WO2021260371A1 - Antimicrobial and/or antiviral mirror - Google Patents

Antimicrobial and/or antiviral mirror Download PDF

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Publication number
WO2021260371A1
WO2021260371A1 PCT/GB2021/051588 GB2021051588W WO2021260371A1 WO 2021260371 A1 WO2021260371 A1 WO 2021260371A1 GB 2021051588 W GB2021051588 W GB 2021051588W WO 2021260371 A1 WO2021260371 A1 WO 2021260371A1
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WO
WIPO (PCT)
Prior art keywords
antimicrobial
antiviral
layer
mirror
mirror according
Prior art date
Application number
PCT/GB2021/051588
Other languages
French (fr)
Inventor
Tim MCKITTRICK
Stephen Emil WEIDNER
Rory BACK
Neil Mcsporran
Srikanth Varanasi
Original Assignee
Pilkington Group Limited
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Pilkington Group Limited filed Critical Pilkington Group Limited
Priority to EP21737750.6A priority Critical patent/EP4168364A1/en
Publication of WO2021260371A1 publication Critical patent/WO2021260371A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/06—Surface treatment of glass, not in the form of fibres or filaments, by coating with metals
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J21/00—Catalysts comprising the elements, oxides, or hydroxides of magnesium, boron, aluminium, carbon, silicon, titanium, zirconium, or hafnium
    • B01J21/06—Silicon, titanium, zirconium or hafnium; Oxides or hydroxides thereof
    • B01J21/063—Titanium; Oxides or hydroxides thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/38—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of noble metals
    • B01J23/48—Silver or gold
    • B01J23/50—Silver
    • B01J35/39—
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/0009—Use of binding agents; Moulding; Pressing; Powdering; Granulating; Addition of materials ameliorating the mechanical properties of the product catalyst
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/02—Impregnation, coating or precipitation
    • B01J37/0215—Coating
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/22—Surface treatment of glass, not in the form of fibres or filaments, by coating with other inorganic material
    • C03C17/23—Oxides
    • C03C17/245—Oxides by deposition from the vapour phase
    • C03C17/2456—Coating containing TiO2
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
    • C03C17/3411—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions with at least two coatings of inorganic materials
    • C03C17/3417—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions with at least two coatings of inorganic materials all coatings being oxide coatings
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
    • C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
    • C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
    • C03C17/3602—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer
    • C03C17/3644—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer the metal being silver
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C17/00—Surface treatment of glass, not in the form of fibres or filaments, by coating
    • C03C17/34—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions
    • C03C17/36—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal
    • C03C17/3602—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer
    • C03C17/3657—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer the multilayer coating having optical properties
    • C03C17/3663—Surface treatment of glass, not in the form of fibres or filaments, by coating with at least two coatings having different compositions at least one coating being a metal the metal being present as a layer the multilayer coating having optical properties specially adapted for use as mirrors
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
    • G02B1/18—Coatings for keeping optical surfaces clean, e.g. hydrophobic or photo-catalytic films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/72—Copper
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2217/00—Coatings on glass
    • C03C2217/70—Properties of coatings
    • C03C2217/71—Photocatalytic coatings
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2218/00—Methods for coating glass
    • C03C2218/30—Aspects of methods for coating glass not covered above
    • C03C2218/365—Coating different sides of a glass substrate
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/08—Mirrors

Definitions

  • the present invention relates to an antimicrobial and/or antiviral mirror, a method for producing an antimicrobial and/or antiviral mirror, an article comprising an antimicrobial and/or antiviral mirror, and to the use of an antimicrobial and/or antiviral mirror.
  • microbes include bacteria, viruses and fungi.
  • the present invention is particularly related to mirrors which may be antibacterial, antiviral and antifungal in nature, especially mirrors which are antiviral and/or antibacterial.
  • the present invention relates to an antimicrobial and/or antiviral mirror comprising a sheet of glazing material and a photocatalytic layer, a method of producing same, and to the use of same to reduce the presence of microbes, on a surface.
  • microbes include bacteria, viruses and fungi.
  • One way in which microbes are transmitted is by “surface transmission”. This is where an individual interacts with a surface that has previously been seeded with microbes, for example by previous interaction with the surface by infectious individuals.
  • Transparent and semi-transparent surfaces are commonly found in environments which are shared by multiple individuals. As such, transparent and semi transparent surfaces may act as a vector for the transmission of microbes especially bacteria and viruses. This is particularly a problem in spaces which may be occupied by large numbers of people in succession, such as toilets, corridors, hospital rooms, shops and workplaces.
  • a surface may not be sufficiently inhospitable to microbes, and traditional cleaning practices and products may not successfully remove sufficient levels of microbes.
  • One method of disinfection is by cleaning surfaces using a germicidal cleaner, such as a bleach.
  • a germicidal cleaner such as a bleach
  • the use of bleach as a disinfectant may give rise to similar problems as stated above in respect of cleaning with a detergent, namely impaired appearance and performance of the substrate surface.
  • cleaning performed manually with a germicidal product can often be more damaging and corrosive to the surface.
  • germicidal cleaners may not sufficiently denature all microbes on the surface.
  • UV disinfection An alternative method of disinfecting surfaces is by UV disinfection.
  • UV light irradiation is used to denature microbes on a surface.
  • UV is the term given to light in the wavelength range 100 to 400nm.
  • UV light is commonly divided into UVA (320 to 400 nm), UVB (280 to 320 nm), and UVC (100 to 280 nm). UV light is particularly effective for disinfecting surfaces, as the light penetrates microbes and alters their DNA structure, impairing and preventing replication.
  • UV disinfection may be used in addition to disinfection with a germicidal cleaner.
  • the additional UV disinfection step further reduces the prevalence of microbes on the surface, therefore reducing the likelihood of infection due to contact with the surface.
  • An advantage of using UV disinfection in addition to disinfection with a germicidal cleaner is that this may allow the use of less corrosive cleaners, or may allow increased confidence that the surface is fully disinfected.
  • an antimicrobial and/or antiviral mirror comprising: a sheet of glazing material, wherein the sheet of glazing material comprises a first surface and a second surface; and a photocatalytic layer, wherein the photocatalytic layer is applied directly or indirectly to the first surface of the sheet of glazing material; and wherein the antimicrobial and/or antiviral mirror further comprises a visible light reflective layer applied directly or indirectly to the second surface.
  • photocatalytic layers which provide for example self-cleaning properties, may also provide an antimicrobial effect.
  • the photocatalytic layers may provide an antibacterial and/or antiviral effect.
  • the photocatalytic layer may comprise titanium oxide, preferably titanium oxide with a predominantly anatase crystal structure. More preferably, the photocatalytic layer comprises titanium oxide with greater than or equal to 50% anatase. It has been found that a photocatalytic layer comprising titanium oxide has excellent antimicrobial properties, especially when illuminated with UV light. Furthermore, it has been found that, following irradiation of the photocatalytic layer with UV light, an increased antimicrobial effect persists even in the absence of any light at all.
  • the photocatalytic layer has a photocatalytic activity of greater than 5 x 10 -3 cm 1 min 1 . More preferably the photocatalytic layer has a photocatalytic activity of greater than 1 x 10 2 cnr 1 min 1 . Even more preferably the photocatalytic layer has a photocatalytic activity of greater than 3 x 10 -2 cm -1 min -1 .
