Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Reexamination Certificate
2001-09-06
2003-04-08
Sample, David (Department: 1755)
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
C501S071000
Reexamination Certificate
active
06544915
ABSTRACT:
TECHNICAL FIELD
The present invention relates to an infrared and ultraviolet radiation absorbing glass having a green tint. More particularly, it relates to an infrared and ultraviolet radiation absorbing glass having high transmission and pale bluish green tint which is suitable for use as a glass for automobiles or a glass for construction.
BACKGROUND ART
In recent years, interior trim of automobiles tends to be luxury, and from the standpoint of the demand to protect the interior trim from deterioration and reduce load of air conditioning, a green-tined glass having infrared and ultraviolet radiation absorbing power imparted thereto has been proposed as window glass of automobiles.
For example, JP-A-4-310539 (the term “JP-A” used herein means an “unexamined published Japanese patent application”) discloses an infrared and ultraviolet radiation absorbing glass consisting essentially of, in % by weight, 65-75% SiO
2
, 0.1-5% Al
2
O
3
, 10-18%Na
2
O, 0-5%K
2
O, 5-15% CaO, 1-6% MgO and 0.05-1.0% SO
3
, and having incorporated therein as coloring components, 0.5-1.2% total iron oxide in terms of Fe
2
O
3
, 0.1-3.0% CeO
2
and 0-1.0% TiO
2
, wherein 20-40% of the total iron oxide in terms of Fe
2
O
3
is FeO.
JP-A-5-78147 discloses an infrared and ultraviolet radiation absorbing glass as a glass having relatively pale green tint in various infrared and ultraviolet radiation absorbing glasses. This glass comprises, in % by weight, basic components comprising 68-72% SiO
2
, 1.6-3.0 Al
2
O
3
, 8.5-11.0% CaO, 2.0-4.2% MgO, 12.0-16.0% Na
2
O, 0.5-3.0% K
2
O and 0.5-3.0% SO
3
, and coloring components comprising 0.58-0.65% total iron oxide in terms of Fe
2
O
3
, 0.1-0.5% CeO
2
, 0.1-0.4% TiO
2
and 10-350 ppm MnO as a trace oxide.
JP-A-6-56466 discloses a glass having low total solar energy transmission and ultraviolet transmission. This glass comprises, in % by weight, a soda-lime-silica basic glass, and having incorporated therein 0.53-0.70% total iron oxide in terms of Fe
2
O
3
, 0.35-0.50% Fe
2
O
3
, 0.16-0.24% FeO, 0.2-0.4% TiO
2
, and 0.5-0.8% total cerium in terms of CeO
2
, wherein an amount of FeO in terms of Fe
2
O
3
is 30-40% based on the weight of the total iron oxide in terms of Fe
2
O
3
.
In the infrared and ultraviolet radiation absorbing glass disclosed in the above-described JP-A-4-310539, the coloring components are preferably 0.7-1.0% total iron oxide in terms of Fe
2
O
3
, and 0.3-2.0 CeO
2
, and a visible light transmission when the glass has a thickness of 5 mm is 66.1-66.8% as shown in the examples. As is understood from this, a green tint of the glass is comparatively dark. However, in some cases such a dark tint may not be preferred as a glass for automobiles, or is not generally preferred as a glass for construction.
In the infrared and ultraviolet radiation absorbing glass disclosed in the above-described JP-A-5-78147, the preferred range of the total iron oxide in terms of Fe
2
O
3
is about 0.6-0.64%. In this case, a visible light transmission is at most about 71%, and thus it cannot say that the visible light transmission is sufficiently high.
The infrared and ultraviolet radiation absorbing glass disclosed in the above-described JP-A-6-56466 includes an infrared and ultraviolet radiation absorbing glass having relatively high visible light transmission. However, in order to obtain high total solar energy absorbing power, an amount of divalent iron in terms of Fe
2
O
3
is 30-40% by weight based on the weight of the total iron in terms of Fe
2
O
3
. As a result, melting under stronger reducing condition than the general is required. Further, the total cerium in terms of CeO
2
is 0.5-0.8%, which is relatively large. This results in making it difficult to conduct melting under strong reducing condition, and also increases raw material cost.
