BOULANGER, Pierre (Centre R&DRue de l'Auror, 2 Jumet, B-6040, BE)
MARIAGE, Fabian (Centre R&DRue de l'Auror, 2 Jumet, B-6040, BE)
BOULANGER, Pierre (Centre R&DRue de l'Auror, 2 Jumet, B-6040, BE)
| CLAIMS 1. Method for obtaining a glass article, said method including: (i) the partial and/or complete inclusion of nanoparticles in the mass of a glass substrate close to at least one surface of the glass substrate, the nanoparticles being formed of at least one inorganic compound; (ii) the deposition of at least one antimicrobial agent onto said surface of the glass substrate; and (iii) the diffusion of the antimicrobial agent beneath said surface of the glass substrate; where the partial and/or complete inclusion of nanoparticles is carried out by flame-assisted spraying, so as to provide the energy required for diffusing/incorporating the nanoparticles at the moment when the nanoparticles are deposited. 2. Method according to the preceding claim, c h a r a c t e r i z e d in that the partial and/or complete inclusion of nanoparticles includes the deposition of at least one salt of the inorganic compound onto at least one surface of the glass substrate . 3. Method according to the preceding claim, c h a r a c t e r i z e d in that the deposition of at least one salt of the inorganic compound and the deposition of the antimicrobial agent are carried out at least partially simultaneously using a solution of at least one salt of the inorganic compound and at least one salt of the antimicrobial agent. 4. Method according to any of the preceding claims, c h a r a c t e r i z e d in that the partial and/or complete inclusion of the nanoparticles includes heating the glass substrate so as to provide the energy required for diffusing/incorporating the nanoparticles into the mass of the glass substrate. 5. Method according to any of the preceding claims, c h a r a c t e r i z e d in that the deposition of the antimicrobial agent includes the deposition of an element which is selected from the elements silver (Ag) , copper (Cu) , tin (Sn) and zinc (Zn) . 6. Method according to the preceding claim, c h a r a c t e r i z e d in that the deposition of the antimicrobial agent includes the deposition of the element silver (Ag) . 7. Method according to any of the preceding claims, c h a r a c t e r i z e d in that the partial and/or complete inclusion of the nanoparticles is carried out such that the nanoparticles become at least partially crystallized. 8. Method according to any of the preceding claims, c h a r a c t e r i z e d in that the partial and/or complete inclusion of the nanoparticles is carried out such that the nanoparticles become totally crystallized. 9. Method according to any of the preceding claims, c h a r a c t e r i z e d in that the inorganic compound is selected from oxides, nitrides, carbides and the combinations of at least two oxides and/or nitrides and/or carbides. 10. Method according to the preceding claim, c h a r a c t e r i z e d in that the inorganic compound is selected from the compounds of magnesium, calcium, strontium, barium, scandium, yttrium, lanthanum, titanium, zirconium, vanadium, niobium, tantalum, aluminum, gallium, indium, silicon, germanium, and the combinations of at least two of the aforesaid compounds . 11. Method according to the preceding claim, c h a r a c t e r i z e d in that the inorganic compound is an aluminum compound. 12. Method according to the preceding claim, c h a r a c t e r i z e d in that the inorganic compound is an aluminum oxide. 13. Method according to any of the preceding claims, c h a r a c t e r i z e d in that the glass substrate is formed of a sheet of flat glass. 14. Method according to the preceding claim, c h a r a c t e r i z e d in that the glass substrate is formed of a sodocalcic-type sheet of flat glass. |
Field of the invention
The present invention relates to a glass article at least one of the surfaces of which possesses antimicrobial properties which withstand a temperature treatment, in particular a temperature treatment with a view to the subsequent tempering of same. The present invention further relates to a method for obtaining a glass article.
Solutions of the prior art
Various types of glass substrates exist having a surface with antimicrobial properties, and they all possess at least one so-called "antimicrobial" agent. The latter is often situated at the surface of said article. Examples of a known antimicrobial agent are silver (Ag) , copper (Cu) or zinc (Zn) .
A known glass substrate having an antimicrobial property, in particular that of patent application WO2005/042437 Al, is obtained by diffusing the antimicrobial agent, in particular silver (Ag) , from one of the surfaces of the substrate towards the mass of the substrate, to a depth of the order of 2 micrometers .
