Method for preparing polyarylsulfone ether on basis of double-end-capping method

Abstract

The present invention relates to a method for preparing polyarylsulfone ether on the basis of a double-end-capping method. In the method, a bifunctional phenol and a bifunctional halogenated arylsulfone are used as raw materials, and are subjected to a condensation polymerization reaction in an organic solvent in the presence of an inorganic caustic alkali or inorganic caustic salt to prepare polyarylsulfone ether. After the molecular weight of the polyarylsulfone ether reaches a preset value, a halogen-eliminating metal phenate end-capping agent is added to a polymerization system, thereby removing an end group of a halogen atom and also achieving control over the molecular weight distribution during polymerization; and after a predetermined molecular weight is reached by means of condensation polymerization, a high-activity metal-phenate-removing aromatic end-capping agent is added to the polymerization system to remove a metal phenate end group and terminate the condensation polymerization reaction, and to make the polyarylsulfone ether have an aromatic end group and also contain necessary functional groups during end-capping. The obtained polyarylsulfone ether not only has good comprehensive performance, but can also meet the subsequent requirements of application fields; and by using end-capping agents containing corresponding functional groups, the requirements of different application scenarios for the polyarylsulfone ether can be met by means of the end-capping reactions.

Description

A method for preparing polyarylsulfoether based on double end-capping method TECHNICAL FIELD

[0001] The present application relates to the technical field of polymer material preparation, in particular to a method for preparing polyarylsulfoether based on double end-capping method. BACKGROUND

[0002] Polyarylsulfoether plastic is a kind of amorphous aromatic thermoplastic polymer plastic containing both arylsulfoether bond (-SO2-) and aryl ether bond in the structure of polymer repeat unit, which is linked by the two types of structures. The polyarylsulfoether plastics of industrial value mainly include polysulfone (English abbreviation: PSF, PSU, PSS, etc., hereinafter represented by PSU), polyether sulfone (English abbreviation: PES), polyphenyl sulfone (English abbreviation: PPSF, PPSU, PPSO, etc., hereinafter represented by PPSU) and polythioether sulfone (English abbreviation: PTES) and the like.

[0003] The sulfoether bond and ether bond in polyarylsulfoether endow the polymer with toughness, transparency and high heat resistance. The sulfoether bond on the main chain makes polyarylsulfoether have rigidity and hardness, and the structure of continuous aromatic ring makes them have high temperature oxidation resistance; on the other hand, the existence of flexible ether bond on the main chain also endows them with toughness and impact resistance. Their heat distortion temperature is 174-221℃, continuous use temperature is in the range of 160-190℃, and especially the continuous use temperature of special varieties is as high as 205℃ or more. This kind of plastic also has intrinsic flame retardant performance, even if it burns, the smoke emission is very little. In addition, this kind of plastic also has high chemical resistance, which can meet the harsh safety requirements. It can be seen that polyarylsulfoether plastic is a kind of special engineering plastic with high thermal stability, good transparency, excellent hydrolytic stability, low molding shrinkage, good biocompatibility, moderate electrical and mechanical properties, excellent resistance to acid, base, alcohol, aliphatic hydrocarbon and salt solution, which can be compared with high-quality engineering plastics such as polyether ether ketone (PEEK) and polyether ketone ketone (PEKK). Especially, the application of polyarylsulfoether plastic in the field of membrane separation such as seawater desalination, IC field ultra-pure water filtration and artificial kidney is outstanding, which highlights its application value.

[0004] However, the preparation of polyarylsulfoether has certain technical difficulties, which restricts its industrial application.

[0005] For example, when using polyarylsulphone ether to prepare ultrafiltration membranes, the most commonly used technology is the solution casting method, which requires dissolving the polyarylsulphone ether plastic in solvents such as dimethylformamide (DMF), dimethylacetamide (DMAc), N-methyl pyrrolidone (NMP), and then casting. This requires the solution of polyarylsulphone ether plastic to be very clear, transparent and stable throughout the processing cycle. Unfortunately, in the prior art, a considerable number of products cannot meet this requirement. In addition, due to the synthesis of polyarylsulphone ether plastic, which is basically a condensation polymerization method using halogen combined with phenolic metal and then removed, one end of the molecular chain always retains halogen, which is extremely disadvantageous for the use of this type of plastic in biological filtration membranes. In addition, the molecular weight distribution of the condensation polymerization process is also difficult to control, so that it is difficult to ensure both the strength of the membrane and the flowability of the membrane during processing, as well as the sufficient ductility of the prepared membrane. In addition, in the synthesis process of polyarylsulphone ether plastic, phenolic metal is also the main functional group of polycondensation, so it is inevitable that a large number of phenolic metal atoms remain at the end of the polyarylsulphone ether molecular chain, which seriously hinders the application of polyarylsulphone ether membranes in the field of ultra-pure water filtration in the IC industry. In addition, some applications in the field of membrane separation require not only to maintain the intrinsic properties of polyarylsulphone ether and its stability in solution, but also to have different permeability requirements for certain substances for different application occasions, so some modifications need to be made to the structure of the polyarylsulphone ether molecule. These problems naturally attract the attention of the scientific and industrial communities and efforts are made to change this situation.

