U.S. patent application number 11/721688 was filed with the patent office on 2011-04-07 for substrate with antimicrobial properties.
This patent application is currently assigned to AGC FLAT GLASS EUROPE S.A.. Invention is credited to Christophe Ego, Andre Hecq, Kadosa Hevesi, Nadia Jacobs, Georges Pilloy, Jean-Pierre Poels, Muriel Tournay.
Application Number | 20110081542 11/721688 |
Document ID | / |
Family ID | 35677434 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110081542 |
Kind Code |
A1 |
Pilloy; Georges ; et
al. |
April 7, 2011 |
SUBSTRATE WITH ANTIMICROBIAL PROPERTIES
Abstract
A process for the production of a substrate having antimicrobial
properties is described. It comprises a step consisting of the
deposition of a metal non-gelling layer comprising an inorganic
antimicrobial agent, starting from a precursor, in metal, colloid,
chelate or ion form on at least one of the surfaces of the glass
substrate; and a step consisting of the diffusion of the agent into
said at least one surface of the substrate by thermal treatment.
Alternatively, the substrate may be coated with an underlayer or a
topcoat and the diffusion occurs either in the underlayer or in the
topcoat. Glass and metallic substrates having antimicrobial
properties are also described. In particular, a substrate
exhibiting a bactericidal activity measured in accordance with
standard JIS Z 2801 of higher than log 2.
Inventors: |
Pilloy; Georges; (Jumet,
BE) ; Ego; Christophe; (Jumet, BE) ; Poels;
Jean-Pierre; (Jumet, BE) ; Tournay; Muriel;
(Villers-La-Ville, BE) ; Hecq; Andre; (Jumet,
BE) ; Hevesi; Kadosa; (Jumet, BE) ; Jacobs;
Nadia; (Jumet, BE) |
Assignee: |
AGC FLAT GLASS EUROPE S.A.
BRUXELLES
BE
|
Family ID: |
35677434 |
Appl. No.: |
11/721688 |
Filed: |
December 16, 2005 |
PCT Filed: |
December 16, 2005 |
PCT NO: |
PCT/EP2005/056883 |
371 Date: |
July 27, 2010 |
Current U.S.
Class: |
428/341 ;
204/192.1; 427/343; 427/383.1; 427/454; 427/455 |
Current CPC
Class: |
C23C 14/5806 20130101;
Y10T 428/273 20150115; C23C 18/08 20130101; C03C 21/008 20130101;
Y10T 428/31678 20150401; C03C 23/0095 20130101; C03C 2217/479
20130101; Y10T 428/12493 20150115; C23C 10/30 20130101; C03C
2217/45 20130101; C03C 21/001 20130101; C23C 14/5893 20130101; C03C
17/34 20130101; A01N 59/16 20130101; C03C 2218/32 20130101; C03C
2204/02 20130101; C23C 10/28 20130101; C03C 2218/154 20130101; C23C
14/16 20130101; A01N 25/08 20130101; C03C 2217/251 20130101 |
Class at
Publication: |
428/341 ;
204/192.1; 427/383.1; 427/455; 427/343; 427/454 |
International
Class: |
B32B 5/00 20060101
B32B005/00; C23C 14/34 20060101 C23C014/34; C23C 14/08 20060101
C23C014/08; C23C 14/14 20060101 C23C014/14; B05D 3/10 20060101
B05D003/10; B05D 1/36 20060101 B05D001/36; C23C 4/10 20060101
C23C004/10; C23C 4/08 20060101 C23C004/08 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 16, 2004 |
EP |
04106648.1 |
Mar 10, 2005 |
EP |
05101882.8 |
Claims
1. Process for the production of a substrate having antimicrobial
properties, characterised in that it comprises the following steps:
(i) deposition of a metal non-gelling layer comprising an inorganic
antimicrobial agent, obtained at the outset from a precursor, in
metal, colloid, chelate or ion form, on at least one of the exposed
surfaces of the substrate; (ii) diffusion of the agent into or
under said at least one exposed surface of the substrate by thermal
treatment at a temperature comprised between 200 and 750.degree.
C.
2. Process according to claim 1, characterised in that the
temperature of the thermal treatment is (i) lower than 450.degree.
C., (ii) lower than 380.degree. C., or (iii) lower than 350.degree.