  • Photocatalytic activity for the purposes of this specification is determined by measuring the rate of decrease of the integrated absorbance of the infra-red absorption peaks corresponding to the C-H stretches of a thin film of stearic acid, formed on the coated substrate, under illumination by UV light from a UVA lamp having an intensity of about 32 W/m 2 at the surface of the coated substrate and a peak wavelength of 351 nm.
  • the stearic acid film may be formed on samples of the glasses, 7 to 8 cm square, by spin casting 20 pi of a solution of stearic acid in methanol (8.8 x 10 3 mol dm -3 ) on the coated surface of the glass at 2000 rpm for 1 minute. Infra red spectra may be measured in transmission, and the peak height of the peak corresponding to the C-H stretches (at about 2700 to 3000 cm 1 ) of the stearic acid film measured and the corresponding peak area determined from a calibration curve of peak area against peak height.
  • a suitable UVA lamp is a UVA-351 lamp (obtained from the Q-Panel Co., Cleveland, Ohio, USA) having a peak wavelength of 351 nm and an intensity at the surface of the coated glass of approximately 32 W/m 2
  • the photocatalytic activity is expressed in this specification as the rate of decrease of the area of the IR peaks (in units of cnr 1 min -1 ).
  • the photocatalytic layer meets the EN 1096-5-2016 standard test method and classification for the self-cleaning performances of coated glass surfaces.
  • the photocatalytic layer has a thickness of 50 nm or lower. More preferably, the photocatalytic layer has a thickness of 40 nm or lower.
  • the photocatalytic layer has a thickness of from 10 nm to 40 nm. More preferably, the photocatalytic layer has a thickness from 15 to 30 nm. Even more preferably, the photocatalytic layer has a thickness from 15 to 20 nm.
  • Particular microbes and viruses which may be denatured by the antimicrobial and/or antiviral mirror according to the present invention include for example but are not limited to: gram positive and gram negative bacteria, including for example Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA), and corona viruses including SARS-CoV-2.
  • MRSA methicillin-resistant Staphylococcus aureus
  • SARS-CoV-2 corona viruses including SARS-CoV-2.
  • the antimicrobial and/or antiviral mirror according to the present invention may reduce the survival of one or more microbes on one or more surfaces of the sheet glazing material, such as for example bacteria and/or viruses, compared to a non-coated sheet of the same glazing material.
  • the visible light reflective layer may comprises a metal layer.
  • the metal layer may comprise one or more of silver metal, chromium metal, tin metal, nickel metal, aluminium metal or a combination thereof.
  • the sheet of glazing material preferably comprises glass.
  • the sheet of glazing material may be a planar body that transmits at least 10% of incident visible light, or may be reversibly modified to transmit at least 10% of incident visible light.
  • the antimicrobial and/or antiviral mirror comprises a visible light reflective layer applied directly or indirectly upon the second surface which preferably comprises a metal layer and/or a metalloid layer.
  • the metal layer comprises one or more of silver metal, chromium metal, tin metal, nickel metal, aluminium metal or a combination thereof.
  • the visible light reflective layer comprises a metal layer.
  • the metal layer is preferably applied to the second surface of the sheet of glazing material.
  • the metal layer preferably forms a mirror layer.
  • the antimicrobial and/or antiviral mirror according to the present invention preferably comprises an encapsulation layer applied to the visible light reflective layer.
  • the encapsulating layer may be applied indirectly to the second surface of the sheet of glazing material, such that the metal mirror coating is between the encapsulating layer and the sheet of glazing material.
  • the encapsulating layer preferably protects the metal mirror coating from damage, tarnishing and corrosion.
  • the metal mirror coating has a thickness of from 100 nm to 1 cm. Thicker coatings are less cost effective, while thinner coatings may not be sufficiently opaque (non-transmissive). The thickness of the metal mirror coating should be sufficient to enable visible light to be mostly reflected rather than transmitted.
  • the metal mirror coating preferably has a thickness of from 20 nm to 100 nm.
  • the sheet of glazing material comprises glass.
  • the sheet of glazing material comprises flat glass.
  • the sheet of glazing material comprises float glass.
  • the sheet of glazing material comprises soda-lime silica float glass. Soda-lime silica float glass is particularly beneficial as it is widely available and cost effective. In addition, it may be coated using highly efficient online coating processes.
  • the glass is low-iron glass.
  • low-iron glass comprises less than 200 ppm by weight iron.
  • the sheet of glazing material comprises down-drawn or rolled glass.
  • the sheet of glazing material may comprise resin, such as polycarbonate.
  • the antimicrobial and/or antiviral mirror according to the present invention comprises a glass substrate
  • the glass substrate may preferably comprise alternative forms of glass such as for example but not limited to: borosilicate glass, rolled plate glass, ceramic glass, toughened glass, chemically strengthened glass, hallow glass or glass shaped for articles such as bottles, jars and medical containers.
  • the first surface comprises an alkali metal ion blocking under-layer between the surface of the substrate and the photocatalytic layer.
  • the first surface further comprises an alkali metal ion blocking layer, wherein the alkali metal blocking layer is located between the first surface of the sheet of glazing material and the photocatalytic layer.
  • the alkali metal ion blocking layer comprises silicon oxide.
  • the alkali metal ion blocking layer comprising silicon oxide has a thickness of from 15 to 40 nm, more preferably a thickness of between 25 and 35 nm.
  • the antimicrobial and/or antiviral mirror preferably further comprises an encapsulation layer applied to the visible light reflective layer.
  • the encapsulation layer preferably prevents damage or tarnishing of the visible light reflective layer.
  • the encapsulation layer comprises a paint layer.
  • the photocatalytic layer may comprise copper and/or silver.
  • the photocatalytic layer comprises copper and/or silver containing particles.
  • the particles are nanoparticles and/or microparticles.
  • a nanoparticle may be particle with a diameter less than 100 nm.
  • a microparticle may be a particle with a diameter less than 1000 nm.
  • the antimicrobial and/or antiviral mirror according to the present invention may further comprise an antimicrobial layer.
  • the antimicrobial layer is preferably applied to the sheet of glazing material such that the photocatalytic layer is located between the sheet of glazing material and the antimicrobial layer.
  • the antimicrobial layer is applied to the substrate such that the photocatalytic layer is between the antimicrobial layer and the substrate.
  • the antimicrobial layer comprises copper and/or silver.
  • the antimicrobial layer is in direct contact with the photocatalytic layer.
  • the antimicrobial layer is in the form of islands, such that at least a portion of the photocatalytic layer is exposed between the islands of the antimicrobial layer.
  • the ratio of the sum of the areas of the island portions to the sum of the area of exposed photocatalytic layer is from 0.01 to 0.20.
  • the diameter calculated by converting the average area of the island portion into a circle when observed along the cross-section of the antimicrobial layer is 1 to 20 nm.
  • the antimicrobial layer may comprise a matrix comprising particles of copper and/or silver.
  • the particles of copper and/or silver may be nanoparticles and/or microparticles.
  • Copper and silver metals are preferred as same act upon microbes, especially bacteria, by oligodynamic action which may cause complete inhibition of the microbe.
  • the antimicrobial and/or antiviral mirror according to the present invention demonstrates a log reduction of at least 3 against one of Staphylococcus aureus, SARS- CoV-2, E.coli, P. gingivitis, or S.mutans. More preferably, the antimicrobial and/or antiviral mirror according to the present invention demonstrates a log reduction of at least 4 against one of Staphylococcus aureus, SARS-CoV-2, E.coli , P. gingivitis, or S.mutans, more preferably greater than 5, and most preferably 6.
