U.S. patent application number 10/767914 was filed with the patent office on 2005-08-04 for high performance blue glass.
Invention is credited to Arbab, Mehran, Heithoff, Robert B., Shelestak, Larry J., Smith, Dennis G..
Application Number | 20050170944 10/767914 |
Document ID | / |
Family ID | 34807763 |
Filed Date | 2005-08-04 |
United States Patent
Application |
20050170944 |
Kind Code |
A1 |
Arbab, Mehran ; et
al. |
August 4, 2005 |
High performance blue glass
Abstract
A glass composition for forming a blue colored glass is
disclosed. The glass composition is made up of a base glass
portion, iron oxide, and at least one first additive compound
selected from Nd.sub.2O.sub.3 in an amount up to 1 weight percent
and/or CuO in an amount up to 0.5 weight percent. The base glass
portion has the following components: SiO.sub.2 from 66 to 75
weight percent; Na.sub.2O from 10 to 20 weight percent; CaO from 5
to 15 weight percent; MgO from 0 to 5 weight percent;
Al.sub.2O.sub.3 from 0 to 5 weight percent; B.sub.2O.sub.3 from 0
to 5 weight percent; and K.sub.2O from 0 to 5 weight percent. The
total iron in the glass composition ranges from 0.3 to 1.2 weight
percent, and the glass composition has a redox ratio ranging from
0.15 to 0.65.
Inventors: |
Arbab, Mehran; (Pittsburgh,
PA) ; Heithoff, Robert B.; (Gibsonia, PA) ;
Shelestak, Larry J.; (Bairdford, PA) ; Smith, Dennis
G.; (Butler, PA) |
Correspondence
Address: |
PPG INDUSTRIES, INC.
INTELLECTUAL PROPERTY DEPT.
ONE PPG PLACE
PITTSBURGH
PA
15272
US
|
Family ID: |
34807763 |
Appl. No.: |
10/767914 |
Filed: |
January 29, 2004 |
Current U.S.
Class: |
501/64 ;
501/70 |
Current CPC
Class: |
C03C 4/02 20130101; C03C
3/087 20130101; C03C 3/095 20130101; C03C 3/091 20130101 |
Class at
Publication: |
501/064 ;
501/070 |
International
Class: |
C03C 003/095; C03C
003/087 |
Claims
What is claimed is:
1. A glass composition for forming a blue colored glass comprising
a base glass portion comprising: a. SiO.sub.2 from 66 to 75 weight
percent; b. Na.sub.2O from 10 to 20 weight percent; c. CaO from 5
to 15 weight percent; d. MgO from 0 to 5 weight percent; e.
Al.sub.2O.sub.3 from 0 to 5 weight percent; f. B.sub.2O.sub.3 from
0 to 5 weight percent; and g. K.sub.2O from 0 to 5 weight percent;
and additives consisting essentially of: total iron from about 0.3
to 1.2 weight percent; at least one first additive compound
selected from Nd.sub.2O.sub.3 in an amount up to 1 weight percent,
CuO in an amount up to 0.5 weight percent, and combinations
thereof; and optionally one or more second additive compounds
selected from CoO, Cr.sub.2O.sub.3, V.sub.2O.sub.5, CeO.sub.2,
H.sub.2O, SO.sub.3, TiO.sub.2, ZnO, MoO.sub.3, NiO, Se,
La.sub.2O.sub.3, WO.sub.3, Er.sub.2O.sub.3, SnO.sub.2, and
MnO.sub.2, wherein the redox ratio of the composition ranges from
0.15 to 0.65 and the glass has a color characterized by a dominant
wavelength up to 500 nm and an excitation purity no greater than 18
percent at a thickness of 0.154 inches.
2. The glass composition of claim 1, wherein the redox ratio ranges
from 0.25 to 0.5.
3. The glass composition of claim 2, wherein the redox ratio ranges
from 0.35 to 0.40.
4. The glass composition of claim 1, wherein the total iron ranges
from 0.4 to 0.8 weight percent.
5. The glass composition of claim 1, wherein the glass has an LTA
of at least 70%, an ISO Tuv no greater than 45%, an SAE Tuv no
greater than 60%, an SAE Tsol no greater than 60%, and a TSIR no
greater than 45% at a thickness of 0.154 inches.
6. The glass composition of claim 1, wherein the glass has a color
characterized by a dominant wavelength up to 495 nm and an
excitation purity up to 15 percent at a thickness of 0.154
inches.
7. The glass composition of claim 5, wherein the glass has an ISO
Tuv no greater than 43% at a thickness of 0.154 inches.
8. The glass composition of claim 5, wherein the glass has an SAE
Tuv no greater than 58% at a thickness of 0.154 inches.
9. The glass composition of claim 5, wherein the glass has an SAE
Tsol no greater than 57% at a thickness of 0.154 inches.
10. The glass composition of claim 5, wherein the glass has a TSIR
no greater than 35% at a thickness of 0.154 inches.
