Coating processes – Applying superposed diverse coating or coating a coated base – Synthetic resin coating
Reexamination Certificate
2000-05-02
2003-07-08
Chen, Bret (Department: 1762)
Coating processes
Applying superposed diverse coating or coating a coated base
Synthetic resin coating
C427S294000, C427S379000, C427S408000, C427S409000
Reexamination Certificate
active
06589603
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to pre-formed substrates coated with multi-layer composite coatings and a process for applying multi-layer coating compositions to such substrates. More particularly the invention relates to a pre-formed substrate having different coatings on respective lateral faces of the substrate and also to a process for forming and drying an exterior-durable multilayer composite coating on three-dimensional, multi-faced substrates.
BACKGROUND OF THE INVENTION
For many years, pre-formed lineal substrates have been used to construct windows, doors and other architectural components. Frequently, it is desirable to provide such lineal substrates with two or more colors on respective lateral faces. Although these multi-colored substrates having been available for use in the industry for some coating systems, such multi-colored substrates are cost-prohibitive for several reasons.
For example, in applications where a multi-colored substrate is required to have a first coating over the second coating, a time-consuming and often expensive process is required for applying and drying the first coating and subsequently masking the substrate prior to application of the second coating.
Further, although aqueous-based coating compositions afford environmental and other advantages, in cases where the second color coating is deposited from an aqueous-based coating composition over an organic solvent-borne base coating, it is sometimes difficult to obtain a continuous and coalesced topcoat film. That typically is because the solid surface tension of the base coating is greater than the liquid surface tension of the top coating which can result in the inability of the top coating composition to “wet out” or flow smoothly over the base coating.
Moreover, if the underlying coating is a thermoplastic composition, it is often difficult to use conventional masking techniques when the second coating is dried or cured under thermal conditions. At the drying temperature of the second layer, the thermoplastic first layer can interact with the masking material. This interaction can result in damage or destruction to the thermoplastic first layer as the masking material is removed.
Accordingly, there was a need in the prior art for improvements that would allow the wider use of aqueous-based coating compositions. Also, there was need in the art for improvements that would allow the use of thermal-drying techniques for coating compositions applied over underlying thermoplastic coatings.
In addition, durable coatings suitable for application to pre-formed, three-dimensional, multi-faced substrates, for example, architectural and building components such as extruded aluminum parts for window and door frames, are well known in the art. Such durable coatings must provide attractive finishes which will cover the substrate and any previously applied coating, for example, a primer coating, while providing resistance to fading, loss of gloss or color change due to outdoor exposure.
Coatings based on fluoropolymers, for example, poly(vinylidene fluoride) and vinylidene fluoride copolymers, are known for their outstanding exterior durability properties, providing tough finishes resistant to crazing, chalking and color change upon weathering.
U.S. Pat. No. 3,470,014 discloses an exterior durable multilayer coating formed from a primer layer having a film thickness of 0.1 to 4.0 mils (2.5 to 100 micrometers), and a second clear layer comprising a fluorocarbon copolymer having a film thickness of 0.1 to 2.0 mils (2.5 to 50 micrometers). The primer layer comprises a pigmented aqueous composition including an aqueous acrylic copolymer dispersion (or latex) prepared from a polymerizable acrylic acid ester and a primary alkanol, a polymerizable alkyl methacrylate, and an alpha, beta-unsaturated carboxylic acid. The second clear layer comprises a solvent-based composition including a copolymer of vinylidene fluoride and tetrafluoroethylene or perfluoropropene. The coatings are useful for application to wooden or aluminum substrates, such as those used as building materials. The primer coating and the clear coating compositions typically are applied by curtain or roll-coating and each are dried by exposing the coated substrates to thermal conditions.
U.S. Pat. No. 4,314,004 discloses a method for providing durable coated substrates comprising the steps of (a) applying a pigmented coating composition to a substrate wherein the composition consists essentially of 45 to 85 percent based on resin solids of a fluorocarbon resin and a pigment at a pigment volume concentration of from 3 to 55 percent; (b) applying a clear coating composition to the coated substrate of step (a) wherein the clear composition consists essentially of 45 to 85 percent of a fluorocarbon resin and from 15 to 55 percent of an acrylic resin based on resin solids; and (c) baking the coated substrate of step (b) thereby causing the coatings to fuse together in a bonding process. Useful fluorocarbon resins include polyvinyl fluorides, polyvinylidene fluorides, vinyl fluoride copolymers and vinylidene fluoride copolymers. The acrylic resins used in conjunction with the fluorocarbon resins can be thermosetting or thermoplastic resins. The methods are useful for coating primed metal surfaces, for example, aluminum building panels where the multi-layer fluorocarbon resin-containing coatings provide excellent intercoat adhesion believed to result from the presence of fluorocarbon resin in both coatings (see column 4, lines 41-43).
U.S. Pat. No. 4,720,405 discloses a coating composition comprising an organic polyol, a polyepoxide, a polyisocyanate crosslinking agent and a phenolic resin suitable for use as a flexible primer coating for application to structural building components, such as metal building panels. Also disclosed is a method for providing a substrate with a multi-layer coating comprising the following steps: (a) applying the above-described primer coating; (b) applying a pigmented coating composition comprising a fluoropolymer to the coated substrate of step (a); (c) applying a clear coating composition comprising a fluoropolymer to the coated substrate of step (b); and at least partially curing the coated substrate of step (c). The cured multi-layer coating has an elongation of at least 10 percent. The multi-layer coating has excellent durability and resistance to weather and aggressive environments.
U.S. Pat. No. 4,659,768 discloses a thermosetting solvent based coating composition comprising about 45 percent of a fluorocarbon polymer in conjunction with at least about 10 percent of a hydroxy-functional organic soluble copolymer based on 2-hydroxyethyl acrylate, and an aminoplast curing agent. Such coatings exhibit improved water spot resistance and minimum color change and gloss loss upon exterior exposure. The coatings are suitable for application to prime-coated aluminum substrates.
U.S. Pat. No. 4,824,728 discloses a durably coated substrate coated with a multi-layer coating. The multi-layer coating includes heavily pigmented opaque base coat composition containing a fluorocarbon resin in conjunction with an acrylic resin and a top coat over the base coat derived from a top coat composition containing a fluorocarbon resin in conjunction with an acrylic resin. The top coat has a pigment content insufficient to prevent the color of the base coat from being easily seen. The substrates include aluminum as well as hot-dipped galvanized steel substrates. The coatings can be applied by spray application techniques to coiled metal stock which is subsequently fabricated, or pre-formed substrates.
Window and door frames typically are constructed from pre-formed, three-dimensional, multi-faced substrates including elastomeric substrates, such as vinyl substrates, wooden substrates and metallic substrates, such as extruded aluminum substrates. Typically, since at least one side of the installed window or door frame is exposed to the outdoor environment, the coating applied thereto must possess a high degree of exterior dura
Conley Carole A.
Cornell Howell N.
Millero Edward R.
Perrett Evelyn D.
Sturdevant Shelley D.
Altman Deborah M.
Chen Bret
Fletcher, III William Phillip
Meyers Diane R.
PPG Industries Ohio Inc.
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