A polysulfone resin and its preparation method and application, a composite reverse osmosis membrane

Abstract

The present invention relates to the technical field of polysulfone resins, and in particular to a polysulfone resin, a preparation method and application thereof, and a composite reverse osmosis membrane. The present invention provides a polysulfone resin having a structure shown in Formula I. The polysulfone resin provided by the present invention further modifies the end of the overall chain segment of the polysulfone resin by introducing an active functional group (R3 group), introducing an NH2 group or a SO3 group at the ortho, meta or para position of phenol, ‑ Na + The highly active terminal functional groups can significantly improve the permeability of polysulfone resins. At the same time, the highly active terminal functional groups also significantly improve the surface activity of polysulfone resins, and the intermolecular forces with materials such as polyimide and polyurethane are stronger and tighter, and the binding ability is enhanced. The results of the examples show that the polysulfone resin provided by the present invention as the base membrane has significantly improved permeability to water molecules, and the permeation flux can reach 33.88L / (m 2 ·h·bar).

Description

Technical Field

[0001] The invention relates to the technical field of polysulfone resins, and in particular to a polysulfone resin and a preparation method and application thereof, and a composite reverse osmosis membrane. Background Art

[0002] Polysulfone resin is a high-performance engineering plastic. Due to its heat resistance, hot water resistance, creep resistance, dimensional stability, impact resistance, chemical resistance, non-toxicity and flame retardancy, it is widely used in electronics, electrical appliances, machinery, automobiles, medical devices, food processing and non-stick coatings.

[0003] At present, polysulfone resins have a huge application market and broad prospects in the field of semipermeable membrane applications, especially as the base membrane of composite reverse osmosis membranes. Polysulfone resins are widely used due to their simple membrane preparation, good mechanical strength, good pressure resistance, stable chemical properties, non-toxicity, and resistance to biodegradation.

[0004] However, when polysulfone resins are used in membrane-level applications such as reverse osmosis membranes, medical hemodialysis membranes, and seawater desalination membranes, reverse osmosis membranes using polysulfone resins as base membranes are prone to leakage, low osmotic efficiency, and excessive osmotic pressure differences. Summary of the invention

[0005] The purpose of the present invention is to provide a polysulfone resin and a preparation method and application thereof, and a composite reverse osmosis membrane. The polysulfone resin provided by the present invention has strong surface permeability and has good bonding ability with other materials (polyimide, polyurethane, etc.) when used as a reverse osmosis membrane base membrane, so that the integrity of the reverse osmosis membrane is enhanced and leakage caused by separation between layers is avoided.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a polysulfone resin having a structure shown in Formula I:

[0008]

[0009] The n is 50 to 220;

[0010] The R1 is

[0011] The R2 is

[0012] R3 is -NH2 or -SO3 - Na + .

[0013] Preferably, it has a structure shown in any one of Formula I-1, Formula I-2, Formula I-3 and Formula I-4:

[0014]

[0015] In the formula I-1, formula I-2, formula I-3 and formula I-4, n is independently 50 to 220.

[0016] The present invention provides a method for preparing the polysulfone resin described in the above technical solution, comprising the following steps:

[0017] In a protective atmosphere, phenolphthalein, a dihalogen double-end monomer, a polar organic solvent, an initiator and a water-separating agent are mixed to perform a salt-forming reaction to obtain a salt-forming reaction liquid;

[0018] The salt-forming reaction solution and the end-capping agent are mixed to carry out polymerization reaction to obtain a polysulfone resin;

[0019] The dihalogen double-end monomer is 4,4'-dihalogenated diphenyl sulfone or 4,4'-dihalogenated dibenzophenone;

[0020] The end-capping agent is aminophenol or hydroxybenzene sulfonate.

[0021] Preferably, the molar ratio of the end-capping agent to the dihalogenated double-end monomer is (0.5-5):100.

[0022] Preferably, the polymerization reaction temperature is 210-230° C., and the polymerization reaction time is 2.5-6 hours.

[0023] Preferably, the temperature of the salt-forming reaction is 170-190° C., and the time of the salt-forming reaction is 1-2.5 h.

[0024] Preferably, the molar ratio of the phenolphthalein to the dihalogen double-end monomer is (1.01-1.15):1.

[0025] Preferably, the polar organic solvent is one or more of sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and N-methylpyrrolidone;

[0026] The initiator is an alkali metal carbonate and / or an alkali metal hydroxide;

[0027] The water-separating agent is one or more of toluene, xylene and trimethylbenzene.

