JP2023060737A - Polyphenylene ether, curable composition containing polyphenylene ether, dry film, cured product, and electronic component - Google Patents

Abstract

To provide a polyphenylene ether having a branched structure, wherein the polyphenylene ether not only has low dielectric properties and excellent solubility in solvents, but also facilitates control of its molecular weight and is suitable for mass production.SOLUTION: A polyphenylene ether can be obtained from raw material phenols including phenols satisfying at least condition 1 below and phenols satisfying at least condition 2 below, wherein the content of phenols satisfying condition 2 is 15 mol% or less with respect to the total amount of the raw material phenols. (Condition 1) The phenol has hydrogen atoms at the ortho- and para-positions. (Condition 2) The phenol has hydrogen atoms at the para-position and has a C3-C15 branched or cyclic hydrocarbon group and/or a C4-C15 linear hydrocarbon group.SELECTED DRAWING: None

Description

The present invention relates to polyphenylene ethers, curable compositions containing polyphenylene ethers, dry films, cured products and electronic parts.

With the spread of high-capacity high-speed communications represented by fifth-generation communication systems (5G) and millimeter-wave radars for ADAS (advanced driving systems) in automobiles, signals from communications equipment have become increasingly high-frequency.

However, when epoxy resin or the like is used as a wiring board material, the dielectric constant (Dk) and dielectric loss tangent (Df) are not sufficiently low. Problems such as signal attenuation and heat generation occurred. Therefore, polyphenylene ether, which has excellent low dielectric properties, has been used.

In addition, Non-Patent Document 1 proposes a polyphenylene ether having improved heat resistance by introducing an allyl group into the molecule of the polyphenylene ether to form a thermosetting resin.

However, polyphenylene ether is soluble in limited solvents, and the polyphenylene ether obtained by the method of Non-Patent Document 1 is only soluble in highly toxic solvents such as chloroform and toluene. Therefore, there is a problem that it is difficult to handle the resin varnish and control solvent exposure in the process of coating and curing such as wiring board applications.

J. Nunoshige, H. Akahoshi, Y. Shibasaki, M. Ueda, J. Polym. Sci. Part A: Polym. Chem. 2008, 46, 5278-3223.

Under such circumstances, the present inventors have found that polyphenylene ether having a branched structure synthesized from a specific phenol as a raw material has high solvent solubility (Japanese Patent Application Laid-Open No. 2020-055999).

However, the polyphenylene ether having a branched structure disclosed in the above document has more polymer terminals having polymerization reactivity than the polyphenylene ether having a linear structure, so that the grown polymers are further polymerized (so-called coupling ), and there is a problem that the molecular weight increases rapidly. Therefore, in order to control the molecular weight of the polyphenylene ether to be obtained within a desired range, selection of raw materials, fine adjustment of production conditions, etc. are required, and in some cases it is unsuitable for mass production.

Accordingly, an object of the present invention is to provide a polyphenylene ether having a branched structure that not only has low dielectric properties and excellent solvent solubility, but also allows easy control of the molecular weight and is suitable for mass production.

The present inventors have conducted extensive research and found that the above problems can be solved by a polyphenylene ether composed of raw material phenols having a specific structure. That is, the present invention is as follows.

The present invention is obtained from a raw material phenol containing at least a phenol satisfying the following condition 1 and a phenol satisfying at least the following condition 2,
A polyphenylene ether in which the content of phenols satisfying condition 2 is 15 mol % or less relative to the total amount of raw material phenols.
(Condition 1)
Having hydrogen atoms at the ortho and para positions (Condition 2)
having a hydrogen atom at the para position and having a branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or a linear hydrocarbon group having 4 to 15 carbon atoms

The branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or the straight chain hydrocarbon group having 4 to 15 carbon atoms in the phenols satisfying condition 2 above is preferably a tert-butyl group.

The present invention may be a curable composition containing the polyphenylene ether.

The present invention may also be a dry film having a resin layer comprising the curable composition.

The present invention may be a cured product of a resin layer comprising the curable composition or the curable resin.

The present invention may be an electronic component having the cured product.

