US3663406A - Combined electrodialysis and ultrafiltration of an electrodeposition bath - Google Patents

Combined electrodialysis and ultrafiltration of an electrodeposition bath Download PDF

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US3663406A
US3663406A US3663406DA US3663406A US 3663406 A US3663406 A US 3663406A US 3663406D A US3663406D A US 3663406DA US 3663406 A US3663406 A US 3663406A
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membrane
electrodialysis
bath
ultrafiltration
composition
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Louis R Le Bras
Robert R Zwack
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PPG Industries Inc
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PPG Industries Inc
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/58—Multistep processes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14—Ultrafiltration; Microfiltration
    • B01D61/18—Apparatus therefor
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/22—Servicing or operating apparatus or multistep processes
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D13/00—Electrophoretic coating characterised by the process
    • C25D13/22—Servicing or operating apparatus or multistep processes
    • C25D13/24—Regeneration of process liquids
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/02—Reverse osmosis; Hyperfiltration ; Nanofiltration
    • B01D61/025—Reverse osmosis; Hyperfiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/14—Ultrafiltration; Microfiltration
    • B01D61/145—Ultrafiltration
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
    • B01D61/42—Electrodialysis; Electro-osmosis ; Electro-ultrafiltration; Membrane capacitive deionization
    • B01D61/44—Ion-selective electrodialysis
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/249921—Web or sheet containing structurally defined element or component
    • Y10T428/249953—Composite having voids in a component [e.g., porous, cellular, etc.]
    • Y10T428/249975—Void shape specified [e.g., crushed, flat, round, etc.]
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/8305—Miscellaneous [e.g., treated surfaces, etc.]

Definitions

  • Electrodeposition has recently received wide industrial acceptance as a method for applying protective and decorative coatings.
  • the process of electrodepositing is well described in the art.
  • an aqueous bath containing depositable coating composition is placed in contact with an electrically-conductive anode and an electricallyconductive cathode, and upon the passage of electric current (usually direct current) between the anode and cathode while in contact with the bath containing the coating composition, an adherent film of the coating composition is deposited, either on the anode or the cathode, depending upon thetype of resin employed.
  • the electrodeposition process parameters used vary widely.
  • the voltage applied may vary from as low as, for example, one volt, or as high as, for example, 500 volts or higher.
  • the voltage used ranges from 50 to 400 volts.
  • the current demands are higher during the initial stage of the deposition process, but decrease as the deposited film insulates the particular conductive electrode.
  • the electrode employed may be any electrically-conductive surface, such as iron, steel, aluminum, zinc, copper, chromium, magnesium, galvanized steel, phosphatized steel, as well as other metals and pretreated metals.
  • paper or other non-conductive materials can be coated or be impregnated with conductive substances and utilized as the electrode on which electrodepositable compositions are deposited.
  • a wide variety of electrodepositable resins are known in the art.
  • a number of water-soluble, waterdispersible, or water-emulsifiable polycarboxylic acid resins can be electrodeposited.
  • Some of these resins include: reaction products or adducts of a drying oil or semidrying oil fatty acid with a dicarboxylic acid or anhydride; interpolymers of a hydroxyalkyl ester of an unsaturated carboxylic acid and an unsaturated monomer; alkydamine vehicles; that is, vehicles containing an alkyd resin and an amine-aldehyde resin; and mixed esters of resinous polyols.
  • the electrodepositability of various other materials including a number of waxes and natural and synthetic resins, are also known in the art.
  • Electrodialysis while effective in removing counter-ions (ions of the opposite charge), does not remove other ions, many of which are highly undesirable, and does not remove other, uncharged low molecular weight species. Moreover, ions with slow diffusion rates or slow ion mobility may not be removed by electrodialysis at a rate which will enable optimum control of the operating parameter, and in some instances ions having a charge opposite to those ions sought to be removed by electrodialysis process will remain in the electrodepositable composition producing deleterious effects on the coating parameters and deposited coating. Ultrafiltration, on the other hand, removes all materials below a certain molecular size and when used sufficiently to remove all undesirable components tends also to remove some desirable ones.
  • electrodepositable compositions that are not readily susceptible to complete control by either electrodialysis or ultrafiltration can be efficiently controlled by employing a combination of electrodialysis and a selective separation process such as ultrafiltration.
  • a selective separation process such as ultrafiltration.
  • dialysis is the separation of solutes by means of their unequal diffusion rate through membranes, while in electrodialysis the passage of electrolyte through the membranes is accelerated by an electromoti e force.
  • the membranes employed in electrodialysis are frequently referred to as semi-permeable membranes and include various components which are interposed between two bodies of liquid so as to prevent their gross inter-mixture 'but which permit the passage of solvent and at least one of several solutes from one body of liquid to the other.
  • Electrodialysis is controlled by electromotive force, diffusion rate and the membrane properties.
  • the electromotive force may be the same as that used in the electrodeposition process, however, in many instances a different electromotive force is desirable.
  • Diffusion is the force that drives the molecules and ions toward and when possible across the membranes.
  • the nature of the membrane determines which molecular species can pass and which are held back. Thus, preparation and selection of suitable membranes is of particular importance.
  • a variety of membranes may be employed in the electrodialysis as used in the present invention.
  • dialysis membranes such as regenerated cellulose on fabrics or felts; films of polyvinyl compounds as well as membrane materials which are not usually considered as dialysis membranes, but which produce the desired electrodialysis when employed in the electrodeposition process.
  • useful membranes are those comprised of woven or unwoven cloth, including cloth of various natural or synthetic fibers.
