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WO1996006671A1 - Membrane presentant des proprietes osmotiques et procede de production - Google Patents

Membrane presentant des proprietes osmotiques et procede de production Download PDF

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Publication number
WO1996006671A1
WO1996006671A1 PCT/SE1995/000668 SE9500668W WO9606671A1 WO 1996006671 A1 WO1996006671 A1 WO 1996006671A1 SE 9500668 W SE9500668 W SE 9500668W WO 9606671 A1 WO9606671 A1 WO 9606671A1
Authority
WO
WIPO (PCT)
Prior art keywords
membrane
polyethylene glycol
microcrackled
surface layer
comprised
Prior art date
Application number
PCT/SE1995/000668
Other languages
English (en)
Inventor
Peter Henning Hagqvist
Osborn HÄRMESTAD
Original Assignee
Ab Electrolux
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
Application filed by Ab Electrolux filed Critical Ab Electrolux
Publication of WO1996006671A1 publication Critical patent/WO1996006671A1/fr

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
    • B01D71/06—Organic material
    • B01D71/40—Polymers of unsaturated acids or derivatives thereof, e.g. salts, amides, imides, nitriles, anhydrides, esters
    • B01D71/401—Polymers based on the polymerisation of acrylic acid, e.g. polyacrylate
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
    • B01D69/12—Composite membranes; Ultra-thin membranes
    • B01D69/125—In situ manufacturing by polymerisation, polycondensation, cross-linking or chemical reaction

