Preparation method of polyphenyl ether resin with uniform particle size
By adding a swelling aid and subjecting the precipitation polymerization process to intense shearing, the problems of difficult particle size control and low yield were solved, achieving the preparation of polyphenylene ether with uniform particle size and high yield, simplifying the process and reducing wastewater treatment costs.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SHANGHAI ZHONGHUA TECH CO LTD
- Filing Date
- 2024-12-31
- Publication Date
- 2026-06-30
AI Technical Summary
In traditional precipitation polymerization processes, polymer precipitation and reaction occur simultaneously, making it difficult to control particle size and resulting in low product yield. Furthermore, existing solution-based processes are complex or increase wastewater treatment costs.
A precipitation polymerization method is used, in which a swelling aid is added and intense shearing is applied during the reaction to control the precipitation process of the polymer. By adjusting the stirring speed and the amount of swelling aid, polyphenylene ether products with uniform particle size are achieved.
The prepared polyphenylene ether product has controllable particle size and improved yield, while maintaining a narrow molecular weight distribution, which simplifies the process and reduces wastewater treatment costs.
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Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing polyphenylene ether resin with uniform particle size. Background Technology
[0002] Polyphenylene oxide (PPO) is one of the world's five major general-purpose engineering plastics. It possesses excellent high and low temperature resistance, good mechanical properties and dimensional stability, as well as good hot water resistance and creep resistance. Furthermore, the PPO molecular chain exhibits high symmetry and low polarity, resulting in a low and stable dielectric constant and low dielectric loss. It is widely used in electronics, automotive, machinery manufacturing, office equipment, aerospace, and other fields.
[0003] Industrially, the main processes for preparing polyphenylene oxide (PPO) are solution precipitation and precipitation methods. Their primary difference lies in the method by which PPO precipitates from the reaction medium. In the former, after the reaction is complete, the product solution is added to a weak solvent to precipitate PPO particles; in the latter, PPO particles precipitate simultaneously with the reaction. Each method has its advantages and disadvantages. Precipitation methods have a shorter process flow and a narrower molecular weight distribution, but particle size is difficult to control and the yield is relatively low.
[0004] The precipitation process affects the particle size and particle size distribution of the product. A suitable particle size can prevent particles that are too small from escaping during filtration, and also prevent particles that are too large from affecting subsequent drying and tableting processes. Therefore, there has been a great deal of research on this topic before.
[0005] US Patent 3789054 discloses a precipitation process for the continuous production of polyphenylene ether powder with a particle size of 5-500 micrometers. The reaction is carried out using two or more reactors connected in series. The product does not precipitate in the first reactor, but precipitates simultaneously in the second reactor. The conditions of the two reactors can be adjusted to obtain a controllable particle size. To impart suitable hardness to the polymer particles, a third reactor is used as an aging tank if necessary.
[0006] Patent CN112111057A discloses a continuous precipitation method for polyphenylene ether (PPE) using a solution process. This process employs two precipitation vessels. A certain proportion of good / bad solvent is added to the first vessel, while the second vessel further extracts the good solvent contained in the particles, resulting in denser particles. The final PPE product has 90% (by mass) particle size distributed between 100 and 2000 micrometers.
[0007] Patent CN117024786A discloses a solution-based method for the precipitation of polyphenylene ether (PPE). This process first involves vigorously mixing an aqueous solution containing a dispersant with an extracted product solution to form a dispersion. The dispersion is then mixed with a poor solvent at a temperature below 10°C, precipitating PPE particles. The final PPE product has an average diameter of 40-160 micrometers and a uniformity coefficient of less than 1.55.
[0008] Patent US3789054 uses two or more reactors in series, with a third reactor used as an aging tank when necessary, making the precipitation process complex. Patent CN112111057A produces products with particle sizes generally larger than 100 micrometers, which is detrimental to subsequent drying and tableting processes. Patent CN117024786A uses an aqueous solution containing dispersants, introducing dispersants such as polyvinylpyrrolidone, increasing the cost of subsequent wastewater and waste liquid treatment.
