JP5933205B2 - Copolymer, aqueous coating composition containing the copolymer, and method for forming a multilayer coating film - Google Patents

Description

  The present invention relates to a copolymer and a viscosity modifier comprising the copolymer. More specifically, the present invention relates to a copolymer that can be suitably used as a viscosity adjusting agent capable of developing a viscosity in an aqueous coating composition containing a coating additive, particularly a surfactant. The present invention also relates to an aqueous coating composition containing the copolymer and a method for forming a multilayer coating film using the aqueous coating composition.

  For coating an object such as an automobile that requires an excellent appearance, generally, a method of applying the paint by atomizing the paint is used from the viewpoint of the appearance of the formed coating film and production efficiency. Specific examples of such a coating method include spray coating and rotary atomization coating.

  In the case of coating by atomizing the paint, the paint used is generally low in viscosity when spraying, rotating atomization, etc., and the smaller paint particles are formed, which makes smoothness smooth. It is preferable because an excellent coating film is formed. On the other hand, after the paint has been applied to the object to be coated, the viscosity of the paint is high, and it is difficult for the paint layer to be mixed with the paint to be applied on the upper layer, and a coating film with excellent sharpness is formed. ,preferable. Further, when the paint contains a bright pigment such as an aluminum pigment, if the paint viscosity is high after the paint is applied to an object, the bright pigment in the paint is difficult to move and the orientation is not easily disturbed. Therefore, it is possible to form a coating film excellent in glitter. Note that a coating film with excellent glitter generally has a remarkable change in brightness due to the observation angle when the coating film is observed at different angles, and the glitter pigment is relatively contained in the coating film. A coating film that exists uniformly and has almost no metallic unevenness. Further, as described above, the fact that the change in brightness depending on the observation angle is remarkable is generally said to have high flip-flop properties.

  For the reasons described above, the paint is excellent in that the viscosity is low when the shear rate is large as in atomization and the viscosity is high when the shear rate is low as in coating. It is preferable because a coating film having an appearance can be formed. That is, it is preferable that the coating material has a viscosity that decreases as the shear rate increases.

  As a means for producing a paint whose viscosity decreases as the shear rate increases, a method of blending an associative thickener in the paint can be mentioned. The associative thickener generally has a hydrophilic part and a hydrophobic part in one molecule, and in an aqueous medium, the hydrophobic part is adsorbed on the surface of the pigment or emulsion particles in the paint, It is a thickener that effectively forms a thickening action by forming a network structure when hydrophobic portions are associated with each other.

  The associative thickener usually forms a network structure by hydrophobic interaction and develops viscosity. On the other hand, since the hydrophobic interaction has a relatively weak binding force, when a large shear force is applied, the network structure is broken and the viscosity is lowered. For this reason, the coating material containing the said association type | mold thickener has a viscosity characteristic that a viscosity falls with the increase in a shear rate.

  Recently, water-based paints have been developed from the viewpoint of suppressing environmental pollution caused by volatilization of organic solvents.

  The aqueous paint generally contains a surfactant in order to disperse a hydrophobic resin component in water.

  However, in the aqueous paint containing the surfactant, when the association type thickener is used, the viscosity due to the association type thickener becomes difficult to develop, and the formed coating film has high clarity and glitter. May be reduced, and was considered a problem. Specifically, since the viscosity when the water-based paint is applied to an object to be coated is low, a mixed layer is formed with the paint to be coated on the upper layer, and the clarity of the formed coating film is reduced. Or when the water-based paint contains a glitter pigment, the glitter pigment in the paint moves after the paint is applied, the orientation of the glitter pigment becomes irregular, and the flip-flop properties are reduced. In some cases, metallic unevenness may occur. On the other hand, when the viscosity at the time of application is increased by increasing the content of the associative thickener in the water-based paint, the viscosity when the shear rate is high is increased, and the paint is atomized. Since the coating particles at the time become large, the smoothness of the formed coating film may be inferior.

  For example, Patent Document 1 discloses a viscosity control agent comprising a hydrophobic part and a hydrophilic part obtained by hydrophobizing a hydrophilic polymer and / or obtained by hydrophobizing a hydrophobic polymer. In addition, the concentration dependency of the viscosity of the aqueous dispersion can be reduced, and further, the water-based paint using the viscosity control agent exhibits a stable flow property regardless of changes in the coating conditions, particularly temperature and humidity conditions. It is described that a coating film having a stable and excellent finish can be obtained. However, in some cases, the viscosity control agent has insufficient viscosity. In particular, when the viscosity control agent is used in a paint containing a surfactant, a sufficient viscosity cannot be obtained, and the sharpness and flip-flop properties of the formed coating film are reduced, or metallic unevenness is caused. There was a tendency to occur.

  Patent Document 2 discloses associative thickening in which one molecule of alkenyl succinic anhydride or alkyl succinic anhydride is added per amino group to polyethylene glycol having at least two amino groups at the end of the molecule. In order to improve the workability of the solution adjustment and facilitate the quality control of the product, the viscosity of the agent and the water-based paint is not increased. It is described that it is excellent as an agent. However, the associative thickener sometimes has insufficient viscosity. In particular, when the associative thickener is used in a paint containing a surfactant, a sufficient viscosity cannot be obtained, and the sharpness and flip-flop property of the formed coating film are reduced, or metallic There was a tendency for unevenness to occur.

  Patent Document 3 describes that a urethane-based thickener having a specific structure is a thickening and viscosity adjusting agent excellent in thickening and thixotropic properties. The thixotropic property is the above-described viscosity characteristic in which the viscosity decreases as the shear rate increases. However, the urethane-based thickener sometimes has insufficient viscosity. In particular, when the urethane-based thickener is used in a paint containing a surfactant, a sufficient viscosity cannot be obtained, and the sharpness and flip-flop property of the formed coating film may be reduced, or metallic There was a tendency for unevenness to occur.

JP 2000-1662 A Japanese Patent Laid-Open No. 9-272796 JP 2002-69430 A

  An object of the present invention is to provide a copolymer having a viscosity characteristic that exhibits high viscosity and has a viscosity characteristic that decreases as the shear rate increases, and in particular, in a water-based paint containing a surfactant, And a copolymer having a viscosity characteristic in which the viscosity decreases as the shear rate increases. Another object of the present invention is to provide a coating material containing the above copolymer and capable of forming a coating film having excellent smoothness and sharpness. Another object of the present invention is to provide a coating material that can form a coating film having excellent glossiness that contains the copolymer and the brightness pigment, has high flip-flop properties, and suppresses metallic unevenness. Moreover, it is providing the coating-film formation method using the said coating material, and the articles | goods with which this coating material was coated.

  As a result of intensive studies to achieve the above object, the present inventors have obtained a polymerizable unsaturated monomer having a graft polymer structure having a main chain and a side chain, and the main chain having a hydrophilic group. It is obtained by polymerizing a monomer component containing, and obtained by polymerizing a monomer component containing a polymerizable unsaturated monomer in which the side chain has a urea bond, a urethane bond, and / or an imide bond. It has been found that a copolymer containing a high molecular weight polymer has a viscosity characteristic that the viscosity is high and the viscosity decreases as the shear rate increases. In particular, the copolymer has a viscosity characteristic that develops a viscosity even in a water-based paint containing a surfactant, and the viscosity decreases as the shear rate increases.

  That is, the present invention includes the following copolymer and a viscosity modifier comprising the copolymer, an aqueous paint containing the copolymer, a method for forming a coating film using the aqueous paint, and the aqueous paint. Articles are provided.

  1. (M-1) (a) From the group consisting of a polymerizable unsaturated monomer (a1) having a urea bond, a polymerizable unsaturated monomer (a2) having a urethane bond, and a polymerizable unsaturated monomer (a3) having an imide bond Polymerize monomer component (I) comprising 5 to 100% by mass of at least one polymerizable unsaturated monomer selected and (b) 0 to 95% by mass of polymerizable unsaturated monomer other than the polymerizable unsaturated monomer (a). A macromonomer having a basic skeleton composed of a polymer having a number average molecular weight within the range of 1,000 to 10,000, and having a polymerizable unsaturated group, and (m-2) a hydrophilic group A copolymer obtained by copolymerizing a monomer component (m) containing a polymerizable unsaturated monomer having

  2. A polymerizable unsaturated monomer having a hydrophilic group (m-2) is N-substituted (meth) acrylamide, a polymerizable unsaturated monomer having a polyoxyalkylene chain, N-vinyl-2-pyrrolidone, 2-hydroxyethyl acrylate, Item 4. The copolymer according to Item 1, which is at least one polymerizable unsaturated monomer selected from the group consisting of acrylic acid and methacrylic acid.

  3. The monomer component (m) is based on the total mass of the monomer component (m), the macromonomer (m-1) 1 to 40% by mass, the polymerizable unsaturated monomer (m-2) 5 to 99 having a hydrophilic group Item 1 or 2 above, comprising from 0 to 94% by mass of the polymerizable unsaturated monomer (m-3) other than the polymerizable unsaturated monomer (m-1) and (m-2). The copolymer described.

  4). Any one of Items 1 to 3, wherein the monomer component (I) contains, as at least a part thereof, 5 to 60% by mass of a hydroxyl group-containing polymerizable unsaturated monomer based on the total mass of the monomer component (I). The copolymer according to item.

  5. 5. An aqueous coating composition containing the copolymer according to any one of items 1 to 4 and a film-forming resin (A).

  6). Item 6. The aqueous coating composition according to Item 5, wherein the film-forming resin (A) is a resin having an ester bond.

  7). Item 7. The aqueous coating composition according to Item 5 or 6, wherein the film-forming resin (A) is a water-dispersible acrylic resin obtained by emulsion polymerization using a surfactant.

  8). 8. An article coated with the aqueous coating composition according to any one of items 5 to 7.

9. (1) A step of applying a water-based coating composition according to any one of the above items 5 to 7 to a substrate to form a base coat film,
(2) a step of applying a clear coat coating composition on the uncured base coat film to form a clear coat film; and (3) the uncured base coat film and the uncured clear coat. A method for forming a multilayer coating film comprising a step of heating a coating film to simultaneously cure both coating films.

10. (1) A step of forming a first colored coating film by applying a first colored coating composition to an object to be coated;
(2) A step of forming the second colored coating film by applying the aqueous coating composition according to any one of Items 5 to 7 on the uncured first colored coating film,
(3) a step of applying a clear coat coating composition on the uncured second colored coating to form a clear coat coating; and (4) the uncured first colored coating, A multilayer coating film forming method comprising a step of simultaneously heating and curing a cured second colored coating film and an uncured clear coat film.

  11. Item having a multilayer coating film formed by the multilayer coating film forming method according to Item 9 or 10.

  12 The viscosity regulator which consists of a copolymer of any one of said claim | item 1-4.

  13. (A) At least one selected from the group consisting of a polymerizable unsaturated monomer (a1) having a urea bond, a polymerizable unsaturated monomer (a2) having a urethane bond, and a polymerizable unsaturated monomer (a3) having an imide bond By polymerizing the monomer component (I) consisting of 5 to 100% by mass of the polymerizable unsaturated monomer and (b) 0 to 95% by mass of the polymerizable unsaturated monomer other than the polymerizable unsaturated monomer (a), 1 And a step of obtaining a macromonomer (m-1) having a basic skeleton composed of a polymer having a number average molecular weight within the range of 10,000 to 10,000 and having a polymerizable unsaturated group, and the obtained macromonomer (M-1) and the process of copolymerizing the monomer component (m) containing the polymerizable unsaturated monomer (m-2) which has a hydrophilic group, The manufacturing method of the copolymer characterized by the above-mentioned .

  The copolymer of the present invention has a viscosity characteristic in which the viscosity is highly expressed and the viscosity decreases as the shear rate increases. In particular, even in a water-based paint containing a surfactant, it has a viscosity characteristic that expresses viscosity and decreases with increasing shear rate. Moreover, according to the aqueous coating material of this invention, the coating film which has the outstanding smoothness and sharpness can be formed. Moreover, according to the water-based paint of the present invention, it is possible to form a coating film having excellent glitter with high flip-flop properties and suppressed metallic unevenness.

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

I. Copolymer of the Present Invention The present invention provides (m-1) (a) a polymerizable unsaturated monomer (a1) having a urea bond, a polymerizable unsaturated monomer (a2) having a urethane bond, and a polymerizable having an imide bond. 5 to 100% by mass of at least one polymerizable unsaturated monomer selected from the group consisting of the unsaturated monomer (a3) and (b) 0 to 95% of a polymerizable unsaturated monomer other than the polymerizable unsaturated monomer (a). % Having a basic skeleton made of a polymer having a number average molecular weight in the range of 1,000 to 10,000 obtained by polymerizing the monomer component (I) comprising 1%, and having a polymerizable unsaturated group A copolymer obtained by copolymerizing a monomer component (m) containing a monomer and (m-2) a polymerizable unsaturated monomer having a hydrophilic group is provided.

  The copolymer of the present invention has a viscosity characteristic in which the viscosity is highly expressed and the viscosity decreases as the shear rate increases. In particular, even in a water-based paint containing a surfactant, it has a viscosity characteristic that expresses viscosity and decreases with increasing shear rate. Because of having such excellent viscosity characteristics, the copolymer of the present invention is preferably used as a viscosity modifier. Especially, since it can form the coating film which has the outstanding smoothness, sharpness, and glitter, it can be used suitably as a viscosity regulator for coating materials.

  In the present invention, the polymerizable unsaturated monomer refers to a monomer having one or more (for example, 1 to 4) polymerizable unsaturated groups. The polymerizable unsaturated group means an unsaturated group capable of radical polymerization. Examples of the polymerizable unsaturated group include a vinyl group, a (meth) acryloyl group, a (meth) acrylamide group, a vinyl ether group, and an allyl group.

Polymerizable unsaturated monomer having a urea bond (a1)
The polymerizable unsaturated monomer (a1) having a urea bond is a polymerizable unsaturated monomer having a urea bond (also referred to as a urea bond) represented by -NH-CO-NH-.

  The polymerizable unsaturated monomer (a1) having a urea bond can be obtained, for example, by reacting the following isocyanate unsaturated group-containing polymerizable unsaturated monomer with an amine compound.

Isocyanato group-containing polymerizable unsaturated monomer Examples of the isocyanato group-containing polymerizable unsaturated monomer include 2- (meth) acryloyloxyethyl isocyanate; m-isopropenyl-α, α-dimethylbenzyl isocyanate; hydroxyl group-containing polymerizable unsaturated monomer. Reaction products of monomers and diisocyanate compounds; hydroxyl group-containing polymerizable unsaturated monomers, reaction products of diol compounds and diisocyanate compounds, and the like, which can be used alone or in combination of two or more. Especially, it is preferable that isocyanato group containing polymerizable unsaturated monomer is 2-acryloyloxyethyl isocyanate and / or 2-methacryloyloxyethyl isocyanate, and it is more preferable that it is 2-methacryloyloxyethyl isocyanate.

  Examples of the hydroxyl group-containing polymerizable unsaturated monomer used in the reaction product of the hydroxyl group-containing polymerizable unsaturated monomer and diisocyanate compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3 -Monoesterified product of (meth) acrylic acid such as hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate and a dihydric alcohol having 2 to 8 carbon atoms; the (meth) acrylic acid and 2 to 2 carbon atoms Ε-caprolactone modified product of monoesterified product with dihydric alcohol of 8; N-hydroxymethyl (meth) acrylamide; allyl alcohol; (meth) acrylate having a polyoxyethylene chain whose molecular terminal is a hydroxyl group, etc. These can be used alone or in combination of two or more. It can be.

  In the present specification, “(meth) acrylate” means acrylate or methacrylate, and “(meth) acrylic acid” means acrylic acid or methacrylic acid. In addition, “(meth) acryloyl” means acryloyl or methacryloyl, and “(meth) acrylamide” means “acrylamide or methacrylamide”.

  Examples of the diisocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,2-butylene diisocyanate, 2,3-butylene diisocyanate, 1,3. -Aliphatic diisocyanate compounds such as butylene diisocyanate, 2,4,4- or 2,2,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, methyl 2,6-diisocyanatohexanoate (common name: lysine diisocyanate); 1,3-cyclopentene diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-cyclohexane diisocyanate, 3-isocyanatomethyl-3, , 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 fats such as 1,4-bis (isocyanatomethyl) cyclohexane (common name: hydrogenated xylylene diisocyanate) or a mixture thereof, methylene bis (4,1-cyclohexanediyl) diisocyanate (common name: hydrogenated MDI), norbornane diisocyanate, etc. Cyclic diisocyanate compound; methylene bis (4,1-phenylene) diisocyanate (common name: MDI), 1,3- or 1,4-xylylene diisocyanate or a mixture thereof, ω, ω′-diisocyanato-1,4-diethylben Araliphatic diisocyanate compounds such as zen, 1,3- or 1,4-bis (1-isocyanato-1-methylethyl) benzene (common name: tetramethylxylylene diisocyanate) or mixtures thereof; m-phenylene diisocyanate, p -Phenylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 2,4-tolylene diisocyanate (common name: 2,4-TDI) or 2,6-tolylene diisocyanate (common name: 2, 6-TDI) or a mixture thereof, an aromatic diisocyanate compound such as 4,4′-toluidine diisocyanate, 4,4′-diphenyl ether diisocyanate; a compound obtained by reacting the above diisocyanate compound with a diol compound under an excess of isocyanato groups Etc., and these may be used alone or in combination.

  Moreover, reaction of the said hydroxyl-containing polymerizable unsaturated monomer and the said diisocyanate compound can be performed by a known method.

  Examples of the diol compound used in the reaction product of the hydroxyl group-containing polymerizable unsaturated monomer, diol compound, and diisocyanate compound include alkyl diol, polyether diol, polyester diol, polycarbonate diol, and the like. It can be used alone or in combination of two or more.

  For example, the reaction product may react these components at a blending ratio in which the amount of the isocyanate group derived from the diisocyanate compound is larger than the total amount of the hydroxyl group derived from the hydroxyl group-containing polymerizable unsaturated monomer and the diol compound. Can be obtained. The reaction product is usually a compound having two or more urethane bonds and isocyanato groups in one molecule.

  Moreover, as a commercial item of the said isocyanate group containing polymerizable unsaturated monomer, "Karenz MOI", "Karenz AOI", "Karenz MOI-EG" (above, Showa Denko Co., Ltd. product) etc. are mentioned, for example.

Amine compound The amine compound is preferably a primary amine compound or a secondary amine compound, and more preferably a primary amine compound. The amine compound may have a hydroxyl group.

  Examples of the primary amine compound include ethylamine, propylamine (n-propylamine, isopropylamine), butylamine (n-butylamine, sec-butylamine, tert-butylamine), n-pentylamine, 1-methylbutylamine, 1 -Ethylpropylamine, 2-ethylbutylamine, hexylamine, n-octylamine, 2-ethylhexylamine, decylamine, stearylamine, cyclohexylamine, ethanolamine, 6-aminohexanol, p-methoxybenzylamine, methoxypropylamine, 3 , 4-dimethoxyphenylethylamine, 2,5-dimethoxyaniline, furfurylamine, tetrahydrofurfurylamine, benzylamine, aniline, hexamethylenediamine, etc. Is, it may be used alone or in combination. Of these, ethylamine, propylamine, butylamine and 2-ethylhexylamine are preferred, and butylamine is more preferred from the viewpoint of improving the smoothness and sharpness of the coating film formed from the coating material containing the copolymer of the present invention.

Examples of the secondary amine compound include diethylamine, dipropylamine, dibutylamine (di-n-butylamine, di-sec-butylamine, di-tert-butylamine), diisopropylamine, diisobutylamine, dipentylamine, and dioctyl. Amine (di-n-octylamine, di-2-ethylhexylamine), didecylamine, distearylamine, N-ethyl-1,2-dimethylpropylamine, N-methylbutylamine, N-butylethylamine, diethanolamine, diisopropanolamine , 2- (methylamino) ethanol, 2- (isopropylamino) ethanol, 2- (ethylamino) ethanol, piperidine, hexamethyleneimine, morpholine, and the like. In combination can be used.

  The reaction between the isocyanato group-containing polymerizable unsaturated monomer and the amine compound is carried out by the equivalent ratio of the isocyanato group present in the isocyanato group-containing polymerizable unsaturated monomer and the active hydrogen present in the amine compound (active hydrogen / Isocyanato group) is reacted at a ratio such that 0.5 / 1 to 2/1, preferably 0.7 / 1 to 1.5 / 1, more preferably 0.8 / 1 to 1.2 / 1. And can be carried out by a known method.

  The reaction of the above-mentioned isocyanato group-containing polymerizable unsaturated monomer and the amine compound can be carried out by a known method by mixing the both and raising the temperature as desired. This reaction is desirably performed at a temperature of 5 to 70 ° C, preferably 20 to 50 ° C. The above reaction components can be mixed by a known method, for example, by adding an amine compound to an isocyanate group-containing polymerizable unsaturated monomer. Moreover, the addition of the above reaction components can be carried out in several stages as desired. The above reaction can be performed in the presence of an organic solvent such as acetone, methyl isobutyl ketone, benzene, toluene, xylene, tetrahydrofuran, an aliphatic hydrocarbon solvent (petroleum ether, etc.) and the like.

