Transparent element with diffuse reflection comprising a sol-gel layer

Patent metadata

Field	Value
Publication number	US-9846265-B2
Application number	US-201314414335-A
Country	US
Kind code	B2
Filing date	Jul 11, 2013
Priority date	Jul 13, 2012
Publication date	Dec 19, 2017
Grant date	Dec 19, 2017

Abstract

A transparent layered element with diffuse reflection properties includes two outer layers made of dielectric materials having substantially the same refractive index and a central layer intercalated between the two outer layers, formed either from a single layer which is a dielectric layer with a refractive index different from that of the outer layers or a metallic layer, or from a stack of layers which includes at least one dielectric layer with a refractive index different from that of the outer layers or a metallic layer. The upper outer layer is a sol-gel layer including a silica-based organic/inorganic hybrid matrix.

First claim

The invention claimed is:

1. A transparent layered element having two main smooth outer surfaces, the transparent layered element comprising:
a lower outer layer and an upper outer layer, which each form one of the two main outer surfaces of the transparent layered element and which consist of dielectric materials having substantially the same refractive index, and
a central layer intercalated between the lower outer and upper outer layers, the central layer being formed either (a) by a single layer which is a dielectric layer of refractive index different from that of the lower outer and upper outer layers or a metallic layer, or (b) by a stack of layers which comprises at least one dielectric layer with a refractive index different from that of the lower outer and upper outer layers or a metallic layer,
wherein each contact surface between two adjacent layers of the transparent layered element, one of which is a dielectric layer and the other is a metallic layer or which are both dielectric layers with different refractive indices, is textured and parallel to other textured contact surfaces between two adjacent layers, one of which is a dielectric layer and the other is a metallic layer or which are both dielectric layers with different refractive indices,
wherein the upper outer layer is a sol-gel layer comprising an organic/inorganic hybrid matrix based on silica,
wherein a smooth surface has a roughness parameter corresponding to an arithmetic mean difference Ra of less than 0.10 μm and a textured surface has a roughness parameter corresponding to the arithmetic mean difference Ra of at least 0.5 μm,
wherein the absolute value of the difference in refractive index at 589 nm between constituent dielectric materials of the lower outer and upper outer layers of the transparent layered element is less than or equal to 0.020, and
wherein the transmission haze of the transparent layered element is less than 5% and the lightness of the transparent layered element is greater than 93%.

2. The transparent layered element as claimed in claim 1 , wherein the absolute value of the difference in refractive index at 589 nm between the lower outer and upper outer layers and at least one dielectric layer of the central layer is greater than or equal to 0.3.

3. The transparent layered element as claimed in claim 1 , wherein the sol-gel layer also comprises particles of at least one metal oxide or of at least one chalcogenide.

4. The transparent layered element as claimed in claim 1 , wherein the silica-based organic/inorganic hybrid matrix also comprises at least one metal oxide.

5. The transparent layered element as claimed in claim 3 , wherein the metal oxide comprises a metal chosen from titanium, zirconium, zinc, niobium, aluminum and molybdenum.

6. The transparent layered element 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.

7. The transparent layered element as claimed in claim 1 , wherein the sol-gel layer is obtained by curing a sol-gel solution and comprises the product resulting from the hydrolysis and condensation of at least one organosilane of general formula R n SiX (4-n) in which:
n is equal to 1, 2, 3,
the groups X, which are identical or different, represent hydrolyzable groups chosen from alkoxy, acyloxy or halide groups, and
the groups R, which are identical or different, represent non-hydrolyzable organic groups bonded to silicon via a carbon atom.

8. The transparent layered element as claimed in claim 1 , wherein the sol-gel layer is obtained by curing a sol-gel solution and comprises the product resulting from the hydrolysis and condensation of:
i) at least one organosilane and
ii) at least one precursor of a metal oxide or
iii) particles of at least one metal oxide or of at least one chalcogenide, or both ii) at least one precursor of a metal oxide and iii) particles of at least one metal oxide or of at least one chalcogenide.

9. The transparent layered element as claimed in claim 1 , further comprising at least one additional layer positioned above or below the upper and/or lower outer layers, chosen from:
transparent substrates chosen from polymers, glasses and ceramics comprising two smooth main surfaces,
curable materials that are initially in a viscous, liquid or pasty state suitable for forming operations,
inserts made of thermoformable or pressure-sensitive plastic material.

10. The transparent layered element as claimed in claim 1 , wherein the lower outer layer of the layered element is chosen from:
transparent substrates, one of the main surfaces of which is textured and the other smooth,
a layer of dielectric material chosen from the oxides, nitrides or halides of one or more transition metals, non-metals or alkaline-earth metals,
a layer based on curable materials that are initially in a viscous, liquid or pasty state, suited to forming operations comprising:
photocrosslinkable and/or photopolymerizable materials,
layers deposited via a sol-gel process,

inserts made of thermoformable or pressure-sensitive plastic material.

11. The transparent layered element as claimed in claim 1 , wherein the single layer or the stack of layers of the central layer comprises:
at least one thin layer consisting of a dielectric material chosen from the oxides, nitrides or halides of one or more transition metals, non-metals or alkaline-earth metals,
at least one thin metallic layer, especially a thin layer of silver, gold, copper, titanium, niobium, silicon, aluminum, nickel-chromium (NiCr) alloy, stainless steel, or an alloy thereof.

12. A process for manufacturing a transparent layered element as defined according to claim 1 , comprising:
providing a transparent substrate, one of the main surfaces of which is textured and the other main surface is smooth, as lower outer layer;
depositing a central layer on a main textured surface of the lower outer layer, said depositing comprising, (a) when the central layer is formed by a single layer, which is a dielectric layer with a refractive index different from that of the lower outer layer or a metallic layer, depositing the central layer in compliant manner onto said main textured surface, or (b) when the central layer is formed by a stack of layers comprising at least one dielectric layer with a refractive index different from that of the lower outer layer or a metallic layer, depositing the layers of the central layer successively in compliant manner onto said main textured surface, and
forming the upper outer sol-gel layer on the main textured surface of the central layer opposite the lower outer layer, where the lower and upper outer layers consist of dielectric materials having substantially the same refractive index, by deposition via a sol-gel process.

13. A method comprising utilizing a layered element as claimed in claim 1 , as all or part of glazing for a vehicle, for a building, for street furniture, for interior furniture, for a display screen or for a head-up display system.

14. The transparent layered element as claimed in claim 1 , wherein the absolute value of the difference is less than or equal to 0.015.

15. The transparent layered element as claimed in claim 2 , wherein the absolute value of the difference is greater than or equal to 0.5.

16. The transparent layered element as claimed in claim 7 , wherein n is equal to 1 or 2.

17. The transparent layered element as claimed in claim 16 , wherein n is equal to 1.

18. The trans

Assignees

• Saint Gobain

Inventors

• Ehrensperger Marie-Virginie
• Guillemot François

Classifications

• G02B5/0236

  the diffusion taking place within the volume of the element · CPC title

• G02B27/0101

  characterised by optical features (G02B27/0172 takes precedence) · CPC title

• G02B1/04

  made of organic materials, e.g. plastics (G02B1/08 takes precedence) · CPC title

• B32B17/10587

  created by embossing · CPC title

• G02B2027/0194

  with combiner of laminated type, for optical or mechanical aspects · CPC title