EP0750531A1 - Procede de formation de revetements minces durables constitues de polymeres contenant des ions sur des substrats selectionnes - Google Patents

Procede de formation de revetements minces durables constitues de polymeres contenant des ions sur des substrats selectionnes

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Publication number
EP0750531A1
EP0750531A1 EP95913739A EP95913739A EP0750531A1 EP 0750531 A1 EP0750531 A1 EP 0750531A1 EP 95913739 A EP95913739 A EP 95913739A EP 95913739 A EP95913739 A EP 95913739A EP 0750531 A1 EP0750531 A1 EP 0750531A1
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EP
European Patent Office
Prior art keywords
substrate
ionomer
solution
dispersion
coating
Prior art date
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Ceased
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EP95913739A
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German (de)
English (en)
Inventor
Charles W. Martin
Terry D. Gordon
Stan H. Baker
Melisa Davila
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Dow Chemical Co
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Dow Chemical Co
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Application filed by Dow Chemical Co filed Critical Dow Chemical Co
Publication of EP0750531A1 publication Critical patent/EP0750531A1/fr
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/10—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by other chemical means
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D1/00—Processes for applying liquids or other fluent materials
    • B05D1/18—Processes for applying liquids or other fluent materials performed by dipping
    • B05D1/185—Processes for applying liquids or other fluent materials performed by dipping applying monomolecular layers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
    • B05D3/00—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials
    • B05D3/10—Pretreatment of surfaces to which liquids or other fluent materials are to be applied; After-treatment of applied coatings, e.g. intermediate treating of an applied coating preparatory to subsequent applications of liquids or other fluent materials by other chemical means
    • B05D3/107—Post-treatment of applied coatings
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
    • B82Y40/00—Manufacture or treatment of nanostructures
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    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/244—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing sulfur or phosphorus
    • D06M13/248—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing sulfur or phosphorus with compounds containing sulfur
    • D06M13/256—Sulfonated compounds esters thereof, e.g. sultones
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    • D06M13/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment
    • D06M13/244—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing sulfur or phosphorus
    • D06M13/248—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing sulfur or phosphorus with compounds containing sulfur
    • D06M13/265—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with non-macromolecular organic compounds; Such treatment combined with mechanical treatment with compounds containing sulfur or phosphorus with compounds containing sulfur containing halogen atoms
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    • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/195—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds sulfated or sulfonated
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    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/21—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M15/227—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of hydrocarbons, or reaction products thereof, e.g. afterhalogenated or sulfochlorinated
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    • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/21—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M15/227—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of hydrocarbons, or reaction products thereof, e.g. afterhalogenated or sulfochlorinated
    • D06M15/233—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of hydrocarbons, or reaction products thereof, e.g. afterhalogenated or sulfochlorinated aromatic, e.g. styrene
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    • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/21—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M15/244—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of halogenated hydrocarbons
    • D06M15/256—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of halogenated hydrocarbons containing fluorine
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    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/21—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M15/263—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of unsaturated carboxylic acids; Salts or esters thereof
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    • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/21—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M15/347—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of unsaturated ethers, acetals, hemiacetals, ketones or aldehydes
    • D06M15/353—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of unsaturated ethers, acetals, hemiacetals, ketones or aldehydes containing fluorine
    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M15/00—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment
    • D06M15/19—Treating fibres, threads, yarns, fabrics, or fibrous goods made from such materials, with macromolecular compounds; Such treatment combined with mechanical treatment with synthetic macromolecular compounds
    • D06M15/21—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
    • D06M15/356—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of other unsaturated compounds containing nitrogen, sulfur, silicon or phosphorus atoms
    • D06M15/3566—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds of other unsaturated compounds containing nitrogen, sulfur, silicon or phosphorus atoms containing sulfur

Definitions

  • the present invention relates to processes for forming thin coatings of ion- containing polymers on selected substrates, and to the articles made thereby. More particularly, but without limitation, this invention relates to processes for forming coatings of such polymers on such substrates, using a surface active dispersion of an ion-containing polymer which will wet the particular substrate to be coated.
  • Examples of the known ion-containing polymers include the sulfonated o polystyrenes, copolymers of ethylene with alpha-beta unsaturated carboxylic acids such as acrylic acid or methacrylic acid and perfluorocarbon ionomers.
  • the perfluorocarbon ionomers include those with sulfur-based functional groups, phosphorus-based functional groups and carboxylic acid or carboxyiate functionality. All of these materials, with the exception of the phosphorus-based perfluorocarbon ionomers, are presently commercially-available.
  • Dispersions of copolymers of a non-acid, ethylenically unsaturated monomer with an ethylenically unsaturated carboxylic monomer are well known in the art, and are described 5 for example in United States Patents 3,799,901 and 5,206,279, and in the references summarized therein.
  • Ethyl ene-acrylic acid copolymers in particular are commercially available from The Dow Chemical Company under the mark PrimacorTM, which contain from 3 to 20 weight percent of the acrylic acid monomer.
  • Dispersions of ethylene acrylic acid copolymers are available from Morton International under the mark AdcoteTM, but can also be prepared by stirring a high acid polymer (typically 20 percent by weight of acrylic acid monomer) with a solution of aqueous ammonium hydroxide at from 95 to 110 degrees Celsius for from 30 to 90 minutes in a closed vessel. Typically, 0.8 moles of ammonium hydroxide is used per mole of acrylic acid to make a dispersion containing 25 percent by weight of ethylene acrylic acid copolymer.