11. The glass composition of claim 1, wherein Nd.sub.2O.sub.3 is
present as the first additive compound.
12. The glass composition of claim 11, wherein Nd.sub.2O.sub.3 is
present in an amount up to 0.7 weight percent based on the total
weight of the glass composition.
13. The glass composition of claim 1, wherein CuO is present as the
first additive compound.
14. The glass composition of claim 13, wherein CuO is present in an
amount up to 0.3 weight percent based on the total weight of the
glass composition.
15. The glass composition of claim 1 wherein the first additive
compound comprises CuO and Nd.sub.2O.sub.3.
16. The glass composition of claim 1, wherein CoO is present as a
second additive compound in an amount up to 40 PPM.
17. The glass composition of claim 1, wherein Cr.sub.2O.sub.3 is
present as a second additive compound in an amount up to 100
PPM.
18. The glass composition of claim 1, wherein CeO.sub.2 is present
as a second additive compound in an amount up to 3.0 weight percent
based on the total weight of the glass composition.
19. A glass composition comprising a base glass portion comprising:
a. SiO.sub.2 from 66 to 75 weight percent; b. Na.sub.2O from 10 to
20 weight percent; c. CaO from 5 to 15 weight percent; d. MgO from
0 to 5 weight percent; e. Al.sub.2O.sub.3 from 0 to 5 weight
percent; f. B.sub.2O.sub.3 from 0 to 5 weight percent; and g.
K.sub.2O from 0 to 5 weight percent; and additives consisting
essentially of: total iron from about 0.3 to 1.2 weight percent; at
least one first additive compound selected from the group
Nd.sub.2O.sub.3 in an amount up to 1 weight percent, CuO in an
amount up to 0.5 weight percent, and combinations thereof; and
optionally one or more second additive compounds selected from CoO,
Cr.sub.2O.sub.3, V.sub.2O.sub.5, CeO.sub.2, H.sub.2O, SO.sub.3,
TiO.sub.2, ZnO, MoO.sub.3, NiO, Se, La.sub.2O.sub.3, WO.sub.3,
Er.sub.2O.sub.3, SnO.sub.2, and MnO.sub.2, wherein the redox ratio
of the composition ranges from 0.15 to 0.65, and wherein the glass
composition at a thickness of 0.154 inches has an LTA of at least
70%, an ISO Tuv no greater than 45%, an SAE Tuv no greater than
60%, an SAE Tsol no greater than 60%, and a TSIR no greater than
45%.
20. The glass composition of claim 19, wherein the glass has an ISO
Tuv no greater than 43% at a thickness of 0.154 inches.
21. The glass composition of claim 19, wherein the glass has an SAE
Tuv no greater than 55% at a thickness of 0.154 inches.
22. The glass composition of claim 19, wherein the glass has an SAE
Tsol no greater than 55% at a thickness of 0.154 inches.
23. The glass composition of claim 19, wherein the glass has a TSIR
no greater than 40% at a thickness of 0.154 inches.
24. The glass composition of claim 19, wherein the glass has a
color characterized by a dominant wavelength no greater than 500 nm
and an excitation purity no greater than 18 percent at a thickness
of 0.154 inches.
25. The glass composition of claim 19 wherein the redox ratio
ranges from 0.25 to 0.50.
26. The glass composition of claim 24, wherein the glass has a
color characterized by a dominant wavelength up to 495 nm and an
excitation purity up to 15 percent at a thickness of 0.154
inches.
27. A glass composition comprising a base glass portion comprising:
a. SiO.sub.2 from 66 to 75 weight percent; b. Na.sub.2O from 10 to
20 weight percent; c. CaO from 5 to 15 weight percent; d. MgO from
0 to 5 weight percent; e. Al.sub.2O.sub.3 from 0 to 5 weight
percent; f. B.sub.2O.sub.3 from 0 to 5 weight percent; and g.
K.sub.2O from 0 to 5 weight percent; and additives consisting
essentially of: total iron from about 0.3 to 1.2 weight percent;
and at least one first additive compound selected from
Nd.sub.2O.sub.3 in an amount up to 1 weight percent, CuO in an
amount up to 0.5 weight percent, and combinations thereof, wherein
the redox ratio of the composition ranges from 0.15 to 0.65 and the
glass composition has an LTA of at least 70%, an ISO Tuv no greater
than 45%, an SAE Tuv no greater than 60%, an SAE Tsol no greater
than 60%, and a TSIR no greater than 45% at a thickness of 0.154
inches.
28. A glass composition according to claim 27, wherein the glass
has a color characterized by a dominant wavelength no greater than
500 nm and an excitation purity no greater than 18 percent at a
thickness of 0.154 inches.
29. A method for making blue colored glass comprising a. mixing a
glass composition according to claim 1; and b. melting the glass
composition.
30. The method of claim 29, wherein the made glass comprises at
least one piece of glass in an automobile windshield.
