WO2003043421A1

WO2003043421A1 - Composition for rendering surfaces microbial resistant

Info

Publication number: WO2003043421A1
Application number: PCT/US2002/037177
Authority: WO
Inventors: Mohan L. Sanduja; Carl Horowitz; Felicia Dragnea; Paul Thottathil
Original assignee: Sanduja Mohan L; Carl Horowitz; Felicia Dragnea; Paul Thottathil
Priority date: 2001-11-19
Filing date: 2002-11-19
Publication date: 2003-05-30
Also published as: AU2002352809A1; TW200301712A

Abstract

The invention provides a water-based composition for grafting an antimicrobial agent onto a substrate. The composition includes a salt of a polymerizable anionic monomer or prepolymer, a graft initiator, a catalyst, and an amount of an cationic antimicrobial agent sufficient to provide an effective concentration in a polymerized graft coating, that is dissolved or dispersed in a compatible water-based solvent system. Substrates treated with the composition and methods of treating substrates with the composition of the invention are also provided.

Description

COMPOSITION FOR RENDERING SURFACES MICROBIAL RESISTANT

FIELD OF THE INVENTION

This invention relates to compositions and methods for grafting various types of substrate materials with one or more agents selected to kill and/or inhibit microorganisms that come into contact with a treated surface.

BACKGROUND OF THE INVENTION

Antimicrobial coatings and additives are known and employed to treat objects and articles of manufacture for which such antimicrobial properties are desirable. Typically, these additives are formulated into a paint or similar coating composition, or mixed into a surface polymer coating so that the antimicrobial is released by diffusion from the treated surface or by erosion of the applied coating. There are a wide variety of substrates for which antimicrobial coatings would be desirable, particularly if new compositions and methods were available to allow for simple, economical and permanent treatment of substrates, during or after manufacture.

Substrates contemplated to be treated with compositions and methods of the invention are especially those that are prone to contamination with various kinds of microbes, and thus become hazardous when used in household and industrial applications. Such microbial contamination can result in product loss and cause potential sanitation, health and other problems, and, in turn, directly or indirectly, can result in increased costs of operation for many types of undertakings.

One way in which permanent treatment of substrates has been accomplished is by mixing an antimicrobial agent into a paint or polymer. For instance, U.S. Pat. No. 5,532,291 teaches resilient floor coatings that include antimicrobial agents dissolved in tributoxyethyl phosphate and applied as a conventional coating with a mixture of polymers. U.S. Pat. No. 5,993,840 teaches a non-woven material containing a mixture of polymeric biguanides for use, e.g., in disposable diapers which are only to be used once.

Another, more permanent way to affix desired materials to a substrate is by graft coating. Graft coating involves chemically activating the surface of a substrate to be treated, and then providing suitable reagents to covalently bond to the activated surface. U.S. Pat. Nos. 4,898,676 and 4,966,872, incorporated by reference herein in their entireties, both teach germicidal activated carbon filters graft coated with polymerized salts of anionic monomers polymerized with cationic germicides, e.g., germicidal quaternary ammonium compounds that are chemically grafted onto activated carbon as a permanent coating to protect activated charcoal water filters. However, these patents fail to provide for simple and economical graft coating compositions and methods to provide many other types of substrates with a broad spectrum antimicrobial graft coating.

While graft coating of a number of substrates with antimicrobial and other types of substances is generally known, there remains a longstanding need in the art for economical, effective and environmentally acceptable compositions and methods for grafting antimicrobial coatings, and particularly bacteriostatic coatings, onto a variety of types of substrates,

SUMMARY OF THE INVENTION

Thus, in a first embodiment, the invention provides a water-based composition for grafting an antimicrobial agent onto a substrate, also referred to herein as a grafting solution. The composition or grafting solution includes a salt of a polymerizable anionic monomer or prepolymer, a graft initiator, and an amount of an antimicrobial agent sufficient to provide an effective concentration in a polymerized graft coating, dissolved or dispersed in a compatible water-based solvent system. A catalyst or polymerization initiator is optionally included in the grafting solution, or mixed into a pre-prepared grafting solution before use.

