JP6470183B2 - Multi-layer coating formation method - Google Patents

Description

(Cross-reference of related fields)
This application claims the benefit of priority of Japanese Patent Application No. 2013-255844, filed on December 11, 2013, which is incorporated herein by reference in its entirety.

  The present invention relates to a method for forming a multilayer coating film capable of forming a coating film having excellent chipping resistance, adhesion, finish, weather resistance and gasohol resistance against a metal member and a plastic member. About.

  Generally, an automobile body has a metal member that forms the body and a plastic member such as a bumper.

  In such car body painting, conventionally, a metal member and a plastic member, separate paints suitable for the respective members, and a separate painting process are applied, and then the plastic member is attached to the metal member. ing.

  However, in recent years, in order to reduce the equipment cost in the manufacturing process of the automobile body and to match the color tone of the metal member and the plastic member, there is a demand for a method of painting with the plastic member mounted on the metal member.

  For example, Patent Document 1 discloses a method for painting an automobile body in which a polypropylene resin member is assembled to a metal steel plate.

  However, since the intermediate coating material disclosed in Patent Document 1 is not conductive, a conductive primer coating must be applied to the polypropylene member. That is, in Patent Document 1, conductive primer paint → intermediate paint → top coat paint is applied in order to the polypropylene member, and intermediate coat → top coat paint is applied in order to the metal member. That is, since the plastic member and the metal member are not all coated with the same paint and the same coating process, it is not sufficient in terms of cost reduction and color matching.

  Patent Document 2 discloses a water-based coating composition containing a specific anionic urethane resin emulsion and a specific urethane resin. However, when the paint is applied to a metal member and a plastic member, even if there is no problem with chipping resistance and light transmittance, it is difficult to say that the adhesion to the plastic member is sufficient as compared with the aqueous conductive primer.

  In Patent Document 3, at least one aqueous resin (B) selected from an aqueous polyolefin resin (A), an aqueous polyurethane resin, and an aqueous acrylic resin, a polyester resin (C), and a cross-linking agent (D) at a specific ratio. An aqueous primer coating composition comprising is disclosed. However, when the paint is applied to a metal member and a plastic member, it is difficult to say that the chipping resistance and the light transmittance are sufficient as compared with the water-based intermediate coating paint, even though the adhesion to the plastic member is not a problem.

JP 2012-213692 A JP 2005-330339 A WO2007 / 66827

  The present invention has been made in consideration of these points, and is capable of forming a coating film having excellent chipping resistance, adhesion, finish, weather resistance, and gasohol resistance against metal members and plastic members. It aims at providing the layer coating-film formation method.

  As a result of intensive studies to achieve the above-mentioned object, the inventors of the present invention have developed a three-coat one-bake method that sequentially coats a water-based first colored paint, a water-based second colored paint, and a clear paint on an object to be coated. In the layer coating film forming method, as the water-based first colored paint (X), a non-chlorinated polyolefin resin (A), a specific water-based polyurethane resin (B), a block polyisocyanate compound (C) having a nonionic hydrophilic group, and The average light transmittance at a wavelength of 360 to 420 nm of a cured coating film having a thickness of 5 μm obtained by applying and curing the aqueous first colored paint (X) using a paint containing a conductive pigment (D) The present inventors have found that the above-mentioned problems can be solved by a method for forming a multilayer coating film characterized by a content of less than 1%, and have completed the present invention.

That is, the present invention provides the following multilayer coating film forming method.
Item 1.
(1) A step of forming an uncured first colored coating film by applying an aqueous first colored paint (X) on an object containing a metal material and a plastic material;
(2) A step of coating the aqueous second colored paint (Y) on the uncured first colored coating film obtained in the step (1) to form an uncured second colored coating film,
(3) A step of coating the clear paint (Z) on the uncured second colored coating film obtained in the step (2) to form an uncured clear coating film, and (4) Steps (1) to (4) A step of simultaneously curing these three coating films by heating the uncured first colored coating film, the uncured second colored coating film and the uncured clear coating film formed in (3),
A multilayer coating film forming method for sequentially performing,
The aqueous first colored paint (X) is a non-chlorinated polyolefin resin (A), an acid value of 1 to 30 mg KOH / g, and an aqueous polyurethane having a time of 5 to 20 minutes for forming a film at a temperature of 20 ° C. Containing a resin (B), a blocked polyisocyanate compound (C) having a nonionic hydrophilic group, and a conductive pigment (D);
A multilayer coating film, wherein an average light transmittance at a wavelength of 360 to 420 nm of a cured coating film having a thickness of 5 μm obtained by applying and curing the aqueous first colored paint (X) is less than 1% Forming method.

  According to the method for forming a multilayer coating film of the present invention, excellent chipping resistance, adhesion, finish, weather resistance, and gasohol resistance can be applied to a metal member and a plastic member without using a primer. It becomes possible to form the coating film which has.

  Hereinafter, the multilayer coating film forming method of the present invention will be described in more detail.

  In this specification, the singular forms (a, an, the) include the singular and the plural unless specifically stated otherwise herein or otherwise clearly contradicted by context.

Process (1)
In the step (1) of the present invention, a water-based first colored paint (X) is applied onto an object to be coated containing a metal material and a plastic material. The aqueous first colored paint (X) is particularly applied to metal materials and plastic materials. Although it does not specifically limit as a to-be-coated object, For example, automobile outer plate parts, such as a passenger car, a truck, a motorcycle, a bus; Automobile parts, such as a bumper; Outer plates of household appliances, such as a mobile phone and an audio equipment And the like.

  Examples of the metal member include iron, aluminum, brass, copper, tinplate, stainless steel, galvanized steel, and zinc alloy (eg, Zn—Al, Zn—Ni, Zn—Fe, etc.) plated steel.

  The metal member may have a surface subjected to a surface treatment such as a phosphate treatment, a chromate treatment, or a complex oxide treatment, and an undercoat film is formed on the surface of the metal member. May be. Examples of the undercoat paint include electrodeposition paints, and among them, cationic electrodeposition paints are preferable.

  As a material of the plastic member, for example, a polyolefin obtained by (co) polymerizing one or more of olefins having 2 to 10 carbon atoms such as ethylene, propylene, butylene, and hexene is particularly preferable. In addition, polycarbonate, ABS resin, urethane resin, polyamide and the like are also included. Examples of these plastic members include automobile outer plate parts such as bumpers, spoilers, grills, and fenders; and outer plate parts of home appliances. Prior to the application of the aqueous first colored paint (X) of the present invention, these plastic members can be appropriately subjected to a degreasing treatment, a water washing treatment, and the like by a method known per se.

  The metal member and the plastic member can be assembled by a known method.

Water-based first colored paint (X)
Examples of the water-based first colored paint (X) to be coated on the article containing the metal material and the plastic material include non-chlorine polyolefin resin (A), specific water-based polyurethane resin (B), and nonionic hydrophilic It contains a block polyisocyanate compound (C) having a group and a conductive pigment (D).

  Moreover, the average light transmittance in wavelength 360-420nm of the cured coating film with a thickness of 5 micrometers obtained by apply | coating and hardening water-based 1st colored paint (X) is less than 1%.

Non-chlorine polyolefin resin (A)
The non-chlorine-based polyolefin resin (A) has a polyolefin molecule as a main skeleton, and a hydrophilic group such as a carboxyl group is introduced into the molecule, and is usually an unsaturated carboxylic acid or acid anhydride-modified polyolefin. (A) is preferred.

  The unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) can be usually obtained by graft copolymerizing an unsaturated carboxylic acid or acid anhydride with a polyolefin by a method known per se. The unsaturated carboxylic acid or acid anhydride that can be used for modification is a fatty acid having 3 to 10 carbon atoms that contains at least one, preferably one polymerizable double bond in one molecule and does not contain chlorine. Group carboxylic acids or anhydrides thereof are included, and specific examples include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, maleic anhydride and the like. Is preferred. The amount of graft copolymerization with the unsaturated carboxylic acid or its acid anhydride with respect to the polyolefin can be varied depending on the physical properties desired for the modified polyolefin, but generally 0.5% based on the solid content weight of the polyolefin. It is suitable to be in the range of -4 wt%, preferably 1-3 wt%, more preferably 1.2-2.8 wt%.

  On the other hand, the polyolefin subjected to modification is not chlorinated by, for example, (co) polymerizing one or more of olefins having 2 to 10 carbon atoms such as ethylene, propylene, butylene and hexene. Polyolefins are included, and those containing propylene as polymerized units are particularly preferred. The weight fraction of propylene units in the modified polyolefin is generally 0.5 to 1, particularly 0.7 to 0.99, more particularly 0, from the viewpoints of compatibility with other components and adhesion of the formed coating film. Those within the range of .8 to 0.99 are preferred.

  As the above-mentioned polyolefin, those known per se that are not chlorinated can be used without particular limitation, but from the point that the molecular weight distribution of the resulting polyolefin is narrow and excellent in random copolymerizability, etc. What is manufactured by (co) polymerizing an olefin using a single site catalyst as a polymerization catalyst is suitable. The single site catalyst is a polymerization catalyst having a uniform active site structure (single site), and a metallocene catalyst is particularly preferable among the single site catalysts. The metallocene-based catalyst is a metallocene (bis (cyclopentadidiene) which is a group 4-6 or group 8 transition metal compound or group 3 rare earth transition metal compound having at least one conjugated 5-membered ring ligand. It can be prepared by combining an enyl) metal complex and its derivatives) with an aluminoxane or boron-based co-catalyst for activating this, and an organoaluminum compound such as trimethylaluminum. The (co) polymerization of olefin can be carried out according to a method known per se, for example, by continuously adding alkylaluminum and metallocene catalyst while supplying olefin such as propylene and ethylene and hydrogen to the reaction vessel. .

  The unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) may be further acrylic-modified. Examples of the acrylic unsaturated monomer that can be used for the acrylic modification include those that do not contain chlorine, such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and butyl (meth) acrylate. C1-C20 alkyl esters of (meth) acrylic acid such as hexyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate C1-C21 hydroxyalkyl esters of (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, etc .; (meth) acrylic acid, glycidyl (meth) acrylate, Its (meth) acrylamide, (meth) acrylonitrile, etc. An acrylic monomer or more styrene can be mentioned, these can be used alone or in combination.

  In the present specification, “(meth) acryl” means “acryl or methacryl”, and “(meth) acrylate” means “acrylate or methacrylate”.

  The acrylic modification of the polyolefin is, for example, an acrylic unsaturated monomer that does not contain chlorine and has reactivity with the carboxyl group in the unsaturated carboxylic acid or anhydride modified polyolefin produced as described above. For example, a polymerizable unsaturated group is introduced into a polyolefin by reacting glycidyl (meth) acrylate and the like, and then the above-mentioned acrylic unsaturated monomer is used alone or in combination of two or more kinds in the polyolefin into which the polymerizable unsaturated group is introduced. It can be carried out by combining (co) polymerization. The amount of the acrylic unsaturated monomer used in the acrylic modification of the polyolefin can be changed depending on the properties desired for the modified polyolefin, but from the viewpoint of compatibility with other components and adhesion of the formed coating film. In general, 30 wt% or less, particularly 0.1 to 20 wt%, more particularly 0.15 to 15 wt%, based on the solid content weight of the unsaturated carboxylic acid or acid anhydride modified polyolefin (a) obtained It is desirable to be within the range.

  The unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) may be further modified with a compound having a polyoxyalkylene chain. Examples of the polyoxyalkylene chain in the compound having a polyoxyalkylene chain include a polyoxyethylene chain, a polyoxypropylene chain, a block chain of polyoxyethylene and polyoxypropylene, and the like.

  The compound having a polyoxyalkylene chain usually has a number average molecular weight within the range of 400 to 3,000, preferably 500 to 2,000. If the number average molecular weight is less than 400, the effect as a hydrophilic group cannot be sufficiently exerted, and the water resistance may be adversely affected. On the other hand, if the number average molecular weight is more than 3,000, it is solidified at room temperature and is soluble. May worsen and become difficult to handle.

  The unsaturated carboxylic acid or anhydride-modified polyolefin (a) has a melting point from the viewpoints of compatibility with other components, adhesion of the formed coating film to the plastic member and interlayer adhesion to the top coating layer. Is in the range of 120 ° C. or less, preferably 60 to 110 ° C., more preferably 70 to 100 ° C., and the weight average molecular weight (Mw) is 10,000 to 230,000, preferably 50,000 to 200,000. More preferably, it is desirable to be within the range of 60,000 to 150,000.

  In addition, the unsaturated carboxylic acid or anhydride-modified polyolefin (a) generally has a heat of fusion of 1 to 50 mJ from the viewpoint of adhesion of the formed coating film to the plastic member and interlayer adhesion with the top coat layer. / Mg, particularly in the range of 2 to 50 mJ / mg.

  Here, the melting point and heat of fusion of the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) were 20 mg of modified polyolefin using a scanning scanning calorimeter “DSC-5200” (trade name, manufactured by Seiko Denshi Kogyo Co., Ltd.). The amount of heat was measured from −100 ° C. to 150 ° C. at a heating rate of 10 ° C./min. The melting point of the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) can be adjusted by changing the monomer composition of the polyolefin, particularly the amount of the α-olefin monomer. If it is difficult to determine the heat of fusion, first heat the sample to 120 ° C, cool it to room temperature at 10 ° C / min, leave it for 2 days, and measure the heat by the above method. Can do.

  The weight average molecular weight of the unsaturated carboxylic acid or acid anhydride modified polyolefin (a) is a value obtained by converting the weight average molecular weight measured by gel permeation chromatography based on the weight average molecular weight of polystyrene. The measurement was performed at a column temperature of 135 ° C. and a flow rate of 1.0 ml / min using “HLC / GPC150C” (Waters, 60 cm × 1) as a permeation chromatography apparatus and o-dichlorobenzene as a solvent. The injection sample was prepared by dissolving at a temperature of 140 ° C. for 1 to 3 hours so as to obtain a solution concentration of 5 mg of polyolefin in 3.4 ml of o-dichlorobenzene. As a column for gel permeation chromatography, “GMHHR-H (S) HT” (manufactured by Tosoh Corporation, trade name) can be used.

  Furthermore, the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) is generally a ratio of the weight average molecular weight to the number average molecular weight (from the viewpoint of compatibility with other components and adhesion of the formed coating film). Mw / Mn) is desirably in the range of 1.5 to 7.0, preferably 1.8 to 6.0, and more preferably 2.0 to 4.0.

  The non-chlorine polyolefin resin (A) can be dispersed in water by dispersing the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) described above in an aqueous medium. A part or all of the carboxyl groups in the carboxylic acid or acid anhydride-modified polyolefin (a) can be neutralized with an amine compound and / or dispersed in water with an emulsifier. From the viewpoint of improving water dispersibility, it is desirable to use neutralization and water dispersion with an emulsifier in combination.

  Examples of amine compounds used for neutralization include tertiary amines such as triethylamine, tributylamine, dimethylethanolamine and triethanolamine; secondary amines such as diethylamine, dibutylamine, diethanolamine and morpholine; propylamine and ethanolamine Examples include primary amines. When using these amine compounds, the amount used is usually within the range of 0.1 to 1.0 molar equivalents relative to the carboxyl group in the unsaturated carboxylic acid or anhydride modified polyolefin (a). Is preferred.

  Examples of the emulsifier include polyoxyethylene monooleyl ether, polyoxyethylene monostearyl ether, polyoxyethylene monolauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene Nonions such as ethylene octyl phenyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate Emulsifiers; anio such as sodium and ammonium salts such as alkyl sulfonic acid, alkyl benzene sulfonic acid and alkyl phosphoric acid A polyoxyalkylene group-containing anionic emulsifier having an anionic group and a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group in one molecule, or the anion in one molecule. A reactive anionic emulsifier having a reactive group and a polymerizable unsaturated group can also be used. These emulsifiers can be used alone or in combination of two or more.

  Said emulsifier can be normally used in 1-20 weight part with respect to 100 weight part of solid content of the said unsaturated carboxylic acid or acid anhydride modified polyolefin (a).

  The emulsification method of the unsaturated carboxylic acid or acid anhydride-modified polyolefin (a) is not particularly limited, and known methods such as phase inversion emulsification, D phase emulsification, forced emulsification, gel emulsification, self-emulsification, inversion emulsification, and high pressure emulsification. The method can be adopted. Of these, the self-emulsification method is preferred from the viewpoint of the appearance and water resistance of the resulting coating film.

  Moreover, the aqueous dispersion of the unsaturated carboxylic acid or acid anhydride modified polyolefin (a) obtained as described above is prepared in the presence of the water-dispersed unsaturated carboxylic acid or acid anhydride modified polyolefin (a). By emulsion polymerization of acrylic unsaturated monomers as listed in the description of acrylic modification, a non-chlorinated polyolefin resin (A) further containing an acrylic-modified unsaturated carboxylic acid or acid anhydride-modified polyolefin is obtained. You can also

  The content of the non-chlorine polyolefin resin (A) is 10 to 60% by mass, preferably 20 to 50% by mass, more preferably, based on the total resin solid mass in the aqueous first colored paint (X). It is suitable that it is 25-50 mass% from the point of the chipping resistance of the coating film obtained, adhesiveness, finishing property, weather resistance, and gasohol resistance.

Aqueous polyurethane resin (B)
The water-based polyurethane resin (B) means a polyurethane resin that can be dispersed in an aqueous medium containing water as a main solvent or dispersion medium. The form in the aqueous medium includes a water-soluble type, a colloidal dispersion type, and an emulsion. Either a type or a slurry type may be used, but a colloidal dispersion type or an emulsion type is desirable.

  As the aqueous polyurethane resin (B), those known per se can be used. For example, a polyol such as polyester polyol, polycarbonate polyol or polyether polyol, or a low molecular weight hydroxyl group-containing compound and polyisocyanate are reacted. Preferred are those obtained by chain extension in the presence of a chain extender, which is a low molecular weight compound having at least two active hydrogens in one molecule, such as diol and diamine. It can be used by stably dispersing or dissolving in an aqueous medium.

  As the polyol component, polyester polyols and polyether polyols are particularly preferable from the viewpoint of chipping resistance, adhesion, finish, weather resistance, and gasohol resistance of the resulting coating film.

  Examples of the polyester polyol used for the production of the aqueous polyurethane resin (B) include aliphatic diols such as 1,4-butanediol and 1,6-hexanediol, and aliphatic dicarboxylics such as adipic acid and sebacic acid. Polyester polyols obtained by reacting with acids; polyester polyols obtained by reacting the aliphatic diols with aromatic dicarboxylic acids such as terephthalic acid and the like. Polycarbonate polyols include, for example, 1,6 -Polycarbonate polyols obtained by reacting diols such as hexanediol and 3-methyl-1,5-pentanediol with carbonates such as dimethyl carbonate, and the like. Ji glycol, such as polypropylene glycol and polytetramethylene glycol, ethylene oxide, such as polyalkylene glycols obtained by ring-opening polymerization of propylene oxide. Examples of the polyisocyanate include aliphatic and alicyclic diisocyanates such as hexamethylene diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, and hydrogenated xylylene diisocyanate, and isocyanurate cycloadducts thereof. As the polyisocyanate component, isophorone diisocyanate is particularly preferable from the viewpoint of chipping resistance, adhesion, finish, weather resistance, and gasohol resistance of the resulting coating film.

