Curable resin, curable resin composition, varnish, and cured product of same

Abstract

The present invention not only has excellent solvent solubility and excellent storage stability as a varnish but also provides a cured product that has excellent dimensional stability and excellent low dielectric properties. A curable resin according to the present invention is formed by reacting: a vinylbenzyl compound (A) represented by formula (1); and a compound (B) that has a pKa of less than 31 in a dimethyl sulfoxide solvent. The HSP distance between the curable resin and toluene is no more than 2.5.　In formula (1), X represents a halogen atom, R1 represents a C1–20 alkyl group or a C6–20 aromatic group that may have a substituent, and s is an integer from 0 to 4, inclusive.

Description

Curable resin, curable resin composition, varnish and cured product thereof

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

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

[0003] Semiconductor packages (hereinafter referred to as PKGs) used in smartphones and other devices require thinner PKG substrates to meet demands for smaller size, thinner thickness, and higher density. However, thinner PKG substrates result in reduced rigidity, which can lead to defects such as significant warping caused by heating during solder mounting of the PKG to a motherboard (PCB). To alleviate this, there is a demand for PKG substrate materials that can reduce dimensional change from room temperature to the solder mounting temperature (260°C). Specific examples include high glass transition temperatures (Tg), low thermal expansion (linear expansion coefficient α1 / linear expansion coefficient α2), and high elasticity at high temperatures (Patent Document 1, Non-Patent Documents 1 and 2).

[0004] Furthermore, the fifth generation communication system "5G," currently being developed at an accelerated pace, is expected to further increase capacity and speed of communication. 5G will use higher frequencies, but reducing transmission loss is important to achieve high-speed communication using high frequencies, and board materials will be required to have even lower dielectric properties. Transmission loss that occurs on printed circuit boards is due to conductor loss and dielectric loss. As stated in Non-Patent Document 3, dielectric loss α D is the relative permittivity of the dielectric, ε ｒ and the dielectric loss tangent tanδ, the relative dielectric constant ε ｒIt can be said that improving the dielectric loss tangent tanδ, which has a large contribution to the above, is effective. Low-dielectric materials include thermoplastic materials such as PTFE (polytetrafluoroethylene) and LCP (liquid crystal polymer), but they are less moldable than thermosetting resins. In light of this, there is a need for the development of thermosetting resins with excellent low-dielectric properties.

[0005] In light of this situation, maleimide resins have recently been investigated as a printed wiring board material for high-frequency applications. Maleimide resins are characterized by high heat resistance and minimal dimensional change due to their high crosslink density. Additionally, their structural rigidity and symmetry make them less susceptible to molecular vibrations caused by high-frequency radio waves, making them promising materials with low dielectric properties. However, as pointed out in Patent Document 2, bismaleimide compounds with imide structures in their molecules are highly crystalline and have high melting points (approximately 150°C), close to the 170-180°C threshold for the initiation of self-reaction. Therefore, they are difficult to prepare impregnating varnishes for impregnation and drying, or to melt-mix with epoxy resins, curing agents, fillers, and the like to produce molding materials.

[0006] Japanese Patent Publication No. 2023-179928 Japanese Patent Publication No. 2006-213823

[0007] "Material Design of Bismaleimide-Based High Heat-Resistant Resins," Network Polymer, Vol. 38, No. 3, 2017, pp. 144-152; "Technology for Predicting Circuit Board Warpage Reflecting Changes in Physical Properties Due to Resin Curing Shrinkage," Journal of the Society of Smart Processing, Vol. 8, No. 5, September 2019, pp. 184-189; "Factors of Signal Loss in High-Speed ​​Signal Transmission on Printed Circuit Boards," 29th Japan Institute of Electronics Packaging Spring Conference, Session ID: 16P1-17, 2015.

[0008] The present invention has been made in view of these circumstances, and aims to provide a cured product that has excellent solvent solubility and storage stability in a varnish state, as well as excellent dimensional stability and low dielectric properties.

[0009] That is, the present invention relates to the following [1] to

[12] . In the present invention, "(numerical value 1) to (numerical value 2)" indicates that the upper and lower limits are included. [1] A curable resin obtained by reacting a vinylbenzyl compound (A) represented by the following formula (1) with a compound (B) having a pKa of less than 31 in a dimethyl sulfoxide solvent, and having an HSP distance to toluene of 2.5 or less.

[0010]

[0011] In formula (1), X represents a halogen atom. １ represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms which may have a substituent, and s is an integer from 0 to 4. [2] The curable resin according to the above item [1], wherein the compound (B) is a hydrocarbon compound and / or a carbonyl compound. [3] The curable resin according to the above item [1], wherein the compound (B) is a compound having at least one of the partial structures represented by the following formulas (2) to (5):

[0012]

[0013] In formula (2), Y ２ represents an alkylene group having 1 to 20 carbon atoms, an -O- group, or a -C(=O)- group, which may have a substituent. ２ R each independently represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms which may have a substituent. ２ "'" represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 6 to 20 carbon atoms which may have a substituent. Multiple s2's each exist independently and are integers of 0 to 4. A dotted line indicates that a bond may or may not be present.

[0014]

[0015] In formula (3), there are multiple R ３ each independently represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms which may have a substituent, and s3 is an integer of 0 to 4. A dotted line indicates that a bond may or may not be present.

[0016]

[0017] In formula (4), Y ４ represents a direct bond or an alkylene group having 1 to 10 carbon atoms which may have a substituent. ４ each independently represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms which may have a substituent, and s4 is an integer of 0 to 10. A dotted line indicates that a bond may or may not be present.

[0018] In formula (5), ring A represents a 5- to 8-membered aromatic ring. ５ each independently represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms, which may have a substituent; s51 is an integer from 0 to 3; and s52 is 0 to the maximum number of substitutions. [4] A curable resin composition containing the curable resin according to any one of the preceding items [1] to [3]. [5] The curable resin composition according to the preceding item [4], further containing at least one selected from the group consisting of maleimide resins, polyphenylene ether compounds, compounds having an ethylenically unsaturated bond, cyanate ester resins, polybutadiene and modified products thereof, polystyrene and modified products thereof, polyethylene and modified products thereof, benzoxazine resins, epoxy resins, active ester compounds, phenolic resins, amine resins, isocyanate resins, polyamide resins, polyimide resins, and active esters. [6] The curable resin composition according to the preceding item [4] or [5], further containing a curing accelerator. [7] The curable resin composition according to the preceding items [4] to [6], which is for use in a printed wiring board. [8] A varnish comprising the curable resin according to any one of the preceding items [1] to [3] and an organic solvent. [9] A varnish comprising the curable resin composition according to any one of the preceding items [4] to [7] and an organic solvent.

[10] A cured product obtained by curing the curable resin according to any one of the preceding items [1] to [3].

[12] A cured product obtained by curing the curable resin composition according to any one of the preceding items [4] to [7].

[0019] According to the present invention, it is possible to provide a cured product that has excellent solvent solubility and storage stability in the form of a varnish, as well as excellent dimensional stability and low dielectric properties.

[0020] Hereinafter, an embodiment of the present invention (hereinafter also referred to as "the present embodiment") will be described in further detail.

[0021] The curable resin of the present embodiment is obtained by reacting a vinylbenzyl compound (A) represented by the following formula (1) (hereinafter also simply referred to as "vinyl compound (A)") with a compound (B) having a pKa of less than 31 in a dimethyl sulfoxide solvent (hereinafter also simply referred to as "compound (B)").

[0022]

[0023] In formula (1), X represents a halogen atom. The halogen atom is preferably a bromine atom or a chlorine atom. １ represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms which may have a substituent; and s is an integer of 0 to 4.

[0024] In this embodiment, the pKa of compound (B) in dimethyl sulfoxide solvent is based on data published by Data Organic Chemistry, operated by the American Chemical Societies. For compounds not described in this publication, the pKa is calculated by a computational chemistry approach disclosed in a known publication, such as "Accurate pKa Determination for a Heterogeneous Group of Organic Molecules," ChemPhysChem 2004, Vol. 5, Issue 10, pp. 1513-1522. When the pKa of compound (B) is less than 31, a proton is easily released from compound (B) under basic conditions, and the anion of compound (B) thus generated attacks the halomethyl group in vinylbenzyl compound (A), resulting in a dehydrohalogenation reaction to produce a styrene compound. This reaction can be represented by the following formula:

[0025]

[0026] In the above formula, AH is compound (B), and A － is the anion of compound (B). Compound (B) is preferably a hydrocarbon compound or a carbonyl compound, and more preferably a compound having at least one of the partial structures represented by the following formulas (2) to (5):

[0027]

[0028] In formula (2), Y represents an alkylene group having 1 to 20 carbon atoms, an -O- group, or a -C(=O)- group, which may have a substituent. ２ R each independently represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms which may have a substituent. ２ ' represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 1 to 20 carbon atoms which may have a substituent. Multiple s2s each exist independently and are integers of 0 to 4. A dotted line indicates that a bond may or may not be present.

[0029]

[0030] In formula (3), there are multiple R ３ each independently represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms which may have a substituent, and s3 is an integer of 0 to 4. A dotted line indicates that a bond may or may not be present.

[0031]

[0032] In formula (4), Y ４ represents a direct bond or an alkylene group having 1 to 10 carbon atoms which may have a substituent. ４ each independently represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms which may have a substituent, and s4 is an integer of 0 to 10. A dotted line indicates that a bond may or may not be present.