INDUSTRIAL APPLICABILITY According to the present invention, there is provided a polyphenylene ether having a branched structure that not only has low dielectric properties and excellent solvent solubility, but also facilitates control of molecular weight and is suitable for mass production.

The polyphenylene ether of the present invention and the curable composition containing the polyphenylene ether will be described below, but the present invention is not limited to the following.

Where an illustrated compound exists in isomers, all possible isomers can be used in the present invention unless otherwise stated.

In the present invention, "unsaturated carbon bond" means an ethylenic or acetylenic multiple bond (double bond or triple bond) between carbon atoms unless otherwise specified. In the present invention, the functional group having an unsaturated carbon bond is not particularly limited. mentioned. These functional groups having unsaturated carbon bonds can have, for example, 15 or less, 10 or less, 8 or less, 5 or less, or 3 or less carbon atoms.

In the present invention, phenols that are used as raw materials for polyphenylene ether (PPE) and that can be constituent units of polyphenylene ether are collectively referred to as "raw material phenols."

In the present invention, when "ortho-position", "para-position" and the like are used when describing raw material phenols, the position of the phenolic hydroxyl group is used as the reference (ipso-position) unless otherwise specified.

In the present invention, simply expressing "ortho position" or the like means "at least one of the ortho positions" or the like. Therefore, as long as there is no particular contradiction, the simple expression "ortho position" may be interpreted as indicating either one of the ortho positions or both of the ortho positions.

In this specification, monohydric phenols are mainly disclosed as raw material phenols, but polyhydric phenols may be used as raw material phenols to the extent that the effects of the present invention are not impaired.

In this specification, when the upper and lower limits of a numerical range are stated separately, it is assumed that all combinations of each lower limit and each upper limit are substantially stated in a consistent range. do.

<<<Polyphenylene ether>>>
The polyphenylene ether according to the present embodiment is a polyphenylene ether obtained from raw material phenols containing at least phenols satisfying condition 1 below and phenols satisfying at least condition 2 below.
(Condition 1)
Having hydrogen atoms at the ortho and para positions (Condition 2)
having a hydrogen atom at the para position and having a branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or a linear hydrocarbon group having 4 to 15 carbon atoms

The raw material phenols may contain other phenols that do not satisfy the conditions 1 and 2.

Here, that the raw material phenols include phenols satisfying at least condition 1 and phenols satisfying at least condition 2 means that at least one of the following forms 1 and 2 is applicable.
(Form 1)
Raw material phenols contain at least phenols satisfying both conditions 1 and 2.
(Form 2)
The raw material phenols include at least phenols that satisfy condition 1 but do not satisfy condition 2 and phenols that satisfy condition 1 but not condition 2.

In form 1, the raw material phenols may further contain phenols that meet condition 1 but do not meet condition 2 and/or phenols that meet condition 2 but do not meet condition 1.

Hereinafter, a branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or a linear hydrocarbon group having 4 to 15 carbon atoms possessed by a phenol that satisfies condition 2 is simply referred to as a "predetermined hydrocarbon group". sometimes. The predetermined hydrocarbon group may be a hydrocarbon group having both a cyclic structure and a branched structure.

<<Raw material phenols>>
<Phenols satisfying condition 1>
Phenols satisfying Condition 1 are phenols having hydrogen atoms at the ortho- and para-positions.

Phenols satisfying Condition 1 may have one or more predetermined hydrocarbon groups. In this case, it becomes the raw material phenols of form 1 mentioned above.

Phenols satisfying condition 1 may have a functional group containing an unsaturated carbon bond.

Phenols satisfying Condition 1 are, for example, compounds represented by Formula 1 below.

In Formula 1, R ¹¹ to R ¹³ are each independently a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms (preferably 1 to 4 carbon atoms).

Specific examples of phenols satisfying condition 1 include phenol, o-cresol, m-cresol, 2-ethylphenol, 3-ethylphenol, 2,3-xylenol, 2,5-xylenol, 3,5- xylenol, 2-n-butylphenol, 3-n-butylphenol, 2-isobutylphenol, 3-isobutylphenol, 2-s-butylphenol, 3-s-butylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 2- Phenylphenol, 3-phenylphenol, 2-dodecylphenol, 2-vinylphenol, 3-vinylphenol, 2-allylphenol, 3-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 and the like can be mentioned.

