A preparation method and preparation system of high hydroxyl value polyphenylene ether

Abstract

The present invention provides a method and system for preparing a high-hydroxyl-value polyphenylene ether. The method comprises: mixing a dihydroxybenzene monomer, a monohydroxybenzene monomer, a catalyst, and a solvent, introducing an oxidizing gas to conduct a first-stage polymerization reaction to obtain a first-stage polymerization product; mixing the first-stage polymerization product with a monohydroxybenzene monomer, a catalyst, and a solvent, and introducing an oxidizing gas to conduct a second-stage polymerization reaction to obtain a second-stage polymerization product; performing the polymerization reaction in at least three stages; and mixing the final-stage polymerization product with a redistribution monomer to conduct a redistribution reaction to obtain the polymerization product. The method and system can inhibit the mutual polymerization of monohydroxybenzene monomers, reduce the formation of monohydroxy polyphenylene ether molecular chains during the reaction, thereby reducing the proportion of monohydroxy molecules in the prepared polyphenylene ether material and increasing the proportion of dihydroxy polyphenylene ether molecules.

Description

Technical Field

[0001] The present invention belongs to the field of polymer synthesis, and relates to a preparation method and a preparation system of polyphenylene ether, in particular to a preparation method and a preparation system of high hydroxyl value polyphenylene ether. Background Art

[0002] Polyphenylene ether (PPE) is one of the five most common engineering plastics. It possesses excellent mechanical properties, electrical insulation, heat resistance, flame retardancy, water resistance, and chemical stability, making it the preferred resin matrix for high-performance copper-clad laminates. However, conventional PPE contains few active functional groups in its molecular structure and exhibits low polarity. This leads to poor compatibility with other resins, such as epoxy resins, negatively impacting the composite's mechanical, heat resistance, and dielectric properties. Therefore, PPE resins need to be modified to form cross-linked thermosetting resins, enhancing their solder resistance, solvent resistance, and dielectric properties.

[0003] At present, there are two main improvement methods: one is to introduce other high-performance thermosetting resins through blending modification or interpenetration technology to form a compatible resin system; the other is to introduce cross-linkable active groups into the molecular structure of polyphenylene ether to modify polyphenylene ether into a thermosetting resin.

[0004] A method for preparing a thermosetting polyphenylene ether resin involves an oxidative copolymerization-condensation reaction between 2,6-dimethylphenol and tetramethylbisphenol A to produce a low-molecular-weight, double-terminated hydroxyl polyphenylene ether. The hydroxyl groups at the ends of the polyphenylene ether molecular chain are then subjected to various chemical reactions, depending on the intended application, to produce a series of modified polyphenylene ether resins suitable for applications in high-frequency, high-speed electronics. The polyphenylene ether molecules obtained from this polymerization process include two types: molecular chains containing tetramethylbisphenol A molecules with double-terminated hydroxyl groups, and molecular chains without tetramethylbisphenol A molecules with only single hydroxyl groups. The former, after modification with methacrylic anhydride or other agents, forms a structure with double-terminated olefinic groups. This structure can then be thermally cured to form a cross-linked thermosetting material. The latter, however, only forms chain-like molecules after modification and curing, without providing thermosetting properties.

[0005] Therefore, the content of terminal hydroxyl groups in polyphenylene ether molecules has a significant impact on the properties of the subsequent thermosetting resin prepared. Reducing the proportion of monohydroxyl molecules in the polyphenylene ether product can significantly improve the properties of the material after polyphenylene ether is processed by thermosetting. Summary of the Invention

[0006] In order to solve the technical problems existing in the prior art, the present invention provides a preparation method and preparation system for high-hydroxyl-value polyphenylene ether. The preparation method and preparation system can inhibit the mutual polymerization of monohydroxybenzene monomers and reduce the generation of monohydroxy polyphenylene ether molecular chains during the reaction process, thereby reducing the proportion of monohydroxy molecules in the prepared polyphenylene ether material and increasing the proportion of dihydroxy polyphenylene ether molecules.

[0007] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0008] One of the objects of the present invention is to provide a method for preparing a high hydroxyl value polyphenylene ether, the preparation method comprising:

[0009] After mixing a dihydroxybenzene monomer, a monohydroxybenzene monomer, a catalyst and a solvent, an oxidizing gas is introduced to carry out a first stage polymerization reaction to obtain a first stage polymerization product;

[0010] The first stage polymerization product is mixed with a monohydroxybenzene monomer, a catalyst and a solvent, and then an oxidizing gas is introduced to carry out a second stage polymerization reaction to obtain a second stage polymerization product;

[0011] The polymerization reaction is carried out at least 3 stages;

[0012] The final stage polymerization product is mixed with a redistribution monomer to undergo a redistribution reaction to obtain the polymerization product.

[0013] As a preferred technical solution of the present invention, the dihydroxybenzene monomer includes tetramethyl bisphenol F or tetramethyl bisphenol A.

[0014] Preferably, the monohydroxybenzene monomer includes 2,6-dimethylphenol.

[0015] As a preferred technical solution of the present invention, the catalyst includes a main catalyst and a catalyst promoter.

[0016] Preferably, the catalyst is a combination of a metal salt and a ligand, wherein the metal salt comprises any one of cuprous chloride, cuprous bromide, cupric chloride or cupric bromide, or a combination of at least two thereof.

[0017] Preferably, the ligand includes any one or a combination of at least two of dimethylamine, diethylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, diethylmethylamine, dimethylpropylamine, N,N-dimethyl-n-butylamine, N,N-di-tert-butylethylenediamine or N,N-diisopropylethylenediamine, preferably N,N-di-tert-butylethylenediamine.

