CN107446125B

CN107446125B - Method for producing polyphenylene ether

Info

Publication number: CN107446125B
Application number: CN201611150611.XA
Authority: CN
Inventors: 新藤由幸; 山本繁
Original assignee: Asahi Kasei Corp
Current assignee: Asahi Kasei Corp
Priority date: 2016-05-31
Filing date: 2016-12-14
Publication date: 2020-07-14
Anticipated expiration: 2036-12-14
Also published as: JP2017214543A; JP6510473B2; SG10201610310PA; CN107446125A

Abstract

The present invention relates to a method for producing polyphenylene ether, which can significantly reduce the generation of transition products during troubles such as the increase of fine powder, the adhesion of scale in a precipitation tank, and the like, and the change of the type, and can efficiently obtain PPE. The method for producing PPE of the present invention is characterized by comprising the steps of: a polymerization step of subjecting a phenolic compound to oxidative polymerization in a polymerization solution containing a good solvent for PPE and a catalyst to obtain a PPE mixed solution; and a precipitation step of adding the PPE mixed solution, a poor solvent for PPE, and water to a precipitation tank equipped with a stirrer, mixing them, and precipitating PPE to obtain a slurry containing PPE particles, wherein in the precipitation step, the poor solvent for PPE and the water are added to the precipitation tank through different pipes, and in the precipitation step, the amount of water added is 0.05 to 30 mass% relative to 100 mass% of the poor solvent for PPE.

Description

Method for producing polyphenylene ether

Technical Field

The present invention relates to a method for producing polyphenylene ether (hereinafter sometimes abbreviated as "PPE"), and more particularly to a method for producing PPE powder having excellent quality and excellent productivity.

Background

A modified PPE resin made from PPE is a plastic material that can be used for producing products and parts having a desired shape by a molding method such as a melt injection molding method or a melt extrusion molding method, and is widely used as a material for products and parts in the electric and electronic fields, the automobile field, and other various industrial material fields.

As a method for producing PPE, there is a method of oxidatively polymerizing a phenolic compound in a good solvent for PPE in the presence of a copper compound and an amine. As a method for precipitating PPE from the PPE solution obtained by this method, the following methods are known: a poor solvent for PPE, such as methanol, containing water is added to a PPE solution containing a good solvent for PPE, thereby precipitating PPE particles.

In the PPE production process, there are cases where different types having different molecular weights are produced by changing the polymerization time, precipitation conditions, and the like. A transition product (not an intermediate product of any of the products before and after the variety change) is generated at the time of the variety change. Further, the deposition state during the variety change may be unstable until the composition in the deposition tank is changed.

In view of the reports on the precipitation of PPE in the related art, there are many techniques for improving the particle size such as the average particle size and the fine particle size, and there is no disclosure of a technique which can efficiently change the species and can continuously provide stable production even after the species change. That is, under the present circumstances, there is a demand for development of a precipitation method capable of reducing transient products in variety change and performing variety change in a stable state.

Patent document 1 includes a step of mixing a concentrated solution with an antisolvent to precipitate a poly (arylene ether) by setting the temperature of the concentrated solution immediately before mixing with the antisolvent to about (T)_cloudAt-10 ℃ or higher, generation of excessively fine particles can be suppressed.

In patent document 2, (a) this step is to mix a first mixture comprising a poly (arylene ether) and a solvent with a poor solvent to form a second mixture comprising the above solvent, the above poor solvent and the above poly (arylene ether), (b) to set an impeller tip speed of 6m/s or less, (c) to set a solid matter content of about 10% by mass to about 50% by mass relative to the above poly (arylene ether) resin, (d) to set a temperature of the above second mixture at least 5 ℃ lower than a boiling point of the above poor solvent, (e) to set a mass ratio of the above poor solvent to the above first mixture at about 0.5: 1 to about 4: 1, (f) preparing the poor solvent described above containing 5% by mass or less of water, thereby producing (i) a poly (arylene ether) having improved particle size characteristics with (i) particles having a particle size of less than 38 μm of about 50% by mass or less and (ii) an average particle size of 100 μm or more.

In patent document 3, a solution of an organic solvent for polyphenylene ether is prepared while maintaining a temperature of 60 ℃ to the boiling point of the organic solvent for polyphenylene ether, and an organic liquid in which polyphenylene ether is insoluble is added to the solution as quickly as possible while maintaining the above temperature range, thereby precipitating polyphenylene ether, recovering the precipitate, and drying it, thereby reducing the amount of fine particles.

In the techniques disclosed in patent documents 1 and 2, a PPE solution composed of PPE and a good solvent for PPE is mixed with a poor solvent such as methanol containing a small amount of water to precipitate PPE.

Documents of the prior art

Patent document

Patent document 1: japanese Kokai publication Hei-2004-531626

Patent document 2: japanese Kokai publication Hei-2014-508208

Patent document 3: japanese examined patent publication No. 45-587

Disclosure of Invention

Problems to be solved by the invention

In the methods described in patent documents 1 and 2, a mixing tank is required in order to contain a small amount of water in advance for methanol, and when conditions such as a variety change are changed, a transient product is generated until the composition of the mixing tank is changed.

The conventional PPE precipitation method is a technique for controlling the particle size of the precipitated PPE, and cannot sufficiently meet the industrial demand for stably producing high-quality PPE with high production efficiency.

Accordingly, an object of the present invention is to provide a method for producing PPE, which can stably operate without troubles such as an increase in fine powder, adhesion of scale to a precipitation tank, growth, detachment, and mixing of products during operation of the precipitation tank including a change in the type, can greatly reduce the amount of transient products generated during the change in the type, and can efficiently obtain PPE.

Means for solving the problems

In view of the above problems, the present inventors have studied a technique that can suppress a decrease in production efficiency due to the occurrence of transient products in response to a change in conditions such as a change in the type of PPE produced, can operate in a stable state, and can continue precipitation in a stable state even if the type is changed.

As a result, the following problems are found to occur: the precipitation becomes unstable and the amount of fine powder increases during the change of conditions such as the change of species; the scale deposits are generated and grow in the precipitation tank, and the scale deposits fall off and are mixed into the product, so that the quality is obviously reduced; and so on.

Therefore, the present inventors have tried to add a poor solvent and water separately without mixing them in advance in a precipitation tank using different pipes having different systems, and studied conditions under which transient products generated during the change of the types can be reduced and high-quality products can be stably produced after the change of the conditions.

Namely, the present invention is as follows.

[1]

A method for producing a polyphenylene ether, characterized by comprising the steps of:

a polymerization step of subjecting a phenolic compound to oxidative polymerization in a polymerization solution containing a good solvent for polyphenylene ether and a catalyst to obtain a polyphenylene ether mixed solution; and

a precipitation step of adding and mixing the polyphenylene ether mixed solution, a poor solvent for polyphenylene ether, and water to a precipitation tank having a stirrer to precipitate polyphenylene ether to obtain a slurry solution containing polyphenylene ether particles,

in the precipitation step, the poor solvent for polyphenylene ether and the water are fed to the precipitation tank through separate pipes,

in the precipitation step, the amount of water added is 0.05 to 30% by mass based on 100% by mass of the poor solvent for polyphenylene ether.

