Method for producing microporous polymer structures

Abstract

A method for producing a microporous polymer structure (1) having at least one porous region (2) and a substantially non-porous support structure (3) configured to support the at least one porous region (2), the method comprising: i) providing a substrate (4); ii) providing a first composition (5), the first composition (5) comprising a first polymer (5a), at least one solvent (5b) for the first polymer, and one or both of nanoparticles and microparticles (5c) dispersed within the first composition (5); iii) providing a second composition (6) comprising a second polymer (6a); and iv) applying the first composition (5) to a surface (4a) of the substrate (4) to form a first coating layer (7). v) carrying out phase separation in the first coating layer (7) to obtain a phase-separated coating layer (7'); vi) applying a second composition (6) onto the same surface (4a) of the substrate (4) and / or the phase-separated first coating layer (7'); vii) physically hardening or curing the second composition (6) applied in step vi) to obtain a non-porous support structure (3); and viii) dissolving the nanoparticles and / or microparticles (5c) with a washing solvent to obtain a porous region (2), wherein the non-porous support structure and the porous region are disposed on the substrate to form a common interface, and the phase separation in the first coating layer (7) in step v) is carried out from one side of the first coating layer (7).

Description

[Technical Field]

[0001] The present invention relates to a method for producing a microporous polymer structure, a microporous polymer structure and a filtration device according to the independent claims. [Background technology]

[0002] Filtration is a common method used to separate solids from fluids using porous filter membranes. Particles smaller than the membrane pores can still pass through this mechanical barrier, while larger particles accumulate on the feed side. Depending on the actual pore size, membranes are classified as microfiltration, with pore sizes up to 100 nm, and ultrafiltration, with pore sizes between 2 and 100 nm. Moving on to nanofiltration, i.e., pore sizes between 0.5 and 2 nm, and reverse osmosis, with pore sizes below 0.5 nm, separation occurs due to the mechanical barrier of polymer chains rather than the actual pores.

[0003] Microfiltration and ultrafiltration membranes are generally made by a phase inversion process, as described, for example, in U.S. Pat. No. 6,267,916. They involve casting a polymer dope solution onto a substrate and then quenching the dope solution. During this deposition process, pores are formed in the polymer layer. This process is also known as non-solvent induced phase separation (NIPS). Instead of using a non-solvent, separation can be induced by lowering the temperature of the cast polymer dope solution. This temperature induced phase separation (TIPS) process is further described, for example, in U.S. Pat. No. 5,444,097.

[0004] In addition to membrane manufacturing processes based on any type of phase separation, manufacturing processes using plain or coated template particles for pore formation have shown great potential and relevance for large-scale membrane manufacturing. For example, as described in EP 2 665 767, this process uses nanoparticles and / or microparticles as pore templates to form a polymer-template composite. In the next step, the template particles are dissolved to expose the porous membrane structure. Because high porosity is important for achieving high permeability, this template-based process offers simple control over the desired porosity with a minimal amount of template particles used.

[0005] However, the higher the porosity, the worse the mechanical properties of the porous membrane, regardless of the manufacturing method used. The deterioration of mechanical properties can be counteracted to some extent by incorporating a porous support, such as a woven or nonwoven fabric, to form a composite porous membrane, as described, for example, in EP 1 666 129, but this impairs permeability.

[0006] To improve the mechanical properties and make the membrane self-supporting, the thickness of the membrane can of course be increased, but this reduces the production rate due to the extra solvent involved. Furthermore, permeability is also compromised because flow resistance is proportional to the square of the pore size and pore length. Therefore, thick membranes with small pores are particularly prone to relatively low permeability.

[0007] Recently, processes for producing asymmetric membranes have been developed that offer a good compromise between mechanical stability and permeability. For example, U.S. Patent Nos. 6,736,971 and 8,123,992 describe configurations for producing bilayer membranes with different porosities. In this way, the selective layer with smaller pores can be made thinner without losing the stability of a relatively thick membrane. However, these membranes do not achieve the smooth transition or gradient of pore size between the bottom side and the top side or surface, which would be most beneficial.

[0008] In addition to the need for a highly permeable membrane, it is also generally required that the membrane be reliably sealed to the filter housing in which it is housed. Sealing can be achieved by gluing or welding the membrane edges together or into a sealing cap. While gluing is considered simpler, the possibility of subsequent leaching of adhesive additives can be problematic, particularly when the membrane is intended for use in drinking water applications or pharmaceutical environments. Therefore, thermal bonding, such as ultrasonic or infrared welding, is a preferred method for sealing the membrane edges without adding the risk of leachable components. Nevertheless, this method has certain drawbacks, particularly the fact that it subjects the membrane to thermal and mechanical stresses that can damage the porous regions and adversely affect membrane performance. Ideally, it would be desirable for the membrane to have a sealing area with no porosity and a filter area with high, asymmetric porosity. Summary of the Invention [Problem to be solved by the invention]

[0009] The object of the present invention is to overcome these and other drawbacks of the prior art, and in particular to provide an improved method for producing microporous polymer structures, in particular membranes, which is cost-effective, reliable, and easy to implement, and allows for control of the porosity within the microporous polymer structure. A further object is to provide a microporous polymer structure, in particular a membrane, which can be safely and easily attached to a partner, such as a filter housing, and which is characterized by a high asymmetric porosity while maintaining good mechanical stability. [Means for solving the problem]

[0010] This object is achieved according to the independent claims by a method for producing a microporous polymer structure having at least one porous region and a substantially non-porous support structure configured to support said at least one porous region, a microporous polymer structure, and a filtration device comprising at least one microporous polymer structure as disclosed herein. Advantageous embodiments are the subject of the dependent claims.

[0011] In the context of the present invention, the term "non-porous" means that each region is essentially free of interconnected pores.

[0012] As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0013] A method for making a microporous polymer structure having at least one porous region and a substantially non-porous support structure configured to support the at least one porous region comprises the steps of: In step a), a substrate is provided. The substrate may be a porous substrate or a non-porous substrate selected from the group consisting of fabrics, nonwovens, foams, synthetic polymers, biopolymers, ceramics, metals, glass, and combinations thereof. Additionally or alternatively, the substrate may have a two-dimensional or three-dimensional shape.

[0014] In step b), a first composition is provided, the first composition comprising a first polymer, at least one solvent for the first polymer, and one or both of nanoparticles and microparticles dispersed within the first composition.

