JPH04204601A - Coating composition - Google Patents

Abstract

PURPOSE:To control a coating film to a desired value of refractive index and to prevent occurrence of a moire pattern by incorporating at least one of fine powders of magnesium fluoride, silicon oxide, and aluminum oxide each specified in particle diameter in titanium alkoxide. CONSTITUTION:This coating material composition contains titanium alkoxide and at least one of the fine powders of magnesium fluoride, silicon oxide, and aluminum oxide each having a particle diameter of <=0.1mum, and a refractive index of 1.52, 1.37, and 1.60, respectively, each lower than that of titanium oxide having a refractive index of 2.3-2.5 obtained by the titanium alkoxide, thus permitting the desired refractive index within 1.4-2.5 of the film to be obtained by mixing these fine powders or any 2 or only one of them with the titanium alkoxide.

Description

[Detailed Description of the Invention] [Industrial Field of Application] The present invention utilizes interference to form a light reflecting film for forming an anti-reflection film and for protecting optical substrates. - It relates to a coating composition used when forming a tocoat film.

1 Conventional technology I.

In order to reflect or transmit light through interference, it is necessary to form a film on the substrate with the thickness and refractive index required by the calculations.

Conventionally, the formation of a light reflecting film or an anti-reflection film was performed using S.
I O3, A Q + 03, 2 r O2, T I
By vacuum evaporating or sputter linking a film material such as O2 onto the substrate (vacuum film formation method), or by dipping (impregnating) the substrate in an alcoquid solution containing the metal component of the above film material.
This is then carried out by subjecting it to superheating treatment (dipping method).

In order to apply a heart coat to protect the optical substrate, it is necessary to form a heart coat film on the optical substrate with a refractive index close to that of the optical substrate.

Conventionally, the heart coat film has been formed using a vacuum film forming method or a dipping method, similar to the formation of the reflective film and the like.

1. As mentioned above in the invention or problem to be solved, in order to reflect or transmit light rays by interference, it is necessary to form a film on the substrate with the film thickness and refractive index required by calculation. There is. However, the film material 5iO7 used as a light reflecting film or an anti-reflection film
, A(lto3.Zrot and T!O7 have refractive indices of 1.46, 1.6, and 2.0°25, respectively, and each film material has a unique value.

Therefore, in order to obtain a film with a desired refractive index using a vacuum film forming method such as vacuum evaporation or sputtering, first, several components of the above-mentioned film materials are used in the same vacuum jar to obtain the desired refractive index. There is a technology that simultaneously vacuum evaporates and sputters a composite film material with a certain ratio.

However, even if the evaporation speed or Svanter speed is constant, each component during film formation is difficult to remain constant, and the rate of vacuum evaporation or sputtering differs. Therefore, it is difficult to obtain a film with a desired refractive index by such means. 1-Is there a method to form a multilayer film by vacuum evaporating or spun-linking the above film materials in layers?The refractive index of each layer required from the calculation is the refractive index of available phosphor, titania, alumina, and zirconia. Since there is a discrepancy between the two, the number of films has been increased to cope with this problem, and there is a problem of increased costs due to the increase in the number of steps. Also, is there a theoretically proposed method for anti-reflection by so-called inclined film deposition, in which the refractive index of the film is gradually changed from the surface of the film to the boundary between the film and the substrate? It is technically very difficult to form a sloped film, and it has not been done in practice. Furthermore, when a film is formed by a vacuum film forming method such as vacuum evaporation or sputter linking, there is a problem that the refractive index changes over time due to excess or deficiency of oxygen components in the film.

In addition, in order to obtain a film with a desired refractive index using the dipping method, several ALCOKIT solutions containing the metal components of the above-mentioned film materials are mixed and the solution composition is controlled to obtain the desired refractive index. It is also known to immerse the substrate in this solution and then subject it to heat treatment.

However, in this method, in the step of hydrolyzing the film-forming solution for dipping the substrate, there are differences in the hydrolysis of each alkoxide containing each metal component, and the precipitation rate of the hydrolyzate is also different. This results in non-uniformity, and the film composition after dipping also becomes non-uniform. Therefore, this method is also inappropriate for obtaining a film having a desired refractive index.

On the other hand, in order to apply a heart coat to protect the optical substrate, it is necessary to form a hard coat film on the optical substrate with a refractive index close to that of the optical substrate, as described above.
The refractive index of the film material conventionally used for heart coats is 15 or less and f2. However, recently, optical substrates with high refractive indexes have been manufactured, and the difference between the refractive index of this substrate and the hard coat film has become large, causing The problem is that the interference due to reflection increases, causing moiré patterns.

