JP2016074791A - Solvent recovery method in polyphenylene ether production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for recovering a solvent after polyphenylene ether production that can recover a high-purity good solvent and a poor solvent from a mixed liquid obtained by precipitating a polyphenylene ether from a polyphenylene ether solution and solid-liquid separating (filtering) the precipitated polyphenylene ether in the polyphenylene ether production.SOLUTION: A solvent recovery method in polyphenylene ether production includes: adding a poor solvent of a polyphenylene ether to a solution containing a polyphenylene ether and a good solvent of a polyphenylene ether to precipitate the polyphenylene ether and solid-liquid separating the precipitated polyphenylene ether; adding a metal salt and water to a mixed liquid of the good solvent and poor solvent obtained by the solid-liquid separation to liquid-liquid separate it into a phase of the good solvent and a mixed phase of the poor solvent and water; and recovering the poor solvent from the mixed phase obtained by the liquid-liquid separation.SELECTED DRAWING: None

Description

  The present invention relates to a solvent recovery method in the production of polyphenylene ether.

Resin compositions containing polyphenylene ether are excellent in electrical insulation, heat resistance, hydrolysis resistance, and flame retardancy, and are used in the fields of home appliances, OA equipment, automobile parts and the like.
Conventionally, various methods have been disclosed regarding a method for recovering a solvent used in the production after producing a polyphenylene ether by oxidative polymerization of a phenolic compound in a solution and separating the polyphenylene ether from the polymerization solution. Yes.
Generally, when a mixture of a polymerization solvent and methanol obtained by adding methanol to a solution to separate polyphenylene ether from a polymerization solution is an azeotropic mixture, it is possible to isolate both by distillation operation. Since it is difficult, as a method of recovering the polymerization solution, for example, methanol is extracted to the water side by bringing the filtrate into contact with water, and separated into methanol and water by distillation. At that time, for the purpose of preventing flooding of the distillation column There is a method using a specific additive (nonionic surfactant) (see, for example, Patent Document 1). In this method, when the mixture of methanol and water is separated into methanol and water by distillation, a nonionic surfactant can be added to the distillation column to give a good result to the flotation. It is said that.

JP 2001-348426 A

  However, in the recovery solvent (poor solvent) obtained by distillation recovery by adding a nonionic surfactant in the distillation column as in the method described in Patent Document 1, the solvent is stably recovered while removing the azeotropic mixture. It has not been done. In addition, the purity of the collected poor solvent tends to be low. When polyphenylene ether is separated (precipitated) from the polymerization solution using a poor solvent with low purity, the quality of the polyphenylene ether obtained by separation is good. Since the solvent content may be high, there is a problem that odor may be generated during the molding process.

  The present invention has been made in view of the above problems, and in the production of polyphenylene ether, a high-purity good solvent and poor solvent are obtained from a mixed liquid obtained by precipitating polyphenylene ether from a polyphenylene ether solution and solid-liquid separation (filtering). An object of the present invention is to provide a method for recovering a solvent after the production of polyphenylene ether.

In the production of polyphenylene ether, the present inventors added a metal salt and water to a mixed liquid obtained by precipitating polyphenylene ether from a polyphenylene ether solution and solid-liquid separating (filtering), and mixing a good solvent phase, a poor solvent and water. It was discovered that a high-purity solvent can be stably recovered by separating it into phases.
That is, the present invention is as follows.

[1]
A solvent recovery method in the production of polyphenylene ether,
To a solution containing polyphenylene ether and a good solvent for polyphenylene ether, a poor solvent for polyphenylene ether is added to precipitate polyphenylene ether, and solid-liquid separation is performed.
To the mixture of the good solvent and the poor solvent obtained by solid-liquid separation, a metal salt and water are added, and the liquid phase is separated into the good solvent phase and the mixed phase of the poor solvent and water,
A solvent recovery method for recovering a poor solvent from the mixed phase obtained by liquid-liquid separation.
[2]
In the mixed solution of the good solvent, the poor solvent, and water, water is added so that the mass of water is 0.5 to 2.0 times the mass of the poor solvent. Solvent recovery method.
[3]
In the mixed solution of the good solvent, the poor solvent and water, the metal salt is added so that the mass of the metal salt in the mixed solution is 1 to 10% of the mass of water in the mixed solution. The solvent recovery method according to [1] or [2] to be added.
[4]
The method for recovering a solvent according to any one of [1] and [2], wherein the cation in the metal salt is monovalent and / or divalent.

  ADVANTAGE OF THE INVENTION According to this invention, the solvent collection | recovery method in manufacture of polyphenylene ether which collect | recovers high purity solvents from the liquid mixture which filtered polyphenylene ether is realizable. Further, since the recovered poor solvent has a high purity, when it is used again for the separation of polyphenylene ether, the content of the good solvent in the produced polyphenylene ether is reduced, and the odor during molding can be suppressed.

  Hereinafter, a mode for carrying out the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. In addition, this invention is not limited to the following embodiment, It can implement by changing variously within the range of the summary.

