WO2008066077A1

WO2008066077A1 - Process for production of flakes

Info

Publication number: WO2008066077A1
Application number: PCT/JP2007/072960
Authority: WO
Inventors: Shinji Mikami; Mitsuhiro Kawazu
Original assignee: Nippon Sheet Glass Company, Limited
Priority date: 2006-11-28
Filing date: 2007-11-28
Publication date: 2008-06-05

Abstract

The invention relates to a process for the production of flakes by peeling a coating film from a substrate and aims at improving the peelability of a coating film from a substrate. The invention provides a process which comprises mixing a hydrolyzable metal compound, an acid catalyst, water and an organic solvent to prepare a sol solution containing a metal oxide precursor, applying the sol solution to a substrate to form a coating on the substrate, drying the coating to form a film, and peeling the film from the substrate to form flakes. According to the invention, the sol solution further contains both an organic compound for imparting a function to flakes and an alkali metal salt and/or an alkaline earth metal salt, when applied to a substrate.

Description

Specification

Method for producing flake body

Technical field

The present invention relates to a method for producing a flake body using a sol-gel method.

Background art

In the sol-gel method, a sol solution containing a metal oxide precursor is prepared by adding a hydrolyzable metal compound in an organic solvent containing a catalyst and water, and this metal oxide precursor is dehydrated and condensed. This is a production method in which the reaction is advanced to obtain a gelled metal oxide. As the hydrolyzable metal compound, metal alkoxide is often used.

[0003] A method for producing a flake body using a sol-gel method has been put into practical use. In this method, a sol solution containing a metal oxide precursor is applied on a flat substrate, and a coating film formed on the substrate is dried. The coating film peels off due to shrinkage caused by drying, and becomes a metal oxide flake. According to this method, it is possible to efficiently obtain a thin flake body having excellent durability. Flakes are used as fillers for plastics, corrosion-resistant linings, etc., and are sometimes blended into paints and inks.

[0004] When an organic compound is added to the sol solution in the above-described method, the metal oxide flake body has various properties such as aroma, deodorant, deodorant, bactericidal, water-repellent, conductive, and heat-sensitive. Functions can be added.

[0005] In JP-A-4 292430, a solution containing an organometallic compound and an organic dye is applied onto a substrate to form a coating film, and the coating film is peeled off from the substrate to contain an organic dye. A method for obtaining a flake body is disclosed.

However, especially when a hydrophobic organic compound such as an organic dye is added to the sol solution, the organic compound may aggregate or precipitate in the sol solution. Although this phenomenon does not occur during preparation of the solution, it may occur during drying of the coating film. The degree of occurrence of the aggregation or precipitation of the organic compound varies depending on the solvent contained in the sol solution and the affinity between the metal oxide precursor and the organic compound. For example, the affinity between the organic compound and the metal oxide precursor is low! / And evenly dispersed in the sol solution! / In the process of volatilization of the solvent, organic compounds aggregate or precipitate. If the organic compound aggregates or precipitates and the distribution of the organic compound in the flakes becomes non-uniform, the function of the organic compound cannot be effectively exhibited. If a dispersant is used, aggregation or precipitation of organic compounds can be suppressed. However, it is desirable to avoid the use of dispersants because they may remain in the flake body and impair its performance.

[0007] Japanese Patent Application Laid-Open No. 2006-150300 discloses that an organic compound is prepared by adjusting the amount of water added to a sol solution so that it is sufficient but sufficient for the hydrolysis reaction of a metal compound. It is disclosed to prepare a uniformly dispersed sol solution! If a flake body is produced using this sol solution, a flake body in which an organic compound is uniformly dispersed can be obtained without using a dispersant.

