JP2010150079A - Method for forming inorganic film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for forming an inorganic film, capable of yielding the inorganic film by a heat-treatment at a low temperature and a simple method, wherein the resulting inorganic film is excellent in adhesion to a substrate and transparency, has uniform thickness and is microscopically smooth. <P>SOLUTION: In the method for forming an inorganic film, a coating solution for forming an inorganic film is atomized and applied to a substrate so as to form the inorganic film. The coating solution comprises: stannic acid (A); at least one compound (B) chosen from the group consisting of ammonia, tetramethylammonium hydroxide and an amine that has a boiling point of ≤150°C under atmospheric pressure and shows solubility of ≥5 mass% in water at 20°C; water (C); and a solvent (D) that has a boiling point of 60-120°C under atmospheric pressure and shows water solubility of ≥40 mass% at 20°C. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an inorganic film forming method.

  The inorganic film is used for a transparent electrode of a display element such as a liquid crystal display element and a plasma display panel, an antireflection film for display, and a heating element of a window glass of a vehicle, an aircraft, a building, or the like.

  The inorganic film is usually formed by a film forming method such as sputtering, vacuum deposition, or CVD.

  The sputtering method is the most well-known film forming method for forming an inorganic film, particularly an inorganic transparent conductive film. Sputtering is a method in which plasma is generated by discharge in a vacuum, and the target material jumps out when cations in the plasma collide with the surface of the target. This is a film forming method for forming an inorganic film by deposition. The sputtering method is advantageous in that an inorganic film having a wide range of materials can be formed, an inorganic film having a complicated composition can be formed, and a uniform film can be formed. However, the sputtering method has problems in that the apparatus is complicated and expensive, vacuum conditions are required, and it is difficult to form a large-area film.

  The vacuum evaporation method uses the fact that a metal or metal oxide evaporates by resistance heating or the like of the metal or metal oxide in a vacuum, and the evaporated metal or metal oxide is deposited on the heated substrate. This is a film forming method for forming an inorganic film. The vacuum deposition method is advantageous in that a uniform film can be formed. However, the vacuum deposition method has problems in that the apparatus is complicated and expensive, vacuum conditions are required, it is difficult to form a film with a large area, and heating at a high temperature is required.

  The CVD method is a film forming method in which a raw material is supplied in a gaseous state to the substrate surface and uses a chemical reaction of the raw material on the heated substrate surface, and an inorganic film is formed by the chemical reaction. The CVD method is advantageous in that the apparatus is simple and inexpensive. However, the CVD method has a problem in that heating at a high temperature is required.

  In contrast to these film forming methods, there is a method in which a liquid raw material is applied to a substrate to form an inorganic film. One of the methods is the sol-gel method, in which metal alkoxide is used as a starting material, and this is chemically reacted to obtain colloidal polymer particles (sol). It is the synthesis | combining method of the inorganic material made to equalize. When the inorganic film is formed by the sol-gel method, the sol is applied on the substrate and then gelled, dried, or the like. The sol-gel method is advantageous in that the apparatus is simple and inexpensive and can be performed at normal pressure. However, the sol-gel method has problems in that it usually requires heating at a high temperature and shrinkage easily occurs due to heat treatment. In some cases, heat treatment at a low temperature is possible, but in this case, there is a problem in that an organic component tends to remain in the formed film.

  In addition, as another method for forming an inorganic film by applying a liquid raw material to a substrate, Patent Document 1 discloses an invention of an ammonium stannate solution as a liquid raw material, and after spin-coating the solution on a substrate, An invention relating to a method of forming a transparent conductive film by heating is disclosed. The present invention is advantageous in that an inorganic film can be easily formed. However, the present invention has problems in that it is difficult to form an inorganic film having a uniform film thickness and inferior in microscopic smoothness.

  Patent Document 2 discloses an invention relating to an antistatic agent comprising an aqueous ammonium stannate aqueous solution and an aqueous polyurethane resin emulsion in which the isocyanate component is an alicyclic isocyanate, and an invention relating to a thermoplastic resin molded article coated with the antistatic agent. It is disclosed. The present invention is advantageous in that an antistatic film can be easily formed without requiring heating at a high temperature. However, the antistatic film formed according to the present invention is different from the inorganic film because an organic component is present in a large amount in the antistatic film.

  In Patent Document 3, a water-soluble polymer having a polar group is further dissolved in an aqueous solution containing stannic acid as a main component in the presence of at least one compound selected from the group consisting of ammonia and a water-soluble amine. The invention relates to a coating solution for forming a transparent conductive tin oxide film, and a method for producing a transparent conductive tin oxide film in which the coating solution is applied to a substrate, and then dried and baked. The present invention is advantageous in that a tin oxide film excellent in conductivity and transparency can be formed. However, this invention has a problem in that heat treatment at a high temperature is necessary to remove the water-soluble polymer.

JP-A-1-257129 JP-A-7-166092 JP 2001-210156 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is to have excellent adhesion to a substrate, heat treatment at a low temperature and a simple method, transparency, uniform film thickness, An object of the present invention is to provide an inorganic film forming method capable of obtaining an inorganic film having good visual smoothness.

