JPH06127980A - Coating solution for forming ultraviolet absorption film and formation of ultraviolet absorption film - Google Patents

Abstract

PURPOSE:To prevent the generation of crack by applying a coating solution containing a zinc organic acid compound and CeO2 superfine particle as main components on a transparent substrate and firing at a specific temp. to form an ultraviolet absorption film. CONSTITUTION:(A) solution is prepared by dissolving a specific quantity of zinc organic acid compound such as zinc ethylhexanoate in a solvent such as butanol. And (B) solution is prepared by dispersing a specific quantity of CeO2 particulate having 5-10mum particle diameter to butanol or the like. Next, (A) solution and (B) solution are mixed with each other so as to be 0.05-2.0 CeO2/ZnO by weight ratio after firing and are sufficiently stirred to form the coating solution. After that, by applying the coating solution on the transparent substrate so as to be a prescribed film thickness and firing at >=300 deg.C, the transparent ultraviolet absorption thick film free from crack is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ultraviolet absorbing film used for a window glass, a cover of a halogen lamp or the like.

[0002]

2. Description of the Related Art It is important to shield ultraviolet rays entering a room or the inside of a vehicle in order to prevent not only sunburn of a human body but also deterioration of ornaments in the room or the vehicle.

Further, halogen lamps and metal halide lamps, which are widely used in fields where high brightness is required, such as recent automobile headlamps, generate strong ultraviolet rays due to their light emitting characteristics. Removal by filters is becoming essential.

Conventionally, organic compounds such as benzophenone and benzotriazole have been mainly known as ultraviolet absorbers, but these organic compounds have a problem that they tend to be deteriorated due to absorption of ultraviolet rays. Then
There is also a problem that it cannot be used in a high temperature part such as a lamp cover. Further, an ultraviolet absorbing film using zinc oxide, which is known as an inorganic compound and has a high ultraviolet absorbing performance, is obtained by dissolving an organic acid zinc compound in an organic solvent, coating it on a substrate, and then baking it. It is known that

However, in this method, there is a problem that not only organic zinc oxide is decomposed and volatilized during firing to be easily whitened, but also cracks are easily formed when a thick film is formed at once. . In order to prevent whitening, a method of adding an unsaturated fatty acid such as linoleic acid or irradiating with ultraviolet rays has been effective, but an effective method has not been found in terms of thickening the film.

[0006]

DISCLOSURE OF THE INVENTION The present invention solves the above-mentioned drawbacks when forming an ultraviolet absorbing film by thermal decomposition of a zinc organic acid compound, and provides a highly transparent ultraviolet absorbing film. Moreover, it aims at providing the coating liquid which can form a thick film at once.

That is, the present invention is a coating liquid containing an organic acid zinc compound and cerium oxide ultrafine particles as main components,
And a method of forming an ultraviolet absorbing film by applying the coating solution on a transparent substrate and then baking at a temperature of 300 ° C. or higher.

In the coating liquid of the present invention, the cerium oxide ultrafine particles not only act as an ultraviolet absorber, but also serve to relieve the tensile stress inside the film at the time of firing and suppress the generation of cracks when a thick film is applied. Have Furthermore, the addition of cerium oxide ultrafine particles has the effect of suppressing volatilization of the organic zinc salt during firing, resulting in a highly transparent coating film. It is considered that this is because cerium oxide, which is ultrafine particles having a large surface energy, plays some catalytic role during thermal decomposition.

The cerium oxide ultrafine particles used in the coating liquid of the present invention preferably have a particle size in the range of 5 nm to 100 nm. If the particle size is less than 5 nm, the ultraviolet absorbing ability is poor and the function as an internal stress relieving agent becomes small, which is not preferable, and if the particle size exceeds 100 nm, the transparency may be impaired when a film is formed. Further, even if cerium oxide having a small particle size is used, the agglomeration in the liquid may still adversely affect the transparency. Therefore, various surfactants may be used to dissolve the cerium oxide in the organic solvent.

The organic acid zinc compound used in the coating solution of the present invention is not particularly limited as long as it becomes zinc oxide by heat. However, in view of easiness of film formation, adhesion, transparency, etc. Zinc hexanoate is relatively preferably used.

The amount of cerium oxide in the coating solution is CeO ₂ / ZnO = weight ratio of zinc oxide and cerium oxide after firing.
It is preferably 0.05 or more and 2.0 or less. If the amount of cerium oxide is less than this, the internal stress cannot be effectively relaxed and cracks easily occur, and if more than this, the coating becomes colored yellow.

[0012]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[Example 1] Zinc ethylhexanoate (Zn
10 g (content 18%) was added to 22.4 g of 1-butanol and dissolved (solution A). 15 g of cerium oxide ultrafine particles having an average particle size of 8 nm (trade name: Nidral manufactured by Taki Chemical Co., Ltd.) were dispersed in 85 g of butanol (B).
liquid).

9 g of solution A and 1 g of solution B were mixed and well stirred, and then soda lime glass having a thickness of 2 mm (ultraviolet transmittance 70%, visible light transmittance 90%) was applied at 500 rpm for 5 seconds using a spin coater. It was applied and baked at 500 ° C. for 5 minutes. The film-coated glass obtained was transparent, had no cracks, and had an ultraviolet transmittance of 7% and a visible light transmittance of 90% (film thickness 6500Å).

[Example 2] An ultraviolet absorbing film was obtained in the same manner as in Example 1 except that the liquid obtained by mixing the liquids A and B of Example 1 in equal amounts (weight) was used as a coating liquid. The film-coated glass obtained was transparent, had no cracks, and had an ultraviolet transmittance of 10%,
The visible light transmittance was 90% (film thickness 4900Å).

Comparative Example An ultraviolet absorbing film was obtained in the same manner as in Example 1 except that the solution A of Example 1 was used as it was as a coating solution. The obtained film was whitened and many cracks were generated. Moreover, the film had a very poor adhesiveness, which was easily removed by rubbing with a finger.

[0017]

As described above, according to the present invention, a transparent ultraviolet absorbing film can be simply obtained by adding ultrafine particles of cerium oxide to an organic acid zinc compound, and a thick film can be formed without cracks. Since it can be applied, the productivity is greatly increased.

Claims (3)

[Claims] 1. A coating liquid for forming an ultraviolet absorbing film, which contains an organic acid zinc compound and cerium oxide ultrafine particles as main components. 2. After applying the coating liquid according to claim 1 on a transparent substrate,
A method for forming an ultraviolet absorbing film, which comprises forming the ultraviolet absorbing film by firing at a temperature of 300 ° C. or higher. 3. The method for forming an ultraviolet absorbing film according to claim 1, wherein the organic acid zinc compound is zinc ethylhexanoate.