Polyphenylene ether, its production method, thermosetting composition, prepreg, and laminate

Abstract

The purpose of the present invention is to provide a polyphenylene ether excelling in solubility into general-purpose aromatic solvents and general-purpose ketone solvents, and a production method therefor.　Provided are a polyphenylene ether including a repeating unit derived from a phenol of formula (1), a production method therefor, a thermosetting composition, a prepreg, and a multilayer body.

Description

[Technical field]

[0001] The present invention relates to polyphenylene ether, a method for producing the same, a thermosetting composition, a prepreg, and a laminate. [Background technology]

[0002] Polyphenylene ether (hereinafter, also referred to as "PPE") has excellent high-frequency characteristics, flame retardancy, and heat resistance, and is therefore widely used as a material for products and parts in the electrical and electronics, automotive, and food and packaging fields, as well as in various other industrial materials. In particular, in recent years, its low dielectric properties and heat resistance have been utilized to promote its application as a modifier in electronic materials such as substrate materials and in various other applications.

[0003] However, although high molecular weight polyphenylene ethers having repeating units derived from monohydric phenols, typically typified by 2,6-dimethylphenol, dissolve in highly toxic solvents such as chloroform, they have the problem that they are poorly soluble at high concentrations at room temperature in aromatic solvents such as toluene, which are known to be good solvents, and are insoluble in ketone solvents such as methyl ethyl ketone. For this reason, for example, when used as a wiring board material, it is difficult to handle resin varnish solutions in toluene, methyl ethyl ketone, etc.

[0004] Patent Document 1 discloses that polyphenylene ether having a low molecular weight and a specific particle size has excellent solubility in solvents such as methyl ethyl ketone. Furthermore, Patent Document 2 describes a modified polyphenylene ether compound having a specific polyphenylene ether moiety in its molecular structure and having at least one p-ethenylbenzyl group, m-ethenylbenzyl group, or the like at the molecular end. Furthermore, Patent Document 3 describes a modified polymer having a polyphenylene ether portion in its molecular structure and having a methacryl group at the molecular end. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2004-99824 A [Patent Document 2] JP 2004-339328 A [Patent Document 3] Special Publication No. 2008-510059 Summary of the Invention [Problem to be solved by the invention]

[0006] As mentioned above, Patent Documents 1-3 disclose methods for producing polyphenylene ethers with low molecular weights in order to improve the solvent solubility of polyphenylene ethers, but the solubility at room temperature in general-purpose ketone solvents such as methyl ethyl ketone is not significantly improved by simply lowering the molecular weight of polyphenylene ether, and is still insufficient, so that a method for improving the long-term solvent solubility in ketone solvents is desired. In addition, the development of polyphenylene ethers that have excellent solubility in toluene at room temperature even when they have a high molecular weight is desired.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a polyphenylene ether having excellent solubility in general-purpose solvents and a method for producing the same. [Means for solving the problem]

[0008] That is, the present invention is as follows. [1] A polyphenylene ether comprising repeat units derived from a phenol of formula (1). [ka] ...Equation (1) (In formula (1), R 13 represents an optionally substituted saturated or unsaturated hydrocarbon group having 15 carbon atoms; R 11 and R 12are each independently a hydrogen atom, a linear saturated hydrocarbon group having 1 to 12 carbon atoms, or a substituent represented by the following formula (3), 11 and R 12 Both of are not hydrogen atoms at the same time.) [ka] ...Equation (3) (In formula (3), R 31 are each independently a linear alkyl group having 1 to 8 carbon atoms which may be substituted, or two R 31 The atoms contained therein are bonded to each other to form a cyclic alkyl group having 1 to 8 carbon atoms, and R 32 each independently represents an optionally substituted alkylene group having 1 to 8 carbon atoms; each b independently represents 0 or 1; R 33 is a hydrogen atom, an optionally substituted alkyl group having 1 to 8 carbon atoms, or an optionally substituted phenyl group. [2] The polyphenylene ether according to [1], which contains a repeating unit derived from a phenol represented by the above formula (1) and a repeating unit derived from a phenol represented by the following formula (2): [ka] ...Equation (2) (In formula (2), R 21 each independently represents an optionally substituted saturated hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom; R 22 are each independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom. [3] The polyphenylene ether according to [2], comprising 0.1 to 100 mol % of the repeating unit derived from phenol of the formula (1) and 0 to 99.9 mol % of the repeating unit derived from phenol of the formula (2), relative to 100 mol % in total of the repeating unit derived from phenol of the formula (1) and the repeating unit derived from phenol of the formula (2). [4] The polyphenylene ether according to [3], comprising 20 to 100 mol % of the repeating unit derived from a phenol represented by the formula (1) and 0 to 80 mol % of the repeating unit derived from a phenol represented by the formula (2), relative to 100 mol % in total of the repeating unit derived from a phenol represented by the formula (1) and the repeating unit derived from a phenol represented by the formula (2). [5] The polyphenylene ether according to any one of [1] to [4], which has a reduced viscosity (ηsp / c) of 0.03 to 0.90 dL / g as measured at 30°C in a chloroform solution having a concentration of 0.5 g / dL using an Ubbelohde viscometer. [6] R 11 is a t-butyl group, and the R 12 The polyphenylene ether according to any one of [1] to [5], wherein [7] A method for producing polyphenylene ether according to any one of [1] to [6], comprising a step of oxidatively polymerizing a phenol represented by the formula (1). [8] A thermosetting composition comprising the polyphenylene ether according to any one of [1] to [6]. [9] A prepreg comprising a substrate and the thermosetting composition according to [8].

[10] The prepreg according to [9], wherein the base material is glass cloth.

[11] A laminate comprising a cured product of the prepreg according to [9] or

[10] and a metal foil. Effect of the Invention

[0009] According to the present invention, it is possible to provide a polyphenylene ether having excellent solubility in aromatic solvents and ketone solvents, a method for producing the same, and a thermosetting composition, a prepreg, and a laminate using the polyphenylene ether. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment for carrying out the present invention (hereinafter, referred to as "the present embodiment") will be described in detail. The following embodiment is an example for explaining the present invention, and the present invention is not limited to only this embodiment, and the present invention can be carried out by appropriately modifying it within the scope of the gist of the present invention.

[0011] In the present embodiment, polyphenylene ether in which some or all of the hydroxyl groups contained in the polyphenylene ether have been modified may be simply referred to as "polyphenylene ether". Therefore, when the term "polyphenylene ether" is used, it includes both unmodified polyphenylene ether and modified polyphenylene ether, unless there is a particular contradiction. In this specification, A (numeric value) to B (numeric value) means A or more and B or less.

[0012] <Polyphenylene ether> The polyphenylene ether of the present embodiment contains a repeating unit derived from phenol represented by the following formula (1). [ka] ...Equation (1) (In formula (1), R 13 represents an optionally substituted saturated or unsaturated hydrocarbon group having 15 carbon atoms; R 11 and R 12 are each independently a hydrogen atom, a linear saturated hydrocarbon group having 1 to 12 carbon atoms, or a substituent represented by the following formula (3), 11 and R 12 Both of are not hydrogen atoms at the same time.) In formula (1), R 11 and R 12 are each independently at least one selected from the group consisting of a hydrogen atom, a linear saturated hydrocarbon group having 1 to 12 carbon atoms, and a substituent represented by formula (3). 11 and R 12 Both of R are not hydrogen atoms at the same time. 11 and R 12are each independently more preferably selected from a hydrogen atom, a methyl group, an ethyl group, and a substituent represented by formula (3). 11 is selected from the substituents represented by formula (3), R 12 is a hydrogen atom.

[0013] [ka] ...Equation (3) (In formula (3), R 31 are each independently a linear alkyl group having 1 to 8 carbon atoms which may be substituted, or two R 31 The atoms contained therein are bonded to each other to form a cyclic alkyl group having 1 to 8 carbon atoms, and R 32 each independently represents an optionally substituted alkylene group having 1 to 8 carbon atoms; each b independently represents 0 or 1; R 33 is a hydrogen atom, an optionally substituted alkyl group having 1 to 8 carbon atoms, or an optionally substituted phenyl group. The substituent represented by formula (3) is preferably a group containing a secondary and / or tertiary carbon, such as an isopropyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a tert-amyl group, a 2,2-dimethylpropyl group, a cyclohexyl group, or a group in which the hydrogen of the terminal hydrocarbon group in these groups is substituted with a phenyl group, more preferably a tert-butyl group or a cyclohexyl group, and even more preferably a tert-butyl group. The atoms contained therein may be bonded to each other to form a cyclic structure.

[0014] In this embodiment, in formula (1), R 11 is a t-butyl group, and R 12 is preferably a hydrogen atom.

[0015] In formula (1), R 13 is an optionally substituted saturated or unsaturated hydrocarbon group having 15 carbon atoms, and more preferably, R 13 C 15 H 31-2nwhere each n is independently an integer of 0 to 3.

[0016] Furthermore, the polyphenylene ether of the present embodiment may contain a repeating unit derived from a phenol of formula (2), in addition to the repeating unit derived from a phenol of formula (1). [ka] ...Equation (2) (In formula (2), R 21 each independently represents an optionally substituted saturated hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom; R 22 are each independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom.

[0017] In formula (2), R 21 are each independently preferably a saturated hydrocarbon group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, more preferably a methyl group or a phenyl group, and further preferably a methyl group. 21 Preferably, both have the same structure.

[0018] In formula (2), R 22 are each independently preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a methyl group. 22 may be the same or different, and preferred embodiments include an embodiment in which both are hydrogen atoms, and an embodiment in which one is a hydrogen atom and the other is a hydrocarbon group having 1 to 6 carbon atoms (preferably a methyl group).

