WO2024203145A1 - Curable resin composition and cured product thereof - Google Patents

Abstract

The present invention provides: a curable resin composition having a high degree of biomass and having excellent high heat resistance, low dielectric properties, and mechanical properties; and a cured product of the curable resin composition.　The curable resin composition comprises an epoxy resin represented by formula (1) and a phenol resin represented by formula (2). (In formula (1), n is the average number of repeating units, and represents a real number within the range 1<n<15.) (In formula (2), n is the average number of repeating units, and represents a real number within the range 1<n<15.)

Description

Curable resin composition and cured product thereof

The present invention relates to a curable resin composition containing a specific epoxy resin and a specific phenolic resin, and a cured product thereof, which is suitable for use in sealing materials for semiconductor elements, electrical and electronic components such as printed wiring boards and build-up laminates, lightweight, high-strength materials such as carbon fiber reinforced plastics and glass fiber reinforced plastics, 3D printing applications, and in the field of adhesives.

Epoxy resins are widely used in fields such as electrical and electronic parts, structural materials, adhesives, and paints due to their workability and the excellent electrical properties, heat resistance, adhesiveness, and moisture resistance (water resistance) of the cured products. In recent years, with the development of the electrical and electronic fields in particular, there has been a demand for further improvements in the properties of resins, such as heat resistance, low dielectric constant, and low dielectric tangent. In addition, as structural materials, there is a demand for lightweight materials with excellent mechanical properties for aerospace materials and leisure and sports equipment applications.

In recent years, biomass resources have been attracting attention as a carbon-neutral resource from the perspective of environmental issues. Furfural is known as a compound derived from biomass, and Patent Document 1 discloses an epoxy resin that uses furfural as a raw material.

JP 2007-211254 A

However, in Patent Document 1, the epoxy resin composition is made by mixing an epoxy resin made from furfural as a raw material with a phenol novolac resin, which is a petrochemical-derived hardener, so the biomass content of the composition is low.

　Generally, when trying to increase the biomass content, it becomes difficult to maintain the performance required of the curable resin composition, so there has been a demand for a curable resin composition that has a high biomass content while still satisfying the required properties.

The present invention was made in consideration of the above situation, and aims to provide a curable resin composition with a high biomass content, high heat resistance, low dielectric properties, and excellent mechanical properties, as well as a cured product thereof.

That is, the present invention relates to the following [1] to [8]. Note that in the present invention, "(Numerical value 1) to (Numerical value 2)" indicates that the upper and lower limits are included.
[1]
A curable resin composition comprising an epoxy resin represented by the following formula (1) and a phenol resin represented by the following formula (2):

(In formula (1), n is the average number of repetitions and is a real number between 1 and 15.)

(In formula (2), n is the average number of repetitions and is a real number in the range of 1<n<15.)
[2]
The curable resin composition according to the above item [1], wherein the phenol resin has a biomass degree of 20% or more.
[3]
The curable resin composition according to the above item [1] or [2], wherein the epoxy resin has an ICI viscosity (150°C) of 0.01 to 0.20 Pa·s.
[4]
The curable resin composition according to any one of the above items [1] to [3], having a biomass ratio of 20% or more.
[5]
The curable resin composition according to any one of the above items [1] to [4], which is for carbon fiber reinforced plastics.
[6]
The curable resin composition according to any one of the above items [1] to [4], which is used for a semiconductor element encapsulation material.
[7]
The curable resin composition according to any one of the above items [1] to [4], which is for use in a printed wiring board.
[8]
A cured product obtained by curing the curable resin composition according to any one of the above items [1] to [7].

The present invention relates to a curable resin composition that has a high biomass content and has high heat resistance, low dielectric properties, and excellent mechanical properties. Therefore, the present invention is useful for insulating materials for electric and electronic components (highly reliable semiconductor encapsulation materials, etc.), laminates (printed wiring boards, build-up boards, etc.), various composite materials including CFRP, adhesives, etc.

1 shows a GPC chart of Synthesis Example 1. 2 shows a GPC chart of Synthesis Example 2.

