A method for preparing polyphenylene ether

Abstract

The present application provides a method for preparing polyphenyl ether, which produces polyphenyl ether with molecular weight distribution below 2.0 by using toluene and water as solvent, and increases the utilization of catalyst and reduces the amount of waste water by multiple reuse of copper catalyst enriched in water phase. The method has simple process, high catalyst utilization, and is suitable for large-scale production.

Description

Technical Field

[0001] The present invention relates to the field of organic synthesis, and in particular to a method for preparing polyphenylene ether. Background Art

[0002] Polyphenylene ether (PPE) has excellent properties. Its molecular chain is highly symmetrical and has low polarity, resulting in excellent electrical properties such as a low and stable dielectric constant and low dielectric loss. Furthermore, since the PPE molecular chain contains a large number of aromatic groups and the main chain is highly rigid, it has excellent heat resistance and many other characteristics, such as self-flammability and low density. PPE is widely used in electrical, automotive, cable, photovoltaic power generation and other fields. With the development of 5G communication technology in recent years, PPE has been widely developed and applied in 5G antenna covers, signal transmission base stations, electronic circuit boards and other communication fields due to its low dielectric constant and low dielectric loss properties, which are beneficial for low loss and high fidelity in electromagnetic signal transmission.

[0003] Regarding the preparation of polyphenylene ether in two-phase solvents, Percec et al. first reported in 1986 in the article "Functional Polymers and Sequential Copolymers by Phase Transfer Catalysis" the polymerization of 2,6-dimethylphenol in a two-phase medium of water and benzene to synthesize PPO. In 1999, Ahn et al. used copper complex catalysts in the article "Biphasic coupling polymerization of 2,6-dimethylphenol using surface-active copper complex catalysts" to carry out the oxidative polymerization of 2,6-dimethylphenol in a two-phase medium of water / chloroform. In 2002, Gamez et al. also reported in their article "A Simple and Selective Biphasic Catalytic System for the Oxidative Polymerization of 2,6-Dimethylphenol" the oxidative coupling of DMP to obtain PPO in a two-phase medium of water and organic solvent.

[0004] According to existing research, the preparation of PPO by oil-water two-phase polymerization has the following advantages:

[0005] ①The reaction takes place at the interface between the two phases, with high selectivity, high activity and high conversion rate;

[0006] ② The selection range of organic solvents has been expanded, reducing the use of organic solvents;

[0007] ③The reaction speed is faster than that of precipitation polymerization;

[0008] ④Since the catalyst acts at the oil-water interface, the stereoselectivity of the catalyst can be controlled.

[0009] CN109836568A proposes a method for preparing polyphenyl ether copolymer in oil / water two-phase medium, expecting to realize the regulation of polyphenyl ether molecular weight through polymerization reaction on the two-phase interface. However, the scheme only regards the toluene / water two-phase reaction as a conventional emulsion polymerization, and does not reflect the advantages of the scheme for preparing polyphenyl ether in two-phase solvent in catalyst recovery, material viscosity control, etc. Moreover, the preparation focus of the patent is always on polyphenyl ether with large molecular weight, and the advantages of two-phase solution in reaction selectivity and product molecular weight distribution when preparing medium and small molecular weight polyphenyl ether are not reflected.

[0010] CN102604075B and CN103145975B propose a method for preparing polyphenyl ether in aqueous phase, which can be prepared without using organic solvent, reducing the solvent cost. However, due to the low solubility of the polymer in water, a large amount of surfactant has to be used; in order to increase the reaction rate, a large amount of alkali, catalyst, and ligand are used, and the reaction time is also prolonged, which leads to a substantial increase in the actual cost of the scheme, and also makes the scheme lose the value of industrialization.

[0011] The post-treatment of polyphenyl ether in the prior art also includes the recovery of catalyst and other problems, and a certain treatment cost is required, therefore, how to develop a suitable method for preparing polyphenyl ether has important significance. SUMMARY

[0012] The technical problem to be solved by the present application is that the catalyst utilization rate is low in the existing preparation process, which is not conducive to large-scale production.

[0013] In order to solve the above technical problems, the present application provides a method for preparing polyphenyl ether, which comprises the following steps:

[0014] (1) adding raw monomer, ligand and toluene in a first reaction container to obtain a mixture, wherein the raw monomer has a structure as shown in formula I;

[0015] … Formula I

[0016] In formula I, X1 and X2 are respectively selected from halogen atom, C1-C 10 primary alkyl or C1-C 10 secondary alkyl, C2-C 10 alkenyl, C3-C 10 alkenylalkyl, C2-C 10 alkynyl, C3-C 10 alkynylalkyl, C1-C10 aminoalkyl or C1-C 10 hydroxyalkyl, or a combination of at least two of any of the foregoing; Y1and Y2are each selected from the group consisting of hydrogen, a halogen atom, C1-C 10 primary alkyl, C1-C 10 secondary alkyl, C2-C 10 alkenyl, C3-C 10 alkenylalkyl, C2-C 10 alkynyl, C3-C 10 alkynylalkyl, C1-C 10 aminoalkyl or C1-C 10 hydroxyalkyl, or a combination of at least two of any of the foregoing;

[0017] The ligand includes an amine compound and / or a compound shown in Formula II.