C.
3. (canceled)
4. Process according to claim 1, characterised in that the
temperature of the thermal treatment is (i) higher than 200.degree.
C., (ii) higher than 220.degree. C., or (iii) higher than
240.degree. C.
5. Process according to claim 1, characterised in that the
diffusion of the agent by thermal treatment is realized during a
tempering step.
6. Process according to claim 1, characterised in that the thermal
treatment is conducted for a period in the range of (i) between 2
minutes and 2 hours, (ii) between 6 minutes and 1 hour, and iii)
between 8 and 40 minutes.
7. Process according to claim 1, characterised in that the thermal
treatment is conducted at a temperature in the range of between
200.degree. and 350.degree. C. for a period varying from 10 to 30
minutes.
8. Process according to claim 1, characterised in that the
precursor used in step (i) is (a) in a metallic form, or (b) in
ionic form and dissolved in an aqueous solution.
9. Process according to claim 1, characterised in that the layer
comprising the antimicrobial agent is deposited either by pyrolytic
spraying, vacuum sputtering or by a method involving the
precipitation of metal antimicrobial agents by reduction of a
corresponding salt.
10. Process according to claim 1, characterised in that the
antimicrobial agent is selected from silver, copper and zinc.
11. Process according to claim 1, characterised in that the
quantity of antimicrobial agents deposited on said at least one
surface of the substrate is (i) more than 5 mg/m.sup.2, (ii) more
than 10 mg/m.sup.2, or (iii) more than 20 mg/m.sup.2.
12. Process according to claim 1, characterised in that the
substrate is coated with an undercoat before the deposition of step
(i), and in that the diffusion of step (ii) occurs mainly within
the coating.
13. Process according to claim 12, characterised in that the
undercoat comprises a first underlayer, having the function of
blocking or slowing down the migration of the antimicrobial agent,
and a second underlayer, serving as a reservoir for the
antimicrobial agents.
14. Process according to claim 13, characterised in that the
blocking underlayer is chosen amongst (i) pyrolitic and sputtered
layers, or (ii) layers comprising metal oxide, metal or metal alloy
compound, such as Pd, Ni--Cr, TiOx, NiCrOx, Nb, Ta, Al, Zr or ZnAl,
or mixtures thereof.
15. Process according to claim 13, characterised in that the
undercoat comprises a first layer based on ZrO.sub.2 and a second
layer based on TiO.sub.2, in particular in the anatase crystallised
form.
16. Process according to claim 1, characterised in that the
substrate is a glass type substrate, in particular a clear
soda-lime glass.
17. Process for the production of a substrate having antimicrobial
properties, characterised in that it comprises the following steps:
(i) deposition of a metal non-gelling layer comprising an inorganic
antimicrobial agent, obtained at the outset from a precursor, in
metal, colloid, chelate or ion form, on at least one of the
surfaces of the substrate; (ii) deposition of a top coat (iii)
diffusion of the agent in said topcoat by thermal treatment at a
temperature comprised between 200 and 750.degree. C.
18. Substrate comprising an antimicrobial agent present at least
one of its exposed surfaces, characterised in that the total
quantity of antimicrobial agents it comprises is (i) more than 0.1
mg/m.sup.2, (ii) more than 1 mg/m.sup.2, or (iii) more than 10
mg/m.sup.2 of antimicrobial surface.
19. Substrate according to claim 18, characterised in that on at
least one of the following bacteria: E. coli, S. aureus, P.
aeruginosa (measured in accordance with the standard JIS Z 2801),
the antimicrobial agent has a bactericidal effect (i) higher than
log 1, (ii) higher than log 2, or (iii) higher than log 2.5.
20. Substrate according to claim 18, characterised in that it has
an antimicrobial effect after at least one of the following
accelerated ageing tests: wet spray (test for 20 days in a chamber
with a humidity of more than 95% and at 40.degree. C.), 500 hours
of UV irradiation (4 340A ATLAS lamps, chamber at 60.degree. C.),
after 24 hours immersed in a solution of H.sub.2SO.sub.4 (0.1 N),
after 24 hours immersed in a solution of NaOH (0.1 N).
21. Substrate according to claim 18, characterised in that the
antimicrobial agent is selected from silver, copper and zinc.