The curable resin composition of this embodiment contains an epoxy resin represented by the following formula (1) and a phenolic resin represented by the following formula (2).

(In formula (1), n is the average number of repetitions and is a real number between 1 and 15.)

(In formula (2), n is the average number of repetitions and is a real number in the range 1<n<15.)

In the above formulas (1) and (2), the value of n can be calculated from the number average molecular weight determined by measuring the epoxy resin by gel permeation chromatography (GPC, detector: RI) or from the area ratio of each of the separated peaks. n is preferably a real number in the range of 1<n<15, more preferably 1<n<10, and particularly preferably 1<n<5.

The phenolic resin represented by the formula (2) can also be used as a raw material for the epoxy resin represented by the formula (1). In other words, the epoxy resin represented by the formula (1) can be obtained by reacting the phenolic resin represented by the formula (2) with epihalohydrin.

The epihalohydrin is readily available on the market. The amount of epihalohydrin used is preferably 2.0 to 10 moles per mole of hydroxyl groups in the raw phenol mixture, more preferably 3.0 to 8.0 moles, and even more preferably 3.5 to 6.0 moles.

In the above reaction, an alkali metal hydroxide can be used as a catalyst for promoting the epoxidation step. Examples of alkali metal hydroxides that can be used include sodium hydroxide, potassium hydroxide, etc., and a solid or an aqueous solution thereof can be used. In this embodiment, however, it is particularly preferable to use a solid formed into a flake shape in terms of solubility and handling.
The amount of the alkali metal hydroxide used is preferably 0.90 to 1.5 mol, more preferably 0.95 to 1.25 mol, and even more preferably 0.99 to 1.15 mol, per mol of hydroxyl groups in the raw phenol mixture.

Furthermore, to accelerate the reaction, a quaternary ammonium salt such as tetramethylammonium chloride, tetramethylammonium bromide, or trimethylbenzylammonium chloride may be added as a catalyst. The amount of quaternary ammonium salt used is preferably 0.1 to 15 g, more preferably 0.2 to 10 g, per mole of hydroxyl groups in the raw phenol mixture.

The reaction temperature is preferably 30 to 90° C., more preferably 35 to 80° C. In particular, in this embodiment, for higher purity epoxidation, the reaction temperature is preferably 50° C. or higher, and particularly preferably 60° C. or higher. The reaction time is preferably 0.5 to 10 hours, more preferably 1 to 8 hours, and particularly preferably 1 to 3 hours. If the reaction time is short, the reaction does not proceed to completion, and if the reaction time is long, by-products are produced, which are not preferred.
The reaction product of these epoxidation reactions is washed with water or heated under reduced pressure to remove epihalohydrin and solvent. Furthermore, in order to obtain an epoxy resin with a small amount of hydrolyzable halogen, the recovered epoxy resin can be dissolved in a ketone compound having 4 to 7 carbon atoms (e.g., methyl isobutyl ketone, methyl ethyl ketone, cyclopentanone, cyclohexanone, etc.) as a solvent, and an aqueous solution of an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide is added to carry out the reaction to ensure ring closure. In this case, the amount of the alkali metal hydroxide used is preferably 0.01 to 0.3 mol, more preferably 0.05 to 0.2 mol, per mol of hydroxyl groups in the raw material phenol mixture used in the epoxidation. The reaction temperature is preferably 50 to 120° C., and the reaction time is preferably 0.5 to 2 hours.

After the reaction is complete, the salt formed is removed by filtration, washing with water, etc., and the solvent is then distilled off under heating and reduced pressure to obtain the epoxy resin represented by formula (1).

In the synthesis method of the phenolic resin represented by formula (2), when furfural is reacted (condensed) with a phenol, the amount of the phenol is preferably 1.5 to 20 moles, and more preferably 3 to 10 moles, per mole of furfural.

Phenols include catechol, resorcinol, and hydroquinone as disubstituted phenols, and phenol as monosubstituted phenols, and may be used alone or in combination of two or more types.

