Antimicrobial insert device for water-bearing appliance

ANTIMICROBIAL INSERT DEVICE FOR WATER-BEARING APPLIANCE

0002BACKGROUND OF THE INVENTION [0001] Field of the Invention [0002] The present invention relates to an antimicrobial household appliance, and more particularly to an antimicrobial insert device suitable for placement within a liquid-bearing household appliance to confer an antimicrobial property thereon. [0003] Background of the Prior Art [0004] Liquid residue frequently may collect within some domestic appliances, such as washing machines, dishwashers, refrigerators, cooking devices (e.g., a rice cooker or vegetable steamer) and the like. During prolonged periods of nonuse, bacteria, fungi, or other microbiological species may colonize within the appliance, especially in liquid-covered or liquid- retaining areas. This colonization may lead to contamination of articles placed in the appliance when next used and also to production of unpleasant odors.

0003[0005] With dishwashers in particular, this problem is mainly caused by stagnant water remaining in the sump of the dishwasher. Even after drain- age, stagnant water often is mixed with particulates, food matter and other organic residue. This combination can nourish and support the growth of bacteria or fungi. In a particularly undesirable outcome, a slimy and odorous build-up may cover the sump surface. Such build-up generally is quite difficult to remove. DESCRIPTION OF THE PREFERED EMBODIMENTS [0006] As used herein, the terms "microbe" or "microbial" should be interpreted to encompass any of the microscopic organisms commonly studied by microbiologists. 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. [0007] The term "antimicrobial" includes biostatic activity, i.e., where the proliferation of microbiological species is reduced or eliminated, and true biocidal activity where microbiological species are killed. For ease of discussion, this detailed description may make reference to bacteria and antibacterial agents. This method of presentation should not be interpreted as limiting the scope of the invention in any way. [0008] The terms "efficacy" and "efficacious" are defined as a biostatic characteristic, such as inhibiting the growth of a microbe on a substrate. [0009] The term "non-metallic" means antimicrobial agents, other than quaternary ammonium compounds, that do not contain or utilize metal ions such as, for example, silver or copper. [0010] An antimicrobial device as described herein comprises a device body and an antimicrobial agent disposed therein or affixed thereto. [0011] In a first embodiment, the antimicrobial insert device is constructed of a polymeric material and has incorporated therein one or more antimicrobial agents. In one illustrative example, a toroid (i.e., three-dimensional ring or "doughnut") body can be manufactured of a polymer such as polypropylene. An antimicrobial agent can be incorporated within the polymer matrix of the ring body of the device.

0004[0012] In a preferred but not required version of this embodiment, the an- timicrobial agent is disposed within the antimicrobial insert device so as to be differentially concentrated near the surface of the device, as will be more fully described below.

0005[0013] In a second embodiment, an antimicrobial agent can be affixed to a surface of the antimicrobial device. For example, a coating layer can be applied to the surface of the insert device body.

0006[0014] Alternatively, the insert device body can be manufactured by co- extrusion, wherein the antimicrobial agent is disposed within one portion of the co-extruded structure. In a selected sub-embodiment, the antimicrobial agent is disposed in the outer portion of the co-extruded insert body. [0015] Co-extrusion permits selection of polymers that can, for example, facilitate retention of the insert device in the inserted location. For example, a dense polymer core can be selected to prevent flotation of the insert device (that is, a polymer having a specific gravity greater than 1.0), while an outer or sheath portion of the insert device can be constructed of a less dense polymer. Manufacturing costs also can factor into the choice of polymers for a co-extruded structure.

0007[0016] In a third embodiment of the insert device, a structural element thereof comprises a plurality of antimicrobial agents. In one illustrative example, an effective antibacterial agent and an effective antifungal agent can be combined. The combination may impart to the element a broader antimicrobial character than either antimicrobial agent alone may provide. Alternatively or additionally, such a combination may be equally efficacious in combating microbes and also more desirable from a cost perspective. [0017] Construction materials may include plastics such as polyethylene, polypropylene, polyesters, polyamides, polystyrene, and/or acrylic polymers. Also suitable are copolymers having incorporated therein a polymer such as listed above. The specific material from which an appliance sump or interior structural element (e.g., panel piece, sump part) can be constructed are known to those of skill in the art.

