Residential areas are also affected and in particular, where dampness occurs or prevails, such as basement areas, porches and slab foundations. The method of the present invention involves the usage of a non-woven antimicrobial material, located between a floor covering, such as carpet, and the flooring and surrounding areas. The present invention also provides non-woven fabrics having antimicrobial properties.

BACKGROUND OF THE INVENTION Historically, antimicrobial carpets are known which are topically treated with minimal doses of antimicrobial agents. While these applications meet Government Standards for commercial carpets, namely Method GS-20, as the test for effectiveness, this test has inherent deficiencies. For one, by the nature of the test, minimal additions of antimicrobial agent have proven effective in the test; for another, the way the test is administered, topically treating the face fibers or the backing will pass the test and finally, the low dosage levels historically used in the industry have not translated in proven product performance to the end consumer and therefore, these have not been viewed as effective or as offering value added benefits. Another disadvantage with topical treatments other than the minimal amount of agent that is employed is that the agent is readily removed, particularly by cleaning operations. The latter often effect a trade-off, however, because the cleaning operation can employ antimicrobial agents whose residue is left on and in the carpet for subsequent

duty in killing the bacteria that is present. This too, can lead to erroneous evaluations of the initial treatment.

It is also known to employ antimicrobial agents within the fibers, from which various fabrics are woven, for a variety of end uses. One such technique is described in U. S. Pat. No. 3,959,556 which describes composite antimicrobial yarns comprising a mixture of natural and synthetic fibers, the latter having incorporated therein certain antimicrobial agents which are capable of migrating to the surface of the fiber and then transferring their antimicrobial properties to the natural fibers.

U. S. Pat. No. 4,401,712 discloses non-woven fabrics having antimicrobial properties. The invention is directed toward the addition of antimicrobial agents to the binding agent which is used to bind a web of textile fibers. The antimicrobial agent migrates to the surface of the binder and onto the fibers, continuously until the supply is exhausted. Such non-woven fabrics are useful in the manufacture of washing and wiping cloths, hospital gowns, sheets, pillow cases, and curtains, and as backing agents for garments, bed spreads and the like.

U. S. Pat. No. 4,769,268, relates to the stabilization of antimicrobial agents, thermoplastic compositions containing the same, and a method of melt processing such thermoplastic compositions. The patent discloses that it is known to form fibers from the thermoplastic compositions and to utilize the fibers to form articles such as carpets.

U. S. Pat. No. 4,343,853 discloses two-face fabrics containing antimicrobial agents and a method for imparting antimicrobial characteristics to two-face fabrics. The construction of the latter involves the formation of a face fabric, having no antimicrobial additives, and a backing fabric, having an antimicrobial additive incorporated therein. The patent discloses and claims such fabrics and a method of imparting antibacterial characteristics to untreated yarns in a two-face fabric. Typical examples include the construction of athletic sweatshirts and of carpets. The two fabrics are tied together in a conventional manner and one of the objects achieved is migration of the antimicrobial agent into the untreated, face fabric. The patent states that growth of mildew and other odor forming bacteria is significantly decreased by the invention, as

compared to other known approaches, where one face fabric is treated to protect against antimicrobial growth on the other.

While the art has dealt with the manufacture of fibers, fabrics and even carpet, having antimicrobial properties, it has not provided a method for controlling micro-organisms growing in, on and around floors and wall surfaces or for controlling mold, mildew and related odors. The method of the present invention can be practiced utilizing a non-woven antimicrobial fabric. Such fabrics and related articles are also novel.

SUMMARY OF INVENTION It is, therefore, an object of the present invention to provide a method for controlling biological attack from micro-organisms which come into contact with floors, floor coverings and wall surfaces.

It is another object of the present invention to provide a method, as above, which can control the growth of bacteria, mold, mildew and the generation of related odors in damp areas of residential, commercial and public buildings.

It is still another object of the present invention to provide a non- woven fabric, containing one or more antimicrobial agents, for use in conjunction with practice of the method of the present invention.

It is still a further object to provide a method for controlling biological attack from micro-organisms which come into contact with carpet or other floor coverings applied directly to concrete floor surfaces which inclues the addition of synthetic fibers, containing one or more antimicrobial agents, to the concrete.

