Polyphenylene ether, curable compositions containing polyphenylene ether, dry films, cured products, and electronic components

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

Technical Field

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

Background Art

[0002] With the spread of high-capacity high-speed communication represented by the fifth-generation communication system (5G) and millimeter-wave radars for automotive ADAS (Advanced Driving Assistance System), the high-frequencyization of signals in communication devices has been progressing.

[0003] However, when an epoxy resin or the like is used as a wiring board material, the relative dielectric constant (Dk) and dielectric tangent (Df) are not sufficiently low. Therefore, as the frequency increases, the transmission loss due to dielectric loss increases, causing problems such as signal attenuation and heat generation. Therefore, polyphenylene ether with excellent low dielectric properties has been used.

[0004] In addition, Non-Patent Document 1 proposes a polyphenylene ether in which an allyl group is introduced into the molecule of polyphenylene ether to improve heat resistance by making it a thermosetting resin.

[0005] However, polyphenylene ether has limited soluble solvents, and the polyphenylene ether obtained by the method of Non-Patent Document 1 also dissolves only in highly toxic solvents such as chloroform and toluene. Therefore, there is a problem that it is difficult to handle the resin varnish and manage solvent exposure in the process of forming and curing a coating film for wiring board applications.

Prior Art Documents

Non-Patent Documents

[0006]

Non-Patent Document 1

[0007] Under these circumstances, the present inventors have found that a branched polyphenylene ether synthesized from a specific phenol as a raw material has high solvent solubility (Japanese Patent Publication No. 2020-055999).

[0008] However, the branched polyphenylene ethers disclosed in the above-mentioned literature have more polymerization-reactive polymer ends compared to linear polyphenylene ethers, which leads to a problem where the grown polymers further polymerize (so-called coupling), causing a rapid increase in molecular weight. Therefore, controlling the molecular weight of the resulting polyphenylene ether within the desired range requires careful selection of raw materials and fine adjustment of manufacturing conditions, making it unsuitable for mass production in some cases.

[0009] Therefore, the present invention aims to provide a branched polyphenylene ether that not only has low dielectric properties and excellent solvent solubility, but also has an easily controllable molecular weight and is suitable for mass production. [Means for solving the problem]

[0010] The inventors of this invention have conducted diligent research and found that the above problem can be solved by polyphenylene ethers composed of raw material phenols having a specific structure. That is, the present invention is as follows.

[0011] The present invention is obtained from raw material phenols, which include phenols satisfying at least the following condition 1 and phenols satisfying at least the following condition 2. A polyphenylene ether having a phenol content of 15 mol% or less relative to the total amount of raw material phenols that satisfies condition 2 above. (Condition 1) It has hydrogen atoms in the ortho and para positions. (Condition 2) Having a hydrogen atom in the para position, and having a branched or cyclic hydrocarbon group with 3 to 15 carbon atoms, and / or a linear hydrocarbon group with 4 to 15 carbon atoms.

[0012] It is preferable that the branched or cyclic hydrocarbon group having 3 to 15 carbon atoms and / or the linear hydrocarbon group having 4 to 15 carbon atoms of the phenol that satisfies condition 2 above is a tert-butyl group.

[0013] The present invention may also be a curable composition containing the polyphenylene ether.

[0014] The present invention may also be a dry film having a resin layer made of the curable composition described above.

[0015] The present invention may also be a cured product of a resin layer made of the curable composition or the curable resin.

[0016] The present invention may also be an electronic component having the cured product. [Effects of the Invention]

[0017] According to the present invention, a branched polyphenylene ether is provided that not only has low dielectric properties and excellent solvent solubility, but is also easy to control the molecular weight and is suitable for mass production. [Modes for carrying out the invention]

[0018] The following describes the polyphenylene ether and curable compositions containing the polyphenylene ether of the present invention, but the present invention is not limited to the following.

[0019] When isomers exist in the described compounds, unless otherwise specified, all possible isomers can be used in the present invention.