[0018] Formula II

[0019] In Formula II, R1, R2, R4, R5are each independently a hydrogen atom or an alkyl group, the alkyl group being a linear alkyl group or a branched alkyl group, and R3is a saturated alkyl group of 2 carbon atoms.

[0020] The reaction solvent includes an aromatic hydrocarbon or a halogenated hydrocarbon.

[0021] The mass percentage of the raw monomer in toluene is 10% to 70%, and the amount of the ligand is 0.1% to 100% of the amount of the raw monomer.

[0022] (2) A copper catalyst and water are added to a second reaction container, and the mixture in step (1) is added to the second reaction container to react, and an organic phase is separated to obtain a crude product; the amount of the copper catalyst is 0.1% to 100% of the amount of the raw monomer; and the amount of the water is 0.1 to 2 times the volume of the mixture in step (1).

[0023] (3) The crude product obtained in step (2) is added to a third reaction container, a chelating agent and water are added to wash, and after standing and layering, an organic phase and an aqueous phase are obtained, the organic phase is separated into a fourth reaction container, and after first precipitation and second precipitation, the polyphenyl ether is obtained.

[0024] The copper catalyst and water added in step (2) can be replaced by the aqueous phase recovered in step (2), and the chelating agent and water added in step (3) can be replaced by the aqueous phase recovered in step (3).

[0025] The preparation method provided by the present application produces polyphenyl ether with a molecular weight distribution of 2.0 or less by using toluene and water as solvents. The multiple reuse of the water-phase enriched copper catalyst increases the utilization rate of the catalyst and reduces the amount of waste water. The method has a simple process and high catalyst utilization rate, and is suitable for large-scale production.

[0026] In the present application, the reaction solvent includes substances that can dissolve the polymerization monomer and the catalyst, including aromatic hydrocarbons (such as benzene, toluene, ethylbenzene, xylene), halogenated hydrocarbons (such as chloroform, dichloroethane, trichloroethane, chlorobenzene); and toluene is preferred.

[0027] In the present application, the amount used in the reaction is the molar amount, except for the volume or mass specifically indicated.

[0028] Preferably, in step (1), the raw material monomer is 2,6-dimethylphenol; and the mass percentage of the raw material monomer in the solvent is 50%.

[0029] Preferably, in step (1), the ligand is a combination of an amine compound and a compound represented by formula II; and the amount of the ligand is 1% of the amount of the raw material monomer for the amine compound and 1% of the amount of the raw material monomer for the compound represented by formula II.

[0030] In the present application, the use of amine can significantly increase the selectivity of the polymerization reaction and reduce the generation of byproduct quinone substances on the one hand, and increase the polarity and basicity of the solvent, which also has a positive effect on the selectivity of the reaction on the other hand. At the same time, the amine compound also acts as a phase transfer catalyst, which helps the reaction between the oil and water phases.

[0031] The compound represented by formula II is a diamine compound. The complexing constant of the diamine compound with copper is higher than that of ordinary amine ligands, and the use of the diamine compound can significantly reduce the amount of ligand and achieve high reaction selectivity. During the multiple reuse of the water phase of the reaction solution, the amine ligand with weak copper ion combination is mostly lost to the organic phase during the phase separation process, so it needs to be supplemented in the raw material. However, the diamine compound has low loss during the phase separation process, and does not need to be frequently supplemented during the reuse of the water phase.

[0032] Preferably, the amine compound includes any one of primary amine, tertiary amine or secondary amine. The primary amine includes any one of n-propylamine, isopropylamine, n-butylamine, sec-butylamine, tert-butylamine, n-pentylamine, n-hexylamine or cyclohexylamine.

[0033] The secondary amine includes any one of di-n-propylamine, di-n-butylamine, di-tert-butylamine, n-butyl n-pentylamine, morpholine or di-n-hexylamine, and preferably morpholine. The morpholine, as a cyclic secondary amine, can provide the same complexing capacity as the secondary amine such as piperidine, and has stronger water solubility, so that the proportion of the loss in the toluene solvent in the water / toluene two-phase system is lower, and the prepared polyphenyl ether enveloped impurities are less.

[0034] The tertiary amine includes any one of triethylamine, tri-n-propylamine, tri-n-butylamine, dimethyl n-butylamine or dimethyl n-pentylamine.

[0035] Preferably, the compound shown in the formula II is N , N , N ´, N ´-tetramethyl-1,3-diaminopropane or N , N ´-di-tert-butyl ethylenediamine.

[0036] Preferably, the copper catalyst in the step (2) includes any one or a combination of at least two of cuprous compound, copper compound or copper salt.

[0037] Preferably, the copper catalyst is any one of cuprous chloride, cuprous bromide, copper chloride or copper bromide.