[Solvent recovery method]
The solvent recovery method of the present embodiment includes, for example, adding a polyphenylene ether poor solvent to a polyphenylene ether solution produced by a polyphenylene ether production method described later, that is, a solution containing polyphenylene ether and a good solvent for polyphenylene ether. Then, the polyphenylene ether solid is precipitated and solid-liquid separated (solid-liquid separation step), and obtained by solid-liquid separation, a metal salt and water are added to the mixture of the good solvent and the poor solvent, Liquid-liquid separation into a good solvent phase and a mixed phase of the poor solvent and water (liquid-liquid separation step), and the poor solvent is recovered from the mixed phase obtained by liquid-liquid separation (recovery step).

-Production method of polyphenylene ether-
The method for producing polyphenylene ether that can be used in the present embodiment is a method in which an oxygen-containing gas is passed through a polymerization solution containing a phenolic compound, a good solvent for polyphenylene ether, and a catalyst to oxidatively polymerize the phenolic compound. Polymerization step. Specifically, in the polymerization step, a polymerization solution containing a phenolic compound, a good solvent for polyphenylene ether, and a catalyst contained in a reactor is prepared, and an oxygen-containing gas is passed through the polymerization solution in the reactor. Thus, the phenolic compound can be oxidatively polymerized to obtain polyphenylene ether in the solution.

--Polyphenylene ether--
The polyphenylene ether produced in the polymerization step in the method for producing polyphenylene ether that can be used in this embodiment will be described below. The polyphenylene ether produced by the polymerization step is not particularly limited, but specifically, it is a homopolymer or copolymer having a repeating unit represented by the following formula (1).

In the formula (1), R ₁ and R ₄ are each independently selected from the group consisting of hydrogen, primary or secondary lower alkyl, phenyl, aminoalkyl, and hydrocarbonoxy. Represent. In the formula (1), R ₂ and R ₃ each independently represent any one selected from the group consisting of hydrogen, primary or secondary lower alkyl, and phenyl.

  The homopolymer of polyphenylene ether is not particularly limited. Specifically, poly (2,6-dimethyl-1,4-phenylene) ether, poly (2-methyl-6-ethyl-1,4-phenylene) ) Ether, poly (2,6-diethyl-1,4-phenylene) ether, poly (2-ethyl-6-n-propyl-1,4-phenylene) ether, poly (2,6-di-n-propyl) -1,4-phenylene) ether, poly (2-methyl-6-n-butyl-1,4-phenylene) ether, poly (2-ethyl-6-isopropyl-1,4-phenylene) ether, poly (2 -Methyl-6-hydroxyethyl-1,4-phenylene) ether, poly (2-methyl-6-chloroethyl-1,4-phenylene) ether and the like. Among these, as the homopolymer, poly (2,6-dimethyl-1,4-phenylene) ether is preferable from the viewpoint that the raw materials are inexpensive and are easily available.

  The polyphenylene ether copolymer is a copolymer containing phenylene ether units as monomer units. The copolymer of polyphenylene ether is not particularly limited, and specifically, a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol, 2,6-dimethylphenol and o-cresol. And a copolymer of 2,6-dimethylphenol, 2,3,6-trimethylphenol and o-cresol. Among these, as the copolymer, a copolymer of 2,6-dimethylphenol and 2,3,6-trimethylphenol is preferable from the viewpoint that the raw materials are inexpensive and are easily available.

--- Phenolic compound ---
The polyphenylene ether can be produced by oxidative polymerization of a phenolic compound represented by the following formula (2).

In the formula (2), R ₅ and R ₇ are each independently selected from the group consisting of hydrogen, primary or secondary lower alkyl, phenyl, aminoalkyl, and hydrocarbonoxy. Represent. In the formula (2), R ₆ and R ₈ each independently represents any one selected from the group consisting of hydrogen, primary or secondary lower alkyl, and phenyl.

  The phenolic compound is not particularly limited. Specifically, 2,6-dimethylphenol, 2,3,6-trimethylphenol, 2-methyl-6-ethylphenol, 2,6-diethylphenol, 2 -Ethyl-6-n-propylphenol, 2-methyl-6-chlorophenol, 2-methyl-6-bromophenol, 2-methyl-6-isopropylphenol, 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, 2,6-bis- (4-fluorophenyl) phenol, 2-methyl-6-tolylphenol 2,6-di-tolyl phenols, and the like. These phenolic compounds may be used alone or in combination of two or more. Further, even if the solvent used as the polymerization solution contains a small amount of phenol, o-cresol, m-cresol, p-cresol, 2,4-dimethylphenol, 2-ethylphenol, etc. as an impurity, it is one of the phenolic compounds. Since it is consumed as a part by the polymerization reaction and incorporated into the polyphenylene ether, there is no problem.

  Among these, the phenolic compound is preferably 2,6-dimethylphenol or a mixture of 2,6-dimethylphenol and 2,3,6-trimethylphenol, and 2,6-dimethylphenol is preferable. More preferred.

