JP3052230B2 - Method of forming inorganic paint film - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for forming an inorganic paint film.

[0002]

2. Description of the Related Art In an antibacterial organic paint containing an antibacterial agent in an organic resin, the resin deteriorates when used for a long period of time. Especially when used outdoors, dirt adheres to the surface,
There was a disadvantage that the antimicrobial performance of the coating film was apt to decrease due to the deterioration due to ultraviolet rays. Therefore, inorganic coatings containing an antibacterial agent in a silicate-based, phosphate-based, zirconium-based inorganic composition are known, but the above-mentioned inorganic coatings have better durability than organic coatings. Since it is necessary to bake at a high temperature of 200 ° C. or more, the usable range is limited, and it is not suitable for directly applying to building materials and plastics. In addition, when used for a long period of time, silicate-based inorganic coatings have a disadvantage that alkali elutes to the surface and the efflorescence tends to occur. JP-A-62-57470 discloses an inorganic coating containing a metal alkoxide. Although this inorganic coating cures at 200 ° C. or lower, the coating has no flexibility and easily cracks. There was a problem. recent years,
Due to the necessity of using paints for a wide variety of materials, antibacterial performance is maintained even after long-term use, and there is no crack.
There has been a demand for a paint that can be baked at a temperature of 0 ° C. or less.

[0003]

Accordingly, the present inventors have proposed, in Japanese Patent Application No. 6-205835, an antibacterial inorganic paint containing a photocatalyst which is a component having a photocatalytic function as an antibacterial agent. However, when a photocatalyst is supported on a substrate,
There are difficulties in the restriction and adhesion of the base material, and when a photocatalyst is formed into a coating film using a paint, in the case of an organic paint, the coating film itself is deteriorated due to the oxidizing action of the photocatalyst, and the performance is easily reduced,
When an inorganic paint is used, the photocatalyst tends to settle in the inorganic paint, and the performance of the photocatalyst tends to be hardly exhibited.

The present invention has been made in view of the above-mentioned facts, and has as its object to carry a photocatalyst on the surface,
An object of the present invention is to provide a method for forming an inorganic coating film having high photocatalytic performance.

[0005]

According to a first aspect of the present invention, there is provided a method for forming an inorganic coating film, comprising the following compositions (A), (B) and (C) as raw materials, and mixing these raw materials: Hydrolysis of this mixture, and, after applying a first inorganic coating having a weight average molecular weight of 900 or more in terms of polystyrene adjusted by performing a polycondensation reaction on a substrate, applying a photocatalyst dispersed in a solvent, On these, the following composition (A),
Using (B) and (C) as raw materials, mixing these raw materials,
This mixture is subjected to hydrolysis and polycondensation reaction, and a second inorganic paint having a weight-average molecular weight of 900 or more in terms of polystyrene is applied to form a photocatalyst-containing coating film. (A) a silicon compound represented by the following general formula and / or colloidal silica 20 to 200 parts by _{^{weight, Si (OR 1) 4 ------}} (B) silicon represented by the following general formula 100 compounds
Parts by weight, R ² Si (OR ¹ ) _3- (C) A silicon compound represented by the following general formula,
0 parts by ^{_{weight, R 2 2 Si (OR 1}} ) 2 ------ [In the general formula ~ general formula, R ^1, R ² represents a monovalent hydrocarbon group. The method for forming an inorganic paint film according to claim 2 of the present invention is the method for forming an inorganic paint film according to claim 1, wherein the second inorganic paint has a reduced concentration of the first inorganic paint. Characterized in that:

According to a third aspect of the present invention, there is provided a method for forming an inorganic coating film according to the first or second aspect, wherein the solvent has a surfactant and / or a boiling point of 100. It is characterized by containing a solvent (drying control agent) of up to 250 ° C.

According to a fourth aspect of the present invention, there is provided a method for forming an inorganic coating film according to any one of the first to third aspects, wherein the drying control agent comprises formamide, dimethylformamide, It is at least one selected from the group consisting of acetonitrile, dioxane and normal heptane.

Hereinafter, the present invention will be described in detail.

