Production process of polyarylene (ether) sulfone with improved performance

Abstract

The present invention relates to a production process of polyarylene (ether) sulfone having high molecular weight, excellent purity, low content of undesirable volatile substances and reduced content of cyclic oligomers, polyarylene (ether) sulfone obtained from the process of the present invention, and parts made from the polyarylene (ether) sulfone of the present invention such as membranes.

Description

Technical Field

[0001] The present invention relates to a production process of polyarylene (ether) sulfone having high molecular weight, excellent purity, low content of undesirable volatile substances and reduced content of cyclic oligomers, polyarylene (ether) sulfone obtained from the process of the present invention, and parts such as membranes made from the polyarylene (ether) sulfone of the present invention.

[0002] Polyarylene (ether) sulfone belongs to the group of high-performance polymers and provides excellent heat resistance, good mechanical properties and high flame retardancy (E.M. Koch, H.-M. Walter, Kunststoffe 80 (1990) 1146; E. Doering, Kunststoffe 80, (1990) 1149, N. Inchaurondo-Nehm, Kunststoffe 98, (2008) 190).

[0003] The production of polyarylene (ether) sulfone can be carried out by using the so-called "hydroxide method", and the phenolate is formed by the reaction of a dihydroxy monomer component with a hydroxide. Another method is the so-called "carbonate route" in which the monomer is dissolved in a solvent and then potassium carbonate is added. General information on both synthetic methods can be found in the literature (for example, R.N. Johnson et.al., J. Polym. Sci. A-1 5 (1967) 2375, J.E. McGrath et.al., Polymer 25 (1984) 1827).

[0004] Processes for preparing polyarylene (ether) sulfones based on aromatic bishalogen compounds and aromatic bisphenols or their salts in the presence of at least one alkali metal carbonate or bicarbonate, ammonium carbonate or ammonium bicarbonate in an aprotic solvent are well known (see, for example, US4870153, EP113112, EP-A297363 and EP-A135130, WO2019 / 002226, WO2013 / 020871 and WO2014 / 177638). Among them, it is possible to find suitable reaction conditions such as particularly suitable monomers, catalysts and solvents, suitable ratios of components, temperature, pressure, mixing conditions and post-treatment conditions.

[0005] As is known from the literature (see, for example, Savariar et.al., Desalination 144(2002)15-20), polyarylene (ether) sulfones contain a significant amount of unwanted cyclic oligomers. Among these, in particular, cyclic dimers tend to crystallize from the solution and cause problems, for example, during the processing of polyarylene (ether) sulfone solutions in membrane production processes. Since most microfiltration and ultrafiltration membranes are prepared by a phase inversion process from a solution, a product with a reduced content of cyclic oligomers such as cyclic dimers is required. An improved process is needed that provides a product with a low cyclic dimer content without the need to remove cyclic dimers in subsequent purification steps. As is known from the literature, products with a cyclic dimer content of about 1.2 wt% are commercially available. However, especially for membrane production, the lower the content of cyclic oligomers and dimers, the better. In particular, a process that provides high molecular weight polymers and at the same time a level of cyclic dimers below 1.2 wt% is highly desirable. Furthermore, a common problem with commercially available polyarylene (ether) sulfones is that the amount of unwanted aromatic volatile substances such as toluene and / or chlorobenzene is too high. Volatile substances can migrate from membranes made from materials containing aromatic volatile substances, which is undesirable and obstructive for most membrane applications.

[0006] The object of the present invention was to provide a production process for high molecular weight polyarylene (ether) sulfone containing very low contents of cyclic oligomers (especially cyclic dimers). It was also an object to provide polyarylene (ether) sulfone containing small amounts of aromatic volatile substances such as toluene and / or chlorobenzene and showing high purity. In particular, the polyarylene (ether) sulfone polymer is suitable for use in membranes.

[0007] This problem was solved by a process for preparing a polyarylene (ether) sulfone polymer (P) comprising the following steps. I) At an initial temperature T 1 providing a reaction mixture R M wherein the reaction mixture comprises A) at least one aromatic dihalogen sulfone; B) at least one dihydroxy component; C) at least one carbonate component in an amount at least 3 mol% in excess relative to the dihydroxy component B); D) at least one aprotic solvent; and the initial concentration of each of the monomers A) and B) in the reaction mixture R M is 2.2 to 2.7 mol per liter of the at least one aprotic solvent D); and II) heating the reaction mixture R M from the initial temperature T 1 to a final reaction temperature T F at a rate of at least 0.4 K / min to obtain a product mixture (P M ).

[0008] Surprisingly, the process of the present invention has been found to yield high molecular weight poly(arylene)(ether)sulfone polymers having a particularly low content of cyclic dimers, high purity, particularly low turbidity, and desirably low contents of aromatic volatile substances such as chlorobenzene. The process of the present invention results in polymers having a low content of cyclic oligomers and low contents of undesirable particles and volatile substances that cause turbidity, obviating the need for a separate purification step to remove such substances from the polymer product. Furthermore, the polymers obtained by the process of the present invention have been found to be particularly suitable for the production of membranes in solution processes, since they do not cause clogging of the filter during the processing of polymer solutions prepared using these polymers.

[0009] According to the process of the present invention, in step I), a reaction mixture R containing constituents A), B), C and D) M is provided. Herein, each of constituents A) and B) may be referred to as a "monomer", or together they may be referred to as "monomers". Constituent C) acts as a base to deprotonate constituent B), and constituent D) acts as a solvent during the polycondensation reaction. The reaction mixture R M is provided at an initial temperature T 1 .

[0010] The reaction mixture R M is the mixture provided at the start of the reaction, i.e., before the actual process occurs, i.e., during the polycondensation between monomer A) and monomer B). During the process of the present invention, the reaction mixture R M is converted to a product mixture P M under the reaction conditions of the present invention, and the reaction mixture R M is heated to a specific final reaction temperature T F at which the polycondensation reaction mainly occurs. The polycondensation reaction yields the desired poly(arylene)(ether)sulfone polymer (P) product. The mixture obtained after the polycondensation is carried out is the product mixture P MIt is also called. The product mixture contains the desired polyarylene(ether)sulfone polymer (P), but usually also contains the halide compounds formed during the conversion of component D) and the reaction mixture R M During the conversion of the reaction mixture, component C) deprotonates component B), and the deprotonated component B) reacts with component A) to form a halide.

[0011] The process of the present invention is carried out according to the so-called "carbonate method" and not according to the so-called "hydroxide method" involving the isolation of phenolate anions. In one embodiment, the reaction mixture (R M ) essentially does not contain sodium hydroxide and potassium hydroxide. More preferably, according to this embodiment, the reaction mixture (R M ) essentially does not contain alkali metal hydroxides and alkaline earth metal hydroxides. The term "essentially does not contain" in this case is understood to mean that the reaction mixture (R M ) contains less than 100 ppm, preferably less than 50 ppm, of sodium hydroxide and potassium hydroxide, preferably alkali metal hydroxides and alkaline earth metal hydroxides, based on the total weight of the reaction mixture (R M ). It is even more preferable that the reaction mixture (R M ) does not contain toluene. It is particularly preferable that the reaction mixture (R M ) does not contain any substance that forms an azeotrope with water.

[0012] As used herein, "at least one" generally may mean one or two or more, such as three or four or five or more, and "more" may mean plural or innumerable. For example, it may mean one, or two or more mixtures. When used in relation to chemical compounds, "at least one" is indicated in the sense of describing one or two or more chemical compounds having different chemical compositions, i.e., chemical properties.

