2. The State of the Art.

Antimicrobial compounds have been used for decades in health care environments, such as in hospitals and physicians'offices, ever since Louis Pasteur's discovery of microbes as communicators of disease and infection. In the typical health care setting, different types of compounds are used to clean and disinfect different surfaces. These compounds can be as varied as the surfaces; everything from floors to tables to countertops made from plastics (e. g., melamine types) or metals (e. g., stainless steel) need to be cleaned.

More recently, antimicrobial compounds have been sold to consumers especially for cleaning bathroom fixtures (e. g., toilets, sinks, bathtubs and showers). These compounds are typically a quaternary ammonium compound optionally mixed with a surfactant, detergent, foaming agent, mild abrasive, and the like, and various combinations thereof. Still more recently, the transmission of infections microbes from raw food products, typically raw proteinaceous foodstuffs (typically chicken and beef), has heightened consumer awareness of microbial contamination and the need to cleanse and disinfect food preparation utensils and surfaces. Accordingly, the latest products have been liquid soaps containing an antimicrobial compound; these types of products were formerly available only in hospitals where soaps and

surgical gowns had antibacterials incorporated therein. And still more recently childrens'toys, pacifiers, and various apparatus (e. g., playpens, bassinets, etc.) have been available with antibacterial properties so that microorganisms do not grow thereon. See, e. g., Stuart H. Levy,"The Challenge of Antibiotic Resistance,"Scientific American (March 1998, p. 46-53).

Concomitant with consumer's awareness of becoming accidentally contaminated from bacteria living on food preparation surfaces, manufacturers and consumers came to realize that items such as sponges and towels (paper or cloth) that are used to clean such surfaces could be microbe-friendly environments because of their relatively high residual water content after use.

Besides a food source and a tolerable temperature range, the other main requirement for bacterial growth is water. Sponges and towels absorb water and even when wrung and squeezed, with retain a sufficient amount of water to allow for bacterial growth in their interiors. For example, Roenigk, in U. S.

5,541,233 (the disclosure of which is incorporated herein by reference) describes the use of the combination of a chelating polymer and a metal complex used in a water absorbing porous article (such as a sponge or towel).

Summary and Objects of the Invention Among various objects of this invention are providing a new, durable, non-absorbent, scrubbing article in which the growth of microbes is deterred; the new scrubbing article is preferably abrasive, and is preferably provided as a flexible nonwoven pad.

In one embodiment, this invention provides a scrubbing pad comprising a nonwoven pad in which the fibers of which the pad is comprised have a coating comprising an antimicrobial compound. The antimicrobial compound is preferably dispersed in a liquid material that is coated onto the fibers and then cured. The antimicrobial compound is thus locked into the nonwoven

pad and does not leach out to the surface being cleaned. The liquid material preferably has admixed therein an abrasive for the production of an abrasive, antimicrobial scrubbing article.

Detailed Description of Specific Embodiments Nonwoven pads and similar articles are per se well-known and will not be discussed herein in detail. In general, the nonwoven articles of this invention are preferably made from a durable, synthetic fiber such as a polyamide, a polyester, or a tough polyolefin; exemplary preferable fibers are comprised of nylon 6/6, poly (ethylene terephthalate), or polypropylene. The raw material fibers preferably have a denier in the range of 6-200 dpf, with 15 i 2 dpf most preferred. The fibers are preferably provided from the manufacturer as staple fibers, preferably of 1.5" 0. 5" lengths, already crimped (5-15 crimps/inch). The fibers should have a tenacity sufficient for domestic scrubbing applications; a fiber having a tenacity of at least about 2.5 gpd and an elongation of 100-175% is suitable for practicing this invention. The fibers provided by the manufacturer typically are providing having an antistatic finish thereon.

The fibers are typically provided by the manufacturer (e. g., DuPont, Wellman) as a bale, which is opened with a conventional device that gently opens the bale and separates the fibers from each other (e. g., similar to a carding device). The fibers are then formed into a thin web using a conventional device (e. g., a garnet). The thin web is then operated upon by a conventional cross-lapping device. Following this, the web is fed into a Rando Web device, which randomly redistributes the fibers in the web. The integrity of the web is then increased by an operation such as needlepunching. The result of this processing is a nonwoven article having a thickness of about 9.5 mm zt 3 mm (3/8"=1 1/8") and a base weight of about 4 oz./yd. 2 (about 136 g/m2).

The fibers of the nonwoven article are then permanently coated with an antimicrobial compound. Preferably, the antimicrobial compound is dispersed in a curable liquid that is coated onto the fibers of the nonwoven and then cured. Of course, the fibers could be coated prior to formation of the web if an abrasive (as described later) is not present in the coating formulation (because the abrasive fibers would likely cause significant wearing of the fiber handling equipment). Suitable antimicrobial compounds should have limited solubility in water so that they do not leach from the coating in use (or afterwards while the pad is still wet), they should have a low toxicity in the event they do leach out (and for safety of the workers making the product), and should be hypoallergenic to the extent possible (e. g., non-dermally irritating). Exemplary antimicrobials are iodosulfones such as diidomethyl p-tolyl sulfone (CAS Reg. No. 20018-09-1), diiodomethyl p-chlorophenyl sulfone (CAS Reg. No. 20018-12-6), and the like, and mixtures thereof ; these sulfones are known by their respective trademarks of AMICAL 48 and AMICAL 77; AMICAL FLOWABLE (EPA Reg. No. 48301-24, from Angus Chem. Co.) is preferred. Antimicrobials are preferably chosen also for their specificity against certain bacteria known (and/or suspected) to cause food- borne illness.

