HK1242358B - Antimicrobial material comprising synergistic combinations of metal oxides - Google Patents

Description

Antimicrobial materials comprising synergistic combinations of metal oxides

Technical Field

The present invention relates to a material comprising a polymer having incorporated therein a synergistic combination of metal oxides, said material having antimicrobial properties.

Background Art

It is well known that crowded places such as hospitals, healthcare facilities, food processing plants, hotels, dormitories and public transportation have the potential to spread disease. Therefore, these places need to use products that are less prone to the proliferation of microorganisms and pathogens. As microorganisms evolve to become more pathogenic and drug-resistant, the need to keep bioburden levels under control continues to increase, and the need to develop more effective control methods is increasing.

The presence of microorganisms in the hospital environment on many hospital items and equipment can cause nosocomial infections (HAIs). Even with all current cleaning and disinfection solutions, HAIs still occur in 4.5% of hospitalized patients in the United States each year and result in an estimated 100,000 deaths, adding $35.7 to $45 billion in healthcare costs. Bacteria and other microorganisms can evade routine cleaning that does not provide long-term protection against microorganisms. What is needed is a fast-acting, continuous (non-intermittent) supplement to routine cleaning. It should also be inexpensive and not compromise effectiveness, as healthcare institutions are working on very tight budgets.

It has been previously shown that certain individual metal oxides, when exposed to moisture, release ions into the environment to which they are exposed. These ions are also known to have antimicrobial, antiviral, and antifungal properties (Borkow and Gabbay, FASEB J. 2004 Nov; 18(14): 1728-30), as well as anti-mite properties (Mumchuoglu, Gabbay, Borkow, International Journal of Pest Management, Vol. 54, No. 3, July-September 2008, 235-240).

U.S. Patent No. 6,124,221 discloses an article of clothing having antibacterial, antifungal and antiyeast properties, comprising at least one group of metallized textiles, the textiles comprising fibers selected from the group consisting of natural fibers, synthetic cellulose fibers, regenerated protein fibers, acrylic fibers, polyolefin fibers, polyurethane fibers, vinyl fibers and blends thereof, and having a coating comprising an antibacterial, antifungal and antiyeast effective amount of at least one copper oxidized cationic substance, wherein the coating is directly bonded to the fibers.

U.S. Patent No. 6,482,424 discloses a method for combating and preventing nosocomial infections comprising providing textile fabrics incorporating fibers coated with copper in oxidized cationic form to healthcare facilities for patient contact and care, wherein the textile fabrics effectively inactivate antibiotic-resistant strains of bacteria.

U.S. Patent No. 7,169,402 covers an antimicrobial and antiviral polymeric material comprising a polymer selected from the group consisting of polyamide, polyester, and polypropylene and a single antimicrobial and antiviral component consisting essentially of tiny water-insoluble copper oxide particles incorporated into the polymer, wherein a portion of the particles in the polymer are exposed and protrude from the surface of the material, and wherein the particles release Cu2 ⁺ when exposed to water or water vapor.

U.S. Patent Application Publication No. 2008/0193496 discloses a polymer masterbatch for preparing an antimicrobial, antifungal, and antiviral polymeric material comprising a slurry of a thermoplastic resin, an antimicrobial and antiviral agent consisting essentially of water-insoluble particles of ionic copper oxide, a polymeric wax, and an agent for occupying the charge of the ionic copper oxide.

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

Similar findings regarding the antimicrobial activity of metal oxides have been published for tetrasilver tetroxide as a mixed oxidation state compound, as cited in various publications and patents by Antelman.

Antelman, U.S. Pat. No. 6,645,531, discloses a pharmaceutical composition comprising a therapeutically effective amount of at least one electron-active compound or a pharmaceutically acceptable derivative thereof having at least two multivalent 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, Mn(II,III) oxide, and Pr(III,IV) oxide, and optionally Ag(I,III) oxide. Also provided is a method for stopping, reducing, or inhibiting the growth of at least one of bacteria, fungi, parasitic microorganisms, and viruses, the method comprising administering to a human subject a therapeutically effective amount of the at least one electroactive compound.

Antelman, US Patent No. 6,436,420, is directed to fibrous textile articles having enhanced antimicrobial properties prepared by depositing or interstitially precipitating tetrasilver tetroxide (Ag ₄ O ₄ ) crystals within the interstices of the fibers, yarns, and/or fabrics forming such articles.

There is an unmet need for cost-effective materials with improved antimicrobial and antiviral properties that can be beneficially used to combat or inhibit microbial activity and prevent or treat infection.

Summary of the Invention

The present invention relates to materials having antimicrobial properties and methods for preparing the same. The antimicrobial material comprises a polymer and a synergistic combination of at least two metal oxide powders incorporated into the polymer, the combination comprising a mixed oxidation state oxide and a single oxidation state oxide. The metal oxide powders are incorporated into the polymer such that upon hydration of the material, the ions of the two metal oxides are in ionic contact with each other.

The present invention is based, in part, on the surprising 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 particles provides a synergistic effect compared to the activity of each metal oxide alone. It was also surprisingly found that the mixed oxidation state oxide provides a synergistic antimicrobial effect even when added in an amount of less than 10 wt. % of the total weight of the combination.

Uniform incorporation of inorganic particles into a substrate, particularly a polymeric substrate, is challenged by particle agglomeration, chemical and physical interactions between the particles and the substrate, and, most importantly, differences in the specific gravity of the particulate material. However, certain embodiments of the present invention comprise materials of particulate metal oxides having substantially different specific gravities, typically characterized by a uniform distribution of the metal oxide powders throughout the polymer fibers. The present invention overcomes the problems associated with the use of different types of metal oxides by equalizing the bulk density of the metal oxide particles. Thus, according to certain embodiments, the materials of the present invention comprise metal oxide powders having substantially similar bulk densities even when having substantially different specific gravities. To compensate for the differences in specific gravity and achieve substantially similar bulk densities, the average particle size of the metal oxides can be reduced proportionally. Alternatively, the bulk densities of the metal oxides can be equalized by coating the powders with a coating having a thickness or weight proportional to the specific gravity of the metal oxide powders.

Thus, according to one aspect, the present invention provides a material having antimicrobial properties, the material comprising a polymer having incorporated therein a synergistic combination of at least two metal oxides, the combination comprising a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, the powders being substantially uniformly incorporated into the polymer, wherein the powders have substantially different specific gravities and substantially similar bulk densities, and wherein upon exposure of the material to moisture, ions of the metal oxides come into ionic contact. According to certain embodiments, the first and second metals are different.

In certain embodiments, the mixed oxidation state oxide is selected from tetrasilver tetroxide (Ag ₄ O ₄ ), Ag ₃ O ₄ , Ag ₂ O ₂ , tetracopper tetroxide (Cu ₄ O ₄ ), Cu(I, III) oxide, Cu(II, III) oxide, Cu ₄ O ₃ and combinations thereof. Each possibility represents an independent embodiment of the present invention. In other embodiments, the mixed oxidation state oxide is selected from tetrasilver tetroxide (Ag ₄ O ₄ ), Ag ₂ O ₂ , tetracopper tetroxide (Cu ₄ O ₄ ), Cu(I, III) oxide, Cu(II, III) oxide and combinations thereof. Each possibility represents an independent embodiment of the present invention. In certain embodiments, the single oxidation state oxide is selected from copper oxide, silver oxide, zinc oxide and combinations thereof. Each possibility represents an independent embodiment of the present invention. Copper oxide may be selected from cuprous oxide (Cu ₂ O), cupric oxide (CuO) and combinations thereof. Each possibility represents an independent embodiment of the present invention. In a specific embodiment, the combination of at least two metal oxides comprises copper oxide and tetrasilver tetroxide. In other specific embodiments, the copper oxide is cuprous oxide.

According to certain embodiments, the mixed oxidation state oxide comprises up to about 60 wt.% of the total weight of the synergistic combination of the at least two metal oxide powders. According to other embodiments, the mixed oxidation state oxide comprises up to about 15 wt.% of the total weight of the synergistic combination of the at least two metal oxide powders.

According to other embodiments, the mixed oxidation state oxide comprises from about 0.5 wt.% to about 15 wt.% of the total weight of the synergistic combination of the at least two metal oxide powders. According to other embodiments, the mixed oxidation state oxide comprises about 1 wt.% of the total weight of the synergistic combination of the at least two metal oxide powders.

According to certain embodiments, the mixed oxidation state oxide comprises from about 0.05 wt.% to about 15 wt.% of the total weight of the synergistic combination of the at least two metal oxide powders. According to other 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 other embodiments, the presence of the mixed oxidation state oxide in the material can be detected using X-ray diffraction spectroscopy (XRD), electron microscopy, electron spectroscopy, Raman spectroscopy, or electronic analytical methods. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the metal oxide is not exposed on the surface of the material. According to other embodiments, the powder is distributed in a generally uniform manner on the surface of the material. According to other embodiments, the metal oxide particles protrude from the surface of the material. In other embodiments, the metal oxide particles are attached to, deposited on, or embedded in the surface of the material.

According to certain embodiments, each of the metal oxide powders independently comprises particles having an average particle size of about 1 nanometer to about 10 microns. According to other embodiments, each of the metal oxide powders independently comprises particles having a particle size of about 10 nanometers to about 10 microns. According to other embodiments, each of the metal oxide powders independently comprises particles having a particle size of about 0.5 to about 1.5 microns.

According to certain embodiments, the metal oxide powders having substantially similar bulk density comprise particles having an average particle size that is inversely proportional to their specific gravity. According to other embodiments, the metal oxide powders having substantially similar bulk density comprise particles having substantially similar average particle size, and wherein the particles are coated with a coating. According to other embodiments, the thickness of the coating is proportional to the specific gravity of the metal oxide particles. In alternative embodiments, the weight of the coating is proportional to the specific gravity of the metal oxide powder. According to other embodiments, the coating comprises a polyester or polyolefin wax. The polyester or polyolefin wax may be selected from polypropylene wax, oxidized polyethylene wax, ethylene homopolymer wax, and combinations thereof. Each possibility represents a separate embodiment of the present invention.

According to other embodiments, the metal oxide powder comprises particles encapsulated in an encapsulating compound. The encapsulating compound may comprise a silicate, an acrylate, a cellulose, a derivative thereof, or a combination thereof. A non-limiting example of an acrylate is polymethyl methacrylate (PMMA). According to certain exemplary embodiments, the encapsulating agent is a silicate or polymethyl methacrylate (PMMA).

According to certain embodiments, the materials of the present invention further comprise a chelating agent or metal deactivator associated with the metal oxide powder. The metal deactivator can be selected from phenolic antioxidants, potassium iodide, potassium bromide, calcium stearate, zinc stearate, aluminum stearate, tertiary chain extenders, and combinations thereof. Each possibility represents a separate embodiment of the present invention.

According to other embodiments, the material of the present invention further comprises a surfactant associated with the metal oxide powder. The surfactant may include a sulfate, a sulfonate, a silicone, a silane, or a nonionic surfactant. Non-limiting examples of commercially available surfactants include Sigma Aldrich, Dow Corning, and Triton-X-100. The surfactant may also comprise a solvent, such as, but not limited to, methanol, methyl ethyl ketone, or toluene. According to certain embodiments, the material does not contain the surfactant.

According to certain embodiments, the material of the present invention comprises a polymer selected from a synthetic polymer, a naturally occurring polymer, or a combination thereof. Each possibility represents a separate embodiment of the present invention. According to certain embodiments, the synthetic polymer is selected from an organic polymer, an inorganic polymer, and a bioplastic. In other embodiments, the polymer is selected from a polyamide, a polyester, an acrylic polymer, a polyolefin, a polysiloxane, a nitrile, a polyvinyl acetate, a starch-based polymer, a cellulose-based polymer, dispersions, and mixtures thereof. According to certain currently preferred embodiments, the polymer is selected from a polyester, a polyolefin, and a polyamide. The polyolefin may be selected from a polypropylene, a polyethylene, and a combination thereof. Each possibility represents a separate embodiment of the present invention. According to a specific embodiment, the polymer is selected from a polyethylene, a polypropylene, acrylonitrile-butadiene-styrene (ABS), a polylactic acid (PLA), a polyglycolic acid (PGA), a lactic acid-glycolic acid copolymer (PLGA), a polybutyl acrylate (PBA), a polybutylene terephthalate (PBT), and a combination thereof. The polymer may be water-based or solvent-based.

