U.S. patent application number 16/756608 was filed with the patent office on 2020-08-20 for method of making a reflective coated glass article.
This patent application is currently assigned to PILKINGTON GROUP LIMITED. The applicant listed for this patent is PILKINGTON GROUP LIMITED. Invention is credited to MATTHEW BARRINGTON MAHONEY, NEIL MCSPORRAN, SRIKANTH VARANASI.
Application Number | 20200262748 16/756608 |
Document ID | 20200262748 / US20200262748 |
Family ID | 1000004865773 |
Filed Date | 2020-08-20 |
Patent Application | download [pdf] |
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United States Patent
Application |
20200262748 |
Kind Code |
A1 |
VARANASI; SRIKANTH ; et
al. |
August 20, 2020 |
METHOD OF MAKING A REFLECTIVE COATED GLASS ARTICLE
Abstract
A method of making a reflective coated glass article includes
providing a glass substrate. A first gaseous mixture is formed. The
first gaseous mixture includes a silane compound and inert gas. The
first gaseous mixture is delivered to a location above a major
surface of the glass substrate to deposit a first coating layer
directly on the major surface of the glass substrate. The first
coating layer is deposited at a thickness of 5-50 nm. A second
gaseous mixture is formed. The second gaseous mixture includes a
silane compound, a radical scavenger and molecular oxygen. The
second gaseous mixture is delivered to a location above the first
coating layer. A second coating layer is deposited at a thickness
of 5-50 nm over the first coating layer. The coated glass article
exhibits a total visible light reflectance (Illuminant D65, ten
degree observer) of 45% or more from a coated side of the coated
glass article.
Inventors: |
VARANASI; SRIKANTH; (OTTAWA
HILLS, OH) ; MCSPORRAN; NEIL; (LIVERPOOL, GB)
; MAHONEY; MATTHEW BARRINGTON; (PINEHURST, NC) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
PILKINGTON GROUP LIMITED |
LATHOM |
|
GB |
|
|
Assignee: |
PILKINGTON GROUP LIMITED
LATHOM
GB
|
Family ID: |
1000004865773 |
Appl. No.: |
16/756608 |
Filed: |
October 5, 2018 |
PCT Filed: |
October 5, 2018 |
PCT NO: |
PCT/GB2018/052859 |
371 Date: |
April 16, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62574437 |
Oct 19, 2017 |
|
|
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C03C 17/3482 20130101;
C03C 2218/1525 20130101 |
International
Class: |
C03C 17/34 20060101
C03C017/34 |
Claims
1.-26. (canceled)
27. A method of making a reflective coated glass article
comprising: providing a glass substrate; forming a first gaseous
mixture comprising a silane compound and inert gas and delivering
the first gaseous mixture to a location above a major surface of
the glass substrate to deposit a first coating layer directly on
the major surface of the glass substrate, wherein the first coating
layer is deposited at a thickness of 5-50 nm; and forming a second
gaseous mixture comprising a silane compound, molecular oxygen, and
a radical scavenger, and delivering the second gaseous mixture to a
location above the first coating layer and depositing a second
coating layer at a thickness of 5-50 nm over the first coating
layer, wherein the coated glass article exhibits a total visible
light reflectance (Illuminant D65, ten degree observer) of 45% or
more from the coated side of the coated glass article.
28. The method of claim 27, wherein the glass substrate is a glass
ribbon in a float glass manufacturing process.
29. The method of claim 27, wherein the glass substrate is
moving.
30. The method of claim 27, wherein the first coating layer has a
refractive index of 3.0 or more and the second coating layer has a
refractive index of less than 1.6.
31. The method of claim 27, wherein the first coating layer
comprises elemental silicon and the second coating layer comprises
silicon dioxide.
32. The method of claim 27, further comprising feeding the first
gaseous mixture through a first coating apparatus and discharging
the first gaseous mixture from the first coating apparatus.
33. The method off claim 27, wherein the thickness of the first
coating layer is 10-30 nm.
34. The method of claim 27, wherein the first gaseous mixture
consists essentially of the silane compound and inert gas.
35. The method of claim 27, wherein the second coating layer is
deposited directly on the first coating layer and forms the
outermost layer of the coating.
36. The method of claim 27, wherein the second gaseous mixture
comprises an oxygen-containing compound.
37. The method of claim 27, wherein the thickness of the second
coating layer is 10-50 nm.
38. The method of claim 27, further comprising depositing a third
coating layer over the second coating layer, wherein the third
coating layer is deposited at a thickness of 50 nm or less.
39. The method of claim 27, wherein the coated glass article
exhibits a sheet resistance of greater than 1.0.times.10.sup.10
ohm/sq. and/or wherein the coated glass article exhibits a total
visible light transmittance (Illuminant D65, ten degree observer)
of 40% or less from the coated side of the coated glass
article.
40. The method of claim 27, wherein the total visible light
reflectance (Illuminant D65, ten degree observer) exhibited by
coated glass article from the coated side of the coated glass
article is 45-75% and/or wherein the coated glass article exhibits
an a* value (Illuminant D65, ten degree observer) from the coated
side of the coated glass article in the range of -6 to 6 and a b*
value (Illuminant D65, ten degree observer) from the coated side of
the coated glass article in the range of -6 to 6.
41. The method of claim 27, wherein the first coating layer
consists essentially of elemental silicon and/or wherein the second
coating layer consists essentially of silicon dioxide.
42. The method of claim 32, wherein the first gaseous mixture is
formed prior to being fed through the first coating apparatus
and/or further comprising feeding the second gaseous mixture
through a second coating apparatus and discharging the second
gaseous mixture from the second coating apparatus.
43. The method of claim 36, wherein the oxygen-containing compound
is water vapor.
44. The method of claim 38, wherein the third coating layer is
deposited directly on the second coating layer.
45. The method of claim 38, wherein the third coating layer defines
an outer surface of the coated glass article and/or wherein the
third coating layer comprises silicon oxide and fluorine.
46. The method of claim 27, wherein the coated glass article
exhibits a total visible light transmittance (Illuminant D65, ten
degree observer) of 20-40% from the coated side of the coated glass
article and/or wherein the a* value is negative and the b* value is
positive.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This application is claiming the benefit, under 35 U.S.C.