  Specific examples of the polymerizable unsaturated monomer (a1) having a urea bond include, for example, 2- (3-ethylureido) ethyl methacrylate obtained by reacting 2-methacryloyloxyethyl isocyanate and ethylamine; 2-methacryloyloxy 2- (3-isopropylureido) ethyl methacrylate obtained by reacting ethyl isocyanate and isopropylamine; 2- (3-butylureido) ethyl methacrylate obtained by reacting 2-methacryloyloxyethyl isocyanate and butylamine; 2-methacryloyl 2- [3- (2-ethylhexyl) ureido] ethyl methacrylate obtained by reacting oxyethyl isocyanate and 2-ethylhexylamine; 2-methacryloyloxyethyl isocyanate 2- (3,3-diethylureido) ethyl methacrylate obtained by reacting a salt with diethylamine; 2-{[5- (3-butylureido] obtained by reacting 2-hydroxyethyl methacrylate, isophorone diisocyanate and butylamine ) -1,3,3-trimethylcyclohexyl] methylcarbamoyloxy} ethyl methacrylate and 2- {3-[(3-butylureido) methyl] -3,5,5-trimethylcyclohexylmethylcarbamoyloxy} ethyl methacrylate Etc. Of these, 2- (3-butylureido) ethyl methacrylate obtained by reacting 2-methacryloyloxyethyl isocyanate and butylamine is preferable.

Polymerizable unsaturated monomer having urethane bond (a2)
The polymerizable unsaturated monomer (a2) having a urethane bond is a polymerizable unsaturated monomer having a urethane bond represented by -NH-CO-O-.

  The polymerizable unsaturated monomer (a2) having a urethane bond is, for example, a method of reacting an isocyanate group-containing polymerizable unsaturated monomer and a hydroxyl group-containing compound; reacting a hydroxyl group-containing polymerizable unsaturated monomer and an isocyanate group-containing compound. It can obtain by the method of making it.

  The isocyanate unsaturated group-containing polymerizable unsaturated monomer that can be used in the method of reacting the isocyanate unsaturated group-containing polymerizable unsaturated monomer with the hydroxyl group-containing compound is described in the explanation column of the polymerizable unsaturated monomer having a urea bond (a1). Examples include the isocyanate group-containing polymerizable unsaturated monomers described. Especially, it is preferable that this isocyanato group containing polymerizable unsaturated monomer is 2-methacryloyloxyethyl isocyanate from a stability viewpoint at the time of reaction.

  Examples of the hydroxyl group-containing compound include methanol, ethanol, propanol, butanol, pentanol, hexanol, cyclohexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecanol, hexadecanol, Alkanols such as decanol, heptadecanol, octadecanol; propylene glycol monomethyl ether, propylene glycol monopropyl ether, ethylene glycol monobutyl ether, polyethylene glycol monomethyl ether, polyethylene glycol monoethyl ether, polypropylene glycol monomethyl ether, polyoxyethylene Ether groups such as polyoxypropylene monomethyl ether Monools: ethylene glycol, propylene glycol, polyethylene glycol, polypropylene glycol, butanediol, polytetramethylene glycol, methylpropanediol, pentanediol, methylpentanediol, hexanediol, neopentylglycol, 2-butyl-2-ethyl -1,3-propanediol, 2,2′-diethyl-1,3-propanediol, 1,4-cyclohexanedimethanol, tricyclodecane dimethanol, 2-ethyl-1,3-hexanediol, 2,2 Diols such as 1,4-trimethyl-1,3-pentanediol, hydroxypivalic acid-neopentylglycol ester, dimethylolpropanoic acid, dimethylolbutanoic acid; trimethylolethane, trimethylo Polyols such as propane, trimethylolbutane, trimethyloloctane, glycerin, pentaerythritol; ring-opening adducts of the above-mentioned compounds having a hydroxyl group with ethylene oxide, propylene oxide, tetrahydrofuran, lactone and / or cyclocarbonate; having an amino group Ring-opening adduct of a compound and ethylene oxide, propylene oxide, tetrahydrofuran, lactone and / or cyclocarbonate; reaction product of a compound having both amino group and hydroxyl group in one molecule and an epoxy group-containing compound; Reaction product of compound having both amino group and hydroxyl group and polyisocyanate; hydroxyl group-containing polyester resin, hydroxyl group-containing polyurethane resin, hydroxyl group-containing polycarbonate resin, hydroxyl group-containing vinyl polymer, epoxy Well-known polyols, such as resin, etc. are mentioned, These can be used individually or in combination of 2 or more types.

  Especially, it is preferable that the said hydroxyl-containing compound is a C2-C8 alkanol from a stability viewpoint at the time of reaction. Examples of the alkanol having 2 to 8 carbon atoms include ethanol, propanol, butanol, pentanol, hexanol, cyclohexanol, heptanol, n-octanol, 2-ethyl-1-hexanol, and the like. -Ethyl-1-hexanol is preferred.

  Examples of the hydroxyl group-containing polymerizable unsaturated monomer used in the method of reacting the hydroxyl group-containing polymerizable unsaturated monomer with the isocyanato group-containing compound include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl ( Monoesterified products of (meth) acrylic acid such as (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. and a dihydric alcohol having 2 to 8 carbon atoms; the (meth) acrylic acid Ε-caprolactone modified product of monoesterified product of dihydric alcohol having 2 to 8 carbon atoms; N-hydroxymethyl (meth) acrylamide; allyl alcohol; (meth) acrylate having polyoxyethylene chain whose molecular terminal is a hydroxyl group These may be used alone or in combination of two or more. Together it can be used. Among these, from the viewpoint of stability during the reaction, the hydroxyl group-containing polymerizable unsaturated monomer is preferably 2-hydroxyethyl methacrylate.

  The isocyanate group-containing compound includes, for example, the diisocyanate compound described in the description of the polymerizable unsaturated monomer (a1) having a urea bond; the diisocyanate compound, and an active hydrogen-containing compound such as a monoalcohol or an amine. The monoisocyanate compound etc. which are obtained by making these react are mentioned, These can be used individually or in combination of 2 or more types.

Polymerizable unsaturated monomer having an imide bond (a3)
Examples of the polymerizable unsaturated monomer having an imide bond include hexahydrophthalimide ethyl acrylate (Aronix M-140: product of Toa Gosei Co., Ltd.), hexahydrophthalimide propylene acrylate, phthalimide ethyl methacrylate, and the like. Or it can use in combination of 2 or more types. Moreover, this monomer can also be synthesize | combined and the synthesis method is clarified by the following well-known literature, for example.
(1) Kiyoshi Kato et al., Journal of Synthetic Organic Chemistry 30 (10), 897, (1972),
(2) Javier de Abajo et al., Polymer, vol 33 (5), (1992),
(3) JP-A-56-53119,
(4) Japanese Laid-Open Patent Publication No. 1-242569,
(5) JP 2001-172336 A.

Polymerizable unsaturated monomer (b) other than polymerizable unsaturated monomer (a)
The polymerizable unsaturated monomer (b) is other than the polymerizable unsaturated monomer (a1) having a urea bond, the polymerizable unsaturated monomer (a2) having a urethane bond, and the polymerizable unsaturated monomer (a3) having an imide bond. The polymerizable unsaturated monomer.

  Examples of the polymerizable unsaturated monomer (b) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, iso-propyl (meth) acrylate, n-butyl (meth) acrylate, Isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, dodecyl (meth) Acrylate (lauryl (meth) acrylate), tridecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate Rate, alkyl such as t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate, tricyclodecanyl (meth) acrylate, or cycloalkyl (meth) acrylate, etc. Alkyl (meth) acrylate having an alkyl group having 1 to 24 carbon atoms; aromatic ring-containing polymerizable unsaturated monomer such as benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene; vinyltrimethoxysilane, vinyltriethoxy Heavy compounds having alkoxysilyl groups such as silane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane Unsaturated monomers; perfluoroalkyl (meth) acrylates such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate; polymerizable unsaturated monomers having a fluorinated alkyl group such as fluoroolefin; N- Vinyl compounds such as vinyl pyrrolidone, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxy Monoesterified product of (meth) acrylic acid such as butyl (meth) acrylate and a dihydric alcohol having 2 to 8 carbon atoms, monoesterified product of the (meth) acrylic acid and a dihydric alcohol having 2 to 8 carbon atoms ε-caprolactone Hydroxyl-containing polymerizable unsaturated monomers such as N-hydroxymethyl (meth) acrylamide, allyl alcohol, (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end; (meth) acrylic acid, maleic acid Carboxyl group-containing polymerizable unsaturated monomers such as crotonic acid and β-carboxyethyl acrylate; allyl (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) Acrylate, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanedi All di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethanedi (meth) acrylate, 1,1,1 -At least a polymerizable unsaturated group such as trishydroxymethylethane tri (meth) acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, triallyl isocyanurate, diallyl terephthalate, divinylbenzene in one molecule. Two polymerizable unsaturated monomers: (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylamino Nitrogen-containing polymerizable unsaturated monomers such as propyl (meth) acrylamide, adducts of glycidyl (meth) acrylate and amines; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl Epoxy group-containing polymerizable unsaturated monomers such as (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and allyl glycidyl ether; molecular terminals are alkoxy groups (Meth) acrylates having polyoxyethylene chains; acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formylstyrol, 4-7 carbon atoms Examples thereof include carbonyl group-containing polymerizable unsaturated monomers such as dialkyl ketones (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone). These polymerizable unsaturated monomers can be used alone or in combination of two or more.

Monomer component (I)
The monomer component (I) is composed of the polymerizable unsaturated monomer (a1) having a urea bond, the polymerizable unsaturated monomer (a2) having a urethane bond, and the polymerizable unsaturated monomer (a3) having an imide bond. It consists of 5 to 100% by mass of at least one polymerizable unsaturated monomer (a) selected and 0 to 95% by mass of polymerizable unsaturated monomer (b) other than the polymerizable unsaturated monomer (a).

In the monomer component (I), the blending ratio of the polymerizable unsaturated monomers (a) and (b) is such that the viscosity of the obtained copolymer and the coating film formed by the paint containing the copolymer are as follows. From the viewpoint of improvement in smoothness, sharpness, flip-flop properties and water resistance, and suppression of metallic unevenness, the following ranges are preferable based on the total mass of the monomer component (I).
At least one polymerizability selected from the group consisting of a polymerizable unsaturated monomer (a1) having a urea bond, a polymerizable unsaturated monomer (a2) having a urethane bond, and a polymerizable unsaturated monomer (a3) having an imide bond Total amount of unsaturated monomer (a): 5 to 100% by mass, preferably 30 to 95% by mass, more preferably 45 to 90% by mass,
Polymerizable unsaturated monomer (b) other than polymerizable unsaturated monomer (a): 0 to 95% by mass, preferably 5 to 70% by mass, and more preferably 10 to 55% by mass.

  Moreover, it is preferable that the said monomer component (I) contains a hydroxyl-containing polymerizable unsaturated monomer as at least one part from the viewpoint of the clarity of the coating film formed, and water resistance. Specifically, it is preferable that the polymerizable unsaturated monomer (b) contains a hydroxyl group-containing polymerizable unsaturated monomer as at least a part thereof.

  As the hydroxyl group-containing polymerizable unsaturated monomer, the hydroxyl group-containing polymerizable unsaturated monomer exemplified in the explanation of the polymerizable unsaturated monomer (b) can be used, and among them, 2-hydroxyethyl (meta ) Acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferred, and 2-hydroxyethyl methacrylate is more preferred.

  When the monomer component (I) contains a hydroxyl group-containing polymerizable unsaturated monomer, the use ratio of the hydroxyl group-containing polymerizable unsaturated monomer is determined from the monomer component ( It is suitable that it is in the range of 5 to 60% by mass, preferably 10 to 45% by mass, more preferably 15 to 30% by mass, based on the total mass of I).

  Further, when the monomer component (I) contains a hydroxyl group-containing polymerizable unsaturated monomer, the hydroxyl value of the polymer obtained by polymerizing the monomer component (I) depends on the sharpness and water resistance of the coating film to be formed. From the viewpoint of properties, it is preferable to be within the range of 20 to 260 mgKOH / g, preferably 40 to 200 mgKOH / g, more preferably 60 to 130 mgKOH / g.

  Moreover, the monomer component (I) contains a polymerizable unsaturated monomer having an alkyl group having 4 to 24 carbon atoms as at least a part thereof from the viewpoint of the sharpness and water resistance of the coating film to be formed. It is preferable. Specifically, it is preferable that the polymerizable unsaturated monomer (b) contains a polymerizable unsaturated monomer having an alkyl group having 4 to 24 carbon atoms as at least a part thereof.

  As the polymerizable unsaturated monomer having an alkyl group having 4 to 24 carbon atoms, for example, a monoesterified product of (meth) acrylic acid and a monohydric alcohol having an alkyl group having 4 to 24 carbon atoms can be used. Specifically, for example, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (Meth) acrylate, nonyl (meth) acrylate, dodecyl (meth) acrylate (lauryl (meth) acrylate), tridecyl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methyl Cyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, isobornyl (meth) acrylate, adamantyl (meth) acrylate , Include alkyl or cycloalkyl (meth) acrylates such as tricyclodecanyl (meth) acrylate, and these can be used either alone or in combination of two or more.

  Examples of the polymerizable unsaturated monomer having an alkyl group having 4 to 24 carbon atoms include n-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, and tridecyl methacrylate from the viewpoint of smoothness and sharpness of the resulting coating film. Is preferred.

  When the monomer component (I) contains a polymerizable unsaturated monomer having an alkyl group having 4 to 24 carbon atoms, the use ratio of the polymerizable unsaturated monomer having an alkyl group having 4 to 24 carbon atoms is formed. From the viewpoint of smoothness and sharpness of the coating film, in the range of 1 to 95% by mass, preferably 10 to 90% by mass, more preferably 20 to 80% by mass, based on the total mass of the monomer component (I). It is preferable that

Macromonomer (m-1)
The macromonomer (m-1) is a macromonomer having a polymer and a polymerizable unsaturated group, and is obtained by polymerizing the monomer component (I) to 1,000 to 10,000. It is a macromonomer that is a polymer having a number average molecular weight in the range of 000. In the present invention, the macromonomer is a high molecular weight monomer having a polymerizable unsaturated group, and preferably a high molecular weight monomer having a polymerizable unsaturated group at the end of the polymer. Therefore, the macromonomer (m-1) has a basic skeleton composed of the above polymer and has a structure having at least one, preferably one polymerizable unsaturated group, preferably at the terminal of the polymer. Have

  In this specification, the polymerizable unsaturated group contained in the macromonomer (m-1) means an unsaturated group capable of radical polymerization. Examples of the polymerizable unsaturated group include a vinyl group, a vinylidene group, an acryloyl group, and a methacryloyl group.

  The macromonomer (m-1) preferably has a number average molecular weight in the range of 1,000 to 10,100. Especially, it is suitable that a number average molecular weight exists in the range of 1,000-5,000, preferably 1,000-3,000 from a viewpoint of the smoothness of a coating film obtained, and a sharpness. The number average molecular weight of the macromonomer (m-1) is adjusted by, for example, the amount of chain transfer agent used, the amount of polymerization initiator used, the reaction temperature, the reaction time, etc., when polymerizing the monomer component (I). be able to.

  The macromonomer (m-1) can be obtained by a method known per se. Specifically, for example, it can be obtained by the following method (1), method (2), method (3) and the like.

  Method (1): When polymerizing the monomer component (I), a polymer is obtained by performing polymerization in the presence of a chain transfer agent containing a first chemically reactive group such as a carboxyl group, a hydroxyl group, and an amino group. A first chemically reactive group is introduced at the end of the. Next, by reacting the obtained polymer with a polymerizable unsaturated monomer having a second chemically reactive group capable of reacting with the first chemically reactive group in the polymer, a macromonomer (m -1) can be obtained.

  Examples of the chain transfer agent containing the first chemically reactive group such as a carboxyl group, a hydroxyl group, and an amino group include mercaptoacetic acid, 2-mercaptopropionic acid, 3-mercaptopropionic acid, 2-mercaptoethanol, 2-aminoethane. Thiols and the like can be suitably used.

  Examples of the polymerizable unsaturated monomer having a second chemically reactive group for reacting with the first chemically reactive group in the copolymer to introduce a polymerizable unsaturated group include the first chemical When the reactive group is a carboxy group, an epoxy group-containing polymerizable unsaturated monomer; when the first chemically reactive group is a hydroxyl group; an isocyanato group-containing polymerizable unsaturated monomer; When the functional group is an amino group, an epoxy group-containing polymerizable unsaturated monomer can be preferably used.

  As said epoxy-group-containing polymerizable unsaturated monomer, glycidyl acrylate, glycidyl methacrylate, etc. can be used conveniently, for example. Moreover, as said isocyanato group containing polymerizable unsaturated monomer, 2- (meth) acryloyloxyethyl isocyanate, m-isopropenyl- (alpha), (alpha)-dimethylbenzyl isocyanate, etc. can be used conveniently, for example.

  Method (2): The macromonomer (m-1) can be obtained by catalytic chain transfer polymerization (CCTP method) using a metal complex. The CCTP method is described, for example, in JP-B-6-23209, JP-B-7-35411, JP-B-9-501457, JP-A-9-176256, Macromolecules 1996, 29, 8083-8089, and the like. ing. Specifically, the macromonomer (m-1) can be produced by subjecting the monomer component (I) to catalytic chain transfer polymerization in the presence of a metal complex. The catalytic chain transfer polymerization can be performed by, for example, a solution polymerization method in an organic solvent, an emulsion polymerization method in water, or the like. Moreover, in the case of superposition | polymerization, you may use a radical polymerization initiator as needed in addition to the said metal complex.

Examples of the metal complex include a cobalt complex, an iron complex, a nickel complex, a ruthenium complex, a rhodium complex, a palladium complex, a rhenium complex, and an iridium complex. Of these, the cobalt complex is efficiently used as a catalytic chain transfer agent. Works. The amount of the metal complex to be used is not particularly limited, but is usually 1 × 10 ⁻⁶ to 1 part by mass, preferably 1 × 10 ^{−4 based on} 100 parts by mass of the total mass of the monomer component (I). It is suitable to be in the range of ~ 0.5 parts by mass.

  Examples of the radical polymerization initiator include benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert-butyl peroxide, di-tert-amyl peroxide, and tert-butyl peroxide. Organic peroxides such as oxy-2-ethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, diisopropylbenzene hydroperoxide; azobisisobutyronitrile Azobis (2,4-dimethylvaleronitrile), azobis (2-methylpropiononitrile), azobis (2-methylbutyronitrile), 4,4′-azobis (4-si Anobutanoic acid), dimethylazobis (2-methylpropionate), azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], azobis {2-methyl-N- [2- (1-hydroxy Butyl)]-propionamide}; persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate, and the like. These polymerization initiators can be used alone or in combination of two or more. The blending amount of the radical polymerization initiator is not particularly limited, but is usually 0.1 to 10 parts by weight, preferably 0.1 to 0.1 parts by weight based on 100 parts by weight of the total weight of the monomer component (I). It is suitable that it is in the range of 8 parts by mass, more preferably 0.1 to 6 parts by mass.

  Method (3): The macromonomer (m-1) can be obtained by an addition cleavage type chain transfer polymerization method using an addition cleavage type chain transfer agent. The addition-cleavage type chain transfer polymerization method is described in, for example, JP-A-7-2954. Specifically, the macromonomer (m-1) can be produced by subjecting the monomer component (I) to addition-cleavage chain transfer polymerization in the presence of the addition-cleavage chain transfer agent. The addition-cleavage chain transfer polymerization can be performed by, for example, a solution polymerization method in an organic solvent, an emulsion polymerization method in water, or the like. Moreover, in the case of superposition | polymerization, in addition to this addition cleavage type | mold chain transfer agent, a radical polymerization initiator can be used together as needed.

  For example, 2,4-diphenyl-4-methyl-1-pentene (sometimes abbreviated as “α-methylstyrene dimer” or “MSD”) is preferably used as the addition-cleavage chain transfer agent. be able to. The compounding amount of the addition-cleavage type chain transfer agent is not particularly limited, but is usually 1 to 20 parts by mass, preferably 2 to 15 parts by mass, based on 100 parts by mass of the total mass of the monomer component (I). Parts, more preferably in the range of 3 to 10 parts by weight.

  As the radical polymerization initiator, for example, the radical polymerization initiator described in the description of the method (2) can be used. These polymerization initiators can be used alone or in combination of two or more. The blending amount of the radical polymerization initiator is not particularly limited, but is usually 1 to 20 parts by mass, preferably 2 to 15 parts by mass based on 100 parts by mass of the total mass of the monomer component (I). More preferably, it is in the range of 3 to 10 parts by mass.

  In the above methods (1) to (3), the polymerization temperature varies depending on the kind of the radical polymerization initiator, but is in the range of 60 to 200 ° C, preferably 80 to 180 ° C, more preferably 90 to 170 ° C. Is preferred. The temperature may be different between the first half and the second half of the polymerization, and the polymerization may be performed while gradually changing the temperature.

  Among the methods (1) to (3), the method (1) is a step of polymerizing the monomer component (I) to obtain a polymer, and reacting the obtained polymer with a polymerizable unsaturated monomer. Two reaction steps including a step of introducing a polymerizable unsaturated group into the polymer are necessary. In addition, since the method (2) uses a metal complex, catalytic chain transfer polymerization may occur during the production of a copolymer (graft polymer) described later, and the resulting copolymer may be colored. is there.

  For this reason, the macromonomer (m-1) is an addition-cleavage-type chain using the addition-cleavage-type chain transfer agent of the method (3) from the viewpoints of reducing the number of reaction steps and suppressing the coloring in the resulting copolymer. It is preferable to obtain by a transfer polymerization method.

  Moreover, the said macromonomer (m-1) can be used individually or in combination of 2 or more types.

Polymerizable unsaturated monomer having a hydrophilic group (m-2)
In the present invention, examples of the polymerizable unsaturated monomer (m-2) having a hydrophilic group include N-substituted (meth) acrylamide, a polymerizable unsaturated monomer having a polyoxyalkylene chain, and N-vinyl-2-pyrrolidone. , 2-hydroxyethyl acrylate, carboxyl group-containing polymerizable unsaturated monomer, polymerizable unsaturated monomer having a sulfonic acid group, phosphoric acid group-containing polymerizable unsaturated monomer, and the like. Can be used in combination.

