U.S. patent application number 09/746968 was filed with the patent office on 2001-09-27 for gray glass composition.
Invention is credited to Haskins, David R., Krumwiede, John F., Longobardo, Anthony V., Shelestak, Larry J..
Application Number | 20010025002 09/746968 |
Document ID | / |
Family ID | 22548510 |
Filed Date | 2001-09-27 |
United States Patent
Application |
20010025002 |
Kind Code |
A1 |
Krumwiede, John F. ; et
al. |
September 27, 2001 |
Gray glass composition
Abstract
The present invention provides a glass composition having a
neutral gray color and a luminous (visible) transmittance within a
range that allows the glass to be used as privacy glazing in a
vehicle. The glass of the present invention has a standard
soda-lime-silica flat glass base composition and uses iron, cobalt
and selenium, and optionally nickel, as the colorants. It has also
been found that a nickel-free, neutral gray colored glass with a
luminous transmittance (C.I.E. illuminant A) of up to 40% at a
thickness of 3.9 millimeters may be attained by using as colorants:
0.59 to 0.99 wt. % of the total glass Fe.sub.2O.sub.3 (total iron),
no greater than 0.30 wt. % FeO; 60 to 180 PPM CoO and 5 to 30 PPM
Se. It has been found that a nickel-bearing, neutral gray colored
glass with a luminous transmittance (C.I.E. illuminant A) of up to
but less than 40% at a thickness of 3.9 millimeters may be attained
by using as colorants: 0.35 to 1.1 wt. % of the total glass
Fe.sub.2O.sub.3 (total iron), no greater than 0.30 wt. % FeO; 60 to
180 PPM CoO; 1 to 30 PPM Se; and 25 to 550 PPM NiO.
Inventors: |
Krumwiede, John F.;
(Cheswick, PA) ; Longobardo, Anthony V.; (Butler,
PA) ; Shelestak, Larry J.; (Bairdford, PA) ;
Haskins, David R.; (Gibsonia, PA) |
Correspondence
Address: |
P P G INDUSTRIES, INC.
ONE P P G PLACE
39 SOUTH
PITTSBURGH
PA
15272
US
|
Family ID: |
22548510 |
Appl. No.: |
09/746968 |
Filed: |
December 22, 2000 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09746968 |
Dec 22, 2000 |
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08529039 |
Sep 15, 1995 |
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08529039 |
Sep 15, 1995 |
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08153733 |
Nov 16, 1993 |
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Current U.S.
Class: |
501/64 ;
501/70 |
Current CPC
Class: |
C03C 3/087 20130101;
C03C 4/02 20130101 |
Class at
Publication: |
501/64 ;
501/70 |
International
Class: |
C03C 003/087; C03C
003/095 |
Claims
We claim:
1. A neutral gray colored glass composition having a base glass
portion comprising:
10 SiO.sub.2 66 to 75 percent by weight Na.sub.2O 10 to 20 CaO 5 to
15 MgO 0 to 5 Al.sub.2O.sub.3 0 to 5 K.sub.2O 0 to 5
and a colorant portion consisting essentially of:
11 Fe.sub.2O.sub.3 (total iron) 0.6 to 0.935 percent by weight FeO
up to 0.30 CoO 60 to 180 PPM Se 5 to 30 PPM
the glass having a luminous transmittance of 20 to 39.28 percent at
a thickness of 3.9 millimeters.
2. The composition as in claim 1 wherein the Fe.sub.2O.sub.3
concentration is from 0.71 to 0.935 weight percent, the FeO
concentration is from 0.181 to 0.285 weight percent, the CoO
concentration is from 75 to 150 PPM and the Se concentration is
from 11 to 24 PPM.
3. The composition of claim 1 wherein the color of the glass is
characterized by dominant wavelengths in the range of 480 to 580
nanometers and an excitation purity of no higher than 8% at a
thickness of 3.9 millimeters.
4. The composition of claim 3 wherein the color of the glass is
characterized by dominant wavelengths in the range of 485 to 540
nanometers and an excitation purity of no higher than 3
percent.
5. The composition as in claim 1 further including additional
ultraviolet absorbing material.
6. The composition as in claim 5 wherein said ultraviolet absorbing
material is an oxide of a material selected from a group consisting
essentially of cerium, vanadium, titanium and molybdenum and
combination thereof in an amount up to 2.0 wt. % of the glass
composition.
7. The composition as in claim 6 wherein said TiO.sub.2 is in an
amount from 0.1 to 1.0 wt. %.
8. The composition as in claim 7 wherein said TiO.sub.2 is in an
amount from 0.2 to 0.5 wt. %.
9. A glass sheet made from the composition as recited in claim
1.
10. The glass sheet as in claim 9 wherein the sheet has a thickness
between 3 to 6 mm.
