Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D1/00—Processes for applying liquids or other fluent materials
  • B05D1/36—Successively applying liquids or other fluent materials, e.g. without intermediate treatment
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B05—SPRAYING OR ATOMISING IN GENERAL; APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D—PROCESSES FOR APPLYING FLUENT MATERIALS TO SURFACES, IN GENERAL
  • B05D7/00—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials
  • B05D7/24—Processes, other than flocking, specially adapted for applying liquids or other fluent materials to particular surfaces or for applying particular liquids or other fluent materials for applying particular liquids or other fluent materials
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
  • C09D175/04—Polyurethanes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D201/00—Coating compositions based on unspecified macromolecular compounds
  • C09D201/02—Coating compositions based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups
  • C09D201/06—Coating compositions based on unspecified macromolecular compounds characterised by the presence of specified groups, e.g. terminal or pendant functional groups containing oxygen atoms
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D5/00—Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
  • C09D5/02—Emulsion paints including aerosols

Definitions

• the present invention relates to a method for producing a water-based coating composition and coated articles.
• Patent Document 1 Conventionally, solvent-based paints have been used to paint automobiles because they tend to improve sharpness and finished appearance. In recent years, interest in the environment has increased, and the demand for water-based paints has increased in place of solvent-based paints. (For example, Patent Document 1)
• An object of the present invention is to provide a water-based coating composition that provides a coating film with excellent water resistance. Another object of the present invention is to provide a method for producing a coated article having a coating film formed from the above coating composition.
• the present invention provides the following aspects [1] to [8].
• a water-based coating composition used as a primer surfacer [ 1].
• An aqueous coating composition for forming a clear coating film The content of the silane coupling agent is 1.2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a1) and the polyisocyanate compound (b1).
• the aqueous primer surfacer (X) comprises a first main agent (A1) containing a first hydroxyl group-containing resin (a11) and a first aqueous solvent (a21); and a first curing agent (B1) containing a first polyisocyanate compound (b11) and a first organic solvent (b21) having no hydroxyl group,
• the silane coupling agent is contained in at least one of the first main agent (A1) and the first curing agent (B1),
• the content of the silane coupling agent is 1 part by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the total solid content of the first hydroxyl-containing resin (a11) and the first polyisocyanate compound (b11).
• the aqueous clear coating composition (Z) comprises a second main agent (A2) containing a second hydroxyl group-containing resin (a12) and a second aqueous solvent (a22), and a second curing agent (B2) containing a second polyisocyanate compound (b12) and a second organic solvent (b22) having no hydroxyl group,
• the silane coupling agent is contained in at least one of the second main agent (A2) and the second curing agent (B2),
• the content of the silane coupling agent is 1.2 parts by mass or more and 10 parts by mass with respect to 100 parts by mass of the total solid content of the second hydroxyl group-containing resin (a12) and the second polyisocyanate compound (b12).
• a water-based coating composition that provides a coating film with excellent water resistance.
• a method for producing a coated article having a coating film formed from the aqueous coating composition is also provided.
• the water-based coating composition according to this embodiment is a two-component type containing a main agent (A) and a curing agent (B).
• the main agent (A) contains a hydroxyl group-containing resin (a1) and an aqueous solvent (a2).
• the curing agent (B) contains a polyisocyanate compound (b1) and an organic solvent (b2) having no hydroxyl group.
• At least one of the main agent (A) and the curing agent (B) further contains a silane coupling agent having one or more epoxy groups (hereinafter referred to as an epoxy group-containing silane coupling agent).
• the hydroxyl group-containing resin (a1) contained in the main agent (A) is crosslinked by the polyisocyanate compound (b1) to obtain a cured coating film.
• the epoxy group-containing silane coupling agent also reacts with at least one of the hydroxyl group-containing resin (a1) and the polyisocyanate compound (b1) to form a crosslinked structure. This increases the crosslink density of the cured coating film. As a result, water resistance is improved.
• the water-based coating composition according to the present embodiment includes, for example, a coating for forming a base coating (so-called water-based primer surfacer), a coating for forming a colored base coating (colored base coating composition), and a coating for forming a clear coating. It is used as a paint (aqueous clear paint composition).
• a coating for forming a base coating so-called water-based primer surfacer
• a coating for forming a colored base coating colored base coating composition
• a coating for forming a clear coating It is used as a paint (aqueous clear paint composition).
• a coating for forming a multilayer coating film the water resistance of the entire multilayer coating film is improved by using the water-based coating composition according to the present embodiment as a coating material for forming at least one layer.