Phenols satisfying condition 1 may be used alone or in combination of two or more.

Phenols that satisfy condition 1 have a hydrogen atom at the ortho position, so that an ether bond can be formed not only at the ipso and para positions but also at the ortho position when oxidatively polymerized with phenols. Therefore, polyphenylene ether obtained by using such phenols as raw material phenols can form a branched chain structure.

Specifically, polyphenylene ethers obtained from phenols that satisfy Condition 1 are partly branched by benzene rings ether-bonded at at least three positions, ipso-position, ortho-position, and para-position. Become.

A polyphenylene ether having such a branched structure in its skeleton is called a branched polyphenylene ether. Such branched polyphenylene ethers provide excellent solubility in organic solvents.

The content of phenols satisfying condition 1 is preferably 1 mol% or more, 2 mol% or more, 5 mol% or more, or 8 mol% or more, and is 40 mol% or less and 30 mol% with respect to the total amount of raw material phenols. Below, it is preferably 20 mol % or less, or 15 mol % or less.

The content of phenols that satisfies Condition 1 is calculated based on the total amount of raw material phenols used in the synthesis of the branched polyphenylene ether.

<Phenols satisfying condition 2>
Phenols that satisfy condition 2 have a hydrogen atom at the para position and have one or more branched or cyclic hydrocarbon groups having 3 to 15 carbon atoms and/or linear hydrocarbon groups having 4 to 15 carbon atoms. It is a phenol having (preferably one or two).

Phenols satisfying condition 2 may have one or more straight-chain hydrocarbon groups having 1 to 3 carbon atoms in addition to the predetermined hydrocarbon group.

Phenols satisfying condition 2 may have a functional group containing an unsaturated carbon bond.

Phenols satisfying condition 2 are, for example, compounds represented by formula 2 below.

In Formula 2, at least one of R ²¹ to R ²⁴ is a branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or a linear hydrocarbon group having 4 to 15 carbon atoms, and the rest are each independently is a hydrogen atom or a straight-chain hydrocarbon group having 1 to 3 carbon atoms.

The branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or the linear hydrocarbon group having 4 to 15 carbon atoms should be saturated (having no unsaturated carbon bonds) from the viewpoint of low dielectric properties. is preferred.

A branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or a linear hydrocarbon group having 4 to 15 carbon atoms has a stronger effect of suppressing an increase in the molecular weight of the polyphenylene ether as the number of carbon atoms increases. Therefore, in order to control the polymerization reactivity and molecular weight of polyphenylene ether in a well-balanced manner, a branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or a linear hydrocarbon group having 4 to 15 carbon atoms is A branched or cyclic hydrocarbon group having 3 to 10 carbon atoms and/or a linear hydrocarbon group having 4 to 10 carbon atoms is preferred, and a branched or cyclic hydrocarbon group having 3 to 6 carbon atoms and/or a 4 to 10 carbon atoms A straight chain hydrocarbon group of 6 is more preferred, a branched hydrocarbon group of 3 to 4 carbon atoms is even more preferred, and a branched hydrocarbon group of 4 carbon atoms is particularly preferred. More specifically, it is preferably a tert-butyl group.

Specific examples of phenols that satisfy condition 2 include:
Phenols having a branched hydrocarbon group having 3 to 15 carbon atoms include 2-isobutylphenol, 3-isobutylphenol, 2-s-butylphenol, 3-s-butylphenol, 2-tert-butylphenol, 3-tert-butylphenol, 2-methyl-6-tert-butylphenol, 2,6-di-tert-butylphenol, 2,6-dibutenylphenol, 2,6-diisobutenylphenol, 2,6-diisopentenylphenol and the like;
Phenols having a cyclic hydrocarbon group having 3 to 15 carbon atoms include 2-phenylphenol, 3-phenylphenol, 2,6-diphenylphenol, 2,6-ditolylphenol, 2-allyl-6-phenylphenol, 2-allyl-6-styrylphenol, 2-methyl-6-styrylphenol and the like;
2-n-butylphenol, 3-n-butylphenol, 2-dodecylphenol and the like as phenols having a linear hydrocarbon group with 4 to 15 carbon atoms;
is mentioned.

