Curable resin composition and cured product thereof

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 has an epoxy resin represented by formula (1) and a lignin-modified phenol resin or a cashew-modified phenol resin. (In formula (1), n is the average number of repetitions and denotes a real number within the range 1<n<15.)

Description

Curable resin composition and cured product thereof

[0001] The present invention relates to a curable resin composition containing a specific epoxy resin and a lignin-modified phenolic resin or a cashew-modified phenolic resin, and a cured product thereof, which is suitable for use in electrical and electronic components such as encapsulants for semiconductor elements, 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 adhesives.

[0002] Epoxy resins are widely used in fields such as electrical and electronic components, structural materials, adhesives, and paints due to their workability and the excellent electrical properties, heat resistance, adhesiveness, and moisture resistance (water resistance) of their 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 resin properties such as heat resistance, low dielectric constant, and low dielectric loss tangent. Furthermore, as structural materials, lightweight materials with excellent mechanical properties are required for aerospace applications and leisure and sports equipment applications.

[0003] In recent years, biomass resources have been attracting attention as a carbon-neutral resource from the viewpoint of environmental issues. Furfural is known as a compound derived from biomass, and Patent Document 1 discloses an epoxy resin using furfural as a raw material.

[0004] Japanese Patent Application Laid-Open No. 2007-211254

[0005] However, in Patent Document 1, an epoxy resin composition is prepared by mixing an epoxy resin using furfural as a raw material with a phenol novolac resin, which is a petrochemical-derived curing agent, and therefore the biomass content of the composition is low.

[0006] Generally, when an attempt is made to increase the biomass degree, it becomes difficult to maintain the performance required of the curable resin composition. Therefore, there has been a demand for a curable resin composition that has a high biomass degree while satisfying the required properties.

[0007] The present invention has been made in view of the above circumstances, and aims to provide a curable resin composition having a high biomass content and excellent heat resistance, low dielectric properties, and mechanical properties, and a cured product thereof.

[0008] That is, the present invention relates to the following [1] to [9]. In the present invention, "(Numerical value 1) to (Numerical value 2)" indicates that the upper and lower limits are included. [1] A curable resin composition containing an epoxy resin represented by the following formula (1) and a lignin-modified phenolic resin or a cashew-modified phenolic resin:

[0009]

[0010] (In formula (1), n ​​is the average value of the number of repetitions and is a real number satisfying the condition 1<n<15.) [2] The curable resin composition according to the preceding item [1], wherein the lignin-modified phenolic resin or the cashew-modified phenolic resin has a biomass degree of 20% or more. [3] The curable resin composition according to the preceding 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 preceding items [1] to [3], wherein the biomass degree is 20% or more. [5] The curable resin composition according to any one of the preceding items [1] to [4], wherein the curable resin composition is for use in carbon fiber reinforced plastics. [6] The curable resin composition according to any one of the preceding items [1] to [4], wherein the curable resin composition is for use in a semiconductor element encapsulation material. [7] The curable resin composition according to any one of the preceding items [1] to [4], wherein the curable resin composition 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 preceding items [1] to [7].

[0011] The present invention relates to a curable resin composition having a high biomass content and exhibiting high heat resistance, low dielectric properties, and excellent mechanical properties. Therefore, the present invention is useful for insulating materials for electric and electronic components (e.g., highly reliable semiconductor encapsulation materials), laminates (e.g., printed wiring boards and build-up boards), various composite materials including CFRP, adhesives, and the like.

[0012] 1 shows a GPC chart of Synthesis Example 1. FIG. 2 shows a GPC chart of the lignin-modified phenolic resin used in Example 1.

[0013] The curable resin composition of the present embodiment contains an epoxy resin represented by the following formula (1) and a lignin-modified phenolic resin or a cashew-modified phenolic resin.

[0014]

[0015] (In formula (1), n ​​is the average number of repetitions and is a real number in the range of 1<n<15.)

[0016] In the formula (1), the value of n can be calculated from the number average molecular weight of the epoxy resin determined by gel permeation chromatography (GPC, detector: RI) or the area ratio of each separated peak. n is preferably a real number satisfying 1<n<15, more preferably 1<n<10, and particularly preferably 1<n<5.