  Furthermore, examples of the diol as the chain extender include ethylene glycol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, cyclohexanediol, and the like. Examples thereof include ethylenediamine, propylenediamine, xylylenediamine and the like.

As a method of stably dispersing or dissolving the aqueous polyurethane resin (B) in water, for example, the following method can be used.
(1) By using a carboxyl group-containing diol such as dimethylolpropionic acid or dimethylolbutanoic acid as a polyurethane raw material, a carboxyl group is introduced into the polyurethane, and a part or all of the carboxyl group is neutralized. A method of imparting hydrophilicity to polyurethane by the method and dispersing or dissolving in water by self-emulsification.
(2) A method of producing a water-soluble polyurethane using a hydrophilic polyol such as polyethylene glycol as a polyol which is a raw material for producing polyurethane and dispersing or dissolving it in water.
(3) Non-reactive and / or cationic emulsifiers and mechanical shearing force are used for polyurethanes that have completed the reaction or polyurethanes whose terminal isocyanate groups are blocked with blocking agents such as oxime, alcohol, phenol, mercaptan, amine, sodium bisulfite, etc. To forcibly disperse in water.
(4) A method in which a urethane prepolymer having a terminal isocyanate group is mixed with water / emulsifier / chain extender, and dispersion and high molecular weight are simultaneously performed using mechanical shearing force.

  The aqueous polyurethane resin (B) is not limited to those obtained by a single production method, and a mixture of polyurethanes obtained by the respective methods can also be used.

  The water-based polyurethane resin (B) has an acid value of 1 to 30 mgKOH / g, preferably 3 to 25 mgKOH / g, in terms of chipping resistance, adhesion, finish, weather resistance and gasohol resistance of the resulting coating film. More preferably, it exists in the range of 5-20 mgKOH / g.

  The water-based polyurethane resin (B) has a time required to form a film at a temperature of 20 ° C. for 5 to 20 minutes from the viewpoint of chipping resistance, adhesion, finish, weather resistance and gasohol resistance of the resulting coating film, Preferably it is 10-20 minutes, More preferably, it is 12-18 minutes.

  Here, the time until film formation refers to the time required for the aqueous polyurethane resin to form a continuous film. The time until the water-based polyurethane resin is formed is measured as follows.

  An aqueous polyurethane resin solution adjusted to have a solid content of 28% under an atmosphere of room temperature of 20 ° C. and humidity of 60% was applied onto a PET film using a bar coater so that the wet film thickness was 40 μm. Immediately after coating, 0.3 mL of ion-exchanged water is dropped from a height of 1 cm above the coating film using a dropper every 1 hour, and the change in the diameter of the water droplet in 1 second immediately after dropping is 1 mm or less. The time from the start point to the end point when the end point is taken as the end point is defined as “time until the aqueous polyurethane resin is formed”.

  The aqueous polyurethane resin (B) has an average particle diameter in an aqueous medium of 70 to 250 nm, preferably 80 to 230 nm, more preferably 100 to 200 nm. From the viewpoint of resistance, weather resistance and gasohol resistance.

  In this specification, an average particle diameter is the value measured at 20 degreeC, after diluting with deionized water by a conventional method using the dynamic light-scattering particle diameter distribution measuring apparatus. As the dynamic light scattering particle size distribution measuring apparatus, for example, “Submicron Particle Analyzer N5” (trade name, manufactured by Beckman Coulter, Inc.) can be used.

  In the aqueous first colored paint (X), the content of the aqueous polyurethane resin (B) is 10 to 50% by mass, preferably 10 to 40%, based on the total amount of resin solids in the aqueous first colored paint (X). From the viewpoint of chipping resistance, adhesion, finish, weather resistance, and gasohol resistance of the resulting coating film, it is preferable that the content is 15% by mass, more preferably 15-30% by mass.

Block polyisocyanate compound having nonionic hydrophilic group (C)
In the block polyisocyanate compound (C) having a nonionic hydrophilic group, a part of the isocyanate group of the polyisocyanate compound having two or more isocyanate groups in one molecule is modified with a nonionic hydrophilic group, and the remaining part or It is a compound in which all isocyanate groups are blocked with a blocking agent.

  The block polyisocyanate compound (C) having a nonionic hydrophilic group can be obtained by a known method. For example, by reacting an isocyanate group in a polyisocyanate compound (c1) having two or more isocyanate groups in one molecule with an active hydrogen-containing compound (c2) having a nonionic hydrophilic group and a blocking agent (c3). A block polyisocyanate compound having a nonionic hydrophilic group can be obtained (hereinafter, the block polyisocyanate compound having a nonionic hydrophilic group thus obtained is referred to as “(C1)”).

  When the isocyanate group in the polyisocyanate compound (c1) is reacted with the active hydrogen-containing compound (c2) having a nonionic hydrophilic group and the blocking agent (c3), the polyisocyanate compound (c1) and the hydrophilic group are reacted. The order of reaction of the active hydrogen-containing compound (c2) and the blocking agent (c3) is not particularly limited. Specifically, after reacting the active hydrogen-containing compound (c2) having a hydrophilic group with a part of the isocyanate groups in the polyisocyanate compound (c1), the remaining isocyanate groups are blocked with the blocking agent (c3). , A method in which a part of the isocyanate group in the polyisocyanate compound (c1) is blocked with a blocking agent (c3), and then the remaining isocyanate group is reacted with an active hydrogen-containing compound (c2) having a hydrophilic group, and a polyisocyanate compound ( Examples thereof include a method of reacting an active hydrogen-containing compound (c2) having a hydrophilic group with an isocyanate group in c1) and a blocking agent (c3) at the same time.

Polyisocyanate compound (c1)
The polyisocyanate compound (c1) is a compound having at least two isocyanate groups in one molecule, and includes, for example, an aliphatic polyisocyanate, an alicyclic polyisocyanate, an araliphatic polyisocyanate, an aromatic polyisocyanate, And polyisocyanate derivatives.

  Examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3. -Aliphatic diisocyanates such as butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate (common name: lysine diisocyanate); 2 , 6-Diisocyanatohexanoic acid 2-isocyanatoethyl, 1,6-diisocyanato-3-isocyanatomethylhexane, 1,4,8-triisocyanatooctane, 1,6,6 1-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 1,3,6-triisocyanatohexane, 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyl Examples thereof include aliphatic triisocyanates such as octane.

  Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name) : Isophorone diisocyanate), 4-methyl-1,3-cyclohexylene diisocyanate (common name: hydrogenated TDI), 2-methyl-1,3-cyclohexylene diisocyanate, 1,3- or 1,4-bis (isocyanato) Methyl) cyclohexane (common name: hydrogenated xylylene diisocyanate) or a mixture thereof, methylenebis (4,1-cyclohexanediyl) diisocyanate (common name: hydrogenated MDI), alicyclic diisocyanate such as norbornane diisocyanate 1,3,5-triisocyanatocyclohexane, 1,3,5-trimethylisocyanatocyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2 .1) Heptane, 2- (3-isocyanatopropyl) -2,6-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 3- (3-isocyanatopropyl) -2,5- Di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) ) Heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanate) Toethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) -heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3 An alicyclic triisocyanate such as -isocyanatopropyl) -bicyclo (2.2.1) heptane can be used.

  Examples of the araliphatic polyisocyanate include methylene bis (4,1-phenylene) diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω′-diisocyanato- Aromatic aliphatic diisocyanates such as 1,4-diethylbenzene, 1,3- or 1,4-bis (1-isocyanato-1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof; 1,3 And araliphatic triisocyanates such as 5-triisocyanatomethylbenzene.

  Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (common name: 2,4- TDI), 2,6-tolylene diisocyanate (common name: 2,6-TDI) or mixtures thereof, aromatic diisocyanates such as 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate; triphenylmethane-4 , 4 ′, 4 ″ -triisocyanate, 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene and the like; 4,4′-diphenylmethane-2,2 ′ , 5,5'-Tetraisocyanate And aromatic tetraisocyanates such as equal.

  Examples of the polyisocyanate derivatives include dimer, trimer, biuret, allophanate, uretdione, uretoimine, isocyanurate, oxadiazine trione, polymethylene polyphenyl polyisocyanate (crude MDI, polymeric MDI). And Crude TDI.

  The above polyisocyanates and derivatives thereof may be used alone or in combination of two or more. Of these polyisocyanates, the polyisocyanate compound (c1) is an aliphatic diisocyanate, since the resulting block polyisocyanate compound (C1) having a nonionic hydrophilic group is less likely to yellow when heated. Alicyclic diisocyanates and their derivatives are preferred. Of these, aliphatic diisocyanates and derivatives thereof are more preferable from the viewpoint of improving the flexibility of the formed coating film.

  Moreover, as said polyisocyanate compound (c1), you may use the prepolymer formed by making the said polyisocyanate and its derivative (s), and the compound which can react with this polyisocyanate react on an isocyanate group excess condition. Examples of the compound capable of reacting with the polyisocyanate include compounds having an active hydrogen group such as a hydroxyl group and an amino group. Specifically, for example, polyhydric alcohol, low molecular weight polyester resin, amine, water, etc. Can be used.

  The polyisocyanate compound (c1) is a polymer of an isocyanate group-containing polymerizable unsaturated monomer, or a polymerizable unsaturated monomer other than the isocyanate group-containing polymerizable unsaturated monomer and the isocyanate group-containing polymerizable unsaturated monomer. A copolymer with a monomer may be used.

  The polyisocyanate compound (c1) is obtained from the viewpoint of the reactivity of the obtained block polyisocyanate compound (C1) having a nonionic hydrophilic group and the compatibility between the composition containing the block polyisocyanate compound and other coating components. The number average molecular weight is preferably in the range of 300 to 20,000, more preferably in the range of 400 to 8,000, and still more preferably in the range of 500 to 2,000.

  The polyisocyanate compound (c1) is obtained by reacting the obtained block polyisocyanate compound (C1) having a nonionic hydrophilic group and the block polyisocyanate compound (C1) having the nonionic hydrophilic group, and other coating components. From the viewpoint of compatibility, it is preferable that the average number of isocyanate functional groups in one molecule is in the range of 2 to 100. As a minimum, 3 is more preferable from a viewpoint of improving the reactivity of the block polyisocyanate compound (C1) which has a nonionic hydrophilic group obtained. As an upper limit, 20 is more preferable from a viewpoint of preventing gelation at the time of manufacture of the block polyisocyanate compound (C1) which has a nonionic hydrophilic group.

Active hydrogen-containing compound having nonionic hydrophilic group (c2)
As the active hydrogen-containing compound having a nonionic hydrophilic group, for example, an active hydrogen-containing compound having a polyoxyalkylene group can be suitably used. As said polyoxyalkylene group, a polyoxyethylene group, a polyoxypropylene group, a polyoxyethylene (oxypropylene) group etc. are mentioned, for example, These can be used individually or in combination of 2 or more types. Especially, the active hydrogen containing compound which has a polyoxyethylene group from a viewpoint of the storage stability of the block polyisocyanate compound (C1) which has a nonionic hydrophilic group obtained is preferable.

  The active hydrogen-containing compound having a polyoxyethylene group is 3 or more from the viewpoint of storage stability of the resulting block polyisocyanate compound (C1) having a nonionic hydrophilic group and water resistance of the formed coating film, etc. Preferably it has 5 to 100, more preferably 8 to 45 continuous oxyethylene groups.

  Moreover, the active hydrogen containing compound which has the said polyoxyethylene group may contain oxyalkylene groups other than an oxyethylene group other than the continuous oxyethylene group. Examples of the oxyalkylene group other than the oxyethylene group include an oxypropylene group, an oxybutylene group, and an oxystyrene group. The molar ratio of the oxyethylene group in the oxyalkylene group in the active hydrogen-containing compound having a polyoxyethylene group is 20 to 100 from the viewpoint of storage stability after water dispersion of the resulting block polyisocyanate compound-containing composition. It is preferably in the range of mol%, and preferably in the range of 50 to 100 mol%. When the molar ratio of the oxyethylene group in the oxyalkylene group is less than 20 mol%, hydrophilicity is not sufficient, and the storage stability of the resulting block polyisocyanate compound (C1) having a nonionic hydrophilic group is lowered. There is a case.

  The active hydrogen-containing compound having a nonionic hydrophilic group is a number average molecular weight from the viewpoint of storage stability of the resulting block polyisocyanate compound (C1) having a nonionic hydrophilic group and water resistance of the formed coating film. Is preferably in the range of 200 to 2,000. As a minimum of a number average molecular weight, 300 is more preferable from a viewpoint of the storage stability of the block polyisocyanate compound (C1) which has a nonionic hydrophilic group obtained, and 400 is still more preferable. As an upper limit, 1,500 is more preferable from the viewpoint of water resistance of the coating film formed by the water-based first colored paint (X) of the present invention, and 1,200 is more preferable.

  Examples of the active hydrogen-containing compound having a nonionic hydrophilic group include polyethylene glycol monoalkyl ethers (also known as ω-alkoxypolyoxyethylene) such as polyethylene glycol monomethyl ether and polyethylene glycol monoethyl ether, polypropylene glycol monomethyl ether, and polypropylene. Polypropylene glycol monoalkyl ethers such as glycol monoethyl ether (also known as ω-alkoxypolyoxypropylene), ω-alkoxypolyoxyethylene (oxypropylene), ω-alkoxypolyoxyethylene (oxypropylene), etc. Ethylene (oxypropylene), polyethylene glycol (propylene glycol) monomethyl ether, polyethylene glycol Polyethylene glycol (propylene glycol) monoalkyl ether such as (propylene glycol) monoethyl ether, polyethylene glycol, polypropylene glycol, polyethylene glycol (propylene glycol), α- (aminoalkyl) -ω-alkoxypolyoxyethylene, α- (amino Alkyl) -ω-alkoxypolyoxypropylene, α- (aminoalkyl) -ω-alkoxypolyoxyethylene (oxypropylene) and the like, and these can be used alone or in combination of two or more. Of these, polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether and polyethylene glycol are preferable, and polyethylene glycol monomethyl ether is more preferable.

  In the present specification, “polyethylene glycol (propylene glycol)” means a copolymer of ethylene glycol and propylene glycol, and includes both a block copolymer and a random copolymer.

  Moreover, as a commercial item of the said polyethyleneglycol monomethyl ether, for example, "UNIOX M-400", "UNIOX M-550", "UNIOX M-1000", "UNIOX M-" made by NOF CORPORATION 2000 "and the like. Examples of the commercially available polyethylene glycol include “PEG # 200”, “PEG # 300”, “PEG # 400”, “PEG # 600”, “PEG # 1000”, “ PEG # 1500 "," PEG # 1540 "," PEG # 2000 "and the like.

  When reacting a part of the isocyanate groups in the polyisocyanate compound (c1) with the active hydrogen-containing compound (c2) having the nonionic hydrophilic group, the resulting block polyisocyanate compound (C1) having a nonionic hydrophilic group is obtained. Polyisocyanate compound (c1) and nonion from the viewpoints of storage stability and curability and adhesion, smoothness, sharpness and water resistance of the coating film formed by the aqueous first colored paint (X) of the present invention The reaction ratio with the active hydrogen-containing compound (c2) having a hydrophilic hydrophilic group is such that the number of moles of active hydrogen in the active hydrogen-containing compound is 0.03 to 1 mol based on 1 mole of the isocyanate group in the polyisocyanate compound (c1). It is preferably within the range of 0.6 mole. As an upper limit, from a viewpoint of the water resistance of the coating film formed by the sclerosis | hardenability of the block polyisocyanate compound (C1) which has a nonionic hydrophilic group obtained, and the water-based 1st colored coating material (X) of this invention, it is 0.4. Is more preferable, and 0.3 is even more preferable. As the lower limit, the storage stability of the resulting block polyisocyanate compound (C1) having a nonionic hydrophilic group and the adhesion, smoothness, and sharpness of the coating film formed by the aqueous first colored paint (X) of the present invention From the viewpoints of properties and water resistance, 0.04 is more preferable, and 0.05 is more preferable.

Blocking agent (c3)
Examples of the blocking agent include phenolic, alcoholic, active methylene, mercaptan, acid amide, acid imide, imidazole, urea, oxime, carbamic acid, amine, imine, etc. These can be used alone or in combination of two or more. More specific blocking agents are shown below.
(1) phenolic; phenol, cresol, ethylphenol, butylphenol, etc.
(2) Alcohol type; ethylene glycol, benzyl alcohol, methanol, ethanol, etc.
(3) Active methylene type; malonic acid diester, acetoacetic acid ester, isobutyrylacetic acid ester, etc.
(4) mercaptan series; butyl mercaptan, dodecyl mercaptan, etc. (5) acid amide series; acetanilide, acetic acid amide, ε-caprolactam, δ-valerolactam, γ-butyrolactam, etc.
(6) Acid imide type: succinimide, maleic imide, etc.
(7) Imidazole series; imidazole, 2-methylimidazole, etc.
(8) Urea system; urea, thiourea, ethylene urea, etc.
(9) Oxime series: formaldoxime, acetoaldoxime, methyl ethyl ketoxime, cyclohexanone oxime, etc.
(10) Carbamate system; phenyl N-phenylcarbamate, etc.
(11) Amine type; diphenylamine, aniline, carbazole, etc.
(12) Imine type; ethyleneimine, polyethyleneimine and the like.

  In the blocking reaction of the isocyanate group with the blocking agent (c3), a reaction catalyst can be optionally used. Examples of the reaction catalyst include metal hydroxide, metal alkoxide, metal carboxylate, metal acetyl acetylate, hydroxide of onium salt, onium carboxylate, metal salt of active methylene compound, onium salt of active methylene compound, aminosilanes Basic compounds such as amines and phosphines are preferred. Of these, ammonium salts, phosphonium salts, and sulfonium salts are preferred as onium salts. The amount of the reaction catalyst used is usually preferably within the range of 10 to 10,000 ppm, based on the total solid mass of the polyisocyanate compound (c1) and the blocking agent (c3), and preferably 20 to 5,000 ppm. More preferably, it is in the range.

  The blocking reaction of the isocyanate group with the blocking agent (c3) can be performed at 0 to 150 ° C., and a solvent may be used. In this case, the solvent is preferably an aprotic solvent, and particularly preferably an ester, ether, N-alkylamide, ketone or the like. If the reaction proceeds as intended, an acid component may be added to neutralize the basic compound as a catalyst and stop the reaction.

  In the blocking reaction of the isocyanate group with the blocking agent (c3), the amount of the blocking agent (c3) used is not particularly limited, but is 0.1 to 3 with respect to 1 mol of the isocyanate group in the polyisocyanate compound (c1). It is suitable to use a mole, preferably 0.2 to 2 mole. Moreover, the blocking agent which did not react with the isocyanate group in the polyisocyanate compound (c1) can be removed after completion of the blocking reaction.

