JPH06114992A - Formation of ultraviolet barrier film - Google Patents

Abstract

PURPOSE:To form a UV barrier film absorbing all of UV rays within a required wavelength region and not generating the lowering of absorbing capacity and discoloration with the elapse of time on an object to be coated composed of a transparent material. CONSTITUTION:At first, a film 1 composed of first coat containing titanium oxide with a particle size of 0.1mum or less and a film 2 composed of second coat containing an org. UV absorber are applied to the surface of an object to be coated so that the film 1 composed of the first coat is positioned on the side exposed to UV rays.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating film of an ultraviolet absorbing paint on the surface of an article to be coated, which is made of a plate-shaped or other shaped article made of a substantially transparent material such as glass or synthetic resin. The present invention relates to a method for forming an ultraviolet blocking film, which comprises forming.

[0002]

2. Description of the Related Art Conventionally, ultraviolet absorbing paints have been used in the construction industry, food industry, agriculture and other industries. Among them, in the construction industry, on the surface of window glass of buildings such as houses and hotels,
In order to improve the living environment, it has been practiced to apply a UV-absorbing paint that produces a transparent coating film to cut off UV rays. In addition, in the food industry, in order to prevent discoloration and deterioration of food and other products on sale in the shop window, a UV absorber is applied to the outer shell and cover of the lighting equipment.
It is common practice to illuminate products for sale and exhibits through this coating film. Further, in agriculture, a UV absorber is applied to the surface of a synthetic resin film spread in a vinyl house, and the growth of plants is promoted by receiving sunlight through the resulting coating film.

That is, all the coated objects to which these paints are applied are made of a transparent material, and the ultraviolet rays are cut off, but the light rays of other wavelengths need to pass therethrough. Therefore, the coating film formed on the surface thereof. It needs to be almost transparent.

Conventionally, as an ultraviolet absorbing paint for obtaining this transparent coating film, in the organic system, a vehicle prepared by dissolving a synthetic resin or the like in an aromatic or aliphatic organic solvent is used.
A benzophenone-based, benzotriazole-based, salicylate-based, or substituted acrylonitrile-based ultraviolet absorber dissolved or dispersed is used. In the case of an inorganic type, similarly, a vehicle in which an inorganic oxide such as zinc oxide or titanium oxide is dispersed is used.

[0005]

However, among the above-mentioned conventional ultraviolet absorbing paints, those using an organic ultraviolet absorber generally have a tendency that the ultraviolet absorbing ability thereof decreases in proportion to the amount of ultraviolet exposure. However, this is because the ultraviolet absorber itself is deteriorated by ultraviolet rays, and there is a problem in durability.
In order to improve this, it has been attempted to mix a light stabilizer, an antioxidant and the like into the paint, but the remarkable effect has not been obtained.

Generally, ultraviolet rays have an upper limit of 360 to 400 nm, which is the short wavelength end of visible light, and a lower limit of about 1 nm.
Up to 300 nm, but the wavelength region to be absorbed as an ultraviolet absorber is 300 to 400 nm. By the way, the lower limit of the ultraviolet wavelength that can be absorbed by this organic ultraviolet absorber is up to about 350 nm, and the absorption wavelength range is limited. In addition, in order to increase the absorption effect, even if the amount mixed is increased, the compatibility or dispersibility in the binder is not good, so the concentration in the paint is low, and as a result, it is necessary to increase the thickness of the coating film. In addition to being restricted by the above, since the coating film turns yellow with time and the transparency is lowered, there are various problems such as not being able to be used for window glass or the like which is particularly required to have transparency.

On the other hand, those using an inorganic ultraviolet absorber are generally excellent in durability against ultraviolet rays, but there are still restrictions on the wavelength range in which absorption is possible. Looking at the typical one, FIG. 4 is a graph showing the total light transmittance of the inorganic ultraviolet absorber for each wavelength.
Shows the case of zinc oxide, and the same figure (b) shows the case of titanium oxide.