According to certain embodiments, the material of the present invention is selected from an intermediate product, a semi-final product, or a final product.

In certain embodiments, the metal oxide powder is incorporated into the polymer via a masterbatch manufacturing process. Thus, according to certain embodiments, the intermediate product is a masterbatch.

According to certain embodiments, the semi-final product comprises a fiber, a yarn, a textile, a fabric, a film or a foil. Each possibility represents an independent embodiment of the present invention. The textile can be selected from woven fabrics, knitted fabrics, non-woven fabrics, needle-punched fabrics or felt. Each possibility represents an independent embodiment of the present invention. According to certain embodiments, the semi-final product is a fiber. The fiber can be a filament fiber or a staple fiber. According to certain embodiments, the metal oxide powder is substantially uniformly incorporated into the fiber. The fiber can be formed into a yarn, a textile or a fabric.

According to certain embodiments, the final product is a textile product or a non-woven polymeric article. According to certain embodiments, the yarn, textile or fabric is formed into the textile product.

According to other embodiments, the polymer is formed into a semi-final product or final product by extrusion, molding, casting, or 3D printing. Each possibility represents a separate embodiment of the present invention. According to certain embodiments, the textile product comprises an extruded polymer. According to other embodiments, the semi-final product comprises an extruded polymer. According to certain embodiments, the fiber comprises an extruded polymer. According to other embodiments, the non-woven polymer article comprises an extruded, molded, or cast polymer.

In certain embodiments, the combined weight of the at least two metal oxides comprises from about 0.25 wt.% to about 50 wt.% of the total weight of the material.

In certain embodiments, the material is in the form of a masterbatch. In other embodiments, the combined weight of the at least two metal oxides comprises from about 0.5% to about 50% by weight of the total weight of the masterbatch. In other embodiments, the combined weight of the at least two metal oxides comprises from about 20% to about 40% by weight of the total weight of the masterbatch.

In certain embodiments, the material is in the form of a fiber, yarn, textile, or fabric. In certain such embodiments, the combined weight of the at least two metal oxides comprises from about 0.5 wt.% to about 15 wt.% of the total weight of the material.

According to certain embodiments, the fibers are synthetic or semi-synthetic polymeric fibers. According to certain embodiments, the material further comprises natural fibers. Thus, in certain embodiments, the fibers are a blend of polymeric fibers and natural fibers.

According to other embodiments, the material comprises natural fibers in an amount up to about 85% by weight of the total weight of the material. In a specific embodiment, the material comprises natural fibers in an amount up to about 70% by weight of the total weight of the textile product. The natural fibers can be selected from the group consisting of cotton, silk, wool, flax, and combinations thereof. Each possibility represents a separate embodiment of the present invention. In a certain embodiment, the material comprises cotton.

According to certain embodiments, the material comprises a blend of polymeric fibers and natural fibers. In certain such embodiments, the combined weight of the at least two metal oxides comprises from about 0.25 wt.% to about 5 wt.% of the total weight of the material.

According to some embodiments, the material is in the form of textile products or non-woven polymer products.Every possibility has represented independent embodiment of the present invention.The textile products can be selected from clothing products, bedding textiles, laboratory or hospital textiles, medical textiles, comprise textiles or personal hygiene products used in bandages or sutures and interior.The limiting examples of the textile products comprises pillowcases, eye masks, gloves, socks, stockings, sleeves, shoe covers, slippers, underwear, industrial uniforms, sportswear, towels, kitchen cloths, lab coats, floor cloths, sheets, bedding, curtains, textile covers, hard surface covers, diapers, incontinence pads, feminine hygiene products, gauze pads, monolithic extruded films, bodysuits, transdermal patches, bandages, adhesive bandages, sutures, interior sheaths and textiles used.The non-woven polymer products can be selected from packaging or wrapping materials, laboratory equipment, hospital equipment, is preferably disposable hospital equipment, contraceptive device, agricultural products, capping and sanitary products for consumer goods. Non-limiting examples of the nonwoven polymeric article include food packaging, gloves, blood bags, catheters, ventilation tubes, feeding tubes, delivery tubes, mobile phone housings, pipes, toilet seats or toilet seat covers, kitchen sponges, work surface covers, and condoms. In certain embodiments, the material is in the form of a product selected from the group consisting of clothing articles, bedding textiles, laboratory or hospital textiles, laboratory equipment, hospital equipment, medical textiles including bandages or sutures and textiles for internal use, personal hygiene products, packaging or wrapping materials, closures for consumer products, food equipment, contraceptive devices, agricultural products, or sanitary products.

In certain embodiments, the present invention provides materials for combating or inhibiting the activity of microorganisms or microorganisms selected from gram-positive bacteria, gram-negative bacteria, fungi, parasites, molds, spores, yeasts, protozoa, algae, mites and viruses. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the material is used to combat healthcare associated infections, nosocomial infections, or a combination thereof.Each possibility represents a separate embodiment of the present invention.

Alternatively or in addition, the materials of the present invention can be used to treat or prevent atopic fungal, bacterial, and viral infections. The infection can be selected from athlete's foot, yeast infection, and staphylococcal infection. Each possibility represents a separate embodiment of the present invention. In other embodiments, the materials are used to treat or prevent surface viral infections. The infection can be selected from warts and herpes B. Each possibility represents a separate embodiment of the present invention.

In another aspect, the present invention provides a method for preparing a material having antimicrobial properties, the material comprising a polymer having incorporated therein a synergistic combination of at least two metal oxide powders, the combination comprising a mixed oxidation state oxide of a first metal and a single oxidation state oxide of a second metal, the powders being substantially uniformly incorporated into the polymer, wherein the powders have substantially different specific gravities and substantially similar bulk densities, and wherein upon exposure of the material to moisture, ions of the metal oxides come into ionic contact, the method comprising the steps of:

a. processing the at least two metal oxide powders to obtain substantially similar bulk density; and

b. Mixing the powder with at least one polymer.

According to certain embodiments, step a. comprises processing the metal oxide powder to obtain particles having an average particle size inversely proportional to its specific gravity. In certain embodiments, the processing comprises grinding.

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

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

According to other embodiments, step b. comprises producing a masterbatch comprising the metal oxide powder and a carrier polymer. According to certain embodiments, the at least one polymer comprises the carrier polymer. According to preferred embodiments, the masterbatch is homogeneous. The masterbatch can be formed into pellets. Alternatively, the masterbatch can be formed into granules.

In certain embodiments, step b. further comprises adding the masterbatch to the polymer slurry. In other embodiments, the polymer slurry comprises the same polymer as the carrier polymer. In other embodiments, the polymer slurry comprises a polymer that is chemically compatible with the carrier polymer.

According to certain embodiments, the method further comprises step c., comprising forming a film, foil, fiber, yarn, fiber, textile, textile product or non-woven polymer article from the obtained mixture. Each possibility represents an independent embodiment of the present invention.

According to certain specific embodiments, the method further comprises a step c., comprising forming a film, foil, fiber, yarn, fiber or textile comprising the powder from the obtained mixture. Each possibility represents an independent embodiment of the present invention. According to other specific embodiments, the method further comprises a step c., comprising forming a textile product or a non-woven polymer article comprising the powder from the obtained mixture. Each possibility represents an independent embodiment of the present invention.

In certain embodiments, step c. comprises extrusion, molding, casting, or 3D printing. In certain exemplary embodiments, step c. comprises extrusion. In other embodiments, extrusion comprises spinning through a spinneret. In preferred embodiments, the material is uniformly extruded. In other embodiments, step c. comprises molding.

In certain embodiments, step c. comprises forming polymeric fibers from the mixture obtained in step b. In certain embodiments, the method further comprises blending the polymeric fibers with natural fibers. In certain embodiments, the method comprises forming the fibers into yarn, textile, fabric, or textile product.

Other 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 present invention, are given for illustrative purposes only, as various changes and modifications within the spirit and scope of the present invention will become apparent to those skilled in the art from the detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1A : SEM micrograph of polyester staple fibers containing copper oxide and tetrasilver tetroxide with protruding particles prepared by a masterbatch preparation method at 1000X magnification.

FIG. 1B : SEM micrograph of polyester staple fibers containing copper oxide and tetrasilver tetroxide with protruding particles prepared by a masterbatch preparation method at 4000X magnification.

FIG1C : SEM micrograph of a cross section of the fiber of FIG1A and IB at 4000X magnification showing copper oxide and tetrasilver tetroxide and protruding particles.

FIG2A : SEM micrograph of cotton fibers impregnated with tetrasilver tetroxide with sonochemically nanodeposited copper oxide at 5000X magnification.

FIG2B : SEM micrograph of cotton fibers impregnated with tetrasilver tetroxide with sonochemically nanodeposited copper oxide at 20,000X magnification.

Figure 3: SEM micrograph of polyester staple fibers impregnated with copper oxide and tetrasilver tetroxide by ultrasound-assisted method at 20,000X magnification, where the particles are encapsulated within the fibers.

Figure 4: Inhibition of bacterial proliferation of an extruded polypropylene film comprising copper oxide and tetrasilver tetroxide (dashed line) compared to a control of an untreated polypropylene film of the same material and dimensions (solid line).

Figures 5A-5C show bacterial growth inhibition on polymer fabrics containing copper oxide and tetrasilver tetroxide, where solid colored bars represent polymer fabrics containing a combination of copper oxide and TST, and confetti-patterned bars represent controls—untreated fabrics of the same material and dimensions. Figure 5A shows bacterial growth inhibition between 0 and 40 minutes after the fabric was exposed to the bacteria-containing medium; Figure 5B shows bacterial growth inhibition between 0 and 180 minutes after the fabric was exposed to the bacteria-containing medium; and Figure 5C shows bacterial growth inhibition between 0 and 300 minutes after the fabric was exposed to the bacteria-containing medium.

Figures 6A-6B show bacterial growth inhibition on a copper oxide-containing polymer fabric, where the bars in a grid pattern represent the copper oxide-containing polymer fabric, and the bars in a dot pattern represent the control—an untreated fabric of the same material and dimensions. Figure 6A shows bacterial growth inhibition between 0 and 40 minutes after the fabric was exposed to a culture medium containing bacteria. Figure 6B shows bacterial growth inhibition between 0 and 180 minutes after the fabric was exposed to a culture medium containing bacteria.

Figure 7: Inhibition of bacterial proliferation of cotton-blended polymer fabrics containing copper oxide and tetrasilver tetroxide, and copper oxide alone, wherein the striped pattern bars represent the untreated control (70% cotton/30% polyester fiber), the checkerboard pattern bars represent the 70% cotton/30% polyester fiber containing copper oxide, the grid pattern bars represent the 50% cotton/50% polyester fiber containing the combination of copper oxide and TST, and the solid colored bars represent the 70% cotton/30% polyester fiber containing the combination of copper oxide and TST.

Detailed description

The present invention relates to materials having improved antimicrobial properties, including enhanced antibacterial, antiviral and antiparasitic activity, and to methods of making the same. The antimicrobial material of the present invention comprises a polymer and a synergistic combination of at least two metal oxide powders uniformly incorporated into the polymer.

As used herein, the term "antimicrobial" refers to an inhibitory, microbicidal or microbial effect against microorganisms, pathogens and microorganisms, including but not limited to enveloped viruses, non-enveloped viruses, Gram-positive bacteria, Gram-negative bacteria, fungi, parasites, molds, yeasts, spores, algae, protozoa, mites and dust mites, and the resulting deodorizing properties.

According to certain embodiments, the material of the present invention is selected from intermediate products such as, but not limited to, masterbatches, semi-final products such as fibers, yarns, textiles, fabrics, films or foils, or final products including, in particular, textile products or non-woven polymeric articles.

The synergistic combination of 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 powders have substantially similar bulk densities, and wherein ions of the metal oxides are in ionic contact upon hydration or exposure of the materials to residual moisture.