  Among these, as the polymerizable unsaturated monomer (m-2) having a hydrophilic group, N-substituted (meth) acrylamide, polymerizable unsaturated monomer having a polyoxyalkylene chain, N-vinyl-2-pyrrolidone, 2- At least one polymerizable unsaturated monomer selected from the group consisting of hydroxyethyl acrylate, acrylic acid and methacrylic acid can be suitably used. These can be used alone or in combination of two or more.

In the monomer component (m), the content ratio of the macromonomer (m-1) and the polymerizable unsaturated monomer (m-2) having a hydrophilic group is determined according to the smoothness, sharpness, and brightness of the coating film to be formed. From the viewpoint of water resistance and water resistance, it is preferably within the following range based on the total mass of the monomer component (m):
Macromonomer (m-1): 1 to 40% by mass, preferably 3 to 29% by mass, more preferably 5 to 15% by mass,
Polymerizable unsaturated monomer (m-2) having a hydrophilic group: 5 to 99% by mass, preferably 10 to 97% by mass, and more preferably 20 to 95% by mass.

  Examples of the N-substituted (meth) acrylamide include N-methyl acrylamide, N-methyl methacrylamide, N-methylol acrylamide butyl ether, N-methylol methacrylamide butyl ether, N-ethyl acrylamide, N-ethyl methacrylamide, N- n-propylacrylamide, Nn-propylmethacrylamide, N-isopropylacrylamide, N-isopropylmethacrylamide, N-cyclopropylacrylamide, N-cyclopropylmethacrylamide, diacetoneacrylamide, diacetonemethacrylamide, N-hydroxymethyl Acrylamide, N-hydroxymethyl methacrylamide, N-hydroxyethyl acrylamide, N-hydroxyethyl methacrylamide, N, N- Methyl acrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide, N-methyl, N-ethylacrylamide, N-methyl, N-ethylmethacrylamide, N, N-dimethyl Aminopropyl acrylamide, N, N-dimethylaminopropyl methacrylamide, N-methylol acrylamide methyl ether, N-methylol methacrylamide methyl ether, N-methylol acrylamide ethyl ether, N-methylol methacrylamide ethyl ether, N-methylol acrylamide propyl ether , N-methylol methacrylamide propyl ether, acryloyl morpholine, methacryloyl morpholine and the like. It can be used in combination on.

  Among these, Nn-propyl acrylamide, Nn-propyl methacrylamide, N-isopropyl acrylamide, N-isopropyl methacrylamide, N-hydroxyethyl acrylamide from the viewpoint of smoothness and sharpness of the formed coating film , N-hydroxyethylmethacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N, N-diethylmethacrylamide are preferred, N, N-dimethylacrylamide, N, N -More preferred is dimethylmethacrylamide.

  The polymerizable unsaturated monomer having a polyoxyalkylene chain is a monomer containing a polyoxyalkylene chain and a polymerizable unsaturated group in one molecule.

  Examples of the polyoxyalkylene chain include a polyoxyethylene chain, a polyoxypropylene chain, a chain composed of a polyoxyethylene block and a polyoxypropylene block, and a chain formed by randomly bonding polyoxyethylene and polyoxypropylene. These polyoxyalkylene chains generally have a molecular weight in the range of about 100 to 5,000, preferably about 200 to 4,000, more preferably about 300 to 3,000. It is.

  Representative examples of the polymerizable unsaturated monomer having a polyoxyalkylene chain include, for example, the following general formula (1)

[Wherein, R ¹ represents a hydrogen atom or a methyl group, R ² represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, preferably a hydrogen atom, a methyl group or an ethyl group, more preferably a hydrogen atom or a methyl group. R ³ represents an alkylene group having 2 to 4 carbon atoms, preferably 2 or 3 carbon atoms, more preferably 2 carbon atoms, and m is 3 to 150, preferably 5 to 80, more preferably 8 to 50. Represents an integer, and the m oxyalkylene units (O—R ³ ) may be the same as or different from each other]
The polymerizable unsaturated monomer shown by these can be mentioned.

  Specific examples of the polymerizable unsaturated monomer represented by the general formula (1) include, for example, tetraethylene glycol (meth) acrylate, methoxytetraethylene glycol (meth) acrylate, ethoxytetraethylene glycol (meth) acrylate, n- Butoxytriethylene glycol (meth) acrylate, n-butoxytetraethylene glycol (meth) acrylate, tetrapropylene glycol (meth) acrylate, methoxytetrapyroprene glycol (meth) acrylate, ethoxytetrapropylene glycol (meth) acrylate, n-butoxy Tetrapropylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene (polypropylene glycol) Pyrene) glycol (meth) acrylate, methoxy polyethylene glycol (meth) acrylate, ethoxy polyethylene glycol (meth) acrylate, methoxy polypropylene glycol (meth) acrylate, ethoxy polypropylene glycol (meth) acrylate, methoxy polyethylene (propylene) glycol (meth) acrylate And ethoxypolyethylene (propylene) glycol (meth) acrylate and the like, and these can be used alone or in combination of two or more. In the present specification, “polyethylene (propylene) glycol” means a copolymer of ethylene glycol and propylene glycol, and includes both a block copolymer and a random copolymer.

  Among these, polyethylene glycol (meth) acrylate, polyethylene (propylene) glycol (meth) acrylate, methoxypolyethylene glycol (meth) acrylate, methoxypolyethylene (propylene) glycol from the viewpoint of smoothness and sharpness of the formed coating film (Meth) acrylate is preferable, and polyethylene glycol (meth) acrylate and methoxypolyethylene glycol (meth) acrylate are more preferable.

  The polymerizable unsaturated monomer having a polyoxyalkylene chain generally has a molecular weight in the range of about 300 to 6,000, preferably about 400 to 5,000, more preferably about 450 to 3,500. Is preferred.

  Examples of the carboxyl group-containing polymerizable unsaturated monomer include (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and the like, and these are used alone or in combination of two or more. be able to.

  Examples of the polymerizable unsaturated monomer having a sulfonic acid group include 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, allylsulfonic acid, 4-styrenesulfonic acid, and the like; A sodium salt, an ammonium salt, etc. are mentioned, These can be used individually or in combination of 2 types or more, respectively.

  Examples of the phosphoric acid group-containing polymerizable unsaturated monomer include 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, 2-methacryloyloxypropyl acid phosphate, and the like. These can be used alone or in combination of two or more.

Other polymerizable unsaturated monomers (m-3)
The other polymerizable unsaturated monomer (m-3) is a polymerizable unsaturated monomer other than the macromonomer (m-1) and the polymerizable unsaturated monomer (m-2) having a hydrophilic group. The other polymerizable unsaturated monomer (m-3) can be appropriately selected and used as necessary according to the properties desired for the copolymer.

Specific examples of the other polymerizable unsaturated monomer (m-3) 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, tridecyl (meth) Acrylate, lauryl (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, ethylene, butadiene, chloroprene, vinyl propionate, vinyl acetate and the like.
(X) Hydroxyl-containing polymerizable unsaturated monomer: (Meth) such as 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, etc. Monoesterified product of acrylic acid and divalent alcohol having 2 to 8 carbon atoms; ε-caprolactone modified product of monoesterified product of (meth) acrylic acid and divalent alcohol having 2 to 8 carbon atoms; allyl alcohol and the like.
(Xi) Nitrogen-containing polymerizable unsaturated monomer: For example, (meth) acrylonitrile, (meth) acrylamide, methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, 2- (methacryloyloxy) ethyltrimethylammonium chloride, glycidyl (meth) ) Adducts of acrylate and amine compounds.
(Xii) 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.
(Xiii) 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.
(Xiv) Polymerizable unsaturated monomer having a UV-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.
(Xv) 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-tetramethylpiperidine and the like.
(Xvi) 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.
(Xvii) Polymerizable unsaturated monomer having an acid anhydride group: For example, maleic anhydride, itaconic anhydride, citraconic anhydride and the like.

  Especially, when the polymerizable unsaturated monomer (m-2) having a hydrophilic group does not contain 2-hydroxyethyl acrylate, the polymerizable unsaturated monomer (m -3) preferably contains the hydroxyl group-containing polymerizable unsaturated monomer (x) as at least a part thereof. As the hydroxyl group-containing polymerizable unsaturated monomer (x), 2-hydroxyethyl methacrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate are preferable. -Hydroxyethyl methacrylate is more preferred.

  When the polymerizable unsaturated monomer (m-3) contains the hydroxyl group-containing polymerizable unsaturated monomer (x), the content of the hydroxyl group-containing polymerizable unsaturated monomer (x) is that of the monomer component (m). It is suitable to be in the range of 5 to 79% by mass, preferably 10 to 57% by mass, more preferably 15 to 40% by mass, based on the total mass.

Monomer component (m)
In the monomer component (m), the content ratio of the macromonomer (m-1), the polymerizable unsaturated monomer (m-2) having a hydrophilic group and the other polymerizable unsaturated monomer (m-3) is obtained. Monomer component (m) from the viewpoint of increasing the viscosity of the copolymer and improving the smoothness, sharpness, flip-flop properties and water resistance of the coating film formed by the coating material containing the copolymer, and suppressing metallic unevenness Based on the total mass of
Macromonomer (m-1): 1 to 40% by mass, preferably 3 to 29% by mass, more preferably 5 to 15% by mass,
Polymerizable unsaturated monomer having a hydrophilic group (m-2): 5 to 99% by mass, preferably 10 to 97% by mass, more preferably 20 to 95% by mass,
Polymerizable unsaturated monomer (m-3) other than macromonomer (m-1) and polymerizable unsaturated monomer (m-2) having a hydrophilic group: 0 to 94% by mass, preferably 0 to 87% by mass, Preferably it is 0-75 mass%.

  The copolymer of the present invention is usually a graft polymer having a main chain and a side chain, and the polymer in the macromonomer (m-1) forms a side chain portion and has a hydrophilicity as described above. The unsaturated monomer (m-2) and other polymerizable unsaturated monomer (m-3) form the main chain portion.

Production Method of Copolymer The copolymer of the present invention comprises the macromonomer (m-1), a polymerizable unsaturated monomer (m-2) having a hydrophilic group, and other polymerizable compounds blended as necessary. Produced by copolymerizing a monomer component (m) comprising an unsaturated monomer (m-3) by a method known per se, for example, a solution polymerization method in an organic solvent, an emulsion polymerization method in water, or the like. can do. Among these, a solution polymerization method that can be carried out by a relatively easy operation is preferable.

  Examples of the polymerization initiator used when copolymerizing the monomer component (m) include benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert-butyl peroxide, Di-tert-amyl peroxide, tert-butyl peroxy-2-ethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, diisopropylbenzene hydroperoxide, etc. Organic peroxides of: azobisisobutyronitrile, azobis (2,4-dimethylvaleronitrile), azobis (2-methylpropiononitrile), azobis (2-methylbutyronitrite) 4,4′-azobis (4-cyanobutanoic acid), dimethylazobis (2-methylpropionate), azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], azobis {2 -Azo compounds such as methyl-N- [2- (1-hydroxybutyl)]-propionamide}; persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate, and the like. These polymerization initiators can be used alone or in combination of two or more. Moreover, it is good also as a redox initiator by using reducing agents, such as saccharide | sugar, sodium formaldehyde sulfoxylate, and an iron complex, for example as needed to the said polymerization initiator.

  The usage-amount of the said polymerization initiator is 0.01-5 mass parts normally on the basis of 100 mass parts of total mass of a monomer component (m), Preferably it can be 0.1-3 mass parts. The method for adding the polymerization initiator is not particularly limited, and can be appropriately selected according to the type and amount thereof. For example, it may be included in the monomer mixture or the reaction solvent in advance, or may be added all at once during the polymerization, or may be added dropwise.

  Moreover, as a solvent in the solution polymerization method, an organic solvent that is less likely to cause chain transfer to the solvent and is water-soluble is preferable. Examples of such solvents include ester solvents such as ethylene glycol monomethyl ether acetate and diethylene glycol monobutyl ether acetate; ketone solvents such as acetone and methyl ethyl ketone; methanol, ethanol, isopropanol, n-butanol, sec-butanol, and isobutanol. Alcohol solvents such as 1,4-dioxane, tetrahydrofuran, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, propylene glycol dimethyl ether, dipropylene glycol dimethyl ether, and other ether solvents; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether Examples include glycol ether solvents such as Is, it can be used either alone or in combination of two or more. Of these, ether solvents and glycol ether solvents are preferred.

  The amount of the organic solvent used in the polymerization reaction is usually 500 parts by weight or less, preferably 50 to 400 parts by weight, more preferably 100 to 200 parts by weight, based on 100 parts by weight of the total mass of the monomer components (m). It is preferable to be within the range of parts.

  The weight average molecular weight of the copolymer of the present invention is 20 from the viewpoints of thickening of the copolymer obtained and smoothness, sharpness and glitter of the coating film formed by the coating material containing the copolymer. It is suitable that it is in the range of 1,000 to 1,000,000, preferably 50,000 to 600,000, more preferably 100,000 to 400,000.

  In the present specification, the number average molecular weight of the polymer obtained by copolymerization of the monomer component (I) and the macromonomer (m-1) and the weight average molecular weight of the copolymer of the present invention are determined by gel permeation chromatography. It is the value obtained by converting the retention time (retention capacity) measured using the graph (GPC) into the molecular weight of polystyrene by the retention time (retention capacity) of standard polystyrene having a known molecular weight measured under the same conditions.

  Among these, the number average molecular weight of the polymer obtained by copolymerization of the monomer component (I) and the macromonomer (m-1) is “HLC-8120GPC” (trade name, Tosoh Corporation) as a gel permeation chromatograph. Manufactured by using a total of four columns, “TSKgel G4000HXL”, “TSKgel G3000HXL”, “TSKgel G2500HXL” and “TSKgel G2000HXL” (trade names, all manufactured by Tosoh Corporation), Using a differential refractometer, it can be measured under the conditions of mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 mL / min.

  Further, the weight average molecular weight of the copolymer of the present invention is determined by using “HLC-8120GPC” (trade name, manufactured by Tosoh Corporation) as a gel permeation chromatograph apparatus, and “TSKgel GMHHR-L” (product) as a column. Name, manufactured by Tosoh Corporation), using a differential refractometer as a detector, mobile phase: dimethylformamide (containing 10 mM each of lithium bromide and phosphoric acid), measurement temperature: 25 ° C., flow rate: It can be measured under the condition of 1 mL / min.

II. The aqueous coating composition of the present invention The copolymer of the present invention has a viscosity characteristic that the viscosity is high and the viscosity decreases with an increase in the shear rate. Therefore, the copolymer of the present invention is suitably used as a viscosity modifier for an aqueous coating. be able to. Among these, a water-based paint containing a surfactant also has a viscosity characteristic in which the viscosity develops and the viscosity decreases with increasing shear rate. For this reason, the aqueous coating material containing the copolymer of the present invention can form a coating film having excellent smoothness and sharpness. Moreover, according to the water-based paint of the present invention, it is possible to form a coating film having excellent glitter with high flip-flop properties and suppressed metallic unevenness.

  The aqueous coating composition according to the present invention (hereinafter sometimes abbreviated as “present coating”) usually contains the copolymer and the film-forming resin (A).

Film-forming resin (A)
As the film-forming resin (A), a water-soluble or water-dispersible film-forming resin known per se that has been conventionally used as a binder component of water-based paints can be used. Examples of the film-forming resin (A) include acrylic resin, polyester resin, alkyd resin, silicon resin, fluororesin, epoxy resin, and polyurethane resin.

  Of these, a film-forming resin (A) having high smoothness, sharpness, flip-flop properties, excellent appearance with suppressed metallic unevenness, and excellent water resistance can be formed. ) Is preferably a water-dispersible film-forming resin. A water-dispersible film-forming resin is generally obtained by dispersing a relatively hydrophobic film-forming resin in an aqueous medium, and therefore, compared with a water-soluble film-forming resin imparted with high hydrophilicity. A coating film excellent in water resistance is formed. In addition, since the copolymer of the present invention has a relatively high molecular weight side chain, it forms a network structure with the relatively hydrophobic film-forming resin as described above, and develops a viscosity, so that it has smoothness, freshness, It is possible to form a coating film having excellent visual appearance and high flip-flop properties and excellent metallic unevenness.

  The water-dispersible film-forming resin is preferably a film-forming resin provided with water dispersibility by a surfactant from the viewpoint of the storage stability of the resulting coating. The copolymer of the present invention has a viscosity characteristic that develops viscosity even in a water-based paint containing a surfactant and decreases with increasing shear rate. A water-based coating composition containing a film-forming resin imparted with water dispersibility by an agent is excellent in storage stability, smoothness, sharpness and flip-flop properties, and excellent in metallic unevenness. It is possible to form a coating film having an excellent appearance and excellent water resistance.

  As the film-forming resin imparted with water dispersibility by the surfactant, for example, an acrylic resin produced by an emulsion polymerization method using a surfactant can be suitably used.

  The film-forming resin (A) is preferably a resin having an ester bond from the viewpoint of the smoothness, sharpness, flip-flop properties, and metallic unevenness of the coating film to be formed. As the resin having an ester bond, for example, a copolymer obtained by polymerizing a monomer mixture containing a polymerizable unsaturated monomer having an ester bond, an acrylic resin, a polyester resin, and the like can be preferably used. However, acrylic resin is preferred. The aqueous coating composition containing the copolymer of the present invention and a film-forming resin having an ester bond has high smoothness, sharpness and flip-flop properties, and has an excellent appearance with suppressed metallic unevenness. The reason why a coating film can be formed is the affinity between the ester bond in the polymerizable unsaturated monomer (a) present in the side chain of the copolymer of the present invention and the ester bond in the film-forming resin (A). It is presumed that a high viscosity is developed because a network structure is formed that is high and is bonded more firmly.

  Moreover, it is preferable that film forming resin (A) has crosslinkable functional groups, such as a hydroxyl group, a carboxyl group, and an epoxy group.

  The aqueous coating composition of the present invention preferably further contains a curing agent (B) described later. When the aqueous coating composition of the present invention contains a curing agent (B), the film-forming resin (A) usually has a crosslinkable functional group such as a hydroxyl group, a carboxyl group, an epoxy group, and the curing. A resin (base resin) that can form a cured film by reacting with the agent (B) is used.

  Examples of the base resin include acrylic resin, polyester resin, alkyd resin, and polyurethane resin. Among these, the base resin is preferably a hydroxyl group-containing resin, and more preferably a hydroxyl group-containing acrylic resin (A1) and / or a hydroxyl group-containing polyester resin (A2). Moreover, it is more preferable to use together a hydroxyl-containing acrylic resin (A1) and a hydroxyl-containing polyester resin (A2) from a viewpoint of the smoothness of a coating film formed, a clearness, and the improvement of glitter. Moreover, as a ratio in the case of using together, based on the total amount of a hydroxyl-containing acrylic resin (A1) and a hydroxyl-containing polyester resin (A2), the former is about 20-80 mass%, especially about 30-70 mass%. The latter is preferably about 80 to 20% by mass, particularly about 70 to 30% by mass.

  When the film-forming resin (A) has an acid group such as a carboxyl group, the acid value is preferably about 5 to 150 mgKOH / g, more preferably about 10 to 100 mgKOH / g, More preferably, it is about ˜80 mgKOH / g. When the resin (A) has a hydroxyl group, the hydroxyl value is preferably about 1 to 200 mgKOH / g, more preferably about 2 to 180 mgKOH / g, and about 5 to 170 mgKOH / g. Is more preferable.

Hydroxyl group-containing acrylic resin (A1)
As the hydroxyl group-containing acrylic resin (A1), for example, a hydroxyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer can be obtained by a method known per se, for example, It can be produced by copolymerization by a method such as a solution polymerization method in an organic solvent, an emulsion polymerization method in water, or a miniemulsion polymerization method in water. Among these, when used as a film-forming resin for water-based paints, an emulsion polymerization method in water is preferable because the number of steps required for producing the resin is small.

  The hydroxyl group-containing polymerizable unsaturated monomer is a compound having at least one hydroxyl group and one polymerizable unsaturated bond in one molecule. Examples of the hydroxyl group-containing polymerizable unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, and the like. Monoesterified product of (meth) acrylic acid and C2-C8 dihydric alcohol; ε-caprolactone modified product of monoesterified product of (meth) acrylic acid and C2-C8 dihydric alcohol; A polyoxyalkylene glycol modified product of a monoesterified product of (meth) acrylic acid and a dihydric alcohol having 2 to 8 carbon atoms; N-hydroxymethyl (meth) acrylamide; allyl alcohol; and polyoxy having a hydroxyl group at the molecular end Examples thereof include (meth) acrylate having an ethylene chain. These can be used alone or in combination of two or more.

  Among these, from the viewpoint of improving the smoothness, sharpness, glitter, flip-flop properties, etc. of the coating film to be formed and suppressing metallic unevenness, the hydroxyl group-containing polymerizable unsaturated monomer has a hydroxyl group-containing polymerization having an ester bond. It is preferably a polymerizable unsaturated monomer. Examples of the hydroxyl group-containing polymerizable unsaturated monomer having an ester bond include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and 4-hydroxybutyl (meth) acrylate. A monoesterified product of (meth) acrylic acid and a dihydric alcohol having 2 to 8 carbon atoms, such as a monoesterified product of the (meth) acrylic acid and a dihydric alcohol having 2 to 8 carbon atoms, A polyoxyalkylene glycol modified product of a monoester product of the (meth) acrylic acid and a dihydric alcohol having 2 to 8 carbon atoms. Of these, monoesterified products of (meth) acrylic acid and dihydric alcohols having 2 to 8 carbon atoms are preferred, such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) ) Acrylate and 4-hydroxybutyl (meth) acrylate are more preferred.

