JP2005054116A - Producing method of hard coating film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a producing method of a hard coating film which metallic oxide sol has excellent coating properties to a base material, and which can form a coating film having uniformity, high hardness, excellent water repellency, photocatalytic nature and high dielectric properties. <P>SOLUTION: The producing method of the hard coating film comprises coating the oxide sol of at least one metal selected from among the groups III, IV, and V of the periodic table on a surface of the base material under an atmosphere of relative humidity of at least 50%, and then setting treating the metallic oxide sol coated on the surface of the base material. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for producing a hard coating film. More specifically, the coating film has excellent coatability to a base material of a sol to be used, is homogeneous, and has high hardness and excellent water repellency, photocatalytic properties, and high dielectric properties. It is related with the manufacturing method of the hard coating film which can form.

  In the modern living environment, there are a large number of various facilities, devices, and machinery that require water repellent treatment such as anti-fogging. In addition, such facilities, devices, and machinery are also required to have a photocatalytic function that is activated by light and decomposes harmful organic substances. For example, by forming a film having a photocatalytic function on the outer wall of a building, an outer wall having a self-cleaning function for automatically decomposing organic substances can be obtained. Similarly, a glass having a self-cleaning function can be obtained by forming a film having a photocatalytic function on a window glass of an automobile or glass of a building. Furthermore, in an electronic device, by coating a high dielectric thin film and using it as a memory, a capacitor or the like, it is possible to contribute to the enhancement of functions of these electronic devices.

  The performance or function is expressed by an oxide thin film of at least one metal selected from Groups 3, 4, and 5 of the periodic table. For example, the water repellency is expressed by a hafnia (hafnium oxide) film, a zirconia (zirconium oxide) film, or an yttria (yttrium oxide) film. The photocatalytic function is expressed by a titania (titanium oxide) film or a niobium (niobium oxide) film. The high dielectric property is expressed by a niobium film or a tantala (tantalum oxide) film.

  These thin films can be produced by applying the metal oxide sol onto the surface of a substrate and curing the coating. However, these metal oxide sols have poor applicability to metals, plastics, metal oxides, and other base materials, and have a problem that the formed coating film becomes non-uniform (coating unevenness). It was. In particular, the sol prepared using water as a solvent has a significant tendency to repel on the surface of the substrate and cannot be applied. The coating solution is required to use water as a solvent instead of an organic solvent for environmental considerations, and the above problem must be solved from the viewpoint of the production of functional materials considering the environment. It is a problem.

  The present invention solves such a conventional problem and is excellent in the coating property of the metal oxide sol on the substrate, is homogeneous, has high hardness and excellent water repellency, photocatalytic property and high dielectric property. An object is to provide a method capable of forming a film.

  In order to solve the above problems, the present inventors have studied the environment in which the metal oxide sol is applied to the surface of the base material, and as a result, the above problems are solved by setting the environment under a specific humidity. Based on this finding, the present inventors have completed the present invention.

  That is, the means for solving the above-mentioned problems of the present invention is to provide an oxide sol of at least one metal selected from Group 3, Group 4 and Group 5 of the periodic table under a relative humidity environment of at least 50%. And then curing the metal oxide sol applied to the surface of the substrate.

Preferred embodiments of the means for solving the problems of the present invention include the following methods (1) to (3) for producing a hard coating film.
(1) The manufacturing method of the hard coating film whose said base material is a metal, a plastics, or a metal oxide.
(2) The manufacturing method of the hard coating film whose said base material is the metal by which the degreasing process was carried out.
(3) A method for producing a hard coating film, wherein the metal oxide sol is an aqueous solution.

  According to this invention, the coating property of the metal oxide sol on the base material is good, it is possible to form a coating film having a uniform and high hardness, and excellent water repellency according to the type of metal, It is possible to provide a method capable of forming a coating film having one or more properties of photocatalytic property and high dielectric property.

  According to the method for producing a hard coating film of the present invention, an oxide sol of at least one metal selected from Groups 3, 4, and 5 of the periodic table is applied to the surface of a base material in a relative humidity environment of at least 50%. Next, the metal oxide sol applied to the surface of the substrate is cured.

  Examples of the metal oxide selected from Group 3, Group 4 and Group 5 of the periodic table include hafnia, titania, zirconia, yttria, Scandinavia, lantana, ceria, niobia and tantala.