Only one kind of phenols satisfying condition 2 may be used, or two or more kinds thereof may be used.

The content of phenols satisfying condition 2 is preferably 15 mol % or less with respect to the total amount of raw material phenols.

In addition, the content of phenols satisfying condition 2 may be more than 0 mol%, more specifically, 0.1 mol% or more, 0.5 mol% or more, 1 mol% or more with respect to the total amount of raw material phenols. , or 2 mol % or more.

The content of phenols that satisfies condition 2 is calculated based on the total amount of raw material phenols used in the synthesis of the branched polyphenylene ether.

As described above, the polyphenylene ether of the present invention has a branched structure by containing phenols satisfying condition 1 as raw material phenols.
Polyphenylene ether having a branched structure has more polymer terminals with polymerization reactivity than polyphenylene ether having a linear structure, so the grown polymers further polymerize (so-called coupling), resulting in a rapid increase in molecular weight. Therefore, it was not easy to control the reaction.
Based on these findings, in the present invention, as raw material phenols, a phenol satisfying condition 1 is combined with a phenol satisfying condition 2 at a specific content, so that a predetermined hydrocarbon group has an appropriate steric It causes obstacles, suppresses the rapid increase in molecular weight that occurs in the synthesis of polyphenylene ether having a branched structure, and facilitates control of the reaction. As a result, while maintaining the excellent performance derived from the branched structure, polyphenylene ether of a predetermined molecular weight (in particular, industrially useful number average molecular weight 5,000 to 30,000 and / or weight average molecular weight 10 ,000 to 150,000) can be efficiently produced.

On the other hand, the above effect of suppressing the increase in molecular weight can also be obtained by phenol having an allyl group such as 2-allyl-6-methylphenol, although it is not as good as the present invention. However, allyl groups tend to degrade dielectric properties and the cost of such starting phenols is also high. According to the present invention, it is possible to obtain a polyphenylene ether that is more excellent in terms of low dielectric properties and production costs compared to the case where the molecular weight is suppressed only by phenol having an allyl group.

Here, phenols that satisfy condition 2 have a linear hydrocarbon group with 3 or less carbon atoms (preferably a methyl group or an ethyl group) at both or one ortho position (preferably, either one ortho position). , more preferably a methyl group). When the phenols satisfying condition 2 have such a structure, it is believed that steric hindrance can be further promoted within a range in which physical properties are not likely to be affected, and the effect of suppressing the molecular weight can be further improved.

<Other phenols>
In the present invention, phenols other than the raw material phenols described above can be contained within a range that does not impair the effects of the invention. For example, phenols (additional phenols) having a hydrogen atom at the para position, no hydrogen atom at the ortho position, and no predetermined hydrocarbon group can be preferably used.

The phenol for addition may have a functional group containing an unsaturated carbon bond as a hydrocarbon group having 3 or less carbon atoms.

The additional phenols are, for example, compounds represented by the following formulas.

In Formula 3, R ³¹ and R ³⁴ are each independently a linear hydrocarbon group having 1 to 3 carbon atoms, and R ³² and R ³³ are each independently a hydrogen atom or 1 carbon atom. ∼3 hydrocarbon groups.

Specific examples of additional phenols include 2,6-dimethylphenol, 2,3,6-trimethylphenol, 2-methyl-6-ethylphenol, 2-allyl-6-methylphenol, 2-allyl- 6-ethylphenol, 2,6-divinylphenol, 2,6-diallylphenol, 2-vinyl-6-methylphenol, 2-vinyl-6-ethylphenol and the like.

The content of the additional phenols can be 50 mol % or more, 60 mol % or more, 70 mol % or more, or 80 mol % or more with respect to the total amount of raw material phenols.

