Coating composition and method for repairing building exterior materials

Abstract

To provide a paint composition capable of forming a coated film excellent in adhesion to a surface where a photocatalyst is present, an inorganic substrate and an inorganic coated film, and also excellent in weather resistance and frost damage resistance.SOLUTION: A two-component or multi-component paint composition containing at least (A) a main agent and (B) a curing agent, wherein (A) the main agent comprises (A-1) a resin having a silanol group, and (B) the curing agent contains (B-1) : an organosilicate represented by a general formula: Si(OR)4 (wherein, R is the same or different, and is an organic group having 1-8 carbon atoms.) and / or a partial condensate of the organosilicate, for a coating film formed from the coating composition, a silicon content contained in the resin constituting the coating film is 5.0-15.0 mass%, and for the coating film formed from the coating composition, a degree of elongation at 23°C is 15% or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a coating composition and a method for repairing architectural exterior materials using said coating composition, and in particular to a coating composition that exhibits excellent adhesion to surfaces in the presence of a photocatalyst, inorganic substrates, and inorganic coating films, and is capable of forming coating films that are also excellent in weather resistance and frost resistance. [Background technology]

[0002] In recent years, exterior wall materials such as siding boards used for the exterior of buildings have become more sophisticated in design and functionality, and a wide range of paints, such as fluorine-based paints, inorganic paints, ceramic modified paints, and paints containing photocatalysts, have been studied and put into practical use to protect the surfaces of these materials, with the aim of improving weather resistance and stain resistance. When the coating on the surface of these exterior wall materials deteriorates over time, scratches and peeling occur, making repairs necessary. One method of repair is to repair with clear paint in order to make the most of the existing coating with high design quality. One method of repairing with clear paint is to paint a transparent sealer (clear sealer) and then a transparent, highly weather-resistant paint (top clear), and paints suitable for repairs are being studied.

[0003] JP 2013-208546 A (Patent Document 1) describes a method for repairing an architectural exterior material, which comprises the steps of removing contaminants on an old coating film on the surface of the architectural exterior material without peeling or removing the old coating film, applying an aqueous undercoat paint containing an aqueous dispersion (A) and an adhesion promoter (C) onto the old coating film to form an undercoat coating film, and applying an aqueous topcoat paint containing an aqueous dispersion (B) onto the undercoat coating film to form a topcoat coating film. Here, it is described that the aqueous dispersion (A) and the aqueous dispersion (B) preferably contain an acrylic silicone resin emulsion, and the adhesion promoter (C) preferably contains an epoxy group-containing silane coupling agent.

[0004] Japanese Patent Application Laid-Open No. 2012-251094 (Patent Document 2) describes a water-based undercoat paint composition for repair, which contains an anionic or cationic resin emulsion (A), a glycidyl group-containing silane coupling agent (B), and an amino group-containing silane coupling agent (C) in specific ratios.

[0005] JP 2020-168595 A (Patent Document 3) describes a coating formation method in which a first coating material and a second coating material are applied to an existing coating surface provided on a substrate to form a new coating, wherein the first coating material and the second coating material each contain a resin component that contains 20% by weight or more of a (meth)acrylic acid alkyl ester (A) having an alkyl group with 3 or more carbon atoms in the resin constituents, and form a coating that is visible light transmissive and has an ultraviolet ray transmittance of 30% or less, and the resin component of the first coating material further contains an epoxy group-containing monomer in the resin constituents.

[0006] The water-based undercoat paint described in Patent Document 1, the water-based undercoat paint composition described in Patent Document 2, and the first coating material described in Patent Document 3 can be said to have excellent adhesion to organic coating films, but there are problems with adhesion to inorganic coating films. In this regard, coating compositions that also have excellent adhesion to inorganic coating films are also known.

[0007] Japanese Patent Laid-Open Publication No. 2012-250233 (Patent Document 4) describes a coating method for applying to an inorganic substrate a curable composition containing (I) an alkoxysilyl group-containing synthetic resin emulsion, (II) a substance that accelerates the hydrolysis and condensation of the alkoxysilyl groups, and (III) an organosilicate and / or a modified product thereof.

[0008] Japanese Patent Laid-Open Publication No. 2019-19260 (Patent Document 5) describes a primer composition that further contains, in addition to the components (I) to (III) described in Patent Document 4, (IV) an isocyanate compound and (V) a ketoimino group-containing alkoxysilane compound. It is claimed that this makes it possible to provide an aqueous primer that ensures adhesion to inorganic coating films while improving adhesion to organic coating films such as fluorine-based and urethane-based coating films.

[0009] The inventions described in Patent Document 4 and Patent Document 5 aim to solve the problems related to adhesion to inorganic coating films and inorganic substrates. However, the curable composition described in Patent Document 4 and the primer composition described in Patent Document 5 were not sufficient for application to surfaces on which a photocatalyst exists. Exterior wall materials on which a photocatalyst exists on the surface often have an undercoat coating film arranged on the substrate, a photocatalyst layer containing a photocatalyst as a surface layer, and a barrier layer between the undercoat coating film and the photocatalyst layer to protect the undercoat coating film from photocatalytic action. In addition to containing a large amount of inorganic components, the photocatalyst layer and the barrier layer may have photocatalyst remaining on the surface layer. For this reason, when repairing an exterior wall material using a composition such as the curable composition described in Patent Document 4 or the primer composition described in Patent Document 5, there was a problem with adhesion. In particular, when the paint used for repair is a clear paint, when the paint film applied to a surface containing a photocatalyst is exposed to the outdoor environment, the photocatalyst underneath the paint film becomes activated, and the photocatalytic action and the cycle of freezing at night and rising temperatures during the day are repeated, causing the repair paint film to crack and peel off. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] JP 2013-208546 A [Patent Document 2] JP 2012-251094 A [Patent Document 3] JP 2020-168595 A [Patent Document 4] JP 2012-250233 A [Patent Document 5] JP 2019-19260 A Summary of the Invention [Problem to be solved by the invention]

[0011] Therefore, an object of the present invention is to provide a coating composition capable of forming a coating film having excellent adhesion to a surface on which a photocatalyst is present, an inorganic substrate, and an inorganic coating film, as well as excellent weather resistance and frost resistance. Another object of the present invention is to provide a method for repairing a building exterior material using the coating composition. [Means for solving the problem]

[0012] As a result of intensive research into achieving the above object, the present inventors have discovered that a silanol-containing resin is used as the base material, and the curing agent is a compound represented by the general formula: Si(OR) 4 The inventors have found that, with respect to a coating film formed from a two-liquid or multi-component coating composition containing an organosilicate represented by the formula: (wherein R are the same or different and are organic groups having 1 to 8 carbon atoms) and / or a partial condensate of said organosilicate, when the silicon content in the resin constituting said coating film is 5.0 to 15.0 mass % and the elongation of said coating film at 23°C is 15% or more, it is possible to form a coating film which is excellent in adhesion to surfaces where a photocatalyst is present, inorganic substrates, and inorganic coating films, and which is also excellent in weather resistance and frost resistance, and have thus completed the present invention.

[0013] Therefore, the coating composition of the present invention is a two-component or multi-component coating composition containing at least (A) a base agent and (B) a curing agent, (A) the base agent contains (A-1) a resin having a silanol group, (B) The curing agent is (B-1) General formula: Si(OR) 4[wherein R are the same or different and each R is an organic group having 1 to 8 carbon atoms] and / or a partial condensate of the organosilicate, Regarding the coating film formed from the coating composition, the silicon content in the resin constituting the coating film is 5.0 to 15.0 mass %, The coating composition is characterized in that a coating film formed from the coating composition has an elongation percentage of 15% or more at 23°C.

[0014] In a preferred embodiment of the coating composition of the present invention, the (A-1) resin having a silanol group has a urethane structure.

[0015] In addition, the method for repairing an architectural exterior material of the present invention is a method for repairing an architectural exterior material, which comprises the steps of removing contaminants on an old coating film on the surface of the architectural exterior material without peeling or removing the old coating film, applying the above-mentioned paint composition of the present invention onto the old coating film to form an undercoat coating film, and applying a topcoat paint onto the undercoat coating film to form a topcoat coating film. Effect of the Invention

[0016] According to the coating composition of the present invention, it is possible to provide a coating composition capable of forming a coating film having excellent adhesion to a surface on which a photocatalyst is present, an inorganic substrate, and an inorganic coating film, as well as excellent weather resistance and frost resistance. Also, according to the method for repairing an architectural exterior material of the present invention, it is possible to provide a method for repairing an architectural exterior material using such a coating composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention relates to a coating composition and a method for repairing building exterior materials using the coating composition.

[0018] The coating composition of the present invention is a two-liquid or multi-component coating composition containing at least a base agent and a curing agent, the base agent containing a resin having a silanol group, and the curing agent containing a silanol group and a curing agent having the general formula: Si(OR) 4(wherein R are the same or different and each R is an organic group having 1 to 8 carbon atoms.) and / or a partial condensate of the organosilicate.

[0019] In this specification, the "main agent" contained in the coating composition of the present invention may be referred to as "main agent (A)" and the "curing agent" may be referred to as "curing agent (B)". In addition, the "resin having a silanol group" contained in the main agent (A) may be referred to as "component (A-1)" or "resin having a silanol group (A-1)", and the "component having the general formula: Si(OR) 4 [wherein R are the same or different and each R is an organic group having 1 to 8 carbon atoms] and / or a partial condensate of said organosilicate" is referred to as "component (B-1)" or "(B-1) general formula: Si(OR) 4 [wherein R are the same or different and each R is an organic group having 1 to 8 carbon atoms] and / or a partial condensate of said organosilicate.

[0020] In the present invention, a "two-component coating composition" means a coating composition consisting of a base agent and a curing agent, and a "multi-component coating composition" means a coating composition consisting of a base agent, a curing agent, and one or more additives.

[0021] The (A) base agent contains a resin having a silanol group. Here, the silanol group means a hydroxyl group (SiOH group) bonded to a silicon atom. The (A-1) component reacts with the (B-1) component via the silanol group during coating, thereby improving adhesion to surfaces on which a photocatalyst is present, inorganic substrates, and inorganic coating films.

[0022] In this specification, the inorganic coating film refers to a coating film containing a resin having a polysiloxane structure, such as a silicone resin or its modified resin (such as an acrylic silicone resin). In addition, the inorganic substrate refers to an inorganic substrate such as cement or mortar, or a composite substrate made by combining the materials of these substrates with other materials.

[0023] The resin (A-1) having a silanol group preferably has a urethane structure. In the present invention, as described later, the frost resistance of the coating film is improved by adjusting the elongation of the coating film obtained and the silicon content contained in the resin constituting the coating film, but the frost resistance of the coating film obtained can be further improved by using the component (A-1) having a urethane structure (NHCOO). In addition, the component (A-1) having a urethane structure (NHCOO) is highly effective in increasing the elongation of the coating film.

[0024] The (A-1) component having a urethane structure (NHCOO) is preferably a composite resin formed by bonding a hydrophilic group-containing polyurethane and a vinyl polymer via a polysiloxane. Here, the hydrophilic group-containing polyurethane is preferably one obtained by reacting one or more hydrophilic group-containing polyols selected from the group consisting of polyether polyols, polycarbonate polyols, and polyester polyols with a polyisocyanate. The hydrophilic group-containing polyurethane is not particularly limited and various types can be used, but those having a number average molecular weight of 3000 to 100000 and those having no or a small amount of aromatic rings are preferred in order to form a coating film with excellent weather resistance.

[0025] The (A-1) resin having a silanol group preferably has a silicon content of 5 to 15 mass %.

[0026] In this specification, the silicon content in component (A-1) refers to the proportion of silicon atoms that make up component (A-1), and can be determined as follows. (0) Prepare a resin dispersion or resin solution as a sample. (i) Weigh out 3 g of sample into a magnetic crucible of known mass at constant weight. (ii) The sample in the porcelain crucible is heated at 150° C. for 30 minutes, and then further heated at 550° C. for 2 hours to incinerate the sample. (iii) Allow the ashed sample to cool to room temperature, then weigh the sample. Calculate the ash content according to the following formula: Ash content (mass%) = mass of ashed sample (g) / (mass of sample before heating (g) x resin ratio) x 100 Here, since the ash has a silicon dioxide structure, the proportion of silicon atoms can be calculated as follows: Silicon atom ratio (mass%) = ash content (mass%) × 28.1 ÷ 60.1 Since the ash may contain inorganic components other than silicon atoms, the presence and ratio of inorganic components other than silicon atoms can be confirmed by elemental analysis such as fluorescent X-rays on the obtained ash.

[0027] The (A-1) resin having a silanol group is preferably a water-dispersible resin. In this specification, a water-dispersible resin is a resin that can be distributed in water to form a heterogeneous system (e.g., an emulsion or suspension). The water-dispersible resin preferably includes an emulsion resin. The emulsion resin is a water-dispersible resin that can have a large molecular weight and has excellent dispersion stability.

[0028] In the coating composition of the present invention, when the resin having silanol groups (A-1) is a water-dispersible resin, the average particle size of the resin having silanol groups (A-1) is preferably 20 to 150 nm, more preferably 20 to 120 nm. In addition, when the coating composition of the present invention contains a plurality of resins having different average particle sizes, the proportion of the component (A-1) having an average particle size of 20 to 100 nm, preferably 30 to 70 nm, is preferably 50 mass % or more of the total resin.

[0029] In this specification, the average particle size is the 50% particle size (D 50 ) and can be obtained from the particle size distribution measured using a particle size distribution measuring device (for example, a laser diffraction / scattering particle size distribution measuring device). Particle size is expressed as the sphere-equivalent diameter measured by the laser diffraction / scattering method.

[0030] The (A-1) resin having a silanol group is preferably a composite resin formed by bonding a hydrophilic group-containing polyurethane and a vinyl polymer via a polysiloxane. In this specification, such a composite resin may be referred to as the (a) component or the (a) composite resin, the hydrophilic group-containing polyurethane constituting the (a) composite resin may be referred to as the (a1) component or the (a1) hydrophilic group-containing polyurethane, the vinyl polymer may be referred to as the (a2) component or the (a2) vinyl polymer, and the polysiloxane may be referred to as the (a3) ​​component or the (a3) ​​polysiloxane.

[0031] (a) The composite resin has a silanol group. The silanol group is mainly derived from a silanol group-containing vinyl polymer or a hydrolyzable silyl group, but the silanol group may be present in the polysiloxane.

[0032] The composite resin (a) has a hydrophilic group. The hydrophilic group is mainly derived from the hydrophilic group-containing polyurethane (a1), but the hydrophilic group may be present in the vinyl polymer (a2).

[0033] The hydrophilic group includes an anionic group, a cationic group, and a nonionic group.

[0034] Examples of the anionic group include a carboxyl group, a carboxylate group, a sulfonic acid group, and a sulfonate group.

[0035] The anionic groups of the (a) composite resin may be partially or completely neutralized with a basic compound, etc. Examples of basic compounds that can be used to neutralize the anionic groups include organic amines such as ammonia, triethylamine, pyridine, and morpholine, alkanolamines such as monoethanolamine, and metal base compounds containing Na, K, Li, Ca, etc.

[0036] An example of the cationic group is a tertiary amino group.

