Title of Invention

A HEAT-RESISTANT LOW-EMISSIVITY MULTILAYER SYSTEM FOR TRANSPARENT SUBSTRATES

Abstract A heat-resistant low-E multilayer system for transparent substrates, in particular for window panes, which has a lower antireflection coating having a high-refringence layer, a wetting layer consisting essentially of ZnO to which a silver-based functional layer is joined, a barrier layer over the functional layer, an upper antireflection coating consisting of a layer or several partial layers and a cover coating consisting of a layer or several partial layers, another metal oxide layer that serves as antiscattering layer being placed in the lower antireflection coating between the high-refringence layer and the wetting layer, characterized in that the antiscattering layer located between the high-refringence layer and the wetting layer is a mixed oxide layer with a thickness of at least 0.5 nm, made of NiCrOx or InSnOx (ITO).
Full Text

LOW-EMISSIVITY (LOW-E) THIN-FILM MULTILAYER COATING
WITH INTERMEDIATE ANTISCATTERING LAYERS
The invention relates to a heat-resistant
low-emissivity multilayer system for transparent
substrates, in particular for windows, which has the
features of the preamble of claim 1.
It comprises a lower antireflection coating having a
highly refringent layer with in particular a TiO2, Nb2O5
or TiNbOx layer and a wetting layer essentially
consisting of ZnO, to which a silver-based functional
layer is joined, with a barrier layer on top of this
silver layer, an upper antireflection coating
consisting of a layer or several partial layers and a
cover coating consisting of a layer or several partial
layers, another metal oxide layer that serves as
antiscattering layer being placed in the lower base
antireflection coating between the high-refringence
layer and the ZnO layer.
Multilayer systems that are suitable for thermal
bending and/or toughening operations carried out on
glass panes, in which the ZnO-based wetting layer is
immediately adjacent a TiO2 layer are disclosed, for
example, by document DE 197 26 966 and document DE 198
50 023. However, it turns out that, after the
toughening operation, the proportion of light scattered
by these multilayer systems is relatively high. As
probable cause, it is assumed in document EP 1 53 8 131
that, during the toughening operation, diffusion
processes via which the TiO2 layer is destroyed take
place on the boundary surface between TiO2 and ZnO. It
may also be hypothesized that, at high temperature,
Zn2TiO4 is formed by diffusion processes on the boundary
surface and that, in the crystalline state, this may be
the cause of the high proportion of scattered light.

To inhibit these diffusion processes, document
EP 1 538 131 proposes to place an SnO2 antiscattering
layer between the high-refringence layer and the ZnO
layer. The high-refringence layer will thus be
protected during the toughening operation, so that the
high refractive index of this layer may be fully used,
even after the toughening operation.
Although a considerable reduction in the proportion of
scattered light is observed when an SnO2 antiscattering
layer is provided, this proportion is however always
quite high. Moreover, the emissivity does not reach the
desired low values.
The invention is based on a heat-resistant multilayer
system that has the fundamental structure mentioned
above. The problem at the basis of the invention is how
to further improve the properties of such a multilayer
system, and in particular to further decrease the
proportion of scattered light after the toughening
operation, to further increase the transmission in the
visible range, to further reduce the surface
resistance, and therefore the emission values, and to
achieve values that are as high as possible within the
infrared radiation range.
According to the invention, this problem is solved with
the features indicated in claim 1.
The heat-resistant low-E multilayer system for
transparent substrates, in particular for window panes,
according to the invention has a lower antireflection
coating having a high-refringence layer, a wetting
layer consisting essentially of ZnO to which a silver-
based functional layer is joined, a barrier layer over
the functional layer, an upper antireflection coating
consisting of a layer or several partial layers and a
cover coating consisting of a layer or several partial
layers, another metal oxide layer that serves as

