JPH0786183B2 - Coating composition for coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention has excellent heat resistance, abrasion resistance, chemical resistance, weather resistance, high hardness, and the like on the surface of metal, ceramics, glass, cement, etc. The present invention relates to a silicone-based coating composition for coating, which can form a high-gloss, thick coating film and has excellent long-term storage stability.

(Prior art) The surface of various molded products such as metals and ceramics is coated with a silicone-based polymer composition to provide smoothness, or scratch resistance, chemical resistance, corrosion resistance, weather resistance and water resistance are improved. Is being done. For example, JP-A-53-
In 88099, methylpolysilsesquioxane (silsesquioxane means the number of oxygen atoms to a silicon atom) obtained by hydrolyzing and polymerizing methyltrichlorosilane in a ketone-ether solvent in the presence of an amine. The ratio of 1.
5, referred to as siloxane).
This methyl polysilsesquioxane has a molecular weight of approximately 9,000-
It is 100,000 and soluble in organic solvents. When a coating film is formed using this paint containing methylpolysilsesquioxane, the film has heat resistance of 400 ° C. or higher. However,
It is not practical because it requires a long time of 2 hours or more at 200 ° C for curing. Furthermore, since the volume contracts due to the dehydration reaction at the time of curing, there is a defect that cracking occurs when the film is thickened.

Japanese Patent Publication No. 53-5042 discloses a coating composition containing a reaction condensate obtained by adding methyltrimethoxysilane to aqueous colloidal silica and adjusting the pH with an organic acid, and a pigment (extrinsic pigment). . According to this reaction, the hydrolysis and condensation of methyltrimethoxysilane proceed, and at the same time, the active silanol on the surface of the silica particles of colloidal silica also participates in the condensation reaction. Therefore, when the hydrolysis / condensation reaction proceeds excessively, the active silanol on the surface of the silica particles participates in the reaction, and the silica particles are likely to aggregate / gel. Therefore, it is necessary to set the reaction conditions to extremely mild conditions. Moreover, the resulting paint is poorly stable due to the presence of much more water than is needed for hydrolysis and therefore must be used within 24 hours of preparation. Further, since the condensation degree of the methyltrimethoxysilane condensate, which is a film forming component when forming the coating film, is low, there is a drawback that cracks occur when the film thickness is 3 μm or more. The surface of the coating film is inferior in smoothness and gloss is poor.

JP-A-62-105987 discloses a coating composition comprising a reaction mixture obtained by adding an aqueous solution of an acid to a mixture of tetraalkyl silicate and organosilica sol. This paint is used to coat the surface of the ceramic substrate to provide smoothness. This composition has an advantage that the molecular weight of the obtained polymer can be controlled by the amount of water added at the time of preparation and the addition rate. further,
Since the tetrafunctional tetraalkyl silicate is used, the coating film obtained by using the above composition is extremely excellent in heat resistance. However, the disadvantage that the silica particles of the organosilica sol react with the silanol groups generated by the reaction of the tetraalkyl silicate and water, causing aggregation and gelation of the silica particles. Japanese Patent Publication Sho 53 using colloidal silica
This is similar to the case of the −5042 publication. Furthermore, when this composition is prepared, the amount of water added is adjusted to control the hydrolysis of the tetraalkyl silicate, leaving the alkoxy groups in place to stabilize the resulting reaction mixture. Thus, since the alkoxy group remains in the polymer, it is necessary to eliminate the alkoxy group when the coating film is cured in order to form a coating film using this paint. Therefore, a post-process of baking at a high temperature of 500 ° C or higher is required during curing.

For the purpose of improving the above composition, the inventors have already proposed a coating composition obtained by reacting a condensate of a predetermined molecular weight obtained by hydrolyzing and condensing an alkoxysilane with an organosilica sol. (Japanese Patent Application Sho 62-331028
Issue).

Since this coating composition is prepared by using the condensate having the above-mentioned predetermined molecular weight, the condensate reacts with the silica particles of the organosilica sol to form a uniform and stable composition. However, the above-mentioned organosilica sol has poor reactivity because the surface of silica particles is alkoxylated with alcohol or the like as a dispersion medium. When the reaction temperature is raised to increase the reactivity, the silica particles are condensed or gelled. Thus, in the above method, it is difficult to select reaction conditions for preparing the composition.

