Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Adhesive outermost layer
Reexamination Certificate
1999-01-27
2002-08-06
Ogden, Necholus (Department: 1751)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Adhesive outermost layer
C428S411100, C428S421000, C428S416000, C156S302000
Reexamination Certificate
active
06428887
ABSTRACT:
TECHNICAL FIELD
The present invention relates generally to halopolymer materials with adhesive surfaces, and more specifically, to adhesive-oxyhalopolymer composites having surface hydrogen and oxygen or oxygen functionality groups wherein the oxygen or oxygen functionality sites are chemically bonded to an adhesive material forming a permanent bond.
BACKGROUND OF THE INVENTION
Halopolymers are a group of polymers that consist of carbon chains wherein all or a percentage of the carbons have covalent bonds to halogens 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), and expanded polytetrafluoroethylene (ePTFE). 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 thereby 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 weight and subsequent migration, as described by H. Yasuda et. al. in
J. Polym. Sci.: Polym. Phys. Ed.,
19, 1285 (1981). As a result, the surface of an etched halopolymer has limited time of reactivity, and therefore, must be applied to an adhesive before reorientation of the etched surface. Moreover, a bond formed between the adhesive and etched halopolymer material is not permanent and tends to degrade under UV radiation, humidity and thermal stress conditions due to rearrangement of the polymer.
British Patent Specification No. 998,807 provides for a method of increasing adhesiveness of a halopolymer 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 maintain activity. Once the surface is exposed to moisture or oxygen the treated surface is deactivated thereby 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. Thus understood, the non-uniformity of the surface prevents any continuity in batch production of the modified film.
Another method of modifying a halopolymer material to increase adhesiveness includes etching the halopolymer material by reacting the material with alkali metal and naphthalene. However, this method provides a low level of defluorination and the material degrades easily 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.
Accordingly, it would be highly desirable to have a halopolymer material possessing all the desired properties of inertness, stability, hydrophobicity, but which can chemically bond to an adhesive to form a permanent and stable bond.
SUMMARY OF THE INVENTION
It is a principal object of the present invention to provide a surface modified halopolymer which repels water and other polar solvents, has high thermal stability, has a low friction coefficient and chemically bonds to an adhesive substance forming a permanent bond having surprisingly and unexpected superior bond strength.
It is another object of this invention to provide an adhesive-oxyhalopolymer composite comprising a modified halopolymer material having substituted functional groups that chemically bond to an adhesive material forming a bond that does not degrade due to chemical attack, ultraviolet radiation, humidity, temperature extremes, salt, acid or caustic agents, steam and/or reorientation of substituted functional bonding sites.
Yet another object is to provide an adhesive-oxyhalopolymer composite that can withstand attack by chemicals, ultraviolet radiation, humidity, temperature extremes, salt, acid or caustic agents and steam.
A further object of the present invention is to provide a surface modified halopolymer film having two sides of which the first side is chemically bonded to an adhesive whereby during the wrapping or overlapping of the film the adhesive coated first side will bond to the second side.
A still further object is to provide an adhesive-oxyhalopolymer composite wherein the oxyhalopolymer is uniformly treated and reproducible thereby providing quality control in the adhesive end product.
Yet another object is to provide methods for preparing an adhesive-oxyhalopolymer composite having a modified surface which is not roughened or damaged by plasma etching, but instead controllably modified by the incorporation of hydrogen and oxygen functionality groups onto the surface matrix of the oxyhalopolymer thereby imparting permanent chemical reactivity to the surface.
In this regard, it has been discovered that when the surface of a halopolymer material is exposed to radio frequency glow discharge (RFGD) in the presence of a hydrogen gas-vapor mixture comprising water, methanol, or other oxygen containing liquids (i.e., formaldehyde), a modified surface forms which comprises a controllably reduced amount of the original halogens which are replaced with controlled amounts of hydrogen and oxygen or oxygen-containing groups covalently bonded to the carbon backbone of the polymer. The surface modified halopolymer material, which is an oxyhalopolymer, retains the unique properties of the original halogenated material. In addition, the surface modified halopolymer or oxyhalopolymer is quite reactive and chemically bonds with an adhesive substance forming a stable and permanent bond with surprisingly and unexpected superior bond strength.
The oxyhalopolymer material may be in the form of a film, sheet, powder, bead, fiber, mesh, mold, coating, tubing, porous veiled material or any other shape utilized for a specific application. When the oxyhalopolymer material is chemically bonded to an adhesive the resulting adhesive-oxyhalopolymer composite of the present invention may be applied to almost any surface including metal, non-metal, wood, ceramic, glass and plastic thereby imparting the desirable properties of a halopolymeric material to the new surface. These adhesive-oxyhalopolymer composites are useful for innumerable household and industrial applications an can be applied to a substrate in situ, to preserve, protect and extend the life of the object. Such objects may include the bases of telephone poles, fence posts, concrete foundations, drain gutters, airplane wings to reduce ice formation, hulls of ships and docks to prevent marine biofouling, fume hoods, machine tools, walls of buildings as anti-graffiti coatings, bondable gaskets, chemical containment vessels and pipes for protecting the containment structure, coil coatings, metals, such as carbon steel or any other surfaces which may be damaged or corroded by exposure to humidity, mildew, temperature, salt, corrosive chemicals, weather or ultraviolet (UV) radiation
Koloski Timothy S.
Naab Douglas J.
Vargo Terrence G.
Ellis Howard M.
Integument Technologies, Inc.
Ogden Necholus
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