Description:FORM 2
THE PATENTS ACT, 1970
(39 OF 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See section 10; rule 13)
Title: “GLASS COATING STACK AND METHOD THEREOF”
APPLICANT DETAILS:
(a) NAME: Asahi India Glass Limited
(b) NATIONALITY: IN
(c) ADDRESS: 203-208, Tribhuwan Complex, Ishwar Nagar, Mathura Road, New Delhi-
110065.
PREAMBLE TO THE DESCRIPTION:
The following specification particularly describes the nature of the invention and the manner
in which it is to be performed:
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GLASS COATING STACK AND METHOD THEREOF
Field of the Invention
The present invention relates to glass coating stacks and method thereof. The glass coating
stack is based on hybrid layer stack, which absorbs and neutralizes the internal reflection more
efficiently along with reducing the film side reflection and preventing pinholes and oxidation
spots.
Background of the Invention
The following background discussion includes information that may be useful in understanding
the present invention. It is not an admission that any of the information provided herein is prior
art or relevant to the presently claimed invention, or that any publication specifically or
implicitly referenced is prior art.
Most glass products would not have the properties that make them so useful without coatings.
Application of coatings are an essential part of glass manufacturing. Automotive coatings and
the processes used to coat automobile surfaces exemplify the avant-garde of technologies that
are capable of producing durable surfaces.
The coatings known currently suffers with various drawbacks like:
a) Higher Internal reflection
b) Uniformity of the colour from one to one end of the glass is also difficult to maintain
due to change in index of the layer in silicon nitride;
c) Achieving the suitable percentage transmission or reflection and as-well-as color values
in the shades of green, blue and bronze shades are very difficult;
d) Storage of glass under humid conditions after heat treatment which destroys the
performance of glasses. The failures of glass performance are related to optical,
chemical and mechanical durability;
e) The visual performance of the glass without the overcoat/ protective layer results in
damage of functional layer (white spots) in the coated stack;
f) Storing of glasses in humidity chamber for more than 24 hours without the protective
layer/ over coat results to damage the quality of the film;
g) Furthermore, the overall durability of the stored coated glasses without protective layer
at elevated temperatures at 650 degrees is also at risk. During this treatment process,
the stack of coatings are damaged due to increased stress, phase changes and instability.
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Hence, there is a need of an efficient glass coating, based on hybrid layer stack, which
overcomes the above-mentioned technical problem by providing an efficient glass coating
stack, which absorb and neutralizes the internal reflection more efficiently, which reduces the
film side reflection and prevents pinholes and oxidation spots. The glass coating with reduced
internal reflection, help the user to see the objects clearly outside the glass and not the selfreflection.
Object(s) of the Invention:
A primary object of the present invention is to overcome the drawbacks associated with the
prior art.
Yet another object of the present invention is to provide an efficient glass coating, based on
hybrid layer stack, which overcomes the above-mentioned technical problem by providing an
efficient glass coating stack, which absorb and neutralizes the internal reflection more
efficiently, which reduces the film side reflection and prevents pinholes and oxidation spots.
Yet another object of the present invention is to provide a process for the production of the
efficient glass coating, as described above.
Yet another object of the present invention is to provide a coated article with LOW E coating
reflecting layer system comprising specific layers of chromium and silicon Nitride layers.
Yet another object of the present invention is to provide a glass coating with reduced internal
reflection that helps user to see the objects clearly outside the glass and not the reflection of
oneself.
Yet another object of the present invention is to provide a coated article with IR reflecting layer
system comprising specific layers of chromium and dielectric silicon nitride layers.
Yet another object of the present invention is to provide a coated article with IR reflecting
layers comprising layers to absorb and neutralize the internal reflection.
Yet another object of the present invention is to provide a coated article with LOW E coating
comprising absorbing layers for reducing Film side reflection.
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Yet another object of the present invention is to provide a coated article with IR reflecting layer
system, which essentially comprises dielectric nitride layers of chromium and silicon for
preventing pinholes and oxidation spots.
Detail Description of the Drawings
To further clarify advantages and features of the present invention, a more particular
description of the invention will be rendered by reference to specific embodiments thereof,
which is illustrated in the appended drawings. It is appreciated that these drawings depict only
typical embodiments of the invention and are therefore not to be considered limiting of its
scope. The invention will be described and explained with additional specificity and detail with
the accompanying drawings in which:
Figure 1 illustrates the protective overcoat layer of Silicon Aluminium Zirconium Hafnium
Tungsten (SiAlZrHfW) deposited on the float glass substrate.