[0013] According to step I) of the process of the present invention, the reaction mixture R M contains at least one aromatic dihalosulfone as component A).

[0014] At least one aromatic dihalosulfone A) is preferably at least one dihalodiphenylsulfone. Thus, the present invention also relates to a method in which the reaction mixture (R M ) contains at least one dihalodiphenylsulfone as component A). The reaction mixture R M preferably contains, as component A), at least 50% by weight of dihalodiphenylsulfone based on the total weight of component A) in the reaction mixture R M . Preferred dihalodiphenylsulfones are selected from 4,4'-dihalodiphenylsulfones. Particularly preferably, at least one component A) is selected from 4,4'-dichlorodiphenylsulfone, 4,4'-difluorodiphenylsulfone and 4,4'-dibromodiphenylsulfone.

[0015] According to one embodiment, at least one aromatic dihalosulfone of component A) is 4,4'-dichlorodiphenylsulfone.

[0016] According to a further embodiment, at least one aromatic dihalosulfone of component A) is 4,4'-difluorodiphenylsulfone.

[0017] Thus, the present invention also relates to a method in which component A) contains at least one aromatic dihalosulfone selected from the group consisting of at least 50% by weight of 4,4'-dichlorodiphenylsulfone and 4,4'-difluorodiphenylsulfone based on the total weight of component A) in the reaction mixture (R M ).

[0018] In a particularly preferred embodiment, component A) is the reaction mixture (R MBased on the total weight of component A) therein, it contains at least 80% by weight, preferably at least 90% by weight, more preferably at least 98% by weight of an aromatic dihalogen sulfone selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone. In an even more preferred embodiment, component A) consists essentially of at least one aromatic dihalogen sulfone selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone. In this case, "consisting essentially of" means that component A) in each case is the reaction mixture R M contains more than 99% by weight, preferably more than 99.5% by weight, particularly preferably more than 99.9% by weight, of at least one aromatic dihalogen sulfone compound selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone, based on the total weight of component A) in the reaction mixture R. In the above embodiment, 4,4'-dichlorodiphenyl sulfone is particularly preferred as component A).

[0019] In an even more preferred embodiment, component A) consists of 4,4'-dichlorodiphenyl sulfone.

[0020] The reaction mixture R M contains at least one dihydroxy component B). The dihydroxy component used is typically a component having two phenolic hydroxyl groups. Since the reaction mixture R M contains at least one carbonate component, the hydroxyl groups of component B) in the reaction mixture R M can be present in a partially deprotonated form.

[0021] Component B) can be selected from the following compounds: -dihydroxybenzene, especially hydroquinone and resorcinol; -Dihydroxynaphthalenes, especially 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene; -Dihydroxybiphenyls, especially 4,4'-biphenol and 2,2'-biphenol; -Biphenyl ethers, especially bis(4-hydroxyphenyl) ether and bis(2-hydroxyphenyl) ether; -Biphenylpropanes, especially 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane and 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane; -Biphenylmethanes, especially bis(4-hydroxyphenyl)methane; -Biphenyl sulfones, especially bis(4-hydroxyphenyl) sulfone; -Biphenyl sulfides, especially bis(4-hydroxyphenyl) sulfide; -Biphenyl ketones, especially bis(4-hydroxyphenyl) ketone; -Biphenyl hexafluoropropanes, especially 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)hexafluoropropane; and -Biphenyl fluorene, especially 9,9-bis(4-hydroxyphenyl)fluorene.

[0022] Particularly preferably, the monomer component B) is selected from dihydroxybiphenyls such as 4,4'-biphenol, biphenylpropanes such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) and biphenyl sulfones such as bis(4-hydroxyphenyl) sulfone.

[0023] According to a further preferred embodiment, the monomer component B) may also be selected from the group consisting of hydroquinone, resorcinol, dihydroxynaphthalenes, especially 2,7-dihydroxynaphthalene, bisphenol A, dihydroxydiphenyl sulfone and 4,4'-biphenol.

[0024] According to a further embodiment, it is possible to use a trifunctional compound as component B). In this case, a branched structure results. When a trifunctional component B) is used, 1,1,1-tris(4-hydroxyphenyl)ethane is preferred.

[0025] The ratio of component A) to component B) is in principle derived from the stoichiometry of the polycondensation reaction proceeding with the theoretical removal of hydrogen chloride and is established by methods known to those skilled in the art. In order to control the end groups in the resulting final product, the ratio of component B) to component A) can be adjusted accordingly. More particularly, the molar ratio of component B) to component A) is from 0.98 to 1.08, in particular from 0.99 to 1.06, most preferably from 1.000 to 1.05. The molar ratio of B) to A) may also be 1:1.

[0026] According to the invention, the reaction mixture R M the initial concentrations of each monomer A) and B) therein are important and have been found to have to be from 2.2 to 2.7 mol, in particular from 2.2 to 2.67, more specifically from 2.2 to 2.65, even more specifically from 2.2 to 2.6 per liter of at least one aprotic solvent component D). According to a further embodiment, R M the monomer concentration therein may preferably be from 2.2 to 2.55, more particularly from 2.2 to 2.5, even more particularly from 2.2 to 2.45 mol per liter of at least one aprotic solvent component D). The preferred ranges apply independently to each of monomers A) and B).

[0027] According to the process of the invention, the reaction mixture R M contains, as component C), at least one carbonate component in an excess of at least 3 mol% relative to the dihydroxy component B).

[0028] "At least one carbonate component" is understood to mean exactly one carbonate component as well as a mixture of two or more carbonate components. The at least one carbonate component is preferably at least one metal carbonate. The metal carbonate is preferably anhydrous. Alkali metal carbonates and / or alkaline earth metal carbonates as the metal carbonate are preferred. As the metal carbonate, at least one metal carbonate selected from the group consisting of sodium carbonate, potassium carbonate and calcium carbonate is particularly preferred. Potassium carbonate is most preferred. For example, component C) is the reaction mixture R M contains at least 50% by weight, more preferably at least 70% by weight, most preferably at least 90% by weight of potassium carbonate, based on the total weight of the at least one carbonate component in. Therefore, a further embodiment of the present invention is a process in which component C) contains at least 50% by weight of potassium carbonate, based on the total weight of component C). In a preferred embodiment, component C) consists essentially of potassium carbonate. "Consisting essentially of" means that in each case, based on the total weight of component C) in the reaction mixture R M component C) contains more than 99% by weight, preferably more than 99.5% by weight, particularly preferably more than 99.9% by weight of potassium carbonate. In a particularly preferred embodiment, component C) consists of potassium carbonate. As potassium carbonate, potassium carbonate having a volume weighted average particle size of less than 200 μm is particularly preferred. The volume weighted average particle size of potassium carbonate is determined in a suspension of potassium carbonate in N-methylpyrrolidone using a particle size analyzer. In a particular embodiment, the reaction mixture R M essentially does not contain the alkali metal hydroxide or alkaline earth metal hydroxide detailed above.

[0029] Component C) is present in an excess of at least 3 mol% relative to dihydroxy component B), in particular the excess of component C) is at least 4 mol%, specifically 5 mol% or more. In certain embodiments, it may be preferred if C) is used in an excess of at least 6 mol%, at least 7.5 mol%, at least 10 mol% or at least 12.5 mol% respectively. According to one embodiment, the excess of component C) relative to component B) is 3 mol% to 20 mol%, more specifically 4 to 20 mol%, even more specifically 5 to 20 mol%. According to certain embodiments, the excess of component C) relative to component B) is 3 mol% to 18 mol%, more specifically 3 to 15 mol%, even more specifically 3 to 13 mol%.

