JP2001074902A - Antifogging film and optical parts - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an anti-fogging film having anti-fogging properties and to embody excellent chemical resistance, scratch resistance and water resistance by forming a thin film consisting of a metal compound on a film which is formed on a substrate and has water absorption properties. SOLUTION: This anti-fogging film has a film 5 formed of a water absorptive polymer 2 and an inorganic polymer 3 on the glass substrate 1 and granular silica 4 is further dispersed into the film 5. The surface of the film 5 further has a metallic compound thin film 6 formed of a porous metal compound. The organic/inorganic hybrid film consisting of the water absorptive polymer 2, the fine particulate silica 4 and the inorganic polymer 3 is formed by mixing prescribed materials and curing the mixture by heating. The metal compound thin film 6 is formed on the film 5 having the water absorption properties to impart the durability to the film for improving the anti-fogging properties formed on the substrate. Such film species include titanium oxide, silicon oxide, zircon oxide, hafnium oxide, tantalum oxide, magnesium fluoride, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the production of an antifogging film having excellent scratch resistance, water resistance and chemical resistance.

[0002]

2. Description of the Related Art Glass has been widely used in window glasses, automobile windshields, and spectacle lenses, as well as optical components such as lenses, mirrors, and prisms. However, as a disadvantage of having transparency, when the surface temperature is lower than the dew point temperature of the atmosphere, or when the atmosphere becomes hot and humid, fine water droplets condense and hinder the transmission of light, So-called clouding occurs.

[0003] Many attempts have been made to impart anti-fogging properties. In general, as a principle of anti-fogging, there are a method utilizing the wettability of the solid surface with water and a method of preventing dew water from adhering to the surface. The following methods (a) and (b) can be used to utilize the wettability of the solid surface with water. (A) A method for preventing water droplets as the surface becomes hydrophilic with a surfactant or the like. (B) A method for preventing water droplets due to water repellent treatment of the surface.

The following (c) and (d) are methods for preventing dew water from adhering to the surface. (C) A method of absorbing dew condensation below the surface by providing a water absorbing film on the surface. (D) Heating the surface to keep the temperature above the dew point to prevent condensation.

[0005] The anti-fogging method can be classified into three types, (A) bulk modification, (B) surface modification, and (C) structural method, according to the processing technology. Among them, many studies on (B) surface modification have been made since the antifogging property can be imparted only to the surface without impairing the properties of plastic or glass. However, the requirements for anti-fog properties are not uniform and vary depending on the application and the place where it is used.

[0006] By the way, a lens of an optical device such as a camera becomes fogged when its surface temperature falls below the dew point. This clouding is because moisture in the atmosphere adheres as fine water droplets and is irregularly reflected. In such an optical device, the place where the fogging is most likely to occur and the performance of the device is likely to be affected by the fogging is an outermost optical component such as a lens which is most likely to come into contact with the outside atmosphere. But,
Since such optical parts are exposed to the outside, there are demands for scratch resistance, chemical resistance, water resistance, etc. in addition to anti-fogging properties and optical properties, and an anti-fogging method that satisfies all of the current conditions has been developed. It has not been.

[0007]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an anti-fogging film and an optical component which have anti-fogging properties and are also excellent in chemical resistance, scratch resistance and water resistance. The purpose is to provide.

[0008]

According to a first aspect of the present invention, there is provided a film formed on a surface of a substrate, the film having a water absorbing property formed on the substrate, and a film formed on the substrate. And a thin film made of a metal compound formed thereon. As described above, by forming a thin film made of a metal compound having excellent water resistance, chemical resistance, and friction resistance on a film that absorbs condensed moisture, the above-mentioned problem could be solved.

Further, in the first embodiment of the present invention, the thickness of the thin film is set to 10 Å to 200 Å. With such a range,
The thin film has an island structure and has a structure having many holes and the like. Moreover, such a thin film is strong, and the holes formed in the thin film are minute, so that many molecules and structures larger than water do not reach the water-absorbing film. Can prevent the coating from being damaged.