Solvents include, but are not limited to, methanol, ethanol, propanol, isopropanol, toluene, xylene, etc., and may be used alone or in combination of two or more. When using a solvent, the amount used is preferably 5 to 500 parts by weight, more preferably 10 to 300 parts by weight, per 100 parts by weight of phenol.

In the above condensation reaction, it is preferable to use a base catalyst. Polycondensation is possible with an acid catalyst, but reactions between furfurals occur, resulting in a large amount of by-products. There is also a method using an organometallic compound, but this is cost-inefficient. Specific examples of base catalysts include alkali metal hydroxides such as lithium hydroxide, sodium hydroxide, and potassium hydroxide, alkaline earth metal hydroxides such as magnesium hydroxide and calcium hydroxide, alkali metal alkoxides such as sodium methoxide, sodium ethoxide, potassium methoxide, potassium ethoxide, and potassium tert-butoxide, and alkaline earth metal alkoxides such as magnesium methoxide and magnesium ethoxide, but the invention is not limited to these, and the catalyst may be used alone or in combination of two or more kinds. The amount of catalyst used is preferably 0.005 to 2.0 times the moles of phenol, and more preferably 0.01 to 1.1 times the moles.

The condensation reaction in the presence of these base catalysts is preferably carried out in the range of 40 to 180°C, particularly preferably in the range of 80 to 165°C, and the reaction time is preferably selected in the range of 0.5 to 10 hours. The reaction product thus obtained is neutralized so that the system becomes neutral, or repeatedly washed with water in the presence of a solvent, and the water is separated and drained, and the solvent and unreacted materials are removed under heating and reduced pressure to obtain the phenolic resin represented by formula (2).

The phenolic resin represented by formula (2) is preferably present in an amount of 0.7 to 1.2 equivalents per equivalent of epoxy group in the epoxy resin represented by formula (1). If the amount is less than 0.7 equivalents per equivalent of epoxy group, or if the amount exceeds 1.2 equivalents, curing may be incomplete and good cured physical properties may not be obtained.

From the viewpoint of environmental issues, the biomass degree of the epoxy resin represented by the formula (1) is preferably 20% or more, and more preferably 25% or more. The biomass degree of the phenol resin represented by the formula (2) is preferably 20% or more, and more preferably 30% or more. The biomass degree of the curable resin composition of this embodiment is preferably 20% or more, and more preferably 25% or more. There is no particular limit to the upper limit of the biomass degree, and it may be 100%, but in consideration of the cured physical properties, it is preferably 60% and more preferably 40%. A high biomass degree can also reduce the amount of fossil resource-based materials such as petroleum used, and is therefore meaningful in terms of sustainable use of resources.

The biomass content of each material and curable resin composition can be determined by accelerator gravimetric analysis in accordance with ASTM D6866-21.

In the curable resin composition of this embodiment, the epoxy resin represented by formula (1) may be used alone or in combination with other epoxy resins. When used in combination, the proportion of the epoxy resin represented by formula (1) in the total epoxy resin is preferably 5 to 95% by weight, more preferably 10 to 95% by weight, and even more preferably 15 to 95% by weight. If the amount added is small, sufficient heat resistance may not be achieved.