[0030] Reaction mixture R M contains at least one aprotic polar solvent as component D). The "at least one aprotic polar solvent" according to the present invention is understood to also mean exactly one aprotic polar solvent and a mixture of two or more aprotic polar solvents. Suitable aprotic polar solvents are selected from the group consisting of, for example, anisole, dimethylformamide, dimethyl sulfoxide, sulfolane, N-methylpyrrolidone, N-ethylpyrrolidone and N-dimethylacetamide. Preferably, component D) is selected from the group consisting of N-methylpyrrolidone, N-dimethylacetamide, dimethyl sulfoxide and dimethylformamide. As component D), N-methylpyrrolidone is particularly preferred.

[0031] According to one embodiment of the present invention, component D) used in the process of the present invention is selected from the group consisting of N-methylpyrrolidone, N-dimethylacetamide, dimethyl sulfoxide and dimethylformamide.

[0032] In particular, component D) is the reaction mixture R MBased on the total weight of component D) therein, it may be preferable to contain at least 50% by weight of at least one solvent selected from the group consisting of N-methylpyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, and dimethylformamide. As component D), N-methylpyrrolidone is particularly preferred. In a more preferred embodiment, component D) consists essentially of N-methylpyrrolidone. "Consisting essentially of" means that component D) contains at least one aprotic polar solvent selected from the group consisting of N-methylpyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, and dimethylformamide (N-methylpyrrolidone is preferred) in an amount exceeding 98% by weight, particularly preferably exceeding 99% by weight, more preferably exceeding 99.5% by weight. In a specific embodiment of the present invention, component D) consists of N-methylpyrrolidone. N-methylpyrrolidone is also called NMP or N-methyl-2-pyrrolidone.

[0033] In step I) of the process of the present invention, the reaction mixture R M is provided at an initial temperature T 1 . T 1 can be, for example, ambient temperature, for example 20 - 27 °C, particularly 20 - 25 °C, for example 21 °C, 22 °C, 23 °C, and 24 °C. The process is not limited to this T 1 , and T 1 may be 20 - 80 °C, or T 1 may simply be the temperature naturally present in the environment where the reaction occurs. A more important feature of the process of the present invention is the rate of temperature change from T 1 to the final reaction temperature T F .

[0034] According to step II) of the process of the present invention, the reaction mixture R M is heated at a rate of at least 0.4 K / min from the initial temperature T 1 to the final reaction temperature T F .

[0035] Therefore, the heating rate characterizing the process of the present invention is at least 0.4 K / min. In some cases, it may be preferable for the rate to be at least 0.45 K / min, more specifically at least 0.5 K / min. According to a more specific embodiment of the present invention, the rate is at least 0.55 K / min, and even more specifically the rate is at least 0.6 K / min. The limit of the rate is given by the capabilities of the device in which the reaction is carried out and, of course, depends on whether the reaction is carried out on a laboratory scale or on a semi-industrial or industrial scale. The final reaction temperature T F depends on the exact reactants and the solvent(s) used, and the upper temperature limit is determined by the boiling point of at least one aprotic solvent (constituent D) at standard pressure (1013.25 mbar). T F is generally in the range of 80 to 250 °C, preferably 100 to 220 °C. T F may preferably be in the range of 130 °C to 200 °C, particularly 150 °C to 195 °C. A temperature T F in the range of 160 °C to 190 °C, for example 180 °C to 190 °C, may be preferred.

[0036] The process according to the present invention is generally carried out preferably at standard pressure. When T F is reached, the mixture is preferably held at this temperature for a time interval in the range of 2 to 12 hours, particularly 3 to 10 hours, and this time is referred to herein as the "reaction time".

[0037] As explained above and as generally known to those skilled in the art, in addition to the desired polymer (P), the product mixture P M also contains halide compounds formed during the conversion of the reaction mixture R M . Depending on the carbonate used as component C) and the aromatic dihalosulfone used as monomer B), for example potassium chloride can be formed during the reaction.

[0038] In one embodiment, the halide compound is removed from the product mixture P after step II MSeparated from, the separation of the halide compound can be carried out by any method known to those skilled in the art, for example, via filtration or centrifugation. Thus, the present invention also provides the following steps: IIIa) Filtration of the product mixture (P M ) obtained in step II) and further provides a process comprising the same.

[0039] In step IIIa), the halide compound is removed, and a product mixture (P M ) substantially free of the halide compound is most preferably obtained. However, P M may still contain trace amounts of the halide compound. "Trace amounts of the halide compound" in this context means less than 0.5% by weight, preferably less than 0.1% by weight, and most preferably less than 0.01% by weight of each halide compound, based on the total weight of the product mixture P M . After step IIIa), the product mixture (P M ) usually contains at least 0.0001% (by weight, for example, at least 0.0005% by weight or at least 0.001% by weight) of the halide compound, based on the total weight of the product mixture (P M ).

[0040] The isolation of the polyarylene (ether) sulfone polymer (P) contained in the product mixture (P M ) obtained by the process according to the present invention can be carried out, for example, by precipitation of the product mixture (P M ) in water or a mixture of water and other solvents. Thereafter, the precipitated polyarylene (ether) sulfone polymer (P) can be extracted with water and then dried. In one embodiment of the present invention, the precipitate can also be incorporated into an acidic medium. Suitable acids are, for example, organic acids or inorganic acids, such as carboxylic acids such as acetic acid, propionic acid, succinic acid or citric acid, and mineral acids such as hydrochloric acid, sulfuric acid or phosphoric acid.

[0041] Thus, in a further embodiment, the present invention also provides the following steps: IIIb) The product mixture (P MIsolation of poly(arylene(ether)sulfone) polymer (P) from also provides a process comprising.

[0042] Step IIIb) is optional and can be carried out after step II) or step IIIa) if filtration in IIIa) is part of the process.

[0043] As used herein, "polymer" can mean a homopolymer or copolymer, or a mixture thereof. One of ordinary skill in the art will recognize that any polymer may be essentially a homopolymer or a copolymer, but typically is a mixture of polymer individuals with different configurations such as chain length, degree of branching or nature of end groups. Thus, hereinafter, "at least 1" as a prefix of a polymer may include different types of polymers, whereby each type may have differences in the above configurations.

[0044] The poly(arylene(ether)sulfone) obtained by the process of the present invention is a class of polymers generally known to those skilled in the art. The poly(arylene(ether)sulfone) may preferably be composed of units of general formula II. [Chemical formula] (wherein the symbols t, q, Q, T, Y, Ar and Ar 1 are defined as follows. t, q are independently of each other 0, 1, 2 or 3, Q, T, Y are independently of each other a chemical bond, or a group selected from -O-, -S-, -SO2-, S=O, C=O, -N=N- and -CR a R b - wherein R a and R b are independently of each other a hydrogen atom, (C1-C 12 ) alkyl, (C1-C 12 ) alkoxy, (C3-C 12 ) cycloalkyl or (C6-C 18) is an aryl group, where at least one of Q, T, and Y is present and is -SO2-, Ar and Ar 1 are, independently of each other, (C6 - C 18 ) arylene. )

[0045] Within the above preconditions, when Q, T, or Y is a chemical bond, this means that the adjacent group on the left and the adjacent group on the right are directly linked to each other through a chemical bond.