[0019] In this embodiment, the structure of the polyphenylene ether can be identified by analyzing the polyphenylene ether by techniques such as NMR and mass spectrometry. A specific method for identifying the structure of polyphenylene ether is to carry out field desorption mass spectrometry (FD-MS), which is known to be less prone to fragmentation, and it is possible to estimate the repeating units from the intervals between the detected ions. In addition, there is a method for estimating the structure of polyphenylene ether by combining peak analysis of fragment ions using electron ionization (EI) and structural analysis by NMR. 1 It can be determined using analytical techniques such as H NMR. More specifically, the structure of the polyphenylene ether can be identified by the method described in the Examples below.

[0020] The polyphenylene ether of the present embodiment preferably contains 0.1 to 100 mol % of the repeating units derived from phenol of the above formula (1) and 0 to 99.9 mol % of the repeating units derived from phenol of the above formula (2) relative to 100 mol % in total of the repeating units derived from phenol of the above formula (1) and the repeating units derived from phenol of the above formula (2).

[0021] From the viewpoint of improving solubility in solvents, the repeating unit derived from phenol of the above formula (1) is preferably 0.1 mol% or more, more preferably 1 mol% or more, and even more preferably 20 mol% or more, based on the total 100 mol% of the repeating unit derived from phenol of the above formula (1) and the repeating unit derived from phenol of the above formula (2). When the repeating unit derived from phenol of the above formula (1) is contained at 20 mol% or more, in addition to improving the solubility in aromatic solvents, the solubility in ketone solvents and the like in which conventional polyphenylene ethers were insoluble also tends to improve. The repeating units derived from phenol of the above formula (2) are preferably 99.9 mol% or less, more preferably 99 mol% or less, and even more preferably 80 mol% or less, relative to the total 100 mol% of the repeating units derived from phenol of the above formula (1) and the repeating units derived from phenol of the above formula (2).

[0022] The content of the repeating unit derived from the phenol of the above formula (2) can be appropriately selected depending on the application. For example, when heat resistance is required for a substrate material, etc., it is preferable that the repeating unit derived from the phenol of the above formula (2) is as large as possible within the range in which the solvent solubility is maintained.

[0023] In this embodiment, the total molar ratio of the repeating units derived from phenol of the above formula (1) and the repeating units derived from phenol of the above formula (2) relative to 100 mol% of the polyphenylene ether is preferably 60 mol% or more, more preferably 80 mol% or more, and even more preferably 95 mol% or more, and may be 100 mol%.

[0024] The molar ratio of the repeating unit derived from phenol of the above formula (1) and the repeating unit derived from phenol of the above formula (2) to the total of 100 mol % of the repeating unit derived from phenol of the above formula (1) and the repeating unit derived from phenol of the above formula (2) is, for example, 1 H-NMR, 13 It can be determined using an analytical technique such as C-NMR, and more specifically, it can be measured by the method described in the Examples below.

[0025] Since the phenol of the above formula (2) does not have an unsubstituted ortho position (i.e., the two carbon atoms at the ortho positions relative to the carbon atom to which the hydroxyl group is bonded do not have hydrogen atoms bonded), it can react with another phenolic monomer predominantly at the carbon atoms at the para positions to the phenolic hydroxyl group. Thus, the repeating unit derived from the phenol of the above formula (2) includes a repeating unit having the structure of the following formula (4). [ka] ...Equation (4) (In formula (4), R 21 and R 22 is R in Eq. (2) 21 and R 22 is the same as

[0026] The content of the repeating unit having the structure of formula (4) in the repeating unit derived from the phenol of formula (2) on a molar basis is preferably 90% or more, more preferably 95% or more, even more preferably 99%, and may be 100%.

[0027] On the other hand, R of phenol in the above formula (1) 11 and R 12 are each independently a hydrogen atom, a linear saturated hydrocarbon group having 1 to 12 carbon atoms, or a substituent represented by the above formula (3) (wherein R 11 and R 12 (both of which are not hydrogen atoms at the same time), R 11 and R 12 When either one of the above is a hydrogen atom, in addition to the phenolic hydroxyl group, the repeating unit derived from the phenol may react with another phenolic monomer at either the ortho- or para-position of the phenol. Thus, the repeating unit derived from the phenol of the above formula (1) contains at least one selected from the group consisting of a structural unit of the following formula (5), a structural unit of the following formula (6), and a structural unit of the following formula (7). [ka] ...Equation (5) [ka] ...Equation (6) [ka] ...Equation (7) (R in Equation (5), Equation (6), and Equation (7) 11 , R 12 , R 13 is R in Eq. (1). 11 , R 12 , R 13 is the same as

[0028] In the repeating units derived from the phenol of the formula (1), the total content on a molar basis of the structural units of the formula (5), the structural units of the formula (6) and the structural units of the formula (7) is preferably 90% or more, more preferably 95% or more, even more preferably 99%, and may be 100%.

[0029] The reduced viscosity (ηsp / c) of the polyphenylene ether in this embodiment, measured using a Ubbelohde viscometer in a chloroform solution having a concentration of 0.5 g / dL at 30° C., is preferably 0.03 to 0.90 dL / g, more preferably 0.05 to 0.60 dL / g. The upper limit of the reduced viscosity may be 0.60 dL / g or less, or 0.40 dL / g or less. The reduced viscosity can be appropriately selected depending on the application. For example, in order to improve the fluidity when dissolved in a solvent for preparing a varnish in a process of applying the composition to a substrate material, a low reduced viscosity is preferable. The reduced viscosity can be measured by the method described in the Examples below.

[0030] The polyphenylene ether in this embodiment may have at least one partial structure selected from the group consisting of a partial structure of the following formula (8), a partial structure of the following formula (9), a partial structure of the following formula (10), and a partial structure of the following formula (11). [ka] (8) [ka] (9) [ka] (10) (In formula (10), R 4 is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated hydrocarbon is R 4 may have a substituent within the range of a total carbon number of 1 to 10.) [ka] (11) (In formula (11), R 5 is a saturated or unsaturated divalent hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated divalent hydrocarbon is R 5 may have a substituent within a range in which the total carbon number of R is 1 to 10; 6 is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated hydrocarbon is R 6 may have a substituent within the range of a total carbon number of 1 to 10.)

[0031] At least one partial structure selected from the group consisting of the partial structure of formula (8), the partial structure of formula (9), the partial structure of formula (10), and the partial structure of formula (11) may be introduced by a modification step described later, and may be directly bonded to an oxygen atom of a hydroxyl group contained in the polyphenylene ether.

[0032] <Production method of polyphenylene ether> The polyphenylene ether of the present embodiment can be obtained, for example, by a method including at least a step of oxidatively polymerizing a monovalent raw material phenol containing the phenol of the above formula (1). The step of oxidatively polymerizing is preferably a step of oxidatively polymerizing raw material phenols containing the phenol of the above formula (1) and the phenol of the above formula (2).

[0033] Examples of the phenol of formula (1) include 3-pentadecylphenol, commercially available cardanol, modified 3-pentadecylphenol obtained by introducing a linear saturated hydrocarbon group having 1 to 12 carbon atoms or a substituent represented by formula (3) into 3-pentadecylphenol, and modified cardanol obtained by introducing a linear saturated hydrocarbon group having 1 to 12 carbon atoms or a substituent represented by formula (3) into commercially available cardanol. The substituent to be introduced into 3-pentadecylphenol or commercially available cardanol is R 11 By introducing a bulky substituent such as a tert-butyl group or a cyclohexyl group into R11 and R 12 It is preferable to introduce a methyl group into both R 11 and R 12 Examples of a method for introducing a substituent into include A) a method of reacting with an alkyl halide in the presence of a Lewis acid, and B) a method of reacting with isobutene or the like in the presence of a Bronsted acid. The phenol of the formula (1) may be used alone or in combination of two or more kinds.

[0034] Examples of the phenol of the formula (2) include 2,6-dimethylphenol, 2-methyl-6-ethylphenol, 2,6-diethylphenol, 2-ethyl-6-n-propylphenol, 2-methyl-6-chlorophenol, 2-methyl-6-bromophenol, 2-methyl-6-n-propylphenol, 2-ethyl-6-bromophenol, 2-methyl-6-n-butylphenol, 2,6-di-n-propylphenol, 2-ethyl-6-chlorophenol, 2-methyl-6-phenylphenol, 2,6-diphenylphenol, 2-methyl-6-tolylphenol, 2,6-ditolylphenol, 2,3,6-trimethylphenol, 2,3-diethyl-6-n-propylphenol, 2,3,6-tributylphenol, 2,6-di-n-butyl-3-methylphenol, 2,6-dimethyl-3-n-butylphenol, and 2,6-dimethyl-3-t-butylphenol. Among these, 2,6-dimethylphenol, 2,3,6-trimethylphenol, and 2,6-diphenylphenol are particularly preferable since they are inexpensive and easily available. The phenol of the formula (2) may be used alone or in combination of two or more kinds.

[0035] (Oxidative polymerization process) Here, in the method for producing polyphenylene ether, an aromatic solvent that is a good solvent for polyphenylene ether can be used as the polymerization solvent in the oxidative polymerization step. Here, a good solvent for polyphenylene ether is a solvent capable of dissolving polyphenylene ether. Examples of such solvents include aromatic hydrocarbons such as benzene, toluene, xylene (including o-, m-, and p-isomers) and ethylbenzene; halogenated hydrocarbons such as chlorobenzene and dichlorobenzene; and nitro compounds such as nitrobenzene.

[0036] As the polymerization catalyst used in this embodiment, a known catalyst system that can be generally used for the production of polyphenylene ether can be used. A generally known catalyst system is one that is composed of a transition metal ion having redox ability and an amine compound that can form a complex with the transition metal ion, such as a catalyst system composed of a copper compound and an amine compound, a catalyst system composed of a manganese compound and an amine compound, a catalyst system composed of a cobalt compound and an amine compound, etc. Since the polymerization reaction proceeds efficiently under slightly alkaline conditions, a small amount of alkali or an additional amine compound may be added thereto.