(Problems to be Solved by the Invention) The present invention is to solve the above-mentioned conventional problems, and an object thereof is to provide a silicone-based coating composition for coating the surface of a metal or ceramic molded body. And to provide a coating composition having the following properties: A coating composition having excellent storage stability and capable of being stored for a long time without gelation; at a high temperature when preparing a coating film. A coating composition that does not require long-term curing treatment and does not cause cracks or the like even when forming a relatively thick coating film; and has excellent gloss, high hardness, and A coating composition capable of forming a coating film having excellent adhesion.

(Means and Actions for Solving the Problems) The coating composition for coating of the present invention is a coating composition containing surface-modified colloidal silica and organopolycycloxane; Silica is 30 to 90% by weight based on the total solid content, and the organopolysiloxane is contained in a ratio of 70 to 10% by weight based on the total solid content;
The surface-modified colloidal silica comprises an alkoxysilane compound having two or more alkoxy groups (having 1 to 8 carbon atoms) in the molecule, and / or two or more alkoxy groups (1 to 8) in the molecule. A colloidal silica comprising silica particles surface-modified with an alkoxysilane low condensate having 8 carbon atoms), said surface-modified colloidal silica comprising said alkoxysilane compound and / or alkoxysilane low The condensate is contained in an amount of 10 to 80% by weight in terms of solid content, and the silica particles in a proportion of 90 to 20% by weight in terms of solid content; and the organopolysiloxane has the general formula RSi (OR ') ₃ (wherein , R is an organic group having 1 to 8 carbon atoms,
R'is a condensate of an organoalkoxysilane represented by an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 4 carbon atoms, and has a polystyrene reduced weight average molecular weight of 500 to 10,000; Thereby, the above object is achieved.

The alkoxysilane compound for preparing the surface-modified colloidal silica contained in the composition of the present invention is at least one selected from the following formulas (I), (II) and (III). The low-condensate of the compound is a low-condensate obtained by hydrolyzing and condensing at least one selected from the group consisting of the compounds (I) to (III) and the compound of the following formula (IV).

Here, R ¹ , R ² , and R ³ are each independently an organic group having 1 to 8 carbon atoms, such as an alkyl group such as a methyl group, an ethyl group, a propyl group, or a butyl group; a phenyl group, a tolyl group, or a xylyl group. Aryl groups such as γ-chloropropyl group, vinyl group, γ-glycidoxypropyl group, γ-methacryloyloxypropyl group, γ-mercaptopropyl group, γ-aminopropyl group, 3,4-epoxycyclohexyl group And so on. R ⁴ , R ⁵ , R ⁶ and R ⁷ are each independently an alkyl group, a haloalkyl group, a cycloalkyl group, an aryl group,
It is an aralkyl group or an acyl group.

Among the above-mentioned alkoxysilane compounds, examples of the compound represented by the formula (I) include tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, and tetraphenoxysilane. Expression (I
The compounds represented by I) include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, and phenyl. Trimethoxysilane, phenyltriethoxysilane,
γ-chloropropyltrimethoxysilane, γ-chloropropyltriethoxysilane, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ
-Methacryloxypropyltrimethoxysilane, γ-
Examples include mercaptopropyltrimethoxysilane, γ-aminopropyltrimethoxysilane, and 3,4-epoxycyclohexylethyltriethoxysilane. Examples of the compound represented by the formula (III) include dimethyldimethoxysilane,
Examples include dimethyldiethoxysilane, dimethyldipropoxysilane, diphenyldimethoxysilane, and diphenyldiethoxysilane. Examples of the compound represented by the formula (IV) include trimethyltoxysilane, trimethylethoxysilane, trimethylpropoxysilane, trimethylbutoxysilane, triphenylmethoxysilane, triphenylethoxysilane, and γ-glycidoxypropylmethyldimethoxysilane.

The low-condensation product of the above-mentioned alkoxysilane compound is produced by a known production method, that is, by adding water to the above-mentioned alkoxysilane compound and further adding an acid catalyst described later, if necessary, to carry out a condensation reaction. Is prepared. The molecular weight of the obtained condensate is preferably about 200 to 1000.