  Especially, it is preferable that a blocking agent (c3) is an active methylene type | system | group from a viewpoint of the low-temperature curability of the coating film formed with the water-based 1st colored coating material (X) of this invention.

  As a particularly preferable form of the block polyisocyanate compound (C1) having a nonionic hydrophilic group from the viewpoint of the stability of the aqueous first colored paint (X) of the present invention, the following general formula (IV)

[In Formula (IV), R ¹ independently represents a hydrocarbon group having 1 to 12 carbon atoms, and may be the same or different from each other. ]
And a blocked polyisocyanate compound (C1-1) having a nonionic hydrophilic group having a blocked isocyanate group represented by formula (V):

Wherein (V), ^{R 6} and ^{R 7} independently represent a hydrocarbon group having 1 to 12 carbon atoms. ]
And a blocked polyisocyanate compound (C1-2) having a nonionic hydrophilic group having a blocked isocyanate group represented by

Block polyisocyanate compound having nonionic hydrophilic group (C1-1)
The block polyisocyanate compound (C1-1) having a nonionic hydrophilic group is a block polyisocyanate compound having a block isocyanate group represented by the general formula (IV).

Among them, as the blocking agent is one of the raw material of the block polyisocyanate compound (c3), a point that may be used relatively easily manufactured can active methylene blocking agent compound of, R ¹ is 1 to the number of carbon atoms 3 alkyl groups are preferred. Among these, from the viewpoint of improving the compatibility between the obtained nonionic hydrophilic group-containing blocked polyisocyanate compound (C1) and other coating components, R ¹ is preferably an alkyl group having 2 or 3 carbon atoms. From the viewpoint of the storage stability of the block polyisocyanate compound (C1) having a nonionic hydrophilic group and the smoothness and sharpness of the coating film formed by the aqueous first colored paint (X) of the present invention, R ¹ is More preferably, it is an isopropyl group.

  The block polyisocyanate compound (C1-1) having a nonionic hydrophilic group is, for example, carbon as the polyisocyanate compound (c1) and the active hydrogen-containing compound (c2) having a nonionic hydrophilic group, and the blocking agent (c3). It can be obtained by reacting with a dialkyl malonate having a hydrocarbon group of 1 to 12.

  Examples of the dialkyl malonate include dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, diisobutyl malonate, disec-butyl malonate, and di-t malonate. -Butyl, di-n-pentyl malonate, di-n-hexyl malonate, di (2-ethylhexyl) malonate and the like can be mentioned, and these can be used alone or in combination of two or more. Of these, dimethyl malonate, diethyl malonate, di-n-propyl malonate, diisopropyl malonate, di-n-butyl malonate, diisobutyl malonate, di-sec-butyl malonate, and di-t-butyl malonate are preferred. Diethyl acid, di-n-propyl malonate, and diisopropyl malonate are more preferable, and diisopropyl malonate is more preferable.

Block polyisocyanate compound having nonionic hydrophilic group (C1-2)
The block polyisocyanate compound (C1-2) having a nonionic hydrophilic group is a block polyisocyanate compound having a block isocyanate group represented by the general formula (V).

Among these, as the blocking agent (c3), which is one of the raw materials of the blocked polyisocyanate compound, an active methylene-based blocking agent compound that can be produced relatively easily can be used, so that R ⁶ and R ⁷ are carbon. It is preferable that it is a C1-C3 alkyl group. Among these, from the viewpoint of improving the compatibility between the resulting nonionic hydrophilic group-containing blocked polyisocyanate compound (C1) and other coating components, R ⁶ and R ⁷ may be an alkyl group having 2 or 3 carbon atoms. Preferably, from the viewpoint of storage stability of the obtained block polyisocyanate compound (C1) having a nonionic hydrophilic group, smoothness of a coating film formed by the aqueous first colored paint (X) of the present invention, and sharpness, More preferably, R ⁶ and R ⁷ are isopropyl groups.

  The block polyisocyanate compound (C1-2) having a nonionic hydrophilic group is, for example, carbon as the polyisocyanate compound (c1) and the active hydrogen-containing compound (c2) having a nonionic hydrophilic group, and the blocking agent (c3). It can be obtained by reacting an acetoacetic acid ester having a hydrocarbon group of 1 to 12 or an isobutyryl acetate ester having a hydrocarbon group of 1 to 12 carbon atoms. Especially, it is preferable to make it react using the isobutyryl acetate ester which has a C1-C12 hydrocarbon group as a blocking agent (c3).

  Examples of the isobutyryl acetate include, for example, methyl isobutyryl acetate, ethyl isobutyryl acetate, n-propyl isobutyryl acetate, isopropyl isobutyryl acetate, n-butyl isobutylyl acetate, isobutyl isobutylyl acetate, sec-butyl isobutyryl acetate, t-butyl isobutyryl acetate, isobutyryl Examples include n-pentyl acetate, n-hexyl isobutyryl acetate, 2-ethylhexyl isobutyryl acetate, phenyl isobutyryl acetate, benzyl isobutyryl acetate and the like, and these can be used alone or in combination of two or more. Of these, methyl isobutyryl acetate, ethyl isobutyryl acetate and isopropyl isobutyryl acetate are preferred.

  Examples of the acetoacetate include, for example, methyl acetoacetate, ethyl acetoacetate, n-propyl acetoacetate, isopropyl acetoacetate, n-butyl acetoacetate, isobutyl acetoacetate, sec-butyl acetoacetate, t-butyl acetoacetate, acetoacetate Examples include n-pentyl acetate, n-hexyl acetoacetate, 2-ethylhexyl acetoacetate, phenyl acetoacetate, benzyl acetoacetate and the like, and these can be used alone or in combination of two or more. Of these, methyl acetoacetate, ethyl acetoacetate and isopropyl acetoacetate are preferred.

In the present invention, particularly from the viewpoint of stability in water, the block polyisocyanate compound (C1) having a nonionic hydrophilic group is further added to the block polyisocyanate compound (C1) having a nonionic hydrophilic group, and a secondary alcohol (c4). A block polyisocyanate compound having a nonionic hydrophilic group obtained by reacting (hereinafter, the block polyisocyanate compound having a nonionic hydrophilic group thus obtained is referred to as “(C2)”). Is preferred.
Block polyisocyanate compound having nonionic hydrophilic group (C2)
The block polyisocyanate compound (C2) having a nonionic hydrophilic group includes, for example, the block polyisocyanate compound (C1) having a nonionic hydrophilic group and a secondary alcohol (c4) represented by the following general formula (VI):

[In Formula (VI), R ² , R ⁴ and R ⁵ independently represent a hydrocarbon group having 1 to 12 carbon atoms, and R ³ represents a linear or branched group having 1 to 12 carbon atoms. Represents an alkylene group. ]
Can be obtained by reacting.

Secondary alcohol (c4)
The secondary alcohol (c4) is a compound represented by the general formula (VI). Among them, from the viewpoint of enhancing the reactivity with the blocked polyisocyanate compound having a nonionic hydrophilic group (C1) and the secondary alcohol (c4), R ² is preferably a methyl group. Further, when R ³ , R ⁴ and R ⁵ each have a large number of carbon atoms, the polarity of the resulting block polyisocyanate compound (C2) having a nonionic hydrophilic group is lowered, and the compatibility with other paint components is lowered. R ³ is preferably an alkylene group having 1 to ³ carbon atoms, and R ⁴ and R ⁵ are preferably methyl groups.

  Examples of the secondary alcohol (c4) include 4-methyl-2-pentanol, 5-methyl-2-hexanol, 6-methyl-2-heptanol, 7-methyl-2-octanol, and the like. Can be used alone or in combination of two or more. Among them, after the reaction of the block polyisocyanate compound (C1) having a nonionic hydrophilic group and the secondary alcohol (c4), when a part or all of the unreacted secondary alcohol (c4) is distilled off, Since removal of the secondary alcohol (c4) is relatively easy, 4-methyl-2-pentanol having a relatively low boiling point is more preferable.

  The blocked polyisocyanate compound (C2) having a nonionic hydrophilic group is particularly preferably in the form of the following compounds (C2-1) and (C2-2) from the viewpoint of the stability of the aqueous first colored paint (X) of the present invention. Can be mentioned.

Block polyisocyanate compound having nonionic hydrophilic group (C2-1)
Specifically, the block polyisocyanate compound (C2-1) having a nonionic hydrophilic group is, for example, the following general formula (IV) described in the description of the block polyisocyanate compound (C1) having a nonionic hydrophilic group.

[In Formula (IV), R ¹ independently represents a hydrocarbon group having 1 to 12 carbon atoms, and may be the same or different. ]
It can obtain by making the block polyisocyanate compound (C1-1) which has the block isocyanate group shown by and which has a nonionic hydrophilic group react with the said secondary alcohol (c4).

In this case, at least one of R ¹ in the blocked isocyanate group in the blocked polyisocyanate compound (C1-1) having the nonionic hydrophilic group is represented by the following general formula (VII).

[In Formula (VII), R ² , R ⁴ and R ⁵ independently represent a hydrocarbon group having 1 to 12 carbon atoms, and R ³ represents a linear or branched group having 1 to 12 carbon atoms. Represents an alkylene group. ]
It is substituted with a group represented by

  In this case, the obtained blocked polyisocyanate compound is a blocked isocyanate group represented by the following general formula (I):

[In the formula (I), R ¹ , R ² , R ⁴ and R ⁵ independently represent a hydrocarbon group having 1 to 12 carbon atoms, and R ³ is a straight chain having 1 to 12 carbon atoms or Represents a branched alkylene group. ]
Or a blocked isocyanate group represented by the following general formula (II)

[In formula (II), R ² , R ³ , R ⁴ and R ⁵ are the same as above. ]
Have

The reaction of the block polyisocyanate compound (C1-1) having a nonionic hydrophilic group and the secondary alcohol (c4) is, for example, in the block isocyanate group in the block polyisocyanate compound (C1-1) having a nonionic hydrophilic group. The method is not particularly limited as long as at least one of R ¹ can be substituted with the group represented by the general formula (VII). In particular, a part or all of the alcohol derived from at least one of R ^{1 in} the block polyisocyanate compound (C1-1) having a nonionic hydrophilic group is distilled out of the system by heating, reduced pressure, etc. A method of promoting and obtaining a blocked polyisocyanate compound having a blocked isocyanate group and a nonionic hydrophilic group represented by the general formula (I) or (II) is preferable.

  Specifically, the above-mentioned production method includes 20 to 150 ° C., preferably 75 to 95 ° C., optionally reduced pressure, and 5 minutes to 20 hours, preferably 10 minutes to 10 hours. It is appropriate to remove some or all of the above. If the temperature is too low, the exchange reaction of the alkoxy group in the block polyisocyanate compound (C1-1) having a nonionic hydrophilic group is slowed to reduce the production efficiency. On the other hand, if the temperature is too high, the nonionic hydrophilic group is obtained. Since the degradation degradation of the block polyisocyanate compound (C2) it has becomes intense and curability may be lowered, it is not desirable.

Block polyisocyanate compound having nonionic hydrophilic group (C2-2)
The block polyisocyanate compound (C2-2) having a nonionic hydrophilic group is specifically represented by the following general formula (V) described in the description of the block polyisocyanate compound (C1) having a nonionic hydrophilic group, for example. )

Wherein (V), ^{R 6} and ^{R 7} independently represent a hydrocarbon group having 1 to 12 carbon atoms. ]
It can obtain by making the block polyisocyanate compound (C1-2) which has a block isocyanate group shown by and which has a nonionic hydrophilic group react with the said secondary alcohol (c4).

In this case, R ⁷ in the blocked isocyanate group in the blocked polyisocyanate compound (C1-2) having the hydrophilic group is represented by the following general formula (VII)

[In Formula (VII), R ² , R ⁴ and R ⁵ independently represent a hydrocarbon group having 1 to 12 carbon atoms, and R ³ represents a linear or branched group having 1 to 12 carbon atoms. Represents an alkylene group. ]
It is substituted with a group represented by

  In this case, the obtained blocked polyisocyanate compound (C1-2) is a blocked isocyanate group represented by the following general formula (III).

Wherein ^{(III), R 2, R} 3, R 4 and ^{R 5} are as defined above, ^{R 6} represents a hydrocarbon group of 1 to 12 carbon atoms. ]
Have

The reaction of the block polyisocyanate compound (C1-2) having a nonionic hydrophilic group and the secondary alcohol (c4) is, for example, in the block isocyanate group in the block polyisocyanate compound (C1-2) having a nonionic hydrophilic group. There is no particular limitation as long as R ⁷ can be substituted with the group represented by the general formula (VII). Among them, part or all of the alcohol derived from R ⁷ in the block polyisocyanate compound (C1-2) having a hydrophilic group is distilled out of the system by heating, decompression, etc., and the reaction is promoted, A method of obtaining a blocked polyisocyanate compound (C2-2) having a nonionic hydrophilic group having a blocked isocyanate group represented by the general formula (III) is preferred.

  Specifically, the above-mentioned production method includes 20 to 150 ° C., preferably 75 to 95 ° C., optionally reduced pressure, and 5 minutes to 20 hours, preferably 10 minutes to 10 hours. It is preferable to remove part or all of the above. If the temperature is too low, the exchange reaction of the alkoxy group in the block polyisocyanate compound (C1-2) having a nonionic hydrophilic group is slowed, resulting in a decrease in production efficiency. On the other hand, if the temperature is too high, the nonionic hydrophilic group is obtained. Since the degradation degradation of the block polyisocyanate compound (C2) it has becomes intense and the curability may be lowered, it is not desirable.

  In addition, in the production of the block polyisocyanate compound (C2) having a nonionic hydrophilic group, the blending ratio of the block polyisocyanate compound (C1) having the nonionic hydrophilic group and the secondary alcohol (c4) is the nonionic hydrophilic property obtained. From the viewpoint of the reactivity and production efficiency of the block polyisocyanate compound (C) having a group, the secondary alcohol (c4) is based on 100 parts by mass of the solid content of the block polyisocyanate compound (C1) having a nonionic hydrophilic group. It is preferably in the range of 5 to 500 parts by mass, and more preferably in the range of 10 to 200 parts by mass. If it is less than 5 mass parts, the reaction rate of the block polyisocyanate compound (C1) and secondary alcohol (c4) which has a hydrophilic group may be too slow. Moreover, when it exceeds 500 mass parts, the density | concentration of the block polyisocyanate compound (C2) which has a nonionic hydrophilic group to produce | generate may become low too much, and manufacturing efficiency may fall.

  In the reaction of the block polyisocyanate compound (C1) having a nonionic hydrophilic group and the secondary alcohol (c4), in order to adjust the molecular weight of the block polyisocyanate compound (C2) having a nonionic hydrophilic group, You may perform the said removal operation, after adding a polyol compound to the block polyisocyanate compound (C1) and secondary alcohol (c4) which has a nonionic hydrophilic group.

  Among the blocked polyisocyanate compounds (C) having a nonionic hydrophilic group, the reason why the compound (C2-1) and the compound (C2-2) are particularly excellent in stability in water is because they have a nonionic hydrophilic group, It is presumed that the blocked isocyanate group has a low polarity and is difficult to hydrolyze because it has a hydrocarbon group having a branched structure.

  In one embodiment, the blocked polyisocyanate compound (C) having a nonionic hydrophilic group is a blocked isocyanate group represented by the following general formula (I):

[In the formula (I), R ¹ , R ² , R ⁴ and R ⁵ independently represent a hydrocarbon group having 1 to 12 carbon atoms, and R ³ is a straight chain having 1 to 12 carbon atoms or Represents a branched alkylene group. ],
Blocked isocyanate group represented by the following general formula (II)

[In formula (II), R ² , R ³ , R ⁴ and R ⁵ are the same as above. ]
And a blocked isocyanate group represented by the following general formula (III)

Wherein ^{(III), R 2, R} 3, R 4 and ^{R 5} are as defined above, ^{R 6} represents a hydrocarbon group having 1 to 12 carbon atoms. ]
It is a block polyisocyanate compound having at least one type of blocked isocyanate group selected from.

  The number average molecular weight of the block polyisocyanate compound (C) having a nonionic hydrophilic group is compatible with other paint components, the smoothness of the coating film formed by the aqueous first colored paint (X) of the present invention, From the standpoints of film quality, adhesion, water resistance and chipping resistance, it is preferably in the range of 600 to 30,000. The upper limit of the number average molecular weight is more preferably 10,000 from the viewpoints of compatibility with other paint components and the smoothness and sharpness of the coating film formed by the aqueous first colored paint (X) of the present invention. 5,000 is more preferable. The lower limit is more preferably 900 and even more preferably 1,000 from the viewpoints of the adhesion, water resistance and chipping resistance of the coating film formed with the aqueous first colored paint (X) of the present invention.

  The block polyisocyanate compound (C) having a nonionic hydrophilic group may be mixed in advance with a surfactant. In this case, from the viewpoint of the stability of the aqueous first colored paint (X) of the present invention, the surfactant is preferably a nonionic surfactant.

  The content of the block polyisocyanate compound (C) having the nonionic hydrophilic group in the aqueous first colored paint (X) of the present invention is 5 to 5 based on the total amount of resin solids in the first colored paint (X). 40% by mass, preferably 7 to 35% by mass, more preferably 10 to 30% by mass, from the viewpoint of chipping resistance, adhesion, finish, weather resistance and gasohol resistance of the resulting coating film It is.

Conductive pigment (D)
The conductive pigment (D) is not particularly limited as long as it can impart conductivity to the coating film to be formed, and has any shape such as particles, flakes, and fibers (including whiskers). But it can be used. Specific examples include conductive carbon such as conductive carbon black, carbon nanotube, carbon nanofiber, and carbon microcoil; metal powder such as silver, nickel, copper, graphite, and aluminum, and further doped with antimony. Tin oxide coated with phosphorus, tin oxide doped with phosphorus, acicular titanium oxide surface coated with tin oxide / antimony, antimony oxide, zinc antimonate, indium tin oxide, carbon and graphite whiskers coated with tin oxide, etc. A pigment having a flaky mica surface coated with a conductive metal oxide such as tin oxide or antimony-doped tin oxide; and a conductive pigment containing tin oxide and phosphorus on the surface of titanium dioxide particles. These can be used alone or in combination of two or more. Of these, conductive carbon can be particularly preferably used.

  In the water-based first colored paint (X) used in the present invention, the content of the conductive pigment is 0.5 to 40% by mass based on the total amount of resin solids in the water-based first colored paint (X), Preferably it is 1-35 mass%, More preferably, it is 3-30 mass% from the point of the electroconductivity and light transmittance of the coating film obtained.

  In one embodiment, the aqueous first colored paint (X) used in the present invention is 10 to 60% by mass of a non-chlorine polyolefin based on the total amount of resin solids in the aqueous first colored paint (X). Resin (A), 10-50% by mass of aqueous polyurethane resin (B), 5-40% by mass of blocked isocyanate compound (C) having a nonionic hydrophilic group, and 0.5-40% by mass of conductivity. A pigment (D).