[0018] Preferably, the catalyst co-agent comprises an azodicarboxylate.

[0019] Preferably, the azodicarboxylic acid ester includes any one of diethyl azodicarboxylate, diisopropyl azodicarboxylate or tert-butyl azodicarboxylate, or a combination of at least two thereof, and more preferably diisopropyl azodicarboxylate.

[0020] As a preferred technical solution of the present invention, the molar ratio of monohydroxybenzene monomer to dihydroxybenzene monomer is 6~39:1.

[0021] As a preferred technical solution of the present invention, the reaction temperature of each stage of the reaction device is maintained by a heating device of the external circulation pipeline, and the reaction temperature is 30~70℃.

[0022] Preferably, the reaction time of each stage of the reaction device is 40 to 90 minutes.

[0023] As a preferred technical solution of the present invention, the redistribution monomer includes a dihydroxy compound.

[0024] Preferably, the dihydroxy compound includes 3,3,5,5-tetramethyl-4,4-biphenyldiphenol.

[0025] As a preferred technical solution of the present invention, the molar ratio of the redistribution monomer to the dihydroxybenzene monomer is 0.1-4:1.

[0026] A second object of the present invention is to provide a system for preparing high hydroxyl value polyphenylene ether, the system comprising:

[0027] At least three stages of reaction devices are connected in series, and the raw material inlets of the reaction devices at each stage are independently connected to the monohydroxybenzene monomer feed pipeline; the first stage reaction device is provided with a dihydroxybenzene monomer feed inlet, and the dihydroxybenzene monomer feed inlet is connected to the dihydroxybenzene monomer feed pipeline; the oxidizing gas inlets of the reaction devices at each stage are independently connected to the oxidizing gas feed pipeline;

[0028] Each stage of the reaction device is independently provided with an external circulation pipeline, and the external circulation pipeline of each stage of the reaction device is provided with a discharge port, which is independently connected to the raw material inlet of the next stage of the reaction device. The discharge port of the circulation pipeline of the last stage of the reaction device is connected to the feed port of the redistribution reaction device, and the feed port of the redistribution reaction device is connected to the redistribution monomer feed pipeline.

[0029] As a preferred technical solution of the present invention, the external circulation pipelines of each stage of the reaction device are independently provided with heat exchange devices.

[0030] As a preferred technical solution of the present invention, the redistribution reaction device is provided with a discharge port, which is connected to the post-processing section.

[0031] Compared with the prior art, the present invention has at least the following beneficial effects:

[0032] (1) The present invention provides a method and system for preparing a high-hydroxyl-value polyphenylene ether, which can inhibit the mutual polymerization of monohydroxybenzene monomers, reduce the generation of monohydroxy polyphenylene ether molecular chains during the reaction process, and thus reduce the proportion of monohydroxy molecules in the prepared polyphenylene ether material;

[0033] (2) The present invention provides a method and system for preparing high-hydroxyl-value polyphenylene ether. The mass proportion of dihydroxy polyphenylene ether molecules in the polyphenylene ether prepared by the method and system is more than 97%, and the product of the hydroxyl value and the number average molecular weight of the polyphenylene ether reaches 109.2 g KOH / mol (1.95 mol KOH / mol, the molecular weight of the polyphenylene ether is 500-5000 g / mol). BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a schematic structural diagram of the preparation system of high hydroxyl value polyphenylene ether provided by the present invention.

[0035] The present invention is further described in detail below. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims. DETAILED DESCRIPTION

[0036] The technical solution of this application is further explained below through specific implementation methods.

[0037] A specific embodiment of the present invention provides a method for preparing high hydroxyl value polyphenylene ether, the preparation method comprising:

[0038] After mixing a dihydroxybenzene monomer, a monohydroxybenzene monomer, a catalyst and a solvent, an oxidizing gas is introduced to carry out a first stage polymerization reaction to obtain a first stage polymerization product;

[0039] The first stage polymerization product is mixed with a monohydroxybenzene monomer, a catalyst and a solvent, and then an oxidizing gas is introduced to carry out a second stage polymerization reaction to obtain a second stage polymerization product;

[0040] The polymerization reaction is carried out at least 3 stages;

[0041] The final stage polymerization product is mixed with a redistribution monomer to undergo a redistribution reaction to obtain the polymerization product.

[0042] In the present invention, the polymerization reaction is carried out in multiple stages in series, which enables continuous production compared to the single-stage reaction in traditional production processes. The product of the previous stage reaction is transferred to the next stage polymerization reaction, which receives the product of the previous stage polymerization reaction and continues the polymerization reaction of the current stage. As each stage polymerization reaction proceeds, the high-molecular-weight polyphenylene ether product is continuously removed from the reaction system of the current stage, resulting in a smaller molecular weight distribution of the product polyphenylene ether. At the same time, by limiting the content of the polymerization monomers in each stage polymerization reaction, the reaction between the polymerization monomers to form monohydroxy polyphenylene ether molecular chains is reduced, thereby increasing the hydroxyl functionality of the product.

[0043] In one embodiment of the present invention, the bishydroxybenzene monomer includes tetramethyl bisphenol F or tetramethyl bisphenol A. The monohydroxybenzene monomer includes 2,6-dimethylphenol.

[0044] In one embodiment of the present invention, a solvent is added to each stage of the reaction apparatus to dissolve the reaction materials and form a homogeneous reaction. The solvent can be an aromatic hydrocarbon such as benzene, toluene, ethylbenzene, and xylene; or a halogenated hydrocarbon such as chloroform, dichloroethane, trichloroethane, and chlorobenzene; preferably, toluene.