The colloidal silica used in the present invention is a dispersion liquid in which ultrafine particles of silicic acid anhydride are dispersed in a solvent. The particle size of the silica particles is 5 to 200 mμ. When the particle size is below 5mμ,
When a coating film is formed using the obtained paint and cured, cracks are likely to occur. On the other hand, if it exceeds 200 mμ, the film-forming property is poor and the hardness and smoothness of the obtained coating film are poor.
It is preferably 10 mμ to 20 mμ. Examples of the solvent include alcohols such as methanol, ethanol, isopropanol, butanol; acetone, methyl ethyl ketone,
Ketones such as methyl isobutyl ketone; methyl acetate,
Esters such as ethyl acetate and butyl acetate; ethers such as diisopropyl ether and glycol ether; and mixtures thereof. Although it is possible to use aqueous colloidal silica dispersed in water, either mix organic solvent-dispersed colloidal silica or use water in an organic solvent in the required amount so that a large amount of water is not mixed into the reaction system. It is preferable to use by replacing by distillation. As such colloidal silica, for example, methanol silica sol, isopropanol silica sol manufactured by Nissan Chemical Industries, Ltd., and Snowtex; Oscar manufactured by Catalysts & Chemicals Co., Ltd. are commercially available. In both cases, the solid content concentration is 10 to 40% by weight.

The amount of the alkoxysilane compound and / or its low condensate blended with the colloidal silica is such that a monomolecular film of the alkoxysilane compound and / or its low condensate is formed on the surface of the silica particles of the colloidal silica. It is preferable. Therefore, the amount is determined by the particle size of the silica particles of colloidal silica. Specifically, the alkoxysilane compound and / or its low condensate in terms of solid content is in the range of about 10 to 80% by weight, preferably 10 to 50% by weight, and the colloidal silica is 90 to 20% by weight, preferably 90%.
It is contained in a proportion of up to 50% by weight. When the amount of the alkoxysilane compound and / or its low condensate is less than about 10% by weight, the colloidal silica is not sufficiently surface-modified, resulting in poor smoothness of the coating film formed from the finally obtained coating composition. The gloss is also bad. The hardness of the film is also insufficient. Above about 80% by weight, the reaction solution becomes cloudy due to the agglomeration of colloidal silica, which causes whitening of the film formed from the final coating composition.

An acid catalyst is optionally used in the reaction of the colloidal silica with the alkoxysilane compound and / or its low condensate. The acid catalyst has a function of promoting the polymerization reaction of alkoxysilane, its low condensate and colloidal silica (organosilicon compound), and the polymerization reaction is controlled by appropriately setting the type and amount of this acid. As the acid, both inorganic acids such as hydrochloric acid, sulfuric acid and phosphoric acid; and organic acids such as formic acid and acetic acid can be used. When an inorganic acid is used, it is about 5 × 10 ^-5 to 1 × 10 ^-2 parts by weight, preferably 1 × 10 ^{-4 to} 5 × with respect to 100 parts by weight of the organosilicon compound.
It is suitable to use in a proportion of 10 ^-3 parts by weight. 1 x 10 ^-2
If the amount is more than parts by weight, the condensation rate will increase and the reaction will be difficult to control. A gel is easily formed even when the obtained paint is stored. When an organic acid is used, it is 0.07 to 4 parts by weight, preferably 0.2 per 100 parts by weight of the organosilicon compound.
Used at a rate of 2 parts by weight. When the organic silicon compound used contains an acid as an impurity or a compound which is decomposed to generate an acid, it is necessary to determine the type and amount of the acid to be used in consideration of these. is there.