• the silane coupling agent also improves the adhesion between the cured coating film and the object to which it is applied. Therefore, the water-based coating composition is particularly suitable as a water-based primer surfacer for automobiles. This is because the primer surfacer is applied directly to the object to be coated.
• the aqueous coating compositions are also suitable for forming various coatings for repairing automotive coatings. This is because the coating film for repair is required to have high adhesion to the existing coating film in addition to the object to be coated.
• a water-based primer surfacer containing an epoxy group-containing silane coupling agent and a water-based clear coating composition containing an epoxy group-containing silane coupling agent are used in combination. preferably.
• water-based primer surfacer The main agent (A) contained in the water-based primer surfacer (X) is called the first main agent (A1), and the curing agent (B) is called the first curing agent (B1).
• the hydroxyl group-containing resin (a1) contained in the first main agent (A1) is called the first hydroxyl group-containing resin (a11), and the aqueous solvent (a2) is called the first aqueous solvent (a21).
• the polyisocyanate compound (b1) contained in the first curing agent (B1) is called the first polyisocyanate compound (b11), and the organic solvent (b2) is called the first organic solvent (b21).
• the water-based coating composition for forming a clear coating film is hereinafter referred to as the water-based clear coating composition (Z).
• the main agent (A) contained in the aqueous clear coating composition (Z) is called the second main agent (A2), and the curing agent (B) is called the second curing agent (B2).
• the hydroxyl group-containing resin (a1) contained in the second main agent (A2) is called the second hydroxyl group-containing resin (a12), and the aqueous solvent (a2) is called the second aqueous solvent (a22).
• the polyisocyanate compound (b1) contained in the second curing agent (B2) is called a second polyisocyanate compound (b12), and the organic solvent (b2) is called a second organic solvent (b22).
• the first main agent (A1) and the second main agent (A2) are collectively referred to as the main agent (A).
• the first curing agent (B1) and the second curing agent (B2) are collectively referred to as curing agent (B).
• the first hydroxyl-containing resin (a11) and the second hydroxyl-containing resin (a12) are collectively referred to as hydroxyl-containing resin (a1).
• the first aqueous solvent (a21) and the second aqueous solvent (a22) are collectively referred to as the aqueous solvent (a2).
• the first polyisocyanate compound (b11) and the second polyisocyanate compound (b12) are collectively referred to as polyisocyanate compound (b1).
• the first organic solvent (b21) and the second organic solvent (b22) are collectively referred to as organic solvent (b2).
• the water-based paint composition is prepared using a method commonly used by those skilled in the art.
• the water-based paint composition is prepared by mixing each component by, for example, a kneading mixing method using a kneader or rolls or a dispersing mixing method using a sand grind mill or disper.
• Silane coupling agents typically have both reactive silyl groups and organic functional groups.
• the epoxy group-containing silane coupling agent has one or more epoxy groups as organic functional groups.
• the epoxy group-containing silane coupling agent may have two or more epoxy groups.
• the epoxy group is a three-membered ring (oxirane ring) with an ether bond.
• the epoxy group has high reactivity and reacts with the hydroxyl group-containing resin (a1) and/or the polyisocyanate compound (b1). Therefore, the crosslink density of the resulting cured coating film is increased.
• the epoxy group is represented, for example, by the following structural formula (1).
• the epoxy group may be alicyclic.
• the alicyclic epoxy group includes, for example, an epoxycyclohexyl group represented by the following structural formula (2).
• the epoxy group-containing silane coupling agent may have other organic functional groups.
• the epoxy group-containing silane coupling agent when the epoxy group-containing silane coupling agent is contained in the main agent (A), it is desirable that the isocyanate group is not contained as an organic functional group. This is because if the hydroxyl group-containing resin (a1) and the epoxy group-containing silane coupling agent react with each other before the main agent (A) and the curing agent (B) are mixed, the crosslink density of the cured coating film is unlikely to increase. be.
• the organic functional groups include hydroxyl groups and amino groups (primary, secondary and tertiary amino groups, and amino groups to which epoxy groups are bonded). should not be included.
• polyisocyanate compound (b1) and the epoxy group-containing silane coupling agent react with each other before the main agent (A) and the curing agent (B) are mixed, the crosslink density of the cured coating film is unlikely to increase.
• Other desirable organic functional groups include, for example, acrylamide, acryloyl, methacryloyl, allyl, vinyl, styryl and mercapto groups.
