WO2015189175A1

WO2015189175A1 - New membranes

Info

Publication number: WO2015189175A1
Application number: PCT/EP2015/062774
Authority: WO
Inventors: Martin Weber; Thomas Weiss
Original assignee: Basf Se
Priority date: 2014-06-13
Filing date: 2015-06-09
Publication date: 2015-12-17

Abstract

Membrane comprising at least one polymer A and at least one phenoxy resin P, wherein said phenoxy resin P comprises a phenoxy backbone and at least one hydrophilic side chain, wherein said hydrophilic side chain has a solubility in water of greater than 5 g/l.

Description

New membranes

The present invention is related to membranes comprising at least one Polymer A and at least one phenoxy resin P, wherein said phenoxy resin P comprises a phenoxy backbone and at least one hydrophilic side chain, wherein said hydrophilic side chain has a solubility in water of greater than 5 g/l.

The present invention is further related to new phenoxy resins bearing hydrophilic side groups and to processes for making such phenoxy resins and polymer blends containing such resins. Membranes play an increasingly important role in many aspects of life. Normally, membranes comprise a hydrophobic polymer as the main component. Materials that are often used for making membranes include polyvinylidene difluoride and polyarylene ethers.

One disadvantage of pure polyarylene ethers is their low hydrophilicity. To enhance the hydro- philicity of polyarylene ethers, polyethersulfone (PESU) - polyethyleneoxide (PEO) block copolymers have been prepared.

EP 739 925, US 5,700,902 and US 5,700,903 describe polyarylene ether and polyalkylene oxide copolymers.

US 5,700,902 discloses block copolymers with hydrophobic blocks and hydrophilic blocks, wherein hydrophilic blocks can be PEO blocks that are endcapped on one side with an alkyl group. US 5,798,437, US 5,834,583, WO 97/22406 disclose processes for the manufacture of hydrophilic copolymers.

US 5,91 1 ,880 discloses membranes made of polyether sulfone comprising an amphiphilic additive.

EP 739 925 A1 discloses polysulfone-polyether block copolycondensates.

It was an objective of the present invention to provide membranes that are mechanically flexible, easily wettable with water and that have a high upper glass transition temperature.

This objective has been solved by membranes comprising at least one Polymer A and at least one phenoxy resin P, wherein said phenoxy resin P comprises a phenoxy backbone and at least one hydrophilic side chain, wherein said hydrophilic side chain has a solubility in water of greater than 5 g/l.

Preferably, said polymer A is a polyarylene ether, herein also referred to as polyarylene ether A.

In the context of this application a membrane shall be understood to be a thin, semipermeable structure capable of separating two fluids or separating molecular and/or ionic components or particles from a liquid. A membrane acts as a selective barrier, allowing some particles, substances or chemicals to pass through, while retaining others.

For example, membranes according to the invention can be reverse osmosis (RO) membranes, forward osmosis (FO) membranes, nanofiltration (NF) membranes, ultrafiltration (UF) membranes or microfiltration (MF) membranes. These membrane types are generally known in the art and are further described below.

FO membranes are normally suitable for treatment of seawater, brackish water, sewage or sludge streams. Thereby pure water is removed from those streams through a FO membrane into a so called draw solution on the back side of the membrane having a high osmotic pressure.

In a preferred embodiment, suitable FO membranes are thin film composite (TFC) FO mem- branes. Preparation methods and use of thin film composite membranes are principally known and, for example described by R. J. Petersen in Journal of Membrane Science 83 (1993) 81 - 150.

In a particularly preferred embodiment, suitable FO membranes comprise a fabric layer, a sup- port layer, a separation layer and optionally a protective layer. Said protective layer can be considered an additional coating to smoothen and/or hydrophilize the surface.

Said fabric layer can for example have a thickness of 10 to 500 μηη. Said fabric layer can for example be a woven or nonwoven, for example a polyester nonwoven.

Said support layer of a TFC FO membrane normally comprises pores with an average pore diameter of for example 0.5 to 100 nm, preferably 1 to 40 nm, more preferably 5 to 20 nm. Said support layer can for example have a thickness of 5 to 1000 μηη, preferably 10 to 200 μηη. Said support layer may for example comprise as the main component a polysulfone, polyethersul- fone, polyphenylenesulfone, polyvinylidenedifluoride, polyimide, polyimideurethane or cellulose acetate.

In one embodiment, FO membranes comprise a support layer comprising as the main component at least one polyamide (PA), polyvinylalcohol (PVA), Cellulose Acetate (CA), Cellulose Triacetate (CTA), CA-triacetate blend, Cellulose ester, Cellulose Nitrate, regenerated Cellulose, aromatic , aromatic/aliphatic or aliphatic Polyamide, aromatic, aromatic/aliphatic or aliphatic Polyimide, Polybenzimidazole (PBI), Polybenzimidazolone (PBIL), Polyacrylonitrile (PAN), PAN-poly(vinyl chloride) copolymer (PAN-PVC), PAN-methallyl sulfonate copolymer,

Poly(dimethylphenylene oxide) (PPO), Polycarbonate, Polyester, Polytetrafluroethylene (PTFE), Poly(vinylidene fluoride) (PVDF), Polypropylene (PP), Polyelectrolyte complexes, Poly(methyl methacrylate) PMMA, Polydimethylsiloxane (PDMS), aromatic, aromatic/aliphatic or aliphatic polyimide urethanes, aromatic, aromatic/aliphatic or aliphatic polyamidimides, crosslinked poly- imides or polyarylene ether, polysulfone (PSU), polyphenylenesulfone (PPSU) or polyethersul- fone (PESU), or mixtures thereof in combination with phenoxy resins P.

In another preferred embodiment, FO membranes comprise a support layer comprising as the main component at least one polysulfone, polyphenylenesulfone and/or polyethersulfone in combination with at least one phenoxy resin P.

Nano particles such as zeolites may be comprised in said support membrane. This can for ex- ample be achieved by including such nano particles in the dope solution for the preparation of said support layer.

Said separation layer of a FO membrane can for example have a thickness of 0.05 to 1 μηη, preferably 0.1 to 0.5 μηη, more preferably 0.15 to 0.3 μηη. Preferably, said separation layer can for example comprise polyamide or cellulose acetate as the main component.

Optionally, TFC FO membranes can comprise a protective layer with a thickness of 30-500 preferable 100-300 nm. Said protective layer can for example comprise polyvinylalcohol (PVA) as the main component. In one embodiment, the protective layer comprises a halamine like chloramine.

In one preferred embodiment, suitable membranes are TFC FO membranes comprising a support layer comprising at least one polysulfone, polyphenylenesulfone and/or polyethersulfone in combination with phenoxy resins P useful according to the invention, a separation layer com- prising polyamide as main component and optionally a protective layer comprising polyvinylalcohol as the main component.

In a preferred embodiment suitable FO membranes comprise a separation layer obtained from the condensation of a polyamine and a polyfunctional acyl halide. Said separation layer can for example be obtained in an interfacial polymerization process.

RO membranes are normally suitable for removing molecules and ions, in particular monovalent ions. Typically, RO membranes are separating mixtures based on a solution/diffusion mechanism.

In a preferred embodiment, suitable membranes are thin film composite (TFC) RO membranes. Preparation methods and use of thin film composite membranes are principally known and, for example described by R. J. Petersen in Journal of Membrane Science 83 (1993) 81 -150. In a further preferred embodiment, suitable RO membranes comprise a fabric layer, a support layer, a separation layer and optionally a protective layer. Said protective layer can be considered an additional coating to smoothen and/or hydrophilize the surface Said fabric layer can for example have a thickness of 10 to 500 μηη. Said fabric layer can for example be a woven or nonwoven, for example a polyester nonwoven.

Said support layer of a TFC RO membrane normally comprises pores with an average pore diameter of for example 0.5 to 100 nm, preferably 1 to 40 nm, more preferably 5 to 20 nm. Said support layer can for example have a thickness of 5 to 1000 μηη, preferably 10 to 200 μηη. Said support layer may for example comprise as the main component a polysulfone, polyethersulfone, polyphenylenesulfone, PVDF, polyimide, polyimideurethane or cellulose acetate.

In one embodiment, RO membranes comprise a support layer comprising as the main component at least one polyamide (PA), polyvinylalcohol (PVA), Cellulose Acetate (CA), Cellulose Triacetate (CTA), CA-triacetate blend, Cellulose ester, Cellulose Nitrate, regenerated Cellulose, aromatic , aromatic/aliphatic or aliphatic Polyamide, aromatic, aromatic/aliphatic or aliphatic Polyimide, Polybenzimidazole (PBI), Polybenzimidazolone (PBIL), Polyacrylonitrile (PAN), PAN-poly(vinyl chloride) copolymer (PAN-PVC), PAN-methallyl sulfonate copolymer,

Poly(dimethylphenylene oxide) (PPO), Polycarbonate, Polyester, Polytetrafluroethylene (PTFE), Poly(vinylidene fluoride) (PVDF), Polypropylene (PP), Polyelectrolyte complexes, Poly(methyl methacrylate) PMMA, Polydimethylsiloxane (PDMS), aromatic, aromatic/aliphatic or aliphatic polyimide urethanes, aromatic, aromatic/aliphatic or aliphatic polyamidimides, crosslinked poly- imides or polyarylene ether, polysulfone, polyphenylenesulfone or polyethersulfone, or mixtures thereof in combination with at least one phenoxy resin P.

In another preferred embodiment, RO membranes comprise a support layer comprising as the main component at least one polysulfone, polyphenylenesulfone and/or polyethersulfone in combination with at least one phenoxy resin P. Nano particles such as zeolites may be comprised in said support membrane. This can for example be achieved by including such nano particles in the dope solution for the preparation of said support layer.

Said separation layer can for example have a thickness of 0.02 to 1 μηη, preferably 0.03 to 0.5 μηη, more preferably 0.05 to 0.3 μηη. Preferably, said separation layer can for example comprise polyamide or cellulose acetate as the main component.