  As a result of intensive studies on the method for solving the above problems, the present inventors have found that a coating solution for forming an inorganic film containing a specific compound such as stannic acid and ammonia, water, and a specific solvent is fogged on the substrate. The inventors have found that the above-mentioned problems can be solved by chemical coating, and have completed the present invention.

  That is, the present invention is at least selected from the group consisting of stannic acid (A), ammonia, tetramethylammonium hydroxide, and an amine having a boiling point of 150 ° C. or lower under atmospheric pressure and 5 mass% or more dissolved in 20 ° C. water. For forming an inorganic film containing one compound (B), water (C), and a solvent (D) having a boiling point of 60 ° C. to 120 ° C. under atmospheric pressure and 40% by mass or more dissolved in water at 20 ° C. The present invention relates to an inorganic film forming method for forming an inorganic film by atomizing a coating solution onto a substrate.

  According to the present invention, an inorganic film having excellent adhesion to a substrate, transparency, uniform film thickness, and good microscopic smoothness can be obtained by a heat treatment at a low temperature and a simple method.

  The inorganic film forming method of the present invention includes a group consisting of stannic acid (A), ammonia, tetramethylammonium hydroxide, and an amine having a boiling point of 150 ° C. or less under atmospheric pressure and 5% by mass or more in 20 ° C. water. And at least one compound (B) selected from the group consisting of water (C), and a solvent (D) having a boiling point of 60 ° C. to 120 ° C. and at least 40% by mass in 20 ° C. water under atmospheric pressure. This is an inorganic film forming method in which an inorganic film is formed by atomizing a coating solution for forming an inorganic film onto a substrate.

Inorganic film-forming coating solution The inorganic film-forming coating solution used in the inorganic film-forming method of the present invention has stannic acid (A), ammonia, tetramethylammonium hydroxide, and a boiling point of 150 ° C. or less under atmospheric pressure and 20 At least one compound (B) selected from the group consisting of amines dissolved in water at 5% by mass or more in water at 0 ° C. [Hereinafter, it may be abbreviated as “compound (B).” ], Water (C), and a solvent (D) having a boiling point of 60 ° C. to 120 ° C. and at least 40% by mass in water at 20 ° C. [hereinafter abbreviated as “solvent (D)”. is there. ] Is contained.

  As the at least one compound (B) selected from the group consisting of ammonia, tetramethylammonium hydroxide, and an amine having a boiling point of 150 ° C. or lower under atmospheric pressure and 5 mass% or more dissolved in water at 20 ° C., For example, ammonia, tetramethylammonium hydroxide (TMAH), ethylenediamine (boiling point: 117.0 ° C., solubility in water: free mixing), triethylamine (boiling point: 89.4 ° C., solubility in water: 10.1% by weight dissolution) Etc. In the above examples, the boiling point is the boiling point under atmospheric pressure, and the solubility in water is the solubility in water at 20 ° C. Among these compounds (B), ammonia is preferable because it does not contain an organic component and cannot remain in the inorganic film where the organic component derived from the compound (B) is formed.

Here, free mixing in the present invention means that it can be mixed with the liquid of interest (water in the present invention) at an arbitrary ratio.
In the case other than the above compound (B), that is, in the case of an amine having a boiling point greater than 150 ° C. under atmospheric pressure, the amine may remain as an organic component in the inorganic film formed according to the present invention. Since it becomes high, it is not preferable. In addition, in the case of an amine having a solubility in water at 20 ° C. of less than 5% by mass, the amount dissolved in water is small, so that the pH of the coating solution for forming an inorganic film is sufficient to dissolve stannic acid (A). This is not preferable because it is difficult to increase the thickness and the stannic acid (A) is hardly dissolved in the coating solution for forming an inorganic film.

  Content of at least one compound (B) selected from the group consisting of the ammonia, tetramethylammonium hydroxide, and an amine having a boiling point of 150 ° C. or lower under atmospheric pressure and 5 mass% or more dissolved in water at 20 ° C. Is not particularly limited as long as it is an amount capable of dissolving stannic acid (A) in the coating solution for forming an inorganic film.

  Examples of the solvent (D) having a boiling point of 60 ° C. to 120 ° C. and soluble in water of 20 ° C. or more in water at 20 ° C. include ethanol (boiling point: 78.3 ° C., solubility in water: free mixing). ), Isopropanol (boiling point: 82.3 ° C., solubility in water: free mixing), allyl alcohol (boiling point: 96.90 to 96.98 ° C., solubility in water: free mixing), t-butanol (boiling point: 82.5) ° C, solubility in water: free mixing), propargyl alcohol (boiling point: 115.0 ° C, solubility in water: free mixing), 1-propanol (boiling point: 97.2 ° C, solubility in water: free mixing), methanol (boiling point) : 64.7 ° C, solubility in water: free mixing), 3-methyl-1-butyn-3-ol (boiling point: 104.0 ° C, solubility in water: free mixing) A boiling point of 60 ° C. to 120 ° C. under atmospheric pressure and alcohol are dissolved in 20 ° C. water 40 mass% or more and the like; tetrahydrofuran (boiling point: 65.0 ° C., solubility in water: free mixture), and the like. In the above examples, the boiling point is the boiling point under atmospheric pressure, and the solubility in water is the solubility in water at 20 ° C. From the viewpoint that an inorganic film having better microscopic smoothness can be formed, an alcohol having a boiling point of 60 ° C. to 120 ° C. under atmospheric pressure and 40% by mass or more in 20 ° C. water is preferable, and ethanol and / or Isopropanol is more preferred.

