High-toughness low-yellowness polyethersulfone as well as preparation method and application thereof

Abstract

The invention discloses high-toughness low-yellowness polyethersulfone as well as a preparation method and application thereof. The impact strength of the polyethersulfone is greater than 90J / m, and the yellowness index is less than 25. The polyether sulfone provided by the invention is especially suitable for application in some high-end fields, such as the fields of water treatment membranes, hemodialysis membranes and the like.

Description

Technical Field

[0001] The invention belongs to the field of polymer material synthesis, and in particular relates to a high-toughness, low-yellowness polyethersulfone and a preparation method and application thereof. Background Art

[0002] Polyethersulfone is a high-performance thermoplastic polymer with excellent mechanical properties, electrical insulation, creep resistance, heat resistance and transparency, and is widely used in various fields, such as electronic equipment, medical equipment, aerospace, etc. However, in some high-end applications, such as water treatment membranes and hemodialysis membranes, higher requirements are placed on the performance and yellowness of polyethersulfone.

[0003] The preparation method of polyether sulfone is mainly prepared by a nucleophilic substitution reaction of bisphenol S and 4,4'-dichlorodiphenyl sulfone in the presence of an alkali metal carbonate. In the prior art, the purity and yield of polyether sulfone are usually improved by optimizing reaction conditions, such as temperature, pressure, catalyst, etc. In addition, there are also some studies that improve the performance of polyether sulfone by changing the ratio of raw materials or adding specific additives. For example, some studies have found that by adjusting the ratio of bisphenol S and 4,4'-dichlorodiphenyl sulfone, polyether sulfone resins with different molecular weights can be obtained, thereby improving its mechanical properties and thermal stability.

[0004] Although the existing technology has improved the performance of polyethersulfone to a certain extent, there are still some problems that affect the light transmittance and heat resistance of polyethersulfone. In addition, the existing polyethersulfone products may be affected in certain high-end fields such as water treatment membranes and hemodialysis membranes due to excessively high yellowness index of the solution, insufficient material toughness and poor solubility during use. Summary of the invention

[0005] The inventors of the present application unexpectedly discovered in their research that due to the limitation of the synthesis process, a small amount of 2,4 isomers, namely 2,4'-dihydroxydiphenyl sulfone and 2,4'-dichlorodiphenyl sulfone, will exist in the monomers of bisphenol S (4,4'-dihydroxydiphenyl sulfone) and 4,4'-dichlorodiphenyl sulfone. Since these isomers have greater steric hindrance during polymerization, excessive content of isomers will reduce the polymerization reaction rate, prolong the reaction time, increase the side reactions, and further affect the product performance. On this basis, the inventors completed the present invention by adjusting the content of isomers.

[0006] Another object of the present invention is to provide a method for preparing the high-toughness, low-yellowness polyethersulfone.

[0007] Another object of the present invention is to improve the application of this high-toughness, low-yellowness polyethersulfone.

[0008] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solution:

[0009] A high-toughness, low-yellowness polyethersulfone having repeating units represented by the following formulas I and II, wherein the ratio of the molar content m of the repeating unit represented by formula I to the molar content n of the repeating unit represented by formula II, i.e., m:n, is 1:3000 to 1:500000;

[0010]

[0011] In a specific embodiment, the polyethersulfone has an impact strength greater than 90 J / m and a yellowness index less than 25;

[0012] In a preferred embodiment, the weight average molecular weight of the polyethersulfone is between 50,000 and 140,000 g / mol, preferably between 60,000 and 100,000 g / mol; and the molecular weight distribution is less than 2.0, preferably between 1.5 and 1.9.

[0013] On the other hand, the preparation method of the aforementioned high-toughness and low-yellowness polyethersulfone comprises the following steps:

[0014] 1) Salt-forming stage: Monomer 1, Monomer 2 and salt-forming agent are dissolved in a reaction solvent, and then an optional water-carrying agent is added to the reaction kettle under stirring, heated to reflux for reaction, and then the temperature is increased to completely evaporate the water-carrying agent in the reaction kettle;

[0015] 2) Polymerization stage: After the polymerization reaction, the stirring speed is reduced, and then a capping agent is added for capping. The reaction fluid is then filtered, crushed, washed with water, and vacuum dried to obtain polyether sulfone.