However, when a sol solution having a small water content is used, the dried coating film is firmly attached to the substrate. For this reason, it becomes difficult for the coating film to be peeled off. Such a tendency becomes more prominent as the coating film thickness becomes smaller. For this reason, it is necessary to increase the thickness of the coating film, and the thickness of the obtained flake body also increases. However, if a flake body having a large thickness is added to a paint, ink or the like, problems such as concealing property, sedimentation property, coating force, and protrusion of the film easily occur. Disclosure of the invention

[0009] An object of the present invention is to provide a method for producing a flake body using a sol-gel method, in which a coating film is easily peeled from a substrate!

[0010] The present inventors have found that the releasability of a coating film formed on a substrate can be improved by adding an alkali metal salt and / or an alkaline earth metal salt to a sol solution.

In the present invention, at least a hydrolyzable metal compound, an acid catalyst, water, and an organic solvent are mixed to prepare a sol solution containing a metal oxide precursor, and this sol solution is applied onto a substrate. Then, a coating film is formed on the substrate, the coating film is dried, and the coating film is peeled off from the substrate to obtain a flake body, in which the sol solution is coated on the substrate. When provided, a method for producing a flake body is provided, further comprising an organic compound and at least one salt selected from the group consisting of alkali metal salts and alkaline earth metal salts.

[0012] According to the present invention, the amount of water added to the sol solution is increased by adding the salt. Even if there are few, the flake body excellent in peelability can be manufactured easily and efficiently. The production method of the present invention is particularly suitable for providing a thin flake body in which an organic compound is uniformly dispersed.

FIG. 1 is a block diagram for explaining an example of the method of the present invention.

FIG. 2 is a diagram showing a result of observation of an example of a flake body obtained by the method of the present invention with a scanning electron microscope.

BEST MODE FOR CARRYING OUT THE INVENTION

[0014] The method for producing a flake body according to the present invention can be carried out according to the process shown in FIG. Hereinafter, one embodiment of the present invention will be described in accordance with the steps shown in FIG.

[0015] [Preparation of sol solution]

In the method for producing a flake body of the present invention, first, at least a hydrolyzable metal compound, an acid catalyst, water, and an organic solvent are mixed, and a metal oxide precursor generated by hydrolysis of the metal compound is included. A sol solution is prepared.

[0016] The type of the organic solvent is not limited, but an organic solvent having high solubility of the metal compound to be used is suitable. As the organic solvent, alcohols, glycols, cellosonolev (ethylene glycol monoether), and the like can be used. As alcohols, lower alcohols such as methanol, ethanol and isopropanol are preferred. As glycols, ethylene glycol, propylene glycol and the like are preferable. As the mouth solvs, cetyl sorb butyl, butyl mouth solv and the like are preferable. Note that organic solvents with low volatility such as dariserine and hexylene dallicol have the advantage that the decrease in organic solvent due to volatilization can be suppressed.

[0017] The hydrolyzable metal compound has a functional group as a reaction point to water in the molecule, and can form a metal oxide precursor by hydrolysis reaction. Examples of hydrolyzable metal compounds include metal alkoxides, metal carboxylates, nitrates, chlorides and oxychlorides. Among these, the metal alkoxide is easy to control the reaction and easily forms a three-dimensional network structure of the metal oxide at a low temperature. Composing metal compounds The type of metal atom is not limited, but may be silicon, titanium, aluminum, zirconium or the like.

[0018] The metal alkoxide is represented by the general formula: MR (OR '). Here, M is a metal atom, R is an organo group (strictly, an organic group excluding an alkoxyl group), and OR ′ is an alkoxyl group. N is a natural number corresponding to the oxidation number of the metal atom, and m is an integer in the range of 0≤m <n. Examples of R include an alkyl group, a phenyl group, a acyl group, a methacryloxy group, and an epoxy group. Examples of R ′ include an alkyl group, a phenyl group, an acetyl group, and a (poly) oxyalkylene group. Among them, the number of carbon atoms such as a methyl group, an ethyl group, a propyl group, and an isopropyl group is 1 to An alkyl group of 5 is preferred.

