Process for producing polyarylene (ether) sulfones with improved properties

Abstract

The present invention relates to a process for the production of polyarylene (ether) sulfones having high molecular weight and excellent purity as well as low content of undesired volatiles and reduced content of cyclic oligomers, the polyarylene (ether) sulfones obtained by the process of the invention, and parts, such as membranes, made from the polyarylene (ether) sulfones of the invention.

Description

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

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

[0003] The production of polyarylene (ether) sulfones can be carried out using the so-called "hydroxide method", in which the phenolate is formed by the reaction of the dihydroxy monomer component and a hydroxide. Another method is the so-called "carbonate route", in which the monomers are dissolved in a solvent and potassium carbonate is then added. General information about both synthesis methods can be found in the literature (e.g. RN Johnson et al., J. Polym. Sci. A-1 5 (1967) 2375, JEM McGrath et al., Polymer 25 (1984) 1827).

[0004] Processes for preparing polyarylene (ether) sulfones based on aromatic dihalogen compounds and aromatic bisphenols or their salts in the presence of at least one alkali metal carbonate or alkali metal bicarbonate, ammonium carbonate or ammonium bicarbonate in an aprotic solvent are well known (see, for example, US 4 870 153, EP 113 112, EP-A 297 363 and EP-A 135 130, WO 2019 / 002226, WO 2013 / 020871 and WO 2014 / 177638). Among them, particularly suitable monomers, catalysts and solvents, suitable component ratios, reaction conditions such as temperature, pressure, mixing conditions and post-treatment conditions can be found.

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

[0006] The object of the present invention is to provide a method for producing high molecular weight polyarylene (ether) sulfones containing very low levels of cyclic oligomers, in particular cyclic dimers. In addition, an object is to provide polyarylene (ether) sulfones containing small amounts of aromatic volatiles (such as toluene and / or chlorobenzene) and showing high purity. In particular, polyarylene (ether) sulfone polymers should be suitable for use in membranes.

[0007] The problem is solved by a process for preparing polyarylene (ether) sulfone (P), which comprises the following steps:

[0008] I) At the starting temperature T 1 The reaction mixture R M , the reaction mixture comprises

[0009] A) at least one aromatic dihalosulfone;

[0010] B) at least one dihydroxy component;

[0011] C) at least 3 mol % excess of at least one carbonate component relative to the dihydroxy component B); and

[0012] D) at least one aprotic solvent;

[0013] wherein the reaction mixture R M The initial concentration of each of monomers A) and B) in

[0014] 2.2 mol to 2.7 mol per liter of the at least one aprotic solvent D); and

[0015] II) the reaction mixture R is heated at a rate of at least 0.4 K / min. M From the starting temperature T 1 Heated to the final reaction temperature T F , wherein a product mixture (P M ).

[0016] It has been surprisingly found that the process of the invention produces high molecular weight polyarylene (ether) sulfone polymers having a particularly low content of cyclic dimers and high purity, in particular having a low turbidity and showing a desired low content of aromatic volatiles (such as chlorobenzene). The process of the invention produces low contents of cyclic oligomers, low contents of undesirable particles and volatiles causing turbidity, without the need to carry out a separate purification step to remove such substances from the polymer product. In addition, it has been found that the polymers obtained by the process of the invention are very suitable for the production of membranes, in particular in solution processes, since filter clogging does not occur during the processing of polymer solutions prepared by using these polymers.

[0017] According to the process of the invention, in step I), a reaction mixture R comprising components A), B), C and D) is provided. M In this document, each of components A) and B) may also be referred to as a "monomer" or they may also be referred to as "monomers" together. During the polycondensation reaction, component C) acts as a base to deprotonate component B), and component D) acts as a solvent. At the starting temperature T 1 The reaction mixture R M .

[0018] Reaction mixture R M is the mixture provided at the beginning of the reaction, ie before the actual process takes place, ie before the polycondensation between monomers A) and B). In the process of the invention, the reaction mixture R M Under the reaction conditions of the present invention, it is converted into a product mixture P M , wherein the reaction mixture R M Heated to a certain final reaction temperature T F The polycondensation reaction mainly occurs at this temperature. The polycondensation reaction produces the desired polyarylene (ether) sulfone polymer (P) product. The mixture obtained after the polycondensation occurs is also referred to as the product mixture P M The product mixture contains the desired polyarylene (ether) sulfone polymer (P), but generally also contains component D) and the reaction mixture R MIn the conversion of the reaction mixture, component C) deprotonates component B), and the deprotonated component B) reacts with component A), wherein a halide is formed.

[0019] The process according to the invention is carried out according to the so-called "carbonate method" and not according to the so-called "hydroxide method" with the separation of the phenoxide anion. M ) is substantially free of sodium hydroxide and potassium hydroxide. More preferably, according to this embodiment, the reaction mixture (R M ) is substantially free of alkali metal hydroxides and alkaline earth metal hydroxides. In this case, the term "substantially free" is understood to mean that based on the reaction mixture (R M ), the total weight of 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. In addition, it is preferred that the reaction mixture (R M ) does not contain toluene. Particularly preferably, the reaction mixture (R M ) does not contain any substance that forms an azeotrope with water.

[0020] In this article, "at least one" can generally mean one or two or more, such as three or four or five or more, wherein more can mean multiple or uncountable. For example, it can mean a mixture of one or two or more. If used with a compound, "at least one" means describing one or two or more compounds with different chemical compositions (i.e., chemical properties).

[0021] According to step I) of the process of the invention, the reaction mixture R M At least one aromatic dihalosulfone is contained as component A).

[0022] The at least one aromatic dihalosulfone A) is preferably at least one dihalogenated diphenyl sulfone. The present invention therefore also relates to a process in which the reaction mixture (R M ) comprises at least one dihalogenated diphenyl sulfone as component A). Based on the reaction mixture R M The total weight of component A) in the reaction mixture R M Preferably at least 50% by weight of dihalodiphenyl sulfone is contained as component A). Preferred dihalodiphenyl sulfones are selected from 4,4'-dihalodiphenyl sulfone. Particularly preferably, at least one component A) is selected from 4,4'-dichlorodiphenyl sulfone, 4,4'-difluorodiphenyl sulfone and 4,4'-dibromodiphenyl sulfone.

[0023] According to one embodiment, the at least one aromatic dihalosulfone of component A) is 4,4'-dichlorodiphenyl sulfone.

[0024] According to another embodiment, the at least one aromatic dihalosulfone of component A) is 4,4'-difluorodiphenyl sulfone.

[0025] Therefore, the present invention also relates to a process in which, based on the reaction mixture (R M ) in an amount of at least one aromatic dihalosulfone selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone.

