The use of at least one recycled polyarylene ether sulfone polymer in a method for the preparation of a membrane

Abstract

The present invention relates to the use of at least one recycled polyarylene ether sulfone polymer (rP) in a method for the preparation of a membrane (M), the membrane (M) comprising the at least one recycled polyarylene ether sulfone polymer (rP), wherein the method comprises the steps a) to d): a) providing a first solution (S1) which comprises the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A) and at least one solvent (D), b) filtering the first solution (S1) to obtain a filtered solution (fS), c) adding at least one water soluble additive (C) to the filtered solution (fS) obtained in step b) to obtain a second solution (S2) comprising the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A), at least one solvent (D), and the at least one water soluble additive (C), d) separating the at least one water soluble additive (C) and the at least one solvent (D) from the second solution (S2) obtained in step c) to obtain the membrane (M), wherein the recycled polyarylene ether sulfone polymer (rP) has a weight-average molecular weight (MW) of from 40 000 to 70 000 g / mol.

Description

[0001] 231351

[0002] The use of at least one recycled polyarylene ether sulfone polymer in a method for the preparation of a membrane

[0003] Description

[0004] The present invention relates to the use of at least one recycled polyarylene ether sulfone polymer (rP) in a method for the preparation of a membrane (M), the membrane (M) comprising the at least one recycled polyarylene ether sulfone polymer (rP), wherein the method comprises the steps a) to d): a) providing a first solution (S1) which comprises the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A) and at least one solvent (D), b) filtering the first solution (S1) to obtain a filtered solution (fS), c) adding at least one water soluble additive (C) to the filtered solution (fS) obtained in step b) to obtain a second solution (S2) comprising the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A), at least one solvent (D), and the at least one water soluble additive (C), d) separating the at least one water soluble additive (C) and the at least one solvent (D) from the second solution (S2) obtained in step c) to obtain the membrane (M), wherein the recycled polyarylene ether sulfone polymer (rP) has a weight-average molecular weight (Mw) of from 40000 to 70000 g / mol.

[0005] Polyarylene ether sulfone polymers such as poly (ether sulfone) (PESU) and polysulfone (PSU) have wide application as high performance polymeric materials especially for hemodialysis membranes (M. Vdlkel, N. Herz, Kunststoffe International 2010, 100, 109-111). The polyarylene ether sulfone polymers are spun to dialysis fibers which are then bundled to fiber packages and processed to dialyzer modules. Before the potting of the modules, protruding fibers were cut and cause the accumulation of fiber waste. Currently, these fiber clippings were disposed by incineration which causes additional costs for the dialyzer manufacturers. For the development of cost efficient and environmentally friendly production processes methods for the recycling of polyarylene ether sulfone polymer fiber clippings are required.

[0006] It is therefore an object of the present invention to provide a method which allows the recycling of the polyarylene ether sulfone polymer fiber clippings from dialyzer fabrication.

[0007] This object is achieved by the use of

[0008] (A) at least one recycled polyarylene ether sulfone polymer (rP)

[0009] in a method for the preparation of a membrane (M), the membrane (M) comprising the at least one recycled polyarylene ether sulfone polymer (rP),

[0010] wherein the method comprises the steps a) to d)231351

[0011] 2

[0012] a) providing a first solution (S1) which comprises the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A) and at least one solvent (D),

[0013] b) filtering the first solution (S1) to obtain a filtered solution (fS),

[0014] c) adding at least one water soluble additive (C) to the filtered solution (fS) obtained in step b) to obtain a second solution (S2) comprising the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A), at least one solvent (D), and the at least one water soluble additive (C),

[0015] d) separating the at least one water soluble additive (C) and the at least one solvent (D) from the second solution (S2) obtained in step c) to obtain the membrane (M),

[0016] wherein the recycled polyarylene ether sulfone polymer (rP) has a weight-average molecular weight (Mw) of from 40 000 to 70000 g / mol.

[0017] It has surprisingly been found that, by the inventive use of at least one recycled polyarylene ether sulfone polymer (rP) in a method for the preparation of a membrane (M), a membrane (M) is obtained which can be successfully used for technical filtration applications or for carbon capture storage applications.

[0018] The at least one recycled polyarylene ether sulfone polymer (rP) can easily be processed by non-solvent induced phase separation processes to porous flat sheet or hollow fiber membranes. The membranes based on the at least one recycled polyarylene ether sulfone polymer (rP) have comparable properties to membranes produced from virgin polyarylene ether sulfone polymers.

[0019] In addition, the use of the at least one recycled polyarylene ether sulfone polymer (rP) according to the present invention in a method for the preparation of a membrane (M) renders the dialyzer fabrication process more cost efficient and environmentally friendly.

[0020] The present invention will be described in more detail hereinafter.

[0021] At least one recycled polyarylene ether sulfone polymer (rP) is used in a method for the preparation of a membrane (M), the membrane (M) comprising the at least one recycled polyarylene ether sulfone polymer (rP).

[0022] Method for the preparation of the membrane (M)

[0023] The method for the preparation of the membrane (M) comprises the steps a) to d), wherein step b) is preferably carried out after step a), step c) is preferably carried out after step b), and step d) is preferably carried out after step c).231351

[0024] 3

[0025] Step a)

[0026] In step a), a first solution (S1) which comprises the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A) and at least one solvent (D) is provided.

[0027] The first solution (S1) can be provided in step a) by any method known to the skilled person. For example, the first solution (S1) can be provided in step a) in customary vessels which may comprise a stirring device and preferably a temperature control device. Preferably, the first solution (S1) is provided by dissolving the at least one recycled polyarylene ether sulfone polymer (rP) in the at least one solvent (D).

[0028] The dissolution of the at least one recycled polyarylene ether sulfone polymer (rP) in the at least one solvent (D) to provide the first solution (S1) is preferably carried out under agitation.

