JPH08117684A - Treatment of coating film of inorganic coating material - Google Patents

Abstract

PURPOSE: To obtain a coating film capable of preventing the deposition of contaminant for a long time by applying an inorg. coating material contg. silicon and a hydrocarbonic group as the component, drying the coating material and then treating the surface of the coating film of the material with alkali, acid or steam. CONSTITUTION: When the coating film of an inorg. coating material is formed, an inorg. coating material contg. silicon and a hydrocarbonic group as the component is applied and dried, and then the surface of the coating film is treated with alkali, acid or steam. In this case, the alkali treatment is carried out by dipping the coated material in a soln. of pH>=9, and the acid treatment is carried out by dipping the coated material in a soln. of pH<=3. A material contg. a silicon compd. shown by Si(OR<1> )4 , colloidal silica, a silicon compd. shown by R<2> 2 Si(OR<1> )3 , and a silicon compd. shown by R<2> 2 Si(OR<1> )2 is used as the inorg. coating material. In the formulas, R<1> and R<2> are a univalent hydrocarbonic group.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating a coating film coated with an inorganic coating material containing silicon and a hydrocarbon group as components.

[0002]

2. Description of the Related Art Organic paints have the drawback that the organic resin deteriorates when used for a long period of time, and particularly when used outdoors, it is susceptible to discoloration due to deterioration due to ultraviolet rays. Therefore, various inorganic coating materials having weather resistance have been proposed. But,
In addition to discoloration, stains such as rain stains, dust, and exhaust gas may impair the appearance of the coating film. BACKGROUND ART In recent years, paints have been used for various materials such as building materials and automobiles, and it is required to maintain their beauty for a long time.

[0003]

One of the causes of adhesion of stains to the coating film is that the stains on the coating film are fixed by rain. For example, in the case of coating films for automobiles, water repellency increases when wax is applied, but on the contrary, stains of raindrops tend to be attached. That is, it is assumed that when the surface energy of the coating film decreases, stains are likely to adhere.

The present invention has been made in view of the above facts, and an object of the present invention is to provide a method for treating an inorganic paint coating film capable of preventing the adhesion of dirt for a long period of time.

Further, there is a demand for an inorganic coating material which does not cause cracks in the coating film as well as weather resistance of the coating film. Another object of the present invention is to provide a method for treating an inorganic paint coating film which has more excellent weather resistance and flexibility in addition to the above objects.

[0006]

A method for treating an inorganic paint coating film according to claim 1 of the present invention is a method of applying an inorganic paint containing silicon and a hydrocarbon group as components and drying the inorganic paint. It is characterized in that the surface of the coating film is treated with any one of alkali, acid and steam.

The method for treating an inorganic coating film according to claim 2 of the present invention is the same as the method for treating an inorganic coating film according to claim 1, wherein the alkali treatment is performed by immersing the article to be coated in a solution having a pH of 9 or more. It is characterized by doing.

The method for treating an inorganic coating film according to claim 3 of the present invention is the same as the method for treating an inorganic coating film according to claim 1, wherein the acid treatment is such that the article to be coated is immersed in a solution having a pH of 3 or less. It is characterized by doing.

The method for treating an inorganic coating film according to a fourth aspect of the present invention is the method for treating an inorganic coating film according to the first aspect, wherein the treatment with steam comprises exposing the article to be exposed to high-pressure steam. Characterize.

The method for treating an inorganic coating film according to claim 5 of the present invention is the method for treating an inorganic coating film according to any one of claims 1 to 4, wherein the component of the inorganic coating is (a) general. A silicon compound represented by the formula: Si (OR ¹ ) ₄ and / or colloidal silica of 20 to 200
Parts by weight, (b) 100 parts by weight of a silicon compound represented by the general formula: R ² Si (OR ¹ ) ₃ , and (c) silicon represented by the general formula: R ² ₂ Si (OR ¹ ) _2. The compound is contained in a proportion of 0 to 60 parts by weight, and (d) the weight average molecular weight of the inorganic coating material containing these is 1000 or more in terms of polystyrene. [The above R ¹ and R ² represent a monovalent hydrocarbon group. The method for treating an inorganic paint coating film according to claim 5 of the present invention is the method for treating an inorganic paint film according to any one of claims 1 to 4, wherein the component of the inorganic paint is (a) a general formula: The hydrolyzable organosilane represented by the following formula [1] was partially hydrolyzed in an organic solvent or water-dispersed colloidal silica under the condition of using 0.001 to 0.5 mol of water per 1 mol of X. A silica-dispersed oligomer solution of organosilane and R ³ _n SiX _4-n [1] [wherein, R ³ represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, n represents an integer of 0 to 3 and X represents a hydrolyzable group. (B) Polyorganosiloxane having a silanol group in the molecule represented by the following formula [2], and R ⁴ _a Si (OH) _b O _{(4-ab) / 2} [2] [In the formula, R ⁴ represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and a and b are 0.2 ≦ a ≦ 2 and 0.0001 ≦ b ≦, respectively. 3, a +
It is a number that satisfies the relationship of b <4. (C) a catalyst, and (D) the colloidal silica of the silica-dispersed oligomer solution contains 5 to 95% by weight of silica as a solid content, and at least 50 mol% of the hydrolyzable organosilane is contained in the above [ 1] n is 1 in the formula, and (e) 99 to 1 parts by weight of the polyorganosiloxane is contained in 1 to 99 parts by weight of the silica-dispersed oligomer solution. To do.

