Coating method

Abstract

To provide a coating method which can form a coating film that has sufficient stain resistance and excellent weathering resistance and followability.SOLUTION: There is provided a coating method for coating a top coating material to a coated surface having a joint part, wherein the top coating material contains a main agent and a curing agent, the main agent contains a hydroxyl group-containing resin (A), the curing agent contains a polyisocyanate compound (B) and a silicate compound (C), a hydroxyl group-containing resin (As) containing a silicone component and other hydroxyl group-containing resin (At) are contained as the hydroxyl group-containing resin (A), and the hydroxyl value of the hydroxyl group-containing resin (As) containing the silicone component is larger than the hydroxyl value of the other hydroxyl group-containing resin (At).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a coating method. [Background technology]

[0002] The walls of buildings are formed by joining together base materials such as lightweight concrete panels, aerated concrete panels, siding boards, etc. In this case, the joints (joints) between the base materials are filled with a sealant or the like, and are designed to be easily displaced so as to withstand changes in temperature, humidity, etc. On the other hand, sealants tend to remain sticky (tacky) on exposed surfaces, which can lead to the adhesion of contaminants such as dirt and dust over time, damaging the appearance. Furthermore, exposed sealants are prone to deterioration, which can lead to problems.

[0003] Various methods for preventing such contamination of sealants have been disclosed. For example, Japanese Patent Laid-Open Publication No. 7-82548 (Patent Document 1) discloses a method for preventing contamination of the surface of a sealant by coating the surface of the sealant with an inorganic coating material containing a hydrolysis condensate of organoalkoxysilane, colloidal silica, or the like.

[0004] [Patent Document 1] Japanese Patent Application Publication No. 7-82548 DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0005] However, inorganic coating materials such as those described in the above-mentioned patent documents usually form coating films with extremely high hardness, which makes it difficult for them to follow the movement of the sealing material, and there is a risk of cracks occurring in the coating film.

[0006] The present invention has been made in consideration of the above-mentioned points, and has as its object to provide a coating method capable of forming a coating film having sufficient stain resistance as well as excellent weather resistance and conformability. [Means for solving the problem]

[0007] In order to solve such problems, the present inventors have intensively studied and come up with a coating method for applying a topcoat material containing a specific resin component as an essential component, and have completed the present invention.

[0008] That is, the present invention has the following features. 1. A coating method for applying a topcoat material to a surface having a joint, The above-mentioned topcoat material has a base agent and a hardener, The base material contains a hydroxyl group-containing resin (A), The curing agent contains a polyisocyanate compound (B) and a silicate compound (C), The hydroxyl-containing resin (A) includes a hydroxyl-containing resin (As) containing a silicone component and another hydroxyl-containing resin (At), A coating method characterized in that the hydroxyl value of the silicone-containing hydroxyl-containing resin (As) is greater than the hydroxyl value of the other hydroxyl-containing resins (At). 2. The coating method according to 1, wherein the hydroxyl-containing resin (As) containing a silicone component is a non-aqueous dispersion type resin (a1). 3. The coating method according to claim 1 or 2, characterized in that the polyisocyanate compound (B) includes a polyisocyanate compound (b1) having an isocyanate group content of less than 14 mass% and a polyisocyanate compound (b2) having an isocyanate group content of 14 mass% or more. Effect of the Invention

[0009] According to the coating method of the present invention, it is possible to form a coating film which has sufficient stain resistance, as well as excellent weather resistance and conformability to the substrate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described.

[0011] The coating method of the present invention is to apply a topcoat material to a coating surface (wall surface, etc.) having a joint part to form a topcoat layer. If necessary, a primer material can be applied to a coating surface (wall surface, etc.) having a joint part to form a primer layer, and then a topcoat material can be applied.

[0012] A coating surface with joints is a coating surface in which multiple plate-shaped wall materials are joined together using a joint material such as a sealant. Such coating surfaces are designed to withstand changes in temperature, humidity, etc., by using the joint material at the joints between the plate-shaped wall materials, and are generally used in buildings such as detached houses, apartment buildings, stores, and various public facilities.

[0013] Such a plate-like wall material is not particularly limited, and known materials can be used, for example, cement board, extrusion molding board, slate board, PC board, ALC board, fiber reinforced cement board, metal siding board, ceramic siding board, ceramic board, calcium silicate board, gypsum board, plastic board, hard wood chip cement board, PVC extrusion siding board, plywood, etc. The plate-like wall material may have an existing coating film (old coating film) or the like on its surface.

[0014] The surface shape of the plate-shaped wall material may be, for example, flat, uneven, etc. Among these, examples of the uneven surface shape include a tile pattern, a brick pattern, a geometric pattern, a striped pattern, a lattice pattern, a polka dot pattern, a sand wall pattern, a citron skin pattern, a ripple pattern, etc., as well as a graphic pattern designed with animals and plants, etc.

[0015] In the present invention, a plurality of plate-like wall materials are arranged side by side via joints. That is, joints are provided between the plate-like wall materials. The width of the joints is preferably about 3 to 20 mm (more preferably 5 to 15 mm). The joints are filled with a joint material such as a sealant or a dry joint material. In the present invention, "α to β" is synonymous with "α or more and β or less."