[0006] For example, Chinese patent CN 116218220A discloses a polyphenylsulphone composition, which comprises the following components by weight parts: polyphenylsulphone resin 95-99 parts; polyaramid liquid crystal polymer 0.1-5 parts; acid absorber 0.05-0.3 parts; wherein the polyphenylsulphone resin comprises the following monomers and their homologues by mole percentage: 4,4'-diphenol 10-35 mol%; amide group-containing bisphenol monomer 15-40 mol%; 4,4'-dichlorodiphenylsulphone 45-55 mol%. The main innovation of this scheme is to add 0.1-5 parts of polyaramid liquid crystal polymer to the polymerization monomer to copolymerize, in order to increase the hydrophilic property of polyphenylsulphone, and add 0.15% of acid absorber to simplify the polycondensation process. However, it does not make a clear contribution to forming a clear, transparent and stable polyarylsulphone ether plastic solution, controlling the molecular weight distribution and eliminating the presence of phenolic metal residues.

[0007] Chinese patent CN 116589680 A discloses a method for preparing aromatic polymers, which includes condensation polymerization of halogenated monomers and second monomers in the presence of a base, a solvent and a water absorbent, wherein the second monomers include phenol monomers, thiophenol monomers or amine monomers. The main innovation of this scheme is that the types of monomers are not limited to only using phenolic groups, but also can use thiophenolic groups or amine groups; and not limited to using dichlorobenzene sulfone, various chlorobenzene sulfones can be used, and even fluorobenzene sulfone can be used. In addition, a water absorbent is added during the reaction. It is considered that using cheap and easily available water absorbent to absorb water generated during polymerization not only eliminates the need to add water-removing agents and water-removing processes, but also reduces the non-soluble solid content, thereby realizing the synthesis of a series of aromatic polymers at low cost and high efficiency. However, this scheme does not make a clear contribution to forming a clear, transparent and stable polysulfone ether plastic solution, and how to control the molecular weight distribution and eliminate phenolic metal residues.

[0008] In addition, in the end-capping technology, the technology disclosed by Li Shengzhu and Wu Cunlei in the book "Sulfone Polymers and Their Applications" is to use chloromethane to cap the end groups. However, since the boiling point of chloromethane is much lower than the temperature of the condensation polymerization reaction, most of the chloromethane will inevitably be released into the gas phase during the polymerization process, not only failing to achieve the end-capping effect, but also causing environmental pollution by escaping into the air. SUMMARY

[0009] The purpose of the present application is to overcome the defects of the existing preparation technology of polyarylsulfone ether and provide a method for preparing polyarylsulfone ether based on a double end-capping method.

[0010] The halogen-eliminating phenolic metal end-capping agent used in the present application is added to the system when the condensation polymerization reaches a predetermined stage, which not only eliminates the end groups of halogen atoms that are not suitable for some applications, but more importantly, can control the molecular weight distribution of polyarylsulfone ether as needed, so that the polyarylsulfone ether not only meets the requirements for strength, but also ensures the flowability during processing and the requirements for sufficient ductility after film formation.

[0011] In addition, after the condensation polymerization reaches a predetermined molecular weight, the high-activity phenolic metal-removing aromatic end-capping agent is used to terminate the polymerization reaction, which not only quickly terminates the polymerization reaction and avoids the low-boiling-point end-capping agent from being discharged into the air to cause pollution, but also does not affect the heat resistance of polyarylsulfone ether, and removes the phenolic metal end groups that are not desired to exist. More importantly, the stability of the solution can be further improved according to the different solvents used for preparing ultrafiltration membranes from polyarylsulfone ether, and the selective permeability of certain substances can be achieved through the functional groups contained in the high-activity phenolic metal-removing aromatic end-capping agent according to the different application fields, so that the application range of the ultrafiltration membranes prepared from polyarylsulfone ether is more extensive.

[0012] The object of the present application can be achieved by the following technical solutions.