[0037] The tertiary amino groups of the (a) composite resin may be partially or completely neutralized with an acid, etc. Examples of acids that can be used to neutralize the tertiary amino groups include organic acids such as acetic acid, propionic acid, lactic acid, and maleic acid, organic sulfonic acids such as sulfonic acid and methanesulfonic acid, and inorganic acids such as hydrochloric acid, sulfuric acid, orthophosphoric acid, and orthophosphorous acid.

[0038] (a) The tertiary amino groups of the composite resin may be partially or entirely quaternized. Examples of the quaternizing agent include dialkyl sulfates such as dimethyl sulfate and diethyl sulfate, alkyl halides such as methyl chloride, ethyl chloride and benzyl chloride, sulfonic acids such as methyl methanesulfonate and methyl p-toluenesulfonate, and epoxies such as ethylene oxide, propylene oxide and epichlorohydrin.

[0039] Examples of the nonionic group include polyoxyalkylene groups such as a polyoxyethylene group, a polyoxypropylene group, a polyoxybutylene group, a poly(oxyethylene-oxypropylene) group, and a polyoxyethylene-polyoxypropylene group.

[0040] The amount of the new hydrophilic group contained in the (a) composite resin is preferably 50 to 1000 mmol / kg based on the entire (a) composite resin.

[0041] The ratio of the polysiloxane-derived structure (a3) ​​to the entire composite resin (a) is preferably 15 to 55 mass%, more preferably 20 to 55 mass%. In addition, the mass ratio of the hydrophilic group-containing polyurethane (a1) to the vinyl polymer (a2) in the composite resin (a) [(a2) / (a1)] is preferably 20 / 1 to 1 / 20, more preferably 15 / 1 to 1 / 20, even more preferably 10 / 1 to 1 / 20, and particularly preferably 5 / 1 to 1 / 20.

[0042] The bond between the (a1) hydrophilic group-containing polyurethane and the (a3) ​​polysiloxane is preferably a bond formed, for example, by a reaction between the hydrolyzable silyl and / or silanol groups of the (a1) hydrophilic group-containing polyurethane and the hydrolyzable silyl and / or silanol groups of the (a3) ​​polysiloxane. The bond between the (a2) vinyl polymer and the (a3) ​​polysiloxane is preferably a bond formed, for example, by a reaction between the hydrolyzable silyl and / or silanol groups of the (a2) vinyl polymer and the hydrolyzable silyl and / or silanol groups of the (a3) ​​polysiloxane.

[0043] The (a1) hydrophilic group-containing polyurethane preferably has a number average molecular weight of 3,000 to 100,000.

[0044] In this specification, the number average molecular weight is a value measured by gel permeation chromatography (GPC), using polystyrene as the standard substance and tetrahydrofuran as the mobile phase.

[0045] The amount of new hydrophilic groups contained in the (a1) hydrophilic group-containing polyurethane is preferably 50 to 1000 mmol / kg based on the entire (a1) hydrophilic group-containing polyurethane.

[0046] As the (a1) hydrophilic group-containing polyurethane, for example, a polyurethane obtained by reacting a polyol with a polyisocyanate can be used. The hydrophilic group of the (a1) hydrophilic group-containing polyurethane can be introduced by using a hydrophilic group-containing polyol as a part of the polyol.

[0047] As the polyol that can be used in the production of the (a1) hydrophilic group-containing polyurethane, for example, a hydrophilic group-containing polyol can be used in combination with another polyol.

[0048] Examples of the hydrophilic group-containing polyol include carboxyl group-containing polyols such as 2,2'-dimethylolpropionic acid, 2,2'-dimethylolbutanoic acid, 2,2'-dimethylolbutyric acid, and 2,2'-dimethylolvaleric acid, and sulfonic acid group-containing polyols such as 5-sulfoisophthalic acid, sulfoterephthalic acid, 4-sulfophthalic acid, and 5[4-sulfophenoxy]isophthalic acid. In addition, examples of the hydrophilic group-containing polyol include hydrophilic group-containing polyester polyols obtained by reacting the above-mentioned low molecular weight hydrophilic group-containing polyol with various polycarboxylic acids such as adipic acid.

[0049] Examples of polyols that can be used in combination with the hydrophilic group-containing polyol include polyether polyols, polycarbonate polyols, and polyester polyols.

[0050] As the polyether polyol, for example, one obtained by addition polymerization of an alkylene oxide using one or more compounds having two or more active hydrogen atoms as an initiator can be used.

[0051] Examples of the initiator include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, neopentyl glycol, glycerin, trimethylolethane, and trimethylolpropane.

[0052] Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin, and tetrahydrofuran.

[0053] As the polycarbonate polyol, for example, one obtained by reacting a carbonate ester with a polyol, or one obtained by reacting phosgene with bisphenol A or the like can be used.

[0054] As the carbonate ester, methyl carbonate, dimethyl carbonate, ethyl carbonate, diethyl carbonate, cyclocarbonate, diphenyl carbonate, etc. can be used.

[0055] Examples of polyols that can react with carbonate esters include ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 1,2-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,5-hexanediol, 2,5-hexanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 3-methyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, and 2-ethyl-1,3-hexanediol. Examples of the polyether polyol include dihydroxy compounds having relatively low molecular weights, such as xanediol, 2-methyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2-butyl-2-ethylpropanediol, 2-methyl-1,8-octanediol, neopentyl glycol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydroquinone, resorcin, bisphenol-A, bisphenol-F, and 4,4'-biphenol; polyether polyols, such as polyethylene glycol, polypropylene glycol, and polytetramethylene glycol; and polyester polyols, such as polyhexamethylene adipate, polyhexamethylene succinate, and polycaprolactone.

[0056] As the polycarbonate polyol, it is preferable to use one obtained by reacting dimethyl carbonate with 1,6-hexanediol.

[0057] As the polycarbonate polyol, it is preferable to use one having a number average molecular weight in the range of 500 to 6,000.

[0058] Examples of the polyester polyol that can be used include aliphatic polyester polyols and aromatic polyester polyols obtained by an esterification reaction between a low-molecular-weight polyol and a polycarboxylic acid, polyesters obtained by a ring-opening polymerization reaction of a cyclic ester compound such as ε-caprolactone, and copolymer polyesters thereof.

[0059] Examples of low molecular weight polyols include ethylene glycol and propylene glycol.

[0060] As the polycarboxylic acid, for example, succinic acid, adipic acid, sebacic acid, dodecanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, and anhydrides or ester-forming derivatives thereof can be used.

[0061] Other polyols that can be used in combination with the hydrophilic group-containing polyol include, for example, aliphatic cyclic structure-containing polyols such as cyclohexanediol and aromatic cyclic structure-containing polyols, which may be used in combination with the various polyols described above.

[0062] Examples of polyisocyanates that can be used in producing the (a1) hydrophilic group-containing polyurethane include aromatic diisocyanates such as phenylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and naphthalene diisocyanate; and aliphatic or alicyclic structure-containing diisocyanates such as hexamethylene diisocyanate, lysine diisocyanate, cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate.

[0063] The (a1) hydrophilic group-containing polyurethane may have further functional groups in addition to the hydrophilic groups, if necessary, such as hydrolyzable silyl groups, silanol groups, amino groups, imino groups, hydroxyl groups, etc., which are capable of reacting with the (a3) ​​polysiloxane described below.

[0064] The hydrolyzable silyl group is a functional group in which a hydrolyzable group is directly bonded to a silicon atom, and is, for example, a group represented by the general formula (I): [ka] Examples of the functional group include those represented by the following formula:

[0065] In general formula (I), R 1 is a monovalent organic group such as an alkyl group, an aryl group, or an aralkyl group, and R 2 represents a halogen atom, an alkoxy group, an acyloxy group, a phenoxy group, an aryloxy group, a mercapto group, an amino group, an amido group, an aminooxy group, an iminoxy group or an alkenyloxy group, and x is an integer of 0 to 2.

[0066] Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a neopentyl group, a 1-methylbutyl group, a 2-methylbutyl group, a hexyl group, and an isohexyl group.

[0067] Examples of the aryl group include a phenyl group, a naphthyl group, and a 2-methylphenyl group.

[0068] Examples of the aralkyl group include a benzyl group, a diphenylmethyl group, and a naphthylmethyl group.

[0069] Examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.

[0070] Examples of the alkoxy group include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, and a butoxy group.

[0071] Examples of acyloxy groups include acetoxy, propanoyloxy, butanoyloxy, phenylacetoxy, and acetoacetoxy.

[0072] Aryloxy groups include, for example, phenyloxy, naphthyloxy, and the like.

[0073] Examples of the alkenyloxy group include an allyloxy group, a 1-propenyloxy group, and an isopropenyloxy group.

[0074] R in general formula (I) 2 is a general formula R 2 It is preferable that each of them is independently an alkoxy group, since it is easy to remove the eliminated component such as OH.

[0075] The silanol group is a hydroxyl group (SiOH group) bonded to a silicon atom, and is a functional group generated mainly by hydrolysis of a hydrolyzable silyl group contained in the hydrophilic group-containing polyurethane (a1).

[0076] With respect to the (a1) hydrophilic group-containing polyurethane, the total amount of hydrolyzable silyl groups and silanol groups is preferably 10 to 400 mmol / kg relative to the (a1) hydrophilic group-containing polyurethane.

[0077] The (a2) vinyl polymer preferably has a number average molecular weight of 3,000 to 100,000.

[0078] As the (a2) vinyl polymer, for example, those produced by polymerizing various vinyl monomers in the presence of a polymerization initiator can be used.

[0079] As the vinyl monomer usable for producing the vinyl polymer (a2), it is preferable to use a hydrolyzable silyl group-containing vinyl monomer, a hydroxyl group-containing vinyl monomer, or the like, from the viewpoint of introducing a functional group capable of reacting with a hydrolyzable silyl group, etc. of the polysiloxane (a3) ​​into the vinyl polymer (a2).

[0080] Examples of the hydrolyzable silyl group-containing vinyl monomer include 3-(meth)acryloyloxypropyltrimethoxysilane, 3-(meth)acryloyloxypropyltriethoxysilane, and 3-(meth)acryloyloxypropylmethyldimethoxysilane.

[0081] Examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, polyethylene glycol mono(meth)acrylate, and glycerol mono(meth)acrylate.

[0082] As the vinyl monomer, in addition to the hydrolyzable silyl group-containing vinyl monomer and the hydroxyl group-containing vinyl monomer, other vinyl monomers may be used in combination.

[0083] Examples of vinyl monomers other than the hydrolyzable silyl group-containing vinyl monomer and the hydroxyl group-containing vinyl monomer include (meth)acrylic acid esters such as methyl (meth)acrylate, ethyl (meth)acrylate, and n-butyl (meth)acrylate; tertiary amino group-containing vinyl monomers such as N,N-dimethylaminoethyl (meth)acrylate; secondary amino group-containing vinyl monomers such as N-methylaminoethyl (meth)acrylate; basic nitrogen atom-containing group-containing vinyl monomers such as primary amino group-containing vinyl monomers such as aminomethyl acrylate; fluorine-containing vinyl monomers such as 2,2,2-trifluoroethyl (meth)acrylate; vinyl esters such as vinyl acetate; vinyl ethers such as methyl vinyl ether; nitriles of unsaturated carboxylic acids such as (meth)acrylonitrile; vinyl compounds having an aromatic ring such as styrene; α-olefins such as isoprene; acrylate and the like; amide group-containing vinyl monomers such as (meth)acrylamide; methylol amide group and alkoxylated vinyl monomers such as N-methylol (meth)acrylamide; aziridinyl group-containing vinyl monomers such as 2-aziridinylethyl (meth)acrylate; isocyanate group and / or blocked isocyanate group-containing vinyl monomers such as (meth)acryloyl isocyanate; oxazoline group-containing vinyl monomers such as 2-isopropenyl-2-oxazoline; cyclopentenyl group-containing vinyl monomers such as dicyclopentenyl (meth)acrylate; carbonyl group-containing vinyl monomers such as acrolein; acetoacetyl group-containing vinyl monomers such as acetoacetoxyethyl (meth)acrylate; and carboxyl group-containing monomers such as (meth)acrylic acid, maleic acid, or half esters thereof or salts thereof.

[0084] (a2) Polymerization initiators that can be used in the production of vinyl polymers include, for example, radical polymerization initiators such as persulfates, organic peroxides, and hydrogen peroxide, and azo initiators such as 4,4'-azobis(4-cyanovaleric acid), 2,2'-azobis(2-amidinopropane) dihydrochloride, etc. The radical polymerization initiators may also be used as redox polymerization initiators in combination with reducing agents such as ascorbic acid.

[0085] Examples of persulfates, which are typical polymerization initiators, include potassium persulfate, sodium persulfate, and ammonium persulfate. Examples of organic peroxides include diacyl peroxides such as benzoyl peroxide, lauroyl peroxide, and decanoyl peroxide, dialkyl peroxides such as t-butylcumyl peroxide and dicumyl peroxide, peroxy esters such as t-butyl peroxylaurate and t-butyl peroxybenzoate, and hydroperoxides such as cumene hydroperoxide, paramenthane hydroperoxide, and t-butyl hydroperoxide.

[0086] The amount of the polymerization initiator used is preferably 10% by mass or less based on the total amount of vinyl monomers used in the production of the vinyl polymer (a2).

[0087] (a3) Polysiloxane has a chain and / or network structure composed of silicon atoms and oxygen atoms, and optionally has hydrolyzable silyl groups, silanol groups, and the like.

[0088] The hydrolyzable silyl group is an atomic group in which a hydrolyzable group is directly bonded to a silicon atom, and examples thereof include the functional group represented by general formula (I) described in the description of (a1) hydrophilic group-containing polyurethane.

[0089] Examples of the hydrolyzable group include a halogen atom, an alkoxy group, a substituted alkoxy group, an acyloxy group, a phenoxy group, a mercapto group, an amino group, an amido group, an aminooxy group, an iminoxy group, and an alkenyloxy group. Of these, an alkoxy group or a substituted alkoxy group is preferable.

[0090] The silanol group is a hydroxyl group (SiOH group) bonded to a silicon atom, and is a functional group generated mainly by hydrolysis of a hydrolyzable silyl group contained in the (a3) ​​polysiloxane.

[0091] The (a3) ​​polysiloxane may have an alkyl group such as a methyl group, a phenyl group, etc. For example, the (a3) ​​polysiloxane may have one or more selected from the group consisting of an aromatic cyclic structure such as a phenyl group, an alkyl group having 1 to 3 carbon atoms, and an alkoxy group having 1 to 3 carbon atoms directly bonded to a silicon atom constituting the polysiloxane.

[0092] As the (a3) ​​polysiloxane, for example, one obtained by completely or partially hydrolyzing and condensing a silane compound can be used.

[0093] (a3) Examples of silane compounds that can be used in the production of polysiloxane include organotrialkoxysilanes such as methyltrimethoxysilane, methyltriethoxysilane, methyltri-n-butoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, iso-butyltrimethoxysilane, cyclohexyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, vinyltrimethoxysilane, and 3-(meth)acryloyloxypropyltrimethoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, and the like. Examples of the silane include diorganodialkoxysilanes such as dimethyldi-n-butoxysilane, diethyldimethoxysilane, diphenyldimethoxysilane, methylcyclohexyldimethoxysilane, and methylphenyldimethoxysilane; and chlorosilanes such as methyltrichlorosilane, ethyltrichlorosilane, phenyltrichlorosilane, vinyltrichlorosilane, 3-(meth)acryloyloxypropyltrichlorosilane, dimethyldichlorosilane, diethyldichlorosilane, and diphenyldichlorosilane, as well as partial hydrolysis and condensation products thereof.

