JPH037754B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for forming a titanium dioxide thin film with a controlled optical thickness on the surface of a substrate using a hydrolysis reaction in an aqueous solution. Optical thickness is the product of refractive index n and dimensional thickness d. Therefore, controlling the optical thickness (hereinafter referred to as nd) is nothing but controlling the thickness itself, but it also depends on the optical substance exhibited by the thin film. (Reflectance, interference color, etc.) are controlled by nd, so controlling nd becomes a problem. Based on its high refractive index, titanium dioxide thin films are used for decorative purposes such as coloring the surfaces of glass and ceramics (laster glazes), or coating the surfaces of mica powder (muscovite) to make pearl pigments. However, in addition to these, the present invention can also be used for optical applications such as interference filters and sunglasses using multilayer films.

[Conventional technology]

The following methods are conventionally known for forming a titanium dioxide film. The first is 1988 Patent Publication No.
A uniform titanium dioxide film can be obtained using a vacuum deposition method using ion sputtering, such as No. 12564, and the optical thickness can be controlled by observing the hue and gloss of the film formed through a transparent bell gear. However, it requires a special device, and the size of the substrate is limited by the device, and the shape of the substrate is also limited.
For example, it is not possible to uniformly form a film on a significantly concave surface such as the inner surface of a glass container. Furthermore, since it uses a vacuum device, it is not suitable for mass production based on large objects.

The second step is to form a titanium dioxide thin film on the object surface.
This method is more commonly used, and involves applying a solution of a titanium compound, such as butyl titanate or acetylaceto titanate, to the surface of the substrate. In other words, a relatively dilute solution of a titanium compound is applied to the surface of an object and thermally decomposed at the same time or after the film is formed to obtain a titanium dioxide film.The thickness of the titanium compound can be measured directly or indirectly from the reflected light from the film. It can be estimated. That is, in a method in which solution application and thermal decomposition are performed simultaneously (for example, Patent Publication No. 32007 of 1972), the interference color exhibited by the formed film directly indicates the optical thickness of the titanium dioxide thin film. In the method of forming a film of a titanium compound and then pyrolyzing it to form a titanium dioxide film, there is a certain relationship between the interference colors before and after the pyrolysis, so the interference color at the time of film formation indirectly indicates the nd value after the pyrolysis. can be known. However, with these methods, it is difficult to form a titanium dioxide film with a uniform thickness over the entire surface, especially on curved or uneven surfaces.

A more special method is to perform gas phase hydrolysis by spraying the vapor of titanium tetrasalt together with water vapor on the surface of an object, but it is difficult to control the reaction, and
A uniform titanium dioxide film cannot be obtained.

Finally, a method of producing pearl pigments by hydrolyzing mica powder dispersed in an aqueous titanium salt solution has been known for a long time (USP 3087827), and several improved methods have been disclosed, but none of them are fully published. The present invention does not provide a homogeneous titanium dioxide coating with controlled optical thickness, but rather produces a glossy coating consisting of very fine precipitated particles. For example, Patent Publication No. 3824 of 1972 describes a method of forming a titanium dioxide film on glass or other substrates, but the glossy film obtained by such a method is different from the homogeneous titanium dioxide film of the present invention. It is clear from the following explanation that it is different.

[Problem that the invention seeks to solve]

The present invention was disclosed in Patent Publication No. 6809 of 1962,
We have disclosed a method for producing metallic-like strong luster and clear interference colors using a three-layer film obtained by laminating a thin film of titanium dioxide and a thin film of silicic anhydride. However, for the reasons mentioned above, the nd It was not put into practical use due to difficulties in control. Later, he discovered a method for obtaining a uniform thickness of the silicic anhydride layer by a solution reaction, and disclosed it in Patent Publication No. 46480 of 1972.
As for the titanium dioxide layer, it has not been easy to find a method for depositing a uniform film by an aqueous reaction. That is, even if glass, ceramics, etc. are generally immersed in an aqueous solution of titanium salt and the titanium salt is hydrolyzed under various conditions, the coating formed on the surface is often opaque and does not exhibit luster. Even when a glossy film is obtained, its reproducibility is extremely poor, and the resulting film is not completely transparent and homogeneous.
Both gloss and color are inferior to those obtained by the vapor deposition method or coating method.