[0037] The polymerization catalyst preferably used in the present embodiment is a catalyst containing a copper compound, a halogen compound, and an amine compound as catalyst components, and more preferably a catalyst containing a diamine compound represented by the following formula (12) as the amine compound.

[0038] [ka] ...Equation (12) (In formula (12), R 14 , R 15 , R 16 , R 17 are each independently a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms, but are not all hydrogen atoms at the same time. 18 is a linear or methyl-branched alkylene group having 2 to 5 carbon atoms.

[0039] Examples of the copper compound of the catalyst component described herein are listed below. Suitable copper compounds include cuprous compounds, cupric compounds, and mixtures thereof. Examples of cupric compounds include, for example, cupric chloride, cupric bromide, cupric sulfate, and cupric nitrate. Examples of cuprous compounds include, for example, cuprous chloride, cuprous bromide, cuprous sulfate, and cuprous nitrate. Particularly preferred metal compounds among these are cuprous chloride, cupric chloride, cuprous bromide, and cupric bromide. These copper salts may be synthesized at the time of use from oxides (e.g., cuprous oxide), carbonates, hydroxides, and the like and corresponding halogens or acids. A method that is often used is to mix the cuprous oxide exemplified above with hydrogen halide (or a solution of hydrogen halide) to prepare the copper salt.

[0040] Examples of halogen compounds include hydrogen chloride, hydrogen bromide, hydrogen iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, tetraethylammonium chloride, tetraethylammonium bromide, and tetraethylammonium iodide. These compounds can be used as aqueous solutions or solutions using appropriate solvents. These halogen compounds can be used alone as components, or in combination of two or more. Preferred halogen compounds are aqueous solutions of hydrogen chloride and hydrogen bromide.

[0041] The amount of these compounds used is not particularly limited, but is preferably 2 to 20 times the number of moles of halogen atoms relative to the number of moles of copper atoms, and the amount of copper atoms used is preferably in the range of 0.02 to 0.6 moles per 100 moles of the phenol compound added to the polymerization reaction.

[0042] Examples of the diamine compound of the catalyst component are as follows: N,N,N',N'-tetramethylethylenediamine, N,N,N'-trimethylethylenediamine, N,N'-dimethylethylenediamine, N,N-dimethylethylenediamine, N-methylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N'-triethylethylenediamine, N,N'-diethylethylenediamine, N,N-diethylethylenediamine, N-ethylethylenediamine, N,N-dimethyl-N'-ethylethylenediamine, N,N'-dimethyl-N-ethylethylenediamine, Nn-propylethylenediamine, N,N'-n-propylethylenediamine, Ni-propylethylenediamine, N,N'-i-propylethylenediamine, Nn-butylethylenediamine, amine, N,N'-n-butylethylenediamine, Ni-butylethylenediamine, N,N'-i-butylethylenediamine, Nt-butylethylenediamine, N,N'-t-butylethylenediamine, N,N,N',N'-tetramethyl-1,3-diaminopropane, N,N,N'-trimethyl-1,3-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N-methyl-1,3-diaminopropane, N,N,N',N'-tetramethyl-1,3-diamino-1-methylpropane, N,N,N',N'-tetramethyl-1,3-diamino-2-methylpropane, N,N,N',N'-tetramethyl-1,4-diaminobutane, and N,N,N',N'-tetramethyl-1,5-diaminopentane. A preferred diamine compound for this embodiment is one in which the number of carbon atoms in the alkylene group connecting the two nitrogen atoms is 2 or 3. The amount of these diamine compounds used is not particularly limited, but is preferably in the range of 0.01 mol to 10 mol per 100 mol of the phenol compound added to the polymerization reaction.

[0043] In this embodiment, the polymerization catalyst may contain a primary amine and a secondary monoamine as a component. Examples of the secondary monoamine include, but are not limited to, dimethylamine, diethylamine, di-n-propylamine, di-i-propylamine, di-n-butylamine, di-i-butylamine, di-t-butylamine, dipentylamines, dihexylamines, dioctylamines, didecylamines, dibenzylamines, methylethylamine, methylpropylamine, methylbutylamine, cyclohexylamine, N-phenylmethanolamine, N-phenylethanolamine, N-phenylpropanolamine, N-(m-methylphenyl)ethanolamine, N-(p-methylphenyl)ethanolamine, N-(2',6'-dimethylphenyl)ethanolamine, N-(p-chlorophenyl)ethanolamine, N-ethylaniline, N-butylaniline, N-methyl-2-methylaniline, N-methyl-2,6-dimethylaniline, and diphenylamine.

[0044] The polymerization catalyst of the present embodiment may also contain a tertiary monoamine compound as a component thereof. The tertiary monoamine compound is an aliphatic tertiary amine including an alicyclic tertiary amine. Examples of the tertiary monoamine compound include trimethylamine, triethylamine, tripropylamine, tributylamine, triisobutylamine, dimethylethylamine, dimethylpropylamine, allyldiethylamine, dimethyl-n-butylamine, diethylisopropylamine, and N-methylcyclohexylamine. These tertiary monoamines may be used alone or in combination of two or more. The amount of these compounds used is not particularly limited, but is preferably in the range of 15 moles or less relative to 100 moles of the phenol compound added to the polymerization reaction.

[0045] In this embodiment, there is no limitation on adding a surfactant that has been known to have an effect of improving polymerization activity. Examples of such surfactants include trioctylmethylammonium chloride, known under the trade names Aliquat 336 and Capriquat. The amount of the surfactant used is preferably within a range not exceeding 0.1% by mass relative to the total amount (100% by mass) of the polymerization reaction mixture.

[0046] As the oxygen-containing gas in the polymerization of this embodiment, in addition to pure oxygen, a mixture of oxygen and an inert gas such as nitrogen in any ratio, air, or a mixture of air and an inert gas such as nitrogen in any ratio can be used. Normal pressure is sufficient for the pressure in the system during the polymerization reaction, but reduced or increased pressure can be used as necessary.

[0047] The polymerization temperature is not particularly limited, but if it is too low, the reaction does not proceed easily, and if it is too high, the reaction selectivity may decrease or gel may be formed, so it is in the range of 0 to 60°C, preferably 10 to 40°C.

[0048] In the process for producing polyphenylene ether, the polymerization can also be carried out in a poor solvent such as an alcohol.

[0049] (Copper extraction and by-product removal process) In this embodiment, there is no particular restriction on the post-treatment method after the polymerization reaction is completed. Usually, an acid such as hydrochloric acid or acetic acid, or ethylenediaminetetraacetic acid (EDTA) and its salts, nitrilotriacetic acid and its salts, etc. are added to the reaction liquid to deactivate the catalyst. In addition, a method for removing and treating the dihydric phenol by-product generated by the polymerization of polyphenylene ether can be performed using a conventionally known method. If the metal ions, which are the catalyst, are substantially deactivated as described above, the mixture can be decolorized simply by heating it. Alternatively, a method of adding a required amount of a known reducing agent is also possible. Examples of known reducing agents include hydroquinone and sodium dithionite.

[0050] (Liquid-liquid separation process) In the method for producing polyphenylene ether, water may be added to extract the compound that has deactivated the copper catalyst, and then liquid-liquid separation may be performed into an organic phase and an aqueous phase, and the aqueous phase may be removed to remove the copper catalyst from the organic phase. This liquid-liquid separation step is not particularly limited, and may include methods such as static separation and separation using a centrifuge. In order to promote the liquid-liquid separation, a known surfactant or the like may be used.

[0051] (concentration / drying process) Next, in the method for producing polyphenylene ether of the present embodiment, the organic phase containing the polyphenylene ether after liquid-liquid separation may be concentrated and dried by volatilizing the solvent.

[0052] The method for volatilizing the solvent contained in the organic phase is not particularly limited, but examples thereof include a method of transferring the organic phase to a high-temperature concentration tank and distilling off the solvent to concentrate it, and a method of distilling off toluene using equipment such as a rotary evaporator to concentrate it, and the like.

[0053] The temperature of the drying treatment in the drying step is preferably at least 60° C. or higher, more preferably 80° C. or higher, even more preferably 120° C. or higher, and most preferably 140° C. or higher. When the polyphenylene ether is dried at a temperature of 60° C. or higher, the content of high-boiling-point volatile components in the polyphenylene ether powder can be efficiently reduced.

[0054] In order to obtain polyphenylene ether with high efficiency, a method of increasing the drying temperature, a method of increasing the degree of vacuum in the drying atmosphere, a method of stirring during drying, and the like are effective, but a method of increasing the drying temperature is particularly preferable from the viewpoint of production efficiency. In the drying step, it is preferable to use a dryer equipped with a mixing function. Examples of the mixing function include a stirring type dryer and a rolling type dryer. This allows the processing amount to be increased, and the productivity to be maintained at a high level.

[0055] The polyphenylene ether of this embodiment can also be produced by a redistribution reaction in which a polyphenylene ether derived from a phenol of formula (2) is equilibrated with a phenolic compound of formula (1) in the presence of an oxidizing agent. Redistribution reactions are known in the art and are described, for example, in U.S. Patent No. 3,496,236 to Cooper et al. and U.S. Patent No. 5,880,221 to Liska et al.

