Patent Application
20210352907
In at least one aspect, the present invention is related to antibacterial coatings and, in particular, to multilayer coatings having antibacterial properties.
Generally, copper and copper alloys with over 60% copper have been shown to have antimicrobial properties. However, copper and copper alloys are relatively soft and prone to oxidation/corrosion. Some research supports the theory that the efficacy of copper alloys against microbes scales with the tendency to corrode. Therefore, it is believed that the tendency to corrode correlates with the effectiveness of killing microbes.
Oxides of copper include cuprous oxide (Cu2O, cuprite) and cupric oxide (CuO, tenorite). Both are semiconductors and transition metal oxides (TMO), thin films of which have a variety of uses, including electronic devices, catalysts, sensors, and solar cell absorbers. Oxides of copper tend to be more chemically stable and harder than copper metal.
Accordingly, there is a need for antimicrobial coatings with improved corrosion resistance and durability.
In at least one aspect, a coated substrate includes a base substrate and a base layer disposed over the base substrate. Typically, the base layer is composed of a component selected from the group consisting of zirconium carbonitrides, zirconium oxycarbides, titanium carbonitrides, titanium oxycarbides, chromium oxide (e.g., Cr2O3), chromium nitride, chromium carbonitride, diamond-like carbon, chromium metal, and combinations thereof. One or more copper-containing antimicrobial layers are disposed over the base layer such that each of the one or more copper-containing antimicrobial layers includes copper atoms in the +1 oxidation state and/or the +2 oxidation state. Advantageously, the copper containing antimicrobial layers are found to have improved corrosion resistance and durability.
In another aspect, a method for forming the coated substrate set forth herein is provided. The method includes a step of providing a base substrate. A base layer is deposited over the base substrate. The base layer can be composed of a component selected from the group consisting of zirconium carbonitrides, zirconium oxycarbides, titanium carbonitrides, titanium oxycarbides, diamond-like carbon, chromium nitride, chromium carbonitride, chromium metal, and combinations thereof. One or more copper-containing antimicrobial layers are deposited over the base layer. Characteristically, each of the one or more copper-containing antimicrobial layers includes copper atoms in a +1 oxidation state and/or a +2 oxidation state.
Reference will now be made in detail to presently preferred compositions, embodiments and methods of the present invention, which constitute the best modes of practicing the invention presently known to the inventors. The Figures are not necessarily to scale. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. Therefore, specific details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for any aspect of the invention and/or as a representative basis for teaching one skilled in the art to variously employ the present invention.
It is also to be understood that this invention is not limited to the specific embodiments and methods described below, as specific components and/or conditions may, of course, vary. Furthermore, the terminology used herein is used only for the purpose of describing particular embodiments of the present invention and is not intended to be limiting in any way.
It must also be noted that, as used in the specification and the appended claims, the singular form “a,” “an,” and “the” comprise plural referents unless the context clearly indicates otherwise. For example, reference to a component in the singular is intended to comprise a plurality of components.
The term “comprising” is synonymous with “including,” “having,” “containing,” or “characterized by.” These terms are inclusive and open-ended and do not exclude additional, unrecited elements or method steps.
The phrase “consisting of” excludes any element, step, or ingredient not specified in the claim. When this phrase appears in a clause of the body of a claim, rather than immediately following the preamble, it limits only the element set forth in that clause; other elements are not excluded from the claim as a whole.
The phrase “consisting essentially of” limits the scope of a claim to the specified materials or steps, plus those that do not materially affect the basic and novel characteristic(s) of the claimed subject matter.
With respect to the terms “comprising,” “consisting of,” and “consisting essentially of,” where one of these three terms is used herein, the presently disclosed and claimed subject matter can include the use of either of the other two terms.
The phrase “composed of” means “including” or “comprising.” Typically, this phrase is used to denote that an object is formed from a material.