[0016] As the sealant, a general one can be used, for example, a silicone-based sealant, a modified silicone-based sealant, a polysulfide-based sealant, a modified polysulfide-based sealant, an acrylic urethane-based sealant, a polyurethane-based sealant, an SBR-based sealant, a butyl rubber-based sealant, etc. These sealants may be of either one-component type or two-component type, etc. The method for filling the sealant is not particularly limited, and for example, a known method using a gun or spatula can be used.

[0017] Before filling with the sealant, a backup material may be filled or a primer may be applied. As the backup material, for example, a foamed polyethylene backup material may be used. As the primer, for example, a synthetic rubber primer, an acrylic primer, a urethane primer, an epoxy primer, a silicone resin primer, a silane primer, etc. may be used.

[0018] If necessary, a primer can be applied to the surface to be coated that has such joints. As such a primer, a known material can be used, and for example, a material having at least one function selected from adhesion, water resistance, substrate reinforcement, concealment, substrate adjustment, substrate followability, etc. can be used. As such a primer, for example, a sealer, a primer, a surfacer, etc. can be mentioned.

[0019] The undercoat material contains a binder as an essential component, and if necessary, contains color pigments and other additives. Among these, as the binder, for example, various binders such as water-soluble resin, water-dispersible resin (resin emulsion), solvent-soluble resin, solventless resin, non-water-dispersible resin, powder resin, or a composite binder of these can be used. These may have crosslinking reactivity. In addition, the form of the binder is not particularly limited, and may be either one-liquid type or two-liquid type. Examples of the types of resin that can be used include vinyl acetate resin, vinyl chloride resin, epoxy resin, silicone resin, acrylic resin, urethane resin, acrylic silicone resin, etc., or composite resins thereof. Among these, one or more types selected from epoxy resin, acrylic resin, acrylic silicone resin, or composite resins thereof are suitable.

[0020] The undercoat material can be applied by a known method, such as spray coating, roller coating, brush coating, etc. The undercoat material can be applied to the entire surface of the surface to be coated, including the joints, or only to the plate-shaped wall material excluding the joints. After the undercoat material is applied to the entire surface of the surface to be coated, including the joints, it can be removed. The appropriate mode can be selected according to the type of undercoat material used.

[0021] The amount of the undercoat applied may be selected appropriately, but is preferably 0.05 to 1 kg / m 2 When applied, the viscosity can be adjusted appropriately by diluting with water, a solvent, or the like. The dilution ratio is preferably 0 to 20% by mass. The viscosity of the primer when applied (viscosity at 20 rpm (point value at the fourth rotation) measured by a BH type viscometer, measurement temperature 23°C. If the primer is diluted, the viscosity after dilution) is preferably 4 Pa·s or less, more preferably 0.01 to 3 Pa·s, and even more preferably 0.1 to 2 Pa·s.

[0022] The topcoat material of the present invention has a base agent and a curing agent, the base agent contains a hydroxyl group-containing resin (A), and the curing agent contains a polyisocyanate compound (B) and a silicate compound (C).

[0023] (Main ingredient) The base material contains a hydroxyl-containing resin (A) (hereinafter also referred to as "component (A)"). The component (A) contains a hydroxyl-containing resin (As) containing a silicone component and another hydroxyl-containing resin (At), and the hydroxyl value of the hydroxyl-containing resin (As) containing a silicone component is greater than that of the other hydroxyl-containing resin (At). In such a case, the crosslink density of the coating film is increased, and excellent effects can be exhibited in terms of weather resistance, stain resistance, followability, etc. This mechanism of action is not limited, but by including another hydroxyl-containing resin (At) which has a slightly milder crosslinking reaction than the hydroxyl-containing resin (As) containing a silicone component, the distribution of hydroxyl groups in the coating film becomes uniform, and the crosslinking reaction is less likely to be biased. It is presumed that this results in the formation of a coating film with a high crosslink density and improved weather resistance, stain resistance, followability, etc. In the present invention, component (A) that contains a silicone component as a constituent is referred to as the “hydroxyl-containing resin (As) containing a silicone component” (hereinafter also referred to as the “component (As)”), and component (A) that does not contain a silicone component as a constituent is referred to as the “other hydroxyl-containing resin (At)” (hereinafter also referred to as the “component (At)”).

[0024] The component (A) of the present invention may be any resin containing a hydroxyl group, such as polyether polyol, polyester polyol, acrylic polyol, fluorine-containing polyol, etc., and may also be used, such as phenol resin polyol, epoxy polyol, polybutadiene polyol, polyisoprene polyol, polyester-polyether polyol, urea-dispersed polyol, carbonate polyol, etc. One or more of these may be used as the component (A). It is particularly preferable that the component (A) of the present invention contains an acrylic polyol.

