Abstract: Microporous diaphragms adapted for wet-consolidation with composite cathodes for use in electrolytic cells, e.g., chlorine/soda electrolysis cells, comprise a sintered, fluoropolymer microconsolidated asbestos-based microporous fibrous sheet material, such sheet material including from 3% to 35% by weight of fluoropolymer binder, from 1% to 50% by weight of a uniformly distributed gel of an oxohydroxide of at least one metal of Groups IVA, IVB, VB and VIB of the Periodic Table or of the lanthanide or actinide series thereof, and from 20% to 95% by weight of fibers, at least 1% by weight of such fibers being asbestos fibers.

Abstract: A novel method for making a composite separation membrane, and the product of that method. This novel method includes applying one or more perfluoroethers to the surface of a microporous fiber or film made of a polymer such as PAN, and subsequently coating that fiber or film surface with a layer of selective material. This method provides a more permeable composite membrane than would be obtained by coating a fiber or film that had not been pre-wetted with perfluoroether.

Abstract: A process to synthetize zircon as an ultra thin coating and comprising: (A) mixing an alcoholic sol resulting from hydrolysis of a silicon alkoxide with an alcoholic solution of a chelated zirconium compound and in the presence of and with a doping agent, until a homogenous mixed sol is obtained; (B) forming a matured sol containing colloidal particles and/or the polymeric entities from the mixed sol; (C) forming a coating of the matured sol on a microporous substrate; (D) drying slowly the sol coating into a gel coating free of flaws; and (E) firing the gel coating at a temperature of 900.degree. to 1500.degree. C. to form an ultra thin zircon layer. Use of the zircon layer obtained above as an ultrafiltration membrane or as a protective coating.

Abstract: A hydrophilic porous membrane is obtained by covering porous membrane substrate with a non-ionic, amino-acid-based or non-ionic fluorine-based surface active agent. For the covering, the porous membrane substrate is immersed in a solution containing the surface active agent and then drying the membrane substrate. A different hydrophilic porous membrane is obtained by providing the surfaces of a porous membrane substrate and inner pore surfaces with a polar group and then covering the membrane substrate with a hydrophilic polymer film. For this covering, after introduction of the polar group to the surfaces of the porous membrane substrate and inner pore surfaces, the membrane substrate is immersed in a solution containing a hydrophilic substance and then dried.

Abstract: A method for permformation of microporous ceramic membranes onto a porous support includes placing a colloidal suspension of metal or metal oxide particles on one side of the porous support and exposing the other side of the porous support to a drying stream of gas or a reactive gas stream so that the particles are deposited on the drying side of the support as a gel. The gel so deposited can be sintered to form a supported ceramic membrane useful for ultrafiltration, reverse osmosis, or molecular sieving having mean pore sizes less than 100 Angstroms.

Abstract: A method of forming a polymer film having controlled physical and chemical characteristics, wherein a plume of nebulized droplets of a polymer or polymer precursor is directed toward a substrate from a converging/diverging nozzle having a throat at which the polymer or a precursor thereof is introduced and an exit from which the nebulized droplets of the polymer or precursor thereof leave entrained in a carrier gas. Relative movement between the nozzle and the substrate is provided to form a polymer film. Physical and chemical characteristics can be controlled by varying the deposition parameters and the gas and liquid chemistries. Semipermeable membranes of polyphosphazene films are disclosed, as are a variety of other polymer systems, both porous and non-porous.

Abstract: A method of producing a flat, reinforced article with micro-openings is described wherein at least one reinforcing layer is applied to a basic layer. To be able to carry out such a method in an easy and inexpensive way, the following steps should be taken: Coating a prefabricated basic layer at both sides with a radiosensitive resist in such a way that the resist fills the micro-openings, irradiating the basic layer provided with the resist from one side in such a way that the radiation passes through the resist in the micro-openings, removing the resist from the basic-layer regions to be provided with the reinforcing layer, applying the reinforcing layer and subsequently removing the remaining resist.

Abstract: A water-vapor permeable, waterproof coated fabric having a fibrous base fabric, and a porous film coated on one side of the base fabric. The porous film comprises a synthetic polymer composed mainly of a polyurethane resin and inorganic fine particles having a mean particle diameter of not more than 0.1 .mu.m. In the porous film, microcells intercommunicate in the thicknesswise direction of the film to form a honeycomb skin core structure having a diameter of 1 to 20 .mu.m. The porous film has a multiplicity of micropores having a diameter of not more than 1 .mu.m. The coated fabric has waterproof and water-vapor permeability characteristics sufficient to meet such performance characteristics required in various applications, such as rainwears, military garments, and sportswears.