[0046] According to a preferred embodiment, t and q are independently 0 or 1.

[0047] According to a preferred embodiment, Q, T, and Y in formula II are independently a chemical bond, -O-, -SO2-, and -CR a R b -, provided that at least one of Q, T, and Y is present and is -SO2-. Further, R a and R b are preferably, independently of each other, hydrogen or (C1 - C4) alkyl.

[0048] -CR a R b - in, R a and R b are preferably, independently of each other, hydrogen, (C1 - C 12 ) alkyl, (C1 - C 12 ) alkoxy, and (C6 - C 18 ) aryl.

[0049] (C1 - C 12 ) alkyl refers to a straight-chain or branched saturated hydrocarbon group having 1 to 12 carbon atoms. The following moieties, (C1 - C6) alkyl, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, 2- or 3-methylpentyl, and (C7 - C 12) Alkyl, for example, unbranched heptyl, octyl, nonyl, decyl, undecyl, lauryl, and their mono- or multi-branched analogs are particularly included.

[0050] The term "C1-C 12 -alkoxy" refers to a straight-chain or branched alkyl group having 1 to 12 carbon atoms bonded through oxygen at any position within the alkyl group, for example, methoxy, ethoxy, n-propoxy, 1-methylethoxy, butoxy, 1-methylpropoxy, 2-methyl-propoxy or 1,1-dimethylethoxy.

[0051] (C3-C 12 ) cycloalkyl refers to a monocyclic saturated hydrocarbon group having 3 to 12 carbon ring members, particularly (C3-C8) cycloalkyl, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclopropylmethyl, cyclopropylethyl, cyclopropylpropyl, cyclobutylmethyl, cyclobutylethyl, cyclopentylethyl, cyclopentylpropyl, cyclopentylbutyl, cyclopentylpentyl, cyclopentylhexyl, cyclohexylmethyl, cyclohexyldimethyl and cyclohexyltrimethyl.

[0052] Ar and Ar 1 are, independently of each other, (C6-C 18 )-arylene groups. According to a particular embodiment, Ar 1 may preferably be an unsubstituted (C6-C 12 ) arylene group.

[0053] Ar and Ar 1 are preferably independently selected from phenylene, bisphenylene and naphthylene groups, and arylene groups derived from anthracene, from phenanthrene or from naphthacene. For example, Ar and Ar 1independently selected from 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 1,6-naphthylene, 1,7-naphthylene, 2,6-naphthylene and 2,7-naphthylene, 2,7-dihydroxynaphthylene and 4,4'-bisphenylene.

[0054] In particular, Ar and Ar 1 are independently selected from phenylene and naphthylene groups, for example independently selected from 1,2-phenylene, 1,3-phenylene, 1,4-phenylene, 1,6-naphthylene, 1,7-naphthylene, 2,6-naphthylene and 2,7-naphthylene, more specifically preferably independently selected from 1,4-phenylene, 1,3-phenylene and naphthylene. Further, according to another embodiment of the present invention, Ar and Ar 1 are independently selected from arylene groups derived from anthracene, from phenanthrene, or from naphthacene. Still further, according to a further embodiment, Ar and Ar 1 are independently selected from 2,7-dihydroxynaphthylene and 4,4'-bisphenylene.

[0055] The polyarylene (ether) sulfone may preferably contain at least one of the following repeating units IIa to IIo.

Chemical formula

Chemical formula

[0056] In addition to the units IIa to IIo that may preferably be present, the other repeating units are those in which one or more 1,4-phenylene units derived from hydroquinone are replaced by 1,3-phenylene units derived from resorcinol, or naphthylene units derived from dihydroxynaphthalene.

[0057] Particularly preferred units of general formula II are units IIa, IIg and / or IIk. According to certain embodiments, it is particularly preferred that the polyarylene(ether)sulfone consists essentially of one type of unit of general formula II, said one type being particularly selectable from IIa, IIg and IIk.

[0058] According to a preferred embodiment, the polyarylene(ether)sulfone is composed of repeating units in which Ar is 1,4-phenylene, t is 1, q is 0, T is a chemical bond and Y is SO2. This polyarylene(ether)sulfone is also referred to as polyphenylene sulfone (PPSU) (formula IIg).

[0059] According to a more preferred embodiment, the polyarylene(ether)sulfone is composed of repeating units in which Ar is 1,4-phenylene, t is 1, q is 0, T is C(CH3)2 and Y is SO2. This polyarylene(ether)sulfone is also referred to as polysulfone (PSU) (formula IIa).

[0060] According to an even more preferred embodiment, the polyarylene(ether)sulfone is composed of repeating units in which Ar is 1,4-phenylene, t is 1, q is 0, and T and Y are SO2. This polyarylene(ether)sulfone is also referred to as polyether sulfone (PESU) (formula IIk).

[0061] For the purposes of the present disclosure, abbreviations such as PPSU, PESU and PSU comply with DIN EN ISO 1043-1:2001.

[0062] The polyarylene(ether)sulfone usually has halogen end groups, in particular -F or -Cl, or phenolic OH end groups or phenolate end groups, which may be present as such or in a reacted form, in particular in the form of -OCH3 end groups. The amount of phenolic end groups can be determined by potentiometric titration.

[0063] For the purposes of the present invention, the expression "phenolic end group" means a hydroxy group bonded to an aromatic ring and which may also be present in deprotonated form. Those skilled in the art will recognize that a phenolic end group can also take the form of what is known as a phenolate end group as a result of cleavage of a proton upon exposure to a base. Thus, the expression "phenolic end group" explicitly includes not only aromatic OH groups but also phenolate groups.

[0064] The proportion of phenolic end groups is preferably determined by potentiometric titration. For this purpose, the polymer is dissolved in dimethylformamide and titrated with a solution of tetrabutylammonium hydroxide in toluene / methanol. The end point is recorded with a potentiometer. The proportion of halogen end groups is preferably determined by elemental analysis. The amount of methoxy groups can be 1 determined by 1H-NMR. These techniques are well known to those skilled in the art.

[0065] The polyarylene(ether)sulfone polymer (P) obtainable by the process of the present invention preferably has a weight average molecular weight (Mw) in the range of 15,000 to 180,000 g / mol, more preferably in the range of 20,000 to 150,000 g / mol, and particularly preferably in the range of 25,000 to 125,000 g / mol as determined by GPC (gel permeation chromatography). The GPC analysis is carried out using dimethylacetamide containing 0.5 wt% LiBr as the solvent, and the polymer concentration is 4 mg / mL. The system was calibrated with PMMA standards. As columns, three different polyester copolymer-based units were used. After dissolving the material, the resulting solution was filtered using a filter with a pore size of 0.2 μm, then 100 μL of the solution was injected into the system, and the elution rate was set at 1 mL / min. The polyarylene(ether)sulfone polymer (P) obtainable by the process of the present invention further preferably has a number average molecular weight (Mn) in the range of 5,000 to 75,000 g / mol, more preferably in the range of 6,000 to 60,000 g / mol, and particularly preferably in the range of 7,500 to 50,000 g / mol as determined by GPC (gel permeation chromatography). The GPC analysis is carried out as described above. The glass transition temperature (Tg) of the polyarylene(ether)sulfone polymer (P) is determined by differential scanning calorimetry (DSC) at a heating rate of 10 K / min in the second heating cycle and is typically in the range of 180 to 260 °C, preferably in the range of 180 to 255 °C, and particularly preferably in the range of 180 to 250 °C. The viscosity number (V.N.) of the polyarylene(ether)sulfone polymer (P) is determined as a 1% solution in N-methylpyrrolidone at 25 °C. The viscosity number (V.N.) is particularly in the range of 65 to 120 ml / g, typically >65 ml / g, preferably in the range of 66 to 100 ml / g, and most preferably in the range of 70 to 90 ml / g.