Optionally, TFC RO membranes can comprise a protective layer with a thickness of 5 to 500 preferable 10 to 300 nm. Said protective layer can for example comprise polyvinylalcohol (PVA) as the main component. In one embodiment, the protective layer comprises a halamine like chloramine. In one preferred embodiment, suitable membranes are TFC RO membranes comprising a nonwoven polyester fabric, a support layer comprising at least one polysulfone, polyphe- nylenesulfone and/or polyethersulfone in combination with at least one phenoxy resin P , a separation layer comprising polyamide as main component and optionally a protective layer com- prising polyvinylalcohol as the main component.

In a preferred embodiment suitable RO membranes comprise a separation layer obtained from the condensation of a polyamine and a polyfunctional acyl halide. Said separation layer can for example be obtained in an interfacial polymerization process.

Suitable polyamine monomers can have primary or secondary amino groups and can be aromatic (e. g. a diaminobenzene, a triaminobenzene, m-phenylenediamine, p-phenylenediamine, 1 ,3,5-triaminobenzene, 1 ,3,4-triaminobenzene, 3,5-diaminobenzoic acid, 2,4-diaminotoluene, 2,4-diaminoanisole, and xylylenediamine) or aliphatic (e. g. ethylenediamine, propylenediamine, piperazine, and tris(2-diaminoethyl)amine).

Suitable polyfunctional acyl halides include trimesoyl chloride (TMC), trimellitic acid chloride, isophthaloyl chloride, terephthaloyl chloride and similar compounds or blends of suitable acyl halides. As a further example, the second monomer can be a phthaloyl halide.

In one embodiment of the invention, a separation layer of polyamide is made from the reaction of an aqueous solution of meta-phenylene diamine MPD with a solution of trimesoyl chloride (TMC) in an apolar solvent.

NF membranes are normally especially suitable for removing multivalent ions and large monovalent ions. Typically, NF membranes function through a solution/diffusion or/and filtration- based mechanism. NF membranes are normally used in crossflow filtration processes.

In one embodiment, NF membranes comprise as the main component at least one polyamide (PA), polyvinylalcohol (PVA), Cellulose Acetate (CA), Cellulose Triacetate (CTA), CA-triacetate blend, Cellulose ester, Cellulose Nitrate, regenerated Cellulose, aromatic , aromatic/aliphatic or aliphatic Polyamide, aromatic, aromatic/aliphatic or aliphatic Polyimide, Polybenzimidazole

(PBI), Polybenzimidazolone (PBIL), Polyacrylonitrile (PAN), PAN-poly(vinyl chloride) copolymer (PAN-PVC), PAN-methallyl sulfonate copolymer, Poly(dimethylphenylene oxide) (PPO), Polycarbonate, Polyester, Polytetrafluroethylene (PTFE), Poly(vinylidene fluoride) (PVDF), Polypropylene (PP), Polyelectrolyte complexes, Poly(methyl methacrylate) PMMA, Polydimethylsilox- ane (PDMS), aromatic, aromatic/aliphatic or aliphatic polyimide urethanes, aromatic, aromatic/aliphatic or aliphatic polyamidimides, crosslinked polyimides or polyarylene ether, polysul- fone, polyphenylenesulfone or polyethersulfone, or mixtures thereof in combination at least one phenoxy resin P.

In another embodiment of the invention, NF membranes comprise as the main component at least one polysulfone, polyphenylenesulfone and/or polyethersulfone in combination with at least one phenoxy resin P.

In a particularly preferred embodiment, the main components of a NF membrane are positively or negatively charged.

Nanofiltration membranes often comprise charged polymers comprising sulfonic acid groups, carboxylic acid groups and/or ammonium groups in combination with block copolymers according to the invention. In another embodiment, NF membranes comprise as the main component polyamides, poly- imides or polyimide urethanes, Polyetheretherketone (PEEK) or sulfonated polyetherether- ketone (SPEEK), in combination with at least one phenoxy resin P.

UF membranes are normally suitable for removing suspended solid particles and solutes of high molecular weight, for example above 10000 Da. In particular, UF membranes are normally suitable for removing bacteria and viruses. UF membranes normally have an average pore diameter of 2 nm to 50 nm, preferably 5 to 40 nm, more preferably 5 to 20 nm.

In one embodiment, UF membranes comprise as the main component at least one polyamide (PA), polyvinylalcohol (PVA), Cellulose Acetate (CA), Cellulose Triacetate (CTA), CA-triacetate blend, Cellulose ester, Cellulose Nitrate, regenerated Cellulose, aromatic , aromatic/aliphatic or aliphatic Polyamide, aromatic, aromatic/aliphatic or aliphatic Polyimide, Polybenzimidazole (PBI), Polybenzimidazolone (PBIL), Polyacrylonitrile (PAN), PAN-poly(vinyl chloride) copolymer (PAN-PVC), PAN-methallyl sulfonate copolymer, Poly(dimethylphenylene oxide) (PPO), Polycarbonate, Polyester, Polytetrafluroethylene PTFE, Poly(vinylidene fluoride) (PVDF), Polypro- pylene (PP), Polyelectrolyte complexes, Poly(methyl methacrylate) PMMA, Polydimethylsilox- ane (PDMS), aromatic, aromatic/aliphatic or aliphatic polyimide urethanes, aromatic, aromatic/aliphatic or aliphatic polyamidimides, crosslinked polyimides or polyarylene ether, polysulfone, polyphenylenesulfone, or polyethersulfone, or mixtures thereof in combination with at least one phenoxy resin P. In another embodiment of the invention, UF membranes comprise as the main component at least one polysulfone, polyphenylenesulfone and/or polyethersulfone in combination with at least one phenoxy resin P. In one embodiment, UF membranes comprise further additives like polyvinyl pyrrolidones or polyalkylene oxides like polyethylene oxides.

In a preferred embodiment, UF membranes comprise as major components polysulfones, polyphenylenesulfone or polyethersulfone in combination with at least one phenoxy resin P and with further additives like polyvinylpyrrolidone.

In one preferred embodiment, UF membranes comprise 99.9 to 50% by weight of a combination of polyethersulfone and 0.1 to 50 % by weight of polyvinylpyrrolidone.

In another embodiment UF membranes comprise 95 to 80% by weight of polyethersulfone and 5 to 15 % by weight of polyvinylpyrrolidone.

In one embodiment of the invention, UF membranes are present as spiral wound membranes, as pillows or flat sheet membranes.

In another embodiment of the invention, UF membranes are present as tubular membranes.

In another embodiment of the invention, UF membranes are present as hollow fiber membranes or capillaries.

In yet another embodiment of the invention, UF membranes are present as single bore hollow fiber membranes.

In yet another embodiment of the invention, UF membranes are present as multibore hollow fiber membranes.

Multiple channel membranes, also referred to as multibore membranes, comprise more than one longitudinal channels also referred to simply as "channels".

In a preferred embodiment, the number of channels is typically 2 to 19. In one embodiment, multiple channel membranes comprise two or three channels. In another embodiment, multiple channel membranes comprise 5 to 9 channels. In one preferred embodiment, multiple channel membranes comprise seven channels.

In another embodiment the number of channels is 20 to 100.

The shape of such channels, also referred to as "bores", may vary. In one embodiment, such channels have an essentially circular diameter. In another embodiment, such channels have an essentially ellipsoid diameter. In yet another embodiment, channels have an essentially rectan- gular diameter.

In some cases, the actual form of such channels may deviate from the idealized circular, ellipsoid or rectangular form. Normally, such channels have a diameter (for essentially circular diameters), smaller diameter (for essentially ellipsoid diameters) or smaller feed size (for essentially rectangular diameters) of 0.05 mm to 3 mm, preferably 0.5 to 2 mm, more preferably 0.9 to 1 .5 mm. In another preferred embodiment, such channels have a diameter (for essentially circular diameters), smaller diame- ter (for essentially ellipsoid diameters) or smaller feed size (for essentially rectangular diameters) in the range from 0.2 to 0.9 mm.

For channels with an essentially rectangular shape, these channels can be arranged in a row. For channels with an essentially circular shape, these channels are in a preferred embodiment arranged such that a central channel is surrounded by the other channels. In one preferred embodiment, a membrane comprises one central channel and for example four, six or 18 further channels arranged cyclically around the central channel. The wall thickness in such multiple channel membranes is normally from 0.02 to 1 mm at the thinnest position, preferably 30 to 500 μηη, more preferably 100 to 300 μηη.

Normally, the membranes according to the invention and carrier membranes have an essentially circular, ellipsoid or rectangular diameter. Preferably, membranes according to the invention are essentially circular.

In one preferred embodiment, membranes according to the invention have a diameter (for essentially circular diameters), smaller diameter (for essentially ellipsoid diameters) or smaller feed size (for essentially rectangular diameters) of 2 to 10 mm, preferably 3 to 8 mm, more preferably 4 to 6 mm.

In another preferred embodiment, membranes according to the invention have a diameter (for essentially circular diameters), smaller diameter (for essentially ellipsoid diameters) or smaller feed size (for essentially rectangular diameters) of 2 to 4 mm.

In one embodiment the rejection layer is located on the inside of each channel of said multiple channel membrane

In one embodiment, the channels of a multibore membrane may incorporate an active layer with a pore size different to that of the carrier membrane or a coated layer forming the active layer. Suitable materials for the coated layer are polyoxazoline, polyethylene glycol, polystyrene, hy- drogels, polyamide, zwitterionic block copolymers, such as sulfobetaine or carboxybetaine. The active layer can have a thickness in the range from 10 to 500 nm, preferably from 50 to 300 nm, more preferably from 70 to 200 nm.

In one embodiment multibore membranes are designed with pore sizes between 0.2 and 0.01 μηη. In such embodiments the inner diameter of the capillaries can lie between 0.1 and 8 mm, preferably between 0.5 and 4 mm and particularly preferably between 0.9 and 1 .5 mm. The out- er diameter of the multibore membrane can for example lie between 1 and 26 mm, preferred 2.3 and 14 mm and particularly preferred between 3.6 and 6 mm. Furthermore, the multibore membrane can contain 2 to 94, preferably 3 to 19 and particularly preferred between 3 and 14 channels. Often multibore membranes contain seven channels. The permeability range can for ex- ample lie between 100 and 10000 L/m²hbar, preferably between 300 and 2000 L/m²hbar.

