Phenol compound, polyphenylene ether, curable composition, cured product, electronic component, and compound

Abstract

To provide a technique related to a novel polyphenylene ether and to a novel monomer used for the synthesis of the polyphenylene ether.SOLUTION: One embodiment of the present invention is a phenol compound. This phenol compound is represented by chemical formula (1). In this chemical formula (1), R1 to R6 are each independently hydrogen or a C1-10 hydrocarbon group.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a phenolic compound, a polyphenylene ether, a curable composition, a cured product, an electronic component, and a compound. [Background technology]

[0002] With the spread of high-capacity, high-speed communications such as those represented by the fifth-generation communication system (5G) and millimeter-wave radar for automotive ADAS (Advanced Driver Assistance Systems), signals from communication devices are becoming increasingly high-frequency.

[0003] However, when epoxy resins and other materials are used as wiring board materials, the relative dielectric constant (Dk) and dielectric loss tangent (Df) are not low enough, so as the frequency increases, the transmission loss due to dielectric loss increases, causing problems such as signal attenuation and heat generation. For this reason, polyphenylene ether, which has excellent low dielectric properties, has been used.

[0004] Furthermore, Non-Patent Document 1 proposes polyphenylene ether having improved heat resistance by introducing an allyl group into the molecule of polyphenylene ether to make it a thermosetting resin. [Prior art documents] [Non-patent literature]

[0005] [Non-Patent Document 1] J. Nunoshige, H. Akahoshi, Y. Shibasaki, M. Ueda, J. Polym. Sci. Part A: Polym. Chem. 2008, 46, 5278-5282. Summary of the Invention [Problem to be solved by the invention]

[0006] Polyphenylene ethers are required to have various other properties in addition to low dielectric properties, and there is a demand for the development of new polyphenylene ethers that can satisfy these properties and new monomers that can be used in the synthesis of such polyphenylene ethers.

[0007] Therefore, an object of the present invention is to provide a novel polyphenylene ether and a novel monomer to be used in the synthesis of the polyphenylene ether. [Means for solving the problem]

[0008] One aspect of the present invention is a phenolic compound represented by the following chemical formula (1): JPEG2025006572000001.jpg46104In chemical formula (1), R1 to R6 are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0009] Another aspect of the present invention is a polyphenylene ether having a terminal structure represented by the following chemical formula (2). JPEG2025006572000002.jpg44114In chemical formula (2), R1 to R6 are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and "*" indicates a linking site. The polyphenylene ether of the above embodiment may have a branched structure.

[0010] Yet another aspect of the present invention is a compound, which is a precursor of the phenol compound of the above aspect and is represented by the following chemical formula (3). JPEG2025006572000003.jpg46126In chemical formula (3), R1 to R6 are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. Yet another aspect of the present invention is a precursor of the compound of the above aspect, which is represented by the following chemical formula (4): JPEG2025006572000004.jpg58120In chemical formula (4), R5 and R6 are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. Effect of the Invention

[0011] According to the present invention, it is possible to provide a technology relating to a novel polyphenylene ether and a novel monomer used in the synthesis of the polyphenylene ether. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 is a 1H-NMR (CDCl3, room temperature) spectrum of the compound represented by chemical formula II. [Diagram 2] FIG. 2 is a 1H-NMR (CDCl3, room temperature) spectrum of the compound represented by chemical formula III. [Diagram 3] FIG. 3 is the 1H-NMR (CDCl3, room temperature) spectrum of the phenolic compound represented by chemical formula IV. [Figure 4] FIG. 4 is a 1H-NMR (CDCl3, room temperature) spectrum of the polyphenylene ether according to Example 1. [Diagram 5] FIG. 5 is a 1H-NMR (CDCl3, room temperature) spectrum of the polyphenylene ether of Reference Example 1. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expression "a to b" in the explanation of a numerical range means that the range is from a to b, unless otherwise specified.

[0014] When the compounds described below have isomers, all possible isomers can be used in the present invention unless otherwise specified.

[0015] In this specification, phenols that are used as raw materials for polyphenylene ether (PPE) and can become structural units of polyphenylene ether are collectively referred to as "raw material phenols".

[0016] In this specification, when describing the raw material phenols, expressions such as "ortho position" and "para position" refer to the position of the phenolic hydroxyl group as the reference (ipso position), unless otherwise specified.