[0094] (a3) Polysiloxanes include those represented by the general formula (II): [ka] and the structure represented by general formula (III): [ka] It is preferable that the polysiloxane having one or more structures selected from the group consisting of structures represented by the following formulas is bonded to a condensate of an alkyltrialkoxysilane having an alkyl group with 1 to 3 carbon atoms via a bond between a silicon atom and an oxygen atom. In this specification, a polysiloxane having a structure represented by general formula (II) and / or (III) is sometimes referred to as a (a3-1) polysiloxane, and a condensate of an alkyltrialkoxysilane having an alkyl group with 1 to 3 carbon atoms is sometimes referred to as a (a3-2) condensate.

[0095] In general formula (II), R 1 is an organic group having 4 to 12 carbon atoms. 2 and R 3 are each independently a methyl group or an ethyl group.

[0096] The (a3-1) polysiloxane may be an organoalkoxysilane, preferably a monoorganotrialkoxysilane having an organic group with 4 to 12 carbon atoms bonded to a silicon atom, a diorganodialkoxysilane having two methyl groups bonded to a silicon atom, and / or a diorganodialkoxysilane having two ethyl groups bonded to a silicon atom, which has been subjected to hydrolysis and condensation. The (a3-1) polysiloxane may have any of a linear, branched, or cyclic structure.

[0097] Examples of the organic group having 4 to 12 carbon atoms include an alkyl group, a cycloalkyl group, an aryl group, and an aralkyl group having 4 to 12 carbon atoms. For example, alkyl groups such as an n-butyl group, an iso-butyl group, an n-hexyl group, an n-octyl group, an n-dodecyl group, and a cyclohexylmethyl group; cycloalkyl groups such as a cyclohexyl group and a 4-methylcyclohexyl group; aryl groups such as a phenyl group and a 4-methylphenyl group; and aralkyl groups such as a benzyl group are preferred, and among these, a phenyl group or an alkyl group having 4 carbon atoms is more preferred.

[0098] As the (a3-2) condensation product, for example, one having a hydroxyl group bonded to a silicon atom (that is, a silanol group) and an alkoxy group bonded to a silicon atom can be used.

[0099] As the (a3-2) condensation product, a product represented by the general formula (IV): [ka] It is preferable to use a compound having a structure represented by the following formula:

[0100] In general formula (IV), R 4 is an alkyl group having 1 to 3 carbon atoms.

[0101] (a) A method for producing a composite resin includes, for example, the following steps (1) to (3).

[0102] Step (1) is a step of polymerizing a vinyl monomer in an organic solvent in the presence of a polymerization initiator to obtain (a2) an organic solvent solution of a vinyl polymer.

[0103] The polymerization is preferably carried out, for example, by gradually or all at once supplying the vinyl monomer to an organic solvent containing a polymerization initiator, and then stirring the mixture at a temperature in the range of 20 to 120° C. for about 0.5 to 24 hours.

[0104] Step (2) is a step of obtaining an organic solvent solution of a resin formed by bonding (a2) vinyl polymer and (a3) ​​polysiloxane by carrying out a reaction between a reactive functional group such as a hydrolyzable silyl group of (a2) vinyl polymer and a hydrolyzable silyl group or a silanol group of a silane compound in an organic solvent solution of the (a2) vinyl polymer obtained in step (1) and a hydrolysis condensation reaction between the silane compounds.In this specification, the resin formed by bonding (a2) vinyl polymer and (a3) ​​polysiloxane may be referred to as (a4) resin.

[0105] The reaction in step (2) can be carried out continuously from step (1), for example, by gradually or all at once supplying (a3) ​​a silane compound capable of forming a polysiloxane to an organic solvent solution of (a2) the vinyl polymer obtained in step (1), and then carrying out the reaction under stirring at a temperature range of 20 to 120°C for about 0.5 to 24 hours.

[0106] Moreover, the step (2) preferably involves a two-stage reaction process. Specifically, the step (2) preferably includes (a2) a process of reacting a hydrolyzable silyl group or silanol group of the vinyl polymer with a relatively low molecular weight silane compound such as phenyltrimethoxysilane, and then a process of reacting the product obtained in the process with a condensate obtained by previously condensing a methyltrialkoxysilane and an ethyltrialkoxysilane such as methyltrimethoxysilane and ethyltrimethoxysilane.

[0107] Step (3) is a step of mixing the (a4) resin obtained in step (2) with the (a1) hydrophilic group-containing polyurethane and hydrolyzing and condensing the resulting mixture to obtain an organic solvent solution of the (a) composite resin, i.e., a composite resin in which the hydrophilic group-containing polyurethane and the vinyl polymer are bonded via polysiloxane.

[0108] The hydrolysis condensation reaction in step (3) can be carried out continuously from step (2), for example. It is preferable to gradually or all at once supply (a1) hydrophilic group-containing polyurethane obtained by reacting a polyol containing a hydrophilic group-containing polyol with a polyisocyanate into an organic solvent solution of the (a4) resin obtained in step (2), and then carry out the reaction at a temperature in the range of 20 to 120°C for about 0.5 to 24 hours under stirring.

[0109] (a) The method for producing a composite resin may further include the following step (4):

[0110] Step (4) is a step of making the organic solvent solution of the (a) composite resin obtained in step (3) aqueous. Step (4) can be performed, for example, consecutively from step (3), and is a step of neutralizing the hydrophilic groups of the (a) composite resin in the organic solvent solution of the (a) composite resin, and dispersing or dissolving the neutralized (a) composite resin in an aqueous medium.

[0111] The neutralization in step (4) can be carried out, for example, by gradually or all at once supplying a basic compound or the like to the organic solvent solution of the (a) composite resin and stirring the mixture. Next, an aqueous medium is supplied to the organic solvent solution of the neutralized (a) composite resin, and then the organic solvent can be removed. The organic solvent can be removed, for example, by distillation.

[0112] Examples of the aqueous medium include water, organic solvents miscible with water, and mixtures thereof. Examples of the organic solvent miscible with water include alcohols such as methanol, ethanol, n-propanol, and isopropanol; ketones such as acetone and methyl ethyl ketone; polyalkylene glycols such as ethylene glycol, diethylene glycol, and propylene glycol; alkyl ethers of polyalkylene glycol; and lactams such as N-methyl-2-pyrrolidone.

[0113] In the coating composition of the present invention, the amount of the resin having a silanol group (A-1) in the coating film-forming components is preferably 20 to 98 mass %. The resin having a silanol group (A-1) may be used alone or in combination of two or more kinds.

[0114] In the coating composition of the present invention, the amount of the composite resin (a) in the coating film-forming components is preferably 20 to 98 mass %. The composite resin (a) may be used alone or in combination of two or more kinds.

[0115] In this specification, the film-forming component refers to the components excluding volatile components such as solvents, and is the component that will ultimately form a coating film, but in the present invention, the components remaining when the coating composition is dried at 130°C for 60 minutes are treated as the film-forming component. In this specification, the components excluding volatile components such as solvents, and that will ultimately form a coating film, are sometimes referred to as "non-volatile components". In the coating composition of the present invention, the amount of the film-forming component is preferably 30 to 80 mass%.

[0116] (B) The curing agent is (B-1) represented by the general formula: Si(OR) 4 [wherein R are the same or different and are organic groups having 1 to 8 carbon atoms] and / or a partial condensate of the organosilicate. By using component (B-1) as a curing agent for component (A-1), it is possible to improve adhesion to surfaces on which a photocatalyst is present, inorganic substrates, and inorganic coating films.

[0117] The (B-1) component preferably contains a silane compound (i.e., an organosilicate and / or a partial condensate of an organosilicate) having a molecular weight in the range of 200 to 3,000, and more preferably contains a silane compound having a molecular weight in the range of 200 to 1,500. By using a silane compound having a molecular weight in the range of 200 to 3,000, it is possible to further improve adhesion to surfaces on which a photocatalyst is present, inorganic substrates, and inorganic coating films. In the coating composition of the present invention, the amount of the (B-1) component having a molecular weight in the range of 200 to 3,000 in the coating film-forming components is preferably 2 to 7% by weight.

[0118] General formula: Si(OR) 4In the formula, R are the same or different and are organic groups having 1 to 8 carbon atoms. Examples of the organic group having 1 to 8 carbon atoms include alkyl groups, cycloalkyl groups, aryl groups, and aralkyl groups, such as alkyl groups such as methyl, ethyl, n-propyl, isopropyl, n-butyl, iso-butyl, n-hexyl, n-octyl, and cyclohexylmethyl groups; cycloalkyl groups such as cyclohexyl and 4-methylcyclohexyl groups; aryl groups such as phenyl and 4-methylphenyl groups; and aralkyl groups such as benzyl groups.

[0119] General formula: Si(OR) 4 Examples of the organosilicate represented by the formula (1) include tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetra-i-propoxysilane, tetra-n-butoxysilane, tetra-i-butoxysilane, and tetra-t-butoxysilane.

[0120] Since organosilicates have low miscibility in emulsions, they are preferably used in combination with a surfactant.

[0121] General formula: Si(OR) 4 The partial condensate of the organosilicate represented by the formula (I) is mainly a partial hydrolysis condensate of the organosilicate.

[0122] In the coating composition of the present invention, the amount of component (B-1) in the coating film-forming components is preferably 2 to 10 mass %. The component (B-1) may be used alone or in combination of two or more.

[0123] The (B) curing agent may contain an additional silane compound in addition to the (B-1) component. The additional compound is preferably a compound having an alkoxysilyl group, and more preferably contains at least one silane compound selected from the group consisting of the silane compounds (B-2) to (B-5) described below. The silane compounds (B-2) to (B-5) are preferably silane compounds having a molecular weight in the range of 200 to 3,000. Silane Compound (B-2) The silane compound (B-2) is a ketoimino group-containing alkoxysilane compound. Silane Compound (B-3) The silane compound (B-3) is an amino group-containing alkoxysilane compound. Silane Compounds (B-4) The silane compound (B-4) is an epoxy group-containing alkoxysilane compound. Silane Compounds (B-5) The silane compound (B-5) is an isocyanate group-containing alkoxysilane compound.

[0124] The silane compound (B-2) is a ketoimino group-containing alkoxysilane compound. The ketoimino group-containing alkoxysilane compound is a compound having a ketoimino group and an alkoxysilyl group, which is formed by reacting a primary amino group in the molecule with a ketone. For example, 3-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine and 3-trimethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine are listed. Examples of commercially available products of these include KBE-9103 manufactured by Shin-Etsu Chemical Co., Ltd., Saraace S340 manufactured by Chisso Corporation, and Z-6860 manufactured by Dow Corning Toray Co., Ltd.

[0125] The silane compound (B-3) is an amino group-containing alkoxysilane compound. Specific examples of the amino group-containing alkoxysilane compound include γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltriisopropoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β-(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriethoxysilane, N Examples of such silane include N-β-(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-β-(aminoethyl)-γ-aminopropyltriisopropoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, and N-β-(aminoethyl)-8-aminooctyltrimethoxysilane.

[0126] Silane compound (B-4) is an epoxy group-containing alkoxysilane compound.Specific examples of epoxy group-containing alkoxysilane compounds include glycidoxymethyl trimethoxysilane, glycidoxymethyl triethoxysilane, β-glycidoxyethyl trimethoxysilane, β-glycidoxyethyl triethoxysilane, γ-glycidoxypropyl trimethoxysilane, γ-glycidoxypropyl triethoxysilane, γ-glycidoxypropyl methyl dimethoxysilane, γ-glycidoxypropyl methyl diethoxysilane, γ-glycidoxypropyl dimethyl methoxysilane, γ-glycidoxypropyl (ethyl) dimethoxysilane, β-3,4-epoxycyclohexyl ethyl trimethoxysilane, β-3,4-epoxycyclohexyl ethyl triethoxysilane, 8-glycidoxyoctyl trimethoxysilane, 8-glycidoxyoctyl methyl dimethoxysilane, 8-glycidoxyoctyl methyl diethoxysilane, etc.

[0127] The silane compound (B-5) is an isocyanate group-containing alkoxysilane compound. Specific examples of the isocyanate group-containing alkoxysilane compound include 3-isocyanatepropyltriethoxysilane.

[0128] In the coating composition of the present invention, the amount of the additional silane compound in the coating film-forming components is preferably 2 to 10 mass %. The additional silane compound may be used alone or in combination of two or more.

[0129] The coating composition of the present invention preferably contains a substance that accelerates the hydrolysis and condensation of alkoxysilyl groups. The substance that accelerates the hydrolysis and condensation of alkoxysilyl groups may be contained in either the base agent or the curing agent, but is preferably contained in the curing agent. As the substance that accelerates the hydrolysis and condensation of alkoxysilyl groups, an organometallic compound, an acid catalyst, or a basic catalyst is used. In particular, an organotin compound is preferable.

[0130] Specific examples of organotin compounds include dibutyltin dilaurate, dibutyltin dimaleate, dibutyltin dioleylmaleate, dioctyltin dilaurate, dibutyltin diacetate, dibutyltin dimethoxide, dibutyltin thioglycolate, dibutyltin bisisononyl 3-mercaptopropionate, dibutyltin bisisooctylthioglycolate, dibutyltin bis2-ethylhexylthioglycolate, dimethyltin bisdodecyl mercaptide, dibutyltin bisdodecyl mercaptide, dioctyltin bisdodecyl mercaptide, dibutyltin bislauryl mercaptide, dimethyltin bis(octylthioglycolate) salt, and tin octylate.

[0131] Among these, from the viewpoint of stability in water, mercaptide-based compounds such as dibutyltin thioglycolate, dibutyltin bisisononyl 3-mercaptopropionate, dibutyltin bisisooctylthioglycolate, dibutyltin bis2-ethylhexyl thioglycolate, dimethyltin bisdodecyl mercaptide, dibutyltin bisdodecyl mercaptide, dioctyltin bisdodecyl mercaptide, dibutyltin bislauryl mercaptide, and dimethyltin bis(octylthioglycolate) salts are preferred.

[0132] It is preferable to use a substance that accelerates the hydrolysis and condensation of alkoxysilyl groups in combination with a surfactant.

[0133] In the coating composition of the present invention, the amount of the substance that accelerates the hydrolysis and condensation of the alkoxysilyl group in the coating film-forming components is preferably 0.01 to 10% by mass. The substance that accelerates the hydrolysis and condensation of the alkoxysilyl group may be used alone or in combination of two or more kinds.

[0134] The coating composition of the present invention preferably contains an ultraviolet absorbing agent. The ultraviolet absorbing agent has the effect of absorbing ultraviolet rays and preventing deterioration caused by ultraviolet rays. By using the ultraviolet absorbing agent, the weather resistance of the coating film can be improved. The ultraviolet absorbing agent may be contained in either the base agent or the curing agent, but it is preferable that the ultraviolet absorbing agent is contained in the base agent.