Abstract: Disclosed is a process for producing a mineral membrane on a mineral support, involving the production of a dispersion of a filler and a resin, depositing this dispersion onto a support so as to form a layer, followed by the thermal treatment of the support covered with the layer, to obtain an asymmetric thin membrane. A fluid dispersion is prepared of a filler, a water-soluble solvent and a resin insoluble in water but soluble in the organic solvent, and, after coking, to a coke content higher than 20% by weight, it is deposited onto the mineral support, all or some of the solvent is displaced in order to precipitate the resin, and the resin and, if appropriate, the support are coked.

Abstract: A deodorant porous polymer having excellent deodorant effects is provided. The deodorant porous polymer is in the shape of substantially uniform particulates or an aggregate thereof, and is obtained by the hydrolysis and polycondensation of at least one alkoxide selected from the group consisting of inorganic alkoxides and metal alkoxides through the use of a sol-gel method. Also provided is a deodorant fibrous material that includes a fibrous substrate and a deodorant porous polymer as mentioned above, which is combined with the fibrous substrate in the physically-combined state and/or the chemically-combined state.

Abstract: A composite or asymmetric membrane for separating and concentrating a particular component from a mixture of gases. The asymmetric membrane is of a fluorine-containing aromatic polyimide resin of the 6FDA type. The composite membrane has a thin film of an elastomeric polymer formed on a supporting film of a fluorine-containing aromatic polyimide resin of the 6FDA type.

Abstract: To a first organic liquid which has dissolved therein a flurocarbon polymer, e.g. 5 to 50% w/w e.g. PVDF, is added a second, compatible, non-solvent organic liquid in an amount (e.g. 1-50%) w/w such as to leave the polymer in solution. The mixed solution is applied to a leather or fabric substrate and heated e.g. at 60.degree. C. to 150.degree. C. for 2-15 minutes. Polymer deposits as the first liquid evaporates and pores form therein as the second liquid evaporates from the deposit. The anchored layer produced repels liquid water, but allows passage of water vapor.

Abstract: A composite or asymmetric membrane for separating and concentrating a particular component from a mixture of gases. The asymmetric membrane is of a fluorine-containing aromatic polyimide resin of the 6FDA type. The composite membrane has a thin film of an elastomeric polymer formed on a supporting film of a fluorine-containing aromatic polyimide resin of the 6FDA type.

Abstract: A leather-like material having a soft feed and a high water vapor permeability comprises a substrate of a fiber aggregate and a microporous grain layer mainly comprising a polyurethane elastomer and having an average thickness between 20 .mu.m and 300 .mu.m, preferably between 20 .mu.m and 200 .mu.m, more preferably 20 .mu.m and 100 .mu.m. The grain layer has an inner layer portion permeating partly into interstices of the fiber aggregate and bonding thereto, a topside having been coagulated to set up with a flat and smooth, or animal skin-like, grain appearance and micropores having an average pore diameter gradient of from at least 4 .mu.m in the inner layer portion to at most 3 .mu.m in the surface layer portion. The leather-like material is characterized by a water vapor permeability of from 1 to 30 mg/cm.sup.2.hr and a Gurley stiffness ratio of article to substrate of at most 1.5.

Abstract: An asymmetric semipermeable membrane and processes for the manufacture thereof are disclosed. The membrane comprises at least one hydrophobic polymer and at least one copolymer based on acrylonitrile, at least one sulphonic monomer which is optionally salified, and optionally at least one non-ionic, ionizable, olefinically unsaturated monomer. The membrane is useful in the treatment of biological fluids such as plasma or blood, especially using plasmapheresis, or with the aid of an artificial kidney using hemodialysis and/or ultrafiltration.

Abstract: An aromatic polyimide double layered hollow filamentary membrane having an excellent heat resistance, chemical resistance, pressure-resistance, and gas-permeating and separating properties comprises (A) an aromatic imide polymer hollow filamentary microporous inner layer and (B) an aromatic imide polymer tubular filamentary asymmetric outer layer composed of (a) tubular filamentary microporous intermediate layer covering and united with the outside surface of the inner layer (A) and (b) a thin dense outside surface layer covering and united with the intermediate layer (a).

