Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Reexamination Certificate
2002-10-03
2004-08-31
Group, Karl (Department: 1755)
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
C501S064000
Reexamination Certificate
active
06784129
ABSTRACT:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT
The present invention relates to an ultraviolet/infrared absorbent low transmittance glass. More particularly, it relates to an ultraviolet/infrared absorbent low transmittance glass having a grayish green shade, a low visible light transmittance, a low solar energy transmittance, and a low ultraviolet transmittance, so that it is useful for windows of vehicles or buildings particularly for a privacy protecting glass in a rear window of a vehicle.
Recently, a variety of glasses with capable of absorbing ultraviolet/infrared light to be used as a vehicle windshield has been proposed for preventing degradation of luxurious interior materials and reducing cooling load of the vehicle. In view of privacy protection, a glass with relatively low visible light transmittance is preferably used for a rear window glass of a vehicle. Such kinds of glass include the followings.
For example, a dark gray colored infrared absorbent glass disclosed in Japanese Patent Publication No. 07-29813B consists of the soda-lime-silica glass including colorants consisting of 1.00 to 1.7 weight percent of Fe
2
O
3
(total iron), at least 0.27 weight percent of FeO, 0.002 to 0.005 weight percent of Se, and 0.01 to 0.02 weight percent of CoO. The glass exhibits less than 32 percent of the luminous transmittance and less than 15 percent of the total solar infrared transmittance at 3.9 mm thickness.
A dark gray colored glass disclosed in Japanese Patent Publication No. 08-157232A consists of a soda-lime-silica glass including colorants consisting of 0.8 to 1.4 weight percent of Fe
2
O
3
(total iron), less than 0.21 weight percent of FeO, 0.05 to 1.0 weight percent of TiO
2
, 0.02 to 0.05 weight percent of CoO, and 0.0005 to 0.015 weight percent of Se.
A neutral gray colored glass disclosed in claim 25 of U.S. Pat. No. 5,393,593 consists of a soda-lime-silica glass including colorants consisting of 1.00 to 2.2 weight percent of Fe
2
O
3
(total iron), at least 0.20 weight percent of FeO, 0.0005 to 0.005 weight percent of Se, and 0.010 to 0.030 weight percent of CoO. The glass exhibits less than 35 percent of the luminous transmittance and less than 20 percent of the total solar infrared transmittance at 3.9 mm thickness.
A glass disclosed in PCT (Japanese phase) No. 07-508971 consists of a soda-lime-silica glass including colorants consisting of 1.3 to 2.0 weight percent of Fe
2
O
3
(total iron), about 0.01 to 0.05 weight percent of NiO, about 0.02 to 0.04 weight percent of Co
3
O
4
, about 0.0002 to 0.003 weight percent of Se and 18 to 30 weight percent of a ferrous iron value, resulting in less than 0.53 of a light and shade coefficient.
In both the dark gray colored infrared absorbent glass disclosed in Japanese Patent Publication No. 07-29813B and the neutral gray colored glass disclosed in U.S. Pat. No. 5,393,593, a great quantity of Se is used for providing a desirable color. However, such a great quantity of Se is not favorable for the environment because Se is toxic and easy to vaporize. The above dark gray glass disclosed in Japanese Patent Publication No. 08-157232A including 0.05 to 1.0 weight percent of TiO
2
as an essential component is not preferable because TiO
2
is expensive to thereby increase a cost.
The aforementioned glass includes the high concentration of selenium to provide optical properties, essentially without including nickel.
The glass disclosed in PCT (Japanese phase) No. 07-508971 is prepared from a standard soda-lime-silica glass, to which iron oxide, cobalt oxide, nickel oxide and selenium are added in a specific ratio. However, the glass composition disclosed therein has the great concentration of selenium and a small amount of nickel oxide.
It is an object of the present invention to provide an ultraviolet/infrared absorbent low transmittance glass having a grayish green shade, a low visible light transmittance, a low solar energy transmittance and a low ultraviolet transmittance, thus it is useful for a window of a vehicle or a building, particularly for a privacy protecting glass of a rear window of a vehicle.
