Polyphenylene ether resin and preparation method thereof

Abstract

The present application provides a method for preparing a polyphenylene ether resin, characterized in that, in the presence of a solvent and a coordinated metal catalyst, an oxygen-containing gas is introduced into a circulation pipeline provided outside a polymerization reactor to produce a reaction mixture of a polyphenylene ether resin by oxidative coupling of a monohydric phenol, wherein a static mixer having a gas introduction portion is provided in the circulation pipeline. By achieving a low TMDPQ (TetraMethylDiPhenoQuinone) production amount that cannot be achieved by the existing PPE (Polyphenyl Ether) preparation method, the design freedom of PPE is expanded, and the economic efficiency is improved by increasing the polymerization speed and shortening the polymerization time.

Description

Technical Field

[0001] The invention relates to a method for preparing polyphenylene ether and the polyphenylene ether prepared by the method. Background Art

[0002] Polyphenylene ether (hereinafter referred to as PPE) resin is widely known and widely used as a thermoplastic having properties such as heat resistance, rigidity, and high impact strength. In addition, in order to cope with the use of electronic substrates of electronic devices of 5G (fifth generation communication technology), there is a growing demand for the development of thermosetting resins using low molecular weight PPE as a raw material.

[0003] Various processes are known for preparing PPE homopolymers and copolymers, for example, involving the self-condensation of a polyhydric phenol in the presence of an oxygen-containing gas and a catalyst.

[0004] However, the molecular structure of 2,6-dimethylphenol in PPE after polymerization by the above method is a linear polymer, and only one side of the molecular structure has a phenolic OH group. In addition, as PPE is generated, a byproduct 3,3',5,5'-tetramethyl-4,4'-diphenylquinone (hereinafter referred to as TMDPQ) is generated. Since this TMDPQ will cause the deterioration of the color of the PPE resin product, it should be removed as much as possible. This TMDPQ as a byproduct can be removed by adding a reducing agent and dissolving it in an organic solvent, or by bonding to the PPE molecular chain through a redistribution reaction with PPE.

[0005] If it is bonded to the PPE molecular chain through a redistribution reaction with PPE, a structure with OH groups on both sides of the PPE molecular ends will be formed depending on the amount of TMDPQ bonded. Theoretically, if one TMDPQ is introduced into each molecule, OH groups will exist on both ends of all molecules.

[0006] Generally speaking, when TMDPQ is bonded to the PPE molecular chain by redistribution, the molecular weight distribution (PDI, Polymer Dispersion Index) is expanded, and it is expected that the melt fluidity of the resin composition after being formed is improved, but there is a possibility that the impact resistance is reduced.

[0007] Therefore, as a means to reduce the amount of TMDPQ generated, there is a means to increase the oxygen supply relative to the monomer amount as much as possible. However, if the oxygen supply is too much, unreacted oxygen will be released from the polymerization solution, and an explosive mixed gas with the organic solvent will be generated, resulting in fire and explosion. Therefore, in order to prevent unreacted oxygen from being released from the polymerization solution, the oxygen supply rate has to be suppressed. In addition, if the oxygen supply is suppressed, it may also become an obstacle to shortening the polymerization time.

[0008] In addition, in the polymerization method of PPE in the prior art, oxygen or oxygen-containing gas is introduced into the polymerization kettle through a nozzle or the like and dispersed into a fine state, and in this state, the oxidation reaction is carried out by contacting with the polymerization solution. The finer the opening of the nozzle or the like for supplying oxygen or oxygen-containing gas, the finer the gas supply will be, but if it is too fine, the opening is prone to the attachment of TMDPQ crystals, thereby causing occlusion of the opening. On the contrary, if the supply of oxygen or oxygen-containing gas is not sufficiently fine, the contact area between oxygen and the polymerization solution is reduced, so the reaction efficiency is reduced, and unreacted oxygen may escape to the gas phase of the polymerization kettle. Summary of the invention

[0009] In order to solve at least one of the above-mentioned technical problems, the object of the present invention is to provide a method for preparing polyphenylene ether, which can expand the design freedom of PPE by achieving a low TMDPQ production amount that cannot be achieved by the existing PPE preparation method, and improve the economic efficiency by increasing the polymerization rate and shortening the polymerization time.

[0010] Specifically, the first aspect of the present invention provides a method for preparing a polyphenylene ether resin, characterized in that, in the presence of a solvent and a coordinated metal catalyst, an oxygen-containing gas is introduced into a circulation pipeline arranged outside a polymerization reactor to cause oxidative coupling of monohydric phenol to produce a reaction mixture of a polyphenylene ether resin, wherein a static mixer with a gas introduction portion is arranged in the circulation pipeline.

[0011] In the method for preparing the polyphenylene ether resin of the present invention, the oxygen-containing gas is oxygen or a mixture of oxygen and other gases, preferably oxygen.

[0012] In the method for preparing the polyphenylene ether resin of the present invention, the flow rate of the oxygen-containing gas in the gas introduction section is set to 0.5 to 2.5 NL / min, preferably 1.0 to 1.9 NL / min, based on the amount of oxygen introduced per kilogram of the monohydric phenol.

[0013] In the method for preparing the polyphenylene ether resin of the present invention, the linear velocity of the solution passing through the mixer in the circulation pipeline is 1.0 to 10.0 m / s, preferably 1.5 to 8.0 m / s, and more preferably 2.0 to 6.0 m / s.

