WO2002032557A1 - Method for producing a surface modified membrane - Google Patents

Method for producing a surface modified membrane

Info

Publication number
WO2002032557A1
WO2002032557A1 PCT/EP2001/011359 EP0111359W WO0232557A1 WO 2002032557 A1 WO2002032557 A1 WO 2002032557A1 EP 0111359 W EP0111359 W EP 0111359W WO 0232557 A1 WO0232557 A1 WO 0232557A1
Authority
WO
Grant status
Application
Patent type
Prior art keywords
agent
membrane
characterized
method according
surface
Prior art date
Application number
PCT/EP2001/011359
Other languages
German (de)
French (fr)
Inventor
Thorsten Niklas
Armin Lang
Original Assignee
Membrana Gmbh
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date

Links

Classifications

    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/66Polymers having sulfur in the main chain, with or without nitrogen, oxygen or carbon only
    • B01D71/68Polysulfones; Polyethersulfones
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D67/00Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002Organic membrane formation
    • B01D67/0009Organic membrane formation by phase separation, sol-gel transition, evaporation or solvent quenching
    • B01D67/0011Casting solutions therefor
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D67/00Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
    • B01D67/0002Organic membrane formation
    • B01D67/0009Organic membrane formation by phase separation, sol-gel transition, evaporation or solvent quenching
    • B01D67/0016Coagulation
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/02Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/08Hollow fibre membranes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D69/00Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12Composite membranes; Ultra-thin membranes
    • B01D69/125In-situ manufacturing by polymerisation, polycondensation, cross-linking, and/or reaction
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D71/00Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06Organic material
    • B01D71/54Polyureas; Polyurethanes
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2323/00Details relating to membrane preparation
    • B01D2323/12Specific ratios of components used
    • BPERFORMING OPERATIONS; TRANSPORTING
    • B01PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01DSEPARATION
    • B01D2325/00Details relating to properties of membranes
    • B01D2325/02Details relating to pores or pososity of the membranes
    • B01D2325/022Asymmetric membranes

Abstract

The invention relates to a method for producing a surface modified membrane, comprising the following steps a) production of a solution containing a synthetic polymer M in the form of a membrane, a solution system and an agent A comprising at least one functional group, b) shaping the solution into a moulded body comprising a first and second side, c) allowing a reaction on at least one of the sides of the moulded bodies of a coagulation medium which contains in a dissolved form an agent B reacting with agent A, and at least one functional group. A separation phase follows and a membrane structure is formed which comprises an inner porous surface and outer surfaces, whereby agent B, during said reaction, reacts with agent A on at least one of the outer surfaces and d) optionally, the solvent system is extracted and optionally dried. Said method allows a surface modified membrane to be obtained as a result of the reaction product of A and B.

Description

A process for producing a surface-modified membrane

Membrana GmbH, Wuppertal

Description:

The present invention relates to a method for preparing a surface-modified membrane.

For the surface modification of membranes are known a variety of methods which can be divided into chemical and physical modification process substantially.

To the group of chemical modification methods are those in which the surface of a previously fully formed membrane (the support membrane) count be altered chemically. Often, this will be at functional groups, or to the end groups of the membrane-forming polymer, which are partly on the surface, other polymers or monomers covalently attached. In another example of a chemical modification process, a reactive monomer is applied and brought into contact below with another monomer on a support membrane, wherein the two monomers react to form a formed from a polymeric network layer. Such a method is described in US 5 693 227. According to this document is a microporous Polysul- fonmembran for two minutes in a solution of 1, 3-phenylenediamine (PD) immersed and then removed from the PD-solution. Excess PD solution is removed. The resulting substrate is immersed for 20 seconds in a solution of trimesoyl chloride (TMC), forming a polymer network from PD and TMC. Thus, this method requires in addition to the necessary for the production of the support membrane process steps more further process steps and is therefore costly.

A member of the group of the physical process for the surface modification of membranes process is known as Bikomponentenspinnung. This involves using a triple comprising three mutually concentrically arranged outlet openings in the case of capillary or tube membranes, extruded simultaneously with the spinning solution and the internal filling is a further polymer solution around the outside of the spinning solution, such that during the phase inversion, a thin film made up of the spinning solution sets forming membrane and thus on the diaphragm a layer. However, the Bikomponentenspinnung is a technologically complex procedure because of the required Dreifachspinndüse.

