Polyphenylene ether, method for producing the same, thermosetting composition, prepreg, and laminate

Abstract

To provide a polyphenylene ether having superior dielectric properties and a method for producing the same, and a thermosetting composition, a prepreg, and a laminate each including the polyphenylene ether.SOLUTION: A polyphenylene ether includes a repeat unit derived from a phenol of formula (1), a repeat unit derived from a phenol of formula (2), and a repeat unit derived from a phenol of formula (4).SELECTED DRAWING: None

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 Art

[0002] Polyphenylene ether (hereinafter also referred to as "PPE") has excellent high-frequency characteristics, flame retardancy, and heat resistance, and thus is widely used as a material for products and parts in the fields of electric and electronic, automotive, food and packaging, and other various industrial material fields. In particular, in recent years, applications as an electronic material such as a substrate material and as a modifier in various applications by taking advantage of its dielectric properties and heat resistance have been promoted.

[0003] However, in general, high molecular weight polyphenylene ether having a repeating unit derived from monohydric phenol typified by 2,6-dimethylphenol does not have sufficient dielectric properties in a high frequency band to be compatible with millimeter wave radar for the fifth generation communication system (5G).

[0004] Patent Document 1 discloses a resin composition showing a low dielectric tangent in a high frequency band using a polyphenylene ether derivative substituted with an unsaturated aliphatic hydrocarbon group. Patent Document 2 discloses a resin composition in a high-speed electronic circuit substrate showing a low dielectric tangent using a polyfunctional modified polyphenylene ether resin.

Prior Art Documents

Patent Documents

[0006] As mentioned above, Patent Documents 1 and 2 disclose methods for producing polyphenylene ether and the like to improve the dielectric properties of resin compositions. However, simply introducing unsaturated aliphatic hydrocarbon groups into polyphenylene ether or changing it to a polyfunctional group is insufficient to meet the high performance requirements for dielectric properties at high frequencies applicable to millimeter-wave radar for fifth-generation communication systems (5G), and an even lower dielectric loss tangent is necessary.

[0007] This invention has been made in view of the above problems, and aims to provide a polyphenylene ether with excellent dielectric properties and a method for producing the same. Furthermore, the objective is to provide thermosetting compositions, prepregs, and laminates using the polyphenylene ether. [Means for solving the problem]

[0008] In other words, the present invention is as follows: [1] It has repeating units derived from phenol of formula (1) below, repeating units derived from phenol of formula (2) below, and repeating units derived from phenol of formula (4) below. death, A repeating unit derived from phenol of formula (1), a repeating unit derived from phenol of formula (2), and a repeating unit derived from phenol of formula (4) totaling 100 mol%, comprising 5 to 50 mol% of the repeating unit derived from phenol of formula (1), 25 to 75 mol% of the repeating unit derived from phenol of formula (2), and 5 to 60 mol% of the repeating unit derived from phenol of formula (4). A polyphenylene ether characterized by the following features. [ka] (In formula (1), R 11 Each of these is independently a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom, and R 12 Each of these is independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom. [ka] (In formula (2), R 22Each is independently a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom, and two Rs 22 are not both hydrogen atoms, and R 21 is a partial structure represented by the following formula (3).

Chemical formula

Chemical formula

[10] A laminate comprising a cured prepreg described in [8] and a metal foil. [Effects of the Invention]

[0009] According to the present invention, a polyphenylene ether with excellent dielectric properties and a method for producing the same can be provided. Furthermore, a thermosetting composition, a prepreg, and a laminate using the polyphenylene ether can be provided. [Modes for carrying out the invention]

[0010] The following describes in detail embodiments for carrying out the present invention (hereinafter referred to as "this embodiment"). This embodiment is an example for explaining the present invention, and the present invention is not limited to this embodiment. The present invention can be implemented by modifying it as appropriate within the scope of its gist.

[0011] In this 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 otherwise inconsistent. In this specification, A(numerical value) to B(numerical value) means A or greater and B or less. In this specification, substituents include, for example, saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, halogen atoms, and the like.

[0012] <Polyphenylene ether> The polyphenylene ether of this embodiment contains at least a repeating unit derived from the phenol of formula (1), a repeating unit derived from the phenol of formula (2), and a repeating unit derived from the phenol of formula (4), and may consist only of the repeating unit derived from the phenol of formula (1), a repeating unit derived from the phenol of formula (2), and a repeating unit derived from the phenol of formula (4). [ka] (In formula (1), R 11 Each of these is independently a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom, and R 12 Each of these is independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom. [ka] (In formula (2), R 22 Each of these is independently a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom, and two R 22 Both are not hydrogen atoms, R 21 This is a substructure represented by the following equation (3). [ka] (In formula (3), R 31 Each of these is independently a linear alkyl group having 1 to 8 carbon atoms, which may be substituted, or two R 31 It is a cyclic alkyl structure with 1 to 8 carbon atoms bonded together, R 32 Each is independently an alkylene group having 1 to 8 carbon atoms, which may be substituted, and each is independently 0 or 1, R 33 (This is a hydrogen atom, an optionally substituted C1-C8 alkyl group, or an optionally substituted phenyl group.) [ka] (In formula (4), R 41 The above R 21 It has a different structure and is a saturated hydrocarbon group having 1 to 6 carbon atoms, which may be substituted, an aryl group having 6 to 12 carbon atoms, or a halogen atom, R 42 Each of these is independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom.

[0013] In the above equation (1), R 11 Each of these is preferably independently 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 even more preferably a methyl group. In formula (1), the two R 11 It is preferable that both have the same structure. The above R 11 Substituents for saturated hydrocarbon groups having 1 to 6 carbon atoms and aryl groups having 6 to 12 carbon atoms include saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and halogen atoms.

[0014] In the above equation (1), R 12 Each of them is preferably independently a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, more preferably a hydrogen atom or a methyl group, and even more preferably a hydrogen atom. In formula (1), the two R 12 The structures may be the same or different, but it is preferable that they be the same. The above R 12 Substituents for the hydrocarbon group having 1 to 6 carbon atoms and the aryl group having 6 to 12 carbon atoms include saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and halogen atoms.

[0015] In equation (2) above, R 22 Each of these is preferably independently a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms, or an aryl group having 6 to 12 carbon atoms that may be substituted with an alkyl group having 1 to 6 carbon atoms; more preferably a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms that may be substituted with an alkyl group having 1 to 6 carbon atoms; and even more preferably a hydrogen atom or a methyl group. In formula (2), the two R 22 It is preferable that they are different, and more preferably that one is a hydrogen atom and the other is a hydrocarbon group having 1 to 6 carbon atoms (preferably a methyl group). The above R 22Substituents for saturated or unsaturated hydrocarbon groups having 1 to 20 carbon atoms and aryl groups having 6 to 12 carbon atoms include saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and halogen atoms.