Another known type of glass substrate having an antimicrobial property comprises a coating on one of the surfaces thereof, which is formed of a binder and an antimicrobial agent dispersed in said binder. Such examples of substrates are given in patent applications WO03/056924 Al and WO2006/064060 Al .
Unfortunately, irrespective of the type of substrate anticipated, the antimicrobial properties are only slightly resistant to a treatment at temperatures higher than 400 °C. Indeed, due to the rapid diffusion of the Ag element at these temperatures, the latter gradually migrates from the surface or from an area close to the surface, where it is effective in neutralizing the microbes, towards the mass of the glass substrate where it is no longer available to serve the antimicrobial function thereof. Such temperatures, which are typically those required for tempering glass (-650-700 °C) , then result in a drastic decrease in the antimicrobial properties of the glass that was heat-treated.
That being said, increasingly more glass applications require sheets of tempered glass for safety reasons, given that such glass has enhanced impact resistance.
One solution to the problem occurring as a result of heat-treating a glass substrate having antimicrobial properties is already known. This involves the use of a so-called "diffusion barrier" layer so as to decrease or slow down the diffusion of the silver into the mass of the glass and thus maximally preserve the initial antimicrobial activity. The prior art describes the use of such a layer, which is then deposited directly onto the surface of the glass, imperatively between the glass and the antimicrobial agent. The substrate must then include a second layer deposited on the barrier layer and comprising the antimicrobial agent, alone or in combination with a binder. Such a solution to the problem is described, in particular, in international patent application WO2006/064060 Al .
This technical solution, however, has certain limitations. As a matter of fact, the introduction of one or more layers onto a glass substrate often results in a deterioration of the optical and/or esthetic properties of the substrate, e.g., such as decreased light transmission, a change in coloring or increased light reflection.
In addition, this technical solution requires the successive deposition of at least two layers onto the glass substrate, thereby necessarily resulting in additional steps in the manufacturing process, a higher cost, etc.
Another technical solution to the problem of the silver diffusing from the surface towards the mass would be to use a higher concentration of silver from the beginning so that the negative effect of said diffusion on the antimicrobial activity remains insignificant or weak. However, this solution is from the very start unconvincing for obvious economic reasons but likewise for esthetic reasons, because, as is known, an excessively high concentration of silver results in an unsightly yellow coloring of the glass. Aims of the invention
The aim of the invention, in particular, is to overcome the latter disadvantages by solving the technical problem, namely the decrease or slow-down in the diffusion of the silver into the glass as a result of heat-treating a glass substrate having antimicrobial properties.
Specifically, one aim of the invention, in at least one of the embodiments thereof, is to provide a glass substrate having antimicrobial properties, the antimicrobial properties of which remain stable at temperatures higher than 400°C. In particular, one aim of the invention is to provide a glass substrate having antimicrobial properties, the antimicrobial properties of which remain stable during a temperature treatment with a view to the subsequent tempering thereof .
Another aim of the invention is to provide a glass substrate having antimicrobial properties which does not comprise any layer and/or require any step of depositing layers. Finally, a final aim of the invention is to provide a solution to the disadvantages of the prior art, which is simple, fast and economical. Disclosure of the invention
According to a particular embodiment, the invention relates to a glass article including:
(i) at least one antimicrobial agent diffused beneath at least one glass surface; and
(ii) nanoparticles which are at least partially incorporated into the mass of the glass close to said surface and are formed of at least one inorganic compound .
The invention also relates to a method for obtaining a glass article, said method including:
(i) the partial and/or complete inclusion of nanoparticles in the mass of a glass substrate close to at least one surface of the glass substrate, the nanoparticles being formed of at least one inorganic compound;
(ii) the deposition of at least one antimicrobial agent onto said surface of the glass substrate;
and
(iii) the diffusion of the antimicrobial agent beneath said surface of the glass substrate.
The invention also relates to a method for obtaining a glass article, said method including:
(i) the partial and/or complete inclusion of nanoparticles in the mass of a glass substrate close to at least one surface of the glass substrate, the nanoparticles being formed of at least one inorganic compound;
(ii) the deposition of at least one antimicrobial agent onto said surface of the glass substrate;
and
(iii) the diffusion of the antimicrobial agent beneath said surface of the glass substrate; where the partial and/or complete inclusion of nanoparticles is carried out by flame-assisted spraying, so as to provide the energy required for diffusing/incorporating the nanoparticles at the moment when the nanoparticles are deposited.