It should also be appreciated that integer ranges explicitly include all intervening integers. For example, the integer range 1-10 explicitly includes 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Similarly, the range 1 to 100 includes 1, 2, 3, 4 . . . 97, 98, 99, 100. Similarly, when any range is called for, intervening numbers that are increments of the difference between the upper limit and the lower limit divided by 10 can be taken as alternative upper or lower limits. For example, if the range is 1.1 to 2.1 the following numbers 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, and 2.0 can be selected as lower or upper limits.
In the examples set forth herein, concentrations, temperature, and reaction conditions (e.g., pressure, pH, flow rates, etc.) can be practiced with plus or minus 50 percent of the values indicated rounded to or truncated to two significant figures of the value provided in the examples. In a refinement, concentrations, temperature, and reaction conditions (e.g., pressure, pH, flow rates, etc.) can be practiced with plus or minus 30 percent of the values indicated rounded to or truncated to two significant figures of the value provided in the examples. In another refinement, concentrations, temperature, and reaction conditions (e.g., pressure) can be practiced with plus or minus 10 percent of the values indicated rounded to or truncated to two significant figures of the value provided in the examples.
The term “metal” as used herein means an alkali metal, an alkaline earth metal, a transition metal, a lanthanide, an actinide, or a post-transition metal.
The term “alkali metal” means lithium, sodium, potassium, rubidium, cesium, and francium.
The “alkaline earth metal” means a chemical elements in group 2 of the periodic table. The alkaline earth metals include beryllium, magnesium, calcium, strontium, barium, and radium.
The term “transition metal” means an element whose atom has a partially filled d sub-shell, or which can give rise to cations with an incomplete d sub-shell. Examples of transition metals includes scandium, titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper, yttrium, zirconium, niobium, molybdenum, technetium, ruthenium, rhodium, palladium, silver, hafnium, tantalum, tungsten, rhenium, osmium, iridium, platinum, and gold.
The term “lanthanide” or lanthanoid series of chemical elements” means an element with atomic numbers 57-71. The lanthanides metals includes lanthanum, cerium, praseodymium, samarium, europium, gadolinium neodymium, promethium, terbium, dysprosium, holmium, erbium, thulium, ytterbium, or lutetium.
The term “actinide” or “actinide series of chemical elements” means chemical elements with atomic numbers from 89 to 103. Examples of actinides includes actinium, thorium, protactinium, uranium, neptunium, and plutonium.
The term “post-transition metal” means gallium, indium, tin, thallium, lead, bismuth, zinc, cadmium, mercury, aluminum, germanium, antimony, or polonium.
Throughout this application, where publications are referenced, the disclosures of these publications in their entireties are hereby incorporated by reference into this application to more fully describe the state of the art to which this invention pertains.
Abbreviations:
“PVD” means physical vapor deposition.
“HIPIMS” means high-power impulse magnetron sputtering.
In one embodiment, a coated substrate that includes a base substrate and a base layer disposed over the base substrate is provided. In this context “base substrate” means the substrate to be coated by the methods herein. Characteristically, the base layer is a zirconium-containing base layer and/or a titanium-containing base layer. In a refinement, the base layer is composed of a component selected from the group consisting of zirconium carbonitrides, zirconium oxycarbides, titanium carbonitrides, titanium oxycarbides, and combinations thereof. One or more (i.e., or a plurality of) copper-containing antimicrobial layers are disposed over the base layer such that each of the one or more copper-containing antimicrobial layers includes copper atoms in the +1 oxidation state and/or the +2 oxidation state. In a refinement, copper-containing antimicrobial layers contact the base layer (i.e., one of the one or more copper-containing antimicrobial layers contact the base layer). The one or more copper-containing antimicrobial layers can be the same (e.g., composed of the same material) or different (e.g., composed of the different materials). Typically, adjacent layers are composed of different compositions and/or have different thicknesses. Advantageously, the copper containing antimicrobial layers are found to have improved corrosion resistance and durability.