Typically multibore membranes of the type described above are manufactured by extruding a polymer, which forms a semi-permeable membrane after coagulation through an extrusion nozzle with several hollow needles. A coagulating liquid is injected through the hollow needles into the extruded polymer during extrusion, so that parallel continuous channels extending in extrusion direction are formed in the extruded polymer. Preferably the pore size on an outer surface of the extruded membrane is controlled by bringing the outer surface after leaving the extrusion nozzle in contact with a mild coagulation agent such that the shape is fixed without active layer on the outer surface and subsequently the membrane is brought into contact with a strong co- agulation agent. As a result a membrane can be obtained that has an active layer inside the channels and an outer surface, which exhibits no or hardly any resistance against liquid flow. Herein suitable coagulation agents include solvents and/or non-solvents. The strength of the coagulations may be adjusted by the combination and ratio of non-solvent/solvent. Coagulation solvents are known to the person skilled in the art and can be adjusted by routine experiments. An example for a solvent based coagulation agent is N-methylpyrrolidone. Non-solvent based coagulation agents are for instance water, iso-propanol and propylene glycol.

MF membranes are normally suitable for removing particles with a particle size of 0.1 μηη and above.

MF membranes normally have an average pore diameter of 0.05 μηη to 10 μηη, preferably 1 .0 μηη to 5 μηη. Microfiltration can use a pressurized system but it does not need to include pressure.

MF membranes can be capillaries, hollow fibers, flat sheet, tubular, spiral wound, pillows, hollow fine fiber or track etched. They are porous and allow water, monovalent species (Na+, CI-), dissolved organic matter, small colloids and viruses through but retain particles, sediment, algae or large bacteria.

Microfiltration systems are designed to remove suspended solids down to 0.1 micrometers in size, in a feed solution with up to 2-3% in concentration.

In one embodiment, MF membranes comprise as the main component at least polyamide (PA), polyvinylalcohol (PVA), Cellulose Acetate (CA), Cellulose Triacetate (CTA), CA-triacetate blend, Cellulose ester, Cellulose Nitrate, regenerated Cellulose, aromatic , aromatic/aliphatic or aliphatic Polyamide, aromatic, aromatic/aliphatic or aliphatic Polyimide, Polybenzimidazole (PBI), Polybenzimidazolone (PBIL), Polyacrylonitrile (PAN), PAN-poly(vinyl chloride) copolymer (PAN- PVC), PAN-methallyl sulfonate copolymer, Poly(dimethylphenylene oxide) (PPO), Polycarbonate, Polyester, Polytetrafluroethylene PTFE, Poly(vinylidene fluoride) (PVDF), Polypropylene (PP), Polyelectrolyte complexes, Poly(methyl methacrylate) PMMA, Polydimethylsiloxane (PDMS), aromatic, aromatic/aliphatic or aliphatic polyimide urethanes, aromatic, aromatic/aliphatic or aliphatic polyamidimides, crosslinked polyimides or polyarylene ether, polysul- fone, polyphenylenesulfone or polyethersulfone, or mixtures thereof in combination with at least one phenoxy resin P. In another embodiment of the invention, MF membranes comprise as the main component at least one polysulfone, polyphenylenesulfone and/or polyethersulfone in combination with at least one phenoxy resin P.

Membranes according to the invention comprise at least one polymer A, said polymer A being different from phenoxy resin P.

Preferably, said polymer A is a polyarylene ether, herein also referred to as polyarylene ether A. Preferably, membranes according to the invention comprise at least one polyarylene ether A. Suitable polyarylene ethers A are known as such to those skilled in the art and can be formed from polyarylene ether units of the general formula IV

with the following definitions: t, q: each independently 0, 1 , 2 or 3,

Q, T, Y: each independently a chemical bond or group selected from -0-, -S-, -SO2-, S=0, C=0, -N=N-, -CR^aR^b- where R^a and R^b are each independently a hydrogen atom or a C1-C12- alkyl, Ci-Ci2-alkoxy or C6-Ci8-aryl group, where at least one of Q, T and Y is not -0-, and at least one of Q, T and Y is -SO2-, and

Ar, Ar¹: each independently an arylene group having from 6 to 18 carbon atoms Polyarylene ethers are typically prepared by polycondensation of suitable starting compounds in dipolar aprotic solvents at elevated temperature (see, for example, R.N. Johnson et al., J.

Polym. Sci. A-1 5 (1967) 2375, J.E. McGrath et al., Polymer 25 (1984) 1827). Suitable polyarylene ethers A can be provided by reacting at least one starting compound of the structure X-Ar-Y (M1 ) with at least one starting compound of the structure HO-Ar¹-OH (M2) in the presence of a solvent (L) and of a base (B), where

Y is a halogen atom,

- X is selected from halogen atoms and OH, preferably from halogen atoms, especially F, CI or Br, and

Ar and Ar¹ are each independently an arylene group having 6 to 18 carbon atoms. In one embodiment, a polyarylene ether A which is formed from units of the general formula IV with the definitions as above is provided in the presence of a solvent (L):

If Q, T or Y, with the abovementioned prerequisites, is a chemical bond, this is understood to mean that the group adjacent to the left and the group adjacent to the right are bonded directly to one another via a chemical bond. Preferably, Q, T and Y in formula (IV), however, are independently selected from -O- and -SO2-, with the proviso that at least one of the group consisting of Q, T and Y is -SO2-.

When Q, T or Y are -CR^aR^b-, R^a and R^b are each independently a hydrogen atom or a C1-C12- alkyl, Ci-Ci2-alkoxy or C6-Ci8-aryl group.

Preferred Ci-Ci2-alkyl groups comprise linear and branched, saturated alkyl groups having from 1 to 12 carbon atoms. Particularly preferred Ci-Ci2-alkyl groups are: Ci-C6-alkyl radicals such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, 2- or 3-methylpentyl and longer-chain radicals such as unbranched heptyl, octyl, nonyl, decyl, undecyl, lauryl, and the singularly or multiply branched analogs thereof.

Useful alkyl radicals in the aforementioned usable Ci-Ci2-alkoxy groups include the alkyl groups having from 1 to 12 carbon atoms defined above. Cycloalkyl radicals usable with preference comprise especially C3-Ci2-cycloalkyl radicals, for example cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclopropylmethyl, cyclopropylethyl, cyclopropylpropyl, cyclobutylmethyl, cyclobutylethyl, cyclpentylethyl, -propyl, -butyl, -pentyl, -hexyl,

cyclohexylmethyl, -dimethyl, -trimethyl.

Ar and Ar¹ are each independently a C6-Ci8-arylene group. Proceeding from the starting materials described below, Ar is preferably derived from an electron-rich aromatic substance which is preferably selected from the group consisting of hydroquinone, resorcinol,

dihydroxynaphthalene, especially 2,7-dihydroxynaphthalene, and 4,4'-bisphenol. Ar¹ is preferably an unsubstituted C6- or Ci2-arylene group. Useful C6-Ci8-arylene groups Ar and Ar¹ are especially phenylene groups, such as 1 ,2-, 1 ,3- and 1 ,4-phenylene, naphthylene groups, for example 1 ,6-, 1 ,7-, 2,6- and 2,7-naphthylene, and the arylene groups derived from anthracene, phenanthrene and naphthacene.

Preferably, Ar and Ar¹ in the preferred embodiments of the formula (IV) are each independently selected from the group consisting of 1 ,4-phenylene, 1 ,3-phenylene, naphthylene, especially 2,7-dihydroxynaphthalene, and 4,4'-bisphenylene.

Units present with preference within the polyarylene ether are those which comprise at least one of the following repeat structural units IVa to IVo:

In addition to the units IVa to IVo present with preference, preference is also given to those units in which one or more 1 ,4-dihydroxyphenyl units are replaced by resorcinol or

dihydroxynaphthalene units.

Particularly preferred units of the general formula II are units IVa, IVg and IVk. It is also particularly preferred when the polyarylene ethers A are formed essentially from one kind of units of the general formula IV, especially from one unit selected from IVa, IVg and IVk.

In a particularly preferred embodiment, Ar = 1 ,4-phenylene, t = 1 , q = 0, T = SO2 and Y = SO2. Such polyarylene ethers are referred to as polyether sulfone (PESU).

Suitable polyarylene ethers A preferably have a mean molecular weight Mn (number average) in the range from 2000 to 70000 g/mol, especially preferably 5000 to 40000 g/mol and particularly preferably 7000 to 30000 g/mol. The average molecular weight of the polyarylene ethers can be controlled and calculated by the ratio of the monomers forming the polyarylene ethers, as described by H.G. Elias in "An Introduction to Polymer Science" VCH Weinheim, 1997, p. 125.

Suitable starting compounds are known to those skilled in the art and are not subject to any fundamental restriction, provided that the substituents mentioned are sufficiently reactive within a nucleophilic aromatic substitution. Preferred starting compounds are difunctional. "Difunctional" means that the number of groups reactive in the nucleophilic aromatic substitution is two per starting compound. A further criterion for a suitable difunctional starting compound is a sufficient solubility in the solvent, as explained in detail below.

Preference is given to monomeric starting compounds, which means that the reaction is preferably performed proceeding from monomers and not proceeding from prepolymers.

The starting compound (M1 ) used is preferably a dihalodiphenyl sulfone. The starting compound (M2) used is preferably dihydroxydiphenyl sulfone.

Suitable starting compounds (M1 ) are especially dihalodiphenyl sulfones such as 4,4'- dichlorodiphenyl sulfone, 4,4'-difluorodiphenyl sulfone, 4,4'-dibromodiphenyl sulfone, bis(2- chlorophenyl) sulfones, 2,2'-dichlorodiphenyl sulfone and 2,2'-difluorodiphenyl sulfone, particular preference being given to 4,4'-dichlorodiphenyl sulfone and 4,4'-difluorodiphenyl sulfone.

Preferred compounds (M2) are accordingly those having two phenolic hydroxyl groups.

Phenolic OH groups are preferably reacted in the presence of a base in order to increase the reactivity toward the halogen substituents of the starting compound (M1 ).