[0028] The present invention provides the use of the polysulfone resin described in the above technical solution or the polysulfone resin prepared by the preparation method described in the above technical solution in a composite reverse osmosis membrane.

[0029] The present invention provides a composite reverse osmosis membrane, comprising a polysulfone resin-based membrane and a polyurethane membrane arranged on the surface of the polysulfone resin-based membrane;

[0030] The polysulfone resin-based membrane is prepared from the polysulfone resin described in the above technical solution or prepared by the preparation method described in the above technical solution.

[0031] The present invention provides a polysulfone resin having a structure shown in Formula I:

[0032] The n is 50 to 220; the R1 is The R2 is R3 is -NH2 or -SO3 - Na + The polysulfone resin main chain structure provided by the present invention contains both a flexible chain structure (R1 group) and a rigid chain structure (R2 group), which is helpful to improve the strength and toughness of the polysulfone resin by changing the overall chain segment of the polymer. At the same time, by introducing an active functional group (R3 group), the end of the overall chain segment of the polysulfone resin is further modified, and an -NH2 group or -SO3 - Na + The highly active terminal functional groups can significantly improve the permeability of polysulfone resins. Moreover, the highly active terminal functional groups also significantly improve the surface activity of polysulfone resins, and the binding ability with molecules of materials such as polyimide and polyurethane is enhanced through hydrogen bonds or ionic bonds, thereby enhancing the integrity of the reverse osmosis membrane and avoiding the leakage problem caused by separation between layers. The results of the examples show that the polysulfone resin provided by the present invention as the base membrane has significantly improved permeability to water molecules, and the permeation flux can reach 32.7L / (m 2 ·h·bar), the bonding strength between polysulfone resin-based film and polyurethane film is level 2-3, and there is no obvious scratch with 2H pencil hardness. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is an electron microscope photograph of the surface of the polysulfone resin-based membrane prepared in Example 5 of the present invention;

[0034] Figure 2 This is an electron microscope photograph of a cross section of a polysulfone resin-based membrane prepared in Example 5 of the present invention;

[0035] Figure 3 This is an electron microscope photograph of water molecules contacting the surface of the polysulfone resin-based membrane prepared in Example 5 of the present invention;

[0036] Figure 4 This is an electron microscope photograph of the surface of the polysulfone resin-based membrane prepared in Comparative Example 2 of the present invention;

[0037] Figure 5 This is an electron microscope photograph of water molecules contacting the surface of the polysulfone resin-based membrane prepared in Comparative Example 2 of the present invention;

[0038] Figure 6 This is a comparison diagram of water molecule contact on the surface of the polysulfone resin-based membrane prepared in Example 5 and Comparative Example 2;

[0039] Figure 7 The graph of the change of the polysulfone resin water-based membrane flux over time prepared in Example 5 and Comparative Example 2;

[0040] Figure 8 This is a graph showing how the water flux and organic dye rejection rate of the composite reverse osmosis membrane prepared in Example 5 change over time. DETAILED DESCRIPTION

[0041] The present invention provides a polysulfone resin having a structure shown in Formula I:

[0042]

[0043] The n is 50 to 220;

[0044] The R1 is

[0045] The R2 is

[0046] R3 is -NH2 or -SO3 - Na + .

[0047] The present invention provides a polysulfone resin having a structure as described in Formula I. In the present invention, the degree of polymerization n of the polysulfone resin is 50 to 220, preferably 70 to 180, and more preferably 100 to 150; in the main chain structure of the polysulfone resin provided by the present invention, R1 is The R2 is The R1 is a flexible chain structure, and the R2 is a rigid chain structure. The polysulfone resin is adjusted by the flexible chain structure and the rigid chain structure, thereby effectively improving the strength and toughness of the polysulfone resin, and further improving the processing performance of the polysulfone resin.

[0048] The polysulfone resin terminal structure R3 provided by the present invention is -NH2 or -SO3 - Na + , the substitution position of R3 is ortho, meta or para, more preferably para. The polysulfone resin provided by the present invention has R3 as the terminal structure, and R3 as a highly active functional group can significantly improve the permeability of the polysulfone resin. At the same time, the highly active terminal functional group R3 also significantly improves the surface activity of the polysulfone resin, and the intermolecular force with materials such as polyimide and polyurethane is stronger and tighter, and the binding ability is enhanced.