119(e), of the U.S. provisional patent application which was
granted Ser. No. 62/574,437 and filed on Oct. 19, 2017, the entire
disclosure of which is hereby incorporated by reference.
BACKGROUND
[0002] The invention relates to a method of making a coated glass
article. More particularly, the invention relates to a method of
making a reflective coated glass article.
[0003] Flat screen video displays are now found in many locations
in public and commercial facilities and in private homes. It has
been found to be desirable for such video displays to be less
obtrusive when the display is not in operation. One way to
accomplish this objective is to conceal the video display by giving
it the appearance of an object that might commonly appear in a room
such as a mirror. However, under certain conditions such as, for
example, when there are relatively high levels of natural light
illuminating a space and the video display is in operation, the
quality of the video image is not as bright or sharp as would be
desirable.
[0004] Thus, it would be advantageous to provide a method of making
a coated glass article that has a mirror-like appearance for
concealing a video display when the display is not in use and
permits a video image from the display to be bright and sharp when
the display is in use and utilized in areas with high levels of
natural light.
BRIEF SUMMARY
[0005] Embodiments of a method of making a reflective coated glass
article are provided. In an embodiment, the method comprises
providing a glass substrate. A first gaseous mixture is formed. The
first gaseous mixture comprises a silane compound and inert gas.
The first gaseous mixture is delivered to a location above a major
surface of the glass substrate to deposit a first coating layer
directly on the major surface of the glass substrate. The first
coating layer is deposited at a thickness of 5-50 nm. A second
gaseous mixture is formed. The second gaseous mixture comprises a
silane compound, a radical scavenger and molecular oxygen. The
second gaseous mixture is delivered to a location above the first
coating layer. A second coating layer is deposited at a thickness
of 5-50 nm over the first coating layer. The coated glass article
exhibits a total visible light reflectance (Illuminant D65, ten
degree observer) of 45% or more from a coated side of the coated
glass article.
[0006] In some embodiments, the glass substrate is moving.
[0007] In other embodiments, the glass substrate is a glass ribbon
in a float glass manufacturing process.
[0008] Preferably, the first coating layer has a refractive index
of 3.0 or more and the second coating layer has a refractive index
of less than 1.6.
[0009] Preferably, the first coating layer comprises elemental
silicon and the second coating layer comprises silicon dioxide. In
an embodiment, the first coating layer consists essentially of
elemental silicon. In another embodiment, the second coating layer
consists essentially of silicon dioxide.
[0010] In an embodiment, the first gaseous mixture is fed through a
first coating apparatus and the first gaseous mixture is discharged
from the first coating apparatus. Preferably, the first gaseous
mixture is formed prior to being fed through the first coating
apparatus.
[0011] In another embodiment, the second gaseous mixture is fed
through a second coating apparatus and the second gaseous mixture
is discharged from the second coating apparatus.
[0012] In an embodiment, the first gaseous mixture consists
essentially of the silane compound and inert gas.
[0013] In another embodiment, the second gaseous mixture comprises
an oxygen-containing compound. Preferably, the oxygen-containing
compound is water vapor.
[0014] In an embodiment, the thickness of the first coating layer
is 10-30 nm.
[0015] In another embodiment, the thickness of the second coating
layer is 10-50 nm.
[0016] In some embodiments, the second coating layer is deposited
directly on the first coating layer and forms the outermost layer
of the coating.
[0017] In certain embodiments, a third coating layer is deposited
over the second coating layer, wherein the third coating layer is
deposited at a thickness of 50 nm or less. In an embodiment, the
third coating layer is deposited directly on the second coating
layer. In another embodiment, the third coating layer defines an
outer surface of the coated glass article. In some embodiments, the
third coating layer comprises silicon oxide and fluorine.
[0018] In an embodiment, the coated glass article 10 exhibits a
sheet resistance of greater than 1.0.times.10.sup.10 ohm/sq.
[0019] In some embodiments, the total visible light reflectance
(Illuminant D65, ten degree observer) exhibited by coated glass
article from the coated side of the coated glass article is
45-75%.
[0020] In other embodiments, the coated glass article exhibits a
total visible light transmittance (Illuminant D65, ten degree
observer) of 40% or less from the coated side of the coated glass
article. In an embodiment, the coated glass article exhibits a
total visible light transmittance (Illuminant D65, ten degree
observer) of 20-40% from the coated side of the coated glass
article.
[0021] Preferably, the coated glass article exhibits an a* value
(Illuminant D65, ten degree observer) from the coated side of the
coated glass article in the range of -6 to 6 and a b* value
(Illuminant D65, ten degree observer) from the coated side of the
coated glass article in the range of -6 to 6.
[0022] In some embodiments, the a* value is negative and the b*
value is positive.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING
[0023] The above, as well as other advantages of the present
invention will become readily apparent to those skilled in the art
from the following detailed description when considered in the
light of the accompanying drawings in which:
[0024] FIG. 1 is a sectional view of an embodiment of a coated
glass article in accordance with an embodiment of the
invention;
[0025] FIG. 2 is a sectional view of another embodiment of a coated
glass article in accordance with another embodiment of the
invention; and
[0026] FIG. 3 is a schematic view, in vertical section, of an
installation for practicing the float glass manufacturing process
in accordance with an embodiment of the invention.
DETAILED DESCRIPTION
[0027] It is to be understood that the invention may assume various
alternative orientations and step sequences, except where expressly
specified to the contrary. It is also to be understood that the
specific layers, articles, methods and processes illustrated in the
attached drawings, and described in the following specification are
simply exemplary embodiments of the inventive concepts. Hence,
specific dimensions, directions, or other physical characteristics
relating to the embodiments disclosed are not to be considered as
limiting, unless expressly stated otherwise.
[0028] In an embodiment, a method of making a reflective coated
glass article is provided. The embodiments of the reflective coated
glass article 10 will be described below and with reference to
FIGS. 1-3. The embodiments of the coated glass article 10 may be
utilized as a single coated glass sheet. In one such embodiment,
the coated glass article is utilized as a portion of a display
assembly. Additionally, the embodiments of the coated glass article
10 may be utilized in, for example, a glazing and/or have
architectural, electronic, residential, commercial, photovoltaic,
automotive, and aerospace applications.
