Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Reexamination Certificate
2001-09-17
2003-09-23
Sample, David (Department: 1755)
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
Reexamination Certificate
active
06624102
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an ultraviolet and infrared radiation absorbing glass having a high visible light transmittance and a green tint. More particularly, the invention relates to an ultraviolet and infrared radiation absorbing green glass which, when heat-tempered before use, is inhibited from changing in color through the heat-tempering and which is hence especially suitable for use as an automotive window glass.
BACKGROUND OF INVENTION
In order to meet the demand for protection of interior trim of automobiles against deterioration, which has been increasing with the recent trend to luxury of the interior trim, and to reduce the load of air conditioning, various glasses having ultraviolet and infrared radiation absorbing power have recently been proposed as automotive window glasses.
Among the automotive window glasses, the front or side window glasses should have a visible light transmittance of not less than a certain value so as to secure driver's view. Glasses which have been designed for use in such a position and to which ultraviolet radiation absorbing properties and heat radiation absorbing properties have been imparted, have a greenish tint because an end of the ultraviolet absorption range and an end of the infrared absorption range reside in the visible region.
Window glasses which have an ultraviolet transmittance of about 38% or less and a total solar energy transmittance of about 46% or less and which further have a visible light transmittance of at least 70% so as to secure a view from the inside of the automobile have conventionally been known (see, for example, JP-A-3-187946). (The term “JP-A” as used herein means an “unexamined published Japanese patent application”.)
It is known that one method effective in reducing the total solar energy transmittance of a glass is to increase the absolute amount of ferrous oxide among the iron oxides contained in the glass. Most of the infrared radiation absorbing glasses which have been proposed so far are produced with this technique.
On the other hand, various techniques for reducing ultraviolet transmittance have been proposed. For example, the infrared and ultraviolet radiation absorbing glass disclosed in JP-A-4-193738 contains cerium oxide and titanium oxide so as to have a reduced ultraviolet transmittance. This glass comprises, in % by weight, base glass components comprising 68 to 72% SiO
2
, 1.6 to 3.0% Al
2
O
3
, 8.5 to 11.0% CaO, 2.0 to 4.2% MgO, 12.0 to 16.0% Na
2
O, and 0.5 to 3.0% K
2
O and, coloring components comprising 0.65 to 0.75% Fe
2
O
3
, 0.20 to 0.35% CeO
2
, and 0.2 to 0.4% TiO
2
.
The ultraviolet radiation absorbing glass disclosed in JP-A-6-56466 which has a green tint, comprises a soda-lime-silica glass as base glass components and, coloring components comprising 0.53 to 0.70% total iron oxide in terms of Fe
2
O
3
, 0.5 to 0.8% CeO
2
, and 0.2 to 0.4% TiO
2
, wherein 30 to 40% of the total iron oxide in terms of Fe
2
O
3
is accounted for by FeO in terms of Fe
2
O
3
.
The ultraviolet and infrared radiation absorbing glass disclosed in JP-B-6-88812 (the term “JP-B” as used herein means an “examined Japanese patent publication”) which has a green tint comprises, in % by weight, base glass components comprising 65 to 75% SiO
2
, 0 to 3% Al
2
O
3
, 1 to 5% MgO, 5 to 15% CaO, 10 to 15% Na
2
O, and 0 to 4% K
2
O and, coloring components comprising 0.65 to 1.25% total iron oxide in terms of Fe
2
O
3
and either 0.2 to 1.4% CeO
2
or a combination of 0.1 to 1.36% CeO
2
and 0.02 to 0.85% TiO
2
.
Furthermore, glasses which have a preferred tint by adding nickel oxide have been proposed. For example, the glass disclosed in JP-W-8-506314 (the term “JP-W” as used herein means an “unexamined published PCT application”) comprises a soda-lime-silica glass having a ferrous content calculated with the following equation:
FeO (wt %)≧0.007+[(optical density)−0.036]/2.3 and contains 0.25 to 1.75% by weight Fe
2
O
3
. It further contains one or more members selected from the group consisting of Se, Co
3
O
4
, Nd
2
O
3
, NiO, MnO, V
2
O
5
, CeO
2
, TiO
2
, CuO, and SnO and thereby has an neutral tint. This glass has a visible light transmittance of 32% or more, an ultraviolet transmittance of 25% or less, and a solar heat radiation transmittance lower by at least 7% than the visible light transmittance, when it has a thickness of 4 mm. It preferably has a dominant wavelength shorter than 570 nm.
