Polyphenylene ether, curable composition containing polyphenylene ether, dry film, prepreg, cured product, and electronic component

Abstract

To provide a polyphenylene ether having a branch structure, the polyphenylene ether having low dielectric properties and excellent solvent solubility, facilitating molecular weight control, and being suitable for mass production.SOLUTION: A polyphenylene ether is obtained from feedstock phenols, where the feedstock phenols include: phenols that satisfy at least condition 1; and phenols (X) represented by formula (1). Condition 1: hydrogen atoms present at the ortho position and the para position.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a polyphenylene ether, a curable composition containing the polyphenylene ether, a dry film, a cured product, and an electronic component. [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.

[0005] However, polyphenylene ether is soluble in only limited solvents, and the polyphenylene ether obtained by the method of Non-Patent Document 1 is soluble only in highly toxic solvents such as chloroform and toluene. Therefore, there are problems in that it is difficult to handle the resin varnish and to control exposure to solvents in the process of forming a coating film and curing it for wiring board applications. [Prior art documents] [Non-patent literature]

[0006] [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]

[0007] Under these circumstances, the present inventors discovered that polyphenylene ether having a branched structure synthesized using a specific phenol as a raw material has high solvent solubility (JP 2020-015909 A).

[0008] However, in the course of further research, the present inventors have found that the polyphenylene ether having this branched structure has a problem in that, since it has more polymer ends having polymerization reactivity than the polyphenylene ether having a linear structure, the grown polymers are further polymerized (so-called coupling) with each other, resulting in a rapid increase in molecular weight. Therefore, in order to control the molecular weight of the obtained polyphenylene ether to a desired range, it is necessary to carefully select the raw materials and adjust the production conditions, which may make it unsuitable for mass production.

[0009] In addition, it has been newly discovered that low molecular weight polyphenylene ether synthesized by controlling the molecular weight may have reduced film properties such as mechanical strength when cured due to its low molecular weight.

[0010] Therefore, an object of the present invention is to provide a polyphenylene ether having a branched structure that allows easy control of the molecular weight, suppresses an increase in molecular weight, and provides a cured product with excellent mechanical strength. [Means for solving the problem]

[0011] The present inventors have conducted extensive research and found that the above problems can be solved by a polyphenylene ether obtained from a raw material phenol containing a phenol having a specific structure.

[0012] One aspect of the invention is a polyphenylene ether. The polyphenylene ether is obtained from a raw material phenol, and the raw material phenol contains at least a phenol satisfying the following condition 1 and a phenol (X) represented by the following formula (1). (Condition 1) Contains hydrogen atoms at the ortho and para positions [ka] (In formula (1), R A , R C , R E are each independently a functional group having 1 to 10 carbon atoms, R B , R D are each independently a hydrogen atom or a functional group having 1 to 10 carbon atoms; R A ~R E At least one of is a functional group containing an unsaturated carbon bond.

[0013] The phenol (X) is preferably a compound represented by the following formula (2) or (3). [ka] [ka]

[0014] Another aspect of the invention is a curable composition comprising the polyphenylene ether described above.

[0015] Yet another embodiment of the present invention is a dry film or prepreg obtained by coating or impregnating a substrate with the curable composition.

[0016] Yet another aspect of the present invention is a cured product obtained by curing the curable composition.

[0017] Yet another aspect of the present invention is a laminate comprising the above-mentioned cured product.

[0018] Yet another aspect of the present invention is an electronic component having the cured product. Effect of the Invention

[0019] According to the present invention, it is possible to provide a polyphenylene ether having a branched structure which allows easy control of the molecular weight, suppresses an increase in molecular weight, and provides a cured product with excellent mechanical strength. [Brief description of the drawings]

[0020] [Figure 1] FIG. 1 is a 1H-NMR (CDCl3, room temperature) spectrum of the polyphenylene ether according to Example 1. [Diagram 2] FIG. 2 is a 1H-NMR (CDCl3, room temperature) spectrum of the polyphenylene ether according to Example 2. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] When isomers exist in the described compounds, all possible isomers can be used in the present invention unless otherwise specified.