[0029] The method comprises providing a glass substrate.
Embodiments of the glass substrate are illustrated in, for example,
FIGS. 1 and 2. The transparency or absorption characteristics of
the glass substrate may vary between embodiments of the coated
glass article. Also, the color of the glass substrate can vary
between embodiments of method. In some embodiments, the glass
substrate may be tinted or colored. However, it is preferred that
the glass substrate 12 is substantially clear and transparent to
visible light.
[0030] The glass substrate may be of a conventional glass
composition known in the art. In certain embodiments, the
composition of the glass substrate 12 is selected to allow the
coated glass article 10 to exhibit certain properties. Preferably,
the glass substrate 12 is a soda-lime-silica glass. In this
embodiment, the substrate 12 may be a float glass ribbon. However,
the glass substrate may be of another composition such as, for
example, a borosilicate or an aluminosilicate composition.
Additionally, the glass substrate thickness may vary between
embodiments.
[0031] The method may be carried out in conjunction with the
manufacture of the glass substrate 12. In an embodiment, the glass
substrate 12 may be formed utilizing the well-known float glass
manufacturing process. An example of a float glass manufacturing
process is illustrated in FIG. 3. In this embodiment, the glass
substrate may also be referred to as a glass ribbon 38. However, it
should be appreciated that the method can be utilized apart from
the float glass manufacturing process or well after formation and
cutting of the glass ribbon.
[0032] A coating 14 is formed over the glass substrate 12.
Preferably, the coating 14 is formed directly on a first major
surface 20 of the glass substrate 12. When the coating 14 is formed
directly on the glass substrate 12, there are no intervening
coatings between the coating 14 and the glass substrate 12. A
second major surface 22 of the glass substrate 12 and an opposite
side of the coated glass article 10 may be uncoated.
[0033] In an embodiment, the coating 14 is pyrolytic. As used
herein, the term "pyrolytic" may refer to a coating or a layer
thereof that is chemically bonded to a glass substrate. Preferably,
the coating 14 is formed by two or more chemical vapor deposition
(CVD) processes. In certain embodiments, each CVD process is a
dynamic deposition process. Thus, in these embodiments, the glass
substrate 12 is moving at the time of forming the coating 14
thereon or thereover. Preferably, the glass substrate 12 moves at a
predetermined rate of, for example, greater than 3.175 m/min (125
in/min) as the coating 14 is being formed. In an embodiment, the
glass substrate 12 is moving at a rate of between 3.175 m/min (125
in/min) and 12.7 m/min (600 in/min) as the coating 14 is being
formed.
[0034] In certain embodiments, the glass substrate 12 is heated. In
embodiments where the substrate 12 is a float glass ribbon, the
coating 14 is preferably applied in the heated zone of the float
glass manufacturing process. In an embodiment, the temperature of
the glass substrate 12 is about 1100.degree. F. (593.degree. C.) or
more when a coating 14 is formed thereover or directly thereon. In
another embodiment, the temperature of the glass substrate 12 is
between about 1100.degree. F. (593.degree. C.) and 1400.degree. F.
(760.degree. C.) when the coating 14 is formed.
[0035] The coating 14 comprises a first coating layer 16 and a
second coating layer 18. In certain embodiments, the coating 14
consists of the aforementioned coating layers 16, 18. In these
embodiments, there are no intervening layers between the first
coating layer 16 and the second coating layer 18.
[0036] The first coating layer 16 is deposited over and,
preferably, directly on, the first major surface 20 of the glass
substrate 12. Preferably, the first coating layer 16 is deposited
over the first major surface 20 of the glass substrate 12 while the
surface is at essentially atmospheric pressure. In this embodiment,
the first coating layer 16 is deposited by an atmospheric pressure
chemical vapor deposition (APCVD) process. In certain embodiments,
the first coating layer 16 is pyrolytic.
[0037] In order to provide a coated glass article 10 that exhibits
the desired visible light reflectance, it is preferred that the
first coating layer 16 has a refractive index of 3.0 or more. In
certain embodiments, it may be preferred that the first coating
layer 16 has a refractive index of 3.4-3.5. It should be noted that
the refractive index values referred to herein are for an average
value across 400-780 nanometers (nm) of the electromagnetic
spectrum.
[0038] Preferably, in these embodiments, the first coating layer 16
comprises elemental silicon (Si). However, the first coating layer
16 may comprise other materials having a suitable refractive index.
Preferably, such other materials are also dielectric. When the
first coating layer 16 comprises elemental silicon, the silicon
layer may consist essentially of elemental silicon. In these
embodiments, the silicon layer may include trace contaminants of,
for example, carbon. As used herein, the phrase "trace amount" is
an amount of a constituent of a coating layer that is not always
quantitatively determinable because of its minuteness. However, it
is preferred that the silicon layer is essentially free of
contaminants such as carbon. In embodiments where the first coating
layer 16 comprises elemental silicon, the thickness of the first
coating layer 16 is 5-50 nm. Preferably, in these embodiments, the
thickness of the first coating layer 16 is 10-30 nm. More
preferably, the thickness of the first coating layer 16 is 10-25
nm.
[0039] The first coating layer 16 is deposited by forming a first
gaseous mixture. In certain embodiments, the first gaseous mixture
includes at least one reactant (precursor) compound suitable for
forming the first coating layer at essentially atmospheric
pressure. It is preferred that the at least one precursor compound
suitable for use in the gaseous mixture is suitable for use in a
CVD process. Such compounds may at some point be a liquid or a
solid but are volatile such that they can be vaporized for use in
the gaseous mixture. Once in a gaseous state, the at least one
precursor compound can be included in a gaseous stream and utilized
to deposit the first coating layer 16.
[0040] When the first coating layer 16 comprises elemental silicon,
the first coating layer 16 may be deposited by forming a first
gaseous mixture that comprises a silane compound. The silane
compound is provided by delivering the silane compound from a
source of the silane compound. In an embodiment, the silane
compound is monosilane (SiH.sub.4). However, other silane compounds
may be suitable for use in depositing the first coating layer
16.