[0056] (Modification reaction process) There is no limitation on the method for introducing a functional group into a hydroxyl group of an unmodified polyphenylene ether. For example, the functional group can be obtained by a reaction of a hydroxyl group of an unmodified polyphenylene ether with a carboxylic acid having a carbon-carbon double bond (hereinafter, carboxylic acid) to form an ester bond. The ester bond can be formed by various known methods, such as a) a reaction between a carboxylic acid halide and a hydroxyl group at the polymer terminal, b) a reaction with a carboxylic acid anhydride to form an ester bond, c) a direct reaction with a carboxylic acid, and d) a method using an ester exchange reaction. The reaction of a with an carboxylic acid halide is one of the most common methods. Although chlorides and bromides are generally used as carboxylic acid halides, other halogens may also be used. The reaction may be either a direct reaction with a hydroxyl group or a reaction with an alkali metal salt of a hydroxyl group. In the direct reaction of a carboxylic acid halide with a hydroxyl group, an acid such as hydrogen halide is generated, so a weak base such as an amine may be used in order to trap the acid. In the reaction of b with a carboxylic acid anhydride or the direct reaction of c with a carboxylic acid, a compound such as a carbodiimide or dimethylaminopyridine may be coexisted in order to activate the reaction site and promote the reaction. In the case of the transesterification reaction of d, it is desirable to remove the generated alcohols as necessary. In addition, known metal catalysts may be used to promote the reaction. After the reaction, the reaction mixture may be washed with water, an acidic or alkaline aqueous solution to remove by-products such as amine salts, or the polymer solution may be dropped into a poor solvent such as alcohols to recover the target product by reprecipitation. After washing the polymer solution, the solvent may be distilled off under reduced pressure to recover the polymer.

[0057] The method for producing the modified polyphenylene ether of the present embodiment is not limited to the method for producing the polyfunctional modified polyphenylene ether of the present embodiment described above, and the order and number of the above-mentioned oxidative polymerization step, copper extraction and by-product removal step, liquid-liquid separation step, and concentration and drying step may be appropriately adjusted.

[0058] For example, the polyphenylene ether of the present embodiment may be obtained by oxidatively polymerizing 3-pentadecylphenol or commercially available cardanol as the phenol of formula (1), and optionally 2,6-dimethylphenol as the phenol of formula (2), and then introducing at least one partial structure selected from the group consisting of formulas (8), (9), (10), and (11) into the obtained polyphenylene ether. The polyphenylene ether of the present embodiment may be obtained by introducing at least one partial structure selected from the group consisting of modified 3-pentadecylphenol or modified cardanol as the phenol of formula (1). The polyphenylene ether of the present embodiment may be obtained by oxidative polymerization of modified 3-pentadecylphenol or modified cardanol as the phenol of formula (1) and, optionally, 2,6-dimethylphenol as the phenol of formula (2), and further, the polyphenylene ether of the present embodiment may be obtained by oxidative polymerization of modified 3-pentadecylphenol or modified cardanol as the phenol of formula (1) and, optionally, 2,6-dimethylphenol as the phenol of formula (2), and then introducing at least one partial structure selected from the group consisting of formulas (8), (9), (10), and (11) into the obtained polyphenylene ether.

[0059] <Thermosetting composition> The polyphenylene ether of the present embodiment can be used as a raw material for a thermosetting composition. The thermosetting composition of the present embodiment is not particularly limited as long as it contains the polyphenylene ether of the present embodiment, but it is preferable that the thermosetting composition further contains a crosslinking agent and an organic peroxide, and if desired, can further contain a thermoplastic resin (including polyphenylene ethers other than the polyphenylene ether of the present embodiment), a flame retardant, a silica filler, a solvent, etc.

[0060] The content of the polyphenylene ether of this embodiment in the thermosetting composition of this embodiment is preferably from 0.5 to 95 mass %, more preferably from 20 to 93 mass %, and even more preferably from 40 to 90 mass %.

[0061] The components of the thermosetting composition of this embodiment are described below.

[0062] (Crosslinking agent) Any crosslinking agent capable of initiating or facilitating a crosslinking reaction can be used in the thermosetting composition of the present embodiments. The crosslinking agent preferably has a number average molecular weight of not more than 4000. When the number average molecular weight of the crosslinking agent is not more than 4000, an increase in the viscosity of the thermosetting composition can be suppressed, and good resin fluidity can be obtained during heat molding. The number average molecular weight may be a value measured by a general molecular weight measurement method, specifically, a value measured by GPC, etc.

[0063] From the viewpoint of the crosslinking reaction, the crosslinking agent preferably has an average of two or more carbon-carbon unsaturated double bonds per molecule. The crosslinking agent may be composed of one type of compound or two or more types of compounds. In addition, the term "carbon-carbon unsaturated double bond" as used herein refers to a double bond located at an end branched from the main chain when the crosslinking agent is a polymer or oligomer. An example of the carbon-carbon unsaturated double bond is a 1,2-vinyl bond in polybutadiene.

[0064] When the number average molecular weight of the crosslinking agent is less than 600, the number (average value) of carbon-carbon unsaturated double bonds per molecule of the crosslinking agent is preferably 2 to 4. When the number average molecular weight of the crosslinking agent is 600 or more and less than 1,500, the number (average value) of carbon-carbon unsaturated double bonds per molecule of the crosslinking agent is preferably 4 to 26. When the number average molecular weight of the crosslinking agent is 1,500 or more and less than 4,000, the number (average value) of carbon-carbon unsaturated double bonds per molecule of the crosslinking agent is preferably 26 to 60. When the number average molecular weight of the crosslinking agent is within the above range, the number of carbon-carbon unsaturated double bonds is equal to or more than the specific value, so that the thermosetting composition of this embodiment has a higher reactivity of the crosslinking agent and a higher crosslink density of the cured product of the thermosetting composition, and as a result, it can provide better heat resistance. On the other hand, when the number average molecular weight of the crosslinking agent is within the above range, the number of carbon-carbon unsaturated double bonds is equal to or less than the specific value, so that it can provide better resin fluidity during hot molding.

[0065] Examples of the crosslinking agent include trialkenyl isocyanurate compounds such as triallyl isocyanurate (TAIC), trialkenyl cyanurate compounds such as triallyl cyanurate (TAC), polyfunctional methacrylate compounds having two or more methacrylic groups in the molecule, polyfunctional acrylate compounds having two or more acrylic groups in the molecule, polyfunctional vinyl compounds having two or more vinyl groups in the molecule such as polybutadiene, vinylbenzyl compounds such as divinylbenzene having a vinylbenzyl group in the molecule, and polyfunctional maleimide compounds having two or more maleimide groups in the molecule such as 4,4'-bismaleimide diphenylmethane. These crosslinking agents are used alone or in combination of two or more. Among these, the crosslinking agent preferably contains at least one compound selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, and polybutadiene. When the crosslinking agent contains at least one or more of the compounds described above, the thermosetting composition has better compatibility between the crosslinking agent and the polyphenylene ether, and better coatability, and when mounted on an electronic circuit board, the board properties tend to be better.

[0066] The mass ratio of the polyphenylene ether of this embodiment to the crosslinking agent (polyphenylene ether of this embodiment:crosslinking agent) is preferably 25:75 to 95:5, and more preferably 32:68 to 85:15, from the viewpoints of improving the compatibility between the crosslinking agent and the polyphenylene ether, the coatability of the thermosetting composition, and achieving even better properties of the mounted electronic circuit board.

[0067] (organic peroxide) In this embodiment, any organic peroxide capable of promoting the polymerization reaction of the thermosetting composition comprising the polyphenylene ether and a crosslinking agent of this embodiment can be used. Examples of organic peroxides include benzoyl peroxide, cumene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, di-t-butyl peroxide, t-butylcumyl peroxide, di(2-t-butylperoxyisopropyl)benzene, 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, dicumyl peroxide, di-t-butylperoxyisophthalate, t-butylperoxybenzoate, 2,2-bis(t-butylperoxy)butane, 2,2-bis(t-butylperoxy)octane, 2,5-dimethyl-2,5-di(benzoylperoxy)hexane, di(trimethylsilyl)peroxide, and trimethylsilyltriphenylsilyl peroxide. Radical generators such as 2,3-dimethyl-2,3-diphenylbutane can also be used as reaction initiators for thermosetting compositions. Among them, 2,5-dimethyl-2,5-di(t-butylperoxy)hexyne-3, di(2-t-butylperoxyisopropyl)benzene, and 2,5-dimethyl-2,5-di(t-butylperoxy)hexane are preferred from the viewpoint of providing a cured product having excellent heat resistance and mechanical properties and a low dielectric tangent (and preferably a low dielectric constant).

[0068] The one-minute half-life temperature of the organic peroxide is preferably 155 to 185° C., more preferably 160 to 180° C., and even more preferably 165 to 175° C. When the one-minute half-life temperature of the organic peroxide is within the range of 155 to 185° C., the compatibility of the organic peroxide with the modified PPE, the coatability of the thermosetting composition, and the properties of the mounted electronic circuit board tend to be further improved. In this specification, the one-minute half-life temperature is the temperature at which the organic peroxide decomposes and the amount of active oxygen is reduced to half in one minute. The one-minute half-life temperature is a value confirmed by a method in which an organic peroxide is dissolved in a solvent inactive against radicals, such as benzene, to a concentration of 0.05 to 0.1 mol / L, and the organic peroxide solution is thermally decomposed in a nitrogen atmosphere.

[0069] Examples of organic peroxides having a one-minute half-life temperature in the range of 155 to 185°C include t-hexylperoxyisopropyl monocarbonate (155.0°C), t-butylperoxy-3,5,5-trimethylhexanoate (166.0°C), t-butylperoxylaurate (159.4°C), t-butylperoxyisopropyl monocarbonate (158.8°C), t-butylperoxy2-ethylhexyl monocarbonate (161.4°C), t-hexylperoxybenzoate (160.3°C), 2,5-dimethyl-2,5-di(benzoylperoxy)hexane (158.2°C), and the like. ), t-butyl peroxyacetate (159.9°C), 2,2-di-(t-butylperoxy)butane (159.9°C), t-butyl peroxybenzoate (166.8°C), n-butyl 4,4-di-(t-butylperoxy)valerate (172.5°C), di(2-t-butylperoxyisopropyl)benzene (175.4°C), dicumyl peroxide (175.2°C), di-t-hexyl peroxide (176.7°C), 2,5-dimethyl-2,5-di(t-butylperoxy)hexane (179.8°C), and t-butylcumyl peroxide (173.3°C).

