JPS6241465B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a laminate in which at least one side of a metal thin film layer is covered with a transparent high refractive index dielectric layer, and more specifically, the present invention relates to a laminate comprising a transparent high refractive index dielectric layer formed chemically from an organic titanium compound. Regarding improvements. In general, in a laminate in which conductive metal thin films such as gold, silver, copper, palladium, and certain alloys thereof are sandwiched between transparent high refractive index dielectric layers, the thickness of each constituent thin film is controlled. It is known that this allows selective reflection of light in a specific wavelength range. In particular, a laminate that selectively reflects infrared wavelength regions is important as a heat ray reflective film from the viewpoint of energy saving in houses and the like and utilization of solar energy. Such a laminate includes Bi ₂ O ₃ /Au/
Laminated bodies such as Bi ₂ O ₃ , ZnS/Ag/ZnS and TiO ₂ /Ag/TiO ₂ have been proposed, and the formation of these films is
The methods used were vacuum evaporation, reactive evaporation, and sputtering. However, although physical methods such as vacuum evaporation and sputtering are effective in forming metal thin films, they have problems in industrial productivity and adhesion to organic substrates in forming metal oxide thin films. There are many cases. As a solution to this problem, the present inventors have already proposed a method in which a transparent high refractive index dielectric layer is formed from an organometallic compound by chemical means. That is, to give a typical example, a titanium oxide thin film layer with a high refractive index can be formed by applying an organic solvent solution of alkyl titanate onto a substrate and treating it at a relatively low temperature, and this can be combined with a vapor-deposited metal thin film layer. By combining, infrared reflectance is over 95%, visible light (500mμ)
It has become possible to economically produce a TiO ₂ /Ag/TiO ₂ three-layer laminate with a transmittance of 75% or more. Moreover, since the processing temperature is low, it is also possible to use an organic polymer substrate such as polyethylene terephthalate as a substrate, and by continuously forming a laminate on the film, a laminate with extremely excellent performance economically. It became possible to obtain a body. Although the above method is an extremely excellent method, the formed titanium oxide layer has some structural defects, and therefore, the titanium oxide layer formed by physical means such as sputtering is Depending on the conditions of use, the durability may be inferior to that of the case where it is used. In order to improve this drawback, the present inventors have conducted extensive research and found that monovalent alkali metals or
The present invention was achieved by discovering that the inclusion of valent alkali metal ions is extremely effective. That is, the present invention provides (1) a laminate consisting of a molded substrate and a metal thin film layer (A) whose one or both sides are covered with a transparent thin film layer (B), in which the transparent high refractive index thin film layer ( A laminate characterized in that at least one of B) is composed of a titanium oxide thin film layer (B-1) formed from an organic titanate compound and contains a monovalent alkali metal and/or a monovalent alkali metal ion. , (2) The titanium oxide thin film layer (B-1) is titanium 1
The laminate described in item 1 above containing 0.005 to 0.2 alkali metal atoms per atom (including those in an ionic state), and (3) the alkali metal and/or alkali metal contained in the titanium oxide thin film layer. The ion is Li,
The laminate according to item 1 or 2 above, which is one or more metals or metal ions selected from the group consisting of Na, K, and Rb. The transparent molded substrate (A) referred to in the present invention may be a transparent molded product of an organic polymer material, a molded product of an inorganic material such as glass or metal oxide, or a composite of both. However, from the viewpoint of industrial productivity, organic polymer materials are preferred, and film-like materials are particularly preferred. In particular, polyethylene terephthalate film, nylon film, polycarbonate film, polyethylene film, etc. are practically preferred. The material of the metal thin film layer (C) used in the laminate of the present invention may be any metal or alloy with low absorption loss in the visible light region, such as gold, silver, copper, aluminum, nickel, palladium, Tin or an alloy thereof is preferably used.