As used herein, the term "ionically accessible" refers to the ability of ions of each metal oxide powder incorporated into the polymer to flow toward a common aqueous reservoir upon exposure to the reservoir.

Synergistic combination of two metal oxides

It has surprisingly been found that in order to enhance the 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 be bound by theory or mechanism of action, in order to provide induced biocidal activity, the metal oxide particles should be mixed together such that the particles of each oxide are exposed to the same moisture reservoir, thereby enabling ions to diffuse from each metal oxide compound to the common moisture reservoir.

The synergistic combination of the two metal oxides is a non-naturally occurring biologically active combination, 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. According to certain embodiments, the non-naturally occurring metal oxide combination applied to the polymeric substrate exhibits greater ion activity than the individual naturally occurring compounds. Without wishing to be limited by theory of action or mechanism, the increased ion activity results in a greater microbicidal effect when compared to an equal amount of the naturally occurring metal oxide compound under similar conditions.

As defined herein, the term "synergistic combination" refers to a combination of at least two metal oxides that provides a higher antimicrobial efficacy than an equal amount of each metal oxide alone. The higher antimicrobial efficacy may be associated with an accelerated rate of killing bacteria or microorganisms.

The synergistic combination applied to the 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, which have been found to be biologically active on their own and to be synergistic, providing surprisingly accelerated microbial death compared to the same single and mixed oxidation state metal oxides alone or combined within a naturally occurring single oxidation state group.

As used herein, the term "mixed oxidation state" refers to atoms, ions or molecules in which electrons are delocalized to a certain extent and shared between atoms through various different electronic transition mechanisms, resulting in conjugated bonds that affect the physicochemical properties of the material. In the mixed oxidation state, electronic transitions form a superposition between two single oxidation states. This can be represented as any metal with more than one coexisting single oxidation state, as in the formula X(Y,Z), where X is a metal element and Y and Z are oxidation states, where Y≠Z. The mixed oxidation state oxide can be a compound in which metal ions are in different oxidation states (i.e., X(Y,Z)).

According to certain embodiments, the mixed oxidation state oxides useful in the materials of the present invention are selected from tetrasilver tetroxide (TST) - Ag ₄ O ₄ (Ag I, III), Ag ₃ O ₄ , Ag ₂ O ₂ , tetracopper tetroxide - Cu ₄ O ₄ (Cu I, III), Cu ₄ O ₃ , Cu(I, II), Cu(II, III), Co(II, III), Pr(III, IV), Bi(III, V), Fe(II, III), and Mn(II, III) oxides, and combinations thereof. Each possibility represents a separate embodiment of the present invention. In certain embodiments, the material comprises a mixed oxidation state oxide selected from tetrasilver tetroxide, tetracopper tetroxide, and combinations thereof.

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

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

As used herein, the term "copper oxide" refers to any or both of the various oxidation states of copper oxide: a first, major single oxidation state, cuprous oxide (( _Cu2O ), also known as copper(I) oxide); or a second, higher single oxidation state, cupric oxide ((CuO), also known as copper(II) oxide), either alone or in varying proportions.

As used herein, the term "silver oxide" refers to the various oxidation states of silver oxide: the first, principal single oxidation state, _Ag2O (also known as silver(I) oxide); or the second, higher single oxidation state, AgO (also known as silver(II) oxide); or the third, highest single oxidation state _{, Ag2O3} , either alone or in any varying ratios of these three naturally occurring oxidation states.

As used herein, the term "zinc oxide" refers to the primary oxidation state of zinc oxide, _ZnO2 .

According to certain embodiments, the copper oxide is selected from _Cu2O , CuO, and combinations thereof. According to other embodiments, the silver oxide is selected from _Ag2O , AgO, _{Ag2O3 ,} and combinations thereof. Each possibility represents a separate embodiment of the present invention.

In certain embodiments, the material comprises a single oxidation state oxide selected from copper oxide, silver oxide, and combinations thereof. In other embodiments, the single oxidation state oxide is copper oxide. In other embodiments, the material comprises a single oxidation state oxide selected from Cu ₂ O, CuO, and combinations thereof. Each possibility represents a separate embodiment of the present invention. In certain embodiments, the copper oxide is Cu ₂ O.

According to certain embodiments, metal oxides useful in the materials of the present invention are selected from copper oxide, tetracopper tetroxide, silver oxide, tetrasilver tetroxide, zinc oxide, and combinations thereof. According to other embodiments, the metal oxides are selected from Cu ₂ O, CuO, Cu ₄ O ₄ , Ag ₂ O, AgO, Ag ₂ O ₃ , Ag ₄ O ₄ , ZnO ₂ , and combinations thereof. In particular embodiments, the material comprises at least two metal oxides selected from copper oxide, tetrasilver tetroxide, tetracopper tetroxide, and combinations thereof. In currently preferred embodiments, the single oxidation state oxide is copper oxide, and the mixed oxidation state oxide is tetrasilver tetroxide. In other 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 a synergistic antimicrobial effect. While the acceleration of the antimicrobial effect of naturally occurring copper oxides, including mixtures of cupric oxide and cuprous oxide, is disclosed in, for example, U.S. Patent No. 7,169,402, the present invention provides for the first time non-naturally occurring metal oxide combinations, particularly combinations comprising single oxidation state oxides in combination with tetracopper tetroxide or tetrasilver tetroxide, characterized by synergistic antimicrobial growth properties. Considering the biocidal activity of combinations of copper oxide and proven silver compounds tested by the present inventors and demonstrated in the experimental section, the synergistic effect of compositions comprising a mixture of two different metal oxides, at least one of which is a mixed oxidation state oxide, is even more surprising. Adding a silver compound to _Cu₂O does not increase its biocidal rate, and no synergistic acceleration is observed. The antimicrobial properties of the single oxidation state metal oxides are only enhanced when the mixed oxidation state form of silver ( _Ag₄O₄ ) is combined with a single oxidation state metal oxide comprising _copper oxide. The antimicrobial activity of the combination of metal oxides is also enhanced compared to the activity of the mixed oxidation state metals alone. Without wishing to be bound by theory or mechanism of action, the measured synergistic effect of these combinations can be attributed to intervalent charge transfer between metal ions having different oxidation states. Exposure of a combination of at least two metal oxides, including a mixed oxidation state oxide and a single oxidation state oxide, to a common moisture reservoir establishes ionic contact between the metal oxides and allows ions to be released from each metal oxide to the common moisture reservoir, thereby providing an acceleration in the rate of microbial mortality.

According to other embodiments, the materials of the present invention comprise a synergistic combination of at least two metal oxides consistent with the principles of the present invention, wherein each of the metal oxides may be present in the combination in a weight percentage 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 present invention.

Surprisingly, it has been found that incorporating 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 an amount less than 10% by weight of the total weight of the combination of metal oxides, is sufficient to result in an acceleration of the antimicrobial activity of the polymer compared to each polymer comprising the mixed oxidation state oxide and the single oxidation state oxide alone. This finding is even more surprising because the total weight of the mixed oxidation state oxide in the polymer comprising the combination of metal oxide powders is 10 times lower than in the polymer comprising the mixed oxidation state oxide alone.

Thus, according to certain embodiments, the mixed oxidation state oxide comprises from about 1 wt.% to about 20 wt.% of the total weight of the combination of the two metal oxides. According to other embodiments, the mixed oxidation state oxide comprises from about 5 wt.% to about 15 wt.% of the total weight of the combination of the two metal oxides. According to other embodiments, the mixed oxidation state oxide comprises about 10 wt.% of the total weight of the combination of the two metal oxides.

According to other embodiments, the mixed oxidation state oxide comprises up to about 60 wt.%, 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 present invention.

It has also been discovered that polymers containing as little as 3 wt.% of the mixed oxidation state oxide in the metal oxide combination have enhanced biocidal activity compared to polymers containing the single oxidation state oxide alone at the same weight percentage of the metal oxide in the polymer as the weight percentage of the metal oxide in the metal oxide combination. It has also been surprisingly discovered that materials containing the combination of the two metal oxides have enhanced antimicrobial activity compared to the biocidal activity of the single oxidation state oxides even when the combination contains as little as 0.5 wt.% of the mixed oxidation state oxide. Thus, the mixed oxidation state oxide can be beneficially used in the material at relatively low concentrations compared to the single oxidation state oxides, thereby increasing the commercial viability of the material.

According to certain embodiments, the mixed oxidation state oxide comprises from about 0.05 wt.% to about 99.5 wt.% of the total weight of the combination of the two metal oxides, such as from about 0.05 wt.% to about 90 wt.%, from about 0.05 wt.% to about 80 wt.%, from about 0.05 wt.% to about 70 wt.%, from about 0.05 wt.% to about 60 wt.%, from about 0.05 wt.% to about 50 wt.%, from about 0.05 wt.% to about 40 wt.%, from about 0.05 wt.% to about 30 wt.%, from about 0.05 wt.% to about 20 wt.%, or from about 0.05 wt.% 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 other embodiments, the mixed oxidation state oxide comprises from about 0.05 wt.% to about 15 wt.% of the total weight of the combination of the two metal oxides, such as from about 0.1 wt.% to about 15 wt.%, from about 0.5 wt.% to about 15 wt.%, from about 1 wt.% to about 5 wt.%, from about 0.5 wt.% to about 5 wt.%, or from about 0.1 wt.% to about 3 wt.% of the total weight of the combination of the two metal oxides. Each possibility represents a separate embodiment of the present invention.

According to certain embodiments, the mixed oxidation state oxide comprises about 1 wt.% of the total weight of the combination of the two metal oxides. According to other certain embodiments, the mixed oxidation state oxide comprises about 0.5 wt.% of the total weight of the combination of the two metal oxides. According to other certain embodiments, the mixed oxidation state oxide comprises about 0.1 wt.% of the total weight of the combination of the two metal oxides. According to other certain embodiments, the mixed oxidation state oxide comprises about 0.05 wt.% of the total weight of the combination of the two metal oxides. According to certain embodiments, the antimicrobial effect of the combination of the two metal oxides is synergistic.

According to certain embodiments, the mixed oxidation state oxide is present in a detectable amount in the synergistic combination of the metal oxide powders. The presence of the mixed oxidation state oxide in the synergistic mixture can be detected by X-ray diffraction spectroscopy (XRD), electron microscopy, electron spectroscopy, Raman spectroscopy or electronic analysis methods. Electron spectroscopy includes, in particular, X-ray photoelectron spectroscopy (XPS), electron spectroscopy for chemical analysis (ESCA) and Auger electron spectroscopy (AES). A non-limiting example of an electron microscopy method suitable for detecting mixed oxidation state oxides is scanning electron microscopy (SEM), which is optionally coupled with X-ray energy dispersive spectroscopy (EDS). According to certain embodiments, the presence of the mixed oxidation state oxide is detected by XRD.

Metal oxide powder

The copper oxide useful in the materials of the present invention can be any commercially available copper oxide powder having a purity level of not less than 97 wt.%. In certain exemplary embodiments, the powder is purchased from SCM Inc. (North Carolina, USA). Since suppliers of such powders are very common, manufacturing such powders is not economically feasible. The zinc oxide useful in the materials of the present invention can be any commercially available zinc oxide powder having a recommended purity level of not less than 98 wt.%, which is readily available. However, since tetrasilver tetroxide and/or tetracopper tetroxide are difficult to obtain, it is necessary to synthesize the specific substances as described below.

