Coating processes – Restoring or repairing
Patent
1996-05-20
1999-02-16
Dudash, Diana
Coating processes
Restoring or repairing
427142, 427379, 427421, 4274071, B05D 136, B05D 102, B05D 302
Patent
active
058718095
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a process for the preparation of a multicoat refinish, in which applying a surfacer and/or filler material, application, which contains metallic pigments and/or effect pigments, basecoat, and temperatures of up to 140.degree. C., preferably at temperatures below 100.degree. C. and particularly preferably at temperatures of from 60.degree. to 80.degree. C.
BACKGROUND OF THE INVENTION
The substrates suitable for refinish are either an old finish (production-line finish or repair finish), new parts which have been primed (mostly by electrodeposition, especially in the area of the finishing of heavy goods vehicle bodies), and also steel, aluminum, zinc plate or plastic. The choice of suitable coating materials and the process employed for the preparation of a refinish are determined by the surface to be finished and by the requirements of the customer.
A multicoat refinish is conventionally prepared by thorough cleaning of the damage site, sanding, treatment, if desired, with a surfacer and application of a repair filler to the area to be coated. In the case of all-over finishes, the entire old finish to be coated is pretreated analogously. Subsequently the area pretreated in this way is finished.
In this context, however, the preparation of metallic refinishes is a particular problem, because the color and brightness of the effect depend heavily on the manner of processing. Decisive factors at play here include the nozzle width of the spray gun and the spray pressure. The nature of dilution and the spray viscosity also influence color and effect. Especially when using aqueous basecoat compositions, clouding and similar effects are often observed.
The object of the present invention was therefore to provide a process for the preparation of a refinish having a very good quality, even in the case of critical colors. This means that changes in color, clouding and the like are to be avoided.
SUMMARY OF THE INVENTION
This object is surprisingly achieved by a process of the type mentioned in the FIELD OF THE INVENTION section, which is characterized in that in step (2) of the process the aqueous basecoat composition is applied such that pretreated area of the old finish until a boundary is reached, spray pass with the aqueous basecoat composition, finish which adjoins the previously coated region of the old finish, again until a boundary is reached, and is provided with a basecoat.
Surprisingly, using the process according to the invention it is possible to obtain refinishes in which the problems that usually occur are avoided or at least sharply reduced. In particular, the clouding which is frequently observed in the conventional refinish processes is avoided. In this context, it is significant that these outstanding results can also be achieved while using aqueous metallic basecoats. A further advantage is the saving in time brought about by the fact that there is only a brief flash-off time and, particularly preferably, no flash-off time at all between the first and second spray pass.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
This process according to the invention for the preparation of a multicoat refinish can be applied to a wide variety of substrates. In this context, it is irrelevant whether the systems to be provided with the refinish are conventional or are water-dilutable.
In order to carry out the process according to the invention, the old finish is first prepared to receive the refinish. Conventionally, for this purpose, the old finish is first thoroughly cleaned, for example with a silicone stripper, and roughened with abrasive paste or sandpaper. Thereafter, the area pretreated in this way is conventionally cleaned again and degreased. In addition to this, however, it is also possible to precoat the old finish, for example, using a solution of adhesion promoter. This preparation of the old finish, however, is known and therefore requires no further description.
If desired, the appropriately pretreated old finish can then have applied to
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Kortwinkel Herbert
Liedtke Hermann
BASF Lacke & Farben AG
Dudash Diana
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