[0016] In a specific embodiment, the monomer one is bisphenol S (4,4'-dihydroxydiphenyl sulfone) with a purity of more than 99.9%, the monomer two is 4,4'-dichlorodiphenyl sulfone with a purity of more than 99.9%, and the sum of the contents of 2,4 isomers (2,4'-dichlorodiphenyl sulfone and 2,4'-dihydroxydiphenyl sulfone) of monomer one and monomer two is less than 300 ppm, preferably less than 200 ppm.

[0017] In a specific embodiment, the first monomer is bisphenol S (4,4'-dihydroxydiphenyl sulfone) with a purity of more than 99.9%, wherein the content of 2,4'-dihydroxydiphenyl sulfone is less than 100 ppm, preferably the content of 2,4'-dihydroxydiphenyl sulfone is less than 50 ppm; and / or

[0018] The second monomer is 4,4'-dichlorodiphenyl sulfone with a purity of more than 99.9%, wherein the content of 2,4'-dichlorodiphenyl sulfone is less than 100 ppm, and preferably the content of 2,4'-dichlorodiphenyl sulfone is less than 50 ppm.

[0019] In a specific embodiment, the reaction solvent is one or more of sulfolane, N,N-dimethylacetamide or N-methylpyrrolidone.

[0020] In a specific embodiment, the salt-forming agent is one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate.

[0021] In a specific embodiment, the water-carrying agent is one or more of toluene, xylene, o-xylene, chlorobenzene, mesitylene, or no water-carrying agent is used.

[0022] In a specific embodiment, the capping agent is methyl chloride.

[0023] In a specific embodiment, the salt formation stage is heated to 140-220° C. for reflux reaction for 2-6 hours, and the polymerization stage is reacted at 160-230° C. for 2-48 hours.

[0024] On the other hand, the aforementioned high-toughness, low-yellowness polyethersulfone or the high-toughness, low-yellowness polyethersulfone prepared by the aforementioned preparation method is used in the fields of water treatment membranes and hemodialysis membranes.

[0025] Compared with the prior art, the present invention has the following beneficial effects:

[0026] (1) The present invention effectively controls the content of 2,4 isomers in bisphenol S and 4,4'-dichlorodiphenyl sulfone to less than 100 ppm, thereby reducing the content of 2,4 isomers in the final product, thereby improving the light transmittance and heat resistance of polyether sulfone.

[0027] (2) The polyethersulfone prepared by the present invention satisfies m:n<1:3000, the impact strength of the polyethersulfone is greater than 90 J / m, and the yellowness index is less than 25. This product with low yellowness index and high toughness is more suitable for application in high-end fields, such as optical materials, medical devices and other fields. DETAILED DESCRIPTION

[0028] The preferred embodiments of the present invention will be described in more detail below. Although the preferred embodiments of the present invention are described below, it should be understood that the present invention can be implemented in various forms and should not be limited to the embodiments set forth herein.

[0029] A polyethersulfone, the general structure of which is composed of repeating units represented by formula I and formula II:

[0030]

[0031] In the polyethersulfone of the present invention, the ratio of m:n of the repeating units of formula I and formula II is between 1:3000 and 500000, for example, 1:3000, 1:5000, 1:8000, 1:10000, 1:50000, 1:80000, 1:100000, 1:300000, 1:500000, etc.

[0032] In the polyethersulfone of the present invention, reducing the ratio of m:n to a specific range will improve the toughness and solubility of the material and reduce the yellowness index.

[0033] However, due to the limitation of the synthesis process, a small amount of 2,4 isomers, namely 2,4'-dihydroxydiphenyl sulfone and 2,4'-dichlorodiphenyl sulfone, will exist in the monomers of bisphenol S (4,4'-dihydroxydiphenyl sulfone) and 4,4'-dichlorodiphenyl sulfone. Since these isomers have greater steric hindrance during polymerization, excessive content of isomers will reduce the polymerization reaction rate, prolong the reaction time, increase the side reactions, and cause the ratio of m:n to be greater than 1:3000, so that the performance of polyether sulfone deteriorates.