[0009] In traditional precipitation polymerization processes, polymer precipitation occurs simultaneously with the reaction; that is, once the polymer chains reach a certain molecular weight, they precipitate from the system as a precipitate. After the reaction, this precipitate is filtered, washed, and dried to obtain the final reaction product. Compared to solution-based polyphenylene ether (PPE) processes, traditional precipitation polymerization processes suffer from drawbacks such as difficulty in controlling product particle size and low yield. Therefore, developing a simpler, more efficient precipitation polymerization process for PPE with controllable product particle size is essential. Summary of the Invention
[0010] This invention employs a precipitation polymerization method, which involves an oxidative coupling reaction of phenolic monomers, a specific ratio of good / bad solvents for polyphenylene ether, an oxidant, and a catalyst. A swelling aid is added during the reaction to cause the precipitated polymer to swell. Then, by applying intense shear, the reaction product is simultaneously re-precipitated, resulting in a relatively uniform precipitate particle size. Surprisingly, after this swelling process, the final polyphenylene ether product exhibits controllable particle size, higher yield, and retains the narrow molecular weight distribution characteristic of precipitation polymerization products.
[0011] On one hand, the present invention provides a method for preparing polyphenylene ether, which includes the following steps:
[0012] 1) In a mixed solvent, phenolic monomers, oxygen, and catalyst undergo a polymerization reaction;
[0013] 2) Add a swelling aid to the reaction solution in step 1);
[0014] 3) Polyphenylene ether is obtained by precipitation under stirring at an online speed of 1.5-5 m / s;
[0015] The mixed solvent is a mixture of a good solvent for polyphenylene ether and a poor solvent for polyphenylene ether;
[0016] The mass ratio of good solvent to poor solvent of polyphenylene ether is 1:(0.5~2).
[0017] In one embodiment, the good solvent for polyphenylene ether is a conventional organic solvent in the art capable of dissolving polyphenylene ether, such as aromatic or substituted aromatic organic solvents, for example, benzene, toluene, xylene, chlorobenzene or trimethylbenzene, preferably toluene.
[0018] In one embodiment, the inferior solvent for polyphenylene ether is an organic solvent that is conventionally insoluble or difficult to dissolve polyphenylene ether, such as alcohol solvents or alkane solvents, for example, methanol, ethanol, isopropanol, cyclohexane or n-heptane, preferably methanol.
[0019] In one particular scheme, the mass ratio of good polyphenylene ether solvent to poor polyphenylene ether solvent is 1:(0.8 to 1.2), for example, 1:1.
[0020] In one embodiment, the phenolic monomer is a compound represented by Formula I:
[0021]
[0022] Among them, R 1 R 2 and R 3 Each of them is independently hydrogen, halogen, C1-C6 alkyl, halogenated C1-C6 alkyl or C1-C6 alkoxy, preferably hydrogen, halogen, C1-C6 alkyl, more preferably hydrogen, methyl or ethyl;
[0023] Preferably, the phenolic monomer is o-methylphenol, 2,3-dimethylphenol, 2,6-dimethylphenol, 2,3,6-trimethylphenol or 2,6-diethylphenol, and more preferably 2,6-dimethylphenol.
[0024] In one embodiment, the catalyst is a conventional catalyst used in the art for the catalytic synthesis of polyphenylene ethers, such as a metal amine composite catalyst;
[0025] Preferably, the metal amine composite catalyst is composed of a metal salt and an amine compound.
[0026] In one embodiment, the metal ions in the metal salt are preferably copper ions, manganese ions, cobalt ions, or chromium ions, with copper ions being the most preferred.
[0027] In one embodiment, the metal salt is CuBr.
[0028] In one embodiment, the amine compound is preferably one or more of secondary amine compounds, tertiary amine compounds, and diamine compounds;
[0029] Preferably, the molar ratio of the metal ion in the metal salt to the diamine compound is 1:1 to 1:5.
[0030] In one embodiment, the secondary amine compound is NH(C1-C4 alkyl)2, such as di-n-propylamine, diisopropylamine, di-n-butylamine, di-sec-butylamine, di-tert-butylamine, or N-isopropyltert-butylamine, preferably di-n-butylamine.
[0031] In one embodiment, the tertiary amine compound is N(C1-C4 alkyl)3, such as triethylamine, tri-n-propylamine, tri-n-butylamine, N,N-dimethyl-n-butylamine or N,N-dimethyl-n-pentylamine, preferably N,N-dimethylbutylamine.