The invention is thus based on an entirely novel and inventive approach because it enables the disadvantages of the glass products of the prior art to be resolved and the stated technical problem to be solved. The inventors have indeed demonstrated that it was possible to obtain a glass substrate having temperature-resistant antimicrobial properties, without making use of layers, by combining an antimicrobial agent diffused, in a known manner, beneath the surface of the glass with nanoparticles which are formed of at least one inorganic compound and which are completely and/or partially incorporated into the mass of said glass close to the surface thereof. Surprisingly, the inventors then demonstrated that the presence of nanoparticles included in the surface or beneath the surface of the glass article enabled the temperature-related diffusion of the silver to be stopped or slowed down. List of the figures
Other features and advantages of the invention will become more apparent upon reading the following description of a preferred embodiment, which is given for merely illustrative and non-limiting purposes, and from the appended drawings, in which:
figure 1, for comparative purposes, shows a silver concentration profile within the depth of the glass of glass articles having antimicrobial properties according to the prior art;
figure 2 shows, for comparative purposes, a silver concentration profile within the depth of the glass of an article, in the absence of nanoparticles; figure 3 shows a silver concentration profile within the depth of the glass of an article according to the invention, which is obtained by flame-assisted spraying;
figure 4 shows an electron transmission microscopy slide of a section of a glass article according to the invention;
figure 5 shows a silver concentration profile within the depth of the glass of an article according to the invention, obtained by flame-assisted spraying; figure 6 shows the ratio of intensities I (CsAg) /I (CsSi) (logarithmic scale) in relation to the depth (d) in the sheet of glass from the treated surface .
Description of an embodiment of the invention
The glass article according to the invention is formed of an inorganic type of glass which may belong to many categories. The inorganic glass can thus be a of a sodiocalcic type, boricate glass, lead glass, a glass including one or more additives distributed uniformly in the mass thereof, e.g., such as at least one inorganic colorant, an oxidizing compound, a viscosity-regulating agent and/or a fusion- facilitating agent. The glass article according to the invention is preferably formed of a sodiocalcic-type glass which may be clear or mass-colored. The expression "sodiocalcic glass" is used herein in the broad sense thereof and relates to any glass which contains the following basic components (expressed in total weight percentages of glass) :
Si0 2 60 to 75%
Na 2 0 10 to 20%
CaO 0 to 16%
K 2 0 0 to 10%
MgO 0 to 10%
A1 2 0 3 0 to 5% BaO 0 to 2%
BaO + CaO + MgO 10 to 20%
K 2 0 + Na 2 0 10 to 20%.
It also designates any glass including the preceding basic components, which may further include one or more additives.
According to an embodiment of the article according to the invention, the glass of the article according to the invention is formed of a sheet of flat glass. According to this embodiment, the flat glass, for example, can be float glass, drawn glass or printed glass.
Still according to this embodiment, the sheet of flat glass can be treated according to the invention on a single surface or, alternatively, on both surfaces thereof. In the case of treating a single surface of a sheet of printed glass, the treatment according to the invention is advantageously carried out on the non-printed surface of the sheet, if the latter is printed on a single surface.
The glass of the article according to the invention is preferably formed of a sheet of sodocalcic-type flat glass.
Generally speaking, it is preferred that the glass article not be coated with any layer prior to the treatment of the present invention, at the very least on the surface being treated. The glass article according to the invention can be coated with any layer after the treatment of the present invention, preferably on the surface opposite that which has been treated according to the invention.
The glass article according to the invention possesses antimicrobial properties. This is understood to designate a glass article which enables the microorganisms coming into contact therewith to be neutralized. The term "microorganisms" is understood to mean single-cell living beings of microscopic size such as bacteria, yeasts, microalgae, fungi or viruses The term "neutralize" is, at a minimum, understood to mean maintaining the starting quantity of microorganisms (static effect) ; the invention excludes an increase in this quantity. The development and proliferation of the microorganisms are thus prevented and, in almost all cases, the surface area covered by the microorganisms decreases, even in the case where the quantity thereof is maintained. According to the invention, neutralizing the microorganisms can lead to the partial and even total destruction thereof (microbicidal effect) .