  • a method for producing an antimicrobial and/or antiviral mirror comprising the steps of: i) providing a sheet of glazing material with a first surface and a second surface; ii) applying a photocatalytic layer directly or indirectly to the first surface; and iii) applying a visible light reflective layer to the second surface.
  • the photocatalytic layer is applied by chemical vapour deposition. More preferably the photocatalytic layer is applied by chemical vapour deposition during the float glass production process, and is therefore an “online coating”.
  • “online coating” relates to the use of chemical vapour deposition coating beams during the float glass production process.
  • the photocatalytic layer is applied by chemical vapour deposition it may be possible to produce the antimicrobial substrate in large volumes.
  • the photocatalytic layer is applied by chemical vapour deposition and the photocatalytic layer comprises titanium oxide, a higher proportion of titanium oxide with a predominantly anatase crystal structure may result.
  • the photocatalytic layer is applied by chemical vapour deposition using a precursor gaseous mixture comprising TiCU.
  • Photocatalytic layers applied by chemical vapour deposition using precursor gaseous mixtures comprising TiCU provide a higher proportion of anatase crystal structure titanium oxide than alternative precursor mixtures.
  • the photocatalytic layer may be applied by physical vapour deposition.
  • Physical vapour deposition is also known as sputtering.
  • the photocatalytic layer may be formed by curing a liquid coating precursor.
  • liquid coating precursors include tetraorthoxysilicate (TEOS) and perhydropolysilazane (PHPS).
  • TEOS tetraorthoxysilicate
  • PHPS perhydropolysilazane
  • photocatalytic particles may be included in the precursor mixture.
  • Forming the photocatalytic layer from a liquid coating precursor may allow different properties to be imparted to the layer.
  • the visible light reflective layer preferably comprises a metal layer applied to the sheet of glazing material by chemical vapour deposition, physical vapour deposition, or wet deposition.
  • the visible light reflective layer is applied to the sheet of glazing material by a wet deposition technique selected from: curtain coating, spray coating, spin coating, roller coating, slot-die coating, or rod draw coating.
  • a wet deposition technique selected from: curtain coating, spray coating, spin coating, roller coating, slot-die coating, or rod draw coating.
  • the visible light reflecting layer comprises a silver containing mirror layer or a chromium containing mirror layer.
  • the visible light reflective layer is a silver mirror layer.
  • the silver mirror layer is formed by curtain coating.
  • the silver mirror layer may be formed by alternative coating methods, including draw coating, spray coating and roll coating.
  • the visible light reflecting layer is a chromium containing mirror layer deposited by physical vapour deposition.
  • the visible light reflecting layer comprises: a silver containing mirror layer deposited by curtain coating; or a chromium containing mirror layer deposited by physical vapour deposition.
  • an antimicrobial and/or antiviral article comprising an antimicrobial and/or antiviral mirror according to the first aspect of the invention or produced by the method according to the second aspect of the invention.
  • an antimicrobial and antiviral mirror according to the first aspect of the invention or produced according to the second aspect of the invention, in a glazing frame, wall, bulkhead, blind, and/or door, wherein the antimicrobial and/or antiviral mirror is installed to allow the photocatalytic layer to face towards an external environment.
  • an antimicrobial and antiviral mirror according to the fourth aspect of the present invention further comprises the steps of irradiating the antimicrobial substrate with UV light from a UV light source for between 1 and 20 minutes.
  • UV light is electromagnetic radiation with a wavelength from 30 nm to 400 nm.
  • the UV light has a peak wavelength above 200 nm, more preferably above 220 nm, even more preferably above 250 nm.
  • the peak wavelength of light is the wavelength with the highest intensity in the light spectrum.
  • the peak wavelength of UV light is the wavelength with the highest intensity in the UV spectrum of 10 to 400 nm.
  • the UV light is activated using an automated sensor process or a timer.
  • an automated sensor process may include a sensor device for sensing parameter information, a communication system for relaying the parameter information to a computational device which determines a response.
  • the UV light source is a mobile UV light source.
  • the mobile UV light source may be actuated between a position where light from the UV light source may impinge upon the antimicrobial substrate, and a position in which light from the UV light source does not impinge upon the antimicrobial substrate.
  • the mobile UV light source is attached to a robotic device.
  • the robotic device is: an actuating arm; a wheeled, legged or tracked mobile carrier; or a retracting arm.
  • an antimicrobial and/or antiviral mirror according to the present invention further comprises a cleaning step, preferably wherein the antimicrobial and/or antiviral mirror is cleaned with a cleaning product, preferably a detergent and/or a germicidal cleaning product.
  • a cleaning product preferably a detergent and/or a germicidal cleaning product.
  • the cleaning step is an automated cleaning step, wherein the antimicrobial substrate is cleaned using sprayers, air knives and/or wipers.
  • the cleaning step may be a manual cleaning step.
  • Figure 1 illustrates a cross sectional view through an antimicrobial substrate according to a first embodiment of the present invention.
  • Figure 2 illustrates the Colony Reduction % of a coated comparative example compared to an uncoated comparative example.
  • an antimicrobial substrate 10 as depicted in Figure 1 , comprising a sheet of glazing material 1 and a photocatalytic layer 2, wherein the sheet of glazing material 1 comprises a first surface 1a and a second surface 1b, and wherein the photocatalytic layer 2 is applied to the first surface 1a.
  • the photocatalytic layer 2 may be directly applied to the first surface 1a.
  • the photocatalytic layer 2 may be indirectly applied to the first surface 1a.
  • an ion migration blocking layer may be located between the photocatalytic layer 2 and the sheet of glazing material 1.
  • the antimicrobial substrate 10 further comprises a visible light reflective layer 3 applied to the second surface 1b.
  • the visible light reflective layer 3 may be directly or indirectly applied to the second surface 1 b, provided that any intervening layers are at least partially visible light transmissive.
  • a low-iron glass is used as the sheet of glazing material, to increase the transmission of visible light through the sheet of glazing material and thereby increase the amount of visible light reflected.
  • the visible reflecting layer 3 comprises metal and the photocatalytic layer 2 comprises titanium oxide.
  • the metal comprises silver metal, chromium metal, aluminium metal, tin metal, nickel metal or a combination thereof. It is also preferred that the visible light reflecting metal layer 3 is provided with an encapsulating layer (not shown) that protects the metal from damage, corrosion and tarnishing.
  • the encapsulating layer may comprise a colourant layer such as for example but not limited to a paint layer.
  • a first comparative example was prepared, comprising a sheet of glazing material of soda-lime silica glass (Pilkington Optifloat).
  • a photocatalytic layer of titanium oxide with predominantly anatase crystal structure was applied to a first surface of the glass, and an alkali metal ion blocking under-layer of silicon oxide (thickness 30 nm) was applied between the surface of the glass and the photocatalytic layer.
  • a second comparative example was prepared, comprising a sheet of glazing material of low-iron glass (Pilkington Optiwhite).
  • a photocatalytic layer of titanium oxide with predominantly anatase crystal structure was applied to a first surface of the glass, and an alkali metal ion blocking under-layer of silicon oxide (thickness 30 nm) was applied between the surface of the glass and the photocatalytic layer.
