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

Abstract

Provided is a technique related to a novel polyphenylene ether and to a novel monomer used for the synthesis of this polyphenylene ether.　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.

Description

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

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

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

[0003] However, when epoxy resins and other materials are used as wiring board materials, the dielectric constant (Dk) and dielectric loss tangent (Df) are not sufficiently low, so as the frequency increases, 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 with improved heat resistance, which is made into a thermosetting resin by introducing an allyl group into the molecule of polyphenylene ether.

[0005] J. Nunoshige, H. Akahoshi, Y. Shibasaki, M. Ueda, J. Polym. Sci. Part A: Polym. Chem. 2008, 46, 5278-5282.

[0006] Polyphenylene ethers are required to have various properties in addition to low dielectric properties, and there is a need to develop new polyphenylene ethers that can satisfy these properties and new monomers that can be used to synthesize 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 synthesizing the polyphenylene ether.

[0008] One aspect of the present invention is a phenolic compound represented by the following chemical formula (1): In the chemical formula (1), R １ ~R６ are each independently hydrogen 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): In chemical formula (2), R １ ~R ６ are each independently hydrogen 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 first aspect and is represented by the following chemical formula (3): In chemical formula (3), R １ ~R ６ are each independently hydrogen or a hydrocarbon group having 1 to 10 carbon atoms. A further aspect of the present invention is a precursor of the compound of the above-mentioned aspect. The precursor is represented by the following chemical formula (4): In chemical formula (4), R ５ , R ６ are each independently hydrogen or a hydrocarbon group having 1 to 10 carbon atoms.

[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 synthesizing the polyphenylene ether.

[0012] FIG. 1 is a diagram of a compound represented by formula II. １ H-NMR (CDCl ３ 2 shows the spectrum of the compound represented by formula III. １ H-NMR (CDCl ３ 3 shows the spectra of the phenolic compound represented by formula IV. １ H-NMR (CDCl ３ 4 shows the spectrum of the polyphenylene ether of Example 1. １ H-NMR (CDCl ３ 5 shows the spectrum of the polyphenylene ether of Reference Example 1.１ H-NMR (CDCl ３ , room temperature) spectrum.

[0013] Hereinafter, embodiments of the present invention will be described in detail. In this specification, the expression "a to b" in the description of a range of values ​​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 a particular contradiction occurs, when simply expressed as "ortho position", it may be interpreted as indicating either one of the ortho positions or 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.

[0019] In this specification, when the upper and lower limits of a numerical range are separately stated, all combinations of each lower limit and each upper limit are considered to be substantially stated within a consistent range.

[0020] (Phenol Compound) The phenol compound according to the embodiment is represented by the following chemical formula (1). In the above chemical formula (1), R１ ~R ６ are each independently hydrogen 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, and a cycloalkyl group. １ ~R ６ When is a hydrocarbon group, it is preferably a linear or branched alkyl group.

[0022] The phenol compound according to the embodiment can be synthesized according to the following reaction formulas (A) to (C). R represented by the above reaction formulas (A) to (C) １ ~R ６ 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 in a raw material to a double bond in 3,4-dihydro-2H-pyran, more specifically, a protection reaction of the hydroxyl group with tetrahydropyran. 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 a reaction solvent is dichloromethane. An example of a 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, for example, under a nitrogen atmosphere at 100°C. Examples of reaction solvents include 2,4-dioxane, methanol, ethanol, toluene, tetrahydrofuran, dimethylformamide, and water. Examples of bases include sodium bicarbonate, sodium carbonate, potassium carbonate, and sodium hydroxide. A palladium-based catalyst can be used as the reaction catalyst, such as palladium-tetrakis(triphenylphosphine).

[0025] The reaction represented by 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 deprotecting a phenolic hydroxyl group. Specifically, for example, methanol can be used as the reaction solvent. Furthermore, p-toluenesulfonic acid monohydrate can be used as the reaction catalyst. The reaction represented by reaction formula (C) can proceed at room temperature.

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

[0027] (First Precursor of Phenolic Compound) The first precursor of the phenolic compound according to the embodiment (hereinafter simply referred to as "first precursor") is a precursor of the phenolic compound described above. The first precursor is a novel compound represented by the following formula (3). In the above chemical formula (3), R １ ~R ６ are each independently hydrogen or a hydrocarbon group having 1 to 10 carbon atoms.