[0014] In the method for preparing the polyphenylene ether resin of the present invention, the internal pressure downstream of the static mixer is 0.01 to 0.5 MPa, preferably 0.05 to 0.3 MPa.

[0015] In the method for preparing the polyphenylene ether resin of the present invention, nitrogen is introduced into the polymerization vessel from a nitrogen inlet provided at the top of the polymerization vessel to nitrogen-seal the reaction solution.

[0016] In the method for preparing the polyphenylene ether resin of the present invention, the circulation pipeline is further provided with one or more of an online viscometer, a shell-and-tube heat exchanger, a thermometer, and a pressure gauge.

[0017] A second aspect of the present invention provides a polyphenylene ether resin, characterized in that it is prepared according to the above-mentioned preparation method, wherein the content of TMDPQ is less than 0.3% by mass, preferably less than 0.1% by mass, and more preferably less than 0.05% by mass relative to the total mass of the polyphenylene ether resin polymerization solution.

[0018] In the polyphenylene ether resin involved in the present invention, the intrinsic viscosity of the polyphenylene ether resin is 0.05 to 2.0 dL / g; at 25°C and in chloroform solvent, the intrinsic viscosity of the polyphenylene ether resin is greater than 0.1 dL / g, preferably greater than 0.2 dL / g, more preferably greater than 0.25 dL / g, and particularly preferably greater than 0.30 dL / g; the intrinsic viscosity of the polyphenylene ether resin is less than 1.6 dL / g, preferably less than 1.0 dL / g, more preferably less than 0.5 dL / g, and particularly preferably less than 0.45 dL / g.

[0019] In the polyphenylene ether resin involved in the present invention, the polyphenylene ether resin has an intrinsic viscosity measured in chloroform at 25°C of 0.05 to 0.15 dL / g when used as a raw material for a thermosetting resin and 0.3 to 0.75 dL / g when used as a raw material for a thermoplastic resin.

[0020] Effects of the Invention

[0021] According to the preparation method of the polyphenylene ether resin involved in the present invention, a polyphenylene ether resin product with low TMDPQ generation can be obtained, the design freedom of PPE is expanded, and the economic efficiency is improved by controlling various reaction conditions in the reaction, thereby increasing the polymerization rate and shortening the polymerization time. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is an overall schematic diagram of the polymerization device involved in the present invention.

[0023] Figure 2 It is a schematic diagram of the structure of a static mixer used in the polymerization device involved in the present invention.

[0024] Description of reference numerals:

[0025] 1. Polymerization kettle; 2. Online viscometer; 3. Reaction circulation pump; 4. Circulation cooler; 5. Static mixer; 6. Tail gas condenser; 7. Gas-liquid separation tank; 51. Mixer body; 52. Gas inlet channel; 53. Bending plate; 54. Gas inlet port; M. Motor; A. Upstream of static mixer; B. Downstream of static mixer. DETAILED DESCRIPTION

[0026] Hereinafter, some embodiments of the polyphenylene ether resin prepared by the method of the present invention will be described.

[0027] A method for producing a polyphenylene ether according to one embodiment of the present invention is characterized in that a reaction mixture containing a polyphenylene ether resin is produced by oxidative coupling of a monohydric phenol using oxygen or an oxygen-containing gas in the presence of a solvent and a coordinated metal catalyst.

[0028] In one embodiment of the present invention, a gas-liquid mixing device is used in the polymerization apparatus in order to finely atomize the oxygen-containing gas to a level higher than that in the conventional art and to bring it into contact with the polymerization solution.

[0029] The specific gas-liquid mixing device is preferably disposed in the circulation pipeline of the polymerization kettle. The circulation pipeline transports the polymerization solution from the lower part of the polymerization kettle through a circulation pump and then returns it to the polymerization kettle. In addition to the specific gas-liquid mixing device of the present invention, the circulation pipeline may also be equipped with an online viscometer, a shell-and-tube heat exchanger for controlling the polymerization temperature, a thermometer, a pressure gauge, etc.

[0030] Generally speaking, the gas-liquid mixing device of the present invention is a static mixer called a static mixer. The static mixer is composed of a shape having a plurality of components that change the flow direction of the fluid inside the tube shape without using power.

[0031] As the static mixer used in the present invention, any shape, number and size of components may be used as long as it can supply oxygen-containing gas at a higher concentration compared with the method of reacting the polymerization solution by supplying oxygen-containing gas through a conventional nozzle or the like.

[0032] like Figure 1 As shown, the polymerization device involved in the present invention includes a polymerization kettle 1 and an external circulation pipeline. Raw materials such as monophenol and catalyst enter the polymerization kettle 1 through a raw material inlet arranged at the upper part of the polymerization kettle 1, and a nitrogen inlet for introducing nitrogen is also arranged at the upper part of the polymerization kettle 1.

[0033] The bottom of the polymerization kettle 1 is connected to an external circulation pipeline. During the reaction, the reaction liquid enters the external circulation pipeline from the bottom of the polymerization kettle 1. The reaction liquid entering the circulation pipeline is first tested for viscosity by an online viscometer 2, and then introduced into a circulation cooler 4 by a reaction circulation pump 3 for temperature reduction and cooling; then, the cooled reaction liquid is introduced into a static mixer 5 to mix with the oxygen-containing gas; then, the reaction liquid mixed with the oxygen-containing gas is transported back to the polymerization kettle 1 through the external circulation pipeline.