Specific examples of epoxy resins that can be used in combination with the epoxy resin represented by formula (1) include polycondensates of bisphenols (bisphenol A, bisphenol F, bisphenol S, biphenol, bisphenol AD, etc.) or phenols (phenol, alkyl-substituted phenol, aromatic-substituted phenol, naphthol, alkyl-substituted naphthol, dihydroxybenzene, alkyl-substituted dihydroxybenzene, dihydroxynaphthalene, etc.) with various aldehydes (formaldehyde, acetaldehyde, alkyl aldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, etc.); polycondensates of the phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzaldehyde, etc.); polycondensates of the phenols and aromatic dimethanols (benzene dimethanol, biphenyl dimethanol, etc.); polycondensates of the phenols and aromatic dichloromethyls (α,α'-dichloroxylene, bischloromethylbiphenyl, etc.); polycondensates of the phenols and aromatic bisalkoxymethyls (bismethoxymethylbenzene, bismethoxymethylbiphenyl, bisphenoxymethylbiphenyl, etc.); polycondensates of the bisphenols and various aldehydes or alcohols, etc., glycidyl ether epoxy resins, alicyclic epoxy resins, glycidylamine epoxy resins, glycidyl ester epoxy resins, etc. Specific examples of epoxy resins containing plant-derived components include compounds obtained by epoxidizing polycondensates obtained by polycondensing various aldehydes with cardanol derived from cashew oil as the phenol, and compounds obtained by epoxidizing linseed oil or soybean oil. There is no limitation to these, as long as they are commonly used epoxy resins. These may be used alone or in combination with two or more kinds. In particular, it is preferable to use them in combination with epoxy resins containing plant-derived components, as this can increase the biomass ratio.

The curable resin composition of this embodiment may be used in combination with a curing agent other than the phenolic resin represented by formula (2). Examples include acid anhydride compounds, amine compounds, amide compounds, phenolic compounds, and active ester compounds. Specific examples of curing agents that can be used in combination include acid anhydride compounds such as phthalic anhydride, trimellitic anhydride, pyromellitic anhydride, maleic anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride, methylnadic anhydride, hexahydrophthalic anhydride, and methylhexahydrophthalic anhydride; amide compounds such as dicyandiamide, polyamide resins synthesized from a dimer of linoleic acid and ethylenediamine; o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diamidinosylamine, and the like. aminodiphenyl sulfone, 3,4'-diaminodiphenyl sulfone, 3,3'-diaminodiphenyl sulfone, 2,2'-diaminodiphenyl sulfone, diethyltoluenediamine, dimethylthiotoluenediamine, diaminodiphenylmethane, 3,3'-dimethyl-4,4'-diaminodiphenylmethane, 3,3'-diethyl-4,4'-diaminodiphenylmethane, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3',5,5'-tetramethyl ethyldiphenylmethane, 4,4'-diamino-3,3',5,5'-tetraethyldiphenylmethane, 4,4'-diamino-3,3',5,5'-tetraisopropyldiphenylmethane, 4,4'-methylenebis(N-methylaniline), bis(aminophenyl)fluorene, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether, 2,2'-bis[4-(4-aminophenoxy)phenyl]propane, bis[4-(4-aminophenoxy)phenyl]sulfone, 1,3'-bis Aromatic amine compounds such as (4-aminophenoxy)benzene, 1,4'-bis(4-aminophenoxy)benzene, 1,4'-bis(4-aminophenoxy)biphenyl, 4,4'-(1,3-phenylenediisopropylidene)bisaniline, 4,4'-(1,4-phenylenediisopropylidene)bisaniline, naphthalenediamine, benzidine, and dimethylbenzidine; 1,3-bis(aminomethyl)cyclohexane, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), norborna aliphatic amine compounds such as diamine, ethylenediamine, propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, dimer diamine, and triethylenetetramine; bisphenols (bisphenol A, bisphenol F, bisphenol S, biphenol, bisphenol AD, and the like) or phenols (phenol, alkyl-substituted phenols, aromatic substituted phenols, naphthol, alkyl-substituted naphthol, dihydroxybenzene, alkyl-substituted dihydroxybenzene, and the like); polycondensates of phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, etc.) with various aldehydes (formaldehyde, acetaldehyde, alkyl aldehydes, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, etc.); phenolic compounds such as polymers of the phenols and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, etc.), polycondensates of the phenols and aromatic dimethanols (benzene dimethanol, biphenyl dimethanol, etc.), polycondensates of the phenols and aromatic dichloromethyls (α,α'-dichloroxylene, bischloromethylbiphenyl, etc.), polycondensates of the phenols and aromatic bisalkoxymethyls (bismethoxymethylbenzene, bismethoxymethylbiphenyl, bisphenoxymethylbiphenyl, etc.), polycondensates of the bisphenols and various aldehydes, and modified products thereof; active ester compounds such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds; and the like, but are not limited to these.