Abstract: The method of the present invention for separating pyrogens includes passing a pyrogen-containing liquid through a zirconium oxide membrane on a ceramic support. The membrane on ceramic support preferably includes a porous sintered zircondium oxide membrane on alpha-alumina support.

Abstract: Waterproof, moisture-vapor-permeable urethane-coated fabrics with durable antimicrobial properties that remain after repeated launderings are prepared by incorporating bioactive silyl quaternary ammonium salts into the polyurethane elastomer solvent solution that forms a microporous polyurethane layer by the wet coagulation method on a base fabric.

Abstract: A liquid active substance-containing membrane having an anisotropic structure comprising (a) a polymeric cellular layer containing a myriad of minute closed cells and septa thereof and (b) a dense thin layer covering the surface of the cellular layer, wherein the minute cells contain therein a liquid active substance having a limited solubility in the polymer at normal temperature. The membrane of the present invention can be advantageously used to release a liquid active substance such as pheromones and pesticides at a substantially constant, controlled rate over a long period of time.

Abstract: A process for preparing microporous inorganic membranes comprising mixing a sol comprised of inorganic colloidal particles dispersed in a liquid medium with an organic polymeric film forming material dissolved in a suitable solvent. The liquid medium of the sol, the organic polymeric film forming material, and the solvent being selected such that:(1) the liquid medium of the sol and the solvent are miscible,(2) the organic polymeric film forming material is soluble in the solvent and(3) the organic polymeric film forming material is insoluble in the liquid medium of the sol.The mixture is applied to a porous support and the organic film forming material is allowed to separate from the solvent/sol to form a phase-separated coating. The phase-separated film coated support is dried to remove the solvent, and heated at a temperature sufficient to burn off the organic polymeric film forming material but below the sintering temperature, thereby leaving a microporous inorganic membrane.

Abstract: Strong and durable alpha alumina ultrafiltration membranes with effective separating layers having effective pore diameters less than about 50 nm, and particularly at almost any point within the range of about 10 to about 50 nm, can be produced by seeding boehmite sols with appropriate seeds, such as very fine alpha alumina with a specific surface area of more than 100 sq. m. per g, gelling a thin layer of the sol by contact with a microfilter support, drying the gel, followed by controlled heating of the coated support both to convert the boehmite to alpha alumina and to simultaneously control the effective pore diameter of the resultant membrane.

Abstract: A process for producing a composite membrance in which a sulphonated polymer is appled to the surface of a porous substrate, treating the polymer, in situ, on the substrate with cations of a polyvalent metal and converting the treated coating into a water insoluble layer on the support. The polyvalent metal may preferably by aluminum or chromium.

Abstract: Waterproof, moisture-vapor-permeable aromatic urethane-coated fabrics that resist degradation caused by ultraviolet light are prepared by incorporating hindered amine ultraviolet stabilizers into the aromatic urethane elastomer solvent solution that forms a microporous polyurethane layer by the wet coagulation method on a base fabric.

Abstract: The invention relates to a process for the preparation of a coagulated material by impregnating a textile cloth in an impregnating bath containing at least a coagulable polymer latex followed by coagulation in a coagulating bath.The process of the invention is characterized in that the coagulation is carried out from the water phase, whereas the impregnating bath contains a (chemical or physical) foaming agent, wherein foaming occurs simultaneously with the coagulation or immediately thereafter.It is surprisingly found that according to the present process a high quality coagulated material is obtained, which is comparable with the coagulated material, obtained according to conventional processes.

Abstract: The invention relates to a hyperfiltration membrane containing a supporting layer and a separation layer. The membrane is characterized in that the separation layer consists of a crosslinked monomolecular film of molecules, the molecules of the separation layer in the uncrosslinked state being surfactants or surfactant-like lipoids containing at least one hydrophobic chain and at least one hydrophilic group, the hydrophobic chains of these molecules being oriented mainly perpendicularly to the plane of the membrane and parallel to the diffusion direction after crosslinking and the molecules of the separation layer being crosslinked with one another through functional groups in at least one of their hydrophobic chains and/or through functional groups in at least one of their hydrophilic groups.