The method for surface-modifying the colloidal silica with the alkoxysilane compound and / or its low condensate is as follows. The alkoxysilane compound and / or its low condensate, and colloidal silica are mixed, and a water-soluble organic solvent is added to the mixture. As the water-soluble organic solvent, alcohol-based solvent, cellosolve-based solvent, cellosolve acetate-based solvent, glyme-based solvent and the like are used. To this, appropriately add water and, if necessary, the above-mentioned acid catalyst, and add about 20 ° C or more under a temperature condition up to the reflux temperature to about
Heat for 30 minutes to about 20 hours to carry out hydrolysis condensation reaction. The amount of water to be added is such that the amount of water in the reaction system is about 0.5 to 3 mol, preferably 0.8 to 1.5 mol, per 1 mol of the alkoxy group of the alkoxysilane compound and / or its low condensation product. . If the blending ratio is less than 0.5 mol, unreacted alkoxy groups will increase. If the mixing ratio exceeds about 3 moles, polycondensation of the alkoxysilane compounds will proceed, and the resulting condensate will agglomerate, resulting in turbidity of the solution, deterioration of solution stability, and whitening during the film formation process. As a result, the appearance of the coating becomes poor and the performance deteriorates.

The reaction between the above-mentioned alkoxysilane compound and / or its low condensate and colloidal silica cannot be specified, but the alkoxy group of the alkoxysilane compound or its condensate is hydrolyzed, and the resulting silanol group is colloidal silica. It is considered that a binding reaction occurs, which reacts with silanol groups or alkoxy groups on the particle surface to form new siloxane bonds. By such a reaction, a coating film, preferably a monomolecular film, of the alkoxysilane condensate is formed on the silica particle surface of the colloidal silica. If the reaction at this time is insufficient, the colloidal silica is independently cured when the finally obtained coating material is applied and baked and cured, so that whitening and cracking of the coating film occur. On the contrary, if the reaction proceeds excessively, the condensation of the alkoxysilane compounds simultaneously proceeds, so that the silica aggregates and gels. Even if gelation does not occur during the reaction, gelation often occurs during storage.

The organopolysiloxane contained in the composition of the present invention is a condensate of an organoalkoxysilane represented by the general formula RSi (OR ') ₃ , and its polystyrene-equivalent weight average molecular weight is 500 to 10,000. In the above formula of organoalkoxysilane, R is an organic group having 1 to 8 carbon atoms, R '
Is an alkyl group having 1 to 5 carbon atoms or an acyl group having 1 to 4 carbon atoms. If the carbon number of R and R'is too large, the rate of hydrolysis in the postoperative process becomes extremely slow, and in some cases, hydrolysis hardly progresses. Examples of R include an alkyl group such as a methyl group, an ethyl group, a propyl group, and a butyl group; an aryl group such as phenyl, tolyl, and xylyl; a cycloalkyl group such as cyclohexyl;
Examples include -chloropropyl group, vinyl group, γ-glycidoxypropyl group, γ-methacryloyloxypropyl group, γ-mercaptopropyl group, γ-aminopropyl group, and 3,4-epoxycyclohexyl group. Examples of R'include a methyl group, an ethyl group, a propyl group, a butyl group and an acetyl group. Examples of such organoalkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane,
Methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, propyltrimethoxysilane, propyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-mercaptopropyltrimethoxysilane, γ
-Methacryloxytrimethoxysilane, γ-aminopropyltrimethoxysilane, 3,4-epoxycyclohexylethyltrimethoxysilane and the like. Preferably,
Methyltrimethoxysilane and / or methyltriethoxysilane are used. These organoalkoxysilanes can be used alone or in combination of two or more kinds.

The above organoalkoxysilane is hydrolyzed and polycondensed to obtain an organopolysiloxane which is a component of the composition of the present invention. To prepare the above organopolysiloxane, for example, first, the above organoalkoxysilane is prepared, and a water-soluble organic solvent is added to it.
Examples of the water-soluble organic solvent include alcohol solvents, cellosolve solvents, cellosolve acetate solvents, glyme solvents and the like. Water and, if necessary, an acid catalyst (described above) are added to this, and the hydrolysis / polycondensation reaction is performed by heating for about 30 minutes to about 20 hours under a temperature condition of about 20 ° C. or higher and the reflux temperature.

Here, hydrolysis and condensation of the organoalkoxysilane are represented by the following formula. From this equation, it is understood that the theoretical amount of water required for hydrolysis is 1.5 mol times that of the organoalkoxysilane.