The curable resin composition of this embodiment may be used in combination with a curing accelerator. Examples of the curing accelerator that can be used include imidazoles such as 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, and 2-ethyl-4-methylimidazole; tertiary amines such as 2-(dimethylaminomethyl)phenol, triethylenediamine, triethanolamine, and 1,8-diazabicyclo[5,4,0]undecene-7; organic phosphines such as triphenylphosphine, diphenylphosphine, and tributylphosphine; metal compounds such as tin octylate; tetra-substituted phosphonium tetra-substituted borates such as tetraphenylphosphonium tetraphenylborate and tetraphenylphosphonium ethyltriphenylborate; tetraphenylboron salts such as 2-ethyl-4-methylimidazole tetraphenylborate and N-methylmorpholine tetraphenylborate; and carboxylic acid compounds such as benzoic acid, phthalic acid, isophthalic acid, terephthalic acid, naphthoic acid, and salicylic acid. The curing accelerator is used as needed in an amount of 0.01 to 15 parts by weight per 100 parts by weight of epoxy resin.

The curable resin composition of this embodiment may contain an inorganic filler as needed. Examples of inorganic fillers include, but are not limited to, powders such as crystalline silica, fused silica, alumina, zircon, calcium silicate, calcium carbonate, silicon carbide, silicon nitride, boron nitride, zirconia, fosterite, steatite, spinel, titania, and talc, or beads obtained by shaping these into spherical form. These may be used alone or in combination of two or more. The amount of these inorganic fillers used varies depending on the application, but when used as an encapsulant for semiconductor elements, it is preferable to use the inorganic fillers in a proportion of 20% by weight or more in the curable resin composition in terms of the heat resistance, moisture resistance, mechanical properties, and flame retardancy of the cured product of the curable resin composition, more preferably 30% by weight or more, and more preferably 70 to 95% by weight in order to improve the linear expansion coefficient with the lead frame.

The curable resin composition of this embodiment can be blended with a release agent to improve release from the mold during molding. Any of the conventionally known release agents can be used, including, for example, ester waxes such as carnauba wax and montan wax, fatty acids such as stearic acid and palmitic acid and their metal salts, and polyolefin waxes such as oxidized polyethylene and non-oxidized polyethylene. These may be used alone or in combination of two or more. The amount of these release agents blended is preferably 0.5 to 3% by weight of the total organic components. If it is less than this, release from the mold is poor, and if it is too much, adhesion to the lead frame and the like is poor.

The curable resin composition of this embodiment can be blended with a coupling agent to improve adhesion between the inorganic filler and the resin component. Any of the conventionally known coupling agents can be used, including, for example, various alkoxysilane compounds such as vinylalkoxysilane, epoxyalkoxysilane, styrylalkoxysilane, methacryloxyalkoxysilane, acryloxyalkoxysilane, aminoalkoxysilane, mercaptoalkoxysilane, and isocyanatoalkoxysilane, alkoxytitanium compounds, and aluminum chelates. These may be used alone or in combination of two or more. The coupling agent may be added by treating the surface of the inorganic filler with the coupling agent beforehand and then kneading it with the resin, or by mixing the coupling agent with the resin and then kneading the inorganic filler.

　The curable resin composition of this embodiment may contain known additives as necessary. Specific examples of additives that may be used include polybutadiene and modified products thereof, modified acrylonitrile copolymers, polyphenylene ether, polystyrene, polyethylene, polyimide, fluororesin, maleimide-based compounds, cyanate ester-based compounds, silicone gel, silicone oil, and colorants such as carbon black, phthalocyanine blue, and phthalocyanine green.

The curable resin composition of this embodiment is obtained by uniformly mixing the above components. There are no particular limitations on the method for producing the curable resin composition of this embodiment, but it can be obtained, for example, by thoroughly mixing the epoxy resin with a curing agent, a curing accelerator, an inorganic filler, a release agent, a silane coupling agent, additives, etc., using an extruder, kneader, roll, planetary mixer, etc. until the mixture is uniform.