• the reactive silyl group is not particularly limited as long as it generates a silanol group by hydrolysis.
• Examples of reactive silyl groups include trialkoxysilyl groups (the number of carbon atoms contained in the alkoxy group is preferably 1 to 7), dialkoxyalkylsilyl groups (the number of carbon atoms contained in the alkoxy group is preferably 1 to 7, alkyl The number of carbon atoms contained in the group is preferably 1 to 7), more specifically, trimethoxysilyl group, triethoxysilyl group, tripropoxysilyl group, tris(2-methoxyethoxy)silyl group, dimethoxyalkyl silyl group, diethoxyalkylsilyl group, dipropoxyalkylsilyl group, bis(2-methoxyethoxy)alkylsilyl group (the above alkyl group may be a linear or branched alkyl group having 1 to 7 carbon atoms ).
• the multiple reactive silyl groups may be the same or different. Among them, a trialkoxysilyl group is preferable, a trialkoxysilyl group having 1 to 3 carbon atoms contained in the alkoxy group is more preferable, and a triethoxysilyl group is particularly preferable, because the water resistance can be more easily improved.
• the epoxy group-containing silane coupling agent is contained in at least one of the main agent (A) and the curing agent (B). Among them, the epoxy group-containing silane coupling agent is preferably contained in the curing agent (B) in terms of excellent miscibility with the polyisocyanate compound (b1).
• the content of the epoxy group-containing silane coupling agent may be 1 part by mass or more and 1.1 parts by mass with respect to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a1) and the polyisocyanate compound (b1). parts or more, and may be 1.2 parts by mass or more.
• the content of the epoxy group-containing silane coupling agent may be 10 parts by mass or less, and 8 parts by mass or less, relative to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a1) and the polyisocyanate compound (b1). and may be 6 parts by mass or less.
• the content of the epoxy group-containing silane coupling agent is 1 part by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a1) and the polyisocyanate compound (b1). be.
• the content of the epoxy group-containing silane coupling agent is 100 of the total solid content of the first hydroxyl group-containing resin (a11) and the first polyisocyanate compound (b11). It may be 1 part by mass or more, 1.1 parts by mass or more, or 1.2 parts by mass or more.
• the content of the epoxy group-containing silane coupling agent may be 8 parts by mass or less with respect to 100 parts by mass of the total solid content of the first hydroxyl group-containing resin (a11) and the first polyisocyanate compound (b11), It may be 6 parts by mass or less, and may be 5 parts by mass or less.
• the content of the epoxy group-containing silane coupling agent contained in the aqueous primer surfacer (X) is 100 parts by mass of the total solid content of the first hydroxyl group-containing resin (a11) and the first polyisocyanate compound (b11). is 1 part by mass or more and 8 parts by mass or less.
• the content of the epoxy group-containing silane coupling agent is the total solids of the second hydroxyl-containing resin (a12) and the second polyisocyanate compound (b12). It may be 1.2 parts by mass or more, 1.3 parts by mass or more, or 2 parts by mass or more per 100 parts by mass.
• the content of the epoxy group-containing silane coupling agent may be 10 parts by mass or less with respect to 100 parts by mass of the total solid content of the second hydroxyl group-containing resin (a12) and the second polyisocyanate compound (b12), It may be 8 parts by mass or less, and may be 6 parts by mass or less.
• the content of the epoxy group-containing silane coupling agent contained in the aqueous clear coating composition (Z) is 100 of the total solid content of the second hydroxyl group-containing resin (a12) and the second polyisocyanate compound (b12). It is 1.2 parts by mass or more and 10 parts by mass or less with respect to parts by mass.
• the water-based coating composition may contain silane coupling agents other than the epoxy group-containing silane coupling agent.
• the ratio of the epoxy group-containing silane coupling agent to the total silane coupling agent may be 80% by mass or more, or 90% by mass or more.
• other silane coupling agents contained in the main agent (A) desirably do not have isocyanate groups.
• Other silane coupling agents contained in the curing agent (B) desirably do not have hydroxyl groups and amino groups (including primary, secondary and tertiary amino groups, and epoxy group-bonded amino groups).
• the main agent (A) contains a hydroxyl group-containing resin (a1) and an aqueous solvent (a2).
• the solid content of the main agent (A) is not particularly limited.
• the solid content concentration of the main agent (A) is, for example, 30% by mass or more and 60% by mass or less.
• the hydroxyl group-containing resin (a1) is in the form of an emulsion dispersed in the aqueous solvent (a2).