The reason why only a cloudy film can essentially be formed is that a large number of nuclei are generated due to hydrolysis.
While each of these grows to form a precipitate, on the surface of a foreign material such as glass, there is no condition in which the same substance as the precipitate can grow, so these nuclei grow preferentially and form microscopic particles first. It is understood that a precipitate is formed, which secondarily coagulates and deposits on the surface of glass or the like. The above-mentioned Patent Publication No. 3824 of 1972 states that ``a glass plate is inserted into a suspension of mica scales'' to ``prevent free hydrous titanium dioxide nuclei from remaining in the suspension for a long time.'' However, the purpose of the present invention cannot be achieved with such a passive method. The present inventor tried various pretreatment methods for the purpose of changing the surface of glass etc. into properties equivalent to those of the precipitate core, and finally discovered a thin film forming method in which a titanium dioxide layer is deposited as a uniform film by an aqueous solution reaction. However, we have succeeded in creating a new decorative effect not seen in conventional titanium dioxide thin film applied products using a reproducible and practical method.

[Means for solving problems]

The gist of the invention is to heat the hydroxyl-rich surface of an object made of an insoluble inorganic or organic polymeric material in an acidic dilute solution of a water-soluble titanium ester, thereby precipitating the hydrolysis products of the titanium ester on the surface. a pretreatment step of at least coating the surface; and thermal hydrolysis of the tetravalent titanium salt while the pretreated surface is in contact with a strongly acidic aqueous solution of the tetravalent titanium salt with a titanium concentration of 30 mmol or less. A method for forming a titanium dioxide thin film, comprising the step of depositing titanium dioxide on the surface by depositing titanium dioxide on the surface.

The water-soluble titanium ester used in the pretreatment step is a general term for substances obtained by the reaction of lower monohydric alcohols or polyols with titanium tetrachloride, and includes a reaction product of titanic acid gel and polyol. Lower monohydric alcohols include dichlorotitanium ester obtained by dissolving titanium tetrachloride in methanol, ethanol, isopropanol, etc., and polyols include polyols such as glycerol, erythritol, and sorbitol, alkylene glycols and polyalkylene glycols, and monosaccharides. Alternatively, there are products obtained by condensing any of the compounds belonging to disaccharides with a concentrated aqueous solution of titanium tetrachloride. The above dichloroester of monohydric alcohol can also be obtained by a condensation reaction in which a concentrated aqueous solution of titanium tetrachloride is heated with an excess amount of monohydric alcohol. In the case of a liquid polyol such as glycerol or ethylene glycol, a titanic acid gel precipitated by neutralization of a cold aqueous solution of a tetravalent titanium salt may be dispersed in an excess amount of the liquid polyol and dissolved by heating.

Regarding sugars, when easily available monosaccharides or disaccharides such as glucose and sucrose are added to a concentrated aqueous solution of titanium tetrachloride and dissolved at room temperature, hydrogen chloride is gradually released and a slightly viscous product is formed. obtain. In this case, when heated, the sugar dehydrates due to hydrochloric acid and turns black, so the reaction is carried out at room temperature.

In the case of polyols, the ratio of polyol or sugar to titanium tetrachloride is such that at least 0.1 mole of hydroxyl groups per mole of titanium is used, but it may be added in excess until unreacted polyol remains without any harm to the purpose. When heated without adding polyol, a transparent dry substance is obtained, and when water is added, it becomes transparent and redissolves, but the desired effect of the present invention cannot be obtained. Even with a small amount of polyol, such as 0.1 mole of hydroxyl groups per 1 mole of titanium, a resin-like condensate can be obtained, and a dilute solution thereof is effective in the pretreatment step of the present invention. A range of 4 moles is preferred.

All of the products obtained as described above are highly soluble in water, and the acidic solution is stable at room temperature, but when heated, it gradually becomes cloudy, and when the concentration is high, a gel precipitates. Preferably, it is stored with hydrochloric acid and used after being diluted to a titanium concentration of 10 ^-5 to 10 ^-2 mol/.

Pretreatment involves immersing the target object in the above diluted solution, heating it, coating it with the hydrolysis product of the titanium ester, and then baking preferably at a temperature below the heat distortion temperature of the object before forming a film. Let's move on to the process.