Other components The water-based first colored paint (X) used in the present invention includes the non-chlorinated polyolefin resin (A), a specific aqueous polyurethane resin (B), and a block polyisocyanate compound having a nonionic hydrophilic group ( C), an electroconductive pigment (D) as an essential component, and further appropriately a hydroxyl group-containing acrylic resin, a hydroxyl group-containing polyester resin, a block polyisocyanate compound other than component (C), a melamine resin, a phenol resin, a polycarbonate resin And a resin component such as an epoxy resin.

  As the hydroxyl group-containing acrylic resin, a known water-soluble or water-dispersible hydroxyl group-containing acrylic resin which has been conventionally used in water-based paints can be used. The hydroxyl group-containing acrylic resin is prepared by, for example, a hydroxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer by a method known per se, such as solution polymerization. According to the method, it can be produced by copolymerization.

  The hydroxyl group-containing polymerizable unsaturated monomer is a compound having at least one hydroxyl group and one polymerizable unsaturated bond in one molecule. For example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meta ) Monoesterified product of glycol and acrylic acid or methacrylic acid such as acrylate and polyethylene glycol mono (meth) acrylate; Compound obtained by ring-opening polymerization of ε-caprolactone to monoesterified product of polyhydric alcohol and acrylic acid or methacrylic acid Etc.

Other polymerizable unsaturated monomers copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer can be appropriately selected and used depending on the properties desired for the hydroxyl group-containing acrylic resin. Specific examples of the monomer are listed below. These can be used alone or in combination of two or more.
(I) Alkyl or cycloalkyl (meth) acrylate: For example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, dodecyl (meth) Acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) Acrylate, cyclododecyl (meth) acrylate, tricyclodecanyl (meth) acrylate.
(Ii) Polymerizable unsaturated monomer having an isobornyl group: for example, isobornyl (meth) acrylate.
(Iii) Polymerizable unsaturated monomer having an adamantyl group: for example, adamantyl (meth) acrylate and the like.
(Iv) Polymerizable unsaturated monomer having a tricyclodecenyl group: For example, tricyclodecenyl (meth) acrylate and the like.
(V) Aromatic ring-containing polymerizable unsaturated monomer: For example, benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene and the like.
(Vi) Polymerizable unsaturated monomer having an alkoxysilyl group: For example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- ( (Meth) acryloyloxypropyltriethoxysilane and the like.
(Vii) Polymerizable unsaturated monomer having a fluorinated alkyl group: For example, perfluoroalkyl (meth) acrylate such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; fluoroolefin and the like.
(Viii) A polymerizable unsaturated monomer having a photopolymerizable functional group such as a maleimide group.
(Ix) Vinyl compound: For example, N-vinyl pyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate and the like.
(X) Phosphoric acid group-containing polymerizable unsaturated monomer: For example, 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, 2-methacryloyloxypropyl acid phosphate and the like.
(Xi) Carboxy group-containing polymerizable unsaturated monomer: For example, (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and the like.
(Xii) Nitrogen-containing polymerizable unsaturated monomer: For example, (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N- Dimethylaminopropyl (meth) acrylamide, methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, 2- (methacryloyloxy) ethyltrimethylammonium chloride, an adduct of glycidyl (meth) acrylate and amines, and the like.
(Xiii) A polymerizable unsaturated monomer having at least two polymerizable unsaturated groups in one molecule: for example, allyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate and the like.
(Xiv) Epoxy group-containing polymerizable unsaturated monomer: For example, glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) ) Acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, allyl glycidyl ether and the like.
(Xv) (meth) acrylate having a polyoxyethylene chain whose molecular end is an alkoxy group.
(Xvi) Polymerizable unsaturated monomer having a sulfonic acid group: For example, 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, allylsulfonic acid, 4-styrenesulfonic acid, etc .; Sodium salt and ammonium salt.
(Xvii) Polymerizable unsaturated monomer having an ultraviolet-absorbing functional group: For example, 2-hydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2-hydroxy-4- (3-acryloyloxy-2) -Hydroxypropoxy) benzophenone, 2,2'-dihydroxy-4- (3-methacryloyloxy-2-hydroxypropoxy) benzophenone, 2,2'-dihydroxy-4- (3-acryloyloxy-2-hydroxypropoxy) benzophenone, 2- (2′-hydroxy-5′-methacryloyloxyethylphenyl) -2H-benzotriazole and the like.
(Xviii) Light-stable polymerizable unsaturated monomer: For example, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloyloxy-2,2,6, 6-tetramethylpiperidine, 4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4- (meth) acryloylamino-2,2,6 , 6-tetramethylpiperidine, 1- (meth) acryloyl-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6 6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2 2,6,6-tetramethylpiperidine, and the like.
(Xix) polymerizable unsaturated monomer having a carbonyl group: for example, acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrol, vinyl alkyl ketone having 4 to 7 carbon atoms (for example, vinyl Methyl ketone, vinyl ethyl ketone, vinyl butyl ketone) and the like.
(Xx) Polymerizable unsaturated monomer having an acid anhydride group: for example, maleic anhydride, itaconic anhydride, citraconic anhydride and the like.

  The hydroxyl group-containing acrylic resin usually has a hydroxyl value of 10 to 150, particularly 50 to 100, an acid value of 60 or less, particularly 50 or less, and a weight average molecular weight of 1000 to 100,000, particularly 2000 to 60000.

  In the present specification, the weight average molecular weight of the hydroxyl group-containing acrylic resin and the number average molecular weight of the hydroxyl group-containing polyester resin and the melamine resin described below are the retention times measured using a gel permeation chromatograph (GPC) ( (Retention capacity) is a value obtained by converting to the molecular weight of polystyrene by the retention time (retention capacity) of standard polystyrene having a known molecular weight measured under the same conditions. Specifically, “HLC-8120GPC” (trade name, manufactured by Tosoh Corporation) is used as a gel permeation chromatograph apparatus, and “TSKgel G4000HXL”, “TSKgel G3000HXL”, “TSKgel G2500HXL” and “TSKgel” are used as columns. G2000HXL "(trade name, all manufactured by Tosoh Corporation), using a differential refractometer as the detector, mobile phase: tetrahydrofuran, measurement temperature: 40 ° C, flow rate: 1 mL / min Can be measured below.

  In the water-based first colored paint (X) used in the present invention, the amount used when a hydroxyl group-containing acrylic resin is used is 5 to 35 masses based on the total resin solid content in the first colored paint (X). %, Preferably 10 to 25% by mass, from the viewpoint of chipping resistance, adhesion, finish, weather resistance and gasohol resistance of the resulting coating film.

  As the hydroxyl group-containing polyester resin, a water-soluble or water-dispersible hydroxyl group-containing polyester resin that has been conventionally used in water-based paints can be used. For example, a polybasic acid and a polyhydric alcohol can be used. It can be obtained by an esterification reaction with an excess of hydroxyl groups by a known method. A polybasic acid is a compound having two or more carboxyl groups in one molecule. For example, phthalic acid, isophthalic acid, terephthalic acid, tetrahydrophthalic acid, hexahydrophthalic acid, 1,4-cyclohexanedicarboxylic acid, pyro Examples include merit acid, itaconic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, dimer acid, hymic acid, succinic acid, het acid, and anhydrides thereof. The polyhydric alcohol is a compound having two or more hydroxyl groups in one molecule, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, butylene glycol, hexanediol, 2-ethyl-2- Examples include butyl-1,3-propanediol, cyclohexanedimethanol, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol, sorbitol and the like. Introduction of a hydroxyl group can be performed, for example, by using a polyhydric alcohol having 3 or more hydroxyl groups in one molecule. Further, as the polyester resin, a fatty acid-modified polyester resin modified with a fatty acid such as soybean oil fatty acid, castor oil fatty acid, dehydrated castor oil fatty acid or the like can also be used. Further, the polyester resin may be modified with an epoxy compound such as butyl glycidyl ether, alkylphenyl glycidyl ether, or neodecanoic acid glycidyl ester.

  The hydroxyl group-containing polyether resin usually has a hydroxyl value of 10 to 160 mgKOH / g, particularly 50 to 85 mgKOH / g, an acid value of 50 mgKOH / g or less, particularly 1 to 30 mgKOH / g, and a number average molecular weight of 1. In the range of 10000 to 20,000, particularly 1,300 to 10,000 is preferable.

  In the aqueous first colored paint (X) used in the present invention, the amount of the hydroxyl group-containing polyester resin used is 2 to 20 mass based on the total resin solid content in the first colored paint (X). %, Preferably 5 to 15% by mass, from the viewpoint of chipping resistance, adhesion, finish, weather resistance and gasohol resistance of the resulting coating film.

  The blocked polyisocyanate compound other than component (C) is obtained by adding a blocking agent to the isocyanate group of the polyisocyanate compound, and the blocked polyisocyanate compound produced by the addition is stable at room temperature, but the coating film It is desirable that the block agent can be dissociated to regenerate free isocyanate groups when heated to a baking temperature (usually about 80 to about 200 ° C.). Examples of the blocking agent that satisfies such requirements include, for example, phenol, lactam, alcohol, ether, oxime, active methylene, mercaptan, acid amide, imide, amine, imidazole, and pyrazole. And the like blocking agents.

  As the melamine resin, an alkyl etherified melamine resin etherified with an alkyl group such as methyl, ethyl, n-butyl, isobutyl, hexyl, 2-ethylhexyl is particularly preferable. These melamine resins may further have a methylol group, an imino group or the like. The melamine resin usually has a number average molecular weight in the range of 500 to 5,000, particularly 800 to 3,000.

  The water-based first colored paint (X) used in the present invention is further colored pigment, extender pigment, organic solvent, silane coupling agent, curing catalyst, thickener, antifoaming agent, surface conditioner, film-forming aid. An additive for paint such as an agent can be contained.

  Examples of color pigments include titanium oxide, carbon black, chrome lead, ocher, yellow iron oxide, Hansa Yellow, pigment yellow, chrome orange, chrome vermillion, permanent orange, amber, permanent red, brilliant carmine, fast violet, and methyl violet. Examples include rake, ultramarine, bitumen, cobalt blue, phthalocyanine blue, pigment green, naphthol green, and aluminum paste. These can be used alone or in combination of two or more.

  When the aqueous first colored paint (X) used in the present invention contains the above-described colored pigment, the content of the colored pigment is based on the total resin solid mass in the aqueous first colored paint (X). It is suitable from the viewpoint of the light transmittance and finishing property of the coating film to be obtained in the range of 1 to 180% by mass, preferably 2 to 140% by mass, and more preferably 4 to 130% by mass.

  Examples of extender pigments include talc, silica, calcium carbonate, barium sulfate, and zinc white (zinc oxide). These can be used alone or in combination of two or more.

  When the aqueous first colored paint (X) used in the present invention contains the extender pigment, the content of the extender pigment is based on the total mass of the resin solid content in the aqueous first colored paint (X). It is suitable from a viewpoint of the light transmittance of the coating film obtained and chipping resistance that it is 1-150 mass%, Preferably it is 5-130 mass%, More preferably, it exists in the range of 10-110 mass%.

The organic solvent is not particularly limited as long as it can mix and dissolve or disperse the above-described resin components. For example, aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, alcohol solvents, ester solvents And solvents such as ketone solvents.

  Examples of the silane coupling agent include 2- (3,4 epoxy cyclohexyl) ethyl trialkoxysilane, 3-glycidoxypropyltrialkoxysilane, 3-glycidoxypropylmethyl dialkoxysilane, N-2- (amino Ethyl) -3-aminopropylmethyl dialkoxysilane, N-2- (aminoethyl) -3-aminopropyltrialkoxysilane, 3-aminopropyltrialkoxysilane, 3-aminopropylmethyl dialkoxysilane, 3-mercaptopropyl Methyl dialkoxysilane, 3-mercaptopropyltrialkoxysilane, N-phenyl-3-aminopropyltrialkoxysilane, 3-ureidopropyltrialkoxysilane, 3-chloropropyltrialkoxysilane, bis (trialkoxy) Rirupuropiru) tetrasulfide, 3-isocyanate propyl trialkoxysilane can be exemplified. These can be used alone or in combination of two or more.

  The solid content concentration of the aqueous first colored paint (X) is usually preferably 20 to 70% by mass, more preferably 30 to 60% by mass, and still more preferably 35 to 60% by mass.

  The coating of the water-based first colored paint (X) used in the present invention is not particularly limited. For example, the wet paint film is formed by a coating method such as air spray coating, airless spray coating, rotary atomization coating, curtain coat coating or the like. Can be formed. In these coating methods, electrostatic application may optionally be performed. Of these, air spray coating is particularly preferred. The coating amount of the aqueous first colored paint (X) is preferably such that the film thickness based on the cured coating film is generally 1 to 20 μm, particularly 3 to 15 μm. The aqueous first colored paint (X) can be applied as described above to form a first colored coating film.

  From the viewpoint of chipping resistance, adhesion, finish, and weather resistance of the coating film to be formed, the cured coating film obtained by applying and curing the aqueous first colored paint (X) has a thickness of 5 μm It is preferable that the average light transmittance at a wavelength of 360 to 420 nm is less than 1%, particularly less than 0.5%. The average light transmittance can be set by adjusting the thickness of the cured coating film and the amount of pigment contained in the average light transmittance.

  Here, the average light transmittance of the cured coating film having a thickness of 5 μm at a wavelength of 360 to 420 nm can be measured by the following method.

  First, on the polytetrafluoroethylene plate, the aqueous first colored paint (X) is applied and cured so that the thickness of the coating film when cured is 5 μm. Next, the coating film obtained by curing is peeled off and collected, and the average light transmittance in a wavelength range of 360 to 420 nm is measured using a spectrophotometer. As the spectrophotometer, for example, “SolidSpec-3700” (trade name, manufactured by Shimadzu Corporation) can be used.

Process (2)
An aqueous second colored paint (Y) is applied on the first colored coating film.

  The solid content of the first colored coating film can be adjusted by, for example, preheating (preheating), air blowing, etc. before applying the aqueous second colored paint (Y). Then, even if it does not preheat after application | coating of water-based 1st coloring coating material (X), the multilayer coating film excellent in chipping resistance, adhesiveness, finishing property, weather resistance, and gasohol resistance can be obtained. When preheating is not performed, it is preferable that the coating is performed at room temperature (about 20 to about 35 ° C.) for about 30 seconds to 5 minutes after the application of the aqueous first colored paint (X). Thereby, a mixed layer of the first colored coating film and the second colored coating film can be prevented.

  In the case of preheating, the preheating is usually performed by directly applying the coated object in a drying furnace at a temperature of about 50 to about 110 ° C., preferably about 60 to about 80 ° C. for about 1 to 30 minutes. Or it can carry out by heating indirectly.

  Moreover, the said air blow can be normally performed by spraying the air heated at the normal temperature or the temperature of about 25 degreeC-about 80 degreeC on the coating surface of the to-be-coated article.

Water-based second colored paint (Y)
As the water-based second colored paint (Y) used in the present invention, for example, those known per se that are usually used in the coating of automobile bodies can be used.

  The aqueous second colored paint (Y) can be generally prepared by mixing and dispersing a base resin, a crosslinking agent, a pigment and the like in an aqueous medium.

  As the base resin, for example, a resin containing a carboxyl group and a hydroxyl group is preferably used. Examples of the base resin include acrylic resin, polyester resin, polyether resin, polycarbonate resin, and polyurethane resin.

  It is preferable that the carboxyl group and the carboxyl group in the hydroxyl group-containing resin are neutralized. The neutralization is preferably performed using a basic substance before mixing with a crosslinking agent or the like.

  Examples of basic substances used for neutralization include ammonia; primary monoamines such as ethylamine, propylamine, butylamine, benzylamine, monoethanolamine, neopentanolamine, 2-aminopropanol, and 3-aminopropanol; Secondary monoamines such as diethylamine, diethanolamine, di-n- or diisopropanolamine, N-methylethanolamine, N-ethylethanolamine; N, N-dimethylethanolamine, trimethylamine, triethylamine, triisopropylamine, methyldiethanolamine, etc. And tertiary amines such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, and polyamines such as methylaminopropylamine. These may be used either alone or in combination of two or more thereof.

  The amount of the basic substance used for neutralization is usually in the range of 0.1 to 1.5 equivalents, particularly 0.3 to 1.2 equivalents, based on the carboxyl group and the carboxyl group in the hydroxyl group-containing resin. It is preferable that

  The base resin preferably has an acid value in the range of usually 10 to 150 mgKOH / g, particularly 30 to 100 mgKOH / g, from the viewpoint of water dispersibility and the like. In addition, the base resin preferably has a hydroxyl value in the range of usually 10 to 150 mgKOH / g, particularly 30 to 100 mgKOH / g, from the viewpoint of curability and the like.

  In addition, the base resin is usually a number average within the range of 3000 to 100,000, particularly 5000 to 50000 in the acrylic resin, and usually 500 to 50000, particularly 3000 to 30000 in the polyester resin from the viewpoint of weather resistance and the like. It preferably has a molecular weight.

  When a carboxyl group- and hydroxyl group-containing acrylic resin is used as the base resin, a carboxyl group- and hydroxyl group-containing acrylic resin produced by emulsion polymerization in the presence of a dispersion stabilizer can also be used.

  In the case of the acrylic resin produced by the emulsion polymerization, those having a number average molecular weight in the range of usually 100,000 or more, particularly 200000 to 2000000 are preferable.

  Examples of the dispersion stabilizer used in the emulsion polymerization include nonionic surfactants and anionic surfactants, and aqueous resins such as acrylic resins having an acid value of about 10 to 150 mgKOH / g and a number average molecular weight of about 5000 to 30000. Can be preferably used.

  The emulsion polymerization can be carried out by a method known per se.

  As the base resin, among them, an acrylic emulsion produced by a multistage polymerization method using a carboxyl group-containing unsaturated monomer as a copolymerization component can obtain an aqueous second colored paint (Y) excellent in coating workability. Therefore, it is preferable. That is, first, a polymerization reaction is carried out using a monomer mixture having a composition containing no or almost no carboxyl group-containing unsaturated monomer (usually 3% by mass or less in all monomers), and then containing a carboxyl group-containing unsaturated monomer ( The acrylic emulsion obtained by carrying out the polymerization reaction using a monomer mixture having a composition of 5 to 30% by mass in the total monomers usually has a viscosity developing effect by neutralization with a basic substance, This is preferable because an aqueous second colored paint (Y) excellent in coating workability such as sagging property can be obtained.

  As a crosslinking agent, at least 1 sort (s) chosen from the crosslinking agent which can react with a hydroxyl group, such as a melamine resin, a block polyisocyanate compound, a water dispersible block polyisocyanate compound, can be used, for example.

