Classifications

• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N59/00—Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
  • A01N59/16—Heavy metals; Compounds thereof
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
  • A01N25/08—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests containing solids as carriers or diluents
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N25/00—Biocides, pest repellants or attractants, or plant growth regulators, characterised by their forms, or by their non-active ingredients or by their methods of application, e.g. seed treatment or sequential application; Substances for reducing the noxious effect of the active ingredients to organisms other than pests
  • A01N25/34—Shaped forms, e.g. sheets, not provided for in any other sub-group of this main group
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N59/00—Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
  • A01N59/02—Sulfur; Selenium; Tellurium; Compounds thereof
• • A—HUMAN NECESSITIES
  • A01—AGRICULTURE; FORESTRY; ANIMAL HUSBANDRY; HUNTING; TRAPPING; FISHING
  • A01N—PRESERVATION OF BODIES OF HUMANS OR ANIMALS OR PLANTS OR PARTS THEREOF; BIOCIDES, e.g. AS DISINFECTANTS, AS PESTICIDES OR AS HERBICIDES; PEST REPELLANTS OR ATTRACTANTS; PLANT GROWTH REGULATORS
  • A01N59/00—Biocides, pest repellants or attractants, or plant growth regulators containing elements or inorganic compounds
  • A01N59/16—Heavy metals; Compounds thereof
  • A01N59/20—Copper
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K33/00—Medicinal preparations containing inorganic active ingredients
  • A61K33/24—Heavy metals; Compounds thereof
  • A61K33/245—Bismuth; Compounds thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K33/00—Medicinal preparations containing inorganic active ingredients
  • A61K33/24—Heavy metals; Compounds thereof
  • A61K33/30—Zinc; Compounds thereof
• • A—HUMAN NECESSITIES
  • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
  • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
  • A61K33/00—Medicinal preparations containing inorganic active ingredients
  • A61K33/24—Heavy metals; Compounds thereof
  • A61K33/38—Silver; Compounds thereof
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
  • C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
  • C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
  • C03C8/20—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions containing titanium compounds; containing zirconium compounds
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B33/00—Clay-wares
  • C04B33/32—Burning methods
  • C04B33/34—Burning methods combined with glazing
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/0072—Heat treatment
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/009—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone characterised by the material treated
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/4505—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements characterised by the method of application
  • C04B41/4535—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements characterised by the method of application applied as a solution, emulsion, dispersion or suspension
  • C04B41/4539—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements characterised by the method of application applied as a solution, emulsion, dispersion or suspension as a emulsion, dispersion or suspension
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
  • C04B41/5022—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with vitreous materials
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
  • C04B41/5025—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with ceramic materials
  • C04B41/5027—Oxide ceramics in general; Specific oxide ceramics not covered by C04B41/5029 - C04B41/5051
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
  • C04B41/5025—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with ceramic materials
  • C04B41/5041—Titanium oxide or titanates
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
  • C04B41/5025—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with ceramic materials
  • C04B41/5049—Zinc or bismuth oxides
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/45—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements
  • C04B41/50—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials
  • C04B41/5025—Coating or impregnating, e.g. injection in masonry, partial coating of green or fired ceramics, organic coating compositions for adhering together two concrete elements with inorganic materials with ceramic materials
  • C04B41/505—Tin oxide
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
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  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
  • C04B41/81—Coating or impregnation
  • C04B41/85—Coating or impregnation with inorganic materials
  • C04B41/86—Glazes; Cold glazes
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B41/00—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone
  • C04B41/80—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics
  • C04B41/91—After-treatment of mortars, concrete, artificial stone or ceramics; Treatment of natural stone of only ceramics involving the removal of part of the materials of the treated articles, e.g. etching
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2204/00—Glasses, glazes or enamels with special properties
  • C03C2204/02—Antibacterial glass, glaze or enamel
• • C—CHEMISTRY; METALLURGY
  • C03—GLASS; MINERAL OR SLAG WOOL
  • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
  • C03C2209/00—Compositions specially applicable for the manufacture of vitreous glazes
• • C—CHEMISTRY; METALLURGY
  • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
  • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
  • C04B2237/00—Aspects relating to ceramic laminates or to joining of ceramic articles with other articles by heating
  • C04B2237/30—Composition of layers of ceramic laminates or of ceramic or metallic articles to be joined by heating, e.g. Si substrates
  • C04B2237/32—Ceramic

Definitions

• the present invention relates to the field of antimicrobial protection in a ceramic article or component thereof. More specifically, the present invention relates to a composition for imparting built-in and long lasting antimicrobial characteristics to ceramic products.