[0020] In the present invention, unless otherwise specified, the "unsaturated carbon bond" refers to an ethylenic or acetylenic carbon-carbon multiple bond (double bond or triple bond). In the present invention, the functional group having an unsaturated carbon bond is not particularly limited, and examples include an alkenyl group (e.g., vinyl group, allyl group), an alkynyl group (e.g., ethynyl group), or a (meth)acryloyl group. In addition, the functional group having these unsaturated carbon bonds can have a carbon number of, for example, 15 or less, 10 or less, 8 or less, 5 or less, 3 or less, etc.

[0021] In the present invention, phenols that can be used as raw materials for polyphenylene ether (PPE) and can become constituent units of polyphenylene ether are collectively referred to as "raw material phenols".

[0022] In the present invention, when expressing "ortho position", "para position", etc. in the description of raw material phenols, unless otherwise specified, the position of the phenolic hydroxyl group is used as the reference (ipso position).

[0023] In the present invention, when simply expressing "ortho position", etc., it means "at least one of the ortho positions", etc. Therefore, unless otherwise contradictory, when simply referring to the "ortho position", it may be interpreted as indicating either one of the ortho positions or both of the ortho positions.

[0024] In this specification, although mainly monohydric phenols are disclosed as raw material phenols, polyhydric phenols may be used as raw material phenols as long as the effects of the present invention are not inhibited.

[0025] In this specification, when the upper limit value and the lower limit value of a numerical range are separately described, all combinations of each lower limit value and each upper limit value are substantially described within a non-contradictory range.

[0026] <<<Polyphenylene ether>>> The polyphenylene ether according to this embodiment is a polyphenylene ether obtained from raw material phenols that include at least phenols satisfying condition 1 below and at least phenols satisfying condition 2 below. (Condition 1) It has hydrogen atoms in the ortho and para positions. (Condition 2) Having a hydrogen atom in the para position, and having a branched or cyclic hydrocarbon group with 3 to 15 carbon atoms, and / or a linear hydrocarbon group with 4 to 15 carbon atoms.

[0027] The raw material phenols may also contain other phenols that do not satisfy conditions 1 and 2.

[0028] Here, the statement that the raw material phenols include phenols that satisfy at least condition 1 and phenols that satisfy at least condition 2 means that they fall under at least one of the following forms 1 and 2. (Form 1) The raw material phenols include at least phenols that satisfy both condition 1 and condition 2. (Form 2) The raw material phenols include at least phenols that satisfy condition 1 but not condition 2, and phenols that do not satisfy condition 1 but satisfy condition 2.

[0029] In Form 1, the raw material phenols may further contain phenols that satisfy condition 1 but not condition 2, and / or phenols that do not satisfy condition 1 but satisfy condition 2.

[0030] Hereinafter, branched or cyclic hydrocarbon groups having 3 to 15 carbon atoms, and / or linear hydrocarbon groups having 4 to 15 carbon atoms, that satisfy condition 2 may be simply referred to as "predetermined hydrocarbon groups." Note that the predetermined hydrocarbon groups may be hydrocarbon groups having both cyclic and branched structures.

[0031] <<Raw phenols>> <Phenols that satisfy condition 1> Phenols that satisfy condition 1 are phenols that have hydrogen atoms in the ortho and para positions.

[0032] Phenols that satisfy condition 1 may have one or more predetermined hydrocarbon groups. In this case, they become the raw material phenols of form 1 described above.

[0033] Phenols that satisfy condition 1 may have a functional group containing an unsaturated carbon bond.

[0034] Phenols that satisfy condition 1 are, for example, compounds represented by the following formula 1.

[0035] [ka]

[0036] In formula 1, R 11 ~R 13 Each of these is independently a hydrogen atom or a hydrocarbon group having 1 to 15 carbon atoms (preferably 1 to 4 carbon atoms).

[0037] Phenols that satisfy condition 1 include, specifically, 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, and 3-allyl-5-ethylphenol.