11. The glass sheet as in claim 9 wherein the color of the glass is
characterized by dominant wavelengths in the range of 480 to 580
nanometers and an excitation purity of no higher than 8% at a
thickness of 3.9 millimeters.
12. The glass sheet as in claim 11 wherein the color of the glass
is characterized by dominant wavelengths in the range of 485 to 540
nanometers and an excitation purity of no higher than 3
percent.
13. A neutral gray colored glass composition having a base glass
portion comprising:
12 SiO.sub.2 66 to 75 percent by weight Na.sub.2O 10 to 20 CaO 5 to
15 MgO 0 to 5 Al.sub.2O.sub.3 0 to 5 K.sub.2O 0 to 5
and a colorant portion consisting essentially of:
13 Fe.sub.2O.sub.3 (total iron) 0.6 to 1.1 percent by weight FeO up
to 0.30 CoO 60 to 180 PPM Se 10 to 30 PPM NiO 25 to 550 PPM
the glass having a luminous transmittance of 20 to 44.5 percent at
a thickness of 3.9 millimeters.
14. The composition as in claim 13 wherein the Fe.sub.2O.sub.3
concentration is from 0.71 to 0.94 weight percent, the FeO
concentration is from 0.181 to 0.24 weight percent, the CoO
concentration is from 98 to 150 PPM and the Se concentration is
from 14 to 24 PPM and the NiO concentration is at least 50 PPM.
15. The composition of claim 13 wherein the color of the glass is
characterized by dominant wavelengths in the range of 502 to 580
nanometers and an excitation purity of no higher than 8% at a
thickness of 3.9 millimeters.
16. The composition of claim 15 wherein the color of the glass is
characterized by dominant wavelengths in the range of 502 to 540
nanometers and an excitation purity of no higher than 3
percent.
17. The composition as in claim 13 further including additional
ultraviolet absorbing material.
18. The composition as in claim 17 wherein said ultraviolet
absorbing material is an oxide of a material selected from a group
consisting essentially of cerium, vanadium, titanium and molybdenum
and combination thereof in an amount up to 2.0 wt. % of the glass
composition.
19. The composition as in claim 1 8 wherein said TiO.sub.2 is in an
amount from 0.1 to 1.0 wt. %.
20. The composition as in claim 19 wherein said TiO.sub.2 is in an
amount from 0.2 to 0.5 wt. %.
21. A glass sheet made from the composition as recited in claim
13.
22. The glass sheet as in claim 21 wherein the sheet has a
thickness between 3 to 6 mm.
23. The glass sheet as in claim 21 wherein the color of the glass
is characterized by dominant wavelengths in the range of 502 to 580
nanometers and an excitation purity of no higher than 8% at a
thickness of 3.9 millimeters.
24. The glass sheet as in claim 23 wherein the color of the glass
is characterized by dominant wavelengths in the range of 502 to 540
nanometers and an excitation purity of no higher than 3
percent.
25. A neutral gray colored glass composition having a base glass
portion comprising:
14 SiO.sub.2 66 to 75 percent by weight Na.sub.2O 10 to 20 CaO 5 to
15 MgO 0 to 5 Al.sub.2O.sub.3 0 to 5 K.sub.2O 0 to 5
and a colorant portion consisting essentially of:
15 Fe.sub.2O.sub.3 (total iron) 0.59 to 0.99 percent by weight FeO
up to 0.30 CoO 60 to 180 PPM Se 5 to 30 PPM
the glass having a luminous transmittance of up to 40 percent at a
thickness of 3.9 millimeters.
26. The composition as in claim 25 wherein the Fe.sub.2O.sub.3
concentration is from 0.75 to 0.86 weight percent, the FeO
concentration is from 0.18 to 0.25 weight percent, the CoO
concentration is from 108 to 114 PPM and the Se concentration is
from 13 to 24 PPM.
27. The composition of claim 26 wherein the color of the glass is
characterized by dominant wavelengths in the range of 485 to 560
nanometers and the corresponding complementary wavelengths and an
excitation purity of no higher than 8% at a thickness of 3.9
millimeters.
28. The composition of claim 27 wherein the glass is characterized
by an excitation purity of no higher than 3 percent.
29. A neutral gray colored glass composition having a base glass
portion comprising:
16 SiO.sub.2 66 to 75 percent by weight Na.sub.2O 10 to 20 CaO 5 to
15 MgO 0 to 5 Al.sub.2O.sub.3 0 to 5 K.sub.2O 0 to 5
and a colorant portion consisting essentially of:
17 Fe.sub.2O.sub.3 (total iron) 0.35 to 1.1 percent by weight FeO
up to 0.30 CoO 60 to 180 PPM Se 1 to 30 PPM NiO 25 to 550 PPM
the glass having a luminous transmittance of less than 45 percent
at a thickness of 3.9 millimeters.