[0041] The first gaseous mixture may also comprise a radical
scavenger. Thus, a source of a radical scavenger may also be
provided for supplying the radical scavenger. In an embodiment, the
radical scavenger is a hydrocarbon gas. Preferably, the hydrocarbon
gas is ethylene (C.sub.2H.sub.4) or propylene (C.sub.3H.sub.6).
[0042] However, it is preferred that the first coating layer is
essentially free of contaminants such as, for example, carbon.
Thus, in certain embodiments, it is preferred that a radical
scavenger is not provided in the first gaseous mixture. In these
embodiments, the first gaseous mixture may comprise the silane
compound and inert gas. In certain embodiments, the first gaseous
mixture may consist essentially of the silane compound and inert
gas. The inert gas may be utilized as carrier or diluent gas.
Suitable inert gases for inclusion in the first gaseous mixture
include nitrogen (N.sub.2), helium (He), and mixtures thereof.
[0043] In some embodiments, the silane compound is mixed with inert
gas to form the first gaseous mixture. In certain embodiments, the
first gaseous mixture is fed through a first coating apparatus and
discharged from the first coating apparatus utilizing one or more
gas distributor beams. Preferably, the first gaseous mixture is
formed prior to being fed through the first coating apparatus. For
example, the silane compound and inert gas may be mixed in a feed
line connected to an inlet of the first coating apparatus. In other
embodiments, the gaseous mixture may be formed within the first
coating apparatus.
[0044] Preferably, the first coating apparatus extends transversely
across the glass substrate and is provided at a predetermined
distance there above. The coating apparatus is preferably located
at, at least, one predetermined location. When the method is
utilized in conjunction with the float glass manufacturing process,
the coating apparatus is preferably provided within the float bath
section thereof. However, the coating apparatus may be provided in
the annealing lehr, and/or in the gap between the float bath and
the annealing lehr.
[0045] The first gaseous mixture is delivered to a location above
the first major surface 20 of the glass substrate 12. The first
gaseous mixture is directed toward and along the glass substrate.
Utilizing the first coating apparatus aids in delivering the first
gaseous mixture to a location above the glass substrate 12 and
directing the first gaseous mixture toward and along the glass
substrate. Preferably, the first gaseous mixture is directed toward
and along the glass substrate in a laminar flow.
[0046] The first gaseous mixture reacts at or near the glass
substrate to deposit the first coating layer thereover. Utilizing
the embodiments of the first gaseous mixture described above
results in the deposition of a high quality coating layer on the
glass substrate. In particular, the first coating layer exhibits
excellent coating thickness uniformity and can be deposited at
commercial viable deposition rates.
[0047] The second coating layer 18 is deposited over and,
preferably, directly on the first coating layer 16. When the second
coating layer 18 is deposited directly on the first coating layer
16, there are no intervening layers between the first coating layer
16 and the second coating layer 18. In certain embodiments, the
second coating layer 18 is the outermost coating layer of the
coated glass article 10. In these embodiments, the second coating
layer 18 defines an outer surface 24 of the coated glass article
10.
[0048] The second coating layer 18 comprises a dielectric material.
Also, in order to provide a coated glass article 10 that exhibits
the desired visible light reflectance, it is preferred that the
second coating layer 18 has a refractive index that is less than
the refractive index of the first coating layer 16. In certain
embodiments, the refractive index of the second coating layer is
1.6 or less. In these embodiments, it is preferred that the second
coating layer 18 comprises silicon dioxide (SiO.sub.2). Silicon
dioxide is a preferred material because it is dielectric and has a
refractive index of about 1.46. In some embodiments, the second
coating layer 18 consists essentially of silicon dioxide.
[0049] Preferably, the second coating layer 18 is pyrolytic. In
embodiments where the second coating layer 18 comprises silicon
dioxide, the thickness of the second coating layer 18 is 5-50 nm.
Preferably, for these embodiments, the thickness of the second
coating layer 18 is 10-50 nm.
[0050] Preferably, the second coating layer 18 is deposited by
forming a second gaseous mixture. In certain embodiments, the
second gaseous mixture includes precursor compounds suitable for
forming the second coating layer 18 at essentially atmospheric
pressure. It is preferred that the precursor compounds suitable for
use in the second gaseous mixture are suitable for use in a CVD
process. Such compounds may at some point be a liquid or a solid
but are volatile such that they can be vaporized for use in the
second gaseous mixture. Once in a gaseous state, the precursor
compounds can be included in a gaseous stream and utilized to form
the second coating layer 18.
[0051] When the second coating layer 18 comprises silicon dioxide,
the second gaseous mixture comprises a silane compound. The second
gaseous mixture also comprises a radical scavenger and molecular
oxygen (O.sub.2). In an embodiment, the second gaseous mixture
consists essentially of the silane compound, radical scavenger, and
molecular oxygen. Further, in some embodiments, the second gaseous
mixture may comprise an oxygen-containing compound. In one such
embodiment, the second gaseous mixture consists essentially of the
silane compound, radical scavenger, molecular oxygen, and an
oxygen-containing compound.
[0052] In an embodiment, the silane compound is monosilane
(SiH.sub.4). However, other silane compounds are suitable for use
in depositing the second coating layer 18. For example, disilane
(Si.sub.2H.sub.6) is a suitable silane compound for use in
depositing the second coating layer 18.
[0053] The silane compound utilized in the second gaseous mixture
may be pyrophoric. When molecular oxygen alone is added to the
second gaseous mixture, which comprises a pyrophoric silane
compound, silicon dioxide is produced. However, the silicon dioxide
is produced at unacceptably high rates and an explosive reaction
may result. Known methods of preventing such a reaction result in
the deposition of coatings at very low, commercially impractical
rates. Known methods are also limited in the amount of silane
compound and oxygen which can be contained in the gaseous mixture,
as too high a concentration results in gas phase reaction of the
elements, and no coating layer being produced. Therefore, it is
preferred that the second gaseous mixture includes the radical
scavenger.
[0054] The presence of the radical scavenger allows the silane
compound to be mixed with molecular oxygen and/or an
oxygen-containing compound without undergoing ignition and
premature reaction at the operating temperatures. The radical
scavenger further provides control of and permits optimization of
the kinetics of the reaction above, near, and/or on the glass
substrate 12. In an embodiment, the radical scavenger is a
hydrocarbon gas. Preferably, the hydrocarbon gas is ethylene
(C.sub.2H.sub.4) or propylene (C.sub.3H.sub.6).