[0022] In this specification, unless otherwise specified, the term "unsaturated carbon bond" refers to an ethylenic or acetylenic carbon-carbon multiple bond (double bond or triple bond).

[0023] In this specification, the functional group containing an unsaturated carbon bond is not particularly limited, but may be an alkenyl group (e.g., a vinyl group, an allyl group), an alkynyl group (e.g., an ethynyl group), or a (meth)acryloyl group. From the viewpoint of excellent curing properties, a vinyl group, an allyl group, or a (meth)acryloyl group may be selected, and among them, from the viewpoint of excellent low dielectric properties, an allyl group is preferable. Note that the number of carbon atoms of these functional groups containing an unsaturated carbon bond may be, for example, 15 or less, 10 or less, 8 or less, 5 or less, 3 or less, etc.

[0024] In this specification, the term "hydrocarbon group" refers to a group composed only of carbon atoms and hydrogen atoms, but is not particularly limited thereto, and examples thereof include alkyl groups, alkenyl groups, alkynyl groups, aryl groups, and cycloalkyl groups.

[0025] 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".

[0026] In this specification, when the raw material phenols are described using expressions such as "ortho position" and "para position", the position of the phenolic hydroxyl group is taken as the reference (ipso position) unless otherwise specified.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] Hereinafter, a polyphenylene ether, a curable composition containing the polyphenylene ether, and a dry film, a cured product, and an electronic component obtained by using the curable composition will be described.

[0031] <<<Polyphenylene ether>>> <<Raw material phenols>> The raw material phenols for the polyphenylene ether according to this embodiment contain at least a phenol satisfying the following condition 1 and a predetermined phenol (X). (Condition 1) Contains hydrogen atoms at the ortho and para positions

[0032] The raw material phenols may also contain other phenols.

[0033] Each phenol will be described below.

[0034] 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.

[0035] <Phenols that meet at least condition 1> Phenols that satisfy at least condition 1 have hydrogen atoms at the ortho and para positions.

[0036] Moreover, the phenol satisfying at least the condition 1 may further satisfy the following condition 2. (Condition 2) It has a hydrogen atom at the para position and a functional group containing an unsaturated carbon bond.

[0037] 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.

[0038] Phenols satisfying condition 1 have a hydrogen atom at the ortho position, and therefore, when oxidatively polymerized with other 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, the polyphenylene ether obtained from the raw material phenols containing the phenols 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.

[0039] Furthermore, since the phenols satisfying the condition 2 have a functional group containing an unsaturated carbon bond, the polyphenylene ether obtained by using such a phenol as the raw material phenol has a functional group containing an ethylenic or acetylenic carbon-carbon multiple bond. More specifically, the polyphenylene ether obtained from the raw material phenols containing the phenols 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 the two ortho positions of the benzene ring.

[0040] 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.

[0041] 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.

[0042] In the synthesis of polyphenylene ether, the content of phenols (A) 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.

[0043] <Phenols (X)> The phenol (X) has a structure represented by the following formula (1). [ka]

[0044] In formula (1), R A , R C , R Eare each independently a functional group having 1 to 10 carbon atoms, R B , R D are each independently a hydrogen atom or a functional group having 1 to 10 carbon atoms; R A ~R E At least one of is a functional group that contains an unsaturated carbon bond.

[0045] The phenol compound (X) may have only one functional group containing an unsaturated carbon bond, or may have two or more functional groups containing an unsaturated carbon bond.

[0046] As described above, the polyphenylene ether according to this embodiment has a branched structure by containing a phenol satisfying condition 1 as a raw material phenol. Compared with polyphenylene ether having a linear structure, polyphenylene ether having a branched structure has more polymer ends that are reactive for polymerization. Therefore, the grown polymers may further polymerize with each other (i.e., couple), resulting in a rapid increase in molecular weight, making it difficult to control the reaction. Based on such findings, in this embodiment, in addition to the phenols satisfying condition 1, phenols (X) are further combined as the raw material phenols. Since the phenols (X) do not have hydrogen atoms at the highly reactive ortho and para positions, the polymerization reaction stops at the end of the polyphenylene ether molecular chain where the phenols (X) react. Therefore, if the phenols (X) constitute the end of the polyphenylene ether in an appropriate amount, the rapid increase in molecular weight (coupling reaction) that occurs in the synthesis of polyphenylene ether having a branched structure can be suppressed. The polyphenylene ether obtained in this manner is likely to have excellent storage stability because unintended molecular weight increase is suppressed.