[0029] Step a) is preferably carried out at elevated temperatures, especially in the range from 20 to 120 °C, more preferably in the range from 40 to 100 °C. A person skilled in the art will choose the temperature in accordance with the at least one solvent (D).

[0030] The first solution (S1) preferably comprises the at least one recycled polyarylene ether sulfone polymer (rP) completely dissolved in the at least one solvent (D). This means that the first solution (S1) preferably comprises no solid particles of the at least one recycled polyarylene ether sulfone polymer (rP).

[0031] The first solution (S1) preferably comprises from 0.001 to 50 % by weight of the at least one recycled polyarylene ether sulfone polymer (rP) based on the total weight of the first solution (S1). More preferably, the first solution (S1) in step a) comprises from 0.1 to 30 % by weight of the at least one recycled polyarylene ether sulfone polymer (rP) and most preferably the first solution (S1) comprises from 0.5 to 25 % by weight of the at least one recycled polyarylene ether sulfone polymer (rP) based on the total weight of the first solution (S1).

[0032] Component (A) / At least one recycled polyarylene ether sulfone polymer (rP)

[0033] The first solution (S1) comprises at least one recycled polyarylene ether sulfone polymer (rP). "At least one recycled polyarylene ether sulfone polymer (rP)”, according to the invention, is understood to mean exactly one recycled polyarylene ether sulfone polymer (rP) and also mixtures of two or more recycled polyarylene ether sulfone polymers (rP).

[0034] In the context of the present invention, the term "recycled” means that the polyarylene ether sulfone polymer is waste from another process, wherein the polyarylene ether sulfone polymer is not thrown away as trash but turned into a new product. Preferably, the at least one recycled polyarylene ether sulfone polymer (rP) is obtained by processing polyarylene ether sulfone polymer fibre waste from dialyzer fabrication into granulate.231351

[0035] 4

[0036] Therefore, another object of the present invention is a use wherein the at least one recycled polyarylene ether sulfone polymer (rP) is obtained by processing polyarylene ether sulfone polymer fibre waste from dialyzer fabrication into granulate.

[0037] The at least one recycled polyarylene ether sulfone polymer (rP) has a weight-average molecular weight (Mw) of from 40000 to 70000 g / mol. The weight average molecular weight (Mw) is measured using gel permeation chromatography (GPC). Tetrahydrofuran (THF) was used as solvent and narrowly distributed polystyrene was used as standard in the measurement.

[0038] Preferably, the weight average molecular weight (Mw) of the at least one recycled polyarylene ether sulfone polymer (rP) used in the method of the present invention is in the range from 45000 to 70000 g / mol, more preferably in the range from 50000 to 70000 g / mol.

[0039] In addition, the at least one recycled polyarylene ether sulfone polymer (rP) preferably has a polydispersity MW / MN in the range from 2 to 4. The polydispersity is defined as the quotient of the weight average molecular weight (Mw) and the number average molecular weight (MN). The number average molecular weight (MN) is also measured by means of gel permeation chromatography.

[0040] Therefore, another object of the present invention is a use wherein the at least one recycled polyarylene ether sulfone polymer (rP) has a polydispersity in the range of from 2 to 4.

[0041] The at least one recycled polyarylene ether sulfone polymer (rP) preferably has a glass transition temperature (TG(PP)) in the range of from 180 to 190 °C.

[0042] The measurement of the glass transition temperature TG(PP) is carried out in a differential scanning calorimeter DSC 2000 (TA Instruments) at a heating rate of 10 K / min. For the measurement, approximately 5 mg of the substance are sealed in an aluminum crucible. In the first heating run, the samples are heated to 280°C, then rapidly cooled to -100°C and then, in the second heating run, heated to 280°C at 10 K / min. The respective TG(PP) value is determined from the second heating run.

[0043] Therefore, another object of the present invention is a use wherein the at least one recycled polyarylene ether sulfone polymer (rP) has a glass transition temperature (TG(PP)) in the range of from 180 to 190 °C.

[0044] The at least one recycled polyarylene ether sulfone polymer (rP) preferably used in the method according to the present invention preferably has a viscosity number of 60 ml / g to 85 ml / g. This viscosity number is quantified according to DIN EN ISO 1628-5 (1998) in a 1 wt.-% solution of N-methylpyrrolidone (NMP) at 25°C.231351

[0045] 5

[0046] Therefore, another object of the present invention is a use wherein the at least one recycled polyarylene ether sulfone polymer (rP) has a viscosity number in the range of from 60 to 85 ml / g.

[0047] Especially preferred as component (A) are recycled polyarylene ether sulfone polymers (rP) selected from the group consisting of recycled polyethersulfone (rPESU), recycled polyphenylensulfone (rPPSU) and recycled polysulfone (rPSU), wherein recycled polysulfone (rPSU) is particularly preferred.

[0048] Therefore, another object of the present invention is a use wherein the at least one recycled polyarylene ether sulfone polymer (rP) is a recycled polysulfone (rPSU).

[0049] The abbreviations PPSU, PESU and PSU in the present case are in accordance with DIN EN ISO 1043-1 :2001.

[0050] In case the recycled polyarylene ether sulfone polymer (rP) or the polyarylene ether sulfone polymer fibre waste, respectively, originates from a porous polyarylene ether sulfone polymer membrane, the at least one recycled polyarylene ether sulfone polymer (rP) can comprise poly (vinyl pyrrolidone). Preferably, the at least one recycled polyarylene ether sulfone polymer (rP) comprises in the range of from 1 to 10 wt% of poly(vinyl pyrrolidone).

[0051] Therefore, another object of the present invention is a use wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprises in the range of from 1 to 10 wt% of poly(vinyl pyrrolidone).