That is, in the case of zinc oxide, the upper limit is 360 nm.
If this is exceeded, the absorption capacity will become extremely poor. In addition, the ultraviolet ray having a wavelength range of 305 to 360 nm also has an insufficient absorption capability as a whole. In the case of titanium oxide, the upper limit is 360 nm. In order to improve this, if the amount of inorganic oxide is increased, the coating becomes cloudy and the transparency is reduced. Cannot be used for.

As a result of various studies, the present inventor has found that this problem can be solved by incorporating the advantages of both organic and inorganic ultraviolet absorbers, and has completed the present invention. .

That is, the present invention solves the above-mentioned drawbacks of the prior art, has no restriction on the wavelength range that can be absorbed, absorbs light rays in the required wavelength range evenly, and has a reduced absorption capacity over time. The present invention has been made for the purpose of providing a "method for forming an ultraviolet blocking film" by which a coating film which is not colored or markedly colored can be obtained.

[0011]

DISCLOSURE OF THE INVENTION The present invention provides a method for forming an ultraviolet blocking film, which comprises coating an ultraviolet absorbing paint on the surface of an article to be coated which is made of a substantially transparent material. A coating film made of a first coating material containing titanium oxide having a particle diameter of 0.1 μm or less and a coating film made of a second coating material containing an organic ultraviolet absorber are formed on the surface of
In addition, "the method for forming an ultraviolet blocking film, characterized in that the coating film made of the first coating material is positioned on the side exposed to the light rays".

That is, in the method of forming an ultraviolet blocking film according to the present invention, titanium oxide is adopted as an inorganic ultraviolet absorber, and the coating composed of this ultraviolet absorber is used as the first coating, and various organic ultraviolet absorbers are used. The paint containing the agent is used as the second paint, both paints are applied to the object to be coated to form a coating film, and the physical properties which are not sufficient for each other are complemented, and should be absorbed. Expansion of the wavelength range of ultraviolet rays,
The purpose is to improve the durability of the coating film.

The "subject to be coated made of a substantially transparent material" in the present invention does not refer to a specific molded article, but includes all molded articles formed of a substantially transparent material and to which an ultraviolet absorbing coating is to be applied. Of course, as described above, it is often targeted mainly at window glass of buildings, show windows, plastic film of vinyl houses and the like. In addition, the surface of these coated objects is, for example, in the case of a window glass, both front and back surfaces are referred to as "surfaces", and does not necessarily refer to only outer surfaces. Further, the formation of the ultraviolet blocking film is performed at least on the surface on which the ultraviolet deterioration is to be prevented, and depending on the material, it may not be the entire surface of the coated object.

In the present invention, the reason why titanium oxide is selected as the inorganic ultraviolet absorber instead of zinc oxide is that the upper limit is 360 nm in the case of zinc oxide, and if it exceeds this, the absorption capacity is extremely poor. Become. Also, 305
This is because the absorption capacity is generally insufficient for ultraviolet rays in the wavelength range of up to 360 nm, while in the case of titanium oxide, the upper limit is 360 nm.
This is because the ability to cut ultraviolet rays in the wavelength range of 60 nm is sharp.

Titanium oxide has a particle size (= average particle size) of 0.1 μm or less, preferably 0.05.
It is necessary to use one having a thickness of μm or less. If it exceeds 0.1 μm, the transparency of the coating film may be impaired. Further, the content of the titanium oxide particles when mixed and dispersed in the coating material is preferably in the range of 0.1 to 5 parts by weight with respect to 100 parts by weight of the dry coating film. If it exceeds 5 parts by weight, cloudiness of the coating film tends to occur, and if it is less than 0.1 part by weight, the ultraviolet absorbing ability becomes insufficient. Preferably, it is 0.5 to 2 parts by weight, and if it is within this range, it is easy to balance the total visible light transmittance, the ultraviolet ray cut ratio, and the like.

In the present invention, various known organic UV absorbers such as benzophenone-based, benzotriazole-based, salicylate-based, and substituted acrylonitrile-based UV-absorbers can be used as the organic UV-absorbent used in the second coating material. Specifically, as the benzophenone type, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-
Examples thereof include dimethoxybenzophenone. Further, as a benzotriazole type, 2- (2'hydroxy-
5'-methylphenyl) benzotriazole, 2-
(2'hydroxy-3 ', 5'-di-t-butylphenyl) benzotriazole, 2- (2'hydroxy-
3 ', 5'-di-t-amylphenyl) benzotriazole and the like can be mentioned. Also, as salicylates,
Examples include phenyl salicylate, p-t-butylphenyl salicylate, p-octylphenyl salicylate, and the like.
Further, examples of the substituted acrylonitrile system include 2-ethylhexyl-2-cyano-3,3'-diphenyl acrylate.

