A dihydroxyl terminated low molecular weight polyphenylene ether and a method for its synthesis

Abstract

The application relates to the technical field of high polymer synthesis, in particular to a double-end hydroxyl low-molecular-weight polyphenyl ether and a synthesis method thereof, the number-average molecular weight of the double-end hydroxyl low-molecular-weight polyphenyl ether is 500-5000; the double-end hydroxyl low-molecular-weight polyphenyl ether is polymerized by a monomer of formula (1) and a monomer of formula (2); wherein B1, B2 and B3 are each independently selected from hydrogen, a halogen atom, substituted or non-substituted C1-C8 alkyl, substituted or non-substituted C6-C 30 aromatic group, and R is any one of a covalent bond, an oxygen atom, a sulfur atom, a carbonyl group, a sulfone group, a sulfoxide group, an amino group and substituted or non-substituted C1-C8 alkylene; the polyphenyl ether prepared by the application has a low number-average molecular weight, and Mw / Mn is less than or equal to 1.10, which indicates that the prepared polyphenyl ether has high purity.

Description

Technical Field

[0001] This invention relates to the field of polymer synthesis technology, specifically to a low molecular weight polyphenylene ether with two hydroxyl-terminated ends and its synthesis method. Background Technology

[0002] Polyphenylene oxide (PPO) is a class of high-performance engineering plastics, with polymers manufactured from 2,6-dimethylphenol via oxidative coupling being a representative example. PPO's outstanding properties include its low specific gravity, only 1.07 g / cm³. 3 It has excellent temperature resistance, and can work for a long time between 120℃ and 170℃; good hydrolysis resistance, and its performance does not decrease in strong acids and alkalis; and excellent insulation, and can work for a long time at high frequency voltage while maintaining its dielectric constant. Therefore, it is widely used in the fields of automobiles, electronics, water treatment, cables, and PCBs.

[0003] Recently, with the rapid development of the information age, especially the advent of the 5G era, the transmission of high-throughput data has placed higher demands on the dielectric properties of electronic and electrical materials. Polyphenylene ether (PPE) with its low dielectric constant and low dielectric loss makes it one of the ideal substrates for high-frequency, high-speed PCBs. However, conventional molecular weight PPE used in thermoplastic applications (intrinsic viscosity IV ≥ 0.25 dL / g) has poor compatibility with thermosetting resins (such as epoxy resins and cyanate ester resins), limiting its application in the electronics and electrical fields. Furthermore, due to the high melt viscosity of conventional molecular weight PPE, its processing performance is poor during extrusion granulation and / or injection molding.

[0004] To overcome the aforementioned shortcomings of conventional molecular weight polyphenylene ethers (PPEs) in the electronics and electrical appliance industries, low molecular weight PPEs with dual-terminated hydroxyl groups are considered one of the ideal materials. While inheriting the low dielectric and low dielectric loss properties of conventional molecular weight PPEs, the increased content of dual-terminated hydroxyl groups allows them to be used in thermosetting applications. This overcomes the poor compatibility between conventional molecular weight PPEs and thermosetting resins, and greatly improves processability and moldability.

[0005] There are generally two methods for manufacturing low molecular weight polyphenylene ethers with hydroxyl-terminated ends.

[0006] One method involves reacting a dihydric phenol with a conventional molecular weight polyphenylene ether via a redistribution reaction at a specific temperature using an initiator to obtain a low molecular weight polyphenylene ether with hydroxyl-terminated ends. Patent CN1040565 discloses a method for producing low molecular weight polyphenylene ether resin via redistribution. First, a monohydric phenol is oxidatively polymerized to produce a conventional molecular weight polyphenylene ether. Then, a byproduct of the reaction, tetramethylbiphenyl diquinone (TMDQ), is used as an initiator to redistribute the added dihydric phenol with the generated conventional molecular weight polyphenylene ether to produce a low molecular weight polyphenylene ether containing hydroxyl-terminated ends. This method effectively avoids the addition of new peroxide initiators during the production of low molecular weight polyphenylene ether with hydroxyl-terminated ends. Patent CN101389691 discloses a method for manufacturing low molecular weight polyphenylene ether. This method involves reacting a raw material polyphenylene ether with a number average molecular weight of 10,000 or higher and a polyphenolic compound via a redistribution reaction initiated by a free radical initiator. This produces a low molecular weight polyphenylene ether containing hydroxyl-terminated ends, with the proportion of components with a number average molecular weight of 20,000 or higher controlled to be less than 10% by mass and the number average molecular weight less than 4,000. Although the above redistribution reaction can produce low molecular weight polyphenylene ether containing dihydroxyl groups, the redistribution reaction has the following drawbacks: the low molecular weight polyphenylene ether product with dihydroxyl groups produced by the redistribution reaction still contains high molecular weight polyphenylene ether (number average molecular weight greater than 20,000), which causes uneven distribution when manufacturing high frequency and high speed PCBs, thus affecting product use; the peroxide initiator added in the redistribution reaction cannot be completely removed and enters the product, causing product cracking and shortening its service life.