[0019] Examples of the metal alkoxide (silicon alkoxide) in which the metal atom is silicon include tetraalkoxysilane having four reaction points to water, such as tetramethoxysilane, tetraethoxysilane, and tetrapropoxysilane. (Alkoxysilane A; m = 0) can be used. The use of alkoxysilane A is preferable from the viewpoint of improving the strength of the flake body and the raw material cost. On the other hand, as the silicon alkoxide, an alkoxysilane having an organo group (alkoxysilane B; m> 0; preferably m = 1 or 2) such as methyltrimethoxysilane or phenyltrimethoxysilane can be used. The use of alkoxysilane B is preferable from the viewpoint of improving the stability of the sol solution and the dispersibility of the organic compound. In order to obtain a flake body having a high strength and a low cost while uniformly dispersing the organic compound, alkoxysilane A and alkoxysilane B may be used in combination.

[0020] Titanium alkoxides such as tetraisopropoxytitanium are highly reactive and thus gelate immediately after hydrolysis. When such highly reactive metal alkoxide is used, it is desirable to add a chelating agent to an organic solvent in advance to stabilize the metal oxide precursor obtained by the hydrolysis reaction. As the chelating agent, 0-diketones such as acetyl acetone and 0-keto esters such as acetyl acetoacetate can be preferably used. In addition, you may use the organic solvent which has the effect as a chelating agent together.

[0021] The metal element contained in the metal compound is not limited to one type, and may be a plurality of types as required. For example, a metal oxide flake body having a desired refractive index can be produced by mixing metal compounds having different metal elements. In this case, multiple A sol solution may be prepared by blending these metal compounds, or separately prepared sol solutions may be mixed.

[0022] The acid catalyst accelerates the hydrolysis reaction of the metal compound and suppresses the gelation of the resulting metal oxide precursor. Protonic acid is preferably used as the acid catalyst. Examples of the acid catalyst include nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, citrate, acetic acid, trifluoroacetic acid, trichlorodiacetic acid, p-toluenesulfonic acid, and the like.

In the sol-gel method, water is added for the hydrolysis reaction of the metal compound. The amount of water added is preferably 0.5 equivalents or more and 2 equivalents or less based on the number of reaction points of the metal compound with water. If the amount of water added is less than 0.5 equivalent, the hydrolysis reaction of the metal compound may not proceed sufficiently. If the hydrolysis reaction does not proceed sufficiently, the strength of the flake body will be reduced. If this reaction does not proceed sufficiently, the amount of water in the sol solution decreases, and it may be difficult to peel off the flakes from the substrate strength. On the other hand, when the amount of water added exceeds 2 equivalents, it becomes difficult to uniformly disperse the organic compound in the sol solution. The present invention has a high utility value as a supplement to the decrease in the peelability of the coating film that occurs when the amount of water added is limited to the above level. Yes.

[0024] The amount of water contained in the sol solution varies due to hydrolysis of the metal oxide and subsequent dehydration condensation. The amount of water also varies when an aqueous solution is used as an additive to the sol-gel solution. In order to maintain the dispersibility of the organic compound, it is desirable that the water content of the sol solution when applied to the substrate is within a predetermined range. Specifically, the water content of the final sol solution before application (the water content contained in the sol solution applied on the substrate) is preferably 10% by mass or less.

[0025] [Preparation of film forming solution]

Next, a film forming solution is prepared from the sol solution obtained above. In the embodiment described here, at least an organic compound and an alkali metal salt and / or an alkaline earth metal salt are added to the sol solution to prepare a film forming solution. The film-forming solution is also a sol solution containing a metal oxide precursor, but here the term “film-forming solution” is used to distinguish these two solutions. [0026] The organic compound and the salt may be added in advance to the solution before hydrolysis of the metal compound. In this case, the sol solution obtained by hydrolyzing the metal compound may be directly applied to the substrate. However, organic compounds should be added to the sol solution in consideration of the fact that there are many substances that become weak to light and heat when dissolved in a solvent and that the stability of the solution may be reduced by the addition of organic compounds. From the viewpoint of solution stability, it is also preferable to prepare the sol solution and add it to this sol solution!