[0032] In one embodiment, the diamine compound is a compound with the following structural formula:
[0033]
[0034] Among them, R 4 R 5 R 6 and R 7 Each is independently selected from hydrogen atoms or C1-C6 alkyl groups, wherein the C1-C6 alkyl groups are straight-chain alkyl groups or branched-chain alkyl groups;
[0035] R 8 It is a C2-C6 alkylene group, preferably -CH2CH2-;
[0036] Preferably, the diamine compound is N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylpropanediamine or N,N,N',N'-diisopropylethylenediamine, and most preferably N,N,N',N'-diisopropylethylenediamine.
[0037] In one embodiment, the molar ratio of the metal ions in the metal salt to the amine compound in the metal amine composite catalyst is 1:5 to 1:30.
[0038] The metal amine composite catalyst is composed of CuBr, N,N-dimethylbutylamine, di-n-butylamine and N,N,N',N'-diisopropylethylenediamine;
[0039] Preferably, the content of each component in the metal amine composite catalyst is as follows:
[0040] CuBr 0.1 to 1 part;
[0041] 1 to 6 parts of N,N-dimethylbutylamine;
[0042] 0.5 to 5 parts of di-n-butylamine;
[0043] 0.1 to 1 part of N,N,N',N'-diisopropylethylenediamine;
[0044] More preferably, the content of each component in the metal amine composite catalyst is as follows:
[0045] CuBr 0.2–0.5 parts;
[0046] 2.5–3.5 parts of N,N-dimethylbutylamine;
[0047] 0.5–1.5 parts of di-n-butylamine;
[0048] 0.4–0.6 parts of N,N,N',N'-diisopropylethylenediamine.
[0049] In one embodiment, the mass ratio of the mixed solvent to the phenolic monomer is (2-10):1, preferably (4-6):1, for example 5:1.
[0050] In one embodiment, the mass ratio of the catalyst to the phenolic monomer is (0.01–0.1):1, preferably (0.02–0.05):1.
[0051] In one embodiment, steps 1) and 2) are performed with stirring.
[0052] Preferably, the stirring is a conventional stirring method in the art, such as stirring with a stirring paddle;
[0053] Preferably, the linear velocity of the stirring is 1-2 m / s, more preferably 1-1.5 m / s, for example 1.4 m / s.
[0054] In one embodiment, the reaction temperature of the polymerization reaction in step 1) is a conventional temperature in the art, such as 25-45°C, preferably 30-35°C.
[0055] In one embodiment, step 1) includes the following steps: under the conditions of mixed solvent, catalyst and continuous oxygen supply, phenolic monomers are added (preferably continuously, more preferably continuously within 20 to 40 minutes) to undergo a polymerization reaction.
[0056] In one embodiment, the oxygen is continuously introduced;
[0057] Preferably, the oxygen flow rate is 1 to 10 ml / min per gram of phenol monomer, more preferably 2 to 4 ml / min, for example 3 ml / min.
[0058] In one embodiment, the purity of the oxygen is greater than 99%, preferably greater than 99.7%, for example, 99.9%.
[0059] In one approach, step 2) is performed when the polymerization reaction in step 1) is essentially complete, for example, when the oxygen consumption in the polymerization reaction in step 1) is ≤40% (e.g., ≤30% or 15%).
[0060] In one of the solutions,
[0061] In one scheme, step 2) includes the following steps: when the oxygen consumption of the polymerization reaction in step 1) is 0-30%, water is added to the reaction solution in step 1).
[0062] In one embodiment, the swelling aid is a solvent, such as water, that can cause the polyphenylene ether product generated in the reaction to swell.
[0063] In one embodiment, the mass ratio of the swelling aid to the phenolic monomer is (0.02–0.1):1, for example, 0.02:1, 0.04:1, 0.06:1, 0.08:1, or 0.1:1.
[0064] In one scheme, in step 2), the precipitate generated during the reaction swells after the addition of the swelling aid.
[0065] In one embodiment, after adding the swelling aid in step 2), the reaction is maintained for 5–20 minutes (preferably 10 minutes) before proceeding to step 3.
[0066] In one embodiment, the stirring linear velocity in step 3) is 2-4 m / s, for example 2.1, 2.8 or 3.5 m / s.
[0067] In one embodiment, when steps 1) and 2) are carried out under stirring, the stirring linear velocity in step 3) is 1.5 to 2.5 times the stirring linear velocity in steps 1) and 2).