[0047] Also, as in U.S. Pat. No. 3,440,217, a method is known in which 3-substituted phenols such as 2,6-dimethylphenol and 2,4,6-trimethylphenol are used as raw phenols to control the molecular weight of polyphenylene ether having a linear structure. However, in linear polyphenylene ether, the polymerization reaction proceeds only at one end of the polyphenylene ether molecular chain, and the polymerization reaction stops at the stage where the 3-substituted phenol reacts. Therefore, the present inventors have found that in linear polyphenylene ether in which the molecular weight is controlled using a 3-substituted phenol, the molecular weight of the polyphenylene ether becomes extremely low, and the mechanical strength may be significantly reduced. In this regard, in the present embodiment, it has been found that by using phenols (X) as raw phenols for polyphenylene ether having a branched structure, it is possible to obtain a polyphenylene ether having a desired molecular weight range without excessively suppressing the increase in molecular weight. In polyphenylene ether having a branched structure, polymerization proceeds at two or more reactive ends. Therefore, even if a phenol (X) reacts, polymerization can be performed at another reactive end. Since the increase in molecular weight is not excessively suppressed, it is presumed that a polyphenylene ether in a desired molecular weight range can be obtained.

[0048] As a result, the reaction can be easily controlled, and polyphenylene ether having a desired molecular weight range (particularly, polyphenylene ether having an industrially useful weight average molecular weight of 5,000 to 300,000) can be efficiently produced while maintaining the excellent performance (low dielectric properties, excellent solvent solubility) derived from the branched structure. Such polyphenylene ether has excellent mechanical strength of the cured product while controlling the molecular weight.

[0049] In addition, the phenol (X) has a functional group containing at least an unsaturated carbon bond. In other words, the polyphenylene ether having a branched structure obtained by using the phenol (X) has a functional group containing at least an unsaturated carbon bond (derived from the phenol (X)), and exhibits crosslinkability. In addition, as described above, the phenol (X) moderately constitutes the terminal portion of the polyphenylene ether, so that the polyphenylene ether having a branched structure obtained exhibits crosslinkability at the terminal portion of the branched structure, and while maintaining excellent solvent solubility, the crosslinking reactivity of the polyphenylene ether is easily improved (or the mechanical strength of the obtained cured product is easily improved). It is presumed that the synergistic effect of each component according to this embodiment makes it possible to obtain polyphenylene ether having excellent mechanical strength of a cured product while controlling the molecular weight.

[0050] The functional group containing an unsaturated carbon bond contained in the phenol (X) is preferably a functional group containing an unsaturated double bond and having 3 or more carbon atoms. When the functional group containing an unsaturated double bond has 3 or more carbon atoms, the ease of production and storage stability are excellent.

[0051] From the viewpoint of further enhancing the effects of the present disclosure, the phenol (X) is preferably as follows.

[0052] In the formula (1), the functional group containing an unsaturated carbon bond is preferably a hydrocarbon group. When the functional group containing an unsaturated carbon bond is a hydrocarbon group, it is preferable that the functional group contains 3 to 10 carbon atoms, 3 to 5 carbon atoms, or 3 carbon atoms. More specifically, the hydrocarbon group containing an unsaturated carbon bond is [-(CH2) n -CH=CH2] (n is an integer of 1 to 8). The n is more preferably an integer of 1 to 3, and particularly preferably 1.

[0053] In formula (1), R A , R C , R Eis preferably each independently a hydrocarbon group having 10 or less carbon atoms, 5 or less carbon atoms, or 3 or less carbon atoms.