[0027] The organic compound is added to the flake body in order to impart various functions such as fragrance, deodorizing property, deodorizing property, bactericidal property, water repellency, conductivity, and heat sensitivity. Examples of the organic compound include, but are not limited to, compounds such as phthalocyanines, porphyrins, polycyclic aromatics (pyrene, etc.). Organic compounds for imparting the functions exemplified above are often hydrophobic. Although it is not always easy to disperse the hydrophobic organic compound uniformly in the flake body, it can be uniformly dispersed if the amount of water is appropriately controlled as described above. Hydrophobic organic compounds often contain a ring structure of carbon atoms typified by a benzene ring.

[0028] As the salt, at least one salt selected from the group consisting of alkali metal salts and alkaline earth metal salts can be used. The at least one salt preferably includes an alkali metal salt. The alkali metal salt preferably includes sodium or potassium. Examples of the alkali metal salt include sodium acetate, potassium acetate, sodium sulfate, and sodium nitrate. Examples of the alkaline earth metal salt include magnesium acetate, calcium acetate, magnesium nitrate, and calcium nitrate. The at least one salt may include acetate, sulfate or nitrate.

[0029] The reason why the peelability of the coating film is improved by the addition of salt is not always clear at this stage. However, the addition of salt promotes the reaction from the sol to the gel in the coating film, and the increase in stress in the coating film is thought to contribute to the improvement of peelability. If the stress in the film increases, the film tends to crack as the film dries. In the process of gelling the sol, the alkali metal or alkaline earth metal may be separated from the sol and unevenly distributed between the substrate and the coating film. Since the adhesion between the metal and the substrate is low, the film is easy to peel off if the metal is unevenly distributed at the interface with the film. [0030] The amount of the salt added is preferably 0.1 equivalents or more and 1.5 equivalents or less based on the acid catalyst. If the amount of salt added is less than 0.1 equivalent, the effect of the salt may not be sufficiently obtained, and as a result, the flake peelability may not be improved. On the other hand, if the amount of salt added is too large relative to the acid catalyst, the sol solution may move to the alkaline side and the sol solution may be easily gelled. If gelation of the sol solution is to be surely prevented, the amount of salt added should be in the range of 0.;! To 1 equivalent to the acid catalyst. On the other hand, when the peelability should be emphasized, the amount of salt added may be in the range of !! to 1.5 equivalents with respect to the acid catalyst. In general, sol solutions tend to gel easily as their liquidity approaches from alkaline to alkaline.

[0031] The salt may be added directly to the sol solution. However, in order to mix the salt more uniformly, it is preferable to prepare a solution in which the salt is dissolved in an appropriate solvent in advance and then mix this solution with the sol solution. A preferred solvent for this solution is water. However, when water is used as the solvent, the water content of the sol solution is preferably limited to 10% by mass or less in order not to lower the dispersibility of the organic compound. For this purpose, the salt may be dissolved in an organic solvent containing a small amount of water. As the salt, an organic acid salt such as sodium acetate or sodium quenate may be used. If an alkali metal salt of an organic acid and / or an alkaline earth metal salt is used, a solution containing only an organic solvent as a solvent can be easily prepared. This organic solvent may be the same as or different from the organic solvent contained in the sol solution.

[0032] As described above, in the present invention, it is preferable to add a solution containing an alkali metal salt and / or an alkaline earth metal salt to the sol solution before applying the sol solution onto the substrate. This solution may contain water and an organic solvent as a solvent.

[0033] An organic compound can also be added to the sol solution before coating on the substrate. The organic compound may be added as the compound itself or in the form of a dispersion or solution.

[0034] In the production method of the present invention, the sol solution may contain other components such as hydroxide, halide, and nitride.

[0035] [Application of film-forming solution]

Next, a coating film is formed by applying the film forming solution obtained above onto the surface of the substrate. To do.