[0026] In a particularly preferred embodiment, based on the reaction mixture (R M ) in the total weight of component A), component A) contains at least 80% by weight, preferably at least 90% by weight, more preferably at least 98% by weight of aromatic dihalosulfones selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone. In another particularly preferred embodiment, component A) consists essentially of at least one aromatic dihalosulfone selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone. In this case, "essentially consisting of..." is understood to mean that in each case based on the reaction mixture R M The total weight of component A) in the above embodiment, component A) 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 dihalosulfone selected from the group consisting of 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone. In the above embodiment, 4,4'-dichlorodiphenyl sulfone is particularly preferred as component A).

[0027] In a further particularly preferred embodiment, component A) consists of 4,4'-dichlorodiphenyl sulfone.

[0028] Reaction mixture R M The reaction mixture R comprises at least one dihydroxy component B). The dihydroxy component used is generally a component having two phenolic hydroxyl groups. M Containing at least one carbonate component, the reaction mixture R M The hydroxyl groups of component B) may be present partially in deprotonated form.

[0029] Component B) can be selected from the following compounds:

[0030] - dihydroxybenzenes, especially hydroquinone and resorcinol;

[0031] - dihydroxynaphthalene, in particular 1,5-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene and 2,7-dihydroxynaphthalene;

[0032] - dihydroxybiphenyls, especially 4,4'-biphenol and 2,2'-biphenol;

[0033] - bisphenyl ethers, in particular bis(4-hydroxyphenyl) ether and bis(2-hydroxyphenyl) ether;

[0034] - bisphenylpropanes, in particular 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane and 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane;

[0035] - bisphenylmethane, especially bis(4-hydroxyphenyl)methane;

[0036] - bisphenyl sulfones, especially bis(4-hydroxyphenyl)sulfone;

[0037] - bisphenyl sulfide, in particular bis(4-hydroxyphenyl) sulfide;

[0038] - bis(phenyl)ketones, in particular bis(4-hydroxyphenyl)ketone;

[0039] - bisphenylhexafluoropropane, in particular 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)hexafluoropropane; and

[0040] - bisphenylfluorene, especially 9,9-bis(4-hydroxyphenyl)fluorene.

[0041] Particularly preferably, the monomer component B) is selected from dihydroxybiphenyls such as 4,4′-biphenol, bisphenylpropanes such as 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) and bisphenyl sulfones such as bis(4-hydroxyphenyl)sulfone.

[0042] According to another preferred embodiment, the monomer component B) can also be selected from the group consisting of hydroquinone, resorcinol, dihydroxynaphthalene, especially 2,7-dihydroxynaphthalene, bisphenol A, dihydroxydiphenyl sulfone and 4,4'-biphenol.

[0043] According to another embodiment, trifunctional compounds can be used as component B). In this case, the result is a branched structure. If a trifunctional compound B) is used, preference is given to 1,1,1-tris(4-hydroxyphenyl)ethane.

[0044] The ratio of component A) to component B) is in principle derived from the stoichiometry of the polycondensation reaction, which is carried out theoretically with elimination of hydrogen chloride and is established by the person skilled in the art in a known manner. In order to control the end groups in the resulting end 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) can also be 1:1.

[0045] According to the present invention, it has been found that the reaction mixture R M The initial concentration of each monomer A) and B) in the mixture is critical and must be from 2.2 mol to 2.7 mol, in particular from 2.2 mol to 2.67 mol, more particularly from 2.2 mol to 2.65 mol, even more particularly from 2.2 mol to 2.6 mol, per liter of at least one aprotic solvent component D). According to another embodiment, if R M A monomer concentration of 2.2 mol to 2.55 mol, more particularly 2.2 mol to 2.5 mol, and even more particularly 2.2 mol to 2.45 mol per liter of at least one aprotic solvent component D) may be preferred. The preferred ranges apply independently to each of the monomers A) and B).

[0046] According to the process of the present invention, the reaction mixture R M At least one carbonate component is contained as component C) in an excess of at least 3 mol % relative to the dihydroxy component B).

[0047] "At least one carbonate component" is understood to mean exactly one carbonate component as well as mixtures 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. Preference is given to alkali metal carbonates and / or alkaline earth metal carbonates as metal carbonates. At least one metal carbonate selected from the group consisting of sodium carbonate, potassium carbonate and calcium carbonate is particularly preferred as metal carbonate. Potassium carbonate is most preferred. For example, based on the reaction mixture R M % of potassium carbonate. Therefore, another embodiment of the present invention is a process, wherein component C) comprises at least 50% by weight of potassium carbonate, based on the total weight of at least one carbonate component in the reaction mixture R. In a preferred embodiment, component C) consists essentially of potassium carbonate. "Essentially consisting of" is understood to mean that in each case, based on the total weight of the reaction mixture R MThe total weight of component C) in the reaction mixture R is preferably more than 99% by weight, preferably more than 99.5% by weight, and particularly preferably more than 99.9% by weight of potassium carbonate. In a particularly preferred embodiment, component C) consists of potassium carbonate. Potassium carbonate with a volume-weighted average particle size of less than 200 μm is particularly preferred as potassium carbonate. The volume-weighted average particle size of potassium carbonate is determined using a particle size analyzer on a suspension of potassium carbonate in N-methylpyrrolidone. In a specific embodiment, the reaction mixture R M It is substantially free of alkali metal hydroxides or alkaline earth metal hydroxides as described in detail above.

[0048] Relative to dihydroxy component B), component C) is present in an excess of at least 3 mol%, in particular component C) is in an excess of at least 4 mol%, in particular 5 mol% or more. In a specific embodiment, 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, component C) is in an excess of 3 mol% to 20 mol%, more specifically 4 mol% to 20 mol%, even more specifically 5 mol% to 20 mol%, relative to component B). According to a specific embodiment, component C) is in an excess of 3 mol% to 18 mol%, more specifically 3 mol% to 15 mol%, even more specifically 3 mol% to 13 mol%, relative to component B).

[0049] Reaction mixture R M At least one aprotic polar solvent is contained as component D). According to the invention, "at least one aprotic polar solvent" is understood to mean exactly one aprotic polar solvent and also mixtures of two or more aprotic polar solvents. Suitable aprotic polar solvents are, for example, selected from 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. N-methylpyrrolidone is particularly preferred as component D).

[0050] 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, dimethylsulfoxide and dimethylformamide.