Figure 2 illustrates hybrid model ad novel developed product layer stack by adding a protective
overcoat layer deposited on float clear glass substrate using RF/DC magnetron sputtering.
Figure 3 and/ or Fig. 3A and 3B illustrates a cross-sectional view of the hybrid layer stack
coated article (heat treated or not heat treated) without over coat layer according to an example
embodiment of this invention.
Figure 4 and/ or Fig. 4A and 4B illustrates a cross-sectional view of the hybrid layer stack
coated article (heat treated or not heat treated) with over coat layer according to an example
embodiment of this invention
Detailed Description of the Invention
For the purpose of promoting an understanding of the principles of the invention, reference will
now be made to the embodiment illustrated in the drawings and specific language will be used
to describe the same. It will nevertheless be understood that no limitation of the scope of the
invention is thereby intended, such alterations and further modifications in the illustrated
system, and such further applications of the principles of the invention as illustrated therein
being contemplated as would normally occur to one skilled in the art to which the invention
relates.
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It will be understood by those skilled in the art that the foregoing general description and the
following detailed description are exemplary and explanatory of the invention and are not
intended to be restrictive thereof. Throughout the patent specification, a convention employed
is that in the appended drawings, like numerals denote like components.
Reference throughout this specification to “an embodiment, “another embodiment, “an
implementation, “another implementation” or similar language means that a particular feature,
structure, or characteristic described in connection with the embodiment is included in at least
one embodiment of the present invention. Thus, appearances of the phrase “in an embodiment,
“in another embodiment, “in one implementation, “in another implementation, and similar
language throughout this specification may, but do not necessarily, all refer to the same
embodiment.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a
non-exclusive inclusion, such that a process or method that comprises a list of steps does not
include only those steps but may include other steps not expressly listed or inherent to such
process or method.
The Invention provides an efficient glass coating, based on hybrid layer stack, which can
absorb and neutralizes the internal reflection more efficiently, which reduces the film side
reflection and prevents pinholes and oxidation spots.
In an embodiment, the invention provides a coated article with LOW E coating reflecting layer
system comprising specific layers of chromium and silicon Nitride layers.
In an embodiment, the invention provides a coated article with IR reflecting layer system
comprising specific layers of chromium and dielectric silicon nitride layers.
In an embodiment, the invention provides a coated article with IR reflecting layers comprising
layers to absorb and neutralize the internal reflection.
In an embodiment, the invention provides a coated article with LOW E coating comprising
absorbing layers for reducing Film side reflection.
In an embodiment, the invention provides a coated article with IR reflecting layer system,
which essentially comprises dielectric nitride layers of chromium and silicon for preventing
pinholes and oxidation spots.
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In an aspect, the invention provides a thin film coating stack, which is a product family of low
emissivity coating, in which the addition of chromium (Cr) and silicon aluminium nitride
(Si3AlN4) layer is an essential step.
In an embodiment, the glass coating layer comprises the following components:
a) Overcoat protective layer of SiAlZrHfWNyOx
b) SiAl OR Si3N4 OR SiAlN OR Si3AlNO
c) Cr OR CrN
d) SiAl OR Si3N4 OR SiAlN OR Si3AlNO
e) NiCr OR NiCrN
f) Ag
g) NiCr OR NiCrN
h) SiAl OR Si3N4 OR SiAlN OR Si3AlNO
i) Glass Thickness
The addition of chromium layer in the single silver and double silver low emissivity coating
stack provides better efficiency in reducing the internal reflection also improves the solar heat
gain coefficient.
In an embodiment, the glass coating comprises the layers in the following thickness:
Table 1
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In an embodiment, the additional layer of protective overcoat layer, chromium and silicon layer
can be used in both ways with and without presence of oxygen (Ox) and nitrogen (Ny).
In an embodiment, the present invention also provides a mechanism for changing the
stoichiometry of the layer, by changing the gas ratio and gas properties to develop a novel
graded index layer in the products of single and double low E products (Graded index means:
Index of the refraction of the any specific material in the layer stack will vary)
In an embodiment, the invention provides coated article including the low Emissivity coatings
with single layer of silver and as wells as double layer of silver as a functional layer in the
coated stack.
In an embodiment, the coated article herein used in the context of large scale glass industries
for the applications of laminated and double glazing window/ aesthetic glazing applications.
In an embodiment, the layer stack comprises a chromium nitride layer which is used to reduce
the internal reflection for the applications which are related to solar control and low emissivity
applications.
In an embodiment, the layer stack comprises approx. eight layers of thin films, as shown on
Fig.1.