[0055] Molecular oxygen can be provided as a part of a gaseous
composition such as air or in a substantially purified form. In
embodiments where the second gaseous mixture comprises an
oxygen-containing compound, it is preferred that the
oxygen-containing compound is water (H.sub.2O) vapor. In an
embodiment, the second gaseous mixture comprises both molecular
oxygen and water vapor. In this embodiment, the second gaseous
mixture may comprise more water vapor than molecular oxygen.
[0056] The second gaseous mixture may also comprise one or more
inert gases utilized as carrier or diluent gas. Suitable inert
gases include nitrogen (N.sub.2), helium (He), and mixtures
thereof. Thus, sources of the one or more inert gases, from which
separate supply lines may extend, may be provided.
[0057] In an embodiment, the second gaseous mixture is formed by
mixing the silane compound, radical scavenger, and molecular
oxygen. In some embodiments, the second gaseous mixture is formed
by mixing the silane compound, radical scavenger, molecular oxygen,
and oxygen-containing compound. In certain embodiments, after
mixing, the second gaseous mixture is fed through a second coating
apparatus and discharged from the second coating apparatus
utilizing one or more gas distributor beams. Preferably, the second
gaseous mixture is formed prior to being fed through the second
coating apparatus. For example, the silane compound, molecular
oxygen, and radical scavenger may be mixed in a feed line connected
to an inlet of the second coating apparatus. In other embodiments,
the second gaseous mixture may be formed within the second coating
apparatus.
[0058] The second gaseous mixture is delivered to a location above
the first coating layer 16. The second gaseous mixture is directed
toward and along the glass substrate 12. Utilizing the second
coating apparatus aids in delivering the second gaseous mixture to
a location above the first coating layer 16 and directing the
second gaseous mixture toward and along the glass substrate 12.
Preferably, the second gaseous mixture is directed toward and along
the glass substrate 12 in a laminar flow.
[0059] The second gaseous mixture reacts at or near the glass
substrate 12 to form the second coating layer 18 thereover.
Utilizing the embodiments of the second gaseous mixture described
above results in the deposition of a high quality coating layer
over the glass substrate 12 and first coating layer 16. In
particular, the second coating layer 18 exhibits excellent coating
thickness uniformity.
[0060] The embodiments of the method described above provide a
coated glass article 10 that is highly reflective. The high
reflectivity exhibited by the coated glass article 10 allows a
display such as, for example, a flat screen television to be
concealed by the reflectance and mirror-like appearance of the
coated glass article 10 when the display is not in use. Also, when
the display is in use, a display image is visible through the
coated glass article 10 and the quality of the display image
visible through the article 10 is bright and sharp under a broad
spectrum of ambient light conditions. In some embodiments, it may
be preferred that the coating 14 faces out and away from the
display.
[0061] The reflectivity of the coated glass article will be further
discussed below with respect to its total visible light
reflectance. For describing the coated glass article 10, total
visible light reflectance will refer to the percentage of visible
light reflected from the coated glass article 10 as measured from
the side 26 of the coated glass article 10 that has the coating 14
formed on the surface of the glass substrate 12 (coated side).
Also, for describing the coated glass article 10, total visible
light transmittance will refer to the percentage of visible light
passing through the coated glass article 10 as measured from the
coated side 26 of the coated glass article 10. The total visible
light reflectance and total visible light transmittance will be
described herein according to the CIELAB color scale system using
Illuminant D65, ten degree observer.
[0062] Advantageously, the coated glass article 10 exhibits a total
visible light reflectance (Illuminant D65, ten degree observer) of
45% or more. Preferably, the coated glass article 10 exhibits a
total visible light reflectance (Illuminant D65, ten degree
observer) of 50% or more. In certain embodiments, the coated glass
article 10 exhibits a total visible light reflectance (Illuminant
D65, ten degree observer) of 60% or more. Preferably, in these
embodiments, the coated glass article 10 exhibits a total visible
light reflectance (Illuminant D65, ten degree observer) of 65% or
more. In these embodiments, the coated glass article 10 may exhibit
a total visible light reflectance (Illuminant D65, ten degree
observer) of 75% or less. Thus, for example, the coated glass
article 10 may exhibit a total visible light reflectance
(Illuminant D65, ten degree observer) of 45-75%. Total visible
light reflectance can be measured using a commercially available
spectrophotometer such as the Perkin Elmer Lambda 950.
[0063] Additionally, in an embodiment, the coated glass article 10
exhibits a total visible light transmittance (Illuminant D65, ten
degree observer) of 40% or less. Preferably, the coated glass
article 10 exhibits a total visible light transmittance (Illuminant
D65, ten degree observer) of 35% or less. In certain embodiments,
the coated glass article 10 exhibits a total visible light
transmittance (Illuminant D65, ten degree observer) of 30% or less.
In further embodiments, the coated glass article 10 may exhibit a
total visible light transmittance (Illuminant D65, ten degree
observer) of 25% or less. In these embodiments, the coated glass
article 10 may exhibit a total visible light transmittance
(Illuminant D65, ten degree observer) of at least 20%. Thus, for
example, the coated glass article 10 may exhibit a total visible
light transmittance (Illuminant D65, ten degree observer) of
20-40%. Total visible light transmittance can be measured using a
commercially available spectrophotometer such as the Perkin Elmer
Lambda 950.
[0064] The coated glass article 10 may also exhibit other
properties that are advantageous. For example, it should also be
noted that the coated glass article 10 not only exhibits a high
total visible light reflectance but may also exhibit a neutral
color for the visible light reflected from the coated side 26 of
the coated glass article 10 when viewed at a 90 degree angle
incident to the coated glass article 10. The color of the visible
light reflected from the coated side 26 of the coated glass article
10 may be referred to herein as "reflected color." The reflected
color will be described herein according to the CIELAB color scale
system using Illuminant D65, ten degree observer. Reflected color
can be measured using a commercially available spectrophotometer
such as the Perkin Elmer Lambda 950. Also, for the purpose of
describing the embodiments of the coated glass article 10 disclosed
herein, a neutral color for the visible light reflected from the
coated side 26 of the coated glass article 10 has an a* value
(Illuminant D65, ten degree observer) in the range of -6 to 6 and a
b* value (Illuminant D65, ten degree observer) in the range of -6
to 6.