The film forming process is carried out using a strongly acidic aqueous solution of a tetravalent titanium salt such as titanium tetrachloride, titanium sulfate, titanium nitrate, sodium titanium tartrate, ammonium or potassium titanyl oxalate, etc.
It is necessary to contain less than millimole/millimol of titanium and to be strongly acidic by containing sulfuric acid, hydrochloric acid, nitric acid, or a mixture thereof.

Figure 1 shows the results of an investigation using sulfuric acid with varying concentrations of titanium and acid, using a glass plate pretreated as described above. ● indicates that a glossy film was produced but the liquid became cloudy, × indicates that the solution became cloudy without producing a glossy film, or a gel precipitated; ○× indicates that the hydrolysis reaction was significant or controlled. Indicate the case. The glass plates used were treated with titanium ester of glycerol and then baked, but the difference in pretreatment liquid is irrelevant. The relationships shown in the figure may vary somewhat depending on the type of strong acid and the presence of tartaric acid, additives such as chelating agents (e.g. ethylenediaminetetraacetic acid) or ethylenediamine hydrochloride, or cations such as aluminum or magnesium, but the basic The trends are common. That is, if the acid concentration is too low, the gel tends to precipitate and film formation does not occur. Furthermore, in a titanium concentration range of 30 mmol or less, hydrolysis is significantly or completely inhibited when the acid concentration exceeds 2N. It can be seen that there is a suitable acid concentration range for a given titanium concentration, but the range varies depending on the type of acid and the presence of additives and cannot be definitively defined. If the titanium concentration exceeds 30 mmol/m, the range of suitable acid concentration becomes narrow, which is disadvantageous for controlling the reaction.

The above-mentioned additives have the effect of suppressing the formation of precipitates and can be used to control the reaction, but their presence is not essential, and they are not very effective when the titanium concentration is high. Furthermore, although the above-mentioned cations may promote the formation of precipitates, their presence in small amounts does not prevent the selective precipitation of titanium dioxide.

Depending on the reaction temperature, a film can be formed gradually even at room temperature depending on the composition, but at temperatures below 50°C, film formation is extremely slow and is not practical.
If the reaction is carried out at a temperature of 100°C or higher using an autoclave or the like, the growth of the film will be significantly accelerated. However, the atmospheric pressure reaction has the advantage that the growth of the film can be directly monitored with the naked eye. As mentioned above, as the nd increases, the reflected light from the surface gradually changes, so the desired nd
If the reaction is stopped when the property of reflected light corresponding to , that is, the reflected light spectrum is reached, a titanium dioxide film of the desired nd can be obtained. reflected light spectrum and
nd can be determined accurately using optical theory using a spectrophotometer, but it can also be judged with sufficient accuracy for practical use by the naked eye from the hue and intensity of reflected light. In other words, for example, when the luster is sufficiently developed to form a half-mirror shape and a slight bluish tinge remains, the nd of the film is approximately
100nm, a slightly blackish silvery mirror-like shape with a maximum luster of about 140nm, and a clear yellow reflected light around 200nm. If you want even more precise control, add a large number of pretreated glass plates to the coating solution one by one at regular time intervals, and compare the time scale with the gloss/hue of the coating to find the maximum gloss. By setting a point at 140 nm and creating a scale for comparison, it is possible to control nd at least approximately in units of 10 nm.

Heating methods include indirect heating using a hot water bath, direct heating by bringing the container of the film-forming solution into contact with a heat source, and using the target object as a container and putting the film-forming solution inside it, or by putting a heat source inside the target object and forming the object. Three methods of heating the object immersed in the membrane liquid are possible. In the case of the former method of heating an object, for example, if you put the film-forming liquid in a pretreated glass container and heat it from below over a direct flame, the bottom of the container will turn pink when a uniform silvery-white glossy film is formed on the side wall surface. The result was a thick interference color film that reflected blue or green light, indicating that the film grew significantly faster in areas where the reaction temperature was locally high, suggesting the usefulness of an autoclave.

In the case of indirect heating, uniform temperature conditions can be obtained, so there is an advantage that a film of uniform thickness can be obtained over the entire surface. If there is a trace amount of impurity in the reaction system, the film forming solution will gradually become cloudy, but usually it will become cloudy.
There is no significant effect on film formation up to 300 nm. Optical calculations show that the most effective nd of the titanium dioxide layer in the multilayer film is between 100 and 175 nm.
One reaction is enough. As mentioned above, if an autoclave is used, it is almost certain that a thicker film can be obtained in one reaction, but even in normal pressure reactions, it is necessary to use highly purified dilution water or to make the film-forming solution transparent. If the reaction is continued with a fresh one, an even thicker film can be obtained. In the middle of the process, I masked a part of the surface with synthetic resin, etc. to intentionally create different parts of the nd.
It can also be applied to patterns.

