Metal treatment – Process of modifying or maintaining internal physical... – Processes of coating utilizing a reactive composition which...
Reexamination Certificate
2002-10-18
2003-08-19
Green, Anthony J. (Department: 1755)
Metal treatment
Process of modifying or maintaining internal physical...
Processes of coating utilizing a reactive composition which...
C106S014120, C106S014150, C106S014440
Reexamination Certificate
active
06607610
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a composition and its use in forming corrosion inhibiting and adhesion promoting coatings on metal surfaces. More particularly, the present invention relates to water-soluble or water-dispersible polyphenolamine compositions and their use as metal treatment compounds.
BACKGROUND OF THE INVENTION
One means of minimizing the impact of corrosion on metal surfaces has been to coat the surface with paint. The paint acts as a barrier between the metal surface and the environment and thus helps prevent or at least minimize corrosion of the metal surface. However, one problem associated with this solution is that the paint does not always adhere properly to the metal surface. The result may be peeling, cracking, blistering, or flaking of the paint, thus rendering the substrate metal surface again subject to corrosion.
The need for applying protective coatings to metal surfaces for improved corrosion resistance and paint adhesion is well known in the metal finishing and other metal arts. One attempt to alleviate the problem for adhesion of paint to metal surfaces has been to subject the metal surface to a treatment which is known as phosphating, i.e., a process whereby a metal surface is treated with chemicals which form a metal phosphate conversion coating on the metal surface. Such a treatment typically assists in rendering the metal less subject to corrosive attack and, at the same time, in rendering the surface more suitable for application of a protective coating such as paint. The resulting bond between the metal surface and the paint is thus greatly improved. However, phosphate baths require that precise formulations be maintained and that the process procedures and conditions of operation be controlled within narrow limits. The phosphating process also requires that the metal surface be given two rinses subsequent to the phosphating bath, the first being a water rinse and the second being a passivating solution rinse which further enhances the corrosion resistance and adhesion characteristics of the coating. Traditionally, conversion coated metal surfaces have been given a second rinse with a solution containing a hexavalent chromium compound.
Lindert, U.S. Pat. No. 4,433,015 teaches that because of the toxic nature of hexavalent chromium compounds, expensive treatment equipment must be used to remove chromates from effluent water to prevent pollution of rivers, streams and drinking water sources. Hence, in recent years there have been research and development efforts directed to discovering effective alternatives to the use of such post-treatment solutions. Lindert teaches that an alternative to the hexavalent chromium compound is a polymer having phenol groups attached along an ethylenic polymer backbone. The phenol groups may have an amine substituent, which may further comprise hydroxy-alkyl groups. The polymer, made water-soluble through neutralization of the amine moiety with organic acid, may be employed in an acidic or basic solution. It is also taught by Lindert that the solution, in addition to being used as a post-phosphate rinse, may be used to treat previously untreated metal surfaces including aluminum and zinc.
Frank et al., U.S. Pat. No. 4,466,840 teaches that there is a need for a simple means to achieve results similar to that obtained with a phosphatizing process without the complexity of such a treatment. As an alternative to such a phosphatizing treatment, Frank et al., proposes employing hydroxybenzylamines, preferably in an aqueous solution, to produce coatings on metal surfaces, which coatings act as corrosion inhibitors and adhesion promoters. The amine moiety of the hydroxybenzylamines comprise secondary amines having alkyl substituents.
Siegl et al., U.S. Pat. Nos. 4,790,878 and 4,830,680 teaches the use of unique diphenolamines in an aqueous acidic solution useful to deposit an adhesion promoting and corrosion inhibiting coating on metal surfaces.
Siegl et al., U.S. Pat. Nos. 4,770,727 and 4,840,667 further teach the use of unique diphenolamine oligomeric metal-chelating compounds useful to deposit an adhesion promoting and corrosion inhibiting coating on metal surfaces. These compositions, in which the mole ratio of amine reagent to phenol reagent is 1:2, are compositionally different than the compositions of the present invention.
SUMMARY OF THE INVENTION
The present invention is directed to new polyphenolamine compounds and their use as corrosion inhibiting and adhesion promoting treatments for metal surfaces. The polyphenolamine compounds of the present invention are prepared via any suitable route, preferably via the Mannich reaction of a phenol, an aldehyde and a mixture of amines. The polyphenolamine compounds of the present invention are water-soluble or water dispersible compounds. The most preferred compound is prepared via the Mannich reaction of p-cresol, formaldehyde and a mixture of ethanolamine and polyetheramine. The polyphenolamine compounds of the present invention have been found to be particularly effective at depositing an adhesion promoting and corrosion inhibiting coating on a metal surface.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention is directed to new polyphenolamine compounds and their use in treating metal surfaces to enhance the corrosion resistance and adhesion properties thereof. The compound comprises a water-soluble or water-dispersible compound selected from compounds having the general chemical formula:
A—L—POH—[—L—A—L—POH—]
x
—L—A Formula 1
wherein segments “A” (amine), “L” (aldehyde), and “POH” (phenolic compound) are formed by reaction of the amine, aldehyde, and phenolic compound, for a time and under conditions sufficient to form a polyphenolamine of Formula 1. This synthesis technique is known to those skilled in the art as being exemplary of the Mannich reaction.
The segment “A” in Formula 1 is the unit formed after reaction of one or more amines. Exemplary amines encompassed by “A” include, but are not limited to, substituted or non-substituted C
1
-C
18
alkyl or aryl primary and secondary amines, such as ethanolamine, benzylamine, laurylamine, 2-(methylamino)ethanol, allylamine, and (aminomethyl)phosphonic acid; aminoacids, such as glycine, alanine, glucosamine, and iminodiacetic acid; polyetheramines, such as the Jeffamine® series of products commercially available from Huntsman Corporation; mixtures of any of the foregoing and the like; with the proviso that “A” is not encompassed entirely of secondary amines.
The segment “L” in Formula 1 is the unit formed after reaction of one or more aldehydes. Exemplary aldehydes encompassed by “L” include, but are not limited to, formaldehyde, benzaldehyde, mixtures of any of the foregoing and the like. The formaldehyde utilized in the reaction may be either an aqueous solution optionally stabilized with methanol, an alcoholic solution, or paraformaldehyde.
The segment “POH” in Formula 1 is the unit formed after reaction of one or more phenolic compounds. Exemplary phenolics encompassed by “POH” include, but are not limited to, phenolic compounds that possess at least two reactive sites, such as cresol, nonylphenol, catechol, resorcinol, mixtures of any of the foregoing and the like. As would be understood by one skilled in the art in view of the present disclosure, it is intended that such phenolic compounds contain at least two sites that would be susceptible to the Mannich reaction.
The molar ratio of A:L:POH may fall within the range of 1:1:1 to 1.5:2:1. In this regard, the molar percentage of “A”, “L”, and “POH” must add up to 100%.
In a preferred embodiment of the invention the polyphenolamine compound for treating metal surfaces to enhance the corrosion resistance and adhesion properties thereof is represented by the following formula:
wherein R
1
is a substituted or unsubstituted C
1
-C
18
alkyl or aryl, CO
2
M, SO
3
M, or mixtures thereof; M is hydrogen, a water-soluble cation, or mixtures thereof; x is 1-100; R
2
is hydrogen, a substituted or unsubs
Carey William S.
Haberle Bruce
Lue Ping
Melzer Jeffrey I.
Rodzewich Edward A.
Duane Morris LLP
GE Betz, Inc.
Green Anthony J.
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