JP2827542B2 - Ultraviolet absorbing film forming composition and use thereof - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film-forming composition for forming an ultraviolet absorbing film on the surface of a transparent substrate such as glass, and an ultraviolet shielding material using the same.

[0002]

2. Description of the Related Art As a method of efficiently absorbing ultraviolet rays to a transparent substrate such as glass, a method of including an ultraviolet absorbing substance in a glass composition in advance, and a method of applying a paint containing an ultraviolet absorbing substance to a glass surface or the like are known. And so on. However, since a method of incorporating an ultraviolet absorbing substance into glass is such that CeO ₂ , FeO, TiO _{2 and the} like are added in advance to a glass composition, it is not possible to easily impart an ultraviolet absorbing effect to a ready-made glass product or the like. Can not.

[0003] As a paint to which an ultraviolet absorbing material is added,
There are organic paints and inorganic paints. As organic paints,
2,2'-dihydroxy-4-mesooxybenzophenone, 2,2'-
Organic ultraviolet absorbers such as dihydroxy-4,4'-dimesoxybenzophenone and ethyl-2-cyano-3-phenyl-cinnamate; and inorganic ultraviolet absorbers such as titanium oxide, iron oxide and zinc oxide. Fine particles etc. are added and applied to the glass surface.However, those using organic UV absorbers may be decomposed by long-term use or use in a high temperature atmosphere. There are problems such as bleeding and discoloration of the coating film. Further, the inorganic ultraviolet absorbing fine particles are difficult to disperse in the resin, and have the drawback of cutting off visible light. Furthermore, organic paints have the disadvantage that the resin itself in the paint has poor UV resistance, so that the coating film deteriorates, peels off, discolors, etc. due to long-term use. Some inorganic paints have an ultraviolet absorber dispersed in water glass or the like, but have a problem that the baking temperature is high and the base material and coating conditions are limited.

On the other hand, recently, an ultraviolet absorbing film has been produced by a sol-gel method. This is accomplished by converting a transition metal alkoxide such as a tetraalkyl titanate into water, an alcohol-
To obtain a UV-absorbing coating by dissolving it in a mixed solvent such as water, making it a uniform solution, coating it on a substrate such as glass by dipping or the like, and then heat-treating it at a relatively low temperature. is there. In this method, the inorganic ultraviolet absorbing thin film can be coated uniformly at a relatively low temperature,
Metal alkoxides such as tetraalkyl titanates have high reactivity, and have the drawback of poor storage stability such as gelling of the coating solution over time and sedimentation of reactants.

[0005]

DISCLOSURE OF THE INVENTION The present inventors have made various studies for the purpose of producing a coating material which can be applied to a ready-made transparent substrate and which cuts ultraviolet rays efficiently. As a result, a mixed solution of titanium tetraalkoxide and zinc acetylacetonate in water or alcohol is stable at room temperature for a long period of time, and the coating film absorbs ultraviolet light well and transmits visible light. By coexisting a zinc compound having a relatively low hydrolyzability, the present inventors found that zinc compound fine particles were precipitated when forming a coating film and that ultraviolet rays were further cut off, thereby completing the present invention.

[0006]

[Means for Solving the Problems] That is, the present invention provides:
An ultraviolet absorbing film-forming composition comprising (A) titanium alkoxide, (B) zinc acetylacetonate, (C) zinc compound, (D) water, and (E) a hydrophilic solvent. The present invention also provides the composition for forming an ultraviolet absorbing film, wherein the zinc compound is one or more selected from zinc chloride, zinc carbonate, zinc sulfate, and zinc acetate. Further, the present invention is an ultraviolet ray blocking material obtained by applying the above-mentioned composition for forming an ultraviolet ray absorbing film to a substrate and then drying it.

[0007] The titanium alkoxide in the present invention is:
For example, titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, titanium tetrabutoxide and the like can be mentioned. Titanium alkoxide reacts with water and hydrolyzes to form a colloidal condensate. Titanium alkoxides and hydrolysis and condensation products of titanium alkoxides (hereinafter abbreviated as titanium alkoxides)
Is easily dissolved or dispersed in a hydrophilic solvent such as alcohol.

A solution or dispersion of a hydrophilic solvent of titanium alkoxides becomes a transparent and uniform solution by heating with zinc acetylacetonate and water. The solution is applied to a transparent substrate such as a glass plate by dipping or the like to form a film, thereby forming a transparent film. Although the coating film itself blocks ultraviolet rays considerably, the ultraviolet rays can be further blocked by dissolving a zinc compound such as zinc chloride, zinc carbonate, zinc sulfate or zinc acetate in the coating solution. At this time, these zinc compounds are hardly hydrolyzed, and it is desirable to precipitate as ultra-fine particles in the coating film during application and drying of the coating solution in order to cut off ultraviolet rays. On the other hand, if the precipitated particle diameter exceeds 100 nm, not only ultraviolet light but also visible light is partially cut off, which is not desirable.