-Good solvent for polyphenylene ether-
In the present invention, the good solvent for polyphenylene ether is the solubility of poly (2,6-dimethyl-1,4-phenylene) ether at 20 ° C. (the solute (poly (2,6-dimethyl-1, 4-phenylene) ether) refers to a solvent having a mass (g)) of 1 or more. The good solvent is not particularly limited, but an aromatic solvent is particularly preferable.

  Examples of such aromatic solvents include aromatic hydrocarbons such as benzene, toluene, xylene, and ethylbenzene; halogenated aromatic hydrocarbons such as chlorobenzene, dichlorobenzene, and trichlorobenzene; nitro compounds such as nitrobenzene, and the like. Can be mentioned. Among these, the aromatic solvent is preferably at least one selected from the group consisting of toluene, xylene, and ethylbenzene, and more preferably toluene.

As the aromatic solvent used in the polymerization step, those which are substantially incompatible with water can be preferably used. As those that are substantially incompatible with water, aromatic hydrocarbon solvents such as toluene and xylene are preferred.
In addition, the polymerization form in the polymerization process is changed by selecting the ratio of good solvent and poor solvent for polyphenylene ether, which is a polymer obtained by oxidative polymerization of a phenolic compound, and by increasing the ratio of good solvent, The polymerization method becomes a precipitation polymerization method in which the polymer is precipitated as particles in the reaction solvent as the reaction proceeds by increasing the ratio of the poor solvent. In the polymerization step of the present embodiment, the polymerization form is not particularly limited, and the polymerization form can be selected by adjusting the amount of the poor solvent added to the good solvent as necessary.

  In order to change the polymerization form in the polymerization process, if necessary, a good solvent can be mixed with a solvent or a poor solvent having a property compatible with water, or a good solvent and a property compatible with water. It is possible to use a solvent having a solvent and a poor solvent. Although it does not specifically limit as a solvent which has a property compatible with water, Specifically, Alcohols, such as methanol, ethanol, and propanol; Ketones, such as acetone and methyl ethyl ketone; Esters, such as ethyl acetate and ethyl formate; Examples thereof include amides such as dimethylformamide; sulfoxides such as dimethyl sulfoxide. One or more of these solvents can be used in combination of two or more if necessary.

--Catalyst--
The catalyst that can be used in the polymerization step is to efficiently oxidatively polymerize the phenolic compound and produce polyphenylene ether by passing an oxygen-containing gas through a polymerization solution composed of the phenolic compound, a solvent, and the catalyst. Therefore, it is an effective oxidation catalyst.

  The catalyst is not particularly limited, and specifically, a catalyst comprising a copper compound, a bromine compound, and one or more selected from the group consisting of a diamine compound, a tertiary monoamine compound, and a secondary monoamine compound. A catalyst containing a copper compound, a bromine compound, a diamine compound, a tertiary monoamine compound, and a secondary monoamine compound as essential components is more preferable.

  Although it does not specifically limit as a copper compound used as a component of a catalyst, Specifically, a cuprous compound, a cupric compound, or mixtures thereof can be used. Although it does not specifically limit as a cuprous compound, Specifically, cuprous oxide, cuprous chloride, cuprous bromide, cuprous sulfate, cuprous nitrate, etc. are mentioned. Moreover, although it does not specifically limit as a cupric compound, Specifically, cupric chloride, cupric bromide, cupric sulfate, cupric nitrate, etc. are mentioned. Among these, preferred compounds for cuprous and cupric compounds are cuprous oxide, cuprous chloride, cupric chloride, cuprous bromide and cupric bromide. In addition, these copper salts may be synthesized at the time of use from copper oxide, copper carbonate carbonate, copper hydroxide, and the like, and the corresponding halogen or acid. For example, cuprous bromide can be obtained by mixing cuprous oxide and hydrogen bromide (solution thereof). A preferable copper compound is a cuprous compound. These copper compounds may be used alone or in combination of two or more.

  Although it does not specifically limit as a bromine compound used as a component of a catalyst, Specifically, hydrogen bromide, sodium bromide, potassium bromide, tetramethylammonium bromide, tetraethylammonium bromide, etc. are mentioned. These bromine compounds may be used in the form of an aqueous solution or a solution using an appropriate solvent. These bromine compounds may be used alone or in combination of two or more.

  A preferable combination of the above-described copper compound and bromine compound is an aqueous solution of cuprous oxide and hydrogen bromide. Although the usage-amount of these compounds is not specifically limited, 2 times mole or more and 10 times mole or less are preferable as a bromine atom with respect to the molar amount of a copper atom. Moreover, it is preferable that it is the range of 0.02 mol-0.6 mol as a copper atom with respect to 100 mol of phenolic compounds.

Although the diamine compound used as a component of a catalyst is not specifically limited, Specifically, the diamine compound etc. which are represented by following formula (3) are mentioned. Among the diamine compounds represented by the formula (3), N, N′-di-t-butylethylenediamine is preferable. Although the usage-amount of a diamine compound is not specifically limited, It is 0.5 times mole amount or more with respect to the mol number of the copper atom normally used, and an upper limit is not specifically limited.

