Method for producing polyphenylene ether

Abstract

The objective is to provide a manufacturing method that can control the reaction activity during the production of polyphenylene ether while reducing the foaming time that occurs during the manufacturing process. [Solution] In order to solve the above problems, the present invention includes an oxidative polymerization step in which an oxygen-containing gas is introduced into a solution containing phenol of formula (1) and phenol of formula (2) in a polymerization reactor to perform oxidative polymerization, and a deactivation step in which a deactivator is added to deactivate the entire amount of catalyst in the polymerization reactor, wherein the deactivation step is carried out such that the polymerization time in the later stages of polymerization accounts for 40-60% of the total polymerization time of the oxidative polymerization step (100%). TIFF2026148560000018.tif31158

Description

[Technical Field]

[0001] This invention relates to a method for producing polyphenylene ether. [Background technology]

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

[0003] However, generally speaking, high molecular weight polyphenylene ethers with repeating units derived from monovalent phenols, such as 2,6-dimethylphenol, are soluble in highly toxic solvents such as chloroform, but are poorly soluble at high concentrations in aromatic solvents such as toluene, which are known as good solvents, at room temperature, and are insoluble in ketone solvents such as methyl ethyl ketone. Therefore, when used as a wiring board material, for example, handling with resin varnish solutions such as toluene or methyl ethyl ketone becomes difficult.

[0004] For example, Patent Document 1 discloses a resin composition in which a varnish is prepared by heating and melting polyphenylene ether in an aromatic solvent in order to improve the solubility and dispersibility of polyphenylene ether. Furthermore, Patent Document 2 discloses a polyphenylene ether that exhibits excellent solubility in general-purpose ketone solvents, and a thermosetting composition using the polyphenylene ether. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Patent No. 3151397 [Patent Document 2] International Publication No. 2022 / 158180 Summary of the Invention Problem to be Solved by the Invention

[0006] It is known that in oxidative polymerization of polyphenylene ether, as the molecular weight of polyphenylene ether increases, the viscosity of the reaction solution increases, so that blown oxygen-containing gas is entrapped in the solution near the liquid surface to form bubbles, and forms a bubble deposit layer (sometimes referred to as a "foam layer" herein). Therefore, when the amount of deposited bubbles (sometimes referred to as "foam amount" herein) is large and the bubbles stay for a long time, a foamy polymerization solution adheres to the inner wall of the reaction tank, which may reduce the production yield. Further, since the bubble deposit layer cannot be defoamed and continues to accumulate, the foamy polymerization solution overflows to the outside of the reaction tank and may contaminate the production process, so improvement has been desired. In order to reduce the amount of deposited bubbles, a method of reducing the charge amount of the polymerization solution relative to the volume of the reaction tank is conceivable. In this case, however, the yield of polyphenylene ether that can be produced at one time is limited, leading to a decrease in productivity. Further, in the technologies of the aforementioned Patent Documents 1 and 2, foaming that can occur in the oxidative polymerization step as described above and a method for controlling the same have not been studied, and a means for controlling the amount of deposited bubbles to be reduced is not disclosed.

[0007] The present invention has been made in view of the above problems, and an object of the present invention is to provide a production method capable of reducing the foaming time generated during the production step while controlling the reaction activity during the production of polyphenylene ether. Means for Solving the Problem

[0008] As a result of intensive studies conducted by the present inventors to solve the above-mentioned problems of the prior art, in the step of carrying out oxidative polymerization by introducing an oxygen-containing gas into a polymerization solution containing a phenol having a specific structure, the present inventors have found that by adjusting the production conditions in the late stage of polymerization after the amount of accumulated foam reaches a maximum, the reaction activity during the production of polyphenylene ether can be controlled, and the accumulated foam layer generated during the reaction can be reduced at an early stage, and thus the present invention has been completed.

[0009] That is, the present invention is as follows. [1] A method for producing a polyphenylene ether having a reduced viscosity (ηsp / c) of 0.03 to 0.30 dL / g as measured in a chloroform solution having a concentration of 0.5 g / dL at 30°C, the method comprising: an oxidative polymerization step of performing oxidative polymerization by introducing an oxygen-containing gas into a solution containing a phenol represented by the following formula (1) and a phenol represented by the following formula (2) in a polymerization reaction tank; a deactivation step of adding a deactivator that deactivates all of the catalyst in the polymerization reaction tank; wherein in the oxidative polymerization step, changes in the height of the accumulated foam layer during oxidative polymerization are observed; the oxidative polymerization step consists of an early polymerization stage from the start of oxidative polymerization until the accumulated amount of foam reaches the maximum, and a late polymerization stage from the time point when the height of the accumulated foam layer reaches the maximum to the end point of oxidative polymerization; the method for producing a polyphenylene ether is characterized in that the deactivation step is performed such that the polymerization time of the late polymerization stage accounts for 40 to 60% of the total polymerization time of the oxidative polymerization step, where the total polymerization time is taken as 100%. [Chemical formula] (In formula (1), R 11 are each independently 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, and R 12 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.) [Chemical formula] (In formula (2), each R 22 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 the two R 22 are not both hydrogen atoms, and R 21 is a partial structure represented by the following formula (3).)

Chemical Formula

[10] The phenol compound of formula (1) is 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 A method for producing polyphenylene ether according to any one of [1] to [9], characterized in that it is one or more selected from the group consisting of ,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.

[11] A method for producing polyphenylene ether according to any one of [1] to

[10] , characterized in that the phenol compound of formula (2) is one or more selected from the group consisting of 2-isopropyl-5-methylphenol, 2-cyclohexyl-5-methylphenol, 2-tert-butyl-5-methylphenol, and 2-isobutyl-5-methylphenol.

[12] A method for producing polyphenylene ether according to any one of [1] to

[11] , characterized in that the substructure represented by formula (3) is a t-butyl group.

[13] A method for producing polyphenylene ether according to any one of [1] to

[12] , characterized in that the solution further contains a phenol of the following formula (7). [ka] (In equation (7), X is a single bond or any a-valent linking group, a is an integer from 1 to 6, R 4 k is either a linear alkyl group having 1 to 8 carbon atoms or a substructure represented by formula (3) above, and k is an integer from 1 to 4, independently of the others.

[14] The phenol of formula (7) above, A phenol compound having two phenol units in its molecule, selected from the group consisting of 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,4'-methylenebis(2,6-dimethylphenol), bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxy-3,5-dimethylphenyl)sulfone, α,α'-bis(4-hydroxy-3,5-dimethylphenyl)-1,4-diisopropylbenzene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, and 1,1-bis(2-methyl-4-hydroxy-5-t-butylphenyl)butane; or; 4,4'-[(3-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(3-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 4,4'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(4-hydroxy-3-ethoxy [phenyl)methylene]bis(2,3,6-trimethylethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 2,2'-[(4-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol), 4,4'-[4-(4-hydroxyphenyl)cyclohexylidene]bis(2,6-dimethylphenol), 4,4'-[(2-hydroxyphenyl)methylene] -Bis(2,3,6-trimethylphenol), 4,4'-[1-[4-[1-(4-hydroxy-3,5-dimethylphenyl)-1-methylethyl]phenyl]ethylidene]bis(2,6-dimethylphenol), 4,4'-[1-[4-[1-(4-hydroxy-3-fluorophenyl)-1-methylethyl]phenyl]ethylidene]bis(2,6-dimethylphenol), 2,6-bis[(4-hydroxy-3,5-dimethylphenyl)ethyl]-4-methylphenol, 2,6-bis[(4-hydroxy-2,3,6-trimethylphenyl] [(4-hydroxy-3,5,6-trimethylphenyl)methyl]-4-ethylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-methylphenol, 2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-methylphenol, 2,4-bis[(4-hydroxy-3-cyclohexylphenyl)methyl]-6-methylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-cyclohexylphenol, 2,4-bis[(2-hydroxy-5-methylphenyl)methyl]-6-cyclohexylphenol, 2,4-bis[(4-hydroxy-2,3,6-trimethylphenyl)methyl]-6-cyclohexylphenol, 3,6-bis[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,2-benzenediol, 4,6-bis[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,4,6-tris[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,4,6- ris[(2-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,2'-methylenebis[6-[(4 / 2-hydroxy-2,5 / 3,6-dimethylphenyl)methyl]-4-methylphenol], 2,2'-methylenebis[6-[(4-hydroxy-3,5-dimethylphenyl)methyl]-4-methylphenol], 2,2'-methylenebis[6-[(4 / 2-hydroxy-2,3,5 / 3,4,6-trimethylphenyl)methyl]-4-methylphenol], 2,2'-methylenebis[6-[(4-hydroxy-2, 3,5-trimethylphenyl)methyl]-4-methylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxyphenyl)methyl]-6-methylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxyphenyl)methyl]-3,6-dimethylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxy-3-methylphenyl)methyl]-3,6-dimethylphenol], 4,4'-methylenebis[2-[(2,3,4-trihydroxyphenyl)methyl]-3,6-dimethylphenol], 6,6'- Chilenbis[4-[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,2,3-benzenetriol], 4,4'-cyclohexyllidenbis[2-cyclohexyl-6-[(2-hydroxy-5-methylphenyl)methyl]phenol], 4,4'-cyclohexyllidenbis[2-cyclohexyl-6-[(4-hydroxy-3,5-dimethylphenyl)methyl]phenol], 4,4'-cyclohexyllidenbis[2-cyclohexyl-6-[(4-hydroxy-2-methyl-5-cyclohexylphenyl)methyl]phenol], 4,A method for producing polyphenylene ether according to