  • Other membranes such as cloth treated with re-agents that dissolve cellulose-ammoniacal cupric salt solution or NaOH and carbon disulfide; protein for insolubilized gelatin-soybean protein and animal skin; inorganic membranes from precipitated silica; and ion-exchange membranes are also useful.
  • Positively-charged membranes are selective to anions and impervious to cations, while negatively-charged membranes are selective to cations and impervious to anions.
  • the choice of membrane depends in part upon the type of electrodepositable composition treated.
  • the preferred membranes for use in the electrodialysis step of the invention are those made of a plain Woven cloth comprising plant fibers, and selectively permeable ion-exchange membranes.
  • the membranes comprising plant fibers are advantageous in that they have good durability for industrial use and the investment expense is low, while still having a remarkable degree of selectivity in their permeation characteristics.
  • the plant fibers of the membrane may be fruit fibers, for example, coconut and the like; the fibers may be leaf fibers, for example, Manila hemp, New Zealand flax and the like; the fibers may be vegetable fibers, for example, seed fibers such as cottonseed and the like; and the fibers may be phloem fibers such as flax, linen, hemp, China grass, ramie, jute and the like.
  • the plant fiber membranes need not necessarily be constructed of natural fibers, for example, synthetic fibers having high tensile strength may readily be interwoven with the plant fibers, thus adding strength and durability to the membrane.
  • synthetic fibers having high tensile strength may readily be interwoven with the plant fibers, thus adding strength and durability to the membrane.
  • the fibers When a plant fiber membrane is immersed in an electrodepositable composition, the fibers generally swell in a direction that is perpendicular to the lengths of the fibers so that the swollen fibers produce a closely woven cloth, thus the pigment and vehicle portions of the electrodepositable composition are not readily passable through the cloth under such conditions.
  • the plant fibers show a negative charge and thus are readily employed as an electrolytically negative diaphragm, that is, a diaphragm membrane that is permeable to cations and impervious to anions.
  • Selectively permeable ion exchange membranes are also desirably employed in a manner similar to that of the plant fiber membranes.
  • Using an ion-exchange membrane has advantages over using an unselective dialysis mem brane to separate accumulated ions from the depositable compositions, in that the ion-exchange membranes normally have a lower electrical resistance than dialysis membranes, and thus being selective, provide for better control of the pH in the coating bath. Controlling the pH is of particular importance when the coating composition is in use, for in such case, the ion selective membrane permits a faster and more efficient passage of ions of opposite charge through it.
  • the resistivity of the receiving solvent, in contact with the electrode and confined by the membrane can readily be reduced by the addition of a suitable ionizable material, such as soda ash, ammonium sulphate, sodium sulphate and sodium bicarbonate, without risk of contamination of the coating composition.
  • a suitable ionizable material such as soda ash, ammonium sulphate, sodium sulphate and sodium bicarbonate, without risk of contamination of the coating composition.
  • KOH solutions or amide solutions are used.
  • the ion-exchange membranes employed in this invention may be prepared by the incorporation of finely divided ion-exchange resins in inert polymer matrices.
  • resins are fine beads of sulphonated crosslinked'polystyrene in polyethylene, films produced from styreneldivinyl benzene copolymers, when subjected to such treatments as sulphonation to yield cation-exchanges or chloromethylation and amination to yield anion-exchangers, and films of graft copolymers comprising an inert backbone and a reactive grafted component such as styrene.
  • the ion-exchange membranes employed generally have a pore size of less than 20A, for example, about 10 to 15A.
  • the fixed ion concentration of the membrane is usually at least one unit on the molarity scale, so that if the external concentration is not very high, they conduct almost exclusively by the migration of counter-ions.
  • Typical ion-exchange membranes have sodium ion transport numbers of at least 0.8 or greater, in sodium chloride solutions of IM concentration.
  • anodic or anionic coating composition When an anodic or anionic coating composition is employed, the negatively-charged vehicle will migrate under an electromotive force to the anode where the solubilizing agent is released, and thus positive-charged cations will migrate through the membrane.
  • a cathodic or cationic coating composition For example, if potassium hydroxide is utilized as a solubilizing agent in formulation of a depositable composition, the potassium ion released during the electrocoating process, and which tends to accumulate in the anode compartment, is removed by passage into a cathode compartment which is separated from the aqueous electrodepositable composition in the anode compartment by the membrane.
  • an acid-solubilized cationic resin such as an amine-terminated polyamide or acrylic polymer is used, the acidic agent tends to accumulate in the anode compartment and is removed in a similar manner.
  • the electrode compartment used in electrodialysis to separate the anode or cathode from the electrodepositable composition can be of any convenient shape.
  • Perforated cylindrical-shaped plastic containers having the membrane mounted on such super-structure and the electrode encased therein have been employed.
  • more commonly utilized structures are rectangular-shaped boxes having the electrode centrally located and the major walls of the said box parallel to the electrode and comprised of the membrane.
  • the electrode compartment is equipped with an input and outlet connections to facilitate flushing the compartment.
  • the electrode compartment may contain a receiving solvent (electrolyte) comprised of the aqueous depositable composition, but it is preferable to employ water in the electrode compartment, and, in particular, deionized water containing a minimum level of the electrolyte that is being removed.
  • means for periodic or continuous flushing of the electrode compartment with deionized water or a mixture of deionized Water and a minimum level of the separable electrolyte is preferably provided.
  • the membrane employed does not ordinarily act as a dialysis membrane in the absence of a potential between the electrodes (as during shutdown periods), there is little tendency for accumulated ions to rediffuse through the membrane unless the electrolyte level in the electrode compartment is relatively high. Any such tendency can be corrected by continual flushing of the membrane-enclosed compartment or by employing a membrane that is impermeable to water, and also by maintaining a low electrolyte level in the membrane-enclosed compartment.