  Examples of the other polymerizable unsaturated monomer copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer are exemplified as the (m-2) component and the (m-3) component in the description of the copolymer. Among the polymerizable unsaturated monomers, monomers (i) to (ix) and (xi) to (xvii) that are polymerizable unsaturated monomers other than the hydroxyl group-containing polymerizable unsaturated monomer can be used. These polymerizable unsaturated monomers can be used alone or in combination of two or more.

  The hydroxyl group-containing acrylic resin (A1) preferably has an amide group. The hydroxyl group-containing acrylic resin having an amide group includes, for example, (meth) acrylamide, N, N-dimethylamino as one of other polymerizable unsaturated monomers copolymerizable with the hydroxyl group-containing polymerizable unsaturated monomer. It can be produced by using an amide group-containing polymerizable unsaturated monomer such as propyl (meth) acrylamide, methylene bis (meth) acrylamide, or ethylene bis (meth) acrylamide.

  The proportion of the hydroxyl group-containing polymerizable unsaturated monomer used in the production of the hydroxyl group-containing acrylic resin (A1) is preferably about 1 to 50% by mass, and about 2 to 40% by mass, based on the total amount of monomer components. Is more preferable, and about 3 to 30% by mass is more preferable.

  The hydroxyl group-containing acrylic resin (A1) preferably has an acid value of about 0.1 to 200 mgKOH / g, from the viewpoint of storage stability of the paint, water resistance of the resulting coating film, and 2 to 150 mgKOH / g. More preferably, it is about g, and it is further more preferable that it is about 5-100 mgKOH / g.

  The hydroxyl group-containing acrylic resin (A1) preferably has a hydroxyl value of about 0.1 to 200 mgKOH / g, and about 2 to 150 mgKOH / g, from the viewpoint of water resistance of the resulting coating film. It is more preferable, and it is still more preferable that it is about 5-100 mgKOH / g.

  Moreover, as said hydroxyl-containing acrylic resin (A1), (b-1) 5-70 mass% of hydrophobic polymerizable unsaturated monomers, (b-2) 0.1-25 mass% of hydroxyl-containing polymerizable unsaturated monomers (B-3) 0.1-20% by mass of a carboxyl group-containing polymerizable unsaturated monomer and (b-4) polymerizable unsaturated monomers other than the above polymerizable unsaturated monomers (b-1) to (b-3) Water-dispersible hydroxyl group-containing acrylic resin (A1 ′) having an acid value of 1 to 100 mgKOH / g and a hydroxyl value of 1 to 100 mgKOH / g, obtained by copolymerizing the monomer component (b) comprising 0 to 94.8% by mass of monomers. Can be preferably used.

Hydrophobic polymerizable unsaturated monomer (b-1)
The hydrophobic polymerizable unsaturated monomer (b-1) is a polymerizable unsaturated group having a linear, branched or cyclic saturated or unsaturated hydrocarbon group having 4 or more carbon atoms, preferably 6 to 18 carbon atoms. Monomers having a hydrophilic group such as a hydroxyl group-containing polymerizable unsaturated monomer are excluded. Examples of the monomer include n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, and 2-ethylhexyl. (Meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate, cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t -Alkyl or cycloalkyl (meth) acrylates such as butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, tricyclodecanyl (meth) acrylate Polymerizable unsaturated compounds having an isobornyl group such as isobornyl (meth) acrylate; Polymerizable unsaturated compounds having an adamantyl group such as adamantyl (meth) acrylate; benzyl (meth) acrylate, styrene, α-methylstyrene, vinyltoluene, etc. And aromatic ring-containing polymerizable unsaturated monomers. These monomers can be used alone or in combination of two or more.

  Among these, from the viewpoint of improving the smoothness, sharpness, glitter and water resistance of the resulting coating film, the hydrophobic polymerizable unsaturated monomer (b-1) is n-butyl (meth) acrylate, 2 -It is preferably at least one polymerizable unsaturated monomer selected from the group consisting of ethylhexyl (meth) acrylate and styrene.

Hydroxyl-containing polymerizable unsaturated monomer (b-2)
The hydroxyl group-containing polymerizable unsaturated monomer (b-2) can improve the stability of the obtained water-dispersible hydroxyl group-containing acrylic resin (A1 ′) in an aqueous medium. Further, when a compound having reactivity with a hydroxyl group is used as the curing agent (B) described later, the water-dispersible hydroxyl group-containing acrylic resin (A1 ′) and the curing agent (B) are cross-linked and excellent in water resistance. A coated film can be formed. The above-mentioned thing can be used as a hydroxyl-containing polymerizable unsaturated monomer (b-2).

Carboxyl group-containing polymerizable unsaturated monomer (b-3)
The carboxyl group-containing polymerizable unsaturated monomer (b-3) can improve the stability of the obtained water-dispersible hydroxyl group-containing acrylic resin (A1 ′) in an aqueous medium. In addition, when a compound having reactivity with a carboxyl group is used as the curing agent (B) described later, the water-dispersible hydroxyl group-containing acrylic resin (A1 ′) and the curing agent (B) are cross-linked, resulting in water resistance. An excellent coating film can be formed.

  Examples of the carboxyl group-containing polymerizable unsaturated monomer (b-3) include (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate, and the like. These monomers can be used alone or in combination of two or more.

  Among these, from the viewpoint of stability of the obtained water-dispersible hydroxyl group-containing acrylic resin (A1 ′) in an aqueous medium, the carboxyl group-containing polymerizable unsaturated monomer (b-3) is acrylic acid and / or methacrylic acid. It is preferable that

Polymerizable unsaturated monomers (b-4) other than polymerizable unsaturated monomers (b-1) to (b-3)
The monomer component (b) is added to the hydrophobic polymerizable unsaturated monomer (b-1), the hydroxyl group-containing polymerizable unsaturated monomer (b-2) and the carboxyl group-containing polymerizable unsaturated monomer (b-3), Furthermore, if necessary, polymerizable unsaturated monomers (b-4) other than the polymerizable unsaturated monomers (b-1) to (b-3) can be contained.

  The polymerizable unsaturated monomer (b-4) can be appropriately selected and used depending on the properties desired for the water-dispersible hydroxyl group-containing acrylic resin (A1 ′). Specific examples of the polymerizable unsaturated monomer (b-4) are listed below. These can be used alone or in combination of two or more.

  Examples of the polymerizable unsaturated monomer (b-4) include alkyl having 3 or less carbon atoms such as methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and isopropyl (meth) acrylate ( (Meth) acrylate; (meth) acrylonitrile, (meth) acrylamide, methylenebis (meth) acrylamide, ethylenebis (meth) acrylamide, 2- (methacryloyloxy) ethyltrimethylammonium chloride, adduct of glycidyl (meth) acrylate and amine compound Nitrogen-containing polymerizable unsaturated monomers such as allyl (meth) acrylate, 1,6-hexanediol di (meth) acrylate and other polymerizable unsaturated monomers having at least two polymerizable unsaturated groups in one molecule; glycidyl (Meta) ak , Β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, allyl glycidyl ether Epoxy group-containing polymerizable unsaturated monomers such as: (meth) acrylate having a polyoxyethylene chain whose molecular terminal is an alkoxy group; 2-acrylamido-2-methylpropanesulfonic acid, 2-sulfoethyl (meth) acrylate, allyl sulfone Examples thereof include polymerizable unsaturated monomers having a sulfonic acid group such as acids and 4-styrenesulfonic acid, such as sodium salts and ammonium salts of these sulfonic acids. These monomers can be used alone or in combination of two or more.

In the monomer component (b), the hydrophobic polymerizable unsaturated monomer (b-1), the hydroxyl group-containing polymerizable unsaturated monomer (b-2), the carboxyl group-containing polymerizable unsaturated monomer (b-3) and the polymerizable property The content of the polymerizable unsaturated monomer (b-4) other than the unsaturated monomers (b-1) to (b-3) is the smoothness, sharpness, glitter and water resistance of the formed coating film. From the viewpoint, it is preferable to be within the following range based on the total mass of the monomer component (b).
Hydrophobic polymerizable unsaturated monomer (b-1): 5-70% by mass, preferably 10-65% by mass, more preferably 15-60% by mass,
Hydroxyl group-containing polymerizable unsaturated monomer (b-2): 0.1 to 25% by mass, preferably 0.5 to 15% by mass, more preferably 1 to 10% by mass,
Carboxyl group-containing polymerizable unsaturated monomer (b-3): 0.1 to 20% by mass, preferably 0.5 to 15% by mass, more preferably 1 to 10% by mass,
Polymerizable unsaturated monomers (b-4) other than polymerizable unsaturated monomers (b-1) to (b-3): 0 to 94.8% by mass, preferably 10 to 89% by mass, and more preferably 20 to 20%. 83% by weight.

  The water-dispersible hydroxyl group-containing acrylic resin (A1 ′) includes, for example, the hydrophobic polymerizable unsaturated monomer (b-1), the hydroxyl group-containing polymerizable unsaturated monomer (b-2), and the carboxyl group-containing polymerizable unsaturated monomer. A monomer component (b) comprising a polymerizable unsaturated monomer (b-4) other than (b-3) and polymerizable unsaturated monomers (b-1) to (b-3) is obtained by a method known per se. It can be produced by copolymerization. Specifically, for example, an emulsion polymerization method; a method in which solution polymerization is performed in an organic solvent, and then the obtained copolymer is dispersed in water using a surfactant can be used. Of these, emulsion polymerization is preferred from the viewpoint of improving the stability of the obtained water-dispersible hydroxyl group-containing acrylic resin (A1 ′) in an aqueous medium. The emulsion polymerization method is usually a method in which a polymerizable unsaturated monomer that is insoluble or hardly soluble in water is polymerized in a state of being dispersed in water using a surfactant.

  The water-dispersible hydroxyl group-containing acrylic resin (A1 ′) prepared using the above (b-1) to (b-3) as raw materials has an acid value in the range of 1 to 100 mgKOH / g, and a hydroxyl value of 1 to 1. It is preferably within the range of 100 mgKOH / g. Among these, from the viewpoints of storage stability of the paint, smoothness of the resulting coating film, sharpness, glitter and water resistance, the acid value is more preferably 2 to 50 mgKOH / g, and 5 to 30 mgKOH / g. More preferably, it is g. Further, from the viewpoint of smoothness, sharpness, glitter and water resistance of the resulting coating film, the hydroxyl value is more preferably 2 to 80 mgKOH / g, and further preferably 5 to 60 mgKOH / g. .

  The water-dispersible hydroxyl group-containing acrylic resin (A1 ′) has a core / shell structure from the viewpoint of improving the stability of the obtained water-dispersible hydroxyl group-containing acrylic resin (A1 ′) in an aqueous medium. The core part is preferably crosslinked.

  Among these, from the viewpoint of improving the smoothness, sharpness, glitter and water resistance of the coating film to be formed, the water-dispersible hydroxyl group-containing acrylic resin (A1 ′) has a core / shell type structure, 0.1-30% by mass of a polymerizable unsaturated monomer and a polymerizable unsaturated group having a core part having two or more polymerizable unsaturated groups in one molecule based on the total mass of monomer components constituting the core part Is a copolymer (I) having 70 to 99.9% by mass of a polymerizable unsaturated monomer having 1 per molecule as a monomer component, and in the total amount of monomer components constituting the core portion and the shell portion. The content ratio of each monomer is 5 to 70% by mass of the hydrophobic polymerizable unsaturated monomer (b-1) based on the total mass of the monomer components constituting the core part and the shell part, and the hydroxyl group-containing polymerizable unsaturated monomer. (B-2) 0.1-25 %, 0.1 to 20% by mass of a carboxyl group-containing polymerizable unsaturated monomer (b-3), polymerizable unsaturated monomers other than the polymerizable unsaturated monomers (b-1) to (b-3) (b -4) It is preferable that it is 0-94.8 mass% core-shell type water-dispersible acrylic resin (A1'-1).

  In the core-shell type water-dispersible acrylic resin (A1′-1), a polymerizable unsaturated monomer having two or more polymerizable unsaturated groups used as a monomer for the core copolymer (I) in one molecule As, for example, allyl (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, tri Methylolpropane tri (meth) acrylate, 1,4-butanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, methylene bis (meth) acrylamide, ethylene bis ( (Meth) acrylamide, penta Rithritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethane di (meth) acrylate, 1,1,1-trishydroxymethylethanetri (meta) ) Acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, triallyl isocyanurate, diallyl terephthalate, divinylbenzene and the like. These monomers can be used alone or in combination of two or more. These monomers can be used alone or in combination of two or more.

  The polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule has a function of imparting a crosslinked structure to the core copolymer (I). The proportion of the polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule can be appropriately determined according to the degree of crosslinking of the core copolymer (I). 0.1-30, based on the total amount of the polymerizable unsaturated monomer having two or more unsaturated groups in one molecule and the polymerizable unsaturated monomer having one polymerizable unsaturated group in one molecule described later The content is preferably mass%, more preferably 0.5 to 10 mass%, and even more preferably 1 to 7 mass%.

  In the core-shell type water-dispersible acrylic resin (A1′-1), the polymerizable unsaturated monomer having one polymerizable unsaturated group in one molecule used as a monomer for the core copolymer (I) is A polymerizable unsaturated monomer copolymerizable with a polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule.

  Specific examples of the polymerizable unsaturated monomer having one polymerizable unsaturated group per molecule include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, and isopropyl (meth). Acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl ( (Meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, "isostearyl acrylate" (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), cyclohexyl (meth) acrylate, methylcyclohexyl (meth) Alkylates such as acrylate, tert-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, and tricyclodecanyl (meth) acrylate, or cycloalkyl (meth) acrylate; polymerizable having an isobornyl group such as isobornyl (meth) acrylate Unsaturated monomer; polymerizable unsaturated monomer having an adamantyl group such as adamantyl (meth) acrylate; polymerizable unsaturated monomer having a tricyclodecenyl group such as tricyclodecenyl (meth) acrylate; benzyl (meth) Aromatic ring-containing polymerizable unsaturated monomers such as acrylate, styrene, α-methylstyrene, vinyltoluene; vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, γ- (meth) acryl Polymerizable unsaturated monomers having alkoxysilyl groups such as yloxypropyltrimethoxysilane and γ- (meth) acryloyloxypropyltriethoxysilane; such as perfluorobutylethyl (meth) acrylate and perfluorooctylethyl (meth) acrylate Perfluoroalkyl (meth) acrylate; polymerizable unsaturated monomer having a fluorinated alkyl group such as fluoroolefin; polymerizable unsaturated monomer having a photopolymerizable functional group such as maleimide group; N-vinylpyrrolidone, ethylene, butadiene, Vinyl compounds such as chloroprene, vinyl propionate and vinyl acetate; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl Monoesterified product of (meth) acrylic acid such as til (meth) acrylate and dihydric alcohol having 2 to 8 carbon atoms, ε-caprolactone modified product of the monoesterified product, N-hydroxymethyl (meth) acrylamide, allyl alcohol Hydroxyl group-containing polymerizable unsaturated monomers such as (meth) acrylate having a polyoxyethylene chain having a hydroxyl group at the molecular end; carboxyl group containing such as (meth) acrylic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate Polymerizable unsaturated monomer; (meth) acrylonitrile, (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide , Glycidyl (meth) acrylate and Nitrogen-containing polymerizable unsaturated monomers such as adducts with amine compounds; glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl Epoxy group-containing polymerizable unsaturated monomers such as (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and allyl glycidyl ether; (meth) acrylate having a polyoxyethylene chain whose molecular terminal is an alkoxy group Can be mentioned. These monomers can be used alone or in combination of two or more according to the performance required for the core-shell type water-dispersible acrylic resin (A1′-1).

  In addition, as the polymerizable unsaturated monomer having one polymerizable unsaturated group per molecule, a polymerizable unsaturated monomer having a C 1 or 2 alkyl group may be used as at least a part thereof. preferable.

  Examples of the polymerizable unsaturated monomer having an alkyl group having 1 or 2 carbon atoms include methyl acrylate, methyl methacrylate, ethyl acrylate, and ethyl methacrylate. These monomers can be used alone or in combination of two or more.

  When the polymerizable unsaturated monomer having one polymerizable unsaturated group per molecule contains the polymerizable unsaturated monomer having an alkyl group having 1 or 2 carbon atoms, the alkyl group having 1 or 2 carbon atoms is The proportion of the polymerizable unsaturated monomer used is determined from the viewpoint of smoothness, sharpness and glitter of the resulting coating film, and the polymerizable unsaturated monomer and polymer having two or more polymerizable unsaturated groups in one molecule Based on the total amount of polymerizable unsaturated monomers having one polymerizable unsaturated group per molecule, 20 to 99.9% by mass, preferably 30 to 99.5% by mass, more preferably 40 to 99% by mass. It is preferable to be within the range.

  The core-shell type water-dispersible acrylic resin (A1′-1) can generally have an average particle diameter in the range of about 10 to 1,000 nm, particularly about 20 to 500 nm.

  In this specification, the average particle size of the core-shell type water-dispersible acrylic resin (A1′-1) is diluted with deionized water by a conventional method using a dynamic light scattering particle size distribution analyzer. From the value measured at 20 ° C. 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 order to improve the mechanical stability of the particles of the core-shell type water-dispersible acrylic resin (A1′-1), acid groups such as carboxyl groups of the water-dispersible acrylic resin are neutralized with a neutralizing agent. It is desirable. The neutralizing agent is not particularly limited as long as it can neutralize an acid group. For example, sodium hydroxide, potassium hydroxide, trimethylamine, 2- (dimethylamino) ethanol, 2-amino-2-methyl- Examples include 1-propanol, triethylamine, and aqueous ammonia. These neutralizing agents are desirably used in such an amount that the pH of the aqueous dispersion of the water-dispersible acrylic resin after neutralization is about 6.5 to 9.0.

  In addition, the core-shell type water-dispersible acrylic resin (A1′-1) contains a polymerizable unsaturated group from the viewpoint of improving the smoothness, sharpness, glitter and water resistance of the coating film to be formed. 0.1 to 30% by mass of a polymerizable unsaturated monomer having two or more in one molecule and 70 to 99.9% by mass of a polymerizable unsaturated monomer having one polymerizable unsaturated group in one molecule are monomer components. Copolymer core (I), hydrophobic polymerizable unsaturated monomer (b-1) 5 to 80% by mass, hydroxyl group-containing polymerizable unsaturated monomer (b-2) 0.1 to 50% by mass , Carboxyl group-containing polymerizable unsaturated monomer (b-3) 0.1 to 50% by mass and polymerizable unsaturated monomers other than the above polymerizable unsaturated monomers (b-1) to (b-3) (b-4) ) Shell which is a copolymer (II) having 0 to 94.8% by mass as a monomer component And the solid content mass ratio of the copolymer (I) to the copolymer (II) is in the range of copolymer (I) / copolymer (II) = 5/95 to 95/5 The core-shell type water-dispersible acrylic resin (A1′-2) is preferable. Especially, the ratio of copolymer (I) / copolymer (II) is 50 by solid content mass ratio from a viewpoint of the smoothness of a coating film to be formed, sharpness, brightness, and water resistance improving. / 50 to 85/15 is preferable, and 65/35 to 80/20 is more preferable.

  In the core-shell type water-dispersible acrylic resin (A1′-2), the use ratio of the polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule in the core portion is the core copolymer. Although it can be suitably determined according to the degree of crosslinking in (I), usually one polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule and one polymerizable unsaturated group in one molecule. It is preferably 0.1 to 30% by mass, more preferably 0.5 to 10% by mass, and further preferably 1 to 7% by mass, based on the total amount of polymerizable unsaturated monomers having. preferable.

In the core-shell type water-dispersible acrylic resin (A1′-2), the hydrophobic polymerizable unsaturated monomer (b-1), the hydroxyl group-containing polymerizable unsaturated monomer (b-2), and the carboxyl group-containing in the shell portion The content of the polymerizable unsaturated monomer (b-3) and the polymerizable unsaturated monomer (b-4) other than the polymerizable unsaturated monomers (b-1) to (b-3) is stable in an aqueous medium. From the viewpoint of excellent properties and smoothness, sharpness, glitter and water resistance of the resulting coating film, it is preferable to be within the following range on the basis of the total mass of the monomer components constituting the shell portion.
Hydrophobic polymerizable unsaturated monomer (b-1): 5 to 80% by mass, preferably 7 to 70% by mass, more preferably 8 to 65% by mass,
Hydroxyl group-containing polymerizable unsaturated monomer (b-2): 0.1 to 50% by mass, preferably 4 to 25% by mass, more preferably 7 to 19% by mass,
Carboxyl group-containing polymerizable unsaturated monomer (b-3): 0.1 to 50% by mass, preferably 5 to 25% by mass, more preferably 7 to 19% by mass,
Polymerizable unsaturated monomers (b-4) other than polymerizable unsaturated monomers (b-1) to (b-3): 0 to 94.8% by mass, preferably 10 to 84% by mass, and more preferably 15 to 78% by weight.

  Moreover, as another polymerizable unsaturated monomer used as a monomer for the shell copolymer (II), 1 is a polymerizable unsaturated group from the viewpoint of improving the smoothness, sharpness and glitter of the resulting coating film. It is preferable not to use a polymerizable unsaturated monomer having two or more in the molecule and to make the copolymer (II) uncrosslinked.