• the particle size of the hydroxyl group-containing resin (a1) in the main agent (A) is not particularly limited.
• the average particle size of the hydroxyl group-containing resin (a1) may be 0.01 ⁇ m or more, and may be 0.05 ⁇ m or more, in terms of ease of viscosity control and appearance of the resulting coating film.
• the average particle size of the hydroxyl group-containing resin (a1) may be 1.0 ⁇ m or less, and may be 0.5 ⁇ m or less.
• the average particle size of the hydroxyl group-containing resin (a1) is 0.01 ⁇ m or more and 1.0 ⁇ m or less.
• the average particle size is the 50% size (median size, D50) in the volume-based particle size distribution measured by the dynamic light scattering method.
• the solid content concentration of the hydroxyl group-containing resin (a1) may be 15 mass % or more, 20 mass % or more, or 25 mass % or more of the total solid content contained in the main agent (A).
• the solid content concentration of the hydroxyl group-containing resin (a1) may be 95% by mass or less, 85% by mass or less, or 80% by mass or less of the total solids contained in the main agent (A).
• the solid content concentration of the hydroxyl group-containing resin (a1) is 15 mass % or more and 95 mass % or less of the total solid content contained in the main agent (A).
• the hydroxyl value of the hydroxyl-containing resin (a1) may be 5 mgKOH/g or more, or may be 50 mgKOH/g or more.
• the hydroxyl value of the hydroxyl-containing resin (a1) may be 200 mgKOH/g or less, and may be 150 mgKOH/g or less.
• the hydroxyl value of the hydroxyl-containing resin (a1) is 5 mgKOH/g or more and 200 mgKOH/g or less.
• the acid value of the hydroxyl group-containing resin (a1) is not particularly limited, and may be 5 mgKOH/g or more, or 10 mgKOH/g or more.
• the acid value of the hydroxyl group-containing resin (a1) may be 100 mgKOH/g or less, and may be 50 mgKOH/g or less.
• the hydroxyl group-containing resin (a1) has an acid value of 5 mgKOH/g or more and 100 mgKOH/g or less.
• the number average molecular weight of the hydroxyl group-containing resin (a1) is not particularly limited, and may be 1,000 or more, 2,000 or more, or 3,000 or more.
• the number average molecular weight of the hydroxyl group-containing resin (a1) may be 100,000 or less, 50,000 or less, or 10,000 or less.
• the hydroxyl group-containing resin (a1) has a number average molecular weight of 1,000 or more and 100,000 or less.
• the hydroxyl value and acid value are both based on the solid content and can be measured according to JIS K 0070.
• a number average molecular weight is a styrene homopolymer conversion value measured using a gel permeation chromatography.
• the hydroxyl group-containing resin (a1) is not particularly limited as long as it has one or more, preferably two or more hydroxyl groups.
• hydroxyl group-containing resins (a1) include acrylic polyols, polyester polyols, polyether polyols, polyurethane polyols, and polycarbonate polyols. Among them, acrylic polyols are preferable in that various physical properties such as the appearance, weather resistance, and chemical resistance of the coating film to be obtained are likely to be improved.
• the hydroxyl group-containing resin (a1) is obtained, for example, by emulsion polymerization of one or more raw material monomers.
• Emulsion polymerization is carried out by a method commonly practiced by those skilled in the art. Specifically, an emulsifier is mixed with an aqueous medium containing an organic solvent such as alcohol as necessary, and the raw material monomers and the polymerization initiator are added dropwise while the resulting mixture is heated and stirred.
• an emulsified mixture obtained by previously emulsifying raw material monomers, an emulsifier and water may be dropped into an aqueous medium.
• the aqueous medium may be the same as or different from the aqueous solvent (a2).
• Emulsions of acrylic polyols are produced by, for example, emulsion polymerization of a raw material monomer mixture containing (meth)acrylic acid alkyl ester monomers, acid group-containing ethylenically unsaturated monomers, hydroxyl group-containing ethylenically unsaturated monomers, and styrene monomers. can get.
• aqueous solvents include various types of water such as pure water, ion-exchanged water, tap water, and industrial water.
• the main agent (A) may contain an organic solvent together with the aqueous solvent.
• organic solvents include diethylene glycol dibutyl ether (dibutyl diglycol), dipropylene glycol dimethyl ether, butyl acetate, ethyl diglycol acetate, propylene glycol methyl ether acetate, n-butyl alcohol, methoxypropanol, diethylene glycol monobutyl ether, ethylene glycol monobutyl ether.