31. The method of claim 29, wherein the made glass comprises at
least one piece of glass in an architectural structure.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to glass compositions for
forming a blue colored glass; especially glass compositions
comprising iron oxides, neodymium oxide and/or copper oxide.
BACKGROUND
[0002] Glass is used in a variety of products ranging from
buildings to automotive products. Depending on the end use of the
glass, the glass will be required to have certain color and other
performance properties like infrared radiation absorption,
ultraviolet radiation absorption, visible light absorption, total
solar energy absorption, etc.
[0003] In order to produce glass having a specific color and other
performance properties, various additives are added to a base glass
composition. A typical base glass composition comprises Na.sub.2O,
CaO, MgO, Al.sub.2O.sub.3, SiO.sub.2 and K.sub.2O. Typical
additives to a base glass composition include compounds containing
iron, cobalt, nickel, selenium, chromium, titanium, etc.
[0004] For certain commercial applications, blue colored glass
having certain solar performance is required. A multitude of
compositions for forming blue glass are well known to those of
skill in the art. For example, U.S. Pat. No. 6,313,053 discloses a
composition that yields a blue colored glass. To form the blue
glass, additives such as ferric oxide (Fe.sub.2O.sub.3) and a
reducing agent such as coal, are added to a base glass composition.
The reducing agent is used to control the amount of ferrous oxide
(FeO) in the composition.
[0005] Glass compositions having a lower redox ratio are generally
preferred over those having a higher redox ratio because glass
compositions having a lower redox ratio are easier to melt, refine,
and cool, therefore generally less costly to process.
[0006] The present invention provides a novel glass composition for
forming blue colored glass comprising iron oxides, neodymium oxide
and/or copper oxide. The glass composition of the present invention
can have an iron redox ratio of 0.15 to 0.65, for example, from
0.25 to 0.50, and solar energy blocking properties.
SUMMARY OF THE INVENTION
[0007] In one non-limiting embodiment, the present invention is a
glass composition for forming a blue colored glass having a base
glass portion comprising: SiO.sub.2 from 66 to 75 weight percent,
Na.sub.2O from 10 to 20 weight percent, CaO from 5 to 15 weight
percent, MgO from 0 to 5 weight percent, Al.sub.2O.sub.3 from 0 to
5 weight percent, B.sub.2O.sub.3 from 0 to 5 weight percent, and
K.sub.2O from 0 to 5 weight percent, and additives consisting
essentially of: total iron from about 0.3 to 1.2 weight percent; at
least one first additive compound selected from Nd.sub.2O.sub.3 in
an amount up to 1 weight percent and/or CuO in an amount up to 0.5
weight percent; and optionally one or more second additive
compounds selected from CoO, Cr.sub.2O.sub.3, V.sub.2O.sub.5,
CeO.sub.2, H.sub.2O, SO.sub.3, TiO.sub.2, ZnO, MoO.sub.3, NiO, Se,
La.sub.2O.sub.3, WO.sub.3, Er.sub.2O.sub.3, SnO.sub.2, and
MnO.sub.2, wherein the iron redox ratio of the composition ranges
from 0.15 to 0.65.
[0008] In another non-limiting embodiment, the present invention
provides a method for making blue colored glass comprising: mixing
a glass composition as discussed above; and melting the glass
composition.
DESCRIPTION OF THE INVENTION
[0009] All numbers expressing dimensions, physical characteristics,
quantities of ingredients, reaction conditions, and the like used
in the specification and claims are to be understood as being
modified in all instances by the term "about". Accordingly, unless
indicated to the contrary, the numerical values set forth in the
following specification and claims may vary depending upon the
desired properties sought to be obtained by the present invention.
At the very least, and not as an attempt to limit the application
of the doctrine of equivalents to the scope of the claims, each
numerical parameter should at least be construed in light of the
number of reported significant digits and by applying ordinary
rounding techniques. Moreover, all ranges disclosed herein are to
be understood to encompass any and all subranges subsumed therein.
For example, a stated range of "1 to 10" should be considered to
include any and all subranges between (and inclusive of) the
minimum value of 1 and the maximum value of 10; that is, all
subranges beginning with a minimum value of 1 or more and ending
with a maximum value of 10 or less, e.g., 1 to 7.8, 3 to 4.5, 6.3
to 10.
[0010] The present invention is a glass composition for a blue
colored glass. The glass composition of the present invention
comprises a base glass composition and additives consisting
essentially of iron oxide, at least one first additive compound
selected from Nd.sub.2O.sub.3 and/or CuO, and optionally one or
more second additive compounds, which are described below in more
detail.
[0011] The components of the base glass composition are shown in
the table below.
1 Weight percent range based on Component the total weight of the
composition SiO.sub.2 66 to 75 Na.sub.2O 10 to 20 CaO 5 to 15 MgO 0
to 5 Al.sub.2O.sub.3 0 to 5 B.sub.2O.sub.3 0 to 5 K.sub.2O 0 to
5
[0012] Additives can be added to the base glass composition to
obtain the required color and/or spectral properties, such as
infrared radiation absorption and ultraviolet radiation absorption.