The antimicrobial is coated onto the fibers of the nonwoven article preferably by being dispersed in a curable, film-formable vehicle or binder.

Suitable binders can be those typically used in nonwoven abrasives, such as phenol formaldehyde, acrylic latex, and styrene butadiene latex. These binders are typically provided by their manufacturers as aqueous liquids. The antimicrobial compound must be dispersible in the binder, either directly or with the aid of a compatible surfactant or coupling agent that does not degrade the antimicrobial properties of the biocide or interfere with coating the fibers or curing of the coating. Because these types of binders (aqueous-based, latexes) are typically provided as a liquid, the antimicrobial can be

compounded with the binder under low shear to form a liquid binder/antimicrobial mixture. Although any suitable method for mixing will likely function, it is preferred to mix under low shear (such as with a paddle mixer). The binder is preferably thermally-curable at a relatively low <BR> <BR> temperature, most preferably at a temperature in the range of 250° F. i 25° F.; the curing temperature must be below the temperature at which the antimicrobial degrades or decomposes. To facilitate curing at the relatively low temperature range indicated, a cross-linking agent is preferably added to the binder composition. Suitable cross-linking agents are various bifunctional and multifunctional aziridines such as described in U. S. Pats. Nos. 3,874,914, 4,278,578,4,031,053,4,605,698,5,300,325,5,164,467, and 5,545,713 (the disclosures of which are incorporated herein by reference). Additionally, the binder must have an affinity for the fibers of the nonwoven so that the binder in a liquid form will wet and coat (i. e., form a film on) the fibers and remain coated until curing is achieved. Further, the binder in a cured state should be sufficiently flexible, as is the pad, so that it does not crack or degrade during use.

The nonwoven article is coated with the binder/antimicrobial mixture.

Preferably the fibers of the nonwoven are coated by spraying the binder/- antimicrobial mixture onto the nonwoven until it is saturated; dipping in a bath can also be used. Thereafter, the binder is cured in an oven to form an antimicrobial coating on the fibers of the nonwoven. The coating and curing processes is repeated preferably about 4 times per article to produce a commercial product. The total amount of binder coated onto the fibers will be determined, to a significant extent, by the characteristics desired for the final product. In general, the more binder the higher the production and materials cost, the more efficient the antimicrobial properties (i. e., there are fewer uncoated areas of the nonwoven), and the more durable the product (i. e., the thicker the coating the more wear-resistant it is likely to be). The amount of

binder (with the admixed antimicrobial and other ingredients) coated and cured onto the nonwoven can be determined by weighing the nonwoven before and after coating and curing. As mentioned above, the preferred basis weight for the present nonwoven before being coated is about 4 oz./yd. 2.

After four rounds of coating and curing, the preferred basis weight is 8-60 oz./yd. 2, most preferably about 21 oz./yd..

After the coating is subjected to a final curing step, the nonwoven is stored in the configuration of a roll until such time as it is used to make a commercial product. At that time, the roll is unwound and cut into rectangular pads that are packaged and shipped to retail establishments for purchase and use by the consumer.

The binder preferably also has additional ingredients compounded therein along with the antimicrobial. One preferred ingredient is abrasive particles, especially alumina having a size distribution generally between -120 mesh and +240 mesh or finer (e. g., 65-110 um or finer). Alumina (aluminum oxide) is a preferred abrasive material because it is relatively inexpensive; other suitable abrasives include silicates such as silica (silicon oxide) and magnesium silicate, carbides such as silicon carbide and tungsten carbide, and any other conventional abrasive available in a particulate form that is suitable for the final application and can be dispersed in the liquid binder. (For example, a very hard abrasive would likely not be suitable for household use where soft plastic surfaces, such as FORMICA brand polymers (urea-formaldehyde and melamine), are the substrates to be cleaned and scrubbed, or anywhere the appearance of the substrate might be compromised by the use of too aggressive an abrasive.)

Other ingredients that can be compounded into the binder are colorants (e. g., dyes or pigments, such as phthalocyanine green), processing aids, flow control agents, antioxidants, and the like.

The benefits of the present invention are that the abrasive pad produced is resistant to the growth of bacteria even when residual water remains in the pad. As mentioned above, the presence of water is often sufficient to allow the growth of undesirable microbes. While this problem is more apparent with absorbent articles such as sponges and towels, the problem is generally unappreciated with nonabsorbent articles such as nonwoven scrubbing pads.

The present invention solves this problem by anchoring an antimicrobial agent in a binder that coats the fibers of the nonwoven.

The foregoing description is meant to be illustrative and not limiting.

Various changes, modifications, and additions may become apparent to the skilled artisan upon a perusal of this specification, and such are meant to be within the scope and spirit of the invention as defined by the claims.