Patent Application
20250179679
The invention relates to a method for dip bath treatment of a component in accordance with the claims.
Adequately known already from the prior art are methods for coating a component. In these methods, for example, a coating material and/or wax and/or polyvinyl chloride (PVC) is applied, especially in multiple coats, to a surface of the component. The coating material may be intended in particular for providing the component with protection from corrosion in the context of cathodic deposition coating (CDC). The coating is subsequently dried and in the process undergoes curing. The coating material, which may be referred to more particularly as a CDC, is a first coat on the component, for example. Atop the first coat, for example, a topcoat and/or a clearcoat may be applied. In particular, the coating may be applied to the component as the first coat in a coating system and be baked before coating continues.
It is an object of this disclosure to provide a method for dip bath treatment of a component so that curing of a coating applied to a surface of the component can be particularly improved.
This object may be achieved in accordance with this disclosure by a method for dip bath treatment of a component with the features of the independent claim. Advantageous configurations of the invention are subjects of the dependent claims and of the description.
A first aspect of the technology relates to a method for the dip bath treatment, more particularly for the surface treatment, of at least one component, more particularly for a motor vehicle, wherein at least one coating applied to at least one surface of the component via electrophoretic deposition, more particularly via cathodic deposition coating (CDC), is dried, more particularly at least partially or completely. The coating comprises, for example, coating material, more particularly a lower-most coat.
Wax and/or polyvinyl chloride (PVC) may be applied to the coating, for example, especially at the end of an operation of coating the component.
The method may comprise application of the coating via electrophoretic deposition, more particularly via cathodic deposition coating. This means that the coating can be applied, directly in particular, to the surface of the component via electrophoretic deposition, more particularly via cathodic deposition coating. The coating applied to the surface of the component can be subsequently dried, more particularly cross-linked or cured.
The component is formed, for example, of at least one metal. The component may therefore be a metallic component. The surface is therefore embodied for example as a metallic surface.
The coating, more particularly the coating material, may be understood in particular to be a liquid coating material. The coating applied to the surface of the component is dried, for example, via a dryer installation referred to more particularly as a dryer, and in the process may undergo preferably curing or chemical cross-linking. Here, the coating may transition from a liquid state into a solid state. The drying is therefore accompanied preferably by the curing, and more particularly the chemical cross-linking.
With electrophoretic deposition, more particularly with cathodic deposition coating, colloidal particles can be deposited, especially under the influence of an electrical field, on an electrode, more particularly on the component or the surface. The deposition may take place through an increase in pH on the component surface as a consequence of hydrogen deposition. For this, the component may be submerged at least partially, more particularly completely, into a dip tank filled with a fluid. Here, the component, more particularly the surface, as a consequence of submersion into the fluid, may be coated—i.e., provided at least partially, more particularly completely, with the coating referred to more particularly as a CDC coating. The coating may comprise at least one polymer resin and/or at least one binder and/or pigments and/or at least one solvent. With the coating, the fluid preferably comprises the coating material, and the coating can be applied to the component, more particularly to the surface, as a consequence of the submersion of the component into the dip tank or into the fluid. The coating is intended preferably as corrosion protection for the component, more particularly for the surface. The method may be referred to more particularly as a method for coating the surface of the component.
To be able to particularly improve the curing, more particularly the chemical cross-linking, of the coating applied to the surface of the component, the disclosure provides for the application to the surface of the component of at least one catalyst for the curing, more particularly for the chemical cross-linking, of the coating that takes place during drying. The application of the at least one catalyst to the surface may take place with in particular a locally uneven distribution, and at least indirectly or directly. Expressed in other words, a first amount of the catalyst may be applied to the surface, especially at least indirectly or directly, in a first subregion of the surface of the component, more particularly specifically, and a second amount of the catalyst, different from the first amount, preferably higher relative to the first amount, may be applied, more particularly directly, to the surface in a second subregion of the surface of the component, which is different from the first subregion. This means that during the drying, more particularly immediately at the start of the drying, of the coating, the catalyst is located, especially locally, with an uneven distribution on the surface, more particularly on or in the coating. The catalyst is therefore applied with specifically, more particularly, a locally uneven distribution in such a way, especially at least indirectly or directly, to the surface of the component that during the drying, or immediately at the start of the drying, of the coating, the first amount of the catalyst is located in the first subregion of the surface, more particularly on or in the coating, and the second amount of the catalyst is located in the second subregion of the surface, more particularly on or in the coating. Again in other words, the catalyst is specifically applied to the surface of the component in such a way that a local distribution of a concentration of the catalyst on the surface, more particularly on or in the coating, is not constant and therefore more particularly is locally variable or varies locally. Accordingly, for example, on the first subregion of the surface, more particularly in or on the coating, there is a first concentration of the catalyst, and on the second subregion of the surface, more particularly in or on the coating, there is for example a second concentration of the catalyst that is different from the first concentration, preferably higher relative to the first concentration.
