Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Cellular products or processes of preparing a cellular...
Reexamination Certificate
2001-01-08
2003-07-01
Foelak, Morton (Department: 1711)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Cellular products or processes of preparing a cellular...
C521S092000, C521S154000
Reexamination Certificate
active
06586483
ABSTRACT:
BACKGROUND OF THE INVENTION
The invention relates to foaming compositions that include surface-modified nanoparticles.
Pure liquids generally cannot foam unless a surfactant is present in the liquid. The surfactant functions by lowering the surface tension of the liquid such that a gas bubble introduced below the surface of the liquid can be maintained in the liquid. The surfactants can also stabilize the foam after it is formed. Such surfactants include, e.g., ionic, nonionic and polymeric surfactants.
In some applications, surfactant may migrate to the surface of the composition, which may lead to undesirable consequences. In pressure sensitive adhesive compositions, for example, surfactants may affect the adhesive properties of the composition, and in medical applications the presence of surfactants at the surface of an article, e.g., a bandage, may lead to deleterious hygiene effects.
Inorganic particles are included in many foam compositions for a variety of reasons. Some of these particles function as nucleating agents. Other particles act as filler to alter the physical properties of the composition including, e.g., altering the rheology of the composition. Still other particles, hydrophobic fumed silica for example, have been found to function as defoaming agents. Fumed silica, which is also known as pyrogenic silica, consists of primary particles that are irreversibly bonded together in the form of aggregates, which have an average size of from 200 nm to 300 nm.
SUMMARY
In one aspect, the invention features a foam composition that includes a vehicle and surface-modified nanoparticles disposed in the vehicle, the individual nanoparticles having a particle diameter of less than about 100 nanometers. In one embodiment, the foam is essentially free of surfactant. In another embodiment, the foam composition further includes surfactant. In various embodiments, the foam composition includes at least about 0.5% by weight, at least about 1% by weight, at least about 2% by weight, at least about 5% by weight or at least about 10% by weight surface-modified nanoparticles.
In various embodiments, the individual nanoparticles have a particle diameter no greater than about 50 nanometers, from about 3 nanometers to about 50 nanometers, no greater than about 20 nanometers, from about 3 nanometers to about 20 nanometers and from about 3 nanometers to about 10 nanometers.
In one embodiment, the nanoparticles are selected from the group consisting of silica, titania, alumina, zirconia, vanadia, ceria, iron oxide, antimony oxide, tin oxide, aluminum/silica and combinations thereof.
In some embodiments, the nanoparticles include surface groups selected from the group consisting of hydrophobic groups, hydrophilic groups and combinations thereof. In other embodiments, the nanoparticles include surface groups derived from an agent selected from the group consisting of a silane, organic acid, organic base and combinations thereof. In other embodiments, the nanoparticles include organosilyl surface groups derived from an agent selected from the group consisting of alkylsilane, arylsilane, alkoxysilane, and combinations thereof.
In one embodiment, the nanoparticles include surface groups derived from an agent selected from the group consisting of carboxylic acid, sulfonic acid, phosphonic acid, and combinations thereof.
In some embodiments, the vehicle includes monomer, oligomer, polymer or a combination thereof. In other embodiments, the vehicle includes polymer selected from the group consisting of thermoplastic polymers, thermoset polymers, elastomers and mixtures thereof. In another embodiment, the vehicle includes a polymer selected from the group consisting of natural rubber, synthetic rubber, acrylonitrile-butadiene rubber, polyisoprene rubber, polychloroprene rubber, polybutadiene rubber, butyl rubber, ethylene-propylene-diene monomer rubber, ethylene-propylene rubber, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-butadiene-styrene rubber, styrene-isoprene-styrene rubber, styrene-ethylene-butylene-styrene rubber, styrene-ethylene-propylene-styrene rubber, polyisobutylene rubber, ethylene vinyl acetate rubber, silicone rubber, polyvinyl ethers and combinations thereof. In one embodiment, the vehicle includes a polymer selected from the group consisting of polyester, polyurethane, amino resin, alkyd resin, phenolic resin, epoxy resin, isocyanate resin, isocyanurate resin polysiloxane resin and mixtures thereof. In other embodiments, the vehicle includes a polymer selected from the group consisting of polyacrylonitrile, acrylonitrile-butadiene-styrene, styrene-acrylonitrile, cellulosic polymers, chlorinated polyether, ethylene vinyl acetate copolymers, polyamides, polyimides, polycarbonates, polyolefins, polyethylene terephthalate, polyphenylene oxides, polystyrene, polyurethanes, polyisocyanurates, polyvinyl chloride, polyvinyl acetate, polyvinyl alcohols, polyvinyl butyral, polyvinyl pyrrolidone, polyvinylidene chloride and mixtures thereof.
In one embodiment, the vehicle includes acrylic resin. In some embodiments, the acrylic resin includes acrylic or methacrylic acid ester of a monohydric alcohol having from 1 to 20 carbon atoms.
In some embodiments, the vehicle is nonpolymerizable. In other embodiments, the vehicle is essentially free of polymers. In one embodiment, the vehicle includes polyolefin. In some embodiments, the vehicle includes a metallocene polymerized polyolefin.
In other embodiments, the vehicle includes resin selected from the group consisting of novolac, resole and polyurea resins and mixtures thereof.
In one embodiment, the vehicle is selected from the group consisting of water, alcohols, aldehydes, ketones, esters, ethers, amines, amides, hydrocarbons, halocarbons and mixtures thereof.
In another embodiment, the foam composition further includes a foaming agent.
In one embodiment, the surface-modified nanoparticles include statistically averaged randomly surface-modified nanoparticles.
In one embodiment, the surface-modified nanoparticles include surface groups having a solubility parameter similar to the solubility parameter of the vehicle.
In one embodiment, the surface-modified nanoparticles appear to be dissolved in the vehicle.
In another embodiment, the vehicle includes an adhesive composition. In other embodiments, the vehicle includes a pressure sensitive adhesive composition. In one embodiment, the pressure sensitive adhesive composition includes acrylic resin. In some embodiments, the acrylic resin includes an acrylic or methacrylic acid ester of a monohydric alcohol having from 1 to 20 carbon atoms. In one embodiment, the pressure sensitive adhesive composition includes isooctyl acrylate and acrylic acid copolymer.
In another embodiment, the vehicle includes a hot melt adhesive composition.
In another aspect, the invention features an adhesive tape (e.g., a pressure sensitive adhesive tape) including an above-described foam composition. In other embodiments, the adhesive tape further includes a substrate and the foam composition is disposed on the substrate. In some embodiments, the foam composition includes an acrylic resin. In one embodiment, the acrylic resin includes acrylic or methacrylic acid ester of a monohydric alcohol having from 1 to 20 carbon atoms.
In another aspect, the invention features an article that includes an above-described foam composition. In one embodiment, the article is a gasket. In other embodiments, the article is automobile body molding.
In other aspects, the invention features a method of making a foam that includes introducing a foaming agent into a composition in an amount sufficient to form voids in the composition, where the composition includes a vehicle and surface-modified nanoparticles disposed in the vehicle and the surface-modified nanoparticles have a particle diameter of no greater than about 100 nanometers. In some embodiments, the step of introducing a foaming agent includes mechanically stirring the composition. In some embodiments, the step of introducing a foaming agent includes a chemic
Baran, Jr. Jimmie R.
Johnson Gordon G.
Johnson Michael A.
Kolb Brant U.
Lehmann Megan P.
3M Innovative Properties Company
Bardell Scott A.
Foelak Morton
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