[2]

The method for producing a polyphenylene ether according to [1], wherein in the precipitation step, a ratio of a mass of the poor solvent for the polyphenylene ether to be added (a mass of the poor solvent for the polyphenylene ether to be added/a mass of the good solvent for the polyphenylene ether to be contained in the polyphenylene ether mixture to be added) to a mass of the good solvent for the polyphenylene ether to be contained in the polyphenylene ether mixture to be added is 0.3 to 2.0.

[3]

The process for producing a polyphenylene ether according to [1] or [2], wherein the phenolic compound is 2, 6-dimethylphenol.

[4]

The process for producing a polyphenylene ether according to any one of [1] to [3], wherein the content of polyphenylene ether particles having a particle diameter of 105 μm or less in the polyphenylene ether granules is 11% by mass or less.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the method for producing PPE of the present invention, it is possible to provide a method for producing PPE, which can be stably operated without troubles such as an increase in fine powder, adhesion of scale in a precipitation tank, growth, falling off, and mixing of product during operation of the precipitation tank including a change in the product type, and which can significantly reduce the amount of transient products generated during the change in the product type.

Drawings

FIG. 1 is a schematic view showing an example of a precipitation tank used in the production method of the present embodiment.

Fig. 2 is a schematic view of the guide shell in the precipitation tank used in the production method of the present embodiment, as viewed from above the precipitation tank.

Description of the symbols

1 precipitation tank

2 draft tube

3 stirring paddle

4 baffle

5 PPE Mixed solution supply port

6 poor solvent supply port

7 water supply port

8 liquid level

9 discharge port

Detailed Description

Hereinafter, a specific embodiment of the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the gist of the present invention.

[ method for producing polyphenylene ether ]

The method for producing PPE of the present embodiment includes the steps of:

a polymerization step of subjecting a phenolic compound to oxidative polymerization in a polymerization solution containing a good solvent for polyphenylene ether and a catalyst to obtain a polyphenylene ether mixed solution;

The method for producing PPE of this embodiment is preferably a continuous method.

The respective steps in the method for producing PPE of the present embodiment will be described in detail below.

(polymerization Process)

In the polymerization step, for example, the phenolic compound may be oxidatively polymerized by introducing an oxygen-containing gas into a polymerization solution containing a good solvent for PPE such as an aromatic solvent, a metal catalyst, a halogen compound, an amine compound, and the like.

Polymerization solution-

-phenolic compound- -

Examples of the phenol-based compound include o-cresol, 2, 6-dimethylphenol, 2-ethylphenol, 2-methyl-6-ethylphenol, 2, 6-diethylphenol, 2-n-propylphenol, 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-phenylphenol, and mixtures thereof, 2, 6-diphenylphenol, 2, 6-bis- (4-fluorophenyl) phenol, 2-methyl-6-tolylphenol, 2, 6-xylylphenol, 2, 5-dimethylphenol, 2,3, 6-trimethylphenol, 2, 5-diethylphenol, 2-methyl-5-ethylphenol, 2-ethyl-5-methylphenol, 2-allyl-5-methylphenol, 2, 5-diallylphenol, 2, 3-diethyl-6-n-propylphenol, 2-methyl-5-chlorophenol, 2-methyl-5-bromophenol, 2-methyl-5-isopropylphenol, 2-methyl-5-n-propylphenol, 2-methyl-6-propylphenol, 2-methyl-5-methylphenol, 2-methyl-5-n-propylphenol, 2-methyl-5, 2-ethyl-5-bromophenol, 2-methyl-5-n-butylphenol, 2, 5-di-n-propylphenol, 2-ethyl-5-chlorophenol, 2-methyl-5-phenylphenol, 2, 5-diphenylphenol, 2, 5-bis- (4-fluorophenyl) phenol, 2-methyl-5-tolylphenol, 2, 5-ditolylphenol, 2, 6-dimethyl-3-allylphenol, 2,3, 6-triallylphenol, 2,3, 6-tributylphenol, 2, 6-di-n-butyl-3-methylphenol, 2, 6-di-t-butyl-3-methylphenol, 2, 6-dimethyl-3-n-butylphenol, 2, 5-di-n-propylphenol, 2-methyl-5-chlorophenol, 2, 5-dimethylphenol, 2, 6-methyl-5-phenylphenol, 2, 2, 6-dimethyl-3-tert-butylphenol, and the like.

In particular, 2, 6-dimethylphenol, 2, 6-diethylphenol, 2, 6-diphenylphenol, 2,3, 6-trimethylphenol, and 2, 5-dimethylphenol are preferable because they are inexpensive and easily available, 2, 6-dimethylphenol, 2,3, 6-trimethylphenol are more preferable, and 2, 6-dimethylphenol is further more preferable.

The above phenol compounds may be used alone, or 2 or more kinds may be used in combination.

Examples of the 2 or more combinations include a combination of 2, 6-dimethylphenol and 2, 6-diethylphenol, a combination of 2, 6-dimethylphenol and 2, 6-diphenylphenol, a combination of 2,3, 6-trimethylphenol and 2, 5-dimethylphenol, a combination of 2, 6-dimethylphenol and 2,3, 6-trimethylphenol, and the like. The mixing ratio of the phenolic compounds to be combined can be arbitrarily selected.

The phenolic compound may contain a small amount of m-cresol, p-cresol, 2, 4-dimethylphenol, 2,4, 6-trimethylphenol, and the like, which are byproducts in the production.

Good solvents for polyphenylene ethers

Examples of the good solvent for the polyphenylene ether include aromatic solvents such as benzene, toluene, xylene, ethylbenzene, and styrene. Among them, toluene is preferred from the viewpoint of ease of removal of the residual solvent.

The good solvents for polyphenylene ether may be used alone or in combination of 2 or more.

Catalyst- -

As the above catalyst, a catalyst generally used for polymerization of PPE can be used.

Examples of the catalyst include a metal catalyst, a halogen compound, an amine compound, and a mixture thereof, and examples thereof include a mixture composed of a transition metal ion as a metal catalyst having redox ability and an amine compound capable of complexing with the transition metal ion, and specifically include a mixture composed of a copper compound and an amine compound, a mixture composed of a manganese compound and an amine compound, and a mixture composed of a cobalt compound and an amine compound. Among them, a mixture of a copper compound and an amine compound is preferable.

Metal catalyst

Among the above catalysts, a copper compound is preferable as the metal catalyst.

As the copper compound, a cuprous compound, a cupric compound, or a mixture thereof can be used. Examples of the cuprous compound include cuprous chloride, cuprous bromide, cuprous sulfate, and cuprous nitrate. Examples of the divalent copper compound include divalent copper oxide, copper chloride, copper bromide, copper sulfate, and copper nitrate. Among them, cupric oxide, cuprous chloride, cupric chloride, cuprous bromide, and cupric bromide are preferable.