[0034] In the polyethersulfone of the present invention, its weight average molecular weight is between 50000 and 140000 g / mol, for example, the weight average molecular weight is 50000 g / mol, 60000 g / mol, 70000 g / mol, 80000 g / mol, 90000 g / mol, 100000 g / mol, 110000 g / mol, 120000 g / mol, 130000 g / mol, 140000 g / mol, etc., preferably between 60000 and 100000 g / mol. At the same time, the molecular weight distribution is less than 2.0, for example, 1.9, 1.8, 1.7, 1.6, 1.5, etc., preferably 1.5 to 1.9.

[0035] The preparation method of the polyether sulfone of the present invention is not particularly limited, and the salt-forming polymerization method of the prior art can be used. The key is to control the content of 2,4 isomers in the monomers bisphenol S (4,4'-dihydroxydiphenyl sulfone) and 4,4'-dichlorodiphenyl sulfone to be less than 100 ppm, preferably less than 50 ppm. The control method is also not particularly limited, for example, the refining, adsorption and other processes commonly used in the art can be used, as long as the content of 2,4 isomers in bisphenol S and 4,4'-dichlorodiphenyl sulfone is less than 100 ppm.

[0036] Specifically, the bisphenol S and 4,4'-dichlorodiphenyl sulfone raw materials can be processed by recrystallization, chromatography, adsorption, reflux extraction and the like. For example, the reflux extraction method, specifically, taking bisphenol S as an example, the purchased 99.5% or 99.8% bisphenol S is refined, and the anisole reflux extraction method can be used to remove the isomer 2,4'-dihydroxydiphenyl sulfone.

[0037] An exemplary preparation method is provided below, but does not constitute any limitation.

[0038] A method for preparing high-toughness and low-yellowness polyether sulfone comprises the following steps:

[0039] The monomer 1, the monomer 2 and the salt-forming agent are dissolved in a reaction solvent, and then a water-carrying agent is added to a reaction kettle under stirring, and the reaction is heated to reflux, and then the temperature is increased to completely evaporate the water-carrying agent in the reaction kettle to start a polymerization reaction; after the polymerization reaction, the stirring speed is reduced, and then a capping agent is added for capping, and then the reaction liquid is filtered, crushed, washed with water, and vacuum dried to obtain polyethersulfone.

[0040] In a specific embodiment, the monomer one is bisphenol S (4,4'-dihydroxydiphenyl sulfone) with a purity of more than 99.9%, and the monomer two is 4,4'-dichlorodiphenyl sulfone with a purity of more than 99.9%, and the sum of the contents of 2,4 isomers (2,4'-dichlorodiphenyl sulfone and 2,4'-dihydroxydiphenyl sulfone) of the monomer one and the monomer two is less than 300 ppm, and preferably the sum of the contents is less than 200 ppm.

[0041] In a preferred embodiment, the monomer 1 is bisphenol S, and the monomer 2 is 4,4'-dichlorodiphenyl sulfone; the monomer 1 is bisphenol S (4,4'-dihydroxydiphenyl sulfone), the purity of which is above 99.9%, wherein the content of 2,4'-dihydroxydiphenyl sulfone is less than 100ppm, for example, 98ppm, 95ppm, 90ppm, 80ppm, 70ppm, 60ppm, 50ppm, 40ppm, 30ppm, 20ppm, 10ppm, 8ppm, 5ppm, etc., preferably The content of 2,4'-dihydroxydiphenyl sulfone is selected to be <50ppm; the second monomer is 4,4'-dichlorodiphenyl sulfone with a purity of more than 99.9%, wherein the content of 2,4'-dichlorodiphenyl sulfone is <100ppm, for example 98ppm, 95ppm, 90ppm, 80ppm, 70ppm, 60ppm, 50ppm, 40ppm, 30ppm, 20ppm, 10ppm, 8ppm, 5ppm, etc., preferably the content of 2,4'-dichlorodiphenyl sulfone is <50ppm.