In particular, the glass article according to the invention has an antibacterial (bactericidal or bacteriostatic) effect on a large number of bacteria, whether they are gram-positive or gram-negative bacteria, and in particular on at least one of the following bacteria: Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa , Enterococcus hirae. Advantageously, the glass article according to the invention likewise has an antifungal (fungicidal or fungiostatic) effect, and in particular on Candida albicans, and/or Aspergillus niger.
The glass article according to the invention includes at least one antimicrobial agent diffused beneath said surface. According to the invention, the antimicrobial agent is selected from the elements silver (Ag) , copper (Cu) , tin (Sn) and zinc (Zn) .
According to the invention, the antimicrobial agent is present either in the form of very small metal or oxide particles, or dissolved in the glass matrix .
The antimicrobial agent according to the invention is preferably the element silver (Ag) . In this case, the silver is advantageously diffused beneath the surface, whereby the ratio of intensities I (CsAg) /I (CsSi) measured on the surface according to the dynamic SIMS method is greater than 0.002, and preferably greater than or equal to 0.010. Such intensity ratio values I (CsAg) /I (CsSi) enable a sufficient antimicrobial effect to be obtained.
Measurement of the ratio of intensities
I (CsAg) /I (CsSi) was carried out on a Cameca ims-4f device. I (CsAg) is the peak intensity obtained for the CsAg+ ions, and I (CsSi) is the peak intensity obtained for the CsSi+ ions, after bombardment of the substrate surface with a beam of Cs+ ions, which gradually strip the surface of the sample. The energy of the Cs+ ion beam reaching the substrate is 5.5 keV. The angle of incidence of the beam is 42° relative to normal to the substrate. The surface values mean that the values are taken for the smallest depth possible, as soon as the value obtained is significant. Depending on the eroding velocity used, the first significant values may correspond to maximum depths of approximately 1 to 5 nm. In the present case, the surface values correspond to a maximum depth of 2 nm. In order for the values obtained to be significant, the ratio of the intensities of the isotopes I (Agl07) /I (Agl09) must, in particular, be close to the theoretical value (1.0722), in particular between 1.01 and 1.13.
According to a particular embodiment of the invention, the concentration of antimicrobial agent is distributed within the depth of the glass according to a conventional diffusion profile, i.e., a profile which decreases continuously from the surface of the glass and tends towards zero at a given depth.
According to another particular embodiment of the invention, the concentration of the antimicrobial agent is distributed into the depth of the glass according to a profile which has a minimum. The minimum is preferably situated at a distance of between 10 and 4,000 nm from the surface.
According to the invention, the nanoparticles are (i) partially incorporated into the mass of the glass; and/or
(ii) completely incorporated into the mass of the glass .
A nanoparticle which is partially incorporated into the mass of the glass is understood to mean a nanoparticle which is both in the mass of the glass and outside the mass of the glass. In other words, the nanoparticle is not completely surrounded by the glass.
A nanoparticle which is completely incorporated into the mass of the glass is understood to mean a nanoparticle which is situated beneath the surface of the glass of the article, at a close distance therefrom.
The nanoparticles of the invention are formed of at least one inorganic compound. Alternatively, when they include several inorganic compounds within them, the composition can be homogenous or heterogeneous.
According to the invention, the inorganic compound can be completely foreign to the composition of the mass of the glass of the article. Alternatively, it can already be present in the composition of the mass of the glass of the article.
Any inorganic compound which decreases or slows down the diffusion of the antimicrobial agent in response to temperature may be adequate. However, in general, in the glass article according to the invention, it is preferred that the inorganic compound comprising the nanoparticles be selected from oxides, nitrides, carbides and the combinations of at least two oxides and/or nitrides and/or carbides.
More preferably, the inorganic compound is selected from the compounds of magnesium, calcium, strontium, barium, scandium, yttrium, lanthanum, titanium, zirconium, vanadium, niobium, tantalum, aluminum, gallium, indium, silicon, germanium, and the combinations of at least two of the aforesaid compounds. The inventors advantageously demonstrated that the temperature resistance of the antimicrobial properties is particularly good when the inorganic compound is an aluminum compound and, in particular, an aluminum oxide.
According to a preferred embodiment of the invention, the nanoparticles are at least partially crystallized, i.e., a proportion of at 5% of the weight thereof consists of crystals. The crystals can belong to several different crystallization systems. Alternatively, they can also all be of the same crystallization system. At least 50% of the weight of the nanoparticles is preferably in a crystallized form. Most preferably, all of the nanoparticles are in crystallized form.