30. The composition of claim 29 wherein the color of the glass is
characterized by dominant wavelengths in the range of 485 to 560
nanometers and the corresponding complementary wavelengths and an
excitation purity of no higher than 8% at a thickness of 3.9
millimeters.
31. The composition of claim 30 wherein the glass is characterized
by an excitation purity of no higher than 3 percent.
Description
[0001] This is a continuation in part application of U.S. patent
application Ser. No. 08/153,733, filed Nov. 16, 1993.
BACKGROUND OF THE INVENTION
[0002] This invention involves a neutral gray colored glass that
has a luminous transmittance that makes it highly desirable for use
as privacy glazing in vehicles, e.g. in the rear portions of vans.
In particular, the glass of the present invention has a luminous
transmittance range of up to 45 percent. The desired color and
performance is attained by using iron, cobalt, selenium and/or
nickel as colorants. In addition, the glass of the present
invention generally exhibits lower infrared and total solar energy
transmittance than typical green glasses used in automotive
applications to reduce heat gain in the interior of the enclosure.
The glass is also compatible with flat glass manufacturing
methods.
[0003] Various heat-absorbing glass substrates are known in the
art. The primary colorant in typical green tinted automotive
glasses is iron, which is usually present in both the
Fe.sub.2O.sub.3 and FeO forms. As is conventional, the total amount
of iron present in a glass is expressed herein as Fe.sub.2O.sub.3,
regardless of the form actually present. Typical green tinted
automotive glass has about 0.5 percent by weight total iron with
the ratio of FeO to total iron being about 0.25.
[0004] Some glasses, e.g. U.S. Reissue Pat. No. 25,312 to Duncan et
al. and U.S. Pat. No. 4,339,541 to Dela Ruye, produce a gray color
in the glass by including nickel oxide, cobalt oxide and selenium
as colorants. However, inclusion of nickel-containing materials
must be carefully controlled because the presence of nickel during
the melting process sometimes leads to the formation of nickel
sulfide stones in the glass. Additional potential problems faced
when using nickel include haze formation on the glass surface due
to reduction of the nickel in the tin bath and change in the glass
color when it is heat treated.
[0005] To avoid this problem, nickel-free colored glasses
containing iron oxide, cobalt oxide, and selenium were developed,
as disclosed in U.S. Pat. No. 3,296,004 to Duncan et al., U.S. Pat.
No. 3,723,142 to Kato et al. and British Pat. Specification
1,331,492 to Bamford. In U.S. Pat. No. 4,104,076 to Pons, instead
of nickel, Cr.sub.2O.sub.3 or UO.sub.2 are used in combination with
iron oxide, cobalt oxide, and selenium to produce gray glass. More
recent nickel-free gray glasses are disclosed in U.S. Pat. Nos.
5,023,210 to Krumwiede et al. and 5,278,108 to Cheng et al. and EP
536 049 to Alvarez-Casariego, et al., which use iron oxide, cobalt
oxide and selenium, as colorants. Krumwiede et al. and
Alvarez-Casariego et al. further disclose that chromic oxide may be
used as an additional colorant.
[0006] Many of the commercially available gray glasses are too dark
to be used in the forward vision area of a vehicle. In addition,
the glasses may also be too dark to allow safety lighting mounted
in the interior of the vehicle from being seen from the exterior of
the vehicle. It would be desirable to have a neutral gray glass
that provides a dark gray color for use in privacy areas of a
vehicle while allowing adequate safety lighting illumination and
have a consistent color and further that is compatible with
commercial flat glass manufacturing techniques.
SUMMARY OF THE INVENTION
[0007] The present invention provides a glass composition having a
neutral gray color and a luminous (visible) transmittance within a
range that allows the glass to be used as privacy glazing in a
vehicle. The glass of the present invention has a standard
soda-lime-silica flat glass base composition and uses iron, cobalt
and selenium, and optionally nickel, as the colorants. It has been
found that a nickel-free, neutral gray colored glass with a
luminous transmittance (C.I.E. illuminant A) of up to 40% at a
thickness of 3.9 millimeters may be attained by using as colorants:
0.59 to 0.99 wt. % of the total glass Fe.sub.2O.sub.3 (total iron),
no greater than 0.30 wt. % FeO; 60 to 180 PPM CoO and 5 to 30 PPM
Se. In one embodiment, the glass composition includes 0.75 to 0.86
wt. % Fe.sub.2O.sub.3; 0.18 to 0.25 wt. % FeO; 108 to 144 PPM CoO
and 13 to 24 PPM Se. It has been found that a nickel-bearing,
neutral gray colored glass with a luminous transmittance (C.I.E.
illuminant A) of up to but less than 45% at a thickness of 3.9
millimeters may be attained by using as colorants: 0.35 to 1.1 wt.