[0033]

[0034] In formula (5), ring A represents a 5- to 8-membered aromatic ring. ５ each independently represents an alkyl group having 1 to 20 carbon atoms or an aromatic group having 6 to 20 carbon atoms which may have a substituent, and s51 is an integer from 0 to 3. s52 is from 0 to the maximum number of substitutions. The maximum number of substitutions is 3 if ring A is a 5-membered ring, 4 if it is a 6-membered ring, 5 if it is a 7-membered ring, and 6 if it is an 8-membered ring.

[0035] Among the compounds (B), examples of hydrocarbon compounds having a pKa of less than 31 include 9,10-dihydroanthracene, 2-methyl-9,10-dihydroanthracene, 9-methyl-9,10-dihydroanthracene, 2-ethyl-9,10-dihydroanthracene, 9-ethyl-9,10-dihydroanthracene, 2,3-dimethyl-9,10-dihydroanthracene, 9,9-dimethyl-9,10-dihydroanthracene, 9,10-dimethyl-9,10-dihydroanthracene, dibenzo-1,4-pyran, 2-methyl-9H-xanthene, 4- Methyl-9H-xanthene, 9-methyl-9H-xanthene, 2,4-dimethyl-9H-xanthene, 2,7-dimethyl-9H-xanthene, 2,9-dimethyl-9H-xanthene, 3,6-dimethyl-9H-xanthene, 1,3,6,8-tetramethyl-9H-xanthene, 2,4,5,7-tetramethyl-9H-xanthene, 2-methyl-9-ethyl-9H-xanthene, 9-isopropyl-9H-xanthene, 4-tert-butyl-9H-xanthene, anthrone, 3-methylanthrone, 10-methylanthracen-9(10H)-one, indole Indene, 1-methyl-1H-indene, 2-methyl-1H-indene, 3-methyl-1H-indene, 4-methyl-1H-indene, 5-methyl-1H-indene, 6-methyl-1H-indene, 7-methyl-1H-indene, 1,2-dimethyl-1H-indene, 1,3-dimethyl-1H-indene, 2,3-dimethyl-1H-indene, 2,4-dimethyl-1H-indene, 4,5-dimethyl-1H-indene, 4,6-dimethyl-1H-indene, 4,7-dimethyl-1H-indene, 5,6-dimethyl-1H-indene, 5,7-dimethyl-1H-indene indene, 6,7-dimethyl-1H-indene, 1-ethyl-1H-indene, 2-ethyl-1H-indene, 2-vinyl-1H-indene, 3-vinyl-1H-indene, fluorene, 1-methyl-9H-fluorene, 2-methyl-9H-fluorene, 3-methyl-9H-fluorene, 4-methyl-9H-fluorene, 9-methyl-9H-fluorene, 1,3-dimethyl-9H-fluorene, 1,8-dimethyl-9H-fluorene, 2,3-dimethyl-9H-fluorene, 2,4-dimethyl-9H-fluorene, 2,5-dimethyl-9H-fluorene, 2,Examples of fluorene include, but are not limited to, 7-dimethyl-9H-fluorene, 2,9-dimethyl-9H-fluorene, 3,5-dimethyl-9H-fluorene, 3,6-dimethyl-9H-fluorene, 4,5-dimethyl-9H-fluorene, 2-ethyl-9H-fluorene, 3-ethyl-9H-fluorene, 4-ethyl-9H-fluorene, 9-ethyl-9H-fluorene, 2-ethynyl-9H-fluorene, 2-vinylfluorene, azulene, and guaiazulene.

[0036] Among the compounds (B), examples of carbonyl compounds having a pKa of less than 31 include acetone, methyl ethyl ketone, 2-pentanone, 3-pentanone, 3-methyl-2-butanone, 3-methyl-3-buten-2-one, 3-penten-2-one, 4-penten-2-one, methyl vinyl ketone, 3-butyn-2-one, cyclobutanone, 2-methylcyclobutanone, 3-methylcyclobutanone, 2-cyclobuten-1-one, cyclopentanone, 2-methylcyclopentanone, 3-methylcyclopentanone, and 2-cyclopenten-1-one. Examples of the methyl acetophenone include, but are not limited to, 3-cyclopenten-1-one, cyclohexanone, 2-methylcyclohexanone, 3-methylcyclohexanone, 4-methylcyclohexanone, isophorone, acetophenone, 2'-methylacetophenone, 3'-methylacetophenone, 4'-methylacetophenone, propiophenone, 2'-methylpropiophenone, 3'-methylpropiophenone, 4'-methylpropiophenone, indan-1-one, indan-2-one, tetralin-1-one, and tetralin-2-one.

[0037] The compound (B) may be an oligomer obtained by oligomerizing the above-exemplified compound under either acidic or basic conditions.

[0038] The curable resin of this embodiment may be produced by any method, including but not limited to, reacting a vinylbenzyl compound (A) with a compound (B). Specifically, the curable resin may be produced by reacting the vinylbenzyl compound (A) with the compound (B) in an aprotic polar solvent in the presence of a basic catalyst. Examples of aprotic polar solvents include dimethyl sulfone, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, 1,3-dimethyl-2-imidazolidinone, and N-methylpyrrolidone, and two or more of these may be used in combination. Furthermore, if necessary, a non-aqueous solvent may also be used in combination. Examples of non-aqueous solvents 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 thereto. Two or more of these may also be used in combination. The catalyst is not particularly limited, and examples thereof include basic catalysts such as sodium hydroxide, potassium hydroxide, potassium carbonate, sodium methoxide, sodium ethoxide, and potassium tert-butoxide. The order of adding the vinylbenzyl compound (A), compound (B), and base can be changed as needed. However, a method in which compound (B), an aprotic polar solvent, and a base are added, compound (B) is sufficiently ionized, and then vinylbenzyl compound (A) is added is preferred because it is less likely to produce hydrolyzed vinylbenzyl compound (A). When the reaction is carried out without using an aprotic polar solvent, the reaction rate is significantly reduced. When an aprotic polar solvent is not used, the reaction is generally carried out using a phase transfer catalyst. In this case, the raw materials are dissolved in a non-aqueous solvent such as toluene, and compound (B) and vinylbenzyl compound (A) are reacted in the presence of a base catalyst such as aqueous sodium hydroxide solution or a phase transfer catalyst such as tetrabutylammonium bromide. In this case, it is difficult to completely remove the interlayer transfer catalyst such as tetrabutylammonium bromide, making it difficult to achieve low dielectric properties (low dielectric constant, low dielectric dissipation factor). In addition, the remaining interlayer transfer catalyst may cause problems such as ion migration when a substrate material using the compound of the present invention is subjected to a long-term moist heat reliability test or the like.The reaction temperature is preferably 0 to 100°C, more preferably 0 to 80°C, and even more preferably 0 to 60°C. If the temperature exceeds the upper limit, the compound of the present invention may undergo self-polymerization, resulting in gelation. If the temperature is below the lower limit, the reaction may not proceed sufficiently. If necessary, a polymerization inhibitor may be added during the reaction stage. Neutralization with an acid compound may be performed as post-reaction treatment. If necessary, an alcohol compound, water, or the like may be added to the reaction solution to recover the target product as crystals. The resulting reaction solution or crystals may be redissolved in a solvent and subjected to an extraction step. For the extraction step, aromatic hydrocarbon solvents such as toluene and xylene may be used alone, or non-aromatic hydrocarbons such as cyclohexane and toluene may be used in combination. After extraction, the organic layer is washed with water until the wastewater becomes neutral, and the solvent is removed using an evaporator or the like to obtain the target compound. To reduce tackiness, the product may be prepolymerized by heating or other methods.

[0039] The curable resin of this embodiment has excellent solubility in solvents. The type of solvent used is not limited, but the resin can be dissolved in a hydrocarbon solvent (toluene, xylene, mesitylene, etc.), a ketone solvent (acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexanone, etc.), an alcohol solvent (methanol, ethanol, isopropanol, butanol, etc.), or an aprotic polar solvent (dimethylformamide, dimethylacetamide, N-methylpyrrolidone, etc.). For use in combination with a material having low polarity and low dielectric properties, the resin is preferably soluble in a hydrocarbon solvent.

[0040] The curable resin of this embodiment has an HSP distance Ra with toluene of 2.5 or less, preferably 2.3 or less. If the HSP distance is within a predetermined range, the resin has excellent solvent solubility in toluene. Here, the HSP distance is the distance between two points in Hansen space. Hansen solubility parameters (HSP) include δd, δp, and δh, where δd represents the energy due to intermolecular dispersion forces, δp represents the energy due to intermolecular dipole interactions, and δh represents the energy due to intermolecular hydrogen bonds. δd, δp, and δh can be regarded as coordinates in three-dimensional space (Hansen space), and the closer the distance (HSP distance) between two points, the more easily they dissolve in each other. The HSP distance Ra with toluene is defined using the Hansen solubility parameter by the following formula and can be calculated using Hansen Solubility Parameter software (HSPiP: Hansen Solubility Parameter in Practice).

[0041]

[0042] In the above formula, Ra is the HSP distance between the curable resin of this embodiment and toluene, δd1 is the energy due to the dispersion force between toluene molecules, δd2 is the energy due to the dispersion force between the curable resin of this embodiment, δp1 is the energy due to the dipole interaction between toluene molecules, δp2 is the energy due to the dipole interaction between the curable resin of this embodiment, δh1 is the energy due to the hydrogen bonding between toluene molecules, and δh2 is the energy due to the hydrogen bonding between the curable resin of this embodiment. That is, (δd1, δp1, δh1) represent the coordinates in the Hansen space of toluene, and (δd2, δp2, δh2) represent the coordinates in the Hansen space of the curable resin of this embodiment.