22. Substrate according to claim 18, characterised in that it is
glass substrate.
23. Glass substrate according to claim 18, characterised in that it
comprises an antimicrobial agent present at at least one of its
exposed surfaces, such that the ratio I(CsAg)/I(CsSi) (measured in
the surface using the dynamic SIMS method) is (i) higher than
0.015, (ii) higher than 0.020, or (iii) higher than 0.025.
24. Glass substrate according to claim 22, characterised in that it
has a neutral coloration in reflection, i.e. the colorimetric
indexes a* and b* are in the range of (i) between -10 and 6, (ii)
between -5 and 3, or (iii) between -2 and 0, and the purity is (a)
less than 15%, (b) less than 10% or (c) less than 5%.
25. Glass substrate according to claim 22, characterised in that it
has a visible integrated light absorption of (i) less than 1.5%,
(ii) less than 1.4%, or (iii) less than 1.3%.
26. Glass substrate according to claim 22, characterised in that it
presents annealed characteristics.
27. Annealed glass substrate comprising antimicrobial agents
present at least one exposed glass surface.
28. Process according to claim 7, characterised in that the layer
comprising the antimicrobial agent is deposited either by pyrolytic
spraying, vacuum sputtering or by a method involving the
precipitation of metal antimicrobial agents by reduction of a
corresponding salt.
Description
[0001] The present invention relates to a Substrate, in particular
glass-type substrate or metallic substrate, wherein at least one of
its surfaces has antimicrobial, in particular antibacterial or
antifungal, properties. The present invention also relates to a
process for the production of such a substrate.
[0002] In the field of ceramic substrates, EP 653 161, for example,
describes the possibility of covering these with a glaze composed
of silver to provide them with antibacterial properties.
[0003] In the field of glass-type substrates, sol-gel type
processes are known to provide an antimicrobial surface. These
processes require a hardening stage of the sol-gel layer, which
involves elevated temperatures in the order of
500.degree.-600.degree. C. (sintering temperature). Processes are
also known that require the substrate to be dipped in a composition
comprising a silver salt. In this case, a silver layer is not
deposited, but an ion exchange takes place in the solution at an
elevated temperature.
[0004] A process for producing a glass substrate having
antimicrobial properties is also known from EP 1449816. This
process requires both a drying stage between 20.degree. and
105.degree. C. and a thermal treatment at 600.degree.-650.degree.
C. This thermal treatment has some disadvantages particularly with
respect to cost and uniformity of the product. Moreover, it renders
the process very poorly reproducible, since it has been found that
at these temperatures the diffusion of the silver is very rapid and
a slight variation in the duration of the thermal treatment results
in a significant variation in the depth of diffusion of the silver,
and therefore this causes variation in the antibacterial properties
of the substrate. It may also be noted that such a thermal
treatment causes an undesirable yellow colouration of a soda-lime
glass substrate. Furthermore, with this process, after having been
treated, the product may no more be cut into particular size
because of the necessary tempering process.
[0005] Therefore, there is a need to provide a substrate, either
glass or metallic, with antimicrobial properties, which is easy to
use and inexpensive to produce.
[0006] According to one embodiment, the present invention relates
to a process for the production of a substrate (in particular glass
or metallic substrate) having antimicrobial properties,
characterised in that it comprises the following steps:
[0007] (ii) diffusion of the agent into or under said at least one
surface of the substrate by thermal treatment at a temperature
comprised between 200 and 750.degree. C.
[0008] According to another embodiment, the process is
characterised in that it comprises the following sequential steps:
[0009] (i) deposition of a metal non-gelling layer comprising an
inorganic antimicrobial agent, obtained at the outset from a
precursor, in metal, colloid, chelate or ion form, on at least one
of the surfaces of the substrate; [0010] (ii) deposition of a
topcoat; [0011] (iii) diffusion of the agent in said topcoat by
thermal treatment at a temperature comprised between 200 and
750.degree. C.
[0012] During the thermal treatment, the antimicrobial agent can
diffused under the surface, toward the centre of the substrate, if
no coating is applied or in an undercoat, or in a topcoat, in case
those coating are applied on the substrate.