[0065] Preferably, the coated glass article 10 exhibits a reflected
color in a range from about -4 to 3 for the a* value (Illuminant
D65, ten degree observer) and a range from about -3 to 3 for the b*
value (Illuminant D65, ten degree observer). More preferably, the
coated glass article 10 exhibits a reflected color in a range from
about -3 to 3 for the a* value (Illuminant D65, ten degree
observer) and a range from about -3 to 3 for the b* value
(Illuminant D65, ten degree observer). In these embodiments, it is
preferred that the coated glass article 10 exhibits a reflected
color in which the a* value is negative and the b* value is
positive. It should be appreciated that a negative a* value
indicates a green color hue and a negative b* value indicates a
yellow color hue for the reflected color exhibited by the coated
glass article 10.
[0066] Also, the coated glass article 10 may exhibit a low haze
value. As discussed herein, the term "haze" refers to the
percentage of incident visible light that scatters when passing
through the coated glass article 10. Also, as discussed herein, the
haze exhibited by the coated glass article 10 is measured from the
coated side 26 of the coated glass article 10. In an embodiment,
the coated glass article 10 may exhibit haze of 0.5% or less.
Preferably, the coated glass article 10 exhibits a haze of 0.4% or
less. In some embodiments, the haze exhibited by the coated glass
article 10 is 0.1-0.4%. The haze exhibited by the coated glass
article 10 can be measured using a commercially available haze
meter such as the BYK-Gardner haze-gard plus.
[0067] In certain embodiments, the coated glass article 10 may be
utilized in a touch screen electronic device. The touch screen
electronic device may be of the projected capacitive touch,
optical, or the infrared variety. When the coated glass article 10
is utilized in a touch screen electronic device, the coated glass
article 10 is provided in the device such that the coating 14 faces
out from the device and, when the touch screen electronic device is
in use, the user controls the device by touching the coating 14. In
these embodiments, it is preferred that the coated glass article 10
exhibits a high sheet resistance. In one such embodiment, the
coated glass article 10 exhibits a sheet resistance of, for
example, greater than 1.0.times.10.sup.10 ohm/sq. Preferably, the
coated glass article 10 exhibits a sheet resistance of
1.0.times.10.sup.12 ohm/sq. or more. The coated glass article
exhibits a sheet resistance of, for example, greater than
1.0.times.10.sup.10 ohm/sq. by proper selection of the composition
and thickness of each of the first coating layer and the second
coating layer. The sheet resistance exhibited by coated glass
article 10 is measured on the coated side 26 of the coated glass
article 10. The sheet resistance exhibited by coated glass article
10 can be measured using a 4-point probe method and a commercially
available 4-point probe.
[0068] Furthermore, in certain embodiments such as, for example,
when the coated glass article 10 is utilized in a touch screen
electronic device, the coated glass article 10 may comprise a third
coating layer 28. With reference now to FIG. 2, the third coating
layer 28 is deposited over and, preferably, directly on the second
coating layer 18. When the third coating layer 28 is deposited
directly on the second coating layer 18, there are no intervening
layers between the second coating layer 18 and the third coating
layer 28. In these embodiments, the third coating layer 28 may be
the outermost coating layer of the coated glass article 10. In
these embodiments, the third coating layer 28 may define the outer
surface 24 of the coated glass article 10.
[0069] In certain embodiments, the third coating layer 28 can be
utilized to allow the coated glass article 10 to exhibit
hydrophobic and/or oleophobic properties. Advantageously, when the
coated glass article 10 exhibits hydrophobic properties, the coated
glass article 10 repels water and resists soiling. When the coated
glass article 10 exhibits oleophobic properties, the coated glass
article 10 resists oil and fingerprints being deposited on the
coated glass article 10. In these embodiments, the third coating
layer 28 may comprise silicon, oxygen, and fluorine. In one such
embodiment, the third coating layer 28 comprises silicon oxide and
fluorine. In these embodiments, the third coating layer 28 may be
deposited by utilizing a fluorosilane compound or a
fluoroalkylsilane compound. When the third coating layer 28 is
provided, the third coating layer 28 may be deposited at a
thickness of 50 nm or less. In certain embodiments, it is preferred
that the thickness of the third coating layer 28 is 5-10 nm. In
these embodiments, the third coating layer 28 may be deposited
utilizing, for example, a sputter deposition process or a solution
deposition process such as, for example, a dipping process or a
spinning process. However, the third coating layer 28 may be
deposited using other deposition processes.
[0070] As discussed, above, the coating 14 may be formed in
conjunction with the manufacture of the glass substrate 12 in the
well-known float glass manufacturing process. The float glass
manufacturing process is typically carried out utilizing a float
glass installation such as the installation 30 depicted in the FIG.
3. However, it should be understood that the float glass
installation 30 described herein is only illustrative of such
installations.
[0071] As illustrated in FIG. 3, the float glass installation 30
may comprise a canal section 32 along which molten glass 34 is
delivered from a melting furnace, to a float bath section 36
wherein the glass substrate is formed. In this embodiment, the
glass substrate will be referred to as a glass ribbon 38. The glass
ribbon 38 is a preferable substrate on which the coating is formed.
However, it should be appreciated that the glass substrate is not
limited to being a glass ribbon.
[0072] The glass ribbon 38 advances from the bath section 36
through an adjacent annealing lehr 40 and a cooling section 42. The
float bath section 36 includes: a bottom section 44 within which a
bath of molten tin 46 is contained, a roof 48, opposite side walls
(not depicted) and end walls 50, 52. The roof 48, side walls and
end walls 50, 52 together define an enclosure 54 in which a
non-oxidizing atmosphere is maintained to prevent oxidation of the
molten tin 46.