Therefore, the present invention has as its object to provide a simpler process for the surface modification of membranes available.

This object is achieved by a method for producing a surface-modified membrane comprising the steps of a) preparing a solution comprising a membrane-forming synthetic polymer M, a solvent system, as well as an agent A containing at least one functional group, b) forming the solution into a shaped body with a first and second side, c) exposing at least one of the sides of the shaped body of a coagulating medium which contains dissolved B having at least one functional group reactive with the agent a agent, whereby a phase separation occurs and a membrane structure is formed, an inner pore surface, and having outer surfaces and wherein agent B during the exposing, at least on one of the outer upper lächen with agent a reacts and d) optionally, extracting the solvent system and, optionally,

Drying to obtain a surface-modified by the reaction product of A and B membrane is formed.

The inventive method requires only the already necessary for the preparation of unmodifi- ed membrane method steps. One only need in the preparation of the solution according to step a) and agent A in the preparation of Koa gulationsmediums used in step c), enforce agent B.

The membrane production itself are the known underlying processes in which the formation of the membrane structure through a non-solvent induced phase separation occurs. The usual while embodiments are also used in the method for the application.

Thus, by the inventive method in a preferred embodiment, hollow fiber membranes are prepared by mixing the polymer solution is extruded through the annular gap of a suitable hollow fiber spinneret with introduction of a lumen filling in the core bore of the nozzle. The extruded hollow fiber is then contacted with a coagulation medium which does not dissolve the polymer. Here, the membrane structure is formed. In this case, the extruded hollow fiber can be brought into contact with only its outer side with a coagulation, for example by being guided through a precipitation bath, wherein then a precipitation from the outside inwards. In another embodiment, the internal filling is a coagulation medium, and there is a precipitation of the membrane structure from the inside to the outside. Of course it is also possible that the extruded hollow fiber is brought into contact with both its outside and with its inner side with a coagulation medium. The precipitated hollow thread is then drawn off from the precipitation bath, then extracted the precipitating medium from the hollow fiber, and optionally removed by drying the extractant, whereby the finished hollow fiber membrane is obtained which has a lumen-side outer surface, an outer surface on the outside and an inner pore surface.

In accordance with the process variants described above for the preparation of a hollow fiber membrane, the step c take place) of the process according to the invention so that the hollow fiber is passed as coagulation in a precipitation bath, which comprises the dissolved agent B, whereby at least at the outer surface of the outer side of the resulting hollow fiber membrane agent B reacting with A agent. If, in the inventive method for forming the lumen acting as a coagulation inner filling a containing the agent B dissolved, reacted at least at the outer surface of the lumen side, ie at the lumen-side surface of the resulting membrane, agent B with agent A. If in the inventive process is carried out coagulation both the inner filling and through a coagulation bath, agent B may be dissolved in two coagulation media and thus a response from agent a to agent B both at least on the outer surface of the outer side and at least at the lumen-side surface take place , It is also possible that dissolved another agent B in the interior filler is contained as in the precipitation bath, whereby a hollow fiber membrane is obtained which is surface modified on at least the outer surface of its outer side by a different reaction product of A and B as at least on its luminal outer surface. Thus, with the inventive process optionally drying according to step d) hollow fiber membranes are produced which are surface modified, at least on the outer surface of its outer side and / or lumen side by the reaction product of A and B after extraction of the solvent system and.

With the inventive method flat membranes can be prepared in a further preferred embodiment. Here, the polymer solution is for example molded with a casting box to a roller and then, guided on the roller that is partially immersed in a non-solvent coagulating the polymer, into a precipitation bath in the coagulation. In this case, the membrane structure is formed starting from on the side remote from the roll side. In another embodiment, the roll is first coated with a polymer non-solvent coagulation medium and then the polymer solution, for example, formed with a pouring box on the surface coated with the coagulation roller into a film, wherein, starting on the side facing the roll side of the film a membrane structure formed. The film is then performed on the roll, which in turn is partially immersed in a coagulation medium in the coagulation, in which the side facing away from the roller side using a coagulation to the membrane structure. The precipitated flat membrane is withdrawn from the coagulation bath, then optionally the precipitating medium from the hollow fiber ex-tracted and optionally by drying the extractant whereby the finished flat membrane is obtained, having an outer roll side surface, an outer fällbadseitige surface and an inner pore surface removed.