[0025] The acrylic polyol may be a copolymer of a hydroxyl group-containing monomer, an alkyl (meth)acrylate ester, and, if necessary, other monomers. Examples of hydroxyl group-containing monomers include hydroxyalkyl esters of (meth)acrylic acid, such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; hydroxyalkyl vinyl ethers, such as hydroxyethyl vinyl ether, hydroxypropyl vinyl ether, hydroxybutyl vinyl ether, and hydroxypentyl vinyl ether; and hydroxyallyl ethers, such as ethylene glycol monoallyl ether, diethylene glycol monoallyl ether, and triethylene glycol monoallyl ether. One or more of these can be used.

[0026] Examples of (meth)acrylic acid alkyl esters include methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, cyclohexyl (meth)acrylate, and the like. One or more of these can be used.

[0027] Examples of other monomers include amino group-containing monomers such as dimethylaminoethyl (meth)acrylate, dimethylaminopropyl (meth)acrylate, dimethylamino (meth)acrylate, aminoethyl (meth)acrylate, and diethylaminoethyl (meth)acrylate; carboxyl group-containing monomers such as acrylic acid, methacrylic acid, crotonic acid, maleic acid or its monoalkyl ester, itaconic acid or its monoalkyl ester, and fumaric acid or its monoalkyl ester; amide-containing monomers such as (meth)acrylamide and ethyl (meth)acrylamide; nitrile group-containing monomers such as (meth)acrylonitrile; and glycidyl Examples of the monomer include epoxy group-containing monomers such as (meth)acrylates; alkoxysilyl group-containing monomers such as vinyltrimethoxysilane, vinyltriethoxysilane, γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, γ-(meth)acryloyloxypropylmethyldimethoxysilane, or silicone compounds having a polymerizable double bond; aromatic hydrocarbon monomers such as styrene, methylstyrene, chlorostyrene, vinyltoluene, and the like; and vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, and vinyl pivalate, and one or more of these can be used as necessary.

[0028] Furthermore, the (As) component contains a silicone component as a constituent. The silicone component may be in the form of a chain, branched, cyclic, or the like. The content of the silicone component is preferably 0.1 to 20 mass% (more preferably 0.5 to 10 mass%) in terms of SiO2 in the resin solids. Within the above range, it is possible to obtain an effect of improving long-term weather resistance and ensure conformability to the base (coated surface). In the present invention, "α to β" is synonymous with "α or more and β or less."

[0029] In the present invention, the SiO2 equivalent is expressed as the mass of silica (SiO2) that remains when a compound having an Si-O bond is completely hydrolyzed and then baked at 900°C. In general, alkoxysilanes, silicates, silicones, etc. react with water to undergo a hydrolysis reaction to become silanols, which then have the property of undergoing a condensation reaction between silanols or between silanols and alkoxy. When this reaction is carried to the extreme, it becomes silica (SiO2). These reactions are as follows: RO(Si(OR)2O)nR+(n+1)H2O→nSiO2+(2n+2)ROH (R represents an alkyl group. n is an integer.) The reaction is represented by the following reaction formula: In the present invention, the SiO2 equivalent is the amount of the remaining silica component calculated based on this reaction formula.

[0030] The method for introducing silicone into component (As) is not particularly limited and various methods can be used. For example, (1) A method for copolymerizing a silicone compound having a polymerizable double bond, (2) A method of reacting a functional group in a resin with a silicone compound having a functional group capable of reacting with the functional group; (3) A method of reacting a resin copolymerized with a reactive silyl group-containing monomer with a reactive silyl group-containing compound; (4) A method in which a functional group in a resin is reacted with a coupling agent having a functional group capable of reacting with the functional group, and then a reactive silyl group-containing compound is reacted therewith.

[0031] Examples of the combinations of functional groups in (2) and (4) above include a hydroxyl group and an isocyanate group, a hydroxyl group and a carboxylic anhydride group, an amino group and an isocyanate group, a carboxyl group and an epoxy group, an amino group and an epoxy group, and an alkoxysilyl group and an alkoxysilyl group.

[0032] The reactive silyl group in (3) and (4) above is a group in which an alkoxyl group, a phenoxy group, a mercapto group, an amino group, a halogen, or the like is bonded to a silicon atom. The reactive silyl group-containing compound is one having two or more reactive silyl groups in one molecule, and examples thereof include tetrafunctional alkoxysilanes such as tetraethoxysilane, tetramethoxysilane, and tetrabutoxysilane; trifunctional alkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, butyltrimethoxysilane, butyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and phenyltributoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, dipropyldimethoxysilane, and dipropyl Examples of the alkoxysilanes include diethoxysilane, dibutyldimethoxysilane, dibutyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldibutoxysilane, methylphenyldimethoxysilane, and methylphenyldiethoxysilane; chlorosilanes such as tetrachlorosilane, methyltrichlorosilane, ethyltrichlorosilane, propyltrichlorosilane, phenyltrichlorosilane, vinyltrichlorosilane, dimethyldichlorosilane, diethyldichlorosilane, diphenyldichlorosilane, and methylphenyldichlorosilane; acetoxysilanes such as tetraacetoxysilane, methyltriacetoxysilane, phenyltriacetoxysilane, dimethyldiacetoxysilane, and diphenyldiacetoxysilane, and the like. One or more of these can be used. Also, a compound having one reactive silyl group in one molecule can be used in combination.