The content is 0.01 to 5 parts by weight, preferably 0.05 to 1 part by weight with respect to 100 parts by weight of the vehicle.
It may be part by weight. If the amount is less than 0.01 parts by weight, the intended function cannot be exhibited, and even if the amount is more than 5 parts by weight, the compatibility or dispersibility with the binder is originally poor, so that the effect is not exerted and the yellowing occurs. Problems such as are likely to occur.

Further, in the present invention, if a small amount of a light stabilizer, an antioxidant, etc. is mixed with the organic ultraviolet absorber,
A product with slightly superior durability can be obtained. The organic ultraviolet absorbers can be used alone or in admixture of two or more.

The above-mentioned first coating material containing titanium oxide and the second coating material containing an organic ultraviolet absorber, which are used in the present invention, are both known ones. Based on the completely new idea of using these two types of paints, these two types of paints are applied to at least the surface of the substrate to be protected from ultraviolet deterioration to form an ultraviolet blocking film. An important feature is that the procedure is performed.

Usually, the ultraviolet absorbing paint is often applied to the back side surface of the article to be coated, not the front side surface (for example, the outside surface in the case of window glass), to form a coating film. The main reason for this is that the transparent body such as glass itself has a small amount of ultraviolet absorbing ability, so that the ultraviolet absorbing ability of this glass reduces the exposure dose of the ultraviolet absorber and prolongs its life. However, in the present invention, the case where it is applied to both surfaces through which the light ray of the article passes, or the case where it is applied only to the front surface is included. However, according to the present invention, whichever side is applied, the first side is exposed on the side exposed to light rays such as sunlight.
Must be formed so that the coating film of is located. For example, when forming an ultraviolet blocking film on the back side of the window glass,
The first coating film is formed first, and then the second coating film is formed on top of it. By doing so, deterioration of the organic ultraviolet absorber, which is less durable than the inorganic ultraviolet absorber, is prevented.

In the present invention, the method of forming the coating film using the first or second coating material is not particularly limited, and any known method can be used, and the portion to be coated on the object to be coated can be used. The most suitable coating method may be selected and adopted based on factors such as the area, the area, the vehicle component, and the set coating speed. In addition, it is not always preferable that the second coating film formation be performed after the first coating film formation is completed (= after complete drying), and the second coating film may be overcoated depending on the constituent components of the coating material. From the viewpoints of securing the adhesive strength at the laminated interface, the speed required for forming the ultraviolet blocking film, and the like, it may not be possible to say unequivocally because it may be preferable to perform it during the drying process.

[0022]

The method for forming an ultraviolet blocking film of the present invention is, in the range of a limited ultraviolet absorption wavelength, on the surface of an article to be coated,
A first coating containing an inorganic ultraviolet absorber using titanium oxide, which has a sharp absorption capacity, and a second coating containing an organic ultraviolet absorber, to form a multi-layered coating film. Therefore, in the ultraviolet rays passing through this coating film, all the ultraviolet rays in the wavelength range of 300 to 400 nm which should be absorbed are absorbed, and there is no blank wavelength region which is not absorbed.

Further, since the coating film made of the first coating material is formed on the side exposed to the light rays, the coating film made of the second coating material passes through the coating film made of the first coating material. It will absorb a small amount of ultraviolet light.