[0017] The epoxy resin represented by the formula (1) can be obtained by reacting a phenol resin represented by the following formula (2) with epihalohydrin.

[0018]

[0019] (In formula (2), n is the average number of repetitions and is a real number in the range of 1<n<15.)

[0020] The preferred range of n in the formula (2) is the same as that in the formula (1).

[0021] The epihalohydrin is readily available on the market. The amount of epihalohydrin used is preferably 2.0 to 10 mol, more preferably 3.0 to 8.0 mol, and even more preferably 3.5 to 6.0 mol, per mol of hydroxyl groups in the raw material phenol mixture.

[0022] In the above reaction, an alkali metal hydroxide can be used as a catalyst to promote the epoxidation step. Usable alkali metal hydroxides include sodium hydroxide, potassium hydroxide, etc. A solid or an aqueous solution thereof may be used, but in this embodiment, a solid formed into flakes is preferably used from the viewpoints of solubility and handling. The amount of 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 material phenol mixture.

[0023] 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 the 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 material phenol mixture.

[0024] The reaction temperature is preferably 30 to 90°C, more preferably 35 to 80°C. In particular, in this embodiment, a temperature of 50°C or higher is preferred, and 60°C or higher is particularly preferred, for higher purity epoxidation. The reaction time is preferably 0.5 to 10 hours, more preferably 1 to 8 hours, and particularly preferably 1 to 3 hours. A short reaction time is not preferred because the reaction does not proceed fully, while a long reaction time is undesirable because by-products are formed. The reaction product of these epoxidation reactions is washed with water, or heated under reduced pressure without washing, to remove epihalohydrin and solvent. Furthermore, to obtain an epoxy resin with a reduced hydrolyzable halogen content, 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 the solution to carry out the reaction, ensuring ring closure. In this case, the amount of 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.

[0025] 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 the formula (1).

[0026] In the synthesis method of the phenolic resin represented by the formula (2), when furfural is reacted (condensed) with a phenol, the amount of the phenol is preferably 1.5 to 20 moles, particularly preferably 3 to 10 moles, per mole of furfural.

[0027] Examples of phenols include disubstituted phenols such as catechol, resorcinol, and hydroquinone, and monosubstituted phenols such as phenol, and these may be used alone or in combination of two or more.

[0028] Examples of the solvent include, but are not limited to, methanol, ethanol, propanol, isopropanol, toluene, xylene, etc., and these may be used alone or in combination of two or more. When a solvent is used, 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.

[0029] In the condensation reaction, a basic catalyst is preferably used. Polycondensation is possible with an acidic catalyst, but reactions between furfurals occur, resulting in increased by-products. Alternatively, a method using an organometallic compound can be used, but this is cost-inefficient. Specific examples of basic 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. However, the basic catalyst is not limited to these, and may be used alone or in combination of two or more. The amount of catalyst used is preferably 0.005 to 2.0 times, more preferably 0.01 to 1.1 times, the moles per mole of phenol.

[0030] 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 is repeatedly washed with water in the presence of a solvent, and then the water is separated and drained, and the solvent and unreacted materials are removed under heating and reduced pressure, thereby obtaining the phenolic resin represented by formula (2).

[0031] The curable resin composition of this embodiment contains a lignin-modified phenolic resin or a cashew-modified phenolic resin in addition to the epoxy resin represented by formula (1). Lignin-modified phenolic resins are phenolic resins modified with lignin, and one such resin is known from JP 2021-138806 A. Furthermore, PLN-0051LP, a lignin-modified phenolic resin, is available from AICA Kogyo Co., Ltd. Cashew-modified phenolic resins are phenolic resins modified with cashew oil, and one such resin is known from JP 2007-2032 A. The lignin-modified phenolic resin or cashew-modified phenolic resin is preferably present in an amount of 0.7 to 1.2 equivalents relative to 1 equivalent of epoxy groups in the epoxy resin represented by formula (1). If the amount is less than 0.7 equivalents or more than 1.2 equivalents relative to 1 equivalent of epoxy groups, curing may be incomplete, and good cured physical properties may not be obtained.