Hafnia is a hafnium oxide of formula HfO _{X. X} in the formula HfO _X is an integer of 2 or less or a decimal. Hafnia may contain an organic acid such as formic acid, an alkoxide such as alcoholate, a ligand such as 2,4-pentanedione, and an inorganic acid such as nitric acid. Further, it may contain a small amount of other metal oxides. Titania is a titanium oxide of the formula TiO _{X. X} in the formula TiO _X is an integer of 2 or less or a decimal. Zirconia, zirconium oxide represented by the formula ZrO _{X. X} in the formula ZrO _X is an integer of 2 or less or a decimal. Yttria is yttrium oxide represented by the formula Y ₂ O _{X. X} in the formula Y ₂ O _X is an integer of 3 or less or a decimal. Scandinavia is scandium oxide represented by the formula Sc ₂ O _x . _X in the formula Sc ₂ O _X is an integer of 3 or less or a decimal. Lantana is lanthanum oxide represented by the formula La ₂ O _{X. X} in the formula La ₂ O _X is an integer of 3 or less or a decimal. Ceria, cerium oxide of formula CeO _{X. X} in the formula CeO _X is an integer of 2 or less or a decimal. Niobia is niobium oxide represented by the formula Nb ₂ O _x . _X in the formula Nb ₂ O _X is an integer of 5 or less or a decimal. Tantara is tantalum oxide represented by the formula Ta ₂ O _x . _X in the formula Ta ₂ O _X is an integer of 5 or less or a decimal. These metal oxides may also contain an organic acid such as formic acid, an alkoxide such as alcoholate, a ligand such as 2,4-pentanedione, and an inorganic acid such as nitric acid. Further, it may contain a small amount of other metal oxides.

    In the present invention, an oxide sol (hereinafter sometimes simply referred to as “sol”) of at least one metal selected from Group 3, Group 4 and Group 5 (hereinafter sometimes simply referred to as “metal”). ) Is not particularly limited, but for example, a metal alkoxide or metal salt is dissolved in a solvent, and a mixed solution of water and acid or a mixed solution of water and amines is added to this solution. Can be prepared by heating.

  The metal alkoxide is not particularly limited, but alkoxides having 5 or less carbon atoms, specifically, methoxide, ethoxide, propoxide, butoxide, and pentoxide are preferable. Examples of the metal salt include halides, acetates, sulfates, carbonates, nitrates, and the like, and preferred salts are halides.

    Examples of the halide include hafnium tetrachloride, hafnium tetrafluoride, hafnium tetrabromide, and hafnium tetraiodide, with hafnium tetrachloride being preferred.

  As for titanium, zirconium, yttrium, scandium, lanthanum, cerium, niobium, and tantalum, a halide similar to the hafnium halide can be cited as a preferred metal salt.

  The concentration of the metal oxide in the metal alkoxide solution or the metal salt solution is not particularly limited, but is usually 1 to 70%, preferably 1 to 50% on a mass basis. If it is less than 1%, the generated sol becomes dilute and it becomes difficult to produce a good thin film after coating. If it exceeds 70%, the concentration of the generated sol is so high that coating becomes difficult.

  The metal alkoxide solution can be easily prepared by mixing the metal alkoxide and a solvent, and the metal salt solution can be easily prepared by mixing the metal salt and a solvent. Although there is no restriction | limiting also about the conditions at the time of preparing these solutions, Usually, it stirs and mixes at 0-100 degreeC, Preferably it is 10-50 degreeC, and is prepared. At this time, an organic substance having coordination ability can also be added. Subsequently, sol is prepared by adding water and hydrolyzing. At this time, an acid or a base may be added. Moreover, you may heat as needed.

  Examples of the solvent include water, alcohols such as methanol, ethanol, butanol, isopropanol, and vinyl alcohol; ketones such as acetone, methyl ethyl ketone, and dioxane; amines and amides; and preferably used solvents are water or alcohol, particularly ethanol. Methanol or isopropanol.

  Examples of the acid include inorganic acids such as hydrochloric acid, nitric acid and sulfuric acid, and suitable inorganic acids are nitric acid and sulfuric acid. The organic acid is preferably an organic acid having 3 or less carbon atoms, and examples thereof include formic acid, acetic acid, propionic acid, glycolic acid, lactic acid, glyceric acid, oxalic acid and malonic acid. Of these, formic acid, oxalic acid, and malonic acid are particularly preferable.