In particular, silver, copper, palladium, or an alloy thereof is preferable in order to obtain a transparent conductive film with high transmittance, and gold, silver, copper, or an alloy thereof is preferable in order to obtain a selective light transmitting film with high infrared reflection ability. Alloys are preferred. The thickness of the metal thin film is not particularly limited as long as it has the required characteristics as a transparent conductive film or selective light transmission film, but in order to have infrared light reflective ability or conductivity, it must have at least a certain degree of thickness. It is necessary to have continuity in the area. It is preferable that the film thickness be about 50 Å or more, which is more suitable for a continuous structure than an island structure, and that it should be reduced to 600 Å from the viewpoint of transparency to solar energy. The thinner the metal thin film layer is, the wider the light transmission area becomes.
In order to increase transparency, a film thickness of 170 Å or less is recommended.
In order to have sufficient conductivity or infrared light reflecting ability, a film thickness of 100 Å or more is preferable. The metal thin film layer (C) can be formed by, for example, a vacuum evaporation method, a cathode sputtering method, a plasma spraying method, a vapor phase plating method, a chemical plating method, or a combination thereof. In a laminate using a substrate, if the surface of the substrate such as a sheet or film is smooth, from the viewpoint of uniformity of the formed thin film, ease of production, and film formation speed,
A cathode sputtering method is suitable. In particular, when forming an alloy thin film, the cathode sputtering method is most suitable. One of the transparent high refractive index dielectric thin film layers (B) and (D) referred to in the present invention does not necessarily need to contain the alkali metal or alkali metal ion defined in the present invention. In that case, such a transparent high refractive index dielectric layer that does not contain alkali metals or alkali metal ions is defined as a dielectric layer with a refractive index of 1.6 or more for visible light;
It preferably has a refractive index of 1.8 or more and a visible light transmittance of 80% or more, preferably 90% or more,
The film thickness is 50 to 600 Å, preferably 120 to 400 Å. Examples of such materials include titanium oxide, bismuth oxide, zinc sulfide, tin oxide, indium oxide, and the like. Methods for forming these thin film layers include physical methods such as sputtering and vacuum deposition, and chemical methods such as coating with an organic metal compound solution. The improved transparent high refractive index dielectric layer of the present invention comprises (a) at least one compound selected from the group consisting of tetraalkyl titanates and condensates thereof, and (b ₁ ) water such as KOH, NaOH, LiOH, RbOH, etc. Alkali oxide compound (b ₂ ) Alkali metals such as sodium metal, potassium metal, etc. (b ₃ ) Generated from a reaction product with an alkali metal oxide such as Na ₂ O, K ₂ O, etc. In this case, the alkali used may be one type or a mixture of several types. The alkyl group of the organic titanate used in the present invention is not particularly limited, and includes ethyl, propyl,
Examples include isopropyl, butyl, 2-ethylhexyl, stearyl and the like, among which propyl and butyl are preferably used. These condensates are obtained by condensing two or more tetraalkyl titanates. For example, the expression [However, in the formula, R represents an alkyl group, and m is a positive integer. ] It is a compound represented by the following or a mixture thereof, and from the viewpoint of ease of handling, m is preferably 10 or less. In particular, dimers, tetramers, decamers, etc. of tetra-n-butyl titanate and tetrapropyl titanate are preferably used from the viewpoint of coatability. Further, these condensates may be obtained by any method. Further, the alkali hydroxide compound used in the present invention is preferably a monovalent alkali hydroxide such as KOH, NaOH, LiOH, or RbOH. Titanium oxide thin film layer (B-1) containing an alkali metal or alkali metal ion in the present invention
To produce the alkali hydroxide compound, the organic titanate may be reacted with the organic titanate, and then the organic titanate may be diluted with a suitable solvent, and the resulting solution may be applied onto a substrate and dried. In this case, the solvent should meet the following conditions: solubility for the solute, evaporability (preferably boiling point below 150℃), inertness (does not react with the solute and deactivate the three-dimensional reticulation reaction), etc. good. Particularly preferred are hydrocarbons such as n-heptane and cyclohexane, general-purpose solvents such as ethyl alcohol, isopropyl alcohol, and n-butanol, and mixed solvents thereof. In the present invention, water plays an effective role in promoting three-dimensional network formation of the coating film, but the water may be moisture in the air, or a small amount of water may be coexisting in the coating solution in advance. Good too. In addition, in order to obtain stability of the coating solution, acetylacetone, acetoacetate, diacetone alcohol, lactic acid, glycolic acid, etc., are added to the above solution.