[13] , characterized in that the phenol compound is selected from the group consisting of 4'-cyclohexyllidenebis[2-cyclohexyl-6-[(2,3,4-trihydroxyphenyl)methyl]phenol], 4,4',4'',4'''-(1,2-ethanediylidene)tetrakis(2,6-dimethylphenol), 4,4',4'',4'''-(1,4-phenylenedimethylidene)tetrakis(2,6-dimethylphenol), and 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane and has three or more phenol units in the molecule. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a method for producing polyphenylene ether that can reduce reaction activity and foam accumulation during manufacturing. [Modes for carrying out the invention]

[0011] 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.

[0012] 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 referring to "polyphenylene ether," unless otherwise inconsistent, it includes both unmodified polyphenylene ether and modified polyphenylene ether.

[0013] In this specification, A(numerical value) to B(numerical value) means A or greater and B or less. In this specification, substituents refer to, for example, saturated or unsaturated hydrocarbon groups having 1 to 10 carbon atoms, aryl groups having 6 to 10 carbon atoms, halogen atoms, etc.

[0014] (Polyphenylene ether) The polyphenylene ether produced by the method for producing polyphenylene ether of this embodiment is obtained by oxidative polymerization of the phenol of formula (1) and the phenol of formula (2) below. [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.

[0015] In the above equation (1), R 11Each of these is preferably an independently 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.

[0016] In the above equation (1), R 12 Each of these is preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and more preferably a hydrogen atom or a methyl group. In formula (1), the two R 12 These are preferably different, and more preferably one is a hydrogen atom and the other is a hydrocarbon group having 1 to 6 carbon atoms (preferably a methyl group).

[0017] 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 These are preferably different, and more preferably one is a hydrogen atom and the other is a hydrocarbon group having 1 to 6 carbon atoms (preferably a methyl group).

[0018] 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.

[0019] The raw material phenol used in this embodiment can have its structure identified by analyzing the resulting polyphenylene ether using techniques such as NMR and mass spectrometry. A specific method for identifying the structure of the polyphenylene ether involves performing field desorption mass spectrometry (FD-MS), which is known to be less prone to fragmentation, and estimating the repeating units based on the spacing of the detected ions. Furthermore, a method for estimating the structure of the polyphenylene ether can be achieved by combining electron ionization (EI) peak analysis of fragment ions with structural analysis by NMR.

[0020] In the manufacturing method according to this embodiment, from the viewpoint of solvent solubility at room temperature, it is preferable that the content ratio of phenol of formula (1) is 95 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less, relative to 100 mol% of the total amount of phenols of formula (1) and formula (2) contained in the solution. From a similar viewpoint, it is preferable that the content ratio of phenol of formula (2) is more than 5 mol%, more preferably more than 10 mol%, and even more preferably more than 15 mol%, relative to 100 mol% of the total amount of phenols of formula (1) and formula (2).

[0021] Furthermore, in the manufacturing method according to this embodiment, from the viewpoint of polymerization reactivity, it is preferable that the content ratio of phenol of formula (1) is greater than 50 mol%, more preferably greater than 60 mol%, and even more preferably greater than 70 mol%, relative to a total of 100 mol% of phenols of formula (1) and formula (2) contained in the solution. From a similar viewpoint, it is preferable that the content ratio of phenol of formula (2) is 50 mol% or less, more preferably 40 mol% or less, and even more preferably 30 mol% or less, relative to a total of 100 mol% of phenols of formula (1) and formula (2).

[0022] Furthermore, since the phenol in formula (1) above 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 the phenol in formula (1) above contain repeating units having the structure of formula (4) below. [ka] (In formula (4), 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, the repeating units derived from the phenol of formula (2) have the structures of formulas (5) and (6) below, or combinations thereof. [ka] [ka] (R in equations (5) and (6)) 21 , R 22 This is the same as equation (2).

[0024] Furthermore, the raw materials may include phenol of the following formula (7). [ka] (In equation (7), X is a single bond or any a-valent linking group, a is an integer from 1 to 6, R 4 k is either a linear alkyl group having 1 to 8 carbon atoms or a substructure represented by formula (3) above, and k is an integer from 1 to 4, independently of the others.

[0025] In equation (7) above, R 4Each of these is independently one of a linear alkyl group having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, or an n-propyl group, and one of the substructures represented by formula (3) above, and it is preferable that they are a methyl group or the structure of formula (3) above. Each of the a substructures may be the same or different. In particular, from the viewpoint of obtaining a polyphenylene ether with even better solubility in the solvent and an even higher glass transition temperature after curing, it is preferable that each of the a substructures is the same.

[0026] In the above formula (7), k is an integer between 1 and 4, preferably between 2 and 4.

[0027] Also, in equation (7) above, R 4 At least one of the R atoms is bonded to at least one of the carbon atoms at positions 2 and 6, with the carbon atom of the benzene ring to which the -O- is bonded being at position 1, and R atoms bonded to positions 2 and / or 6. 3 When is a linear alkyl group having 1 to 8 carbon atoms, it is preferable that it is bonded to both the 2nd and 6th positions, and R bonded to the 2nd and / or 6th positions 4 If the substructure is represented by formula (3), it is preferable that it is bonded to only one of either the 2nd or 6th position.

[0028] The polyphenylene ether may also include repeating units derived from the phenol of formula (7), as well as repeating units derived from the phenol of formula (1) and repeating units derived from the phenol of formula (2). In this case, R in equation (2) above 21 and R in equation (7) above 4 However, if both are substructures (functional groups) represented by formula (3) (i.e., both the phenol compound of formula (2) and the phenol compound of formula (7) are substituted with the substructures (functional groups) represented by formula (3)), the structures of each substructure (functional group) represented by formula (3) may be the same or different.

[0029] Furthermore, in formula (7) above, X is any a-valent linking group or single bond, and is not particularly limited, but examples include hydrocarbon groups such as chain hydrocarbons and cyclic hydrocarbons; hydrocarbon groups containing one or more atoms selected from nitrogen, phosphorus, silicon, and oxygen; atoms such as nitrogen, phosphorus, and silicon; or groups combining these. X may be a linking group that links a substructures together.

[0030] As for X above, R is connected via a single bond or an ester bond, etc. 4 R 4 R 4 Examples include α-valent heterocyclic skeletons bonded to a benzene ring.

[0031] Here, the alkyl skeleton is not particularly limited, but examples include a chain hydrocarbon with 2 to 6 carbon atoms and at least a branched chain (e.g., a chain saturated hydrocarbon) in which the branched ends are directly bonded to the benzene ring of the substructure (it is sufficient that a benzene ring is bonded to a branched end, and there may be branched ends that are not bonded to a benzene ring). Also, the aryl skeleton is not particularly limited, but examples include a benzene ring, a mesitylene group, or a 2-hydroxy-5-methyl-1,3-phenylene group bonded via a single bond or an alkyl chain, R 4 Examples include skeletons that bond to a benzene ring to which R is attached. Furthermore, there are no particular limitations on the heterocyclic skeleton, but for example, a triazine ring is bonded via a single bond or alkyl chain, 4 Examples include skeletons that bond to the benzene ring to which the compound is attached.

[0032] In the above formula (7), a is an integer between 2 and 6, preferably between 2 and 4.

[0033] The polyphenylene ether thus obtained preferably has a molecular weight distribution (Mw / Mn) of 2.0 to 6.0, more preferably 2.5 to 5.5, and even more preferably 3.0 to 5.0, as determined by gel permeation chromatography (GPC). A molecular weight distribution (Mw / Mn) of 2.0 or higher, as determined by gel permeation chromatography (GPC), improves the fluidity of polyphenylene ether. A molecular weight distribution (Mw / Mn) of 6.0 or lower improves the toughness of polyphenylene ether and enhances its mechanical properties.

