# US 7,745,009 B2 · Low-emissivity glazing

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- Number: US 7,745,009 B2
- Document ID: US7745009B2
- Status: Granted
- Kind: B2
- Application number: 11/908,666
- Filed: 2006-03-16
- Published: 2009-01-01
- Granted: 2010-06-29
- Earliest claimed: 2005-03-17
- Assignees: Agc Glass Europe
- Inventors: Daniel Decroupet; Jean-Michel Depauw
- Web page: https://patentgrep.com/patent/US7745009B2

## CPC

- C03C 17/3644: {the metal being silver}
- C03C 17/36: at least one coating being a metal
- C03C 17/3652: {the coating stack containing at least one sacrificial layer to protect the metal from oxidation}
- C03C 17/366: {Low-emissivity or solar control coatings}
- Y10T 428/24975: No layer or component greater than 5 mils thick
- Y10T 428/265: 1 mil or less
- Y10T 428/266: of base or substrate
- C03C: CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

Low emissivity glazing which is an assembly of thin layers including at least one metal layer reflecting infrared rays between one or more dielectric layers located between the metal layer and the glass sheet and on the metal layer, the light transmission of one clear float glass sheet 4 mm thick coated with said layers being not less than 83%, the metal layer being selected such that the emissivity is not higher than 0.042.

## Claims

### Claim 1

A low-emissivity glazing comprising:
a glass sheet; and
an assembly of layers coated on the glass sheet including:
at least one metal layer that reflects infrared rays;
a first sub-assembly of at least three dielectric layers located between the metal layer and the glass sheet, said first sub-assembly including:
a first dielectric layer comprising zinc oxide and located immediately under the metal layer,
a second dielectric layer comprising metal oxide, nitride, or oxynitride having a refractive index greater than 1.9,
a third dielectric layer comprising metal oxide, nitride, or oxynitride having a refractive index greater than 1.9; and
a second sub-assembly of layers on a side of the metal layer opposite the first sub-assembly of layers, said second sub-assembly including:
a fourth dielectric layer,
wherein, when the glass sheet is a clear float glass sheet with a thickness of 4 mm the low emissivity glazing has a visible light transmission at least equal to 83%, and
wherein the emissivity of the coated glass sheet is not greater than 0.042.

### Claim 2 (depends on 1)

The glazing as claimed in claim 1, wherein the emissivity is not greater than 0.038.

### Claim 3 (depends on 1)

The glazing as claimed in claim 1, wherein the emissivity is not greater than 0.035.

### Claim 4 (depends on 1)

The glazing as claimed in claim 1, wherein the metal layer is a silver layer having a thickness at least equal to 12 nm.

### Claim 5 (depends on 4)

The glazing as claimed in claim 4, wherein the thickness of the silver layer is not greater than 18 nm.

### Claim 6 (depends on 5)

The glazing as claimed in claim 5, wherein the thickness of the silver layer is from 12.5 to 16 nm.

### Claim 7 (depends on 4)

The glazing as claimed in claim 4, wherein the optical path of the first sub-assembly of layers is from 50 to 90 nm, and the optical path of the second sub-assembly of layers located above the silver layer is from 70 to 110 nm.

### Claim 8 (depends on 7)

The glazing as claimed in claim 7, wherein the optical path of the first sub-assembly of layers is from 55 to 80 nm, and the optical path of the second sub-assembly of layers is from 75 to 100 nm.

### Claim 9 (depends on 4)

The glazing as claimed in claim 4, wherein the color in reflection, expressed in the CIELab coordinates, is −4<a*≦0.5 and −14<b*≦1.

### Claim 10 (depends on 9)

The glazing as claimed in claim 9, wherein the color in reflection is −3<a*≦0 and −12<b*≦0.

### Claim 11 (depends on 1)

The glazing as claimed in claim 1, wherein the metal layer is a silver layer.

### Claim 12 (depends on 11)

The glazing as claimed in claim 11, wherein the first dielectric layer has a thickness which is not greater than 15 nm.

