JP5241076B2 - Forming method of coating film - Google Patents

Description

  The present invention relates to a method for forming a coating film. More specifically, the surface of an inorganic substrate is excellent in contamination resistance, weather resistance, warm water resistance (appearance and adhesion), frost damage resistance, and self-cleaning ability. It is related with the formation method of the coating film for forming the antifouling layer which has.

  In the composition in which the partially hydrolyzed condensate of silicate and / or organosilane is mixed with the top coat, the partially hydrolyzed condensate of silicate and / or organosilane migrates to the surface of the paint film during the coating film formation process, and the layers are separated. It is known to form a stain-resistant coating to form a coated coating. However, in this technique, the surface migration of the silicate and / or the partial hydrolysis condensate of organosilane to the coating surface is not sufficient, and it has led to the formation of a coating film having excellent stain resistance as required by the market. Not in.

  Therefore, a method of applying a mixture of silica sol and / or metal oxide and a small amount of an organic binder to the uppermost layer of the coating film has been developed, but the coating film has excellent stain resistance due to poor coating film forming ability. It has not yet formed.

In addition, a water-based polysiloxane or water-based sealer is applied as an undercoat on an inorganic substrate, an acrylic silicone emulsion is applied as an intermediate coating, and a water-based polysiloxane is applied as an overcoat to form a coating film on the inorganic substrate. There is a coating method that enables formation (see, for example, Patent Documents 1 and 2). The characteristic is that the adhesion with the top coating is sufficient by using an acrylic silicone emulsion paint as the intermediate coating. There is a need for improved adhesion.
JP 2002-263559 A JP 2002-263570 A

  An object of the present invention is to provide a coating film that is excellent in stain resistance, weather resistance, warm water resistance (appearance, adhesion), frost damage resistance and has a self-cleaning ability. It is in providing the formation method.

In accordance with the present invention, the inorganic substrate
(A) primer coating, or coated with (A) primer coating and (B) an intermediate paint, a step of forming a coating film,
(C) As a top coat on the coating film,
(I) 100 parts by mass of a tetraalkoxysilane represented by the general formula (1) or a partial hydrolysis-condensation product thereof,
Si (OR ¹ ) _x (OR ² ) _(4-x) (1)
Wherein, ^{R 1} and ^{R 2} is an organic group having 1 to 8 carbon atoms, ^{R 1} and ^{R 2,} be the same, may be different, x is from 0 It is an integer of 4. ]
(Ii) 20-300 parts by mass of water-dispersed colloidal silica or isopropanol-dispersed colloidal silica (in terms of solid content);
To a silica-containing condensation product obtained by hydrolytic condensation at 45 to 65 ° C.
(Iii) Water, propylene glycol monomethyl ether or dipropylene glycol monomethyl ether which is a diluent , or two or more thereof are added in an amount of 250 to 500,000 parts by mass per 100 parts by mass of the component (i). Applying a paint having a polysiloxane solution obtained as a binder and forming a top coat film;
A method of forming a coating film characterized by comprising:

  By applying the method for forming a coating film of the present invention to the surface of an inorganic base material, it is excellent in stain resistance, weather resistance, warm water resistance (appearance and adhesion), frost damage resistance, and self-cleaning ability. A coating film having an antifouling layer can be formed.

  Hereinafter, embodiments of the present invention will be described in detail.

  (A) Undercoating paint: The undercoating paint (A) used in the present invention serves to develop long-term adhesion between an inorganic base material and (B) an intermediate coating film. Examples include various solvent-based or water-based paints using styrene resin, epoxy / polyamine resin, urethane resin and the like as binders.

  (B) Intermediate coating: The intermediate coating (B) used in the present invention serves to develop long-term adhesion to both the undercoat (A) and the topcoat (C). It is possible to use a paint generally used as a top coat.

  Specific examples include solvent-based or water-based paints using an acrylic resin, an acrylic urethane resin, a urethane resin, a fluororesin, an organic-inorganic composite resin, or the like as a binder.

  (C) Preferably, the compound having an Si-OR group (R is a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms) in the lower layer of the top coat film is 0.1 to 50 mass in terms of a film-forming component. It is desirable to use a coating material containing 1% because of better adhesion to the (C) top coat film.

  As a paint containing a compound having a Si-OR group (R is a hydrogen atom or a hydrocarbon group having 1 to 12 carbon atoms), a hydrolyzable silyl group-containing vinyl paint, an organopolysiloxane paint, Examples include silane coupling agent-added paints.