[0007] The copolymerization of dihydric and monohydric phenols is a second method for manufacturing hydroxyl-terminated low molecular weight polyphenylene ethers (PPEs). Patent CN101326215 discloses the oxidative copolymerization of monohydric and dihydric phenols in the presence of a copper-amine complex catalyst to obtain hydroxyl-terminated PPEs. This oligomer has an intrinsic viscosity of 0.04-0.15 dL / g, and each molecule contains 1.8-2 terminal hydroxyl groups. Patents CN100352848 and US6689920 disclose methods for the oxidative copolymerization of monohydric and dihydric phenols to produce hydroxyl-terminated PPEs, wherein the preferred dihydric phenol is 2,2',3,3',5,5'-hexamethyl-4,4'-biphenol. Although the above patents describe the manufacturing methods of hydroxyl-terminated PPEs in detail, careful analysis of the methods disclosed in these patents reveals that some monohydric and / or dihydric phenols fail to react. These unreacted monohydric and / or dihydric phenols, especially some dihydric phenols that are highly harmful to human health, either enter the product untreated, causing significant toxicity to humans and the environment; or, although they are removed through post-treatment, it inevitably increases production costs. Therefore, it is still necessary to find an efficient production method that completely converts the raw material monohydric and dihydric phenols into dihydroxyl-terminated low molecular weight polyphenylene ether during the manufacturing process, thereby avoiding the harm to humans and the environment caused by the toxicity of the raw materials, while simultaneously reducing production costs. Summary of the Invention

[0008] Purpose of the invention: To address the above-mentioned technical problems, this invention proposes a low molecular weight polyphenylene ether with dual hydroxyl terminals and its synthesis method.

[0009] The technical solution adopted is as follows:

[0010] A hydroxyl-terminated low molecular weight polyphenylene ether, wherein the number average molecular weight of the hydroxyl-terminated low molecular weight polyphenylene ether is 500-5000.

[0011] The double-hydroxyl-terminated low molecular weight polyphenylene ether is polymerized from monomers of formula (1) and formula (2);

[0012]

[0013] Among them, B1, B2, and B3 are each independently selected from hydrogen, halogen atoms, substituted or unsubstituted C1-C8 alkyl groups, and substituted or unsubstituted C6-C4 alkyl groups. 30 Aromatic group;

[0014] R is any one of covalent bond, oxygen atom, sulfur atom, carbonyl group, sulfone group, sulfoxide group, amino group, substituted or unsubstituted C1-C8 alkylene group;

[0015] Q1, Q2, and Q3 are each independently selected from hydrogen, halogen atoms, substituted or unsubstituted C1-C8 alkyl groups, substituted or unsubstituted C1-C8 alkyl groups. 10 Alkoxy, substituted or unsubstituted C6-C 30 Aromatic group.

[0016] Furthermore, the monomer of formula (1) is 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane and / or 2,2',3,3',5,5'-hexamethyl-4,4'-dihydroxybiphenyl.

[0017] Furthermore, the monomer of formula (2) is 2,6-dimethylphenol and / or 2,3,6-trimethylphenol.

[0018] Furthermore, the molar ratio of the monomer of formula (1) to the monomer of formula (2) is 1:2-40, preferably 1:4-35, and more preferably 1:10-30.

[0019] This invention also provides a method for synthesizing the above-mentioned hydroxyl-terminated low molecular weight polyphenylene ether:

[0020] The monomer of formula (1) and oxygen-containing gas react in a solvent under the action of a catalyst to generate a diphenol radical, which is then oxidatively copolymerized with the monomer of formula (2).

[0021] Furthermore, the catalyst is a metal salt-organic amine complex.

[0022] Furthermore, the metal salt is at least one of the following: metal sulfate, halide, nitrate, and phosphate.

[0023] Furthermore, the metal is at least one of copper, manganese, and cobalt.

[0024] Furthermore, the organic amine is C2-C. 10 Aliphatic monoamines and / or C2-C 10 Aliphatic diamines.

[0025] Furthermore, the temperature of the synthesis reaction is controlled between 20-50℃.

[0026] The beneficial effects of this invention are:

[0027] This invention provides a low molecular weight polyphenylene ether with hydroxyl-terminated ends and its synthesis method. The polyphenylene ether has a number average molecular weight of 500-5000 and Mw / Mn≤1.10, indicating that the prepared polyphenylene ether has high purity and good processing performance, making it an ideal material for the electronics and electrical appliance industry. The synthesis method provided by this invention ensures that the raw materials react completely without residue, effectively avoiding the harm to humans and the environment caused by unreacted monophenols and / or diphenols, while also reducing production costs. Attached Figure Description

[0028] Figure 1 The 1H NMR spectrum of the low molecular weight polyphenylene ether with hydroxyl-terminated ends prepared in Example 1 of this invention. Detailed Implementation

[0029] Unless otherwise specified in the examples, the conditions were performed under standard conditions or as recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products. Techniques not mentioned in this invention refer to existing technologies. Unless otherwise specified, the following examples and comparative examples are parallel experiments, using the same processing steps and parameters.

[0030] A hydroxyl-terminated low molecular weight polyphenylene ether, characterized in that the number average molecular weight of the hydroxyl-terminated low molecular weight polyphenylene ether is 500-5000.

[0031] The double-hydroxyl-terminated low molecular weight polyphenylene ether is polymerized from monomers of formula (1) and formula (2);

[0032]

[0033] Among them, B1, B2, and B3 are each independently selected from hydrogen, halogen atoms, substituted or unsubstituted C1-C8 alkyl groups, and substituted or unsubstituted C6-C4 alkyl groups. 30 Aromatic group;

[0034] R is any one of covalent bond, oxygen atom, sulfur atom, carbonyl group, sulfone group, sulfoxide group, amino group, substituted or unsubstituted C1-C8 alkylene group;

[0035] Q1, Q2, and Q3 are each independently selected from hydrogen, halogen atoms, substituted or unsubstituted C1-C8 alkyl groups, substituted or unsubstituted C1-C8 alkyl groups. 10 Alkoxy, substituted or unsubstituted C6-C 30 Aromatic group.