At least one or more of the foregoing objects, together with the advantages thereof over the known art relating to methods for controlling the growth of micro-organisms in and around floor and wall surfaces, which shall become apparent from the specification which follows, are accomplished by the invention as hereinafter described and claimed.

In general, the present invention provides a method for controlling the growth of micro-organisms in conjunction with construction of buildings comprising applying a non-woven fabric containing at least one antimicrobial agent to floor or wall surfaces where micro-organisms can reside; applying a

covering thereover, the fabric forming a barrier between the surface and the covering, whereby passage of micro-organisms through the covering to the underlying surface is inhibited by the fabric.

The present invention also provides non-woven fabrics for controlling the growth of micro-organisms in buildings comprising from 50 to about 100 percent by weight of a synthetic fiber, containing at least one antimicrobial agent, in an amount of about 25 to about 50,000 parts by weight per million of the fiber and, from 0 to about 50 percent by weight of a synthetic fiber, devoid of antimicrobial agents, the non-woven fabric being employed to surfaces beneath subsequent covering materials.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view, partially broken away, depicting carpet applied over a non-woven antimicrobial barrier fabric, on a floor surface, according to the method of the present invention; Fig. 2 is a perspective view, partially broken away, depicting the use of the non-woven antimicrobial barrier fabric of the present invention, having been applied behind wallpaper; Fig. 3 is a perspective view, partially broken away, depicting the use of the non-woven antimicrobial barrier fabric of the present invention, having been applied behind tile; and Fig. 4 is a perspective view, partially broken away, depicting the use of the non-woven antimicrobial barrier fabric of the present invention, having been applied beneath stucco.

PREFERRED EMBODIMENT FOR CARRY) NU OUT THE INVENTION As noted hereinabove, the present invention is directed toward a method for controlling the growth and spread of micro-organisms, including but not limited to various strains of bacteria, fungi, algae and related living contaminants which spread and cause disease, as well as mold, mildew, related odors and occasionally, staining of affected areas and surrounding surfaces.

Thus, where dampness occurs, such as in basement areas, mold and mildew and the accompanying odor can be inhibited and virtually eliminated by treating the

affected areas according to the present invention. In addition to damp basement areas, it is desirable to control bacteria and other micro-organisms in hotels, hospitals, nursing homes, day care centers, recreational, exercise and health clubs, commercial kitchens, and the like.

In many of these environments, carpet is applied over floor surfaces, and occasionally some of the vertical wall surfaces, for reasons of aesthetics, sound barrier properties, comfort and safety, among others. Unfortunately, carpet can collect and house many micro-organisms, particularly due to sillage.

Moreover, because carpet is a covering, dampness and wetness are not readily removed. In the case of pillage, the base or backing of the carpet becomes a breeding area for the various micro-organisms which can cause and spread disease as well as mold, mildew and the like.

Once these liquids and accompanying micro-organisms pass through the carpet to the underlying support structure, it too can and does become infected. While carpet is typically applied to concrete floor surfaces in residential and commercial settings, the problem also exists over wooden flooring, various wall surfaces and virtually any surface onto which a covering can be applied. These surfaces inclue, without limitation, wallboard and floors behind and beneath tile; framework, sheathing, plywood and particle board used in construction behind stucco and other forms of exterior fascia; walls, behind wallpaper and other wall covering materials and substantially any other horizontal, vertical or sloping surfaces (roofs) where moisture can accumulate and/or bacteria, mold, fungus, mildew and the like can reside.

In its preferred embodiment, the method of this invention inclues the use of a non-woven fabric comprising synthetic fibers. The manufacture of non- woven fabric is well known and thus, does not require disclosure here. The preferred fabric comprises 50 percent by weight rayon and 50 percent by weight polypropylene. The polypropylene is, in turn, produced from antimicrobial fibers while the rayon is devoid of antimicrobial agents. Typically, the fabric has a weight of approximately 0.5 to about 50 ounces per square yard, with ranges of from about 0.5 to 15 ounces per square yard being preferred and ranges of from about 0.5 to 5 ounces per square yard being most preferred. It is also to be

appreciated that the non-woven fabric can comprise 100 percent by weight of a single fiber type, such as polypropylene.