In accordance with the process variants described above for the preparation of a flat membrane, step c) of the process according to the invention be such that the film is formed on a roller, the roller partially dissolved, the agent B in a coagulating bath containing immersed and the film on the roll by this precipitation bath to be led. Here agent reacts B at least at the outer surface of the side facing away from the roller side of the resulting flat membrane structure with agent A. Plotting in the inventive process prior to molding of the film a dissolved the agent B containing coagulation on the roller to react at least to the outer surface the facing of the roll side of the resulting flat membrane agent with agent A. If in the process of this invention, coagulation is effected B both above the precipitation bath and over the front of the shaping of the film applied to the roller coagulating agent a may be dissolved in two coagulation media and thus B take place a reaction of agent a to agent both at least on the side facing away from the roller side as well as at least on the side facing the drum side of the resulting flat membrane. It is also possible that in the immersed in the precipitation bath, the roller, another agent B is achieved than in the coagulation medium, which is applied to the roller before molding of the film, thereby forming a flat membrane that is applied to its outer roller-side surface is surface-modified by another reaction product of a and B than on its outer surface fällbadseitigen. Thus, with the inventive method by optionally extracting the solvent system and optionally drying in step d), flat membranes are produced which are surface-modified on at least the outer roller-side surface and / or on its outer fällbadseitigen surface by the reaction product of A and B.

Depending on the precipitation conditions in step c) of erfindungemäßen method, a large number of different membrane structures can be formed.

Thus, an asymmetric membrane structure with a fine pore or pore-free surface can be formed by, for example, that in step a) of the process according to the invention, a solvent system is selected which leads to the forces acting in step c) coagulating to a rapid phase inversion. In this case agent can not penetrate or only to a small extent into the interior of the forming membrane structure, B and there is a response from agent B with agent A mainly on the outer surface instead. In this case, part of dense layers of the reaction product of agent A can be produced with agent B on the outer surface.

Further, in step c) of the process according to the invention formed by phase separation membrane on the outer surface may be microporous. Such a membrane structure is produced known, for example in that a solvent system is selected in step a) of the process according to the invention, which leads to the forces acting in step c) to a slow coagulation phase inversion. In this case agent may renoberfläche not only on the outer surface but also to the inner polyvinyl react, thereby forming a membrane having a very large surface is obtained with the modified agent A B during the exposing of the coagulating medium.

With regard to the method used in the inventive membrane-forming polymer can be made to the well-known, for the production of membranes suitable synthetic polymers. Preferably, the membrane-forming synthetic polymer used in step a) for the preparation of the solution, M is a polyether sulfone, polysulfone or polyaryl ether sulfone. The solution can be added as additives, with which, for example, the formation of pores or the hydrophilicity of the membrane are influenced also other polymers such as polyethylene oxide, polyhydroxy ethers, polyethylene glycol, polyvinylpyrrolidone, polyvinyl alcohol or polycaprolactone, or inorganic substances such as SiO 2. In a particularly preferred embodiment of the method according to the invention is used as the membrane-forming synthetic polymer M polyethersulfone.

A particularly preferred mixture of solvent system consists of caprolactam and butyrolactone. By the ratio of caprolactam to butyrolactone can influence the membrane structure. The more caprolactam is used in relation to butyrolactone, the more tends the formed membrane structure in the direction of an asymmetric membrane having fine pores, or pore-free outer surface. The more butyrolactone is used in relation to caprolactam, the more tends the formed membrane structure in the direction of a microporous membrane on the outer surface. Such methods are described for example in EP-A-0361085 or in EP-A-0357021, which is expressly related to the relevant disclosure herein.

That in accordance with step c) of the inventive agent B is reactive with agent A, means in the context of the present invention is that A and B are reactive under the conditions of phase inversion, wherein the reaction must take place during the exposing of the coagulating medium, ie, in a time that is, depending on the membrane preparation process is between about 0.1 second and about 1 minute.