The glasses disclosed in the patent documents cited above have ultraviolet radiation absorbing power by Fe
2
O
3
, CeO
2
, and TiO
2
and by interactions among them. However, glasses containing these ingredients assume a yellow tint through heat-tempering. Although the reasons for this color change are unclear, it may be due to the fact that an increase in absorption is observed, which is presumably attributable mainly to an interaction between Fe
2
O
3
and CeO
2
. Because of this, a glass plate produced and a glass plate obtained by processing (heat-tempering) the glass plate so as to be actually usable as an automotive window glass differ in tint. In this respect, those conventional glasses have had a drawback in quality control. In particular, an increase in saturation caused by heat-tempering is undesirable because the color becomes more vivid.
On the other hand, in the glasses containing NiO, the color change through heat-tempering can be inhibited due to the absorption by tetra-coordinated NiO after heat-tempering in combination with the coloration in yellow mentioned above. However, the conventional glasses containing NiO have too low a visible light transmittance or too high an ultraviolet or infrared transmittance and are hence unsatisfactory for use as automotive window glasses.
SUMMARY OF THE INVENTION
The invention has been made in the light of the above-described circumstances of the conventional techniques. An object of the invention is to provide an ultraviolet and infrared radiation absorbing green glass which has a high visible light transmittance, a low ultraviolet transmittance, and a low infrared transmittance, changes little in color through heat-tempering, and retains a stable green tint. Another object of the invention is to provide an ultraviolet and infrared radiation absorbing green glass which, in addition to these properties, has a lower total solar energy transmittance than conventional ones due to the infrared absorption by NiO and which therefore is especially suitable for use as an automotive window glass.
(1) The invention provides an ultraviolet and infrared radiation absorbing green glass comprising: in % by weight,
as coloring components,
0.5 to 1.1%, excluding 0.5%, total iron oxide in
terms of
Fe
2
O
3
(T—Fe
2
O
3
);
0 to 2.0% CeO
2
;
0 to 1.0% TiO
2
;
0.0005 to 0.01% NiO; and
0.0001 to 0.001% CoO;
wherein, when the glass has a thickness of 4 mm, the glass has a visible light transmittance (YA) of 70% or more, a total solar energy transmittance (TG) of 60% or less, and an ultraviolet transmittance defined by ISO 9050 (Tuv) of 25% or less
(2) In the glass of the invention, the preferred content of CeO
2
is from 0.1 to 2.0% by weight.
(3) The glass of the invention preferably comprises: in % by weight,
as base glass components,
65 to 80% SiO
2
;
0 to 5% Al
2
O
3
;
0 to 10% MgO;
5 to 15% CaO:
10 to 20% Na
2
O;
0 to 5% K
2
O; and
0 to 5% B
2
O
3
;
wherein the sum of MgO and CaO is 5 to 15% and the sum of Na
2
O and K
2
O is 10 to 20%.
(4) In the glass of the invention, the content of T—Fe
2
O
3
is preferably from 0.6 to 1.1%, excluding 0.6%.
(5) FeO in terms of Fe
2
O
3
preferably accounts for 20 to 60% of the T—Fe
2
O
3
.
(6) The glass of the invention preferably contains 0.0001 to 0.1% in total of at least one selected from the group consisting of Se, Cr
2
O
3
, Mn
2
O
3
, CuO, Nd
2
O
3
, Er
2
O
3
, MoO
3
, V
2
O
5
, and La
2
O
3
.
(7) The glass of the invention preferably, when the glass has a thickness of 4 mm, has a visible light transmittance (YA) of 70% or more, a total solar energy transmittance (TG) of 53% or les
Nagashima Yukihito
Seto Hiromitsu
Yoshii Shigekazu
Nippon Sheet Glass Co. Ltd.
Sample David
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