[0034] In addition, a gas phase circulation pipeline is also arranged at the upper part of the polymerization kettle 1. The gas in the gas phase part of the polymerization kettle 1 can reach the tail gas condenser 6 for condensation through the gas phase circulation pipeline. The condensed material passes through the gas-liquid separation tank 7 for gas-liquid separation, and the excess gas phase is discharged through the gas outlet arranged at the upper part of the gas-liquid separation tank 7.

[0035] like Figure 2 As shown, the reaction liquid is introduced into the mixer body 51 from the upstream of the static mixer 5. A gas introduction channel 52 is provided at the front end portion of the mixer body 51. The oxygen-containing gas is introduced into the mixer body 51 through the gas introduction port 54 via the gas introduction channel 52 and contacts with the reaction liquid. A plurality of deflection plates 53 are provided inside the mixer body 51. The reaction liquid forms turbulence between the plurality of deflection plates 53 in the mixer body 51, so that it can be fully mixed and reacted with the oxygen-containing gas.

[0036] The monohydric phenol used for the synthesis of polyphenylene ether is not particularly limited. Suitable monohydric phenols can be represented by the following formula.

[0037] Chemical formula 1:

[0038]

[0039] In the above formula, P 1 are independently halogen, C1-C7 primary or secondary alkyl, phenyl, C1-C7 haloalkyl, C1-C7 aminoalkyl, C1-C7 alkoxy, C2-C7 haloalkoxy having at least two carbon atoms separating the halogen atom and the oxygen atom, etc.; P 2 Each P is independently hydrogen, halogen, C1-C7 primary or secondary alkyl, phenyl, C1-C7 haloalkyl, C1-C7 alkoxy, C2-C7 halogenated alkoxy having at least two carbon atoms separating the halogen atom and the oxygen atom. 1 Preferably, it is an alkyl group or a phenyl group, and particularly preferably a C1-C4 alkyl group; each P 2 Preferred are hydrogen or methyl.

[0040] In a preferred embodiment, the monohydric phenol includes 2,6-dimethylphenol (hereinafter "DMP") and 2,3,6-trimethylphenol (hereinafter "TMP"). In this embodiment, any ratio of DMP and TMP from 99:1 to 1:99 by weight may be used. Within this range, it may be preferred to use a DMP:TMP weight ratio of at least about 1:1, more preferably at least about 3:1, and even more preferably at least about 4:1. Also within this range, it may be preferred to use up to about 20:1, more preferably up to about 10:1, and even more preferably up to about 6:1.

[0041] The oxygen-containing gas used in the present application can be oxygen or a mixed gas of oxygen and other gases, wherein the oxygen content of the mixed gas should not be less than 20% (v / v). The oxygen-containing gas is typically oxygen (O2) or air, wherein oxygen is preferred.

[0042] The monohydric phenol is oxidatively coupled in the presence of a solvent and a coordinated metal catalyst. Suitable organic solvents used in the preparation of polyphenylene ether resins in the present application include fatty alcohols, ketones, aliphatic and aromatic hydrocarbons, chlorinated hydrocarbons, nitro hydrocarbons, ethers, esters, amides, mixed ether-esters, sulfones, and combinations containing at least one of the foregoing organic solvents, provided that they do not interfere with or enter the oxidation reaction. In a preferred embodiment, the solvent includes C6-C 18 Aromatic hydrocarbons include, for example, toluene, xylene, etc. and mixtures thereof. The most preferred solvent is toluene.

[0043] Solvents other than C6-C 18 In addition to the aromatic hydrocarbons, the solvent may further include C3-C8 fatty alcohols (which are poor solvents for poly(arylene ether)), such as n-propanol, isopropanol, n-butanol, tert-butanol, n-pentanol, and the like, and combinations comprising at least one of the foregoing C3-C8 fatty alcohols. The preferred C3-C8 fatty alcohol is n-butanol. The solvent may further include methanol or ethanol, in addition to the C6-C18 aromatic hydrocarbons and the C3-C8 fatty alcohols, which act as anti-solvents for the poly(arylene ether). The C6-C 18 The aromatic hydrocarbons, C3-C8 fatty alcohols and methanol or ethanol may be used in any combination, but it is preferred that the solvent comprises at least about 50% by weight of C6-C8 fatty alcohols. 18 Aromatic hydrocarbons.

[0044] The coordinated metal catalyst may include metal ions. Preferred metal ions include ions of Groups VIB, VIIB or IB of the periodic table and combinations thereof. Among them, ions of chromium, manganese, cobalt, copper and combinations comprising at least one of the foregoing ions are preferred, with copper ions (Cu 2+) being the most preferred. + Cu 2+ ).

[0045] The coordinated metal catalyst may also include a nitrogen-containing ligand. The nitrogen-containing ligand may include, for example, an alkylenediamine ligand, a primary monoamine, a secondary monoamine, a tertiary monoamine, an amino alcohol, an oxime, a combination comprising at least one of the foregoing nitrogen-containing ligands, and the like.