  The blending ratio of the base resin and the crosslinking agent in the aqueous second colored paint (Y) is generally 60 to 100% by weight, particularly 65 to 95% by weight, more particularly 70%, based on the total solid content of both components. It is preferred that the content of .about.90% by mass and the crosslinking agent is generally in the range of 0 to 40% by mass, particularly 5 to 35% by mass, more particularly 10 to 30% by mass.

  The pigment is not particularly limited, and for example, inorganic and organic pigments, extenders, glitter pigments, and the like can be preferably used. Examples of the color pigment include titanium oxide, zinc white, carbon black, cadmium red, molybdenum red, chromium yellow, chromium oxide, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, selenium pigment, Examples include perylene pigments. Examples of the extender pigment include talc, clay, kaolin, barita, barium sulfate, barium carbonate, calcium carbonate, silica, and alumina white. Examples of the bright pigment include aluminum powder, mica powder, and mica powder coated with titanium oxide.

  The amount of the pigment blended is generally in the range of 0.1 to 200% by mass, particularly 1 to 100% by mass, based on the total solid content of the base resin and the crosslinking agent.

  For the water-based second colored paint (Y), a curing catalyst, a dispersant, an anti-settling agent, an antifoaming agent, a thickening agent, an ultraviolet absorber, a light stabilizer, a surface conditioner, an antioxidant, etc. are optionally selected. Can be used as appropriate.

  The non-volatile concentration during application of the aqueous second colored paint (Y) is usually preferably 15 to 65% by mass, and the single coating film can be an opaque or transparent solid or metallic coating film. In this specification, an opaque coating means a coating having a light transmittance of less than 5% in a cured coating of 20 μm of a coating alone, and a transparent coating means a light beam in the cured coating of 20 μm. It means a coating film having a transmittance of 5% or more.

  The water-based second colored paint (Y) is optionally electrostatically applied, for example, by air spray, airless spray, rotary atomization coating, etc., and the film thickness based on the cured coating is generally 5 to 30 μm, particularly 10 It can be painted to ˜25 μm.

  In the present invention, the aqueous second colored paint (Y) is applied on the first colored coating film, and then the clear paint (Z) is applied. Optionally, prior to the application of the clear paint (Z), an aqueous The second colored coating film obtained by applying the second colored paint (Y) may be pre-dried at a temperature of about 50 to 100 ° C.

  By this preliminary drying, the volatile components in the second colored coating film can be volatilized to some extent.

  Since the coating film is dried and solidified to some extent by the preliminary drying, the solvent, the low-molecular resin component, and the like contained in the coating film when the clear paint (Z) is applied onto the second colored coating film Even if it penetrates and diffuses into the colored coating film, it can suppress a decrease in viscosity of the second colored coating film, and can suppress reflow of the bright pigment when using the bright pigment, Generation of metal unevenness or the like can be prevented.

  In particular, when the multi-layer coating film forming method of the present invention forms a high-white pearl-tone multi-layer coating film, the second colored paint (Y) contains a white base paint containing a white pigment and a mica powder. The interference pearl color base paint to be applied can be sequentially applied. After the white base paint is applied, it may not be pre-dried or may be pre-dried at a temperature of about 50 to 100 ° C, or may be baked at a temperature of about 100 to 140 ° C.

Step (3)
The clear paint (Z) is applied on the aqueous second colored coating film formed of the aqueous second colored paint (Y) as described above.

Clear paint (Z)
The clear paint contains, for example, a resin component such as a base resin and a crosslinking agent, an organic solvent, water, and the like, and further includes a curing catalyst, an ultraviolet absorber, a light stabilizer, a coating surface conditioner, a rheology control agent, An organic solvent-based or water-based thermosetting coating containing additives such as antioxidants, antifoaming agents, waxes, etc., and the lower layer coating can be visually recognized through the formed clear coating Those having a degree of transparency can be used.

  Examples of the base resin include acrylic resin, polyester resin, alkyd resin, fluororesin, urethane resin, and silicon-containing resin containing at least one reactive functional group such as a hydroxyl group, a carboxyl group, a silanol group, and an epoxy group. In particular, a hydroxyl group-containing acrylic resin (K) is preferable.

Hydroxyl group-containing acrylic resin (K)
The hydroxyl group-containing acrylic resin (K) can be produced by copolymerizing monomer components composed of (k1) a hydroxyl group-containing polymerizable unsaturated monomer and (k2) other polymerizable unsaturated monomers by a conventional method.

  The hydroxyl group-containing polymerizable unsaturated monomer (k1) is a compound having one hydroxyl group and one polymerizable unsaturated bond in each molecule.

  Examples of the hydroxyl group-containing polymerizable unsaturated monomer (k1) include a secondary hydroxyl group-containing polymerizable unsaturated monomer (k1-1) and a hydroxyl group (excluding secondary hydroxyl group) -containing polymerizable unsaturated monomer (k1-2). Can do.

  Examples of the secondary hydroxyl group-containing polymerizable unsaturated monomer (k1-1) include ester moieties such as 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl (meth) acrylate. A polymerizable unsaturated monomer having a secondary hydroxyl group having 2 to 8, particularly 3 to 6, more particularly 3 or 4 carbon atoms of the alkyl group; (meth) acrylic acid and an epoxy group-containing compound (for example, Cardura E10, trade name) And adducts with Hexion Specialty Chemical Co., Ltd., neodecanoic acid glycidyl ester). Among these, 2-hydroxypropyl (meth) acrylate is particularly preferred from the viewpoints of chipping resistance, adhesion, finish, weather resistance, and gasohol resistance of the resulting multilayer coating film.

  The monomer (k1-1) can be used alone or in combination of two or more.

  The hydroxyl group (excluding secondary hydroxyl group) -containing polymerizable unsaturated monomer (k1-2) is a compound having one hydroxyl group (excluding secondary hydroxyl group) and one polymerizable unsaturated bond in one molecule.

  Examples of the monomer include (meth) acrylic acid such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate, and a dihydric alcohol having 2 to 10 carbon atoms. And monoesterified products (excluding those having secondary hydroxyl groups); hydroxyl group-containing monomers modified by ring-opening polymerization reaction of ε-caprolactone (excluding those having secondary hydroxyl groups), and the like.

  As the hydroxyl group-containing monomer modified by ring-opening polymerization reaction of ε-caprolactone, a commercially available product can be used. Examples of commercially available products include “Placcel FA-1”, “Placcel FA-2”, “ Plaxel FA-3, Plaxel FA-4, Plaxel FA-5, Plaxel FM-1, Plaxel FM-2, Plaxel FM-3, Plaxel FM-4, Plaxel FM-5 "(all of which are trade names manufactured by Daicel Chemical Industries, Ltd.).

  The said monomer (k1-2) can be used by 1 type or in combination of 2 or more types.

  The other polymerizable unsaturated monomer (k2) is a monomer other than the hydroxyl group-containing polymerizable unsaturated monomer (k1), specifically, a compound having one polymerizable unsaturated bond in one molecule. is there. Specific examples of the unsaturated monomer (k2) are listed in the following (1) to (7).

(1) Acid group-containing polymerizable unsaturated monomer The acid group-containing polymerizable unsaturated monomer is a compound having one acid group and one polymerizable unsaturated bond in each molecule. Examples of the monomer include carboxyl group-containing monomers such as (meth) acrylic acid, crotonic acid, itaconic acid, maleic acid and maleic anhydride; sulfonic acid group-containing monomers such as vinyl sulfonic acid and sulfoethyl (meth) acrylate; 2 Acidic phosphoric acid such as-(meth) acryloyloxyethyl acid phosphate, 2- (meth) acryloyloxypropyl acid phosphate, 2- (meth) acryloyloxy-3-chloropropyl acid phosphate, 2-methacryloyloxyethylphenyl phosphate Examples include ester monomers. These can be used alone or in combination of two or more.

(2) Esterified product of acrylic acid or methacrylic acid and C1-C20 monohydric alcohol Specifically, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl acrylate, n- Butyl (meth) acrylate, iso-butyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, isomyristyl (meth) acrylate, stearyl (meth) acrylate, iso Stearyl acrylate (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, cyclohexyl (meth) Examples include acrylate and isobornyl (meth) acrylate.

  Of the esterified product of acrylic acid or methacrylic acid and a monohydric alcohol having 1 to 20 carbon atoms, an alicyclic hydrocarbon group having 6 to 20 carbon atoms is selected from the viewpoint of improving the finished appearance and achieving both coating film hardness. The polymerizable unsaturated monomer (k2-1) to be contained can be preferably used.

  Typical examples of the alicyclic hydrocarbon group having 6 to 20 carbon atoms include a cyclohexyl group, a cyclooctyl group, a cyclododecyl group, an isobornyl group, an adamantyl group, and a tricyclodecanyl group.

  Specific examples of the unsaturated monomer (k2-1) include, for example, cyclohexyl (meth) acrylate, 4-methylcyclohexylmethyl (meth) acrylate, 4-ethylcyclohexylmethyl (meth) acrylate, and 4-methoxycyclohexylmethyl (meth). Cycloalkyl (meth) acrylates such as acrylate, tert-butylcyclohexyl (meth) acrylate, cyclooctyl (meth) acrylate, cyclododecyl (meth) acrylate; isobornyl (meth) acrylate, tricyclodecanyl (meth) acrylate, adamantyl ( Examples include bridged alicyclic hydrocarbon group-containing polymerizable unsaturated monomers such as (meth) acrylate, 3,5-dimethyladamantyl (meth) acrylate, and 3-tetracyclododecyl (meth) acrylate. It is possible. Of these, isobornyl (meth) acrylate is preferably used from the viewpoints of chipping resistance, adhesion, finish, weather resistance and gasohol resistance of the multilayer coating film obtained.

  When using an unsaturated monomer (k2-1), it is preferable that the mixture ratio exists in the range of 20-45 mass% with respect to the total amount of a monomer component, especially 30-40 mass%.

(3) Alkoxysilyl group-containing polymerizable unsaturated monomer Specifically, vinyltrimethoxysilane, vinyltriethoxysilane, acryloxyethyltrimethoxysilane, methacryloxyethyltrimethoxysilane, acryloxypropyltrimethoxysilane, methacryloxy Examples thereof include propyltrimethoxysilane, acryloxypropyltriethoxysilane, methacryloxypropyltriethoxysilane, vinyltris (β-methoxyethoxy) silane and the like. Among these, preferred alkoxysilyl group-containing polymerizable unsaturated monomers include vinyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, and the like.

  By using an alkoxysilyl group-containing polymerizable unsaturated monomer as a constituent component, in addition to the crosslinking bond between a hydroxyl group and an isocyanate group, a condensation reaction between alkoxylyl groups and a crosslinking bond between the alkoxysilyl group and the hydroxyl group are generated. Therefore, curability can be improved.

  When an alkoxysilyl group-containing polymerizable unsaturated monomer is used as a constituent component, the blending ratio is preferably in the range of 1 to 20% by mass, particularly 1 to 10% by mass, based on the total amount of monomer components.

(4) Aromatic vinyl monomer Specific examples include styrene, α-methylstyrene, vinyltoluene and the like.

  By using an aromatic polymerizable unsaturated monomer as a constituent component, the glass transition temperature of the resulting resin is increased, and a hydrophobic coating film having a high refractive index can be obtained. The effect of improving the finished appearance can be obtained.

  When an aromatic polymerizable unsaturated monomer is used as a constituent component, the blending ratio is preferably 5 to 30% by mass, particularly 10 to 20% by mass, based on the total amount of monomer components.

(5) Glycidyl group-containing polymerizable unsaturated monomer The glycidyl group-containing polymerizable unsaturated monomer is a compound having one glycidyl group and one polymerizable unsaturated bond in one molecule, specifically, glycidyl acrylate. And glycidyl methacrylate.

(6) Polymerizable unsaturated bond-containing nitrogen atom-containing compound For example, acrylamide, methacrylamide, dimethylacrylamide, N, N-dimethylpropylacrylamide, N-butoxymethylacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, diacetone Examples include acrylamide, N, N-dimethylaminoethyl (meth) acrylate, vinyl pyridine, vinyl imidazole, acrylonitrile, methacrylonitrile and the like.

(7) Other vinyl compounds For example, vinyl acetate, vinyl propionate, vinyl chloride, versatic acid vinyl ester and the like can be mentioned. Examples of the versatic acid vinyl ester include “Veoba 9” and “Veoba 10” (trade names, manufactured by Japan Epoxy Resin Co., Ltd.), which are commercially available products.

  As the other polymerizable unsaturated monomer (k2), the monomers represented by the above (1) to (7) may be used alone or in combination of two or more.

  The weight average molecular weight of the hydroxyl group-containing acrylic resin (K) is preferably 5000 to 18000, particularly preferably 8000 to 15000, from the viewpoint of the finished appearance and curability of the coating film.

  The glass transition temperature of the hydroxyl group-containing acrylic resin (K) is preferably −25 to 20 ° C., particularly preferably −15 to 10 ° C., from the viewpoint of the curability of the coating film and the finished appearance.

Here, the glass transition temperature (Tg) can be calculated by the following equation.
1 / Tg (° K) = (W1 / T1) + (W2 / T2) +
Tg (° C.) = Tg (° K) -273
In each formula, W1, W2,... Represent the respective weight percentages of the monomers used for the copolymerization, and T1, T2,... Represent Tg (° K) of the monomer homopolymer. T1, T2,... Are values according to Polymer Hand Book (Second Edition, edited by J. Brandup / E.H. Immergut).
The glass transition temperature (° C.) when the Tg of the homopolymer of the monomer is not clear is the static glass transition temperature. For example, a differential scanning calorimeter “DSC-50Q type” (manufactured by Shimadzu Corporation, trade name) is used. The sample was taken into a measuring cup, and the solvent was completely removed by vacuum suction, and then the change in calorie was measured in the range of −100 ° C. to + 100 ° C. at a temperature rising rate of 3 ° C./min to obtain the glass transition temperature.

  Secondary hydroxyl group-containing polymerizable unsaturated monomer (k1-1) out of the total amount of hydroxyl group-containing polymerizable unsaturated monomer (k1) in hydroxyl group-containing acrylic resin (K) from the viewpoint of improving the finished appearance of the coating film and pot life. It is preferable to contain 50-100 mass%, and it is more preferable to contain 80-100 mass%.

  Moreover, the hydroxyl value of a hydroxyl-containing acrylic resin (K) is 140-210 mgKOH / g from a viewpoint of sclerosis | hardenability and finished appearance, and it is preferable to exist in the range of 160-200 mgKOH / g.

  The mixing ratio of the hydroxyl group-containing polymerizable unsaturated monomer (k1) and the other polymerizable unsaturated monomer (k2) is determined based on the total monomer amount from the viewpoint of curability and the finished appearance of the cured coating film. The unsaturated monomer (k1) is preferably about 20 to 50% by mass, more preferably about 30 to 45% by mass, and the other unsaturated monomer (k2) is preferably about 50 to 80% by mass, more preferably It is about 55-70 mass%.

    The secondary hydroxyl group-containing polymerizable unsaturated monomer (k1-1) is contained in an amount of 10 to 50% by mass in the total amount of monomers in the hydroxyl group-containing acrylic resin (K) from the viewpoint of improving the finished appearance of the coating film and pot life. It is preferable that 20-45 mass% is contained, and it is more preferable.

    The acid value of the hydroxyl group-containing acrylic resin (K) is preferably about 0.5 to 30 mgKOH / g, particularly about 1 to 20 mgKOH / g, from the viewpoint of curability of the coating composition.

    A hydroxyl group-containing acrylic resin (K) can be obtained by copolymerizing the monomer mixture comprising the polymerizable unsaturated monomers (k1) and (k2).

  The hydroxyl group-containing acrylic resin (K) is preferably in the range of 30 to 70% by mass, more preferably 35 to 65% by mass, based on the total mass of the resin solid content in the clear paint (Z).

    The copolymerization method for copolymerizing the monomer mixture to obtain the hydroxyl group-containing acrylic resin (K) is not particularly limited, and a known copolymerization method can be used. Among them, a solution polymerization method in which polymerization is performed in the presence of a polymerization initiator can be preferably used.

    Examples of the organic solvent used in the solution polymerization method include aromatic solvents such as toluene, xylene, and Swazol 1000 (trade name, high-boiling petroleum solvent) manufactured by Cosmo Oil; ethyl acetate, butyl acetate, 3 -Ester solvents such as methoxybutyl acetate, ethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone, propyl propionate, butyl propionate, ethoxy ethyl Pionate can be mentioned.

    These organic solvents can be used singly or in combination of two or more, but it is preferable to use a high boiling ester solvent or ketone solvent from the viewpoint of the solubility of the acrylic resin. In addition, aromatic solvents having higher boiling points can be suitably used in combination.

    Examples of the polymerization initiator that can be used for copolymerization of the hydroxyl group-containing acrylic resin (K) include 2,2′-azobisisobutyronitrile, benzoyl peroxide, di-t-butyl peroxide, and di-t-amyl. Examples thereof include radical polymerization initiators known per se such as peroxide, t-butyl peroctoate, and 2,2′-azobis (2-methylbutyronitrile).

    A hydroxyl-containing acrylic resin (K) can be used individually or in combination of 2 or more types.

  In the clear paint (Z) used in the present invention, resins other than the hydroxyl group-containing acrylic resin (K) can optionally be used together. Specific examples include acrylic resins other than hydroxyl group-containing acrylic resins (K), polyester resins, polyether resins, polyurethane resins, polycarbonate resins, and the like. Among these, a hydroxyl group-containing polyester resin (L1), a hydroxyl group-containing polycarbonate resin (L2), and a hydroxyl group-containing polycarbonate are particularly preferable from the viewpoint of chipping resistance, adhesion, finish, weather resistance, and gasohol resistance of the coating film obtained. A polyester resin (L3) can be mentioned.

Hydroxyl-containing polyester resin (L1)
The hydroxyl group-containing polyester resin (L1) can be produced by a conventional method, for example, by an esterification reaction between a polybasic acid and a polyhydric alcohol. The polybasic acid is a compound having two or more carboxyl groups in one molecule. For example, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic acid, hexa And hydrophthalic acid, maleic acid, fumaric acid, itaconic acid, trimellitic acid, pyromellitic acid and their anhydrides. The polyhydric alcohol contains two or more hydroxyl groups in one molecule. For example, ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-diethyl-1,3 -Propanediol, neopentyl glycol, 1,9-nonanediol, 1,4-cyclohexanediol, hydroxy Diols such as valinic acid neopentyl glycol ester, 2-butyl-2-ethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethylpentanediol, hydrogenated bisphenol A, etc. , And trivalent or higher polyol components such as trimethylolpropane, trimethylolethane, glycerin, pentaerythritol, and the like, and 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, 2,2-dimethylol Examples thereof include hydroxycarboxylic acids such as pentanoic acid, 2,2-dimethylolhexanoic acid, and 2,2-dimethyloloctanoic acid.

