JP5713502B2 - Water-based paint composition - Google Patents

Description

  The present invention is a nitrogen-containing unsaturated compound having at least one hydrogen bond selected from an ethylenically unsaturated monomer having a urethane bond, an ethylenically unsaturated monomer having an imide bond, and an ethylenically unsaturated monomer having a urea bond. A thermosetting acrylic resin composition comprising a monomer (A) as a copolymerization monomer, and a water-based paint comprising a thickener exhibiting a hydrophobic interaction with the thermosetting acrylic resin composition Relates to the composition.

  Water-based paints refer to paints that use water as the main dilution medium (solvent or dispersion medium), and have been widely used in recent years due to less environmental pollution due to volatilization of solvents into the atmosphere compared to solvent-based paints that have been widely used in the past. It has been used.

  However, since water-based paints are slower to volatilize water than organic solvents, the viscosity increases with the increase in the solid concentration of the paint film during painting. There was a weak point that a mixed layer was likely to occur during layering (wet-on-wet). These weak points reduce the appearance quality of the coating film and lead to the loss of the commercial value of the painted object.

  For this reason, various devices have been devised (= rheology control) for adjusting the flow characteristics of the paint (coating liquid), particularly for increasing the viscosity after coating.

The sagging of the coating film and the mixed layer of the wet coating film in question are slow displacements, and at this time, it is preferable that the viscosity is high. On the other hand, applying a paint by spraying or brushing is a fast displacement, and at this time, it is preferable that the viscosity is low due to the atomization of paint at the time of spraying and the rusting at the time of brushing. That is, it is considered preferable that the paint (coating liquid) exhibits such flow characteristics that the viscosity changes according to the speed. Various techniques for realizing favorable flow characteristics have been conventionally known.
The present invention relates to a paint using an acrylic resin as a binder, and a flow characteristic improving technique conventionally known for such a paint system will be described.

  First, an acrylic resin as a binder will be described. Conventionally, acrylic resins have been widely used as one of typical binders for water-based coating compositions. Among them, acrylic resins copolymerized with hydrogen-bonding monomers exhibit a thickening effect due to hydrogen bonding between resin molecules when used in water-based paints, and therefore have a rheology control property (hereinafter referred to as “rhecon properties”). Is preferably used. For example, Patent Document 1 discloses a heat-sensitive gelling emulsion containing a polymer obtained by copolymerizing an ethylenically unsaturated monomer having a urea bond. Here, the ethylenically unsaturated monomer having a urea bond is a hydrogen bonding monomer.

  Patent Document 2 has a description that “a hydrogen bonding monomer is a monomer having a hydrogen bonding functional group, for example, a monomer having a hydroxyl group, a carboxylic acid, an amino group, a sulfonic acid, an amide group”. In addition, Patent Document 3 discloses that “hydrogen bondable functional groups include alcoholic hydroxyl groups, phenolic hydroxyl groups, amino groups, carbonyl groups, carboxyl groups, amide bonds, ester bonds, carbonate bonds, urethanes. There is also a description of `` including a structure such as a bond, an imide bond, an ether bond, etc. '', and there are a wide variety of hydrogen-bonding monomers having a hydrogen-bonding functional group or a structure exhibiting hydrogen bondability, Many acrylic resins obtained by copolymerizing one or more of these have been disclosed so far.

  In particular, an acrylic resin obtained by copolymerizing a monomer exhibiting hydrogen bonding and self-curing property is known. Patent Document 4 discloses such monomers as N-methoxymethyl (meth) acrylamide, N-methoxyethyl (meth) acrylamide, Nn-butoxymethyl (meth) acrylamide, Ni-butoxymethyl (meth) acrylamide, and N-methylol. An aqueous paint using an acrylic resin copolymerized with an acrylamide derivative such as (meth) acrylamide as a binder is disclosed. Since the binder has self-curing properties due to these monomers, an increase in viscosity due to cross-linking during heat curing of the paint occurs, and an effect of suppressing sagging and mixed layers can be obtained.

  However, the acrylamide monomer has problems such as high hydrophilicity and poor water resistance of the coating film, and thermal yellowing when the coating film is heated and cured.

  In this regard, the present inventors have one or more hydrogen bonding properties selected from an ethylenically unsaturated monomer having a urethane bond, an ethylenically unsaturated monomer having an imide bond, and an ethylenically unsaturated monomer having a urea bond. It has been found that the above-mentioned problems can be solved by a thermosetting acrylic resin composition characterized in that it contains a nitrogen-containing unsaturated monomer (A) having the above as a copolymerization monomer. The water-based coating composition using the thermosetting acrylic resin as a binder satisfies both the rheocon properties and the curability.

  However, a nitrogen-containing unsaturated monomer having one or more hydrogen bonds selected from an ethylenically unsaturated monomer having a urethane bond, an ethylenically unsaturated monomer having an imide bond, and an ethylenically unsaturated monomer having a urea bond. It was subsequently found that a novel aqueous coating composition containing a thermosetting acrylic resin containing (A) as a copolymerization monomer may be somewhat lacking in resistance to repellency and dents. This is because the viscosity increase of the coated film is still insufficient, and the local abnormal flow caused by a small amount of low-polarity contaminants mixed in from the environment during painting or setting before baking, i.e. dot-like on the coating surface. It is thought that cissors and dents occur.