• the main agent (A) may contain a resin containing no hydroxyl group, if necessary.
• the main agent (A) may also contain various additives, if necessary, in addition to the hydroxyl group-containing resin (a1) and the aqueous solvent (a2).
• Additives include, for example, dispersants, defoamers, ultraviolet absorbers, hindered amine light stabilizers, antioxidants, viscosity modifiers, surface modifiers, coalescing agents, rust inhibitors and thickeners. . Among them, it is preferable to include a viscosity modifier and/or a surface modifier, since the appearance of the resulting coating film is likely to be further improved.
• Viscosity modifiers include, for example, crosslinked resin particles (polymer compounds having a crosslinked structure in the molecule), inorganic viscosity agents, cellulose derivatives, and urethane association type viscosity agents. These are used singly or in combination of two or more.
• the amount of the viscosity modifier may be, for example, 0.1% by mass or more, or 0.5% by mass or more, based on the solid content of the hydroxyl-containing resin (a1).
• the amount of the viscosity modifier may be 50% by mass or less, or 30% by mass or less, of the solid content of the hydroxyl-containing resin (a1). In one aspect, the amount of the viscosity modifier is 0.1 mass % or more and 50 mass % or less of the solid content of the hydroxyl group-containing resin (a1).
• the amount of the surface conditioner may be, for example, 0.1% by mass or more, or 0.2% by mass or more, based on the solid content of the hydroxyl-containing resin (a1).
• the amount of the surface conditioner may be, for example, 10% by mass or less, or 8% by mass or less of the solid content of the hydroxyl-containing resin (a1).
• the amount of the surface conditioner is 0.1 mass % or more and 10 mass % or less of the solid content of the hydroxyl group-containing resin (a1).
• the main agent (A) can be prepared by mixing the above components by methods known to those skilled in the art. Mixing methods include the same methods as those for preparing the water-based paint composition.
• the curing agent (B) contains a polyisocyanate compound (b1) and an organic solvent (b2) having no hydroxyl group.
• the solid content of the curing agent (B) is not particularly limited.
• the solid content concentration of the curing agent (B) is, for example, 20% by mass or more and 70% by mass or less.
• the polyisocyanate compound (b1) is not particularly limited as long as it has an average of two or more isocyanate groups per molecule.
• polyisocyanates include aliphatic diisocyanates such as hexamethylene diisocyanate, pentamethylene diisocyanate, tetramethylene diisocyanate and trimethylhexamethylene diisocyanate; Isocyanates; aromatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, tolylene diisocyanate, and xylylene diisocyanate; modified products thereof (e.g., urethane compounds, carbodiimides, uretdione, uretonimine, biuret forms, isocyanurates, etc.) .
• the content of the polyisocyanate compound (b1) may be, for example, 20% by mass or more, or 30% by mass or more, of the total solid content of the curing agent (B).
• the organic solvent (b2) is not particularly limited as long as it does not have a hydroxyl group.
• examples of the organic solvent (b2) include ethylene glycol dimethyl ether (DMM), ethylene glycol diethyl ether, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol divinyl ether, diethylene glycol ethyl methyl ether, diethylene glycol isopropyl methyl ether, diethylene glycol butyl methyl ether, and triethylene.
• Glycol dimethyl ether triethylene glycol divinyl ether, tetraethylene glycol diethyl ether, propylene glycol dimethyl ether, propylene glycol diethyl ether, propylene glycol di-n-propyl ether, propylene glycol diisopropyl ether, propylene glycol di-n-butyl ether, propylene glycol diisobutyl ether , propylene glycol diallyl ether, propylene glycol diphenyl ether, dipropylene glycol dimethyl ether (DPDM), dipropylene glycol diethyl ether, dipropylene glycol di-n-butyl ether, dipropylene glycol diisobutyl ether, dipropylene glycol diallyl ether, tripropylene glycol dimethyl ether, Tripropylene glycol diethyl ether, tripropylene glycol di-n-butyl ether, tripropylene glycol diiso
• the curing agent (B) may contain curing agents other than the polyisocyanate compound (b1).
• the content of other curing agents is, for example, 10% by mass or less of the total solid content of all curing agents.
• Curing agent (B) can be prepared by mixing the above components by methods known to those skilled in the art. Mixing methods include the same methods as those for preparing the water-based paint composition.
• a diluent component (C) may be further mixed with the aqueous coating composition.
• the diluent component (C) include the same as the aqueous solvent (a2).
• the diluent component (C) may be the same as or different from the aqueous solvent (a2).