  • a cathode compartment (or if a cationic vehicle is employed, the anode compartment) need not be constructed for all the electrode plates, but the surface area of an exposed membrane may be varied depending on the degree of control desirable and also surface area of the article coated.
  • anionic vehicles are employed, other alkaline anions may be purged from the anode compartment, for example, ammonia, organic amines, sodium ions and the like.
  • the selective filtration process employed in the process of the instant invention is any process which separates water from the electrodeposition bath through a physical barrier while retaining the solubilized resin components.
  • any means may be utilized which accomplishes this purpose.
  • Means may pass not only water but also solute of substantially lower molecular weight than the vehicle resin such as excess amine, carbonates, low molecular weight solvent and simple organic or inorganic anions and cations which may be present in the bath. Examples of means for accomplishing this separation are reverse osmosis, where water of high purity may be obtained, and ultrafiltration, which is especially preferred.
  • Ultrafiltration separates materials below a given molecular weight size from the electrodeposition bath. With properly selected membranes, this treatment does not remove in substantial amounts any product or desirable resin from the paint in the tank, but does remove anionic, cationic and nonionic materials from the paint in a ratio proportional to their concentration in the water phase of the paint. Thus, for example, it is possible to remove amines, alkaline metal ions, phosphates, chromates, sulfates, solvents and dissolved carbon dioxide, among others.
  • Ultrafiltration may be defined as a method of concentrating solute while removing solvent, or selectively removing solvent and low-molecular weight solute from a significantly higher molecular weight solute. From another aspect, it is a process of separation whereby a solution containing a solute of molecular dimensions significantly greater than the solvent is depleted of solute by being forced under a hydraulic pressure gradient to flow through a suitable membrane.
  • the first definition is the one most fittingly describes the term ultrafiltration as applied to an electrodeposition bath.
  • Ultrafiltration thus encompasses all membrane-moderated, pressure-activated separations wherein solvent or solvent and smaller molecules are separated from modest molecular weight macromolecules and colloids.
  • the term ultrafiltration is generally broadly limited to describing separations involving solutes of molecular dimensions greater than about ten solvent molecular diameters and below the limit of resolution of the optical microscope, that is, about 0.5 micron. In the present process, water is considered the solvent.
  • the basic ultrafiltration process is relatively simple. Solution to be ultrafiltered is confined under pressure, utilizing, for example, either a compressed gas or liquid pump in a cell, in contact with an appropriate filtration membrane supported on a porous support. Any membrane or filter having chemical integrity to the system being separated and having the desired separation characteristic may be employed. Preferably, the contents of the cell should be subjected to at least moderate agitation to avoid accumulation of the retained solute on the membrane surface with the attendant binding of the membrane. Ultrafiltrate is continually produced and collected until the retained solute concentration in the cell solution reaches the desired level, or the desired amount of solvent or solvent plus dissolved low molecular weight solute is removed.
  • a suitable apparatus for conducting ultrafiltration is described in US. Pat. No. 3,495,465, which is hereby incorporated by reference.
  • ultrafiltration membranes There are two types of ultrafiltration membranes.
  • solvent in the case of electrodeposition, water
  • the flow rate proportional to the pressure difierence, dissolved solutes, to the extent that their hydrated molecule dimensions are smaller than the smallest pores within the structure, will pass through, little impeded by the matrix. Larger size molecules, on the other hand, will become trapped therein or upon the external surface of the membrane and will thereby be retained.
  • microporous ultrafilters are inherently susceptible to internal plugging or fouling by solute molecules Whose dimensions lie within the pore size distribution of the filter, it is preferred to employ for a specific solute a microporous ultrafilter whose mean pore size is significantly smaller than the dimensions of the solute particle being retained.
  • the diffusive ultrafilter is a gel membrane through which both solvent and solutes are transported by molecular diffusion under the action of a concentration of activity gradient.
  • solute and solvent migration occurs via random thermal movements of molecules within and between the chain segments comprising the polymer network.
  • Membranes prepared from highly hydrophilic polymers which swell to eliminate standard water are the most useful dilfusive aqueous ultrafilter membranes. Since a diffusive ultrafilter contains no pores in the conventional sense and since concentration within the membrane of any solute retained by the membrane is low and time-independent, such a filter is not plugged by retained solute, that is, there is no decline in solvent permeability with time at a constant pressure. This property is particularly important for a continuous concentration or separation operation. Both types of filters are known in the art.
  • the presently preferred ultrafilter is an anisotropic membrane structure such as illustrated in FIG. 1.
  • This structure consists of an extremely thin, about one-tenth to about ten micron layer, of a homogeneous polymer 1 supported upon a thicker layer of a microporous opencelled sponge 2, that is, a layer of about 20 microns to about 1 millimeter, although this dimension is not critical.
  • this membrane can be further supported by a fibrous sheet, for example, paper, to provide greater strength and durability.
  • These membranes are used with a thin film or skin side exposed to the high pressure solution. The support provided to the skin by the spongy substrate is adequate to prevent film rupture.
  • Membranes useful in the process are items of commerce and can be obtained by several methods.
  • One general method is described in Belgian Pat. No. 721,058.
  • This patent describes a process which, in summary, comprises (a) forming a casting dope of the polymer in an organic solvent, (b) forming a film of the casting dope, and (c) preferentially contacting one side of said film with a diluent having high compatibility with the casting dope to effect precipitation of the polymer immediately upon coating the cast film with the diluent.