[0068] In one embodiment, the stirring in step 3) is done by a stirring paddle.
[0069] In one approach, steps 1), 2), and 3) are carried out in the same reactor, preferably in the same reaction vessel.
[0070] In one embodiment, after step 3), the following steps are also included: adding a chelating agent, and washing and drying the product to obtain the polyphenylene ether.
[0071] In one embodiment, the chelating agent is one or more of EDTA, EDTA-Na, EDTA-2Na, EDTA-3Na, EDTA-4Na, citric acid, sodium citrate, and NTA (trisodium triacetate), preferably citric acid.
[0072] In one embodiment, the molar ratio of the chelating agent to the metal ions in the catalyst is 1:(1.5 to 3).
[0073] In one embodiment, the washing is performed using an alcohol solvent.
[0074] The preferred alcohol solvent is methanol.
[0075] In one embodiment, the raw materials for the preparation method consist of phenolic monomers, oxygen, a catalyst, and a swelling aid.
[0076] One possible solution includes the following steps:
[0077] 1) Under the stirring speed of 1-2 m / s, 2,6-dimethylphenol is added to a mixed solvent of methanol and toluene, a catalyst, and continuous oxygen flow to induce a polymerization reaction;
[0078] 2) Add water to the reaction solution from step 1);
[0079] 3) Polyphenylene ether is obtained by precipitation under stirring at an online speed of 2-4 m / s;
[0080] The mass ratio of methanol to toluene is 1:(0.5~2);
[0081] The mass ratio of water to the phenolic monomer is (0.02–0.1):1.
[0082] On the other hand, the present invention provides a polyphenylene ether, which is prepared by the above-described preparation method.
[0083] Without violating common sense in the field, the above-mentioned preferred conditions can be combined arbitrarily to obtain various preferred embodiments of the present invention.
[0084] The reagents and raw materials used in this invention are all commercially available.
[0085] The positive and progressive effects of this invention are as follows: the polyphenylene ether product obtained by the precipitation method has controllable particle size, higher product yield, and at the same time maintains the characteristics of narrow molecular weight distribution of the precipitation method product. Detailed Implementation
[0086] The present invention is further illustrated below by way of embodiments, but the invention is not limited to the scope of the embodiments described herein. Experimental methods in the following embodiments that do not specify specific conditions were performed according to conventional methods and conditions, or as selected according to the product instructions.
[0087] All ingredient quantities mentioned in the examples are by weight.
[0088] Intrinsic viscosity: Polyphenylene ether was prepared into a solution of a certain concentration with chloroform and then measured with an Ubbelohde viscometer.
[0089] Particle size (D50) and particle size distribution: The particle size and particle uniformity coefficient of the product were measured using a laser particle size analyzer.
[0090] Yield: Calculated using the following equation.
[0091] Yield (%) = (mass of dried polyphenylene ether product) / (amount of 2,6-dimethylphenol) * 100.
[0092] Oxygen consumption: Oxygen input to the reactor per unit time - Oxygen output from the reactor per unit time
[0093] The above time units can be adjusted according to the detection needs, such as 1s, 5s, 10s, 20s, 30s, etc.
[0094]
[0095] Example 1
[0096] The reactor was stirred, with the impeller speed controlled at 1.4 m / s. 250 g of toluene, 250 g of methanol, and a metal amine composite catalyst (0.35 g CuBr, 3 g N,N-dimethylbutylamine, 1 g di-n-butylamine, and 0.5 g N,N,N',N'-diisopropylethylenediamine) were added sequentially. Oxygen (99.9% purity) was continuously introduced at a flow rate of 300 ml / min. The reactor temperature was controlled at 30-35℃. 100 g of 2,6-dimethylphenol melt was continuously added over 35 minutes. After the addition was complete, the reaction was continued at a constant temperature. When the oxygen consumption percentage decreased to 30%, 6 g of water was added, and the precipitate became a swollen system. Stirring continued for 10 minutes, then oxygen was stopped, and the stirring speed was adjusted to 2.8 m / s. The system rapidly precipitated, yielding a polyphenylene ether precipitate.
[0097] 1 g of 40% citric acid solution was added to the polyphenylene ether precipitate, the reactor was heated to 50°C and kept at that temperature for 1 hour, the polyphenylene ether precipitate was then filtered, washed with 500 g of pure methanol, dried, and a white polyphenylene ether powder was prepared.
