WO2016125173A1

WO2016125173A1 - Antimicrobial fabric materials for use in safety masks and personal protection clothing

Info

Publication number: WO2016125173A1
Application number: PCT/IL2016/050138
Authority: WO
Inventors: Mechael KANOVSKY
Original assignee: Argaman Technologies Ltd.
Priority date: 2015-02-08
Filing date: 2016-02-07
Publication date: 2016-08-11
Also published as: TW201630994A; CN107206023A

Abstract

The present invention relates to antimicrobial fabric materials suitable for use in protective masks, first responder protective clothing and hospital garments, said materials comprising a polymer having incorporated therein a synergistic combination of at least two metal oxide powders, comprising a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, the powders being incorporated substantially uniformly within said polymer, wherein the ions of the metal oxides are in ionic contact upon exposure of said material to moisture. There are further provided methods for the preparation of said materials.

Description

ANTIMICROBIAL FABRIC MATERIALS FOR USE IN SAFETY MASKS AND PERSONAL PROTECTION CLOTHING

FIELD OF THE INVENTION

The present invention refers to polymeric materials with antibacterial activity, which can be applied to protective masks, first responder protective clothing and hospital garments.

BACKGROUND OF THE INVENTION

It is widely known that crowded places (such as hospitals, healthcare facilities, food processing plants, hotels, dormitories, and public transportation) bear the potential risk of transferring diseases. Hence such places require use of products which are less prone to microbe and pathogen proliferation. As microbes evolve to be more pathogenic and drug resistant, the need to keep the bio-burden levels under control has increased, and more effective avenues of control need to be developed.

It has previously been shown that certain individual metal oxides, when exposed to moisture, will release ions to the environment in which the metal oxide is exposed. It is also known that these ions have antimicrobial, antiviral, and anti-fungal properties (Borkow and Gabbay, FASEB J. 2004 Nov;18(14):1728-30), as well as anti-mite qualities (Mumchuoglu, Gabbay, Borkow, International Journal of Pest Management, Vol. 54, No. 3, July-September 2008, 235-240). US Patent No. 6,645,531 to Antelman discloses pharmaceutical compositions that include a therapeutically effective amount of at least one electron active compound, or a pharmaceutically acceptable derivative thereof, that has at least two polyvalent cations, at least one of which has a first valence state and at least one of which has a second, different valence state. Preferred compounds include Bi(III,V) oxide, Co(II,III) oxide, Cu(I,III) oxide, Fe(II,III) oxide, Μη(ΙΙ,ΙΙΙ) oxide, and Pr(III,IV) oxide, and optionally Ag(I,III) oxide. Further provided are methods of halting, diminishing, or inhibiting the growth of at least one of a bacterium, a fungus; a parasitic microbe, and a virus, comprising administering to a human subject a therapeutically effective amount of the at least one electron active compound.

The use of textile fabrics to maintain low-risk of transferring diseases offers another level of protection by means of physical separation between the wearer and the surrounding environment. Furthermore, said fabrics can be fully customized depending on their mode of use, such as, for example, configured for single or multiple use.

US Patent No. 6,124,221 discloses an article of clothing having antibacterial, antifungal, and anti-yeast properties, comprising at least a panel of a metalized textile, said textile including fibers selected from the group consisting of natural fibers, synthetic cellulosic fibers, regenerated protein fibers, acrylic fibers, polyolefin fibers, polyurethane fibers, vinyl fibers, and blends thereof, and having a plating including an antibacterial, antifungal and anti-yeast effective amount of at least one oxidant cationic species of copper wherein the plating is bonded directly to the fibers.

US Patent No. 6,482,424 discloses a method for combating and preventing nosocomial infections, comprising providing to health care facilities textile fabrics incorporating fibers coated with an oxidant, cationic form of copper, for use in patient contact and care, wherein the textile fabric is effective for the inactivation of antibiotic resistant strains of bacteria.

US Patent No. 7,169,402 encompasses antimicrobial and antiviral polymeric materials, comprising a polymer selected from the group consisting of polyamide, polyester, and polypropylene, and a single antimicrobial and antiviral component consisting essentially of microscopic water insoluble particles of copper oxide incorporated in the polymer, wherein a portion of said particles in said polymer are exposed and protruding from the surface of the material, and wherein said particles release Cu²⁺ when exposed to water or water vapor.

US Patent 7,364,756 discloses a method for imparting antiviral properties to a hydrophilic polymeric material comprising preparing a hydrophilic polymeric slurry, dispersing an ionic copper powder mixture containing cuprous oxide and cupric oxide in said slurry and then extruding or molding said slurry to form a hydrophilic polymeric material, wherein water- insoluble particles that release both Cu⁺⁺ and Cu⁺ are directly and completely encapsulated within said hydrophilic polymeric material.

US Patent No. 6,436,420 to Antelman is related to fibrous textile articles possessing enhanced antimicrobial properties prepared by the deposition or interstitial precipitation of tetrasilver tetroxide (AgztOzt) crystals within the interstices of fibers, yarns and/or fabrics forming such articles.

Fabric material consists of a network of fibers which can be aligned or dispersed in a woven or non- woven fashion. Woven fabrics are produced by the interlacing of warp (0°) fibers and weft (90°) fibers in a regular pattern or weave style. The integrity of the fabric is maintained by the mechanical interlocking of the fibers. Weave style, which defines various fabric characteristics can include, inter alia, plain, twill, satin, basket, leno and mock leno.

A non- woven fabric is a fabric-like material made from stable or filament fibers, bonded together by chemical, mechanical, heat or solvent treatment. Non-woven fabrics are often classified according to the procedures used for their preparation, including, among others, water thorn non- woven fabric, thermal bonding non-woven fabric, pulp flow into nets non-woven fabric, wet non-woven fabric, spinning sticky non-woven fabric, weld spray non-woven fabric and sewing make up non-woven fabric.

Common fabric materials which can be utilized to promote antibacterial protection are non- woven fabrics, including spun-bond (SB) and melt blowing (MB) fabrics. Spun-bond (SB) fabric is formed by a continuous process in which a melted polymer is being used to form spun filaments, which in turn are directly dispersed into a web and going through further bonding and roll-up processes. Melt blowing (MB) fabric can be formed by passing a melt polymer through a net to form fibrous webs, using high-velocity air or another appropriate force to attenuate the filaments. This fabric is often characterized by a fine fiber diameter and lower mechanical strength.

Protective masks and clothing can be made of a woven or a non-woven fabric. In general, surgical masks are produced from a woven fabric, which can be configured for a multiple use, while respirators are generally produced from a non- woven material and intended for single use. One of the major problems of surgical masks and respirators is that they cannot be worn for more than a limited period of time before the holes in the filtration strata thereof get clogged by the wearer's nasal and mouth vapor, which clogs the holes in the filtration level making respiration difficult or impossible. Accordingly, the textile used in the preparation of the filter masks has to provide high breathability without compromising the filtering efficiency thereof.

US Patent No. 7,845,351 is directed to a face mask for reducing the amount of microbes to which a wearer is exposed, including a body portion that has an outer layer that has been treated with a germicidal agent in an effective amount.

US Patent No. 7,700,501 is directed to an adsorptive filtering material with biological and chemical protective function, in particular with protective function with regard to both chemical and biological poisons and noxiants, such as chemical and biological warfare agents, the adsorptive filtering material having a multilayered construction comprising a first outer supporting layer and a second outer supporting layer and an adsorptive layer disposed between the two supporting layers, the adsorptive filtering material further comprising at least one catalytically active component, the first outer supporting layer and/or the second outer supporting layer being provided with the catalytically active component.

International Patent Application No. WO 2009/146412 is directed to a facial mask for decreasing the transmission of one or more than one human pathogen to and from a human wearer of the facial mask. There is an unmet need for a cost-effective fabric material having improved antimicrobial and antiviral properties, which can be beneficially used in personal protective equipment or nosocomial applications. SUMMARY OF THE INVENTION

The present invention relates to fabric materials which have antimicrobial properties. Said fabrics are particularly suitable for use in air filtering systems of protective masks or as protection clothing items for personal protection of the wearer from harmful elements or for keeping the wearer from spreading harmful elements. The fabric material of the invention can be configured in varied thicknesses and surface densities which allow the customization of the mechanical properties of said fabric material to the desired mode of use, while maintaining the intrinsic antimicrobial properties intact.

The present invention is based in part on an unexpected discovery that the antimicrobial activity of a single oxidation state metal oxide is enhanced by the addition of a mixed oxidation state metal oxide, wherein the two metal ions are in ionic contact, such that the combination of the metal oxide powders provides a synergistic effect as compared to the activity of each of the metal oxides alone. It has further been surprisingly found that even the addition of the mixed oxidation state oxide in an amount of less than 10% wt. of the total weight of the combination provides synergistic antimicrobial effect.

It has further been found that incorporation of said combination of the metal oxide powders into a polymeric material, which is used in a fabrication of a facial mask, hospital garments or emergency protecting suits significantly reduces the exposure to pathogens.. In order to provide efficient antimicrobial protection, the metal oxides have to be embedded in the fabric material in a biocidially effective dose and be distributed throughout the polymeric material in a substantially uniform manner. Major challenges to homogeneous incorporation of inorganic particles into a polymeric material are particle agglomeration, chemical and physical interaction between the particles and the material and most of all by differences in the specific gravities of the particulate materials. In some embodiments, antimicrobial fabric materials of the present invention comprise particulate metal oxides having substantially different specific gravities, which are characterized by a generally homogeneous distribution of the metal oxide powders within the polymer material. The present invention overcomes the problem imposed by use of distinct types of metal oxides by equalizing the bulk densities of the metal oxide particles.

The fabric material of the present invention can comprise woven or non-woven fabric. The inventors have further found that using a composite fabric comprising spun-bond and melt- blown layers for the incorporation of the metal oxides allowed air-permeability approximately 3 times higher than that of the melt blown material of comparable weight, even though melt-blown material is a customary material used in protective masks. Accordingly, the material of the present invention can beneficially be used in user protective equipment, such as, but not limited to, protective masks.

According to one aspect, the present invention provides an antimicrobial fabric material comprising a polymer having incorporated therein a synergistic combination of at least two metal oxide powders, comprising a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, the powders being incorporated substantially uniformly within said polymer, wherein the ions of the metal oxides are in ionic contact upon exposure of said material to moisture.

According to some embodiments, the fabric material is a in a form selected from a woven material, a non-woven material or combinations thereof. Each possibility represents a separate embodiment of the invention.

In some embodiments, the present invention provides the fabric material in a form of a non- woven fabric. In further embodiments, the non-woven fabric is selected from the group consisting of a spun bond fabric, melt blown fabric and combinations thereof. Each possibility represents a separate embodiment of the invention. In particular embodiments, the non-woven fabric comprises a combination of a spun bond fabric and a melt blown fabric.

In certain embodiments, the fabric material comprises at least one layer of melt blown fabric. According to some embodiments, the at least one layer of melt blown fabric has a thickness of from about 5 microns to about 90 microns. In further embodiments, the at least one layer of melt blown fabric has a surface density of from about 5 g/m² to about 70 g/m². In yet further embodiments, the at least one layer of melt blown fabric has a mean pore size of at least about 30 μπι. The melt blown fabric material can comprise between 1 to 90 layers.

In certain embodiments, the fabric material comprises at least one layer of spun bond fabric. According to some embodiments, the at least one layer of spun bond fabric has a thickness of from about 5 microns to about 90 microns. In further embodiments, the at least one layer of spun bond fabric has a surface density of from about 5 g/m² to about 70 g/m². In yet further embodiments, the at least one layer of spun bond fabric has a mean pore size of at least about 30 μπι. The spun bond fabric material can comprise between 1 to 90 layers.

In some embodiments, the material comprises a spun bond-melt blown-spun bond (SMS) layered structure comprising a layer of a melt blown fabric disposed between two layers of a spun bond fabric. For convenience the structure of SMS is referred to as an SMS array. In some embodiments, each SMS array has a thickness of from about 5 microns to about 90 microns. In further embodiments, the SMS array has a surface density of from about 5 g/m² to about 70 g/m². In yet further embodiments, the SMS array has a mean pore size of at least about 30 μπι. In certain embodiments, the spun bond layer comprises a synergistic combination of at least two metal oxide powders incorporated therein. In certain embodiments, the melt-blown layer comprises a synergistic combination of at least two metal oxide powders incorporated therein. In further embodiments, the spun bond layer and the melt-blown layers comprise a synergistic combination of the at least two metal oxide powders incorporated therein. In some embodiments, the fabric material comprises from 1 to 90 SMS arrays.

In some embodiments, the present invention provides the fabric material in a form of a woven fabric. In some embodiments, the woven fabric of the invention has a surface area of from about 5 g/m² to about 70g/m². In additional embodiments, the woven fabric has a mean pore size of from about 20 μπι to about 60 μιη.

According to some embodiments, the polymer is selected from a synthetic polymer, naturally occurring polymer or combinations thereof. Each possibility represents a separate embodiment of the invention. According to some embodiments, the synthetic polymer is selected from the group consisting of organic polymers, inorganic polymers and bioplastics. In further embodiments, the polymer is selected from the group consisting of polyalkene, polyester, polyamide, polyaramide, cellulose-based polymer, and combinations thereof. The polyalkene may be selected from the group consisting of polypropylene, polyethylene and combinations thereof. Each possibility represents a separate embodiment of the invention. According to particular embodiments, the polymer is selected from polypropylene, polyethylene, polylactic acid (PLA), polyglycolic acid (PGA), poly(lactic-co-glycolic acid) (PLGA), cellulose-based polymer for use in the preparation of rayon or viscose, and combinations thereof. According to some exemplary embodiments, the polymer is selected from polyalkene or polyester.

In some embodiments, the spun bond fabric, the melt blown fabric or a combination thereof comprises polypropylene. Each possibility represents a separate embodiment of the invention. In other embodiments, the woven fabric comprises polypropylene.

According to some embodiments, the first metal and the second metal are different. In some embodiments, the mixed oxidation state oxide is selected from the group consisting of tetrasilver tetroxide (AgztOzt), Ag₃0₄, Ag₂0₂, tetracopper tetroxide (CU4O4), Cu (Ι,ΙΙΙ) oxide, Cu (11,111) oxide, CU4O3 and combinations thereof. Each possibility represents a separate embodiment of the invention. In some embodiments, the single oxidation state oxide is selected from the group consisting of copper oxide, silver oxide, zinc oxide and combinations thereof. Each possibility represents a separate embodiment of the invention. Copper oxide may be selected from the group consisting of cuprous oxide (Cu₂0), cupric oxide (CuO) and combinations thereof. Each possibility represents a separate embodiment of the invention. In particular embodiments, the combination of the at least two metal oxides comprises copper oxide and tetrasilver tetroxide. In further particular embodiments, copper oxide is cuprous oxide.

According to some embodiments, the mixed oxidation state oxide constitutes up to about 60% wt. of the total weight of the synergistic combination of the at least two metal oxide powders. According to further embodiments, the mixed oxidation state oxide constitutes up to about 15% wt. of the total weight of the synergistic combination of the at least two metal oxide powders. According to still further embodiments, the mixed oxidation state oxide constitutes from about 0.05% to about 15% wt. of the total weight of the synergistic combination of the at least two metal oxide powders. According to yet further embodiments, the mixed oxidation state oxide constitutes about 1% wt. of the total weight of the synergistic combination of the at least two metal oxide powders.