Depending on the performance requirements of the glass, the
additives discussed below can be added to the base glass
composition.
[0013] According to the present invention, iron oxide is added to
the base glass composition. As discussed herein, iron oxide is
expressed in terms of the iron oxide in the ferric state
(Fe.sub.2O.sub.3) and the iron oxide in the ferrous state (FeO).
The total amount of iron oxide present in the glass composition
according to the present invention is expressed in terms of
Fe.sub.2O.sub.3 in accordance with standard analytical practice.
However, this is not meant to imply that all of the iron oxide
present in the composition is in the form of Fe.sub.2O.sub.3.
Similarly, when iron oxide is expressed in terms of FeO that does
not mean all of the iron oxide present is in the form FeO.
[0014] Iron oxides can be added to a glass composition to perform
several functions. Fe.sub.2O.sub.3 is known to those of skill in
the art to be a good ultraviolet radiation absorber and a yellow
colorant. FeO is known to those of skill in the art to be a good
infrared radiation absorber and a blue colorant.
[0015] The term "redox ratio" is used herein to reflect the
relative amounts of Fe.sub.2O.sub.3 and FeO in the glass
composition. As used herein, "redox ratio" means the amount of iron
as FeO in the composition divided by the total amount of iron in
the composition expressed in terms of Fe.sub.2O.sub.3.
[0016] Glass compositions according to present invention have total
iron ranging from 0.3 to 1.2, for example, 0.4 to 0.8 or 0.5 to 0.6
weight percent based on the total weight of the composition. The
redox ratio of a glass composition according to the present
invention ranges from 0.15 to 0.65, for example, 0.25 to 0.5, or
0.3 to 0.4.
[0017] In addition to iron oxide, at least one first additive
compound selected from neodymium oxide (Nd.sub.2O.sub.3) and copper
oxide (CuO) is added to the base glass composition according to the
present invention. In a non-limiting embodiment of the invention,
Nd.sub.2O.sub.3 is added to the base glass composition.
Nd.sub.2O.sub.3 is known in the art to be a violet colorant. The
amount of Nd.sub.2O.sub.3 in the glass composition of the present
invention can range up to 1 weight percent, for example, up to 0.7
weight percent, or up to 0.25 weight percent, based on the total
weight of the glass composition.
[0018] In a non-limiting embodiment of the invention, CuO is added
to the base glass composition. As used herein, CuO represents both
valence states of copper: cuprous, Cu.sup.+ and cupric, Cu.sup.2+.
Depending on the relative amounts of cuprous and cupric present in
the glass composition, the CuO will impart different properties to
the final glass. Cupric is known in the art as a blue colorant and
an infrared absorbing material. Cuprous is colorless in
compositions according to the present invention.
[0019] The relative amounts of cuprous and cupric present in the
glass composition of the invention are determined, in part, by the
amount of iron oxides present, the partial pressure of O.sub.2 in
the atmosphere above the glass during the melting process, and the
temperature of the glass. When iron and copper oxides are mixed
together, copper is reduced and iron is oxidized due to their
respective electrochemical potentials as is well known in the art.
The amount of CuO in the glass composition of the present invention
can be up to 0.5 weight percent, for example, up to 0.3 weight
percent or up to 0.2 weight percent, based on the total weight of
the composition.
[0020] In addition to the base glass composition constituents
described above, iron oxides as described above, and
Nd.sub.2O.sub.3 and/or CuO, the glass composition of the present
invention can optionally include one or more of the second additive
compounds described below.
[0021] In a non-limiting embodiment of the invention, cobalt (CoO)
is added to the base glass composition. CoO is known in the art to
be a blue colorant. The amount of CoO in the glass composition of
the present invention can range up to 40 parts per million ("ppm"),
for example, from 4 ppm to 30 ppm or from 5 ppm to 15 ppm.
[0022] In a non-limiting embodiment of the invention, chromium
(Cr.sub.2O.sub.3) is added to the base glass composition.
Cr.sub.2O.sub.3 is known to those of skill in the art to be a green
colorant. It also believed that Cr.sub.2O.sub.3 can provide some
ultraviolet radiation absorption. The amount of Cr.sub.2O.sub.3 in
the glass composition of the present invention can range up to 100
ppm, for example, from 5 ppm to 50 ppm or from 7 ppm to 30 ppm.
[0023] In a non-limiting embodiment of the invention, vanadium
(V.sub.2O.sub.5 ) is added to the base-glass composition.
V.sub.2O.sub.5 is known to those of skill in the art to act as a
yellow-green colorant and an absorber of both ultraviolet and
infrared radiation depending on the valence state of the vanadium
compound. Also, V.sub.2O.sub.5 can be used as a partial or complete
replacement for Cr.sub.2O.sub.3 in the glass composition. The
amount Of V.sub.2O.sub.5 in the glass composition of the present
invention can range up to 0.1 weight percent, based on the total
weight of the final glass composition.