[0135] Examples of the ultraviolet absorbent include benzophenone-based ultraviolet absorbents, benzoate-based ultraviolet absorbents, benzotriazole-based ultraviolet absorbents, triazine-based ultraviolet absorbents (particularly hydroxyphenyltriazine-based ultraviolet absorbents), and benzylidene camphor-based ultraviolet absorbents. The ultraviolet absorbent may be used alone or in combination of two or more kinds, but it is preferable that the ultraviolet absorbent contains two or more kinds of ultraviolet absorbents with different absorption peaks. The ultraviolet absorbent preferably contains a triazine-based ultraviolet absorbent, and particularly preferably contains a triazine-based ultraviolet absorbent and a benzotriazole-based ultraviolet absorbent.

[0136] Examples of the ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone-2-hydroxy-4-benzyloxybenzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4, 4'-Dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-(dimethylbenzyl)phenyl]benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzo Triazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2,2'-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-(2N-benzotriazol-2-yl)phenol], methyl-3-[3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]phenol, 2-(2-hydroxyphenyl)propionate and polyethylene glycol condensation products, 2-(2-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,6-di-t-butylphenyl-3',5'-di-t-butyl-4'-hydroxybenzoate, hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate, 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butyloxyphenyl)-6-(2,4-bis-butyloxyphenyl)-1,3,5-triazine, hydroxyphenyl triazine, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine, and the like.

[0137] In the coating composition of the present invention, the amount of the ultraviolet absorber in the coating film-forming components is, for example, 0 to 9 mass %.

[0138] The coating composition of the present invention preferably contains a radical scavenger. The radical scavenger can capture free radicals and improve light stability. In the present invention, the radical scavenger also includes a substance (so-called polymerization inhibitor) that reacts with free radicals and has the function of preventing polymerization reaction from occurring. The use of the radical scavenger can improve the weather resistance of the coating film. The radical scavenger may be contained in either the base agent or the curing agent, but is preferably contained in the base agent.

[0139] Examples of the radical scavenger include hindered amine compounds, hydroquinone compounds, phenol compounds, phenothiazine compounds, nitroso compounds, and N-oxyl compounds, and hindered amine light stabilizers (HALS) are particularly preferred.

[0140] Examples of the radical scavenger include hindered amine compounds such as bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, 1-{2-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)ethyl}-2,2,6,6-tetramethylpiperidine, and 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro{4.5}decane-2,4-dione; phenols; and o-, m-, or p-cresols. phenolic compounds such as 2-t-butyl-4-methylphenol, 6-t-butyl-2,4-dimethylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4-t-butyl-2,6-dimethylphenol, hydroquinone, hydroquinone monomethyl ether, methylhydroquinone, 2,5-di-t-butyl Hydroquinone compounds such as 4-methylbenzcatechin, t-butylhydroquinone, 3-methylbenzcatechin, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, benzoquinone, t-butyl-p-benzoquinone, and 2,5-diphenyl-p-benzoquinone; phenothiazine compounds; nitroso-based compounds such as N-nitroso-N-phenylhydroxylamine ammonium and N-nitroso-N-phenylhydroxylamine aluminum salt; and N-oxyl-based compounds such as 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, and 4-methoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl.

[0141] In the coating composition of the present invention, the amount of the radical scavenger in the coating film-forming components is, for example, 0 to 7% by mass. The radical scavengers may be used alone or in combination of two or more.

[0142] The coating composition of the present invention may contain a surfactant. The surfactant is a substance having a hydrophilic group and a hydrophobic group in the molecule, and is a substance capable of dispersing a silane compound such as component (B-1) or a substance that promotes hydrolysis and condensation of an alkoxysilyl group in water. The surfactant is used in the base agent and / or the curing agent as necessary. The surfactant is classified into anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. The amount of the surfactant in the coating composition of the present invention is preferably 10% by mass or less, more preferably 0.2 to 8% by mass. The surfactant may be used alone or in combination of two or more kinds.

[0143] The coating composition of the present invention is preferably a clear coating that does not contain a pigment, but may contain pigments such as color pigments, extender pigments, metallic pigments, glitter pigments, and scale-like pigments. The pigment may be contained in either the base agent or the curing agent, but is preferably contained in the base agent. Examples of color pigments include inorganic pigments such as titanium dioxide, iron oxide, and carbon black, and organic pigments such as phthalocyanine pigments and azo pigments. Examples of extender pigments include silica, talc, mica, calcium carbonate, barium sulfate, and clay. Other pigments include aluminum powder pigments, nickel powder pigments, gold powder, silver powder, bronze powder, copper powder, stainless steel powder pigments, mica pigments, graphite pigments, glass flake pigments, metal-coated glass powders, metal-coated mica powders, metal-coated plastic powders, and scale-like iron oxide pigments.

[0144] In the coating composition of the present invention, the amount of pigment in the coating film-forming components is preferably 30 mass % or less. The pigments may be used alone or in combination of two or more kinds.

[0145] The coating composition of the present invention is preferably an aqueous coating composition. In this specification, an aqueous coating composition is a coating composition containing water as a main solvent. The water used in the coating composition is not particularly limited, and preferably includes pure water such as ion-exchanged water and distilled water, but may be groundwater or tap water. In addition, when the coating composition is stored for a long period of time, water sterilized by ultraviolet irradiation or the like may be used to prevent the growth of mold and bacteria. In the coating composition of the present invention, the amount of water is preferably 20 to 70% by mass. In addition, the coating composition of the present invention can be made completely aqueous, and the ratio of water in the solvent used is preferably 85% by mass or more, and most preferably 100% by mass.

[0146] The coating composition of the present invention may contain other components, such as other resins, crosslinking agents, film-forming aids, antifreezing agents, surface conditioners, wetting agents, dispersants, defoamers, viscosity adjusters, thickeners, antisettling agents, antiskinning agents, antisagging agents, color separation inhibitors, matting agents, adhesion imparting agents, leveling agents, drying agents, plasticizers, antifungal agents, antibacterial agents, antiviral agents, preservatives, insecticides, antistatic agents, and conductivity imparting agents, as appropriate, depending on the purpose. Commercially available products may be suitably used for these components.

[0147] In the present invention, the base agent and the curing agent are prepared in advance, and the coating composition can be prepared by mixing them at the time of painting. Also, additives may be prepared separately from the base agent and the curing agent, and the additives may be further added when the base agent and the curing agent are mixed. For example, water or a diluent can be further added as an additive for the purpose of adjusting the viscosity. Also, the base agent and the curing agent can be prepared by mixing various components appropriately selected as necessary.

[0148] The coating composition of the present invention is preferably a clear coating. In this specification, the clear coating is a coating that forms a transparent coating film, and when a film of 30 μm thickness is formed, the visible light transmittance is 60% or more, preferably 80% or more, more preferably 90% or more, and even more preferably 95% or more.

[0149] The coating composition of the present invention preferably has a visible light transmittance of 20% or more when a film having a thickness of 30 μm is formed, more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, and most preferably 100%.

[0150] The visible light transmittance means the total light transmittance in the visible region (360 nm to 750 nm), and can be measured in accordance with JIS K 7375:2008.

[0151] The coating composition of the present invention preferably has an ultraviolet ray transmittance of 20% or less, more preferably 10% or less, and most preferably 0% when a film having a thickness of 30 μm is formed.

[0152] In this specification, the ultraviolet transmittance means the transmittance of light in the wavelength range of 300 nm to 350 nm, and can be measured using a spectrophotometer.

[0153] The coating composition of the present invention has a viscosity of 1 to 1000 (Pa s, 23°C) at a shear rate of 0.1 (1 / s), and preferably has a viscosity of 0.05 to 10 (Pa s, 23°C) at a shear rate of 1000 (1 / s). In this specification, the viscosity is measured using a rheometer (for example, ARES rheometer manufactured by TA Instruments) after adjusting the liquid temperature to 23°C.

[0154] The means for applying the coating composition of the present invention is not particularly limited, and known coating means such as brush coating, roller coating, trowel coating, spatula coating, flow coater coating, and spray coating (e.g., air spray coating, airless spray coating), can be used.

[0155] The means for drying the coating composition of the present invention is not particularly limited, and may be either natural drying at ambient temperature or forced drying using a dryer or the like.

[0156] Regarding the coating film formed from the coating composition of the present invention, the silicon content in the resin constituting the coating film is 5.0 to 15.0% by mass, preferably 5.0 to 12.0% by mass, and more preferably 6.0 to 10.0% by mass. If the silicon content in the resin constituting the coating film is 5.0% by mass or more, the resistance to photocatalytic activity is improved and weather resistance can be improved. On the other hand, if the silicon content in the resin constituting the coating film is too high, the coating film becomes glassy and there is a problem of reduced frost resistance, so the silicon content in the resin constituting the coating film is preferably 15.0% by mass or less.

[0157] Since the coating composition of the present invention contains a base agent and a curing agent, the resin constituting the coating film is a resin formed by a curing reaction between a reactive component contained in the base agent (e.g., component (A-1)) and a reactive component contained in the curing agent (e.g., component (B-1)). In addition, when a non-reactive resin is contained in the coating composition, the non-reactive resin also corresponds to the resin constituting the coating film.

[0158] In this specification, the silicon content contained in the resin constituting the coating film can be determined as follows. (0) The sample shall be the film-forming component or, if pigment is present, the film-forming component from which the pigment has been removed. (i) Weigh out 3 g of sample into a magnetic crucible of known mass at constant weight. (ii) The sample in the porcelain crucible is heated at 150° C. for 30 minutes, and then further heated at 550° C. for 2 hours to incinerate the sample. (iii) Allow the ashed sample to cool to room temperature, then weigh the sample. Calculate the ash content according to the following formula: Ash content (mass%) = mass of ashed sample (g) / (mass of sample before heating (g) x resin ratio) x 100 Here, since the ash has a silicon dioxide structure, the proportion of silicon atoms can be calculated as follows: Silicon atom ratio (mass%) = ash content (mass%) × 28.1 ÷ 60.1 Since inorganic components other than silicon atoms may be included, the presence and ratio of inorganic components other than silicon atoms can be confirmed by elemental analysis such as fluorescent X-rays on the obtained ash or coating-forming components.

[0159] The coating film formed from the coating composition of the present invention has an elongation percentage at 23° C. of 15% or more, preferably 30% or more, and more preferably 50% or more. By making the elongation percentage at 23° C. of the coating film formed from the coating composition of the present invention 15% or more, the frost resistance of the coating film can be improved. In addition, the coating film formed from the coating composition of the present invention has no particular upper limit on its elongation percentage, but for example, the elongation percentage at 23° C. is 200% or less.

[0160] In this specification, the elongation of the coating film is measured as follows. A coating composition is applied to a polypropylene plate with an applicator so that the dry film thickness is 30 to 60 μm, and the coating film is formed by drying at 23° C. for 6 hours and then at 50° C. for 3 hours. The resulting coating film is then cut into strips of 10×50 mm to prepare test pieces. A tensile test is then performed under conditions of a chuck distance of 30 mm, a load of 1 kN, and a speed of 5 mm / min in a 23° C., 50% relative humidity environment, to measure the breaking elongation (%) of the test piece. The tensile test is performed five times. The minimum and maximum values ​​of the five measured values ​​are excluded, and the average value of the three measured values ​​is determined, and this is the elongation (%) of the coating film.

[0161] In the coating composition of the present invention, the use of a silanol group-containing resin (A-1) having a urethane structure can increase the elongation of the resulting coating film. The elongation of the coating film can also be increased by using a resin having a structure in which the proportion of aromatic ring structures is low and the proportion of straight-chain or ring structures other than aromatic rings is high, by reducing the crosslink density when the resin constituting the coating film contains a crosslinked structure, by adding a plasticizer, and by reducing the silicon content in the coating film.

[0162] The dry film thickness of the coating film formed from the coating composition of the present invention is preferably 10 to 50 μm. In this specification, the dry film thickness is also referred to as the coating film thickness.

[0163] The coating composition of the present invention is preferably a sealer (undercoat coating). However, it is not limited thereto, and the coating composition of the present invention can be applied over and over again. For example, the coating composition of the present invention can be used as both an undercoat and a topcoat coating, and applied twice. When the coating composition of the present invention is used as an undercoat coating, the topcoat coating can be a clear coating or a colored, opaque coating.

[0164] The coating composition of the present invention is preferably a coating material for repair, and particularly preferably a coating material for repairing exterior building materials.

[0165] Examples of coating methods using the coating composition of the present invention include a method in which the coating composition of the present invention is applied to a substrate as an undercoat paint, and then a topcoat paint (e.g., a clear topcoat paint or a colored opaque paint), a method in which the coating composition of the present invention is applied to a substrate as an undercoat paint, and then an intermediate coat paint for designing is applied, and then a clear topcoat paint is applied, and a method in which the coating composition of the present invention is applied to a substrate as both an undercoat paint and a topcoat paint, etc. In addition, when the coating composition of the present invention is applied, an old coating film may be present on the substrate.

[0166] In this specification, the term "old coating film" refers to a coating film that is already present on a substrate when painting, particularly repair, is performed. Since the coating composition of the present invention can form a coating film that has excellent adhesion to a surface on which a photocatalyst is present or to an inorganic coating film, when an old coating film is present, it is preferable that the old coating film is a coating film containing a photocatalyst or an inorganic coating film.

[0167] Examples of the substrate include plastic substrates such as epoxy resin, ABS resin, polycarbonate, polyvinyl chloride, polystyrene, acrylic resin, for example, polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), polyolefin, for example, polypropylene (PP), etc., metal substrates such as steel, galvanized steel, tinned steel, stainless steel, magnesium alloy, aluminum, aluminum alloy, titanium, titanium alloy, etc., inorganic substrates other than metals such as cement, mortar, concrete, slate, gypsum, calcium silicate, glass, ceramic, calcium carbonate, marble, artificial marble, etc., wood substrates such as wood, etc., composite substrates in which two or more of these substrates are combined, etc. Examples of the composite substrates include composite substrates such as wood fiber reinforced cement boards, fiber reinforced cement boards, fiber reinforced cement-calcium silicate boards, metal substrates that have been subjected to various surface treatments, for example, oxidation treatments, plastic substrates whose surfaces are coated with inorganic substances (for example, plastic substrates coated with glass), etc.

[0168] Since the coating composition of the present invention is capable of forming a coating film that has excellent adhesion to inorganic substrates, the substrate to be coated is preferably an inorganic substrate.

[0169] The substrate may have various shapes, for example, a plate-like substrate, etc. The surface of the substrate may be smooth or may have irregularities.

[0170] Specific examples of the substrate include structures such as buildings and structures, vehicles (automobiles, etc.), furniture, fittings, electronic devices (home appliances, etc.), and parts thereof. In the present invention, a building means a structure built for the purpose of human habitation or stay, such as a house (particularly a detached house or an apartment building), a building, or a factory, and a structure means a structure built for purposes other than human habitation or stay, such as a bridge, a tank, a plant piping, or a chimney. In addition, examples of structural members include a roof or a wall (such as an inner wall or an outer wall, particularly a curtain wall).

[0171] Since the coating composition of the present invention is capable of forming a coating film that is excellent in weather resistance and frost resistance, it is preferably applied to exterior substrates of structures such as buildings.

[0172] The substrate is preferably a building material, particularly a building board. Specific examples of the building substrate include wood building materials such as veneer, plywood, particle board, and medium density fiberboard (MDF); ceramic building materials such as ceramic siding board, flexible board, calcium silicate board, gypsum slag barite board, wood chip cement board, asbestos cement board, pulp cement board, precast concrete board, lightweight aerated concrete (ALC) board or ALC panel, and gypsum board; various building materials (particularly building boards) such as metal building materials such as metal siding board, aluminum, iron, and stainless steel. Specific examples of the substrate include PVC sheet, tarpaulin, plastic cardboard, plastic substrates such as acrylic board, tiles, and glass plates.