  Next, paint additives will be described. Conventionally, various flow control agents (reocon agents) are known as additives for water-based paints. Non-Patent Document 1 introduces various additives for paints, and Chapter 4 introduces a flow regulator that meets the purpose of the present invention as a “thixotropic agent for controlling viscosity”. Of these, polyacrylic acid compounds, polyurethane compounds, polyamide compounds, and urethane-urea compounds all interact with binder resins, especially emulsion particles, when used in water-based paints, exhibiting excellent thickening effects. It is described that it is effective in suppressing the above. However, there is no mention of using a rheocon agent as a means for suppressing surface defects such as repellency and dents in water-based paints.

JP 2005-213396 A JP 2006-167679 A International Publication No. 2008/029777 Pamphlet JP-A-10-316888

“Paint Additives”, Color Material Association, 83, 430-439 (2010)

  An object of the present invention is to provide a water-based coating composition that is resistant to thermal yellowing and is excellent in rheocon properties, finish properties, and repellency.

  As a result of intensive studies, the present inventors have found that at least one selected from ethylenically unsaturated monomers having a urethane bond, ethylenically unsaturated monomers having an imide bond, and ethylenically unsaturated monomers having a urea bond. A thermosetting acrylic resin composition comprising a nitrogen-containing unsaturated monomer (A) having hydrogen bonding properties as a copolymerization monomer, and a thickening agent exhibiting hydrophobic interaction with the thermosetting acrylic resin The present inventors have found that an aqueous coating composition containing an agent can solve the above-mentioned problems, and have completed the present invention.

Thus, the present invention comprises the following items.
1. Nitrogen-containing unsaturated monomer having one or more hydrogen bonds selected from ethylenically unsaturated monomers having urethane bonds, ethylenically unsaturated monomers having imide bonds, and ethylenically unsaturated monomers having urea bonds (A ) And an unsaturated monomer (B) other than the unsaturated monomer (A), and a thickening agent that exhibits hydrophobic interaction with the acrylic resin composition. An aqueous coating composition comprising:
The thermosetting acrylic emulsion composition in which the thermosetting acrylic resin composition is dispersed in water, the thermosetting acrylic emulsion composition has a core-shell structure, and the mass ratio of the core to the shell is 1/9 to 9/1, and the amount of the nitrogen-containing unsaturated monomer (A) having hydrogen bonding in the shell part is 3 to 70% by mass of the total amount of the unsaturated monomers constituting the shell part,
The thickener is a urethane-urea thickener in which at least a part of the main chain is a hydrophobic urethane chain, or an amide-urea thickener in which at least a part of the main chain is a hydrophobic amide chain. A water-based coating composition characterized by being at least one selected .
2. Nitrogen-containing unsaturated monomer (A) having hydrogen bonding in thermosetting acrylic resin composition
Is an N-methacryloyloxyethyl-N′-ethylurea and / or N-methacryloyloxyethyl-N′-butylurea.
3. Nitrogen-containing unsaturated monomer (A) having hydrogen bonding in thermosetting acrylic resin composition
Item 3. The aqueous coating composition according to Item 1 or 2, wherein the mass ratio of the unsaturated monomer (B) is from 1/99 to 50/50.

  The aqueous coating composition of the present invention contains an acrylic resin that is resistant to thermal yellowing and has hydrogen bonding properties, and a thickener that exhibits hydrophobic interaction with the acrylic resin composition. An aqueous solution or aqueous dispersion can be obtained. In particular, it has a preferable effect of suppressing run-off (sagging) of the coating film during setting of the coating film after painting (in the case of baking-drying type paint) or curing (mainly in the case of room temperature to low-temperature drying type paint). In addition, the water-based coating composition of the present invention is less likely to cause repellency and dents, has an excellent finished appearance of the coating film, and is a cured coating film having excellent water resistance since it is made of an acrylic resin using a hydrogen bonding monomer having low hydrophilicity. Can be obtained.

Hereinafter, the present invention will be described in more detail.
Thermosetting acrylic resin composition
The thermosetting acrylic resin composition used in the present invention is one or more selected from an ethylenically unsaturated monomer having a urethane bond, an ethylenically unsaturated monomer having an imide bond, and an ethylenically unsaturated monomer having a urea bond. It is obtained by copolymerizing a nitrogen-containing unsaturated monomer (A) having the following hydrogen bonding properties and an unsaturated monomer (B) other than the unsaturated monomer (A).