[0038] Preferably, the amount of the copper catalyst is 2% of the amount of the raw material monomer.

[0039] In the present application, the copper catalyst and water are added into the reaction kettle, stirred and dissolved, the materials in the mixing kettle are uniformly mixed and then added into the reaction kettle. The reactor is replaced by nitrogen gas under stirring, so that the oxygen content is below 2%, the temperature in the kettle is increased to the reaction temperature, the two phases are uniformly mixed under the condition of heat preservation and stirring, and then oxygen is introduced to start the reaction. The monomer raw material is gradually converted into the product polyphenyl ether, and the viscosity of the system gradually increases. The reaction time is determined according to the molecular weight of the target product. After the reaction is completed, the oxygen input is stopped, the stirring is turned off, and the reaction liquid is layered by standing. The upper organic phase of the reaction kettle is pumped into the washing kettle, and the lower water phase is retained and can be used repeatedly.

[0040] Since the copper salt can be used multiple times by phase separation, the amount of the catalyst can be increased here to increase the polymerization reaction rate. The present application can control the reaction rate by the amount of the copper salt.

[0041] Preferably, in the step (2), the inorganic salt is dissolved in water, and the mass percentage of the inorganic salt in water is 0.1% to 30%.

[0042] The inorganic salt can be sodium chloride, potassium chloride, sodium bromide, potassium bromide, lithium chloride, sodium sulfate, calcium chloride, ammonium chloride, preferably sodium chloride. The addition of the inorganic salt in the aqueous phase can provide a polar environment for the solution, maintain the activity of the catalyst, and increase the density of the aqueous phase, which is helpful for the separation of the two phases. In the present application, the mass percentage of the inorganic salt is preferably 10%. If the mass percentage is too low, the emulsion will be difficult to separate; if the mass percentage is too high, the stirring and mixing effect will be affected, and the reaction rate will be low.

[0043] Preferably, the temperature of the reaction in step (2) is 30-70°C, preferably 50°C.

[0044] Preferably, the reaction time in step (2) is 20-150 min, preferably 40-80 min.

[0045] Preferably, the reaction in step (2) is carried out in an atmosphere with a volume concentration of oxygen of 21%-100%, preferably 90%-100%.

[0046] In the present application, the amount of oxygen used per hour is 2.2 times the equivalent of the raw monomer.

[0047] Preferably, the chelating agent in step (3) includes any one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetate, trisodium ethylenediaminetetraacetate, tetrasodium ethylenediaminetetraacetate, sodium citrate, or trisodium nitrilotriacetate.

[0048] Preferably, the mass concentration of the chelating agent in water is 1%-20%, preferably 5%.

[0049] In the third reaction vessel, the total amount of chelating agent and water solution is 0.1-2 times, preferably 0.5 times, the amount of the reaction solution of the previous step.

[0050] Preferably, both the first precipitation and the second precipitation use a poor solvent.

[0051] Preferably, the poor solvent includes C1-C4 alcohol and / or water, preferably a methanol aqueous solution.

[0052] Preferably, in the first precipitation, the mass ratio of the organic phase to the poor solvent is (0.2-5):1, preferably 0.8:1.

[0053] Preferably, in the second precipitation, the mass ratio of the organic phase to the poor solvent is (0.2-1.2):1, preferably 0.7:1.

[0054] In the present application, the material is discharged from the precipitation kettle and subjected to filtration and drying to obtain a powder-type polyphenyl ether product.

[0055] The slurry after the first precipitation needs to be maintained at 40-70℃ and stirred for 30 min, on the one hand to reduce the residual solvent in the particulate matter, and on the other hand to remove residual small molecular impurities, including quinone byproducts, by washing. The solid is settled by standing, and the supernatant is discharged from the tank, which contains a small amount of low molecular weight polyphenyl ether and most of the quinone byproducts. This step separates the low molecular weight products in the product, further reducing the molecular weight distribution of the product polyphenyl ether;

[0056] In the second precipitation, after adding the poor solvent, the slurry of polyphenyl ether solid and liquid coexists is formed by rapid stirring, and finally the solid product is obtained by filtration and drying. By dividing the precipitation step into two steps, not only the amount of poor solvent used is saved, but also the impurities and low molecular weight products in the solid product are separated, further reducing the molecular weight of the product step by step.

[0057] In the present application, the first reaction vessel is generally a mixing tank, the second reaction vessel is generally a reaction tank, the third reaction vessel is generally a washing tank, and the fourth reaction vessel is generally a precipitation tank.

[0058] In the preparation process of the present application, the slurry of polyphenyl ether solid and liquid coexists is generally formed after precipitation. The filtration method generally uses known conventional methods for separating solid and liquid phases, such as suction filtration tank, optional filtration, centrifugal filtration, etc.

[0059] The above-mentioned drying method of polyphenyl ether can be selected from known industrial drying methods such as vacuum drying, nitrogen drying, etc., and known industrial dryers such as rotary drum dryers, etc.