[0073] In operation, the molten glass 34 flows along the canal 32
beneath a regulating tweel 56 and downwardly onto the surface of
the tin bath 46 in controlled amounts. On the molten tin surface,
the molten glass 34 spreads laterally under the influence of
gravity and surface tension, as well as certain mechanical
influences, and it is advanced across the tin bath 46 to form the
glass ribbon 38. The glass ribbon 38 is removed from the bath
section 36 over lift out rolls 58 and is thereafter conveyed
through the annealing lehr 40 and the cooling section 42 on aligned
rolls. The deposition of the coating 14 preferably takes place in
the float bath section 36, although it may be possible for
deposition to take place further along the glass production line,
for example, in the gap 60 between the float bath 36 and the
annealing lehr 40, or in the annealing lehr 40.
[0074] As illustrated in the FIG. 3, two coating apparatuses 62, 64
are shown within the float bath section 36. The coating 14 may be
formed utilizing the coating apparatuses 62, 64 with each coating
apparatuses utilized to deposit one of the coating layers 16, 18.
For example, in an embodiment, the first coating layer 16 is
deposited utilizing the first coating apparatus 62. In this
embodiment, the second coating layer 22 is deposited utilizing the
second coating apparatus 64.
[0075] A suitable non-oxidizing atmosphere, generally nitrogen or a
mixture of nitrogen and hydrogen in which nitrogen predominates, is
maintained in the float bath section 36 to prevent oxidation of the
molten tin 46 comprising the float bath. The atmosphere gas is
admitted through conduits 70 operably coupled to a distribution
manifold 72. The non-oxidizing gas is introduced at a rate
sufficient to compensate for normal losses and maintain a slight
positive pressure, on the order of between about 0.001 and about
0.01 atmosphere above ambient atmospheric pressure, so as to
prevent infiltration of outside atmosphere. For purposes of the
describing the invention, the above-noted pressure range is
considered to constitute normal atmospheric pressure.
[0076] Preferably, the coating 14 is formed at essentially
atmospheric pressure. Thus, the pressure of the float bath section
36, annealing lehr 40, and/or in the gap 60 between the float bath
36 and the annealing lehr 40 may be essentially atmospheric
pressure.
[0077] Heat for maintaining the desired temperature regime in the
float bath section 36 and the enclosure 54 is provided by radiant
heaters 74 within the enclosure 54. The atmosphere within the lehr
40 is typically atmospheric air, as the cooling section 42 is not
enclosed and the glass ribbon 38 is therefore open to the ambient
atmosphere. The glass ribbon 38 is subsequently allowed to cool to
ambient temperature. To cool the glass ribbon 38, ambient air may
be directed against the glass ribbon 38 as by fans 76 in the
cooling section 42. Heaters (not depicted) may also be provided
within the annealing lehr 40 for causing the temperature of the
glass ribbon 38 to be gradually reduced in accordance with a
predetermined regime as it is conveyed therethrough.
Examples
[0078] The following examples are presented solely for the purpose
of further illustrating and disclosing the embodiments of the
method of making the coated glass article.
[0079] Examples of coated glass articles within the scope of the
invention are described below and illustrated in TABLE 1. In TABLE
1, the coated glass articles within the scope of the invention are
Ex 1-Ex 4. A comparative example, not considered to be a part of
the invention, is also described below and illustrated in TABLE
1.
[0080] The comparative example is designated as C1 in TABLE 1. The
following experimental conditions are applicable to C1. For C1, a
coating was deposited on a first major surface of a glass substrate
as the glass substrate was being formed and moving in conjunction
with the float glass manufacturing process. The glass substrate was
of a soda-lime-silica composition. The coating was formed by
depositing a first coating layer, second coating layer, third
coating layer and fourth coating layer. Each coating layer was
formed by utilizing an APCVD process.
[0081] For C1, the first coating layer was pyrolytic and comprised
tin oxide and was deposited at a thickness of 29.7 nm. The first
coating layer was deposited directly on the first major surface of
the glass substrate. After depositing the first coating layer, the
second coating layer was deposited at a thickness of 84.4 nm. The
second coating layer was pyrolytic and comprised silicon dioxide.
The second coating layer was deposited directly on the first
coating layer. After depositing the second coating layer, the third
coating layer was deposited at a thickness of 29.8 nm. The third
coating layer was pyrolytic and comprised tin oxide. The third
coating layer was deposited directly on the second coating layer.
After depositing the third coating layer, the fourth coating layer
was deposited at a thickness of 35.8 nm. The fourth coating layer
was pyrolytic comprised titanium dioxide. The fourth coating layer
was deposited directly on the third coating layer. Thus, the coated
glass article of C1 was of a
glass/SnO.sub.2/SiO.sub.2/SnO.sub.2/TiO.sub.2 arrangement.
[0082] The following experimental conditions are applicable to Ex
1-Ex 4. For Ex 1-Ex 4, a coating was deposited on a first major
surface of a glass substrate as the glass substrate was being
formed and moving in conjunction with the float glass manufacturing
process. The glass substrate was of a soda-lime-silica composition.
The coating was formed by depositing a first coating layer and a
second coating layer. Each coating layer was formed by utilizing an
APCVD process.
[0083] For Ex 1-Ex 4, the first coating layer was pyrolytic and
comprised elemental silicon. For Ex 1-Ex 4, the first coating layer
was deposited by forming a first gaseous mixture. For Ex 1-Ex 4,
each first gaseous mixture comprised monosilane (SiH.sub.4) and
inert gas. For Ex 1, the mole percentage (mol %) of monosilane in
the first gaseous mixture was 1.4, with the remainder of the
gaseous mixture comprising inert gas. For Ex 2, the first gaseous
mixture comprised 2.5 mol % monosilane with the remainder of the
gaseous mixture comprising inert gas. For Ex 3, the first gaseous
mixture comprised 2.5 mol % monosilane with the remainder of the
gaseous mixture comprising inert gas. For Ex 4, the first gaseous
mixture comprised 1.4 mol % monosilane with the remainder of the
gaseous mixture comprising inert gas. For each of Ex 1-Ex 4, the
monosilane and inert gas was mixed to form the first gaseous
mixture. Each first gaseous mixture was fed through a coating
apparatus before being delivered to a location above a first major
surface of a respective glass substrate of Ex1-Ex 4.
[0084] Each first coating layer was deposited directly on the first
major surface of the respective glass substrate. For Ex 1, the
first coating layer was deposited at a thickness of 16 nm. For Ex
2, the first coating layer was deposited at a thickness of 22 nm.