  In addition, α-olefin epoxides such as propylene oxide and butylene oxide, monoepoxy compounds such as Cardura E10 (manufactured by Japan Epoxy Resin Co., Ltd., trade name, glycidyl ester of synthetic highly branched saturated fatty acid) and the like are reacted with acids, A compound may be introduced into the polyester resin.

    When introducing a carboxyl group into a polyester resin, for example, it can be introduced by adding an acid anhydride to a hydroxyl group-containing polyester and half-esterifying it.

  The hydroxyl group-containing polyester resin (L1) is preferably linear from the viewpoint of chipping resistance, adhesion, finish, weather resistance and gasohol resistance of the resulting coating film. In that respect, the polybasic acid is preferably adipic acid, and the polyhydric alcohol is ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1, 6-hexanediol is preferred.

  The hydroxyl value of the hydroxyl group-containing polyester resin (L1) is preferably 85 to 250 mgKOH / g, more preferably 100 to 220 mgKOH / g. The number average molecular weight of the hydroxyl group-containing polyester resin (L1) is preferably in the range of 500 to 2500, more preferably 800 to 2000.

Hydroxyl group-containing polycarbonate resin (L2)
The hydroxyl group-containing polycarbonate resin (L2) is a polycarbonate resin containing two or more carbonate groups and hydroxyl groups in the molecule.

  The hydroxyl group-containing polycarbonate resin (L2) is a compound obtained by polycondensation reaction of a known polyol and a carbonylating agent by a conventional method.

  Examples of the polyol that is a raw material for the hydroxyl group-containing polycarbonate resin (L2) include diols and trihydric or higher alcohols.

  Among the polyols used as a raw material for the hydroxyl group-containing polycarbonate resin (L2), diols include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6 hexanediol, 1,7- Linear aliphatic diols such as heptanediol, 1,8-octanediol, 1,9-nonanediol and 1,10-decanediol; 2-methyl-1,3-propanediol, 3-methyl-1,5 -Pentanediol, neopentyl glycol, 2-ethyl-1,6-hexanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 2-methyl -1,8 octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl 1,3-hexanediol Branched aliphatic diols of the above; alicyclic diols such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol; p-xylenediol, p-tetrachloroxylenediol, etc. And aromatic diols such as ether diols such as diethylene glycol and dipropylene glycol. These diols can be used alone or in combination of two or more.

  Among the polyols used as the raw material for the hydroxyl group-containing polycarbonate resin (L2), examples of the trivalent or higher alcohol include glycerin, trimethylolethane, trimethylolpropane, a trimethylolpropane dimer, and pentaerythritol. These trivalent or higher alcohols can be used alone or in combination of two or more.

  A known carbonylating agent can be used as the carbonylating agent used as a raw material for the hydroxyl group-containing polycarbonate resin (L2). Specifically, for example, alkylene carbonate, dialkyl carbonate, diaryl carbonate, phosgene and the like can be mentioned, and one of these can be used or two or more can be used in combination. Among these, preferred are ethylene carbonate, propylene carbonate, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, diphenyl carbonate and the like.

  The hydroxyl group-containing polycarbonate resin (L2) contains a hydroxyl group-containing polycarbonate resin having two hydroxyl groups (hereinafter sometimes referred to as “polycarbonate diol (L2-1)”), chipping resistance, adhesion, and finish. From the viewpoints of heat resistance, weather resistance and gasohol resistance.

  The polycarbonate diol (L2-1) can be synthesized by using only a diol as a polyol to be reacted with the carbonylating agent without using a polyhydric alcohol such as a trihydric or higher alcohol.

  The diol component of the polycarbonate diol (L2-1) is usually a diol having 6 or more carbon atoms, preferably 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms, and still more preferably 6 to 12 carbon atoms. Can do.

  Examples of the diol having 6 or more carbon atoms include an alicyclic diol having a cycloalkylene group having 6 or more carbon atoms and an aliphatic diol having an alkylene group having 6 or more carbon atoms.

  Examples of the alicyclic diol having a cycloalkylene group having 6 or more carbon atoms include 6 or more carbon atoms as a whole diol such as 1,3-cyclohexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. An alicyclic diol having 6 to 12 carbon atoms is preferable.

  Among these, 1,4-cyclohexanedimethanol is preferable from the viewpoint of chipping resistance.

  Examples of the aliphatic diol having an alkylene group having 6 or more carbon atoms include 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol. Linear aliphatic diols such as 3-methyl-1,5-pentanediol, 2-ethyl-1,6-hexanediol, 2,2-diethyl-1,3-propanediol, 2-butyl-2- Branched chain such as ethyl-1,3-propanediol, 2-methyl-1,8-octanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol Examples thereof include linear or branched aliphatic diols having 6 or more carbon atoms, preferably 6 to 10 carbon atoms, such as aliphatic diols.

  One of these linear aliphatic diols and branched aliphatic diols may be used, or both may be used in combination.

  Among the above, from the viewpoint of chipping resistance, a linear aliphatic diol is preferable, and 1,6-hexanediol is particularly preferable.

  The hydroxyl group-containing polycarbonate resin (L2) preferably has a number average molecular weight of 500 to 2500, more preferably 800 to 2000 from the viewpoint of chipping resistance, impact resistance at low temperature, and the like.

  Examples of commercially available products (L2) include UM-90, UH-100, UH-200, UC-100 (trade name, manufactured by Ube Industries).

Hydroxyl group-containing polycarbonate polyester resin (L3)
From the viewpoint of impact resistance at low temperatures, it is more preferable to use a hydroxyl group-containing polycarbonate polyester resin (L3).

  The hydroxyl group-containing polycarbonate polyester resin (L3) is produced, for example, by reacting the polycarbonate polyol (L2) with a cyclic ester compound by a known method.

Examples of the cyclic ester compound include δ-valerolactone, ε-caprolactone, ζ-enalactone, η-caprolactone, γ-valerolactone, δ-caprolactone, ε-enalactone, ξ-caprolactone, β-methyl-γ. -Valerolactone is mentioned, ε-caprolactone is particularly preferred.
The hydroxyl group-containing polycarbonate polyester resin (L3) preferably has a number average molecular weight of 500 to 2500, more preferably 800 to 2000, from the viewpoint of chipping resistance, impact resistance at low temperature, and the like.

  The total amount of the hydroxyl group-containing polyester resin (L1), the hydroxyl group-containing polycarbonate resin (L2) and the hydroxyl group-containing polycarbonate polyester resin (L3) is preferably 100% by mass or less based on the total solid content of the hydroxyl group-containing acrylic resin (K). More preferably, it exists in the range of 10-50 mass%.

  As the cross-linking agent of the clear paint, a melamine resin, urea resin, (block) polyisocyanate compound, epoxy compound, carboxyl group-containing compound, acid anhydride having a reactive functional group capable of reacting with the above functional group of the base resin Products, alkoxysilane group-containing compounds, etc., and polyisocyanate compounds (PI) are particularly preferred.

Polyisocyanate compound (PI)
The polyisocyanate compound (PI) is a compound having two or more isocyanate groups in one molecule. Examples of polyisocyanate compounds (PI) include those known for polyurethane production, such as aliphatic polyisocyanates, alicyclic polyisocyanates, araliphatic polyisocyanates, aromatic polyisocyanates, and derivatives of these polyisocyanates. Can do.

  Specific examples of the aliphatic polyisocyanate include trimethylene diisocyanate, tetramethylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, hexamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2- Fats such as butylene diisocyanate, 2,3-butylene diisocyanate, 1,3-butylene diisocyanate, 2,2,4-trimethyl-hexamethylene-1,6-diisocyanate, 2,6-diisocyanatomethylcaproate, lysine diisocyanate Lysine ester triisocyanate, 1,4,8-triisocyanatooctane, 1,6,11-triisocyanatoundecane, 1,8-diisocyanato-4-isocyanatomethyloctane, 3,6 tri diisocyanatohexane, and aliphatic triisocyanate such as 2,5,7-trimethyl-1,8-diisocyanato-5-isocyanatomethyl octane.

  Examples of the alicyclic polyisocyanate include 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate (common name: Isophorone diisocyanate), 4,4′-methylenebis (cyclohexyl isocyanate), methyl-2,4-cyclohexane diisocyanate, methyl-2,6-cyclohexane diisocyanate, 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane ( Common name: hydrogenated xylylene diisocyanate) or mixtures thereof, alicyclic diisocyanates such as norbornane diisocyanate, for example, 1,3,5-triisocyanatocyclohexane, 1,3, -Trimethylisocyanatocyclohexane, 2- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 2- (3-isocyanatopropyl) -2,6 -Di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 3- (3-isocyanatopropyl) -2,5-di (isocyanatomethyl) -bicyclo (2.2.1) heptane, 5 -(2-isocyanatoethyl) -2-isocyanatomethyl-3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl -3- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, 5- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatotop Pyr) -bicyclo (2.2.1) -heptane, 6- (2-isocyanatoethyl) -2-isocyanatomethyl-2- (3-isocyanatopropyl) -bicyclo (2.2.1) heptane, etc. And alicyclic triisocyanate.

  Examples of the araliphatic polyisocyanate include 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω′-diisocyanato-1,4-diethylbenzene, 1,3- or 1,4-bis ( 1-isocyanato-1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or a mixture thereof, for example, an araliphatic triisocyanate such as 1,3,5-triisocyanatomethylbenzene Etc.

  Examples of the aromatic polyisocyanate include m-phenylene diisocyanate, p-phenylene diisocyanate, 4,4′-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4′- or 4,4′-diphenylmethane diisocyanate or a mixture thereof. 2,4- or 2,6-tolylene diisocyanate or mixtures thereof, aromatic diisocyanates such as 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate, for example, triphenylmethane-4,4 ′, 4 '' '-Triisocyanate, aromatic triisocyanate such as 1,3,5-triisocyanatobenzene, 2,4,6-triisocyanatotoluene, for example, 4,4'-diphenylmethane-2,2', 5 , 5'-Tetri And aromatic tetraisocyanates such as cyanate.

  Examples of the polyisocyanate derivative include dimer, trimer, biuret, allophanate, adduct, carbodiimide, uretdione, uretoimine, isocyanurate, oxadiazine trione, polymethylene polyphenyl polyisocyanate (crude MDI) of the above polyisocyanate compounds. , Polymeric MDI) and crude TDI.

  Among the above, hexamethylene diisocyanate (hereinafter sometimes referred to as HMDI), isophorone diisocyanate (hereinafter sometimes referred to as IPDI), and derivatives thereof can be particularly suitably used because of industrial availability.

  The said polyisocyanate compound can be used individually or in combination of 2 or more types.

  The content of the polyisocyanate compound (PI) is preferably 200% by mass or less, more preferably in the range of 50 to 150% by mass with respect to the total solid content of the hydroxyl group-containing acrylic resin (K).

  As a curing catalyst for clear paint, known curing catalysts such as tin octylate, dibutyltin diacetate, dibutyltin di (2-ethylhexanoate), dibutyltin dilaurate, dioctyltin diacetate, dioctyltin di (2 -Ethylhexanoate), dibutyltin oxide, dioctyltin oxide, dibutyltin fatty acid salt, dibutyltin bisfatty acid salt, lead 2-ethylhexanoate, zinc octylate, zinc naphthenate, fatty acid zincs, cobalt naphthenate, octyl Organic metal compounds such as calcium acid, copper naphthenate, and tetra (2-ethylhexyl) titanate; tertiary amines can be used alone or in combination of two or more.

  Among these, an organometallic catalyst (M) is preferable. The organometallic catalyst (M) is a catalyst composed of a zinc compound (M-I) and an amidine compound (M-II). By using a zinc compound (M-I) and an amidine compound (M-II) in combination, it is excellent in curability at a low temperature and in a short time, has a good finished appearance of the coating film to be formed, and is a two-component type. It becomes possible to maintain the pot life as a paint to some extent.

  This is because a catalyst composed of a zinc compound (M-I) and an amidine compound (M-II) forms a complex structure, and the amidine compound serves as a blocking agent. After the dissociation and dissociation of the amidine compound, the catalytic ability of the zinc compound, which is excellent in low-temperature curability, becomes active, thereby achieving both low-temperature curability of the coating composition and maintaining pot life to some extent. We believe that it is possible to do that.

  Examples of the zinc compound (M-I) include a carboxylic acid zinc salt compound and an acetylacetone zinc complex. In particular, a carboxylic acid zinc salt compound can be preferably used.

  Specific examples of the carboxylic acid zinc salt compound include compounds represented by the following formula (1).

(RCO ₂ ) _n Zn (1)
(Wherein R represents an alkyl group having 1 to 30 carbon atoms, an aralkyl group having 1 to 30 carbon atoms or an alkylaryl group, and n is an integer having a value of 1 or more and 4 or less)
More specifically, examples include zinc 2-ethylhexanoate, zinc acetate, zinc octylate, zinc naphthenate, zinc octoate, zinc stearate, zinc neodecanoate, and zinc oleate.

  Zinc octylate can be particularly preferably used because of its excellent catalytic activity and easy industrial availability.

The amidine compound (M-II) is an organic compound having a structure represented by R ¹ —C (═NR ² ) —NR ³ R ⁴ . This structure has a structure in which a carbon (C) atom has one nitrogen atom as a double bond and one nitrogen atom as a single bond.

In the structural formula R ¹ —C (═NR ² ) —NR ³ R ⁴ (1),
R ¹ is a hydrogen atom, an optionally substituted organic group bonded to a carbon atom, or an amine group, and specifically, an optionally substituted hydrocarbyl group or an etherified hydroxyl group. Can be mentioned.

R ² and R ³ are independently of each other an organic group bonded to a hydrogen atom or a carbon atom, or a heterocyclic ring having a structure bonded to each other (having one or more heteroatoms, or one or more heterocycles). Having a bonded double ring with atoms).

R ⁴ is a hydrogen atom, an optionally substituted organic group bonded to a carbon atom, an optionally etherified hydroxyl group, or preferably an optionally substituted hydrocarbyl group having 8 or more carbon atoms. be able to.

When R ¹ or R ⁴ is an organic group, they may be, for example, those having 1 to 40 carbon atoms or polymer groups having a molecular weight of, for example, 500 to 50,000.

The groups represented by R ¹ , R ² , R ³ , and R ⁴ can each independently contain an alcoholic hydroxyl group as a substituent.

The amidine compound represented by the structural formula R ¹ —C (═NR ² ) —NR ³ R ⁴ (1), in which R ² and R ³ are not bonded, specifically includes:
N′-cyclohexyl-N, N-dimethylformamidine, N′-methyl-N, N-di-n-butylacetamidine, N′-octadecyl-N, N-dimethylformamidine, N′-cyclohexyl-N, N-dimethylvaleroamidine, 1-methyl-2-cyclohexyliminopyrrolidine, 3-butyl-3,4,5,6-tetrahydropyrimidine, N- (hexyliminomethyl) morpholine, N- (α- (decyliminoethyl) And ethyl) pyrrolidine, N′-decyl-N, N-dimethylformamidine, N′-dodecyl-N, N-dimethylformamidine, N′-cyclohexyl-N, N-acetamidine and the like.

Further, as the amidine compound, R ² -R ³ forms a 5- to 7-membered ring containing two nitrogen atoms in the amidine structure, and one of R ¹ -R ³ or R ¹ -R ⁴ is Amidine compounds having a structure in which a 5- to 9-membered ring is formed by one nitrogen atom and a plurality of carbon atoms in the amidine structure are also included in the amidine compound (M-II).

  Specific examples of amidine compounds having such a structure include 1,5-diazabicyclo (4.3.0) on-5-ene and 1,8-diazabicyclo (5.4.0) undec-7. Ene, 1,4-diazabicyclo (3.3.0) oct-4-ene, 2-methyl-1,5-diazabicyclo (4.3.0) on-5-ene, 2,7,8-trimethyl- 1,5-diazabicyclo (4.3.0) on-5-ene, 2-butyl-1,5-diazabicyclo (4.3.0) on-5-ene, 1,9-diazabicyclo (6.5. 0) Tridec-8-ene and the like can be mentioned.

In addition, as an amidine compound, a heterocyclic compound having a structure in which R ² and R ^{3 in} the structural formula R ¹ —C (═NR ² ) —NR ³ R ⁴ (1) are bonded, such as imidazoline and imidazole. , Tetrahydropyrimidine, dihydropyrimidine, and pyrimidine.

  Imidazole derivatives are generally represented by the following structural formula.

In the above, R ⁵ , R ⁶ , R ⁷ and R ⁸ are each independently a hydrogen atom, alkyl group or substituted alkyl group, hydroxyalkyl group, allyl group, aralkyl group, cycloalkyl group, heterocyclic ring, Ether group, thioether group, halogen, -N (R) ₂ , polyethylene polyamines, nitro groups, keto groups, ester groups, carbonamido groups, and alkyl substituents of these functional groups.

  Specific examples of the imidazole compound include N- (2-hydroxyethyl) imidazole, N- (3-aminopropyl) imidazole, 4- (hydroxymethyl) imidazole, 1- (tert-butoxycarbonyl) imidazole, imidazole- 4-propionic acid, 4-carboxyimidazole, 1-butylimidazole, 1-methylimidazole, 2-methyl-4-imidazolecarboxylic acid, 4-formylimidazole, 1- (ethoxycarbonyl) imidazole, propylene oxide and imidazole and 2- Reaction product with methylimidazole, 1-trimethylsilylimidazole, 4- (hydroxymethyl) imidazole hydrochloride, copolymer of 1-chloro-2,3-epoxypropane and imidazole, 1 (p-toluenesulfonyl) imidazole, 1, 1-carbonylbisimidazole, 1- ( -Cyanoethyl) -2-ethyl-4-methylimidazole, 2-phenyl-2-imidazoline pyromellitate, 4- (hydroxymethyl) imidazole picrate, 2-propenoic acid and 4,5-dihydro-2-nonyl- Disodium salt of 1H-imidazole-1-ethanol and 2-heptyl-4,5-dihydro-1H-imidazole-1-ethanol, 1- (cyanoethyl) -2-undecylimidazole trimellitate, 1- (2- Hydroxypropyl) imidazole formate, sodium imidazole salt, silver imidazole salt and the like.

  The above amidine compounds can be used alone or in combination of two or more.

  Specifically, in the present invention, the organometallic catalyst (M) is a zinc complex, and the complex heats, for example, 1 mol of zinc carboxylate and 2 mol of amidine compound in a solvent such as methanol. Can be manufactured.

  In the above production, a zinc complex can be prepared by holding at about 50 ° C. for about 2 hours until a transparent solution is obtained. The clear solution is filtered and dried.

  The molar ratio between the amidine compound (M-II) and the zinc compound (M-I) (number of moles of (M-II) / number of moles of (M-I)) is 1.3 to 8.0. In particular, it is preferably 1.6 to 5.0, more preferably 1.8 to 4.0.

  When the molar ratio is out of the range of 1.3 to 8.0, any of the low-temperature short-time curability, pot life, and finished appearance may be insufficient.