[0016] The substructure represented by formula (3) above is preferably a group containing secondary and / or tertiary carbons, such as an isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, tert-amyl group, 2,2-dimethylpropyl group, cyclohexyl group, or a structure having a phenyl group at its terminal, more preferably a tert-butyl group or a cyclohexyl group, and even more preferably a tert-butyl group. Note that the above R 31 Substituents in a linear alkyl group having 1 to 8 carbon atoms, the above R 32 Substituents in the alkylene group having 1 to 8 carbon atoms, and the above R 33 Examples of substituents on the C1-C8 alkyl group and phenyl group include C1-C10 saturated or unsaturated hydrocarbon groups, C6-C10 aryl groups, and halogen atoms.

[0017] In the above equation (4), R 41 is R 21 Unlike the above, it is preferably a saturated hydrocarbon group having 1 to 6 carbon atoms that may be substituted, or an aryl group having 6 to 12 carbon atoms that may be substituted, more preferably a methyl group or a phenyl group, and even more preferably a methyl group. The above / R 41 is R 21 Unlike, 41 It is preferable that the following equation (3') is not satisfied. [ka] (In formula (3'), R 31 Each of these is independently a linear alkyl group having 1 to 8 carbon atoms, which may be substituted, or two R 31 It is a cyclic alkyl structure with 1 to 8 carbon atoms bonded together, R 32Each is independently an alkylene group having 1 to 8 carbon atoms, which may be substituted, and each is independently 0 or 1, R 33 (This is a hydrogen atom, an optionally substituted C1-C8 alkyl group, or an optionally substituted phenyl group.) The above R 41 Substituents for saturated hydrocarbon groups having 1 to 6 carbon atoms and aryl groups having 6 to 12 carbon atoms include saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and halogen atoms.

[0018] In the above equation (4), R 42 Each of these is preferably independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom, more preferably a hydrogen atom, a methyl group, or a phenyl group, and even more preferably a hydrogen atom or a methyl group. In formula (4), the two R 42 Both may be hydrogen atoms, or one may be a hydrogen atom and the other a hydrocarbon group having 1 to 6 carbon atoms (preferably a methyl group). The above R 42 Substituents for saturated hydrocarbon groups having 1 to 6 carbon atoms and aryl groups having 6 to 12 carbon atoms include saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, and halogen atoms.

[0019] The phenol in formula (4) above is preferably at least one selected from the group consisting of orthocresol and 2,5-dimethylphenol.

[0020] The polyphenylene ether of this embodiment contains, with a total of 100 mol% of repeating units derived from phenol of formula (1), repeating units derived from phenol of formula (2), and repeating units derived from phenol of formula (4), 5 to 50 mol% of repeating units derived from phenol of formula (1), 25 to 75 mol% of repeating units derived from phenol of formula (2), and 5 to 60 mol% of repeating units derived from phenol of formula (4). From the viewpoint of obtaining a polyphenylene ether with a low dielectric loss tangent, the repeating units derived from phenol of formula (1) are preferably 7 to 48 mol%, and more preferably 10 to 45 mol%, relative to the total of 100 mol% of the repeating units derived from phenol of formula (1), formula (2), and formula (4). From a similar viewpoint, the repeating units derived from phenol of formula (2) are preferably 28 to 72 mol%, and more preferably 30 to 70 mol%, relative to the total of 100 mol% of the repeating units derived from phenol of formula (1), formula (2), and formula (4). From a similar viewpoint, the repeating units derived from phenol of formula (4) are preferably 7 to 58 mol%, and more preferably 10 to 55 mol%, relative to the total of 100 mol% of the repeating units derived from phenol of formula (1), formula (2), and formula (4).

[0021] In this embodiment, the total moles of the repeating units derived from phenol of formula (1), formula (2), and formula (4) are preferably 75 mol% or more, more preferably 90 mol% or more, and even more preferably 95 mol% or more, relative to 100 mol% of polyphenylene ether.

[0022] Since the phenol in formula (1) does not have an unsubstituted ortho position (i.e., hydrogen atoms are not bonded to the two ortho carbon atoms of the carbon atom to which the hydroxyl group is bonded), it can react with other phenolic monomers only at the phenolic hydroxyl group and the para carbon atom. Therefore, the repeating units derived from formula (1) include repeating units having the structure of formula (9) below. [ka] (In formula (9), R 11 and R 12 This is the same as equation (1).

[0023] The phenol of formula (2) can react with another phenolic monomer at either the ortho or para position of the phenol, in addition to the phenolic hydroxyl group. Therefore, repeating units derived from the phenol of formula (2) have the structures of formula (10), formula (11), or combinations thereof. [ka] [ka] (In formulas (10) and (11), R 21 , R 22 This is the same as equation (2).

[0024] The phenol of formula (4), like the phenol of formula (2), can react with another phenolic monomer at either the ortho or para position of the phenol, in addition to the phenolic hydroxyl group. Therefore, repeating units derived from the phenol of formula (4) have the structures of formulas (12) and (13) below, or combinations thereof. [ka] [ka] (In formulas (12) and (13), R 41 , R 42 This is the same as equation (4).

[0025] The polyphenylene ether in this embodiment may contain, in addition to the phenol of formula (1), the phenol of formula (2), and the phenol of formula (4), a quaternary copolymer containing a structure derived from the divalent phenol of formula (14) below as an impurity (in this specification, sometimes simply referred to as "impurity A"). The polyphenylene ether in this embodiment may be a mixture of the above polyphenylene ether and the above impurity A. The molar ratio of impurity A to 100 mol% of the polyphenylene ether in this embodiment is preferably 10 mol% or less, and more preferably 5 mol% or less. The above impurity A can be synthesized, for example, as a quaternary copolymer containing a structure derived from a divalent phenol with z=0 in formula (14) by the reaction of the following formula (15), which is generated as a byproduct during the oxidative polymerization of a monovalent phenol, with a polyphenylene ether composed of a monovalent phenol. [ka] (In formula (14), R 11 and R 12 This is the same as equation (1). z is 0 or 1, and Y is [ka] (In the formula, R 51 Each of these is independently one of the following: a hydrocarbon group having 1 to 6 carbon atoms (which may be substituted), an aryl group having 6 to 12 carbon atoms (which may be substituted), or a halogen atom. [ka] (In formula (15), R 11 and R 12 This is the same as equation (1).

[0026] The polyphenylene ether in this embodiment may be a modified polyphenylene ether in which the hydroxyl groups contained in the polyphenylene ether are modified into functional groups (for example, functional groups containing unsaturated carbon bonds).