Each of the copper-containing antimicrobial layers independently can include copper metal (i.e., copper atoms in the zero oxidation state), copper oxides, copper nitrides, copper oxides containing carbon atoms, and combinations thereof. The incorporation of oxygen and/or carbon and/or nitrogen into copper layers improves corrosion and increases durability. In one refinement, each of the one or more copper-containing antimicrobial layers includes CuOx, where x is from 0.2 to 1.2. In another refinement, the one or more copper-containing antimicrobial layers can include CuOaNb, where a is from 0.0 to 1.2 and b, is from 0.01 to 0.4. In still another refinement, the one or more copper-containing antimicrobial layers can include CuOcCd, where c is from 0.0 to 1.2 and d, is from 0.01 to 0.4. In a variation, each copper-containing antimicrobial layers can independently include any combination of copper metal, CuOx, CuOaNb, and CuOcCd; Therefore, each copper-containing antimicrobial layer can independently include a combination of copper metal, CuOx, CuOaNb, and CuOcCd or a combination of copper metal and CuOx or a combination of copper metal and CuOaNb; a mixture of copper metal and CuOcCd or a combination of copper metal, CuOx, and CuOaNb or a combination of copper metal, CuOx and CuOcCd or a combination of copper metal, CuOaNb, and CuOcCd or a combination of CuOx, CuOaNb, and CuOcCd or a combination of CuOx and CuOaNb or a combination of CuOaNb, and CuOcCd or a combination of CuOx, CuOaNb, and CuOcCd.
In a variation, the base layer includes zirconium or titanium, carbon and nitrogen where zirconium is present in an amount of at least 50 mole percent with each of the carbon and nitrogen present in an amount of at least 0.02 and 0.1 mole percent, respectively. In a refinement, the base layer includes a compound having the following formula:
M1-x-yCxNy
where M is zirconium or titanium and x is 0.0 to 0.3 and Y is 0.1 to 0.5. In a refinement, x is 0.0 to 0.2 and y is 0.2 to 0.3. In another refinement, x is at least in increasing order of preference 0.0, 0.02, 0.03, 0.04, 0.05, 0.07, or 0.09 and at most in increasing order of preference, 0.5, 0.4, 0.3, 0.25, 0.2, 0.15, or 0.11. Similarly, in this refinement, y is at least in increasing order of preference 0.1, 0.15, 0.2, 0.25, 0.27, or 0.29 and at most in increasing order of preference, 0.6, 0.5, 0.40, 0.35, 0.33, or 0.31. In a further refinement, the base layer includes zirconium carbonitride described by Zr0.60C0.10N0.30.
In a variation, the base layer includes zirconium or titanium, carbon, and oxygen where zirconium is present in an amount of at least 50 mole percent with each of the carbon and oxygen present in an amount of at least 0.02 and 0.1 mole percent, respectively. In a refinement, the base layer includes a compound having the following formula:
M1-x-yOxCy.
where M is zirconium or titanium and x is 0.1 to 0.4 and y is 0.5 to 0.2. In a further refinement, the base layer includes zirconium oxycarbide described by Zr0.50O0.35C0.15.
In another variation, the one or more copper-containing antimicrobial layers includes an atom selected from the group consisting of a metal other than copper, carbon, nitrogen, and combinations thereof. In a refinement, the one or more copper-containing antimicrobial layers include an atom selected from the group consisting of a transition metal other than copper, carbon, nitrogen, and combinations thereof. In still another refinement, the one or more copper-containing antimicrobial layers includes an atom selected from the group consisting of a zirconium, titanium, tin, and combinations thereof. Typically, the atom is present in an amount from about 1 mol percent to about 60 mole percent of the total moles of atoms in the one or more copper-containing antimicrobial layers. In a refinement, the atom is present in an amount of at least, in increasing order of preference, 0.1 mol percent, 0.5 mol percent, 1 mol percent, 3 mol percent, or 5 mol percent of the total moles of atoms in the one or more copper-containing antimicrobial layers. In another refinement, the atom is present in an amount of equal to or less than, in increasing order of preference, 70 mole percent, 60 mole percent, 50 mole percent, 40 mole percent, 30 mole percent, 20 mole percent, or 10 mole percent of the total moles of atoms in the one or more copper-containing antimicrobial layers.