[0060] In the process of recycling and reusing, only the raw monomer and amine ligand need to be added in the mixing tank, and the aqueous phase of the reaction tank and the washing tank can be used multiple times without adding diamine ligand.

[0061] The implementation of the present application has the following beneficial effects:

[0062] (1) The polymerization reaction occurs in a toluene / water mixed system to obtain polyphenyl ether. On the one hand, due to the difference in solubility of the catalyst copper complex in the organic phase and the aqueous phase, the raw monomer has considerable solubility in water, and the oxidation coupling in the aqueous phase is dominant in the early stage of the reaction. As the polymerization degree of the reaction product increases, the reaction gradually shifts to the interface between the two phases, and the reaction rate decreases significantly, which is controllable. On the other hand, the product is enriched in the organic phase, and since the long chain of polyphenyl ether is difficult to contact and combine with the catalyst in the aqueous phase, the redistribution reaction between the polymer chains is inhibited, greatly reducing the degree of increase in the molecular weight distribution of the polymer caused by the redistribution reaction.

[0063] (2) Compared with the precipitation method for preparing polyphenyl ether, the reaction environment of toluene / water phase has two advantages, one is that the molecular weight distribution is narrower, and the low molecular weight polyphenyl ether can be more uniformly dissolved in the organic phase to participate in polymerization, while in the non-aqueous phase reaction or precipitation method reaction, only the outer layer of the particles participates in polymerization; the second is that polyphenyl ether with a molecular weight of 10000-20000 can be prepared, and more types of polyphenyl ether products can be prepared compared with the aqueous phase reaction or precipitation method reaction.

[0064] (3) Compared with the preparation of polyphenyl ether by homogeneous method, the toluene / water system can reduce the amount of solvent toluene, can meet the stirring efficiency while reducing the amount of toluene, avoid the system viscosity too high after reducing the amount of toluene, which leads to stirring difficulty, and then leads to insufficient mixing of the system, local overheating, increase of side reaction, and uneven reaction, which increases the molecular weight distribution of the product.

[0065] (4) The polyphenyl ether preparation method provided in the present application reduces the recovery step of the catalyst, and the cuprous salt catalyst can be recovered after simple separation, and the aqueous phase containing the catalyst can be reused for many times, reducing the unnecessary cost caused by catalyst loss. DETAILED DESCRIPTION

[0066] In order to make the purpose, technical scheme and advantages of the embodiments of the present application more clear, the technical scheme in the embodiments of the present application will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor are within the scope of protection of the present application.

[0067] Embodiment 1

[0068] The present embodiment provides a method for preparing polyphenyl ether with a molecular weight of 8000 daltons

[0069] (1) The mixing kettle is a 15L kettle, and 4.98kg (40mol, 98%) of raw material monomer 2,6-dimethylphenol and 5kg of reaction solvent toluene are added to the kettle, and the material is mixed uniformly under stirring.

[0070] (2) The reactor is a 25L reactor, 40.4g of cuprous bromide (0.4mol, 98%) is added into the reactor, the catalyst ligand morpholine 40g (0.4mol) and N,N-di-tert-butyl ethylenediamine 68.4g (0.4mol) are added into the reactor, 500g of sodium chloride (10%) and 4.5kg of water are added into the reactor, and the mixture is stirred and dissolved to be uniform. The mixture in the reactor is pumped into the reaction reactor after being mixed, stirring is maintained while the reactor is replaced by nitrogen to make the oxygen content below 2%. The temperature in the reactor is increased to 50°C, and after 5min of heat preservation and stirring, oxygen is introduced from the oxygen inlet at the bottom of the reactor at a rate of 2.82kg / h. After the reaction starts, the stirring power is increased to make the water phase and the organic phase not stratified, and as the monomer raw material is gradually converted into the product polyphenyl ether, the viscosity of the system gradually increases. After 55min of timing reaction since the oxygen is introduced, the oxygen input is stopped, and nitrogen is introduced to reduce the oxygen content above the liquid surface to below 2%. The stirring is turned off, and the reaction liquid is stratified after 15min of standing. The upper organic phase of the reaction reactor is pumped into the washing reactor by a pump. The lower water phase in the reactor can be reused for multiple times. The water phase is sampled and titrated to determine the content of cuprous ions.

[0071] (3) The washing reactor is a 25L reactor, 4.75kg of water and 250g of chelating agent ethylenediaminetetraacetic acid disodium salt (5%) are added into the reactor, and the mixture is stirred and dissolved to be uniform. After the upper organic phase in the reaction reactor is pumped into the washing reactor, the stirring is started to mix the two phases, the mixture is heated to 45°C, and after 30min of heat preservation and stirring, the organic phase and the water phase are stratified after 15min of standing. The upper organic phase of the washing reactor is pumped into the precipitation reactor by a pump. The lower water phase in the washing reactor can be reused for multiple times. The water phase of the washing reactor is sampled, and the EDTA content of the water phase is measured by titration.