The method for forming an inorganic coating film according to the present invention comprises:
This is a method in which a photocatalyst dispersed in a solvent is applied after applying the first inorganic coating to a substrate, and a second inorganic coating is applied thereon to form a photocatalyst-containing coating film. The solvent may be any of methanol, acetone, ethanol, propanol, isopropyl alcohol and the like. However, considering the exchange reaction of the hydrocarbon group (R) of the alkoxide in the inorganic paint to be used, it is desirable to match with R in the inorganic paint.

The silicon compound as a raw material of the first and second inorganic coatings is represented by the following general formula.

[0011] In _{^{R 2 n Si (OR 1)}} 4-n ------ [In the general formula, n an integer of 0~3, R ^1, R ² represents a monovalent hydrocarbon group. R ¹ in the above general formula,
R ² is not limited as long as it represents a monovalent hydrocarbon group,
R ² represents a substituted or unsubstituted hydrocarbon group having 1 to 8 carbon atoms, for example, a methyl group, an ethyl group, a propyl group,
Butyl group, pentyl group, hexyl group, heptyl group, alkyl group such as octyl group, cyclopentyl group, cycloalkyl group such as cyclohexyl group, 2-phenylethyl group,
Aralkyl groups such as 3-phenylpropyl group, aryl groups such as phenyl group and tolyl group, anenyl groups such as vinyl group and allyl group, chloromethyl group, γ-chloropropyl group, and 3,3,3-trifluoropropyl group Such as a halogen-substituted hydrocarbon group, and a γ-methacryloxypropyl group, γ-
And substituted hydrocarbon groups such as a glycidoxypropyl group, a 3,4-epoxycyclohexylethyl group, and a γ-mercaptopropyl group. Above all, ease of synthesis, or
An alkyl group having 1 to 4 carbon atoms and a phenyl group are preferable in terms of availability.

In the above general formula, R ¹ has ¹ to 4 carbon atoms.
Those having an alkyl group as a main raw material are used. In particular,
Examples of the tetraalkoxysilane with n = 0 include tetramethoxysilane, tetraethoxysilane, and the like.
Examples of the organotrialkoxysilane 1 include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and 3,3,3-trifluoropropyltrimethoxysilane. Is done. further,
Examples of the diorganodialkoxysilane of n = 2 include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and methylphenyldimethoxysilane.
Examples of the triorganoalkoxysilane of = 3 include trimethylmethoxysilane, trimethylethoxysilane, trimethylisopropoxysilane, and dimethylisobutylmethoxysilane.

R ¹ and R ^{2 in the} above general formulas
May be the same hydrocarbon group or different. The production of the inorganic paint is, for example, the above general formula,
It is prepared by diluting a silicon compound represented by the above general formula or the above general formula with a solvent, adding water or a catalyst as a curing agent, and performing hydrolysis and polycondensation reactions. The weight average molecular weight (Mw) of these silicon compounds is calculated in terms of polystyrene. In this preparation, the weight average molecular weight (Mw) of the inorganic coating is adjusted to 900 or more in terms of polystyrene. When the weight average molecular weight (Mw) is less than 900 in terms of polystyrene, the curing shrinkage becomes large during the polycondensation reaction, and cracks are easily generated in the baked inorganic paint film.

The above-mentioned inorganic paint can be used in combination with the silicon compound represented by the above general formula, or can contain colloidal silica instead. The colloidal silica is water-dispersible colloidal silica dispersed in water, or
Organic solvent-dispersible colloidal silica dispersed in a non-aqueous organic solvent such as alcohol. The colloidal silica contains 20 to 50% by weight of silica as a solid content. In preparing the inorganic coating, the water-dispersible colloidal silica can use water existing as a component other than the solid content as a curing agent. Further, colloidal silica dispersible in an organic solvent can be easily prepared by replacing the organic solvent with water. Examples of the organic solvent in which the colloidal silica is dispersed include lower aliphatic alcohols such as methanol, ethanol, isopropanol, n-butanol and isobutanol, ethylene glycol, ethylene glycol monobutyl ether, and ethylene glycol monoethyl ether acetate. And derivatives of diethylene glycol such as diethylene glycol and diethylene glycol monobutyl ether, and diacetone alcohol. One or more of these are used. Further, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketoxime and the like can be used in combination with a hydrophilic organic solvent. The amount of the colloidal silica is a weight including the dispersion medium.