Nitrogen-containing unsaturated monomer (A)
Ethylenically unsaturated monomer having urethane bond
Examples of the ethylenically unsaturated monomer having a urethane bond include commercially available monomers or synthetic monomers. Commercially available monomers include U-4HA, U-6HA, U-6LPA and the like (product of Shin-Nakamura Chemical Co., Ltd.). Synthetic monomers can be obtained by known methods. For example, the method of making an isocyanate compound and a hydroxyl group containing compound react can be mentioned. Furthermore, the combinations of starting compounds can be classified into two depending on which compound has an unsaturated group. One is a combination of an isocyanate compound having an unsaturated group and a hydroxyl group-containing compound, for example, 2-methacryloyloxyethyl isocyanate (trade name Karenz MOI) as an isocyanate having an unsaturated group, and the isocyanate group was blocked with MEK oxime. Products (trade name Karenz MOI-BM), those whose isocyanate groups are blocked with pyrazole (trade name Karenz MOI-BP), 2-acryloyloxyethyl isocyanate (trade name Karenz AOI) (above, manufactured by Showa Denko KK), etc. Can be used. The hydroxyl group-containing compound is not particularly limited, but for example, methanol, ethanol, propanol, butanol, pentanol, hexanol, cyclohexanol, heptanol, octanol, nonanol, decanol, undecanol, dodecanol, tridecanol, tetradecanol, pentadecane Alkanols such as decanol, hexadecanol, 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 polyoxypropylene monomer Ether group-containing monools such as ether; 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-hexane Diols such as diol, 2,2,4-trimethyl-1,3-pentanediol, hydroxypivalic acid-neopentyl glycol ester, dimethylolpropanoic acid, dimethylolbutanoic acid; Polyols such as ethane, trimethylolpropane, 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; A ring-opening adduct of a compound having an amino group and ethylene oxide, propylene oxide, tetrahydrofuran, lactone and / or cyclocarbonate; a reaction product of a compound having both an amino group and a hydroxyl group in one molecule and an epoxy group-containing compound; Reaction product of polyisocyanate with compound having both amino group and hydroxyl group in one molecule; hydroxyl group-containing polyester resin, hydroxyl group-containing polyurethane resin, hydroxyl group-containing polycarbonate resin, hydroxyl group Yes vinyl polymer, known polyols such as epoxy resins. These may be used alone or in combination of two or more.

  Among these, a combination of 2-methacryloyloxyethyl isocyanate and an alkanol having 2 to 8 carbon atoms such as ethanol, propanol, butanol, pentanol, hexanol, cyclohexanol, heptanol, and octanol is preferable from the viewpoint of stability during the reaction.

  The other is a combination of a hydroxyl group-containing compound having an unsaturated group and an isocyanate compound. Examples of the hydroxyl group-containing compound having an unsaturated group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meta ) Acrylic acid such as acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate or hydroxyalkyl ester of methacrylic acid having 2 to 8 carbon atoms; hydroxyl group content such as 2-hydroxyethyl (meth) acrylate Monoetherified products of unsaturated monomers and polyether polyols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol; (meth) acrylic acid and polyethers such as polypropylene glycol and polyethylene glycol A monoesterified product with a polyol; an adduct of an α, β-unsaturated carboxylic acid and a monoepoxy compound such as Cardura E10 (manufactured by Shell Chemical Co., Ltd.) or α-olefin epoxide; 2-hydroxyethyl (meth) acrylate; Ring-opening addition products with lactone compounds such as ε-caprolactone (for example, trade names “PLAXEL FA2”, “PLAXEL FM-3”, etc., manufactured by Daicel Corporation) and the like, and as the isocyanate compound, for example, tetramethylene isocyanate Aliphatic monoisocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate and isophorone diisocyanate Socynate; Alicyclic diisocyanates such as 4.4'-methylenebis (cyclohexyl isocyanate) and isophorone diisocyanate; Aromatic diisocyanates such as xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, and polyphenylmethane diisocyanate (hereinafter referred to as polymeric MDI); Monoisocyanates obtained by reacting one of diisocyanates with active hydrogen-containing compounds such as monoalcohols and amines in advance; and similar compounds such as isocyanurates and burettes of the diisocyanates. A mixture of more than one species can also be used.

  Among them, one obtained by reacting one of the diisocyanates with an amine compound is an isocyanate having a urea bond in the molecule, and the reaction product of this with a hydroxyl group-containing unsaturated monomer is an ethylenic compound having both a urethane bond and a urea bond in the molecule. It becomes an unsaturated monomer. In addition, as a synthesis order at this time, firstly, a hydroxyl group-containing compound can be obtained by reacting a diisocyanate with an active hydrogen-containing compound such as monoalcohol or amine and then reacting the remaining isocyanate group with a hydroxyl group-containing unsaturated monomer. After reacting the unsaturated monomer and diisocyanate, the remaining isocyanate group and the active hydrogen-containing compound may be reacted. It is also possible to react the above three at the same time. However, in this case, the product becomes a mixture, which is not advantageous because it needs to be purified.

  Among the above, a combination of a hydroxyalkyl ester having 2 to 8 carbon atoms of acrylic acid or methacrylic acid and a monoisocyanate obtained by reacting one of diisocyanates with an active hydrogen-containing compound such as monoalcohol or amine in advance is a reaction time. It is preferable from the viewpoint of stability and a large number of hydrogen bonding sites.