[0017] In this specification, when simply expressed as "ortho position" or the like, it means "at least one of the ortho positions", etc. Therefore, unless there is any particular contradiction, when simply expressed as "ortho position", it may be interpreted as indicating either one of the ortho positions, or it may be interpreted as indicating both ortho positions.

[0018] In this specification, the number average molecular weight (Mn) and weight average molecular weight (Mw) of polyphenylene ether are determined by gel permeation chromatography (GPC), using a Shodex K-805L column at a column temperature of 40° C., a flow rate of 1 mL / min, chloroform as the eluent, and polystyrene as the standard substance.

[0019] In this specification, when the upper limit and the lower limit of a numerical range are separately described, all combinations of the lower limit and the upper limit are substantially described, provided that there is no contradiction.

[0020] (Phenol compounds) The phenol compound according to the embodiment is represented by the following chemical formula (1). [ka] In the above chemical formula (1), R1 to R6 are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0021] Examples of the hydrocarbon group include an alkyl group, an alkenyl group, an alkynyl group, an aryl group, a cycloalkyl group, etc. When R1 to R6 are a hydrocarbon group, they are preferably linear or branched alkyl groups.

[0022] The phenol compound according to the embodiment can be synthesized according to the following reaction formulas (A) to (C). [ka] In the above reaction formulas (A) to (C), R1 to R6 are each independently hydrogen or a hydrocarbon group having 1 to 10 carbon atoms.

[0023] The reaction shown in reaction formula (A) is an addition reaction of a phenolic hydroxyl group of a raw material to a double bond of 3,4-dihydro-2H-pyran, more specifically, a tetrahydropyran protection reaction of the hydroxyl group. The reaction conditions can be appropriately selected from known conditions for an addition reaction of a phenolic hydroxyl group to a double bond. Specifically, an example of the reaction solvent is dichloromethane. An example of the reaction catalyst is pyridinium p-toluenesulfonate. The reaction shown in reaction formula (A) can proceed at room temperature.

[0024] The reaction shown in reaction formula (B) is a cross-coupling reaction between a compound represented by chemical formula (4) and a chloromethylstyrene derivative. The reaction conditions can be appropriately selected from known conditions for cross-coupling reactions. Specifically, the reaction can proceed under a nitrogen atmosphere at 100°C. Examples of reaction solvents include 2,4-dioxane, methanol, ethanol, toluene, tetrahydrofuran, dimethylformamide, water, and the like. Examples of bases include sodium hydrogen carbonate, sodium carbonate, potassium carbonate, and sodium hydroxide. Examples of reaction catalysts that can be used include palladium-based catalysts, such as palladium-tetrakis(triphenylphosphine).

[0025] The reaction shown in reaction formula (C) is a reaction for deprotecting the phenolic hydroxyl group of the compound represented by formula (3). The reaction conditions can be appropriately selected from known conditions for the deprotection reaction of a phenolic hydroxyl group. Specifically, for example, methanol can be used as the reaction solvent. In addition, p-toluenesulfonic acid monohydrate can be used as the reaction catalyst. The reaction shown in reaction formula (C) can proceed at room temperature.

[0026] <Uses of phenol compounds> The phenol compound according to the embodiment is a novel compound that can be used in various applications. One of the applications of the phenol compound according to the embodiment is as a monomer for constituting the terminal structure (terminal reactive group or terminal functional group) of a novel polyphenylene ether. By using a structure derived from the phenol compound according to the embodiment as a terminal structure of polyphenylene ether, excellent crosslinking reactivity can be imparted to the polyphenylene ether.

[0027] (First precursor of phenolic compounds) The first precursor of the phenol compound according to the embodiment (hereinafter simply referred to as "first precursor") is a precursor of the above-mentioned phenol compound. The first precursor is a novel compound represented by the following formula (3). [ka] In the above chemical formula (3), R1 to R6 are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0028] By using the first precursor as a starting material in the reaction of the above-mentioned reaction formula (C), a phenol compound represented by the above-mentioned chemical formula (1) and having the corresponding R1 to R6 can be synthesized.