  • Membranes can be typically prepared from thermoplastic polymers such as polyvinyl chloride, polyacrylonitrile, polysulfones, poly (methyl methacrylate), polycarbonates, poly(n-butyl methacrylate), as well as a large group of copolymers formed from any of the monomeric units of the above polymers, including Polymer 360, a polysulfone copolymer. Cellulosic materials such as cellulose acetate may also be employed as membrane polymers.
  • thermoplastic polymers such as polyvinyl chloride, polyacrylonitrile, polysulfones, poly (methyl methacrylate), polycarbonates, poly(n-butyl methacrylate), as well as a large group of copolymers formed from any of the monomeric units of the above polymers, including Polymer 360, a polysulfone copolymer.
  • Cellulosic materials such as cellulose acetate may also be employed as membrane polymers.
  • Some examples of specific anisotropic membranes perable in the process of the invention include Diafiow membrane ultrafilter PM-30, the membrane chemical composition of which is a polysulfone copolymer. Polymer 360, and which has the following permeability characteristics
  • the membrane is chemically-resistant to acids (HCl, H 80 H PO all concentrates), alkalis, high phosphate buffer and solutions of common salts as Well as concentrated urea and guanadine hydrochloride.
  • the membrane is solvent-resistant to alcohol, acetone and dioxane.
  • the membrane is not solvent-resistant to dimethylformamide or dimethyl sulfoxide. This membrane is hereinafter referred to as Membrane A.
  • Dorr-Oliver XPA membrane the membrane chemical composition of which is Dynel (an acrylonitrile-vinyl chloride copolymer) and which has the following permeability characteristics:
  • Cytochrome C 12 600 50 100 a-Chymotripsinagen 24, 000 90 22 Ovalbumin 45, 000 100 4,5
  • Membrane B This membrane is hereinafter referred to as Membrane B.
  • Dorr-Oliver BPA type membrane the membrane chemical composition of which is phenoxy resin (polyhydroxyether), and which has the following permeability characteristics:
  • Membrane C This membrane is hereinafter referred to as Membrane C.
  • the microporous ultrafilters are generally isotropic structures, thus flow and retention properties are independent of flow direction. It is preferred to use an ultrafilter which is anisotropic in its microporous membrane structure, FIG. 2. In such a membrane, the pore size increases rapidly from one face to the other. When the finetextured side 4 is used in contact with the feed solution, this filter is less susceptible to plugging since a particle which penetrates the topmost layer cannot become trapped in the membrane because of the larger pore size 5 in the substrate.
  • the process of selective separation may be operated continuously or intermittently.
  • batch selective filtration or batch ultrafiltration a finite amount of material is placed in a cell which is pressurized. A solvent and lower molecular weight solutes are passed through the membrane. Agitation is provided by a stirrer, for example, a magnetic stirrer. Obviously, this system is best used for small batches of material.
  • a continuous selective filtration process is preferred. Using this technique, material is continuously recirculated under pressure over a membrane or series of membranes through interconnecting flow channels, for example, spiral flow channels.
  • the ultrafiltration process may be conducted as either a concentration process or a diafiltration process.
  • Concentration involves removing solvent and low molecular weight solute from an increasingly concentrated retentate. Filtration flow rate -'will decrease as the viscosity of the concentrate increases.
  • Diafiltration is a constant volume process whereby the starting material is connected to a reservoir of pure solvent, both of which are placed under pressure simultaneously. Once filtration begins, the pressure source is shut off in the filtration cell and thus, as the filtrate is removed, an equal volume of new solvent is introduced into the filtration cell to maintain the pressure balance.
  • the configuration of the filter may also vary widely and is not limiting to the operation of the process.
  • the filter or membrane may, for example, be in the form of a sheet, tubes, or hollow fiber bundles, among other configurations.
  • C is the initial solute concentration
  • C is the final solute concentration of the retentate
  • V is the volume of solute delivered to the cell (or the volume of the filtrate collected)
  • V is the initial solution volume (which remains constant).
  • the ultrafiltration process employing a difiusive membrane ultrafilter retains the solubilized vehicle resin while passing water and low molecular weight solute, especially those with a molecular weight below about 500.
  • the filters discriminate as to molecular size rather than actual molecular weight, thus, these molecular weights merely establish an order of magnitude rather than a distinct molecular weight cut-off.
  • the particular charge on the low molecular weight solutes and ions that pass through the ultrafilter membrane is of little importance since there is no E.M.F. across the ultrafilter membrane, as contrasted with the electrodialysis membrane.
  • the retained solutes may, in fact, be colloidal dispersions or molecular dispersions rather than true solutes.
  • a portion of the contents of the coating zone is continuously or intermittently passed, usually under pressure created by a pressurized gas or by means of pressure applied to the contained fluid, into contact with the ultrafilter.
  • the egress side of the filter may be maintained at a reduced pressure to create the pressure difference.
  • the pressures necessary are not severe.
  • the maximum pressure in part, depends on the strength of the filter.
  • the minimum pressure is that pressure required to force water and low molecular weight solute through the filter at a measurable rate.
  • the operating pressures are between about and 150 p.s.i., preferably between about and 75 psi.
  • the ultrafilter should have a minimum initial flux rate, measured with the composition to be treated of at least about 3 gals/sq. ft./day (24 hours) and preferably at least about 4.5 gaL/sq. ft./day.
  • the bath composition should be in motion at the face of the filter to prevent the retained solute from impeding the fiow through the filter. This may be accomplished by mechanized stirring or by fluid flow with a force vector to the filter surface.
  • the retained solutes comprising the vehicle resin and pigment can be returned to the electrodeposition bath.
  • the concentrate may be reconstituted by the addition of water either before entry to the bath or by adding water directly to the bath.
  • the ultrafiltrate may readily be utilized to rinse the paint dragout back into the electrocoating bath or, if desirable, the rinsings may be passed to the drain.