[0027] The polyphenylene ether in this embodiment may have at least one substructure from the group consisting of the following formulas (5), (6), (7), and (8). [ka] [ka] [ka] (In formula (7), R 7 (This refers to a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated hydrocarbon may have substituents to the extent that it satisfies the condition of having 1 to 10 carbon atoms.) [ka] (In formula (8), R 81 R is a saturated or unsaturated divalent hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated divalent hydrocarbon may have substituents to the extent that it satisfies the condition of having 1 to 10 carbon atoms. 82 (This is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated hydrocarbon may have substituents to the extent that it satisfies the condition of having 1 to 10 carbon atoms.) Furthermore, at least one substructure selected from the group consisting of formulas (5), (6), (7), and (8) above may be directly bonded to a hydroxyl group contained in the polyphenylene ether.

[0028] <Method for producing polyphenylene ether> The polyphenylene ether of this embodiment is obtained, for example, by a method that includes at least a step of oxidative polymerization of a monovalent phenol compound represented by formulas (1), (2), and (4) above. The oxidative polymerization step preferably involves oxidative polymerization of a raw material containing at least the phenol of formula (1), the phenol of formula (2), and the phenol of formula (4).

[0029] Examples of monovalent phenol compounds represented by the above formula (1) 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. In particular, 2,6-dimethylphenol, 2,3,6-trimethylphenol, and 2,6-diphenylphenol are preferred because they are inexpensive and readily available. The monovalent phenol compound represented by formula (1) above may be used individually or in combination of multiple types.

[0030] Examples of monovalent phenol compounds represented by formula (2) above include 2-isopropyl-5-methylphenol, 2-cyclohexyl-5-methylphenol, 2-tert-butyl-5-methylphenol, and 2-isobutyl-5-methylphenol. From the viewpoint of suppressing multi-branching and gelation, bulky substituents such as 2-t-butyl-5-methylphenol and 2-cyclohexyl-5-methylphenol are more preferred. The monovalent phenol compound represented by formula (2) above may be used individually or in combination of multiple types.

[0031] Examples of monovalent phenol compounds represented by formula (4) above include o-cresol, 2-ethylphenol, 2-phenylphenol, 2,3-dimethylphenol, 2,5-dimethylphenol, 2-methyl-3-ethylphenol, 2-methyl-5-ethylphenol, 2-methyl-5-n-propylphenol, 2-methyl-5-chlorophenol, 2-methyl-5-bromophenol, 2,5-diethylphenol, 2-ethyl-5-n-propylphenol, 2-methyl-5-n-butylphenol, 2,5-di-n-propylphenol, 2-ethyl-5-chlorophenol, 2-ethyl-5-bromophenol, 2-methyl-5-phenylphenol, 2,5-diphenylphenol, 2-methyl-5-tolylphenol, 2,5-ditolylphenol, and 2,3,5-dimethylphenol. Among these, o-cresol and 2,5-dimethylphenol are particularly preferred because they are inexpensive and readily available. The monovalent phenol compound represented by formula (4) above may be used individually or in combination of multiple types.

[0032] Typically, in the oxidative polymerization of phenols having a hydrogen atom in the ortho position represented by formula (4) above (e.g., 2-methylphenol, 2,5-dimethylphenol, 2-phenylphenol), ether bonds can be formed even at the ortho position. This makes it difficult to control the bonding position of the phenol compound during oxidative polymerization, resulting in high molecular weight polymers polymerized in a branched manner with an average of 3 or more hydroxyl groups per molecule, ultimately generating a gel component that is insoluble in solvents (see Reference Example 1 below for the oxidative polymerization of 2,5-dimethylphenol and 2,6-dimethylphenol). On the other hand, when a phenol having a bulky substituent at one ortho position represented by formula (2) is used, even though a hydrogen atom is present at the opposite ortho position, it becomes possible to control the bonding position of the phenol compound during oxidative polymerization, and a polyphenylene ether with an average of less than 2.5 hydroxyl groups per molecule can be obtained. When a phenol having a bulky substituent at one ortho position represented by formula (2) is used, even when a monovalent phenol having the phenol represented by formula (4) is used as the third component, gelation does not occur, and a polyphenylene ether with an average of less than 2.5 hydroxyl groups per molecule can be obtained.

[0033] As the polymerization catalyst used in this embodiment, any known catalyst system that can be used in the production of polyphenylene ethers can be used. Commonly known catalyst systems consist of a transition metal ion having redox activity and an amine compound that can form a complex with the transition metal ion. Examples include catalyst systems consisting of a copper compound and an amine compound, a catalyst system consisting of a manganese compound and an amine compound, a catalyst system consisting of a cobalt compound and an amine compound, and so on. Since the polymerization reaction proceeds efficiently under slightly alkaline conditions, a small amount of alkali or further amine compounds may be added.

[0034] The polymerization catalyst preferred in this embodiment is a catalyst comprising 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 (16) as the amine compound. [ka] In formula (16), R 16 , R 17 , R 18 , R 19 Each of these is independently a hydrogen atom and a linear or branched alkyl group having 1 to 6 carbon atoms, and not all of them are hydrogen atoms at the same time. 20 This is an alkylene group having 2 to 5 carbon atoms and being linear or methyl-branched.

[0035] Examples of copper compounds used as catalyst components are listed below. Suitable copper compounds include cuprous compounds, cupric compounds, or mixtures thereof. Examples of cupric compounds include cupric chloride, cupric bromide, cupric sulfate, and cupric nitrate. Examples of cuprous compounds include cuprous chloride, cuprous bromide, cuprous sulfate, and cuprous nitrate. Among these, particularly preferred metallic compounds are cuprous chloride, cupric chloride, cuprous bromide, and cupric bromide. These copper salts may also be synthesized at the time of use from oxides (e.g., cuprous oxide), carbonates, hydroxides, and corresponding halogens or acids. A frequently used method is to prepare them by mixing the previously exemplified cuprous oxide with hydrogen halides (or solutions of hydrogen halides).

[0036] 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 can be used as aqueous solutions or in solutions with a suitable solvent. These halogen compounds can be used individually or in combination of two or more. Preferred halogen compounds are aqueous solutions of hydrogen chloride and aqueous solutions of hydrogen bromide.

[0037] The amount of these compounds used is not particularly limited, but it is preferable that the amount of halogen atoms be between 2 and 20 times the amount of copper atoms, and the preferred amount of copper atoms to be used per 100 moles of phenol compound added to the polymerization reaction is in the range of 0.02 moles to 0.6 moles.

[0038] Next, we list examples of diamine compounds that serve as catalyst components. For example, 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 Examples include methyl ethylenediamine, N,N'-n-butylethylenediamine, Ni-butylethylenediamine, N,N'-i-butylethylenediamine, Nt-butylethylenediamine, N,N'-t-butylethylenediamine, 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. For this embodiment, preferred diamine compounds are those in which the alkylene group connecting the two nitrogen atoms has two or three carbon atoms. The amount of these diamine compounds used is not particularly limited, but it is preferably in the range of 0.01 moles to 10 moles per 100 moles of the phenol compound added to the polymerization reaction.