  • a first example of the invention prepared according to the first embodiment of an antimicrobial substrate described in relation to Figure 1 , comprises: a sheet of glazing material of soda-lime silica glass, a photocatalytic layer of titanium oxide with predominantly anatase crystal structure (thickness 17 nm) applied to a first surface of the glass; an alkali metal ion blocking under-layer of silicon oxide (thickness 30 nm) applied between the surface of the glass and the photocatalytic layer and applied directly to the first surface of the glass.
  • the visible light reflecting coating is a silver metal mirror coating produced by curtain coating and is applied directly to the second surface of the glass.
  • An encapsulating layer is applied to the silver metal mirror coating.
  • photocatalytic layers may have a potent antimicrobial and specifically an antiviral effect as follows.
  • samples consisting of the first comparative example detailed above were prepared (without the silver metal mirror coating or the encapsulation layer). These samples were exposed to UVA 340 nm radiation produced by a Q Panel 340 Lamp in a dark room at a distance of 45 nm for 20 hours. The samples were then inoculated with Staphylococcus aureus strain F and the “colony reduction” of the samples investigated. Half of the samples were irradiated with light from the same lamp for 0, 5, 10, 20, 40, 60 and 90 minutes, and the other half kept in darkness for the same length of time. At the end of the time the samples were washed into a nutrient, the dilutions cultured overnight at 37 °C using 0.1 mml of 10 -2 bacterial dilutions on agar plates, and the colony counts measured.
  • Figure 2 depicts the percentage “colony reduction rate” for the comparative example samples, - Coated -, compared to the percentage “colony reduction rate ” for the comparative uncoated samples, - Uncoated - .
  • the “colony reduction rate” % is calculated by Formula (1):
  • irradiation of a photocatalytic coating in particular a titanium oxide photocatalytic coating, is particularly beneficial for the disinfection of substrates.
  • Table 1 shows the layer structures of examples and comparative examples with layer thicknesses provided in nm. In each case, the glass thickness was 6 mm. Where the term “S-L S Glass” is used, this represents soda-lime silica glass, available from Pilkington Group Limited under the trademark OptifloatTM, and where the term “Low-iron glass” is used this is low-iron glass available from Pilkington Group Limited under the trademark OptiwhiteTM.
  • Table 1 shows the associated optical data of the examples and comparative examples.
  • example 1 and example 2 a silver layer of 100 nm was provided.
  • the silver layer may be of increased thickness when applied by curtain coating.
  • Tvis is the calculated visible transmission of the sample
  • R ViS is the calculated visible reflection of the sample, both when measured with light incident upon the photocatalytic layer using a CIE C illuminant.
  • the comparative examples have high visible light transmission and comparatively low reflection, while examples 1 and 2 have zero light transmission and extremely high visible light reflection, due to the thick silver layer.
  • the a*, b* parameter is the calculated a* and b* values of the reflected light from the sample using the lab colour space and a CIE C illuminant.
  • Comparative examples 1 and 2 have a relatively neutral reflection colour, with a * and b * values each within the range from -20 to +20.
  • Example 1 exhibits excellent colour neutrality, with a * and b * values each within the range from -3 to +3, and example 2 exhibits exceptional colour neutrality, with a * and b * values each within the range from -1 to +1.
  • embodiments including a silver layer on the opposite side of the glazing sheet to the photocatalytic layer and incorporating low-iron glass are exceptionally useful for high quality antimicrobial, specifically high quality antiviral and/or antimicrobial visible light reflective mirrors due to extremely high visible light reflection and exceptional colour neutrality as well as excellent antimicrobial performance, especially excellent antiviral and antibacterial performance.
  • R ViS is greater than 90%, more preferably greater than 95%.
  • the a * and/or b * values are in the range -10 to +10. In some applications it is desirable for the a* and b* values to both be in the range -3 to +3.

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Abstract

The present invention relates to an antimicrobial and/or antiviral mirror, a method for producing an antimicrobial and/or antiviral mirror, and a use of an antimicrobial and/or antiviral mirror, wherein the antimicrobial and/or antiviral mirror comprises: a sheet of glazing material, wherein the sheet of glazing material comprises a first surface and a second surface; and a photocatalytic layer, wherein the photocatalytic layer is applied directly or indirectly to the first surface of the sheet of glazing material; and wherein the antimicrobial and/or antiviral mirror further comprises a visible light reflective layer applied directly or indirectly to the second surface.

Description

ANTIMICROBIAL AND/OR ANTIVIRAL MIRROR
The present invention relates to an antimicrobial and/or antiviral mirror, a method for producing an antimicrobial and/or antiviral mirror, an article comprising an antimicrobial and/or antiviral mirror, and to the use of an antimicrobial and/or antiviral mirror. In relation to the present invention, microbes include bacteria, viruses and fungi. The present invention is particularly related to mirrors which may be antibacterial, antiviral and antifungal in nature, especially mirrors which are antiviral and/or antibacterial.
More specifically, the present invention relates to an antimicrobial and/or antiviral mirror comprising a sheet of glazing material and a photocatalytic layer, a method of producing same, and to the use of same to reduce the presence of microbes, on a surface.
There is a need to prevent the transmission of potentially harmful microbes between humans and animals. In relation to the present invention, microbes include bacteria, viruses and fungi. One way in which microbes are transmitted is by “surface transmission”. This is where an individual interacts with a surface that has previously been seeded with microbes, for example by previous interaction with the surface by infectious individuals.
Transparent and semi-transparent surfaces, such as mirrors, are commonly found in environments which are shared by multiple individuals. As such, transparent and semi transparent surfaces may act as a vector for the transmission of microbes especially bacteria and viruses. This is particularly a problem in spaces which may be occupied by large numbers of people in succession, such as toilets, corridors, hospital rooms, shops and workplaces.
In addition, as the threat of resistance to antibiotics by certain bacterial strains increases, and as epidemics arise from the transmission of some viruses, there is an ever-increasing need for surfaces, no matter the device or application, to be able to halt the spread of micro-organisms.
Surface transmission can be significantly curtailed if, following seeding of the surface, the number of infectious microbes is reduced, preferably to a level where there is no risk of transmission to subsequent individuals. However, there exists a need for a surface which even though located in areas of persistent human contact, may be readily cleaned to provide a safer environment.
In order to rapidly reduce the number of microbes applied to a surface, it is usual to clean a surface with a detergent. However, such cleaning is often performed manually and is time consuming. In addition, common cleaning agents may erode surfaces, especially coated glass surfaces and mirrored surfaces leading to impaired appearance and performance.
Unfortunately, for some applications, a surface may not be sufficiently inhospitable to microbes, and traditional cleaning practices and products may not successfully remove sufficient levels of microbes. In such cases, it is common to use a “disinfection” process whereby the number of infectious microbes on a smooth surface is further reduced to a safe level by denaturing, rendering many of the microbes inactive.
One method of disinfection is by cleaning surfaces using a germicidal cleaner, such as a bleach. However, the use of bleach as a disinfectant may give rise to similar problems as stated above in respect of cleaning with a detergent, namely impaired appearance and performance of the substrate surface. However, cleaning performed manually with a germicidal product can often be more damaging and corrosive to the surface. Furthermore, germicidal cleaners may not sufficiently denature all microbes on the surface.
An alternative method of disinfecting surfaces is by UV disinfection. In this situation, UV light irradiation is used to denature microbes on a surface. UV is the term given to light in the wavelength range 100 to 400nm. UV light is commonly divided into UVA (320 to 400 nm), UVB (280 to 320 nm), and UVC (100 to 280 nm). UV light is particularly effective for disinfecting surfaces, as the light penetrates microbes and alters their DNA structure, impairing and preventing replication.