[Effect]

The pretreatment using the water-soluble titanium ester is
A method that uniformly forms a titanium-rich layer on the surface of an object, in which the hydroxyl groups on the surface and the titanium ester react and bond, and an extremely thin layer of hydrolysis products is subsequently formed on top of it. it is conceivable that. That is, when glass, ceramics, silica, etc. whose surfaces have been purified with sodium hydroxide, etc., are immersed in the acidic pretreatment solution, the surfaces become covered with hydroxyl groups, and upon heating, they change to titanium-rich surfaces as described above. As a result, it is thought that a surface condition capable of growth is obtained, similar to the surface of the nucleus that is generally produced by thermal hydrolysis of titanium salts.

Such surface properties do not change even if baked at temperatures above 400°C, and the titanium salt aqueous solution undergoes hydrolysis when it comes into contact with a strongly acidic tetravalent titanium salt aqueous solution as it is or after baking. When heated to a temperature, the nuclei for the growth of the precipitate are already present on the surface of the object itself as growth nuclei, so that, in the absence of any impurities, the rate of hydrolysis and the rate of consumption of the titanium salt by the growth of a film on the surface will be reduced. As long as the balance is maintained, hydrolysis proceeds selectively only on the surface, and it is presumed that epitaxial growth of a pure film similar to the surface of a crystal occurs. Considering that when baking is performed in the pretreatment step, the glossy film that is produced will not change even if it is further baked, and also because the hydrolysis reaction is thermal hydrolysis rather than neutralization. It is interpreted that the growing film is not hydrated titanic acid but titanium dioxide itself.

Further, the above-mentioned surface rich in hydroxyl groups can be produced by forming a layer rich in hydroxyl groups such as a silicic acid coating on the surface, thereby converting the surface which is not originally rich in hydroxyl groups. In the case of organic polymer substances, the method of the present invention can be applied not only to those containing a large number of hydroxyl groups such as cellophane, but also to synthetic resins as long as hydroxyl groups are introduced onto the surface by a known modification method. Of course something is to be expected.

Furthermore, the present invention can be practiced using metals as long as the surface is completely coated with a sufficiently dense silicic acid coating or silicate coating.

〔Effect of the invention〕

As described above, according to the method of the present invention, it is possible to freely control the optical thickness and form a uniform titanium dioxide film easily and with good reproducibility, regardless of surface irregularities, and furthermore, the surface It is also possible to design by consciously manipulating the optical thickness distribution on the top.
There are essentially no restrictions on the shape or size of the surface on which the film is formed. Furthermore, if this is made into a multilayer film, it can be applied not only to decorative purposes such as providing gloss and color, but also to interference filters, sunglasses, etc.

〔Example〕

The following examples will specifically explain the scope of the present invention, but it covers the entire scope of the present invention due to the variety of water-soluble titanium esters that can be used for pretreatment, the diversity of target objects and application ranges, and the vast possibilities of film-forming solution compositions. Since it would take a huge amount of paper to do so, the description will be limited to only the main examples, but it should be noted that the scope of the claims of the present invention is not limited to the following examples.

Example 1 (1) Preparation of titanium tetrachloride aqueous solution 35 g of titanium tetrachloride (1st grade reagent) was quickly weighed into a 200 ml Erlenmeyer flask, and purified water (deionized water is hereinafter abbreviated as pure water) in a ventilator. ) Gradually drip 20g. At first it becomes a yellowish-white mass, but once the entire amount of pure water has been added, it becomes a dark yellow and slightly viscous solution.

The titanium concentration by gravimetric analysis was 3.5 mol/.

(2) Preparation of glycerol titanium ester Take 3 g of the above titanium tetrachloride aqueous solution in a 50 ml beaker, add 3.6 g of glycerol to dissolve it, and heat it using a hot plate in a ventilator. It will boil and turn into water vapor and chloride. Releases hydrogen.
After boiling, remove volatiles while stirring.
Once it becomes starch syrup-like, leave it to cool and solidify. 1ml pure water
Add and reheat to dissolve, and further dilute with pure water to make a total of 300ml.

