Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
2002-08-02
2004-09-14
Buttner, David J. (Department: 1712)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S421000, C428S422000, C428S423100, C428S413000, C428S3550EP, C428S418000, C428S457000, C428S480000, C428S500000, C428S523000
Reexamination Certificate
active
06790526
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to halopolymer materials with adhesive surfaces, and more specifically, to protective appliqués as paint replacements for a wide range of substrates. The appliqués are layered structures, or polymeric films, generally halopolymers which have been modified by the introduction of surface hydrogen and oxygen or oxygen-containing functionalities. These reactive sites are suitable for chemically bonding with adhesive materials to form composite structures possessing superior peel strengths, resistance to delamination and protective properties when applied to surfaces, as replacements for the usual protective paint systems widely used in the aerospace, land and marine fields in general, and including the chemical, food processing and transportation industries. More particularly, the appliqués find numerous applications for aircraft and spacecraft parts and assemblies, partial and complete fuselage panels, wings for enhancing laminar flow, reducing ice formation and friction, entire aircraft hulls, aircraft markings and decals; replacements for paints, including architectural or as decorative appliqués suitable for printing, with emblems for use as transfer films and decals for rail cars, highway vehicles, including tractor-trailer rigs; protective films for marine vessels, and so on. The adhesive backed appliqués also have numerous utilities for internal surfaces, such as protective liners for containment vessels in the chemical and food processing industries, to name but a few.
BACKGROUND OF THE INVENTION
Halopolymers are a group of polymers with carbon chains wherein all or a percentage of the carbons have covalently bonded halogen atoms. Halopolymers are characterized by extreme inertness, high thermal stability, hydrophobicity, low dielectric properties and low coefficients of friction. Representative examples of halopolymers that exhibit these characteristics include fluoropolymers and fluorochloropolymers, such as fluorohydrocarbon polymers, e.g., polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polychlorotrifluoroethylene (PCTFE), including the well known fluorocarbon polymers, e.g., perfluorinated polymers, like polytetrafluoroethylene (PTFE), expanded polytetrafluoroethylene (ePTFE), FEP, perfluoroalkoxy polymer like PFA and MFA and copolymers and terpolymers thereof, for example, a terpolymer derived from TFE, hexafluoropropylene and vinylidene fluoride (THV), etc. However, because halopolymers are so inert and have low coefficients of friction, they will not reliably bond to other surfaces, or bond to value-added molecules. As such, the sought after characteristics of a halopolymer, such as inertness and hydrophobicity are not easily transferred to another substrate because of the difficulty in adhering a halopolymer film to the substrate.
Several attempts have been made to modify halopolymers to provide more bondable surfaces. For instance, U.S. Pat. No. 4,933,060 discloses a reactive gas plasma process wherein a glow discharge in an oxygen containing atmosphere leads to the formation of oxygen-containing functionalities on the surface. However, this method merely etches the surface creating transient oxygen-containing functionality, and the activity of the bonding sites is short-lived rendering an etched material with a limited shelf-life. Furthermore, the polymeric chains containing the oxidized surface functionalities undergo unavoidable reorientation due to their low molecular weights and subsequent migration, as described by H. Yasuda et. al. in
J. Polym. Sci.: Polym. Phys. Ed
., 19, 1285 (1981). As a result, surfaces of an etched halopolymer have limited periods of reactivity, and must be applied to an adhesive before reorientation of the etched surface. Moreover, bonds formed between the adhesive and etched halopolymer material lack permanency and tend to degrade under UV radiation, humidity and thermal stress conditions, due to rearrangement of the polymer. British Pat. Pub. 998,807 provides for a method of increasing adhesiveness of halopolymers using corona discharge plasma in an inert atmosphere which is essentially oxygen-free. However, the processed material must be maintained in an oxygen-free atmosphere to retain activity. Once the surface is exposed to moisture or oxygen the treated surface becomes deactivated limiting useful shelf-life. Furthermore, corona discharge plasmas are non-uniform plasmas generated from a point source, so the processed material is not uniformly modified or activated. The lack of uniformity of the surface disrupts continuity in batch production of the modified film.
A further method of modifying halopolymer materials to increase adhesiveness includes etching the halopolymer material by reacting with an alkali metal and naphthalene. However, this method provides a low level of defluorination. Consequently, the material readily degrades under thermal and ultraviolet stress conditions. Furthermore, the surface is chemically roughened (i.e., etched) which, in addition to an inconsistent degree of modification, provides nothing more than a non-permanent mechanical bond.
Fluoropolymers have also been suggested for use in the fabrication of paint replacement films, especially as corrosion protective surface coatings, for instance, in the form of appliqués. They have been of interest in both commercial avaition and for aerospace applications. Durable paint replacement films offer potential benefits of lower aircraft production costs, reduced maintenance requirements, weight reduction, environmental benefits, to name but a few.
One example of exterior protective appliqués intended as replacements for aviation paint systems for reduced lifecycle costs, improved performance and protection of surfaces from corrosion is disclosed by U.S. Pat. No. 6,177,189, to Rawlings et al. A paintless coating system is disclosed for replacing conventional paints on metal or composite aerospace parts and assemblies consisting of an appliqué having a topcoat or external film, a vapor barrier interfacing with and completely underlying the topcoat, and an adhesive on at least one face of the vapor barrier for adhering the appliqué to a surface of the part or assembly. More specifically, the topcoat consists of an organic resin matrix elastomeric composite, particularly a rain and thermal resistant fluoroelastomer. The intermediate vapor barrier which functions to eliminate active transport of water vapor or other corrosive agents to the substrate being coated, consists of a terpolymer derived from TFE, hexafluoropropylene and vinylidene fluoride. The preferred adhesive is a pressure sensitive acrylic. According to Rawlings et al the adhesive should hold the appliqués on the surface during normal operation, but should also be peelable without leaving a residue on the substrate for easier replacement.
While Rawlings et al reported that testing of their appliqués provided protection at 500 mph, comparable to special rain coatings in some conditions, they also observed delamination occurring in several test specimens between the topcoat film layer and the vapor barrier.
Accordingly, it would be highly desirable to have improved adherent protective halopolymeric surface coatings or appliqués as a paintless system of protective films for a wide range of end use applications for both interior and exterior surfaces, especially including aerospace, land and marine applications which not only provide the needed protective barrier against corrosion, but are also more fail safe in resisting delamination between the layers of the composite under the most severe operating conditions.
SUMMARY OF THE INVENTION
It is therefore an object of the present invention to provide surface modified halopolymers which repel water and other polar solvents, as well as non-polar solvents, possess high thermal stability, low friction coefficients and chemically bond to adhesive substances to form permanent bonds with superior strength.
It is a further object of this invention to provide adhesive-oxyhalopolymer composites comp
Brupbacher John M.
Dalgleish Andrew W.
Holdsworth Garner S.
Koloski Timothy S.
Vargo Terrence G.
Buttner David J.
Ellis Howard M.
Integument Technologies, Inc.
Keehan Christopher
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