Stock material or miscellaneous articles – Composite
Reexamination Certificate
1995-06-07
2004-06-08
Rickman, Holly (Department: 1773)
Stock material or miscellaneous articles
Composite
C428S447000, C428S451000, C428S483000, C428S515000, C428S519000, C428S521000, C428S413000, C428S500000, C427S108000, C427S164000, C427S407100, C427S064000
Reexamination Certificate
active
06746770
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to material composites, such as layered structures and admixtures, of electrically conductive polymers and abrasion/scratch resistant materials, uses thereof and structures fabricated therewith. More particularly, this invention relates to composites of electrically conductive substituted and unsubstituted polyanilines, substituted and unsubstituted polyparaphenylenevinylenes, substituted and unsubstituted polythiophenes, substituted and unsubstituted polyazines, substituted and unsubstituted polyfuranes, substituted and unsubstituted polpyrroles, substituted and unsubstituted polyselenophene, substituted and unsubstituted poly-p-phenylene sulfides and polyacetylenes formed from soluble precursors in a combination with silicones siloxanes, acrylates, methacrylates, epoxies, epoxyacrylates and styrenes.
BACKGROUND OF THE INVENTION
Electrically conducting organic polymers have been of scientific and technological interest since the late 1970's. These relatively new materials exhibit the electronic and magnetic properties characteristic of metals while retaining the physical and mechanical properties associated with conventional organic polymers. Technological application of these polymers are beginning to emerge. Herein we describe admixtures and composites of abrasion/scratch resistant materials and electrically conducting polymers, such as, polyparaphenylenevinylenes, polyanilines, polythiophenes, polyfuranes, polypyrroles, polyselenophenes, poly-p-phenylene sulfides, polyacetylenes formed from soluble precursors.
Quite surprisingly, it has been found that these composite materials retain abrasion/scratch resistance and electrical conductivity in the admixture since there is a chemical compatibility between the abrasion/scratch resistant material and the electrically conducting polymer which makes them compatible thereby permitting one to intermix with the other without either forming a precipitate. Abrasion and scratch resistant materials will be referred to herein as hard coats. Because of the electrostatic properties of these materials they can be used as an electrostatic charge (anti static) or electrostatic discharge layer. Moreover, since the materials of the present invention retain the hardness of the abrasion resistant component they can be used as scratch resistant electrostatic coatings. Moreover, since in the preferred embodiments, the composite materials are transparent, they are useful as electrostatic antistatic coatings (anti-stats) on visual displays such as CRT screens, in particular, to substantially prevent electrostatic dust accumulation thereon. The composite materials are also useful as anti-stats for semiconductor wafer or electronic device substrate carriers, for electrostatic discharge (ESD) applications as charge dissipators in clean rooms wherein semiconductor device fabrication occurs and possibly as electromagnetic interference (EMI) shields.
Currently used anti-stat and ESD materials are typically thin metallic films, such as indiumtin oxide which are expensive to fabricate and are not abrasion resistant. Also, ionic salts have been used. However, these systems are very unstable in terms of their conductivity as the conductivity is very much dependent on humidity. The composite materials of the present invention are inexpensive, abrasion/scratch resistant, environmentally stable and the preferred embodiments are light transmitting.
The conducting composites, according to the present invention, have substantially enhanced solvent, water and alkaline solution stability as compared to where a conducting polymer is used alone. Many of the conducting polymers lose their electrically conductive property when exposed to water since the dopant which renders the polymer electrically conductive is removed by the water. Therefore, over time water will remove the dopant and render the conductive polymer non conductive. In addition, many solvents, e.g. organic, will dissolve the conducting polymer and therefore remove it from the substrate. Quite surprisingly, it has been found that when the admixture of the conductive polymer and a hard coat or a layer of conductive polymer covered with a hard coat is exposed to water the conductive polymer does not lose its conductivity. In addition, the composites arc not readily removed by solvents.
It is an object of this invention to provide a composite polymeric material which is scratch and abrasion resistant and electrically conductive.
It is another object of the present invention to provide a composite polymeric material which is scratch abrasion resistant, electrically conductive and light transmitting also having good adhesion, water stability and solvent stability, and alkaline solution stability.
It is another object of the present invention to use the transparent composite polymeric compositions of the present invention as electrostatic charge (ESC) (anti static) and electrostatic discharge (ESD) layers, in particular, on visual displays.
It is another object of the present invention to provide methods of fabricating the composite polymeric materials according to the present invention.
SUMMARY OF THE INVENTION
A broad aspect of this invention is a polymeric composite material which is either an admixture of a hard coat material and an electrically conductive polymeric material or a 2 layer system consisting of a layer of electrically conductive polymer disposed on a surface followed by a thin layer of the hard coat on top.
In a more particular aspect of the present invention, the polymeric material has a partially conjugated &pgr; system which is extended by the addition of dopants to the polymeric material to provide at least enough &pgr; conjugation so that the &pgr; conjugated parts of a molecule of the polymer are substantially in contact with the &pgr; conjugated parts of an adjacent molecule.
In another more particular aspect of the present invention, the conductive polymer is selected from substituted and unsubstituted polyparaphenylenevinylenes, substituted and unsubstituted polyanilines, substituted and unsubstituted polythiophenes, substituted and unsubstituted polyazines, substituted and unsubstituted poly-p-phenylene sulfides, substituted and unsubstituted polypyrroles, substituted and unsubstituted polyselenophene, polyacetylenes formed from soluble precursors, combinations thereof and blends thereof with other polymers.
In another aspect of the present invention, a solution or dispersion of a scratch/abrasion resistant material is mixed with a solution or dispersion of an electrically conducting polymeric material from which the solvent is removed, leaving a compatible mixture of the electrically conducting and scratch resistant materials.
In another more particular aspect of the present invention, the combination of the conductor and hard coat is light transmitting.
In another more particular aspect of a method according to the present invention, a solution or dispersion is formed from a soluble electrically conductive polymer having an extended &pgr; conjugated system with an abrasion/scratch resistant material and a solvent. The solution is mixed and deposited onto the surface of a substrate, dried to remove the solvent leaving a solid solution of the conductive polymer and abrasion/scratch resistant material. The conductive polymer is substantially uniformly intermixed with the abrasion/resistant material substantially without precipitates of either the conducting or abrasion resistant components.
In a more particular aspect of the present invention, the composite materials are transparent.
In another more particular aspect of the present invention the scratch/abrasion resistant materials are silicones/siloxanes and other cross linkable materials including acrylates, methacrylates, styrenes and epoxies and epoxy acrylates.
Another more particular aspect of the present invention is a composite structure of an electrically conductive layer, preferably an electrically conductive polymer, on a substrate surface with a hard coat layer disposed on
Afzali-Ardakani Ali
Angelopoulos Marie
Dickerson Jack Alvin
Gelorme Jeffrey Donald
Pillsbury Thomas Baird
Internatonal Business Machines Corporation
Morris Daniel P
Rickman Holly
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