_{RSi (OR ') 3 + 3H} 2 ORSi (OH) 3 + 3R'OH nRSi (OH) 3 (RSiO 1.5) n + 1.5nH 2 O In summary this equation the following equation is obtained.

nRSi amount of _{(OR ') 3 + 1.5nH 2} O (RSiO 1.5) n + 3nR'OH the water is typically about 0.5 to 3 mol per alkoxy group 1 mole of organoalkoxysilane, preferably 0.8
~ 1.5 moles. If this ratio is less than about 0.5 mol, the amount of residual alkoxy groups will increase, and the adhesion of the coating film to the substrate and the hardness will decrease. Furthermore, it is not practical because high temperature and long time are required for baking and curing the coating film. On the other hand, if the blending ratio exceeds about 3 mol, the stability of the solution deteriorates because excess water exists in the reaction solution. Such hydrolysis
The molecular weight of the product obtained by polycondensation is about 500 to about 10,
000, preferably about 500 to about 5,000. Here, the molecular weight is a value calculated by a polystyrene conversion method by gel permeation chromatography. When the molecular weight is less than about 500, the silanol content of the obtained paint is high. Therefore, when a thick coating film is formed using this paint, cracks are likely to occur. Furthermore, because of the high activity of silanol, when it is mixed with the above surface-modified colloidal silica, the polymerization reaction proceeds, gelation easily occurs, and storage stability is poor. On the other hand, when the molecular weight exceeds 10,000, the silanol content is low and the reactivity is low, and it takes a long time to form a coating film, which is not practical.

The composition of the present invention is obtained by blending the surface-modified colloidal silica and the organopolysiloxane. The blending ratio is, based on the total solid content, 30 to 90% by weight of surface-modified colloidal silica, preferably 50 to 80% by weight, 70 to 10% by weight of organopolysiloxane, preferably 50 to 20% by weight. Is the range. 10% by weight of organopolysiloxane
If it is less than 3, cracks are likely to occur in the coating film. Furthermore, since the adhesion of the coating film to the substrate is poor, it is inferior in water resistance and weather resistance. On the other hand, if it exceeds 70% by weight, it is difficult to form a thick coating film.

The composition of the present invention may further contain various additives, if necessary. For example, in addition to the above surface-modified colloidal silica and organopolysiloxane, an extender pigment or a coloring pigment may be added and used as a colored enamel, or an appropriate filler may be added to prevent corrosion, electric insulation, heat It can also be used as a paint for forming a radiation film, a conductive film, and the like. In addition to these, various surfactants, silane coupling agents, titanium coupling agents, polyamines, alkali metal salts, organometallic compounds,
Heterocyclic compounds containing nitrogen atoms, various metal alkoxides,
Examples include various conventionally known additives such as aluminum compounds such as aluminum acetylacetonate and dyes.

The coating composition for coating containing the above surface-modified colloidal silica, organopolysiloxane and, if necessary, various additives is stored or used by appropriately diluting or concentrating with an organic solvent or the like for adjusting the solid content. .

A coating film containing the composition of the present invention is applied to various base materials and cured to form a desired coating film. Substrates that can be used include metals, ceramics, cement, glass,
Examples include plastics, paper and fibers. Since the solid content in the obtained paint has sufficient performance as an inorganic binder of the paint, even if the paint containing no additive is directly applied to the surface to be coated and cured,
A relatively thick coating layer of 20 μm is formed. The coating can be cured under a relatively mild condition of about 120 to 200 ° C for 5 to 60 minutes, and it is possible to form a relatively thick coating film without cracking or peeling during curing. . The coating film obtained from the paint is transparent when it does not contain additives such as pigments, and unlike the conventional paint, the coating film does not turn white due to gelation of silica particles. In a coating material to which an extender pigment or a coloring pigment is added, it is possible to add a large amount of pigment to form a coating film having a thickness of 30 μm or more without cracking or peeling.

