CN110078912B

CN110078912B - Continuous pressure filtration washing method for polyphenyl ether

Info

Publication number: CN110078912B
Application number: CN201810079557.7A
Authority: CN
Inventors: 李振刚
Original assignee: Bluestar Beijing Technology Center Co Ltd
Current assignee: Bluestar Beijing Technology Center Co Ltd
Priority date: 2018-01-26
Filing date: 2018-01-26
Publication date: 2021-11-09
Anticipated expiration: 2038-01-26
Also published as: CN110078912A

Abstract

The invention provides a preparation method of polyphenyl ether, which adopts a continuous filtering and washing process, adopts a pressurizing and filtering method in a solid-liquid separation procedure to carry out solid-liquid separation on polyphenyl ether slurry liquid to obtain polyphenyl ether filter cakes, and then carries out spray cleaning on the polyphenyl ether filter cakes in a cleaning procedure. Through the pressure filtration and the continuous non-dispersive cleaning operation, the content of the good solvent in the filter cake can be effectively reduced, and the crushing rate of the polyphenyl ether particles in the filter cake is controlled.

Description

Continuous pressure filtration washing method for polyphenyl ether

Technical Field

The invention belongs to the technical field of chemical processes, and particularly relates to a continuous pressurizing, filtering and washing method after synthesis of polyphenyl ether.

Background

The polyphenylene oxide is separated out and then needs to be filtered and washed before entering a dryer, and the process requirements are as follows: (1) the total volatile content in the filter cake is reduced to below 60 percent of the total weight of the filter cake, the good solvent (such as toluene) is reduced to below 10 percent of the total weight of the filter cake, and the excessive content of the good solvent can cause the polyphenyl ether to be adhered to the inner wall of the dryer during the drying process, thereby reducing the drying efficiency and even damaging the dryer. (2) The breakage of particles during filtering and washing is minimized, especially the particles smaller than 100 μm are controlled within 15%, and the excessive fine powder increases the possibility of dust pollution and dust explosion in downstream processing.

At present, the filtering and purifying process in the synthesis process of polyphenyl ether adopts the processes of multiple dispersion and centrifugal drying, the flow is complex, the intermediate stirring times are multiple, and the particle crushing rate is high.

JP-A-2004-531626, JP-A-2014-508208, JP-B-45-587, US6407200B1, CN1531568A mention only optimizing the precipitation process upstream of the filtration by designing the precipitation tank and changing the process conditions for the polyarylene ether precipitation process, such as: the ratio of the poor solvent (methanol, C1-C6 alcohols, etc.) to water, the ratio of the poor solvent to the good solvent, the solid phase concentration of the polyphenylene ether solution, particle control, etc., to reduce the generation of fine particles.

US6437084B1 discloses a process for the preparation of polyphenylene ether, wherein the example mentions that concentrated polyphenylene ether is precipitated as a slurry, passed through a vacuum filter and then re-slurried with methanol, separated by a centrifuge and finally separated by a dryer.

US6407200B1 discloses a process for the preparation of polyphenylene ether. In the embodiment, the solid-liquid separation adopts the same method as the patent, and polyphenylene oxide suspension is subjected to vacuum separation, then is dispersed by methanol, and is dried after being centrifugally dried.

CN1531568A discloses a method for preparing poly (arylene ether) s by removing a portion of the solvent to produce a concentrated solution having a cloud point Tcloud, which is then mixed with methanol in a high shear stirred tank to form a suspension of polyphenylene ether having a well-distributed particle size to reduce the amount of fine particles in the suspension. For the treatment of solid-liquid separation, it is mentioned in the patent that filters which can take various forms including rotary filters, continuous rotary vacuum filters, etc., but it is not mentioned how to control the toluene content and particle breakage rate in polyphenylene ether filter cakes.

CN1688632A mentions the procedure of polyphenylene ether precipitation and filtration, the particle size is controlled by controlling the ratio of toluene, methanol and water, and finally solid-liquid separation is carried out by a centrifuge, and also mentions a rotary or vacuum rotary filter. But the specific form and how to reduce the particle breakage rate is not mentioned.

CN107236124A discloses a method for precipitation filtration and washing of polyphenylene ether, which also uses a flow of filtration under reduced pressure, washing with stirring, and drying, and also causes the breakage of particles.

In summary, the process of the prior art post-treatment of polyphenylene ether is generally: solid-liquid separation (filtration), dispersing and cleaning (usually dispersing by stirring), secondary solid-liquid separation (refiltering), drying and the like. Most cases require at least: 2-3 times of solid-liquid separation (filtration), 1-2 times of dispersing and cleaning and 1-2 times of drying. The process needs more equipment, has long treatment time (dispersion time is more than 10min), low efficiency and high particle breakage rate, and is difficult to ensure that the particle breakage rate is not increased on the premise of reducing the concentration of a good solvent (such as toluene) as much as possible.

The inventors of the present invention found that one of the main causes of the excessive fine powder of polyphenylene ether in the prior art is: in the cleaning procedure, the filter cake is re-dispersed into the cleaning liquid under the condition of stirring to form suspended slurry, and the friction among particles, the stirring shaft and the blades causes the rapid increase of the crushing rate.

In addition, in order to reduce the content of the good solvent in the filter cake, the prior art often realizes the purpose by increasing the cleaning times, increasing the using amount of methanol, prolonging the cleaning time, increasing the stirring intensity and the like. The following problems are: the material treatment time is long, the efficiency is low, the crushing rate is increased, and the fine powder rate is high. Therefore, the prior art process has a contradiction between the reduction of the concentration of the good solvent (toluene) and the reduction of the content of fine particles in the polyphenylene ether.

Disclosure of Invention

The invention aims to find a new and more efficient method for post-treating polyphenylene ether, which can better control the content of a good solvent (such as toluene) in a polyphenylene ether filter cake and simultaneously reduce the breakage rate of polyphenylene ether particles.