[0045] In one embodiment of the present invention, the capacity of the solvent is 2 to 8 times, preferably 4 times, the mass of the monohydroxybenzene monomer or the dihydroxybenzene monomer.

[0046] In one embodiment of the present invention, the catalyst includes a main catalyst and a catalyst promoter.

[0047] In one embodiment of the present invention, the catalyst includes a copper-based catalyst and a ligand. The copper-based catalyst includes cuprous compounds such as cuprous chloride, cuprous bromide, cuprous nitrate, and cuprous sulfate; copper compounds such as cupric chloride, cupric bromide, cupric nitrate, and cupric sulfate; or copper salts obtained by reacting copper oxide or cuprous oxide with a hydrohalic acid; preferably cuprous chloride, cuprous bromide, cupric chloride, and cupric bromide.

[0048] In one embodiment of the present invention, the amount of the copper-based catalyst added is 0.001 to 0.3 mol per mole of the bishydroxybenzene monomer, calculated as copper element.

[0049] In one embodiment of the present invention, the ligand is preferably an amine ligand, such as a secondary alkylene diamine, a tertiary amine, and a monoamine. One or more amine ligands may be used in combination. Monoamines include dimethylamine and diethylamine; secondary alkylene diamines include N,N-di-tert-butylethylenediamine and / or N,N-diisopropylethylenediamine; and tertiary amines include trimethylamine, triethylamine, tripropylamine, tributylamine, diethylmethylamine, dimethylpropylamine, or N,N-dimethyl-n-butylamine; preferably, N,N-di-tert-butylethylenediamine.

[0050] In one embodiment of the present invention, the amount of the ligand used is 2 to 10 mol per mole of homologous catalyst.

[0051] In one embodiment of the present invention, the catalyst adjuvant includes an azodicarboxylate, and the azodicarboxylate includes any one or a combination of at least two of diethyl azodicarboxylate (DEAD), diisopropyl azodicarboxylate (DIAD) or tert-butyl azodicarboxylate (DBAD), and is more preferably diisopropyl azodicarboxylate.

[0052] In one embodiment of the present invention, the amount of the catalyst adjuvant used is 0.05-2 mol / mol copper salt.

[0053] In the present invention, the catalyst auxiliary azodicarboxylate, due to its electron-rich structure, participates in the coordination structure of the copper amine catalyst to form a hydrazine free radical stabilized by copper coordination, thereby increasing the overall activity of the catalyst. Among the various azodicarboxylate esters, DIAD has the advantages of both high activity and low price.

[0054] In one embodiment of the present invention, the oxidizing gas is preferably oxygen, wherein the volume concentration of oxygen may be 21 to 100%, preferably 90 to 100%.

[0055] In one embodiment of the present invention, the oxygen introduction rate per hour is 0.6 to 8 times, preferably 1.2 times, of the monohydroxybenzene monomer.

[0056] In one embodiment of the present invention, the feed amount of monohydroxybenzene monomer in each stage of the reaction device independently accounts for 10-50% of the total monohydroxybenzene monomer feed mass, preferably 100% / n, where n is the total number of reaction devices in series.

[0057] In one embodiment of the present invention, the molar ratio of the monohydroxybenzene monomer to the dihydroxybenzene monomer is 6 to 39:1, such as 6:1, 10:1, 15:1, 20:1, 25:1, 30:1, 35:1 or 39:1, but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable, preferably 23:1.

[0058] A specific embodiment of the present invention provides a system for preparing high hydroxyl value polyphenylene ether, the system comprising:

[0059] At least three stages of reaction devices are connected in series, and the raw material inlets of the reaction devices at each stage are independently connected to the monohydroxybenzene monomer feed pipeline; the first stage reaction device is provided with a dihydroxybenzene monomer feed inlet, and the dihydroxybenzene monomer feed inlet is connected to the dihydroxybenzene monomer feed pipeline; the oxidizing gas inlets of the reaction devices at each stage are independently connected to the oxidizing gas feed pipeline;

[0060] Each stage of the reaction device is independently provided with an external circulation pipeline, and the external circulation pipeline of each stage of the reaction device is provided with a discharge port, which is independently connected to the raw material inlet of the next stage of the reaction device. The discharge port of the circulation pipeline of the last stage of the reaction device is connected to the feed port of the redistribution reaction device, and the feed port of the redistribution reaction device is connected to the redistribution monomer feed pipeline.

[0061] In the present invention, the reaction is completed using a series of tank reactors. Compared to the traditional production process using a single tank reactor, continuous production is achieved. The high molecular weight polyphenylene ether is continuously removed during the reaction, resulting in a smaller molecular weight distribution of the product polyphenylene ether. At the same time, by limiting the content of polymerized monomers in a single tank, the reaction between polymerized monomers to form monohydroxy polyphenylene ether molecular chains is reduced, thereby increasing the hydroxyl functionality of the product.

[0062] In a specific embodiment of the present invention, the number of series-connected reaction devices can be 3, 4 or 5, etc., but is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0063] In a specific embodiment of the present invention, a stirring assembly is provided inside each stage of the reaction device to stir the reaction materials and improve the mass transfer and heat transfer efficiency of the reactants.

[0064] In one embodiment of the present invention, the system for preparing high-hydroxyl-value polyphenylene ether further comprises a dihydroxybenzene monomer storage device, a monohydroxybenzene monomer storage device, and a solvent storage device. The dihydroxybenzene monomer storage device is connected to the first-stage reaction device via a dihydroxybenzene monomer feed line, the monohydroxybenzene monomer storage device is connected to each stage of the reaction device via a monohydroxybenzene monomer feed line, and the solvent storage device is connected to each stage of the reaction device via a solvent feed line. The solvent storage device can be connected to the dihydroxybenzene monomer feed line or the monohydroxybenzene monomer feed line via a pipeline, and the solvents are mixed in the pipeline before entering the storage devices at each stage.