In order to impart various functions, the intermediate coating (B) used in the present invention contains an antifungal agent, an antiseptic, an ultraviolet absorber, a light stabilizer, an extender pigment, a coloring pigment, and an antirust pigment. When blended, it is preferable to blend various additives such as a dispersant, an anti-settling agent, and a thickener.
(C) Top coat: The top coat (C) used in the present invention comprises (i) a tetraalkoxysilane represented by the general formula (1) or a partially hydrolyzed condensate thereof, (ii) colloidal silica, (Iii) A polysiloxane solution obtained by adding either or both of water and an organic solvent as a diluent to a silica-containing condensation product obtained by hydrolytic condensation of.

  Below, each structural component of the binder in this invention is demonstrated.

(I) Component (i) The component is a tetraalkoxysilane represented by the general formula (1) or a partially hydrolyzed condensate thereof.

Si (OR ¹ ) _x (OR ² ) _(4-x) (1)
Wherein, ^{R 1} and ^{R 2} is an organic group having 1 to 8 carbon atoms, x is an integer of 0-4. ]

In the above formula, preferred examples of the organic group as R ¹ and R ² include an alkyl group, a cycloalkyl group, and an aryl group. R ¹ and R ² may be the same or different.

  Here, the alkyl group may be linear or branched. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, Examples thereof include alkyl groups such as heptyl group and octyl group. A preferable alkyl group is an alkyl group having 1 to 4 carbon atoms.

  Preferred examples of the cycloalkyl group include a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, and the like.

  Examples of the aryl group include a phenyl group.

  Specific examples of the tetraalkoxysilane represented by the above formula (1) include, for example, tetramethoxysilane, tetraethoxysilane, tetrabutoxysilane, and triethoxybutoxysilane. These tetraalkoxysilanes can be used alone or as a mixture of two or more.

The component (i) may be the partially hydrolyzed condensate of tetraalkoxysilane described above. The polystyrene-converted weight average molecular weight of the condensate is preferably from 300 to 5,000, and particularly preferably from 500 to 3,000. By using a condensate having such a molecular weight, the adhesiveness is reduced without deteriorating storage stability. A good coating film can be obtained. Moreover, the partial hydrolysis-condensation product of tetraalkoxysilane is suitable to have one or more, preferably 3 to 30, —OH groups, —OR ¹ groups, or —OR ² groups bonded to silicon atoms.

  Specific examples of such condensates include commercially available products such as ethyl silicate 40 and ethyl silicate 56 (both manufactured by Colcoat).

Component (ii) As the component (ii) colloidal silica, silica particles dispersed in water or an organic solvent are preferably used. Colloidal silica is usually a type in which approximately spherical silica particles having an average particle diameter of 5 to 100 nm, preferably 10 to 30 nm are dispersed, and the silica particles are chained to have a thickness of about 5 to 50 nm and a length of about 40 to 400 nm. There are a type in which the particles are aggregated and dispersed in a solution, a type in which silica particles having an average particle diameter of 5 to 50 nm are aggregated in a ring and dispersed in the solution, and the like. Also, different types can be mixed and used.

  Silica particles in which approximately spherical silica particles are dispersed in water can be easily obtained as a commercial product. Such colloidal silica is, for example, SNOWTEX-20, SNOWTEX manufactured by Nissan Chemical Industries, Ltd. Preferred examples include -O, Snowtex-C, Snowtex-S, and Adelite AT-20, AT-20N, AT-20A, AT-300 manufactured by Asahi Denka Kogyo Co., Ltd.

  Colloidal silica in which almost spherical silica particles are dispersed in an organic solvent is, for example, lower alcohols such as methanol, ethanol, isopropanol, n-butanol, isobutanol; ethylene glycol, ethylene glycol monobutyl ether, ethylene glycol monoacetate. Ethylene glycol derivatives such as ethyl ether; diethylene glycol derivatives such as diethylene glycol and diethylene glycol monobutyl ether; ketones such as acetone and methyl ethyl ketone; and silica particles dispersed in organic solvents such as toluene, xylene, ethyl acetate, and butyl acetate This organic solvent-dispersed colloidal silica can also be easily obtained as a commercial product. For example, Snowtex MA-ST-M, I manufactured by Nissan Chemical Industries, Ltd. A-ST, EG-ST, EG-ST-ZL can be preferably used.