• Ceramic coatings are commonly used in products that store, treat, or transport water and liquid waste. Ceramic toilets, urinals, bidets, bathroom basins (collectively known as sanitary ware), flooring tiles and other bathroom fixtures are probably the most common example of such products.
• Zinc oxide is known as having antimicrobial characteristics and has been used in the preparation of ceramic glazing compositions.
• known ceramic glazing compositions that rely solely upon zinc oxide as an antimicrobial agent have not shown antimicrobial efficacy sufficient for control of microbial growth and proliferation on ceramic surfaces.
• microbe or “microbial” should be interpreted to refer to any of the microscopic organisms studied by microbiologists or found in the use environment of a ceramic article or ceramic-glazed article. Such organisms include, but are not limited to, bacteria and fungi as well as other single-celled organisms such as mold, mildew and algae. Viral particles and other infectious agents are also included in the term microbe.
• antimicrobial and like terms should be interpreted as encompassing both microbe-killing as well as microbistatic activities. That is, it herein is considered efficacious if an antimicrobial composition reduces the number of microbes on a substrate or it the composition retards the normal rate of microbial growth.
• microbes and antimicrobial to denote a broad spectrum activity (e.g. against bacteria and fungi).
• efficacy against a particular microorganism or taxonomic rank the more focused term will be used (e.g. antifungal to denote efficacy against fungal growth in particular).
• a first embodiment is an antimicrobial ceramic glaze composition.
• a second embodiment disclosed herein is a method for making an antimicrobial ceramic glazing composition.
• the glaze composition comprises a plurality of conventional glaze ingredients and a combination of antimicrobial agents, as described more fully below.
• Glazes are generally made from powdered glass combined with colored oxides of such elements as cobalt, chrome, manganese, or nickel.
• the powder mixture is suspended in water and applied to the ceramic surface by spraying, brushing, dipping, or other known application methods.
• the suspension, or slip, in which the glaze is applied to the ceramic surface must have particular properties to ensure that the glaze is easy to apply, does not run during firing, and adheres well both when wet and after firing.
• slip properties are often obtained by adding a small amount of clay to the suspension and by controlling both the amount of water in the slip as well as the size of the powder particles.
• Organic surface-active agents e.g. surfactants, detergents
• surfactants e.g. surfactants, detergents
• Colors in glazes are controlled by adding coloring agents to the glassy components of the glaze. Special effects in glazes can also be produced. If salt is added to the kiln during firing, the glaze develops a fine orange-peel texture, which can be uniform or spotty depending upon conditions. A glaze that froths during firing gives a rough surface of broken bubbles known as a blister glaze.
• baseline glaze composition that is, a conventional, non-antimicrobial ceramic glaze base—and methodology to aid in identification of suitable and efficacious antimicrobial agents.
• baseline glaze that is, a conventional, non-antimicrobial ceramic glaze base
• a conventional glaze composition used for experimental trials herein is composed of 95% slow-fire base glaze (containing primarily SiO 2 and secondarily, inter alia, KNaO, CaO, BaO, SrO Al 2 O 3 and B 2 O 3 ).
• Alkaline earth oxide materials such as calcium carbonate, wollastonite, and zinc oxide are generally added as raw materials.
• Other alkaline earth oxides such as lead oxide, strontium oxide, barium oxide, and magnesium oxide are more typically added in a fritted form.
• the alkaline earth oxides are advantageous because they provide fluxing action without having a major effect on glaze thermal expansion. Oxides also can serve as coloring compounds.
• EPK kaolin a dry material that is blended into a sufficient quantity of de-ionized water to produce a glaze slip with a specific gravity of 1.35 ⁇ 0.05 g/cc. This represents a solids content of 41.74%.
• Bentonite an absorbent aluminum silicate clay formed from volcanic ash and well known to those of skill in the ceramic art. This dry material is blended into a sufficient quantity of de-ionized water to produce a glaze slip with a specific gravity of 1.35 ⁇ 0.05 g/cc. This represents a solids content of 41.74%.