  Examples of the amines include primary amines, secondary amines, and tertiary amines. As the primary amines, secondary amines such as 2-propenylamine, 2-methyl-2-propenylamine, 2-properoyloxyethylamine, and 2- (2-methylproperoyloxy) ethylamine, Di (2-propenyl) amine, di (2-methyl-2-propenyl) amine, 2-propenylamine, 2-methyl-2-propenylamine, 2-properoyloxyethylamine, and 2- (2-methylproperoyl) And tertiary amines such as N, N-dimethyl-2-properoyloxyethylamine, N, N-dimethyl-2- (2-methylproperoyloxy) ethylamine, N, N- Diethyl-2-properoyloxyethylamine, N, N-diethyl-2- (2-methylproperoyloxy ) Ethylamine, N, N-dimethyl-3-properoyloxypropylamine, N, N-dimethyl-3- (2-methylproperoyloxy) propylamine, N, N-diethyl-3-properoyloxypropylamine N , N-diethyl-3- (2-methylproperoyloxy) propylamine, N, N-dimethyl-3- (properoylamino) propylamine, N, N-dimethyl-3- (2-methylproperoylamino) Mention may be made of propylamine, N, N-diethyl-3- (properoylamino) propylamine, N, N-diethyl-3- (2-methylproperoylamino) propylamine and the like.

  Further, quaternary ammonium compounds such as tetraalkylammonium iodide, tetraalkylammonium hydroxide, tetraarylammonium iodide and tetratetraarylammonium hydroxide can also be used. Furthermore, as the amines, salts of the primary amines to tertiary amines can be used in the present invention. Such amines may be used as they are or may be used as an amine-containing aqueous solution.

  Examples of the organic substance having the coordination ability include diones such as 2,4-pentanedione and catechol, diamines such as ethylenediamine and propandiamine, and amino alcohols such as 2-aminoethanol.

  The metal alkoxide solution can be easily prepared by mixing the metal alkoxide and the solvent, and the metal salt solution can be easily prepared by mixing the metal salt and the solvent. Although there is no restriction | limiting also about the conditions at the time of preparing these solutions, Usually, it stirs and mixes at 0-100 degreeC, Preferably it is 10-50 degreeC, and is prepared. The ammonia solution or amines mixed with these solutions contains ammonia and / or amines. An aqueous solution containing ammonia, that is, aqueous ammonia, has a suitable concentration of ammonia of usually 1 to 29% by mass.

The concentration of the metal oxide in the metal alkoxide solution or the metal salt solution is not particularly limited, but is usually 1 to 70%, preferably 1 to 50% on a mass basis. If it is less than 1%, the hydroxide becomes fine particles and it becomes difficult to filter, and if it exceeds 70%, the aggregation of the hydroxide becomes prominent and filtration may become difficult.

  Subsequently, the obtained metal hydroxide is filtered off, and the target sol is formed by mixing the hydroxide with water and / or alcohol and an inorganic acid and / or organic acid. In this case, there is no special restriction on the mixing order. For example, the hydroxide and water and / or alcohol and the inorganic acid and / or organic acid may be mixed at once, the hydroxide and water and / or alcohol are mixed, and then the inorganic acid and An organic acid may be mixed. Further, the hydroxide and inorganic acid and / or organic acid may be mixed, and then water and / or alcohol may be mixed.

  The amount of water and / or alcohol and inorganic acid and / or organic acid to be mixed with the hydroxide may be an amount sufficient to peptize the hydroxide. 1 to 100 times, preferably 1 to 50 times on a mass basis. If it is less than 1 time, the concentration of metal ions becomes high and peptization becomes difficult, and if it exceeds 100 times, the concentration of metal ions in the sol decreases, which is not preferable.

  Although there is no restriction | limiting in particular in the alcohol used here, C5 or less alcohol is preferable. Specific examples include methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-methylpropanol, 2-butanol, and 2-methyl-2-propanol.

  There is no special restriction | limiting in the mixture ratio in water and / or alcohol, and an inorganic acid and / or an organic acid, When the whole quantity is 100 mass parts, an inorganic acid and / or an organic acid are usually 0.1-50 mass. Parts, preferably 1 to 20 parts by mass. If it is less than 0.1 parts by mass, the hydroxide does not pept, and if it exceeds 50 parts by mass, the base material may be damaged or deteriorated by the inorganic acid and / or organic acid used. Sometimes, the evaporation of inorganic acid and / or organic acid may adversely affect the environment, which is not preferable.

