Anti-clouding article and its production

Description: TECHNICAL FIELD [Detailed description of the invention]

【0001】

[Industrial application field]

The present invention relates to lenses such as eyeglasses and cameras having antifogging performance, or articles such as window glass, car windshields, helmet shields, underwater glasses, mirrors used in bathrooms, and the like.

【0002】

[Conventional technology]

As a method of imparting antifogging performance to an article, various methods as described below have been conventionally adopted.

【0003】

A method of kneading a surfactant into the synthetic resin base material itself or copolymerizing a hydrophilic monomer to form a synthetic resin base material to impart antifogging performance is described in JP-A-51-107841, Spec. Kaisho 55-102632, Tokushu Sho 57-31735, JP A 58-160325, JP A 60-141727, JP A 61-114201, JP A 61-114202, JP A 62-2202, JP A. It is disclosed in 62-2203 and so on.

【0004】

A method of applying a coating having anti-fog performance to an article is also well known. Kaisho 55-750, JP-A 55-148283, JP-A 57-119973, JP-A-58-1688, Square Root 59-15473, Square Root 62-28986, Square Root 1-249818, Square Root 2-18048 , JP-A-2-173078, etc.

【0005】

The method shown above is intended to impart hydrophilicity and water absorption to the base material itself or a thick coating layer to achieve antifogging performance.

【0006】

As a method of directly imparting antifogging performance to an inorganic substance such as glass having poor water absorption, a method of treating the outermost surface to make it hydrophilic or hydrophobic, or a method of making the inorganic substance porous to have water absorption is available. Known, Japanese Patent Application Laid-Open No. 52-11321, Japanese Patent Application Laid-Open No. 53-56177, Japanese Patent Application Laid-Open No. 54-105120, Japanese Patent Application Laid-Open No. 60-210641, Japanese Patent Application Laid-Open No. 62-57484, Tokusho 1-58481, JP-A-2-22341, etc. It is disclosed in.

【0007】

Graft polymerization as a method of surface modification is disclosed in JP-A 1-230644, JP-A-2-38431, and JP-A-4-225301.

【0008】

In order to impart antifogging performance to articles, including the methods shown above, 1) make the base material water-absorbent. 2) Make the surface of the base material hydrophilic. 3) Make the surface of the substrate hydrophobic. 4) Raise the surface temperature of the article to prevent moisture in the air from condensing on the surface. The four methods have been proposed from the past, and various attempts have been made.

【0009】

[Problems to be Solved by the Invention]

However, the conventional method has the following problems.

【0010】

The method of imparting anti-fog performance to the resin base material itself or the resin coating layer can obtain sufficient anti-fog performance, but the hydrophilic / water-absorbent resin becomes soft when it absorbs water and is extremely scratched. It was easy. If this is used in a part where wear resistance is required, such as a spectacle lens, the optical characteristics deteriorate due to scratches, and it cannot be put into practical use. Further, there is a drawback that dirt in the air, such as cigarette smoke, is easily adsorbed and the optical article is colored.

【0011】

Further, the biggest drawback of these methods is that the outermost surface cannot be subjected to a surface treatment for improving optical properties such as an antireflection layer. An antireflection film that is widely used at present and has good performance is an antireflection film made of an inorganic substance, and an inorganic substance such as silicon oxide must have antifogging performance.

【0012】

As a method of imparting antifogging performance to the glass surface or the surface of an inorganic substance, there is a method of applying a commonly used surfactant to the surface, but there is a problem in durability and the surfactant is easily removed by water. Resulting in.

【0013】

In addition, there is a method of forming a thin film on the glass surface or the surface of an inorganic substance using a hydrophilic substance to achieve antifogging performance, but according to the prior art, the bond between those substances and the surface is weak, and they can be easily obtained. The antifogging performance could not be maintained for a long period of time due to the loss of the substance. Further, when hydrophilicity is imparted by exposing the hydroxyl group as in the conventional case, it is difficult to achieve both water resistance and discoloration resistance.

【0014】

On the contrary, when imparting hydrophobicity, a contact angle with water of about 180 ° is required to allow water droplets adhering to the surface to fall off. A complex of graphite fluoride and a metal is known as such a substance, but it has not been used for antifogging so far.

【0015】

In order to solve the above-mentioned problems, a method of treating the surface with a silane coupling agent and then reacting with a reactive surfactant has been proposed, but it is sufficiently prevented depending on the structure of the reactive surfactant. It was difficult to obtain the clouding effect and to prevent water burn.

【0016】

Therefore, the present invention solves the above problems and obtains an article having excellent antifogging performance such as durability, stain resistance, and water discoloration resistance without deteriorating the optical properties and abrasion resistance of the article. The purpose is.

【0017】

[Means for solving problems]

The anti-fog article of the present invention is an anti-fog article characterized in that a layer containing titanium oxide as a main component is provided on the surface of the article.