These copper salts can be synthesized from copper oxide (e.g., cuprous oxide), copper carbonate, copper hydroxide, etc., and their corresponding halogens or acids (e.g., from cuprous oxide and hydrogen halide (or a solution of hydrogen halide)) at the time of use.

These metal catalysts may be used alone, or 2 or more kinds may be used in combination.

Halogen compounds

The halogen compound is not particularly limited, and specific examples thereof 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, tetraethylammonium iodide, and the like. These halogen compounds may be used in the form of an aqueous solution or a solution using an appropriate solvent. Among them, an aqueous solution of hydrogen chloride and an aqueous solution of hydrogen bromide are preferable.

These halogen compounds can be used alone, or more than 2 kinds can be used in combination.

Amine compound

Examples of the amine compound include diamine compounds, secondary monoamine compounds, tertiary monoamine compounds, and the like. Among them, the diamine compound is preferably contained, and the diamine compound, the secondary monoamine compound and the tertiary monoamine compound are more preferably contained.

The amine compounds can be used alone, or 2 or more kinds can be used in combination.

The diamine compound is preferably a diamine compound represented by the following general formula (1).

As the catalyst, for example, a catalyst containing a copper compound, a halogen compound, and a diamine compound represented by the following general formula (1) can be used. By using such a catalyst, the polymerization rate tends to be further increased and the polymerization time tends to be further shortened. Further, the molecular weight after polymerization tends to be more easily adjusted by adjusting the amount of the catalyst, the amount of oxygen blown, the polymerization time, and the like.

[ CHEM 1]

(in the formula (1), R₁、R₂、R₃And R₄Each independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, and not all of them represent a hydrogen atom. R₅Represents a linear or branched alkylene group having 2 to 5 carbon atoms. )

The diamine compound represented by the above general formula (1) is not particularly limited, and specific examples thereof include N, N ' -tetramethylethylenediamine, N ' -trimethylethylenediamine, N ' -dimethylethylenediamine, N-dimethylethylenediamine, N-methylethylenediamine, N ' -tetraethylethylenediamine, N ' -triethylethylenediamine, N ' -diethylethylenediamine, N ' -tetramethylethylenediamine, NDiethyl ethylenediamine, N-ethylethylenediamine, N, N-dimethyl-N ' -ethylethylenediamine, N, N ' -dimethyl-N-ethylethylenediamine, N-N-propylethylenediamine, N, N ' -di-N-propylethylenediamine, N-isopropylethylenediamine, N, N ' -diisopropylethylenediamine, N-N-butylethylenediamine, N, N ' -di-N-butylethylenediamine, N-isobutylethylenediamine, N, N ' -diisobutylethylenediamine, N-t-butylethylenediamine, N, N ' -di-t-butylethylenediamine, N, N, N ', N ' -tetramethyl-1, 3-diaminopropane, N, N, N ' -trimethyl-1, 3-diaminopropane, N, N ' -dimethyl-1, 3-diaminopropane, N-methyl-1, 3-diaminopropane, N, N, N ', N' -tetramethyl-1, 3-diamino-1-methylpropane, N, N, N ', N' -tetramethyl-1, 3-diamino-2-methylpropane, N, N, N ', N' -tetramethyl-1, 4-diaminobutane, N, N, N ', N' -tetramethyl-1, 5-diaminopentane, and the like. Among them, R in the formula (1) is preferable₅A diamine compound which is an alkylene group having 2 or 3 carbon atoms.

The diamine compounds can be used alone, or 2 or more kinds can be used in combination.

The amount of the diamine compound used is not particularly limited, and is preferably 0.01 to 10 moles per 100 moles of the phenolic compound.

The above-mentioned monovalent tertiary amine compound is not particularly limited, and specific examples thereof include aliphatic tertiary amines including alicyclic tertiary amines. Such a monovalent tertiary amine compound is not particularly limited, and specific examples thereof include trimethylamine, triethylamine, tripropylamine, tributylamine, triisobutylamine, dimethylethylamine, dimethylpropylamine, allyldiethylamine, N-butyldimethylamine, diethylisopropylamine, and N-methylcyclohexylamine.

The above-mentioned monovalent tertiary amine compounds may be used alone, or 2 or more kinds thereof may be used in combination.

The amount of the monovalent tertiary amine compound to be used is not particularly limited, but is preferably 15 mol or less based on 100 mol of the phenol compound.

The above-mentioned monovalent tertiary amine compound may be added in the whole amount before the polymerization, or may be added in part before the polymerization and further added in sequence during the polymerization. The tertiary monoamine may be added to the polymerization solution at the same time as the start of the polymerization after being mixed with the phenol compound.

The secondary monoamine compound is not particularly limited, and specific examples thereof include secondary aliphatic amines. The aliphatic secondary amine is not particularly limited, and specific examples thereof include dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-tert-butylamine, dipentylamine, dihexylamine, dioctylamine, didecylamine, dibenzylamine, methylethylamine, methylpropylamine, methylbutylamine, cyclohexylamine, and the like.

Further, as the secondary monoamine compound, a secondary monoamine compound containing an aromatic group may also be used. The aromatic-containing secondary monoamine compound is not particularly limited, and specific examples thereof include N- (substituted or unsubstituted phenyl) alkanolamines such as N-phenylmethanolamine, N-phenylethanolamine, N-phenylpropanolamine, N- (m-methylphenyl) ethanolamine, N- (p-methylphenyl) ethanolamine, N- (2 ', 6' -dimethylphenyl) ethanolamine, N- (p-chlorophenyl) ethanolamine, and the like; n-hydrocarbon-substituted anilines such as N-ethylaniline, N-butylaniline, N-methyl-2-methylaniline, N-methyl-2, 6-dimethylaniline and diphenylamine; and so on.

The secondary monoamine compounds can be used alone, also can be used in combination of 2 or more.

The amount of the secondary monoamine compound used is not particularly limited, but is preferably 15 mol or less based on 100 mol of the phenol compound.

In addition, a surfactant which has been known to have an effect of improving polymerization activity may be added to the polymerization solution.

Examples of the surfactant include trioctylmethylammonium chloride (trade name) known from Aliquat336 (manufactured by Henkel corporation) and CapRiquat (manufactured by college chemical research).

The amount of the surfactant used is preferably not more than 0.1% by mass based on the total amount of the polymerization solution.

Aeration of oxygen-containing gases

In the polymerization step, the phenol compound may be polymerized while aeration with an oxygen-containing gas is performed. The start time of the aeration of the oxygen-containing gas is not particularly limited, and it is preferable to start the aeration of the oxygen-containing gas after introducing any one of the phenolic compound, the aromatic solvent, and the catalyst into the reactor during the preparation of the polymerization solution.

The oxygen-containing gas is not particularly limited, and specifically, a gas obtained by mixing oxygen with an arbitrary inert gas; air; a gas obtained by mixing air with an optional inert gas. The inert gas is not particularly limited, and specifically, any inert gas can be used as long as it does not largely affect the polymerization reaction. A representative inert gas is nitrogen.