[0054] In formula (1), R A , R C , R E It is preferable that one or more of R A , R C , R E It is preferable that one of the above is a functional group containing an unsaturated carbon bond, and the other is a functional group not containing an unsaturated carbon bond.

[0055] In formula (1), at least R C is a functional group containing an unsaturated carbon bond, from the viewpoint of obtaining a cured product having particularly excellent breaking elongation. Since a functional group containing an unsaturated carbon bond at the para position has a higher crosslinking reactivity than a functional group containing an unsaturated carbon bond at the ortho position or meta position, it is presumed that a polyphenylene ether having a cured product having particularly excellent mechanical strength can be obtained. In addition, in formula (1), at least R A , R E It is particularly preferred from the viewpoint of obtaining a cured product having a high elastic modulus that any one of the above groups is a functional group containing an unsaturated carbon bond.

[0056] In formula (1), R B , R D are preferably each independently hydrogen or a hydrocarbon group having 10 or less carbon atoms, hydrogen or a hydrocarbon group having 5 or less carbon atoms, hydrogen or a hydrocarbon group having 3 or less carbon atoms, hydrogen or a hydrocarbon group having 1 carbon atom, or hydrogen.

[0057] In formula (1), R B , R D When is a hydrocarbon group, it is preferably a hydrocarbon group containing no unsaturated carbon bonds.

[0058] In formula (1), as described above, R A ~R E At least one of R is a functional group containing an unsaturated carbon bond. In this case, RA ~R E In the above, the substituent other than hydrogen that does not fall under the category of functional groups containing an unsaturated carbon bond is preferably a hydrocarbon group having 1 to 10, 1 to 5, or 1 to 3 carbon atoms.

[0059] Specific examples of the phenols (X) include the compound represented by the following formula (2) (4-allyl-2,6-dimethylphenol) or the compound represented by the following formula (3) (2-allyl-4,6-dimethylphenol). The phenols (X) can be produced using known methods, such as the synthesis method described in WO2021 / 070714.

[0060] [ka]

[0061] [ka]

[0062] In the synthesis of polyphenylene ether, the content of the phenol (X) relative to the total amount of the 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.

[0063] The ratio of the content (mol%) of phenols (X) to the content (mol%) of phenols satisfying condition 1 based on the total amount of raw material phenols (phenols (X) / phenols satisfying condition 1) is preferably 0.1 to 10.0, 0.2 to 5.0, or 0.5 to 2.0.

[0064] <Other phenols> The other phenols are phenols that do not satisfy condition 1 and do not fall under phenol (X).

[0065] Examples of other phenols include (1) phenols that do not satisfy condition 1, satisfy condition 2, and do not fall under phenols (X), and (2) phenols that do not satisfy either condition 1 or condition 2, and do not fall under phenols (X).

[0066] Phenols that do not satisfy condition 1, but do not satisfy condition 2, and do not fall under phenols (X) are, for example, phenols that have a hydrogen atom at the para position and a hydrocarbon group at each ortho position, at least one of which has 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.

[0067] Phenols that do not satisfy either condition 1 or condition 2 and do not fall under the category of phenols (X) are, for example, phenols that have a hydrogen atom at the para position and a functional 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.

[0068] 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.

[0069] Furthermore, examples of phenols that do not satisfy either condition 1 or condition 2 and do not fall under the category of phenols (X) 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.

[0070] The other phenols may be used alone or in combination of two or more.

[0071] When other phenols are used in the synthesis of polyphenylene ether, the content of the 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.

[0072] <<Production method of polyphenylene ether>> The polyphenylene ether of the present disclosure 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.

[0073] <<Polyphenylene Ether Properties>> The weight average molecular weight of the polyphenylene ether is preferably from 5,000 to 40,000, more preferably from 8,000 to 30,000, and even more preferably from 10,000 to 25,000. The number average molecular weight of the polyphenylene ether is preferably from 5,000 to 20,000, and more preferably from 5,000 to 10,000.