• the amount of the diluent component (C) mixed is appropriately set in consideration of the viscosity of the water-based coating composition, the coating method, and the like.
• the amount of the diluent component (C) mixed is, for example, 10 parts by mass or more and 70 parts by mass or less with respect to 100 parts by mass of the solid content of the hydroxyl-containing resin (a1).
• the aqueous primer surfacer (X) may further contain a pigment (D).
• the content of the pigment (D) may be 100 parts by mass or more, and may be 120 parts by mass or more with respect to 100 parts by mass of the resin solid content contained in the main agent (A1) of the water-based primer surfacer (X).
• the content of the pigment (D) may be 300 parts by mass or less, and may be 200 parts by mass or less with respect to 100 parts by mass of the resin solid content contained in the main agent (A1) of the aqueous primer surfacer (X).
• the content of the pigment (D) is 100 parts by mass or more and 300 parts by mass or less with respect to 100 parts by mass of the resin solid content contained in the main agent (A1) of the aqueous primer surfacer (X).
• the pigment (D) is not particularly limited.
• the pigment (D) include coloring pigments such as titanium dioxide, carbon black, iron oxide and copper phthalocyanine blue; luster pigments such as aluminum flakes and mica flakes; calcium carbonate, clay, talc, barium oxide, silica and the like.
• Extender pigments rust preventive pigments such as aluminum tripolyphosphate, aluminum phosphomolybdate, and zinc phosphate;
• At least an extender pigment is included from the viewpoint of the abrasiveness and film-forming properties of the base coating film.
• the proportion of the extender pigment may be 30% by mass or more, or 40% by mass or more, relative to the total of 100 parts by mass of all pigments.
• the proportion of the extender pigment is 100% by mass or less, and may be 70% by mass or less, with respect to a total of 100 parts by mass of all pigments.
• the proportion of the extender pigment is 30% by mass or more and 100% by mass or less with respect to a total of 100 parts by mass of all pigments.
• a coated article is prepared by applying a water-based primer surfacer (X) to an object to be coated to form a base coat (I), and coating a water-based colored base coating composition (Y) on the base coat. a step (II) of forming a colored base coating film; and a step (III) of coating the aqueous clear coating composition (Z) on the colored base coating film to form a clear coating film.
• At least one of the water-based primer surfacer (X) and the water-based clear coating composition (Z) contains a silane coupling agent having one or more epoxy groups. This improves the water resistance of the entire multi-layer coating film.
• both the aqueous primer surfacer (X) and the aqueous clear coating composition (Z) preferably contain an epoxy group-containing silane coupling agent.
• Step of Forming Base Coat Film In this step, a water-based primer surfacer (X) is applied to the object to be coated to form a base coat film.
• the first hydroxyl group-containing resin (a11) and the first aqueous solvent (a21) are mixed to prepare the first main agent (A1).
• the first curing agent (B1) is prepared by mixing the first polyisocyanate compound (b11) and the first organic solvent (b21) having no hydroxyl group.
• the obtained first main agent (A1) and first curing agent (B1) are mixed to prepare a water-based primer surfacer (X).
• Mixing of the first main agent (A1) and the first curing agent (B1) is performed immediately before coating.
• the first main agent (A1) and the first curing agent (B1) may be supplied to the coating apparatus, or may be mixed within the coating apparatus.
• the mixing method is as described above.
• the epoxy group-containing silane coupling agent is added to at least one of the first main agent (A1) and the first curing agent (B1).
• the silane coupling agent is added in an amount of 1 part by mass or more and 8 parts by mass or less with respect to 100 parts by mass of the total solid content of the first hydroxyl group-containing resin (a11) and the first polyisocyanate compound (b11). be.
• the prepared aqueous primer surfacer (X) is applied onto the substrate.
• the coating amount of the water-based primer surfacer (X) is not particularly limited, and is appropriately set according to the performance required for the coating film.
• the water-based primer surfacer (X) is applied, for example, so that the thickness of the undercoating film after curing is 20 ⁇ m or more and 100 ⁇ m or less.
• the method of coating the water-based primer surfacer (X) is not particularly limited.
• coating methods include air spray coating, airless spray coating, rotary atomization coating, and curtain coating. These methods may be combined with electrostatic coating. In the case of repair, air spray coating is preferred because local coating is easy. Coating may be performed multiple times.