The antimicrobial agent is preferably cationic when present in the water-based solvent system of the composition, but optionally the antimicrobial agent is not cationic, and is simply dissolved or dispersed into the grafting solution and the matrix of the film coating after curing. In a further option, the non-cationic antimicrobial agent is present in the grafting solution together with one or more cationic antimicrobial agents. Depending on the nature of the substrate and its function or purpose, the antimicrobial agent is selected to provide the graft coated substrate with antibacterial, antifungal, and/or antiviral properties, to either inhibit growth or to kill microbes that come into contact with a treated surface. Preferably, the antibacterial agent is present in a concentration selected to be effective in the intended purpose, e.g., ranging in concentration from about 0.1 to about 5%, by weight.

The water-based solvent system is compatible with the components dissolved or dispersed therein, and comprises water and water soluble or miscible solvents such as alcohols, ethers, esters, and mixtures thereof.. The bulk of the non-solvent components include anionic monomers or prepolymers. Preferably, the anionic monomer or prepolymer comprises a sulfonic or carboxyl functional group. More preferably, the anionic monomer or prepolymer is a vinyl monomer or prepolymer, an acrylic monomer or prepolymer, and/or combinations of these materials.

Methods of rendering at least one surface of a substrate resistant to microbial contamination are also part of the invention, by coating the substrate with the grafting solution, as described supra, and then allowing the coating to cure.

A method of grafting antimicrobial agent onto a substrate having at least one surface, is also provided. The method includes the steps of coating a surface of the substrate with the grafting composition of claim 1, and allowing the coating to cure.

Graft coated substrates with antimicrobial coatings are also provided, e.g., which includes substrate comprising a polymer coating covalently grafted to a surface of the substrate. The polymer coating includes at least one antimicrobial agent in a concentration effective to inhibit growth of bacteria or fungi thereon. The antimicrobial agent is 2,4,4'- trichloro 2'-hybroxy-diphenyl-ether, diiodomethyl p-tolyl sulfone, and/or combinations thereof, and the polymer coating includes from about 50% to about 80%, by weight, of an acrylic polymer or copolymers thereof.

DETAILED DESCRIPTION

Accordingly, the invention provides compositions and methods for covalently and permanently grafting one or more antimicrobial agents onto a substrate.

Such grafting involves the "activation" of a substrate to convert some part of the substrate surface into moieties able to covalently bond to one or more supplied monomer, prepolymer or polymer reagents placed in contact with the substrate surface. Activation requires a graft initiator and/or activator, which typically removes hydrogens linked to surface functional groups, producing active moieties ready to covalently bond to a provided reagent. Hydrogen moieties are found, e.g., in most organic materials. For grafting coatings onto metals or other non-organic materials, hydroxyl moieties present as part of trace surface oxidation are thought to be provide a site for surface activation of such non-organic substrates.

Graft coatings according to the invention optionally also provide treated substrates with a variety of additional desirable properties, in addition to antimicrobial properties. Simply by way of example, these additional properties decorative colors, markings or mdicia, waterproofing, resistance to abrasion, and so forth. In brief, the grafted coating is produced by applying a composition that includes suitable monomers, prepolymers, a graft-initiator, a polymerization initiator or catalyst, one or more selected antimicrobial agents, and other more conventional additives for appearance and long term stability. Preferably, the monomers or prepolymers are anionic in nature, and the antimicrobial agent or agents are cationic in nature.

In order to better appreciate the scope of the invention, the following terms are defined. "Microbes," according to the invention, are e.g., bacteria, fungi, viruses and related microorganisms. For economy of description, reference to "fungi" herein includes yeasts and molds, unless otherwise indicated. Further, unless otherwise indicated, the term "antimicrobial" refers broadly to both microbicidal and microbistatic agents, h certain optional embodiments, the scope of the invention is also contemplated to include antiviral agents, i.e., agents that kill, inactivate, or otherwise render viruses substantially less infective, on treated surfaces.

In certain embodiments, one or more of the included antimicrobial agent(s) are microbicidal, i.e., will kill microbes, e.g., bacterial, fungi, and/or other such microorganisms.