According to certain embodiments, commercially available metal oxide powders have a particle size of about 10 to about 20 microns. The metal oxide powders can be ground to a particle size of about 1 nanometer to about 10 microns. Thus, the metal oxide particles in the materials of the present invention can have a particle size of about 1 nanometer to about 10 microns. According to certain embodiments, the particle size is about 1 to 10 microns. According to other embodiments, the particle size is about 5 to about 8 microns. According to other embodiments, the particle size is about 0.1 to about 0.5 microns. According to other embodiments, the particle size is about 0.25 to about 0.35 microns. According to certain embodiments, the metal oxide powder contains agglomerates no larger than 20 microns. According to other embodiments, the metal oxide powder contains agglomerates no larger than 10 microns. In other embodiments, the materials of the present invention do not contain metal oxide particle agglomerates.

polymer

As used herein, the term "polymer" or "polymeric" refers to a material composed of repeating structural units called monomers. Polymers can be homogeneous or heterogeneous in their form, hydrophilic or hydrophobic, natural, synthetic, mixed synthetic or bioplastic. Non-limiting examples of polymers suitable for incorporation into the metal oxide powder include, among others, polyamides, polyesters, acrylic polymers, isotactic compounds including but not limited to polypropylene, polyethylene, polyolefins, acrylic compounds, polyolefins, silicones and nitriles, cellulose-based polymers or mixtures of different cellulose materials, converted cellulose mixed with plasticizers such as but not limited to rayon and viscose, starch-based polymers and acetates, petroleum derivatives and petroleum gels, synthetic and natural fats, polyurethanes, natural latex, and mixtures and combinations thereof. Each possibility represents an independent embodiment of the present invention.

According to certain embodiments, the polymer is a synthetic polymer, including organic polymers, inorganic polymers and bioplastics. According to certain embodiments, the polymer is selected from polyamides, polyesters, acrylic polymers, polyolefins, polysiloxanes, nitriles, polyvinyl acetates, cellulose-based polymers, starch-based polymers, derivatives thereof, dispersions thereof and combinations thereof. Each possibility represents an independent embodiment of the present invention. Non-limiting examples of cellulose-based polymers are viscose or rayon. According to certain embodiments, the polymer is selected from polyamides, polyesters, acrylic polymers, polyolefins and combinations thereof. According to other embodiments, the polymer is selected from polyamides, polyolefins, polyurethanes, polyesters and combinations thereof. Each possibility represents an independent embodiment of the present invention. According to specific embodiments, the polymer is selected from polyethylene, polypropylene, acrylonitrile-butadiene-styrene (ABS), polylactic acid (PLA), polyglycolic acid (PGA), lactic acid-glycolic acid copolymer (PLGA), polybutyl acrylate (PBA), polybutylene terephthalate (PBT) and combinations thereof. The polymer can be water-based or solvent-based.

Combinations of more than one of the materials mentioned may also be used, provided they are compatible or adjusted for compatibility.

Polymers doped with metal oxide powders

According to certain embodiments, the metal oxide powder is incorporated into the polymer via masterbatch manufacturing.

As used herein, unless otherwise specified, the term "masterbatch" refers to a carrier polymer containing metal oxide particles formed into pellets or granules, where the polymer is compatible with the end-product material. The masterbatch can be added as a chemical additive to a polymer slurry containing the same or chemically compatible polymer prior to extrusion, molding, casting, or 3D printing. Alternatively, the masterbatch can comprise a composite resin containing the final dosage of polymer and metal oxide required to form a product from the polymer.

Metal oxide powders can be incorporated into polymers using a masterbatch system, such that the powder particles form part of the overall polymer product. However, currently known methods for preparing polymeric materials with antimicrobial properties are adapted to include 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 certain exemplary embodiments, the first and second metals are different. Thus, according to other 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 destructive to non-isotactic materials, such as most polymers, must be incorporated into a polymeric material, controlling the suspension and dispersion of the particles in the polymer slurry is complex. These slurries often produce uneven extruded or cast polymers. In masterbatch production, where it is often desirable to add a specific single compound to a polymer, dispersion and suspension of different metal oxide powders is not typically performed. Therefore, when reducing the present invention to practice, it is necessary to develop a method that allows for the incorporation of at least two metal oxide powders having substantially different specific gravities into polymer fibers. Furthermore, because the amount of any metal oxide powder that can be incorporated into a polymer is limited by the destructive effects of the metal oxides on cross-polymerization of non-isotactic polymers or by weakening of the carrier polymer, it is necessary to develop a method for accommodating large amounts of multiple metal oxides in these polymers. Therefore, the present invention provides a method for preparing a material having antimicrobial properties that provides control over the concentration and distribution of metal oxide particles in the polymer. The present invention also provides a material having antimicrobial properties that comprises a combination of at least two metal oxide powders, wherein the metal oxide powders are incorporated into the polymer fibers in an overall uniform manner. As used herein, the terms "generally uniform" or "homogeneous" are used interchangeably to mean that the volume percentage of metal oxide particles on the surface of the polymer or in the bulk thereof varies by less than 20%, preferably less than 10%.

According to certain embodiments, the materials of the present invention comprise at least two metal oxide powders having substantially different specific gravities. In another embodiment, "substantially different specific gravities" means that the specific gravities of the at least two metal oxide powders differ by more than about 5%. In another embodiment, the term refers to a difference of more than about 10%. In yet another embodiment, the term refers to a difference of more than about 15%.

In order to accommodate multiple metal oxide powders with different specific gravities in a single polymer slurry, it is necessary to compensate for the differences in the particle weights of the metal oxides. In order to do this, the bulk densities of the metal oxide powders should be equalized. When 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 certain embodiments, the material comprises at least two metal oxide powders that are processed to have substantially similar bulk densities. In certain embodiments, "substantially similar bulk density" means that the deviation of the bulk densities of the at least two metal oxide powders is less than about 20%. In another embodiment, the term means that the deviation is less than about 10%. In yet another embodiment, the term means that the deviation is less than about 5%.

For example, the specific gravity of copper oxide is 6.0 g/ml, while the specific gravity of tetrasilver tetroxide is 7.48 g/ml. Therefore, the bulk densities of the unprocessed copper oxide and tetrasilver tetroxide powders are significantly different. Without wishing to be bound by theory or mechanism of action, in order to be incorporated into the polymer in a substantially uniform manner, the powders must be processed to equalize their bulk densities. Equalizing the bulk densities of the metal oxide powders can be achieved by varying the particle size of the metal oxide powders. The particle size variation can be achieved by reducing or increasing the particle size of the powders. For example, the particle size of the powders can be reduced by grinding or increased by applying a coating. The extent to which the particle size of one metal oxide powder is increased or decreased compared to another metal oxide powder depends on the specific gravity and/or initial bulk density of the metal oxide powders.

According to certain embodiments, the metal oxide powder is processed by grinding. In other embodiments, the metal oxide powder is processed by milling. According to certain embodiments, the metal oxide powder is processed to have an average particle size that is inversely proportional to its specific gravity. According to another embodiment, the metal oxide powder is ground to have an average particle size that is inversely proportional to its specific gravity. According to other embodiments, the average particle size of the metal oxide powder is inversely proportional to its specific gravity.

According to other embodiments, the material comprises at least two metal oxide powders having substantially similar particle sizes. In another embodiment, "substantially similar particle sizes" means that the particle sizes of the at least two metal oxide powders vary by less than about 20%. In another embodiment, the term means that the variation is less than about 10%. In yet another embodiment, the term means that the variation is less than about 5%. In yet another embodiment, the term means that the variation is less than about 1%.

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

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

The metal oxide particle coating may comprise a polyester or polyolefin wax. Non-limiting examples of polyolefin waxes include polypropylene wax sold as Licowax PP 230 by Clariant, oxidized polyethylene wax sold as Licowax PED 521 by Clariant, oxidized polyethylene wax sold as Licowax PED 121 by Clariant, or ethylene homopolymer wax sold as BASF.

According to other embodiments, the coating material comprises a copolymer of polyethylene wax and maleic anhydride. According to other embodiments, the coating material further comprises an ionomer of a low molecular weight wax. According to other embodiments, the polyethylene wax has high wettability. In certain embodiments, the coating material comprises homopolymers, oxidized homopolymers, high density oxidized homopolymers and copolymers of polyethylene, polypropylene and ionomer waxes, micronized polyolefin waxes or mixtures thereof, and copolymers of ethylene-acrylic acid and ethylene-vinyl acetate.

A key prerequisite for the viability of such additive concentrates is the correct selection of the wax component. Although not inherently coloring, it influences the properties of the additive concentrate. For more detailed information, reference can be made, for example, to the product brochure "Luwaxe.RTM. - Anwendung in Pigmentkonzentraten" for polyethylene waxes from BASF AG.

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

According to other embodiments, the first metal and the second metal are the same. According to other embodiments, the at least two metal powders have substantially similar bulk densities.

Without wishing to be bound by theory or mechanism of action, in order to hinder the chemical interaction between the metal oxide powder and the carrier polymer or polymer fiber, the metal oxide should be pretreated with an encapsulating compound. The compound isolates the metal oxide so that they do not interact with the polymeric material and is configured to grind off the powder during product use. Therefore, according to certain embodiments, the material of the present invention comprises a metal oxide powder comprising particles encapsulated in an encapsulating compound. The encapsulating compound can be selected from silicates, acrylates, cellulose, protein-based compounds, peptide-based compounds, derivatives thereof, and combinations thereof. In certain embodiments, the encapsulating compound is selected from silicates, polymethyl methacrylate (PMMA), and combinations thereof.

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

Additionally or alternatively, the chemical interaction between the metal oxide powder and the carrier polymer or polymeric support can be hindered by adding a metal deactivator or chelator. As used herein, the terms "metal deactivator" and "chelator" are used interchangeably to refer to agents that generally comprise organic molecules containing heteroatoms or functional groups such as hydroxyl or carboxyl groups, which act by chelating metals to form inactive or stable complexes.

Thus, according to certain embodiments, the material of the present invention comprises a metal deactivator or chelating agent. In other embodiments, the material of the present invention comprises a metal deactivator or chelating agent associated with the metal oxide powder. Non-limiting examples of the metal deactivator and/or chelating agent include phenolic antioxidants, potassium iodide, potassium bromide, calcium stearate, zinc stearate, aluminum stearate, tertiary chain extenders, and combinations thereof. According to a specific embodiment, the metal deactivator is a phenolic antioxidant. The phenolic antioxidant may be selected from, but is not limited to, 2',3-bis[[3-[3,5-di-tert-butyl-4-hydroxyphenyl]propionyl]]propionohydrazide sold by CIBA under the name MD 1024, vitamin E (α-tocopherol) as a high molecular weight phenolic antioxidant sold by CIBA under the name E 201, B 1171 as a blend of hindered phenolic antioxidants and phosphates sold by CIBA, and combinations thereof. According to certain embodiments, the metal passivating agent abrades away the metal oxide particles after the material is hydrated.

According to certain embodiments, the weight of the metal deactivator applied to the powder is from about 0.2 wt.% to about 5 wt.% of the weight of the metal oxide powder. According to other embodiments, the weight of the metal deactivator is from about 0.5 wt.% to about 1 wt.% of the weight of the metal oxide powder. In one embodiment, the weight of the metal deactivator is about 1 wt.% of the weight of the metal oxide powder.

Another difficulty in adding almost any inorganic compound to a polymeric material is particle agglomeration. According to certain embodiments, the metal oxide particles of the present invention are treated with a surfactant to prevent metal oxide particle agglomeration. Therefore, according to certain embodiments, the material of the present invention comprises a surfactant. In other embodiments, the material comprises a surfactant associated with the metal oxide powder. Non-limiting examples of such surfactants include, but are not limited to, Sigma Aldrich, Dow Corning, and Triton-X-100.

According to certain embodiments, the surfactant accounts for about 0.05% to about 2% by weight of the metal oxide powder. In one embodiment, the surfactant accounts for about 0.5% by weight of the metal oxide powder.

According to certain embodiments, the metal oxide powder is present in the masterbatch in an amount of about 0.5% to about 95% by weight of the total weight of the masterbatch. According to other embodiments, the metal oxide powder is present in the masterbatch in an amount of about 5% to about 50%, preferably about 20% to about 40%. Each possibility represents a separate embodiment of the present invention. According to certain embodiments, the masterbatch is prepared for direct extrusion, molding, or casting without further mixing with other polymers. In certain such embodiments, the metal oxide powder is present in the masterbatch in an amount of about 0.5% to about 30% by weight of the total weight of the masterbatch, preferably about 0.5% to about 15% by weight of the total weight of the masterbatch. According to other embodiments, the metal oxide powder is present in the masterbatch in an amount configured to provide about 0.5 wt.% to about 30 wt.% of metal oxide particles in the material obtained by the masterbatch manufacturing process, preferably about 0.5% wt. to about 15 wt.% or about 1 wt.% to about 5 wt.% of metal oxide based on the total weight of the material. Each possibility represents a separate embodiment of the present invention.

