EP0412916B1 - Diaphragm comprising asbestos fibres, association of such a diaphragm with a cathodic element and process of manufacture - Google Patents
Diaphragm comprising asbestos fibres, association of such a diaphragm with a cathodic element and process of manufacture Download PDFInfo
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- EP0412916B1 EP0412916B1 EP90420362A EP90420362A EP0412916B1 EP 0412916 B1 EP0412916 B1 EP 0412916B1 EP 90420362 A EP90420362 A EP 90420362A EP 90420362 A EP90420362 A EP 90420362A EP 0412916 B1 EP0412916 B1 EP 0412916B1
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- European Patent Office
- Prior art keywords
- fibres
- weight
- diaphragm
- coating
- binder
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Classifications
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B13/00—Diaphragms; Spacing elements
- C25B13/04—Diaphragms; Spacing elements characterised by the material
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B13/00—Diaphragms; Spacing elements
- C25B13/04—Diaphragms; Spacing elements characterised by the material
- C25B13/05—Diaphragms; Spacing elements characterised by the material based on inorganic materials
- C25B13/06—Diaphragms; Spacing elements characterised by the material based on inorganic materials based on asbestos
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B1/00—Electrolytic production of inorganic compounds or non-metals
- C25B1/01—Products
- C25B1/34—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis
- C25B1/46—Simultaneous production of alkali metal hydroxides and chlorine, oxyacids or salts of chlorine, e.g. by chlor-alkali electrolysis in diaphragm cells
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- C—CHEMISTRY; METALLURGY
- C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
- C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
- C25B13/00—Diaphragms; Spacing elements
- C25B13/02—Diaphragms; Spacing elements characterised by shape or form
Definitions
- the present invention relates to diaphragms comprising asbestos fibers for electrolytic cells, the association of such diaphragms with a cathode element and a method of obtaining such diaphragms and of association of such diaphragms with a cathode element.
- It relates more particularly to an improvement to diaphragms capable of being produced by the wet route, based on asbestos fibers, for chlor-soda electrolysis cells.
- Asbestos fibers have been used for a very long time as a conventional material for producing diaphragms used in electrolysis cells. These diaphragms are formed by depositing asbestos fibers contained in an aqueous slurry on an electrolyte-permeable cathode, the deposition operation being carried out under vacuum.
- French Patent No. 2,213,805 it has been proposed to prepare microporous separators by depositing a layer of asbestos, said layer being consolidated by a fluoropolymer. The porosity of such a layer can be better controlled by adding a blowing agent in accordance with the teaching of French Patent No. 2,229,739.
- cathode elements composite materials resulting from the association of an elementary cathode constituted by a highly porous metal surface such as a metal grid having a mesh void of between 20 ⁇ m, have been proposed. and 5 mm and of a sheet containing fibers and a binder, the association and the sheet resulting from the suction under programmed vacuum of a suspension, essentially containing electrically conductive fibers and a fluorinated polymer, directly to the through said elementary cathode, followed by drying, then melting of the binder.
- Such composite materials are capable of constituting the cathode itself of an electrolysis cell and can be associated with a diaphragm, the diaphragm being able to be manufactured directly by wet process on the composite.
- cathode elements which ensure an appreciable distribution of the current can be used in an electrolysis cell which will include a membrane or a diaphragm between the anode and cathode compartments. Additional technical details can be found in the aforementioned European patent applications, which are incorporated by reference to avoid further development on said cathode elements.
- microporous separators comprising improved asbestos, wet, by vacuum suction of an aqueous slurry containing fibers to through a porous support and to obtain a microporous separator which does not have the aforementioned drawbacks.
- the present invention also relates to the association of such a diaphragm and a composite cathode element.
- the diaphragms according to the present invention exhibit appreciable dimensional stability, fine and regular porosity and permanent wettability.
- the diaphragms according to the present invention also have very low operating voltages, which constitutes another advantage of the present invention.
- the diaphragms according to the present invention are capable of being obtained by means, conventionally used in industry, of deposits of a suspension by vacuum suction and allow the efficient operation (high current efficiency) of the electrolysis cells. brine containing them under high current densities of up to 40 A / dm2 and more. They also make it possible to work with high concentrations of soda (of the order of 140 to 200 g / l or more) in the catholyte, which limits the useful energy consumption to the subsequent concentration of soda.
- the diaphragms according to the invention comprise a fibrous sheet based on asbestos.
- the term “ply” is understood to mean a three-dimensional assembly or stack whose thickness is substantially less than the other dimensions, said assembly possibly having two parallel surfaces.
- These layers can be in various forms, generally determined by the geometry of the cathode elements with which they can be associated. In their use as microporous diaphragms in sodium chloride electrolysis cells and as an indication, their thickness is usually between 0.1 and 5 mm, one of their large dimensions, corresponding substantially to the height of the cathode element may reach 1 m, or even more and the other large dimension, substantially reflecting the perimeter of the element in question, will commonly reach several tens of meters.
- the fibers of the sheet are microconsolidated in the sense that they are, in a way, fixed to each other especially by a three-dimensional network of discrete points, which contributes to ensuring the sheet a porosity that is both fine and regular and great cohesion.
- fluoropolymer means a homopolymer or a copolymer derived at least in part from olefinic monomers which are totally substituted with fluorine atoms or totally substituted with a combination of fluorine atoms and at least one of chlorine, bromine or iodine per monomer.
- fluorinated homo- or copolymers can be constituted by polymers and copolymers derived from tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, bromotrifluoroethylene.
- Such fluorinated polymers can also contain up to 75 mole percent of units derived from other ethylenically unsaturated monomers containing at least as many fluorine atoms as carbon atoms, such as for example vinylidene (di) fluoride, vinyl and perfluoroalkyl esters, such as perfluoroalkoxyethylene.
- units derived from other ethylenically unsaturated monomers containing at least as many fluorine atoms as carbon atoms such as for example vinylidene (di) fluoride, vinyl and perfluoroalkyl esters, such as perfluoroalkoxyethylene.
- Polytetrafluoroethylene is the preferred binder for the diaphragms according to the invention.
- the fluoropolymer used here as a binder for a set of fibers may be present in the diaphragms in question in variable quantities within wide limits taking into account the fiber content and the nature of the various constituents of said diaphragms.
- the binder will preferably represent from 5 to 40% by weight in the sub-assembly (fibers + binder).
- the diaphragms according to the invention also contain from 20 to 95% by weight of fibers.
- organic fibers capable of entering into the constitution of the diaphragms according to the present invention mention may be made of fluoropolymer fibers in the sense indicated above and, more particularly polytetrafluoroethylene (PTFE) fibers.
- PTFE polytetrafluoroethylene
- the PTFE fibers which can be used in the context of the present invention can have variable dimensions; their diameter (D) and generally between 10 and 500 ⁇ m and their length (L) is such that the L / D ratio is between 5 and 500.
- D diameter
- L length
- Their preparation is described in US Patent No. 4,444,640 and this type of PTFE fiber is known to those skilled in the art.
- mineral fibers capable of entering into the constitution of the diaphragms according to the present invention mention may be made of zirconia, carbon, graphite or titanate fibers.
- the carbon or graphite fibers are in the form of filaments the diameter of which is generally less than 1 mm and preferably between 10 compris and 0.1 mm and the length of which is greater than 0.5 mm and , preferably between 1 and 20 mm.
- these carbon or graphite fibers have a distribution of monodispersed lengths, that is to say a distribution of lengths such that the length of at least 80% and, advantageously at least 90%, of the fibers. corresponds to the average fiber length to within ⁇ 20% and preferably to within ⁇ 10%.
- these carbon fibers advantageously represent at most 10% by weight of all the fibers.
- Titanate fibers are fibrous materials known in themselves. Thus the potassium titanate free are commercially available.
- Other free derivatives of potassium octatitanate K2Ti8O17 by partial replacement of titanium ions at oxidation state 4 by metal cations at oxidation state II such as magnesium and nickel cations, or at oxidation level III such as iron or chromium cations and by charge compensation provided by alkaline ions such as sodium and potassium cations, are described in French patent application No. 2,555,207.
- titanate fibers such as those made of potassium tetratitanate (K2Ti4O9) or derived therefrom can be used. If the titanate fibers can, without major drawbacks, represent up to 80% by weight of the fiber mixture used, when using carbon or graphite fibers it is preferable that their proportion in the fiber mixture does not not exceed 10% by weight.
- the diaphragms according to the invention also contain from 1 to 50% by weight of an oxohydroxide gel of at least one metal from groups IVA, IVB, VB and VIB of the periodic classification or series of lanthanides and actinides or the iron.
- the gel content represents from 2 to 25% by weight and, for a better embodiment, at least 3% by weight.
- the gel in question is distributed uniformly both on the surface of the diaphragms according to the invention and in their thickness.
- the gel content is determined after contact at 85 ° C. with an aqueous solution containing 140 g / l of sodium hydroxide and 160 g / l of sodium chloride. sodium, followed by cooling to 25 ° C, washing with water and drying for 24 hours at 100 ° C.
- zirconium thorium, cerium, tin, tantalum: niobium, uranium, chromium and iron.
- alkali metals such as sodium or potassium may be present in the diaphragms according to the invention.
- the diaphragms according to the invention contain an oxohydroxide gel of at least one metal from groups IVA and IVB.
- they contain a gel of titanium oxohydroxide, zirconium or cerium.
- the diaphragms according to the present invention have been defined by their essential constituents. It goes without saying that these materials may contain various other additives in minor quantities generally not exceeding 5% by weight which will have been added either simultaneously or successively during one or the other of the phases of their preparation. Thus, they may contain traces of surfactants or surfactants, pore-forming agents whose role is to regulate the porosity of the diaphragm, and / or thickeners, although in principle such agents are broken down or eliminated during the 'elaboration of said diaphragm.
- the diaphragms according to the present invention advantageously have a weight per unit area between 0.4 and 3 kg / m2 and, preferably between 0.7 and 1.9 kg / m2.
- the present invention also relates to the combination of a composite cathode element and a diaphragm, described above.
- the composite cathode (or precathode) elements in question result from the association of an elementary cathode constituted by a highly porous metal surface and a microporous fibrous sheet containing a significant proportion of electrically conductive fibers: the fibers being microconsolidated with a fluoropolymer.
- the cathode elements (to the precathode) preferred in the context of the present invention contain as electrically conductive fibers these carbon or graphite fibers. Preferably, these fibers have a monodispersed length distribution.
