Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1998-08-26
2001-10-23
Niland, Patrick D. (Department: 1714)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C522S008000, C522S033000, C524S359000, C524S394000, C524S401000, C524S503000
Reexamination Certificate
active
06306932
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an anti-fogging coating material which is capable of imparting hydrophilicity and the function of absorbing water to the surfaces of substrates, such as optical lenses, spectacles and window glass of vehicles, which require anti-fogging properties and the prevention of dew condensation, and the surfaces of films for bubble-jet printers, and forming a water-insoluble film having a high surface hardness, an anti-fogging coating film formed out of the anti-fogging coating material, and an anti-fogging article on which the anti-fogging coating film has been formed.
2. Related Background Art
The reason why substrates such as glass and plastics fog up is that moisture in the air adheres thereto in the form of fine waterdrops because their surface temperatures are lowered to a dew point or lower, and so light is irregularly reflected on the surfaces of the substrates. Accordingly, it is considered that the occurrence of fogging can be prevented by preventing the formation of waterdrops on the surfaces of the substrates. As such anti-fogging methods, for example, four factors of (A) adjustment of wetting; (B) impartment of water-absorbing properties; (C) impartment of water repellency; and (D) adjustment of humidity by heating have been considered.
With respect to the factor (A), anti-fogging sprays and the like are on the market for the purpose of adjusting wetting, namely, making a contact angle between a substrate and a waterdrop small. However, such a spray uses a surfactant or the like, so that the durability of its effect is not good.
With respect to the factor (B), the water-absorbing properties is an effect brought about by a coating film of a hydrophilic polymer, and the durability of the effect is somewhat good when compared with the anti-fogging spray. However, a substrate to the surface of which the water-absorbing properties have been imparted by such a coating film fogs up when exceeding the water absorption capacity of the coating film, and the surface begins to dissolve.
With respect to the factor (C), the water repellency is imparted by applying a water-repellent compound to a substrate. When the water-repellent compound is applied to, in particular, the inside surface of a vinyl plastic hothouse, fine waterdrops on the surface come into contact each other and fall as bigger waterdrops, whereby anti-fogging properties can be developed. However, fine waterdrops may adhere to the surface in some cases, resulting in the occurrence of fogging.
With respect to the factor (D), the adjustment of humidity by heating can achieve an anti-fogging effect on lenses of copying machines, rear windshields for automobiles and high-grade dressing tables. Since a power source is required, however, its application fields are limited.
Further, the films formed out of an anti-fogging coating composition comprising an organic polymer containing a surfactant have been developed. This anti-fogging coating composition is so designed that the film formed is made hydrophilic by polyether polyol in the presence of the surfactant to absorb moisture, and wetting is adjusted by the surfactant contained when the moisture exceeds the critical point of water absorption of this film, thereby retaining good transparency. Since the surfactant is easily dissolved in water and dissolved out, however, the anti-fogging properties and strength of the film are markedly lowered.
Japanese Patent Application Laid-Open No. 8-231944 discloses that the drawbacks involved in the conventional methods are improved by using polyalkylene oxide and a polyacrylic as organic polymers, and making use of a three-dimensional structure formed by the hydrolysis and polycondensation reaction of an inorganic alkoxide. However, a problem arises after immersion in water for a long period of time and upon use at a low temperature, and so there is a tendency not to sufficiently develop its performance.
SUMMARY OF THE INVENTION
The present invention has been made to solve the above-described drawbacks involved in the prior art, and its object is to provide a coating material for providing a anti-fogging coating film which is hydrophilic and water-insoluble and has high water absorbing power and excellent surface hardness, and in particular, an anti-fogging coating material for enhancing surface precision in the coating and light transmission properties of optical lenses and the like.
Another object of the present invention is to provide an anti-fogging coating film formed out of the coating material described above and an anti-fogging article on which the anti-fogging coating film has been formed.
The above objects can be achieved by the present invention described below.
The present invention provides an anti-fogging coating material comprising at least one selected from the group consisting of an inorganic alkoxide, a hydrolysate of the inorganic alkoxide and a polycondensate of the hydrolysate of the inorganic alkoxide, a polyacrylic, and polyvinyl alcohol.
The present invention provides an anti-fogging coating film formed by using, as a main component, a composition obtained by the polycondensation reaction of a hydrolysate of an inorganic alkoxide in the presence of a polyacrylic and polyvinyl alcohol.
The present invention provides an anti-fogging coating film formed by using, as a main component, a composition obtained by the polycondensation reaction of a hydrolysate of an inorganic alkoxide in the presence of a polyacrylic, polyvinyl alcohol and hydrosilicofluoric acid.
The present invention provides an anti-fogging coating film formed by using, as a main component, a composition obtained by the polycondensation reaction of a hydrolysate of an inorganic alkoxide in the presence of a polyacrylic, polyvinyl alcohol, hydrosilicofluoric acid and a silane coupling agent having an epoxy group.
The present invention yet further provides an anti-fogging coating film formed by using, as a main component, a composition obtained by the polycondensation reaction of a hydrolysate of an inorganic alkoxide in the presence of a polyacrylic, polyvinyl alcohol and a specific benzophenone compound.
The present invention yet still further provides an anti-fogging article obtained by providing any one of the aforementioned anti-fogging coating films on the surface of a substrate.
The anti-fogging coating films obtained by using the anti-fogging coating material according to the present invention combine excellent anti-fogging properties with high insolubility, abrasion resistance and weather resistance which are required of anti-fogging coating films. Such a phenomenon that the anti-fogging properties is developed on the anti-fogging coating films according to the present invention is considered to be as follows. The polyacrylic and polyvinyl alcohol are generally soluble in water or an alcoholic solvent. However, the polyacrylic and polyvinyl alcohol contained in the anti-fogging coating films according to the present invention do not dissolve out even when the films are immersed in water or the alcoholic solvent. The reason is considered to be due to the fact that when a hydrolysate of an inorganic alkoxide undergoes the polycondensation reaction, it also reacts with the coexisting polyacrylic and polyvinyl alcohol to form a complex polymer having an inorganic moiety derived from the inorganic alkoxide and an organic moiety having hydrophilic groups derived from the polyacrylic and polyvinyl alcohol. Further, the hydrophilic groups of the complex polymer effectively orient, whereby moisture or water from the outside can be absorbed greatly and quickly.
The hydrolysis of the inorganic alkoxide and the polycondensation reaction subsequent thereto are called a sol-gel processing reaction such that an inorganic alkoxide is subjected to hydrolysis and polycondensation reaction in its solution to convert the solution into sol in which fine particles of an inorganic oxide or inorganic hydroxide are dissolved, and the reaction is further allowed to proceed to form gel
Ikari Hatsumi
Ikemori Keiji
Ohtaka Keiji
Ukuda Hideo
Yamamoto Tohru
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Niland Patrick D.
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