[0049] In a specific embodiment of the present invention, the polysulfone resin provided by the present invention preferably has a structure shown in any one of Formula I-1, Formula I-2, Formula I-3 and Formula I-4:

[0050]

[0051]

[0052] The present invention provides a method for preparing the polysulfone resin described in the above technical solution, comprising the following steps:

[0053] In a protective atmosphere, phenolphthalein, a dihalogen double-end monomer, a polar organic solvent, an initiator and a water-separating agent are mixed to perform a salt-forming reaction to obtain a salt-forming reaction liquid;

[0054] The salt-forming reaction solution and the end-capping agent are mixed to carry out polymerization reaction to obtain a polysulfone resin;

[0055] The dihalogen double-end monomer is 4,4'-dihalogenated diphenyl sulfone or 4,4'-dihalogenated dibenzophenone;

[0056] The end-capping agent is aminophenol or hydroxybenzene sulfonate.

[0057] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known to those skilled in the art.

[0058] In the present invention, phenolphthalein, a dihalogen double-end monomer, a polar organic solvent, an initiator and a water-separating agent are mixed in a protective atmosphere to carry out a salt-forming reaction to obtain a salt-forming reaction liquid.

[0059] In the present invention, the dihalogen double-end monomer is 4,4'-dihalogenated diphenyl sulfone or 4,4'-dihalogenated benzophenone, the 4,4'-dihalogenated diphenyl sulfone is preferably 4,4'-dichlorodiphenyl sulfone; the 4,4'-dihalogenated benzophenone is preferably 4,4'-difluorobenzophenone.

[0060] In the present invention, the molar ratio of the phenolphthalein to the dihalogenated double-end monomer is preferably (1.01-1.15):1, and more preferably (1.01-1):1.

[0061] In the present invention, the polar organic solvent is preferably one or more of sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and N-methylpyrrolidone, more preferably sulfolane or dimethyl sulfoxide.

[0062] In the present invention, the initiator is preferably an alkali metal carbonate and / or an alkali metal hydroxide, the alkali metal carbonate is preferably sodium carbonate and / or potassium carbonate, the alkali metal hydroxide is preferably sodium hydroxide and / or potassium hydroxide. In a specific embodiment of the present invention, the initiator is sodium carbonate.

[0063] In the present invention, the molar ratio of the initiator to the dihalogenated double-end monomer is preferably (1-1.2):1, and more preferably (1.05-1.1):1.

[0064] In the present invention, the water-separating agent is preferably one or more of toluene, xylene and trimethylbenzene, more preferably toluene.

[0065] In the present invention, the mass ratio of the initiator to the polar organic solvent is preferably (0.1-0.15):1.

[0066] In the present invention, the mixing preferably comprises the following steps:

[0067] Premixing phenolphthalein, dihalogen dual-end monomer and polar organic solvent to obtain a premixed solution;

[0068] The premixed liquid, initiator and water-separating agent are finally mixed.

[0069] The present invention premixes phenolphthalein, dihalogen dual-end monomer and polar organic solvent to obtain a premixed liquid; in the present invention, the premixing temperature is preferably 70-90°C, more preferably 80°C; the present invention controls the premixing temperature within the above range to ensure that phenolphthalein and dihalogen dual-end monomer can be dissolved in the polar organic solvent. The present invention has no special requirements for the premixing time, so that phenolphthalein and dihalogen dual-end monomer are completely dissolved in the polar organic solvent. In the present invention, the premixing is preferably to add dihalogen dual-end monomer and phenolphthalein to the polar organic solvent in sequence. In the present invention, the premixing is carried out under stirring conditions, and the present invention has no special requirements for the specific implementation process of the stirring.

[0070] In the present invention, the mass concentration of the premix is ​​preferably 20 to 35%, more preferably 25 to 30%.

[0071] After obtaining the premixed liquid, the present invention performs final mixing of the premixed liquid, the initiator and the water-separating agent. In the present invention, the final mixing is preferably to add the initiator and the water-separating agent to the premixed liquid in sequence. In the present invention, the temperature of the final mixing is preferably the same as the temperature of the premixing, and the present invention has no special requirements for the specific implementation process of the final mixing.

[0072] In the present invention, the temperature of the salt-forming reaction is preferably 170-190°C, more preferably 180°C; the time of the salt-forming reaction is 1-2.5h, more preferably within 1.5h; in the present invention, the salt-forming reaction is carried out in a protective atmosphere, and the protective atmosphere is preferably a nitrogen atmosphere or an inert gas atmosphere, more preferably a nitrogen atmosphere.