The aeration rate of the oxygen-containing gas in the polymerization step is preferably 3N L/min to 14N L/min, and more preferably 6N L/min to 13N L/min, based on 1kg of the phenolic compound to be fed to the polymerization reaction, from the viewpoint of more efficient polymerization.

In the production method of the present embodiment, the polymerization method of PPE is not particularly limited. Examples of the polymerization method of the PPE include: a method of oxidatively polymerizing 2, 6-xylenol using a complex of a cuprous salt and an amine described in U.S. Pat. No. 3306874 as a catalyst; and methods described in, for example, U.S. Pat. No. 3306875, U.S. Pat. No. 3257357, U.S. Pat. No. 3257358, Japanese patent publication No. 52-17880, Japanese patent application laid-open No. 50-51197, and Japanese patent application laid-open No. 63-152628.

Examples of the polymerization method of PPE in the present embodiment include precipitation polymerization method and solution polymerization method. The production method of the present embodiment is preferably a production method in which PPE obtained by a solution polymerization method is precipitated. The solution polymerization method is a polymerization method in which polymerization is carried out in a good solvent for PPE and precipitates are not precipitated during the polymerization. In the solution polymerization method, all PPE molecules are dissolved, and the molecular weight distribution tends to be broad.

After the polymerization step, a catalyst extraction step may be provided, in which a chelating agent solution is added to the PPE mixture, the metal catalyst is extracted to the chelating agent solution side, the solution is separated into an aromatic solvent phase and a chelating agent solution phase, and the metal catalyst in the PPE mixture is removed. In the catalyst extraction step, water may be further added to the PPE mixed solution to which the chelating agent solution is added and which is subjected to liquid-liquid separation, and the liquid-liquid separation may be repeated to further extract the catalyst. In the present specification, the PPE mixed solution after the catalyst extraction in the catalyst extraction step is sometimes referred to as a "polyphenylene ether mixed solution" or a "PPE mixed solution".

In the catalyst extraction step, the metal catalyst used as the catalyst is extracted to the chelating agent solution side by adding a chelating agent solution to the PPE mixture solution after the polymerization step and stirring, and the metal catalyst in the PPE mixture solution can be removed by liquid-liquid separation of the polyphenylene ether mixture solution and the chelating agent solution.

Examples of the chelating agent used in the chelating agent solution include: acids such as hydrochloric acid and acetic acid; ethylenediaminetetraacetic acid (EDTA) and salts thereof; nitrilotriacetic acid and salts thereof; and so on. The chelating agent may be added as a simple substance, but is preferably added as an aqueous chelating agent solution or the like after being dissolved in a solvent such as water having a low dissolving ability for PPE and being phase-separated from an aromatic solvent which is a good solvent for PPE. In the case of using an aqueous chelate solution, the metal catalyst deactivated by binding to the chelating agent is extracted into the aqueous phase, and thus the PPE and the metal catalyst contained in the organic phase can be separated.

In the catalyst extraction step, the step of further adding water to the PPE mixture solution after the chelating agent solution is added and the liquid-liquid separation is performed to further extract the metal catalyst may be repeated.

The two-phase separation in the catalyst extraction step and the washing step described later may be performed by standing separation, or a liquid-liquid separator may be used.

After the polymerization step or after the catalyst extraction step, a concentration step may be provided in which the concentration of PPE in the PPE mixed solution after the polymerization step is adjusted by evaporating a part of the good solvent. In the present specification, a PPE mixed solution obtained by concentrating PPE in the concentration step is sometimes referred to as a "polyphenylene ether mixed solution" or a "PPE mixed solution". One or two of the catalyst extraction step and the concentration step may be provided.

The PPE concentration in the concentrated PPE mixture is preferably more than 30 mass%, and preferably 50 mass% or less. The PPE concentration in the PPE mixed solution is more preferably 48% by mass or less, and still more preferably 45% by mass or less.

If the PPE concentration in the PPE mixed solution is 30% by mass or less, the dispersion of the PPE mixed solution in the precipitation tank becomes too high, and the amount of fine powder increases, which is not preferable. When the PPE concentration in the PPE mixed solution exceeds 50 mass%, the dispersibility of the PPE mixed solution in the precipitation tank is lowered, and the poorly dispersed PPE mixed solution adheres to the wall surface, the stirring shaft baffle, and the like, resulting in scale formation. Further, the viscosity of the liquid is increased, and the cost of equipment for peripheral equipment such as a pump is increased, which is not preferable.

(precipitation step)

The production method of the present embodiment includes a precipitation step of mixing the PPE mixture after the polymerization step, after the catalyst extraction step, or after the concentration step with a poor solvent for PPE such as methanol and water to solid-solidify the mixture and obtain a slurry containing PPE particles. Examples of the deposition step include the following steps: optionally concentrating, adding a poor solvent for PPE such as ketones having 1 to 10 carbon atoms and alcohols having 1 to 10 carbon atoms and water to the PPE mixture, and mixing to precipitate PPE, thereby obtaining a slurry containing PPE particles.

According to the production method of the present embodiment, the poor solvent for PPE and water are added through separate pipes, and therefore the occurrence and growth of fouling after production can be suppressed. In addition, the time for the generation of the intermediate product is shortened after the change of the product, whereby the generation of the intermediate product can be suppressed, the generation of the fine particle PPE can be suppressed, and the generation of the fouling can be suppressed.

(poor solvent for PPE)

Examples of the poor solvent for the PPE include polar solvents such as ketones having 1 to 10 carbon atoms and alcohols having 1 to 10 carbon atoms. Examples of the polar solvent include methanol, ethanol, propanol, isopropanol, n-butanol, 2-butanol, pentanol, hexanol, ethylene glycol, acetone, and methyl ethyl ketone. Among them, methanol, ethanol, isopropanol, n-butanol, 2-butanol, acetone, and methyl ethyl ketone are preferable. In addition, the polar solvent is preferably an alcohol having 1 to 10 carbon atoms.

The polar solvents may be used alone, or 2 or more of them may be used in combination.

In the precipitation step, the amount of water added is 0.05 to 30% by mass, preferably 1 to 25% by mass, and more preferably 3 to 20% by mass, based on 100% by mass of the poor solvent for PPE, from the viewpoint of further suppressing the generation of transient products during the change of the type and further suppressing the generation of fine-particle PPE.

When the amount of water added is 30% by mass or less, the particle size of the obtained PPE is difficult to be increased.

Next, the precipitation tank used in the precipitation step will be described.

In the precipitation step, a precipitation tank equipped with a stirrer was used. Here, the stirrer is preferably a stirrer having at least one stage of stirring paddle selected from a group consisting of a pitched blade disc paddle, a propeller, and a ribbon paddle inside the precipitation tank. In addition, from the viewpoint of improving the mixing property, it is preferable to provide at least one baffle, and the stirring paddle is discharged downward.

Fig. 1 and 2 show an example of a precipitation tank used in the manufacturing method of the present embodiment.

The precipitation tank 1 includes, for example, a draft tube 2 in which at least one stirring blade 3 selected from a pitched blade disc blade, a propeller, and a ribbon blade is provided in the draft tube 2, and 1 or more baffle plates 4 (4 in fig. 1 and 2) are provided outside the draft tube 2.