[0039] In this embodiment, the polymerization catalyst may include primary amines and secondary monoamines as constituent components. Examples of secondary monoamines, but not limited to the following, include 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.

[0040] The polymerization catalyst in this embodiment may also include a tertiary monoamine compound. A tertiary monoamine compound is an aliphatic tertiary amine, including alicyclic tertiary amines. Examples include trimethylamine, triethylamine, tripropylamine, tributylamine, triisobutylamine, dimethylethylamine, dimethylpropylamine, allyldiethylamine, dimethyl-n-butylamine, diethylisopropylamine, and N-methylcyclohexylamine. These tertiary monoamines may be used individually or in combination of two or more types. The amount used is not particularly limited, but it is preferably in the range of 15 moles or less per 100 moles of the phenol compound added to the polymerization reaction.

[0041] In this embodiment, there are no limitations on adding surfactants that are conventionally known to have an effect of improving polymerization activity. Examples of such surfactants include trioctylmethylammonium chloride, known by the trade names Aliquat 336 and Capriquat. The amount used is preferably in a range not exceeding 0.1% by mass relative to 100% by mass of the total amount of the polymerization reaction mixture.

[0042] In this embodiment, the oxygen-containing gas used in polymerization can be pure oxygen, a mixture of oxygen and an inert gas such as nitrogen in any proportion, air, or a mixture of air and an inert gas such as nitrogen in any proportion. While atmospheric pressure is sufficient for the system pressure during the polymerization reaction, it can be reduced or increased as needed.

[0043] The polymerization temperature is not particularly limited, but if it is too low, the reaction will not proceed easily, and if it is too high, the reaction selectivity may decrease or a gel may form. Therefore, it is in the range of 0 to 60°C, preferably 10 to 45°C.

[0044] In the method for producing polyphenylene ether, polymerization can also be carried out in a poor solvent such as alcohol.

[0045] (Copper extraction and by-product removal process) In this embodiment, there are no particular restrictions on the post-treatment method after the polymerization reaction is completed. Typically, an acid such as hydrochloric acid or acetic acid, or ethylenediaminetetraacetic acid (EDTA) and its salts, iminodiacetic acid and its salts, nitrilotriacetic acid and its salts, etc., are added to the reaction solution to deactivate the catalyst. In addition, the removal of divalent phenol by-products generated by the polymerization of polyphenylene ether can be carried out using conventionally known methods. If the metal ions that act as catalysts are substantially deactivated as described above, the mixture can be decolorized simply by heating it. Alternatively, it is also possible to add the required amount of a known reducing agent. Examples of known reducing agents include hydroquinone and sodium dithionite.

[0046] (Liquid-liquid separation process) In the method for producing polyphenylene ether, water may be added to extract the compound from which the copper catalyst has been deactivated, followed by liquid-liquid separation into an organic phase and an aqueous phase. The copper catalyst may then be removed from the organic phase by removing the aqueous phase. This liquid-liquid separation step is not particularly limited, but examples include static separation and separation by centrifugation. To promote the above liquid-liquid separation, known surfactants may be used.

[0047] (concentration / drying process) Next, in the method for producing polyphenylene ether according to this embodiment, the organic phase containing the polyphenylene ether after liquid-liquid separation may be concentrated and dried by volatilizing the solvent.

[0048] Methods for volatilizing the solvent contained in the organic phase are not particularly limited, but include methods such as transferring the organic phase to a high-temperature concentration tank and distilling off the solvent to concentrate it, or using equipment such as a rotary evaporator to distill off toluene and concentrate it.

[0049] The drying temperature in the drying process is preferably at least 60°C, more preferably 80°C or higher, even more preferably 120°C or higher, and most preferably 140°C or higher. Drying polyphenylene ether at a temperature of 60°C or higher efficiently reduces the content of high-boiling point volatile components in the polyphenylene ether powder.

[0050] To efficiently obtain polyphenylene ether, methods such as increasing the drying temperature, increasing the vacuum level in the drying atmosphere, and stirring during drying are effective, but increasing the drying temperature is particularly preferable from the viewpoint of manufacturing efficiency. In the drying process, it is preferable to use a dryer equipped with a mixing function. Examples of mixing functions include agitation type and tumbling type dryers. This allows for a larger processing volume and maintains high productivity.

[0051] The polyphenylene ether of this embodiment can also be produced by a redistribution reaction in which the polyphenylene ether derived from the phenol of formula (1) is equilibrated with the phenol compound of formula (2) and the phenol compound of formula (4) in the presence of an oxidizing agent. The redistribution reaction is known in the art and is described, for example, in U.S. Patent No. 3,496,236 by Cooper et al. and U.S. Patent No. 5,880,221 by Liska et al.

[0052] (Denaturation reaction process) There are no limitations on the method for introducing functional groups to the hydroxyl groups of unmodified polyphenylene ether. For example, it can be obtained by the formation of an ester bond between the hydroxyl groups of unmodified polyphenylene ether and a carboxylic acid having a carbon-carbon double bond (hereinafter referred to as carboxylic acid). Various known methods can be used to form the ester bond. For example, a. reaction between a carboxylic acid halide and the hydroxyl group at the polymer end, b. formation of an ester bond by reaction with a carboxylic acid anhydride, c. direct reaction with a carboxylic acid, d. transesterification reaction, etc. Method a., reaction with a carboxylic acid halide is one of the most common methods. As the carboxylic acid halide, chlorides and bromides are commonly used, but other halogens may also be used. The reaction may be a direct reaction with the hydroxyl group or a reaction with an alkali metal salt of the hydroxyl group. Since acids such as hydrogen halides are generated in the direct reaction between a carboxylic acid halide and the hydroxyl group, a weak base such as an amine may be present to trap the acid. In the reaction with carboxylic acid anhydride (b) and the direct reaction with carboxylic acid (c), compounds such as carbodiimides or dimethylaminopyridine may be present to activate the reaction site and promote the reaction. In the case of the transesterification reaction (d), it is desirable to remove the alcohols produced as needed. Known metal catalysts may also be present to promote the reaction. After the reaction, the polymer solution 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 an alcohol and the target product may be recovered by reprecipitation. Alternatively, after washing the polymer solution, the solvent may be removed under reduced pressure and the polymer may be recovered.

[0053] The method for producing modified polyphenylene ether according to this embodiment is not limited to the method for producing polyphenylene ether described above, and the order and number of times of the above-described oxidative polymerization step, copper extraction and by-product removal step, liquid-liquid separation step, and concentration and drying step may be adjusted as appropriate.