[0043] The curable resin composition of this embodiment may contain any known material as long as it contains the curable resin of this embodiment. Specific examples include maleimide resins, phenolic resins, epoxy resins, amine resins, compounds containing ethylenically unsaturated bonds, isocyanate resins, polyamide resins, polyimide resins, cyanate ester resins, propenyl resins, methallyl resins, active ester resins, and benzoxazine resins. These may be used alone or in combination. Furthermore, in terms of the balance between heat resistance, adhesion, and dielectric properties, it is preferable to contain epoxy resins, compounds containing ethylenically unsaturated bonds, and cyanate ester resins. The inclusion of these curable resins can improve the brittleness of the cured product and adhesion to metals, thereby suppressing package cracking during solder reflow and reliability tests such as thermal cycling. The amount of these curable resins used is preferably 10 times or less by weight, more preferably 5 times or less, and particularly preferably 3 times or less by weight relative to the curable resin of this embodiment. The preferred lower limit is 0.5 times or more by weight, and even more preferably 1 time or more by weight. If the weight ratio is 10 times or less, the effects of the heat resistance and dielectric properties of the curable resin of this embodiment can be utilized.

[0044] Examples of the maleimide resin, phenol resin, epoxy resin, amine resin, compound containing an ethylenically unsaturated bond, isocyanate resin, polyamide resin, polyimide resin, cyanate ester resin, active ester resin, and benzoxazine resin that can be used include those exemplified below.

[0045] Maleimide resins: 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, m-phenylene bismaleimide, 2,2'-bis[4-(4-maleimidophenoxy)phenyl]propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 4,4'-diphenylether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene), Xyloc-type maleimide compounds (anilix maleimide, manufactured by Mitsui Chemicals Fine Co., Ltd.), biphenylaralkyl-type maleimide compounds (solidified by distilling off the solvent under reduced pressure from a resin solution containing the maleimide compound (M2) described in Example 4 of JP 2009-001783 A), bisaminocumylbenzene-type maleimide (maleimide compounds described in WO 2020 / 054601 A), maleimide compounds having an indane structure described in Japanese Patent No. 6629692 or WO 2020 / 217679, MATERIAL STAGE Vol. 18, No. 12 2019 "Continued Epoxy Resin CAS Number Story - Curing Agent CAS Number Memorandum No. 31 Bismaleimide (1)" and MATERIAL STAGE Vol. 19, No. 12 2019 2 2019 Maleimide compound described in "Continued Epoxy Resin CAS Number Story - Hardener CAS Number Memorandum No. 32 Bismaleimide (2)".

[0046] Phenolic resins: Polycondensates of phenols (phenol, alkyl-substituted phenols, aromatic-substituted phenols, hydroquinone, resorcinol, naphthol, alkyl-substituted naphthol, dihydroxybenzene, alkyl-substituted dihydroxybenzene, dihydroxynaphthalene, etc.) and various aldehydes (formaldehyde, acetaldehyde, alkylaldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, furfural, etc.), polycondensates of phenols and various diene compounds (dicyclopentadiene, terpenes, vinylcyclohexene, norbornadiene, vinylnorbornene, tetrahydrofuran, etc.), phenolic resins obtained by polycondensation of phenols and substituted biphenyls (4,4'-bis(chloromethyl)-1,1'-biphenyl and 4,4'-bis(methoxymethyl)-1,1'-biphenyl, etc.) or substituted phenyls (1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene and 1,4-bis(hydroxymethyl)benzene, etc.); polycondensates of bisphenols and various aldehydes; and polyphenylene ether compounds.

[0047] Any known polyphenylene ether compound may be used, but from the viewpoint of heat resistance and electrical properties, a polyphenylene ether compound having an ethylenically unsaturated double bond is preferred, and a polyphenylene ether compound having an acrylic group, a methacrylic group, or a styrene structure is more preferred. Commercially available products include SA-9000-111 (manufactured by SABIC Corporation, a polyphenylene ether compound having a methacrylic group), OPE (registered trademark)-2St 1200, and OPE-2St 2200 (manufactured by Mitsubishi Gas Chemical Company, a polyphenylene ether compound having a styrene structure). The number average molecular weight (Mn) of the polyphenylene ether compound is preferably 500 to 5,000, more preferably 2,000 to 5,000, and even more preferably 2,000 to 4,000. If the molecular weight is less than 500, the heat resistance of the cured product tends to be insufficient. Furthermore, if the molecular weight is greater than 5,000, the melt viscosity increases, and sufficient fluidity is not achieved, which tends to result in molding defects. Furthermore, reactivity decreases, the curing reaction takes a long time, and the amount of unreacted material not incorporated into the curing system increases, which tends to lower the glass transition temperature of the cured product and reduce the heat resistance of the cured product. If the number-average molecular weight of the polyphenylene ether compound is 500 to 5,000, it is possible to achieve excellent heat resistance and moldability while maintaining excellent dielectric properties. The number-average molecular weight here can be measured specifically using gel permeation chromatography or the like.

[0048] The polyphenylene ether compound may be one obtained by a polymerization reaction or one obtained by a redistribution reaction of a high-molecular-weight polyphenylene ether compound having a number-average molecular weight of approximately 10,000 to 30,000. Furthermore, these compounds may be used as raw materials and reacted with a compound having an ethylenically unsaturated double bond, such as methacryl chloride, acrylic chloride, or chloromethylstyrene, to impart radical polymerizability. A polyphenylene ether compound obtained by a redistribution reaction may be obtained, for example, by heating a high-molecular-weight polyphenylene ether compound in a solvent such as toluene in the presence of a phenolic compound and a radical initiator to cause a redistribution reaction. Such polyphenylene ether compounds obtained by a redistribution reaction are preferred because they have hydroxyl groups derived from phenolic compounds at both ends of the molecular chain that contribute to curing, thereby maintaining even higher heat resistance. Furthermore, functional groups can be introduced at both ends of the molecular chain even after modification with a compound having an ethylenically unsaturated double bond. Furthermore, polyphenylene ether compounds obtained by a polymerization reaction are preferred because they exhibit excellent fluidity.

[0049] In the case of polyphenylene ether compounds obtained by polymerization, the molecular weight of the polyphenylene ether compound can be adjusted by adjusting the polymerization conditions, etc. In the case of polyphenylene ether compounds obtained by redistribution, the molecular weight of the resulting polyphenylene ether compound can be adjusted by adjusting the conditions, etc. of the redistribution reaction. More specifically, adjusting the amount of the phenolic compound used in the redistribution reaction can be considered. That is, the greater the amount of the phenolic compound, the lower the molecular weight of the resulting polyphenylene ether compound. In this case, poly(2,6-dimethyl-1,4-phenylene ether) or the like can be used as the high-molecular-weight polyphenylene ether compound that undergoes the redistribution reaction. Furthermore, the phenolic compound used in the redistribution reaction is not particularly limited, but preferred are, for example, polyfunctional phenolic compounds having two or more phenolic hydroxyl groups per molecule, such as bisphenol A, phenol novolac, and cresol novolac. These compounds may be used alone or in combination of two or more.

[0050] The content of the polyphenylene ether compound is not particularly limited, but is preferably 10 to 90 wt %, and more preferably 20 to 80 wt %, relative to the total weight of the curable resin components. A polyphenylene ether compound content of 10 to 90 wt % is preferable in that it not only provides excellent heat resistance, etc., but also allows a cured product to fully exhibit the excellent dielectric properties of the polyphenylene ether compound.

[0051] Epoxy resins: glycidyl ether-based epoxy resins obtained by glycidylating the above-mentioned phenolic resins and alcohols, alicyclic epoxy resins typified by 4-vinyl-1-cyclohexene diepoxide and 3,4-epoxycyclohexylmethyl-3,4'-epoxycyclohexanecarboxylate, glycidylamine-based epoxy resins typified by tetraglycidyldiaminodiphenylmethane (TGDDM) and triglycidyl-p-aminophenol, and glycidyl ester-based epoxy resins.

[0052] Amine resins: diaminodiphenylmethane, diaminodiphenyl sulfone, isophoronediamine, naphthalenediamine, aniline novolak, orthoethylaniline novolak, aniline resins obtained by reacting aniline with xylylene chloride, and aniline and substituted biphenyls (4,4'-bis(chloromethyl)-1,1'-biphenyl, 4,4'-bis(methoxymethyl)-1,1'-biphenyl, etc.) or substituted phenyls (1,4-bis(chloromethyl)benzene, 1,4-bis(methoxymethyl)benzene, 1,4-bis(hydroxymethyl)benzene, etc.) described in Japanese Patent No. 6,429,862.

