JPH04264171A - Ultraviolet-absorbing film and film-forming composition - Google Patents

Abstract

PURPOSE:To provide a film-forming composition from which an ultraviolet- absorbing film can be formed on the surface of a transparent substrate such as glass and an ultraviolet-absorbing film. CONSTITUTION:An ultraviolet-absorbing film containing a titanium alkoxide or its hydrolyzate or condensate, acetylacetonatozinc or its hydrolyzate or condensate, and an inorganic zinc compound, and an ultraviolet-absorbing film- forming composition comprising a titanium alkoxide or its hydrolyzate or condensate, acetylacetonatozinc or its hydrolyzate or condensate, an inorganic zinc compound, water and a hydrophilic solvent.

Description

[Detailed description of the invention]

0001

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

0002

[Prior Art] Methods for efficiently absorbing ultraviolet rays into transparent substrates such as glass include methods of including an ultraviolet absorbing substance in the glass composition in advance, and methods of applying a paint containing an ultraviolet absorbing substance to the glass surface. etc. are being carried out. However, in the method of incorporating an ultraviolet absorbing substance into glass, CeO2, FeO, TiO2, etc. are added to the glass composition in advance, so it is not possible to easily impart an ultraviolet absorbing effect to ready-made glass products.

[0003] Paints containing ultraviolet absorbing substances include:
There are organic paints and inorganic paints. As an organic paint,
2,2'-dihydroxy-4-mesoxybenzophenone, 2,2'-
Organic UV absorbers such as dihydroxy-4,4'-dimezooxybenzophenone and ethyl-2-cyano-3-phenyl-cinnamate, and inorganic UV absorbers such as titanium oxide, iron oxide, and zinc oxide. Fine particles are added and applied to the glass surface, but with organic UV absorbers, if used for a long time or in a high temperature atmosphere, the UV absorber may decompose or form on the coating surface. There are problems such as bleeding and discoloration of the coating film.Furthermore, fine particles of inorganic ultraviolet absorbing substances have the disadvantage that they are difficult to disperse in the resin and also cut visible light. Furthermore, organic paints have the disadvantage that the resin in the paint itself does not have good UV resistance, resulting in deterioration, peeling, and discoloration of the paint film after long-term use. Some inorganic paints are made by dispersing ultraviolet absorbers in water glass or the like, but they have the problem of high baking temperatures and restrictions on substrates and coating conditions.

In contrast, recently, ultraviolet absorbing films have been produced using the sol-gel method. This process converts transition metal alkoxides such as tetraalkyl titanates into water, alcohols, etc.
The method aims to obtain an ultraviolet absorbing film by dissolving the solution in a mixed solvent such as silica to form a homogeneous solution, coating it on a substrate such as glass by a method such as dipping, and then heat-treating it at a relatively low temperature. be. This method allows the inorganic ultraviolet absorbing thin film to be coated uniformly at a relatively low temperature, but
Metal alkoxides such as tetraalkyl titanate are highly reactive and have the disadvantage of poor storage stability, such as gelation of coating liquids and precipitation of reactants over time.

[0005]

Problems to be Solved by the Invention The present inventors have conducted various studies with the aim of producing a paint that can be applied to ready-made transparent substrates and efficiently blocks ultraviolet rays. As a result, we found that a mixed solution of titanium tetraalkoxide and zinc acetylacetonate in water and alcohol is stable at room temperature for a long period of time, and that the coating film absorbs ultraviolet rays well and transmits visible light. It was discovered that by coexisting with a relatively low hydrolyzable zinc inorganic compound, zinc inorganic fine particles are precipitated when forming a coating film, thereby further blocking ultraviolet rays, and this led to the completion of the present invention. .

[0006]

[Means for solving the problems] That is, the present invention has the following features:
It is an ultraviolet absorbing film containing (A) titanium alkoxide, its hydrolysis or condensate, (B) zinc acetylacetonate, its hydrolysis or condensate, (C) a zinc inorganic compound, and further comprises (A) titanium Alkoxide, hydrolysis or condensate thereof, (B) Zinc acetylacetonate hydrolysis or condensate thereof, (C) Zinc inorganic compound, (D)
This is an ultraviolet absorbing film forming composition containing water and (E) a hydrophilic solvent. Further, the present invention is an ultraviolet absorbing film or film-forming composition in which the zinc inorganic compound is one or more selected from zinc chloride, zinc carbonate, zinc sulfate, and zinc acetate.

[0007] The titanium alkoxide in the present invention is:
Examples include titanium tetramethoxide, titanium tetraethoxide, titanium tetraisopropoxide, titanium tetrabutoxide, and the like. What are its hydrolysis and condensate products?
The titanium alkoxide and water react to form an oligomer.
It is a colloidal substance. the titanium alkoxide and/or hydrolysis of the titanium alkoxide;
Condensates (hereinafter abbreviated as titanium alkoxides) are easily dissolved or dispersed in hydrophilic solvents such as alcohol.

A solution or dispersion of a hydrophilic solvent of titanium alkoxides becomes a transparent and uniform solution by heating it together with zinc acetylacetonate and water. This solution is applied to a transparent substrate such as a glass plate by a dipping method or the like to form a transparent film. This coating film itself blocks ultraviolet rays to a large extent, but by dissolving zinc inorganic compounds such as zinc chloride, zinc carbonate, zinc sulfate, and zinc acetate in this coating liquid, ultraviolet rays can be further blocked. At this time, these zinc inorganic compounds are difficult to hydrolyze, and in order to block ultraviolet rays, it is desirable that they be precipitated in the coating film as ultrafine particles during application and drying of the coating solution. In addition, the precipitated particle size was 10
If it exceeds 0 nm, it is not desirable because it cuts not only ultraviolet rays but also some visible light.