[0038] You may use only one type of phenol that satisfies condition 1, or you may use two or more types.

[0039] Phenols that satisfy condition 1 have a hydrogen atom at the ortho position, and therefore, when they undergo oxidative polymerization with phenols, ether bonds can be formed not only at the ipso and para positions, but also at the ortho position. As a result, polyphenylene ethers obtained using such phenols as raw materials can form branched chain structures.

[0040] Specifically, polyphenylene ethers obtained from phenols that satisfy condition 1 will have a structure in which part of the benzene ring is branched by ether bonds at least at the ipso, ortho, and para positions.

[0041] Polyphenylene ethers having a branched structure within their skeleton are called branched polyphenylene ethers. Such branched polyphenylene ethers offer excellent solubility in organic solvents.

[0042] The phenol content that satisfies condition 1 is preferably 1 mol% or more, 2 mol% or more, 5 mol% or more, or 8 mol% or more, relative to the total amount of raw material phenols, and also preferably 40 mol% or less, 30 mol% or less, 20 mol% or less, or 15 mol% or less.

[0043] The phenol content that satisfies condition 1 is calculated based on the total amount of phenol raw materials used in the synthesis of branched polyphenylene ether.

[0044] <Phenols that satisfy condition 2> Phenols that satisfy condition 2 are phenols having a hydrogen atom in the para position and having one or more (preferably one or two) branched or cyclic hydrocarbon groups having 3 to 15 carbon atoms, and / or linear hydrocarbon groups having 4 to 15 carbon atoms.

[0045] Phenols that satisfy condition 2 may have one or more linear hydrocarbon groups having 1 to 3 carbon atoms in addition to the specified hydrocarbon group.

[0046] Phenols that satisfy condition 2 may have a functional group containing an unsaturated carbon bond.

[0047] Phenols that satisfy condition 2 are, for example, compounds represented by the following formula 2.

[0048] [ka]

[0049] In formula 2, R 21 ~R 24 Each of these groups consists of at least one branched or cyclic hydrocarbon group having 3 to 15 carbon atoms, and / or a linear hydrocarbon group having 4 to 15 carbon atoms, with the remaining groups each independently being a hydrogen atom or a linear hydrocarbon group having 1 to 3 carbon atoms.

[0050] Branched or cyclic hydrocarbon groups having 3 to 15 carbon atoms, and / or linear hydrocarbon groups having 4 to 15 carbon atoms, are preferably saturated (without unsaturated carbon bonds) from the viewpoint of low dielectric properties.

[0051] Branched or cyclic hydrocarbon groups having 3 to 15 carbon atoms, and / or linear hydrocarbon groups having 4 to 15 carbon atoms, have a stronger effect of suppressing the increase in molecular weight of 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 balanced manner, branched or cyclic hydrocarbon groups having 3 to 15 carbon atoms, and / or linear hydrocarbon groups having 4 to 15 carbon atoms are preferred, branched or cyclic hydrocarbon groups having 3 to 10 carbon atoms, and / or linear hydrocarbon groups having 4 to 10 carbon atoms are more preferred, branched hydrocarbon groups having 3 to 6 carbon atoms, even more preferred, and branched hydrocarbon groups having 4 carbon atoms are particularly preferred. More specifically, tert-butyl groups are preferred.

[0052] Specifically, phenols that satisfy condition 2 include: Examples of phenols having branched hydrocarbon groups with 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, etc. Phenols having cyclic hydrocarbon groups with 3 to 15 carbon atoms include 2-phenylphenol, 3-phenylphenol, 2,6-diphenylphenol, 2,6-ditrylphenol, 2-allyl-6-phenylphenol, 2-allyl-6-styrylphenol, 2-methyl-6-styrylphenol, etc. Examples of phenols having a linear hydrocarbon group with 4 to 15 carbon atoms include 2-n-butylphenol, 3-n-butylphenol, and 2-dodecylphenol; These are some examples.