[0036] The monomers of formula (1) include, but are not limited to, 1,1'-bis(3,5-dimethyl-4-hydroxyphenyl)methane, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)ethane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)butane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)pentane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)hexane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)heptane, and 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)pentane. Methyl-4-hydroxyphenyl)octane, bis(3,5-dichloro-4-hydroxyphenyl)methane, 1,1-bis(3,5-dichloro-4-hydroxyphenyl)ethane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)propane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)butane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)pentane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)hexane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)heptane, 2,2-bis(3,5-dichloro-4-hydroxyphenyl)octane, bis(3,5-dichloromethyl-4-hydroxyphenyl)methane, 1,1-bis(3,5-dichloromethyl-4-hydroxyphenyl)ethane, 2,2-bis(3,5-dichloromethyl-4-hydroxyphenyl)propane, (3,5-dichloromethyl-4-hydroxyphenyl)butane, (3,5-dichloromethyl-4-hydroxyphenyl)pentane, (3,5-dichloromethyl-4-hydroxyphenyl)hexane, (3,5-dichloromethyl-4-hydroxyphenyl)heptane, (3,5-dichloromethyl-4-hydroxyphenyl)octane, 2,2-bis(3,5-diphenyl-4-hydroxyphenyl) Propane, 3,3',5,5'-tetramethyl-4,4'-dihydroxybenzophenone, 3,3',5,5'-tetrachloro-4,4'-dihydroxybenzophenone, 3,3',5,5'-tetrachloromethyl-4,4'-dihydroxybenzophenone, 3,3',5,5'-tetramethyl-bisphenol sulfone, 3,3',5,5'-tetramethyl-bisphenol sulfoxide, 3,3',5,5'-tetramethyl-bisphenol sulfide, 3,3',5,5'-tetramethyl-4,4'-biphenol, 2,2',3,3',5,5'-hexamethyl-4,4'-biphenol, etc. Preferred ingredients include 1,1'-bis(3,5-dimethyl-4-hydroxyphenyl)methane, 1,1-bis(3,5-dimethyl-4-hydroxyphenyl)ethane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 3,3',5,5'-tetramethyl-4,4'-biphenol, and 2,2',3,3',5,5'-hexamethyl-4,4'-biphenol, with 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane and 2,2',3,3',5,5'-hexamethyl-4,4'-biphenol being more preferred.

[0037] The monomers of formula (2) include, but are not limited to, 2,6-dimethylphenol, 2,6-diethylphenol, 2,6-dipropylphenol, 2,6-diisopropylphenol, 2,6-dibutylphenol, 2,6-diisobutylphenol, 2,6-dichloroethylphenol, 2,6-dibromoethylphenol, 2,6-di(2-chloropropyl)phenol, 2,6-di(2-bromopropyl)phenol, 2,6-di(2-chlorobutyl)phenol, 2,6-dimethoxyphenol, 2,6-diethoxyphenol, 2-methyl-6-ethylphenol, 2-methyl-6-propylphenol, 2-methyl-6-isopropylphenol, 2-methyl-6-butylphenol, 2-methyl-6-isobutylphenol, 2-methyl-6-isobutylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-propyl ...ethylphenol, 2-methyl-6-propylphenol, 2-methyl-6-isobutylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-isobutylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-isobutylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-isobutylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-ethylphenol, 2-methyl-6-isobutylphenol, 2 2,3,6-trisubstituted phenols include, but are not limited to, 2,3,6-trimethylphenol, 2,3,6-triethylphenol, 2,3,6-tripropylphenol, 2,3,6-triisopropylphenol, 2,3,6-tributylphenol, 2,3,6-triisobutylphenol, 2,6-dimethyl-3-ethylphenol, 2,6-dimethyl-3-propylphenol, 2,6-dimethyl-3-isopropylphenol, 2,6-dimethyl-3-butylphenol, 2,6-dimethyl-3-isobutylphenol, 2,6-dimethyl-3-chloroethylphenol, 2,3,6-trimethoxyphenol, and 2,6-dimethyl-3-methoxyphenol. Preferably, it is 2,6-dimethylphenol, 2,6-diethylphenol, 2,3,6-trimethylphenol, or 2,3,6-triethylphenol. More preferably, it is 2,6-dimethylphenol and 2,3,6-trimethylphenol.

[0038] In one embodiment, the monomer of formula (1) is preferably 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane and / or 2,2',3,3',5,5'-hexamethyl-4,4'-dihydroxybiphenyl.

[0039] In one embodiment, the monomer of formula (2) is 2,6-dimethylphenol and / or 2,3,6-trimethylphenol.

[0040] In one embodiment, the molar ratio of the monomer of formula (1) to the monomer of formula (2) is 1:2-40. When the molar ratio of the monomer of formula (1) to the monomer of formula (2) is less than this range, the resulting copolymer is not easy to separate from the solvent. When the molar ratio of the monomer of formula (1) to the monomer of formula (2) is greater than this range, the molecular weight of the polymer is difficult to control, and no matter how the polymerization conditions are changed, the proportion of single-terminated hydroxyl polyphenylene ether (homopolymer of monomer of formula (2)) in the polymer becomes unacceptable.

[0041] In one embodiment, the molar ratio of monomer of formula (1) to monomer of formula (2) is preferably 1:4-35, more preferably 1:10-30.

[0042] This invention also provides a method for synthesizing the above-mentioned hydroxyl-terminated low molecular weight polyphenylene ether:

[0043] The monomer of formula (1) and oxygen-containing gas react in a solvent under the action of a catalyst to generate a diphenol radical, which is then oxidatively copolymerized with the monomer of formula (2).

[0044] The oxygen-containing gas can be oxygen and / or a mixture of oxygen and other inert gases, preferably with an oxygen concentration greater than 90 vol%, more preferably greater than 95 vol%. The total amount of oxygen introduced is not strict, but for the sake of reaction yield, the amount of oxygen introduced must be sufficient to convert all the monomers of formula (1) added to the reactor into diphenol radicals. However, excessive oxygen is not advisable, as it will not only increase production costs but also increase the risks during production.