It is also effective to add a known chelating agent such as an oxyacid. Particularly when the alcoholic solvent contains a small amount of water, the addition of the chelating agent is particularly effective in suppressing hydrolysis of the coating solution and improving coating properties and storage stability. Although known alkyl silicate curing catalysts such as sodium acetate, potassium acetate, and cobalt naphthenate are effective as catalysts for accelerating the curing of the coating film, such catalysts are not necessarily required under normal coating conditions. This is considered to be because the alkyl titanate itself acts as a transesterification reaction catalyst. Methods for reacting alkali hydroxide and organic titanate include a method of directly reacting a predetermined amount of organic titanate with alkali hydroxide, or a method of reacting organic titanate diluted with a solvent and alkali hydroxide. The solvent in this case is preferably a solvent that can dissolve the alkali hydroxide, such as alcohol. By reacting an alkali hydroxide with an organic titanate, the organic titanate becomes a highly concentrated compound, and the terminal -OH group formed by partial hydrolysis becomes -
It is thought that it changes to an OM group (M is one of Li, Na, K, and Rb). From these points, organic titanate reacted with alkali hydroxide becomes highly three-dimensional when coated, forming a more uniform high refractive index dielectric layer, and stabilizing the metal thin film layer formed in contact with it. It is thought that the effect appears. If the amount of alkali hydroxide that reacts with the organic titanate is too small or too large, it will become highly three-dimensional, making it difficult to form a more uniform high refractive index dielectric layer, and the layer will be difficult to form. Since the stabilizing effect on the metal thin film layer formed in contact with it disappears, there is naturally an optimum range for the amount of reaction. In order to obtain a laminate with excellent durability, which is the object of the present invention, the molar ratio of alkali metal per titanium atom in the formed titanium oxide thin film layer is expressed as M.
It is preferable that 0.005≦M/Ti≦0.2. If the molar ratio is less than 0.005, no effect will be observed, and if the molar ratio exceeds 0.2, the adhesiveness and light transmittance of the transparent high refractive index thin film layer will decrease, which is not preferable. In addition, the contained state is -OM group (M is Li, Na, K, Rb
The alkali metal may be present as a free ion, but if it is desired to have a stabilizing effect on the metal thin film layer formed in contact with the alkali metal, the alkali metal contained in the - OM group (M is Li,
There must be a majority of the type (one of Na, K, Rb). Further, in the laminate of the present invention, a transparent protective layer may be formed on the transparent high refractive index thin film layer (B-1) formed on the metal layer for the purpose of protecting the laminate structure. Such a transparent protective layer may be made of any material as long as it does not impair the desired optical properties of the laminate and improves environmental stain resistance and surface hardness, but in particular, inorganic compounds may be used. In the case of , oxides such as SiO ₂ , TiO ₂ and Al ₂ O ₃ are preferable, and in the case of organic compounds, acrylic resins such as polymethacrylonitrile, polymethylmethacrylate, and polyacrylonitrile are preferably used. . It is also possible to laminate a stretched polypropylene film or the like. The thickness of the protective layer may be any thickness that provides the desired protective effect of the protective layer, and is preferably from 0.05 μm to 30 μm. Next, a method for analyzing alkali metals or alkali metal ions contained in the transparent high refractive index thin film layer formed by the method of the present invention will be described. The transparent high refractive index thin film layer formed on the substrate is cut out from a constant area of about 5 mm square to create a thin piece. Place the resulting strips in a test tube, add a small amount of water, and extract with an ultrasonic cleaner for about 60 minutes. Remove only water from the test tube and add a certain amount of washing water to thoroughly rinse the pieces. The rinsing water is added to the ultrasonic extraction solution. This solution is called solution (A). Furthermore, add a certain amount of 0.1N hydrochloric acid aqueous solution to the strip in the test tube and extract for 60 minutes using an ultrasonic cleaner. Take out the obtained extract, rinse the test tube thoroughly, and add this solution to the extract, which is referred to as solution (B). Titrate solution (A) with hydrochloric acid using phenolphthalein as an indicator and a PH meter. After the titration is completed, the amount is determined by atomic absorption spectrometry and combined with the value from the titration. The quantitative value obtained from the solution (A) corresponds to the amount of free alkali contained in the transparent high refractive index thin film layer. Similarly, quantify the amount of alkali extracted into solution (B) using atomic absorption spectrometry. The quantitative value obtained from solution (B) corresponds to the amount of alkali reacted with the organic titanate. The sum of the two quantitative values is the total amount of alkali metal or alkali metal ion contained in the transparent high refractive index thin film layer in the present invention. Hereinafter, a specific explanation of the present invention will be shown in Examples. Example 1 A biaxially stretched polyethylene terephthalate film with a light transmittance of 86% and a thickness of 75 μm was coated with a titanium oxide thin film layer with a thickness of 300 Å as the first layer, and a titanium oxide thin film layer with a thickness of 300 Å as the second layer.