• the water-based primer surfacer (X) After the water-based primer surfacer (X) is applied, it is heated to harden the coating film. Curing conditions are appropriately set according to the coating amount and composition. Curing is performed, for example, at a temperature of 40° C. or higher and 70° C. or lower for about 30 to 60 minutes. After curing, the basecoat is usually sanded and degreased. Polishing is performed using sandpaper or the like.
• the target part of the object to be coated and its surroundings are polished, and unevenness is filled with putty. Subsequently, the part is polished again.
• the shape of the object to be coated is not particularly limited.
• the object to be coated may be in the form of a flat plate or may have a three-dimensional shape.
• the material of the object to be coated is also not particularly limited. Examples of the material of the object to be coated include metal, resin, and glass. Metals include, for example, iron, copper, aluminum, tin, zinc, or alloys thereof.
• the metal object to be coated may be surface-treated. Examples of surface treatment include phosphate treatment, chromate treatment, zirconium chemical conversion treatment, and composite oxide treatment.
• the metal object to be coated may be further coated with an electrodeposition paint after the surface treatment.
• the electrodeposition paint may be cationic or anionic.
• resins examples include polypropylene resins, polycarbonate resins, urethane resins, polyester resins, polystyrene resins, ABS resins, vinyl chloride resins, and polyamide resins.
• the resin-made object to be coated is preferably degreased.
• objects to be coated include car bodies such as passenger cars, trucks, motorcycles, and buses, or parts thereof.
• Step of forming a colored base coating film the water-based colored base coating composition (Y) is applied onto the base coating film to form a colored base coating film.
• the application of the water-based colored base coating composition (Y) may be carried out multiple times.
• the aqueous colored base coating composition (Y) may be of the curing type or of the lacquer type.
• the aqueous colored base coating composition (Y) further contains a pigment.
• Pigments include, for example, color pigments and/or luster pigments exemplified for pigment (D).
• the curable type water-based colored base coating composition (Y) contains a curable resin (for example, the above main agent (A)) and a curing agent (for example, the above curing agent (B)), and is cured by heating. A film is formed.
• the curable type aqueous colored base coating composition (Y) may further contain a silane coupling agent (for example, an epoxy group-containing silane coupling agent).
• the lacquer-type water-based colored base paint composition (Y) contains water, an organic solvent, and a binder resin dissolved or dispersed therein, and volatilization of the water and the organic solvent forms a cured coating film.
• concentration of the binder resin is not particularly limited, and is appropriately set according to the composition and application.
• the binder resin is not particularly limited.
• binder resins include acrylic resins, amino alkyd resins, alkyd resins, amino resins, isocyanate resins, epoxy resins, vinyl chloride resins, cashew resins, silicone resins, styrene resins, styrenated alkyd resins, cellulose resins (e.g., cellulose nitrate, etc.), urea resins, vinyl resins, phenolic resins, phthalic acid resins, fluororesins, polyester resins, unsaturated polyester resins, and modified resins thereof (e.g., rosin-modified, phenol-modified, epoxy resin-modified, styrene-modified , acrylic modification, urethane modification). These are used singly or in combination of two or more.
• organic solvents include naphtha, xylene, toluene, and acetone.
• the method of coating the water-based colored base coating composition (Y) is not particularly limited, and includes the same method as for the water-based primer surfacer (X).
• the coating amount of the water-based colored base coating composition (Y) is not particularly limited, and, for example, it is applied so that the thickness of the colored base coating film after curing is 10 ⁇ m or more and 100 ⁇ m or less. After coating, the coating is cured. Curing conditions are appropriately set according to the composition of the aqueous colored base coating composition (Y).
• Method for preparing aqueous clear coating composition (Z) The second hydroxyl group-containing resin (a12) and the second aqueous solvent (a22) are mixed to prepare the second main agent (A2). Separately, the second curing agent (B2) is prepared by mixing the second polyisocyanate compound (b12) and the second organic solvent (b22) having no hydroxyl group.
• the obtained second main agent (A2) and second curing agent (B2) are mixed to prepare an aqueous clear coating composition (Z).
• Mixing of the second main agent (A2) and the second curing agent (B2) is performed immediately before coating.
• the second main agent (A2) and the second curing agent (B2) may be supplied to the coating device after being mixed, or may be mixed within the coating device.
• the mixing method is as described above.
• the epoxy group-containing silane coupling agent is added to at least one of the second main agent (A2) and the second curing agent (B2).
• the silane coupling agent is 1.2 parts by mass or more and 10 parts by mass or less with respect to 100 parts by mass of the total solid content of the second hydroxyl group-containing resin (a12) and the second polyisocyanate compound (b12). added.