[0034] Means for adjusting the molecular weight distribution of the polyphenylene ether to the above range include adjusting the polymerization temperature, adjusting the catalyst equivalent, and adjusting the monomer concentration in the reaction system, from the viewpoint of controlling polymerization reactivity. Among these, a method of gradually adding monomers to the reaction system is preferred for adjusting the monomer concentration in the reaction system. If the monomer concentration in the reaction system is high from the beginning, it is difficult to control the molecular weight of the resulting polymer because the reaction rate between monomers is fast. On the other hand, by adding monomers to the reaction system at an appropriate flow rate, the monomer concentration in the reaction system can be controlled, and the reaction rate can be easily controlled. As a result, a polymer having a molecular weight distribution within a desirable range can be obtained.

[0035] Furthermore, the polyphenylene ether obtained in this embodiment has a reduced viscosity (ηsp / c) of 0.03 to 0.30 dL / g, preferably 0.05 to 0.28 dL / g, and more preferably 0.07 to 0.25 dL / g, measured in a chloroform solution with a concentration of 0.5 g / dL at 30°C. A reduced viscosity (ηsp / c) of 0.03 dL / g or higher, measured in a 0.5 g / dL chloroform solution at 30°C, indicates high heat resistance and excellent dielectric properties derived from the polyphenylene ether structure. A reduced viscosity (ηsp / c) of 0.30 dL / g or lower ensures solubility in solvents such as toluene and methyl ethyl ketone. The reduced viscosity can be measured by a known measurement method.

[0036] (Method for producing polyphenylene ether) The method for producing polyphenylene ether according to this embodiment is a method for producing polyphenylene ether in which the reduced viscosity (ηsp / c) measured with a chloroform solution of 0.5 g / dL concentration at 30°C is 0.03 to 0.30 dL / g, In a polymerization reactor, an oxidative polymerization step is performed by introducing an oxygen-containing gas into a solution containing phenol of formula (1) and phenol of formula (2) below and carrying out oxidative polymerization. The process includes a deactivation step of adding a deactivator to deactivate the entire amount of catalyst in the polymerization reactor.

[0037] The oxidative polymerization process consists of an early polymerization stage and a late polymerization stage. In this specification, "early polymerization stage" may also be referred to as the "early polymerization stage," and "late polymerization stage" as the "late polymerization stage." In this embodiment, the early polymerization stage refers to the period from the start of the oxidative polymerization process until the point in time when the height of the observed foam deposit layer reaches its maximum, and the late polymerization stage refers to the period from the point in time when the height of the observed foam deposit layer reaches its maximum until the end of the oxidative polymerization process.

[0038] In the polyphenylene ether production method of this embodiment, the increase or decrease in the height of the foam deposition layer is observed during the oxidative polymerization step. The method for observing the increase or decrease in the height of the foam deposition layer is not particularly limited, but it can be observed, for example, by visual inspection.

[0039] The timing for moving from the pre-polymerization stage to the post-polymerization stage is determined by visually checking the area occupied by the foaming portion (the area where foam in the polymerization solution is deposited) every minute during oxidative polymerization. The point at which the amount of foam accumulation does not change for three consecutive times, i.e., when the height (cm) of the foam accumulation layer reaches its maximum, is determined.

[0040] In the manufacturing process of polyphenylene ether, when a phenol having a hydrogen atom in the ortho position, such as the phenol in formula (2) above, is subjected to oxidative polymerization, a reaction occurs that generates the structure represented by formula (6) starting from the ortho position, resulting in the formation of a branched structure and improving the toughness of the polymer. Therefore, the film of the polymerization solution that forms the foam deposition layer, that is, the film of the polymer that holds the gas, is tough, the defoaming rate is slow, and the foam deposition layer accumulates. This tendency is greatly influenced by the oxidative polymerization activity, and the higher the activity, the more pronounced the formation of the foam deposition layer. In order to reduce polymer loss due to the foam deposition layer, it is necessary to control the oxidative polymerization activity to suppress the amount of foam deposition.

[0041] Therefore, in the polyphenylene ether production method of this embodiment, a deactivation step is performed so that the polymerization time in the later stages of polymerization accounts for 40-60% of the total polymerization time of the oxidative polymerization step. By setting the proportion of the later stages of polymerization to 40-60%, the reaction activity during polyphenylene ether production can be maintained while reducing the accumulation layer of bubbles generated during the reaction at an early stage, thereby reducing the amount of deposits on the inner wall of the reaction vessel. From a similar viewpoint, the polymerization time in the later stage of the polymerization process is preferably 45-58% of the total polymerization time of the oxidative polymerization process, more preferably 48-56%, and particularly preferably 50-55%.

[0042] Furthermore, the time from the point when the height of the foam deposit layer reaches its maximum to the point when the foam is reduced to 1 / 10 of that height is preferably 25% or less, more preferably 20% or less, and particularly preferably 15% or less, relative to the time in the later stages of polymerization.

[0043] Here, the deactivation step is the step of adding a deactivator that deactivates the entire amount of catalyst. "Deactivator that deactivates the entire amount of catalyst" means an amount of deactivator that is expected to substantially deactivate the entire amount of catalyst. The type of deactivator is not particularly limited, but examples include water, hydrochloric acid, acetic acid or other acids, or ethylenediaminetetraacetic acid (EDTA) and its salts, nitrilotriacetic acid and its salts, etc. Furthermore, the timing for adding the deactivator (performing the deactivation step) is when the polymerization time in the later stages of polymerization accounts for 40-60% of the total polymerization time of the oxidative polymerization step, and can be appropriately adjusted depending on the expected polymerization time in the later stages of polymerization. In this embodiment, the end point of the oxidative polymerization step is just before adding the deactivator, and the oxidative polymerization step and the deactivation step do not overlap.

[0044] Examples of the phenol compound of formula (1) contained in the solution 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 phenol compound of formula (1) above may be used individually or in combination of multiple types.

[0045] Examples of the phenol compound of formula (2) contained in the solution 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, 2-t-butyl-5-methylphenol and 2-cyclohexyl-5-methylphenol, which have bulky substituents, are more preferred. The phenol compound of formula (2) above may be used individually or in combination of multiple types.

[0046] Examples of the phenol compound of formula (7) contained in the solution include phenol compounds having two phenol units in the molecule or phenol compounds having three phenol units in the molecule. Among the phenol compounds of formula (7) above, examples of phenol compounds having two phenol units in the molecule include 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,4'-methylenebis(2,6-dimethylphenol), bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxy-3,5-dimethylphenyl)sulfone, α,α'-bis(4-hydroxy-3,5-dimethylphenyl)-1,4-diisopropylbenzene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, and 1,1-bis(2-methyl-4-hydroxy-5-t-butylphenyl)butane. In particular, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane and 1,1-bis(2-methyl-4-hydroxy-5-t-butylphenyl)butane are preferred because they are inexpensive and readily available.