[0024] Other second additive compounds that can be added the base
glass composition are shown in the table below. These compounds are
well known to those of ordinary skill in the art.
2 Weight Percent range based on the Component total weight of the
composition CeO.sub.2 0 to 3 TiO.sub.2 0 to 0.5 ZnO 0 to 0.5
MoO.sub.3 0 to 0.02 (0 to 200 ppm) NiO 0 to 0.001 (0 to 10 ppm) Se
0 to 0.0003 (0 to 3 ppm) La.sub.2O.sub.3 0 to 0.5 WO.sub.3 0 to 0.5
MnO.sub.2 0 to 0.5 Er.sub.2O.sub.3 0 to 1 SnO.sub.2 0 to 2
[0025] It should be appreciated that the glass compositions
disclosed herein can include small amounts of other materials, for
example, melting and refining aids, tramp materials or
impurities.
[0026] Glasses having different color and other performance
properties can be obtained by adding combinations of the additives
described above to the base glass composition. For example, in a
non-limiting embodiment of the invention, Fe.sub.2O.sub.3 can be
combined with Nd.sub.2O.sub.3 and/or CuO to provide a blue glass
having the desired spectral properties. In a non-limiting
embodiment of the invention, the blue glass has a dominant
wavelength up to 500 nm.
[0027] In a non-limiting embodiment, the glass composition of the
present invention is produced using a conventional float glass
process, which is well known to those skilled in the art. Suitable
float glass processes are disclosed in U.S. Pat. Nos. 3,083,551;
3,961,930; and 4,091,156, which are hereby incorporated by
reference.
[0028] In another non-limiting embodiment of the present invention,
glass can be produced using a multi-stage melting operation as
disclosed in U.S. Pat. Nos. 4,381,934; 4,792,536; and 4,886,539,
which are hereby incorporated by reference.
[0029] If required, a stirring arrangement that is well known in
the art can be employed within the melting and/or forming stages of
the glass production operation to homogenize the glass in order to
produce glass of the highest optical quality.
[0030] Because float glass processes involve suspending glass on
molten tin, measurable amounts of tin oxide (SnO.sub.2) can migrate
into portions of the glass that are in physical contact with the
molten tin during forming. Typically, a piece of glass produced by
a float glass process has an SnO.sub.2 concentration ranging from 0
to 2.0 weight percent in the first 25 microns below the surface of
the glass that was in contact with the tin. Typical background
levels of SnO.sub.2 in float glass can be as high as 30 ppm.
Although high concentrations of SnO.sub.2 in about the first 10
angstroms of the glass surface can slightly increase the
reflectivity of the glass surface, the overall impact of SnO.sub.2
on the properties of glass is minimal for most applications.
[0031] In a non-limiting embodiment of the present invention,
sulfur oxide (SO.sub.3) can be added to the base glass composition.
SO.sub.3 is known to those of ordinary skill in the art to be a
melting and refining aid for a soda-lime-silica glass composition.
Glass produced according to the present invention can include up to
0.3 weight percent SO.sub.3 based on the total weight of the
glass.
[0032] The combination of Fe.sub.2O.sub.3 and SO.sub.3 in a glass
composition can impart an amber coloration in the glass which
lowers luminous transmittance as discussed in U.S. Pat. No.
4,792,536. However, it is believed that the reducing conditions
required to produce the coloration in float glass compositions of
the type disclosed herein are limited to approximately the first 20
microns of the lower glass surface contacting the molten tin during
the float forming operation, and to a lesser extent, to the exposed
upper glass surface. Because the glass has a low SO.sub.3 content
and/or the limited region of the glass in which any coloration
could occur, depending on the particular soda-lime-silica-lass
composition, SO.sub.3 in these surfaces essentially has little if
any material effect on the glass color or spectral properties, even
if the effect could be measured. More suitably, such an effect
should not amount to altering the dominant wavelength of the glass
more than 3 to 5 nanometers.
[0033] Iron polysulfides, such as FeSx, can also be present in the
glass composition in an amount up to 10 ppm. FeSx is a byproduct of
the melting process. It is believed that FeSx is formed at redox
ratios above 0.50.
[0034] In a typical float glass process, water (H.sub.2O) is added
to the glass batch during processing to prevent dusting and
segregation of the batch material. H.sub.2O can be added to the
batch in an amount ranging from 2 to 4 weight percent based on the
total batch weight. In the final glass composition, H.sub.2O can be
present in an amount ranging up to 1,000 ppm, for example, 200 to
600 ppm, or 300 to 500 ppm.
[0035] The amount of H.sub.2O in the final glass composition will
affect the infrared absorption characteristics of the glass. More
particularly, increasing the amount of H.sub.2O in the glass
composition will increase the infrared absorption. Flat glass
produced by a process that uses oxyfuel firing during melting
typically has a higher H.sub.2O content than glass produced using
conventional air-fuel firing. In an oxyfuel fired melting furnace,
oxygen is combined with natural gas and combusted to melt the glass
batch.