[0065] In a specific embodiment of the present invention, the system for preparing high hydroxyl value polyphenylene ether further includes an oxidizing gas storage device connected to the redistribution reaction device via an oxidizing gas feed pipeline.

[0066] In one embodiment of the present invention, the external circulation pipelines of each stage of the reaction apparatus are independently provided with heat exchange devices, which are used to heat the external circulation materials to heat the materials inside the reactor.

[0067] In a specific embodiment of the present invention, the external circulation pipelines of each stage of the reaction device are independently provided with external circulation material conveying devices, such as external circulation pumps.

[0068] In one embodiment of the present invention, the system for preparing high hydroxyl value polyphenylene ether further comprises a redistribution monomer storage device connected to the redistribution reaction device via a redistribution monomer feed pipeline.

[0069] In a specific embodiment of the present invention, the redistribution reaction device is provided with a discharge port, which is connected to the post-processing section.

[0070] In one embodiment of the present invention, the post-processing section includes a copper removal device, a product separation device, a washing device, a drying device, etc., for obtaining a pure polyphenylene ether product.

[0071] In a specific embodiment of the present invention, the specific sizes and models of the reaction device, redistribution reaction device, dihydroxybenzene monomer storage device, monohydroxybenzene monomer storage device, solvent storage device, redistribution monomer storage device, oxidizing gas storage device and heat exchange device included in the preparation system of high hydroxyl value polyphenylene ether can be adjusted according to the production scale and production needs, and are not further limited here.

[0072] In one specific embodiment of the present invention, during the process of withdrawing part of the material from the discharge port of the external circulation pipeline to the next-stage reaction device for continuous reaction and withdrawing part of the material from the discharge port of the external circulation pipeline of the last-stage reaction device to the redistribution reaction device, corresponding monohydroxybenzene monomer, dihydroxybenzene monomer and solvent are added to the reaction devices at each stage to maintain the liquid level in the reaction device stable.

[0073] In one embodiment of the present invention, based on the molar amount of monomers added in the same time, the ratio of the feeding rate of the monohydroxybenzene monomer to the bis(benzene)hydroxy monomer is 6 to 39:1, preferably 23:1.

[0074] In one embodiment of the present invention, the reaction temperature of each stage of the reaction apparatus is maintained by a heating device in the external circulation pipeline. The reaction temperature is 30°C to 70°C, such as 30°C, 40°C, 50°C, 60°C, or 70°C, but is not limited to the values ​​listed above. Other values ​​not listed in this numerical range are also applicable. The pressure of each stage of the reaction is 0.8 to 1.25 bar, preferably 1 bar.

[0075] In one specific embodiment of the present invention, the reaction time of each stage of the reaction device, that is, the residence time of the material in each stage of the reaction device is 40 to 90 min, such as 40 min, 50 min, 60 min, 70 min, 80 min or 90 min, etc., but is not limited to the enumerated values. Other values ​​not listed within the numerical range are also applicable, preferably 69.4 min.

[0076] In one embodiment of the present invention, the redistribution monomer includes a dihydroxy compound, and the dihydroxy compound includes 3,3,5,5-tetramethyl-4,4-biphenyldiphenol.

[0077] In one embodiment of the present invention, the molar ratio of the redistribution monomer to the dihydroxybenzene monomer is 0.1 to 4:1, such as 0.1:1, 0.2:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1 or 4:1, etc., and is not limited to the listed values. Other values ​​not listed within the numerical range are also applicable.

[0078] In the present invention, the product polyphenylene ether undergoes a redistribution reaction with a bisphenol in an aging kettle, further increasing the proportion of dihydroxy molecules in the product while reducing the product's molecular weight distribution. The addition of a redistribution monomer during the redistribution reaction can reduce the molecular weight of the product polyphenylene ether. By varying the amount of the redistribution monomer added, the product specifications can be further adjusted. In particular, when preparing polyphenylene ether with a molecular weight of less than 1000, the redistribution reaction converts high-molecular-weight polyphenylene ether into a low-molecular-weight product, effectively avoiding the problem of a large amount of oligomers in the product when preparing low-molecular-weight polyphenylene ether using conventional synthesis methods.

[0079] In one embodiment of the present invention, the polyphenylene ether prepared by the above-described method for preparing a high-hydroxyl polyphenylene ether has a number average molecular weight of 500 to 5000 atomic mass units, with a molecular weight distribution ranging from 1.8 to 2.3. Although the average molecular weight is controlled within a certain range, very low levels of low-molecular-weight polymers and residual monomers are still present in the polymer. The hydroxyl value of the substance is measured by titration, and the average hydroxyl functionality is calculated. The hydroxyl functionality of the product is between 1.9 and 2.0, and the proportion of dihydroxy polyphenylene ether molecules is greater than 97%.