[0047] Furthermore, among the phenol compounds of formula (7) above, phenol compounds having three or more phenol units in the molecule include, for example, 4,4'-[(3-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(3-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), and 4,4'-[(2-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol). [xy-3-methoxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(4-hydroxy-3-ethoxyphenyl)methylene]bis(2,3,6-trimethylethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 2,2'-[(4-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol), 4,4'-[4-(4-hydroxyphenyl [(2-hydroxyphenyl)methylene]-bis(2,6-dimethylphenol), 4,4'-[(2-hydroxyphenyl)methylene]-bis(2,3,6-trimethylphenol), 4,4'-[1-[4-[1-(4-hydroxy-3,5-dimethylphenyl)-1-methylethyl]phenyl]ethylidene]bis(2,6-dimethylphenol), 4,4'-[1-[4-[1-(4-hydroxy-3-fluorophenyl)-1-methylethyl]phenyl]ethylidene]bis(2,6-dimethylphenol), 2,6-bis[(4-hydroxy-3,5-dimethyl Phenyl)ethyl]-4-methylphenol, 2,6-bis[(4-hydroxy-2,3,6-trimethylphenyl)methyl]-4-methylphenol, 2,6-bis[(4-hydroxy-3,5,6-trimethylphenyl)methyl]-4-ethylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-methylphenol, 2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-methylphenol, 2,4-bis[(4-hydroxy-3-cyclohexylphenyl)methyl]-6-methylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-cyclohexylphenol, 2,4-bis[(2-hydroxy-5-methylphenyl)methyl]-6-cyclohexylphenol, 2,4-bis[(4-hydroxy-2,3,6-trimethylphenyl)methyl]-6-cyclohexylphenol, 3,6-bis[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,2-benzenediol, 4,6-bis[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,4,6 -Tris[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,4,6-Tris[(2-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,2'-Methylenebis[6-[(4 / 2-hydroxy-2,5 / 3,6-dimethylphenyl)methyl]-4-methylphenol], 2,2'-Methylenebis[6-[(4-hydroxy-3,5-dimethylphenyl)methyl]-4-methylphenol], 2,2'-Methylenebis[6-[(4 / 2-hydroxy-2,3,5 / 3 [4,6-trimethylphenyl)methyl]-4-methylphenol], 2,2'-methylenebis[6-[(4-hydroxy-2,3,5-trimethylphenyl)methyl]-4-methylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxyphenyl)methyl]-6-methylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxyphenyl)methyl]-3,6-dimethylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxy-3-methylphenyl)methyl]-3,6-dimethylphenol 4,4'-methylenebis[2-[(2,3,4-trihydroxyphenyl)methyl]-3,6-dimethylphenol], 6,6'-methylenebis[4-[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,2,3-benzenetriol], 4,4'-cyclohexyllidenbis[2-cyclohexyl-6-[(2-hydroxy-5-methylphenyl)methyl]phenol], 4,4'-cyclohexyllidenbis[2-cyclohexyl-6-[(4-hydroxy-3,5-dimethylphenyl)methyl]phenol], 4,Examples include 4'-cyclohexyllidenebis[2-cyclohexyl-6-[(4-hydroxy-2-methyl-5-cyclohexylphenyl)methyl]phenol], 4,4'-cyclohexyllidenebis[2-cyclohexyl-6-[(2,3,4-trihydroxyphenyl)methyl]phenol], 4,4',4'',4'''-(1,2-ethanediylidene)tetrakis(2,6-dimethylphenol), 4,4',4'',4'''-(1,4-phenylenedimethylidene)tetrakis(2,6-dimethylphenol), and 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane. Among these, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane is particularly preferred due to its low cost and easy availability. The phenol compound of formula (7) above may be used individually or in combination of multiple types.

[0048] The number of phenolic hydroxyl groups in the phenol compound of formula (7) above is not particularly limited as long as it is between 2 and 6, but it is preferably between 2 and 4 from the viewpoint of making it easier to control the thermosetting rate.

[0049] Typically, oxidative polymerization of phenols with a hydrogen atom in the ortho position (e.g., 2-methylphenol, 2,5-dimethylphenol, 2-phenylphenol) can form ether bonds 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 with an average of 3.5 or more hydroxyl groups per molecule, which are polymerized in a branched manner, ultimately generating a gel component that is insoluble in the solvent.

[0050] On the other hand, if the phenol in formula (2) has a bulky substituent at one ortho position, it becomes possible to control the bonding position of the phenol compound during oxidative polymerization, even though there is a hydrogen atom at the opposite ortho position, and it is possible to obtain a polyphenylene ether with an average of less than 3.0 hydroxyl groups per molecule.

[0051] Furthermore, if the phenol in formula (2) has a bulky substituent at one of its ortho positions, even if a monovalent phenol having a non-bulky substituent (e.g., hydrogen atom, allyl group, methyl group, ethyl group, methoxy group, etc.) at the ortho position of the oxygen atom of the phenol is used as the third component, gelation does not occur, and a polyphenylene ether with an average of less than 3.0 hydroxyl groups per molecule can be obtained.

[0052] Furthermore, the molecular weight of the polyphenylene ether can be adjusted, for example, by the molar ratio of the structure of formula (2) to the total of the structures of formula (1) and formula (2), or by the molar ratio of the structure of formula (7) to the total of the structures of formula (1) and formula (7). In other words, if the molar ratio of the structure of formula (2) or formula (7) is high, the molecular weight (reduced viscosity) can be lowered, and if the molar ratio of the structure of formula (2) or formula (7) is low, the molecular weight (reduced viscosity) can be adjusted to be higher.

[0053] In the method for producing polyphenylene ether, an aromatic solvent, which is a good solvent for polyphenylene ether, can be used as the polymerization solvent in the oxidative polymerization step.

[0054] A good solvent for polyphenylene ether is a solvent that can dissolve polyphenylene ether. Examples of such solvents include aromatic hydrocarbons such as benzene, toluene, xylene (including o-, m-, and p- isomers), and ethylbenzene, as well as halogenated hydrocarbons such as chlorobenzene and dichlorobenzene; nitro compounds such as nitrobenzene; and the like.

[0055] As polymerization catalysts, generally known catalyst systems that can be used for the production of polyphenylene ethers can be used. Commonly known catalyst systems consist of a transition metal ion with redox potential 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 manganese compound and an amine compound, a cobalt compound and an amine compound, etc. Since the polymerization reaction proceeds efficiently under slightly alkaline conditions, a small amount of alkali or further amine compounds may be added.

[0056] Furthermore, preferred polymerization catalysts include catalysts comprising a copper compound, a halogen compound, and an amine compound as catalyst components, and more preferably catalysts containing a diamine compound represented by the following formula (10) as the amine compound. [ka] (In formula (10), R 14 , R 15 , R 16 , R 17 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. 18 (This refers to an alkylene group having 2 to 5 carbon atoms, either linear or methyl-branched.)

[0057] 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).

[0058] Examples of the 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 also be used as aqueous solutions or 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.

[0059] 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.

[0060] Examples of the diamine compounds of the catalyst component include 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 Examples include -butylethylenediamine, 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 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.

[0061] Furthermore, the polymerization catalyst may contain primary amines and secondary monoamines as constituent components. Examples of secondary monoamines, but not limited to those listed below, 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.

[0062] The polymerization catalyst may also contain 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. 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.

[0063] In this embodiment, there are no restrictions 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 Aliquat336 and Capriquat.

[0064] Conditions for oxygen-containing gases In the polyphenylene ether production method of this embodiment, oxidative polymerization is initiated by introducing an oxygen-containing gas into a reaction solution containing the raw material phenol, polymerization catalyst, and solvent in the polymerization reactor. As the oxygen-containing gas used in the polymerization, 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 can be used. While atmospheric pressure is sufficient for the system pressure during the polymerization reaction, it can be reduced or increased as needed.

[0065] The oxygen concentration of the oxygen-containing gas is not particularly limited, but it is preferably 5 to 25% by volume relative to 100% by volume of the oxygen-containing gas. In particular, when it contains nitrogen-containing gas and air, the oxygen concentration is more preferably 6 to 20% by volume, and even more preferably 8 to 12% by volume. Such a favorable oxygen concentration tends to lead to more stable heat removal and polymerization rates.

[0066] In the manufacturing method of this embodiment, the amount of oxygen-containing gas to be permeated during the pre-polymerization stage is preferably 10 to 20 L / min per 1 kg of phenolic compound subjected to the polymerization reaction. More preferably, the lower limit can be 11 L / min, 12 L / min, 13 L / min, 14 L / min, 15 L / min, 16 L / min, or 17 L / min, and the upper limit can be 19 L / min or 18 L / min. By setting the aeration rate of the oxygen-containing gas during the initial polymerization stage to 10 L / min or more, the target polyphenylene ether tends to reach the desired reduced viscosity earlier, leading to improved productivity. On the other hand, setting it to 20 L / min or less tends to avoid problems such as excessive equipment size and increased exhaust gas volume, resulting in better economic performance.

[0067] Furthermore, when changing the amount of air permeation during the oxidative polymerization, it is preferable to make the amount of oxygen-containing gas permeation in the later stages of polymerization less than the amount of oxygen-containing gas permeation in the earlier stages of polymerization. Specifically, the amount of oxygen-containing gas to be permeated during the later stages of polymerization is preferably 0.5 to 9.9 L / min, more preferably 1.0 to 5.0 L / min, and even more preferably 1.0 to 2.0 L / min per 1 kg of phenolic compound subjected to the polymerization reaction. By setting the aeration rate of the oxygen-containing gas during the later stages of polymerization to 0.5 L / min or more, the target polyphenylene ether tends to reach the desired reduced viscosity earlier, leading to improved productivity. On the other hand, by setting the aeration rate of the oxygen-containing gas during the later stages of polymerization to 9.9 L / min or less, problems such as an increase in the foam accumulation layer and an increase in foaming time can be avoided, and adhesion to the inner wall of the reaction vessel tends to decrease.