0008[0018] Suitable polymeric resins include, without limitation, polypropylene; polyethylene including LDPE, MDPE, HDPE and other known poly- ethyenes); polystyrene; acrylonitrile butadiene styrene; polyvinyl chloride; ethyl vinyl acetate; foam thermoplastic urethane; styrene-butadiene rubber; vinyl; nylon; polycarbonate; polyolefin; and polyurethane.

0009[0019] An antimicrobial agent is used to prevent or control microbial colonization. Prevention or control of colonization of bacteria, fungi, and other microbes likewise reduces or eliminates microbial deposits and disagreeable odors. [0020] The antimicrobial agents useful with the above compositions include substituted or unsubstituted phenols; quaternary ammonium compounds, gentian violet compounds, biguanide compounds, iodine compounds, and mixtures thereof. [0021] Exemplary substituted or unsubstituted phenols include, without limitation: phenol; mono- and poly-chlorophenols; cresols; 4-chloro-3- methylphenol; 3,5-dimethyl-4-chlorophenol; thymol; 4-chlorothymol; 4-t- amylphenol; saligenin; ortho-phenyl phenol;; 4-n-hexylresorcinol; carvacrol; 2-phenylphenol; 2-benzyl-4-chlorophenol; 2,2'-dihydroxy-5,5'- dichlorodiphenylmethane; 2,4,4'-trichloro-2-hydroxydiphenyl ether; 2,2'- dihydroxy-3,3',5,5',6,6'-hexachlorodiphenylmethane; 2,2'-dihydroxy-5,5'- dichlorodiphenyl sulphide; 2,2'-dihydroxy-3,3',5,5'-tetrachlorodiphenyl sulphide; 2-hydroxy-2',4,4'-trichlorodiphenyl ether; dibromosalicyl; 3,5-dimethyl- 4-chlorophenol (chloroxylenol); thymol (isopropyl-m-cresol); and mixtures thereof.

0010[0022] Examplary quaternary ammonium compounds include, without limitation: alkyl-dimethyl-benzylammonium chloride; alkyl-dimethyl- ethylbenzylammonium chloride; dodecyl-dimethyl-3,4- dichlorobenzylammonium chloride; dodecyl-di-(2-hydroxyethyl)- benzylammonium chloride; dodecyl-di-(2-hydroxyethyl)-benzylammonium pentachlorophenolate; dodecyl-di-(2-hydroxyethyl)-benzylammonium A- methylbenzoate; dodecyl-dimethyl-phenoxyethylammonium bromide; A- diisobutyl-phenoxyethoxyethyl-dimethylbenzylammonium chloride; A- diisobutyl-cresoxyethoxyethyl-dimethylbenzylammonium chloride; dimethyl- didecylammonium chloride; cetyl-trimethylammonium bromide; dodecyl- pyridinium chloride; cetyl pyridinium chloride; dodecyl-isoquinolinium chloride; decamethylene-bis-4-aminoquinaldinium dichloride; alpha-(p-tolyl)- dodecyl-trimethyl-ammonium methosulphate; (dodecanoyl-N- methylaminoethyl)-(phenylcarbamoylmethyl)-dimethylammonium chloride; cetyl pyridinium chloride (1 -hexadecylpyridinium chloride); and mixtures thereof.

0011[0023] A non-exhaustive list of gentian violet compounds include gentian violet and dimethyl gentian violet.