[0013] If an undercoat is applied, it can advantageously comprise a
first layer, having the functions of blocking or slowing down the
migration of the antimicrobial agent and a second layer serving as
a reservoir for the antimicrobial agents. Those functions can be
ascertained on a product made according to the invention by
comparing the antimicrobial effect of similar products with and
without undercoating and/or by analysing diffusion profiles (see
FIGS. 1 and 2).
[0014] Each layer of the undercoat may in particular have a
thickness comprised between 5 and 1000 nm, preferably between 8 and
800 nm, most preferably between 10 and 600 nm.
[0015] The substrate may be a sheet of flat glass, particularly
soda-lime glass which may be float glass. It may be clear glass.
The glass may have a thickness within the range of 2.5 to 12 mm. It
may be clear glass or coloured glass. It may comprise a reflective
layer (to form a mirror) or a layer of enamel or painting (for wall
covering), generally at the surface opposite to the antimicrobial
surface.
[0016] The substrate may have a surface area of greater than 0.8 m
to 0.8 m; it may be adapted to be cut to a finished size by a
subsequent cutting operation.
[0017] When the substrate is a clear soda-lime glass, according to
one preferred embodiment, the maximum temperature of the heat
treatment is preferably the glass transition temperature which is
in the order of 550.degree. C. Advantageously, the temperature of
the thermal treatment is lower than 450.degree. C., preferably
lower than 380.degree. C. and particularly preferred lower than
350.degree. C., and advantageously higher than 200.degree. C.,
preferably higher than 220.degree. C. and particularly preferred
higher than 240.degree. C.
[0018] The duration of the thermal treatment must be adjusted in
accordance with the selected temperature. In particular, it is
found that a duration in the range of between 2 minutes and 2 hours
may be appropriate, preferably between 5 minutes and 1 hour, and
particularly preferred between 7 and 40 minutes.
[0019] A particularly advantageous temperature-duration combination
has proved to be a temperature in the range between 200.degree. and
350.degree. C. over a period varying from 10 to 30 minutes.
[0020] The antimicrobial agent can be selected from various
inorganic agents known for their antimicrobial properties, in
particular silver, copper and zinc. Advantageously, the
antimicrobial agent is in metallic form.
[0021] The process according to the invention advantageously
comprises an additional step (iii), which consists of eliminating
any excess antimicrobial agent remaining on the surface, i.e. that
has not diffused during the thermal treatment step (ii). This
elimination can be achieved by washing. In particular, solutions
based on HNO.sub.3, FeCl.sub.3 or Fe(NO.sub.3).sub.3 are suitable
for such a washing process. This washing can prevent any
antimicrobial agents from remaining on the surface in metallic form
in such a quantity that they could cause the treated surface to
become too reflective. For some applications, it is preferred that
the substrate treated according to the invention does not exhibit
any significant increase in light reflection (LR), or any
significant reduction in light transmission (LT) in relation to the
untreated substrate.
[0022] It has been found that with the process according to the
invention, a very low quantity of antimicrobial agent can be
deposited on said at least one surface of the substrate. In some
cases, a quantity of more than 5 mg/m.sup.2, preferably more than
20 mg/m.sup.2 and particularly preferred more than 35 mg/m.sup.2 of
surface to be treated can be appropriate. However, the use of much
higher concentrations (800 or 900 mg/m2) does not impede the
result, instead such concentrations have proved to be simply
unnecessary and can require excess to be eliminated on a much more
significant scale.
[0023] Various methods known per se can be suitable for depositing
the layer comprising the antimicrobial agent. In particular,
deposition is possible by pyrolytic spraying, by sputtering or by a
method similar to the method used for the production of mirrors,
which comprises spraying of a salt of an antimicrobial agent such
as AgNO.sub.3 and precipitation by reduction of the antimicrobial
agent in metal form.
[0024] Various types of glass substrate can be considered,
depending on the applications sought. In addition to the
traditional clear soda-lime float glass, glass that is coloured,
frosted or patterned etc. can also be used. The glass sheets can be
treated on one or on both their faces. The face opposite the
treated face can be subjected to any desired type of surface
treatment. For example, a coating of paint or enamel or a
reflective layer can be applied thereon, e.g. for applications such
as wall coverings or mirrors.