[0068] Furthermore, in the oxidative polymerization step, the polymerization reaction activity of polyphenylene ether can be controlled within an appropriate range by adjusting the amount of oxygen-containing gas supplied to the reaction vessel, thereby suppressing the amount of foam buildup generated during the production process of polyphenylene ether.

[0069] In the method for producing polyphenylene ether according to this embodiment, an oxidative polymerization step is carried out using the phenol of formula (1) and the phenol of formula (2) above, and the polarity state of the reaction solution containing the raw materials, solvent, and catalyst differs from that of general oxidative polymerization using 2,6-dimethylphenol. It is presumed that the above-mentioned effect is achieved because the size of the bubbles and the layer of bubble deposition caused by the supply of oxygen-containing gas can be appropriately controlled by managing the amount of oxygen-containing gas used in polymerization.

[0070] Conditions for polymerization solution The polymerization solution for the oxidative polymerization reaction (a solution containing phenol of formula (1) and phenol of formula (2)) may be prepared by introducing the components of the phenolic compound, aromatic solvent, and catalyst into the reactor individually, or by pre-dissolving the phenolic compound and catalyst in the aromatic solvent before introducing them into the reactor. However, it is preferable to first introduce the catalyst, which has been pre-dissolved in a portion of the aromatic solvent, into the reactor, and then introduce the phenolic compound, which has been dissolved in the remaining aromatic solvent, into the reactor.

[0071] Furthermore, the concentration of the phenolic compound in the polymerization solution during the initial stage of polymerization is not particularly limited as long as the desired effects in this embodiment are ensured. However, from the viewpoint of improving polymerization activity and considering the productivity of polyphenylene ether, it is preferably 15 to 25% by mass or less, more preferably 15 to 22% by mass or less, and even more preferably 15 to 20% by mass or less. By adopting the above preferred embodiment, the polymerization reaction of polyphenylene ether tends to be stably controlled.

[0072] In the method for producing polyphenylene ether according to this embodiment, all or part of the remaining aromatic solvent, after excluding a portion of the aromatic solvent used in the polymerization solution during the first stage of polymerization, can be added to the polymerization solution during the second (later) stage of the oxidative polymerization reaction. In this embodiment, by adding the aromatic solvent in two separate stages, the initial foaming of the polymerization solution can be suppressed while simultaneously preventing adhesion to the inner wall of the reaction vessel. The reaction time (polymerization time) can be measured by the method described in the examples below.

[0073] In the method for producing polyphenylene ether according to this embodiment, the formation of a foam deposit layer that occurs in the later stages of polymerization can be suppressed, which allows for an increase in the amount charged into the reactor and tends to improve production efficiency.

[0074] Furthermore, the method of adding the aromatic solvent is not particularly limited, as long as the aromatic solvent can be added to the polymerization solution in the early stages of polymerization. It may be added from the top of the reactor or from the circulation line of the reactor.

[0075] The polymerization solution obtained by adding the solvent as described above can be used as is for the later stages of polymerization, and the oxidative polymerization in the early stages of polymerization can be continued in the later stages of polymerization as well.

[0076] In this embodiment, from the viewpoint of the productivity of polyphenylene ether and the foam deposition layer, the concentration of the phenolic compound in the polymerization solution in the later stages of polymerization is preferably 5% by mass or more and less than 15% by mass, more preferably 7 to 13% by mass, and even more preferably 9 to 12% by mass.

[0077] In this embodiment of the method for producing polyphenylene ether, an oxidative polymerization step is carried out using the phenol of formula (1) and the phenol of formula (2) described above. The polarity of the reaction solution, including the raw materials, solvent, and catalyst, differs from that of general oxidative polymerization using 2,6-dimethylphenol. It is presumed that the above-mentioned effect is achieved because the size of bubbles and the layer of bubble deposition can be appropriately controlled by changing the viscosity of the reaction solution through controlling the concentration of the phenolic compound used in polymerization.

[0078] • Stirring speed of the agitator In the method for producing polyphenylene ether according to this embodiment, it is preferable to appropriately adjust the rotational speed (stirring speed of the stirrer) of the stirrer installed in the reaction vessel for the oxidative polymerization of polyphenylene ether during the early and late stages of polymerization, from the viewpoint of reaction progress and catalyst activity. For example, it is preferable to adjust the stirring speed during the early stage of polymerization to 500 to 1000 rpm, more preferably to 550 to 900 rpm, and even more preferably to 600 to 800 rpm.

[0079] Furthermore, in the later stages of polymerization, it is preferable to set the stirring speed of the stirrer to 60% or less of the stirring speed in the earlier stages of polymerization, more preferably to 55% or less, and even more preferably to 50% or less. This is because it is possible to reduce the foam accumulation layer. On the other hand, in the later stages of polymerization, it is preferable to set the stirring speed of the stirrer to 30% or more of the stirring speed in the earlier stages of polymerization, more preferably to 35% or more, and even more preferably to 40% or more. This is because it is possible to maintain good progress of the polymerization reaction. Therefore, the rotation speed of the stirrer during the later stages of polymerization is preferably 200 to 480 rpm, more preferably 230 to 450 rpm, and even more preferably 250 to 400 rpm. This reduces the foam accumulation layer without hindering the progress of the polymerization reaction.

[0080] In this embodiment of the method for producing polyphenylene ether, an oxidative polymerization step is carried out using the phenol of formula (1) and the phenol of formula (2) above, and the polarity state of the reaction solution, including the raw materials, solvent, and catalyst, differs from that of general oxidative polymerization using 2,6-dimethylphenol. It is presumed that the above-mentioned effects are achieved because the size of bubbles and the accumulation layer of bubbles can be appropriately controlled by optimizing the size of the oxygen-containing gas in the reaction solution through the stirring speed of the reaction vessel used for polymerization.

[0081] • Temperature inside the reaction vessel In the method for producing polyphenylene ether according to this embodiment, in the early stage of polymerization in the oxidative polymerization step, the temperature of the polymerization solution containing polyphenylene ether is preferably adjusted to 0 to 80°C, more preferably to 10 to 60°C, and even more preferably to 20 to 50°C, from the viewpoint of reaction progress and catalyst activity. Furthermore, it is preferable to adjust the temperature of the polymerization solution in the later stages of the oxidative polymerization process to less than 90% of the temperature in the earlier stages of polymerization. Therefore, the temperature of the polymerization solution in the later stages is preferably 0 to 70°C, more preferably 10 to 50°C, and even more preferably 15 to 35°C. This tends to reduce the accumulation of foam without hindering the progress of the polymerization reaction.

[0082] In this embodiment of the method for producing polyphenylene ether, an oxidative polymerization step is carried out using the phenol of formula (1) and the phenol of formula (2) described above, and the polarity state of the reaction solution, including the raw materials, solvent, and catalyst, differs from that of general oxidative polymerization using 2,6-dimethylphenol. It is presumed that the above-mentioned effect is achieved because the size of bubbles and the accumulation layer of the bubbles can be appropriately controlled by controlling the temperature of the reaction solution used for polymerization, thereby suppressing the oxygen absorption efficiency.

[0083] • Conditions for adding water In the method for producing polyphenylene ether according to this embodiment, water may be added to the polymerization solution during the later stages of the oxidative polymerization step. Specifically, it is preferable to prepare the solution with a blending ratio of 1 to 10 parts by mass, more preferably 2 to 8 parts by mass, even more preferably 2 to 6 parts by mass, and most preferably 2 to 4 parts by mass, based on 100 parts by mass of the total amount of the phenolic compound, aromatic solvent, and catalyst in the polymerization solution. This tends to suppress the accumulation of the foam layer without hindering the progress of the polymerization reaction.

[0084] In this embodiment of the method for producing polyphenylene ether, an oxidative polymerization step is carried out using the phenol of formula (1) and the phenol of formula (2) described above, and the polarity state of the reaction solution, including the raw materials, solvent, and catalyst, differs from that of general oxidative polymerization using 2,6-dimethylphenol. It is presumed that the above-mentioned effects are achieved because the amount of water in the reaction solution used for polymerization can be controlled to optimize the oxygen absorption efficiency and the size of the oxygen-containing gas in the reaction solution, thereby appropriately controlling the size of the bubbles and the bubble deposition layer.

[0085] The method for adding water to the polymerization solution is not particularly limited, as long as water can be added to the reactor in the later stages of polymerization. It may be added from the top of the reactor or from the reactor's circulation line.