According to further embodiments, the mixed oxidation state oxide is present in the synergistic combination of the at least two metal oxide powders in a detectable amount. According to still further embodiments, the presence of the mixed oxidation state oxide in the material is detectable by means of an X-ray diffraction spectroscopy (XRD), electron microscopy, electron spectroscopy, Raman spectroscopy or electoanalytical methods. Each possibility represents a separate embodiment of the invention.

According to some embodiments, the metal oxide powders have substantially different specific gravities. According to further embodiments, the metal oxide powders have substantially similar bulk densities. According to further embodiments, the metal oxide powders having the substantially similar bulk densities comprise particles which mean particle size is inversely proportional to the specific gravity thereof. According to other embodiments, the metal oxide powders having the substantially similar bulk densities comprise particles which have substantially similar mean particles sizes and wherein said particles are coated with a coating. According to further embodiments, the coating thickness is proportional to the specific gravity of the metal oxide particles. In alternative embodiments, the coating weight is proportional to the specific gravity of the metal oxide powders. According to further embodiments, the coating comprises polyester or polyalkene wax. The polyester or polyalkene wax may be selected from the group consisting of a polypropylene wax, oxidized polyethylene wax, ethylene homopolymer wax and a combination thereof. Each possibility represents a separate embodiment of the invention. According to further embodiments, the metal oxide powders comprise particles, which are encapsulated within an encapsulating compound. The encapsulating compound may comprise silicate, acrylate, cellulose, derivatives thereof or combinations thereof. The non-limiting example of acrylate is poly(methyl methacrylate) (PMMA). According to the some exemplary embodiments, the encapsulating agent is a silicate or a poly(methyl methacrylate) (PMMA).

According to some embodiments, the material of the present invention further comprises a chelating agent or a metal deactivating agent associated with the metal oxide powders. The metal deactivating agent may be selected from the group consisting of phenolic antioxidant, potassium iodide, potassium bromide, calcium stearate, zinc stearate, aluminum stearate, tertiary chain extender and a combination thereof. Each possibility represents a separate embodiment of the invention.

According to further embodiments, the material of the present invention further comprises an additional component, selected from the group consisting of a surfactant, detergent, wetting agent, emulsifier, foaming agent, dispersant and combinations thereof. In some embodiments, said additional component is associated with the metal oxide powder. The surfactant may include a sulfate, a sulfonate, a silicone, a silane, or a non-ionic surfactant. The non-limiting examples of commercially available surfactants include Sigma Aldrich Niaproof®, Dow Corning Xiameter® and Triton-X-100.

In some embodiments, the combined weight of the at least two metal oxides constitutes from about 0.05% wt. to about 5% wt. of the total weight of the material.

In some embodiments, the material according to the principles of the present invention is for use in combating or inhibiting the activity of microbes or micro-organisms, selected from the group consisting of gram-positive bacteria, gram-negative bacteria, fungi and viruses. Each possibility represents a separate embodiment of the invention.

In another aspect, there is provided a material comprising a spun bond-melt blown-spun bond layered structure comprising a layer of a melt blown fabric disposed between two layers of a spun bond fabric, wherein at least one of the spun bond fabric and the melt blown fabric comprises a polymer having incorporated therein a synergistic combination of at least two metal oxide powders, comprising a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, the powders being incorporated substantially uniformly within said polymer, wherein the ions of the metal oxides are in ionic contact upon exposure of said material to moisture.

In some embodiments, the SMS array has a surface density of from about 5 g/m to about 100 g/m². In certain embodiments, the SMS array has a surface density of from about 10 g/m² to about 60 g/m . In further embodiments, each SMS array has a thickness of from about 5 microns to about 90 microns. In still further embodiments, the material has a thickness of from about 0.05 mm to about 0.5 mm. In certain embodiments, the spun bond layer comprises a synergistic combination of at least two metal oxide powders incorporated therein. In further embodiments, the spun bond layer and the melt-blown layers comprise a synergistic combination of the at least two metal oxide powders incorporated therein.

In some embodiments, the fabric material is for use in the protective masks. In certain such embodiments, the SMS array has a surface density of from about 5 g/m² to about 30 g/m². In further embodiments, each SMS array has a thickness of from about 5 microns to about 80 microns. In yet further embodiments, the material comprises from 1 to 40 SMS arrays.

In some embodiments, the fabric material is for use in the hospital garments. Said garments can be disposable. In certain such embodiments, the SMS array has a surface density of from about

2 2

15 g/m to about 40 g/m . In certain embodiments, the SMS array has a surface density of from about 20 g/m² to about 30 g/m². In further embodiments, each SMS array has a thickness of from about 5 microns to about 80 microns. In still further embodiments, the fabric material has a thickness of from about 0.2 mm to about 0.4 mm. In yet further embodiments, the material comprises from 5 to 40 SMS arrays .

In some embodiments, the fabric material is for use in the first responder suits. In certain such embodiments, the SMS array has a surface density of from about 50 g/m² to about 70 g/m². In further embodiments, each SMS array has a thickness of from about 5 microns to about 80 microns. In still further embodiments, the material has a thickness of from about 0.3 mm to about 0.5 mm. In yet further embodiments, the fabric material comprises from 10 to 90 SMS arrays. In another aspect, the present invention provides an air permeable protective mask comprising a fabric material comprising a polymer having incorporated therein a synergistic combination of at least two metal oxide powders, comprising a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, the powders being incorporated substantially uniformly within said polymer, wherein the ions of the metal oxides are in ionic contact upon exposure of said material to moisture.

In some embodiments, said protective mask comprises woven or non-woven fabric. Each possibility represents a separate embodiment of the invention. According to further embodiments, the protective mask fabric material has a maximal thickness of 3.2 mm. According to other embodiments, the protective mask fabric material is characterized by a surface density of from about 5 to about 30 g/m . In certain embodiments, the protective mask fabric material has an air permeability of from about 150 to about 6000 L/m . In some specific embodiments, the protective mask fabric material has an air permeability of at least about 3000 L/m³.

According to further embodiments, the protective mask in a form of a fold- flat surgical mask or a molded cup-shaped mask. Each possibility represents a separate embodiment of the invention. In further embodiments, the material is disposed in the filtering compartment of the mask. The protective mask can be configured for single use or multiple use.

In some embodiments, there is provided a fold-fiat surgical mask comprising the woven fabric. In further embodiments, the woven fabric comprises polypropylene or polyester. In further embodiments, the woven fabric comprises staple fibers. In further embodiments, the fabric has a surface density of from about 10 g/m² to about 30 g/m². In yet embodiments, the fibers have a mean thickness of from about 100 nm to about 100 μιη. In some embodiments, the staple polypropylene or polyester fabric comprises the synergistic combination of the at least two metal oxide powders incorporated therein. In some embodiments, the fold-flat surgical mask is configured for multiple use.

In some embodiments, there is provided a molded cup-shaped mask comprising the non- woven fabric. In further embodiments, the non-woven fabric comprises a combination of a spun bond fabric and a melt blown fabric. In further embodiments, the spun bond fabric, the melt blown fabric or a combination thereof comprises polypropylene. In yet further embodiments, the spun bond fabric and/or the melt blown fabric comprises a synergistic combination of at least two metal oxide powders incorporated therein. In still further embodiments, the non-woven fabric comprises a spun bond-melt blown-spun bond (SMS) array comprising a layer of a melt blown fabric disposed between two layers of a spun bond fabric. In some embodiments, the material comprises from 1 to 40 SMS arrays. In further embodiments, the non-woven fabric has an average pore size of from about 20 μπι to about 60 μπι. In yet further embodiments, the non- woven fabric has an air permeability of from about 150 to about 6000 L/m . In some embodiments, the molded cup-shaped mask is configured for single use.

According to some embodiments, the protective mask is for use in combating or inhibiting the activity of microbes or micro-organisms, selected from the group consisting of gram-positive bacteria, gram-negative bacteria, fungi and viruses. Each possibility represents a separate embodiment of the invention.

In another aspect, the present invention provides a personal protective clothing set comprising the fabric material comprising a fabric material comprising a polymer having incorporated therein a synergistic combination of at least two metal oxide powders, comprising a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, the powders being incorporated substantially uniformly within said polymer, wherein the ions of the metal oxides are in ionic contact upon exposure of said material to moisture.

According to some embodiments, said protective clothing set comprises a non-woven fabric material. According to further embodiments, the protective clothing set is in the form of a hospital garment. According to some embodiments, the protective hospital garment fabric material has a maximal thickness of 3.2 mm. According to other embodiments, the protective hospital garment fabric material is characterized by a surface density of from about 15 to about 40 g/m². According to other embodiments, the protective clothing set is in the form of a first responder suit. According to some embodiments, the protective first responder suit fabric material has a maximal thickness of 7.2 mm. According to other embodiments, the protective hospital garment fabric material is characterized by a surface density of from about 50 to about 70 g/m².

According to some embodiments, the personal protective clothing set is for use in combating or inhibiting the activity of microbes or micro-organisms, selected from the group consisting of gram-positive bacteria, gram- negative bacteria, fungi and viruses. Each possibility represents a separate embodiment of the invention.

In another aspect, the present invention provides a method for the preparation of an antimicrobial fabric material comprising a polymer having incorporated therein a synergistic combination of at least two metal oxide powders, comprising a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, the powders being incorporated substantially uniformly within said polymer, wherein the ions of the metal oxides are in ionic contact upon exposure of said material to moisture, the method comprising the steps of:

a. mixing the at least two metal oxide powders with the at least one polymer; and b. forming fibers from the obtained mixture,

preferably wherein step a. comprises producing a master batch, comprising the metal oxide powders and a carrier polymer.

According to some embodiments, said at least one polymer comprises the carrier polymer. According to the preferred embodiments, the master batch is homogeneous. The master batch may be formed into pellets. Alternatively, the master batch may be formed into granules.

In some embodiments step a. further comprises adding the master batch to a polymer slurry. In further embodiments the polymer slurry comprises a polymer, which is the same as the carrier polymer. In other embodiments, the polymer slurry comprises a polymer, which is chemically compatible with the carrier polymer. In some embodiments, step b. comprises extrusion or 3D printing. In some exemplary embodiments step b. comprises extrusion. In further embodiments, extrusion comprises spinning through a spinneret. In the preferred embodiments, the fibers are homogeneously extruded. According to further embodiments, the method comprises forming the fibers into a woven or non-woven fabric. Each possibility represents a separate embodiment of the invention. The non- woven fabric can include a spun-bond fabric, a melt-blown fabric or a combination thereof. The fibers can be formed into a non-woven fabric by a depositing the fibers on a collecting belt and bonding the fibers by applying heated rolls or hot needles. Each possibility represents a separate embodiment of the invention. In further embodiments, the fibers are separated during deposition by air jets or electrostatic charges. According to some embodiments, the method further includes combining the obtained fabric with an additional type of fabric. For example, the obtained fabric can include a spun-bond material, which can be combined with a melt-blown material.

According to some embodiments, the metal oxide powders have substantially different specific gravities. According to further embodiments, the method comprises a step of processing the at least two metal oxide powders to have substantially similar bulk densities prior to step a. According to some embodiments, the at least two metal oxide powders are processed to obtain particles having mean particles sizes which are inversely proportional to the specific gravity thereof. In some embodiments, said processing comprises grinding.

According to other embodiments, the at least two metal powders are processed to obtain particles having substantially similar sizes. In some embodiments, said processing comprises grinding. In additional embodiments, the metal oxide powders processing step further comprises applying a coating to the metal oxide powder particles. In some embodiments, the processing step, comprises applying a coating to the particles of at least one of the metal oxide powders. In further embodiments, the processing step comprises applying a coating to the particles of each of the at least two metal oxide powders. In further embodiments, the coating thickness is proportional to the specific gravity of the metal oxide powders.

In some embodiments, the method further comprises a step of encapsulating the metal oxide powder particles within an encapsulating compound. In other embodiments, the method comprises a step of mixing the metal oxide powders with a metal deactivating agent or a chelating agent. In further embodiments, the method comprises a step of mixing the metal oxide powders with a surfactant.

Further embodiments and the full scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description. BRIEF DESCRIPTION OF THE FIGURES

Figure 1A: SEM micrograph of a polyester staple fiber containing copper oxide and tetrasilver tetroxide, prepared by a master batch preparation method, at 1000X magnification with protruding particles.

Figure IB: SEM micrograph of a polyester staple fiber containing copper oxide and tetrasilver tetroxide, prepared by a master batch preparation method, at 4000X magnification with protruding particles.

Figure 1C: SEM micrograph of a cross section of the fiber of Figures 1A and IB, showing copper oxide and tetrasilver tetroxide at 4000X magnification with protruding particles.

Figure 2: SEM micrograph of a polyester staple fiber impregnated with copper oxide and tetrasilver tetroxide, via a sonication assisted process, at 20000X magnification with particles enclosed within the fiber.

Figure 3: SEM micrograph of a polypropylene woven fabric comprising copper oxide and tetrasilver tetroxide.

Figure 4: SEM micrograph of a polypropylene non- woven (spun bond) fabric comprising copper oxide and tetrasilver tetroxide.

Figures 5A-5C: Bacteria proliferation inhibition of the polymeric fabric comprising copper oxide and tetrasilver tetroxide, wherein solid color bars represent a polymeric fabric comprising a combination of copper oxide and TST, and confetti pattern bars represent control - untreated fabric of the same material and size. Figure 5A - Bacteria proliferation inhibition between 0 and 40 minutes from the exposure of the fabric to the bacteria containing medium, Figure 5B - Bacteria proliferation inhibition between 0 and 180 minutes from the exposure of the fabric to the bacteria containing medium, Figure 5C - Bacteria proliferation inhibition between 0 and 300 minutes from the exposure of the fabric to the bacteria containing medium.

Figure 6A-6B: Bacteria proliferation inhibition of the polymeric fabric comprising copper oxide, wherein grid pattern bars represent a polymeric fabric comprising copper oxide, and dotted pattern bars represent control - untreated fabric of the same material and size. Figure 6A - Bacteria proliferation inhibition between 0 and 40 minutes from the exposure of the fabric to the bacteria containing medium, and Figure 6B - Bacteria proliferation inhibition between 0 and 180 minutes from the exposure of the fabric to the bacteria containing medium. Figure 7A: Bacteria proliferation inhibition of the woven polypropylene fabric comprising copper oxide and tetrasilver tetroxide (dashed line) as compared to the control (solid line), which is untreated polypropylene and a polypropylene fabric comprising copper oxide alone (dotted line).

Figure 7B: Bacteria proliferation inhibition of the spun bond polypropylene fabric comprising copper oxide and tetrasilver tetroxide and control, which is woven, wherein stripes pattern bars represent polyester fabric made from a staple, comprising copper oxide and tetrasilver tetroxide, checker board pattern bars represent the control and dotted pattern bars represent a polypropylene fabric containing copper oxide only.