[0036] Glass, metal, semiconductor, ceramics, resin, and the like, which are not particularly limited, can be used as the base material. However, when using a resin, a material having a temperature higher than the boiling point of the organic solvent contained in the film-forming solution and having a heat resistant temperature should be selected. A stainless steel plate is an example of the substrate that is excellent in the flake peelability. Further, in order to obtain a flat flake having a uniform thickness, the surface of the substrate on which the coating film is formed is preferably smooth.

[0037] The method of applying the film-forming solution to the substrate may be performed using a known technique! Examples of the coating method include spin coating, roll coating, spraying, dating, curtain coating, flow coating, and various printing methods (screen printing, flexographic printing, ink jet method, etc.). In order to make the coating film thickness uniform, a leveling time may be provided as needed between application and drying.

[0038] [Drying and peeling of coated film]

Subsequently, the coating film formed on the surface of the substrate is dried. This drying may be carried out by natural drying, but in order to accelerate the dehydration condensation reaction of the metal oxide precursor and facilitate the volatilization of the organic solvent and water, it is possible to carry out the drying by heating with heating of the substrate. It is preferable to do it. The heating temperature should be set lower than the heat resistance temperature of the organic compound contained in the substrate and the coating film. The heating temperature is preferably set higher than the boiling point of the organic solvent contained in the coating film. Examples of preferable heating temperature include 80 ° C to 250 ° C.

[0039] In the process of drying the coating film, the dehydration condensation reaction of the metal oxide precursor proceeds in the coating film, and a metal oxide network structure is formed. As drying progresses further, the coating film contracts, tensile stress is generated, and cracks occur in the coating film. When the crack force S is extended, the fine pieces of the coating film are spontaneously peeled off from the substrate, and a flake body is obtained. If the flake body does not peel off naturally, it may be peeled off by applying external force.

[0040] The peeled flake body may be collected by suction, or may be collected by scraping with a brush, a scraper or the like. The flake body is recovered by blowing compressed air or the like. Alternatively, it may be immersed in a solution and settled in the solution to be collected.

[0041] According to the present invention, a flake body in which the organic compound is uniformly dispersed in the metal oxide and the thickness is thin can be obtained. Thin flake bodies can provide a variety of functions to products that add flake bodies that do not cause problems such as hiding, settling, and sticking out of the coating. FIG. 2 shows the result of observation of an example of the flake body obtained by the production method of the present invention with a scanning electron microscope. The magnification is 1000 times.

[0042] Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.

[0043] (Example 1)

68. lg of isopronol, 48.6 g of tetramethoxylane (Tokyo Chemical Industry Co., Ltd.), and 4.65 g of methyltrimethoxysilane (Shin-Etsu Chemical Co., Ltd.) are mixed. To this mixed solution, 18.4 g of a 0.1 mol / L nitric acid aqueous solution was dropped, and the mixture was stirred at 50 ° C. for 24 hours to prepare a sol solution. The amount of water added is a ratio of 0.76 equivalent to the number of reaction points of alkoxysilane with water.

[0044] Separately from the above sol solution, 78 mg of sodium acetate, 40 g of isopropanol, and 10 g of ion-exchanged water were mixed to prepare a sodium acetate solution.

[0045] To 10 g of the sol solution, 38 mg of pyrene and 5 g of a sodium acetate solution were mixed to prepare a film forming solution. To this film forming solution, sodium acetate was added at a ratio of 0.7 equivalent to the content of nitric acid as an acid catalyst.

[0046] The water content of the film-forming solution was measured by the Karl Fischer method and found to be 9% by mass. The above-mentioned measurement by the Karl Fischer method is performed by coulometric titration using the “Micro moisture analyzer CA-05” manufactured by Mitsubishi Kasei Kogyo Co., Ltd. and “Aquamicron AX” manufactured by Mitsubishi Chemical Co., Ltd. Implemented by law. The coulometric titration method is a method that uses a detection electrode to measure the number of electrons (current) emitted when iodide ions generated by the reaction of water and an analytical solution return to iodine.