[0086] Conditions for adding polyphenylene ether In the method for producing polyphenylene ether according to this embodiment, polyphenylene ether obtained using a solution containing the phenol of formula (1) and the phenol of formula (2), preferably further containing the phenol of formula (7), may be added. Specifically, it is preferable to carry out an oxidative polymerization step and a post-treatment step after the polymerization reaction is completed, and then add the polyphenylene ether obtained by this step to the polymerization solution of the phenolic compound, aromatic solvent, and catalyst to prepare the solution.

[0087] The amount of polyphenylene ether added is preferably adjusted to a ratio of 50 to 100 parts by mass per 100 parts by mass of the phenolic compound in the polymerization solution. This makes it possible to obtain the desired reduced viscosity (ηsp / c) without reducing productivity.

[0088] Furthermore, in the method for producing polyphenylene ether according to this embodiment, polymerization can also be carried out in a poor solvent such as an alcohol.

[0089] Furthermore, in the method for producing polyphenylene ether according to 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, 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 also 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.

[0090] In the method for producing polyphenylene ether according to this embodiment, water may be added to extract the compound from which the copper catalyst has been deactivated, and after liquid-liquid separation into an organic phase and an aqueous phase, the copper catalyst may 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.

[0091] 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.

[0092] The method for volatilizing the solvent contained in the organic phase is not particularly limited, but examples include transferring the organic phase to a high-temperature concentration tank and concentrating it by distilling off the solvent, or concentrating it by distilling off toluene using equipment such as a rotary evaporator.

[0093] 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.

[0094] To obtain the aforementioned polyphenylene ether with high efficiency, 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 preferred 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. [Examples]

[0095] The embodiment will be described in more detail below based on the following examples, but this embodiment is not limited to the following examples.

[0096] <Production of polyphenylene ether> • Example 1 A 40-liter jacketed polymerization reactor is equipped with a 50mm diameter spagger at the bottom of the reactor for introducing oxygen-containing gas, with a mesh filter (made of stainless steel, 150 mesh) with a mesh opening of 0.11mm at the tip. It also has stirring turbine blades and baffles, and a reflux condenser in the vent gas line at the top of the polymerization reactor. Nitrogen gas is blown into the reactor at a flow rate of 73.1 L / min while adding 3.7 g of cupric oxide, 28.1 g of 47% by mass aqueous solution of hydrogen bromide, 9.0 g of di-tert-butylethylenediamine, 43.5 g of di-n-butylamine, 132.6 g of butyldimethylamine, 13.8 kg of toluene, and 2.0 g of trioctylmethylammonium chloride (R=C8- 10 Add the following ingredients and adjust the stirrer to 600 rpm to create a homogeneous solution. (Early polymerization stage) Subsequently, using a pump, 754.6 g of 2-tert-butyl-5-methylphenol, 2245.4 g of 2,6-dimethylphenol, and 3.0 kg of toluene were added dropwise to the polymerization reactor over 35 minutes. Simultaneously, air was introduced into the polymerization solution from the bottom of the reactor at a rate of 45.0 L / min via a sparger, and polymerization was initiated. The area occupied by the foaming portion (the foaming portion of the polymerization solution) was visually checked every minute. After confirming that the amount of foam accumulation remained unchanged for three consecutive times, i.e., that the height (cm) of the foam accumulation layer had reached its maximum, the process immediately proceeded to the later stages of polymerization. (Late stage of polymerization) Then, after moving to the later stages of polymerization, the air flow rate was changed to 4.5 L / min, and the nitrogen gas flow rate was also changed to 7.3 L / min. Air and nitrogen gas were passed through until the polymerization was complete to obtain the polymerization mixture. During polymerization, the internal temperature was controlled to 40°C. At the end of polymerization, the polymerization mixture (polymerization solution) was in a homogeneous solution state. (Inactivation process, post-treatment) 279 minutes after the start of oxidative polymerization, the polymerization was stopped by adding 0.60 kg of a 10% aqueous solution of tetrasodium ethylenediaminetetraacetate (manufactured by Dojin Chemical Laboratories) as a deactivator, and the polymerization solution was stirred at 75°C for 150 minutes. The polymerization solution was then withdrawn from the reactor and introduced into a liquid-liquid separator. The solution was then allowed to stand for 60 minutes, and the organic phase and aqueous phase were separated by liquid-liquid separation. The obtained organic phase was precipitated and washed with 22.5 kg of methanol, then filtered to obtain a wet polyphenylene ether. The obtained wet polyphenylene ether was dried at a temperature of 130°C for 180 minutes to obtain the polyphenylene ether of Example 1.

[0097] • Example 2 The procedure was carried out in the same manner as in Example 1, except that 10.0 kg of toluene was added dropwise to the polymerization reactor over 7 minutes using a pump 140 minutes after air was introduced, the flow rates of air and nitrogen were kept constant, and the oxidative polymerization was stopped 270 minutes after the start of oxidative polymerization, to obtain polyphenylene ether.

[0098] • Example 3 The procedure was carried out in the same manner as in Example 1, except that the stirrer speed was changed to 250 rpm 142 minutes after air was introduced, the flow rates of air and nitrogen were kept constant, and the oxidative polymerization was stopped 274 minutes after the start of oxidative polymerization, to obtain polyphenylene ether.

[0099] • Example 4 Using a pump, 389.9 g of 2-tert-butyl-5-methylphenol, 2610.1 g of 2,6-dimethylphenol, and 3.0 kg of toluene were added dropwise to the polymerization reactor over 35 minutes. After 126 minutes of aeration with air, the stirrer speed was changed to 350 rpm, the flow rates of air and nitrogen were kept constant, and the oxidative polymerization was stopped 257 minutes after the start of oxidative polymerization. The procedure was carried out in the same manner as in Example 1, except that the procedure was carried out in the same manner as in Example 1.

[0100] • Example 5 The procedure was carried out in the same manner as in Example 1, except that the temperature inside the polymerization reactor was controlled to 20°C 140 minutes after air was introduced, the flow rates of air and nitrogen were kept constant, and the oxidative polymerization was stopped 272 minutes after the start of oxidative polymerization, to obtain polyphenylene ether.

[0101] • Example 6 Using a pump, a dropwise solution of 1096.6 g of 2-tert-butyl-5-methylphenol, 1903.4 g of 2,6-dimethylphenol, and 3.0 kg of toluene was added dropwise to the polymerization reactor over 35 minutes. After 168 minutes of venting with air, the temperature inside the polymerization reactor was controlled to 30°C, the flow rates of air and nitrogen were kept constant, and the oxidative polymerization was stopped 376 minutes after the start of oxidative polymerization. The procedure was carried out in the same manner as in Example 1 to obtain polyphenylene ether.

[0102] • Example 7 The procedure was carried out in the same manner as in Example 1, except that 142 minutes after air was introduced, 1.0 part by mass of water was added to the polymerization reactor dropwise over 0.5 minutes using a pump, the flow rates of air and nitrogen were kept constant, and the oxidative polymerization was stopped 288 minutes after the start of oxidative polymerization. A polyphenylene ether was obtained.

[0103] • Example 8 Except that 140 minutes after air was introduced, 4.0 parts by mass of water were added to the polymerization reactor dropwise over 2 minutes using a pump, the flow rates of air and nitrogen were kept constant, and the oxidative polymerization was stopped 306 minutes after the start of oxidative polymerization, the same procedure as in Example 1 was followed to obtain polyphenylene ether.

[0104] • Example 9 The procedure was carried out in the same manner as in Example 4, except that 128 minutes after air was introduced, 4.0 parts by mass of water were added to the polymerization reactor dropwise over 2 minutes using a pump, the stirrer speed was kept constant, and the oxidative polymerization was stopped 269 minutes after the start of oxidative polymerization, to obtain polyphenylene ether.

[0105] • Example 10 Except for adding 5.0 parts by mass of water to the polymerization reactor over 2.5 minutes using a pump 166 minutes after air was introduced to maintain a constant temperature in the polymerization reactor, and stopping the oxidative polymerization 407 minutes after the start of the oxidative polymerization, the procedure was carried out in the same manner as in Example 6 to obtain polyphenylene ether.

