Translucent glazing comprising at least one pattern that is preferably transparent

Abstract

A glazing, which may be translucent, includes at least one design, which may be transparent. The glazing includes a substrate having two main outer surfaces, at least one of which is a textured surface, made of a dielectric material having a refractive index n1 and at least a part of the textured surface of the substrate is coated with a sol-gel layer made of a dielectric material having a refractive index n2.

Claims

1. A glazing comprising a substrate having two main outer surfaces, at least one of which is a textured surface, consisting of a dielectric material having a refractive index n.sub.1, wherein: at least a part of the textured surface of the substrate is coated with a sol-gel layer consisting of a dielectric material having a refractive index n.sub.2, and the absolute value of the difference in refractive index at 589 nm between constituent dielectric materials of the substrate and the sol-gel layer is less than or equal to 0.020, and wherein the part of the textured surface of the substrate comprising the sol-gel layer has a transmission haze of less than 5% and a lightness of greater than 93%.

2. The glazing as claimed in claim 1, wherein the substrate has two main outer surfaces, at least one of which is a textured surface and the other is a smooth surface.

3. The glazing as claimed in claim 1, wherein the textured surface of the substrate has a roughness parameter Ra of at least 0.5 μm.

4. The glazing as claimed in claim 1, wherein the part of the textured surface of the substrate comprising a sol-gel layer defines a transparent design.

5. The glazing as claimed in claim 1, wherein the thickness of the sol-gel layer is greater than or equal to the peak-to-valley height of the textured surface of the substrate.

6. The glazing as claimed in claim 1, wherein the textured surface of the substrate coated with a sol-gel layer has a roughness parameter Ra of less than 0.1 μm.

7. The glazing as claimed in claim 1, wherein the sol-gel layer comprises a silica-based organic/inorganic hybrid matrix.

8. The glazing as claimed in claim 6, wherein the sol-gel layer also comprises particles of at least one metal oxide or of at least one chalcogenide.

9. The glazing as claimed in claim 7, wherein the silica-based organic/inorganic hybrid matrix also comprises at least one metal oxide.

10. The glazing as claimed in claim 8, wherein the metal oxide comprises a metal chosen from titanium, zirconium, zinc, niobium, aluminum and molybdenum.

11. The glazing as claimed in claim 1, wherein the sol-gel layer comprises an organic/inorganic hybrid matrix of silica and of zirconium oxide in which are dispersed titanium dioxide particles.

12. The glazing as claimed in claim 1, wherein the part of the textured surface of the substrate not comprising a sol-gel layer has a transmission haze of greater than 15% and/or a lightness of less than 90%.

13. The glazing as claimed in claim 1, wherein the substrate is a glass or vitroceramic substrate.

14. A process for manufacturing a glazing as claimed in claim 1, comprising: providing a substrate comprising a textured surface of refractive index n.sub.1, depositing on at least a part of the textured surface of the substrate a sol-gel layer consisting of a dielectric material having a refractive index n.sub.2, for which the absolute value of the difference in refractive index at 589 nm between constituent dielectric materials of the substrate and of the sol-gel layer is less than or equal to 0.020.

15. The process as claimed in claim 14, wherein the absolute value of the difference in refractive index at 589 nm is less than or equal to 0.015.

16. The glazing as claimed in claim 1, wherein the substrate is a polymer substrate.

17. The glazing as claimed in claim 1, wherein the sol-gel layer is based on hydrolysis and condensation of at least one organosilane of general formula R.sub.nSiX.sub.(4-n) in which: n is equal to 1, 2, 3, groups X, which are identical or different, represent hydrolyzable groups selected from the group consisting of alkoxy, acyloxy and halide groups, and groups R, which are identical or different, represent non-hydrolyzable organic groups bonded to silicon via a carbon atom.

Description

(1) The characteristics and advantages of the invention will emerge in the description that follows of several embodiments of a layered element, given solely as an example and made with reference to the attached drawings in which:

(2) FIGS. 1 and 2 are schematic cross sections of a glazing according to the invention;

(3) FIG. 3 shows the change in refractive index as a function of the volume proportions of TiO.sub.2 in a sol-gel layer,

(4) FIG. 4 shows images taken with a scanning electron microscope of satin-finished substrates of transparent rough glass Satinovo® onto which a sol-gel layer has been deposited via a sol-gel process,

(5) FIGS. 5 and 6 are graphs showing the change in haze (right-hand y-axis) and in lightness (left-hand y-axis) as a function of the refractive index of the sol-gel layer and of the variation in refractive index between a substrate Satinovo® and the sol-gel layer.