[0053] Compounds containing an ethylenically unsaturated bond: polycondensates of the above-mentioned phenol resins and ethylenically unsaturated bond-containing halogen-based compounds (chloromethylstyrene, allyl chloride, methallyl chloride, acrylic acid chloride, allyl chloride, etc.), polycondensates of ethylenically unsaturated bond-containing phenols (2-allylphenol, 2-propenylphenol, 4-allylphenol, 4-propenylphenol, eugenol, isoeugenol, etc.) and halogen-based compounds (4,4'-bis(methoxymethyl)-1,1'-biphenyl, 1,4-bis(chloromethyl)benzene, 4,4'-difluorobenzophenone, 4,4'-dichlorobenzophenone, 4,4'-dibromobenzophenone, cyanuric chloride, etc.), polycondensates of epoxy resins or alcohols and substituted or unsubstituted acrylates (acrylate, methacrylate, etc.), styrene resins, allyl Group-containing compounds, acenaphthyl group-containing compounds (acenaphthylene, etc.), isocyanuric acid derivatives (TAIC manufactured by Mitsubishi Chemical Corporation, MA-DGIC, DA-MGIC, MeDAIC, L-DAIC, DD-1 manufactured by Shikoku Chemicals, etc.), maleimide compounds (phenylmaleimide, 4,4'-diphenylmethane bismaleimide, polyphenylmethane maleimide, m-phenylene bismaleimide, 2,2'-bis[4-(4-maleimidophenoxy) (si) phenyl) propane, 3,3'-dimethyl-5,5'-diethyl-4,4'-diphenylmethane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 4,4'-diphenyl ether bismaleimide, 4,4'-diphenylsulfone bismaleimide, 1,3-bis(3-maleimidophenoxy)benzene, 1,3-bis(4-maleimidophenoxy)benzene), Zylok type maleimide resin (Anilix Maleimide, manufactured by Mitsui Chemicals Fine Co., Ltd.), biphenylaralkyl type maleimide resin (solidified by distilling off the solvent under reduced pressure from a resin solution containing the maleimide resin (M2) described in Example 4 of JP 2009-001783 A), bisaminocumylbenzene type maleimide (maleimide resin described in WO 2020 / 054601 A).

[0054] Isocyanate resins: aromatic diisocyanates such as p-phenylene diisocyanate, m-phenylene diisocyanate, p-xylene diisocyanate, m-xylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and naphthalene diisocyanate; aliphatic or alicyclic diisocyanates such as isophorone diisocyanate, hexamethylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, hydrogenated xylene diisocyanate, norbornene diisocyanate, and lysine diisocyanate; polyisocyanates such as biuret compounds of one or more types of isocyanate monomers or isocyanate compounds obtained by trimerizing the above diisocyanate compounds; and polyisocyanates obtained by a urethanization reaction of the above isocyanate compounds with polyol compounds.

[0055] Polyamide resin: a polymer made primarily from one or more amino acids (e.g., 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, para-aminomethylbenzoic acid, etc.) and lactams (e.g., ε-caprolactam, ω-undecanelactam, ω-laurolactam); or a polymer made primarily from one or more diamines and one or more dicarboxylic acids. Diamines: aliphatic diamines such as ethylenediamine, trimethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decanediamine, undecanediamine, dodecanediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, eicosanediamine, 2-methyl-1,5-diaminopentane, and 2-methyl-1,8-diaminooctane; alicyclic diamines such as cyclohexanediamine, bis-(4-aminocyclohexyl)methane, and bis(3-methyl-4-aminocyclohexyl)methane; and aromatic diamines such as xylylenediamine. Dicarboxylic acids: aliphatic dicarboxylic acids such as oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid; aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2-chloroterephthalic acid, 2-methylterephthalic acid, 5-methylisophthalic acid, 5-sodiumsulfoisophthalic acid, hexahydroterephthalic acid, and hexahydroisophthalic acid; alicyclic dicarboxylic acids such as cyclohexanedicarboxylic acid; and dialkyl esters and dichlorides of these dicarboxylic acids.

[0056] Polyimide resin: a polycondensate of the above diamine and a tetracarboxylic dianhydride. Tetracarboxylic dianhydride: 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'-diphenyl Sulfonetetracarboxylic dianhydride, 2,2',3,3'-biphenyltetracarboxylic dianhydride, methylene-4,4'-diphthalic dianhydride, 1,1-ethylidene-4,4'-diphthalic dianhydride, 2,2'-propylidene-4,4'-diphthalic dianhydride, 1,2-ethylene-4,4'-diphthalic dianhydride, 1,3-trimethylene-4,4'-diphthalic dianhydride, 1,4-tetramethylene-4,4'-diphthalic dianhydride, 1,5-pentamethylene-4,4'-diphthalic dianhydride, 4,4'-oxydiphthalic dianhydride , thio-4,4'-diphthalic dianhydride, sulfonyl-4,4'-diphthalic dianhydride, 1,3-bis(3,4-dicarboxyphenyl)benzene dianhydride, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride, 1,3-bis[2-(3,4-dicarboxyphenyl)-2-propyl]benzene dianhydride, 1,4-bis[2-(3,4-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 dianhydride, 1,4,5,8-Naphthalenetetracarboxylic dianhydride, 1,2,5,6-naphthalenetetracarboxylic dianhydride, 3,4,9,10-perylenetetracarboxylic dianhydride, 2,3,6,7-anthracenetetracarboxylic dianhydride, 1,2,7,8-phenanthrenetetracarboxylic dianhydride, ethylenetetracarboxylic dianhydride, 1,2,3,4-butanetetracarboxylic dianhydride, 1,2,3,4-cyclobutanetetracarboxylic dianhydride, cyclopentanetetracarboxylic dianhydride, cyclohexane -1,2,3,4-tetracarboxylic acid dianhydride, cyclohexane-1,2,4,5-tetracarboxylic acid dianhydride, 3,3',4,4'-bicyclohexyltetracarboxylic acid 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, 1,1-ethylidene-4,4'-bis(cyclohexane- 1,2-dicarboxylic acid) dianhydride, 2,2-propylidene-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, oxy-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, thio-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, sulfonyl-4,4'-bis(cyclohexane-1,2-dicarboxylic acid) dianhydride, bicyclo[2,2,2]oct-7-ene-2,3,5,6-tetracarboxylic acid dianhydride, rel-[1S,5R,6R] -3-oxabicyclo[3,2,1]octane-2,4-dione-6-spiro-3'-(tetrahydrofuran-2',5'-dione), 4-(2,5-dioxotetrahydrofuran-3-yl)-1,2,3,4-tetrahydronaphthalene-1,2-dicarboxylic anhydride, ethylene glycol-bis-(3,4-dicarboxylic anhydride phenyl) ether, 4,4'-biphenylbis(trimellitic acid monoester acid anhydride), 9,9'-bis(3,4-dicarboxyphenyl)fluorene dianhydride.

[0057] Cyanate ester resin: a cyanate ester compound obtained by reacting a phenolic resin with a cyanogen halide. Specific examples include dicyanatobenzene, tricyanatobenzene, dicyanatonaphthalene, dicyanatobiphenyl, 2,2'-bis(4-cyanatophenyl)propane (BisA-OCN, manufactured by Mitsubishi Gas Chemical Company, Inc.), bis(4-cyanatophenyl)methane, bis(3,5-dimethyl-4-cyanatophenyl)methane, 2,2'-bis(3,5-dimethyl-4-cyanatophenyl)propane, 2,2'-bis(4-cyanatophenyl)ethane, 2,2'-bis(4-cyanatophenyl)hexafluoropropane, bis(4-cyanatophenyl)sulfone, bis(4-cyanatophenyl)thioether, phenol novolac cyanate, and phenol-dicyclopentadiene co-condensates in which the hydroxyl groups have been converted to cyanate groups, but are not limited to these. Furthermore, the cyanate ester compound, the synthesis method of which is described in Japanese Patent Application Laid-Open No. 2005-264154, is particularly preferred as a cyanate ester compound due to its low moisture absorption, flame retardancy, and excellent dielectric properties. If necessary, the cyanate ester resin may contain a catalyst such as zinc naphthenate, cobalt naphthenate, copper naphthenate, lead naphthenate, zinc octoate, tin octoate, lead acetylacetonate, dibutyltin maleate, or commercially available 18% Octope Zn (manufactured by Hope Pharmaceutical Co., Ltd.) to trimerize the cyanate group to form a sym-triazine ring. The catalyst is typically used in an amount of 0.0001 to 0.10 parts by weight, preferably 0.00015 to 0.0015 parts by weight, per 100 parts by weight of the total weight of the curable resin composition.