[0029] (Second precursor of phenolic compounds) The second precursor of the phenolic compound of the embodiment (hereinafter simply referred to as the "second precursor") is a precursor of the above-mentioned phenolic compound and is also a precursor for synthesizing the above-mentioned first precursor. The second precursor is a novel compound represented by the following formula (4). [ka] In the above chemical formula (4), R5 and R6 are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

[0030] By using the second precursor as a starting material in the reaction of the above-mentioned reaction formula (B), the first precursor represented by the above-mentioned chemical formula (3) can be synthesized, and then, by going through the above-mentioned reaction formula (C), a phenol compound represented by the above-mentioned chemical formula (1) and having the corresponding R5 and R6 can be synthesized.

[0031] (Polyphenylene ether) The polyphenylene ether according to the embodiment has a terminal structure represented by the following chemical formula (2). [ka] In chemical formula (2), R1 to R6 are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and "*" indicates a linking site.

[0032] The polyphenylene ether according to the embodiment has a terminal structure represented by chemical formula (2), i.e., has a styryl group at the molecular chain terminal. The styryl group has a higher crosslinking reactivity than an allyl group, etc. Therefore, the polyphenylene ether having a styryl group at the molecular chain terminal has excellent crosslinking reactivity, and therefore the mechanical strength of the cured product can be improved.

[0033] The above-mentioned polyphenylene ether may have only a straight-chain structure, or may have a branched structure.

[0034] <Phenols, raw materials for polyphenylene ether> The raw material phenols for the polyphenylene ether according to the present embodiment (hereinafter also simply referred to as raw material phenols) contain at least the phenol compound represented by the above-mentioned chemical formula (1) (hereinafter may be referred to as phenol compound A). In addition, it is preferable that the raw material phenols further contain at least a phenol satisfying the following condition 1.

[0035] (Condition 1) Contains hydrogen atoms at the ortho and para positions

[0036] The raw material phenols may also contain other phenols.

[0037] Each phenol will be described below.

[0038] As the raw material phenols shown below, mainly monohydric phenols are disclosed, but polyhydric phenols may be used as the raw material phenols as long as they do not impair the effects of the present disclosure.

[0039] <Phenols that meet at least condition 1> Phenols that satisfy at least condition 1 have hydrogen atoms at the ortho and para positions.

[0040] Furthermore, the phenols satisfying at least the condition 1 may also include those satisfying the following condition 2.

[0041] (Condition 2) It has a hydrogen atom at the para position and a functional group containing an unsaturated carbon bond.

[0042] In addition, unless otherwise specified, the unsaturated carbon bond is an ethylenic or acetylenic carbon-carbon bond. It indicates a multiple bond (double bond or triple bond). The functional group containing an unsaturated carbon bond is not particularly limited, but includes an alkenyl group (e.g., a vinyl group, an allyl group), an alkynyl group (e.g., an ethynyl group), or a (meth)acryloyl group, and is preferably a hydrocarbon group containing an unsaturated carbon bond.

[0043] That is, the phenols satisfying at least condition 1 may be either (1) phenols that satisfy only condition 1 but do not satisfy condition 2, or (2) phenols that satisfy both conditions 1 and 2, and the raw material phenols may contain both of these phenols.

[0044] Phenols satisfying condition 1 also have a hydrogen atom at the ortho position. Therefore, when they are oxidatively polymerized with phenols, ether bonds can be formed not only at the ipso and para positions but also at the ortho position. Therefore, polyphenylene ether obtained by using such phenols as raw material phenols can form a branched chain structure. More specifically, a polyphenylene ether obtained from a phenol satisfying condition 1 has a structure in which a part of the structure is branched by benzene rings ether-bonded at least at three positions, i.e., the ipso position, the ortho position, and the para position. Such polyphenylene ether having a branched structure in the skeleton is sometimes called a “branched polyphenylene ether.” The branched polyphenylene ether has excellent solubility in organic solvents.

[0045] Furthermore, since the phenols satisfying condition 2 have a functional group containing an unsaturated carbon bond, the polyphenylene ether obtained by using such a phenol as a raw material phenol has a functional group containing an ethylenic or acetylenic carbon-carbon multiple bond. More specifically, a polyphenylene ether obtained from a phenol satisfying condition 2 has, as a part of its structure, a functional group containing an unsaturated carbon bond at least at the meta position or at either of two ortho positions of the benzene ring.