Definitions

  • the present invention relates to a membrane having osmotic properties and also to the manufacture of such a membrane. More specifically, the invention relates to a membrane of this kind which is comprised of a specific type of base membrane on which a semipermeable layer having osmotic properties has been formed by polymerizing specific monomers. The invention also relates to the use of such a membrane in reverse osmosis water purifying processes.
  • the purification of water with the aid of reverse osmosis is a simple method which does not require the use of complicat ⁇ ed, space-consuming and expensive apparatus, as in the case of conventional water purification processes, and the reverse osmosis process has therefore been used widely in recent years.
  • the reverse osmosis method has already obtained wide use in individual dwellings that are located remote from conventional water purification plants, and the use of such methods and processes can be expected to find wide use in the developing countries in particular.
  • the pure water By applying a sufficiently high pressure to that side of the membrane on which the contaminated water is located, the pure water can be caused to be pressed through the membrane pores and out into the solution with a lower concentration of dissolved substances, while the dissolved substances remain on the contaminated side of the membrane and can be removed therefrom.
  • Reverse osmosis can also be referred to as a type of filtering process on a molecular scale.
  • the properties of the semipermeable membrane used are of a decisive importance to the practical purification of water with the aid of reverse osmosis. It is necessary for the membrane to exhibit a sufficient chemical resistance to the substances that may be present in the water (e.g. chlorine) , and also to have a sufficient mechanical strength to withstand the pressures applied, which are often relatively high and may reach about 10 MPa.
  • the requirements of high separation factors, high rates of flow and high mechanical strength are often contradictory.
  • the membrane In order to achieve a high rate of flow, the membrane must be as thin as possible, resulting in a greater risk that pin holes will form and therewith greatly reduce the separation factor, besides impairing the mechanical strength of the membrane.
  • a thin surface layer having semipermeable properties is of en mounted on a thicker plastic membrane having coarser pores, this membrane func- tioning as a carrier.
  • the composite membrane may possibly be mounted on a further carrier, such as a woven carrier or a wire net, in order to further enhance the mechanical strength.
  • EP-B1-0 015 149 describes the manufacture of a microporous membrane on which a semipermeable surface layer is applied. This patent specification also contains a large number of additional references to the state of the art.
  • the thin surface layer is formed on the surface of the membrane.
  • One method involves casting a layer of the polymer used for the surface layer on the surface of the membrane from a solution of the polymer.
  • Another method of forming the surface layer is to polymerize suitable monomers of the surface layer on the membrane so as to form a polymer layer, and then primarily a polyamide layer.
  • the primary achievement of this method is a polyamide which adheres to the membrane surface solely through addition forces, in other words a mechanical bond.
  • the method is performed in a liquid and it is necessary to subsequently leach out unreacted chemicals. This is unsuitable from an environmental aspect.
  • Another method of producing the surface layer involves supplying the monomers in a solvent together with a photo- initiator which is decomposed by UV-light and/or heat.
  • the polymerization reaction is initiated by exposing the mixture to UV-light or to heat, so that the initiator decomposes and forms free radicals which, in turn, initiate the polymeriza- tion process.
  • This method also requires non-reacted material to be subsequently washed out in a leaching bath.
  • the present invention removes the aforesaid drawbacks and provides a membrane having osmotic properties which fulfil the aforesaid requirements to a great degree.
  • a semipermeable membrane having osmotic properties which is characterized in that it is comprised of a microcrackled polymer film having applied thereon an outer layer comprised of a polymer of one or more polyethylene glycol monoacrylates and/or diacrylates of the general formula
  • n is a value such that the acrylates will obtain a mean molecular weight within the range of 100-1000
  • n will preferably have a value at which the mean molecular weight will lie within the range of 100-700.
  • Particularly preferred acrylates are those which have the aforesaid formulae, in which n has a value of 4-5 and/or 8-9. These acrylates then have the following formulae and data:
  • the preferred acrylates are not normally specific, pure compounds but mixtures of acrylates having varying values with regard to the number of ethylene glycol groups in the polyethylene glycol part.
  • the mean value will lie within the recited ranges of the n-value.
  • polyethylene glycol acrylate compounds used in accordance with the invention have not earlier been commercially available or described in the available literature. The compounds are therefore considered to be novel products.
  • the polyethylene glycol acrylate compounds according to the invention can be prepared in known manners.
  • a polyethylene glycol of desired molecular weight and degree of polymerization is reacted suitably with an acrylic acid halide, for instance the chloride, in the presence of an acid-binding substance, for instance a tertiary amine, such as triethylamine.
  • an acid-binding substance for instance a tertiary amine, such as triethylamine.
  • a monoacrylate is produced by reacting one equivalent of polyethylene glycol with one equivalent of the acrylic acid halide, while a diacrylate is produced by reacting one equivalent of the polyethylene glycol with two equivalents of the acrylic acid halide.
  • the reaction is suitably performed in a solvent that is able to dissolve the reactants and which is inert under the reaction conditions, for instance an ether, such as tetrahydrofuran.
  • a solvent that is able to dissolve the reactants and which is inert under the reaction conditions, for instance an ether, such as tetrahydrofuran.
  • the reaction mixture is then worked up in a conventional manner, by removing the formed amine salt and removing the solvent.
  • a microcrackled polymer film is used as a base membrane or support material .
  • Such a polymer film is characterized by containing a large number of microscopic, through-penetrating slits or cracks which impart the requisite porosity to the film.
  • the film will be covered entirely with a semipermeable surface layer withosmotic properties.
  • the resultant osmotic membrane is comprised of a porous carrier film which imparts the requisite mechanical strength to the membrane and which carries a surface layer polymerized thereon and having semipermeable properties.
  • the microcrackled base membrane preferably consists of a polyolefin, such as polyethylene or polypropylene or copoly- mers thereof.
  • a polyolefin such as polyethylene or polypropylene or copoly- mers thereof.
  • An appropriate example of such a base membrane is a microcrackled polyethylene film sold by PPG Industries in the U.S.A. under the trade name TES IN ® .
  • Such films have earlier found use in the clothing and printing fields, but have not been used for any purpose related to the ' present invention.
  • the polyethylene film will suitably have a thickness of 175 ⁇ m, although other thicknesses are conceiv- able, these thicknesses being readily determined by the person skilled in this art having knowledge of the require ⁇ ments placed on the use intended.
  • a semipermeable layer is produced on a membrane surface of a microcrackled polymer film by applying one or more of the inventive acrylate compounds to the surface together with one or more polymerization initiators.