DETAILED DESCRIPTION

The present invention relates to fabric materials suitable for use in air filtering systems of protective masks, which afford high breathability without compromising protection to the wearer and particularly protection related to microbial deactivation. Furthermore, the fabric material of the invention is suitable for use as personal protective clothing, reducing significantly the exposure to potential pathogens. The present invention further provides a method for the fabrication of said materials. The antimicrobial fabric materials of the present invention are configured to destroy the microbes, which are present on the surface of the fabric and to deactivate the microbes, which pass through the fabric in the uniquely designed use of an air permeable mask filtering system. In the case of the use as a protective mask, the improved antimicrobial activity of the filter materials of the present invention is achieved without increasing the thickness and/or density of the filtering layers. The fabric materials of the present invention have improved antimicrobial properties, including increased antibacterial, antiviral, antifungal and antiparasitic activity. Said fabric materials can beneficially be used to increase biocidal efficiency of flat-fold and molded cup-shaped masks. The antimicrobial fabric materials of the present invention comprise a polymer and a synergistic combination of at least two metal oxide powders homogeneously incorporated into said polymer.

The present application incorporates by reference the specification of the International Patent Application No. PCT/IL2015/05014.

As used herein, the term "antimicrobial" refers to an inhibiting, microcidal or oligodynamic effect against microbes, pathogens, and microorganisms, including but not limited to enveloped viruses, non-enveloped viruses, gram-positive bacteria, gram-negative bacteria, fungi, parasites, mold, yeasts, spores, algae, protozoa, acarii and dust mites, amongst others, and subsequent anti- odor properties. The synergistic combination of the at least two metal oxide powders comprises a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, wherein the ions of the metal oxides are in an ionic contact upon hydration of said material or its exposure to residual moisture.

As used herein, the term "ionic contact" refers to the ability of ions of each of the metal oxide powders, being incorporated within the polymer, to flow to a mutual aqueous reservoir upon exposure to said reservoir.

The synergistic combination of two metal oxides

It has been surprisingly found that in order to improve antimicrobial properties of a single oxidation state metal oxide, a mixed oxidation state metal oxide compound should be added to the single oxidation state oxide. Without wishing to being bound by theory or mechanism of action, in order to provide the induced biocidal activity, the metal oxide particles should be mixed together in such a manner that the particles of each oxide are exposed to the same moisture reservoir, thus enabling a diffusion of ions from each metal oxide compound to the mutual moisture reservoir.

The synergistic combination of the two metal oxides, wherein at least one of the metal oxides is a mixed oxidation state oxide and at least one of the metal oxides is a single oxidation state oxide is a non-naturally occurring biologically active combination. According to some embodiments, said non-naturally occurring combination of metal oxides applied to a polymer substrate demonstrates greater ionic activity than the naturally occurring compounds alone. Without wishing to being bound by theory or mechanism of action, the increased ionic activity is responsible for a greater biocidal effect when compared to the equal amounts of naturally occurring metal oxide compounds under similar conditions.

As defined herein, the term "synergistic combination" refers to a combination of at least two metal oxides, which provides higher antimicrobial efficiency than the equal amount of each of the metal oxides alone. The higher antimicrobial efficiency may relate to accelerated bacteria or micro-organism killing rate.

The synergistic combination applied to a polymer comprises two or more biologically active relatively insoluble metal oxides, wherein at least one metal oxide is selected from single oxidation state oxide compounds, and at least one metal oxide is selected from mixed oxidation state oxide compounds has been found to be biologically active by itself and synergistic, providing surprisingly accelerated microbe mortality as compared to the same single and mixed oxidation state metal oxides individually, or combined within the single oxidation state group which are naturally occurring. As used herein, the term "mixed oxidation state" refers to atoms, ions or molecules in which the electrons are to some extent delocalized via various electronic transition mechanisms and are shared amongst the atoms, creating a conjugated bond which affects the physiochemical properties of the material. In the mixed oxidation state, electronic transitions form a superposition between two single oxidation states. This can be expressed as any metal that has more than a single oxidation state coexisting, as in the formula X (Y, Z), where X is the metal element and Y and Z are the oxidation states, where Y≠Z. The mixed oxidation state oxide may be one compound, wherein metal ions are in different oxidation states (i.e. X(Y,Z)).

According to some embodiments, the mixed oxidation state oxide useful in the materials of the present invention is selected from the group consisting of tetrasilver tetroxide (TST) - Ag₄0₄ (Ag I, III), Ag₃0₄, Ag₂0_2, tetracopper tetroxide - Cu₄0₄ (Cu I, III), Cu₄0_3, Cu (I, II), Cu (II, III), Co(II,III), Pr(III,IV), Bi(III,V), Fe(II,III), and Μη(ΙΙ,ΙΙΙ) oxides and combinations thereof. Each possibility represents a separate embodiment of the invention. In certain embodiments, the material comprises a mixed oxidation state oxide selected from the group consisting of tetrasilver tetroxide, tetracopper tetroxide and a combination thereof.

As used herein, the term "single oxidation state" refers to atoms, ions or molecules in which same types of atoms are present in one oxidation state only. For example, in copper (I) oxide copper all ions are in the oxidation state +1 , in copper (II) oxide all copper ions are in the oxidation state +2 and in zinc oxide all zinc ions are in oxidation state +2.

According to some embodiments, the single oxidation state oxide useful in the materials of the present invention is selected from the group consisting of copper oxide, silver oxide, zinc oxide and combinations thereof.

As used herein, the term "copper oxide" refers to either or both of copper oxide's multiple oxidation states: the first, principal single oxidation state cuprous oxide ((Cu₂0), also identified as copper (I) oxide); or the second, higher single oxidation state cupric oxide ((CuO), also identified as copper (II) oxide) either individually or in varying proportions of the two naturally occurring oxidation states.

As used herein, the term "silver oxide" refers to silver oxide's multiple oxidation states: the first, principal single oxidation state Ag₂0 (also identified as silver (I) oxide); or the second, higher single oxidation state AgO, (also identified as silver (II) oxide); or the third highest single oxidation state Ag₂(¾, individually or in any varying proportion of these three naturally occurring oxidation states.

As used herein, the term "zinc oxide" refers to zinc oxide's principal oxidation state Zn0₂. According to some embodiments, copper oxide is selected from the group consisting of Cu₂0, CuO and combinations thereof. According to further embodiments, silver oxide is selected from the group consisting of Ag₂0, AgO, Ag₂(¾ and combinations thereof. Each possibility represents a separate embodiment of the invention.

In certain embodiments, the material comprises a single oxidation state oxide selected from the group consisting of copper oxide, silver oxide and a combination thereof. In further embodiments, the single oxidation state oxide is copper oxide. In still further embodiments, the material comprises a single oxidation state oxide selected from the group consisting of Cu₂0, CuO and combinations thereof. Each possibility represents a separate embodiment of the invention. In certain embodiments, copper oxide is C¾0.

According to some embodiments, the metal oxides useful in the materials of the present invention are selected from the group consisting of copper oxide, tetracopper tetroxide, silver oxide, tetrasilver tetroxide, zinc oxide and combinations thereof. According to further embodiments, the metal oxides are selected from the group consisting of CU2O, CuO, CU4O4, Ag20, AgO, Ag202, Ag203, AgztO.4, Zn02 and combinations thereof. In particular embodiments, the material comprises at least two metal oxides selected from the group consisting of copper oxide, tetrasilver tetroxide, tetracopper tetroxide and combinations thereof. In the currently preferred embodiments, the single oxidation state oxide is copper oxide and the mixed oxidation state oxide is tetrasilver tetroxide. In further embodiments, the single oxidation state oxide is cuprous oxide and the mixed oxidation state oxide is tetrasilver tetroxide.

Combinations of copper oxide and zinc oxide are not known to provide synergistic antimicrobial effect. While acceleration of the antimicrobial effects of a naturally occurring copper oxide comprising a mixture of cupric and cuprous oxides was disclosed, for example, in US Patent No. 7,169,402, the present invention provides non- naturally occurring combinations of metal oxides, specifically combinations comprising a single oxidation state oxide combined with tetracopper tetroxide or tetrasilver tetroxide, such combinations being characterized by synergistic antimicrobial proliferation properties. Without wishing to being bound by theory or mechanism of action, the measured synergistic effect of such combinations can be attributed to intervalence charge transfer between the metal ions having different oxidation states. Exposure of the combination of the at least two metal oxides, comprising a mixed oxidation state oxide and a single oxidation state oxide, to a mutual moisture reservoir establishes ionic contact between the metal oxides and allows ion release from each metal oxide to the mutual moisture reservoir, thus providing acceleration of microbial mortality rates. According to further embodiments, the material of the present invention comprises a synergistic combination of at least two metal oxides according to the principles of the present invention, wherein each of the metal oxides can be present in the combination at a weight percent of from about 0.05% to about 99.95%, such as from about 0.1 % to about 99.9%, or from about 0.5% to about 99.5%. Each possibility represents a separate embodiment of the invention.

It has been surprisingly found that incorporation of a combination of a mixed oxidation state oxide and a single oxidation state oxide into a polymer, wherein the mixed oxidation state oxide is present in a weight percent of less than 10% in the total weight of the combination of the metal oxides was sufficient to cause the acceleration of antimicrobial activity of said polymer, as compared to each of the polymers comprising mixed oxidation state oxide and single oxidation state oxide alone. This was even more surprising since the total weight of the mixed oxidation state oxide in the polymer comprising the combination of the metal oxide powders was ten times lower than in the polymer comprising the mixed oxidation state alone.

Thus, according to some embodiments, the mixed oxidation state oxide constitutes from about 1 % to about 20% wt. of the total weight of the combination of the two metal oxides. According to yet further embodiments, the mixed oxidation state oxide constitutes from about 5% to about 15% wt. of the total weight of the combination of the two metal oxides. According to still further embodiments, the mixed oxidation state oxide constitutes about 10% wt. of the total weight of the combination of the two metal oxides.

According to other embodiments, the mixed oxidation state oxide constitutes up to about 60% wt. of the total weight of the combination of the two metal oxides, such as up to about 50% wt., up to about 40% wt., up to about 30% wt., up to about 20% wt. or up to about 15% wt. of the total weight of the combination of the two metal oxides. Each possibility represents a separate embodiment of the invention.

It has been further discovered that a polymer comprising as low as 3% wt. of the mixed oxidation state oxide in the metal oxides combination had increased biocidal activity as compared to the polymer comprising the single oxidation state oxide alone at the same weight percent of the metal oxide in the polymer as the weight percent of the metal oxides combination. It was also surprisingly found that antimicrobial activity of the material comprising a combination of the two metal oxides was enhanced as compared to the biocidal activity of single oxidation state oxide, even when the combination comprised as low 0.5% wt. of the mixed oxidation state oxide. Therefore, the mixed oxidation state oxide can beneficially be used in the material in a relatively low concentration, as compared to the single oxidation state oxide, thereby increasing commercial viability of the material. According to some embodiments, the mixed oxidation state oxide constitutes from about 0.05% to about 99.5% wt. of the total weight of the combination of the two metal oxides, such as from about 0.05% to about 90% wt., from about 0.05% to about 80% wt., from about 0.05% to about 70% wt., from about 0.05% to about 60% wt., from about 0.05% to about 50% wt., from about 0.05% to about 40% wt., from about 0.05% to about 30% wt., from about 0.05% to about 20% wt., or from about 0.05% to about 15% wt. of the total weight of the combination of the two metal oxides. Each possibility represents a separate embodiment of the invention.

According to further embodiments, the mixed oxidation state oxide constitutes from about 0.05% to about 15% wt. of the total weight of the combination of the two metal oxides, such as from about 0.1 % to about 15% wt., from about 0.5% to about 15% wt., from about 1 % to about 5% wt., from about 0.5% to about 5% wt., or from about 0.1 % to about 3% wt. of the total weight of the combination of the two metal oxides. Each possibility represents a separate embodiment of the invention.

According to particular embodiments, the mixed oxidation state oxide constitutes about 1 % wt. of the total weight of the combination of the two metal oxides. According to further particular embodiments, the mixed oxidation state oxide constitutes about 0.5% wt. of the total weight of the combination of the two metal oxides. According to still further particular embodiments, the mixed oxidation state oxide constitutes about 0.1% wt. of the total weight of the combination of the two metal oxides. According to yet further particular embodiments, the mixed oxidation state oxide constitutes about 0.05% wt. of the total weight of the combination of the two metal oxides. According to some embodiments, the antimicrobial effect of the combination of the two metal oxides is synergistic.

According to some embodiments, the mixed oxidation state oxide is present in the synergistic combination of the metal oxide powders in a detectable amount. The presence of the mixed oxidation state oxide in the synergistic mixture can be detected by means of an X-ray diffraction spectroscopy (XRD), electron microscopy, electron spectroscopy, Raman spectroscopy or electoanalytical methods. Electron spectroscopy includes, inter alia, X-ray photoelectron spectroscopy (XPS), electron spectroscopy for chemical analysis (ESCA and Auger electron spectroscopy (AES). The non-limiting example of electron microscopy method suitable for the detection of mixed oxidation state oxide is Scanning electron microscopy (SEM), optionally conjugated with Energy-dispersive X-ray spectroscopy (EDS). According to certain embodiments, the presence of the mixed oxidation state oxide is detected by XRD. The metal oxide powders

The copper oxide useful in the materials of the present invention can be any commercially available copper oxide powder with a purity level of no less than 97% wt. In some exemplary embodiments, the powder is purchased from SCM Inc. of North Carolina, USA. Due to the prevalence of suppliers of this powder it is not economically viable to manufacture the powder. The zinc oxide useful in the materials of the present invention can be any commercially available zinc oxide powder with a recommended purity level of no less than 98% wt. which is readily available commercially. However, due to the difficulty in obtaining tetrasilver tetroxide and/or tetracopper tetroxide, it is necessary to synthesize the specific species as described hereinbelow. According to some embodiments, the particle size of the commercially available metal oxide powder is from about 10 to about 20 micron. The metal oxide powder can be ground to a particle size of from about 1 nanometer to about 10 micron. Accordingly, the size of the metal oxide particles in the materials of the present invention can be from about 1 nanometer to about 10 microns. According to some embodiments, the particle size is from about 1 to 10 micron. According to further embodiments, the particle size is from about 5 to about 8 micron. According to other further embodiments, the particle size is from about 0.1 to about 0.5 micron. According to further embodiments, the particle size is from about 0.25 to about 0.35 micron According to some embodiments, the metal oxide powders comprise agglomerates which are no larger than 20 microns. According to other embodiments, the metal oxide powders comprise agglomerates which are no larger than 10 microns. In other embodiments, the materials of the present invention are devoid of metal oxide particles agglomerates.

The polymeric material

The synergistic combination of metal oxides can be incorporated into polymeric materials, which are suitable for air-filtration systems. Without wishing to being bound by theory or mechanism of action, the materials suitable for use in air filtering systems, such as protective masks, have to allow sufficient air permeability for user comfort, without decreasing filtering efficiency. It has been surprisingly found that the polymeric materials comprising the synergistic combination of metal oxides provided enhanced antimicrobial activity to the filters of facial masks without compromising breathability and the wearer comfort thereof.