An ethylenically unsaturated monomer having an imide bond
Examples of the ethylenically unsaturated monomer having an imide bond include hexahydrophthalimide ethyl acrylate (Aronix M-140: product of Toa Gosei Co., Ltd.), hexahydrophthalimide propylene acrylate, and the like. Moreover, this monomer can also be synthesize | combined and the synthesis | combining method is clarified by the following well-known literature (1)-(5), 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.

Ethylenically unsaturated monomers having urea bonds
An ethylenically unsaturated monomer having a urea bond can be obtained by synthesis. The synthesis can be performed, for example, by reacting an isocyanate compound having an unsaturated group with an amine compound.

  As the isocyanate having an unsaturated group, the aforementioned 2-methacryloyloxyethyl isocyanate (trade name Karenz MOI), the isocyanate group of the 2-methacryloyloxyethyl isocyanate blocked with MEK oxime (trade name Karenz MOI-BM), the same Pyrazole block products can be used, and examples of amine compounds include monomethylamine, dimethylamine, trimethylamine, monoethylamine, triethylamine, monoisopropylamine, diisopropylamine, butylamine, diethylenetriamine, triethylenetetramine, monoethanolamine, diethanolamine, triethanolamine, and the like. Ethanolamine, monoisopropanolamine, diisopropanolamine, dimethylethanolamine, 2-aminomethyl Propanol, morpholine, methylmorpholine, it may be used piperazine.

  Of these, a combination of 2-methacryloyloxyethyl isocyanate and a primary amine compound such as monoethylamine, monoisopropylamine, and butylamine is preferable from the viewpoint of stability during the reaction. Among them, 2-methacryloyloxyethyl isocyanate and ethylamine are preferred. N-methacryloyloxyethyl-N′-butylurea obtained by reacting N-methacryloyloxyethyl-N′-ethylurea, 2-methacryloyloxyethylisocyanate and butylamine obtained by reacting is particularly preferable.

  Also listed in the stage of ethylenically unsaturated monomers having urethane bonds is "reactive product of one of diisocyanates and amines having urea bonds in the molecule and hydroxyl group-containing unsaturated monomers" It can be suitably used.

Unsaturated monomer (B)
The unsaturated monomer (B) is one or more hydrogen bonds selected from the ethylenically unsaturated monomer having a urethane bond, the ethylenically unsaturated monomer having an imide bond, and the ethylenically unsaturated monomer having a urea bond. It is an unsaturated monomer other than the nitrogen-containing unsaturated monomer (A) having the following, and monomers shown below can be used.

(1): methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, i- (meth) acrylic acid Butyl, t-butyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, decyl (meth) acrylate, lauryl (meth) acrylate, C1-C30 alkyl ester or cycloalkyl ester of acrylic acid or methacrylic acid such as stearyl (meth) acrylate, cyclohexyl (meth) acrylate, and isobornyl (meth) acrylate.
(2): C2-C18 alkoxyalkyl ester of acrylic acid or methacrylic acid such as methoxybutyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxybutyl (meth) acrylate; acetoacetoxyethyl (meta ) Acrylate.
(3): Vinyl aromatic compounds such as styrene, α-methylstyrene, vinyltoluene, and p-chlorostyrene.
(4): C2-C8 hydroxyalkyl ester of acrylic acid or methacrylic acid such as 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate.
(5): A monomer represented by an adduct of a hydroxyalkyl ester of acrylic acid or methacrylic acid and ε-caprolactone, for example, Plaxel FM-3 (manufactured by Daicel Chemical Industries, “Placcel” is a trade name).
(6): Polyalkylene glycol mono (meth) acrylates, hydroxyalkyl vinyl ethers.
(7): Glycidyl (meth) acrylate, diglycidyl fumarate, allyl glycidyl ether, ε-caprolactone-modified glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, etc. An epoxy group-containing unsaturated monomer.
(8): Perfluoroalkyl esters of acrylic acid or methacrylic acid, such as perfluorobutylethyl (meth) acrylate, perfluoroisononylethyl (meth) acrylate, and perfluorooctylethyl (meth) acrylate.
(9): Olefin such as ethylene, propylene, butylene and pentene.
(10): Diene compounds such as butadiene, isoprene and chloroprene.
(11): Fluoroolefins such as trifluoroethylene, tetrafluoroethylene, and vinylidene fluoride.
(12): Vinyl esters and propenyl esters of fatty acids having 1 to 20 carbon atoms such as vinyl acetate, vinyl propionate, vinyl caprate, Veova monomer (made by Shell Chemical Co., Ltd., vinyl ester of branched higher fatty acid), isopropenyl acetate, etc. Vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, butyl vinyl ether, octyl vinyl ether, cyclohexyl vinyl ether, phenyl vinyl ether, benzyl vinyl ether, and the like.
(13): acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid, 2-carboxyethyl (meth) acrylate, 2-carboxypropyl (meth) acrylate, 5-carboxypentyl (meth) acrylate, etc. Carboxyl group-containing unsaturated monomer.
(14): Hydrolyzable alkoxysilyl group-containing unsaturated monomers such as vinyltriethoxysilane, vinyltrimethoxysilane, vinyltris (methoxyethoxy) silane, γ-methacryloyloxypropyltrimethoxysilane, 2-styrylethyltrimethoxysilane.
(15): Aminoalkyl (meth) acrylates such as N, N-dimethylaminoethyl (meth) acrylate and Nt-butylaminoethyl (meth) acrylate.
(16): Acrylamide, methacrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide Polymerizable amides such as N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N, N-dimethylaminoethyl (meth) acrylamide, diacetone acrylamide; 1-vinyl-2-pyrrolidone, 4-vinylpyridine, (meth) acryloylmorpholine and the like.
(17): sulfonic acid monomers such as vinyl sulfonic acid, methallyl sulfonic acid, sulfoethyl (meth) acrylate, styrene sulfonic acid, 2-acrylamido-2-methylpropane sulfonic acid, and salts thereof;
(18) An esterified product of a hydroxyl group-containing monomer such as 2- (meth) acryloyloxyethyl acid phosphate and a phosphoric acid compound.
(19): A phosphoric acid-containing monomer such as a product obtained by adding a phosphoric acid compound to an epoxy group such as glycidyl (meth) acrylate.
(20): Polymerizable nitriles such as acrylonitrile and methacrylonitrile.
(21): A polymerizable amine such as allylamine.
(22): Acid anhydride monomers such as maleic anhydride and itaconic anhydride.
(23): Divinylbenzene, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, polypropylene glycol di (Meth) acrylate, neopentyl glycol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, bisphenol A ethylene oxide modified di (meth) acrylate, bisphenol Di (meth) acrylate modified with A and propylene oxide, 2-hydroxy-1-acryloxy-3-methacryloxypropane, tricyclodecane dimethano Distearate (meth) acrylate, di (meth) acryloyloxyethyl acid phosphate; KAYARAD HX-220, the 620, the R-604, MANDA (manufactured by Nippon Kayaku Co. product) bifunctional polymerizable monomers such as.
(24): Tri (meth) acrylate modified with trimethylolpropane tri (meth) acrylate, trimethylolpropane and ethylene oxide, tri (meth) acrylate modified with trimethylolpropane and propylene oxide, glycerol tri (meth) Tri (meth) acrylate modified with acrylate, glycerol and ethylene oxide, modified tri (meth) acrylate with glycerol and propylene oxide, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, isocyanuric acid and ethylene oxide Trifunctional or higher functional polymerizable monomers such as modified tri (meth) acrylate and dipentaerythritol hexa (meth) acrylate.