  The chain colloidal silica is dispersed in water or the above-mentioned organic solvent, and can be easily obtained as a commercial product. Specific examples thereof include, for example, Snowtex-UP manufactured by Nissan Chemical Industries, Ltd. SNOWTEX-OUP (above, water dispersion), SNOWTEX MA-ST-UP, IPA-ST-UP (above, organic solvent dispersion) and the like are preferable.

  Examples of the commercially available cyclic colloidal silica include SNOWTEX-PS-SO, SNOWTEX-PS-M, SNOWTEX-PS-L and the like manufactured by Nissan Chemical Industries, Ltd.

  The component (ii) is used to improve the curability and stain resistance of the coating film, and the blending amount is 10 to 500 parts by mass in terms of solid content with respect to 100 parts by mass of the component (i). Yes, preferably 20 to 300 parts by mass is appropriate. (Ii) If the blending amount of the component is less than the above range, the effect of improving the curability and stain resistance of the coating film is small, and conversely if too large, the mixing stability, the crack resistance of the coating film, etc. Tend to decrease.

  (Ii) The pH of the component colloidal silica dispersion is preferably 6 or less, and more preferably 3 to 5. If the pH of the colloidal silica dispersion is greater than 6, the storage stability of the resulting polysiloxane solution tends to be insufficient.

  In the reaction between the component (i) and the component (ii), if the component (ii) is dispersed in water, the hydrolysis condensation reaction can be performed using the water in the component (ii). . On the other hand, when the component (ii) is dispersed in an organic solvent, the hydrolysis condensation reaction can be performed by adding water in which the component (i) can be hydrolyzed by 50% or more. Moreover, it is preferable to add acetic acid, acids, such as hydrochloric acid, nitric acid, formic acid, or basic compounds, such as ammonia and an amine compound, as a catalyst for promoting reaction.

  The hydrolysis or partial condensation reaction is usually carried out at 40 to 80 ° C., preferably 45 to 65 ° C., for example, for 2 to 15 hours. In the presence of a catalyst, the reaction may be carried out at room temperature. Is possible.

  (Iii) Component To the silica-containing condensation product of component (i) and component (ii) obtained as described above, (iii) Add one or both of water and organic solvent as a diluent. Thus, a polysiloxane solution is obtained.

  (Iii) As water used as a diluent, pure water, distilled water, ion exchange water, tap water, or the like can be used.

  Examples of the organic solvent include alcohols such as methanol, ethanol, propanol, and butanol, alcohol ethers such as ethylene glycol monoethyl ether and ethylene glycol monobutyl ether, and hydrophilic organic solvents such as ketones such as acetone and methyl ethyl ketone, It is possible to use a mixed organic solvent such as toluene, xylene, ethyl acetate, butyl acetate and other hydrophobic organic solvents for paints.

  (Iii) The compounding quantity of a component is 250-500000 mass parts per 100 mass parts of (i) component, Preferably, 500-100000 mass parts is suitable. When the blending amount of the component (iii) is less than the above range, a uniform coating film is difficult to obtain, and conversely when it is too much, the stability of the obtained polysiloxane solution tends to be inferior.

  Among organic solvents, in particular, alcohols soluble in water are preferable in order to prevent the stability of the paint and lifting of the undercoat film. For example, lower alcohols such as methanol, ethanol, and propanol, particularly the general formula (2) It is preferable to contain the organic solvent shown by 1-5 mass% in (C) top coat composition.

HO— (CHR ³ CH ₂ O) _n R ⁴ (2)
[Wherein R ³ is a methyl group or a hydrogen atom, R ⁴ is an alkyl group having 1 to 8 carbon atoms, and n is 1 or 2. ]

In R ^4, the alkyl group having 1 to 8 carbon atoms may be linear or branched. Examples of the alkyl group include methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, pentyl group, hexyl group, Examples thereof include alkyl groups such as heptyl group and octyl group. Preferably it is a C1-C4 alkyl group.

  Examples of the organic solvent of the general formula (2) include ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, and dipropylene glycol monomethyl. Preferred examples include ether and dipropylene glycol monoethyl ether. These can be used alone or in combination.