By containing an appropriate amount of additional phenols together with the phenols satisfying condition 1 and the phenols satisfying condition 2, the reaction during synthesis of polyphenylene ether can be easily controlled.

However, from the viewpoint of low dielectric properties and production costs, the content of the additional phenols having allyl groups is less than 20 mol%, less than 10 mol%, less than 5 mol%, or 1 mol% with respect to the total amount of raw material phenols. It is preferably less than

Furthermore, the other phenols may contain phenols other than the additional phenols (for example, phenols having no hydrogen atom at the para-position, etc.).

<Phenols Having a Functional Group Containing an Unsaturated Carbon Bond>
Raw material phenols (phenols satisfying condition 1, phenols satisfying condition 2, and other phenols) may have a functional group containing an unsaturated carbon bond.

The unsaturated carbon bond is introduced into the side chain of the polyphenylene ether obtained by the raw material phenol containing a phenol containing a functional group having an unsaturated carbon bond. Such a polyphenylene ether can be three-dimensionally crosslinked by the curing reaction of the unsaturated carbon bonds, and can be used as a curable polyphenylene ether.

The content of the raw material phenol containing a functional group having an unsaturated carbon bond can be appropriately set according to the application, etc., but from the viewpoint of low dielectric properties, for example, 0 mol%, It can be 1 mol % or more, 2 mol % or more, 3 mol % or more, or 5 mol % or more, and can be 99 mol % or less, 50 mol % or less, 30 mol % or less, or 20 mol % or less.

The content of raw material phenols containing a functional group having an unsaturated carbon bond is calculated based on the total amount of raw material phenols used in the synthesis of the branched polyphenylene ether.

<<Synthesis Method>>
The polyphenylene ether according to the present embodiment can be synthesized by applying a conventionally known polyphenylene ether synthesis method (polymerization conditions, presence or absence of catalyst, type of catalyst, etc.) except for using the raw material phenols described above. is.

Next, an example of a method for synthesizing polyphenylene ether will be described.

Polyphenylene ether is prepared, for example, by preparing a polymerization solution containing a raw material phenol, a catalyst and a solvent (polymerization solution preparation step), at least passing oxygen through the solvent (oxygen supply step), and adding oxygen to the polymerization solution containing can be synthesized by oxidatively polymerizing phenols (polymerization step).

The polymerization solution preparation step, oxygen supply step and polymerization step will be described below. In addition, each step may be performed continuously, a part or all of a certain step and a part or all of another step may be performed simultaneously, or a step may be interrupted and another step may be performed. For example, the oxygen supply step may be performed during the polymerization solution preparation step or during the polymerization step. In addition, this method for synthesizing polyphenylene ether may include other steps as necessary. Other steps include, for example, a step of extracting the polyphenylene ether obtained by the polymerization step (for example, a step of performing reprecipitation, filtration and drying), the modification step described above, and the like.

<Polymerization solution preparation step>
The polymerization solution preparation step is a step of mixing raw materials containing phenols to be polymerized in the polymerization step described below to prepare a polymerization solution. Raw materials for the polymerization solution include raw material phenols, catalysts, and solvents.

(catalyst)
The catalyst is not particularly limited, and may be an appropriate catalyst used in oxidative polymerization of polyphenylene ether.

Examples of catalysts include amine compounds and metal amine compounds composed of heavy metal compounds such as copper, manganese and cobalt and amine compounds such as tetramethylethylenediamine. It is preferable to use a copper-amine compound in which a copper compound is coordinated to an amine compound. Only one kind of catalyst may be used, or two or more kinds thereof may be used.

The content of the catalyst is not particularly limited, but may be, for example, 0.1 to 0.6 mol % with respect to the total amount of raw material phenols in the polymerization solution.

Such a catalyst may be preliminarily dissolved in an appropriate solvent.

(solvent)
The solvent is not particularly limited, and may be an appropriate solvent used in oxidative polymerization of polyphenylene ether. As the solvent, it is preferable to use one capable of dissolving or dispersing the phenolic compound and the catalyst.