[0066] Surprisingly, by following the process parameters of the present invention described in detail herein, the process of the present invention results in a very small amount of cyclic dimer without subsequent purification steps. A "cyclic dimer" is an undesirable by-product that can form during polycondensation, and the linear condensation product from two monomers A) and two monomers B) reacts under ring closure.

[0067] In particular, the composition contains cyclic dimer in an amount of 1.1% by weight or less (0 to 1.1% by weight), particularly 1.0% by weight or less (0 to 1.0% by weight), more specifically 0.9% by weight or less (0 to 0.9% by weight).

[0068] According to one embodiment, the cyclic dimer content is 0.1 to 1.1% by weight, particularly 0.2 to 1.1% by weight, more specifically 0.3 to 1.1% by weight, and even more specifically 0.4 to 1.1% by weight. It may also be preferable when the cyclic dimer content is 0.5 to 1.1% by weight, particularly 0.6 to 1.1% by weight, more specifically 0.7 to 1.1% by weight, and even more specifically 0.8 to 1.1% by weight. Still further embodiments relate to polyarylene (ether) sulfone compositions obtainable by the process of the present invention wherein the cyclic dimer content is 0.9 to 1.1% by weight, particularly 1.0 to 1.1% by weight.

[0069] According to still further embodiments, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process of the present invention is 0.1 to 1.0% by weight, particularly 0.2 to 1.0% by weight, more specifically 0.3 to 1.0% by weight, and even more specifically 0.4 to 1.0% by weight. It may also be preferable when the cyclic dimer content is 0.5 to 1.0% by weight, particularly 0.6 to 1.0% by weight, more specifically 0.7 to 1.0% by weight, and even more specifically 0.8 to 1.0% by weight. Still further embodiments relate to polyarylene (ether) sulfone compositions obtainable by the process of the present invention wherein the cyclic dimer content is 0.9 to 1.0% by weight.

[0070] Still further embodiments relate to polyarylene (ether) sulfone compositions obtainable by the process of the invention, having a cyclic dimer content of from 0.1 to 0.9% by weight, in particular from 0.2 to 0.9% by weight, more specifically from 0.3 to 0.9% by weight, and even more specifically from 0.4 to 0.9% by weight. The cyclic dimer content may also preferably be from 0.5 to 0.9% by weight, in particular from 0.6 to 0.9% by weight, more specifically from 0.7 to 0.9% by weight, and even more specifically from 0.8 to 0.9% by weight.

[0071] According to still further embodiments, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process of the invention is from 0.1 to 0.8% by weight, in particular from 0.2 to 0.8% by weight, more specifically from 0.3 to 0.8% by weight, and even more specifically from 0.4 to 0.8% by weight. The cyclic dimer content may also preferably be from 0.5 to 0.8% by weight, in particular from 0.6 to 0.8% by weight, more specifically from 0.7 to 0.8% by weight.

[0072] According to still further embodiments, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process of the invention is from 0.1 to 0.7% by weight, in particular from 0.2 to 0.7% by weight, more specifically from 0.3 to 0.7% by weight, and even more specifically from 0.4 to 0.7% by weight. The cyclic dimer content may also preferably be from 0.5 to 0.7% by weight, in particular from 0.6 to 0.7% by weight.

[0073] According to still further embodiments, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process of the invention is from 0.1 to 0.6% by weight, in particular from 0.2 to 0.6% by weight, more specifically from 0.3 to 0.6% by weight, and even more specifically from 0.4 to 0.6% by weight. The cyclic dimer content may also preferably be from 0.5 to 0.6% by weight.

[0074] According to a further embodiment, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process of the present invention is 0.1 to 0.5% by weight, particularly 0.2 to 0.5% by weight, more specifically 0.3 to 0.5% by weight, and even more specifically 0.4 to 0.5% by weight.

[0075] According to a further embodiment, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process of the present invention is 0.1 to 0.4% by weight, particularly 0.2 to 0.4% by weight, more specifically 0.3 to 0.4% by weight.

[0076] According to a further embodiment, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process of the present invention is 0.1 to 0.3% by weight, particularly 0.2 to 0.3% by weight, more specifically 0.1 to 0.2% by weight.

[0077] Furthermore, by using the process of the present invention described in detail herein, it is surprising that very small amounts of cyclic oligomers different from cyclic dimers are also contained in the produced polymer product. This is achieved by the process itself without performing subsequent purification steps to remove oligomers from the reaction product. Generally, "cyclic oligomers" are undesirable by-products that can be formed during polycondensation, where linear condensation products of different lengths react under ring closure, for example, linear condensation products from: - Three monomers A) and three monomers B) react under ring closure (hereinafter "cyclic trimer"); - Four monomers A) and four monomers B) react under ring closure (hereinafter "cyclic tetramer"); - Five monomers A) and five monomers B) react under ring closure (hereinafter "cyclic pentamer"); - Six monomers A) and six monomers B) react under ring closure (hereinafter "cyclic hexamer"); - Seven monomers A) and seven monomers B) react under ring closure (hereinafter "cyclic heptamer"); - Eight monomers A) and eight monomers B) react under ring closure (hereinafter referred to as "cyclic octamer"); - Nine monomers A) and nine monomers B) react under ring closure (hereinafter referred to as "cyclic nonamer"); and / or - Ten monomers A) and ten monomers B) react under ring closure (hereinafter referred to as "cyclic decamer").

[0078] Each of the cyclic oligomers is preferably contained independently in the polymer of the present invention obtained by the process of the present invention in an amount of 1.1% by weight or less (0 to 1.1% by weight), particularly 1.0% by weight or less (0 to 1.0% by weight), more specifically 0.9% by weight or less (0 to 0.9% by weight). The preferred ranges given for the cyclic dimer above apply independently to each cyclic oligomer (trimer, tetramer, pentamer, hexamer, heptamer, octamer, nonamer, decamer).

[0079] The content of the cyclic oligomer can be determined, for example, by size exclusion chromatography well known to those skilled in the art. For example, individual cyclic oligomers can be identified by Maldi-TOF mass spectrometry. The cyclic oligomers have no end groups and can thus be distinguished from linear oligomers which also have a low molecular weight compared to the desired polymer product.

[0080] Furthermore, it is also surprising that the process parameters of the present invention result in a polyarylene (ether) sulfone polymer (P) with a very low content of aromatic volatile substances without performing a subsequent purification step to remove the aromatic volatile substances from the reaction product. The "aromatic volatile substances" to be avoided as contaminants in the polyarylene (ether) sulfone polymer (P) are selected, for example, from toluene, ethylbenzene, o-xylene, m-xylene, p-xylene and chlorobenzene.

[0081] The product of the process of the present invention preferably contains each of the aromatic volatile substances detailed above in an amount of less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, and even more specifically less than 20 ppm, based on the total weight of the polymer product, and the amount is applied independently for each of the volatile substances. More preferably, the product of the process of the present invention preferably contains each of the aromatic volatile substances detailed above in an amount of less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, and even more specifically less than 3 ppm, based on the total weight of the polymer product, and the amount is applied independently for each of the volatile substances.