[0051] In particular, it may be preferred that, based on the reaction mixture R MThe total weight of component D) in the present invention is 50% by weight of component D), component D) comprises at least 50% by weight of at least one solvent selected from the group consisting of N-methylpyrrolidone, N-dimethylacetamide, dimethyl sulfoxide and dimethylformamide. N-methylpyrrolidone is particularly preferred as component D). In another preferred embodiment, component D) consists essentially of N-methylpyrrolidone. "Essentially consisting of..." should be understood to mean that component D) contains more than 98% by weight, particularly preferably more than 99% by weight, and more preferably more than 99.5% by weight of at least one aprotic polar solvent, which is selected from the group consisting of N-methylpyrrolidone, N-dimethylacetamide, dimethyl sulfoxide and dimethylformamide, and particularly preferably N-methylpyrrolidone. In a specific embodiment of the present invention, component D) consists of N-methylpyrrolidone. N-methylpyrrolidone is also referred to as NMP or N-methyl-2-pyrrolidone.

[0052] In step I) of the method of the present invention, at a starting temperature T 1 The reaction mixture R M . T 1 It can be, for example, ambient temperature, such as 20°C to 27°C, in particular 20°C to 25°C, such as 21°C, 22°C, 23°C and 24°C. The method is not limited to this T 1 , T 1 It can also be 20℃ to 80℃, or T 1 It can simply be the temperature naturally existing in the environment where the reaction occurs. A more important feature of the method of the present invention is that 1 From the beginning to the final reaction temperature T F The rate of temperature change.

[0053] According to step II) of the process of the invention, the reaction mixture R is heated at a rate of at least 0.4 K / min. M From the starting temperature T 1 Heated to the final reaction temperature T F .

[0054] Therefore, the heating rate characterizing the process according to the invention is at least 0.4 K / min. It may be preferred if the rate is at least 0.45 K / min, more particularly at least 0.5 K / min. According to another specific embodiment of the invention, the rate is at least 0.55 K / min, even more particularly the rate is at least 0.6 K / min. The limit of the rate is given by the capacity of the apparatus in which the reaction takes place, which naturally 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 The upper limit of this temperature depends on the exact reactants and solvents used, and is determined by the boiling point of the at least one aprotic solvent (component D) at standard pressure (1013.25 mbar).F It is usually in the range of 80°C to 250°C, preferably 100°C to 220°C. If T F A temperature T in the range of 130°C to 200°C, in particular 150°C to 195°C, may be preferred. A temperature T of 160°C to 190°C, such as 180°C to 190°C F May be preferred.

[0055] The method according to the invention is usually preferably carried out at standard pressure. F The mixture is preferably kept at this temperature for a time interval of 2 hours to 12 hours, in particular in the range of 3 hours to 10 hours, which time is referred to herein as the "reaction time".

[0056] As mentioned above and generally known to the skilled person, in addition to the desired polymer (P), the product mixture P M Also included in 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.

[0057] In one embodiment, after step II) from the product mixture P M The halides are separated from the mixture, wherein the halides can be separated by any method known to the technician, for example, by filtering or centrifuging. Therefore, the present invention also provides a method, which further comprises the following steps:

[0058] IIIa) filtering the product mixture (P) obtained in step II) M ).

[0059] In step IIIa), the halide is removed, most preferably to obtain a halide-free product mixture (P M ). However, P M Still, traces of halides may be present. In this context, "trace amounts of halides" means the amount of halides present in the product mixture P. M % by weight, preferably less than 0.1 wt. % and most preferably less than 0.01 wt. % of the corresponding halide. After step IIIa), based on the total weight of the product mixture (P M ) of the total weight of the product mixture (P M ) typically contains at least 0.0001 wt %, such as at least 0.0005 wt % or at least 0.001 wt % halide.

[0060] The product mixture (P M The separation of the polyarylene (ether) sulfone polymer (P) in the product mixture (P) can be carried out, for example, by subjecting the product mixture (PM ) is precipitated in water or a mixture of water and other solvents. The precipitated polyarylene (ether) sulfone polymer (P) can then be extracted with water and then dried. In one embodiment of the invention, the precipitate can also be absorbed in an acidic medium. Suitable acids are, for example, organic or inorganic acids, for example carboxylic acids such as acetic acid, propionic acid, succinic acid or citric acid, and inorganic acids such as hydrochloric acid, sulfuric acid or phosphoric acid.

[0061] Therefore, in another embodiment, the present invention also provides a method comprising the following steps:

[0062] IIIb) from the product mixture (P M ) isolating the polyarylene (ether) sulfone polymer (P).

[0063] Step IIIb) is optional and can be performed after step II) or step IIIa) if IIIa) filtration is part of the process.

[0064] In this article, "polymer" may mean a homopolymer or a copolymer or a mixture thereof. Those skilled in the art recognize that any polymer (whose nature may be a homopolymer or a copolymer) is generally a mixture of individual polymers that differ in their composition (such as chain length, degree of branching or nature of end groups). Therefore, in the following, "at least one" as a polymer prefix means that different types of polymers may be covered, whereby each type may have differences in the above composition.

[0065] The polyarylene (ether) sulfone obtained by the process of the present invention is a class of polymers generally known to those skilled in the art. It may be preferred that the polyarylene (ether) sulfone is composed of units of the general formula II

[0066]

[0067] The symbols t, q, Q, T, Y, Ar and Ar 1 is defined as follows:

[0068] t, q are independently 0, 1, 2 or 3;

[0069] Q, T, and Y are independently a chemical bond or selected from -O-, -S-, -SO2-, S=O, C=O, -N=N-, and -CR a R b - a group, wherein R a and R b are independently hydrogen atoms, (C1-C 12 )alkyl, (C1-C 12 ) alkoxy, (C3-C 12 )cycloalkyl or (C6-C 18) aryl group, and wherein at least one of Q, T and Y is present and is -SO2-; and

[0070] Ar and Ar 1 Independently of each other (C6-C 18 ) arylene group.

[0071] Under the above-mentioned prerequisite, if 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 present in a manner of being directly connected to each other via a chemical bond.

[0072] According to a preferred embodiment, t and q are independently 0 or 1.

[0073] According to a preferred embodiment, Q, T and Y in Formula II are independently selected from 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-. In addition, if R a and R b Independently of each other, hydrogen or (C1-C4)alkyl may be preferred.

[0074] In-CR a R b -Middle, R a and R b Preferably independently selected from hydrogen, (C1-C 12 )alkyl, (C1-C 12 ) alkoxy and (C6-C 18 )aryl.

[0075] (C1-C 12 )alkyl refers to a straight-chain or branched saturated hydrocarbon group having 1 to 12 carbon atoms. In particular, the following moieties are contemplated: (C1-C6)alkyl, such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, 2-methylpentyl or 3-methylpentyl, and (C7-C 12 ) alkyl groups such as unbranched heptyl, octyl, nonyl, decyl, undecyl, lauryl, and their singly or multiply branched analogs.