The thin film is made of magnesium fluoride. As a film formed on the film, among the metal compounds, magnesium fluoride is water-resistant, chemical-resistant,
Excellent friction resistance. By the way, in the second embodiment of the present invention, an optical component having a film having a water-absorbing polymer on an optical element and a thin film made of a metal compound formed on the film is provided.

As described above, a film obtained by heating and curing a water-absorbing polymer and an organosilicon compound or a hydrolyzate thereof is formed on the surface of a component used as an optical component as a substrate. By forming a thin film made of a metal compound on the surface, an optical element having antifogging properties, and further excellent in water resistance, chemical resistance, and friction resistance can be obtained.

Next, the present invention will be described in detail with reference to embodiments. However, the present invention is not limited to this embodiment.

[0013]

Next, an optical element having anti-fogging properties according to an embodiment of the present invention will be described. The optical element having the anti-fog property has a sectional structure of the concept as shown in FIG. This optical element is provided on a glass substrate 1.
Coating 5 formed of water-absorbing polymer 2 and inorganic polymer 3
It has. In addition, this film 5 further includes granular silica 4
Are distributed. The surface of the film 5 further has a metal compound thin film 6 formed of a porous metal compound.

The coating 5 is an organic-inorganic hybrid film composed of the water-absorbing polymer 2, fine-particle silica 4 and the inorganic polymer 3, as can be seen from FIG.
This organic-inorganic hybrid film is formed, for example, by mixing the following materials and curing by heating. First, materials to be mixed to form the organic-inorganic hybrid film in the embodiment of the present invention are as follows:
At least one material selected from the materials classified into the classes (b), (c), and (d) is used. First, the substances of the classification of (a) are used. First, they constitute substances corresponding to the water-absorbing polymer 2, and polyacrylic acids and polyvinyl alcohol are used. Examples of the polyacrylic acids include polyacrylic acid, polymethacrylic acid, polyacrylamide, and salts thereof. The average molecular weight of the polyacrylic acids is from 2,000 to 500,00
0, particularly preferably 5,000 to 250,000. Polyvinyl alcohol has an average degree of polymerization of 250 to 3,000.
0, polyvinyl alcohol having a saponification degree of 70 mol% or more is used. Particularly, an average polymerization degree of 500 to 1,000 and a saponification degree of 80 to 95 are preferably used. When the saponification degree is 70 or less, there is a problem in the antifogging property, and when it is 95 or more, the solubility in water is poor.

Next, as a material of the class (b), there is a particulate silica having an average particle diameter of about 5 to 200 nm.
As the material of the class (c), the general formula is R1R2aSi
The organic silicon compound represented by (OR3) 3-a or a hydrolyzate thereof is classified. As a specific example, β-
Glycidoxyethyltrimethoxysilane, β-glycidoxyethylmethyldimethoxysilane γ-glycidoxypropyltriethoxysilane, β-glycidoxypropyltrimethoxysilane, β-glycidoxyethylmethyldimethoxysilane, β-gly Sidoxyethylmethyldiethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, β-glycidoxyethylethyldimethoxysilane, γ-glycidoxyethylmethyldimethoxysilane,
γ-glycidoxypropylethyldiethoxysilane, β
-Glycidoxypropylethyldiethoxysilane, β-
Glycidoxyethylpropyldimethoxysilane, β-
(3,4 epoxycyclohexyl) ethyltrimethoxysilane, β- (3,4 epoxycyclohexyl) ethyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane , Vinyltrimethoxyethoxysilane, γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, γ-chloropropyltripropoxysilane, γ-chloropropyltributoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane,
3,3,3-trifluoropropyltrimethoxysilane,
γ-methacryloxypropyltrimethoxysilane, dimethyldimethoxysilane, γ-chloropropylmethyldimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, and the like. These compounds can be used alone or in combination of two or more.

Finally, materials classified into (d) include:
For the purpose of accelerating the curing, various catalysts known as silanol condensation and silanol hydroxyl reaction catalysts are used. N, N-dimethylbenzylamine, aluminum chelate compounds, especially aluminum acetylacetonate, are preferred. The above-mentioned materials are mixed and stirred at an appropriate ratio, and the liquids having the respective concentrations uniformed are coated on the glass substrate 1. Then, by heat-curing in an oven, a water-absorbing film 5 of an organic-inorganic hybrid film is formed.