In some cases, UV disinfection may be used in addition to disinfection with a germicidal cleaner. The additional UV disinfection step further reduces the prevalence of microbes on the surface, therefore reducing the likelihood of infection due to contact with the surface. An advantage of using UV disinfection in addition to disinfection with a germicidal cleaner is that this may allow the use of less corrosive cleaners, or may allow increased confidence that the surface is fully disinfected.
It is the object of the present invention to provide an antimicrobial and antiviral mirror, more specifically antibacterial and/or antiviral and/or antifungal mirrors, especially antiviral and antibacterial mirrors which may be effectively disinfected in an efficient manner. In addition, it is an object of the present invention to provide antibacterial and/or antiviral and/or antifungal mirrors, especially antiviral and antibacterial mirrors which also meet the optical and durability requirements of mirrors.
According to a first aspect of the invention there is provided an antimicrobial and/or antiviral mirror comprising: a sheet of glazing material, wherein the sheet of glazing material comprises a first surface and a second surface; and a photocatalytic layer, wherein the photocatalytic layer is applied directly or indirectly to the first surface of the sheet of glazing material; and wherein the antimicrobial and/or antiviral mirror further comprises a visible light reflective layer applied directly or indirectly to the second surface.
In relation to the present invention the inventors have surprisingly found that photocatalytic layers which provide for example self-cleaning properties, may also provide an antimicrobial effect. In particular, the photocatalytic layers may provide an antibacterial and/or antiviral effect.
Preferably, the photocatalytic layer may comprise titanium oxide, preferably titanium oxide with a predominantly anatase crystal structure. More preferably, the photocatalytic layer comprises titanium oxide with greater than or equal to 50% anatase. It has been found that a photocatalytic layer comprising titanium oxide has excellent antimicrobial properties, especially when illuminated with UV light. Furthermore, it has been found that, following irradiation of the photocatalytic layer with UV light, an increased antimicrobial effect persists even in the absence of any light at all.
Preferably the photocatalytic layer has a photocatalytic activity of greater than 5 x 10-3 cm 1 min 1. More preferably the photocatalytic layer has a photocatalytic activity of greater than 1 x 102 cnr1 min 1. Even more preferably the photocatalytic layer has a photocatalytic activity of greater than 3 x 10-2 cm-1 min-1.
Photocatalytic activity for the purposes of this specification is determined by measuring the rate of decrease of the integrated absorbance of the infra-red absorption peaks corresponding to the C-H stretches of a thin film of stearic acid, formed on the coated substrate, under illumination by UV light from a UVA lamp having an intensity of about 32 W/m2at the surface of the coated substrate and a peak wavelength of 351 nm.
The stearic acid film may be formed on samples of the glasses, 7 to 8 cm square, by spin casting 20 pi of a solution of stearic acid in methanol (8.8 x 103mol dm-3) on the coated surface of the glass at 2000 rpm for 1 minute. Infra red spectra may be measured in transmission, and the peak height of the peak corresponding to the C-H stretches (at about 2700 to 3000 cm 1) of the stearic acid film measured and the corresponding peak area determined from a calibration curve of peak area against peak height. A suitable UVA lamp is a UVA-351 lamp (obtained from the Q-Panel Co., Cleveland, Ohio, USA) having a peak wavelength of 351 nm and an intensity at the surface of the coated glass of approximately 32 W/m2 The photocatalytic activity is expressed in this specification as the rate of decrease of the area of the IR peaks (in units of cnr1 min-1).
Preferably, the photocatalytic layer meets the EN 1096-5-2016 standard test method and classification for the self-cleaning performances of coated glass surfaces.
Preferably, the photocatalytic layer has a thickness of 50 nm or lower. More preferably, the photocatalytic layer has a thickness of 40 nm or lower.
Preferably, the photocatalytic layer has a thickness of from 10 nm to 40 nm. More preferably, the photocatalytic layer has a thickness from 15 to 30 nm. Even more preferably, the photocatalytic layer has a thickness from 15 to 20 nm.
Particular microbes and viruses which may be denatured by the antimicrobial and/or antiviral mirror according to the present invention include for example but are not limited to: gram positive and gram negative bacteria, including for example Staphylococcus aureus and methicillin-resistant Staphylococcus aureus (MRSA), and corona viruses including SARS-CoV-2. The antimicrobial and/or antiviral mirror according to the present invention may reduce the survival of one or more microbes on one or more surfaces of the sheet glazing material, such as for example bacteria and/or viruses, compared to a non-coated sheet of the same glazing material.
Also in relation to the antimicrobial and/or antiviral mirror according the present invention, the visible light reflective layer may comprises a metal layer.
Preferably, the metal layer may comprise one or more of silver metal, chromium metal, tin metal, nickel metal, aluminium metal or a combination thereof.
In addition, in relation to the antimicrobial and/or antiviral mirror according to the present invention the sheet of glazing material preferably comprises glass.
According to the present invention, the sheet of glazing material may be a planar body that transmits at least 10% of incident visible light, or may be reversibly modified to transmit at least 10% of incident visible light.
Also in relation to the present invention the antimicrobial and/or antiviral mirror comprises a visible light reflective layer applied directly or indirectly upon the second surface which preferably comprises a metal layer and/or a metalloid layer.
Preferably, the metal layer comprises one or more of silver metal, chromium metal, tin metal, nickel metal, aluminium metal or a combination thereof.
It is preferred in relation to the present invention that the visible light reflective layer comprises a metal layer. The metal layer is preferably applied to the second surface of the sheet of glazing material. The metal layer preferably forms a mirror layer.
In addition, the antimicrobial and/or antiviral mirror according to the present invention preferably comprises an encapsulation layer applied to the visible light reflective layer.
The encapsulating layer may be applied indirectly to the second surface of the sheet of glazing material, such that the metal mirror coating is between the encapsulating layer and the sheet of glazing material. The encapsulating layer preferably protects the metal mirror coating from damage, tarnishing and corrosion.
For some applications, it is desirable to provide a metal mirror coating with minimal visible light transmission. In such applications, preferably the metal mirror coating has a thickness of from 100 nm to 1 cm. Thicker coatings are less cost effective, while thinner coatings may not be sufficiently opaque (non-transmissive). The thickness of the metal mirror coating should be sufficient to enable visible light to be mostly reflected rather than transmitted.
Alternatively, it may be desirable to provide a so called “half mirror” in which a balance may be found between the reflection and transmission of visible light. In such applications, the metal mirror coating preferably has a thickness of from 20 nm to 100 nm.
Preferably in relation to the antimicrobial and/or antiviral mirror according to the present invention, the sheet of glazing material comprises glass. Preferably, the sheet of glazing material comprises flat glass. Preferably the sheet of glazing material comprises float glass. Preferably the sheet of glazing material comprises soda-lime silica float glass. Soda-lime silica float glass is particularly beneficial as it is widely available and cost effective. In addition, it may be coated using highly efficient online coating processes.
It is particularly preferred that the glass is low-iron glass. According to the present invention, low-iron glass comprises less than 200 ppm by weight iron.
Alternatively, the sheet of glazing material comprises down-drawn or rolled glass. Alternatively, the sheet of glazing material may comprise resin, such as polycarbonate.