[0053] For phenols that satisfy condition 2, one type may be used, or two or more types may be used.

[0054] The phenol content that satisfies condition 2 is preferably 15 mol% or less relative to the total amount of raw material phenols.

[0055] Furthermore, the phenol content that satisfies condition 2 only needs to be greater than 0 mol% of the total amount of raw material phenols, and more specifically, it can be 0.1 mol% or more, 0.5 mol% or more, 1 mol% or more, or 2 mol% or more, etc.

[0056] The phenol content that satisfies condition 2 is calculated based on the total amount of phenol raw materials used in the synthesis of branched polyphenylene ether.

[0057] As described above, the polyphenylene ether of the present invention has a branched structure by containing phenols that satisfy condition 1 as raw material phenols. Compared to linear polyphenylene ethers, branched polyphenylene ethers have more polymer-reactive polymer ends. As a result, the grown polymers can further polymerize (so-called coupling), leading to a rapid increase in molecular weight, making reaction control difficult. Based on these findings, the present invention combines phenols satisfying condition 1 with phenols satisfying condition 2 in specific proportions as raw material phenols. This causes appropriate steric hindrance from predetermined hydrocarbon groups, suppressing the rapid molecular weight increase that occurs during the synthesis of branched polyphenylene ethers and facilitating reaction control. As a result, it is anticipated that polyphenylene ethers with predetermined molecular weights (particularly those satisfying industrially useful number-average molecular weights of 5,000 to 30,000 and / or weight-average molecular weights of 10,000 to 150,000) can be efficiently produced while maintaining the excellent performance derived from the branched structure.

[0058] On the other hand, the effect of suppressing the increase in molecular weight described above can also be obtained by phenols having an allyl group, such as 2-allyl-6-methylphenol, although not to the same extent as in the present invention. However, allyl groups worsen dielectric properties, and the cost of such raw material phenols tends to be high. According to the present invention, compared to the case in which molecular weight suppression is performed solely by phenols having an allyl group, a polyphenylene ether with superior dielectric properties and production costs can be obtained.

[0059] Here, phenols that satisfy condition 2 preferably have a linear hydrocarbon group with 3 or fewer carbon atoms (preferably a methyl group or an ethyl group, more preferably a methyl group) at both or one of the ortho positions (preferably at either one of the ortho positions). It is thought that by having such a structure for phenols that satisfy condition 2, steric hindrance can be further promoted within a range that does not easily affect various physical properties, and the molecular weight suppression effect can be further improved.

[0060] <Other phenols> In the present invention, other phenols other than the raw material phenols described above may be included, as long as they do not impair the effects of the invention. For example, phenols having a hydrogen atom at the para position, no hydrogen atom at the ortho position, and no predetermined hydrocarbon group (additional phenols) can be suitably used.

[0061] The additional phenols may have a hydrocarbon group with 3 or fewer carbon atoms, and may also have a functional group containing an unsaturated carbon bond.

[0062] Additional phenols are, for example, compounds represented by the following formula.

[0063] [ka]

[0064] In formula 3, R 31 , R 34Each of these is independently a linear hydrocarbon group having 1 to 3 carbon atoms, and R 32 , R 33 Each of these is independently a hydrogen atom or a hydrocarbon group having 1 to 3 carbon atoms.

[0065] 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, and 2-vinyl-6-ethylphenol.

[0066] The content of additional phenols can be 50 mol% or more, 60 mol% or more, 70 mol% or more, or 80 mol% or more, relative to the total amount of raw material phenols.

[0067] By including an appropriate amount of additional phenols along with phenols that satisfy condition 1 and phenols that satisfy condition 2, it becomes easier to control the reaction during the synthesis of polyphenylene ethers.

[0068] However, from the viewpoint of low dielectric properties and production costs, it is preferable that the content of additional phenols having allyl groups be less than 20 mol%, less than 10 mol%, less than 5 mol%, or less than 1 mol% relative to the total amount of raw material phenols.