The present invention will be described in detail below. The present invention applies an inorganic coating material containing silicon and a hydrocarbon group as components, and after drying, the coating film surface of this inorganic coating material is treated with an alkali, an acid, or steam to form a coating film. This is a method of increasing the surface energy and making the coating film less likely to become dirty.

The inorganic coating material used in the present invention will be described. The inorganic paint contains silicon and a hydrocarbon group as components. As the above-mentioned inorganic coating, an inorganic coating having excellent weather resistance is more preferable in order to maintain the appearance of the coated film for a long period of time. Examples of such inorganic paints include the following inorganic paints.

A first example of the inorganic coating material is 20 to 200 parts by weight of a silicon compound having a general formula represented by the following formula [3] and / or colloidal silica, and a general formula: Si (OR ¹ ). ₄ [3] 100 parts by weight of a silicon compound represented by the following general formula [4], and a general formula: R ² Si (OR ¹ ) ₃ [4] A general formula represented by the following formula [5] 0-60 silicon compound
It is contained in a proportion of parts by weight. General formula: R ² ₂ Si (OR ¹ ) ₂ [5] In addition, the above R ¹ and R ² represent a monovalent hydrocarbon group.

The above silicon compound has the following general formula [6]:
It is what is represented. R² _nSi (OR¹)_4-n [6] [n = 0 to 3, indicating R¹, R²Is a monovalent hydrocarbon group
Show. ] R of the previous formula [6]¹, R²Is a monovalent hydrocarbon group
Without limitation, R ²As C1-8 substitution or
Represents an unsubstituted hydrocarbon group, such as a methyl group or ethyl group.
Group, propyl group, butyl group, pentyl group, hexyl group
Group, alkyl group such as heptyl group, octyl group, cyclopentyl group
Cycloalkyl groups such as ethyl and cyclohexyl groups, 2
-Ara such as phenylethyl group and 3-phenylpropyl group
Aryl group such as alkyl group, phenyl group and tolyl group, vinyl group
Group, alkenyl group such as allyl group, chloromethyl group, γ
-Chloropropyl group, 3,3,3-trifluoropropyl group, etc.
Halogen-substituted hydrocarbon group and γ-methacryloxy
Propyl group, γ-glycidoxypropyl group, 3,4-E
Poxycyclohexylethyl group, γ-mercaptopropy
And a substituted hydrocarbon group such as a rutile group. Above all synthetic
Because of its ease or availability, it has 1 to 4 carbon atoms.
A kill group and a phenyl group are preferred.

As R ¹ in the above formula [6], ^one having an alkyl group having 1 to 4 carbon atoms as a main raw material is used. In particular, n = 0
Examples of the tetraalkoxysilane include tetramethoxysilane and tetraethoxysilane. Examples of the organotrialkoxysilane with n = 1 include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane and phenyltrimethoxysilane. , Phenyltriethoxysilane, 3,3,3-trifluoropropyltrimethoxysilane and the like. Furthermore, n = 2
Examples of the diorganodialkoxysilane include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, and methylphenyldimethoxysilane. Examples of the triorganoalkoxysilane with n = 3 include trimethylmethoxysilane. , Trimethylethoxysilane, trimethylisopropoxysilane, dimethylisobutylmethoxysilane and the like.

The above R ¹ and R ² are represented by the above formulas [3], [4],
In [5], the same hydrocarbon group may be present or may be different.

The above-mentioned inorganic coating is prepared by, for example, diluting a silicon compound represented by the above formulas [3], [4] and [5] with a solvent, adding water or a catalyst as a curing agent, and hydrolyzing the compound. Also, it is prepared by performing a polycondensation reaction. The weight average molecular weight (Mw) of these silicon compounds is calculated in terms of polystyrene. At the time of this preparation, the weight average molecular weight (Mw) of the inorganic coating material is adjusted to 1000 or more in terms of polystyrene.
Weight average molecular weight (Mw) is 1000 in terms of polystyrene
If the amount is less than the above, curing shrinkage becomes large during the polycondensation reaction, and cracks are likely to occur in the coating film of the baked and dried inorganic coating material.