The technical scheme of the invention is as follows:

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

a polymerization step of subjecting a phenolic compound to oxidative polymerization in a polymerization solution containing at least one aromatic solvent selected from the group consisting of benzene, toluene, xylene, and ethylbenzene, the phenolic compound, and a catalyst to obtain a polyphenylene ether mixed solution;

a precipitation step of adding at least one polar solvent selected from the group consisting of ketones having 1 to 10 carbon atoms, alcohols having 1 to 10 carbon atoms, and water to the polyphenylene ether mixed solution to precipitate the polyphenylene ether, thereby obtaining a slurry solution containing polyphenylene ether particles;

a solid-liquid separation step of performing solid-liquid separation on the slurry liquid to obtain a polyphenylene ether filter cake, wherein the separation step employs a pressure filtration method;

a cleaning step of spraying and cleaning the filter cake obtained in the solid-liquid separation step with a cleaning solution and removing the sprayed cleaning solution;

and a drying step of drying the polyphenylene ether cake.

Preferably, in the pressure filtration in the solid-liquid separation step, the pressure is 1.2 to 10bar, preferably 2 to 6bar, more preferably 2.5 to 5bar, and the pressure is increased to avoid boiling of the low-boiling solvent.

Preferably, the thickness of the polyphenylene ether filter cake is controlled to be 10-200 mm. More preferably, the polyphenylene ether cake has a thickness of 10 to 100mm, particularly preferably 10 to 50 mm. Of course, less than 10mm is possible, but from a production efficiency point of view, too low a thickness may result in a less efficient overall filtration wash. In the solid-liquid separation step, the thickness of the polyphenylene ether cake can be controlled by controlling the feed rate of the slurry liquid.

The washing step may be carried out once, twice or more, for example, 2 to 8 times, preferably 3 to 5 times.

The inventors found that by controlling the amount of the cleaning liquid, the temperature of the cleaning liquid, and the cleaning pressure, a further higher cleaning effect can be obtained.

The washing liquid is preferably used in an amount of 0.1 to 80 times, preferably 1 to 10 times, for example, 2 times, 3 times, 4 times, 5 times, 6 times, 7 times, etc. the weight of the polyphenylene ether cake.

Preferably, the temperature of the washing liquid is 30-60 deg.C, preferably 35-50 deg.C.

Preferably, the washing is carried out under pressure, at a pressure of 1.2 to 10bar, preferably 2 to 6bar, more preferably 2.5 to 5 bar.

According to the present invention, the composition of the cleaning liquid may be selected and adjusted according to the purpose of washing. For example, a poor solvent such as a polar solvent, which may be at least one polar solvent selected from the group consisting of ketones having 1 to 10 carbon atoms, alcohols having 1 to 10 carbon atoms, and water, may be used as the cleaning solution. The cleaning solution may be a mixed solvent comprising at least one aromatic solvent selected from the group consisting of benzene, toluene, xylene and ethylbenzene, and at least one polar solvent selected from the group consisting of ketones having 1 to 10 carbon atoms, alcohols having 1 to 10 carbon atoms and water.

Preferably, the polar solvent is methanol.

Preferably, the aromatic solvent is toluene.

Preferably, the mixed solvent contains 0.5 to 18.0 mass% of an aromatic solvent and 82.0 to 99.5 mass% of a polar solvent; more preferably, the content of the aromatic solvent is 3.5 to 10 mass% and the content of the polar solvent is 90 to 96.5 mass%; more preferably, the content of the aromatic solvent is 5.5 to 9.0% by mass and the content of the polar solvent is 91 to 94.5% by mass.

In one embodiment of the present invention, the cleaning liquid is methanol.

In another embodiment of the present invention, the cleaning solution is a mixed solvent of methanol and toluene. The mixed solvent contains 0.5 to 18.0 mass% of toluene and 82.0 to 99.5 mass% of methanol, more preferably contains 3.5 to 10 mass% of toluene and 90 to 96.5 mass% of methanol, and still more preferably contains 5.5 to 9.0 mass% of toluene and 91.0 to 94.5 mass% of methanol.

One advantage of the cleaning process of the present invention is that: without dispersion stirring operation, the particle breakage rate is greatly reduced.

According to the present invention, the drying process is preferably preceded by a pre-drying process, which may be performed by a conventional drying method, such as drying by gas blowing or spin drying, to remove the solvent on the surface of the filter cake. Preferably, the drying by gas purge is performed, for example, by inert gas purge, including but not limited to nitrogen purge. The temperature of the drying gas is set to be between 1 and 200 ℃. The inert gas for purging and drying can be recycled.

In the pre-drying process, an inert gas (e.g., N)₂、CO₂Ar, etc.) in an amount of 0.01 to 50Nm³Perkg of polyphenylene ether cake, preferably 0.3-10Nm³Perkg of polyphenylene ether cake, more preferably 0.5-5.0Nm³Perkg of polyphenylene ether filter cake.

According to the present invention, the solid-liquid separation step, the washing step and the preliminary drying step are carried out in a batch manner or a continuous manner, and preferably are carried out continuously and sequentially.

Preferably, the solid-liquid separation step, the washing step and the preliminary drying step are carried out in one facility unit. The equipment can be selected from a self-rotating drum type filter press, so that the processes of filtering, cleaning and pre-drying are sequentially and continuously completed in the rotating process of the rotary drum; or a rotary disc type filter is selected, so that the processes of filtering, cleaning and pre-drying are sequentially and continuously completed in the rotary disc rotating process; or a horizontal belt filter is selected, so that the processes of filtering, cleaning and pre-drying are sequentially and continuously completed along with the operation of the conveying belt.

In one embodiment of the invention, a rotary drum filter press is used.

The rotary drum filter press is a continuous type filtering apparatus known in the art. The surface of the rotary drum is provided with a filter tank which is divided into different areas by a partition board and is divided into a feeding filter area, a washing area, a pre-drying area and a discharging area according to the process requirements. The rotary drum is externally provided with a shell, and a slurry inlet, a cleaning liquid inlet, a pre-drying gas inlet and a scraper are arranged on the shell at intervals. The partition plate is mounted on the surface of the drum, or on the inner surface of the housing facing the surface of the drum. The drum rotates for one circle to complete the processes of filtering, washing, pre-drying and discharging in sequence.

