Patent Application
20050129937
Reference is made to commonly assigned, copending applications U.S. Ser. No. ______ (docket 87305) entitled ANTIMICROBIAL ARTICLE WITH DIFFUSION CONTROL LAYER by Bringley et al., and U.S. Ser. No. ______(Docket 87099) entitled ANTIMICROBIAL COMPOSITION by Bringley, et al. filed concurrently herewith.
The present invention relates to a medium containing a controlled release antimicrobial material and/or that changes visual appearance as the material reaches a predetermined state. The medium also has an adhesive layer so it can be adhered to a surface such as a counter top.
In recent years people have become very concerned about exposure to the hazards of bacterial contamination. For example, exposure to certain strains of Eschericia coli through the ingestion of under cooked beef can have fatal consequences. Exposure to Salmonella enteritidis through contact with unwashed poultry can cause severe nausea and exposure to Staphylococcus aureus, Klebsiella pneumoniae, yeast (Candida albicans) can cause skin infections. In some instances bacterial contamination alters the taste of the food or drink or makes the food unappetizing. With the increased concern by consumers, manufacturers have started to produce products having antimicrobial properties. The most common antimicrobial used in many of these products is triclosan. Triclosan has proven to be effective only under certain conditions and in a limited number of products and does not kill a wide range of bacteria. It also lacks thermal stability, which causes it to leach out of rubber and rubber-like materials at higher temperatures.
In the area of food preparation, counter tops, table and cabinets are made using high-pressure laminates as discussed in U.S. Pat. No. 6,248,342. When used in food preparation areas, high-pressure laminates often come in contact with food and are a breeding ground for bacteria, fungi, and other microorganisms. Therefore, attempts have been made to develop high-pressure laminates having antimicrobial properties. For example, the organic compound triclosan has been incorporated in countertops in an attempt to provide a surface having antimicrobial properties. However, microorganisms can develop resistance to organic compounds such as triclosan. Moreover, the antimicrobial effects of triclosan decline over time as triclosan leaches out from the surface of the substrate, and there is no visual indication of the decline of the effectiveness. Because laminated countertops are an integral part of the cabinet, they are expensive to replace. In addition, triclosan is believed to cause skin irritation. Furthermore, triclosan is believed to generate dioxin when burned, creating disposal problems.
Nobel metal ions such as silver and gold ions are known for their anti-microbial activities and have been used in medical care for many years to prevent and treat infection.
Patents U.S. Pat. No. 5,556,699 and U.S. Pat. No. 6,436,422 disclose antibiotic materials containing zeolites for use as materials for packaging foods, medical equipments and accessories. U.S. Pat. No. 6,555,599 discloses an antimicrobial vulcanized EPDM rubber-containing article having sufficient antimicrobial activity and structural integrity to withstand repeated use without losing either antimicrobial power or modulus strength.
There is a problem in that antimicrobial films may quickly be depleted of antimicrobial active materials and become inert or non-functional. Depletion results from rapid diffusion of the active materials into the biological environment with which they are in contact. There is a further problem in that it is heretofore impossible to distinguish a depleted or inactive film from a working film using common human senses such as sight, smell or touch. Thus, users are unable to determine if a surface is antimicrobially safe for continued operation. When surface such as countertops lose this effectiveness in preventing bacterial growth, they are expensive and difficult to replace.
There remains a need to provide a perceivable indication to the user that the antimicrobial material is depleted or has worn away, thus prompting the user that the film needs to be replaced. The film also can be easily applied to a surface such as a countertop or other work surface and easily removed when the antimicrobial properties have been depleted.
In accordance with one aspect of the present invention, there is provided a flexible multi-layer medium comprising:
a flexible support layer having a first side and a second side;
a flexible antimicrobial layer adjacent the first side of the support layer; and
a flexible adhesive layer adjacent the second side of the support layer.