[0045] The catalyst specifically refers to a metal salt-organic amine complex. The metal can be at least one metal such as copper, manganese, or cobalt, or a mixture thereof. The valence state of the metal is not strict and can be monovalent, divalent, trivalent, etc. The form of the metal salt is also not strict and can be sulfate, halide, nitrate, phosphate, carbonate, etc. Among the above metals, copper is preferred, and the forms include, but are not limited to, copper oxide, cuprous oxide, copper sulfate, cuprous sulfate, copper chloride, cuprous chloride, copper bromide, cuprous bromide, copper iodide, cuprous iodide, copper nitrate, cuprous nitrate, copper carbonate, cuprous carbonate, etc. The preferred copper salts are copper halides and cuprous halides. The copper salts can be commercially available products or can be generated by reacting copper oxide salts with haloacids. The amount of metal salt used is not strict, but less metal salt will reduce production costs. Generally, 0.01-2 moles of metal salt are added per 100 moles of monomer of formula (1), preferably 0.05-0.5 moles of metal salt.

[0046] Organic amines are C2-C 10 Aliphatic monoamines and / or C2-C 10 Aliphatic diamines;

[0047] The monoamine can be a primary monoamine, a secondary monoamine, a tertiary monoamine, or a mixture of two of them. Primary monoamines include, but are not limited to, n-propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine, n-pentylamine, and n-hexylamine. Secondary monoamines include, but are not limited to, dimethylamine, di-n-propylamine, di-n-butylamine, diisopropylamine, di-tert-butylamine, dipentylamine, and di-n-hexylamine. Tertiary monoamines include, but are not limited to, triethylamine, tripropylamine, tri-n-butylamine, dimethyl-n-butylamine, dimethyl-n-pentylamine, and diethyl-n-butylamine.

[0048] The aforementioned diamines specifically refer to alkylene diamines, where alkylene includes ethylene and propylene and / or branched ethylene and propylene. These diamines include, but are not limited to, ethylenediamine, propylenediamine, tetramethylethylenediamine, tetramethylpropylenediamine, N,N'-dimethylethylenediamine, N,N'-dimethylpropylenediamine, N,N'-diethylethylenediamine, N,N'-diethylpropylenediamine, N,N'-diethylpropylenediamine, N,N'-diisopropylethylenediamine, N,N'-diisopropylpropylenediamine, N,N'-di-n-butylethylenediamine, and N,N'-di-n-butylpropylenediamine. Diamines, N,N'-diisobutylethylenediamine, N,N'-diisobutylpropylenediamine, N,N'-di-tert-butylethylenediamine, N,N'-di-tert-butylpropylenediamine, N,N,N',N'-tetramethyl-1,3-diamino-1-methylpropane, N,N,N',N'-tetramethyl-1,3-diamino-1-ethylpropane, N,N,N',N'-tetramethyl-1,2-diamino-1-methylethane, N,N,N',N'-tetramethyl-1,2-diamino-1-ethylethane, etc.

[0049] The amount of organic amine used is not strict. Generally, 0.1-100 moles of nitrogen atoms are added relative to 1 mole of metal atoms, preferably 0.5-50 moles of nitrogen atoms, and more preferably 1-10 moles of nitrogen atoms.

[0050] To ensure that the monomer of formula (1) reacts with oxygen-containing gas to generate diphenol radicals, the addition of a catalyst is crucial. Without a catalyst, depending on the structure of the diphenol, the diphenol and oxygen-containing gas either do not react or generate quinone byproducts. However, in the presence of a catalyst, the diphenol and oxygen-containing gas mainly generate diphenol radicals.

[0051] The temperature of the synthesis reaction refers to the temperature at which the monomer and oxygen-containing gas generate diphenol free radicals and the temperature of oxidative copolymerization. The temperature is usually selected between 20-50℃. When the temperature is too high, the proportion of reaction byproducts increases; when the temperature is too low, the reaction proceeds slowly and the reaction efficiency is low, thereby increasing the production cost.

[0052] Example 1:

[0053] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 160 kg of toluene and 15 kg of [unspecified substance] were added. 2,2-Bis(3,5-dimethyl-4-hydroxyphenyl)propane (TMBPA), 18g copper chloride dihydrate, 18.2g di-tert-butylethylenediamine, 136g di-n-butylamine, and 320g dimethyl-n-butylamine were used. After all TMBPA was dissolved, oxygen was introduced at a rate of 60 L / min, and the temperature inside the reactor was maintained at 35°C. After all TMBPA was converted into TMBPA free radicals, 225kg of toluene solution containing 65kg of 2,6-dimethylphenol (DMP) was continuously pumped into the reactor for 120min, while maintaining the temperature inside the reactor at 35°C-40°C. After polymerization was completed, oxygen was stopped, and 20kg of aqueous solution containing 142g of disodium ethylenediaminetetraacetate (EDTA-2Na) was added to the reactor and stirred continuously for 20min to terminate the reaction. The solution inside the reactor was heated to 60°C and maintained for 1h with continuous stirring. After the reaction was completed, the organic layer and the aqueous layer were separated, and the organic layer was washed with water. The resulting organic layer was then subjected to flash evaporation to remove some of the toluene. 500 kg of methanol was added to the solution under continuous stirring to precipitate the dihydroxyl-terminated low molecular weight polyphenylene ether. The precipitate was then separated by centrifugation and dried to obtain the product. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of this dihydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0054] Example 2:

