Compositions – Electrically conductive or emissive compositions
Reexamination Certificate
1999-05-27
2001-10-09
Kopec, Mark (Department: 1751)
Compositions
Electrically conductive or emissive compositions
C501S133000, C428S922000
Reexamination Certificate
active
06299799
ABSTRACT:
TECHNICAL FIELD
The present invention relates to ceramer compositions comprising an electrically conductive organic polymer, abrasion resistant, antistatic ceramer articles prepared from these ceramer compositions, and to methods of making these ceramers and ceramer compositions.
BACKGROUND
The incorporation of additives into polymers are known in the art. There has been extensive use of additives, such as antifog agents, antioxidants, plasticisers, stabilizers, infra-red absorbers, biocides, flame retardants, fillers, lubricants, non-ionic surfactants, etc., in polymer technology. Such additives may be in the form of, for example, liquids, pastes, waxy low-melting solutions, or solids.
Plastics are electrically insulative and may generate and accumulate static electricity by contact or friction with material or by being peeled from a material during production or use thereof. Plastics having high electrical conductivity are able to avoid the accumulation of electricity and therefore are antistatic. Optically transparent electrically conductive coatings are known in the art for use in display devices, photoconductive components, and solar photovolaic cells. U.S. Pat. No. 5,770,216 discusses films containing zinc oxide particles as additives. U.S. Pat. No. 5,300,575 discusses plastic films containing polythiophene compounds having high electrical conductivity.
Some antistatic coatings fail to conduct electricity under relatively low humidity. For example, antistatic coatings comprising ionic conductors dispersed in organic matrices typically require water to conduct electricity. Charge is transported in the presence of water and conduction of electricity may stop when the antistatic coating is placed under approximately 20% relative humidity. Unlike ionic conductors, an electrically conducting organic material, such as polythiophene, dispersed in an organic matrix is capable of conducting electricity below about 20% humidity. Conduction of electricity may occur when the organic matrix containing the electrically conductive organic polymer is placed in a relatively dry environment because electrons move through conjugated double bonds located within the polymer backbone. However, an organic matrix comprising an electrically conductive organic polymer may be easily scratched limiting the use of the polymer under certain circumstances.
SUMMARY
The present invention provides ceramer compositions capable of being cured to form abrasion resistant, antistatic ceramers. Ceramer compositions of the present invention comprise a plurality of colloidal silica particles, a binder precursor, and a dispersion of an electrically conductive organic polymer. In a preferred embodiment, the ceramer composition further comprises an amide-containing compound. Such amide-containing compounds increase the transparency of the cured ceramer. The ceramer composition may further comprise colloidal inorganic oxide particles, coupling agents, coating modifying agents (e.g., initiators and photosensitizers), surfactants, and other optional additives.
The present invention also embodies ceramer articles made from the ceramer compositions. Such ceramer articles may comprise a substrate having a ceramer coating adhered to at least a portion of the surface of the substrate. Suitable substrates include, for example, polymer film, glass, ceramic, metal, and the like. A particularly suitable substrate is an electronic storage container. Ceramer articles may also comprise, for example, shaped ceramer particles.
The present invention also embodies a method of making a ceramer composition for producing a transparent ceramer having antistatic properties and abrasion resistance. The method comprises the steps of: a) combining an aqueous silica sol with optional coupling agents and a binder precursor to form a mixture; b) drying the mixture of step a) so that the mixture is substantially free of water; c) mixing an amide-containing compound with an electrically conductive organic polymer to form a dispersion of electrically conductive organic polymers; and d) combining the dispersion of electrically conductive organic polymer of step c) with the mixture of step b) to form the ceramer composition. An antistatic, abrasion resistant ceramer is produced when the material of step d) is cured.
The present invention also includes a method of making a ceramer composition, the method including the steps of: a) combining an aqueous silica sol with optional coupling agents and at least one organic monomer to form a mixture; b) drying the mixture of step a) so that the mixture is substantially free of water; and c) combining an electrically conductive organic polymer with the mixture of step b) to form a ceramer composition. An antistatic, abrasion resistant ceramer is produced when the material of step c) is cured.
As used herein with respect to the present invention, the following shall apply:
“Binder” refers to solidified or hardened binder precursor.
“Binder precursor” refers to a curable composition comprising at least one reactive monomer, oligomer, or a combination thereof.
“Ceramer” refers to a cured ceramer composition.
“Ceramer composition” refers to a flowable dispersion comprising substantially non-aggregated, colloidal inorganic oxide particles (including at least silica particles) uniformly incorporated in at least one binder precursor.
“Coating” refers to a layer of ceramer.
“Coupling agent” refers to organic molecules wherein the molecules have a first functional group capable of covalent or ionic bonding to a silicate particle, an optional second functional group capable of reacting with an organic precursor, and a hydrophobic segment attached to the first functional group and located between the first and second functional groups if the second functional groups are present. A coupling agent may function as a dispersant.
“Curable” refers to a flowable material that can be transformed into a solid, substantially non-flowing material by means of cooling (to solidify hot melts), heating (to dry and solidify materials borne by solvent), and/or polymerization (e.g., chain extension, chemical crosslinking, radiation crosslinking, or the like).
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Bilkadi Zayn
Craig Bradley D.
3M Innovative Properties Company
Kopec Mark
Pribnow Scott R.
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