[0013] The present application provides a method for preparing polyarylsulfonyl ether based on double end-capping method, comprising the following steps:

[0014] S1, salt formation and polycondensation reaction: taking difunctional phenol and difunctional halogenated aryl sulfone as raw materials, condensation polymerization reaction is carried out in the presence of inorganic caustic alkali or inorganic caustic salt in organic solvent, the inorganic caustic alkali or inorganic caustic salt first reacts with the difunctional phenol to form phenate, then reacts with halogen atom, removes halide alkali metal salt, and forms polycondensation product polyarylsulfonyl ether;

[0015] S2, control of molecular weight distribution of polyarylsulfonyl ether: after the molecular weight of polyarylsulfonyl ether reaches a predetermined value, a halogen-removing phenol metal end-capping agent is added to the polymerization system, and the end groups of halogen atoms are gradually removed by reaction, so that only the other end of the molecule chain that has been capped can carry out chain growth reaction, and the molecule chain that has not been capped can still continue chain growth reaction in both directions, thereby realizing control of the polymerization molecular weight distribution through the sequence of capping before and after;

[0016] S3, termination of condensation polymerization reaction: after the condensation polymerization reaches a predetermined molecular weight, a high-activity phenol-removing aromatic end-capping agent is added to the polymerization system to remove the phenol metal end group and terminate the condensation polymerization reaction, so that the polyarylsulfonyl ether not only has aromatic end groups, but also contains necessary functional groups, that is, by using a high-activity phenol-removing aromatic end-capping agent, the polyarylsulfonyl ether is provided with corresponding functional groups through a simple end-capping reaction.

[0017] In an embodiment of the present application, the amount of the difunctional phenol and the difunctional halogenated aryl sulfone is in a molar ratio of (0.8-1.1):1 of phenol to halogen, preferably in a molar ratio of 1:1 of phenol to halogen.

[0018] In an embodiment of the present application, the difunctional phenol is selected from one or a combination of the following structural formulas:

[0019]

[0020] In an embodiment of the present application, the difunctional halogenated aryl sulfone is selected from one or a combination of the following structural formulas:

[0021]

[0022] In an embodiment of the present application, the equivalent number of the inorganic caustic alkali or inorganic caustic salt is 1-1.5 times the equivalent number of phenol.

[0023] In one embodiment of the present application, the inorganic caustic or inorganic caustic salt is selected from one or a combination of several of the following:

[0024] LiOH, NaOH, KOH, CsOH, Na2O, Na2CO3, K2CO3, Cs2CO3, NaHCO3, KHCO3, CsHCO3, Li3PO4, Na3PO4, K3PO4, Cs3PO4, Na2HPO4, Cs2HPO4, or K2HPO4.

[0025] In one embodiment of the present application, the organic solvent is selected from one or a combination of several of the following: dimethylformamide, dimethylacetamide, dimethylsulfoxide, sulfolane, N-methylpyrrolidone, cyclohexanone.

[0026] In one embodiment of the present application, the theoretical amount of the halogen-eliminating phenolic metal-based capping agent and the high-activity phenolic metal-eliminating aromatic capping agent are both shown in formula (1)

[0027]

[0028] wherein: W is the amount of capping agent, in units of weight, which can be one of grams, kilograms, tons, etc.; M is the set molecular weight of the polyarylsulfonyl ether; V is the mass of the theoretical repeating unit of the polyarylsulfonyl ether; N is the number of raw materials of the used difunctional phenol and difunctional sulfone converted into the structure of the theoretical repeating unit; Q is the mass of the added functional groups after complete capping of both ends of the polyarylsulfonyl ether; and C is the molar mass of the capping agent. The units of M, V, Q, and C must all be the same as W, which means that when W is in units of grams, the molecular weight of the polyarylsulfonyl ether must be in units of grams, and the rest are analogously true.

[0029] In one embodiment of the present application, the halogen-eliminating phenolic metal-based capping agent is selected from one or several of the following structural formulas:

[0030]

[0031] In one embodiment of the present application, the high-activity phenolic metal-eliminating aromatic capping agent is selected from one or several of the following structural formulas: wherein n is a natural number from 0 to 16:

[0032]

[0033] In one embodiment of the present application, during the salt formation and polycondensation reaction of step S1, an inert gas such as Ar or N2 is used for gas-phase protection.

[0034] In one embodiment of the present application, during the salt formation and condensation polymerization in step S1, the reaction by-products water and alkali metal halide are also removed simultaneously to gradually increase the molecular weight of the polyaryl sulfone ether. During the salt formation and condensation polymerization in step S1, two molecules of end groups form water and alkali metal halide, and after the reaction by-products are removed, the remaining portions bond to each other to form macromolecules.