[0173] The surface of the substrate may be subjected to pretreatment such as degreasing, chemical conversion treatment, and polishing, or may be coated with a sealer or primer. For example, when the substrate is a substrate (particularly a porous substrate) that may excessively absorb paint such as ceramic building materials, the surface of the substrate may be coated with a sealer and a sealer layer may be formed on the substrate. Also, when the substrate is a metal building material, the surface of the substrate may be coated with a primer and a primer layer may be formed on the substrate.

[0174] The method for repairing an architectural exterior material of the present invention is a method for repairing an architectural exterior material using the coating composition of the present invention described above. In this specification, this method may also be referred to as the "repair method of the present invention."

[0175] An architectural exterior material is a building material used for the exterior (exterior wall, roof, etc.) of a structure such as a building or a construction. For the architectural exterior material, various architectural substrates as described above are used. Since the coating composition of the present invention can form a coating film with excellent adhesion to an inorganic substrate, it is preferable that the object of repair is an inorganic substrate.

[0176] The building exterior material may have an old coating film on its surface. The old coating film covers a part or the whole of the surface of the building exterior material. In one embodiment of the repair method of the present invention, the coating composition of the present invention can be applied onto the old coating film on the surface of the building exterior material without peeling or removing the old coating film. For example, when the old coating film has a design, it is often preferable to repair the building exterior material while leaving the old coating film in order to make use of the existing design.

[0177] In the repair method of the present invention, it is preferable to remove contaminants on the old coating film without peeling or removing the old coating film on the surface of the building exterior material, and then apply the coating composition of the present invention on the old coating film. Since contaminants such as dust and dirt are attached to the old coating film of the building exterior material, the adhesion of the new coating film to the old coating film can be improved by removing the contaminants. Methods for removing contaminants include high-pressure water washing, alkaline washing with caustic soda, etc., acid washing with inorganic or organic acids, washing with bleaching agents such as perchloric acid, and washing with scraping and cloth wiping.

[0178] The old coating film preferably contains a resin, such as acrylic resin, silicone resin, acrylic silicone resin, styrene acrylic copolymer resin, polyester resin, fluororesin, rosin resin, petroleum resin, coumarone resin, phenolic resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, xylene resin, alkyd resin, aliphatic hydrocarbon resin, butyral resin, maleic acid resin, fumaric acid resin, vinyl resin, amine resin, ketimine resin, and resins modified from these resins (modified resins). The resin may be used alone or in combination of two or more. Since the coating composition of the present invention can form a coating film with excellent adhesion to inorganic coating films, the old coating film is preferably an inorganic coating film.

[0179] The old coating film may contain various additives as other components, such as photocatalysts, pigments, dispersants, surface conditioners, antioxidants, plasticizers, rust inhibitors, preservatives, antifungal agents, solvents, antibacterial agents, antiviral agents, viscosity adjusters, fillers, defoamers, charge control agents, stress relaxation agents, penetrating agents, light-guiding materials, glittering materials, magnetic materials, phosphors, ultraviolet absorbers, radical scavengers, etc. Since the coating composition of the present invention is capable of forming a coating film that has excellent adhesion to a surface on which a photocatalyst is present, it is preferable that the old coating film is a coating film that contains a photocatalyst.

[0180] In the repair method of the present invention, an undercoat coating film can be formed by applying the coating composition of the present invention, and the dry thickness of the undercoat coating film is preferably 10 to 50 μm. The coating composition of the present invention is obtained by mixing a base agent and a hardener, and when an old coating film is present, the base agent and the hardener may be mixed after removing contaminants on the old coating film.

[0181] The repair method of the present invention preferably further comprises a step of applying a topcoat paint onto the undercoat paint film formed from the paint composition of the present invention to form a topcoat paint film. The topcoat paint may be the paint composition of the present invention, or another paint composition may be used.

[0182] The topcoat paint is preferably a two-liquid or multi-component aqueous paint composition containing a base agent and a curing agent. The topcoat paint is preferably an aqueous paint using water as the main solvent. The water used in the topcoat paint is not particularly limited, and suitable examples include pure water such as ion-exchanged water and distilled water, but groundwater or tap water may also be used. When the topcoat paint is to be stored for a long period of time, water sterilized by ultraviolet irradiation or the like may be used to prevent the growth of mold or bacteria. The amount of water in the topcoat paint is preferably 20 to 70% by mass. The topcoat paint can also be completely water-based, and the proportion of water in the solvent used is preferably 85% by mass or more, and most preferably 100% by mass. The amount of the film-forming component in the topcoat paint is preferably 30 to 80% by mass.

[0183] The base material for the topcoat paint usually contains a resin, and in the present invention, it is preferable that it contains at least a water-dispersible resin containing an acrylic component. The curing agent for the topcoat paint usually contains a component for curing the resin contained in the base material, such as a curing component such as a crosslinking agent, and in the present invention, it is preferable that it contains at least one curing component selected from at least carbodiimide and isocyanate. By using a water-dispersible resin containing an acrylic component as the base material for the topcoat paint and a curing component selected from carbodiimide and isocyanate as the curing agent for the topcoat paint, the adhesion of the topcoat paint film to the undercoat paint film can be improved, the paint film strength can be improved, and good alkali resistance and contamination resistance can be achieved.

[0184] In the topcoat paint, the water-dispersible resin containing an acrylic component preferably contains an emulsion resin. The emulsion resin is a water-dispersible resin that can increase the molecular weight and has excellent dispersion stability. The acrylic component refers to acrylic acid, methacrylic acid and their derivatives (for example, compounds having a (meth)acryloyl group such as esters and amides of acrylic acid and methacrylic acid, acrylic acid nitrile, methacrylic acid nitrile, etc.). In this specification, the resin containing an acrylic component means that the resin contains an acrylic component as its structural unit (repeating unit, etc.). In addition, the resin containing an acrylic component can also be referred to as a resin containing a structural unit derived from an acrylic component. In this specification, the water-dispersible resin containing an acrylic component is also referred to as a "water-dispersible resin (X)". The water-dispersible resin (X) will be described in detail later.

[0185] In the topcoat paint, the amount of the water-dispersible resin (X) in the coating film-forming components is preferably 50 to 98 mass %. The water-dispersible resin (X) may be used alone or in combination of two or more kinds.

[0186] In the topcoat paint, the base material may further contain a resin other than the water-dispersible resin containing an acrylic component. Examples of other resins include silicone resin, polyester resin, fluororesin, rosin resin, petroleum resin, coumarone resin, phenolic resin, urethane resin, melamine resin, urea resin, epoxy resin, cellulose resin, xylene resin, alkyd resin, aliphatic hydrocarbon resin, butyral resin, maleic acid resin, fumaric acid resin, vinyl resin, amine resin, ketimine resin, and resins obtained by modifying these resins (modified resins).

[0187] In the topcoat paint, the curing agent preferably contains at least one curing component selected from carbodiimide and isocyanate. The curing components carbodiimide and isocyanate can cure the water-dispersible resin (X) by reacting with the water-dispersible resin (X). A curing system using a curing component selected from carbodiimide and isocyanate can improve the water resistance and alkali resistance of the topcoat coating film. In addition, carbodiimide is preferable as the curing component. When the substrate has unevenness such as ceramic building materials, some parts with a thick film thickness may be formed, but from the viewpoint of forming a coating film with excellent appearance on such substrates, a carbodiimide curing system is preferable. In addition, the carbodiimide is preferably a water-dispersible carbodiimide. By making it a water-dispersible type, the dispersion stability when mixed with the main agent is improved.

[0188] Examples of carbodiimides that can be used as the curing component include carbodiimide compounds such as N,N'-dicyclohexylcarbodiimide, N,N'-diisopropylcarbodiimide, 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide, N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide, N-[3-(dimethylamino)propyl]-N'-ethylcarbodiimide methiodide, N-tert-butyl-N'-ethylcarbodiimide, N-cyclohexyl-N'-(2-morpholinoethyl)carbodiimide meso-p-toluenesulfonate, N,N'-di-tert-butylcarbodiimide, and N,N'-di-p-tolylcarbodiimide; carbodiimide compounds obtained by a known condensation reaction of polyisocyanate in the presence of a carbodiimidization catalyst; and carbodiimide compounds made from polyisocyanate and polyalkylene oxide as raw materials.

[0189] Also, carbodiimide group-containing resins are known as carbodiimide that can be used as a curing component. The carbodiimide group-containing resin is preferably blended in the form of a carbodiimide group-containing resin emulsion, a carbodiimide group-containing resin dispersion, and / or a carbodiimide group-containing resin aqueous solution. In this specification, the carbodiimide group-containing resin emulsion means an emulsion in which a carbodiimide group-containing resin is dispersed in an aqueous medium mainly composed of water, and the carbodiimide group-containing resin dispersion means a dispersion in which a carbodiimide group-containing resin is dispersed in an aqueous medium mainly composed of water.

[0190] When a carbodiimide is used as the curing component, the resin is preferably a carboxyl group-containing resin.

[0191] Examples of isocyanates that can be used as the curing component include aliphatic, aromatic, or araliphatic isocyanate compounds, and are preferably compounds having two or more isocyanate groups (also called polyisocyanates). Specific examples thereof include tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, xylylene diisocyanate, hexamethylene diisocyanate, 4,4'-methylenebis(cyclohexylisocyanate), methylcyclohexane diisocyanate, bis(isocyanatemethyl)cyclohexane, isophorone diisocyanate, dimer acid diisocyanate, lysine diisocyanate, and the like, as well as modified products of these isocyanates. Specific examples of modified products include biuret modified products, isocyanurate modified products, adduct modified products (e.g., trimethylolpropane adducts), allophanate modified products, and uretdione modified products.

[0192] When an isocyanate is used as the curing component, the resin is desirably a hydroxyl group- and / or amino group-containing resin, and of these, a hydroxyl group-containing resin is preferred.

[0193] In this specification, the curing component selected from carbodiimides and isocyanates is also referred to as "curing component (Y)".

[0194] In the topcoat paint, the amount of the curable component (Y) in the coating film-forming components is preferably 1 to 30 mass %. The curable component (Y) may be used alone or in combination of two or more kinds.

[0195] The topcoat paint preferably contains an ultraviolet absorbing agent. The ultraviolet absorbing agent has the effect of absorbing ultraviolet rays and preventing deterioration caused by ultraviolet rays. By using the ultraviolet absorbing agent, the weather resistance of the coating film can be improved. The ultraviolet absorbing agent may be contained in either the base agent or the curing agent, but it is preferable that the ultraviolet absorbing agent is contained in the base agent.

[0196] Examples of the ultraviolet absorbent include benzophenone-based ultraviolet absorbents, benzoate-based ultraviolet absorbents, benzotriazole-based ultraviolet absorbents, triazine-based ultraviolet absorbents (particularly hydroxyphenyltriazine-based ultraviolet absorbents), and benzylidene camphor-based ultraviolet absorbents. The ultraviolet absorbent may be used alone or in combination of two or more kinds, but it is preferable that the ultraviolet absorbent contains two or more kinds of ultraviolet absorbents with different absorption peaks. The ultraviolet absorbent preferably contains a triazine-based ultraviolet absorbent, and particularly preferably contains a triazine-based ultraviolet absorbent and a benzotriazole-based ultraviolet absorbent.

[0197] Examples of the ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone-2-hydroxy-4-benzyloxybenzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4, 4'-Dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-(dimethylbenzyl)phenyl]benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzo Triazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2,2'-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-(2N-benzotriazol-2-yl)phenol], methyl-3-[3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]phenol, 2-(2-hydroxyphenyl)propionate and polyethylene glycol condensation products, 2-(2-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,6-di-t-butylphenyl-3',5'-di-t-butyl-4'-hydroxybenzoate, hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate, 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butyloxyphenyl)-6-(2,4-bis-butyloxyphenyl)-1,3,5-triazine, hydroxyphenyl triazine, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine, and the like.

[0198] In the topcoat paint, the amount of the ultraviolet absorber in the film-forming components is, for example, 0 to 9 mass %.

[0199] The topcoat paint preferably contains a radical scavenger. The radical scavenger can capture free radicals and improve light stability. In the present invention, the radical scavenger also includes a substance (so-called polymerization inhibitor) that reacts with free radicals and has the function of preventing polymerization reactions from occurring. The use of the radical scavenger can improve the weather resistance of the coating film. The radical scavenger may be contained in either the base agent or the curing agent, but is preferably contained in the base agent.

[0200] Examples of the radical scavenger include hindered amine compounds, hydroquinone compounds, phenol compounds, phenothiazine compounds, nitroso compounds, and N-oxyl compounds, and hindered amine light stabilizers (HALS) are particularly preferred.

[0201] Examples of the radical scavenger include hindered amine compounds such as bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, 1-{2-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)ethyl}-2,2,6,6-tetramethylpiperidine, and 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro{4.5}decane-2,4-dione; phenols; and o-, m-, or p-cresols. phenolic compounds such as 2-t-butyl-4-methylphenol, 6-t-butyl-2,4-dimethylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, 4-t-butyl-2,6-dimethylphenol, hydroquinone, hydroquinone monomethyl ether, methylhydroquinone, 2,5-di-t-butyl Hydroquinone compounds such as 4-methylbenzcatechin, t-butylhydroquinone, 3-methylbenzcatechin, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, benzoquinone, t-butyl-p-benzoquinone, and 2,5-diphenyl-p-benzoquinone; phenothiazine compounds; nitroso-based compounds such as N-nitroso-N-phenylhydroxylamine ammonium and N-nitroso-N-phenylhydroxylamine aluminum salt; and N-oxyl-based compounds such as 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, and 4-methoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl.

[0202] In the topcoat paint, the amount of the radical scavenger in the coating film-forming components is, for example, 0 to 7% by mass. The radical scavengers may be used alone or in combination of two or more.

[0203] The topcoat paint may contain a surfactant. The surfactant is used in the base agent and / or the curing agent as necessary. Surfactants are classified into anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, etc. The amount of the surfactant in the topcoat paint is preferably 10 mass% or less, and more preferably 0.2 to 8 mass%. The surfactant may be used alone or in combination of two or more types.

[0204] The topcoat paint may contain pigments such as color pigments, extender pigments, metallic pigments, glitter pigments, and scale-like pigments. The pigments may be contained in either the base agent or the curing agent, but are preferably contained in the base agent. Examples of color pigments include inorganic pigments such as titanium dioxide, iron oxide, and carbon black, and organic pigments such as phthalocyanine pigments and azo pigments. Examples of extender pigments include silica, resin beads, talc, mica, calcium carbonate, barium sulfate, and clay. Other pigments include aluminum powder pigments, nickel powder pigments, gold powder, silver powder, bronze powder, copper powder, stainless steel powder pigments, mica pigments, graphite pigments, glass flake pigments, metal-coated glass powder, metal-coated mica powder, metal-coated plastic powder, and scale-like iron oxide pigments.

[0205] In the topcoat paint, the amount of pigment in the coating film forming components is preferably 60% by mass or less, and more preferably 0 to 30% by mass. The pigments may be used alone or in combination of two or more kinds.

