SUBSTRATE WITH ANTIMICROBIAL PROPERTIES
A process for the production of a substrate having antimicrobial properties is described. It comprises a step consisting of the déposition of a métal non-gelling layer comprising an inorganic antimicrobial agent, starting from a precursor, in métal, 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.
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° C.
2 . Process according to claim 1 , characterised in that the temperature of the thermal treatment is
(i) lower than 450° C.,
(ii) lower than 380° C., or
(iii) lower than 350° C.
3 . (canceled)
4 . Process according to claim 1 , characterised in that the temperature of the thermal treatment is
(i) higher than 200° C.,
(ii) higher than 220° C., or
(iii) higher than 240° 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° and 350° 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 2 ,
(ii) more than 10 mg/m 2 , or
(iii) more than 20 mg/m 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 2 and a second layer based on TiO 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° 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 2 ,
(ii) more than 1 mg/m 2 , or
(iii) more than 10 mg/m 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° C.), 500 hours of UV irradiation (4 340A ATLAS lamps, chamber at 60° C.), after 24 hours immersed in a solution of H 2 SO 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.