[0028] The first precursor is used as a starting material in the reaction of the above-mentioned reaction formula (C), and the corresponding R １ ~R ６ It is possible to synthesize a phenolic compound having the following structure:

[0029] (Second Precursor of Phenolic Compound) The second precursor of the phenolic compound according to the embodiment (hereinafter simply referred to as "second precursor") is a precursor of the above-described phenolic compound and also a precursor for synthesizing the above-described first precursor. The second precursor is a novel compound represented by the following formula (4): In the above chemical formula (4), R ５ , R ６ are each independently hydrogen 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 by going through the above-mentioned reaction formula (C), the first precursor represented by the above-mentioned chemical formula (1) and the corresponding R ５ , R ６ It is possible to synthesize a phenolic compound having the following structure:

[0031] (Polyphenylene Ether) The polyphenylene ether according to the embodiment has a terminal structure represented by the following chemical formula (2). In chemical formula (2), R １ ~R ６ are each independently hydrogen 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 higher cross-linking reactivity than an allyl group or the like. Therefore, the polyphenylene ether having a styryl group at the molecular chain terminal has excellent cross-linking reactivity, and therefore, when formed into a cured product, the mechanical strength can be improved.

[0033] The polyphenylene ether may have only a linear structure or may have a branched structure.

[0034] <Raw Material Phenols for Polyphenylene Ether> The raw material phenols for the polyphenylene ether according to this embodiment (hereinafter also simply referred to as raw material phenols) contain at least a phenol compound represented by the above-described chemical formula (1) (hereinafter also referred to as phenol compound A). In addition, it is preferable that the raw material phenols further contain a phenol that satisfies at least the following condition 1:

[0035] (Condition 1) Having 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] Although monohydric phenols are mainly disclosed as the raw material phenols shown below, polyhydric phenols may also be used as the raw material phenols as long as they do not impair the effects of the present disclosure.

[0039] <Phenols Satisfying at Least Requirement 1> Phenols satisfying at least Requirement 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) Having a hydrogen atom at the para position and a functional group containing an unsaturated carbon bond

[0042] Unless otherwise specified, the unsaturated carbon bond refers to an ethylenic or acetylenic carbon-carbon multiple bond (double bond or triple bond). The functional group containing an unsaturated carbon bond is not particularly limited, but examples thereof include an alkenyl group (e.g., a vinyl group or 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 not 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 hydrogen atoms at the ortho position, and therefore, when 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 ethers obtained using such phenols as raw material phenols can form a branched-chain structure. More specifically, polyphenylene ethers obtained from phenols satisfying condition 1 have a structure in which a portion of the structure is branched by ether-bonded benzene rings at at least three positions: the ipso, ortho, and para positions. Thus, polyphenylene ethers having a branched structure within the skeleton are sometimes referred to as branched-structure polyphenylene ethers. Branched-structure polyphenylene ethers exhibit excellent solubility in organic solvents.

[0045] Furthermore, since phenols satisfying condition 2 have a functional group containing an unsaturated carbon bond, polyphenylene ether obtained by using such phenols as raw material phenols has a functional group containing an ethylenic or acetylenic carbon-carbon multiple bond. More specifically, polyphenylene ether obtained from phenols satisfying condition 2 has, as part of its structure, a functional group containing an unsaturated carbon bond at least at the meta position or one 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 conditions 1 and 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 phenols satisfying conditions 1 and 2, only one type may be used, or two or more types may be used.

[0048] In the synthesis of polyphenylene ether, the content of phenols that satisfy 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] It should be noted that polyphenylene ether having a branched structure can be synthesized by using, as the raw material phenols, phenols that satisfy at least the condition 1. On the other hand, by not using phenols that satisfy at least the condition 1, polyphenylene ether having a linear structure can be synthesized.

[0052] <Other Phenols> Other phenols are phenols that do not satisfy condition 1 and do not fall under the category of 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, 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 are, 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 either 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, resulting in linear polymerization, 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] Furthermore, examples of phenols that do not satisfy either condition 1 or condition 2 and do not fall under the category of phenol compound A include phenols that have no hydrogen atoms at the para- and ortho-positions and have no functional group containing an unsaturated carbon bond. When a phenol that has 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] <Method for Producing Polyphenylene Ether> The polyphenylene ether of the present embodiment can be produced by a known method for synthesizing polyphenylene ether, 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 WO 2020 / 017570.