[0054] <Thermosetting composition> The polyphenylene ether of this embodiment can be used as a raw material for a thermosetting composition. The thermosetting composition is not particularly limited as long as it contains the polyphenylene ether of this embodiment as described above, but it preferably further contains a crosslinking agent and an organic peroxide, and optionally further contains a thermoplastic resin, a flame retardant, other additives, silica filler, solvent, etc. The components of the thermosetting composition of this embodiment are described below.

[0055] (Polyphenylene ether) As described above, the polyphenylene ether contained in the thermosetting composition of this embodiment may be used as a resin alone, in combination with other polyphenylene ethers having different structures, or in combination with various known additives. When used in combination with other components, the content of polyphenylene ether in the thermosetting composition is preferably 0.5 to 95% by mass, more preferably 20 to 93% by mass, and even more preferably 40 to 90% by mass.

[0056] (Crosslinking agent) In the thermosetting composition of this embodiment, any crosslinking agent having the ability to cause or promote a crosslinking reaction can be used. The crosslinking agent preferably has a number-average molecular weight of 4,000 or less. When the number-average molecular weight of the crosslinking agent is 4,000 or less, the increase in viscosity of the thermosetting composition can be suppressed, and good resin fluidity can be obtained during heat molding. The number-average molecular weight is often a value measured using a general molecular weight measurement method, specifically a value measured using GPC.

[0057] From the viewpoint of crosslinking reaction, the crosslinking agent preferably has an average of two or more carbon-carbon unsaturated double bonds per molecule. The crosslinking agent may consist of one type of compound or two or more types of compounds. In this specification, "carbon-carbon unsaturated double bond" refers to a double bond located at the branched end of the main chain when the crosslinking agent is a polymer or oligomer. An example of a carbon-carbon unsaturated double bond is the 1,2-vinyl bond in polybutadiene.

[0058] When the number-average molecular weight of the crosslinking agent is less than 600, the number of carbon-carbon unsaturated double bonds per molecule of the crosslinking agent (average value) 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 of carbon-carbon unsaturated double bonds per molecule of the crosslinking agent (average value) 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 of carbon-carbon unsaturated double bonds per molecule of the crosslinking agent (average value) is preferably 26 to 60. When the number-average molecular weight of the crosslinking agent is within the above range, having the number of carbon-carbon unsaturated double bonds equal to or greater than the specified value further enhances the reactivity of the crosslinking agent in the thermosetting composition of this embodiment, further improves the crosslinking density of the cured product of the thermosetting composition, and as a result can provide even better heat resistance. On the other hand, when the number-average molecular weight of the crosslinking agent is within the above range, having the number of carbon-carbon unsaturated double bonds equal to or less than the specified value further enhances the resin fluidity during heat molding.

[0059] Examples of crosslinking agents include triallyl isocyanurate compounds such as triallyl isocyanurate (TAIC), triallyl 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, vinyl benzyl 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'-bismaleimidediphenylmethane. These crosslinking agents can be used individually or in combination of two or more. Among these, it is preferable that the crosslinking agent contains at least one compound selected from the group consisting of triallyl cyanurate, triallyl isocyanurate, and polybutadiene. By including at least one of the compounds described above as a crosslinking agent, the thermosetting composition exhibits improved compatibility and coating properties between the crosslinking agent and polyphenylene ether, and tends to exhibit improved substrate properties when mounted on an electronic circuit board.

[0060] The mass ratio of polyphenylene ether to crosslinking agent (polyphenylene ether:crosslinking agent) is preferably 25:75 to 95:5, and more preferably 32:68 to 85:15, from the viewpoint of further improving the compatibility between the crosslinking agent and modified polyphenylene ether, the coatability of the thermosetting composition, and the properties of the mounted electronic circuit board.

[0061] (organic peroxide) In this embodiment, any organic peroxide having the ability to promote the polymerization reaction of a thermosetting composition containing polyphenylene ether and a crosslinking agent 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)hexine-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. Furthermore, radical generators such as 2,3-dimethyl-2,3-diphenylbutane can also be used as reaction initiators for thermosetting compositions. Among these, 2,5-dimethyl-2,5-di(t-butylperoxy)hexine-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 with excellent heat resistance and mechanical properties, and furthermore, a low dielectric loss tangent (and preferably a low dielectric constant).

[0062] The 1-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. Having the 1-minute half-life temperature of the organic peroxide within the range of 155 to 185°C tends to result in improved compatibility between the organic peroxide and modified PPE, better coating properties of the thermosetting composition, and superior characteristics of the mounted electronic circuit board. In this specification, the 1-minute half-life temperature is defined as the temperature at which the time required for an organic peroxide to decompose and its amount of reactive oxygen species to be halved is 1 minute. The 1-minute half-life temperature is determined by dissolving an organic peroxide in a radical-inert solvent, such as benzene, at a concentration of 0.05 to 0.1 mol / L, and then thermally decomposing the organic peroxide solution under a nitrogen atmosphere.

[0063] Examples of organic peroxides with a 1-minute half-life temperature in the range of 155-185°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-butylperoxy-2-ethylhexyl monocarbonate (161.4°C), t-hexylperoxybenzoate (160.3°C), and 2,5-dimethyl-2,5-di(benzoylperoxy)hexane (158.2°C). Examples include t-butylperoxyacetate (159.9°C), 2,2-di-(t-butylperoxy)butane (159.9°C), t-butylperoxybenzoate (166.8°C), n-butyl4,4-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).

[0064] The content of the organic peroxide 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 even more preferably 1.5 parts by mass or more, based on 100 parts by mass of the total of the polyphenylene ether and the crosslinking agent, from the viewpoint of further improving the compatibility between the organic peroxide and modified PPE and the coating properties of the thermosetting composition, and preferably 5 parts by mass or less, more preferably 4.5 parts by mass or less, from the viewpoint of having excellent substrate properties when the thermosetting composition is mounted on an electronic circuit board.

[0065] (thermoplastic resin) The thermoplastic resin is preferably at least one selected from the group consisting of block copolymers of vinyl aromatic compounds and olefin-based alkene compounds and their hydrogenated products (hydrogenated block copolymers obtained by hydrogenating block copolymers of vinyl aromatic compounds and olefin-based alkene compounds), and homopolymers of vinyl aromatic compounds. Furthermore, the weight-average molecular weight of the thermoplastic resin is preferably 50,000 to 780,000, more preferably 60,000 to 750,000, and even more preferably 70,000 to 700,000, from the viewpoint of further improving compatibility with polyphenylene ether, resin fluidity, coatability of thermosetting compositions, and heat resistance during curing. When a thermosetting composition contains polyphenylene ether, a crosslinking agent, and an organic peroxide, along with a thermoplastic resin having the type and weight-average molecular weight described above, it tends to have good compatibility between modified PPE and other components, as well as good coating properties for substrates, and consequently, may also have excellent substrate properties when incorporated into an electronic circuit board.

