic amine resin (A-1) represented by formula (2) were obtained by distilling off excess aniline and toluene from the oil layer under reduced pressure using a rotary evaporator. The aromatic amine resin (A-1) had an amine equivalent of 186.1 g / eq. and a softening point of 58.8°C. GPC analysis (RI) revealed that the n=1 compound represented 62.5 area %. The GPC chart is shown in Figure 1.

[0136] [Synthesis Example 2] Synthesis of Maleimide Resin (M-1) A flask equipped with a thermometer, condenser, Dean-Stark azeotropic distillation trap, and stirrer was charged with 73.5 parts maleic anhydride, 126 parts toluene, 1.86 parts methanesulfonic acid, and 12.6 parts N-methyl-2-pyrrolidone, and heated under reflux. Next, a resin solution prepared by dissolving 93 parts aromatic amine resin (A-1) in 55.8 parts toluene was added dropwise over 4 hours while maintaining reflux. During this time, the condensed water and toluene that formed azeotropically under reflux conditions were cooled and separated in the Dean-Stark azeotropic distillation trap. The toluene, which is the organic layer, was returned to the system, and the water was discharged from the system. After the addition of the resin solution dropwise was completed, the reaction was carried out for 10 hours while maintaining reflux and performing dehydration. After the reaction was completed, the mixture was washed with water four times to remove methanesulfonic acid and excess maleic anhydride, and the water was removed from the system by azeotropy of toluene and water under reduced pressure at a temperature below 70°C. Next, 0.93 parts of methanesulfonic acid were added, and the reaction was carried out under reflux for 4 hours. After the reaction was complete, the mixture was washed with water four times until the washing water became neutral. Then, under reduced pressure and heating at 70°C, water was removed from the system by azeotrope of toluene and water. After that, the solvent was removed by distillation under reduced pressure and heating of toluene until the resin concentration was about 70-80%, and then toluene was added to adjust the resin concentration to 60%. This yielded a maleimide solution (V-1) containing the maleimide (M-1) of the present invention. GPC analysis (RI) of the obtained maleimide resin (M-1) showed that the n=1 compound was 57.4 area%, the n=2 compound was 21.3 area%, and the n=3 or more compounds were 21.3 area%. The functional group equivalent was measured by the method described in Japanese Patent Application Publication No. 2020-187012 and was 311 g / eq. The softening point was 118.0°C. The GPC chart is shown in Figure 2.

[0137] [Synthesis Example 3] Synthesis of Styrene Compound (S-1) Tris(2-vinylphenyl)phosphate was synthesized in accordance with the method described in Chinese Patent Application Publication No. 109762115.

[0138] [Example 1, Comparative Examples 1-2] [Preparation of Cured Product] Maleimide resin and styrene compound were measured out in the proportions (parts by mass) shown in Table 1, and acetone was added to make a resin solid content of 70% by mass. The mixture was then mixed to prepare a varnish. The varnish was heated in a vacuum dryer at 60°C for 30 minutes and then at 80°C for 30 minutes to prepare a curable resin composition. The obtained curable resin composition was sandwiched between copper foil and cured under vacuum at a pressure of 1 MPa at 220°C for 2 hours. If a cured product was obtained, it was marked as curable (○); if not, it was marked as curable (×). The results are shown in Table 1.

[0139] The cured material obtained above was subjected to measurement of its cured properties under the following conditions.

[0140] [Flame Retardancy Test] A flame retardancy test was conducted in accordance with the standards of JIS K 6911 5.24.2 Method B. Those conforming to V-0 class were marked with ○, and all others with ×.

[0141] [Measurement of Linear Expansion Coefficient] Manufacturer: TA Instrument Equipment: TMAQ400 Measurement Mode: Tensile heating rate: 2°C / min. Measurement temperature range: 25°C to 330°C After performing the first run at the heating rate and measurement temperature range described above, the sample was cooled to 25°C. Subsequently, the measurement results in the range of 50°C to 300°C during the second run at the same heating rate and measurement temperature range were defined as the linear expansion coefficient.

[0142] [Dielectric Loss Tangent Measurement] Manufacturer: AET Co., Ltd. Equipment: A 10GHz cavity resonator was used. A test specimen measuring 2.5 mm in width and 5 cm in length was dried in a dryer at 120°C for 2 hours before measurement.

[0143] [Mechanical Properties Measurement] Using an AGS-X (manufactured by Shimadzu Corporation), a test specimen with a width of 5 mm, a thickness of 2.5 mm, and a tensile point distance of 5 cm was subjected to a tensile test at 0.5 mm / min, and the maximum point stress was measured.

[0144] In the table, "-" indicates that the measurement was not taken.

[0145] • BMI-70 (manufactured by KI Chemicals Co., Ltd., molecular weight 442, number of functional groups 2, maleimide equivalent 221 g / eq.) • Styrene compound: OPE-1200 (manufactured by Mitsubishi Gas Chemical Company, Inc., Mn 1200)

[0146] The results in Table 1 confirm that Example 1 is superior in all aspects, including curability, flame retardancy, coefficient of thermal expansion, mechanical strength, and dielectric loss tangent.