The above-mentioned inorganic coating material may be used in combination with the silicon compound represented by the above formula [3], or alternatively, may contain colloidal silica as a component. The colloidal silica is
It is a water-dispersible colloidal silica dispersed in water or an 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 the preparation of the inorganic coating material, the water-dispersible colloidal silica can use water existing as a component other than the solid content as a curing agent. Further, the organic solvent-dispersible colloidal silica can be easily prepared by substituting water for the organic solvent. 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. Ethylene glycol derivatives, diethylene glycol, diethylene glycol derivatives such as diethylene glycol monobutyl ether, and diacetone alcohol, and the like, and one or more of these may be used. Furthermore, in combination with a hydrophilic organic solvent, toluene, xylene, ethyl acetate, butyl acetate,
Methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketoxime and the like can also be used. The amount of the colloidal silica blended is the weight including the dispersion medium.

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

The organic solvent used for producing the inorganic coating is, for example, lower aliphatic alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol, ethylene glycol, ethylene glycol monobutyl ether, and ethylene glycol monoacetate acetate. Examples thereof include ethylene glycol derivatives such as ethyl ether, diethylene glycol, diethylene glycol derivatives such as diethylene glycol monobutyl ether, and diacetone alcohol. One or two of these may be mentioned.
More than one seed is used. Further, toluene, xylene, ethyl acetate, butyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methyl ethyl ketoxime, etc. can be used in combination with the hydrophilic organic solvent.

When preparing the above-mentioned inorganic paint, p of the inorganic paint is used.
It is desirable that H be 3.8 to 6. When the pH is in this range, the inorganic coating composition has good storage stability, and when it is out of this pH range, the period from the preparation period to the coating period is limited. The method of adjusting the pH is not limited, but for example, when the pH becomes less than 3.8 when the materials are mixed, it 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.
Further, depending on the pH, when the progress of the reaction is slow in the state where the molecular weight is small, it may be heated to accelerate the reaction,
The pH may be lowered with an acidic reagent to proceed the reaction, and then a basic reagent may be added to adjust the pH to a predetermined value.

Next, the inorganic coating material exemplified in the second example is prepared by subjecting a hydrolyzable organosilane represented by the following general formula [1] to an organic solvent or water-dispersed colloidal silica to obtain X.
A silica-dispersed oligomer solution of organosilane partially hydrolyzed under the condition of using 0.001 to 0.5 mol of water per 1 mol, and a general formula: R ³ _n SiX _4-n [1] ³ represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, n represents an integer of 0 to 3, and X represents a hydrolyzable group. ] A polyorganosiloxane having a silanol group in a molecule whose average composition formula is represented by the following formula [2], and an average composition formula: R ⁴ _a Si (OH) _b O _{(4-ab) / 2} [2 [Wherein, R ⁴ represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and a and b are 0.2 ≦ a ≦ 2 and 0.0001 ≦ b, respectively. ≦ 3, a +
It is a number that satisfies the relationship of b <4. ] It consists of a catalyst. Furthermore, in the above-mentioned inorganic coating material, the silica-dispersed oligomer solution contains silica in an amount of 5 to 95% by weight as a solid content, and at least 5
0 mol% is an organosilane in which n in the formula [1] is 1, and the silica-dispersed oligomer solution is used in an amount of 1 to 99%.
99 to 100 parts by weight of the above polyorganosiloxane based on parts by weight.
Contains 1 part by weight.

The silica-dispersed oligomer of the silica-dispersed oligomer solution is the main component of the base polymer having a hydrolyzable group as a functional group which is involved in the curing reaction when forming a coating film. This silica-dispersed oligomer is an organic solvent,
Alternatively, the colloidal silica dispersed in water may be added to the above formula [1]
It is obtained by partially hydrolyzing the hydrolyzable organosilane with water in colloidal silica or water added separately, by adding one or more hydrolyzable organosilanes represented by

R ³ of the hydrolyzable organosilane represented by the above formula [1] is a substituted or unsubstituted 1 having 1 to 8 carbon atoms.
A valent hydrocarbon group is shown, and specifically, a hydrocarbon group similar to the above R ² is exemplified.

Examples of X which represents the above hydrolyzable group include an alkoxy group, an acetoxy group, an oxime group, an enoxy group, an amino group, an aminoxy group and an amide group. Among these, the alkoxy group is preferable because it is easily available and the silica dispersion oligomer solution is easily prepared.