  • a surface active dispersion can be prepared therefrom for coating polytetrafluoroethylene, polyethylene or polypropylene, for example, by diluting 4 parts by weight of the 25 weight percent aqueous dispersion with 96 parts by weight of an equal mixture by weight of water and ethanol.
  • a partially sulfonated polystyrene (orSPS) can be prepared for example by the procedure outlined in United States Patent No. 3,072,618. An SPS polymer prepared in this fashion and containing 1.2 meq/g of dry polymer will dissolve in 1,4-dioxane.
  • a surface active solution or dispersion of the partially sulfonated polystyrene polymer can thereafter be prepared which by visual inspection provides a good coating on substrates like polytetrafluoroethylene, polyethylene and polypropylene, by diluting a 2 percent by weight solution of the polymer in 1 ,4-dioxane with an equal volume of deionized water.
  • Dispersions of the perfluorosulfonic acid ionomers and of the perfluorosulfonate ionomers have been made previously by processes as described for example in United States Patent No.4,731 ,263 to Martin et al. (salt form placed in solution or dispersion at 250 deg. Celsius and elevated pressures, then solvent removed at low temperature and resulting solids able to be redispersed at room temperature in a variety of solvents), United States Patent No. 4,661,411 to Martin et al.
  • Dispersions of the NafionTM ionomers are also available commercially in various equivalent weights which employ a lower alcohol/water combination as the liquid medium or solvent. Thin films have previously been formed using these perfluorocarbon ionomer dispersions by evaporative coating techniques on various substrates, as best seen for example in the aforementioned Martin and Grot patents (suitable substrates being catalyst supports such as alumina, silica, zeolites, carbon etc., perhalocarbon- or glass-containing fabrics, ion exchange membranes or porous diaphragms, and wire or wire mesh electrodes), in United States Patents No.4,680,101 to Darlington et al. and 4,720,334 to DuBoisetal.
  • the present invention concerns novel and improved processes for forming thin coatings of ion-containing polymers and especially of the perfluorosulfonate salt form ionomers on selected substrates, which comprise contacting the substrate with a colloidal, surface active dispersion of an ion-containing polymer and then contacting the dispersion- wetted substrate (whilestill wetted with the colloidal dispersion or solution) with a solution of a salt or of a strongly ionizing acid which is of a sufficient concentration to cause an adherent coating (which may be continuous but is not necessarily so) of the ion-containing polymer to be formed on the surface of the substrate.
  • This coating is typically on the order of less than 100 nanometers thick, and desirably is on the order of 5 to 10 nanometers thick.
  • An optional additional step may involve exchanging the cation of the ionomer after this initial salt or acid solution-contacting step, as by contacting the dispersion-wetted substrate with the same or a different salt solution, for example with a potassium salt solution rather than a sodium salt solution, where the newly-exchanged form of the ionomer is less effective than the original form in coating the substrate initially but is more amenable to a particular end use or to further processing, or possesses a quality or property more fully than the original salt or acid form.
  • a further optional step may include treatment of the coated substrate at an elevated temperature to provide improved coating adhesion to the substrate or for other purposes, as will be described below.
  • those amphipatic, ion-containing polymers which may be placed in surface active dispersions generally are of interest, and the ion-containing polymers with low ionic functionality (for example, containing less than 20 mole percent of the ionizable monomer) are particularly of interest for forming essentially continuous coatings on a variety of substrates.
  • Ion-containing polymers which when formed into a dispersion or solution do not wet out a given substrate to this extent, that is, which do not provide a contact angle with the dispersion- or solution-wetted substrate approaching zero, are also useful but are much less preferred.
  • the acid solutions which can be used to subsequently contact a dispersion- or solution-wetted substrate according to the inventive processes include aqueous solutions of those acids which are conventionally known or classified in the art as "strong" acids, for example, nitric acid, hydrochloric acid or sulfuric acid.
  • strong acids for example, nitric acid, hydrochloric acid or sulfuric acid.
  • a salt solution will be employed.
  • the optimum salt concentration in the salt solution employed in a given embodiment depends on the salt being used, but typically is in excess of about 1 percent by weight of the salt solution and preferably is between about 5 percent by weight of the solution and saturation in the solution.
  • Salts which have been found suitable for use in the present invention include cations such as hydrogen, alkali metals, alkaline earth metals and transition metals, ammonium and alkylammonium cations in water-soluble combinations with any anion such as sulfate, fluoride, chloride, bromide, iodide, carbonate, phosphate, acetate, hydroxide, nitrate orthiocyanate.
  • cations such as hydrogen, alkali metals, alkaline earth metals and transition metals, ammonium and alkylammonium cations in water-soluble combinations with any anion such as sulfate, fluoride, chloride, bromide, iodide, carbonate, phosphate, acetate, hydroxide, nitrate orthiocyanate.
  • sodium chloride, sodium carbonate, sodium acetate and sodium bisulfate have all been found especially useful in forming essentially continuous coatings on substrates such as PTFE, although as suggested above, it may be desirable after forming the coating initially to exchange a different cation for the sodium in the ionomer through contacting the sodium-exchanged, perfluorosulfonate ionomer coating with a solution of the cation. Particular examples of instances wherein it would be advantageous to perform this additional step will be given hereafter.
  • the durability and strength of adhesion of the ionomer coating are enhanced in preferred embodiments of the invention by annealing at an elevated temperature.
  • the optimum annealing temperature to be employed in any given application will depend on the structure of the ionomer, the counter ion and the thermal properties of the substrate. In general, however, the greatest improvement in adhesion to a polymeric substrate is realized by annealing the coating at a temperature which is nearthe ionic glass transition temperature (T g ) of the ionomer in question or nearthe T g or crystalline melt point of the polymeric substrate, but below the decomposition temperatures of the ionomer and substrate.