[0070] The content of the organic peroxide, based on 100 parts by mass in total of the polyphenylene ether and the crosslinking agent of this embodiment, is preferably 0.05 parts by mass or more, more preferably 0.5 parts by mass or more, even more preferably 1 part by mass or more, and still more preferably 1.5 parts by mass or more, from the viewpoint of achieving even better compatibility between the organic peroxide and the modified PPE and even better coatability of the thermosetting composition; and is preferably 5 parts by mass or less, more preferably 4.5 parts by mass or less, from the viewpoint of achieving excellent board properties when the thermosetting composition is mounted on an electronic circuit board.

[0071] (thermoplastic resin) The thermoplastic resin is preferably at least one selected from the group consisting of a block copolymer of a vinyl aromatic compound and an olefin-based alkene compound and a hydrogenated product thereof (a hydrogenated block copolymer obtained by hydrogenating a block copolymer of a vinyl aromatic compound and an olefin-based alkene compound), and a homopolymer of a vinyl aromatic compound. From the viewpoints of achieving better compatibility with the polyphenylene ether of the present embodiment, resin fluidity, coatability of the thermosetting composition, and heat resistance during curing, the weight average molecular weight of the thermoplastic resin is preferably more than 50,000 and not more than 780,000, more preferably 60,000 to 750,000, and even more preferably 70,000 to 700,000. When the thermosetting composition contains the polyphenylene ether of this embodiment, a crosslinking agent, and an organic peroxide, and a thermoplastic resin having the type and weight-average molecular weight described above, the compatibility of the polyphenylene ether of this embodiment with the other components and the coatability onto substrates and the like tend to be good, and thus the substrate properties when incorporated into an electronic circuit board may also be excellent. The weight average molecular weight can be determined by the method described in the Examples below.

[0072] The content of the vinyl aromatic compound-derived unit in the block copolymer or its hydrogenated product is preferably 20% by mass or more, more preferably 22% by mass or more, 24% by mass or more, 26% by mass or more, 28% by mass or more, 30% by mass or more, or 32% by mass or more. The upper limit is preferably 70% by mass or less, more preferably 69% by mass or less, 68% by mass or less, or 67% by mass or less. By having the content of the vinyl aromatic compound-derived unit in the block copolymer or its hydrogenated product be 20 to 70% by mass, the compatibility with the polyphenylene ether of the present embodiment is further improved, and / or the adhesive strength with the metal foil tends to be further improved.

[0073] The vinyl aromatic compound may be any compound having an aromatic ring and a vinyl group in the molecule, and examples thereof include styrene. The olefin-based alkene compound may be any alkene having a linear or branched structure in the molecule, and examples thereof include ethylene, propylene, butylene, isobutylene, butadiene, and isoprene.

[0074] Specifically, from the viewpoint of having even better compatibility with polyphenylene ether, the thermoplastic resin is preferably at least one selected from the group consisting of styrene-butadiene block copolymers, styrene-ethylene-butadiene block copolymers, styrene-ethylene-butylene block copolymers, styrene-butadiene-butylene block copolymers, styrene-isoprene block copolymers, styrene-ethylene-propylene block copolymers, styrene-isobutylene block copolymers, hydrogenated styrene-butadiene block copolymers, hydrogenated styrene-ethylene-butadiene block copolymers, hydrogenated styrene-butadiene-butylene block copolymers, hydrogenated styrene-isoprene block copolymers, and homopolymers of styrene (polystyrene), and more preferably at least one selected from the group consisting of styrene-butadiene block copolymers, hydrogenated styrene-butadiene block copolymers, and polystyrene.

[0075] The hydrogenation rate in the hydrogenated product is not particularly limited, and some of the carbon-carbon unsaturated double bonds derived from the olefin-based alkene compound may remain.

[0076] The content of the thermoplastic resin is preferably 2 to 20 parts by mass, more preferably 3 to 19 parts by mass, further preferably 4 to 18 parts by mass, and particularly preferably 5 to 17 parts by mass, based on 100 parts by mass of the total of the polyphenylene ether of this embodiment and the crosslinking agent. When the content is within the above numerical range, the thermosetting composition of this embodiment has better compatibility between the thermoplastic resin and the polyphenylene ether of this embodiment and better coatability, and tends to have better board properties when mounted on an electronic circuit board.

[0077] The thermosetting composition of the present embodiment may also contain a thermoplastic resin other than the thermoplastic resin having the type and weight average molecular weight described above.

[0078] (Flame retardant) The thermosetting composition of the present embodiment preferably contains a flame retardant. The flame retardant is not particularly limited as long as it is incompatible with other components contained in the thermosetting composition after the thermosetting composition is cured, from the viewpoint of improving heat resistance. Preferably, the flame retardant is incompatible with the polyphenylene ether of the present embodiment and / or the crosslinking agent in the thermosetting composition after the thermosetting composition is cured. Examples of the flame retardant include inorganic flame retardants such as antimony trioxide, aluminum hydroxide, magnesium hydroxide, and zinc borate; aromatic bromine compounds such as hexabromobenzene, decabromodiphenylethane, 4,4-dibromobiphenyl, and ethylene bistetrabromophthalimide; and phosphorus-based flame retardants such as resorcinol bis-diphenyl phosphate and resorcinol bis-dixylenyl phosphate. These flame retardants may be used alone or in combination of two or more. Among these, the flame retardant is preferably decabromodiphenylethane from the viewpoints of compatibility between the flame retardant and the modified PPE, coatability of the thermosetting composition, and superior properties of the mounted electronic circuit board.

[0079] The content of the flame retardant is not particularly limited, but from the viewpoint of maintaining flame retardancy at the V-0 level of UL Standard 94, it is preferably 5 parts by mass or more, more preferably 10 parts by mass or more, and even more preferably 15 parts by mass or more, relative to 100 parts by mass of the total of the polyphenylene ether resin of the present embodiment and the crosslinking agent. Moreover, from the viewpoint of maintaining a low dielectric tangent of the obtained cured product (preferably also maintaining a low dielectric constant), the content of the flame retardant is preferably 50 parts by mass or less, more preferably 45 parts by mass or less, and even more preferably 40 parts by mass or less.

[0080] (Silica filler) The thermosetting composition of the present embodiment may contain a silica filler. Examples of the silica filler include natural silica, fused silica, synthetic silica, amorphous silica, aerosil, and hollow silica. The content of the silica filler may be 10 to 100 parts by mass relative to 100 parts by mass of the total of the polyphenylene ether resin and the crosslinking agent of the present embodiment. The silica filler may be surface-treated with a silane coupling agent or the like.

[0081] (solvent) From the viewpoint of solubility, the solvent is preferably an aromatic compound such as toluene or xylene, methyl ethyl ketone (MEK), cyclopentanone, cyclohexanone, chloroform, etc. These solvents may be used alone or in combination of two or more. When the thermosetting composition of the present embodiment contains a solvent, it can be in the form of a varnish in which the solid components in the thermosetting composition are dissolved or dispersed in the solvent, and a resin film can be formed from the thermosetting composition of the present embodiment.

[0082] <Prepreg> The prepreg of the present embodiment includes a substrate and the thermosetting composition of the present embodiment described above, and is preferably a composite including the substrate and the thermosetting composition of the present embodiment impregnated or applied to the substrate. The prepreg can be obtained, for example, by impregnating a substrate such as a glass cloth with the thermosetting composition in the form of a varnish, and then drying and removing the solvent with a hot air dryer or the like.

[0083] Examples of the substrate include various glass cloths such as roving cloth, cloth, chopped mat, and surfacing mat; asbestos cloth, metal fiber cloth, and other synthetic or natural inorganic fiber cloths; woven or nonwoven fabrics obtained from liquid crystal fibers such as fully aromatic polyamide fibers, fully aromatic polyester fibers, and polybenzoxazole fibers; natural fiber cloths such as cotton cloth, linen cloth, and felt; natural cellulose-based substrates such as carbon fiber cloth, craft paper, cotton paper, and cloth obtained from paper-glass mixed fiber yarn; and polytetrafluoroethylene porous films. Among these, glass cloth is preferable. These substrates may be used alone or in combination of two or more.

[0084] The proportion of the solid content of the thermosetting composition of this embodiment in the prepreg (components other than the solvent of the thermosetting composition) is preferably 30 to 80 mass %, more preferably 40 to 70 mass %. When the proportion is 30 mass % or more, the insulation reliability tends to be more excellent when the prepreg is used for electronic boards, etc. When the proportion is 80 mass % or less, the mechanical properties such as flexural modulus tend to be more excellent in applications such as electronic boards.

[0085] <Laminate> The laminate of the present embodiment is preferably a metal-clad laminate obtained by laminating the thermosetting composition of the present embodiment or the prepreg of the present embodiment and the metal foil, and curing the thermosetting composition or the prepreg. The metal-clad laminate preferably has a configuration in which the cured product of the prepreg (hereinafter also referred to as a "cured product composite") and the metal foil are laminated and adhered to each other, and the metal-clad laminate of this configuration is suitably used as a material for electronic substrates. Examples of the metal foil include aluminum foil and copper foil. Among these, copper foil is preferred because of its low electrical resistance. The cured composite to be combined with the metal foil may be one sheet or multiple sheets, and depending on the application, the cured composite may be processed into a metal-clad laminate by laminating a metal foil on one or both sides of the cured composite.