Such a hydrolyzable organosilane is
Monofunctional, di-, tri-, and tetra-functional alkoxysilanes, acetoxysilanes, oximesilanes, and enoxysilanes in which n in the chemical formula represented by the above formula [1] is an integer of 0 to 3 And aminosilanes, aminoxysilanes, amidosilanes and the like. Among these, alkoxysilanes are preferable because they are easily available and a silica dispersion oligomer solution is easily prepared. Examples of the tetraalkoxysilane with n = 0 include tetramethoxysilane and tetraethoxysilane,
Examples of the organotrialkoxysilane having n = 1 include methyltrimethoxysilane, methyltriethoxysilane, methyltriisopropoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and 3,3,3-trifluoropropyltrimethoxysilane. Is exemplified. Further, as a diorganodialkoxysilane of n = 2,
Examples of dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, methylphenyldimethoxysilane, and the like are given. As triorganoalkoxysilane of n = 3,
Examples include trimethylmethoxysilane, trimethylethoxysilane, trimethylisopropoxysilane, and dimethylisobutylmethoxysilane. Furthermore, an organosilane compound generally called a silane coupling agent is also included in the above alkoxysilanes.

It is necessary that at least 50 mol% of the above hydrolyzable organosilane is a trifunctional organosilane represented by the formula [1] where n is 1. The proportion of the trifunctional organosilane is preferably 60 mol% or more, more preferably 70 mol% or more. If this content is less than 50 mol%, sufficient coating film hardness cannot be obtained, and the dry curability tends to be poor.

The colloidal silica in which the above hydrolyzable organosilane is dispersed in an organic solvent or water enhances the hardness of the cured coating film of the inorganic coating material. Examples of the colloidal silica include the water-dispersible colloidal silica and the organic solvent-dispersible colloidal silica described above in the first exemplary inorganic coating material.

The colloidal silica contains silica in the range of 5 to 95% by weight as a solid content. This content is 1
0 to 90% by weight is preferable, more preferably 20 to 85
% By weight. When the content is less than 5% by weight, the hardness of the coating film of the inorganic coating cannot be obtained, and when the content exceeds 95% by weight, it becomes difficult to uniformly disperse silica, and problems such as easy gelation occur. Cheap.

The hydrolyzable organosilane represented by the above formula [1] is partially hydrolyzed in an organic solvent or colloidal silica dispersed in water to obtain a silica-dispersed oligomer solution of organosilane. The amount of water relative to the hydrolyzable organosilane was 0.
001 to 0.5 mol is preferable. If the amount of water is less than 0.001 mol, sufficient partial hydrolysis cannot be obtained, and if it exceeds 0.5 mol, the stability of the partial hydrolyzate becomes poor. The method of partial hydrolysis is not particularly limited, and it is sufficient to mix the hydrolyzable organosilane and colloidal silica and add predetermined water, at which time the partial hydrolysis reaction proceeds at room temperature. In addition, you may heat at 60-100 degreeC in order to accelerate | stimulate the said partial hydrolysis reaction. Further, for the purpose of promoting partial hydrolysis reaction, hydrochloric acid, acetic acid, halogenated silane, chloroacetic acid, citric acid, benzoic acid, dimethylmalonic acid, formic acid, propionic acid, glutaric acid, glycolic acid, maleic acid, malonic acid, Organic and inorganic acids such as toluene sulfonic acid and oxalic acid may be used as catalysts.

In order to obtain stable performance of the above-mentioned silica-dispersed oligomer solution for a long period of time, the pH of the solution is 2.0 to 7.0,
The pH is preferably 2.5 to 6.5, more preferably the pH.
Is preferably 3.0 to 6.0. When the pH is out of this range, particularly when the amount of water is 0.3 mol or more relative to 1 mol of the hydrolyzable group (X), the long-term performance deterioration of the silica-dispersed oligomer solution is remarkable. The method of adjusting the pH is not limited, but when the pH of the liquid deviates from the above range to the acidic side, it may be adjusted by adding a basic reagent such as ammonia or ethylenediamine. When the pH deviates to the basic side, hydrochloric acid is added. ,
It may be adjusted by adding an acidic reagent such as nitric acid or acetic acid.

The silanol group-containing polyorganosiloxane of the above-mentioned inorganic paint has an average compositional formula represented by the above formula [2].

R ⁴ in the above formula [2] represents a substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and specific examples thereof include the same hydrocarbon group as R ² described above. However, preferably, an alkyl group having 1 to 4 carbon atoms, phenyl group, vinyl group, γ-glycidoxypropyl group, γ-methacryloxypropyl group, γ-aminopropyl group, 3,3,3-trifluoro group It is a substituted hydrocarbon group such as a propyl group, more preferably a methyl group and a phenyl group. Further, a and b in the formula [2] are 0.2 ≦ a ≦ 2 and 0.0001, respectively.
It is a number that satisfies the relationship of ≦ b ≦ 3 and a + b <4. If a is less than 0.2 or b is more than 3, there is an inconvenience such as cracking in the cured coating film, and if a is more than 2.0 and less than 4 or b is less than 0.0001, curing proceeds well. do not do.