  • T g ionic glass transition temperature
  • the processes of the present invention can be adapted to provide a plurality of such coatings on a selected substrate by contacting the coated substrate with a second, salt solution involving a different cation to increase the contact angle of the coated substrate prior to applying an additional coating of ionomer (in the manner used in applying the initial coating, namely contacting with the dispersion and then with the first, original salt solution), and by heat treati ng the coated substrate to further raise the contact angle.
  • the heat treatment step alone may suffice to raise the contact angle of the substrate to an extent such that an additional coating may be applied.
  • This heat treatment will generally be conducted at a temperature lower than that recommended for the annealing, adhesion-enhancing step, and preferably following deposition of the final coating the annealing step will be performed.
  • the ionomers which will be preferred for use in coating a particular substrate will depend on the context of the coated article's application and use.
  • the perfluorocarbon ionomers are generally to be preferred, whereas in other applications and uses not requiring the chemical and thermal stability of these materials the sulfonated polystyrenes and ethylene- acrylic acid copolymers are generally to be preferred by virtue of their lower cost.
  • preferred embodiments of the coating processes and coated articles of the present invention will be based on colloidal, surface active dispersions of a perfluorosulfonic acid ionomer or perfluorosulfonate ionomer.
  • Ionomers which are of the type sold by E.I. DuPont de Nemours & Co., Inc. under the NafionTM mark are suitable, as are the shorter side chain sulfur-based ionomers sold by The Dow Chemical Company and described by structural formula above.
  • the Dow Chemical Company's shorter side chain ionomers are presently more preferred where maximum ionic content and surface wettability are desired, and more generally are preferred fortheir adaptability to a novel, solventless (organic) perfluorocarbon ionomer coating process which is described more particularly below.
  • Dispersions are commercially available or have been made previously using perfluorosulfonic acid or perfluorosulfonate ionomers of various equivalentweights, but preferably the perfluorinated ionomers employed herein will possess equivalentweights in the range of 500 to 1500, and most preferably will possess equivalentweights in the range of from 550 to 1200.
  • any known method for making colloidal dispersions of ionomers having these equivalentweights may suitably be employed, for example, dissolving solid ionomer in a mixture of water and a lower alcohol (for example, ethanol or propanol) at elevated temperatures and pressures in a closed vessel (such method being described in the aforementioned United States Patent No.4,433,082 to Grot).
  • a lower alcohol for example, ethanol or propanol
  • Commercially-available dispersions may also be used of NafionTM ionomer in a lower alcohol/water solvent system at these equivalent weights.
  • dispersions will be prepared from at least certain of these ionomers for coating a selected substrate which employ water only as the solvent.
  • a completely water-based dispersion is preferable in that the flammability, inhalation and emission/environmental concerns associated with an ethanol/water solvent system, for example, are not present with water as the solvent for these dispersions.
  • the shorter side chain ionomers produced by The Dow Chemical Company are especially preferred for use in the context of a solventless coating process, as has been mentioned previously, because they have proven amenable at equivalent weights of from 550 to 1000, and especially at equivalent weights of from 550 to 800, to being dispersed in water alone in high yields (where the yield is defined as the amount of ionomer solids which are effectively dispersed into the liquid solvent divided by the total amount of ionomer solids attempted to be dispersed) and under moderate conditions.
  • the '082 patent to Grot does contemplate the possibility of making dispersions of up to 10 percent by weight of perfluorosulfonic acid form ionomers in water alone (the ionomers having equivalentweights in the range of 1025 to 1500), at temperatures of at least 240 degrees Celsius in a closed vessel with stirring.
  • the examples illustrating this process show pressures of upwards of 370 pounds per square inch (2.5 MPa), and yields in room temperature dispersions of about 27 percent (after 100 hours agitation at 240 degrees and 370 psi) and of 48 percent (after 18 hours at 235 degrees Celsius).
  • room temperature dispersions containing from 1 to 3 weight percent of the aforementioned lower equivalent weight, acid form shorter side chain ionomers can be prepared in the context of a solventless (organic) coating process of the present invention with stirring in a closed vessel at temperatures of from 170 to 200 degrees Celsius, a pressure of from 110 pounds per square inch, absolute (psia) (0.76 MPa, absolute) to 225 psia (1.6 MPa, absolute), and over a time frame of from 1 to 3 hours with yields on the order of from 70 percent to 95 percent or greater being demonstrated for an 800 equivalent weight ionomer.
  • a powdered ionomer in the desired equivalent weight is combined with water in a dosed vessel, and heated to a temperature of from 180 to 185 degrees Celsius with stirring for about 2 hours, with the pressure being on the order of 145 to 165 psia (1.0 MPa, absolute to 1.1 MPa, absolute).
  • the substrates which may be coated with ionomers according to the process of the present invention are numerous, and may desirably include for example fibers, powders, fabrics, articles or items of polytetrafluoroethylene, polyvinylidene fluoride, fluorinated ethylene-propylene copolymers (FEP), poly(vinyl chloride), glass, polypropylene, carbon, steel, platinum, chlorotrifiuoroethylene or perfluoroalkoxyvinyl ether-tetrafluoroethylene copolymers (such as are sold under the designation Teflon PFATM by E.I. DuPont de Nemours & Co., Inc.).
  • FEP fluorinated ethylene-propylene copolymers
  • the present invention is concerned with coatings, articles which comprise an outer layer or coating of any of the aforementioned substrate materials may also suitably be coated with an ionomer dispersion according to the present invention.