[0052] The poly (vinyl pyrrolidone) can be used as pore forming additive in the preparation process of a porous polyarylene ether sulfone polymer membrane. The method for the preparation of the porous polyarylene ether sulfone polymer membrane then preferably comprises the steps

[0053] i) providing a solution (MS) which comprises the polyarylene ether sulfone polymer, at least one pore forming additive and at least one solvent,

[0054] ii) separating the at least one pore forming additive and the at least one solvent from the solution (MS) at least partly to obtain the porous polyarylene ether sulfone polymer membrane.

[0055] The term "at least partly” within the context of the present invention means that preferably at least 50% by weight, more preferably at least 60% by weight, of the polyarylene ether sulfone polymer, based on the total weight of the polyarylene ether sulfone polymer comprised in the solution (MS), are separated from the at least one pore forming additive and the at least one solvent.

[0056] Processes for the preparation of the polyarylene ether sulfone polymer are known to the skilled person. In a preferred embodiment the polyarylene ether sulfone polymer is prepared by a process comprising the step of converting a reaction mixture (RG) comprising as components at least one aromatic dihalogen sulfone, at least one aromatic231351

[0057] 6

[0058] dihydroxy compound, at least one carbonate compound and at least one aprotic polar solvent. Preferably, the polyarylene ether sulfone polymer is non-sulfonated.

[0059] "Non-sulfonated” within the context of the present invention means that the non-sulfonated polyarylene ether sulfone polymer does not comprise any groups resulting from the sulfonation of the aromatic dihalogen sulfone contained in the non-sulfonated polyarylene ether sulfone polymer. Processes for the sulfonation are known to the skilled person. In particular, "non-sulfonated” within the context of the present invention means that the non-sulfonated polyarylene ether sulfone polymer does not comprise any -SO2X group wherein X is selected from the group consisting of OH and 0- combined with one cation equivalent.

[0060] Component (D) / Solvent

[0061] The first solution (S1) comprises at least one solvent as component (D). "At least one solvent”, according to the invention, is understood to mean exactly one solvent and also mixtures of two or more solvents.

[0062] Preferably, the at least one solvent (D) is at least one protic or aprotic polar solvent (D), more preferably the at least one solvent (D) is soluble in water.

[0063] Suitable aprotic polar solvents are, for example, selected from the group consisting of N-methylpyrrolidone, N-butylpyrrolidone, N-tert-butylpyrrolidone, N-(2'-hydroxyethyl)-2-pyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, N, N-dimethyllactamide, gamma-valerolactone, dihydrolevoglucosenone, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, methyl-1-methyl-2-oxopyrrolidone -4-carboxylate, 2-(2-oxopyrrolidin-1-yljethyl acetate and sulfolane.

[0064] N,N-dimethylacetamide is particularly preferred as component (D).

[0065] Another object of the present invention is therefore also a use wherein the at least one solvent (D) is selected from the group consisting of N-methylpyrrolidone, N-butylpyrrolidone, N-tert-butylpyrrolidone, N-(2'-hydroxyethyl)-2-pyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, N, N-dimethyllactamide, gamma-valerolactone, dihydrolevoglucosenone, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, methyl-1-methyl-2-oxopyrrolidone -4-carboxylate, 2-(2-oxopyrrolidin-1 -yljethyl acetate and sulfolane, preferably N,N-dimethylacetamide.

[0066] It is preferred that component (D) comprises at least 50 % by weight of at least one solvent selected from the group consisting of N-methylpyrrolidone, N-butylpyrrolidone, N-tert-butylpyrrolidone, N-(2'-hydroxyethyl)-2-pyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, N, N-dimethyllactamide, gamma-valerolactone, dihydrolevoglucosenone, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, methyl-1-methyl-2-oxopyrrolidone -4-carboxylate, 2-(2-oxopyrrolidin-1-yl)ethyl acetate and sulfolane, preferably N,N-dimethylacetamide.231351

[0067] 7

[0068] In a further preferred embodiment, component (D) consists essentially of at least one solvent selected from the group consisting of N-methylpyrrolidone, N-butylpyrrolidone, N-tert-buty I pyrrolidone, N-(2'-hydroxyethyl)-2-pyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethyllactamide, gamma-valerolactone, dihydrolevoglucosenone, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, methyl-1-methyl-2-oxopyrrolidone -4-carboxylate, 2-(2-oxopyrrolidin-1-yl)ethyl acetate and sulfolane, preferably N,N-dimethylacetamide.

[0069] "Consist essentially of”, in the present case, is understood to mean that component (D) comprises more than 98 % by weight, particularly preferably more than 99 % by weight, more preferably more than 99.5 % by weight, of at least one solvent selected from the group consisting of N-methylpyrrolidone, N-butylpyrrolidone, N-tert-buty I pyrrolidone, N-(2'-hydroxyethyl)-2-pyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethyllactamide, gamma-valerolactone, dihydrolevoglucosenone, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, methyl-1-methyl-2-oxopyrrolidone -4-carboxylate, 2-(2-oxopyrrolidin-1-yl)ethyl acetate and sulfolane, preferably N,N-dimethylacetamide.

[0070] The first solution (S1) preferably comprises in the range from 50 to 99.999 % by weight of the at least one solvent (D), more preferably in the range from 70 to 99.9 % by weight and most preferably in the range from

[0071] 75 to 99.5 % by weight of the at least one solvent (D) based on the total weight of the first solution (S1 ).

[0072] To the person skilled in the art, it is clear that the percentages by weight of the at least one recycled polyarylene ether sulfone polymer (rP) and the at least one solvent (D) comprised in the first solution (S1) typically add up to 100 % by weight.

[0073] The duration of step a) may vary between wide limits. The duration of step a) is preferably in the range from 10 min to 48 h (hours), especially in the range from 10 min to 24 h and more preferably in the range from 15 min to 12 h. A person skilled in the art will choose the duration of step a) so as to obtain a homogeneous solution of the at least one recycled polyarylene ether sulfone polymer (rP) in the at least one solvent (D).