  There is no restriction on the blending ratio of both when water and alcohol are used together, and there is no restriction on the blending ratio of both when using an inorganic acid and an organic acid, but usually the total amount of acid is 100 mass. Parts, the inorganic acid, particularly nitric acid or hydrochloric acid, is 10 to 90 parts by weight, preferably 10 to 60 parts by weight.

  In this way, a metal oxide sol is prepared. In some cases, prior to mixing the hydroxide with water and / or alcohol and the inorganic acid and / or organic acid, the hydroxide is mixed with the hydroxide. It is preferable to have a step of washing with water or alcohol.

  The alcohol used for this washing is preferably an alcohol having 5 or less carbon atoms, specifically, methanol, ethanol, n-propanol, 2-propanol, n-butanol, 2-methylpropanol, 2-butanol, 2-methyl. -2-propanol and the like can be mentioned. This washing step is a step for adjusting the pH of the hydroxide and removing impurities and impurities attached to or contained in the hydroxide.

  In the present invention, a hard coating film is produced by applying a metal oxide sol prepared as described above to the surface of a substrate and then performing a curing treatment.

  There is no restriction | limiting in the base material applied, Various raw materials can be employ | adopted. For example, base materials made of plastics such as polycarbonate and polyethylene terephthalate, ordinary steel, structural alloy steel, high tensile steel, heat resistant steel, high chromium heat resistant steel, high nickel-chromium heat resistant steel Steel materials such as alloy steel and stainless steel, industrial pure aluminum, 5000 series alloys, aluminum alloys including Al-Mg series aluminum alloys and 6000 series aluminum alloys, silver-filled copper, tin-filled copper, chromium copper , Base materials made of metal materials such as various copper alloys such as chrome-zirconium copper and zirconium copper, pure titanium, drag titanium alloy and corrosion resistant titanium alloy, mullite porcelain, alumina porcelain, zircon Ceramics such as porcelain, cordierite porcelain and steatite porcelain Substrates formed from box material and the surface of the material groups formed from the metallic material can be mentioned enamel, and coated metal substrate coated by either glass lining and ceramic coating.

  As an example of the base material formed from a metal material, an exterior plate, for example, a power transmission line, a building, a sash, and, for example, an outer plate of a railway vehicle can be cited. Moreover, household base materials, such as metal daily miscellaneous goods, a kitchen, a bath, and a toilet, can also be mentioned. As an example of the base material formed from a ceramic material, metal oxides, such as an alumina and a silica, an insulator, a soot pipe, a ceramic style, and a roof tile can be mentioned, for example. Examples of the coated metal substrate include various tanks, reaction tanks, brewing tanks and daily necessities including cups, washbasins and vases.

  Other examples of the substrate include a painted surface in which a paint is applied to a metal and ceramic surface. Specific examples of the painted surface include car body surfaces of automobiles, railway vehicles, and aircraft. Examples of the base material further include outer walls of buildings including concrete walls, terracotta tile walls, mortar walls, and plaster walls. Furthermore, the said various base materials which plated the surface can also be mentioned.

  Examples of the substrate include paper, cloth, leather, and wood. Among the various types of base materials, the base material formed of the glass, the base material formed of the plastics, paper, and a composite base material thereof may be mentioned as suitable base materials. Further, these base materials may be base materials that have been subjected to a surface treatment such as coating the surface and forming a coating film.

  Examples of the method of applying the sol on the surface of the substrate include, for example, a dip method in which the substrate is immersed in the sol and slowly pulled up, a casting method in which the sol is cast on the surface of the fixed substrate, A continuous method in which the base material is immersed in the sol from one end of the tank in which the sol is stored and the base material is taken out from the other end of the tank. The sol is dropped on the rotating base material, and the sol is removed by centrifugal force acting on the base material. Examples thereof include a spinner method for casting on a substrate, a spray method for spraying a sol onto the surface of the substrate, and a flow coating method.

  When the substrate is a metal, it is preferable to apply the sol after degreasing the metal surface using a degreasing agent. Moreover, electrolytic treatment can also be performed following the degreasing treatment. This is because the sol coating property on the metal substrate can be further improved by these treatments. Examples of the degreasing agent include alcohols such as ethanol or common alkaline detergents. As the alkaline detergent, for example, a degreasing agent in which a saponifying agent or a surfactant is blended with sodium orthosilicate can be used. There is no particular limitation on the conditions of the degreasing treatment, and for example, a means for wiping the metal substrate surface with alcohol can be adopted, and the metal substrate is immersed in a degreasing agent, preferably for 1 to 5 minutes, preferably The degreasing treatment can be performed by heating to 30 to 60 ° C. and stirring.