In the inventive process agent A and agent B at least one functional group.

In a preferred embodiment of the method according to the invention exhibit agent A and agent B in each case two functional groups to react and in step c) to a linear polymer. In this case, surface-modified membranes with a high stability of the surface modification, can be produced with the use of the membrane in various application media, in particular when the reaction product of agent A and agent B is a high molecular weight product.

In a further preferred embodiment of the method according to the invention exhibit agent A and / or B in each case more than two functional groups and react in step c) to form a crosslinked polymer. The thus surface-modified membrane is used in almost every use media without causing separation phenomena of surface modification because the crosslinked polymer of A and B is soluble due to its network property in any application medium.

To carry out the process of the invention agents with high reactivity are required. In a preferred embodiment of the inventive method, a dicarboxylic acid or a diisocyanate is used as an agent A.

is used as an agent A tere- phthaloyl or hexamethylene diisocyanate is particularly preferred in the present process, because these agents have a particularly high reactivity. In a preferred embodiment of the inventive agent B contains at least one imino group and two amino groups, because these agents have a high reactivity.

Particular preference is in the novel process agent B diethylenetriamine or polyethyleneimine, because its amino and imino groups have a particularly high reactivity.

In a further preferred embodiment of the method according to the invention is agent A and agent B terephthaloyl polyethyleneimine. With this combination of the agents A and B, a surface-modified with a crosslinked polymer of terephthaloyl chloride and polyethyleneimine membrane can be produced, which has a plurality of the polyethyleneimine derived imino groups, can be used because of their high reactivity for a variety of adsorption purposes. If we choose, for example, production conditions, which lead to a micro-porous at the outer surface of membrane to a membrane which is modified not only at its outer surface but also on its pore surface through the crosslinked polymer is selected from terephthaloyl chloride and polyethyleneimine and for adsorption reactions is obtained a very large surface area provides. Such membranes can be produced for example with polyether as the membrane-forming synthetic polymer M and a solvent system of butyrolactone and caprolactam with an excess of butyrolactone.

In a further preferred embodiment of the invention, agent A and agent B hexamethylene diethylene triamine. Thus, a surface-modified with a crosslinked polymer of hexamethylene diisocyanate and diethylenetriamine membrane is producible. If we choose, for example, production conditions, the pore-free or on the outer surface of a few pores lead having membrane gives a membrane that is substantially modified only at its outer surface by the crosslinked polymer of hexamethylene diisocyanate and diethylenetriamine. Such a membrane may for example be made with polyethersulfone as a membrane-forming synthetic polymer M and a solvent system of equal parts of butyrolactone and caprolactam. The crosslinked polymer forms on the outer surface of the membrane, a layer, whose thickness can be tailored, for example, adjust the amount of hexamethylene diisocyanate by. Therefore, this embodiment of the inventive method is particularly suitable for the production of nano-filtration membranes. Of course, the aforementioned combination of hexamethylene diisocyanate and diethylenetriamine can also be applied in processes in which a microporous membrane on its surface is prepared.

in step a) a solution is preferably prepared in the inventive method, which comprises 0.1 to 10 wt .-% of agent A.

Further, in step c) contains the coagulation process of the invention, the agent B in a concentration of 0.1 to 10 wt .-%.

Below said minimum concentrations surface modification achieved is too little pronounced. Above the said maximum concentrations may result in an undesirable disturbance of the formation of the membrane structure.

The invention is further illustrated by the following example.

example

A 20 ° C hot casting solution of 18 wt .-% of polyethersulfone, 8 wt .-% polyvinylpyrrolidone, 37 wt .-% of caprolactam and 37 wt .-% butyrolactone is knife-coated onto a glass plate and immersed in warm immediately precipitating bath a 20 ° C, the rin of glycerol and caprolactam in a ratio of 1: 1 with an addition of 2 wt .-% diethylene triamine (DETA) consists. Further, three additional flat membranes are prepared wherein each casting solutions of the above composition were used and in each case based on the coating solution 1, 2 and 8 wt .-% hexamethylene diisocyanate (HMDI) was added. Otherwise, how to proceed in the preceding paragraph.

