Coating processes – Direct application of electrical – magnetic – wave – or... – Polymerization of coating utilizing direct application of...
Reexamination Certificate
2000-01-19
2002-01-01
Cameron, Erma (Department: 1762)
Coating processes
Direct application of electrical, magnetic, wave, or...
Polymerization of coating utilizing direct application of...
C427S517000, C427S387000, C427S412100
Reexamination Certificate
active
06335061
ABSTRACT:
Method of making coating layers containing photocatalyst and a photocatalyst coating film formed thereby
FIELD OF THE INVENTION
The present invention relates to a method of making photocatalyst contained coating layers to provide a film which is improved in the resistance to fouling, the durability, and the transparency while having a photocatalytic function, and to a photocatalyst coating film formed by the method.
BACKGROUND OF THE INVENTION
It has lately been desired to provide a coating composition for forming a coating which is improved in the resistance to climate, the resistance to fouling, and the resistance to chemicals while being high in the physical hardness. It is also anticipated that such compositions should be arranged favorable for common use. Some conventional compositions composed mainly of a silyl-based vinyl resin and an organosilane compound are disclosed in Japanese Patent Laid-open Publications (Hei)01-69673 and (Hei)01-69674 where fundamental materials for making coatings are limited. Also, similar inventions are disclosed in Japanese Patent Laid-open Publications (Hei)04-108172 and (Hei)04-117473 where fundamental materials are widely selected but their details for coating performances are not definitely described.
Organosilane coating materials have technically been developed for use as maintenance-free coating materials which are advantageous for the resistance to climate (and sunlight), fouling, and so forth. The demand for improving the performance of organosilane coating materials is overwhelmingly increased. Therefore, it is now desired to provide coating materials which are improved in the coating appearance, the adhesivity, the resistance to climate, heat, alkalis, organic chemicals, moisture, and (hot) water, the insulating property, the abrasion resistance, the resistance to fouling, and so forth and are thus capable of forming a coating of a higher hardness.
Particularly for improving the resistance to fouling, it is known to make the surface of a coating hydrophilic. For example, the addition of a hydrophilic material or a water-soluble material is proposed. However, such a hydrophilic material or a water-soluble material may gradually be deteriorated when exposed to light and washed away with water, hence failing to maintain the level of hydrophilic property of the coating at the surface throughout a duration of service time.
Also, a variety of coating components including photocatalytic materials have been provided. One of them is, for example, a component for making a photocatalytic titan oxide coating composed mainly of titan oxide, hydrolyzate of a hydrolytic silicon compound (alkyl silicate or silicon halogenide), and a solvent (water or alcohol) (See Japanese Patent Laid-open Publication (Hei)8-164334). Another is a component treated at the surface for providing anti-bacteria and anti-mycotic properties and comprising a silicon compound having at least two alkoxy groups, a titan or zirconium compound having at least two alkoxy groups, and a hydrophilic non-organic powder e.g. of titan oxide processed with alkoxysilane and/or polysiloxane having at least two alkoxy groups (See Japanese Patent Laid-open Publication (Hei) 8-176527). Moreover, a method is known for making a non-organic coating by producing a coating from a liquid mixture of a powder having a photocatalytic function and containing a non-organic paint which is prepared from 20 to 200 parts by weight of tetra-alkoxysilane, 100 parts by weight of tri-alkoxysilane, and from 0 to 60 parts by weight of dialkoxysilane and of which the weight-average molecular weight based on polystyrene is higher than 900 and processing the coating with an acid or an alkali (See Japanese Patent Laid-open Publication (Hei)8-259891).
However, the compositions for making a coating and the liquid mixture are intended only to provide anti-bacterial and anti-mycotic properties, remove odors, and decompose toxic substances in the alkoxysilane and/or polysiloxane containing a photocatalyst and a guanidyl group. In addition to the above, the above mentioned arts fail to specify totally the essential characteristics of the resultant organosilane coating including the hardness, the adhesivity, and the resistance to alkalis, organic chemicals, climate, and fouling.
Further disclosed are a composition adapted for use as a cog composition which satisfies the requirements for performance of an organosilane coating material and composed mainly of a partial condensate of organosilane, an aqueous dispersion of colloidal silica, and a silicon-modified acrylic resin (See Japanese Patent Laid-open Publication (Sho)60-135465), a composition composed mainly of a condensate of organosilane, a chelate compound of zirconium alkoxide, and a hydrolytic silyl-based vinyl resin (Japanese Patent Laid-open Publication (Sho)64-1769), and a compound composed mainly of a condensate of organosilane, a colloidal alumina, and a hydrolytic silyl-based vinyl resin (See U.S. Pat. No. 4,904,721).
However, coatings made of the compositions disclosed in (Sho)60-135465 and U.S. Pat. No. 4,904,721 have the disadvantage that their glittering property may be declined when they are exposed to ultraviolet light for a considerable length of time. Also, the composition disclosed in (Sho) 64-1769 is low in the storage stability; it may easily be turned to gel within a short period of time when its solid density is increased.
We, the inventors, have invented a composition for coating which includes a hydrolyzate and/or a partial condensate of organosilane, a vinyl resin having a silyl group containing silicon atoms bonded with a hydroxy group and/or a hydrolyzate, a metallic chelate compound, &bgr;diketone and/or &bgr;-ketoester (See Japanese Patent Laid-open Publication (Hei)5-345877). While our composition has a favorable balance over the coating characteristics required for any organosilane coating material, more improvement of the coating characteristics shall be required.
Moreover, a self-cleaning film having a surface layer provided on a film substrate and containing substantially transparent particles of a photocatalytic oxide is disclosed in Japanese Patent Laid-open Publication (Hei)9-227161. The film may however be deteriorated by the effect of photocatalytic actions as being doubtful in the long-term durability. Also, a photocatalytic sheet having a photocatalytic coating formed on its upper surface and provided at its lower surface with an adhesive coating for attaching to another device or material to offer a photocatalytic function is disclosed in Japanese Patent Laid-open Publication (Hei)9-313887. Similarly, the sheet may however be deteriorated by the effect of photocatalytic actions as being doubtful in the long-term durability.
SUMMARY OF THE INVENTION
The present invention has been invented in view of overcoming the foregoing technical drawbacks of the prior arts and its object is to provide a method of making photocatalyst contained coating layers to provide a film which is improved in the resistance to fouling, the durability, and the transparency and has a photocatalytic function while the coating is easily applied on an organic film substrate, and provide a photocatalyst coating film produced by the method.
The method of making photocatalyst contained coating layers, according to the present invention, comprises the steps of providing a coating layer of the composition (i) or (ii) on the surface of an organic film and providing a coating layer of the composition (I) or (II) on the coating layer, wherein:
the composition (i) is a coating composition containing at least one component (a) selected from organosilanes, hydrolyzates of the organosilanes, and condensates of the organosilanes represented by Formula 1
(R
1
)
n
Si(OR
2
)
4−n
(1)
(wherein, R
1
is a monovalent organic group having 1 to 8 carbon atoms: when two exist, they are either identical to or different from each other; R
2
is an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 6 carbon atoms: when two exist, they are either
Kanamori Tarou
Sakagami Toshinori
Shimada Mibuko
Cameron Erma
JSR Corporation
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