[0074] Step b)

[0075] In step b), the first solution (S1) is filtered to obtain a filtered solution (fS).

[0076] Preferably, the filtering of the first solution (S1) in step b) is carried out with a filter comprising a diameter in the range from 1 to 10 pm, more preferably in the range from 1 to 5 pm.

[0077] Therefore, another object of the present invention is also a use wherein the filtering of the first solution (S1) in step b) is carried out with a filter comprising a diameter in the range from 1 to 10 pm.231351

[0078] 8

[0079] The filtered solution (fS) preferably has a turbidity < 50 NTU, more preferably < 25 NTU and most preferably < 5 NTU. The turbidity is measured with a turbidimeter 2100AN (Hach Lange GmbH, Dusseldorf, Germany) employing a filter of 860 nm at 60 °C and expressed in nephelometric turbidity units (NTU).

[0080] Step c)

[0081] In step c), at least one water soluble additive (C) is added to the filtered solution (fS) obtained in step b) to obtain a second solution (S2) comprising the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A), at least one solvent (D), and the at least one water soluble additive (C).

[0082] Component (C) / At least one water soluble additive (C)

[0083] At least one water soluble additive (C) is added to the filtered solution (fS). "At least one water soluble additive”, according to the invention, is understood to mean exactly one water soluble additive and also mixtures of two or more water soluble additives.

[0084] Suitable water soluble additives are poly (alkylene oxides) and poly (vinyl pyrrolidone).

[0085] Examples for suitable poly (alky lene oxides) are poly (ethylene oxide), poly (propylene oxide) and poly (ethylene oxide)-poly (propylene oxide) copolymer. Preferred poly (alky lene oxides) are poly (ethylene oxides) PEG 400 to 2,000,000 g / mol.

[0086] As poly(vinyl pyrrolidone) poly(vinyl pyrrolidone) K12 to 90 is preferred.

[0087] As water soluble additive (C), poly (vinyl pyrrolidone) is preferred.

[0088] Another object of the present invention is therefore also a use wherein the at least one water soluble additive (C) is selected from the group consisting of poly (vinyl pyrrolidone) and poly(alkylene oxides).

[0089] The second solution (S2) can comprise the at least one water soluble additive, for example, in an amount of from 3 to 20 % by weight, preferably in the range from 3 to 15 % by weight, based on the total weight of the second solution (S2).

[0090] In a preferred embodiment, the second solution (S2) comprises from 1 to 40% by weight of the at least one recycled polyarylene ether sulfone polymer (rP), from 3 to 20% by weight of the at least one water soluble additive (C) and from 40 to 96% by weight of the at least one solvent (D), based in each case on the total weight of the second solution (S2).231351

[0091] 9

[0092] Therefore, another object of the present invention is also a use wherein the second solution (S2) comprises from 1 to 40% by weight of the at least one recycled polyarylene ether sulfone polymer (rP), from 3 to 20% by weight of the at least one water soluble additive (C) and from 40 to 96% by weight of the at least one solvent (D), based in each case on the total weight of the second solution (S2).

[0093] In a more preferred embodiment, the second solution (S2) comprises from 5 to 30% by weight of the at least one recycled polyarylene ether sulfone polymer (rP), from 3 to 15% by weight of the at least one water soluble additive (C) and from 55 to 92% by weight of the at least one solvent (D), based in each case on the total weight of the second solution (S2).

[0094] To the person skilled in the art, it is clear that the percentages by weight of the recycled polyarylene ether sulfone polymer (rP), the at least one water soluble additive (C) and the at least one solvent comprised in the second solution (S2) typically add up to 100 % by weight.

[0095] The duration of step c) may vary between wide limits. The duration of step c) is preferably in the range from 10 min to 48 h (hours), especially in the range from 10 min to 24 h and more preferably in the range from 15 min to 12 h. A person skilled in the art will choose the duration of step c) so as to obtain a homogeneous solution of the recycled polyarylene ether sulfone polymer (rP) and the at least one water soluble additive (C) in the at least one solvent.

[0096] In step d), the at least one water soluble additive (C) and the at least one solvent (D) are separated from the second solution (S2) obtained in step c) to obtain the membrane (M).

[0097] Flat sheet membrane

[0098] In case, the membrane (M) is a flat sheet membrane (M), step d), for example, comprises the following steps:

[0099] d-1) casting the second solution (S2) obtained in step c) to obtain a film of the second solution (S2),

[0100] d-2) immersing the film of the second solution (S2) into at least one protic polar solvent (P1 ), wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the film of the second solution (S2) is at least partly separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the film of the second solution (S2), to obtain a membrane (M1) which is in the form of a film, and

[0101] d-3) washing the membrane (M1) with water, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M1) is essentially completely separated from the at least onewater soluble additive (C) and the at least one solvent (D) comprised in the membrane (M1) to obtain the membrane (M).

[0102] Therefore, another object of the present invention is also a use wherein step d) comprises the following steps:

[0103] d-1) casting the second solution (S2) obtained in step c) to obtain a film of the second solution (S2),

[0104] d-2) immersing the film of the second solution (S2) into at least one protic polar solvent (P1 ), wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the film of the second solution (S2) is at least partly separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the film of the second solution (S2), to obtain a membrane (M1) which is in the form of a film, and

[0105] d-3) washing the membrane (M1) with water, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M1) is essentially completely separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the membrane (M1) to obtain the membrane (M).

[0106] Step d-1)

[0107] In step d-1), the second solution (S2) obtained in step c) is cast to obtain a film of the second solution (S2).

[0108] The second solution (S2) can be cast by any method known to the skilled person. Usually, the second solution (S2) is cast with a casting knife that is heated to a temperature in the range from 20 to 150 °C, preferably in the range from 40 to 80°C.

[0109] Therefore, another object of the present invention is also a use wherein step d-1) is carried out at a temperature in the range of 40 to 80°C.