[0046] Suitable alkylenediamine ligands include those having the formula:

[0047] (R b )2N-R a -N(R b )2

[0048] Among them, R ais a substituted or unsubstituted divalent residue in which two or three aliphatic carbon atoms form the tightest bond between the two diamine nitrogen atoms, and each R b are independently hydrogen or C1-C8 alkyl. Preferred alkylenediamine ligands include those wherein R a Those which are ethylene (-CH2CH2-) or trimethylene (-CH2CH2CH2-), and R b are independently hydrogen, isopropyl, or C4-C8 α-α-tertiary alkyl. Specific alkylenediamine ligands include N,N′-di-tert-butylethylenediamine and N,N,N′,N′-tetramethyl-1,3-diaminopropane.

[0049] Suitable primary monoamines include C3-C 12 Primary alkylamines, such as n-propylamine, isopropylamine, n-butylamine, sec-butylamine, tert-butylamine, n-pentylamine, n-hexylamine, cyclohexylamine, combinations comprising at least one of the foregoing primary monoamines, etc. The most preferred primary monoamine is n-butylamine.

[0050] Suitable secondary monoamines have 4 to 12 carbon atoms, for example, di-n-propylamine, n-propyl-n-butylamine, di-n-butylamine, di-tert-butylamine, n-butyl-n-pentylamine, di-n-hexylamine, etc., among which di-n-butylamine is preferred.

[0051] Suitable tertiary monoamines include those of the structure (R e )(R f )(R g )N tertiary monoamine, wherein R e , R f and R g Each independently is C1-C 16 Alkyl, provided that R e , R f and R g There are 4 to 18 carbon atoms in total. Examples of tertiary monoamines include triethylamine, tri-n-propylamine, tri-n-butylamine, dimethyl-n-butylamine, dimethyl-n-pentylamine, diethyl-n-butylamine, tricyclohexylamine, and the like. In addition, cyclic tertiary amines such as pyridine, α-collidine, γ-collidine, and the like may be used. Highly preferred tertiary monoamines include dimethyl-n-butylamine. Additional primary, secondary, and tertiary amines are disclosed in U.S. Pat. Nos. 3,306,874 and 3,306,875 to Hay.

[0052] Suitable amino alcohols include C4-C 12 Amino alcohols wherein at least two carbon atoms separate the amino nitrogen and the alcohol oxygen. Examples of amino alcohols include N,N-diethylethanolamine, 4-butanolamine, N-methyl-4-butanolamine, diethanolamine, triethanolamine, N-phenyl-ethanolamine, and the like, and combinations comprising at least one of the foregoing amino alcohols. Highly preferred amino alcohols include triethanolamine and N-phenylethanolamine.

[0053] Suitable 8-hydroxyquinoline (hydroxyquinoline for short) includes the following:

[0054] Chemical formula 2:

[0055]

[0056] In the formula, R 1 -R 6 Each is independently hydrogen, halogen, hydroxyl, nitro, amino, C1-C6 alkyl or C1-C6 alkoxy. Examples of hydroxyquinoline include hydroxyquinoline, 5-methylhydroxyquinoline, 5-hydroxyhydroxyquinoline, 5-nitrohydroxyquinoline, 5-aminohydroxyquinoline, 2-methylhydroxyquinoline, and the like, and a combination of at least one of the foregoing hydroxyquinoline. The most preferred hydroxyquinoline includes hydroxyquinoline and 5-methylhydroxyquinoline.

[0057] From about 0.01 to about 25 moles of alkylenediamine ligand, primary monoamine, secondary amine, amino alcohol, and hydroxyquinoline, if present, may be used per 100 moles of monohydric phenol. From about 0.1 to about 1500 moles of tertiary monoamine may be used per 100 moles of monohydric phenol. Suitable concentrations within these ranges may be selected by one skilled in the art without undue experimentation, and the selected concentration may reflect the presence of other reaction components or products, such as water, that affect the efficiency of the catalyst. Suitable molar ratios of the coordinated metal catalyst (measured as moles of metal) to the phenol are from about 1:50 to about 1:400, with about 1:100 to about 1:200 being preferred.

[0058] The complex metal catalyst may optionally also include a halide ion, such as chloride, bromide or iodide. When used, the halide ion in the form of an alkali metal salt or an alkaline earth metal salt may be added to the reaction mixture at a concentration of about 0.1 mol to about 150 mol per 100 mol of phenol monomer.

[0059] In a preferred embodiment, the coordination metal catalyst comprises copper ion, secondary alkylenediamine ligand, secondary monoamine, and tertiary monoamine. In a most preferred embodiment, the coordination metal catalyst comprises copper ion, N,N'-di-tert-butylethylenediamine, di-n-butylamine, and dimethyl-n-butylamine.