The base substrate used herein can virtually include any solid substrate. Examples of such substrates include metal substrates, plastic substrates, and glass substrates. In one variation, the base substrate is not glass. In some variations, the base substrate is pre-coated with a metal adhesion layer. Such metal adhesion layers include metals such as chromium, nickel, tungsten, zirconium, and combinations thereof. Although any thickness for the adhesion layer can be used, useful thicknesses are from 100 nm to 0.2 microns.
Another feature of the present invention is the ability to visually detect when the top copper-containing antimicrobial layer has worn. In this context, the top copper-containing antimicrobial layer is furthest from the base substrate and exposed to ambient. Advantageously, the coated substrate is such that the color of the top copper-containing antimicrobial layer has a visually perceivable color that is different from the color of the layer immediately below it. For a coated substrate having a single copper-containing antimicrobial layer, the layer immediately below is the base layer. When a plurality of copper-containing antimicrobial layers are present, the layer immediately below the top copper-containing antimicrobial layer is another copper-containing antimicrobial layer. The color of each of the base layer and copper-containing antimicrobial layers can independently be changed by adjusting the thicknesses and or stoichiometries of the layer. The top copper-containing antimicrobial layer and the layer immediately below the top copper-containing antimicrobial layer (as well as the substrate and other layers) can be characterized by Lab color space coordinates L*, a*, and b* relative to CIE standard illuminant D50. In a refinement, at least one of Lab color space coordinates L*, a*, and b* relative to CIE standard illuminant D50 of the top copper-containing antimicrobial layer differs from that of the layer immediately below the top copper-containing antimicrobial layer by at least in increasing order of preference, 5%, 10%, 15%, 20%, 25% or 50%. In another refinement, each of the Lab color space coordinates L*, a*, and b* relative to CIE standard illuminant D50 of the top copper-containing antimicrobial layer differ from those of the layer immediately below the top copper-containing antimicrobial layer by at least in increasing order of preference, 5%, 10%, 15%, 20%, 25% or 50%.
Referring to
Details for the base substrate, base layer, and the one or more one or more copper-containing antimicrobial layers are the same as set forth above. For example, one or more of each of the copper-containing antimicrobial layers independently includes a component selected from the group consisting of copper metal, copper oxides, copper nitrides, copper oxides containing carbon atoms, and combinations thereof. In a refinement as set forth above, the one or more copper-containing antimicrobial layers include an atom selected from the group consisting of a transition metal other than copper, carbon, nitrogen, and combinations thereof. In another refinement, as set forth above, the base layer has a thickness from about 100 to 500 nm, and each copper-containing antimicrobial layer has a thickness from about 50 to 3000 nm.
Each of the base layer and the copper-containing antimicrobial layers can be deposited by any number of thin film deposition techniques known in the coatings art. In particular, these layers can be deposited by PVD techniques. Examples of PVD techniques include, but are not limited to, cathodic arc deposition, electron-beam physical vapor deposition, evaporation, pulsed laser deposition, and sputtering.
The following examples illustrate the various embodiments of the present invention. Those skilled in the art will recognize many variations that are within the spirit of the present invention and scope of the claims.
A vacuum thin film deposition chamber is pumped down to a pressure of 8.0×10−5 Torr. Inside the chamber, stainless steel panels are mounted on a fixture near the wall and facing a centrally located cylindrical arc Copper cathode. An ion etch surface preparation is carried out by backfilling with Argon gas to a pressure of 25.0 mTorr and a bias voltage of −500V is applied to parts. This step lasts 5 minutes after which the Argon gas is shut off. The chamber is backfilled by Oxygen to a pressure of 1.0 mTorr and a substrate bias of −50V is applied. A Copper Oxide adhesion layer is applied to the panels by striking an arc on the arc cathode at a current of 350 A. This step lasts 5 minutes to build a layer of 140 nm thick Copper Oxide. A final coating layer comprised of a Copper Nitride is applied by continuing to run the arc on the Cu target but turning off the Oxygen and adding Nitrogen that flows at 125 sccm for a composition of approximately CuN0.20. This layer is built up to 740 nm in 20 minutes at which point the Copper arc cathode is turned off and the Nitrogen gas is shut off. The resulting film is a total of 880 nm thick.