In a preferred embodiment, one or more of the included antimicrobial agent(s) are bacteriostatic, i.e., will act primarily act by inhibiting growth or replication of bacteria, or otherwise render bacteria contacting a treated surface substantially less infective. In other preferred embodiments, the antimicrobial agent is a fungistatic agent that primarily acts by inhibiting growth or replication of molds and yeasts.

Percentages of components of the inventive grafting solution that are stated to be "by weight," are calculated relative to the total weight of the prepared solution or formulation, unless otherwise specified.

For purposes of the present invention, the use of the singular or plural is not meant to be limiting of the numerical number of the referenced item or object. Thus, the use of the singular to refer to an object, agent, or the like, does not imply that only one object is treated, and/or only one agent is employed, and the use of the plural does not exclude application to a single referenced item, unless expressly stated. The terms, "agent," "reagent," "component," and the like, may be used interchangeably with reference to materials used to prepare the inventive composition.

These and other features of the invention are described in further detail, below. Graft Coating Reaction

Without meaning to be bound by any theory or hypothesis as to any proposed mechanism underlying the grafting reaction of the inventive process, the grafting reaction is believed to take place by means of a chain polymerization mechanism. This type of polymerization reaction, also referred to in the art as a "backbiting" reaction, consists of initiation and propagation reactions. Essentially, a graft initiator is contacted with the surface to be treated, e.g., a surface of an article formed in whole, or in part, of a metal to be graft coated.

Reaction Mechanism

As illustrated below at (A), the substrate, "S-H" is reacted with a graft initiator "GI" to form the activated substrate. At (B) an anionic monomer, exemplified by 2-acrylimido-2- methyl propane sulfonic acid is reacted with the surface and with an antimicrobial agent, in this instance the antibacterial compound 2,4,4 trichloro-2-hydroxydiphenyl ether.

rø + m → s+H+ (A)

This results in the structure illustrated by (C), providing an agent, e.g., a bacteriostatic and/or fungicidal agent, grafted to the substrate surface via the provided polymer linker.

1

Substrates and Graft Coated Articles

The term "substrate" as employed herein includes any object or article of manufacture that is graft coated with the compositions according to the invention. Preferred substrates include objects, articles of manufacture, compositions, and the like, composed of any material that it is desired to surface-modify to impart antimicrobial properties. In certain aspects of the invention, activated carbon is optionally excluded as a substrate.

Thus, broadly, substrates to be treated with the with the inventive graft coating composition include metal objects or articles of manufactures, including, for example, silver, brass, copper, stainless steel, electroplated metals such as chromed steel, etc. Additional substrates to be treated include organic compositions such as wood, e.g., raw or painted wood and wood products, e.g., plywood, wood-related compositions including particle board, cardboard, and paper. In particular, substrates to be treated include household and industrial articles of manufacture and surfaces, such as kitchen surfaces, e.g., sink, counter and refrigerator surfaces, as well as bathroom surfaces, e.g., toilet seats, bath and shower surfaces, etc.

General household or institutional furnishings are also contemplated to be treated with the inventive graft coating composition, including substrates associated with heating and air-conditioning equipment, e.g., the insides of vents, airducts, dampers, heat exchangers, condensate collection systems, and the like.

General household or institutional furnishings include those with surfaces generally employed in, e.g., kitchens and bathrooms, including, but not limited to, metals, as well natural and synthetic tile materials, marble, granite, plastics, plastic laminates, e.g., Formica™ and Corian™ surfaces, and their respective laminate and composite generic counterparts.

In yet another aspect of the invention, substrates to be treated with the inventive compositions include, e.g., rubber and other pliable polymers, e.g., employed for medical or food handling purposes as tubing, gloves, and the like, as well as fabrics, including bandages, wound dressings, suture thread, and other medical implements. Such substrates are also contemplated to include diaper linings, and the like.

In yet a further aspect of the invention, substrates to be treated with the inventive compositions include, e.g., natural and synthetic fabrics for use in air filters, e.g., fiber or polymer-type air filters, clothing, linens, e.g., towels, sheets, and pillow cases, paper for tissues, paper plates, paper towels, and the like.

