EP0172541B1 - Procédé pour régler la teneur en électrolytes de dispersions aqueuses de résine - Google Patents
Procédé pour régler la teneur en électrolytes de dispersions aqueuses de résine Download PDFInfo
- Publication number
- EP0172541B1 EP0172541B1 EP85110298A EP85110298A EP0172541B1 EP 0172541 B1 EP0172541 B1 EP 0172541B1 EP 85110298 A EP85110298 A EP 85110298A EP 85110298 A EP85110298 A EP 85110298A EP 0172541 B1 EP0172541 B1 EP 0172541B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- aqueous resin
- water
- filter modules
- resin dispersions
- bath
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
Links
Classifications
-
- 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
Definitions
- the invention relates to a method for controlling the electrolyte content of aqueous resin dispersions.
- a process for the pretreatment and coating of metallic surfaces, in particular steel or iron surfaces, is known under the trademark “Autophoretic® Chemical Coating”, in which the acidic dispersion of an organic resin with pigments and auxiliaries in water is brought into contact with metallic surfaces and thereby in certain circumstances, an organic coating is produced by a chemical reaction of the substrate with the coating material on the metallic surfaces. Because of its numerous advantages, this method is used to an increasing extent in the metalworking industry to achieve good corrosion protection, particularly on metal parts that are difficult to access.
- the “Autophoretic® Chemical Coating” (ACC) process is essentially based on this [cf. R.
- the pickling reaction usually releases more iron than is necessary for the desired coating reaction.
- the excess iron ions accumulate in the coating bath and lead to destabilization of the dispersion. If certain limits are exceeded, the bath content coagulates and the desired coating reaction can no longer take place.
- US Pat. No. 3,791,431 discloses a process for coating metallic surfaces with ACC dispersions by precipitating excess iron (III) ions with phosphoric acid or alkali metal fluorides as phosphate or complex fluorides or by adding ethylenediaminetetraacetic acid (EDTA) or organic mono- or oligocarboxylic acids (Citric acid, gluconic acid, tartaric acid or lactic acid) complexed and thereby removed from the solution or converted into a form that no longer leads to destabilization of the dispersions in the coating baths.
- EDTA ethylenediaminetetraacetic acid
- organic mono- or oligocarboxylic acids Citric acid, gluconic acid, tartaric acid or lactic acid
- the precipitates or complexes also remain in the bath and partially dissolve again when the pH is adjusted by adding hydrofluoric acid.
- the inorganic ions remaining in the bath solution thus further destabilize the dispersion.
- US Pat. No. 3,839,097 describes a method for stabilizing ACC baths, which consists in passing the baths over ion exchangers after the addition of surface-active substances, which are able to remove excess amounts of metal ions from the baths which impair the stability of the dispersions .
- This method is also associated with great expenditure on equipment, and an impairment of the aqueous dispersions by pumping over the exchange columns is unavoidable, so that a deterioration in the bath quality must be accepted.
- the object was therefore to provide a process which can be used to remove metal ions from acidic, aqueous baths containing organic coating compositions, in particular baths suitable for the ACC process, which impair the stability of the dispersion and thus the coating Can have a lasting effect on the effect of the baths.
- the additional task was to carry out the removal of the interfering metal ions from the baths in a simple manner and without additional pumping or filtering operations, since the shear forces acting on the bath solutions likewise lead to destabilization of the dispersion.
- the invention thus relates to a method for controlling the electrolyte content of aqueous resin dispersions by means of membrane filtration, which is characterized in that semipermeable filter modules with average pore sizes which are smaller than are optionally continuously and with the inclusion of known measuring, regulating and / or metering instruments the average micelle size of the organic components of the aqueous resin dispersions, internal diameters from 0.05 to 1.0 cm and lengths of the filter modules from 0.1 to 10 m per 10 l bath volume in contact with the aqueous resin dispersions, the filter modules with water flows through, whereby the water is conducted in a separate closed circuit and, by sucking or pumping the water, a hydrostatic pressure of 40 to 500 mbar is generated on the outer membrane surface facing the resin dispersion, the aqueous resin dispersions water, including foreign ions to be separated, to a desired level rt withdrawn and enriched in the aqueous circulation phase and compensates for the loss of water and desired electrolytes in the aque
- the ultrafiltration not the aqueous resin dispersion is pumped through the filter module, but water, preferably fully demineralized water is used.