(6) For the sake of clarity of drawing, the relative thicknesses of the various layers in the figures have not been rigorously respected.

(7) The glazing 1 illustrated in FIG. 1 comprises a substrate 2 and a sol-gel layer 4, which consist of transparent dielectric materials having substantially the same refractive index n2, n4. Each of these elements has a smooth main surface, 2A or 4A, respectively. The textured surface of the substrate is formed by a plurality of designs that are hollowed or protruding relative to a general plane of the surface.

(8) The glazing 1 illustrated in FIG. 2 comprises a sol-gel layer 4 which smoothes out the roughness of the substrate 2. The outer smooth surfaces 2A and 4A of the glazing 1 allow specular transmission of radiation, i.e. the entry of radiation or the exit of radiation without modifying the direction of the radiation.

(9) An example of a process for manufacturing the glazing of the invention is described below. The process for manufacturing a glazing according to the invention may comprise the steps in which: the refractive index of the substrate is measured, and a sol-gel solution is chosen which will give after crosslinking a sol-gel layer for which the absolute value of the difference in refractive index at 589 nm between the constituent dielectric materials of the substrate and of the sol-gel layer is less than or equal to 0.020 and preferably less than or equal to 0.015.

(10) A textured glass substrate of the type such as Satinovo®, Albarino® or Masterglass® or a substrate based on a rigid or flexible polymer material, for example of the type such as polymethyl methacrylate or polycarbonate, may be used. The sol-gel layer is then deposited on the textured surface of the substrate. This layer, in the viscous, liquid or pasty state, embraces the texture of the surface of the substrate.

(11) The glazing according to the invention may be used for all known applications of glazings, such as for vehicles, buildings, street furniture, interior furniture, lighting, etc. The glazing of the invention is most particularly useful as doors, partitions of interior walls, glass shower screens, balconies, furniture, glass shelves, kitchen accessories and work surfaces, etc.

EXAMPLES

I. Preparation of Sol-Gel Solutions and of Sol-Gel Layers Comprising an Adjustable Refractive Index

(12) The sol-gel layers prepared in the examples comprise an organic/inorganic hybrid matrix of silica and of zirconium oxide in which are dispersed titanium dioxide particles. The main compounds used in the sol-gel solutions are: 3-glycidoxypropyltrimethoxysilane (GLYMO), zirconium propoxide in the form of a solution at 70% by mass in propanol, TiO.sub.2, sold under the name Cristal Activ™, in the form of particles with a diameter of less than 50 nm in an aqueous dispersion with a solids content of 23% by mass.

(13) A first precursor composition of the matrix is prepared by mixing the organosilane, the solution of zirconium propoxide, acetic acid and optionally water. The constituents are mixed dropwise with vigorous stirring. The other compounds are then added to this first composition, i.e. the aqueous dispersion of titanium dioxide in the form of particles, the surfactant and optionally other dilution solvents such as ethanol. The sol-gel solution is thus obtained.

(14) Depending on the dispersion proportions of titanium dioxide added to the sol-gel solution, the matrix of the sol-gel layer once crosslinked will be more or less charged with TiO.sub.2 particles. The refractive index of the sol-gel layer depends on the volume fraction of titanium dioxide. It is thus possible to vary the refractive index of the resulting sol-gel layer between 1.490 and 1.670 with a high-precision adjustment of the order of 0.001. It is thus possible to obtain for all types of standard glass substrates used as lower outer layer an index harmony of less than 0.015.

(15) The solids content of the sol-gel layer has an influence on the maximum thickness that it is possible to deposit in one pass.

(16) In order to illustrate these results, various sol-gel solutions were prepared. These solutions were then applied by spraying onto a support and crosslinked for a time of 20 minutes to a few hours at a temperature of 150° C. or 200° C. so as to form sol-gel layers having refractive indices varying between 1.493 to 1.670.

II. Influence of the Volume Proportions of TiO2 on the Refractive Index of the Sol-Gel Layer

(17) The tables below summarize the compositions of the sol-gel solutions tested and also the compositions of the resulting sol-gel layers.