[0069] Furthermore, the other phenols may include phenols other than the additional phenols (for example, phenols that do not have a hydrogen atom at the para position).

[0070] <Phenols containing functional groups with unsaturated carbon bonds> The raw material phenols (phenols that satisfy condition 1, phenols that satisfy condition 2, and other phenols) may have functional groups containing unsaturated carbon bonds.

[0071] By including phenols containing functional groups with unsaturated carbon bonds in the raw material phenols, unsaturated carbon bonds are introduced into the side chains of the resulting polyphenylene ether. Such polyphenylene ethers can undergo three-dimensional crosslinking through a curing reaction of these unsaturated carbon bonds, making them usable as curable polyphenylene ethers.

[0072] The content of raw material phenols containing functional groups with unsaturated carbon bonds can be set appropriately depending on the application, etc., but from the viewpoint of low dielectric properties, for example, it can be 0 mol%, 1 mol% or more, 2 mol% or more, 3 mol% or more, or 5 mol% or more relative to the total amount of raw material phenols, or it can be 99 mol% or less, 50 mol% or less, 30 mol% or less, or 20 mol% or less.

[0073] The content of raw material phenols containing functional groups with unsaturated carbon bonds is calculated based on the total amount of raw material phenols used in the synthesis of branched polyphenylene ethers.

[0074] <<Synthesis method>> The polyphenylene ether according to this embodiment can be synthesized by applying conventionally known methods for synthesizing polyphenylene ethers (polymerization conditions, presence or absence of catalyst, type of catalyst, etc.), except that the aforementioned raw material phenols are used.

[0075] Next, we will describe an example of a method for synthesizing polyphenylene ether.

[0076] Polyphenylene ethers can be synthesized, for example, by preparing a polymerization solution containing raw material phenols, a catalyst, and a solvent (polymerization solution preparation step), supplying oxygen to at least the solvent (oxygen supply step), and oxidative polymerization of the phenols in the polymerization solution containing oxygen (polymerization step).

[0077] The polymerization solution preparation step, the oxygen supply step, and the polymerization step will be described below. Each step may be performed continuously, or some or all of one step may be performed simultaneously with some or all of another step, or one step may be interrupted to perform another step. For example, the oxygen supply step may be performed during the polymerization solution preparation step or the polymerization step. Furthermore, this method for synthesizing polyphenylene ether may include other steps as needed. Other steps include, for example, a step for extracting the polyphenylene ether obtained by the polymerization step (e.g., a step of reprecipitation, filtration, and drying), and the modification step described above.

[0078] <Polymerization solution preparation process> The polymerization solution preparation step is a step in which the raw materials, including the phenols to be polymerized in the polymerization step described later, are mixed to prepare a polymerization solution. Examples of raw materials for the polymerization solution include raw phenols, a catalyst, and a solvent.

[0079] (catalyst) The catalyst is not particularly limited and can be any suitable catalyst used in the oxidative polymerization of polyphenylene ether.

[0080] Examples of catalysts include amine compounds and metal amine compounds consisting of heavy metal compounds such as copper, manganese, and cobalt, and amine compounds such as tetramethylethylenediamine. In particular, to obtain copolymers with a sufficient molecular weight, it is preferable to use copper-amine compounds in which a copper compound is coordinated to the amine compound. One type of catalyst may be used, or two or more types may be used.

[0081] The catalyst content is not particularly limited, but it should be approximately 0.1 to 0.6 mol% relative to the total amount of raw material phenols in the polymerization solution.

[0082] Such catalysts may be dissolved in a suitable solvent beforehand.

[0083] (solvent) The solvent is not particularly limited and may be any suitable solvent used in the oxidative polymerization of polyphenylene ether. Preferably, the solvent is one capable of dissolving or dispersing the phenolic compound and catalyst.

[0084] Examples of solvents 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); and diethylene glycol monoethyl ether acetate (CA). One solvent may be used, or two or more solvents may be used.