According to another embodiment of the invention, the shape of the nanoparticles is quasi-spherical. The term quasi-spherical designates a three-dimensional shape, the volume of which is similar to that of a sphere, the diameter of which would be equal to the largest dimension of an object having this quasi- spherical shape.
The nanoparticles of the invention have dimensions which are not less than 2 nm and, preferably, which are not less than 10 nm. In addition, the nanoparticles have dimensions which are not greater than 1,000 nm and, preferably, which are not greater than 500 nm, and more preferably, which are not greater than 300 nm. The term size is understood to designate the largest dimension of the nanoparticles .
The glass article according to the invention can be heat-treated and, in particular, it can be heat- treated with a view to tempering. The invention covers both the non-heat-treated glass article and the heat- treated glass article. According to a particular embodiment of the invention, the glass article has both antimicrobial properties and tempered glass properties. A glass having a tempered glass property is understood to mean a glass which has increased mechanical strength in comparison with a conventional non-tempered glass of the same thickness and same composition .
The glass article according to the invention can be obtained according to a method including two main steps :
(a) the partial and/or complete inclusion of the nanoparticles in the mass of the glass close to said surface; and
(b) the deposition and diffusion of the antimicrobial agent beneath the surface of the glass.
Various methods known per se may be suitable for partially and/or completely including the nanoparticles in the mass of the glass. In particular, one exemplary method includes (a) the production of the nanoparticles, (b) the deposition of the nanoparticles on the surface of the article, and (c) the input of energy into the nanoparticles and/or at said surface such that the nanoparticles diffuse/are incorporated into the glass. The formation and deposition of the nanoparticles on the surface of the glass can be carried out in a single step by known methods such as chemical vapor deposition (or CVD) , wet deposition such as sol-gel deposition, for example, or flame-assisted spraying (or flame spraying) using a liquid, gas or solid precursor.
In the flame-assisted spraying, which is mentioned by way of example and disclosed in particular in patent application FI954370, the nanoparticles are generated by atomizing a solution of at least one chemical precursor into an aerosol transported into a flame where combustion occurs in order to form solid nanoparticles. These nanoparticles can next be deposited directly onto a surface placed in proximity to the end of the flame.
Alternatively, the formation and deposition of the nanoparticles on the surface of the glass article can be carried out successively in two steps. In this case, the nanoparticles are generated in advance in solid form or in the form of a suspension in a liquid by a vapor method, wet method (sol-gel, precipitation, hydrothermal synthesis,...) or by a dry method (mechanical grinding, mechanochemical synthesis,...). An example of a method enabling nanoparticles in solid form to be generated in advance is the method known by the name of combustion chemical vapor condensation (or CCVC) . This method consists in converting a precursor solution into a vapor phase in a flame, which undergoes a combustion reaction in order to provide nanoparticles which are ultimately collected.
Next, the pre-generated nanoparticles can be transferred onto the surface of the glass by various known methods.
The energy required for diffusing/incorporating the nanoparticles into the mass of the glass, for example, can be provided by heating the glass or the surface thereof to a suitable temperature. The energy required for diffusing/incorporating the nanoparticles into the mass of the glass can be provided at the moment when the nanoparticles are deposited or later. Flame-assisted spraying is particularly advantageous in this case because the energy required for diffusing/incorporating the nanoparticles into the mass of the glass is provided at the moment when the nanoparticles are deposited by the heat of the flame itself .
According to a particular embodiment of the invention, the method for obtaining a glass article is characterized in that the partial and/or complete inclusion of the nanoparticles includes heating the glass substrate so as to provide the energy required for diffusing/incorporating the nanoparticles into the mass of the glass substrate.
According to a particular embodiment of the invention, the method for obtaining a glass article is characterized in that the partial and/or complete inclusion of nanoparticles is carried out by flame- assisted spraying, so as to provide the energy required for diffusing/incorporating the nanoparticles at the moment when the nanoparticles are deposited.
International patent applications WO2008/132173 Al and WO2010/046336 Al describe the incorporation of aluminum oxide nanoparticles into glass according to a single-step method by means of a flame-assisted spraying technique using an aluminum salt. The nanoparticles of the glass article according to the invention are advantageously obtained according to such a method.
