Stock material or miscellaneous articles – Composite – Of quartz or glass
Reexamination Certificate
1999-12-20
2002-09-17
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of quartz or glass
C428S632000, C428S658000, C428S673000, C428S702000
Reexamination Certificate
active
06451434
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a glass laminate, a functional transparent article and a method of its production, particularly to a glass laminate which does not deteriorate in optical properties or electrical properties when heated for processing such as tempering or bending by virtue of its excellent heat resistance, and therefore is suitable as a material for functional transparent articles, a method of producing a functional transparent article excellent in optical properties and electrical properties by using the glass laminate as a material and the functional transparent article.
2. Discussion of Background
In recent years, functional glasses having a laminated coating containing a layer mainly composed of silver as a selective optically reflective coating or an electrically conductive coating are used as a heat reflective glass such as a Low-E glass (Low Emission Glass), an electromagnetic glass shield or an electric glass heater for windshields of automobiles and trains, for window-panes for architectural use in houses and buildings and for the face plates of plasma displays.
A laminated coating containing a layer mainly composed of silver has a high light transmittance in the visible region and high reflectance to near infrared light and infrared light with long wave lengths of about 10 &mgr;m. Therefore, a glass having a laminated coating containing a layer mainly composed of silver not only allows visible light from the outside to enter but also diminishes entering heat rays of sunlight, and thereby lightens air-conditioning loads in the summer. In particular, when used for a double glazing, it can also diminish heat emitted from the inside, and thereby prevents dew condensation on window-panes and lightens heating loads in the winter. In short, it can be used as a high-efficiency heat reflective glass which has a high visible light transmittance and an excellent heat shielding effect, especially as a Low-E glass.
Further, a laminated coating containing a layer mainly composed of silver has a sheet resistance of 10 &OHgr;/□ or less and has a low resistances among various transparent conductive coatings. Therefore, it can be used for a transparent electromagnetic glass shield or an electric glass heater.
For a laminated coating containing a layer mainly composed of silver, a multilayer laminated structure comprising a metal layer mainly composed of silver (hereinafter referred to simply as a “Ag-based layer”) and layers composed of oxides or nitrides of Zn, Ti, Sn or Si is known. For example, a glass laminate comprising a glass substrate and three layers of ZnO/Ag/ZnO or five layers of ZnO/Ag/ZnO/Ag/ZnO formed on the glass substrate is known.
On the other hand, glass laminates are expected to be processed into various shapes or tempered according to their use. In forming (such as bending)or tempering procedure, heat treatment at about 570 to 700° C. is followed by molding or quenching treatment. For example, heat reflective glasses used for windshields, especially front an rear windshields of automobiles are bent into curved shape after heated to about 570 to 700° C. Heat reflective glasses for architectural use as window-panes are sometimes also formed into not planar but curved or complicated shapes according to the shapes of windows of buildings.
However, conventional glass laminates sometimes do not show desired performance because heating (so-called post-heating) treatment for forming or tempering after lamination of Ag-based layers and transparent protective layers impairs the properties of the Ag-based layers and deteriorates the optical properties and electrical properties. This problem might be solved by laminating Ag-based layers and transparent protective layers on a glass substrate preliminarily formed into a predetermined shape. However, in order to form Ag-based layers and transparent protective layers on a molded glass, for example on a curved glass by sputtering in the same chamber, because each layer is formed in a different atmosphere, a production procedure in which sputtering gases are changed while the substrate is shuttled have to be adopted. The production procedure is inferior in productivity, restricts production output and can hardly reduce costs.
In order to remove these problems, various post-heat treatable glass laminates have been proposed.
For example, JP-A-10-503745 discloses a transparent article comprising a transparent non-metallic substrate and a transparent film stack containing at least one infrared reflective metal film deposited by sputtering on the substrate, a dielectric film formed on the metal film and a silicon nitride protective film formed on the dielectric film.
Japanese Patent Publication of Japanese Patent No. 2509925 has proposed a glass substrate having a coating comprising a silver layer of 5-30 nm thick; an additional metal layer of aluminum, titanium, zinc or tantalum formed on the silver layer; and an anti-reflective metal oxide layer formed on the additional metal layer. This publication has also proposed a method of producing a curved and/or tempered silver-coated glass substrate characterized in that a glass substrate is subjected to bending and/or tempering cycles in which the substrate is heated to the softening point of the glass or above so that high light transmittance is imparted to the coated glass during the bending and/or tempering cycles.
Further, JP-A-8-238710 has proposed a transparent substrate having a metal layer characteristic in the infrared region, a first dielectric coating formed under the metal layer, a second dielectric coating formed on the metal layer and a protective metal layer which is formed directly on the metal layer and in contact with the metal layer, wherein the second coating contains at least one barrier layer of at least 10 nm thick against diffusion of oxygen which is made of at least one member selected from silicon compounds SiO
2
, SiO
x
C
y
and SiO
x
N
y
, nitrides such as Si
3
N
4
and AlN and carbides such as SiC, TiC, CrC and TaC, and the upper metal layer is in direct contact with the lower dielectric coating.
JP-A-62-216944 has proposed a method of producing a window-pane having high transmitting properties in the visible spectral region and high heat reflective properties, which comprises coating a substrate made of an inorganic glass with:
a) a first layer comprised of an oxide selected from the group consisting of tin oxide, silicon dioxide, aluminum oxide, tantalum oxide and zirconium oxide and their mixed oxides,
b) a second layer comprised of a metal selected from the group consisting of tantalum, tungsten, nickel and iron and alloys comprising one of them in an amount of at least 50 wt %,
c) a third layer composed of silver or a silver alloy containing at least 50 wt % of silver,
d) a fourth layer composed of a metal selected from the same group as the second layer, and
e) a fifth layer composed of an oxide selected from the same group of oxides as the first layer,
wherein the substrate is heated to at least the softening point of the glass together with a packet of all the layers a) to e), plastically deformed under heating and cooled in the deformed state.
Furthermore, JP-A-5-213632 has proposed a method of producing heat treated coated glass comprising forming on a glass substrate a heat shielding film of a metal such as SUS, Ti or Cr, or a nitride, boride or carbide thereof, then forming a first protective layer of a zirconium siliconitride or the like which is transparent in the visible region and remains transparent even after oxidation, and further forming a second protective layer of an oxide such as tin oxide having a high barrier property.
However, these conventional glass laminates proposed so far are not satisfactory in heat resistance during post-heating and have a problem that heat treatment involved in processing impairs Ag-based layers and deteriorates optical properties.
BRIEF SUMMARY OF THE INVENTION
The object of the present invention is to provide a glass laminate which doe
Aomine Nobutaka
Decroupet Daniel
Ebisawa Junichi
Noda Kazuyoshi
Takeda Satoshi
Asahi Glass Company Limited
Jones Deborah
Piziali Andrew
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