  In the case other than the above compound (D), that is, in the case of a solvent having a boiling point different from 60 ° C to 120 ° C under atmospheric pressure, or in the case of a solvent having a solubility in water at 20 ° C of less than 40% by mass. This is not preferable because the adhesion of the formed inorganic film to the substrate and the microscopic smoothness are inferior.

  The content of the solvent (D) having a boiling point of 60 ° C. to 120 ° C. and at least 40% by mass dissolved in 20 ° C. water is not particularly limited, but the inorganic film forming coating is not limited. Preferably it is 40-240 mass% with respect to the water contained in a solution, More preferably, it is 60-160 mass%. These ranges are significant in that an inorganic film having better microscopic smoothness can be formed.

The content of the stannic acid (A) is not particularly limited, but is preferably 0.1 to 15% by mass in terms of SnO ₂ with respect to the coating solution for forming an inorganic film, More preferably, it is 0.5-5 mass%. The lower limit of these ranges is significant in terms of coating efficiency. The upper limit of these ranges is significant in terms of storability.

  The pH of the coating solution for forming an inorganic film is not particularly limited, but is preferably pH 9.5 to 12.0, and more preferably pH 10.0 to 11.0. These ranges are significant in that the dissolution of stannic acid (A) is facilitated, and a stable coating solution for forming an inorganic film with almost no precipitation is obtained.

  The said coating solution for inorganic film formation may contain metal components other than tin in the range with the effect of this invention. Examples of metal components other than tin include antimony, niobium, and bismuth. Although content of these metal components other than tin is not specifically limited, Preferably it is 0.1 to 20% by atomic ratio with respect to Sn.

  The coating solution for forming an inorganic film is substantially free of organic components that are not removed by volatilization, evaporation, boiling, decomposition, or the like when forming the inorganic film according to the present invention. The inorganic film formed according to the present invention is substantially free of organic components that are not removed by volatilization, evaporation, boiling, decomposition, etc. when the inorganic film-forming coating solution forms the inorganic film according to the present invention. An inorganic film substantially free of organic components is obtained.

Here, in the present specification, “substantially does not contain” means that in the case of the coating solution for forming an inorganic film, the content of the component with respect to the value obtained by converting the contained stannic acid (A) into SnO ₂ . It means that the abundance is 5% by mass or less, preferably 1% by mass or less, particularly preferably 0.1% by mass or less. In the case of an inorganic film formed according to the present invention, the amount of the component is 5% by mass or less, preferably 1% by mass or less, particularly preferably 0.1% by mass or less, based on the inorganic film. It means that there is.

  Specific examples of organic components that are not removed by volatilization, evaporation, boiling, decomposition, etc. when forming an inorganic film according to the present invention include organic resins and surfactants. Examples of the organic resin include polyethylene resin, polypropylene resin, polyester resin, polystyrene resin, polyvinyl chloride resin, polyamide resin, polycarbonate resin, polybutadiene resin, polyacetal resin, acrylic resin, melamine resin, urea resin, polyurethane resin, and epoxy resin. , Polyvinyl alcohol, cellulose acetate and the like.

  The solvent (D) having a boiling point under atmospheric pressure of 60 ° C. to 120 ° C. and dissolved in 40% by mass or more in water of 20 ° C. is an organic component, but when forming an inorganic film according to the present invention. It is removed by volatilization, evaporation, boiling, etc.

  The inorganic film-forming coating solution may contain organic components as long as they are organic components that are removed by volatilization, evaporation, boiling, decomposition, or the like when the inorganic film is formed according to the present invention. Examples of the organic component include a solvent having a boiling point of 60 ° C. to 120 ° C. under atmospheric pressure and 40% by mass or more in 20 ° C. water, and a boiling point of 120 ° C. under atmospheric pressure, for example. The following organic solvents are mentioned.

  The method for producing the inorganic film-forming coating solution is not particularly limited. For example, at least one selected from the group consisting of stannic acid (A), ammonia, tetramethylammonium hydroxide, and an amine having a boiling point of 150 ° C. or lower under atmospheric pressure and 5 mass% or more dissolved in water at 20 ° C. After preparing an aqueous solution (so-called ammonium stannate aqueous solution or the like) containing the compound (B) and water (C), the aqueous solution has a boiling point of 60 ° C. to 120 ° C. and 20 ° C. under atmospheric pressure. The manufacturing method which mix | blends with the solvent (D) which melt | dissolves 40 mass% or more in 1 is mentioned.