[0080] To better illustrate the present invention and facilitate understanding of the technical solutions of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0081] Example 1

[0082] This embodiment provides a system for preparing high hydroxyl value polyphenylene ether, the structure of which is as follows: Figure 1 As shown, the preparation system includes:

[0083] Three stages of reactors connected in series, namely reactor 1, reactor 2 and reactor 3 connected in sequence, the raw material inlets of reactor 1, reactor 2 and reactor 3 are independently connected to the monohydroxybenzene monomer feed pipeline; reactor 1 is provided with a dihydroxybenzene monomer feed inlet, and the dihydroxybenzene monomer feed inlet is connected to the dihydroxybenzene monomer feed pipeline; the oxidizing gas inlets of reactor 1, reactor 2 and reactor 3 are independently connected to the oxidizing gas feed pipeline;

[0084] Reactor 1, reactor 2 and reactor 3 are respectively independently provided with external circulation pipelines, and the external circulation pipelines of reactor 1, reactor 2 and reactor 3 are provided with discharge ports. The discharge ports of the external circulation pipelines of reactor 1 and reactor 2 are respectively and independently connected to the raw material inlet of the next-stage reactor, and the discharge port of the circulation pipeline of reactor 3 is connected to the feed port of the redistribution reactor. The external circulation pipelines of reactor 1, reactor 2 and reactor 3 are all provided with heat exchangers and circulation pumps; reactor 1, reactor 2 and reactor 3 are all provided with stirring components; the inner radius of a single reactor is 25 cm, the inner height of the reactor is 80 cm, and the reactor capacity is 150 L; the inner radius of the conduit connecting the two reactors is 1.5 cm.

[0085] The feed port of the redistribution reactor is connected to the redistribution monomer feed pipeline, and the discharge port of the redistribution reactor is connected to the post-processing section.

[0086] Example 2

[0087] This embodiment provides a method for preparing high-hydroxyl-value polyphenylene ether, which uses the preparation system for high-hydroxyl-value polyphenylene ether provided in Example 1. The preparation method includes:

[0088] 22.8 kg (127.4 mol) of tetramethylbisphenol F, 91.2 kg of toluene, 181.9 g (0.01 eq, 1.27 mol, 143.4 da) of catalyst cuprous bromide, 437.6 g (0.02 eq, 2.54 mol, 172.3 da) of ligand N,N'-di-tert-butylethylenediamine, and 129.9 g (0.005 eq, 0.64 mol, 202.2 da) of auxiliary agent DIAD were stirred and mixed to obtain a first material; 231.7 kg of xylenol (1.90 kmol) and 926.7 kg of solvent toluene were stirred and mixed to obtain a second material;

[0089] 85.6 kg of toluene was added to each of the three reactors. The external circulation of reactors 1, 2, and 3 was opened, and the materials in the reactors were pumped into the external circulation pipeline. The openings of the pipeline valves between reactors 1 and 2, between reactors 2 and 3, and between reactor 3 and the redistribution reactor were all 0. After the temperature of the materials in the reactors was controlled to 45°C through the heat exchanger on the circulation branch, the oxygen inlet was opened and oxygen was introduced into the three reactors at a rate of 4.94 kg / h.

[0090] The first material was added to reactor 1 at a rate of 22.8 kg / h, and the second material was added to each of the three reactors at a rate of 77.2 kg / h. Simultaneously, the three valves were opened to adjust the flow rate between reactor 1 and reactor 2 to 100.0 kg / h, the flow rate between reactor 2 and reactor 3 to 177.2 kg / h, and the flow rate between reactor 3 and the redistribution reactor to 254.5 kg / h. The redistribution reactor was maintained under stirring and kept at 45° C., while a 20% toluene solution of the redistribution monomer tetramethylhydroquinone was added to the reactor at a rate of 6.05 kg / h.

[0091] After the reaction was continued for 5 hours, the raw material was exhausted, and the residual material was drained and combined into the post-processing step; the material was washed with EDTA solution to remove the residual copper element, and then added to methanol to precipitate polyphenylene ether. The solid was filtered out and washed and dried to obtain 253.3 kg of polyphenylene ether with a yield of 97.2%.

[0092] The product was sampled and the intrinsic viscosity of the polymer was measured using an Ubbelohde viscometer according to the method in GBT1632-1993. The molecular weight and molecular weight distribution data of the polymer were calculated. The product molecular weight Mn=3045, the molecular weight distribution was 1.91, the hydroxyl value was 36.2 mgKOH / g, and the functionality was 1.97.

[0093] Example 3

[0094] This embodiment provides a method for preparing high-hydroxyl-value polyphenylene ether, which uses the preparation system for high-hydroxyl-value polyphenylene ether provided in Example 1. The preparation method includes:

[0095] 22.8 kg (127.4 mol) of tetramethylbisphenol F and 91.2 kg of toluene, 181.9 g (0.01 eq, 1.27 mol, 143.4 da) of copper bromide catalyst, 437.6 g (0.02 eq, 2.54 mol, 172.3 da) of ligand N,N'-di-tert-butylethylenediamine, and 129.9 g (0.005 eq, 0.64 mol, 202.2 da) of auxiliary agent DIAD were stirred and mixed to obtain a first material; 231.7 kg of xylenol (1.90 kmol) and 926.7 kg of toluene solvent were stirred and dissolved to obtain a second material;

[0096] 85.6 kg of toluene was added to each of the three reactors. The external circulation of reactors 1, 2, and 3 was opened, and the materials in the reactors were pumped into the external circulation pipeline. The openings of the pipeline valves between reactors 1 and 2, between reactors 2 and 3, and between reactor 3 and the redistribution reactor were all 0. After the temperature of the materials in the reactors was controlled to 45°C by the heat exchanger on the external circulation pipeline, the oxygen inlet was opened and oxygen was introduced into the three reactors at a rate of 4.94 kg / h.

[0097] The first material was added to Reactor 1 at a rate of 22.8 kg / h, and the second material was added to each of the three reactors at a rate of 77.2 kg / h. Simultaneously, the three valves were opened to ensure that the flow rate between Reactor 1 and Reactor 2 was 100.0 kg / h, the flow rate between Reactor 2 and Reactor 3 was 177.2 kg / h, and the flow rate between Reactor 3 and the redistribution reactor was 254.5 kg / h. The redistribution reactor was maintained under stirring and kept at 45°C. Simultaneously, a 50% toluene solution of the redistribution monomer tetramethylhydroquinone was added to the reactor at a rate of 38.7 kg / h.