[0047] The film-forming solution was dropped onto a stainless steel (SUS304) substrate having a size of 100 X 100 mm, and a coating film was formed by a spin coating method. Within 30 seconds after coating, the stainless steel substrate with the coating film was placed in a drying furnace heated to 250 ° C. and heated for 60 seconds. Subsequently, the stainless steel substrate was taken out of the drying furnace, and flake bodies naturally separated from the substrate surface were collected. [0048] Here, coating and drying operations were repeated while gradually increasing the rotation speed of the spin coater, and the thinnest flake body that could be naturally peeled was obtained.

[0049] The thickness of the obtained flake body was measured using a scanning electron microscope (manufactured by Keyence, VE-7800). Here, the thickness of 10 20 flake bodies selected arbitrarily was measured, and the average value was defined as the thickness of the flake bodies (the same applies hereinafter). The thickness of the flake body of Example 1 was 0 · 64〃111.

[0050] (Comparative Example 1)

In the preparation of the sodium acetate solution, the same solution as in Example 1 was used except that a mixed solution of isopropanol and water prepared by adding the same amount of water instead of sodium acetate was used instead of the sodium acetate solution. The thinnest flake body which can be peeled was obtained. The thickness of this flake body was 1.31 m, which was larger than the thickness of the flake body of Example 1.

[0051] (Example 2)

The thinnest flake body that can be naturally peeled was obtained in the same manner as in Example 1, except that 18.4 g of 0.2 mol / L aqueous citrate solution was used instead of nitric acid as the acid catalyst. The flake body had a thickness of 0.65 m.

[0052] (Comparative Example 2)

In the preparation of the sodium acetate solution, natural solution was obtained in the same manner as in Example 2 except that a mixed solution of isopropanol and water prepared by adding the same amount of water instead of sodium acetate was used instead of the sodium acetate solution. The thinnest flake body which can be peeled was obtained. The thickness of the flake body was 2.02 m, which was larger than the thickness of the flake body of Example 2.

[0053] (Example 3)

The thinnest flake body that can be peeled naturally was obtained in the same manner as in Example 2 except that 156 mg of sodium acetate was used instead of 78 mg of sodium acetate. The average thickness of this flake body was 0 · 59 m.

[Example 4]

Except that 312mg sodium acetate was used instead of 78mg sodium acetate. In the same manner as in Example 2, the thinnest flake body that can be naturally peeled was obtained. The average thickness of the flakes was 0 · 53 m.

[Example 5]

The thinnest flake body that can be naturally peeled was obtained in the same manner as in Example 2 except that 128 mg of sodium sulfate was used instead of 78 mg of sodium acetate. The average thickness of this flake body was 0 · 56 m.

[Example 6]

The thinnest flake body that can be peeled naturally was obtained in the same manner as in Example 2 except that 256 mg of magnesium nitrate hexahydrate was used instead of 78 mg of sodium acetate. The average thickness of this flake body was 0 · 69 m.

[0057] (Example 7)

The thinnest flake body that can be naturally peeled was obtained in the same manner as in Example 2 except that 214 mg of magnesium acetate tetrahydrate was used instead of 78 mg of sodium acetate. The average thickness of this flake body was 1 · 21 111.

[Example 8]

The thinnest flake body that can be naturally peeled was obtained in the same manner as in Example 2 except that 255 mg of barium acetate was used instead of 78 mg of sodium acetate. The average thickness of this flake body was 1 · 14 m.

[Example 9]

The thinnest flake body that can be peeled naturally was obtained in the same manner as in Example 2 except that 38 mg of Disperse Redl was added instead of pyrene. The average thickness of this flake body was 0.56 m.

[0060] (Comparative Example 3)

In the preparation of the sodium acetate solution, a natural solution was added in the same manner as in Example 9 except that a mixed solution of isopropanol and water prepared by adding the same amount of water instead of sodium acetate was used instead of the sodium acetate solution. The thinnest flake body which can be peeled was obtained. The thickness of this flake body was 1.22 m, which was larger than the thickness of the flake body of Example 9. [Example 10]

The thinnest flake body that can be naturally peeled was obtained in the same manner as in Example 2 except that 38 mg of azobenzene was added instead of pyrene. The average thickness of this flake body was 0.36 m.