As used herein, the term "polymer" or "polymeric" refers to materials consisting of repeated building blocks called monomers. The polymer may be homogenous or heterogeneous in its form; hydrophilic or hydrophobic; natural, synthetic, mixed synthetic or bioplastic. The non- limiting examples of polymers suitable for incorporation of the metal oxide powders include, inter alia, polyalkene, polyester, polyaramide, cellulose -based polymer or a mixture of different cellulose materials, converted cellulose mixed with plasticizers such as but not limited to rayon viscose, starch-based polymer, and acetate; and combinations thereof. Each possibility represents a separate embodiment of the invention.

According to some embodiments, the polymer is a synthetic polymer, including organic polymers, inorganic polymers and bioplastics. According to some embodiments, the polymer is selected from the group consisting of polyalkene, polyester, polyamide, polyaramide, cellulose- based polymers, starch-based polymer, derivatives, dispersions and combinations thereof. Each possibility represents a separate embodiment of the invention. The non-limiting examples of polyalkene include polypropylene and polyethylene. The non-limiting examples of the cellulose- based polymer are viscose or rayon. The non-limiting examples of the polyester include polylactic acid (PLA), polyglycolic acid (PGA), and poly(lactic-co-glycolic acid) (PLGA). The polymer may be water based or solvent based. Combinations of more than one of said materials can also be used provided they are compatible or adjusted for compatibility.

According to certain embodiments, the polymer is selected from the group consisting of polyalkene, polyester, cellulose-based polymers and combinations thereof. According to particular embodiments, the polymer is selected from polypropylene, polyethylene, PLA, PGA, PLGA, rayon, viscose and combinations thereof. In further embodiments, the polymer is selected from polypropylene and polyethylene. In some exemplary embodiments, the polymer is polypropylene.

The material according to the principles of the present invention can be in a form of a woven material, a non-woven material or a combination thereof. In certain embodiments, the material is in a form of a fabric or a textile. The terms fabric and textile can be used interchangeably. The fabric can be a woven or a non-woven fabric. In some embodiments, the woven fabric includes a knitted fabric. The term "non-woven fabric" is meant to encompass fabrics which are neither woven nor knitted.

In some embodiments, the material includes a plurality of fabric layers. In certain embodiments, the material includes from 1 to 100 layers. In further embodiments, the material includes from 1 to 70 layers, from 1 to 50 layers, from 1 to 40 layers, from 1 to 30 layers, from 1 to 20 layers or from 1 to 10 layers. In some exemplary embodiments, the material includes 1, 2, 3, 16, 24 or 36 layers. Each possibility represents a separate embodiment of the invention.

In some embodiments, the fabric includes a plurality of layers. In certain embodiments, the fabric includes from 1 to 10 layers. In further embodiments, the fabric includes from 1 to 9 layers, from 1 to 7, layers, from 1 to 5 layers or from 1 to 3 layers. In some exemplary embodiments, the fabric includes 3 layers. The fabric suitable for the filtration systems and the personal protecting clothing according to the principles of the present invention can have a surface density of from about 1 g/m² to about 500 g/m². In further embodiments, the fabric has a surface density of from about 2 g/m² to about 200 g/m 2 , of from about 5 g/m 2 to about 100 g/m 2 , of from about 5 g/m 2 to about 50 g/m 2 , of from about 5 g/m 2 to about 30 g/m 2 , of from about 7 g/m 2 to about 25 g/m 2 , or of from about 10 g/m 2 to about 20 g/m². Each possibility represents a separate embodiment of the invention.

The fabric suitable for the filtration systems according to the principles of the present invention can have a thickness of from about 2 microns to about 80 microns. The fabric can also be made heavier by layering the fabrics. The fabric suitable for the filtration systems and the personal protecting clothing according to the principles of the present invention can have a mean pore size of from about 5 μπι to about 100 μπι. In further embodiments, the fabric has a mean pore size of from about 15 μπι to about 100 μπι. Each possibility represents a separate embodiment of the invention. According to some embodiments, the pores are formed between the fibers of the woven or non-woven fabric. According to further embodiments, the pores are formed between the layers of the fabric.

The fabric suitable for the filtration systems and the personal protecting clothing according to the principles of the present invention can have an air -permeability of from about 50 L/m³ to about 10000 L/m³. In further embodiments, the fabric has an air-permeability of from about 100 L/m³ to about 8000 L/m³, of from about 150 L/m³ to about 6000 L/m³, of from about 200 L/m³ to about 5000 L/m³, or of from about 500 L/m³ to about 2500 L/m³. Each possibility represents a separate embodiment of the invention.

In some embodiments, the fabric material comprises staple fibers or polymer fibers. A staple fiber is a fiber of a standardized length, which can be twisted into a yarn. A filament fiber is a fiber that comes in continuous to near continuous lengths. Synthetic fibers can be manufactured as stable or filament fibers. If the filament fiber is cut into discrete lengths, it becomes staple fiber. According to some embodiments, the fiber comprises the at least two metal oxide powders incorporated therein.

The fiber can be obtained by an extrusion, molding, casting or 3D printing process. In certain embodiments, the fiber is an extruded fiber.

The fiber can have a nanometric or micrometric thickness. Nanometric fibers can be produced, for example, by electro spinning. Micrometric fibers can be produced, for example, by conventional spinning. In some embodiments, the fiber has a thickness of from about 10 nm to about 150 μπι. In further embodiments, the fiber has a thickness of from about 10 nm to about 50 nm, from about 50 nm to about 100 nm, from about 100 nm to about 100 μπι, from about 200 nm to about 50 μπι, or from about 500 nm to about 10 μιη. The term "thickness", as used herein, refers to a size of the fiber in the shortest dimension thereof. If the fiber has a circular or a circular-like cross section, the thickness refers to a diameter of the fiber.

According to some embodiments, the fabric material comprises a woven fabric. Woven fabrics are produced by the interlacing of warp (0°) fibers and weft (90°) fibers in a regular pattern or weave style. The integrity of the fabric is maintained by the mechanical interlocking of the fibers. Weave style, which defines various fabric characteristics can include plain, twill, satin, basket, leno and mock leno.

According to some embodiments, the woven fabric has a surface density of from about 1 g/m to about 70 g/m². In further embodiments, the woven fabric has a surface density of from about 2 g/m to about 60 g/m , of from 2 g/m to about 50 g/m , of from 2 g/m to about 40 g/m , of from about 5 g/m to about 30 g/m , of from about 7 g/m to about 25 g/m , or of from about 10 g/m to about 20 g/m . Each possibility represents a separate embodiment of the invention.

According to some embodiments, the woven fabric has a thickness of from about 2 microns to about 80 microns. The thickness can be increased by layering of multiple sheaths.

According to some embodiments, the woven fabric comprises staple fibers. In some embodiments, the fiber of the woven fabric has a thickness of from about 50 nm to about 150 μπι. In further embodiments, the fiber has a thickness of from about 100 nm to about 100 μπι, of from about 200 nm to about 50 μπι, or from about 500 nm to about 10 μπι.

According to some embodiments, the woven fabric comprises a polymer selected from the group consisting of polyalkene, polyester, polyamide, polyaramide, cellulose-based polymers, starch- based polymer, derivatives, dispersions and combinations thereof. Each possibility represents a separate embodiment of the invention. In certain embodiments, the fibers of the woven fabric are made of said polymer. In some exemplary embodiments, the polymer comprises polypropylene. In some exemplary embodiments, the polymer comprises a polyalkene, preferably a polypropylene. In other exemplary embodiments, the polymer comprises a polyester.

According to some embodiments, the material comprises a non-woven fabric. A non-woven fabric is a fabric-like material made from stable or filament fibers, bonded together by chemical, mechanical, heat or solvent treatment. The non-limiting examples of non-woven fabrics classified according to the procedures used for the preparation thereof, include water thorn non- woven fabric, thermal bonding non-woven fabric, pulp flow into nets non-woven fabric, wet non-woven fabric, spinning sticky non-woven fabric, weld spray non-woven fabric and sewing make up non-woven fabric. Non-woven fabrics comprising staple fibers are typically made in 4 steps. Fibers are first spun, cut to a few centimeters length, and put into bales. The staple fibers are then blended, "opened" in a multistep process, dispersed on a conveyor belt, and spread in a uniform web by a wetlaid, airlaid, or carding/crosslapping process. Staple non-woven fabrics can be bonded either thermally or by using resin. Bonding can be throughout the web by resin saturation or overall thermal bonding or in a distinct pattern via resin printing or thermal spot bonding.

According to some embodiments, the material according to the principle of the present invention comprises a spun-bond material, a melt-blown material or a combination thereof.

Spun-bond (SB) fabric can be produced by depositing extruded, spun filaments onto a collecting belt in a uniform random manner followed by bonding the fibers. The fibers can be separated during the web laying process by air jets or electrostatic charges. The collecting surface is usually perforated to prevent the air stream from deflecting and carrying the fibers in an uncontrolled manner. Bonding imparts strength and integrity to the web by applying heated rolls or hot needles to partially melt the polymer and fuse the fibers together. Since molecular orientation increases the melting point, fibers that are not highly drawn can be used as thermal binding fibers. Polyethylene or random ethylene-propylene copolymers can be used as low melting bonding sites.

Melt blowing (MB) is a process for producing fibrous webs or articles directly from polymers or resins using high-velocity air or another appropriate force to attenuate filament fibers. The MB process can be used to produce nano- or micro-fibers. MB fibers generally have thickness in the range of 2 to 4 μπι, although they may be as small as 0.1 μπι and as large as 10 to 15 μπι.

Melt-blown non- woven fabrics are typically produced by extruding melted polymer fibers through a spin net or die consisting of up to 40 holes per inch to form long thin fibers which are stretched and cooled by passing hot air over the fibers as they fall from the die. The resultant web can be collected into rolls and subsequently converted to finished products.

The SB and MB processes generally use similar equipment. The two major differences between a typical MB process and an SB process that uses air attenuation are: i) the temperature and volume of the air used to attenuate the filaments and ii) the location where the filament draw or attenuation force is applied. MB process uses large amounts of high- temperature air to attenuate the filaments. The air temperature is typically equal to or slightly greater than the melt temperature of the polymer. In contrast, the SB process generally uses a smaller volume of air close to ambient temperature to first quench the fibers and then to attenuate the fibers. In the MB process, the draw or attenuation force is applied at the die tip while the polymer is still in the molten state. Application of the force at this point is ideal for forming microfibers but does not allow for polymer orientation to build good physical properties. In the SB process, the force is applied at some distance from the die or spinneret, after the polymer has been cooled and solidified. Application of the force at this point provides the conditions necessary for polymer orientation and the resultant improved physical properties, but is not conductive to forming microfibers.

Melt-blown fabric can be added to a spun-bond fabric to form spun-melt-spun (SM) or a spun- melt-spun (SMS) material. In some embodiments of the invention the material comprises an SMS material, comprising a layer of the melt-blown fabric disposed between two layers of the spun-bond material, such alternating arrangement can be referred to as SMS array.

According to some embodiments, the at least two metal oxide powders are incorporated into the spun-bond layer. According to other embodiments, the at least two metal oxide powders are incorporated into the melt-blown layer. According to additional embodiments, the at least two metal oxide powders are incorporated into the spun-bond and melt -blown layer.

According to some embodiment, the fabric material comprises at least one layer of melt blown fabric. According to other embodiments, melt blown the at least one layer comprises between 1 to 200 layers. According to further embodiments, the at least one layer comprises between 1 to 90 layers. According to some embodiments, the at least one layer of melt blown fabric has a thickness of from about 5 microns to about 80 microns. According to further embodiments, the at least one layer of melt blown fabric has a surface density of from about 5 g/m² to about 70 g/m². According to yet further embodiments, the at least one layer of melt blown fabric has a mean pore size of from about 20 μπι to about 60 μπι. According to specific embodiments, the at least one layer of melt blown fabric has a mean pore size of at least about 30 μπι.

According to some embodiment, the fabric material comprises at least one layer of spun bond fabric. According to other embodiments, the at least one layer comprises between 1 to 200 layers. According to another embodiment, the at least one layer comprises between 1 to 90 layers. According to some embodiments, the at least one layer of spun bond fabric has a thickness of from about 5 microns to about 80 microns. According to further embodiments, the at least one layer of spun bond fabric has a surface density of from about 5 g/m² to about 70 g/m². According to yet further embodiments, the at least one layer of spun bond fabric has a mean pore size of from about 20 μπι to about 60 μπι. According to specific embodiments, the at least one layer of melt blown fabric has a mean pore size of at least about 30 μπι.

In some embodiments, the SMS material has a surface density of from about 5 g/m² to about 70 g/m . In some embodiments, the SMS material has a thickness of from about 2 microns to about 90 microns. In some embodiments, the SMS material has a mean pore size of at least about 30 μπι. In further embodiments, the SMS material has a mean pore size of at least about 40 μιη. In yet further embodiments, the SMS material has a mean pore size of at least about 50 μιη.

In some embodiments, the SMS material has an air-permeability of at least about 3000 L/m³. In further embodiments, the SMS material has an air-permeability of at least about 4000 L/m³. In yet further embodiments, the SMS material has an air-permeability of at least about 4500 L/m³. In still further embodiments, the SMS material has an air-permeability of at least about 5000 L/m³.

In some embodiments, the material includes a plurality of SMS arrays. In certain embodiments, the material includes from 1 to 90 SMS arrays. In further embodiments, the material includes from 1 to 40 SMS arrays. In other embodiments, the material includes from 10 to 90 SMS arrays. In some exemplary embodiments, the material includes 1 , 2, 3, 16, 24 or 36 SMS arrays. Each possibility represents a separate embodiment of the invention.

In some embodiments, the material including the plurality of SMS array has a surface density of from about 5 g/m² to about 400 g/m². In further embodiments, the material including the plurality of SMS arrays has a surface density of from about 5 g/m² to about 300 g/m². In still further embodiments, the material including the plurality of SMS arrays has a surface density of from about 5 g/m² to about 200 g/m². In yet further embodiments, the material including the plurality of SMS arrays has a surface density of from about 5 g/m² to about 100 g/m². In still further embodiments, the material including the plurality of SMS arrays has a surface density of

2 2

from about 5 g/m to about 500 g/m . In yet further embodiments, the material including the plurality of SMS arrays has a surface density of from about 5 g/m² to about 70 g/m².

In some embodiments, the material including the plurality of SMS arrays has a thickness of from about 2 microns to about 80 microns. In some embodiments, the material including the plurality of SMS arrays has a mean pore size of from about 10 μπι to about 70 μπι. In further embodiments, said material has a mean pore size of at least from about 20 μπι to about 60 μπι. In yet further embodiments, said material has a mean pore size of from about 20 μπι to about 50 μπι.

In some embodiments, the material including the plurality of SMS arrays has an air-permeability of from about 150 to about 6000 L/m³. In further embodiments, said material has an air- permeability of from about 150 L/m³ to about 4000 L/m³. In still further embodiments, said material has an air-permeability of from about 150 L/m³ to about 3000 L/m³. In yet further

3 3 embodiments, said material has an air-permeability of from about 150 L/m to about 2000 L/m . In still further embodiments, said material has an air-permeability of from about 150 L/m³ to about 1000 L/m . In yet further embodiments, said material has an air-permeability of from about 150 L/m³ to about 500 L/m³.