[0033] The reactive silyl group-containing monomer in (3) above is a compound containing a reactive silyl group and a polymerizable double bond, and examples thereof include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltri-n-butoxysilane, vinyltris(β-methoxyethoxy)silane, allyltrimethoxysilane, trimethoxysilylethyl vinyl ether, triethoxysilylethyl vinyl ether, trimethoxysilylpropyl vinyl ether, triethoxysilylpropyl vinyl ether, γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, γ-(meth)acryloyloxypropylmethyldimethoxysilane, vinylmethyldimethoxysilane, methyldimethoxysilylethyl vinyl ether, methyldimethoxysilylpropyl vinyl ether, and the like. One or more of these may be used.

[0034] The coupling agent in (4) above is, for example, a compound having at least one or more alkoxysilyl groups and other substituents in one molecule.Specific examples of the coupling agent include β-(3,4 epoxycyclohexyl)ethyltrimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyltriethoxysilane, N-(β-aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-(β-aminoethyl)-γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, isocyanate functional silane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-methacryloxypropyltriethoxysilane, etc., and one or more of these can be used.

[0035] The hydroxyl value (solid content) of component (A) is preferably 5 to 200 KOHmg / g (more preferably 10 to 180 KOHmg / g, and even more preferably 30 to 150 KOHmg / g). When the above range is satisfied, excellent effects can be achieved in various coating film properties, stain resistance, etc. The hydroxyl value is a value expressed by the number of milligrams of potassium hydroxide equivalent to the moles of hydroxyl groups contained in 1 g of sample.

[0036] In the present invention, the hydroxyl value of the (As) component in the (A) component is larger than that of the (At) component. Specifically, the hydroxyl value of the (As) component is preferably 10 to 200 KOHmg / g (more preferably 20 to 180 KOHmg / g, even more preferably 30 to 150 KOHmg / g, and particularly preferably 35 to 100 KOHmg / g), and the hydroxyl value of the (At) component is preferably 5 to 200 KOHmg / g (more preferably 10 to 180 KOHmg / g, even more preferably 20 to 150 KOHmg / g, and particularly preferably 30 to 100 KOHmg / g). Furthermore, the difference in the hydroxyl value between the (As) component and the (At) component is preferably 1 to 50 KOHmg / g (more preferably 2 to 40 KOHmg / g). In such a case, the crosslink density of the coating film is increased, and excellent effects can be exhibited in weather resistance, stain resistance, adhesion, and the like.

[0037] The mixing mass ratio of the (As) component to the (At) component is preferably 99 / 1 to 50 / 50 (more preferably 98 / 2 to 60 / 40), in which case the crosslinking density is further increased, and a coating film having excellent long-term weather resistance can be formed.

[0038] The glass transition temperature of component (A) is preferably -10 to 80°C (more preferably 0 to 60°C). If the glass transition point is within this range, the coating film properties such as stain resistance, flexibility, and durability can be improved. The glass transition temperature is a value calculated by Fox's formula based on the vinyl monomer constituting the resin.

[0039] The embodiment of the component (A) of the present invention includes a non-aqueous dispersion type resin (a1) and a soluble type resin (a2), and these can be used in combination of one or more. In the present invention, the component (As) is preferably a non-aqueous dispersion type resin (a1). Furthermore, the component (At) is preferably a soluble type resin (a2). This is advantageous in terms of stain resistance, flexibility, and the like. The non-aqueous dispersion type resin (a1) is a resin dispersed as resin particles in a non-aqueous solvent. The soluble type resin (a2) is a resin dissolved in a non-aqueous solvent.

[0040] The non-aqueous solvent preferably contains an aliphatic hydrocarbon-containing non-aqueous solvent (so-called weak solvent). The aliphatic hydrocarbon-containing non-aqueous solvent is a non-aqueous solvent that is less toxic than toluene, xylene, etc., has high operational safety, and has little impact on air pollution. Examples of aliphatic hydrocarbons include n-hexane, n-pentane, n-octane, n-nonane, n-decane, n-undecane, and n-dodecane. These can be used alone or in combination of two or more. In the present invention, aliphatic hydrocarbons can also be introduced by using a mixed solvent such as mineral spirits. The aliphatic hydrocarbon is preferably contained in an amount of 5% by mass or more, more preferably 10 to 80% by mass, based on the total amount of the non-aqueous solvent.

[0041] The non-aqueous solvent may contain a solvent that can be mixed with aliphatic hydrocarbons. Examples of such solvents include petroleum-based solvents such as petroleum ether, petroleum naphtha, and solvent naphtha, as well as ethyl acetate, butyl acetate, methyl ethyl ketone, and methyl isobutyl ketone. Examples of suitable solvents include petroleum-based solvents (aromatic hydrocarbon-containing petroleum mixed solvents) having a mixed aniline point or aniline point of 12 to 70°C. The mixed aniline point or aniline point is a value measured by the method of JIS K2256:2013.