[0061] <Physical Properties / Characteristics of Polyphenylene Ether> The weight-average molecular weight of the polyphenylene ether is preferably 5,000 to 80,000, more preferably 8,000 to 60,000, and even more preferably 10,000 to 40,000. The number-average molecular weight of the polyphenylene ether is preferably 5,000 to 20,000, and even more preferably 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, depending on the type of raw material phenol used. The polyphenylene ether of this embodiment has excellent dielectric properties. Furthermore, as described above, the polyphenylene ether of this embodiment has excellent crosslinking reactivity due to the presence of a styryl group derived from phenol compound A as a terminal structure, and therefore also has excellent mechanical strength.

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

[0064] The content of 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 inorganic fillers such as silica, peroxides, crosslinking curing agents, polyphenylene ethers other than the polyphenylene ether according to the present embodiment, polymerization initiators, resin and polymer components such as maleimide resins and 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, antifoaming agents, antioxidants, rust inhibitors, and adhesion promoters.

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

[0067] Examples of peroxides include methyl ethyl ketone peroxide, methyl acetoacetate peroxide, acetylacetonperoxide, 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 peroxides 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, relative to 100 parts by mass of the polyphenylene ether content in the curable composition.

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

[0070] The content of the cross-linking curing agent in the curable composition is preferably 1 to 100 parts by mass, and more preferably 10 to 80 parts by mass, relative to 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. The solvent is preferably one capable of dissolving the polyphenylene ether described above. Examples of the solvent include conventionally usable solvents such as chloroform, methylene chloride, and toluene, as well as N-methyl-2-pyrrolidone (NMP), tetrahydrofuran (THF), cyclohexanone, propylene glycol monomethyl ether acetate (PMA), diethylene glycol monoethyl ether acetate (CA), methyl ethyl ketone, and ethyl acetate. These may be used alone or in combination of two or more.

[0072] (Dry Film, Prepreg) A 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 that it is 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 resin layer described above, 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 made of polyethylene terephthalate or the like 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 weaker than that of the carrier film.

[0077] The thickness of the resin layer on the dry film is preferably 100 μm or less, 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 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, a cured product can be formed by the following method. After applying the curable composition to a substrate as described above (for example, by applying using an applicator, etc.), a drying step is carried out to dry the curable composition as needed, thereby forming a resin layer on the substrate. Alternatively, a dry film is laminated onto the substrate, and a resin layer made of the curable composition is transferred. Next, a thermal curing step is carried out to thermally crosslink the polyphenylene ether by heating (for example, by heating using an inert gas oven, a hot plate, a vacuum oven, a vacuum press, etc.), thereby curing 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 Component) An electronic component has the cured product of the present disclosure described above. The cured product of the present disclosure has excellent dielectric properties and heat resistance, and therefore can be used for various purposes as a material for constituting electronic components.

[0084] There are no particular limitations on the use of the material, but preferred examples include insulating materials in electronic components such as large-capacity, high-speed communications typified by fifth-generation communication systems (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 other configurations can also be adopted.

[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 Phenol Compound) 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 placed in a 100 mL two-neck flask. The atmosphere was replaced with nitrogen and the mixture was stirred at room temperature for 21 hours. The reaction solution was extracted with 1% aqueous sodium carbonate solution (100 mL) and purified by silica gel chromatography (ethyl acetate:heptane=1:4), yielding the target colorless, transparent oil (compound represented by chemical formula II) (2.55 g, 0.00767 mol) in a 64% yield. Figure 1 shows the structure of the compound represented by chemical formula II. １ H-NMR (CDCl ３ , room temperature) spectrum is shown.

[0088] In a 100 mL two-neck flask, the compound represented by formula II (2.020 g, 0.00627 mol), chloromethylstyrene (1.388 g, 0.009093 mol), Pd(PPh ３ ) ４ (0.108 g, 0.0000936 mol), 1,4-dioxane (40 mL), and 2M aqueous sodium carbonate 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 resulting 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 47% yield. Figure 2 shows the compound represented by chemical formula III. １ H-NMR (CDCl ３ , room temperature) spectrum is shown.