  The core-shell type water-dispersible acrylic resin (A1′-2) is, for example, 0.1 to 30% by mass of a polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule, After emulsion polymerization of a monomer mixture composed of 70 to 99.9% by mass of a polymerizable unsaturated monomer having one saturated group in one molecule to obtain an emulsion of the core copolymer (I), , Hydrophobic polymerizable unsaturated monomer (b-1) 5-80% by mass, hydroxyl group-containing polymerizable unsaturated monomer (b-2) 0.1-50% by mass, carboxyl group-containing polymerizable unsaturated monomer (b- 3) A monomer mixture comprising 0.1 to 50% by mass and 0 to 94.8% by mass of the polymerizable unsaturated monomer (b-4) other than the polymerizable unsaturated monomers (b-1) to (b-3). And further emulsion polymerization to It can be obtained by preparing coalescing (II).

  Emulsion polymerization for preparing an emulsion of the core copolymer (I) can be performed by a conventionally known method. For example, it can be carried out by emulsion polymerization of the monomer mixture using a polymerization initiator in the presence of a surfactant.

  As the surfactant, an anionic surfactant and a nonionic surfactant are suitable. Examples of the anionic surfactant include sodium salts and ammonium salts such as alkylsulfonic acid, alkylbenzenesulfonic acid, and alkylphosphoric acid. Examples of nonionic surfactants include polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene phenyl ether, polyoxyethylene nonyl phenyl ether, Polyoxyethylene octyl phenyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, etc. Is mentioned.

  Also, a polyoxyalkylene group-containing anionic surfactant having an anionic group and a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group in one molecule; an anionic group and radical polymerizability in one molecule A reactive anionic surfactant having an unsaturated group can also be used. Of these, it is preferable to use a reactive anionic surfactant.

  Examples of the reactive anionic surfactant include sodium salts of sulfonic acid compounds having radically polymerizable unsaturated groups such as allyl group, methallyl group, (meth) acryloyl group, propenyl group, butenyl group, An ammonium salt etc. can be mentioned. Among these, an ammonium salt of a sulfonic acid compound having a radically polymerizable unsaturated group is preferable because the resulting coating film is excellent in water resistance. Examples of the commercially available ammonium salt of the sulfonic acid compound include “Latemul S-180A” (trade name, manufactured by Kao Corporation).

  Of the ammonium salts of sulfonic acid compounds having radically polymerizable unsaturated groups, ammonium salts of sulfonic acid compounds having radically polymerizable unsaturated groups and polyoxyalkylene groups are more preferred. Examples of commercially available ammonium salts of sulfonic acid compounds having a radical polymerizable unsaturated group and a polyoxyalkylene group include “AQUALON KH-10” (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), “Latemul PD- 104 ”(trade name, manufactured by Kao Corporation),“ ADEKA rear soap SR-1025 ”(trade name, manufactured by ADEKA), and the like.

  The amount of the surfactant used is preferably 0.1 to 15% by mass, more preferably 0.5 to 10% by mass, and further 1 to 5% by mass based on the total amount of all monomers used. preferable.

  Examples of the polymerization initiator include benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert-butyl peroxide, di-tert-amyl peroxide, and tert-butyl peroxide. Organic peroxides such as 2-ethylhexanoate, tert-butyl peroxylaurate, tert-butyl peroxyisopropyl carbonate, tert-butyl peroxyacetate, diisopropylbenzene hydroperoxide; azobisisobutyronitrile, Azobis (2,4-dimethylvaleronitrile), azobis (2-methylpropiononitrile), azobis (2-methylbutyronitrile), 4,4′-azobis (4-cyanobutyl) Acid), dimethylazobis (2-methylpropionate), azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], azobis {2-methyl-N- [2- (1-hydroxy Butyl)]-propionamide}; persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate, and the like. These polymerization initiators can be used alone or in combination of two or more. Moreover, it is good also as a redox initiator by using together with reducing agents, such as saccharide | sugar, sodium formaldehyde sulfoxylate, and an iron complex, as needed to the said polymerization initiator.

  Generally the usage-amount of the said polymerization initiator is 0.1-5 mass% on the basis of the total mass of all the monomers used, and 0.2-3 mass% is more preferable. The method for adding the polymerization initiator is not particularly limited, and can be appropriately selected according to the type and amount thereof. For example, it may be previously contained in the monomer mixture or the aqueous medium, or may be added all at once during the polymerization, or may be added dropwise.

  The core-shell type water-dispersible acrylic resin (A1′-2) is obtained by adding a hydrophobic polymerizable unsaturated monomer (b-1) and a hydroxyl group-containing polymerizable polymer to the emulsion of the core copolymer (I) obtained above. A polymerizable unsaturated monomer (b-) other than the unsaturated monomer (b-2), the carboxyl group-containing polymerizable unsaturated monomer (b-3), and the polymerizable unsaturated monomers (b-1) to (b-3). It can be obtained by adding the monomer mixture comprising 4) and further polymerizing to form the shell copolymer (II).

  The monomer mixture forming the shell part copolymer (II) can appropriately contain components such as the polymerization initiator, a chain transfer agent, a reducing agent, and a surfactant as necessary. The monomer mixture can be dropped as it is, but it is desirable to drop the monomer mixture as a monomer emulsion obtained by dispersing the monomer mixture in an aqueous medium. In this case, the particle size of the monomer emulsion is not particularly limited.

  As a polymerization method of the monomer mixture for forming the shell copolymer (II), for example, the monomer mixture or an emulsion thereof is dripped in a batch or gradually, and an emulsion of the core copolymer (I) is obtained. And a method of heating to an appropriate temperature while stirring.

  The core-shell type water-dispersible acrylic resin (A1′-2) thus obtained has a polymerizable unsaturated monomer having two or more polymerizable unsaturated groups in one molecule and a polymerizable unsaturated group in one molecule. A copolymer (I) of a monomer mixture comprising one polymerizable unsaturated monomer as a core part, a hydrophobic polymerizable unsaturated monomer (b-1), a hydroxyl group-containing polymerizable unsaturated monomer (b-2), Copolymerization of a monomer mixture comprising a carboxyl group-containing polymerizable unsaturated monomer (b-3) and a polymerizable unsaturated monomer (b-4) other than the polymerizable unsaturated monomers (b-1) to (b-3). It has a multi-layer structure with the union (II) as a shell part.

Hydroxyl-containing polyester resin (A2)
In the aqueous coating composition of the present invention, the coating film performance such as smoothness, sharpness, and water resistance of the coating film obtained by using the hydroxyl group-containing polyester resin (A2) as the film-forming resin (A). Can be improved.

  The hydroxyl group-containing polyester resin (A2) can be usually produced by an esterification reaction or an ester exchange reaction between an acid component and an alcohol component.

  As said acid component, the compound normally used as an acid component can be used at the time of manufacture of a polyester resin. Examples of the acid component include an aliphatic polybasic acid, an alicyclic polybasic acid, an aromatic polybasic acid, and the like.

  The aliphatic polybasic acid is generally an aliphatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aliphatic compound, and an esterified product of the aliphatic compound. Examples of the aliphatic polybasic acid include succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid, brassic acid, octadecanedioic acid, citric acid, butane. Aliphatic polyvalent carboxylic acids such as tetracarboxylic acid; anhydrides of the aliphatic polyvalent carboxylic acids; and esterified products of lower alkyl having about 1 to 4 carbon atoms of the aliphatic polyvalent carboxylic acids. The above aliphatic polybasic acids can be used alone or in combination of two or more.

  As the aliphatic polybasic acid, it is particularly preferable to use adipic acid and / or adipic anhydride from the viewpoints of smoothness and sharpness of the resulting coating film.

  The alicyclic polybasic acid is generally a compound having one or more alicyclic structures and two or more carboxyl groups in one molecule, an acid anhydride of the compound, and an esterified product of the compound. The alicyclic structure is mainly a 4- to 6-membered ring structure. Examples of the alicyclic polybasic acid include 1,2-cyclohexanedicarboxylic acid, 1,3-cyclohexanedicarboxylic acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 3-methyl- Alicyclic polycarboxylic acids such as 1,2-cyclohexanedicarboxylic acid, 4-methyl-1,2-cyclohexanedicarboxylic acid, 1,2,4-cyclohexanetricarboxylic acid, 1,3,5-cyclohexanetricarboxylic acid; An anhydride of an alicyclic polyvalent carboxylic acid; an esterified product of a lower alkyl having about 1 to 4 carbon atoms of the alicyclic polyvalent carboxylic acid. The said alicyclic polybasic acid can be used individually or in combination of 2 or more types.

  Examples of the alicyclic polybasic acid include 1,2-cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic anhydride, 1,3-cyclohexanedicarboxylic acid, from the viewpoint of smoothness and sharpness of the resulting coating film. It is preferable to use an acid, 1,4-cyclohexanedicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic acid, 4-cyclohexene-1,2-dicarboxylic anhydride, and among them, 1,2-cyclohexanedicarboxylic acid and More preferably, 1,2-cyclohexanedicarboxylic anhydride is used.

  The aromatic polybasic acid is generally an aromatic compound having two or more carboxyl groups in one molecule, an acid anhydride of the aromatic compound, and an esterified product of the aromatic compound, for example, phthalic acid , Isophthalic acid, terephthalic acid, naphthalenedicarboxylic acid, 4,4′-biphenyldicarboxylic acid, trimellitic acid, pyromellitic acid and other aromatic polycarboxylic acids; anhydrides of the aromatic polycarboxylic acids; aromatics Examples thereof include esterified products of lower alkyl having about 1 to 4 carbon atoms of polyvalent carboxylic acid. The aromatic polybasic acids can be used alone or in combination of two or more.

  As the aromatic polybasic acid, it is preferable to use phthalic acid, phthalic anhydride, isophthalic acid, trimellitic acid, or trimellitic anhydride.

  Moreover, acid components other than the said aliphatic polybasic acid, alicyclic polybasic acid, and aromatic polybasic acid can also be used. Such acid component is not particularly limited, for example, coconut oil fatty acid, cottonseed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, Fatty acids such as castor oil fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid; lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, benzoic acid, p-tert-butylbenzoic acid, cyclohexane Examples thereof include monocarboxylic acids such as acid and 10-phenyloctadecanoic acid; hydroxycarboxylic acids such as lactic acid, 3-hydroxybutanoic acid, and 3-hydroxy-4-ethoxybenzoic acid. These acid components can be used alone or in combination of two or more.

  As said alcohol component, the polyhydric alcohol which has a 2 or more hydroxyl group in 1 molecule can be used conveniently. Examples of the polyhydric alcohol include ethylene glycol, propylene glycol, diethylene glycol, trimethylene glycol, tetraethylene glycol, triethylene glycol, dipropylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3 -Butanediol, 1,2-butanediol, 2-methyl-1,3-propanediol, 3-methyl-1,2-butanediol, 2-butyl-2-ethyl-1,3-propanediol, 1, 2-pentanediol, 1,5-pentanediol, 1,4-pentanediol, 2,4-pentanediol, 2,3-dimethyltrimethylene glycol, tetramethylene glycol, 3-methyl-4,3-pentanediol, 3-methyl-1,5-pentanediol, 2, , 4-trimethyl-1,3-pentanediol, 1,6-hexanediol, 1,5-hexanediol, 1,4-hexanediol, 2,5-hexanediol, neopentyl glycol, 1,4-cyclohexanedi Dihydric alcohols such as methanol, tricyclodecane dimethanol, hydroxypivalic acid neopentyl glycol ester, hydrogenated bisphenol A, hydrogenated bisphenol F, and dimethylolpropionic acid; lactone compounds such as ε-caprolactone in these dihydric alcohols Added polylactone diol; ester diol compound such as bis (hydroxyethyl) terephthalate; alkylene oxide adduct of bisphenol A, polyether such as polyethylene glycol, polypropylene glycol, polybutylene glycol Terdiol compounds; glycerin, trimethylolethane, trimethylolpropane, diglycerin, triglycerin, 1,2,6-hexanetriol, pentaerythritol, dipentaerythritol, tris (2-hydroxyethyl) isocyanuric acid, sorbitol, mannitol, etc. A trilactone or higher alcohol; a polylactone polyol compound obtained by adding a lactone compound such as ε-caprolactone to the trihydric or higher alcohol; a fatty acid esterified product of glycerin, and the like.

  Moreover, alcohol components other than the said polyhydric alcohol can also be used. The alcohol component is not particularly limited, and examples thereof include monoalcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, stearyl alcohol, and 2-phenoxyethanol; propylene oxide, butylene oxide, “Cardura E10” (trade name, HEXION Specialty) Examples include alcohol compounds obtained by reacting monoepoxy compounds such as Chemicals, Inc. (glycidyl esters of synthetic highly branched saturated fatty acids) and acids.

  The manufacturing method of a hydroxyl-containing polyester resin (A2) is not specifically limited, It can carry out in accordance with a normal method. For example, the acid component and the alcohol component are heated in a nitrogen stream at about 150 to 250 ° C. for about 5 to 10 hours, and a method of performing esterification reaction or transesterification reaction of the acid component and alcohol component is performed. A containing polyester resin can be produced.

  When the acid component and the alcohol component are esterified or transesterified, they may be added to the reaction vessel at one time, or one or both may be added in several portions. . Moreover, after synthesizing a hydroxyl group-containing polyester resin, the resulting hydroxyl group-containing polyester resin may be reacted with an acid anhydride to be half-esterified to obtain a carboxyl group- and hydroxyl group-containing polyester resin. Moreover, after synthesizing a carboxyl group-containing polyester resin, the above alcohol component may be added to obtain a hydroxyl group-containing polyester resin.

  In the esterification or transesterification reaction, as a catalyst for promoting the reaction, dibutyltin oxide, antimony trioxide, zinc acetate, manganese acetate, cobalt acetate, calcium acetate, lead acetate, tetrabutyl titanate, tetraisopropyl A catalyst known per se, such as titanate, can be used.

  The hydroxyl group-containing polyester resin (A2) can be modified with a fatty acid, a monoepoxy compound, a polyisocyanate compound or the like during or after the preparation of the resin.

  Examples of the fatty acid include coconut oil fatty acid, cottonseed oil fatty acid, hemp seed oil fatty acid, rice bran oil fatty acid, fish oil fatty acid, tall oil fatty acid, soybean oil fatty acid, linseed oil fatty acid, tung oil fatty acid, rapeseed oil fatty acid, castor oil fatty acid, dehydrated castor Oil fatty acids, safflower oil fatty acids and the like can be mentioned, and as the above-mentioned monoepoxy compound, for example, “Cardura E10” (trade name, manufactured by HEXION Specialty Chemicals, glycidyl ester of synthetic highly branched saturated fatty acid) is preferably used. it can.

  Examples of the polyisocyanate compound include aliphatic diisocyanate compounds such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, methylcyclohexane-2,4-diisocyanate, and methylcyclohexane-2. , 6-diisocyanate, 4,4'-methylenebis (cyclohexylisocyanate), 1,3- (isocyanatomethyl) cyclohexane and other alicyclic diisocyanate compounds; tolylene diisocyanate, xylylene diisocyanate, diphenylmethane diisocyanate and other aromatic diisocyanate compounds ; Organic polyisocyanates such as triisocyanate and higher polyisocyanates such as lysine triisocyanate Adduct of each of these organic polyisocyanates with polyhydric alcohol, low molecular weight polyester resin, water, etc .; cyclized polymer (for example, isocyanurate) between these organic polyisocyanates, biuret type addition Thing etc. are mentioned. These polyisocyanate compounds can be used alone or in admixture of two or more.

  Further, as the hydroxyl group-containing polyester resin (A2), the content of the alicyclic polybasic acid in the acid component of the raw material is selected from the viewpoint of excellent smoothness, sharpness and water resistance of the obtained coating film. What is about 20-100 mol% is preferable on the basis of the total amount of a component, What is about 25-95 mol% is more preferable, What is about 30-90 mol% is still more preferable. In particular, the viewpoint that the alicyclic polybasic acid is 1,2-cyclohexanedicarboxylic acid and / or 1,2-cyclohexanedicarboxylic acid anhydride is excellent in smoothness, sharpness, etc. of the resulting coating film Therefore, it is preferable.

  The hydroxyl group-containing polyester resin (A2) preferably has a hydroxyl value of about 1 to 200 mgKOH / g, more preferably about 2 to 180 mgKOH / g, and still more preferably about 5 to 170 mgKOH / g. When the hydroxyl group-containing polyester resin (A2) further has a carboxyl group, the acid value is preferably about 5 to 150 mgKOH / g, more preferably about 10 to 100 mgKOH / g. More preferably, it is about 80 mgKOH / g. The number average molecular weight of the hydroxyl group-containing polyester resin (A2) is preferably about 500 to 50,000, more preferably about 1,000 to 30,000, and about 1,200 to 10,000. More preferably.

  The neutralization of the hydroxyl group-containing polyester resin (A2) can be performed using a basic compound. Examples of the basic compound include hydroxides of alkali metals or alkaline earth metals such as sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide; ammonia; ethylamine, propylamine, butylamine , Primary monoamines such as benzylamine, monoethanolamine, 2,2-dimethyl-3-amino-1-propanol, 2-aminopropanol, 2-amino-2-methyl-1-propanol, 3-aminopropanol; Secondary monoamines such as diethylamine, diethanolamine, di-n-propanolamine, di-isopropanolamine, N-methylethanolamine, N-ethylethanolamine; dimethylethanolamine, trimethylamine, triethylamine, triisopropylamine Tertiary monoamines such as methyldiethanolamine and 2- (dimethylamino) ethanol; polyamines such as diethylenetriamine, hydroxyethylaminoethylamine, ethylaminoethylamine, methylaminopropylamine, etc., and these may be used alone or in combination of two or more. Can be used. The basic compound is preferably water-soluble.

  In the aqueous coating composition of the present invention, the amount of the hydroxyl group-containing polyester resin (A2) is usually 2 to 70 parts by weight, preferably 10 to 50 parts by weight, based on 100 parts by weight of the resin solid content in the paint. More preferably, it can be in the range of 15 to 40 parts by mass.

  Examples of the polyurethane resin include at least one diol selected from the group consisting of aliphatic and / or alicyclic diisocyanates, polyether diols, polyester diols, and polycarbonate diols, low molecular weight polyhydroxy compounds, and dimethylol alkanoic acids. A urethane prepolymer is produced by reaction, neutralized with a tertiary amine, emulsified and dispersed in water, and then an aqueous solution containing a chain extender such as polyamine, a crosslinking agent and / or a terminator as necessary. Examples thereof include those obtained by mixing with a medium and reacting until the isocyanate group is substantially eliminated. By the above method, a self-emulsifying type polyurethane resin having an average particle diameter of about 0.001 to about 3 μm can be usually obtained.

  The blending amount of the polyurethane resin in the aqueous coating composition of the present invention is usually 2 to 70 parts by weight, preferably 5 to 50 parts by weight, more preferably, based on 100 parts by weight of the resin solid content in the paint. It can be in the range of 8 to 30 parts by mass.

Curing agent (B)
The curing agent (B) is a compound capable of curing the aqueous coating composition of the present invention by reacting with a functional group such as a hydroxyl group, a carboxyl group, or an epoxy group in the film-forming resin (A). Examples of the curing agent (B) include amino resins, polyisocyanate compounds, blocked polyisocyanate compounds, epoxy group-containing compounds, carboxyl group-containing compounds, carbodiimide group-containing compounds, and the like. Of these, amino resins capable of reacting with hydroxyl groups, polyisocyanate compounds and blocked polyisocyanate compounds; carbodiimide group-containing compounds capable of reacting with carboxyl groups are preferred. Of these, amino resins and blocked polyisocyanate compounds are preferred, and amino resins are more preferred. A hardening | curing agent (B) can be used individually or in combination of 2 or more types.

As said amino resin, the partial methylolation amino resin obtained by reaction of an amino component and an aldehyde component, or a complete methylolation amino resin can be used. Examples of the amino component include melamine, urea, benzoguanamine, acetoguanamine, steroguanamine, spiroguanamine, dicyandiamide and the like. Examples of the aldehyde component include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like.
Moreover, what methylated the methylol group of the said methylolated amino resin partially or completely with suitable alcohol can also be used. Examples of the alcohol used for etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol, and 2-ethylhexanol.

  As the amino resin, a melamine resin is preferable. In particular, methyl ether melamine resins in which methylol groups of partially or fully methylolated melamine resins are partially or completely etherified with methyl alcohol, methylol groups of partially or fully methylolated melamine resins are partially or completely with butyl alcohol. Preferred is a methyl-butyl mixed etherified melamine resin in which the methylol group of a partially or completely methylolated melamine resin is partially or completely etherified with methyl alcohol and butyl alcohol. Etherified melamine resins are more preferred.

  The melamine resin preferably has a weight average molecular weight of about 400 to 6,000, more preferably about 800 to 5,000, and still more preferably about 1,000 to 4,000. Most preferably, it is about 1,200 to 3,000.

  In the present specification, the number-average molecular weight and the weight-average molecular weight of the film-forming resin (A) and the curing agent (B) are measured using a gel permeation chromatograph (GPC). Is a value obtained by converting the molecular weight of polystyrene based on 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, 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.

  A commercially available product can be used as the melamine resin. Examples of commercially available product names include “Cymel 202”, “Cymel 203”, “Cymel 238”, “Cymel 251”, “Cymel 303”, “Cymel 323”, “Cymel 324”, “Cymel 325”, “Cymel 327”, “Cymel 350”, “Cymel 385”, “Cymel 1156”, “Cymel 1158”, “Cymel 1116”, “Cymel 1130” (above, made by Nippon Cytec Industries, Inc.), “Uban 120”, “ “Uban 20HS”, “Uban 20SE60”, “Uban 2021”, “Uban 2028”, “Uban 28-60” (manufactured by Mitsui Chemicals, Inc.), and the like.