Water is generally used as a curing agent when preparing an inorganic paint, and the amount of water is preferably 45% or less, more preferably 25% or less in the inorganic paint.

The organic solvent used for preparing the inorganic coating includes, for example, lower aliphatic alcohols such as methanol, ethanol, isopropanol, n-butanol and isobutanol, ethylene glycol, ethylene glycol monobutyl ether, and ethylene glycol monoacetate. Ethylene glycol derivatives such as ethyl ether; diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether; and diacetone alcohol.
More than one species is used. Further, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketoxime and the like can be used in combination with a hydrophilic organic solvent.

In the preparation of the above inorganic coating, the p of the inorganic coating is
It is desirable for H to be 3.8-6. When the pH is within this range, the preservability of the inorganic coating is good, and when the pH is outside the pH range, the application period from the preparation period is limited. The method of adjusting the pH is not limited. For example, when the pH is less than 3.8 when the materials are mixed, the pH may be adjusted by adding a basic reagent such as ammonia, and the pH exceeds 6. In this case, it may be adjusted by adding an acidic reagent such as hydrochloric acid.
In addition, depending on the pH, when the reaction progresses slowly in a state where the molecular weight is small, heating may be used to accelerate the reaction,
After the reaction is advanced by lowering the pH with an acidic reagent, a basic reagent may be added to adjust the pH to a predetermined value.

Examples of the photocatalyst include titanium oxide, zinc oxide, tin oxide, zirconium oxide, tungsten oxide, chromium oxide, molybdenum oxide, iron oxide, nickel oxide, ruthenium oxide, cobalt oxide, copper oxide and manganese oxide. At least one selected from the group consisting of: The above photocatalyst is added to the inorganic paint as long as the functional weather resistance of the inorganic paint is not impaired. A metal may be supported on these photocatalysts. As this metal, for example,
At least one selected from the group consisting of gold, silver, copper, iron, zinc, nickel, cobalt, platinum, ruthenium, palladium, and rhodium is used. By carrying these metals, the charge separation of the photocatalyst is promoted, and the photocatalysis is exhibited. In other words, it has an oxidizing performance in the presence of light, and this oxidizing performance provides effects such as deodorization and antibacterial effects. further,
A clay crosslinked body having a photocatalyst supported between layers may be used. By introducing these photocatalysts between the layers, the oxide is supported on the fine particles, and the photocatalytic performance is improved.

In the inorganic coating film, a second coating material is further applied on the photocatalyst. That is, since the second inorganic paint is applied thinly, the photocatalyst is fixed to the inorganic paint film, so that the photocatalyst does not fall off, and the surface properties of the inorganic paint film are improved. It is more preferable that the concentration of the first inorganic coating used in the present invention is reduced to form a second inorganic coating to form a thinner coating film.

By etching the inorganic coating film with an acid or an alkali, only the inorganic coating is dissolved, and the catalytic effect of the photocatalyst is improved. The acid or alkali need not dissolve the photocatalyst or react with the photocatalyst, and examples thereof include sodium hydroxide of about 0.1 to 1% by weight.

Surfactants and / or having a boiling point of 100 to 25
By adding a drying control agent (DCCA), which is a solvent at 0 ° C., to the solvent, the dispersibility of the photocatalyst is increased, and a porous coating film is obtained in the drying step. That is, by drying the inorganic paint film at, for example, 100 ° C. or more, additives such as a surfactant and a drying control agent are decomposed, and a porous inorganic paint film is obtained. Examples of the drying control agent include at least one selected from the group consisting of formamide, dimethylformamide, acetonitrile, dioxane, and normal heptane. Examples of the surfactant include amines such as octadecylamine salt, methyls such as octadecyltrimethylammonium salt and dodecyltrimethylammonium salt, and dodecylbenzenesulfonate. These drying control agents and / or surfactants are uniformly mixed in a solvent such as methanol. Additives such as the drying control agent and the surfactant have good affinity with the inorganic paint, can be highly dispersed, and can provide a uniform porous inorganic paint film, thereby improving the coatability.