Specific examples of the solvent include aromatic hydrocarbons such as benzene, toluene, xylene and ethylbenzene; halogenated aromatic hydrocarbons such as chloroform, methylene chloride, chlorobenzene, dichlorobenzene and trichlorobenzene; nitro compounds such as nitrobenzene; Methyl ethyl ketone (MEK), cyclohexanone, tetrahydrofuran, ethyl acetate, N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), propylene glycol monomethyl ether acetate (PMA), diethylene glycol monoethyl ether acetate (CA) etc. Only one solvent may be used, or two or more solvents may be used.

The solvent may contain water, a solvent compatible with water, or the like.

The content of the solvent in the polymerization solution is not particularly limited and can be adjusted as appropriate.

(Other raw materials)
The polymerization solution may contain other raw materials as long as the effects of the present embodiment are not impaired.

<Oxygen supply step>
The oxygen supply step is a step of passing an oxygen-containing gas into the polymerization solution.

The ventilation time of the oxygen gas and the oxygen concentration in the oxygen-containing gas to be used can be appropriately changed according to atmospheric pressure, temperature, and the like.

<Polymerization process>
The polymerization step is a step of oxidative polymerization of phenols in the polymerization solution under the condition that oxygen is supplied to the polymerization solution.

Specific polymerization conditions are not particularly limited, but for example, stirring may be performed at 25 to 100° C. for 2 to 24 hours. The stirring means is not particularly limited, and known means (for example, paddle blades, etc.) can be used.

<<<molecular weight of polyphenylene ether>>>
The polyphenylene ether according to this embodiment preferably has a number average molecular weight of 5,000 to 30,000. Further, the polyphenylene ether according to the present embodiment preferably has a weight average molecular weight of 10,000 to 150,000. Furthermore, the polyphenylene ether according to the present embodiment preferably has a polydispersity index (PDI: weight average molecular weight/number average molecular weight) of 1.1 to 20, more preferably 1.2 to 15. 1.3 to 10 are particularly preferred.

By setting the molecular weight to such a range, the film formability of the curable composition can be improved while maintaining the solubility in the solvent.

In the present embodiment, the number average molecular weight and weight average molecular weight are obtained by measuring by gel permeation chromatography (GPC) and converting from a calibration curve prepared using standard polystyrene.

<<<Curable Composition>>>
The polyphenylene ether having a branched structure according to this embodiment can be combined with known components to form a curable composition.

Examples of known components include silica, peroxides, cross-linking curing agents, maleimide compounds, elastomers, and the like. In addition, other known components include flame retardant improvers (phosphorus compounds, etc.), cellulose nanofibers, polymer components (cyanate ester resins, epoxy resins, phenolic novolac resins and other resin components, polyimides, polyamides and other organic compounds). polymer), dispersants, thermosetting catalysts, thickeners, antifoaming agents, antioxidants, rust preventives, adhesion imparting agents, solvents and the like.
Only one type of these may be used, or two or more types may be used.

The curable composition described above is used by applying it to a substrate.

Here, the base material means a printed wiring board or flexible printed wiring board on which a circuit is formed in advance with copper or the like, a metal substrate, a glass substrate, a ceramic substrate, a wafer plate, a metal foil such as copper foil, a polyimide film, a polyester film, and polyethylene. Examples include films such as naphthalate (PEN) films, glass cloth, and fibers such as aramid fibers.

<<<Dry Film>>>
A dry film can be obtained, for example, by forming a resin layer by coating a curable composition on a polyethylene terephthalate film, drying the resin layer, and laminating a polypropylene film as necessary.

<<<cured product>>>
A cured product is obtained by curing the resin layer of the dry film described above.

The method for obtaining a cured product from the curable composition is not particularly limited, and can be changed as appropriate according to the composition of the curable composition. As an example, after performing the step of applying the curable composition onto the substrate as described above (for example, coating with an applicator or the like), a drying step of drying the curable composition is performed as necessary. Then, a thermosetting step of thermally cross-linking the polyphenylene ether by heating (for example, heating with an inert gas oven, hot plate, vacuum oven, vacuum press, etc.) may be performed. The implementation conditions (for example, coating thickness, drying temperature and time, heating temperature and time, etc.) in each step may be appropriately changed according to the composition, application, etc. of the curable composition.