[0046] Examples of phenols that satisfy only condition 1 but not condition 2 include phenol, o-cresol, m-cresol, o-ethylphenol, m-ethylphenol, 2,3-xylenol, 2,5-xylenol, 3,5-xylenol, o-tert-butylphenol, m-tert-butylphenol, o-phenylphenol, m-phenylphenol, 2-dodecylphenol, etc. As phenols that satisfy condition 1, only one type may be used, or two or more types may be used.

[0047] Examples of phenols satisfying both the condition 1 and the condition 2 include o-vinylphenol, m-vinylphenol, o-allylphenol, m-allylphenol, 3-vinyl-6-methylphenol, 3-vinyl-6-ethylphenol, 3-vinyl-5-methylphenol, 3-vinyl-5-ethylphenol, 3-allyl-6-methylphenol, 3-allyl-6-ethylphenol, 3-allyl-5-methylphenol, 3-allyl-5-ethylphenol, etc. As the phenols satisfying the condition 1 and the condition 2, only one kind may be used, or two or more kinds may be used.

[0048] In the synthesis of polyphenylene ether, the content of phenols satisfying at least condition 1 relative to the total amount of raw material phenols is preferably 1 mol% or more, 2 mol% or more, 3 mol% or more, or 5 mol% or more, and is preferably 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, or 15 mol% or less.

[0049] In the synthesis of polyphenylene ether, the content of phenol compound A relative to the total amount of raw material phenols is preferably 1 mol% or more, 2 mol% or more, 3 mol% or more, or 5 mol% or more, and is preferably 50 mol% or less, 40 mol% or less, 30 mol% or less, 20 mol% or less, or 15 mol% or less.

[0050] The ratio of the content (mol %) of phenol compound A to the content (mol %) of phenols satisfying condition 1, based on the total amount of raw material phenols (phenol compound A / phenols satisfying condition 1), is preferably 0.1 to 10.0, 0.2 to 5.0, or 0.5 to 2.0.

[0051] By using, as the raw material phenols, phenols that satisfy at least the condition 1, it is possible to synthesize polyphenylene ether having a branched structure. On the other hand, by not using phenols that satisfy at least the condition 1, it is possible to synthesize polyphenylene ether having a linear structure.

[0052] <Other phenols> The other phenols are phenols that do not satisfy condition 1 and do not fall under phenol compound A.

[0053] Examples of other phenols include (1) phenols that do not satisfy condition 1, satisfy condition 2, and do not fall under phenolic compound A, and (2) phenols that do not satisfy either condition 1 or condition 2, and do not fall under phenolic compound A.

[0054] Phenols that do not satisfy condition 1, but do satisfy condition 2, and do not fall under the category of phenolic compound A, are, for example, phenols that have a hydrogen atom at the para position and hydrocarbon groups at both ortho positions, at least one of which has a functional group containing an unsaturated carbon bond. Examples of such phenols include 2-allyl-6-methylphenol, 2-allyl-6-ethylphenol, 2-allyl-6-phenylphenol, 2-allyl-6-styrylphenol, 2,6-divinylphenol, 2,6-diallylphenol, 2,6-diisopropenylphenol, 2,6-dibutenylphenol, 2,6-diisobutenylphenol, 2,6-diisopentenylphenol, 2-methyl-6-styrylphenol, 2-vinyl-6-methylphenol, and 2-vinyl-6-ethylphenol.

[0055] Phenols that do not satisfy either condition 1 or condition 2 and do not fall under the category of phenolic compound A include, for example, phenols that have a hydrogen atom at the para position and a hydrocarbon group that does not contain an unsaturated carbon bond at any ortho position. Examples of such phenols include 2,6-dimethylphenol, 2,3,6-trimethylphenol, 2-methyl-6-ethylphenol, 2-ethyl-6-n-propylphenol, 2-methyl-6-n-butylphenol, 2-methyl-6-phenylphenol, 2,6-diphenylphenol, and 2,6-ditolylphenol.

[0056] In this way, when a phenol having a hydrogen atom at the para position is used as the other phenol, ether bonds are formed at the ipso and para positions of the benzene ring and polymerized into a linear chain, which is useful for adjusting the proportion of branched structures and also makes it easier to adjust the molecular weight of the polyphenylene ether.

