Optical element comprising a crack-free aerogel

Patent metadata

Field	Value
Publication number	US-9327460-B2
Application number	US-201113994613-A
Country	US
Kind code	B2
Filing date	Dec 14, 2011
Priority date	Dec 16, 2010
Publication date	May 3, 2016
Grant date	May 3, 2016

Abstract

A method manufactures an optical element having a surface that includes cells filled with an aerogel that does not crack during its manufacture or during a subsequent step of impregnating the aerogel with a liquid. The disclosure also relates to the optical elements that can be obtained using the method.

First claim

The invention claimed is:

1. A process for manufacturing a transparent optical element comprising:
a) providing an optical element having a surface with at least one open cell;
b) carrying out a surface treatment of said cell, the surface treatment increasing the wettability of the surface;
c) preparing a solution comprising:
an organic-aqueous solvent;
at least one organic polymer, soluble in said solvent, having a weight-average molecular weight greater than 10,000 g/mol;
at least one alkoxysilane selected from the group consisting of (C 1 to C 3 alkyl)tri(C 1 to C 3 alkoxy)silanes and tetra(C 1 to C 3 alkoxy)silanes and mixtures thereof;

d) adding an acid or base hydrolysis catalyst to the solution so as to obtain a sol;
e) depositing the sol in the pretreated cell before the gel point of the sol is achieved and sealing the filled cell using a film;
f) leaving the optical element to stand in an alcoholic atmosphere for between 15 minutes and 5 hours in order to mature the gel;
g) removing the film sealing the cell in an alcoholic medium;
h) carrying out, in an autoclave, supercritical drying of the gel contained in the cell so as to obtain an aerogel.

2. The process as claimed in claim 1 , wherein the optical element, comprises several open cells on the surface of this optical element, the cells having a largest dimension between 10 and 10,000 μm.

3. The process as claimed in claim 1 , wherein the surface treatment carried out in step b) is performed with a low-pressure oxygen plasma.

4. The process as claimed in claim 1 , wherein the polymer included in the solution is selected from the group consisting of polyvinyl acetate, polyvinyl alcohol, poly(vinyl acetate-co-vinyl alcohol) copolymers; polyoxyethylene, polyoxypropylene and mixtures thereof.

5. The process as claimed in claim 1 , wherein the alkoxysilane included in the solution is tetramethoxysilane.

6. The process as claimed in claim 1 , wherein the sol obtained at the end of step d) comprises:
from 0.5% to 20% by weight, of polyvinyl acetate,
from 20% to 60% by weight of tetramethoxysilane,

the solvent consisting of a water/ethanol mixture.

7. The process as claimed in claim 1 , wherein the sol obtained at the end of step d) also comprises an additive selected from colloidal silica particles and conductive particles.

8. The process as claimed in claim 7 , wherein said conductive particles are selected from indium tin oxide (ITO) particles, tin oxide particles and metal particles.

9. The process as claimed in claim 1 , wherein the drying step h) is carried out with supercritical CO 2 .

10. The process as claimed in claim 1 , further comprising a step i) of, after the supercritical drying step h), purging the autoclave with an anhydrous gas, before removing the optical element.

11. The process as claimed in claim 1 , further comprising a step i) of placing the optical element obtained after step h) into a chamber having a controlled humidity.

12. A process for impregnating the optical element obtained by the process as claimed in claim 1 , comprising impregnating the aerogel contained in the at least one cell of the optical element with a liquid, then sealing the impregnated cell with a sealant that isolates and protects contents of the cell from the external atmosphere.

Assignees

• Biver Claudine
• Cano Jean-Paul
• Courson Rémi
• Calas-Etienne Sylvie
• Etienne Pascal
• Essilor Int
• Ct Nat De La Rech Scientifique—Cnrs

Inventors

• Biver Claudine
• Cano Jean-Paul
• Courson Rémi
• Calas-Etienne Sylvie
• Etienne Pascal

Classifications

• B29D11/00865 Primary

  Applying coatings; tinting; colouring (printing, marking or copying processes B41M; identification in general G09F3/00; producing decorative effects in general B44C; positioning or marking of lenses B24B13/0055) · CPC title

• G02C2202/16

  Laminated or compound lenses · CPC title

• G02C2202/18

  Cellular lens surfaces · CPC title

• G02C7/101

  having an electro-optical light valve (electro-optical elements per se G02F) · CPC title

• G02C7/083

  Electrooptic lenses · CPC title