[0036] Glass made according to the present invention via the float
process typically has a thickness ranging from about 1 millimeter
to 10 millimeters.
[0037] The glass compositions according to the present invention
can be used to make glass for a variety of applications, such as
but not limited to, architectural applications, automotive
applications, marine applications, rail applications, etc. For
automotive applications, glass produced according to the present
invention typically has a thickness ranging from 0.071 to 0.197
inches (1.8 to 5 mm). Such glass can be used as automobile
sidelights, automobile rear windows, or at least one ply in a
multiple ply arrangement. For example, the ply can be used to make
an automobile windshield comprised of two annealed glass plies
which are laminated together using a polyvinyl butyral interlayer.
Depending on whether the glass will be used as an automobile side
light or rear window, the glass can be tempered, as is well known
in the art. In a multiple ply arrangement, at least a single piece
of the glass can be annealed as is well known in the art.
[0038] The spectral properties of glass can change after thermal
processing, such as bending and/or tempering, or prolonged exposure
to ultraviolet radiation, commonly referred to as solarization.
Consequently, various embodiments of the invention are initially
prepared to compensate for any losses attributable to tempering and
solarization. The result is a glass product having acceptable
performance properties.
EXAMPLES
[0039] The present invention is illustrated by the following
non-limiting examples. Tables 1 and 2 illustrate examples of glass
compositions which embody the principles of the present invention.
The examples in Table 1 represent computer models generated by a
glass color and spectral performance computer model developed by
PPG Industries, Inc. The examples in Table 2 are actual
experimental laboratory melts. To prepare the melts, the following
raw materials were mixed to produce a final glass weight of
approximately 700 grams:
3 cullet* 239.74 g sand 331.10 g soda ash 108.27 g limestone 28.14
g dolomite 79.80 g salt cake 2.32 g Fe.sub.2O.sub.3 (total iron) as
required CuO as required Nd.sub.2O.sub.3 as required
Co.sub.3O.sub.4 as required *The cullet used in the melts (which
formed approximately 30% of the melt) included up to 0.51 wt. %
total iron, 0.055 wt. % TiO.sub.2 and 7 ppm Cr.sub.2O.sub.3
[0040] Reducing agents were added to the mixture as required to
control redox. A portion of the raw batch material was then placed
in a silica crucible in a gas fired furnace and heated to
2450.degree. F. (1343.degree. C.). When the batch material melted,
the remaining raw materials were added to the crucible, and the
crucible was held at 2450.degree. F. (1343.degree. C.) for 30
minutes. The molten batch was then heated and held at 2500.degree.
F. (1371.degree. C.) for 30 minutes, 2550.degree. F. (1399.degree.
C.) for 30 minutes, and 2600.degree. F. (1427.degree. C.) for 1
hour. Next, the molten glass was fitted in water, dried and
reheated to 2650.degree. F. (1454.degree. C.) in a platinum-rhodium
crucible in an electric furnace for two hours. The molten glass was
then poured out of the crucible to form a slab and annealed.
Samples were cut from the slab, ground and polished for
analysis.
[0041] The chemical analysis of the glass compositions (except for
FeO, FeSx, and Nd.sub.2O.sub.3) was determined using a RIGAKU 3370
X-ray fluorescence spectrophotometer. The spectral characteristics
of the glass were determined on annealed samples using a
Perkin-Elmer Lambda 9 UVNIS/NIR spectrophotometer prior to
tempering the glass or prolonged exposure to ultraviolet radiation,
which will affect the spectral properties of the glass. The FeO and
FeSx content and redox were determined using the glass color and
spectral performance computer model developed by PPG Industries,
Inc. The content of Nd.sub.2O.sub.3 was based on actual batch
weight.
[0042] The following are approximate amounts of the basic oxides in
the experimental melts based on the batch composition:
4 SiO.sub.2 72.1 wt. % Na.sub.2O 13.6 wt. % CaO 8.8 wt. % MgO 3.8
wt. % Al.sub.2O.sub.3 0.18 wt. % K.sub.2O 0.057 wt. %
[0043] The spectral properties shown in Tables 1 and 2 are based on
a reference thickness of 0.154 inches (4.06 mm).
[0044] The following performance parameters--solar ultraviolet
transmittance (SAE Tuv), solar infrared transmittance (TSIR), solar
energy transmittance (SAE Tsol), visible (luminous) transmittance
(LTA), solar ultraviolet transmittance (ISO Tuv)--are discussed in
the Example section. The parameters were calculated as described
below:
[0045] LTA was calculated using CIE Standard Illuminant "A" with a
CIE 1931 Standard (2.degree.) Observer over the wavelength range of
380 to 770 nanometers.
[0046] ISO Tuv was calculated according to ISO 9050 (1990-02-15)
over the range of 280 to 380 nanometers.
[0047] SAE Tuv was calculated according to SAE J1796 (1995-05) over
the wavelength range of 300 to 400 nanometers.