[0073] In the present invention, the salt-forming reaction is preferably carried out under stirring conditions, and the present invention has no special requirements for the specific implementation process of the stirring.

[0074] In a specific embodiment of the present invention, the salt-forming reaction is carried out in a reaction kettle equipped with a vent pipe, a condensation water separator, a stirrer and a viscometer.

[0075] In a specific embodiment of the present invention, as the salt-forming reaction proceeds in the reactor, the product water in the salt-forming reaction system azeotropes with the water separator, and condensed water is generated in the condensation water separator. As the salt-forming reaction proceeds, the water content in the azeotropic system gradually decreases. When no water is produced in the condensation water separator, the present invention determines that the salt-forming reaction is complete and obtains a salt-forming reaction liquid.

[0076] In the present invention, the salt-forming products generated in the salt-forming reaction solution include formula II, formula III and CO2;

[0077]

[0078] After obtaining the salt-forming reaction solution, the present invention mixes the salt-forming reaction solution and a capping agent to carry out a polymerization reaction to obtain a polysulfone resin.

[0079] In the present invention, the end-capping agent is aminophenol or hydroxybenzene sulfonate, and the hydroxybenzene sulfonate is preferably sodium hydroxybenzene sulfonate.

[0080] In the present invention, the hydroxybenzene sulfonate is preferably prepared by the following method:

[0081] In a protective atmosphere, aminophenol, weak base sulfuric acid salt and polar organic solvent are mixed to undergo sulfonation reaction to obtain hydroxybenzene sulfonate.

[0082] In the present invention, the weak base sulfate salt is preferably copper sulfate; in the present invention, an excess of the weak base sulfate salt is preferably added to ensure complete sulfonation of aminophenol.

[0083] In the present invention, the types of polar organic solvents used in the sulfonation reaction are the same as the types of organic solvents used in the salt-forming reaction, and are not described in detail herein.

[0084] In the present invention, the pH value of the sulfonation reaction is preferably 5-6, and the pH value of the sulfonation reaction is preferably adjusted by a strong acid, and the strong acid is preferably dilute sulfuric acid. The present invention has no special requirements on the mass concentration of the dilute sulfuric acid; the temperature of the sulfonation reaction is preferably 80-150°C, and more preferably 90°C; the time of the sulfonation reaction is preferably 2-4h, and more preferably 3h; in the present invention, the sulfonation reaction is preferably carried out in a protective atmosphere, and the protection range of the protective atmosphere is the same as the protection range of the protective atmosphere of the above-mentioned salt-forming reaction, which will not be repeated here.

[0085] After the sulfonation reaction is completed, a sulfonation reaction liquid is obtained. The present invention preferably performs post-treatment on the sulfonation reaction liquid to obtain the hydroxybenzene sulfonate. In the present invention, the post-treatment preferably includes the following steps: adjusting the pH value, solid-liquid separation, washing and drying; the present invention preferably adjusts the pH value of the sulfonation reaction liquid to 7-7.5, and the pH value is preferably adjusted by sodium carbonate solution. The present invention has no special requirements for the mass concentration of the sodium carbonate solution; the present invention preferably removes excess weak base sulfate salt by solid-liquid separation; the present invention preferably washes the solid obtained by solid-liquid separation, and the washing is preferably water washing. The present invention has no special requirements for the specific implementation process of the water washing, and the washing liquid after washing can be neutral; the present invention has no special requirements for the specific implementation process of the drying, and the moisture on the surface of the solid product can be completely dried.

[0086] In the present invention, the molar ratio of the end-capping agent to the dihalogenated double-end monomer is (0.5-5):100, more preferably (1-3):100, and most preferably (2-2.5):100.

[0087] In the present invention, the capping agent is preferably mixed in the form of a capping agent solution. In the present invention, the type of solvent used in the capping agent solution is preferably the same as the type of polar organic solvent used in the salt-forming reaction, which will not be repeated here.

[0088] In the present invention, the mass concentration of the blocking agent solution is preferably 20-30%.

[0089] In the present invention, the polymerization reaction temperature is preferably 210-230°C, and the polymerization reaction time is preferably 2.5-6h, more preferably 3.5-4h. In the present invention, the polymerization reaction is preferably carried out in a protective atmosphere, and the protection range of the protective atmosphere is the same as the protection range of the protective atmosphere of the above-mentioned salt-forming reaction, which will not be repeated here.