In one embodiment of the invention, the slurry inlet is arranged at the lower part of the shell of the rotary drum, and the cleaning liquid inlet, the pre-drying gas inlet and the scraper are arranged on the shell at intervals in turn from the slurry inlet in the anticlockwise direction. The surface of the rotary drum is provided with a clapboard which divides a filter tank on the surface of the rotary drum into a feeding filter area, a washing area, a pre-drying area and a discharging area. The drum rotates counterclockwise. And the polyphenyl ether slurry enters the rotary drum from the slurry inlet, is spread on the surface of the filter tank, forms polyphenyl ether filter cakes on the surface of the rotary drum through pressure filtration, and adds cleaning solution to perform spray washing after the filter cakes rotate to the cleaning solution inlet along with the rotary drum. And then blowing and drying by inert gas after the drum rotates to the position of the pre-drying gas inlet. When the filter cake is rotated to the position of the scraper, the filter cake falls off from the surface of the rotary drum under the action of gravity, and the filter cake which does not fall off is scraped off by the scraper. The slurry is continuously fed in and is matched with the rotary drum to continuously rotate, so that the continuous work of filtering, cleaning, pre-drying and discharging is realized.

Because the polyphenylene oxide filter pulp is uniformly distributed into the filter tanks in the filtering process, the thickness of a filter cake in a single filter tank is reduced, and the contact with a detergent is sufficient. Therefore, the good solvent (e.g., toluene) in the cake can be quickly reduced to the index requirement. Meanwhile, filter cakes are always in a static state on the surface of the rotary drum in the processes of filtering, washing and predrying, and most of the filter cakes automatically fall off by gravity in the discharging process, so that polyphenyl ether particles are kept complete and the breakage rate is low. The rotary drum filter press is easy to scale up, the filter cake thickness can be kept unchanged after the scale-up, and therefore the feeding and washing of a single filter tank can be kept unchanged.

Preferably, pressure is provided in the drum housing such that filtration, washing and predrying are all accomplished under pressure, at a pressure of 1.2 to 10bar, preferably 2 to 6 bar.

For a rotary drum filter press, the preferred process conditions are: a pressure of 1.2 to 10bar, preferably 2 to 6 bar; the washing amount of the cleaning liquid is 0.1 to 80Kg/Kg of filter cake, preferably 1 to 10Kg/Kg of filter cake; the consumption of the pre-drying purging inert gas is 0.01-50Nm³Perkg of filter cake, preferably 0.3 to 10Nm³Perkg of filter cake. The good solvent (such as toluene) in the filter cake after filtration can be controlled below 10% of the total weight of the filter cake, and the particle breaking growth rate is less than or equal to 2.0%.

The diameter of the rotary drum filter press can be 50-500cm, and the length of the filter tank arranged on the surface of the rotary drum can be 5-300 cm.

In another embodiment of the invention, a horizontal belt filter is adopted, a filtering section, a cleaning section, a pre-drying section and a discharging section are sequentially arranged along the horizontal length direction of the filter belt, a slurry inlet is arranged above the filtering section, a cleaning solution inlet is arranged above the cleaning section, a drying gas inlet is arranged above the pre-drying section, and the discharging section is arranged at the tail end turning position of the horizontal belt. And uniformly spreading the polyphenyl ether slurry on a filter belt through a feeding hole, and forming polyphenyl ether filter cakes on the filter belt through pressure filtration. The filter cake moves to the cleaning section along with the filter belt, and the cleaning liquid is removed by negative pressure or pressurization after being sprayed onto the filter cake from the cleaning liquid inlet. The filter cake continuously moves to a pre-drying section along with the front of the filter belt, and the drying gas is sent out from the drying gas inlet to blow the filter cake to be dried. The filter cake moves to the section of unloading along with the filter belt, because the filter belt moves to gyration department, the filter cake drops from the filter belt because of gravity, and the filter cake accessible scraper blade that does not drop further scrapes. The slurry is continuously fed in and matched with the continuous loop movement of the filter belt, so that the continuous work of filtering, cleaning, pre-drying and discharging is realized.

Preferably, the whole set of horizontal belt filters is placed in a closed housing, and pressure is provided in the housing so that filtration, washing and predrying are all accomplished under pressure, the pressure being 1.2-10bar, preferably 2-6 bar.

According to the invention, the cleaning process preferably adopts countercurrent washing, namely n-level or n-time washing, the cleaning solution after the n-level (time) washing is collected and stored in an nth-level (time) cleaning solution storage container and sent to an n-1-level (time) cleaning section for spray washing, meanwhile, the cleaning solution after the n-1-level (time) washing is collected and stored in an n-1-level (time) cleaning solution storage container and sent to an n-2-level (time) cleaning section for spray washing, and the like until the 1-level washing. Therefore, the content of the good solvent (such as toluene) in the filter cake can be stably reduced to below 10 percent without increasing the consumption of fresh cleaning liquid.

In one embodiment of the invention, 2 to 8 or 2 to 8 stages of counter-current washing are employed, more preferably 3 to 5 or 3 to 5 stages of counter-current washing.

According to the present invention, the polymerization step may be followed by a catalyst removal step of adding a chelating agent solution to the polyphenylene ether mixed solution, extracting the metal catalyst to the chelating agent solution side, and separating the liquid from the liquid into an aromatic solvent phase and a chelating agent solution phase to remove the metal catalyst in the polyphenylene ether mixed solution. In the catalyst removal step, water may be further added to the polyphenylene ether 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 remove the catalyst.

After the polymerization step or after the catalyst removal step, a concentration step of separating the good solvent from the polyphenylene ether mixed solution and concentrating the polyphenylene ether may be provided.

The polyphenylene ether obtained by the production method of the present invention will be described in detail below.

Polyphenylene Ether (PPE)

The polyphenylene ether produced by the production method of the present invention is a homopolymer and/or copolymer comprising a repeating unit structure represented by the following general formula (1).

In the formula (1), R₁、R₂、R₃And R₄Each independently is any one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 7 carbon atoms, a phenyl group, a haloalkyl group, an aminoalkyl group, a hydrocarbonoxy group, and a halohydrocarbonoxy group in which the halogen atom is separated from the oxygen atom by at least 2 carbon atoms.