The guide cylinder 2 is a partition wall provided in the precipitation tank 1, and examples of the shape thereof include a substantially cylindrical shape and a substantially polygonal prism shape. The guide shell 2 is preferably arranged concentrically to the precipitation tank 1.

When the paddle 3 is a diagonal disc paddle, a normal paddle is preferably tilted by 5 to 85 degrees with respect to the rotation direction, and more preferably tilted by 35 to 55 degrees. When the paddle 3 is a propeller, it is preferably a paddle having the same shape as a propeller used in a ship or the like. When the paddle 3 is a helical paddle, it is preferably a single-blade type or double-blade type helical paddle.

The baffle 4 is a baffle plate fixed to the guide cylinder 2 to control the flow. In the precipitation tank, the mixed liquid of PPE, the poor solvent of PPE, and water flows toward the bottom of the tank or the liquid surface 8 while rotating in the guide cylinder 2 with the rotation of the stirring paddle 3, and then flows almost vertically toward the liquid surface 8 or the bottom of the tank between the guide cylinder 2 and the wall of the precipitation tank 1, and circulates inside and outside the guide cylinder 2. The direction of the circulation flow of the mixed liquid is determined by the rotation direction of the paddle 3, the shape of the paddle 3, and the like. In the production method of the present embodiment, the circulating flow is preferably a circulating flow that flows toward the bottom of the tank while rotating in the guide cylinder 2 and flows almost perpendicularly to the liquid surface 8 between the guide cylinder 2 and the wall of the precipitation tank 1. In the manufacturing method of the present embodiment, for example, a lower discharge paddle for forming a flow toward the bottom of the tank may be provided in the guide cylinder 2, and a ribbon paddle for forming an upper discharge toward the flow of the liquid surface 8 may be provided outside the guide cylinder.

In the production method of the present embodiment, the poor solvent for PPE and water are fed to the precipitation tank through separate pipes. Among them, the PPE mixture, the poor solvent for PPE, and water are preferably added to the precipitation tank through different pipes.

The PPE mixed solution is fed into the precipitation tank 1 through the PPE mixed solution feed port 5. The PPE mixture liquid-feeding port 5 is preferably provided above the liquid surface 8 so as to be dropped into the precipitation tank 1. From the viewpoint of further suppressing the occurrence of fouling, the PPE mixture is preferably added dropwise to a portion that flows toward the bottom of the tank during the circulation flow.

A poor solvent for PPE is fed into the precipitation tank 1 through the poor solvent supply port 6. The poor solvent supply port 6 is preferably provided directly in the deposition tank wall above the liquid surface 8, or above the liquid surface 8 between the guide cylinder 2 and the deposition tank wall.

Water is added into the precipitation tank 1 through the water supply port 7. Since the poor solvent for water and PPE is not mixed before being added to the precipitation tank, the generation of transient products during the change of the product type can be further suppressed, the generation of fine-particle PPE can be further suppressed, and the generation of fouling can be further suppressed. The water supply port 7 is preferably provided directly above the precipitation tank wall above the liquid surface 8, or above the liquid surface 8 between the guide shell 2 and the precipitation tank wall.

The poor solvent supply port 6, the water supply port 7, and the PPE mixture supply port 5 are preferably provided so that, for example, the poor solvent, water, and the PPE mixture of PPE are sequentially added during circulation. For example, in the case of a circulation flow in which the poor solvent supply port 6, the water supply port 7, and the PPE mixture supply port 5 are provided in this order from the upstream to the downstream of the circulation flow, and the poor solvent flows toward the bottom of the tank while rotating in the draft tube, and flows substantially perpendicularly to the liquid surface between the draft tube and the wall of the precipitation tank, the poor solvent supply port 6, the water supply port 7, and the PPE mixture supply port 5 are preferably provided in this order from the wall of the precipitation tank toward the center of the precipitation tank and above the liquid surface 8.

The slurry solution can be discharged and recovered from the discharge port 9.

From the viewpoint of reducing the variety change time, the residence time of the precipitation tank is preferably 0.2 to 2 minutes, more preferably 0.5 to 1.7 minutes.

In the precipitation step, the amount of the poor solvent for polyphenylene ether added is preferably 0.3 to 2.0, more preferably 0.5 to 2.0, with respect to the mass of the good solvent for polyphenylene ether contained in the polyphenylene ether mixture added (mass of the poor solvent for polyphenylene ether added/mass of the good solvent for polyphenylene ether contained in the polyphenylene ether mixture added), from the viewpoints of further suppressing the generation of transient products at the time of change of the product, further suppressing the generation of fine-particle PPE, and further suppressing the generation of scale.

The temperature of the PPE mixed liquid immediately before addition to the precipitation tank is preferably 60 ℃ to 100 ℃. The temperature of the PPE mixed solution is more preferably 90 ℃ or lower, still more preferably 80 ℃ or lower. Further, it is more preferably 65 ℃ or higher.

When the temperature of the PPE mixed solution is less than 60 ℃, the dispersibility of the PPE mixed solution in the precipitation tank is lowered, and the PPE mixed solution having poor dispersibility adheres to the wall surface, the stirring shaft, the baffle plate, and the like, so that scale is easily formed. Further, the viscosity of the liquid is increased, which is not preferable because the cost of the peripheral equipment such as a pump is increased. When the temperature of the PPE mixed solution exceeds 100 ℃, the dispersibility of the PPE mixed solution in the precipitation tank becomes too high, and the amount of fine powder increases, which is not preferable.

The stirring speed of the precipitation tank is preferably 500 to 3000 rpm.

In addition, the amount of the solution added to the precipitation tank per unit time is preferably the same as the amount of the solution discharged from the precipitation tank per unit time.

The volume of the liquid retained in the precipitation tank may be 500m L to 3k L, and the production method of the present embodiment can be applied to the production of PPE in a wide range of scale.

From the viewpoint of the quality of the PPE to be produced, the content (fine powder ratio) of polyphenylene ether particles having a particle diameter of 105 μm or less in the polyphenylene ether particulate matter contained in the slurry liquid is preferably 11% by mass or less, more preferably 10.5% by mass or less, and still more preferably 10.0% by mass or less.

The fine powder ratio can be measured by the method described in the examples below.

In the production method of the present embodiment, the amount of transient products generated during the change of the PPE can be greatly reduced, and the PPE after the change of the PPE can be stably produced in a short time. Specifically, for example, PPE having a fine powder content of 11 mass% or less can be produced by substitution at 8 to 11 after the variety change.

In the present specification, the substitution 1 after the variety change means that, after the variety change, a solution having a volume of a liquid capable of staying in the precipitation tank is added to replace the contents in the precipitation tank. Specifically, when the retention time was 1.9 minutes, the time required for 1 substitution after the variety change was 1.9 minutes, and the time required for 2 substitutions after the variety change was 3.8 minutes.