In accordance with another aspect of the present invention there is provided a multi-layer medium comprising:
a support layer having a first side and a second side;
a antimicrobial layer adjacent the first side of the support layer, the antimicrobial layer having an indicating means for providing a visual indication of the effectiveness of the antimicrobial layer; and
an adhesive layer adjacent the second side of the support layer.
In accordance with yet another aspect of the present invention, there is provided an antimicrobial medium having a visual indicator for indicating the loss of effectiveness of the antimicrobial medium.
In yet still another aspect of the present invention, there is provided a multi-layer medium comprising:
a support layer having a first side and a second side;
a antimicrobial layer adjacent the first side of the support layer having controlled release of the active antimicrobial ingredient in the antimicrobial layer, and
an adhesive layer adjacent the second side of the support layer.
In accordance with still another aspect of the present invention, there is provided an antimicrobial material for detecting exposure to a pathogen, comprising an antimicrobial metal ion exchange material which is exchanged with at least one colored metal ion or colored metal ion complex.
These and other aspects, objects, features and advantages of the present invention will be more clearly understood and appreciated from a review of the following detailed description of the preferred embodiments and appended claims, and by reference to the accompanying drawings.
In the detailed description of the preferred embodiments of the invention presented below, reference is made to the accompanying drawings in which:
Referring to
The antimicrobial active material of antimicrobial layer 15 may be selected from a wide range of known antibiotics and antimicrobials. An antimicrobial material may comprise an antimicrobial ion, molecule and/or compound, metal ion exchange materials exchanged or loaded with antimicrobial ions, molecules and/or compounds, ion exchange polymers and/or ion exchange latexes, exchanged or loaded with antimicrobial ions, molecules and/or compounds. Suitable materials are discussed in “Active Packaging of Food Applications” A. L. Brody, E. R. Strupinsky and L. R. Kline, Technomic Publishing Company, Inc. Pennsylvania (2001). Examples of antimicrobial agents suitable for practice of the invention include benzoic acid, sorbic acid, nisin, thymol, allicin, peroxides, imazalil, triclosan, benomyl, metal-ion release agents, metal colloids, anhydrides, and organic quaternary ammonium salts. Preferred antimicrobial reagents are metal ion exchange reagents such as silver sodium zirconium phosphate, silver zeolite, or silver ion exchange resin which are commercially available. The antimicrobial layer 15 generally has a thickness “y” of between 0.1 microns and 100 microns, preferably in the range of 1.0 and 25 microns. In the embodiment illustrated the thickness “y” is about 5 microns.
The adhesive used to form the adhesive layer 20 is typical of the adhesive layer found on the back shelving papers such as a reposition adhesive such as the adhesive used in 3M™ Scotch® 859 Removable Mounting Squares and 3M™ Scotch® Repositionable Glue Tape 928-100.
In another embodiment of the antimicrobial multilayer medium 5, the adhesive layer 20 may be a flexible static-cling vinyl such as Trans-Flex-Cast commercially available from Transilwrap Co., Inc., 9201 W. Belmont Ave., Franklin Park, Ill.
A second embodiment of the antimicrobial multilayer medium 5, made in accordance the present invention, is shown in
Depending upon the material chosen for the support layer, an additional layer called a subbing layer 40 may be coated on the top surface 18 of the support layer 10. The subbing layer 40 is used to insure proper adhesion of the antimicrobial layer 15 to the support layer 10. Likewise, a subbing layer 45 maybe coated on the bottom surface 22 of the support layer 10. The subbing layer 45 is used to insure proper adhesion of an adhesive layer 20 to the support layer 10. As previously discussed, depending on what material is used for the base 10, the subbing layer 45 may or may not be required. Preparing a support surface (hydrophobic) such as polyvinyl alcohol to accept a solvent cast polymer such as cellulose triacetate would require chemical and/or an interlayer coating (subbing layer) to improve adhesion. An example of this could be found in photographic patent literature where gelatin based hydrophilic photographic materials are commonly attached to hydrophobic supports such as polyethylene terephthalate. In the embodiment illustrated, an optional peelable protective release layer 50 is provided over adhesive layer 20 for protecting the adhesive layer 20 until it is to be used for securing the multilayer medium 5 to a surface. Preferred protective release materials include polyester, cellulose paper, and biaxially oriented polyolefin. The release layer 50 is peeled off the adhesive layer 20 as indicated by arrow 52 whereby the multilayer medium 5 is secured to the desired surface.