  • the process of the present invention can be used to provide an ionomeric coating as a transition surface between any two materials whose surfaces form (in the absence of the ionomeric coating) a high surface energy interface.
  • Such an interface would be the interface between a f luoropolymer matrix material and reinforcing filler materials such as carbon, ceramics or glass that are often used in PTFE to reduce cold creep, lower the coefficient of thermal expansion and improve compressive strength over an unfilled PTFE in the context of PTFE bushings, bearings and low dielectric circuit boards, for example.
  • the present ionomer coating process offers a simple alternative to corona discharge or corrosive chemical treatments with, for example, sodium amide or sodium naphthide that are often used to make fiuoropolymer surfaces more wettabie and thus more bondable.
  • the catalytic sites must be accessible to the reacting gases and to a proton conductor.
  • a thin (for example, less than a micrometer in thickness) coating of a perfluorocarbon ionomer on a catalyst (supported or unsupported) would provide a proton conductor without impeding gas diffusion to the catalyst-ionomer interface.
  • the perfluorocarbon ionomer coating enabled by the present invention could also be used in the preparation of electrolytic capacitors such as those described in United States Patent No. 5, 136,474 to Sarangapani etal to provide maximum proton conductivity and maximum interfacial area.
  • a particularly preferred application of the present invention is for placing an ionomeric coating or plurality of such coatings, and especially a perfluorocarbon ionomer coating or coatings, on polytetrafluoroethylene (PTFE) fibers and/or powders to make the PTFE f i bers and/or powders water-
  • PTFE polytetrafluoroethylene
  • PTFE possesses a number of desirable attributes, including excellent chemical stability.
  • a significant barrier has existed however to the use of PTFE in certain applications, for example in the development of nonasbestos diaphragms for chlor- -alkali cells, due to the hydrophobic nature of PTFE.
  • Various efforts have been made to compensate for or to overcome the hydrophobic character of PTFE in chlor-alkali diaphragms through the incorporation of ion- exchange materials. An example of these efforts may be found in United States Patent No.
  • PTFE or a similar fiuoropolymer in the form of a powder or fibers, in an unsupported porous or nonporous film, in a coating on an inert fabric or in a porous reinforced structure (that is, a diaphragm) is chemically modified by reaction with a sulfur- or phosphorus-containing compound.
  • United States Patent No.4,720,334 to DuBois et al. is also representative, and describes diaphragms containing from 65 to 99 percent by weight of a fibrillated fluorocarbon polymer such as PTFE and from 1 to 35 percent of fiuorocarbon ionomer (preferably containing carboxylic acid, sulfonic acid, alkali metal carboxylate or alkali metal sulfonate functionality) based on the combined weight of fibrillated fiuoropolymer and ionomer, and optionally further containing wettabie inorganic particulate material.
  • a fibrillated fluorocarbon polymer such as PTFE
  • fiuorocarbon ionomer preferably containing carboxylic acid, sulfonic acid, alkali metal carboxylate or alkali metal sulfonate functionality
  • the diaphragm is dried and secured upon an underlying cathode by being heated to a temperature below the sintering temperature of PTFE for a time.
  • the ionomer can be incorporated in the diaphragm by codeposition from a slurry with the ionomer being included as a solid, gel or solution, by being coated on either or both of the fiuorocarbon fibrils and inorganic particulate and then deposited from a slurry, or by being extruded in admixture with the fiuoropolymer before it is fibrillated.
  • Specific coating processes for coating the PTFE fibrils including mixing PTFE powder with a solution of ionomer in a water-miscible solvent under high shear conditions, then dispersing the coated fibrils by blending with water and some surfactant. Thereafter the materials are deposited onto the cathode from the resulting slurry.
  • PTFE powders or fibers are initially mixed with a colloidal dispersion of a perfluorosulfonate ionomer which preferably is produced from the short side chain, acid form ionomer produced by The Dow Chemical Company and described above, and which has an equivalent weight of from 550 to 1200.
  • a perfluorosulfonate ionomer which preferably is produced from the short side chain, acid form ionomer produced by The Dow Chemical Company and described above, and which has an equivalent weight of from 550 to 1200.
  • This colloidal dispersion can be made, for example, by acid washing a film of the acid-
  • the reactor After sealing the liner in a stainless steel reactor, and purging with nitrogen, the reactor is stirred and heated to a temperature at least on the order of 160 degrees to 180 degrees Celsius for from 1 to 3 hours, producing a pressure in a 1 liter reactor of 180to 220 psig (1 -2 MPa, gauge to 1.5 MPa, gauge). The reactor is then allowed to cool, the excess pressure bled off and the contents filtered through a 60 to 80 micron fritted glass filter. The resulting concentrated dispersion is then diluted with the ethanol/water mixture to finally provide the desired and preferred dispersion containing 1 percent by weight of the perfluorosulfonate ionomer.
  • perfluorosulfonyl polymers in powder form can be used instead of the aforementioned ionomer film, and the powders hydrolyzed in sodium hydroxide and dissolved and processed as described above.
  • Other known methods of making a dispersion of the perfluorosulfonate ionomer can be used without limitation as well.
  • Contacting a powdered PTFE substrate with the alcohol/water based dispersion made by this process preferably involves mixing the dispersion and PTFE powder in a 0.015 to 1 ratio by weight of ionomer solids to PTFE, on a dry basis. This ratio can be adjusted appropriately to achieve a doughy, handleable mass.
  • these substrates may be sprayed with or dipped into the ionomer dispersion and the excess allowed to drain before contacting with a salt solution.
  • the liquid coated substrate is then stirred directly and without drying into the salt solution (in the case of coated PTFE powders or fibers) or immersed (for coupons or the like) directly in the salt solution.