- water preferably fully demineralized water is used.
- Highly porous semipermeable microfiltration membranes preferably in tube form, are used as filter modules, and water flows through them from the inside.
- the membrane material consists of a polyolefin that is resistant to alkalis and acids in the entire pH range as well as a variety of organic solvents, for example made of polypropylene.
- Accurel ® membranes are preferably used, which are manufactured as tubes and processed into filtration modules with semi-permeable tube walls.
- the membranes are self-supporting and can withstand all mechanical loads during filtration without supporting materials.
- the method according to the invention is not limited to membranes in tube form; rather, membranes with a different geometry, for example membranes in the shape of cuboids or cylinders or filter candles, can be used by means of the materials mentioned.
- the tubular membranes for the filter modules have average pore sizes that are less than the average micelle size of the organic components of the aqueous resin dispersions. This is necessary so that non-organic components of the aqueous resin dispersions can penetrate the membrane surface.
- the average pore size is preferably 0.17 ⁇ m, particularly preferably 0.1 ⁇ m. Filter modules whose membranes have this average pore size cannot be blocked by organic components of the aqueous resin dispersions. Bath components that settle on the outer module surface can be easily removed using known backwashing techniques or easily rinsed off after using the filter modules. In contrast, it was found in prior art ultrafiltration processes that the dispersions were broken by the shear forces of the filtration process and that a hard coagulate had settled on the pressure side of the filter modules, which could not be removed again.
- the length of the semi-permeable tubular filter modules which are preferably used, can be varied depending on the volume of the aqueous dispersion bath in order to achieve efficient control of the electrolyte content.
- filter modules with a length of between 0.1 and 10 m per 10 l bath volume are used.
- the modules have an inside diameter of 0.05 to 1.0 cm.
- the polypropylene tube modules described, for example Accurel @ membranes, are immersed in the aqueous resin dispersions and their ends are connected to one or more separate containers which preferably contain demineralized water.
- One or more pumps are then attached to the filter module concluded that there is a separate closed circuit between the supply water and the filter module.
- These pumps can be either suction or pressure pumps, so that the fully demineralized water is either sucked in from the module outlet side or pumped into the module from the module inlet side.
- Pressure pumping through the modules from the inlet side must take place at flow speeds which ensure that the resulting dynamic pressure is lower than the static pressure on the outer surface of the modules. This depends, among other things, on the immersion depth of the modules in the bathroom. A higher back pressure would lead to the passage of water from the closed circuit into the resin dispersion.
- the circulating water is advantageously sucked through the filter module, so that a pressure drop sufficient for an efficient separation of the metal ions is built up.
- the flow in the tubular filter module reduces the hydrostatic pressure within the module.
- the pressure on the outer membrane surface facing the aqueous resin dispersion rises to values of 40 to 500 mbar.
- the pressure difference for a tubular filter module of 290 cm in length and an inside diameter of 0.55 cm with a flow volume of 20 l ⁇ h -1 is 47.4 mbar, at 60 l ⁇ h -1 at 200 mbar and 100 l H-1 at 410 mbar.
- low-molecular components for which the membrane of the filter modules is permeable, enter the interior of the modules from the acidic aqueous resin dispersion and are flushed away with the water flow.
- Low molecular weight dispersion components that can pass through the membrane are primarily water and foreign ions, such as Fe 3 +, H +, F-, PO 4 3- and SO 4 2- .
- Higher molecular components of the aqueous resin dispersions, such as. B. resin wetting micelles do not pass through the membrane, because - as mentioned above - the average pore size of the membranes used has a value which is smaller than the average micelle size of the resin dispersion to be treated.