In a still further embodiment of the invention, substrates to be treated with the inventive compositions include, e.g., natural organic materials such as food and living tissue, e.g., for food preservation and/or preventing wound infection, transmission of skin diseases or disorders, and so forth. Thus, in a somewhat related embodiment, the substrate to be treated includes keratinous materials generally, including skin, hair, nails, and so forth to provide antimicrobial treatment, for such tissues.

Therefore, the invention relates to the treatment of different substrate materials with a grafting solution or composition that contains one or more antimicrobial agents, that are grafted or covalently bonded to the surface of any treated substrate.

Grafting Solution or Composition

The grafting solution preferably includes a salt of a polymerizable anionic monomer that is linked to a cationic antimicrobial agent, as described above. The resulting grafting solution, when applied onto various substrate materials imparts the antimicrobial properties of the included germicide(s) to the grafted surface

Preferably, the included anionic monomers are those which contain either sulfonic (-SO₃H) or carboxyl (-COOH) groups, and are preferably those of the vinyl or acrylic type. Among these suitable monomers are ethyleneimine, hydroxyethyl methacrylate, dimethylaminoethyl methacrylate, ethylacrylate, butylacrylate, as well as carboxylated and sulfonated vinyls such as vinylchloride, vinylpyrolidine, vinylidene chloride, vinylidene bromide, etc.

Preparation of Grafting Solution

The grafting solution is prepared in a water-based solvent, or water-based solvent system, compatible with the reagents selected for grafting. Water-based solvents are selected depending on the prepolymer and/or monomer employed, and can optionally include, in addition to water, compatible polar solvents such as water soluble or water miscible alcohols, ethers, esters and derivatives and mixtures thereof, and other readily available water soluble or dispersible solvents. Preferably, the reagents form a solution, suspension and/or dispersion when combined in the water-based solvent or solvent system.

Preferred ethers include, for example, propylene glycol methyl ether. Propylene glycol methyl ether is added, for example, in a concentration ranging from about 1 to about 20%), by weight.

Alcohols include, e.g., C₂-C₅ or greater, alcohols, including ethanol and/or isopropanol. Preferably, alcohols are added in a concentration ranging from about 0.3 to about 10%», by weight. More preferably, the alcohols are added in a concentration ranging from about 0.5 to about 6%>, by weight, relative to total solution weight.

In certain embodiments, alkaline reagents such as ammonium hydroxide are added as required, e.g., to enhance solubility and promote cation formation for antimicrobial agents that may be relatively nonionic at neutral pH, e.g., triclosan. Graft initiators ("GI") are preferably metal ions including, for example, iron, silver, cobalt, copper, cerium, and/or combinations thereof, or any other art-known graft initiator. The graft initiators are preferably employed in a concentration ranging from about 0.01 to about 1.0%, and more preferably in a concentration ranging from about 0.001 to about 0J % by weight, relative to the weight of prepolymer or monomer(s) present. More preferably, as exemplified herein, ferrous ion is employed in a concentration ranging from about 0.0001 to about 0.0004 %> by weight, relative to the total solution weight.

Catalysts (also art-known as polymerization initiators) are preferably peroxides ("ROOH"), wherein R is H or any organic moiety compatible with the desired grafting reaction. Preferred peroxide catalysts include, for example, hydrogen peroxide and any organic peroxide, such as, e_^g., benzoyl peroxide, methyl ethyl ketone peroxide, 1 -butyl hydroperoxide and derivatives and combinations thereof. The peroxide catalysts are preferably employed in a concentration ranging from about 0J to about 5%>, or greater. More preferably, the peroxide catalysts are employed in a concentration ranging from about 0.05 to about 1.0%. Hydrogen peroxide is preferably employed in concentrations ranging from about 0.0001 to about 0.0005%, or more, by weight.

Preferably acrylic monomers or prepolymers are employed. These will have the desirable properties of, include, for example, forming hard and water resistant coatings, which can be left clear or pigmented as desired, which will not interfere with the action of the grafted agent. More preferred are aqueous colloidal acrylic dispersions that provide acrylic prepolymers. These are commercially available, e.g., from NeoResins (Wilmington, Massachusetts; formerly known as Zeneca Resins) under the tradename of NeoCryl^®. In particular, NeoCryl^® 250, NeoCryl^® BT-520, NeoCryl^® BT-640 are especially preferred. These are employed, for example, in a concentration ranging from about 50% to about 80%, by weight of the graft coating formulation.