[0085] Furthermore, the solvent may include water or a water-compatible solvent.

[0086] The solvent content in the polymerization solution is not particularly limited and can be adjusted as appropriate.

[0087] (Other ingredients) The polymerization solution may contain other raw materials, as long as they do not impair the effects of this embodiment.

[0088] <Oxygen supply process> The oxygen supply process involves passing an oxygen-containing gas through the polymerization solution.

[0089] The oxygen gas ventilation time and the oxygen concentration in the oxygen-containing gas used can be adjusted as appropriate according to atmospheric pressure, temperature, etc.

[0090] <Polymerization process> The polymerization process involves oxidative polymerization of phenols in a polymerization solution under conditions where oxygen is supplied to the polymerization solution.

[0091] The specific polymerization conditions are not particularly limited, but for example, stirring at 25-100°C for 2-24 hours is sufficient. The stirring method is not particularly limited, and known methods (e.g., paddle blades) can be used.

[0092] <<<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. Furthermore, the polyphenylene ether according to this embodiment preferably has a weight-average molecular weight of 10,000 to 150,000. Moreover, the polyphenylene ether according to this 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, and particularly preferably 1.3 to 10.

[0093] By setting the molecular weight within this range, it is possible to improve the film-forming properties of the curable composition while maintaining solubility in the solvent.

[0094] In this embodiment, the number-average molecular weight and weight-average molecular weight were measured by gel permeation chromatography (GPC) and obtained by conversion using a calibration curve prepared with standard polystyrene.

[0095] <<<Curable composition>>> The branched polyphenylene ether according to this embodiment can be combined with known components to form a curable composition.

[0096] Known components include, for example, silica, peroxides, crosslinking curing agents, maleimide compounds, and elastomers. Other known components include flame retardant enhancers (phosphorus compounds, etc.), cellulose nanofibers, polymer components (cyanate ester resins, epoxy resins, phenol novolac resins, and other resin components; polyimides, polyamides, and other organic polymers), dispersants, thermosetting catalysts, thickeners, defoamers, antioxidants, rust inhibitors, adhesion enhancers, and solvents. These may be used individually or in combination of two or more types.

[0097] The curable composition described above is used by being applied to a substrate.

[0098] Here, the term "substrate" refers to printed circuit boards and flexible printed circuit boards with circuits already formed from copper or the like, metal substrates, glass substrates, ceramic substrates, wafers, metal foils such as copper foil, films such as polyimide film, polyester film, and polyethylene naphthalate (PEN) film, and fibers such as glass cloth and aramid fiber.

[0099] <<<Dry Film>>> A dry film can be obtained, for example, by forming a resin layer on a polyethylene terephthalate film by coating and drying a curable composition, and then laminating a polypropylene film as needed.

[0100] <<<Cured product>>> The cured product is obtained by curing the resin layer of the dry film described above.

[0101] The method for obtaining a cured product from a curable composition is not particularly limited and can be appropriately modified depending on the composition of the curable composition. As an example, after performing the step of coating the curable composition onto a substrate as described above (e.g., coating with an applicator), a drying step may be performed to dry the curable composition as needed, and then a thermosetting step may be performed to thermally crosslink the polyphenylene ether by heating (e.g., heating with an inert gas oven, hot plate, vacuum oven, vacuum press, etc.). The conditions for each step (e.g., coating thickness, drying temperature and time, heating temperature and time, etc.) may be appropriately modified depending on the composition of the curable composition and its intended use.

[0102] <<<Electronic Components>>> The electronic component has the cured product of the aforementioned embodiment and possesses excellent dielectric properties and heat resistance, making it suitable for a variety of applications.

[0103] While its applications are not particularly limited, preferred applications include high-capacity, high-speed communication such as fifth-generation communication systems (5G) and millimeter-wave radar for automotive ADAS (Advanced Driver-Assistance Systems). [Examples]

[0104] The embodiment will be described in more detail below with reference to examples and comparative examples, but this embodiment is not limited to the following.