In the formula (3), R ₉ , R ₁₀ , R ₁₁ and R ₁₂ are each independently hydrogen or a linear or branched alkyl group having 1 to 6 carbon atoms, and all are not hydrogen at the same time. . R ₁₃ is a C 2-5 linear or methyl branched alkylene group.

  Although it does not specifically limit as a tertiary monoamine compound used as a component of a catalyst, Aliphatic tertiary amine including an alicyclic tertiary amine, etc. are mentioned. The tertiary monoamine compound is not particularly limited, and specifically, trimethylamine, triethylamine, tripropylamine, tributylamine, triisobutylamine, dimethylethylamine, dimethylpropylamine, allyldiethylamine, dimethyl-n-butylamine, diethylisopropyl. Examples thereof include amines and N-methylcyclohexylamine. These tertiary monoamines may be used alone or in combination of two or more. Although the usage-amount of a tertiary monoamine compound is not specifically limited, The range of 0.1 mol-15 mol is preferable with respect to 100 mol of phenolic compounds.

  Although it does not specifically limit as a secondary monoamine compound used as a component of a catalyst, Specifically, a 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 (substituted or unsubstituted phenyl) Examples thereof include alkanolamine and N-hydrocarbon substituted aniline.

  Although it does not specifically limit as said N (substituted or unsubstituted phenyl) alkanolamine, Specifically, N-phenylmethanolamine, N-phenylethanolamine, N-phenylpropanolamine, N- (m-methylphenyl) Examples include ethanolamine, N- (p-methylphenyl) ethanolamine, N- (2 ′, 6′-dimethylphenyl) ethanolamine, N- (p-chlorophenyl) ethanolamine and the like.

  The N-hydrocarbon substituted aniline is not particularly limited, and specifically includes N-ethylaniline, N-butylaniline, N-methyl-2-methylaniline, N-methyl-2,6-dimethylaniline, Examples include diphenylamine, but are not limited to these examples. These secondary monoamine compounds may be used alone or in combination of two or more.

  Although the usage-amount of a secondary monoamine compound is not specifically limited, Generally it is the range of 0.05 mol-15 mol with respect to 100 mol of phenolic compounds.

-Other materials-
In the polymerization step, in the polymerization solution, at least any selected from the group consisting of a tetraalkylammonium salt compound, a polyethylene glycol group-containing alkylamine, and a polyethylene glycol group-containing alkylammonium salt compound in a range not exceeding 0.1 mass%. It may be included. Thereby, the efficiency of the polymerization reaction can be improved. Examples of such a compound include those having a structure represented by the following formula (4), (5) or (6).

式（４）において、Ｒ₁₄、Ｒ₁₅、Ｒ₁₆、Ｒ₁₇は、それぞれ独立して炭素数１〜２２の直鎖状又は分岐状アルキル基であり、Ｘは対となる陰イオン、好ましくはＣｌ^-、Ｂｒ^-より選択される陰イオンである。

In the formula (4), R ₁₄ , R ₁₅ , R ₁₆ and R ₁₇ are each independently a linear or branched alkyl group having 1 to 22 carbon atoms, and X is a paired anion, preferably Cl ^-, Br ^- is an anion selected from.

式（５）において、Ｒ₁₈は、炭素数１〜２２の直鎖状又は分岐状アルキル基を表し、Ｒ₁₉はＲ₁₈に定義した基に加え、−（ＣＨ₂ＣＨ₂Ｏ）_n−Ｈ［ｎは１〜４０の整数］で表される基であってもよく、Ｒ₂₀は−（ＣＨ₂ＣＨ₂Ｏ）_n−Ｈ［ｎは１〜４０の整数］で表される基である。

In the formula (5), R ₁₈ represents a linear or branched alkyl group having 1 to 22 carbon atoms, and R ₁₉ is — (CH ₂ CH ₂ O) _n —H in addition to the group defined as R _18. [N may be a group represented by an integer of 1 to 40], and R ₂₀ is a group represented by — (CH ₂ CH ₂ O) _n —H [n is an integer of 1 to 40]. .

式（６）において、Ｒ₂₁、Ｒ₂₂は、炭素数１〜２２の直鎖状又は分岐状アルキル基を表し、Ｒ₂₃は、Ｒ₂₁に定義した基に加え、−（ＣＨ₂ＣＨ₂Ｏ）_n−Ｈ［ｎは１〜４０の整数］で表される基であってもよく、Ｒ₂₄は、−（ＣＨ₂ＣＨ₂Ｏ）_n−Ｈ［ｎは１〜４０の整数］で表される基であり、Ｘは対となる陰イオン、好ましくはＣｌ^-、Ｂｒ^-より選択される陰イオンである。

In Formula (6), R ₂₁ and R ₂₂ represent a linear or branched alkyl group having 1 to 22 carbon atoms, and R ₂₃ is — (CH ₂ CH ₂ O) in addition to the group defined as R _21. ) _N —H [n is an integer of 1 to 40], and R ₂₄ is — (CH ₂ CH ₂ O) _n —H [n is an integer of 1 to 40]. is a group, X is a pair anion, preferably Cl ^-, Br ^- is an anion selected from.