(3) Pretreatment of glass plates Cut a glass plate for windows into pieces approximately 5 cm x 7 cm in size, place in a 300 ml beaker, and fill with 1N sodium hydroxide until the glass plate is completely immersed. When processing a large number of items at once, use an appropriate spacer to prevent the surfaces from coming into contact with each other, and place them in a boiling bath for about 20 minutes.
After heating for 1 minute, wipe the surface thoroughly with a sponge in clean water, and do not touch the surface with your fingers for about 1 minute.
Cut into strips of cm x 5 cm and store in pure water. This glass plate was used in all of the following examples up to Example 9.

Put 10 ml of pure water in a test tube, and add 1 ml of the solution of the reaction product of glycerol and titanium tetrachloride with a dropper.
(approx. 0.05ml) and 4 drops of 10% diluted hydrochloric acid (approx.
0.2ml) and stir, then add the glass plate mentioned above. Heat it in a boiling bath for about 30 minutes, then discard the liquid, wash it with clean water, then wash it with pure water, air dry it, place it on a wire mesh, bake it in an electric heater for about 15 minutes, and then slowly cool it.

(4) Generation of titanium dioxide film Put 3 ml of 50% sulfuric acid and 1 drop (approximately 0.05 ml) of the titanium tetrachloride aqueous solution mentioned above into a 100 ml volumetric flask, make up to 100 ml with pure water, and prepare a solution with a titanium concentration of 1.75 mmol/. . Place the pretreated glass plate in a test tube and add this solution until the entire plate is submerged.
Fill a 300ml beaker with hot water, place it on a hot plate, and when the liquid reaches 80°C or higher, place a test tube in the beaker and heat it indirectly. After keeping the melting temperature above 80℃ for about 15 minutes, a bluish-white reflected light appears on the glass plate surface. As the heating continues, the luster gradually increases,
In about 30 minutes, it becomes a silvery-white half-mirror shape. Even if you take out the glass plate, wash it with water, and wipe the surface, the glossy film is firmly bonded to the surface and will not peel off. Further, it was placed on a wire mesh and heated for 15 minutes over direct heat in an electric heater, but no change was observed in gloss or transparency.

Example 2 In Example 1 (2), 100 ml of a titanium ester solution was prepared using 1.2 g of ethylene glycol instead of glycerol. A glass plate was pretreated using this solution in the same manner as in Example 1, and then an attempt was made to generate a titanium dioxide film (hereinafter referred to as film formation treatment).
The same results as in Example 1 were obtained.

Furthermore, similar attempts were made using equivalent amounts of propylene glycol, butanediol, diethylene glycol, and triethylene glycol in place of ethylene glycol, but results were not significantly different.

Example 3 In (2) of Example 1, 0.2 g of white sugar was used instead of glycerol, and the solution was gradually dissolved at room temperature and then dissolved in 100 ml of pure water. The same pretreatment and film forming treatment as in Example were performed. It was confirmed that a glossy film was formed on the glass surface.

Example 4 In (2) of Example 1, 1.2 g of sorbitol was used instead of glycerol and dissolved by heating.
After dissolving the resinous material obtained by removing water and hydrogen chloride released by condensation in 100 ml of pure water, this solution was used for pretreatment and film formation in the same manner as in Example 1. It was confirmed that the following results could be obtained.

Example 5 In (2) of Example 1, the amount of glycerol was changed to 0.6 g.
Similarly, a solid product was obtained when the amount was reduced to 0.1 g. Dissolve the latter product in 100 ml of pure water,
40ml of hydrochloric acid was added and stored in a glass bottle. Pretreatment and film formation were performed in the same manner as in Example 1 using a solution prepared by diluting 2 ml of this solution with 300 ml of pure water, and similar results were obtained.

Example 6 A large number of glass plates pretreated according to Example 5 were prepared, and a comparative test of film forming treatment was conducted in the same manner as Example 1 by changing the component ratio of the three-component system consisting of pure water, titanium tetrachloride, and sulfuric acid. The results shown in FIG. 1 were obtained. The illustrations are as described in the detailed description of the invention.