[0090] In the present invention, the reactor of the polymerization reaction is preferably the same as the reactor of the salt-forming reaction. The viscosity of the polymerization reaction system is monitored by a viscometer on the reactor. When the viscosity of the polymerization reaction system reaches the target degree of polymerization, the polymerization reaction is terminated.

[0091] In the present invention, when the viscosity of the polymerization reaction system reaches 7500-8500 Pa·s by monitoring the viscosity of the polymerization reaction system by a viscometer, the polymerization reaction viscous liquid is transferred to water to terminate the polymerization reaction; the water is preferably deionized water.

[0092] After the polymerization reaction is completed, a polymerization reaction liquid is obtained. The present invention preferably performs post-treatment on the polymerization reaction liquid to obtain the polysulfone resin. In the present invention, the post-treatment preferably includes: solid-liquid separation, washing and drying in sequence. The present invention has no special requirements for the specific implementation process of the solid-liquid separation. The present invention preferably washes the solid product of the solid-liquid separation. In the present invention, the washing is preferably water washing. In the present invention, the water washing preferably puts the solid product into water and boils it for washing until the conductivity of the detergent after washing is less than 5us / cm; in the present invention, the drying is preferably vacuum drying. The present invention has no special requirements for the specific implementation process of the vacuum drying; the degree of vacuum drying is preferably: drying until the moisture content of the epoxy resin toughening agent is less than 0.5wt%.

[0093] The present invention provides the use of the polysulfone resin described in the above technical solution or the polysulfone resin prepared by the preparation method described in the above technical solution in a composite reverse osmosis membrane.

[0094] In the present invention, the polysulfone resin is preferably used as a base membrane of a composite reverse osmosis membrane.

[0095] The present invention provides a composite reverse osmosis membrane, comprising a polysulfone resin-based membrane and a polyurethane membrane arranged on the surface of the polysulfone resin;

[0096] The polysulfone resin-based membrane is prepared from the polysulfone resin described in the above technical solution or prepared by the preparation method described in the above technical solution.

[0097] In the present invention, the polysulfone resin-based membrane is preferably prepared by a deposition-phase transfer method. In a specific embodiment of the present invention, the polysulfone resin is preferably prepared by the following method:

[0098] The polysulfone resin, the membrane-forming polar organic solvent and the pore-forming agent are mixed to obtain a membrane casting solution;

[0099] The casting solution is coated on the surface of the substrate and then immersed in water to perform phase transformation to form a membrane, thereby obtaining the polysulfone resin-based membrane.

[0100] In the present invention, the type of the film-forming polar organic solvent is preferably the same as the type of the polar organic solvent used in the salt-forming reaction, which will not be described in detail herein.

[0101] In the present invention, the pore former is preferably polyethylene glycol, and the mass ratio of the polyethylene glycol to the polysulfone resin is preferably 0.5:1.

[0102] In the present invention, the mass concentration of the polysulfone resin in the casting solution is preferably 5-10%.

[0103] In the present invention, the mixing temperature is preferably 80-85° C., the mixing time is preferably 6-7 hours, and the mixing is performed under stirring conditions. The present invention has no special requirements for the specific implementation process of the stirring.

[0104] After obtaining the casting solution, the present invention preferably allows the casting solution to stand for degassing before coating. In the present invention, the standing for degassing time is preferably 24 to 25 hours.

[0105] After obtaining the casting solution, the present invention applies the casting solution on a substrate and then immerses the substrate in water to perform phase transformation to form a membrane, thereby obtaining the polysulfone resin-based membrane.

[0106] In the present invention, the substrate is preferably a glass substrate. The present invention has no special requirements for the specific implementation of the coating, and the present invention has no special requirements for the thickness of the coating, which can be selected according to actual needs.

[0107] In the present invention, the water is preferably deionized water, and the immersion time is preferably 24 to 30 hours.

[0108] In the present invention, the polysulfone resin-based membrane is preferably stored in pure water.

[0109] The present invention has no special requirements on the source of the polyurethane film, and commercially available products can be used.

[0110] In the present invention, the composite reverse osmosis membrane is preferably prepared by the following method:

[0111] The polysulfone resin-based membrane and the polyurethane membrane are hot-melt composited to obtain the composite reverse osmosis membrane.

[0112] The present invention has no special requirements on the specific implementation process of the hot-melt compounding.

[0113] In the present invention, the polysulfone resin-based membrane is further modified by introducing an active functional group (R3 group) to modify the end of the polysulfone resin chain segment, and introducing an -NH2 group or -SO3 - Na + The highly active terminal functional groups significantly improve the surface activity of the polysulfone resin, make the intermolecular forces with the polyurethane membrane stronger and tighter, enhance the binding ability, enhance the integrity of the reverse osmosis membrane, and avoid leakage problems caused by separation between layers.