[0032] From the viewpoint of environmental issues, the biomass degree of the epoxy resin represented by formula (1) is preferably 20% or more. The biomass degree of the lignin-modified phenolic resin or cashew-modified phenolic resin is preferably 20% or more. The biomass degree of the curable resin composition of this embodiment is preferably 20% or more, and more preferably 25% or more. The upper limit of the biomass degree is not particularly limited and 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 used, such as petroleum, and is therefore meaningful in terms of sustainable resource use.

[0033] The biomass content of each material and curable resin composition can be determined by accelerator gravimetric analysis in accordance with ASTM D6866-21.

[0034] In the curable resin composition of this embodiment, the epoxy resin represented by formula (1) can 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 resins is preferably 5 to 95 wt %, more preferably 10 to 95 wt %, and even more preferably 15 to 95 wt %. If the amount added is too small, sufficient heat resistance may not be achieved.

[0035] 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, alkylaldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, etc.); polycondensates of the phenols with various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene, etc.); polycondensates of the phenols with aromatic dimethanols (benzenedimethanol, biphenyldimethanol, etc.); polycondensates of the phenols with aromatic dichloromethyls (α,α'-dichloroxylene, bischloromethylbiphenyl, etc.); polycondensates of the phenols with aromatic bisalkoxymethyls (bismethoxymethylbenzene, bismethoxymethylbiphenyl, bisphenoxymethylbiphenyl, etc.); and glycidyl ether epoxy resins, alicyclic epoxy resins, glycidylamine epoxy resins, and glycidyl ester epoxy resins obtained by glycidylating polycondensates of the bisphenols with various aldehydes or alcohols, 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. These are not limited to these, as long as they are commonly used epoxy resins. These may be used alone or in combination of two or more.In particular, it is preferable to use it in combination with an epoxy resin containing plant-derived components, as this can increase the biomass content.

[0036] The curable resin composition of this embodiment may contain a curing agent other than the guanine-modified phenolic resin or the cashew-modified phenolic resin. 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 and polyamide resins synthesized from a linoleic acid dimer and ethylenediamine;o-phenylenediamine, m-phenylenediamine, p-phenylenediamine, 4,4'-diaminodiphenyl 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'-diaminodiphenyl fluorene, 4,4'-diamino-3,3'-diethyl-5,5'-dimethyldiphenylmethane, 4,4'-diamino-3,3',5,5'-tetramethyldiphenylmethane, 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(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 aromatic amine compounds such as 1,3-bis(aminomethyl)cyclohexane, isophoronediamine, 4,4'-methylenebis(cyclohexylamine), norbornanediamine, ethylenediamine, propanediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, dimer diamine, and triethylenetetramine;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, alkylaldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, etc.), or polycondensates of the above phenols with various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydroindene, divinylbenzene, divinylbiphenyl, diisopropenylbiphenyl, butadiene, isoprene, etc.). Examples of the phenolic compounds include, but are not limited to, polymers of the phenols and ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, acetophenone, benzophenone, etc.), polycondensates of the phenols and aromatic dimethanols (benzenedimethanol, biphenyldimethanol, 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; and active ester compounds such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds.

[0037] The curable resin composition of the present embodiment may be used in combination with a curing accelerator. Examples of curing accelerators 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 octoate, 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 in an amount of 0.01 to 15 parts by weight per 100 parts by weight of the epoxy resin, if necessary.

[0038] An inorganic filler can be added to the curable resin composition of this embodiment 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, as well as spherical beads thereof. These fillers may be used alone or in combination of two or more. The amount of these inorganic fillers used varies depending on the application. For example, when used as an encapsulant for semiconductor elements, the inorganic fillers are preferably used in an amount of 20% by weight or more, more preferably 30% by weight or more, of the cured product of the curable resin composition in terms of heat resistance, moisture resistance, mechanical properties, and flame retardancy. In particular, the inorganic fillers are preferably used in an amount of 70 to 95% by weight to improve the linear expansion coefficient with the lead frame.