Other useful synthetic fibers for practice of the present invention preferably include the polyolefins, such as polyethylene and polymethyl pentene; polyesters; nylon; acrylics; acetates; and polyvinyl chlorides and any other typical fiber-forming polymeric materials. Still other polymeric materials suitable, but less preferred, as fibers for the present invention include acrylonitrile-butadiene- styrene terpolymer (ABS), polysulphone, polybutylene terephthalate (PBT) and polyurethane.

Amorphous polyolefins such as polyethylene, polypropylene, and polymethyl pentene are generally most preferred because these fiber-forming polymers provide spaces or"zones"which are suitable for the deposition of antimicrobial agents within the fibers. Crystalline polymers such as nylon and polyester, while capable of being used to the purposes of the present invention, generally provide less suitable environments in which to place the antimicrobial agents. Any polymeric fibers which include sufficient space or large enough "zones"to deposit the antimicrobial agents without deleteriously altering the molecular structure or physical properties of the antimicrobial agents are desirable.

With respect to the preferred dimensions for the fibers, useful fiber lengths can range from about 0.04 to about 6 inches, with about 0.75 to about 3 inches being preferred and from about 0.9 to about 2.1 inches being most preferred. Useful fiber diameters can range from about 0.00011 to about 0.0038 inches, with about 0.0007 to about 0.0022 inches being preferred and from about 0.0007 to about 0.0014 inches being most preferred although broader ranges are not to be necessarily precluded. It is also customary to refer to the fiber yield, i. e., denier (determined by the weight in grams of a 9000 yard length), rather than diameter. Accordingly, useful deniers preferably range from about 0.04 to about 60 with about 2 to about 20 being preferred and from about 2 to 8 being most preferred.

Antimicrobial agents useful for practice of the present invention preferably are non-toxic and environmentally safe both during use and disposa.

Most antimicrobial agents control the growth of organisms by penetrating the

thin cell walls of the organism, thereby disrupting the metabolic function of the organism and ultimately killing the organism. However, non-toxic antimicrobial agents cannot successfully attack human and red-blooded animal cells, which have thick cell walls, thereby making these antimicrobial agents toxicologically safe in the dosage range indicated hereinbelow. Thus, it will be understood that the term"antimicrobial agents"includes any substance which effectively protects the fibers, the carpet, related adhesives for the application of carpet and, the surfaces to which the carpet is applied from biological attack from organisms including, but not necessarily limited to, fungi, bacteria, mold, mildew, algae, and other thin-celled organisms.

An example of an antimicrobial agent suitable for use in the present invention is a phenolic-based product with an extremely low toxicity level (LD50 of 3000-5000 mg/kg at 100%) currently available from Microban Products Company of Huntersville, North Carolina, under the tradename"Microban B".

"Microban"is believed to be a registered trademark owned by Microban Products Company for use in conjunction with liquid/spray disinfecting, antibacterial, antifungal and deodorizing preparations. The product is EPA registered-#42182-1. More specifically, Microban B is a polymer additive engineered to provide a controlled migration to the surface of the product in which it is incorporated, providing long-term efficacy, as detailed hereinbelow.

Dosage rates for the addition of antimicrobial agents to the fibers employed in the present invention vary significantly depending upon the strength required to inhibit targeted bacteria, fungi, mold, mildew and the like and can be coordinated with the amount of antimicrobial-containing fibers employed in the non-woven fabric. In most instances, the effective dosage will vary from about 25 parts per million to about 50,000 parts per million (ppm) by weight per weight of the fibers, with 250 to about 25,000 ppm being preferred and 400 to 20,000 ppm being most preferred, although lesser or additional quantities may be used to achieve suitable efficacy. A preferred amount is 5000 ppm of the foregoing antimicrobial agent in the polypropylene fiber. Nevertheless, it is to be understood that the selection of any specific amount will depend upon the antimicrobial objective to be achieved.