Preferred starting compounds (M2) having two phenolic hydroxyl groups are selected from the following compounds: dihydroxybenzenes, especially hydroquinone and resorcinol;

dihydroxynaphthalenes, especially 1 ,5-dihydroxynaphthalene, 1 ,6- dihydroxynaphthalene, 1 ,7-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene;

dihydroxybiphenyls, especially 4,4'-biphenol and 2,2'-biphenol;

bisphenyl ethers, especially bis(4-hydroxyphenyl) ether and bis(2-hydroxyphenyl) ether; bisphenylpropanes, especially 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4- hydroxyphenyl)propane and 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane;

bisphenylmethanes, especially bis(4-hydroxyphenyl)methane;

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

bisphenyl sulfides, especially bis(4-hydroxyphenyl) sulfide;

bisphenyl ketones, especially bis(4-hydroxyphenyl) ketone;

bisphenylhexafluoropropanes, especially 2,2-bis(3,5-dimethyl-4- hydroxyphenyl)hexafluoropropane; and

bisphenylfluorenes, especially 9,9-bis(4-hydroxyphenyl)fluorene;

1 ,1 -Bis(4-hydroxyphenyl)-3,3,5-trimethyl-cyclohexane (bisphenol TMC). It is preferable, proceeding from the aforementioned aromatic dihydroxyl compounds (M2), by addition of a base (B), to prepare the dipotassium or disodium salts thereof and to react them with the starting compound (M1 ). The aforementioned compounds can additionally be used individually or as a combination of two or more of the aforementioned compounds.

Hydroquinone, resorcinol, dihydroxynaphthalene, especially 2,7-dihydroxynaphthalene, bisphenol A, dihydroxydiphenyl sulfone and 4,4'-bisphenol are particularly preferred as starting compound (M2).

However, it is also possible to use trifunctional compounds. In this case, branched structures are the result. If a trifunctional starting compound (M2) is used, preference is given to 1 ,1 ,1 - tris(4-hydroxyphenyl)ethane.

The ratios to be used derive in principle from the stoichiometry of the polycondensation reaction which proceeds with theoretical elimination of hydrogen chloride, and are established by the person skilled in the art in a known manner.

Preferably, the conversion in the polycondensation is at least 0.9, which ensures a sufficiently high molecular weight. Solvents (L) preferred in the context of the present invention are organic, especially aprotic polar solvents. Suitable solvents also have a boiling point in the range from 80 to 320°C, especially 100 to 280°C, preferably from 150 to 250°C. Suitable aprotic polar solvents are, for example, high-boiling ethers, esters, ketones, asymmetrically halogenated hydrocarbons, anisole, dimethylformamide, dimethyl sulfoxide, sulfolane, N-methyl-2-pyrrolidone and/or N- ethyl-2-pyrrolidone. It is also possible to use mixtures of these solvents.

A preferred solvent is especially N-methyl-2-pyrrolidone and/or N-ethyl-2-pyrrolidone.

Preferably, the starting compounds (M1 ) and (M2) are reacted in the aprotic polar solvents (L) mentioned, especially N-methyl-2-pyrrolidone.

In a preferred embodiment the starting compounds (M1 ) and (M2) are reacted in the presence of a base (B). The bases are preferably anhydrous. Suitable bases are especially anhydrous alkali metal and/or alkaline earth metal carbonate, preferably sodium carbonate, potassium carbonate, calcium carbonate or mixtures thereof, very particular preference being given to potassium carbonate, especially potassium carbonate with a volume-weighted mean particle size of less than 200 micrometers, determined with a particle size measuring instrument in a suspension of N-methyl-2-pyrrolidone. A particularly preferred combination is N-methyl-2-pyrrolidone as solvent (L) and potassium carbonate as base (B). The reaction of the suitable starting compounds (M1 ) and (M2) is performed at a temperature of 80 to 250°C, preferably 100 to 220°C, the upper temperature limit being determined by the boiling point of the solvent. The reaction is effected preferably within a time interval of 2 to 12 h, especially of 3 to 8 h.

Especially suitable starting materials, bases, solvents, ratios of all components involved, reaction times and reaction parameters like temperatures and pressures as well as suitable workup procedures are for example disclosed in US 4,870,153, col. 4, In. 1 1 to col. 17, In. 64, EP 1 13 1 12, p. 6, In. 1 to p. 9, In. 14, EP-A 297 363, p. 10, In. 38 to p. 1 1 , In. 24, EP-A 135 130, p. 1 , In. 37 to p. 4, In. 20, which are incorporated in this application by reference.

Phenoxy resins are polymers that are obtained by reacting a diol and epichlorohydrin. Such reaction products are herein also referred to as the phenoxy backbone of phenoxy resins P. Phenoxy resins P comprise a phenoxy backbone and at least one hydrophilic side chain. Phenoxy resins P may further comprise additional functional groups or side chains of a different nature.

Suitable phenoxy backbones of phenoxy resins P and their synthesis are for example disclosed in US 3,305,528, on col. 1 , In. 64 to col. 9, In. 48, which is included in this application by reference.

Preferred diols for making phenoxy resins are bisphenols. Preferred bisphenols are 2,2-Bis(4- hydroxyphenyl)propane (Bisphenol A), 1 ,1 -Bis(4-hydroxyphenyl)-1 -phenyl-ethane (Bisphenol AP), 2,2-Bis(4-hydroxyphenyl)hexafluoropropane (Bisphenol AF), 2,2-Bis(4- hydroxyphenyl)butane (Bisphenol B), Bis-(4-hydroxyphenyl)diphenylmethane (Bisphenol BP), 2,2-Bis(3-methyl-4-hydroxyphenyl)propane (Bisphenol C), Bis(4-hydroxyphenyl)-2,2- dichlorethylene (also called Bisphenol C), 1 ,1 -Bis(4-hydroxyphenyl)ethane (Bisphenol E), Bis(4- hydroxydiphenyl)methane (Bisphenol F), 2,2-Bis(4-hydroxy-3-isopropyl-phenyl)propane (Bisphenol G), 1 ,3-Bis(2-(4-hydroxyphenyl)-2-propyl)benzene (Bisphenol M), Bis(4- hydroxyphenyl)sulfone (Bisphenol S), 1 ,4-Bis(2-(4-hydroxyphenyl)-2-propyl)benzene (Bisphenol P), 5,5' -(1 -Methylethyliden)-bis[1 ,1 '-(bisphenyl)-2-ol]propane (Bisphenol PH), 1 ,1 -Bis(4- hydroyphenyl)-3,3,5-trimethyl-cyclohexane (Bisphenol TMC), 1 ,1 -Bis(4-hydroxyphenyl)- cyclohexane (Bisphenol Z). Preferred diols for making phenoxy resin are bisphenol A, bisphenol F and bisphenol S. In one preferred embodiment, the phenoxy backbone of phenoxy resins P is obtained from bi- sphenol A and epichlorohydrin and has a structure according to formula (I):

(I),

with n having a value of 10 to 200, preferably 20 to 100, more preferably 30 to 90, even more preferably 40 to 80.

Phenoxy resins P that are useful according to the invention for making membranes comprise at least one hydrophilic side chain. Preferably such hydrophilic side chains have a solubility in water at 23°C of 5 g/l, preferably 10 g/l, more preferably 20 g/l, even more preferably 100 g/l. The solubility in water of such hydrophilic side chains is determined by measuring the solubility of said side chain in the absence of the phenoxy backbone, side chain in the absence of the phenoxy backbone being OH terminated at the position that is bound to the phenoxy backbone in phenoxy resin P. Preferably, said hydrophilic side chain comprises ionic groups or polyalkylene oxides. In the context of this application, hydrophilic side chains comprising ionic groups and/or polyalkylene oxides are always considered suitable hydrophilic side chains with a solubility in water of more tan 5 g/l at 23°C. Preferably, 1 to 50 mol% of the hydroxy groups of the phenoxy backbone are covalently bound to hydrophilic side chains.

In one embodiment, said hydrophilic side chains comprise ionic groups selected from sulfonic groups and carboxylic groups.

In one embodiment, phenoxy resin P comprises a phenoxy backbone, onto which one or more ethylenically unsaturated monomers like (meth)acrylic acid and/or (meth)acrylic ester have been grafted. Water dispersible phenoxy resins obtained by grafting of ethylenically unsaturated monomers are for example disclosed in US 4,355,122 col. 1 , In 44 to col. 7, In. 17, which is included herein by reference.

In one embodiment, phenoxy resins P comprise a phenoxy backbone, in which 3 to 50 mol% of the pendant hydroxy groups have been reacted to produce moieties having pendant carboxylic groups. In one embodiment, phenoxy resins P comprise a phenoxy backbone, in which 3 to 50 mol% of the pendant hydroxy groups have been reacted with carboxylic acid anhydrides like succinic anhydride, trimellitic anhydride, tetrahydrophthalic anhydride, to produce moieties hav- ing pendant carboxylic groups. Suitable phenoxy resins comprising a phenoxy backbone and hydrophilic side chains comprising carboxylic groups are for example disclosed in US

4,638,038, col 2, In 56 to col. 9, In. 65, which is included in this application by reference.

In one embodiment, said hydrophilic side chains comprise polyalkyleneoxide composed substantially of oxyalkylene units. Oxyalkylene units are units of the general formula -R¹-0-. In this formula R¹ is a divalent aliphatic hydrocarbon radical which may also, optionally, have further substituents. Additional substituents on the radical R¹ may comprise, in particular, O-containing groups, examples being OH groups.

The oxyalkylene units may in particular be -(CH₂)₂-0- -(CH₂)₃-0-, -(CH₂)₄-0-, -CH₂-CH(R²)- 0-, -CH₂-CHOR³-CH₂-0- with R² being an alkyl group, especially Ci-C₂₄ alkyl, or an aryl group, especially phenyl, and R³ being a group selected from the group consisting of hydrogen, Ci-C₂₄ alkyl, R -C(=0)-, and R -NH-C(=0)-.

The hydrophilic side chains may also comprise further structural units, such as ester groups carbonate groups or amino groups, for example. They may additionally comprise the starter molecules used at the start of the polymerization, or fragments thereof. Examples comprise terminal groups R²-0-, where R² is as defined above.