As the polyorganosiloxane containing a silanol group, methyltrichlorosilane, dimethyldichlorosilane, phenyltrichlorosilane, diphenyldichlorosilane, or one or a mixture of two or more alkoxysilanes corresponding thereto is known. It can be obtained by hydrolysis with a large amount of water according to the method.
In order to obtain the polyorganosiloxane containing the silanol group, when hydrolyzed with an alkoxysilane,
A small amount of unhydrolyzed alkoxy groups may remain. That is, a polyorganosiloxane in which a silanol group and an extremely small amount of an alkoxy group coexist may be obtained, but such a polyorganosiloxane may be used.

The above catalyst accelerates the condensation reaction between the above-mentioned silica-dispersed oligomer solution and polyorganosiloxane,
It cures the coating film. Examples of the catalyst include alkyl titanates, tin octylate and diptyltin dilaurate, metal salts of carboxylic acids such as dioctyltin dimaleate, dibutylamine-2-hexoate, dimethylamine acetate, amine salts such as ethanolamine acetate, Carboxylic acid quaternary ammonium salts such as tetramethylammonium acetate, amines such as tetraethylpentamine, N-β-aminoethyl-γ-aminopropyltrimethoxysilane, N-β-aminoethyl-γ-aminopropylmethyldimethoxy Amine-based silane coupling agents such as silanes, acids such as p-toluenesulfonic acid, phthalic acid and hydrochloric acid, aluminum compounds such as aluminum alkoxides and aluminum chelates, alkali catalysts such as sodium hydroxide, tetraisopropyl titanate , Tetrabutyl titanate, titanium compounds such as titanium tetraacetyl acetonate, methyltrichlorosilane, dimethyldichlorosilane, halogenated silane such as trimethyl monochloro silane, and the like.

The silica dispersion oligomer solution and the polyorganosiloxane are compounded in a proportion of 1 to 99 parts by weight of the silica dispersion oligomer solution and 99 to 1 parts by weight of the polyorganosiloxane, preferably the silica. The dispersion oligomer solution is 5 to 95 parts by weight, and the polyorganosiloxane is 95 to 5 parts by weight, and more preferably, the silica dispersion oligomer solution is 10 to 9 parts by weight.
90 to 90 parts by weight of the above polyorganosiloxane
10 parts by weight. If the proportion of the silica-dispersed oligomer solution is less than the above range, it is difficult to cure at room temperature, and sufficient hardness of the coating film cannot be obtained. If the ratio of the silica-dispersed oligomer solution is more than the above range, the curability becomes unstable.

The content of the catalyst is preferably 0.0001 to 10 parts by weight based on 100 parts by weight of the total amount of the silica-dispersed oligomer solution and the polyorganosiloxane. It is more preferably 0.0005 to 8 parts by weight, and most preferably 0.0007 to 5 parts by weight. 0.00 catalyst
If it is less than 01 parts by weight, it will not cure at room temperature, and if it exceeds 10 parts by weight, heat resistance and weather resistance will be poor.

The hydrolyzable group contained in the silica-dispersed oligomer and the silanol group in the polyorganosiloxane undergo a condensation reaction in the presence of a catalyst at room temperature or at a low temperature of 200 ° C. or lower to form a coating film. To do. Therefore, the inorganic coating material is cured at room temperature with little influence of humidity. Further, the condensation reaction can be promoted by the above-mentioned low temperature heating.

The above-mentioned inorganic paint can be diluted with various organic solvents for easy handling. The type of the organic solvent is appropriately selected depending on the types and molecular weights of the monovalent hydrocarbon groups in the silica-dispersed oligomer solution and the polyorganosiloxane. Examples of the organic solvent include the same organic solvents as described in the inorganic coating shown in the first example.

In the present invention, the above inorganic coating material is applied and dried. The method of applying the above-mentioned inorganic paint is brush coating,
Various coating methods such as spray coating, dipping, curtain and knife coating can be adopted. At the time of coating, it may be appropriately diluted with an organic solvent, if necessary. The drying conditions of the above-mentioned inorganic paint are appropriately selected depending on the components of the inorganic paint.

In the present invention, the surface of the coating film of the above-mentioned inorganic paint is treated with any of alkali, acid and steam. This processing method will be specifically described.