[0114] The technical solutions in the present invention will be described clearly and completely below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0115] Example 1

[0116] 110 kg of sulfolane was added to a 200 L stainless steel reactor equipped with a nitrogen pipe, a condensation water separator, a high-efficiency stirrer and a viscometer for monitoring the polymerized mucus in the reactor. The mixture was stirred and heated to 80°C. 17.85 kg of 4,4'-dichlorodiphenyl sulfone and 20.7 kg of phenolphthalein were added in sequence. After all the monomers were dissolved, 10 kg of sodium carbonate was added to the system in sequence for vacuum protection. After nitrogen replacement, 10 L of toluene was added to the closed system under nitrogen protection. The mixture was continuously stirred and heated to 180°C for salt-forming reaction. The water in the system was azeotropic with the water separator. Cooling water began to drip from the condenser and was separated into layers in the water separator. As the reaction continued, the amount of water in the azeotropic system became less and less. When the water discharge in the condenser was not obvious, the salt-forming stage was completed, which lasted for 1.5 hours. After the salt-forming reaction is completed, the temperature is raised to 220°C, 0.175 kg of p-aminophenol is dissolved after nitrogen replacement protection, and then placed in the reaction system under nitrogen protection and kept at a constant temperature for 2.5 hours to terminate the polymerization reaction. The product system is cooled, boiled and washed with water 10 times until the conductivity in the water is below 5 us / cm, filtered, and vacuum dried until the water weight content is less than 0.5%, to obtain a polysulfone resin.

[0117] The structure of the polysulfone resin prepared in Example 1 is as follows:

[0118]

[0119] n is 100 to 150, and the viscosity of the polymer is 7500 to 8500 Pa·s.

[0120] Example 2

[0121] 110 kg of sulfolane was added to a 200 L stainless steel reactor equipped with a nitrogen pipe, a condensation water separator, a high-efficiency stirrer and a viscometer for monitoring the polymerized mucus in the reactor. The temperature was raised to 80°C with stirring, and 14 kg of 4,4'-difluorobenzophenone and 20.7 kg of phenolphthalein were added in sequence. After all the monomers were dissolved, 10 kg of sodium carbonate was added to the system in sequence for vacuum protection. After nitrogen replacement, 10 L of toluene was added to the closed system under nitrogen protection, and stirring was continued. The temperature was raised to 180°C, and a salt-forming reaction occurred. The water in the system azeotroped with the water separator, and cooling water began to drip from the condenser and stratified in the water separator. As the reaction continued, the amount of water in the azeotropic system became less and less. When the water output in the condenser was not obvious, the salt-forming stage was completed, which lasted for 1.5 hours. After the salt-forming reaction is completed, the temperature is raised to 220°C, 0.175 kg of p-aminophenol is dissolved after nitrogen replacement protection, and then placed in the reaction system under nitrogen protection and kept at a constant temperature for 2.5 hours to terminate the polymerization reaction. The product system is cooled, boiled and washed with water 10 times until the conductivity in the water is below 5 us / cm, filtered, and vacuum dried until the water weight content is less than 0.5%, to obtain a polysulfone resin.

[0122] The structure of the polysulfone resin prepared in Example 2 is as follows:

[0123]

[0124] n is 100 to 150, and the viscosity of the polymer is 7500 to 8500 Pa·s.

[0125] Example 3

[0126] Sulfonation reaction is carried out on p-aminophenol, copper sulfate and cyclopentane sulfone in a 10L reactor equipped with a nitrogen tube, a condensation water separator and a high-efficiency agitator. The pH value of the reaction system is adjusted to 5 by dilute sulfuric acid, and the reactor is heated to 80°C and reacted for 2 hours. After -NH2 is sulfonated, the pH value of the reaction system is adjusted to 7.5 by sodium carbonate. After filtering the reaction liquid, the filter cake is washed and dried to obtain sodium hydroxybenzenesulfonate.