[0057] In addition, examples of phenols that do not satisfy either condition 1 or condition 2 and do not fall under phenol compound A include phenols that do not have hydrogen atoms at the para and ortho positions and do not have a functional group containing an unsaturated carbon bond. In this way, when a phenol having no hydrogen atoms at either the para- or ortho-position is used as the other phenol, the polymerization reaction of polyphenylene ether is suppressed, making it easier to adjust the molecular weight of the polyphenylene ether.

[0058] The other phenols may be used alone or in combination of two or more.

[0059] In the synthesis of polyphenylene ether, the content of other phenols relative to the total amount of raw material phenols is, for example, 10 mol % or more, 20 mol % or more, 30 mol % or more, 40 mol % or more, or 50 mol % or more.

[0060] <Production method of polyphenylene ether> The polyphenylene ether of the present embodiment can be produced by a known polyphenylene ether synthesis method, except that the raw material phenols and the ratio of the raw material phenols used are as described above. For example, it can be produced by the synthesis method disclosed in International Publication WO2020 / 017570.

[0061] <Physical properties of polyphenylene ether> The weight average molecular weight of the polyphenylene ether is preferably from 5,000 to 80,000, more preferably from 8,000 to 60,000, and even more preferably from 10,000 to 40,000. The number average molecular weight of the polyphenylene ether is preferably from 5,000 to 20,000, and more preferably from 8,000 to 18,000.

[0062] The molecular weight of the polyphenylene ether can be adjusted by changing the reaction temperature, reaction time, etc. during synthesis, although this depends on the type of raw material phenol used. The polyphenylene ether of the present embodiment has excellent dielectric properties. As described above, the polyphenylene ether of the present embodiment has a terminal structure having a styryl group derived from the phenol compound A, and therefore has excellent crosslinking reactivity and therefore excellent mechanical strength.

[0063] (Curable composition) The curable composition includes the polyphenylene ether according to this embodiment. The curable composition may also contain other components.

[0064] The content of the polyphenylene ether in the curable composition is preferably 50 to 90 mass %, more preferably 60 to 80 mass %, based on the total amount excluding volatile components and inorganic fillers in the curable composition.

[0065] Examples of other components include additives such as inorganic fillers such as silica, peroxides, crosslinking curing agents, polyphenylene ethers other than the polyphenylene ether according to this embodiment, polymerization initiators, maleimide resins, resin and polymer components such as styrene-based elastomers, sensitizers, adhesion aids, surfactants, leveling agents, plasticizers, adhesion agents, colorants, fibers, silane coupling agents, flame retardants, cellulose nanofibers, dispersants, thermosetting catalysts, thickeners, defoamers, antioxidants, rust inhibitors, and adhesion imparting agents.

[0066] Other components may be appropriately selected depending on the application. For example, when the curable composition contains a peroxide, the crosslinking reaction of the curable composition is promoted, and various physical properties of the cured product are likely to be improved. In addition, when the curable composition contains a crosslinking curing agent, the low dielectric properties and heat resistance of the cured product are likely to be improved.

[0067] Peroxides include methyl ethyl ketone peroxide, methyl acetoacetate peroxide, acetylacetonate peroxide, 1,1-bis(t-butylperoxy)cyclohexane, 2,2-bis(t-butylperoxy)butane, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, di-t-butyl hydroperoxide, t-butyl hydroperoxide, dicumyl peroxide, 2,5-di Examples of the peroxide include methyl-2,5-di(t-butylperoxy)hexane, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne, 2,5-dimethyl-2,5-di(t-butylperoxy)-3-butene, acetyl peroxide, octanoyl peroxide, lauroyl peroxide, benzoyl peroxide, m-toluyl peroxide, diisopropyl peroxydicarbonate, t-butylene peroxybenzoate, di-t-butyl peroxide, t-butylperoxyisopropyl monocarbonate, α,α'-bis(t-butylperoxy-m-isopropyl)benzene, etc. Only one type of peroxide may be used, or two or more types may be used.

[0068] The content of the peroxide in the curable composition is preferably 0.1 to 10 parts by mass, and more preferably 1 to 5 parts by mass, based on 100 parts by mass of the polyphenylene ether content in the curable composition.