  • a number of electrodepositable resins are known and can be employed to provide the electrodepositable compositions which may be utilized within the scope of ultrafiltration.
  • Virtually any water-soluble, water-dispersible or water-emulsifiable vehicle resin in an aqueous medium can be electrodeposited and, if film-forming, provides coatings which may be suitable for certain purposes.
  • the resins are ionically-solubilized synthetic resins.
  • the present invention is applicable to any 'such process.
  • the common electrodepositable compositions are those based upon polycarboxylic acid resins.
  • Inorganic bases such as metal hydroxides, especially potassium hydroxide, can be used, as can ammonia or organic bases such as amines.
  • Watersoluble amines are often preferred. Commonly used amines include ethylamine, diethylamine, triethylamine, diethanolamine, and the like.
  • base-solubilized polyacids which may be employed as electrodeposition vehicles include those taught in US. Pat. No. 3,392,165, which is incorporated herein by reference, wherein the acid groups rather than being solely polycarboxylic acid groups contain mineral acid groups such as phosphonic, sulfonic, sulfate and phosphate groups.
  • the process of the instant invention is also applicable to cationic type vehicle resins, that is, vehicle resins which deposit on the cathode.
  • vehicle resins that is, vehicle resins which deposit on the cathode.
  • These include polybases solubilized by means of an acid, for example, an amine-terminated polyamine or an acrylic polymer solubilized with acetic acid.
  • Other cationic polymers include reaction products of polyepoxides with amino-substituted boron esters and reaction products of polyepoxides with hydroxyl or carboxyl-containing amines.
  • the electrodepositable composition In addition to the vehicle resin, there may be present in the electrodepositable composition any desired pigment or pigment composition, including practically any of the conventional types of pigments employed in the art. Sometimes there is incorporated into the pigment composition a dispersing or surface-active agent. Usually the pigment and surface-active agent, if any, are ground together in a portion of the vehicle, or alone in an aqueuos medium, to make a paste and this is blended with the vehicle to produce a coating composition.
  • additives to aid dispersibility, viscosity and/or film quality, such as a non-ionic modifier or solvent.
  • additives such as antioxidants, wetting agents, anti-foaming agents, fungicides, bactericides and the like.
  • deionized water i.e., water from which free ions have been removed by the passage through ion exchange resins.
  • Electrodepositable compositions while referred to as solubilized, in fact are considered a complex solution, dispersion, suspension or combination of one or more of these classes, in water, which acts as an electrolyte, under the influence of an electric current. While, no doubt, in some circumstances the vehicle resin is in solution, it is clear that in some instances and perhaps in most the vehicle resin is a dispersion which may be called a molelcular dispersion of molecular size between a colloidal suspension and a true solution.
  • the typical industrial electrodepositable composition also contains pigments, crosslinking resins and other adjuvants which are frequently combined with the vehicle resin in a chemical and a physical relationship.
  • the pigments are usually ground in a resin medium and are thus wetted with the vehicle resin.
  • an electrodepositable composition is complex in terms of the freedom or availability with respect to removal of a component or in terms of the apparent molecular size of a given vehicle component.
  • Apparatus for carrying out the present process comprises an electrodeposition bath in which the electrode upon which the coating is deposited is separated from the counterelectrode, at least in part, by a membrane, semipermeable or selecetively permeable, thus forming an electrodialysis compartment, dividing the coating zone from the counter-electrode.
  • a selective separation unit is connected to the coating bath zone and has a physical barrier which passes aqueous efiiuent While retaining the solubilizing resin components.
  • Means are provided for operating the selective separation unit continuously or intermittently to treat at least a portion of the contents from the coating zone.
  • the electrodialysis membrane be a plant fiber or an ion-exchange membrane and that the compartment comprising the electrodialysis membrane and counter-electrode have a suitable means for flushing the compartment.
  • the preferred selective separation unit is an ultrafiltration unit.
  • FIG. 3 is a schematic drawing depicting one embodiment of electrocoating apparatus suitable for use with the treating method herein described.
  • a chemically-resistant tank 1 contains the aqueous coating composition.
  • the electrode compartment 3, immersed in tank 1 and attached to tank 1 by fastening means 7 is fitted with a power source connector 5, input line 9 and output line 11, to facilitate flushing of electrode compartment 3 as hereinbefore described.
  • the electrode in electrode compartment 3 is connected to a DC. power source 21 by means of electrical conductor 23.
  • the power source 21 is also connected to bus bar 27 via conductor 25.
  • the bus bar 27 contains electrical contact plate 29 which is employed to energize hanger 31.
  • Articles 33, to be coated, are shown approaching tank 1, immersed in, and exiting and are in electrical connection with hanger 31.
  • Hanger 31 is supported by grounded conveyor 37 and insulated from the energized contact plate 29 by means of insulator 35.
  • tank 1 is connected to selective separator 13 via valve 15.
  • the aqueous composition continuously or intermittently enters the selective separator 13 through valve 15, and upon processing the concentrated component is returned to tank 1 via line 17.
  • the efiiuent from the selective separator is removed to waste or further processing via line 19.
  • the tank may be several electrode compartments or, in some instances, it may be feasible to operate the tank periodically without employing membranes. In such a case, the electrode is simply removed from the compartment and thus installed in the bath without being enclosed by a membrane.
  • the selective separator may also be operated when the electrodialysis apparatus is disengaged, simultaneously with the electrodialysis apparatus, when there is no coating being deposited, or while deposition is taking place but in the absence of electrodialysis.
  • FIG. 3 is not intended to be a complete description of the required piping, pumping, power sources and electrical circuitry required, but is only presented by way of illustration and is not to be construed as limiting the invention disclosed herein in any way.