[0072] (4) The precipitation reactor is a 30L reactor, the upper organic phase of the washing reactor is pumped into the precipitation reactor, and after the temperature of the solution is reduced to below 30°C, 12.5kg of 95% methanol is added into the reactor, and the stirring is maintained to make the polyphenyl ether solid precipitate. After 30min of stirring, the polyphenyl ether solid is precipitated after 15min of standing, and the upper clear liquid of the material is removed by a pump for a total of 15.3kg. 10kg of 95% methanol water (0.7:1) is added into the reactor again, the stirring is maintained for 30min to make the precipitation complete, and the wet product obtained after filtration is placed into a vacuum drying drum dryer for drying at a temperature gradually increased from 40°C to 120°C until the volatile content of the product is reduced to below 0.5wt%, and a total of 5.35kg of polyphenyl ether powder is obtained. The intrinsic viscosity of the polymer is measured by using an Ubbelohde viscometer according to the method in GBT1632-1993, and the molecular weight Mn=7780 and the molecular weight distribution D=1.81 of the polymer are calculated.

[0073] Example 2

[0074] In this example, the waste liquid in Example 1 is used as the reaction liquid for reaction

[0075] (1) Put monomer 2,6-dimethylphenol 4.98 kg (40 mol, 98%) and 5 kg reaction solvent toluene into a mixing kettle, and mix the materials uniformly under stirring.

[0076] (2) Keep the water phase remaining after separation in the reaction kettle in example 1, pump the materials in the mixing kettle into the reaction kettle, keep stirring and replace the reactor with nitrogen to make the oxygen content below 2%. Increase the temperature in the kettle to 50℃, keep stirring for 5 min, then input oxygen from the oxygen inlet at the bottom of the kettle, and the oxygen flow rate is 2.82 kg / h. Increase the stirring power after the reaction starts to make the water phase and the organic phase mix fully, and as the monomer raw material is gradually converted into the product polyphenyl ether, the viscosity of the system gradually increases. Stop the oxygen input after 55 min of timing reaction from the start of oxygen input, input nitrogen to reduce the oxygen content above the liquid surface to below 2%. Turn off the stirring, and let stand for 15 min to separate the reaction liquid into layers. Pump the upper organic phase of the reaction kettle into the washing kettle through a pump. Keep the lower water phase in the kettle, and take a sample from the water phase to determine the cuprous ion content by titration.

[0077] (3) Keep the EDTA solution remaining after separation in the washing kettle in example 1, pump the upper organic phase of the reaction kettle into the washing kettle, and mix the two phases under stirring. Increase the temperature of the mixed liquid to 45℃, keep stirring for 30 min, then let stand for 15 min to separate the organic phase and the water phase. Pump the upper organic phase of the washing kettle into the precipitation kettle through a pump. Keep the lower water phase in the washing kettle, and take a sample from the water phase of the washing kettle to determine the EDTA content of the water phase by titration.

[0078] (4) Pump the upper organic phase of the washing kettle into the precipitation kettle, and add the poor solvent in batches to make the product precipitate according to the same method as in example 1, and obtain polyphenyl ether powder 5.35 kg through the steps of filtration and drying. Determine the intrinsic viscosity of the polymer by using an Ubbelohde viscometer according to the method in GBT1632-1993, and calculate to obtain the molecular weight Mn=7975 and the molecular weight distribution D=1.85 of the polymer.

[0079] Example 3, Example 4 and Example 5

[0080] Repeat the steps of example 2, and use the water phase of the reaction kettle and the washing kettle repeatedly. Take a sample from the water phase of the reaction kettle and the washing kettle to determine the cuprous ion content and the EDTA content by titration according to the same method as in example 2. Determine the intrinsic viscosity of the polymer by using an Ubbelohde viscometer, and calculate to obtain the molecular weight and the molecular weight distribution of the polymer.

[0081] Example 6

[0082] This example provides a method for preparing 16000 Dalton polyphenyl ether

[0083] (1) Put monomer 2,6-dimethylphenol 4.98 kg (40 mol, 98%) and 7.5 kg reaction solvent toluene into a mixing kettle, and mix the materials uniformly under stirring.

[0084] (2) Keep the water phase remaining after separation in the reaction kettle in example 5, pump the materials in the mixing kettle into the reaction kettle, keep stirring and replace the reactor with nitrogen to make the oxygen content below 2%. Increase the temperature in the kettle to 50°C, keep stirring for 5 min, then input oxygen from the oxygen inlet at the bottom of the kettle, and the oxygen flow rate is 2.82 kg / h. After the reaction starts, increase the stirring power to make the water phase and the organic phase mix fully, and as the monomer raw material is gradually converted into the product polyphenyl ether, the viscosity of the system gradually increases. After 80 min of timing reaction since the oxygen input, stop the oxygen input, input nitrogen to blow to make the oxygen content above the liquid surface below 2%. Turn off the stirring, and stand for 15 min to make the reaction liquid stratify. Pump the upper organic phase of the reaction kettle into the washing kettle through a pump. Keep the lower water phase in the kettle, and take a sample from the water phase to determine the cuprous ion content by titration.