[0039] The curable resin composition of this embodiment can be blended with a release agent to improve release from the mold during molding. Any conventionally known release agent can be used, including 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. The blending amount of these release agents is preferably 0.5 to 3 wt % of the total organic components. If the amount is less than this, release from the mold is poor, and if the amount is too much, adhesion to a lead frame or the like is poor.

[0040] The curable resin composition of this embodiment can contain a coupling agent to enhance adhesion between the inorganic filler and the resin component. Any conventionally known coupling agent 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 first treating the surface of the inorganic filler with the coupling agent and then kneading it with the resin, or by mixing the coupling agent with the resin and then kneading the inorganic filler.

[0041] The curable resin composition of the present embodiment may contain known additives as needed. Specific examples of the additives that can be used include polybutadiene and modified polybutadiene, modified acrylonitrile copolymers, polyphenylene ether, polystyrene, polyethylene, polyimide, fluororesin, maleimide compounds, cyanate ester compounds, silicone gel, silicone oil, and colorants such as carbon black, phthalocyanine blue, and phthalocyanine green.

[0042] The curable resin composition of the present embodiment can be obtained by uniformly mixing the above-mentioned components. The method for producing the curable resin composition of the present embodiment is not particularly limited, but the composition can be obtained, for example, by thoroughly mixing an epoxy resin with a curing agent, a curing accelerator, an inorganic filler, a mold release agent, a silane coupling agent, additives, etc., using an extruder, kneader, rolls, planetary mixer, etc. until the mixture is uniform.

[0043] The obtained curable resin composition can be molded into various forms such as a resin sheet, a prepreg, etc. A prepreg form can be obtained, for example, by heating and melting the curable resin composition and / or a resin sheet of the present embodiment to reduce the viscosity and impregnating the composition into a fiber substrate.

[0044] The curable resin composition of this embodiment can also 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-like composition (hereinafter simply referred to as 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 dried by heating to produce a prepreg. In this case, the solvent is used in an amount that accounts for 10 to 70 wt %, preferably 15 to 70 wt %, of the mixture of the curable resin composition of this embodiment and the solvent.

[0045] The prepreg is cut into a desired shape, laminated, and then the epoxy resin composition is heat-cured while applying pressure to the laminate by press molding, autoclave molding, sheet winding molding, etc., to obtain a carbon fiber reinforced plastic (CFRP). Copper foil or an organic film can also be laminated during the lamination of the prepreg.

[0046] In addition to the above-mentioned methods, CFRP can also be obtained by molding using known methods, such as resin transfer molding (RTM), in which a carbon fiber substrate (usually a carbon fiber fabric) is cut, laminated, and shaped to produce a preform (a preform before being impregnated with resin), the preform is placed in a mold, the mold is closed, resin is injected to impregnate the preform, and the resin is cured, and the mold is then opened to remove the molded product. Also usable are types of RTM methods, such as the VaRTM method, the SCRIMP (Seeman's Composite Resin Infusion Molding Process), and the CAPRI (Controlled Atmospheric Pressure Resin Infusion) method, which is described in JP-A-2005-527410, in which a resin supply tank is evacuated to a pressure lower than atmospheric pressure, cyclic compression is used, and the net molding pressure is controlled to more appropriately control the resin injection process, particularly the VaRTM method. Furthermore, a film stacking method in which a fiber substrate is sandwiched between resin sheets (films), a method in which powdered resin is attached to a reinforcing fiber substrate to improve impregnation, a molding method in which a fluidized bed or fluid slurry method is used in the process of mixing resin into a fiber substrate (Powder Impregnated Yarn), and a method in which resin fibers are mixed into a fiber substrate can also be used.

[0047] Examples of carbon fibers include acrylic, pitch, and rayon carbon fibers, and among these, acrylic carbon fibers, which have high tensile strength, are preferably used. The carbon fiber may be in the form of twisted yarn, untwisted yarn, or non-twisted yarn, but untwisted yarn or non-twisted yarn is preferred because it provides a good balance between the formability and strength properties of the fiber-reinforced composite material.