• An antimicrobial glazing composition was made by adding together (e.g. by mixing) conventional glazing composition components and antimicrobial agent combinations.
• the components and antimicrobial agent(s) were added based on weight of the solids content of the baseline glaze, excluding such antimicrobial agent(s).
• the glaze base is described in greater detail above.
• the glaze base with antimicrobial agent(s) admixed therein, then was ball milled for fifteen minutes.
• the milled glaze base was held overnight to allow for hydration, then remixed.
• the antimicrobial glazing composition then was ready to be applied to a substrate (e.g. a bisque tile).
• a method of affixing a ceramic glaze to a substrate confers durable antimicrobial properties to the substrate.
• the method generally comprises providing a ceramic glazing composition having one or more antimicrobial agents disposed therein as set forth in the present disclosure, applying the antimicrobial glazing composition to a substrate, and curing the glazing composition in accordance with conventional glaze-firing techniques.
• the powdered glass softens and largely equilibrates over the ceramic surface, reacting with the ceramic substrate to form a strong, adherent union therewith. If a glaze is applied to an already fired ceramic substrate, a second firing is necessary to melt and bond the glaze to the substrate. Alternatively, it is possible to apply a glaze to an unfired ceramic and fire both the glaze and substrate together.
• Various components such as alkali oxide, borates, and lead oxide can be added to the ceramic glaze composition to facilitate softening at lower temperatures in order that the glaze flow more easily during firing and to minimize roughness and defects in the fired ceramic glaze surface.
• the present antimicrobial combinations are compatible with these common additives.
• the initial stage of a typical ceramic production process is the production of barbotine or slip, a clay from which bathroom ceramic products are made.
• Barbotine is made from a mixture of clays, kaolin, phyllites, feldspar and quartz.
• Parts are formed by filtering water contained in the barbotine clay through micropores in the resin molds by the application of pressure. The water is eliminated by injecting compressed air along the molds.
• the parts After casting and removal from the molds, the parts go for drying in kilns under controlled humidity and temperature (approximately 90.degree. C.). The drying cycle lasts about 7 hours, reducing the water content of the part from about 16% to less than 1%. Following this, the parts are inspected to detect possible flaws. The parts then go to the coating process.
• the coating process is alternatively referred to as the glazing step.
• the glazing step typically comprises the application of ceramic glaze on the parts using guns in individual booths fitted with exhaust systems and water curtains.
• Typical ceramic glaze is produced from a mixture of kaolin, feldspar, quartz, colorings and other additives.
• the parts are fired in continuous kilns, reaching temperatures of about 1250° C. in an approximately 15-hour cycle. The firing process gives the glazed part the color and transparent appearance that is typical of vitreous china.
• Each dipped tile was placed into a tile sagger, each sagger capable of holding up to twenty tiles.
• the sagger was placed into one of the two electric kilns and fired to a Pyrometric Cone Equivalent of 06. This measure of thermal history is roughly equivalent to 1889° F. or 1062° C. Baseline glaze samples were fired at temperatures ranging from 1888° F. to 2194° F.
• the above procedure approximates a glaze application in a production environment.
• the final baseline glaze formulations resulted in samples having a glassy surface at a low temperature, highly resistant to absorption of dyes, and exhibiting no antimicrobial properties.
• the baseline samples are the foundation for comparing and judging the candidate materials.
• the adopted baseline glaze is simple in composition, easy to process and apply, and has a low firing temperature. These attributes greatly facilitated the evaluation of candidate material samples.
• this dried glaze layer is about 2 millimeters in thickness.
• a more cost efficient method of producing an antimicrobial surface would entail use of a much thinner secondary glaze applied over the regular (first) glaze.
• This glaze thickness could be 0.5 millimeters or less in thickness.
• a ceramic article bearing the above-described antimicrobial glaze composition exhibits durable antimicrobial properties.
• the antimicrobial ceramic article comprises a substrate, for example a ceramic substrate, having at least a first surface; and a fired or cured glaze disposed on at least a portion of the first surface.
• the ceramic glazing composition utilized in this embodiment is the same as that described in the first embodiment.
• Antimicrobial agents were used to manufacture a range of antimicrobial glaze compositions, each composition consisting of one, two or three antimicrobial agents.