% of the total glass Fe.sub.2O.sub.3 (total iron), no greater than
0.30 wt. % FeO; 60 to 180 PPM CoO; 1 to 30 PPM Se; and 25 to 550
PPM NiO. In one embodiment, the glass composition includes 0.71 to
0.94 wt. % Fe.sub.2O.sub.3, 0.181 to 0.24 wt. % FeO, 98 to 150 PPM
CoO, 14 to 24 PPM Se, and a minimum of 50 PPM NiO.
[0008] The dominant wavelength of the glasses in the present
invention may vary somewhat in accordance with particular color
preferences. In the present invention, it is preferred that the
glass be a neutral gray color characterized by dominant wavelengths
in the range of 480 to 580 nanometers, preferably 485 to 560
nanometers, with an excitation purity of no higher than 8%,
preferably no higher than 3%.
DETAILED DESCRIPTION
[0009] The base glass of the present invention, that is, the major
constituents of the glass without colorants, is commercial
soda-lime-silica glass characterized as follows:
1 Weight % 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 K.sub.2O 0 to 5 BaO 0 to 1
[0010] To this base glass, the present invention adds colorants in
the form of iron, cobalt, selenium and/or nickel. In one particular
embodiment of the invention, the glass is essentially nickel-free;
that is, no deliberate addition of nickel or nickel compounds is
made, although the possibility of traces of nickel due to
contamination may not always be avoided. The glass in the present
invention is essentially free of other colorants, such as, but are
not limited to chromium, manganese, cerium, molybdenum, titanium,
chlorine, zinc, zirconium, sulfur, fluorine, lithium and strontium.
In particular, the glass composition taught herein does not include
chromium as a colorant as does several of the gray colored glasses
in the prior art. It has been found the inclusion of chromium tends
to reduce the luminous transmittance and total solar energy
transmittance and increase the dominant wavelength of the glass. It
should be appreciated that the glass compositions disclosed herein
may include small amounts of the materials identified above, for
example as melting and refining aids, tramp materials or
impurities. It should be further appreciated that some of these
materials as well as others may be added to the glass to improve
the solar performance of the glass as will be discussed later in
more detail.
[0011] The selenium colorant contributes a pink color to the glass
as well as a brown color when complexed with iron to form iron
selenide (FeSe). Cobalt produces a blue color. Iron contributes
yellow and blue in varying proportions depending upon the oxidation
state. Nickel, if used, contributes a green-brown to yellow-brown
color.
[0012] The glass of the present invention may be melted and refined
in a continuous, large-scale, commercial melting operation and
formed into flat glass sheets of varying thicknesses by the float
method in which the molten glass is supported on a pool of molten
metal, usually tin, as it assumes a ribbon shape and is cooled. It
should be appreciated that as a result of forming the glass on
molten tin, measurable amounts of tin oxide may migrate into
surface portions of the glass on the side that was in contact with
the tin. Typically, a piece of float glass has an SnO.sub.2
concentration of at least 0.05 wt. % in the first few microns below
the surface of the glass that was in contact with the tin.
[0013] The total amount of iron present in the glass is expressed
herein in terms of Fe.sub.2O.sub.3 in accordance with standard
analytical practice, but that does not imply that all of the iron
is actually in the form of Fe.sub.2O.sub.3. Likewise, the amount of
iron in the ferrous state is reported as FeO, even though it may
not actually be present in the glass as FeO. The proportion of the
total iron in the ferrous state is used as a measure of the redox
state of the glass and is expressed as the ratio
FeO/Fe.sub.2O.sub.3, which is the weight percent of iron in the
ferrous state (expressed as FeO) divided by the weight percent of
total iron (expressed as Fe.sub.2O.sub.3). Unless stated otherwise,
the term Fe.sub.2O.sub.3 in this specification shall mean total
iron expressed in terms of Fe.sub.2O.sub.3 and the term FeO shall
mean iron in the ferrous state expressed in terms of FeO.
[0014] The glass compositions disclosed in the present invention
may be made using any of several types of melting arrangements,
such as but not limited to, a conventional, overhead fired
continuous melting operation as is well known in the art or a
multi-stage melting operation, of the type that is discussed later
in more detail. However, for glass compositions having a redox of
less than 0.30, the former operation is preferred and for glass
compositions having a redox of 0.30 or greater, the latter
operation is preferred.
[0015] Conventional, overhead fired continuous melting operations
are characterized by depositing batch material onto a pool of
molten glass maintained within a tank type melting furnace and
applying thermal energy until the materials are melted into the
pool of molten glass. The melting tanks conventionally contain a
large volume of molten glass so as to provide sufficient residence
time for currents in the molten glass to affect some degree of
homogenization and fining before the glass is discharged into a
forming operation.