[0082] In a very specific embodiment, the product of the process of the present invention preferably contains the aromatic volatile substances detailed above in a total amount of less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, and even more specifically less than 20 ppm. More preferably, the product of the process of the present invention preferably contains the aromatic volatile substances detailed above in a total amount of less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, and even more specifically less than 3 ppm.

[0083] According to one embodiment, the product of the process of the present invention preferably contains chlorobenzene in an amount of less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, and even more specifically less than 20 ppm, based on the total weight of the polymer product. More preferably, the product of the process of the present invention preferably contains chlorobenzene in an amount of less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, and even more specifically less than 3 ppm, based on the total weight of the polymer product.

[0084] According to a further embodiment, the product of the process of the present invention contains preferably less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, and even more specifically less than 20 ppm of toluene, based on the total weight of the polymer product. More preferably, the product of the process of the present invention contains preferably less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, and even more specifically less than 3 ppm of toluene, based on the total weight of the polymer product.

[0085] According to yet a further embodiment, the product of the process of the present invention contains preferably less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, and even more specifically less than 20 ppm of chlorobenzene and toluene, based on the total weight of the polymer product. More preferably, the product of the process of the present invention contains preferably less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, and even more specifically less than 3 ppm of chlorobenzene and toluene, based on the total weight of the polymer product.

[0086] In particular, the polyarylene (ether) sulfone composition obtainable by the process of the present invention is essentially free of chlorobenzene. In a further embodiment, the polyarylene (ether) sulfone composition obtainable by the process of the present invention is essentially free of toluene. According to a further embodiment, the polyarylene (ether) sulfone composition obtainable by the process of the present invention is essentially free of toluene and chlorobenzene. According to yet a further embodiment, the polyarylene (ether) sulfone composition obtainable by the process of the present invention is essentially free of aromatic volatile substances as defined above in particular. The term "essentially free of" in this context is understood to mean that the product may contain only negligible traces of each aromatic volatile substance.

[0087] It is more preferable that the polyarylene (ether) sulfone does not contain chlorobenzene. It is further preferable that the polyarylene (ether) sulfone does not contain toluene, and it is even more preferable that the polyarylene (ether) sulfone does not contain chlorobenzene or toluene. It is particularly preferable that the polyarylene (ether) sulfone does not contain any of the aromatic volatile substances listed above.

[0088] Therefore, a further object of the present invention is a polyarylene (ether) sulfone composition obtainable by the process of the present invention described herein. In particular, the polyarylene (ether) sulfone of the present invention has a defined, preferably a high molecular weight (e.g., V.N. > 65 ml / g) as defined above, a defined, preferably a cyclic dimer content as defined above, and a low content with respect to aromatic volatile substances such as chlorobenzene (including preferred embodiments) detailed above.

[0089] A further advantage of the process of the present invention is to produce a high-purity first polyarylene (ether) sulfone polymer (P) measurable by the turbidity of the polymer product. The method for measuring turbidity is well known to those skilled in the art.

[0090] The purity of the product can be characterized, for example, by turbidity measurement using a solution containing a polymer in 20 wt% DMF using a Hach TL2360 photometer. This device is calibrated internally and the results are given in the range of 0 - 40 N.T.U. (nephelometric turbidity units) as "N.T.U.". The solution is preferably prepared and then equilibrated for 24 hours before measurement. Then, after some storage time of the solution, for example, after storage in the dark for 7 days, a second measurement may be performed. The result of this second measurement is particularly very meaningful for determining whether the polymer is suitable for industrial applications, such as the production of membranes.

[0091] According to a preferred embodiment of the present invention, the poly(arylene)(ether)sulfone polymer (P) obtained from the process of the present invention exhibits a turbidity of 0 to 1.75, preferably 0 to 1.74, after 24 hours using a Hach TL2360 photometer and the method described above. Further, according to a further preferred embodiment, the poly(arylene)(ether)sulfone polymer (P) obtained from the process of the present invention exhibits a turbidity of 0 to 1.95, preferably 0 to 1.90, after 7 days using a Hach TL2360 photometer and the method described above. According to a more preferred embodiment, the turbidity of the first (24 hours) and second (7 days) measurements using a Hach TL2360 photometer and the method described above is 0 to 1.95, preferably 0 to 1.90.

[0092] Low turbidity makes the product very suitable for use in membranes. Certain process parameters of the process of the present invention result in a polymer having good turbidity values without the need to remove such impurities in subsequent purification steps.

[0093] As described above, particularly due to the low content of cyclic dimers and aromatic volatiles, and the favorable purity of the poly(arylene)(ether)sulfone of the present invention, it is very suitable for use in the membrane production process, particularly when the membrane is produced from a solution.

[0094] Those skilled in the art are proficient in the preparation of membranes. During the preparation of the membrane, solvent exchange is usually known to result in an asymmetric membrane structure. Therefore, the membrane is preferably asymmetric. In an asymmetric membrane, the pore size increases from the upper layer used for separation to the bottom of the membrane.

[0095] When the membrane is a porous membrane, the membrane typically contains pores. The pores are usually determined by filtration experiments using solutions containing different PEGs covering a molecular weight range of 300 to 1,000,000 g / mol and have a diameter in the range of 1 nm to 10,000 nm, preferably in the range of 2 to 500 nm, particularly preferably in the range of 5 to 250 nm. By comparing the GPC traces of the feed and the filtrate, the retention of the membrane for each molecular weight can be determined. The molecular weight at which the membrane shows a 90% retention rate is regarded as the molecular weight cut-off (MWCO) of this membrane under given conditions. Using the known correlation between the Stokes diameter of PEGs and their molecular weights, the average pore diameter of the membrane can be determined. Details regarding this method are described in the literature (Chung, J. Membr. Sci. 531 (2017) 27 - 37). When the membrane is prepared by the phase inversion process, a porous membrane is typically obtained.

[0096] High-density membranes typically contain substantially no pores. High-density membranes are typically obtained by a solution casting process that evaporates the solvent contained in the cast solution. Usually, the separation layer (the solution that gives the membrane after separation of the solvent) is cast on a support, which may be another polymer such as polysulfone or cellulose acetate. A layer of polydimethylsiloxane may be applied on top of the separation layer.

[0097] The membrane can have any thickness. For example, the thickness of the membrane is in the range of 2 to 150 μm, preferably in the range of 3 to 100 μm, and most preferably in the range of 5 to 60 μm. The membranes of the present invention can be used in any process known to those skilled in the art in which the membrane is used. In particular, when the membrane is a high-density membrane, it is particularly suitable for gas separation.

[0098] Accordingly, the object of the present invention is for use in membranes of polyarylene (ether) sulfone polymer (P) or polyarylene (ether) sulfone polymer (P) compositions obtained by the process of the present invention.

[0099] According to one embodiment of the present invention, the polyarylene (ether) sulfone polymer (P) of the present invention is used for an asymmetric membrane. In a further embodiment, the membrane is porous.

[0100] In yet another embodiment of the present invention, the polyarylene (ether) sulfone polymer (P) is used in a high-density membrane. Thus, another object of the present invention is also a membrane in which the membrane is a high-density membrane.

[0101] Another object of the present invention is also the use of the polyarylene ether (sulfone) polymer (P) obtainable by the process of the present invention in the manufacture of a membrane, the manufacture including phase inversion from a solution.