antiscattering layer being placed in the lower
antireflection coating between the high-refringence
layer and the wetting layer. The antiscattering layer
located between the high-refringence layer and the
wetting layer is a mixed oxide layer with a thickness
of at least 0.5 nm, made of NiCrOx or InSnOx (ITO) .
The term "high-refringence layer" within the context of
the present invention is understood to mean a layer
whose optical index is at least equal to 2.2. This
layer is preferably a non-nitride layer, and in
particular an oxide layer.
Preferred compositions of the multilayer system and the
preferred thickness ranges of the individual layers
will be given in the dependant claims and illustrative
examples that follow.
In particular, the high-refringence layer is,
preferably, made of TiO2, Nb2O5 or TiNbOx.
Moreover, the high-refringence layer is placed directly
on the surface of the glass or a dielectric layer, the
refractive index n of which is smaller - i.e. less than
2.2, while still being preferably greater than 1.8 -
than the refractive index of the high-refringence layer
that follows, is placed between the surface of the
glass and the high-refringence layer, in particular
when the high-refringence layer is made of TiO2, Nb2O5
or TiNbOx. In this case, this dielectric layer placed
between the surface of the glass and the high-
refringence layer preferably consists of SnO2, ZnO, SiO2
or Si3N4.
Preferably, the barrier layer is a metal layer or a
layer of a lightly hydrogenated titanium alloy
consisting of 50 to 80 wt% Ti and 20 to 50 wt% Al.

In one particular variant, the heat-resistant low-E
multilayer system for transparent substrates, in
particular for window panes, according to the invention
has a lower antireflection coating having a high-
refringence layer, a wetting layer consisting
essentially of ZnO to which a silver-based functional
layer is joined, a barrier layer over the functional
layer, an upper antireflection coating consisting of a
layer or several partial layers and a cover coating
consisting of a layer or several partial layers,
another metal oxide layer that serves as antiscattering
layer being placed in the lower antireflection coating
between the high-refringence layer and the wetting
layer, the antiscattering layer located between the
high-refringence layer and the wetting layer being a
mixed oxide layer with a thickness of at least 0.5 nm,
made of NiCrOx or InSnOx (ITO) .
In one advantageous variant, the multilayer system
according to the invention has the following multilayer
structure:
glass/SnO2/TiO2/NiCrOx/ZnO:Al/Zn/Ag/TiAl (TiH,) /ZnO:Al/
Si3N4/ZnSnSbOx/Zn2TiO4.
In another advantageous variant, the multilayer system
according to the invention has the following multilayer
structure:
glass/SnO2/TiO2/ITO/ZnO:Al/Zn/Ag/TiAl (TiH) /ZnO:Al/Si3N4/
ZnSnSbOx/Zn2TiO4.
The invention will be described in greater detail by
means of two illustrative examples that are compared
with two comparative examples of the prior art. Since
the provisions according to the invention optimize
particularly the optical and energy properties, the
evaluation of the quality of the layers is based mainly
on the measurements of the scattered light, the surface
resistance and the emissivity. Consequently, to
evaluate the properties of the layers, the measurements

and tests given below were carried out on coated
windows:
A. Measurement of the thickness (d) of the silver
layer by X-ray fluorescence analysis;
B. Measurement of the scattered light (H) in %
using a scattered light measurement instrument, from
the company Gardner;
C. Measurement of the transmission (T) in % using
a measurement instrument from the company Gardner;
D. Measurement of the electrical surface
resistance (R) in Ω/□ using an FPP 5000 Veeco Instr.
instrument and an SQOHM-1 manual measurement
instrument; and
E. Measurement of the emissivity (En) in % using
an MK2 measurement instrument from the company Sten
Löfring.
After the emissivity is measured, the emissivity values
are calculated using the surface resistance values
through the formula En = 0.0106 x R (see H.-J. Glaser:
"Dünnfilmtechnologie auf Flachglas [Thin-film
technology on flat glass]", Verlag Karl Hofmann 1999,
page 144) and the measured values of En are compared
with the calculated values E*n. The smaller the
difference between the measured values En and the
calculated values E*n, the better the thermal stability
of the multilayer system.
For each of the measurements, specimens measuring
4 0 x 5 0 cm cut from the central part of a' coated window
4 mm in thickness are used. The specimens are heated to
a temperature of 720 to 730°C in a toughening furnace
of the 47067 type from the company EFKO and then
thermally toughened by suddenly cooling them in air.
All the specimens undergo the same thermal stressing in
this way.
It should also be pointed out that the multilayer
system according to the invention achieves its best