  • the initiator/initiators is/are activated by applying UV-light, heat or some other energetic radiation form, and functions/function to initiate polymerization of the monomer or monomers.
  • it is important that at least one of the component acrylate compounds is a diacrylate.
  • Monoacrylates may be included as components in a polymerization mixture but cannot be used alone because no cross-linking will take place due to their monofunctionality.
  • the polymerization initiator may comprise any initiator known for use in polymerizing acrylic compounds.
  • One such initiator is comprised of a compound which decomposes under the influence of UV-light, heat or some other energetic radiation to form an activated radical which then initiates the monomer polymerization process.
  • Different types of initiators can be used in the polymerization process, such as radical, anionic, cationic and coordination initiators.
  • Such compounds may consist of benzophenone derivatives, organic peroxides or azo compounds, and a large number of such initiators are known to the person skilled in this art and are commercially avail ⁇ able.
  • the following list recites a number of polymerization initiators, by way of example only:
  • IRGACURE ® (benzophenone derivative, retailed by Ciba-Geigy AG; activated by UV-radiation) .
  • Benzophenone (activated by UV-radiation) .
  • Benzoyl peroxide (heat-activated) .
  • Azobisisobutyronitrile (heat-activated) .
  • the polymerization reaction itself consists of a typical radical polymerization of a well known kind.
  • the reaction can be performed in solvent or as a bulk polymerization process.
  • Alcohols such as methanol and ethanol, are examples of suitable solvents in this regard.
  • the monomer concentration of the solution may be between 1 and 15%, and is normally between 5 and 10% (w/v) .
  • a layer of a solution containing a monomer or monomers and a polymerization initiator is applied appropri ⁇ ately over the surface of the base membrane.
  • the layer can be applied to said surface in a number of different ways known to the skilled person, and graphic processes, such as offset printing, are also possible methods of application.
  • the layer of solution may be applied to a thickness of between 1 and 500 ⁇ m, and then preferably to a thickness of between 10 and 100 ⁇ m.
  • the layer of solution is then exposed to either UV-light or heat, depending on the type of polymer ⁇ ization initiator used.
  • the light When UV-light is used, the light will preferably have a wavelength between 170 and 450 nm, and the radiation dosage applied will preferably be between 50 and 200 mJ/cm 2 .
  • the layer may be irradiated for a period of between 5 and 60 seconds, and then typically between 10 and 20 seconds.
  • the properties strived for with the semipermeable layer on the base membrane are mechanical stability, chemical stabili ⁇ ty, a desired pore size and osmotic properties. These properties are controlled primarily by the degree of cross- linking achieved and by the chemical structure of the surface layer.
  • the degree of cross-linking is determined by the proportion of diacrylate in the polymeriza ⁇ tion mixture, such that greater proportions of diacrylate will result in higher degrees of cross-linking.
  • a certain amount of diacrylate must always be present, since it is only these difunctional monomers that can be cross-linked.
  • the diacrylates will normally comprise the major part of the polymerization mixture, while monoacry- lates are included to modify the properties of the polymer, for instance with regard to softness and pore size.
  • the chemical structure of the monomers primarily the length of the ethylene oxide segment between the acrylate groups, is also significant to the degree of cross-linking achieved and influences the chemical stability, pore size and the osmotic activity of the layer. Appropriate properties can be imparted to the semipermeable layer by a suitable choice of the polymerization components, if required after simple routine tests, as the person skilled in this art will know.
  • the triethylamine immediately begins to bind the hydrogenchloride formed, and the amine salt precipi ⁇ tates out and causes the solution to become turbid. The salt settles readily.
  • the mixture was left to stand for 12 hours for further reaction, while stirring the mixture. The reaction process was then stopped by adding 1 ml ethanol, which esterifies non-reacted acid chloride.
  • the reaction mixture was worked-up by filtering off the amine salt, and all of the tetrahydrofuran and ethanol was removed in a rotatory evaporator. To the residue, acetone was added two times, in an amount of 5-10 ml in each portion, to remove amine salt residues. The product is soluble in acetone, but not the amine salt. The mixture was chilled in a freezer and then filtered. If so desired, the acetone can then be evaporated so as to obtain the product in a pure form. The pure product is a slightly yellowish liquid product.
  • the method was carried out in the same way as that described above, with the exception that the starting material used comprised 20 g polyethylene glycol PEG 400 (0.05 mole) , 10.1 g triethylamine (0.1 mole) and 9.5 g acrylic acid chloride (0.1 mole) .
  • the starting material used comprised 20 g polyethylene glycol PEG 400 (0.05 mole) , 10.1 g triethylamine (0.1 mole) and 9.5 g acrylic acid chloride (0.1 mole) .
  • the mixture was left to finally react for three hours, whereafter the reaction was stopped and the mixture worked up in the aforesaid manner.
  • the pure product is a slightly yellowish liquid product.
  • Example 3 Manufacture of an osmotic membrane
  • a microcrackled polyethylene film having a thickness of 175 ⁇ m and comprising the material TESLIN ® (from PPG Industries, U.S.A.) was coated by means of an offset printing method with a 7 ⁇ m thick layer of polyethylene glycol diacrylate 400, containing 5 percent by weight of the UV-sensitive initiator IRGACURE ® 500 (from Ciba-Geigy AG, Basel, Switzerland) .
  • the surface was heated with warm air, to reduce the viscosity of the mixture so as to obtain a homogenous monomer film.
  • the surface was then irradiatedvith UV-light having a wavelength of between 170 and 450 nm at a dosage of 150 mJ/cm 2 . When the surface had cured, any remaining, non-reacted residual monomers were leached out with water.
  • a microcrackled polyethylene film having a thickness of 175 ⁇ m and comprised of the material TESLIN ® (from PPG Industries, U.S.A.) was coated by means of an offset printing method with a 50 ⁇ m thick layer of a solution containing 10 percent by weight polyethylene glycol diacrylate 400, and 1 percent by weight IRGACURE ® 500 (from Ciba-Geigy AG, Basel, Switzerland) in ethanol. The surface was heated with warm air to drive off the ethanol and to form a homogenous polymer film. The surface was then irradiated with UV-light having a wavelength of between 170 and 450 nm at a dosage of 200 mJ/cm 2 . When the surface had cured, any remaining non-reacted monomers were leached out with water.
  • TESLIN ® from PPG Industries, U.S.A.
  • the inventive membrane having osmotic properties can be used in a purely conventional manner in typical water purification apparatus by means of reverse osmosis. Such apparatus, their construction and their modus operandi are well known to the person skilled in this art-. It will be observed, however, that although the purification of water by means of reverse osmosis is a preferred area of use of the inventive membrane, the inventive membrane is not limited solely to this use.
  • the inventive membrane can be used within any area in which a semipermeable membrane is required in osmotic processes, and those modifications to the properties of the membrane which are required for a specific application can be readily determined by the person skilled in this art who has knowledge of the invention, and on the basis of simple routine experiments if so required.
  • the present invention enables the provision of a special combination of a microcrackled plastic base film and a semipermeable layer of novel, specific acrylate polymers polymerized thereon. In this way, there is obtained an osmotic membrane which exhibits a successful combination of properties .concerning separation ability and mechanical and chemical stability.

