Coating processes – With pretreatment of the base – Organic base
Patent
1996-02-12
1998-05-12
Lusignan, Michael
Coating processes
With pretreatment of the base
Organic base
106 1413, 4273935, 510189, 510242, 510243, 510488, B05D 302
Patent
active
057501980
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a water-based liquid composition for treating plastics, particularly plastic moldings, more particularly those made of polypropylene, polyurethane, and the like, that are used, e.g., as body panels, bumpers, or the like in automobiles. The invention is especially suited to prepainting treatment of such plastics. The invention is accordingly described below primarily with reference to prepainting treatment for plastic moldings, but more generalized application to plastic surfaces is within the scope of the invention.
BACKGROUND ART
The plastic moldings used for automotive bumpers, etc., usually are currently manufactured by injection molding. In the case of resins that are prone to stick to the mold, such as polyurethane, the mold surface is usually coated prior to actual molding with a wax-based external release agent, and a metal soap (for example, zinc stearate), which functions as an internal release agent, is also frequently added to such resins in advance of molding. Various additives other than internal release agent often are also blended into resins for the purpose of improving the strength, improving paint adherence, improving the resistance to aging, and the like. As a result, during the molding process the strongly hydrophobic internal additives and of course any internal release agent bleed onto the surface to some degree. The presence on the surface of substances such as external release agent and bled-out internal additives impairs the post-painting adherence by the paint film and also causes paint crawling and thereby compromises the appearance of the paint film. The preparatory treatment that precedes painting must therefore not only remove contaminants adhering after molding, such as dust and oil, but must also remove substances such as external release agent and internal additives that have bled onto the surface.
The treatment of plastic moldings prior to painting has heretofore consisted mainly of the use of solvent cleaners such as 1,1,1-trichloroethane, freons, and the like. This type of treatment can dissolve and remove release agents and also has an excellent operating efficiency due to its ease of drying. However, as is well known, environmental considerations have made the development of substitute pretreatment methods a matter of urgency.
Cleaning with acidic and alkaline water-based cleaners and cleaning with emulsified solvent cleaners have been investigated as substitute pretreatment methods. These methods differ from solvent cleaning in that they require a rinse step and therefore require a drying step (see
However, even after release agent on the surface has been removed by cleaning, drying must be conducted at low temperatures since internal release agent and strongly hydrophobic internal additives bleed onto the surface during the drying step. This lengthens the drying time and thus necessitates the use of large-scale equipment. In addition, since internal release agents and strongly hydrophobic internal additives gradually bleed onto the surface even at room temperature, the paintability also becomes impaired when a lengthy period of time is allowed to elapse between cleaning and painting. This requires that the cleaned molding be promptly painted.
As described above, research has heretofore focused on the removal of internal additives once they have bled onto the surface of the plastic molding from within the molding; however, up to now in the knowledge of the applicants there have been no investigations into the inhibition of bleed-out by internal additives onto the surface.
DISCLOSURE OF THE INVENTION
Problems to Be Solved by the Invention
The present invention is directed to an inhibition of the surface bleed by internal plastic additives that occurs with elapsed time and during the drying step in the interval after the water-based treatment of plastic moldings preparatory to their painting. More specifically, the present invention takes as its objects an increase in the drying temperature in order thereby to support e
REFERENCES:
patent: 3404996 (1968-10-01), Deichert et al.
patent: 3481763 (1969-12-01), Hider et al.
patent: 3993575 (1976-11-01), Howanitz et al.
patent: 5167992 (1992-12-01), Lin et al.
patent: 5248525 (1993-09-01), Siebert
Furuyama Osamu
Hamamura Kazunari
Motozawa Masahiro
Henkel Corporation
Jaeschke Wayne C.
Lusignan Michael
Robbins Frank E.
Wisdom, Jr. Norvell E.
LandOfFree
Composition and process for prepainting treatment of plastics does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Composition and process for prepainting treatment of plastics, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composition and process for prepainting treatment of plastics will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-977413