[0015] For the method to function particularly reliably, the viscosity of the first composition when provided in step b) may be about 2000 to 30000 mPa·s, in particular measured in a viscometer equipped with a cone appropriate for the viscosity range at a shear rate of 100 1 / s and a temperature of 30° C. Additionally or alternatively, the concentration of the first polymer in the first composition is preferably 10% to 35% based on the total weight of the first composition.

[0016] The first polymer may be one or more polymers selected from the group consisting of polysulfone, polyethersulfone, polycarbonate, polystyrene, polyacrylate, polysiloxane, polyarylate, polyurethane, polyester, polyether, polyimide, polyamide, halogenated polyolefin, cellulose acetate, and liquid crystal polymer. Alternatively, the first polymer may be a polymer or copolymer as described above that is functionalized via post-polymerization, sulfonation, phosphorylation, amination, or quaternization. Additionally or alternatively, the first polymer may be selected from the group consisting of oligomers that can be polymerized or crosslinked. The use of oligomers can provide lower viscosity and facilitate coating of the substrate, particularly when the substrate features a complex shape or when complete coverage of the substrate is desired. Crosslinking can increase the durability of the coating and / or the durability of the free-standing microporous polymer structure after removal from the substrate, respectively.

[0017] For the method to work particularly reliably, the average molecular weight of the first polymer may be about 5,000 to 500,000 g / mol, particularly as determined by gel permeation chromatography (GPC). As will be appreciated by those skilled in the art, the internal standard and solvent for determining molecular weight by GPC may vary depending on the polymer.

[0018] As will be appreciated by those skilled in the art, suitable solvents for the first polymer can be selected based on the respective polymer or polymers to be dissolved. It is preferred if the solvent for the first polymer has a boiling point below 230°C. This temperature range allows for energy savings compared to solvents with higher boiling points and also reduces the risk of damage to the microporous polymer structure due to thermal or thermal-oxidative stress. Examples of suitable solvents for the first polymer include water or organic solvents selected from the group consisting of alcohols, ethers, ketones, esters, halogen-alkanes, alkanes, cycloalkanes, sulfoxides, amides, pyrrolidones, lactones, and lactams.

[0019] For the method to function particularly reliably, the particle to polymer ratio of the nanoparticles and / or microparticles contained in the first composition may be, in particular, about 49:51 to 90:10 (particles:polymer), based on the weight of the first polymer.

[0020] The first composition may contain one or more additives selected from a wide variety of additives and mixtures thereof known in the art. In particular, the additives may be selected from the group consisting of surfactants, polymerization initiators, stabilizers, crosslinkers, wetting agents, thickeners, curing agents, leveling agents, film flow agents, film uniformity agents, defoaming agents, anti-orange peel agents, and mixtures thereof. In a preferred embodiment, the first composition contains at least one hydrophilicity-enhancing additive, particularly those disclosed in WO 02 / 42530. The use of one or more hydrophilicity-enhancing additives is intended to reduce the adhesion of air bubbles or other hydrophobic materials in the pores, which would otherwise adversely affect flow.

[0021] In step c), a second composition is provided. The second composition comprises a second polymer or a precursor to a second polymer. Optionally, the second composition further comprises at least one solvent for the second polymer.

[0022] For the method to function particularly reliably, the viscosity of the second composition when provided in step c) may be about 500 to 10,000 mPa·s, in particular measured at a temperature of 30° C. in a viscometer equipped with a cone appropriate for that viscosity range. Additionally or alternatively, it is preferred that the concentration of the second polymer in the second composition is 10% to 35% based on the total weight of the second composition.

[0023] The first polymer and / or the second polymer may be selected from the group consisting of polysulfone, polyethersulfone, polycarbonate, polystyrene, polyacrylate, polysiloxane, polyarylate, polyurethane, polyester, polyether, polyimide, polyamide, halogenated polyolefin, cellulose acetate, liquid crystal polymer, and precursors thereof.

[0024] For the method to function particularly reliably, the average molecular weight of the second polymer, as determined by GPC, can be, in particular, about 5,000 to 500,000 g / mol. As with the first polymer, the internal standard and solvent for determining molecular weight by GPC can vary depending on the polymer, as will be understood by those skilled in the art.

[0025] Suitable solvents for the second polymer may be selected based on the respective polymer or polymers to be dissolved, as will be understood by one of ordinary skill in the art.

[0026] In step d), the first composition is applied to the surface of the substrate provided in step a) to form a first coating layer on the substrate.

[0027] For the method to work particularly reliably, it is preferred that the temperature of the first composition at or during application in step d) is between 20°C and 40°C.

[0028] In an optional step e), the first coating layer formed in step d) is subjected to an atmosphere that promotes evaporation of at least one solvent for the first polymer.

[0029] For the method to work particularly reliably, it is preferred that in step e) the first coating layer is heated to a temperature of between 60° C. and 80° C. Additionally or alternatively, it is preferred that the evaporation in step e) is carried out over a period of between 0.5 and 15 minutes.

[0030] In step f), phase separation is carried out in the first coating layer to obtain a phase-separated first coating layer. The phase separation in the first coating layer in step f) is carried out from one side of the first coating layer to create an asymmetric structure in the first coating layer, which will later become the porous region of the microporous polymer structure. Phase separation can be induced in the first coating layer by exposing the first coating layer to a non-solvent atmosphere (drying process) and / or by temperature change, as further described below. Preferably, the phase separation in the first coating layer in step f) is carried out from the substrate side, which allows particularly good control of this process step and minimizes the risk of damaging the unsupported surface facing away from the substrate.

[0031] In step g), a second composition is applied to the same surface of the substrate provided in step a), which is then coated with the first composition in step d). The application of the second composition is carried out in a patterned manner according to the desired or required shape of the support structure for supporting the porous region. Additionally or alternatively, the second composition is applied in a patterned manner onto the phase-separated first coating layer formed in step d). It is also contemplated that the application of the first composition in step d) and the application of the second composition in step g) may proceed substantially simultaneously, particularly as described in more detail below.

[0032] For the method to work particularly reliably, it is preferred that the temperature of the second composition at or during application in step g) is between 0.5 and 15 minutes.

[0033] In step h), the second composition applied in step g) is physically hardened (e.g., by evaporation of the solvent) or cured to provide a non-porous support structure. The non-porous support structure and the porous region are disposed on the substrate such that they form a common interface.

[0034] In step i), the nanoparticles and / or microparticles are dissolved in a washing solvent to obtain a porous region. To achieve faster dissolution, the nanoparticles and / or microparticles are preferably dissolved in an acidic aqueous solution.