For example, in the first subregion of the surface of the component, the first amount of the catalyst is applied to the surface, more particularly specifically, and more particularly at least indirectly or directly, in solution in the fluid or together with the fluid. The fluid may be referred to more particularly as CDC liquid. For example, the coating already comprises the catalyst, with the catalyst being applied subsequently, more particularly in the form of an additional amount of catalyst, to the surface, more particularly in or to the coating, with specifically an uneven distribution.
For example, the catalyst may be intended to particularly lower a temperature, referred to more particularly as the cross-linking temperature, for producing, more particularly for initiating, the chemical cross-linking of the coating. This means that the curing, more particularly the cross-linking, of the coating is producible or initiatable at least partially by the catalyst. The catalyst comprises a bismuth compound, for example. The catalyst may therefore be referred to more particularly as a bismuth catalyst. This means that a material of which the catalyst is formed comprises at least one chemical compound which is formed at least partially of bismuth.
The technology is based in particular on the following findings and considerations: With electrophoretic deposition, more particularly with cathodic deposition coating, a conflict of objectives may occur between visual constitution and cross-linking rate of the dried coating. The visual constitution may be referred to more particularly as the appearance. A particularly good visual constitution of the coating may be produced after the electrophoretic, more particularly cataphoretic, deposition by means of particularly slow drying, more particularly cross-linking, of the coating. In this case, for example, a particularly effective curing or cross-linking profile can be ensured. This means that for achieving the particularly good visual constitution, a timespan in which the coating—which as a liquid can still flow before the coating becomes solid, more particularly with catalytic assistance—is dried and the component is located for example in the dryer installation, referred to more particularly as an oven, can be particularly high. A particularly long oven time in which the component is located, for example in the dryer installation or is dried via the dryer installation, however, may result in particularly low reactivity in the cross-linking of the coating, referred to more particularly as coating material. The reactivity of the coating, more particularly of the coating material, may be controlled by the catalyst used—for example, by way of the chemical nature thereof and/or by way of the concentration thereof in the coating. At subregions of the surface of the component, more particularly those referred to as critical subregions, the particularly low reactivity of the coating may negatively impact the curing, more particularly the cross-linking, of the coating, since the critical subregions, especially in the dryer installation, may have a particularly slow heating rate. The critical subregions may for example be respective inner faces of a rocker of a motor vehicle—an electric vehicle for example (NCAR). The critical subregions of the surface do not reach, for example, the temperatures or hold times that are necessary for complete curing, more particularly cross-linking, of the coating. Thus, in a conventional method—for example, after the drying of the coating, referred to more particularly as CDC dryer traversal—the coating cannot be completely cured and hence the corrosion protection that exists cannot be sufficient. With the conventional method, the concentration of the catalyst is customarily at the same level before and after the deposition of the coating, more particularly the coating material, at all points on the surface of the component. This means that with the conventional method, the catalyst is not applied with a specifically uneven distribution to the surface, but instead with an even or uniform distribution. With the conventional method, therefore, the degree of cross-linking of the coating may be dependent in particular on the temperature attained during drying. As a result of this temperature dependence of the degree of cross-linking with the conventional method, inhomogeneous cross-linking may occur at different points or subregions of the surface of the component, particularly when substrate temperature curves are different in each case.