[0042] In a more preferred embodiment, the first monomer is bisphenol S (4,4'-dihydroxydiphenyl sulfone) with a purity of more than 99.9%, wherein the content of 2,4'-dihydroxydiphenyl sulfone is less than 100 ppm, and the second monomer is 4,4'-dichlorodiphenyl sulfone with a purity of more than 99.9%, wherein the content of 2,4'-dichlorodiphenyl sulfone is less than 100 ppm. More preferably, the content of 2,4'-dihydroxydiphenyl sulfone is less than 50 ppm, and the content of 2,4'-dichlorodiphenyl sulfone is less than 50 ppm.

[0043] The salt-forming agent is one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate, preferably sodium carbonate and / or potassium carbonate; the reaction solvent is one or more of sulfolane, N,N-dimethylacetamide, or N-methylpyrrolidone; the water-carrying agent is one or more of toluene, xylene, o-xylene, chlorobenzene, and mesitylene, or no water-carrying agent is added, preferably xylene; and the end-capping agent is methyl chloride.

[0044] In the salt-forming stage, the reaction is heated to 140-220°C and refluxed for 2-6 hours. The reflux temperature is, for example, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, etc., and can be set according to the boiling point of the reaction solvent, for example, lower than the boiling point of the reaction solvent; the reflux time is, for example, 2h, 3h, 4h, 5h, 6h, etc., based on the fact that no water is produced.

[0045] In the polymerization stage, the reaction is carried out at 160-230°C for 2-48h. For example, the polymerization reaction temperature is 160°C, 170°C, 180°C, 190°C, 200°C, 210°C, 220°C, etc., and the polymerization reaction time is 2h, 3h, 4h, 5h, 6h, 10h, 16h, 20h, 25h, 30h, 35h, 40h, 45h, 48h, etc. In the actual preparation process, the degree of polymerization reaction can also be judged by monitoring indicators such as the viscosity of the reaction system or the current value.

[0046] In the present invention, there is no particular restriction on the amount of each reaction raw material. For example, taking bisphenol S and dichlorodiphenyl sulfone as the reaction raw materials, the amount ratio of bisphenol S to dichlorodiphenyl sulfone is 1:1.0 to 1:1.03, the amount of the salt-forming agent added is 1.05 to 1.3 times the amount of the bisphenol S substance, the amount of the reaction solvent added is such that the solid content of the reaction system reaches 20% to 40%, the amount of the water-carrying agent added is 0.1 to 0.5 of the mass of the reaction solvent, and the amount of the end-capping agent added is 0.02 to 0.1 of the molar amount of the bisphenol S.

[0047] The reaction conditions of the present invention are all under nitrogen atmosphere, and the reaction container is baked, dried to remove water, and evacuated and filled with nitrogen for many times.

[0048] Any steps not specifically described in the present invention may refer to the prior art, such as reactive liquid filtration, crushing, water washing, vacuum drying and the like, which may be implemented by conventional technical means in the art.

[0049] The present invention is further explained below by more specific examples, but does not constitute any limitation.

[0050] The test methods and test conditions used in the following examples are:

[0051] The molecular weight of polyethersulfone was determined by gel permeation chromatography (GPC), with DMF containing 20 mmol lithium bromide as the mobile phase, PMMA as the standard sample, and Agilent MIXD C, MIXD D, and MIXD E columns connected in series at a flow rate of 1.0 mL / min.

[0052] Izod notched impact strength was tested according to ASTM D256;

[0053] The yellowness index is tested according to ASTM E313 (2 mm).

[0054] The raw materials used in the following examples can be purchased from the market unless otherwise specified.

[0055] Preparation Example

[0056] 1 kg of 99.8% bisphenol S purchased from the market is placed in 20 kg of anisole, heated to reflux under stirring, cooled and filtered after reflux for 1 hour to obtain a high-purity refined product with a purity of more than 99.9%. By controlling the reflux time, bisphenol S with different 2,4′-dihydroxydiphenyl sulfone contents can be obtained.

[0057] The same method as above was used to obtain 4,4'-dichlorodiphenyl sulfone with different 2,4'-dichlorodiphenyl sulfone contents by controlling the reflux time.

[0058] Example 1

[0059] Step 1: Use 99.9% pure bisphenol S (the content of 2,4 isomers is 23ppm) and 99.9% dichlorodiphenyl sulfone (the content of 2,4 isomers is 20ppm) as reaction raw materials.