- fluoropolymer, binder of the precathode layer may be chosen from the fluoropolymers defined at the head of this specification, use is preferably made of polytetrafluoroethylene.
- association in question is a sort of assembly, from one face to the other of three layers, namely the elementary cathode, a first fibrous sheet containing the electrically conductive fibers, this ply having the intrinsic properties described in said European patent applications, and the diaphragm, said assembly constituting a coherent whole.
- the present invention also relates to a process for the preparation of the diaphragms which have just been described.
- aqueous medium a medium containing no other organic compounds than the constituents previously listed and the additives such as surfactants, surfactants and thickeners.
- the medium in question does not contain any organic solvent.
- an advantage presented both by the present process and by the diaphragms according to the invention lies in the fact that the presence of organic solvents is not necessary in the preparation of said diaphragms and that, therefore, it is not necessary to provide an additional step of evaporation of said solvent.
- oxohydroxide precursors of one of the metals of groups IVA, IVB, VB and VIB of the periodic table or of the lanthanide and actinide series means salts of said metals, which are as sparingly soluble in water as possible.
- the anion is chosen from the group comprising phosphate, pyrophosphate, hydrogenophosphate or polyphosphate anions, substituted if necessary by an alkali metal, and silicate.
- the fluoropolymer-based binder is generally in the form of a dry powder or an aqueous dispersion (latex), the dry extract of which represents from 30 to 80% by weight.
- the dispersion or suspension in question is generally highly diluted, the dry matter content (fibers, binder, precursors and additives) representing of the order of 1 to 15% of the weight of the assembly to facilitate handling on an industrial scale.
- additives can also be introduced into the dispersion, in particular surfactants or surfactants such as octoxynol (Triton X-100®), pore-forming agents such as silica, thickening agents such as natural or synthetic polysaccharides.
- surfactants or surfactants such as octoxynol (Triton X-100®), pore-forming agents such as silica, thickening agents such as natural or synthetic polysaccharides.
- the dispersion will contain all the essential constituents of the diaphragm with the exception of the oxohydroxide gel which was discussed above, but gel precursors in the sense indicated above will be present.
- the relative amounts of the essential constituents of the diaphragm to be introduced into the dispersion are readily determinable by those skilled in the art, given that they are substantially the same as those found in the diaphragm itself, with the exceptions of the pore-forming agent which is in principle eliminated by the action, for example, of electrolytic soda and of the precursor of oxohydroxide gel.
- the precursor is completely transformed into an oxohydroxide gel, the "active" part of which, obtained after washing and drying the gel, represents from 10 to 90% by weight of the precursor introduced.
- the content of PTFE powder represents from 5 to 40% by weight of the whole (PTFE powder + fibers).
- the content by weight of at least one oxohydroxide gel precursor in said dry extract will be between 5 and 40%.
- the sheet is then formed by filtration under programmed vacuum, dispersion through a porous material such as fabrics or grids whose mesh vacuum, perforations or porosity may be between 1 ⁇ m and 2 mm.
- the vacuum program can be continuous or in stages, from atmospheric pressure to final pressure (0.01 to 0.5 bar absolute).
- the assembly After elimination of the liquid medium and, if necessary the drying of the sheet thus formed, the assembly is sintered.
- Sintering is carried out in a manner known per se at a temperature above the melting or softening point of the fluoropolymer, binder of said sheet. This step which allows the consolidation of the sheet, is then followed by a treatment step by which the sheet is brought into contact with an aqueous solution of alkali hydroxide, and more particularly with an electrolytic soda solution.
- This contacting can be carried out in situ, that is to say during the positioning of the consolidated sheet in the electrolysis cell, in contact with the electrolytic soda solution.
- the treatment is advantageously carried out in contact with an aqueous sodium hydroxide solution whose concentration is between 40 and 200 g / l and at a temperature between 20 and 95 ° C.
- the precursors of the oxohydroxide gel are capable of undergoing various transformations during the various operations for producing the diaphragm, and in particular a non-destructive transformation during the sintering operation, that is to say only leading loss of hydration or constitution water molecules; they will be transformed by the above-mentioned treatment step into a fresh gel of oxohydroxide of the metal concerned, impregnated with electrolyte and water.
- the filtration of the dispersion or suspension is carried out through a cathode (or precathode) element in the sense indicated in the present specification.
- Such a method has the advantage of contributing to the development of associations of strong cohesion.
- Another advantage resides in its great simplicity of implementation of the fact that a single sintering step is sufficient to develop associations of strong cohesion and of the fact that a single step makes it possible to eliminate the porogens, both from the precathode layer. than the diaphragm, and to give birth to the fresh gay oxohydroxide of the metal in question.
- PTFE is used as binder of the precathode layer and of the diaphragm.
- the total volume of water is calculated so that the weight percentage of dry matter (B + D + E + F) / A is approximately 4.5%.
- the solution is left for 48 hours
- the volume of solution required is withdrawn so that it contains the quantity of dry extract which it is intended to deposit to form the diaphragm (of the order of 1.3 kg / m2).
- the suspension is reacted for 30 min before use.
Abstract
Description
La présente invention concerne des diaphragmes comprenant des fibres d'amiante pour des cellules d'électrolyse, l'association de tels diaphragmes à un élément cathodique et un procédé d'obtention de tels diaphragmes et d'association de tels diaphragmes à un élement cathodique.The present invention relates to diaphragms comprising asbestos fibers for electrolytic cells, the association of such diaphragms with a cathode element and a method of obtaining such diaphragms and of association of such diaphragms with a cathode element.
Elle vise plus particulièrement un perfectionnement à des diaphragmes susceptibles d'être produits par voie humide, à base de fibres d'amiante, pour des cellules d'électrolyse chlore-soude.It relates more particularly to an improvement to diaphragms capable of being produced by the wet route, based on asbestos fibers, for chlor-soda electrolysis cells.
Depuis très longtemps, on utilise des fibres d'amiante comme matière conventionnelle de réalisation des diaphragmes employés dans des cellules d'électrolyse. Ces diaphragmes sont formés par dépôt sur une cathode perméable aux électrolytes, de fibres d'amiante contenues dans une bouillie aqueuse, l'opération de dépôt étant réalisée sous vide. Ainsi dans le brevet français n° 2 213 805, il a été proposé de préparer des séparateurs microporeux par dépôt d'une couche d'amiante, ladite couche étant consolidée par un polymère fluoré. La porosité d'une telle couche peut être mieux contrôlée par addition d'un agent porogène conformément à l'enseignement du brevet français n° 2 229 739.Asbestos fibers have been used for a very long time as a conventional material for producing diaphragms used in electrolysis cells. These diaphragms are formed by depositing asbestos fibers contained in an aqueous slurry on an electrolyte-permeable cathode, the deposition operation being carried out under vacuum. Thus in French Patent No. 2,213,805, it has been proposed to prepare microporous separators by depositing a layer of asbestos, said layer being consolidated by a fluoropolymer. The porosity of such a layer can be better controlled by adding a blowing agent in accordance with the teaching of French Patent No. 2,229,739.
Comme cela est bien connu de l'homme de l'art, ce type de préparation de séparateurs microporeux par dépôt sous vide d'une bouillie aqueuse renfermant des fibres et un liant présente un très grand intérêt tant sur le plan technique que sur le plan économique. Toutefois la qualité des séparateurs ainsi obtenus n'est pas pleinement satisfaisante.As is well known to those skilled in the art, this type of preparation of microporous separators by vacuum deposition of an aqueous slurry containing fibers and a binder is of very great interest both technically and technically. economic. However, the quality of the separators thus obtained is not fully satisfactory.
En effet, le rendement Faraday est insuffisant ce qui se traduit par une consommation d'énergie, par tonne de chlore produit, importante. Plus la concentration en soude est élevée, plus le rendement en cause baisse dans une installation industrielle. Or il est du plus haut intérêt de pouvoir travailler avec de la soude concentrée pour pouvoir diminuer le coût énergétique de l'évaporation nécessaire ensuite à la concentration de la soude produite. Il serait donc souhaitable de disposer d'un diaphragme perfectionné à base de fibres d'amiante, susceptible d'être produit par voie humide.Indeed, the Faraday yield is insufficient, which results in an energy consumption, per ton of chlorine produced, significant. The higher the sodium hydroxide concentration, the more the yield in question decreases in an industrial installation. However, it is of the highest interest to be able to work with concentrated soda in order to be able to reduce the energy cost of the evaporation then necessary for the concentration of the soda produced. It would therefore be desirable to have an improved diaphragm based on asbestos fibers, capable of being produced by the wet process.
Dans la demande de brevet européen n° 132 425 il a été proposé des éléments cathodiques, matériaux composites résultant de l'association d'une cathode élémentaire constituée par une surface métallique fortement poreuse telle une grille métallique présentant un vide de maille compris entre 20 µm et 5 mm et d'une nappe renfermant des fibres et un liant, l'association et la nappe résultant de l'aspiration sous vide programmé d'une suspension, contenant essentiellement des fibres conductrices de l'électricité et un polymère fluoré, directement au travers de ladite cathode élémentaire, suivie du séchage, puis de la fusion du liant. De tels matériaux composites sont susceptibles de constituer la cathode elle-même d'une cellule d'électrolyse et peuvent être associés à un diaphragme, le diaphragme pouvant être fabriqué directement par voie humide sur le composite.In European patent application No. 132 425, cathode elements, composite materials resulting from the association of an elementary cathode constituted by a highly porous metal surface such as a metal grid having a mesh void of between 20 μm, have been proposed. and 5 mm and of a sheet containing fibers and a binder, the association and the sheet resulting from the suction under programmed vacuum of a suspension, essentially containing electrically conductive fibers and a fluorinated polymer, directly to the through said elementary cathode, followed by drying, then melting of the binder. Such composite materials are capable of constituting the cathode itself of an electrolysis cell and can be associated with a diaphragm, the diaphragm being able to be manufactured directly by wet process on the composite.
Divers perfectionnements ont été apportés tant aux matériaux composites eux-mêmes qu'à leur procédé de fabrication.Various improvements have been made both to the composite materials themselves and to their manufacturing process.
Dans la demande de brevet européen n° 214 066 il a été proposé des matériaux renfermant des fibres de carbone présentant une distribution monodispersée de longueurs, matériaux dont la qualité et les propriétés sont très sensiblement améliorées, ce qui se traduit par un rapport performance/épaisseur beaucoup plus favorable.In European patent application No. 214 066, materials containing carbon fibers have been proposed having a monodispersed distribution of lengths, materials whose quality and properties are very significantly improved, which results in a performance / thickness ratio. much more favorable.