[0105] <<<Synthesis of Polyphenylene Ether>>> <<Example 1>> In a 4L separable flask, 86.6g of 2,6-dimethylphenol, 10.8g of 2-allylphenol, and 2.64g of 2-methyl-6-tert-butylphenol were added and dissolved in 1175g of toluene. The mixture was then adjusted to contain 0.18wt% di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) and 0.16wt% tetramethylethylenediamine (TMEDA). The mixture was stirred with a 12cm diameter paddle blade and reacted at 40°C for 22 hours while blowing dry air into the reaction mixture at a flow rate of 110mL / min. After the reaction was complete, di-μ-hydroxo-bis[(N,N,N',N'-tetramethylethylenediamine)copper(II)] chloride (Cu / TMEDA) was removed by filtration, reprecipitation was performed with a mixture of 5.4 L methanol, 21 mL concentrated hydrochloric acid, and 122 mL H2O, and the solution was removed by vacuum filtration. After washing with methanol, the solution was dried at 80°C for 24 hours to obtain the polyphenylene ether according to Example 1.

[0106] <<Examples 2-9, Comparative Examples 1-3, Reference Examples 1-5>> Except for changing the raw material phenols used as shown in the table, polyphenylene ethers according to each example, comparative example, and reference example were obtained in the same manner as in Example 1.

[0107] <<<Rating>>> The following evaluations were performed on each polyphenylene ether. The evaluation results are shown in the table.

[0108] <<Molecular weight>> The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of each polyphenylene ether were measured.

[0109] The number-average molecular weight (Mn) and weight-average molecular weight (Mw) of polyphenylene ether were determined by gel permeation chromatography (GPC). In the GPC, a Shodex K-805L column was used, with a column temperature of 40°C, a flow rate of 1 mL / min, chloroform as the eluent, and polystyrene as the standard substance.

[0110] <<Dielectric Properties>> Two g of each polyphenylene ether was dissolved in seven g of cyclohexanone to form a varnish. Next, each polyphenylene ether varnish was applied to the shine surface of an 18 μm thick copper foil so that the film thickness after drying was 30 μm, and dried in a hot air circulating drying oven at 90°C for 30 minutes. After curing in an inert oven at 200°C for 1 hour, the copper foil was etched to obtain coating films (measurement samples) consisting of each composition.

[0111] The prepared measurement samples were cut into 80 mm long and 45 mm wide pieces, and the relative permittivity Dk and dielectric loss tangent Df were measured using the SPDR (Split Post Dielectric Resonator) method. The measurement equipment used was a Keysight Technologies LLC E5071C vector network analyzer, an SPDR resonator, and a calculation program from QWED. The conditions were a frequency of 10 GHz and a measurement temperature of 25°C.

[0112] [Table 1]

[0113] [Table 2]

Claims

1. Obtained from raw material phenols, which include phenols satisfying at least condition 1 below and phenols satisfying at least condition 2 below. The content of phenols that satisfy condition 2 above is 15 mol% or less relative to the total amount of raw material phenols. The content of phenols satisfying condition 1 above is 40 mol% or less relative to the total amount of raw material phenols. A polyphenylene ether in which the phenols satisfying condition 2 include one or more selected from 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-diisobutenylphenol, and 2,6-diisopentenylphenol. (Condition 1) It has hydrogen atoms in the ortho and para positions. (Condition 2) It has a hydrogen atom in the para position and a branched hydrocarbon group having 3 to 15 carbon atoms.

2. The polyphenylene ether according to claim 1, wherein the branched hydrocarbon group of the phenol that satisfies condition 2 above is a tert-butyl group.

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

4. A dry film having a resin layer made of the curable composition according to claim 3.

5. A cured resin layer made of the curable composition according to claim 3 or the curable resin according to claim 4.

6. An electronic component having the cured product described in claim 5.

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