The composition of the masterbatch comprising the synergistic combination of the polymer and the metal oxide can be formed into a semi-final or final product. The semi-final product can include, in particular, a fiber, a yarn, a textile, a fabric, a film or a foil, and the final product can include, in particular, a textile product or a non-woven polymer article. According to certain embodiments, the fiber is a synthetic or semi-synthetic polymer fiber. The fiber can be a staple fiber or a filament fiber. According to certain embodiments, the masterbatch composition is formed into a semi-final or final product by extrusion, molding, casting or 3D printing of the polymer comprising the synergistic combination. According to other embodiments, the material is selected from polymers that are extruded, molded, cast or 3D printed. Each possibility represents an independent embodiment of the present invention.

Thus, in certain embodiments, the metal oxide powder is present in the masterbatch in an amount configured to provide from about 0.5 wt.% to about 30 wt.% of the metal oxide particles in the extruded or molded polymer obtained by the masterbatch manufacturing process, preferably from about 0.5% wt. to about 15 wt.% or from about 1 wt.% to about 5 wt.% of the metal oxide based on the total weight of the extruded or molded polymer. Each possibility represents a separate embodiment of the present invention. In other embodiments, the metal oxide powder is present in the masterbatch in an amount configured to provide from about 0.5 wt.% to about 30 wt.% of the metal oxide particles in the polymer fiber obtained by the masterbatch manufacturing process, preferably from about 0.5% wt. to about 15 wt.% or from about 1 wt.% to about 5 wt.% of the metal oxide based on the total weight of the polymer fiber. Each possibility represents a separate embodiment of the present invention.

In certain embodiments, the combined weight of the at least two metal oxides comprises from about 0.25% to about 50 wt.% of the total weight of the material.

In certain embodiments, the material is in the form of a semi-final product selected from a fiber, a yarn, a textile, a fabric, a film, or a foil. In certain such embodiments, the combined weight of the at least two metal oxides accounts for about 0.5 wt.% to about 30 wt.% of the total weight of the semi-final product.

According to other embodiments, the combined weight of the at least two metal oxides is from about 1 wt.% to about 15 wt.% of the total weight of the semi-final product. In certain such embodiments, the polymer is selected from polyester or polyamide. In other embodiments, the semi-final product is a fiber, preferably comprising staple fibers. According to certain embodiments, the combined weight of the at least two metal oxides is from about 1 wt.% to about 5 wt.% of the total weight of the semi-final product. According to other embodiments, the combined weight of the at least two metal oxides is from about 3 wt.% to about 8 wt.% of the total weight of the semi-final product.

According to other embodiments, the combined weight of the at least two metal oxides accounts for about 0.5 wt.% to about 8 wt.% of the total weight of the semi-final product. In some such embodiments, the polymer is selected from polyester or polyamide. In other embodiments, the semi-final product is a fiber, preferably comprising a filament fiber. According to certain embodiments, the combined weight of the at least two metal oxides accounts for about 1 wt.% to about 4 wt.% of the total weight of the semi-final product. According to other embodiments, the combined weight of the at least two metal oxides accounts for about 0.5 wt.% to about 2 wt.% of the total weight of the semi-final product.

According to other embodiments, the combined weight of the at least two metal oxides is from about 10 wt.% to about 30 wt.% of the total weight of the semi-final product. In certain such embodiments, the polymer is a polyolefin. In other embodiments, the semi-final product is a fiber.

In certain embodiments, the combined weight of the at least two metal oxide powders comprises from about 3 wt.% to about 8 wt.% of the total weight of the material, and the metal oxide particles have a particle size of from about 0.5 to about 1 micron. In a specific embodiment, the combined weight of the at least two metal oxide powders comprises from about 3 wt.% to about 8 wt.% of the total weight of the material, and the metal oxide particles have a particle size of about 1 micron. In other embodiments, the combined weight of the metal oxide powders comprises from about 8 wt.% to about 0.5 micron.

In certain embodiments, the polymer fiber is blended with a natural fiber. The natural fiber can be selected from cotton, silk, wool, flax, and combinations thereof. In other embodiments, the material further comprises a modified cellulose fiber. Non-limiting examples of modified cellulose fibers include viscose and rayon.

According to certain embodiments, the natural fibers may be present in the material in an amount of up to about 95% by weight of the total weight of the material. In other embodiments, the material of the present invention comprises from about 50% to about 85% by weight of natural fibers. According to certain exemplary embodiments, the natural fibers may be present in the material in an amount of about 70% by weight of the total weight of the material. According to other embodiments, the weight ratio between the polymer fibers into which at least two metal powders are incorporated and the natural fibers is from about 1:1 to about 1:6. Thus, the blended material may comprise from about 50% by weight natural fibers/50% by weight polymer fibers to about 85% by weight natural fibers/15% by weight polymer fibers. In certain embodiments, the material comprises from about 50% by weight cotton/50% by weight polymer fibers to about 85% by weight cotton/15% by weight polymer fibers.

According to certain embodiments, the material comprises a semi-final product comprising a blend of polymer fibers and natural fibers. In certain such embodiments, the combined weight of the at least two metal oxides comprises from about 0.25 wt.% to about 5 wt.% of the total weight of the semi-final product.

In certain embodiments, the material comprises 100 wt.% of polymer fibers having at least two metal powders incorporated therein. Thus, the material of the present invention may be free of natural fibers.

According to certain embodiments, the weight of the mixed oxidation state oxide accounts for about 0.001 wt.% to about 30 wt.% of the total weight of the material. In certain embodiments, the mixed oxidation state metal oxide accounts for about 0.05 wt.% to about 2.5 wt.% of the total weight of the material, preferably about 0.1 wt.% to about 1 wt.% of the total weight of the material. Each possibility represents a separate embodiment of the present invention. The material can be selected from intermediate, semi-final, and final materials.

According to certain embodiments, the material having antimicrobial properties comprises a polymer and a synergistic combination of at least two metal oxide powders, wherein the powders are incorporated into the polymer. According to certain embodiments, the metal oxide powders are attached to the polymer. According to other embodiments, the powders are attached to the surface of the polymer. According to other embodiments, the powders are embedded in the polymer. According to other embodiments, the powders are embedded in the surface of the polymer. According to other embodiments, the powders are deposited on the surface of the polymer. According to other embodiments, the powders are inserted into the polymer. According to other embodiments, the powders are inserted into the surface of the polymer. According to other embodiments, the metal oxide powder particles protrude from the surface of the polymer. According to other embodiments, at least a portion of the metal oxide powder particles protrude from the surface of the polymer. According to certain embodiments, at least 10% of the synergistic combination of metal oxides is present on the surface of the polymer. According to other embodiments, at least 5% of the synergistic combination of metal oxides is present on the surface of the polymer. It has been found that as little as 1% of the presence of particles protruding from the polymer surface on the surface of polymer fibers is sufficient to ensure a biocidal effect. Therefore, according to certain embodiments, at least 1% of the synergistic combination of metal oxides is present on the surface of the polymer. According to other embodiments, the powder is not exposed on the surface of the polymer. According to certain embodiments, the polymer is an extruded, cast or molded polymer, or is in the form of a polymer fiber, a textile product or a non-woven polymer article. Each possibility represents a separate embodiment of the present invention.

End products

The material of the present invention comprises a polymer and at least two metal powders incorporated therein, wherein the polymer can be extruded, molded, cast, or 3D printed. According to certain embodiments, the polymer is a molded polymer. In other embodiments, the polymer is an extruded polymer. In certain embodiments, the polymer is in the form of a fiber. According to certain embodiments, the fiber can be formed into a yarn, a textile, or a fabric. According to certain embodiments, the textile is selected from a woven fabric, a knitted fabric, a non-woven fabric, a needle-punched fabric, or a felt.

According to certain embodiments, the final product comprises a monolithic layer obtained by stacking nanodenier fibers, such as those produced using an electronic spinning process, the fibers comprising a synergistic combination of the metal oxide powders. In certain embodiments, the metal oxide particles are disposed between the nanofibers in the sheath.

Also provided according to certain embodiments of the present invention are extruded polymers in the form of staple or filament fibers comprising the metal oxide particles incorporated into polymer fibers and formed into non-extruded nonwoven materials or fillers.

According to other embodiments, the semi-final product can be formed into a final product. According to certain embodiments, the final product of the present invention has a soft surface. When used in this article, the term "soft surface" refers to all surfaces that are solid but not hard surfaces, and most generally refers to products made from knitted, woven or non-woven textiles. The final product of the present invention includes but is not limited to textile products and non-woven polymer products.

The textile products may be selected from, but are not limited to, articles of clothing, bedding textiles, laboratory or hospital textiles including bandages or sutures and textiles for internal use, and personal hygiene products. Non-limiting examples of the textile products include pillowcases, eye masks, gloves, socks, stockings, sleeves, shoe covers, slippers, underwear, industrial uniforms, sportswear, towels, kitchen cloths, lab coats, floor cloths, bed sheets, bedding, curtains, textile covers, hard surface covers, diapers, incontinence pads, feminine hygiene products, gauze pads, monolithic extruded films, bodysuits, transdermal patches, bandages, adhesive bandages, sutures, sheaths and textiles for internal use, compression garments of all sizes for different parts of the body, and absorbent pads.

The nonwoven polymeric article may be selected from, but is not limited to, packaging and wrapping materials, laboratory equipment, hospital equipment, preferably disposable hospital equipment, closures for consumer products, food equipment, agricultural products, sanitary products, or contraceptive devices. Non-limiting examples of the nonwoven polymeric article include food packaging, gloves, blood bags, catheters, ventilation tubes, feeding tubes, delivery tubes, mobile phone housings, pipes, toilet seats or toilet seat covers, kitchen sponges, work surface covers, and condoms.

Products formed from the materials of the present invention possess effective antimicrobial properties, including but not limited to antimicrobial, antibacterial, antiviral, antifungal, and antimite properties.

Thus, according to certain embodiments, the present invention provides materials for combating or inhibiting the activity of a microorganism or microorganism selected from Gram-positive bacteria, Gram-negative bacteria, fungi, parasites, molds, spores, yeasts, protozoa, algae, mites, and viruses. Each possibility represents a separate embodiment of the present invention. According to certain embodiments, the present invention provides methods for combating or inhibiting the activity of a microorganism or microorganism, comprising providing a material according to the principles of the present invention to a healthcare facility.

According to certain embodiments, the material is used to combat healthcare associated infection, nosocomial infection, or a combination thereof. According to certain embodiments, the present invention provides a method of combating healthcare associated infection, nosocomial infection, or a combination thereof, comprising providing a material according to the principles of the present invention to a healthcare facility.

The materials of the present invention may be particularly useful for controlling hospital-acquired infections, reducing odors in clothing, socks, stockings, and underwear, and in wound healing products such as gauze, wound covers, disposable sanitary products, disposable diapers and sutures, single-use clothing, diapers, and articles of clothing that may come into contact with wounds.

Alternatively or in addition, the materials of the present invention can be used to treat or prevent atopic fungal, bacterial, and viral infections. The infection can be selected from athlete's foot, yeast infection, and staphylococcal infection. In other embodiments, the materials are used to treat or prevent surface viral infections. The infection can be selected from warts and herpes B. According to certain embodiments, the present invention provides a method for treating or preventing atopic fungal, bacterial, and viral infections, comprising applying a material according to the principles of the present invention to a body surface of a subject in need of such treatment.

Thus, according to the principles of the present invention, products, preferably textile products, for controlling fungal infections, yeast infections, and/or viral infections on surfaces are also provided. In certain embodiments, the metal oxide powder incorporated into the polymer can be further incorporated into a film, fiber, textile patch, or a form selected from socks, shorts, underwear, sleeves, and patches that can be placed on an infected area. According to certain embodiments, the metal oxide particles are incorporated into fibers incorporated into a substrate made of a film or a textile, nonwoven material, or textile substrate for use against dust mites.

Preparation method

In another aspect, the present invention provides a method for preparing a material consistent with the principles of the present invention, the method comprising the steps of:

a. processing the at least two metal oxide powders to obtain substantially similar bulk density; and

b. Mixing the powder with at least one polymer.