[0042] (hardening agent) The curing agent contains a polyisocyanate compound (B) and a silicate compound (C).

[0043] The (B) polyisocyanate compound (hereinafter also referred to as "component (B)") has two or more isocyanate groups in one molecule and reacts with the above-mentioned component (A) to form a coating film. The (B) component is preferably one that can crosslink with the (A) component at room temperature. The room temperature here preferably means -10°C or higher and 50°C or lower, more preferably -5°C or higher and 40°C or lower. The isocyanate group content in the solid content of the (B) component is preferably 2% by mass or higher and 30% by mass or lower.

[0044] Examples of the (B) component include derivatives of at least one diisocyanate selected from aliphatic diisocyanates and alicyclic diisocyanates, an alcohol component, and, if necessary, a polyol component, etc., which have been subjected to alphanation, biuretization, dimerization (uretidione formation), trimerization (isocyanurate formation), adductation, carbodiimide formation reaction, etc., and mixtures thereof. These can be used alone or in combination of two or more.

[0045] Aliphatic diisocyanates are compounds having saturated aliphatic groups in the molecule, such as 1,4-diisocyanatobutane, 1,5-diisocyanatopentane, 1,6-diisocyanatohexane (also known as hexamethylene diisocyanate (HDI)), 1,6-diisocyanato-2,2,4-trimethylhexane, methyl 2,6-diisocyanatohexanoate (lysine diisocyanate), etc. On the other hand, alicyclic diisocyanates are compounds having cyclic aliphatic groups in the molecule, such as 5-isocyanato-1-isocyanatomethyl-1,3,3-trimethylcyclohexane (isophorone diisocyanate), 1,3-bis(isocyanatomethyl)cyclohexane (hydrogenated xylylene diisocyanate), bis(4-isocyanatocyclohexyl)methane (hydrogenated diphenylmethane diisocyanate), 1,4-diisocyanatocyclohexane, etc. Among these, HDI is the most preferable because it has excellent weather resistance and flexibility. (Hereinafter, aliphatic diisocyanates and alicyclic diisocyanates will be collectively referred to as "diisocyanates.")

[0046] Examples of the alcohol component include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, isobutanol, 1-pentanol, 2-pentanol, isoamyl alcohol, 1-hexanol, 2-hexanol, 1-heptanol, 1-octanol, 2-ethyl-1-hexanol, 3,3,5-trimethyl-1-hexanol, tridecanol, pentadecanol, palmityl alcohol, stearyl alcohol, cyclopentanol, cyclohexanol, methylcyclohexanol, trimethylcyclohexanol, etc. These can be used alone or in combination of two or more.

[0047] Examples of the polyol component include polyether polyol, polyester polyol, polyolefin polyol, etc. In the present invention, polyether polyols such as polypropylene triol, polypropylene glycol, polytetramethylene glycol, etc. are particularly suitable. These can be used alone or in combination of two or more.

[0048] In the present invention, it is preferable to include a polyisocyanate compound (b1) (hereinafter referred to as "(b1) component") having an isocyanate group content of less than 14% by mass (preferably 2% by mass or more and 13% by mass or less) in the solid content, and a polyisocyanate compound (b2) (hereinafter referred to as "(b2) component") having an isocyanate group content of 14% by mass or more (preferably 15% by mass or more and 30% by mass or less). By using the above (b1) component and (b2) component in combination, it is possible to achieve excellent effects in terms of contamination resistance and conformability to the base. As a result, even if the surface to be coated has a joint material such as a sealant, excellent conformability can be obtained. In addition, excellent effects can be obtained in terms of crack resistance (flexibility). In particular, in the present invention, it is possible to achieve excellent effects in adhesion and conformability to a surface to be coated having both an undercoat material and a joint material. In the present invention, the isocyanate group content is defined as the content (mass%) of isocyanate groups contained in the solid content of a polyisocyanate compound, and is a value determined by back titration with hydrochloric acid after neutralizing the isocyanate groups with an excess of amine.

[0049] In the present invention, the component (B) preferably contains 20 to 90% by mass (more preferably 30 to 80% by mass, and even more preferably 45 to 75% by mass) of the above-mentioned (B1). In such a range, the above-mentioned effects can be further enhanced.

[0050] The mixing ratio of the (B) component may be set in consideration of the molar ratio [NCO] / [OH] between the isocyanate groups of the (B) component and the hydroxyl groups of the (A) component. The molar ratio [NCO] / [OH] between the isocyanate groups of the (B) component and the hydroxyl groups of the (A) component is preferably 0.6 to 1.4 (more preferably 0.8 to 1.3). With such a ratio, the effects of the present invention can be further enhanced.

[0051] The mixing ratio (mass ratio) of the (A) component and the (B) component is set by the hydroxyl value of the (A) component and the isocyanate group content of the (B) component, but in the topcoat material of the present invention, the mixing ratio of the (B) component is preferably 5 to 50 parts by mass (more preferably 10 to 40 parts by mass) per 100 parts by mass of the resin solids of the (A) component.