By way of contrast, the method of this disclosure allows the curing, especially the cross-linking, of the coating to be particularly improved. Through the specifically unevenly distributed application of the catalyst to the surface of the component, the concentration of the catalyst, referred to especially as catalyst concentration, especially in the coating, can be increased locally. As a result, a particularly increased catalyst activity can be produced for particularly rapid curing, especially for particularly rapid cross-linking, of the coating at points of the component, for example, such as the critical subregions which only attain particularly low temperatures during drying, especially in the dryer installation, for example. This means that the respective amount of the catalyst in the respective subregions can be specifically adjusted, especially in line with requirements. Consequently, the reactivity or the cross-linking rate can be locally specifically adjusted and thereby particularly increased, in particular. Applying a relatively large amount of the catalyst to the complete surface of the component can customarily adversely influence the visual constitution, in the form of waviness in the coating, for example. This can be avoided through the specifically unevenly distributed application of the catalyst to the surface. As a result, the visual constitution, more particularly a surface quality, of the surface of the component can be particularly increased. Alternatively, a deterioration in the visual constitution of the surface as a result of the increased catalyst concentration may be accepted at, for example, points on the surface of the component that are not in the field of view, especially of a customer for the motor vehicle. In particular, via the method of this disclosure, corrosion resistance of the surface of the component can be particularly increased. This means that component lifetime can be particularly increased.
The catalyst may be introduced onto or into the coating with specifically, especially locally, an uneven distribution, in pure form or in solution, especially in a suitable solvent, or as a suspension. This means that the catalyst can be introduced selectively into the CDC material. As a result, the catalyst concentration can be particularly increased locally in individual, especially selected, surface regions of the surface.
In a further configuration, the unevenly distributed, more particularly local, application of the catalyst to the surface of the component is carried out before application of the coating. Expressed in other words, the catalyst is applied with specific uneven distribution to the surface of the component before the coating is applied. This means that first the catalyst can be applied with specific uneven distribution to the surface and subsequently the coating can be applied to the surface or to the catalyst. The catalyst may therefore be applied, especially as a solution or as a suspension, to the surface of the component that is to be coated, before the coating, more particularly the CDC coating material, is deposited. As a result, the catalyst can be applied to the surface in a particularly advantageous manner, especially with particularly little cost and complexity. The cost and complexity of production, especially the production costs, for the component can in this way be kept particularly low, for example.
It is preferred here for the catalyst to be applied with specific uneven distribution directly to the surface, more particularly the metallic surface, of the component. This means that the catalyst is applied with a specifically uneven distribution and directly to the surface to be coated before the coating. As a result, the catalyst can be applied to the surface with particularly little cost and complexity.
Alternatively or additionally, the unevenly distributed, more particularly locally unevenly distributed, application of the catalyst is carried out after application of the coating. Expressed in other words, after the application of the coating, the catalyst is applied with specifically, more particularly locally, uneven distribution to the surface, more particularly to the coating. This means that the coating is applied to the surface and subsequently the applied coating is provided with the catalyst. The catalyst may therefore be applied in the form for example of a solution or a suspension, after the electrophoretic or electrolytic deposition, to a coating surface, more particularly coating material surface, which in particular is still wet. The wet coating surface may be referred to more particularly as “wet CDC”. As a result, the catalyst can be applied to the surface in a particularly advantageous way, especially with particularly low cost and complexity. In particular, detachment of the catalyst from the surface during the coating of the surface with the coating can be avoided. Therefore, in particular, leaching of the catalyst into the dip tank and more particularly the accumulation of or increase in the concentration of catalyst in the dip tank can be avoided.
Preferentially, for the application of the coating, the component is submerged into a dip tank filled with a fluid. Expressed in other words, the fluid is accommodated in the dip tank, with the component being immersed into the dip tank or into the fluid at least partially, more particularly completely, so causing the coating present in the fluid, more particularly in liquid form, to be applied to the surface of the component. The fluid is therefore, for example, a mixture which comprises the coating. For example, the fluid may comprise water or the fluid may be water.
The catalyst is preferably present in the fluid. This means that the dip tank is filled with a mixture which comprises the fluid and the catalyst. The fluid may alternatively be a mixture which comprises the catalyst. Preferably, because the catalyst is present in the fluid, the catalyst is applied in a first coat, in particular with even distribution, to the surface during application of the coating by the submersion of the component, more particularly the surface of the component, into the fluid. Expressed in other words, as a consequence of the submersion of the component, especially the surface, into the fluid, the catalyst is applied in the first coat to the surface, with the amount of catalyst applied in the first and second subregions being the same in each case. This means that the concentration of the catalyst on the surface of the component or in the coating in the first coat has a locally identical distribution or is constant. Again in other words, the coating already comprises the catalyst, in particular with even distribution. As a result, the catalyst can be applied to the surface with particularly little cost and complexity. Therefore, for example, production costs for the component can be kept particularly low. The first coat here may be understood more particularly to be a primary coat, more particularly a primary concentration, of the catalyst.