values, in terms of thermal insulation, infrared
reflection and light transmission, on windows only
after the heat treatment (toughening) of the substrates
on which said system is deposited. The antiscattering
layer also plays an essential role during the heat
treatments. However, the multilayer system described
here may be used commercially with slight thermal
insulation and light transmission deficiencies even
without having been heat treated, and therefore in
particular on non-toughened windows, on plastic windows
and also on films. The illustrative examples below
however relate to all uses of the multilayer system on
substrates consisting of thermally toughened glass
windows.
Comparative example 1
A low-E multilayer system corresponding to the prior
art (DE 102 35 154 B4) was deposited on float glass
sheets 4 mm in thickness in an industrial continuous
coating plant using the process of reactive magnetron
sputtering, the numbers that follow the chemical
symbols indicating the thickness of each layer in nm:
glass/SnO2 (18)/TiO2(10) /ZnO :Al(6)/Zn(1.5)/Ag(11.6)/
TiAl (TiH) (2)/ZnO:Al (5)/Si3N4(30)/ZnSnSbOx(3)/Zn2TiO4 (2) .
The TiO2 layer is deposited by sputtering from two
tubular targets made of TiOx ceramic in a working gas
consisting of an Ar/O2 mixture, the addition of O2 being
about 3% by volume. The ZnO:Al layers were deposited by
sputtering from a ZnAl metal target containing 2 wt%
Al. The thin Zn metal film was deposited under
unreactive conditions from the same target material.
The barrier layer placed on the silver layer was
deposited by reactive sputtering from a metal target in
an Ar/H2 (90/10 vol%) working gas mixture, the target
containing 64 wt% Ti and 36 wt% Al. During the reactive
sputtering, titanium hydride is formed, the degree of
hydrogenation of which can be defined only with

difficulty. If the bond is stoichiometric, the value of
ℓ is between 1 and 2.
The upper antireflection layer was deposited by
reactive sputtering from an Si target in an Ar/N2
working gas mixture.
The ZnSnSbOx lower cover layer was produced from a
metal target consisting of a ZnSnSb alloy containing
68 wt% Zn, 30 wt% Sn and 2 wt% Sb in an Ar/O2 working
gas and the upper cover layer (top layer) was also
deposited by reactive sputtering from a metal target
consisting of a ZnTi alloy containing 73 wt% Zn and
27 wt% Ti.
The following values were determined on the toughened
coated specimens of this comparative example:

The proportion of scattered light, which is 0.7%,
considerably exceeds the still tolerable limit of 0.5%.
Furthermore, a large difference is found between the
measured value and the calculated value of the
emissivity. Under oblique illumination by a halogen
lamp, a thin (hazy) film is seen.
Comparative example 2
To continue the comparison, the multilayer system of
document EP 1 538 131 as taught in comparative example
1 was provided with an SnO2 antiscattering layer
between the TiO2 layer and the ZnO layer. This
multilayer system therefore had the following
structure:

glass/SnO2(18)/TiO2(10)/SnO2(5)/ZnO:Al(6)/Zn(1.5)/
Ag (11. 6) /TiAl (TiH) (2) /ZnO:Al (5) /Si3N4 (30) /ZnSnSbOx (3) /
Zn2TiO4(2).
The measurements carried out on the specimens thermally
toughened under the same conditions as in comparative
example 1 gave the following values:

Thanks to the arrangement of the SnO2 antiscattering
layer, the proportion of scattered light was
considerably reduced compared with the above
comparative example, but it was still 0.5%. A smaller
difference was also observed between the measured value
and the calculated value of the emissivity. At 3.9%,
the difference was still relatively large, and it had
to be concluded from this that the Ag layer still
underwent considerable degradation during the
toughening operation.
The insertion of the SnO2 layer made the multilayer
system generally more malleable, this being expressed
by a greater scratch sensitivity and a greater tendency
for surface damage during washing operations.
Illustrative example 1
A modified multilayer system according to the invention
was produced on the same coating plant as that used for
comparative examples 1 and 2, the system having the
following structure:

glass/SnO2 (18) /TiO2 (10) /NiCrOx (2 . 5) /ZnO: Al (6) /Zn(l. 5) /
Ag(ll. 6) /TiAl (TiH,) (2) /ZnO:Al (7) /Si3N4 (30) /ZnSnSbOx (3) /
Zn2TiO4(2).
The modification over comparative example 2 lay in the
fact that, instead of an SnO2 layer, an NiCrOx
antiscattering layer was inserted between the TiO2
layer and the ZnO layer. The suboxidized NiCrOx layer
was deposited by sputtering from a flat metal target in
DC mode and in an Ar/O2 atmosphere, the O2 content in
the working gas being about 3 0% by volume.
The specimens were toughened in the same manner as the
specimens of the comparative examples. The measurements
carried out on the toughened coated specimens gave the
following values:

The proportion of scattered light was therefore reduced
to half that of comparative example 2. Likewise, the
difference between the measured emissivity and the
calculated emissivity became considerably smaller,
thereby making it possible to conclude that the
insertion of the NiCrOx layer made the silver layer
considerably more stable during the toughening
operation.
The behavior of the multilayer system in use was
considerably improved, this being expressed by a
substantially lower scratch sensitivity. Even when the
toughening times were extended by 2 0%, no unfavorable
effect was observed. This meant that the temperature

resistance of the multilayer system was further
improved. The multilayer system was optically shiny and
even under oblique illumination using a halogen lamp no
film (light haze) was seen.
Illustrative example 2
A modified multilayer system according to the invention
was produced in the same coating plant as for the
previous examples, this system having the following
structure:
glass/SnO2(18)/TiO2(6)/ITO(2.5)/ZnO:Al(6)/Zn(1.5)/
Ag(11.6) /TiAKTiHℓ) (2) /ZnO :Al (7) /Si3N4 (30) /ZnSnSbOx(3) /
Zn2TiO4(2).
The thin ITO antiscattering layer was deposited by
sputtering from a flat ceramic target in an argon
atmosphere to which no oxygen was added.
After the heating and toughening treatment, which took
place under the same conditions as in the case of the
previous examples, the following values were determined
on the specimens:

Similarly, comparison with comparative example 2 shows
that an ITO antiscattering layer according to the
invention gives better results than an SnO2
antiscattering layer.

WE CLAIM:
1. A heat-resistant low-E multilayer system for transparent
substrates, in particular for window panes, which has a lower
antireflection coating having a high-refringence layer, a wetting
layer consisting essentially of ZnO to which a silver-based
functional layer is joined, a barrier layer over the functional
layer, an upper antireflection coating consisting of a layer or
several partial layers and a cover coating consisting of a layer
or several partial layers, another metal oxide layer that serves
as antiscattering layer being placed in the lower antireflection
coating between the high-refringence layer and the wetting
layer, characterized in that the antiscattering layer located
between the high-refringence layer and the wetting layer is a
mixed oxide layer with a thickness of at least 0.5 nm, made of
NiCrOx or lnSnOx (ITO).
2. The multilayer system as claimed in claim 1, wherein the high-
refringence layer is made of TiO2, Nb2O5 or TiNbOx .
3. The multilayer system as claimed in claim 1 or 2, wherein the
high-refringence layer is placed directly on the surface of the
glass .
4. The multilayer system as claimed in claim 1 or 2, wherein a
dielectric layer, the refractive index n of which is smaller than
the refractive index of the high-refringence layer that follows, is

placed between the surface of the glass and the high-refringence
layer.
5. The multilayer system as claimed in the preceding claim,
wherein the dielectric layer placed between the surface of the
glass and the high-refringence layer consists of SnO2, ZnO,
SiO2 or Si3N4.
6. The multilayer system as claimed in one of the preceding
claims, wherein the barrier layer is a metal layer or a layer of a
lightly hydrogenated titanium alloy consisting of 50 to 80 wt% Ti
and 20 to 50 wt% Al.
7. The multilayer system as claimed in one of claims 1, 2 and 4 to
6, wherein the following multilayer structure:
glass/SnO2/TiO2/NiCrOx/ZnO:AI/Zn/Ag/TiAI (TiHℓ) /ZnO:AI/Si3
N4/ZnSnSbOx/Zn2TiO4 .
8. The multilayer system as claimed in one of claims 1, 2 and 4 to
6, wherein the following multilayer structure:
glass/SnO2/TiO2/ITO/ZnO: AI/Zn/Ag/TiAl (TiHℓ) / ZnO:AI / Si3N4/
ZnSnSbOx/Zn2TiO4.


ABSTRACT

Title: A heat-resistant low-emissivity multilayer system for
transparent substrates.
A heat-resistant low-E multilayer system for transparent substrates, in
particular for window panes, which has a lower antireflection coating
having a high-refringence layer, a wetting layer consisting essentially
of ZnO to which a silver-based functional layer is joined, a barrier
layer over the functional layer, an upper antireflection coating
consisting of a layer or several partial layers and a cover coating
consisting of a layer or several partial layers, another metal oxide
layer that serves as antiscattering layer being placed in the lower
antireflection coating between the high-refringence layer and the
wetting layer, characterized in that the antiscattering layer located
between the high-refringence layer and the wetting layer is a mixed
oxide layer with a thickness of at least 0.5 nm, made of NiCrOx or
InSnOx (ITO).