[0074] The molecular weight of polyphenylene ether depends on the type of raw material phenol used, but can be adjusted by changing the reaction temperature, reaction time, etc. during synthesis. In addition, by increasing the ratio of phenol (X) in the raw material phenols or the ratio of other phenols that do not have hydrogen atoms at the para and ortho positions, the polymerization reaction is suppressed, the rate of increase in molecular weight is slowed down, and it becomes easy to control the molecular weight of polyphenylene ether.

[0075] <<<Curable composition>>> The curable composition includes the polyphenylene ether according to this embodiment. The curable composition may also contain other components.

[0076] The content of the polyphenylene ether in the curable composition is preferably 40 to 90 mass %, more preferably 50 to 80 mass %, based on the total amount excluding volatile components and inorganic fillers in the curable composition.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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.

[0081] 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.

[0082] 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.

[0083] 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.

[0084] <<<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.

[0085] 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.

[0086] The film materials for the carrier film and the cover film may be any of those known to be used for dry films.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] The prepreg can be obtained, for example, by impregnating a substrate such as glass cloth with a curable composition and drying it.

[0091] <<<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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] <<<Electronic Components>>> The electronic component has the cured product of the present disclosure described above. The cured product of the present disclosure has excellent dielectric properties, heat resistance, and mechanical strength, and can therefore be used for a variety of applications as a material for constituting laminates and electronic components.

[0096] 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). EXAMPLES

[0097] <<Synthesis of polyphenylene ether>> <Example 1> As raw material phenols, 2,6-dimethylphenol, 2-allylphenol, and 4-allyl-2,6-dimethylphenol were used. A 500mL separable flask was used as a reaction vessel, and 34.51g (80mol%) of 2,6-dimethylphenol, 4.71g (10mol%) of 2-allylphenol, and 5.70g (10mol%) of 4-allyl-2,6-dimethylphenol were dissolved in 286.30g of toluene to prepare a raw material solution. In addition, 1.04g of di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) and 1.06g of tetramethylethylenediamine (TMEDA) were adjusted, and the reaction solution was stirred at a stirring speed of 200 rpm while blowing dry air into the reaction solution at a flow rate of 150mL / 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 HO. The precipitate was filtered under reduced pressure, washed with methanol, and then dried at 80° C. for 24 hours to obtain the polyphenylene ether of Example 1. FIG. 1 shows the polyphenylene ether of Example 1. 1 H-NMR (CDCl3, room temperature) spectrum is shown.

[0098] <Example 2> The polyphenylene ether of Example 2 was obtained in the same manner as in Example 1, except that 2,6-dimethylphenol, 2-allylphenol, and 2-allyl-4,6-dimethylphenol were used as raw material phenols and the production conditions shown in Table 1 were used. FIG. 2 shows the polyphenylene ether of Example 2. 1 H-NMR (CDCl3, room temperature) spectrum is shown.

[0099] <Comparative Example 1> The polyphenylene ether according to Comparative Example 1 was obtained in the same manner as in Example 1, except that 2,6-dimethylphenol, 2-allylphenol, and 2,4,6-trimethylphenol were used as raw material phenols and the production conditions shown in Table 1 were set.

[0100] <Reference example 1> The 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 set.

[0101] <Molecular weight> The weight average molecular weight and number average molecular weight were measured for the polyphenylene ethers of Example 1, Example 2, Comparative Example 1, and Reference Example 1. The measurement results are shown in Table 1.

[0102] <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 functional group equivalent is calculated from the polymerization ratio X of the repeating structure derived from each raw material phenol when the structure derived from the phenol compound X is set to 1, using the following formula. JPEG2025006571000007.jpg14159 Here is X i is the polymerization ratio of raw phenol i, W i and x and y 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 functional group equivalent obtained by the above formula. The number of terminal reactive groups per number average molecular weight is shown in Table 1. In addition, in Comparative Example 1 and Reference Example 1, since there is no terminal structure derived from the phenol compound X, the number of terminal reactive groups per number average molecular weight was not calculated.