[0048] TSIR was calculated over the wavelength range of 775 to 2125
nanometers using the Parry Moon air mass 2.0 d solar energy
distribution at 50 nanometer intervals using the Trapezoidal Rule
of integration.
[0049] SAE Tsol was calculated according to SAE J1796 (1995-05)
over the wavelength range of 300 to 2500 nanometers.
[0050] Glass color in terms of dominant wavelength (DW) and
excitation purity (Pe), was calculated using CIE Standard
Illuminant "C" with a 1931 Standard (2.degree.) Observer, following
the procedures established in ASTM E308-90. Color coordinates L*,
a*, b* (CIELAB) were calculated using CIE 1964 Standard
(10.degree.) Observer over the wavelength range of 380 to 770
nanometers and CIE Standard Illuminant D65 according to the
procedures established in ASTM E 308-90.
5TABLE 1 Data for Modeled Examples Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5
Ex. 6 Component Total Iron (wt %) 0.500 0.575 0.550 0.500 0.475
0.425 Redox Ratio 0.375 0.375 0.425 0.383 0.383 0.383 CoO wt (%)
0.0015 0.0010 0.0008 0.0005 0.0008 0.0008 Cr2O3 (wt %) 0.0007
0.0007 0.0007 0.0005 0.0005 0.0005 MnO2 wt (%) 0.0020 0.0020 0.0020
CeO2 (wt %) TiO2 (wt %) 0.025 0.025 0.025 0.027 0.027 0.027 Nd2O3
(wt %) 0.2500 0.2000 0.2000 CuO (wt %) 0.1091 0.1091 0.1091 0.1100
0.2000 0.3500 FeS(x) (wt %) 0.00003 0.00003 0.00003 0.00007 0.00007
Performance Data LTA (%) 72.41 71.88 71.62 71.81 71.55 71.62 ISO
Tuv (%) 35.20 32.75 35.32 35.58 36.20 37.37 SAE Tuv (%) 51.81 49.30
51.93 52.16 52.74 53.88 SAE Tsol (%) 50.17 47.37 46.19 49.67 50.13
51.46 TSIR (%) 28.28 23.95 21.54 27.19 28.38 30.94 Color Data DW
(nm) 487.76 488.75 487.98 487.24 487.10 486.93 Pe (%) 7.16 7.21
8.08 7.60 7.91 8.22 D65/10 L* 89.40 89.21 89.19 89.22 89.12 89.21
a* -7.04 -7.82 -8.11 -7.39 -7.51 -7.68 b* -4.05 -3.60 -4.45 -4.42
-4.69 -4.96 Ex. 7 Ex. 8 Ex. 9 Ex. 10 Ex. 11 Component Total Iron
(wt %) 0.425 0.375 0.285 0.375 0.325 Redox Ratio 0.375 0.375 0.375
0.383 0.400 CoO wt (%) 0.0020 0.0021 0.0022 0.0014 0.0017 Cr2O3 (wt
%) 0.0075 0.0100 0.0150 0.0100 0.0150 MnO2 wt (%) 0.0020 0.0020
0.0020 CeO2 (wt %) TiO2 (wt %) 0.025 0.025 0.025 0.027 0.027 Nd2O3
(wt %) 0.125 0.150 CuO (wt %) 0.1100 0.2500 0.3500 0.2500 0.1100
FeS(x) (wt %) 0.00003 0.00003 0.00003 0.00007 0.00007 Performance
Data LTA (%) 71.75 71.21 71.48 71.27 71.33 ISO Tuv (%) 37.95 39.41
43.23 39.96 43.29 SAE Tuv (%) 54.40 55.75 59.17 56.09 59.06 SAE
Tsol (%) 52.60 53.82 57.62 53.46 55.78 TSIR (%) 33.45 36.44 43.88
35.53 39.59 Color Data DW (nm) 488.62 488.84 489.80 489.11 489.77
Pe (%) 6.70 6.99 6.52 6.87 6.13 D65/10 L* 89.02 88.81 88.89 88.86
88.77 a* -7.06 -7.48 -7.56 -7.70 -7.23 b* -3.49 -3.55 -2.96 -3.31
-2.73
[0051]
6TABLE 2 Data for Experimental Melts Ex. 12 Ex. 13 Ex. 14 Ex. 15
Ex. 16 Component Total Iron (wt %) 0.375 0.423 0.428 0.429 0.612
Redox Ratio 0.400 0.352 0.455 0.505 0.383 CoO (wt %) 0.0012 Cr2O3
(wt %) 0.0075 0.0008 0.0007 0.0005 0.0005 MnO2 (wt %) 0.0019 0.0018
0.0020 CeO2 (wt %) TiO2 (wt %) 0.027 0.026 0.027 0.027 0.027 Nd2O3
(wt %) 0.250 0.250 CuO (wt %) 0.1100 0.1078 0.1084 0.1091 FeS(x)
(wt %) 0.00007 Performance Data LTA (%) 71.51 79.85 78.23 77.13
71.79 ISO Tuv (%) 40.76 36.77 39.40 40.91 30.83 SAE Tuv (%) 56.98
53.80 56.45 57.81 48.15 SAE Tsol (%) 53.74 56.58 52.27 50.06 46.97
TSIR (%) 34.87 34.98 27.51 23.98 22.60 Color Data DW (nm) 487.51
491.90 489.57 488.88 488.42 Pe (%) 7.13 3.88 5.74 6.67 7.51 D65/10
L* 88.98 92.43 91.98 91.61 89.25 a* -7.01 -5.71 -6.87 -7.46 -8.17
b* -4.10 -1.06 -2.60 -3.35 -3.85 Ex. 17 Ex. 18 Ex. 19 Ex. 20 Ex. 21
Component Total Iron (wt %) 0.514 0.511 0.571 0.572 0.571 Redox
Ratio 0.389 0.414 0.350 0.340 0.358 CoO (wt %) 0.0015 0.0014 Cr2O3