[0076] The term "C1-C 12 "-Alkoxy" refers to a straight-chain or branched alkyl group having 1 to 12 carbon atoms bonded via oxygen at any position of the alkyl group (for example methoxy, ethoxy, n-propoxy, 1-methylethoxy, butoxy, 1-methylpropoxy, 2-methyl-prop-oxy or 1,1-dimethylethoxy).

[0077] (C3-C 12)Cycloalkyl refers to a monocyclic saturated hydrocarbon radical having 3 to 12 carbon ring members and particularly includes (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.

[0078] Ar and Ar 1 Independently of each other (C6-C 18 )-arylene group. It may be preferred that, according to a specific embodiment, Ar 1 For unsubstituted (C6-C 12 ) arylene group.

[0079] It is preferred that Ar and Ar 1 are independently selected from phenylene, biphenylene and naphthylene, and arylene groups derived from anthracene, phenanthrene or naphthacene. 1 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, 2,7-dihydroxynaphthylene and 4,4'-biphenylene.

[0080] In particular, it is preferred that Ar and Ar 1 is independently selected from phenylene groups and naphthylene groups, such as 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 independently selected from 1,4-phenylene, 1,3-phenylene and naphthylene. In addition, according to another embodiment of the present invention, Ar and Ar 1 are independently selected from arylene groups derived from anthracene, phenanthrene or naphthacene. According to yet another embodiment, Ar and Ar 1 Independently selected from 2,7-dihydroxynaphthalene and 4,4'-biphenylene.

[0081] It may be preferred if the polyarylene (ether) sulfone comprises at least one of the following repeating units IIa to IIo:

[0082]

[0083]

[0084] In addition to the units IIa to IIo which may preferably be present, further repeating units are repeating units in which one or more 1,4-phenylene units derived from hydroquinone have been replaced by 1,3-phenylene units derived from resorcinol or by naphthylene units derived from dihydroxynaphthalene.

[0085] Particularly preferred units of the formula II are units IIa, IIg and / or IIk. According to a specific embodiment, it is particularly preferred that the polyarylene (ether) sulfone consists essentially of one type of units of the formula II, wherein the one type can in particular be selected from IIa, IIg and IIk.

[0086] According to a preferred embodiment, the polyarylene (ether) sulfone is composed of repeating units, wherein Ar is 1,4-phenylene, t is 1, q is 0, T is a chemical bond, and Y is SO2. Such polyarylene (ether) sulfone is also known as polyphenylene sulfone (PPSU) (Formula IIg).

[0087] According to a further 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. Such polyarylene (ether) sulfones are also known as polysulfones (PSU) (Formula IIa).

[0088] According to a further 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. Such polyarylene (ether) sulfone is also known as polyether sulfone (PESU) (Formula IIk).

[0089] For the purposes of this disclosure, abbreviations such as PPSU, PESU and PSU conform to DIN EN ISO 1043-1:2001.

[0090] Polyarylene (ether) sulfones generally have halogen end groups, in particular -F or -Cl, or phenolic OH end groups or phenolate end groups, the latter of which may be present as such or in reacted form, in particular in the form of -OCH3 end groups. The amount of phenolic end groups can be determined by potentiometric titration.

[0091] For the purposes of the present invention, the expression "phenol end group" means a hydroxyl group which is bonded to an aromatic ring and optionally also present in deprotonated form. As is known to the person skilled in the art, a phenol end group can also take the form of a so-called phenolate end group as a result of proton cleavage caused by exposure to a base. The expression "phenol end group" therefore explicitly includes not only aromatic OH groups but also phenolate groups.

[0092] 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 toluene / methanol solution of tetrabutylammonium hydroxide. The endpoint is recorded potentiometrically. The proportion of halogen end groups is preferably determined by elemental analysis. 1 H-NMR determines the amount of methoxy groups. These techniques are well known to the skilled person.

[0093] The polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention preferably has a weight average molecular weight (Mw) determined by GPC (gel permeation chromatography) in the range of 15 000 g / mol to 180 000 g / mol, more preferably in the range of 20 000 g / mol to 150 000 g / mol and particularly preferably in the range of 25 000 g / mol to 125 000 g / mol. The GPC analysis was carried out using dimethylacetamide containing 0.5 wt % LiBr as solvent, with a polymer concentration of 4 mg / mL. The system was calibrated with PMMA standards. Three different units based on polyester copolymers were used as columns. After dissolving the material, the resulting solution was filtered using a filter with a pore size of 0.2 μm, and 100 μL of the solution was then injected into the system, with the elution rate set to 1 mL / min. Furthermore, the polyarylene (ether) sulfone polymers (P) obtainable by the process according to the invention preferably have a number average molecular weight (Mn) determined by GPC (gel permeation chromatography) in the range of 5 000 g / mol to 75 000 g / mol, more preferably in the range of 6 000 g / mol to 60 000 g / mol and particularly preferably in the range of 7 500 g / mol to 50 000 g / mol. The GPC analysis is carried out as described above. The glass transition temperature (TG) of the polyarylene (ether) sulfone polymers (P) is generally in the range of 180° C. to 260° C., preferably in the range of 180° C. to 255° C. and particularly preferably in the range of 180° C. to 250° C., determined in the second heating cycle at a heating rate of 10 K / min via differential scanning calorimetry (DSC). The viscosity number (VN) of the polyarylene (ether) sulfone polymers (P) is determined as a 1% solution in N-methylpyrrolidone at 25° C. The viscosity number (VN) is in particular in the range from 65 ml / g to 120 ml / g, typically > 65 ml / g, preferably in the range from 66 ml / g to 100 ml / g and most preferably in the range from 70 ml / g to 90 ml / g.

[0094] Surprisingly, by following the process parameters of the invention as detailed herein, the process of the invention results in very low amounts of cyclic dimers without the need for a subsequent purification step. "Cyclic dimers" are unwanted by-products that may be formed during polycondensation, wherein the linear condensation products of two monomers A) and two monomers B) react under ring closure.

[0095] In particular, the composition comprises the cyclic dimer in an amount of 1.1 wt% or less (0 wt% to 1.1 wt%), specifically 1.0 wt% or less (0 wt% to 1.0 wt%), more specifically 0.9 wt% or less (0 wt% to 0.9 wt%).

[0096] According to one embodiment, the cyclic dimer content is from 0.1% to 1.1% by weight, in particular from 0.2% to 1.1% by weight, more particularly from 0.3% to 1.1% by weight, even more particularly from 0.4% to 1.1% by weight. It may also be preferred if the cyclic dimer content is from 0.5% to 1.1% by weight, in particular from 0.6% to 1.1% by weight, more particularly from 0.7% to 1.1% by weight, even more particularly from 0.8% to 1.1% by weight. A further embodiment relates to a polyarylene (ether) sulfone composition obtainable by the process according to the invention, wherein the cyclic dimer content is from 0.9% to 1.1% by weight, in particular from 1.0% to 1.1% by weight.