[0103] As shown in Table 1, by using a phenol (X) having specific functional groups at least at the para-position and the ortho-position, as shown in formula (1), as a raw material phenol for polyphenylene ether having a branched structure, it is possible to obtain polyphenylene ether with a lower molecular weight, and it was shown that an increase in molecular weight can be suppressed. On the other hand, the polyphenylene ether of Reference Example 1 was a polyphenylene ether with a higher molecular weight than the polyphenylene ethers of Examples 1 and 2, despite the same reaction time. Furthermore, as shown in Table 1, according to Examples 1 and 2, it is possible to introduce many reactive groups (allyl groups) into the terminal portions. In addition, in Comparative Example 1 and Reference Example 1, the number of terminal reactive groups per number average molecular weight was not calculated because the phenol compound X was not used.

[0104] [Table 1]

[0105] <<Evaluation>> The polyphenylene ethers according to Examples 1 and 2 and the polyphenylene ether according to Comparative Example 1 were evaluated.

[0106] <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 single cured film (measurement sample). Comparative Example 1 is a polyphenylene ether that can suppress the molecular weight increase to the same extent as Examples 1 and 2, but after curing, many cracks occurred in the cured product, and a single cured film could not be obtained. On the other hand, in both Examples 1 and 2, no cracks occurred in the cured product, and a single cured film could be obtained, so it was confirmed that the mechanical strength of the cured product was improved compared to Comparative Example 1. In addition, since a single cured film could not be obtained in Comparative Example 1, the following evaluation was not performed.

[0107] <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 was 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.

[0108] (Measurement results) The cured product obtained using the polyphenylene ether of Example 1 had a Dk of 2.4. The cured product obtained using the polyphenylene ether of Example 2 had a Dk of 2.7. From the above results, it was shown that even when the phenol compound (X) (a phenol having a specific functional group at least at the para-position and the ortho-position) is used as a raw material phenol for polyphenylene ether having a branched structure, the polyphenylene ether has excellent low dielectric properties.

[0109] <Tensile properties> (Measurement method) A measurement sample was cut to a length of 8 cm and a width of 0.5 cm, and the breaking elongation (tensile breaking elongation) was 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

[0110] (Measurement results) The cured product obtained using the polyphenylene ether of Example 1 had an elastic modulus of 2.4 GPa and an elongation at break of 3.4%. The cured product obtained using the polyphenylene ether of Example 2 had an elastic modulus of 3.9 GPa and an elongation at break of 1.4%. The above results show that by using the phenol compound (X) (phenols having predetermined functional groups at least at the para-position and the ortho-position) as a raw material phenol for polyphenylene ether having a branched structure, excellent mechanical strength can be obtained while controlling the molecular weight. In particular, it was shown that by using a phenol having a predetermined hydrocarbon group at the para-position, excellent elongation at break can be obtained, and by using a phenol having a predetermined hydrocarbon group at the ortho-position, excellent elastic modulus can be obtained.

Claims

1. A polyphenylene ether obtained from a raw material phenol, The polyphenylene ether is characterized in that the raw material phenols contain at least a phenol satisfying the following condition 1 and a phenol (X) represented by the following formula (1): (Condition 1) Contains hydrogen atoms at the ortho and para positions 【Chemistry 1】 (In formula (1), R Ａ , R Ｃ , R Ｅ are each independently a functional group having 1 to 10 carbon atoms; R Ｂ , R Ｄ are each independently a hydrogen atom or a functional group having 1 to 10 carbon atoms; R Ａ ~R Ｅ At least one of is a functional group containing an unsaturated carbon bond.

2. The polyphenylene ether according to claim 1 , wherein the phenol (X) is a compound represented by the following formula (2) or the following formula (3): 【Chemistry 2】 【Chemistry 3】

3. A curable composition comprising the polyphenylene ether according to claim 1 or 2.

4. A dry film or prepreg obtained by coating or impregnating a substrate with the curable composition according to claim 3.

5. A cured product obtained by curing the curable composition according to claim 3.

6. A laminate comprising the cured product according to claim 5.

7. An electronic part comprising the cured product according to claim 5 .

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