Dans la demande de brevet européen n° 296 076 il a été proposé des matériaux électroactivés renfermant un agent électrocatalytique uniformément réparti dans leur masse, ledit agent étant choisi parmi les métaux de Raney et les alliages de Raney dont on a éliminé la majeure partie du (des) métal (métaux) facilement éliminable(s).In European patent application No. 296 076, electroactivated materials containing an electrocatalytic agent uniformly distributed in their mass have been proposed, said agent being chosen from Raney metals and Raney alloys from which most of the ( easily removable metal (s).
L'ensemble des éléments cathodiques proposés qui assurent une répartition appréciable du courant est susceptible d'être utilisé dans une cellule d'électrolyse qui comprendra une membrane ou un diaphragme entre les compartiments anodique et cathodique. Des détails techniques complémentaires pourront être trouvés dans les demandes de brevets européens précitées, qui sont incorporées par référence pour éviter de plus amples développements sur lesdits éléments cathodiques.All of the cathode elements proposed which ensure an appreciable distribution of the current can be used in an electrolysis cell which will include a membrane or a diaphragm between the anode and cathode compartments. Additional technical details can be found in the aforementioned European patent applications, which are incorporated by reference to avoid further development on said cathode elements.
Il a maintenant été trouvé qu'il est possible de préparer des séparateurs microporeux comprenant de l'amiante améliorés, par voie humide, par aspiration sous vide d'une bouillie aqueuse renfermant des fibres à travers un support poreux et d'obtenir un séparateur microporeux ne présentant pas les inconvénients précités.It has now been found that it is possible to prepare microporous separators comprising improved asbestos, wet, by vacuum suction of an aqueous slurry containing fibers to through a porous support and to obtain a microporous separator which does not have the aforementioned drawbacks.
La présente invention a donc pour objet un diaphragme microporeux susceptible d'être formé in-situ par voie humide comprenant une nappe fibreuse, comprenant de l'amiante dont les fibres sont microconsolidées par un polymère fluoré, l'ensemble étant fritté, ladite nappe renfermant essentiellement :
- de 3 à 35 % en poids de polymère fluoré, liant des fibres,
- de 1 à 50 % en poids d'un gel d'oxohydroxyde d'au moins un métal des groupes IVA, IVB, VB et ViB de la classification périodique ou des séries des lanthanides et des actinides, ou le fer,
- de 20 à 95 % en poids de fibres, les fibres d'amiante représentant au moins 1 % en poids desdites fibres.
- from 3 to 35% by weight of fluoropolymer, fiber-binding,
- from 1 to 50% by weight of an oxohydroxide gel of at least one metal from groups IVA, IVB, VB and ViB of the periodic table or of the series of lanthanides and actinides, or iron,
- from 20 to 95% by weight of fibers, the asbestos fibers representing at least 1% by weight of said fibers.
La présente invention a également pour objet l'association d'un tel diaphragme et d'un élément cathodique composite.The present invention also relates to the association of such a diaphragm and a composite cathode element.
La présente invention a également pour objet un procédé de préparation de tels diaphragmes comprenant essentiellement la succession d'étapes suivantes :
- a) la préparation en milieu essentiellement aqueux d'une dispersion comprenant les fibres, le liant à base de polymère fluoré sous forme de particules, au moins un précurseur d'oxohydroxyde d'au moins l'un des métaux des groupes IVA, IVB, VB et VIB de la classification périodique ou des séries des lanthanides et des actinides ou ler fer, sous forme de particules et, le cas échéant des additifs,
- b) le dépôt d'une nappe par filtration sous vide programmé de ladite dispersion à travers un matériau poreux,
- c) l'élimination du milieu liquide et, le cas échéant, le séchage de la nappe ainsi formée,
- d) le frittage de la nappe et,
- e) le traitement, le cas échéant, in-situ dans les conditions de l'électrolyse, par une solution aqueuse d'hydroxyde alcalin. Le matériau poreux (support) en cause peut être un élément cathodique composite et le procédé permet alors de réaliser une association au sens de la présente invention.
- a) the preparation, in essentially aqueous medium, of a dispersion comprising the fibers, the binder based on fluorinated polymer in the form of particles, at least one oxohydroxide precursor of at least one of the metals of groups IVA, IVB, VB and VIB of the periodic table or series of lanthanides and actinides or iron, in the form of particles and, where appropriate, additives,
- b) the deposition of a sheet by programmed vacuum filtration of said dispersion through a porous material,
- c) elimination of the liquid medium and, if necessary, drying of the sheet thus formed,
- d) sintering the web and,
- e) the treatment, if necessary, in situ under the conditions of electrolysis, with an aqueous solution of alkali hydroxide. The porous material (support) in question can be a composite cathode element and the method then makes it possible to make an association within the meaning of the present invention.
La présente invention a également pour objet un procédé de préparation de telles associations, comprenant essentiellement la succession d'étapes suivantes :
- a) le dépôt d'une nappe précathodique par filtration sous vide programmé d'une dispersion en milieu essentiellement aqueux de fibres, de liant sous forme de particules et, le cas échéant d'additifs, à travers une cathode élémentaire constituée d'une surface métallique présentant un vide de maille ou des perforations compris entre 20 µm et 5 mm,
- b) l'élimitation du milieu liquide et, le cas échéant, le séchage de la nappe ainsi formée,
- c) la filtration sous vide programmé, à travers la nappe précathodique, d'une dispersion en milieu essentiellement aqueux de fibres, de liant à base d'un polymère fluoré sous forme de particules, d'au moins un précurseur d'oxohydroxyde d'au moins l'un des métaux des groupes IVA, IVB, VB et VIB de la classification périodique ou des séries des lanthanides et des actinides, ou le fer, sous forme de particules, et, le cas échéant des additifs,
- d) l'élimination du milieu liquide et, le cas échéant, le séchage de la nappe ainsi formée,
- e) le frittage de l'ensemble et,
- f) le traitement, le cas échéant in-situ dans les conditions de l'électrolyse, par une solution aqueuse d'hydroxyde alcalin.
- a) the deposition of a precathode layer by programmed vacuum filtration of a dispersion in an essentially aqueous medium of fibers, of binder in the form of particles and, where appropriate of additives, through an elementary cathode constituted by a surface metallic with a mesh void or perforations between 20 µm and 5 mm,
- b) the elimination of the liquid medium and, if necessary, the drying of the sheet thus formed,
- c) filtration under programmed vacuum, through the precathode layer, of a dispersion in an essentially aqueous medium of fibers, of binder based on a fluoropolymer in the form of particles, of at least one oxohydroxide precursor at least one of the metals of groups IVA, IVB, VB and VIB of the Periodic Table or of the series of lanthanides and actinides, or iron, in the form of particles, and, where appropriate, additives,
- d) elimination of the liquid medium and, if necessary, drying of the sheet thus formed,
- e) sintering the assembly and,
- f) treatment, if necessary in situ under the conditions of electrolysis, with an aqueous solution of alkali hydroxide.
Les diaphragmes selon la présente invention présentent une stabilité dimensionnelle appréciable, une porosité fine et régulière et une mouillabilité permanente. Les diaphragmes selon la présente invention présentent an outre des tensions de fonctionnement très basses ce qui constitue un autre avantage de la présente invention.The diaphragms according to the present invention exhibit appreciable dimensional stability, fine and regular porosity and permanent wettability. The diaphragms according to the present invention also have very low operating voltages, which constitutes another advantage of the present invention.
Les diaphragmes selon la présente invention sont susceptibles d'être obtenus par des voies, classiquement utilisées dans l'industrie, de dépôts d'une suspension par aspiration sous vide et permettent le fonctionnement efficace (rendement en courant élevé) des cellules d'électrolyse de saumure les renfermant sous des densités de courant élevées pouvant atteindre 40 A/dm² et davantage. Ils permettent en outre de travailler avec des concentrations de soude élevées (de l'ordre de 140 à 200 g/l ou davantage) dans le catholyte, ce qui limite la consommation énergétique utile à la concentration ultérieure de la soude.The diaphragms according to the present invention are capable of being obtained by means, conventionally used in industry, of deposits of a suspension by vacuum suction and allow the efficient operation (high current efficiency) of the electrolysis cells. brine containing them under high current densities of up to 40 A / dm² and more. They also make it possible to work with high concentrations of soda (of the order of 140 to 200 g / l or more) in the catholyte, which limits the useful energy consumption to the subsequent concentration of soda.
Les diaphragmes selon l'invention comprennent une nappe fibreuse à base d'amiante. Par nappe on entend un assemblage ou empilement tridimensionnel dont l'épaisseur est sensiblement plus faible que les autres dimensions, ledit assemblage pouvant, le cas échéant, présenter deux surfaces parallèles. Ces nappes peuvent se présenter sous des formes diverses, généralement déterminées par la géométrie des éléments cathodiques auxquels elles pourront être associées. Dans leur utilisation comme diaphragmes microporeux dans des cellules d'électrolyse du chlorure de sodium et à titre indicatif, leur épaisseur est usuellement comprise entre 0,1 et 5 mm, l'une de leurs grandes dimensions, correspondant sensiblement à la hauteur de l'élément cathodique pourra atteindre 1 m, voire d'avantage et l'autre grande dimension, reflétant sensiblement le périmètre de l'élément en cause, atteindra couramment plusieurs dizaines de mètres.The diaphragms according to the invention comprise a fibrous sheet based on asbestos. The term “ply” is understood to mean a three-dimensional assembly or stack whose thickness is substantially less than the other dimensions, said assembly possibly having two parallel surfaces. These layers can be in various forms, generally determined by the geometry of the cathode elements with which they can be associated. In their use as microporous diaphragms in sodium chloride electrolysis cells and as an indication, their thickness is usually between 0.1 and 5 mm, one of their large dimensions, corresponding substantially to the height of the cathode element may reach 1 m, or even more and the other large dimension, substantially reflecting the perimeter of the element in question, will commonly reach several tens of meters.
Les fibres de la nappe sont microconsolidées en ce sens qu'elles sont, en quelque sorte, fixées les unes aux autres surtout par un réseau tridimensionnel de points discrets, ce qui contribue à assurer à la nappe une porosité à la fois fine et régulière et une très grande cohésion.The fibers of the sheet are microconsolidated in the sense that they are, in a way, fixed to each other especially by a three-dimensional network of discrete points, which contributes to ensuring the sheet a porosity that is both fine and regular and great cohesion.