The preferred method of adding antimicrobials to the fibers is in the spinning, or extrusion, portion of the fiber-forming process. At this point, the antimicrobial materials are introduced while the fiber-forming polymers or materials are in the molten or liquid state, either from heat or chemical action.

As the fibers harden, the antimicrobial agents are seated into the amorphous zones of the fiber. Less preferred, but nevertheless suitable, is topical coating of antimicrobials onto the fiber surface. Thus, it will be understood that, for the purposes of this invention, when it is indicated that the fibers"include"an effective amount of at least one antimicrobial agent, it is meant that the antimicrobial agent may either be incorporated into or coated onto the fibers.

As noted hereinabove, when the antimicrobial agents are added to the fiber while the fiber is in its molten or liquid stage, the agent lodges in an amorphous, or clear zone within the fiber as it hardens. At this point, due to a process known as"solid state migration", the antimicrobial agent migrates to the surface of the fiber until equilibrium is reached in the internal vapor pressure of the polymer. When equilibrium is reached, the migration ceases and the antimicrobial agent is available to control organisms that contact it, or are in its zone of inhibition.

If the surface of the fiber is not abraded, then no addition migration occurs, providing long-ter inhibition capability. If abrasion occurs, the process repeats itself. Effective inhibition of organisms continues until all of the antimicrobial agent is exhausted. In the case of usage with and in carpet, in accordance with the method of the present invention, migration of bacteria and the like occurs outwardly, through the carpet and to the surface, as well as inwardly, toward and into the supporting surfaces, such as concrete, flooring, walls and the like.

In other words, by first laying down the non-woven antimicrobial barrier fabric against the floor, the floor is protected against becoming an environment and home to the micro-organisms. Bacteria and the like, passing downwardly through the carpet or other permeable floor covering, as well as various micro-organisms propagated from bodily fluids, will be controlled upon contact with the barrier fabric. As a result, passage of micro-organisms down into the floor and other support surfaces or substrates is inhibited, as is further

transmission of the micro-organisms to the surface of the carpet or floor covering where they can directly pass to humans, animals, equipment and the like.

Thus, once the fabric is applied beneath the floor covering, a through- and-through zone of inhibition is achieved which effectively controls or otherwise inhibits any organisms which may contact the carpet or are within the zone of inhibition. Consequently, the present invention provides antimicrobial activity in and around carpet or other coverings which reduces the labor of disinfecting such areas. A greater life can also be imparted to the carpet and, in turn, the contiguous flooring and wall surfaces, thereby reducing the interval between take-up and replacement, as well as the labor and material attendant thereto.

One floor covering that can house various organisms and which is subject to mold and mildew in damp environs is carpet. A typical carpet is denoted generally by the numeral 10 in Fig. 1. Such a carpet 10 inclues a plurality of face yarns 12 which are tufted or sewn into and through a primary backing fabric 14 and which are more securely held in place by the secondary backing fabric 16 attached to the backstitched side of primary backing fabric 14.

The secondary backing fabric 16 aids in providing improved dimensional stability and strength of the carpet and covers the back of the primary backing fabric 14.

A non-woven fabric 18 is placed between the floor 20 and carpet 10. Although depicted in use with carpet, it is to be appreciated that the non-woven fabric 18 could be utilized with other floor covering materials and possibly with some wall covering materials.

In Figs. 2-4, the use of the non-woven fabric barrier 18 of the present invention in other building environments has been presented. In Fig. 2, the fabric 18 has been applied to wall surfaces 22 prior to the application of wallpaper 24.

In Fig. 3, the fabric 18 has been applied to wall surfaces 26 of shower areas prior to the application of tile 28. In Fig. 4, the fabric 18 has been applied to base structure wall surfaces 30 prior to the application of exterior stucco 32. From the foregoing depictions, it is to be appreciated that the non-woven barrier fabric 18 could be utilized in many other applications where mold, mildew, bacteria and/or fungus and the like are desirably controlled.

In order to demonstrate practice of the invention, and in an effort to evaluate efficacy of the invention, the phenol-based antimicrobial agent,

Microban B, was added at a level of about approximately 5000 ppm during the extrusion process. More particularly, the antimicrobial agent was added at a rate of about 2.27 grams per pound of fiber. The resultant fiber was then extruded to about 0.04 to 60 DPF, with about 2 to 20 DPF being preferred and about 2 to 8 DPF being most preferred.