Further, when the antimicrobial and/or antiviral mirror according to the present invention comprises a glass substrate, the glass substrate may preferably comprise alternative forms of glass such as for example but not limited to: borosilicate glass, rolled plate glass, ceramic glass, toughened glass, chemically strengthened glass, hallow glass or glass shaped for articles such as bottles, jars and medical containers.
Preferably, the first surface comprises an alkali metal ion blocking under-layer between the surface of the substrate and the photocatalytic layer. Preferably, in relation to the antimicrobial and/or antiviral mirror according to the present invention, the first surface further comprises an alkali metal ion blocking layer, wherein the alkali metal blocking layer is located between the first surface of the sheet of glazing material and the photocatalytic layer.
Preferably, the alkali metal ion blocking layer comprises silicon oxide. Preferably, the alkali metal ion blocking layer comprising silicon oxide has a thickness of from 15 to 40 nm, more preferably a thickness of between 25 and 35 nm.
Further in relation to the present invention, the antimicrobial and/or antiviral mirror preferably further comprises an encapsulation layer applied to the visible light reflective layer. The encapsulation layer preferably prevents damage or tarnishing of the visible light reflective layer. Preferably the encapsulation layer comprises a paint layer.
Also in relation to the present invention the photocatalytic layer may comprise copper and/or silver. Preferably, the photocatalytic layer comprises copper and/or silver containing particles. Preferably the particles are nanoparticles and/or microparticles.
According to the present invention, a nanoparticle may be particle with a diameter less than 100 nm. According to the present invention, a microparticle may be a particle with a diameter less than 1000 nm.
In addition, the antimicrobial and/or antiviral mirror according to the present invention, may further comprise an antimicrobial layer. The antimicrobial layer is preferably applied to the sheet of glazing material such that the photocatalytic layer is located between the sheet of glazing material and the antimicrobial layer.
Preferably the antimicrobial layer is applied to the substrate such that the photocatalytic layer is between the antimicrobial layer and the substrate.
Preferably, the antimicrobial layer comprises copper and/or silver. Preferably, the antimicrobial layer is in direct contact with the photocatalytic layer. Preferably, the antimicrobial layer is in the form of islands, such that at least a portion of the photocatalytic layer is exposed between the islands of the antimicrobial layer. Preferably the ratio of the sum of the areas of the island portions to the sum of the area of exposed photocatalytic layer is from 0.01 to 0.20.
Preferably, the diameter calculated by converting the average area of the island portion into a circle when observed along the cross-section of the antimicrobial layer is 1 to 20 nm.
Alternatively, the antimicrobial layer may comprise a matrix comprising particles of copper and/or silver. The particles of copper and/or silver may be nanoparticles and/or microparticles.
Copper and silver metals are preferred as same act upon microbes, especially bacteria, by oligodynamic action which may cause complete inhibition of the microbe.
Preferably the antimicrobial and/or antiviral mirror according to the present invention demonstrates a log reduction of at least 3 against one of Staphylococcus aureus, SARS- CoV-2, E.coli, P. gingivitis, or S.mutans. More preferably, the antimicrobial and/or antiviral mirror according to the present invention demonstrates a log reduction of at least 4 against one of Staphylococcus aureus, SARS-CoV-2, E.coli , P. gingivitis, or S.mutans, more preferably greater than 5, and most preferably 6.
According to a second aspect of the invention there is provided a method for producing an antimicrobial and/or antiviral mirror according to the first aspect of the present invention comprising the steps of: i) providing a sheet of glazing material with a first surface and a second surface; ii) applying a photocatalytic layer directly or indirectly to the first surface; and iii) applying a visible light reflective layer to the second surface.
Preferably the photocatalytic layer is applied by chemical vapour deposition. More preferably the photocatalytic layer is applied by chemical vapour deposition during the float glass production process, and is therefore an “online coating”. As used herein, “online coating” relates to the use of chemical vapour deposition coating beams during the float glass production process. Where the photocatalytic layer is applied by chemical vapour deposition it may be possible to produce the antimicrobial substrate in large volumes. In addition, where the photocatalytic layer is applied by chemical vapour deposition and the photocatalytic layer comprises titanium oxide, a higher proportion of titanium oxide with a predominantly anatase crystal structure may result.
Preferably, the photocatalytic layer is applied by chemical vapour deposition using a precursor gaseous mixture comprising TiCU. Photocatalytic layers applied by chemical vapour deposition using precursor gaseous mixtures comprising TiCU provide a higher proportion of anatase crystal structure titanium oxide than alternative precursor mixtures.
Alternatively, the photocatalytic layer may be applied by physical vapour deposition. Physical vapour deposition is also known as sputtering.
Alternatively, the photocatalytic layer may be formed by curing a liquid coating precursor. Examples of liquid coating precursors include tetraorthoxysilicate (TEOS) and perhydropolysilazane (PHPS). Where a liquid coating precursor is used photocatalytic particles may be included in the precursor mixture.
Forming the photocatalytic layer from a liquid coating precursor may allow different properties to be imparted to the layer.
In relation to the second aspect of the present invention the visible light reflective layer preferably comprises a metal layer applied to the sheet of glazing material by chemical vapour deposition, physical vapour deposition, or wet deposition.
Preferably, the visible light reflective layer is applied to the sheet of glazing material by a wet deposition technique selected from: curtain coating, spray coating, spin coating, roller coating, slot-die coating, or rod draw coating.
Preferably, the visible light reflecting layer comprises a silver containing mirror layer or a chromium containing mirror layer.
Preferably the visible light reflective layer is a silver mirror layer. Preferably the silver mirror layer is formed by curtain coating. Alternatively, the silver mirror layer may be formed by alternative coating methods, including draw coating, spray coating and roll coating.
Alternatively, the visible light reflecting layer is a chromium containing mirror layer deposited by physical vapour deposition.
Preferably in relation to the method according to the second aspect of the present invention the visible light reflecting layer comprises: a silver containing mirror layer deposited by curtain coating; or a chromium containing mirror layer deposited by physical vapour deposition.
According to a third aspect of the invention, there is provided an antimicrobial and/or antiviral article comprising an antimicrobial and/or antiviral mirror according to the first aspect of the invention or produced by the method according to the second aspect of the invention.
According to a fourth aspect of the invention there is provided a use of an antimicrobial and antiviral mirror according to the first aspect of the invention or produced according to the second aspect of the invention, in a glazing frame, wall, bulkhead, blind, and/or door, wherein the antimicrobial and/or antiviral mirror is installed to allow the photocatalytic layer to face towards an external environment.
Preferably the use of an antimicrobial and antiviral mirror according to the fourth aspect of the present invention further comprises the steps of irradiating the antimicrobial substrate with UV light from a UV light source for between 1 and 20 minutes.
In relation to the present invention, UV light is electromagnetic radiation with a wavelength from 30 nm to 400 nm.
Preferably, the UV light has a peak wavelength above 200 nm, more preferably above 220 nm, even more preferably above 250 nm.
In relation to the present invention, the peak wavelength of light is the wavelength with the highest intensity in the light spectrum. For example, the peak wavelength of UV light is the wavelength with the highest intensity in the UV spectrum of 10 to 400 nm. Preferably, the UV light is activated using an automated sensor process or a timer.
According to the present invention, an automated sensor process may include a sensor device for sensing parameter information, a communication system for relaying the parameter information to a computational device which determines a response.
Preferably, the UV light source is a mobile UV light source.