[0060] Step 2: Polymerization reaction. In a 100L reactor, 12514g (50mol) of bisphenol S, 14358g (50mol) of dichlorodiphenyl sulfone, and 5829g (55mol) of sodium carbonate were added to 43089g of cyclopentane sulfone in sequence, and then 10L of xylene was added to the reactor, and the xylene was refluxed with water at 180°C. When no water was produced, the temperature was increased to completely evaporate the xylene in the reactor, and then the polymerization was carried out at 220°C for 3.5h, and the temperature was lowered to 150°C, and methyl chloride was introduced for end-capping for 30min.

[0061] Step 3: Post-treatment: After the reaction is completed, the reaction liquid is filtered, the filtrate is slowly poured into water for precipitation and crushed, the crushed sample is boiled in boiling water (100° C.), and finally dried to obtain polyethersulfone powder.

[0062] Step 4: Performance evaluation. The results show that the weight average molecular weight of the prepared polyethersulfone is 96580 g / mol, the molecular weight distribution is 1.72, m:n is 1:23200, the Izod notched impact strength is 98 J / m, and the yellowness index is 9.

[0063] Example 2

[0064] The difference from Example 1 is that N-methylpyrrolidone is used as the solvent, xylene is not added, the polymerization temperature is 200° C., and the polymerization time is 4.5 h.

[0065] Performance evaluation: The results show that the weight average molecular weight of the prepared polyethersulfone is 96215 g / mol, the molecular weight distribution is 1.70, m:n is 1:23250, the Izod notched impact strength is 99 J / m, and the yellowness index is 8.

[0066] Example 3

[0067] The difference from Example 1 is that bisphenol S with a purity of 99.8% (the content of 2,4 isomers is 48 ppm) is used as the reaction raw material.

[0068] Molecular structure characterization: The weight average molecular weight of the prepared polyethersulfone is 95872 g / mol, the molecular weight distribution is 1.72, the m:n is 1:14600, the Izod notched impact strength is 95 J / m, and the yellowness index is 14.

[0069] Example 4

[0070] The difference from Example 1 is that bisphenol S with a purity of 99.5% (the content of 2,4 isomers is 245 ppm) is used as the reaction raw material.

[0071] Performance evaluation: The weight average molecular weight of the prepared polyethersulfone is 94276 g / mol, the molecular weight distribution is 1.75, m:n is 1:3600, the Izod notched impact strength is 92 J / m, and the yellowness index is 24.

[0072] Example 5

[0073] The difference from Example 1 is that 99.5% dichlorodiphenyl sulfone (the content of 2,4 isomers is 208 ppm) is used as the reaction raw material.

[0074] Performance evaluation: The weight average molecular weight of the prepared polyethersulfone is 94584 g / mol, the molecular weight distribution is 1.74, m:n is 1:4200, the Izod notched impact strength is 93 J / m, and the yellowness index is 22.

[0075] Comparative Example 1

[0076] The difference from Example 1 is that 99.5% pure bisphenol S (the content of 2,4 isomers is 245 ppm) and 99.5% dichlorodiphenyl sulfone (the content of 2,4 isomers is 208 ppm) are used as reaction raw materials.

[0077] Performance evaluation: The weight average molecular weight of the prepared polyethersulfone is 93548 g / mol, the molecular weight distribution is 1.77, m:n is 1:2150, the Izod notched impact strength is 86 J / m, and the yellowness index is 35.

[0078] Comparative Example 2

[0079] The difference from Example 1 is that bisphenol S with a purity of 99.0% (the content of 2,4 isomers is 580 ppm) is used.

[0080] Performance evaluation: The weight average molecular weight of the prepared polyethersulfone is 92115 g / mol, the molecular weight distribution is 1.79, m:n is 1:1600, the Izod notched impact strength is 81 J / m, and the yellowness index is 48.

[0081] Comparative Example 3

[0082] The difference from Example 1 is that 99.0% pure bisphenol S (the content of 2,4 isomers is 580 ppm) and 99.0% dichlorodiphenyl sulfone (the content of 2,4 isomers is 641 ppm) are used as reaction raw materials.