[0035] The "washing solvent" described herein is a non-organic solvent (e.g., water) used to remove salt particles from their polymer matrix, i.e., the phase-separated first coating layer, by dissolving them in the non-organic solvent. The wash solvent is characterized by not dissolving the polymers contained in the first and second compositions used in the manufacturing processes described herein. Furthermore, while the wash solvent is preferably used in the methods described herein, it does not necessarily have to be in a liquid aggregate state. Step i) may also include multiple washes, with optional drying between washes. When using a multi-step protocol involving multiple washes, the same or different wash solvents may be used, e.g., first a dilute aqueous acid solution, followed by water.

[0036] In an optional step j), the microporous polymer structure obtained after step i) is dried. Drying can be carried out until a predetermined weight loss or weight constancy. For the method to function particularly reliably, it is preferred that the microporous polymer structure obtained after step i) is heated in step j) to a temperature between 60°C and 180°C. Additionally or alternatively, it is preferred that the drying in step j) is carried out for a period of between 0.5 and 15 minutes.

[0037] The microporous polymer structures disclosed herein may particularly be membranes, and the methods herein are particularly one of producing membranes.

[0038] The methods for producing microporous polymer structures disclosed herein are cost-effective, reliable, and easy to implement. The methods disclosed herein result in microporous polymer structures, particularly membranes, that are structurally distinct from membranes formed by lamination or extrusion processes of two or more polymer films in that the microporous polymer structures of the present invention are characterized by a truly asymmetric pore size distribution, further achieved by phase separation. Furthermore, the methods disclosed herein enable the realization of "open areas," i.e., porous regions, of virtually any size, which is not possible with conventional woven or nonwoven materials but is possible by using a "flowing" polymer, i.e., first composition. As will be apparent to those skilled in the art, interdiffusion of the first and second compositions can be taken into account when designing the manufacturing process, and yet larger, individually adjustable "open areas" can be achieved with the methods disclosed herein.

[0039] The asymmetric microporous polymer structures provided by the present invention typically comprise a relatively thin, dense separating layer, e.g., 10 nm to 50 nm, and a relatively thick porous layer, the latter providing mechanical stability and efficient transport of filtrate. Thus, the asymmetric porous polymer structures disclosed herein combine the high permeate flow provided by the separating or selective layer with the reasonable mechanical stability resulting from the relatively thick porous layer. Mechanical stability is significantly further enhanced by a substantially nonporous support structure, as disclosed herein. Furthermore, the microporous polymer structures disclosed herein exhibit a pore size gradient, further distinguishing them from membranes formed by laminating two or more polymer films.

[0040] The microporous polymer structures disclosed herein are self-supporting ("freestanding"). They are therefore distinct from known porous polymer structures of similar thickness and porosity on a support. However, the microporous polymer structures disclosed herein are equally suitable for coating any suitable support. The possibility of producing such microporous polymer structures independently of a specific support makes them highly versatile.

[0041] The microporous polymer structures disclosed herein are useful for applications in, for example, ultrafiltration (UF) and microfiltration (MF). Ultrafiltration is used to separate particles between 2 and 100 nm, such as viruses, proteins, and colloids. Microfiltration is used to separate particles between 100 and 1000 nm, such as bacteria.

[0042] The method disclosed herein may further comprise step k) of removing the microporous polymer structure from the substrate. In this embodiment, step k) is performed after any one of steps g) to j). In this way, a free-standing microporous polymer structure, particularly a free-standing membrane, is obtained.

[0043] In a preferred embodiment of the method disclosed herein, steps d) and g) are carried out simultaneously, followed by step f), which allows for a particularly fast and efficient manufacturing method.

[0044] In a preferred embodiment of the method disclosed herein, the application of the first composition in step d) and / or the application of the second composition in step g) is carried out by solvent casting, extrusion, or printing.The first and / or second compositions can be very well processed or applied by the above-mentioned means.Printing is particularly preferred because it allows the production of particularly fine or detailed structures, which is particularly advantageous when processing the second composition because the resulting support structure can be designed particularly effectively at the same time.

[0045] In a preferred embodiment of the method disclosed herein, the phase separation in step f) is carried out by applying heat above 40° C. to one side of the first coating layer, preferably from the substrate side. Heating from the substrate side, i.e., from the side facing through the substrate and away from the accessible surface of the first coating layer, reduces the risk of damage to this surface during heating, for example by convection, thereby making it possible to achieve a higher surface quality.

[0046] In a preferred embodiment of the method disclosed herein, the second composition comprises a precursor of the second polymer, the precursor being selected from one or more of a radiation-curable monomer and a radiation-curable oligomer. In this embodiment, curing of the second composition in step h) is carried out by radiation curing using ultraviolet (UV) light or high-energy electrons from an electron-beam (EB) source.

[0047] Compared to thermal curing, the use of UV light to cure the second composition has the advantage of significantly shortening curing times, typically in the range of a few seconds. This is advantageous for high-throughput or continuous processes, as it eliminates the need for long drying sections, which entails high space requirements and costs. Aside from improved turnaround time, UV curing of the second composition also allows the second composition to produce finer, more defined structures, since the flow or mixing of the second composition with the first composition is reduced by the rapid curing with UV light.

[0048] The UV light used to cure the second composition preferably has a wavelength between 280 and 400 nm. This wavelength range allows for deep curing, resulting in the formation of a tough coating with a significantly reduced number of unreacted reactive groups that would otherwise lead to leaching of the respective monomers or oligomers from the cured composition. This is particularly important in medical applications, where harmful or toxic compounds must not leak from the porous polymer material.

[0049] A wide variety of polymers can be used in the microporous polymer structures of the present invention, which is considered advantageous since the porous polymer structures known from the prior art are limited in consideration of suitable materials and / or the properties of their pores.

[0050] In a preferred embodiment of the method disclosed herein, the first polymer and the second polymer are the same, i.e., at least one first polymer contained in the first composition and at least one second polymer contained in the second composition are the same polymer. In this way, the complexity of the entire method can be reduced, and costs can be reduced. However, it is also conceivable that the first polymer and the second polymer are not the same, i.e., at least one first polymer contained in the first composition and at least one second polymer contained in the second composition are different polymers. In the latter case, they should be selected by those skilled in the art based on their solubility in the same solvent, their co-precipitation behavior, and / or their shrinkage behavior.