[0110] The second solution (S2) is usually cast on a substrate that does not react with the at least one recycled polyarylene ether sulfone polymer (rP), the at least one water soluble additive (C) or the at least one solvent (D) comprised in the second solution (S2).

[0111] Suitable substrates are known to the skilled person and are, for example, selected from glass plates and polymer fabrics such as non-woven materials.

[0112] Step d-2)11

[0113] In step d-2, the film of the second solution (S2) is immersed into at least one protic polar solvent (P 1), wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the film of the second solution (S2) is at least partly separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the film of the second solution (S2), to obtain a membrane (M1) which is in the form of a film.

[0114] The film of the second solution (S2) is preferably immersed into at least one protic polar solvent (P1) at a temperature in the range of 20 to 80°C, more preferably at a temperature in the range of 20 to 60°C.

[0115] In a preferred embodiment, the at least one protic polar solvent (P1) is a water-based coagulation bath. Preferably, the water-based coagulation bath comprises from 20 to 80 wt.-% of the solvent (D) and 20 to 80 wt.-% of water, more preferably from 50 to 80 wt.-% of the solvent (D) and 20 to 50 wt.-% of water, based on the total weight of the waterbased coagulation bath.

[0116] Therefore, another object of the present invention is also a use wherein the at least one protic polar solvent (P1 ) is a water-based coagulation bath.

[0117] The term "at least partly” within the context of the present invention means that preferably at least 50% by weight, more preferably at least 60% by weight, of the at least one recycled polyarylene ether sulfone polymer (rP), based on the total weight of the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the film of the second solution (S2), are separated from the at least one water soluble additive (C) and the at least one solvent (D) .

[0118] Step d-3)

[0119] In step d-3, the membrane (M1) is washed with water, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M 1 ) is essentially completely separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the membrane (M1) to obtain the membrane (M).

[0120] The term "essentially completely” within the context of the present invention means that preferably at least 90% by weight, more preferably at least 95% by weight, of the at least one recycled polyarylene ether sulfone polymer (rP), based on the total weight of the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M 1 ), are separated from the at least one water soluble additive (C) and the at least one solvent (D).

[0121] In step d-3), the membrane (M1) is preferably washed at a temperature in the range of 20 to 100°C, more preferably at a temperature in the range of 50 to 70°C.

[0122] In a preferred embodiment, the membrane (M1) is also washed with a 0.5 wt.-% solution of sodium bisulfite to remove active chlorine.12

[0123] Before washing, the membrane (M) can also be exposed to a water bath containing a NaOCI solution at 60 °C and a pH of 9.5.

[0124] The membrane (M) obtained in step d-3) is preferably a flat sheet membrane.

[0125] Hollow fibre membrane

[0126] In case, the membrane (M) is a hollow fiber membrane (M), step d), for example, comprises the following steps:

[0127] d-i) extruding the second solution (S2) obtained in step c) together with at least one protic polar solvent (P2) through a spinneret, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the second solution (S2) is at least partly separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the second solution (S2), to obtain a membrane (M2) which is in the form of hollowfibres, and

[0128] d-ii) washing the membrane (M2) with water, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M2) is essentially completely separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the membrane (M2) to obtain the membrane (M).

[0129] Another object of the present invention is therefore also the use wherein step d) comprises the following steps:

[0130] d-i) extruding the second solution (S2) obtained in step c) together with at least one protic polar solvent (P2) through a spinneret, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the second solution (S2) is at least partly separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the second solution (S2), to obtain a membrane (M2) which is in the form of hollowfibres, and

[0131] d-ii) washing the membrane (M2) with water, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M2) is essentially completely separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the membrane (M2) to obtain the membrane (M).

[0132] Step d-i)

[0133] In step d-i), the second solution (S2) obtained in step c) is extruded together with at least one protic polar solvent (P2) through a spinneret, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the13

[0134] second solution (S2) is at least partly separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the second solution (S2), to obtain a membrane (M2) which is in the form of hollow fibres.

[0135] Preferably, the hollow fibres are performed by extruding the second solution (S2) through a spinneret with the required number of hollow needles. The at least one protic polar solvent (P2) is preferably injected through the hollow needles into the second solution (S2) during extrusion, so that parallel continuous channels extending in extrusion direction are formed. The at least one protic polar solvent (P2) is also referred to as centre fluid.

[0136] The term "at least partly” within the context of the present invention means that preferably at least 50% by weight, more preferably at least 60% by weight, of the at least one recycled polyarylene ether sulfone polymer (rP), based on the total weight of the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the second solution (S2), are separated from the at least one water soluble additive (C) and the at least one solvent (D).

[0137] In a preferred embodiment, the at least one protic polar solvent (P2) is a water-based coagulation bath. Preferably, the water-based coagulation bath comprises from 20 to 80 wt.-% of the solvent (D) and 20 to 80 wt.-% of water, more preferably from 50 to 80 wt.-% of the solvent (D) and 20 to 50 wt.-% of water, based on the total weight of the waterbased coagulation bath.

[0138] Another object of the present invention is therefore also the use wherein the at least one protic polar solvent (P2) is a water-based coagulation bath.

[0139] Preferably, the second solution (S2) is extruded together with at least one protic polar solvent (P2) through a spinneret at a temperature in the range from 20 to 150 °C, preferably in the range from 40 to 80°C.

[0140] Therefore, another object of the present invention is also a use wherein step d-i) is carried out at a temperature in the range of 40 to 80°C.

[0141] Optionally, the second solution (S2) is extruded together with at least one protic polar solvent (P2) through a steam curtain.

[0142] The diameter of the spinneret is preferably 0.8 mm - 1.0 mm - 1.6 mm.

[0143] In a preferred embodiment, step d-i) is carried out at a spinning speed in the range of 15 to 25 cm / min, preferably in the range of 16 to 20 cm / min.