Various methods known per se may be adequate for obtaining an antimicrobial agent diffused beneath the surface of a glass article. In particular, it is possible to deposit an antimicrobial agent in the form of a layer by pyrolytic spray deposition or vacuum cathode sputtering, followed by a controlled slight diffusion of the antimicrobial agent beneath the surface, e.g., for 30 minutes at a temperature of 250°C. The two steps of depositing the antimicrobial agent and diffusing same beneath the surface can likewise be almost simultaneous if the glass article or surface thereof is preheated.
The glass article according to the invention can advantageously be obtained in a single main step by means of a flame-assisted spraying technique using a solution of a salt of the inorganic compound and a salt of the antimicrobial agent.
According to a particular embodiment of the invention, the method for obtaining a glass article is characterized in that the partial and/or complete inclusion of nanoparticles includes the deposition of at least one salt of the inorganic compound on at least one surface of the glass substrate.
According to a particular embodiment of the invention, the method for obtaining a glass article is characterized in that the deposition of at least one salt of the inorganic compound and the deposition of the antimicrobial agent are carried out at least partially simultaneously using a solution of at least one salt of the inorganic compound and at least one salt of the antimicrobial agent.
Due to its antimicrobial properties and to the fact that it can be heat-tempered without adversely affecting said properties, the glass article according to the invention has numerous uses. To illustrate, it can be used as a container for consumable goods or as a bathroom, kitchen or laboratory element (mirror, partition, floor, work surface, door) . It can likewise be used as an appliance element such as refrigerator shelving or oven doors. It likewise has numerous uses in the hospital environment.
The following examples illustrate the invention, without intending to limit the coverage thereof in any way.
Example 1 (comparative)
Three sheets of sodocalcic-type clear float glass having a thickness of 4 mm and dimensions of 20 cm x 20 cm were washed successively with piped-in water, deionized water and isopropyl alcohol and finally dried. They were then coated with a thin layer of silver using the vacuum deposition method, also referred to as magnetron cathode sputtering, in a manner known per se, using a silver metal target in an argon atmosphere. The amount of silver deposited is 40 mg/m 2 of surface treated. In order to diffuse the silver beneath the surface, the three sheets of glass were then heat-treated under the following conditions (time and temperature) :
- sheet 1: 250°C for 30 minutes;
- sheet 2: 400°C for 30 minutes;
- sheet 3: 650°C for 30 minutes.
The treated sheets were finally washed with acid (a solution of HNO 3 and Fe( 0 3 ) 3 ) to eliminate the excess silver remaining on the surface and therefore not having diffused during the heat treatment) .
The sheets of glass treated as described above where analyzed by secondary ion mass spectrometry.
Figure 1 shows the amount of silver (ratio of intensities I (CsAg) /I (CsSi) ) diffused beneath the surface of the glass in relation to the depth (d) in the substrate for each of the heat treatments (a) , (b) and (c) . In addition, the amount of silver at the surface (d = 0) was estimated on the basis of the ratio I (CsAg) /I (CsSi) obtained by dynamic SIMS. I (CsAg) is the peak intensity obtained for the CsAg + ions and I (CsSi) is the peak intensity obtained for the CsSi + ions after bombardment of the surface of the substrate with a beam of Cs + ions using a "Cameca ims-4f" type device (beam of 5.5 keV and angle of incidence of 42° relative to normal to the substrate) . These analyses show the drastic effect of the temperature, for a single treatment time, on the amount of silver present at the surface of the glass. The ratios of intensities I (CsAg) /I (CsSi) determined at the surface (d = 0) are indeed as follows:
- sheet 1: 0.037
- sheet 2: 0.011
- sheet 3 : 0.
Treatment at a temperature of 400°C or 650°C results in a very significant migration of the silver from the surface towards the mass of the glass, with a maximum centered near 1 micrometer. The silver situated at this distance from the surface is no longer available to serve its antimicrobial function and is therefore lost. The effect of the treatment at 650°C is so negative that the amount of silver present at the surface of the glass is practically zero.
Example 2 (comparative)
A sheet of sodocalcic-type clear float glass having a thickness of 4 mm and dimensions of 20 cm x 20 cm was washed successively with piped-in water, deionized water and isopropyl alcohol and finally dried .