An actual field test was conducted in the Men's Locker Room of the Life Center exercise facility at the Greenville Hospital System, Greenville, S. C.

Areas were swabbed with six swabs each and sent to NAMSA Laboratories for total aerobic count. The general area tested was immediately at the exit of the shower room, which was damp to the touch. The two tests were: 1. The top of the carpet square.

2. Under the same square applied over the non-woven fabric of the present invention.

The carpet square was sold for commercial use as antimicrobial and was about 4 years old. The non-woven fabric underneath was installe approximately six months earlier. Upon removal of the carpet square, the dampness of the carpet surface was noticed as was a pronounced heavy sour odor in the area that became stronger when the carpet square that did not have the non-woven fabric underneath was removed. Results of the test are reported in Table I.

TABLEI SUMMARY OF NAMSA TESTS FOR TOTAL AEROBIC COUNT Test Numbers Location Results 1 Under Carpet High 120,000 Without Fabric Low 420 Ave. 95,000 2 Under Carpet High 29,000 With Fabric Low 330 Ave. 4,400 With reference to the values presented in Table I, it is apparent that the migration of mold and mildew to the under side of the carpet and adjacent floor area was significantly reduced in Test 2 by use of the non-woven barrier fabric 18. In particular, the average values show a reduction of almost 20 times the aerobic count.

Next, to demonstrate that the microbes pass through the carpet, or other material, are effectively controlled by the non-woven barrier fabric 18, four addition tests were conducted at the Greenville Hospital facility, results being reported in Colony Forming Units (CFU's), by using a modified AATCC 100 test on hard surfaces.

TABLEII SUMMARY OF NAMSA TESTS FOR COLONY FORMING UNITS Test Numbers Location Results 1 Top of Carpet High 5.0 CFU Without Fabric 2 Bottom of Carpet High 53.0 CFU Without Fabric 3 Top of Carpet High 8.0 CFU with Fabric 4 Bottom of Carpet High 7.0 CFU with Fabric With reference to the values presented in Table II, it is apparent that the migration of mold and mildew to the under side of the carpet and adjacent floor area was significantly reduced in Test 4, compared directly with Test 2, by use of the non-woven barrier fabric 18.

Interpretation of the foregoing results revealed that the carpet having no non-woven antimicrobial barrier fabric under it had very high levels of bioburden. The non-woven antimicrobial barrier fabric of the present invention showed good bioburden control after six months, despite having bioburden levels nearly 12 times higher in the unprotected area adjacent to it, and nearly 6 times higher on the surface of the same square. Previous conclusions that the carpet squares would not support significant bioburdens, and that the type of carpet backing would prevent water infiltration and significant bioburden growth, were at odds with the foregoing results.

Thus, it should be evident that the method of the present invention is useful in controlling the growth of bacteria, mold, mildew, fungus and the like.

Practice inclues the use of the non-woven fabric as described herein. The method and related components are particularly suited for use in commercial buildings and the like, but are not necessarily limited thereto, inasmuch as controlling mildew in damp basements, constitutes an important residential use.

It will be appreciated that the non-woven barrier fabric of the present invention can be manufactured with known equipment and methods, as well as with materials other than those disclosed herein. Moreover, the antimicrobial agents disclosed herein have been provided for purposes of exemplification only and thus, it is to be appreciated that other materials can be substituted without falling outside of the scope of this invention. Those skilled in the art can readily determine suitable antimicrobial agents and the appropriate manner of formulating synthetic fibers to contain such agents for the manufacture of non- woven fabrics according to the present invention.

Based upon the foregoing disclosure, it should now be apparent that the method and related components described herein will carry out the objects set forth hereinabove. It is, therefore, to be understood that any variations evident fall within the scope of the claimed invention and thus, the selection of specific component elements can be determined without departing from the spirit of the invention herein disclosed and described. Thus, the scope of the invention shall include all modifications and variations that may fall within the scope of the attached claims.