[0086] Examples of methods for producing a metal-clad laminate include a method in which a composite (e.g., the above-mentioned prepreg) is formed from a thermosetting composition and a substrate, this is layered with metal foil, and the thermosetting composition is cured to obtain a laminate in which the cured laminate and the metal foil are laminated together.

[0087] At least a part of the metal foil can be removed from the metal-clad laminate to form a printed wiring board. The printed wiring board can typically be formed by a method of pressurizing and hot molding using the prepreg of the present embodiment described above. Examples of the substrate include the same as those described above for the prepreg. The printed wiring board contains the thermosetting composition of the present embodiment, and thus has excellent heat resistance and electrical properties (low dielectric tangent and / or low dielectric constant), can suppress fluctuations in electrical properties due to environmental changes, and has excellent insulation reliability and mechanical properties. EXAMPLES

[0088] The present embodiment will be described in more detail below based on examples, but the present embodiment is not limited to the following examples.

[0089] First, the measurement methods and evaluation criteria for each physical property will be described below.

[0090] (1) Reduced viscosity (ηsp / c) A 0.5 g / dL chloroform solution of polyphenylene ether was prepared, and the reduced viscosity (ηsp / c) (dL / g) at 30° C. was determined using an Ubbelohde viscosity tube.

[0091] (2) The molar ratio of the repeating units derived from phenol of formula (1) and the repeating units derived from phenol of formula (2) to the total of 100 mol % of the repeating units derived from phenol of formula (1) and the repeating units derived from phenol of formula (2) (2-1) 0.0245 g of 1,3,5-trimethoxybenzene (molecular weight: 168) was precisely weighed as an internal standard and dissolved in deuterated chloroform to prepare a deuterated chloroform solution containing 0.5% by mass of the internal standard. (2-2) 0.0575 g of the polyphenylene ether obtained in the examples and comparative examples was precisely weighed and dissolved in deuterated chloroform containing 0.5% by mass of an internal standard to prepare a polyphenylene ether solution with a concentration of 5% by mass. (2-3) Polyphenylene ether solution with a concentration of 5% by mass 1 H-NMR measurement (JEOL 500 MHz, 512 accumulations, measurement temperature: room temperature) was performed, and the measurement data was analyzed by the following procedure using chloroform (7.25 ppm) as the chemical shift standard.

[0092] The signals derived from the repeating unit derived from phenol of formula (1) and the repeating unit derived from phenol of formula (2) were identified, and their respective contents were calculated. For example, in the polyphenylene ethers obtained in Examples 1 to 7, the signal derived from the repeating unit derived from phenol of formula (1), i.e., the 2-tert-butyl-cardanol structure, and the signal derived from the repeating unit derived from phenol of formula (2), i.e., the 2,6-dimethylphenol structure, were assigned as follows. The peaks of the repeating units derived from phenol of formula (1) and the repeating units derived from phenol of formula (2) appear in the following regions. Peaks derived from hydrogen atoms of the methyl groups contained in the 2-tert-butyl-cardanol unit (3H): 0.80 to 0.96 ppm Peaks (2H) derived from hydrogen atoms of the methylidene group (=CH2) contained in the 2-tert-butyl-cardanol unit: 4.90 to 5.10 ppm Peaks derived from hydrogen atoms in the aromatic ring of the 2,6-dimethylphenylene unit (2H): 6.39 to 6.62 ppm

[0093] The integral value of the above signal can be examined, and the number of moles of the repeating unit derived from phenol of formula (1) based on the weight of the polyphenylene ether can be calculated using the following formulas (I) to (III). C = {A × B / 100} / 168... Formula (I) F = {((Da / 3) + (Db / 2)) / (E / 9)} × C Formula (II) H=F / G×10 6 Formula (III) In the formula, the meanings of each symbol are as follows. A: Amount of deuterated chloroform used in the measurement (g) B: Concentration of the internal standard in the deuterated chloroform solution (mass%) C: The number of moles (mol) of 1,3,5-trimethoxybenzene contained in the deuterated chloroform solution of polyphenylene ether used in the measurement Da: integral value of the peak derived from the hydrogen atom of the methyl group contained in the 2-tert-butyl-cardanol unit Db: Integration value of the peak (2H) due to the hydrogen atom of the methylidene group (=CH2) contained in the 2-tert-butyl-cardanol unit E: Integral value of the peaks derived from the hydrogen atoms of the methyl group of 1,3,5-trimethoxybenzene F: The number of moles (mol) of repeating units derived from 2-tert-butyl-cardanol units contained in the deuterated chloroform solution of polyphenylene ether used in the measurement G: Amount of polyphenylene ether used in the measurement (g) H: The number of moles of repeating units derived from 2-tert-butyl-cardanol units based on the weight of polyphenylene ether (μmol / g)

[0094] The integral value of the above signal is examined, and the number of moles of the repeating unit derived from phenol of formula (2) based on the weight of the polyphenylene ether can be calculated using the following formulas (IV) to (VI). C = {A × B / 100} / 168... Formula (IV) J = {(I / 2} / (E / 9)} × C... Formula (V) K=J / G×10 6 Formula (VI) In the formula, the meanings of each symbol are as follows. I: Integral value of peaks originating from hydrogen atoms of aromatic ring of 2,6-dimethylphenylene unit J: The number of moles (mol) of 2,6-dimethylphenylene units contained in the deuterated chloroform solution of polyphenylene ether used in the measurement K: The number of moles of 2,6-dimethylphenylene units based on the weight of polyphenylene ether (μmol / g)

[0095] Using formula (VII) and formula (VIII), the ratio (%) of the repeating units derived from phenol of formula (1) and the repeating units derived from phenol of formula (2) to the total of 100 mol % of the repeating units derived from phenol of formula (1) and the repeating units derived from phenol of formula (2) was calculated. Percentage of repeating units derived from phenol of formula (1) ={H / (H+K)}×100 Formula (VII) Percentage of repeating units derived from phenol of formula (2) ={K / (H+K)}×100 Formula (VIII)

[0096] (3) Long-term solubility in methyl ethyl ketone (MEK solubility) 1.5 g of polyphenylene ether and 8.5 g of methyl ethyl ketone were weighed into a transparent glass screw tube. They were mixed at 20°C using a stirrer and a magnetic stirrer. After one day (24 hours), if the solution maintained its transparency, it was judged as "Good" (O); if it was clearly not dissolved or there was a large amount of insoluble matter, it was judged as "Poor" (X); and if there was some residual dissolution (some turbidity), it was judged as "△".

[0097] (4) Long-term solubility in toluene (TL solubility) 2 g of polyphenylene ether and 8 g of toluene were weighed into a transparent glass screw tube. They were mixed at 20°C using a stirrer and a magnetic stirrer. After one day (24 hours), if the solution maintained its transparency, it was judged as "Good" (O); if it was clearly not dissolved or if there was a large amount of insoluble matter, it was judged as "Poor" (X); and if there was some residual dissolution (some turbidity), it was judged as "△".

[0098] (5) Dielectric tangent of the cured product of the thermosetting composition The dielectric loss tangent at 10 GHz of the laminates manufactured in the examples and comparative examples was measured by a cavity resonance method. As a measuring device, a network analyzer (N5230A, manufactured by Agilent Technologies) and a cavity resonator (Cavity Resornator CP series) manufactured by Kanto Electronics Application Development Co., Ltd. were used. The laminates were cut into strips with a width of about 2 mm, a length of 50 mm, and a thickness of about 0.5 mm so that the warp of the glass cloth was the long side. Next, the laminates were placed in an oven at 105°C ± 2°C and dried for 2 hours, and then left to stand for 24 ± 5 ​​hours in an environment of 23°C and relative humidity of 50 ± 5%. Thereafter, the dielectric loss tangent was measured at a frequency of 10 GHz using the above measuring device in an environment of 23°C and relative humidity of 50 ± 5%.

[0099] The methods for producing polyphenylene ether in each of the Examples and Comparative Examples will be described below.

[0100] (Production Example 1) Cardanol (trade name LB-7250, manufactured by Tohoku Kako Co., Ltd., 50.0 g), p-toluenesulfonic acid monohydrate (0.851 g), and toluene (50 mL) were added in sequence to a 300 mL four-neck flask connected to a -10 ° C Dewar condenser, and stirred with a stirring blade. Then, the external temperature was set to 65 ° C with an aluminum block heating device and heated. Isobutene (21.6 g) was introduced over 2 hours and 30 minutes. After the introduction of isobutene, the mixture was stirred at an internal temperature of 60 ° C for 2 hours. After the external temperature was raised to 110 ° C, 27% aqueous sodium hydroxide solution (0.73 g) was dropped into the reaction solution. Ion-exchanged water (50 mL) was further added, stirred for 15 minutes, and then allowed to stand. Since the organic layer was suspended, ethyl acetate (300 mL) was added to completely dissolve it, and the organic layer was recovered using a separatory funnel and washed with saturated saline (200 mL). The resulting organic layer was dried over magnesium sulfate and concentrated using a rotary evaporator to obtain a brown oily crude product (60.1 g). The resulting crude product was purified by silica gel column chromatography (column diameter: 100 mm, column height: 16 cm, silica gel: 600 g, developing solvent: heptane / ethyl acetate = 15 / 1). The resulting fraction was concentrated using a rotary evaporator to obtain a pale yellow oily modified cardanol (46.7 g). The structure of the obtained compound was identified as follows: 1 This was done using H-NMR, and it was found that the main component was cardanol with a tert-butyl group introduced at the 2-position of the raw cardanol before the reaction.