[0051] In preferred embodiments of the methods disclosed herein, the nanoparticles and / or microparticles are selected from the group consisting of oxides, carbonates, sulfates, halides, nitrates, and phosphates. Preferably, the nanoparticles and / or microparticles are selected from the group consisting of oxides and carbonates, most preferably calcium carbonate (CaCO), barium carbonate (BaCO), strontium carbonate (SrCO), sodium carbonate (NaCO), potassium carbonate (KCO), sodium chloride (NaCl), zinc oxide (ZnO), and calcium oxide (CaO). The above-mentioned salts and oxides are generally readily available, reasonably priced, and readily soluble, especially under acidic aqueous conditions.

[0052] Additionally or alternatively, the nanoparticles and / or microparticles have a particle size of 1 to 5000 nm, preferably 5 to 600 nm, which represents a favorable compromise between pore size, porosity, inter-pore connectivity, and particle leachability.

[0053] The size of nanoparticles and / or microparticles present in polymer dispersions is determined by using a laser diffraction spectrometer in combination with the polarization intensity differential scattering (PIDS) technique. To calculate the particle size distribution, the refractive index ratio was chosen according to the solvent used.

[0054] The pore size of particles with a particle size between 0.01 µm and 5 µm is determined by the fluorescent readout of fluorescently labeled polystyrene microspheres or silica microspheres according to the following measurement protocol, which shows test particles with a size of 0.5 µm as an example: (i) Preparation of challenge solution: Fluorescent particles available from ThermoFisher (FluoSpheres™, 0.5 μm, red fluorescence (580 / 605), F8812) or Micromod Partikeltechnologie GmbH (product code: 42-00-502 sicastar®-greenF) are diluted with 0.01% by volume polyoxyethylene (20) sorbitan monooleate (Tween® 80) in deionized water to give a final particle concentration of 1:1000.

[0055] (ii) Bead retention test The porous polymer structure specimens to be analyzed are placed in a filter housing (effective filter area 6–20 cm) containing a woven or nonwoven support structure (e.g., Novatexx 2413, Freudenberg) to support the specimen within the filter housing. 2 ) The support must be such that mechanical stress on the membrane is minimized and therefore the membrane does not stretch under pressure. A defined volume of challenge solution is poured into the resulting test cell. The challenge solution is passed through the test strip at an air pressure of 1 to 6 bar so that the membrane's inherent bubble point is overcome and the entire volume of the challenge solution passes through the test strip. The permeate is discarded and step (ii) is repeated. This time, the permeate is collected in a clean plastic weighing dish for analysis.

[0056] (iii) Analysis Pipette deionized water, challenge solution, and permeate solution (250 μL each) into a well plate (e.g., a 96-well plate). Perform fluorescence readout using a plate reader (e.g., Tecan) using the following protocol: Following 10 seconds of orbital shaking, Top readout of red fluorescent particles without lid; Ex. / Em. 540(25) / 620(20)nm; Gain calculated from well with "full" signal, 25 flashes, 20µs integration time, readout of a 3x3 square area, 1000µm boundary.

[0057] Top readout of green fluorescent particles without lid; Ex. / Em. 465(20) / 510(20)nm; Gain calculated from well with "full" signal, 25 flashes, 20µs integration time, readout of a 3x3 square area, 1000µm boundary.

[0058] The water reading represents the blank signal, the challenge solution reading represents the full signal, and the permeate reading represents the sample signal.

[0059] The retention rate, R, is then calculated from the wells as follows:

[0060]

number

[0061] If R is greater than 90%, the challenge particle is filtered out and the porous polymer structure is said to have a pore size smaller than the challenge particle size (in this example, it is 0.5 μm).

[0062] (iv) Dilution Adaptation If the blank fluorescence reading is 10% or more of the full fluorescence reading, the dilution shall be reduced until the blank is less than 10% of full.

[0063] The pore size of particles with a diameter between 1 nm and 100 nm was determined by a dextran rejection test performed to determine the molecular weight cutoff (MWCO). For details, see G. Tkacik and S. Michaels, Nature Biotechnology. 9:941-946, 1991. A membrane capable of rejecting at least 90% of 1000 kDa macromolecules can be classified as having a 1000 kDa MWCO. A 0.1 wt% mixture of different dextran standards (5 kDa, 25 kDa, 80 kDa, 150 kDa, 270 kDa, 410 kDa, 670 kDa, and 1400 kDa) (Fluka, CH) was prepared in 0.1 M sodium nitrate (NaNO3) buffer solution. Equal amounts of the individual standards were mixed. The mixture was filtered through the membrane (direct flow) using a high-vacuum pump (Edwards Vacuum Ltd). The permeate and the mixture were compared using gel permeation chromatography.

[0064] Thus, for example, the MWCO of a membrane that exhibits a minimum rejection of 95% for a 1400 kDa dextran standard molecule can be classified as 1400 kDa.

[0065] If the two methods described herein for determining pore size give different results, the results obtained by the fluorescence readout are conclusive.

[0066] The pores of a material may be arranged so that the material is permeable, partially permeable, or impermeable. If essentially all of the pores of a material have dead ends, the material is impermeable. In contrast, if essentially all of the pores of a material have open ends, i.e., if the pores are interconnected, the material is considered permeable. Consequently, if some of the pores have dead ends, the material is considered partially permeable.

[0067] In an advantageous embodiment, the present invention provides a microporous polymeric structure in which at least 90% of the pores in the porous region are interconnected.

[0068] The porosity, i.e., the volume of pores relative to the total volume of the structure, can be varied within wide limits. The materials of the present invention exhibit a porosity in the range of 10 to 95% by volume, preferably 20 to 90% by volume. The porosity may be determined by porosimetry.