[0098] After 5 hours of continuous reaction, the raw material was depleted. The residual material in each reactor was drained and combined into a redistribution reactor. The temperature was maintained for another 30 minutes, and then the material was pumped to the post-processing step. After washing with EDTA solution to remove residual copper, the material was added to methanol to precipitate polyphenylene ether. The solid was filtered, washed, and dried to obtain 338.6 kg of polyphenylene ether, with a yield of 96.4%.

[0099] The product was sampled and the intrinsic viscosity of the polymer was measured using an Ubbelohde viscometer according to the method in GBT1632-1993. The molecular weight and molecular weight distribution data of the polymer were calculated. The product molecular weight Mn=1072, the molecular weight distribution was 1.88, the hydroxyl value was 103.4 mgKOH / g, and the functionality was 1.98.

[0100] Example 4

[0101] This embodiment provides a method for preparing high-hydroxyl-value polyphenylene ether, which uses the preparation system for high-hydroxyl-value polyphenylene ether provided in Example 1. The preparation method includes:

[0102] 10.6 kg (46.5 mol) of tetramethyl bisphenol F and 42.4 kg of toluene were added with 77.4 g (0.01 eq, 0.54 mol, 143.4 da) of cuprous bromide catalyst, 186.1 g (0.02 eq, 1.08 mol, 172.3 da) of ligand N,N'-di-tert-butylethylenediamine and 54.6 g (0.005 eq, 0.27 mol, 202.2 da) of auxiliary agent DIAD, and stirred to obtain a first material; 243.9 kg of xylenol (2.00 kmol) and 975.5 kg of toluene solvent were stirred, dissolved and mixed to obtain a second material;

[0103] 85.6 kg of toluene was added to each of the three reactors, and the external circulation of reactor 1, reactor 2, and reactor 3 was opened, and the materials in the reactors were pumped into the external circulation pipeline; the openings of the pipeline valves between reactor 1 and reactor 2, between reactor 2 and reactor 2, and between reactor 3 and the storage tank were all 0; after the temperature of the materials in the reactors was controlled to 45°C through the heat exchanger on the external circulation pipeline, the oxygen inlet was opened, and oxygen was introduced into the three reactors at a rate of 5.09 kg / h;

[0104] The first material was added to reactor 1 at a rate of 10.6 kg / h, and the second material was added to each of the three reactors at a rate of 81.3 kg / h. Simultaneously, the three valves were opened to ensure that the flow rate between reactor 1 and reactor 2 was 91.9 kg / h, the flow rate between reactor 2 and reactor 3 was 173.2 kg / h, and the flow rate between reactor 3 and the storage tank was 254.5 kg / h. The redistribution reactor was maintained under stirring and kept at 45°C. Meanwhile, a 20% toluene solution of the redistribution monomer tetramethylhydroquinone was added to the reactor at a rate of 1.12 kg / h.

[0105] After the reaction was continued for 5 hours, the raw materials were exhausted, and the materials in each reactor were drained and combined into a storage tank. The materials in the storage tank were washed with EDTA solution to remove residual copper elements, and then added to methanol to precipitate polyphenylene ether. The solid was filtered out, washed and dried to obtain 250.8 kg of polyphenylene ether with a yield of 98.1%.

[0106] The product was sampled and the intrinsic viscosity of the polymer was measured using an Ubbelohde viscometer according to the method in GBT1632-1993. The molecular weight and molecular weight distribution data of the polymer were calculated. The product had a molecular weight Mn of 4973, a molecular weight distribution of 2.04, a hydroxyl value of 22.1 mg KOH / g, and a functionality of 1.96 mol / mol.

[0107] Example 5

[0108] The same protocol as in Example 2 was followed, except that the catalyst dosage was changed to 0.03 mol per mol of dihydroxybenzene monomer. Furthermore, the material addition rate was increased to 1.39 times that of Example 1, with the first material added to Reactor 1 at a rate of 40.4 kg / h, and the second material added to each of the three reactors at a rate of 104.4 kg / h. After the reaction began, the three valves were opened to achieve a flow rate of 144.8 kg / h between Reactor 1 and Reactor 2, a flow rate of 249.3 kg / h between Reactor 2 and Reactor 2, and a flow rate of 353.7 kg / h between Reactor 3 and the storage tank, ensuring an average residence time of 50 min within the apparatus.

[0109] Example 6

[0110] The same protocol as in Example 2 was followed, except that the catalyst dosage was changed to 0.001 mol per mol of dihydroxybenzene monomer. Furthermore, the material addition rate was increased to 0.69 times that of Example 1, i.e., the first material was added to Reactor 1 at a rate of 20.2 g / h, and the second material was added to each of the three reactors at a rate of 72.3 kg / h. After the reaction began, the three valves were opened to ensure a flow rate of 72.3 kg / h between Reactor 1 and Reactor 2, 124.5 kg / h between Reactor 2 and Reactor 2, and 176.6 kg / h between Reactor 3 and the storage tank, ensuring an average residence time of 100 min.

[0111] Examples 7-9

[0112] Polyphenylene ether was prepared according to the same protocol as in Example 2, except that the heat exchanger temperature control standard was changed so that the material temperatures during the reaction were maintained at 40°C, 50°C, and 55°C, respectively. The material ratios and other reaction conditions were the same as in Example 2. Samples of the prepared polyphenylene ether products were collected, and the molecular weight, molecular weight distribution, hydroxyl value, and other data of the three batches of products were measured.