[0052] The silicate compound (C) (hereinafter also referred to as "component (C)") mainly has the function of imparting hydrophilicity to the formed coating film. Examples of such component (C) that can be used include tetraalkoxysilane, tetraalkoxysilane condensates, and modified products thereof. Examples of tetraalkoxysilane include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetra-n-butoxysilane, tetraisobutoxysilane, tetra-sec-butoxysilane, tetra-t-butoxysilane, tetraphenoxysilane, monoethoxytrimethoxysilane, monobutoxytrimethoxysilane, monopentoxytrimethoxysilane, monohetoxytrimethoxysilane, dimethoxydiethoxysilane, and dimethoxydibutoxysilane. These can be used alone or in combination of two or more.

[0053] In the present invention, it is preferable to use a tetraalkoxysilane condensate (c1) (hereinafter referred to as "component (c1)") containing an alkoxyl group having 1 to 2 carbon atoms and an alkoxyl group having 3 to 12 carbon atoms. In particular, the component (c1) is preferably modified at a modification rate such that 5% by mass to 50% by mass of the alkoxyl groups in the entire compound are alkoxyl groups having 3 to 12 carbon atoms.

[0054] Examples of alkoxyl groups having 3 to 12 carbon atoms include linear alkoxyl groups such as n-propoxy, n-butoxy, n-pentyloxy, n-hexyloxy, n-octyloxy, and n-dodecyloxy groups, and branched alkoxyl groups such as isopropoxy, isobutoxy, t-butoxy, sec-butoxy, isopentyloxy, neopentyloxy, isohexyloxy, 3-methylpentyloxy, 1-methylhexyloxy, 1-ethylpentyloxy, 2,3-dimethylbutoxy, 1,5-dimethylhexyloxy, 2-ethylhexyloxy, 1-methylheptyloxy, and t-octyloxy groups.

[0055] Such a component (c1) can be produced by a known method, such as a method of modifying a tetraalkoxysilane condensate having an alkoxyl group having 1 to 2 carbon atoms with an alcohol having 3 to 12 carbon atoms.

[0056] The mixing ratio of the (C) component is preferably 0.1 to 50 parts by mass (more preferably 1 to 30 parts by mass) per 100 parts by mass of the resin solid content of the (A) component. If the (C) component is in this range, excellent stain resistance effects can be obtained.

[0057] The mixing ratio of the (B) component to the (C) component is preferably 5 to 80 parts by mass (more preferably 10 to 60 parts by mass) of the (C) component per 100 parts by mass of the solid content of the (B) component. If the (C) component is in this range, excellent stain resistance effects and the like can be obtained.

[0058] The curing agent of the present invention can be produced by uniformly stirring and mixing the above components (B) and (C) by a conventional method.

[0059] In addition to the above-mentioned components, the topcoat material of the present invention preferably contains a powder component (D) (hereinafter also referred to as "component (D)") in the base agent and / or hardener. Examples of component (D) include color pigments and extender pigments.

[0060] As the color pigment, a chromatic pigment, a white pigment, a black pigment, etc. can be used. By including such a color pigment, it is possible to express various colors. Among them, the chromatic pigment is a pigment that exhibits a chromatic color such as yellow, orange, red, green, blue, purple, etc. Examples of such chromatic pigments include inorganic pigments such as ferric oxide, ferric oxide hydrous, ultramarine, cobalt blue, and cobalt green, and organic pigments such as azo, naphthol, pyrazolone, anthraquinone, perylene, quinacridone, disazo, isoindolinone, benzimidazole, phthalocyanine, and quinophthalone. On the other hand, the white pigment is a pigment that exhibits white color, and examples thereof include titanium oxide, zinc oxide, and aluminum oxide. The black pigment is a pigment that exhibits a black color, and examples thereof include inorganic pigments such as iron black, iron-manganese composite oxide, iron-copper-manganese composite oxide, iron-chromium-cobalt composite oxide, copper-chromium composite oxide, copper-manganese-chromium composite oxide, and carbon black. These can be used alone or in combination of two or more. The surface of the pigment may be treated in some way.

[0061] The average particle size of the color pigment is preferably 1 μm or less, more preferably 0.01 to 0.9 μm. The average particle size of the color pigment is a value measured by a laser diffraction particle size distribution measuring device. The mixing ratio of the color pigment is preferably 1 to 200 parts by mass (more preferably 5 to 150 parts by mass) per 100 parts by mass of the solid content of the component (A).

[0062] The extender pigment can be used for the purpose of, for example, adjusting the solid content, adjusting the viscosity, adjusting the gloss (reducing the gloss, etc.), or improving the storage stability and pigment miscibility. Examples of the extender pigment include heavy calcium carbonate, light calcium carbonate, kaolin, clay, bentonite, china clay, diatomaceous earth, hydrous fine powder of silicic acid, talc, baryte powder, barium sulfate, precipitated barium sulfate, barium carbonate, magnesium carbonate, silica powder, aluminum hydroxide, etc., which may be subjected to some treatment (surface treatment, etc.). These can be used alone or in combination of two or more kinds.