In an embodiment, the coating of the present invention can be developed by the following
process:
a) The whole fabrication of developed product was produced by Physical Vapour
Deposition (PVD) technique. The coating system which was used is large area RF/DC
magnetron sputtering technique.
b) The entire coating process is carried out in high vacuum at a pressure of 10 x E-6 mbar.
The chamber is evacuated to achieve such high pressure vacuum by using both low and
high pressure pumps. In order to create low pressure (10 x E-3 mbar) vacuum roots and
rotary pump were used, simultaneously in order to create high vacuum (10 x E-6 mbar)
the turbo molecular pump is used. All the layers were deposited on glass substrate in
room temperature environment.
In an embodiment, the entire coating process of each layer was deposited in a sequential layer
method by passing the glass from each cathode chamber. During the coating process, the Argon
gas is used to create a 4th state of matter plasma.
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In an embodiment, while injecting Ar gas, the electric field acts to ionise the neutral argon Ar
atoms, causing them to accelerate toward the negatively charged target) for depositing the
layers on glass substrate.
In an embodiment, the developed uppermost/ over coated layer may be used in context of
various glass buildings, insulated glass window units, Glazing systems, vehicles, windows in
interior and exterior of buildings or in other suitable applications. The coated layer stack here
in will be used in said applications such as double glazed windows, and/or the like.
The experiments shows following technical/ functional properties:
a) Reduction in internal reflection
b) Addition of chromium nitride and silicon nitride layers in the Single silver low e stacks
reduces the internal reflection/film side reflection as compared to earlier stack which
does not have chromium nitride layers
c) Addition of chromium nitride, Silicon aluminium nitride layers and overcoat layers
shows a better performance after tempering the substrate at 650°C
d) The layer stack have better performance in both pre and post heating conditions with
minimum colour variation.
The above mentioned technical advantages are being achieved by the present invention by
including the top most layer of the coated stack with suitable dielectric composite layer. The
suitable hybrid layer stack with chromium nitride, silicon aluminium nitride are used to achieve
better performance in both pre and post tempering conditions.
Controlling of color performance in both times at pre and post conditions is also achieved by
hybrid layer design using the materials of chromium nitride (CrN) and silicon aluminium
nitride (Si3AlN4).
In an embodiment, the coating layer of the present invention comprises a Top layer dielectric
over coat layer, which can be combined with corrosion resistant material / dielectric oxide layer
of SiAlZrHfW OxNy.
In an embodiment, the developed product was fabricated by Physical Vapour Deposition
(PVD) technique using RF/DC magnetron sputtering coating system. The process fabrication
of layer coating is developed under low pressure vacuum via controlled environment. For
developing the product the float clear glass substrates having 300 x 300 mm dimension with 6
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to 12 mm thickness were used. To remove all the surface impurities, prior to the coating all the
glasses were cleaned via washer for 5minutes.
All the coating chambers are evacuated via turbo molecular pump to attain a base pressure of
10-6 mbar. Once the base pressure reaches to 10-6 mbar the actual deposition is carried out at a
pressure of 10-3 to 10-4 mbar. To obtain/achieve suitable property of the layer composition and
maintain the layer stoichiometry the Oxygen (Ox) and Nitrogen (Ny) gases or mixture of
reactive and inert (Ar) gas environment were used/carried in a controlled SCCM via Mass flow
controllers.
In further embodiments, the layers of silicon aluminium nitride (Si3AlN4), and Chromium
Nitride (CrN), Nickle chrome (NiCr), Zinc Oxide (ZnO), Silicon Aluminium Zirconium
Hafnium Tungsten (SiAlZrHfW) is deposited in the presence of Oxygen (Ox) and Nitrogen
(Ny). After deposition of layer on the hybrid coated layer stack, and upon heating, the deposited
nitride layer may become oxygenated and may result in, silicon aluminium oxy nitride or
silicon aluminium nitride, chromium nitride, Silicon aluminium hafnium tungsten doped
zirconium oxide layer. Such layer can be used as a protective/over coat layer in certain example
embodiments.
For an instance, the developed invention with hybrid layer stack may be used as an overcoat/
protective layer in single silver low emissivity coating. The Low emissivity coating comprises
infrared (IR) reflecting layer of silver and other alternative materials in certain other
embodiments. Other IR reflecting material layer like Nickle chromium, Niobium, gold alloys
and thereof etc.
All the developed coatings were characterized and tested in terms of optical, colour,
mechanical, elemental properties via UV-VIS-NIR Spectrophotometry, Hunter, Wet abrasion,
and x-ray fluorescence spectroscopy.