The obtained curable resin composition can be formed into various forms such as a resin sheet or a prepreg, depending on the molding method. A prepreg form can be obtained, for example, by heating and melting the curable resin composition and/or the resin sheet of this embodiment to reduce the viscosity and impregnating the composition into a fiber substrate.

The curable resin composition of this embodiment can be dissolved in a solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, dimethylacetamide, or N-methylpyrrolidone as necessary to form a varnish-like composition (hereinafter simply referred to as varnish), which can then be impregnated into a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, or paper, and dried by heating to produce a prepreg. The solvent used in this case is in an amount that occupies 10 to 70% by weight, preferably 15 to 70% by weight, of the mixture of the curable resin composition of this embodiment and the solvent.

The above prepregs are cut into the desired shape and laminated, and then the laminate is subjected to pressure using a press molding method, autoclave molding method, sheet winding molding method, or other method while the epoxy resin composition is heated and cured to obtain carbon fiber reinforced plastic (CFRP). Copper foil or organic film can also be laminated when laminating the prepregs.

In addition to the above-mentioned methods, CFRP can also be obtained by molding using known methods. For example, resin transfer molding technology (RTM method) can be used, in which a carbon fiber substrate (usually woven carbon fiber fabric) is cut, laminated, and shaped to create a preform (a preliminary molded body before being impregnated with resin), the preform is placed in a mold and the mold is closed, resin is injected to impregnate the preform and harden it, and the mold is then opened to remove the molded product. In addition, it is also possible to use a type of RTM method, such as the VaRTM method, the SCRIMP (Seeman's Composite Resin Infusion Molding Process) method, or the CAPRI (Controlled Atmospheric Pressure Resin Infusion) method, which more appropriately controls the resin injection process, particularly the VaRTM method, by evacuating the resin supply tank described in JP-A-2005-527410 to a pressure lower than atmospheric pressure, using circulatory compression, and controlling the net molding pressure. In addition, other methods that can be used include the film stacking method, in which the fiber substrate is sandwiched between resin sheets (films), the method of attaching powdered resin to the reinforced fiber substrate to improve impregnation, the molding method (Powder Impregnated Yarn) that uses a fluidized bed or fluid slurry method in the process of mixing the resin into the fiber substrate, and the method of blending resin fibers into the fiber substrate.

Carbon fibers include acrylic, pitch, and rayon carbon fibers, with acrylic carbon fibers being preferred due to their high tensile strength. The carbon fibers can be in the form of twisted yarn, untwisted yarn, or non-twisted yarn, but untwisted yarn or non-twisted yarn is preferred due to the good balance between the formability and strength properties of the fiber-reinforced composite material.

The cured product of the curable resin composition of this embodiment can be used for various applications other than the above-mentioned applications such as CFRP, such as adhesives, paints, coating agents, molding materials (including sheets, films, CFRP, etc.), encapsulants for semiconductor elements, encapsulants for liquid crystal display elements, encapsulants for organic EL elements, printed wiring boards (BGA substrates, build-up substrates, etc.), and other electric and electronic parts, 3D printing, as well as additives for other resins, etc.

The adhesives include adhesives for civil engineering, construction, automotive, general office, and medical use, as well as adhesives for electronic materials. Among these, adhesives for electronic materials include interlayer adhesives for multilayer boards such as build-up boards, die bonding agents, semiconductor adhesives such as underfills, underfills for reinforcing BGAs, and mounting adhesives such as anisotropic conductive films (ACFs) and anisotropic conductive pastes (ACPs), and can be used for a variety of purposes.