  • PASTE A Parts by weight 20 percent maleinized oil (total solids content 97.6 percent) 14.30 Diethylamine 2.08
  • Dispersing agent (combination oil-soluble sulfonate and non-ionic sulfactant-Witco 912) 1.48
  • the vehicle resin employed in formulating Composition C was comprised of a maleinized tall oil fatty acid-adipic acid ester of a styrene-ally] alcohol copolymer of 1100 molecular weight and a hydroxyl functionality of 5 comprising 38.5 percent of the copolymer, 55.5 percent tall oil fatty acids, and 6.0 percent maleic anhydride as a 100 percent solids vehicle having an intrinsic viscosity of 120,000 centipoises and an acid number of 40.6.
  • Composition C was reduced to produce Composition D (below).
  • Composition D had the following properties:
  • An electrodepositing apparatus which enabled the continual coating of coil stock was filled with 6600 parts of Composition D.
  • the electrodepositing apparatus was fitted with two cathode compartments, each cathode compartment being separated from the anode compartment by a cloth membrane.
  • the canvas membrane employed comprised a plain weave (Shachi No. 1) linen membrane.
  • the cathode compartment utilized 1380 parts of deionized water as a receiving solvent, into which a small amount of an electrolyte may be added which facilitates ease of starting the electrodialysis process by lowering the resistivity of the electrolyte.
  • Such electrolytes may include amines and salts such as ammonium sulphate, sodium sulphate, soda ash, potassium hydroxide, and the like.
  • the diffusate may be periodically removed and replaced with fresh receiving solvent, or if desirable, the diffusate may be continually purged and replaced with fresh receiving solvent, which will prevent a buildup of deleterious components in the diffusate.
  • Composition D was continually deposited on aluminum coil stock (4 inches wide) and as the coating solids content was depleted, 220 parts of Composition C were added at the termination of every 4: cycle.
  • cycle it is meant that suiiicient bath coating solids have been deposited on the aluminum stock, which would have depleted the bath of its entire solids content had it not been for the additions after each Ms cycle. Also, after each A cycle approximately 600 parts of the ditfusate was exchanged with fresh receiving solvent.
  • the dialyzate (the dialyzed coating Composition D) had the following characteristics:
  • the dialyzate (dialyzed coating Composition D) was then subjected to an ultrafiltration process which employed a Membrane B type at 50 p.s.i.
  • the Membrane B had the characteristics as hereinabove described.
  • the entire composition was subjected to ultrafiltration whereby 3300 parts of ultrafiltrate were removed; dialyzate was again rediluted and subjected to ultrafiltration whereby an additional 2780 parts of ultrafiltrate were removed.
  • the ultrafiltrate had the following characteristics:
  • Composition E was subjected to electrodialysis and ultrafiltration in a manner similar to that employed in Cycle 1 except that in the second cycle the ditfusate was continually removed and replaced at the rate of 100 cc. per minute with fresh receiving solvent.
  • Dialyzed trate constituted 1st cycle composi- Ultrareconsti- 2nd cycle composi Ultrareconstiwith those destarting tion D Difiufiltrate tuted with starting tion E Difiufiltrate tuted with sirable compo- Oomposiafter one sate after after one deionized Composiafter 2nd sate for for 2nd deionized nents which tion D cycle one cycle cycle water tion E cycle 2nd cycle cycle water were removed Total parts by weight 6, 600 6, 395 5, 640 6,080 5, 940 6, 600 6, 964 16, 312 5, 537 6, 607 6, 600 pH 9.
  • the dialyzed concentrate in preparation for a second cycle of electrodialysis and ultrafiltration, was reconstituted as follows:
  • apparatus used in this invention provides for the accelerated removal of water from the coating zone. For example, it is especially useful to remove excess water which has been introduced into the coating zone by rinsing coated articles over the coating zone. By such rinsing over the coating zone, the drag-out material adhering to the electrocoated parts is returned to the coating zone, thus any solubilizing agent which would have been removed is returned to the coating zone.
  • the electrodialysis and selective separation steps are operated for a time sufficient to remove both the excess water and the solubilizing agent which was returned to the coating zone.
  • the potassium content after electrodialysis and ultrafiltration (see Table I).
  • the potassium content increased from 23.7 to 28. 6 as grams of KOH; this increase can 'be readily explained as due to the electrodeposition process in that, as the resin is deposited on the anode, the potassium is released to accumulate in the bath, and also as new feed material is introduced into the bath, the concentration of potassium increases because potassium hydroxide has been utilized as a solubilizing agent in the said feed material.
  • the electrodialysis alone is not sufficient to maintain the potassium content at the initial concentration of Composition D. However, upon subjecting the dialyzed Composition D to ultrafiltration, the potassium content may be restored to an operable level.
  • the second cycle 16 utilizing Composition E produced results similar to those obtained in the hereinabovedescribed first cycle. In production operation, ultrafiltration and electrodialysis may 'be used simultaneously, thus pH, conductivity, etc. would be relatively constant.
  • the resin utilized was a tall oil fatty acid-epoxy ester comprised of 45.08 percent Epon resin (Shell Chemicals Epon 829), 25.66 percent tall oil fatty acid, and 29.26 percent maleinized tall oil fatty acid.
  • the resin had the following characteristics:
  • Composition G was reduced to produce Composition H as follows:
  • COMPOSITION H Parts by weight Composition B 892.42 Deionized water 2537.58
  • Composition H A total of 6600 parts of Composition H were charged into an electrocoating apparatus and the bath contents were turned over three times in a manner previously disclosed. After Composition H had been subjected to electrodialysis and ultrafiltration, it was reconstituted (Composition I) by replacing those minute essential components that were removed during the electrodialysis and ultrafiltration processes. Likewise, after the second cycle, Com position I was reconstituted (Composition J) in a similar manner.