  The amount of the component (M) is at least one selected from the component (K); the component (L1), the component (L2), and the component (L3) from the viewpoints of low-temperature short-time curability, pot life, and finished appearance. (PI) It is preferable that it exists in the range of 0.05-5 mass% with respect to the total amount of a component, especially 0.1-4 mass%, and especially 0.3-3 mass%. If it is less than 0.05% by mass, the low-temperature short-time curability may be insufficient. Moreover, when it exceeds 5 mass%, the finished external appearance of the coating film obtained may become inadequate.

  The organometallic catalyst (M) can also be used after being dissolved in a solvent. Although the solvent is not particularly limited, for example, alcohols such as ethylene glycol, diethylene glycol, dipropylene glycol, propylene glycol, butanediol, hydrocarbons such as toluene, xylene, mineral terpenes, mineral spirits, ethyl acetate, Esters such as butyl acetate, methyl glycol acetate and cellosolve acetate, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone, glycol ethers such as ethyl 3-ethoxypropionate and 3-methoxybutyl acetate, N, N-dimethylformamide And solvents such as organic solvents of amides such as N, N-dimethylacetamide.

  In the coating composition of the present invention, a catalyst other than the organometallic catalyst (M) can be used as a catalyst, if necessary, in addition to the organometallic catalyst (M).

  The catalyst other than the organometallic catalyst (M) is not particularly limited as long as it is a conventionally known organometallic as a catalyst for polyurethane production. Specifically, stannous diacetate, stannous dioctoate, Examples thereof include organic tin catalysts such as stannous dioleate, stannous dilaurate, dibutyltin oxide, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin dichloride, and dioctyltin dilaurate. Of these, stannous dioctate and dibutyltin dilaurate are preferred.

Blocking agent (N)
Blocking agent (N) used for clear paint is β-diketone, β-keto acid ester, malonic acid ester, ketone having hydroxyl group at β-position, aldehyde having hydroxyl group at β-position and β-position And at least one compound selected from esters having a hydroxyl group.

  Specifically, for example, β-diketones: acetylacetone, benzoylacetone, dibenzoylmethane, β-keto acid esters: methyl acetoacetate, ethyl acetoacetate, ethyl benzoylacetate, malonic acid esters: ethyl malonate, β Examples include ketones having a hydroxyl group at the position: diacetone alcohol, aldehydes having a hydroxyl group at the β-position: salicylaldehyde, esters having a hydroxyl group at the β-position: methyl salicylate, and the like.

  Among the above, β-diketones are preferable because of particularly high pot life extension effect, and acetylacetone is particularly preferable.

  The amount of the blocking agent (N) is 0.7 to the total solid content of the component (K); at least one selected from the component (L1), the component (L2), and the component (L3); It is 25% by mass, preferably 1.0 to 20% by mass, and more preferably 2.0 to 15% by mass.

  The amount of the blocking agent (N) is at least one selected from the component K); the component (L1), the component (L2), and the component (L3); 0.7 based on the total solid content of the component (PI) If it is less than% by mass, the pot life extending effect may be insufficient. If it exceeds 25% by mass, the pot life extending effect may reach its peak, and the resulting coating film may have insufficient curability. .

  As the ultraviolet absorber, conventionally known ones can be used, and examples thereof include ultraviolet absorbers such as benzotriazole absorbers, triazine absorbers, salicylic acid derivative absorbers, and benzophenone absorbers.

  The content of the UV absorber in the clear paint (Z) is usually 0 to 10% by mass, particularly 0.2 to 5% by mass, more particularly 0.3 to 2% by mass, based on the total amount of resin solids. It is preferable from the viewpoint of weather resistance and yellowing resistance.

  A conventionally well-known thing can be used as said light stabilizer, For example, a hindered amine light stabilizer can be mention | raise | lifted.

  The content of the light stabilizer in the clear paint (Z) is usually 0 to 10% by mass, particularly 0.2 to 5% by mass, more particularly 0.3 to 2% by mass, based on the total amount of resin solids. It is preferable from the viewpoint of weather resistance and yellowing resistance.

  In one embodiment, the clear paint (Z) comprises 30 to 70% by mass of the hydroxyl group-containing acrylic resin (K) and the total solid content of the hydroxyl group-containing acrylic resin (K) based on the total resin solid mass of the clear paint. Of at least one resin selected from 100% by mass or less of a hydroxyl group-containing polyester resin (L1), a hydroxyl group-containing polycarbonate resin (L2), and a hydroxyl group-containing polycarbonate polyester resin (L3), and a hydroxyl group-containing acrylic resin (K) Preferably it contains 200 mass% or less polyisocyanate compound (PI) with respect to the total amount of solid content.

  In another embodiment, the clear paint (Z) comprises 30 to 70% by mass of the hydroxyl group-containing acrylic resin (K) and the total solid content of the hydroxyl group-containing acrylic resin (K) based on the total resin solid mass of the clear paint. Of at least one resin selected from 100% by mass or less of a hydroxyl group-containing polyester resin (L1), a hydroxyl group-containing polycarbonate resin (L2), and a hydroxyl group-containing polycarbonate polyester resin (L3), and a hydroxyl group-containing acrylic resin (K) Preferably, the polyisocyanate compound (PI) is 200% by mass or less based on the total solid content, and at least one selected from the (K) component, the (L1) component, the (L2) component, and the (L3) component, and (PI) 0.05-5 mass% organometallic catalyst (M), (K) component, (L1) component, ( 2) component, and (L3) contains at least one selected from the components, and the (PI) from 0.7 to 25 wt% of the block agent to total solid amount of the component (N).

  The clear paint (Z) used in the present invention may be a one-component paint or a multi-component paint such as a two-component paint. In the clear paint (Z), when a polyisocyanate compound (PI) is used as the cross-linking agent, the main component containing the base resin and the polyisocyanate compound (PI) are used from the viewpoint of storage stability. It is preferable to use a two-component paint composed of a cross-linking agent contained and to mix both of them immediately before use.

  The coating method of the clear paint (Z) is not particularly limited, and for example, the wet coating film can be formed by a coating method such as air spray coating, airless spray coating, rotary atomization coating, or curtain coat coating. In these coating methods, electrostatic application may optionally be performed. Of these, air spray coating is particularly preferred. The film thickness of the clear paint (Z) is usually 10 to 50 μm, preferably 20 to 45 μm, as a cured film thickness.

  When air spray coating, airless spray coating, and rotary atomization coating are performed, the viscosity of the clear coating (Z) is adjusted to a viscosity range suitable for the coating, usually Ford Cup #No. In a 4-viscosity meter, it is preferable to adjust appropriately using a solvent such as an organic solvent so that the viscosity is within a range of about 15 to 60 seconds at 20 ° C.

Step (4)
A multi-layer coating film composed of three layers of the first colored coating film, the second colored coating film, and the clear coating film formed as described above is a conventional coating film baking means such as hot air. Heating can be performed by heating, infrared heating, high frequency heating or the like.

  The heating and holding temperature (keep temperature) is excellent in curability at a low temperature, and therefore it is suitable to be in the range of 60 to 140 ° C., particularly 70 to 120 ° C. The heating and holding time (keep time) is suitably in the range of 10 to 50 minutes, particularly 20 to 40 minutes.

  Optionally, before performing the bake hardening, it may be set at room temperature for about 1 to 60 minutes and / or preheated at a temperature of 40 to 80 ° C. for about 1 to 60 minutes.

  The multi-layer coating film forming method of the present invention is capable of forming a coating film having excellent chipping resistance, adhesion, finish, weather resistance and gasohol resistance against a metal member and a plastic member. it can.

  INDUSTRIAL APPLICABILITY The present invention can be suitably used as a method for forming a multilayer coating film for all industrial products containing a metal material and a plastic material. Especially, it can use especially suitably as a multilayer coating-film formation method of a motor vehicle.

  According to the multilayer coating film forming method of the present invention, a coating film having excellent chipping resistance, adhesion, finish, weather resistance, and gasohol resistance is formed on both a metal member and a plastic member. The reason why this can be done is not clear, but can be estimated as follows. In the method for forming a multilayer coating film of the present invention, since the aqueous first colored paint contains a specific aqueous polyurethane resin, it has excellent adhesion to both a metal member and a plastic member. This is presumed to show excellent chipping resistance and gasohol resistance. Further, since the aqueous first colored paint contains block polyisocyanate, it is excellent in curability at low temperature and in a short time. Moreover, since the crosslinking density of a coating film becomes high by this outstanding sclerosis | hardenability, it is excellent in water resistance and adhesiveness. Furthermore, the excellent curability brings about the effect of developing the viscosity of the first colored coating film, suppresses the layering with the second colored coating film during coating, and suppresses the deterioration of the finished appearance of the multilayer coating film due to the mixing layer. be able to. Furthermore, since the light transmittance of the obtained multilayer coating film is low, deterioration of the coating film due to light is suppressed, and thus it has excellent chipping resistance, adhesion, finish, weather resistance and gasohol resistance. It is presumed that a coating film can be formed.

  Due to these synergistic effects, the multi-layer coating film forming method of the present invention has excellent chipping resistance, adhesion, finish, weather resistance and gasohol resistance for both metal members and plastic members. It is thought that the multilayer coating film which has can be formed. Furthermore, in the multilayer coating film formed by the multilayer coating film forming method of the present invention, the pot life of the clear coating material can be maintained at an appropriate length.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples. However, the present invention is not limited to only these examples. “Part” and “%” are based on mass. Moreover, the film thickness of a coating film is based on a cured coating film.

Production of water-based first colored paint (X)
Production and production example 1 of non-chlorine polyolefin resin (A)
A mixture comprising 500 parts of a maleated polypropylene resin having a weight average molecular weight of 80,000 (chlorination rate 22%, maleic acid modification amount 2.0%, acid value 30 mg KOH / g), n-heptane 150 parts and N-methylpyrrolidone 50 parts Heated to 50 ° C., charged with 12 parts of dimethylethanolamine and 5 parts of “Neugen EA-140” (nonionic surfactant, trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) and stirred at the same temperature for 1 hour. Thereafter, 2000 parts of deionized water was gradually added and further stirred for 1 hour.
Next, the pressure was reduced at a temperature of 70 ° C., and a total of 600 parts of n-heptane and water were distilled off to obtain a non-chlorinated polyolefin resin dispersion (A-1) having a solid content of 23.6%. .

Production Example 2
In a four-necked flask equipped with a stirrer, condenser, thermometer and dropping funnel, maleic anhydride-grafted polypropylene (modified with a maleic acid addition amount of 4% by mass relative to polypropylene obtained using a metallocene catalyst) Then, 100 g of melting point 80 ° C., Mw about 150,000, Mw / Mn about 2.5) is heated and melted at 140 ° C. to obtain polyoxyethylene stearyl ether (“New Coal 1820”, one-terminal hydroxyl group-containing polyoxyethylene compound, Japan (Emulsifier Co., Ltd.) (15 g) was added and the reaction was carried out at 140 ° C. for 4 hours with stirring. After the reaction, the mixture was cooled to 90 ° C., filtered with deionized water, and a non-chlorine polyolefin resin dispersion (A-2) having a solid content of 30% was obtained.

Production and production example 3 of aqueous polyurethane resin (B)
In a reaction vessel equipped with a thermometer, a stirrer and a reflux condenser, 211.9 parts of polytetramethylene glycol (number average molecular weight 1000), 11.5 parts of α, α-dimethylolpropionic acid, 6.9 parts of trimethylolpropane, After charging 112.2 parts of isophorone diisocyanate and 298.5 parts of methyl ethyl ketone, the reaction system was replaced with nitrogen gas, and then reacted at 80 ° C. with stirring to obtain an NCO-terminated urethane prepolymer having a free isocyanate group content of 3.2%. . The obtained methyl ethyl ketone solution was cooled to 40 ° C., 493.2 g of deionized water containing 5.2 parts of triethylamine was added and emulsified, and then 159.2 parts of 5% ethylenediamine aqueous solution was added thereto, followed by stirring for 60 minutes, and then methyl ethyl ketone. Is distilled under reduced pressure, the concentration is adjusted with deionized water, the solid content is 35%, the time required for film formation at a temperature of 20 ° C. for 15 minutes, an aqueous polyurethane having an acid value of 14 mg KOH / g and an average particle size of 120 nm A resin dispersion (B-1) was obtained.

Production Examples 4 to 13
In Production Example 3, operations were carried out in the same manner as in Production Example 3 except that the composition was as shown in Table 1, to obtain aqueous polyurethane resin dispersions (B-2) to (B-11).

In addition, the compounding of Table 1 is a solid content display, and (Note 1) in Table 1 is as follows.
(Note 1) Manufacture of polyester polyol A 67 parts of polyethylene glycol (number average molecular weight 300), 49 parts of sodium salt of 5-sulfoisophthalic acid dimethyl ester and 0.2 part of dibutyltin oxide are charged into a reaction vessel under a reduced pressure of 5 mmHg. The mixture was heated to 190 ° C. and subjected to transesterification for 6 hours while distilling off methanol, having an average of 5 sodium sulfonate groups in one molecule, having a hydroxyl value of 29.6 mgKOH / g and a number average molecular weight of 3700. Polyester polyol A was obtained.

Production Example 14 of Block Polyisocyanate Compound (C) Having Nonionic Hydrophilic Group 14
In a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, nitrogen inlet tube, dropping device and removal solvent simple trap, “Sumidule N-3300” (trade name, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene) Isocyanurate structure-containing polyisocyanate derived from diisocyanate, solid content about 100%, isocyanate group content 21.8%) 1610 parts, “Uniox M-550” (manufactured by NOF Corporation, polyethylene glycol monomethyl ether, average molecular weight about 550) ) 275 parts and 0.9 parts of 2,6-di-t-butyl-4-methylphenol were charged, mixed well, and heated at 130 ° C. for 3 hours under a nitrogen stream. Next, 550 parts of ethyl acetate and 1150 parts of diisopropyl malonate were charged, and 14 parts of a 28% methanol solution of sodium methoxide was added while stirring under a nitrogen stream, followed by stirring at 65 ° C. for 8 hours. The amount of isocyanate in the obtained resin solution was about 0.1 mol / kg. To this, 3110 parts of 4-methyl-2-pentanol was added, the solvent was distilled off under reduced pressure conditions for 3 hours while maintaining the temperature of the system at 80 to 85 ° C., and the block polyisocyanate compound solution (C-1 ) 4920 parts were obtained. The removal solvent simple trap contained 585 parts of isopropanol. The resulting block polyisocyanate compound solution (C-1) had a solid content concentration of about 60%.

Production Example 15
In a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, nitrogen inlet tube, dropping device and removal solvent simple trap, “Sumidule N-3300” (trade name, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene) Isocyanurate structure-containing polyisocyanate derived from diisocyanate, solid content about 100%, isocyanate group content 21.8%) 1610 parts, “Uniox M-550” (manufactured by NOF Corporation, polyethylene glycol monomethyl ether, average molecular weight about 550) ) 275 parts and 0.9 parts of 2,6-di-t-butyl-4-methylphenol were charged, mixed well, and heated at 130 ° C. for 3 hours under a nitrogen stream. Next, 550 parts of ethyl acetate and 1150 parts of diisopropyl malonate were charged, and 14 parts of a 28% methanol solution of sodium methoxide was added while stirring under a nitrogen stream, followed by stirring at 65 ° C. for 8 hours. The amount of isocyanate in the obtained resin solution was about 0.1 mol / kg. The resulting block polyisocyanate compound solution (C-2) had a solid concentration of about 60%.

Production Example 16
Into a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, nitrogen inlet tube, dropping device and removal solvent simple trap, 1610 parts of "Sumidur N-3300" and 236 parts of hydroxypivalic acid were charged and stirred. The mixture was mixed well and heated at 130 ° C. for 3 hours under a nitrogen stream. Next, 550 parts of ethyl acetate and 930 parts of diisopropyl malonate were charged, and 14 parts of a 28% methanol solution of sodium methoxide was added while stirring under a nitrogen stream, followed by stirring at 65 ° C. for 8 hours. The amount of isocyanate in the obtained resin solution was about 0.1 mol / kg. To this, 2530 parts of 4-methyl-2-pentanol was added, and the solvent was distilled off under reduced pressure conditions for 3 hours while maintaining the temperature of the system at 80 to 85 ° C. to obtain a block polyisocyanate compound solution (C-3 ) 4450 parts were obtained. The removal solvent simple trap contained 475 parts of isopropanol. The resulting block polyisocyanate compound solution (C-3) had a solid content concentration of about 60%.

Production Example 17
In a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, nitrogen inlet tube, dropping device and removal solvent simple trap, “Sumidule N-3300” (trade name, manufactured by Sumika Bayer Urethane Co., Ltd., hexamethylene) Diisocyanate-derived isocyanurate structure-containing polyisocyanate, solid content of about 100%, isocyanate group content of 21.8%) 480 parts, ethyl acetate 150 parts and diisopropyl malonate 365 parts, while stirring under a nitrogen stream, sodium 4 parts of 28% methanol solution of methoxide was added and stirred at 65 ° C. for 8 hours. The amount of isocyanate in the obtained resin solution was 0.07 mol / Kg. To this was added 870 parts of 4-methyl-2-pentanol, the solvent was distilled off under reduced pressure for 3 hours while maintaining the temperature of the system at 80 to 85 ° C., and 4-methyl-2-pentanol was further removed. 120 parts were added to obtain 1400 parts of a blocked polyisocyanate compound solution (C-4). The removal solvent simple trap contained 183 parts of isopropanol. The resulting block polyisocyanate compound solution (C-4) had a solid concentration of about 60%.

  In addition, (C-1) and (C-2) are block polyisocyanate compound solutions used in examples described later, and (C-3) and (C-4) are used in comparative examples described later. It is a block polyisocyanate compound solution having no nonionic hydrophilic group.

Production and production example 18 of hydroxyl group-containing acrylic resin
A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen inlet tube and dropping device was charged with 35 parts of propylene glycol monopropyl ether, heated to 85 ° C., then 30 parts of methyl methacrylate, 2-ethylhexyl acrylate 20 Parts, n-butyl acrylate 29 parts, 2-hydroxyethyl acrylate 15 parts, acrylic acid 6 parts, propylene glycol monopropyl ether 15 parts and 2,2′-azobis (2,4-dimethylvaleronitrile) 2.3 parts. The mixture was added dropwise over 4 hours and aged for 1 hour after completion of the addition. Thereafter, a mixture of 10 parts of propylene glycol monopropyl ether and 1 part of 2,2′-azobis (2,4-dimethylvaleronitrile) was added dropwise over 1 hour, followed by aging for 1 hour after completion of the addition. Further, 7.4 parts of diethanolamine was added to obtain a hydroxyl group-containing acrylic resin solution (E-1) having a solid content of 55%. The obtained hydroxyl group-containing acrylic resin had an acid value of 47 mgKOH / g and a hydroxyl value of 72 mgKOH / g.