Hydrogen and oxygen were introduced into a pinpoint burner so as to generate a flame at the outlet of said burner. A solution containing silver nitrate, Ag 03 dissolved in water (dilution ratio by weight of aluminum/water = 1/2419, solution flow = 10 ml/min) was introduced into the flame. The washed sheet of glass was preheated in a furnace at a temperature of 600°C and one of the surfaces thereof was placed beneath the burner in proximity to the end of the flame, at a distance of 130 mm. In order to cover the entire surface of the sheet of glass, the pinpoint burner is movable in both directions of the space contained in the plane of said sheet. The head of the burner moved continuously in one of the two directions at a speed set at 3 meters per minute and, in the other direction, perpendicular to the first, with skips of 2 centimeters. After this treatment, the sheet of glass was then cooled in a controlled manner.
The sheet of glass treated as described above was analyzed by secondary ion mass spectrometry.
Figure 2 shows the amount of silver diffused (ratio of intensities I (CsAg) /I (CsSi) on a logarithmic scale) in relation to the depth (d) in the sheet of glass from the treated surface. It shows the diffusion of the silver beneath the surface of the glass. The concentration of silver is distributed over a depth greater than 1 micrometer according to a profile which has a minimum at a depth of approximately 15 nm from the surface. In addition, the ratio of intensities I (CsAg) /I (CsSi) at the surface is 0.002.
Example 3 (according to the invention)
A sheet of sodocalcic-type clear float glass having a thickness of 4 mm and dimensions of 20 cm x 20 cm was washed successively with piped-in water, deionized water and isopropyl alcohol and finally dried .
Hydrogen and oxygen were introduced into linear burner so as to generate a flame at the outlet of said burner. The width of the burner used was 20 cm and it included 2 spraying booms for the introduction of the precursor solution. The washed sheet of glass was preheated in a furnace at a temperature of 600 °C and then moved at this temperature at a speed of approximately 8 m/min beneath the burner positioned above the sheet of glass at a distance of 90 mm. The solution introduced into the flame by means of nozzles contained silver nitrate, Ag 03 dissolved in water (dilution ratio by weight of silver/water = 1/3500) and aluminum nitrate nonahydrate, Al (NO 3 ) 3.9¾0 dissolved in methanol (dilution ratio by weight of aluminum/methanol = 1/20) . The total flow of the solution was 360 ml/min. After this treatment, the sheet of glass was then cooled in a controlled manner.
The sheet of glass treated as described above was analyzed by scanning transmission electron microscopy, X-ray fluorescence spectrometry, X-ray photoelectron spectroscopy and secondary ion mass spectrometry.
The analyses carried out showed that the aluminum was incorporated into the mass of the glass close to the surface, in the form of nanoparticles of aluminum oxide AI 2 O 3 . The nanoparticles are primarily crystalline and have a size which varies from 10 to 100 nm.
Figure 3 shows the ratio of intensities I (CsAg) /I (CsSi) (logarithmic scale) in relation to the depth (d) in the sheet of glass from the treated surface. It shows the diffusion of the silver beneath the surface of the glass. The concentration of silver is distributed in the depth of the glass according to a profile which has a maximum value at the surface, a gradual decrease up to a minimum centered near 200 nm, followed by a slight increase ending in a plateau at approximately 0.8 micrometers. In addition, the ratio I (CsAg) /I (CsSi) at the surface (maximum profile value) is 0.015, which shows that, using a single method to diffuse the silver, the presence of nanoparticles enables a much higher concentration of silver to be obtained at the surface of the glass, which is favorable to the antimicrobial activity. Example 4 (according to the invention)
An article according to the invention was produced in a plant intended for continuous manufacturing of sodocalcic-type flat glass. This plant includes a melting furnace, a tin bath and a cooling gallery. The glass, in the molten state, was poured, in the form of a ribbon coming from the melting furnace, onto the tin bath. The ribbon of glass had an average thickness of 8 mm. It was then moved at a constant speed of approximately 7.75 m/min and at a temperature of 615°C towards a linear burner measuring 20 cm wide. The burner was supplied with hydrogen and oxygen so as to generate a flame at the output of said burner, and same was positioned above the sheet of glass, at a distance of 145 mm. A solution containing silver nitrate, AgNC>3 dissolved in methanol (dilution ratio by weight of silver/methanol = 1/3500) and aluminum nitrate nonahydrate, Al (NO 3 ) 3.9¾0 dissolved in methanol (dilution ratio by weight of aluminum/methanol = 1/20) was introduced into the flame (total flow of the solution = 343 ml/min) . The sheet of glass was finally moved towards the cooling gallery where it was cooled in a controlled manner under the conditions normally used for flat float glass.