When the curable resin composition of this embodiment is applied to an encapsulant for semiconductor elements, the curable resin composition of this embodiment is placed in a mold along with a lead frame equipped with a semiconductor element and a semiconductor package substrate, and molded by melt casting, transfer molding, injection molding, compression molding, or the like, and then heated at 80 to 200°C for 2 to 10 hours to obtain a cured product. Examples of semiconductor devices manufactured using this encapsulant include potting, dipping, and transfer mold encapsulation for capacitors, transistors, diodes, light-emitting diodes, ICs, and LSIs, potting encapsulation for COB, COF, TAB, and the like for ICs and LSIs, underfill for flip chips, and encapsulation (including reinforcing underfill) when mounting IC packages such as QFP, BGA, and CSP.

When the curable resin composition of this embodiment is applied to a printed wiring board application, a prepreg can be obtained by heating and melting the composition to reduce the viscosity and impregnating the composition into reinforcing fibers such as glass fibers and polyamide fibers. Specific examples of the composition 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, and/or organic fibers. The shape of the substrate is not particularly limited, but examples include woven fabric, nonwoven fabric, roving, chopped strand mat, and the like. In addition, the weaving method of the woven fabric includes plain weave, saddle weave, twill weave, and the like, and these known methods can be appropriately selected and used depending on the intended application and performance. In addition, woven fabrics that have been opened and glass woven fabrics that have been surface-treated with a silane coupling agent are preferably used. The thickness of the substrate is not particularly limited, but is preferably about 0.01 to 0.4 mm. In addition, the varnish can be impregnated into reinforcing fibers and dried by heating to obtain a prepreg, which can then be used to create a copper clad laminate (CCL). The obtained prepreg and CCL can be hot-press molded to create a laminate using the curable resin composition of this embodiment. The laminate is not particularly limited as long as it has one or more prepregs, and may have any other layers. In addition, a sheet-like adhesive can be obtained by applying the varnish onto a release film, removing the solvent under heating, and performing B-stage formation. This sheet-like adhesive can be used as an interlayer insulating layer in a multilayer board or an adhesive sheet when mounting a semiconductor. The curable resin composition of this embodiment can also be used suitably for special board materials such as package boards (substrates) and HDIs (high density interconnects).

The present invention will be explained in more detail below with reference to synthesis examples and working examples. The materials, processing contents, processing procedures, etc. shown below can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be interpreted as being limited by the specific examples shown below. Hereinafter, parts are parts by weight unless otherwise specified.

Various analytical methods were carried out under the following conditions.
Epoxy equivalent: Measured by the method described in JIS K-7236, and the unit is g/eq.
Softening point: Measured according to a method in accordance with JIS K-7234, and the unit is °C.
Melt Viscosity: ICI melt viscosity (150° C.) was measured by the cone-plate method, and the unit is Pa·s.
-Biomass content analysis (accelerator gravimetric analysis)
The measurement was carried out in accordance with ASTM D6866-21 and the calculation was carried out in units of %.

[Synthesis Example 1]
In a flask equipped with a stirrer, a reflux condenser, and a stirrer, 254 parts by weight of phenol, 63 parts by weight of water, and 27 parts by weight of sodium hydroxide were charged, stirred, dissolved, and then heated to 110°C, where 44 parts by weight of furfural was dropped over 2 hours. After that, the mixture was reacted at 110°C for 3 hours, and then heated to 145°C. During the temperature increase, the water distilled out was removed from the system. After reaching 145°C, the mixture was reacted for 4 hours. Then, the mixture was cooled to 80°C, 63 parts by weight of water was charged, and 4 parts by weight of phosphoric acid and 63 parts by weight of 35% hydrochloric acid were added to neutralize. After repeated washing with water, unreacted phenol was distilled off under reduced pressure by heating to obtain 109 parts by weight of phenolic resin A represented by the formula (2). From GPC, the average value n of the number of repetitions was 1.5, and the biomass degree was 34%. The GPC chart of phenolic resin A is shown in Figure 1.