  At least one compound selected from the group consisting of the stannic acid (A), ammonia, tetramethylammonium hydroxide, and an amine having a boiling point under atmospheric pressure of 150 ° C. or less and 5% by mass or more dissolved in 20 ° C. water. The preparation method of the aqueous solution containing (B) and water (C) is not particularly limited. For example, as disclosed in the invention described in JP-A No. 2001-210156, after a tin compound is hydrolyzed to obtain a hydroxide of tin (stannic acid), it is filtered off as necessary, The preparation method which dissolves in water in presence of said compounds (B), such as ammonia, and obtains a target object is mentioned. The tin compound is not particularly limited as long as it can be hydrolyzed to obtain a hydroxide, and examples thereof include halides such as stannic chloride, organotin halides, stannates, and esters containing tin. In addition, as disclosed in the invention described in JP-A-1-257129, a gel is prepared by reacting the halide with alkali hydrogen carbonate or ammonium hydrogen carbonate, and then washing or the like is performed as necessary. The preparation method which removes an impurity by this, and melt | dissolves this gel in water in presence of said compounds (B), such as ammonia, and obtains a target object is mentioned. Examples of the alkali hydrogen carbonate include potassium hydrogen carbonate and sodium hydrogen carbonate.

Inorganic film forming method The inorganic film forming method of the present invention is an inorganic film forming method in which an inorganic film is formed by atomizing and coating the coating solution for forming an inorganic film on a substrate.

  The substrate used in the present invention is not particularly limited. For example, a glass substrate, a metal substrate, a plastic substrate, etc. are mentioned. Specific examples of the glass substrate include soda glass, quartz glass, and borosilicate glass. An example of the metal substrate is an aluminum substrate. Specific examples of the plastic substrate include acrylic resin, polyester resin [polyethylene terephthalate (PET), polybutylene terephthalate (PBT), etc.], epoxy resin, phenol resin, silicone resin, polycarbonate resin, polyvinyl chloride resin, ABS. Examples thereof include resin, FRP, polyethylene resin, polypropylene resin, and a plastic substrate made of rubber. Moreover, the shape of these board | substrates is not limited, for example, a film form, a plate shape, a molded article etc. are mentioned.

  The substrate is preferably a plastic substrate, more preferably a polyester resin substrate, and particularly preferably polyethylene terephthalate. Since the inorganic film can be formed by the heat treatment at a low temperature in the inorganic film forming method of the present invention, these plastic substrates can be used. By using a plastic substrate in the present invention, an inorganic film can be formed on the surface, and an article that is light and excellent in transparency and flexibility can be obtained.

  The substrate may be surface treated. Specifically, the plastic substrate surface treatment includes chemical treatment, mechanical treatment, corona treatment, flame treatment, ultraviolet treatment, high frequency treatment, glow discharge treatment, plasma treatment, laser treatment, mixed acid treatment, ozone oxidation treatment, etc. A surface treatment is mentioned. Surface treatment of the substrate improves the wettability of the coating solution for forming an inorganic film with respect to the substrate, and obtains an inorganic film having a more uniform film thickness and an inorganic film having better microscopic smoothness. It is significant in that it can.

  Among the surface treatments of the plastic substrate, plasma treatment, ultraviolet irradiation treatment, corona treatment, and glow discharge treatment are preferable. In addition to being able to obtain an inorganic film having a more uniform film thickness and an inorganic film having better microscopic smoothness, these treatments cause less damage such as deformation and shrinkage of the plastic substrate in the surface treatment. Significant in terms.

  Employing atomized coating in the present invention is superior to other coating methods in that it enables formation of an inorganic film having a uniform film thickness and formation of an inorganic film having good microscopic smoothness. The inventors presume the reason as follows.

  In the present invention, the coating solution for forming an inorganic film has, as an essential component, a solvent (D) having a boiling point of 60 ° C. to 120 ° C. under atmospheric pressure and dissolving 40% by mass or more in 20 ° C. water. In the present invention, the solvent (D) having a boiling point under atmospheric pressure of 60 ° C. to 120 ° C. and dissolved in water of 20 ° C. in an amount of 40% by mass or more is compared with the case where the solvent (D) is not blended. It is thought that the surface tension of the forming coating solution is lowered to make the atomized particles in the atomized coating fine. The fine atomized particles have a surface area larger than that of the liquid film, and thus are considered to dry faster than the liquid film. In addition, the solvent (D) having a boiling point of 60 ° C. to 120 ° C. and dissolved in water of 20% by mass or more in water at 20 ° C. has a higher inorganic film formation than the case where the solvent (D) is not blended. It is thought that drying when the coating solution for coating is applied to the substrate is accelerated. By these actions, the atomized coating solution for forming an inorganic film is applied to a substrate as fine atomized particles, and after application, the atomized particles applied by drying are less fluid and less fluid. I think that it will become or no liquidity. Accordingly, the present invention is considered to enable formation of an inorganic film having a uniform film thickness and formation of an inorganic film having good microscopic smoothness. On the other hand, unlike dip coating, dip coating and spin coating do not atomize the coating solution, so the liquid film applied to the substrate is slow to dry and the liquid film flows unevenly on the substrate. . Thus, it is considered difficult to form an inorganic film having a uniform film thickness and to form an inorganic film having good microscopic smoothness by dip coating and spin coating. Therefore, the present inventors include a solvent (D) having a boiling point of 60 ° C. to 120 ° C. under atmospheric pressure and 40% by mass or more dissolved in 20 ° C. water in the coating solution for forming an inorganic film. For the first time in the present invention having both application method of atomization coating, it is possible to form an inorganic film having a uniform film thickness and to form an inorganic film having good microscopic smoothness. I guess it plays. In addition, adjusting the content of the solvent (D) whose boiling point under atmospheric pressure in the coating solution for forming an inorganic film is 60 ° C. to 120 ° C. and is dissolved by 40% by mass or more in 20 ° C. water, It is presumed that the effect of the present invention becomes more remarkable by adjusting the 50% volume average particle size of the atomized particles in the atomization coating.