  In the polymerization step, among the other materials described above, it is preferable to use trioctylmethylammonium chloride known under the trade names of Aliquat 336 (manufactured by Henkel) and Capriquat (manufactured by Dojindo Laboratories).

-Preparation of polymerization solution-
The polymerization solution in the polymerization step may be prepared by introducing the phenolic compound, the solvent, and the catalyst component into the reactor individually. Alternatively, the phenolic compound and the catalyst are dissolved in the solvent in advance, and then reacted. A method in which a catalyst previously dissolved in a part of the solvent is first introduced into the reactor and then a phenolic compound dissolved in the remaining solvent is introduced into the reactor is preferable.

  The polymerization solution in the polymerization step is preferably adjusted to 0 to 80 ° C., more preferably 10 to 60 ° C., and more preferably 20 to 50 ° C. from the viewpoint of reaction progress and catalyst activity. Further preferred. It is preferable to set the temperature lower in the first half of the polymerization step and higher in the second half of the polymerization step. Thereby, the progress of the polymerization reaction tends to be further promoted.

The polymerization solution is preferably prepared in a blending amount of 10 to 25 parts by mass of the phenolic compound, 75 to 90 parts by mass of the solvent, and 0.1 to 10 parts by mass of the catalyst. Here, the total mass part of the phenolic compound and the solvent is 100 parts by mass. By setting it as such a compounding quantity, it exists in the tendency for the effect which polyphenylene ether polymerization control is stabilized to be acquired. The amounts of the phenolic compound, solvent, and catalyst in the polymerization solution are the mass ratio at the time when introduction of the phenolic compound, solvent, and catalyst into the reactor is completed.
A polymerization solution containing 12 to 23 parts by mass of a phenolic compound, 77 to 88 parts by mass of a solvent, and 0.5 to 9 parts by mass of a catalyst is more preferable, 13 to 21 parts by mass of a phenolic compound, 79 to 87 parts by mass of a solvent, and A polymerization solution containing 0.8 to 8 parts by mass of the catalyst is more preferable. By setting it as the said preferable range, it exists in the tendency for polyphenylene ether polymerization control to become more stable.

  Moreover, it is preferable that the polyphenylene ether in a polyphenylene ether polymerization solution is 10-30 mass% with respect to a polyphenylene ether solution.

--Oxygen-containing gas ventilation--
Oxidative polymerization in the polymerization step can be started by aeration of oxygen-containing gas, but the timing of aeration start of oxygen-containing gas is not particularly limited, but in the preparation of the polymerization solution, any of phenolic compounds, solvents, and catalysts is reacted. It is preferable to start venting the oxygen-containing gas after introduction into the vessel.

  Although it does not specifically limit as oxygen-containing gas, Specifically, what mixed oxygen and arbitrary inert gas, the air, or what mixed air and arbitrary inert gas can be used. Although it does not specifically limit as an inert gas, Specifically, arbitrary things can be used if the influence with respect to a polymerization reaction is not large. A typical inert gas is nitrogen.

  The oxygen-containing gas is not particularly limited, but specifically, one having an oxygen concentration of 5 to 25% by volume is preferable, and one containing a nitrogen-containing gas and air and having an oxygen concentration of 6 to 20% by volume. More preferably, it contains nitrogen-containing gas and air, and more preferably has an oxygen concentration of 8 to 12% by volume. With such a preferable oxygen concentration, the gradual heating, the polymerization rate and the like tend to be more stable.

  In addition, when the oxygen concentration of the unreacted gas in the oxygen-containing gas after venting exceeds 11.6% by volume, an inert gas such as nitrogen is introduced into the gas phase of the reactor, and the oxygen concentration is 11.6%. It is preferable to control the volume% or less. Thereby, the explosion of the solvent used can be prevented.

  The air flow rate of the oxygen-containing gas is not particularly limited, but is preferably 0.5 NL / min to 15 NL / min, more preferably 3 NL / min to 14 NL / min, more preferably 6 NL / min with respect to 1 kg of the phenolic compound subjected to the polymerization reaction. ˜13 NL / min is more preferable. By setting the aeration amount to 0.5 NL / min or more, the target polyphenylene ether quickly reaches the desired molecular weight, and the productivity tends to be improved. On the other hand, by setting the ventilation rate to 15 NL / min or less, problems such as excessive equipment and an increase in the amount of exhaust gas can be avoided, and the economy tends to be excellent.

--- Termination of polymerization--
The method for producing polyphenylene ether that can be used in the present embodiment preferably includes a polymerization stopping step of stopping the polymerization reaction when the target degree of polymerization is reached after performing the polymerization step as described above. . The termination of the polymerization reaction is not particularly limited, and a conventionally known method can be applied. As a normal stopping method, an acid such as hydrochloric acid or acetic acid, or an aqueous chelating agent solution such as nitrilotriacetic acid and its salt is added to the polymerization solution to deactivate the catalyst, thereby stopping the polymerization.