0012[0024] Biguanide compounds include, for example, poly(hexamethylene- biguanide hydrochloride); poly(iminocarbonimidoyliminocarbonimidoylimino- 1 ,6-hexanediyl), hydrochloride; poly(iminoimidocarbonyl-iminoimidocarbonyl- iminohexamethylene) hydrochloride; poly(iminoimidocarbonyliminoimido- carbonylimino hexamethylene monohydrochloride); poly(iminoimido- carbonyliminoimidocarbonyliminohexamethylene) hydrochloride; poly (iminimidocarbonyliminoimidocarbonyliminohexamethylene) hydrochloride, and similar compounds. [0025] Non-limiting iodine compounds can include: potassium iodate; po- tassium iodide; iodine complexes (such as KI:I2 and polyvinylpyrroli- done:iodine) and iodine (herein considered an "iodine compound"). [0026] Further antimicrobial agents amenable to use in the disclosed articles and components thereof include diiodomethyl-p-tolylsulfone; 3-iodo-2- propynyl N-butylcarbamate; azoles such as propiconazole, tebuconazole or thiabendazole; 3-benzo[b]thien-2yl-5,6-dihydro-1 ,4,2-oxathiazine 4-oxide; al- kyl dimethylbenzyl ammonium saccharinate; N-butyl-1 ,2-benzisothiazolin-3- one; 4,5-dichloro-2-octyl-3(2H)-isothiazolone; 2-n-octyl-4-isothiazolin-3-one; cyclopropyl-N'-(1 ,1 -dimethylethyl)-6-(methylthio)-1 ,3,5-triazine-2,4-diamine; 1 ,3-dicyano-2,4,5,6-tetrachlorobenzene; metals (e.g., silver, zinc, copper) in- eluding metal compounds such as silicates, zeolites, amorphous glass compositions, sol-gel compositions, and the like; zinc and copper compounds such as pyrithione; titanium dioxide; or a mixture of two or more of these compounds. [0027] Suitable antimicrobial agents for a component of the present appliance include 2,4,4'-trichloro-2'-hydroxydiphenyl ether (i.e., "triclosan"); 2- phenylphenol; poly(hexamethylene biguanide) hydrochloride; 3,4,4'- trichlorocarbanilide; titanium dioxide; barium monohydrate; zinc pyrithione derivatives; silver compounds in various forms (e.g., elemental, zeolite, amorphous glass, sol-gel formulations, and other ion-exchange formulations); copper compounds in various forms (e.g., elemental, zeolite, amorphous glass, sol-gel formulations, and other ion-exchange formulations); zinc compounds in various forms (e.g., elemental, zeolite, amorphous glass, sol- gel formulations, and other ion-exchange formulations); and isothiazolone- based compounds such as 1 ,2-benzisothiazolin-3-one; N-butyl-1 ,2- benzisothiazolin-3-one, 2-octyl-isothiazolone; 4,5-dichloro-2-N-octyl-3(2H)- isothiazolone; methyl-3(2H)isothiazolone; and chloro-2-methyl-3(2H)- isothiazolone.

0013[0028] Additional compounds that can be employed in the present insert device include the following: [0029] [0033] Fluoride:

0014[0030] [0034] Tetra-n-butylammonium Fluoride, Tetraethylammonium Fluoride [0031] [0035] Chloride: [0032] [0036] Acetylcholine Chloride, (3-

0015Acrylamidopropyl)trimethylammonium Chloride, Benzalkonium Chloride, Benzethonium Chloride, Benzoylcholine Chloride, Benzylcetyldimethylam- monium Chloride, N-Benzylcinchonidinium Chloride, N-Benzylcinchoninium Chloride, Benzyldimethylphenylammonium Chloride, Benzyldimethyl- stearylammonium Chloride, N-Benzylquinidinium Chloride, N- Benzylquininium Chloride, Benzyltri-n-butylammonium Chloride, Benzyl- triethylammonium Chloride, Benzyltrimethylamrnmonium Chloride, Carba- mylcholine Chloride, DL-Camitine Hydrochloride, Chlorocholine Chloride, (3- Chloro-2-hydroxy-n-propyl)trimethylammonium Chloride, Choline Chloride, n-Decyltrimethylammonium Chloride, Diallyldimethylammonium Chloride, Di- chloromethylenedimethylinmnium Chloride, Dimethyldistearylammonium Chloride, n-Dodecyltrimethylammonium Chloride, Girard's Reagent T, n- Hexadecyltnmethylammonium Chloride, Hexamethonium Chloride, Lauroyl- choline Chloride, Methacholine Chloride, Methacroylcholine Chloride, (2- Methoxyethoxymethyl)triethylammonium Chloride, [bgr]-Methylcholine Chloride, Methyltriethylammonium Chloride, Myristoylcholine Chloride, n- Octyltrimethylammonium Chloride, Phenyltriethylammonium Chloride, Phenyltrimethylammonium Chloride, Phosphocholine Chloride Calcium Salt, Phosphocholine Chloride Sodium Salt, Succinylcholine Chloride, Tetra-n- amylammonium Chloride, Tetra-n-butylammonium Chloride, Tetradecyldi- methylbenzylammonium Chloride, n-Tetradecyltrimethylammonium Chloride, Tetraethylammonium Chloride, Tetramethylammonium Chloride, Trimethyl[2,3-(dioleyloxy)propyl]ammonium Chloride, Trimethylstearylam- monium Chloride, Trioctylmethylammonium Chloride, Tri-n- octylmethylaimonium Chloride, [0033] [0037] Bromide:

0016[0034] [0038] Acetylcholine Bromide, Benzoylcholine Bromide, Ben- zyltri-n-butylammonium Bromide, Benzyltriethylammonium Bromide, Bromo- choline Bromide, Cetyldimethylethylamronium Bromide, Choline Bromide, Decamethonium Bromide, n-Decyltrimethylammonium Bromide, Didecyldi- methylammonium Bromide, Dilauryldimethylammonium Bromide, Di- methyldimyristylammonium Bromide, Dimethyldioctylammonium Bromide, Dimethyldipalmitylammonium Bromide, Dimethyldistearylammonium Bromide, n-Dodecyltrimethylammonium Bromide, (Ferrocenyl- methyl)dodecyldimethylammonium Bromide, (Ferrocenyl- methyl)trimethylammonium Bromide, n-exadecyltrimethylammonium Bromide, Hexamethonium Bromide, Hexyldimethyloctylammonium Bromide, n- Hexyltrimethylammonium Bromide, Methacholine Bromide, Neostigmine Bromide, n-Octyltrimethylammonium Bromide, Phenyltrimethylammonium Bromide, Stearyltrimethylammonium Bromide, Tetra-n-amylammonium Bromide, Tetra-n-butylammonium Bromide, Tetra-n-decylammonium Bromide, n-Tetradecyltrimethylammonium Bromide, Tetraethylammonium Bromide, Tetra-n-heptylammonium Bromide, Tetra-n-hexylammonium Bromide,

0017Tetramethylammonium Bromide, Tetra-n-octylammonium Bromide, Tetra-n- propylammonium Bromide, 3-(Trifluoromethyl)phenyltrimethylammonium Bromide, Trimethylvinrylammonium Bromide, Valethamate Bromide. [0035] [0039] Iodide: [0036] [0040] Acetylcholine Iodide, Acetylthiocholine Iodide, Benzoyl- choline Iodide, Benzoylthiocholine Iodide, Benzyltriethylammonium Iodide, n- Butyrylcholine Iodide, n-Butyrylthiocholine Iodide, Decamethonium Iodide, N,N-Dimethylmethyleneammonium Iodide, Ethyltrimethylammonium Iodide, Ethyltri-n-propylammonium Iodide, (Ferrocenylmethyl)trimethylammonium Iodide, (2-Hydroxyethyl)triethylammonium Iodide, [bgr]-Methylcholine Iodide, O-[bgr]-Naphthyloxycarbonylcholine Iodide, Phenyltriethylammonium Iodide, Phenyltrimethylammonium Iodide, Tetra-n-amylammonium Iodide, Tetra-n- butylammonium Iodide, Tetraethylammonium Iodide, Tetra-n- heptylammonium Iodide, Tetra-n-hexylammonium Iodide, Tetramethylam- monium Iodide, Tetra-n-octylammonium Iodide, Tetra-n-propylammonium Iodide, 3-(Trifluoromethyl)phenyltrimethylammonium Iodide. [0037] [0041 ] Hydroxide: [0038] [0042] Benzyltriethylammonium Hydroxide, Benzyltrimethyl- ammonium Hydroxide, Choline, n-Hexadecyltrimethylammonium Hydroxide, Phenyltrimethylammonium Hydroxide, Sphingomyelin, Tetra-n- butylammonium Hydroxide, Tetra-n-decylammonium Hydroxide, Tetraethylammonium Hydroxide, Tetra-n-hexylammonium Hydroxide, Tetramethylam- monium Hydroxide, Tetra-n-octylammonium Hydroxide, Tetra-n- propylammonium Hydroxide, 3-(Trifluoromethyl)phenyltrimethylammonium Hydroxide.