  The atomization coating is not particularly limited as long as it is a method capable of atomizing and coating the inorganic film forming coating solution. For example, atomized coating that is applied by atomizing using compressed air using a two-fluid nozzle, etc., atomized coating that is applied by applying ultrasonic waves using an ultrasonic nozzle, etc., or atomized using electrostatic force Atomizing paint to be applied, atomizing paint to be applied by applying physical force such as centrifugal force and pressure, and generating a lot of atomized particles temporarily in the atomizing chamber. For example, atomized coating applied after classifying only necessary particles.

  In the atomization coating, the discharge amount of the atomization coating is not particularly limited. Preferably it is 10 g / min or less, More preferably, it is 0.1-3.0 g / min. These ranges are significant in that an inorganic film having excellent adhesion to the substrate can be formed and an inorganic film having a more uniform film thickness can be formed.

The method for setting the discharge amount of the atomized coating in the above range can be performed by a conventionally known method. For example, a method of installing an electromagnetic valve in a supply path from a pressure tank filled with the coating solution for forming an inorganic film to a nozzle, a method of reducing the nozzle diameter to about 50 to 500 μm when using a two-fluid nozzle, Examples include a method of installing a device capable of precisely controlling the discharge pressure, a method of generating a large amount of atomized particles temporarily in the atomization chamber, and a method of discharging only the necessary amount of particles from the generated particles. In the atomization coating, the 50% volume average particle diameter of the atomized particles of the atomization coating is not particularly limited. Preferably it is 20 micrometers or less, More preferably, it is 1.0-13 micrometers. These ranges are significant in that an inorganic film having better microscopic smoothness can be formed.

  The method for setting the 50% volume average particle diameter of the atomized particles of the atomized coating in the above range can be performed by a conventionally known method. Examples of the method for setting the 50% volume average particle diameter of the atomized particles of the atomized coating in the above range include a method of appropriately adjusting the nozzle diameter, the discharge amount, the atomization pressure, the air flow rate, and the like. More specifically, as a method for reducing the 50% volume average particle diameter, when a two-fluid nozzle is used for atomization coating, for example, a method for reducing the discharge amount, a method for increasing the atomization pressure, etc. Is mentioned. Specifically, for example, the discharge amount is in the range of 0.1 to 1 g / min, and the atomization pressure is in the range of 200 to 400 kPa. Moreover, when using an ultrasonic nozzle for atomization coating, the method of decreasing discharge amount, the method of raising the frequency of an ultrasonic wave, etc. are mentioned. Specifically, for example, the discharge amount is in the range of 0.1 to 10 g / min, and the frequency is in the range of 50 to 500 kHz.

  Here, in the present invention, the 50% volume average particle diameter of the atomized particles of the atomized coating is a 50% volume average particle diameter obtained by measurement using a 2600 type particle sizer (trade name, manufactured by Malvern). . The measurement is performed by measuring the atomized particles flying at the position where the substrate is placed when actually painting from the direction perpendicular to the discharge direction.

  In the atomization coating, the distance between the substrate and the nozzle is not particularly limited. The distance between the substrate and the nozzle tip is preferably 10 to 300 mm, more preferably 50 to 150 mm. By setting it as these ranges, the atomized particle can be applied to the substrate in an appropriate dry state. Thereby, an inorganic film having a more uniform film thickness can be formed. This also makes it possible to form an inorganic film with better microscopic smoothness.

  In the present invention, the inorganic film can be formed by applying the inorganic film-forming coating solution onto the substrate by atomization and leaving it at room temperature (about 20 ° C.). Therefore, in the present invention, the heating step is not essential, but the present invention preferably includes a heating step. In the heating step, while the inorganic film forming coating solution is atomized and coated on the substrate, the substrate is heated, that is, the inorganic film forming coating solution is applied to the heated substrate. This can be done by atomizing. Moreover, it can also carry out by spraying the said coating solution for inorganic film formation on a board | substrate, and heating a board | substrate after atomization coating is complete | finished.

  When performing a heating process, it is preferable to atomize-coat the said coating solution for inorganic film formation on the board | substrate currently heated. By adopting this method, the atomized particles of the coating solution for forming an inorganic film coated on the substrate can be dried more quickly. Thereby, an inorganic film having a more uniform film thickness can be formed.

  The method for heating is not particularly limited. For example, a method of placing a substrate on a hot plate and heating it can be used.