[0058] Active ester resin: A compound having one or more active ester groups per molecule can be used as a curing agent for curable resins other than the maleimide resin mixture of this embodiment, such as epoxy resins, if necessary. Preferred active ester resins are compounds having two or more highly reactive ester groups per molecule, such as phenol esters, thiophenol esters, N-hydroxyamine esters, and esters of heterocyclic hydroxy compounds. The active ester resin is preferably one obtained by a condensation reaction between at least one of a carboxylic acid compound and a thiocarboxylic acid compound and at least one of a hydroxy compound and a thiol compound. In particular, from the viewpoint of improving heat resistance, active ester resins obtained from a carboxylic acid compound and a hydroxy compound are preferred, and active ester resins obtained from a carboxylic acid compound and at least one of a phenol compound and a naphthol compound are preferred. Examples of carboxylic acid compounds include benzoic acid, acetic acid, succinic acid, maleic acid, itaconic acid, phthalic acid, isophthalic acid, terephthalic acid, and pyromellitic acid. Examples of phenol compounds or naphthol compounds include hydroquinone, resorcinol, bisphenol A, bisphenol F, bisphenol S, phenolphthalene, methylated bisphenol A, methylated bisphenol F, methylated bisphenol S, phenol, o-cresol, m-cresol, p-cresol, catechol, α-naphthol, β-naphthol, 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, dihydroxybenzophenone, trihydroxybenzophenone, tetrahydroxybenzophenone, phloroglucin, benzenetriol, dicyclopentadiene-type diphenol compounds, phenol novolak, etc. Here, "dicyclopentadiene-type diphenol compounds" refers to diphenol compounds obtained by condensing one dicyclopentadiene molecule with two phenol molecules.Preferred specific examples of the active ester resin include active ester resins containing a dicyclopentadiene-type diphenol structure, active ester resins containing a naphthalene structure, active ester resins containing an acetylated product of phenol novolac, and active ester resins containing a benzoylated product of phenol novolac. Among these, active ester resins containing a naphthalene structure and active ester resins containing a dicyclopentadiene-type diphenol structure are more preferred. The "dicyclopentadiene-type diphenol structure" refers to a divalent structural unit consisting of phenylene-dicyclopentylene-phenylene. Commercially available active ester resins 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 resins containing a dicyclopentadiene-type diphenol structure; "Unifiner Series" (manufactured by Unitika Ltd.) as active ester resins containing a bisphenol A-type structure; and "EXB94" as active ester resins containing a naphthalene structure. 16-70BK" (manufactured by DIC Corporation); an activated ester resin containing an acetylated product of phenol novolac is "DC808" (manufactured by Mitsubishi Chemical Corporation); activated ester resins containing a benzoylated product of phenol novolac are "YLH1026," "YLH1030," and "YLH1048" (manufactured by Mitsubishi Chemical Corporation); an activated ester resin which is an acetylated product of phenol novolac is "DC808" (manufactured by Mitsubishi Chemical Corporation); and an activated ester resin containing a phosphorus atom is "EXB-9050L-62M" (manufactured by DIC Corporation).

[0059] Benzoxazine resin: The benzoxazine resin is not particularly limited as long as it is a resin having two or more benzoxazine rings in one molecule, but can be obtained, for example, by heating and reacting a phenol compound, an amine compound, and an aldehyde compound. The phenol compounds and amine compounds that can be used here are as described above. Examples of aldehyde compounds include formaldehyde, acetaldehyde, alkyl aldehyde, benzaldehyde, alkyl-substituted benzaldehyde, hydroxybenzaldehyde, naphthaldehyde, glutaraldehyde, phthalaldehyde, crotonaldehyde, cinnamaldehyde, and furfural.

[0060] The curable composition of this embodiment may contain a polymerization inhibitor. The inclusion of a polymerization inhibitor improves storage stability and allows for control of the reaction initiation temperature. Controlling the reaction initiation temperature facilitates ensuring fluidity, preventing impregnation into glass cloth and facilitating B-staging, such as prepreg formation. If the polymerization reaction proceeds too quickly during prepreg formation, problems such as difficulty in lamination during the lamination process are likely to occur. Usable polymerization inhibitors include phenol-based, sulfur-based, phosphorus-based, hindered amine-based, nitroso-based, and nitroxyl radical-based inhibitors. The polymerization inhibitor may be added during or after synthesis of the maleimide resin mixture of this embodiment. The polymerization inhibitors may be used alone or in combination of two or more. The amount of polymerization inhibitor used is typically 0.008 to 1 part by weight, preferably 0.01 to 0.5 parts by weight, per 100 parts by weight of the resin component. These polymerization inhibitors may be used alone, or two or more may be used in combination. In this embodiment, phenol-based, hindered amine-based, nitroso-based, and nitroxyl radical-based compounds are preferred.

[0061] Specific examples of 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, Monophenols such as 2,2'-methylenebis(4-methyl-6-t-butylphenol), 2,2'-methylenebis(4-ethyl-6-t-butylphenol), 4,4'-thiobis(3-methyl-6-t-butylphenol), 4,4'-butylidenebis(3-methyl-6-t-butylphenol), Triethylene glycol-bis[3-(3-t-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], N,N'-hexamethylenebis(3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), 2,2-thio-diethylenebis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate] ) propionate], 3,5-di-t-butyl-4-hydroxybenzylphosphonate-diethyl ester, 3,9-bis[1,1-dimethyl-2-{β-(3-t-butyl-4-hydroxy-5-methylphenyl)propionyloxy}ethyl]2,4,8,10-tetraoxaspiro[5,5]undecane, bis(3,5-di-t-butyl-4-hydroxybenzylsulfonate)calcium and other bisphenols;Examples include polymeric phenols such as 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-(3,5-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.

[0062] Specific examples of sulfur-based polymerization inhibitors include dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate.

[0063] Specific examples of phosphorus-based polymerization inhibitors include triphenyl phosphite, diphenyl isodecyl phosphite, phenyl diisodecyl phosphite, tris(nonylphenyl) phosphite, diisodecyl pentaerythritol phosphite, tris(2,4-di-t-butylphenyl) phosphite, cyclic neopentane tetrayl bis(octadecyl) phosphite, cyclic neopentane tetrayl bi(2,4-di-t-butylphenyl) phosphite, and cyclic neopentane tetrayl bi(2,4-di-t-butyl-4-methylphenyl) phosphite. and phosphites such as bis[2-t-butyl-6-methyl-4-{2-(octadecyloxycarbonyl)ethyl}phenyl]hydrogen phosphite; and oxaphosphaphenanthrene oxides such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, 10-(3,5-di-t-butyl-4-hydroxybenzyl)-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, and 10-decyloxy-9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide.

[0064] Specific examples of hindered amine polymerization inhibitors include ADK STAB (registered trademark) LA-40MP, ADK STAB LA-40Si, ADK STAB LA-402AF, ADK STAB LA-87, ADK STAB LA-82, ADK STAB LA-81, ADK STAB LA-77Y, ADK STAB LA-77G, ADK STAB LA-72, ADK STAB LA-68, ADK STAB LA-63P, ADK STAB LA-57, and ADK STAB LA-52 (all of which are manufactured by Adeka Chemical Co., Ltd.). Examples of the solvent include, but are not limited to, Tinuvin (registered trademark), Tinuvin 2020FDL, Tinuvin 944FDL, Chimassorb 944LD, Tinuvin (registered trademark), Tinuvin 622SF, Tinuvin PA144, Tinuvin 765, Tinuvin 770DF, Tinuvin XT55FB, Tinuvin 111FDL, Tinuvin 783FDL, and Tinuvin 791FB (manufactured by BASF).

[0065] Specific examples of the nitroso-based polymerization inhibitor include p-nitrosophenol, N-nitrosodiphenylamine, and the ammonium salt of N-nitrosophenylhydroxyamine (cupferron), with the ammonium salt of N-nitrosophenylhydroxyamine (cupferron) being preferred.

[0066] Specific examples of nitroxyl radical polymerization inhibitors include di-tert-butyl nitroxide, 2,2,6,6-tetramethylpiperidine-1-oxyl, 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-amino-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-methoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-acetoxy-2,2,6,6-tetramethylpiperidine-1-oxyl, 4-benzoyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl, and the like, but are not limited to these.

[0067] The curable resin composition of the present embodiment can also be used in combination with a curing accelerator (curing catalyst) to improve the curability. Specific examples of curing accelerators that can be used include radical polymerization initiators, which are preferably used for the purpose of promoting self-polymerization of radically polymerizable curable resins such as olefin compounds and maleimide resins, or radical polymerization with other components. Examples of the radical polymerization initiator that can be used include ketone peroxides such as methyl ethyl ketone peroxide and acetylacetone peroxide, diacyl peroxides such as benzoyl peroxide, dialkyl peroxides such as dicumyl peroxide and 1,3-bis-(t-butylperoxyisopropyl)-benzene, peroxyketals such as t-butyl peroxybenzoate and 1,1-di-t-butylperoxycyclohexane, α-cumylperoxyneodecanoate, t-butylperoxyneodecanoate, t-butylperoxypivalate, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, t-amylperoxy-2-ethylhexanoate, t-butylperoxy-2-ethylhexanoate, and t-amylperoxy-3,5,5-trimethylhexanoate. peroxycarbonates such as di-2-ethylhexyl peroxydicarbonate, bis(4-t-butylcyclohexyl)peroxydicarbonate, t-butylperoxyisopropyl carbonate, 1,6-bis(t-butylperoxycarbonyloxy)hexane; organic peroxides such as t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctoate, lauroyl peroxide; and known curing accelerators such as azo compounds such as azobisisobutyronitrile, 4,4'-azobis(4-cyanovaleric acid), and 2,2'-azobis(2,4-dimethylvaleronitrile), but are not particularly limited thereto. Ketone peroxides, diacyl peroxides, hydroperoxides, dialkyl peroxides, peroxyketals, alkyl peresters, percarbonates, etc. are preferred, and dialkyl peroxides are more preferred.The amount of radical polymerization initiator added is preferably 0.01 to 5 parts by weight, and particularly preferably 0.01 to 3 parts by weight, per 100 parts by weight of the curable resin composition. If the amount of radical polymerization initiator used is too large, the molecular weight does not sufficiently elongate during the polymerization reaction.