[0127] 110 kg of sulfolane was added to a 200 L stainless steel reactor equipped with a nitrogen pipe, a condensation water separator, a high-efficiency stirrer and a viscometer for monitoring the polymerized mucus in the reactor. The mixture was stirred and heated to 80°C. 17.85 kg of 4,4'-dichlorodiphenyl sulfone and 20.7 kg of phenolphthalein were added in sequence. After all the monomers were dissolved, 10 kg of sodium carbonate was added to the system in sequence for vacuum protection. After nitrogen replacement, 10 L of toluene was added to the closed system under nitrogen protection. The mixture was continuously stirred and heated to 180°C for salt-forming reaction. The water in the system was azeotropic with the water separator. Cooling water began to drip from the condenser and was separated into layers in the water separator. As the reaction continued, the amount of water in the azeotropic system became less and less. When the water discharge in the condenser was not obvious, the salt-forming stage was completed, which lasted for 1.5 hours. After the salt-forming reaction is completed, the temperature is raised to 220°C, 0.200 kg of sodium hydroxybenzenesulfonate is dissolved after nitrogen replacement protection, and then placed in the reaction system under nitrogen protection and kept at a constant temperature for 2.5 hours to terminate the polymerization reaction. The product system is cooled, boiled and washed 10 times until the conductivity in the water is below 5 us / cm, filtered, and vacuum dried until the water weight content is less than 0.5% to obtain a polysulfone resin.

[0128] The structure of the polysulfone resin prepared in Example 3 is as follows:

[0129]

[0130] n is 100 to 150, and the viscosity of the polymer is 7500 to 8500 Pa·s.

[0131] Example 4

[0132] The preparation method of sodium hydroxybenzene sulfonate is the same as that in Example 3.

[0133] 110 kg of sulfolane was added to a 200-liter stainless steel reactor equipped with a nitrogen pipe, a condensation water separator, a high-efficiency stirrer and a viscometer for monitoring the polymerized mucus in the reactor. The mixture was stirred and heated to 80°C. 14 kg of 4,4'-difluorobenzophenone and 20.7 kg of phenolphthalein were added in sequence. After all the monomers were dissolved, 10 kg of sodium carbonate was added to the system in sequence for vacuum protection. After nitrogen replacement, 10 L of toluene was added to the closed system under nitrogen protection. The mixture was continuously stirred and heated to 180°C for salt-forming reaction. The water in the system was azeotropic with the water separator. Cooling water began to drip from the condenser and was separated into layers in the water separator. As the reaction continued, the amount of water in the azeotropic system became less and less. When the water discharge in the condenser was not obvious, the salt-forming stage was completed, which lasted for 1.5 hours. After the salt-forming reaction is completed, the temperature is raised to 220°C, 0.200 kg of sodium hydroxybenzenesulfonate is dissolved after nitrogen replacement protection, and then placed in the reaction system under nitrogen protection and kept at a constant temperature for 2.5 hours to terminate the polymerization reaction. The product system is cooled, boiled and washed 10 times until the conductivity in the water is below 5 us / cm, filtered, and vacuum dried until the water weight content is less than 0.5% to obtain a polysulfone resin.

[0134] The structure of the polysulfone resin prepared in Example 4 is as follows:

[0135]

[0136] n is 150 to 200, and the viscosity of the polymer is 9000 to 10000 Pa·s.

[0137] Comparative Example 1

[0138] The preparation method is basically the same as that of Example 1, except that p-aminophenol is not added.

[0139] Example 5

[0140] 20 g of the polysulfone resin prepared in Example 1, 0.1 L of cyclopentane sulfone and 80 g of polyethylene glycol were stirred and mixed at 80° C. for 6 h to obtain a casting solution, which was applied on a glass substrate with a scraper, allowed to stand for 24 hours for degassing, and then immersed in deionized water for 24 hours to obtain a polysulfone resin-based membrane;

[0141] The polysulfone resin-based membrane and the polyurethane membrane are hot-melt-compounded at 134° C. to obtain a composite reverse osmosis membrane.

[0142] Figure 1 This is an electron microscope photograph of the surface of the polysulfone resin-based membrane prepared in Example 5. Figure 2 The electron microscope photograph of the cross section of the polysulfone resin base membrane prepared in Example 5 of the present invention; Figure 1 and Figure 2 It can be concluded that the polysulfone resin-based membrane prepared in Example 5 of the present invention has a loose mesh structure inside. Figure 3This is an electron microscope photograph of water molecules contacting the surface of the polysulfone resin-based membrane prepared in Example 5 of the present invention. Figure 3 It can be concluded that when the polysulfone resin-based membrane prepared in this embodiment comes into contact with water molecules, the water molecules have strong permeability and no large water droplets are formed on the surface of the polysulfone resin-based membrane.