[0144] The second solution (S2) and the at least one protic polar solvent (P2) preferably leave the spinneret with a speed in the range of 2 to 6 ml / min.14

[0145] The membrane (M2) is preferably passed into a water bath having a temperature in the range of 40 to 80° C. The distance between the spinneret and the water bath is preferably in the range of 10 to 30 cm.

[0146] After passing into a water bath, the membrane (M2) is preferably wound onto a winding reel and transferred into a water bath containing a NaOCI solution at 60 °C and a pH of 9.5.

[0147] Step d-ii)

[0148] In step d-ii), the membrane (M2) is washed with water, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M2) is essentially completely separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the membrane (M2) to obtain the membrane (M).

[0149] The term "essentially completely” within the context of the present invention means that preferably at least 90% by weight, more preferably at least 95% by weight, of the at least one recycled polyarylene ether sulfone polymer (rP), based on the total weight of the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M2), are separated from the at least one water soluble additive (C) and the at least one solvent (D).

[0150] In step d-ii), the membrane (M2) is preferably washed at a temperature in the range of 20 to 100°C, more preferably at a temperature in the range of 50 to 70°C.

[0151] In a preferred embodiment, the membrane (M2) is also washed with a 0.5 wt.-% solution of sodium bisulfite to remove active chlorine.

[0152] Before washing, as mentioned above, the membrane (M2) can also be exposed to a water bath containing a NaOCI solution at 60 °C and a pH of 9.5.

[0153] The membrane (M) obtained in step d-ii) is preferably a hollow fibre membrane.

[0154] Membrane (M)

[0155] The membrane (M) obtained by the inventive method can be used for technical filtration applications or for carbon capture storage applications.

[0156] Another object of the present invention is therefore also the use wherein the membrane (M) is used for technical filtration applications or for carbon capture storage applications.

[0157] The membrane (M) preferably has231351

[0158] 15

[0159] i) a molecular weight cut-off in the range from 20 to 200 kDa, more preferably in the range from 50 to 200 kDa, and / or

[0160] ii) a pure water permeation in the range from 100 to 1200 kg / (h m2bar), more preferably in the range from 700 to 1200 kg / (h m2bar).

[0161] Another object of the present invention is therefore also the use wherein the membrane (M) has

[0162] i) a molecular weight cut-off in the range from 20 to 200 kDa, and / or

[0163] II) a pure water permeation in the range from 100 to 1200 kg / (h m2bar).

[0164] The present invention is further elucidated by the following examples without limiting it thereto.

[0165] Examples

[0166] Abbreviations and components used

[0167] Component (A): recycled polysulfone (rPSU)

[0168] Polysulfone fiber waste from dialyzer fabrication of Fresenius medical care AG & Co. KGaA (St. Wendel, Germany) was processed at 330 °C to granulate (rPSU). The material contains 6.5 wt.-% polyvinylpyrrolidone according to IR-spectroscopy and a viscosity number (measured based on ISO 1628-5 (1998) in a 1 wt.-% polymer solution in N-methylpyrrolidone) of 69 ml / g; a glass transition temperature (measured by DSC, 10°C / min, according to ISO 11357-1 / -2) of 186 °C; a molecular weight Mw (GPC in THF, PS standard): 60600 g / mol, Mw / Mn = 3.6

[0169] Component (C): Poly (vinyl pyrrolidone) (PVP; Luvitec® K90)

[0170] Polyvinylpyrrolidone with a solution viscosity characterised by the K-value of 90, determined according to the method of Fikentscher (Fikentscher, Cellulosechemie 13, 1932 (58))

[0171] Component (D): N,N-dimethylacetamide (DMAc)

[0172] PSU: Polysulfone (Ultrason® S 6010)

[0173] Polysulfone with a viscosity number (measured based on ISO 1628-5 (1998) in a 1 wt.-% polymer solution in N-methylpyrrolidone) of 81 ml / g; a glass transition temperature (measured231351

[0174] 16

[0175] by DSC, 10°C / min, according to ISO 11357-1 / -2) of 187 °C; a molecular weight Mw (GPC in THF, PS standard) of 60000 g / mol, Mw / Mn = 3.7

[0176] DMF: N,N-dimethylformamide

[0177] General procedures

[0178] Turbidity

[0179] The polymer solution turbidity was measured with a turbidimeter 2100AN (Hach Lange GmbH, Dusseldorf, Germany) employing a filter of 860 nm at 60 °C and expressed in nephelometric turbidity units (NTU). NTU values below 5 are preferred.

[0180] Viscosity

[0181] The polymer solution viscosity was measured with a Brookfield Viscometer DV-I Prime (Brookfield Engineering Laboratories, Inc. Middleboro, USA) with RV 6 spindle at 60 °C with 20 rpm.

[0182] Determination of the membrane water permeability

[0183] The pure water permeability (PWP) of the flat sheet membranes was tested using a pressure cell with a diameter of 74 mm using ultrapure water (salt-free water, filtered by a Millipore UF-system) at 23 °C and 1 bar water pressure. For the single bore fibers a mini module was used to determine the PWP at 23 °C and 1 bar trans membrane pressure. The pure water permeability (PWP) is calculated as follows (equation 1):

[0184] m

[0185] PWP =

[0186] AxPxt

[0187] (1)

[0188] PWP: pure water permeability [kg I bar h m2]

[0189] m: mass of permeated water [kg]

[0190] A: membrane area [m2]

[0191] P: pressure [bar]

[0192] t: time of the permeation experiment [h].231351

[0193] 17

[0194] Determination of the membrane’s MWCO (Molecular weight cut off)

[0195] In a subsequent test, solutions of poly (ethylene oxide)-standards with increasing molecular weight were used as feed to be filtered by the membrane at a pressure of 0.15 bar. By GPC-measurement of the feed and permeate, the molecular weight of the permeate of each poly (ethylene oxide)-standard used was determined.