[0085] (3) Keep the EDTA solution remaining after separation in the washing kettle in example 1, pump the upper organic phase of the reaction kettle into the washing kettle, and mix the two phases under stirring. Increase the temperature of the mixed liquid to 50°C, keep stirring for 30 min, and stand for 15 min to make the organic phase and the water phase stratify. Pump the upper organic phase of the washing kettle into the precipitation kettle through a pump. Keep the lower water phase in the washing kettle, take a sample from the water phase of the washing kettle, and measure the EDTA content in the water phase by titration.

[0086] (4) Pump the upper organic phase of the washing kettle into the precipitation kettle, and then add 15.6 kg of 95% methanol to the kettle while keeping stirring, so that the polyphenyl ether solid is precipitated. After stirring for 30 min, stand for 15 min to make the polyphenyl ether solid precipitate, and remove the upper clear liquid of the material through a pump, and the amount is 21 kg. Add 5 kg of 95% methanol water (0.7:1) to the kettle again, and stir for 30 min to make the precipitation complete. Then, filter and dry the polyphenyl ether powder in the same way as in example 1 to obtain 5.35 kg of polyphenyl ether powder. Use the Ubbelohde viscometer to measure the intrinsic viscosity of the polymer according to the method in GBT1632-1993, and calculate to obtain that the molecular weight Mn of the polymer is 15753, and the molecular weight distribution D is 1.94.

[0087] Example 7

[0088] The example provides a method for preparing 4000 Dalton polyphenyl ether

[0089] (1) The mixed tank was charged with monomer 2,6-dimethylphenol 4.98 kg (40 mol, 98%) and 4 kg of reaction solvent toluene, and the materials were mixed uniformly under stirring.

[0090] (2) The water phase remaining after the separation in Example 6 was retained in the reactor, and the materials in the mixed tank were pumped into the reactor. The reactor was replaced with nitrogen to reduce the oxygen content to below 2%. The temperature in the reactor was raised to 50°C, and after 5 min of stirring, oxygen was introduced from the bottom of the reactor at a rate of 2.82 kg / h. After the reaction started, the stirring power was increased to ensure that the water phase and the organic phase were mixed well. As the monomer raw material was gradually converted into polyphenyl ether, the viscosity of the system gradually increased. After 40 min of reaction, oxygen was stopped, and nitrogen was introduced to reduce the oxygen content above the liquid surface to below 2%. The stirring was stopped, and the reaction liquid was allowed to stand for 15 min to separate the layers. The upper organic phase in the reactor was pumped into the washing tank. The lower water phase in the tank was retained, and the sample was taken for titration to determine the cuprous ion content.

[0091] (3) The washing tank was charged with the EDTA solution remaining after the separation in Example 1, and the upper organic phase in the reactor was pumped into the washing tank. The two phases were mixed under stirring, and the mixture was heated to 40°C. After 30 min of stirring, the mixture was allowed to stand for 15 min to separate the organic phase and the water phase. The upper organic phase in the washing tank was pumped into the precipitation tank. The lower water phase in the washing tank was retained, and the sample was taken for titration to determine the EDTA content in the water phase.

[0092] (4) The upper organic phase in the washing tank was pumped into the precipitation tank, and the temperature of the solution was reduced to below 30°C. Then, 11.2 kg of 95% methanol was added to the tank under stirring to precipitate the polyphenyl ether. After 30 min of stirring, the mixture was allowed to stand for 15 min to precipitate the polyphenyl ether. The upper clear liquid was removed by pumping, and 5 kg of 95% methanol was added to the tank. After 30 min of stirring, the mixture was filtered and dried to obtain 5.35 kg of polyphenyl ether powder. The intrinsic viscosity of the polymer was determined by using an Ubbelohde viscometer according to the method in GBT1632-1993, and the molecular weight Mn was calculated to be 3887, and the molecular weight distribution D was 1.72.

[0093] Example 8

[0094] The difference between this example and Example 1 is that the ligand of the catalyst is replaced by 1.2 mol of triethylamine, and other raw material dosages or operating procedures are consistent with Example 1. After the phase separation, washing and precipitation steps, a total of 5.35 kg of polyphenyl ether powder is obtained, with a molecular weight Mn = 7142 and a molecular weight distribution D = 1.87. The copper ion concentration of the water phase sampled from the reactor is calculated to be 7.43 x 10 - 2 mol / L, and the catalyst loss is 7.12%.

[0095] Example 9

[0096] The difference between this example and Example 1 is that the ligand of the catalyst is replaced by 1.2 mol of di-n-propylamine, and other raw material dosages or operating procedures are consistent with Example 1. After the phase separation, washing and precipitation steps, a total of 5.35 kg of polyphenyl ether powder is obtained, with a molecular weight Mn = 7325 and a molecular weight distribution D = 1.91. The copper ion concentration of the water phase sampled from the reactor is calculated to be 7.21 x 10 -2 mol / L, and the catalyst loss is 9.88%.