  The temperature at the time of performing a heating process is not specifically limited. Since the inorganic film forming method of the present invention can form an inorganic film by heat treatment at a low temperature, the temperature during the heating step is preferably 30 ° C. to 150 ° C., more preferably 40 ° C. to 120 ° C. Within these ranges, even when the substrate is a plastic substrate, the inorganic film can be formed on the plastic substrate without deformation or the like in the plastic substrate.

  The film thickness of the inorganic film formed by the present invention is not particularly limited. Preferably it is 50-800 nm, More preferably, it is 200-600 nm. By setting the film thickness of the formed inorganic film within these ranges, an inorganic film having excellent transparency and adhesion can be formed.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited only to these. In the examples, “parts” and “%” are “parts by mass” and “% by mass” unless otherwise specified.

Production Example 1
In a 500 ml three-necked flask, 7.0 parts by mass of stannic chloride pentahydrate (SnCl ₄ .5H ₂ O) was added and dissolved in 35 parts by mass of water. Next, aqueous ammonia was added to adjust the pH to 8 to obtain a precipitate. The precipitate was collected after filtration and washing. Subsequently, 9 times the amount of distilled water was added to the precipitate, and 25% ammonia water was added thereto to adjust the pH to 10.5, and the mixture was allowed to stand at room temperature for 24 hours to obtain a transparent aqueous solution. It was.

Production Example 2
Isopropanol was added to 100 parts by mass of the aqueous solution obtained in Production Example 1, and the coating solution No. 1 for forming an inorganic film having an isopropanol content of 100% by mass with respect to water. 1 was obtained. The obtained coating solution for inorganic film formation No. The content of stannic acid in No. 1 was 1.3% by mass in terms of SnO ₂ , and the pH was 10.5.

Production Examples 3 to 11 and Production Examples 15 to 18
To the aqueous solution obtained in Production Example 1, the solvent species shown in Table 1 was added so as to have the contents shown in the same table. 2-No. 10, no. 14-17 were obtained. Table 1 shows the stannic acid content and pH of the obtained coating solution for forming an inorganic film.

Production Example 12
In a 500 ml three-necked flask, 7.0 parts by mass of stannic chloride pentahydrate (SnCl ₄ .5H ₂ O) was added and dissolved in 35 parts by mass of water. Next, aqueous ammonia was added to adjust the pH to 8 to obtain a precipitate. The precipitate was collected after filtration and washing. Subsequently, 9 times the amount of distilled water was added to the precipitate, and ethylenediamine was added thereto to adjust the pH to 10.5, and the mixture was allowed to stand at room temperature for 24 hours to obtain a transparent aqueous solution.

  Isopropanol was added to 100 parts by mass of the obtained aqueous solution, and the coating solution No. 1 for forming an inorganic film having an isopropanol content of 100% by mass with respect to water. 11 was obtained. Table 1 shows the stannic acid content and pH of the obtained coating solution for forming an inorganic film.

Production Example 13
In a 500 ml three-necked flask, 7.0 parts by mass of stannic chloride pentahydrate (SnCl ₄ .5H ₂ O) was added and dissolved in 35 parts by mass of water. Next, aqueous ammonia was added to adjust the pH to 8 to obtain a precipitate. The precipitate was collected after filtration and washing. Subsequently, 9 times the amount of distilled water was added to the precipitate, and triethylamine was further added thereto to adjust the pH to 10.5, which was allowed to stand at room temperature for 24 hours to obtain a transparent aqueous solution.

  Isopropanol was added to 100 parts by mass of the obtained aqueous solution, and the coating solution No. 1 for forming an inorganic film having an isopropanol content of 100% by mass with respect to water. 12 was obtained. Table 1 shows the stannic acid content and pH of the obtained coating solution for forming an inorganic film.

Production Example 14
In a 500 ml three-necked flask, 7.0 parts by mass of stannic chloride pentahydrate (SnCl ₄ .5H ₂ O) was added and dissolved in 35 parts by mass of water. Next, aqueous ammonia was added to adjust the pH to 8 to obtain a precipitate. The precipitate was collected after filtration and washing. Subsequently, 9 times the amount of distilled water was added to the precipitate, and tetramethylammonium hydroxide (TMAH) was further added thereto to adjust the pH to 10.5. Obtained an aqueous solution.

  Isopropanol was added to 100 parts by mass of the obtained aqueous solution, and the coating solution No. 1 for forming an inorganic film having an isopropanol content of 100% by mass with respect to water. 13 was obtained. Table 1 shows the stannic acid content and pH of the obtained coating solution for forming an inorganic film.

(Note 1) The content in the table is the content with respect to water contained in the coating solution for forming an inorganic film, and the unit is mass%.
(Note 2) The content in the table is the content with respect to the coating solution for forming an inorganic film, and the unit is mass%.
(Note 3) Acetone: Freely mixed with water at boiling points of 56.1 ° C. and 20 ° C. under atmospheric pressure.
(Note 4) Propylene glycol monomethyl ether: Freely mixed with water at a boiling point of 121 ° C. and 20 ° C. under atmospheric pressure.
(Note 5) N, N-dimethylformamide: Freely mixed with water at a boiling point of 153 ° C. and 20 ° C. under atmospheric pressure.