[0102] When the membrane is a porous membrane, the membrane is particularly suitable for nanofiltration, microfiltration and / or ultrafiltration. Typical nanofiltration, ultrafiltration and microfiltration processes are known to those skilled in the art. For example, the membrane can be used in a dialysis process as a dialysis membrane. The polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention is particularly suitable for the manufacture of dialysis membranes.

[0103] Thus, another object of the present invention is the use of the polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention in the manufacture of a membrane, particularly for the manufacture of nanofiltration membranes, ultrafiltration membranes and / or microfiltration membranes. According to a specific embodiment, the polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention is used for the manufacture of an ultrafiltration membrane such as a dialysis membrane. According to a further embodiment, the polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention is used for the manufacture of a gas separation membrane.

[0104] A further object of the present invention is a membrane comprising a polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention described herein. In particular, the membrane is a nanofiltration membrane, an ultrafiltration membrane and / or a microfiltration membrane, more specifically an ultrafiltration membrane. According to a further embodiment, the membrane comprising a polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention described herein is a gas separation membrane.

[0105] The membrane can be prepared from the polyarylene (ether) sulfone polymer (P) obtained according to the present invention by any method known to those skilled in the art.

[0106] A further object of the present invention is a method for preparing a membrane comprising a polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention, i) providing a solution comprising a polyarylene (ether) sulfone polymer (P) and at least one solvent; ii) separating at least one solvent from the solution to obtain a membrane which method comprises.

[0107] At least one solvent in step i) may be exactly one solvent or a mixture of two or more solvents. The solution in step i) can be provided in a conventional container that may include, for example, a stirring device and preferably a temperature control device, by any method known to those skilled in the art. Preferably, the solution is provided by dissolving the polyarylene(ether)sulfone polymer (P) in at least one solvent, preferably with stirring. Step i) is preferably carried out at a high temperature, particularly in the range of 20 to 120 °C, more preferably in the range of 40 to 100 °C. Those skilled in the art will select the temperature according to at least one solvent. The solution preferably contains the polyarylene(ether)sulfone polymer (P) completely dissolved in at least one solvent. This means that the solution (S) preferably does not contain solid particles of the polyarylene(ether)sulfone polymer (P) and the polyarylene(ether)sulfone polymer (P) cannot be separated from at least one solvent, preferably by filtration. The solution preferably contains 0.001 to 50% by weight of the polyarylene(ether)sulfone polymer (P) based on the total weight of the solution. More preferably, the solution in step i) contains 0.1 to 30% by weight of the polyarylene(ether)sulfone polymer (P) based on the total weight of the solution, and most preferably the solution contains 0.5 to 25% by weight of the polyarylene(ether)sulfone polymer (P). As at least one solvent, any solvent known to those skilled in the art for the polyarylene(ether)sulfone polymer (P) is suitable. Preferably, at least one solvent is soluble in water. Thus, at least one solvent is preferably selected from the group consisting of N-methylpyrrolidone, dimethylacetamide, dimethylsulfoxide, dimethyllactamide, dimethylformamide and sulfolane. N-methylpyrrolidone and dimethyllactamide are particularly preferred. As at least one solvent, dimethyllactamide is most preferred.The solution preferably contains at least one solvent in the range of 50 to 99.999% by weight, more preferably in the range of 70 to 99.9% by weight, and most preferably in the range of 75 to 99.5% by weight, based on the total weight of the solution.

[0108] The solution provided in step i) can further contain additives for membrane preparation.

[0109] Additives suitable for membrane preparation are known to those skilled in the art and include, for example, polyvinylpyrrolidone (PVP), polyethylene oxide (PEO), polyethylene oxide - polypropylene oxide copolymer (PEO - PPO), and poly(tetrahydrofuran) (poly - THF). Polyvinylpyrrolidone (PVP) and polyethylene oxide (PEO) are particularly preferred as additives for membrane preparation. The additives for membrane preparation can be contained in the solution, for example, in an amount in the range of 0.01 to 20% by weight, preferably in the range of 0.1 to 15% by weight, and more preferably in the range of 1 to 10% by weight, based on the total weight of the solution. It will be apparent to those skilled in the art that the weight percentages of the polyarylene(ether)sulfone polymer (P), at least one solvent, and optionally the additives for membrane preparation (if any) typically total 100% by weight.

[0110] The duration of step i) can vary within a wide range. The duration of step i) is preferably in the range of 10 minutes to 48 hours (h), particularly in the range of 10 minutes to 24 hours, and more preferably in the range of 15 minutes to 12 hours. Those skilled in the art will select the duration of step i) to obtain a homogeneous solution.

[0111] In step ii), at least one solvent is separated from the solution to obtain a membrane. Before separating at least one solvent from the solution in step ii), it is possible to filter the solution provided in step i) to obtain a filtered solution. The following embodiments and preferences for separating at least one solvent from the solution are equally applicable for separating at least one solvent from the filtered solution used in this embodiment of the present invention. The separation of at least one solvent from the solution can be carried out by any method known to those skilled in the art suitable for separating the solvent from the polymer. Preferably, the separation is carried out via a phase inversion process. When the separation of at least one solvent is carried out via a phase inversion process, the resulting membrane is typically a porous membrane. The phase inversion process within the context of the present invention means the process by which the dissolved poly(arylene)(ether)sulfone polymer (P) is converted into a solid phase. Thus, the phase inversion process can also be called a precipitation process. Those skilled in the art know appropriate phase inversion processes. The phase inversion process can be carried out, for example, by cooling the solution, and the poly(arylene)(ether)sulfone polymer (P) contained in this solution precipitates. Another possibility for carrying out the phase inversion process is to bring the solution into contact with a gaseous liquid that is a non-solvent for the poly(arylene)(ether)sulfone polymer (P). Then, the poly(arylene)(ether)sulfone polymer (P) also precipitates. Suitable gaseous liquids that are non-solvents for the poly(arylene)(ether)sulfone polymer (P) are, for example, the protic polar solvents described below in their gaseous state. Another phase inversion process preferred within the context of the present invention is phase inversion by immersing the solution in at least one protic polar solvent. Thus, in one embodiment of the present invention, in step ii), at least one solvent contained in the solution is separated from the poly(arylene)(ether)sulfone polymer (P) by immersing the solution in at least one protic polar solvent. Thereby, a membrane is formed. Suitable at least one protic polar solvent is known to those skilled in the art. The at least one protic polar solvent is preferably a non-solvent for the poly(arylene)(ether)sulfone polymer (P).Preferred at least one protic polar solvent is water, methanol, ethanol, n-propanol, isopropanol, glycerol, ethylene glycol, and mixtures thereof. Step ii) typically includes providing the solution in a form corresponding to the morphology of the film obtained in step ii). Thus, in one embodiment of the present invention, step ii) includes casting the solution to obtain a film of the solution, or passing the solution through at least one spinneret to obtain at least one hollow fiber of the solution. Thus, in one preferred embodiment of the present invention, step ii) is the following step:. ii-1) Casting the solution provided in step i) to obtain a film of the solution; ii-2) Evaporating at least one solvent from the film of the solution obtained in step ii-1) to obtain a film in the form of a membrane including.

[0112] This means that the membrane is formed by evaporating at least one solvent from the film of the solution. In step ii-1), the solution can be cast by any method known to those skilled in the art. Typically, the solution is cast with a casting knife heated to a temperature in the range of 20 to 150 °C, preferably in the range of 40 to 100 °C. The solution is typically cast onto a substrate that does not react with the polyarylene (ether) sulfone polymer (P) or at least one solvent contained in the solution. Suitable substrates are known to those skilled in the art and are selected, for example, from polymer fabrics such as glass plates and non-woven materials. To obtain a high-density membrane, the separation in step ii) is typically carried out by evaporation of at least one solvent contained in the solution.