[0060] The method may optionally further comprise recovering the coordinated metal catalyst using an aqueous solution. Many different extractants or chelating agents may be used to complex with the catalyst after the polymerization reaction is terminated. For example, sulfuric acid, acetic acid, ammonium salts, bisulfates and various chelating agents may be used. When these substances are added to the reaction solution of the poly(arylene ether), the coordinated metal catalyst is poisoned and no further oxidation occurs. Many different substances may be used, but preferably those chelating agents disclosed in U.S. Pat. No. 3,838,102 to Bennett et al. are used. Useful chelating agents include compounds containing polyfunctional carboxylic acids, such as polyalkylene polyamine polycarboxylic acids, amino polycarboxylic acids, amino carboxylic acids, amino polycarboxylic acids, amino carboxylic acids, polycarboxylic acids and alkali metal salts, alkaline earth metal salts or mixed alkali metal and alkaline earth metal salts thereof. Specific examples of chelating agents include, for example, sodium potassium ammonium tartrate, nitrilotriacetic acid (NTA), citric acid, glycine, ethylenediaminetetraacetic acid (EDTA), hydroxyethylenediaminetriacetic acid, diethylenetriaminepentaacetic acid, salts of the foregoing chelating agents, combinations comprising at least one of the foregoing chelating agents, and the like. Particularly preferred chelating agents include ethylenediaminetetraacetic acid or its mono-, di-, tri-, and tetrasodium salts. The resulting copper coordination can be referred to as copper carboxylate coordination.

[0061] The chelated metal catalyst component can be extracted with water produced in the polymerization reaction by liquid / liquid centrifugation. Alternatively, additional water can be added to the mixture to improve mixing and extraction efficiency. In either case, the chelated metal catalyst component dissolved in the aqueous phase can be separated from the poly(arylene ether) / toluene solution by using liquid / liquid centrifugation. The preferred extraction liquid is an aqueous solution of a lower alkanol, such as a mixture of water and an alkanol having 1 to 4 carbon atoms. Generally, from about 1% to about 80% by volume of the alkanol can be used, based on the total volume of the lower alkanol aqueous solution. The volume ratio of the aqueous liquid extractant to the dispersed organic phase can vary from about 0.01:1 to about 10:1.

[0062] The reaction medium may include an aqueous environment. An antisolvent may also be used in combination with an aqueous medium to aid in the precipitation of the copper (I) species. The selection of a suitable antisolvent is based in part on the solubility coefficient of the copper (I) species being precipitated. Halides are highly insoluble in water, with log (K sp ) values ​​are -4.49, -8.23 and -11.96 respectively. The presence of excess halide ions, due to the formation of CuCl2 - 、CuCl3 2- and CuCl4 3- , and other ligands, which increase solubility in water. Examples of anti-solvents include low molecular weight aliphatic and aromatic hydrocarbons, ketones, alcohols, etc., which themselves have a certain solubility in aqueous solution. If an anti-solvent is used, those skilled in the art will be able to select the appropriate type and amount of anti-solvent.

[0063] The temperature at which the polymerization stage (coupling) is carried out, ie the reaction temperature, is generally about 0 to 95°C.

[0064] Amine groups can be introduced ortho to the hydroxyl moiety of the terminal phenyl group of the polyphenylene ether chain. This is called an "external" amine, and it can include cyclization products, for example, products where a ring is formed between an alkyl substituent on the amine group and a terminal oxy group of the polyphenylene ether chain. A smaller amount of "internal" amine incorporation can also occur within the resin chain. Amine incorporation as used herein refers to a combination of internal and external amines unless otherwise specified. The amount of amine incorporation can be expressed as a weight percentage, based on the total weight of the polyphenylene ether resin, where the weight of the amine includes any substituents that are directly bonded to the amine nitrogen and are derived from the catalyst amine rather than the polyphenylene ether chain. For example, for a polyphenylene ether having the following structure, where the weight of the dibutylamine substituent is 128.4 g / mole and the total weight of the polyphenylene ether molecule is 30287 g / mole, the amount of amine groups introduced is (128.24 / 30287)×100=0.42%.

[0065] Chemical formula 3

[0066]

[0067] In practice, the above-cited White and Nye article may be used. 13 CNMR method, and that described in KP Chan, DS Argyropoulos, DM White, GW Yeager and A Hay, Macromolecules (1994), vol. 27, p6371-6375 13 CNMR and 31 PNMR technique to determine the extent of amine incorporation.

[0068] In one embodiment, the amount of bound amine in the polyphenylene ether can be from about 0.30 to about 2.0 weight percent based on the total weight of the resin. Within this range, at least about 0.40 weight percent, more preferably at least about 0.50 weight percent bound amine based on the total weight of the resin can be preferred. Also within this range, up to about 1.0 weight percent, more preferably up to about 0.70 weight percent bound amine based on the total weight of the resin can be preferred.

[0069] In addition to amines being incorporated into polyphenylene ether resins, other substances may be incorporated during the polyphenylene ether manufacturing process. For example, during the production of poly(2,6-dimethyl-1,4-phenylene ether) (hereinafter referred to as "PPE"), a side reaction may occur resulting in the formation of 3,3`,5,5`-tetramethyl-4,4`-diphenol benzoquinone (hereinafter "TMDPQ"). As shown below, this byproduct is incorporated into PPE in its reduced form.

[0070] Chemical formula 4:

[0071]

[0072] It is hypothesized that the presence of TMDPQ in the reaction mixture may result in a redistribution reaction whereby the external amine groups are relocated to positions within the resin to form internal amine groups.

[0073] In one embodiment, the amount of TMDPQ incorporated into the polyphenylene ether may be about 0.30 to about 2.0 weight percent based on the total weight of the resin. According to the method of the present invention, it is preferred that the PPE produced is prepared in such a way that TMDPQ is not generated as much as possible, specifically, less than 0 to about 0.3 weight percent. More preferably, it is 0 to 0.1 weight percent, and even more preferably, it is 0 to 0.05 weight percent.