However, the film 5 alone has antifogging properties, but it is difficult to balance the water absorbing effect and the film hardness. By increasing the proportion of the material classified in (a), a film having sufficient antifogging properties can be obtained, but water resistance,
The scratch resistance is inferior. Further, by increasing the proportion of the materials classified into (b) and (c), a film having excellent water resistance and abrasion resistance is obtained, but the antifogging property is inferior.

Therefore, a metal compound thin film 6 was formed on the water-absorbing film 5 for the purpose of imparting the durability of the film formed on the substrate for improving the anti-fogging property. Examples of the film type of the metal compound thin film 6 include titanium oxide, silicon oxide, zircon oxide, hafnium oxide, tantalum oxide, and magnesium fluoride (MgF2). When the substrate to be formed is used as an optical component, the substrate is selected from materials capable of forming a transparent optical thin film.

Generally, these types of metal compound thin films 6
Is deposited on the substrate 1 by a sputtering method, a vacuum deposition method, or an ion plating method. Further, by performing heating film formation at the time of forming the metal compound thin film 6, film durability such as solvent resistance is improved. In order to increase the film durability without impairing the anti-fogging property, it is necessary to control the thickness of the metal compound thin film 6 to be in the range of 10 to 200 Å. When the film thickness is reduced to a range from 10 Å to 200 Å, a so-called island structure is formed in the thin film. The metal compound thin film 6 having the island structure does not transmit water droplets attached to the surface, but water droplets of a micro size such as water vapor can sufficiently pass through the film 5 below the metal compound thin film 6. . Therefore,
Water droplets such as water vapor are not condensed on the surface of the metal compound thin film 6 and are absorbed by the film 5 and do not impair the anti-fogging effect. When the film thickness is less than 10 angstroms, the film 5
When swells, it is difficult to form a film exhibiting sufficient durability. Therefore, the thickness is preferably 10 Å or more.

By the way, when magnesium fluoride formed by a vacuum deposition method is used for such a metal compound thin film 6,
It is easy to achieve both durability and anti-fogging property, and it is more effective.
Further, since magnesium fluoride has a low refractive index, there is an advantage that an effect as an antireflection film can be obtained. Also, in normal use, to remove dirt attached to the surface,
It is expected to wipe with tissue paper, handkerchief, etc. This wiping will damage the film 5 alone, but by forming the metal compound thin film 6 on the film 5, it will not be damaged at all and the abrasion resistance effect will be improved.

The film 5 and the metal compound thin film 6
As an optical element provided with, an eyepiece lens of a camera or the like is preferable. Also, by providing the lens inside the lens barrel of the camera lens, it is possible to suppress the fogging inside the lens. In particular, when it is desired to form an anti-fog film on a portion that slides in the lens barrel, as described in the embodiment of the present invention, the film 5
When the metal compound thin film 6 is provided, the effect can be maintained while suppressing the fogging inside the lens. In addition,
When the film 5 or the metal compound thin film 6 is formed on the lens barrel, the substrate is a lens barrel.

In the present invention, a water-absorbing film is formed by the above-mentioned mixed solution. However, the present invention is not limited to this, and a water-absorbing film obtained from a different material may be used as a thin film made of a metal compound. May be used to obtain chemical resistance, water resistance, and scratch resistance. Hereinafter, the present invention will be described in more detail with reference to Examples.

[0023]

EXAMPLES Next, the antifogging film according to the present invention will be specifically described with reference to examples. First, a film having antifogging properties is formed on the substrate 1. For this purpose, a coating liquid capable of forming a film was prepared. First, polyvinyl alcohol (manufactured by Wako Pure Chemical Industries, polymerization degree: about 900 to 1,100, saponification degree: 86.0 to 90.0 mo)
1%), weigh 60 g, add pure water to a beaker, and add 600 g
g of solution was prepared. This solution was immersed in hot water of 80 to 90 degrees Celsius and stirred with a stirrer for about 2 hours to obtain a colorless and transparent 10% aqueous solution of polyvinyl alcohol.