[0025] The invention also relates to a glass substrate comprising
an antimicrobial agent present at or diffused into or under at
least one of its exposed surfaces, such that the ratio
I(CsAg)/I(CsSi) in the surface (measured according to the dynamic
SIMS method) is higher than 0.015, preferably higher than 0.020 and
particularly preferred higher than 0.025. The quantity of
antimicrobial agents present or diffused into at least one of its
surfaces is advantageously more than 0.1 mg/m.sup.2, preferably
more than 1 mg/m.sup.2 and particularly preferred more than 10
mg/m.sup.2 of antimicrobial surface.
[0026] The I(CsAg)/I(CsSi) ratio is measured using a Cameca ims-4-f
apparatus. I(CsAg) is the peak intensity obtained for the
CsAg.sup.+ ions and I(CsSi) is the peak intensity obtained for
CsSi.sup.+ ions after bombardment of the surface of the substrate
by a Cs.sup.+ ion beam, which progressively scours the surface of
the sample. The energy of the Cs.sup.+ ion beam reaching the
substrate is 5.5 keV. The angle of incidence of the beam is
42.degree. to the normal of the substrate. The surface values
indicate that the values are taken for as small a depth as
possible, as soon as the value obtained is significant. Depending
on the erosion rate used, the first significant values can
correspond to maximum depths of about 1 to 5 nm. In the present
case, the surface values correspond to a maximum depth of 2 nm. To
ensure that the values obtained are significant, the ratio of
isotopes Ag107/Ag109 must in particular be close to the theoretical
value (1.0722), in particular be in the range of between 1.01 and
1.13.
[0027] In some embodiments of the invention, a substrate having
antimicrobial agents present at least one exposed surface may be an
annealed sheet of glass. The term annealed sheet of glass is used
herein to mean that the glass may be cut to size without breaking
in the way that a tempered or hardened sheet of glass would break
upon cutting. Such an annealed sheet of glass preferably has a
surface compression of less than 5 MPa.
[0028] The invention also relates to metallic or other substrates
comprising antimicrobial agents present at or diffused into or
under at least one of its exposed surface at an atomic % preferably
greater than 1% more, preferably greater than 1.5%, most preferably
greater than 2%.
[0029] The substrate according to the invention has an
antibacterial effect on a large number of bacteria, whether gram
positive or gram negative bacteria, in particular on at least one
of the following bacteria: Escherichia coli, Staphylococcus aureus,
Pseudomonas aeruginosa, Enterococcus hirae. The antibacterial
effect measured in accordance with the standard JIS Z 2801 is in
particular, at least on any one of these bacteria, higher than log
1, preferably higher than log 2 and particularly preferred higher
than log 2.5. The substrate will be considered bactericidal
according to the standard HS Z 2801 if it has an effect higher than
log 2. However, the invention also relates to substrates that have
a lesser effect (for example a bacteriostatic effect, which means
that the bacteria are not necessarily killed but can not developed
anymore).
[0030] The substrate according to the invention advantageously has
an antifungal (fungicidal or fungistatic) effect on any one fungus,
in particular Candida albicans or Aspergillus niger.
[0031] When the glass substrate used is a clear glass, it can
advantageously have antimicrobial properties as well as a neutral
colouration in reflection. In particular, the colorimetric indexes
(CIELAB system) in reflection a* and b* (Illumiant C, 10.degree.
observer) are in the range of between -10 and 6, preferably between
-5 and 3 and particularly preferred between -2 and 0, and the
purity may be less than 15%, preferably less than 10% and
particularly preferred less than 5%.
[0032] If the substrate is a coloured glass, it can be considered
that antimicrobial properties may be obtained without changing very
much the initial colour of the substrate. The change of coloration
is generally expressed with the colorimetric index by Delta E*;
DeltaE*=[(1*.sub.1-1*.sub.2).sup.2+(a*.sub.1-a*.sub.2).sup.2+(b*.sub.1-b*-
.sub.2).sup.2].sup.1/2. A DeltaE*lower than 3, preferably lower
than 2 may be obtained for an antimicrobial substrate according to
the invention.
[0033] When the glass substrate used is a clear glass, it can
advantageously have both antimicrobial properties and a visible
light absorption of less than 1.5%, preferably less than 1.4% and
particularly preferred less than 1.3%. It may have a visible light
transmission within the range of 80 to 91%, preferably 84 to 90%.