[0022]

According to the method for forming an inorganic coating film according to the first aspect of the present invention, the photocatalyst is fixed to the inorganic coating film and does not fall off. In addition, the second inorganic coating composition (A), (B)
And (C) are used as raw materials, and these raw materials are mixed, and the resulting mixture is subjected to hydrolysis and polycondensation reaction, and the adjusted weight average molecular weight is 900 or more in terms of polystyrene, so that cracks are less likely to occur. A coating film having excellent properties can be obtained.

In the method for forming an inorganic coating film according to the third and fourth aspects of the present invention, the solvent may contain a surfactant and / or a surfactant.
Or a drying control agent which is a solvent having a boiling point of 100 to 250 ° C,
For example, since it contains formamide, dimethylformamide, acetonitrile, dioxane, normal heptane, etc., it has a good affinity for inorganic paints and can be highly dispersed.
When drying at 0 ° C. or more, the surfactant and the drying control agent are decomposed, so that a homogeneous porous inorganic coating film can be obtained.

[0024]

The present invention will now be described by way of Examples and Comparative Examples.
This will be specifically described.

Example 1 Tetraethoxysilane as a silicon compound represented by the above general formula and IPA organosilica sol as colloidal silica (trade name: OSCAL143, manufactured by Catalyst Chemicals, Inc.)
2) Methyltrimethoxysilane was used as the silicon compound represented by the general formula, and dimethyldimethoxysilane was used as the silicon compound represented by the general formula.
100 parts by weight of methyltrimethoxysilane (hereinafter referred to as "part"), 10 parts of tetraethoxysilane, 90 parts of IPA organosilica sol, and 3 parts of dimethyldimethoxysilane
After mixing 0 parts and 100 parts of isopropyl alcohol (hereinafter referred to as IPA), 90 parts of water was added and stirred.
This is placed in a thermostat at 60 ° C. to obtain a weight average molecular weight (hereinafter referred to as Mw).
Was adjusted to 1500 to obtain an inorganic paint. Also,
As a photocatalyst, TiO ₂ (manufactured by Nippon Aerosil Co., Ltd .: trade name P)
-25) was dispersed in methanol to prepare a photocatalyst solution. The content of TiO ₂ with respect to the total amount of the photocatalyst solution is 5
% By weight. The obtained inorganic paint was applied to an alumina substrate washed with acetone, then a photocatalyst solution was applied, and then dried at 100 ° C. for 1 hour to obtain an inorganic paint film. Further, a second inorganic paint obtained by diluting the first inorganic paint obtained in Example 1 ten times with IPA was applied.

In order to evaluate the photocatalytic action of this inorganic paint film, the acetaldehyde removal rate was measured and the results are shown in Table 1. Here, the higher the acetaldehyde removal rate, the greater the photocatalytic action. The acetaldehyde removal rate was 50% in the container on which the inorganic paint film was formed.
ppm acetaldehyde was injected, irradiated with 10 W black light for 30 minutes, and measured using gas chromatography.

(Example 2) The inorganic coating film obtained in Example 1 was further immersed in a 0.1% aqueous sodium hydroxide solution for 24 hours and etched to obtain an inorganic coating film, and the acetaldehyde removal rate was reduced. The measured values are shown in Table 1.

Example 3 To 99 parts by weight of the photocatalyst solution obtained in Example 1, dodecyltrimethylammonium chloride (manufactured by NOF CORPORATION, trade name: Nissan Cation) was added at a ratio of 1 part by weight. An inorganic coating film was obtained and the acetaldehyde removal rate was measured in the same manner as in Example 1 except that the photocatalyst solution was used.