(18) As regards the sol-gel solution, the given proportions correspond to the mass proportions relative to the total mass of the sol-gel solution.

(19) TABLE-US-00001 Sol-gel solution A B C D E F G H I Main com- pounds: GLYMO 68.1 64.2 55.6 52.5 22.5 20.3 18.3 16.6 14.8 Zirconium 4.8 4.5 3.9 3.7 1.6 1.4 1.3 1.2 1.0 propoxide TiO.sub.2 0.0 2.8 4.2 6.5 3.5 5.1 6.6 7.8 9.1 Additives Acetic acid 4.3 4.0 3.5 3.3 1.4 1.3 1.1 1.0 0.9 3M-FC 0.0 0.1 0.2 0.3 0.2 0.2 0.3 0.3 0.4 4430 Solvents Propanol 2.0 1.9 1.7 1.6 0.7 0.6 0.5 0.5 0.4 Water 12.8 21.6 24.4 31.6 16.0 20.9 25.5 29.2 33.3 Ethanol 0.0 12.4 18.2 28.2 15.3 22.2 28.6 33.9 39.6 Total 100 100 100 100 100 100 100 100 100

(20) As regards the sol-gel layer, the volume proportions of TiO.sub.2 are defined relative to the total volume of the main components comprising the hybrid matrix of silica and of zirconium oxide and the TiO.sub.2 particles. The proportions of the main components correspond to the mass proportions of the main compounds of the sol-gel layer relative to the total mass of main compounds.

(21) TABLE-US-00002 Sol-gel layer A B C D E F G H I Main compounds*: Gly-SiO2 96 91 87 82 79 72 65 59 53 ZrO2 4 3 3 3 3 3 2 2 2 TiO2 0 6 9 14 18 26 33 39 46 Volume % of TiO2 0 3 5 8 9.8 15 20.1 24.7 30 Measured index 1.493 1.517 1.529 1.557 1.567 1.600 1.623 1.651 1.674 Theoretical index 1.493 1.515 1.528 1.549 1.564 1.599 — — —

(22) Following the crosslinking of the organosilane and of the zirconium propoxide by hydrolysis reaction and condensation, a matrix is obtained in the sol-gel layer, this matrix being based on silicon oxide comprising a non-hydrolyzable organic group referred to hereinbelow as “Gly-SiO.sub.2” and of zirconium oxide in which are dispersed the TiO.sub.2 particles. These three compounds represent the main compounds of the sol-gel layer.

(23) The volume fraction of titanium dioxide has a linear influence on the refractive index of the sol-gel layer for volume proportions of TiO.sub.2 of less than 20%. For higher proportions, the refractive index continues to increase, but a fall in the slope of the curve is observed. However, once this curve has been determined, a person skilled in the art is capable of estimating, by approximation, the refractive index of a sol-gel layer comprising a volume fraction of TiO.sub.2 of greater than 20%.

(24) FIG. 3 shows the change in refractive index as a function of the volume proportions of TiO.sub.2 in the sol-gel layer. The linear change in refractive index as a function of the proportions of TiO.sub.2 is observed for proportions of less than 20%.

(25) The precision on the refractive index is 7×10.sup.−4 for an error of 0.1% by volume on the amount of TiO.sub.2.

III. SEM Observation

(26) Observations by scanning electron microscopy were performed to ensure that the sol-gel layers make it possible to fill in thickness the roughness of the substrate and to obtain a flat upper surface. The images in FIG. 4 show satin-finish substrates of transparent rough glass Satinovo® from the company Saint-Gobain on which a sol-gel layer O has been deposited via a sol-gel process. The glazing of the invention corresponds to a glass that is rough in places, having transparent and translucent zones.

(27) These substrates 4 mm thick comprise a main textured surface obtained by acid attack. The mean height of the texturing designs of the substrate which corresponds to the roughness Ra of the textured surface of the glass Satinovo® is between 1 and 5 μm. Its refractive index is 1.518 and its peak-to-valley height (PV) is between 12 and 17 μm.

(28) In the left image showing in cutaway view the substrate Satinovo® covered with the sol-gel layer, it is clearly seen that the texture is formed by a plurality of designs that are hollowed or protruding relative to the general plane of the contact surface. The thickness of the sol-gel layer is 14.3 μm.