  About (iv) Component As needed, as (iv) component, the surfactant from which the surface tension of 0.01 mass% aqueous solution becomes 40 dyn / cm (25 degreeC) or less can be used. The component (iv) is blended in an amount of 0.001 to 3% by mass in terms of solid content in the above (C) top coating composition for the purpose of improving the coating film appearance of the polysiloxane solution obtained as described above. Is preferred. In addition, when the amount exceeding 3% by mass is used, the appearance of the coating film and the water resistance of the coating film tend to be inferior. If the surface tension of the aqueous solution having a concentration of component (iv) of 0.01% by mass is larger than 40 dyn / cm, a uniform coating film cannot be obtained, and an uneven coating film appearance tends to be obtained.

  (Iv) As the surfactant, for example, an anionic or nonionic surfactant can be used. Specific examples thereof include, for example, Neugen ET-143, ET-135 (Daiichi Kogyo Seiyaku Co., Ltd.), Perex NB-L (Kao Co., Ltd.), Florard FC4430 (Sumitomo 3M Co., Ltd.) Polyflow KL-600 (manufactured by Kyoei Chemical Co., Ltd.), Surflon S-111, S-141 (manufactured by Seimi Chemical Co., Ltd.) and the like are preferred, and a fluorine-based surfactant is particularly preferred.

  The (C) top coat thus obtained has a heating residue after drying at 150 ° C. for 30 minutes, usually 0.01 to 40% by mass. (C) The heating residue of the top coat is preferably 0.1 to 10% by mass.

  The surface tension of the (C) top coat used in the present invention is preferably 50 dyn / cm (25 ° C.) or less, more preferably 45 to 15 dyn / cm (25 ° C.), and 50 dyn / cm (25 ° C.). If it is larger than that, it is difficult to form a uniform coating film, and sufficient coating film performance cannot be exhibited.

  The (C) topcoat used in the present invention contains a polysiloxane solution comprising the hydrolysis condensation reaction product of the components (i) and (ii) described above and (iii) a diluent. Furthermore, if necessary, for the purpose of improving the coating film properties and coloring, fillers, dyes, curing agents, and further various additives such as curing accelerators, thickeners, pigment dispersants, etc. You may mix | blend.

  As the filler, for example, various pigment extender pigments such as talc, barium carbonate, calcium carbonate, barium sulfate, bentonite, titanium oxide, carbon black, Bengala, and lithopone, and colored pigments can be used. The blending amount of the filler is preferably 0 to 70% by mass, and particularly preferably 0 to 50% by mass in the solid content of the coating composition.

  Examples of the curing agent include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl)- γ-aminopropylmethyldimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldiethoxysilane, N-cyclohexyl-γ-aminopropyltrimethoxysilane, N-cyclohexyl-γ-aminopropyltriethoxy Having an amino group in the molecule such as silane, γ- (2-aminoethyl) -aminopropyltrimethoxysilane, γ- (2-aminoethyl) -aminopropylmethyldimethoxysilane, γ-anilinopropyltrimethoxysilane, Alkoxysilane capable of hydrolytic condensation reaction and γ-glycidoxypropyl Trimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriisopropenyloxysilane, γ- Hydrolysis condensation reaction having an epoxy group such as an adduct of glycidoxypropyltriiminooxysilane, β- (3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, γ-isocyanatopropyltriisopropenyloxysilane and glycidol Possible alkoxysilanes and the like are mentioned.

  Typical examples of the curing accelerator include organic tin compounds such as tin octylate, dibutyltin dilaurate, dibutyltin dimaleate, and tributyltin laurate, and amine compounds such as ethylenediamine, diethylenetriamine, piperidine, phenylenediamine, and triethylamine. In particular, organotin compounds are effective.

  Examples of the inorganic base material to be coated include inorganic ceramic base materials and metal base materials such as concrete, iron, and aluminum.

<Formation method of coating film>
In the present invention, the coating means for the (A) primer coating on the surface of the inorganic base material may form a coating film having a dry film thickness of 5 to 60 μm by a single application with a brush, spray, roll coater, flow coater or the like. It is possible to form a coating film by drying at room temperature or by heating at 30 to 150 ° C. for 1 to 60 minutes and drying.

  (B) The coating means of the intermediate coating is a brush, spray, roll coater, flow coater, screen printing, gravure printing, dipping, etc., with a single coating and a dry film thickness of 5-50 μm, and 2-3 coatings of 10 A 300 μm coating film can be formed, and it is possible to form a coating film by drying at room temperature or heating at 30 to 150 ° C. for 1 to 60 minutes and drying.