[0098] Example 2
[0099] After the addition of materials, the reaction was continued at a constant temperature. When the oxygen consumption rate decreased to 30%, 2g of water was added, and the precipitate became a swollen system. After stirring for 10 minutes, the oxygen was stopped, and the stirring speed was adjusted to 2.8m / s. The system precipitated rapidly, and a polyphenylene ether precipitate was obtained. Other steps were the same as in Example 1.
[0100] Example 3
[0101] After the addition of materials, the reaction was continued at a constant temperature. When the oxygen consumption rate decreased to 30%, 10g of water was added, and the precipitate became a swollen system. After stirring for 10 minutes, the oxygen was stopped, and the stirring speed was adjusted to 2.8m / s. The system precipitated rapidly, and a polyphenylene ether precipitate was obtained. Other steps were the same as in Example 1.
[0102] Example 4
[0103] After the addition of materials, the reaction was continued at a constant temperature. When the oxygen consumption rate decreased to 30%, 6g of water was added, and the precipitate became a swollen system. After stirring for 10 minutes, the oxygen was stopped, and the stirring speed was adjusted to 2.1m / s. The system precipitated rapidly, and a polyphenylene ether precipitate was obtained. Other steps were the same as in Example 1.
[0104] Example 5
[0105] After the addition of materials, the reaction was continued at a constant temperature. When the oxygen consumption rate decreased to 30%, 6g of water was added, and the precipitate became a swollen system. After stirring for 10 minutes, the oxygen was stopped, and the stirring speed was adjusted to 3.5m / s. The system precipitated rapidly, and a polyphenylene ether precipitate was obtained. Other steps were the same as in Example 1.
[0106] Example 6
[0107] After the addition of materials, the reaction was continued at a constant temperature. When the oxygen consumption rate decreased to 15%, 6g of water was added, and the precipitate became a swollen system. After stirring for 10 minutes, the oxygen was stopped, and the stirring speed was adjusted to 2.8m / s. The system precipitated rapidly, and a polyphenylene ether precipitate was obtained. Other steps were the same as in Example 1.
[0108] Example 7
[0109] After the addition of materials, the reaction was continued at a constant temperature. When the oxygen consumption rate decreased to 0%, 6g of water was added, and the precipitate became a swollen system. After stirring for 10 minutes, the oxygen was stopped, and the stirring speed was adjusted to 2.8m / s. The system precipitated rapidly, and a polyphenylene ether precipitate was obtained. Other steps were the same as in Example 1.
[0110] Comparative Example 1
[0111] After the addition of materials, the reaction was continued at a constant temperature. When the oxygen consumption rate decreased to 30%, stirring was continued for 10 minutes and then the oxygen was stopped to obtain a polyphenylene ether precipitate. Other procedures were the same as in Example 1.
[0112] Comparative Example 2
[0113] After the addition of materials, the reaction was continued at a constant temperature. When the oxygen consumption rate decreased to 30%, 14 parts of water were added, and the precipitate became a solution. After stirring for another 10 minutes, the oxygen was stopped, and the stirring speed was adjusted to 2.8 m / s. No precipitation occurred in the system, and polyphenylene ether was not obtained by precipitation method. Other procedures were the same as in Example 1.
[0114] Comparative Example 3
[0115] After the addition of materials, the reaction was continued at a constant temperature. When the oxygen consumption rate decreased to 30%, 6 parts of water were added, and the precipitate became a solution. After stirring for 10 minutes, the oxygen was stopped, and the stirring speed was maintained at 1.4 m / s. No precipitation occurred in the system, and polyphenylene ether was not obtained by precipitation method. Other procedures were the same as in Example 1.
[0116] Test Example 1
[0117] The test results of the products obtained from the examples and comparative examples are shown in Table 1 below:
[0118] Table 1. Specifications of Polyphenylene Ether Powder
[0119]
[0120] As shown in Table 1 above, adding swelling aids and increasing the stirring speed in the later stage of the reaction can produce polyphenylene ether products with more uniform particle size and higher yield. By adjusting the amount of swelling aids and the stirring speed, polyphenylene ether products with different particle sizes can be obtained, and the particle uniformity coefficient of the obtained polyphenylene ether products is also smaller.