As a general rule the hydrophilic side chains comprise ethylene oxide units -(CH₂)₂-0- and/or propylene oxide units -CH₂-CH(CH3)-0, as main components, while higher alkylene oxide units, i.e. those having more than 3 carbon atoms, are present only in small amounts in order to fine- tune the properties. The hydrophilic side chains may be random copolymers, gradient copoly- mers, alternating or block copolymers comprising ethylene oxide and propylene oxide units. The amount of higher alkylene oxide units ought not to exceed 10% by weight, preferably 5% by weight. The hydrophilic side chains in question are preferably blocks comprising at least 50% by weight of ethylene oxide units, preferably 75% by weight, and more preferably at least 90% by weight of ethylene oxide units. With very particular preference the hydrophilic side chains in question are pure polyoxyethylene blocks.

The hydrophilic side chains are obtainable in a manner known in principle, for example, by polymerizing alkylene oxides and/or cyclic ethers having at least 3 carbon atoms and also, optionally, further components. They may additionally be prepared by polycondensing dialcohols and/or polyalcohols, suitable starters, and also, optionally, further monomeric components.

Examples of suitable alkylene oxides as monomers for the hydrophilic blocks comprise ethylene oxide and propylene oxide and also 1 -butene oxide, 2,3-butene oxide, 2-methyl-1 ,2-propene oxide (isobutene oxide), 1 -pentene oxide, 2,3-pentene oxide, 2-methyl-1 ,2-butene-oxide, 3- methyl-1 ,2-butene oxide, 2,3-hexene oxide, 3,4-hexene oxide, 2-methyl-1 ,2-pentene oxide, 2- ethyl-1 ,2-butene oxide, 3-methyl-1 ,2-pentene oxide, decene oxide, 4-methyl-1 ,2-pentene oxide, styrene oxide, or be formed from a mixture of oxides of industrially available raffinate streams. Examples of cyclic ethers comprise tetrahydrofuran. It is of course also possible to use mixtures of different alkylene oxides. The skilled worker makes an appropriate selection from among the monomers and further components in accordance with the desired properties of the hydrophilic side chain and the phenoxy resin P.

The hydrophilic side chains may also be branched or star-shaped. Blocks of this kind are obtainable by using starter molecules having at least 3 arms. Examples of suitable starters comprise glycerol, trimethylolpropane, pentaerythritol or ethylenediamine. In one embodiment, polyalkylene oxide blocks are homopolymers of one alkylene oxide, preferably ethylene oxide.

In one preferred embodiment, phenoxy resins P have a structure according to formula (II):

_{(| | ) i} wherein

o + p = 10 to 200, preferably 20 to 100, more preferably 30 to 90, even more preferably 40 to 80;

o : (o+p) = 0.05 to 1 , preferably 0.1 to 99, more preferably 0.2 to 0.9, even more preferably 0.3 to 0.7 end especially preferably 0.35 to 0.6;

m = 2 to 200, preferably 3 to 100, more preferably 5 to 80,

E is a suitable end group. o : (o+p) is the molar ratio of alkoxylated repeating units to the sum of all repeating units in formula (II).

In formula (II) is it is to be understood that m may have a different value in every repeating unit. Also, not every repeating unit has to be alkoxylated.

Suitable end groups E for the alkylene oxide side chain are for example H or alkyl groups like methyl.

Phenoxy resin P comprises repeating units with the index o and p.

Phenoxy resin P can comprise repeating units with the index o and p statistically distributed or as blocks. Preferably phenoxy resin P is a statistical polymer of repeating units with the index o and p in formula (II). The end groups in phenoxy backbone are not essential to the invention and can for example be H or alkyl groups like methyl groups.

The synthesis of the phenoxy resins P can in one embodiment be performed by first separately preparing a polyalkylene oxide and reacting it in a polymer-analogous reaction with the phenoxy backbone.

In a preferred embodiment, suitable hydrophilic side chains are obtained by alkoxylation, especially ethoxylation of the phenoxy backbone.

Thus, preferably, phenoxy resins P are not endcapped at the polyalkylene oxide side chain, corresponsing to phenoxy resins according to formula (III).

(HI)

However, in a less preferred embodiment it is also possible to subject phenoxy resins to an endcapping reaction, for example with alkyl groups like methyl groups.

In one embodiment, phenoxy resin P comprises a polyester modified phenoxy backbone. In one embodiment, phenoxy resin P comprises a phenoxy backbone that -OH groups of which have at least partly been grafted with caprolactone to obtain a polyester modified phenoxy backbone.

In case phenoxy resins P comprise hydrophilic side chains comprising polyalkylene oxide, such phenoxy resins P comprise 5 to 85 % by weight of polyalkylene oxide groups, based on the mass of the phenoxy resin P, preferably 20 to 80, more preferably 30 to 60 % by weight. Preferably, phenoxy resins P in membranes according to the invention have an average molecular mass Mw of 5000 to 500.000, preferably 10000 to 250000, more preferably 25.000 to 100000 g/mol.

Normally, membranes according to the invention comprise said at least one phenoxy resin P in an amount of 0.01 % by weight to 20 % by weight, preferably 0.1 to 15, more preferably 1 to 10 % by weight.

Normally membranes according to the invention comprise said at least one polymer A and said at least one phenoxy resin P as a mixture (a blend).

Normally membranes according to the invention comprise said at least one polymer A and said at least one phenoxy resin P in the same layer of said membrane. In one embodiment, membranes according to the invention comprise said at least one polymer A and said at least one phenoxy resin P as a homogenous mixture.

In one embodiment, membranes according to the invention comprise said at least one polymer A and said at least one phenoxy resin P in the same layer of said membrane, wherein said at least one phenoxy resin P is enriched on the surface of said membrane. "Surface" in this context is understood to mean the top layer of the surface with a depth of 10 nm.

Another aspect of the invention are processes for making membranes comprising at least one polyarylene ether A and at least one phenoxy resin P, wherein said phenoxy resin P comprises at least one hydrophilic side chain.

In one embodiment membranes according to the invention are made by including at least one phenoxy resin P in the dope solution comprising the membrane material and by coagulation said dope solution with the help of a suitable coagulant. Suitable coagulants can for example comprise water and/or alcohols.

Membranes according to the invention have a high flexibility.

Furthermore, membranes according to the invention show a low contact angle when contacted with water. Thus, membranes according to the invention are easily wettable with water.

Membranes according to the invention have a high upper glass transition temperature.

Membranes according to the invention are easy to make and to handle, are able to stand high temperatures and can for example be subjected to vapor sterilization.

Furthermore, membranes according to the invention have very good dimensional stabilities, high heat distortion resistance, good mechanical properties and good flame retardance properties and biocompatibility. They can be processed and handled at high temperatures, enabling the manufacture of membranes and membrane modules that are exposed to high temperatures and are for example subjected to disinfection using steam, water vapor or higher temperatures, for example above 100°C of above 125 °C.

Membranes according to invention show excellent properties with respect to the decrease of flux through a membrane over time and their fouling and biofouling properties.

Membranes according to the invention are easy and economical to make.

Filtration systems and membranes according to invention can be made using aqueous or alcoholic systems and are thus environmentally friendly. Furthermore, leaching of toxic substances is not problematic with membranes according to the invention.

Membranes according to the invention have a long lifetime. Another aspect of the invention are membrane elements comprising a copolymer according to the invention.

A "membrane element", herein also referred to as a "filtration element", shall be understood to mean a membrane arrangement of at least one single membrane body. A filtration element can either be directly used as a filtration module or be included in a membrane module. A membrane module, herein also referred to as a filtration module, comprises at least one filtration element. A filtration module normally is a ready to use part that in addition to a filtration element comprises further components required to use the filtration module in the desired application, such as a module housing and the connectors. A filtration module shall thus be understood to mean a single unit which can be installed in a membrane system or in a membrane treatment plant. A membrane system herein also referred to as a filtration system is an arrangement of more than one filtration module that are connected to each other. A filtration system is implemented in a membrane treatment plant. In many cases, filtration elements comprise more than one membrane arrangement and may further comprise more components like an element housing, one or more bypass tubes, one or more baffle plates, one or more perforated inner tubes or one or more filtrate collection tube. For hollow fiber or multibore membranes, for example, a filtration element normally comprises more than one hollow fiber or multibore membrane arrangement that have been fixed to an out- er shell or housing by a potting process. Filtration elements that have been subjected to potting can be fixed on one end or on both ends of the membrane arrangement to the outer shell or housing.

In one embodiment, filtration elements or filtration modules according to the invention discharge permeate directly through an opening in the tube housing or indirectly through a discharge tube located within the membrane element. Particularly when indirect discharge is facilitated the discharge tube can for example be placed in the center of the membrane element and the capillaries of the membrane element are arranged in bundles surrounding the discharge tube.

In another embodiment, a filtration element for filtering comprises an element housing, wherein at least one membrane arrangement and at least one permeate collecting tube are arranged within the element housing and wherein the at least one permeate collecting tube is arranged in an outer part of the filtration element.

The permeate collecting tube inside filtration elements or filtration modules may in one embodiment have cylindrical shape, wherein the cross-section may have any shape such as round, oval, triangular, square or some polygon shape. Preferred is a round shape, which leads to enhanced pressure resistance. Preferably the longitudinal center line of the at least one permeate collecting tube is arranged parallel to the longitudinal center line of the membrane element and the element housing. Furthermore, a cross-section of the permeate collecting tube may be chosen according to the permeate volume produced by the membrane element and pressure loss- es occurring in the permeate collecting tube. The diameter of the permeate collecting tube may be less than half, preferred less than a third and particularly preferred less than a quarter of the diameter of the element housing. The permeate collecting tube and the membrane element may have different or the same shape. Preferably the permeate collecting tube and the membrane element have the same shape, particularly a round shape. Thus, the at least one permeate collecting tube can be arranged within the circumferential ring extending from the radius of the element housing to half, preferred a third and particularly preferred a quarter of the radius of the element housing.