  Nitrogen-containing unsaturated monomer having one or more hydrogen bonds selected from ethylenically unsaturated monomers having urethane bonds, ethylenically unsaturated monomers having imide bonds, and ethylenically unsaturated monomers having urea bonds (A ) And the weight ratio of the unsaturated monomer (B) are preferably between 1/99 and 50/50 (including end values). If the unsaturated monomer (A) is less than 1/99, sufficient hydrogen bonding effects such as thickening may not be obtained. On the other hand, when the amount of the unsaturated monomer (A) exceeds 50/50, the effect of hydrogen bonding is too strong, and problems such as pseudo gelation of an aqueous solution or aqueous dispersion may occur.

  Considering that the unsaturated monomer (B) brings about an interaction with a thickener described later, at least a part of the unsaturated monomer (B) contains a monomer that can contribute to the hydrophobic interaction. When the total of the saturated monomer (A) and the unsaturated monomer (B) is 100 parts by weight, the content is preferably 1 to 50 parts by weight. Examples of such monomers include, for example, the alkyl ester or cycloalkyl ester having 4 to 30 carbon atoms of the above-mentioned (1) acrylic acid or methacrylic acid alkyl ester or cycloalkyl ester having 4 to 30 carbon atoms, (3) Examples include vinyl aromatic compounds.

  The thermosetting acrylic resin composition used in the present invention can be produced by copolymerizing the unsaturated monomer (A) and the unsaturated monomer (B) by a known method such as an emulsion polymerization method or a solution polymerization method. I can do it. For example, a thermosetting acrylic resin emulsion obtained by an emulsion polymerization method, a thermosetting water-soluble acrylic resin obtained by a solution polymerization method, and the like are mentioned, and an acrylic resin emulsion obtained by an emulsion polymerization method when used as an aqueous paint. It is preferable. In particular, it is considered that the effects derived from the hydrogen bonding properties of the monomer (A) are often high in cost compared to the viewpoint that it is manifested by the presence of the monomer (A) component on the surface of the emulsion particles and general commercial monomers. From the viewpoint of securing the concentration of the particle surface while suppressing the total amount of the monomer (A) used, a core-shell emulsion containing the monomer (A) in the shell part is preferable. In this case, the mass ratio of the core to the shell is preferably 1/9 to 9/1, more preferably 5/5 to 9/1, from the viewpoint of cost, and the content of the monomer (A) in the shell portion is It is preferable that the amount is 3 to 70% by mass with respect to the total amount of the shell in order to obtain an effect derived from hydrogen bonding properties. In addition, from the viewpoint of mechanical stability of the core-shell emulsion, the core part is preferably crosslinked in advance with a polyfunctional monomer, and the bifunctional polymerizable monomer (23) and (24 It is preferable to contain 5% by mass or less of one or more monomers selected from among the trifunctional or higher functional polymerizable monomers (1) based on the total amount of the core.