[0035] In one embodiment of the present application, in steps S2 and S3, the method for determining whether the molecular weight of the polyaryl sulfone ether reaches a predetermined value is to continuously sample during the polymerization, test the viscosity of the obtained sample in a fixed solvent and concentration, and determine the molecular weight of the polyaryl sulfone ether according to the viscosity.

[0036] Compared with the prior art, the advantages and beneficial effects of the present application are embodied in the following aspects:

[0037] 1) Since the synthesis of the polyaryl sulfone ether is basically a condensation polymerization method in which one halogen atom of a di-functional halogen-containing aryl sulfone and one phenyl metal atom of a di-functional phenyl metal are combined and removed, and the molecular chains removed simultaneously bond to each other, one end group of the molecular chain still retains one halogen atom, which is extremely unfavorable for use as a biological filtration membrane. In addition, the molecular weight distribution during the condensation polymerization process is difficult to control, so that it is difficult to ensure that the product or membrane has sufficient strength, and it is also difficult to ensure that the processing fluidity and the product or membrane have sufficient ductility. In the classical synthesis method, the halogen atom remaining at one end of the polyaryl sulfone ether molecular chain is left as it is, and the molecular weight distribution during the condensation polymerization process cannot be controlled. However, in the present application, when the polymerization reaches a predetermined molecular weight, a halogen-eliminating phenyl metal end-capping agent for capping the aryl halogen end group is added, which gradually eliminates the halogen end group on one hand, and on the other hand, the molecular chain that has lost the halogen end group can only have the other end for chain growth reaction, while the molecular chain that has not been capped can still continue the chain growth reaction in both directions, thus achieving the requirement of expanding the molecular weight distribution;

[0038] 2) In the synthesis of poly (aryl sulfone ether), in addition to the elimination of the above-mentioned halogen for end-capping, the other end group is the functional group of phenolic metal, so it is inevitable that a large amount of phenolic metal remains at the terminal of the poly (aryl sulfone ether) molecular chain. This seriously hinders the application of poly (aryl sulfone ether) film in the field of ultra-pure water filtration in the IC field, and causes the solution to be unstable in the film forming process. Although there are examples of using chloromethane for end-capping in the classical synthesis method, but because the boiling point of chloromethane is much lower than the polymerization temperature, it is inevitable to escape to the atmosphere, not only the utilization rate is very low, cannot be measured, but also these toxic gases pollute the environment. The technical scheme provided in the application uses a high-activity phenol metal-removing aromatic end-capping agent with a boiling point higher than the polymerization temperature, which not only has high utilization rate and can be accurately measured, but also avoids environmental pollution. More importantly, on the one hand, the aromatic end group is conducive to improving the heat stability of poly (aryl sulfone ether), and on the other hand, according to the needs of the application scene, the corresponding functional groups can be bonded;

[0039] 3) In the application field of poly (aryl sulfone ether) membrane separation, firstly, the film forming solution is required to be relatively stable, secondly, in addition to ensuring the intrinsic properties of poly (aryl sulfone ether), it is also required to have different selectivity permeability to certain substances for different application occasions, so some modifications need to be made to the molecular structure of poly (aryl sulfone ether). For example, it is required to improve the hydrophilicity, carbonyl affinity, amide affinity, etc. in some application occasions. In the classical polymerization technology, the method of adding other monomers for copolymerization is usually adopted, which often changes the intrinsic properties of poly (aryl sulfone ether), and the effect is not as good as the mobile end group. As described above in 2, the high-activity phenol metal-removing aromatic end-capping agent containing the corresponding functional group is used to eliminate the phenol metal, and at the same time, the desired predetermined target is achieved through a simple end-capping reaction. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 is the FTIR ATR infrared spectrum of the poly (aryl sulfone ether) granules in Comparative Example 2;

[0041] Figure 2 is the GPC curve of the molecular weight and its distribution of the poly (aryl sulfone ether) granules in Comparative Example 2. DETAILED DESCRIPTION

[0042] The application will be described in detail below in combination with the drawings and specific examples.

[0043] Comparative Example 1:

[0044] In a 50L pilot plant reactor equipped with a rectification device, 20 moles of biphenyl-dihydroxy, 24 moles of sodium carbonate, 20.05 moles of dichlorodiphenyl sulfone, and 27.5L of N-methyl pyrrolidone as solvent were added one by one while the stirrer was turned on at a speed of 100r / min and pure nitrogen was introduced for gas phase protection. Then the heater for circulating heat transfer oil in the reactor jacket was turned on and the temperature was gradually increased. When the temperature reached 180℃, it was maintained for 2h to complete the salt formation reaction. Then the temperature was increased to 203℃ and the reflux ratio R of the rectification device was maintained at about 1.1, and the by-product water was removed while the polymerization was carried out, and the reaction was continued for 5-6h. Until the rotational viscosity of the melt in 25%(mass percentage, the same below) dimethylacetamide solution at 40℃ reached 3100mPa·s(measured by rotational viscometer, the same below)(i.e. the molecular weight of polyarylsulfonyl ether reached the predetermined value), the heating and stirring were stopped, and the polymerization system was allowed to cool naturally while the polymer solution was allowed to stand and precipitate. When the system dropped to 120℃, it was maintained at constant temperature until the polymer solution precipitated out of the by-product salt, sodium chloride, and the upper layer showed a clear solution, and then the upper clear polymer solution was separated and removed.