[0121] The introduction of swelling aids has little effect on the intrinsic viscosity of polyphenylene ether and does not affect its application range. Excessive dosage of swelling aid or low stirring speed is detrimental to the redeposition of the swollen system, leading to complex reaction control.
[0122] Furthermore, the addition of swelling aids allows the system to swell, releasing the catalyst encapsulated in the precipitate and continuing to catalyze the reaction of small-molecule polyphenylene ethers, ultimately significantly improving the polymerization yield (for precipitation-based polyphenylene ether synthesis, yield improvement is difficult; an increase of 0.5-1% is considered a significant improvement). The timing of adding the swelling aid has a significant impact on the final yield; adding it too early reduces the reaction rate, leading to a lower yield of the final product.
Claims
1. A method for preparing polyphenylene ether, comprising the following steps: 1) In a mixed solvent, phenolic monomers, oxygen, and catalyst undergo a polymerization reaction; 2) Add a swelling aid to the reaction solution from step 1); 3) Polyphenylene ether is obtained by precipitation under stirring at an online speed of 1.5-5 m / s; The mixed solvent is a mixture of a good solvent for polyphenylene ether and a poor solvent for polyphenylene ether; The mass ratio of good solvent to poor solvent of polyphenylene ether is 1:(0.5~2).
2. The method for preparing polyphenylene ether according to claim 1, characterized in that, The preparation method satisfies one or more of the following conditions: (1) The good solvent for the polyphenylene ether is an aromatic or substituted aromatic organic solvent, such as benzene, toluene, xylene, chlorobenzene or trimethylbenzene, preferably toluene; (2) The inferior solvent of the polyphenylene ether is an alcohol solvent or an alkane solvent, such as methanol, ethanol, isopropanol, cyclohexane or n-heptane, preferably methanol; (3) The mass ratio of good polyphenylene ether solvent to poor polyphenylene ether solvent is 1:(0.8~1.2), for example 1:1; (4) The mass ratio of the mixed solvent to the phenolic monomer is (2-10):1, preferably (4-6):1, for example 5:1; (5) The mass ratio of the catalyst to the phenolic monomer is (0.01-0.1):1, preferably (0.02-0.05):1; (6) Steps 1) and 2) are carried out under stirring; Preferably, the stirring is done by a stirring paddle; Preferably, the linear velocity of the stirring is 1-2 m / s, more preferably 1-1.5 m / s, for example 1.4 m / s; (7) The reaction temperature of the polymerization reaction in step 1) is 25-45℃, preferably 30-35℃; (8) The oxygen is continuously introduced; Preferably, the oxygen flow rate is 1 to 10 ml / min per gram of phenol monomer, more preferably 2 to 4 ml / min, for example 3 ml / min; (9) Proceed to step 2) when the oxygen consumption of the polymerization reaction in step 1) is ≤40% (e.g., ≤30% or ≤15%). (10) The swelling aid is water; (11) The mass ratio of the swelling aid to the phenolic monomer is (0.02-0.1):1, for example 0.02:1, 0.04:1, 0.06:1, 0.08:1 or 0.1:1; (12) In step 2), after adding the swelling aid, maintain the reaction for 5 to 20 minutes (preferably 10 minutes) before proceeding to step 3); (13) The stirring linear velocity in step 3) is 2-4 m / s, for example 2.1, 2.8 or 3.5 m / s; (14) When steps 1) and 2) are carried out under stirring, the stirring linear velocity in step 3) is 1.5-2.5 times the stirring linear velocity in steps 1) and 2). (15) The stirring in step 3) is done by a stirring paddle; (16) Steps 1), 2) and 3) are carried out in the same reactor, preferably in the same reaction vessel.
3. The method for preparing polyphenylene ether according to claim 1, characterized in that, The phenolic monomer is a compound represented by Formula I: wherein R 1 , R 2 and R 3 are each independently hydrogen, halogen, Ci-C6-alkyl, halogen-Ci-C6-alkyl or Ci-C6-alkoxy, preferably hydrogen, halogen, Ci-C6-alkyl, more preferably hydrogen, methyl or ethyl; Preferably, the phenolic monomer is o-methylphenol, 2,3-dimethylphenol, 2,6-dimethylphenol, 2,3,6-trimethylphenol or 2,6-diethylphenol, and more preferably 2,6-dimethylphenol.