• the prepared water-based clear coating composition (Z) is applied onto the water-based colored base coating film.
• the coating amount of the water-based clear coating composition (Z) is not particularly limited, and is appropriately set according to the performance required for the coating film.
• the water-based clear coating composition (Z) is applied, for example, so that the thickness of the clear coating film after curing is 20 ⁇ m or more and 100 ⁇ m or less.
• the method of coating the water-based clear coating composition (Z) is not particularly limited, and includes the same method as for the water-based primer surfacer (X). Among them, air spray coating is preferable. Coating may be performed multiple times.
• aqueous clear coating composition (Z) After the aqueous clear coating composition (Z) is applied, it is heated to cure the coating film. Curing is performed, for example, at a temperature of 40° C. or higher and 100° C. or lower for about 15 to 60 minutes. In this way, a coated article is obtained which comprises the primer coating, the colored base coating and the clear coating in this order.
• Polyisocyanate compound A Barnock DNW-5500 (manufactured by DIC)
• Polyisocyanate compound B Bayhydur ultra 304 (manufactured by Sumika Covestro)
• Silane coupling agent A 3-glycydoxypropyltrimethoxysilane
• Silane coupling agent B 3-glycydoxypropyltriethoxysilane
• Silane coupling agent C N-phenyl-3-aminopropyltrimethoxysilane
• the sample was then placed in a metal container and sealed. This metal container was stored in a constant temperature room at 50° C. for 30 days. After that, the metal container was taken out from the thermostatic chamber and the liquid temperature was adjusted to 23°C. Subsequently, the time (T (seconds)) from pulling up to discharging the sample was measured in the same manner as described above. TT 0 was calculated and evaluated according to the following criteria.
• Gardner color number is 1 Acceptable: 2 to 3 Gardner colors Impossible: 4 or more Gardner colors
• curing agents HA to HE contained epoxy group-containing silane coupling agents, storage stability was as good as curing agent Ha containing no silane coupling agent.
• the comparative curing agent Hb containing a silane coupling agent having an amino group instead of an epoxy group is inferior in storage stability.
• Example 1 A water-based primer surfacer (X), a water-based colored base coating composition (Y) and a water-based clear coating composition (Z) were prepared in the following manner to produce coated articles.
• the first main agent (A1) containing the pigment (D) As the first main agent (A1) containing the pigment (D), nax E-CUBE WB Plasaf Vita Gray (manufactured by Nippon Paint Co., Ltd., solid content: about 56%) was prepared.
• the first main agent (A1) contains acrylic polyol in the form of an emulsion as the hydroxyl group-containing resin (a11), and contains pure water as the aqueous solvent (a21).
• the solid content concentration of the hydroxyl group-containing resin (a11) is 24.4% of the total solid content contained in the first main agent (A1).
• the curing agent (B1) As the first curing agent (B1), the curing agent HA prepared above was prepared. Pure water was prepared as the diluent component (C).
• a primer surfacer was prepared by mixing 100 parts of the first main agent (A1), 12.5 parts of the curing agent HA, and an appropriate amount of the diluent component (C) using a disper.
• the content of the silane coupling agent was 1.18 parts by mass with respect to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a11) and the polyisocyanate compound (b11).
• nax E-CUBE WB412 Silent Black manufactured by Nippon Paint Co., Ltd., solid content about 22%) 100 parts, nax E-CUBE WB 911 S-binder (auxiliary agent, Japan A lacquer-type base coat paint was prepared by mixing 50 parts of Nax E-CUBE WB R20 standard diluent (diluent component, manufactured by Nippon Paint Co., Ltd.).
• the curing agent HA prepared above was prepared. Pure water was prepared as the diluent component (C).
• a water-based clear coating composition (Z) was prepared by mixing 100 parts of the second main agent (A2), 50 parts of the curing agent HA, and an appropriate amount of the diluent component (C) using a disper.
• the content of the silane coupling agent was 1.35 parts by mass with respect to 100 parts by mass of the total solid content of the hydroxyl group-containing resin (a12) and the polyisocyanate compound (b12).
• Examples 2-8, Comparative Examples 1-2 A water-based primer surfacer (X) and a water-based clear coating composition were prepared in the same manner as in Example 1, except that the types of the first curing agent (B1) and the second curing agent (B2) were changed as shown in Table 2. (Z) was prepared to produce a coated article.
• a water-based coating composition that provides a coating film with excellent water resistance. Therefore, the water-based coating composition is suitable for coating of automobiles, especially coating for automobile repair.

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