Transparent substrate with antireflection coating

• US 6,495,203 B2
• Filed: 07/30/2001
• Issued: 12/17/2002
• Est. Priority Date: 02/23/1995
• Status: Expired due to Term

• Current Assignee: Saint-Gobain Vitrage
• Original Assignee: Saint-Gobain Vitrage
• Inventors: Macquart, Philippe, Anderson, Charles-Edward
• Primary Examiner(s): TURNER, ARCHENE A
• Application Number:
  US09/916,346
• Publication Number:
  US 20020001724A1
• Time in Patent Office: 505 Days
• Field of Search: 427/165, 427/166, 427/162, 427/419.1, 427/419.2, 427/419.3, 427/372.2, 204/192.1, 204/192.22, 204/192.26
• US Class Current: 427/166
• CPC Class Codes: B32B 17/10036 comprising two outer glass sheets
• CPC Class Codes: B32B 17/10174 Coatings of a metallic or dielectric material on a constituent layer of glass or polymer
• CPC Class Codes: B32B 17/10201 Dielectric coatings
• CPC Class Codes: B32B 17/10761 containing vinyl acetal
• CPC Class Codes: C03C 17/3417 all coatings being oxide coatings
• CPC Class Codes: C03C 2217/734 comprising an alternation of high and low refractive indexes
• CPC Class Codes: C03C 2218/365 Coating different sides of a glass substrate
• CPC Class Codes: C03C 27/10 with the aid of adhesive specially adapted for that purpose
• CPC Class Codes: Y10T 428/12792 Zn-base component
• CPC Class Codes: Y10T 428/24942 including components having same physical characteristic in differing degree
• CPC Class Codes: Y10T 428/24975 No layer or component greater than 5 mils thick
• CPC Class Codes: Y10T 428/265 1 mil or less
• CPC Class Codes: Y10T 428/31616 Next to polyester [e.g., alkyd]

Abstract

The invention relates to a glass substrate having on at least one of its faces an antireflection coating formed by a stack of thin dielectric material layers having alternately high and low refractive indices. To prevent the modification of the optical properties of the coating in the case where the substrate is subject toga heat treatment such as tempering, bending or annealing, the layer or layers of the stack which are liable to deteriorate on contact with alkali ions such as sodium ions are separated form the substrate by at least one layer forming part of the antireflection coating and forming a “shield” with respect to the diffusion of alkali.

Claims

1. A process for producing a coated glass, the process comprising

depositing a first dielectric material layer on a glass substrate by pyrolysis of dielectric material precursors;

cathodically sputtering a second dielectric material layer on the first dielectric material layer;

forming the coated glass; and

heating the coated glass to a temperature at of least 550°

C., wherein

the coated glass comprises

the glass substrate; and

an antireflection coating on at least one surface of the substrate, where

the coating is a stack of dielectric material layers having alternating high and low refractive indices, and

at least one of the layers is a shield layer which prevents diffusion of alkali metal ions from the substrate through the shield layer.

2. The process according to claim 1, wherein after the heating the coated glass has a light reflection R_L of at most 2% and a blue or blue-green color in reflection, with a variation of R_L of at most 0.3%.

3. The process according to claim 1, wherein the coated glass has variations of a* and b* of at most 2.0 after heating.

4. The process according to claim 1, wherein

the shield layer is a low refractive index dielectric material layer selected from the group consisting of SiO₂, Al₂O₃, Al₂O₃: F and mixtures thereof; and

the coated glass further comprises a high refractive index dielectric material layer between the glass substrate and the shield layer.

5. The process according to claim 1, wherein

the shield layer is a high refractive index dielectric material layer;

and

the shield layer has an optical thickness of 25 nm to 60 nm.

6. The process according to claim 1, wherein the high refractive index dielectric material layer and the shield layer is selected from the group consisting of tin oxide, doped tin oxide, zinc oxide, tantalum oxide and zirconium oxide.

7. The process according to claim 1, wherein

the antireflection coating comprises, in order outward from the glass substrate,

a high refractive index layer directly on the glass substrate;

a first low refractive index layer, serving as the shield layer, including SiO₂ or a mixture of SiO₂ and Al₂O₃;

a layer including Nb₂O⁵; and

a second low refractive index layer including SiO₂ or a mixture of SiO₂ and Al₂O₃.