High transmittance, low emissivity coatings for substrates

• US 6,838,159 B2
• Filed: 01/09/2003
• Issued: 01/04/2005
• Est. Priority Date: 03/27/1992
• Status: Expired due to Fees

• Current Assignee: Cardinal CG Company (Cardinal Glass Industries Incorporated)
• Original Assignee: Cardinal Glass Industries Incorporated
• Inventors: Bond, Robert, Eby, Eric, O'Shaughnessy, Roger
• Primary Examiner(s): Turner, Archene
• Application Number:
  US10/339,519
• Publication Number:
  US 20030104220A1
• Time in Patent Office: 726 Days
• Field of Search: 428/216, 428/336, 428/433, 428/472, 428/701, 428/702, 428/697, 359/359
• US Class Current: 428/216
• CPC Class Codes: B32B 17/06 comprising glass as the main or only constituent of a layer, next to another layer of a specific material
• CPC Class Codes: C03C 17/36 at least one coating being a metal
• CPC Class Codes: C03C 17/3618 Coatings of type glass/inorganic compound/other inorganic layers, at least one layer being metallic
• CPC Class Codes: C03C 17/3639 Multilayers containing at least two functional metal layers
• CPC Class Codes: C03C 17/3642 the multilayer coating containing a metal layer
• CPC Class Codes: C03C 17/3644 the metal being silver
• CPC Class Codes: C03C 17/366 Low-emissivity or solar control coatings
• CPC Class Codes: C03C 17/3681 the multilayer coating being used in glazing, e.g. windows or windscreens
• CPC Class Codes: C03C 2217/78 Coatings specially designed to be durable, e.g. scratch-resistant
• CPC Class Codes: C23C 14/086 of zinc, germanium, cadmium, indium, tin, thallium or bismuth
• CPC Class Codes: C23C 14/185 by cathodic sputtering
• CPC Class Codes: G02B 1/115 Multilayers
• CPC Class Codes: G02B 5/08 Mirrors vehicle mirrors involving special optical features B60R1/08
• CPC Class Codes: G02B 5/205 Neutral density filters
• CPC Class Codes: G02B 5/26 Reflecting filters G02B5/28 takes precedence
• 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

Abstract

The present invention provides a coating for a transparent substrate which exhibits a “neutral” color through a wide range of angles of incidence of light. The coating employs a base coat adjacent the transparent substrate having a thickness of no more than about 275 Å and may include two reflective metal layers having an intermediate layer of an anti-reflective metal oxide therebetween and an outer anti-reflective layer of metal oxide over the second reflective metal layer. If so desired, the coating of the invention may include an abrasive-resistant overcoat as its outermost layer. This overcoat is desirably formed of an abrasive-resistant metal oxide, such as zinc oxide applied at a thickness which does not significantly affect the optical properties of said coated substrate.

Claims

1. A high transmittance, low emissivity coated substrate comprising a coating providing the coated substrate with a substantially neutral color over a wide range of angles of incidence, the coating comprising:

(a) a base coat of an anti-reflective metal oxide having a refractive index of about 2.0 or more applied to a surface of said substrate at an optical thickness of no more than about 550 Å

;

(b) a first reflective metal layer applied over said base coat;

(c) an intermediate anti-reflective layer applied over said first reflective metal layer, the ratio of thickness of the base coat to the thickness of the intermediate layer being no more than about 0.33;

(d) a second reflective metal layer applied over said intermediate anti-reflective layer; and

(e) an outer anti-reflective layer applied over said second reflective metal layer;

wherein the coating has a total thickness of about 1700 Å

or less.

2. The coated substrate of claim 1 further comprising an abrasion-resistant overcoat as an outermost layer of the coating, the overcoat being formed of a material having greater mechanical durability than the immediately underlying layer.

3. The coated substrate of claim 1 further comprising an abrasion-resistant overcoat as an outermost layer of the coating, the overcoat being formed of an oxide of a metal selected from the group consisting of zinc, tin, indium, bismuth and combinations thereof.