[0206] The topcoat paint may contain other components, such as film-forming aids, antifreezing agents, wetting agents, dispersants, defoamers, viscosity adjusters, thickeners, anti-settling agents, anti-skinning agents, anti-sagging agents, color separation inhibitors, matting agents, adhesion imparting agents, leveling agents, drying agents, catalysts, plasticizers, anti-fungal agents, antibacterial agents, antiviral agents, preservatives, insecticides, antistatic agents, and conductivity imparting agents, as appropriate depending on the purpose.

[0207] The base agent and the curing agent can be prepared by mixing various components appropriately selected as necessary. The topcoat paint can be prepared by mixing the base agent, the curing agent, and additives as necessary at the time of painting.

[0208] The topcoat paint is preferably a clear paint.

[0209] The topcoat paint preferably has a viscosity of 1 to 1000 (Pa·s, 23° C.) at a shear rate of 0.1 (1 / s), and a viscosity of 0.05 to 10 (Pa·s, 23° C.) at a shear rate of 1000 (1 / s).

[0210] The means for applying the topcoat paint is not particularly limited, and known applying means such as brush application, roller application, trowel application, spatula application, flow coater application, spray application (e.g., air spray application, airless spray application), etc. can be used.

[0211] The means for drying the topcoat paint is not particularly limited, and may be either natural drying at ambient temperature or forced drying using a dryer or the like.

[0212] The elastic modulus of the topcoat at 23°C is 200N / mm 2 ~450N / mm 2 It is preferable that the strength is 250N / mm 2 ~400N / mm 2 It is more preferable that the elastic modulus of the topcoat coating film is within the above-specified range, and thus the frost resistance is improved, the coating film is less likely to crack, and the alkali resistance is improved, and since the elastic modulus is appropriate, contaminants are less likely to adhere, and the stain resistance is improved. The elastic modulus can be adjusted by the type of monomer constituting the resin and the crosslink density.

[0213] By setting the elastic modulus of the topcoat coating film within the above-specified range, cracking of the coating film is unlikely to occur in the frost resistance test. In particular, since the present invention aims to obtain a paint that can also be used for repainting a photocatalytic coating film, the undercoat coating film has a characteristic of having a high silicon content, and the topcoat coating film is required to ensure adhesion to the undercoat coating film and to be unlikely to crack. Furthermore, when the substrate or old coating film contains a large amount of inorganic components, it is preferable that the topcoat coating film also has excellent alkali resistance. By setting the elastic modulus of the topcoat coating film within the above-specified range, adhesion is ensured even when a coating film is formed on such an undercoat coating film with a high silicon content, and the coating film is unlikely to crack, leading to improved alkali resistance and frost resistance as a coated body. In addition, since the elastic modulus is moderate, contaminants are unlikely to adhere, and the contamination resistance is improved. The elastic modulus can be adjusted by the type of monomer constituting the resin and the crosslink density.

[0214] The elastic modulus of the topcoat film can be calculated from the slope (proportionality constant) within the range in which stress and strain are proportional using a tensile test. In this specification, the elastic modulus of the topcoat film is determined by applying a coating material to a polypropylene plate so that the dry film thickness is 30 to 60 μm, drying at 23°C for 6 hours and then at 50°C for 3 days, and then cutting out a flat test piece with a width of 10 mm and a length of 50 mm. A tensile test is performed in an environment of 23°C and 50% humidity under the conditions of a chuck distance of 30 mm, a load of 1.0 kN, and a speed of 5 mm / min. From the obtained stress-strain curve, the slope at a load of 1.0 to 1.5 kN is defined as the elastic modulus (N / mm 2 )

[0215] The elongation percentage of the topcoat coating film at 23° C. is preferably greater than the elongation percentage of the undercoat coating film at 23° C., and is preferably 50% or more, and more preferably 80% or more. There is no particular upper limit to the elongation percentage of the topcoat coating film, but the elongation percentage at 23° C. is, for example, 250% or less.

[0216] The visible light transmittance of the topcoat coating film is preferably 20% or more, more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, and most preferably 100%.

[0217] The UV transmittance of the topcoat coating is preferably 20% or less, more preferably 10% or less, and most preferably 0%.

[0218] The silicon content in the resin constituting the topcoat coating film is preferably the same as or less than the silicon content in the resin constituting the undercoat coating film, and is preferably 0 to 0.4 mass %.

[0219] The topcoat coating film contains preferably 40 to 98 mass %, more preferably 50 to 95 mass %, of a resin having a glass transition temperature of 20 to 90° C. When the resin having a glass transition temperature of 20 to 90° C. is contained in the above-specified amount, a coating film having excellent stain resistance can be obtained. The resin having a glass transition temperature of 20 to 90° C. may be a water-dispersible resin containing an acrylic component or may be another resin, but is preferably a water-dispersible resin containing an acrylic component.

[0220] In this specification, the glass transition temperature (Tg) of a resin is calculated using the following FOX formula. 1 / Tg=W1 / Tg1+W2 / Tg2+···+Wi / Tgi+···+Wn / Tgn In the FOX equation, Tg is the glass transition temperature (K) of a polymer consisting of n types of monomers, Tg(1, 2, i, n) is the glass transition temperature (K) of the homopolymer of each monomer, W(1, 2, i, n) is the mass fraction of each monomer, and W1+W2+···+Wi+···+Wn=1.

[0221] The glass transition temperature of a homopolymer is common technical knowledge. When a monomer with an unknown glass transition temperature is used, the glass transition temperature of the monomer can be determined by differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermomechanical analysis (TMA), etc.

[0222] The topcoat coating film preferably contains 10 to 100 mass % of a resin having a minimum film-forming temperature of 20 to 60° C. The resin having a minimum film-forming temperature of 20 to 60° C. may be a water-dispersible resin containing an acrylic component or may be another resin, but is preferably a water-dispersible resin containing an acrylic component.

[0223] In this specification, the minimum film-forming temperature of a resin means the minimum film-forming temperature (MFT) of the resin emulsion, and is measured in accordance with JIS K6828-2:2003.

[0224] The dry film thickness of the topcoat coating is preferably 10 to 50 μm.

[0225] The topcoat coating film preferably has a dry film thickness of 10 to 50 μm. The topcoat coating film preferably has a visible light transmittance of 20% or more, more preferably 60% or more, even more preferably 70% or more, particularly preferably 80% or more, and most preferably 100%. The topcoat coating film preferably has an ultraviolet light transmittance of 20% or less, more preferably 10% or less, and most preferably 0%.

[0226] The repair method of the present invention may include a step of applying an intermediate coating on the undercoat coating to form an intermediate coating. In this case, the topcoat coating is applied on the intermediate coating to form a topcoat coating. The intermediate coating can provide a new design to the building exterior material. The intermediate coating may be the coating composition of the present invention, or another coating composition. The intermediate coating paint is preferably an aqueous coating paint using water as the main solvent, and can be prepared by appropriately blending resins, crosslinking agents, pigments, surface conditioners, wetting agents, dispersants, defoamers, viscosity adjusters, thickeners, anti-settling agents, anti-skinning agents, anti-sagging agents, color separation inhibitors, matting agents, adhesion imparting agents, leveling agents, drying agents, plasticizers, film-forming assistants, antifungal agents, antibacterial agents, antiviral agents, preservatives, insecticides, charge control agents, stress relaxation agents, penetrating agents, light-guiding materials, glittering materials, magnetic materials, phosphors, ultraviolet absorbers, radical scavengers, antistatic agents, and conductivity imparting agents according to the purpose. The intermediate coating film preferably has a dry film thickness of 10 to 50 μm.

[0227] A preferred embodiment of the repair method of the present invention is a method for repairing an architectural exterior material, which comprises the steps of: removing contaminants on the old coating film without peeling or removing the old coating film on the surface of the architectural exterior material, applying the paint composition of the present invention obtained by mixing a base agent and a curing agent onto the old coating film to form an undercoat coating film; and applying a topcoat paint onto the undercoat coating film to form a topcoat coating film.

[0228] Water-dispersible resin (X): Water-dispersible resin containing acrylic components The water-dispersible resin (X) that can be used in the top coat paint is described below. Unless otherwise specified, the water-dispersible resin (X) is described as the water-dispersible resin (X) that can be used in the top coat paint.

[0229] The water-dispersible resin (X) is a water-dispersible resin containing an acrylic component, and includes polymers obtained by polymerizing one or more types of acrylic components, polymers obtained by polymerizing an acrylic component with a non-acrylic component such as styrene, etc. Examples of the water-dispersible resin (X) include acrylic resins, as well as various modified resins such as acrylic silicone resins, acrylic styrene resins, fluorine-modified acrylic resins, fatty acid-modified acrylic resins, urethane-modified acrylic resins, and epoxy-modified acrylic resins.

[0230] Examples of the acrylic component include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, phenyl (meth)acrylate, and the like. Examples of the monomer include (meth)acrylate monomers such as butyl (meth)acrylate, benzyl (meth)acrylate, methoxyethyl (meth)acrylate, ethoxyethyl (meth)acrylate, methoxypropyl (meth)acrylate, and ethoxypropyl (meth)acrylate; and functional group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl acrylate, 2-aminoethyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, 3-aminopropyl (meth)acrylate, 2-butylaminoethyl (meth)acrylate, glycidyl (meth)acrylate, and allyl glycidyl ether. Further, the acrylic component also includes acrylic acid, methacrylic acid; amide monomers such as acrylic acid amide and methacrylic acid amide; and alkoxysilyl group-containing monomers such as γ-(meth)acryloxypropyltrimethoxysilane, γ-(meth)acryloxypropyltriethoxysilane, β-(meth)acryloxyethyltrimethoxysilane, β-(meth)acryloxyethyltriethoxysilane, γ-(meth)acryloxypropylmethyldimethoxysilane, γ-(meth)acryloxypropylmethyldiethoxysilane, γ-(meth)acryloxypropylmethyldipropoxysilane, γ-(meth)acryloxybutylphenyldimethoxysilane, γ-(meth)acryloxypropyldimethylmethoxysilane, and γ-(meth)acryloxypropyldiethylmethoxysilane.

[0231] The amount of the acrylic component contained as a structural unit in the water-dispersible resin (X) is, for example, 40 to 100 mass %. The acrylic components may be used alone or in combination of two or more.

[0232] In this specification, the term (meth)acrylate means methacrylate or acrylate. For example, 2-ethylhexyl (meth)acrylate is 2-ethylhexyl acrylate or 2-ethylhexyl methacrylate. In addition, a prefix indicating a plurality of (meth)acrylates may be added to (meth)acrylates, such as di(meth)acrylate, tri(meth)acrylate, etc., in which case each (meth)acrylate may be the same or different.

[0233] Examples of non-acrylic components include carboxyl group-containing monomers such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, and vinyl versatic acid; aromatic monomers such as styrene, methylstyrene, chlorostyrene, methoxystyrene, and vinyltoluene; olefin monomers such as ethylene and propylene; vinyl monomers such as vinyl acetate and vinyl chloride; amide monomers such as maleic acid amide; alkoxysilyl group-containing monomers such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane; dialkyl fumarate, allyl alcohol, vinylpyridine, and butadiene.

[0234] The water-dispersible resin (X) preferably contains a monomer having an alkyl group with 4 or more carbon atoms as a structural unit. The monomer having an alkyl group with 4 or more carbon atoms has high water resistance because it has a highly hydrophobic alkyl group, and furthermore, it has flexibility, so it can improve the frost resistance of the coating film. The greater the carbon number of the alkyl group, the greater the effect of improving water resistance and frost resistance. Therefore, the number of carbon atoms of the alkyl group is not particularly limited as long as it is 4 or more, but the upper limit of the number of carbon atoms of the alkyl group can be, for example, 12 or less from the viewpoint of copolymerization with other monomers and solubility in water. In addition, the alkyl group has a higher effect of improving water resistance and frost resistance when it is a linear or branched alkyl group than when it is a cyclic group (when it is a cyclic alkyl group such as a cyclohexyl group).

[0235] The monomer having an alkyl group having 4 or more carbon atoms may be either an acrylic component or a non-acrylic component, but is preferably an acrylic component having an alkyl group having 4 or more carbon atoms, and more preferably a (meth)acrylate having an alkyl group having 4 or more carbon atoms. Examples of monomers having an alkyl group having 4 or more carbon atoms include isobutyl (meth)acrylate, 1-ethylpropyl (meth)acrylate, t-pentyl (meth)acrylate, neopentyl (meth)acrylate, n-butyl (meth)acrylate, 2-methylbutyl (meth)acrylate, isopentyl (meth)acrylate, 3-methylbutyl (meth)acrylate, 2-ethylbutyl (meth)acrylate, n-pentyl (meth)acrylate, acrylate, 2-methylpentyl (meth)acrylate, 4-methylpentyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-heptyl (meth)acrylate, isooctyl (meth)acrylate, n-octyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, and n-lauryl (meth)acrylate.

[0236] The amount of monomers having an alkyl group with 4 or more carbon atoms contained as structural units in the water-dispersible resin (X) is preferably 50 to 75% by mass, more preferably 55 to 70% by mass. However, the monomers having an alkyl group with 4 or more carbon atoms here are monomers having an alkyl group with 4 or more carbon atoms excluding monomers having a cyclic structure. If the amount of monomers having an alkyl group with 4 or more carbon atoms contained as structural units in the water-dispersible resin (X) (excluding monomers having a cyclic structure) is 50% by mass or more, the water resistance and frost resistance of the coating film can be improved. In addition, if the amount of monomers having an alkyl group with 4 or more carbon atoms contained as structural units in the water-dispersible resin (X) (excluding monomers having a cyclic structure) exceeds 75% by mass, when cured with a curing component such as carbodiimide, isocyanate, or silane compound, the balance between the coating film hardness and the substrate adhesion may be poor, and the frost resistance of the coating film may be reduced.

[0237] The water-dispersible resin (X) preferably contains, as a structural unit, a monomer having an SP value of less than 9.5. Monomers having an SP value of less than 9.5 are highly hydrophobic, and therefore can improve the water resistance of the coating film and further improve the frost resistance of the coating film. The SP value of the monomer is preferably 8.50 to 9.40.

[0238] The monomer having an SP value of less than 9.5 may be either an acrylic component or a non-acrylic component, but is preferably an acrylic component. Examples of the monomer having an SP value of less than 9.5 include n-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, stearyl (meth)acrylate, lauryl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, and isobornyl (meth)acrylate.

[0239] The amount of the monomer having an SP value of less than 9.5 contained as a structural unit in the water-dispersible resin (X) is preferably 10 to 90 mass %, more preferably 20 to 85 mass %. The monomer having an SP value of less than 9.5 may be used alone or in combination of two or more kinds.

[0240] The SP value (solubility parameter) is a guideline for determining compatibility, and there are various calculation and measurement methods. In this specification, the SP value of a monomer means a value calculated in accordance with the method described in the literature [KL Hoy, J. Paint Technology, 42,

[0541] , 76 (1970)] using the molecular attractive constant obtained using the SP value by the vapor pressure method proposed by Hoy. Specifically, the SP value is expressed as δ=(dΣG) / M, where d is the density of the polymer, M is the molecular weight of the basic structural unit of the polymer, and ΣG is the sum of the molecular attractive constants G corresponding to the atoms (groups) present in the basic structural unit.