【0018】

As is well known, titanium oxide can undergo a photocatalytic reaction to convert light energy into chemical energy. When light with a wavelength shorter than 400 nm is absorbed by titanium oxide, the surface of titanium oxide exhibits strong oxidizing power, and various compounds are decomposed.

【0019】

Water is no exception and is decomposed. Therefore, if a layer containing titanium oxide as a main component is provided on the surface of an article, even if small water droplets are generated on the surface, the water droplets are instantly decomposed by the presence of ultraviolet rays, and the water droplets that cause fogging do not grow. ..

【0020】

The layer of titanium oxide may be titanium oxide alone, but when a metal such as platinum is added to form a small photoelectrochemical cell, the oxidizing power is further increased and the antifogging ability is also improved.

【0021】

The formation of the layer on the surface of the article can be performed by various methods. When forming a layer as a thin film, the thin film may be formed by vacuum deposition, sputtering, CVD, etc., or the thin film may be formed by a sol-gel method or a heat-curable hard coat containing ultrafine titanium oxide. it can. In any case, it suffices if a layer containing titanium oxide as a main component is formed on the surface of the article.

【0022】

Any article to which antifogging property is imparted may be used, but an optical article such as a lens, a mirror, a window, goggles, or underwater glasses is very effective in terms of application.

【0023】

[Example]

[Example 1] Immerse in a sodium hydroxide solution (0.1N) in advance, wash well with water, and apply the following coating solution to a dried diethylene glycol bisallyl carbonate lens by the dipping method so that the film thickness becomes 2.5 μm. , Heat cured at 130 ° C for 2 hours.

【0024】

(Adjustment of coating liquid) In a reaction vessel equipped with a stirrer, 206 g of ethanol, 396 g of ethanol-dispersed colloidal silica (Oscar 1232 solid content 30% manufactured by JGC Catalysts and Chemicals Co., Ltd.), γ-glycidoxypropyltrimethoxy 312 g of a partial hydrolyzate of silane, 0.2 g of a flow control agent (L-7604 manufactured by JGC Catalysts and Chemicals, Inc.) and 86 g of a 0.05 N acetic acid aqueous solution were added, and the mixture was stirred at room temperature for 3 hours to prepare a coating liquid.

【0025】

The coated lens obtained as described above was set in a vacuum chamber, and the resin surface was subjected to antireflection treatment at a substrate temperature of 50 ° C. by a vacuum vapor deposition method. The film composition is the optical film thickness, from the lens side, the silicon dioxide layer is λ / 4, the combined film thickness of the zirconium oxide layer and the silicon dioxide layer is λ / 4, the zirconium oxide layer is λ / 4, and the uppermost silicon dioxide. The layer was λ / 4. (Here, λ is 520 nm) Next, a layer of titanium oxide was provided on this antireflection film by vacuum deposition for about 5 nm.

【0026】

The anti-fog property of the obtained article was evaluated in grades 1 to 4 according to the anti-fog property of the low temperature part of "JIS-S4030 Anti-fog test method for eyeglasses". (1st grade has the best anti-fog performance, 4th grade has the worst.) Natural light was made to exist in the constant temperature bath used. The evaluation results are shown in Table 1 together with Examples and Comparative Examples.

【0027】

[table 1]

<img file="JPH08313705A_D0001.tif" />【0028】

[Example 2] When the coating liquid was prepared in Example 1, 1 g of titanium oxide ultrafine particles (particle size 8 nm) was dispersed in ethanol-dispersed colloidal silica. Then, the coating liquid was applied to the diethylene glycol bisallyl carbonate lens in the same manner as in Example 1 and cured.

【0029】

[Example 3] After treating the surface of a normal soda glass plate with Ar plasma having an output of 400 W, TiCl is used by the optical CVD method.₄Was reacted with the surface. TiCl₄Shows an immobilization reaction with Si-OH on the glass surface. This immobilization reaction and water treatment were repeated 5 times to prepare an immobilized titanium oxide catalyst having 5 Ti-O-layers on the surface of soda glass.

【0030】

[Comparative Example] The sample before the uppermost titanium oxide layer was provided in Example 1 was used as a comparative example.

【0031】

[Effect of the invention]

According to the invention of claim 1, titanium oxide having a photocatalytic action is present on the surface of the article, and even if minute water droplets adhere to the surface due to temperature difference and humidity difference, they are immediately decomposed by natural light. Anti-fog can be achieved without the growth of water droplets that cause fog. Further, since titanium oxide itself is harder than the resin, the wear resistance of the article is not lowered even if it is used on the surface of the article. Further, since the titanium oxide layer has a photochemical reaction effect even if it is thin, it can be formed on the surface without significantly affecting the optical characteristics of antireflection.