Abstract: Water-vapor-permeable yet waterproof coated fabrics are prepared by applying a polyurethane resin solvent solution plus flame retardent to a base fabric then immersing the coating to coagulate the resin leaving a thin, microporous coating on the fabric. An acrylic acid thickener system may be included in the resin solvent solution. The resultant microporous coated fabric has a moisture vapor transmission rate of at least 600 g/m.sup.2 /24 hours, a hydrostatic pressure resistance of at least 69 kPa and is resistant to flame.

Abstract: A sulphonated aromatic polymer containing repeating units (Ar-Y) (where Y is SO.sub.2 and/or CO), where at least half of groups Ar contain a group SO.sub.3 M and M is l/m of a polyvalent metal cation in at least 80% of such groups SO.sub.3 M, and where m is the valency of the ion. The polyvalent cation compound is formed by heating the corresponding sulphonic acid or monovalent cation compound with a salt of a polyvalent metal. The polymer is useful as a membrane and the polyvalent metal salt addition and/or the heat treatment may be applied to polymer in membrane form.

Abstract: The invention relates to a coagulable composition, to a process for the preparation of a coagulated material by impregnating a textile cloth in an impregnating bath containing the coagulable composition followed by coagulation in a coagulating bath and to the resulting coagulated material.The process of the invention is characterized in that the coagulation is carried out from the water phase, and the impregnating bath contains a chemical or physical foaming agent, wherein foaming occurs simultaneously with the coagulation or immediately thereafter.It is surprisingly found that according to the present invention a high quality coagulated material is obtained, having properties comparable with the coagulated material obtained according to conventional solvent based processes.

Abstract: Composite ultrafiltration membranes are disclosed which are produced by forming an ultrafiltration membrane structure on a preformed microporous membrane.

Abstract: A waterproof fabric having a high moisture permeability and having an ultra-microporous continuous polymer coating having an average pore diameter in the range of between 50 .ANG. and 0.2.mu., said polymer having a monomer unit containing at least one acid radical selected from carboxyl group, sulfonic acid group, and alkali metal salts thereof.

Abstract: A method of upgrading the selectively of a dry asymmetric permselective membrane comprising a porous barrier layer adjacent to a porous main body, where the barrier layer has an external obverse surface. The method comprises maintaining the barrier layer surface in a drying atmosphere while applying a wetting liquid which is not a solvent for the bulk of the membrane to the obverse surface to wet interstices of the bulk of the membrane, and drying the membrane by continuing the exposure of the external surface of the barrier layer to the drying atmosphere as the wetting liquid moves from the obverse surface through the membrane main body and the barrier layer.

Abstract: The present invention relates to a process for the production of textiles that are coated with polyurethane, in which the material that is to be coated is coated with two oppositely charged aqueous ionic dispersions of polyurethanes that contain no free isocyanate groups and contain covalently bonded, solubility-enhancing ionic groups, dried and optionally waterproofed. Cationic and anionic polyurethane dispersions are preferred in a weight ratio of 1:1, and are applied to the textile material in a two-coat technique, wet-on-wet. In addition, the invention relates to textile material produced in this way, with improved waterproof qualities and the use of such textiles for the production of breathable, water- and wind resistant clothing, industrial textiles, and leather substitutes, all of which are permeable to water vapour.

Abstract: Integral gradient, skinned, submicroscopically porous, anisotropic, hydrophilic, asymmetric polyamide membranes comprising:(a) a first porous polyamide zone obtained from a polyamide solution formulated to give coagulated film with pores of a given size,(b) a fabric support imbedded in the first porous polyamide layer, and(c) a second porous polyamide zone having a skinned outer surface, obtained from a polyamide solution having the same constituents as the solution used to form the first porous polyamide zone but solution post-treated to give pores substantially smaller than those in the first porous polyamide zone, as well as a process for producing such membranes, are disclosed.

Abstract: This invention relates to spreading pastes containing polyurethanes which are prepared from special synthesis components selected from the group of silicone resins, polyethers or polyesters containing aromatic segments or perfluorocarbon resins. The spreading pastes also contain organic solvents and optionally non-solvents for the polyurethanes so that when the coatings are used to coat textile substrates according to the direct or transfer process, the coatings may be cured based on the principle of evaporation coagulation.