  The production of such a core-shell emulsion involves emulsion polymerization of a mixture of two or more monomers (B), which may contain the monomer (A), to obtain an emulsion of the core part (co) polymer, and then into this emulsion. Adding a monomer mixture comprising monomer (A) (preferably 3 to 70% by mass) and monomer (B) (preferably 30 to 97% by mass), and further emulsion polymerization to prepare a shell copolymer. Can be obtained by:

  Emulsion polymerization for preparing an emulsion of the core (co) polymer 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 an emulsifier.

  As the emulsifier, an anionic emulsifier and a nonionic emulsifier are suitable. Examples of the anionic emulsifier include sodium salts and ammonium salts such as alkylsulfonic acid, alkylbenzenesulfonic acid, and alkylphosphoric acid. Nonionic emulsifiers include, for example, polyoxyethylene oleyl ether, polyoxyethylene stearyl ether, polyoxyethylene lauryl ether, polyoxyethylene tridecyl ether, polyoxyethylene phenyl ether, polyoxyethylene nonylphenyl ether, polyoxyethylene Examples include ethylene octyl phenyl ether, polyoxyethylene monolaurate, polyoxyethylene monostearate, polyoxyethylene monooleate, sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, and polyoxyethylene sorbitan monolaurate. .

  Also, a polyoxyalkylene group-containing anionic emulsifier having an anionic group and a polyoxyalkylene group such as a polyoxyethylene group or a polyoxypropylene group in one molecule; an anionic group and a radically polymerizable unsaturated group in one molecule It is also possible to use reactive anionic emulsifiers having Of these, it is preferable to use a reactive anionic emulsifier.

  Examples of the reactive anionic emulsifier include sodium salts and ammonium salts of sulfonic acid compounds having radically polymerizable unsaturated groups such as (meth) allyl groups, (meth) acryloyl groups, propenyl groups, and butenyl groups. . Among these, an ammonium salt of a sulfonic acid compound having a radically polymerizable unsaturated group is preferable because the resulting coating film has excellent 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. As a commercial item of the ammonium salt of the sulfonic acid compound having the radical polymerizable unsaturated group and the polyoxyalkylene group, for example, “AQUALON KH-10” (trade name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), “SR” -1025A "(trade name, manufactured by ADEKA Corporation).

  The amount of the emulsifier used is preferably about 0.1 to 15% by mass, more preferably about 0.5 to 10% by mass, and about 1 to 5% by mass based on the total amount of all monomers used. Further preferred.

  Examples of the polymerization initiator include benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert-butyl peroxide, tert-butyl peroxylaurate, and tert-butyl peroxy. Organic peroxides such as isopropyl carbonate, tert-butyl peroxyacetate, diisopropylbenzene hydroperoxide; azobisisobutyronitrile, azobis (2,4-dimethylvaleronitrile), azobis (2-methylpropiononitrile), azobis (2-methylbutyronitrile), 4,4'-azobis (4-cyanobutanoic acid), dimethylazobis (2-methylpropionate), azobis [2-methyl-N- (2-hydro Cyethyl) -propionamide], azo compounds such as azobis {2-methyl-N- [2- (1-hydroxybutyl)]-propionamide}; persulfates such as potassium persulfate, ammonium persulfate, sodium persulfate, etc. Is mentioned. 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.

  In general, the amount of the polymerization initiator used is preferably about 0.1 to 5% by mass, more preferably about 0.2 to 3% by mass, based on the total mass of all monomers used. 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.

  In the core-shell emulsion, a monomer mixture composed of the monomer (A) and the monomer (B) is added to the core (co) polymer emulsion obtained above and further polymerized to form a shell copolymer. Can be obtained by: From the viewpoint of the mechanical stability of the emulsion, a part of the monomer (B) includes (13) the carboxyl group-containing unsaturated monomer or (17) the sulfonic acid monomer and its salt or (19) in the above examples. It is preferable that an acid group-containing monomer selected from phosphoric acid-containing monomers is included, and it is particularly preferable that a carboxyl group-containing unsaturated monomer (13) is included.

  The monomer mixture for forming the shell copolymer may appropriately contain components such as the polymerization initiator, chain transfer agent, reducing agent, and emulsifier 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, for example, the monomer mixture or the emulsion thereof is added all at once or gradually and added to the core (co) polymer emulsion, A method of heating to an appropriate temperature while stirring can be mentioned.

  The core-shell emulsion thus obtained has, as a core part, a monomer mixture comprising the monomer (B) which may contain the monomer (A), and a monomer comprising the monomer (A) and the monomer (B). It has a multilayer structure in which a copolymer of the mixture is used as a shell part.

  The core-shell emulsion thus obtained can have an average particle size of about 10 to 1000 nm, particularly about 20 to 500 nm.