4. The coated substrate of claim 1 wherein the coated substrate retains the substantially neutral color at angles of incidence of up to about 45°

.

5. The coated substrate of claim 1 wherein the basecoat has an optical thickness of about 300 Å

to 550 Å

.

6. The coated substrate of claim 1 wherein the total thickness of the coatings is about 1600 Å

or less.

7. The coated substrate of claim 6 wherein the total thickness of the coating is between about 1500-1600 Å

.

11. The coated substrate of claim 7 wherein the metal oxide of the overcoat is applied at an optical thickness of between about 10 Å

and about 40 Å

.

12. The coated substrate of claim 7 wherein the coated substrate retains the substantially neutral color at angles of incidence of up to about 45°

.

13. The coated substrate of claim 7 wherein the base coat has an optical thickness of about 300 Å

to 550 Å

.

14. The coated substrate of claim 7 wherein the total thickness of the coating is about 1600 Å

or less.

15. The coated substrate of claim 7 wherein the total thickness of the coating is between 1500 Å

and 1600 Å

.

8. A high transmittance, low emissivity coated substrate comprising a coating providing the coated substrate with a substantially neutral color, the coating comprising:

(a) a base coat of an anti-reflective metal oxide having a refractive index of about 2.0 or more applied to a surface of said substrate at an optical thickness of no more than about 550 Å

;

(b) a reflective metal layer applied over said base coat;

(c) an anti-reflective layer applied over the reflective metal layer, the ratio of the thickness of the base coat to the thickness of the anti-reflective layer being no more than about 0.33; and

(d) an abrasion-resistant overcoat as outermost layer of the coating, the overcoat being formed of an oxide of a metal selected from the group consisting of zinc, tin, indium, bismuth and alloys including such metals, the overcoat being applied at a thickness which does not substantially affect the optical properties of the coating;

wherein the coating has a total thickness about 1700 Å

or less.

9. The coated substrate of claim 8 wherein the overcoat is formed of zinc oxide.

10. The coated substrate of claim 8 wherein the zinc oxide is applied at a thickness of between about 5 Å

and about 20 Å

.

16. A high transmittance, low emissivity coated substrate comprising a glass pane bearing a coating providing the coated substrate with a substantially neutral color over a wide range of angles of incidence, the coating comprising:

(a) a base coat of an anti-reflective metal oxide having a refractive index of about 2.0 or more applied to a surface of said substrate at an optical thickness of no more than about 550 Å

;

(b) a first reflective metal layer applied over said base coat;

(c) an intermediate anti-reflective layer applied over said first reflective metal layer, the ratio of the thickness of the base coat to the thickness of the intermediate anti-reflective layer no more than about 0.33;

(d) a second reflective metal layer applied over said intermediate anti-reflective layer; and

(e) an outer anti-reflective layer applied over said second reflective metal layer;

wherein the coating is about 1700 Å

or less.

17. The coated substrate of claim 16 wherein the coated substrate retains the substantially neutral color at angles of incidence of up to about 45°

.

18. The coated substrate of claim 16 wherein the base coat has an optical thickness of about 300 Å

to 550 Å

.

19. The coated substrate of claim 16 wherein the total thickness of the coating is about 1600 Å

or less.

20. A high transmittance, low emissivity coated substrate comprising a coating providing the coated substrate with a substantially neutral color over a wide range of angles of incidence, the coating comprising:

(a) a base coat of an anti-reflective metal oxide having a refractive index of about 2.0 or more applied to a surface of said substrate at an optical thickness of about 300 Å

to 550 Å

;

(b) a first reflective metal layer applied over said basecoat;

(c) an intermediate anti-reflective layer applied over said first reflective metal layer the ratio of thickness of the base coat to the thickness of the intermediate layer being no more than about 0.33;

(d) a second reflective metal layer applied over said intermediate anti-reflective layer; and

(e) an outer anti-reflective layer applied over said second reflective metal layer;

wherein the coating has a total thickness of about 1700 Å

or less.