Composite material

Details Composite material Composite material

2002-02-20

2004-06-01

Cherry, Euncha (Department: 2872)

Optical: systems and elements

Protection from moisture or foreign particle

Humidity or temperature control

C359S507000

Reexamination Certificate

active

06742902

ABSTRACT:

TECHNICAL FIELD
The present invention relates to a composite material the surface of which is made to be hydrophilic or antifouling by forming a film layer containing a photocatalytic substance on a material surface of a substrate, a lens, a glass plate, a mirror, etc, improving the hydrophilicity or antifouling property of the material surface.
BACKGROUND ART
A technique, which keeps a surface of a material clean by forming a photocatalytic substance layer on a material surface, has been known. This technique enables removing dirt easily by decomposing dirt adhering to the material surface using a photocatalytic action of a photocatalytic substance layer provided on the material surface and by rinsing the material surface with water or the like.
As a composite material employing a material surface cleaning technique using such a photocatalytic substance layer, there was one which was proposed by Japanese Patent Laid-open No.H10-36144 applied for by this applicant. Its structure is described, referring to cross-sectional drawing FIG.
2
. In this, a surface is made hydrophilic by providing a SiO
2
film
6
porously on the surface of a base material
2
. A surface of a SiO
2
film
6
is originally hydrophilic, the hydrophilicity, however, is improved by making the surface porous. With a SiO
2
film
6
exclusively provided, hydrophilicity decreases with dirt adhering to the surface if it is exposed to the air for a long period of time. Accordingly, by providing a TiO
2
film
4
between a SiO
2
film
6
and a base material
2
, the photocatalytic decomposition action of the TiO
2
4
film is used to decompose dirt adhering to the surface of a SiO
2
film
6
and to keep the surface of a SiO
2
film
6
clean, maintaining the hydrophilicity.
FIG. 3
shows a graph indicating spectral reflectance characteristics in a visible region (380~780 nm) in a conventional structure shown in
FIG. 2
with a SiO
2
film thickness made at 10 nm and when a film thickness of a TiO
2
film
4
changes to 50, 100, 150, and 200 nm.
FIG. 4
shows a graph indicating spectral reflectance characteristics with like samples. As shown in FIG.
3
and
FIG. 4
, when a film thickness of a TiO
2
film
4
is 50 nm, relatively flat reflectance characteristics and transmittance characteristics were obtained, while the amplitude in reflectance increases with a film thickness of 100, 150, and 200 nm as wavelengths change.
Additionally, Table 1 shows initial contact angles and contact angles after being exposed to black light with an intensity of 1 mW/cm
2
for four hours when oil is applied onto each material surface of a TiO
2
film
4
, using samples prepared in a conventional structure shown in
FIG. 2
with a film thickness of 50, 100 or 150 nm similar to FIG.
3
and
FIG. 4
respectively.
TABLE 1
Contact Angle
TiO
2
Film
Initial Contact
after being exposed to
Thickness
Angle
black light
(in nm)
(in degree)
(in degree)
50
87.7
72.1
100
86.6
8.3
150
85.6
7.9
DISCLOSURE OF INVENTION
As can be seen from the results of Table 1, for a hydrophilic material using the above-stated photocatalytic substance, a photocatalytic substance film
4
with a film thickness of 100 nm or more is required to obtain a photocatalytic decomposition action to maintain hydrophilicity. As shown in
FIG. 3
, however, when a film thickness of a TiO
2
film
4
is 100, 150 or 200 nm, a coloring action takes place on a material surface due to increased amplitude occurring in spectral characteristics. This is because optical interference in a visible light region occurs at a TiO
2
film
4
due to formation of a thick TiO
2
film
4
. Thus, if the amplitude in spectral characteristics is large, the color tone of an original material surface is spoiled. Additionally, to provide a thick film thickness, more photocatalytic substance material is required.
The present invention has been realized in consideration of the above-mentioned points, to provide a composite material which can obtain sufficient antifouling properties or hydrophilicity even when a photocatalytic substance film is thinner than a conventional film. Thus an optical interference action in a photocatalytic substance is suppressed and an amount of a photocatalytic substance to be used is decreased.
The present invention possesses a base material, a transparent metal thin film provided on the surface of the base material, and a hydrophilic functional layer containing a photocatalytic substance provided on a surface of the transparent metal thin film. According to experiments conducted by inventors, it was found that, by providing a transparent metal thin film, a photocatalytic property improves. Due to this, because hydrophilicity or antifouling can be obtained even if a hydrophilic functional layer containing a photocatalytic substance is thinner than conventional layers, an amount of a photocatalytic substance to be used can be reduced. Additionally, by making a hydrophilic functional layer containing a photocatalytic substance thinner, optical interference in a hydrophilic functional layer containing the photocatalytic substance can be reduced and the color tone of a base material can be maintained.


REFERENCES:
patent: 5854708 (1998-12-01), Kamotsu et al.
patent: 0 820 967 (1998-01-01), None
patent: 10-036144 (1998-02-01), None
patent: 10-297436 (1998-10-01), None
patent: 10-329261 (1998-12-01), None
patent: 11-092146 (1999-04-01), None
patent: 2000-131513 (2000-05-01), None

Affiliated with

Also associated with

Rating

Composite material does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Composite material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Composite material will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-3344343