Abstract: The invention relates to a process for the production of porous, permeable, mineral membranes.According to this process, on a porous, permeable substrate is formed a thin layer of at least one mineral compound chosen from among the simple or mixed metal oxides, except aluminum oxide and mixed aluminium oxides, simple or mixed metal hydroxides, except aluminium hydroxide and mixed aluminium hydroxides and mixtures thereof on the basis of a suspension in a liquid of colloidal or non-colloidal particles, said compound or a precursor thereof having particle sizes below 10 .mu.m. The suspension is kept in the finely divided state by the continuous application of energy to the reaction medium. The thus obtained membrane is dried and then annealed at a temperature between 400.degree. and 1100.degree. C.The use of a suspension of ultrafine colloidal or non-colloidal particles makes it possible to obviate the compression stage and obtain microporous layers with very small pore radii.

Abstract: A composite semipermeable membrane and a process for preparation thereof are described, wherein said membrane comprises (1) a porous substrate, (2) an ultrathin film as a surface layer formed by polymerization by crosslinking of polyvinyl alcohol and an amino compound having at least two secondary amino groups using a polyfunctional crosslinking reagent capable of reacting with secondary amino groups and hydroxyl groups, and (3) a porous inner layer composed of water insoluble polyvinyl alcohol which is present between the porous substrate and the ultrathin film.

Abstract: Process particularly suitable for artificial leather of the type whereby a porous polyurethane resin matrix containing polyester and/or polyethylene fibers is covered with a compact, pressed polyurethane resin film, and consists of treating the artificial leather in rotary tanning drums, firstly, with a relatively concentrated solution of water and PIROFLAM (registered trade mark) or other similar commercial fireproofing/retarding substance of the type commonly employed for extinguishing forest fires, and, secondly, with a solution of water and softener, e.g. TRIANOL SP (registered trade mark) to which is added an appropriate amount of the same fireproofing/retarding substance used previously on the artificial leather.

Abstract: A method for manufacturing polishing cloths of the class to be used with abrasive powders on a lapping machine is disclosed. The method comprises the steps of impregnating a nonwoven fabric sheet with a solution of polyurethane elastomer, wet-coagulating the impregnated sheet, and heating the resulting microporous composite sheet at a temperature higher than the softening point of the polyurethane elastomer under an essentially uncompressed condition.

Abstract: Water vapor permeable yet waterproof coated fabrics are prepared by applying a polyurethane resin solvent solution to a base fabric then immersing the coating to coagulate the resin leaving a thin, microporous coating on the fabric. An acrylic acid thickener system is included in the resin solution to provide moisture vapor transmission rates of at least 600 g/m.sup.2 /24 hrs and hydrostatic pressure resistance of at least 10 psi.

Abstract: Polymeric microfibrous structures comprised of normally hydrophobic microfibers coated with a cured, precipitated, cationic, thermosetting binder resin or polymer and characterized by being hydrophilic and having a positive zeta potential with enhanced capability for the removal of negatively-charged particulate material in a fluid medium are prepared by a process comprising the steps:(1) combining in a controlled manner a first solution of a water-soluble, non-colloidal, cationic, thermosetting binder resin or polymer and a second solution or dispersion of a precipitating agent to form a stable emulsion or suspension;(2) impregnating the microfibrous structure of normally hydrophobic microfibers with the stable emulsion or suspension to form a fibrous structure wetted with the stable emulsion or suspension; and(3) drying the wetted microfibrous structure and curing the binder resin or polymer.

Abstract: A hydrophilized membrane of a porous hydrophobic material having micropores each defined by a surface at least part of which is coated with a hydrophilizing agent which is solid at about 20.degree. C. and substantially insoluble in water. The hydrophilizing agent is preferably selected from monofatty acid esters of propylene glycol. Also disclosed are processes for hydrophilizing such porous hydrophobic membranes.

Abstract: A method of coating a substrate with a thin film of a polymer of predetermined porosity comprises depositing the thin film on the substrate from a non-gelled solution comprising at least one hydrolyzable metal alkoxide of a polymeric network forming cation, water, an alcohol compatible with the hydrolysis and the polymerization of the metal alkoxide, and an acid or a base, prior to depositing the film, controlling the structure of the polymer for a given composition of the solution exclusive of the acid or base component and the water component, (a) by adjusting each of the water content, the pH, and the temperature to obtain the desired concentration of alkoxide, and then adjusting the time of standing of the solution prior to lowering the temperature of the solution, and (b) lowering the temperature of the solution after the time of standing to about 15 degrees C.