[0196] PVP content

[0197] The polyvinylpyrrolidone content of the PSU was determined by dissolving the polymer sample in N,N-dimethylformamide (DMF) and casting the solution as film on KRS-5 windows of thalliumbromiodide. The films were dried at 160 °C and analyzed with a Nicolet 6700 FT-IR spectrometer (Thermo Fischer Scientific, Waltham, Massachusetts, USA). Together with calibration samples of known polyvinylpyrrolidone content, the adsorption band at 1680 cm1was used to determine the overall polyvinylpyrrolidone content of the polymer sample.

[0198] Preparation of polymer solutions for membrane preparation (Second solution (S2))

[0199] The amounts given in this general procedure are general ranges, the exact amount for the respective experiment can be found in table 1. A clear viscous solution (First solution (S1)), usually referred to as solution of the membrane polymer in DMAc (Component (D)) was prepared using a SpeedMixer® DAC 600.1 Vac-P (Hauschild & Co. KG, Hamm, Germany) at speeds of 200, 800 and 1200 rpm within 30 minutes of mixing. The solution (First solution (S1)) was filtered with 3 pm filter (Tiefenfilterschicht TFS-3, DSP Filtertechnik, Am Eichelweg 14, D-55430 Perscheid, Germany) to obtain a filtered solution (fS), and 6 wt.-% polyvinylpyrrolidone were dissolved using SpeedMixer® DAC 600.1 Vac-P. The obtained second solution (S2) was subsequently degassed overnight at room temperature.

[0200] Table 1: Compositions and properties of (r)PSU solutions

[0201]

[0202] Preparation of flat sheet membranes

[0203] The polymer solution (Second Solution (S2)) was reheated at 60 °C for 2 hours and casted onto a glass plate with a casting knife (300 microns) at 60 °C using an Erichsen Coating machine (Coatmaster 510, Erichsen GmbH & Co KG, Hemer, Germany) operating at a speed of 5 mm / s. The obtained film was allowed to rest for 30 seconds before immersion at 25 °C for 10 minutes in a water-based coagulation bath consisting of a mixture of the same solvent231351

[0204] 18

[0205] used for the preparation of the above-mentioned polymer solution and water at a ratio of 60:40 based on weight. After the obtained membrane had detached from the glass plate, the membrane was transferred into a water bath containing a 2.000 ppm NaOCI solution at 60 °C and a pH of 9.5 for 2 h. The membrane was then washed with water at 60 °C and one time with a 0.5 wt.-% solution of sodium bisulfite to remove active chlorine. After the posttreatment the membranes are stored in a wet state.

[0206] Table 2: Properties of (r)PSU flat sheet membranes

[0207]

[0208] * determined by scanning electron microscopy (SEM) (750 x magnification)

[0209] As can be seen from table 2, the flat sheet membrane (M) according to the invention comprising the at least one recycled polyarylene ether sulfone polymer (rP) shows a good water permeability (PWP) of > 700 kg / h m2bar and a Molecular weight cut off (MWCO) of < 200 kDa so that it can be used for technical filtration applications or for carbon capture storage applications.

[0210] Figure 1 shows a cross-section of the membrane of comparative example C2. Figure 2 shows a cross-section of the membrane of inventive example 2 (all figures 750 x magnification). As can be seen from the figures, the membranes 2 and C2 reveal identical membrane morphologies. Both membranes have a nano-porous filtration layer on the top of 10 to 15 pm thickness which are supported by spongy-type substructure with increasing pore size towards the bottom.

[0211] Preparation of hollow fiber membranes

[0212] A hollow fiber membrane was formed by reheating the polymer solution (Second Solution (S2)) at 60°C for 2 hours and passing the solution as well as the center fluid through a spinning die. A center fluid was prepared by mixing distilled water and DMAc. The weight fraction of the two components in the center fluid was: water : DMAc = 40 wt.-%: 60 wt.-%.The diameter of the spinning die was 0.8 mm - 1.0 mm - 1.6 mm. The temperature of the die was 60 °C. The hollow fiber membrane was formed at a spinning speed of 18 cm / min. The polymer solution was leaving the die with 4.0 ml / min while the center fluid was leaving the die with 4.0 ml / min. The liquid capillary was passed into a water bath having a temperature of 60 °C. The distance between the die and the precipitation bath was 13 cm. The hollow fiber membrane formed was guided through one water bath and subsequently was wound onto a winding reel. Subsequently the hollow fiber membrane was transferred into a water bath containing a 2000 ppm NaOCI solution at 60 °C and a pH of 9.5 for 2 h. The membrane was then washed with water at 60 °C and one time with a 0.5 wt.-% solution of sodium bisulfite to remove active chlorine. After the posttreatment the membranes are stored in a wet231351

[0213] 19

[0214] state. Subsequently, the membranes were submerged in a solution of 1 ,2-propandiole, glycerol and water (10, 20, and 70 wt%) for 1 h at 60 °C and then dried over night at 50 °C. Finally, the obtained membranes were then assembled into mini modules.

[0215] The 17 cm long module bodies were made of PVC-U and supplied by Krabbe Engineering B.V. (Weerselo, Netherlands). This PVC pipe (diameter 10 mm) had one opening which was placed a few centimeters away from the ends of the tube. These allowed the passage of filtrate. The pipes fitted special end connectors on the filtration equipment. A total of seven single bore fibers were selected, cut to 20 cm length, and placed in these PVC tubes. One side of the membrane fibers was sealed with an epoxy resin. After this was hardened, the membranes were potted with another epoxy resin into the PVC tube. After this epoxy was cured, the extending epoxy was cut off, leaving the membrane capillaries open. This procedure was repeated on the second side of the module. An integrity test was conducted on the module, to ensure the membranes were not damaged during the handling of the membranes and module. This was accomplished by holding the module under water and pressurizing the filtrate side of the module with compressed air at 1 bar. Exiting air bubbles from the capillaries or epoxy indicated the presence of defects.