Acrylic monomers are also optionally employed, and include, simply by way of example, acrylamido derivatives, such as acrylamido-2-methylpropanesulfonic acid sodium salt, marketed under the tradename AMPS™ by Lubrizol Process Chemicals (Wicklittle, Ohio). Especially preferred is AMPS™ 2403 monomer, marketed as a 50%) aqueous solution employed, e.g., in a concentration ranging from about 0.03%> to about 010%>, or more, by weight.

In another preferred embodiment, suitable inorganic or organic dyes or pigments that impart a marking color are mixed into the grafting solution or covalently linked by art- known methods to one or more of the components of the liquid composition. These include colorants that impart red, green, orange, yellow, blue, violet and variations of these. Suitable colorants for this purpose include, simply by way of example, Tint Ayd WB™ colorant(s) commercially available, for example, from Daniel Products (Jersey City, New Jersey).

Additional such pigments or colorants include, e.g., , zirconium oxide, zircon, zinc oxide, iron oxide, antimony oxide, and particularly weather resistant coated types of TiO₂. The pigments may also be blended with a suitable extender material which does not contribute significantly to hiding power. Suitable extenders include silica, baryte, calcium sulfate, magnesium silicate (talc), aluminum oxide, aluminum silicate, calcium silicate, calcium carbonate (mica), potassium aluminum silicate and other clays or clay-like materials. Where present, the pigments and extenders are normally present at a level of from about 1 to about 10 parts by weight per part by weight of the polymer components of the grafting composition, on a dry weight basis.

Further optional components of the liquid composition of the grafting solution and of the formed graft coating include, for example, anti-oxidants, UN. absorbing compounds, art known defoamers, e.g., Νalco Νos. 2300, 2309 and/or 2343, as supplied by Νalco Chemical (Νaperville, Illinois) employed according to the manufacturer's guidelines. Polymer stabilizers that are well known to the art, are also optionally employed in art-known proportions. The coating composition of the invention may also optionally include other ingredients in amounts which are commonly included in paint and lacquer formulations such, wetting agents, surfactants, emulsifiers, suspending agents, flow control agents such as waxes or wax dispersions, level agents, thickening agents, pH control agents, slip agents such as silica or clay and the like.

Prepolymers and/or monomers are preferably employed in the grafting solution in a concentration ranging from about 0.1 to about 80%>, by weight. In one optional embodiment, prepolymers and/or monomers are employed in a concentration 0.1 to about 50%>, by weight. In a further optional embodiment, the prepolymers and/or monomers are employed in a concentration ranging from about 0.1 to about 20%>, by weight, relative to the solution.

The pH of the formulated liquid composition is generally in the range of from about 6-8, and appropriate amounts of a suitable acid, e_^ . phosphoric or acetic acids or a base, e.g. sodium hydroxide, ammonia or ammonium hydroxide, may be included into the composition to adjust the pH as necessary. In certain preferred embodiments, the pH is greater than 8, e.g., ranging from pH 8 to pH 9, or higher. These alkaline pH ranges are optionally employed to enhance cationic species of otherwise nonionic antimicrobial agents, where otherwise compatible with the inventive graft coating solution.

Antimicrobial Agents

The above-described polymerizable monomer and/or prepolymer, is combined with one or more compatible antimicrobial agents, along with a compatible catalyst and a compatible graft initiator. Suitable antimicrobial agents are well known to the art and are preferably cationic in nature when incorporated into the graft coating solution. For example, quaternary ammonium compounds are art-known cationic antimicrobial compounds, however, in certain optional embodiments, quaternary ammonium compounds are not employed.

In other preferred embodiments, the grafting solution includes effective amounts of antimicrobial agents that are antimicrobial bisphenol compounds. Preferred antimicrobial bisphenol compounds include the halogenated diphenyl ethers. Halogenated diphenyl ethers represent a class of compounds that are well known to the art, starting with, e.g., U.K. patent No. GB 1038185, published in 1966, incorporated by reference herein in its entirety.

