Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – At least one aryl ring which is part of a fused or bridged...
Patent
1994-07-29
1996-04-23
Michl, Paul R.
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
At least one aryl ring which is part of a fused or bridged...
524406, 524183, 524147, 524398, C08K 310, C08K 551, C08K 504
Patent
active
055104100
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to an aqueous autodeposition coating composition in the form of an acidic coating composition (pH approximately 1.6 to 5) that contains water-dispersible or water-soluble organic film-forming resin, fluoride ion and/or complex fluoride ion, chromium ion (hexavalent chromium ion or hexavalent chromium ion+trivalent chromium ion), and tungstate ion and/or molybdate ion. This aqueous autodeposition coating composition is capable of forming a highly corrosion-resistant, strongly adherent resin film on metal surfaces when brought into contact with the surface of a metal, for example, a ferriferous metal, zinciferous metal, aluminiferous metal, magnesium-based metal, and so forth.
RELATED ART
Autodeposition coating compositions are acidic coating compositions that contain organic film-forming resin and that can form a resin film on a metal surface when brought into contact with the metal surface. Autodepositing coating compositions are disclosed in, for example,
Japanese Patent Publication Number Sho 47-17630 17,630/1972!,
Japanese Patent Publication Number Sho 48-14412 14,412/1973!,
Japanese Patent Publication Number Sho 52-21006 21,006/1977!,
Japanese Patent Publication Number Sho 52-35692 35,692/1977!,
Japanese Patent Publication Number Sho 53-15093 15,093/1978!,
Japanese Patent Publication Number Sho 53-16010 16,010/1978!,
Japanese Patent Publication Number Sho 53-44949 44,949/1978!,
Japanese Patent Application Laid Open Kokai or Unexamined! Number Sho 60-58474 58,474/1985!,
Japanese Patent Application Laid Open Number Sho 61-168673 168,673/1986!, and
Japanese Patent Application Laid Open Number Sho 61-246267 246,267/1986!.
A characteristic feature of the known coating compositions is their ability to lay down a resin film upon the immersion of a clean metal surface in the particular coating composition. Moreover, the coating film's thickness and weight increase with immersion time. In the case of these compositions, the chemical activity of the coating composition overlying the metal surface (metal ion eluted from the metal surface by etching induces association of the resin particles with resulting deposition on the metal surface) results in the efficient deposition of a resin film on the metal surface without the application, as in electrodeposition, of an external electrical source.
The demand for more simple processes (contraction) has been very strong in recent years with regard to the painting of metals, for example, as typified by coating lines for automobile bodies. However, in the autodeposition coating processes (painting) disclosed in U.S. Pat. No. 3,647,567, U.S. Pat. No. 4,030,945, Japanese Patent Publication Number Sho 53-15093, and Japanese Patent Application Laid Open Number Sho 61-168673, a rinse treatment with a chromium-containing solution or aqueous alkali solution, etc. (post-treatment directly after autodeposition) is implemented prior to film curing (prior to baking/drying) in order to provide an ultimately produced film with better corrosion resistance and better adherence.
One approach to process contraction would be the elimination of this rinse treatment step. However, elimination of the rinse treatment step leads to a substantial deterioration in film adherence and corrosion resistance and to a significant deterioration in film quality. In fact, not only is a simpler process required, but an even better performance is required of the film since the performance of the prior coatings has not been entirely satisfactory with regard to critical properties, particularly adherence and corrosion resistance. An important problem within the sphere of process contraction and coating performance is to achieve improvements in film adherence and corrosion resistance while at the same time omitting the rinse treatment prior to film cure.
The present invention takes as its object the introduction of a film which has a much better adherence and corrosion resistance than the films formed by prior-art coating compositions, but which is produc
Honda Takumi
Koga Mitsuyuki
Naito Kazuhisa
DeWitt LaVonda R.
Henkel Corporation
Jaeschke Wayne C.
Michl Paul R.
Ortiz Daniel S.
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