[0062] (Comparative Example 4)

A natural solution was prepared in the same manner as in Example 10 except that a mixed solution of isopropanol and water prepared by adding the same amount of water instead of sodium acetate in the preparation of the sodium acetate solution was used instead of the sodium acetate solution. The thinnest flake body which can be peeled was obtained. The thickness of this flake body was 0.6 m, which was larger than the thickness of the flake body of Example 10.

[0063] The results of each Example and Comparative Example are shown together in Table 1 together with the added amount of salt, the added amount of water and the like.

[0064] [Table 1]

* NaAct: Sodium acetate, NaS lf _: Sodium sulfate, MgNtr: Mac nitrate Nesium hexahydrate,

MgAct: Magnesium acetate tetrahydrate, BaAct: Ha'lium acetate, DR: D i sperse Red 1 [0065] From the results of Examples and Comparative Examples, it can be seen that when a salt is added to the sol solution, no salt is added! /, A thinner flake body can be obtained than in the case. In the examples and comparative examples presented here, the force S in which the amount of water added was in the range of 0.7 to 0.8 equivalents, and 0.5 to 2 In the range of equivalents, the tendency that the minimum film thickness tends to be thinned by the addition of salt has been confirmed, as in the above examples.

[0066] Generally, if the coating film is thin, the volume shrinkage of the film during drying is small, and therefore the flake body is difficult to peel from the substrate. In addition, if the amount of water in the sol solution applied onto the substrate is limited in order to uniformly disperse the organic compound, the volume shrinkage of the film during drying is also reduced, and the flaking property of the flake body decreases. The production method of the present invention has a high value and utility value as a supplement to the decrease in the peelability of the coating film from the substrate.

Claims

The scope of the claims

[1] Mix at least a hydrolyzable metal compound, an acid catalyst, water, and an organic solvent.

Preparing a sol solution containing a metal oxide precursor;

Applying the sol solution on a substrate to form a coating film on the substrate;

A method for producing a flake body, wherein the coating film is dried, and the coating film is peeled from the substrate to obtain a flake body,

When the sol solution is applied onto the substrate, the flake body further comprises an organic compound and at least one salt selected from the group consisting of an alkali metal salt and an alkaline earth metal salt. Method.

2. The method for producing a flake body according to claim 1, wherein the at least one salt includes an alkali metal salt, and the alkali metal salt includes sodium or potassium.

[3] The method for producing a flake body according to claim 1, comprising at least one salt strength acetate, sulfate or nitrate.

[4] The method for producing a flake body according to claim 1, wherein the amount of the at least one salt is 0.1 equivalent or more and 1.5 equivalent or less with respect to the acid catalyst.

[5] The method for producing a flake body according to claim 1, wherein the amount of water added is 0.5 equivalents or more and 2 equivalents or less with respect to the number of reaction points of the metal compound with water.

[6] The amount of water contained in the sol solution when coated on the substrate is 10% by mass or less

The method for producing a flake body according to claim 1.

[7] The method for producing a flake body according to claim 1, wherein the organic compound is a hydrophobic organic compound.

[8] The method for producing a flake body according to claim 1, wherein the organic compound contains a ring structure of carbon atoms.

[9] The method for producing a flake body according to claim 8, wherein the ring structure of the carbon atom includes a benzene ring.

[10] Before applying the sol solution onto the substrate,

The method for producing a flake body according to claim 1, wherein a solution containing the at least one salt is added to the sol solution.

[11] The method for producing a flake body according to claim 10, wherein the solution containing at least one salt contains water and an organic solvent as a solvent.

[12] Before applying the sol solution onto the substrate,

The method for producing a flake body according to claim 1, wherein the organic compound is added to the sol solution.