Stock material or miscellaneous articles – Composite – Of quartz or glass
Reexamination Certificate
1998-03-09
2002-11-19
Nakarani, D. S. (Department: 1773)
Stock material or miscellaneous articles
Composite
Of quartz or glass
C428S141000, C428S142000, C428S448000, C428S450000, C428S451000
Reexamination Certificate
active
06482524
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a substrate of glass, ceramics, plastic, or metal, etc., having a treatment surface, i.e., a water repellent coating or film being formed on an undercoating layer or film thereof, and a treatment method therefor.
2. Description of Related Art
Conventionally, a substrate comprising for example glass or the like, on the surface of which a water repellent coating, layer or film is formed, has been already known, in for example, Japanese Patent Publication No. Hei 4-20781 (1992), Japanese Laid-open Patent No. Hei 5-86353 (1993), Japanese Laid-open Patent No. Hei 5-161844 (1993), Japanese Laid-open Patent No. Hei 2-311332 (1990) and Japanese Patent No. 2,525,536.
In Japanese Patent Publication No. Hei 4-20781 (1992), it is disclosed that on the surface of the substrate there is formed a coating layer or film from a silane compound excluding polyfluoro radicle or synthetic resin, and further thereon is formed a water repellent and oil repellent multi-layer coating or film comprising a silane compound including polyfluoro radicle.
Further, in Japanese Laid-open Patent No. Hei 5-86353 (1993), there is disclosed a method by which a thin film of siloxan radicle is formed on the surface of glass, ceramics, plastic, or metal, etc., by use of a compound including chlorosilyl radicle, such as SiCl
4
, in molecular form thereof, and further thereon is formed a chemical absorption unimolecular accumulation layer or film (a water repellent film or coating).
Also in Japanese Laid-open Patent No. Hei 5-161844 (1993), there is described a method in which, having formed a unimolecular film of siloxan radicle or an absorption film of polysiloxan previously, the chemical absorption unimolecular film (a water repellent film or coating) is formed on the surface of a substrate by a further chemical absorption processing conducted in an atmosphere including a surface-active agent of chlorosilane radicle.
Moreover, Japanese Laid-open Patent No. Hei 2-311332 (1990) describes a water repellent glass obtained through silylating the surface of glass substrate by a silyl compound, such as fluorinated alkylsilane, the surface of which is formed from a metal oxide, such as SiO
2
.
Furthermore, Japanese Patent No. 2,523,536 discloses that an undercoating film or layer of silica is applied on the glass substrate before treating the surface thereof by the fluorine compound, in the same manner as described in Japanese Laid-open Patent No. Hei 2-311332 (1990), and further that weather resistance of the water repellent film is improved by including olefin telomer in the fluorine compound.
With the substrate which can be obtained by the method disclosed in Japanese Patent Publication No. Hei 4-20781 (1992), since the density of the undercoating layer is low, the undercoating layer must be more than 100 nm in thickness thereof and also the temperature for baking must be higehr than 400° C.
In the method disclosed in Japanese Laid-open Patent No. Hei 5-86353 (1993), since the absorbent for the reaction to water in air is unstable, it is necessary to maintain the humidity in the atmosphere low, thereby control of the environment being difficult. Further, there are problems, in that it takes 2-3 hours for the treatment, and the nonaqueous solvent is expensive.
For implementation of the method which is disclosed in Japanese Laid-open Patent No. Hei 5-161844 (1993), equipment for controlling the atmosphere must be large-scaled, and it takes time to form a perfect absorption film.
With the substrate which is obtained by the method disclosed in Japanese Laid-open Patent No. Hei 2-311332 (1990), since baking at 500° C. for instance is necessitated for obtaining the high density metal oxide layer when forming the metal oxide film through a sol-gel method, also large-scaled equipment for baking the substrate at high temperature is necessary, thus raising the production cost. Further, having tried this method, the roughness of the metal oxide film thereby obtained is relatively high, resulting that it is difficult for water drops present on the surface of the water repellent glass to roll freely thereon.
Furthermore, with the substrate which is obtained by the method disclosed in Japanese Patent No. 2,525,536, though being superior with respect to weather resistance, such a result is only obtained through double-checking thereof that the durability of the water repellent film in a friction test is not adequate, and it is also difficult for water drops present on the surface of the water repellent glass to roll freely thereon since the roughness of the surface of the silica undercoating layer or coating is relatively high.
SUMMARY OF THE INVENTION
For resolving the drawbacks in the conventional art mentioned above, according to the present invention, there is provided a substrate having a treatment surface, characterized in that, on a surface of a substrate of glass, ceramics, plastics or metal, an undercoating film layer is formed by drying a liquid for undercoating treatment which is obtained by dissolving and reacting a material having chlorosilyl radicle in molecular form therein within an alcohol group solvent, so that on said undercoating film layer there is formed a water repellent or oil repellent layer, wherein a surface roughness (Ra) of said surface layer is equal to or less than 0.5 nm.
Further, the surface roughness (Ra) of the surface layer is preferably to be as small as possible. However, for example, the surface roughness (Ra) of a fire polished surface of float glass (i.e., upper surface of the float glass floating on molten tin) is about 0.2 nm, and the roughness (Ra) of a glass surface obtained through precise grinding is about 0.1 nm. Therefore, the substantially lowest threshold value of surface roughness (Ra) of the glass surface which can be obtained is about 0.1-0.2 nm.
As mentioned above, the undercoating film or layer formed from the undercoating treatment liquid, which is obtained by dissolving and reacting the material having chlorosilyl radicle in molecular form therein within an alcohol group solvent, has high smoothness, and therefore, the surface layer formed on the undercoating film or layer also comes to have high smoothness (Ra≦0.5 nm), reflecting the smoothness of the undercoating layer, thereby obtaining a superior water repellent property, i.e., a high contact angle and a low critical inclination angle.
Here, it is possible to remove defects in appearance by keeping the surface of the substrate clean when forming the undercoating layer or film on it, and it is also possible to increase adhesive strength between the substrate surface and the undercoating film by activating the surface of the substrate. For example, even in a case where the glass substrate comprises an oxide, it is possible to form an active surface by grinding the surface to within 0.5 nm≦Ra≦3.0 nm using a grinding agent.
However, in the case where the roughness (Ra) of the substrate surface exceeds 3.0 nm, it is difficult to make the roughness (Ra) of the surface layer (the water repellent layer) less than 0.5 nm even if effecting the undercoating treatment thereon. Therefore, it is preferable that the roughness (Ra) of the substrate surface be equal to or less than 3.0 nm. Moreover, when the substrate is made of glass plate, transparency of the substrate can be maintained when the roughness (Ra) is within a range of 0.5 nm=Ra≦3.0 nm.
Further, in the case where hydrophilic radicle is poor in the surface of the substrate, it is preferable to conduct the surface treatment after treatment for hydrophilizing the surface, i.e., by treating the surface with plasma containing oxygen or treating under a corona discharge atmosphere, or alternatively, by irradiating ultraviolet light of a wavelength in the vicinity of from 200 to 300 nm onto the substrate surface in an atmosphere containing oxygen.
Further, according to the present invention, it is appropriate to restrict the concentration of the material having chlorosilyl radicl
Kamitani Kazutaka
Kobayashi Hiroaki
Sunada Takashi
Teranishi Toyoyuki
Yamamoto Hiroaki
Merchant & Gould P.C.
Nakarani D. S.
Nippon Sheet Glass Co. Ltd.
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