[0083] Performance evaluation: The weight average molecular weight of the prepared polyethersulfone is 91025 g / mol, the molecular weight distribution is 1.81, m:n is 1:780, the Izod notched impact strength is 78 J / m, and the yellowness index is 59.

Claims

1. A high-toughness, low-yellowness polyethersulfone, characterized in that: Having repeating units represented by the following formulas Ⅰ and Ⅱ, the ratio of the molar content m of the repeating unit represented by formula Ⅰ to the molar content n of the repeating unit represented by formula Ⅱ, i.e., m:n, is 1:3000 to 1:500000, preferably 1:5000 to 1:50000; 2. The high-toughness, low-yellowness polyethersulfone according to claim 1, characterized in that: The polyethersulfone has an impact strength greater than 90 J / m and a yellowness index less than 25; Preferably, the weight average molecular weight of the polyethersulfone is between 50,000 and 140,000 g / mol, preferably between 60,000 and 100,000 g / mol; and the molecular weight distribution is less than 2.0, preferably between 1.5 and 1.

9.

3. The method for preparing the high-toughness, low-yellowness polyethersulfone according to claim 1 or 2, characterized in that: The following steps are involved: 1) Salt-forming stage: Monomer 1, Monomer 2 and salt-forming agent are dissolved in a reaction solvent, and then an optional water-carrying agent is added to the reaction kettle under stirring, heated to reflux for reaction, and then the temperature is increased to completely evaporate the water-carrying agent in the reaction kettle; 2) Polymerization stage: After the polymerization reaction, the stirring speed is reduced, and then a capping agent is added for capping. The reaction fluid is then filtered, crushed, washed with water, and vacuum dried to obtain polyether sulfone.

4. The preparation method according to claim 3, characterized in that: The monomer one is bisphenol S (4,4'-dihydroxydiphenyl sulfone) with a purity of more than 99.9%, and the monomer two is 4,4'-dichlorodiphenyl sulfone with a purity of more than 99.9%. In addition, the sum of the contents of 2,4 isomers (2,4'-dichlorodiphenyl sulfone and 2,4'-dihydroxydiphenyl sulfone) of the monomer one and the monomer two is less than 300 ppm, and preferably the sum of the contents is less than 200 ppm.

5. The method for preparing polyethersulfone according to claim 4, characterized in that: The first monomer is bisphenol S (4,4'-dihydroxydiphenyl sulfone) with a purity of more than 99.9%, wherein the content of 2,4'-dihydroxydiphenyl sulfone is less than 100 ppm, preferably the content of 2,4'-dihydroxydiphenyl sulfone is less than 50 ppm; and / or The second monomer is 4,4'-dichlorodiphenyl sulfone with a purity of more than 99.9%, wherein the content of 2,4'-dichlorodiphenyl sulfone is less than 100 ppm, and preferably the content of 2,4'-dichlorodiphenyl sulfone is less than 50 ppm.

6. The preparation method according to any one of claims 3 to 5, characterized in that: The reaction solvent is one or more of sulfolane, N,N-dimethylacetamide or N-methylpyrrolidone.

7. The preparation method according to any one of claims 3 to 5, characterized in that: The salt-forming agent is one or more of sodium hydroxide, potassium hydroxide, cesium hydroxide, potassium carbonate, sodium carbonate, cesium carbonate, potassium bicarbonate, and sodium bicarbonate.

8. The preparation method according to any one of claims 3 to 5, characterized in that: The water-carrying agent is one or more of toluene, xylene, o-xylene, chlorobenzene, mesitylene, or no water-carrying agent is used; and / or The end-capping agent is methyl chloride.

9. The preparation method according to any one of claims 3 to 5, characterized in that: The salt formation stage is heated to 140-220°C for reflux reaction for 2-6 hours, and the polymerization stage is reacted at 160-230°C for 2-48 hours.

10. Use of the high-toughness, low-yellowness polyethersulfone according to claim 1 or 2 or the high-toughness, low-yellowness polyethersulfone prepared by the preparation method according to any one of claims 3 to 9 in the fields of water treatment membranes and hemodialysis membranes.

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