  In the present specification, the average particle size of the core-shell emulsion is a value measured at 20 ° C. after diluting with deionized water by a conventional method using a submicron particle size distribution analyzer. As the submicron particle size distribution measuring device, for example, “COULTER N4 type” (trade name, manufactured by Beckman Coulter, Inc.) can be used.

  In order to improve the mechanical stability of the particles of the core-shell emulsion, it is desirable to neutralize acidic groups such as carboxyl groups that the emulsion preferably has with a neutralizing agent. The neutralizing agent is not particularly limited as long as it can neutralize acidic groups. 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 neutralized emulsion or the aqueous coating composition containing the emulsion is about 6.5 to 9.0.

Water-based paint composition
The water-based coating composition of the present invention contains the thermosetting acrylic resin composition and a thickener. If necessary, other paint additives, neutralizing agents, organic solvents, curing agents, modifying resins, pigments and the like can be blended.

Thickener The thickener used in the present invention is selected from the group consisting of an ethylenically unsaturated monomer having a urethane bond, an ethylenically unsaturated monomer having an imide bond, and an ethylenically unsaturated monomer having a urea bond. It is a thickener which interacts with the thermosetting acrylic resin composition characterized by copolymerizing one or more selected nitrogen-containing unsaturated monomers (A) having hydrogen bonding properties.

  Non-Patent Document 1 includes substances having various structures as conventional flow control agents for aqueous coating compositions. That is, inorganic substances mainly composed of viscosity minerals such as bentonite and montmorillonite, celluloses that are natural high molecular weight substances such as carboxyethyl cellulose and ethyl cellulose, vinyls composed of water-soluble polymers such as polyvinyl alcohol and polyvinyl pyrrolidone, (Meth) acrylic acid monomer as a monomer component, polyacrylic acid-based, polyether-modified urethane compound, hydrophobic-modified polyoxyethylene polyurethane copolymer and the like, polyamide-based using a salt of polyamide wax amine, And urea-based compounds such as urethane-urea-based compounds.

  Among these thickeners, when a thickener exhibiting a hydrophobic interaction is used, the coating film of the aqueous coating composition of the present invention exhibits a high finish with little repellency and dents.

  The reason why the finish is improved by the combination of the specific resin and the specific thickening agent has not been elucidated in detail, but is considered to be due to the following reasons.

  The thickener used in the aqueous coating composition exhibits a thickening effect in an aqueous solution or aqueous dispersion mainly due to intermolecular hydrogen bonding force, and in particular, a thermosetting property with hydrogen bonding which is the binder of the present invention. When combined with an acrylic resin composition, a high thickening effect is exhibited.

  However, since the hydrogen bond force is a force that always acts between molecules caused by molecular polarization, its strength does not change depending on the magnitude of the displacement speed, so thickening using hydrogen bond force is at low shear. It also shows high viscosity at high shear. If the viscosity of the coating liquid is too high, poor coating workability such as difficulty in atomizing the paint or poor elongation occurs during spray coating or brush coating. And to reduce this, if you increase the dilution rate and paint, the resistance to repellency and dents will decrease when set after setting. The viscosity of the coated film is insufficient due to dilution, and local abnormal flow caused by a small amount of low-polarity contaminants mixed in from the environment, i.e. dot-like repellency and dents on the surface of the film occurs. Conceivable.

  Among the thickeners for aqueous coating compositions, there are thickeners that utilize hydrophobic interactions. The “hydrophobic interaction” here is the “aggregation” of hydrophobic molecules in a highly polar medium called water. Here, if all parts of the molecule are aggregated, non-dissolution = separation precipitation / precipitation, but if some of the molecular segments are aggregated locally, the solute molecules are dissolved or dispersed by the hydrophilic segment part. While maintaining the state, the molecules are connected by local aggregation, thereby increasing the viscosity. This is considered to be a mechanism of thickening by hydrophobic interaction.

  Aggregation of molecules is a phenomenon expressed by the close proximity of molecules = force, so that hydrophobic interaction (due to viscosity) is difficult to develop when the displacement rate due to shearing is large. This brings about a preferable flow characteristic (thixotropy) in which a thickening effect does not appear when the displacement speed is high and a viscosity appears when the displacement speed is low. In addition, this hydrophobic interaction effect is synergistic with the hydrophobic interaction with the binder, so that the coating workability such as low viscosity when coating as paint, atomization during spray coating, nob during brush coating, etc. It is considered that the viscosity is sufficiently increased during setting, so that it is possible to obtain a high finish without coating defects such as repellency and dents.

  Particularly preferred as a thickener exhibiting such hydrophobic interaction is a polyacrylic acid thickener copolymerized with a hydrophobic monomer, a polyurethane thickener having a hydrophobic chain in the molecule, and at least one main chain. Urethane-urea thickener whose part is a hydrophobic urethane chain, amide-urea thickener whose main chain is at least part of a hydrophobic amide chain, and at least part of the main chain is a hydrophobic urethane chain More preferred are urethane-urea thickeners, and amide-urea thickeners in which at least part of the main chain is a hydrophobic amide chain.