  In the aqueous coating composition of the present invention, a hydroxyl group-containing acrylic resin (A1) such as a core-shell type water-dispersible hydroxyl group-containing acrylic resin (A1′-1) is used as the film-forming resin (A). In addition, it is possible to use a melamine resin having a weight average molecular weight of about 1,000 to 4,000, particularly about 1,200 to 3,000, as the curing agent (B), so that the resulting coating film has flip-flop properties and water resistance. From the viewpoint of excellent properties, it is preferable.

  When a melamine resin is used as the curing agent (B), sulfonic acids such as paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid; monobutyl phosphoric acid, dibutyl phosphoric acid, mono 2-ethylhexyl phosphoric acid, Alkyl phosphate esters such as di-2-ethylhexyl phosphate; salts of these acids with amine compounds, etc. can be used as catalysts.

  The blocked polyisocyanate compound is a compound obtained by blocking an isocyanate group of a polyisocyanate compound having at least two isocyanate groups in one molecule with a blocking agent. Examples of the blocking agent include phenols such as phenol, cresol, xylenol, nitrophenol, ethylphenol, hydroxydiphenyl, butylphenol, isopropylphenol, nonylphenol, octylphenol, and methyl hydroxybenzoate; ε-caprolactam, δ-valerolactam, lactams such as γ-butyrolactam, β-propiolactam; aliphatic alcohols such as methanol, ethanol, propyl alcohol, butyl alcohol, amyl alcohol, lauryl alcohol; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono Butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene Ether systems such as glycol monomethyl ether and methoxymethanol; benzyl alcohol, glycolic acid, methyl glycolate, ethyl glycolate, butyl glycolate, lactic acid, methyl lactate, ethyl lactate, butyl lactate, methylol urea, methylol melamine, diacetone alcohol, Alcohols such as 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate; oximes such as formamide oxime, acetamide oxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime; dimethyl malonate, diethyl malonate, Active methylenes such as ethyl acetoacetate, methyl acetoacetate, acetylacetone; butyl mercaptan, t-butyl mercaptan Mercaptans such as hexyl mercaptan, t-dodecyl mercaptan, 2-mercaptobenzothiazole, thiophenol, methylthiophenol, ethylthiophenol; acetanilide, acetanisidide, acetolide, acrylamide, methacrylamide, acetic acid amide, stearamide, benzamide, etc. Acid amides; succinimides, phthalic acid imides, maleic acid imides, etc. imides; System: Imidazoles such as imidazole and 2-ethylimidazole; urea, thiourea, ethylene urea, ethylene thiourea, diphenyl urea N- phenylcarbamate ester of carbamic acid such as phenyl; ethyleneimine, imine and propylene imine; urea in sodium bisulfite, sulfite, such as bisulfite potassium; compounds such azole systems. Examples of the azole compounds include pyrazole, 3,5-dimethylpyrazole, 3-methylpyrazole, 4-benzyl-3,5-dimethylpyrazole, 4-nitro-3,5-dimethylpyrazole, 4-bromo-3, Pyrazole or pyrazole derivatives such as 5-dimethylpyrazole and 3-methyl-5-phenylpyrazole; Imidazole or imidazole derivatives such as imidazole, benzimidazole, 2-methylimidazole, 2-ethylimidazole and 2-phenylimidazole; 2-methylimidazoline And imidazoline derivatives such as 2-phenylimidazoline.

  Examples of the polyisocyanate compound having at least two isocyanate groups in one molecule include aliphatic diisocyanate compounds such as hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and lysine diisocyanate; hydrogenated xylylene diisocyanate, cyclohexane. Cycloaliphatic diisocyanate compounds such as silylene diisocyanate and isophorone diisocyanate; aromatic diisocyanate compounds such as tolylene diisocyanate, phenylene diisocyanate, 4,4′-diphenylmethane diisocyanate, xylylene diisocyanate, tetramethylxylylene diisocyanate, naphthalene diisocyanate; Natoethyl-2,6-diisocyanatocaproe Trivalent or higher organic polyisocyanate compounds such as 3-isocyanatomethyl-1,6-hexamethylene diisocyanate and 4-isocyanatomethyl-1,8-octamethylene diisocyanate (commonly known as triaminononane triisocyanate); Examples include dimers or trimers of polyisocyanate compounds; prepolymers obtained by subjecting these polyisocyanate compounds and polyhydric alcohols, low molecular weight polyester resins, or water to urethanization under conditions of excess isocyanate groups.

  As said carbodiimide group containing compound, what made the carbon dioxide reaction of the isocyanate groups of the said polyisocyanate compound can be used, for example. As the carbodiimide group-containing compound, it is preferable to use a polycarbodiimide compound having at least two carbodiimide groups in one molecule.

  As the polycarbodiimide compound, it is preferable to use a water-soluble or water-dispersible polycarbodiimide compound from the viewpoints of smoothness and sharpness of the resulting coating film. As the water-soluble or water-dispersible polycarbodiimide compound, any polycarbodiimide compound that can be stably dissolved or dispersed in an aqueous medium can be used without particular limitation.

  Specific examples of the water-soluble polycarbodiimide compound include “Carbodilite SV-02”, “Carbodilite V-02”, “Carbodilite V-02-L2”, and “Carbodilite V-04” (all manufactured by Nisshinbo Co., Ltd.). , Product name), etc. can be used. Moreover, as said water dispersible polycarbodiimide compound, "Carbodilite E-01", "Carbodilite E-02" (all are the Nisshinbo Co., Ltd. make, brand name) etc. can be used, for example.

  The said polycarbodiimide compound can be used individually or in combination of 2 or more types, respectively.

  The blending ratio of the film-forming resin (A) and the curing agent (B) in the aqueous coating composition according to the present invention is the sum of both from the viewpoints of smoothness of the coating film, sharpness, and water resistance improvement. Based on the amount, the former is about 30 to 95% by mass, preferably about 50 to 90% by mass, more preferably about 60 to 80% by mass, and the latter is about 5 to 70% by mass, preferably 10 to 50% by mass. It is preferable that the amount is about 20 to 40% by mass.

  The curing agent (B) is usually 5 to 60 parts by weight, preferably 10 to 50 parts by weight, more preferably 20 to 40 parts by weight, based on 100 parts by weight of the resin solid content in the paint. It can mix | blend with the water-based coating composition of this.

  When the aqueous coating composition according to the present invention contains the hydroxyl group-containing acrylic resin (A1), the amount of the hydroxyl group-containing acrylic resin (A1) is the total solid content of the film-forming resin (A) and the curing agent (B). It is preferably about 2 to 70% by mass, more preferably about 5 to 55% by mass, and still more preferably about 10 to 40% by mass based on the minute.

  When the aqueous coating composition according to the present invention contains the hydroxyl group-containing polyester resin (A2), the amount of the hydroxyl group-containing polyester resin (A2) is the sum of the film-forming resin (A) and the curing agent (B). The solid content is preferably about 2 to 70% by mass, more preferably about 5 to 55% by mass, and still more preferably about 10 to 40% by mass.

Method for adjusting aqueous coating composition The aqueous coating composition according to the present invention is, for example, a known method using the film-forming resin (A) and the copolymer, and optionally the curing agent (B). Can be prepared by mixing in an aqueous medium and dissolving or dispersing.

  Examples of the aqueous medium include water or a water-organic solvent mixed solution obtained by dissolving a hydrophilic organic solvent in water. Examples of the hydrophilic organic solvent include methyl alcohol, ethyl alcohol, isopropyl alcohol, propylene glycol monopropyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether, dipropylene glycol monomethyl ether, dipropylene glycol mono Examples thereof include butyl ether, tripropylene glycol monomethyl ether, and 3-methyl 3-methoxybutanol. These can be used alone or in combination of two or more. In the water-organic solvent mixed solution, the mixing ratio of water and the organic solvent is not particularly limited, but the content of the organic solvent is about 1 to 50% by mass, preferably about 5 to 35% by mass of the mixed solution. Preferably it is.

  The water-based paint is a term contrasted with an organic solvent-type paint, and generally, a film-forming resin, a pigment, and the like are dispersed and / or dispersed in water or a medium mainly containing water (aqueous medium). It means dissolved paint. When the coating composition of the present invention is a water-based coating, the water content in the coating composition is in the range of 10 to 90 mass%, preferably 20 to 80 mass%, more preferably 30 to 70 mass%. It is preferable that

  In the aqueous coating composition according to the present invention, the blending ratio of the film-forming resin (A) and the copolymer is determined based on the storage stability of the aqueous coating composition, the appearance of the formed coating film, and the coating film performance (water resistance). Etc.) from the viewpoint of the film-forming resin (A) 100 parts by mass, the amount of the copolymer is 0.05 to 30 parts by mass, preferably 0.1 to 20 parts by mass, more preferably It is suitable to be within the range of 0.2 to 10 parts by mass.

  Further, in the aqueous coating composition according to the present invention, the amount of the copolymer is determined from the viewpoints of storage stability of the aqueous coating composition, appearance of the formed coating film, coating film performance (water resistance, etc.), and the like. Based on 100 parts by mass of the aqueous coating composition, 0.01 to 15 parts by mass, preferably 0.05 to 10 parts by mass, and more preferably 0.1 to 5 parts by mass.

When the water-dispersible hydroxyl group-containing acrylic resin (A1 ′) is used as the film-forming resin (A), the aqueous coating composition of the present invention contains the copolymer and the water-dispersible hydroxyl group-containing acrylic resin (A1). ') Can be contained in an amount within the range described below on the basis of 100 parts by mass of the resin solid content in the aqueous coating composition.
Copolymer: 0.05 to 20 parts by mass, preferably 0.1 to 10 parts by mass, more preferably 0.2 to 5 parts by mass,
Water-dispersible hydroxyl group-containing acrylic resin (A1 ′): 2-70 parts by mass, preferably 5-55 parts by mass, more preferably 10-40 parts by mass.
Here, “the resin solid content in the aqueous coating composition” is usually the resin solid content of the copolymer and the water-dispersible hydroxyl group-containing acrylic resin (A1 ′) and, if necessary, the aqueous coating composition of the present invention. It is the total of other resin and solid content of the curing agent (B) added to the product.

  The water-based coating composition of the present invention may further include a glitter pigment, a colored pigment, an extender pigment, a hydrophobic organic solvent, a curing catalyst, an ultraviolet absorber, a light stabilizer, a pigment dispersant, an antifoaming agent, if necessary. Additives for coating materials such as plasticizers, surface conditioners, anti-settling agents and the like can be contained.

  Examples of the bright pigment include aluminum (including vapor-deposited aluminum), copper, zinc, brass, nickel, aluminum oxide, mica, titanium oxide or iron oxide coated with titanium oxide or iron oxide. And mica. These glitter pigments can be used alone or in combination of two or more. These glitter pigments are preferably in the form of flakes. As the bright pigment, aluminum, mica, aluminum oxide coated with titanium oxide or iron oxide, mica coated with titanium oxide or iron oxide is preferable, and aluminum is more preferable.

  The flake-like glitter pigment has a longitudinal dimension of usually about 1 to 100 μm, preferably about 5 to 40 μm, and a thickness of usually about 0.001 to 5 μm, preferably about 0.01 to 2 μm. Can be suitably used.

  When the water-based coating composition of the present invention contains the above-mentioned glitter pigment, it has an advantage that a coating film having high flip-flop properties and excellent glitter with suppressed metallic unevenness can be formed.

  When the water-based paint composition of the present invention contains the above-mentioned glitter pigment, the blending amount of the glitter pigment is usually 1 to 100 mass as a solid content with respect to 100 mass parts of the film-forming resin (A). The amount is preferably about 2 parts by weight, more preferably about 2 to 50 parts by weight, and still more preferably about 3 to 30 parts by weight.

  In addition to the film-forming resin (A), the aqueous coating composition of the present invention can further contain a phosphate group-containing resin as a resin component. In particular, when the aqueous coating composition of the present invention contains the above-mentioned glitter pigment, particularly an aluminum pigment, the aqueous coating composition of the present invention provides smoothness, sharpness, metallic unevenness suppression of the obtained coating film, and From the viewpoint of water resistance, it is preferable to contain a phosphate group-containing resin.

  The phosphoric acid group-containing resin can be produced, for example, by copolymerizing a phosphoric acid group-containing polymerizable unsaturated monomer and other polymerizable unsaturated monomers by a known method such as a solution polymerization method. Examples of the phosphoric acid group-containing polymerizable unsaturated monomer include acid phosphooxyethyl (meth) acrylate, acid phosphooxypropyl (meth) acrylate, a reaction product of glycidyl (meth) acrylate and alkyl phosphoric acid, and the like. . These can be used alone or in combination of two or more.

  In the phosphoric acid group-containing resin, the use ratio when copolymerizing the phosphoric acid group-containing polymerizable unsaturated monomer and the other polymerizable unsaturated monomer is 1/99 to 40 / About 60 is preferable, about 5/95 to 35/65 is more preferable, and about 10/90 to 30/70 is more preferable.

  When the aqueous coating composition of the present invention contains the phosphate group-containing resin, the blending amount of the phosphate group-containing resin is usually 0.5 to 100 parts by mass of the film-forming resin (A). About 15 mass parts is preferable, about 0.75-10 mass parts is more preferable, and about 1-5 mass parts is still more preferable.

  Examples of the color pigment include titanium oxide, zinc white, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigment, phthalocyanine pigment, quinacridone pigment, isoindoline pigment, selenium pigment, and perylene pigment. , Dioxazine pigments, diketopyrrolopyrrole pigments, and the like. These color pigments can be used alone or in combination of two or more.

  When the water-based coating composition of the present invention contains the color pigment, the amount of the color pigment is usually about 1 to 200 parts by mass with respect to 100 parts by mass of the film-forming resin (A) as a solid content. It is preferable that it is about 2-50 mass parts, and it is still more preferable that it is about 3-30 mass parts.

  Examples of the extender pigment include talc, clay, kaolin, barita, barium sulfate, barium carbonate, calcium carbonate, silica, and alumina white.

  When the aqueous coating composition of the present invention contains the above extender, the amount of the extender is usually about 1 to 200 parts by mass with respect to 100 parts by mass of the film-forming resin (A) as a solid content. It is preferable that it is about 2-50 mass parts, and it is still more preferable that it is about 3-30 mass parts.

  As the hydrophobic organic solvent, an organic solvent having a mass dissolved in 100 g of water at 20 ° C. of 10 g or less, preferably 5 g or less, more preferably 1 g or less can be used. Examples of the organic solvent include hydrocarbon solvents such as rubber volatile oil, mineral spirit, toluene, xylene, and solvent naphtha; 1-hexanol, 1-octanol, 2-octanol, 2-ethylhexanol, 1-decanol, and benzyl. Alcohols such as alcohol, ethylene glycol mono 2-ethylhexyl ether, propylene glycol mono n-butyl ether, dipropylene glycol mono n-butyl ether, tripropylene glycol mono n-butyl ether, propylene glycol mono 2-ethylhexyl ether, propylene glycol monophenyl ether Solvent; ester solvents such as n-butyl acetate, isobutyl acetate, isoamyl acetate, methyl amyl acetate, ethylene glycol monobutyl ether; Isobutyl ketone, cyclohexanone, ethyl n- amyl, may be mentioned ketone solvents such as diisobutyl ketone. These can be used alone or in combination of two or more.

  As the hydrophobic organic solvent, an alcohol-based hydrophobic organic solvent is preferable and an alcohol-based hydrophobic organic solvent having 7 to 14 carbon atoms is more preferable from the viewpoint of excellent glitter of the resulting coating film. Among them, at least one selected from the group consisting of 1-octanol, 2-octanol, 2-ethyl-1-hexanol, ethylene glycol mono-2-ethylhexyl ether, propylene glycol mono n-butyl ether, and dipropylene glycol mono n-butyl ether. Alcohol-based hydrophobic organic solvents are preferable, and 2-ethyl-1-hexanol and / or ethylene glycol mono-2-ethylhexyl ether is more preferable.

  When the aqueous coating composition according to the present invention contains the hydrophobic organic solvent, the amount of the hydrophobic organic solvent is 10 to 100 parts by mass based on 100 parts by mass of the solid content in the aqueous coating composition. It is preferably about 15 to 80 parts by mass, more preferably about 20 to 60 parts by mass.

  The solid content of the aqueous coating composition of the present invention is usually preferably about 5 to 70% by mass, more preferably about 15 to 45% by mass, and further about 20 to 35% by mass. preferable.

The aqueous coating composition of the present invention, the change smoothness of the resulting coating film, distinctness of image, from the viewpoint of excellent luster, at a measurement temperature of 20 ° C., a shear rate of from 0.0001Sec ^-1 to 10,000Sec ^-1 It is preferable that the viscosity V _{1 at} 1,000 sec ⁻¹ is 0.1 Pa · sec or less, preferably in the range of 0.01 to 0.1 Pa · sec.

Further, the aqueous coating composition of the present invention, the smoothness of the resulting coating film, distinctness of image, from the viewpoint of excellent luster, at a measurement temperature of 20 ℃, 10,000sec shear rate from 0.0001sec ^{-1 -1} The viscosity V ₂ at 0.1 sec ⁻¹ when the pressure is changed to 30 to 100 Pa · sec, preferably within the range of 35 to 70 Pa · sec.

The viscosity V ₁ and the viscosity V ₂ is able to use a viscoelasticity measuring apparatus measures. As the viscoelasticity measuring device, for example, “HAAKE RheoStress RS150” (trade name, manufactured by HAAKE) or the like can be used.

  The aqueous coating composition containing the copolymer of the present invention has a viscosity characteristic in which the viscosity is high and the viscosity decreases as the shear rate increases. In particular, the aqueous coating composition contains a surfactant. Even in the case where it is contained, the reason is that the polymer present in the side chain of the copolymer of the present invention is a urea bond and / or urethane because it exhibits viscosity and decreases with increasing shear rate. Since it has a bond, a network structure to which a hydrogen bond contributes is formed, a high viscosity is expressed, and the number average molecular weight of the polymer is in a range of 1,000 to 10,000, and a relatively large volume is obtained. Therefore, it is presumed that the network structure is hardly influenced by the surfactant. When the aqueous coating composition contains a resin having an ester bond as the film-forming resin (A), the polymerizable unsaturated monomer (a1) having a urea bond present in the side chain of the copolymer of the present invention. An ester bond in at least one polymerizable unsaturated monomer (a) selected from the group consisting of a polymerizable unsaturated monomer (a2) having a urethane bond and a polymerizable unsaturated monomer (a3) having an imide bond; It is presumed that a high viscosity is developed because a network structure having a high affinity with the ester bond in the film-forming resin (A) and having a stronger bond is formed.

III. Coating method of the present invention The water-based coating composition of the present invention can form a coating film having an excellent appearance by coating on various objects.

The article to be coated to which the aqueous coating composition of the present invention is applied is not particularly limited. Examples of the article to be coated include an outer plate portion of an automobile body such as a passenger car, a truck, a motorcycle, and a bus; an automobile component; an outer plate portion of a household electric product such as a mobile phone and an audio device. Of these, the outer plate portion of the automobile body and the automobile parts are preferable.

  The material of these objects to be coated is not particularly limited. For example, metal materials such as iron, aluminum, brass, copper, tinplate, stainless steel, galvanized steel, zinc alloy (Zn-Al, Zn-Ni, Zn-Fe, etc.) plated steel; polyethylene resin, polypropylene resin, acrylonitrile- Butadiene-styrene (ABS) resin, polyamide resin, acrylic resin, vinylidene chloride resin, polycarbonate resin, polyurethane resin, epoxy resin and other plastic materials such as various FRPs; glass, cement, concrete and other inorganic materials; wood; Examples thereof include fiber materials such as paper and cloth. Of these, metal materials and plastic materials are preferred.

  The object to be coated may be a metal surface of the metal material or a vehicle body formed from the metal material, and may be subjected to surface treatment such as phosphate treatment, chromate treatment, complex oxide treatment, A coating film may be formed thereon.

  As an object to be coated, a surface treatment is applied to the substrate as necessary, an undercoat film is formed thereon, and an intermediate coat film is formed on the undercoat film. Etc. The undercoat coating film is preferably a coating film formed of an electrodeposition paint, preferably a cationic electrodeposition paint.

Coating method After forming a wet coating film (uncured coating film) by applying the aqueous coating composition of the present invention to an object to be coated, the desired coating film can be formed by curing the wet coating film. .

  The coating method of the aqueous coating composition of the present invention is not particularly limited, and examples thereof include air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, and the like. Can be formed. Of these, air spray coating or rotary atomization coating is preferred from the viewpoint of improving the smoothness, sharpness and flip-flop properties of the resulting coating film and suppressing metallic unevenness. Moreover, you may apply electrostatic at the time of coating as needed.

  The coating amount of the water-based coating composition of the present invention is an amount such that the cured film thickness is usually about 1 to 50 μm, preferably about 3 to 50 μm, more preferably about 5 to 35 μm, and still more preferably about 8 to 25 μm. Preferably there is.

  Curing of the wet coating film can be carried out by heating after applying the aqueous coating composition of the present invention to the article to be coated. Heating can be performed by a known heating means. For example, a drying furnace such as a hot air furnace, an electric furnace, or an infrared induction heating furnace can be used. The heating temperature is preferably about 80 to 180 ° C, more preferably about 100 to 170 ° C, and still more preferably about 120 to 160 ° C. The heating time is not particularly limited, but is usually preferably about 10 to 60 minutes, more preferably about 20 to 40 minutes.

  After the application of the aqueous coating composition of the present invention, before performing the above heat curing, from the viewpoint of preventing the occurrence of coating film defects such as armpits, preheating, air blowing, etc. under heating conditions in which the coating film is not substantially cured. Preferably it is done. The preheating temperature is preferably about 40 to 100 ° C, more preferably about 50 to 90 ° C, and still more preferably about 60 to 80 ° C. The preheating time is preferably about 30 seconds to 15 minutes, more preferably about 1 to 10 minutes, and further preferably about 2 to 5 minutes. Moreover, the said air blow can be normally performed by spraying the air heated to the normal temperature or the temperature of about 25 to 80 degreeC on the coating surface of the to-be-coated article for about 30 seconds to 15 minutes.