According to certain embodiments, step a. comprises processing the metal oxide powder to obtain particles having a particle size that is inversely proportional to its specific gravity. According to certain embodiments, step a. comprises reducing the particle size of the metal oxide powder to obtain particles having a particle size that is inversely proportional to its specific gravity. According to other embodiments, step a. comprises processing the metal oxide powder to obtain particles having a substantially similar particle size. According to other embodiments, step a. comprises reducing the particle size of the metal oxide powder to obtain particles having a substantially similar particle size. In certain embodiments, the processing comprises grinding.

In other embodiments, step a. further comprises applying a coating to the metal oxide powder particles. According to certain embodiments, the thickness of the coating is proportional to the specific gravity of the metal oxide particles. According to other embodiments, the weight of the coating is proportional to the specific gravity of the metal oxide particles. According to certain embodiments, the coating is applied to metal oxide powders having substantially similar particle sizes. According to other 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 other embodiments, the coating comprises a polyester or polyolefin wax. The polyester or polyolefin wax can be selected from 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 certain embodiments, the method further comprises the step of encapsulating the metal oxide powder particles within an encapsulating compound. In other embodiments, the method further comprises the step of mixing the metal oxide powder with a metal passivator or chelating agent. In other embodiments, the method further comprises the step of mixing the metal oxide powder with a surfactant. In certain embodiments, the other steps are performed prior to mixing the metal oxide powder with the polymer.

The encapsulating compound may be selected from silicates, acrylates, cellulose, derivatives thereof, and combinations thereof. The metal deactivator may be selected from phenolic antioxidants, potassium iodide, potassium bromide, calcium stearate, zinc stearate, aluminum stearate, tertiary chain extenders, and combinations thereof.

In other embodiments, the method includes preparing the mixed oxidation state oxide. The mixed oxidation state oxide can be prepared by standard procedures, such as those described by Hammer and Kleinberg in Inorganic Synthesis (IV, 12) or in U.S. Patent No. 5,336,416, which are incorporated herein by reference in their entirety. The method may also include the step of grinding the obtained mixed oxidation state oxide powder.

According to certain embodiments, the mixing of the metal oxide powder and the at least one polymer is facilitated by sonication. According to other embodiments, the metal oxide powder is mixed with polymer fibers. According to other embodiments, the metal oxide powder is embedded in the polymer fibers by sonication.

According to other embodiments, step b. comprises producing a masterbatch comprising the metal oxide powder and a carrier polymer. According to certain embodiments, the at least one polymer comprises the carrier polymer. According to preferred embodiments, the masterbatch is homogeneous. According to other embodiments, the metal oxide powder is distributed throughout the masterbatch in a generally uniform manner. The masterbatch can be formed into pellets. Alternatively, the masterbatch can be formed into granules. The carrier polymer can be selected from the group consisting of polyamides, polyolefins, polyurethanes, polyesters, and combinations thereof.

In certain embodiments, step b. further comprises adding the masterbatch to the polymer slurry. In other embodiments, the polymer slurry comprises the same polymer as the carrier polymer. In other embodiments, the polymer slurry comprises a polymer that is chemically compatible with the carrier polymer. In certain embodiments, the polymer is selected from polyamides, polyolefins, polyurethanes, and polyesters. Combinations of more than one of the materials may also be used, as long as they are compatible or adjusted to be compatible. The polymer raw material is typically in the form of beads and can be monocomponent, bicomponent, or multicomponent in nature. The beads are heated to melt, preferably at a temperature in the range of about 120°C to 180°C for isotactic polymers and up to 270°C for polyesters. The masterbatch is then added to the polymer slurry and allowed to spread through the heated slurry. In these embodiments, the particle size of the metal oxide powder is preferably between 1 and 5 microns. However, the particle size may be larger when the thickness of the film or fiber can accommodate larger particles.

According to certain embodiments, the metal oxide is directly incorporated into the polymer fibers. According to other embodiments, the metal oxide powder has a particle size between 0.1 and 0.5 microns. According to other embodiments, the incorporation of the metal oxide powder into the polymer fibers is aided by sonication.

According to certain embodiments, the method further comprises step c., which comprises forming a semi-final or final product from the obtained mixture. Thus, in certain embodiments, the method further comprises step c., which comprises forming a film, foil, fiber, yarn, fiber or textile comprising the powder from the obtained mixture. Each possibility represents an independent embodiment of the present invention. According to other embodiments, the method comprises the step of forming the film, foil, fiber, yarn, fiber or textile into a textile product or a non-woven polymer article.

In certain embodiments, step c. comprises extrusion, molding, casting or 3D printing of the mixture obtained in step b. In certain exemplary embodiments, step c. comprises extrusion. In certain such embodiments, the polymer slurry is transferred to an extrusion tank. In other embodiments, the liquid polymer slurry is pushed out through a series of holes in a circular metal plate called a spinneret. The polymer slurry is pushed out through the spinneret by applying pressure on the slurry. When the slurry is pushed out through the tiny holes next to each other, they form single fibers, or if allowed to contact each other, they form a film or sheath. The hot liquid fiber or film is pushed upward and cooled with cold air to form a series of continuous fibers or discs. The thickness of the fiber or disc is controlled by the size of the hole and the speed at which the slurry is pushed out through the hole and pushed upward by the cooling air flow. In a preferred embodiment, the fibers are extruded uniformly.

In certain embodiments, step c. includes forming a polymer fiber from the mixture obtained in step b. The fiber can be formed in the form of a filament (continuous) or a staple fiber (chopped). In both cases, a certain amount of masterbatch is added to the hot polymer slurry to obtain the final amount of the combination of the at least two metal oxide powders required for the end product. For example, if a final loading of 1% is required in the filament fiber, 50 kilograms of a 20wt.% concentrated masterbatch will be added to complete 1 ton of total slurry. For example, if a final loading of 3% is required in the staple fiber, 150 kilograms of a 20wt.% concentrated masterbatch will be added to complete 1 ton of total slurry. In both cases, after the concentrated masterbatch is fully mixed in the slurry barrel to obtain a good masterbatch dispersion, the extruded fiber will contain the desired amount of the metal oxide combination.

In the usual process known to those skilled in the art, the active ingredient will be evenly dispersed and retained in a suspension of the polymer slurry. If the masterbatch is not correctly prepared, the metal oxide will interact with the target polymer and destroy the coupling process, thereby inhibiting the formation of solid fibers. In addition, if the wax is not correctly applied, the metal oxide will sink to the bottom of the mixing barrel and block the holes of the spinneret, or will remain floating on the top of the slurry and not be mixed into the fiber. Typically, extrusion is carried out using gravity so that the weight of the slurry in the barrel pushes the polymer through the holes of the spinneret. The polymer is designed to solidify as it is exposed to air. Once the fibers are exposed to air, they are wound on a spool for further processing.

According to certain embodiments, the fiber is selected from staple fibers, filament fibers, and combinations thereof. According to certain embodiments, the polymer fiber is a synthetic or semi-synthetic fiber. According to other embodiments, the synthetic or semi-synthetic fiber is selected from polyolefin fibers, polyurethane fibers, vinyl fibers, nylon fibers, polyester fibers, acrylic fibers, cellulose fibers, regenerated protein fibers, blends thereof, and combinations thereof. In certain embodiments, the method further comprises blending the polymer fiber with a natural fiber. According to other embodiments, the natural fiber is selected from cotton, silk, wool, flax, and combinations thereof.

According to other embodiments, the method includes forming the polymer fiber into a yarn. According to certain embodiments, the yarn is a synthetic yarn or a combination of synthetic and natural yarns. In certain embodiments, the synthetic yarn is spun from the synthetic fiber. According to other embodiments, the yarn is formed into a fabric. According to other embodiments, the fabric is a woven, braided, or non-woven fabric.

In other embodiments, the method further comprises forming the material into a textile product or a non-woven polymer article. According to other embodiments, step c. comprises directly forming a textile product or a non-woven polymer article from the mixture obtained in step b. Each possibility represents a separate embodiment of the present invention. In certain such embodiments, step c. comprises molding, casting, or extruding the mixture obtained in step b. into a desired shape or form. In certain embodiments, step c. comprises applying the mixture of the metal oxide powder obtained in step b. and at least one polymer to a prefabricated polymer article as a second layer. In certain embodiments, the polymer is latex, nitrile, or synthetic rubber.

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

Example

Example 1: Preparation of mixed oxidation state oxide powder

Tetrasilver tetroxide powder is prepared from silver nitrate by a reduction method using standard procedures known to those skilled in the art and as described by Hammer and Kleinberg in Inorganic Synthesis (Vol. IV, p. 12). It should also be noted that the powder obtained by the method described should be very soft and can be converted into nanopowders relatively easily.

The basic tetrasilver tetroxide (Ag ₄ O ₄ ) synthesis referred to above was prepared by adding NaOH to distilled water, followed by potassium persulfate, and then silver nitrate.

Tetracopper tetroxide powder can be prepared using copper sulfate and potassium persulfate as oxidants as described in Antelman, US Patent 5,336,416. However, for commercial viability reasons, cuprous oxide was purchased and used as the starting material _{to obtain Cu4O4 following} the described procedure.

The particle sizes of both powders as received varied from nanoparticles to agglomerated particles as large as 20 microns.

These powders can be ground to the desired particle size and mixed together or with copper oxide or zinc oxide. The copper oxide used in the development was cuprous oxide (brown/red) with a purity level of at least 97% and a particle size of 10-20 μm. In this case, the powder was purchased from SCM Inc. of North Carolina, USA, but it could be purchased from any supplier that could provide this purity level. The powder was then ground to 1 to 5 μm. Since suppliers of such powders are very common, it is not economically viable to manufacture the powders. However, due to the difficulty in obtaining tetrasilver tetroxide and/or tetracopper tetroxide, it is necessary to synthesize the specific substances as described above.

Example 2: Masterbatch preparation

The metal oxide is incorporated into the polymer using a masterbatch system so that the powder is embedded on the outside of the polymer and forms part of the overall polymeric product.

In order to accommodate more than one metal oxide of different specific gravities in the same masterbatch, it is necessary to compensate for the difference between the two different metals, if there is a difference in their weight. This is done using the two systems described:

In the first system, the particle size of each metal oxide is equalized by proportional particle 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. The tetrasilver tetroxide particles are ground to be approximately 10% to 15% smaller than the copper oxide particles.

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

The wax is applied to a high shear mixer at a weight/weight ratio of about 10 grams of wax to 1000 grams of metal oxide. It has been found that a larger amount of polyester wax on the heavier metal oxide helps to maintain the suspension of the metal oxide in the polymer slurry. The wetting ability of the wax should also be good. In order to isolate the chemical interaction of the metal oxide and the carrier polymer, the metal oxide powder is pretreated with an encapsulating compound. The inert encapsulating compound used is a silicate and polymethyl methacrylate (PMMA). The encapsulation is carried out in a high shear mixer at a weight/weight ratio of about 4 grams of encapsulating agent to 1000 grams of metal oxide powder.

Example 3: Polymer and Blended Polymer Fiber and Yarn Preparation

The production of polymer yarns with antimicrobial properties featuring metal oxide particles protruding from the polymer surface in filament and staple fiber products is described.

It should be noted that for the purposes of this embodiment, tetrasilver tetroxide and/or tetracopper tetroxide and/or copper oxide were used, but other metal oxide compounds may be used in the same approximate proportions.

The general production method of fibers is described below:

1. Prepare a slurry from any polymer, preferably the primary raw material selected from polyamides, polyolefins, polyurethanes, and polyesters. Combinations of more than one of these materials may also be used, provided they are compatible or adjusted for compatibility. The polymer raw material is typically in the form of beads and may be monocomponent, bicomponent, or multicomponent in nature. The beads are heated to a melt, preferably at a temperature in the range of about 120 to 180°C for isotactic polymers and up to 270°C for polyesters.

2. During the hot mix stage, prior to extrusion, a water-insoluble powder of the selected metal oxide compound in masterbatch form is added to the slurry and allowed to spread through the heated slurry. Particle size is preferably between 1 and 5 microns, however, larger particle sizes can be used when the thickness of the film or fiber can accommodate larger particles.