Example 1
A polyethylene terephthalate substrate (100 mm × 100 mm × 0.2 mm) subjected to plasma treatment (Note 6) was heated to 50 ° C., and an inorganic film-forming coating solution No. obtained in Production Example 2 was formed on the substrate. 1 was applied by atomization coating, and an inorganic film having a film thickness of 452 nm (Note 7) was formed on the substrate to obtain a test plate. The atomizing coating uses an ultrasonic atomizing coating machine US-1 (trade name, manufactured by Rehiler, 30 ° for air conveyance) equipped with an ultrasonic nozzle having a nozzle diameter of 1 mm. The conditions were 100 mm, the discharge rate was 1.0 g / min, and the air pressure for air conveyance was 10 kPa. The 50% volume average particle diameter of the atomized particles was 10 μm. The obtained test plate was evaluated for the following items. The evaluation results are shown in Table 2.
(Note 6) The plasma treatment was carried out in argon for 3 minutes using CCR-300 (trade name, manufactured by Nikkiso Co., Ltd., plasma irradiation device).
(Note 7) A stylus type surface shape measuring device Dektak 8 (trade name, manufactured by ULVAC, Inc.) was used for measuring the film thickness. In the measurement, the measurement area was 100 mm × 100 mm, and the number of measurement points was 20. The average film thickness at each point was measured under the condition of a scan length of 3 mm for each point. The average film thickness at 20 points was calculated from the average film thickness at each point and used as the film thickness in this measurement.

Examples 2-19
On the substrate under the same conditions as in Example 1 except that the coating solution for inorganic film formation, the discharge rate, the 50% volume average particle diameter, the substrate temperature, and the film thickness of the inorganic film to be formed are shown in Table 2. A test plate was obtained by forming an inorganic film. The obtained test plate was evaluated for the following items. The evaluation results are shown in Table 2.

Example 20
On the polyethylene terephthalate substrate (100 mm × 100 mm × 0.2 mm) subjected to plasma treatment (Note 6), the coating solution No. 1 for inorganic film formation obtained in Production Example 2 was used. 1 was applied by atomization coating. The atomizing coating uses an ultrasonic atomizing coating machine US-1 equipped with an ultrasonic nozzle having a nozzle diameter of 1 mm, the distance between the substrate and the nozzle tip is 100 mm, the discharge amount is 1.0 g / min, and is used for air conveyance. The conditions were such that the air pressure was 10 kPa, and the 50% volume average particle diameter of the atomized particles was 10 μm. Subsequently, the substrate was heated to 50 ° C. and held for 10 minutes to form an inorganic film having a film thickness of 455 nm (Note 7) on the substrate to obtain a test plate. The obtained test plate was evaluated for the following items. The evaluation results are shown in Table 2.

Example 21
In Example 1, except that the thickness of the inorganic film was 94 nm (Note 7), an inorganic film was formed on the substrate under the same conditions as in Example 1 to obtain a test plate. The obtained test plate was evaluated for the following items. The evaluation results are shown in Table 2.

Comparative Examples 1-4
On the substrate under the same conditions as in Example 1 except that the coating solution for inorganic film formation, the discharge rate, the 50% volume average particle diameter, the substrate temperature, and the film thickness of the inorganic film to be formed are shown in Table 2. A test plate was obtained by forming an inorganic film. The obtained test plate was evaluated for the following items. The evaluation results are shown in Table 2.

Comparative Example 5
On the polyethylene terephthalate substrate (100 mm × 100 mm × 0.2 mm) subjected to plasma treatment (Note 6), the coating solution No. 1 for inorganic film formation obtained in Production Example 2 was used. 1 was applied by dip coating. The pulling speed during application was 50 mm / min. Subsequently, the substrate was heated to 50 ° C. and held for 10 minutes, whereby an inorganic film having a thickness of 98 nm (Note 7) was formed on the substrate to obtain a test plate. The obtained test plate was evaluated for the following items. The evaluation results are shown in Table 2.

Comparative Example 6
On the polyethylene terephthalate substrate (100 mm × 100 mm × 0.2 mm) subjected to plasma treatment (Note 6), the coating solution No. 1 for inorganic film formation obtained in Production Example 2 was used. 1 was applied by spin coating. The rotation speed at the time of application was 500 rpm. Subsequently, the substrate was heated to 50 ° C. and held for 10 minutes, whereby an inorganic film having a film thickness of 89 nm (Note 7) was formed on the substrate to obtain a test plate. The obtained test plate was evaluated for the following items. The evaluation results are shown in Table 2.

Using an adhesive microwipe MC-3000 (trade name, manufactured by MCC), a pressure of about 1 kg / cm ² was applied to the inorganic film of the test plate and rubbed back and forth for a distance of about 3 cm. The number of times until the film surface was removed and the substrate surface was exposed was measured and evaluated according to the following criteria.
A: The substrate surface is not exposed even after 50 reciprocations.
○: The substrate surface is exposed by reciprocating 25 to 49 times.
Δ: The substrate surface is exposed by 5 to 24 reciprocations.
X: The substrate surface is exposed by reciprocating 4 times or less.