  • Suitable salt solutions are (for the coating of PTFE materials to make them water- wettable with the alcohol/water-based dispersions or the ionomer dispersions in water alone) formed from water and from the water-soluble salts of the alkali, alkaline earth or transition metals, strong acids, and the ammonium salts of ammonia, the primary, secondary, tertiary or quaternary amines.
  • Preferred salt solutions are prepared from the water-soluble sodium and magnesium salts for forming an initial coating on PTFE, and of these (as has been previously indicated) sodium chloride, sodium acetate, sodium carbonate and sodium bisulfate are particularly preferred.
  • the coated PTFE For purposes of achieving maximum water-wettabiiity or for adding subsequent coatings, it will be preferred to then contact the coated PTFE with a potassium or zinc salt solution, and for adding subsequent coatings to also heat treat at an elevated temperature, for example, up to 300 degrees Celsius for 20 to 30 minutes. Then the single- coated substrate is contacted with the dispersion, exposed to the sodium or magnesium salt solution, rinsed, exposed to the potassium or zinc salt solution, rinsed, heat treated and so on until the last coating is applied that is desired, with the final heat treatment being an annealing of the coated substrate.
  • a potassium or zinc salt solution for adding subsequent coatings to also heat treat at an elevated temperature, for example, up to 300 degrees Celsius for 20 to 30 minutes.
  • the quality of an ionomer coating produced according to the present invention is ultimately affected by the ionomer concentration in the colloidal dispersion, by the dispersion's solvent composition, and by the temperature, salt concentration and pH of the salt solution.
  • Each of these variables interact with each other and with the salt type and the ionomer structure. It is expected however that those skilled in the art will be able to determine the optimum combination of these variables for a given application (including the coating of substrates other than PTFE and/or for purposes other than imparting water-wettability thereto) by following the approach of the illustrative Examples provided below.
  • this ionomer dispersion should contain 1.6 percent by weight of ionomer in a mixture of 63 percent by volume of ethanol in water, and the salt solution should be a 25 percent by weight solution of sodium chloride in water at a temperature of 65 degrees Celsius.
  • a solventless (that is, employing only water as the liquid medium of the dispersion) coating process of the present invention is preferred, and can be carried out in several ways depending on the ionomer type employed and the nature of the dispersion to be used.
  • an integrated coating process would initially and preferably involve the preparation of a dispersion in water of from 1 to 3 percent by weight of a perfluorosulfonic acid form ionomer having an equivalent weight of from 550 to 1000, and especially from 550 to 800 inclusive, by the procedure described above.
  • an available alcohol/water-based dispersion could be conventionally processed to remove the alcohol.
  • a dispersion could be prepared in water of up to 10 percent of an ionomer of an equi alent weight of from 550 to 1500, according to the process and under the conditions specified in U.S. Pat. No.4,433,082 to Grot, or more commonly a commercially-available aicohol/water-based dispersion will again be conventionally processed to remove the alcohol.
  • the resulting dispersion is then added to a PTFE powder, for example, which will preferably have been subjected to intensive shearing in waterto produce uniformly-sized PTFE particles, or to preferably presheared PTFE fibers, orto a mixture of PTFE in powder/granular form and in the form of fibers.
  • the mixture is then subjected to high shear conditions generally corresponding to a blade tip speed on the mixer used of 800 ft./minute (240 meters/minute) or greater, for a time sufficient to coat the PTFE substrate with the ionomer and achieve a uniform slurry, with care being taken to not create such heat by excessive mixing/shearing as might cause the coated PTFE to begin to clump together.
  • the liquids in question are to be added to the PTFE, as opposed to the PTFE being added to the water or dispersion.
  • the resulting ionomer to PTFE solids ratio will generally be 0.005 to 1 by weight or greater, preferably being from 0.005 to 1 to 0.015 to 1 and most preferably being approximately 0.015 to 1 , with sufficient ionomer and PTFE being present for a given volume of waterto achieve adequate shearing of the solids and coating of the PTFE by the ionomer.
  • This minimum solids level can reasonably be expected to vary with different tip speeds and different mixing conditions and with different equipment, but can be determined through routine experimentation.
  • the ionomer coated PTFE may thereafter be contacted in situ with the requisite salt solution, in the draw vat for drawing a nonasbestos diaphragm.
  • the coated PTFE may be removed from a salt solution, rinsed with waterto remove excess salt and air-dried.
  • the coated PTFE for such other applications and uses is kept wetted afterthe optional rinse step, in that coated PTFE which has been dried generally requires vigorous agitation or stirring to be rewetted.
  • Both of the above-described coating processes (that is, involving coating from a dispersion of ionomer in an organic solvent (commonly a lower alcohol) and water, and from an ionomeric dispersion prepared in water only or from which the organic solvent has been removed) produce an evenly thin ionomeric coating which is sufficiently durable to be rinsed in water without being substantially removed, but which can be removed with mechanical abrasion.
  • the durability and strength of adhesion of the ionomer coating can be enhanced (to the point where the coating may not be removed with hand rubbing) where desired for a given use or application, by annealing the coated substrate at an elevated temperature below the decomposition temperature of the ionomer coating.
  • the optimum annealing temperature in a given application is, again, generally dependent on both the structure and salt form of the ionomer and on the nature of the substrate. Adhesion of the coating to the substrate is generally improved by annealing near or above the glass transition temperature of the ionomer. More preferably, for achieving the greatest adhesion and durability with the ionomer coating of a polymeric substrate, the annealing will occur near the glass transition temperature (T g ) of an amorphous polymeric substrate or nearthe crystalline melting point of a crystalline polymeric substrate.