[0048] The cured product of the curable resin composition of the present embodiment can be used for various applications other than the above-mentioned applications such as CFRP, and examples thereof include adhesives, paints, coating agents, molding materials (including sheets, films, CFRP, rotor fixing members, etc.), encapsulants for semiconductor elements, encapsulants for liquid crystal display elements, encapsulants for organic EL elements, electric and electronic parts such as printed wiring boards (BGA substrates, build-up substrates, etc.), 3D printing, and additives for other resins, etc.

[0049] Examples of the adhesive include adhesives for civil engineering, construction, automobiles, general office use, and medical use, as well as adhesives for electronic materials. Among these, adhesives for electronic materials include interlayer adhesives for multilayer substrates such as build-up substrates, 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 are applicable to a variety of uses.

[0050] When the curable resin composition of this embodiment is applied to an encapsulant for semiconductor elements, a lead frame equipped with a semiconductor element or a semiconductor package substrate is placed in a mold, and the curable resin composition of this embodiment is molded by a melt casting method, transfer molding method, injection molding method, compression molding method, or the like, and further heated for 2 to 10 hours at 80 to 200° C. 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.

[0051] When the curable resin composition of this embodiment is applied to printed wiring boards, it can be heated and melted to reduce viscosity, and then impregnated into reinforcing fibers such as glass fibers and polyamide 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, 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. Known weaving methods for woven fabrics include plain weave, sieve weave, and twill weave, and these known methods can be appropriately selected depending on the intended application and performance. Furthermore, woven fabrics that have been opened or surface-treated with a silane coupling agent or the like are preferably used. The thickness of the substrate is not particularly limited, but is preferably approximately 0.01 to 0.4 mm. Furthermore, a prepreg can be obtained by impregnating reinforcing fibers with the varnish and drying them under heat, and a copper clad laminate (CCL) can be produced from this. A laminate can also be produced using the curable resin composition of this embodiment by hot-press molding the obtained prepreg and CCL. The laminate is not particularly limited as long as it comprises one or more prepregs, and may also have any other layer. Furthermore, a sheet-like adhesive can be obtained by applying the varnish to a release film, removing the solvent under heat, and B-staging the adhesive. This sheet-like adhesive can be used as an interlayer insulating layer in a multilayer substrate or as an adhesive sheet for mounting semiconductors. The curable resin composition of this embodiment can also be suitably used for special substrate materials such as package substrates and HDIs (high density interconnects).

[0052] When the curable resin composition of this embodiment is used for a rotor fixing member, the curable resin composition of this embodiment is placed in a mold for the rotor fixing member, and molded by a melt casting method, transfer molding method, injection molding method, compression molding method, or the like, and then heated at 80 to 200°C for 2 to 10 hours to obtain a cured product.

[0053] The present invention will be explained in more detail below with reference to synthesis examples and working examples. The materials, processing details, 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. Unless otherwise specified, parts are parts by weight.

[0054] Various analytical methods were carried out under the following conditions. Epoxy equivalent: Measured according to the method described in JIS K-7236, and expressed in g / eq. Softening point: Measured according to the method conforming to JIS K-7234, and expressed in °C. Melt viscosity: Measured by the ICI melt viscosity (150°C) cone-plate method, and expressed in Pa s. Biomass content analysis (accelerator gravimetric analysis): Measured and calculated according to ASTM D6866-21, and expressed in %.