Preferably, during the—more particularly locally—specifically unevenly distributed application, the catalyst is applied to the surface, more particularly applied or introduced to or into the coating, in a second coat, which is different from the first coat. This means that the catalyst in the first coat is applied with an even distribution to the surface and in the second coat is applied with specifically an uneven distribution to the surface of the component. In other words, the coating already comprises the catalyst, more particularly with even distribution, especially in a lower concentration relative to the second coat, with the catalyst being subsequently applied in the second coat to increase the concentration, more particularly the local concentration. The first coat may be applied before the second coat or after the second coat. The first coat may be referred to in particular as the even coat and the second coat may be referred to in particular as the uneven coat. The respective catalyst applied in the first coat and in the second coat preferably comprises the same catalyst, in other words the same catalyst material. This means that in the fluid, especially in the CDC tank material, in the dip tank, the catalytically active substance used is the same as for the specifically unevenly distributed application to the surface. As a result, the catalyst can be applied to the surface with particularly little cost and complexity. Especially when the second coat is applied before the first coat to the surface, any—in particular, minimal—entrainment or “bleeding” into the fluid of the catalyst applied with the second coat to the surface of the component, when the component is submerged into the dip tank, can be untroublesome, particularly in light of the fact that the catalyst applied to the surface in the second coat is not a foreign substance, as the catalyst for the application of the first coat is present in the fluid.
For the drying of the coating, the component, more particularly the surface, is preferably exposed to a fluid stream, more particularly to an air stream. Expressed in other words, during the drying of the coating, a fluid, more particularly air, is caused to flow around and/or against the component, more particularly the surface. This allows particularly effective curing, especially cross-linking, of the coating. The fluid stream may be generated by means of a fan of the dryer installation, for example. The fan may be referred to in particular as a blower or as an aerator.
For the drying of the coating, the component, more particularly the surface, is preferably heated. Expressed in other words, heat is supplied to the component, more particularly the surface, during drying of the coating. This allows the coating to be particularly effectively cured, especially cross-linked. For example, the dryer installation features a heating installation by means of which the component, more particularly the surface, is or becomes heatable. For example, the component may be heated directly via the heating installation or the fluid stream may be heated by the heating installation, thus allowing the component, more particularly the surface, to be heated by means of the heated fluid stream.
In the context of the drying or the curing, provision may be made for at least one drying temperature, referred to more particularly as curing temperature, and at least one timespan in which the drying or the curing takes place. Here, preferably, a criterion, more particularly a mandated criterion, is to be met with regard to the drying temperature and the timespan, which may be interpreted in particular to mean that the drying temperature and the timespan are specifically chosen in such a way that the drying or the curing can be carried out in a particularly advantageous manner.
In a further configuration, the component on whose surface the coating applied via electrophoretic deposition, more particularly via cathodic deposition coating, is dried is embodied as a bodyshell part of a bodyshell for a motor vehicle. This means that the component comprises the bodyshell part of the bodyshell. The method may therefore be understood in particular as being a method for the dip bath treatment of the body shell part. Expressed in other words, the coating applied to the surface of the bodyshell part via electrophoretic deposition, more particularly cathodic deposition coating, may be dried. In particular, the catalyst for the curing that takes place during drying, more particularly for the chemical cross-linking, of the coating may be applied to the surface of the bodyshell part with specifically, more particularly locally, an uneven distribution, more particularly at least indirectly or directly. The coating applied to the bodyshell part can be cured particularly effectively as a result. Corrosion resistance of the bodyshell part can be particularly increased as a result.
The bodyshell may be understood in particular as a body of the motor vehicle. The body is embodied preferably as bodywork, more particularly self-supporting bodywork, of the motor vehicle. The bodyshell part may for example comprise an assembly or comprise a component, referred to more particularly as a bodywork component, of the bodyshell. The bodyshell part, more particularly the component, may be embodied as a single piece or multiple pieces. The motor vehicle is embodied preferably as a powered vehicle, more particularly as a powered vehicle for individuals or as a powered utility vehicle or load-carrying vehicle.