[0045] The upper clear polymer solution was concentrated, part of the solvent was extracted, and then the concentrated solution was recycled to grind into a fine powder and mixed with water, and after centrifugal separation, the water was filtered out, and then the screw belt dryer was used to dry at 170℃ under reduced pressure to obtain the dry powder of polyarylsulfonyl ether. Then under the protection of antioxidant, a φ 35, L / D = 40 co-rotating parallel twin-screw extruder was used to granulate at temperature settings of 150℃, 200℃, 225℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 300℃ to obtain the granules of polyarylsulfonyl ether. The performance test is shown in Table 1.

[0046] Comparative Example 2:

[0047] Similar to Comparative Example 1, 20 moles of bisphenol A, 24 moles of potassium carbonate, 20.05 moles of dichlorodiphenyl sulfone, and 27.5 L of N-dimethylacetamide as solvent were added one by one in a 50 L pilot reaction kettle equipped with a rectification device, while the stirrer was turned on at a speed of 100 r / min, and pure nitrogen was introduced for gas phase protection. Then the heater for circulating heat conduction oil in the jacket of the reaction kettle was turned on, and the temperature was gradually increased. When the temperature reached 140℃, it was maintained for 3 h, and the salting reaction was completed. Then the temperature was increased to 165℃, and the reflux ratio R of the rectification device was maintained at about 1.1, while removing the byproduct water, and the polymerization was carried out for 5-6 h. Until the rotational viscosity of the melt in 25% dimethylacetamide solution at 40℃ reached 2800 mPa·s, the heating and stirring were stopped, and the polymerization system was allowed to cool naturally, and the polymer solution was allowed to stand and precipitate. When the system dropped to 120℃, it was maintained at a constant temperature, until the polymer solution precipitated out of the byproduct salt, potassium chloride, and the upper layer showed a clear solution, and then the upper clear polymer solution was separated and taken out.

[0048] The upper clear polymer solution was extracted to remove part of the solvent, and then the concentrated solution was ground into a fine powder in deionized water, and after centrifugal separation, the water was filtered out, and then the polymer dry powder of polyarylsulfone ether was obtained by drying in a screw belt dryer at 170℃ under reduced pressure. Then under the protection of an antioxidant, granulation was carried out using a φ 35, L / D = 40 co-rotating parallel twin-screw extruder at temperature settings of 150℃, 200℃, 225℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 300℃, to obtain granules of polyarylsulfone ether. The performance test is shown in Table 1, and the FTIR ATR infrared spectrum and the GPC curve of the molecular weight and distribution are shown in Figures 1 and 2, respectively.

[0049] Example 1:

[0050] ​Similar to Comparative Example 2, 20 moles of bisphenol A, 24 moles of potassium carbonate, 20.05 moles of dichlorodiphenyl sulfone, and 27.5 L of N-dimethylacetamide as solvent were added one by one in a 50 L pilot reaction kettle equipped with a rectification device, while the stirrer was turned on at a speed of 100 r / min, and pure nitrogen was introduced for gas phase protection. Then the heater for circulating heat conduction oil in the jacket of the reaction kettle was turned on, and the temperature was gradually increased. When the temperature reached 140℃, it was maintained for 3 h, and the salting reaction was completed. Then the temperature was increased to 165℃, and the reflux ratio R of the rectification device was maintained at about 1.1, while removing the byproduct water, and the polymerization was continued for 5-6 h. When the rotational viscosity of the melt in 25% dimethylacetamide solution at 40℃ reached 2400 mPa·s, 25.31 g of potassium phenol was added according to formula (1), and the reaction was continued for 2-3 h. When the rotational viscosity of the melt in 25% dimethylacetamide solution at 40℃ reached 2800 mPa·s, the heating and stirring were then stopped, and the polymerization system was allowed to cool naturally while the polymer solution was allowed to settle. When the system was cooled to 120℃, the temperature was maintained until the polymer solution was precipitated with the byproduct salt, potassium chloride, and the upper layer became a clear solution, and then the upper clear polymer solution was separated and removed.