<<<Electronic Components>>>
The electronic component has the cured product of the present embodiment described above, and has excellent dielectric properties and heat resistance, so that it can be used for various purposes.

Its use is not particularly limited, but preferred examples include large-capacity high-speed communication represented by fifth-generation communication systems (5G), millimeter-wave radar for automobile ADAS (advanced driving system), and the like.

EXAMPLES Hereinafter, the present embodiment will be described in more detail with examples and comparative examples, but the present embodiment is not limited to the following.

<<<Synthesis of Polyphenylene Ether>>>
<<Example 1>>
86.6 g of 2,6-dimethylphenol, 10.8 g of 2-allylphenol and 2.64 g of 2-methyl-6-tert-butylphenol were added to a 4 L separable flask and dissolved in 1175 g of toluene. Furthermore, 0.18 wt % of di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)]chloride (Cu/TMEDA) and 0.18 wt % of tetramethylethylenediamine (TMEDA) were added. The mixture was adjusted to 16 wt %, stirred with a stirring blade (paddle blade having a diameter of 12 cm), and reacted at 40° C. for 22 hours while blowing dry air into the reaction solution at a flow rate of 110 mL/min.
After completion of the reaction, di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper (II)] chloride (Cu/TMEDA) was removed by filtration, and 5.4 L of methanol: concentrated After reprecipitation with a mixed solution of 21 mL of hydrochloric acid and 122 mL of H ₂ O, the precipitate was filtered under reduced pressure, washed with methanol, and dried at 80° C. for 24 hours to obtain a polyphenylene ether according to Example 1.

<<Example 2-9, Comparative Example 1-3, Reference Example 1-5>>
Polyphenylene ethers according to Examples, Comparative Examples, and Reference Examples were obtained in the same manner as in Example 1, except that the raw material phenols used were changed to those shown in the table.

<<<evaluation>>>
Each polyphenylene ether was evaluated as follows. The evaluation results are shown in the table.

<<molecular weight>>
The number average molecular weight (Mn) and weight average molecular weight (Mw) of each polyphenylene ether were measured.

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

<<dielectric properties>>
2 g of each polyphenylene ether was dissolved in 7 g of cyclohexanone to form a varnish. Then, each polyphenylene ether varnish was applied to the shiny surface of a copper foil having a thickness of 18 μm so that the film thickness after drying was 30 μm, and dried in a hot air circulation drying oven at 90° C. for 30 minutes. Then, after curing in an inert oven at 200° C. for 1 hour, the copper foil was etched to obtain a coating film (measurement sample) of each composition.

The relative dielectric constant Dk and the dielectric loss tangent Df were measured by a SPDR (Split Post Dielectric Resonator) resonator method using a test piece obtained by cutting the prepared measurement sample into a length of 80 mm and a width of 45 mm. A vector-type network analyzer E5071C and an SPDR resonator manufactured by Keysight Technologies LLC were used as measuring instruments, and a calculation program manufactured by QWED was used. The conditions were a frequency of 10 GHz and a measurement temperature of 25°C.

Claims (6)

Obtained from a raw material phenol containing at least a phenol that satisfies the following condition 1 and a phenol that satisfies at least the following condition 2,
A polyphenylene ether in which the content of phenols satisfying condition 2 is 15 mol % or less relative to the total amount of raw material phenols.
(Condition 1)
Having hydrogen atoms at the ortho and para positions (Condition 2)
having a hydrogen atom at the para position and having a branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or a linear hydrocarbon group having 4 to 15 carbon atoms 2. The method according to claim 1, wherein the branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and/or the linear hydrocarbon group having 4 to 15 carbon atoms in the phenols satisfying condition 2 is a tert-butyl group. Polyphenylene ether. A curable composition comprising the polyphenylene ether of claim 1 or 2. A dry film having a resin layer comprising the curable composition according to claim 3 . A cured product of a resin layer comprising the curable composition according to claim 3 or the curable resin according to claim 4. An electronic component comprising the cured product according to claim 5 .