The composition of the present invention contains the surface-modified colloidal silica as described above and an organopolysiloxane. The surface of the silica particles of the surface-modified colloidal silica is coated with a film of a condensate of an alkoxysilane compound, and the silica particles and the coating film are bound by a stable siloxane bond. On the surface of such modified silica particles, silanol groups due to a hydrolysis reaction when modified with an alkoxysilane compound are present. Similarly, the above-mentioned organopolysiloxane also has silanol groups due to the hydrolysis reaction. By mixing both, these silanol groups react rapidly and form a condensate of silica particles and polysiloxane, resulting in a stable coating mixture. Since the silica particles are coated with the condensate of the alkoxysilane compound and the polysiloxane is present between the silica particles, the coating composition containing the composition of the present invention can be prepared by mixing the components of the coating composition like conventional coating compositions. Alternatively, the silica particles do not aggregate or gel during storage. When a coating material containing the composition of the present invention is applied to a base material and cured by heating, a uniform glossy coating film is formed on the surface of the base material. Since the silica particles are uniformly dispersed in the paint, the silica particles do not gel and cause unevenness on the coating film. Since the silica particles are firmly bound to the above-mentioned organopolysiloxane, the coating film does not shrink or crack during curing. The adhesion between the coating film and the substrate is also good.
As described above, by using the coating composition for coating of the present invention, a coating film having gloss, high hardness, and excellent heat resistance, weather resistance, chemical resistance, etc. can be formed.

(Example) Hereinafter, the present invention will be described with reference to an example. In the examples, all parts are parts by weight.

Example 1 (a) Preparation of surface-modified colloidal silica: In a reaction vessel equipped with a reflux condenser and a stirrer, 50 parts of methyltrimethoxysilane, methanol silica sol (manufactured by Nissan Chemical Industries, Ltd., solid content concentration 30) %) 330 parts, and water 15
A part was charged, heated at 60 ° C. with stirring, and reacted for about 2 hours. Then, this was cooled to room temperature to obtain surface-modified colloidal silica.

(B) Preparation of polysiloxane: 100 parts of methyltrimethoxysilane was charged into another reaction vessel equipped with a reflux condenser and a stirrer, and heated to 60 ° C while stirring. 40g of water was added to this, and at 60 ℃, about 5
After reacting for a period of time, it was cooled to room temperature and the weight average molecular weight was about
3000 organopolysiloxanes were obtained. The molecular weight was measured by a polystyrene conversion method by gel permeation chromatography.

(C) Preparation of coating composition: Surface-modified colloidal silica obtained in (a) and (b)
The coating composition A for coating was obtained by mixing with the organopolysiloxane obtained in the above item.

(D) Evaluation of coating composition for coating: The coating composition obtained in (c) was evaluated for the following items. The composition of the coating material and the obtained results are shown in Tables 1 and 2, respectively, together with the evaluation results of the coating composition for coatings obtained in Examples 2 to 5 and Comparative Examples 1 to 3 described below.
Shown in.

[Storage stability] Put the coating composition for coating in a closed container, and
After left at 3 ° C. for 3 months, the composition was examined for viscosity increase and gelation.

For the following items, the coating composition for coating was applied onto a cold-rolled stainless steel plate (JIS G4305 SUS-CP) using a spray device so that the dry coating film had a thickness of 10 μm. This was heated at 150 ° C for 30 minutes and the resulting cured coating film was evaluated.

[Appearance of coating film] The surface condition was evaluated by visual observation.

[Adhesiveness] Evaluation was made using a JIS K5400 cross pattern.

[Hardness] The pencil hardness of JIS K5400 was evaluated.

[Heat resistance] The state after placing in an oven at 400 ° C for 16 hours was observed.

[Solvent resistance] Toluene was dipped in gauze, and the coating film was rubbed 30 times, and the condition was observed.

Examples 2 to 5 Coating compositions B to E for coating were obtained by the same operation as in Example 1 with the compositions and reaction conditions shown in Table 1. The composition and the evaluation results of the obtained coating composition for coating are shown in Table 1 and Table 2, respectively.

Comparative Examples 1 to 3 A coating composition F-H for coating was obtained by the same operation as in Example 1 under the composition and reaction conditions shown in Table 1. The composition and the evaluation results of the obtained coating composition for coating are shown in Table 1 and Table 2, respectively.

Example 6 Using 100 parts of the coating composition A obtained in Example 1 as a binder,
Titanium oxide (Taipaque R-380 manufactured by Ishihara Sangyo Co., Ltd.) 3
0 part was compounded and dispersed in a sand mill for 1 hour to obtain a coating composition I for coating.