[Synthesis Example 2]
78 parts by weight of phenolic resin A obtained in Synthesis Example 1 was charged into a reaction vessel with 254 parts by weight of epichlorohydrin (ECH, hereinafter the same), 64 parts by weight of dimethyl sulfoxide (DMSO, hereinafter the same), and 13 parts by weight of water, and after heating, stirring, and dissolving, 23 parts by weight of flake-shaped sodium hydroxide was charged in portions over 2 hours while maintaining the temperature at 45°C. Thereafter, the reaction was further carried out at 45°C for 2 hours and at 70°C for 60 minutes. Next, washing with water was repeated to remove by-product salts and dimethyl sulfoxide, and then excess epichlorohydrin was distilled off from the oil layer under heating and reduced pressure, and 218 parts by weight of methyl isobutyl ketone was added to the residue and dissolved. This methyl isobutyl ketone solution was heated to 70°C, 7 parts by weight of 30% aqueous sodium hydroxide solution was added, and the reaction was carried out for 1 hour, after which the reaction solution was repeatedly washed with water until the washing liquid became neutral. Next, methyl isobutyl ketone was distilled off from the oil layer under heating and reduced pressure to obtain 97 parts by weight of epoxy resin A represented by the above formula (1). The epoxy equivalent was 214 g/eq., the softening point was 49°C, the ICI melt viscosity was 0.04 Pa s, the average number of repeats n was 2.1 from GPC, and the biomass degree was 25%. The GPC chart of epoxy resin A is shown in Figure 2.

[Example 1]
The epoxy resin A obtained in Synthesis Example 2 was used as the base resin, the phenol resin A obtained in Synthesis Example 1 was used as the curing agent, and TPP (triphenylphosphine) was used as the curing accelerator. These were mixed and kneaded in the weight ratio shown in the composition in Table 1, and cured at 180°C for 6 hours to produce a cured product. The biomass content of the cured product was 28.3%.

[Comparative Example 1]
The epoxy resin A obtained in Synthesis Example 1 was used as the base resin, PN (phenol novolac resin, manufactured by Meiwa Chemical Industry Co., Ltd., hydroxyl equivalent 103 g/eq.) as a curing agent, and TPP (triphenylphosphine) as a curing accelerator were mixed and kneaded in the weight ratio shown in the composition in Table 1, and cured at 180°C for 6 hours to produce a cured product. The biomass degree of the cured product was 16.6%.

The physical properties were measured under the following conditions.
<Heat resistance (Tg) measurement conditions>
Dynamic viscoelasticity measuring instrument: TA-instruments, DMA-Q800
Measurement temperature range: 25 to 300°C
Temperature rise rate: 2° C./min. Tg: The peak point of Tan δ was taken as Tg.
<Dielectric constant and dielectric tangent test>
The test was performed by a cavity resonator perturbation method at 25° C. using a 10 GHz cavity resonator manufactured by AET Co., Ltd. The sample size was 2.5 mm wide x 50 mm long, and the thickness was 0.3 mm.
<Tensile modulus, maximum tensile stress>
Using an Autograph AGS-X manufactured by Shimadzu Corporation, the test pieces were clamped so that they had a length of 5 cm and were tensile measured in the 180° direction at the above test speed with a tensile speed of 0.5 mm/min.

The results in Table 1 confirm that Example 1 has a high biomass content, high heat resistance, low dielectric properties, and excellent mechanical properties.

Claims (8)

A curable resin composition comprising an epoxy resin represented by the following formula (1) and a phenol resin represented by the following formula (2):
(In formula (1), n is the average number of repetitions and is a real number in the range of 1<n<15.)
(In formula (2), n is the average number of repetitions and is a real number in the range of 1<n<15.) The curable resin composition according to claim 1, wherein the biomass content of the phenolic resin is 20% or more. The curable resin composition according to claim 1, wherein the epoxy resin has an ICI viscosity (150°C) of 0.01 to 0.20 Pa·s. The curable resin composition according to claim 1, having a biomass ratio of 20% or more. The curable resin composition according to any one of claims 1 to 4, which is for use in carbon fiber reinforced plastics. The curable resin composition according to any one of claims 1 to 4, which is used as an encapsulant for semiconductor elements. The curable resin composition according to any one of claims 1 to 4, which is for use in a printed wiring board. A cured product obtained by curing the curable resin composition according to claim 1 .

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