0018[0039] [0043] Others:

0019[0040] [0044] Acetylcholine Perchlorate, Benzyltriethylammonium Di- chloroiodate, Benzyltrimethylammonium Tetrachloroiodate, Benzyltrimethyl- ammonium Tribromnide, Betaine, Betaine Hydrochloride, Bis(tetra-n- butylammonium) Dichromate, Bis(tetra-n-butylammonium) Tetracyanodi- phenoquinodimethanide, L-Carnitine, 3-[(3-

0020Cholamidopropyl)dimethylammonio]-1 -propanesulfonate, Denatonium Ben- zoate, n-Dodecyldimethyl(3-sulfopropyl)ammonium Hydroxide, Inner Salt, N- Fluoro-N'-(chloromethyl)triethylenediamine Bis(tetrafluoroborate), n- Hexadecyltrimethylammonium Hexafluorophosphate, n- Hexadecyltrimethylammonium Perchlorate, n-Hexadecyltrimethylammonium Tetrafluoroborate, (Methoxycarbonylsulfamoyl)triethylarunonium Hydroxide, Inner Salt, Neostigmine Methyl Sulfate, n-Octadecyldimethyl(3- sulfopropyl)ammonium Hydroxide, Inner Salt, Phenyltrimethylammonium Tribrornide, Propionylcholine p-Toluenesulfonate, Tetra-n-butylammonium Azide, Tetra-n-butylammonium Bifluoride, Tetra-n-butylammonium Boro- hydride, Tetra-n-butylammonium Bromodiiodide, Tetra-n-butylammonium Dibromoaurate, Tetra-n-butylammonium Dibromochloride, Tetra-n- butylammonium Dibromoiodide, Tetra-n-butylammonium Dichloroaurate, Tetra-n-butylammonium Dichlorobromide, Tetra-n-butylammonium Difluoro- triphenylsilicate, Tetra-n-butylammonium Difluorotriphenylstannate, Tetra-n- butylammonium Dihydrogentrifluoride, Tetra-n-butylammonium Diiodoaurate, Tetra-n-butylammonium Hexafluorophosphate, Tetra-n-butylammonium Hy- drogensulfate [for Ion-Pair Chromatography], Tetra-n-butylammonium Hy- drogensulfate, Tetra-n-butylammonium Perchlorate, Tetra-n-butylammonium Perrhenate, Tetra-n-butylammonium Phosphate, Tetra-n-butylammonium Salicylate, Tetra-n-butylammonium Tetrafluoroborate, Tetra-n- butylammonium Tetraphenylborate, Tetra-n-butylammonium Thiocyanate, Tetra-n-butylammonium Tribromide, Tetra-n-butylammonium Triiodide, Tet- raethylammonium Borohydride, Tetraethylammonium Perchlorate, Tetra- ethylammonium Tetrafluoroborate, Tetraethylammonium p- Toluenesulfonate, Tetraethylammonium Trifluoromethanesulfonate, Tetramethylammonium Acetate, Tetramethylammonium Borohydride, Tetramethylammonium Hexafluorophosphate, Tetramethylammonium Hy- drogensulfate, Tetramethylammonium Perchlorate, Tetramethylammonium Sulfate, Tetramethylammonium Tetrafluoroborate, Tetramethylammonium p- Toluenesulfonate, Tetramethylammonium Triacetoxyborohydride, Tetra-n- propylammonium Perruthenate, Trifluoromethanesulfonic Acid Tetra-n- butylammonium Salt.

0021[0041] The antimicrobial agent can be disposed in the polymeric material forming the insert body, or into a first polymeric material where the insert body is constructed of a plurality of polymeric materials or parts.