In the above formula (1), R is₁、R₂、R₃And R₄Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom and the like, and a chlorine atom and a bromine atom are preferable.

In the above formula (1), R is₁、R₂、R₃And R₄The alkyl group is preferably a linear or branched alkyl group having 1 to 6 carbon atoms, and more preferably a linear or branched alkyl group having 1 to 3 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group. Among them, methyl and ethyl are preferable, and methyl is more preferable.

In the above formula (1), R₁、R₂、R₃And R₄The alkyl group represented may have 1 or 2 or more substituents at substitutable positions.

Examples of such a substituent include a halogen atom (e.g., a fluorine atom, a chlorine atom, and a bromine atom), an alkyl group having 1 to 6 carbon atoms (e.g., a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and a hexyl group), an aryl group (e.g., a phenyl group and a naphthyl group), an alkenyl group (e.g., a vinyl group, a 1-propenyl group, and a 2-propenyl group), an alkynyl group (e.g., an ethynyl group, a 1-propynyl group, and a 2-propynyl group), an aralkyl group (e.g., a benzyl group and a phenethyl group), and an alkoxy group (e.g., a methoxy group and an ethoxy group).

The homopolymer of the polyphenylene ether 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-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 the polyphenylene ether 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 molecular weight of polyphenylene ether can be measured by a gel permeation chromatography measuring apparatus.

In the polyphenylene ether produced by the production method of the present invention, the content of the polyphenylene ether component having a molecular weight of 500 or less is preferably 0.8% by mass or less, more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less. Examples of the polyphenylene ether component having a molecular weight of 500 or less include dimers, trimers, and oligomers of the above phenol compound. The content of the polyphenylene ether component having a molecular weight of 500 or less can be adjusted by the composition of the polymerization solution, the conditions of the polymerization step, the composition of the cleaning liquid, the conditions of the cleaning step, and the like.

The polyphenylene ether produced by the production method of the present invention preferably has a small amount of residual metal derived from a metal catalyst or the like used in polymerization. Specifically, the concentration of the residual metal in the polyphenylene ether produced by the production method of the present invention is preferably 1.0 mass ppm or less, more preferably 0.8 mass ppm or less, and still more preferably 0.6 mass ppm or less, from the viewpoint of improving the heat aging property. The residual metal can be adjusted by, for example, the conditions of the catalyst removal step, the composition of the cleaning liquid, the conditions of the cleaning step, and the like.

The polyphenylene ether produced by the production method of the present invention preferably has a small amount of solvent remaining therein, preferably less than 1.5% by mass, more preferably 0.5% by mass or less, and still more preferably 0.3% by mass or less. The residual volatile components can be adjusted, for example, by the composition of the cleaning liquid, the conditions of the cleaning step, and the like.

The respective steps in the method for producing a polyphenylene ether of the present invention will be described in detail below.

< polymerization step >

Phenolic compounds

Examples of the phenol 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-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, and, 2-methyl-6-methylphenol, 2, 6-dimethylphenol, 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-isopropylphenol, 2-methyl-5-n-propylphenol, 2-methyl-5-n-butylphenol, 2, 5-di-n-propylphenol, 2-ethyl-5-chlorophenol, 2-allyl-5-methylphenol, 2-allyl-5-n-butylphenol, 2, 5-di-n-propylphenol, 2-ethyl-5-chlorophenol, 2-methyl-5-n-butylphenol, 2, 5-di-n-propylphenol, 2, 5-methylphenol, 2, 5-dimethylphenol, 2, 5-di-propylphenol, 2, 5-dimethylphenol, 2, 5-methyl-propylphenol, 2, and 2, 2-methyl-5-phenylphenol, 2, 5-diphenylphenol, 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 and the like.

For reasons of low cost and easy availability, 2, 6-dimethylphenol, 2, 6-diethylphenol, 2, 6-diphenylphenol, 2,3, 6-trimethylphenol, 2, 5-dimethylphenol are preferred, and 2, 6-dimethylphenol, 2,3, 6-trimethylphenol are more preferred.

The above phenol compounds may be used alone or in combination of 2 or more. When 2 or more phenolic compounds are used, the mixing ratio can be selected arbitrarily. For example, 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 can be used.

Aromatic solvents

The aromatic solvent is a good solvent for polyphenylene ether, and is at least one selected from the group consisting of benzene, toluene, xylene, and ethylbenzene. Toluene is preferred because residual solvent in the drying step can be easily removed.

The aromatic solvent is preferably a solvent substantially immiscible with water. The polymerization solution preferably contains substantially no solvent compatible with water.

Catalyst-

As the above catalyst, catalysts generally used for polymerization of polyphenylene ether may be used, including but not limited to: specific examples of the metal catalyst, the halide, the amine compound, and the mixture thereof include a mixture of a copper compound and an amine compound, a mixture of a manganese compound and an amine compound, and a mixture of a cobalt compound and an amine compound. Among them, a mixture of a copper compound and an amine compound is preferable.

Metal catalyst- -

As the above metal catalyst, a copper compound is preferable, including but not limited to a cuprous compound, a cupric compound or a mixture thereof. Examples thereof include cuprous chloride, cuprous bromide, cuprous sulfate, cuprous nitrate, cupric oxide, cupric chloride, cupric bromide, cupric sulfate, and cupric nitrate. Among them, cupric oxide, cuprous chloride, cupric chloride, cuprous bromide, and cupric bromide are preferable.

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

- - -halide- -

The halide 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 halides 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, also can be used in combination of 2 or more.

- - -amine compound- -

Examples of the amine compound include diamine compounds, secondary monoamine compounds, tertiary monoamine compounds, and the like. The amine compound may be used alone, or 2 or more kinds thereof may be used in combination.

The diamine compound is preferably a diamine compound represented by the following general formula (2).

As the catalyst, for example, a catalyst containing a copper compound, a halide and a diamine compound represented by the following general formula (2) can be used. By using such a catalyst, the polymerization rate can be further increased and the polymerization time can be further shortened. Further, the molecular weight after polymerization can be easily adjusted by adjusting the amount of the catalyst, the amount of oxygen blown, the polymerization time, and the like.