And the visible light reflection may be less than 15%, preferably
less than 12%, most preferably less than 10%.
[0034] The substrate according to the invention preferably has in
particular an antimicrobial effect after any one of the following
accelerated ageing tests: wet spray test (test over 20 days in a
chamber with a humidity of more than 95% at 40.degree. C.), after
500 hours of UV irradiation (4 340A ATLAS lamps, chamber at
60.degree. C.), after 24 hours immersed in a solution of
H.sub.2SO.sub.4 (0.1 N), after 24 hours immersed in a solution of
NaOH (0.1 N).
[0035] Preferred or alternative embodiments of the present
invention are described in dependant claims.
[0036] The present invention shall be described in more detail
below, in a non-restrictive manner, with reference to the attached
drawings:
[0037] FIGS. 1a to 1h show diffusion profiles of silver into the
surface of the substrate for samples obtained using the procedure
of Example 1 (deposition of the silver layer by spraying);
[0038] FIG. 2 shows a diffusion profile of silver into the surface
of the substrate for a sample obtained using the procedure of
Example 2 (deposition by precipitation of a silver layer by
reduction of the corresponding salt).
EXAMPLE 1
Production of Antimicrobial Samples
[0039] Samples of clear soda-lime glass were coated with a silver
layer using the vacuum deposition method, also referred to as
magnetron sputtering, in a manner known per se using a silver metal
target in an atmosphere of argon. The quantity of silver deposited
was 40 mg/m.sup.2 of surface treated for sample 1.a (4 mm thick
glass) and 100 mg/m.sup.2 of surface treated for samples 1.b to 1.e
(2 mm thick glass).
[0040] To cause the silver to diffuse into the surface, the samples
were then subjected to a thermal treatment in the conditions
(duration and temperature) specified in Table 1.
[0041] The treated samples were then washed in acid to eliminate
any excess silver remaining in the surface that had therefore not
diffused during the thermal treatment. The aim is to eliminate any
trace of silver on the surface (mainly metallic Ag) and thus obtain
a clear glass without eliminating the silver that has lightly
diffused into the surface. Solutions of HNO.sub.3, FeCl.sub.3 or
Fe(NO.sub.3).sub.3 are suitable for such a washing process.
[0042] FIGS. 1.a to 1.e show the quantity of silver diffused into
the surface of the substrate as a function of the depth (d) in the
substrate. The quantity of silver is estimated by measuring the
I(CsAg)/I(CsSi) ratio obtained by dynamic SIMS. I(CsAg) is the peak
intensity obtained for the CsAg.sup.+ ions and I(CsSi) is the peak
intensity obtained for the CsSi.sup.+ ions after bombardment of the
surface of the substrate by a Cs.sup.+ ion beam using a Cameca
ims-4-f apparatus (beam of 5.5 keV and angle of incidence of
42.degree. to the normal of the substrate).
[0043] Measurement of the Antimicrobial Effect
[0044] The bactericidal and fungicidal properties of some samples
were analysed in accordance with standard JIS Z 2801. The results
are collated in Table 1 below.
[0045] A log 1 level indicates that 90% of the bacteria inoculated
onto the surface of the glass were killed in 24 hours in the
conditions of the standard; log 2 indicates that 99% of the
bacteria were killed; log 3 indicates that 99.9% of the bacteria
deposited were killed, etc.
TABLE-US-00001 TABLE 1 Temperature Duration Diffusion I(Cs/Ag)/
Bacterium or Antimicrobial Examples .degree. C. (minutes) Profile
I(Cs/Si) fungus tested effect 1.a 250 15 FIG. 1.a 0.200 E. coli
>log 4.sup. 1.b 250 30 FIG. 1.b 0.037 E. coli >log 4.sup. 1.c
300 15 FIG. 1.c 0.027 E. coli log 3.6 S. aureus log 3.4 P.
aeruginosa log 4.1 E. hirae log 1.0 C. albicans log 1.2 1.d 350 15
FIG. 1.d 0.027 1.e 400 15 FIG. 1.e 0.021 E. coli log 1.6
[0046] Sample 1.a has an appearance that is neutral in reflection.