140 Å thin film layer of silver and copper (90 wt% silver, 10 wt% copper) and 300 Å thick as third layer
Titanium oxide thin film layers were sequentially laminated to form a laminate having transparent conductivity and selective light transmittance on the film. All titanium oxide thin film layers were obtained by coating a reaction product of tetrabutyl titanate and potassium hydroxide as shown below. That is, 100g of tetrabutyl titanate and 30g of potassium hydroxide were heated in a dry _N2 atmosphere at 70°C while stirring well.
After reacting at ℃ for 2 hours, the tetrabutyl titanate was separated. A solution consisting of 3 parts of the obtained modified tetrabutyl titanate, 50 parts of n-hexane, and 47 parts of n-butanol was coated with a bar coater and heated to 120° C. for 5 minutes. The thin film layer consisting of silver and copper is a silver-copper alloy (silver
90% by weight and 10% by weight of copper) using a low-temperature magnetron sputtering method. The amount of K (potassium) contained in the first and third titanium oxide thin film layers was determined to be 0.006 per Ti by atomic absorption spectrometry. The obtained film had a light transmittance of 71%, a surface resistance of 10Ω/square, and an infrared reflectance of 92%. The resulting film was placed in a gear oven tester kept at 90°C and the infrared reflectance was measured after 2000 hours, and the infrared reflectance remained at 80% or higher. Comparative Example 1 The first and third titanium oxide thin film layers were made of 3 parts of unmodified tetrabutyl titanate and n-hexane.
A laminated film was prepared in the same manner as in Example 1 except that it was formed from a solution consisting of 50 parts of n-butanol and 47 parts of n-butanol. The obtained film had a light transmittance of 72%, a surface resistance of 12Ω/square, and an infrared reflectance of 92%. As a result of conducting a thermal deterioration acceleration test in the same manner as in Example 1, the infrared light reflectance decreased to 80% or less after about 1000 hours. Comparative Example 2 On the polyethylene terephthalate film used in Example 1, the first layer was a titanium oxide thin film layer with a thickness of 200 Å, and the second layer was a thin film layer of silver and copper with a thickness of 150 Å (90% silver, 10% copper). % by weight) and a titanium oxide thin film layer with a thickness of 200 Å as the third layer were sequentially laminated to form a laminate having transparent conductivity and selective light transmittance on the film. All titanium oxide thin film layers were obtained by coating a reaction product of tetrabutyl titanate and potassium hydroxide. 30 g of tetrabutyl titanate and 30 g of sodium hydroxide were mixed in a mixed solvent consisting of 1 part of n-butanol and 1 part of isopropanol, and the mixture was refluxed at 70°C for 1 hour. After the reaction was left at room temperature for 10 hours, the remaining alkali was removed, diluted with ligroin to prepare a solution containing 3% by weight of tetrabutyl titanate, and coated to obtain a titanium oxide thin film layer. The surface of the obtained laminate was slightly cloudy, the light transmittance was 47%, and the infrared light reflectance was 90%. The Na/Ti molar ratio in the obtained laminate was 0.375, indicating a high Na content. Example 2 On the polyethylene terephthalate film used in Example 1, the first layer was a titanium oxide thin film layer with a thickness of 270 Å, and the second layer was a thin film layer of silver and copper with a thickness of 170 Å (90% silver, 10% copper). % by weight) and a titanium oxide thin film layer with a thickness of 300 Å as the third layer were sequentially laminated to form a laminate having transparent conductivity and selective light transmittance on the film. All titanium oxide thin film layers were obtained by coating a reaction product of tetrabutyl titanate and potassium hydroxide as shown below. That is, 50 g of tetrabutyl titanate and 10 g of potassium hydroxide were stirred and mixed in n-butanol, and the mixture was kept at 50 DEG C. and refluxed for 1 hour. After the reaction, the mixture was left at room temperature for 24 hours and then separated, diluted with n-hexane to prepare a solution containing 5% by weight of modified tetrabutyl titanate, and coated to obtain a titanium oxide thin film layer. The resulting laminate had a light transmittance of 73% and an infrared reflectance of 95%. A 2 μm thick transparent protective layer made of polymethacrylonitrile was further formed on the obtained laminate to protect the surface. The transparent protective layer is 10 parts of polymethacrylonitrile,