[0055] [Synthesis Example 1] 254 parts by weight of phenol, 63 parts by weight of water, and 27 parts by weight of sodium hydroxide were charged into a flask equipped with a stirrer, a reflux condenser, and a stirring device. After stirring and dissolving, the mixture was heated to 110°C, and 44 parts by weight of furfural was added dropwise over 2 hours. The mixture was then reacted at 110°C for 3 hours, and then heated to 145°C. During the temperature increase, the distilled water was removed from the system. After reaching 145°C, the mixture was reacted for 4 hours. The mixture was then cooled to 80°C, and 63 parts by weight of water was charged. 4 parts by weight of phosphoric acid and 63 parts by weight of 35% hydrochloric acid were added for neutralization. After repeated water washing, unreacted phenol was distilled off under reduced pressure with heating to obtain 109 parts by weight of a phenolic resin. To 78 parts by weight of the resulting phenolic resin, 254 parts by weight of epichlorohydrin (ECH), 64 parts by weight of dimethyl sulfoxide (DMSO), and 13 parts by weight of water were charged into a reaction vessel, heated, stirred, and dissolved. After that, 23 parts by weight of flaky sodium hydroxide was added in portions over 2 hours while maintaining the temperature at 45°C. The reaction was then continued for 2 hours at 45°C and 60 minutes at 70°C. The mixture was then repeatedly washed with water to remove by-product salts and dimethyl sulfoxide. The excess epichlorohydrin was then 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, and 7 parts by weight of a 30% aqueous sodium hydroxide solution was added. The reaction mixture was then allowed to react for 1 hour, after which the reaction solution was repeatedly washed with water until the washings became neutral. Next, methyl isobutyl ketone was distilled off from the oil layer under heating and reduced pressure, yielding 97 parts by weight of epoxy resin A represented by 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 repeat number n was 2.1 based on GPC, and the biomass content was 25%. The GPC chart of epoxy resin A is shown in Figure 1.

[0056] [Synthesis Example 2] A cashew-modified phenolic resin was synthesized according to JP 2007-2032 A. A flask equipped with a stirrer, reflux condenser, and stirring device was charged with 250 parts by weight of phenol, 138 parts by weight of 37% formalin, 110 parts by weight of cashew oil, and 2 parts by weight of sulfuric acid, and the mixture was allowed to react under reflux at 100°C for 1 hour. The mixture was then heated to 190°C while being distilled under reduced pressure, yielding 254 parts by weight of cashew-modified phenolic resin. The softening point of this resin was 80°C, and the biomass content was 31%.

[0057] Example 1 Epoxy resin A obtained in Synthesis Example 1 was used as the base resin, and lignin-modified phenolic resin (PLN-0051LP manufactured by AICA Kogyo Co., Ltd., softening point: 106°C, GPC chart shown in Figure 2) as a curing agent and triphenylphosphine (TPP) 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.

[0058] [Example 2] Epoxy resin A obtained in Synthesis Example 1 was used as the base resin, and the cashew-modified phenolic resin obtained in Synthesis Example 2 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 formulation in Table 1, and cured at 180°C for 6 hours to produce a cured product.

[0059] Comparative Example 1 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 group 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.

[0060] Physical properties were measured under the following conditions. <Heat resistance (Tg) measurement conditions> Dynamic viscoelasticity measuring device: TA-instruments, DMA-Q800 Measurement temperature range: 25 to 300°C Heating rate: 2°C / min Tg: The peak point of Tan δ was defined as Tg. <Dielectric constant and dielectric loss tangent test> Using a 10 GHz cavity resonator manufactured by AET Corporation, tests were conducted at 25°C using the cavity resonator perturbation method. The sample size was 2.5 mm wide x 50 mm long, and the thickness was 0.3 mm. <Tensile modulus and maximum tensile stress> Using an autograph AGS-X manufactured by Shimadzu Corporation, the test specimen was clamped to a length of 5 cm and tension measurements were taken in the 180° direction at the above test speed, with a tension speed of 0.5 mm / min.

[0061]

[0062] From the results in Table 1, it was confirmed that Examples 1 and 2 had a high degree of biomass, high heat resistance, low dielectric properties, and excellent mechanical properties.

Claims

1. A curable resin composition comprising an epoxy resin represented by the following formula (1) and a lignin-modified phenolic resin or a cashew-modified phenolic resin: (In formula (1), 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 claim 1, wherein the lignin-modified phenolic resin or the cashew-modified phenolic resin has a biomass content of 20% or more.

3. 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.

4. The curable resin composition according to claim 1, having a biomass content of 20% or more.

5. The curable resin composition according to any one of claims 1 to 4, which is for use in carbon fiber reinforced plastics.

6. The curable resin composition according to any one of claims 1 to 4, which is used as an encapsulating material for semiconductor elements.

7. The curable resin composition according to any one of claims 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 claims 1 to 4.

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