0022[0042] Generally, the concentration of the antimicrobial agent can be as little as about 500 ppm, with the critical parameter being antimicrobial efficacy against the target microbe(s). [0043] Preferably, the insert device is manufactured with a high antim- icrobial agent concentration therein. Upper limits on the concentration of antimicrobial agent may be imposed by the polymer (e.g. extreme concentrations of agent may disrupt the polymerization or post-polymerized structural integrity of the insert body), cost, appearance, or other factors known to those of skill in the art. In trials, insert devices having 40% antimicrobial agent by weight of polymeric material have proven efficacious and structural sound.

0023[0044] Most preferably, the antimicrobial agent used exhibits a migratory property within the matrix of the polymeric material. Preferred antimicrobial agents include those that exhibit a substantially controlled migration through the polymeric resin from which a frame element has been manufactured to the exposed surface of the frame element until a point of equilibrium is reached. [0045] Abrasion of the material surface during use or degradation of the exposed antimicrobial agent removes these antimicrobial agents and disrupts the established equilibrium. This stimulates additional migration of agent to the surface until a new equilibrium is reached. [0046] Several of the above mentioned antimicrobial agents exhibit this type of migration. Specific organic antimicrobial agents having this ability in- elude 5-chloro-2-(2,4-dichlorophenoxy)phenol; tolyl diiodomethyl sulfone; zinc pyrithione; sodium pyrithione; ortho phenylphenol; sodium ortho phenyl- phenol; iodo-2-propynyl butylcarbamate; poly[oxyethylene(dimethyliminio) ethylene(dimethyliminio)ethylene chloride]; propiconazole; tebuconazole; bethoxazin; thiabendazole; polyhexamethylene biguanide (i.e., PHMB); 1 ,3,5-triazine-1 ,3,5-(2H,4H,6H)-triethanol commercially available under the tradename Onyxide; and isothiazalinones such as N-butyl-1 ,2- Benzisothiazonlin-3-one, 4,5-dichloro-2-n-octyl-4-isothiazolin-3-one, 2-n- Octyl-4-isothiazolin-3-one, 2-Methyl-4-isothiazolin-3-one, 5-Chloro-2-methyl- 4-isothiazolin-3-one. [0047]

0024[0048] An insert device as described herein can be constructed in any of a variety of geometric shapes. Prototype insert devices have been made in three-dimensional rectangular shape, disc shape, twin-disc shape, and a toroid shape. Other shapes can be employed as desired or as need to suit the space into which the insert device is intended to be placed. [0049] Generally speaking, the chosen shape will facilitate fitment of the insert device into a desired space and, preferably, optimize the surface area of the insert device presented to stagnant liquid. In most cases, it is ex- pected that surface area should be maximized. However, it is acknowledged that gross surface area may be of lesser importance where the antimicrobial agent(s) used are especially efficacious and/or the target microbes readily susceptible to such antimicrobial agent(s). [0050] In use, the antimicrobial device is disposed within a water- retaining location of the appliance such that it can reach the areas of water stagnation and/or microbial colonization; that is, in, on, or near a wettable surface of structural element of the appliance. The structural device is expected to, but not necessarily required to, comprise an inner surface of the appliance. [0051] The liquid flowing through the appliance generally is a rinsing liquid used to wash dirt off the articles placed inside the appliance. The rinsing liquid can be water, water mixed with a rinsing agent, a rinse aid, a salt or the like, as well as other useful liquids for washing processes. [0052] Suitable locations within the appliance for placement of the antimicrobial device include: at the base of a dish or cutlery basket; in a drain pan, catch pan or catch tray (such as found under refrigerator ice/water dispensing elements); within a sump housing or other sump component; and within a pipe or tubing for water, washing fluid and the like.

0025[0053] After typical use of the appliance, stagnant liquid is incompletely removes from and collects, e.g., in the sump, outlet, and/or pipes of the appliance, where rinse liquid held, routed, and/or flowed. The antimicrobial device disposed in this area of the appliance contacts residual liquid and can advantageously prevent the growth or spread of microorganisms.

0026[0054] It will be appreciated that an antimicrobial structural element can be replaced if desired (e.g., if damaged) with another antimicrobial structural element, without resulting in loss by the appliance of its antimicrobial property.