- the separation process can be continued until, above all, the value of foreign ions in the aqueous resin dispersion reaches the desired value.
- the content of iron (III) ions can be reduced to a value which makes a destabilizing effect of the metal ions on the resin dispersion impossible. This value is e.g. B. at 1.5 to 4.5 g of Fe (III) per liter of bath solution.
- the electrolyte content can be checked either by determining the value of electrolytes in the aqueous resin dispersion or by determining the value of electrolytes in the aqueous circulation phase. It should be noted that the loss of water and desired electrolytes in the aqueous resin dispersion by adding the respective components, e.g. B. water and / or mineral acid, such as hydrofluoric acid, etc., is adjusted again to the desired value.
- the respective components e.g. B. water and / or mineral acid, such as hydrofluoric acid, etc.
- the described method for controlling the electrolyte content of aqueous resin dispersions by means of membrane filtration is optionally carried out continuously and using known measuring, regulating and / or metering instruments.
- the loss of water and electrolytes desired in the aqueous resin dispersions is compensated for by automatic metering in of the necessary components, such as fully demineralized water, acid, etc.
- the method according to the invention for controlling the electrolyte content of aqueous resin dispersions is preferably applied to dispersions which are used in the technology of the ACC method and whose content of metal ions has to be kept below a certain threshold value, so that the dispersions do not become unstable because metal ions compensate for the effects of surface-active substances such as anionic and nonionic wetting agents.
- the control of the content of such bath components is advantageously carried out without the addition of further foreign ions, which inevitably influence the pH or other bath parameters, which makes the desired formation of homogeneous protective layers on metal surfaces difficult or even impossible.
- the fact that it is not the resin dispersion of the coating bath but the cleaning liquid that is passed through the filter modules also prevents mechanical forces from having a destabilizing effect on the aqueous resin dispersions in a simple and surprisingly efficient manner.
- a coating bath described in Example 1 was operated in the same arrangement with a pump output of 55.3 1 h -1. After 4.5 hours, the weight increase of the demineralized water was 1714 g. 849 ppm of iron and a rise in conductivity from 5.3 ⁇ S to 1237 ⁇ S were measured in the water of the reservoir.
- the weight gain of the demineralized water was 1300 g.
- the iron content had dropped from 3000 ppm to 1743 after making up for the loss of liquid due to deionized water.
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Engineering & Computer Science (AREA)
- Separation Using Semi-Permeable Membranes (AREA)
- Processes Of Treating Macromolecular Substances (AREA)
- Electric Double-Layer Capacitors Or The Like (AREA)
- Manufacture Of Macromolecular Shaped Articles (AREA)
- Fuel Cell (AREA)
- Measuring Oxygen Concentration In Cells (AREA)
Claims (8)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
AT85110298T ATE43369T1 (de) | 1984-08-25 | 1985-08-17 | Verfahren zur steuerung des elektrolytgehaltes waessriger harzdispersionen. |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
DE19843431276 DE3431276A1 (de) | 1984-08-25 | 1984-08-25 | Verfahren zur steuerung von elektrolytgehaltes waessriger harzdispersionen |
DE3431276 | 1984-08-25 |
Publications (2)
Publication Number | Publication Date |