  When the water-based coating composition of the present invention forms a multilayer coating film comprising a base coat film and a clear coat film on an article to be coated such as an automobile body by a 2-coat 1-bake method, It can be used suitably. The coating film formation method in this case can be performed according to the following method I.

Method I
(1) A step of forming a base coat film by applying the aqueous coating composition of the present invention to an object to be coated;
(2) a step of applying a clear coat coating composition on the uncured base coat film to form a clear coat film; and (3) the uncured base coat film and the uncured clear coat film. A method for forming a multilayer coating film comprising a step of heating the coating film to simultaneously cure both coating films.

  The object to be coated in Method I is preferably an automobile body with an undercoat film, an automobile body with an undercoat film and an intermediate coat film, and the like. The undercoat coating film is preferably a coating film formed of an electrodeposition coating, and more preferably a coating formed of a cationic electrodeposition coating.

  In the present invention, the cured coating film is a cured and dried state specified in JIS K 5600-1-1 (2004), that is, the center of the coating surface is strongly sandwiched between the thumb and the index finger, and the coating surface is dented by a fingerprint. It is a coating film in which the movement of the coating film is not felt, the center of the coating surface is rapidly rubbed with a fingertip, and the coating surface is not rubbed. On the other hand, an uncured coating film is a state in which the coating film has not reached the above-mentioned cured and dried state, and includes a dry-to-touch state and a semi-cured and dried state defined in JIS K 5600-1-1.

  When the aqueous coating composition of the present invention is applied by the 2-coat 1-bake method of the above method I, the coating film thickness is preferably about 3 to 40 μm, more preferably about 5 to 30 μm, and more preferably 8 It is more preferably about ˜25 μm, and particularly preferably about 10 to 18 μm. The coating thickness of the clear coat coating composition is preferably about 10 to 80 μm, more preferably about 15 to 60 μm, and still more preferably about 20 to 45 μm as the cured film thickness.

  Further, in the method I, after the application of the aqueous coating composition, from the viewpoint of preventing the occurrence of coating film defects such as armpits, the above-mentioned preheating, air blowing, etc. are performed under heating conditions in which the coating film is not substantially cured. Is preferred. In addition, after the application of the clear coat coating composition, an interval of about 1 to 60 minutes can be provided at room temperature, or preheating can be performed at about 40 to 80 ° C. for about 1 to 60 minutes, if necessary.

  Curing of the water-based coating composition and the clear coat coating composition can be performed by the known heating means described above. The heating temperature is preferably about 80 to 180 ° C, more preferably about 100 to 170 ° C, and still more preferably about 120 to 160 ° C. The heating time is preferably about 10 to 60 minutes, and more preferably about 20 to 40 minutes. By this heating, both the base coat and the clear coat can be cured simultaneously.

  The water-based coating composition of the present invention is a three-coat one-bake method in which a multilayer coating film composed of a first colored coating film, a second colored coating film, and a clear coating film is applied to an object such as an automobile body. In the case of forming, it can be suitably used for forming the second colored coating film. The coating film formation method in this case can be performed according to the following method II.

Method II
(1) A step of forming a first colored coating film by applying a first colored coating composition to an object to be coated;
(2) A step of forming the second colored coating film by coating the aqueous coating composition of the present invention on the uncured first colored coating film,
(3) a step of applying a clear coat coating composition on the uncured second colored coating film to form a clear coat coating; and (4) the uncured first colored coating film, uncured A method for forming a multilayer coating film comprising a step of simultaneously heating and curing a second colored coating film and an uncured clear coat film.

  In the method II, the coating method of the method I is performed on an uncured first colored coating film. As the article to be coated in Method II, an automobile body or the like on which an undercoat film is formed is preferable. The undercoat coating film is preferably formed of an electrodeposition paint, and more preferably formed of a cationic electrodeposition paint.

  In the method II, the coating thickness of the first colored coating composition is usually preferably about 3 to 50 μm, more preferably about 5 to 30 μm, and still more preferably about 10 to 25 μm as a cured film thickness. In addition, the coating film thickness of the aqueous coating composition of the present invention is preferably about 1 to 30 μm, more preferably about 3 to 25 μm, and still more preferably about 5 to 20 μm as the cured film thickness. Further, the coating film thickness of the clear coat coating composition is usually preferably about 10 to 80 μm, more preferably about 15 to 60 μm, and still more preferably about 20 to 45 μm as a cured film thickness.

  Specific examples of the method II include the following method II-1 and method II-2.

Method II-1
(1) A step of applying a surface treatment to the steel sheet as necessary, coating an electrodeposition paint thereon, and curing it by heating to form a cured electrodeposition coating film;
(2) In the intermediate coating booth, a step of coating the first colored coating composition on the cured electrodeposition coating film obtained in step (1) to form an intermediate coating film;
(3) In the base coat painting booth, a step of coating the aqueous coating composition of the present invention on the uncured intermediate coating film obtained in step (2) to form a base coat;
(4) In the clear coat coating booth, a step of applying a clear coat paint on the base coat coated surface obtained in step (3) to form a clear coat film, and (5) steps (2) to (4) A method for forming a multilayer coating film comprising the step of simultaneously curing the three coating films by heating the intermediate coating film, base coat and clear coat formed in (1).

  The booth is a facility for maintaining the coating environment such as temperature and humidity within a certain range in order to ensure uniform coating quality, and is usually divided according to the type of paint to be painted. In the same booth, the same paint may be applied twice in order to prevent sagging or unevenness of the paint applied to the object. In this case, the first painting is called the first stage painting, and the second painting is called the second stage painting.

  In Method II-1, the coating thickness of the first colored coating composition is usually preferably about 5 to 50 μm, more preferably about 10 to 30 μm, and still more preferably about 15 to 25 μm in terms of cured film thickness. In addition, the coating film thickness of the aqueous coating composition of the present invention is preferably about 3 to 30 μm, more preferably about 5 to 25 μm, further preferably about 8 to 20 μm, and more preferably about 9 to 16 μm as the cured film thickness. preferable. Further, the coating film thickness of the clear coat coating composition is usually preferably about 10 to 80 μm, more preferably about 15 to 60 μm, and still more preferably about 20 to 45 μm in terms of cured film thickness.

  Moreover, in the said method II-1, when the aqueous | water-based 1st colored coating composition is used as a 1st colored coating composition, after application | coating of this aqueous | water-based 1st colored coating composition, generation | occurrence | production of coating-film defects, such as an armpit. From the viewpoint of prevention, it is preferable to perform the above-described preheating, air blowing, or the like under heating conditions in which the coating film is not substantially cured.

Method II-2
(1) A step of applying a surface treatment to the steel sheet as necessary, coating an electrodeposition paint thereon, and curing it by heating to form a cured electrodeposition coating film;
(2) In the first stage of the base coat painting booth, a step of coating the first base coat paint on the cured electrodeposition paint film obtained in step (1) to form the first base coat paint film;
(3) In the second stage of the base coat painting booth, a step of coating the aqueous base coating composition of the present invention on the first base coat film obtained in step (2) to form a second base coat film;
(4) In the clear coat coating booth, a step of applying a clear coat paint on the second base coat film obtained in step (3) to form a clear coat film, and (5) steps (2) to (2) A step of simultaneously curing these three coating films by heating the first base coat film, the second base coat film and the clear coat film formed in (4),
A method for forming a multilayer coating film comprising:

  In the above method II-2, the coating thickness of the first colored coating composition is usually preferably about 3 to 40 μm, more preferably about 5 to 25 μm, and still more preferably about 10 to 20 μm as a cured film thickness. The coating film thickness of the aqueous coating composition of the present invention is preferably about 1 to 25 μm, more preferably about 3 to 20 μm, and still more preferably about 5 to 15 μm as the cured film thickness. Further, the coating film thickness of the clear coat coating composition is usually preferably about 10 to 80 μm, more preferably about 15 to 60 μm, and still more preferably about 20 to 45 μm in terms of cured film thickness.

  The coating method of Method II-2 does not require an intermediate coating booth, and thus has an advantage that energy for adjusting the temperature and humidity of the intermediate coating booth can be reduced.

  Further, in the coating method of Method II-2, since the first colored coating composition and the aqueous coating composition of the present invention are applied at the base coat coating booth, the first colored coating composition is usually applied and the present invention is applied. The heating device is not installed during the application of the aqueous coating composition, and the above-mentioned preheating is generally not performed on the first base coat film formed by applying the first colored coating composition. For this reason, this method II-2 has the advantage that the energy for preheating can be reduced. Therefore, from the viewpoint of energy saving, in the coating method of the above method II-2, it is preferable not to include a heating step between the coating of the first colored coating composition and the coating of the aqueous coating composition of the present invention.

  Further, in the method II, after the application of the aqueous coating composition of the present invention, from the viewpoint of preventing the occurrence of coating film defects such as armpits, the above-mentioned preheating, air blowing, etc. are performed under heating conditions in which the coating film is not substantially cured. Preferably it is done. In addition, after the application of the clear coat coating composition, an interval of about 1 to 60 minutes can be provided at room temperature, or preheating can be performed at about 40 to 80 ° C. for about 1 to 60 minutes, if necessary.

  Heat curing of the three-layer coating film of the uncured first colored coating film, the uncured second colored coating film, and the uncured clear coat film can be performed by the known heating means described above. The heating temperature is preferably about 80 to 180 ° C, more preferably about 100 to 170 ° C, and still more preferably about 120 to 160 ° C. The heating time is preferably about 10 to 60 minutes, and more preferably about 20 to 40 minutes. By this heating, the three-layer coating film of the first colored coating film, the second colored coating film, and the clear coat coating film can be simultaneously cured.

  As the clear coat coating composition used in the above methods I and II, any known thermosetting clear coat coating composition for coating automobile bodies can be used. Examples thereof include an organic solvent-type thermosetting coating composition, a water-based thermosetting coating composition, and a powder thermosetting coating composition containing a base resin having a crosslinkable functional group and a crosslinking agent.

  Examples of the crosslinkable functional group possessed by the base resin include a carboxyl group, a hydroxyl group, an epoxy group, and a silanol group. Examples of the base resin include acrylic resin, polyester resin, alkyd resin, urethane resin, epoxy resin, and fluorine resin. Examples of the crosslinking agent include polyisocyanate compounds, blocked polyisocyanate compounds, melamine resins, urea resins, carboxyl group-containing compounds, carboxyl group-containing resins, epoxy group-containing resins, and epoxy group-containing compounds.

  The base resin / crosslinking agent combination of the clear coat coating composition includes carboxyl group-containing resin / epoxy group-containing resin, hydroxyl group-containing resin / polyisocyanate compound, hydroxyl group-containing resin / blocked polyisocyanate compound, hydroxyl group-containing resin / melamine resin. Etc. are preferred.

  In addition, the clear coat coating composition may be a one-component paint or a multi-component paint such as a two-component urethane resin paint.

  In addition, the clear coat coating composition may contain, if necessary, a coloring pigment, a bright pigment, a dye, and the like to such an extent that transparency is not hindered, and further an extender pigment, an ultraviolet absorber, and a light stabilizer. An antifoaming agent, a thickener, a rust inhibitor, a surface conditioner, and the like can be appropriately contained.

  As the first colored coating composition used in the method II, for example, a known thermosetting intermediate coating composition can be used in the method II-1, and a known coating composition in the method II-2. A thermosetting basecoat coating composition can be used. Specifically, for example, a thermosetting coating composition containing a base resin having a crosslinkable functional group, a crosslinker, a color pigment, and an extender pigment can be suitably used.

Examples of the crosslinkable functional group possessed by the base resin include a carboxyl group, a hydroxyl group, and an epoxy group. Examples of the base resin include acrylic resin, polyester resin, alkyd resin, and urethane resin. Examples of the crosslinking agent include melamine resin, polyisocyanate compound, blocked polyisocyanate compound and the like.
As the first colored coating composition, any of an organic solvent-type coating composition, an aqueous coating composition, and a powder coating composition may be used. Of these, it is preferable to use an aqueous coating composition.

  In the above methods I and II, the first colored coating composition and the clear coat coating composition can be applied by a known method such as air spray coating, airless spray coating, or rotary atomization coating. .

  Hereinafter, the present invention will be described more specifically with reference to production examples, examples and comparative examples. However, the present invention is not limited to these. In each example, “parts” and “%” are based on mass unless otherwise specified. Moreover, the film thickness of a coating film is based on a cured coating film.

Production and production example 1 of polymerizable unsaturated monomer (a1) having urea bond
A reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser and dropping device was charged with 40 parts of tetrahydrofuran and 52.9 parts of 2-methacryloyloxyethyl isocyanate, and the temperature was lowered to 15 ° C. Next, 37 parts of a 37.8% methanol solution of ethylamine was added dropwise over 1 hour while stirring at 15 ° C., and after completion of the addition, the mixture was aged by stirring at room temperature for 2 hours. Next, the temperature is raised to 60 ° C., and the solvent is removed under reduced pressure to thereby remove the polymerizable unsaturated monomer (a1-1) having a urea bond (2- (3-ethylureido) ethyl methacrylate, active ingredient 100%). Got. The polymerizable unsaturated monomer (a1-1) having a urea bond has an ethylurea group.

Production Example 2
A reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser and dropping device was charged with 40 parts of tetrahydrofuran and 51.2 parts of 2-methacryloyloxyethyl isocyanate, and the temperature was raised to 35 ° C. Next, 24.1 parts of butylamine was added dropwise over 1 hour with stirring while maintaining 35 ° C. After completion of the dropwise addition, the mixture was aged by stirring at 35 ° C for 2 hours. Next, the temperature is raised to 60 ° C., and the solvent is removed under reduced pressure to thereby remove a polymerizable unsaturated monomer having a urea bond (a1-2) (2- (3-butylureido) ethyl methacrylate, active ingredient 100%). Got. In addition, the polymerizable unsaturated monomer (a1-2) having a urea bond has a butylurea group.

Production Example 3
A reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser and dropping device was charged with 40 parts of tetrahydrofuran and 51.2 parts of 2-methacryloyloxyethyl isocyanate, and the temperature was raised to 35 ° C. Next, 19.5 parts of isopropylamine was added dropwise over 1 hour with stirring while maintaining 35 ° C. After completion of the dropwise addition, the mixture was aged by stirring at 35 ° C for 2 hours. Next, the temperature is raised to 60 ° C., and the solvent is removed under reduced pressure to thereby remove a polymerizable unsaturated monomer having a urea bond (a1-3) (2- (3-isopropylureido) ethyl methacrylate, active ingredient 100%). Got. The polymerizable unsaturated monomer (a1-3) having a urea bond has an isopropyl urea group.

Production Example 4
A reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser and dropping device was charged with 40 parts of tetrahydrofuran and 51.2 parts of 2-methacryloyloxyethyl isocyanate, and the temperature was raised to 35 ° C. Next, while maintaining at 35 ° C., 42.6 parts of 2-ethylhexylamine was added dropwise over 1 hour while stirring, and after completion of the dropwise addition, the mixture was aged by stirring at 35 ° C. for 2 hours. Next, the temperature is raised to 60 ° C., and the solvent is removed under reduced pressure, whereby a polymerizable unsaturated monomer having a urea bond (a1-4) (2- [3- (2-ethylhexyl) ureido] ethyl methacrylate, effective 100% component) was obtained. In addition, the polymerizable unsaturated monomer (a1-4) having a urea bond has a 2-ethylhexyl urea group.

Production Example 5
A reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser and dropping device was charged with 40 parts of tetrahydrofuran and 51.2 parts of 2-methacryloyloxyethyl isocyanate, and the temperature was raised to 35 ° C. Next, 24.1 parts of diethylamine was added dropwise over 1 hour with stirring while maintaining 35 ° C. After completion of the dropwise addition, the mixture was aged by stirring at 35 ° C for 2 hours. Next, the temperature is raised to 60 ° C., and the solvent is removed under reduced pressure, whereby a polymerizable unsaturated monomer having a urea bond (a1-5) (2- (3,3-diethylureido) ethyl methacrylate, active ingredient 100 %). In addition, the polymerizable unsaturated monomer (a1-5) having a urea bond has a diethylurea group.

Production Example 6
A reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, air inlet tube, drying tube and dropping device was charged with 42.9 parts of 2-hydroxyethyl methacrylate and 0.039 parts of p-methoxyphenol and dried. The temperature was raised to 60 ° C. while introducing air at 20 mL per minute. Next, while maintaining 60 ° C., 66.6 parts of isophorone diisocyanate was added dropwise over 1 hour while stirring and introducing dry air. After completion of the dropwise addition, the mixture was aged by stirring at 60 ° C. for 2 hours. . Next, the temperature was raised to 80 ° C., and the mixture was further aged at the same temperature for 1 hour for aging. Next, the temperature was lowered to 10 ° C., 50 parts of tetrahydrofuran was added, and 19.7 parts of butylamine was added dropwise over 1 hour with stirring while maintaining 10 ° C. After completion of dropping, the mixture was aged by stirring at room temperature for 2 hours. Thereafter, the temperature is raised to 60 ° C., and the solvent is removed under reduced pressure, whereby a polymerizable unsaturated monomer having a urea bond (a1-6) (2-{[5- (3-butylureido) -1,3 , 3-Trimethylcyclohexyl] methylcarbamoyloxy} ethyl methacrylate and 2- {3-[(3-butylureido) methyl] -3,5,5-trimethylcyclohexylmethylcarbamoyloxy} ethyl methacrylate, 100% active ingredient ) The polymerizable unsaturated monomer (a1-6) having a urea bond has a butylurea group and a urethane bond.

Production and production example 7 of polymerizable unsaturated monomer (a2) having urethane bond
Into a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, air inlet tube, drying tube and dropping device, 67.7 parts of 2-methacryloyloxyethyl isocyanate and 0.40 part of p-methoxyphenol were charged, The temperature was raised to 50 ° C. while introducing dry air at 20 mL / min. Next, 32.3 parts of butanol was added dropwise over 1 hour while stirring and introducing dry air while maintaining 50 ° C. After completion of the dropping, the temperature was raised to 60 ° C., and the mixture was aged by stirring at the same temperature for 1 hour. Next, the temperature is raised to 100 ° C. and the mixture is aged by stirring at the same temperature for 1 hour, and a polymerizable unsaturated monomer having a urethane bond (a2-1) (2- (butoxycarbonylamino) ethyl methacrylate, active ingredient 100% ) In addition, the polymerizable unsaturated monomer (a2-1) having a urethane bond has a butylurethane group.

Production and production example 8 of polymerizable unsaturated monomer (a3) having an imide bond
In a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, air introduction tube, drying tube and dropping device, 52.4 parts of methacrylic acid, 47.6 parts of N-hydroxyethylphthalimide, 64.2 parts of toluene Then, 0.08 part of p-methoxyphenol and 4.7 parts of p-toluenesulfonic acid monohydrate were charged, and the temperature was raised to 130 ° C. while introducing dry air. Next, the mixture was allowed to undergo a condensation reaction for 3 hours with stirring, and then cooled to 80 ° C., and further 150 parts of toluene was added and cooled to room temperature. Next, 5% by weight aqueous sodium hydroxide solution was added for washing, followed by washing with pure water until neutrality, followed by dehydration with saturated saline. 50 parts of acetone and 1% by weight of sodium sulfate were added to the oil phase for dehydration. Thereafter, sodium sulfate was removed by filtration, heated to 70 ° C., and the solvent was distilled off under reduced pressure until the solid content became 35%. The mixture was cooled to 10 ° C. using ice water, and the precipitated crystals were filtered to obtain a polymerizable unsaturated monomer (a3-1) (1,3-dioxoisoindoline-2-ylethyl methacrylate) having an imide bond. .

Production Example 9 for Macromonomer (m-1)
In a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, nitrogen gas introduction tube and dropping device, 16 parts of ethylene glycol monobutyl ether and 2,4-diphenyl-4-methyl-1-pentene (hereinafter referred to as “ MSD ”(sometimes abbreviated as“ MSD ”) was charged in 3.5 parts, nitrogen gas was passed through the gas phase, and the temperature was raised to 160 ° C. with stirring. When the temperature reached 160 ° C., 30 parts of the polymerizable unsaturated monomer (a1-1) having a urea bond obtained in Production Example 1, 30 parts of 2-hydroxyethyl methacrylate, 40 parts of n-butyl methacrylate and di-tert-amylper A mixed solution consisting of 7 parts of oxide was added dropwise over 3 hours and stirred at the same temperature for 2 hours. Subsequently, it was cooled to 30 ° C. and diluted with ethylene glycol monobutyl ether to obtain a macromonomer solution (m-1-1) having a solid content of 65%. The resulting macromonomer had a hydroxyl value of 125 mg KOH / g and a number average molecular weight of 2,200. Moreover, according to the analysis by proton NMR, 97% or more of the ethylenically unsaturated groups derived from MSD were present at the end of the polymer chain, and 2% had disappeared.
In the above proton NMR analysis, deuterated chloroform was used as a solvent, the peaks (4.8 ppm, 5.1 ppm) based on the protons of the unsaturated group of MSD before and after the polymerization reaction, the ethylenic properties of the macromonomer chain ends. After measuring the peak of the unsaturated group proton (5.0 ppm, 5.2 ppm) and the peak of the aromatic proton derived from MSD (7.2 ppm), the aromatic proton derived from the MSD (7.2 ppm) Was assumed to be unchanged before and after the polymerization reaction, and based on this, each unsaturated group (unreacted, macromonomer chain end, disappearance) was quantified.