Even more preferred are chlorinated diphenyl ethers, and most preferred is triclosan (2,4,4'-trichloro 2'-hybroxy-diphenyl-ether; Cas No. 2280-34-5) a commercially available agent that is sold as Irgaguard^® B1000 from Ciba Specialty Chemicals Corp. (High Point, North Carolina). Triclosan is a bisphenol derivative that has bacteriostatic activity against a wide range of gram positive and gram negative bacteria. Triclosan is also reported to be active against fungi and yeasts. Triclosan is sparingly soluble in water and optionally solubility is enhanced in alkaline aqueous solution. Triclosan is preferably employed in a range of concentrations as recommended by the manufacture. More preferably, triclosan is employed in a concentration ranging from about 0J to about 5%> by weight of the grafting solution, and even more preferably in a concentration ranging from about 0J to about 2%>, by weight of the final, polymerized product.

It should be noted that the art generally considers many bisphenol compounds, and particularly triclosan, to be a nonionic compound. Without meaning to be bound by any theory or hypothesis as to a reaction mechanism, it is believed that triclosan and other nonionic bisphenols become sufficiently ionic in nature when present in a water-based solution, at an alkaline pH above the pKa of a given compound. Thus, graft coating formulations including triclosan are preferably prepared to have an alkaline pH, providing an effective concentration of cationic triclosan in the solution. In yet further preferred embodiments, the graft coating formulations optionally include one or more art-known antifungal agents compatible with the formulations of the invention. The various art-known classes of antifungal materials and compounds are described, e.g., in U.S. Pat. Nos. 6,248,761 and 4,552,885, incorporated by reference herein in their entireties. Further, the detailed descriptions of both the 6,248,761 and 4,552,885 patents provide an exhaustive listing of specific antifungal agents, which are also incorporated by reference herein.

Most preferably, the antifungal agents include, e.g., the antifungal sulfone derivatives, such as diiodomethyl p-tolyl sulfone (CAS registry 20018-09-1), a commercially available compound that is sold as a fungicide under the tradename Amical¹⁸ by Angus Chemical Co. (Chicago, Illinois). Diiodomethyl p-tolyl sulfone is reported to release iodine, in situ, and is believed to also inhibit or kill a wide range of microorganisms in addition to fungi, depending upon the conditions and concentration, including bacteria and certain viruses. Amical^® flowable fungicide (EPA Reg. No. 48301-00024) is the commercial form that is preferably employed in preparing the inventive graft coating compositions.

Diiodomethyl p-tolyl sulfone is generally employed in a concentration range as recommended by the manufacturer. More preferably, diiodomethyl p-tolyl sulfone is employed in a concentration ranging from about 0J0 to about 2%> by weight of the grafting solution. Combinations of plural antimicrobial agents, e.g., combinations of bacteriostatic and antifungal agents are also contemplated.

The Grafting Solution and Process

Ingredients are mixed in a suitable proportion, stirred to a uniform solution, and the resulting grafting solution is applied to the substrate to be treated. The time necessary for the reaction to run to completion depends up the reaction temperature, the reagents employed and the desired properties of the graft coating after application and curing.

Preferably, the metal substrate to be coated is subjected to an optional pretreatment cleaning, to remove any contaminating dust, grease and oil, prior to application of the grafting solution.

The mixed grafting solution is applied to a substrate by any available art-known method, including, e.g.. brushing, spraying, dipping, spin coating, vapor deposition, and the like. The viscosity of the grafting solution is adjusted as needed, so that, for example, it is sufficiently viscous for application by dipping or brushing, without significant dripping or running of the applied solution, or sufficiently thin when optionally sprayed onto the surface to be treated.

Generally, the solution is air dried onto the substrate, and then cured by the application of heat for a time period ranging, e_^g., from about 30 seconds to about 4 hours, at a temperature ranging, e.g., from about 100 to about 150 degrees F. When heat curing is undesirable, the coated substrate can optionally be allowed to cure at ambient temperature, e.g.. 25-30 degrees C, for a time ranging from about 30 seconds to about 6 or more days.

EXAMPLES

The following examples serve to provide further appreciation of the invention but are not meant in any way to restrict the effective scope of the invention.