[0074] Since TMDPQ is a coloring substance that has an adverse effect on the color of PPE resin products, TMDPQ should be removed as much as possible through redistribution reaction and reduction reaction during the preparation of PPE resin. Here, according to the method of the present invention, PPE resin containing extremely low amount of TMDPQ can be prepared.

[0075] The intrinsic viscosity of the polyphenylene ether formed by the method of the present invention may be about 0.05 to 2.0 dL / g. Within this range, the intrinsic viscosity of the polyphenylene ether used measured in chloroform at 25°C may preferably be about 0.1 dL / g or more, more preferably about 0.2 dL / g or more, further preferably about 0.25 dL / g or more, and particularly preferably about 0.30 dL / g or more. In addition, within this range, the intrinsic viscosity of the polyphenylene ether is preferably about 1.6 dL / g or less, more preferably about 1.0 dL / g or less, further preferably about 0.5 dL / g or less, and particularly preferably about 0.45 dL / g or less.

[0076] In addition, depending on the application of the PPE resin, the intrinsic viscosity of the polyphenylene ether resin used, measured in chloroform at 25°C, is 0.05 to 0.15 dL / g when used as a raw material for a thermosetting resin, and is 0.3 to 0.75 dL / g when used as a raw material for a thermoplastic resin.

[0077] In one embodiment of the method of the present invention, which is particularly suitable for large-scale production of polyphenylene ether, the total monomer concentration in the reaction mixture can be about 10 wt % or more, preferably about 20 wt % or more, and more preferably about 23 wt % or more, based on the total weight of the reaction mixture.

[0078] The polymerization process and reaction conditions such as reaction time and oxygen flow rate can be changed according to the target molecular weight and monomer composition. The polymerization endpoint can be conveniently determined using an online viscometer. Other methods can also be used to determine the molecular weight, implement a specified reaction time, control to a specific end group concentration or oxygen concentration in the solution, etc.

[0079] The method may further include a step of precipitating the polyphenylene ether by adding an anti-solvent to the reaction mixture, or concentrating the reaction mixture and then adding an anti-solvent. The concentration step may also be referred to as pre-concentration, for example, and may be performed after removing the coordinated metal catalyst. The pre-concentration step preferably produces a concentrated solution of about 20 to 60% by weight of the polyphenylene ether. The desired concentration (weight %) of the polyphenylene ether depends on the solvent and the monomer composition and intrinsic viscosity of the polyphenylene ether.

[0080] Any suitable method of pre-concentration may be used. For example, pre-concentration may be performed by preheating the solution to above its atmospheric boiling point at a pressure moderately above 1 atm (so that boiling does not occur in the heat exchanger), followed by flashing the solution to a lower pressure and temperature, thereby causing most of the solvent to evaporate and the heat transferred in the heat exchanger to supply the heat required for evaporation as sensible heat of the solution.

[0081] Suitable antisolvents include lower alkanols having 1 to about 8 carbon atoms, such as methanol, etc.; ketones having 3 to about 10 carbon atoms, such as acetone, etc.; and alkanes having 5 to about 10 carbon atoms, such as hexane, etc.; and combinations containing at least one of the foregoing antisolvents. Preferred antisolvents include methanol. Highly preferred antisolvents include about 70-100% by weight methanol, 0-about 20% by weight toluene, and 0-about 10% by weight water. The antisolvent can be used in a wide range of amounts relative to the amount of organic solvent, wherein the optimal amount depends on the characteristics of the organic solvent and the antisolvent, as well as the concentration, intrinsic viscosity, and monomer composition of the polyphenylene ether product. For example, when the polyphenylene ether is a random copolymer having an intrinsic viscosity of 0.36 dL / g and a composition of 82 wt% 2,6-dimethyl-1,4-phenylene ether units and 18 wt% 2,3,6-trimethyl-1,4-phenylene ether units, the organic solvent is toluene and the anti-solvent is methanol, a toluene:methanol weight ratio of about 1:1.5 to 1:5 is appropriate.

[0082] The method may optionally further comprise separating the precipitated poly(arylene ether) using any conventional filtration or solid / liquid separation technique. Suitable filtration equipment include rotary filters, continuous rotary vacuum filters, continuous moving bed filters, intermittent filters, and the like. Suitable solid / liquid separation devices include continuous solid / liquid centrifuges. It should be noted that solutions of homopolymer poly(2,6-dimethyl-1,4-phenylene oxide) in aromatic solvents such as toluene generally do not exhibit a cloud point. In contrast, when such solutions of poly(2,6-dimethyl-1,4-phenylene oxide) are concentrated, they may form a gel phase, but the dispersed solid particles do not have the characteristics of a cloud point.

[0083] The method may optionally further include a step of washing the filtered polyphenylene ether. Washing is performed, for example, directly on the filter with additional anti-solvent, or by mixing the "powder wet cake" from the filter or the solid / liquid separation device with the additional anti-solvent in a stirred tank. The filtered polyphenylene ether is preferably washed using a two-step re-slurry and solid-liquid separation process flow. In this embodiment, the wet cake from the filter is washed with an anti-solvent in a stirred tank, and then the polyphenylene ether / solvent / anti-solvent mixture is separated using a solid-liquid continuous centrifuge, and the polyphenylene ether wet cake from the centrifuge is mixed again with the anti-solvent through a continuous stirred tank, followed by a second solid-liquid centrifuge for a second solid-liquid separation.