Ces nappes (ou empilements fibreux) selon l'invention sont à base d'amiante et renferment essentiellement, comme indiqué en tête du présent mémoire :
- de 3 à 35 % en poids de polymères fluoré, liant des fibres,
- de 1 à 50 % en poids d'un gai d'oxohydroxyde d'au moins un métal des groupes IVA, IVB, VB et ViB de la classification périodique ou des séries des lanthanides et des actinides, ou le fer,
- de 20 à 95 % en poids de fibres, les fibres d'amiante représentant au moins 1 % en poids desdites fibres.
- from 3 to 35% by weight of fluoropolymers, binding fibers,
- from 1 to 50% by weight of a gay oxohydroxide of at least one metal from groups IVA, IVB, VB and ViB of the periodic table or of the series of lanthanides and actinides, or iron,
- from 20 to 95% by weight of fibers, the asbestos fibers representing at least 1% by weight of said fibers.
Par polymère fluoré on entend un homopolymère ou un copolymère dérivé au moins en partie de monomères oléfiniques totalement substitués avec des atomes de fluor ou totalement substitués avec une combinaison d'atomes de fluor et de l'un au moins des atomes de chlore, brome ou iode par monomère.The term “fluoropolymer” means a homopolymer or a copolymer derived at least in part from olefinic monomers which are totally substituted with fluorine atoms or totally substituted with a combination of fluorine atoms and at least one of chlorine, bromine or iodine per monomer.
Des exemples d'homo- ou copolymères fluorés peuvent être constitués par les polymères et copolymères dérivés de tétrafluoroéthylène, hexafluoropropylène, chlorotrifluoroéthylène, bromotrifluoroéthylène.Examples of fluorinated homo- or copolymers can be constituted by polymers and copolymers derived from tetrafluoroethylene, hexafluoropropylene, chlorotrifluoroethylene, bromotrifluoroethylene.
De tels polymères fluorés peuvent aussi contenir jusqu'à 75 moles pour cent de motifs dérivés d'autres monomères éthyléniquement insaturés contenant au moins autant d'atomes de fluor que d'atomes de carbone, comme par exemple le (di)fluorure de vinylidène, les esters de vinyle et de perfluoroalkyle, tel que le perfluoroalcoxyéthylène.Such fluorinated polymers can also contain up to 75 mole percent of units derived from other ethylenically unsaturated monomers containing at least as many fluorine atoms as carbon atoms, such as for example vinylidene (di) fluoride, vinyl and perfluoroalkyl esters, such as perfluoroalkoxyethylene.
On peut naturellement utiliser dans l'invention plusieurs homo- ou copolymères fluorés tels que définis ci-avant. Il va sans dire qu'on ne sortirait pas du cadre de l'invention en associant à ces polymères fluorés une faible quantité, par exemple jusqu'à 10 ou 15 % en poids de polymères dont la molécule ne renferme pas d'atomes de fluor, comme par exemple du polypropylène.It is naturally possible to use in the invention several fluorinated homo- or copolymers as defined above. It goes without saying that it would not go beyond the scope of the invention to combine with these fluorinated polymers a small amount, for example up to 10 or 15% by weight of polymers whose molecule does not contain fluorine atoms , such as polypropylene.
Le polytétrafluoroéthylène est le liant préféré des diaphragmes selon l'invention.Polytetrafluoroethylene is the preferred binder for the diaphragms according to the invention.
Le polymère fluoré utilisé ici comme liant d'un ensemble de fibres peut être présent dans les diaphragmes en cause en des quantités variables dans de larges limites compte-tenu de la teneur en fibres et de la nature des divers constituants desdits diaphragmes.The fluoropolymer used here as a binder for a set of fibers may be present in the diaphragms in question in variable quantities within wide limits taking into account the fiber content and the nature of the various constituents of said diaphragms.
Toutefois, pour assurer une bonne consolidation de l'ensemble, le liant représentera, de préférence de 5 à 40 % en poids dans le sous ensemble (fibres + liant).However, to ensure good consolidation of the assembly, the binder will preferably represent from 5 to 40% by weight in the sub-assembly (fibers + binder).
Les diaphragmes selon l'invention renferment également de 20 à 95 % en poids de fibres.The diaphragms according to the invention also contain from 20 to 95% by weight of fibers.
Ces fibres dont au moins 1 % (en poids) et, de préférence au moins 40 % (en poids) sont des fibres d'amiante, peuvent être de nature diverses. En effet il est possible d'utiliser des fibres minérales différentes, des fibres organiques ou des mélanges de fibres minérales et de fibres organiques. Parmi les fibres organiques susceptibles d'entrer dans la constitution des diaphragmes selon la présente invention on peut citer les fibres de polymères fluorés au sens indiqué précédemment et, plus particulièrement des fibres de polytétrafluoroéthylène (PTFE).These fibers of which at least 1% (by weight) and, preferably at least 40% (by weight) are asbestos fibers, can be of various nature. Indeed it is possible to use different mineral fibers, organic fibers or mixtures of mineral fibers and organic fibers. Among the organic fibers capable of entering into the constitution of the diaphragms according to the present invention, mention may be made of fluoropolymer fibers in the sense indicated above and, more particularly polytetrafluoroethylene (PTFE) fibers.
Les fibres de PTFE, susceptibles d'être utilisées dans le cadre de la présente invention peuvent présenter des dimensions variables ; leur diamètre (D) et généralement compris entre 10 et 500 µm et leur longueur (L) est telle que le rapport L/D soit compris entre 5 et 500. De préférence, on recourt à des fibres de PTFE dont les dimensions moyennes sont comprises entre 1 et 4 mm pour la longueur et entre 50 et 200 µm pour le diamètre. Leur préparation est décrite dans le brevet américain n° 4,444,640 et ce type de fibres de PTFE est connu des hommes de l'art.The PTFE fibers which can be used in the context of the present invention can have variable dimensions; their diameter (D) and generally between 10 and 500 μm and their length (L) is such that the L / D ratio is between 5 and 500. Preferably, use is made of PTFE fibers whose average dimensions are between 1 and 4 mm for the length and between 50 and 200 µm for the diameter. Their preparation is described in US Patent No. 4,444,640 and this type of PTFE fiber is known to those skilled in the art.
Parmi les fibres minérales susceptibles d'entrer dans la constitution des diaphragmes selon la présente invention on peut citer les fibres de zircone, de carbone, de graphite ou de titanate.Among the mineral fibers capable of entering into the constitution of the diaphragms according to the present invention, mention may be made of zirconia, carbon, graphite or titanate fibers.
Les fibres de carbone ou de graphite se présentent sous forme de filaments dont le diamètre est généralement inférieur à 1 mm et, de préférence, compris entre 10⁻⁵ et 0,1 mm et, dont la longueur est supérieure à 0,5 mm et, de préférence comprise entre 1 et 20 mm.The carbon or graphite fibers are in the form of filaments the diameter of which is generally less than 1 mm and preferably between 10 compris and 0.1 mm and the length of which is greater than 0.5 mm and , preferably between 1 and 20 mm.
De préférence, ces fibres de carbone ou de graphite présentent une distribution de longueurs monodispersée, c'est-à-dire une distribution de longueurs telles que la longueur d'au moins 80 % et, avantageusement d'au moins 90 %, des fibres correspond à la longueur moyenne des fibres à ± 20 % près et, de préférence à ± 10 % près. Lorsqu'elles sont présentes, ces fibres de carbone représentent avantageusement au maximum 10 % en poids de l'ensemble des fibres.Preferably, these carbon or graphite fibers have a distribution of monodispersed lengths, that is to say a distribution of lengths such that the length of at least 80% and, advantageously at least 90%, of the fibers. corresponds to the average fiber length to within ± 20% and preferably to within ± 10%. When present, these carbon fibers advantageously represent at most 10% by weight of all the fibers.
Les fibres de titanate sont des matériaux fibreux connus en eux-mêmes. Ainsi les libres de titanate de potassium sont disponibles dans le commerce. D'autres libres dérivant de l'octatitanate de potassium K₂Ti₈O₁₇ par remplacement partiel des ions titane au degré d'oxydation 4 par des cations métalliques au degré d'oxydation II tels les cations magnésium et nickel, ou au degré d'oxydation III tels les cations fer ou chrome et par compensation de charge assurée par des ions alcalins tels les cations sodium et potassium, sont décrites dans la demande de brevet français n° 2 555 207.Titanate fibers are fibrous materials known in themselves. Thus the potassium titanate free are commercially available. Other free derivatives of potassium octatitanate K₂Ti₈O₁₇ by partial replacement of titanium ions at oxidation state 4 by metal cations at oxidation state II such as magnesium and nickel cations, or at oxidation level III such as iron or chromium cations and by charge compensation provided by alkaline ions such as sodium and potassium cations, are described in French patent application No. 2,555,207.
D'autres fibres de titanates telles celles en tétratitanate de potassium (K₂Ti₄O₉) ou en dérivant, peuvent être utilisées. Si les fibres de titanates peuvent, sans inconvénients majeurs, représenter jusqu'à 80 % en poids du mélange de fibres utilisé, lorsqu'on recourt à des fibres de carbone ou de graphite il est préférable que leur proportion dans le mélange de fibres n'excède pas 10 % en poids.Other titanate fibers such as those made of potassium tetratitanate (K₂Ti₄O₉) or derived therefrom can be used. If the titanate fibers can, without major drawbacks, represent up to 80% by weight of the fiber mixture used, when using carbon or graphite fibers it is preferable that their proportion in the fiber mixture does not not exceed 10% by weight.
Bien entendu des mélanges de fibres minérales différentes par leur nature peuvent être utilisés.Of course, mixtures of mineral fibers which are different in nature can be used.
Les diaphragmes selon l'invention renferment également de 1 à 50 % en poids d'un gel d'oxohydroxyde d'au moins un métal des groupes IVA, IVB, VB et VIB de la classification périodique ou des séries des lanthanides et des actinides ou le fer. De préférence, la teneur en gel représente de 2 à 25 % en poids et, pour une meilleure réalisation, au moins 3 % en poids.The diaphragms according to the invention also contain from 1 to 50% by weight of an oxohydroxide gel of at least one metal from groups IVA, IVB, VB and VIB of the periodic classification or series of lanthanides and actinides or the iron. Preferably, the gel content represents from 2 to 25% by weight and, for a better embodiment, at least 3% by weight.