In the formula (2), R₅、R₆、R₇And R₈Each 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. R₉Represents a linear or branched alkylene group having 2 to 5 carbon atoms.

The diamine compound represented by the above general formula (2) is not particularly limited, and specific examples thereof include N, N, N ', N ' -tetramethylethylenediamine, N, N, N ' -trimethylethylenediamine, N, N ' -dimethylethylenediamine, N, N-dimethylethylenediamine, N-methylethylenediamine, N, N, N ', N ' -tetraethylethylenediamine, N, N, N ' -triethylethylenediamine, N, N ' -diethylethylenediamine, N, N-diethylethylenediamine, N-ethylethylenediamine, N, N-dimethyl-N ' -ethylethylenediamine, N, N ' -dimethyl-N-ethylethylenediamine, N, N ' -dimethylethylenediamine, N, N ' -methylethylenediamine, N, N, N ' -dimethylethylenediamine, N-methylethylenediamine, N-ethylethylenediamine, N, N, N ' -dimethylethylenediamine, N, N ' -dimethylethylenediamine, N, and the like,N-propylethylenediamine, N' -di-N-propylethylenediamine, N-isopropylethylenediamine, and the like. Among them, R in the formula (2) is preferable₅A diamine compound which is an alkylene group having 2 or 3 carbon atoms.

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 trimethylamine, triethylamine, tripropylamine, tributylamine, triisobutylamine, dimethylethylamine, dimethylpropylamine, allyldiethylamine, N-butyldimethylamine, diethylisopropylamine, and N-methylcyclohexylamine. The above-mentioned monovalent tertiary amine compound may be used alone, or 2 or more kinds 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 the order of addition after a part of the compound is added before 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 dimethylamine, diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, di-t-butylamine, dipentylamine, dihexylamine, dioctylamine, didecylamine, dibenzylamine, methylethylamine, methylpropylamine, methylbutylamine, cyclohexylamine, and the like.

Further, as the secondary monoamine compound, aromatic-containing secondary monoamine compounds can be used, and there are no particular limitations thereon, 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-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.

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. The surfactant may be trioctylmethylammonium chloride.

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

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 in the production of the polymerization solution.

The oxygen-containing gas is not particularly limited, and specifically, pure oxygen gas or a gas obtained by mixing oxygen with an arbitrary 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, which is required to reduce the oxygen content in the gas phase space of the reaction vessel to less than 10%.

< catalyst removal step >

In the catalyst removal step, the metal catalyst used as the catalyst is extracted to the chelating agent solution side by adding the chelating agent solution to the polyphenylene ether mixed solution after the polymerization step and stirring, and the polyphenylene ether mixed solution and the chelating agent solution are liquid-liquid separated to remove the metal catalyst in the polyphenylene ether mixed 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. 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 polyphenylene ether and the metal catalyst contained in the organic phase can be separated.

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

< concentration step >

The method for concentrating polyphenylene ether includes: a method in which the polyphenylene ether mixed solution is heated with a heat medium having a boiling point of the good solvent for polyphenylene ether or higher to discharge the good solvent for polyphenylene ether out of the system as vapor; a method of introducing the polyphenylene ether mixed solution into a pressure reducing tank to flash-vaporize a polymerization solvent such as an aromatic solvent; a method in which a polyphenylene ether mixed solution is heated under pressure and then reduced in pressure to flash-vaporize a polymerization solvent such as an aromatic solvent; and so on.

< deposition step >

A polar solvent which is a poor solvent for polyphenylene ether is added to the polyphenylene ether mixed solution, and a good solvent for polyphenylene ether and a poor solvent for polyphenylene ether are mixed to precipitate polyphenylene ether, thereby obtaining a slurry solution containing polyphenylene ether granules.

The polar solvent added to the polyphenylene ether mixed solution is a poor solvent which does not dissolve the polyphenylene ether at all or slightly dissolves the polyphenylene ether. The polar solvent is at least one polar solvent selected from the group consisting of ketones having 1 to 10 carbon atoms, alcohols having 1 to 10 carbon atoms, and water, and preferably 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, methyl ethyl ketone, and water. Among them, methanol, ethanol, isopropanol, n-butanol, 2-butanol, acetone, methyl ethyl ketone, or water is preferable.

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 the polar solvent to be added is preferably such that the mass ratio of the polar solvent to the good solvent in the polyphenylene ether mixed solution (mass of the polar solvent/mass of the good solvent) is 0.3 to 2.0, from the viewpoint that components other than polyphenylene ether are not precipitated but polyphenylene ether is easily precipitated.

< solid-liquid separation step >

As a first stage of separation of polyphenylene ether, the slurry liquid is separated into a cake of polyphenylene ether particles and a filtrate (separation liquid) using a solid-liquid separation apparatus. The solid-liquid separation apparatus is not particularly limited, and a rotary drum filter, a belt filter, a rotary drum filter, a single chamber rotary drum filter (Young filter), or the like can be used.

< cleaning Process >

The polyphenylene ether pellet cake separated in the solid-liquid separation step is impregnated with a large amount of a good solvent component such as an aromatic solvent. By washing the polyphenylene ether particle cake with a washing liquid containing a polar solvent, the content of a good solvent component contained in the polyphenylene ether particles can be reduced.

Polyphenylene ether particles contain impurities such as low molecular weight components and metals, and when the content of these impurities is reduced, polyphenylene ethers having excellent mechanical properties, heat aging properties, and the like can be obtained. When a cleaning liquid containing an aromatic solvent and a polar solvent is used as the cleaning liquid, impurities such as low-molecular-weight components and metals contained in the wet polyphenylene ether particles can be effectively reduced.

The aromatic solvent and the polar solvent used in the cleaning solution may be the same as or different from the aromatic solvent used in the polymerization step and the polar solvent used in the precipitation step. Among them, the same solvent is preferable from the viewpoint of efficiency.