[0106] • Example 11 A 40-liter jacketed polymerization reactor is equipped with a 30mm diameter spurger at the bottom of the reactor for introducing oxygen-containing gas, with a mesh filter (made of stainless steel, 150 mesh) with a mesh opening of 0.11mm at the tip. It also has stirring turbine blades and baffles, and a reflux condenser in the vent gas line at the top of the polymerization reactor. Nitrogen gas is blown into the reactor at a flow rate of 73.1 L / min while adding 3.5 g of cupric oxide, 26.6 g of 47% by mass aqueous solution of hydrogen bromide, 8.5 g of di-tert-butylethylenediamine, 41.2 g of di-n-butylamine, 125.4 g of butyldimethylamine, 722.5 g of 2-tert-butyl-5-methylphenol, 2149.8 g of 2,6-dimethylphenol, 127.7 g of 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 16.8 kg of toluene, and 2.0 g of trioctylmethylammonium chloride (R=C8- 10 The procedure was carried out in the same manner as in Example 1, except that ) was added to make a homogeneous solution, air was passed through it, and after 145 minutes, 4.0 parts by mass of water were added to the polymerization reactor over 2 minutes using a pump, and the oxidative polymerization was stopped 313 minutes after the start of oxidative polymerization, in order to obtain polyphenylene ether. • Example 12 Polyphenylene ether was obtained by following the same procedure as in Example 11, except that 677.0 g of 2-tert-butyl-5-methylphenol, 2014.5 g of 2,6-dimethylphenol, and 308.5 g of 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane were used as the starting phenols, and 4.0 parts by mass of water were added dropwise to the polymerization reactor over 2 minutes using a pump 155 minutes after the air was introduced, and the oxidative polymerization was stopped 332 minutes after the start of oxidative polymerization.

[0107] • Example 13 A 40-liter jacketed polymerization reactor is equipped with a 50mm diameter spagger at the bottom of the reactor for introducing oxygen-containing gas, with a mesh filter (made of stainless steel, 150 mesh) with a mesh opening of 0.11mm at the tip. It also has stirring turbine blades and baffles, and a reflux condenser in the vent gas line at the top of the polymerization reactor. Nitrogen gas is blown into the reactor at a flow rate of 33.1 L / min while adding 2.0 g of cupric oxide, 14.0 g of 47% by mass aqueous solution of hydrogen bromide, 5.0 g of di-tert-butylethylenediamine, 21.8 g of di-n-butylamine, 66.3 g of butyldimethylamine, 13.9 kg of toluene, and 2.0 g of trioctylmethylammonium chloride (R=C8- 10 ) and 1500 g of polyphenylene ether obtained according to the post-treatment method after the polymerization reaction was completed were added to the polymerization solution obtained in Example 1, and the stirrer was adjusted to 600 rpm to make a homogeneous solution. (Early polymerization stage) Subsequently, using a pump, 377.3 g of 2-tert-butyl-5-methylphenol, 1122.7 g of 2,6-dimethylphenol, and 3.0 kg of toluene were added dropwise to the polymerization reactor over 30 minutes. Simultaneously, air was introduced into the polymerization solution from the bottom of the reactor at a rate of 22.5 L / min via a sparger, and polymerization was initiated. The area occupied by the foaming portion (the foaming portion of the polymerization solution) was visually checked every minute. After confirming that the amount of foam accumulation remained unchanged for three consecutive times, i.e., that the height (cm) of the foam accumulation layer had reached its maximum, the process immediately proceeded to the later stages of polymerization. (Late stage of polymerization) Then, after moving to the later stages of polymerization, the air flow rate was changed to 2.3 L / min, and the nitrogen gas flow rate was also changed to 3.3 L / min. Air and nitrogen gas were passed through until the polymerization was complete to obtain the polymerization mixture. During polymerization, the internal temperature was controlled to 40°C. At the end of polymerization, the polymerization mixture (polymerization solution) was in a homogeneous solution state. (Inactivation process, post-treatment) 283 minutes after the start of oxidative polymerization, the polymerization was stopped by adding 0.40 kg of a 10% aqueous solution of tetrasodium ethylenediaminetetraacetate (manufactured by Dojin Chemical Laboratories) as a deactivator, and the polymerization solution was stirred at 75°C for 150 minutes. The polymerization solution was then withdrawn from the reactor and introduced into a liquid-liquid separator. The solution was then allowed to stand for 60 minutes, and the organic phase and aqueous phase were separated by liquid-liquid separation. The obtained organic phase was precipitated and washed with 22.5 kg of methanol, then filtered to obtain a wet polyphenylene ether. The obtained wet polyphenylene ether was dried at a temperature of 130°C for 180 minutes to obtain the polyphenylene ether of Example 13.

[0108] • Example 14 The procedure was carried out in the same manner as in Example 12, except that 149 minutes after air was introduced, 3.0 parts by mass of water were added to the polymerization reactor dropwise over 1.5 minutes using a pump, the air flow rate was changed to 4.5 L / min at the same time, and the nitrogen gas flow rate was changed to 7.3 L / min. The oxidative polymerization was stopped 249 minutes after the start of the oxidative polymerization.

[0109] • Comparative Example 1 Except for keeping the flow rates of air and nitrogen constant, the procedure was carried out in the same manner as in Example 1 to obtain polyphenylene ether.

[0110] • Comparative Example 2 Except for keeping the stirrer speed constant, the procedure was carried out in the same manner as in Example 4 to obtain polyphenylene ether.

[0111] • Comparative Example 3 Except for keeping the temperature inside the polymerization reactor constant, the procedure was carried out in the same manner as in Example 6 to obtain polyphenylene ether.

[0112] • Comparative Example 4 The procedure was carried out in the same manner as in Example 11, except that water was not added dropwise to the polymerization reactor, to obtain polyphenylene ether.

[0113] • Comparative Example 5 The procedure was carried out in the same manner as in Example 12, except that water was not added dropwise to the polymerization reactor, to obtain polyphenylene ether.

[0114] ·Reference example 1 The procedure was carried out in the same manner as in Comparative Example 3, except that a dropwise solution of 3.0 kg of 2,6-dimethylphenol and 3.0 kg of toluene was added to the polymerization reactor over 35 minutes using a pump, to obtain polyphenylene ether.

[0115] <Conditions for the oxidative polymerization process and evaluation of the obtained polyphenylene ether> The conditions for the oxidative polymerization process and the evaluation of the obtained polyphenylene ether were measured and calculated as follows. The results are shown in Table 1.

[0116] (1) The point in time (minutes) when the amount of foam accumulation is at its maximum. The area occupied by the foaming portion (the foaming part of the polymerization solution) was visually checked every minute through a glass window on the side of the polymerization reaction vessel, and the point at which the amount of foam accumulation did not change for three consecutive times was defined as the maximum foaming polymerization time.

[0117] (2) Late polymerization ratio (%) The ratio of the late-stage polymerization process to the total polymerization time in the oxidative polymerization process (late-stage polymerization ratio) was calculated using the following formula. Polymerization late-stage ratio (%) = (Total polymerization time - Maximum foaming polymerization time) / Total polymerization time × 100

[0118] (3) Maximum foam accumulation (%) The height of the reaction solution (cm) and the height of the foam deposit layer (cm) were measured through a glass window on the side of the polymerization reactor. The height of the foam deposit layer relative to the sum of the heights of the reaction solution and the foam deposit layer was calculated using the following formula (1). The calculation results are shown in Table 1. Maximum foam accumulation (%) = Height of foam accumulation layer / (Height of reaction solution + Height of foam accumulation layer) × 100 ... Equation (1)

[0119] (4) Defoaming time (minutes) The time from when the foam deposit layer reached its maximum height (cm) to when it subsided to 1 / 10th of that height (cm) was measured and defined as the defoaming time (minutes).

[0120] (5) Measurement of reduced viscosity (ηsp / c) A 0.5 g / dL chloroform solution of the obtained polyphenylene ether was prepared, and its reduced viscosity (ηsp / c) (dL / g) at 30°C was determined using an Ubbelohde viscous tube.

[0121] (6) Yield (%) The yield of the obtained polyphenylene ether was calculated using the following formula (2). The calculation results are shown in Table 1. Yield (%) = obtained polyphenylene ether (g) / phenolic compound charged (g) × 100 ... Formula (2)

[0122] (7) Percentage of foam deposition time in the later stages of polymerization (%) The ratio of foaming time to polymerization time in the later stages of polymerization (foaming time ratio in the later stages of polymerization) was calculated using the following formula. Foaming time in the later stages of polymerization (%) = (Time when the foam layer height is reduced to 1 / 10 of its original height - Maximum foaming polymerization time) / (Total polymerization time - Maximum foaming polymerization time) × 100 [Table 1]

[0123] As shown in Table 1, the polyphenylene ethers produced in each example showed suppressed foam accumulation during the oxidative polymerization process, and the target reduced viscosity (ηsp / c) was achieved while maintaining polymerization activity. [Industrial applicability]

[0124] The resin composition containing polyphenylene ether of the present invention has industrial value as a method for producing polyphenylene ether because it can be manufactured in high yield despite having high oxidative polymerization activity.