[0055] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 68.6 kg of toluene, 15 kg of TMBPA, 90 g of copper chloride dihydrate, 91 g of di-tert-butylethylenediamine, 100 g of di-n-butylamine, and 300 g of dimethyl-n-butylamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 35°C. After all the TMBPA was converted into free radicals, 87.9 kg of toluene solution containing 19.3 kg of DMP was added in one go while continuously stirring, and the temperature inside the reactor was maintained at 35°C-40°C. After polymerization was completed, oxygen was stopped, and 20 kg of aqueous solution containing 710 g of EDTA-2Na was added to the reactor, and the mixture was stirred continuously for 20 min to terminate the reaction. The solution in the reactor was heated to 60°C and maintained for 1 h with continuous stirring. After the reaction was completed, the organic layer and the aqueous layer were separated, and the organic layer was washed with water. The organic layer obtained in this way is subjected to flash evaporation to remove part of the toluene, and then the remaining solvent is removed by a screw de-volatile extruder to obtain the product. The number average molecular weight, weight average molecular weight, molecular weight distribution and residual raw material values ​​of this dihydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0056] Example 3:

[0057] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 287.6 kg of toluene, 15 kg of TMBPA, 5 g of copper bromide, and 0.65 g of tetramethylethylenediamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 20 L / min, and the temperature inside the reactor was maintained at 25 °C. After all the TMBPA was converted into free radicals, 416.4 kg of a toluene solution containing 128.8 kg of DMP was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30 °C-35 °C. After polymerization was completed, oxygen was stopped, and 10 kg of an aqueous solution containing 30 g of EDTA-2Na was added to the reactor, and the mixture was stirred continuously for 20 min to terminate the reaction. The solution inside the reactor was heated to 60 °C and maintained for 1 h with continuous stirring. After the reaction was completed, the organic layer and the aqueous layer were separated, and the organic layer was washed with water. The organic layer obtained in this way was partially detoxified by flash evaporation. Then, 500 kg of methanol was added to the solution to precipitate the hydroxyl-terminated low molecular weight polyphenylene ether. After centrifugation and drying, the product was obtained. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of the hydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0058] Example 4:

[0059] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 416 kg of methanol, 15 kg of TMBPA, 180 g of copper chloride dihydrate, 60 g of tetramethylethylenediamine, 270 g of di-n-butylamine, and 210 g of dimethyl-n-butylamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 30 °C. After all the TMBPA was converted into free radicals, 609 kg of methanol solution containing 193 kg of DMP was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30 °C-35 °C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, the oxygen supply was stopped, and 3 kg of aqueous solution containing 1.5 kg of EDTA-2Na was added to the reactor, and the mixture was stirred continuously for 20 min to terminate the reaction. Then, hydroquinone was added little by little to the reactor until the slurry turned white, and the mixture was stirred continuously for 1 h. After the reaction was completed, the crude product of dihydroxyl-terminated low molecular weight polyphenylene ether was obtained by centrifugation. The crude product was washed with water and then centrifuged again. Finally, it was dried to obtain the final product. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of the dihydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0060] Example 5:

[0061] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 424 kg of methanol, 106 kg of butanone, 15 kg of TMBPA, 36 g of copper chloride dihydrate, 36.3 g of di-tert-butylethylenediamine, 245 g of di-n-butylamine, and 192 g of dimethyl-n-butylamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 25°C. After all the TMBPA was converted into free radicals, a solution of 250 kg of DMP, 424 kg of methanol, and 106 kg of butanone was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 25°C-30°C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, the oxygen supply was stopped, and a solution containing 284 g of [unspecified substance] was added to the reactor. 3 kg of an aqueous solution of EDTA-2Na was added and stirred continuously for 20 min to terminate the reaction. Hydroquinone was then added little by little to the reactor until the slurry turned white, and this process was maintained for 1 h with continuous stirring. After the reaction was complete, the crude product of dihydroxyl-terminated low molecular weight polyphenylene ether was obtained by centrifugation. The crude product was washed with water and then centrifuged again, finally dried to obtain the final product. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of this dihydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0062] Example 6:

[0063] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 177.6 kg of methanol, 44.4 kg of butanol, 15 kg of TMBPA, 9 g of copper chloride dihydrate, 9.1 g of di-tert-butylethylenediamine, 260 g of di-n-butylamine, and 200 g of dimethyl-n-butylamine were added. After all the TMBPA was dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 30 °C. After all the TMBPA was converted into free radicals, a solution of 96 kg of DMP, 177.6 kg of methanol, and 44.4 kg of butanol was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30 °C-35 °C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, the oxygen supply was stopped, and a solution containing 71 g of [unspecified substance] was added to the reactor. 3 kg of an aqueous solution of EDTA-2Na was added and stirred continuously for 20 min to terminate the reaction. Hydroquinone was then added little by little to the reactor until the slurry turned white, and this process was maintained for 1 h with continuous stirring. After the reaction was complete, the crude product of dihydroxyl-terminated low molecular weight polyphenylene ether was obtained by centrifugation. The crude product was washed with water and then centrifuged again, finally dried to obtain the final product. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of this dihydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0064] Example 7:

[0065] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 280 kg of methanol, 70 kg of toluene, 15 kg of TMBPA, 6 g of copper bromide, and 15.6 g of tetramethylethylenediamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 20 L / min, and the temperature inside the reactor was maintained at 25 °C. After all the TMBPA was converted into free radicals, a solution of 160 kg of DMP, 280 kg of methanol, and 70 kg of toluene was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30 °C-35 °C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, the oxygen supply was stopped, and 1 kg of an aqueous solution containing 36 g of EDTA-2Na was added to the reactor, and the mixture was stirred continuously for 20 min to terminate the reaction. Then, hydroquinone was added little by little to the reactor until the slurry turned white, and this was maintained for 1 h with continuous stirring. After the reaction was completed, the crude product of dihydroxyl-terminated low molecular weight polyphenylene ether was obtained by centrifugation. The crude product was washed with water and then centrifuged again. Finally, it was dried to obtain the final product. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of the dihydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0066] Example 8:

[0067] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 93.8 kg of methanol, 40.2 kg of toluene, 15 kg of TMBPA, 59 g of copper bromide, and 15.3 g of tetramethylethylenediamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 30 °C. After all the TMBPA was converted into free radicals, a solution of 52 kg of DMP, 93.8 kg of methanol, and 40.2 kg of toluene was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30 °C-35 °C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, the oxygen supply was stopped, and 2 kg of an aqueous solution containing 355 g of EDTA-2Na was added to the reactor, and the mixture was stirred continuously for 20 min to terminate the reaction. Then, hydroquinone was added little by little to the reactor until the slurry turned white, and this was maintained for 1 h with continuous stirring. After the reaction was completed, the crude product of dihydroxyl-terminated low molecular weight polyphenylene ether was obtained by centrifugation. The crude product was washed with water and then centrifuged again. Finally, it was dried to obtain the final product. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of the dihydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0068] Example 9:

[0069] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 128 kg of toluene, 32 kg of methanol, 15 kg of TMBPA, 6 g of copper chloride dihydrate, 6.1 g of di-tert-butylethylenediamine, 9.1 g of di-n-butylamine, and 7.1 g of dimethyl-n-butylamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 60 L / min, and the temperature inside the reactor was maintained at 30 °C. After all the TMBPA was converted into free radicals, a solution of 65 kg of DMP, 128 kg of toluene, and 32 kg of methanol was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30 °C-35 °C. After polymerization was complete, oxygen was stopped, and 1 kg of an aqueous solution containing 47 g of EDTA-2Na was added to the reactor, and the mixture was stirred continuously for 20 min to terminate the reaction. The solution inside the reactor was heated to 60 °C and maintained for 1 h with continuous stirring. After the reaction was complete, the organic layer and the aqueous layer were separated, and the organic layer was washed with water. The organic layer obtained in this way was partially detoxified by flash evaporation. Then, 400 kg of methanol was added to the solution to precipitate the hydroxyl-terminated low molecular weight polyphenylene ether. After centrifugation and drying, the product was obtained. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of the hydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0070] Comparative Example 1:

[0071] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 320 kg of toluene, 15 kg of TMBPA, 65 kg of DMP, 18 g of copper chloride dihydrate, 18.2 g of di-tert-butylethylenediamine, 130 g of di-n-butylamine, and 300 g of dimethyl-n-butylamine were added. After all the raw materials were dissolved, oxygen was introduced at a rate of 60 L / min, and the temperature inside the reactor was maintained at 35℃-40℃. After polymerization was completed, the oxygen supply was stopped, and 20 kg of an aqueous solution containing 710 g of EDTA-2Na was added to the reactor. The mixture was stirred continuously for 20 min to terminate the reaction. The solution in the reactor was heated to 60℃ and maintained for 1 h with continuous stirring. After the reaction was completed, the organic layer and the aqueous layer were separated, and the organic layer was washed with water. The organic layer obtained was then flash-evaporated to remove some of the toluene. 500 kg of methanol was added to the solution to precipitate the dihydroxyl-terminated low molecular weight polyphenylene ether. The precipitate was separated by centrifugation and dried to obtain the product. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of the dihydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0072] Comparative Example 2:

[0073] In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 18g of copper chloride dihydrate, 18.2g of di-tert-butylethylenediamine, 130g of di-n-butylamine, and 300g of dimethyl-n-butylamine were added. 15kg of TMBPA and 65kg of DMP were dissolved in 320kg of toluene and continuously pumped into the reactor. Oxygen was simultaneously introduced at a rate of 60L / min, and the temperature inside the reactor was maintained at 35℃-40℃. After polymerization was complete, oxygen was stopped, and 20kg of an aqueous solution containing 710g of EDTA-2Na was added to the reactor. The mixture was stirred continuously for 20min to terminate the reaction. The solution in the reactor was heated to 60℃ and maintained for 1 hour with continuous stirring. After the reaction was complete, the organic and aqueous layers were separated, and the organic layer was washed with water. The resulting organic layer was then flash-evaporated to remove some of the toluene. 500kg of methanol was added to the solution to precipitate the dihydroxyl-terminated low molecular weight polyphenylene ether. The precipitate was separated by centrifugation and dried to obtain the final product. The number-average molecular weight, weight-average molecular weight, molecular weight distribution, and residual raw material values ​​of the dihydroxyl-terminated low molecular weight polyphenylene ether are listed in Table 1.

[0074] Performance testing:

[0075] (1) Determination of molecular weight

[0076] Number-average molecular weight (Mn), weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) were determined using gel permeation chromatography (GPC). A Shimadzu LC-20A column was used, with polystyrene as the standard. KF-803, KF-804, and KF-G columns were selected, and the tests were performed in toluene solution at 30°C using a differential refractive index detector.

[0077] (2) Determination of unreacted monomers in the reaction solution

[0078] The concentrations of unreacted monomers (monophenols and diphenols) in the reaction solution were measured using gas chromatography-mass spectrometry (GC-MS). The Shimadzu GC-MS system consisted of an autosampler, a Shimadzu GC-2010, and a QP2010 Plus. 0.5 mL of the reaction solution was dissolved in 20 mL of chloroform to prepare a sample solution, which was then injected into the GC via the autosampler. The inlet temperature was set at 250 °C, and the oven temperature was increased from 70 °C to 270 °C at a rate of 10 °C / min and held for 25 minutes. Toluene was used as an internal standard, and the detection parameters were 107 AMU for 2,6-dimethylphenol and 269 AMU for 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane at 77 AMU (atomic mass units). Under the conditions listed above, the residence times for toluene, 2,6-dimethylphenol, and 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane were 2.69, 6.92, and 19.89 minutes, respectively. This method was corrected using a series of monomer standard solutions containing different concentrations.

[0079] (3) 1 HNMR testing

[0080] Using Bruke AVANCE III 400M 1 HNMR test.