In one embodiment the permeate collecting tube is located within the filtration element such that the permeate collecting tube at least partially touches the element housing. This allows placing the filtration element in the filtration module or system such that the permeate collecting tube is arranged substantially at the top of the filtration element in horizontal arrangement. In this con- text substantially at the top includes any position in the outer part of the membrane that lies within ±45°, preferred ±10° from a vertical center axis in a transverse plane of the filtration element. Here the vertical center axis in a transverse plane is perpendicular to the horizontal center axis in the transverse plane and to the longitudinal center axis extending along the long axis of the filtration element. By arranging the permeate collecting tube this way, air residing within the membrane element before start-up of the filtration module or system can be collected in the permeate collecting tube, which can then easily be vented upon start up by starting the filtration operation. In particular, air pockets can be displaced by permeate which is fed to the filtration module or system and filtered by the membrane element on start up. By releasing air from the filtration module or system the active area of the membrane element increases, thus increasing the filtering effect. Furthermore the risk of fouling due to trapped air pockets decreases and pressure surges as well as the risk of breakage of the membrane element are minimized.

In another embodiment of the filtration element at least two permeate collecting tubes may be arranged in the filtration element, particularly within the element housing. By providing more than one permeate collecting tube the output volume of permeate at a constant pressure can be increased and adjusted to the permeate volume produced by the membrane element. Furthermore the pressure loss is reduced if high backwashing flows are required. Here at least one first permeate collecting tube is arranged in the outer part of the filtration element and at least one second permeate collecting tube can be arranged in the inner or the outer part of the filtration element. For example, two permeate collecting tubes may be arranged in the outer part or one first permeate collecting tube may be arranged in the outer part and another second permeate collecting tube may be arranged in the inner part of the filtration element.

Preferably at least two permeate collecting tubes are arranged opposite each other in the outer part or the outer circumferential ring of the filtration element. By providing at least two permeate collecting tubes opposite each other in the outer part of the filtration element, the filtration element can be placed in a filtration module or system such that one of the tubes are arranged substantially at the top of the element while the other tube is arranged substantially at the bottom. This way ventilation can be achieved through the top tube, while the additional bottom tube increases output volume at a constant pressure. In another embodiment the filtration element further comprises a perforated tube arranged around the membrane element, in particular composing at least one membrane arrangement comprising at least one hollow fiber membrane. The perforations may be formed by holes or other openings located in regular or irregular distances along the tube. Preferably, the membrane element, in particular the membrane arrangement is enclosed by the perforated tube. With the perforated tube the axial pressure distribution along the filtration element can be equalized in filtration and back washing operation. Thus, the permeate flow is evenly distributed along the filtration element and hence the filtering effect can be increased.

In another embodiment the perforated tube is arranged such that an annular gap is formed be- tween the element housing and the perforated tube. Known membrane elements do not have a distinct border and the membrane element are directly embedded in a housing of the filtration element. This leads to an uneven pressure distribution in axial direction as the axial flow is disturbed by the membrane element. In another embodiment the membrane element comprises multibore membranes. The multibore membranes preferably comprise more than one capillary, which runs in a channel along the longitudinal axis of the membrane element or the filtration element. Particularly, the multibore membrane comprises at least one substrate forming the channels and at least one active layer arranged in the channels forming the capillaries. Embedding the capillaries within a substrate allows forming a multibore membrane, which are considerably easier to mount and mechanically more stable than membranes based on single hollow fibers. As a result of the mechanical stability, the multibore membrane is particularly suitable for cleaning by back washing, where the filtration direction is reversed such that a possible fouling layer formed in the channels is lifted and can be removed. In combination with the arrangements of the permeate colleting tube leading to an even pressure distribution within the membrane element, the overall performance and stability of the filtration element is further enhanced.

In contrast to designs with a central discharge tube and single bore membranes, the distribution of the multibore membranes is advantageous in terms of producing lower pressure loss in both operational modes filtration and backwash. Such designs further increases stability of the capillaries by equalizing the flow or pressure distribution across the membrane element. Thus, such designs avoid adverse effects on the pressure distribution among the capillaries of the membrane element. For designs with a central permeate collecting tube permeate flows in filtration mode from the outer capillaries of the membrane to the inner capillaries and has to pass a de- creasing cross-section. In backwashing mode the effect reverses in that sense, that the flow volume decreases towards the outer capillaries and thus the cleaning effect decreases towards the outside as well. In fact the uneven flow and pressure distribution within the membrane ele- ment leads to the outer capillaries having a higher flow in filtration mode and hence building up more fouling layer than the inner capillaries. In backwashing mode, however, this reverses to the contrary with a higher cleaning effect for the inner capillaries, while the outer exhibit a higher build up. Thus the combination of the permeate collecting tube in the outer part of the filtration element and the use of the multi-bore membrane synergistically lead to a higher long-term stability of the filtration element.

Another aspect of the invention are membrane modules comprising membranes or membrane elements according to the invention.

In one embodiment, membrane modules according to the invention comprise a filtration element which is arranged within a module housing. The raw water is at least partly filtered through the filtration element and permeate is collected inside the filtration module and removed from the filtration module through an outlet. In one embodiment the filtrate (also referred to as "permeate") is collected inside the filtration module in a permeate collection tube. Normally the element housing, optionally the permeate collecting tube and the membrane arrangement are fixed at each end in membrane holders comprising a resin, preferably an epoxy resin, in which the filtration element housing, the membranes, preferably multibore membranes, and optionally the fil- trate collecting tube are embedded.

Membrane modules can in one embodiment for example have cylindrical shape, wherein the cross-section can have any shape such as round, oval, triangular, square or some polygon shape. Preferred is a round shape, which leads to a more even flow and pressure distribution within the membrane element and avoids collection of filtered material in certain areas such as corners for e.g. square or triangular shapes.

In one embodiment, membrane modules according to the invention have an inside-out configuration ("inside feed") with the filtrate flowing from the inside of a hollow fiber or multibore membrane to the outside.

In one embodiment, membrane modules according to the invention have an outside-in filtration configuration ("outside feed").

In a preferred embodiment, membranes, filtration elements, filtration modules and filtration sys- terns according to the invention are configured such that they can be subjected to backwashing operations, in which filtrate is flushed through membranes in opposite direction to the filtration mode.

In one embodiment, membrane modules according to the invention are encased.

In another embodiment, membrane modules according to the invention are submerged in the fluid that is to be subjected to filtration. In one embodiment, membranes, filtration elements, filtration modules and filtration systems according to the invention are used in membrane bioreactors.

In one embodiment, membrane modules according to the invention have a dead-end configura- tion and/or can be operated in a dead-end mode.

In one embodiment, membrane modules according to the invention have a crossflow configuration and/or can be operated in a crossflow mode.

In one embodiment, membrane modules according to the invention have a directflow configuration and/or can be operated in a directflow mode.

In one embodiment, membrane modules according to the invention have a configuration that allow the module to be cleaned and scoured with air.

In one embodiment, filtration modules include a module housing, wherein at least one filtration element as described above is arranged within the module housing. Hereby the filtration element is arranged vertically or horizontally. The module housing is for instance made of fiber reinforced plastic (FRP) or stainless steel.

In one embodiment the at least one filtration element is arranged within the module housing such that the longitudinal center axis of the filtration element and the longitudinal center axis of the housing are superimposed. Preferably the filtration element is enclosed by the module housing, such that an annular gap is formed between the module housing and the element housing. The annular gap between the element housing and the module housing in operation allow for an even pressure distribution in axial direction along the filtration module.

In another embodiment the filtration element is arranged such that the at least one permeate collecting tube is located substantially at the top of the filtration module or filtration element. In this context substantially at the top includes any position in the outer part of the membrane element that lies within ±45°, preferred ±10°, particularly preferred ±5° from a vertical center axis in a transverse plane of the filtration element. Furthermore, the vertical center axis in a transverse plane is perpendicular to the horizontal center axis in the transverse plane and to the longitudinal center axis extending along the long axis of the filtration element. By arranging the permeate collecting tube this way, air residing within the filtration module or system before start up can be collected in the permeate collecting tube, which can then easily be vented upon start up by starting the filtration operation. In particular, air pockets can be displaced by permeate, which is fed to the filtration module or system on start up. By releasing air from the filtration module or system the active area of the membrane element is increased, thus increasing the filtering effect. Furthermore, the risk of fouling due to trapped air pockets decreases. Further preferred the filtration module is mount horizontally in order to orientate the permeate collecting tube accord- ingly. In another embodiment the filtration element is arranged such that at least two permeate collecting tubes are arranged opposite each other in the outer part of the filtration element. In this embodiment the filtration module can be oriented such that one of the permeate collecting tubes are arranged substantially at the top of the filtration element, while the other tube is arranged substantially at the bottom of the filtration element. This way the ventilation can be achieved through the top tube, while the bottom tube allows for a higher output volume at a constant pressure. Furthermore, the permeate collecting tubes can have smaller dimensions compared to other configurations providing more space to be filled with the membrane element and thus increasing the filtration capacity.

In one embodiment, membrane modules according to the invention can have a configuration as disclosed in WO 2010/121628, S. 3, Z. 25 to p. 9, In 5 and especially as shown in Fig. 2 and Fig.3 of WO 2010/121628.

In one embodiment membrane modules according to the invention can have a configuration as disclosed in EP 937 492, [0003] to [0020].

In one embodiment membrane modules according to the invention are capillary filtration mem- brane modules comprising a filter housing provided with an inlet, an outlet and a membrane compartment accommodating a bundle of membranes according to the invention, said membranes being cased at both ends of the membrane module in membrane holders and said membrane compartment being provided with discharge conduits coupled to the outlet for the conveyance of the permeate. In one embodiment said discharge conduits comprise at least one discharge lamella provided in the membrane compartment extending substantially in the longitudinal direction of the filtration membranes.

Another aspect of the invention are filtration systems comprising membrane modules according to the invention. Connecting multiple filtration modules normally increases the capacity of the filtration system. Preferably the filtration modules and the encompassed filtration elements are mounted horizontally and adapters are used to connect the filtration modules accordingly.

In one embodiment, filtration systems according to the invention comprise arrays of modules in parallel.

In one embodiment, filtration systems according to the invention comprise arrays of modules in horizontal position.

In one embodiment, filtration systems according to the invention comprise arrays of modules in vertical position.