  • the greatest degree of adhesion and durability is generally achieved with an annealing of the coated PTFE at a temperature of from 330 to 350 degrees Celsius for from one to 360 minutes, while for polyvinylidene fluoride substrates coated with the same ionomer, the preferred annealing conditions correspond to a temperature of from 160 to 170 degrees Celsius maintained for from one to 360 minutes.
  • the benefits of enhanced adhesion may be offset to an extent in that with the re-orienting of the substrate surface under these conditions, some migration of the ionomer into the substrate can be expected with an attendant loss of some wettability, for example, in the sintering of a chlor-alkali diaphragm including ionomer- coated PTFE. Consequently, the adhesion and durability that can be achieved under selected annealing conditions for a given end use or application should be weighed against the effect of a decrease in wettability or some other property which may result, to determine whether it is desirable to achieve such enhanced adhesion and durability forthe end use or application.
  • ionomers may be useful or desirable (having different backbone structures, different functionalities or being in different salt forms), ionomers of different equivalent weights may be useful or preferable, salt solutions for example of different compositions, temperatures and/or pH's may be useful or preferred, and annealing may not be appropriate or may appropriately involve different temperatures.
  • the film which contained 1.25 milliequivalents of sulfonic groups per gram of dry weight was cut into small pieces and 5 parts byweight (on a dry basis) of these film pieces were placed in a stirred pressure vessel with 95 parts by weight of a mixture of equal parts by volume of ethanol and water. The vessel was then heated with stirring to 165 degrees Celsius for 4 hours. After cooling, the percent solids of the resulting dispersion was determined to be 5.1 wt. percent by evaporating a weighed sample to dryness and weighing the residue. The colloidal dispersion was colorless with a slight haze.
  • This dispersion was used to coat TeflonTM 7C PTFE powder, a strip of PTFE film, a polypropylene coupon and a steel coupon.
  • 100 grams of the powder were placed in a beaker and 700 grams of the dispersion added thereto.
  • the mixture was agitated with a Lightning DS1010TM stirrer at 600 rpm for about 20 minutes until a uniform slurry was obtained.
  • This slurry was vacuum filtered using a medium to coarse filter paper, and the wet cake placed in a solution of 5 weight percent of sodium carbonate in water at room temperature and al lowed to stand for 15 minutes.
  • the treated powder was then redispersed with the stirrer, and recovered by vacuum filtration.
  • the filter cake was washed to neutrality by three iterations of dispersing the wet cake in deionized water with agitation in a high shear blender and recovering by vacuum filtration.
  • the powder remained easily wettabie throughout and would sink to the bottom of the blender when agitation was stopped, and was observed to rewet after drying by stirring with deionized water.
  • a sample of the powder was treated with the ionomer dispersion, filtered and placed in a blender with deionized water. After blending for 2 minutes, the powder was observed to lose its wettability and coat the walls of the blender and to float on the surface of the water.
  • a 1/2 inch (1.3 cm.) wide by three inches (7.5 cm.) long strip of PTFE film was cleaned with acetone and deionized water, immersed for most of its length in the ionomer dispersion for about 10 seconds, removed and allowed to drain briefly, then immersed in a 5 weight percent solution of sodium carbonate in water at room temperature for about 10 seconds.
  • the film was then washed with flowing deionized water to remove any loose material and excess salt, and treated with an aqueous solution of Safranine 0TM cationic dye dispensed with an eye dropper.
  • the ionomertreated area remained wetted throughout all of these steps and absorbed the dye, to leave a uniform reddish pink coloration which was not removed by rinsing with deionized water but which could be removed with adhesive tape or by rubbing.
  • a coated PTFE film that was not immersed in the sodium carbonate solution dewetted and would not hold the dye.
  • the polypropylene coupon when coated with the dispersion and immersed in a 26 wt. percent solution of sodium chloride and water at room temperature provided a wettabie, uniformly dyed surface by the same procedures, as did the degreased steel coupon which was coated and immersed in the same 26 wt. percent sodium chloride solution.
  • Example 5 A PTFE film was coated with the ionomer dispersion of Examples 1-4, immersed in a 5 weight percent solution of sodium carbonate in water at room temperature and the film rinsed to remove loose materials and excess salt, but the film was not treated with the dye. The film was then annealed by heating slowly from room temperature to 350 degrees Celsius (for example, at about 20 degrees per minute) in a Hewlett-Packard 5880 gas chromatograph oven, and being held at this temperature for 1/2 hour before cooling to room temperature (typically over a span of from 10 minutes up to 2 hours).
  • the film After being cooled to room temperature, the film was treated with the Safranine OTM dye solution.
  • the coated part of the film absorbed the dye and acquired a reddish-pink coloration which was not removed by adhesive tape or by rubbing.
  • the heat treated or annealed film (and more specifically the coated portion thereof) was observed to have a contact angle with water of about 100 degrees after cooling in air, of about 88 degrees after soaking in deionized water for 2 hours and of about 79 degrees after being immersed in deionized water for 20 hours at 70 degrees Celsius.
  • An uncoated film that had gone through the same heat cycle was observed to have a contact angle with water of about 126 degrees on cooling, and this contact angle was essentially unchanged after soaking in water for 2 hours.
  • the method used for making these contact angle measurements involved equilibration of the particular annealed, coated PTFE coupon in water at ambient temperatures, generally over a period of 16 hours or so. o Unannealed samples were rinsed after coating and left immersed in water until the contact angle was determined.