The slurry containing the PPE particles after the deposition step is in a slurry (suspension) state in which the PPE particles are present in a mixed solution containing an aromatic solvent as a good solvent and a polar solvent as a poor solvent. In the production method of the present embodiment, for example, a solid-liquid separation step is provided after the precipitation step, and the slurry liquid after precipitation is subjected to solid-liquid separation, whereby wet PPE particles can be obtained from the slurry liquid.

The device to be used for the solid-liquid separation is not particularly limited, and a centrifuge (vibration type, screw type, sedimentation type, basket type, etc.), a vacuum filter (rotary drum type filter, belt filter, rotary drum type vacuum filter, single chamber rotary drum vacuum filter (Young filter), buchner funnel, etc.), a filter press, a roll press, etc. can be used.

The wet PPE particles separated in the solid-liquid separation step are impregnated with a large amount of a good solvent component such as an aromatic solvent. In the production method of the present embodiment, for example, a washing step may be provided after the solid-liquid separation step, and the step of washing the wet PPE particles with a washing liquid containing a good solvent containing at least the aromatic solvent and a poor solvent containing at least the polar solvent and performing solid-liquid separation may be repeated to obtain the PPE particles. The content of the good solvent component contained in the wet PPE particles can be reduced by washing the wet PPE particles with a washing liquid containing an aromatic solvent and a polar solvent.

After the above washing step, the slurry liquid can be separated into the solvent and the wet PPE particles by a solid-liquid separation step. In this case, the step of washing the wet PPE particles with a poor solvent and separating the solid from the liquid may be repeated.

The obtained wet PPE particles can be pulverized by a pulverizer, and the fine powder ratio can be adjusted. Examples of the pulverizer include a jaw crusher, a cone crusher, a hammer crusher, a screen crusher, a ball mill, a high-speed rotary mill, and a jet mill.

In the production method of the present embodiment, for example, a drying step may be provided after the washing step or the solid-liquid separation step to dry the PPE particles.

The drying step may be performed after the pulverization, or may be performed without the pulverization.

The drying temperature is preferably 60 ℃ or higher, more preferably 80 ℃ or higher, further preferably 120 ℃ or higher, further preferably 140 ℃ or higher, and particularly preferably 150 ℃ or higher. When the drying temperature is less than 60 ℃, the content of a good solvent for PPE, such as aromatic hydrocarbon in PPE, may not be efficiently suppressed to less than 1.5 mass%.

In order to increase the yield of PPE after the drying step, a method of increasing the drying temperature, a method of introducing an inert gas such as nitrogen into the PPE during drying, a method of increasing the degree of vacuum during drying, a method of stirring the PPE during drying, and the like are preferable.

In the drying step, a dryer having a mixing function is preferably used. Examples of the mixing function include a stirring type and a rotary type dryer. This can increase the throughput and maintain high productivity.

The PPE obtained by the production method of the present embodiment will be described in detail below.

[ polyphenylene ether ]

The PPE obtained by the production method of the present embodiment is a homopolymer and/or a copolymer including a repeating unit structure represented by the following general formula (2).

In the present specification, the PPE obtained by the production method of the present embodiment may be referred to as a PPE of the present embodiment.

[ CHEM 2]

In the formula (2), R₁、R₂、R₃And R₄Each independently selected from the group consisting of an alkyl group having 1 to 7 hydrogen atoms, halogen atoms, carbon atoms, phenyl group, haloalkyl group, aminoalkyl group, hydrocarbonoxy group, and a halogen atom spaced from an oxygen atom by at leastA halohydrocarbyloxy group of 2 carbon atoms.

The homopolymer of the PPE is not particularly limited, and specific examples thereof include 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-ethyl-6-n-propyl-1, 4-phenylene) ether, poly (2-ethyl-, Poly (2-methyl-6-chloroethyl-1, 4-phenylene) ether, and the like. Among them, poly (2, 6-dimethyl-1, 4-phenylene) ether is preferable from the viewpoint of low cost of raw materials and easy availability.

The copolymer of PPE is not particularly limited, and specific examples thereof include a copolymer of 2, 6-dimethylphenol and 2,3, 6-trimethylphenol, a copolymer of 2, 6-dimethylphenol and o-cresol, a copolymer of 2, 6-dimethylphenol, 2,3, 6-trimethylphenol and o-cresol, and the like. Among them, a copolymer of 2, 6-dimethylphenol and 2,3, 6-trimethylphenol is preferable from the viewpoint of low cost of raw materials and easy availability.

The reduced viscosity of the PPE of this embodiment as measured at 30 ℃ using a 0.5g/d L chloroform solution is preferably 0.25d L/g to 0.70d L/g, more preferably 0.25d L/g to 0.60d L/g.

When the reduced viscosity is less than 0.25d L/g, the dispersibility of the PPE good solvent solution in the precipitation tank becomes too high, and hence fine particles increase, which is not preferable, and sufficient mechanical properties cannot be exhibited, and when the reduced viscosity is more than 0.70d L/g, the dispersibility of the PPE good solvent solution in the precipitation tank decreases, the PPE good solvent solution having poor dispersibility adheres to wall surfaces, stirring shaft baffles, etc., and forms scales.

The reduced viscosity was determined by preparing a chloroform solution of PPE at 0.5g/d L, using a Ubbelohde viscometer at 30 ℃ using this chloroform solution as a sampleReduced viscosity η_sp/c(dL/g)。

The content (fine powder ratio) of polyphenylene ether particles having a particle diameter of 105 μm or less in the polyphenylene ether particulate matter in the slurry liquid obtained by the production method of the present embodiment is preferably 35% by mass or less, more preferably 30% by mass or less, further preferably 11% by mass or less, further preferably 10.5% by mass or less, and particularly preferably 10% by mass or less.

The average particle diameter of the PPE in the present embodiment is preferably 250 μm or more, more preferably 280 μm or more.

The average particle size of PPE can be measured as a volume average particle size by a wet method (methanol solvent) using a laser diffraction scattering particle size distribution measuring apparatus manufactured by shimadzu corporation as a laser diffraction scattering particle size distribution meter.

The diameter (median diameter) of the particles corresponding to the median cumulative value can be regarded as the average particle diameter (μm) from the cumulative curve of the particle diameter distribution of the volume average particle diameter. Similarly, the content (mass%) of particles having a particle diameter of 105 μm or less in the powder obtained from the cumulative curve of the particle diameter distribution of the volume average particle diameter can be calculated as the fine powder ratio.

Examples

The present embodiment will be specifically described below by way of examples and comparative examples, but the scope of the present embodiment is not limited to these examples.

First, measurement methods of physical properties, characteristics, and the like applied to examples and comparative examples are shown below.

(1) PPE concentration in PPE mixtures

The PPE mixture after the solution polymerization or after the concentration step was weighed into an aluminum pan and dried at room temperature for 60 minutes. The sample whose surface was in a dry state was placed in a vacuum dryer together with an aluminum pan, the temperature of the vacuum dryer was set to 180 ℃, and the pressure was reduced to 10torr, and vacuum drying was performed for 120 minutes in this state. The PPE concentration (% by mass) in the PPE mixture was calculated from the amount of the sample before and after drying.