The content of the aromatic solvent in the cleaning liquid is preferably 0.1 to 18.0% by mass, more preferably 5 to 15% by mass, and still more preferably 9.5 to 12% by mass, from the viewpoint of obtaining a polyphenylene ether having a low content of impurities such as low-molecular-weight components and catalyst metals.

In view of obtaining a polyphenylene ether having a low content of impurities such as low molecular weight components and catalyst metals, the content of the polar solvent in the cleaning solution is preferably 82 to 99.9 mass%, more preferably 85 to 95 mass%, and still more preferably 88 to 90.5 mass%.

Among these, the cleaning liquid is preferably a cleaning liquid containing 0.5 to 18.0% by mass of the aromatic solvent and 82.0 to 99.5% by mass of the polar solvent, more preferably a cleaning liquid containing 3.5 to 10% by mass of the aromatic solvent and 90 to 96.5% by mass of the polar solvent, and still more preferably a cleaning liquid containing 5.5 to 9.0% by mass of the aromatic solvent and 91.0 to 94.5% by mass of the polar solvent.

In the case where the washing step is performed 2 times or more, the washing liquids used in the respective washing steps may have the same composition or different compositions. From the viewpoint of cost and work efficiency, it is preferable to use cleaning liquids having the same composition.

In the case of performing the washing process for more than 2 times, the washing process comprises a solid-liquid separation operation, that is, while the washing liquid sprays the polyphenylene ether filter cake, the washing liquid sprayed through the filter cake is removed, and the washing liquid can be naturally discharged into a washing liquid storage container, or a pressure filtration or vacuum filtration operation is added on line, so that the washing liquid remained in the filter cake is more thoroughly discharged from the filter cake into the washing liquid storage container, and the washing efficiency is further improved.

< drying step >

The polyphenylene ether cake obtained in the washing step or the polyphenylene ether cake after preliminary drying may be subjected to a drying step in which the good solvent and the poor solvent are further separated by a dryer or the like. As the dryer, for example, various dryers, a combination of a heat exchanger and a flash tank, a devolatilizing extruder, and the like can be used. The various dryers can be selected from steam rotary dryers, rotary kiln dryers, blade dryers, film dryers and the like.

< recovery step >

The method for producing a polyphenylene ether of the present invention may further comprise a recovery step of obtaining a recovery solution containing at least one selected from the group consisting of a separation liquid separated in the solid-liquid separation step, a separation liquid separated in the washing step, and a condensate liquid obtained by liquefying the exhaust gas vaporized in the drying step, or a purified recovery solution obtained by purifying the recovery solution. The recovered solution or the purified recovered solution obtained in the recovery step may be used as the cleaning solution.

In the recovery step, the recovered solution may be purified by the following method to prepare a purified recovered solution.

Water is added to the recovered solution so that the mass ratio of water to the polyphenylene ether poor solvent contained in the recovered solution (water/polyphenylene ether poor solvent) is 0.5 to 1.5, and the two phases are separated into an organic phase containing a polyphenylene ether good solvent as a main component and an aqueous phase containing a polyphenylene ether poor solvent and water as main components. The two-phase separation may be performed by standing separation, or may be performed by using a liquid-liquid separator.

The separated organic phase is recovered, the obtained organic phase is supplied from the middle section of the distillation column, a waste liquid containing low molecular weight components such as oligomers, trimers, dimers and the like and the metal catalyst is withdrawn from the bottom of the column, and a good solvent for polyphenylene ether and an amine compound are recovered from the top or the side of the column. The good solvent for polyphenylene ether recovered from the column top can be reused as a good solvent in the above-mentioned polymerization step and the like.

The separated aqueous phase is supplied from the middle stage of the distillation column, an aqueous solution containing the metal catalyst is recovered from the bottom of the distillation column, and the polyphenylene ether poor solvent is recovered from the top of the distillation column.

The aqueous solution containing the metal catalyst recovered from the bottom of the column is recovered after adding a sulfide of an alkali metal and removing it as a solid. Can be reused in the recovery step. Further, the polyphenylene ether poor solvent recovered from the column top can be reused as a poor solvent in the above-mentioned precipitation step or the above-mentioned washing step.

The recovered solution or the purified recovered solution obtained by the above method can be used as the cleaning solution.

The poor solvent for polyphenylene ether purified by the above method is mixed with a proper amount of the good solvent for polyphenylene ether purified by the above method and used as a cleaning liquid, whereby low molecular weight components such as oligomers, trimers, dimers and the like and residual metals contained in the wet polyphenylene ether particles can be cleaned.

Drawings

FIG. 1 is a schematic view of a rotary drum filter press used in the present invention

Detailed Description

The present invention is further described below with reference to examples. It should be noted that the examples are not intended to limit the scope of the present invention, and those skilled in the art will appreciate that any modifications and variations based on the present invention are within the scope of the present invention.

The chemical reagents used in the following examples are conventional and are commercially available.

Description of the test methods:

1. preparation of polyphenylene ether suspensions

To a 30L reactor, 15 kg of toluene was added, followed by 5.6 g of Cu₂O, 54 g of 47% HBr solution, 12 g of N, N-di-tert-butylethylenediamine, 164 g of N, N-dimethylbutylamine, 56 g of N, N-di-N-butylamine and 6 g of trioctylmethylammonium chloride were added to a reaction vessel, 2, 6-dimethylphenol (4 kg of 2, 6-dimethylphenol dissolved in 2.5 kg of toluene) was added at a constant rate at 39 ℃ and oxygen-enriched air (oxygen content: 50%) was introduced to conduct polymerization. After the addition of the 2, 6-dimethylphenol solution was completed, the reaction was continued for 80 minutes.

After completion of the reaction, 2000 g of an aqueous solution containing 48 g of disodium ethylenediaminetetraacetate was added to the reaction solution, and stirred at 70 ℃ for 2.0 hours. Standing for 3 hours, layering, and discharging the aqueous solution at the bottom of the reaction kettle after layering. And (3) introducing hot water of 100 ℃ into a jacket of the reaction kettle, and connecting the top of the reaction kettle with a vacuum pump through a condenser to perform evaporation concentration. The content of the polyphenylene oxide in the solution after concentration is controlled to be 30-40% by measuring the distilled amount of good solvent toluene. Stopping heating, and introducing cold water into the jacket of the reaction kettle to reduce the temperature of the concentrated solution in the reaction kettle to about 50 ℃. Under stirring, an aqueous methanol solution twice the mass of the concentrated reaction solution was added to form a polyphenylene ether suspension.