[0068] Furthermore, if necessary, a curing accelerator other than the radical polymerization initiator may be added or used in combination. Specific examples of the curing accelerator that can be used include imidazoles such as 2-methylimidazole, 2-ethylimidazole, and 2-ethyl-4-methylimidazole, tertiary amines such as 2-(dimethylaminomethyl)phenol and 1,8-diaza-bicyclo(5,4,0)undecene-7, phosphines such as triphenylphosphine, quaternary ammonium salts such as tetrabutylammonium salt, triisopropylmethylammonium salt, trimethyldecanylammonium salt, cetyltrimethylammonium salt, and hexadecyltrimethylammonium hydroxide, and triphenylammonium salts such as tetrabutylammonium salt, triisopropylmethylammonium salt, trimethyldecanylammonium salt, cetyltrimethylammonium salt, and hexadecyltrimethylammonium hydroxide. Examples of the curing accelerator include quaternary phosphonium salts such as phenylbenzylphosphonium salt, triphenylethylphosphonium salt, and tetrabutylphosphonium salt (the counter ion of the quaternary salt may be a halogen, an organic acid ion, a hydroxide ion, or the like, and is not particularly limited, but organic acid ions and hydroxide ions are particularly preferred), and transition metal compounds (transition metal salts) such as zinc compounds such as tin octoate, zinc carboxylate (zinc 2-ethylhexanoate, zinc stearate, zinc behenate, zinc myristylate), and zinc phosphate esters (zinc octylphosphate, zinc stearylphosphate, etc.). The curing accelerator is used in an amount of 0.01 to 5.0 parts by weight per 100 parts by weight of the epoxy resin, as needed.

[0069] The curable resin composition of this embodiment may contain a phosphorus-containing compound as a flame retardant-imparting component. The phosphorus-containing compound may be a reactive type or an additive type. Specific examples of the phosphorus-containing compound include phosphate esters such as trimethyl phosphate, triethyl phosphate, tricresyl phosphate, trixylylenyl phosphate, cresyl diphenyl phosphate, cresyl-2,6-dixylylenyl phosphate, 1,3-phenylenebis(dixylylenyl phosphate), 1,4-phenylenebis(dixylylenyl phosphate), and 4,4'-biphenyl(dixylylenyl phosphate); 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 10(2,5- Examples of suitable compounds include phosphanes such as (dihydroxyphenyl)-10H-9-oxa-10-phosphaphenanthrene-10-oxide; phosphorus-containing epoxy compounds obtained by reacting an epoxy resin with the active hydrogen of the phosphanes; and red phosphorus. However, phosphate esters, phosphanes, or phosphorus-containing epoxy compounds are preferred, with 1,3-phenylenebis(dixylylenyl phosphate), 1,4-phenylenebis(dixylylenyl phosphate), 4,4'-biphenyl(dixylylenyl phosphate), or phosphorus-containing epoxy compounds being particularly preferred. The content of the phosphorus-containing compound is preferably in the range of 0.1 to 0.6 (weight ratio) (phosphorus-containing compound) / (total epoxy resin). If the ratio is 0.1 or less, flame retardancy is insufficient, while if it is 0.6 or more, there is a concern that the moisture absorption and dielectric properties of the cured product may be adversely affected.

[0070] Furthermore, a light stabilizer may be added to the curable resin composition of this embodiment as needed. As the light stabilizer, a hindered amine light stabilizer (Hindered Amine Light Stabilizers, HALS) or the like is suitable. HALS is not particularly limited, but typical examples include polycondensates 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, polycondensates of dimethyl succinate-1-(2-hydroxyethyl)-4-hydroxy-2,2,6,6-tetramethylpiperidine, 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) bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, bis(2,2,6,6-tetramethyl-4-piperidyl)sebacate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, bis(1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl)sebacate, 2-(3,5-di-t-butyl-4-hydroxybenzyl)-2-n-butylmalonate bis(1,2,2,6,6-pentamethyl-4-piperidyl), and the like. Only one type of HALS may be used, or two or more types may be used in combination.

[0071] Furthermore, a binder resin can be blended into the curable resin composition of this embodiment as needed. Examples of binder resins include, but are not limited to, butyral resins, acetal resins, acrylic resins, epoxy-nylon resins, NBR-phenol resins, epoxy-NBR resins, polyamide resins, polyimide resins, and silicone resins. The blending amount of the binder resin is preferably within a range that does not impair the flame retardancy and heat resistance of the cured product, and is preferably 0.05 to 50 parts by weight, more preferably 0.05 to 20 parts by weight, per 100 parts by weight of the resin component, as needed.

[0072] Furthermore, to the curable resin composition of this embodiment, if necessary, inorganic fillers such as 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 spherical or crushed versions of these, may be added. In particular, when a curable resin composition for semiconductor encapsulation is obtained, the amount of the inorganic filler used is typically 80 to 92 wt %, and preferably 83 to 90 wt %, of the curable resin composition.

[0073] The curable resin composition of this embodiment can contain known additives as needed. Specific examples of usable additives include polybutadiene and modified products thereof, modified products of acrylonitrile copolymers, polyphenylene ether, polystyrene, polyethylene, polyimide, fluororesin, silicone gel, silicone oil, surface treatment agents for fillers such as silane coupling agents, mold release agents, and colorants such as carbon black, phthalocyanine blue, and phthalocyanine green. The amount of these additives to be added is preferably 1,000 parts by weight or less, more preferably 700 parts by weight or less, per 100 parts by weight of the curable resin composition. From the viewpoints of low water absorption and electrical properties, polybutadiene and modified products thereof, polyphenylene ether, polystyrene, polyethylene, fluororesin, etc. are preferred. From the viewpoints of electrical properties, adhesion, and low water absorption, polybutadiene and modified products thereof are preferred. Specific examples include butadiene-based thermoplastic elastomers such as styrene-butadiene copolymers (SBR: RICON-100, RICON-181, RICON-184, all manufactured by Cray Valley Corporation, etc.) and acrylonitrile-butadiene copolymers; and styrene-based thermoplastic elastomers such as styrene-butadiene-styrene copolymers (SBS), hydrogenated styrene-butadiene-styrene copolymers, styrene-isoprene-styrene copolymers (SIS), hydrogenated styrene-isoprene-styrene copolymers, and hydrogenated styrene (butadiene / isoprene)-styrene copolymers. These styrene-based thermoplastic elastomers may be used alone or in combination of two or more. Among these high molecular weight materials, styrene-based thermoplastic elastomers such as styrene-butadiene-styrene copolymer, hydrogenated styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, hydrogenated styrene-isoprene-styrene copolymer, and hydrogenated styrene-(butadiene / isoprene)-styrene copolymer are preferred, and styrene-isoprene-styrene copolymer, hydrogenated styrene-butadiene-styrene copolymer, hydrogenated styrene-isoprene-styrene copolymer, and hydrogenated styrene-(butadiene / isoprene)-styrene copolymer are more preferred because they have higher heat resistance and are less susceptible to oxidative degradation.Specifically, Septon 1020, Septon 2002, Septon 2004F, Septon 2005, Septon 2006, Septon 2063, Septon 2104, Septon 4003, Septon 4044, Septon 4055, Septon 4077, Septon 4099, Septon 8004, Septon 8006, Septon 8007L, Septon HG252, Septon V9827, Hybra 7125 (hydrogenated), Hybra 7215F, and Hybra 7311F. (All manufactured by Kuraray Co., Ltd.) Furthermore, the weight-average molecular weight of the styrene-based thermoplastic elastomer is not particularly limited as long as it is 10,000 or greater. However, if it is too large, compatibility with polyphenylene ether compounds, as well as with low-molecular-weight components with weight-average molecular weights of approximately 50 to 1,000 and oligomer components with weight-average molecular weights of approximately 1,000 to 5,000, becomes poor, making it difficult to ensure mixing and solvent stability. Therefore, a weight-average molecular weight of approximately 10,000 to 300,000 is preferred. Generally, compounds containing heteroatoms such as oxygen and nitrogen, such as bismaleimides and polymaleimides, have difficulty ensuring compatibility with low-polarity compounds, such as compounds composed primarily of hydrocarbons or compounds composed solely of hydrocarbons, among the additives and curable resin components, due to their polarity. On the other hand, the curable resin of this embodiment does not have a backbone design that actively incorporates heteroatoms such as oxygen and nitrogen (i.e., few polar groups), and therefore exhibits excellent compatibility with materials with low polarity and low dielectric properties and compounds composed solely of hydrocarbons.

[0074] The curable resin composition of this embodiment can be obtained by uniformly mixing the above components in a predetermined ratio, and is typically pre-cured at 130 to 180°C for 30 to 500 seconds, and then post-cured at 150 to 250°C for 2 to 15 hours, thereby allowing the curing reaction to proceed sufficiently and producing a cured product of this embodiment. Alternatively, the components of the curable resin composition can be uniformly dispersed or dissolved in a solvent or the like, and the solvent can be removed before curing.

[0075] The curable resin composition of this embodiment obtained in this manner has moisture resistance, heat resistance, and high adhesion. Therefore, the curable resin composition of this embodiment can be used in a wide range of fields requiring moisture resistance, heat resistance, and high adhesion. Specifically, it is useful as a material for all electrical and electronic components, such as insulating materials, laminates (printed wiring boards, BGA substrates, build-up substrates, etc.), encapsulating materials, and resists. It can also be used in fields such as molding materials, composite materials, paint materials, adhesives, and 3D printing. In particular, solder reflow resistance is beneficial in semiconductor encapsulation.

[0076] The semiconductor device may be encapsulated with the curable resin composition of the present embodiment, and examples of the semiconductor device include a DIP (dual in-line package), a QFP (quad flat package), a BGA (ball grid array), a CSP (chip size package), a SOP (small outline package), a TSOP (thin small outline package), and a TQFP (thin quad flat package).