(2) Reduced viscosity

A reduced viscosity (η sp/c) [ d L/g ] was determined at 30 ℃ using a Ubbelohde viscosity tube for a chloroform solution of 0.5g/d L.

(3) State of scale deposition

In the production of the slurry, the scale formation after about 20 minutes of change in the type was visually observed, and the evaluation was performed according to the following criteria.

○, the scale is not adhered to the surface of the steel plate, and the scale does not grow.

△, the scale adhered and grown but was in a state in which the operation could be continued.

× PPE is wound around the stirring shaft, and the stirring shaft forms large blocks which fall off during operation and are broken by stirring and mixed into the product.

(4) Rate of fine powder

From the obtained slurry, the content of particles having a particle diameter of 105 μm or less, which is obtained from the cumulative curve of the particle diameter distribution of the volume average particle diameter, among the PPE particles contained in the slurry solution, was calculated as the fine powder ratio (% by mass) using a laser diffraction particle size distribution measuring apparatus (model SA L D-3100, manufactured by shimadzu corporation).

< production example 1>

In a 40-liter jacketed polymerization vessel equipped with a shower head for introducing an oxygen-containing gas, a turbine impeller, and a baffle at the bottom and a reflux condenser on an exhaust line at the upper part of the polymerization vessel, 4.57g of divalent copper oxide, 24.18g of a 47 mass% aqueous hydrogen bromide solution, 11.00g of di-t-butylethylenediamine, 62.72g of di-n-butylamine, 149.92g of butyldimethylamine, 20.65kg of toluene, and 3.12kg of 2, 6-dimethylphenol were added while blowing nitrogen at a flow rate of 0.5L/min, and the mixture was stirred until a uniform solution was obtained and the internal temperature of the polymerization vessel was 25 ℃.

Then, dry air was introduced into the polymerization vessel from a blow head at a rate of 32.8N L/min to initiate polymerization, and dry air was introduced for 140 minutes to obtain a polymerization mixture, wherein the internal temperature during polymerization was controlled to 40 ℃ and the polymerization solution was in a uniform solution state at the time of completion of polymerization.

The supply of dry air was stopped, and 10kg of a 2.5 mass% aqueous solution of ethylenediaminetetraacetic acid tetrasodium salt (manufactured by Homopchemistry) was added to the PPE mixture solution after polymerization. The PPE mixture was stirred at 70 ℃ for 150 minutes, thereafter, allowed to stand for 20 minutes, and the organic phase and the aqueous phase were separated by liquid-liquid separation to recover the organic phase. The PPE concentration in the obtained PPE polymerization liquid was 13.1% by mass. The obtained PPE polymer liquid was used as PPE polymer liquid (1).

Using a part of the obtained PPE polymerization liquid (1), a slurry in which PPE was precipitated was prepared by adding an excessive amount of methanol and a small amount of water to room temperature. Thereafter, the slurry was filtered by a bottom discharge centrifuge (Tanabe Willtec, model 0-15). After filtration, excess methanol and a small amount of water were added to the bottom discharge centrifuge and filtered again to give wet PPE particles.

Next, the wet PPE pellets were placed in a vacuum dryer and held at 150 ℃ under 1mmHg for 1.5 hours to obtain polyphenylene ether pellets in a dry state, the reduced viscosity of the obtained PPE pellets was 0.502d L/g.

< production example 2>

A PPE polymer liquid was produced in the same manner as in production example 1, except that the aeration time of the dry air was changed to 90 minutes. The PPE concentration in the obtained PPE polymerization liquid was 13.1% by mass. The obtained PPE polymer liquid was used as PPE polymer liquid (2).

The reduced viscosity of the PPE polymer liquid (2) obtained in part was 0.323d L/g in a dried state, as in production example 1.

< production example 3>

A PPE polymer liquid was produced in the same manner as in production example 1, except that the aeration time of the dry air was changed to 110 minutes. The PPE concentration in the obtained PPE polymerization liquid was 13.1% by mass. The obtained PPE polymer liquid was used as PPE polymer liquid (3).

The reduced viscosity of the PPE polymer liquid (3) obtained in part was 0.404d L/g in a dried state, as in production example 1.

< production example 4>

A PPE polymer liquid was produced in the same manner as in production example 1, except that the aeration time of the dry air was changed to 180 minutes. The PPE concentration in the obtained PPE polymerization liquid was 13.1% by mass. The obtained PPE polymer liquid was used as PPE polymer liquid (4).

The reduced viscosity of the PPE polymer liquid (4) obtained in part was 0.609d L/g in a dried state, as in production example 1.

[ example 1]

The PPE polymerization solution (1) obtained in production example 1 was charged into a jacketed stirring tank 1, and a heating medium of 120 ℃ was passed through the jacket to heat it. The generated steam containing toluene as a main component was cooled by a condenser, and the condensed toluene was taken out of the system and concentrated until the polymer concentration in the stirred tank became 35 mass%. This operation was repeated to prepare 10Kg of a PPE mixed solution (1) having a polymer concentration of 35 mass%. Similarly, 10Kg of PPE mixed solution (2) having a polymer concentration of 35 mass% was prepared by charging PPE polymerization solution (2) obtained in preparation example 2 into a jacketed stirring tank 2.

In the precipitation step, the mixed solution is continuously supplied from the stirring tank (see FIG. 1 and FIG. 2) to the precipitation tank by using a jacketed precipitation tank equipped with a draft tube equipped with 4 baffles and 4-blade inclined-blade disc paddles, the capacity of the liquid staying in the precipitation tank is 1232m L, 500g of toluene and 500g of methanol are charged into the precipitation tank, and stirring is performed at 1700rpm, an overflow line is provided in the stirring tank, and when the amount of the liquid exceeds 1232m L, the mixed solution overflows and is discharged to the outside of the tank, the circulating flow is such that the mixed solution flows to the bottom of the tank while rotating within the draft tube, the mixed solution flows to the liquid surface almost vertically between the draft tube and the precipitation tank, and the position of the feed line, a PPE mixed solution supply port is provided within the draft tube above the liquid surface, such that the mixed solution is added to a portion of the tank during circulation, the mixed solution supply port and a water supply port are provided above the tank, the mixed solution supply port is changed from the mixed solution supply tank to the inside of the draft tube and the precipitation tank by a stirring tank (1 g of PPE) after dropping the poor solvent is added to the precipitation tank, the stirring tank, the mixed solution is changed to the stirring tank by a stirring tank (see FIG. 1g of PPE), and a stirring tank), the stirring tank by a stirring tank, a stirring tank (see FIG. 2g of a stirring tank), a stirring tank is carried out nozzle is carried out by adding nozzle, a stirring nozzle is carried out by adding a stirring nozzle, a stirring.