[0069] The surfaces of the aforementioned nanoparticles and / or microparticles may be functionalized. Surface functionalization of nanoparticles and / or microparticles can be achieved using surface functionalization reagents and techniques known to those skilled in the art. Suitable coating materials for the particles can be selected from acid anhydrides such as polymaleic anhydride acids (PMAH), their homopolymers as well as copolymers containing PMAH and mixtures of PMAH, carboxylic acids such as C6-34 carboxylic acids, and mixtures of carboxylic acids. In the context of the present invention, PMAH can be linear or branched. Furthermore, copolymers containing PMAH can also contain other functional groups such as alkane functional groups, alkene functional groups, etc. In the context of the present invention, carboxylic acids can be linear or branched. Furthermore, carbocyclic acids may contain one or more double bonds. The term carboxylic acid further includes monocarboxylic and dicarboxylic acids. Suitable carboxylic acids are selected from the group of naturally occurring fatty acids such as stearic acid and naturally occurring dicarboxylic acids such as pimelic acid or sebacic acid. They may further be selected from the group of alkyl-aryl-alkoxysilanes, aryl-alkoxysilanes, alkyl-alkoxysilanes, and mixtures of such silanes. In the context of the present invention, these silanes may be selected from the group of trialkoxysilane derivatives, dialkoxysilane derivatives, and monoalkoxysilane derivatives. Furthermore, these silane derivatives may be cyclic or linear, thus including the corresponding oligomers. Suitable silanes include those of the formula (C 2~16 ) alkyl) Si(OMe)3, ((C2-C 16 ) alkyl) Si(OEt)3, ((C2-C 16 ) alkyl)2·Si(OMe)2, (C2-C 16) alkyl)2·Si(OEt)2 and the corresponding optionally substituted phenyl group-containing derivatives, such as (C2-C 16 )alkyl)-Ph·Si(OMe)2. In the case of aryl-silanes, one or more of the alkyl groups is replaced with at least one phenyl or substituted phenyl group.

[0070] In a preferred embodiment of the method disclosed herein, at least one of the first and second compositions further comprises plain or functionalized fibers, which on the one hand improve the mechanical properties of the final microporous polymer structure and on the other hand serve to adjust the rheological properties of the composition, for example, to slow down deliquescence or dripping after application or to enhance the shape retention of the applied composition.

[0071] In a preferred embodiment of the method disclosed herein, the second composition comprises the at least one second polymer and, optionally, one or more additives, which may be selected from the group consisting of surfactants, polymerization initiators, stabilizers, crosslinkers, wetting agents, thickeners, hardeners, leveling agents, film flow agents, film uniformity agents, anti-foaming agents, anti-orange peel agents, and combinations thereof.

[0072] In a preferred embodiment of the methods disclosed herein, the first composition comprises: - 1 to 25% of at least one first polymer; 50% to 99% of at least one solvent for the first polymer; 0.5 to 40% of one or more nanoparticles and / or microparticles, - 0 to 5% of additives, and preferably consisting thereof, Each is based on the total weight of the first composition.

[0073] Additionally or alternatively, the second composition comprises: - 1 to 35% of at least one second polymer; 50% to 99% of at least one solvent for the second polymer; - 0 to 40% of one or more nanoparticles and / or microparticles, - 0 to 5% of additives, and preferably consisting thereof, Each is based on the total weight of the second composition.

[0074] This object is further achieved by a microporous polymer structure obtainable by the method disclosed herein. The microporous polymer structure includes a top surface and a bottom surface and has a thickness between the top surface and the bottom surface. The microporous polymer structure further includes at least one porous region formed from a first composition and a substantially non-porous support structure formed from a second composition, the substantially non-porous support structure extending across at least a portion of the thickness between the top surface and the bottom surface. The porous region includes an anisotropic distribution of pore sizes from the top surface to the bottom surface along the thickness direction between the top surface and the bottom surface.

[0075] Such microporous polymer structures are characterized by both high filtration performance and high mechanical strength. The microporous polymer structure may, in particular, be a membrane. The method disclosed herein for obtaining a microporous polymer structure is reflected in the different properties of the microporous polymer structures disclosed herein, namely, flow rate and test particle retention, compared to microporous polymer structures known from the prior art. Flow rate can be evaluated by measuring the amount of water passing through a defined membrane area within a given time frame and a given inlet pressure. Particle retention can be evaluated by filtering a challenge solution containing fluorescent polymer beads of known size, followed by fluorescence analysis as described above.

[0076] In a preferred embodiment of the microporous polymer structure disclosed herein, the pore size at the top surface is in the relatively small pore size range of 5 nm to 5,000 nm, and the pore size at the bottom surface is in the relatively large pore size range of 500 nm to 50,000 nm, so that the pore size at the thickness between the top and bottom surfaces is in the pore size range of 5 nm to 5,000 nm.

[0077] In preferred embodiments of the microporous polymeric structures disclosed herein, the porous region has a porosity of between 10 volume percent and 90 volume percent, based on the total volume of the porous region.

[0078] In preferred embodiments of the microporous polymeric structures disclosed herein, the porous region comprises at least 40% of the total volume of the microporous polymeric structure and the non-porous support structure comprises up to 60% of the total volume of the microporous polymeric structure. Additionally or alternatively, the porous region extends over at least 40% of the total area of ​​the coated substrate and the non-porous support structure extends over up to 60% of the total area of ​​the coated substrate.

[0079] In preferred embodiments of the microporous polymeric structures disclosed herein, the substantially non-porous support structure is an integral part of the microporous polymeric structure, which in the context of the present invention is understood to mean that at least a portion of the support structure is surrounded on all accessible sides by porous regions.

[0080] Such microporous polymer structures can be particularly stable and particularly self-supporting. In a preferred embodiment of the microporous polymer structure disclosed herein, the substantially non-porous support structure comprises a plurality of webs, wherein a first set of webs are arranged substantially parallel to one another. Such structures can be manufactured particularly efficiently and with high throughput in a continuous process by maintaining one or more means for applying the second composition in a fixed relationship relative to one another and to a moving substrate. As an example, a manifold having a number of outlet openings corresponding to the number of parallel webs forming the substantially non-porous support structure can be used in conjunction with a moving substrate.

[0081] Optionally, the second set of webs is arranged substantially perpendicular to the webs belonging to the first set of webs. Thus, in the latter alternative, the non-porous support structure webs are arranged in a checkerboard or diamond pattern. Such a support structure can be particularly easily produced by using two reciprocating means, such as two movable outlets or nozzles, for applying the second composition laterally to the moving substrate. Such a structure can be produced particularly efficiently and with high throughput in a continuous process.

[0082] An embodiment of a microporous polymer structure comprising webs may include at least two webs forming boundary webs that bound the microporous polymer structure on at least two opposing sides. The boundary webs extend across the entire thickness of the porous region. Preferably, the boundary webs close the edges of the microporous polymer structure. In the case of a substantially planar microporous polymer structure, such as a substantially planar membrane, this means that the boundary webs surround the entire membrane in that plane. In the same embodiment, at least some of the webs disposed between the boundary webs extend across a portion of the thickness (d) of the porous region. Furthermore, substantially all of the webs are interconnected.

