High transmittance, low emissivity coatings for substrates

• US 5,302,449 A
• Filed: 03/27/1992
• Issued: 04/12/1994
• Est. Priority Date: 03/27/1992
• Status: Expired due to Term

• Current Assignee: Cardinal CG Company (Cardinal Glass Industries Incorporated)
• Original Assignee: Cardinal IG Company (Cardinal Glass Industries Incorporated)
• Inventors: Bond, Robert, Eby, Eric, O'Shaughnessy, Roger
• Primary Examiner(s): TURNER, ARCHENE A
• Application Number:
  US07/859,576
• Time in Patent Office: 746 Days
• Field of Search: 428/472, 428/432, 428/433, 428/336, 428/216, 428/697, 428/701, 428/702, 359/359
• US Class Current: 428/336
• 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 a light. The coating employs a base coat adjacent to the transparent substrate having a thickness of no more than about 275 Angstroms 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 outer most 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 substrate having a coating on a surface 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 applied to a surface of said substrate at a thickness of no more than about 275 Angstroms;

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

(c) An intermediate layer of an anti reflective metal oxide applied over said first reflective metal layer;

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

(e) An outer anti-reflective layer of a metal oxide carried over said second reflective metal layer.

2. The coated substrate of claim 1 wherein the ratio of the thickness of the base coat to the thickness of the intermediate anti-reflective layer is no more than about 0.33.

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

4. A high transmittance, low emissivity coated substrate comprising a substrate having a coating on a surface providing the coated substrate with a substantially neutral color, the coating comprising:

(a) a base coat of an anti-reflective metal oxide applied to a surface of said substrate at a thickness of no more than about 275 Å

;

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

(c) an antireflective layer of a metal oxide carried over said reflective metal layer; and

(d) an abrasion-resistant overcoat as the 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 thereof applied at a thickness which does not substantially affect the optical properties of said coating.

5. The coated substrate of claim 4 wherein the overcoat is an oxide of a metal selected from the group consisting of zinc, tin, indium and bismuth.

6. The coated substrate of claim 4 wherein the overcoat is formed of zinc oxide.

7. The coated substrate of claim 6 wherein the zinc oxide is applied at a thickness of between about 5 Å

and about 20 Å

.

8. The coated substrate of claim 4 wherein the metal oxide of the overcoat is applied at an optical thickness of between about 10 Å

and about 40 Å

.

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

(a) A base coated of an anti-reflective metal oxide applied to a surface of said substrate at a thickness of no more than about 275 Angstroms;

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

(c) An intermediate layer of an anti-reflective metal oxide applied over said first reflective metal layer;

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

(e) An outer anti-reflective layer of a metal oxide carried over said second reflective metal layer,

the total thickness of the coating being no more than about 1600 Angstroms.

10. The coated substrate of claim 9 wherein the total thickness is between about 1500 Angstroms and 1600 Angstroms.