DISCLOSURE OF THE INVENTION
The present invention has been made in view of the above-described problems in the prior art.
Accordingly, an object of the present invention is to provide an infrared and ultraviolet radiation absorbing glass having green tint, and in particular an infrared and ultraviolet radiation absorbing glass having high transmission and pale bluish green tint which is suitable for use as a glass for automobiles or a glass for construction.
According to the present invention, there is provided an infrared and ultraviolet radiation absorbing glass comprising, in % by weight:
a soda-lime-silica basic glass, and
coloring components comprising
0.40 to less than 0.58% total iron oxide (T—Fe
2
O
3
) in terms of Fe
2
O
3
,
0.05 to less than 0.5% CeO
2
,
0 to 0.5% TiO
2
, and
0.0001 to 0.002% CoO,
wherein 20 to less than 30% of T—Fe
2
O
3
is FeO in terms of Fe
2
O
3
.
The content of TiO
2
is preferably 0 to less than 0.2%, more preferably 0 to less than 0.1%.
The infrared and ultraviolet radiation absorbing glass composition preferably further comprises 200 ppm or less of MnO.
The infrared and ultraviolet radiation absorbing glass preferably has, when the glass has a thickness of 3.25 to 6.25 mm, optical characteristics such that a visible light transmission measured with CIE standard illuminant A at a wavelength region of 380 to 770 nm is 75% or more, a dominant wavelength measured with CIE standard illuminant C at a wavelength region of 380 to 770 nm is 490 to 515 nm, a total solar energy transmission measured at a wavelength region of 300 to 2,100 nm is less than 55%, and an ultraviolet transmission defined by ISO 9050 is less than 20%.
BEST MODE FOR CARRYING OUT THE INVENTION
The reason for limitations of the glass composition of the infrared and ultraviolet radiation absorbing glass according to the present invention are described below. Unless otherwise indicated, all % are by weight.
The soda-lime-silica basic glass used herein means a general float composition, but may be a composition for thin plate in which contents of SiO
2
, alkali oxides and alkaline earth oxides are increased or decreased to increase a coefficient of thermal expansion or Young's modulus of a glass, thereby facilitating thermal tempering, and a composition in which absorption position of coloring components is changed.
The iron oxide is present in a glass in the form of Fe
2
O
3
and FeO. Fe
2
O
3
is a component to enhance the ultraviolet absorbing power together with CeO
2
and TiO
2
, and FeO is a component to enhance the absorption power of solar heat rays.
In order to obtain desired visible light transmission and total solar energy absorbing power, the content of the total iron oxide (T—Fe
2
O
3
) must be in a range of 0.40 to less than 0.58%, and the proportion of FeO to T—Fe
2
O
3
(the amount of FeO is generally a value in terms of Fe
2
O
3
) must be in a range of 20 to less than 30%. If the total iron content and the proportion of FeO to T—Fe
2
O
3
are lower than the respective lower limit of the above ranges, the total solar energy absorbing power becomes insufficient, and on the other hand, if those are higher than the respective upper limit of the above ranges, the visible light transmission becomes too low.
In order to obtain a desired ultraviolet absorbing effect in such total iron oxide content and proportion of FeO to T—Fe
2
O
3
, the CeO
2
content must be within a range of 0.05 to less than 0.5%. If the CeO
2
content is less than 0.05%, the ultraviolet absorbing effect is not sufficient, and on the other hand, if it is 0.5% or more, absorption of visible light at a short wavelength side is too large, so that a desired color tint is not obtained and also cost of raw materials increases.
TiO
2
is not an essential component, but can be added in an appropriate amount such that the optical characteristics intended in the present invention are not impaired, in order to increase the ultraviolet absorbing power of a glass. If the TiO
2
content is too large, a glass tends to color yellow. For this reason, the upper limit of the TiO
2
content is generally 0.5%, preferably less than 0.2%, and more preferably less than 0.1%.
CoO, although in a slight content, is an essential component, which is important to prev
Nippon Sheet Glass Co. Ltd.
Sample David
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