[0113] Examples 10-12

[0114] Following the same protocol as in Example 2, during the preparatory stage, the amounts of solvent used to dilute the dihydroxybenzene monomer and the monohydroxybenzene monomer were changed to 3 times, 2 times, and 5 times the monomer mass, respectively. The material ratios and other reaction conditions remained the same as in Example 2. Samples of the prepared polyphenylene ether product were collected and tested for molecular weight, molecular weight distribution, hydroxyl value, and other data for the three batches.

[0115] Examples 13-14

[0116] Following the same protocol as in Example 2, the amounts of ligand added during the preparation of the first material were changed to 5 eq and 0.3 eq of copper salt, respectively. The raw material ratios and other reaction conditions were the same as in Example 2. Samples of the resulting polyphenylene ether product were collected and tested for molecular weight, molecular weight distribution, hydroxyl number, and other data.

[0117] Examples 15-16

[0118] Following the same protocol as in Example 2, DEAD and DBAD were used in place of DIAD in the preparatory stage, respectively, with the molar amounts of the additives remaining unchanged. The raw material ratios and other reaction conditions were the same as in Example 2. The resulting polyphenylene ether products were sampled and tested for molecular weight, molecular weight distribution, hydroxyl value, and other data.

[0119] The reaction conditions of Examples 2-16 are shown in Table 1.

[0120] Table 1

[0121]

[0122] Comparative Example 1, single-pot reaction

[0123] A 150L single-bottle reactor was charged with 2.9kg (12.7mol) of tetramethylbisphenol F and 11.6kg of toluene. The catalyst, cuprous bromide (18.2g (0.01eq, 0.127mol, 143.4da), the ligand, N,N'-di-tert-butylethylenediamine (43.8g (0.02eq, 0.25mol, 172.3da), and the additive, DIAD (13.0g (0.005eq, 0.042mol, 202.2da), were added and stirred until thoroughly mixed. In another mixing vessel, 22.5kg (185mol) of xylenol and 90.2kg of toluene were added and stirred until thoroughly dissolved.

[0124] After heating the reactor to 45°C, oxygen was introduced into the reactor at a rate of 2.96 kg / h. After maintaining oxygen flow for 10 minutes, the materials in the mixing kettle were uniformly added to the reactor at a rate of 1.96 kg / min. After 1 hour, the raw monomers were added. The reaction was maintained at this temperature for 30 minutes. An EDTA solution was then added to the storage tank to remove residual copper. The organic phase was separated and added to methanol to precipitate the polyphenylene ether. The solid was filtered, washed, and dried. Samples were taken to test the molecular weight and hydroxyl value of the product.

[0125] Comparative Example 2: All monomers were added to the first reactor without batching.

[0126] The same protocol as in Example 2 was followed, except that when the raw materials were added to the reactor, the first material was added to Reactor 1 at a rate of 29.1 kg / h, and the second material was added to Reactor 1 at a rate of 225.4 kg / h. The flow rates between Reactor 1 and Reactor 2, between Reactor 2 and Reactor 2, and between Reactor 3 and the storage tank were all set to 254.5 kg / h. After the reaction was continued for 5 hours, the raw materials were exhausted, and redistribution reaction and post-processing were carried out in the same manner as in Example 2 to obtain a solid polyphenylene ether product. The product was sampled and tested for molecular weight and hydroxyl value.

[0127] Comparative Example 3: No catalyst additive was added

[0128] According to the same scheme as Example 2, when preparing the first material, no azodicarboxylate catalyst auxiliary was added. Other parameters and operating standards were kept consistent with Example 2 to prepare polyphenylene ether solid, and the molecular weight and hydroxyl value data of the product were tested by sampling.

[0129] Comparative Example 4: No redistribution reaction

[0130] According to the same scheme as Example 2, except that the amount of redistribution monomer added to the redistribution reactor was 0, that is, no redistribution monomer was added, but the heat preservation and redistribution reaction process was still maintained for 5 hours. Apart from this, other parameters and operating standards were kept consistent with Example 2 to prepare polyphenylene ether solid, and the molecular weight and hydroxyl value data of the product were sampled and tested.

[0131] The product data of Examples 2-16 and Comparative Examples 1-4 are shown in Table 2.

[0132] Table 2

[0133]

[0134] The test results in Table 2 indicate that the polyphenylene ether prepared by the system and method for preparing high-hydroxyl-value polyphenylene ether provided by the present invention exhibits uniform molecular weight distribution, high hydroxyl value, and a high proportion of dihydroxy polyphenylene ether molecules. Examples 7-9 indicate that increasing the reaction temperature improves the yield of the polyphenylene ether product, but increases the molecular weight and decreases the hydroxyl value. Examples 10-12 indicate that the effect of solvent amount on the yield, molecular weight, and hydroxyl value of the polyphenylene ether product is not uniform. Examples 13 and 14 indicate that increasing the amount of copper-based catalyst, i.e., the main catalyst, improves the yield of the polyphenylene ether product, but decreases the hydroxyl value of the polyphenylene ether. Examples 15 and 16 indicate that while DEAD produces the highest hydroxyl value of the polyphenylene ether product, the yield is lower. While DBAD produces a higher yield of the polyphenylene ether product, the hydroxyl value is lower, resulting in DIAD offering the best overall performance.