[0069] Examples of the crosslinking curing agent include polyfunctional vinyl compounds such as divinylbenzene, divinylnaphthalene, and divinylbiphenyl; vinylbenzyl ether compounds synthesized by the reaction of phenol with vinylbenzyl chloride; styrene monomers such as diallyl phthalate and diallyl isophthalate, and allyl ether compounds synthesized by the reaction of phenol with allyl chloride; and further, trialkenyl isocyanurates such as triallyl isocyanurate (hereinafter, TAIC (registered trademark)) and triallyl cyanurate. Among them, triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, and diallyl isophthalate, which have particularly good compatibility with polyphenylene ether, are preferred. Only one type of crosslinking curing agent may be used, or two or more types may be used.

[0070] The content of the crosslinking curing agent in the curable composition is preferably 1 to 100 parts by mass, and more preferably 10 to 80 parts by mass, based on 100 parts by mass of the polyphenylene ether content in the curable composition.

[0071] The curable composition may also be in the form of a varnish containing a solvent. As the solvent, a solvent capable of dissolving the above-mentioned polyphenylene ether is preferred, and in addition to conventionally usable solvents such as chloroform, methylene chloride, and toluene, preferred solvents include N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), cyclohexanone, propylene glycol monomethyl ether acetate (PMA), diethylene glycol monoethyl ether acetate (CA), methyl ethyl ketone, ethyl acetate, etc. These may be used alone or in combination of two or more.

[0072] (Dry film, prepreg) The dry film has a resin layer made of the curable composition of the present disclosure on a carrier film (support film). The dry film is used by laminating the resin layer so as to be in contact with a substrate.

[0073] The dry film can be produced by uniformly applying the curable composition onto a carrier film by an appropriate method such as a blade coater, lip coater, comma coater, or film coater, drying the composition to form the above-mentioned resin layer, and preferably laminating a cover film (protective film) thereon. The cover film and the carrier film may be made of the same film material or different films.

[0074] The film materials for the carrier film and the cover film may be any of those known to be used for dry films.

[0075] As the carrier film, for example, a thermoplastic film such as a polyester film, eg, polyethylene terephthalate, having a thickness of 2 to 150 μm is used.

[0076] The cover film may be a polyethylene film, a polypropylene film, or the like, but it is preferable that the adhesive strength with the resin layer is smaller than that of the carrier film.

[0077] The thickness of the resin layer on the dry film is preferably 100 μm or less, and more preferably in the range of 5 to 50 μm.

[0078] The prepreg can be obtained, for example, by impregnating a substrate such as glass cloth with a curable composition and drying it.

[0079] (cured product) A cured product can be produced by using the curable composition or a dry film having a resin layer made of the curable composition.

[0080] The method for obtaining a cured product from the curable composition is not particularly limited, and can be appropriately changed depending on the composition of the curable composition.

[0081] For example, the cured product can be formed by the following method. After the curable composition is applied to the substrate as described above (for example, by using an applicator), a drying step is performed to dry the curable composition as necessary to form a resin layer on the substrate, or a dry film is laminated on the substrate to transfer the resin layer made of the curable composition. Next, a thermal curing step is carried out in which the polyphenylene ether is thermally crosslinked by heating (for example, heating with an inert gas oven, a hot plate, a vacuum oven, a vacuum press machine, or the like) to cure the resin layer.

[0082] The conditions for carrying out each step (for example, coating thickness, drying temperature and time, heating temperature and time, etc.) may be appropriately changed depending on the composition and application of the curable composition.

[0083] (Electronic Components) The electronic component has the cured product of the present disclosure described above. Since the cured product of the present disclosure has excellent dielectric properties and heat resistance, it can be used for various applications as a material for constituting electronic components.

[0084] Its applications are not particularly limited, but preferred examples include insulating materials in electronic components such as large-capacity, high-speed communications typified by the fifth-generation communication system (5G) and millimeter-wave radars for automotive ADAS (advanced driving systems).

[0085] Although the embodiments of the present invention have been described above, these are merely examples of the present invention, and various configurations other than those described above can also be adopted. EXAMPLES

[0086] The present invention will be described below with reference to examples and reference examples, but the present invention is not limited to these.