Further features of the invention are apparent from the claims, the figures, and the description of the figures. The features and feature combinations stated above in the description and also the features and feature combinations shown below in the description of the figures and/or in the figures alone can be used not only in the particular combination indicated but also in other combinations, or on their own.
The invention is now elucidated in more detail with reference to a preferred working example and with reference to the drawings.
Elements in the figures which are identical or functionally identical bear identical reference signs.
In the method, preferably, a coating 5 is applied, especially directly, to a surface 4 of the component 2 via electrophoretic deposition 3, more particularly via cathodic deposition coating (CDC). The coating 5 here is applied to the surface 4 preferably via a dipping operation. For the application of the coating 5, the component 2, more particularly the surface 4, is preferably submerged into a dip tank 7 filled with a fluid 6.
The coating 5 applied to the surface 4 of the component 2 via electrophoretic deposition 3, more particularly via cathodic deposition coating, is dried via a dryer installation, for example. This may be referred to in particular as drying 8 of the coating 5.
To be able to improve curing 9, more particularly chemical cross-linking, of the coating 5 applied to the surface 4, a catalyst 10 for the curing 9, more particularly cross-linking, of the coating 5 that takes place during the drying 8 is applied with a specifically uneven distribution to the surface 4 of the component 2. This means that, for example, a first amount of the catalyst is applied to a first subregion 11 of the surface 4 of the component 2, and a second amount of the catalyst, different from the first amount, is applied to a second subregion, different from the first subregion 11, of the surface 4 of the component 2. Accordingly, during the drying 8 or immediately at the start of the drying 8 of the coating 5, the first amount of the catalyst 10 is located in the first subregion 11, for example, and the second amount of the catalyst 10 in the second subregion 12. Consequently, through selective deployment of catalyst, the coating 5, more particularly the curing 9 or cross-linking of the coating 5, can be particularly optimized, especially through inhomogeneous catalyst distribution. Hence it is possible, for example, for points on the surface which only attain particularly low temperatures during drying, to have a particularly high catalyst concentration, for example, hence allowing particularly rapid cross-linking of the coating 5 to be produced, especially locally. As a result, particularly effective, more particularly even, curing 9, more particularly cross-linking, of the coating 5 can be enabled. Corrosion resistance of the component 2, especially at the surface 4, can be particularly increased as a result.
The subregions 11, 12 may follow one another at least indirectly, more particularly directly. The subregions 11, 12 may be spaced apart from one another.
In the working example shown in
Alternatively or additionally, the unevenly distributed application of the catalyst 10 may be carried out before application of the coating 5. In this case, preferably, the catalyst 10 is applied directly, with a specifically uneven distribution, to the surface 4, more particularly the metallic surface 4, of the component 2.
In a further configuration, the catalyst 10 is present in the fluid 6, and so during application of the coating 5, the catalyst 10 is applied to the surface 4, in particular with an even distribution, in a first coat 13 through the submersion of the component 2, more particularly the surface 4, into the fluid 6. This means that the first coat 13 of the catalyst 10 is applied to the surface 4 together with the coating 5. This may be interpreted in particular to mean that the catalyst 10, particularly the first coat 13, is present in the coating 5. During the specifically unevenly distributed application of the catalyst 10 to the surface 4, the catalyst 10 is applied to the surface 4, more particularly to the coating 5 or to the first coat 13, in a second coat 14, which is different from the first coat 13.
The second coat 14 may be applied after the first coat 13 to the surface 4. The second coat 14 may therefore be applied to the first coat 13. Alternatively, the second coat 14 may be applied before the first coat 13 to the surface 4. The first coat 13, and especially the coating 5, may therefore be applied to the second coat 14.
In a further configuration, for the drying 8 of the coating 5, the component 2, more particularly the surface 4, is exposed to a fluid stream 15. Alternatively or additionally, for the drying 8 of the coating 5, the component 2, more particularly the surface 4, may be heated. This means that heat 16 is supplied to the component 2, more particularly the surface 4, for the drying 8 of the coating 5.
The component 2 is embodied for example as a bodyshell part 17 of a bodyshell for a motor vehicle. This means that the component 2 on whose surface 4 the coating 5 applied via electrophoretic deposition 3 is dried is embodied as a bodyshell part 17 of the bodyshell for a motor vehicle.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2022 113 626.4 | May 2022 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2023/062076 | 5/8/2023 | WO |