The chelating agent aqueous solution is a water-soluble chelating agent. When a metal salt is used as a catalyst, the chelating agent forms a chelate with the metal salt and efficiently removes the metal salt from the polymerization solution. As the chelating agent aqueous solution, an aqueous solution of ethylenediaminetetraacetate can be preferably used. As the chelating agent aqueous solution, one or more compounds selected from ethylenediaminetetraacetic acid tetrasodium salt aqueous solution, ethylenediaminetetraacetic acid trisodium salt aqueous solution, ethylenediaminetetraacetic acid tetrapotassium aqueous solution, and ethylenediaminetetraacetic acid tripotassium aqueous solution are more preferably used. it can.
In addition, it is preferable that the polyphenylene ether solution of the present embodiment is obtained by substantially removing a metal salt as a catalyst, a metal salt of a chelating agent, and water from the polymerization solution.

In the polymerization stopping step, preferably, after stopping the polymerization by contacting with the chelating agent aqueous solution, the mixture is kept at 40 ° C. to 100 ° C. until the by-product diphenoquinone disappears during the polymerization, and is contacted for 30 minutes to 150 minutes. Separating the catalyst.
In addition, when using a chelating agent aqueous solution in the polymerization termination step, the polyphenylene ether solution is not miscible with the chelating agent aqueous solution in which the catalytic metal is captured, and thus can be easily separated only by standing the solution. Alternatively, mechanical separation can be performed using a centrifuge or the like.

-Solid-liquid separation process-
In the solid-liquid separation step, first, a poor solvent of polyphenylene ether is added to a solution (polymerization solution) containing polyphenylene ether and a good solvent of polyphenylene ether, and the poor solvent is brought into contact with the solution to obtain polyphenylene ether. For example, it is deposited as a particulate solid. The precipitated polyphenylene ether is solid-liquid separated from a mixed solution containing a polymerization solvent and a poor solvent by a centrifuge or vacuum filtration continuously or batchwise. The recovered polyphenylene ether is sent to a drying process for commercialization.

--Polyphenylene ether poor solvent--
The poor solvent of polyphenylene ether forms an azeotrope with the above-mentioned good solvent of polyphenylene ether, but does not form an azeotrope with water, and alone has a lower boiling point than water. Preferable examples include alcohols such as methanol and ethanol, and aliphatic ketones such as acetone. Of these, methanol is most preferred because it has the best anti-solvent properties and dissolves well in water. In some cases, the above-mentioned polymerization solvent for polyphenylene ether may be present in the poor solvent as long as it does not interfere with the precipitation of polyphenylene ether.
In the present invention, the poor solvent for polyphenylene ether does not dissolve poly (2,6-dimethyl-1,4-phenylene) ether at all, or poly (2,6-dimethyl-1,4-phenylene at 20 ° C. A solvent in which the solubility of (phenylene) ether is less than 1.

-Liquid-liquid separation process-
The mixed liquid composed of a good solvent and a poor solvent, which is solid-liquid separated by filtering the precipitated polyphenylene ether, is sent to a liquid-liquid separation step for recycling, for example. In the mixed solution containing the good solvent and the poor solvent, a polymerization solvent and / or a poor solvent derived from other steps may be mixed. In the present embodiment, when the good solvent and the poor solvent are azeotropic mixtures, it is difficult to separate them by distillation. Therefore, in the liquid-liquid separation step, first, the good solvent and A metal salt and water are added to a mixed solution containing a poor solvent and brought into contact with each other to extract the poor solvent on the aqueous phase side, thereby enabling liquid-liquid separation between the good solvent and the poor solvent. In addition, addition of the metal salt and water to a liquid mixture can be added as metal salt water solubility, or can also be added separately, respectively.

  In the extraction of the poor solvent, the mass of water is 0.5 to 2.0 times the mass of the poor solvent ((the mass of water) / (the poor solvent) in the mixture of the good solvent, the poor solvent, and water. It is preferable to add water so that it may become mass) = 0.5-2.0). By setting the mass ratio to 0.5 times or more, the extraction of the target poor solvent is good and the productivity tends to be improved. On the other hand, by setting the mass ratio to 2.0 times or less, the problem that the operation cost of the recovery facility increases can be avoided, and the economy tends to be excellent. From the same viewpoint, the mass of water is more preferably 0.8 to 1.5 times the mass of the poor solvent. In addition, since the water contained in the “mixture of good solvent, poor solvent and water” may already contain water when it is subjected to solid-liquid separation, the mass of the water already contained is determined. In consideration, the mass of water in the mixed solution is used to define the mass ratio of the poor solvent to water.

  In the extraction of the poor solvent, the mass of the metal salt in the mixture is 1 to 10% of the mass of the water in the mixture (the metal salt in the mixture of the good solvent, the poor solvent, and water. Of the metal salt) / (mass of water) × 100 = 1 to 10%). When the mass of the metal salt is 1% or more of the mass of water in the mixed solution, the purity after separation tends to be high, and when the mass is 10% or less, the progress of deterioration due to corrosion of the recovery equipment. Tend to be suppressed. In addition, from the same viewpoint, it is more preferable that the mass of the metal salt is 3 to 10% of the mass of water in the mixed solution, and 5 to 10% is even more preferable.