3. Pressure is then used to push the liquid slurry through a series of holes in a circular metal plate called a spinneret. As the slurry is pushed through the closely spaced holes, it forms a single fiber, or if allowed to contact one another, a film or sheath. The hot liquid fiber or film is pushed upward and cooled by cold air, forming a series of continuous fibers or discs. The thickness of the fibers or discs is controlled by the size of the holes and the speed at which the slurry is pushed through the holes and pushed upward by the cooling air flow.

filament fiber

It should be noted that the specific gravity of each metal oxide is different and therefore requires treatment with different coating compounds or application of different amounts of the same coating compound so that the two metal oxide powders are uniformly dispersed in the liquid polyester slurry. The metal oxide particles are mixed with the support and formed into pellets. When it comes to filament fibers, this produces a total of 50 kg of masterbatch, which is entirely copper oxide, and/or tetrasilver tetroxide and/or tetracopper tetroxide together. The ratio of the support to the active material is 5:1, resulting in a 20 wt.% concentration of the metal oxide in the masterbatch. The 50 kg of the masterbatch are mixed in an extrusion tank for spinning through a spinneret and are sufficient to produce 1 ton of filament polymer yarn, obtaining a final concentration of 1% of the two metal oxides (active materials) together in the polymer yarn. It should be noted that if the particle size of the particles is below 0.5 microns, it has been found that the loading of the metal oxide in the filament fibers can be increased to as much as 4 wt.%.

short fibers

To produce staple fibers, 28.5 kg of copper oxide ground to a particle size of 1 to 5 microns and 1.5 kg of tetrasilver tetroxide ground to a particle size of 1 to 5 microns are mixed with 120 kg of the selected carrier polyester polymer to create a masterbatch. Each compound has a different specific gravity, necessitating coating with different coating compounds, such as Clariant Licowax PP230 and BASF, or with varying amounts of the compounds, to achieve a uniform dispersion of the metal oxide particles in the suspension. The compounds are mixed with the carrier and formed into pellets. This yields a total of 150 kg of masterbatch. This 150 kg masterbatch is mixed in an extrusion tank for spinning through a spinneret and is sufficient to produce 1 ton of polymer staple yarn, resulting in a final concentration of 3 wt.% of both compounds in the polymer fibers.

Figures 1A-1C present scanning electron microscope (SEM) micrographs of polyester staple fibers doped with a combination of copper oxide and tetrasilver tetroxide powder. The polymer fibers were prepared using the masterbatch method as described above. It can be seen that the metal oxide particles are uniformly distributed on the surface of the polymer fibers. It can also be seen that the synergistic combination of metal oxide particles protrudes from the surface of the polymer fibers.

As a comparative study, Figures 2A and 2B represent cotton fibers containing sonochemically deposited copper oxide and further impregnated with tetrasilver tetroxide. The larger particles are tetrasilver tetroxide particles and the smaller particles are copper oxide particles.

Furthermore, it has been found that due to the isotactic nature of olefins, loading levels in polyolefin fibers can be much higher than in polyester or nylon fibers. While the loading levels discussed above are limited to 1 wt.% in filament fibers and 3 wt.% in staple fibers, it has been found that up to 20 wt.% can be added to polypropylene fibers.

Staple and filament fibers combined with cotton

The masterbatch was produced as described above using a polyester resin to which was added 20 wt.% of a mixture comprising copper oxide and TST. Both the copper oxide and TST were approximately 98% pure. The metal oxide composition comprised 99.5% copper oxide and 0.5 wt.% TST. The masterbatch was then added to a polyester slurry in liquid form in a proportion to produce a final copper oxide loading of approximately 3 wt.% in the final fiber. The copper oxide in the sample was 97.7% pure, with 2.3% being impurities. The fiber was extruded in the same manner as normal chopped polyester fiber and then blended with cotton so that the final loading of the treated fiber was a total of 30 wt.% copper oxide and TST impregnated fiber/70% cotton, formed into a 24/1s twisted ring-spun combed cotton yarn for weaving. The yarn was then knitted into a fabric weighing 150 grams per square meter.

It should be noted that no degradation of physical properties was observed in mixtures containing up to 10 wt. % of the metal compounds. As described below, materials with as little as 0.5 wt. % of the metal oxide combination exhibited limited efficacy in antimicrobial properties and surprising inhibition of HIV-1 activity.

Example 4: Preparation of short fibers with encapsulated metal oxide powder

Polyester staple fibers were prepared by combining 2.85 wt.% copper oxide powder with 0.015 wt.% tetrasilver tetroxide powder, based on the total fiber weight. The metal oxide particles were reduced to a size between 0.25 and 0.35 microns and incorporated directly into the polymer fibers. The process involved milling the powder to the desired size, depositing the powder onto the fibers, and passing the powdered fibers through a water bath through which ultrasound was passed.

Figure 3 shows an SEM micrograph of the fiber obtained by the process, in which copper oxide and TST particles are below the surface, which appear as unclear white spots in the SEM micrograph. The particles on the fiber surface in the photo were evaluated by spectroscopic readings and were found not to be copper oxide or TST, but rather a complex combination of organic groups in the polymer itself.

Example 5: Preparation of polymer yarn by standard extrusion method

The masterbatch was prepared following the same procedure as in Example 3, but the yarn was obtained by a procedure involving standard film extrusion equipment. The viscosity of the slurry was controlled by the masterbatch flow rate by a procedure known to those skilled in the art.

Example 6: Preparation of molded polymer

Powders and masterbatches comprising the combined powders containing copper oxide and TST, as well as polypropylene, are prepared as described above. The masterbatch must be adapted to the carrier polymer slurry to which it will be added. In molded and/or cast products, the masterbatch concentration can be any amount up to and including 40% active ingredient, however, to avoid possible problems with chemical dispersion in the slurry, amounts of 20% to 25% would be preferred. The masterbatch is allowed to melt in the polymer slurry until the slurry is uniform. No temperature changes are made. The polymer slurry is then cast into the desired form or extruded to produce a product of a specific shape. The polypropylene slurry is extruded into a polypropylene film having copper oxide and TST incorporated therein.

Example 7: Preparation of cellulose-based polymer yarn

Rayon pulp, or any cellulose pulp (cotton and corn waste are very common cellulose sources), is mixed with plasticizers known in the industry for producing these types of fibers. Typically, the process involves a number of chemical steps that include breaking down the cellulose into a very fine covering of individual cells, adding the plasticizer, and then exposing the pulp to a curing process.

A powder consisting of a combination of two metal oxides including copper oxide and tetrasilver tetroxide is prepared. The metal powders are thoroughly mixed together and ground to a particle size preferably less than 5 μm.

The powder is then added to the cellulose-based slurry at a rate of up to 3 wt.% of powder relative to the total weight of the slurry. The powder is added precisely while the slurry passes 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 manufacture of these fibers.

The resulting slurry is solidified so that the metal oxide particles uniformly penetrate the entire fiber.

Example 8: Preparation of latex gloves

A natural latex slurry is prepared using the desired amount of latex solids with water and other compounds. In the case of gloves, there is typically between 20% and 35% latex solids. The slurry is heated and a glove mold is dipped into the liquid and removed. Excess latex is allowed to drip from the glove, still on the mold, thereby creating a thin layer of latex on the mold. The latex and mold are then placed in an oven, which cures the latex at a temperature required to cause the material to crosslink. This first cure of the latex converts the liquid latex into latex solids. The latex layer is allowed to cool, but remains adhered, until it is dried by a second exposure to dry heat. After the first cure, the latex crosslinks and now takes the form of a flexible film within the mold, but still in an adhered state.

While the latex on the mold is still adhered but solid, and before the second exposure to heat, a second bath is prepared. The mold and adhered latex are immersed in a latex slurry a second time. This second bath is also a latex slurry, but contains up to, but not limited to, 5 wt.% latex solids and 0.25 wt.% of a mixture of copper oxide and TST. This amount of copper oxide and TST has been found to be sufficient for antimicrobial and antiviral effects. When the adhered molded glove is immersed in the dilute latex copper oxide and TST bath, a very thin colored coating is produced that is visible on the glove. At this stage, it has also been found that pigment can be added to the slurry to change the color of the glove, if desired.

The particle size of the copper oxide and TST in the system was measured to be approximately 5 μm, but this procedure can be performed using both smaller and larger particles.Preferably, the copper oxide particles protrude from the surface of the latex.

It should be noted that the second latex soak merely acts as a binder for the copper oxide and adheres excellently to the latex underneath, allowing the exposed copper oxide and TST mixture to adhere to the latex without any negative weakening of the latex glove. The mold with the two layers of latex is cured a second time and passed through a drying process. Due to its low thickness, the outer layer does not require another cure.

Example 9: Antimicrobial Properties of Metal Oxides

This example contains several experiments that were conducted to test the antimicrobial properties of combinations of single and mixed oxidation state oxides.

Test 1: Antiviral performance

100 μl aliquots of freshly prepared HIV-1 were incubated on top of fibers produced according to the procedure described in Example 3 and having various amounts and ratios of copper oxide and tetrasilver tetroxide as presented in Table 1. The incubation was carried out at 37°C for 30 minutes. 10 μl of each incubated viral solution was then added to MT-2 cells (human lymphocyte cell line) cultured in 1 ml of neutral medium. The cells were then incubated at 37°C in a humidified incubator for 5 days, and viral proliferation was determined by measuring the amount of p24 (HIV-1 capsid protein) in the supernatant using a commercial ELISA (enzyme-linked immunosorbent assay) kit. The results show the average of two parallel experiments. As a control for the possible cytotoxicity of the combination of Ag ₄ O ₄ and copper oxide to the cells, a similar experiment was performed as described above. The fibers were incubated with 100 μl of standard/control medium that did not contain HIV-1. No cytotoxicity was observed.

Table 1 summarizes the evaluation of the ability of fibers containing a combination of Ag ₄ O ₄ and copper oxide to inhibit HIV-1 proliferation in tissue culture compared to fibers containing copper oxide or tetrasilver tetroxide alone and fibers without metal oxides.

Table 1: Antiviral efficacy test results

Test No. Polymer fiber active materials inhibition(%) 1 Control – no antiviral agent 0 2 70 3 Contains 1wt.% TST 76 4 96

Test 2: Antibacterial, antifungal and anti-mite properties

Extruded polypropylene films containing a combination of copper oxide and TST were used to test the antibacterial properties of extruded polymers containing a synergistic combination of metal oxides. The films were prepared as described in Example 5. In all cases, the mixed oxidation state oxide, tetrasilver tetroxide, and the single oxidation state oxide, copper oxide, together accounted for 3 wt.% of the total weight of the extruded film. The metal oxide mixture comprised 3 wt.% TST and 97 wt.% copper oxide. As a control, a polypropylene film containing a single oxidation state oxide as the sole active ingredient was tested to observe the level of microbial inhibition. As a control for the combined metal oxide activity, a polypropylene film was extruded with copper oxide and an elemental silver ceramic compound, commonly used as a silver-based antimicrobial material, thereby providing a polymer with a combination of two single oxidation state oxides. The combined weight of the copper oxide and silver ceramic compound powders accounted for 3 wt.% of the total weight of the extruded film. The combined powders comprised 3 wt.% silver (a silver-based antimicrobial additive from Milliken, Inc., USA) and 97% copper oxide.

Polymer fibers combined with cotton containing a combination of copper oxide and TST were used to test the dust mite biocidal properties of fibers containing a synergistic combination of metal oxides. The polymer/cotton blend fibers were prepared as described in Example 3. The metal oxide composition contained 99.5 wt.% copper oxide and 0.5 wt.% TST. The blended fibers contained 30 wt.% copper oxide and TST impregnated fibers and 70% cotton. As a control, a 70% polymer/30% cotton blend fiber containing a single oxidation state oxide as the sole active ingredient was used. The positive control was made exactly as described for the copper oxide and TST combination, but without the TST, such that the active ingredient was 100% copper oxide. A negative control was also made identically to the two other fibers, but without the active ingredient.