  Thereafter, it is washed with water and dried. In the electrolytic treatment, a positive or negative electrode is placed on the base material while the base material is immersed in the degreasing solution, and an electrode opposite to the one placed on the base material as a counter electrode is placed. Electrolytic treatment is performed by energizing this for an arbitrary time. The voltage at this time may be arbitrary but is preferably 1 to 200 V, and the energization time may be arbitrary, preferably 0.1 to 60 minutes, and the temperature of the liquid may be arbitrary, but preferably 0 to 80 ° C. is there. The amount of the sol applied varies depending on the viscosity of the sol and other conditions. If a thin film having a desired thickness cannot be obtained by a single application, the application can be repeated several times.

  In the present invention, the metal oxide sol is applied to the surface of the base material in an environment of at least 50% relative humidity, and then the metal oxide sol applied to the surface of the base material is cured. It is a manufacturing method of a hard coating film.

  The relative humidity is a ratio (%) of the water vapor pressure and the saturated water vapor pressure in a specific environment. In the method for producing a hard coating film of the present invention, the metal oxide sol is at least 50% in a relative humidity environment. Specifically, it is necessary to apply to the surface of the substrate in a 50 to 100% relative humidity environment. By coating in such a humidity environment, the coating property of the sol on the surface of the base material is improved, and a uniform hard coating film having no coating film unevenness is obtained.

  In order to adjust the relative humidity to a predetermined humidity, for example, in a manufacturing method of a large-scale hard coating film, an air conditioner may be used, and in a manufacturing method of a small-scale hard coating film, The silica gel may be put in a facility such as a container to be used to absorb moisture. Moreover, it is also possible to pour warm water into equipment such as a container to be used and wipe off water to the extent that water drops remain.

  As described above, when the surface of the metal oxide sol and the substrate is applied in a relative humidity environment of at least 50%, an extremely thin water film is formed on the surface of the substrate in the humidity environment. It is presumed that the affinity between the oxide sol and the surface of the substrate is improved, and good coating properties can be obtained.

  In this way, the sol applied to the surface of the substrate in an environment of at least 50% relative humidity is then cured. This curing process may be a curing process by ultraviolet irradiation or a curing process by heating. In the curing treatment by ultraviolet irradiation, a high-pressure mercury lamp, a low-pressure mercury lamp, an excimer radar, an Nd: YAG laser, or the like can be used as the ultraviolet light source to be irradiated. By using these, ultraviolet rays can be irradiated at low cost. A very short irradiation time of 1 minute to 1 hour is sufficient. Further, the intensity of the ultraviolet rays to be irradiated is arbitrary, but for example, a range in which the plastics base material is not yellowed, altered or deformed is preferable.

  When the sol applied to the substrate surface is cured by heat treatment, the heat treatment conditions are usually 50 to 1000 ° C., preferably 50 to 600 ° C., 1 minute to 2 hours, preferably 10 minutes to Although it is 1 hour, it can also harden | cure on mild temperature conditions of 50-400 degreeC. Therefore, even when the sol is cured by heat treatment, for example, the problem that the plastics base material does not turn yellow, is not altered or deformed, and a special heat resistant base material must be selected is avoided. Is done. There is no limitation on the heating means, and means using an electric furnace, means for blowing hot air, means for placing in a heated gas, and the like are employed. The thickness of the hard coating film to be obtained can be appropriately determined according to the type of substrate and the object to be applied, but is usually selected from the range of 10 to 1000 nm.

  The hardness of the hard coating film can be evaluated by a pencil hardness method. Water repellency refers to the property of repelling water and can be evaluated by the contact angle of water droplets measured using a contact angle meter.

  The hard coating film produced by the method of the present invention has a pencil hardness of 3H to 9H or higher. The contact angle (water repellency) is 70 ° or more.

  In this way, a hard coating film excellent in sol coating properties on a substrate, having a uniform and high hardness, and having good water repellency, photocatalytic properties and high dielectric properties can be applied to various buildings, facilities, equipment and machinery. , For example, on window surfaces of automobiles, painted surfaces of automobiles, kitchen equipment, kitchen utensils, exhaust devices attached to kitchen equipment, bathing equipment, wash equipment, medical facilities, medical equipment, mirrors, glasses, etc. By forming it, it will fully fulfill its function. Further, by coating a high dielectric film as a part of an electronic device by the method of the present invention, it can be used as a high performance memory or capacitor.

Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to these examples.
(Examples 1 to 3 and Comparative Example 1)

[Preparation of hafnia sol]
Hafnium tetrachloride (5.44 g) was dissolved in water (32 g, 1.787 mol) under a nitrogen atmosphere. To this solution, 29% aqueous ammonia was added until pH 9.0 to obtain a precipitate (hafnium hydroxide). The precipitate was filtered off and washed with pure water until the filtrate reached pH 7. The washed precipitate was taken in a beaker, 32 g of pure water was added, 14 ml of formic acid was added, and the mixture was heated and stirred at 85 ° C. for 3 hours. Then, it cooled to room temperature and prepared the hafnia sol.

[Hafnia sol coating and UV irradiation treatment]
A 0.5 mm thick SUS304 cut to 5 × 5 cm was washed with ethanol, rinsed with ethanol, ethanol was removed with an air gun, and dried to prepare a substrate. A sample was prepared by applying the hafnia sol obtained in [Preparation of Hafnia Sol] to the surface of the base material by the spinner method (500 rpm / 5 seconds → 2000 rpm / 30 seconds) under the conditions shown in Table 1. Next, the coated surface was irradiated with ultraviolet rays by an ultraviolet irradiation device under the conditions shown in Table 1 to produce a hard coating film. A high pressure mercury lamp (H1000L, manufactured by Toshiba Lighting & Technology Co., Ltd.) was used as the light source. Irradiation was performed with the sample placed 9 cm below the light source. The degree of ultraviolet irradiation was 80 mW / cm ² and the irradiation time was 10 minutes.

(Example 4)

The same procedure as in Example 3 was repeated except that two coatings of hafnia sol and ultraviolet irradiation treatment were repeated to produce a two-layer hard coating.
(Evaluation)

  The applicability of the hafnia sol obtained in Examples 1 to 4 and Comparative Example 1 to the substrate and the pencil hardness and contact angle (water repellency) of the hard coating films produced in Examples 1 to 4 and Comparative Example 1 were evaluated. . The evaluation results are shown in Table 2.

  The evaluation method is as follows.

[Applicability]
The hard coating film obtained by the ultraviolet irradiation treatment was visually evaluated in the following three stages.
○: No coating film unevenness is observed as a whole.
Δ: Slight radial coating unevenness is observed at the center.
X: Coating unevenness is recognized as a whole.

〔Pencil hardness〕
Pencil hardness test According to JIS K 5600-4, a pencil scratch coating film hardness tester P-TYPE (Toyo Seiki Seisakusho) is used, and a pencil with a hardness of 6B to 9H is 45 ° with respect to the thin film at an angle of 45 ° and a load of 750 g. And scanned a distance of at least 7 mm. At least three lines were scanned at this time. The thin film surface was inspected with the naked eye (visual inspection), and the test was repeated with increasing hardness until at least two scars of 3 mm or more were generated. The hardness of the hardest pencil that did not cause scars was taken as the pencil hardness of the thin film. The visual inspection was performed while referring to the limit sample.

[Contact angle]
It measured using contact angle meter CA-D (Kyowa Interface Science Co., Ltd.).
(Examples 5 to 7 and Comparative Example 2)

[Preparation of zirconia sol]
4.0 g of chlorinated zirconium oxide octahydrate was dissolved in 55 g of 99.5% ethanol, and a mixed solution of 2.23 g of water and 13.91 g of 60% nitric acid was slowly added. Then, it stirred at 40 degreeC for 2 hours, and prepared the zirconia sol. Hereinafter, a hard coating film was produced and evaluated in the same manner as in Examples 1 to 3 and Comparative Example 1 except that the ultraviolet irradiation time was 60 minutes.

  Table 5 shows the coating properties of the zirconia sols obtained in Examples 5 to 7 and Comparative Example 2 on the base material, and the pencil hardness and contact angle (water repellency) of the hard coating films produced in Examples 5 to 7 and Comparative Example 2. 3 shows.

(Examples 8 to 10 and Comparative Example 3)

  Examples 1 to 3 and Comparative Example 1 were the same as Examples 1 to 3 and Comparative Example 1 except that the ultraviolet irradiation time was 20 minutes. The results are shown in Table 4.