Claims

1. A method for producing polyphenylene ether having a reduced viscosity (ηsp / c) of 0.03 to 0.30 dL / g as measured with a chloroform solution of 0.5 g / dL concentration at 30°C, An oxidative polymerization step is performed in a polymerization reactor by introducing an oxygen-containing gas into a solution containing phenol of formula (1) and phenol of formula (2) below, The process includes a deactivation step of adding a deactivator to deactivate the entire amount of catalyst in the polymerization reactor, In the aforementioned oxidation polymerization process, the increase or decrease in the height of the foam deposition layer during oxidation polymerization is observed. The aforementioned oxidation polymerization process consists of an early polymerization phase from the start of oxidation polymerization until the amount of foam accumulation reaches its maximum, and a later polymerization phase from the point when the height of the foam accumulation layer reaches its maximum until the end of oxidation polymerization. A method for producing polyphenylene ether, characterized in that the deactivation step is carried out such that the polymerization time in the later stage of polymerization accounts for 40 to 60% of the total polymerization time of the oxidative polymerization step. 【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), each R 31 is independently a linear alkyl group having 1 to 8 carbon atoms which may be optionally substituted, or a cyclic alkyl structure having 1 to 8 carbon atoms formed by two R 31 bonded to each other, and each R 32 is independently an alkylene group having 1 to 8 carbon atoms which may be optionally substituted, each b is independently 0 or 1, and R 33 is a hydrogen atom, an alkyl group having 1 to 8 carbon atoms which may be optionally substituted, or a phenyl group which may be optionally substituted.)

2. The method for producing polyphenylene ether according to claim 1, characterized in that the time from the point in time when the height of the foam deposit layer reaches its maximum to the point in time when the foam is reduced to 1 / 10 of that height is 25% or less of the time in the later stages of polymerization.

3. A method for producing polyphenylene ether according to claim 1, characterized in that the amount of oxygen-containing gas permeated during the pre-polymerization stage is 10 to 20 L / min per 1 kg of phenol, and the amount of oxygen-containing gas permeated during the post-polymerization stage is 0.5 to 9.9 L / min per 1 kg of phenol.

4. The phenol concentration in the solution during the initial polymerization stage is 15 to 25% by mass. The method for producing a polyphenylene ether according to claim 1, characterized in that, during the later stages of polymerization, an aromatic solvent is added to the solution to adjust the phenol concentration in the solution to 5% by mass or more and less than 15% by mass.

5. The method for producing polyphenylene ether according to claim 1, characterized in that the stirring speed (rpm) of the stirrer installed in the polymerization reactor is such that the stirring speed in the later stages of polymerization is 60% or less of the stirring speed in the earlier stages of polymerization.

6. A method for producing polyphenylene ether according to claim 1, characterized in that the temperature (°C) in the polymerization reactor during the later stage of polymerization is adjusted to less than 90% of the temperature in the polymerization reactor during the earlier stage of polymerization.

7. During the later stages of polymerization, water is added to the polymerization reactor. The method for producing polyphenylene ether according to claim 1, characterized in that the amount of water added is 1 to 10 parts by mass per 100 parts by mass of the solution.

8. The method for producing polyphenylene ether according to claim 7, characterized in that the amount of water added is 1 to 5 parts by mass per 100 parts by mass of the solution.

9. A method for producing polyphenylene ether according to claim 1, characterized in that, with respect to a total of 100 mol% of the phenols of formula (1) and formula (2), the content ratio of the phenol of formula (1) is 70 mol% or more and less than 85 mol%, and the content ratio of the phenol of formula (2) is more than 15 mol% and 30 mol% or less.

10. The phenol compound of formula (1) is 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 A method for producing polyphenylene ether according to claim 1, characterized in that it is one or more selected from the group consisting of 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.

11. The method for producing a polyphenylene ether according to claim 1, characterized in that the phenol compound of formula (2) is one or more selected from the group consisting of 2-isopropyl-5-methylphenol, 2-cyclohexyl-5-methylphenol, 2-tert-butyl-5-methylphenol, and 2-isobutyl-5-methylphenol.

12. A method for producing a polyphenylene ether according to claim 1, characterized in that the substructure represented by formula (3) is a t-butyl group.

13. The method for producing polyphenylene ether according to claim 1, characterized in that the solution further contains a phenol of the following formula (7). 【Chemistry 4】 (In formula (7), X is a single bond or any a-valent linking group, a is an integer from 1 to 6, R ４ k is either a linear alkyl group having 1 to 8 carbon atoms or a substructure represented by formula (3) above, and k is an integer from 1 to 4, independently of the others.

14. The phenol in formula (7) above is A phenol compound having two phenol units in its molecule, selected from the group consisting of 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,4'-methylenebis(2,6-dimethylphenol), bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxy-3,5-dimethylphenyl)sulfone, α,α'-bis(4-hydroxy-3,5-dimethylphenyl)-1,4-diisopropylbenzene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, and 1,1-bis(2-methyl-4-hydroxy-5-t-butylphenyl)butane; or; 4,4'-[(3-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(3-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 4,4'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(4-hydroxy-3-ethoxy [Phenyl)methylene]bis(2,3,6-trimethylethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 2,2'-[(4-hydroxyphenyl)methylene]bis(3,5,6-trimethylphenol), 4,4'-[4-(4-hydroxyphenyl)cyclohexylidene]bis(2,6-dimethylphenol), 4,4'-[(2-hydroxyphenyl)methylene] -Bis(2,3,6-trimethylphenol), 4,4'-[1-[4-[1-(4-hydroxy-3,5-dimethylphenyl)-1-methylethyl]phenyl]ethylidene]bis(2,6-dimethylphenol), 4,4'-[1-[4-[1-(4-hydroxy-3-fluorophenyl)-1-methylethyl]phenyl]ethylidene]bis(2,6-dimethylphenol), 2,6-bis[(4-hydroxy-3,5-dimethylphenyl)ethyl]-4-methylphenol, 2,6-bis[(4-hydroxy-2,3,6-trimethylphenyl] [(4-hydroxy-3,5,6-trimethylphenyl)methyl]-4-methylphenol, 2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-ethylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-methylphenol, 2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-methylphenol, 2,4-bis[(4-hydroxy-3-cyclohexylphenyl)methyl]-6-methylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-cyclohexylphenol, 2,4-bis[(2-hydroxy-5-methylphenyl)methyl]-6-cyclohexylphenol, 2,4-bis[(4-hydroxy-2,3,6-trimethylphenyl)methyl]-6-cyclohexylphenol, 3,6-bis[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,2-benzenediol, 4,6-bis[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,4,6-tris[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,4,6- ris[(2-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,2'-methylenebis[6-[(4 / 2-hydroxy-2,5 / 3,6-dimethylphenyl)methyl]-4-methylphenol], 2,2'-methylenebis[6-[(4-hydroxy-3,5-dimethylphenyl)methyl]-4-methylphenol], 2,2'-methylenebis[6-[(4 / 2-hydroxy-2,3,5 / 3,4,6-trimethylphenyl)methyl]-4-methylphenol], 2,2'-methylenebis[6-[(4-hydroxy-2, 3,5-trimethylphenyl)methyl]-4-methylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxyphenyl)methyl]-6-methylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxyphenyl)methyl]-3,6-dimethylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxy-3-methylphenyl)methyl]-3,6-dimethylphenol], 4,4'-methylenebis[2-[(2,3,4-trihydroxyphenyl)methyl]-3,6-dimethylphenol], 6,6'- Chilenbis[4-[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,2,3-benzenetriol], 4,4'-cyclohexylidenebis[2-cyclohexyl-6-[(2-hydroxy-5-methylphenyl)methyl]phenol], 4,4'-cyclohexylidenebis[2-cyclohexyl-6-[(4-hydroxy-3,5-dimethylphenyl)methyl]phenol], 4,4'-cyclohexylidenebis[2-cyclohexyl-6-[(4-hydroxy-2-methyl-5-cyclohexylphenyl)methyl]phenol], 4,A method for producing a polyphenylene ether according to claim 13, characterized in that the phenol compound is selected from the group consisting of 4'-cyclohexyllidenebis[2-cyclohexyl-6-[(2,3,4-trihydroxyphenyl)methyl]phenol], 4,4',4'',4'''-(1,2-ethanediylidene)tetrakis(2,6-dimethylphenol), 4,4',4'',4'''-(1,4-phenylenedimethylidene)tetrakis(2,6-dimethylphenol), and 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane and has three or more phenol units in the molecule.

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