  • a given coated and salt solution-immersed PTFE coupon (annealed or unannealed) was thereafter removed from its deionized water soak and patted dry, then placed on the stage of a Kernco Contact Angle Meter, Model G-1 contact angle measuring 5 device; several measurements (10 to 14 measurements) were taken of the contact angle with water of the coated coupon on this device. Where the coupon in question would not lie flat on the device, 1/4 inch (0.6 cm.) diameter disks were cut therefrom using a hole punch and the contact angles determined on the sides of the disks which had not been exposed to the punch. Two measurements were made using the opposite edges of each disk, and the measurements 0 averaged as with the coupons. Examples 6-20
  • PTFE coupons to be coated were initially washed in acetone, rinsed with deionized water and dried. Thereafter the coupons were immersed in the ionomer solution, removed from the ionomer solution and allowed to drain for from 5 to 10 seconds, then immersed in the salt solution. The coupons were then removed and rinsed in deionized water. If a second coating 5 was to be applied, these steps were repeated without drying. The coupons were then air dried and annealed by heating to between 335 and 345 degrees Celsius and holding at this temperature for 30 minutes. After cooling, the coupons were soaked in deionized water overnight. The coupons were removed from the deionized water, patted dry and the contact angle with water determined in the manner described above.
  • Polytetrafluoroethylene coupons were coated in these examples with dispersions of the ionomer utilized in the preceding examples, at several different concentrations.
  • the coated coupons were then exposed to a basic 5 weight percent solution of sodium carbonate (Na 2 C0 3 ) in water at ambient temperature (25 deg. C).
  • the coupons were all then annealed as described previously.
  • the contact angles were then determined for specimens that had and that had not been equilibrated (soaked) prior to measurement of the contact angle by immersion in deionized water. The results from these tests are shown in Table 4:
  • Polytetrafluoroethylene coupons were coated with ionomer from dispersions having various solids concentrations as in previous examples, then immersed in one of several salt solutions at ambient temperature (25 deg. and a pH of 7 or 12.
  • the salt-form ionomers in these examples were exchanged with Ca + 2 , Mg + 2 , Zn + 2, K+ or Li +, with salt solutions being employed of the chloride salts of these cations or with a 26 weight percent sodium chloride salt solution being used, followed by conversion to the particular Ca + 2 , Mg + 2, Zn + 2, K + or Li + exchanged ionomers by soaking in 0.5 M solutions of the chloride salts of these cations for an hour.
  • the coatings produced on the slides in this fashion were then analyzed for smoothness and coating thickness by X-ray photon spectroscopy, with the smoothness being determined by scanning across the coating's surface while measuring the atom percent of fluorine in the coating.
  • the coating thickness was estimated by varying the angle of the X-ray photon spectroscopy beam while measuring the silicone signal observed through the coating.
  • the slides were removed from the dispersions and allowed to drain for 10 seconds, and then touched to clean glass slides to remove excess, last drops of dispersion therefrom.
  • the wetted slides were then placed back in the wide mouth jar, which was then capped.
  • the jar and coated slide contained therein were then reweighed for comparison to the observed precoated weight to determine the weight of the liquid film of the ionomer solution.
  • the potential coating thickness was calculated in each instance by assuming that all of the ionomer present in the liquid film was deposited as a uniform coating on the glass surface. This calculated thickness was compared to the measured thickness from the previous example.
  • Example 79 A small piece of platinum foil (1 cm. square in area) was picked up by one edge using forceps, and immersed to about 2/3 of its height in a dispersion (in 50 vol. percent ethanol/50 vol. percent water) of 1 wt. percent of the 800 equivalent weight perfluorinated sodium sulfonate form ionomer employed in earlier examples. The foil was then removed and allowed to drain for 10 seconds. The drop left at the bottom of the platinum square was removed by touching the foil square to the rim of the bottle containing the dispersion, and the wetted foil was then fully immersed in a solution of sodium bisulfate (20 wt. pet.) in water.
  • the foil was gently rinsed in a bottle of deionized water and then immersed in a dilute solution of Safranine OTM cationic dye.
  • the treated 2/3 of the foil absorbed the dye and remained rose- colored and wetted after further rinsing with deionized water.
  • the untreated (uncoated) 1/3 ofthe foil remained shiny and was water-beaded. Examples 80-89
  • Coupons of PTFE were soaked in 1,1,1-trichloroethane, then rinsed with acetone and deionized water. These were then immersed in the dispersion of Example 79, removed from the dispersion and allowed to drain momentarily, then immersed in a nitric acid solution or in one of the aqueous salt solutions listed below inTable 10. Afterbeing rinsed by agitating in a beaker of fresh deionized water, the surface wettability of the coupons was assessed visually. If water formed a continuous film on the coupon without beading, the coupon was deemed wettabie.
  • a 0.92 weight percent dispersion of an ethylene-acrylic acid copolymer (containing 20 percent by weight of acrylic acid) was prepared by diluting 1 part by weight of a commercially-available 25 percent by weight dispersion of such polymer (sold as Adcote 4983TM 5 EAA dispersion by Morton International Inc., containing 25 weight percent solids neutralized with 0.8 equivalents of ammonium hydroxide per equivalent of acid), with 12.8 parts by weight of water and 13.3 parts byweight of ethanol.
  • a PTFE coupon cleaned by acetone washing, deionized water rinsing and drying was immersed in part in the 0.92 per cent dispersion, the excess allowed to drain, the coated part immersed in a salt solution of 20 weight percent of sodium bisulfate in water and then water-rinsed.
  • the treated portion of the coupon was clearly water-wetted. After exposure to Safranine OTM dye, the treated portion showed a continuous area of very pale pink.