[0216] Table 3: Properties of (r)PSU hollow fiber membranes

[0217]

[0218] * determined by scanning electron microscopy (SEM) (750 x magnification)

[0219] As can be seen from table 3, the hollow fiber membrane (M) according to the invention comprising the at least one recycled polyarylene ether sulfone polymer (rP) shows a good water permeability (PWP) of > 700 kg / h m2bar and a Molecular weight cut off (MWCO) of < 200 kDa so that it can be used for technical filtration applications or for carbon capture storage applications.

[0220] Figures 3 and 5 show a cross-section of the membrane of comparative example C3. Figures 4 and 6 show a crosssection of the membrane of inventive example 3 (150 x and 1500 x magnification). As can be seen from the figures, the membranes 3 and C3 reveal identical membrane morphologies.

Claims

Claims1. The use of(A) at least one recycled polyarylene ether sulfone polymer (rP)in a method for the preparation of a membrane (M), the membrane (M) comprising the at least one recycled polyarylene ether sulfone polymer (rP),wherein the method comprises the steps a) to d)a) providing a first solution (S1) which comprises the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A) and at least one solvent (D),b) filtering the first solution (S1) to obtain a filtered solution (fS),c) adding at least one water soluble additive (C) to the filtered solution (fS) obtained in step b) to obtain a second solution (S2) comprising the at least one recycled polyarylene ether sulfone polymer (rP) according to component (A), at least one solvent (D), and the at least one water soluble additive (C),d) separating the at least one water soluble additive (C) and the at least one solvent (D) from the second solution (S2) obtained in step c) to obtain the membrane (M),wherein the recycled polyarylene ether sulfone polymer (rP) has a weight-average molecular weight (Mw) of from 40000 to 70000 g / mol.

2. Use according to claim 1 , wherein step d) comprises the following steps:d-1) casting the second solution (S2) obtained in step c) to obtain a film of the second solution (S2),d-2) immersing the film of the second solution (S2) into at least one protic polar solvent (P1 ), wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the film of the second solution (S2) is at least partly separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the film of the second solution (S2), to obtain a membrane (M1) which is in the form of a film, and21d-3) washing the membrane (M1) with water, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M1) is essentially completely separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the membrane (M1) to obtain the membrane (M).

3. Use according to claim 1 , wherein step d) comprises the following steps:d-i) extruding the second solution (S2) obtained in step c) together with at least one protic polar solvent (P2) through a spinneret, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the second solution (S2) is at least partly separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the second solution (S2), to obtain a membrane (M2) which is in the form of hollow fibres, andd-ii) washing the membrane (M2) with water, wherein the at least one recycled polyarylene ether sulfone polymer (rP) comprised in the membrane (M2) is essentially completely separated from the at least one water soluble additive (C) and the at least one solvent (D) comprised in the membrane (M2) to obtain the membrane (M).

4. Use according to any of claims 1 to 3, wherein the at least one recycled polyarylene ether sulfone polymer (rP) hasi) a viscosity number in the range of from 60 to 85 ml / g, and / orii) a glass transition temperature (TG(PP)) in the range of from 180 to 190 °C, and / oriii) a polydispersity in the range of from 2 to 4.

5. Use according to any of claims 1 to 4, wherein the at least one solvent (D) is selected from the group consisting of N-methylpyrrolidone, N-butylpyrrolidone, N-tert-buty I pyrrolidone, N-(2'-hydroxyethyl)- 2-pyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, N, N-dimethyllactamide, gamma-valerolactone, dihydrolevoglucosenone, methyl 5-(dimethylamino)-2-methyl-5-oxopentanoate, methyl-1-methyl-2-oxopyrrolidone -4-carboxylate, 2-(2-oxopyrrolidin-1-yl)ethyl acetate and sulfolane, preferably N,N-dimethylacetamide.

6. Use according to any of claims 1 to 5, wherein the at least one water soluble additive (C) is selected from the group consisting of poly (vinyl pyrrolidone) and poly (alkylene oxides).

7. Use according to any of claims 1 to 6, wherein the at least one recycled polyarylene ether sulfone polymer (rP) is a recycled polysulfone (rPSU).

228. Use according to any of claims 1 to 7, wherein the second solution (S2) comprises from 1 to 40% by weight of the at least one recycled polyarylene ether sulfone polymer (rP), from 3 to 20% by weight of the at least one water soluble additive (C) and from 40 to 96% by weight of the at least one solvent (D), based in each case on the total weight of the second solution (S2).

9. Use according to any of claims 2 to 8, whereini) the at least one protic polar solvent (P1) is a water-based coagulation bath, and / or ii) step d-1) is carried out at a temperature in the range of 40 to 80°C.

10. Use according to any of claims 3 to 9, whereinI) the at least one protic polar solvent (P2) is a water-based coagulation bath, and / orII) step d-i) is carried out at a temperature in the range of 40 to 80°C.

11. Use according to any of claims 1 to 10, wherein the at least one recycled polyarylene ether sulfone polymer (rP)I) is obtained by processing polyarylene ether sulfone polymer fibre waste from dialyzer fabrication into granulate, and / orII) comprises in the range of from 1 to 10 wt% of poly(vinyl pyrrolidone).

12. Use according to any of claims 1 to 11, wherein the filtering of the first solution (S1) in step b) is carried out with a filter comprising a diameter in the range from 1 to 10 pm.

13. Use according to any of claims 1 to 12, wherein the membrane (M) hasI) a molecular weight cut-off in the range from 20 to 200 kDa, and / orII) a pure water permeation in the range from 100 to 1200 kg / (h m2 bar).

14. Use according to any of claims 1 to 13, wherein the membrane (M) is used for technical filtration applications or for carbon capture storage applications.

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