[0066] The content of units derived from vinyl aromatic compounds 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, and 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, and 67% by mass or less. When the content of units derived from vinyl aromatic compounds in the block copolymer or its hydrogenated product is 20 to 70% by mass, the compatibility with modified polyphenylene ether is further improved and / or the adhesion strength with metal foil tends to be further improved.

[0067] Examples of vinyl aromatic compounds include those having an aromatic ring and a vinyl group in their molecule, such as styrene. The olefinic alkene compound can be any alkene having a linear or branched structure within the molecule, such as ethylene, propylene, butylene, isobutylene, butadiene, and isoprene. As for the thermoplastic resin, from the viewpoint of having even better compatibility with polyphenylene ether, it is preferable that it be at least one selected from the group consisting of styrene-butadiene block copolymer, styrene-ethylene-butadiene block copolymer, styrene-ethylene-butylene block copolymer, styrene-butadiene-butylene block copolymer, styrene-isoprene block copolymer, styrene-ethylene-propylene block copolymer, styrene-isobutylene block copolymer, hydrogenated styrene-butadiene block copolymer, hydrogenated styrene-ethylene-butadiene block copolymer, hydrogenated styrene-butadiene-butylene block copolymer, hydrogenated styrene-isoprene block copolymer, and styrene homopolymer (polystyrene), and more preferably one or more selected from the group consisting of styrene-butadiene block copolymer, hydrogenated styrene-butadiene block copolymer, and polystyrene.

[0068] The hydrogenation rate in the above-mentioned hydrogenated product is not particularly limited, and some carbon-carbon unsaturated double bonds derived from the olefinic alkene compound may remain.

[0069] The content of the thermoplastic resin is preferably 2 to 20 parts by mass, more preferably 3 to 19 parts by mass, even more 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 and the crosslinking agent. When this content is within the above numerical range, the thermosetting composition of this embodiment exhibits even better compatibility and coating properties between the thermoplastic resin and the modified polyphenylene ether, and tends to exhibit even better substrate characteristics when mounted on an electronic circuit board.

[0070] Furthermore, the thermosetting composition of this embodiment may also include thermoplastic resins other than those described above, having the same type and weight-average molecular weight.

[0071] (Flame retardant) The thermosetting composition of this embodiment preferably contains a flame retardant. The flame retardant is not particularly limited as long as it is incompatible with other components in the thermosetting composition after curing, from the viewpoint of improving heat resistance. Preferably, the flame retardant is incompatible with the polyphenylene ether and / or crosslinking agent in the thermosetting composition after curing. Examples of flame retardants include inorganic flame retardants such as antimony trioxide, aluminum hydroxide, magnesium hydroxide, and zinc borate; aromatic bromine compounds such as hexabromobenzene, decabromodiphenylethane, 4,4-dibromoviphenyl, and ethylenebistetrabromophthalimide; and phosphorus-based flame retardants such as resorcinol bis-diphenyl phosphate and resorcinol bis-dixylenyl phosphate. These flame retardants may be used individually or in combination of two or more. Among these, decabromodiphenylethane is preferred as the flame retardant from the viewpoint of superior compatibility between the flame retardant and modified PPE, coating properties of the thermosetting composition, and characteristics of the mounted electronic circuit board.

[0072] The amount of 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, per 100 parts by mass of the total of the polyphenylene ether resin and the crosslinking agent. Furthermore, from the viewpoint of maintaining a low dielectric loss tangent of the resulting cured product (and preferably also maintaining a low dielectric constant), the amount of 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.

[0073] (Silica filler) The thermosetting composition of this embodiment may contain silica fillers. Examples of silica fillers include natural silica, fused silica, synthetic silica, amorphous silica, aerosil, and hollow silica. The silica filler content may be 10 to 100 parts by mass per 100 parts by mass of the total of the polyphenylene ether resin and the crosslinking agent. Furthermore, the silica filler may be surface-treated with a silane coupling agent or the like.

[0074] The thermosetting composition of this embodiment may further contain additives such as heat stabilizers, antioxidants, UV absorbers, surfactants, lubricants, solvents, etc., in addition to flame retardants and silica fillers. When the thermosetting composition of this embodiment contains a solvent, it may 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 this embodiment.

[0075] (solvent) From the viewpoint of solubility, preferred solvents include aromatic compounds such as toluene and xylene, methyl ethyl ketone (MEK), cyclopentanone, cyclohexanone, and chloroform. These solvents may be used individually or in combination of two or more.

[0076] <Prepreg> The prepreg of this embodiment comprises a substrate and the thermosetting composition of this embodiment described above, and is preferably a composite comprising the substrate and the thermosetting composition of this embodiment impregnated or coated onto the substrate. The prepreg can be obtained, for example, by impregnating a substrate such as glass cloth with a varnish of the thermosetting composition, and then drying off the solvent using a hot air dryer or the like.

[0077] Examples of substrates 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, kraft paper, cotton paper, and cloths obtained from paper-glass blended yarns; and polytetrafluoroethylene porous films. Glass cloth is preferred among these. These substrates may be used individually or in combination of two or more.

[0078] The proportion of the thermosetting composition solids (components of the thermosetting composition other than the solvent) in the prepreg of this embodiment is preferably 30 to 80% by mass, and more preferably 40 to 70% by mass. When the above proportion is 30% by mass or more, the insulation reliability tends to be even better when the prepreg is used for electronic circuit boards, etc. When the above proportion is 80% by mass or less, the mechanical properties such as the flexural modulus tend to be even better in applications such as electronic circuit boards.

[0079] <Laminate> The laminate of this embodiment preferably comprises a cured prepreg of this embodiment and a metal foil, and is a metal-clad laminate obtained by laminating and curing the thermosetting composition of this embodiment or the prepreg of this embodiment and the metal foil. The metal-clad laminate preferably has a form in which the cured prepreg (hereinafter also referred to as the "cured composite") and the metal foil are laminated and in close contact, and is suitably used as a material for electronic substrates. Examples of metal foils include aluminum foil and copper foil, and among these, copper foil is preferred because of its low electrical resistance. The cured composite material combined with metal foil can consist of one or multiple sheets, and depending on the application, the metal foil is layered on one or both sides of the composite material to form a laminate.

[0080] One method for manufacturing a metal-clad laminate is to form a composite (e.g., the prepreg described above) consisting of a thermosetting composition and a substrate, then layer this with a metal foil, and finally cure the thermosetting composition to obtain a laminate in which a cured laminate and a metal foil are laminated together. One particularly preferred application of the above-mentioned metal-clad laminate is a printed circuit board. Preferably, in a printed circuit board, at least a portion of the metal foil is removed from the metal-clad laminate.