  As the metal salt, the cation in the metal salt is preferably monovalent and / or divalent. This is because the metal salt is inexpensive and can be stably obtained. Specific metal salts are not particularly limited, but specific examples include magnesium chloride, potassium chloride, sodium chloride, magnesium sulfate, potassium sulfate, sodium sulfate, ammonium sulfate, sodium bromide, potassium bromide, bromide. Examples thereof include magnesium. Among these, as the metal salt, an alkali metal salt is preferable from the viewpoint of easy availability. These metal salts may be used in the state of an aqueous solution. These metal salts may be used alone or in combination of two or more.

The good solvent and the mixed phase of the poor solvent and water (hereinafter also referred to as “mixed phase”) extracted as described above can be separated only by standing, but they can be separated using a centrifuge or the like. May be separated.
In addition, water is added together with the metal salt in the liquid-liquid separation step even if residual components such as oligomer components are contained in the mixed liquid consisting of the recovered good and poor solvents obtained by solid-liquid separation. Liquid-liquid separation, so the mixed phase after the liquid-liquid separation step does not contain residual components, and therefore prevents troubles in the recovery equipment in the recovery of the poor solvent from the mixed phase in the recovery step described later can do.

-Recovery process-
The recovery step after the liquid-liquid separation is not particularly limited, but the poor solvent is removed from the mixed phase by, for example, distillation, paver percolation (membrane separation) or ultra-high speed centrifugation. to recover. If necessary, the good solvent phase is recovered from the good solvent phase in the same manner. In addition, it is preferable to collect | recover by distillation from a viewpoint of cost reduction.

  The good solvent recovered from the good solvent phase is allowed to contain a little poor solvent. For example, the good solvent phase can be used as it is as a solvent for the polymerization solution of polyphenylene ether.

When the solvent recovery method of the present invention is used, the recovery efficiency is greatly improved over the conventional polyphenylene ether good solvent recovery method, and the purity of the poor solvent of the recovered polyphenylene ether is improved. Greatly improve the equipment and energy required for
In addition, when polyphenylene ether is precipitated using a high-purity poor solvent recovered by the above method, the content of good solvent in the produced polyphenylene ether is reduced, and odor during molding can be reduced. Moreover, the drying time of polyphenylene ether can be shortened.

  As a preferable form in the method for producing polyphenylene ether that can be used in this embodiment, 2,6-dimethylphenol is used as a phenolic compound, cuprous oxide as a copper compound, and hydrogen bromide as a bromine compound. (Used in aqueous solution), N, N′-di-t-butylethylenediamine as diamine compound, N, N-di-n-butylamine as secondary monoamine compound, N, N-dimethyl-n-butylamine as tertiary monoamine Although using what is a form which used 5 components together is mentioned, the manufacturing method of polyphenylene ether which can be used by this embodiment is not limited to this form.

[Characteristics of polyphenylene ether]
-Reduced viscosity-
The polyphenylene ether obtained by the method for producing polyphenylene ether that can be used in this embodiment preferably has a reduced viscosity (ηsp / c) of 0.3 to 1.0 dL / g. The reduced viscosity is a value measured under a temperature condition of 30 ° C. using a 0.5 g / dL chloroform solution. The reduced viscosity is more preferably in the range of 0.3 to 0.8 dL / g, and still more preferably in the range of 0.3 to 0.6 dL / g.
When the reduced viscosity is 0.3 dL / g or more, the original mechanical strength of polyphenylene ether tends to be obtained. Moreover, it exists in the tendency for the effect which suppresses the excessive molecular weight rise at the time of polyphenylene ether polymerization to be acquired because the said reduced viscosity is 1.0 dL / g or less.
As another control method of the reduced viscosity, the reduced viscosity tends to increase by increasing the catalyst amount and air flow rate and increasing the reaction time. Conversely, the reaction time can be reduced by lowering the catalyst amount and flow rate. Shortening tends to reduce the reduced viscosity.

  Hereinafter, the present invention will be specifically described with reference to specific examples and comparative examples. However, the present invention is not limited to the following examples. Measuring methods for physical properties and characteristics, etc. applied to the examples and comparative examples are shown below.

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

(Quantification of composition in solvent)
It quantified using the gas chromatograph (Shimadzu Corp. make: GC-20100). Column: HR-1 (L: 30 m ID: 0.25 mm Film thickness: 0.25 μm), carrier gas: helium, sample inlet temperature is 300 ° C., column temperature is 50 ° C. to 20 ° C. Each component was quantified from the separated gas, which was detected by a flame ionization detector, kept at 250 ° C./min.
The undetectable moisture was quantified using a Karl Fischer coulometric moisture meter (Mitsubishi Chemical Corporation: CA-200). Electrolytic solution: Iodine ions, sulfur dioxide, and alcohol were used, and iodine was generated from iodide ions at the anode by electrolysis in an electrolytic solution (anodic), and the amount of water was converted from the amount of electricity according to Faraday's law.

