Stock material or miscellaneous articles – Composite – Of inorganic material
Reexamination Certificate
2002-09-23
2004-07-13
Jones, Deborah (Department: 1775)
Stock material or miscellaneous articles
Composite
Of inorganic material
C428S701000, C428S702000, C502S349000, C502S350000, C106S286100, C106S286400, C106S286800, C204S192100, C204S192380
Reexamination Certificate
active
06761984
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
When a substrate coated with a photocatalyst film is a glass plate, the glass plate is used in a wide range of fields, for example, window glass for architectural windows, windows for LCDs (liquid crystal display) and PDPs (plasma display panel), a glass substrate for DNA analysis that is used in the field of biotechnology, solar cell panel, etc. Further, when a substrate coated with a photocatalyst film is a resin frame, contamination preventive properties are given to such equipment and facilities as portable information tenninal devices, sanitary facilities, medical facilities, electronic devices, etc. Thus, when coated on various kinds of substrates, a photocatalyst film provides properties to the substrate surfaces by which they exhibit very little contamination or any contamination is easily removed. Further, a photocatalyst film has anti-bacteria action and is applicable to bio-medical inspection chips such as a vio chip or a chemical chip. This invention related to an article having a substrate coated with a photocatalyst film a method for preparing the article and sputtering targets for use in coating the film.
2. Description of the Related Art
In Japanese Laid-Open Patent Publication No. HEI 10-66879, glass plates coated with a titanium oxide film, a zinc oxide film or a tungsten oxide film are disclosed as articles with a photocatalyst film formed on substrates and it is stated that these are best suited for containing such metals as platinum, palladium, nickel, copper, tin in this photocatalyst film in order to improve the photocatalyst activity. It is also stated that this photocatalyst film is coated by reactive sputtering in inactive gas containing oxygen using a metal corresponding to metal oxide forming the photocatalyst film as a target.
In Japanese Laid-Open Patent Publication No. HEI 11-92176, articles coated with a photocatalyst film comprising titanium oxide, etc. obtained by a sputtering method and containing such metallic ions as platinum, nickel, chrome, cobalt, tin, niobium, tantalum doped into its surface by the ion implanting method as disclosed.
Further, in the Japanese Laid-Open Patent Publication No. HEI 11-60281, a photocatalyst glass with a first layer of SiO
2
film containing Al
2
O formed on the surface of a soda lime silica glass and a second layer comprising TiO
2
as a main component formed thereon is disclosed. It is also stated that it is better to mix a metal oxide of Al
2
O
3
, P
2
O
5
, B
2
O, ZrO
2
, P
2
O
5
, SnO
2
, or Ta
2
O into the TiO
2
film thoroughly for the purpose of improving film minuteness, film strength, and alkali resistance, giving conductivity and cutting ultraviolet rays. It is further stated that these metallic oxide films are coated by thermally decomposing such organic metallic compounds as metallic alkoxide, metallic acetylacetonate, etc.
Further, in FIG. 1 of Japanese Laid-Open Patent Publication No. HEI 10-330131, a photocatalyst coated glass article having a good hydrophilic multi-layer structure comprising an Si
2
base layer, a TiO
2
photocatalyst layer and an SiO
2
top layer formed on a plate glass is disclosed. It is stated that this photocatalyst layer comprises mainly titanium oxide with Al
2
O, Y
2
O, Ta
2
O
5
and La
2
O
5
intermixed. It is also stated that these photocatalyst metallic oxide layers are laminated and formed by an electron beam vaporization method.
Out of the existing technology described above, the photocatalyst film disclosed in Japanese Laid-Open Patent Publication No. HEI 10-66879 has such metals as platinum, palladium, etc. mixed in a titanium oxide film in order to increase photocatalyst activity. However, in the oxygen reactive sputtering method using a metal target of titanium, there was such a problem that it was difficult to contain a fixed amount of platinum or palladium as a catalyst activity improving agent in the metallic state without oxidizing the platinum or palladium while oxidizing titanium when coating a titanium oxide film containing such metals as platinum. Further, in the sputtering method using a target of titanium oxide, there was such a problem that it was difficult to a manufacture oxide sintered matter having metallic powder of platinum dispersed uniformly therein.
In the doping of metallic ion by the ion implanting method disclosed in Japanese Laid-Open Patent Publication No. HEI 11-92176, there were such problems that 1) excessive or insufficient doping giving uneven density resulted as metallic ions were dispersed in the depth direction of a film so that uniform doping of the film was impossible, 2) the grid disorder around the substituting side of the implanted metal becomes large and as a result, a dopant does not only function as a donor or an acceptor but also a drop of the photocatalyst activity is caused by increase of recombination center, 3) an amount of ions implanted cannot be greatly increased, 4) several kinds of dopants cannot be implanted at a time while controlling their densities, and 5) as metallic ions are used for doping by ion implantation, it is difficult to apply the metallic ion doping to large sized substrates such as structural window glasses, solar cell panels that are installed on the roof of a house, or glass plates used in relatively large displays.
In the existing technology stated in Japanese Laid-Open Patent Publication No. HEI 11-60281, there was such a problem that after coating organic metallic compounds such a metal alkoxide, metallic acetylacetonate, etc. on a substrate, it was necessary to heat the substrate at a high temperature of 500~600° C., so this technology could not be applied to thermally restricted substrates such as resin made substrates.
Further, the photocatalyst layer of the existing technology shown in FIG. 1 of Japanese Laid-Open Patent Publication No. HEI 10-330131 is laminated and coated by an electron beam vaporization method and it is therefore difficult to apply this technology to large substrates such as, for example, a structural window glass, a solar cell panel installed on a roof of a house, and a relatively large display unit.
This invention is made for solving problems involved in the existing technologies described above and it is a first object to provide articles having more improved photocatalyst activity. A second object of this invention is to provide an article having improved photocatalyst activity even when the surface is large. A third object of this invention is to provide a photocatalyst function to the surface of a substrate even when its thermal resistance is relatively weak. A fourth object of this invention is to provide a method to efficiently coat a substrate with an improved photocatalyst film.
SUMMARY OF THE INVENTION
This invention relates to an article having a substrate with a photocatalyst coating film formed thereon by a sputtering method, characterized in that the photocatalyst coating film comprises: 1) titanium oxide as a main component and 2) at least one kind of metal having a sputtering rate for Ar, which has at least one kind of energy in the ion energy are of 100 to 2000 eV, being 0.9 to 2.7 times that of Ti, preferably at least one kind of metal selected from the group consisting of Fe, V, Mo, Nb, Al and Cr.
The photocatalyst film of this invention contains titanium oxide as a main component and at least one metal selected from the group consisting of Fe, V Mo, Nb, Al and Cr as a component in a small amount. In order to improve the photocatalyst activity of titanium oxide, one or more than two kinds of metals can be contained.
Generally, the improvement of the photocatalyst activity of titanium oxide by metal ion doping has been studied for a long time, and many metals have been examined as additive metals having the effect of improving the photocatalyst activity (for example, “Chemical Introduction 39, Inorganic Photochemical”, 1st Edition, Page 128, Gakkai Shuppan Center, 1983, “Titanium Oxide”, 1st Edition, Page 178, Gihodo, 1991). The reason for the improvement of the photocatalyst activity of ti
Anzaki Toshiaki
Arai Daisuke
Kijima Yoshifumi
Blackwell-Rudasill G.
Jones Deborah
Merchant & Gould P.C.
Nippon Sheet Glass Co. Ltd.
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