[0024]

EXAMPLES Examples of the present invention will be described below. Preparation of coating material 1 A vehicle having 55 parts by weight of an acrylic resin and 45 parts by weight of an organic solvent mixed at a ratio of toluene: methyl ethyl ketone = 1: 1 has an average particle diameter of 0.04 μm.
m 1.5 parts by weight of titanium oxide was added, and the mixture was mixed and dispersed using a ball mill for 24 hours, and then the obtained dispersion liquid was centrifuged to remove the aggregated titanium oxide, and only the supernatant liquid was taken out to obtain coating 1 And

Preparation of paint 2 A vehicle composed of 55 parts by weight of an acrylic resin and 45 parts by weight of an organic solvent mixed at a ratio of toluene: methyl ethyl ketone = 1: 1 was used for a benzotriazole ultraviolet absorber (Harima Chemicals). Company name, product name: Harisorp 20
44) Paint 2 is a mixture of 0.5 part by weight and 0.5 part by weight of light stabilizer.

EXAMPLE As shown in FIG. 3 (a) as a sectional view, 10 parts of the paint 1 was applied on a washed glass plate 3 having a thickness of 3 mm and a size of 100 mm square.
cc was dropped, and coating and drying were performed using a bar coater to obtain a coating film 1 having a uniform film thickness and an average thickness of 5 μm. Next, after confirming that the coating film 1 has been dried by checking by touch, 10 cc of the coating material 2 is dropped on the coating film 1,
Similarly, coating and drying were performed using a bar coater to obtain a coating film 2 having a uniform film thickness and an average thickness of 5 μm, and an ultraviolet blocking film 4 was formed together with the coating film 1 to obtain a sample 1.

Comparative Example 1 Comparative Sample 1 was prepared in the same manner as in Example 1 except that the amount of the coating material 1 used was 20 cc, the film thickness thereof was 10 μm, and the coating material 2 was not used. Comparative Example 2 Comparative Sample 2 was prepared in the same manner as in Example 1 except that the amount of the coating material 2 used was 20 cc, the film thickness thereof was 10 μm, and the coating material 1 was not used.

With respect to the sample 1 and each comparative sample obtained in the above-mentioned examples and each comparative example, characteristic tests were conducted for each item of turbidity and total visible light transmittance. The test results are shown in Table 1. The above test methods are as follows. Turbidity; the ratio of the intensity of scattered light and the intensity of incident light when light passes through a substance, which is an index of transparency. A turbidimeter NDH manufactured by Nippon Denshoku Industries Co., Ltd. was used for the measurement. Total visible light transmittance; parallel transmittance (%) at the time of turbidity measurement, which is an index of transparency.

[0029]

[Table 1]

From the results of the above characteristic test, Comparative Example 1 consisting of only the coating material 1 having the same film thickness was poor in both turbidity and total visible light transmittance, and was used for an object to be coated made of a transparent material. Although not possible, it is understood that these points are considerably improved in the case of the embodiment in which the paints 1 and 2 are used in combination. On the other hand, an exposure test was conducted on the separately prepared Sample 1 and Comparative Samples 1 and 2 in the following manner.

That is, as shown in FIG. 3B, the surface on which the ultraviolet blocking film 4 is formed is the inside, and the blue test paper 5
And the same glass plate 6 as the glass plate 3 are stacked in this order, and caulking with silicon (not shown) is performed in order to prevent the intrusion of water into each sample, and this is subjected to an exposure tester (Suga Test Instruments Co., Ltd., Product name: Sunshine WM tester)
In contrast, the glass plate 3 side was set so that the irradiation surface side was exposed to UV light for 2000 hours continuously, and all light rays of each wavelength of Sample 1 and Comparative Samples 1 and 2 before and after the exposure test were exposed. The transmittance (= ultraviolet absorption rate) was measured and the result is shown in Fig. 1.
The graphs are shown in (a) to (c). FIG. 1A shows the sample 1, FIG. 1B shows the comparative sample 1, and FIG.
Are graphs for Comparative Sample 2, in which the upper part shows the wavelength range of 300 to 800 nm, and the lower part shows the wavelength range of 300 to 400 nm.

On the other hand, with respect to Sample 1 and each comparative sample, changes in color difference of the blue test paper due to irradiation were measured, and the results are shown in a graph in FIG. In addition, the determination of the color difference change is shown in Table 2 below.
The sensory evaluation was performed based on the evaluation criteria shown in.