[0097] Example 10

[0098] The difference between this example and Example 1 is that the ligand of the catalyst is replaced by 1.2 mol of n-propylamine, and other raw material dosages or operating procedures are consistent with Example 1. After the phase separation, washing and precipitation steps, a total of 5.35 kg of polyphenyl ether powder is obtained, with a molecular weight Mn = 6854 and a molecular weight distribution D = 1.85. The copper ion concentration of the water phase sampled from the reactor is calculated to be 6.55 x 10 -2 mol / L, and the catalyst loss is 18.12%.

[0099] Waste water treatment

[0100] (1) A total of 5.25 kg of waste water in the reactor is added with 30 g of sodium sulfide and heated and stirred to precipitate copper sulfide solid. After filtering out the solid, the remaining liquid can be reused.

[0101] (2) A total of 5.25 kg of waste water in the reactor is added with 30 g of sodium sulfide and heated and stirred to precipitate copper sulfide solid. The copper sulfide solid is filtered out for recovery. The remaining liquid is concentrated by distillation and then cooled to precipitate sodium chloride solid for recovery.

[0102] Comparative Example 1

[0103] This comparative example uses the precipitation method to synthesize polyphenyl ether

[0104] (1) Add raw materials monomer 2,6-dimethylphenol 4.98 kg (40 mol, 98%) and 15 kg of reaction solvent methanol to the mixing kettle, and mix the materials uniformly under stirring.

[0105] (2) The reactor is a 25L reactor, and 40.4g of cuprous bromide (0.4mol, 98%), 40g of catalyst ligand morpholine (0.4mol), 68.4g of N,N-di-tert-butyl ethylenediamine (0.4mol), and 100g of solvent methanol are added into the reactor. The mixture is stirred and dissolved to be uniform. After the mixture in the mixing reactor is mixed, it is pumped into the reaction reactor. The reactor is replaced with nitrogen to make the oxygen content below 2%. The temperature in the reactor is increased to 50°C, and after 5min of heat preservation and stirring, oxygen is introduced from the oxygen inlet at the bottom of the reactor at a rate of 2.82kg / h. After the reaction starts, the stirring power is increased, and as the monomer raw material is gradually converted into the product polyphenyl ether, solid particles are gradually precipitated in the system. After 55min of timing reaction since the oxygen is introduced, the oxygen input is stopped, and nitrogen is introduced for purging to reduce the oxygen content above the liquid surface to below 2%. The stirring is turned off, and the reaction liquid is allowed to stratify for 15min. The upper clear liquid is removed using a pump, 5kg of toluene is injected into the reactor, and the solid is dissolved by stirring. The solution is introduced into the washing reactor.

[0106] (3) The EDTA solution remaining in the washing reactor after the reaction solution in the reaction reactor is pumped into the washing reactor, and the washing is carried out in the same way. After the washing, the upper organic phase in the washing reactor is pumped into the precipitation reactor.

[0107] (4) The upper organic phase in the washing reactor is pumped into the precipitation reactor, and the product is precipitated by adding a poor solvent in batches in the same way as in Example 1. After filtration and drying, polyphenyl ether powder is obtained, with a total weight of 5.35kg. The intrinsic viscosity of the polymer is determined by using an Ubbelohde viscometer according to the method in GBT1632-1993, and the molecular weight Mn=4189 and the molecular weight distribution D=2.25 are calculated.

[0108] Comparative Example 2

[0109] This comparative example uses a homogeneous method to synthesize polyphenyl ether

[0110] (1) The raw material monomer 2,6-dimethylphenol 1.0kg (8mol, 98%) and 5kg of reaction solvent toluene are added into the mixing reactor, and the mixture is stirred to be uniform.

[0111] (2) The reactor is a 25L reactor, 8.1g of cuprous bromide (0.08mol, 98%) is added into the reactor, the catalyst ligand morpholine 8.0g (0.08mol) and N,N-di-tert-butyl ethylenediamine 13.7g (0.08mol) and the solvent 20g of methanol are added. Stirring dissolves and mixes uniformly. After mixing the materials in the reactor, pump them into the reaction reactor, keep stirring while replacing the reactor with nitrogen to make the oxygen content below 2%. Increase the temperature in the reactor to 50°C, keep stirring for 5min, then input oxygen from the oxygen inlet at the bottom of the reactor, the oxygen rate is 2.82kg / h. After the reaction starts, increase the stirring power, as the monomer raw material gradually converts into the product polyphenyl ether, the viscosity of the materials in the system gradually increases. After 35min from the start of oxygen input, stop the oxygen input, input nitrogen to reduce the oxygen content above the liquid surface to below 2%. Turn off the stirring and guide the solution into the washing reactor.

[0112] (3) The EDTA solution remaining in the washing reactor after the last batch of reaction is kept, the solution in the reaction reactor is pumped into the washing reactor, and the washing is heated and stirred in the same way, and the upper organic phase in the washing reactor is pumped into the precipitation reactor.