[0084] Example

[0085] The present invention will be specifically described below by way of examples, but the present invention is not limited to the following examples.

[0086] (1) TMDPQ determination method

[0087] The polymerization solution was prepared into a 0.2 weight / volume % chloroform solution according to the polymer standard, and the absorbance at UV wavelength of 420 nm was measured. The absorbance of chloroform was measured as a blank group, and the TMDPQ amount was calculated using the sample amount and the absorption coefficient. TMDPQ (weight %, in PPE) = ((ABS(s)-ABS(0)) × 1.78) / sample amount × sample concentration

[0088] ABS(s): absorbance of the sample; ABS(0) absorbance of chloroform.

[0089] (2)η sp / c determination method

[0090] The polyphenylene ether was prepared into a 0.5 g / dL chloroform solution, and the reduced viscosity (ηsp / c) at 25°C was measured using an Ubbelohde viscometer. The unit is dL / g.

[0091] Example 1

[0092] In this embodiment, a circulation pipeline is provided outside the 30L cylindrical polymerization reactor, and a static mixer (such as Figure 2 As shown, design number: JB / T7660-2016, outer diameter 19mmφ, number of parts 10, total length 300mm, made of SUS316. ), cuprous oxide (Cu2O, 2.7g) dissolved in hydrogen bromide (made into 48wt% aqueous solution 42g) was mixed with N,N′-di-tert-butylethylenediamine (12.0g, DBEDA, CASReg.No.4062-60-6), di-n-butylamine (160g, DBA, CASReg.No.111-92-2), N,N-dimethylbutylamine (255g, DMBA, CASReg.No.927-62-8), tetraalkylammonium chloride surfactant (2.5g, CASReg.No.5137-55-3), 2,6-dimethylphenol (540g) and toluene solvent (14kg). During the polymerization reaction, additional 2,6-dimethylphenol (3.75 kg) was added. During the polymerization, the nitrogen flow rate was set to 6.1 L / min for nitrogen sealing in the gas phase above the polymerization liquid level in the polymerization reactor; the oxygen flow rate was set to 1.07 NL / min·kg-monomer at the gas inlet of the static mixer; here, the oxygen flow rate is the gas flow rate relative to the monomer based on oxygen, for example, when the oxygen is 4.6 NL / min relative to 4.29 kg of monomer, the flow rate of the oxygen-containing gas is 1.07 NL / min·kg-monomer; when the oxygen is 8 NL / min relative to 4.29 kg of monomer, the flow rate of the oxygen-containing gas is 1.86 NL / min·kg-monomer. The temperature was set to rise slowly from 25.0°C to 40.0°C. The linear velocity of the solution passing through the static mixer was set to 3 m / s, and the internal pressure downstream of the static mixer was 0.13 MPa. After the polymerization reaction was completed for 120 minutes, the reactor effluent was mixed with an EDTA·4Na aqueous solution (made into a 5% aqueous solution, 500 g, CAS Reg. No. 13235-36-4, manufactured by Dojin Chemical Research Institute) in order to separate the copper catalyst from the polymer. The two-phase solution was separated using a liquid-liquid centrifuge. The polymer phase was concentrated to 38% by weight by flashing toluene at atmospheric pressure. In a stirred tank container, the concentrated polymer solution (88°C) and methanol (15°C) were mixed at a weight ratio of 1:2 of polymer solution:methanol, and a copolymer product was precipitated from the concentrated polymer solution. The obtained slurry was passed through a rotary vacuum filter, and the wet cake was re-slurried by methanol. The slurry was centrifuged, and the separated solid particles were dried by a rotary paddle dryer.

[0093] In this embodiment, the linear velocity of the solution passing through the static mixer is set to 3 m / s. Although increasing the circulation flow rate can improve the reaction efficiency of oxygen and monomer (monophenol), if the circulation flow rate is too high, unreacted oxygen will enter the polymerization kettle and escape from the reaction solution. Therefore, the circulation flow rate of the external circulation pipeline in the present invention is set to 1.0 to 10.0 m / s. When the circulation flow rate is less than 1.0 m / s, the amount of TMDPQ generated will increase, and when the circulation flow rate is greater than 10.0 m / s, the unreacted oxygen will increase, so it is not preferred.

[0094] In addition, the internal pressure downstream of the static mixer in this embodiment is set to 0.13 MPa, and the internal pressure downstream of the static mixer in the present invention is preferably 0.01 to 0.5 MPa, and more preferably 0.05 to 0.3 MPa. Because when the internal pressure downstream of the static mixer is less than 0.01 MPa, it is difficult to ensure the above-mentioned circulation flow rate, and when the internal pressure downstream of the static mixer is greater than 0.5 MPa, the oxidation reaction is accelerated and the overall reaction temperature is greatly increased, which makes it difficult to control the temperature of the reaction solution.

[0095] Embodiments 2 to 6

[0096] In these examples, polyphenylene ether was polymerized in the same manner as in Example 1 except that the oxygen flow rate was changed to 1.17, 1.28, 1.40, 1.63, and 1.86 NL / min·kg-monomer.

[0097] Embodiments 7 to 12

[0098] In these Examples, polyphenylene ether was polymerized in the same manner as in Examples 1 to 6 except that the polymerization time was 70 minutes.