[0113] The resulting membrane preferably contains at least 50% by weight, more preferably at least 70% by weight, and most preferably at least 90% by weight of the polyarylene (ether) sulfone polymer (P), based on the total weight of the membrane. In a further preferred embodiment, the membrane consists essentially of the polyarylene (ether) sulfone polymer (P). "Consisting essentially of" means that the membrane contains more than 95% by weight, preferably more than 97.5% by weight, and most preferably more than 98% by weight of the polyarylene (ether) sulfone polymer (P), based on the total weight of the membrane.

[0114] During the formation of the membrane, the polyarylene (ether) sulfone polymer (P) is separated from at least one solvent. Thus, the resulting membrane essentially does not contain at least one solvent. In the context of the present invention, "essentially does not contain" means that the membrane contains at most 1% by weight, preferably at most 0.5% by weight, and particularly preferably at most 0.1% by weight of at least one solvent, based on the total weight of the membrane. The membrane contains at least 0.0001% by weight, preferably at least 0.001% by weight, and particularly preferably at least 0.01% by weight of at least one solvent, based on the total weight of the membrane.

[0115] The embodiments and preferences given for the polyarylene (ether) sulfone polymer (P) obtained from the process of the present invention apply mutatis mutandis independently to the polyarylene (ether) sulfone polymer (P) used in the membrane.

Examples

[0116] The following examples provide further illustration of the present invention without limiting the present invention.

[0117] The viscosity number of the obtained polyaryl (ether) sulfone is obtained by measuring in N-methylpyrrolidone (1 g in 100 ml solution; 25 °C) according to ISO 1628.

[0118] The content of the cyclic oligomer was detected by size exclusion chromatography using THF as the solvent. Separation was carried out by applying a combination of two columns with a length of 30 cm. The first column was filled with Plgel Mixed-E (registered trademark), and the second column was filled with PLgel Mixed-E (registered trademark). Separation was performed at 30 °C and a flow rate of 1 ml / min. For detection, a UV detector operating at 254 nm was used. Dichloromethane was used as the solvent for the detection of cycles in the polyethersulfone.

[0119] The purity of the product was further characterized by turbidity measurement using a solution containing a polymer in 20 wt% DMF using a Hach TL2360 photometer. The device was calibrated internally, and the results are given as "N.T.U." (nephelometric turbidity units) in the range of 0 - 40 N.T.U. with an accuracy of + / - 2% of the measured value. The solution was prepared and then equilibrated for 24 hours before measurement. The solution was then stored in the dark for 7 days and then the measurement was repeated.

[0120] The content of chlorobenzene was determined by GC analysis. For this purpose, 0.250 g of the polymer was placed in a headspace-vial and 1 ml of DMAc was added. The vial was rolled until the material was completely dissolved. The vial was then heated to 90 °C for 1 hour and the gas phase was analyzed using a GC system equipped with a DB WAX column and an FID detector.

[0121] Example C1 In a 4-liter glass reactor equipped with a thermometer, a gas inlet tube, and a Dean-Stark trap, 608.78 g (2.12 mol) of DCDPS, 483.97 g (2.12 mol) of bisphenol A, and 307.65 g (2.226 mol) of potassium carbonate with a volume average particle size of 33 μm were suspended in 1000 ml of NMP at 23 °C under a nitrogen atmosphere.

[0122] The mixture was heated to 190 °C within 270 minutes. In the following, the reaction time should be understood as the time during which the reaction mixture was maintained at 190 °C. The water formed in the reaction was continuously removed by distillation and the evaporated NMP was replenished.

[0123] After a reaction time of 7 hours, 1400 ml of NMP was added and the reaction was stopped (within 1 hour) by cooling to 130 °C. The mixture was then reacted with methyl chloride at this temperature for 45 minutes, the mixture was cooled to room temperature and stripped with nitrogen. The potassium chloride formed in the reaction was removed by filtration. The resulting polymer solution was then precipitated in water, the resulting polymer beads were separated and then extracted with hot water (85 °C) for 20 hours. The beads were then dried under reduced pressure (<100 mbar) at 120 °C for 24 hours.

[0124] The details of the reaction conditions for all other tests are summarized in Table 1. C1, C2, C5 and C8 are comparative examples that do not use the combinations of process parameters found according to the present invention.

Table 1

[0125] The materials prepared according to the claimed conditions exhibit a unique combination of properties such as high V.N., low dimer content, excellent purity, as shown by nephelometry, and do not contain chlorobenzene. (C9 = material: Udel P-3500 LCD commercially available from Solvay)

Claims

1. A method for preparing a polyarylene (ether) sulfone polymer (P), comprising: I) Starting temperature T １ in the reaction mixture R Ｍ is a step of providing, wherein the reaction mixture is A) at least one aromatic dihalogen sulfone; B) at least one dihydroxy component; C) at least 3 mol% excess of at least one carbonate component relative to the dihydroxy component B); D) at least one aprotic solvent; and said reaction mixture R Ｍ a step in which the initial concentration of each of monomers A) and B) in said reaction mixture is from 2.2 to 2.7 mol per liter of said at least one aprotic solvent D); and II) the reaction mixture R Ｍ from the starting temperature T １ to a final reaction temperature T Ｆ by heating at a rate of at least 0.4 K / min, a product mixture P Ｍ is obtained, step a method comprising the above.

2. The method according to claim 1, wherein A) is at least one dihalodiphenyl sulfone.

3. The method according to claim 1 or 2, wherein the at least one dihydroxy component B) is selected from dihydroxybiphenyl, bisphenol propane and bisphenol sulfone.

4. The method according to any one of claims 1 to 3, wherein the component D) is selected from N-methylpyrrolidone, N-dimethylacetamide, dimethyl sulfoxide and dimethylformamide.

5. Use of the polyarylene (ether) sulfone polymer (P) obtained by the method according to any one of claims 1 to 4 in a membrane.

6. Use of the polyarylene (ether) sulfone polymer (P) obtained by the method according to any one of claims 1 to 4 in the manufacture of a membrane.

7. The use according to claim 5 or 6, wherein the membrane is a nanofiltration membrane, an ultrafiltration membrane or a microfiltration membrane.

8. The use according to claim 5 or 6, wherein the membrane is a gas separation membrane.

9. A membrane comprising the polyarylene (ether) sulfone polymer (P) obtained by the method according to any one of claims 1 to 4.

10. The polyarylene (ether) sulfone obtained by the method according to any one of claims 1 to 4.

11. The polyarylene (ether) sulfone according to claim 10, having an intrinsic viscosity exceeding 65 ml / g and a cyclic dimer content of 1.1 wt% or less.

12. The polyarylene (ether) sulfone according to claim 10 or 11, containing 100 ppm or less of chlorobenzene.

13. The polyarylene (ether) sulfone according to any one of claims 10 to 12, showing a turbidity of 0 to 1.75, preferably 1.74 N.T.U. after 24 hours when using a Hach TL2360 photometer.

14. The turbidity after 24 hours and the turbidity after 7 days are from 0 to 1.95, preferably from 0 to 1.90 N.T.U., as measured using a Hach TL2360 photometer, for the poly(arylene)(ether)sulfone according to any one of claims 10 to 13.

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