[0016] The multi-stage glass melting and refining operation
disclosed in U.S. Pat. Nos. 4,381,934 to Kunkle et al.; 4,792,536
to Pecoraro et al.; and 4,886,539 to Cerutti et al. is
characterized by separate stages whereby more flexibility in
controlling redox conditions is provided. The overall melting
process disclosed in these patents consists of three stages: a
liquefaction stage, a dissolving stage, and a vacuum refining
stage. In the liquefaction stage, batch materials, preferably in a
pulverulent state, are fed into a rotating, drum-shaped liquefying
vessel. As batch material is exposed to the heat within the vessel,
liquefied material flows down a sloped batch material lining to a
central drain opening at the bottom of the vessel. A stream of
liquefied material falls freely from the liquefaction vessel into a
dissolving vessel for the dissolving stage. The dissolving vessel
completes the dissolution of unmelted particles in the liquefied
material coming from the liquefaction stage by providing residence
time at a location isolated from the downstream refining stage. The
dissolving vessel may be in the form of a horizontally elongated
refractory basin with the inlet and outlet at opposite ends thereof
so as to assure adequate residence time. The refining stage
preferably consists of a vertically upright vessel that may be
generally cylindrical in configuration having an interior ceramic
refractory lining shrouded in a gas-tight, water-cooled casing. As
the molten material enters the vessel from the dissolving vessel,
it encounters a reduced pressure within the refining vessel. Gases
included in the melt expand in volume, creating a foam. As foam
collapses, it is incorporated into the liquid body held in the
refining vessel. Refined molten material is drained from the bottom
of the refining vessel into a receiving chamber and delivered to a
float forming chamber.
[0017] A stirring arrangement may be employed in the multi-stage
process to homogenize the glass after it has been refined in order
to produce glass of the highest optical quality. If desired, a
stirring arrangement may be integrated with a float forming
chamber, whereby the glass in the stirring chamber rests on a layer
of molten metal. The molten metal may be continuous with the molten
metal constituting the support in the forming chamber, and is
usually comprised essentially of tin.
[0018] The multi-stage operation discussed above generally operates
at a redox level of 0.30 or higher; however, redox levels below
0.30 may be achieved by increasing the amount of oxidizing
constituents in the glass batch. For example, manganese oxide may
be added to lower the redox level. Redox may also be controlled by
adjusting the gas/O.sub.2 ratio of the burners.
[0019] The transmittance data provided throughout this disclosure
is based on a glass thickness of 3.9 millimeters (0.154 inch).
Luminous transmittance (LT.sub.A) is measured using C.I.E. 1931
standard illuminant "A" over the wavelength range 380 to 770
nanometers at 10 nanometer intervals. Total solar ultraviolet
transmittance (TSUV) is measured over the wavelength range 295 to
395 nanometers at 10 nanometer intervals. Total solar infrared
transmittance (TSIR) is measured over the wavelength range 775 to
2125 nanometers at 50 nanometer intervals. Total solar energy
transmittance (TSET) represents a computed value based on measured
transmittances from 275 to 2125 nanometers at 50 nanometer
intervals. All solar transmittance data is calculated using Parry
Moon air mass 2.0 solar data. Glass color in terms of dominant
wavelength and excitation purity are measured using C.I.E. 1931
standard illuminant "C" with a 2.degree. observer.
[0020] To determine this transmittance data, the transmittance
values are integrated over the wavelength range [a,b]. This range
is divided into n equal subintervals of length h by points
{X.sub.0, X.sub.1, . . . , X.sub.n} where X.sub.i=a+(i.times.h). In
the present disclosure, the Rectangular Rule is used to compute the
transmittance data. An interpolating function is used to
approximate the integrand .function. in each subinterval. The sum
of integrals of this function provides an approximation of the
integral: 1 l = a b f ( X ) X
[0021] In the case of the Rectangular Rule, a constant value
.function.(X.sub.i) is used as an approximation of .function.(X) on
[X.sub.i-1, X.sub.i]. This yields a step-function approximation of
.function.(X) on [a,b], and the numerical integration formula: 2 l
= l = 1 n f ( X i ) .times. h
[0022] Tables 1 and 2 illustrate examples of glass compositions at
a 3.9 mm (0.154 in.) reference thickness which embody the
principles of the present invention. Only the colorant portions of
the examples are listed in the table below, with Fe.sub.2O.sub.3
being total iron, including that present as FeO.
[0023] The information provided in Examples 1 to 29 of Table 1 and
Examples 41 to 68 of Table 2 are based on a computer model that
generates theoretical spectral properties based on the glass
compositions. The compositions in Table 1 exclude nickel oxide as a
colorant while the compositions in Table 2 include nickel oxide as
a colorant. In addition, the information provided in Examples 30 to
33 in Table 1 is based on experimental laboratory melts and the
information for Examples 34 to 40 of Table 1 is based on actual
glass produced using the multi-stage melting process discussed
earlier. However, under certain conditions, it may be preferred
that the glasses disclosed in the present invention be made using a
conventional, overhead fired continuous melting process as
discussed earlier.