[0063] The average particle size of the extender pigment is preferably 0.01 to 10 μm (preferably 0.05 to 5 μm). The average particle size of the extender pigment is a value measured by a laser diffraction particle size distribution measuring device. The blending ratio of the extender pigment is preferably 1 to 150 parts by mass (more preferably 5 to 100 parts by mass) per 100 parts by mass of the solid content of component (A).

[0064] The mixing ratio of the (D) component is preferably 1 to 300 parts by mass (more preferably 5 to 250 parts by mass) relative to 100 parts by mass of the solid content of the (A) component. When the (D) component contains a powder component (d1) (hereinafter also referred to as the "(d1) component") having a true specific gravity (density) of 3.0 or more, it is preferable to contain a powder component (d2) (hereinafter also referred to as the "(d2) component") having a true specific gravity (density) of less than 3.0 in combination. The mixing mass ratio [(d1) / (d2)] of the (d2) component to the (d1) component is preferably 99.5 / 0.5 to 70 / 30 (more preferably 99 / 1 to 80 / 20). This enhances the dispersion stability of the (D) component relative to the (A) component, and allows excellent pigment compatibility, color stability, and gloss to be obtained. It is also advantageous in improving weather resistance. The reason why such an effect is exhibited is not limited, but it is presumed that by using the (d2) component in combination with the (d1) component having a large specific gravity, the (d2) component acts as a spacer for the (d1) component, thereby enhancing the dispersion stability of the (d1) component.

[0065] In addition, the topcoat material of the present invention may contain various components in the main agent and / or hardener, in addition to the above-mentioned components, to the extent that the effect of the present invention is not affected. Such components include, for example, catalysts, plasticizers, preservatives, antifungal agents, antialgae agents, defoamers, leveling agents, pigment dispersants, thickeners, antiskinning agents, dehydrating agents, matting agents, UV absorbers, light stabilizers, antioxidants, solvents, etc. In addition, it may contain resin components other than the above-mentioned (A) component. The topcoat material of the present invention is a two-liquid coating material consisting of a main agent and a hardener, and is used by mixing the main agent and hardener when painting.

[0066] The topcoat material of the present invention can be diluted at the time of application. As the diluent, the above-mentioned aliphatic hydrocarbon-containing non-aqueous solvent is preferable.

[0067] As a method for applying the topcoat material, various methods can be adopted, such as brush coating, roller coating, spray coating, etc. The amount of coating applied at the time of coating is preferably 30 to 250 g / m per coating. 2 , more preferably 50 to 200 g / m 2 In addition, after painting is performed once and the coating film is dried, the next painting (recoating) can be performed. The drying temperature is preferably -10 to 50°C, more preferably -5 to 40°C. The number of coatings is preferably two or more. EXAMPLES

[0068] The following examples will clarify the features of the present invention. (A) Polyol compound (A1) Silicone-containing acrylic polyol compound dispersion (solid content: 50% by mass, hydroxyl value (solid content): 55 KOH mg / g, silicone component content: 3% by mass (SiO2 equivalent), Tg: 30°C, medium: mineral spirits) (A2) Acrylic polyol compound dispersion (solid content: 50% by mass, hydroxyl value (solid content): 55 KOHmg / g, Tg: 30°C, medium: mineral spirits) (A3) Acrylic polyol compound dispersion (solid content: 50% by mass, hydroxyl value (solid content): 28 KOH mg / g, Tg: 30° C., medium: mineral spirits) (A4) Silicone-containing acrylic polyol compound solution (solid content: 50% by mass, hydroxyl value (solid content): 28 KOHmg / g, silicone component content: 3% by mass (SiO2 equivalent), Tg: 32°C, medium: mineral spirits) (A5) Acrylic polyol compound solution (solid content: 50% by mass, hydroxyl value (solid content): 40 KOH mg / g, Tg: 32°C, medium: mineral spirits) (A6) Acrylic polyol compound solution (solid content: 50% by mass, hydroxyl value (solid content): 28 KOH mg / g, Tg: 32°C, medium: mineral spirits) The above (A1) to (A3) are non-aqueous dispersion type resins (a1), and the above (A4) to (A6) are soluble type resins (a2). (B) Polyisocyanate compound (B1) Hexamethylene diisocyanate derivative solution (solid content: 100% by mass, isocyanate group content: 12% by mass) (B2) Hexamethylene diisocyanate derivative solution (solid content: 100% by mass, isocyanate group content: 21% by mass) (B3) Hexamethylene diisocyanate derivative solution (solid content: 100% by mass, isocyanate group content: 17% by mass) (C) Silicate compounds (C1) Tetramethoxysilane (C2) i-Butyl alcohol modified tetramethoxysilane compound (average condensation degree 4, modification rate 30%, residual silica rate 40%) (D) Pigments (D1) Rutile titanium dioxide (specific gravity 4, average particle size 0.45 μm) (D2) Kaolin clay (specific gravity 2.6, average particle size 0.8 μm) (D3) Organically modified bentonite (specific gravity 1.5, average particle size 0.5 μm) (solvent) Aliphatic hydrocarbon-containing non-aqueous solvent: mineral spirits (Additives) Defoamers, thickeners, etc.