(wt %) 0.0006 0.0006 0.0007 0.0005 0.0005 MnO2 (wt %) CeO2 (wt %)
TiO2 (wt %) 0.003 0.025 0.032 0.032 0.032 Nd2O3 (wt %) 0.075 0.075
0.250 0.220 0.250 CuO (wt %) 0.1687 0.1672 0.1680 FeS(x) (wt %)
Performance Data LTA (%) 72.21 72.26 72.47 72.33 72.13 ISO Tuv (%)
35.54 35.89 26.53 27.06 27.14 SAE Tuv (%) 52.94 53.32 43.04 43.59
43.64 SAE Tsol (%) 49.71 48.82 48.27 48.07 47.63 TSIR (%) 26.66
24.93 25.37 25.02 24.27 Color Data DW (nm) 486.79 486.85 490.25
490.05 489.95 Pe (%) 7.84 8.19 6.25 6.40 6.53 D65/10 L* 89.39 89.47
89.44 89.39 89.31 a* -7.03 -7.41 -8.14 -8.17 -8.27 b* -4.90 -5.08
-2.34 -2.50 -2.60
CONCLUSIONS
[0052] As illustrated by the examples above, glass compositions
having certain properties can be produced according to the present
invention. For example, glass melts produced according to the
present invention can yield a 0.154 inch. thick glass article
having an LTA of at least 70%; an ISO Tuv no more than 40.9%; an
SAE Tuv no more than 57.8%; an SAE Tsol. of no more than 56.6%; and
a TSIR of no more than 35%. The color of a 0.154 inches thick piece
of glass according to the present invention can be characterized by
a dominant wavelength (DW) between 486.8 and 491.9 nanometers and
an excitation purity between 3.9% and 8.2%.
[0053] For example, computer models show 0.154 inch thick glass can
be made having an LTA of at least 70%; an ISO Tuv no more than
43.3%; an SAE Tuv no more than 59.2%; an SAE Tsol of no more than
57.6%; and a TSIR of no more than 43.9%. The color of a 0.154
inches thick piece of glass according to the present invention can
be characterized by a dominant wavelength (DW) between 486.9 and
489.8 nanometers and an excitation purity between 6.1% and
9.2%.
[0054] Based on the examples provided above, a 0.154 inch (4.06 mm)
thick glass article formed from the glass composition of the
present invention exhibits one or more of the following spectral
properties: an LTA of at least 70%, for example, at least 72%; (b)
an ISO Tuv of no greater than 45%, for example, no greater than 42%
or no greater than 40%; (c) an SAE Tuv no greater than 60%, for
example, no greater than 55% or no greater than 50%; (d) an SAE
Tsol no greater than 60%, for example, no greater than 55% or no
greater than 50%; and (e) a TSIR no greater than 45%, for example,.
no greater than 40% or no greater than 35%. In addition, the blue
colored glass of the present invention can be characterized by a
dominant wavelength of no greater than 500 nanometers, for example,
between 480 and 495 nanometers, or between 485 and 490 nanometers,
and an excitation purity no greater than 18%, for example, no
greater than 15% or no greater than 10%, at a glass thickness of
0.154 inches. The glass of the present invention can have a redox
ratio ranging from 0.15 to 0.65, for example, 0.25 to 0.50, or 0.30
to 0.40.
[0055] When the glass produced according to the present invention
is used in selected areas of a motor vehicle such as the windshield
or front door windows, US law requires the glass to have an LTA of
at least 70%. Other countries like Europe, Japan, and Australia
require an LTA of at least 75%.
[0056] It will be readily appreciated by those skilled in the art
that modifications can be made to the invention without departing
from the concepts disclosed in the foregoing description. Such
modifications are to be considered as included within the scope of
the invention. Accordingly, the particular embodiments described in
detail hereinabove are illustrative only and are not limiting as to
the scope of the invention, which is to be given the full breadth
of the appended claims and any and all equivalents thereof.
* * * * *