Abstract: Processes for the production of filter elements based on aromatic polyamide in which a semi-finished filter element is produced from a solution of the polyamide in aprotic solvent and the polyamide is then coagulated by immersion in a liquid bath containing precipitating agent may be used for the production of filter elements with a pore size of from 0.05 .mu.m to 10 .mu.

Abstract: A stable tetravalent nickel oxide cathode, having a high coulombic capaci for use in high energy density batteries comprising a nickel hydroxide plate prepared by impregnating a porous conducting plaque with nickel hydroxide which is then further wet oxidized by passing a stream of ozone through the plate. The ozonation process further comprises impregnation of the nickel hydroxide plate with an alkaline solution such as an aqueous solution of potassium hydroxide and flowing of a stream of gaseous ozone through the plate by producing a pressure differential across the plate while applying water or potassium hydroxide solution to the plate to facilitate the action of the ozone on the nickel hydroxide-potassium hydroxide mixture. The tetravalent nickel oxide thus formed has the stable gamma structure with a valence approaching +4.0.

Abstract: The present invention provides for an absorbent planar structure or so-called "sponge cloth" as well as for the method of making such a structure. The absorbent planar structure itself is permeated with pores and comprises a latex-bonded fiber material optionally reinforced with a woven or knit material, a layer of known foamed plastic, non-woven fabric or abrasive fleece. The method for making such a structure dispenses with conventional pore formers and is characterized by forming a foam of the latex and fiber materials by use of a suitable gaseous medium. The foam thus obtained, after homogeneous mixing, is applied to a substrate and the fiber-containing latex foam is then coagulated by heat action, resulting in an open-pore structure which is stabilized by subsequent drying and vulcanization.

Abstract: The invention relates to a waterproof and air-tight, moisture-conducting textile material (1) which has a coating (3) of coagulated polyurethane containing preferably a great number of micropores, and which has a water vapor permeability of more than 5000 g/m.sup.2 in 24 hours.

Abstract: A nickel oxide electrode is made by impregnating a porous nickel substrate with a dispersion of a nickel compound, converting the compound in situ to nickel hydroxide, and removing reaction products.In order to overcome corrosion problems, facilitate removal of by-products and improve electrode performance, the dispersion is provided in a non-aqueous medium (e.g. as a methanolic solution of NiCl.sub.2.6H.sub.2 O) such that the in situ conversion gives rise to the nickel hydroxide in the form of a gel and to easily removable (e.g. volatile) reaction products. Such a conversion may be carried out by contacting the methanolic solution with an epoxy compound such as propylene oxide.

Abstract: A moisture-permeable waterproof coated fabric having a microporous polyurethane layer is obtained by the so-called wet coagulation method using as a coated solution a polar organic solvent solution containing 8 to 25% by weight of a polyurethane elastomer, 0.1 to 10% by weight of a water repellent agent, 0.2 to 3% by weight of polyisocyanate and 1 to 8% by weight of a nonionic surfactant.

Abstract: In the formation of polymeric layers, especially anisotropic polymeric layers, on a solid substrate on which the layer is formed by cross-linking of an organic substance which can be cross-linked, the cross-linking is performed in a manner such that a concentration gradient of at least one of the components controlling the cross-linking reaction is formed in the boundary layer between the substrate to be coated and the surrounding solution, which concentration gradient is adjusted so that cross-linking can take place in the boundary layer but not in the surrounding solution. The concentration gradient is preferably achieved by impregnating the substrate with at least one of the components which control the cross-linking reaction and which tends to diffuse into the solution on contact therewith.

Abstract: A method of upgrading the .[.selectively.]. .Iadd.selectivity .Iaddend.of a dry asymmetric permselective membrane comprising a porous barrier layer adjacent to a porous main body, where the barrier layer has an external .[.obverse.]. surface .Iadd.and the main body has an external obverse surface.Iaddend.. The method comprises maintaining the barrier layer surface in a drying atmosphere while applying a wetting liquid which is not a solvent for the bulk of the membrane to the obverse surface to wet interstices of the bulk of the membrane, and drying the membrane by continuing the exposure of the external surface of the barrier layer to the drying atmosphere as the wetting liquid moves from the obverse surface through the membrane main body and the barrier layer.