[0083] This object is further achieved by a filtration device comprising at least one microporous polymer structure as disclosed herein, attached to the filtration device via a non-porous support structure for the microporous polymer structure.

[0084] The filtration device may be a filter housing or a textile. Membrane preparation The general procedure for preparing the microporous polymer structures disclosed herein is as follows: Polysulfone and polyvinylpyrrolidone (1:1) were mixed with N,N-dimethylacetamide and calcium carbonate (2:1 ratio of particles to polymer) to obtain a concentration of 32.6 wt.%. The mixture was then milled in a ball mill (WAB Dyno®-Mill Multi Lab, 10 rpm pumping speed and 3800 U / min milling rotations using 2 mm ZrO2 milling beads) to obtain the first composition. The second composition was prepared by mixing polysulfone and polyvinylpyrrolidone (1:1) with N,N-dimethylacetamide to obtain a concentration of 13.9 wt.%. Both mixtures were simultaneously cast in a continuous pilot coater (Coatema GmbH, SC19) using a doctor blade setting. The basket holding the casting solution was divided into three segments: a central wide segment containing the first composition and two smaller segments containing the second composition adjacent to either side of the wide segment. The membrane was cast onto a PET support layer at a line speed of 0.1 m / min. The layer was then heated from below at 80°C for 4 minutes, followed by drying at 110-150°C for 10 minutes. The resulting composite was then placed in diluted sulfamic acid for 5 minutes to remove the template. The resulting membrane 1 was then washed with deionized water and dried in air for 2 hours. The resulting interface between the porous region 2 formed from the first and second compositions, respectively, and the non-porous support structure 3 was confirmed by scanning electron microscopy (Nanosem 450, FEI), as seen in Figures 6a and 6b.

[0085] The present invention will be better understood with reference to the following description of preferred embodiments and the accompanying drawings, in which the same reference numerals are used to denote the same or equivalent features among different embodiments and examples. Briefly, the present invention is as follows: [Brief explanation of the drawings]

[0086] [Figure 1] 1 is a flow chart illustrating the sequence of one embodiment of a method for producing a porous polymer structure disclosed herein. [Figure 2a]FIG. 1 is a schematic diagram of steps b) to h) of the method disclosed herein. [Figure 2b] FIG. 2 is a further schematic diagram of steps b) to h) of the method disclosed herein. [Figure 3a] FIG. 1 is a top view of a microporous polymer structure precursor on a substrate. [Figure 3b] 3b is a cross-sectional view of the precursor shown in FIG. 3a taken along line AA in FIG. 3a. [Figure 3c] 3b is a cross-sectional view of the precursor shown in FIG. 3b along line BB in FIG. 3b. [Figure 4] 1 is a cross-sectional view of a freestanding embodiment of a microporous polymer structure disclosed herein. [Figure 5] 1 is a cross-sectional view of a further embodiment of a microporous polymer structure disclosed herein. [Figure 6a] 1 is an SEM image of a cross section of a microporous polymer structure obtained by the method disclosed herein. [Figure 6b] 1 is an SEM image of a cross section of a microporous polymer structure obtained by the method disclosed herein. DETAILED DESCRIPTION OF THE INVENTION

[0087] FIG. 1 shows a flow chart of one embodiment of a method according to the present invention for producing a porous polymer structure 1, which may be a membrane. In this example, the method includes step a) of providing a substrate 4. The substrate 4 may be a porous or non-porous substrate, particularly as disclosed herein, and may be essentially flat, i.e., have a two-dimensional shape, or may be non-flat, i.e., have a three-dimensional shape. In step b), a first composition 5 is provided, which includes a first polymer, at least one solvent for the first polymer, and one or both of nanoparticles and microparticles dispersed therein. Subsequently, in step d), the first composition 5 is applied to the surface 4a of the substrate 4 to form a first coating layer 7. The application of the first composition to each substrate surface 4a can be carried out by any method known to those skilled in the art, depending on the properties, particularly the rheological properties, of the first composition 5. For example, the first composition 5 may be applied to a predetermined thickness using a squeegee. Optionally, the first coating layer 7 may be subjected to an atmosphere, such as a drainage stream or reduced pressure, that promotes evaporation of at least one solvent for the first polymer, as indicated by the dashed arrow e). Note that optional step e) is not the same as the following step f), which involves phase separation of the first coating layer 7 from one side of the first coating layer 7 to obtain a phase-separated first coating layer 7'. Phase separation may be initiated, in particular, from the substrate side, as will be described in more detail below. Before or after step f), a second composition 6 is provided in step c), which includes a second polymer and, optionally, at least one solvent for the second polymer. In step g), the second composition 6 is applied in a patterned manner to the same substrate surface 4a as the previous first composition 5. Of course, it is also conceivable that the first composition 5 and the second composition 6 are applied to the substrate surface 4a essentially simultaneously, i.e., steps d) and g) are performed in parallel. Additionally or alternatively, the second composition 6 may also be applied in step g) onto, i.e. at least partially on, the phase-separated first coating layer 7′ obtained in step f).The second composition 6 (i.e., the future non-porous support structure) and the first composition 5 (i.e., the future porous region) are disposed on the substrate 4 so that they form a common interface, meaning that the first composition 5 and the second composition 6 are applied so that they contact each other. In step h), the second composition 6 is physically hardened or cured to obtain the non-porous support structure 3 of the microporous polymer structure 1. Subsequently, in step i), the nanoparticles and / or microparticles contained in the phase-separated first coating layer are dissolved with an aqueous solution to obtain the porous region 2 of the microporous polymer structure 1. The microporous polymer structure thus obtained thus has at least one porous region 2 and a substantially non-porous support structure 3 configured to support the at least one porous region 2, as described in further detail below. In optional step j), indicated by the dotted arrow, the microporous polymer structure 1 including the porous region 2 and the substantially non-porous region 3 acting as a support structure for the porous region 2 may be dried. In the example shown in Figure 1, the method further comprises step k) of removing the microporous polymer structure 1 from the substrate 4 to obtain a free-standing microporous polymer structure 1'. As is clear from Figure 1, step k) is performed after any of steps g) to j).