[0097] According to a further embodiment, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process according to the invention is from 0.1% to 1.0% by weight, in particular from 0.2% to 1.0% by weight, more particularly from 0.3% to 1.0% by weight, even more particularly from 0.4% to 1.0% by weight. It may also be preferred if the cyclic dimer content is from 0.5% to 1.0% by weight, in particular from 0.6% to 1.0% by weight, more particularly from 0.7% to 1.0% by weight, even more particularly from 0.8% to 1.0% by weight. A further embodiment relates to a polyarylene (ether) sulfone composition obtainable by the process according to the invention, wherein the cyclic dimer content is from 0.9% to 1.0% by weight.

[0098] A further embodiment relates to a polyarylene (ether) sulfone composition obtainable by the process according to the invention, wherein the cyclic dimer content is from 0.1% to 0.9% by weight, in particular from 0.2% to 0.9% by weight, more particularly from 0.3% to 0.9% by weight, even more particularly from 0.4% to 0.9% by weight. It may also be preferred if the cyclic dimer content is from 0.5% to 0.9% by weight, in particular from 0.6% to 0.9% by weight, more particularly from 0.7% to 0.9% by weight, even more particularly from 0.8% to 0.9% by weight.

[0099] According to a further embodiment, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process according to the invention is from 0.1% to 0.8% by weight, in particular from 0.2% to 0.8% by weight, more particularly from 0.3% to 0.8% by weight, even more particularly from 0.4% to 0.8% by weight. It may also be preferred if the cyclic dimer content is from 0.5% to 0.8% by weight, in particular from 0.6% to 0.8% by weight, more particularly from 0.7% to 0.8% by weight.

[0100] According to a further embodiment, the cyclic dimer content in the polyarylene (ether) sulfone composition obtainable by the process according to the invention is from 0.1% to 0.7% by weight, in particular from 0.2% to 0.7% by weight, more particularly from 0.3% to 0.7% by weight, even more particularly from 0.4% to 0.7% by weight. It may also be preferred if the cyclic dimer content is from 0.5% to 0.7% by weight, in particular from 0.6% to 0.7% by weight.

[0101] According to a further embodiment, 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 particularly from 0.3% to 0.6% by weight, even more particularly from 0.4% to 0.6% by weight. It may also be preferred if the cyclic dimer content is from 0.5% to 0.6% by weight.

[0102] 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 wt %, in particular 0.2 to 0.5 wt %, more particularly 0.3 to 0.5 wt %, even more particularly 0.4 to 0.5 wt %.

[0103] 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 wt %, in particular 0.2 to 0.4 wt %, more specifically 0.3 to 0.4 wt %.

[0104] 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 wt %, in particular 0.2 to 0.3 wt %, more specifically 0.1 to 0.2 wt %.

[0105] Furthermore, surprisingly, by using the process of the present invention as described in detail herein, very small amounts of cyclic oligomers other than cyclic dimers are also present in the polymer product produced. This is achieved by the process itself, without subsequent purification steps to remove the oligomers from the reaction product. In general, "cyclic oligomers" are unwanted by-products that may be formed during polycondensation, where linear condensation products of different lengths react under ring closure, e.g., where oligomers from

[0106] - a linear condensation product of three monomers A) and three monomers B) reacted under ring closure (hereinafter "cyclic trimer");

[0107] - a linear condensation product of four monomers A) and four monomers B) reacted under ring closure (hereinafter "cyclic tetramer");

[0108] - a linear condensation product of five monomers A) and five monomers B) reacted under ring closure (hereinafter "cyclic pentamer");

[0109] - a linear condensation product of six monomers A) and six monomers B) reacted under ring closure (hereinafter "cyclic hexamer");

[0110] - a linear condensation product of seven monomers A) and seven monomers B) reacted under ring closure (hereinafter "cyclic heptamer");

[0111] - a linear condensation product of eight monomers A) and eight monomers B) reacted under ring closure (hereinafter "cyclic octamer");

[0112] - a linear condensation product of nine monomers A) and nine monomers B) reacted under ring closure (hereinafter "cyclic nonamer"); and / or

[0113] - A linear condensation product of ten monomers A) and ten monomers B) reacted under ring closure (hereinafter "cyclic decamer").

[0114] Each of the cyclic oligomers is preferably contained independently in the inventive polymer obtained by the process of the invention in an amount of less than or equal to 1.1% by weight (0% to 1.1% by weight), in particular less than or equal to 1.0% by weight (0% to 1.0% by weight), more particularly less than or equal to 0.9% by weight (0% to 0.9% by weight). The preferred ranges given above for the cyclic dimer apply independently to each of the cyclic oligomers (trimer, tetramer, pentamer, hexamer, heptamer, octamer, nonamer, decamer).

[0115] The content of cyclic oligomers can be measured, for example, by size exclusion chromatography, which is well known to the skilled person. Individual cyclic oligomers can be identified, for example, by Maldi-TOF mass spectrometry. Cyclic oligomers do not have end groups and are therefore distinguishable from linear oligomers which also have low molecular weights compared to the desired polymer product.

[0116] Furthermore, it is surprising that the process parameters according to the invention lead to polyarylene (ether) sulfone polymers (P) having a very low content of aromatic volatiles without subsequent purification steps to remove aromatic volatiles from the reaction product. "Aromatic volatiles" to be avoided as contaminants in polyarylene (ether) sulfone polymers (P) are, for example, selected from toluene, ethylbenzene, o-xylene, m-xylene, p-xylene and chlorobenzene.

[0117] The product of the process of the present invention preferably comprises less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, still more specifically less than 20 ppm of each of the aromatic volatiles detailed above, based on the total weight of the polymer product, wherein these amounts apply independently to each of the volatiles. More preferably, the product of the process of the present invention preferably comprises less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, yet more specifically less than 3 ppm of each of the aromatic volatiles detailed above, based on the total weight of the polymer product, wherein these amounts apply independently to each of the volatiles.

[0118] In a very specific embodiment, the product of the process of the present invention preferably comprises less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, still more specifically less than 20 ppm of the aromatic volatiles detailed above. More preferably, the product of the process of the present invention preferably comprises less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, still more specifically less than 3 ppm of the aromatic volatiles detailed above.

[0119] According to one embodiment, the product of the process of the present invention preferably contains less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, still more specifically less than 20 ppm of chlorobenzene, based on the total weight of the polymer product. More preferably, the product of the process of the present invention preferably contains less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, still more specifically less than 3 ppm of chlorobenzene, based on the total weight of the polymer product.