[0033]

[Table 2]

From the results shown in FIG. 1, it is clear that the durability and ultraviolet ray cut performance of Sample 1 are considerably superior to those of the comparative sample. That is,
From the viewpoint of durability, the decrease in the ultraviolet absorbing ability before and after the exposure test is due to only the inorganic ultraviolet absorbing paint, Comparative Example 1
Is comparatively excellent, but in the case of Comparative Example 2 containing only the organic ultraviolet absorbing paint, its ability is almost lost after exposure, whereas in the case of Sample 1, it is 300 to 360 n.
Within the range of m, it does not decrease at all, and within the range of 360 to 380, there is almost no decrease, and only above 380, the decrease is recognized. Moreover, it is clear that the data after this exposure also have a significant difference compared to the case of Comparative Example 1. The results shown in FIG. 1 are also supported by the color difference change graph shown in FIG.

[0035]

Industrial Applicability The method of forming an ultraviolet blocking film of the present invention comprises an inorganic material using titanium oxide, which exhibits a sharp absorption capability within a limited ultraviolet absorption wavelength range with respect to the surface of a substrate. A first coating material containing a system ultraviolet absorber and a second coating material containing an organic ultraviolet absorber are used to form a multi-coated coating film. Therefore, it is possible to absorb ultraviolet rays passing through this coating film. 300-400nm which is the wavelength range that should be
All of the ultraviolet light during the period will be absorbed, and there will be no blank wavelength region that will not be absorbed.

Therefore, with respect to the ultraviolet rays from the light source, all the ultraviolet rays in the wavelength range to be absorbed are blocked, and the ultraviolet ray cutting function which surely exhibits the ultraviolet ray cutting function in the wide range of wavelengths which cannot be realized by the conventional ultraviolet absorbers is obtained. To be Further, since the coating film made of the first coating material is formed on the side exposed to the light rays, the coating film made of the second coating material is a small amount of ultraviolet rays which have passed through the coating film made of the first coating material. Will be absorbed.

Therefore, the life of the organic UV absorber itself, which has been conventionally considered to be relatively poor in durability and has not been markedly improved by adding a light stabilizer or an antioxidant, is remarkably extended. In addition, it is possible to obtain a highly durable UV-cutting function in a wide wavelength range, which has a synergistic effect with the coating film made of the first coating material.

[Brief description of drawings]

FIG. 1 (a) is a total light transmittance (= ultraviolet ray) of each wavelength of Sample 1 and Comparative Samples 1 and 2 before and after an exposure test for an example of an ultraviolet blocking film obtained by the forming method of the present invention. Absorption rate), which is 300 to 8 in the upper row.
The wavelength range of 00 nm is shown, and 300 to 4 are shown in the lower row.
The wavelength range of 00 nm is shown. (B) and (C) are graphs similarly showing the measurement results for the conventional example obtained under the same conditions.

FIG. 2 is a graph showing measurement results of change in color difference of blue test paper with irradiation for Sample 1 and Comparative Samples 1 and 2 before and after the test used in the exposure test shown in FIG.

FIG. 3A is a cross-sectional view showing an example of the ultraviolet blocking film obtained by the forming method of the present invention, and FIG. 3B is when performing an exposure test of the ultraviolet blocking film obtained by the forming method of the present invention. FIG. 3 is a cross-sectional view for explaining the relationship between the structure of the sample and the irradiation direction.

FIG. 4 is a graph showing the total light transmittance of an example of a conventional ultraviolet blocking film for each wavelength of ultraviolet rays.

[Explanation of symbols]

 1 Coating film made of the first paint 2 Coating film made of the second paint 3,6 Glass plate 4 UV blocking film 5 Blue test paper UV UV

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification number Office reference number FI technical display location B05D 7/24 303 B 8720-4D C09D 5/32 PRB 7211-4J

Claims (1)

[Claims] 1. A method for forming an ultraviolet blocking film, which comprises coating an ultraviolet absorbing coating on the surface of an article to be coated which is made of a substantially transparent material, wherein the surface of the article has a particle size of 0. A coating film composed of a first coating material containing titanium oxide of 1 μm or less and a coating film composed of a second coating material containing an organic ultraviolet absorber are formed to overlap each other, and a coating film formed on the side exposed to light rays 1. A method for forming an ultraviolet blocking film, characterized in that a coating film composed of the paint 1 is positioned.