[0081] Table 1:

[0082] Mn Mw Mw / Mn Residual TMBPA Residual DMP Example 1 1540 2630 1.07 Not detected Not detected Example 2 680 1390 1.10 Not detected Not detected Example 3 2650 4300 1.06 Not detected Not detected Example 4 3830 5700 1.05 Not detected Not detected Example 5 4970 6460 1.03 Not detected Not detected Example 6 2050 3260 1.06 Not detected Not detected Example 7 3200 4870 1.05 Not detected Not detected Example 8 1280 2470 1.09 Not detected Not detected Example 9 1500 2550 1.07 Not detected Not detected Comparative Example 1 2100 4050 1.92 1.3% TMBPA did not react. 1.5% DMP did not react Comparative Example 2 1740 2750 1.65 5.2% TMBPA did not react. 0.8% DMP did not react.

[0083] As shown in Table 1 above, the number-average molecular weight distribution of the polyphenylene ether prepared in this invention is in the range of 500-5000, and Mw / Mn≤1.10, indicating that the prepared polyphenylene ether has high purity.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing a low molecular weight polyphenylene ether with dual hydroxyl terminals, characterized in that, In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 160 kg of toluene, 15 kg of 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 18 g of copper chloride dihydrate, 18.2 g of di-tert-butylethylenediamine, 136 g of di-n-butylamine, and 320 g of dimethyl-n-butylamine were added. After all TMBPA was dissolved, oxygen was introduced at a rate of 60 L / min, and the temperature inside the reactor was maintained at 35 °C. After all TMBPA was converted into TMBPA free radicals, 225 kg of toluene solution containing 65 kg of 2,6-dimethylphenol was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 35 °C. ℃-40℃; after polymerization is complete, stop the oxygen supply, add 20kg of aqueous solution containing 142g of disodium ethylenediaminetetraacetate to the reactor, and stir continuously for 20min to terminate the reaction; heat the solution in the reactor to 60℃ and maintain the temperature for 1h with continuous stirring. After the reaction is complete, separate the organic layer and the aqueous layer, and wash the organic layer with water. After removing some toluene from the organic layer obtained in this way by flash evaporation, add 500kg of methanol to the solution with continuous stirring to precipitate the low molecular weight polyphenylene ether with double hydroxyl groups. Separate by centrifugation and dry to obtain the product.

2. A method for synthesizing a low molecular weight polyphenylene ether with dual hydroxyl terminals, characterized in that, In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 68.6 kg of toluene, 15 kg of TMBPA, 90 g of copper chloride dihydrate, 91 g of di-tert-butylethylenediamine, 100 g of di-n-butylamine, and 300 g of dimethyl-n-butylamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 35°C. After all the TMBPA was converted into free radicals, 87.9 kg of a toluene solution containing 19.3 kg of DMP was added in one go with continuous stirring, and the temperature inside the reactor was maintained at 35°C-40°C. After polymerization was completed, the oxygen supply was stopped, and a solution containing 710 g of DMP was added to the reactor. 20 kg of EDTA-2Na aqueous solution was added and stirred continuously for 20 min to terminate the reaction. The solution in the reaction vessel was heated to 60 °C and maintained for 1 h with continuous stirring. After the reaction was completed, the organic layer and the aqueous layer were separated, and the organic layer was washed with water. The organic layer obtained was then subjected to flash evaporation to remove part of the toluene, and the remaining solvent was removed by a screw de-volatile extruder to obtain the product.

3. A method for synthesizing a low molecular weight polyphenylene ether with dual hydroxyl terminals, characterized in that, In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 287.6 kg of toluene, 15 kg of TMBPA, 5 g of copper bromide, and 0.65 g of tetramethylethylenediamine were added. After the TMBPA was completely dissolved, oxygen was introduced at a rate of 20 L / min, and the temperature inside the reactor was maintained at 25 °C. After the TMBPA was completely converted into free radicals, 416.4 kg of a toluene solution containing 128.8 kg of DMP was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30 °C-35 °C. After polymerization was completed, the oxygen supply was stopped, and a solution containing 30 g of DMP was added to the reactor. 10 kg of EDTA-2Na aqueous solution was added and stirred continuously for 20 min to terminate the reaction. The solution in the reaction vessel was heated to 60 °C and maintained for 1 h with continuous stirring. After the reaction was completed, the organic layer and the aqueous layer were separated, and the organic layer was washed with water. The organic layer obtained was then flash-evaporated to remove some toluene. 500 kg of methanol was added to the solution to precipitate the low molecular weight polyphenylene ether with double hydroxyl groups. The precipitate was separated by centrifugation and dried to obtain the product.

4. A method for synthesizing a low molecular weight polyphenylene ether with dual hydroxyl terminals, characterized in that, In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 416 kg of methanol, 15 kg of TMBPA, 180 g of copper chloride dihydrate, 60 g of tetramethylethylenediamine, 270 g of di-n-butylamine, and 210 g of dimethyl-n-butylamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 30°C. After all the TMBPA was converted into free radicals, 609 kg of a methanol solution containing 193 kg of DMP was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30°C-35°C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, the oxygen supply was stopped, and 1.5 kg of a methanol solution containing 193 kg of DMP was added to the reactor. 3 kg of EDTA-2Na aqueous solution was added and stirred continuously for 20 min to terminate the reaction. Then, hydroquinone was added little by little to the reaction vessel until the slurry turned white, and stirred continuously for 1 h. After the reaction was completed, the crude product of low molecular weight polyphenylene ether with double hydroxyl ends was obtained by centrifugation. The crude product was washed with water and then separated by centrifugation. Finally, the product was obtained by drying.