[0135] Comparative Examples 1 and 2 demonstrate that the monomer material access method affects the reaction selectivity. By controlling the content of polymer monomers in the system, the proportion of monomers self-polymerizing to form monohydroxy polymers can be significantly reduced. In Comparative Example 1, a single-pot reaction is used, which cannot be produced continuously. Although the polyphenylene ether yield is high, the hydroxyl value of the polyphenylene ether is only 40.8 mgKOH / g. This indicates that in the single-pot reaction, the product cannot be removed from the reaction system, resulting in excessive polymerization of the monohydroxybenzene monomer, which reduces the content of dihydroxy polyphenylene ether in the product and the hydroxyl value of the product. In Comparative Example 2, although a series of reactors are used for the reaction, the raw materials are added to reactor 1 at one time, resulting in an excessively high content of monohydroxybenzene monomer in reactor 1. The monohydroxybenzene monomer is excessively polymerized in reactor 1, which reduces the content of dihydroxy polyphenylene ether in the product and the hydroxyl value of the product, which is only 47.4 mgKOH / g. In addition, the activity of the catalyst also affects the hydroxyl value of the reaction product. In Comparative Example 3, no catalyst adjuvant was used. Since the reaction could not consume the added polymerization monomer in time, the monomers were mutually oxidized and polymerized into monohydroxy polymers. The hydroxyl content of the product was low, and the yield of polyphenylene ether decreased significantly, only 91.9%. This is because the monomers and some oligomers that failed to react during the reaction process could not be well precipitated in the material post-processing step and were lost in the solution. Comparative Example 4, Example 2, and Example 3 demonstrate the role of the redistribution reagent in the redistribution step in adjusting the product molecular weight, reducing the product molecular weight distribution, and adjusting the hydroxyl value of the polyphenylene ether product. In Comparative Example 4, the redistribution monomer was completely removed, and the hydroxyl content of the product could not be increased by integrating the dihydroxy redistribution monomer into the monohydroxy molecule. At the same time, the product molecular weight distribution was also high. This is because the redistribution reaction activity between polymer chains is low during the constant temperature redistribution reaction without the addition of the redistribution monomer, and the redistribution reaction effect is poor.

[0136] The applicant declares that the present invention is intended to illustrate the detailed structural features of the present invention through the above-described embodiments, but the present invention is not limited to the above-described detailed structural features. This does not mean that the present invention must rely on the above-described detailed structural features in order to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for selected components, additions of auxiliary components, and selection of specific embodiments, etc., fall within the scope of protection and disclosure of the present invention.

[0137] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0138] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0139] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing high hydroxyl value polyphenylene ether, characterized in that: The preparation method comprises: After mixing a dihydroxybenzene monomer, a monohydroxybenzene monomer, a catalyst and a solvent, an oxidizing gas is introduced to carry out a first stage polymerization reaction to obtain a first stage polymerization product; The first stage polymerization product is mixed with a monohydroxybenzene monomer, a catalyst and a solvent, and then an oxidizing gas is introduced to carry out a second stage polymerization reaction to obtain a second stage polymerization product; The polymerization reaction is carried out at least three times; The final polymerization product is mixed with a redistribution monomer to undergo a redistribution reaction to obtain the polymerization product; The dihydroxybenzene monomer includes tetramethyl bisphenol F and / or tetramethyl bisphenol A, and the monohydroxybenzene monomer includes 2,6-dimethylphenol; The catalyst includes a main catalyst and a catalyst promoter; the main catalyst is a combination of a metal salt and a ligand, the metal salt includes any one of cuprous chloride, cuprous bromide, cupric chloride or cupric bromide or a combination of at least two thereof; the ligand includes any one of dimethylamine, diethylamine, trimethylamine, triethylamine, tripropylamine, tributylamine, diethylmethylamine, dimethylpropylamine, N,N-dimethyl-n-butylamine, N,N-di-tert-butylethylenediamine or N,N-diisopropylethylenediamine or a combination of at least two thereof; the catalyst promoter includes azodicarboxylic acid ester; the azodicarboxylic acid ester includes any one of diethyl azodicarboxylate, diisopropyl azodicarboxylate or tert-butyl azodicarboxylate or a combination of at least two thereof; The preparation system used in the preparation method includes at least three stages of reaction devices connected in series, and the raw material inlets of the reaction devices at each stage are independently connected to the monohydroxybenzene monomer feed pipeline; the first stage of the reaction device is provided with a dihydroxybenzene monomer feed inlet, and the dihydroxybenzene monomer feed inlet is connected to the dihydroxybenzene monomer feed pipeline; the oxidizing gas inlets of the reaction devices at each stage are independently connected to the oxidizing gas feed pipeline.

2. The preparation method according to claim 1, characterized in that The molar ratio of the monohydroxybenzene monomer to the dihydroxybenzene monomer is 6 to 39:

1.

3. The preparation method according to claim 1, characterized in that The reaction temperature of each stage of the reaction device is maintained by a heating device of the external circulation pipeline, and the reaction temperature is 30~70℃; The reaction time of each stage of the reaction device is 40 to 90 minutes.

4. The preparation method according to claim 1, characterized in that The redistribution monomer includes a dihydroxy compound; The dihydroxy compound includes 3,3,5,5-tetramethyl-4,4-biphenyldiphenol.

5. The preparation method according to claim 1, characterized in that The molar ratio of the redistribution monomer to the dihydroxybenzene monomer is 0.1 to 4:

1.

6. The preparation method according to claim 1, characterized in that The reaction devices at each stage are independently provided with external circulation pipelines, and the external circulation pipelines of the reaction devices at each stage are provided with discharge ports, which are independently connected to the raw material inlet of the next stage reaction device. The discharge port of the circulation pipeline of the last stage reaction device is connected to the feed port of the redistribution reaction device, and the feed port of the redistribution reaction device is connected to the redistribution monomer feed pipeline.

7. The preparation method according to claim 6, characterized in that The external circulation pipelines of the reaction devices at each stage are independently provided with heat exchange devices.

8. The preparation method according to claim 6, characterized in that The redistribution reaction device is provided with a discharge port, and the discharge port is connected to the post-processing section.

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