Next, the obtained coating composition I for coating was applied onto a cold-rolled stainless steel plate (JIS G4305 SUS-CP) using a spray device.
The dried coating film was applied so as to have a thickness of 30 μm and heated at 150 ° C. for 30 minutes to form a cured coating film. In addition to the evaluation items shown in Example 1, these cured coating films were evaluated for the following items. The results are shown in Examples 7 to 10 and Comparative Example 4 described later.
With the evaluation results of the coating composition for coating obtained in
It shows in Table 3.

[Gloss] The measurement was performed according to JIS H4001.

[Boiling resistance] Coated stainless steel plate in boiling water at 100 ℃ 2
The state after immersing for 4 hours was observed.

[Acid resistance] 1 ml of a 5% aqueous solution of sulfuric acid was dropped on the coating film, allowed to stand for 1 day in a petri dish with a lid, washed with water, and the state was observed.

[Alkali resistance] 1 ml of a 1% aqueous sodium hydroxide solution was dropped on the coating film, allowed to stand for 1 day in a petri dish with a lid, washed with water, and the state was observed.

[Weather resistance] 3,000 according to JIS K 5400 with a weatherometer
A 0-hour irradiation test was performed and the condition was observed.

Examples 7 to 10 Coating compositions for coating were prepared in the same manner as in Example 6 except that coating compositions B to E prepared in Examples 2 to 5 were used instead of coating composition A for coating. J to M were obtained and evaluated by the same method. The results are shown in Table 3.

Comparative Examples 4 to 6 Coating compositions for coating were prepared in the same manner as in Example 6 except that coating compositions A to H prepared in Comparative Examples 1 to 3 were used instead of coating composition A for coating. N to P were obtained and evaluated in the same manner. The results are shown in Table 3.

(Effect of the Invention) According to the present invention, as described above, a silicone-based coating composition for coating, which can easily form a coating film having excellent properties on the surface of a metal or ceramic substrate and has excellent storage stability, is provided. Provided. The coating film obtained by using the coating composition obtained by this method has high hardness, excellent scratch resistance, glossiness, and heat resistance, weather resistance, water resistance, chemical resistance, etc. Extremely excellent in In particular, it maintains high gloss even when left at high temperatures or outdoors, and does not discolor or deteriorate.
It has excellent properties not found in conventional silicone coatings. Therefore, for example, it can be advantageously used as a coating material for coating outer wall materials exposed to sunlight, equipment used under high temperature conditions, building materials that require cosmetic properties, and the like.

Claims (2)

[Claims] 1. A coating composition for coating containing surface-modified colloidal silica and organopolysiloxane, wherein the surface-modified colloidal silica has a total solid content of 30 to 90.
% By weight, and the organopolysiloxane is contained in a proportion of 70 to 10% by weight in terms of total solid content, and the surface-modified colloidal silica has 2 or more alkoxy groups (1 to 8 carbon atoms) in the molecule. Alkoxysilane compound having an atom) and / or a silica particle surface-modified with a low condensate of an alkoxysilane having two or more alkoxy groups (having 1 to 8 carbon atoms) in the molecule. Colloidal silica, wherein the surface-modified colloidal silica contains the alkoxysilane compound and / or low condensation product of alkoxysilane in an amount of 10 to 80% by weight in terms of fixed amount, and the silica particles in an amount of 90 to 20 in terms of solid amount. In a proportion by weight; and the organopolysiloxane has the general formula RSi (OR ')
₃ (where R is an organic group having 1 to 8 carbon atoms, R'is 1 to 8 carbon atoms)
5 is an alkyl group or an acyl group having 1 to 4 carbon atoms)
It is a condensate of organoalkoxysilane represented by and has a polystyrene-converted weight average molecular weight of 500 to 10,000
A coating composition for coating which is 0. 2. The surface-modified silica particles are contained in a proportion of 50 to 80% by weight in terms of total solid content, and the organopolysiloxane is contained in a proportion of 50 to 20% by weight in terms of total solid content. The coating composition for coating as described in 1.