• Several ceramic articles then were prepared to test the antimicrobial characteristics of the recited glazes.
• the test articles comprised an underlying ceramic substrate made from a standard commercial barbotine.
• the glaze used in the testing was the baseline glaze described previously, to which was added varying quantities of antimicrobial agent combinations as noted.
• the glaze composition was applied to the articles by dipping, and the test articles were then fired.
• the combination of 4% Ag 2 CO 3 and 4% ZnO was not tested, as 4%/4% combinations generally are considered too expensive to be commercialized and/or are have been observed to negatively affect the aesthetics of the glaze finish. It is expected that such combinations would show efficacy if the 2%/4% and/or 4%/2% combination was efficacious, although antagonistic effects have been observed for some combinations.
• Test articles also were prepared without any antimicrobial agents in the glaze for use as a negative control.
• the measure of antimicrobial efficacy is the reduction in the number of organisms surviving the testing protocol in comparison with the baseline standard. Minimum efficacy is assumed to originate at a reduction level of 1 common logarithm (log (NOS Std/NOS Sample)).
• Sample tile pieces having a diameter of approximately 55 mm were used. Ceramic glaze composition was applied and fired according to the instructions for the commercial glaze base employed. This preparation process yielded test disks having about a top surface area of about 2500 square millimeters.
• the comparison test for antimicrobial efficacy used Klebsiella pneumoniae , ATCC 4352.
• the test organism was grown, and a portion of an exponentially growing culture was collected into Japanese Nutrient Broth (JNB) diluted 1/500.
• JNB Japanese Nutrient Broth
• An inoculum was prepared at about 10 6 colony-forming units (CFU) per milliliter by dilution with 1/500 JNB.
• test inoculum ⁇ 0.8 ⁇ 10 5 CFU
• cover slip or film was placed over and in contact with the inoculum to ensure uniform and substantially complete coverage of the inoculum over the sample surface.
• the culture plate then was incubated for 24 hours at 37° with humidity.
• Bacteria on the sample and cover slip/film were recovered, collected into D/E Neutralizing Broth, and counted.
• the antimicrobial activity of the test samples is expressed herein as a log reduction value, as compared to the bacterial growth of the corresponding untreated (control) sample.
• a log reduction is expressed as log(U/B), where U is the average CFU of the test organism from the inoculum recovered in the Neutralizing Broth from the negative control (untreated) sample tile, and B is the average CFU of the test organism recovered in the Neutralizing Broth from the inoculated sample.
• 2% Ag 2 CO 3 was utilized as a first antimicrobial agent in a family of glaze compositions, which further contained a second antimicrobial agent: one of Bi 2 O 3 , CuO, SnO 2 , TiO 2 or ZnO.
• the second antimicrobial agent was tested at both 2% and 4%. Sample tiles were glazed and the tiles were evaluated according to the above-described modified JIS Z2801:2000 test protocol for the effect of the glazed tile on bacterial reduction. Results are shown in TABLE 1.
• 2% Bi 2 O 3 was utilized as a first antimicrobial agent in a family of glaze compositions, which further contained a second antimicrobial agent: one of Ag 2 CO 3 , CuO, SnO 2 , TiO 2 or ZnO.
• the second antimicrobial agent was tested at both 2% and 4%. Sample tiles were glazed and the tiles were evaluated according to the above-described modified JIS Z2801:2000 test protocol for the effect of the glazed tile on bacterial reduction. Results are shown in TABLE 2.
• 2% CuO was utilized as a first antimicrobial agent in a family of glaze compositions, which further contained a second antimicrobial agent: one of Ag 2 CO 3 , Bi 2 O 3 , SnO 2 , TiO 2 or ZnO.
• the second antimicrobial agent was tested at both 2% and 4%. Sample tiles were glazed and the tiles were evaluated according to the above-described modified JIS Z2801:2000 test protocol for the effect of the glazed tile on bacterial reduction. Results are shown in TABLE 3.
• 2% SnO 2 was utilized as a first antimicrobial agent in a family of glaze compositions, which further contained a second antimicrobial agent: one of Ag 2 CO 3 , Bi 2 O 3 , CuO, TiO 2 or ZnO.
• the second antimicrobial agent was tested at both 2% and 4%. Sample tiles were glazed and the tiles were evaluated according to the above-described modified JIS Z2801:2000 test protocol for the effect of the glazed tile on bacterial reduction. Results are shown in TABLE 4.