Le gel en cause est réparti uniformément tant à la surface des diaphragmes selon l'invention que dans leur épaisseur.The gel in question is distributed uniformly both on the surface of the diaphragms according to the invention and in their thickness.
La teneur en gel, initialement imbibé de chlorure de sodium, d'hydroxyde de sodium et d'eau, est déterminée après contact à 85°C avec une solution aqueuse à 140 g/l de soude et à 160 g/l de chlorure de sodium, suivi du refroidissement à 25°C, du lavage à l'eau et du séchage pendant 24 heures à 100°C.The gel content, initially soaked in sodium chloride, sodium hydroxide and water, is determined after contact at 85 ° C. with an aqueous solution containing 140 g / l of sodium hydroxide and 160 g / l of sodium chloride. sodium, followed by cooling to 25 ° C, washing with water and drying for 24 hours at 100 ° C.
Parmi les métaux des groupes et séries de la classification périodique énumérés ci-avant on peut citer à titre d'exemples : le titane, le zirconium: le thorium, le cérium, l'étain, le tantale: le niobium, l'uranium, le chrome et le fer. Bien entendu des mélanges de tels métaux ou de tels métaux et des métaux alcalins tels le sodium ou le potassium peuvent être présents dans les diaphragmes selon l'invention.Among the metals of the groups and series of the periodic classification listed above, there may be mentioned as examples: titanium, zirconium: thorium, cerium, tin, tantalum: niobium, uranium, chromium and iron. Of course, mixtures of such metals or of such metals and of alkali metals such as sodium or potassium may be present in the diaphragms according to the invention.
De préférence, les diaphragmes selon l'invention renferment un gel d'oxohydroxyde d'au moins un métal des groupes IVA et IVB.Preferably, the diaphragms according to the invention contain an oxohydroxide gel of at least one metal from groups IVA and IVB.
De préférence, ils renferment un gel d'oxohydroxyde de titane, de zirconium ou de cérium.Preferably, they contain a gel of titanium oxohydroxide, zirconium or cerium.
Les diaphragmes selon la présente invention ont été définis par leurs constituants essentiels. Il va de soi que ces matériaux peuvent renfermer divers autres additifs en quantité mineure n'excédant généralement pas 5 % en poids qui auront été ajoutés soit simultanément soit successivement au cours de l'une ou l'autre des phases de leur élaboration. Ainsi ils pourront renfermer des traces d'agents tensioactifs ou surfactifs, d'agents porogènes dont le rôle est de régler la porosité du diaphragme, et/ou d'épaississants, bien qu'en principe de tels agents soient décomposés ou éliminés lors de l'élaboration dudit diaphragme.The diaphragms according to the present invention have been defined by their essential constituents. It goes without saying that these materials may contain various other additives in minor quantities generally not exceeding 5% by weight which will have been added either simultaneously or successively during one or the other of the phases of their preparation. Thus, they may contain traces of surfactants or surfactants, pore-forming agents whose role is to regulate the porosity of the diaphragm, and / or thickeners, although in principle such agents are broken down or eliminated during the 'elaboration of said diaphragm.
Les diaphragmes selon la présente invention présentent avantageusement un poids par unité de surface compris entre 0,4 et 3 kg/m² et, de préférence entre 0,7 et 1,9 kg/m².The diaphragms according to the present invention advantageously have a weight per unit area between 0.4 and 3 kg / m² and, preferably between 0.7 and 1.9 kg / m².
La présente invention a également pour objet l'association d'un élément cathodique composite et d'un diaphragme, décrit ci-avant.The present invention also relates to the combination of a composite cathode element and a diaphragm, described above.
Les éléments cathodiques (ou précathodiques) composites en cause résultent de l'association d'une cathode élémentaire constituée par une surface métallique fortement poreuse et d'une nappe fibreuse microporeuse renfermant une proportion notable de fibres conductrices de l'électricité: les fibres étant microconsolidées par un polymère fluoré.The composite cathode (or precathode) elements in question result from the association of an elementary cathode constituted by a highly porous metal surface and a microporous fibrous sheet containing a significant proportion of electrically conductive fibers: the fibers being microconsolidated with a fluoropolymer.
Les éléments cathodiques (au précathodiques) préférés dans le cadre de la présente invention renferment comme fibres conductrices de l'électricité ces fibres de carbone ou de graphite. De préférence, ces fibres présentent une répartition des longueurs monodispersée.The cathode elements (to the precathode) preferred in the context of the present invention contain as electrically conductive fibers these carbon or graphite fibers. Preferably, these fibers have a monodispersed length distribution.
Bien que le polymère fluoré, liant de la nappe précathodique puisse être choisi parmi les polymères fluorés définis en tête du présent mémoire, on recourt de préférence, au polytétrafluoroéthylène.Although the fluoropolymer, binder of the precathode layer may be chosen from the fluoropolymers defined at the head of this specification, use is preferably made of polytetrafluoroethylene.
Ces éléments cathodiques (ou précathodiques) composites sont décrits dans les demandes de brevet européen précédemment incorporées par référence.These composite cathodic (or precathodic) elements are described in the European patent applications previously incorporated by reference.
Il va de soi, que l'association en cause est en quelque sorte un assemblage, d'une face vers l'autre de trois couches, à savoir la cathode élémentaire, une première nappe fibreuse renfermant les fibres conductrices de l'électricité, cette nappe présentant dos propriétés intrinsèques décrites dans lesdites demandes de brevet européen, et le diaphragme, ledit assemblage constituant un ensemble cohérent.It goes without saying that the association in question is a sort of assembly, from one face to the other of three layers, namely the elementary cathode, a first fibrous sheet containing the electrically conductive fibers, this ply having the intrinsic properties described in said European patent applications, and the diaphragm, said assembly constituting a coherent whole.
Comme indiqué en tête du présent mémoire la présente invention a également pour objet un procédé de préparation des diaphragmes qui viennent d'être décrits.As indicated at the beginning of this specification, the present invention also relates to a process for the preparation of the diaphragms which have just been described.
Le procédé de préparation des diaphragmes en cause comprend essentiellement la succession d'étapes suivantes :
- a) la préparation en milieu essentiellement aqueux d'une dispersion comprenant les fibres, le liant à base de polymère fluoré sous forme de particules, au moins un précurseur d'oxohydroxyde d'au moins l'un des métaux des groupes IVA, IVB, VB et VIB de la classification périodique su des séries des lanthanides et des actinides, ou le fer, sous forme de particules et, le cas échéant des additifs,
- b) le dépôt d'une nappe par filtration sous vide programmé de ladite dispersion à travers un matériau poreux,
- c) l'élimination du milieu liquide et, le cas échéant, le séchage de la nappe ainsi formée,
- d) le frittage de la nappe et,
- e) le traitement, le cas échéant, in-situ dans les conditions de l'électrolyse, par une solution aqueuse d'hydroxyde alcalin.
- a) the preparation, in essentially aqueous medium, of a dispersion comprising the fibers, the binder based on fluorinated polymer in the form of particles, at least one oxohydroxide precursor of at least one of the metals of groups IVA, IVB, VB and VIB of the periodic table of the series of lanthanides and actinides, or iron, in the form of particles and, where appropriate, additives,
- b) the deposition of a tablecloth by programmed vacuum filtration of said dispersion through a porous material,
- c) elimination of the liquid medium and, if necessary, drying of the sheet thus formed,
- d) sintering the web and,
- e) the treatment, if necessary, in situ under the conditions of electrolysis, with an aqueous solution of alkali hydroxide.
Par milieu essentiellement aqueux on entend un milieu ne renfermant pas d'autres composés organiques que les constituants précédemment énumérés et les additifs tels les tensioactifs, surfactifs et épaississants. Ainsi le milieu en cause ne renferme pas de solvant organique.By essentially aqueous medium is meant a medium containing no other organic compounds than the constituents previously listed and the additives such as surfactants, surfactants and thickeners. Thus the medium in question does not contain any organic solvent.
En effet, si la présence de solvants organiques n'est pas nuisible en elle-même, un avantage présenté tant par le présent procédé que par les diaphragmes selon l'invention réside dans le fait que la présence de solvants organiques n'est pas nécessaire à l'élaboration desdits diaphragmes et que, de ce fait, il n'est pas nécessaire de prévoir une étape supplémentaire d'évaporation dudit solvant.Indeed, if the presence of organic solvents is not harmful in itself, an advantage presented both by the present process and by the diaphragms according to the invention lies in the fact that the presence of organic solvents is not necessary in the preparation of said diaphragms and that, therefore, it is not necessary to provide an additional step of evaporation of said solvent.
Par précurseurs d'oxohydroxyde de l'un des métaux des groupes IVA, IVB, VB et VIB de la classification périodique ou des séries des lanthanides et des actinides, on entend des sels desdits métaux, aussi peu solubles que possible dans l'eau dont l'anion est choisi dans le groupe comprenant les anions phosphate, pyrophosphate, hydrogénophosphate ou polyphosphate, substitué le cas échéant par un métal alcalin, et silicate.The expression “oxohydroxide precursors” of one of the metals of groups IVA, IVB, VB and VIB of the periodic table or of the lanthanide and actinide series means salts of said metals, which are as sparingly soluble in water as possible. the anion is chosen from the group comprising phosphate, pyrophosphate, hydrogenophosphate or polyphosphate anions, substituted if necessary by an alkali metal, and silicate.