The biocidal properties of the films against the bacteria and fungi tested were determined using the American Association of Textile Chemists and Colorists (AATCC) Test Method 100. The initial bacterial or fungal inoculum used varied between 1 x 10 ⁵ and 4 x 10 ⁶ colony forming units (CFU) per ml. However, in an attempt to observe the pure effect of the metal oxide, the bacteria-containing sample films used in these tests were diluted with saline solution to highly dilute and remove the growth medium from the films, and when incubated at 25° C. and 70% relative humidity, bacterial proliferation was significantly reduced.

For each membrane biocidal activity evaluation against each microorganism, microorganism levels were measured at 5 minute intervals. The times reported below relate to the time required to achieve a kill rate that provided a 99% reduction (2 log reduction) in microorganism levels.

The tested antibacterial properties of materials comprising a combination of two single oxidation state oxides instead of a combination of a mixed oxidation state oxide and a single oxidation state oxide, compared to those of the single oxidation state oxides alone, are presented in Table 2. The tested antibacterial, antiviral, and antimite properties of materials comprising a combination of a mixed oxidation state oxide and a single oxidation state oxide, compared to those of the single oxidation state oxides alone, are presented in Table 3. The tested antibacterial properties of polypropylene extruded films comprising a combination of copper oxide and TST, compared to a control of the same fiber without any active ingredient, are presented in Figure 4.

Except for the last test in Table 3 (dust mite), time was measured at 5 minute intervals until a 99% reduction in microbial levels was achieved. All tests were performed in triplicate, and the results in the table represent the average. In the last test (dust mite, on 70% cotton, 30% polyester), time was measured at 24 hour intervals until a 99% reduction in microbial levels was achieved.

As can be seen from Table 2, the addition of copper oxide did not reduce the time required for a 2 log reduction found with polypropylene films containing and copper oxide. In contrast, Table 3 shows that polymeric films and fibers comprising tetrasilver tetroxide (silver in mixed oxidation state form) in combination with copper oxide had higher biocidal activity than films and fibers containing copper oxide alone, as indicated by the shorter time required to achieve a 2 log reduction.

Table 2: Antibacterial properties of polymeric materials comprising a combination of two single oxidation state oxides

Table 3: Antibacterial, antiviral and antimite properties of materials comprising a combination of mixed oxidation state oxides and single oxidation state oxides

* 100 dust mites were placed on a film with food in an incubator at 37°C and 70% relative humidity. Mortality was counted daily.

Example 10: Proliferation Inhibition Testing of Polymer Fabrics Using AATCC Test Method 100-2004

A previous set of experiments (Example 9) simulated a scenario where bacteria resided on a membrane that was not being worn by a person. Therefore, the experimental conditions were set to match this scenario (no nutrients added, incubation at room temperature).

The current experiments addressed the more realistic scenario of fabrics being worn closely by humans. The human body acts as a reservoir, continuously supplying moisture, heat, and nutrients to microorganisms residing on the fabric through perspiration. Therefore, bacterial incubation on fabrics was performed according to AATCC Test Method 100-2004 at 37°C using nutrients.

Two types of samples were prepared. One type (conventional copper oxide fabric) consisted of a fabric containing 3 wt.% copper oxide in polyester fiber. The other type (accelerated copper oxide fabric) contained 2.4 wt.% copper oxide + TST in polyester fiber of the same size as the above fibers, with copper oxide accounting for 99.5 wt.% and TST accounting for 0.5 wt.%.

All fabrics were sterilized before use by soaking in 70% ethanol for 10 minutes and then dried overnight in a sterile environment. Bacteria (E. coli) were grown overnight in LB medium (10% tryptone, 5% yeast extract, 10% NaCl (wt.%)) and diluted to approximately 10 ⁵ CFU/ml using fresh autoclaved LB medium. Treated fabrics and controls were then saturated with 1 ml of the bacterial culture medium, placed in a sealed sterile jar, and incubated at 37°C for the specified time.

Bacteria were extracted from the fabric using fresh LB medium, and 200 μl was then inoculated on LB agar Petri dishes overnight to allow colony growth.

The effective reduction in bacterial population on each fabric was compared to its own control, an untreated fabric of the same weave and size. Each experiment was performed in duplicate and averaged. The experimental results are presented in Tables 4-6.

Table 4: Effective reduction of bacterial population when using fabrics comprising a single oxidation state oxide or a combination of mixed oxidation state oxides and a single oxidation state oxide measured over a period of 0-40 min

Table 5: Effective reduction of bacterial population when using fabrics comprising a single oxidation state oxide or a combination of mixed oxidation state oxides and a single oxidation state oxide measured over a period of 0-180 min

Table 6: Effective reduction of bacterial population when using fabrics comprising a combination of mixed oxidation state oxides and single oxidation state oxides measured over a period of 0-300 min

The bacterial proliferation inhibition performance of the tested fabrics is also presented in Figures 5A-5C and 6A-6B.

The results showed that fabrics treated with copper oxide and TST inhibited bacterial growth more effectively than copper oxide alone, especially over longer time scales than 180 min.

Example 11: Proliferation Inhibition on Blended Polymer-Cotton Fabrics Using AATCC Test Method 100-2004 System test

Two types of samples were prepared. One type (conventional copper oxide fabric) comprised a combination of polyester and cotton fibers, wherein the polymer fibers contained 3 wt.% copper oxide relative to the total weight of the polymer fibers. The copper oxide in the sample was 97.7% pure, with 2.3% impurities. The fibers were extruded in the same manner as conventional short-cut polyester fibers and then blended with cotton, resulting in a final treated fiber loading of 30% copper oxide-impregnated fiber/70% cotton. A 24/1s twisted ring-spun combed cotton yarn was formed for weaving. The yarn was then knitted into a fabric weighing 150 grams per square meter.

Another type (accelerated copper oxide fabric) comprises a combination of polyester and cotton fibers, wherein the polymer fibers are impregnated with 3 wt.% copper oxide + TST, with copper oxide accounting for 99.5 wt.% and TST accounting for 0.5 wt.%. The fibers are extruded in the same manner as conventional short-cut polyester fibers and then blended with cotton to a final treated fiber loading of 30% copper oxide and TST accelerator-impregnated fibers/70% cotton, forming a 24/1s twisted ring-spun combed cotton yarn for weaving. The yarn is then knitted into a fabric weighing 150 grams per square meter.

The two types of samples were tested against a control fabric using AATCC Test Method 100-2004 (Quantitative) as described in Example 10. The control comprised 30% untreated polyester/70% cotton fabric weighing approximately 150 grams per square meter. None of the fabrics were dyed. All fabrics were sterilized prior to use by soaking in 70% ethanol for 10 minutes and then drying overnight in a sterile environment.

The results of the bacterial proliferation inhibition test are presented in Figure 7. It is clearly shown that the polymer-cotton blend fabric comprising a combination of mixed oxidation state oxides and single oxidation state oxides has a higher antimicrobial activity than the same fabric comprising a single oxidation state oxide alone.

Example 12: Detection of mixed oxidation state oxides in polymeric materials

A portion of the textile or fiber or molded or cast product is placed in an oven and heated to a temperature that allows the polymer to be carbonized into ash, but below the melting temperature of the metal oxide. The ash is then placed in an X-ray diffraction system, which identifies the crystalline structure of the crystals and can therefore detect the presence of metal oxide powder in the sample in addition to the carbon ash.

Although the present invention has been described in detail, it will be appreciated by those skilled in the art that many changes and modifications may be made. Therefore, the present invention should not be construed as being limited to the specifically described embodiments. Instead, the scope, spirit, and concept of the present invention will be more readily understood by reference to the appended claims.

Claims (24)

1. A material with antimicrobial properties, the material comprising a polymer incorporating a synergistic combination of at least two metal oxide powders, the combination comprising a mixed oxide of a first metal and a single oxide of a second metal, the powders being substantially uniformly incorporated into the polymer, wherein the powders have substantially different specific gravities and substantially similar bulk densities, and wherein, upon exposure of the material to moisture, the ions of the metal oxides undergo ionic contact. 2. The material according to claim 1, wherein the mixed oxide is selected from silver tetroxide (Ag ₄ O ₄ ), Ag ₂ O ₂ , copper tetroxide (Cu ₄ O ₄ ), Cu oxide (I,III), Cu oxide (II,III) and combinations thereof. 3. The material according to claim 1, wherein the single oxide state is selected from copper oxide, silver oxide, zinc oxide, and combinations thereof. 4. The material according to claim 1, wherein the synergistic combination of the at least two metal oxide powders comprises copper oxide and silver tetroxide. 5. The material according to any one of claims 1 to 4, wherein the mixed oxide accounts for at most 15 wt.% of the total weight of the synergistic combination of the at least two metal oxide powders, and wherein the mixed oxide is present in the synergistic combination in a detectable amount. 6. The material according to any one of claims 1 to 4, wherein the metal oxide powders having substantially similar bulk densities comprise particles with an average particle size inversely proportional to their specific gravity. 7. The material according to any one of claims 1 to 4, wherein the metal oxide powders having substantially similar bulk densities comprise particles having substantially similar average particle sizes, and wherein the particles are coated with a coating of thickness proportional to the specific gravity of the metal oxide particles. 8. The material according to any one of claims 1 to 4, wherein the polymer is selected from polyamides, polyesters, acrylic polymers, polyolefins, polysiloxanes, polyvinyl acetate, starch-based polymers, cellulose-based polymers, dispersions and mixtures thereof. 9. The material according to any one of claims 1 to 4, wherein the combined weight of the at least two metal oxide powders accounts for 0.25 wt.% to 50 wt.% of the total weight of the material. 10. The material according to any one of claims 1 to 4, wherein it is in the form of a masterbatch. 11. The material according to claim 10, wherein the combined weight of the at least two metal oxide powders accounts for 0.5 wt.% to 50 wt.% of the total weight of the masterbatch. 12. The material according to claim 1, wherein it is in the form of fiber, textile, film or foil. 13. The material according to claim 1, wherein it is in the form of yarn or fabric. 14. The material according to any one of claims 12 and 13, wherein the combined weight of the at least two metal oxide powders accounts for 0.5 wt.% to 15 wt.% of the total weight of the material. 15. The material according to any one of claims 1 to 4, further comprising natural fibers selected from cotton, silk, wool, flax, and combinations thereof. 16. The material according to claim 15, wherein the combined weight of the at least two metal oxide powders accounts for 0.25 wt.% to 5 wt.% of the total weight of the material. 17. The material according to any one of claims 1 to 4, wherein it is in the form of products selected from: clothing articles, bedding textiles, laboratory or hospital textiles, laboratory equipment, hospital equipment, medical textiles, personal hygiene products, packaging or wrapping materials, caps for consumer products, food equipment, contraceptive devices, agricultural products or bathroom products. 18. The material according to any one of claims 1 to 4, wherein the polymer is selected from polymers that are extruded, molded, cast, or 3D printed. 19. The material according to any one of claims 1 to 4, which is used to antagonize or inhibit the activity of microorganisms or microorganisms selected from: Gram-positive bacteria, Gram-negative bacteria, fungi, parasites, molds, spores, yeasts, protozoa, algae, mites and viruses. 20. A method for preparing a material with antimicrobial properties, the material comprising a polymer incorporating a synergistic combination of at least two metal oxide powders, the combination comprising a mixed oxide of a first metal and a single oxide of a second metal, the powders being substantially uniformly incorporated into the polymer, wherein the powders have substantially different specific gravities and substantially similar bulk densities, and undergo ionic contact upon exposure to moisture, the method comprising the steps of: a. Processing the at least two metal oxide powders to obtain substantially similar bulk densities; and b. Mix the powder with at least one polymer. 21. The method of claim 20, wherein step b. comprises producing a masterbatch comprising the metal oxide powder and the carrier polymer. 22. The method according to any one of claims 20 and 21, further comprising step c, said step c, comprising forming a product selected from fibers, textile products and non-textile polymer articles from the obtained mixture. 23. The method according to any one of claims 20 and 21, further comprising step c, which includes forming a product selected from yarns and fabrics from the obtained mixture. 24. The method according to any one of claims 20 and 21, further comprising step c, which includes forming a product selected from films and foils from the obtained mixture.