[0147] The curable resin composition, resin sheet, and cured product of the present invention are suitably used in electrical and electronic components such as semiconductor encapsulants, printed circuit boards, build-up laminates, and optical waveguide devices.

[0148] [Note] As described above, this embodiment includes the following disclosures.

[0149] [1] A curable resin composition containing a maleimide resin represented by the following formula (1) and a styrene compound represented by the following formula (2).

[0150]

[0151] (In formula (1), R １ (where represents a hydrocarbon group with 1 to 20 carbon atoms, and p is an integer from 0 to 4. X represents a hydrocarbon group with 2 to 15 carbon atoms. n is the average number of repetitions, where 1 < n < 5.)

[0152]

[0153] (In formula (2), R ２ (wherein represents a hydrocarbon group having 1 to 20 carbon atoms, and q is an integer from 0 to 4.) [2] The curable resin composition according to item [1] above, wherein the maleimide equivalent of the maleimide resin is 250 to 1000 g / eq. [3] The curable resin composition according to item [1] or [2] above, wherein the maleimide resin is represented by the following formula (3).

[0154]

[0155] (In formula (3), R １ is a hydrocarbon group having 1 to 20 carbon atoms, and p is an integer from 0 to 4. Ar is a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocycle. R is independently a hydrogen atom or a hydrocarbon group having 1 to 5 carbon atoms. n is the average value of the number of repeats, where 1 < n < 5.) [4] The curable resin composition according to the preceding paragraph [3], wherein in formula (3), Ar is one or more of the following formulas (A) to (C).

[0156]

[0157] (In formulas (A) to (C), R ３ ∫ represents a hydrocarbon group having 1 to 10 carbon atoms. a is an integer from 0 to 3. * indicates the bond position.) [5] A curable resin composition according to any one of the preceding paragraphs [1] to [4], further comprising a polymerization initiator. [6] A curable resin composition according to any one of the preceding paragraphs [1] to [5], further comprising a curing accelerator, epoxy resin, active ester compound, phenol resin, polyphenylene ether compound, compound having an ethylenically unsaturated bond, cyanate ester resin, polybutadiene and modified thereof, polystyrene and modified thereof, polyethylene and modified thereof, amine resin, maleimide compound, isocyanate resin, polyamide resin, polyimide resin, and benzoxazine compound. [7] A cured product obtained by curing the curable resin composition according to any one of the preceding paragraphs [1] to [6]. [8] A prepreg in which the curable resin composition according to any one of the preceding paragraphs [1] to [6] is held on a sheet-like fibrous substrate. [9] A cured product obtained by curing the prepreg described in item [8] above.

Claims

1. A curable resin composition containing a maleimide resin represented by the following formula (1) and a styrene compound represented by the following formula (2). (In formula (1), R １ (where represents a hydrocarbon group with 1 to 20 carbon atoms, and p is an integer from 0 to 4. X represents a hydrocarbon group with 2 to 15 carbon atoms. n is the average number of repetitions, where 1 < n < 5.) (In formula (2), R ２ (where 'q' represents a hydrocarbon group with 1 to 20 carbon atoms, and 'q' is an integer from 0 to 4.) 2. The curable resin composition according to claim 1, wherein the maleimide equivalent of the maleimide resin is 250 to 1000 g / eq.

3. The curable resin composition according to claim 1, wherein the maleimide resin is represented by the following formula (3). (In formula (3), R １ represents a hydrocarbon group with 1 to 20 carbon atoms, and p is an integer from 0 to 4. Ar represents a substituted or unsubstituted aromatic hydrocarbon ring, or a substituted or unsubstituted aromatic heterocycle. R independently represents a hydrogen atom or a hydrocarbon group with 1 to 5 carbon atoms. n is the average number of repeats, where 1 < n < 5.

4. The curable resin composition according to claim 3, wherein in formula (3), Ar is one or more of the following formulas (A) to (C). (In formulas (A) to (C), R ３ represents a hydrocarbon group with 1 to 10 carbon atoms. a is an integer from 0 to 3. * indicates the bond position.

5. The curable resin composition according to claim 1, further containing a polymerization initiator.

6. The curable resin composition according to claim 1, further comprising at least one selected from a curing accelerator, epoxy resin, active ester compound, phenol resin, polyphenylene ether compound, compound having an ethylenically unsaturated bond, cyanate ester resin, polybutadiene and modified thereof, polystyrene and modified thereof, polyethylene and modified thereof, amine resin, maleimide compound, isocyanate resin, polyamide resin, polyimide resin, and benzoxazine compound.

7. A cured product obtained by curing the curable resin composition according to any one of claims 1 to 6.

8. A prepreg comprising a curable resin composition according to any one of claims 1 to 6, held on a sheet-like fibrous substrate.

9. A cured product obtained by curing the prepreg described in claim 8.

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