Documents:

00624-kolnp-2008-abstract.pdf

00624-kolnp-2008-claims.pdf

00624-kolnp-2008-correspondence others.pdf

00624-kolnp-2008-description complete.pdf

00624-kolnp-2008-form 1.pdf

00624-kolnp-2008-form 2.pdf

00624-kolnp-2008-form 3.pdf

00624-kolnp-2008-form 5.pdf

00624-kolnp-2008-gpa.pdf

00624-kolnp-2008-international publication.pdf

00624-kolnp-2008-international search report.pdf

00624-kolnp-2008-pct request form.pdf

624-KOLNP-2008-(21-11-2012)-ABSTRACT.pdf

624-KOLNP-2008-(21-11-2012)-ANNEXURE TO FORM 3.pdf

624-KOLNP-2008-(21-11-2012)-CLAIMS.pdf

624-KOLNP-2008-(21-11-2012)-CORRESPONDENCE.pdf

624-KOLNP-2008-(21-11-2012)-FORM-1.pdf

624-KOLNP-2008-(21-11-2012)-FORM-2.pdf

624-KOLNP-2008-(21-11-2012)-OTHERS.pdf

624-KOLNP-2008-(21-11-2012)-PA.pdf

624-KOLNP-2008-(21-11-2012)-PETITION UNDER RULE 137.pdf

624-KOLNP-2008-CANCELLED COPY.pdf

624-KOLNP-2008-CORRESPONDENCE OTHERS-1.1.pdf

624-KOLNP-2008-CORRESPONDENCE.pdf

624-KOLNP-2008-EXAMINATION REPORT.pdf

624-kolnp-2008-form 18.pdf

624-KOLNP-2008-FORM 181.1.pdf

624-KOLNP-2008-GPA.pdf

624-KOLNP-2008-GRANTED-ABSTRACT.pdf

624-KOLNP-2008-GRANTED-CLAIMS.pdf

624-KOLNP-2008-GRANTED-DESCRIPTION (COMPLETE).pdf

624-KOLNP-2008-GRANTED-FORM 1.pdf

624-KOLNP-2008-GRANTED-FORM 2.pdf

624-KOLNP-2008-GRANTED-FORM 3.pdf

624-KOLNP-2008-GRANTED-FORM 5.pdf

624-KOLNP-2008-GRANTED-SPECIFICATION-COMPLETE.pdf

624-KOLNP-2008-INTERNATIONAL PUBLICATION.pdf

624-KOLNP-2008-INTERNATIONAL SEARCH REPORT & OTHERS.pdf

624-KOLNP-2008-OTHERS.pdf

624-KOLNP-2008-PETITION UNDER RULE 137.pdf

624-KOLNP-2008-PRIORITY DOCUMENT.pdf

624-KOLNP-2008-REPLY TO EXAMINATION REPORT.pdf

624-KOLNP-2008-TRANSLATED COPY OF PRIORITY DOCUMENT.pdf


Patent Number 256794
Indian Patent Application Number 624/KOLNP/2008
PG Journal Number 31/2013
Publication Date 02-Aug-2013
Grant Date 30-Jul-2013
Date of Filing 12-Feb-2008
Name of Patentee SAINT-GOBAIN GLASS FRANCE
Applicant Address 18, AVENUE D'ALSACE, F-92400 COURBEVOIE
Inventors:
# Inventor's Name Inventor's Address
1 IHLO, LARS AN DEN LINDEN 50, 04889 PFLUCKUFF, ALLEMAGNE
2 COMTESSE, RALF FELDSTRASSE 9, 66787 WADGASSEN, ALLEMAGNE
3 SCHICHT, HEINZ DORFSTRASSE 72, D-06925 BETHAU, ALLEMAGNE
4 SCHMIDT, UWE OSTSTRASSE 7, 04895 FALKENBERG, ALLEMAGNE
PCT International Classification Number C03C 17/36
PCT International Application Number PCT/FR2006/050797
PCT International Filing date 2006-08-10
PCT Conventions:
# PCT Application Number Date of Convention Priority Country
1 102005039707.7 2005-08-23 Germany