(29) The right image shows a top view of the same substrate. The sol-gel layer has not been applied to the entire surface of the substrate Satinovo®. The sol-gel layer makes it possible to even out the roughness of the substrate.

(30) This substrate Satinovo® coated with a sol-gel layer has a light transmission TL of 90.1%, a haze of 1.88% and a lightness of 92.5%.

IV. Evaluation of the Influence of the Index Harmony

(31) In order to measure the influence of the index harmony between the sol-gel layer and the substrate, various sol-gel solutions were prepared and deposited onto satin-finish substrates of transparent rough glass Satinovo® defined above. The thicknesses of the sol-gel layers deposited after drying are about 15 μm.

(32) The aim of this test is to show the influence of the index harmony on the optical properties of the glazing, such as: the light transmission values T.sub.L in the visible range as a percentage, measured according to standard ISO 9050:2003 (illuminant D65; 2° observer), the haze transmission values (Haze T) as percentages, measured with a hazemeter according to standard ASTM D 1003 for incident radiation on the layered element on the lower outer layer side, the percentage lightness with the Haze-Gard hazemeter from BYK.

(33) Furthermore, the quality “of vision” through the glazing thus coated was evaluated visually by 5 observers in a blind test, i.e. without the observers knowing the characteristics such as the refractive index or the index harmony of the sol-gel layers with the substrate. The observers attributed for each substrate coated with a sol-gel layer an assessment indicator chosen from: “−” not correct, “+” correct, “++” good, “+++” excellent.

(34) The tables below summarize the compositions of the sol-gel solutions tested and the compositions of the resulting sol-gel layers.

(35) The results obtained are collated in the table below.

(36) TABLE-US-00003 Sol- Index gel 589 TL Haze Lightness Visual observation layer nm Δn (%) (%) (%) P1 P2 P3 P4 P5 G 1.623 −0.105 − − 20.7 − − − − − E 1.566 −0.048 − − 76.9 − − − − − D 1.557 −0.039 − − 87.4 − + ++ ++ ++ P 1.532 −0.014 89.8 0.3 94 + + + ++ ++ C 1.529 −0.010 − − 97.5 ++ ++ ++ ++ ++ O 1.524 −0.006 90.0 0.5 98 +++ +++ +++ +++ +++ B 1.517 0.002 − − 98 +++ +++ +++ +++ +++ N 1.514 0.000 89.8 0.5 100 +++ +++ +++ +++ +++ M 1.508 0.010 90.0 0.5 98 ++ ++ ++ ++ ++ L 1.504 0.014 89.6 0.4 96 ++ ++ ++ ++ ++ K 1.500 0.018 90.0 0.5 93 − + ++ ++ ++ A 1.493 0.025 89.9 1.1 90 − − − − − Q 1.484 0.030 89.5 1.6 78 − − − − − R 1.476 0.038 89.5 3.5 68 − − − − − S 1.468 0.046 89.5 2.9 60 − − − − − Δn represents the variation in index between the substrate Satinovo ® and the sol-gel layer.

(37) FIG. 5 is a graph showing the change in haze (right-hand y-axis) and in lightness (left-hand y-axis) as a function of the refractive index of the sol-gel layer. The vertical black line illustrates the index of the glass substrate Satinovo®.

(38) FIG. 6 is a graph showing the change in the haze (right-hand y-axis) and in the lightness (left-hand y-axis) as a function of the variation in refractive index between the substrate Satinovo® and the sol-gel layer.

(39) When the sol-gel layer has an index of between 1.500 and 1.530, haze values through the substrate thus coated of less than 0.5% are obtained. However, the haze values alone do not suffice to characterize the excellence of vision. This is why the lightness was also determined. It is found that, contrary to the haze values, which are virtually constant in the indicated index range, the lightness values reflect within this range a peak centered for refractive index values of the sol-gel layer about the index value of the substrate, i.e. 1.518. More particularly, good results are obtained for an index difference of less than 0.020 and excellent results are obtained for an index difference of less than 0.015, or even less than 0.005.

(40) In conclusion, the absolute value of the index difference between the substrate of index n.sub.1 and the sol-gel layer of index n.sub.2 is preferably less than 0.020, better still less than 0.015 and even better still less than 0.013 so as to obtain good transparency of the designs.