A titre d'exemples de sels utilisables dans le cadre du présent procédé on peut citer :
- le phosphate de titane (α-TiP)
- le phosphate de zirconium (α-ZrP)
- le phosphate de cérium
- Ti(NaPO₄)₂
- TiNaH(PO₄)₂
- TiP₂O₇
- TaH (PO₄)₂
- NbOPO₄
- UO₂HPO₄
- Cr₅(P₃O₁₀)₃
- Fe₄(P₂O₇)₃
- les composés répondant à la formule
M1+x Zr₂ Six P3-x O₁₂
dans laquelle :- . M représente un atome de sodium ou de lithium
- . x est un nombre pouvant être nul et inférieur à 3
Ces précurseurs sont introduits sous forme de particules. Ils peuvent être introduits sous forme d'une poudre de granulométrie généralement inférieure à 500 µm ou sous forme de fibres dont les dimensions sont généralement comprises entre 0,1 et 50 µm pour le diamétre et entre 3 µm et 5 mm pour la longueur.Examples of salts which can be used in the context of the present process include:
- titanium phosphate (α-TiP)
- zirconium phosphate (α-ZrP)
- cerium phosphate
- Ti (NaPO₄) ₂
- TiNaH (PO₄) ₂
- TiP₂O₇
- TaH (PO₄) ₂
- NbOPO₄
- UO₂HPO₄
- Cr₅ (P₃O₁₀) ₃
- Fe₄ (P₂O₇) ₃
- the compounds corresponding to the formula
M 1 + x Zr₂ Si x P 3-x O₁₂
in which :- . M represents a sodium or lithium atom
- . x is a number that can be zero and less than 3
These precursors are introduced in the form of particles. They can be introduced in the form of a powder with a grain size generally less than 500 μm or in the form of fibers whose dimensions are generally between 0.1 and 50 μm for the diameter and between 3 μm and 5 mm for the length.
Le liant à base de polymère fluoré se présente généralement sous forme de poudre sèche ou de dispersion aqueuse (latex) dont l'extrait sec représente de 30 à 80 % en poids.The fluoropolymer-based binder is generally in the form of a dry powder or an aqueous dispersion (latex), the dry extract of which represents from 30 to 80% by weight.
Comme cela est bien connu de l'homme de l'art la dispersion ou suspension en cause est en général fortement diluée, la teneur en matières sèches (fibres, liant, précurseurs et additifs) représentant de l'ordre de 1 à 15 % du poids de l'ensemble pour en faciliter la manipulation à l'échelle industrielle.As is well known to those skilled in the art, the dispersion or suspension in question is generally highly diluted, the dry matter content (fibers, binder, precursors and additives) representing of the order of 1 to 15% of the weight of the assembly to facilitate handling on an industrial scale.
Divers additifs peuvent également être introduits dans la dispersion en particulier des agents tensio-actifs ou surfactifs tel l'octoxynol (Triton X-100®), des agents porogènes tel la silice, des agents épaississants tels des polysaccharides naturels ou synthétiques.Various additives can also be introduced into the dispersion, in particular surfactants or surfactants such as octoxynol (Triton X-100®), pore-forming agents such as silica, thickening agents such as natural or synthetic polysaccharides.
Bien entendu la dispersion renfermera tous les constituants essentiels du diaphragme à l'exception du gel d'oxohydroxyde dont il a été question précédemment, mais des précurseurs du gel au sens indiqué ci-avant seront présents.Of course, the dispersion will contain all the essential constituents of the diaphragm with the exception of the oxohydroxide gel which was discussed above, but gel precursors in the sense indicated above will be present.
Les quantités relatives des constituants essentiels du diaphragme à introduire dans la dispersion sont aisément déterminables par l'homme de l'art compte-tenu du fait qu'elles sont sensiblement les mêmes que celles retrouvées dans le diaphragme lui-même, aux exceptions près du porogène qui est en principe éliminé par action, par exemple, de la soude électrolytique et du précurseur du gel d'oxohydroxyde. En effet le précurseur est transformé totalement en gel d'oxohydroxyde dont la partie "active", obtenue après lavage et séchage du gel, représente de 10 à 90 % en poids du précurseur introduit.The relative amounts of the essential constituents of the diaphragm to be introduced into the dispersion are readily determinable by those skilled in the art, given that they are substantially the same as those found in the diaphragm itself, with the exceptions of the pore-forming agent which is in principle eliminated by the action, for example, of electrolytic soda and of the precursor of oxohydroxide gel. In fact, the precursor is completely transformed into an oxohydroxide gel, the "active" part of which, obtained after washing and drying the gel, represents from 10 to 90% by weight of the precursor introduced.
L'homme de l'art sera également à même de déterminer au moyen d'essais simples la quantité de matières sèches à disperser dans le milieu aqueux en fonction du taux d'arrêt observable sur le matériau poreux au travers duquel la dispersion est filtrée dans les conditions de vide programmé.Those skilled in the art will also be able to determine by means of simple tests the amount of dry matter to be dispersed in the aqueous medium as a function of the rate of arrest observable on the porous material through which the dispersion is filtered in programmed vacuum conditions.
En général, l'extrait sec en suspension renferme comme constituants principaux :
- de 30 à 80 % en poids de libres
- de 1 à 50 % en poids d'au moins un précurseur de gel d'oxohydroxyde
- de 5 à 35 % en poids de poudre de PTFE (liant) et,
- de 5 à 40 % en poids de silice.
- from 30 to 80% by weight of free
- from 1 to 50% by weight of at least one oxohydroxide gel precursor
- from 5 to 35% by weight of PTFE powder (binder) and,
- from 5 to 40% by weight of silica.
Pour une bonne mise en oeuvre de la présente invention la teneur en poudre de PTFE représente de 5 à 40 % en poids de l'ensemble (poudre de PTFE + fibres). Pour une bonne mise en oeuvre de la présente invention la teneur en poids d'au moins un précurseur de gel d'oxohydroxyde dans ledit extrait sec sera comprise entre 5 et 40 %.For a good implementation of the present invention the content of PTFE powder represents from 5 to 40% by weight of the whole (PTFE powder + fibers). For a good implementation of the present invention the content by weight of at least one oxohydroxide gel precursor in said dry extract will be between 5 and 40%.
La nappe est alors formée par filtration sous vide programmé, de la dispersion à travers un matériau poreux telles des toiles ou des grilles dont le vide de maille, les perforations ou la porosité peut-être compris entre 1 µm et 2 mm.The sheet is then formed by filtration under programmed vacuum, dispersion through a porous material such as fabrics or grids whose mesh vacuum, perforations or porosity may be between 1 µm and 2 mm.
Le programme de vide peut être continu ou par paliers, de la pression atmosphérique à la pression finale (0,01 à 0,5 bar absolu).The vacuum program can be continuous or in stages, from atmospheric pressure to final pressure (0.01 to 0.5 bar absolute).
Après élimination du milieu liquide et, le cas échéant le séchage de la nappe ainsi formée, l'ensemble est fritté.After elimination of the liquid medium and, if necessary the drying of the sheet thus formed, the assembly is sintered.
Le frittage est réalisé de manière en elle-même connue à une température supérieure au point de fusion ou de ramollissement du polymère fluoré, liant de ladite nappe. Cette étape qui permet la consolidation de la nappe, est alors suivie d'une étape de traitement par lequel la nappe est mise en contact avec une solution aqueuse d'hydroxyde alcalin, et plus particulièrement avec une solution de soude électrolytique.Sintering is carried out in a manner known per se at a temperature above the melting or softening point of the fluoropolymer, binder of said sheet. This step which allows the consolidation of the sheet, is then followed by a treatment step by which the sheet is brought into contact with an aqueous solution of alkali hydroxide, and more particularly with an electrolytic soda solution.
Cette mise en contact peut être réalisée in-situ c'est-à-dire lors de la mise en place de la nappe consolidée dans la cellule d'électrolyse, au contact de la solution de soude électrolytique.This contacting can be carried out in situ, that is to say during the positioning of the consolidated sheet in the electrolysis cell, in contact with the electrolytic soda solution.
Le traitement est avantageusement réalisé au contact d'une solution aqueuse d'hydroxyde de sodium dont la concentration est comprise entre 40 et 200 g/l et à une température comprise entre 20 et 95°C.The treatment is advantageously carried out in contact with an aqueous sodium hydroxide solution whose concentration is between 40 and 200 g / l and at a temperature between 20 and 95 ° C.
Les précurseurs du gel d'oxohydroxyde, définis précédemment sont susceptibles de subir diverses transformations au cours des diverses opérations d'élaboration du diaphragme, et notamment une transformation non destructive lors de l'opération de frittage, c'est-à-dire conduisant uniquement à des pertes de molécules d'eau d'hydratation ou de constitution ; ils seront transformés par l'étape de traitement précitée en un gel frais d'oxohydroxyde du métal concerné, imprégné d'électrolyte et d'eau.The precursors of the oxohydroxide gel, defined above, are capable of undergoing various transformations during the various operations for producing the diaphragm, and in particular a non-destructive transformation during the sintering operation, that is to say only leading loss of hydration or constitution water molecules; they will be transformed by the above-mentioned treatment step into a fresh gel of oxohydroxide of the metal concerned, impregnated with electrolyte and water.
Les propriétés d'un tel diaphragme sont notablement améliorées.The properties of such a diaphragm are significantly improved.
Par ailleurs le recours à des précurseurs sous forme de poudre facilite grandement la mise en oeuvre.Furthermore, the use of precursors in powder form greatly facilitates implementation.
Selon une variante avantageuse de mise en oeuvre du présent procédé la filtration de la dispersion ou suspension est réalisée à travers un élément cathodique (ou précathodique) au sens indiqué dans le présent mémoire.According to an advantageous variant of the implementation of the present process, the filtration of the dispersion or suspension is carried out through a cathode (or precathode) element in the sense indicated in the present specification.
Par la mise en oeuvre d'une telle variante il est possible de réaliser une association diaphragme - élément précathodique.By implementing such a variant it is possible to make a diaphragm - precathode element association.
Une telle association, présente des propriétés remarquables de cohérence, couplant les avantages procurés par l'élément précathodique et les diaphragmes selon l'invention.Such an association has remarkable coherence properties, coupling the advantages provided by the precathode element and the diaphragms according to the invention.
L'invention a également pour objet un procédé de préparation de telles associations comprenant essentiellement la succession d'étapes suivantes :
- a) le dépôt d'une nappe précathodique par filtration sous vide programmé d'une dispersion en milieu essentiellement aqueux de fibres, de liant sous forme de particules et, le cas échéant d'additifs, à travers une cathode élémentaire constituée d'une surface métallique présentant un vide de maille ou des perforations compris entre 20 µm et 5 mm,
- b) l'élimitation du milieu liquide et, le cas échéant, le séchage de la nappe ainsi formée,
- c) la filtration sous vide programmé, à travers la nappe précathodique, d'une dispersion en milieu essentiellement aqueux de fibres, de liant à base d'un polymère fluoré sous forme de particules, au moins un précurseur d'oxohydroxyde de l'un au moins des métaux des groupes IVA, IVB, VB et VIB de la classification périodique ou des séries des lanthanides et des actinides, ou le fer, sous forme de particules, et, le cas échéant des additifs,
- d) l'élimination du milieu liquide et, le cas échéant, le séchage de la nappe ainsi formée;
- e) le frittage de l'ensemble et,
- f) le traitement, le cas échéant in-situ dans les conditions de l'électrolyse, par une solution aqueuse d'hydroxyde alcalin.
