Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
2001-01-26
2002-09-10
Sanders, Kriellion A. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C524S086000, C524S156000, C524S165000, C524S198000, C524S315000, C524S319000, C524S371000, C524S375000, C524S386000, C524S387000
Reexamination Certificate
active
06448313
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to aqueous compositions which are useful for creating protective coatings on metallic substrates. The protective coating may be readily removed once the substrate has been formed or otherwise shaped.
BACKGROUND OF THE INVENTION
Many different goods are currently manufactured by drawing, pressing, bending or otherwise forming flat sheets of metal to the desired shape or configuration. In many cases, such metal sheets are finished with a decorative coating such as paint prior to forming. It will frequently be desirable to apply a temporary coating on top of the decorative coating in order to protect the decorative coating during forming, since forming may mar or otherwise damage the untreated decorative coating. Where the decorative finish is to be applied to the metal sheet after it is formed, temporary coating of the bare metal surface to protect it against corrosion or contamination will often be desirable. The development of temporary coatings which provide effective protection during forming, yet can be readily removed once forming is completed, thus would be of great value.
SUMMARY OF THE INVENTION
The present invention provides an aqueous composition comprising water, at least one polyvinyl alcohol, at least one surfactant and at least one corrosion inhibitor. In one embodiment of the invention, the aqueous composition has a mildly basic pH and is comprised of water, at least one polyvinyl alcohol, at least one surfactant (preferably a low foaming fluorinated, alkoxylated phenol or acetylenically unsaturated surfactant), at least two different corrosion inhibitors, and at least one coalescing solvent. A protective coating is obtained by applying the aforedescribed aqueous composition to a surface of a substrate (particularly a metallic substrate) and drying said aqueous composition. The dried coating protects the substrate surface, which may be bare or painted metal, during forming of the substrate. The protective coating is thereafter easily removed by a means such as peeling or rinsing with water.
DESCRIPTION OF THE INVENTION
The coating compositions of the present invention are aqueous in character. That is, water is used as the primary or predominate solvent or carrier for the other components of the coating composition. Although organic solvents, particularly alkanolamines and coalescing solvents, may additionally be present (as will be explained in more detail later), such solvents are utilized at relatively low concentrations (e.g., less than about 10 weight percent total, preferably less than about 6 weight percent total).
One or more polyvinyl alcohols are included in the aqueous composition. Such resins are commercially produced by the hydrolysis of polyvinyl acetate. The properties of the aqueous composition as well as the properties of the protective coating obtained using the aqueous compositions of this invention may be varied as desired by adjusting the degree of hydrolysis and the molecular weight of the polyvinyl alcohol. The degree of hydrolysis, for example, may suitably range from about 80% to about 100%, preferably 85% to 95%. Number average molecular weight may suitably range from about 10,000 to about 100,000. It is unnecessary to react or otherwise modify the polyvinyl alcohol prior to use. In preferred embodiments of the invention, both the polyvinyl alcohol and the aqueous composition in general are substantially free of plasticizer.
Polyvinyl alcohols useful in the invention may be readily obtained from commercial sources, including Air Products and Chemicals Inc. (which sells polyvinyl alcohols under the trademark AIRVOL) and DuPont (which sells polyvinyl alcohols under the trademark ELVANOL). While the concentration of the polyvinyl alcohol in the aqueous composition is not believed to be particularly critical, typically concentrations of from about 2 to about 50 (preferably, about 5 to about 20) percent by weight (calculated on a solids basis) are utilized.
Other water-soluble and/or water-dispersable polymeric resins may optionally also be present in the aqueous composition, including, for example, acrylic resins, polyethylenimines, polyethylene oxides, polyvinyl pyrrolidones, polyacrylamides and the like. Polyvinyl alcohol is generally the predominate polymeric resin in the composition, however (i.e., at least 50% by weight of the polymeric resin component of the composition is comprised of polyvinyl alcohol).
One or more surfactants (surface active agents) are also incorporated in the aqueous composition to provide satisfactory spreading and leveling of the aqueous composition on the surface of the substrate being coated. The surfactant(s) promote wetting of the substrate surface and also help to stabilize the aqueous composition against phase separation during storage. Preferably, the surfactants selected for use are low foaming in order to minimize the formation of bubbles in the protective coating. Fluorinated surfactants, alkoxylated phenol surfactants, and acetylenically unsaturated non-ionic surfactants have been found to be particularly suitable for use. Suitable fluorinated surfactants may be of the non-ionic, anionic, or amphoteric type, including combinations or mixtures thereof. Nonionic fluorinated surfactants include perfluoroalkyl polyethers and fluoroaliphatic polymeric esters such as those, for example, described in U.S. Pat. No. 5,747,234, incorporated herein by reference in its entirety. Illustrative anionic fluorinated surfactants include fluoroaliphatic sulfates and fluoroaliphatic sulfonates such as those for example, described in U.S. Pat. No. 5,616,273, incorporated herein by reference in its entirety. Suitable amphoteric fluorinated surfactants include surfactants containing fluoroaliphatic groups, carboxyl groups and amine and/or amide groups such as those described in U.S. Pat. No. 4,069,244 (incorporated herein by reference in its entirety). Amine perfluoroalkyl sulfonates may also be used. Fluorinated surfactants useful in the present invention may be readily obtained from a number of commercial sources including Ciba-Geigy (under the trademark LODYNE), Minnesota Mining and Manufacturing (under the trademark FLUORAD), Elf Atochem (under the trademark FORAFAC) and E. I. duPont de Nemours (under the trademark ZONYL). Suitable acetylenically unsaturated non-ionic surfactants include surfactants containing at least one hydroxylated or alkoxylated acetylenically unsaturated hydrophobic moiety. Preferably, such surfactants contain two hydrophobic groups connected by an acetylenic linkage with hydroxyl as alkoxy (preferably, ethoxy) groups pendant near the acetylenic linkage. Each hydrophobic group connected with the acetylenic linkage preferably contains from 4 to about 10 carbon atoms. Surfactants of this type are available commercially from Air Products and Chemical Company under the trademark SURFYNOL.
Suitable alkoxylated phenol surfactants include those materials prepared by reacting a phenol such as an alkyl phenol (e.g., nonylphenol) with one or more epoxides such as ethylene oxide and/or propylene oxide. Surfactants of this type are available commercially from Hoechst, for example.
The precise amount of surfactant(s) used in the aqueous compositions of the present invention is not thought to be critical; the optimum concentration for a particular application may be readily determined by routine experimentation. Typically, however, surfactant levels of from about 0.05 to about 0.6 percent by weight (based on the weight of the aqueous composition) will be effective.
One or more corrosion inhibitors (substances capable of inhibiting the corrosion of a metallic substrate surface) are also present in the aqueous composition. Although any of such materials known in the surface treatment field may be employed, it has been found that the use of one or more alkanolamines in combination with one or more corrosion inhibitors other than alkanolamines is advantageous.
Suitable alkanolamines include those compounds containing at least one nitrogen atom and at least one h
Harper Stephen D.
Henkel Corporation
Sanders Kriellion A.
LandOfFree
Temporary protective coating compositions does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Temporary protective coating compositions, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Temporary protective coating compositions will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2856855