[0143] Comparative Example 2

[0144] The preparation method is basically the same as that of Example 5, except that the polysulfone resin prepared in Comparative Example 1 is used to prepare the polysulfone resin-based membrane.

[0145] Figure 4 This is an electron microscope photo of the surface of the polysulfone resin-based membrane prepared in Comparative Example 2. Figure 5 This is an electron microscope photograph of water molecules contacting the surface of the polysulfone resin-based membrane prepared in Comparative Example 2 of the present invention. Figure 4 and 5 It can be concluded that although the polysulfone resin-based membrane prepared in Comparative Example 2 is not significantly different from the polysulfone resin-based membrane prepared in Example 5 in appearance, when the polysulfone resin-based membrane prepared in Comparative Example 2 comes into contact with water molecules, the permeability of water molecules is significantly lower than that of the polysulfone resin-based membrane prepared in Example 5, and large particles of water droplets are formed on the surface of the polysulfone resin-based membrane. Figure 6 The contact angles of the polysulfone resin-based membranes prepared in Example 5 (left side) and Comparative Example 2 (right side) when in contact with water molecules are shown in Table 1. Figure 6 It can be clearly concluded that the polysulfone resin-based membrane prepared in Example 5 of the present invention has better affinity with water molecules and improves the permeability to water molecules.

[0146] The electron microscope photographs and water affinity of the polysulfone resin-based membranes prepared by the polysulfone resins prepared in Examples 2 to 4 are similar to those of the polysulfone resin-based membrane prepared in Example 1.

[0147] Test Example 1

[0148] At 0.1 MPa, the polysulfone resin-based membranes prepared in Example 5 and Comparative Example 2 were tested for pure water permeability. The results are as follows: Figure 7 As shown, from Figure 7 It can be more intuitively obtained that the pure water flux of the polysulfone resin-based membrane prepared in Example 5 is much higher than that of the polysulfone resin-based membrane prepared in Comparative Example 2;

[0149] The surface bonding strength of the film was tested according to the GB / T6739-2006 pencil hardness test method. There were no obvious scratches with a 2H pencil hardness.

[0150] Test Example 3

[0151] At 0.1 MPa, the composite reverse osmosis membrane prepared in Example 5 was subjected to an experiment on the permeability of a dye solution (copper sulfate solution, with a mass concentration of 200 ppm). The results are as follows: Figure 8 As shown, from Figure 8 It can be intuitively obtained that the water flux of the composite reverse osmosis membrane prepared in Example 5 is as high as 32.7 L / (m 2 ·h·bar).

[0152] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for preparing a polysulfone resin, characterized in that: The following steps are involved: In a protective atmosphere, phenolphthalein, a dihalogen double-end monomer, a polar organic solvent, an initiator and a water-separating agent are mixed to perform a salt-forming reaction to obtain a salt-forming reaction liquid; The salt-forming reaction solution and the end-capping agent are mixed to carry out polymerization reaction to obtain a polysulfone resin; The dihalogen double-end monomer is 4,4'-dihalogenated diphenyl sulfone; The end-capping agent is aminophenol or hydroxybenzene sulfonate; The molar ratio of the phenolphthalein and the dihalogen double-end monomer is (1.01-1.15):1; The polysulfone resin has a structure shown in Formula I-1 or Formula I-3: In the formula I-1 and formula I-3, n is independently 50 to 220.

2. The preparation method according to claim 1, characterized in that: The molar ratio of the end-capping agent to the dihalogenated double-end monomer is (0.5-5):

100.

3. The preparation method according to claim 1 or 2, characterized in that: The polymerization reaction temperature is 210-230° C., and the polymerization reaction time is 2.5-6 hours.

4. The preparation method according to claim 1, characterized in that: The temperature of the salt-forming reaction is 170-190° C., and the time of the salt-forming reaction is 1-2.5 hours.

5. The preparation method according to claim 1 or 4, characterized in that: The polar organic solvent is one or more of sulfolane, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide and N-methylpyrrolidone; The initiator is an alkali metal carbonate and / or an alkali metal hydroxide; The water-separating agent is one or more of toluene, xylene and trimethylbenzene.

6. Use of the polysulfone resin prepared by the preparation method according to any one of claims 1 to 5 in a composite reverse osmosis membrane.

7. A composite reverse osmosis membrane, characterized in that: It comprises a polysulfone resin base film and a polyurethane film arranged on the surface of the polysulfone resin base film; The polysulfone resin-based membrane is prepared by the polysulfone resin prepared by the preparation method according to any one of claims 1 to 5.

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