Preferably the mobile UV light source may be actuated between a position where light from the UV light source may impinge upon the antimicrobial substrate, and a position in which light from the UV light source does not impinge upon the antimicrobial substrate.
Preferably, the mobile UV light source is attached to a robotic device. Preferably the robotic device is: an actuating arm; a wheeled, legged or tracked mobile carrier; or a retracting arm.
Preferably, the use of an antimicrobial and/or antiviral mirror according to the present invention further comprises a cleaning step, preferably wherein the antimicrobial and/or antiviral mirror is cleaned with a cleaning product, preferably a detergent and/or a germicidal cleaning product.
Preferably the cleaning step is an automated cleaning step, wherein the antimicrobial substrate is cleaned using sprayers, air knives and/or wipers. Alternatively, the cleaning step may be a manual cleaning step.
It will be appreciated that preferable features disclosed herein according to the first, aspect of the present invention may also be applied to the second, third and fourth aspects of the present invention respectively.
Embodiments of the present invention will now be described by way of example only with reference to the following examples and drawings in which:
Figure 1 illustrates a cross sectional view through an antimicrobial substrate according to a first embodiment of the present invention. Figure 2 illustrates the Colony Reduction % of a coated comparative example compared to an uncoated comparative example.
Embodiments of the invention will now be described in which like features are indicated by like numerals.
In a first embodiment of the present invention there is provided an antimicrobial substrate 10 as depicted in Figure 1 , comprising a sheet of glazing material 1 and a photocatalytic layer 2, wherein the sheet of glazing material 1 comprises a first surface 1a and a second surface 1b, and wherein the photocatalytic layer 2 is applied to the first surface 1a. The photocatalytic layer 2 may be directly applied to the first surface 1a. Alternatively, the photocatalytic layer 2 may be indirectly applied to the first surface 1a. For example, an ion migration blocking layer may be located between the photocatalytic layer 2 and the sheet of glazing material 1. The antimicrobial substrate 10 further comprises a visible light reflective layer 3 applied to the second surface 1b. The visible light reflective layer 3 may be directly or indirectly applied to the second surface 1 b, provided that any intervening layers are at least partially visible light transmissive.
In this embodiment, it is preferred that a low-iron glass is used as the sheet of glazing material, to increase the transmission of visible light through the sheet of glazing material and thereby increase the amount of visible light reflected.
In a particularly preferred embodiment, the visible reflecting layer 3 comprises metal and the photocatalytic layer 2 comprises titanium oxide. Preferably the metal comprises silver metal, chromium metal, aluminium metal, tin metal, nickel metal or a combination thereof. It is also preferred that the visible light reflecting metal layer 3 is provided with an encapsulating layer (not shown) that protects the metal from damage, corrosion and tarnishing. The encapsulating layer may comprise a colourant layer such as for example but not limited to a paint layer.
Examples of embodiments of the invention will now be described.
A first comparative example was prepared, comprising a sheet of glazing material of soda-lime silica glass (Pilkington Optifloat). A photocatalytic layer of titanium oxide with predominantly anatase crystal structure (thickness 17 nm) was applied to a first surface of the glass, and an alkali metal ion blocking under-layer of silicon oxide (thickness 30 nm) was applied between the surface of the glass and the photocatalytic layer.
A second comparative example was prepared, comprising a sheet of glazing material of low-iron glass (Pilkington Optiwhite). A photocatalytic layer of titanium oxide with predominantly anatase crystal structure (thickness 17 nm) was applied to a first surface of the glass, and an alkali metal ion blocking under-layer of silicon oxide (thickness 30 nm) was applied between the surface of the glass and the photocatalytic layer.
A first example of the invention, prepared according to the first embodiment of an antimicrobial substrate described in relation to Figure 1 , comprises: a sheet of glazing material of soda-lime silica glass, a photocatalytic layer of titanium oxide with predominantly anatase crystal structure (thickness 17 nm) applied to a first surface of the glass; an alkali metal ion blocking under-layer of silicon oxide (thickness 30 nm) applied between the surface of the glass and the photocatalytic layer and applied directly to the first surface of the glass. In this example, the visible light reflecting coating is a silver metal mirror coating produced by curtain coating and is applied directly to the second surface of the glass. An encapsulating layer is applied to the silver metal mirror coating.
The inventors have found that photocatalytic layers may have a potent antimicrobial and specifically an antiviral effect as follows. For example, samples consisting of the first comparative example detailed above were prepared (without the silver metal mirror coating or the encapsulation layer). These samples were exposed to UVA 340 nm radiation produced by a Q Panel 340 Lamp in a dark room at a distance of 45 nm for 20 hours. The samples were then inoculated with Staphylococcus aureus strain F and the “colony reduction” of the samples investigated. Half of the samples were irradiated with light from the same lamp for 0, 5, 10, 20, 40, 60 and 90 minutes, and the other half kept in darkness for the same length of time. At the end of the time the samples were washed into a nutrient, the dilutions cultured overnight at 37 °C using 0.1 mml of 10-2 bacterial dilutions on agar plates, and the colony counts measured.
Figure 2 depicts the percentage “colony reduction rate” for the comparative example samples, - Coated -, compared to the percentage “colony reduction rate ” for the comparative uncoated samples, - Uncoated - . The “colony reduction rate” % is calculated by Formula (1):
Colony Reduction % = 100 - (colony numbers/ initial colony numben=o * 100) (1 )
Surprisingly, the results indicate that a coated sample is more effective after irradiation has ceased - sample Coated (Dark) - , compared to an uncoated sample with continuing irradiation - Uncoated (Light)
The colony reduction demonstrated by the comparative example sample irradiated with UVA for 24 hours then kept in the dark for 90 minutes after inoculation, demonstrates a log reduction of 6 in relation to the Staphylococcus aureus strain F.
As such, it is demonstrated that irradiation of a photocatalytic coating, in particular a titanium oxide photocatalytic coating, is particularly beneficial for the disinfection of substrates.
Table 1 shows the layer structures of examples and comparative examples with layer thicknesses provided in nm. In each case, the glass thickness was 6 mm. Where the term “S-L S Glass” is used, this represents soda-lime silica glass, available from Pilkington Group Limited under the trademark Optifloat™, and where the term “Low-iron glass” is used this is low-iron glass available from Pilkington Group Limited under the trademark Optiwhite™.
In addition, Table 1 shows the associated optical data of the examples and comparative examples.
In example 1 and example 2 a silver layer of 100 nm was provided. However, the silver layer may be of increased thickness when applied by curtain coating.
Tvis is the calculated visible transmission of the sample, and RViS is the calculated visible reflection of the sample, both when measured with light incident upon the photocatalytic layer using a CIE C illuminant. The comparative examples have high visible light transmission and comparatively low reflection, while examples 1 and 2 have zero light transmission and extremely high visible light reflection, due to the thick silver layer. The a*, b* parameter is the calculated a* and b* values of the reflected light from the sample using the lab colour space and a CIE C illuminant. Comparative examples 1 and 2 have a relatively neutral reflection colour, with a* and b* values each within the range from -20 to +20. Example 1 exhibits excellent colour neutrality, with a* and b* values each within the range from -3 to +3, and example 2 exhibits exceptional colour neutrality, with a* and b* values each within the range from -1 to +1. This indicates that embodiments including a silver layer on the opposite side of the glazing sheet to the photocatalytic layer and incorporating low-iron glass are exceptionally useful for high quality antimicrobial, specifically high quality antiviral and/or antimicrobial visible light reflective mirrors due to extremely high visible light reflection and exceptional colour neutrality as well as excellent antimicrobial performance, especially excellent antiviral and antibacterial performance.