4. The method for preparing polyphenylene ether according to claim 1, characterized in that, Step 1) includes the following steps: In the presence of a mixed solvent, a catalyst, and continuous oxygen supply, phenolic monomers are added (preferably continuously, more preferably continuously over 20 to 40 minutes) to induce a polymerization reaction.
5. The method for preparing polyphenylene ether according to claim 1, characterized in that, The catalyst is a metal amine composite catalyst, which is composed of metal salts and amine compounds; Preferably, the metal ions in the metal salt are copper ions, manganese ions, cobalt ions, or chromium ions, with copper ions being the most preferred. Preferably, the amine compound is one or more of secondary amine compounds, tertiary amine compounds, and diamine compounds.
6. The method for preparing polyphenylene ether according to claim 5, characterized in that, The preparation method satisfies one or more of the following conditions: (1) The metal salt is CuBr; (2) In the metal amine composite catalyst, the molar ratio of the metal ion in the metal salt to the amine compound is 1:5 to 1:30; (3) The secondary amine compound is NH(C1-C4 alkyl)2, such as di-n-propylamine, diisopropylamine, di-n-butylamine, di-sec-butylamine, di-tert-butylamine or N-isopropyltert-butylamine, preferably di-n-butylamine; (4) The tertiary amine compound is N(C1-C4 alkyl)3, such as triethylamine, tri-n-propylamine, tri-n-butylamine, N,N-dimethyl-n-butylamine or N,N-dimethyl-n-pentylamine, preferably N,N-dimethylbutylamine; (5) The diamine compound is a compound with the following structural formula: wherein R 4 , R 5 , R 6 and R 7 are each independently selected from a hydrogen atom or a C1-C6alkyl group, wherein the C1-C6alkyl group is a linear alkyl group or a branched alkyl group; R 8 C2-C6alkylene, preferably -CH2CH2-; Preferably, the diamine compound is N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethylpropanediamine or N,N,N',N'-diisopropylethylenediamine, and most preferably N,N,N',N'-diisopropylethylenediamine; (6) The molar ratio of the metal ion in the metal salt to the diamine compound is 1:1 to 1:
5.
7. The method for preparing polyphenylene ether according to claim 5, characterized in that, The metal amine composite catalyst is composed of CuBr, N,N-dimethylbutylamine, di-n-butylamine and N,N,N',N'-diisopropylethylenediamine; Preferably, the content of each component in the metal amine composite catalyst is as follows: CuBr 0.1 to 1 part; 1 to 6 parts of N,N-dimethylbutylamine; 0.5 to 5 parts of di-n-butylamine; 0.1 to 1 part of N,N,N',N'-diisopropylethylenediamine; More preferably, the content of each component in the metal amine composite catalyst is as follows: CuBr 0.2–0.5 parts; 2.5–3.5 parts of N,N-dimethylbutylamine; 0.5–1.5 parts of di-n-butylamine; 0.4–0.6 parts of N,N,N',N'-diisopropylethylenediamine.
8. The method for preparing polyphenylene ether according to claim 1, characterized in that, Following step 3), the following steps are also included: adding a chelating agent, and washing and drying the product to obtain the polyphenylene ether; Preferably, the preparation method satisfies one or more of the following conditions: (1) The chelating agent is one or more of EDTA, EDTA-Na, EDTA-2Na, EDTA-3Na, EDTA-4Na, citric acid, sodium citrate and trisodium triacetate, preferably citric acid; (2) In one embodiment, the molar ratio of the chelating agent to the metal ions in the catalyst is 1:(1.5-3); In one embodiment (3), the washing is performed using an alcohol solvent, preferably methanol.
9. The method for preparing polyphenylene ether according to claim 1, characterized in that, It includes the following steps: 1) Under stirring at an online speed of 1-2 m / s, 2,6-dimethylphenol, oxygen and catalyst undergo polymerization in a mixed solvent of methanol and toluene; 2) Add water to the reaction solution from step 1); 3) Polyphenylene ether is obtained by precipitation under stirring at an online speed of 2-4 m / s; The mass ratio of methanol to toluene is 1:(0.5~2); The mass ratio of water to the phenolic monomer is (0.02–0.1):
1.
10. A polyphenylene ether, which is prepared by the method of any one of claims 1-9.