In the case of treating with the above alkali, for example,
The article to be coated is dipped in an alkaline solution having a pH of 9 or more. pH
If the alkali is less than = 9, a long treatment time is required and the treatment efficiency is poor. The alkaline solution is not limited, but is, for example, an aqueous solution of an alkali such as sodium hydroxide (NaOH) or calcium hydroxide (Ca (OH) ₂ ), or an alkaline earth metal hydroxide, and aqueous ammonia. , An aqueous solution of amines. An aqueous solution of sodium hydroxide (NaOH) is preferable from the viewpoint of high processing speed. When the surface of the coating film is treated with the above alkaline solution, the organic groups present on the outermost surface of the coating film are dissolved and the amount of hydroxyl groups present on the surface is increased, so that the coating film has an increased surface energy.
The treatment time with the alkaline solution is appropriately selected depending on the pH and the composition of the inorganic coating material. It is necessary to shorten the treatment time for a strong alkaline solution having a pH of 12 or more. When the treatment time is too long, irregularities are generated on the surface of the coating film, and stains are easily attached to the irregularities, so that the effect of preventing stains decreases. In addition, the rate at which the surface of the coating film dissolves also differs depending on the curing conditions of the coating film. Therefore, when dried at a low temperature, the rate of dissolution of the coating film surface is fast, so that the treatment time is short, and when dried at a high temperature of about 200 ° C., it is preferable to lengthen the treatment time as the temperature rises. If the coating composition is left to stand for a long time after drying, the coating film may be hardened in some cases. Therefore, it is preferable to carry out the treatment early after drying because the treatment time can be shortened.

In the case of treating with the above-mentioned acid, for example, since the coating film containing a silicon component has the property of acid resistance,
It is preferable to immerse the article to be coated in an acidic solution of 3 or less. When the drying temperature is also low, the processing time can be shortened, which is preferable. The method of treating with the acid requires a longer treatment time than the treatment with the alkali, but the treatment with the alkali has the same effect and increases the surface energy of the coating film.

In the case of treating with the above-mentioned steam, for example, a method of exposing the object to be coated to high-pressure steam can be mentioned. When exposed to the water vapor, the unreacted alkoxide existing on the surface of the coating film is hydrolyzed to form a hydroxyl group, so that the same effect as the treatment with the alkali or acid is produced. Normal pressure steam may be used, but exposure to high pressure steam such as in an autoclave is preferable because the processing time can be shortened. The method of treating with steam is particularly effective when a large amount of unreacted alkoxide remains. Therefore, it is particularly effective for the inorganic paints exemplified above.

[0045]

The method of treating a coating film of an inorganic paint according to any one of claims 1 to 4 of the present invention comprises applying a coating film of an inorganic coating material containing silicon and a hydrocarbon group as components, drying the coating film, and then coating the coating film of this inorganic coating material. Since the surface is treated with any one of alkali, acid and water vapor, the amount of hydroxyl groups present on the surface of the coating film increases, so that the surface energy of the coating film increases. Therefore, it is possible to obtain a coating film in which dirt is not easily attached to the coating film.

In the method for treating an inorganic paint coating film according to any one of claims 5 to 6 of the present invention, since an inorganic paint having a composition that does not easily generate cracks in the coating film is used, a flexible inorganic paint coating film is obtained. To be

[0047]

EXAMPLES Next, examples of the present invention and comparative examples will be described. The molecular weight is a value determined by gel permeation chromatography (GPC) using a measurement model HLC8020 (manufactured by Tosoh Corporation) and obtained from a calibration curve of standard polystyrene.

Example 1 An inorganic coating material (A) was prepared under the following conditions. IPA organosilica sol (Catalyst Kasei Co., Ltd .: trade name OSCAL1432) as colloidal silica, methyltrimethoxysilane as the silicon compound represented by the formula [4], and dimethyldimethoxy as the silicon compound represented by the formula [5]. Silane was used.

60 parts of IPA organosilica sol was added to 100 parts by weight of methyltrimethoxysilane (hereinafter referred to as "part").
Part, 30 parts of dimethyldimethoxysilane and 100 parts of isopropyl alcohol (IPA) were mixed, and then water 12
0 part was added and stirred. The weight average molecular weight of this was adjusted to 1200 in a constant temperature bath at 60 ° C. to obtain an inorganic coating (A).

Next, a commercially available white acrylic paint is spray-coated on the alumina substrate (size 150 mm × 70 mm) washed with acetone so as to have a thickness of 5 μm after drying 60
It was dried at 0 ° C for 10 minutes. After that, the above-mentioned inorganic coating material (A) is applied thereon so that the thickness of the coating film of the inorganic coating material after drying becomes 10 μm, and the coating material is dried at 150 ° C. for 20 minutes. ) Was dipped in a 5% by weight aqueous solution (pH = 13) for 30 minutes. The water contact angle of the coating changed from 75 ° to 58 ° before and after immersion.