The hydrophilic solvent used 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, butyl cellosolve, formamide, N,N-dimethylformamide, N,N-dimethylacetamide, N, - Amides such as methylpyrrolidone, nitriles such as acetonitrile and butyronitrile, and the like.

[0010] In the above coating liquid, the molar ratio of titanium alkoxides and zinc acetylacetonate is arbitrary, but it is more preferable that the ratio of Zn/Ti is about 1/3 to 3/1. When it is less than 1/3, the condensation of titanium alkoxides progresses, and titanium oxide particles tend to precipitate and precipitate.
In practical terms, there is a problem with storage stability. If it exceeds 3/1, the solubility will deteriorate and zinc acetylacetonate will precipitate from the system, which is not preferred in practice. The solid content of the coating liquid is not particularly limited, but it is between 2% and 50% by weight, including metal oxides.
% is preferable. If it is less than 2%, the film thickness of the coating film cannot be increased, and if it exceeds 50%, the gelation time of the system will be shortened and it will not withstand storage. The amount of water added is not particularly limited, but it is more preferably about 0.1 to 20% by weight of the coating liquid. 0.1%
If it is less than 20%, the hydrolysis of titanium alkoxide and zinc acetylacetonate will not progress and the coating film will easily whiten, and if it exceeds 20%, gelation of the system will be promoted and it will not be usable. Although the amount of the zinc inorganic compound added is arbitrary, it 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 UV blocking effect will be low, and if it exceeds 50%, the visible light transmittance will be low.

The ultraviolet blocking paint thus obtained can be applied to transparent substrates such as glass and plastics, or substrates that are not durable against ultraviolet rays, by methods such as dip coating, spray coating, and brush coating. will be constructed. The coated base material is
By drying at room temperature or by heating, a film in which ultrafine zinc inorganic compound particles are uniformly dispersed in an amorphous titanium/zinc composite oxide film is formed. Considering the durability of the coating film, it is desirable to dry at 80° C. or higher. If the film thickness is insufficient with one coat, you may apply several coats.

The resulting coating film is an amorphous inorganic coating film that has excellent durability and blocks UV rays well, but if the base material is made of a heat-resistant material, it can be heated to 400 to 500°C. A crystalline coating film may be obtained by doing so. This sintered coating has strong surface hardness and also blocks UV rays. The coating liquid according to the present invention may contain an organic resin, a viscosity modifier, etc., as necessary, as long as the effects of the present invention are not impaired. Next, Examples and Comparative Examples will be given to specifically explain the present invention. Hereinafter, "parts" refer to "parts by weight" unless otherwise specified.

Example 1 10 parts of tetraisopropyl titanate was added to a mixed solution of 100 parts of isopropyl alcohol and 2 parts of purified water at room temperature to form a homogeneous solution. To this, zinc acetylacetonate 10
Parts by weight and 2 parts of zinc chloride were added and heated to 80°C to dissolve. The dissolved and homogeneous coating liquid remained stable 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 film thickness was 0.3 μm. This one is 450n
Although 85% or more of visible light of 350 nm was transmitted, the transmittance of ultraviolet rays of 350 nm was less than 10%.

Example 2 To a mixed solution of 100 parts of butyl cellosolve and 2 parts of purified water, 10 parts of tetraisopropyl titanate was added at room temperature to form 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 them. The dissolved and homogeneous coating liquid remained stable 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 film thickness was 0.3 μm. This material transmitted 85% or more of visible light of 450 nm, but the transmittance of ultraviolet light of 350 nm was less than 10%.

Comparative Example 1 5 parts of tetraisopropyl titanate was added to a mixture of 100 parts of isopropyl alcohol and 2 parts of purified water at room temperature.
℃ for one week, a titanium oxide precipitate was deposited. Comparative Example 2 10 parts of tetraisopropyl titanate was added to 100 parts of isopropyl alcohol at room temperature to form a homogeneous solution. To this, 10 parts by weight of zinc acetylacetonate and 2 parts of zinc chloride were added and heated to 80°C to dissolve them. When this coating liquid was applied to a glass plate by a dipping method and dried at 100°C for 30 minutes, the coating film turned white. Comparative Example 3 10 parts of tetraisopropyl titanate was added to a mixed solution of 100 parts of isopropyl alcohol and 2 parts of purified water at room temperature to form a homogeneous solution. To this, zinc acetylacetonate 10
Parts by weight were added and heated to 80°C to dissolve. The dissolved and homogeneous coating liquid remained stable 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. Film thickness is 0.
It was 3 μm. This thing has a visible light wavelength of 450 nm, which is 8
Transmits more than 5%, and the transmittance of 350nm ultraviolet rays is 40%.
Met.

Claims (3)

[Claims] [Claim 1] Ultraviolet absorption characterized by containing (A) titanium alkoxide, its hydrolysis or condensate, (B) zinc acetylacetonate, its hydrolysis or condensate, and (C) a zinc inorganic compound. film. Claim 2: (A) titanium alkoxide, its hydrolysis or condensate, (B) zinc acetylacetonate, its hydrolysis or condensate, (C) zinc inorganic compound, (D)
An ultraviolet absorbing film-forming composition comprising water and (E) a hydrophilic solvent. 3. The ultraviolet absorbing film-forming composition according to claim 1, wherein the zinc inorganic compound is one or more compounds selected from zinc chloride, zinc carbonate, zinc sulfate, and zinc acetate.