For Ex 3, the first coating layer was deposited at a thickness of
21.6 nm. For Ex 4, the first coating layer was deposited at a
thickness of 16.3 nm. The first coating layer was deposited
directly on the first major surface of the glass substrate.
[0085] After depositing the first coating layer, the second coating
layer was deposited. The second coating layer was pyrolytic and
comprised silicon dioxide. For Ex 1-Ex 4, the second coating layer
was deposited by forming a second gaseous mixture. For each of Ex
1-Ex 4, the second gaseous mixture comprised monosilane
(SiH.sub.4), molecular oxygen (O.sub.2), ethylene (C.sub.2H.sub.4),
and inert gas. For Ex 1, the second gaseous mixture comprised 0.16
mol % monosilane, 0.7 mol % molecular oxygen, and 1.0 mol %
ethylene, with the remainder of the gaseous mixture comprising
inert gas. For Ex 2, the second gaseous mixture comprised 0.4 mol %
monosilane, 1.6 mol % molecular oxygen, and 2.4 mol % ethylene,
with the remainder of the gaseous mixture comprising inert gas. For
Ex 3, the second gaseous mixture comprised 0.35 mol % monosilane,
1.4 mol % molecular oxygen, and 2.1 mol % ethylene, with the
remainder of the gaseous mixture comprising inert gas. For Ex 4,
the second gaseous mixture comprised 0.2 mol % monosilane, 0.8 mol
% molecular oxygen, and 1.2 mol % ethylene, with the remainder of
the gaseous mixture comprising inert gas. For each of Ex 1-Ex 4,
the precursor compounds and inert gas were mixed to form the second
gaseous mixture. Each second gaseous mixture was fed through a
coating apparatus before being delivered to a location above a
respective first coating layer of Ex 1-Ex 4.
[0086] Each second coating layer was deposited directly on the
respective first coating layer. For Ex 1, the second coating layer
was deposited at a thickness of 32.4 nm. For Ex 2, the second
coating layer was deposited at a thickness of 14.2 nm. For Ex 3,
the second coating layer was deposited at a thickness of 20.9 nm.
For Ex 4, the second coating layer was deposited at a thickness of
38.9 nm. Thus, the coated glass articles of Ex 1-Ex 4 are of a
glass/Si/SiO.sub.2 arrangement.
[0087] The thicknesses of the coating layers of Ex 1-Ex 4 and C1,
which are reported above, were calculated via optical modeling. The
haze, total visible light transmittance (Tvis) (Illuminant D65, ten
degree observer), total visible light reflectance (Rf) (Illuminant
D65, ten degree observer) and reflected color (Ra*, Rb*)
(Illuminant D65, ten degree observer) of the coated glass articles
of Ex 1-Ex 4 and C1 are reported in TABLE 1. The haze was measured
on the coated side of each coated glass article using a BYK-Gardner
haze-gard plus and is expressed as a percentage. The total visible
light transmittance and was measured on the coated side of each
coated glass article using a Perkin Elmer Lambda 950
spectrophotometer and is expressed as a percentage. The total
visible light reflectance and reflected color were measured on the
coated side of each coated glass article using a Perkin Elmer
Lambda 950 spectrophotometer. The total visible light reflectance
is expressed as a percentage.
TABLE-US-00001 TABLE 1 Examples Haze Tvis Rf Ra* Rb* C1 0.84 52.5
44.6 -7.8 -2.8 Ex 1 0.36 34.2 52.9 -2.98 -1.95 Ex 2 0.35 22.3 66.6
-2.39 0.10 Ex 3 0.35 30.3 62.6 -3.85 -0.54 Ex 4 0.31 39.3 53.1
-3.58 -0.31
[0088] As shown in TABLE 1, the coated glass articles of Ex1-Ex 4
exhibit improved reflectance properties when compared with the
coated glass article of C1. For example, the coated glass articles
of Ex 1-Ex 4 each exhibited a total visible light reflectance
(Illuminant D65, ten degree observer) of more than 45%. In stark
contrast, the coated glass article of C1 exhibited a total visible
light reflectance (Illuminant D65, ten degree observer) of less
than 45%. In fact, the coated glass articles of Ex 1-Ex 4 each
exhibited a total visible light reflectance (Illuminant D65, ten
degree observer) of more than 50% and the coated glass article of
Ex 2 exhibited a total visible light reflectance (Illuminant D65,
ten degree observer) of more than 65%. It should also be noted that
the coated glass articles of Ex 1-Ex 4 exhibited a neutral color
for the visible light reflected from the coated side of each coated
glass article.
[0089] Also, the method of making the coated glass articles of Ex
1-Ex 4 exhibited other advantageous properties. For example, the
coated glass articles of Ex 1-Ex 4 only required a first gaseous
mixture to deposit the first coating layer and a second gaseous
mixture to deposit the second coating layer. Thus, the coated glass
articles of Ex 1-Ex 4 are less expensive and complex to manufacture
than the coated glass article of C1, which required four gaseous
mixtures. Additionally, the method of making the coated glass
articles of Ex 1-Ex 4 allowed the coated glass article to each
exhibit a haze below 0.4%. In stark contrast, the method utilized
to make the coated glass article of C1, resulted in a coated glass
article that exhibited a haze of 0.84%. Furthermore, the coated
glass articles of Ex 1-Ex 4 each exhibited sheet resistances that
would allow them to be utilized in projected capacitive touch
screen devices. For example, the coated glass article of Ex 3
exhibited a sheet resistance of 3.04.times.10.sup.12 ohm/sq. and
the coated glass article of Ex 4 exhibited a sheet resistance of
1.22.times.10.sup.13 ohm/sq. The sheet resistances reported for the
coated glass articles of Ex 3 and the coated glass article of Ex 4
were measured on the coated side of each coated glass article using
a 4-point probe method and a commercially available 4-point
probe.
[0090] The foregoing description is considered as illustrative only
of the principles of the invention. Further, since numerous
modifications and changes will readily occur to those skilled in
the art, it is not desired to limit the invention to the exact
construction and processes shown and described herein. Accordingly,
all suitable modifications and equivalents may be considered as
falling within the scope of the invention as defined by the claims,
which follow.
* * * * *