[0081] <Printed wiring board> A printed circuit board can be obtained by removing at least a portion of the metal foil from the above-mentioned metal-clad laminate. The above-mentioned printed circuit board can typically be formed by a pressure-heat molding method using the prepreg of this embodiment described above. The base material can be the same as that described above regarding the prepreg. The printed circuit board described above, by containing the thermosetting composition of this embodiment, has excellent heat resistance and electrical properties (low dielectric loss tangent and / or low dielectric constant), can further suppress fluctuations in electrical properties due to environmental changes, and has excellent insulation reliability and mechanical properties. [Examples]

[0082] The embodiment will be described in more detail below based on the following examples, but this embodiment is not limited to the following examples.

[0083] First, the measurement methods and evaluation criteria for each physical property are described below.

[0084] (1) Number average molecular weight (Mn) A gel permeation chromatography system 21 manufactured by Showa Denko K.K. was used as the measuring device. Calibration curves were created using standard polystyrene and ethylbenzene, and the number-average molecular weight (Mn) of the obtained modified polyphenylene ethers was measured using these calibration curves. The standard polystyrenes used had molecular weights of 3,650,000, 2,170,000, 1,090,000, 681,000, 204,000, 52,000, 30,200, 13,800, 3,360, 1,300, and 550. The column used consisted of two Showa Denko K-805L columns connected in series. Chloroform was used as the solvent, with a solvent flow rate of 1.0 mL / min and a column temperature of 40°C. A 1 g / L chloroform solution of modified polyphenylene ether was prepared and used as the sample for measurement. The UV wavelength of the detection unit was set to 254 nm for standard polystyrene and 283 nm for polyphenylene ether. Based on the above measurement data, the number-average molecular weight (Mn) (g / mol) was calculated from the percentage of peak areas on the curve showing the molecular weight distribution obtained by GPC.

[0085] (2) Dielectric loss 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 using the cavity resonance method. A network analyzer (N5230A, Agilent Technologies) and a cavity resonator (Cavity Resornator CP series) manufactured by Kanto Electronics Applied Development Co., Ltd. were used as the measuring equipment. The laminates were cut into strips approximately 2 mm wide, 50 mm long, and 0.5 mm thick, with the warp threads of the glass cloth as the longer side. Next, they were dried in an oven at 105°C ± 2°C for 2 hours, and then left to stand for 24 ± 5 ​​hours in an environment of 23°C and 50 ± 5% relative humidity. After that, the dielectric loss tangent was measured using the above measuring equipment in an environment of 23°C and 50 ± 5% relative humidity.

[0086] The following describes the methods for producing polyphenylene ether in each example and comparative example.

[0087] (Example 1) A 40-liter jacketed polymerization tank, equipped with a sparger, stirring turbine blades, and baffles at the bottom for introducing oxygen-containing gas, and a reflux condenser in the vent gas line at the top of the polymerization tank, was mixed with 3.2 g of cupric oxide, 24.3 g of 47% by mass aqueous solution of hydrogen bromide, 7.8 g of di-t-butylethylenediamine, 37.7 g of di-n-butylamine, 114.7 g of butyldimethylamine, 17.8 kg of toluene, 336 g of 2,6-dimethylphenol, 773 g of 2-tert-butyl-5-methylphenol, and 891 g of o-cresol to form a homogeneous solution. Next, dry air was introduced into the polymerization tank through the sparger at a rate of 21.0 L / min to start polymerization. Dry air was passed through for 120 minutes to obtain the polymerization mixture. The internal temperature was controlled to 45°C during polymerization. The polymerization mixture (polymerization solution) at the end of polymerization was in a homogeneous solution state. The supply of dry air was stopped, and 45.2 g of tetrasodium ethylenediaminetetraacetate (reagent manufactured by Tokyo Chemical Industry Co., Ltd.) was added to the polymerization mixture as an aqueous solution in 2 kg of water. The polymerization mixture was stirred at 70°C for 180 minutes, then allowed to stand for 20 minutes, and the organic phase and aqueous phase were separated by liquid-liquid separation. The organic phase was concentrated using a rotary evaporator to remove toluene. Then, it was dried in a dryer at 140°C and 1 mmHg for 120 minutes to obtain dry polyphenylene ether. The obtained dried polyphenylene ether was subjected to the measurements described above. The obtained dried polyphenylene ether was prepared as a 40% by mass toluene solution and used as the stock solution for the denaturation reaction. A 300 mL three-necked round-bottom flask was used as the denaturation reactor, equipped with a line for introducing nitrogen gas at the top and a reflux condenser on the vent gas line at the top of the reactor. In a 300 mL three-necked flask whose interior was purged with nitrogen, 100 g of a solution of dried polyphenylene ether (undenatured polyphenylene ether solution) prepared to be a 40% by mass toluene solution, 21.40 g of 48% sodium hydroxide aqueous solution, and 0.77 g of tetrabutylammonium bromide were added. Then, 14.49 mL of 4-(chloromethyl)styrene was taken into a syringe and added dropwise to the system at room temperature while stirring. The flask was heated in an oil bath and stirring was continued at 80°C. After 4 hours from the start of stirring at 90°C, heating was stopped, and after returning to room temperature, the reaction was stopped with 10% hydrochloric acid aqueous solution to adjust the pH of the solution to 7. 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 then washed with methanol in an amount that resulted in a ratio of 2.5 to the wet polyphenylene ether. This washing procedure was repeated three times. Next, the wet polyphenylene ether was maintained at 100°C and 1 mmHg for 8 hours to obtain a dried, modified polyphenylene ether. ¹H NMR measurement confirmed the presence of a proton peak derived from the olefin of the vinylbenzyl group, leading to the conclusion that the hydroxyl group had been modified into a vinylbenzyl group. Next, to 40.0 parts by mass of modified polyphenylene ether, 10.0 parts by mass of TAIC (manufactured by Nippon Chemical Corporation), 5.0 parts by mass of thermoplastic resin (ToughTec H1041, manufactured by Asahi Kasei Corporation), 0.8 parts by mass of organic peroxide (Perbutyl P, manufactured by NOF Corporation), 30.0 parts by mass of silica filler (CRS1077-EXR4, manufactured by Ryusen Co., Ltd.), and 14.2 parts by mass of flame retardant (SAYTEX8010, manufactured by Albemarle Japan Co., Ltd.) were added to toluene, stirred, and dissolved to obtain a varnish (solid content concentration 70% by mass). After impregnating this varnish with L glass cloth (manufactured by Asahi Schwebel Co., Ltd., style: 2116), the excess varnish was scraped off by passing it through a predetermined slit, and the mixture was dried in a drying oven at 105°C for a predetermined time to remove the toluene and obtain a prepreg. The prepreg was cut to a predetermined size, and by comparing its mass with that of glass cloth of the same size, the solid content of the thermosetting composition in the prepreg was calculated to be 56% by mass. A copper-clad laminate was obtained by stacking a predetermined number of these prepregs, and then applying copper foil (manufactured by Furukawa Electric Industry Co., Ltd., 35 μm thick, GTS-MP foil) to both sides of the stacked prepregs, and then performing a vacuum press. In this vacuum pressing process, first, the material was heated from room temperature at a heating rate of 2°C / min while applying a pressure of 40 kg / cm². 2 The conditions are as follows: After the temperature reaches 200°C, the temperature is maintained at 200°C while the pressure is 40 kg / cm². 2 The conditions of a 60-minute duration were also adopted. Next, a laminate (approximately 0.5 mm thick) was obtained by removing the copper foil from the copper-clad laminate by etching. The dielectric properties of the laminate obtained by the method described above were measured. The results of each analysis are shown in Table 1.