The present invention was made in view of the surface situation, and provides a simple method for producing a light reflecting film or anti-reflection film having a desired refractive index, and a hard coat film that does not produce a moiré pattern and has excellent hardness. An object of the present invention is to provide a coating composition that can be formed on a substrate or base material.

[Means for Solving the Problems] The present invention provides titanium alcokit, 9 fine powders of Macunium fluoride with a particle size of 0.1 μm or less, or 1 silicon oxide fine powder with a particle size of 0.1 μm or less. A coating composition comprising at least one of the fine aluminum oxide powders, the solids in the coating composition described in 1. The above problem is solved by monodispersing the fine powder, which accounts for 3 to 90% by weight.

The thin film obtained by coating and thermally decomposing the titanium Alcokit is transparent, has excellent film strength, and exhibits a high refractive index of 23 to 2.5. From this, the inventor came to the idea that by blending transparent fine powder with a refractive index of less than 25 with this titanium alkoxide, it would be possible to create a paint that could continuously change the refractive index, and conducted various experiments. The coating composition of the present invention has been invented.

In the coating composition of the present invention, as described above, a transparent fine inorganic powder having a refractive index lower than 2.5 is used as a filler. This is because if the filler in such a coating composition is an organic substance, it cannot withstand the heating temperature (150° C. or higher) necessary for thermally hydrolyzing titanium alkoxide. Therefore, as fillers, we selected industrially available fine magnesium fluoride powder, fine silicon oxide powder, and fine aluminum oxide powder with a particle size of 0.1 μm or less. When the particle size of these fine powders exceeds 0.1 μm, diffuse reflection is strong due to Rayleigh scattering and the film becomes opaque, making it unsuitable for use in antireflection coatings. Also, the particle size is O,1
If it is less than μm, the secondary aggregation is very strong, and if it is simply dispersed like a normal paint, the secondary aggregation remains and tends to become opaque.

Therefore, it must be monodisperse, that is, it must be sufficiently dispersed (+)1 that there is no secondary agglomeration. It should be noted that the reason why it has not been possible to produce paints whose refractive index can be changed continuously using this type of dispersion method is that ordinary pigments have a particle size of 1.
Since it exceeds .mu.m, it is a polycrystalline material, and the reflection from the boundary surfaces of each crystallite is large, making it opaque, making it impossible to use it as a reflective film that requires transparency.

In normal dispersion of fine powder, there is no effective measuring method to check whether secondary agglomeration remains.1 First, the dispersion is carried out for as long as empirically considered to be sufficient to make it transparent. Check that there is no secondary aggregation. However, when dispersing fine magnesium fluoride powder, fine silicon oxide powder, and fine aluminum oxide powder with a particle size of 0.1 μm or less, the dispersion takes about 70 minutes, which is empirically considered to be sufficient. However, a clear dispersion was not obtained, and the above fine powder could not be considered as a transparent filler.

However, the present inventors have confirmed that the dispersion liquid of the fine powder can be made transparent by selecting a less aggressive dispersion treatment and carrying out the treatment more carefully and for a longer time than usual. For example, it was confirmed that the dispersion of the above-mentioned fine powder became transparent by conducting a dispersion treatment for a long period of time, which is empirically unthinkable (continuously for several weeks) using a sand mill, and it was confirmed that it became monodispersed by electric W4 observation. Make sure that the

Therefore, a coating composition containing fine magnesium fluoride powder, fine silicon oxide powder, and fine aluminum oxide powder with a particle size of 01 μm or less can be made transparent by performing a long-term strong monodispersion treatment. It can be used as a reflective film, an anti-reflective film, and a hard coat film.

Next, the preparation of the coating composition of the present invention will be explained in detail.

The coating composition uses titanium alkoxide as a binder, and in order to dilute the high refractive index of the resulting titanium oxide, it uses fluoride as a filler, which has a lower refractive index than titanium oxide, is transparent and heat resistant, and has a particle size of 0.1 μm or less. Either one of magnesium fine powder, silicon oxide fine powder, or aluminum oxide fine powder is blended, or two of the above three fine powders are mixed together, or preferably three of the above three fine powders are blended. It is characterized by mixing and blending all the fine powders and uniformly dispersing these fine powders.

Titanium alfuxite includes metquin group, ethoxy group,
Although it is within the scope of the present invention to use the propochyne group and their isomers, the etquine group is most preferred from the standpoint of safety, industrial ease, and cost, followed by the metquine group.