Production Examples 10 to 33
The synthesis was performed in the same manner as in Production Example 9 except that the composition shown in Table 1 below was obtained, to obtain macromonomer solutions (m-1-2) to (m-1-25) having a solid content of 65%.

  In Table 1, the raw material composition (parts) of the macromonomer solutions (m-1-1) to (m-1-25), the polymerizable unsaturated monomers (a) and (b) in the monomer component (I) The ratio, hydroxyl value (mgKOH / g) and number average molecular weight are shown.

Production Example 1 of Copolymer
15.4 parts of the macromonomer solution (m-1-1) obtained in Production Example 9 was added to a reaction vessel equipped with a thermometer, a thermostat, a stirrer, a reflux condenser, a nitrogen gas inlet tube and two dropping devices (solid) 10 parts), 20 parts of ethylene glycol monobutyl ether and 30 parts of diethylene glycol monoethyl ether acetate were added, and the temperature was raised to 85 ° C. while blowing nitrogen gas into the liquid. Then, in a reaction vessel maintained at the same temperature, 31.5 parts of N, N-dimethylacrylamide, 31.5 parts of N-isopropylacrylamide, 27 parts of 2-hydroxyethyl acrylate, 10 parts of ethylene glycol monobutyl ether and diethylene glycol monoethyl A mixed solution comprising 40 parts of ether acetate, 0.15 part of “Perbutyl O” (trade name, manufactured by NOF Corporation, polymerization initiator, tert-butylperoxy-2-ethylhexanoate), and ethylene glycol monobutyl ether 20 The mixed solution consisting of parts was dropped into the reaction vessel simultaneously over 4 hours, and after completion of the dropping, the mixture was aged by stirring for 2 hours at the same temperature. Then, in a reaction vessel maintained at the same temperature, a mixed solution consisting of 0.3 part of 2,2′-azobis (2,4-dimethylvaleronitrile) and 15 parts of ethylene glycol monobutyl ether was dropped over 1 hour, After completion of the dropping, the mixture was aged by stirring for 1 hour at the same temperature. Subsequently, it cooled to 30 degreeC, adding ethylene glycol monobutyl ether, and obtained the copolymer solution of 35% of solid content. The weight average molecular weight of the obtained copolymer was 310,000. To the resulting copolymer solution, 215 parts of deionized water was added to obtain a copolymer dilution (RC-1) having a solid content of 20%.

Examples 2-33, Comparative Examples 1-4
The synthesis was performed in the same manner as in Example 1 except that the formulation shown in Table 2 below was obtained, and copolymer dilutions (RC-2) to (RC-37) having a solid content of 20% were obtained.

  Table 2 below shows the raw material compositions (parts) and weight average molecular weights of the copolymer solutions (RC-1) to (RC-37).

(Note 1) “NK-ester AM-90G”: trade name, manufactured by Shin-Nakamura Chemical Co., Ltd., polymerizable unsaturated monomer having a polyoxyalkylene chain, the following general formula (1)

, R ¹ is a hydrogen atom, R ² is a methyl group, R ³ is an ethylene group, m is 9, and the molecular weight is 454.

Production and production example 34 of hydroxyl group-containing acrylic resin (A1)
A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen gas inlet tube and dropping device, 128 parts of deionized water, “ADEKA rear soap SR-1025” (trade name, manufactured by ADEKA, emulsifier, active ingredient) 25%) 3 parts were charged, stirred and mixed in a nitrogen stream, and heated to 80 ° C.

  Next, 1% of the total amount of the following monomer emulsion for core part and 5.3 parts of a 6% aqueous ammonium persulfate solution were introduced into the reaction vessel and maintained at 80 ° C. for 15 minutes. Then, the remainder of the monomer emulsion for core part was dropped into a reaction vessel maintained at the same temperature over 3 hours, and aging was performed for 1 hour after the completion of the dropping. Next, the following monomer emulsion for shell part was added dropwise over 1 hour, and after aging for 1 hour, it was cooled to 30 ° C. while gradually adding 40 parts of 5% 2- (dimethylamino) ethanol aqueous solution to the reaction vessel, A water-dispersible hydroxyl group-containing acrylic resin aqueous dispersion (A1-1) having an average particle size of 95 nm and a solid content of 30% was obtained. The obtained water-dispersible hydroxyl group-containing acrylic resin had an acid value of 33 mgKOH / g and a hydroxyl value of 22 mgKOH / g.

  Monomer emulsion for core part: 40 parts of deionized water, 2.8 parts of “ADEKA rear soap SR-1025”, 2.1 parts of methylenebisacrylamide, 2.8 parts of styrene, 21 parts of n-butyl acrylate, 16 parts of methyl methacrylate .1 part and 28 parts of ethyl acrylate were mixed and stirred to obtain a monomer emulsion for the core part.

  Monomer emulsion for shell part: 17 parts of deionized water, 1.2 parts of “ADEKA rear soap SR-1025”, 0.03 part of ammonium persulfate, 3 parts of styrene, 9 parts of n-butyl acrylate, 2-hydroxyethyl methacrylate 5 .1 part, 5.1 parts of methacrylic acid, 6 parts of methyl methacrylate and 1.8 parts of ethyl acrylate were mixed and stirred to obtain a monomer emulsion for shell part.

Production Examples 35-38
It synthesize | combined similarly to manufacture example 34 except setting it as the mixing | blending shown in the following Table 3, and obtained the water-dispersible hydroxyl-containing acrylic resin water dispersion (A1-2)-(A1-5).

  Table 3 shows the raw material composition (parts), solid content (%), acid value (mgKOH / g), and hydroxyl value of water-dispersible hydroxyl group-containing acrylic resin aqueous dispersions (A1-1) to (A1-5) ( mgKOH / g).

  In Table 3, (A1-1) to (A1-3) and (A1-5) of the water-dispersible hydroxyl group-containing acrylic resin aqueous dispersions (A1-1) to (A1-5) are: It corresponds to the core-shell type water-dispersible hydroxyl group-containing acrylic resin (A1′-1), and (A1-1) to (A1-3) are core-shell type water-dispersible hydroxyl group-containing acrylic resins (A1′-2). )

Production Example 39
A reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen gas 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, 29 parts of n-butyl acrylate, 15 parts of 2-hydroxyethyl acrylate, 6 parts of acrylic acid, 15 parts of propylene glycol monopropyl ether and 2.3 parts of 2,2′-azobis (2,4-dimethylvaleronitrile) 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 (A1-6) 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 40 of Hydroxyl-Containing Polyester Resin (A2) 40
In a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen gas inlet tube and water separator, 109 parts of trimethylolpropane, 141 parts of 1,6-hexanediol, 1,2-cyclohexanedicarboxylic anhydride 126 parts of the product and 120 parts of adipic acid were added, the temperature was raised from 160 ° C. to 230 ° C. over 3 hours, and then a condensation reaction was performed at 230 ° C. for 4 hours. Subsequently, in order to introduce a carboxyl group into the obtained condensation reaction product, 38.3 parts of trimellitic anhydride was added and reacted at 170 ° C. for 30 minutes, and then 2-ethyl-1-hexanol (20 Dilution was carried out at 100 ° C. with a mass dissolved in 100 g of water (0.1 g) to obtain a hydroxyl group-containing polyester resin solution (A2-1) having a solid content of 70%. The obtained hydroxyl group-containing polyester resin had an acid value of 46 mgKOH / g, a hydroxyl value of 150 mgKOH / g, and a number average molecular weight of 1,400. In the raw material composition, the total content of the alicyclic polybasic acid in the acid component was 46 mol% based on the total amount of the acid component.

Production Example 41
In a reaction vessel equipped with a thermometer, thermostat, stirring device, reflux condenser, nitrogen gas inlet tube and water separator, 113 parts of trimethylolpropane, 131 parts of neopentyl glycol, 80 parts of 1,2-cyclohexanedicarboxylic anhydride Then, 93 parts of isophthalic acid and 91 parts of adipic acid were charged, and the temperature was raised from 160 ° C. to 230 ° C. over 3 hours, followed by a condensation reaction at 230 ° C. for 4 hours. Next, in order to introduce a carboxyl group into the resulting condensation reaction product, 33.5 parts of trimellitic anhydride was further added, reacted at 170 ° C. for 30 minutes, and then diluted with 2-ethyl-1-hexanol. A hydroxyl group-containing polyester resin solution (A2-2) having a solid content of 70% was obtained. The obtained hydroxyl group-containing polyester resin had an acid value of 40 mgKOH / g, a hydroxyl value of 161 mgKOH / g, and a number average molecular weight of 1,300. In the raw material composition, the total content of the alicyclic polybasic acid in the acid component was 28 mol% based on the total amount of the acid component.

Production Example 42
A hydroxyl group-containing polyester resin solution (A2) was prepared in the same manner as in Production Example 40 except that 2-ethyl-1-hexanol as a dilution solvent was changed to ethylene glycol monobutyl ether (mass dissolved in 100 g of water at 20 ° C .: infinite). -3) was obtained.

Production and production example 43 of aluminum pigment dispersion
In a stirring and mixing container, “GX-180A” (trade name, manufactured by Asahi Kasei Metals, aluminum pigment paste, aluminum content 74%) 19 parts (solid content 14 parts), 2-ethyl-1-hexanol 35 parts, 8 parts of phosphoric acid group-containing resin solution (4 parts of solid content) and 0.2 part of 2- (dimethylamino) ethanol were mixed uniformly to obtain an aluminum pigment dispersion (P-1).
Phosphate group-containing resin solution: put a mixed solvent of 27.5 parts of methoxypropanol and 27.5 parts of isobutanol into a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen gas inlet tube and dropping device. , Heated to 110 ° C., 25 parts of styrene, 27.5 parts of n-butyl methacrylate, 20 parts of “isostearyl acrylate” (trade name, Osaka Organic Chemical Industries, Ltd., branched higher alkyl acrylate), 4-hydroxybutyl acrylate 7 121.5 parts of a mixture comprising 5 parts, 15 parts of the following phosphoric acid group-containing polymerizable monomer, 12.5 parts of 2-methacryloyloxyethyl acid phosphate, 10 parts of isobutanol, and 4 parts of t-butylperoxyoctanoate In addition to the above mixed solvent over 4 hours, 0.5 parts of t-butylperoxyoctanoate A mixture of isopropanol 20 parts was added dropwise for 1 hour. Thereafter, the mixture was aged and stirred for 1 hour to obtain a phosphate group-containing resin solution having a solid concentration of 50%. The acid value due to the phosphoric acid group of this resin was 83 mgKOH / g, the hydroxyl value was 29 mgKOH / g, and the weight average molecular weight was 10,000.
Phosphoric acid group-containing polymerizable monomer: put 57.5 parts of monobutyl phosphoric acid and 41 parts of isobutanol in a reaction vessel equipped with a thermometer, thermostat, stirrer, reflux condenser, nitrogen gas introduction tube and dropping device, and bring it to 90 ° C. After raising the temperature, 42.5 parts of glycidyl methacrylate was added dropwise over 2 hours, followed by stirring and aging for another hour. Thereafter, 59 parts of isopropanol was added to obtain a phosphate group-containing polymerizable monomer solution having a solid content concentration of 50%. The acid value of the obtained monomer was 285 mgKOH / g.

Production Example 44
An aluminum pigment dispersion (P-2) was obtained in the same manner as in Production Example 43, except that 35 parts of 2-ethyl-1-hexanol was changed to 35 parts of ethylene glycol monobutyl ether.

Production Example 34 of water-based coating composition
In a stirring and mixing container, 100 parts of water-dispersible hydroxyl group-containing acrylic resin aqueous dispersion (A1-1) obtained in Production Example 34 (solid content 30 parts), and a hydroxyl group-containing acrylic resin solution obtained in Production Example 39 (A1-6) ) 18 parts (solid content 10 parts), 43 parts of the hydroxyl group-containing polyester resin solution (A2-1) obtained in Production Example 40 (solid content 30 parts), and the aluminum pigment dispersion (P-1) obtained in Production Example 43 62 parts and 50 parts of melamine resin (B-1) (methyl-butyl mixed etherified melamine resin, solid content 60%, weight average molecular weight 2,000) (solid content 30 parts) are mixed uniformly, A water-based paint having a pH of 8.0 and a solid content of 25% by adding 5 parts of the copolymer diluent (RC-1) obtained in Example 1 (1 part of solid content), 2- (dimethylamino) ethanol and deionized water. A composition (X-1) was obtained.

Examples 35-75 and Comparative Examples 5-10
Aqueous coating compositions (X-2) to (X-48) having a pH of 8.0 and a solid content of 25% were obtained in the same manner as in Example 34 except that the blending composition was as shown in Table 4 below. .

(Note 2) Melamine resin (B-2): methyl etherified melamine resin, solid content 80%, weight average molecular weight 800.
(Note 3) “Baihijole VPLS2310”: trade name, manufactured by Sumika Bayer Urethane Co., Ltd., blocked polyisocyanate compound, solid content 38%.
(Note 4) “ACRYSOL RM-825”: trade name, manufactured by Rohm and Haas, urethane associative viscosity modifier, solid content 25%.

Example 45 of manufacturing article to be coated
A thermosetting epoxy resin-based cationic electrodeposition coating composition (trade name “Electron GT-10”, manufactured by Kansai Paint Co., Ltd.) is applied to a 30 cm × 45 cm zinc phosphate-treated cold rolled steel sheet so as to have a film thickness of 20 μm. It was electrodeposited and cured by heating at 170 ° C. for 30 minutes. Next, an intermediate coating composition (trade name “TP-65-2”, manufactured by Kansai Paint Co., Ltd., polyester resin / amino resin organic solvent type coating composition) is formed on the electrodeposition coating film to a film thickness of 35 μm. And cured by heating at 140 ° C. for 30 minutes. Thus, an article to be coated formed by forming an electrodeposition coating film and an intermediate coating film on a steel plate was produced.

Coating film forming method Example 76
Using the aqueous coating composition (X-1) obtained in Example 34 as a base coat forming coating in the two-coat one-bake method of the above-mentioned coating film forming method I, a base coat and a clear coat are applied onto the article to be coated. A multilayer coating film was formed.
That is, the aqueous coating composition (X-1) was applied to the article obtained in Production Example 45 so as to have a film thickness of 15 μm using a rotary atomizing bell-type coating machine and left for 2 minutes. Thereafter, preheating was performed at 80 ° C. for 3 minutes. Next, an acrylic resin-based organic solvent-type clear coating composition (trade name “Magicron KINO-1210”, manufactured by Kansai Paint Co., Ltd.) was applied to the uncured coating surface so as to have a film thickness of 40 μm and left for 7 minutes. Thereafter, both coatings were cured simultaneously by heating at 140 ° C. for 30 minutes. Thus, a test plate was obtained in which a multilayer coating film composed of a base coat and a clear coat was formed on an object to be coated.

Examples 77-117 and Comparative Examples 11-16
Test plates of Examples 77 to 117 and Comparative Examples 11 to 16 in the same manner as in Example 76 except that the aqueous coating composition shown in Table 5 was used instead of the aqueous coating composition (X-1). Got.

Example 118
A thermosetting epoxy resin-based cationic electrodeposition coating composition (trade name “Electron GT-10”, manufactured by Kansai Paint Co., Ltd.) is applied to a 30 cm × 45 cm zinc phosphate-treated cold rolled steel sheet so as to have a film thickness of 20 μm. It was electrodeposited and cured by heating at 170 ° C. for 30 minutes. Next, a first colored coating composition (trade name “TP-65-2”, manufactured by Kansai Paint Co., Ltd., polyester resin / amino resin organic solvent type coating composition) is formed on the electrodeposition coating film to a thickness of 25 μm. After being coated for 5 minutes and then allowed to stand for 5 minutes, preheating was performed at 80 ° C. for 5 minutes. Next, after setting for 7 minutes, the aqueous coating composition (X-1) was applied on the uncured coating surface to a film thickness of 15 μm using a rotary atomizing bell type coating machine for 2 minutes. After standing, preheating was performed at 80 ° C. for 3 minutes. Next, an acrylic resin-based organic solvent-type clear coating composition (trade name “Magicron KINO-1210”, manufactured by Kansai Paint Co., Ltd.) was applied to the uncured coating surface so as to have a film thickness of 40 μm and left for 7 minutes. Thereafter, this three-layer coating film was simultaneously cured by heating at 140 ° C. for 30 minutes.
Thus, the aqueous paint composition (X-1) obtained in Example 34 was used as a base coat-forming paint (second paint composition) in the 3-coat 1-bake method of the paint film-forming method II, and electrodeposition coating was performed. A test plate was obtained in which a multilayer coating film comprising a first colored coating film, a second colored coating film, and a clear coat coating film was formed on the film.

Comparative Example 17
A test plate of Comparative Example 17 was obtained in the same manner as in Example 118 except that the aqueous coating composition (X-43) was used instead of the aqueous coating composition (X-1).

Evaluation Test The test plates obtained in Examples 76 to 118 and Comparative Examples 11 to 17 were evaluated for smoothness, sharpness, flip-flop properties, metallic unevenness, and water resistance. The test method is as follows.

  Smoothness: The smoothness of each test plate was evaluated based on the Long Wave (LW) value measured by “Wave Scan” (trade name, manufactured by BYK Gardner). It shows that the smoothness of a coating surface is so high that LW value is small.

  Sharpness: The sharpness of each test plate was evaluated based on the Short Wave (SW) value measured by “Wave Scan” (trade name, manufactured by BYK Gardner). The smaller the SW value, the higher the clearness of the paint surface.

Flip-flop property: Each test plate was visually observed at different angles, and the flip-flop property was evaluated according to the following criteria.
(Double-circle): The change of the brightness by a visual angle is remarkable (it has extremely excellent flip-flop property).
◯: The change in brightness depending on the viewing angle is large (excellent flip-flop property).
(Triangle | delta): The change of the brightness by a visual angle is a little small (flip-flop property is a little inferior).
X: The change of the brightness by a visual angle is small (flip-flop property is inferior).

Metallic unevenness: Each test plate was visually observed, and the degree of occurrence of metallic unevenness was evaluated according to the following criteria.
A: Almost no metallic unevenness is observed, and the coating film has an excellent appearance.
○: Metallic unevenness is slightly observed, but has excellent coating appearance.
(Triangle | delta): Metallic nonuniformity is recognized and a coating-film external appearance is inferior somewhat.
X: Many metallic irregularities are recognized and the coating film appearance is inferior.

Water resistance: After immersing the test plate in warm water at 40 ° C. for 240 hours, pulling it up and drying at 20 ° C. for 12 hours, cut the multilayer coating film on the test plate into a lattice shape with a cutter so as to reach the substrate, Make 100 2mm x 2mm gobangs. Then, the adhesive cellophane tape was stuck on the surface, and the remaining state of the goby eye coating after the tape was rapidly peeled off at 20 ° C. was examined. The evaluation criteria for water resistance are as follows.
(Double-circle): 100 gobang eyes coating film remains, and no flick is produced,
◯: 100 gobanged paint films remain, but there are spots
(Triangle | delta): 90-99 pieces of Goban eyes coating films remain,
X: The remaining number of gobang eye coats is 89 or less.

Comprehensive evaluation: In the field of painting on an object such as an automobile to which the present invention belongs, it is very important that all the smoothness, sharpness, glitter and water resistance of the coating film are excellent. . Therefore, a comprehensive evaluation was performed based on the following criteria:
A: Smoothness is 9 or less, sharpness is 11 or less, and flip-flop property, metallic unevenness and water resistance are all A.
○: Smoothness is 9 or less, sharpness is 11 or less, flip-flop property, metallic unevenness and water resistance are all ◎ or ○, and at least one of these three items is ◯. .
Δ: Smoothness is 9 or less, sharpness is 11 or less, flip-flop property, metallic unevenness and water resistance are all ◎, ○ or Δ, and at least one of these three items is Δ It is.
X: Smoothness is 10 or more, sharpness is 12 or more, or at least one of flip-flop property, metallic unevenness and water resistance is x.

  Table 5 shows the coating performance test results.

Claims (4)

(M-1) (a) From the group consisting of a polymerizable unsaturated monomer (a1) having a urea bond, a polymerizable unsaturated monomer (a2) having a urethane bond, and a polymerizable unsaturated monomer (a3) having an imide bond Polymerize monomer component (I) comprising 5 to 100% by mass of at least one polymerizable unsaturated monomer selected and (b) 0 to 95% by mass of polymerizable unsaturated monomer other than the polymerizable unsaturated monomer (a). A macromonomer having a basic skeleton composed of a polymer having a number average molecular weight within the range of 1,000 to 10,000, and having a polymerizable unsaturated group, and (m-2) a hydrophilic group A viscosity modifier comprising a copolymer obtained by copolymerizing a monomer component (m) containing a polymerizable unsaturated monomer having A polymerizable unsaturated monomer having a hydrophilic group (m-2) is N-substituted (meth) acrylamide, a polymerizable unsaturated monomer having a polyoxyalkylene chain, N-vinyl-2-pyrrolidone, 2-hydroxyethyl acrylate, The viscosity modifier comprising a copolymer according to claim 1, which is at least one polymerizable unsaturated monomer selected from the group consisting of acrylic acid and methacrylic acid. The monomer component (m) is based on the total mass of the monomer component (m), the macromonomer (m-1) 1 to 40% by mass, the polymerizable unsaturated monomer (m-2) 5 to 99 having a hydrophilic group It consists of 0-94 mass% of polymerizable unsaturated monomers (m-3) other than the above-mentioned polymerizable unsaturated monomers (m-1) and (m-2). A viscosity modifier comprising the described copolymer. The monomer component (I) contains, as at least a part thereof, 5 to 60% by mass of a hydroxyl group-containing polymerizable unsaturated monomer based on the total mass of the monomer component (I). A viscosity modifier comprising the copolymer according to Item.