Example 7 In (4) of Example 1, titanium sulfate was used instead of titanium tetrachloride, and the titanium concentration was 2.5 mmol/.
A film formation process was performed in the same manner as in Example 1 using a solution with a hydrochloric acid concentration of 0.3N, and similar effects were confirmed.

Example 8 (1) Preparation of titanic acid gel Titanium tetrachloride aqueous solution prepared in (1) of Example 1
Dilute 1 g with 50 ml of cold pure water, gradually add 12 ml of cooled 5% sodium hydroxide solution to separate the resulting gel precipitate, wash with pure water, and transfer to a beaker.

(2) Preparation of sodium titanium tartrate solution Add 2.3 g of tartaric acid and 12 g of sodium hydroxide to the above separated precipitate and stir. Furthermore, place the beaker in a hot water bath until the entire solution is dissolved, and then strain until the total volume of the liquid is reduced.
Add pure water through paper until the volume reaches 30ml.

(3) Preparation of ammonium titanyl oxalate solution Add 0.4 g of ammonium oxalate to the precipitate obtained in (1) above, dissolve by heating, and dilute to 30 ml by filtration.

(4) Film formation treatment Add 0.5 ml of each of the solutions obtained in (2) and (3) above to 50% sulfuric acid.
0.5 ml and 20 ml of pure water were added to make a solution with a titanium concentration of about 2.8 mmol/g, and treated in the same manner as in Example 1, and it was confirmed that a glossy film could be obtained in each case.

Example 9 Glass plates pretreated according to Example 5 were placed in five test tubes, and a sulfuric acid solution of sodium titanium tartrate having the same composition as (4) of Example 8 was added.
The bath is heated in a hot water solution using a 300 ml beaker while keeping it in a boiling state, and the bath is occasionally replenished with hot water to perform the film formation process. After about 20 minutes, when a bluish glossy film has formed, one test tube is taken out and left to cool. After about 10 minutes, when the blue color disappears, try the next one.
Further, when a blackish silvery mirror-like luster is reached, take out the third, and when the glossy film becomes yellowish, take out the fourth, leave to cool, and continue even when the liquid becomes cloudy until it turns golden. When it reaches the end, take out the last one. After each glass plate is left to cool, it is washed with water and then baked at approximately 400℃ for 5 minutes. The optical thickness is approximately 100 nm, approximately 120 nm, and approximately
Titanium dioxide films of 140 nm, about 170 to 180 nm and about 200 nm are obtained. Depending on the purity of the liquid, the golden titanium dioxide film may be slightly cloudy.

Example 10 Tempered glass for windows is cleaned according to Example 1 and then pretreated according to Example 5. This was subjected to a film forming process according to Example 9, and when the liquid became cloudy, it was replaced with a fresh one and the process was continued for about 2 hours, resulting in a blue-green film through yellow, pink, purple, and blue. When washed and dried, the clarity is slightly lower than when it is in water, but a template glass that exhibits transparent blue-green reflected light and pink transmitted light is obtained. In this way, arbitrary nd
A major feature of the present invention is that a uniform titanium dioxide film of 100% can be obtained.

Example 11 A number of glass plates were purified according to Example 1, washed with fresh water and pure water while still in a beaker, and then filled with a pretreatment liquid having the composition of Example 5.
Boil in a hot water bath in a steamer for 30 minutes.
After washing with clean water and pure water, put it back into the beaker.
A film-forming solution having the composition of Example 9 is filled and film-forming processing is carried out in the same manner as in Example 9, while maintaining the transparency of the solution, until a golden-yellow glossy film is formed. After cooling, the beaker is washed with water and put back into the beaker, filled with 1N aqueous sodium chloride, and heated again in a hot water bath for 30 minutes.The golden-yellow film peels off and separates into the liquid in the form of gold foil.

The glass plate is removed and the foil is allowed to settle and then decanted and washed to obtain a gold leaf slurry-like product. Add acrylic emulsion, mix gently and apply to paper to get a golden coating.

Example 12 A wine glass is placed in a 500 ml beaker, 1N sodium hydroxide is added to completely immerse the glass, and the surface is purified in a boiling water bath for 30 minutes. Next, use a sponge in clean water to wipe the surface without touching it with your fingers, then return it to the washed beaker and rinse with pure water.