SUMMARY OF THE INVENTION
An ultraviolet/infrared absorbent low transmittance glass of the present invention is formed of a base glass and a colorant, wherein major constituents of the base glass are 65 to 80 wt. % of SiO
2
; 0 to 5 wt. % of Al
2
O
3
; 0 to 10 wt. % of MgO and 5 to 15 wt. % of CaO wherein a total amount of MgO and CaO is between 5 and 15 wt. %; 10 to 18 wt. % of Na
2
O and 0 to 5 wt. % K
2
O wherein a total amount of Na
2
O and K
2
O is between 10 and 20 wt. %; and 0 to 5 wt. % of B
2
O
Also, the colorant includes more than 0.95 and less than 1.2 wt. % of total iron oxide (T-Fe
2
O
3
) expressed as Fe
2
O3, i.e. 0.95<T-Fe
2
O
3
<1.2; 0.001 to 0.03 wt. % of CoO; and 0.003 to 0.2% of NiO.
The glass of the present invention does not substantially contain Se. The glass of the present invention is preferable to be reinforced by blasting air cooling for a desired color shade.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
Hereunder, embodiments of an ultraviolet/infrared absorbent low transmittance glass composition will be explained. It should be noted that components are represented in weight percentage.
SiO
2
(silica) is a principal component of the ultraviolet/infrared absorbent low transmittance glass. Less than 65% of SiO
2
lowers durability of a glass and more than 80% of SiO
2
raises a melting temperature of a glass too high.
Al
2
O
3
is a component for improving the durability of the glass. More than 5% Al
2
O
3
raises a melting temperature of a glass too high. A preferable range of Al
2
O
3
is between 0.1% and 2%.
MgO and CaO are used to improve the durability of a glass and adjust a devitrification temperature and a viscosity of a glass during molding. More than 10% of MgO raises the devitrification temperature. Less than 5% or more than 15% CaO raises the devitrification temperature of a glass. The durability of a glass is lowered when the total amount of MgO and CaO is less than 5%, while the devitrification temperature is increased when the total amount of MgO and CaO exceeds 15%.
Na
2
O and K
2
O prompt a glass to melt. An efficiency of promoting the melting becomes poor when Na
2
O is less than 10% or the total of Na
2
O and K
2
O is less than 10%, while the durability of a glass is lowered when Na
2
O exceeds 18% or the total of Na
2
O and K
2
O exceeds 20%. It is preferable for K
2
O not to exceed 5% because of a cost.
B
2
O
3
is a component for improving the durability of a glass, prompting to melt, and yet enhancing the ultraviolet absorption. B
2
O
3
should be less than 5%, since it becomes difficult to mold due to vaporization of B
2
O
3
.
Iron oxide is present in the form of Fe
2
O
3
and FeO in the glass. Fe
2
O
3
is a component for improving the ultraviolet absorption and FeO is a component for improving the heat rays absorption. The iron in the composition of the glass makes the glass green tint.
When a total amount of iron oxide (T-Fe
2
O
3
) expressed as Fe
2
O
3
is less than 0.95%, the efficiency of ultraviolet and infrared absorption becomes too small to provide desired optical properties. On the other hand, when T-Fe
2
O
3
exceeds 1.2%, it is difficult to obtain a desired grayish color shade because a large amount of iron makes the color green tint too much.
When T-Fe
2
O
3
is not greater than 1.1%, iron in the composition is effective in coloring the glass green tint and improves the visible light transmittance, thus other colorants can be added to adjust the shade. T-Fe
2
O
3
is therefore contained in an amount between 0.95% and 1.2%, preferably not more than 1.1%.
Fe
2
O
3
particularly has a function of increasing the light absorption in the ultraviolet range when the glass is reinforced by air blast cooling. This means that the glass of this invention can obtain enough efficiency of the ultraviolet absorption without using expensive ultraviolet absorbent such as CeO
2
and TiO
2
. When T-Fe
2
O
3
is in the range mentioned above, the desired col
Nagashima Yukihito
Seto Hiromitsu
Yoshii Shigekazu
Group Karl
Kanesaka Manabu
Nippon Sheet Glass Co. Ltd.
LandOfFree
Ultraviolet/infrared absorbent low transmittance glass does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Ultraviolet/infrared absorbent low transmittance glass, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Ultraviolet/infrared absorbent low transmittance glass will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3277889