[0088] FIG. 2a is a schematic diagram of steps b) through h) of one embodiment of the method disclosed herein. In the upper left of FIG. 2a, a first composition 5 is provided in step b), which is prepared by adding a first polymer 5a, a solvent 5b for the first polymer 5a, and a mixture of nanoparticles and microparticles 5c to a suitable container, such as a beaker or a stirring kettle. In the upper right of FIG. 2a, a second composition 6 is provided in step c), which is prepared by adding a second polymer 6a and a solvent 6b for the second polymer 6a. As with step b), any suitable container may be selected for dissolving the second polymer 6a in the solvent 6b. However, it is not explicitly required that the second polymer 6a be provided dissolved in a solvent. For example, it is contemplated that the second polymer 6a and any additives contained therein or added thereto essentially constitute the second composition 6, and that the second composition 6 is applied in a molten state. The subsequent steps of applying the first and second compositions to the same surface side 4a of the substrate 4 (steps d) and g), the step of phase separation in the first composition to obtain a phase-separated first coating 7′ (step f), and the step of physically hardening or curing the second composition 6 to obtain a non-porous support structure 3 (step h) are not shown in detail in FIG. 2a, but their implementations will be understood by those skilled in the art. If the second composition 6 is applied as a melt provided, for example, by an extruder, the formation of the support structure 3 occurs as a result of solidification of the second composition 6 during cooling. In the example shown in the lower part of FIG. 2a, the precursor of the microporous polymer structure still contains salt particles 5c of the first composition 5, which can be washed away in step i) to produce the microporous polymer structure. In the example shown in the lower part of FIG. 2a, the microporous polymer structure obtained after washing away the precursor and, optionally, the salt particles, is also supported by the substrate 4.

[0089] Figure 2b is a further schematic illustration of steps b) to h) of one embodiment of the method disclosed herein. Process steps b) to h) shown in Figure 2b correspond to the process steps already described in Figure 2a, except that the second composition 6 is not only applied in a patterned manner to the same surface 4a of the substrate 4 as the first composition 5, but is also applied to a phase-separated first coating layer 7'.

[0090] FIG. 3a is a schematic top view of the upper surface 1a of one embodiment of a microporous polymer structure 1 on a substrate 4. Both a first composition and a second composition (not shown) were applied to one side, i.e., surface 4a, of the substrate 4. The microporous polymer structure 1 shown in FIG. 3a includes a substantially non-porous support structure formed from the second composition, the support structure including a plurality of webs 3a-3c. The first set of webs 3a are arranged substantially parallel to one another. The most spaced-apart webs of the first set of webs 3a are border webs 3c, which bound the microporous polymer structure 1 on two opposing sides and extend throughout the thickness (d) of the porous region 2, as shown and described in FIGS. 3b and 3c. Additionally, the second set of webs 3b are arranged substantially perpendicular to the webs of the first set of webs 3a. The porous region 2 is at least partially separated by webs 3a and 3b.

[0091] FIG. 3b shows a cross-section of the microporous polymer structure 1 shown in FIG. 3a along line AA in FIG. 3a. As can be seen from this figure, the porous polymer structure 1 has a thickness d between its top surface 1a and its bottom surface 1b, with the bottom surface 1b being in contact with the surface 4a of the substrate 4. The thickness d denotes the extent of the porous region 2. The porous region 2 includes an anisotropic distribution of pore sizes from the top surface 1a to the bottom surface 1b along the thickness direction d between the top surface 1a and the bottom surface 1b (due to the schematic representation of the figure, the anisotropic distribution of pore sizes is not shown). As can be seen from the cross-section shown in FIG. 3b, the boundary web 3c extends over the entire thickness d of the porous region 2, while the web 3a, which belongs to the first set of webs and is disposed between the boundary webs 3c, extends over a portion of the thickness d between the top surface 1a and the bottom surface 1b, i.e., over a portion of the thickness d of the porous region 2.

[0092] FIG. 3c shows a cross-section of the microporous polymer structure 1 shown in FIG. 3a along line BB in FIG. 3a. The cross-section passes through web 3b of a second set of webs, which is arranged substantially perpendicular to the web belonging to the first set of webs 3a. As can be seen from the diagram shown in FIG. 3c in conjunction with FIG. 3a, all webs 3a-3c are interconnected and thus together form a substantially non-porous support structure 3 configured to support the porous region 2. In addition to the support function of the support structure 3, another advantage of the microporous polymer structure 1 disclosed herein is that the support structure 3, and in particular the border web 3c, serves as a suitable sealing area for securing and reliably sealing the microporous polymer structure 1 within the filter housing. Such fastening to the support structure 3, which is much more heat-resistant than the porous region 2, can be performed, for example, by welding, without adversely affecting the porous region 2. The non-porous support structure 3 and the porous region 2 are positioned on the substrate 4 so that the non-porous support structure 3 and the porous region 2 form a common interface, i.e., they are in contact with each other. Optional removal of the microporous polymer structure 1 from the substrate 4 results in a free-standing microporous polymer structure.

[0093] FIG. 4 shows a cross-section of a freestanding embodiment of the microporous polymer structure 1 disclosed herein. In this particular embodiment, the substantially nonporous support structure 3 is an integral part of the microporous polymer structure 1 because at least a portion of the support structure 3, i.e., the web 3a, is surrounded on all accessible sides by the porous region 2. In other words, at least a portion of the support structure 3 is embedded in the porous region 2. This configuration can be achieved by first applying a first coating layer of a first composition to the substrate, as described above, and then applying a second composition to the first coating layer. An additional coating layer of the first composition is applied before phase separation occurs in the first coating layer. The remaining steps of the method described herein can be similarly performed for this embodiment. The web 3a serves as a reinforcing framework for the entire microporous polymer structure 1, enhancing its mechanical stability. As can be seen in FIG. 4, the microporous polymer structure 1 can be attached to a surface, such as a filter housing of a filtration device 10, by its border web 3c.

[0094] 5 shows a cross-section of a further embodiment of a microporous polymer structure 1 disclosed herein. In this particular example, the microporous polymer structure 1 is attached to a textile substrate 9 via attachment points 8 between the textile substrate 9 and at least some of the webs 3a of the substantially non-porous support structure 3. Attachment of the microporous polymer structure 1 to the textile 9 can occur before or after removing the support 4 used in the manufacturing methods disclosed herein (not shown). Again, the thickness d between the top and bottom surfaces of the microporous polymer structure 1 corresponds to the thickness of its porous region 2.