A solution consisting of 40 parts of cyclohexanone and 50 parts of methyl ethyl ketone was applied using a bar coater and dried at 130° C. for 5 minutes using a hot air dryer. The obtained laminate was tested by the heat resistance accelerated aging method used in Example 1, and the infrared light reflectance remained at 85% or more of the initial value even after 3000 hours. Example 3 A laminate was formed in the same manner as in Example 1, except that the metal thin film layer was made of silver and had a thickness of 150 Å. The resulting laminate had a light transmittance of 75% and an infrared reflectance of 93%. The film obtained by the accelerated heat aging method used in Example 1 was tested and maintained an infrared reflectance of 80% or more even after 2000 hours. Example 4 A laminate similar to Example 1 was constructed except that sodium hydroxide was used instead of potassium hydroxide. The resulting laminate had a light transmittance of 72% and an infrared reflectance of 93%. The obtained laminate showed good heat resistance in an accelerated heat deterioration test at 90°C, similar to that obtained when treated with potassium hydroxide. Examples 5-8

【table】

[Table] 100 parts of the organic titanate shown in Table 1 and 50 parts of alkali hydroxide were reacted at 50°C for about 60 minutes with thorough stirring, and after cooling, the mixture was heated to room temperature with continued stirring.
It was left for 24 hours. After standing, the modified tetrabutyl titanate became a reddish brown and very viscous liquid. This modified tetrabutyl titanate was diluted with a solvent consisting of 3 parts of butanol and 7 parts of n-hexane to prepare a coating solution containing 5% by weight of modified tetrabutyl titanate. This modified tetrabutyl titanate coating solution was coated on the same polyethylene terephthalate film as in Example 1 using a bar coater to obtain a first titanium oxide thin film layer having a thickness of about 230 Å to 340 Å. A metal thin film layer of silver and copper with a thickness of 180 Å was formed on the obtained titanium oxide thin film layer in the same manner as in Example 1, and then a third titanium oxide thin film layer was formed on the metal thin film layer as the first layer. It was obtained in the same manner as the titanium oxide thin film layer. The visible light transmittance of the obtained laminate was 70% or more, and the infrared light reflectance was 93%. The resulting laminate film was placed in a gear oven tester kept at 90°C, and the infrared reflectance after 2000 hours was compared and the results shown in Table 2 were obtained.

【table】

Claims (1)

[Scope of Claims] 1. In a laminate consisting of a molded product substrate and a metal thin film layer (A) covered on one or both sides with a transparent thin film layer (B), the transparent high refractive index thin film layer (B) ), at least one of which is made of a titanium oxide thin film layer (B-1) formed from an organic titanate compound, and contains a monovalent alkali metal and/or a monovalent alkali metal ion. . 2 The titanium oxide thin film layer (B-1) is titanium 1
The laminate according to claim 1, containing 0.005 to 0.2 alkali metal atoms per atom (including those in an ionic state). 3 The alkali metal and/or alkali metal ion contained in the titanium oxide thin film layer is Li,
The laminate according to claim 1 or 2, which is one or more metals or metal ions selected from the group consisting of Na, K, and Rb.