[0077] The method for preparing the curable resin composition of this embodiment is not particularly limited, and the components may be simply mixed uniformly, or may be prepolymerized. For example, the curable resin of this embodiment may be prepolymerized by heating it in the presence or absence of a catalyst and in the presence or absence of a solvent. Similarly, in addition to the curable resin of this embodiment, a curing agent such as an epoxy resin, an amine compound, a maleimide compound, a cyanate ester compound, a phenolic resin, or an acid anhydride compound, and other additives may be added to form a prepolymer. The components may be mixed or prepolymerized using, for example, an extruder, kneader, or roll in the absence of a solvent, or using a reaction vessel equipped with a stirrer in the presence of a solvent.

[0078] The uniform mixing method involves kneading the components using a device such as a kneader, roll, or planetary mixer at a temperature within the range of 50 to 100°C to obtain a uniform resin composition. The resulting resin composition can be pulverized and then molded into cylindrical tablets using a molding machine such as a tablet machine, or into granular powder or powder-like 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 curable resin compositions. The resulting molded bodies are non-sticky at 0 to 20°C, and exhibit little loss in fluidity or curability even when stored at -25 to 0°C for one week or more. The resulting molded bodies can be molded into cured products using a transfer molding machine or compression molding machine.

[0079] An organic solvent can also be added to the curable resin composition of this embodiment to form a varnish-like composition (hereinafter simply referred to as varnish). The curable resin composition of this embodiment can be dissolved in a solvent such as toluene, xylene, acetone, methyl ethyl ketone, methyl isobutyl ketone, dimethylformamide, dimethylacetamide, or N-methylpyrrolidone, as needed, to form a varnish. This varnish is then impregnated into a substrate such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, alumina fiber, or paper, and heated and dried to obtain a prepreg. This prepreg can then be hot-press molded to form a cured product of the curable resin composition of this embodiment. The solvent used in this process typically accounts for 10 to 70 wt %, preferably 15 to 70 wt %, of the mixture of the curable resin composition of this embodiment and the solvent. Furthermore, if the composition is in liquid form, a cured curable resin containing carbon fiber can also be obtained as is, for example, by the RTM (Resin Transfer Molding) method.

[0080] The curable composition of this embodiment can also be used as a modifier for a film-type composition. Specifically, it can be used to improve flexibility and the like in the B-stage. Such a film-type resin composition can be obtained as a sheet-like adhesive by applying the curable resin composition of this embodiment as a curable resin composition varnish onto a release film, removing the solvent under heating, and then performing B-staging. This sheet-like adhesive can be used as an interlayer insulating layer in a multilayer substrate or the like.

[0081] The curable resin composition of this embodiment can be heated and melted to reduce viscosity, and then impregnated into reinforcing fibers such as glass fiber, carbon fiber, polyester fiber, polyamide fiber, and alumina fiber to obtain a prepreg. Specific examples include glass fibers such as E-glass cloth, D-glass cloth, S-glass cloth, Q-glass cloth, spherical glass cloth, NE-glass cloth, and T-glass cloth; inorganic fibers other than glass; polyparaphenylene terephthalamide (Kevlar®, manufactured by DuPont Co., Ltd.); wholly aromatic polyamide; polyester; and organic fibers such as polyparaphenylene benzoxazole, polyimide, and carbon fiber, but are not limited thereto. The shape of the substrate is not particularly limited, but examples include woven fabric, nonwoven fabric, roving, and chopped strand mat. Known weaving methods for woven fabrics include plain weave, saddle-weave, and twill weave, and these known methods can be appropriately selected and used depending on the intended application and performance. Also preferred are woven fabrics that have been subjected to fiber-opening treatment and glass woven fabrics that have been surface-treated with a silane coupling agent or the like. The thickness of the substrate is not particularly limited, but is preferably about 0.01 to 0.4 mm. Also, a prepreg can be obtained by impregnating reinforcing fibers with the varnish and drying the impregnated fibers by heating.

[0082] The laminate of this embodiment comprises one or more of the above prepregs. The laminate is not particularly limited as long as it comprises one or more prepregs, and may also comprise any other layer. The method for manufacturing the laminate can be any generally known method, and is not particularly limited. For example, when molding a metal foil-clad laminate, a multi-stage press, a multi-stage vacuum press, a continuous molding machine, an autoclave molding machine, or the like can be used. The prepregs are laminated together and then heated and pressure molded to obtain a laminate. The heating temperature is not particularly limited, but is preferably 65 to 300°C, and more preferably 120 to 270°C. The pressure applied is also not particularly limited, but if the pressure is too high, it becomes difficult to adjust the solid content of the resin in the laminate, resulting in unstable quality. If the pressure is too low, air bubbles will form and adhesion between the laminate layers will be poor. Therefore, a pressure of 2.0 to 5.0 MPa is preferred, and 2.5 to 4.0 MPa is more preferred. The laminate of this embodiment, having a layer made of metal foil, can be suitably used as a metal foil-clad laminate, as described below. The prepreg is cut into a desired shape and laminated with copper foil or the like as needed. The laminate is then heated and cured while applying pressure to the laminate by press molding, autoclave molding, sheet winding molding, or the like, to obtain an electrical and electronic laminate (printed wiring board) or a carbon fiber reinforced material.

[0083] The cured product of this embodiment can be used in various applications such as molding materials, adhesives, composite materials, paints, etc. The cured product of the curable resin composition described in this embodiment exhibits excellent heat resistance and dielectric properties, and is therefore suitable for use in electric and electronic parts such as encapsulants for semiconductor elements, encapsulants for liquid crystal display elements, encapsulants for organic EL elements, printed wiring boards, and build-up laminates, as well as composite materials for lightweight, high-strength structural materials such as carbon fiber reinforced plastics and glass fiber reinforced plastics.

[0084] The present invention will now be described in more detail with reference to examples. Unless otherwise specified, all parts are by weight. However, the present invention is not limited to these examples.

[0085] The various analytical methods used in the examples are described below. <Gel permeation chromatography (GPC)> Manufacturer: Shimadzu Corporation Column: Guard column SHODEX GPC KF-601 (2 columns), KF-602, KF-602.5, KF-603 (manufactured by Resonac Corporation) Flow rate: 1.5 ml / min. Column temperature: 40°C Solvent used: THF (tetrahydrofuran) Detector: RI (differential refractive index detector) <Gas chromatography mass spectrometry (GC-MS)> Gas chromatography mass spectrometer: Shimadzu Corporation GCMS-QP2010 Column: HP-5 (30 m) Carrier: Helium Flow rate: 1 mL / min Column temperature: 80°C (2 min) - 5°C / min - 300°C (60 min) Injection: autoinjector 1 μL, split 30:1, 300°C Ionization: EI

[0086] Example 1 1.00 part of dimethyl sulfoxide, 0.20 part of sodium hydroxide, 0.13 part of anthrone, and 0.30 parts of 4-chloromethylstyrene (AGC Seimi Chemical Co., Ltd., CMS-14) were charged into a vial and reacted at room temperature for 2 hours. The product was then analyzed by GC-MS. The presence of a peak at m / z = 310 confirmed that one molecule of p-methylstyrene had been added to anthrone by the dehydrochlorination reaction.

[0087] Examples 2 to 12, Comparative Examples 1 to 3 The same operation as in Example 1 was carried out, except that anthrone was replaced with various raw materials in the amounts shown in Table 1. The number of p-methylstyrenes added in the product is summarized in Table 1. In Table 1, an "O" in "Styrene 1 addition" indicates that one molecule of p-methylstyrene has been added, an "O" in "Styrene 2 addition" indicates that two molecules of p-methylstyrene have been added, and an "O" in "Styrene 3 addition" indicates that three molecules of p-methylstyrene have been added.

[0088] From the results in Table 1, it was confirmed that compounds with a pKa of less than 31 produced styrene compounds.

[0089] [Example 13] A flask equipped with a thermometer, a condenser, a stirrer, and a Dean-Stark azeotropic distillation trap was purged with nitrogen, and 83 parts of dimethyl sulfoxide, 83 parts of toluene, and 27 parts of a 30% aqueous sodium hydroxide solution were charged, and the mixture was heated to 120 ° C. to distill off water. After cooling to 40 ° C., a mixture of 12 parts of acetophenone and 29 parts of 4-chloromethylstyrene (AGC Seimi Chemical Co., Ltd., CMS-14) was added dropwise over 30 minutes, and the reaction was continued at 40 ° C. for 5 hours. After completion of the reaction, the mixture was diluted with 100 parts of toluene, and washed with water until the pH of the wastewater became neutral, and inorganic components were removed. The solvent was distilled off under heating and reduced pressure to obtain a crude product of the target compound. Thereafter, the mixture was diluted with 5 parts of toluene and washed with 100 parts of methanol, a poor solvent, to wash off the hydroxyl group-containing components derived from the 4-chloromethylstyrene hydrolyzate, and the solvent was again distilled off under heating and reduced pressure to obtain a yellow liquid target product (ST-1).

[0090] [Example 14] A flask equipped with a thermometer, a condenser, a stirrer, and a Dean-Stark azeotropic distillation trap was purged with nitrogen, and 81 parts of dimethyl sulfoxide, 81 parts of toluene, and 27 parts of a 30% aqueous sodium hydroxide solution were charged and heated to 120 ° C. to distill off water. After cooling to 40 ° C., a mixture of 10 parts of cyclohexanone and 29 parts of 4-chloromethylstyrene (AGC Seimi Chemical Co., Ltd., CMS-14) was added dropwise over 30 minutes, and the reaction was continued at 40 ° C. for 5 hours. After completion of the reaction, the mixture was diluted with 100 parts of toluene and washed with water until the pH of the wastewater became neutral, and inorganic components were removed. The solvent was distilled off under heating and reduced pressure to obtain a crude product of the target compound. Thereafter, the mixture was diluted with 5 parts of toluene and washed with 100 parts of methanol, a poor solvent, to wash off the hydroxyl group-containing components derived from the 4-chloromethylstyrene hydrolyzate, and the solvent was again distilled off under heating and reduced pressure to obtain a yellow liquid target product (ST-2).