[0024] It should be noted that Examples 1 to 29 in Table 1 were
modeled to include up to 1 PPM NiO; 6 to 13 PPM of Cr.sub.2O.sub.3
and up to 46 PPM MnO.sub.2, each of which are considered to be
tramp and/or residual levels of these materials, to better reflect
the expected spectral properties of the glass. The analysis of
Examples 30 to 33 in Table 1 showed less than 3 PPM NiO and from 6
to 13 PPM Cr.sub.2O.sub.3 and the analysis of Examples 34 to 40
showed less than 3 PPM NiO and between 5 to 9 PPM Cr.sub.2O.sub.3.
In addition, the analyses showed that Examples 35, 37, 38 and 40
included 30 up to 46 PPM MnO.sub.2 and Examples 34, 36, and 39
included 566 PPM; 940 PPM and 1208 PPM MnO.sub.2, respectively.
Manganese was added to these later glass compositions to control
redox in a manner as discussed earlier. It is believed that the
level of MnO.sub.2 in Examples 34, 36 and 39 will slightly lower
LTA, TSUV and TSET and may operate as a weak colorant imparting a
yellow/green color component in the glass. The modeled compositions
in Table 2 included up to 13 PPM Cr.sub.2O.sub.3.
[0025] The representative base glass composition for the examples
is as follows:
2 SiO.sub.2 71 to 75% by weight Na.sub.2O 13 to 14 CaO 8 to 9 MgO 3
to 4 Al.sub.2O.sub.3 0.1 to 0.7
[0026] It should be appreciated that this composition may vary
especially as a result of the actual amount of colorant present in
the glass composition.
3 TABLE 1A 1 2 3 4 5 6 7 8 9 10 Fe.sub.2O.sub.3 wt. % 0.59 0.59
0.59 0.60 0.60 0.60 0.65 0.65 0.65 0.70 FeO wt. % 0.156 0.156 0.156
0.159 0.159 0.153 0.172 0.172 0.172 0.185 Redox 0.265 0.265 0.265
0.265 0.265 0.255 0.265 0.265 0.265 0.265 CoO PPM 140 155 80 127
150 65 179 80 116 179 Se PPM 22 11 29 22 12 9 13 29 19 19 LT.sub.A
34.23 38.13 38.61 35.77 38.12 52.43 33.46 37.97 38.31 30.20 TSIR
34.77 35.05 34.68 34.26 34.49 34.99 31.84 31.59 31.79 29.32 TSUV
24.36 30.24 21.35 24.13 29.34 26.05 27.16 20.00 24.29 22.86 TSET
36.06 39.02 36.80 36.29 38.53 43.48 35.24 34.80 36.05 31.87 DW nm
549.3c 478.3 585.0 496.1c 478.2 524.4 477.6 584.1 504.2c 475.1 Pe %
2.48 12.48 14.75 1.51 10.91 1.13 14.14 14.9 0.71 9.0
[0027]
4 TABLE 1B 11 12 13 14 15 16 17 18 19 20 Fe.sub.2O.sub.3 wt. % 0.70
0.70 0.71 0.710 0.75 0.80 0.82 0.82 0.82 0.845 FeO wt. % 0.185
0.185 0.181 0.181 0.198 0.212 0.205 0209 0.209 0.211 Redox 0.265
0.265 0.255 0.255 0.265 0.265 0.25 0.255 0.255 0.25 CoO PPM 135 150
98 75 130 120 120 124 100 124 Se PPM 21 10 17 14 15 18 18 16 20 19
LT.sub.A 34.30 38.24 43.63 48.81 37.59 36.78 36.39 39.28 40.42
35.43 TSIR 29.34 29.59 29.44 29.53 27.31 25.25 26.75 24.89 24.85
25.80 TSUV 22.08 27.43 20.72 21.85 23.62 21.15 18.78 18.30 17.14
18.08 TSET 33.04 35.96 36.51 38.60 33.65 31.75 32.26 32.38 32.32
31.31 DW nm 559.7c 480.0 562.5 563.0 481.1 486.2 552.0 495.0 569.1
550.4 Pe 1.39 12.48 2.7 3.88 5.25 1.11 0.52 2.39 5.41 0.51
[0028]
5 TABLE 1C 21 22 23 24 25 26 27 28 29 30 Fe.sub.2O.sub.3 wt. % 0.85
0.90 0.935 0.95 0.98 0.98 0.98 0.99 1.10 0.818 FeO wt. % 0.225
0.238 0.261 0.251 0.259 0.259 0.259 0.262 0.281 0.245 Redox 0.265
0.265 0.279 0.265 0.265 0.265 0.265 0.265 0.255 0.300 CoO PPM 100
140 148 110 179 179 115 127 124 126 Se PPM 23 24 23 20 29 11 17 18
20 18 LT.sub.A 36.29 30.56 27.95 35.55 24.20 31.59 36.18 34.07
34.43 32.68 TSIR 23.32 21.56 18.09 20.09 18.98 19.28 19.24 18.93
16.35 19.66 TSUV 18.22 16.90 13.21 17.46 14.05 20.12 17.98 17.42
12.17 20.86 TSET 29.88 26.81 23.58 27.94 22.71 27.21 27.94 26.94
24.95 26.75 DW nm 579.4 584.8 500.3 569.5 518.6c 481.1 498.4 491.2
551.0 488.8 Pe 6.95 1.38 0.97 2.98 1.23 15.35 1.34 2.07 3.67
2.79
[0029]
6 TABLE 1D 31 32 33 34 35 36 37 38 39 40 Fe.sub.2O.sub.3 wt. %
0.826 0.93 0.935 0.657 0.803 0.811 0.816 0.817 0.822 0.825 FeO wt.