Example 2 An inorganic coating film was formed in the same manner as in Example 1 except that the inorganic coating material (A) was applied in Example 1 and dried at 130 ° C. for 20 minutes. Calcium hydroxide (Ca (OH))
_It was immersed in a 1% by weight aqueous solution of ₂ ) (pH = 11) for 60 minutes. The water contact angle of the coating before and after dipping is 75 ° to 6 °
Changed to 3 °.

Example 3 An inorganic coating material (B) was prepared under the following conditions. First, (B-1 solution) was prepared as a silica-dispersed oligomer solution, and (B-2 solution) was prepared as a polyorganosiloxane.

(B-1 solution) In a flask equipped with a stirrer, a heating jacket, a condenser, and a thermometer, methyl alcohol-dispersed colloidal silica sol MA-ST (particle size 10 to 20 mμ, solid content 30%, water 0.5). %, Manufactured by Nissan Chemical Industries, Ltd.), 68 parts of methyltrimethoxysilane, 18 parts of dimethyldimethoxysilane,
2.7 parts of water and 0.1 part of acetic anhydride were added, and the mixture was partially hydrolyzed at 80 ° C. for 3 hours with stirring and cooled. Then, the solid content was 36% when left at room temperature for 48 hours. Hereinafter, this silica-dispersed oligomer solution was treated with (B-
It is referred to as 1 liquid).

The number of moles of water relative to 1 mol of the hydrolyzable group was 0.4 mole, the content of silica in (B-1 solution) was 40.2%, and n = 1 was added. The mol% of the decomposable group-containing organosilane was 77 mol%.

(B-2 solution) A mixed solution of 220 parts (1 mol) of methyltriisopropoxysilane and 150 parts of toluene was prepared. Next, the above mixed solution was put into a flask equipped with a stirrer, a heating jacket, a condenser, a dropping funnel and a thermometer, and 108 parts of a 1% hydrochloric acid aqueous solution was added dropwise thereto over 20 minutes to obtain methyltriisopropoxysilane. It was hydrolyzed. After 40 minutes from the dropping, stirring was stopped and the mixture was allowed to stand to separate into two layers. Of this layer, the lower layer mixed solution of water and isopropyl alcohol containing a small amount of hydrochloric acid was separated and removed, and then the remaining toluene resin solution was washed with water to remove hydrochloric acid, and toluene was further removed under reduced pressure. By diluting the component with isopropyl alcohol, a 40% isopropyl alcohol solution of a silanol group-containing organopolysiloxane having an average molecular weight of about 2000 was obtained. Less than,
This solution is referred to as (B-2 solution).

50 parts of the prepared solution B-1 and 5 parts of solution B-2 were prepared.
0 part and 2 parts of N-β-aminoethyl-γ-aminopropylmethyldimethoxysilane as a catalyst were mixed to obtain an inorganic coating material (B).

Next, a commercially available white acrylic paint was dried on an alumina substrate (size 150 mm × 70 mm) washed with acetone and then spray-painted to a thickness of 5 μm, and dried at 60 ° C. for 10 minutes. After that, the above inorganic coating material (B) is applied on this so that the thickness of the coating film of the inorganic coating material after drying becomes 10 μm, and the coating material is dried at 130 ° C. for 30 minutes, and then this coating object is treated with sodium hydroxide (NaOH). ) Was dipped in a 5% by weight aqueous solution (pH = 13) for 2 hours. Before and after soaking
The contact angle of water on the coating changed from 90 ° to 60 °.

Example 4 An inorganic coating film was formed in the same manner as in Example 3 except that the inorganic coating material (B) was applied in Example 3 and dried at 60 ° C. for 20 minutes. Calcium hydroxide (Ca (O
It was immersed for 60 minutes in a 1% by weight aqueous solution of H) ₂ ) (pH = 11). The water contact angle of the coating changed from 90 ° to 56 ° before and after immersion.

Example 5 An inorganic paint coating film was formed in the same manner as in Example 3 except that the inorganic paint (B) was applied in Example 3 and dried at 130 ° C. for 30 minutes. This coated object was left for 24 hours in a thermo-hygrostat having a temperature of 80 ° C. and a relative humidity of 90%. The water contact angle of the coating changed from 90 ° to 72 ° before and after standing.

Example 6 An inorganic coating film was formed in the same manner as in Example 3 except that the inorganic coating material (B) was applied in Example 3 and dried at 60 ° C. for 20 minutes. An aqueous solution of 5 wt% hydrochloric acid (pH = 1
The following) was immersed for 24 hours. The water contact angle of the coating changed from 90 ° to 65 ° before and after immersion.