[0241] The water-dispersible resin (X) preferably contains a polymerizable ultraviolet absorber as a structural unit. By polymerizing the ultraviolet absorber together with the raw material monomer of the water-dispersible resin, it is possible to prevent the ultraviolet absorber from flowing out of the coating film and maintain weather resistance for a long period of time. Examples of the polymerizable ultraviolet absorber include ultraviolet absorbing monomers such as benzotriazole-based ultraviolet absorbing monomers and benzophenone-based ultraviolet absorbing monomers.

[0242] Examples of benzotriazole-based ultraviolet absorbing monomers include 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-5-tert-butyl-2H-benzotriazole, and 2-[2'-hydroxy-5'-(meth)acryloylaminomethyl-5'-tert-octylphenyl]-2H-benzotriazole. Azole, 2-[2'-hydroxy-5'-(meth)acryloyloxypropylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyhexylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-(meth)acryloyloxyethylphenyl]-5-chloro-2H-benzotriazole, 2-[2'-hydroxy -5'-tert-butyl-3'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-chloro-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-cyano-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-tert-butyl-2H-benzotriazole, 2-[2'-hydroxy-5'-(β-(meth)acryloyloxyethylphenyl]- [2-[2'-hydroxy-5'-(meth)acryloyloxyethoxy]-3'-tert-butylphenyl]-4-tert-butyl-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-methoxy-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-nitro-2H-benzotriazole, 3-(meth)acryloyl-2-hydroxypropyl-3-[3-(2-benzotriazolyl)-4-hydroxy-5-tert-butyl]phenylpropionate, and the like.

[0243] Examples of benzophenone-based ultraviolet absorbing monomers include 2-hydroxy-4-(meth)acryloyloxybenzophenone, 2-hydroxy-4-[2-hydroxy-3-(meth)acryloyloxy]propoxybenzophenone, 2-hydroxy-4-[2-(meth)acryloyloxy]ethoxybenzophenone, 2-hydroxy-4-[3-(meth)acryloyloxy-2-hydroxypropoxy]benzophenone, 2-hydroxy-3-tert-butyl-4-[2-(meth)acryloyloxy]butoxybenzophenone, and 2,2'-dihydroxy-4-[3-(meth)acryloyloxy-2-hydroxypropoxy]benzophenone.

[0244] The amount of the polymerizable ultraviolet absorber contained as a structural unit in the water-dispersible resin (X) is, for example, 0 to 9.0 mass %. The polymerizable ultraviolet absorbers may be used alone or in combination of two or more.

[0245] The water-dispersible resin (X) preferably contains a polymerizable radical scavenger as a structural unit. By polymerizing the radical scavenger together with the raw material monomer of the water-dispersible resin, it is possible to prevent the radical scavenger from flowing out of the coating film and maintain weather resistance for a long period of time. Examples of the polymerizable radical scavenger include polymerizable light-stable monomers. The polymerizable light-stable monomer is a compound having a polymerizable group and a functional group having a light stabilizing effect. Examples of the polymerizable group include polymerizable unsaturated groups such as an alkenyl group (vinyl group, allyl group, etc.) and an alkenylcarbonyl group (e.g., (meth)acryloyl group, crotonoyl group, etc.).

[0246] Examples of the polymerizable light-stable monomer include, in addition to the hindered amine-based polymerizable light-stable monomers described below, a reaction product of decanedioic acid bis(2,2,6,6-tetramethyl-1-(octyloxy)-4-piperidinyl) ester, 1,1-dimethylethyl hydroperoxide, and octane, bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]butyl malonate, and a mixture of bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate and methyl 1,2,2,6,6-pentamethyl-4-piperidylsebacate.

[0247] Examples of the hindered amine polymerizable light-stable monomer include polymerizable compounds having a piperazine skeleton (particularly, a 2,2,6,6-tetramethylpiperidine skeleton) (compounds having a piperazine skeleton and a polymerizable group).

[0248] Representative hindered amine-based polymerizable light-stable monomers include compounds represented by the following structural formula (1). [ka] In structural formula (1), R 1 and R 2 is a hydrogen atom or an alkyl group, and R 3 , R 4 , R 5 and R 6 is an alkyl group, X is an oxygen atom (-O-) or an imino group (-NH-), and Y and Z are hydrogen atoms or substituents.

[0249] R in structural formula (1) 1 ~R 6 In the above, examples of the alkyl group include a C alkyl group such as a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, a s-butyl group, and a t-butyl group. 1-20 Alkyl groups, preferably C 1-10 Alkyl groups, more preferably C 1-4An alkyl group is preferable, and a methyl group is particularly preferable. Representative R 1 and R 2 is a hydrogen atom or a methyl group, and in particular R 1 is a hydrogen atom, R 2 is preferably a hydrogen atom or a methyl group. 3 ~R 6 is a methyl group.

[0250] The substituents in Y and Z in the structural formula (1) include hydrocarbon groups [e.g., alkyl groups {e.g., the above-mentioned alkyl groups such as methyl groups (e.g., C 1-20 Alkyl groups, preferably C 1-4 alkyl group)}], alkoxy group (e.g., methoxy group, ethoxy group, etc. 1-20 Alkoxy groups, preferably C 1-10 Alkoxy groups, more preferably C 1-4 alkoxy groups, particularly preferably methoxy groups), acyl groups (e.g., C 1-10 acyl group), halogen atoms (for example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, hydroxyl group, polymerizable groups (for example, (meth)acryloyl group, crotonoyl group), etc.

[0251] In the structural formula (1), representative Y is a hydrogen atom, an alkyl group (e.g., a C group such as a methyl group), 1-4 alkyl group), alkoxy group (e.g., methoxy group, etc. 1-4 Alkoxy groups), acyl groups (e.g., acetyl groups, etc. 1-4 Examples of Z include an acyl group, a (meth)acryloyl group, a crotonoyl group, etc., and in particular, a hydrogen atom or a methyl group is preferable. Representative examples of Z include a hydrogen atom or a cyano group, and in particular, a hydrogen atom is preferable.

[0252] Examples of the hindered amine-based polymerizable light-stable monomer include 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine having a substituent {e.g., 4-(meth)acryloyloxy-2,2,6,6-tetramethyl-1-alkylpiperidine [e.g., 4-(meth)acryloyloxy-1-C such as 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 1-4 alkyl-2,2,6,6-tetramethylpiperidine], 4-(meth)acryloyloxy-2,2,6,6-tetramethyl-1-alkoxypiperidine [e.g., 4-(meth)acryloyloxy-1-C alkyl-2,2,6,6-tetramethylpiperidine, etc. 1-4 N-substituted (meth)acryloyloxy-2,2,6,6-tetramethylpiperidines such as alkoxy-2,2,6,6-tetramethylpiperidine, 4-substituted-4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidines such as 4-cyano-4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, etc., 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidines such as 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, etc. 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidines having a substituent {e.g., 4-(meth)acryloylamino-2,2,6,6-tetramethyl-1-alkylpiperidines [e.g., 4-(meth)acryloylamino-2,2,6,6-tetramethyl-1-alkylpiperidines such as 4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine, etc. 1-4N-substituted (meth)acryloylamino-2,2,6,6-tetramethylpiperidines such as alkylpiperidines, 4-substituted-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidines such as 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, etc.} 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidines; 4-crotonoylamino-2,2,6,6-tetramethylpiperidine; 1-( Examples of the 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine include 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine and 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine; and 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine and other 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine.

[0253] The amount of the polymerizable radical scavenger contained as a structural unit in the water-dispersible resin (X) is, for example, 0 to 7 mass %. The polymerizable radical scavenger may be used alone or in combination of two or more kinds.

[0254] In particular, the water-dispersible resin (X) used in the topcoat paint preferably contains a polymerizable ultraviolet absorber and / or a polymerizable radical scavenger as a structural unit, from the viewpoint of improving weather resistance.

[0255] The water-dispersible resin (X) preferably contains a reactive emulsifier as a structural unit, which can suppress the emulsifier from leaching out from the coating film and improve the water resistance and frost resistance of the coating film.

[0256] Examples of the reactive emulsifier include anionic reactive emulsifiers and nonionic reactive emulsifiers. The water-dispersible resin (X) preferably contains both anionic reactive emulsifiers and nonionic reactive emulsifiers as structural units.

[0257] From the viewpoint of emulsion stability, the reactive emulsifier preferably has a polyalkylene glycol chain. Examples of the polyalkylene glycol chain include a polyethylene glycol chain and a polypropylene glycol chain. From the viewpoint of water resistance and emulsion stability, the reactive emulsifier preferably has a molecular weight within the range of 200 to 3,500.

[0258] Examples of reactive emulsifiers include emulsifiers having polymerizable unsaturated bonds such as vinyl groups in the molecule. Such reactive emulsifiers not only have an emulsifying function, but are also polymerizable monomers having polymerizable unsaturated bonds such as vinyl groups and hydrophilic groups in the molecule. While ordinary emulsifiers are only adsorbed to the surface of the resulting particles, reactive emulsifiers may be incorporated into the polymer as a component of the polymer during the polymerization process of the polymer, but not all of them, and therefore have the characteristic that the emulsifier is not or is difficult to be liberated from the polymer after the coating film is formed due to external factors such as water vapor. In addition, the formation of a protective layer in which the reactive emulsifier containing a polyalkylene glycol chain is bonded to the surface of the water-dispersible resin leads to improved frost resistance.

[0259] Examples of the anionic reactive emulsifier include alkyl ether type (commercially available products include Aqualon KH-05 and KH-10 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Adeka Reasoap SR-10, SR-1025, SR-20, and R-3025 manufactured by ADEKA Corporation, and Latemul PD-104 manufactured by Kao Corporation), sulfosuccinate ester type (commercially available products include Latemul S-120, S-120A, S-180P, and S-180A manufactured by Kao Corporation, and Eleminol JS-20 manufactured by Sanyo Chemical Industries, Ltd.), alkyl phenyl ether type, and alkyl phenyl ester type (commercially available products include Aqualon KH-05 and KH-10 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), and alkyl phenyl ether type. Examples of commercially available products include Aqualon HS-10, HS-1025, AR-10, AR-1025, AR-20, AR-2020, BC-10, BC-1025, BC-20, and BC-2020 manufactured by Nippon Nyukazai Co., Ltd., and Adeka Reasop SE-10N and SE-1025A manufactured by ADEKA Corporation), (meth)acrylate sulfate ester type (commercially available products include, for example, Antox MS-60, SAD, and MS-2N manufactured by Nippon Nyukazai Co., Ltd., and Eleminol RS-3000 manufactured by Sanyo Chemical Industries, Ltd.), and phosphate ester type (commercially available products include, for example, H-3330PL manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., and Adeka Reasop PP-70 manufactured by ADEKA Corporation).

[0260] Examples of the nonionic reactive emulsifier include alkyl ether type (commercially available products include Aqualon KN-10, KN-20, KN-30, and KN-5065 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Adeka Reasoap ER-10, ER-20, ER-30, and ER-40 manufactured by ADEKA Corporation, and Latemul PD-420, PD-430, and PD-450 manufactured by Kao Corporation), alkyl phenyl ether type, and alkyl phenyl ester type (commercially available products include Aqualon KN-10, KN-20, KN-30, and KN-5065 manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd., Adeka Reasoap ER-10, ER-20, ER-30, and ER-40 manufactured by ADEKA Corporation, and Latemul PD-420, PD-430, and PD-450 manufactured by Kao Corporation). and Adeka Reasoap NE-10, NE-20, NE-30, RN-50, AN-10, AN-20, AN-30, AN-5065 manufactured by ADEKA CORPORATION, and Adeka Reasoap NE-10, NE-20, NE-30, etc.), (meth)acrylate ester type (commercially available products include, for example, MA-50A, MA-100A, MPG-130MA manufactured by Nippon Nyukazai Co., Ltd., and Blenmar PE-90, PP-1000, 50PEP-300, AE-200, AP-400, etc. manufactured by NOF Corporation).

[0261] The amount of the reactive emulsifier contained as a structural unit in the water-dispersible resin (X) is preferably 0.1 to 10% by mass. The reactive emulsifier may be used alone or in combination of two or more kinds.

[0262] In the topcoat paint, the water-dispersible resin (X) is preferably a water-dispersible resin whose weight-average molecular weight exceeds 300,000 or whose weight-average molecular weight cannot be measured. In this specification, the term "water-dispersible resin whose weight-average molecular weight cannot be measured" refers to a water-dispersible resin whose weight-average molecular weight cannot be measured by gel permeation chromatography (GPC) due to the presence of a crosslinked structure. In the present invention, the "water-dispersible resin whose weight-average molecular weight cannot be measured" is treated as a high molecular weight resin, similar to the "water-dispersible resin whose weight-average molecular weight exceeds 300,000".

[0263] In this specification, the weight average molecular weight is a value measured by gel permeation chromatography (GPC), using polystyrene as the standard substance and tetrahydrofuran as the mobile phase.

[0264] The water-dispersible resin (X) is preferably dispersed in the paint in the form of an emulsion. For this reason, when preparing a topcoat paint, it is preferable to use an emulsion of the water-dispersible resin (X). The emulsion of the water-dispersible resin (X) means an emulsion in which the water-dispersible resin (X) is stably dispersed in water, and may contain additives such as an emulsifier as necessary. Note that a paint in which the resin is dispersed in the form of an emulsion in this way is also called an emulsion paint.

[0265] The water-dispersible resin (X) emulsion can be prepared, for example, by carrying out emulsion polymerization in water using water as a medium. More preferably, a water-dispersible resin (X) emulsion having a uniform structure obtained by emulsion polymerization, a water-dispersible resin (X) emulsion having a heterogeneous phase structure obtained by a multi-stage emulsion polymerization method, and the like can be mentioned, and both of these may be used together. Alternatively, the water-dispersible resin (X) emulsion can be prepared as follows. For example, the water-dispersible resin (X) emulsion can be prepared by emulsifying the water-dispersible resin (X) in water while applying a forced shear force by using a high-speed stirrer or the like. The water-dispersible resin (X) emulsion can also be prepared by carrying out phase inversion into water for the water-dispersible resin (X) polymerized in an organic solvent medium, and the organic solvent contained in the water-dispersible resin (X) emulsion can be removed by distillation or the like as necessary.

[0266] Furthermore, in order to improve the functionality of the resulting coating film, it is possible to introduce a crosslinked structure into the water-dispersible resin (X). Generally, crosslinked structures are roughly divided into two types: "interparticle crosslinked structures" and "interparticle crosslinked structures."

[0267] By introducing this "intraparticle crosslinked structure" or "interparticle crosslinked structure" into the water-dispersible resin (X), it is possible to improve the coating film performance such as toughness, water resistance, and frost resistance when formed into a coating film.

[0268] In order to obtain the intraparticle crosslinked and interparticle crosslinked structures, for example, the following method may be used.

[0269] Intra-particle crosslinking: A monomer having two or more polymerizable unsaturated double bonds in the molecule is used. Examples of such methods include a method using divinylbenzene, ethylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, allyl (meth)acrylate, or the like; a method using monomers having functional groups which react with each other at the temperature during emulsion polymerization reaction, such as a method using monomers having a combination of functional groups such as a carboxyl group and a glycidyl group, or a hydroxyl group and an isocyanate group; and a method using hydrolyzable silyl group-containing monomers which undergo hydrolysis and condensation reaction, such as (meth)acryloxypropyltrimethoxysilane, (meth)acryloxypropylmethyldimethoxysilane, and the like.