% 0.257 0.257 0.261 0.190 0.212 0.212 0.186 0.215 0.216 0.236 Redox
0.313 0.276 0.279 0.289 0.264 0.261 0.228 0.264 0.263 0.286 CoO PPM
105 120 128 66 118 120 121 124 124 124 Se PPM 17 19 19 11 18 17 20
18 16 19 LT.sub.A 35.83 31.95 31.19 51.83 36.15 36.56 36.38 35.93
36.13 33.84 TSIR 18.75 18.40 18.07 32.59 24.84 25.99 29.36 24.52
25.11 21.21 TSUV 21.89 16.59 17.35 32.55 22.91 22.19 21.07 22.35
22.24 21.82 TSET 27.56 25.52 25.17 42.46 31.47 32.30 33.96 31.30
31.74 28.43 DW nm 497.6 515.6 496.4 510.2 492.7 490.7 556.1 488.0
487.1 494.5 Pe 1.56 1.05 1.71 0.67 0.91 1.36 0.20 1.56 2.52
0.92
[0030]
7 TABLE 2A 41 42 43 44 45 46 47 48 49 Fe.sub.2O.sub.3 wt. % 0.40
0.45 0.50 0.50 0.51 0.51 0.52 0.55 0.60 FeO wt. % 0.102 0.119 0.130
0.128 0.135 0.135 0.138 0.146 0.153 Redox 0.255 0.265 0.265 0.255
0.265 0.265 0.265 0.265 0.255 CoO PPM 102 110 135 100 115 100 179
95 110 Se PPM 6 11 12 8 12 1 15 4 10 NiO PPM 400 250 350 200 250
350 500 450 200 LT.sub.A 42.21 39.78 33.25 45.52 37.88 44.16 24.68
39.97 41.74 TSIR 46.29 42.82 39.15 40.24 38.92 38.97 37.28 36.21
34.40 TSUV 36.94 35.13 32.27 31.41 32.14 39.83 29.36 35.73 26.55
TSET 45.87 43.13 38.39 43.91 40.13 43.47 33.72 39.66 38.95 DW nm
558.8 547.0 524.8 505.5 553.6 491.1 520.9 548.1 515.8 Pe % 3.55
0.53 0.45 1.34 0.81 4.86 0.26 3.06 1.29
[0031]
8 TABLE 2B 50 51 52 53 54 55 56 57 58 Fe.sub.2O.sub.3 wt. % 0.60
0.65 0.70 0.71 0.71 0.75 0.80 0.82 0.82 FeO wt. % 0.153 0.172 0.185
0.181 0.181 0.198 0.212 0.209 0.209 Redox 0.255 0.265 0.265 0.255
0.255 0.265 0.265 0.255 0.255 CoO PPM 102 105 125 98 98 90 90 124
124 Se PPM 12 8 11 14 14 2 2 18 20 NiO PPM 100 250 300 100 50 450
500 200 150 LT.sub.A 44.50 40.06 34.15 42.58 43.92 39.70 37.97
33.86 34.07 TSIR 36.67 31.41 28.85 29.25 29.38 26.64 24.59 24.44
24.51 TSUV 25.84 29.86 26.54 21.68 21.74 29.99 28.40 17.49 16.96
TSET 40.17 36.98 32.95 36.03 36.72 34.09 32.10 29.55 29.62 DW nm
513.6 498.6 510.2 558.9 546.2 532.0 544.8 566.3 568.7 Pe % .97 1.92
1.12 3.37 1.91 3.06 4.52 6.16 6.2
[0032]
9 TABLE 2C 59 60 61 62 63 64 65 66 67 68 Fe.sub.2O.sub.3 wt. % 0.82
0.85 0.90 0.935 0.935 0.935 0.950 1.00 1.10 1.10 FeO wt. % 0.209
0.225 0.238 0.238 0.238 0.238 0.251 0.265 0.291 0.291 Redox 0.255
0.265 0.265 0.255 0.255 0.255 0.265 0.265 0.265 0.265 CoO PPM 124
135 140 170 160 150 130 110 160 100 Se PPM 20 12 15 19 19 19 10 5
12 8 NiO PPM 50 350 250 200 150 100 400 450 400 300 LT.sub.A 36.25
30.23 29.83 24.48 26.21 28.06 29.90 33.06 25.07 35.01 TSIR 24.72
22.82 21.27 20.36 20.25 20.55 19.58 18.20 15.62 15.84 TSUV 17.05
22.17 19.94 13.51 13.56 13.62 20.79 21.84 25.43 18.81 TSET 30.73
27.76 26.63 23.56 24.30 25.08 25.72 26.26 21.42 25.45 DW nm 562.6
532.9 517.1 502.6 505.4 509.2 535.9 530.5 503.4 536.8 Pe % 3.27
1.82 1.12 1.62 1.40 1.22 2.72 3.40 2.75 3.54
[0033] Referring to Tables 1 and 2, the present invention provides
a neutral gray colored glass using a standard soda-lime-silica
glass base composition and iron, cobalt and selenium, and
optionally nickel as colorants. Not all of the examples are the
same gray color as indicated by the dominant wavelengths (DW) and
excitation purities (Pe). In the present invention, it is preferred
that the glass be a neutral gray color characterized by dominant
wavelengths in the range of 480 to 580 nanometers, preferably 485
