Brown glass which absorbs ultraviolet radiation

Details Brown glass which absorbs ultraviolet radiation Brown glass which absorbs ultraviolet radiation

1998-04-14

2000-04-11

Group, Karl

Compositions: ceramic

Ceramic compositions

Glass compositions, compositions containing glass other than...

501 59, 501 68, 501 69, 501 70, 501 71, 501905, C03C 3112, C03C 3083

Patent

active

060488123

DESCRIPTION:

BRIEF SUMMARY
FIELD OF THE INVENTION

Alkali metal aluminosilicate glasses that contain V.sub.2 O.sub.5 to absorb ultraviolet radiation, that contain fluorine as an anti-foaming agent, and that contain a combination of colorant oxides to provide a brown color.
The invention relates to brown glasses which absorb ultraviolet radiation. Brown ophthalmic sunglasses have been commercially available for a number of years.
Recently, general awareness has seen the light with regard to the need to better protect oneself from ultraviolet radiation. This is expressed in particular by the concern with improving the filtering of this radiation by glasses intended for ophthalmic sun protection. Commercial glasses fulfilling this function already exist and are essentially based on the ability of iron oxide to absorb ultraviolet radiation when it is in its oxidized form, that is to say in ferric form.
However, the industrial manufacturing of a brown glass containing iron oxide and in which said iron is in the Fe.sup.3 + form is complicated by the fact that it is necessary to maintain oxidizing conditions during the production of the glass.
Moreover, the UV absorption characteristics of the glasses containing ferric oxide as the UV radiation absorber are not completely satisfactory, particularly with regard to the extent of the range of wavelengths absorbed.
There is consequently a need for brown glasses which absorb UV radiation with improved performance and simpler manufacturing. The invention aims to meet this need.


SUMMARY OF THE INVENTION

More particularly, the invention relates to brown glasses which absorb ultraviolet radiation, which are characterized by the fact that they have the following composition, expressed in wt % based on the oxides:


______________________________________ Broad Range Preferred Range ______________________________________ SiO.sub.2 59-78 61-68 Al.sub.2 O.sub.3 2-6 3-5 B.sub.2 O.sub.3 0-3 0-1.5 Na.sub.2 O 7-16 10-15 K.sub.2 O 2-9 2-5 CaO 0-7 5-7 BaO 0-12 0-10 ZnO 0-12 0-10 ZrO.sub.2 0-6 0-2 TiO.sub.2 0-6 0-3 MnO.sub.2 0.25-6 1-3.5 V.sub.2 O.sub.5 1-3 1-2.5 Fe.sub.2 O.sub.3 0-1.5 0-1 NiO 0-0.5 0.1-0.4 CoO 0-0.1 0.0050-0.0500 Sb.sub.2 O.sub.3 0-0.7 0-0.5 As.sub.2 O.sub.3 0-0.7 0-0.5 F 0.05-1.0 0.1-0.75 With MnO.sub.2 + Fe.sub.2 O.sub.3 + V.sub.2 O.sub.5 >1.5 >2.0 Al.sub.2 O.sub.3 + SiO.sub.2 .gtoreq.65 .gtoreq.65 ______________________________________


BRIEF DESCRIPTION OF THE DRAWING

The single FIGURE in the accompanying drawing is a graphical representation of chromaticity coordinate x and y, and shows a chromaticity box defining a color area produced in accordance with the present invention.


DESCRIPTION OF THE INVENTION

The glasses of the invention, under a thickness of 2 mm, absorb practically all the UV radiation up to a wavelength of 380 nm and even 400 nm in the case of the preferred glasses.
The color of the glasses of the invention can be adjusted very precisely by a sensible addition of conventional coloring oxides such as NiO, CoO, and others, to the base coloring oxides which Fe.sub.2 O.sub.3 and MnO.sub.2 are. In particular, it is possible to produce glasses which, under a thickness of 2 mm, have a visible light transmission percentage of less than 22%, as is required for applications in the making of sunglasses, and a chromaticity contained inside a polygon ABCDA which is represented in the drawing.
In the single FIGURE in the attached drawing, x chromaticity coordinates are plotted on the horizontal axis, and the y coordinates are plotted on the vertical axis. The elongated polygon ABCDA encompasses coordinate combinations that provide generally acceptable colors in accordance with the invention. The polygon is defined by the following chromatic coordinates:


______________________________________ x y ______________________________________ A 0.4000 0.3600 B 0.4650 0.3850 C 0.4650 0.4300 D 0.4000 0.4100 ______________________________________
Moreover, the visible light transmission spe

REFERENCES:
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patent: 5403789 (1995-04-01), Kerko et al.
patent: 5405811 (1995-04-01), Kerko et al.
patent: 5422755 (1995-06-01), Morgan
patent: 5446007 (1995-08-01), Krashkevich et al.
patent: 5558942 (1996-09-01), Itoh et al.
patent: 5656560 (1997-08-01), Stotzel et al.

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