[0270] Inter-particle cross-linking: The most typical method is to copolymerize a monomer having a carbonyl group, and then mix a compound having two or more hydrazide groups in the molecule. Examples of the carbonyl group-containing monomer include acrolein, diacetone (meth)acrylamide, formyl styrol, (meth)acryloxyalkyl propanal, diacetone (meth)acrylate, acetonyl (meth)acrylate, acetoacetoxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate-acetyl acetate, butanediol-1,4-acrylate-acetyl acrylate, vinyl ethyl ketone, vinyl isobutyl ketone, etc. In particular, acrolein, diacetone acrylamide, and vinyl ethyl ketone are preferred. On the other hand, examples of compounds having two or more hydrazide groups in the molecule that are paired with the carbonyl group include carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, dodecanoic acid dihydrazide, isophthalic acid dihydrazide, citric acid trihydrazide, 1,2,4-benzene trihydrazide, and thiocarbodihydrazide, etc. Among these, carbohydrazide, adipic acid dihydrazide, and succinic acid dihydrazide are preferred in terms of the balance of dispersibility in emulsions and water resistance.

[0271] For emulsion polymerization, surfactants generally used in emulsion polymerization can be used as emulsifiers. For example, anionic surfactants such as fatty acid salts such as sodium lauryl sulfate, higher alcohol sulfate salts, alkylbenzene sulfonates such as sodium dodecylbenzene sulfonate, polyoxyethylene alkyl ether sulfate salts, ammonium polyoxynonyl phenyl ether sulfonate, ammonium polyoxyethylene styrenated phenyl ether sulfate salts, polyoxyethylene-polyoxypropylene glycol ether sulfate salts, and so-called reactive emulsifiers having a sulfonic acid group or a sulfate ester group and a polymerizable carbon-carbon unsaturated double bond in the molecule; nonionic surfactants such as polyoxyethylene alkyl ethers, polyoxyethylene nonyl phenyl ethers, sorbitan fatty acid esters, polyoxyethylene fatty acid esters, polyoxyethylene-polyoxypropylene block copolymers, or reactive nonionic surfactants having a polymerizable carbon-carbon unsaturated double bond in the molecule with the above-mentioned skeleton; cationic surfactants such as alkylamine salts and quaternary ammonium salts. Among these, anionic surfactants that are ammonium salts are preferred because of their high water resistance.

[0272] In preparing the water-dispersible resin (X), a reactive emulsifier and a non-reactive emulsifier may be used in combination.

[0273] The water-dispersible resin (X) emulsion preferably has a pH of 7 to 10. For example, the pH of the water-dispersible resin (X) emulsion can be adjusted to within the above-specified range using a neutralizing agent. If the pH of the water-dispersible resin (X) emulsion is less than 7, various stabilities such as storage stability and mechanical stability of the paint may decrease, while if it exceeds 10, drying may become slow. The neutralizing agent that can be used here is preferably a neutralizing agent selected from the group consisting of ammonia, alkaline inorganic compounds, and alkaline organic compounds having a boiling point of more than 260°C.

[0274] In the water-dispersible resin (X) emulsion, the acrylic component or non-acrylic component used as the raw material of the water-dispersible resin (X) may remain unpolymerized. In addition, the raw material of the water-dispersible resin (X) emulsion may contain ammonia or VOC compounds. From the viewpoint of suppressing the generation of odor, it is preferable to remove such remaining unreacted monomers, ammonia, and VOC compounds. For this reason, it is preferable to remove them under reduced pressure during or after the preparation of the water-dispersible resin (X) emulsion.

[0275] The water-dispersible resin (X) preferably has an average particle size of 50 to 200 nm, more preferably 60 to 150 nm, and particularly preferably 70 to 120 nm. EXAMPLES

[0276] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples. In the examples, "parts" and "%" are based on mass unless otherwise specified.

[0277] Resins 1 to 5 used in the preparation of the main component described below are synthetic resin emulsions, the details of which are as follows. Resin 1: silanol group and urethane group-containing acrylic resin dispersion (silicon content in resin: 11.7%, average particle size of resin: 50 nm, non-volatile content in dispersion: 40%) Resin 2: Silanol group-containing acrylic resin dispersion (silicon content in resin: 11.7%, average particle size of resin: 50 nm, non-volatile content in dispersion: 40%) Resin 3: Silanol group-containing acrylic resin dispersion (silicon content in resin: 0.4%, average particle size: 100 nm, non-volatile content: 40%) Resin 4: Acrylic resin dispersion (silicon content in resin: 0%, average particle size of resin: 100 nm, non-volatile content in dispersion: 40%) Resin 5: Aliphatic polyurethane dispersion (silicon content in resin: 0%, average particle size of resin: 40 nm, non-volatile content in dispersion: 30%) The synthetic resin emulsions of Resin 4 and Resin 5 do not contain a resin having a silanol group, which is the component (A-1).

[0278] <Preparation of base agent> Each main component was obtained by mixing and stirring the ingredients thoroughly according to the formulation shown in Table 2. The additives shown in Table 2 are as follows. The "film-forming aid" was Dowanol DPnB (Dow Chemical Japan, Ltd.). "UVA / HALS" is Tinuvin 1130 / Tinuvin 292 (BASF Japan Ltd.). The "preservative" is PROXEL DAC (Lonza Japan Co., Ltd.). The "defoamer" is Defoamer 1316 (San Nopco Ltd.). The "viscosity adjuster" is Adekanol UH-420 (ADEKA Corporation).

[0279] <Preparation of hardener> According to the formulation shown in Table 1, the materials were blended, thoroughly mixed and stirred to obtain curing agents 1 to 3. The components shown in Table 1 are as follows. "Silicate 40" is a partial condensate of tetraethoxysilane (residual silica ratio: 40%) (Tama Chemicals Co., Ltd.). "KR500" is silicone oligomer KR-500 (Shin-Etsu Chemical Co., Ltd.). The "surfactant" is EnviroGem AD01 (Evonik Japan Co., Ltd.). The "water-based crosslinking agent" is Carbodilite V-04B (Nisshinbo Chemical Inc.). The "film-forming aid" was Dowanol DPnB (Dow Chemical Japan, Ltd.). Among the silane compounds shown in Table 1, Silicate 40 corresponds to component (B-1).

[0280] [Table 1]

[0281] In Table 1, "Film-forming components (mass %)" indicates the amount (mass %) of the film-forming components contained in the curing agent, and "Silicon content in the film-forming components of the curing agent (mass %)" indicates the silicon content (mass %) of the film-forming components contained in the curing agent.

[0282] <Paint preparation> The above base agent and curing agent were mixed and stirred in the mixing ratio (mass ratio) shown in Table 2 to obtain each paint.

[0283] [Table 2]

[0284] <Adjustment of top coat paint> A base agent was prepared by mixing 85 parts of resin 6 [acrylic silicone resin dispersion (silicon content in resin 0.09%, average particle size of resin 110 nm, acid value 16.8 mg KOH / g, non-volatile content in dispersion 45%)], 4.9 parts of ion-exchanged water, 8.0 parts of film-forming aid, 1.0 parts of UVA / HALS, 0.1 parts of preservative, 0.5 parts of defoamer, and 0.5 parts of viscosity adjuster, and 100 parts of Carbodilite E-05 (Nisshinbo Chemical Inc., non-volatile content 40%) was used as a hardener. The base agent and hardener were mixed in a 95 / 5 ratio (by weight) immediately after use to obtain topcoat paint 1. The film-forming aid, UVA / HALS, preservative, defoamer and viscosity adjuster used in the preparation of topcoat paint 1 are as described above in <Preparation of base paint>. In addition, resin 6 in topcoat paint 1 was changed to resin 7 (acrylic resin dispersion: silicon content in resin 0%, average particle size of resin 100 nm, acid value 16.8 mg KOH / g, hydroxyl value acid value 16.8 mg KOH / g, non-volatile content in dispersion 45%), and the curing agent was changed to Duranate WT20-100 (Asahi Kasei Corporation, non-volatile content 100%) to obtain topcoat paint 2. In addition, the main component of topcoat paint 1 was changed to topcoat paint 3.

[0285] <Preparation of test plate> (Examples 1 to 7 and Comparative Examples 1 to 7) The paint prepared in the above <Paint Preparation> was applied to the following siding board at a rate of 0.08 kg / m2 Apply (primer coat) so that the coating is as follows: ... 2 Then, the topcoat paint 1 was applied (topcoat) so as to obtain a test panel, which was then dried under standard conditions for 7 days. Example 8 Test panels were prepared in the same manner as in Example 2, except that top coat paint 1 was changed to top coat paint 2. Example 9 Test panels were prepared in the same manner as in Example 2, except that top coat paint 1 was changed to top coat paint 3. (Base material: siding board) Photocatalytic substrate: Siding board with photocatalytic coating (Excelage Hikaricera 15 manufactured by Kemi Corporation) Substrate with inorganic coating: Siding board with inorganic resin coating (Excelage Hydrophilic Cera 15 manufactured by KM Corporation)

[0286] <Evaluation method and test results> The elongation, adhesion to substrates, frost resistance, and weather resistance were evaluated as follows. The evaluation results are shown in Tables 2 and 3. For specimens with insufficient adhesion to photocatalytic substrates or to substrates with inorganic coatings, it was determined that the multilayer film on the test plate was not suitable for coating on photocatalytic substrates or substrates with inorganic coatings, and no other evaluations were performed.

[0287] <Growth rate> The elongation of the coating film formed from the coating prepared in the above <Preparation of coating material> was determined. Specifically, the coating material was applied to a polypropylene plate with an applicator so that the dry film thickness was 30 to 60 μm, and the plate was dried at 23°C for 6 hours and 50°C for 3 days to form a coating film. Then, the plate was cut into a strip shape with a width of 10 mm and a length of 50 mm to obtain a test piece. The obtained test piece was subjected to a tensile test under conditions of a chuck distance of 30 mm, a load of 1 kN, and a speed of 5 mm / min in an environment of 23°C and 50% relative humidity, and the breaking elongation (%) of the test piece was measured. The tensile test was performed five times. The average value of the three measured values ​​excluding the minimum and maximum values ​​of the five measured values ​​was calculated, and this was taken as the elongation (%) of the coating film. The results are shown in Table 2.

[0288] <Adhesion to substrate> In accordance with JIS K 5600-5-6 (cross-cut method) and according to the above <Preparation of test plates>, the coating film of the test plate immediately after preparation on the photocatalytic substrate and inorganic substrate was cut into a 5 x 5 grid at 2 mm intervals, and a peel test after application of adhesive tape was carried out to evaluate the substrate adhesion according to the following criteria. The results are shown in Tables 2 and 3. When the evaluation result of substrate adhesion is ○ or △, the coating film has excellent adhesion to the substrate. Criteria for Adhesion to Substrate ○ Peeling area is 5% or less △ Peeling area is more than 5% and less than 15% × Peeling area exceeds 15%

[0289] <Freeze resistance> The test plate prepared on the photocatalytic substrate was placed in a freeze-thaw tester, and a freeze-thaw test was performed 300 cycles, with one cycle being [freezing in air (-20°C) for 2 hours] and [thawing in water (+20°C) for 1 hour]. Three hours after removing the test plate from the tester, the appearance of the coating was observed, and the frost resistance was evaluated according to the following criteria. The results are shown in Tables 2 and 3. If the evaluation result for frost resistance is ○ or △, the coating has excellent frost resistance. Criteria for determining frost resistance ○ No cracks or peeling visible to the naked eye or under 10x magnification △: No visible cracks or peeling, but slight cracks visible only at 10x magnification ×: Cracks or peeling visible to the naked eye

[0290] <Weather resistance> The test plate made on the photocatalytic substrate was placed in a Super UV tester, and an accelerated weather resistance test was carried out for 38 cycles (approximately 300 hours) of [6 hours of UV irradiation] - [2 hours of condensation] - [30 seconds of shower], one cycle. After removing the test plate from the tester, the appearance of the coating was observed, and the weather resistance was evaluated according to the following criteria. The results are shown in Tables 2 and 3. If the weather resistance evaluation result is ○ or △, the coating film has excellent weather resistance. ○ No cracks or peeling visible to the naked eye or under 10x magnification △: No visible cracks or peeling, but slight cracks visible only at 10x magnification ×: Cracks or peeling visible to the naked eye

[0291] <Elastic modulus of top coat> The topcoat paint was applied to a polypropylene plate with an applicator so that the dry film thickness was 30 to 60 μm, and the plate was dried at 23°C for 6 hours and 50°C for 3 days to form a coating film. The plate was then cut into a strip of 10 mm width and 50 mm length to obtain a test piece. The test piece thus obtained was subjected to a tensile test in an environment of 23°C and 50% humidity under the conditions of a chuck distance of 30 mm, a load of 1 kN, and a speed of 5 mm / min. From the obtained stress-strain curve, the slope at a load of 1.0 to 1.5 N was determined, and this was taken as the elastic modulus (N / mm 2 The results are shown in Table 3.

[0292] <Alkaline resistance> The test plate made on the photocatalytic substrate was immersed in a saturated calcium hydroxide solution for 500 hours, and immediately after taking it out, it was washed with water. After 3 hours, the adhesion of the test plate was checked and the alkali resistance was evaluated according to the following criteria. The results are shown in Table 3. ○ Peeling area is 15% or less × Peeling area exceeds 15%

[0293] [Table 3]

Claims

1. A two-component or multi-component coating composition comprising at least (A) a base agent and (B) a curing agent, The base agent (A) contains a resin (A-1) having a silanol group, and the resin (A-1) having a silanol group is a resin obtained by bonding an acrylic resin having a hydrolyzable silyl group and / or a silanol group with a polysiloxane having a hydrolyzable silyl group and / or a silanol group, and the hydrolyzable silyl group is a functional group represented by the following general formula (I): 【Chemistry 1】 (In the formula, R 1 is a monovalent organic group which is an alkyl group, an aryl group, or an aralkyl group; R 2 is a hydrolyzable group which is a halogen atom, an alkoxy group, an acyloxy group, a phenoxy group, an aryloxy group, a mercapto group, an amino group, an amido group, an aminooxy group, an iminoxy group, or an alkenyloxy group; and x is an integer of 0 to 2.) (B) The curing agent is (B-1) General formula: Si(OR) ４ [wherein R are the same or different and each R is an organic group having 1 to 8 carbon atoms] and / or a partial condensate of the organosilicate, Regarding the coating film formed from the coating composition, the silicon content of the resin constituting the coating film is 5.0 to 15.0 mass %, A coating composition characterized in that a coating film formed from the coating composition has an elongation percentage of 15% or more at 23°C.

2. The coating composition according to claim 1, wherein the resin having a silanol group (A-1) is a composite resin formed by bonding a hydrophilic group-containing polyurethane having a hydrolyzable silyl group and / or a silanol group and an acrylic resin having a hydrolyzable silyl group and / or a silanol group via a polysiloxane having a hydrolyzable silyl group and / or a silanol group, and the hydrolyzable silyl group is a functional group represented by the general formula (I).

3. A method for repairing an architectural exterior material, comprising the steps of: removing contaminants on an old coating film on the surface of the architectural exterior material without peeling or removing the old coating film, applying the coating composition described in claim 1 or 2 onto the old coating film to form an undercoat coating film; and applying a topcoat paint onto the undercoat coating film to form a topcoat coating film.

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