The colorimetric indexes are a*=-0.2 and b*=-0.9 and the purity is
1.9%. Sample 1.c also has an appearance that is neutral in
reflection. The colorimetric indexes are a*=-0.2 and b*=-0.7 and
the purity is 1.5% (measured with illuminant D, angle of
10.degree.).
[0047] Accelerated ageing tests were conducted on sample 1.c, which
showed that the antimicrobial effect survived. An antibacterial
effect with respect to E. coli of higher than or equal to log 4 was
measured after the following artificial ageing tests: [0048] wet
spray (test for 20 days in a chamber with a humidity of more than
95% and at 40.degree. C.); [0049] after 500 hours of UV irradiation
(4 340A ATLAS lamps, chamber at 60.degree. C.), [0050] after 24
hours immersed in an H.sub.2SO.sub.4 solution (0.1 N), [0051] after
24 hours immersed in an NaOH solution (0.1 N).
EXAMPLE 2
[0052] Samples of clear soda-lime glass 4 mm thick were coated with
a silver layer by chemical deposition using a method similar to
that used to produce mirrors.
[0053] The samples were firstly subjected to a step of
sensitisation using tin chloride solution. An aqueous solution of
AgNO.sub.3 was then sprayed onto the surface of the glass at a flow
rate of 200 ml/min along with a reducing agent to reduce the silver
salt into metallic silver. The excess was then rinsed off.
Quantities of 100 to 800 mg of Ag/m.sup.2 were deposited onto one
face of the glass substrates.
[0054] To cause the silver to diffuse into the surface, the
different samples were then subjected to different thermal
treatments for a period of 10 to 30 minutes at temperatures varying
from 250.degree. to 350.degree. C. (see Table 2).
[0055] The treated samples were then washed in acid to eliminate
the excess silver remaining in the surface as in Example 1.
[0056] The diffusion profile of sample 2.d is shown in FIG. 2.
[0057] The antimicrobial effect was analysed using the same method
as in Example 1 and the results are collated in Table 2 below.
TABLE-US-00002 TABLE 2 Concentration of Temperature and Ag
deposited duration of I(CsAg)/ Bacte- Antimicrobial Examples
(mg/m.sup.2) thermal treatment I(CsSi) rium effect 2.a 100
250.degree. C., 15 min 0.15 E. coli >log 4.8 2.b 100 300.degree.
C., 15 min 0.14 E. coli >log 4.8 2.c 100 350.degree. C., 10 min
0.075 E. coli >log 4.8 2.d 250 300.degree. C., 15 min 0.021 E.
coli >log 3.6 2.e 300 250.degree. C., 15 min 0.22 E. coli log
4.8 2.f 300 300.degree. C., 15 min 0.23 E. coli log 4.8 2.g 300
350.degree. C., 10 min 0.13 E. coli >log 4.8
EXAMPLE 3
[0058] Samples of clear soda-lime glass 6 mm thick were coated with
a layer of silver by means of pyrolytic spraying. A solution of
AgNO.sub.3 was sprayed for 5 seconds onto samples preheated at
temperatures from 300.degree. to 400.degree. C. The solution
pyrolysed on contact with the hot substrate and formed a film of
metallic silver.
[0059] In this case, the two steps of depositing the antimicrobial
agent and its diffusion into the surface were virtually
simultaneous since the substrate was preheated. In this case, the
process could be used during the continuous production of float
glass. The spraying of silver could be arranged after the tin bath
and could be conducted either before the ribbon of glass enters the
annealing lehr or in the actual annealing lehr.
[0060] The treated glass was then washed as in Examples 1 and
2.
EXAMPLE 4
[0061] Samples of clear soda-lime glass were coated with one or two
layers of different metal oxides or oxycarbides with a thickness
varying between 13 and 500 inn, using pyrolytic deposition. The
nature and thicknesses of the layers are collated in Table 3
below.
[0062] A layer of silver (100 to 500 mg/m.sup.2) was deposited on
the last layer of the substrate and a tempering thermal treatment
was applied (temperature: 680.degree. C., duration 6 minutes).