The coating stack of the present invention has applications in the following areas:
• The hybrid layer stack/coated article herein used in the context of large scale glass
industries for the applications of laminated and double glazing window/ aesthetic
glazing applications.
• The coated article herein used for industrial and socio economic areas.
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• The coated article also used in residential and commercial building development
agencies.
• The coated article also used in developing of green energy airport buildings,
commercial towers etc.
The Invention is further described with the help of non-limiting examples;
Example 1:
The experiments were performed with the above mentioned coating in Table 1, to find out the
Transmission properties (TrY), Reflection properties (Rf Y) and Rg Y properties.
single
glaze
unit
Tr Y 25 to 80 30 to 75 30 to 70
Rg Y 3 to 50 5 to 45 5 to 38
Rf Y 3 to 40 8 to 35 10 to 30
Double
glaze
unit
Tr Y 25 to 80 30 to 75 30 to 70
Rg Y 10 to 50 20 to 40 10 to 35
Rf Y 3 to 40 8 to 35 10 to 30
Example 2:
(Please provide analysis of the above table i.e. what are the positive results coming from the
positive experiments and what are the negative results coming from the positive experiments)
Example 3:
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The most effective amount of the argon gas useful for the preparation of the glass coating
(particularly for deposition of chromium layer) is 200 to 800 while of the Nitrogen gas is 200
to 1500. It was found that when the amount of the gases were disturbed from the claimed
range, the glass coating was not produced with the desirable properties in terms of reducing
the internal reflection.
Example 4: , Claims:We Claim:
1. A glass coating with reduced internal refection comprising:
a) an overcoat protective layer of SiAlZrHfWNyOx
b) atleast a layer of SiAl OR Si3N4 OR SiAlN OR Si3AlNO
c) atleast a layer of Cr OR CrN
d) atleast a layer of SiAl OR Si3N4 OR SiAlN OR Si3AlNO
e) atleast a layer of NiCr OR NiCrN
f) atleast a layer of Ag
g) atleast a layer of NiCr OR NiCrN
h) atleast a layer of SiAl OR Si3N4 OR SiAlN OR Si3AlNO
i) Glass
2. The glass coating as claimed in claim 1, where in the layers comprises following
thickness:
a) overcoat protective layer of SiAlZrHfWNyOx, present in the thickness of 1 to 30nm
b) atleast a layer of SiAl OR Si3N4 OR SiAlN OR Si3AlNO present in the thickness of 20
to 150nm
c) atleast a layer of Cr OR CrN present in the thickness of 1 to 30nm
d) atleast a layer of SiAl OR Si3N4 OR SiAlN OR Si3AlNO present in the thickness of 20
to 150nm
e) atleast a layer of NiCr OR NiCrN present in the thickness of 1 to 15nm
f) atleast a layer of Ag present in the thickness of 1 to 35nm
g) atleast a layer of NiCr OR NiCrN present in the thickness of 1 to 15nm
h) atleast a layer of SiAl OR Si3N4 OR SiAlN OR Si3AlNO present in the thickness of 20
to 150nm
i) Glass with the thickness of 2.5 to 12 mm
3. The glass coating as claimed in claim 1, wherein the layer of protective overcoat
layer, chromium and silicon layer are assembled with and without presence of oxygen
(Ox) and nitrogen (Ny).
4. The glass coating as claimed in claim 1, wherein argon gas ratio of 200 to 800 was
employed for the deposition of chromium layer.
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5. The glass coating as claimed in claim 1, wherein nitrogen gas ratio of 200 to 1500 was
employed for the deposition of chromium layer.
6. A method of preparing the glass coating as claimed in claim 1, wherein the coating
process over a substrate/ glass is carried out in high vacuum at a pressure of 10 x E-6
mbar, by the steps of:
a) Evacuating the chamber to achieve high pressure vacuum by using both low and high
pressure pumps wherein the low pressure (10 x E-3 mbar) is created by vacuum roots and rotary
pump, simultaneously in order to create high vacuum (10 x E-6 mbar) while, the high vacuum
(10 x E-6 mbar) is created by turbo molecular pump;
b) depositing the layers in a sequential layer method by passing the glass from each cathode
chamber while during the coating process, the argon gas is used to create a 4th state of matter
plasma.
7. The method as claimed in claim 6, wherein while injecting argon gas, the electric field acts
to ionise the neutral argon Ar atoms, causing them to accelerate towards the negatively charged
target for depositing the layers on glass substrate.
8. The method as claimed in claim 6, wherein the substrate after deposition of chromium
nitride, silicon aluminium nitride layers and overcoat layers is tempered at 650°C.