[0051] The upper clear polymer solution was concentrated, and part of the solvent was extracted. The concentrated solution was then ground into a fine powder in deionized water, and the water was filtered out by centrifugation. The polymer dry powder of polyarylsulfone ether was obtained by drying at 170℃ under reduced pressure using a screw belt dryer. Then the The pellet of polyarylsulfone ether was obtained by granulating under the protection of antioxidant using a φ 35, L / D = 40 co-rotating parallel twin-screw extruder at temperature settings of 150℃, 200℃, 225℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 300℃. The performance test is shown in Table 1.

[0052] Example 2:

[0053] Similar to Example 1, 20 moles of bisphenol A, 24 moles of potassium carbonate, 20.05 moles of dichlorodiphenyl sulfone, and 27.5 L of N-dimethylacetamide as solvent were added one by one in a 50 L pilot reaction kettle equipped with a rectification device, while the stirrer was turned on at a speed of 100 r / min, and pure nitrogen was introduced for gas phase protection. Then the heater for circulating heat conduction oil in the jacket of the reaction kettle was turned on, and the temperature was gradually increased. When the temperature reached 140℃, it was maintained for 3 h, and the salt formation reaction was completed. Then the temperature was increased to 165℃, and the reflux ratio R of the rectification device was maintained at about 1.1, and the by-product water was removed while polymerizing, and the reaction was continued for 4-6 h. Until the rotational viscosity of the melt in 25% dimethylacetamide solution at 40℃ reached 2400, 25.31 g of potassium phenol was added according to formula (1), and the reaction was continued for 2-3 h. Until the rotational viscosity of the melt in 25% dimethylacetamide solution at 40℃ reached 2800 mPa·s, 38.81 g of biphenyl benzyl chloride was added to the reaction kettle according to formula (1), and the reaction was continued for 2 h. Then the heating and stirring were stopped, and the polymer solution was allowed to naturally cool while the polymer solution was allowed to settle. When the system dropped to 120℃, it was maintained at a constant temperature until the polymer solution precipitated the by-product salt, potassium chloride, and the upper layer became a clear solution. The upper clear polymer solution was concentrated, the solvent was extracted, and the concentrated solution was ground into a fine powder in deionized water, and the water was filtered out by centrifugal separation, and then dried at 170℃ under reduced pressure using a screw belt dryer to obtain a dry powder of polyarylsulfone ether. Then the dry powder was granulated at φ 35, L / D = 40, and the same direction parallel twin-screw extruder was used under the protection of antioxidant 168 at temperature settings of 150℃, 200℃, 225℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 300℃ to obtain granules of polyarylsulfone ether. The performance test is shown in Table 1.

[0054] The upper clear polymer solution was concentrated, the solvent was extracted, and the concentrated solution was ground into a fine powder in deionized water, and the water was filtered out by centrifugal separation, and then dried at 170℃ under reduced pressure using a screw belt dryer to obtain a dry powder of polyarylsulfone ether. Then the dry powder was granulated at φ 35, L / D = 40, and the same direction parallel twin-screw extruder was used under the protection of antioxidant 168 at temperature settings of 150℃, 200℃, 225℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 300℃ to obtain granules of polyarylsulfone ether. The performance test is shown in Table 1. 1790 / 168anti-oxidant protection, using a φ 35, L / D = 40 co-rotating parallel twin-screw extruder, granulating at temperature settings of 150℃, 200℃, 225℃, 250℃, 260℃, 270℃, 280℃, 290℃, 300℃, 300℃, to obtain granules of polyarylsulfone ether. The performance test is shown in Table 1.

[0055] Example 3:

[0056] Similar to Example 2, 18.4 moles of bisphenol A, 1.6 moles of N, 1-di-p- phenylcarboxamide, 24 moles of potassium carbonate, 20.05 moles of dichlorodiphenyl sulfone, and 27.5 L of N-dimethylacetamide as solvent were added one by one into a 50 L pilot plant reactor equipped with a rectification device, while the stirrer was turned on at a speed of 100 r / min and pure nitrogen was introduced for gas phase protection. Then the heater for circulating heat conduction oil in the reactor jacket was turned on, and the temperature was gradually increased. When the temperature reached 140°C, the salification reaction was completed after maintaining for 3 h. Then the temperature was increased to 165°C, and the reaction was continued for 3-6 h while removing the byproduct water and maintaining the reflux ratio R of the rectification device at about 1.1. When the rotational viscosity of the melt in 25% dimethylacetamide solution at 40°C reached 2600 mPa·s, 25.31 g of potassium phenoxide was added according to Formula (1), and the reaction was continued for 2-3 h. When the rotational viscosity of the melt in 25% dimethylacetamide solution at 40°C reached 3000 mPa·s, 47.05 g of N-p-benzylchloro, 1-phenylcarboxamide was added to the reactor according to Formula (1), and the reaction was continued for 2 h. Then the heating and stirring were stopped, and the polymer solution was allowed to naturally cool down while being left to stand and precipitate. When the system was cooled to 120°C, the temperature was maintained until the polymer solution was precipitated out of the byproduct salt, potassium chloride, and the upper layer became a clear solution. The upper clear polymer solution was concentrated, and the solvent was removed therefrom. The concentrated solution was then ground into a fine powder in deionized water, and the water was filtered out by centrifugation. The polymer dry powder was obtained by drying at 170°C under reduced pressure using a screw belt dryer.