[0120] According to another embodiment, the product of the inventive process preferably contains less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, and still more specifically less than 20 ppm of toluene, based on the total weight of the polymer product. More preferably, the product of the inventive process preferably contains less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, and still more specifically less than 3 ppm of toluene, based on the total weight of the polymer product.

[0121] According to another embodiment, the product of the process of the present invention preferably contains less than 100 ppm, more preferably less than 50 ppm, even more specifically less than 30 ppm, and still 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 preferably contains less than 15 ppm, more preferably less than 10 ppm, even more specifically less than 5 ppm, and still more specifically less than 3 ppm of chlorobenzene and toluene, based on the total weight of the polymer product.

[0122] In particular, the polyarylene (ether) sulfone composition obtainable by the process of the invention is substantially free of chlorobenzene. In another embodiment, the polyarylene (ether) sulfone composition obtainable by the process of the invention is substantially free of toluene. According to another embodiment, the polyarylene (ether) sulfone composition obtainable by the process of the invention is substantially free of toluene and chlorobenzene. According to another embodiment, the polyarylene (ether) sulfone composition obtainable by the process of the invention is substantially free of aromatic volatiles, in particular as defined above. In this context, the term "substantially free" is understood to mean that the product may contain only negligible traces of the corresponding aromatic volatiles.

[0123] Furthermore, it is preferred that the polyarylene (ether) sulfone does not contain chlorobenzene. Furthermore, it is preferred that the polyarylene (ether) sulfone does not contain toluene, and it is even more preferred if the polyarylene (ether) sulfone does not contain chlorobenzene or toluene. It is particularly preferred if the polyarylene (ether) sulfone does not contain any of the aromatic volatile substances listed above.

[0124] Therefore, another object of the present invention is a polyarylene (ether) sulfone composition obtainable by the process of the present invention as described herein. In particular, the polyarylene (ether) sulfone of the present invention has a high molecular weight as defined and preferably defined above (e.g. VN> 65 ml / g), a cyclic dimer content as defined and preferably defined above and a low content of aromatic volatiles (such as chlorobenzene) as detailed above (including preferred embodiments).

[0125] Another advantage of the process of the present invention is that it produces a first polyarylene (ether) sulfone polymer (P) having a high purity, which purity can be measured by the turbidity of the polymer product. Methods for measuring turbidity are well known to the skilled person.

[0126] The purity of the product can be characterized, for example, by turbidity measurement using a Hach TL2360 photometer using a DMF solution containing 20% ​​by weight of the polymer. The device is internally calibrated and the results are given in "NTU" (nephelometric turbidity units) in the range of 0 to 40 N.TU. The solution is preferably prepared and then allowed to equilibrate for 24 h before the measurement is performed. Then, after the solution has been stored for a period of time, for example after 7 days in the dark, a second measurement can be performed. The result of this second measurement is particularly meaningful for determining whether the polymer is suitable for industrial applications (e.g. for the production of membranes).

[0127] According to a preferred embodiment of the present invention, the polyarylene (ether) sulfone polymer (P) obtained by the method of the present invention shows a turbidity of 0 to 1.75, preferably 0 to 1.74 after 24 hours using a Hach TL2360 photometer and the above method. In addition, according to another preferred embodiment, the polyarylene (ether) sulfone polymer (P) obtained by the method of the present invention shows a turbidity of 0 to 1.95, preferably 0 to 1.90 after 7 days using a Hach TL2360 photometer and the above method. According to another preferred embodiment, the turbidity measured for the first time (24 hours) and the second time (7 days) using a Hach TL2360 photometer and the above method is 0 to 1.95, preferably 0 to 1.90.

[0128] The low turbidity makes the product very suitable for use in membranes. The specific process parameters of the process of the invention produce polymers with favorable turbidity values ​​without the need to remove such impurities in a subsequent purification step.

[0129] As mentioned above, the polyarylene (ether) sulfones according to the invention are very suitable for use in membrane production processes, in particular in the case of membrane production from solution, especially due to their low content of cyclic dimers and aromatic volatiles and their advantageous purity.

[0130] The skilled person is familiar with the preparation of membranes. It is known that during the preparation of membranes, solvent exchange generally results in an asymmetric membrane structure. Therefore, the membrane is preferably asymmetric. In an asymmetric membrane, the pore size increases from the top layer used for separation to the bottom of the membrane.

[0131] If the membrane is a porous membrane, the membrane generally comprises pores. The pores are generally measured by filtration experiments using solutions containing different PEGs with molecular weights of 300 g / mol to 1000000 g / mol, and the diameters in the range of 1 nm to 10000 nm, preferably in the range of 2 nm to 500 nm and particularly preferably in the range of 5 nm to 250 nm. By comparing the GPC-traces of the feed and the filtrate, the retention of each molecular weight of the membrane can be determined. Under given conditions, the molecular weight at which the membrane shows 90% retention is considered to be the molecular weight cutoff (MWCO) of the membrane. Using the known correlation between the Stokes diameter of PEG and their molecular weights, the average pore size of the membrane can be determined. Details about this method are given in the literature (Chung, J.Membr.Sci.531 (2017) 27-37). If the membrane is prepared via a phase inversion method, a porous membrane is generally obtained.

[0132] Dense membranes generally contain virtually no pores. Dense membranes are generally obtained by a solution casting process in which the solvent contained in the casting solution is evaporated. The separation layer (the solution from which the membrane is obtained after separation of the solvent) is generally cast on a support which may be another polymer such as polysulfone or cellulose acetate. A polydimethylsiloxane layer is sometimes applied on top of the separation layer.

[0133] The membrane can have any thickness. For example, the thickness of the membrane is in the range of 2 μm to 150 μm, preferably in the range of 3 μm to 100 μm and most preferably in the range of 5 μm to 60 μm. The membrane of the present invention can be used in any method of using membranes known to the skilled person. In particular, if the membrane is a dense membrane, it is particularly suitable for gas separation.

[0134] An object of the present invention is therefore the use of the polyarylene (ether) sulfone polymer (P) or the polyarylene (ether) sulfone polymer (P) composition obtainable by the process of the present invention in membranes.

[0135] According to one embodiment of the present invention, the polyarylene (ether) sulfone polymer (P) of the present invention is used in an asymmetric membrane. In another embodiment, the membrane is porous.

[0136] In another embodiment of the present invention the polyarylene (ether) sulfone polymer (P) is used in a dense membrane. Therefore, another object of the present invention is also a membrane, wherein the membrane is a dense membrane.

[0137] Another object of the present invention is also the use of the polyarylene ether (sulfone) polymers (P) obtainable by the process according to the invention for the production of membranes, wherein the production comprises a phase inversion from a solution.