According to some embodiments, the non-woven fabric comprises a polymer selected from the group consisting of polyalkene, polyester, polyamide, polyaramide, cellulose-based polymers, starch-based polymer, derivatives, dispersions and combinations thereof. Each possibility represents a separate embodiment of the invention. In certain embodiments, the fibers of the non- woven fabric are made of said polymer. In some exemplary embodiments, the polymer comprises polypropylene. In some exemplary embodiments, the polymer comprises a polyalkene, preferably a polypropylene. In other exemplary embodiments, the polymer comprises polyester.

The polymer having the metal oxide powders incorporated therein

According to some embodiments, the metal oxide powders are incorporated into the polymer by a master batch manufacturing.

As used herein, the term "master batch" unless otherwise indicated, refers to a carrier polymer containing metal oxide particles, formed into pellets or granules, wherein the polymer is compatible with the end product material. The master batch can be added as a chemical additive to a polymeric slurry comprising same or chemically compatible polymer before extrusion, molding, casting or 3D printing. Alternatively, the master batch can comprise a compounded resin containing the final dosage of the polymers and the metal oxides required for the product to be formed from the polymer.

Metal oxide powders can be included in a polymer using a master batch system so that the powder particles form part of the entire polymeric product. However, the currently known processes for the preparation of a polymeric material having antimicrobial properties are adapted for inclusion of a single type of metal oxide. The present invention provides materials comprising a combination of a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal. According to some exemplary embodiments, the first metal and the second metal are different. Thus, according to further embodiments, the at least two metal oxide powders have substantially different specific gravities.

When two or more particulate compounds having different specific gravities and being disruptive to non-isotactic materials, such as the majority of polymers, have to be incorporated into the polymeric material, control over suspension and dispersion of the particles in the polymeric slurry is complicated. Such slurries generally yield inhomogeneous extruded or cast polymers. Dispersion and suspension of distinct metal oxide powders is not usually practiced in master batch production, where normally a specific single compound is desired to be added to the polymer. Therefore, when reducing the invention to practice, it was required to develop a method allowing incorporation of at least two metal oxide powders having substantially different specific gravities into a polymer fiber. Furthermore, since the amount of any metal oxide powder that can be incorporated into a polymer is limited by the disruption effect of the metal oxide on cross polymerization of non-isotactic polymers or weakening of the carrier polymer, it was necessary to develop a method to accommodate a high amount of multiple metal oxides in these polymers. The present invention thus provides a process for the preparation of the material having antimicrobial properties, providing control over the metal oxide particles concentration and distribution in the polymer. The present invention further provides materials having antimicrobial properties, comprising a combination of at least two metal oxide powders, wherein the metal oxide powders are incorporated within the polymer fiber in a generally uniform fashion. As used herein, the terms "generally uniform", "substantially uniform" or "homogeneous" that can be used interchangeably, denote that the volume percentage of the metal oxide particles on the polymer surface or in the bulk thereof varies by less than 20%, preferably less than 10%.

According to some embodiments, the materials of the present invention comprise at least two metal oxide powders having substantially different specific gravities. "Substantially different specific gravity" refers, in another embodiment, to the variance in the specific gravities of the at least two metal oxide powders, which is higher than about 5%. In another embodiment, the term refers to the variance of higher than about 10%. In yet another embodiment, the term refers to the variance of higher than about 15%.

To accommodate a plurality of metal oxide powders having distinct specific gravities in a single polymeric slurry, it is necessary to compensate for the particle weight differences of the metal oxides. In order to do so, the bulk densities of the metal oxide powders should be equalized. As used herein, the term "bulk density" refers to the mass of many particles of the powder divided by the total volume they occupy. According to some embodiments, the material comprises at least two metal oxides powders processed to have a substantially similar bulk density. "Substantially similar bulk density" refers, in some embodiments, to the variance in the bulk density of the at least two metal oxide powders, which is less than about 20%. In another embodiment, the term refers to the variance of less than about 10%. In yet another embodiment, the term refers to the variance of less than about 5%.

For example, specific gravity of copper oxide is 6.0 g/ml, wherein specific gravity of tetrasilver tetroxide is 7.48 g/ml. The bulk densities of the unprocessed copper oxide and the tetrasilver tetroxide powders are thus significantly different. Without wishing to being bound by theory or mechanism of action, in order to be incorporated into the polymer in a substantially uniform manner, the powders have to be processed to equalize the bulk densities thereof. Equalizing the bulk densities of the metal oxide powders can be achieved by altering the particle size of the metal oxide powders. Said particle size alteration can be performed by decreasing or increasing the particle size of the powders. For example, the particles size of the powders can be decreased by grinding and increased by applying a coating. The extent of the increase or decrease in the particle sizes of one metal oxide powder as compared to the other metal oxide powder is dependent on the specific gravities and/or the initial bulk densities of said metal oxide powders. According to some embodiments, the metal oxide powders are processed by grinding. In other embodiments, the metal oxide powders are processed by milling. According to certain embodiments, the metal oxide powders are processed to have mean particle sizes which are inversely proportional to the specific gravities thereof. According to another embodiment, the metal oxide powders are ground to have mean particle sizes which are inversely proportional to the specific gravities thereof. According to the further embodiments, the mean particle sizes of the metal oxide powders are inversely proportional to the specific gravity thereof.

According to further embodiments, the material comprises at least two metal oxide powders having essentially similar particle sizes. "Substantially similar particle size" refers, in another embodiment, to the variance in the particle size of the at least two metal oxide powders which is less than about 20%. In another embodiment, the term refers to the variance of less than about 10%. In yet another embodiment, the term refers to the variance of less than about 5%. In still another embodiment, the term refers to the variance of less than about 1 %.

According to further embodiments, the metal oxide powders are processed to have substantially similar particle sizes. According to further embodiments, the metal oxide powders are ground to have substantially similar particle sizes. According to yet further embodiments, at least one of the metal oxide powders is ground to obtain the at least two metal powders having substantially similar particle sizes.

According to some embodiments, the particles of at least one metal oxide powder comprise a coating. According to other embodiments, the particles of at least two metal oxide powders comprise the coating. In some embodiments, at least one of the metal oxide powders is processed to have coated particles. In further embodiments, each of the at least two metal oxide powders is processed to have coated particles. According to certain embodiments, said particles have substantially similar sizes. According to further embodiments, the coating thickness is proportional to the specific gravity of the metal oxide powders. According to yet further embodiments, the coating weight is proportional to the specific gravity of the metal oxide powders. According to some embodiments, the at least two metal oxide powders comprise particles having a different coating material. The molecular or specific weight of the coating material can be adjusted to compensate for the difference in the specific gravities of the metal oxide powders.

The metal oxide particles coating may comprise polyester or polyalkene wax. The non-limiting examples of the polyalkene wax include polypropylene wax marketed by Clariant as Licowax PP 230, an oxidized polyethylene wax marketed by Clariant as Licowax PED 521 , an oxidized polyethylene wax marketed by Clariant as Licowax PED 121 or an ethylene homopolymer wax marketed by BASF as Luwax ®.

According to further embodiments, the coating material comprises a copolymer of polyethylene wax and maleic anhydride. According to yet further embodiments, the coating material further comprises ionomers of low molecular weight waxes. According to additional embodiments, the polyethylene wax has a high wettability. In some embodiments, the coating material comprises homopolymers, oxidized homopolymers, high density oxidized homopolymers and co-polymers of polyethylene, polypropylene and ionomer waxes, micronized polyalkene waxes or mixtures thereof, as well as co-polymers of ethylene-acrylic acid and ethylene- vinyl acetate.

A critical prerequisite for the usability of such an additive concentrate is the correct choice of the wax component. Although it is not colored itself, it influences the performance of the additive concentrate. For more detailed information, reference may be made, for example, to the product brochure "Luwaxe.RTM.— Anwendung in Pigmentkonzentraten" about polyethylene waxes from BASF AG.

According to some embodiments, the weight of the coating material applied to the powder constitutes from about 0.2% to about 2% wt. of the metal oxide powder weight. According to additional embodiments, the weight of the coating material constitutes from about 0.2% to about 1 % wt. of the metal oxide powder weight, preferably from about 0.4 to about 0.5% wt. Each possibility represents a separate embodiment of the invention. In a certain embodiment, the weight of the coating material constitutes about 1% wt. of the metal oxide powder weight.

According to other embodiments, the first metal and the second metal are the same. According to further embodiments, the at least two metal powders have substantially similar bulk densities. Without wishing to being bound by theory or mechanism of action, in order to hinder a chemical interaction between the metal oxide powders and the carrier polymer or the polymer fiber, the metal oxides should be pretreated with an encapsulating compound. Said compounds isolate the metal oxides so that they will not interact with the polymeric material and are configured to abrade off the powder during product use. Thus, according to some embodiments, the materials of the present invention comprise metal oxide powders, comprising particles encapsulated within an encapsulating compound. The encapsulating compound can be selected from the group consisting of silicates, acrylates, cellulose, protein-based compounds, peptide-based compounds, derivatives and combinations thereof. In some embodiments, the encapsulating compound is selected from the group consisting of silicate, poly(methyl methacrylate) (PMMA) and a combination thereof.

According to some embodiments, the weight of the encapsulating compound applied to the powder constitutes from about 0.2% to about 2% wt. of the metal oxide powder weight. According to additional embodiments, the weight of the encapsulating compound constitutes from about 0.2% to about 1 % wt. of the metal oxide powder weight, preferably from about 0.4 to about 0.5% wt. Each possibility represents a separate embodiment of the invention.

Additionally or alternatively, the chemical interaction between the metal oxide powders and the carrier polymer or the polymeric support, can be hindered through addition of metal deactivating agents or chelating agents. As used herein, the terms "metal deactivating agents" and "chelating agents" that can be used interchangeably, refer to an agent generally comprising organic molecules containing heteroatoms or functional groups such as a hydroxyl or carboxyl, the agent acting by chelation of the metal to form inactive or stable complexes.

Thus, according to some embodiments, the materials of the present invention comprise a metal deactivating agent or a chelating agent. In further embodiments, the materials of the present invention comprise a metal deactivating agent or a chelating agent associated with the metal oxide powders. The non-limiting example of the said metal deactivating agents and/or chelating agents include a phenolic antioxidant, potassium iodide, potassium bromide, calcium stearate, zinc stearate, aluminum stearate, tertiary chain extenders and combinations thereof. According to a particular embodiment, the metal deactivating agent is a phenolic antioxidant. The phenolic antioxidant can be selected from, but not limited to 2',3-bis [[3-[3,5-di-tert-butyl-4- hydroxyphenyl] propionyl]] propionohydrazide marketed under the name Irganox ® MD 1024 by CIBA; Vitamin E (alpha-tocopherol) which is a high molecular weight phenolic antioxidant, marketed under the name Irganox ® E 201 by CIBA; Irganox ® B 1171 , marketed by CIBA, which is a blend of a hindered phenolic antioxidant and a phosphate; and combination thereof. According to certain embodiments, the metal deactivating agents abrade off the metal oxide particles upon hydration of the material.

According to some embodiments, the weight of the metal deactivating agent applied to the powders constitutes from about 0.2% to about 5% wt. of the metal oxide powder weight. According to additional embodiments, the weight of the metal deactivating agent comprises from about 0.5% to about 1% wt. of the metal oxide powder weight. In a certain embodiment, the weight of the metal deactivating agent constitutes about 1% wt. of the metal oxide powder weight.

According to further embodiments, the material of the present invention further comprises an additional component, selected from the group consisting of a surfactant, detergent, wetting agent, emulsifier, foaming agent, dispersant and combinations thereof. In some embodiments, said additional component is associated with the metal oxide powder.

Another difficulty in adding almost any inorganic compound to a polymeric material is particle agglomeration. Thus, according to some embodiments, the metal oxide particles of the present invention are treated by a surfactant to prevent metal oxide particles agglomeration. Therefore, according to some embodiments, the materials of the present invention comprise a surfactant. In further embodiments, the materials comprise a surfactant associated with the metal oxide powders. The non-limiting examples of the surfactant include but are not limited to Sigma Aldrich Niaproof®, Dow Corning Xiameter® and Triton-X-100. The surfactant may further comprise a solvent, such as but not limited to, methyl alcohol, methyl ethyl ketone, or toluene. According to some embodiments, the material is devoid of the surfactant.

According to some embodiments, the weight of the surfactant constitutes from about 0.05% to about 2% wt. of the metal oxide powder weight. In a certain embodiment, the weight of the surfactant constitutes about 0.5% wt. of the metal oxide powder weight.

In additional embodiments, the additional component is configured to increase moistening of the at least two metal oxide powders incorporated into the polymer, thereby increasing the antimicrobial efficiency thereof.

According to some embodiments, the composition of the master batch, comprising the polymer and the synergistic composition of the metal oxides is formed into a fiber. According to some embodiments, the master batch composition is formed into a fiber by means of extrusion, molding, casting or 3D printing of the polymer, comprising said synergistic combination. The fiber can be a staple fiber or a filament fiber. In further embodiments, the fiber is formed into a woven or a non-woven material. The non-woven material can include a spun-bond material, a melt-blown material or a combination thereof.

In some embodiments, the combined weight of the at least two metal oxides constitutes from about 0.25% to about 50% wt. of the total weight of the material. In further embodiments, the combined weight of the at least two metal oxides constitutes from about 0.5% to about 30% wt. of the total weight of the material. In yet further embodiments, the combined weight of the at least two metal oxides constitutes from about 1% to about 15% wt. of the total weight of the material. In still further embodiments, the combined weight of the at least two metal oxides constitutes from about 1 % to about 5% wt. of the total weight of the material. In some embodiments, the polymer is selected from polypropylene or polyester.

In some embodiments, the combined weight of the at least two metal oxides constitutes from about 0.25% to about 50% wt. of the total weight of the woven fabric. In further embodiments, the combined weight of the at least two metal oxides constitutes from about 0.5% to about 30% wt. of the total weight of the woven fabric. In yet further embodiments, the combined weight of the at least two metal oxides constitutes from about 1 % to about 15% wt. of the total weight of the woven fabric. In still further embodiments, the combined weight of the at least two metal oxides constitutes from about 1% to about 5% wt. of the total weight of the woven fabric. In some embodiments, the polymer is selected from polypropylene or polyester.

In some embodiments, the combined weight of the at least two metal oxides constitutes from about 0.25% to about 50% wt. of the total weight of the non-woven fabric. In further embodiments, the combined weight of the at least two metal oxides constitutes from about 0.5% to about 30% wt. of the total weight of the non- woven fabric. In yet further embodiments, the combined weight of the at least two metal oxides constitutes from about 1 % to about 15% wt. of the total weight of the non-woven fabric. In still further embodiments, the combined weight of the at least two metal oxides constitutes from about 1% to about 5% wt. of the total weight of the non-woven fabric. In some embodiments, the polymer is selected from polypropylene or polyester.