  • the present process is of particular importance when an ion-exchange membrane is utilized in the electrodi step because of the low permeability of membranes, which tends to cause a build-up of water in the coating zone, especially when electrocoated articles i ....-20181--..-.Iiilllil-l.
  • a method of electrocoating an electrically-conductive surface from an electrodeposition bath comprising ionically solubilized synthetic resin in aqueous medium comprising subjecting at least a portion of the electrodeposition bath to electrodialysis wherein ions of charge opposite to said resin are passed through a membrane under an electromotive force and removed from the electrodeposition bath and simultaneously, or at a separate time subjecting at least a portion of the electrodeposition bath to an ultrafiltration process wherein an ultra'sfiltration membrane passes water and solute of substantially lower molecular size than said resin, while retaining said resin and returning retentate of the ultrafiltration process to the electrodeposition bath.
  • a method as in claim 1 wherein the electrodialysis is carried out by interposing a semi-permeable or selectively-permeable membrane between said surface being electrocoated and a counter electrode in the electrodeposition bath during the electrocoating process.
  • an electrodeposition process which comprises passing an electric current through an aqueous bath containing ionically-solubilized synthetic resin in electrical contact between an article to be coated, serving as an electrode and a counter-electrode
  • the improvement which comprises carrying out the process with the article being coated and a counter-electrode being separated by an electrodialysis membrane in an electrodialysis compartment into which ions are passed through said membrane while continuously or intermittently subjecting at least a portion of said bath to an ultrafiltration process wherein an ultrafiltration membrane passes Water and solute of substantially lower molecular size than said resin, while retaining said resin, and returning retentate of the ultrafiltration process to said bath.
  • a method as in claim 8 wherein the electrodialysis membrane is a cation-exchange membrane having a pore size of less than 20A.
  • a method as in claim 8 wherein the electrodialysis membrane is a cloth of plant fibers.
  • electrodialysis membrane is comprised of a cloth prepared by plain Weaving linen fibers.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Water Supply & Treatment (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Separation Using Semi-Permeable Membranes (AREA)
  • Paints Or Removers (AREA)
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Cited By (12)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3905886A (en) * 1974-09-13 1975-09-16 Aqua Chem Inc Ultrafiltration and electrodialysis method and apparatus
EP0028837A3 (en) * 1979-11-13 1982-04-14 Diamond Shamrock Corporation An electrolytic-ultrafiltration apparatus and process for recovering solids from a liquid medium
FR2517706A1 (fr) * 1981-12-08 1983-06-10 Ppg Industries Inc Procede de traitement, par ultrafiltration et electrodialyse externes, du liquide d'un bain d'electrodeposition
US4412922A (en) * 1980-07-02 1983-11-01 Abcor, Inc. Positive-charged ultrafiltration membrane for the separation of cathodic/electrodeposition-paint compositions
EP0156341A2 (en) 1984-03-28 1985-10-02 Ppg Industries, Inc. Treatment of ultrafiltrate by electrodialysis
US4775478A (en) * 1986-09-03 1988-10-04 Basf Aktiengesellschaft Process for removing acid from cathodic electrocoating baths
EP0271015A3 (en) * 1986-12-10 1989-06-07 Basf Aktiengesellschaft Electrodialysis process for removing acids from cataphoretic painting baths
US5114554A (en) * 1987-12-02 1992-05-19 Basf Aktiengesellschaft Removal of acid from cathodic electrocoating baths by electrodialysis
DE4207425A1 (de) * 1992-03-09 1993-09-16 Eisenmann Kg Maschbau Verfahren zur lack-overspray-rueckgewinnung bei spritzapplikationen und vorrichtung zur verfahrensdurchfuehrung
WO2001060501A1 (en) * 2000-02-15 2001-08-23 Celtech, Inc. Device and process for electrodialysis of ultrafiltration permeate of electrocoat paint
CN109060065A (zh) * 2018-06-29 2018-12-21 湖南文理学院 一种城市湿地的污水容纳量研究方法
CN115043466A (zh) * 2022-08-10 2022-09-13 杭州水处理技术研究开发中心有限公司 一种高盐高浓有机废水处理装置

Families Citing this family (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3945900A (en) * 1972-05-02 1976-03-23 Dorr-Oliver Incorporated Electro ultrafiltration process and apparatus
JPS5210667B2 (enExample) * 1973-06-07 1977-03-25
GB2162542A (en) * 1984-06-05 1986-02-05 Carrs Paints Limited Electro painting apparatus; degassifying electropainting bath
FR2567914B1 (fr) * 1984-07-19 1989-04-07 Univ Languedoc Procede de recuperation de cations metalliques en continu a partir de solutions diluees et appareil pour sa mise en oeuvre
US4643815A (en) * 1984-11-30 1987-02-17 Metokote Corporation Electrocoating method and apparatus
US4663014A (en) * 1986-01-02 1987-05-05 I. Jay Bassett Electrodeposition coating apparatus