[0138] If the membrane is a porous membrane, the membrane is particularly suitable for nanofiltration, microfiltration and / or ultrafiltration. Typical nanofiltration, ultrafiltration and microfiltration methods are known to the skilled person. For example, the membrane can be used as a dialysis membrane during dialysis. The polyarylene (ether) sulfone polymers (P) obtainable by the method of the present invention are particularly suitable for the manufacture of dialysis membranes.

[0139] Therefore, 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 membranes, in particular 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 ultrafiltration membranes, such as dialysis membranes. According to another embodiment, the polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention is used for the manufacture of gas separation membranes.

[0140] Another object of the present invention is a membrane comprising a polyarylene (ether) sulfone polymer (P) obtainable by the inventive process as described herein. In particular, the membrane is a nanofiltration membrane, an ultrafiltration membrane and / or a microfiltration membrane, more particularly an ultrafiltration membrane. According to another embodiment, the membrane comprising a polyarylene (ether) sulfone polymer (P) obtainable by the inventive process as described herein is a gas separation membrane.

[0141] Membranes can be prepared from the polyarylene (ether) sulfone polymers (P) obtained according to the invention by any method known to the skilled person.

[0142] Another object of the present invention is a process for preparing a membrane comprising a polyarylene (ether) sulfone polymer (P) obtainable by the process of the present invention, comprising the following steps:

[0143] i) providing a solution comprising a polyarylene (ether) sulfone polymer (P) and at least one solvent;

[0144] ii) separating at least one solvent from the solution to obtain a membrane.

[0145] The at least one solvent in step i) can be just one solvent, or it can also be a mixture of two or more solvents. The solution in step i) can be provided by any method known to the skilled person, for example in a conventional container which may include a stirring device and preferably a temperature control device. Preferably, the solution is provided by dissolving the polyarylene (ether) sulfone polymer (P) in at least one solvent, preferably under stirring. Step i) is preferably carried out at an elevated temperature, especially in the range of 20°C to 120°C, more preferably in the range of 40°C to 100°C. The skilled person will select the temperature according to the at least one solvent. The solution preferably comprises 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) is preferably not separable from at least one solvent by filtration. Based on the total weight of the solution, the solution preferably comprises 0.001 wt.% to 50 wt.% of the polyarylene (ether) sulfone polymer (P). More preferably, based on the total weight of the solution, the solution in step i) comprises 0.1 wt % to 30 wt % of polyarylene (ether) sulfone polymer (P), and most preferably, the solution comprises 0.5 wt % to 25 wt % of polyarylene (ether) sulfone polymer (P). As at least one solvent, any solvent known to the technician for polyarylene (ether) sulfone polymer (P) is suitable. Preferably, the at least one solvent is soluble in water. Therefore, the at least one solvent is preferably selected from the group consisting of N-methylpyrrolidone, dimethylacetamide, dimethyl sulfoxide, dimethyl lactamide, dimethylformamide and cyclopentane sulfone. Particularly preferred are N-methylpyrrolidone and dimethyl lactamide. Dimethyl lactamide is most preferably used as the at least one solvent. Based on the total weight of the solution, the solution preferably comprises at least one solvent in the range of 50 wt % to 99.999 wt %, more preferably in the range of 70 wt % to 99.9 wt % and most preferably in the range of 75 wt % to 99.5 wt %.

[0146] The solution provided in step i) may furthermore comprise additives for membrane preparation.

[0147] Suitable additives for membrane preparation are known to the technician and are, for example, polyvinyl pyrrolidone (PVP), polyethylene oxide (PEO), polyethylene oxide-polypropylene oxide copolymers (PEO-PPO) and poly (tetrahydrofuran) (poly-THF). Polyvinyl pyrrolidone (PVP) and polyethylene oxide (PEO) are particularly preferred as additives for membrane preparation. The additive for membrane preparation can be included in the solution, for example, in an amount of 0.01 wt % to 20 wt %, preferably in a range of 0.1 wt % to 15 wt % and more preferably in a range of 1 wt % to 10 wt %, based on the total weight of the solution. It is clear to a person skilled in the art that the weight percentages of the polyarylene (ether) sulfone polymer (P), at least one solvent and the additives optionally included for membrane preparation generally add up to 100 wt %.

[0148] The duration of step i) can vary within wide limits. The duration of step i) is preferably in the range of 10 min to 48 h (hours), especially in the range of 10 min to 24 h and more preferably in the range of 15 min to 12 h. A person skilled in the art will select the duration of step i) so as to obtain a homogeneous solution.

[0149] In step ii), at least one solvent is separated from the solution to obtain a membrane. The solution provided in step i) may be filtered before separating at least one solvent from the solution in step ii) to obtain a filtered solution. The following embodiments and preferred requirements for separating at least one solvent from the solution are also applicable to separating at least one solvent from the filtered solution used in this embodiment of the present invention. Separating at least one solvent from the solution can be carried out by any method known to the technician that is suitable for separating solvents from polymers. Preferably, separation is carried out via a phase inversion method. If the separation of at least one solvent is carried out via a phase inversion method, the membrane obtained is generally a porous membrane. In the context of the present invention, a phase inversion method means a method in which a dissolved polyarylene (ether) sulfone polymer (P) is converted into a solid phase. Therefore, a phase inversion method can also be expressed as a precipitation method. Suitable phase inversion methods are known to those skilled in the art. The phase inversion method can be carried out, for example, by cooling the solution, wherein the polyarylene (ether) sulfone polymer (P) contained in the solution is precipitated. Another possibility for carrying out a phase inversion method is to contact the solution with a gaseous liquid that is a non-solvent for the polyarylene (ether) sulfone polymer (P). Then the polyarylene (ether) sulfone polymer (P) will also precipitate. Suitable gaseous liquids as non-solvents for polyarylene (ether) sulfone polymers (P) are, for example, gaseous protic polar solvents described below. Another preferred phase inversion method in the context of the present invention is the phase inversion performed by immersing the solution in at least one protic polar solvent. Therefore, in one embodiment of the present invention, in step ii), at least one solvent contained in the solution is separated from the polyarylene (ether) sulfone polymer (P) by immersing the solution in at least one protic polar solvent. This results in the formation of a membrane. Suitable at least one protic polar solvent is known to the technician. At least one protic polar solvent is preferably a non-solvent for polyarylene (ether) sulfone polymers (P). Preferred at least one protic polar solvent is water, methanol, ethanol, n-propanol, isopropanol, glycerol, ethylene glycol and mixtures thereof. Step ii) generally includes providing a solution in the form corresponding to the membrane obtained in step ii). Therefore, in one embodiment of the present invention, step ii) comprises casting the solution to obtain a thin layer of the solution or passing the solution through at least one spinneret to obtain at least one hollow fiber of the solution. Therefore, in a preferred embodiment of the present invention, step ii) comprises the following steps:

[0150] ii-1) casting the solution provided in step i) to obtain a thin layer of the solution,

[0151] ii-2) evaporating at least one solvent from the thin layer of the solution obtained in step ii-1) to obtain a film in the form of a thin layer.