According to some embodiments, the material having antimicrobial properties comprises the polymer and a synergistic combination of the at least two metal oxide powders, wherein the powders are incorporated within the polymer. According to some embodiments, the metal oxides powders are attached to the polymer. According to further embodiments, the powders are attached to the polymer surface. According to other embodiments, the powders are embedded into the polymer. According to further embodiments, the powders are embedded into the polymer surface. According to other embodiments, the powders are deposited on the polymer surface. According to additional embodiments, the powders are inserted into the polymer. According to further embodiments, the powders are inserted into the polymer surface. According to further embodiments, the metal oxide powders particles protrude from the polymer surface. According to still further embodiments, at least part of the metal oxide powders particles protrudes from the polymer surface. According to some embodiments, at least 10% of the synergistic combination of the metal oxides is present on the surface of the polymer. According to further embodiments, at least 5% of the synergistic combination of the metal oxides is present on the surface of the polymer. According to still further embodiments, at least 1% of the synergistic combination of the metal oxides is present on the surface of the polymer. According to other embodiments, the powders are not exposed on the surface of the polymer. According to some embodiments, said polymer is in a form of a polymer fiber. In further embodiments, the polymer fiber is formed into a woven or a non- woven fabric.

The protective mask

The invention further provides a protective mask comprising the material according to the principles of the present invention. In some embodiments, the mask is a fold-flat surgical mask. In some embodiments, the mask is a molded cup-shaped mask. In further embodiments, the material according to the principles of the invention is disposed in the filtering compartment of the mask. The protective mask can be configured for single use or multiple use.

Protective masks are used in a wide variety of applications to protect the human respiratory system from particles suspended in the air, powders and solid or liquid aerosols, which can also include microbes and viruses. Protective masks are generally divided into two categories depending on the purpose of their use: masks which protect the wearer from harmful elements and masks which keep the wearer from spreading harmful elements. Therefore, each type of the mask has its defined purpose, although in some cases more than one protective level can be covered by the same mask.

Different designation of protective masks is generally reflected in distinct structures thereof, wherein two most common structures include fold-flat masks and molded cup-shaped masks.

Fold-flat masks, also termed surgical masks, are typically made from either a woven fabric or a non-woven material. Molded cup-shaped masks, also termed respirators, are typically made from non-woven materials.

Fold-flat surgical type masks, which can be kept flat until needed, are normally used by doctors to protect the patients from being infected by any bacteria or virus transferred by the doctor during an examination of a patient and are not designated for the protection of the wearer. Surgical masks typically contain a few layers of a woven textile or a non- woven material and are therefore highly breathable. In some cases, the masks are formed from one or more layers of air- permeable materials, typically from an inner layer, a filtering layer and a cover layer. The main disadvantage of such masks is a limited protection to the wearer or to those around the wearer. While breathing through such masks is easy, the filtration value thereof is relatively low.

Molded cup-shaped masks, are typically made from non-woven materials and normally used by people concerned with the removal of small particles, often dust and air pollution particles, from the air. Respirator masks are often made of a variety of layers of non- woven materials, including polymers and rubber, wherein each layer can impart a different quality to the mask. Many types of respirator masks exist, including, inter alia, FFP type masks and N type masks.

Filtering facepieces (FFPs) protect from respirable dust, smoke, and aerosols, however they offer no protection from vapor and gas. A respirator mask covers mouth and nose and is constructed of various filter materials and the mask itself, which is generally manufactured of rubber or silicon. Depending on the total leakage and filtering of particle sizes up to 0.6 μπι, respirator masks ranging from FFP1 through FFP2 to FFP3 offer breathing protection for various concentrations of pollutants. The total leakage is defined by the filter penetration and leakages in the mouth and nose area.

FFP1 class of respirator masks offers protection from atoxic and non-fibrogenic kinds of dust, characterized by the total leakage of up to 25%. FFP2 masks provide protection from firm and fluid deleterious kinds of dust, smoke, and aerosols with the total leakage amounting to a maximum of 11 %. FFP3 class of respirators protects from poisonous and deleterious kinds of dust, smoke, and aerosols with total maximum leakage of 5%.

An N95 respirator is a respiratory protective device designed to achieve a very close facial fit and very efficient filtration of airborne particles. The 'N95' designation means that when subjected to careful testing, the respirator blocks at least 95% of very small (0.3 micron) test particles. If properly fitted, the filtration capabilities of N95 respirators exceed those of face masks. However, even a properly fitted N95 respirator does not completely eliminate the risk of illness or death. In a typical N95 respirator the outer cover material protects the filtering layer from abrasive forces. The filtering layer is normally made from non-woven fibrous materials, typically from polyolefins, polyesters or polyamides, which are often present in a spun bond configuration. The surface density of said fabrics can vary from as little as 10 g/m² to as much as 30 g/m². The next inner layer usually has a shape-retaining function and is normally made from non- woven fabric, typically from polyester which supports only a formation layer.

Most respirators with a classification of FFP I or FFP 2 or N90 or N95 further include a filtration layer or series of layers. The most common N95 masks generally include a 30 g/m² melt blown material. Depending on the level of filtration desired, such masks include between 1 and 3 layers of the melt blown material.

When air passes through the respirator mask, the filtering layer removes the contaminants from the flow stream preventing the wearer from inhaling them. Analogously, the exhaled air, passing through the mask, is purged from pathogenous agents and from contaminants. However, since microbes can remain in the matrix of the mask itself and act as a reservoir of the pathogens which can be passed on to persons touching the mask, respirator masks do not prevent other persons from being exposed to said microbes. Normally, respirators are designed to filter out dust particles from the air which are greater in size than 0.1 - 0.3 microns. However, many microbes, particularly viruses, have substantially smaller sizes and can pass through the mask. Accordingly respirator masks do not protect the wearer himself from some types of microbes and viruses.

In order to increase anti-microbial protection of facial masks and respirators an anti-microbial agent can be included in the filtering layers of the mask.

The flat-folded form of face mask is generally constructed as a fabric which is rectangular in form and has pleats running generally parallel to the mouth of the wearer. Such constructions may have a stiffening element to hold the face mask away from contact with the wearer's face. Stiffening has also been provided by fusing a pleat across the width of the face mask in a laminated structure or by providing a seam across the width of the face mask.

The flat- fold mask can further be in a form of a pleated respirator which is centrally folded in the horizontal direction to form upper and lower opposed faces. The central pleat together with the pleats in opposed faces can form a self-supporting pocket.

The flat-fold mask can comprise a pocket of flexible filtering sheet material having a generally tapering shape with an open edge at the larger end of the pocket and a closed end at the smaller end of the pocket. The closed end of the pocket can be formed with fold lines defining a generally quadrilateral surface comprising triangular surfaces which are folded to extend inwardly of the pocket, the triangular surfaces facing each other and being in use, relatively inclined to each other.

The flat-fold mask can further be configured to overlie the lips and mouth of the wearer without a direct contact therewith.

According to some embodiments, the fold-fiat mask comprises a woven fabric comprising the at least two metal oxide powders incorporated therein. In some embodiments, the combined weight of the at least two metal oxides constitutes from about 0.25% to about 50% wt. of the total weight of the woven fabric, from about 0.5% to about 30% wt., from about 1 % to about 15% wt., or from about 1% to about 5% wt. of the total weight of the woven fabric. Each possibility represents a separate embodiment of the invention. In some embodiments, the polymer is selected from polypropylene or polyester.

In some embodiments, the woven fabric of the fold-fiat mast has a surface density of from about 10 g/m² to about 30 g/m². In additional embodiments, the woven fabric includes staple fibers. The thickness of the staple fibers can range from about 100 nm to about 100 μπι. According to further embodiments, the woven fabric comprises a polypropylene or polyester. In certain embodiments, the fold-flat mask comprises a polypropylene-based material.

In some embodiments, the fold-flat mask is reusable (i.e. configured for multiple use). In additional embodiments, the fold-flat mask can be washed essentially without decreasing the air- permeability and antimicrobial activity thereof.

Cup-shaped molded masks (also termed herein respirators) are generally preferred in instances where relatively high concentration levels of contaminants are present because the edge of the respirator can be brought into line contact with the user's face to establish a better seal than generally exists during use of flat masks. Cup-shaped molded masks are typically made of one or more fibrous layers that have been coated with a resin to enhance stiffness and help retain the molded, cup-shaped configuration. The resin-coated layers often adhere to each other after the molding process. Respirators having one or more relatively stiff layers can be provided with one or two strong head straps that pull the mask or respirator tightly against the face to establish a good seal.

According to some embodiments, the cup-shaped molded mask comprises a non-woven fabric comprising the at least two metal oxide powders incorporated therein. In some embodiments, the combined weight of the at least two metal oxides constitutes from about 0.25% to about 50% wt. of the total weight of the non-woven fabric, from about 0.5% to about 30% wt., from about 1 % to about 15% wt., or from about 1% to about 5% wt. of the total weight of the non-woven fabric. Each possibility represents a separate embodiment of the invention. In some embodiments, the polymer is selected from polypropylene or polyester.

The non-woven fabric of the cup-shaped molded mask can comprise a spun-bond fabric, a melt- blown fabric or a combination thereof. In certain embodiments, the non-woven fabric comprises an array of the SMS material. The at least two metal oxide powders can be incorporated into the spun-bond fabric of the SMS array, into the melt-blown fabric of the SMS array or into a combination thereof.

In some embodiments, the SMS array of the cup-shaped molded mask has a surface density of from about 5 g/m² to about 30 g/m². In further embodiments, the SMS array has a mean pore size of at least about 30 μπι. In yet further embodiments, the SMS array has an air permeability of at least about 3000 L/m³.

In further embodiments, the cup-shaped molded mask comprises 1-40 arrays of the SMS material. In certain such embodiments, the cup-shaped molded mask comprises a material having a mean pore size of from about 20 μπι to about 60 μπι. In yet further embodiments, said material has an air permeability of from about 150 to about 6000 L/m³. According to some embodiments, the non-woven fabric of the cup-shaped molded mask comprises at least one layer of melt blown fabric. According to another embodiment, the cup- shaped molded mask comprises between 1 to 90 layers. According to further embodiments, the at least one layer of melt blown fabric has a surface density of from about 5 g/m² to about 30 g/m². According to yet further embodiments, the at least one layer of melt blown fabric has a mean pore size of from about 20 μπι to about 60 μιη. According to specific embodiments, the at least one layer of melt blown fabric has a mean pore size of at least about 30 μπι. In further embodiments, said material has an air permeability of from about 150 to about 6000 L/m³. In yet further embodiments, the SMS array has an air permeability of at least about 3000 L/m .

According to some embodiment, the fabric material of the cup-shaped molded mask comprises at least one layer of spun bond fabric. According to another embodiment, the cup-shaped molded mask comprises between 1 to 90 layers. According to some embodiments, the at least one layer of spun bond fabric has a thickness of from about 5 microns to about 80 microns. According to further embodiments, the at least one layer of spun bond fabric has a surface density of from about 5 g/m² to about 70 g/m². According to yet further embodiments, the at least one layer of spun bond fabric has a mean pore size of from about 20 μπι to about 60 μπι. According to specific embodiments, the at least one layer of melt blown fabric has a mean pore size of at least about 30 μπι. In further embodiments, said material has an air permeability of from about 150 to about 6000 L/m³. In yet further embodiments, the SMS array has an air permeability of at least about 3000 L/m³.

According to further embodiments, the non-woven fabric comprises a polypropylene or polyester. In certain embodiments, the cup-shaped molded mask comprises a polypropylene- based material.

In some embodiments, the cup-shaped molded mask is disposable (i.e. configured for single use). The materials of the present invention have antimicrobial activity. The materials of the present invention can be used in combating or inhibiting the activity of microbes or micro-organisms, including, but not limited to, gram-positive bacteria, gram-negative bacteria, fungi, parasites, mold, spores, yeasts, protozoa, algae, acarii, and viruses. Thus, according to some embodiments, the present invention provides a protective mask for use in combating or inhibiting the activity of microbes or micro-organisms, selected from the group consisting of gram-positive bacteria, gram-negative bacteria, fungi, parasites, mold, spores, yeasts, protozoa, algae, acarii and viruses. Each possibility represents a separate embodiment of the invention. In further embodiments, the mask is for use in decreasing exposure of the wearer to microbes or micro-organisms, selected from the group consisting of gram-positive bacteria, gram-negative bacteria, fungi, parasites, mold, spores, yeasts, protozoa, algae, acarii and viruses.

The protective clothing

The invention further provides personal protective clothing set comprising the material according to the principles of the present invention._The protective clothing of the invention can be configured for single use or multiple use. According to some embodiments, the protective clothing of the invention is useful for combating or inhibiting microbial or micro-organism activity.

In some embodiments, the protective clothing can be in a form of a hospital garment. Hospital garments can be used for both protecting the wearer from harmful elements and keeping the wearer from spreading harmful elements. Such hospital garments may include medical gowns, scrubs, robes, shoes, slippers, surgical suits and hats. According to further embodiments, the protective hospital garment fabric material has a maximal thickness of 3.2 mm. According to other embodiments, the protective hospital garment fabric material is characterized by a surface density of from about 15 to about 40 g/m².

According to other embodiments, the protective clothing can be in a form of a first responder suit useful for personal protection of the wearer. According to some embodiments, the protective first responder suit fabric material has a maximal thickness of 7.2 mm. According to other embodiments, the protective hospital garment fabric material is characterized by a surface density of from about 50 to about 70 g/m².

Preparation method

In another aspect, the present invention provides a method for the preparation of the material according to the principles of the present invention, the method comprising the steps of:

a. mixing the at least two metal oxide powders with the at least one polymer;

b. forming fibers from the obtained mixture,

According to some embodiments, said at least one polymer comprises the carrier polymer. According to the preferred embodiments, the master batch is homogeneous. According to additional embodiments, the metal oxide powders are distributed in the master batch in a generally uniform manner. The master batch may be formed into pellets. Alternatively, the master batch may be formed into granules. The carrier polymer may be selected from the group consisting of polyamide, polyalkene, polyester and combinations thereof. In some embodiments step a. further comprises adding the master batch to a polymer slurry. In further embodiments the polymer slurry comprises a polymer, which is the same as the carrier polymer. In other embodiments, the polymer slurry comprises a polymer, which is chemically compatible with the carrier polymer. In some embodiments, the polymer is selected from the group consisting of polyalkene, polyester, polyamide, polyaramide, and cellulose-based polymers. Combinations of more than one of said materials can also be used provided they are compatible or adjusted for compatibility. The polymeric raw materials are usually in a bead form and can be mono-component, bi-component or multi-component in nature. The beads are heated to melting at a temperature which preferably will range from about 120°C to 180°C for isotactic polymers and up to 270°C for polyester. The master batch is then added to the polymer slurry and allowed to spread through the heated slurry. The particle size of the metal oxide powders in these embodiments is preferably between 1 and 5 microns. However particulate size can be larger when the fiber thickness can accommodate larger particles.

According to some embodiments, the metal oxides are incorporated directly into the polymer. According to further embodiments, particle size of the metal oxide powders is between 0.1 and 0.5 microns. According to still further embodiments, incorporation of the metal oxide powders into the polymer fiber is assisted by sonication.