In order to improve film strength by using such alfuxite in paints, hydrochloric acid is usually added to stabilize it.
Partial hydrolysis of alfuxite is a known common technique and does not give any particular meaning to the technical idea of the present invention, but is within the scope of the present invention. Furthermore, if the above-mentioned fine powder with a particle size of 0.1 μm or less is added to this partially hydrated 5) 1 solution, or if the particle size is 0.1 μm or more, visible light is likely to be diffusely reflected, resulting in an increase in haze and the film cannot be used as an optical interference film.

In the above fine powder, the refractive index of magnesium fluoride is 1.37, the refractive index of silicon oxide is 1.52, and the refractive index of aluminum oxide is 1.60, all of which are titanium oxide obtained from titanium alkoxide. refractive index of 23
Since the refractive index is lower than 1.4 to 25, if these fine powders of magnesium fluoride, silicon oxide, and aluminum oxide are added alone or in a mixture to titanoalcokit by adjusting the amount, the refractive index will be lower than 1.4 to 25. A film with a desired refractive index can be obtained.

Further, the amount of the fine powder added as the filler is 3 to 90% by weight based on the titanium alkoxide. This is because if the amount added exceeds 90% by weight, the spaces between the fillers can be sufficiently filled with bindu, resulting in a decrease in the strength of the r' film. This is because if it is less than 3% by weight, the effect of the refractive index of the filler becomes smaller than the change in refraction and refractive index caused by the film forming conditions, so that it becomes meaningless.

The titanoalcokit and the filler described above are added to the coating composition of the present invention, and a solvent is further added. The appropriate type and amount of this solvent to be added to the paint composition is determined based on the adhesion with the substrate to be coated, compatibility with fillers and Pygoo, and the viscosity required for the paint. . However, this criterion is based on techniques known to those skilled in the art and need not be special.

Note that the solvent for alcohols is generally two selected from alcohols, and from the viewpoint of safety and industrial handling, ethanol is common.

With alcoquid paints, a film is formed by heating and hydrolysis, so add a small amount of an acid, for example, hydrochloric acid and water as a stabilizer, or use the usual techniques of those skilled in the art that are used for this method. It is enough.

The coating composition according to the present invention can be made by uniformly dispersing the above formulation, but the optical interference film according to the present invention contains 0.
．． Because it is often kept below +71m, it becomes cloudy, dirty,
Since the l\is must not be -・, it is necessary to completely monodisperse all the primary particles. Since I don't know of a direct and completely reliable way to measure monodispersion, I avoid dispersing it enough times until it disappears. The dispersion method is not particularly limited and any known technique may be used; however, as mentioned above, it is impossible to make the dispersion transparent with normal short-term dispersion, and from the viewpoint of efficiency, Ll is naturally powerful. It is preferable to use a dispersion method that requires a longer time than usual.

As a painting method, a known painting method can be used.
It is also within the scope of the present invention to use the method described above.

However, since the coating film thickness is required to be as thin as 0.1 μm, dipping, spin code, gravure coating, bar code, etc. are generally used.

Further, as long as the drying temperature of the coating film is 120° C. or higher, which is necessary for drying titanium alkoxide, a known film forming method for alkokid paint can be applied.

Since the coating film of the present invention is made of titanium alkoxide, it is possible to obtain a film with very strong film strength even if the above-mentioned filler is added.

"Effect 3 The coating composition of the present invention blends and disperses at least one fine powder of macawium oxide fine powder, fine silicon oxide powder, and fine aluminum oxide powder of 1 grain or less than 0.1 μm in titanoalcokit. Because it is a paint that has a high refractive index, it can be applied to substrates using methods such as Disopinok, Spinco, Clavia printing, etc., and a transparent and high-strength film can be obtained.Also, it contains fine powder with a lower refractive index than titanium oxide. By changing the type of fine powder, the mixing ratio of the fine powder in the mixture of these fine powders, and the amount of these fine powders or the mixture of fine powders added, it is possible to improve the quality of the optical interference film. A refractive index of between 14 and 25 can be produced.

π Example] "Experiment example 1".

After mixing 23 parts by weight of tetraethoquinotitanium as titanium alkoxide, 8 parts by weight of water and 0.1 part by weight of hydrochloric acid,
Partially hydrolyzed by heating at 55°C for 60 minutes, 9 grains of Macunium fluoride with a particle size of 0007 μm (manufactured by Sumitomo Cement Co., Ltd., trade name, Super i2!! Particulate Macunonium fluoride) The diameter is o.