EXAMPLE 1 Preparation of the Formulations

The ingredients of each composition, as described below in Tables 1, 2 and 3, were each taken into a container in the indicated proportions, and in the indicated order, and the contents were stirred to a uniform solution to prepare formulations for graft coating.

Table 1 ^!

Ingredients Parts Bv Wt wt %

DIW 105.00 \ 13.48

10% NH₄OH ! 97.50 ¹ 12.51

Acrylic prepolymer NeoCryl BT-520 ! 450.00 57.71

Propylene glycol methyl ether , 6.25 0.80

Ethanol 111.25 14.26

Irgaguard^® B1000 9.00 1.15

Monomer AMPS™ 2403 i 0.70 i 0.09

Ferrous ammonium sulfate (1%>) ! 0.001 ' 0.0001

Hydrogen peroxide 0.001 , 0.0001

- 779.702 1

-

^~ Table 2

Ingredients Parts Bv Wt wt %

DIW 74.50 16.34

Propylene glycol methyl ether ¹ 52.80 ! 11.58

Acrylic _prepolymer NeoCryl^® A-640 1 317.20 , 69.57

Isopropanol (IP A) ^l 2.50 ¹ 0.55

Amical^® Flowable (fungicide) 8.50 1.86

10% Nalco 2343 in IPA * 0.10 0.02

Monomer SR 9035™ * * , 0.30 , 0.06

Ferrous ammonium sulfate %) ' 0.001 J 0.0002

Flydr gen peroxide 1 o.ooi . 0.0002 ** SR 9035 Highly ethoxylated (15 mole EO) trimethylolpropane triacrylate supplied by Sartomer {Exton^ Pennsylvania) * Defoamer from Nalco Chemical (Naperville, Illinois).

Table -_ 3 _-

Ingredients I Parts Bv Wt wt %

DIW 11.70 ! 2.50

10% NH₄OH 1 74.50 i 15.94

NeoCryiJBT 520 ¹ 345.00 73.80

Propylene glycol methyl ether ¹ 4.80 1.02

Ethanol 24.00 ' 5.13

Amical^® Flowable (fungicide) 4.60 ' 0.98

Irgaguard^® B1000 _^ __ , 2.70 1 0.57

Monomer SR 9035™ 1 0.30 ! 0.064

Ferrous ammonium sulfate (1%) 0.001 ! 0.0002

Hydrogen peroxide 0.001 i 0.0002

EXAMPLE 2 Application of Mixed Solution to Substrates

The formulations of Tables 1, 2 and 3, as shown by Example 1, supra, were applied to a glass substrate by spraying. The coated substrate was then allowed to cure at room temperatures. Drying time ranged from 5.3 to 6.2 minutes. The film appearance was clear or mottled.

EXAMPLE 3 Confirming Properties of Coated Substrate

A. Mechanical Test

A coated substrate prepared by the methods of Examples land 2, is tested for mechanical adherence to the substrate surface by means of an art-standard tape pull test. Adhesive tape of a defined length and width is applied over a standard rectangle of substrate, and then sharply pulled away from the substrate. Substantially all of the grafted polymer coating remains affixed to the substrate surface, confirming the mechanical strength of the bonding by the coating to the substrate.

B. Test of Surface Bacteriostatic Properties

A coated substrate prepared with the formulation of Table 1 , by the methods of Examples 1 and 2, and is tested for bacteriostatic properties by demonstrating inhibition of the growth of Esherichia coli in culture. The test is conducted by any art standard method. For example, the test is conducted by inoculating suitable, commercially available, pre-prepared sugar-agar sterile Petri dishes, with a commercially available strain of Esherichia coli. The nutrient content of the Petri dishes is selected to be compatible with the culture requirements of the selected strain of Esherichia coli. The inoculation is made by brushing a sample of a densely grown Esherichia coli seed culture medium across the agar surface of each Petri dish, so that a uniform lawn of colonies grow up after incubation. Rectangles of glass, 1 cm square, are graft coated as above, on one side, with, and without (control) the Irgaguard B1000 component. Control glass squares are marked as such with a diamond stylus.