• 2% TiO 2 was utilized as a first antimicrobial agent in a family of glaze compositions, which further contained a second antimicrobial agent: one of Ag 2 CO 3 , Bi 2 O 3 , CuO, SnO 2 or ZnO.
• the second antimicrobial agent was tested at both 2% and 4%. Sample tiles were glazed and the tiles were evaluated according to the above-described modified JIS Z2801:2000 test protocol for the effect of the glazed tile on bacterial reduction. Results are shown in TABLE 5.
• 2% ZnO was utilized as a first antimicrobial agent in a family of glaze compositions, which further contained a second antimicrobial agent: one of Ag 2 CO 3 , Bi 2 O 3 , CuO, SnO 2 or TiO 2 .
• the second antimicrobial agent was tested at both 2% and 4%. Sample tiles were glazed and the tiles were evaluated according to the above-described modified JIS Z2801:2000 test protocol for the effect of the glazed tile on bacterial reduction. Results are shown in TABLE 6.
• An additive (neutral) effect has no economic advantage over the individual antimicrobial agents.
• An antagonistic effect would produce a negative or reduced-efficacy result.
• the combinations identified below demonstrate an unexpected and synergistic antimicrobial effect in a fired ceramic glaze.
• the combinations of first and second antimicrobial agents, as described herein, achieve superior antimicrobial activity at lower antimicrobial agent concentrations as compared to the antimicrobial capability of either antimicrobial agent alone. Such a superior effect presents a distinct economic advantage and increases the effectiveness of the antimicrobial combination per unit weight.
• twice the level of the second antimicrobial agent displays an antagonistic effect, wherein the observed efficacy is lower than both (a) the expected additive log reduction value for [2% Ag 2 CO 3 +4% Bi 2 O 3 ]; and (b) the observed log reduction value for the [2% Ag 2 CO 3 +2% Bi 2 O 3 ] combination.
• the [2% Ag 2 CO 3 +2% CuO] combination exhibits a strong synergistic effect relative to the expected results based on merely additive principles.
• Increasing the level of the second antimicrobial agents two-fold that is, [2% Ag 2 CO 3 +4% CuO] destroys the synergistic effect, instead resulting in antagonism: the observed efficacy of the [2% Ag 2 CO 3 +4% CuO] combination (3.8) is essentially the same as the [2% Ag 2 CO 3 +2% CuO] combination (3.9/3.8) and well below the very high expected log reduction for this combination.
• Ag 2 CO 3 and SnO 2 demonstrated surprising and strong synergy for the [2% Ag 2 CO 3 +2% SnO 2 ] combination (3.2 log reduction).
• the combination of Ag 2 CO 3 and SnO 2 showed marked antagonism when the SnO 2 concentration was doubled to 4%: log reduction tumbled to 1.9, well below both the observed result of 3.2 for the [2% Ag 2 CO 3 +2% SnO 2 ] combination as well as the expected additive result.
• tertiary combinations comprise Bi 2 O 3 , ZnO and Ag 2 CO 3 .
• Concentrations of the individual compounds in the tertiary combinations trialed include Bi 2 O 3 at 1% and 2%; at ZnO at 1% and 2%; and Ag 2 CO 3 at 0.5%, 1% and 2%.
• the tertiary combination data show that the three components were efficacious when present in the ceramic glaze composition at equal concentrations of 1%.
• Tertiary antimicrobial agent combinations in which an increase to 2% of one or both of the Bi 2 O 3 concentration and the ZnO concentration likewise demonstrated efficacy against the bacterial inoculum.
• Antimicrobial activity was greatest for the tertiary combination containing 2% each of Bi 2 O 3 , Ag 2 CO 3 and ZnO. The strength of the antimicrobial activity for this combination exceeds that expected based on the performance of the component antimicrobial agents individually.
• the antimicrobial ceramic glaze was designed to impart durable (persistent) and built-in antimicrobial protection to a variety of ceramic articles. Accordingly, the scope of the disclosure includes ceramic articles that incorporate the present antimicrobial glazing. Such articles include, but are not limited to, toilets, bidets, washbasins, towel rails, soap holders, toilet roll holders, water control fixtures (e.g., hot and cold water handles), and ceramic glazed tiles.

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