Silicon oxide with a particle size of 2 μm (manufactured by Sumitomo Cement Co., Ltd., trade name, Ultrafine Particle Noriyoku), aluminum oxide with a particle size of 0.07 μm (manufactured by Sumitomo Cement Co., Ltd., trade name, Ultrafine Particle Alumina), or fine powders thereof, etc. A coating composition is prepared by adding 50% by weight of the solids content of each compound to the coating composition. Next, the coating composition was dispersed in a sand mill for one week, and it was confirmed that it had become a transparent coating. Then, coat a glass plate with a barcode, heat it at 150℃ for 30 minutes, and apply a 0.1μ
A film of m thickness was obtained.

The refractive index of the film was calculated by measuring the reflectance. The results are shown in Table 1.

(Margin below) Table 1 Coating film) Film strength □ □ - Filler 1 Refractive index (pencil strength) - Fluoride, 1.82; 8Hl) Magnesium 1: Silicon oxide 1 1.831 91-+.

:: Oxidation 1. 201.1 711 ・; Aluminum □ Equivalent compound ′ +, s3 8) 1.

: Additive-free 2.3] 1 9H As shown in Table 1, by adding macanium fluoride, silicon oxide, aluminum oxide, and a mixture thereof to a paint composition consisting of Chitanoe Kit, additive-free paint can be obtained. It is possible to change the refractive index without significantly lowering the film strength.

[Experimental Example 2] After mixing 23 parts by weight of tetraethquin titanium, 8 parts by weight of water, and 0.1 part by weight of hydrochloric acid as a titanium alcokit,
The same procedure as in Experimental Example 1 was carried out until the solid content of the paint crude material containing T107 of tetraethoquinotitanium reached 10.30.50.70% by weight when partially hydrolyzed by heating at °C for 60 minutes. Magnenium fluoride fine powder, silicon oxide powder, and aluminum oxide fine powder were added, each was dispersed in a sand mill for a week, and one coat of paint was applied to each glass plate using a bar code, and heated at 150℃ for 30 minutes to form a transparent coating film. Obtained. The refractive index was measured in the same manner as in Experimental Example 1. The results are not shown in Tables 2, 3, and 47.

(Margin below) Table 2 Table 3 (Weight%) □l 101 301 501 70 1
Table 4: Mixing ratio 1 Silicon oxide compound coating film/Electricity purchase %)l
](130:'50.' 70:Refractive index 12
．． 0941], 8951.7511+, 499 'As shown in Tables 2, 3, and 4'), fine magnesium fluoride powder, fine silicon oxide powder, and By changing the blending ratio of the aluminum oxide fine powder, the refractive index of the film can be changed continuously.

[Effects of the Invention] As explained above, the coating composition of the present invention comprises titanium alcokit, fine magnesium fluoride powder with a particle size of 0.1 μm or less, fine silicon oxide powder with a particle size of 0.1 μm or less, and Since the coating composition contains aluminum oxide fine powder with a diameter of 0.01 μm or less, the film formed on the substrate by the coating method is transparent without causing diffused reflection of light. In addition, since the above-mentioned fine powder having a refractive index lower than that of titanium oxide alone having a high refractive index is added alone or as a mixture, the film formed can be changed by changing the amount of the above-mentioned fine powder added. The refractive index can be changed continuously from 1.4 to 25.

First, the refractive index of the film formed can be changed by changing the type of the fine powder, or by changing the mixing ratio when the fine powders are mixed.

Therefore, the coating composition of the present invention has the advantage of being able to produce a coating that changes the refractive index of the film continuously, so that the antireflection multilayer film can be freely set without being limited to a specific refractive index. Not only can the design be made easier, but the number of films can be reduced to the point where the design becomes more reasonable, resulting in a reduction in the number of manufacturing steps and a reduction in costs.

In addition, even if the film is formed on substrates with different refractive indexes, by changing the amount of the fine powder blended, etc., the refractive index of the film and the substrate can be brought close to each other, thereby suppressing the occurrence of moiré patterns. It is possible.

Therefore, according to the coating composition of the present invention, a coating with a desired refractive index can be obtained, thereby preventing the occurrence of moiré patterns, and providing an excellent film strength that almost maintains the high strength of titanium oxide. A hard coat film can be formed on an optical substrate by a much simpler method than conventional vacuum film formation.

Claims (1)

[Claims] Contains at least one of titanium alkoxide and fine magnesium fluoride powder with a particle size of 0.1 μm or less, fine silicon oxide powder with a particle size of 0.1 μm or less, and fine aluminum oxide powder with a particle size of 0.1 μm or less. A coating composition comprising: at least one of the magnesium fluoride fine powder, silicon oxide fine powder, and aluminum oxide fine powder accounting for 3 to 90% by weight of the solid content in the coating composition; A coating composition comprising monodispersed fine powder.