1 shows SEM images of flat membranes prepared with 0, 1, 2 and 8 wt .-% HMDI. are shown in the pictures line a) of the glass plate and in the pictures line b) of the Fällbadseite facing surfaces, as well as in the pictures line c), the total cross-sections and the images line d) which faces the Fällbadseite cross sections of flat membranes.

Figure 1 shows that without HMDI (0 wt .-% HMDI) flat membrane produced has an asymmetric pore structure wherein the pore size decreases in the direction of the side facing the precipitation bath side. Figure 1 further shows that the addition of HMDI a layer on the side facing the Fällbadseite membrane surface is created (line images c) and d) with 1, 2, and 8 wt .-% HMDI). The layer consists of a polymeric network which is formed by polymerization of HMDI with DETA to a polyurea. Figure 1 finally shows that (b images line), and thickness (line images c) and d)) may adjust the layer by selecting a certain amount of HMDI targeting the respective desired values ​​of surface porosity.

Claims

A process for producing a surface-modified MembranMembrana GmbH, Wuppertal Patent claims:
1. A method for preparing a surface-modified membrane comprising the steps of a) preparing a solution comprising a membrane-forming synthetic polymer M, a solvent system, as well as an agent A containing at least one functional group, b) forming the solution into a shaped body having a first and second side c) exposing at least one of the sides of the shaped body of a coagulating medium which contains a reactive with the agent a agent B dissolved with at least one functional group, thereby forming a phase separation occurs and a membrane structure is formed which has an inner pore surfaces and outer surfaces, and wherein agent B at least responding during the exposing of one of the outer surface with agent a and d) optionally, extracting the solvent system and optionally drying to obtain a surface-modified by the reaction product of a and B membrane is formed.
2. The method according to claim 1, characterized in that in step a) the membrane-forming synthetic polymer M is a polyether sulfone, polysulfone or polyaryl ether sulfone is.
3. The method of claim 1 or 2, characterized in that in step a) is the solvent system of caprolactam and butyrolactone.
4. The method according to one or more of claims 1 to 3, characterized in that agent A and agent B having two functional groups and react in step c) to a linear polymer.
5. The method according to one or more of claims 1 to 3, characterized in that agent A and / or agent B each have more than two functional groups and react in step c) to form a crosslinked polymer.
6. The method according to one or more of claims 1 to 5, characterized in that agent A is a dicarboxylic acid or a diisocyanate.
7. The method according to claim 6, characterized in that agent A is terephthaloyl chloride or hexamethylene diisocyanate.
8. The method according to one or more of claims 1 to 3 and 5 to 7, characterized in that the agent B contains at least one imino group and two amino groups.
9. The method according to claim 8, characterized in that agent B diethylenetriamine or polyethyleneimine.
10. The method according to one or more of claims 1 to 3 and 5 to 9, characterized in that agent A and agent B terephthaloyl chloride is polyethyleneimine.
11. The method according to one or more of claims 1 to 3 and 5 to 9, characterized in that agent A and agent B is hexamethylene diisocyanate diethylenetriamine.
12. The method according to one or more of claims 1 to 11, characterized in that in step a) a solution is prepared which contains 0.1 to 10 wt .-% of agent A.
13. The method according to one or more of claims 1 to 12, characterized in that in step), the coagulation contains dissolved in a concentration of 0.1 to 10 wt .-% c the agent B.
PCT/EP2001/011359 2000-10-17 2001-10-02 Method for producing a surface modified membrane WO2002032557A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE10051366.2 2000-10-17
DE10051366 2000-10-17

Publications (1)

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WO2002032557A1 true true WO2002032557A1 (en) 2002-04-25

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4337154A (en) * 1979-04-04 1982-06-29 Nippon Shokubai Kagaku Kogyo Co., Ltd. Crosslinked composite semipermeable membrane
US5232601A (en) * 1992-05-29 1993-08-03 W. R. Grace & Co.-Conn. High flux hollow fiber membrane

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4337154A (en) * 1979-04-04 1982-06-29 Nippon Shokubai Kagaku Kogyo Co., Ltd. Crosslinked composite semipermeable membrane
US5232601A (en) * 1992-05-29 1993-08-03 W. R. Grace & Co.-Conn. High flux hollow fiber membrane

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