- a) the deposition of a precathode layer by programmed vacuum filtration of a dispersion in an essentially aqueous medium of fibers, of binder in the form of particles and, where appropriate of additives, through an elementary cathode constituted by a surface metallic with a mesh void or perforations between 20 µm and 5 mm,
- b) the elimination of the liquid medium and, if necessary, the drying of the sheet thus formed,
- c) filtration under programmed vacuum, through the precathode layer, of a dispersion in an essentially aqueous medium of fibers, of binder based on a fluoropolymer in the form of particles, at least one oxohydroxide precursor of at least one of the metals of groups IVA, IVB, VB and VIB of the periodic table or of the lanthanide and actinide series , or iron, in the form of particles, and, where appropriate, additives,
- d) eliminating the liquid medium and, if necessary, drying the sheet thus formed;
- e) sintering the assembly and,
- f) treatment, if necessary in situ under the conditions of electrolysis, with an aqueous solution of alkali hydroxide.
Un tel procédé présente l'avantage de contribuer à l'élaboration d'associations de forte cohésion. Un autre avantage réside dans sa grande simplicité de mise en oeuvre du fait qu'une seule étape de frittage est suffisante pour élaborer des associations de forte cohésion et du fait qu'une seule étape permet d'éliminer les porogènes, tant de la nappe précathodique que du diaphragme, et de donner naissance au gai frais d'oxohydroxyde du métal en cause.Such a method has the advantage of contributing to the development of associations of strong cohesion. Another advantage resides in its great simplicity of implementation of the fact that a single sintering step is sufficient to develop associations of strong cohesion and of the fact that a single step makes it possible to eliminate the porogens, both from the precathode layer. than the diaphragm, and to give birth to the fresh gay oxohydroxide of the metal in question.
Selon une variante avantageuse dudit procédé on utilise comme liant de la nappe précathodique et du diaphragme, du PTFE.According to an advantageous variant of said process, PTFE is used as binder of the precathode layer and of the diaphragm.
Les exemples ci-après illustrent la présente invention.The following examples illustrate the present invention.
On prépare une suspension sous agitation de :
- A - eau adoucie, dont la quantité est calculée pour obtenir environ 4 litres de suspension
- B - 100 g de fibres d'amiante chrysotile de diamètre 20 nm (200 Angström) et de moins d'1 mm de longueur.
- C - 1,2 g d'octoxynol sous forme d'une solution dans l'eau à 40 g/l.
On agite 30 mn puis on ajoute successivement les divers ingrédients suivants sous agitation : - D - 25 g de PTFE sous forme de latex à environ 65 % en poids d'extrait sec
- E - 30 g de silice précipitée sous forme de particules de granulométrie moyenne de 3 µm et dont la surface B.E.T. est de 250 m²/g.
- F - X g de poudre de phosphate de titane (α-TiP), de phosphate de zirconium (α-ZrP) ou de phosphate de cérium (CeP).
- G - 1,5 g de gomme xanthane.
On agite durant 30 mn.
- A - softened water, the amount of which is calculated to obtain approximately 4 liters of suspension
- B - 100 g of chrysotile asbestos fibers with a diameter of 20 nm (200 Angström) and less than 1 mm in length.
- C - 1.2 g of octoxynol in the form of a solution in water at 40 g / l.
The mixture is stirred for 30 min and then the following various ingredients are successively added with stirring: - D - 25 g of PTFE in the form of latex at around 65% by weight of dry extract
- E - 30 g of silica precipitated in the form of particles with an average particle size of 3 μm and whose BET surface area is 250 m² / g.
- F - X g of titanium phosphate powder (α-TiP), zirconium phosphate (α-ZrP) or cerium phosphate (CeP).
- G - 1.5 g of xanthan gum.
The mixture is stirred for 30 min.
Le volume total d'eau est calculé de manière à ce que le pourcentage pondéral de matière sèche (B + D + E + F)/A soit d'environ 4,5 %.The total volume of water is calculated so that the weight percentage of dry matter (B + D + E + F) / A is approximately 4.5%.
On abandonne la solution pendant 48 heures
On prélève le volume de solution requis de manière à ce qu'il contienne la quantité d'extrait sec que l'on compte déposer pour former le diaphragme (de l'ordre de 1,3 kg/m2).The solution is left for 48 hours
The volume of solution required is withdrawn so that it contains the quantity of dry extract which it is intended to deposit to form the diaphragm (of the order of 1.3 kg / m2).
La suspension est réagitée pendant 30 mn avant utilisation.The suspension is reacted for 30 min before use.
La filtration est conduite sous vide programmé sur cathode volumique (préparée au préalable selon l'exemple 7 de la demande de brevet européen n° 296 076) comme suit :
- . 1 mn à un vide -5 à -10 mbar de pression relative par rapport à la pression atmosphérique
- . montée du vide à raison de 50 mbar/mn
- . essorage de 15 mn au vide maximum (environ -800 mbar de pression relative par rapport à la pression atmosphérique)
- . 1 min at vacuum -5 to -10 mbar relative pressure compared to atmospheric pressure
- . vacuum rise at 50 mbar / min
- . spin for 15 min at maximum vacuum (approximately -800 mbar of relative pressure compared to atmospheric pressure)
On a alors évalué les performances des divers matériaux composites, dont la fabrication vient d'être décrite, dans une cellule d'électrolyse qui présente les caractéristiques suivantes et dont les conditions de fonctionnement sont indiquées ci-après :
- . Anode en titane déployé, laminé, revêtu de TiO₂-RuO₂
- . élément cathodique en acier doux tressé et laminé ; fils de 2 mm, maille de 2 mm recouvert de la nappe précathodique et du diaphragme.
- . Distance anode-élément cathodique : 6 mm
- . Surface active de l'électrolyseur : 0,5 dm²
- . Cellule assemblée selon le type filtre-presse
- . Densité de courant : 25 A dm⁻²
- . Température : 85°C
- . Fonctionnement à chlorure anodique constant : 4,8 mole.1⁻¹
- . Titre de la soude électrolytique : 120 ou 200 g/l
- . RF : rendement Faraday
- . ΔU : tension aux bornes de l'électrolyseur sous la densité de courant spécifiée.
- . performance (kwh/TCl₂) = consommation énergétique du système en kilowattheure par tonne de chlore produit.
- . Expanded titanium anode, laminated, coated with TiO₂-RuO₂
- . cathode element in braided and rolled mild steel; 2 mm wire, 2 mm mesh covered with the precathode layer and the diaphragm.
- . Distance anode-cathode element: 6 mm
- . Active surface area of the chlorinator: 0.5 dm²
- . Cell assembled according to the filter press type
- . Current density: 25 A dm⁻²
- . Temperature: 85 ° C
- . Operation with constant anodic chloride: 4.8 mole.1⁻¹
- . Title of electrolytic soda: 120 or 200 g / l
- . RF: Faraday yield
- . ΔU: voltage across the electrolyser at the specified current density.
- . performance (kwh / TCl₂) = energy consumption of the system in kilowatt hours per tonne of chlorine produced.
Claims (18)
- A microporous diaphragm which can be formed in situ by a wet process, comprising a fibrous coating containing asbestos whose fibres are microconsolidated by a fluoropolymer, the assembly being sintered, said coating essentially comprising:- 3 % to 35 % by weight of fluoropolymer binding the fibres,- 1 % to 50 % by weight of an oxohydroxide gel of at least one metal from groups IVA, IVB, VB and VIB of the periodic classification, the lanthanide series, the actinide series, or iron,- 20 % to 95 % by weight of fibres, the asbestos fibres representing at least 1 % by weight of said fibres.
- Diaphragm according to claim 1, characterised in that the asbestos fibres constitute at least 40 % by weight of the total amount of fibres.
- Diaphragm according to claim 1 or claim 2, characterised in that it contains an oxohydroxide gel of at least one metal from groups IVA and IVB.
- Diaphragm according to claim 1 or claim 2, characterised in that it contains an oxohydroxide gel of titanium, zirconium or cerium.
- Diaphragm according to any one of the preceding claims, characterised in that the fluoropolymer binding the fibres is polytetrafluoroethylene.
- Diaphragm according to any one of the preceding claims, characterised in that the binder constitutes 5 % to 40 % by weight of the sub assembly (fibres + binder).
- Diaphragm according to any one of the preceding claims, characterised in that the proportion of oxohydroxide gel is between 1 % and 25 % by weight.
- Diaphragm according to any one of the preceding claims, characterized in that the proportion of oxohydroxide gel is greater than 3 % by weight.
- Combination of a composite cathode element and a diaphragm in accordance with any one of the preceding claims.
- Combination according to claim 9, characterised in that the cathode element results from the combination of a cathode element constituted by a highly porous metallic surface and a fibrous microporous coating containing a high proportion of electrically conducting fibres, the fibres being microconsolidated by a fluoropolymer.
- Combination according to claim 10, characterised in that the composite cathode element contains carbon or graphite fibres with a monodispersed length distribution as the electrically conducting fibres.
- Combination according to claim 10 or claim 11,, characterized in that the fluoropolymer constituting the fibre binder for both the diaphragm and the precathode coating is polytetrafluoroethylene.
- Process for the preparation of a diaphragm according to any one of claims 1 to 8, characterised in that it essentially comprises the following sequence of steps:a) preparing, in essentially aqueous medium, a dispersion comprising fibres, a fluoropolymer binder in particle form, at least one oxohydroxide precursor of at least one metal from groups IVA, IVB, VB and VIB of the periodic classification, the lanthanide or actinide series, or iron, in particle form and, optionally, additives,b) depositing a coating by programmed vacuum filtration of said dispersion through a porous material,c) eliminating the liquid medium and, optionally, drying the coating formed,d) sintering the coating and,e) treating with an aqueous solution of an alkali hydroxide, optionally in situ under electrolysis conditions.