  (C) The coating means of the top coat can form a dry film thickness of 1 to 50 μm by a single application and a coating of 2 to 100 μm by a second application by brush, spray, roll coater, flow coater, etc. It is possible to form a coating film by drying at room temperature or by heating at 30 to 150 ° C. for 1 to 60 minutes and drying.

  Hereinafter, the present invention will be described in more detail with reference to examples. In the examples, “parts” and “%” are expressed on a mass basis unless otherwise specified.

  "Production Example 1" A reactor equipped with a reflux condenser and a stirrer was charged with 200 parts of methanol, then (i) 100 parts of tetraethoxysilane, and (ii) isopropanol-dispersed colloidal silica (Nissan Chemical Industry ( Co., Ltd., IPA-ST; solid content 30%, pH 3.2) 230 parts were added and mixed, and then a mixture of 250 parts of ion-exchanged water and 6 parts of 0.1N hydrochloric acid aqueous solution was stirred. In addition, after reacting at 60 ° C. for 3 hours, (iii) 1200 parts of ion exchange water was added and cooled to room temperature to obtain a polysiloxane solution A (solid content 5%) having a surface tension of 25 dyn / cm.

  "Production Example 2" A reactor equipped with a reflux condenser and a stirrer was charged with 200 parts of methanol, then (i) 100 parts of tetramethoxysilane, and (ii) isopropanol-dispersed colloidal silica (Nissan Chemical Industry ( Co., Ltd., IPA-ST; solid content 30%, pH 3.2) 100 parts were added and mixed, and then a mixture of 250 parts of ion-exchanged water and 6 parts of 0.1N aqueous hydrochloric acid was added with stirring. After reacting at 60 ° C. for 3 hours, (iii) 750 parts of ion-exchanged water was added and cooled to room temperature to obtain a polysiloxane solution B (solid content 5%) having a surface tension of 26 dyn / cm.

  “Production Example 3” In a reactor equipped with a reflux condenser and a stirrer, (i) 100 parts of tetraethoxysilane was added, and then (ii) water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, Ltd., Snow After adding and mixing 150 parts of Tex-O; solid content 20%, pH 3.8), a mixture of 250 parts of ion-exchanged water and 6 parts of 0.1N hydrochloric acid aqueous solution was added with stirring. After reacting for 3 hours, (iii) 70 parts of propylene glycol monomethyl ether and 600 parts of ion-exchanged water were added and cooled to room temperature to obtain a polysiloxane solution C (solid content 5%) having a surface tension of 45 dyn / cm.

  "Production Example 4" A reactor equipped with a reflux condenser and a stirrer was charged with 200 parts of methanol, then (i) 100 parts of tetraethoxysilane, and (ii) water-dispersed colloidal silica (Nissan Chemical Industries ( Co., Ltd., Snowtex-O; solid content 20%, pH 3.8) 500 parts were added and mixed, and then a mixture of 250 parts of ion-exchanged water and 6 parts of 0.1N hydrochloric acid aqueous solution was stirred. In addition, after reacting at 60 ° C. for 3 hours, (iii) 100 parts of dipropylene glycol monomethyl ether and 1700 parts of ion-exchanged water were added, cooled to room temperature, and a polysiloxane solution D (solid content of 5 %).

  "Production Example 5" A reactor equipped with a reflux condenser and a stirrer was charged with 200 parts of methanol, then (i) 100 parts of tetraethoxysilane, and (ii) isopropanol-dispersed colloidal silica (Nissan Chemical Industries ( Co., Ltd., IPA-ST; solid content 30%, pH 3.2) After adding 1000 parts and mixing, with stirring, a mixture of 250 parts of ion-exchanged water and 6 parts of 0.1N aqueous hydrochloric acid was added. After reacting at 60 ° C. for 3 hours, (iii) 65,000 parts of ion exchange water was added and cooled to room temperature to obtain a polysiloxane solution E (solid content 0.5%) having a surface tension of 32 dyn / cm.

  "Production Example 6" In a reactor equipped with a reflux condenser and a stirrer, 100 parts of methanol was added, and then (i) 100 parts of tetraethoxysilane was added and mixed, and then the ion-exchanged water was stirred. After adding a mixed solution of 36 parts and 2.5 parts of 0.1N aqueous hydrochloric acid and reacting at 60 ° C. for 3 hours, (iii) adding 450 parts of ion-exchanged water, cooling to room temperature, and surface tension of 30 dyn / cm polysiloxane solution F (solid content 5.2%) was obtained.