[0091] [Example 15] A flask equipped with a thermometer, a condenser, and a stirrer was purged with nitrogen, and 100 parts of dimethyl sulfoxide, 12 parts of indene, and 49 parts of 4-chloromethylstyrene (AGC Seimi Chemical Co., Ltd., CMS-14) were charged and heated to 40 ° C with stirring. Thereafter, 12 parts of flaky sodium hydroxide were charged in portions over 12 hours, and the reaction was carried out at 40 ° C for 4 hours, 60 ° C for 3 hours, and 80 ° C for 4 hours. After completion of the reaction, the mixture was diluted with 100 parts of toluene, and washed with water until the pH of the wastewater became neutral, and inorganic components were removed. The solvent was distilled off under heating and reduced pressure to obtain a crude product of the target compound. Thereafter, the mixture was diluted with 16 parts of toluene and washed with 1,000 parts of methanol, a poor solvent, to wash and remove hydroxyl group-containing components derived from the 4-chloromethylstyrene hydrolyzate, and the solvent was again distilled off under heating and reduced pressure to obtain the target product (ST-3).

[0092] [Comparative Example 4] While purging nitrogen into a flask equipped with a thermometer, a condenser, and a stirrer, 200 parts of dimethyl sulfoxide, 33 parts of fluorene, and 24 parts of flaky sodium hydroxide were added and stirred at 35 ° C. for 30 minutes. Thereafter, 58 parts of 4-chloromethylstyrene (AGC Seimi Chemical Co., Ltd., CMS-14) were added dropwise over 1 hour while maintaining the internal temperature at 40 ° C. or less, and the mixture was allowed to react at 40 ° C. for 12 hours. 200 parts of methanol and 100 parts of water were added to cause crystallization, and the crystals were collected by filtration. The collected crystals were dissolved in 200 parts of toluene, and the organic layer was washed four times with 100 parts of water. The obtained organic layer was concentrated to obtain the target product (ST-4).

[0093] [Examples 16-18, Comparative Examples 5-7] The solvent solubility and storage stability of the curable resins (ST-1 to ST-4) obtained in Examples 13-15 and Comparative Example 4, as well as ST-5 and MI-1, described below, were examined. (Solvent Solubility) Each resin shown in Table 2 was diluted with toluene to a solids concentration of 30% or 50%, and whether or not it dissolved was confirmed. In the "Toluene Solubility" column in Table 2, resins that dissolved were marked with an ◯, and those that did not dissolve were marked with an X. (Storage Stability) Each resin shown in Table 2 was diluted with toluene to a solids concentration of 50% and left at room temperature for 5 days. The presence or absence of crystal precipitation was confirmed 1 day and 5 days after dilution. In the "Toluene Solution Stability" column in Table 2, resins that did not precipitate were marked with an ◯, and those that precipitated crystals were marked with an X.

[0094]

[0095] ST-5: OPE-2St 2200 (a polyphenylene ether compound having a styrene structure, manufactured by Mitsubishi Gas Chemical Company, Inc.) MI-1: bis(3-ethyl-5-methyl-4-maleimidophenyl)methane (manufactured by K.I. Chemical Co., Ltd., BMI-70)

[0096] From the results in Table 2, it was confirmed that Comparative Examples 5 and 7, which had an HSP distance of more than 2.5, had poor solubility in toluene and were difficult to use in combination with low-polarity materials. Since Comparative Example 4 was a polymer substance, the HSP distance could not be calculated.

[0097] [Examples 19-21, Comparative Examples 8-10] A 250 μm cushion paper frame with a 100 mm x 50 mm cutout in the center was placed on copper foil, and 5.0 g of a sample formulated according to the proportions shown in Table 3 was placed in the center of the frame. Another copper foil was placed on top of the frame and the sample, and the frame and sample were sandwiched between the two copper foils. The resulting product was molded in a vacuum heating press and cured at 220°C for 2 hours. The copper foil was then etched using ferric chloride to obtain a cured film. The heat resistance and dimensional stability of the cured film were measured using the methods described below.

[0098] <Heat Resistance and Dimensional Stability Test (TMA)> Thermomechanical analyzer: TMA Q400 (TA Instruments) Measurement temperature range: 30 to 350°C Heating rate: 2°C / min Sample size: Width 4 mm x Length 35 mm x Thickness 0.25 mm The linear expansion coefficient was measured while heating the sample using the thermomechanical analyzer. The temperature at which the linear expansion coefficient suddenly changed was taken as the glass transition temperature (TMA Tg). The measured glass transition temperatures (TMA Tg) are shown in Table 3. The average linear expansion coefficient from 60°C to 90°C (low-temperature linear expansion coefficient α1) and the average linear expansion coefficient from 260°C to 290°C (high-temperature linear expansion coefficient α2) are also shown in Table 3. Table 3 also shows the dimensional change of the sample size at 250°C (50-250°C dimensional change) based on the sample size at 50°C.

[0099]

[0100] Cat-1: 2-ethyl-4-methylimidazole

[0101] [Examples 22 and 23, Comparative Examples 11 to 13] A 250 μm cushion paper frame with a 100 mm x 50 mm cutout in the center was placed on copper foil, and 5.0 g of a sample formulated according to the proportions shown in Table 3 was placed in the center of the frame. Another copper foil was then placed on top of the frame and the sample. The frame and sample were sandwiched between the two sheets of copper foil, molded in a vacuum hot press, and cured at 220°C for 2 hours. The copper foil was then etched using ferric chloride to obtain a cured film. The dielectric properties of the cured film were measured using the method described below.

[0102] <Dielectric Property Test> The dielectric constant and dielectric loss tangent were measured at 25° C. by a cavity resonator perturbation method using a 10 GHz cavity resonator manufactured by AET Co., Ltd. The sample size was 1.7 mm wide x 100 mm long x 0.25 mm thick.

[0103]

[0104] From the results in Tables 2 to 4, it was confirmed that the curable resins of the present invention have excellent solvent solubility and dimensional stability, and further have low dielectric properties. On the other hand, ST-4 has issues with solvent solubility, ST-5 has issues with dimensional stability, and MI-1 has issues with solvent solubility and low-temperature linear expansion coefficient (α1).

[0105] The curable resin composition of the present invention and its cured product are useful for applications such as insulating materials for electric and electronic components (highly reliable semiconductor encapsulating materials, etc.), laminates (printed wiring boards, BGA substrates, build-up substrates, etc.), adhesives (conductive adhesives, etc.), various composite materials including CFRP, paints, and 3D printing.

Claims

1. A curable resin obtained by reacting a vinyl benzyl compound (A) represented by the following formula (1) with a compound (B) having a pKa of less than 31 in a dimethyl sulfoxide solvent, wherein the HSP distance to toluene is 2.5 or less, and the compound (B) is a compound having at least one of the substructures represented by the following formulas (2) to (5). 【Chemistry 1】 In equation (1), X represents a halogen atom. １ represents an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 6 to 20 carbon atoms which may have substituents, and s is an integer from 0 to 4. 【Chemistry 2】 In formula (2), Y2 represents an alkylene group, an -O- group, or an -C(=O)- group having 1 to 20 carbon atoms, which may have substituents. Each of the multiple R2s exists independently and represents an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 6 to 20 carbon atoms, which may have substituents. R2' represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 6 to 20 carbon atoms, which may have substituents. Each of the multiple s2s exists independently and is an integer from 0 to 4. The dotted line indicates that a bond may or may not exist. 【Transformation 3】 In formula (3), each of the multiple R3s exists independently and represents an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 6 to 20 carbon atoms which may have substituents, and s3 is an integer from 0 to 4. The dotted line indicates that a bond may or may not be present. 【Chemistry 4】 In formula (4), Y4 represents a C1-C10 alkylene group that is directly bonded or may have substituents. The multiple R4s exist independently of each other and represent an alkyl group having C1-C20 or an aromatic group having C6-C20 that may have substituents, and s4 is an integer from 0 to 10. The dotted line indicates that a bond may or may not be present. 【Transformation 5】 In formula (5), ring A represents a 7- or 8-membered aromatic ring. The multiple R5s exist independently of each other and represent an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 6 to 20 carbon atoms which may have substituents. s51 is an integer from 0 to 3, and s52 is 0 to the maximum number of substitutions.

2. A curable resin composition containing the curable resin described in claim 1.

3. The curable resin composition according to claim 2, further comprising at least one selected from the group consisting of maleimide 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, benzoxazine resin, epoxy resin, active ester compound, phenol resin, amine resin, isocyanate resin, polyamide resin, polyimide resin, and active ester.

4. Furthermore, the curable resin composition according to claim 2 contains a curing accelerator.

5. The curable resin composition according to claim 2, for use in printed circuit boards.

6. A varnish comprising the curable resin and organic solvent described in claim 1.

7. A varnish comprising the curable resin composition and organic solvent described in claim 2.

8. A cured product obtained by curing the curable resin described in claim 1.

9. A cured product obtained by curing the curable resin composition described in claim 2.

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