[0088] (Example 2) The procedure was carried out in the same manner as in Example 1, except that the phenolic raw materials were 689 g of 2,6-dimethylphenol, 1158 g of 2-tert-butyl-5-methylphenol, and 152 g of o-cresol. The results of each analysis are shown in Table 1.

[0089] (Example 3) The procedure was carried out in the same manner as in Example 1, except that the phenolic raw materials were 522 g of 2,6-dimethylphenol, 1170 g of 2-tert-butyl-5-methylphenol, and 308 g of o-cresol. The results of each analysis are shown in Table 1.

[0090] (Example 4) The procedure was carried out in the same manner as in Example 1, except that the phenolic raw materials were 178 g of 2,6-dimethylphenol, 1194 g of 2-tert-butyl-5-methylphenol, and 628 g of o-cresol. The results of each analysis are shown in Table 1.

[0091] (Example 5) The procedure was carried out in the same manner as in Example 1, except that the phenolic raw materials were 123 g of 2,6-dimethylphenol, 1549 g of 2-tert-butyl-5-methylphenol, and 328 g of o-cresol. The results of each analysis are shown in Table 1.

[0092] (Example 6) The procedure was carried out in the same manner as in Example 1, except that the phenolic raw materials were 683 g of 2,6-dimethylphenol, 1147 g of 2-tert-butyl-5-methylphenol, and 170 g of 2,5-dimethylphenol. The results of each analysis are shown in Table 1.

[0093] (Comparative Example 1) The procedure was carried out in the same manner as in Example 1, except that the phenolic raw materials were 1626 g of 2,6-dimethylphenol and 374 g of 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane. The results of each analysis are shown in Table 1.

[0094] (Reference example 1) A 1.5-liter jacketed reactor, equipped with a sparger for introducing oxygen-containing gas at the bottom, stirring turbine blades and baffles, and a reflux condenser in the vent gas line at the top of the reactor, contained a pre-prepared mixture of 0.15 g of cuprous oxide and 1.12 g of 47% hydrogen bromide, along with 0.36 g of N,N'-di-t-butylethylenediamine, 5.31 g of dimethyl-n-butylamine, 1.74 g of di-n-butylamine, 891.3 g of toluene, 50.0 g of 2,6-dimethylphenol, and 50.0 g of 2,5-dimethylphenol. Air was then introduced into the reactor through the sparger at a rate of 1.05 L / min while vigorously stirring, and the polymerization temperature was maintained at 40°C by passing a heat transfer medium through the jacket. 120 minutes after the introduction of air, the entire solution became highly viscous and a gel formed.

[0095] [Table 1]

[0096] As shown in Table 1, by comparing with the comparative example, it was possible to obtain a laminate with a reduced dielectric loss tangent by using the polyphenylene ether of the example. [Industrial applicability]

[0097] The polyphenylene ether of the present invention has excellent dielectric properties and therefore has industrial value as an electronic material.

Claims

1. It has a repeating unit derived from phenol of formula (1) below, a repeating unit derived from phenol of formula (2) below, and a repeating unit derived from phenol of formula (4) below, A repeating unit derived from phenol of formula (1), a repeating unit derived from phenol of formula (2), and a repeating unit derived from phenol of formula (4) totaling 100 mol%, comprising: 5 to 50 mol% of the repeating unit derived from phenol of formula (1), 25 to 75 mol% of the repeating unit derived from phenol of formula (2), and 5 to 60 mol% of the repeating unit derived from phenol of formula (4). A polyphenylene ether characterized by the following features. 【Chemistry 1】 (In formula (1), R １１ Each of these is independently a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom, R １２ Each of these is independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom. 【Chemistry 2】 (In formula (2), R ２２ Each of these is independently a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom, and two R ２２ Both are not hydrogen atoms, R ２１ This is a substructure represented by the following formula (3). 【Transformation 3】 (In formula (3), R ３１ is each independently a linear alkyl group having 1 to 8 carbon atoms which may be substituted, or a cyclic alkyl structure having 1 to 8 carbon atoms to which two R ３１ are bonded, R ３２ is each independently an alkylene group having 1 to 8 carbon atoms which may be substituted, b is each independently 0 or 1, and R ３３ is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may be substituted, or a phenyl group which may be substituted.) 【Chemistry 4】 (In formula (4), R ４１ is the aforementioned R ２１ Unlike the above, R is a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom. ４２ Each of these is independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom.

2. The polyphenylene ether according to claim 1, wherein the number average molecular weight measured by gel permeation chromatography is 800 to 1492.

3. The aforementioned R ２１ The polyphenylene ether according to claim 1 or 2, comprising a repeating unit derived from a phenol of formula (2) in which is a t-butyl group.

4. The polyphenylene ether according to claim 1 or 2, wherein the phenol of formula (4) is at least one selected from the group consisting of orthocresol and 2,5-dimethylphenol.

5. The polyphenylene ether according to claim 1 or 2, having at least one substructure selected from the group consisting of formulas (5), (6), (7), and (8) below. 【Transformation 5】 【Transformation 6】 【Transformation 7】 (In formula (7), R ７ (This is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated hydrocarbon may have substituents to the extent that it satisfies the condition of having 1 to 10 carbon atoms.) 【Transformation 8】 (In formula (8), R ８１ R is a saturated or unsaturated divalent hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated divalent hydrocarbon may have substituents to the extent that it satisfies the condition of having 1 to 10 carbon atoms. ８２ (This is a hydrogen atom or a saturated or unsaturated hydrocarbon group having 1 to 10 carbon atoms, and the saturated or unsaturated hydrocarbon may have substituents to the extent that it satisfies the condition of having 1 to 10 carbon atoms.)

6. A method for producing a polyphenylene ether according to claim 1 or 2, comprising the step of carrying out oxidative polymerization of a raw material containing the phenol of formula (1), the phenol of formula (2), and the phenol of formula (4).

7. A thermosetting composition comprising the polyphenylene ether described in claim 1 or 2.

8. A prepreg comprising a substrate and the thermosetting composition described in claim 7.

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

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

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