[0069] <Preparation of topcoat material 1> Manufacturing of base agent 1 Base agent 1 was prepared by mixing and stirring 48 parts by mass of component (A1), 12 parts by mass of component (A5), 25 parts by mass of component (D1), 10 parts by mass of solvent, and 5 parts by mass of additive. - Preparation of hardener 1 Curing agent 1 was prepared by mixing and stirring 5.8 parts by mass of the component (B2), 3 parts by mass of the component (C1), and 11.2 parts by mass of the solvent. Preparation of topcoat material 1 The base agent 1 (100 parts by mass) and the hardener 1 (20 parts by mass) were mixed ([NCO] / [OH]=1.04) and stirred immediately before painting to obtain topcoat material 1.

[0070] <Preparation of topcoat materials 2 to 13> Except for the change to the formulation in Table 1, the components were mixed and stirred in the same manner as in topcoat material 1 to prepare the base agent and hardener, and then mixed just before painting to obtain topcoat materials 2 to 13.

[0071] [Table 1]

[0072] (Examples 1 to 10, Comparative Examples 1 to 3) The following evaluations [A] (evaluations [A-1] and [A-2]) were performed on the above-mentioned topcoat materials 1 to 13. The results are shown in Table 2.

[0073] <Preparation of test specimen> Two ceramic siding boards measuring 100mm x 300mm x 6mm were placed side by side, and the joint between the boards (width 10mm) was filled with a modified silicone sealant (resin component: alkoxysilyl group-containing polyether polymer, plasticizer content: less than 1% by mass) to create the surface to be painted. Next, the undercoat material was applied. The method for applying the undercoat material was as follows. (I) Apply 0.3 kg / m of primer (epoxy primer) to the entire surface of the above-mentioned coating. 2 The paint was applied by roller (using a wool roller) and allowed to dry for 8 hours. (II) After the sealing joints of the above-mentioned coated surface are covered with a masking material, a primer (epoxy-based primer) is applied in an amount of 0.3 kg / m. 2 The paint was applied by roller (using a wool roller) and allowed to dry for 8 hours, after which the masking material was removed. (III) Apply 0.3 kg / m of primer (epoxy primer) to the entire surface of the above-mentioned coating. 2After applying the primer, within 10 to 25 minutes, smooth the primer applied to the joints with a cloth so that the amount of paint applied to the joints is approximately 0.05 kg / m2. 2 The mixture was then dried for 8 hours. The coating amount of the topcoat material applied to the surface obtained in (I) to (III) above is 150 g / m 2 Spray paint twice (total amount of paint 300g / m 2 ) and dried for 7 days to prepare the test specimens. All painting and drying was carried out under standard conditions (temperature 23°C, relative humidity 50%).

[0074] Rating: A-1 Carbon dispersion (1%) was sprayed onto each test specimen, dried (60°C, 1 hour), and then washed with water. The difference in brightness (ΔL value) between the test specimens before and after contamination was measured, and the stain resistance test was evaluated. The ΔL value was measured using a TC-1800 color difference meter (manufactured by Tokyo Denshoku Co., Ltd.). The evaluation criteria are: AA: Lightness difference (ΔL value) is less than 5 A: Lightness difference (ΔL value) is 5 or more and less than 10 B: Lightness difference (ΔL value) is 10 or more and less than 20 C: Lightness difference (ΔL value) is 20 or more and less than 30 D: Lightness difference (ΔL value) is 30 or more

[0075] Rating: [A-2] Each specimen was subjected to a total of 10 cycles of repeated hot and cold tests, each cycle consisting of 18 hours of water immersion, 3 hours at -20°C, and 3 hours at 50°C, after which the appearance of the coating at each site (connecting parts, plate parts) was checked and the occurrence of defects (blistering, peeling, cracks, etc.) was evaluated. The evaluation was done on a 5-point scale (Excellent: AA>A>B>C>D: Poor), with "AA" indicating no defects and "D" indicating obvious defects. [Table 2]

Claims

1. A coating method for applying a topcoat material to a coating surface having a joint, The above-mentioned topcoat material has a base agent and a hardener, The base material contains a hydroxyl group-containing resin (A), The curing agent contains a polyisocyanate compound (B) and a silicate compound (C), The hydroxyl-containing resin (A) includes a hydroxyl-containing resin (As) containing a silicone component and another hydroxyl-containing resin (At), A coating method characterized in that the hydroxyl value of the silicone-containing hydroxyl-containing resin (As) is greater than the hydroxyl value of the other hydroxyl-containing resins (At).

2. 2. The coating method according to claim 1, wherein the hydroxyl-containing resin (As) containing a silicone component is a non-aqueous dispersion type resin (a1).

3. The coating method according to claim 1 or 2, characterized in that the polyisocyanate compound (B) contains a polyisocyanate compound (b1) having an isocyanate group content of less than 14 mass% and a polyisocyanate compound (b2) having an isocyanate group content of 14 mass% or more.

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