The sheet of glass treated as described above was analyzed using the same techniques as those described in example 3.
The analyses carried out showed that the aluminum was incorporated into the mass of the glass close to the surface, in the form of nanoparticles of aluminum oxide, AI 2 O 3 . The nanoparticles are primarily crystalline and have a size which varies from approximately 5 to 50 nm. Figure 4 shows a slide obtained by transmission electron microscopy of a section of the treated sheet of glass. It shows several aluminum oxide nanoparticles incorporated into the mass of the glass, partially 1 or completely 2.
Figure 5 shows the ratio of intensities I (CsAg) /I (CsSi) (logarithmic scale) in relation to the depth (d) in the sheet of glass from the treated surface. It shows the diffusion of the silver beneath the surface of the glass. The concentration of silver is distributed in the depth of the glass according to a profile which has a maximum value at the surface, a gradual decrease up to a plateau between 150 and 400 nm, followed by a slight increase ending in another plateau from approximately 0.6 micrometers. The ratio I (CsAg) /I (CsSi) at the surface (maximum profile value) for example 4 is 0.010, which once again shows that the presence of nanoparticles enables a higher concentration of silver to be obtained at the surface of the glass.
Example 5 (according to the invention) An article according to the invention is produced in a plant intended for continuous manufacturing of sodocalcic-type printed flat glass. This plant includes a melting furnace, a laminator and a cooling gallery. The glass, in the molten state, was poured, in the form of a ribbon coming from the melting oven, into the laminator where it passed between two stacked rollers, one of which is smooth and the other of which is etched with a printing pattern. This printing pattern was then reproduced on a single surface of the glass, the one turned towards the bottom of the horizontal ribbon. Once having passed through the laminator, the ribbon of glass had an average thickness of approximately 4 mm (3.5 - 4.5 mm) . It was then moved at a constant speed of approximately 3.7 m/min and at a temperature of 710°C towards a linear burner measuring 2 m wide. The burner was supplied with hydrogen and oxygen so as to generate a flame at the output of said burner and same was positioned above the sheet of glass on the unprinted side, at a distance of 120 mm. A solution containing aluminum nitrate nonahydrate, Al (NO 3 ) 3.9¾0 dissolved in methanol (dilution ratio by weight of aluminum/methanol = 1/60, flow = 1,000 ml/mn) was introduced into the flame. The sheet of glass was then moved towards the cooling gallery where it was cooled in a controlled manner, under the conditions normally used for printed flat glass.
The sheet of glass was then coated with a thin layer of silver using the vacuum deposition method, also referred to as magnetron cathode spraying, in a manner known per se, using a silver metal target in an argon atmosphere. The amount of silver deposited is 100 mg/m 2 of treated surface. In order to diffuse the silver beneath the surface, the sheet of glass was then treated at 300°C for 15 minutes, so as to diffuse the silver beneath the surface. The treated sheet was then cleaned with acid (a solution of HNO 3 and Fe( 03) 3 ) to eliminate the excess silver remaining on the surface and therefore not having diffused during the heat treatment.
It was then tempered in a manner known per se, i.e., heated to a temperature of 670°C for 3 minutes and then cooled very quickly to ambient temperature.
The sheet of glass treated as described above was analyzed using the same techniques as those mentioned in example 3.
The analyses carried out showed that the aluminum was incorporated in the form of aluminum oxide particles that were partially or completely incorporated into the mass of the glass. The particles have a quasi-spherical shape and a size which varies from 170 to 850 nm. The particles are primarily crystalline .
Figure 6 shows the ratio of intensities I (CsAg) /I (CsSi) (logarithmic scale) in relation to the depth (d) in the sheet of glass from the treated surface. It shows the diffusion of the silver beneath the surface of the glass. The ratio I (CsAg) /I (CsSi) on the surface (maximum profile value) is 0.0026, which shows that the presence of nanoparticles likewise enables certain concentration of silver to be maintained at the surface, even after tempering (compared to the sample of example 1, without any nanoparticles, and for which the concentration of silver at the surface after a similar heat treatment is zero) .