It is filled with a pretreatment liquid having the composition of Example 5, treated in a boiling bath for 30 minutes, then allowed to cool, washed with water, and air-dried. Next, it is placed on a wire gauze and baked for 15 minutes in a furnace at about 400°C, and after being slowly cooled, it is returned to the beaker, a film forming solution having the composition of Example 9 is added, and the beaker is placed on a hot plate and heated. When the liquid begins to boil, cover the top of the beaker with a watch glass and pour cold water into the watch glass. A silver-white titanium dioxide film forms on the entire surface of the glass in about 40 minutes. By wiping off the water after rinsing with water, you can obtain a wine glass with a cool appearance that never existed before, and when you pour wine into it and then drink it, as the water evaporates, the extract concentrates and forms a thin film that forms. Color appears.

Example 13 After forming the titanium dioxide film in Example 12, only the liquid was removed and replaced with a solution having the following composition.

Sodium silicate No. 3 (manufactured by Fuji Chemical) 1.0g Ammonium chloride 1.5g Pure water 500ml After keeping the temperature close to the boiling point for about 2 hours, discard the liquid and wash with water, then rinse with pure water, and repeat the procedure of Example 5 as above. It is filled with a pre-treatment liquid having the same composition, boiled for 30 minutes, and baked, and then a titanium dioxide film is laminated again using a film-forming liquid having the composition of Example 9. The initially silvery-white glossy film maintained much more gloss than in Example 9, and the hue of the reflected light changed to yellow, copper, pink, and purple, and suddenly became clearer when it turned blue-green. If you stop the reaction in this state, take it out, wash it with water, and bake it,
The result is a glass that shines in a clear blue-green color that cannot be seen in the case of a single-layer film, and the areas other than the highlights are transparent and pink.

If the combination of the nd of the outer titanium dioxide layer and the nd of the intermediate layer is selected appropriately, various combinations of extra colors can be created, such as those that shine golden yellow with a transparent purple color, and those that shine green with a transparent magenta color. is obtained. If the above steps are repeated one more time to form a 5-layer film, the gloss will be even stronger and the color more vivid.

Example 14 When a white porcelain vessel is used as the substrate instead of glassware in Example 13, the transmitted light is reflected on the white base and becomes the ground color, for example, purple porcelain with golden highlights is obtained, and the raster It is much clearer than glaze.

Example 15 Cellophane paper was washed with detergent, then thoroughly wiped with a cloth soaked in sodium bicarbonate water, rinsed with pure water, immersed in a pretreatment solution having the composition of Example 1, and heat-treated for about 30 minutes.
When the film was washed with water and subjected to film formation treatment in the same manner as in Example 1, a glossy film was formed on the cellophane paper.

Example 16 Nachi Kuroishi is immersed in a 7-fold diluted No. 3 sodium silicate solution (manufactured by Fuji Chemical) heated to 100°C and pulled up to form a film of sodium silicate on its surface. If you keep the temperature of the stone itself at 100℃, you can obtain a dry coating immediately after pulling it up.
% solution and boil for 30 minutes to fix. When a blue-green three-layer film is formed on the surface-treated stone in the same manner as in Example 13, beads exhibiting a blue-green metallic luster are obtained.

[Brief explanation of the drawing]

FIG. 1 is a concentration relationship diagram showing the results of film formation in Example 6 with various combinations of titanium concentrations from 0.4 to 35 mmol/and sulfuric acid concentrations from 0.05 to 4N. In the figure, ○ indicates that the liquid is transparent and a glossy film is formed, ● indicates that the liquid is cloudy but a glossy film is formed, × indicates that the liquid is cloudy or precipitated and no glossy film is formed, and ○× indicates that the hydrolysis reaction is significantly or completely suppressed. The cases are shown below.

Claims (1)

[Claims] 1. By heating the hydroxyl-rich surface of an object made of an insoluble inorganic substance or an organic polymeric substance in an acidic dilute solution of a water-soluble titanium ester, a hydrolysis product of the titanium ester is precipitated on the surface, and the surface is coated. A pre-treatment step for coating;
The pretreated surface is brought into contact with a strongly acidic aqueous solution of a tetravalent titanium salt having a titanium concentration of 30 mmol or less, and thermal hydrolysis of the tetravalent titanium salt is allowed to proceed, thereby depositing titanium dioxide on the surface. A method for forming a titanium dioxide thin film, the method comprising a step of forming a film to cause precipitation.