[0101] Cardanol Source: 1 H-NMR(CDCl3) δ 7.15-7.10(m,1H),6.78-6.73(m,1H),6.68-6.62(m,2H),5.88-5.77(m,0.37H),5.50-5.29(m,3.44H),5.10-4.95(m,0.80H),4.81-4.64( m,1H),2.88-2.75(m,2.14H),2.55(t,2.13H),2.08-1.98(m,3.31H),1.69-1.53(m,3.15H),1.51-1.12(m,14.10H),0.94-0.85(m,1.95H)

[0102] Modified cardanol (product): 1 H-NMR (CDCl3) δ 7.16 (d, 1H), 6.69 (dd, 1H), 6.49 (d, 1H), 5.88 - 5.77 (m, 0.39H), 5.50 - 5.29 (m, 3.56H), 5.10 - 4.95 (m, 0.80H), 4.64 (s, 1H), 2.87 - 2.75 (m, 2.12H), 2.56 - 2.46 (m, 2.22H), 2.12 - 1.95 (m, 3.60), 1.65 - 1.53 (m, 2.62H), 1.43 - 1.24 (m, 23.42H), 0.96 - 0.80 (m, 2.20H)

[0103] (Example 1) A 1.0-liter jacketed reactor equipped with a sparger for introducing an oxygen-containing gas at the bottom of the reactor, stirring turbine blades and baffles, and a reflux condenser on the vent gas line at the top of the reactor was charged with a mixture of 0.12 g of cuprous oxide and 0.91 g of 47% hydrogen bromide, 0.29 g of N,N'-di-t-butylethylenediamine, 4.31 g of dimethyl-n-butylamine, 1.42 g of di-n-butylamine, phenol raw material (77.7 g of 2,6-dimethylphenol, 2.29 g of modified cardanol produced in Production Example 1), and 713 g of toluene. Next, air was introduced into the reactor from the sparger at a rate of 0.84 L / min while vigorously stirring, and oxygen was introduced at the same time. The polymerization temperature was adjusted by passing a heat medium through the jacket to maintain it at 40°C. 120 minutes after the start of air introduction, the aeration was stopped, the inside of the reactor was replaced with nitrogen gas, and 1.30 g of ethylenediaminetetraacetic acid tetrasodium salt tetrahydrate (a reagent manufactured by Dojindo Laboratories) was added as an aqueous solution of 200 g of water. The mixture was heated to 70°C, and copper extraction was carried out at 70°C for 4 hours. Thereafter, the mixture was separated into a polyphenylene ether solution (organic phase) and an aqueous phase to which the catalyst metal had been transferred by static separation. The above solution was mixed with methanol in a ratio of 10 to the polymer solution, and the polymer was precipitated. Wet polyphenylene ether was obtained by filtration under reduced pressure using a glass filter. Furthermore, the wet polyphenylene ether was washed with an amount of methanol in a ratio of 2.5 to the wet polyphenylene ether. The above washing operation was carried out three times. Next, the wet polyphenylene ether was kept at 100°C and 1 mmHg for 4 hours, and dry polyphenylene ether was obtained. The obtained polyphenylene ether was subjected to the respective measurements by the above-mentioned methods, and it was confirmed that the modified cardanol was copolymerized. The analytical results are shown in Table 1.

[0104] Example 2 The same operation as in Example 1 was carried out except that the phenol raw material was 60.4 g of 2,6-dimethylphenol and 19.6 g of modified cardanol. The analytical results are shown in Table 1.

[0105] Example 3 The same operation as in Example 1 was carried out except that the phenol raw material was 46.2 g of 2,6-dimethylphenol and 33.8 g of modified cardanol. The analytical results are shown in Table 1.

[0106] Example 4 The same operation as in Example 1 was carried out except that the phenol raw material was 6.3 g of 2,6-dimethylphenol and 73.7 g of modified cardanol. The analytical results are shown in Table 1.

[0107] Example 5 The same operation as in Example 1 was carried out except that the phenol raw material was 2.9 g of 2,6-dimethylphenol and 77.1 g of modified cardanol. The analytical results are shown in Table 1.

[0108] Example 6 Oxidative polymerization, copper extraction, liquid-liquid separation and concentration by a rotary evaporator were carried out in the same manner as in Example 3, and a polymer solution with a polymer concentration of 25 mass % was used as a stock solution for the modification reaction (unmodified polyphenylene ether solution A). A 500mL three-neck flask equipped with a line for introducing nitrogen gas at the top of the reactor and a reflux condenser at the vent gas line at the top of the reactor was charged with 200g of unmodified polyphenylene ether solution A and 0.20g of 4-dimethylaminopyridine after replacing the inside of the reactor with nitrogen. 9.3mL of triethylamine was added using a syringe while stirring. Then, 3.2mL of methacryloyl chloride was collected in a syringe and dropped into the system at room temperature. After the dropwise addition was completed, the flask was heated in an oil bath and stirring was continued at 90°C for 1 hour. Then, the reaction was continued under reflux by heating in an oil bath. Heating was stopped 4 hours after the start of reflux, and after returning to room temperature, 8g of methanol was added to stop the reaction. Next, the reaction solution was filtered using a glass filter to obtain a solution from which the by-product triethylammonium salt had been removed. The above solution was mixed with methanol in a ratio of 10 to the polymer solution to perform precipitation of the polymer. Wet polyphenylene ether was obtained by vacuum filtration using a glass filter. The wet polyphenylene ether was further washed with methanol in an amount such that the ratio of methanol to wet polyphenylene ether was 2.5. The above washing operation was repeated three times. The wet polyphenylene ether was then kept at 100° C. and 1 mmHg for 8 hours to obtain a dry polyphenylene ether. 1 H-NMR measurement was performed and the proton peak (5.5 to 6.5 ppm) derived from the olefin of the methacryl group was confirmed, indicating that the hydroxyl group had been modified to a methacryl group. The analytical results are shown in Table 2.

[0109] Example 7 To 79 parts by mass of the polyphenylene ether described in Example 6, 20 parts by mass of TAIC (manufactured by Nippon Kasei Co., Ltd.) and 1 part by mass of organic peroxide (Perbutyl P, manufactured by NOF Corp.) were added to toluene, stirred and dissolved to obtain a varnish (solid content concentration 58% by mass). After impregnating L glass cloth (manufactured by Asahi Schwebel Co., Ltd., style: 2116) with this varnish, the excess varnish was scraped off by passing it through a specified slit, and the prepreg was obtained by drying for a specified time in a drying oven at 105°C and removing the toluene. This prepreg was cut to a specified size, and the solid content of the thermosetting composition in the prepreg was calculated by comparing the mass of the prepreg with the mass of a glass cloth of the same size, and was found to be 52% by mass. A predetermined number of these prepregs were stacked, and copper foil (GTS-MP foil, 35 μm thick, manufactured by Furukawa Electric Co., Ltd.) was placed on both sides of the stacked prepregs, and the resulting laminate was vacuum pressed to obtain a copper-clad laminate. In this vacuum pressing process, the laminate was first heated from room temperature at a temperature increase rate of 2°C / min while applying a pressure of 40 kg / cm. 2 After the temperature reached 200°C, the pressure was increased to 40 kg / cm while maintaining the temperature at 200°C. 2 and duration of 60 minutes were adopted. Next, the copper foil was removed from the copper-clad laminate by etching to obtain a laminate (thickness: about 0.5 mm). The analytical results are shown in Table 3.

[0110] Comparative Example 1 The same operation as in Example 1 was carried out, except that the phenol raw material was 80 g of 2,6-dimethylphenol, and the air supply was stopped 117 minutes after the start of air introduction. The analytical results are shown in Table 1.

[0111] Comparative Example 2 In a 4.1-liter jacketed reactor equipped with a sparger for introducing oxygen-containing gas at the bottom of the reactor, stirring turbine blades and baffles, and a reflux condenser on the vent gas line at the top of the reactor, 0.88 g of cupric chloride dihydrate, 3.76 g of 35% hydrochloric acid, 33.57 g of N,N,N',N'-tetramethylpropanediamine, 850 g of n-butanol, 1982 g of methanol, and 630 g of 2,6-dimethylphenol were placed. The composition weight ratio of the solvent used was n-butanol:methanol=30:70. Next, oxygen was introduced into the reactor from the sparger at a rate of 410 mL / min while vigorously stirring, and at the same time, the polymerization temperature was adjusted by passing a heat medium through the jacket to maintain it at 40°C. The polymerization liquid gradually took on the form of a slurry. 200 minutes after the start of oxygen introduction, the aeration of the oxygen-containing gas was stopped, and a 50% aqueous solution of 4.56 g of ethylenediaminetetraacetic acid tripotassium salt (a reagent manufactured by Dojindo Laboratories) was added to the polymerization mixture, followed by the addition of a 20% methanol solution of 8.52 g of hydroquinone (a reagent manufactured by Wako Pure Chemical Industries) little by little. The obtained polymerization liquid was transferred to a 4.1-liter jacketed reactor equipped with stirring turbine blades and baffles, and a reflux condenser on the vent gas line at the top of the reactor, and reacted at 60°C for 3 hours. After the reaction was completed, the mixture was filtered and washed three times with a washing liquid (b) in an amount such that the mass ratio (b / a) of the methanol washing liquid (b) to the polyphenylene ether (a) to be washed was 4, to obtain wet polyphenylene ether. The mixture was then vacuum-dried at 120°C for 4 hours to obtain dry polyphenylene ether. The analytical results of the obtained polyphenylene ether are shown in Table 1.