  “Production Example 7” 50 parts of methanol was put into a reactor equipped with a reflux condenser and a stirrer, and then (ii) water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, Ltd., Snowtex-O; solid content) 20 parts, 20%, pH 3.8) 50 parts were added and mixed, then, with stirring, (iii) 100 parts of ion-exchanged water was added and stirred at room temperature for 3 hours to obtain a silica dispersion solution G (solid) with a surface tension of 70 dyn / cm. 5%).

  “Production Example 8” In a reactor equipped with a reflux condenser and a stirrer, 78 parts of ion-exchanged water was added, and then (ii) water-dispersed colloidal silica (manufactured by Nissan Chemical Industries, Snowtex-O; (20) Solid content 20%, pH 3.8) After adding and mixing, 20 parts, while stirring, (i) 2 parts of tetraethoxysilane was added and stirred at room temperature for 3 hours to obtain a silica mixed solution H having a surface tension of 37 dyn / cm. (Solid content 4.7%) was obtained.

"Film performance evaluation test"
(Preparation of coating performance test board 1)
A gypsum slag perlite plate (thickness 12 mm) is used as an inorganic material (inorganic base material), and a polyisocyanate prepolymer solution sealer “V-Selan # 100 sealer” (Dainippon Paint Co., Ltd., butyl acetate) is used as an undercoat on the surface. : Xylene = 100% diluted with a solvent of 1: 1) was spray-coated with a spray so that the coating amount was 90 to 100 g / m ² (wet mass). This was dried at 100 ° C. for 5 minutes. Next, an acrylic silicone resin-based paint “V-Selan # 500 enamel” (Dainippon Paint Co., Ltd., 40% diluted with a solvent of butyl acetate: xylene = 1: 1) is applied as an intermediate coating. Spray coating was performed so that the film thickness was 90 g / m ² (wet mass) and the film thickness was 40 μm. This was dried at 120 ° C. for 12 minutes to obtain a test plate (I). As the intermediate coating film, the amount of the Si-OR group-containing compound (R is a methyl group) was 1.5% by mass in terms of a coating film forming component.

(Preparation of coating film performance test plate 2)
A gypsum slag perlite plate (thickness 12 mm) is used as an inorganic material (inorganic base material), and a polyisocyanate prepolymer solution sealer “V-Selan # 100 sealer” (Dainippon Paint Co., Ltd., butyl acetate) is used as an undercoat on the surface. : Xylene = 100% diluted with a solvent of 1: 1) was spray-coated with a spray so that the coating amount was 90 to 100 g / m ² (wet mass). This was dried at 100 ° C. for 5 minutes. Next, an acrylic emulsion resin-based paint “V Seran # 300 Enamel” (manufactured by Dainippon Paint Co., Ltd.) is applied as an intermediate coating so that the coating amount is 80 to 90 g / m ² (wet mass) and the film thickness is 40 μm. Spray painted with spray. This was dried at 100 ° C. for 15 minutes to obtain a test plate (B).

Next, top coating materials were prepared on test plates (A) and (B) with the formulation shown in Table 1, and sprayed so that the coating amount was 70 to 80 g / m ² (wet mass) and the film thickness was 15 μm. Painted. This was dried at 70 ° C. for 10 minutes, and then dried at room temperature for 3 days. The resulting coating film was tested for appearance, warm water resistance, stain resistance, weather resistance, and frost damage resistance. It was shown in 1.

  The surface tension and heating residue of the top coat were measured as follows.

<Method for measuring surface tension>
The surface tension was measured at 25 ° C. using a surface tension meter (CBUP-A5 type) manufactured by Kyowa Interface Science Co., Ltd.

<Measurement method of heating residue>
The heating residue is precisely weighed about 3 grams of the top coating in an aluminum cup, weighed after drying for 30 minutes using an oven at 150 ° C, and calculated from the mass of the residue relative to the original weight. (%) Was calculated.

  In addition, the test method and evaluation criteria were performed based on the following.