Next, 20 g of γ-glycidoxypropyltrimethoxysilane was weighed into a beaker, and 4.57 g of 0.01 N hydrochloric acid was gradually added thereto while stirring with a stirrer to effect hydrolysis. After completion of the hydrolysis, the product was stored in a refrigerator for one day to obtain a hydrolyzate, and a hydrolyzate of γ-glycidoxypropyltrimethoxysilane was obtained. Then, 1 g of a hydrolyzate of γ-glycidoxypropyltrimethoxysilane and 30 g of methanol silica sol (solid content 30 to 31%, average particle diameter 10 to 20 nm) were added to 600 g of the produced polyvinyl alcohol aqueous solution. 0.24 g of aluminum acetylacetonate was added to this solution, mixed well with stirring, and filtered with a 3 μ filter to obtain a coating solution for coating a glass substrate.

Next, the glass substrate which has been washed in advance is set on a spin coater, and the coating liquid is dropped while paying attention not to cause bubbles. 1,300 rpm. p.
m for 15 seconds to coat the entire surface of the glass substrate. Thereafter, the coated glass substrate was heated in a clean oven at 130 degrees Celsius for 30 minutes. After the heating, the film was taken out of the oven and cooled at room temperature to obtain a colorless and transparent waterproof film 5.

The thickness of the film 5 thus formed was about 1.5 μm. The anti-fogging property of the film 5 was not fogged even when the film 5 was kept in a thermostat at 0 ° C. for 30 minutes and then transferred to a thermostat at 25 ° C. and 85% relative humidity. Next, the glass substrate 1 on which the film 5 is formed is set on a rotating dome above the vacuum evaporation apparatus. Granular magnesium fluoride is set on a molybdenum boat, which is an evaporation source for resistance heating, or on a hearth for electronic heating.

Next, the inside of the evaporation apparatus is evacuated with a vacuum pump, and the pressure is reduced to 1.33 × 10 −3 Pa. The power of the heater provided above the rotating dome is turned on, and the glass substrate 1 on which the film 5 is formed is heated to 250 ° C. When the temperature reaches, vapor deposition is started, and when 40 Å is adhered, the shutter is closed and the power of the heater is turned off. After cooling for about 5 minutes, the valve is gradually opened to return the inside of the evaporation apparatus to the atmosphere. By taking out from the vacuum evaporation apparatus, a glass substrate having a magnesium fluoride film formed on the film 5 was obtained.

The following tests were attempted on the obtained glass substrates. Antifogging property: The antifogging film formed above was kept in a thermostat at 0 ° C. for 30 minutes and then transferred to a thermostat at 25 ° C. and a relative humidity of 85%. As a result, no fogging occurred. Chemical resistance: When wiped with methanol, ether or the like, there was no problem at all. Water resistance: When a drop of water was dropped with a dropper and wiped with tissue paper, there was no problem at all.

Scratch resistance: When rubbed 20 times with a 500 g load using Kyoka Paper, no scratch was observed.

[0030]

As described above, according to the present invention, a metal compound thin film is formed on a water-absorbing film to form a film having excellent anti-fog properties such as water resistance and scratch resistance. it can. Further, when a magnesium fluoride thin film is used as the metal compound thin film, a film having better scratch resistance is formed.

Further, by controlling the thickness of the metal compound thin film to 10 Å or more and 200 Å or less, a thin film layer having an island structure is formed without impairing the water absorption performance of the underlying water-absorbing film. Thus, the durability of the entire film formed on the substrate could be improved.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of an optical element according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Glass substrate 2 ... Water-absorbing polymer 3 ... Inorganic polymer 4 ... Granular silica 5 ... Coating 6 ... Metal compound thin film

Claims (4)

[Claims] 1. A coating film formed on a surface of a substrate, comprising: a coating film formed on the substrate and having water absorbency; and a thin film made of a metal compound formed on the coating film. Anti-fog coating. 2. The antifogging film according to claim 1, wherein the thickness of the thin film is not less than 10 angstroms and not more than 200 angstroms. 3. The antifogging film according to claim 1, wherein the thin film is made of magnesium fluoride. 4. An optical component comprising, on a surface of an optical element, a film having a water-absorbing polymer and a thin film made of a metal compound formed on the film.