Graft coated glass is placed, coated side down, onto 24 Petri dishes as described above. Four Irgaguard B1000 grafted glass squares, and 4 control glass squares, are placed coated side down lightly onto the surface of each culture dish. Each prepared Petri dish is recovered and placed into an incubator at 37 degrees C. After 48 hours, the dishes are removed and scored for the presence of Esherichia coli seed colonies under each glass square. The results confirm a substantial degree of inhibition of Esherichia coli growth is provided by graft coating with the formula of Table 1.

The above tests are repeated for the formulas of Tables 2 and 3 (with Amical^®), using a commercially available strain of Saccharomyces cerivisiae in place of Esherichia coli, with compatible Petri dish culture medium, with similar results.

Claims

WHAT IS CLAIMED IS:

1. A water-based composition for grafting an antimicrobial agent onto a substrate, the composition comprising a salt of a polymerizable anionic monomer or prepolymer, a graft initiator, and an amount of an antimicrobial agent sufficient to provide an effective concentration in a polymerized graft coating, dissolved or dispersed in a compatible water- based solvent system.

2. The composition of claim 1 further comprising a catalyst.

3. The composition of claim 1 wherein the antimicrobial agent is cationic when present in the water-based solvent system composition.

4. The composition of claim 1 wherein the water-based solvent system is compatible with the composition and comprises water and water soluble or miscible solvents selected from the group consisting of alcohols, ethers, esters, and mixtures thereof.

5. The composition of claim 1 wherein the polymerizable anionic monomer or prepolymer comprises a sulfonic or carboxyl functional group.

6. The composition of claim 1 wherein the polymerizable anionic monomer or prepolymer is selected from the group consisting of a vinyl monomer or prepolymer, an acrylic monomer or prepolymer, and combinations thereof.

7. The composition of claim 3 wherein the acrylic monomer is an acrylamido derivative.

8. The composition of claim 3 wherein the acrylic prepolymer is an aqueous colloidal acrylic dispersion.

9. The composition of claim 1 wherein the antimicrobial agent imparts bacteriostatic properties to a graft coated substrate.

10. The composition of claim 1 wherein the antimicrobial agent imparts fungicidal properties to a graft coated substrate.

11. The composition of claim 1 wherein the antimicrobial agent is an antimicrobial bisphenol compound.

12. The composition of claim 1 wherein the antimicrobial agent is a halogenated diphenyl ether.

13. The composition of claim 1 comprising at least one additional antimicrobial agent.

14. The composition of claim 12 wherein the antimicrobial agent is selected from the group consisting of 2,4,4'-trichloro 2'-hybroxy-diphenyl-ether, diiodomethyl p-tolyl sulfone, and combinations thereof.

15. The composition of claim 1 wherein the antimicrobial agent is present in a concentration ranging from about 0J to about 5%, by weight.

16. A method of rendering at least one surface of a substrate resistant to microbial contamination, the method comprising coating the substrate with the composition of claim 1, and allowing the coating to cure, wherein the cured composition comprises an effective amount of the antibacterial agent.

17. The method of claim 16 wherein the substrate is an object or article of manufacture.

18. A method of rendering a substrate resistant to microbial contamination, the method comprising contacting the substrate with the composition of claim 1 and allowing the composition to cure, wherein the cured composition comprises an effective amount of the antibacterial agent.

19. The method of claim 18 wherein the substrate is selected from the group consisting of a foodstuff, a composition comprising keratin, and combinations thereof.

20. A method of grafting an antimicrobial agent onto a substrate having at least one surface, comprising coating a surface of the substrate with the composition of claim 1, and allowing the coating to cure.

2;1. A substrate with an antimicrobial agent covalently grafted thereto, prepared by the method of claim 16.

22. A substrate with an antimicrobial agent covalently grafted thereto, prepared by the method of claim 20.

23. A substrate comprising a polymer coating covalently grafted to a surface of the substrate, the polymer coating comprising at least one antimicrobial agent in a concentration effective to inhibit growth of bacteria or fungi thereon, wherein the antimicrobial agent is selected from the group consisting of 2,4,4'-trichloro 2'-hybroxy-diphenyl-ether, diiodomethyl p-tolyl sulfone, and combinations thereof, and the polymer coating comprises from about 50% to about 80%>, by weight of an acrylic polymer or copolymers thereof.