In one embodiment, filtration systems according to the invention comprise a filtrate collecting vessel (like a tank, container).

In one embodiment, filtration systems according to the invention use filtrate collected in a filtrate collecting tank for backwashing the filtration modules. In one embodiment, filtration systems according to the invention use the filtrate from one or more filtration modules to backwash another filtration module.

In one embodiment, filtration systems according to the invention comprise a filtrate collecting tube.

In one embodiment, filtration systems according to the invention comprise a filtrate collecting tube to which pressurized air can be applied to apply a backwash with high intensity.

In one embodiment, filtration systems according to the invention have a configuration as disclosed in EP 1 743 690, col. 2, In. 37 to col. 8, In. 14 and in Fig. 1 to Fig. 1 1 of EP 1 743 690; EP 2 008 704, col. 2, In. 30 to col. 5, In. 36 and Fig. 1 to Fig. 4; EP 2 158 958, col. 3, In. 1 to col. 6, In. 36 and fig. 1 .

In one embodiment filtration systems according to the invention comprise more than one filtration modules arranged vertically in a row, on both of whose sides an inflow pipe is arrayed for the fluid to be filtered and which open out individually allocated collecting pipes running lengthwise per row, whereby each filtration module has for the filtrate at least one outlet port which empties into a filtrate collecting pipe, whereby running along the sides of each row of filtration modules is a collecting pipe that has branch pipes allocated to said pipe on each side of the filtration module via which the allocated filtration module is directly connectable, wherein the filtrate collecting pipe runs above and parallel to the upper two adjacent collecting pipes.

In one embodiment, filtration systems according to the invention comprise a filtrate collecting pipe that is connected to each of the filtration modules of the respective filtration system and that is designed as a reservoir for backwashing the filtration system, wherein the filtration system is configured such that in backwashing mode pressurized air is applied to the filtrate collect- ing pipe to push permeate water from the permeate collecting pipe through the membrane modules in reverse direction.

In one embodiment, filtration systems according to the invention comprise a plurality of module rows arranged in parallel within a module rack and supplyable with raw water through sup- ply/drain ports and each end face via respectively associated supply/drain lines and each including a drain port on a wall side for the filtrate, to which a filtrate collecting line is connected for draining the filtrate, wherein valve means are provided to control at least one filtration and backwashing mode, wherein, in the backwashing mode, a supply-side control valve of the first supply/drain lines carrying raw water of one module row is closed, but an associated drain-side control valve of the other supply/drain line of one module row serving to drain backwashing water is open, whereas the remaining module rows are open, to ensure backwashing of the one module row of the module rack by the filtrate simultaneously produced by the other module rows. Hereinafter, when reference is made to the use of "membranes" for certain applications, this shall include the use of the membranes as well as filtration elements, membrane modules and filtration systems comprising such membranes and/or membrane modules. In a preferred embodiment, membranes according to the invention are used for the treatment of sea water,brackish water or surface water.

In one preferred embodiment of the invention, membranes according to the invention, particularly RO, FO or NF membranes are used for the desalination of sea water or brackish water.

Membranes according to the invention, particularly RO, FO or NF membranes are used for the desalination of water with a particularly high salt content of for example 3 to 8 % by weight. For example membranes according to the invention are suitable for the desalination of water from mining and oil/gas production and fracking processes, to obtain a higher yield in these applica- tions.

Different types of membrane according to the invention can also be used together in hybrid systems combining for example RO and FO membranes, RO and UF membranes, RO and NF membranes, RO and NF and UF membranes, NF and UF membranes.

In another preferred embodiment, membranes according to the invention, particularly NF, UF or MF membranes are used in a water treatment step prior to the desalination of sea water or brackish water. In another preferred embodiment membranes according to the invention, particularly NF, UF or MF membranes are used for the treatment of industrial or municipal waste water.

Membranes according to the invention, particularly RO and/or FO membranes can be used in food processing, for example for concentrating, desalting or dewatering food liquids (such as fruit juices), for the production of whey protein powders and for the concentration of milk, the UF permeate from making of whey powder, which contains lactose, can be concentrated by RO, wine processing, providing water for car washing, making maple syrup, during electrochemical production of hydrogen to prevent formation of minerals on electrode surface, for supplying water to reef aquaria.

Membranes according to the invention, particularly UF membranes can be used in medical applications like in dialysis and other blood treatments, food processing, concentration for making cheese, processing of proteins, desalting and solvent-exchange of proteins,

fractionation of proteins, clarification of fruit juice, recovery of vaccines and antibiotics from fermentation broth, laboratory grade water purification, drinking water disinfection (including removal of viruses), removal of endocrines and pesticides combined with suspended activated carbon pretreatment.

Membranes according to the invention, particularly RO, FO, NF membranes can be used for rehabilitation of mines, homogeneous catalyst recovery, desalting reaction processes.

Membranes according to the invention, particularly NF membranes, can be used for separating divalent ions or heavy and/or radioactive metal ions, for example in mining applications, homogeneous catalyst recovery, desalting reaction processes.

Another aspect of the invention are polymer blends comprising 10 to 90 % by weight of at least one polyarylene ether A, preferably polysulfone, polyphenylenesulfone or polyethersulfone, and 10 to 90 % by weight of at least one phenoxy resin P, wherein said phenoxy resin comprises hydrophilic side chain comprising at least one ionic group or at least one polyalkyleneoxide.

Another aspect of the invention are novel phenoxy resins P comprising a phenoxy backbone and at least one hydrophilic side chain comprising at least one polyalkylene oxide as disclosed above.

Another aspect of the invention are processes for making phenoxy resins P comprising a phenoxy backbone and at least one hydrophilic side chain comprising at least one polyalkylene oxide, comprising the steps

i) providing a phenoxy resin comprising a phenoxy backbone

ϋ) alkoxylating said phenoxy resin provided in step i).

Phenoxy resins and polymer blends according to the invention have high glass transition temperatures, high mechanical stabilities and at the same time a high hydrophilicity.

They are suitable for making membranes and for injection molding.

Examples

Abbreviations:

DCDPS 4,4'-Dichlorodiphenylsulfone

DHDPS 4,4'-Dihydroxydiphenylsulfone

NMP N-methylpyrrolidone

DMAc Dimethylacetamide

Phenoxy PKHH phenoxy resin obtained from Bisphenol A and epichlorohydrin, Mw = 63350 g/mol, Mn =14530 g/mol

PWP pure water permeation

Tg glass transition temperature MWCO molecular weight cutoff

DMF dimethylformamide

Ultrason^® E 6020P polyethersulfone with a viscosity number (ISO 307, 1 157, 1628; in 0.01 g/mol phenol/1 ,2 orthodichlorobenzene 1 :1 solution) of 82; a glass transition temperature (DSC, 10°C/min; according to ISO 1 1357-11-2) of 225 °C; a molecular weight Mw (GPC in DMAc, PMMA standard): 75000 g/mol

Luvitec^® K40 polyvinylpyrrolidone with a Polyvinylpyrrolidone with a solution viscosity characterised by the K-value of 40, determined according to the method of Fikentscher (Fikentscher, Cellulosechemie 13, 1932 (58))

The viscosity of polymers was measured as a 1 % by weight solution of the copolymer in NMP at 25 °C according to DI N EN ISO 1628-1 .

The molecular weight distribution and the average molecular weight of polymers were determined by GPC measurements in DMAc.

GPC-measurements were done using Dimethylacetamide/0.5 wt.-% LiBr as eluent. The concentration of the polymer solution was 4 mg/ml. After filtration (pore size 0.2 μηη), 100 μΙ of this solution was injected in the GPC system. For the separation 4 different columns (heated to 80°C) were used (GRAM pre-column, GRAM 30A, GRAM 1000A, GRAM 1000A, separation material: polyester copolymers). The system was operated with a flow rate of 1 ml/min. As detection system a DRI Agilent 1 100 was used.

The calibration was done with PMMA-standards with molecular weights (Mn) from 800 to 1820000 g/mol.

The compositions of polymers were determined using ¹ H-NMR in CDC . The signal intensity of resonance signals for H-atoms of polyalkylene groups was compared to the signal intensity of resonance signals for H-atoms of aromatic groups comprised in the phenoxy backbone. This comparison yields the ratio of polyalkylene oxide to the phenoxy backbone that can be can be used to calculate the content of polyalkylene oxide in the copolymer by weight.

The glass transition temperature of the products was determined by DSC analysis. All DSC- measurements were done using a DSC 2000 of TA Instruments at a heating rate of 20 k/min. About 5 mg material were placed in an Aluminum vessel and sealed. In the first run, the samples were heated to 250°C, rapidly cooled to -100°C and then in the second run heated to 250°C. The Tg-values given were determined in the second run.

The contact angles between the water and the surface of the films prepared by melt pressing the polymer samples were obtained using a contact angle measuring instrument (Drop shape analysis system DSA 10 MK 2 from Kruss GmbH Germany). For the contact angle measurement a sample of 2 cm² was fixed on an object plate. A water drop was put on the samples with a microliter gun. The shape of the droplet was recorded by a CCD-camera. An image recognition software analyzed the contact angle. For determining the flexibility and the hydrophilicity of the copolymers obtained, a 20 % by weight solution of the respective copolymer in DMF was applied onto a glass surface using a casting knife to obtain a coating with a thickness of 300 μηη. The solvent was left to evaporate and the polymeric films obtained were left to stand for 12 hours at room temperature and 12 hours at 80°C and 100 mbar. The polymeric films were removed from the glass surface and extracted for 16 hours using water with a temperature of 85 °C. The content of organic solvent in the polymeric films so obtained was then below 0.1 % by weight (determined by ¹H-NMR). The polymeric films were then dried for eight hours at 80°C and a pressure of 100 mbar.

Five tensile test samples were cut from the films using a die-cutter to obtain test specimen of the type 5A (ISO 527-2). The tensile strength of the films was determined at an elongation rate of 5 mm/min to determine the elongation at break. The numbers given below are the average values of 5 tests per polymer film.

To determine the hydrophilicity, samples prepared as described above were stored in deminer- alized water for five days. The samples were then wiped dry and the weight of the stored samples was determined. The water uptake was calculated relative to the weight of the sample prior to the storage in water.