[0057] The upper clear polymer solution was concentrated, and the solvent was removed therefrom. The concentrated solution was then ground into a fine powder in deionized water, and the water was filtered out by centrifugation. The polymer dry powder was obtained by drying at 170°C under reduced pressure using a screw belt dryer. 1790 / 168The granules of the polyarylsulfone ether were obtained by granulating under the protection of an antioxidant using a φ 35, L / D = 40 co-rotating parallel twin-screw extruder at temperature settings of 150°C, 200°C, 225°C, 250°C, 260°C, 270°C, 280°C, 290°C, 300°C, and 300°C. The performance tests of the granules are shown in Table 1.

[0058] Table 1 Performance of the granules of the polyarylsulfone ether of the comparative example and the examples

[0059]

[0060] In Table 1, wherein: Tensile property: test method refers to GB / T 1040.2-2006 (type 1A); Flexural property: test method refers to GB / T 9341-2008; Impact strength: test method refers to GB / T 9341-2008; Glass transition temperature: test method refers to ASTM D3418-15; Dielectric constant: test method refers to ASTM D150-18; Dielectric strength: test method refers to ASTM D150-18; Contact angle: test method refers to GB / T 30447-2013; Metal content: atomic spectroscopy; Chlorine content: elemental analysis.

[0061] As can be seen from FIG. 1, FIG. 2 and Table 1, according to the method of the present application, the predetermined polyarylsulphone polymer can be obtained whether it is a comparative example or an embodiment. Especially in the embodiment, after the elimination and blocking of the halogen end group, not only the content of halogen is reduced by several tens of times, but also by carrying out the end-capping reaction at the predetermined degree of polymerization, the molecular weight distribution can be effectively expanded. Thus, the elongation at break of the resin and the ductility of the product are greatly improved. This is extremely advantageous for the application of the polyarylsulphone polymer in the field of membrane filtration.

[0062] Secondly, by eliminating and blocking the phenolic metal end group, the content of alkali metal is also reduced by more than several tens of times, which will be very advantageous for the application of the polyarylsulphone membrane in the field of ultra-pure water filtration in the IC industry.

[0063] Furthermore, by eliminating and blocking the phenolic metal end group, functional functional groups such as amide, hydroxyl or carbonyl are introduced to meet the needs of polyarylsulphone membranes for filtering different compounds in various application fields. For example, in Example 3, by eliminating the phenolic metal and bonding the aromatic end group containing amide group, the hydrophilicity, especially the amide affinity, is greatly improved compared to Example 2. Therefore, it will greatly improve the permeability of urea and other waste in the application of kidney dialysis membrane separation of polyarylsulphone membrane.

[0064] In addition, using dimethylformamide, which is the most widely used solvent in the membrane making process, as the solvent, the pellets in the above examples and comparative examples are mixed into a commonly used 18% concentrated solution, and the time for them to maintain a clear, transparent and stable solution is observed, and the results are shown in Table 2.

[0065] Table 2 Stability observation of solution prepared from pellets in examples and comparative examples

[0066]

[0067] It can be clearly seen that the conventional synthesis method can obtain the polyarylsulphone ether polymer with the molecular weight and mechanical property meeting the application requirements, but it is difficult to meet the requirements of the film forming process. However, the double-terminated technology in the application can not only meet the requirements of the solution storage period in the film forming process (see Example 3), but also greatly reduce the content of halogen and alkali metal in the polyarylsulphone ether, and can meet the requirements of the application field on the molecular weight distribution of the polyarylsulphone ether polymer according to different use occasions.

[0068] The above description of the examples is for the purpose of facilitating the understanding and use of the application by those skilled in the art. Those skilled in the art can obviously make various modifications to the examples and apply the general principles described herein to other examples without creative labor. Therefore, the application is not limited to the above examples, and the improvements and modifications made by those skilled in the art according to the disclosure of the application without departing from the scope of the application should be within the protection scope of the application.