5. A method for synthesizing a low molecular weight polyphenylene ether with dual hydroxyl terminals, characterized in that, In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 424 kg of methanol, 106 kg of butanone, 15 kg of TMBPA, 36 g of copper chloride dihydrate, 36.3 g of di-tert-butylethylenediamine, 245 g of di-n-butylamine, and 192 g of dimethyl-n-butylamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 25°C. After all the TMBPA was converted into free radicals, a solution of 250 kg of DMP, 424 kg of methanol, and 106 kg of butanone was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 25°C-30°C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, the oxygen supply was stopped, and a solution containing 284 g of [unspecified substance] was added to the reactor. 3 kg of EDTA-2Na aqueous solution was added and stirred continuously for 20 min to terminate the reaction. Then, hydroquinone was added little by little to the reactor until the slurry turned white, and the mixture was kept stirred continuously for 1 h. After the reaction was completed, the crude product of low molecular weight polyphenylene ether with double hydroxyl ends was obtained by centrifugation. The crude product was washed with water and then separated by centrifugation. Finally, the product was obtained by drying.

6. A method for synthesizing a low molecular weight polyphenylene ether with dual hydroxyl terminals, characterized in that, In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 177.6 kg of methanol, 44.4 kg of butanol, 15 kg of TMBPA, 9 g of copper chloride dihydrate, 9.1 g of di-tert-butylethylenediamine, 260 g of di-n-butylamine, and 200 g of dimethyl-n-butylamine were added. After all the TMBPA was dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 30 °C. After all the TMBPA was converted into free radicals, a solution of 96 kg of DMP, 177.6 kg of methanol, and 44.4 kg of butanol was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30 °C-35 °C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, the oxygen supply was stopped, and a solution containing 71 g of [unspecified substance] was added to the reactor. 3 kg of EDTA-2Na aqueous solution was added and stirred continuously for 20 min to terminate the reaction. Then, hydroquinone was added little by little to the reactor until the slurry turned white, and the mixture was kept stirred continuously for 1 h. After the reaction was completed, the crude product of low molecular weight polyphenylene ether with double hydroxyl ends was obtained by centrifugation. The crude product was washed with water and then separated by centrifugation. Finally, the product was obtained by drying.

7. A method for synthesizing a low molecular weight polyphenylene ether with dual hydroxyl terminals, characterized in that, In a jacketed reactor equipped with a stirrer, thermometer, gas inlet and top condenser, 280 kg of methanol and 70 kg of toluene, 15 kg of TMBPA, 6 g of copper bromide and 15.6 g of tetramethylethylenediamine were added. After TMBPA was completely dissolved, oxygen was introduced at a rate of 20 L / min, and the temperature inside the reactor was maintained at 25°C. After TMBPA was completely converted into free radicals, a solution of 160 kg DMP, 280 kg methanol, and 70 kg toluene was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30°C-35°C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, oxygen was stopped, and 1 kg of an aqueous solution containing 36 g EDTA-2Na was added to the reactor, and the mixture was stirred continuously for 20 min to terminate the reaction. Then, hydroquinone was added little by little to the reactor until the slurry turned white, and this was maintained for 1 h with continuous stirring. After the reaction was completed, the crude product of low molecular weight polyphenylene ether with hydroxyl-terminated ends was obtained by centrifugation. The crude product was washed with water and then separated by centrifugation again. Finally, the product was dried to obtain the final product.

8. A method for synthesizing a low molecular weight polyphenylene ether with dual hydroxyl terminals, characterized in that, In a jacketed reactor equipped with a stirrer, thermometer, gas inlet and top condenser, 93.8 kg of methanol, 40.2 kg of toluene, 15 kg of TMBPA, 59 g of copper bromide and 15.3 g of tetramethylethylenediamine were added. After TMBPA was completely dissolved, oxygen was introduced at a rate of 90 L / min, and the temperature inside the reactor was maintained at 30°C. After TMBPA was completely converted into free radicals, a solution of 52 kg DMP, 93.8 kg methanol, and 40.2 kg toluene was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30°C-35°C. As the reaction proceeded, the polymer continuously precipitated from the solution. After polymerization was completed, oxygen was stopped, and 2 kg of an aqueous solution containing 355 g EDTA-2Na was added to the reactor, and the mixture was stirred continuously for 20 min to terminate the reaction. Then, hydroquinone was added little by little to the reactor until the slurry turned white, and this was maintained for 1 h with continuous stirring. After the reaction was completed, the crude product of low molecular weight polyphenylene ether with hydroxyl-terminated ends was obtained by centrifugation. The crude product was washed with water and then separated by centrifugation again. Finally, the product was dried to obtain the final product.

9. A method for synthesizing a low molecular weight polyphenylene ether with dual hydroxyl terminals, characterized in that, In a jacketed reactor equipped with a stirrer, thermometer, gas inlet, and top condenser, 128 kg of toluene and 32 kg of methanol, 15 kg of TMBPA, 6 g of copper chloride dihydrate, 6.1 g of di-tert-butylethylenediamine, 9.1 g of di-n-butylamine, and 7.1 g of dimethyl-n-butylamine were added. After all the TMBPA dissolved, oxygen was introduced at a rate of 60 L / min, and the temperature inside the reactor was maintained at 30 °C. After all the TMBPA was converted into free radicals, a solution of 65 kg of DMP, 128 kg of toluene, and 32 kg of methanol was continuously pumped in for 120 min, while maintaining the temperature inside the reactor at 30 °C-35 °C. After polymerization was completed, the oxygen supply was stopped, and 47 g of a solution containing [unspecified substance] was added to the reactor. 1 kg of EDTA-2Na aqueous solution was added and stirred continuously for 20 min to terminate the reaction. The solution in the reaction vessel was heated to 60 °C and maintained for 1 h with continuous stirring. After the reaction was completed, the organic layer and the aqueous layer were separated, and the organic layer was washed with water. The organic layer obtained was then flash-evaporated to remove some toluene. 400 kg of methanol was added to the solution to precipitate the low molecular weight polyphenylene ether with double hydroxyl groups. The precipitate was separated by centrifugation and dried to obtain the product.

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