According to some embodiments, said method includes a step of processing the at least two metal oxide powders to have substantially similar bulk densities prior to mixing the powders with the polymer. According to some embodiments, said step includes processing the metal oxide powders to obtain particles having sizes which are inversely proportional to the specific gravity thereof. According to some embodiments, said step comprises reducing the metal oxide powders particle size to obtain particles having sizes which are inversely proportional to the specific gravity thereof. According to other embodiments, said step comprises processing the metal oxide powders to obtain particles having substantially similar sizes. According to other embodiments, said step comprises reducing the metal oxide powders particle size to obtain particles having substantially similar sizes. In some embodiments, said processing comprises grinding.

In additional embodiments, the step of processing the at least two metal oxide powders further comprises applying a coating to the metal oxide powder particles. According to some embodiments, the coating thickness is proportional to the specific gravity of the metal oxide particles. According to other embodiments, the coating weight is proportional to the specific gravity of the metal oxide particles. According to some embodiments, the coating is applied to metal oxide powders having substantially similar particle sizes. According to further embodiments, the coating is applied to at least one metal oxide powder. According to other embodiments, the coating is applied to at least two metal oxide powders. According to further embodiments, the coating comprises polyester or polyalkene wax. The polyester or polyalkene wax may be selected from the group consisting of a polypropylene wax, oxidized polyethylene wax, ethylene homopolymer wax, and different types of waxes including copolymers of polyethylene wax and maleic anhydride which can also be used with ionomers of low molecular weight waxes or any combination thereof.

In some embodiments, the method further comprises a step of encapsulating the metal oxide powder particles within an encapsulating compound. In other embodiments, the method comprises a step of mixing the metal oxide powders with a metal deactivating agent or a chelating agent. In further embodiments, the method comprises a step of mixing the metal oxide powders with an additional component, selected from the group consisting of a surfactant, detergent, wetting agent, emulsifier, foaming agent, dispersant and combinations thereof. In particular embodiments, the method comprises a step of mixing the metal oxide powders with a surfactant. In some embodiments, the additional steps are performed prior to mixing the metal oxide powders with the polymer.

The encapsulating compound may be selected from the group consisting of silicate, acrylate, cellulose, derivatives thereof and combinations thereof. The metal deactivating agent may be selected from the group consisting of phenolic antioxidant, potassium iodide, potassium bromide, calcium stearate, zinc stearate, aluminum stearate, tertiary chain extender and a combination thereof. According to further embodiments, the material of the present invention further comprises an additional component, selected from the group consisting of a surfactant, detergent, wetting agent, emulsifier, foaming agent, dispersant and combinations thereof. In some embodiments, said additional component is associated with the metal oxide powder.

Another difficulty in adding almost any inorganic compound to a polymeric material is particle agglomeration. The surfactant can be selected from Sigma Aldrich Niaproof®, Dow Corning Xiameter® and Triton-X-100.

In additional embodiments, the method comprises preparing the mixed oxidation state oxide. The mixed oxidation state oxide can be prepared by a standard procedure, for example as described by Hammer and Kleinberg in Inorganic Synthesis (IV,12) or in US Patent No. 5,336,416, which are incorporated by reference herein in their entirety. The method may further include a step of grinding the obtained mixed oxidation state oxide powder.

According to some embodiments, the mixing of the metal oxide powders and the at least one polymer is assisted by sonication. In some embodiments, step b. comprises extrusion, molding, casting or 3D printing of the mixture obtained in step a. In some exemplary embodiments step c. comprises extrusion. In certain such embodiments, the polymer slurry is transferred to an extrusion tank. In further embodiments, the liquid polymer slurry is pushed through holes in a series of metal plates formed into a circle called a spinneret. The polymer slurry is pushed through a spinneret by applying pressure on the slurry. As the slurry is pushed through the fine holes they form single fibers. The hot liquid fiber is pushed upwards, cooled with cold air, forming a continuous series of fibers. The thickness of the fibers is controlled by the size of the holes and speed at which the slurry is pushed through the holes and upward by the cooling air flow. In the preferred embodiments, the fibers are homogeneously extruded.

The formation of the fiber can be in either filament form (continuous) or staple form (short cut). In both cases an amount of master batch is added to the hot polymeric slurry to yield the final amount of the combination of the at least two metal oxide powders desired for the end product. By way of example if a 1% final load is desired in a filament fiber, then 50 kilo of a 20% wt. concentrated master batch will be added to complete 1 ton of total slurry. By way of example if a 3% final load is desired in a staple fiber than 150 kilo of a 20% wt. concentrated master batch will be added to complete 1 ton of total slurry. In both cases, after a thorough mixing of the concentrated master batch in the slurry tub to obtain good master batch dispersion, the extruded fibers will contain the desired amount of the metal oxides combination.

In a normal process as known to those familiar with the art, the active ingredient will be evenly dispersed and remain in suspension of the polymeric slurry. If the master batch is not prepared correctly then the metal oxides will interact with the target polymer and disrupt the linkage process thus inhibiting the formation of a solid fiber. In addition, if the wax is not applied correctly the metal oxides will either sink to the bottom of the mixing tub and block the holes of the spinneret or will remain floating at the top of the slurry and not get mixed into the fibers. Normally extrusion is done using gravity so that the weight of the slurry in the tub pushes the polymer through the spinneret holes. The polymer is designed to solidify with exposure to air. Once the fibers are exposed to air they are wound on bobbins for further processing.

According to some embodiments, the fiber is selected from the group consisting of a staple fiber, a filament fiber and a combination thereof. According to some embodiments, the polymer fiber is a synthetic or a semi- synthetic fiber. According to further embodiments, the synthetic or semisynthetic fiber is selected from the group consisting of polyolefin fibers, polyurethane fibers, vinyl fibers, nylon fibers, polyester fibers, acrylic fibers, cellulose fibers, regenerated protein fibers, blends and combinations thereof. In some embodiments, the method further comprises blending the polymer fiber with a natural fiber. According to further embodiments, the natural fibers are selected from the group consisting of cotton, silk, wool, linen and combinations thereof.

According to further embodiments, the method includes forming the polymer fiber into a fabric. The fabric can be woven or non-woven. According to some embodiments, the method includes forming a spun-bond fabric, a melt-blown fabric or a combination thereof.

The fibers can be formed into a non-woven fabric by a depositing the fibers on a collecting belt. In further embodiments, said step comprises bonding the fibers by applying heated rolls or hot needles. Each possibility represents a separate embodiment of the invention. In yet further embodiments, the fibers are separated during deposition by air jets or electrostatic charges. In additional embodiments, the collecting belt surface is perforated.

According to some embodiments, the method further includes combining the obtained fabric with an additional type of fabric. For example, the obtained fabric can include a spun-bond material, which can be combined with a melt-blown material.

The following examples are presented for illustrative purposes only and are to be construed as non- limitative to the scope of the invention.

EXAMPLES

EXAMPLE 1: Mixed oxidation state oxide powder preparation.

A tetrasilver tetroxide powder was prepared through a reduction process from a silver nitrate solution by a standard procedure known to a person skilled in the art, and as described by Hammer and Kleinberg in Inorganic Synthesis (volume IV, page 12). It should be further noted that the powder obtained by the described process should be very soft and capable of being converted into a nano-powder with a relative ease.

The basic tetrasilver tetroxide (AgztOzt) synthesis as referenced above was prepared by addition of NaOH into distilled water, followed by addition of a potassium persulfate and then the addition of silver nitrate.

A tetracopper tetroxide powder can be prepared using copper sulfate and potassium persulfate as an oxidizing agent, as described in US Patent 5,336,416 to Antelman. However, for the sake of commercial viability cuprous oxide was purchased and used as a starting material to obtain CU4O4 according to the described procedure.

The particle size of both powders received varies from nano-particles to agglomerated particles as large as 20 microns.

These powders can be ground down to the desired particle size and mixed either together or with copper oxide or zinc oxide. The copper oxide used in the development is a cuprous oxide (brown/red) with a purity level of no less than 97% in a 10-20 μηι size particle. In this case, the powder was purchased from SCM Inc. of North Carolina, USA, but can be purchased from any supplier who can furnish this purity level. The powder is then ground down to 1 to 5 μιη. Due to the prevalence of suppliers of this powder it is not economically viable to manufacture the powder. However, due to the difficulty in obtaining tetrasilver tetroxide and/or tetracopper tetroxide, it is necessary to synthesize the specific species as described hereinabove.

EXAMPLE 2: Master batch preparation.

The metal oxides were incorporated into a polymer using a master batch system so that the powder is embedded on the outside of the polymer and forms part of the entire polymeric product.

To accommodate the different specific gravities of more than one metal oxide in a common master batch, it is necessary to compensate for the differences between the two different metals, should a difference in their weight exist. This is done using two systems as described:

In the first system, the particle sizes of each metal oxide were made equal through proportional size equalization. The specific gravity of copper oxide is approximately 6 g/ml and the specific gravity of tetrasilver tetroxide is 7.48 g/ml. Tetrasilver tetroxide particles were ground down to be approximately 10% to 15% smaller than the copper oxide particles.

In the second system, the particles were all ground to the same size but the heavier particles were coated with a higher amount of polyester wax or polyethylene wax.

The wax was applied in a high sheer mixer in a weight/weight ratio of approximately 10 grams wax to 1000 grams metal oxide. It was found that a higher amount of polyester wax on the heavier metal oxide aids in maintaining the suspension of the metal oxide in the polymer slurry. The wetting capability of the waxes should also be good. To isolate the metal oxide from a chemical interaction with the carrier polymer, the metal oxide powders were pretreated with an encapsulating compound. The inert encapsulating compounds used were a silicate and Poly(methyl methacrylate) (PMMA). The encapsulation was performed in a high sheer mixer in a weight/weight ratio of approximately 4g encapsulating agent to 1000 g metal oxide powder.

EXAMPLE 3: Polymer fiber preparation.

The fabrication of polymeric filament and staple fibers is described hereinbelow.

Filament fiber

It is noted that the specific gravity of each metal oxide is different and therefore required a treatment of a different coating compound or applying different amount of the same coating compound so that both metal oxide powders would be homogeneously dispersed in the liquid polyester slurry. The metal oxide particles were mixed with the carrier and formed into pellets. As it relates to filament fiber this produced a total of 50 kilo of master batch which is a total of the copper oxide and/or the tetrasilver and/or tetracopper tetroxide is together. The proportion of the carrier to active material was 5: 1 yielding a 20% wt. concentration of the metal oxides in the master batch. 50 kilo of the master batch were mixed into an extrusion tank for spinning through a spinneret and were sufficient to produce 1 ton of a filament polymeric fiber yielding a total of a 1 % final concentration of the two metal oxides (active material) together in the polymeric fiber. It should be noted that if the particles are below 0.5 microns in size it was found that the loading of the metal oxides in a filament fiber can be increased to as much as 4% wt.

Staple fiber with protruding metal oxide powders

For the production of a staple fiber, 28.5 kilo of copper oxide having particle size ground to 1 to 5 microns and 1.5 kilo of tetrasilver tetroxide ground to 1 to 5 microns were mixed with 120 kilo of the chosen carrier polyester polymer for the creation of a master batch. The specific gravity of each compound was different and therefore required a coating by a different coating compound, such as Clariant Licowax PP230 and BASF Luwax ® or by different amounts of said compounds, such that the metal oxide particles would be homogeneously dispersed in the suspension. The compounds were mixed with the carrier and were formed into pellets. This produced a total of 150 kilo of master batch. The 150 kilo of master batch was mixed into an extrusion tank for spinning through a spinneret and was sufficient to produce 1 ton of a polymeric staple yarn yielding a total of a 3% wt. final concentration of the two compounds in the polymer fiber.

Figures 1A-1C represent Scanning Electron Microscope (SEM) micrographs of a polyester staple fiber having a combination of copper oxide and tetrasilver tetroxide powders incorporated within. The polymer fiber was prepared by a master batch process as described hereinabove. It can be seen that the metal oxide particles are uniformly distributed on the surface of the polymer fiber. It can also be seen that the metal oxide particles of the synergistic combination protrude from the surface of said polymer fiber.

Staple fiber with enclosed metal oxide powders

A polyester staple fiber was prepared by combining copper oxide powder which constituted 2.85% wt. of the total weight of the fiber and tetrasilver tetroxide powder which constituted 0.015% wt. of the total weigh of the fiber. The particle size of the metal oxides was brought down to between 0.25 to 0.35 microns and the powders were incorporated directly into the polymer fiber. The process included milling the powders to the desired size, placing the powders on the fiber and passing the fiber with the powders through a trough of water though which ultrasonic waves were passed. Figure 2 shows SEM micrograph of the fibers obtained via said process, wherein the copper oxide and TST particles are under the surface which appear as unclear white spots in the SEM micrograph. Particles on the fibers surface in the photographs were evaluated by a spectrographic reading and found not to be copper oxide or TST but rather a combination of complex organic groups which are the polymer itself.

EXAMPLE 4: Cellulose-based polymer fiber preparation.

A rayon slurry or any cellulose slurry (waste of cotton and corn are very popular as a source of cellulose) is mixed with a plasticizer as is known in the industry of the production of these types of fibers. Normally the process involves a number of chemical steps that involve the breaking down of cellulose to very fine mulch of individual cells, adding a plasticizer, and then exposing the slurry to a solidifying process.

A powder made up of a combination of the two metal oxides, including copper oxide and tetrasilver tetroxide, was prepared. The metal powders were thoroughly mixed together and ground down to a particulate size of preferably under 5 μπι.

The powder was then added to the cellulose based slurry in a ratio of up to 3% wt. of the powder to the total weight of the slurry. The powder was added exactly at the same time the slurry is being passed through the holes of the spinneret so that the exposure to the acid in the final step of the process is limited to a few seconds as is common in the way these fibers are made.

The resulting slurry was solidified such that the metal oxide particles are homogeneously impregnated throughout the fiber.

EXAMPLE 5: Woven fabric preparation.

The system for preparation of woven fabrics from staple fibers follows the standard method as is common in the industry. After the staple fibers were prepared and were in bale form, they were put through a carder. The carder is a large cylinder with teeth which straightens out the fibers and makes them parallel to one another. The parallel fibers were formed into a very light web. The web was then twisted to form a tow. The tow was then more tightly spun to form the yarns. The thickness of the yarns is a function of how tightly the yarns were pulled and twisted. The yarns were then woven as is standard to the industry.

Figure 3 represents a SEM micrograph of a woven fabric comprising staple fibers comprising copper oxide powder and tetrasilver tetroxide powder incorporated therein.

EXAMPLE 6: Non- woven fabric preparation

Fibers in a non-woven fabric were extruded in a row with a few thousand spinneret holes through which the slurry was run. The slurry solidified upon exposure to the air but immediately after the extrusion the newly formed fibers were exposed to high pressure streams of air which cause the fibers to intermingle forming a sheath. The weight of the fabric is a function of the speed of the extrusion. The faster the extrusion, the lighter the fabric.