Claims

1. A method for preparing polyaryl sulfone ether based on a double end-capping method, characterized in that: The following steps are involved: S1. Salt formation and polycondensation reaction: using difunctional phenol and difunctional halogenated aromatic sulfone as raw materials, a condensation polymerization reaction is carried out in an organic solvent in the presence of an inorganic caustic alkali or an inorganic caustic salt, wherein the inorganic caustic alkali or the inorganic caustic salt first reacts with the difunctional phenol to form a phenol metal salt, which then reacts with a halogen atom to remove the halogenated alkali metal salt and form a polycondensation product, a polyaryl sulfone ether; S2. Control of the molecular weight distribution of polyarylsulfone ether: After the molecular weight of the polyarylsulfone ether reaches a predetermined value, a halogen-eliminating phenol metal end-capping agent is added to the polymerization system to gradually remove the end groups of the halogen atoms through reaction, so that only the other end of the end-capped molecular chain can undergo chain growth reaction, while the unend-capped molecular chain can still continue the chain growth reaction in both directions at both ends, thereby achieving control of the polymerization molecular weight distribution by the order of end-capping; S3. Termination of condensation polymerization reaction: After the condensation polymerization reaches a predetermined molecular weight, a highly active phenol-removing metal aromatic end-capping agent is added to the polymerization system to remove the phenol metal end groups and terminate the condensation polymerization reaction. In the end-capping process, not only the polyaryl sulfone ether has aromatic end groups, but also contains necessary functional groups.

2. The method for preparing polyaryl sulfone ether based on a double end-capping method according to claim 1, characterized in that: The usage ratio of the difunctional phenol and the difunctional halogenated aromatic sulfone is as follows: the molar ratio of phenol to halogen is (0.8-1.1):

1.

3. The method for preparing polyaryl sulfone ether based on a double end-capping method according to claim 1, characterized in that: The difunctional phenol is selected from one or more combinations of the following structural formulas:

4. The method for preparing polyaryl sulfone ether based on a double end-capping method according to claim 1, characterized in that: The difunctional halogenated aromatic sulfone is selected from one or more combinations of the following structural formulas:

5. The method for preparing polyaryl sulfone ether based on a double end-capping method according to claim 1, characterized in that: The equivalent number of the inorganic caustic alkali or inorganic caustic salt is 1-1.5 times the equivalent number of phenol; The inorganic caustic alkali or inorganic caustic salt is selected from one or a combination of the following substances: LiOH, NaOH, KOH, CsOH, Na2CO3, K2CO3, Cs2CO3, NaHCO3, KHCO3, CsHCO3, Li3PO4, Na3PO4, K3PO4, Cs3PO4, Na2HPO4, Cs2HPO4 or K2HPO4.

6. The method for preparing polyaryl sulfone ether based on a double end-capping method according to claim 1, characterized in that: The theoretical dosage of the halogen-eliminating phenol metal end-capping agent and the high-activity phenol-eliminating metal aromatic end-capping agent are shown in formula (1): ; Wherein: W is the amount of the end-capping agent used, in units of weight; M is the set molecular weight of the polyarylsulfone ether; V is the mass of the theoretical repeating unit of the polyarylsulfone ether; N is the number of the difunctional phenol and difunctional sulfone raw materials used converted into the theoretical repeating unit structure; Q is the mass of the functional groups added after the two ends of the polyarylsulfone ether are completely capped; C is the molar mass of the end-capping agent.

7. The method for preparing polyaryl sulfone ether based on a double end-capping method according to claim 1, characterized in that: The halogen-eliminating phenol metal end-capping agent is selected from one or more of the following structural formulas:

8. The method for preparing polyaryl sulfone ether based on a double end-capping method according to claim 1, characterized in that: The highly active phenol removal metal aromatic end-capping agent is selected from one or more of the following structural formulas: wherein n is a natural number of 0-16:

9. The method for preparing polyaryl sulfone ether based on a double end-capping method according to claim 1, characterized in that: During the salt formation and polycondensation reaction in step S1 , the reaction by-products water and alkali metal halide are also removed simultaneously, so that the molecular weight of the polyaryl sulfone ether is gradually increased.

10. The method for preparing polyaryl sulfone ether based on a double end-capping method according to claim 1, characterized in that: During the salt formation and polycondensation reaction in step S1, an inert gas is used for gas phase protection; In step S2 and step S3, the method for determining whether the molecular weight of the polyarylsulfone ether reaches a predetermined value is: continuously sampling during the polymerization process, testing the viscosity of the obtained samples in a fixed solvent and concentration, and determining the molecular weight of the polyarylsulfone ether based on the viscosity.

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