- Process for the preparation of an combination in accordance with any one of claims 9 to 12, characterised in that it essentially comprises the following sequence of steps:a) depositing a precathode coating by programmed vacuum filtration of an essentially aqueous dispersion of fibres, a binder in particle form and, optionally, additives, through a cathode element constituted by a metallic surface having a mesh size or perforations of between 20 µm and 5 mm,b) eliminating the liquid medium and, optionally, drying the coating formed,c) programmed vacuum filtration through the precathode coating of an essentially aqueous dispersion of fibres, a fluoropolymer based binder in particle form, at least one oxohydroxide precursor of at least one metal from groups IVA, IVB, VB and VIB of the periodic classification, the lanthanide and actinide series or iron, in particle form and, optionally, additives,d) eliminating the liquid medium and, optionally, drying the coating thus formed,e) sintering the assembly and,f) treating with an aqueous alkaline hydroxide solution, optionally in situ under electrolysis conditions.
- Process according to any one of claims 13 or 14, characterised in that the oxohydroxide precursor is selected from salts of metals from groups IVA, IVB, VB and VIB of the periodic classification, the lanthanide and actinide series or iron, which are as insoluble as possible in water, where the anion is selected from phosphate, pyrophosphate, hydrogenophosphate or polyphosphate anions, optionally substituted by an alkali metal, and silicate anions.
- Process according to claim 15, characterised in that the precursor is α-TiP, α-ErP or CeP.
- Process according to any one of claims 13 to 16, characterised in that the suspension for depositing on the diaphragm comprises the following principal constituents as dry matter:- 30 % to 80 % by weight of fibres,- 1 % to 50 % by weight of at least one oxohydroxide gel precursor,- 5 % to 35 % by weight of PTFE powder (binder), and- 5 % to 40 % by weight of silica.
- Process according to any one of claims 14 to 17, characterised in that the binder for the precathode coating and the diaphragm is polytetrafluoroethylene.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
FR8910937 | 1989-08-10 | ||
FR8910937A FR2650842B1 (en) | 1989-08-10 | 1989-08-10 | IMPROVEMENT OF A DIAPHRAGM COMPRISING ASBESTOS FIBERS, ASSOCIATION OF SUCH A DIAPHRAGM WITH A CATHODE ELEMENT AND PROCESS FOR OBTAINING THE SAME |
Publications (2)
Publication Number | Publication Date |
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EP0412916A1 EP0412916A1 (en) | 1991-02-13 |
EP0412916B1 true EP0412916B1 (en) | 1994-12-07 |
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Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP90420362A Expired - Lifetime EP0412916B1 (en) | 1989-08-10 | 1990-07-31 | Diaphragm comprising asbestos fibres, association of such a diaphragm with a cathodic element and process of manufacture |
Country Status (15)
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US (2) | US5092977A (en) |
EP (1) | EP0412916B1 (en) |
JP (1) | JPH0653942B2 (en) |
KR (1) | KR0126912B1 (en) |
CN (1) | CN1049385A (en) |
AT (1) | ATE115199T1 (en) |
AU (1) | AU627917B2 (en) |
BR (1) | BR9003917A (en) |
CA (1) | CA2023031A1 (en) |
DD (1) | DD297192A5 (en) |
DE (1) | DE69014764T2 (en) |
ES (1) | ES2067712T3 (en) |
FR (1) | FR2650842B1 (en) |
GR (1) | GR3015218T3 (en) |
RU (1) | RU2070232C1 (en) |
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US5246559A (en) * | 1991-11-29 | 1993-09-21 | Eltech Systems Corporation | Electrolytic cell apparatus |
FR2703075B1 (en) * | 1993-03-26 | 1995-06-16 | Rhone Poulenc Chimie | PROCESS FOR THE PREPARATION OF MICROPOROUS DIAPHRAGM. |
US6296745B1 (en) | 2000-04-28 | 2001-10-02 | Ppg Industries Ohio, Inc. | Method of operating chlor-alkali electrolytic cells |
ITMI20072271A1 (en) * | 2007-12-04 | 2009-06-05 | Industrie De Nora Spa | SEPARATOR FOR CHLORINE-ALCALE ELECTROLYTIC CELLS AND METHOD FOR ITS MANUFACTURE |
KR101648379B1 (en) * | 2016-01-12 | 2016-08-16 | 재단법인 한국탄소융합기술원 | Carbon fiber non woven fabric and manufacturing method thereof and using method using it |
KR102501471B1 (en) * | 2018-01-16 | 2023-02-20 | 삼성전자주식회사 | Porous film, Separator comprising porous film, Electrochemical device comprising porous film, and Method for preparing porous film |
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ZA74315B (en) * | 1973-01-17 | 1975-03-26 | Diamond Shamrock Corp | Dimensionally stable asbestos diaphragms |
US4701250A (en) * | 1973-01-17 | 1987-10-20 | Eltech Systems Corporation | Dimensionally stable asbestos diaphragm coated foraminous cathode |
FR2229739B1 (en) * | 1973-05-18 | 1976-09-17 | Rhone Progil | |
JPS51121483A (en) * | 1975-04-18 | 1976-10-23 | Asahi Glass Co Ltd | Improved asbestos diaphragms |
US4105516A (en) * | 1977-07-11 | 1978-08-08 | Ppg Industries, Inc. | Method of electrolysis |
US4210744A (en) * | 1978-12-11 | 1980-07-01 | Ciba-Geigy Corporation | Adducts containing epoxide groups, from hydantoin trisepoxides and binuclear hydantoins |
JPS5739823A (en) * | 1980-08-21 | 1982-03-05 | Tokyo Electric Co Ltd | Electric cleaner |
US4354900A (en) * | 1980-12-01 | 1982-10-19 | Diamond Shamrock Corporation | Strengthened fiberous electrochemical cell diaphragm and a method for making |
CA1189668A (en) * | 1981-09-08 | 1985-07-02 | Ares N. Theodore | PROCESS FOR MOLDING COMPLEX .beta."-ALUMINA SHAPES FOR SODIUM/SULFUR BATTERIES |
US4447566A (en) * | 1983-01-27 | 1984-05-08 | Eltech Systems Corp. | Modified liquid permeable asbestos diaphragms with improved dimensional stability |
US4665120A (en) * | 1983-01-27 | 1987-05-12 | Eltech Systems Corporation | Modified liquid permeable asbestos diaphragms with improved dimensional stability |
US4563260A (en) * | 1983-01-27 | 1986-01-07 | Eltech Systems Corporation | Modified liquid permeable asbestos diaphragms with improved dimensional stability |
EP0132425A1 (en) * | 1983-06-22 | 1985-01-30 | Elf Atochem S.A. | Material based on conductive fibres, its manufacture and its use, in particular in the production of cathode elements |
FR2585623B1 (en) * | 1985-08-02 | 1988-02-12 | Rhone Poulenc Chim Base | MICROPOROUS CONSOLIDATED MATERIAL, PROCESS FOR OBTAINING SAME AND APPLICATIONS IN PARTICULAR FOR THE PRODUCTION OF CATHODIC ELEMENTS |
JPS6244989A (en) * | 1985-08-22 | 1987-02-26 | 日本電気株式会社 | Thin film el element |
FR2589787B1 (en) * | 1985-09-27 | 1988-05-20 | Rhone Poulenc Chim Base | MICROPOROUS MATERIAL, PROCESS FOR OBTAINING SAME, AND APPLICATIONS IN PARTICULAR FOR THE PRODUCTION OF CATHODE ELEMENTS |
US4720334A (en) * | 1986-11-04 | 1988-01-19 | Ppg Industries, Inc. | Diaphragm for electrolytic cell |
US4810345A (en) * | 1986-12-15 | 1989-03-07 | Oxytech Systems, Inc. | Diaphragm for an electrolytic cell |
FR2616809B1 (en) * | 1987-06-19 | 1991-06-14 | Rhone Poulenc Chimie | ELECTROACTIVE MATERIAL BASED ON CONDUCTIVE FIBERS, ITS MANUFACTURE AND ITS USE FOR MAKING CATHODIC ELEMENTS |
-
1989
- 1989-08-10 FR FR8910937A patent/FR2650842B1/en not_active Expired - Lifetime
-
1990
- 1990-07-31 DE DE69014764T patent/DE69014764T2/en not_active Expired - Fee Related
- 1990-07-31 EP EP90420362A patent/EP0412916B1/en not_active Expired - Lifetime
- 1990-07-31 ES ES90420362T patent/ES2067712T3/en not_active Expired - Lifetime
- 1990-07-31 AT AT90420362T patent/ATE115199T1/en not_active IP Right Cessation
- 1990-08-07 AU AU60263/90A patent/AU627917B2/en not_active Ceased
- 1990-08-08 CN CN90106756A patent/CN1049385A/en active Pending
- 1990-08-09 RU SU904831026A patent/RU2070232C1/en active
- 1990-08-09 JP JP2213594A patent/JPH0653942B2/en not_active Expired - Lifetime
- 1990-08-09 CA CA002023031A patent/CA2023031A1/en not_active Abandoned
- 1990-08-09 DD DD90343360A patent/DD297192A5/en not_active IP Right Cessation
- 1990-08-09 BR BR909003917A patent/BR9003917A/en not_active Application Discontinuation
- 1990-08-10 US US07/565,344 patent/US5092977A/en not_active Expired - Fee Related
- 1990-08-10 KR KR1019900012312A patent/KR0126912B1/en not_active IP Right Cessation
-
1991
- 1991-12-04 US US07/802,319 patent/US5320867A/en not_active Expired - Fee Related
-
1995
- 1995-02-28 GR GR950400422T patent/GR3015218T3/en unknown
Also Published As
Publication number | Publication date |
---|---|
CA2023031A1 (en) | 1991-02-11 |
ATE115199T1 (en) | 1994-12-15 |
US5320867A (en) | 1994-06-14 |
DD297192A5 (en) | 1992-01-02 |
KR910004876A (en) | 1991-03-29 |
GR3015218T3 (en) | 1995-05-31 |
DE69014764D1 (en) | 1995-01-19 |
CN1049385A (en) | 1991-02-20 |
FR2650842A1 (en) | 1991-02-15 |
EP0412916A1 (en) | 1991-02-13 |
AU6026390A (en) | 1991-02-14 |
RU2070232C1 (en) | 1996-12-10 |
JPH0653942B2 (en) | 1994-07-20 |
KR0126912B1 (en) | 1998-04-06 |
AU627917B2 (en) | 1992-09-03 |
BR9003917A (en) | 1991-09-03 |
ES2067712T3 (en) | 1995-04-01 |
JPH03107491A (en) | 1991-05-07 |
US5092977A (en) | 1992-03-03 |
FR2650842B1 (en) | 1992-01-17 |
DE69014764T2 (en) | 1995-05-18 |
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