USD303282S (en) 1986-01-02 1989-09-05 I. Jay Bassett Combined tank and cover assembly for use in electrodeposition coating operations
US4755273A (en) * 1986-01-02 1988-07-05 Bassett I Jay Cover for coating tanks
AU5957094A (en) * 1993-01-15 1994-08-15 Allied-Signal Inc. Process for producing ion exchange membranes, and the ion exchange membranes produced thereby
JP2751090B2 (ja) * 1993-04-21 1998-05-18 日本錬水株式会社 純水製造装置
GB2361479A (en) * 2000-04-11 2001-10-24 Secr Defence Electric-field structuring of composite materials
DE10132349B4 (de) * 2001-07-04 2006-08-17 Eisenmann Maschinenbau Gmbh & Co. Kg Verfahren und Anlage zur kataphoretischen Tauchlackierung von Gegenständen
DE10224817B4 (de) * 2002-06-05 2005-04-14 Atotech Deutschland Gmbh Verfahren und Vorrichtung zum vertikalen Eintauchen von folienartigem Behandlungsgut in Bädern von Galvanisier- und Ätzanlagen
DE102008056884A1 (de) * 2008-11-12 2010-06-02 Südzucker AG Mannheim/Ochsenfurt Elektro-Ultrafiltrationsverfahren zur Bestimmung der Löslichkeit und Mobilität von Schwermetallen und/oder Schadstoffen für Abfall- und Altlastenmaterialien sowie Schwermetall- und/oder Schadstoff kontaminierte Böden
US11251635B2 (en) 2017-12-19 2022-02-15 Welch Allyn, Inc. Vital signs monitor with a removable and dischargable battery

Family Cites Families (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3230162A (en) * 1963-08-14 1966-01-18 Ford Motor Co Electropainting process and paint binder concentrate composition therefor
DE1266098B (de) * 1963-11-30 1968-04-11 Siemens Ag Verfahren zum elektrophoreitischen Beschichten von elektrisch leitenden Werkstoffen unter Verwendung von waessrigen Suspensionen
US3355373A (en) * 1963-12-30 1967-11-28 Ford Motor Co Method for adjusting the bath composition in a continuous electrodeposition process
GB1106979A (en) * 1964-04-08 1968-03-20 Ici Ltd Electro-deposition of film-forming material
US3444066A (en) * 1966-12-07 1969-05-13 Ford Motor Co Method of electrically induced deposition of paint on conductors
SE442411B (sv) * 1969-04-09 1985-12-23 Ppg Industries Inc Sett att reglera sammansettningen av ett elektrofores - eller eldopplackeringsbad
US3671412A (en) * 1970-04-28 1972-06-20 Du Pont Process for the removal of ionic contaminants from an electrocoating bath
US3679565A (en) * 1971-07-27 1972-07-25 Scm Corp Process for electrolytic treatment of liquors using pressure cell with porous electrode means

Cited By (18)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3905886A (en) * 1974-09-13 1975-09-16 Aqua Chem Inc Ultrafiltration and electrodialysis method and apparatus
EP0028837A3 (en) * 1979-11-13 1982-04-14 Diamond Shamrock Corporation An electrolytic-ultrafiltration apparatus and process for recovering solids from a liquid medium
US4331525A (en) * 1979-11-13 1982-05-25 Diamond Shamrock Corporation Electrolytic-ultrafiltration apparatus and process for recovering solids from a liquid medium
US4412922A (en) * 1980-07-02 1983-11-01 Abcor, Inc. Positive-charged ultrafiltration membrane for the separation of cathodic/electrodeposition-paint compositions
FR2517706A1 (fr) * 1981-12-08 1983-06-10 Ppg Industries Inc Procede de traitement, par ultrafiltration et electrodialyse externes, du liquide d'un bain d'electrodeposition
EP0156341A2 (en) 1984-03-28 1985-10-02 Ppg Industries, Inc. Treatment of ultrafiltrate by electrodialysis
US4581111A (en) * 1984-03-28 1986-04-08 Ppg Industries, Inc. Treatment of ultrafiltrate by electrodialysis
EP0156341A3 (en) * 1984-03-28 1987-01-07 Ppg Industries, Inc. Treatment of ultrafiltrate by electrodialysis
US4775478A (en) * 1986-09-03 1988-10-04 Basf Aktiengesellschaft Process for removing acid from cathodic electrocoating baths
EP0271015A3 (en) * 1986-12-10 1989-06-07 Basf Aktiengesellschaft Electrodialysis process for removing acids from cataphoretic painting baths
US4883573A (en) * 1986-12-10 1989-11-28 Basf Aktiengesellschaft Removal of acid from cathodic electrocoating baths by electrodialysis
US4971672A (en) * 1986-12-10 1990-11-20 Basf Aktiengesellschaft Removal of acid from cathodic electrocoating baths by electrodialysis
US5114554A (en) * 1987-12-02 1992-05-19 Basf Aktiengesellschaft Removal of acid from cathodic electrocoating baths by electrodialysis
DE4207425A1 (de) * 1992-03-09 1993-09-16 Eisenmann Kg Maschbau Verfahren zur lack-overspray-rueckgewinnung bei spritzapplikationen und vorrichtung zur verfahrensdurchfuehrung
WO2001060501A1 (en) * 2000-02-15 2001-08-23 Celtech, Inc. Device and process for electrodialysis of ultrafiltration permeate of electrocoat paint
CN109060065A (zh) * 2018-06-29 2018-12-21 湖南文理学院 一种城市湿地的污水容纳量研究方法
CN115043466A (zh) * 2022-08-10 2022-09-13 杭州水处理技术研究开发中心有限公司 一种高盐高浓有机废水处理装置
CN115043466B (zh) * 2022-08-10 2022-12-09 杭州水处理技术研究开发中心有限公司 一种高盐高浓有机废水处理装置

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US3784460A (en) 1974-01-08
GB1383365A (en) 1974-02-12
CA963425A (en) 1975-02-25
FR2128853A1 (enExample) 1972-10-20
FR2128853B1 (enExample) 1974-08-30
DE2211318B2 (de) 1980-10-23
DE2211318A1 (de) 1972-09-21

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