Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,...
Patent
1997-10-31
2000-06-13
McKane, Elizabeth
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
428369, 428372, 428378, 428379, 428403, 422121, 422122, 250504R, 264 05, 264 21, B32B 516, B32B 502, A61L 920
Patent
active
06074748&
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a molded article having a photocatalytic function and being effective in deodorization, sterilization and stain resistance.
BACKGROUND ART
Metal oxides such as titanium oxide (TiO.sub.2) have a function of decomposing organic compounds which are in contact therewith or present close thereto by oxidization or reduction when excited by ultraviolet rays, and thus are called photocatalytic semiconductors.
This function is well known and is utilized in a variety of applications. For example, Unexamined Japanese Patent Publication No. 62-66861 discloses an arrangement in which a photocatalytic element having a photocatalytic semiconductor applied to the surface of its base, which is in the form of a film, bead, board or fibrous element, is placed in a glass tube and gas or liquid is circulated through the glass tube. Also, Unexamined Japanese Patent Publication No. 1-143630 discloses an arrangement in which gas or liquid is circulated through a photocatalytic element having a photocatalytic semiconductor applied to the surface of its base which is in the form of a lattice, plate, particle, pleat or net. Further, Unexamined Japanese Patent Publication No. 4-61933 discloses an arrangement in which a photocatalytic semiconductor is applied directly to a stainless steel pipe or a porous fine tube.
In the arrangement of the conventional photocatalytic elements, the photocatalytic semiconductor is applied to a surface of a base which is a member (tube or plate) having a predetermined shape suitable for its use. In such cases, it is difficult to make a functional area of the photocatalytic semiconductor much greater than the surface area of the base. Further, in order for the photocatalytic semiconductor to be applied to the surface of the base, usually the photocatalytic semiconductor in a sol state is applied to the surface of the base and then the base with the photocatalytic semiconductor applied thereto is baked at a predetermined temperature (50 to 500.degree. C.). If, however, the base has a complicated shape, it may be difficult to make the photocatalytic semiconductor adhere to an inside surface of the base, or the base may be deformed due to heat. In addition, if the base is complicated in shape, it is difficult to irradiate its inside surface with ultraviolet rays.
SUMMARY OF INVENTION
An object of the present invention is to provide a molded article with a photocatalytic function capable of having a desired shape and a contact area much larger than an outside surface area thereof, and being sufficiently irradiated with ultraviolet rays even at an inner surface thereof, as needed.
According to one aspect of the present invention, a molded article is produced by gathering unit particles such as glass beads, bonding them one another to a desired shape as a whole, and then forming a photocatalytic functional layer on a surface of each particle.
The unit particles are filled and packed in a mold, and are heated while being lightly pressed due to their own weight and the like to thereby fusion-bond the unit particles to one another. Alternatively, the unit particles are bonded to one another by an adhesive. When bonding, the degree of pressure application and the temperature are set so that the particles maintain their shapes and intercommunicating gaps are formed among the particles. When using an adhesive, it is necessary to chose a suitable adhesive (e.g., water glass or low-melting glass frit) which will not affect properties of the unit particles and the photocatalytic semiconductor, and has an adequate durability in using the molded article as the photocatalytic element.
The molded article produced by gathering unit particles is characterized in capability of having a free shape, for example, blocks of various three-dimensional shapes, such as a tube, gutter, vessel and corrugated plate. Especially, it makes it possible to select shapes of components which have been physically or economically impractical to produce by conventional techniques and shapes
REFERENCES:
patent: 4955208 (1990-09-01), Kawashima et al.
patent: 5564065 (1996-10-01), Fleck et al.
McKane Elizabeth
Tao Inc.
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