[0099] Depending on the polymerization time, products with different molecular weights (intrinsic viscosity) can be obtained.

[0100] Comparative Examples 1 and 2

[0101] In Comparative Examples 1 and 2, the oxygen supply rate was set to 1.07NL / min·kg-monomer and 1.17NL / min·kg-monomer, and PPE was polymerized in the same manner as in Example 1, except that the static mixer of the external circulation line was removed and replaced with a single tube of the same size, and a SUS316 single-tube nozzle with an outer diameter of 8mmφ was arranged at the lower part of the agitator in the polymerization kettle.

[0102] Comparative Example 3

[0103] In this example, PPE was polymerized in the same manner as in Example 1 except that the oxygen supply rate was changed to 1.98 NL / min·kg-monomer.

[0104] Table 1

[0105]

[0106]

[0107] In summary, according to the Examples and Comparative Examples, it can be seen that the method of the present invention can produce PPE with a significantly reduced amount of TMDQ generated, as compared with the conventional method.

[0108] Although the present invention is described in detail with preferred embodiments, various changes can be made without departing from the gist of the present invention. In addition, it is also conceivable for those skilled in the art to replace the constituent elements with equivalents. Furthermore, without departing from the gist of the present invention, various appropriate changes can be made to individual situations and materials for the present invention. Therefore, with respect to the present invention, as the best embodiment considered based on the implementation of the invention, it is not limited to the above-mentioned preferred embodiments, and the present invention also includes all embodiments falling within the scope of the patent claims.

Claims

1. A method for preparing a polyphenylene ether resin, characterized in that: In the presence of a solvent and a coordinated metal catalyst, a monohydric phenol is added into a polymerization kettle to form a reaction liquid. The bottom of the polymerization kettle is connected to an external circulation pipeline. During the reaction, the reaction liquid enters the external circulation pipeline from the bottom of the polymerization kettle and is introduced into a static mixer arranged in the circulation pipeline to be mixed with an oxygen-containing gas. Subsequently, the reaction liquid mixed with the oxygen-containing gas is transported back into the polymerization kettle through the external circulation pipeline. The reaction liquid mixed with the oxygen-containing gas is separated to obtain a polyphenylene ether resin. The static mixer is provided with a gas introduction part for introducing the oxygen-containing gas; in the gas introduction part, the flow rate of the oxygen-containing gas is set to 0.5-2.5 NL / min based on the amount of oxygen introduced per kilogram of the monohydric phenol.

2. The method for preparing a polyphenylene ether resin according to claim 1, characterized in that: The oxygen-containing gas is oxygen or a mixture of oxygen and other gases.

3. The method for preparing a polyphenylene ether resin according to claim 2, characterized in that: The oxygen-containing gas is oxygen.

4. The method for preparing a polyphenylene ether resin according to claim 1, characterized in that: In the gas introduction part, the flow rate of the oxygen-containing gas is set to 1.0 to 1.9 NL / min in terms of the amount of oxygen introduced per kg of the monohydric phenol.

5. The method for preparing a polyphenylene ether resin according to claim 1, characterized in that: The linear velocity of the solution passing through the static mixer in the circulation pipeline is 1.0 to 10.0 m / s.

6. The method for preparing a polyphenylene ether resin according to claim 5, characterized in that: The linear velocity of the solution passing through the static mixer in the circulation pipeline is 1.5-8.0 m / s.

7. The method for preparing a polyphenylene ether resin according to claim 6, characterized in that: The linear velocity of the solution passing through the static mixer in the circulation pipeline is 2.0 to 6.0 m / s.

8. The method for preparing a polyphenylene ether resin according to claim 1, characterized in that: The internal pressure downstream of the static mixer is 0.01 to 0.5 MPa.

9. The method for preparing a polyphenylene ether resin according to claim 8, characterized in that: The internal pressure downstream of the static mixer is 0.05-0.3 MPa.

10. The method for preparing a polyphenylene ether resin according to claim 1, characterized in that: Nitrogen was introduced into the polymerization kettle from a nitrogen inlet provided at the top of the polymerization kettle to nitrogen-seal the reaction liquid.

11. The method for preparing a polyphenylene ether resin according to claim 1, characterized in that: The circulation pipeline is also provided with one or more of an online viscometer, a shell-and-tube heat exchanger, a thermometer, and a pressure gauge.

12. A polyphenylene ether resin, characterized in that: Prepared according to the preparation method according to any one of claims 1 to 11, The content of TMDPQ was less than 0.3% by mass based on the total mass of the polyphenylene ether resin polymer solution.

13. The polyphenylene ether resin according to claim 12, characterized in that The content of TMDPQ is less than 0.1 mass %.

14. The polyphenylene ether resin according to claim 13, characterized in that The content of TMDPQ is less than 0.05 mass %.

15. The polyphenylene ether resin according to claim 12, characterized in that: The intrinsic viscosity of the polyphenylene ether resin is 0.05 to 2.0 dL / g.

16. The polyphenylene ether resin according to claim 12, characterized in that The polyphenylene ether resin has an intrinsic viscosity measured in chloroform at 25° C. of 0.05 to 0.15 dL / g when used as a raw material for a thermosetting resin and 0.3 to 0.75 dL / g when used as a raw material for a thermoplastic resin.

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