A web (not shown) of the antimicrobial medium 5 can be made by several possible methods. In one embodiment, the antimicrobial web is made by coating the surface 18 of a plastic, paper or fabric support 10 with a polymeric layer containing one or more antimicrobial compounds. The antimicrobial is typically dispersed or dissolved in a medium or solvent. The medium or solvent may contain a binder to allow the antimicrobial to adhere to the support 10 and may contain other addenda such as coating aids, surfactants, plasticizers, etc. to aid the coating process. The coating may be applied by painting, spraying or casting. It is preferred to apply the coating via a solvent assisted process (aqueous or organic) such as blade, rod, knife or curtain coating. The antimicrobial web may also be made by extrusion, or coextrusion of polymeric layers such that at least one layer comprises an antimicrobial compound and the color indicating chemistry described below. The antimicrobial web may also be prepared by blow molding.
Now referring to
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In a preferred embodiment, the multilayer medium 5 contains an antimicrobial material comprising a metal ion exchange material which is exchanged with at least one antimicrobial metal ion selected from silver, copper, gold, nickel or zinc, and is additionally exchanged with at least one colored metal ion, or colored metal ion complex. The colored metal ion or metal ion complex may be antimicrobial or may be inert. The colored metal ion or metal ion complex imparts color to the antimicrobial sheet and upon exposure to a biological medium, diffuses into the medium, and is depleted in the same manner that the antimicrobial metal ion is depleted. As the colored metal ion or colored metal-ion complex is depleted, the web changes color. The amount of exchanged colored metal ion or metal ion complex is determined such the rate of depletion of the colored metal ion is similar to the rate of depletion of the antimicrobial metal ion, and thus, the loss of color from the web indicates a loss of antimicrobial activity. In a further preferred embodiment, the antimicrobial material consists of metal ion exchanged zirconium phosphate, zeolite or other metal ion exchanged resin, which is exchanged with at least one antimicrobial metal ion selected from silver, copper, gold, nickel or zinc, and is additionally exchanged with at least one highly colored metal ion or metal ion complex. Colored metal ions or metal ion complexes suitable for practice of the invention are Cu(II), Co(II), Co(HII), Ni(II), Manganese ion, Cr(III), Fe(II), Fe(III), Ni(II) and metal ion complexes such as Co(NH3)63+, Cu(NH3)42+.
Alternatively, color indication can be provided in the diffusion control layer 30 shown in
Another approach to providing color indication for the antimicrobial web is to incorporate a colorless, or colored, precursor material which then reacts with a diffusible species such as antimicrobial ions, to form a colored molecule or material, or a material of a different color than the precursor. In this manner, as more antimicrobial ions diffuse through the web, more dye is produced thus producing a visual color indication. In a preferred embodiment the dye precursor is contained in the diffusion control layer 30 and reacts with diffusing antimicrobial metal ions selected from silver, copper, gold, zinc and nickel to produce a colored material. A working example of the color indicating chemistry 70 is illustrated below in which a metalized dye is formed by reaction of a metal ion with the ligand, 2-methyl-5-hydroxy-8-(2-pyridylazo)-quinoline-3-carboxylic acid. The reaction forms a very highly colored dye having the stoichiometry M(ligand) or M(Ligand)2. Examples of suitable metal ions are copper, zinc, cobalt and nickel.
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Yet another embodiment of the present invention is illustrated in
It is to be understood that various other changes and modifications may be made without departing from the scope of the present invention, the present invention being defined by the following claims.
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