The hydrophilic solvent in the present invention is not particularly limited as long as it can be arbitrarily dissolved in water. Examples include alcohols such as methanol, ethanol and isopropanol, ketones such as acetone, cellosolves such as methyl cellosolve, ethyl cellosolve and butyl cellosolve, formamide, N, N-dimethylformamide, N, N-dimethylacetamide, N Amides such as methylpyrrolidone; nitriles such as acetonitrile and butyronitrile;

In the above coating solution, the molar ratio of titanium alkoxide to zinc acetylacetonate is arbitrary, but more preferably Zn / Ti is about 1/3 to 3/1. If it is 1/3 or less, the condensation between titanium alkoxides proceeds further, and particles of titanium oxide are easily precipitated and precipitated,
There is a problem in storage stability in practical use. If it exceeds 3/1, the solubility becomes poor and zinc acetylacetonate precipitates from the system, which is not practically preferable. The solid content of the coating liquid is not particularly limited, but is 2% to 50% by weight based on the weight of the metal oxide.
% Is preferable. If it is less than 2%, the film thickness of the coating film is indispensable. The amount of water to be added is not particularly limited, but is preferably about 0.1 to 20% by weight of the coating liquid. 0.1
% Or less, the hydrolysis of titanium alkoxide or zinc acetylacetonate does not proceed, and the coating film is liable to whiten. If it exceeds 20%, the gelation of the system is promoted and the product cannot be used. The addition amount of the zinc inorganic compound is optional, but is more preferably about 5 to 50% by weight based on the solid content of the coating liquid. If it is less than 5%, the effect of blocking ultraviolet rays is small, and if it exceeds 50%, the visible light transmittance is reduced.

The composition for forming an ultraviolet absorbing film thus obtained is applied to a transparent substrate such as glass or plastic, or a substrate having no durability against ultraviolet rays, such as dip coating, spray coating, brush coating, or the like. Coated by the method. The coated substrate is dried at room temperature or by heating to form a film in which ultrafine zinc compound particles are uniformly dispersed in an amorphous titanium / zinc composite oxide film. In consideration of the durability of the coating film, drying at 80 ° C. or more is desirable. 1
When the film thickness is not enough after the first coating, the coating may be repeated several times.

The resulting coating film is an amorphous inorganic coating film which has excellent durability and blocks ultraviolet rays well, but if the substrate is made of a heat-resistant material, it is heated to 400 to 500 ° C. Then, a crystalline coating film may be formed. The sintered coating has a strong surface hardness and simultaneously blocks ultraviolet light. The coating liquid according to the present invention may be added with an organic resin, a viscosity modifier and the like as needed as long as the effects of the present invention are not impaired. Next, Examples and Comparative Examples will be given in order to specifically explain the present invention. Hereinafter, “parts” indicates “parts by weight” unless otherwise specified.

Example 1 To a mixture of 100 parts of isopropyl alcohol and 2 parts of purified water, 10 parts of tetraisopropyl titanate was added at room temperature to obtain a uniform solution. In addition, zinc acetylacetonate 10
Parts by weight and 2 parts of zinc chloride were added and heated to 80 ° C. to dissolve. The coating liquid which was dissolved and became uniform maintained the coating liquid stably even after 3 months at 50 ° C. The obtained coating liquid was applied to a glass plate by a dipping method, and dried at 100 ° C. for 30 minutes. The thickness was 0.3 μm. This is 450n
The visible light of m was transmitted by 85% or more, but the transmittance of ultraviolet light of 350 nm was less than 10%.

EXAMPLE 2 Tetraisopropyl titanate (10 parts) was added to a mixture of butyl cellosolve (100 parts) and purified water (2 parts) at room temperature to obtain a homogeneous solution. To this, 10 parts by weight of zinc acetylacetonate and 2 parts of zinc acetate were added and heated to 80 ° C. to dissolve.
The coating liquid which was dissolved and became uniform maintained the coating liquid stably even after 3 months at 50 ° C. The obtained coating liquid was applied to a glass plate by a dipping method, and dried at 100 ° C. for 30 minutes. The thickness was 0.3 μm. This material transmitted at least 85% of visible light of 450 nm, but had a transmittance of ultraviolet light of 350 nm of less than 10%.

Comparative Example 1 To a mixture of 100 parts of isopropyl alcohol and 2 parts of purified water, 5 parts of tetraisopropyl titanate was added at room temperature.
When left at ℃ for 1 week, a precipitate of titanium oxide was deposited. Comparative Example 2 Tetraisopropyl titanate (10 parts) was added to isopropyl alcohol (100 parts) at room temperature to obtain a uniform solution. 10 parts by weight of zinc acetylacetonate and 2 parts of zinc chloride
And heated to 80 ° C. to dissolve. This coating solution was applied to a glass plate by a dipping method, and dried at 100 ° C. for 30 minutes. As a result, the coating film turned white. Comparative Example 3 Tetraisopropyl titanate (10 parts) was added to a mixture of isopropyl alcohol (100 parts) and purified water (2 parts) at room temperature to obtain a uniform solution. In addition, zinc acetylacetonate 10
Parts by weight were added and heated to 80 ° C. to dissolve. The coating liquid which was dissolved and became uniform maintained the coating liquid stably even after 3 months at 50 ° C. The obtained coating liquid was applied to a glass plate by a dipping method, and dried at 100 ° C. for 30 minutes. The thickness was 0.3 μm. It transmits at least 85% of 450 nm visible light and has a transmittance of 350 nm ultraviolet light of 4%.
It was 0%.

Claims (3)

(57) [Claims] 1. A titanium alkoxide , (B) zinc acetylacetonate , (C) a zinc compound, (D) water,
(E) An ultraviolet absorbing film comprising a hydrophilic solvent
Forming composition . 2. The method according to claim 1, wherein the zinc compound is zinc chloride, zinc carbonate, sulfuric acid.
One or more selected from zinc and zinc acetate
The ultraviolet absorbing film forming composition according to claim 1, which is a compound . 3. The ultraviolet absorbent according to claim 1 or 2, wherein
It is characterized by drying after coating the film-forming composition.
Ultra-violet ray blocking material.