[0087] (Synthesis of phenolic compounds) In a 100 mL two-neck flask, 2,6-dimethylphenol-4-boronic acid pinacol ester (2.97 g, 0.0120 mol) represented by chemical formula I, 3,4-dihydro-2H-pyran (1.56 g, 0.0186 mol), pyridinium p-toluenesulfonate (0.301 g, 0.00120 mol), and dichloromethane (40 mL) were added. The atmosphere was replaced with nitrogen and the mixture was stirred at room temperature for 21 hours. The reaction solution was extracted with 1% sodium carbonate aqueous solution (100 mL) and purified by silica gel chromatography (ethyl acetate:heptane = 1:4), obtaining the target colorless transparent oil (compound represented by chemical formula II) (2.55 g, 0.00767 mol) in a yield of 64%. Figure 1 shows the compound represented by chemical formula II. 1 H-NMR (CDCl3, room temperature) spectrum is shown.

[0088] In a 100 mL two-neck flask, the compound represented by chemical formula II (2.020 g, 0.00627 mol), chloromethylstyrene (1.388 g, 0.009093 mol), Pd(PPh3)4 (0.108 g, 0.0000936 mol), 1,4-dioxane (40 mL), and 2 M sodium carbonate aqueous solution (4.5 mL) were added and replaced with nitrogen. The mixture was heated and stirred at 90°C for 24 hours, and the completion of the reaction was confirmed by TLC. The obtained product was purified by silica gel chromatography (ethyl acetate:heptane = 1:6) to obtain 3 (0.947 g, 0.00294 mol) as a colorless, transparent oil in a yield of 47%. Figure 2 shows the compound represented by chemical formula III. 1 H-NMR (CDCl3, room temperature) spectrum is shown.

[0089] The compound represented by chemical formula III (1.471 g, 0.004560 mol), p-toluenesulfonic acid monohydrate (0.088 g, 0.00047 mol), and dichloromethane (40 mL) were added to a 100 mL recovery flask and stirred at room temperature for 5 hours. The completion of the reaction was confirmed by TLC. The mixture was extracted with water (100 mL) and dried, after which the organic solvent was distilled off. The resulting brown oil (0.652 g) was purified by silica gel chromatography (ethyl acetate:heptane=1:3). By distilling off the organic solvent, 2,6-dimethyl-4-(4-vinylbenzyl)phenol (0.975 g, 0.00409 mol) was obtained as a pale yellow oily product (phenolic compound represented by chemical formula IV) with a yield of 90%. Figure 3 shows the phenolic compound represented by chemical formula IV. 1 H-NMR (CDCl3, room temperature) spectrum is shown. [ka]

[0090] (Synthesis of polyphenylene ether) Example 1 As raw material phenols, 2,6-dimethylphenol, 2-allylphenol, and a phenol compound represented by chemical formula IV were used. A 100mL two-neck flask was used as a reaction vessel, and 3.61g (80mol%) of 2,6-dimethylphenol, 0.507g (10mol%) of 2-allylphenol, and 0.882g (10mol%) of a phenolic compound represented by chemical formula IV were dissolved in 28.92g of toluene to prepare a raw material solution. In addition, 0.119g of di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) and 0.131g of tetramethylethylenediamine (TMEDA) were adjusted, and the reaction solution was stirred at a stirring speed of 350 rpm while blowing dry air into the reaction solution at a flow rate of 17mL / min, and reacted at 40°C for 15 hours to obtain a reaction solution containing polyphenylene ether. After stopping the heating of the reaction solution and the blowing of dry air, di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) was removed by filtration, and reprecipitated in a mixture of 1,200 mL of methanol, 4.0 mL of concentrated hydrochloric acid, and 7.0 mL of H2O2, filtered under reduced pressure, washed with methanol, and dried at 80°C for 24 hours to obtain polyphenylene ether according to Example 1. FIG. 4 shows the structure of polyphenylene ether according to Example 1. 1 H-NMR (CDCl3, room temperature) spectrum is shown.

[0091] [Table 1]

[0092] (Reference example 1) A polyphenylene ether according to Reference Example 1 was obtained in the same manner as in Example 1, except that 2,6-dimethylphenol and 2-allylphenol were used as raw material phenols and the production conditions were as shown in Table 1. FIG. 1 H-NMR (CDCl3, room temperature) spectrum is shown.