### Claim 13 (depends on 12)

The glazing as claimed in claim 12, wherein the thickness of the first dielectric layer is between 3 and 8 nm.

### Claim 14 (depends on 1)

The glazing as claimed in claim 1, wherein the metal layer comprises silver, the second sub-assembly of layers further comprising:
a barrier layer superposed directly on the metal layer, said barrier layer formed from a metal oxide or nitride, the metal in said barrier layer being from the group comprising: Ti, Zr, Al, Ni, Fe, Cr, Zn, Nb, Ta, In and mixtures thereof.

### Claim 15 (depends on 14)

The glazing as claimed in claim 14, wherein the thickness of the barrier layer is at most equal to 5 nm.

### Claim 16 (depends on 15)

The glazing as claimed in claim 15, wherein the thickness of the barrier layer is at most equal to 4 nm.

### Claim 17 (depends on 1)

The glazing as claimed in claim 1, wherein the second and third dielectric layers have refractive indices greater than that of the glass sheet, the second dielectric layer is farther from the glass sheet than the third dielectric layer, and the second dielectric layer has a higher refractive index than the third dielectric layer.

### Claim 18 (depends on 17)

The glazing as claimed in claim 17, wherein the metal layer comprises silver, the third dielectric layer has a refractive index between 1.9 and 2.3, and the second dielectric layer comprises titanium oxide and is deposited on the third dielectric layer.

### Claim 19 (depends on 18)

The glazing as claimed in claim 18, wherein the third dielectric layer is deposited on the glass and is made from zirconium, zinc optionally as an alloy with aluminum, or from an alloy based on titanium and on a metal from the group comprising aluminum, tin, zinc, indium, hafnium, antimony and zirconium.

### Claim 20 (depends on 1)

The glazing as claimed in claim 1, wherein the second and third dielectric layers have refractive indices greater than that of the glass sheet, the second dielectric layer located under the first dielectric layer and being an oxide, nitride or oxynitride layer of zirconium or of an alloy based on titanium and on a metal from the group comprising aluminum, tin, zinc, indium, hafnium, antimony and zirconium.

### Claim 21 (depends on 20)

The glazing as claimed in claim 20, wherein the third dielectric layer is in contact with the glass sheet and is a titanium oxide layer.

### Claim 22 (depends on 19)

The glazing as claimed in claim 19, wherein the third dielectric layer has a thickness of 3 to 10 nm.

### Claim 23 (depends on 22)

The glazing as claimed in claim 22, wherein the third dielectric layer has a thickness from 4 to 8 nm.

### Claim 24 (depends on 18)

The glazing as claimed in claim 18 wherein the second dielectric layer has a thickness greater than 12 nm and less than 16 nm.

### Claim 25 (depends on 24)

The glazing as claimed in claim 24, wherein the second dielectric layer has a thickness of 10 to 15 nm.

### Claim 26 (depends on 1)

A glazing comprising:
a first glass sheet coated according to claim 1;
a second glass sheet; and
a space provided between the first and second glass sheets containing an atmosphere composed of at least 85% argon.

### Claim 27 (depends on 26)

The glazing as claimed in claim 26, wherein when the first and second glass sheets are 4 mm thick clear float glass sheets, the visible light transmission is not less than 73%, and preferably is not less than 75%.

### Claim 28 (depends on 26)

The glazing as claimed in claim 26, wherein in reflection, the colorimetric coordinates in the CIELab system are established at: −3<a*<0 and −8<b*<0.

### Claim 29 (depends on 1)

The glazing as claimed in claim 1, wherein the zinc oxide is sub-stoichiometric.

### Claim 30 (depends on 18)

The glazing as claimed in claim 18, wherein the second or third dielectric layer has a refractive index between 2.1 and 2.3.

### Claim 31 (depends on 1)

The glazing as claimed in claim 1, wherein the low emissivity glazing has a visible light transmission of at least 85%.