(Examples 11 to 13 and Comparative Example 4)

  The same procedure as in Examples 1 to 3 and Comparative Example 1 was conducted except that the formic acid in Examples 1 to 3 and Comparative Example 1 was changed to 2.9 g of oxalic acid. The results are shown in Table 5.

(Examples 14 to 16 and Comparative Example 5)

  Examples 1 to 3 and Comparative Example 1 were the same as those of Examples 1 to 3 and Comparative Example 1 except that a nickel plating base material was used instead of SUS304 in Examples 1 to 3 and Comparative Example 1. The results are shown in Table 6.

(Examples 17 to 19 and Comparative Example 6)

  It carried out similarly to Examples 11-13 and Comparative Example 4 except having replaced with SUS304 in Examples 11-13 and Comparative Example 4 and having used the nickel plating base material. The results are shown in Table 7.

(Examples 20 to 22 and Comparative Example 7)

[Preparation of zirconia sol]
5.48 g of zirconium dichloride oxide octahydrate was dissolved in 32 g of water. 29% aqueous ammonia was added to this solution until pH 9 was reached, and a precipitate (zirconium hydroxide) was obtained. This precipitate was separated by filtration and washed with pure water because the filtrate had a pH of 7. The washed precipitate was taken in a beaker, 32 g of pure water was added, 14 ml of formic acid was added, and the mixture was heated and stirred at 85 ° C. for 3 hours. Then, it cooled to room temperature and obtained the zirconia sol.

  Application of the obtained zirconia sol and ultraviolet irradiation treatment were the same as in Examples 1 to 3 and Comparative Example 1. The results are shown in Table 8.

(Examples 23 to 25 and Comparative Example 8)

[Preparation of titania sol]
1.76 g of TiCl ₄ was dissolved in 10 g of pure water. Up to this point was performed in a nitrogen atmosphere. 29% aqueous ammonia was added to this aqueous solution until pH 9 was reached, and a white precipitate (titanium hydroxide) was obtained. This precipitate was separated by filtration and washed with pure water because the filtrate had a pH of 7. The washed precipitate was taken in a beaker, 10.0 g of pure water was added, 0.39 g of 35% hydrochloric acid was added, and the mixture was heated and stirred at 60 ° C. for 2 hours to obtain a titania sol.

  Application of the obtained titania sol and ultraviolet irradiation treatment were the same as in Examples 1 to 3 and Comparative Example 1. The results are shown in Table 9.

The photocatalytic property was evaluated by the following method.
30.0 g of a 5 ppm methylene blue solution was added to each of two petri dishes having an inner diameter of 90 mm to obtain test solutions A and B. Two sheets of the titania thin film obtained as described above were immersed in this test solution A. Test solution B is for comparison and does not perform the immersion. In this state, the absorbance of the solution was measured. Next, the test solutions A and B were arranged, and a black light (UVM-57 Funakoshi) was placed about 3 cm above the sample. The test solutions A and B were irradiated with ultraviolet rays, and the absorbance of the solution was measured every 0.5 hours for 2 hours. The illuminance of ultraviolet rays at this time was 2.7 mW / cm ² . The photocatalytic property was evaluated by the relative absorbance (%) of the methylene blue solution to the test solution B of the test solution A after 2 hours.
(Examples 26 to 28 and Comparative Example 9)

(Preparation of niobyl sol)
3.18 g of Nb (OC ₂ H ₅ ) ₅ was dissolved in 50 ml of 99.5% ethanol. To this solution, a mixed solution of 55 g of water and 1.08 g of 60% nitric acid was added with stirring. Then, it heated and stirred at 50 degreeC for 1 hour, and obtained niobia sol.

  The obtained niobia sol was applied in the same manner as in Examples 1 to 3 and Comparative Example 1. The results are shown in Table 10.

Claims (4)

  An oxide sol of at least one metal selected from Group 3, Group 4 and Group 5 of the periodic table is applied to the surface of the substrate under a relative humidity environment of at least 50%, and then applied to the surface of the substrate. A method for producing a hard coating, comprising curing the metal oxide sol.   The method for producing a hard coating film according to claim 1, wherein the substrate is a metal, a plastic, or a metal oxide.   The method for producing a hard coating film according to claim 1, wherein the substrate is a degreased metal. The method for producing a hard coating film according to any one of claims 1 to 3, wherein the metal oxide sol is an aqueous solution.