Uniformity of film thickness Using a stylus type surface shape measuring device Dektak 8 (trade name, manufactured by ULVAC, Inc.), the variation in the film thickness of the inorganic film of the test plate was determined by the following method. The measurement area was 100 mm × 100 mm, the number of measurement points was 20, and the average film thickness at each point was measured under the condition of a scan length of 3 mm. Subsequently, an average film thickness at 20 points was calculated from the average film thickness at each point. The maximum value among the absolute values of the difference between the average film thickness at each point and the average film thickness at 20 points was defined as the film thickness variation. From the variation in film thickness, the uniformity of film thickness was evaluated according to the following criteria.
(Double-circle): The variation in film thickness is 10% or less.
A: The film thickness variation is larger than 10% and 20% or less.
Δ: Film thickness variation is greater than 20% and 30% or less.
X: Film thickness variation is greater than 30%.

The center line average roughness (Ra) of the inorganic film of the test plate was measured using a microscopic smooth stylus type surface shape measuring device Dektak 8 (trade name, manufactured by ULVAC, Inc.). The measurement parameters were: needle pressure: 15 mg, vertical resolution / measurement range: 10 / 655K, horizontal resolution: 32 nm, scan length: 3 mm. From the measurement results obtained, the microscopic smoothness of the film was evaluated according to the following criteria.
A: Ra is 20 nm or less.
○: Ra is larger than 20 nm and 35 nm or less.
(Triangle | delta): Ra is larger than 35 nm and is 50 nm or less.
X: Ra is larger than 50 nm.

The transmittance of the test plate thus prepared was measured with a Shimadzu spectrophotometer UV-3100PC (trade name, manufactured by Shimadzu Corporation). The measurement was performed with light having a wavelength of 550 nm. In addition, the transmittance | permeability of only the polyethylene terephthalate board | substrate used for preparation of a test board is 90.4%, The transmittance | permeability in Table 2 was computed by correct | amending this value to the transmittance | permeability 100%.

The surface resistance of the inorganic film of the test plate prepared was measured with a high resistivity meter SME-8310 (trade name, manufactured by TOA) under the conditions of a temperature of 20 ° C. and a humidity of 50% RH. In addition, what was shown by "-" in Table 2 represents that the adhesiveness was bad and could not be measured.

  In Examples 1 to 20 of the present invention, the appearance of the inorganic film immediately after coating was visually observed, and the film was in a dry state. In addition, when observed with an SEM (scanning electron microscope), the inorganic film was smooth as shown in FIG. A film was obtained, and all of adhesion, film thickness uniformity, microscopic smoothness and transparency of the film were good. On the other hand, in place of Comparative Examples 1 to 4, that is, the inorganic film forming coating solution used in the present invention, the inorganic film forming coating solution containing no solvent (D) or using a solvent other than the solvent (D). As for the inorganic film obtained by atomizing and coating, the appearance immediately after coating was observed with the naked eye in the same manner as in the examples, but in the observation by SEM, the inorganic film with many rings as shown in FIG. A film was obtained, which was inferior in terms of adhesion, microscopic smoothness of the film, and transparency as compared with the examples of the present invention.

Representative SEM images of inorganic films obtained in Examples 1-20 Representative SEM images of inorganic films obtained by Comparative Examples 1 to 4

Claims (7)

At least one compound selected from the group consisting of stannic acid (A), ammonia, tetramethylammonium hydroxide, and an amine having a boiling point of 150 ° C. or lower under atmospheric pressure and 5 mass% or more dissolved in water at 20 ° C. ( B), water (C), and an inorganic film-forming coating solution containing a solvent (D) having a boiling point of 60 ° C. to 120 ° C. and at least 40% by mass dissolved in 20 ° C. water on the substrate. An inorganic film forming method in which an inorganic film is formed by atomization coating. The content of the solvent (D) having a boiling point under atmospheric pressure of 60 ° C. to 120 ° C. and 40% by mass or more in 20 ° C. water is 40% of water contained in the inorganic film forming coating solution. The inorganic film forming method according to claim 1, wherein the content is ˜240% by mass. The inorganic film forming method according to claim 1 or 2, wherein the solvent (D) having a boiling point under atmospheric pressure of 60 ° C to 120 ° C and dissolving at least 40% by mass in water at 20 ° C is ethanol and / or isopropanol. . At least one compound (B) selected from the group consisting of ammonia, tetramethylammonium hydroxide, and an amine having a boiling point of 150 ° C. or lower under atmospheric pressure and 5 mass% or more dissolved in water at 20 ° C. is ammonia. The inorganic film forming method according to any one of claims 1 to 3. The inorganic film forming method according to any one of claims 1 to 4, wherein a discharge amount of the atomized coating is 10 g / min or less. The inorganic film forming method according to claim 1, wherein the atomized particles of the atomized coating have a 50% volume average particle diameter of 20 μm or less. The inorganic film forming method according to claim 1, wherein the substrate is heated.

Images