TABLE-US-00003 TABLE 3 Concentration of Ag Antibacterial Substrate
deposited (mg/m.sup.2) Bacterium effect (log) Glass/TiO.sub.2 (45
nm) 100 E.coli 1.6 300 E.coli 2.2 Glass/SiOxCy (70 nm) 100 E.coli
4.8 500 E.coli 4.8 Glass/SnO.sub.2:F (500 nm) 100 E.coli 1.1
Glass/SiOxCy (75 nm)/ 100 E.coli >4.8 SnO.sub.2:F (300 nm) 500
E.coli >4.8 Glass/SiO.sub.2 (25 nm)/ 100 E.coli 3.5 TiO.sub.2
(13 nm) 500 E.coli 4.3
[0063] The bactericidal properties of the samples were analysed in
accordance with standard JIS Z 2801. The results are collated in
Table 3 above.
[0064] It is noted that, as a result of the layer or layers firstly
deposited on the substrate, the antimicrobial effect is retained
despite the thermal treatment at high temperature. Therefore, a
product is obtained that has both the advantages of a tempered
glass and of an antimicrobial glass.
[0065] The presence of the coating layer may reduce the variability
of the antimicrobial effect of the finished product to variations
in the heat treatment process. In addition, it may provide a
surface or material that is better adapted to contain the
antimicrobial agent that the surface of the substrate.
[0066] For simplicity, it is also possible to conduct the tempering
step at a later stage. To be able to preserve the substrates prior
to tempering, it is thus recommended that a first thermal treatment
is conducted at low temperature and for a short period (e.g. from
250.degree. to 400.degree. C. for 5 to 30 minutes) in order to
cause the antimicrobial agent to diffuse into the layer or layers.
The result is a glass sheet that can be cut to a desired size and
then tempered in a subsequent process.
EXAMPLE 5
[0067] A sample of clear soda-lime glass pyrolytically coated with
a first layer of SiOx (75 nm) and a second layer of SnO2 doped with
Fluorine (320 nm) was used. A silver layer of 100 mg/m2 was
deposited by the vacuum deposition method as in example 1 using a
silver target in an argon atmosphere.
[0068] The coated samples were subjected to a tempering process
(670.degree. C. during 10 minutes).
[0069] The bactericidal properties of the sample was analysed in
accordance with standard JIS Z 2801. A log 2.58 was obtained. This
indicates that good bactericide properties were obtained
simultaneously with tempering characteristics.
EXAMPLE 6
[0070] A sample of clear soda-lime glass coated by vacuum
sputtering with the following stack of layers: Glass/ZnSnOx (10
nm)/NiCr (80-20)(1.8 nm)/Ag (2.2 nm or about 20 mg/m2)/ZnSnOx (10
nm).
[0071] The coated sample was subjected to a tempering process
(670.degree. C. during 10 minutes).
[0072] The bactericidal properties of the sample were analysed in
accordance with standard JIS Z 2801. A log 2.63 was obtained. This
indicates that good bactericide properties were obtained
simultaneously with tempering characteristics. This suggests that a
certain amount of silver migrated during the tempering step in the
topcoat and that the NiCr layer played a barrier function for the
migration of Ag toward the substrate.
EXAMPLE 7
[0073] Samples of steel were coated with a silver layer using the
vacuum deposition method as in example 1. A first sample was a
galvanized steel of the commercial type "ST37" with a thickness of
1.5 mm. The second one was a sample of steel laminated under cold
condition and without oil of a thickness of 0.2 mm.
[0074] After having been washed properly, the samples were coated
using a silver metal target in an atmosphere of argon. The quantity
of silver deposited was 100 mg/m2 of the surface treated.
[0075] The samples were subjected to a thermal diffusion process at
320.degree. C. during 10 min.
[0076] The bactericidal properties of both samples were analysed as
previously and a log 3.53 was obtained for both samples.
[0077] When the substrate is a metal, particularly a sheet metal,
and particularly steel, a coating layer may be provided at the
surface to receive or contain the antimicrobial agent. Coating
layers selected from one or more of a titanium oxide, a titanium
nitride and a zirconium oxide may be particularly suitable.
[0078] When the substrate is a flat glass substrate, the use of
coating layers selected from one or more of silicon oxide, a
silicon nitride, a tin oxide, a zinc oxide, a zirconium oxide, a
titanium oxide, a titanium nitride and an aluminium nitride may be
used.
[0079] A double coating layer may be used, for example,
substrate/zirconium oxide/titanium oxide.
* * * * *