Production Example 19 of Hydroxyl-Containing Polyester Resin 19
In a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser and water separator, 192 parts of adipic acid, 307 parts of hexahydrophthalic anhydride, 439 parts of 2-butyl-2-ethyl-1,3-propanediol , 88.7 parts of 1,6-hexanediol and 36.0 parts of trimethylolpropane were heated from 160 ° C. to 230 ° C. over 3 hours, and then condensed water was distilled off with a water separator. The reaction was continued at a temperature of 0 ° C. until the desired acid value was reached. To this reaction product, 20.2 parts of trimellitic anhydride was added, subjected to an addition reaction at 170 ° C. for 30 minutes, cooled to 50 ° C. or lower, neutralized with 2- (dimethylamino) ethanol, By gradually adding deionized water, a hydroxyl group-containing polyester resin aqueous dispersion (F-1) having a solid content concentration of 45% was obtained. The resulting hydroxyl group-containing polyester resin had an acid value of 20 mgKOH / g, a hydroxyl value of 60 mgKOH / g, and a number average molecular weight of 1,700.

Production Example 20 of First Colored Paint (X) 20
Non-chlorinated polyolefin resin dispersion (A-1) 35 parts (solid content), aqueous polyurethane resin dispersion (B-1) 20 parts (solid content), block polyisocyanate compound solution having a nonionic hydrophilic group ( C-1) 20 parts (solid content), 10 parts (solid content) of the hydroxyl group-containing acrylic resin solution (E-1), 15 parts (solid content) of the hydroxyl group-containing polyester resin (F-1), conductive pigment ( D-1) 5 parts (“Ketjen Black EC600J” manufactured by Lion Akzo, trade name, conductive carbon black pigment) and 100 parts “JR-806” (trade name, titanium white) It mix | blended according to the method, mixed and disperse | distributed, and it diluted with deionized water so that it might become 20% of solid content, and obtained the water-based 1st colored coating material (X-1).

Production Examples 21 to 42
In Production Example 20, operations were carried out in the same manner as in Production Example 20 except that the composition was as shown in Table 2, to obtain water-based first colored paints (X-2) to (X-23).

In addition, the mixing | blending of Table 2 is a solid content display, (Note 2) in Table 2 is as follows.
(Note 2) Aqueous chlorinated polyolefin (A-3) (aqueous dispersion of maleic acid-modified chlorinated polypropylene having an acid value of 35 mgKOH / g and 22% chlorine content by modification with maleic acid)

Manufacture of clear paint (Z)
Production and production examples 43-50 of hydroxyl group-containing acrylic resin (K)
31 parts of ethoxyethyl propionate was charged into a four-necked flask equipped with a stirrer, a thermometer, a condenser, and a nitrogen gas inlet, and the temperature was raised to 155 ° C. under nitrogen gas flow. After reaching 155 ° C., the flow of nitrogen gas was stopped, and a monomer mixture composed of a monomer and a polymerization initiator shown in Table 3 below was dropped over 4 hours. Next, after aging for 2 hours while ventilating nitrogen gas at 155 ° C., the mixture was cooled to 100 ° C. and diluted with 32.5 parts of butyl acetate, whereby a hydroxyl group-containing acrylic resin (K-1) having a solid content of 60% was obtained. To (K-8). The mass solid content concentration (%) of the obtained hydroxyl group-containing acrylic resin and the special values of the resin are shown in Table 3 below.

Production Production Example 51 of Hydroxyl-Containing Polycarbonate Polyester Resin (L3) 51
In a reactor equipped with a thermometer, thermostat, stirrer and heating device, 270 parts of UM-90 (trade name, manufactured by Ube Industries, polycarbonate ester), 136.8 parts of ε-caprolactone, dibutyltin oxide The amount of the polycarbonate polyester resin contained was such that the number average molecular weight was about 1700), and the temperature was raised to 170 ° C. while stirring. The reaction was continued at 170 ° C., and it was confirmed that the heating residue was 98.5% or more, followed by cooling and discharging to obtain a hydroxyl group-containing polycarbonate polyester resin (L3-1) solution. The number average molecular weight of the obtained hydroxyl group-containing polycarbonate polyester resin (L3-1) was 1650.

Production Example 52
In a reactor equipped with a thermometer, thermostat, stirrer and heating device, 270 parts of UM-90 (trade name, manufactured by Ube Industries, polycarbonate ester), 136.8 parts of ε-caprolactone, dibutyltin oxide The amount of the polycarbonate-polyester resin contained was such that the number average molecular weight was about 2200), and the temperature was raised to 170 ° C. while stirring. The reaction was continued at 170 ° C., and it was confirmed that the heating residue was 98.5% or more, followed by cooling and discharging to obtain a hydroxyl group-containing polycarbonate polyester resin (L3-2) solution. The number average molecular weight of the obtained hydroxyl group-containing polycarbonate polyester resin (L3-2) was 2200.

Production Example 53
In a reactor equipped with a thermometer, thermostat, stirrer and heating device, 270 parts of UM-90 (trade name, manufactured by Ube Industries, polycarbonate ester), 136.8 parts of ε-caprolactone, dibutyltin oxide The amount of the polycarbonate polycarbonate resin contained was such that the number average molecular weight was about 3000), and the temperature was raised to 170 ° C. while stirring. The reaction was continued at 170 ° C., and it was confirmed that the heating residue was 98.5% or more, followed by cooling and discharging to obtain a hydroxyl group-containing polycarbonate polyester resin (L3-3) solution. The number average molecular weight of the obtained hydroxyl group-containing polycarbonate polyester resin (L3-3) was 2900.

Preparation and production examples of clear paint (Z) 54-79
Using the raw materials shown in Table 5, the mixture shown in Table 5 below was stirred and mixed using a blade-type stirrer. Next, butyl acetate was added to the mixture, and Ford Cup #No. 4 was adjusted to a viscosity of 25 seconds at 20 ° C. to obtain clear paints (Z-1) to (Z-14). In addition, the mixing | blending of the clear coating material (Z) shown in Table 5 is solid content mass ratio of each component.

  The hydroxyl group-containing polyester resin (L1-1) and the hydroxyl group-containing polycarbonate resin (L2-1) in Table 5 have the following meanings.

  Hydroxyl-containing polyester resin (L1-1): “Placcel 305” trade name, manufactured by Daicel Chemical Industries, Ltd. Number average molecular weight 550.

  Hydroxyl group-containing polycarbonate resin (L2-1): “UM-90” trade name, manufactured by Ube Industries, Ltd., diol components are 1,4-cyclohexanedimethanol and 1,6-hexanediol, 1,4-cyclohexanedimethanol Mass / 1,6-hexanediol mass = 1/1. Number average molecular weight 900.

  Details of the organometallic catalyst (M) in Table 5 are as shown in Table 4 below.

* 1 Nikka Octics Zinc Nippon Chemical Industry Co., Ltd., zinc content 8%
* 2 Zinc naphthenate manufactured by Tokyo Chemical Industry Co., Ltd., zinc content 10.1%
* 3 Zinc acetylacetone Showa Chemical Co., Ltd., zinc content 25%
* 4 Zinc dibenzoate Wako Pure Chemical Industries, zinc content 21.3%
* 5 Zinc laurate Wako Pure Chemical Industries, zinc content 14.1%
* 6 Nikka Octix Tin, Nippon Chemical Industry Co., Ltd., tin content 28%
* 7 K-KAT348 King Industries, bismuth content 25%
* 8 DBU Diazabicycloundecene The polyisocyanate compound (PI) in Table 5 has the following meaning.

  Polyisocyanate compound (PI): “Sumijour N3300” trade name, manufactured by Sumika Bayer Urethane Co., Ltd., isocyanurate of hexamethylene diisocyanate, solid content 100%, isocyanate group content 21.8%

I-1. As a metal member for producing a test coated plate, a zinc phosphate-treated cold rolled steel sheet (450 mm × 300 mm × 0.8 mm), a thermosetting epoxy resin-based cationic electrodeposition coating composition (trade name “Electron GT-10”, Kansai Paint Co., Ltd.) was electrodeposited to a film thickness of 20 μm and cured by heating at 170 ° C. for 30 minutes.

  As a plastic member, “TSOP-1 (TC-6)” (trade name, manufactured by Nippon Polychem, 350 mm × 10 mm × 2 mm) was prepared.

  And the surface of the metal member and the plastic member was degreased by wiping with gauze containing petroleum benzine. A steel plate and a polypropylene plate obtained as described above were arranged adjacent to each other to obtain a test plate.

  The first colored paints (X-1) to (X-23) prepared above are spray-coated on the test plate to a dry film thickness of 10 μm, set at room temperature for 6 minutes, and then used as a colored base paint. , “WBC-713T # 1F7” (trade name, manufactured by Kansai Paint Co., Ltd., acrylic / melamine resin water-based base coat paint, silver paint color, “6 (Y-1)” in Tables 6 and 7) Electrostatic coating was applied to a thickness of 15 μm. Next, the clear paints (Z-1) to (Z-26) produced above are electrostatically coated so as to have a dry film thickness of 30 μm, left at room temperature for 5 minutes, and then in an oven at 95 ° C. for 30 minutes. The test coating plate in which the multilayer coating film was formed by heating was obtained. Various coating film performance tests described below were performed on the multilayer coating film (Tables 6 and 7).

I-2. Coating film performance test finish: The finish was evaluated by the following smoothness and sharpness.

Smoothness: Evaluated using a W1 value measured by “Wave Scan DOI” (trade name, manufactured by BYK Gardner). It shows that the smoothness of a coating surface is so high that W1 value is small.
S: W1 value is less than 10.0 A: W1 value is 10.0-20.0
C: W1 value exceeding 20.0.

Vividness: Evaluated using W4 value measured by “Wave Scan DOI” (trade name, manufactured by BYK Gardner). The smaller the W4 value, the higher the clearness of the paint surface.
S: W4 value is less than 10.0 A: W4 value is 10.0-20.0
C: W4 value exceeding 20.0.

Chipping resistance: A test coating plate is placed on a specimen holder of a stepping stone testing machine (trade name “QGR GRvelometer” (manufactured by Q Panel Co., Ltd.), and at −20 ° C., 30 cm away from the test coating plate 100 g of granite crushed stone with a particle size of 6 was collided with the test coating plate at an angle of 90 ° with compressed air of 480 to 520 kPa, and the resulting test coating plate was washed with water and dried. Nichiban Co., Ltd.) was attached, and the tape was peeled off and evaluated based on the area where the electrodeposition surface and the base member were exposed (abbreviated as peeled area).
S: The ratio of the peeled area to the test coated plate area is less than 5%. A: The ratio of the peeled area to the test coated board area is less than 5 to 10%.

Water-resistant adhesion: Immerse the test coating plate in warm water at 40 ° C for 240 hours, pull it up and dry it at 20 ° C for 12 hours, then cut the multilayer coating film of the test coating plate into a grid shape with a cutter so as to reach the substrate, Make 100 2mm x 2mm gobangs. Subsequently, an adhesive cellophane tape was attached to the surface, and the remaining state of the goby eye coating after the tape was rapidly peeled off at 20 ° C. was examined, and the water resistance was evaluated according to the following criteria.
S: 100 Gobang eye coats remain, and no small flickering of the paint film occurs at the edge of the cutter cut A: 100 Gobang eye coats remain, but the paint coat is small at the edge of the cutter cut B: Spots are generated B: 90 to 99 pieces of Gobang eye coat remain C: The number of remaining Goban eye coats is 89 or less.

Gasohol resistance: This will be explained for each member.
In the case of plastic members: Each test coated plate is immersed in a test solution of gasoline / methanol = 90/10 weight ratio at 20 ° C., and the coated surface state after 30 minutes of bulging and peeling is observed and evaluated according to the following criteria. did.
S: No abnormality at all
A: blistering less than 3 mm, peeling,
B: 3-5 mm or less blistering, peeling,
C: Puff and peeling exceeding 5 mm.
For metal parts: Each test coated plate is immersed in a gasoline / methanol = 90/10 weight ratio test solution at 40 ° C., and after 60 minutes have passed, the state of blistering and peeling is observed. Evaluation based on the criteria.

Weather resistance: Specimen wetting cycle for each test coated plate coated on a metal member using “Super Xenon Weather Meter” (manufactured by Suga Test Instruments Co., Ltd., weather resistance tester) according to JIS K 5600-7-7 : The accelerated weather resistance test was conducted under the conditions of 18 minutes / 2 hours and black panel temperature of 61 to 65 ° C. Next, when the irradiation time of the lamp reaches 1,000 hours, 2,000 hours and 3,000 hours, the multilayer coating film of the test plate is cut into a lattice shape with a cutter so as to reach the substrate, 100 2mm x 2mm gobang eyes were made. Next, an adhesive cellophane tape was attached to the surface, and the remaining state of the goby eye coating after the tape was peeled off rapidly was examined.
S: 100 Gobang eye coats remain, and no small flickering of the paint film occurs at the edge of the cutter cut A: 100 Gobang eye coats remain, but the paint coat is small at the edge of the cutter cut Spots are generated C: The remaining number of goby eye coatings is 99 or less.

Pot life (pot life): The viscosity at 20 ° C. after 6 hours of each clear paint was measured with Ford Cup #No. 4 was measured. The pot life after preparation of the coating composition was measured and evaluated according to the following criteria.
S: 35 seconds or less A: 36 to 40 seconds C: Gelation −: Not measured

II-1. As a metal member for producing a test coated plate, a zinc phosphate-treated cold rolled steel sheet (450 mm × 300 mm × 0.8 mm), a thermosetting epoxy resin-based cationic electrodeposition coating composition (trade name “Electron GT-10”, Kansai Paint Co., Ltd.) was electrodeposited to a film thickness of 20 μm and cured by heating at 170 ° C. for 30 minutes.

  As a plastic member, “TSOP-1 (TC-6)” (trade name, manufactured by Nippon Polychem, 350 mm × 10 mm × 2 mm) was prepared.

  And the surface of the metal member and the plastic member was degreased by wiping with gauze containing petroleum benzine. A steel plate and a polypropylene plate obtained as described above were arranged adjacent to each other to obtain a test plate.

  The first colored paint (X-1) prepared above is spray-coated on the test plate so as to have a dry film thickness of 10 μm, set at room temperature for 6 minutes, and then the second colored paint ( Y-1) was electrostatically coated to a dry film thickness of 15 μm. Next, the clear paint (Z-15), (Z-17), (Z-19), (Z-24), (Z-25) or (Z-26) prepared above is dried to a thickness of 30 μm. The coating was electrostatically coated and allowed to stand at room temperature for 5 minutes, and then heated in an oven at 75 ° C. for 30 minutes to obtain a test coating plate on which a multilayer coating film was formed. Various coating film performance tests described below were conducted on the multilayer coating film (Table 8).

II-2. Coating film performance test The same operations and the same evaluations as described in the item "I-2. Coating film performance test" were performed.

Claims (8)

(1) A step of forming an uncured first colored coating film by applying an aqueous first colored paint (X) on an object containing a metal material and a plastic material;
(2) A step of coating the aqueous second colored paint (Y) on the uncured first colored coating film obtained in the step (1) to form an uncured second colored coating film,
(3) A step of coating the clear paint (Z) on the uncured second colored coating film obtained in the step (2) to form an uncured clear coating film, and (4) Steps (1) to (4) A step of simultaneously curing these three coating films by heating the uncured first colored coating film, the uncured second colored coating film and the uncured clear coating film formed in (3),
A multilayer coating film forming method for sequentially performing,
The aqueous first colored paint (X) is a non-chlorinated polyolefin resin (A), an acid value of 1 to 30 mg KOH / g, and an aqueous polyurethane having a time of film formation at a temperature of 20 ° C. for 5 to 20 minutes. Containing a resin (B), a blocked polyisocyanate compound (C) having a nonionic hydrophilic group, and a conductive pigment (D);
A multilayer coating film, wherein an average light transmittance at a wavelength of 360 to 420 nm of a cured coating film having a thickness of 5 μm obtained by applying and curing the aqueous first colored paint (X) is less than 1% Forming method. The clear paint (Z)
Hydroxyl-containing acrylic resin (K) having a hydroxyl value of 140 to 210 mg KOH / g, a weight average molecular weight of 5000 to 18000, and a glass transition temperature of 25 to 20 ° C.
The multilayer coating-film formation method of Claim 1 containing. The clear paint (Z)
At least one selected from a hydroxyl group-containing polyester resin (L1) having a number average molecular weight of 500 to 2500, a hydroxyl group-containing polycarbonate resin (L2) having a number average molecular weight of 500 to 2500, and a hydroxyl group-containing polycarbonate polyester resin (L3) having a number average molecular weight of 500 to 2500. The method for forming a multilayer coating film according to claim 2, comprising a seed resin. The clear paint (Z)
30 to 70% by mass of a hydroxyl group-containing acrylic resin (K) based on the total resin solid mass of the clear paint,
100% by mass or less of a hydroxyl group-containing polyester resin (L1), a hydroxyl group-containing polycarbonate resin (L2) and a hydroxyl group-containing polycarbonate polyester resin (L3) based on the total solid content of the hydroxyl group-containing acrylic resin (K). Resin,
And the solid content total amount of the hydroxyl-containing acrylic resin (K), 2 00 wt% of the polyisocyanate compound (PI) and a multilayer coating film forming method according to claim 3 containing. Block polyisocyanate compound (C) having a nonionic hydrophilic group,
Block isocyanate group represented by the following general formula (I)

[In the formula (I), R ¹ , R ² , R ⁴ and R ⁵ independently represent a hydrocarbon group having 1 to 12 carbon atoms, and R ³ is a straight chain having 1 to 12 carbon atoms or Represents a branched alkylene group. ],
Blocked isocyanate group represented by the following general formula (II)

[In formula (II), R ² , R ³ , R ⁴ and R ⁵ are the same as above. ]
And a blocked isocyanate group represented by the following general formula (III)

Wherein ^{(III), R 2, R} 3, R 4 and ^{R 5} are as defined above, ^{R 6} represents a hydrocarbon group having 1 to 12 carbon atoms. ]
The method for forming a multilayer coating film according to any one of claims 1 to 4, which is a block polyisocyanate compound having at least one type of blocked isocyanate group selected from the group consisting of: The clear paint (Z)
An organometallic catalyst (M) comprising a zinc compound and an amidine compound, and β-diketones, β-keto acid esters, malonic acid esters, ketones having a hydroxyl group at the β-position, aldehydes having a hydroxyl group at the β-position, and It further contains at least one blocking agent (N) selected from esters having a hydroxyl group at the β-position,
The amount of the organometallic catalyst (M) is at least one selected from the component (K); the component (L1), the component (L2), and the component (L3); 5% by mass,
The method for forming a multilayer coating film according to claim 3, wherein: The amount of the blocking agent (N) is at least one selected from the component (K); the component (L1), the component (L2), and the component (L3); 0.7 to the total solid content of the component (PI) 25% by mass
The method for forming a multilayer coating film according to claim 6, wherein:   The multi-layer coating film forming method according to any one of claims 1 to 7, wherein the object to be coated containing the metal material and the plastic material is an object to be coated by assembling the metal material and the plastic material.