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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Macromonomer-Based Addition Polymer (AREA)

Abstract

La présente invention concerne une membrane semi-perméable présentant des propriétés osmotiques. Elle est réalisée à partir d'une membrane de base constituée d'une couche polymère microfissurée sur laquelle est appliquée une couche superficielle semi-perméable. Cette couche superficielle est constituée d'un polymère obtenu à partir d'un ou plusieurs monoacrylates-glycols de polyéthylène et/ou diacrylates-glycols de polyéthylène représentés par la formule générale CH2 = CH - CO - O - [ -CH2 - CH2- O - ]n - R dans laquelle R est hydrogène ou -CO - CH = CH2 et dans laquelle n présente une valeur telle que les acrylates pourront atteindre un poids moléculaire moyen allant de 100 à 1000. Selon la présente invention, le polymère de la couche superficielle doit contenir au moins un diacrylate-glycol de polyéthylène dans lequel R représente -CO - CH = CH2. Cette membrane convient particulièrement au procédé de purification d'eau par osmose inverse.
PCT/SE1995/000668 1994-08-31 1995-06-07 Membrane presentant des proprietes osmotiques et procede de production WO1996006671A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
SE9402892A SE502963C2 (sv) 1994-08-31 1994-08-31 Membran med osmotiska egenskaper, sätt för framställning samt användning till vattenrening
SE9402892-5 1994-08-31