2. Two filtration methods were compared: the experiment was repeated as described in 1 to obtain batches of polyphenylene ether suspension, which were washed by filtration in two ways. Wherein the original sample is: directly sampling the suspension, filtering in vacuum to form a filter cake, and analyzing the toluene content in the filter cake; and (5) drying, screening and analyzing the proportion of the micro powder in the mixture. Comparative example 1: filtration-1 time dispersion-refiltering-drying method

Experimental equipment: 2L of suction filtration funnel, a vacuum pump and a 4L of glass jacket stirring kettle

The operation method comprises the following steps:

A. carrying out vacuum filtration on 2L of the polyphenyl ether suspension obtained in the step 1 to form 0.516 kg of filter cake;

B. putting the obtained filter cake into a 4L stirring kettle filled with 1.56Kg of methanol, keeping stirring operation, and carrying out redispersion on of the filter cake;

C. controlling the temperature of hot water in a jacket to 40-50 ℃ in a stirring kettle, and controlling the linear speed of a paddle stirring end to 1-2m/s to disperse a filter cake, sampling 100 g every 10min at time intervals, performing vacuum filtration by using a Buchner funnel to obtain a filter cake sample, and detecting the content of toluene in the filter cake;

D. and drying the filter cake sample in a vacuum oven at 100 ℃, screening particles smaller than or equal to 100 micrometers from the dried sample, and weighing and calculating the proportion. And (5) counting the change of the proportion of the micro powder in the slurry.

Comparative example 2: filtration-1 time dispersion-refiltering-drying method

From polyphenylene ether suspensions of different batches, the whole procedure of comparative example 1 was repeated to examine the toluene content and the fine powder ratio in the filter cake.

Comparative example 3: filtration-1 time dispersion-refiltering-drying method

Table 1: results of comparative tests 1 to 3

As can be seen from the comparison of the experimental results, in the filtration-dispersion-refiltering-drying method, the dispersion time exceeds 20min, and about 30min is probably, the toluene in the polyphenylene oxide filter cake can be reduced to about 10 percent of the required toluene.

Comparative example 4: filtration-1 time dispersion-refiltering-2 times dispersion-3 times filtration-drying method

The operation method comprises the following steps:

A. carrying out vacuum filtration on 2L of the polyphenyl ether suspension obtained in the step 1 to form about 0.5 kg of filter cake;

C. and (3) controlling the temperature of hot water in the jacket to 40-50 ℃ in the stirring kettle, and controlling the linear speed of a paddle stirring end to be 2m/s to disperse the filter cake for 30 minutes, and carrying out vacuum filtration on a Buchner funnel to obtain a filter cake sample.

D. Putting the obtained filter cake into a 4L stirring kettle filled with 1.56Kg of methanol, keeping stirring operation, and carrying out redispersion on the filter cake for 2 times; the dispersion method is the same as the step C, and is characterized in that: sampling 100 g every 5min at time intervals, performing vacuum filtration by using a Buchner funnel to obtain a filter cake sample, and detecting the toluene content in the filter cake;

E. and drying the filter cake sample in a vacuum oven at 100 ℃, screening particles smaller than or equal to 100 micrometers from the dried sample, and weighing and calculating the proportion. And (5) counting the change of the proportion of the micro powder in the slurry.

Table 2: comparison test 4 (filtration-1 time dispersion-refilter-2 times dispersion-3 times filtration-drying method) results

Here the original sample 4 is a sample after one dispersion and filtration.

From a comparison of the results of the experiments, it can be seen that 2 dispersing steps lead to a considerable increase in the content of fines in the filter cake, from a proportion of 20.2% to a proportion of 26.1%.

Examples 5 to 7: continuous pressure filtration washing method

A rotary drum filter press as shown in FIG. 1 was used, and the diameter of the rotary drum was 60 cm. The surface of the rotary drum is provided with a filter tank, and the filter tank is 15cm long, 10cm wide and 2cm high. The filter tank on the rotary drum is divided into a feeding filter area, a washing area, a pre-drying area and a discharging area by a partition plate. The drum rotates for a circle to complete the processes of filtering, washing for many times, drying and discharging. The feeding amount is controlled to be 60L/h. Continuously washing in reverse direction for 5 times, wherein the dosage of detergent is 53.1L/h, the filtration and washing pressure is 4bar, and blowing N is dried₂Flow 15Nm³H is used as the reference value. After the operation is stable, taking a filter cake sample from a discharge hole to carry out toluene content analysis and detection; and then drying the sample in a vacuum oven at 100 ℃, screening particles less than or equal to 100 micrometers from the dried sample, and weighing and calculating the proportion.

Examples 5 to 7 used the same batches of polyphenylene ether suspensions as in comparative examples 1 to 3, respectively, and examined every 10min, and the results of the search are shown in Table 3.

Table 3: results of continuous pressure filtration washing method

Although the results in Table 3 were measured every 10 minutes from the discharge port, the actual filter cake was typically disposed of by filtration, washing and blow-drying for less than 10 minutes, typically 0.5-5 minutes, depending on the drum speed and the drum radius.

In examples 5-7, the filter cake was subjected to a complete filtration, washing and blow-drying cycle for a period of about 1 min. It can be seen that the toluene content in the cake can be stably controlled to 9% or less in the treatment time of about 1min in examples 5 to 7, compared to comparative examples 1 to 3. Meanwhile, the treated particles have low breakage rate, and the increase rate of fine particles (less than or equal to 100 microns) is controlled to be less than 2 percent.

Compared with the comparative example 4, the toluene content of the comparative example 4 is controlled within 10% after two times of dispersion cleaning, but the micro powder rate is as high as 20% -26%, while the micro powder rate of the examples 5-7 is controlled below 14%, and the effect is obvious.