[0112] Comparative Example 3 A 1.5-liter jacketed reactor equipped with a sparger for introducing an oxygen-containing gas at the bottom of the reactor, stirring turbine blades and baffles, and a reflux condenser on the vent gas line at the top of the reactor was charged with a mixture of 0.092 g of cuprous oxide and 0.69 g of 47% hydrogen bromide, which had been previously prepared, 0.22 g of N,N'-di-t-butylethylenediamine, 3.27 g of dimethyl-n-butylamine, 1.07 g of di-n-butylamine, 714.65 g of toluene, 65.03 g of 2,6-dimethylphenol, and 14.97 g of 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane. Then, air was introduced into the reactor from the sparger at a rate of 0.84 L / min while vigorously stirring, and the polymerization temperature was adjusted by passing a heat medium through the jacket to maintain it at 20°C. 150 minutes after the start of air introduction, the air flow was stopped, and the inside of the reactor was replaced with nitrogen gas. Then, 0.99 g of tetrasodium ethylenediaminetetraacetate tetrahydrate (a reagent manufactured by Dojindo Laboratories) was added to the polymerization mixture as an aqueous solution of 160 g of water. The mixture was then heated to 70°C, and copper extraction was carried out at 70°C for 2 hours. After that, the mixture was separated by standing separation into an unmodified polyphenylene ether solution (organic phase) and an aqueous phase to which the catalyst metal had been transferred. The mixture was then concentrated using a rotary evaporator, and the polymer solution with a polymer concentration of 25% by mass was used as the stock solution for the modification reaction (unmodified polyphenylene ether solution B). A 500mL three-neck flask equipped with a line for introducing nitrogen gas at the top of the reactor and a reflux condenser at the vent gas line at the top of the reactor was charged with 200g of unmodified polyphenylene ether solution B and 0.76g of 4-dimethylaminopyridine after replacing the inside of the reactor with nitrogen. 34mL of triethylamine was added using a syringe while stirring. Then, 12mL of methacryloyl chloride was collected in a syringe and dropped into the system at room temperature. After the dropwise addition was completed, the flask was heated in an oil bath and stirring was continued at 90°C for 1 hour. Then, the reaction was continued under reflux by heating in an oil bath. Heating was stopped 4 hours after the start of reflux, and after returning to room temperature, 8g of methanol was added to stop the reaction. Next, the reaction solution was filtered using a glass filter to obtain a solution from which the by-product triethylammonium salt had been removed. The above solution was mixed with methanol in a ratio of 10 to the polymer solution, and the polymer was precipitated. Wet polyphenylene ether was obtained by vacuum filtration using a glass filter. The wet polyphenylene ether was further washed with methanol in an amount such that the ratio of methanol to wet polyphenylene ether was 2.5. The above washing operation was repeated three times. The wet polyphenylene ether was then kept at 100° C. and 1 mmHg for 8 hours to obtain a dry polyphenylene ether. 1 H-NMR measurement was performed to confirm the proton peak derived from the olefin of the methacryl group, and it was determined that the hydroxyl group had been modified into a methacryl group. The analytical results are shown in Table 2.

[0113] Comparative Example 4 A laminate was obtained in the same manner as in Example 7, except that the polyphenylene ether described in Comparative Example 3 was used as the raw material. The analysis results are shown in Table 3.

[0114] (Production Example 2) The catalyst Fe2O3-SiO2-CuO (metal molar ratio Fe:Si:Cu=200:5:1) used for the methylation reaction was synthesized according to the reference “Catalysis Communication 111 (2018)1000-1003.” Next, quartz wool (10 mm high) was laid in a glass tube (inner diameter 20 mm, length 200 mm), and the catalyst pellets (120 mm high) were laid on top of the quartz wool. Wool (10 mm high) was then laid on top of the pellets, followed by glass beads (30 mm high). The catalyst layer was heated to 300°C using a mantle heater while nitrogen gas was supplied from the top of the glass tube (100 mL / min). A collection flask cooled in an acetone / dry ice bath was placed at the bottom of the glass tube. A previously prepared solution of cardanol (product name LB-7250, manufactured by Tohoku Kako Co., Ltd.):methanol:water = 1:5:1.5 (molar ratio) was continuously fed from the top of the glass tube at 0.35 mL / min using a liquid feed pump. The mantle heater was adjusted so that the catalyst temperature was 300°C, and continuous feeding was continued for 2 hours. After 2 hours, 35 g of solution was recovered in a collection flask. After concentrating under reduced pressure using an evaporator, 21 g of crude product was obtained. Furthermore, column purification of the crude product was carried out (developing solvent: a mixed solvent of heptane / ethyl acetate = 14 / 1). The separated solution was concentrated and dried under reduced pressure using an evaporator. As a result, a modified cardanol in the form of a pale yellow oil was obtained. The structure of the obtained compound was identified as follows: 1 The results were analyzed by H-NMR. As a result, methyl groups were introduced to the 2- and 6-positions of the cardanol raw material before the reaction, and the signals derived from the double bond sites in the side chains had disappeared, indicating that the main component was cardanol in which the double bond sites in the side chains were also methylated.

[0115] Modified Cardanol (Product): 1 H-NMR(CDCl3)δ 6.90-6.80(d,1.00H),6.70-6.60(d,1.04H),5.50-5.29(m,1.89H),4.64(s,1.11H),2.60-2.40(m,2.39H),2. 30-2.10(m,7.85H),2.10-1.90(m,4.35H)1.70-1.51(m,3.85H),1.51-1.12(m,20.88H),0.96-0.80(m,3.50H)

[0116] Example 8 The same operation as in Example 1 was carried out except that the phenol raw material was 61.6 g of 2,6-dimethylphenol and 18.4 g of the modified cardanol produced in Production Example 2. The analytical results are shown in Table 1.

[0117] [Table 1]

[0118] [Table 2]

[0119] [Table 3]

[0120] As shown in Tables 1, 2, and 3, by comparing Examples 1, 2, and 8 with Comparative Example 1, polyphenylene ethers having various reduced viscosities with enhanced solubility in toluene could be obtained. By comparing Examples 3 to 5 with Comparative Examples 1 and 2, polyphenylene ethers having various reduced viscosities with enhanced solubility in methyl ethyl ketone could be obtained. By comparing Example 6 with Comparative Example 3, it was shown that polyphenylene ethers having long-term solubility equivalent to that of known polyphenylene ethers known to have excellent long-term solubility in general-purpose solvents could be obtained. In addition, by comparing Example 7 with Comparative Example 4, it was shown that the polyphenylene ether of the present invention is useful as a substrate material having excellent dielectric loss tangent. [Industrial Applicability]

[0121] The polyphenylene ether of the present invention has excellent solvent solubility and is therefore industrially valuable as an electronic material and a modifier.

Claims

1. The copolymer comprises a repeating unit derived from a phenol represented by the formula (1) and a repeating unit derived from a phenol represented by the following formula (2): A polyphenylene ether comprising 1 to 100 mol % of repeating units derived from a phenol represented by the formula (1) and 0 to 99 mol % of repeating units derived from a phenol represented by the formula (2), relative to 100 mol % in total of the repeating units derived from a phenol represented by the formula (1) and the repeating units derived from a phenol represented by the formula (2), The phenol of the formula (1) is one or more phenols selected from the group consisting of modified 3-pentadecylphenol obtained by introducing a linear saturated hydrocarbon group having 1 to 12 carbon atoms or a substituent represented by formula (3) into 3-pentadecylphenol, and modified cardanol obtained by introducing a linear saturated hydrocarbon group having 1 to 12 carbon atoms or a substituent represented by formula (3) into cardanol, A polyphenylene ether, in which a total molar ratio of the repeating units derived from phenol of the formula (1) and the repeating units derived from phenol of the formula (2) is 80 mol % or more relative to 100 mol % of the polyphenylene ether. 【Chemistry 1】 ...Formula (1) (In formula (1), R １３ represents an optionally substituted saturated or unsaturated hydrocarbon group having 15 carbon atoms; R １１ and R １２ are each independently a hydrogen atom, a linear saturated hydrocarbon group having 1 to 12 carbon atoms, or a substituent represented by the following formula (3), １１ and R １２ Both are not hydrogen atoms at the same time.) 【Chemistry 2】 ...Formula (3) (In formula (3), R ３１ are each independently a linear alkyl group having 1 to 8 carbon atoms which may be substituted, or two R ３１ The atoms contained therein are bonded to each other to form a cyclic alkyl group having 1 to 8 carbon atoms, and R ３２ each independently represents an optionally substituted alkylene group having 1 to 8 carbon atoms; each b independently represents 0 or 1; R ３３ is a hydrogen atom, an optionally substituted alkyl group having 1 to 8 carbon atoms, or an optionally substituted phenyl group. 【Chemistry 3】 ...Formula (2) (In formula (2), R ２１ each independently represents an optionally substituted saturated hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom; R ２２ are each independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom.

2. 2. The polyphenylene ether according to claim 1, comprising 20 to 100 mol % of repeating units derived from phenol of formula (1) and 0 to 80 mol % of repeating units derived from phenol of formula (2), relative to 100 mol % in total of the repeating units derived from phenol of formula (1) and the repeating units derived from phenol of formula (2).

3. 3. The polyphenylene ether according to claim 1, which has a reduced viscosity (ηsp / c) of 0.03 to 0.90 dL / g as measured at 30° C. in a chloroform solution having a concentration of 0.5 g / dL using an Ubbelohde viscometer.

4. The R １１ is a t-butyl group, and the R １２ The polyphenylene ether according to claim 1 or 2, wherein is a hydrogen atom.

5. The method for producing the polyphenylene ether according to claim 1 or 2, comprising a step of oxidatively polymerizing the phenol represented by the formula (1).

6. A thermosetting composition comprising the polyphenylene ether of claim 1 or 2.

7. A prepreg comprising a substrate and the thermosetting composition of claim 6.

8. The prepreg according to claim 7 , wherein the substrate is a glass cloth.

9. A laminate comprising the cured prepreg according to claim 7 and a metal foil.

10. A laminate comprising the cured prepreg according to claim 8 and a metal foil.

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