Claims

1. A method for producing a microporous polymer structure (1), in particular a membrane, having at least one porous region (2) and a substantially non-porous support structure (3) configured to support said at least one porous region (2), said method comprising the steps of: a) providing a substrate (4); b) providing a first composition (5) comprising a first polymer (5a), at least one solvent (5b) for said first polymer, and one or both of nanoparticles and microparticles (5c) dispersed within said first composition (5); c) providing a second composition (6) comprising a second polymer (6a) or a precursor of a second polymer (6a); d) applying the first composition (5) to the surface (4a) of the substrate (4) to form a first coating layer (7); f) performing phase separation in the first coating layer (7) to obtain a phase-separated coating layer (7'); g) applying said second composition (6) in a patterned manner to the same surface (4a) of said substrate (4) and / or to said phase-separated first coating layer (7'); h) physically hardening or curing the second composition (6) applied in step g) to obtain said non-porous support structure (3); i) dissolving the nanoparticles and / or microparticles (5c) with a washing solvent to obtain the porous region (2), The method, wherein the non-porous support structure and the porous region are disposed on the substrate so as to form a common interface, and the phase separation in the first coating layer (7) in step f) is carried out from one side of the first coating layer (7).

2. 2. The method of claim 1, wherein the second composition (6) provided in step c) further comprises at least one solvent (6b) for the second polymer (6a).

3. e) subjecting said first coating layer (7) to an atmosphere that promotes evaporation of said at least one solvent (5b) for said first polymer (5a), 3. The method of claim 1, wherein step e) is performed after step d) and before step f).

4. 10. The method of any one of the preceding claims, wherein the washing solvent is an acidic aqueous solution.

5. 10. The method according to any one of the preceding claims, further comprising the step of j) drying the microporous polymer structure (1) obtained after step i).

6. 10. The method according to any one of the preceding claims, wherein the separation of the first coating layer (7) in step f) is carried out from the side of the substrate (4).

7. k) removing the microporous polymer structure (1) from the substrate (4) to obtain a free-standing microporous polymer structure (1'); 10. The method of any one of the preceding claims, wherein step k) is performed after any one of steps g) to j).

8. 10. The method of any one of the preceding claims, wherein steps d) and g) are performed simultaneously, followed by step f).

9. 10. The method according to any one of the preceding claims, wherein the phase separation in step f) is carried out by applying heat above 40°C to one side of the first coating layer (7), preferably from the side of the substrate (4).

10. 10. The method according to any one of the preceding claims, wherein the precursor of the second polymer (6a) is at least one of a radiation-curable monomer and a radiation-curable oligomer, and wherein curing of the second composition (6) in step h) is carried out by radiation curing using ultraviolet (UV) light, preferably ultraviolet light having a wavelength between 280 nm and 400 nm, or high-energy electrons from an electron-beam (EB) source.

11. The nanoparticles and / or microparticles (5c) are oxides, carbonates, sulfates, halides, nitrates and phosphates, preferably oxides and carbonates, most preferably calcium carbonate (CaCO ３ ), barium carbonate (BaCO ３ ), strontium carbonate (SrCO ３ ), sodium carbonate (Na ２ CO ３ ), potassium carbonate (K ２ CO ３ ), sodium chloride (NaCl), zinc oxide (ZnO) and calcium oxide (CaO), and / or said nanoparticles and / or microparticles (5c) have a particle size of 1 to 5000 nm, preferably 5 to 600 nm, determined by laser diffraction spectroscopy in combination with polarization intensity differential scattering (PIDS) technique.

12. 12. The method according to claim 11, wherein the surface of the nanoparticles and / or microparticles (5c) is functionalized.

13. 13. The method according to any one of claims 1 to 12, wherein the second composition (6) consists of the at least one second polymer (6a) and, optionally, one or more additives (6c), in particular one or more additives selected from the group consisting of surfactants, polymerization initiators, stabilizers, crosslinkers, wetting agents, thickeners, hardeners, leveling agents, film flow agents, film uniformity agents, antifoaming agents, and anti-orange peel agents.

14. A microporous polymer structure (1), in particular a membrane, obtainable by the method according to any one of claims 1 to 13, - a top surface (1a) and a bottom surface (1b), - the thickness (d) between said top surface (1a) and said bottom surface (1b), - at least one porous region (2) formed from a first composition (5), a substantially non-porous support structure (3) formed from a second composition (6), A microporous polymer structure (1), wherein the porous region (2) comprises an anisotropic distribution of pore sizes from the top surface (1 a) to the bottom surface (1 b) along a thickness direction (d) between the top surface (1 a) and the bottom surface (1 b), and the substantially non-porous support structure (3) extends over at least a portion of the thickness (d) between the top surface (1 a) and the bottom surface (1 b).

15. 15. The microporous polymer structure (1) according to claim 14, wherein the pore size of the top surface (1 a) is in a relatively small pore size range of 5 nm to 5000 nm, the pore size of the bottom surface (1 b) is in a relatively large pore size range of 500 nm to 50000 nm, and the pore size at the thickness (d) between the top surface (1 a) and the bottom surface (1 b) is in a pore size range of 5 nm to 5000 nm, and the pore size is determined by fluorescence reading from fluorescently labeled polystyrene or silica microspheres or by dextran rejection tests.

16. 16. The microporous polymer structure (1) according to claim 14 or 15, wherein the porous region (2) constitutes at least 40% and the non-porous support structure (3) constitutes at most 60% of the total volume of the microporous polymer structure, and / or the porous region (2) extends over at least 40% and the non-porous support structure (3) extends over at most 60% of the total area of ​​the coated substrate, each based on the total area of ​​the coated substrate.

17. A microporous polymer structure (1) according to any one of claims 14 to 16, wherein said substantially non-porous support structure (3) is an integral part of said microporous polymer structure (1).

18. 18. The microporous polymer structure (1) according to any one of claims 14 to 17, wherein said substantially non-porous support structure (3) comprises a plurality of webs, a first set (3a) of webs being arranged substantially parallel to one another and, optionally, a second set (3b) of webs being arranged substantially perpendicular to the webs belonging to said first set (3a) of webs.

19. 19. The microporous polymer structure (1) of claim 18, wherein at least two of the webs are border webs (3c) that border the microporous polymer structure (1) on at least two opposite sides and extend over the entire thickness (d) of the porous region (2), preferably the border webs (3c) close the edges of the microporous polymer structure, at least some of the webs arranged between the border webs (3c) extend over part of the thickness (d) of the porous region (2), and substantially all of the webs are interconnected.

20. A filtration device (10), in particular a filter housing or textile, comprising at least one microporous polymer structure (1) according to any one of claims 14 to 17, wherein said at least one microporous polymer structure (1) is attached to said filtration device (10) via said non-porous support structure (3) of said microporous polymer structure (1).

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