to 560 nanometers, with an excitation purity of no higher than 8%,
and preferably no higher than 3%. In addition, for both the
nickel-free and nickel-bearing compositions, glasses having a
dominant wavelength that is a complimentary wavelength within this
wavelength range may also provide the desired neutral color,
especially at an excitation purity of no higher than 3% and
preferably no higher than 1.5%, as shown in Examples 1, 4, 9, 11
and 23.
[0034] In the present invention, the colorants used to produce a
neutral, nickel-free gray colored glass with an LT.sub.A of up to
40% at a thickness of 3.9 millimeters includes 0.59 to 0.99 wt. %
of the total glass Fe.sub.2O.sub.3 (total iron), no greater than
0.30 wt. % FeO; 60 to 180 PPM CoO and 5 to 30 PPM Se and preferably
0.71 to 0.935 wt. % Fe.sub.2O.sub.3; 0.181 to 0.285 wt. % FeO; 75
to 150 PPM CoO and 11 to 24 PPM Se, and more preferably 0.75 to
0.86 wt. % Fe.sub.2O.sub.3; 0.18 to 0.25 wt. % FeO; 108 to 144 PPM
CoO and 13 to 24 PPM Se.
[0035] In the present invention, a nickel-bearing, neutral gray
colored glass with a luminous transmittance of up to but less than
45% at a thickness 25 of 3.9 millimeters may be attained by using
as colorants: 0.35 to 1.1 wt. % of the total glass Fe.sub.2O.sub.3
(total iron), no greater than 0.30 wt. % FeO; 60 to 180 PPM CoO; 1
to 30 PPM Se; and 25 to 550 PPM NiO, and preferably 0.71 to 0.94
wt. % Fe.sub.2O.sub.3; 0.181 to 0.24 wt. % FeO; 98 to 150 PPM CoO;
14 to 24 PPM Se, and a minimum of 50 PPM NiO.
[0036] The redox ratio for the glass of the present invention is
maintained between about 0.20 to 0.30, and preferably between 0.24
to 0.28 which is the typical operating range for a conventional
overhead fired melting operation. Higher redox levels may be
attained by processes disclosed herein, but the use of higher redox
ratios is preferably avoided to prevent excessive volatilization of
selenium during melting.
[0037] Glass made by the float process typically ranges from a
sheet thickness of about 1 millimeters to 10 millimeters. For the
vehicle glazing applications, it is preferred that the glass sheets
have a thickness within the thickness range of 1.8 to 6
millimeters.
[0038] If desired, ultraviolet radiation absorbing materials may be
added to the glass compositions of the present invention to improve
its solar performance. Although not limiting in the present
invention, a total of up to 2.0 wt. % of oxides of cerium,
vanadium, titanium and molybdenum and combinations thereof may be
used as UV absorbers to reduce the TSUV of the glass. In a
preferred embodiment of the invention, TiO.sub.2 is the preferred
UV absorber and may be added in an amount ranging from 0.1 to 1.0
wt. % of the glass composition, and more preferably 0.2 to 0.5 wt.
%. It should be appreciated that in sufficient quantities, the
cerium, vanadium, titanium and molybdenum may also operate as a
colorant in the glass composition, with the cerium and titanium
contributing a yellow component to the glass color, the vanadium
contributing a green component to the glass color, and the
molybdenum contributing a green component to the glass color.
[0039] Other variations as are known to those of skill in the art
may be resorted to without departing from the scope of the
invention as defined by the claims that follow.
* * * * *