(Multilayer Coating with a CuOx Topcoat)
A vacuum thin film deposition chamber is pumped down to a pressure of 8.0×10−5 Torr. On a carousel inside the chamber, stainless steel panels are mounted on racks that rotate in a 2-axis planetary motion between two wall mounted magnetron sputtering cathodes. An ion etch surface preparation is carried out by backfilling with Argon gas to a pressure of 30.0 mTorr and a bias voltage of −300V for 0.5 min followed by −600V for 4 min is applied to parts. A Zirconium metal adhesion layer is applied to the panels by powering Zirconium sputtering magnetron cathode to 10 kW. For this, the chamber is backfilled by Argon to a pressure of 3.0 mTorr and a substrate bias of −75V is applied. This step lasts 2 minutes to build a layer of 50 nm thick Zr metal. A second coating layer comprised of a Zirconium Oxide, is applied by continuing to run sputter magnetron on the Zr target but adding Oxygen gas at flows of 50 sccm for a composition of approximately Zr0.60O0.40. This layer is built up to 30 nm in 2 minutes at which point the Zr cathode is turned off. The Oxygen flow is turned up to 85 sccm and the Argon continues to flow to maintain a pressure of 3.0 mTorr. A voltage of 560V is applied to the sputtering magnetron Copper cathode for a duration of 10 minutes to result in a composition of approximately CuO0.82 with a layer thickness of 1130 nm. The resulting film is a total of 1210 nm thick.
(Multilayer Coating with a CuZryOx Topcoat)
A vacuum thin film deposition chamber is pumped down to a pressure of 8.0×10−5 Torr. On a carousel inside the chamber, stainless steel panels are mounted on racks that rotate in a 2-axis planetary motion between two wall mounted magnetron sputtering cathodes; both with shutters. One of the cathodes is Zirconium while the other cathode is an alloy of 50 at % Copper and 50 at % Zirconium. An ion etch surface preparation is carried out by backfilling with Argon gas to a pressure of 30.0 mTorr and a bias voltage of −500V for 5 min is applied to parts. A Zirconium metal adhesion layer is applied to the panels by powering the Zirconium sputtering magnetron cathode to 15 kW and opening the shutter. For this, the chamber is backfilled by Argon to a pressure of 3.0 mTorr and a substrate bias of −75V is applied. This step lasts 2 minutes to build a layer of 100 nm thick Zr metal on the panels. A second coating layer comprised of a Zirconium Nitride is applied by continuing to run the sputter magnetron on the Zirconium cathode but adding a flow of Nitrogen gas for a layer composition of approximately ZrN. During this and the subsequent step, the total flow maintains a pressure of 3.0 mTorr. This layer is built up to 30 nm over a duration of 1 minute. The Zirconium cathode is then powered off and the shutter is closed. The shutter for the alloy cathode is then opened. The alloy cathode is powered to 6 kW for duration of 4 minutes to result in a composition of approximately CuZr0.6O2.4 with a layer thickness of 490 nm. The resulting film is a total of 620 nm thick.
Table 1 provides the physical properties of copper samples as well as the atomic percentages of copper, oxygen, nitrogen, and zirconium in the samples. Table 1 also provides color properties of the samples.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
This application claims the benefit of U.S. provisional application Ser. No. 63/024,096 filed May 13, 2020, the disclosure of which is hereby incorporated in its entirety by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 63024096 | May 2020 | US |