The pure water permeation (PWP) of the membranes was determined using a pressure cell with a diameter of 60 mm using ultrapure water (salt-free water, additionally filtered by a Millipore UF-system) at a transmembrane pressure of 1 bar.

Die Ergebnisse der Prufungen sind in Tabelle 1 aufgefuhrt.

Example 1 : Copolymer 1

To 1000 ml of a 20 % by weight solution of Phenoxy PKHH in NMP, 1 .3 g of potassium tert- butylate were added. The solution obtained was heated to 120°C under a nitrogen pressure of 1 .5 bar. 60 g of ethylene oxide were added to the mixture in 15 minutes. The mixture obtained was maintained at 120°C for 10 hours. The mixture was let to cool to 100°C and stripped with nitrogen for 10 hours. The mixture obtained was then released from the reaction vessel at 80°C. For carrying out the analytics, a small portion of the reaction product was precipitated and washed with ethanol and dried

Tg= 24°C

Composition of the polymer obtained: 26 % by weight PEO-units; 74 % by weight phenoxy backbone. Example 2: Copolymer 2

To 1000 ml of a 20 % by weight solution of Phenoxy PKHH in NMP, 1 .3 g of potassium tert- butylate were added. The solution obtained was heated to 120°C under a nitrogen pressure of 1 .5 bar. 120 g of ethylene oxide were added to the mixture in 15 minutes. The mixture obtained was maintained at 120°C for 10 hours. The mixture was let to cool to 100°C and stripped with nitrogen for 10 hours. The mixture obtained was then released from the reaction vessel at 80°C. For carrying out the analytics, a small portion of the reaction product was precipitated and washed with ethanol and dried Tg= 2°C

Composition of the polymer obtained: 36 % by weight PEO-units; 64 % by weight phenoxy backbone.

Preparation of membranes

Example M1 : Preparation of PESU flat sheet membranes (reference membrane 1 )

Into a three neck flask equipped with a magnetic stirrer there were added 80 ml of N- methylpyrrolidone (NMP), 5 g of polyvinylpyrrolidone (PVP, Luvitec® K40) and 15 g of polyethersulfone (PESU, Ultrason® E 6020P). The mixture was heated under gentle stirring at 60°C until a homogeneous clear viscous solution was obtained. The solution was degassed overnight at room temperature. After that the membrane solution 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 operating at a speed of 5 mm/min. The membrane film was allowed to rest for 30 seconds before immersion in a water bath at 25°C for 10 minutes.

After the membrane had detached from the glass plate, the membrane was carefully transferred into a water bath for 12 h. Afterwards the membrane was transferred into a bath containing 2000 ppm NaOCI at 50°C for 4.5 h to remove PVP. After that process the membrane was washed with water at 60°C and the one time with a 0.5 wt.-% solution of NaBisulfite to remove active chlorine. After several washing steps with water the membrane was stored wet until characterization started.

A flat sheet continuous film with micro structural characteristics of UF membranes having dimension of at least 10x15 cm size is obtained. The membrane presents a top thin skin layer (1 -3 microns) and a porous layer underneath (thickness: 100-150 microns).

Example M2: Flat sheet membranes based on Copolymer 1

Into a three neck flask equipped with a magnetic stirrer were added 80 ml of N- methylpyrrolidone (NMP), 5 g of polyvinylpyrrolidone (PVP, Luvitec® K40) and 13 g of polyethersulfone (PESU, Ultrason® E 6020P) and 2 g of Copolymer 1. The mixture was heated under gentle stirring at 60°C until a homogeneous clear viscous solution was obtained. The solution was degassed overnight at room temperature. After that the membrane solution 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 operating at a speed of 5 mm/min. The membrane film was allowed to rest for 30 seconds before immersion in a water bath at 25°C for 10 minutes.

A flat sheet continuous film with micro structural characteristics of UF membranes having dimension of at least 10x15 cm size was obtained. The membrane presented a top thin skin layer (1 -3 microns) and a porous layer underneath (thickness: 100-150 microns).

Example M3: Flat sheet membranes based on Copolymer 1 Into a three neck flask equipped with a magnetic stirrer there were added 80 ml of N- methylpyrrolidone (NMP), 5 g of polyvinylpyrrolidone (PVP, Luvitec® K40) and 1 1 g of polyethersulfone (PESU, Ultrason® E 6020P) and 4 g of Copolymer 1. The mixture was heated under gentle stirring at 60°C until a homogeneous clear viscous solution is obtained. The solution was degassed overnight at room temperature. After that the membrane solution 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 operating at a speed of 5 mm/min. The membrane film was allowed to rest for 30 seconds before immersion in a water bath at 25°C for 10 minutes.

A flat sheet continuous film with micro structural characteristics of UF membranes having dimension of at least 10x15 cm size was obtained. The membrane presented a top thin skin layer (1 -3 microns) and a porous layer underneath (thickness: 100-150 microns). Example M4: Flat sheet membranes based on Copolymer 2

Into a three neck flask equipped with a magnetic stirrer there were added 80 ml of N- methylpyrrolidone (NMP), 5 g of polyvinylpyrrolidone (PVP, Luvitec® K40) and 13 g of polyethersulfone (PESU, Ultrason® E 6020P) and 2 g of Copolymer 2. The mixture was heated under gentle stirring at 60°C until a homogeneous clear viscous solution was obtained. The solution was degassed overnight at room temperature. After that the membrane solution 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 operating at a speed of 5 mm/min. The membrane film was allowed to rest for 30 seconds before immersion in a water bath at 25°C for 10 minutes.

Example M5: Flat sheet membranes based on Copolymer 2

Into a three neck flask equipped with a magnetic stirrer there were added 80 ml of N- methylpyrrolidone (NMP), 5 g of polyvinylpyrrolidone (PVP, Luvitec® K40) and 1 1 g of polyethersulfone (PESU, Ultrason® E 6020P) and 4 g of Copolymer 2. The mixture was heated under gentle stirring at 60°C until a homogeneous clear viscous solution was obtained. The solution was degassed overnight at room temperature. After that the membrane solution 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 operating at a speed of 5 mm/min. The membrane film was allowed to rest for 30 seconds before immersion in a water bath at 25°C for 10 minutes.

A flat sheet continuous film with micro structural characteristics of UF membranes having dimension of at least 10x15 cm size was obtained. The membrane presented a top thin skin layer (1 -3 microns) and a porous layer underneath (thickness: 100-150 microns). Membrane Characterization:

Using a pressure cell with a diameter of 60 mm, the pure water permeation of the membranes was tested using ultrapure water (salt-free water, filtered by a Millipore UF-system). In a subsequent test, a solution of different PEG-Standards was filtered at a pressure of 0.15 bar. By GPC-measurement of the feed and the permeate, the molecular weight cut-off was determined.

The fouling performance was tested by treating the membrane sample with a solution containing 1 wt.-% of Polyvinylpyrrolidon with a molecular weight (Mw) of 150.000 g/mol for 1 h. After that time the membrane was washed three times with 100 ml VE-water. After that, the flux measurement was run a second time. The ratio between the PWP after PVP-treatment and before PVP treatment is given as fouling ratio (FR). The data obtained is summarized in table 1.

Table 1 : Properties of membranes obtained in examples M1 to M5:

Sample M1 M2 M3 M4 M5

PWP [l/m2^*h^*bar] 450 640 830 740 850

MWCO 85 80 85 90 90

[kg/mol]

FR [%] 50 72 65 69 68

The membranes based on the new additives show higher water permeability at a comparable separation performance than the reference membrane and are also less prone to fouling caused by PVP.

Claims

1 . Membrane comprising at least one polymer A and at least one phenoxy resin P, wherein said phenoxy resin P comprises a phenoxy backbone and at least one hydrophilic side chain, wherein said hydrophilic side chain has a solubility in water of greater than 5 g/l at 23°C.

2. Membrane according to claiml , wherein said polymer A is a polyarylene ether.

3. Membrane according to claiml or 2, wherein said hydrophilic side chain comprises at least one ionic group and/or polyalkyleneoxide group.

4. Membrane according to claiml to 3, wherein said phenoxy backbone is obtainable by reacting a bisphenol and epichlorohydrin.

5. Membrane according to claim 4, wherein said bisphenol is selected from bisphenol A, bisphenol S and bisphenol F.

6. Membrane according to claims 1 to 5, wherein said polyalkylene oxide is polyethylene oxide.

7. Membrane according to claims 1 to 6, wherein said phenoxy resin P has a structure according to formula (II):

wherein

o + p = 10 to 200,

o : (o + p) = 0.05 to 1 ,

m = 2 to 200,

E is an end group.

Membrane according to claim 1 to 7, wherein said phenoxy resin P has an average molecular mass Mw of 5000 to 100000.

9. Membrane according to claims 1 to 8, wherein said phenoxy resin P comprises 20 to 85 % by weight of polyalkylene oxide groups based on the mass of the phenoxy resin P.

10. Membrane according to claims 1 to 9, wherein said polyarylene ether is a polysulfone, polyethersulfone or polyphenylenesulfone.

1 1 . Membrane according to claims 1 to 10, wherein said membrane comprises said phenoxy resin P in an amount of 0.01 % by weight to 20 % by weight.

12. Membrane according claims 1 to 1 1 , wherein said membrane is a UF, MF, RO, FO or NF membrane.

13. Use of membrane according to claims 1 to 12 for water treatment applications, treatment of industrial or municipal waste water, desalination of sea or brackish water, dialysis, plasmolysis, food processing.

14. Membrane element comprising membranes according to claims 1 to 12.

15. Membrane module comprising membranes according to claims 1 to 12.

16. Filtration system comprising membrane modules according to claim 15 or membrane elements according to claim 14.

17. Polymer blend comprising 10 to 90 % by weight of at least one polyarylene ether A and 10 to 90 % by weight of at least one phenoxy resin P comprising a phenoxy backbone and at least one hydrophilic side chain comprising at least one ionic group and/or polyalkyleneoxide group.

18. Phenoxy resin comprising a phenoxy backbone and at least one hydrophilic side chain comprising at least one polyalkyleneoxide group.