Claims

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

a solid-liquid separation process, wherein the slurry liquid is subjected to solid-liquid separation to obtain a polyphenyl ether filter cake, and the separation process adopts a pressure filtration method, wherein the pressure is 1.2-10 bar;

a cleaning step of spraying and cleaning the filter cake obtained in the solid-liquid separation step with a cleaning solution and removing the sprayed cleaning solution; the cleaning solution is a polar solvent, and the polar solvent is at least one polar solvent selected from the group consisting of ketones with 1-10 carbon atoms, alcohols with 1-10 carbon atoms and water; or the cleaning solution is a mixed solvent composed of at least one aromatic solvent selected from the group consisting of benzene, toluene, xylene and ethylbenzene, and at least one polar solvent selected from the group consisting of ketones having 1 to 10 carbon atoms, alcohols having 1 to 10 carbon atoms and water, wherein the aromatic solvent content and the polar solvent content in the mixed solvent are 0.5 to 18.0 mass% and 82.0 to 99.5 mass%, respectively; the cleaning process adopts pressurized washing, and the pressure is 1.2-10 bar;

and a drying step of drying the polyphenylene ether cake.

2. The production method according to claim 1, wherein the pressure in the pressure filtration in the solid-liquid separation step is 2 to 6 bar.

3. The production method according to claim 2, wherein the pressure in the pressure filtration in the solid-liquid separation step is 2.5 to 5 bar.

4. The production method according to any one of claims 1 to 3, wherein the polyphenylene ether cake has a thickness of 10 to 200 mm.

5. The production method according to claim 4, wherein the polyphenylene ether cake has a thickness of 10 to 100 mm.

6. The production method according to claim 5, wherein the polyphenylene ether cake has a thickness of 10 to 50 mm.

7. The production method as claimed in any one of claims 1 to 3, wherein the washing liquid is used in an amount of 0.1 to 80 times by weight of the polyphenylene ether cake.

8. The production method according to claim 7, wherein the washing liquid is used in an amount of 1 to 10 times by weight of the polyphenylene ether cake.

9. The production method according to any one of claims 1 to 3, wherein the temperature of the washing liquid is 30 to 60 ℃.

10. The method of claim 9, wherein the temperature of the cleaning solution is 35-50 ℃.

11. The production method according to any one of claims 1 to 3, wherein the washing is carried out under pressure of 2 to 6 bar.

12. The method according to claim 11, wherein the washing is carried out under pressure of 2.5 to 5 bar.

13. The production method according to any one of claims 1 to 3, wherein the mixed solvent of the cleaning solution contains 3.5 to 10 mass% of the aromatic solvent and 90 to 96.5 mass% of the polar solvent.

14. The method according to claim 13, wherein the mixed solvent of the cleaning solution contains 5.5 to 9.0 mass% of the aromatic solvent and 91 to 94.5 mass% of the polar solvent.

15. The production method according to any one of claims 1 to 3, wherein the polar solvent in the cleaning solution is methanol.

16. The method according to any one of claims 1 to 3, wherein the aromatic solvent in the cleaning solution is toluene.

17. The method according to claim 13, wherein the polar solvent in the cleaning solution is methanol.

18. The method according to claim 13, wherein the aromatic solvent in the cleaning solution is toluene.

19. The method according to claim 14, wherein the polar solvent in the cleaning solution is methanol.

20. The method according to claim 14, wherein the aromatic solvent in the cleaning solution is toluene.

21. The method according to any one of claims 1 to 3, wherein the washing step is carried out by 2 to 8 or 2 to 8 stages of counter-current washing.

22. The method of claim 21, wherein the washing step uses 3 to 5 or 3 to 5 counter-current washing steps.

23. The method of any one of claims 1-3, wherein a pre-drying step is used to remove the cake surface solvent prior to the drying step.

24. The method of claim 23, wherein the pre-drying is performed using an inert gas purge.

25. The method of claim 24, wherein the pre-drying gas temperature is 1-200 ℃.

26. The method according to claim 24, wherein the inert gas is used in an amount of 0.01 to 50Nm³Perkg of polyphenylene ether filter cake.

27. The method according to claim 26, wherein the inert gas is used in an amount of 0.3 to 10Nm³Perkg of polyphenylene ether filter cake.

28. The method of claim 27, wherein the inert gas is used in an amount of 0.5 to 5.0Nm³Perkg of polyphenylene ether filter cake.

29. The method according to claim 23, wherein the solid-liquid separation step, the washing step and the pre-drying step are carried out continuously and sequentially.

30. The production method according to claim 29, wherein the solid-liquid separation step, the washing step and the preliminary drying step are carried out in one facility unit.

31. The method of claim 30, wherein the apparatus is selected from the group consisting of rotary drum filter presses, rotary disc filters, and horizontal belt filters.

32. The process according to claim 31, wherein the filter tank is disposed on the surface of the rotary drum filter press, the filter tank is divided into a feed filter zone, a washing zone, a pre-drying zone and a discharge zone by partition plates, the rotary drum is provided with a housing, and the housing is provided with a slurry inlet, a cleaning solution inlet, a pre-drying gas inlet and a scraper at a distance from each other; the partition plate is mounted on the surface of the drum, or on the inner surface of the housing facing the surface of the drum.

33. The method of claim 32, wherein the pressure is provided in the drum housing such that the solid-liquid separation step, the washing step and the pre-drying step are all performed under pressure, the pressure being 1.2 to 10 bar.

34. The method of claim 33, wherein the pressure is provided in the drum housing such that the solid-liquid separation step, the washing step and the pre-drying step are all performed under a pressure of 2 to 6 bar.

35. The process according to claim 32, wherein the washing amount of the washing liquid is 0.1 to 80Kg/Kg of the cake.

36. The process according to claim 35, wherein the washing amount of the washing liquid is 1 to 10Kg/Kg of the cake.

37. The method of claim 32, wherein the pre-dry purge inert gas is used in an amount of 0.01 Nm to 50Nm³Perkg of filter cake.

38. The method of claim 37, wherein the amount of inert gas used for pre-drying purgingIn the range of 0.3-10Nm³Perkg of filter cake.