Coating processes – Immersion or partial immersion
Reexamination Certificate
1999-11-17
2002-04-23
Jones, Deborah (Department: 1775)
Coating processes
Immersion or partial immersion
C427S443100
Reexamination Certificate
active
06376023
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a titanium oxide-containing substrate that has various functions such as deodorizing, stain resisting (stain proofing or stain releasing), and antibacterial functions because of the photo-catalytic action of titanium oxide, and a process for preparing the same.
BACKGROUND ART
Conventionally, it is known that titanium oxide has a photo-catalytic action, by which it decomposes organic matters. The mechanism of decomposing organic matters by this photo-catalytic action is as follows: When titanium oxide is irradiated with light such as visible or ultraviolet rays, charge separation occurs, and electrons and highly oxidizable electron holes are formed. The electron holes react with water vapor or oxygen in air to form reaction active species such as OH radicals or O
2
−
, which decompose organic matters that are present around them instantly. At present, titanium oxygen is used for environmental clean-up of deodorizing, stain resisting, and antibacterial treatments etc. by utilizing its photo-catalytic action.
However, although adhesives have been used for attaching titanium oxide to materials such as metals, glass, wood, or the like, there has been a problem that the adhesives are deteriorated by the photo-catalytic action of titanium oxide, so that the attached titanium oxide is peeled off. Furthermore, when titanium oxide is attached to a substrate formed from resins, synthetic fibers, or the like, it may be attached by mixing it in the substrate during the formation of the substrate, instead of using adhesives as mentioned above. It is herein noted that light such as visible or ultraviolet rays is required for causing the photo-catalytic action of titanium oxide, and moreover, it is necessary that titanium oxide exists on the surface of the substrate so that it may contact with an organic matter that is to be decomposed. However, according to the above-mentioned mixing method, it is difficult to attach titanium oxide on the surface of the substrate, and a large amount of titanium oxide should be mixed in the substrate so that titanium oxide may exist on the surface of the substrate in an amount required to develop various functions such as antibacterial, deodorizing, and stain resisting functions effectively. As a result, this method may affect properties of the substrate, and also is disadvantageous in terms of cost performance. Furthermore, when the substrate is formed from organic matters such as synthetic fibers, resins, or the like, the portion at which titanium oxide is attached is deteriorated, so that the titanium oxide may be peeled off.
Thus, it is an object of the present invention to provide a titanium oxide-containing substrate in which various functions such as deodorizing, stain resisting, and antibacterial functions due to the photo-catalytic action of titanium oxide are displayed sufficiently, and a process for preparing the same, by developing an effective means for attaching titanium oxide to a surface of a substrate, in which peeling of titanium oxide is prevented.
DISCLOSURE OF INVENTION
In order to achieve the above object, the present invention provides a titanium oxide-containing substrate having a surface plated with an anatase type titanium oxide film, the film being adhered to the surface of the substrate without being burned.
Thus, when the substrate has a surface plated with titanium oxide, even if the substrate is formed from organic matters, the portion at which titanium oxide is attached is not deteriorated by the photo-catalytic action of titanium oxide.
Moreover, because the bonding strength of plating is large, titanium oxide is not peeled off. Furthermore, because a surface of the substrate is plated with titanium oxide, the photo-catalytic action of titanium oxide is displayed sufficiently, so that the substrate exhibits various functions such as excellent deodorizing, stain resisting, and antibacterial functions.
In the present invention, the surface of the substrate may be coated with titanium oxide completely, or may be coated partially. It is preferable that titanium oxide is attached to the surface of the substrate uniformly in a ratio of 1 to 10% (particularly a ratio of 2 to 5%) on an area basis.
In the titanium oxide-containing substrate of the present invention, it is preferable that the substrate is at least one selected from the group consisting of synthetic fibers, glass, metals, resins, and wood. Moreover, the substrate also may be formed from proteins, cellulose, or the like.
In the titanium oxide-containing substrate of the present invention, it is preferable that a noble metal is included in the titanium oxide film. This is because the photo-catalytic action of the titanium oxide is further accelerated by incorporating the noble metal, and also effects characteristic of the noble metal can be obtained. Furthermore, it is preferable that the noble metal is incorporated by plating as in the case of titanium oxide.
Furthermore, in the titanium oxide-containing substrate of the present invention, it is preferable that gold is included in the titanium oxide film, and a function of decomposing organic matters by oxidation is developed even in the absence of light.
Moreover, in the present invention, the titanium oxide and the noble metal in the substrate may be either ionic or non-ionic.
Next, the process for preparing the titanium oxide-containing substrate of the present invention comprises: adding a titanium fluoride in an aqueous solvent to prepare a solution; and bringing the solution into contact with a surface of a substrate while adding boric acid, malic add, and citric acid to the solution; whereby the surface of the substrate is plated with an anatase type titanium oxide film. It is preferable that the pH of the solution in which boric acid, malic acid, and citric acid are added is in the range of 3 to 5.
In the process for preparing the titanium oxide-containing substrate of the present invention, it is preferable that titanium tetrafluoride is used as the titanium fluoride because of its excellent reactivity.
In the process for preparing the titanium oxide-containing substrate of the present invention, it is preferable that at least one selected from the group consisting of synthetic fibers, glass, metals, resins, and wood is used as the substrate. Moreover, other than these materials, those materials as mentioned above also may be employed.
Because of the same reasons as mentioned above, in the process for preparing the titanium oxide-containing substrate of the present invention, it is preferable that a noble metal is incorporated in the titanium oxide film.
Moreover, in the present invention, the “substrate” includes substrates after being processed into products as well as substrates before being processed into products. Furthermore, it also includes substrates formed on a surface of other objects, such as coating films.
BEST MODE FOR CARRYING OUT THE INVENTION
The titanium oxide-containing substrate of the present invention is prepared, for example, as follows. In the following, “% owf” represents percentage by weight to the weight of the substrate to be treated. For example, 5% owf of an additive in the case of treating 3 kg of substrate indicates 150 g of the additive.
First, a substrate to be treated is prepared. The materials as mentioned above mentioned may be employed as this substrate. Furthermore, the shape of the substrate is not particularly limited, and it may be in the form of, e.g. fiber, plate, rod, or the like.
On the other hand, a titanium fluoride is added to an aqueous solvent to prepare a treating solution. Usually, water is used as the aqueous solvent. Furthermore, other than the above-mentioned titanium tetrafluoride, titanium trifluoride or the like also can be used as the titanium fluoride. In this case, the ratio of the titanium fluoride is usually from 0.1 to 5% owf, preferably about 2.0% owf Moreover, by changing this ratio, the ratio of the titanium oxide introduced into the surface of the substrate can be adjusted.
Then, the treati
Jones Deborah
Kyorasha Co., Ltd.
McNeil Jennifer
Merchant & Gould P,C,
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