After the substitution of the

cultivar change

1, 2,3 and about 20 minutes, the slurry was collected and a part of each slurry was filtered by a bottom discharge centrifuge (Tanabe Willtec, 0to 15). After filtration, excess methanol and a small amount of water were added to the bottom discharge centrifuge and filtered again to give wet PPE particles. Next, the wet PPE pellets were charged into a vacuum dryer and held at 150 ℃ under 1mmHg for 1.5 hours, and the reduced viscosity of the obtained polyphenylene ether pellets in a dried state was measured, and as a result, almost the same measured values were obtained in the respective slurry liquids, and polyphenylene ethers could be stably produced even after the varieties were changed. From the beginning, the PPE mixed liquid (2) was added to the precipitation tank at 386 g/min through the first nozzle, methanol was added to the precipitation tank at 239 g/min through the second nozzle, and water was added to the precipitation tank at 15 g/min through the third nozzle, and the reduced viscosity of the polyphenylene ether pellets in a dry state was measured for the obtained slurry liquid in the same manner as described above.

Comparative example 1

The procedure of example 1 was repeated except that 2 liquid addition nozzles were provided above the liquid surface, the PPE mixed liquid (1) was added to the tank at 445 g/min by the first nozzle, the mixed solution of methanol and water was added to the tank at 203 g/min by the second nozzle, the operation was continued for about 20 minutes, the PPE mixed liquid (2) was added to the tank at 386 g/min by the first nozzle, and the mixed solution of methanol and water was added to the tank at 254 g/min by the second nozzle. The slurry liquid obtained was subjected to the respective measurements by the methods described above. The results are shown in Table 1.

Further, in the same manner as in example 1, the reduced viscosity of the polyphenylene ether pellets in a dry state was measured by recovering the slurry liquid after the substitution of the species change 1, after the substitution 2, after the substitution 3, and after about 20 minutes, and almost the same measured values were obtained. From the beginning, it was confirmed that the reduced viscosity of the PPE pellets in a dry state was almost the same as that of the resulting slurry liquid by adding the PPE mixed liquid (2) at 386 g/min through the first nozzle and adding the methanol/water mixed liquid at 254 g/min through the second nozzle.

[ example 2]

The PPE polymerization solution (3) obtained in production example 3 was charged into the stirring vessel 1 with a jacket, and a heating medium of 120 ℃ was passed through the jacket to heat the solution. The generated steam containing toluene as a main component was cooled by a condenser, and the condensed toluene was taken out of the system and concentrated until the polymer concentration in the stirred tank became 40 mass%. This operation was repeated to prepare 10Kg of a PPE mixed solution (3) having a polymer concentration of 40 mass%. Similarly, 10Kg of PPE mixed solution (4) having a polymer concentration of 40 mass% was prepared by charging the PPE polymerization solution (4) obtained in preparation example 4 into the jacketed stirring tank 2.

PPE mixture (3) was added to the vessel through the first nozzle at 541 g/min, methanol was added to the vessel through the second nozzle at 535 g/min, and water was added to the vessel through the third nozzle at 27 g/min, i.e., the temperature immediately before PPE mixture (3) was added was 75 ℃. After the continuous operation for about 20 minutes, the flask was changed from the stirring vessel 1 to the stirring vessel 2, the PPE mixed liquid (4) was added to the vessel through the first nozzle at 595 g/min, methanol was added to the vessel through the second nozzle at 482 g/min, and water was added to the vessel through the third nozzle at 26 g/min, whereby the variety of the PPE was changed. The temperature immediately before the addition of PPE in mixture (4) was 75 ℃. Otherwise, the same procedure as in example 1 was repeated. The slurry liquid obtained was subjected to the respective measurements by the methods described above. The results are shown in Table 1.

Further, in the same manner as in example 1, the reduced viscosity of the polyphenylene ether pellets in a dry state was measured by recovering the slurry liquid after the substitution of the species change 1, after the substitution 2, after the substitution 3, and after about 20 minutes, and almost the same measured values were obtained. From the beginning, the PPE mixed solution (4) was added from the first nozzle at 595 g/min, methanol was added from the second nozzle at 482 g/min, and water was added from the third nozzle at 26 g/min, and it was confirmed that the reduced viscosity was almost equal to that of the resulting slurry liquid in the dried state.

Comparative example 2

The procedure of example 2 was repeated except that liquid addition nozzles were provided at 2 positions above the liquid surface, the PPE mixed liquid (3) was added to the vessel at 541 g/min through the first nozzle, the mixed solution of methanol and water was added to the vessel at 562 g/min through the second nozzle, the operation was continued for about 20 minutes, the PPE mixed liquid (4) was added to the vessel at 595 g/min through the first nozzle, and the mixed solution of methanol and water was added to the vessel at 508 g/min through the second nozzle. The slurry liquid obtained was subjected to the respective measurements by the methods described above. The results are shown in Table 1.

Further, in the same manner as in example 1, the reduced viscosity of the polyphenylene ether pellets in a dry state was measured by recovering the slurry liquid after the substitution of the species change 1, after the substitution 2, after the substitution 3, and after about 20 minutes, and almost the same measured values were obtained. From the beginning, it was confirmed that the reduced viscosity of the PPE pellets in a dry state was almost the same as that of the resulting slurry liquid by adding the PPE mixed solution (4) at 595 g/min through the first nozzle and adding the methanol/water mixed solution at 508 g/min through the second nozzle.

[ TABLE 1]

Industrial applicability

The polyphenylene ether obtained by the production method of the present invention has industrial applicability as materials for automobile parts, heat-resistant parts, parts for electronic devices, industrial parts, coating agents, insulating coatings, and the like.

Claims

1. A method for producing a polyphenylene ether, characterized by comprising the steps of:

a concentration step of adjusting the polyphenylene ether concentration of the polyphenylene ether mixed solution to more than 30% by mass and 50% by mass or less; and

a precipitation step of adding the polyphenylene ether mixed solution, a poor solvent for polyphenylene ether, and water to a precipitation tank having at least one stirring blade selected from the group consisting of a pitched blade disc blade, a propeller, and a ribbon blade inside the precipitation tank, and mixing them under rotational stirring to precipitate polyphenylene ether to obtain a slurry liquid containing polyphenylene ether particles,

in the precipitation step, the poor solvent for the polyphenylene ether and the water are added to the precipitation tank through different supply ports,

in the precipitation step, the amount of water added is 0.05 to 30% by mass relative to 100% by mass of the poor solvent for the polyphenylene ether.

2. The method for producing a polyphenylene ether according to claim 1, wherein in the precipitation step, a ratio of a mass of the poor solvent for the polyphenylene ether to be added to a mass of the good solvent for the polyphenylene ether contained in the polyphenylene ether mixture solution to be added, that is, a mass of the poor solvent for the polyphenylene ether to be added/a mass of the good solvent for the polyphenylene ether contained in the polyphenylene ether mixture solution to be added is 0.3 to 2.0.

3. The method for producing a polyphenylene ether according to claim 1 or 2, wherein the phenolic compound is 2, 6-dimethylphenol.

4. The method for producing a polyphenylene ether according to claim 1 or 2, wherein the content of polyphenylene ether particles having a particle diameter of 105 μm or less in the polyphenylene ether granules is 11 mass% or less.