<Appearance of coating film>
The appearance of the coating film before the test was visually evaluated as follows.
○… Good (transparent film)
×… Bad (cloudy film)

<Hot water resistance: Appearance>
The appearance of the coating film after the coated plate produced as described above was immersed in warm water at 80 ° C. for 3 hours was visually judged as follows during the immersion and after the coating film was dried.
◎ ... No change during soaking and after drying coating ○: Slight whitening during soaking, but no change after drying coating △ ... Whitening during soaking, loss of gloss after drying coating, whitening, etc. X ... Slightly whitening during soaking, and significant changes such as loss of gloss and whitening after drying the film

<Hot water resistance: adhesion>
After dipping the coated plate in warm water at 80 ° C. for 3 hours, using a cutter knife on the coated film of the removed coated plate, make 25 gobangs at intervals of 2 mm, apply cellophane adhesive tape, peel off, The number of eyes without film peeling was counted.

<Contamination resistance>
24 hours after drawing with red and black magic inks on the coated plate, it was wiped off with a cloth moistened with n-butanol, and its decontamination property was visually judged as follows.
◎… Complete removal ○… Slightly slight contamination △… Slight contamination ×… Severe contamination

<Weather resistance>
The weather resistance was determined as follows using a sunshine weather-ometer for 3000 hours.
○: No change in coating film appearance, gloss retention of 95% or more Δ: Minor change in coating film appearance, gloss retention of 80-94%
X: Significant change in coating film appearance, gloss retention less than 80%

<Frost resistance>
The frost damage resistance of 40 cycles was measured by ASTM-C666A method, and visually judged as follows.
◎… No occurrence of cracks ○… Generation of very slight cracks △… Occurrence of cracks or partial peeling of coating film ×… Significant cracking or peeling of coating film

１）アニオン系界面活性剤「ペレックスＮＢ−Ｌ」（花王（株）製）、有効成分３５質量％、表面張力３８ｄｙｎ／ｃｍ（２５℃、０．０１質量％水溶液）
表１より明らかな通り、ポリシロキサン溶液Ａ〜Ｅを含有する塗料組成物を使用した実施例１〜７は、優れた塗膜性能を有していた。

1) Anionic surfactant “Perex NB-L” (manufactured by Kao Corporation), active ingredient 35 mass%, surface tension 38 dyn / cm (25 ° C., 0.01 mass% aqueous solution)
As is clear from Table 1, Examples 1 to 7 using the coating composition containing the polysiloxane solutions A to E had excellent coating performance.

  On the other hand, in the paint using the polysiloxane solution F not subjected to the condensation reaction with the component (ii) of Comparative Example 1, the stain resistance, weather resistance and frost damage resistance were poor. In the paint using the silica dispersion solution G not subjected to the condensation reaction with the component (i) of Comparative Example 2, the coating film appearance, warm water resistance (appearance, adhesion), weather resistance and frost damage resistance were very poor. In addition, in the paint using the silica mixed solution H obtained by simply mixing the components (i) and (ii) of Comparative Example 3, the coating film appearance, warm water resistance (appearance, adhesion), and contamination resistance are very poor. It was.

  The method for forming a coating film of the present invention is useful as a means for forming a coating film excellent in stain resistance, weather resistance, warm water resistance (appearance and adhesion), and frost damage resistance on the surface of an inorganic substrate. is there.

Claims (2)

Inorganic substrate
(A) primer coating, or coated with (A) primer coating and (B) an intermediate paint, a step of forming a coating film,
(C) As a top coat on the coating film,
(I) 100 parts by mass of a tetraalkoxysilane represented by the general formula (1) or a partial hydrolysis-condensation product thereof,
Si (OR ¹ ) _x (OR ² ) _(4-x) (1)
Wherein, ^{R 1} and ^{R 2} is an organic group having 1 to 8 carbon atoms, ^{R 1} and ^{R 2,} be the same, may be different, x is from 0 It is an integer of 4. ]
(Ii) 20-300 parts by mass of water-dispersed colloidal silica or isopropanol-dispersed colloidal silica (in terms of solid content);
To a silica-containing condensation product obtained by hydrolytic condensation at 45 to 65 ° C.
(Iii) Water, propylene glycol monomethyl ether or dipropylene glycol monomethyl ether which is a diluent , or two or more thereof are added in an amount of 250 to 500,000 parts by mass per 100 parts by mass of the component (i). Applying a paint having a polysiloxane solution obtained as a binder and forming a top coat film;
A method for forming a coating film, comprising:
Further, as the component (iv), a surfactant having a surface tension of an aqueous solution having a concentration of 0.01% by mass of 40 dyn / cm (25 ° C.) or less is added in an amount of 0.001 to 3% by mass (solid) The method for forming a coating film according to claim 1, which is contained in terms of minute).