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

[0090] (Synthesis of Polyphenylene Ether) (Example 1) 2,6-dimethylphenol, 2-allylphenol, and a phenol compound represented by chemical formula IV were used as raw material phenols. A 100 mL two-neck flask was used as a reaction vessel, and a raw material solution was prepared by dissolving 3.61 g (80 mol%) of 2,6-dimethylphenol, 0.507 g (10 mol%) of 2-allylphenol, and 0.882 g (10 mol%) of the phenol compound represented by chemical formula IV in 28.92 g of toluene. Further, di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)]chloride (Cu / TMEDA) 0.119 g, tetramethylethylenediamine (TMEDA) 0.131 g were adjusted, and while blowing dry air into the reaction solution at a flow rate of 17 mL / min, the mixture was stirred at a stirring speed of 350 rpm and reacted at 40 ° C for 15 hours to obtain a reaction solution containing polyphenylene ether. After heating the reaction solution and stopping the blowing of dry air, di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)]chloride (Cu / TMEDA) was removed by filtration, and the mixture was diluted with 1,200 mL of methanol, 4.0 mL of concentrated hydrochloric acid, H ２The precipitate was reprecipitated in 27.0 mL of the mixed solution, filtered under reduced pressure, washed with methanol, and dried at 80° C. for 24 hours to obtain the polyphenylene ether according to Example 1. １ H-NMR (CDCl ３ , room temperature) spectrum is shown.

[0091]

[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 shown in Table 1 were used. １ H-NMR (CDCl ３ , 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 using the following formula from the polymerization ratio X of the repeating units derived from each raw material phenol when the unit derived from the styryl group is set to 1. Here, X ｉ is the polymerization ratio of raw material phenol i, W ｉ and σ respectively represent the molecular weight of the repeating unit structure derived from the raw material phenol i. The number of terminal reactive groups per number average molecular weight was calculated by dividing the number average molecular weight obtained by GPC measurement by the styryl group equivalent obtained by the above formula. The number of terminal reactive groups per number average molecular weight is shown in Table 1. As shown in Table 1, according to Example 1, it is possible to introduce many terminal reactive groups into the terminal portions. Note that, for Reference Example 1, since it does not have a styryl group, the number of terminal reactive groups per number average molecular weight was not calculated.

[0094] (Evaluation) By adjusting the synthesis conditions (reaction time, etc.), a polyphenylene ether according to Reference Example 2 was obtained, which had the same monomer composition as in Reference Example 1 and a weight average molecular weight of 54,400. 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> 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) were mixed to prepare a resin composition. Each resin composition was applied to the shine side of 18 μm thick copper foil so that the film thickness after drying was approximately 20 μm, and dried at 90 ° C. for 30 minutes in a hot air circulation drying oven. Next, the composition was cured in an inert oven at 200 ° C. for 1 hour, and then 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 serve 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 instruments used were a vector network analyzer E5071C manufactured by Keysight Technologies, Inc., 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 Dk and Df of the cured product obtained using the polyphenylene ether of Example 1 were 2.7 and 0.0026, respectively. The Dk and Df of the cured product obtained using the polyphenylene ether of Reference Example 2 were 2.7 and 0.0025. These results demonstrate that low dielectric properties can be maintained even when the phenol compound represented by chemical formula IV is used as a raw material phenol for polyphenylene ether having a branched structure.

[0098] <Tensile Properties> (Measurement Method) Measurement samples were cut to a length of 8 cm and a width of 0.5 cm, and the elongation at break (tensile elongation at break) and tensile strength (tensile strength at break) were measured under the following conditions. The modulus of elasticity was determined from the slope of the strain in the stress-strain curve obtained from 5 MPa to 10 MPa. [Measurement Conditions] Testing machine: Tensile testing machine EZ-SX (Shimadzu Corporation) Distance between chucks: 50 mm Testing speed: 1 mm / min Elongation calculation: (tensile travel distance / distance between chucks) x 100

[0099] (Measurement Results) The cured product obtained using the polyphenylene ether of Example 1 had a modulus of elasticity 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 a modulus of elasticity of 2.5 GPa, a breaking elongation of 3.5%, and a tensile strength of 81 MPa. These results demonstrate that the use of a phenol compound represented by chemical formula IV as a raw material phenol for polyphenylene ether having a branched structure can improve mechanical strength, particularly breaking elongation. CROSS-REFERENCE TO RELATED APPLICATIONS

[0100] This application claims priority based on Japanese Patent Application No. 2023-107452, filed with the Japan Patent Office on June 29, 2023, the entire disclosure of which is incorporated herein by reference in its entirety.

[0101] The cured products obtained using the phenolic compounds of the present disclosure have excellent dielectric properties and heat resistance, and can therefore be used in a variety of applications as materials for constituting electronic components.

Claims

1. A phenolic compound represented by the following chemical formula (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. Polyphenylene ether having a terminal structure represented by the following chemical formula (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 phenolic compound according to claim 1 and is represented by the following chemical formula (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). 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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