---|---|
EP0172541A1 EP0172541A1 (fr) | 1986-02-26 |
EP0172541B1 true EP0172541B1 (fr) | 1989-05-24 |
Family
ID=6243856
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP85110298A Expired EP0172541B1 (fr) | 1984-08-25 | 1985-08-17 | Procédé pour régler la teneur en électrolytes de dispersions aqueuses de résine |
Country Status (11)
Country | Link |
---|---|
US (1) | US4639319A (fr) |
EP (1) | EP0172541B1 (fr) |
JP (1) | JPS6169837A (fr) |
AT (1) | ATE43369T1 (fr) |
AU (1) | AU571106B2 (fr) |
BR (1) | BR8504040A (fr) |
CA (1) | CA1240272A (fr) |
DE (2) | DE3431276A1 (fr) |
ES (1) | ES8605008A1 (fr) |
MX (1) | MX168157B (fr) |
ZA (1) | ZA856438B (fr) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE4204700A1 (de) * | 1992-02-17 | 1993-08-19 | Henkel Kgaa | Verfahren zur abtrennung anorganischer salze |
US5393416A (en) * | 1993-01-26 | 1995-02-28 | Henkel Corporation | Apparatus for maintaining a stable bath for an autodeposition composition by periodically separating particular metal ions from the composition |
JPH11129629A (ja) * | 1997-10-27 | 1999-05-18 | Fuji Photo Film Co Ltd | 記録材料およびその製造方法 |
DE102011087314A1 (de) | 2011-11-29 | 2013-05-29 | Henkel Ag & Co. Kgaa | Verfahren zur Regeneration wässriger Dispersionen sowie Zellpaket für die Elektrodialyse |
Family Cites Families (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
GB430426A (en) * | 1933-12-18 | 1935-06-18 | Rubber Producers Res Ass | Improvements in and relating to the purification and concentration of latex |
US2330672A (en) * | 1939-07-11 | 1943-09-28 | Honig P | Process and apparatus for dialyzing latex |
US2276986A (en) * | 1939-09-09 | 1942-03-17 | Bell Telephone Labor Inc | Latex |
NL269380A (fr) * | 1960-09-19 | |||
DE1266098B (de) * | 1963-11-30 | 1968-04-11 | Siemens Ag | Verfahren zum elektrophoreitischen Beschichten von elektrisch leitenden Werkstoffen unter Verwendung von waessrigen Suspensionen |
US3663402A (en) * | 1970-11-12 | 1972-05-16 | Ppg Industries Inc | Pretreating electrodepositable compositions |
US4529521A (en) * | 1983-08-26 | 1985-07-16 | The Dow Chemical Company | Method and apparatus for analyzing latexes |
-
1984
- 1984-08-25 DE DE19843431276 patent/DE3431276A1/de not_active Withdrawn
-
1985
- 1985-07-22 US US06/757,597 patent/US4639319A/en not_active Expired - Fee Related
- 1985-08-08 CA CA000488285A patent/CA1240272A/fr not_active Expired
- 1985-08-17 AT AT85110298T patent/ATE43369T1/de not_active IP Right Cessation
- 1985-08-17 EP EP85110298A patent/EP0172541B1/fr not_active Expired
- 1985-08-17 DE DE8585110298T patent/DE3570462D1/de not_active Expired
- 1985-08-23 JP JP60186517A patent/JPS6169837A/ja active Pending
- 1985-08-23 BR BR8504040A patent/BR8504040A/pt unknown
- 1985-08-23 ES ES546389A patent/ES8605008A1/es not_active Expired
- 1985-08-23 ZA ZA856438A patent/ZA856438B/xx unknown
- 1985-08-23 AU AU46598/85A patent/AU571106B2/en not_active Ceased
- 1985-08-23 MX MX206408A patent/MX168157B/es unknown
Non-Patent Citations (1)
Title |
---|
Ullmanns Encyklopädie der technischen Chemie, 4. Auflage (1978), S. 515, 516, 528-531 * |
Also Published As
Publication number | Publication date |
---|---|
EP0172541A1 (fr) | 1986-02-26 |
BR8504040A (pt) | 1986-06-10 |
ZA856438B (en) | 1986-04-30 |
JPS6169837A (ja) | 1986-04-10 |
DE3570462D1 (en) | 1989-06-29 |
MX168157B (es) | 1993-05-06 |
ES8605008A1 (es) | 1986-03-01 |
DE3431276A1 (de) | 1986-03-06 |
AU4659885A (en) | 1986-02-27 |
CA1240272A (fr) | 1988-08-09 |
ATE43369T1 (de) | 1989-06-15 |
US4639319A (en) | 1987-01-27 |
ES546389A0 (es) | 1986-03-01 |
AU571106B2 (en) | 1988-03-31 |
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