Comparative Example 1 The inorganic coating material (A) was applied and dried under the same conditions as in Example 1 except that the alkali immersion was not performed.

Comparative Example 2 The inorganic coating material (B) was applied and dried under the same conditions as in Example 3 except that the alkali immersion was not performed.

The stains of the samples obtained in Examples 1 to 6 and Comparative Examples 1 and 2 after standing were evaluated. The stain was measured as follows. The above sample was left for 6 months while being exposed to the open air. The color stimulus value (Y) was measured using a color difference meter (Nippon Denshoku Industries Co., Ltd .: Σ80) before and after standing. The change rate (ΔY) of the stimulus value of this color was obtained.
The larger the rate of change (ΔY), the worse the stain. ΔY (%) = [1- (Y after leaving / Y before leaving)] × 1
00 As shown in Table 1, in each of the examples, the change rate (ΔY) of the color stimulus value was smaller than that of the comparative example.

The coating films of Examples 1 to 6 had no abnormal appearance such as discoloration and generation of cracks after the treatment and after standing.

[0065]

[Table 1]

[0066]

EFFECTS OF THE INVENTION In the method for treating a coating film of an inorganic paint according to claims 1 to 4 of the present invention, the amount of hydroxyl groups present on the surface of the coating film increases, so that the surface energy of the coating film increases. As a result, the coating film of the inorganic paint treated by the method of the present invention is less likely to have dirt attached.

In addition to the above effects, the method of treating an inorganic paint coating film according to claims 5 to 6 of the present invention has the above composition of the inorganic paint composition, so that cracks are less likely to occur in the coating film. Excellent weather resistance.

Continuation of front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical indication location C09D 183/04 PMS (72) Inventor Takeyuki Yamaki 1048 Kadoma, Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (6)

[Claims] 1. An inorganic coating material containing silicon and a hydrocarbon group as components is applied, dried, and then the surface of the coating film of this inorganic coating material is treated with an alkali, an acid or steam. A method for treating an inorganic paint coating film. 2. The method for treating an inorganic coating film according to claim 1, wherein the treatment with the alkali comprises immersing the article to be coated in a solution having a pH of 9 or more. 3. The method of treating an inorganic coating film according to claim 1, wherein the acid treatment comprises immersing the article to be coated in a solution having a pH of 3 or less. 4. The method for treating an inorganic coating film according to claim 1, wherein the treatment of the steam comprises exposing the article to be coated to high-pressure steam. 5. The component of the inorganic coating comprises (a) a silicon compound represented by the general formula: Si (OR ¹ ) ₄ and / or colloidal silica of 20 to 200.
Parts by weight, (b) 100 parts by weight of a silicon compound represented by the general formula: R ² Si (OR ¹ ) ₃ , and (c) silicon represented by the general formula: R ² ₂ Si (OR ¹ ) _2. A compound is contained in a proportion of 0 to 60 parts by weight, and (d) the weight average molecular weight of the inorganic coating material containing these is 1000 or more in terms of polystyrene, wherein the weight average molecular weight is 1000 or more. The method for treating an inorganic paint coating film as described above. [The above R ¹ and R ² represent a monovalent hydrocarbon group. ] 6. The component of the above-mentioned inorganic coating material is (a) water in an amount of X1 mol in colloidal silica in which a hydrolyzable organosilane represented by the following general formula [1] is dispersed in an organic solvent or water. A silica-dispersed oligomer solution of organosilane partially hydrolyzed under the condition of using 0.001 to 0.5 mol, and R ³ _n SiX _4-n [1] [wherein R ³ is the same or different substitution or It shows an unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, n is an integer of 0 to 3, and X is a hydrolyzable group. (B) Polyorganosiloxane having a silanol group in the molecule represented by the following formula [2], and R ⁴ _a Si (OH) _b O _{(4-ab) / 2} [2] [In the formula, R ⁴ represents the same or different substituted or unsubstituted monovalent hydrocarbon group having 1 to 8 carbon atoms, and a and b are 0.2 ≦ a ≦ 2 and 0.0001 ≦ b ≦, respectively. 3, a +
It is a number that satisfies the relationship of b <4. (C) a catalyst, and (D) the colloidal silica of the silica-dispersed oligomer solution contains 5 to 95% by weight of silica as a solid content, and at least 50 mol% of the hydrolyzable organosilane is contained in the above [ 1] In the formula, n is 1 and (e) the polydisperse oligomer is contained in an amount of 99 to 1 part by weight based on 1 to 99 parts by weight of the silica-dispersed oligomer solution. The method for treating an inorganic coating film according to any one of claims 1 to 4.