[0113] (4) The upper organic phase in the washing reactor is pumped into the precipitation reactor, and after the solution temperature is reduced to below 30°C, 7.5kg of 95% methanol is added into the reactor, and the stirring is kept during the period to make the polyphenyl ether solid precipitate. After stirring for 30min, stand for 15min to make the polyphenyl ether solid precipitate, and use a pump to remove the upper clear liquid of the materials, a total of 12.1kg. Add 1kg of 95% methanol water (0.7:1) into the reactor again, and stir vigorously for 30min to make the precipitation complete. Then, filter and dry the polyphenyl ether powder in the same way as in Example 1 to obtain a total of 1.05kg. The intrinsic viscosity of the polymer is determined by using the Ubbelohde viscometer according to the method in GBT1632-1993, and the molecular weight Mn=7627 and the molecular weight distribution D=1.89 are calculated.

[0114] The products of the above examples and comparative examples are calculated for molecular weight distribution, and the results are shown in Table 1 below:

[0115] Table 1 Molecular weight distribution data table of products of examples and comparative examples

[0116]

[0117] From the data in Table 1, it can be seen that:

[0118] The sampling titration data of the water phase in the reactor show that the copper catalyst has low loss in the multiple reactions and phase separation processes, and can meet the multiple reuse. Examples 1-7 show that the multiple reuse of the water phase in the present application does not significantly affect the reaction activity, and the polyphenylene ether product can be stably obtained. In Examples 8-10, different ligands are used to prepare the reaction catalyst, and in addition to a certain effect on the reaction activity, the change of the ligand also affects the loss ratio of the catalyst during the process.

[0119] Examples 6-7 show that the method proposed in the present application can meet the production of polyphenylene ether with a molecular weight range of 4000-16000, and only the solvent amount needs to be adjusted in the mixing kettle, and the reaction time needs to be changed during the reaction, so that different types of polyphenylene ether products can be obtained.

[0120] Comparative Examples 1-2 show that the polyphenylene ether preparation method proposed in the present application can reduce the amount of solvent toluene, increase the use efficiency of the catalyst, and at the same time, obtain high-quality polyphenylene ether products comparable to the homogeneous polymerization method.

[0121] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application, but not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacement for part of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solution deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A method for preparing polyphenylene ether, characterized in that: The method comprises the following steps: (1) adding raw material monomers 2,6-dimethylphenol and toluene into a first reaction container and mixing to obtain a mixed material; the mass percentage of the raw material monomers in toluene is 10% to 70%; (2) Add copper catalyst and water, as well as ligand morpholine and N , N -di-tert-butylethylenediamine, the mixture of step (1) is added to the second reaction vessel for reaction, and the organic phase is separated to obtain a crude product; the amount of the copper catalyst is 0.1% to 100% of the amount of the raw monomer; the amount of water is 0.1 to 2 times the volume of the mixture in step (1); the amount of morpholine is 1% of the amount of the raw monomer, N , N - The amount of di-tert-butylethylenediamine used is 1% of the amount of the raw monomer; (3) adding the crude product obtained in step (2) to a third reaction vessel, adding a chelating agent and water for washing, and allowing to stand for stratification to obtain an organic phase and an aqueous phase, separating the organic phase into a fourth reaction vessel, and obtaining the polyphenylene ether after a first precipitation and a second precipitation; The copper catalyst and water added in step (2), and the ligand morpholine and N , N - The combination of di-tert-butylethylenediamine is replaced by the aqueous phase recovered in step (2), and the chelating agent and water added in step (3) are replaced by the aqueous phase recovered in step (3).

2. The method according to claim 1, characterized in that The mass percentage of the raw material monomer in the solvent is 50%.

3. The method according to claim 1, characterized in that The copper catalyst in step (2) includes any one of cuprous compounds, copper compounds or copper salts, or a combination of at least two of them.

4. The method according to claim 3, characterized in that The copper catalyst is any one of cuprous chloride, cuprous bromide, cupric chloride or cupric bromide; the amount of the copper catalyst is 2% of the amount of the raw material monomer.

5. The method according to claim 1, wherein In step (2), an inorganic salt is dissolved in the water; the mass percentage of the inorganic salt in the water is 0.1% to 30%.

6. The method according to claim 1, characterized in that The chelating agent in step (3) includes any one of ethylenediaminetetraacetic acid, disodium ethylenediaminetetraacetic acid, trisodium ethylenediaminetetraacetic acid, tetrasodium ethylenediaminetetraacetic acid, sodium citrate or trisodium nitrilotriacetic acid; the mass concentration of the chelating agent in water is 1% to 20%.

7. The method according to claim 1, characterized in that In the fourth reaction container, a poor solvent is used for both the first precipitation and the second precipitation; the poor solvent includes a C1-C4 alcohol and / or water; In the first precipitation, the mass ratio of the organic phase to the poor solvent is (0.2-5):1; in the second precipitation, the mass ratio of the organic phase to the poor solvent is (0.2-1.2):1.

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