Comparative Example 1 To 100 parts of methyltrimethoxysilane, 10 parts of tetraethoxysilane, 90 parts of IPA organosilica sol,
After mixing 30 parts of dimethyldimethoxysilane and 100 parts of isopropyl alcohol (IPA), 90 parts of water was added and stirred. This was adjusted to a weight average molecular weight (hereinafter referred to as Mw) of 1500 in a thermostat at 60 ° C., and 20 parts of TiO ₂ (manufactured by Nippon Aerosil Co., Ltd., trade name: P-25) was added to this solution. Thus, an inorganic paint was obtained. This inorganic paint was applied to an alumina substrate washed with acetone, and dried at a temperature of 100 ° C. for 1 hour. The cured inorganic paint film was further immersed in a 0.1% aqueous sodium hydroxide solution for 24 hours and etched to obtain an inorganic paint film, and the acetaldehyde removal rate was measured.

[0030]

[Table 1]

As shown in Table 1, in the examples, the acetaldehyde removal rate of the inorganic paint film was larger than that in the comparative example.
It was confirmed that the oxidizing performance by photocatalysis was excellent, and the effects of deodorization, antibacterial and the like were great. In addition, the inorganic paint film of Example 1 had a high glossiness, and the inorganic paint film had good surface properties.

[0032]

According to the method for forming an inorganic paint film according to the first and second aspects of the present invention, since the photocatalyst is fixed to the inorganic paint film and does not fall off, the photocatalytic performance such as high oxidation performance is obtained. And an inorganic coating film having excellent surface properties of the inorganic coating film.

According to the method for forming a coating film of an inorganic paint according to the third and fourth aspects of the present invention, it has good affinity with the inorganic paint, can be highly dispersed, and has a surface activity when dried at 100 ° C. or more. Since the agent and the drying control agent are decomposed, a homogeneous porous inorganic coating film can be obtained, so that an inorganic coating film having higher photocatalytic performance such as oxidation performance can be obtained.

Continuation of front page (56) References JP-A-1-306476 (JP, A) JP-A-63-117074 (JP, A) JP-A-2-264074 (JP, A) JP-A-5-117590 (JP, A) JP-A-4-33843 (JP, A) JP-A-1-259076 (JP, A) JP-A-6-65012 (JP, A) JP-A-6-126244 (JP, A) JP-A-6-293879 (JP, A) JP-A-6-182299 (JP, A) JP-A-6-65527 (JP, A) JP-A-6-128533 (JP, A) JP-A-3-157125 (JP, A A) (58) Field surveyed (Int. Cl. ⁷ , DB name) B05D 1 / 36,1 / 38,5 / 00 B05D 7/24 C09D 5 / 14,5 / 16 C09D 183/04

Claims (4)

(57) [Claims] 1. The following compositions (A), (B) and (C) are used as raw materials, these raw materials are mixed, and the mixture is subjected to hydrolysis and polycondensation reaction to adjust the weight average molecular weight to polystyrene. After applying the first inorganic paint having a conversion of 900 or more to the base material, a photocatalyst dispersed in a solvent is applied, and the following compositions (A), (B) and (C) are used as raw materials. The raw materials are mixed, the mixture is hydrolyzed, and a weight-average molecular weight adjusted by performing a polycondensation reaction is applied with a second inorganic paint having a polystyrene equivalent of 900 or more, and a photocatalyst-containing coating film is formed. A method for forming a coating film of an inorganic paint, which is characterized by being formed. (A) a silicon compound represented by the following general formula and / or colloidal silica 20 to 200 parts by _{^{weight, Si (OR 1) 4 ------}} (B) silicon represented by the following general formula 100 compounds
Parts by weight, R ² Si (OR ¹ ) _3- (C) A silicon compound represented by the following general formula,
0 parts by ^{_{weight, R 2 2 Si (OR 1}} ) 2 ------ [In the general formula ~ general formula, R ^1, R ² represents a monovalent hydrocarbon group. ] 2. The method according to claim 1, wherein the second inorganic coating is obtained by reducing the concentration of the first inorganic coating. 3. The formation of an inorganic coating film according to claim 1, wherein the solvent contains a surfactant and / or a solvent having a boiling point of 100 to 250 ° C. (drying control agent). Method. 4. The method according to claim 1, wherein the drying control agent is at least one selected from the group consisting of formamide, dimethylformamide, acetonitrile, dioxane and normal heptane. A method for forming an inorganic paint film.