[Example 1]
The reactor is a cylindrical reactor with a maximum height of 15 cm and an inner diameter of 6 cm for containing the reaction liquid, and a sparger for introducing an oxygen-containing gas, a stirring turbine blade, and a sampling discharge valve are provided at the bottom. A 5 liter jacket equipped with a baffle on the side of the reactor and a temperature control device, and equipped with a reflux condenser with a polymerization solution component inlet at the top of the reactor and a decanter for condensate separation in the vent gas line An attached glass reactor was used.
The distillation apparatus is a rectification apparatus with 20 concentrating stages, 20 recovering stages, and 45 mm inner diameter. A distillation liquid extraction line is provided at the uppermost and lowermost stages, and a feed port is provided at a position of 20 stages from the top. A glass continuous Oldershaw type distillation apparatus equipped with a reflux condenser was used.

(Production of polyphenylene ether and solid-liquid separation process)
2,6-dimethylphenol; 0.20 kg, toluene; 1.30 kg, and catalyst (0.4 g cuprous oxide, 2.0 g 47% aqueous hydrogen bromide, 0.6 g di-t-butylethylenediamine) , 3.0 g of di-n-butylamine, 9.0 g of butyldimethylamine); 15.0 g, and then introduced into the reactor, the liquid temperature being 40 ° C., oxygen The gas contained was passed through a sparger to oxidatively polymerize 2,6-dimethylphenol. Sampling is started little by little after the polymerization solution starts to become somewhat viscous, and the time required for ηsp / c to reach a specific value (in this example, ηsp / c = 0.74 ± 0.01 dL from the start of polymerization) Polymerization time until reaching / g) was defined as polymerization time. 150 minutes after the start of oxidative polymerization, 10% aqueous solution of ethylenediaminetetraacetic acid tetrasodium salt (Dojindo Laboratories reagent); 0.17 kg was added to stop the oxidative polymerization, and after washing with 1.95 kg of methanol, solid liquid The liquid was separated with a separator and dried at 140 ° C. for 120 minutes to obtain polyphenylene ether.
(Liquid-liquid separation process)
Water (2.78 kg) and sodium chloride (0.03 kg) were added to the filtrate (3.42 kg) subjected to solid-liquid separation so that the water / methanol mass ratio after addition was 1.5, and the mixture was stirred for 1 minute. Then, the liquid mixture was isolate | separated with the centrifuge made from a Sharpless company, and the toluene phase of Example 1 and the methanol-water phase (The water phase containing methanol as a poor solvent) were obtained. The amount of each component of the obtained methanol / water phase liquid was quantified. The results are shown in Table 1.
(Recovery process)
The methanol / water phase liquid-liquid separated was continuously introduced into the distillation apparatus, and subjected to atmospheric distillation at bottom temperature = 111 ° C., top temperature = 66 ° C., reflux ratio = 1.0. Methanol was obtained. About the obtained methanol phase liquid, the amount of toluene components was quantified. The results are shown in Table 1.

(Polyphenylene ether precipitated using the recovered poor solvent)
Using the recovered methanol, polyphenylene ether was precipitated in the same manner as described above. The amount of good solvent in the obtained polyphenylene ether was measured.

[Examples 2-6, Comparative Examples 1-3]
The filtrate obtained by solid-liquid separation was subjected to the same operation as in Example 1 with the substances and amounts shown in Table 1. The results are shown in Table 1.
[Examples 7 to 12]
The filtrate was subjected to solid-liquid separation, and the same operation as in Example 1 was performed using the substances and amounts shown in Table 2. The results are shown in Table 2.

  The solvent recovery method in the production of the polyphenylene ether of the present invention has industrial applicability as a production technique for materials such as automobile parts, heat-resistant parts, electronic equipment parts, and industrial parts.

Claims (4)

A solvent recovery method in the production of polyphenylene ether,
To a solution containing polyphenylene ether and a good solvent for polyphenylene ether, a poor solvent for polyphenylene ether is added to precipitate polyphenylene ether, and solid-liquid separation is performed.
To the mixture of the good solvent and the poor solvent obtained by solid-liquid separation, a metal salt and water are added, and the liquid phase is separated into the good solvent phase and the mixed phase of the poor solvent and water,
A solvent recovery method for recovering a poor solvent from the mixed phase obtained by liquid-liquid separation.   The solvent recovery according to claim 1, wherein water is added so that the mass of water is 0.5 to 2.0 times the mass of the poor solvent in a mixture of the good solvent, the poor solvent and water. Method.   In the mixed solution of the good solvent, the poor solvent and water, the metal salt is added so that the mass of the metal salt in the mixed solution is 1 to 10% of the mass of water in the mixed solution. The solvent recovery method according to claim 1 or 2, which is added.   The solvent recovery method according to claim 1, wherein the cation in the metal salt is monovalent and / or divalent.