Figure 4 represents a SEM micrograph of a non-woven (spun-bond) fabric comprising staple fibers comprising copper oxide powder and tetrasilver tetroxide powder incorporated therein.

EXAMPLE 7: Protective mask fabrication

Fabrication of a surgical mask:

Surgical masks are made from between 2 and 5 layers of fabric. The layers of fabric are placed on a cutting table. The fabrics are cut in 20 cm X 20 cm squares. The layers of fabric are then placed in a pleating machine that puts between 3 and 6 pleats in the fabric and reduces the size of the original square to around 20 cm in length and 15 cm in width. This new 15 X 20 square is then sewn along all the edges. A rubber banding is added to the sides so that the mask can be fixed on the face.

Fabrication of a respirator:

Respirator masks are made on fully automated machinery. The fabrics are kept on rolls and the roll width is set at about 25 cm. All the layers, which are the spun bond layers (usually one inside and one outside) as well as a polyester shaper layer and the 3 melt blown layers are aligned in such a way that all layers meet at the front end of a molding machine. The layers are pressed into the hot mold press. The heat is enough to mold the fabric but not melt the fabric. The excess material around the now molded layers is removed.

EXAMPLE 8: Antimicrobial properties of the fibers comprising the combination of metal oxides.

100 μΐ aliquots of freshly prepared HIV-1 were incubated on top of the fibers produced according to the procedure described in Example 3, with varying amounts and ratios of copper oxide and tetrasilver tetroxide, as presented in Table 1. The incubation was performed for 30 minutes at 37°C. Then 10 μΐ of each incubated virus solution were added to MT-2 cells (human lymphocyte cell line) cultured in 1 ml neutral medium. The cells were then incubated for 5 days in a moist incubator at 37°C and the virus proliferation was determined by measuring the amount of p24 (HIV-1 capsid protein) in the supernatant with a commercial ELISA (enzyme linked immunesorbent assay) kit. The results show the average of duplicate experiments. As control for possible cytotoxicity of the Ag₄0₄ in combination with copper oxide to the cells, similar experiments were carried out as above. The fibers were incubated with 100 μΐ of standard/control medium that did not contain HIV-1. No cytotoxicity was observed.

Table 1 summarizes the evaluation of the ability of the fibers containing a combination of Ag₄0₄ and copper oxide, to inhibit HIV-1 proliferation in tissue culture, as compared to the fibers, containing copper oxide or tetrasilver tetroxide alone and to fibers, which do not contain metal oxides.

Table 1: Anti-viral efficacy test results.

EXAMPLE 9: Proliferation inhibition testing on woven polymer fabrics using AATCC Test Method 100-2004

The current experiment imitates a situation in which the fabric is worn in close proximity by a person. The human body acts as a reservoir and constantly supplies moisture, heat, and nutrients to microorganisms residing on the fabric via perspiration. Therefore, the incubation of bacteria on the fabric was carried out in 37 °C and with nutrients, as per AATCC Test Method 100-2004. Two types of samples were prepared. One type (regular copper oxide fabrics) included fabrics containing 3% wt. copper oxide in a polyester fiber. Another type (accelerated copper oxide fabrics) contained 2.4% wt. copper oxide + TST, of which copper oxide constituted 99.5% wt. and TST constituted 0.5% wt. in the same size polyester fiber as the fiber above.

All fabrics were sterilized prior to use via submergence in ethanol 70% for 10 minutes, followed by overnight drying in a sterile environment. Bacteria (E.coli) were grown overnight in a LB medium (10% tryptone 5% yeast extract, 10% NaCl (wt.%)) and diluted to approximately 10⁵ CFU/ml with a fresh autoclaved LB medium. The treated fabrics and the controls were then soaked with 1ml of the bacteria containing medium, placed in a closed sterile jar and incubated at 37 °C for the specified times.

Bacteria were extracted from the fabrics using fresh LB medium and then 200μ1 were seeded on LB-agar petri dishes overnight to allow the growth of colonies.

The effective reduction of the population of bacteria on each fabric was compared to its own control untreated fabric of the same material weave and size. Each experiment was done in duplicate, and averaged. The test results are presented in Tables 2-4. Table 2: Effective reduction of the population of bacteria by applying fabrics comprising a single oxidation state oxide or a combination of a mixed oxidation state oxide and a single oxidation state oxide measured at the time eriod of 0 - 40 min

Table 3: Effective reduction of the population of bacteria by applying fabrics comprising a single oxidation state oxide or a combination of a mixed oxidation state oxide and a single oxidation state oxide measured at the time period of 0 - 180 min

Table 4: Effective reduction of the population of bacteria by applying fabrics comprising a combination of a mixed oxidation state oxide and a single oxidation state oxide measured at

The bacteria proliferation inhibiting properties of the tested fabrics are also presented in Figures 5A-5C and 6A-6B.

The results show that the fabric treated with copper oxide and TST is more effective in inhibition of bacterial growth as compared to copper oxide alone, especially in the longer timescales of higher than 180 min.

EXAMPLE 10: Proliferation inhibition testing and air permeability testing of non-woven polymer fabrics

All tests were conducted using AATCC Test Method 100. This is a quantitative test which monitors the kill rate of the bacteria.

Two materials were tested: one fabric contained copper oxide and tetrasilver tetroxide and the second fabric did not contain the metal oxide powders and served as a control. Both fabrics were put in an autoclave for a number of hours to assure that they are free of microbes. In the test a fixed amount of serum containing a known amount of the targeted bacteria was placed on each fabric. Each fabric was then placed in an incubator for a fixed amount of time (generally 2 hours) at 37°C and 70% relative humidity.

The two fabrics were then removed from the incubator and each is dipped into a separate receptacle containing a sterile serum so that all bacteria on the fabric now remain in the serum and are no longer on the fabric.

A sample was then taken from each vial and cultured in a Petri dish. If the fabric has performed its antimicrobial activity then no colonies of bacteria or very few colonies of bacteria should be found. Allowing for proliferation time, the control should demonstrate no less than 3 times more bacteria than the amount in the original serum sample.

Results of the proliferation inhibition test are presented in Figure 7B. It can be clearly seen that the killing rate of the bacteria of the SMS material, wherein the spun-bond layer comprises the combination of copper oxide and tetrasilver tetroxide was considerably higher than that of the control SMS material, which did not include metal oxide powders and also higher than that of the SMS material including copper oxide alone.

The air permeability test was performed on the 8 g/cm² SMS material prepared according to the procedure described in Example 6, wherein the melt-blown fabric does not include the metal oxide powders. The test was performed on a single SMS array and on 2, 3, 16, 24 and 36 SMS arrays. Table 5 shows the results of the air permeation test.

Table 5: Air permeation and mean pore size of the SMS fabric comprising a combination of a mixed oxidation state oxide and a single oxidation state oxide

The common N95 masks include 3 melt-blown layers (not SMS), wherein the surface density of each layer is 30 g/m². Air permeability of said 3 melt-blown layers was found to be 151 L/m³ and the mean pore size was 9 μπι. It can therefore be concluded that air permeability of the material of the present invention including 16 SMS arrays, wherein the spun-bond fabrics comprise the synergistic combination of metal oxides, was about 3-times higher than that of the conventional protective mask filter material. Accordingly, materials of the present invention not only provide enhanced antibacterial activity, but are also highly air-permeable, thereby increasing wearer comfort.

EXAMPLE 11: Experimental methods

Detection of the mixed oxidation state oxide in the polymer material

A portion of textiles or fibers is put in an oven and brought to a temperature which allows the polymer to be carbonized to dust, but which is below the melting temperature of the metal oxides. The dust is then placed in an X-Ray Diffraction system which identifies crystalline structure of a crystal and as such can detect the presence of the metal oxides powders in the sample, which are present in addition to the carbon dust.

Measurement of the fabric mean pore size

As the fabrics are created, whether woven, knit, or non-woven, there is a natural space that forms between the fibers. The space will vary from 0.5 microns to 20 microns depending on the fiber or yarn size and how thick the sheath is. In order to reduce the pore size the fabrics are layered to reduce the average pore size as one fabric blocks the pores of the other. The ultimate size of the visible holes are measured through the passage of a light through the fabric. The more layers there are in the fabric, the smaller are the pores on the top surface.

Measurement of the air-permeability of the fabric

In this test a specific amount of air is pushed at a consistent pressure through a tube over which the fabrics is placed. The amount of the measured air is then timed to see how long it takes for the amount of air to arrive at the other side of the fabric.

While the present invention has been particularly described, persons skilled in the art will appreciate that many variations and modifications can be made. Therefore, the invention is not to be construed as restricted to the particularly described embodiments, rather the scope, spirit and concept of the invention will be more readily understood by reference to the claims which follow.

Claims

1. A fabric material having antimicrobial properties, said material comprising a polymer having incorporated therein a synergistic combination of at least two metal oxide powders, comprising a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, the powders being incorporated substantially uniformly within said fabric material, and wherein the ions of the metal oxides are in ionic contact upon exposure of said fabric material to moisture.

2. The fabric material according to claim 1, being in a form selected from the group consisting of a woven material, a non-woven material and combinations thereof.

3. The fabric material according to claim 2, being in a form of a non- woven fabric, selected from the group consisting of a spun bond fabric, melt blown fabric and combinations thereof.

4. The fabric material according to claim 3, comprising at least one layer of a melt blown fabric.

5. The fabric material according to claim 3, comprising at least one layer of a spun bond fabric.

6. The fabric material according to any one of claims 4 or 5, wherein the at least one layer has a thickness of from about 5 μπι to about 80 μιη.

7. The fabric material according to any one of claims 4 to 6, wherein the at least one layer has a surface density of from about 5 g/m² to about 70 g/m².

8. The fabric material according to any one of claims 4 to 7, wherein the at least one layer has a mean pore size of at least about 30 μπι.

9. The fabric material according to any one of claims 4 to 8, comprising between 1 to 90 layers.

10. The fabric material according to claim 3, comprising an spun bond-melt blown-spun bond (SMS) array comprising a layer of a melt blown fabric disposed between two layers of a spun bond fabric.

11. The fabric material according to claim 10, wherein the SMS array has a thickness of from about 5 μπι to about 90 μπι.

12. The fabric material according to any one of claims 10 or 11 , wherein the SMS array has a surface density of from about 5 g/m² to about 70 g/m².

13. The fabric material according to any one of claims 10 to 12, wherein the SMS array has a mean pore size of at least about 30 μπι.

14. The fabric material according to any one of claims 10 to 13, comprising from 1 to 90 SMS arrays.

15. The fabric material according to any one of claims 10 to 14, wherein the spun bond fiber comprises the synergistic combination of the at least two metal oxide powders incorporated therein.

16. The fabric material according to any one of claims 10 to 14, wherein the melt blown fiber comprises the synergistic combination of the at least two metal oxide powders incorporated therein.

17. The fabric material according to claim 2, being in a form of a woven fabric.

18. The fabric material according to claim 17, wherein the woven fabric has a surface density of from about 5 g/m² to about 70 g/m² and a mean pore size of from about 20 μπι to about 60 μπι.

19. The fabric material according to any one of claims 1 to 18, wherein the polymer is selected from the group consisting of polyalkene, polyester, polyamide, polyaramide, cellulose-based polymer, and combinations thereof.

20. The fabric material according to claim 19, wherein the polyalkene is selected from the group consisting of polypropylene, polyethylene and combinations thereof.

21. The fabric material according to any one of claims 3 to 16, wherein the spun bond fiber, the melt blown fiber or a combination thereof comprises polypropylene.

22. The fabric material according to any one of claims 1 to 21 , wherein the combined weight of the at least two metal oxide powders constitutes from about 0.05% wt. to about 5% wt. of the total weight of the material.

23. The fabric material according to any one of claims 1 to 22, wherein the mixed oxidation state oxide is selected from the group consisting of tetrasilver tetroxide (AgztOzt), Ag₃0₄, Ag₂0₂, tetracopper tetroxide (CU₄O₄), Cu (Ι,ΙΙΙ) oxide, Cu (11,111) oxide and combinations thereof.

24. The fabric material according to any one of claims 1 to 23, wherein the single oxidation state oxide is selected from the group consisting of copper oxide, silver oxide, zinc oxide and combinations thereof.

25. The fabric material according to any one of claims 1 to 24, wherein the synergistic combination of the at least two metal oxide powders comprises copper oxide and tetrasilver tetroxide.

26. The fabric material according to any one of claims 1 to 25, wherein the mixed oxidation state oxide constitutes up to about 15% wt. of the total weight of the synergistic combination of the at least two metal oxide powders and wherein the mixed oxidation state oxide is present in the synergistic combination in a detectable amount.

27. The fabric material according to any one of claims 1 to 26, wherein the metal oxide powders have substantially different specific gravities and substantially similar bulk densities.

28. The fabric material according to claim 27, wherein the metal oxide powders having the substantially similar bulk densities comprise particles which mean particle size is inversely proportional to the specific gravity thereof.

29. The fabric material according to claim 28, wherein the metal oxide powders having the substantially similar bulk densities comprise particles which have substantially similar mean particles sizes and wherein said particles are coated with a coating, which thickness is proportional to the specific gravity of the metal oxide particles.

30. A protective mask comprising the fabric material according to any one of claims 1 to 29, wherein the fabric material comprises a maximal thickness of 3.2 mm, surface density of from about 5 to about 30 g/m², and an air permeability of from about 150 to about 6000

L/m³.

31. The protective mask according to claim 30, being in a form of a fold-flat surgical mask or a molded cup- shaped mask.

32. The protective mask according to any one of claims 30 or 31, for use in combating or inhibiting the activity of microbes or micro-organisms, selected from the group consisting of gram-positive bacteria, gram-negative bacteria, fungi and viruses.

33. A personal protective clothing set comprising the material according to any one of claims 1 to 16 and 19 to 29.

34. The personal protective clothing set according to claim 33, being in a form of a hospital garment, wherein the fabric material comprises a maximal thickness of 3.2 mm and surface density of from about 15 g/m² to about 40 g/m².

35. The personal protective clothing set according to claim 33, being in a form of a first responder suit, wherein the fabric material comprises a max thickness of 7.2 mm and surface density of about 50 g/m² to about 70 g/m².

36. The personal protective clothing set according to any one of claims 33 to 35, for use in combating or inhibiting the activity of microbes or micro-organisms, selected from the group consisting of gram-positive bacteria, gram-negative bacteria, fungi and viruses.

37. A method for the preparation of the antimicrobial fabric material according to any one of claims 1 to 29, the method comprising the steps of: a. mixing the at least two metal oxide powders with at least one polymer; and b. forming fibers from the obtained mixture,

38. The method according to claim 37, wherein forming of the fibers is performed by extrusion.

39. The method according to any one of claims 37 or 38, further comprising forming said fibers into a woven or non-woven fabric.

40. The method according to claim 39, wherein forming the fibers into a non- woven fabric comprises depositing the fibers on a collecting belt and bonding the fibers by applying heated rolls or hot needles.

41. The method according to any one of claims 37 to 40, comprising mixing the obtained fabric with an additional type of fabric.

42. The method according to any one of claims 37 to 41, comprising processing the at least two metal oxide powders to have substantially similar bulk densities prior to step a.