  • a clean PTFE coupon was immersed for comparison in a 1.0 weight percent solids dispersion in water alone (prepared by diluting 1.0 grams of the Adcote 4983TM material with 23.4 grams of deionized water), and drained of excess dispersion.
  • the surface of the coupon was not wetted by the dispersion except for a few isolated drops, and when immersed in the sodium bisulfate solution, rinsed with deionized water and immersed in diluted Safranine OTM in water displayed only a few isolated spots of pink corresponding generally to the earlier- noted drops of dispersion.
  • a sample of a sulfonated polystyrene (such as is commercially available from Aldrich Chemical Co., Inc.) containing 1 milliequivalentof acid groups per gram of polymer was dissolved in anhydrous dioxane to give a 1.1 weight percent solution of the sulfonated polystyrene.
  • An acetone-washed, water-rinsed and dried PTFE coupon was immersed in part in the sulfonated polystyrene solution and allowed to drain. A continuous film was not formed, and after immersion in a 20 wt. percent solution of sodium bisulfate in water and dyeing with Safranine OTM dye, only isolated areas of the coupon were observed to have been coated and dyed.
  • a second sulfonated polystyrene solution was then prepared containing 1.2 wt. percent of the sulfonated polystyrene in a mixture of 48 weight percent dioxane with 52 weight percent of water, with the sulfonated polystyrene first being dissolved in the dioxane and then diluting with water.
  • a cleaned PTFE coupon immersed in part in this solution showed a continuous film of the solution on the PTFE coupon surface.
  • the wetted coupon portion was immersed in the same sodium bisulfate salt solution, and after water-rinsing was water-wetted in a continuous film. After being dyed with Safranine OTM dye, a continuous rose-colored area was observed with some variation in the shade being seen as well.
  • a polypropylene coupon was coated by the same procedure, and yielded a translucent, continuous water-wetted area which was a deep rose color on dyeing with the Safranine OTM dye. Examples 94-100
  • the resulting polymer was isolated and dried, and hydrolyzed with NaOH to give a perfluorinated sodium sulfonate form ionomer. After being water-washed to neutrality, the ionomer was converted to the acid
  • Example 103 The same vessel, ionomer and procedurewere used as in Example 101, with 3 pounds (1.4 kg) of ionomer and 160 pounds (73 kg) of water being charged to the vessel. The temperature of this trial was 180 degrees Celsius, and the measured pressure reached 110 psig (0.8 MPa). The measured yield under these conditions was 98 percent.
  • Example 103 The same vessel, ionomer and procedurewere used as in Example 101, with 3 pounds (1.4 kg) of ionomer and 160 pounds (73 kg) of water being charged to the vessel. The temperature of this trial was 180 degrees Celsius, and the measured pressure reached 110 psig (0.8 MPa). The measured yield under these conditions was 98 percent.
  • Example 103 The same vessel, ionomer and procedurewere used as in Example 101, with 3 pounds (1.4 kg) of ionomer and 160 pounds (73 kg) of water being charged to the vessel. The temperature of this trial was 180 degrees Celsius, and the measured pressure reached 110 psig (0.8 MPa). The measured yield under these conditions
  • Example 104 For this example, 45 grams of an acid form, shorter side chain ionomer of the type used in Examples 94-100 above, but having an equivalent weight of 980, was placed in a vessel with 1400 grams of water. The vessel was closed, and the water/polymer mixture heated with stirring to 196 degrees Celsius and a pressure of 189 psig (1.3 MPa, gauge) for two hours. After cooling and evaporating a portion to dryness in the manner of Examples 94-100, the solids content of the dispersion was determined to be 2.82 percent by weight for a yield of from 94 to 95 percent (taking into account that the polymer when added to the vessel was not completely dried).

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Abstract

L'invention concerne des procédés d'application sans évaporation de polymères contenant des ions sur des substrats sélectionnés, et les produits ainsi obtenus. Ces procédés consistent principalement à mettre un substrat en contact avec une dispersion ou une solution de polymère contenant des ions et, plus particulièrement, une dispersion sans solvant d'ionomère d'acide perfluorosulfonique, à mettre ensuite le substrat imbibé de la dispersion ou de la solution en contact avec une solution de sel ou d'acide fortement ionisant en concentration suffisante pour entraîner la formation sur le substrat d'un revêtement adhésif constitué dudit polymère contenant des ions.
EP95913739A 1994-03-14 1995-03-14 Procede de formation de revetements minces durables constitues de polymeres contenant des ions sur des substrats selectionnes Ceased EP0750531A1 (fr)

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US5685755A (en) * 1995-09-07 1997-11-11 The Dow Chemical Company Non-asbestos diaphragm separator
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US5863610A (en) * 1995-12-20 1999-01-26 The Dow Chemical Company Process for depositing a fluorocarbonsulfonic ionomer on a support and articles prepared therewith
EP0932646B1 (fr) 1996-10-15 2001-07-25 E.I. Du Pont De Nemours And Company Compositions contenant des particules d'un polymere echangeur d'ions hautement fluore
US5928792A (en) * 1997-05-01 1999-07-27 Millipore Corporation Process for making surface modified porous membrane with perfluorocarbon copolymer
US6179132B1 (en) 1998-03-13 2001-01-30 Millipore Corporation Surface modified polymeric substrate and process
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CN103289574B (zh) * 2013-06-04 2015-11-25 苏州艾特斯环保材料有限公司 一种含有全氟磺酸树脂的防水耐热涂料
CN105080814B (zh) * 2014-04-22 2018-03-09 马德里高等材料研究院 逐层自组装聚电解质纳米阻燃涂层及其制备方法
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