[0152] This means that the film is formed by evaporating at least one solvent from a thin layer of the solution. In step ii-1), the solution can be cast by any method known to the technician. Typically, the solution is cast with a casting knife heated to a temperature in the range of 20°C to 150°C, preferably in the range of 40°C to 100°C. The solution is typically cast on 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 the technician and are, for example, selected from glass plates and polymer fabrics (such as nonwoven materials). In order to obtain a dense membrane, the separation in step ii) is typically carried out by evaporating at least one solvent contained in the solution.

[0153] The obtained membrane preferably comprises at least 50 wt.-% polyarylene (ether) sulfone polymer (P), more preferably at least 70 wt.-% and most preferably at least 90 wt.-% polyarylene (ether) sulfone polymer (P), based on the total weight of the membrane. In another preferred embodiment, the membrane consists essentially of polyarylene (ether) sulfone polymer (P). "Essentially consisting of" means that the membrane comprises more than 95 wt.-%, preferably more than 97.5 wt.-% and most preferably more than 98 wt.-% polyarylene (ether) sulfone polymer (P), based on the total weight of the membrane.

[0154] During the formation of the membrane, the polyarylene (ether) sulfone polymer (P) is separated from at least one solvent. Thus, the membrane obtained is substantially free of at least one solvent. In the context of the present invention, "substantially free" means that the membrane comprises 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 comprises 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.

[0155] The embodiments and preferences given for the polyarylene (ether) sulfone polymers (P) obtainable by the process according to the invention therefore also apply independently to the polyarylene (ether) sulfone polymers (P) used in membranes. Example:

[0156] The following examples provide further explanation of the present invention but do not limit it.

[0157] The viscosity number of the resulting polyaryl(ether)sulfone is obtained by measurement in N-methylpyrrolidone (1 g in 100 ml of solution; 25° C.) according to ISO 1628 standard.

[0158] The content of cyclic oligomers was determined by size exclusion chromatography using tetrahydrofuran (THF) as solvent. Two 30 cm long columns were used for separation. The first column was 100 μl of 1 ... The second column was filled with PLgel Filling. Separation was carried out at 30° C. and a flow rate of 1 ml / min. For detection, a UV detector operating at 254 nm was used. For detection of circulation in polyethersulfone, dichloromethane was used as solvent.

[0159] The purity of the product was further characterized by turbidity measurements using a Hach TL2360 photometer using a DMF solution containing 20% ​​by weight of the polymer. The instrument is internally calibrated and the results are given in "NTU" (nephelometric turbidity units) in the range of 0 to 40 N.TU with an accuracy of + / - 2%. The solution was prepared and then allowed to equilibrate for 24 h before the measurement was made. The solution was then stored in the dark for 7 days and the measurement was then repeated.

[0160] The content of chlorobenzene was determined by GC-analysis. For this purpose, 0.250 g of polymer was added to 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 h and the gas phase was analyzed using a GC system with a DBWAX-column and a FID-detector.

[0161] Example C1

[0162] In a 4-liter glass reactor equipped with a thermometer, an inlet tube and a Dean-Stark separator, 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 having a volume average particle size of 33 μm were suspended in 1000 ml of NMP at 23° C. in a nitrogen atmosphere.

[0163] The mixture was heated to 190° C. within 270 minutes. In the following, the reaction time is understood to be the time during which the reaction mixture was kept at 190° C. The water formed in the reaction was removed continuously by distillation, and the evaporated NMP was replaced.

[0164] After a reaction time of 7 hours, the reaction was stopped by adding 1400 ml of NMP and cooling to 130° C. (within one hour). 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 polymer solution obtained was then precipitated in water, the resulting polymer beads were isolated and then extracted with hot water (85° C.) for 20 h. The beads were then dried at 120° C. for 24 h under reduced pressure (<100 mbar).

[0165] Details of the reaction conditions for all other experiments are summarized in Table 1. C1, C2, C5 and C8 are comparative examples that do not use the combination of process parameters discovered according to the present invention.

[0166] Table 1 :

[0167]

[0168] Materials prepared according to the claimed conditions show a unique combination of properties, such as high VN, low dimer content, excellent purity as shown by turbidity measurements, and are free of chlorobenzene. (C9 = Material: Udel P-3500 LCD, commercially available from Solvay)

Claims

1. A method for preparing a polyarylene (ether) sulfone polymer (P), comprising the following steps: I) At the starting temperature T 1 The reaction mixture R M , the reaction mixture comprises A) at least one aromatic dihalosulfone; B) at least one dihydroxy component; C) at least one carbonate component in excess of at least 3 mol % relative to the dihydroxy component B); D) at least one aprotic solvent; wherein the reaction mixture R M The initial concentration of each of the monomers A) and B) in the mixture is 2.2 mol to 2.7 mol per liter of the at least one aprotic solvent D); and II) the reaction mixture R is heated at a rate of at least 0.4 K / min. M From the starting temperature T 1 Heated to the final reaction temperature T F , whereby a product mixture P is obtained M .

2. The process according to claim 1, wherein A) is at least one dihalogenated diphenyl sulfone.

3. The process according to claim 1 or 2, wherein the at least one dihydroxy component B) is selected from dihydroxybiphenyls, diphenylpropanes and diphenylsulfones.

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

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

6. Use of the polyarylene (ether) sulfone polymer (P) obtainable by the process according to any one of claims 1 to 4 in the manufacture of membranes.

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

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

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

10. A polyarylene (ether) sulfone obtainable by the process according to any one of claims 1 to 4.

11. The polyarylene (ether) sulfone according to claim 10, having a viscosity number of >65 ml / g and a cyclic dimer content equal to or lower than 1.1 wt.%.

12. The polyarylene (ether) sulfone according to claim 10 or 11, comprising chlorobenzene in an amount of less than or equal to 100 ppm.

13. The polyarylene (ether) sulfone according to any one of claims 10 to 12, which shows a turbidity of 0 to 1.75, preferably 1.74 NTU after 24 hours using a Hach TL2360 photometer.

14. The polyarylene (ether) sulfone according to any one of claims 10 to 13, wherein the turbidity after 24 hours and the turbidity after 7 days are 0 to 1.95, preferably 0 to 1.90 NTU using a Hach TL2360 photometer.

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