Therefore, in some embodiments it preferred that RViS is greater than 90%, more preferably greater than 95%.
Preferably, the a* and/or b* values are in the range -10 to +10. In some applications it is desirable for the a* and b* values to both be in the range -3 to +3.
Table 1.
Figure imgf000017_0001

Claims

1. An antimicrobial and/or antiviral mirror comprising: a sheet of glazing material, wherein the sheet of glazing material comprises a first surface and a second surface; and a photocatalytic layer, wherein the photocatalytic layer is applied directly or indirectly to the first surface of the sheet of glazing material; and wherein the antimicrobial and/or antiviral mirror further comprises a visible light reflective layer applied directly or indirectly to the second surface.
2. An antimicrobial and/or antiviral mirror according to claim 1 , wherein the photocatalytic layer comprises titanium oxide, preferably titanium oxide with a predominantly anatase crystal structure.
3. An antimicrobial and/or antiviral mirror according claim 1 or claim 2, wherein the visible light reflective layer comprises a metal layer.
4. An antimicrobial and/or antiviral mirror according to claim 3, wherein the metal layer comprises one or more of silver metal, chromium metal, tin metal, nickel metal, aluminium metal or a combination thereof.
5. An antimicrobial and/or antiviral mirror according to any preceding claim, wherein the sheet of glazing material comprises glass.
6. An antimicrobial and/or antiviral mirror according to any preceding claim, wherein the first surface further comprises an alkali metal ion blocking layer, wherein the alkali metal blocking layer is located between the first surface of the sheet of glazing material and the photocatalytic layer.
7. An antimicrobial and/or antiviral mirror according to any preceding claim, further comprising an encapsulation layer applied to the visible light reflective layer.
8. An antimicrobial and/or antiviral mirror according to any preceding claim, wherein the photocatalytic layer comprises copper and/or silver.
9. An antimicrobial and/or antiviral mirror according to any preceding claim, wherein the antimicrobial and/or antiviral mirror further comprises an antimicrobial layer, and wherein the photocatalytic layer is located between the sheet of glazing material and the antimicrobial layer.
10. An antimicrobial and/or antiviral mirror according to any preceding claim, wherein the antimicrobial and/or antiviral mirror demonstrates a log reduction of at least 3 against one of Staphylococcus aureus, SARS-CoV-2, E.coli, P. gingivitis, or S.mutans.
11. A method for producing an antimicrobial and/or antiviral mirror according to any of claims to 10, comprising the steps of: i) providing a sheet of glazing material with a first surface and a second surface; ii) applying a photocatalytic layer directly or indirectly to the first surface; and iii) applying a visible light reflective layer to the second surface.
12. A method for producing an antimicrobial and/or antiviral mirror according to claim 11 , wherein the photocatalytic layer is applied by chemical vapour deposition.
13. A method for producing an antimicrobial and/or antiviral mirror according to claim 11 or claim 12, wherein the visible light reflective layer comprises a metal layer, and wherein the metal layer is applied by: chemical vapour deposition, physical vapour deposition, or wet deposition.
14. A method for producing an antimicrobial and/or antiviral mirror according to claim 13, wherein wet deposition is selected from: curtain coating, spray coating, spin coating, roller coating, slot-die coating, or rod draw coating.
15. A method for producing an antimicrobial and/or antiviral mirror according to any of claims 11 to 14, wherein the visible light reflecting layer comprises silver metal, chromium metal, tin metal, nickel metal, aluminium metal or a combination thereof.
16. A method for producing an antimicrobial and/or antiviral mirror according to claim 15, wherein the visible light reflecting layer comprises: a silver containing mirror layer deposited by curtain coating; or a chromium containing mirror layer deposited by physical vapour deposition.
17. An antimicrobial and/or antiviral article comprising an antimicrobial and/or antiviral mirror according to any of claims 1 to 10 or produced by the method according to any of claims 11 to 16.
18. Use of an antimicrobial and/or antiviral mirror according to any of claims 1 to 10 or produced by the method according to any of claims 11 to 16, in a glazing frame, wall, bulkhead, blind, and/or door, wherein the antimicrobial and/or antiviral mirror is installed to allow the photocatalytic layer to face towards an external environment.
19. Use of an antimicrobial and/or antiviral mirror according to claim 19, wherein the antimicrobial and/or antiviral mirror is irradiated with UV light from a UV light source for a period of 1 to 20 minutes.
20. Use of an antimicrobial and/or antiviral mirror according to claim 19, wherein the UV light has a peak wavelength above 200 nm, more preferably above 220 nm, even more preferably above 250 nm.
21. Use of an antimicrobial and/or antiviral mirror according to claim 19 or 20, wherein the UV light is activated using an automated sensor process or a timer.
22. Use of an antimicrobial and/or antiviral mirror according to any of claims 19 to 21 , wherein the UV light source is a mobile UV light source.
23. Use of an antimicrobial and/or antiviral mirror according to any of claims 18 to 22, wherein the antimicrobial and/or antiviral mirror is cleaned with a cleaning product, preferably a detergent and/or a germicidal cleaning product.
PCT/GB2021/051588 2020-06-23 2021-06-22 Antimicrobial and/or antiviral mirror WO2021260371A1 (en)

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GBGB2011237.1A GB202011237D0 (en) 2020-07-21 2020-07-21 Antimicrobial and/or antiviral mirror
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EP0978494A1 (en) * 1998-08-06 2000-02-09 Murakami Corporation Anti-fog mirror and method for manufacturing the same
JP2004188297A (en) * 2002-12-10 2004-07-08 Ichikoh Ind Ltd Photocatalyst activity structure
WO2006064060A1 (en) * 2004-12-16 2006-06-22 Glaverbel Substrate with antimicrobial properties
EP1828072A2 (en) * 2004-11-15 2007-09-05 Cardinal CG Company Methods and equipment for depositing coatings having sequenced structures
EP1916547A1 (en) * 2006-10-23 2008-04-30 Ichikoh Industries, Ltd. Mirror and hydrophilic composite film having photo catalyst activity
US20170182479A1 (en) * 2014-05-30 2017-06-29 Murakami Corporation Hydrophilic member, method for manufacturing same and hydrophilic member maintenance method

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0820967A1 (en) * 1996-07-26 1998-01-28 Murakami Corporation Anti-fog element
EP0978494A1 (en) * 1998-08-06 2000-02-09 Murakami Corporation Anti-fog mirror and method for manufacturing the same
JP2004188297A (en) * 2002-12-10 2004-07-08 Ichikoh Ind Ltd Photocatalyst activity structure
EP1828072A2 (en) * 2004-11-15 2007-09-05 Cardinal CG Company Methods and equipment for depositing coatings having sequenced structures
WO2006064060A1 (en) * 2004-12-16 2006-06-22 Glaverbel Substrate with antimicrobial properties
EP1916547A1 (en) * 2006-10-23 2008-04-30 Ichikoh Industries, Ltd. Mirror and hydrophilic composite film having photo catalyst activity
US20170182479A1 (en) * 2014-05-30 2017-06-29 Murakami Corporation Hydrophilic member, method for manufacturing same and hydrophilic member maintenance method

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