Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
1997-12-19
2001-01-23
Beck, Shrive (Department: 1762)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S3550AC, C428S421000, C428S422000, C428S914000, C156S071000, C156S094000, C156S304300
Reexamination Certificate
active
06177189
ABSTRACT:
TECHNICAL FIELD
The present invention relates to paint replacement films, especially corrosion protection surface coatings in the form of appliqu{acute over (e)}s. The appliqu{acute over (e)}s preferably include a protective film, preferably an elastomer, as a topcoat backed with a vapor barrier that is adhered to a substrate, like the exterior of an aircraft.
BACKGROUND ART
Painting has long been the process of choice for applying coatings to surfaces especially those having complex curvature. Painting is generally a controllable, reliable, easy, and versatile process. The paint can include additives to give the surface desired physical properties, such as gloss, color, reflectivity, or combinations thereof. The painting process is well understood and produces quality coatings having uniform properties even when the surface includes complex curvature. Unfortunately, painting is falling under closer environmental scrutiny because they use volatile solvents to carry the pigments or because of the pigments themselves. Therefore, there is a need to replace the painting process with a process that has less environmental impact. Furthermore, while painting is well defined, well understood, and common, it remains an “art” where masters produce better products than novices or apprentices without necessarily being able to account for why or to teach others how.
Painted surfaces sometimes lack the durability that quality-conscious customers demand. The surface must be treated and cleaned prior to applying the paint. The environment surrounding the part must be controlled during the coating application, often requiring a spray booth, Painted coatings are also vulnerable to damage like cracks or scratches. Isolated damage may require the repair of a large area, such as forcing the repainting of an entire panel.
Spraying inherently wastes paint and is unpredictable because of the “art” involved with the application. Improper application cannot be detected until the spraying is complete, then rework to correct a defect usually affects a large area even for a small glitch.
U.S. Pat. No. 4,986,496 by Marentic et al. describes a drag reduction article in the form of a conformable sheet material (a decal) with surface texturing for application to aircraft flow control surfaces to reduce aircraft drag. The material fits on curved surfaces without cracks, bubbles, or wrinkles because of the paint-like properties of the basic carrier film. Marentic's decals are manufactured flat and are stretched to the intended simple curvature. Stretching can be problematic over time if the stretched material shrinks to expose a gap between adjacent decals where weather can attack the decal-surface interface. Stretching generally limits Marentic appliqu{acute over (e)}s to surfaces of slowly changing curvature. We incorporate this patent by reference.
Appliques (i.e. decals) are also described in U.S. Pat. No. 5,660,667 Davis, which we incorporate by reference. Having complex curvature, the appliqu{acute over (e)}s form complete, bubble-free, wrinkleless coverings on surfaces of complex curvature without significant stretching. Davis applies these appliqu{acute over (e)}s by:
(a) analyzing and mapping the Gaussian curvature of the surface to be covered to identify lines of constant Gaussian curvature;
(b) identifying geodesic lines on the surface, such that the lines of constant Gaussian curvature and the geodesics form a mapping grid on the surface;
(c) analyzing the stretchiness needed to blend between appliqu{acute over (e)}s of adjacent areas of different Gaussian curvature;
(d) producing appliqu{acute over (e)}s for each Gaussian curvature using a family of molds;
(e) identifying on the surface the grid made up of the lines of constant Gaussian curvature and intersecting geodesics; and
(f) applying appliqu{acute over (e)}s of a particular Gaussian curvature along the matching line of constant Gaussian curvature on the surface to produce a complete, bubble-free, wrinkleless covering on the surface comparable to a conventional painted coating and while minimizing stretching of any appliqu{acute over (e)} to complete the coating.
Identifying the grid can include physically marking the lines, displaying them with an optical template, or simply defining them in a 3-dimensional digital data model for the surface.
The Davis method recognizes that surfaces having the same Gaussian curvature can be mapped topologically to correspond. If you have a surface of Gaussian curvature 5 ft
−2
, for example, instead of making a “splash” mold of the surface to make appliqu{acute over (e)}s, you mold appliqu{acute over (e)}s to curvature 5 ft
−2
on a master curvature 5 ft
−2
mold, which, for example, might be a sphere. Appliqu{acute over (e)}s from the master mold will fit bubble-free and wrinkleless on the actual surface.
Often surfaces must be protected against corrosion. Such protection commonly involves surface treatments or primers (i.e. chromated primers or conversion coatings) that are relatively expensive because of the chemicals involved and the time associated with their application. These traditional coatings are relatively heavy, especially when coupled with other surface coatings that must be applied over the corrosion protection coating to provide color, gloss, enhanced surface durability, abrasion protection, a combination of these attributes, or other attributes. The chemicals used in conventional corrosion protection coatings often are hazardous materials.
Appliqu{acute over (e)}s are of considerable interest today for commercial and military aerospace applications. Lockheed Martin and 3M are conducting flight tests on paintless aircraft technologies. These appliqu{acute over (e)}s (like ours) save production costs, support requirements, and aircraft weight while providing significant environmental advantages. The Lockheed Martin appliqu{acute over (e)}s are described in greater detail in the article: “Paintless aircraft technology,” Aero. Eng'g, November 1997, p. 17, which we incorporate by reference. Commerical airlines, like Western Pacific, use appliqu{acute over (e)}s to convert their transports into flying billboards. We seek durable appliqu{acute over (e)}s that can replace conventional military or commercial aviation paint systems to reduce lifecycle costs, improve performance, and protect the underlying surfaces from corrosion.
SUMMARY OF THE INVENTION
The present invention combines a surface coating via an array of appliqu{acute over (e)}s with a vapor barrier to provide corrosion protection. The appliqu{acute over (e)}s may provide adequate corrosion protection to eliminate altogether conventional surface corrosion protection treatments, thereby, saving weight and reducing environmental concerns. Alternatively, the combination of appliqu{acute over (e)} corrosion protection with environmentally friendly but relatively inferior, chromate-free conversion coatings may replace the environmentally sensitive, traditional corrosion protection techniques (i.e., chromated conversion coatings and primers).
Corrosion on metal surfaces or around metal fasteners in resin composite structures produces oxidation that reduces the surface quality and that frequently can make the structural integrity suspect. Maintenance to correct corrosion or to ensure that it does not occur is costly because it is labor-intensive. A more reliable corrosion protection system would find widespread acceptance in commercial and military aerospace.
In addition to the corrosion protection, the vapor barrier can be beneficial on aerospace structure to limit the migration of water through a structure. For example, with composite honeycomb sandwich structure, a vapor barrier appliqu{acute over (e)} coating can slow or eliminate the migration of water through the laminated face sheets into the honeycomb core.
Preferred appliqu{acute over (e)}s provide corrosion resistance to the underlying surface because they incorporate an intermediate vapor barrier. Preferred appliqu{acute over (e)}s have a 1-8 mil fluoroe
Dull Dennis L.
Rawlings Diane C.
Beck Shrive
Crockford Kirsten A.
Hammar John C.
The Boeing Company
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