[0093] <Molecular weight> The weight average molecular weight (M w ) and number average molecular weight (M n ) was measured. w and M. n The measurement results are shown in Table 1. <Number of terminal reactive groups per number average molecular weight> First, for each sample 1 The polymerization ratio of each raw material phenol is calculated from the results of H-NMR measurement, and the theoretical value of the styryl group equivalent is calculated from the polymerization ratio X of the repeating unit derived from each raw material phenol when the unit derived from the styryl group is set to 1, using the following formula.

number

[0094] (evaluation) By adjusting the synthesis conditions (reaction time, etc.), a polyphenylene ether according to Reference Example 2 having the same monomer composition as Reference Example 1 and a weight average molecular weight of 54,400 was obtained. The polyphenylene ether according to Example 1 and the polyphenylene ether according to Reference Example 2 were evaluated for dielectric constant and tensile properties.

[0095] <Production of cured film> A resin composition was prepared by mixing 100 parts by mass of each polyphenylene ether, 50 parts by mass of a cross-linking curing agent (product name "TAIC", manufactured by Mitsubishi Chemical Corporation), 5 parts by mass of a peroxide (product name "Perbutyl P40", manufactured by NOF Corporation), and 350 parts by mass of cyclohexanone (solvent). Each resin composition was applied to the shine side of 18 μm thick copper foil so that the film thickness after drying was about 20 μm, and then dried in a hot air circulation drying oven at 90 ° C for 30 minutes. Then, it was cured in an inert oven at 200 ° C for 1 hour, and the copper foil was etched to obtain a cured film (measurement sample).

[0096] <Dielectric constant> (Measurement method) The measurement sample was cut into a length of 80 mm and a width of 45 mm to be used as a test piece, and the relative dielectric constant Dk and dielectric loss tangent Df were measured by the SPDR (Split Post Dielectric Resonator) resonator method. The measuring equipment used was a vector network analyzer E5071C manufactured by Keysight Technologies, LLC, an SPDR resonator, and a calculation program manufactured by QWED. The conditions were a frequency of 10 GHz and a measurement temperature of 25°C.

[0097] (Measurement results) The cured product obtained using the polyphenylene ether of Example 1 had Dk and Df of 2.7 and 0.0026, respectively. The cured product obtained using the polyphenylene ether of Reference Example 2 had Dk and Df of 2.7 and 0.0025. The above results demonstrate that low dielectric properties can be maintained even when the phenol compound represented by chemical formula IV is used as the raw material phenol for polyphenylene ether having a branched structure.

[0098] <Tensile properties> (Measurement method) The measurement sample was cut to a length of 8 cm and a width of 0.5 cm, and the breaking elongation (tensile breaking elongation) and tensile strength (tensile breaking strength) were measured under the following conditions. The elastic modulus was determined from the slope of the strain at stresses of 5 MPa to 10 MPa in the obtained stress-strain curve. [Measurement conditions] Testing machine: Tensile testing machine EZ-SX (manufactured by Shimadzu Corporation) Chuck distance: 50mm Test speed: 1mm / min Elongation calculation: (tensile travel distance / chuck distance) x 100

[0099] (Measurement results) The cured product obtained using the polyphenylene ether of Example 1 had an elastic modulus of 2.8 GPa, a breaking elongation of 5.2%, and a tensile strength of 86 MPa. In contrast, the cured product obtained using the polyphenylene ether of Reference Example 2 had an elastic modulus of 2.5 GPa, an elongation at break of 3.5%, and a tensile strength of 81 MPa. The above results show that the use of the phenol compound represented by chemical formula IV as a raw phenol for polyphenylene ether having a branched structure makes it possible to improve mechanical strength, particularly elongation at break.

Claims

1. A phenol compound represented by the following chemical formula (1): 【Chemistry 1】 In the chemical formula (1), R １ ~R ６ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

2. A polyphenylene ether having a terminal structure represented by the following chemical formula (2): 【Chemistry 2】 In the chemical formula (2), R １ ~R ６ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and "*" indicates a linking site.

3. The polyphenylene ether according to claim 2, which has a branched structure.

4. A curable composition comprising the polyphenylene ether according to claim 2 or 3.

5. A cured product of the curable composition according to claim 4.

6. An electronic component comprising the cured product according to claim 5 .

7. A compound which is a precursor of the phenol compound according to claim 1 and is represented by the following chemical formula (3): 【Chemistry 3】 In the chemical formula (3), R １ ~R ６ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

8. A compound which is a precursor of the compound according to claim 7 and is represented by the following chemical formula (4): 【Chemistry 4】 In the chemical formula (4), R ５ , R ６ are each independently a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.

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