Publications (1)

Publication Number Publication Date
WO1996006671A1 true WO1996006671A1 (fr) 1996-03-07

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WO (1) WO1996006671A1 (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004094049A1 (fr) * 2003-04-01 2004-11-04 Cuno, Inc. Membrane hydrophile et procede de fabrication de ladite membrane
WO2007018422A1 (fr) 2005-08-05 2007-02-15 Fujifilm Manufacturing Europe B.V. Membrane poreuse et support d'enregistrement comprenant celle-ci
EP1796198A3 (fr) * 2005-11-29 2007-08-15 Samsung SDI Co., Ltd. Membrane électrolyte polymère pour des piles à combustible et système de piles à combustible incluant celle-ci
US20110124025A1 (en) * 2009-11-20 2011-05-26 College Of Nanoscale Science And Engineering Cell Collecting Devices and Methods for Collecting Cells

Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0321241A2 (fr) * 1987-12-16 1989-06-21 Hoechst Celanese Corporation Membranes en résines durcissables par rayonnement ultraviolet
WO1990009230A1 (fr) * 1989-02-08 1990-08-23 Isis Innovation Limited Membranes composites et methode de fabrication de celles-ci
EP0410357A2 (fr) * 1989-07-27 1991-01-30 Millipore Corporation Membrane à surface hydrophile
US5071880A (en) * 1989-01-13 1991-12-10 Japan Atomic Energy Research Institute Process for producing a bifunctional filter membrane having iminodiacetic acid groups
US5209849A (en) * 1992-04-24 1993-05-11 Gelman Sciences Inc. Hydrophilic microporous polyolefin membrane

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0321241A2 (fr) * 1987-12-16 1989-06-21 Hoechst Celanese Corporation Membranes en résines durcissables par rayonnement ultraviolet
US5071880A (en) * 1989-01-13 1991-12-10 Japan Atomic Energy Research Institute Process for producing a bifunctional filter membrane having iminodiacetic acid groups
WO1990009230A1 (fr) * 1989-02-08 1990-08-23 Isis Innovation Limited Membranes composites et methode de fabrication de celles-ci
EP0410357A2 (fr) * 1989-07-27 1991-01-30 Millipore Corporation Membrane à surface hydrophile
US5209849A (en) * 1992-04-24 1993-05-11 Gelman Sciences Inc. Hydrophilic microporous polyolefin membrane

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004094049A1 (fr) * 2003-04-01 2004-11-04 Cuno, Inc. Membrane hydrophile et procede de fabrication de ladite membrane
US7067058B2 (en) 2003-04-01 2006-06-27 3M Innovative Properties Company Hydrophilic membrane and process for making the same
WO2007018422A1 (fr) 2005-08-05 2007-02-15 Fujifilm Manufacturing Europe B.V. Membrane poreuse et support d'enregistrement comprenant celle-ci
EP1796198A3 (fr) * 2005-11-29 2007-08-15 Samsung SDI Co., Ltd. Membrane électrolyte polymère pour des piles à combustible et système de piles à combustible incluant celle-ci
US8652706B2 (en) 2005-11-29 2014-02-18 Samsung Sdi Co., Ltd. Polymer electrolyte membrane for fuel cell and fuel cell system including the same
US20110124025A1 (en) * 2009-11-20 2011-05-26 College Of Nanoscale Science And Engineering Cell Collecting Devices and Methods for Collecting Cells

Also Published As

Publication number Publication date
SE9402892D0 (sv) 1994-08-31
SE502963C2 (sv) 1996-03-04
SE9402892L (sv) 1996-03-01

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