  As such a thickener, BYK-425 (urea-modified urethane compound: manufactured by BYK-Chemie), BYK-420 (urethane-urea compound: manufactured by BYK-Chemie), BYK-430 (amide-urea compound: BYK-Chemie) Manufactured), SN thickener-660T, SN thickener-665T (urethane system: manufactured by Sannopco), RHEOLATE216 (urethane-urea compound: manufactured by ELEMENTIS), Primal RM-12W, primal RM-895 (urethane system: manufactured by Dow Chemical Company) ) Etc. are commercially available.

  The addition amount of the thickener used in the present invention is appropriately determined depending on the required rheological properties of the paint, but in general, an ethylenically unsaturated monomer having a urethane bond, an ethylenically unsaturated monomer having an imide bond, and 0.03 mass% with respect to the thermosetting acrylic resin copolymerized with one or more nitrogen-containing unsaturated monomers (A) selected from ethylenically unsaturated monomers having urea bonds. A range of -5%, more preferably 0.1-2% is preferred. If the thickener is less than this range, sufficient rheology control effect may not be obtained. If the thickener is more than this range, the viscosity of the paint becomes too high and atomization during spray coating is possible. The coating workability may be hindered, for example, due to inadequate or poor paint coating during brush painting.

  Other paint additives include dispersants such as potassium phosphates, sodium salts, ammonium salts, anionic or nonionic surfactants of condensed phosphoric acid such as pyrophosphoric acid, tripolyphosphoric acid and hexametaphosphoric acid; antifoaming agents, antiseptics Agents, anti-fungal agents and the like. Moreover, a ultraviolet absorber and / or a light stabilizer can also be mix | blended. Examples of the ultraviolet absorber include 2- (5-methyl-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2 -(3,5-di-tert-butyl-2-hydroxyphenyl) benzotriazole, 2- (3-tert-butyl-5-methyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3 5-di-t-butyl-2-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3,5-di-t-amyl-2-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-5) Benzotriazoles such as' -t-octylphenyl) benzotriazole; 2,4-dihydroxy-benzophenone, 2-hydroxy- -Methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, benzophenones such as 2-hydroxy-4-n-dodecyloxybenzophenone, and the like. Examples of the light stabilizer include bis (2,2,6,6). 6-tetramethyl-4-piperidyl) sebacate, 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butyl, bis (1,2,2,6,6-malonate) Pentamethyl-4-piperidyl), bis (2,2,6,6-tetramethyl-4-piperidyl) succinate and the like.

  Examples of the neutralizing agent include the basic compounds described above.

  There is no restriction | limiting in particular as an organic solvent, Hydrophilic solvents, such as alcohol type and ester type, or hydrophobic solvents, such as hydrocarbon type, can be used.

  Moreover, the hardening | curing agent which can react with the functional group in a thermosetting acrylic resin can also be used together as needed. Examples of such curing agents include amino resins, polyisocyanate compounds, blocked polyisocyanate compounds, epoxy group-containing compounds, carboxyl group-containing compounds, carbodiimide group-containing compounds, and the like. These may be water-soluble or hydrophobic.

  Furthermore, a water-soluble or water-dispersible modifying resin may be included. Examples of the modifying resin include polyurethane resins, polyester resins, acrylic resins other than the thermosetting acrylic resins, alkyd resins, silicon resins, fluororesins, and epoxy resins. These modifying resins can be used singly or in combination of two or more. In particular, it is preferable to include a water-soluble or water-dispersible polyurethane resin from the viewpoints of coating workability, coating film water resistance, and the like.

  The aqueous coating composition of the present invention can contain a pigment. As the pigment, any one or two or more of a color pigment, an extender pigment and a glitter pigment can be used.

  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.

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

  Examples of the bright pigment include aluminum, vapor-deposited aluminum, copper, zinc, brass, nickel, aluminum oxide, mica, aluminum oxide coated with titanium oxide or iron oxide, mica coated with titanium oxide or iron oxide, and the like. Can be mentioned. Of these, aluminum and evaporated aluminum are particularly preferable. The aluminum and vapor-deposited aluminum include non-leafing type and leafing type aluminum, both of which can be used. The glitter pigment is preferably in the form of flakes.

  The aqueous coating composition of the present invention can form a coating film having an excellent appearance by coating on various objects to be coated.

  The material of these objects to be coated is not particularly limited. For example, metal materials such as iron, aluminum, brass, copper, stainless steel, tinplate, galvanized steel, alloyed zinc (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; inorganic materials such as glass, cement and concrete; Wood; fiber materials (paper, cloth, etc.) and the like. Of these, metal materials are preferred.

  The article to be coated may be one in which an undercoat coating film is formed on a base material such as the above metal material. In addition, an undercoat coating film and an intermediate coating film may be sequentially formed on the substrate. When the base material is a metal material, it may have been subjected to surface treatment such as phosphate treatment, chromate treatment, complex oxide treatment in advance before forming an undercoat film on the base material. Good.

  The coating method of the aqueous coating composition of the present invention is not particularly limited, and examples thereof include brush coating, roller coating, air spray coating, airless spray coating, rotary atomization coating, and curtain coat coating. A wet coating film can be formed by these coating methods.

  The wet coating film can be cured by applying the composition of the present invention to an object to be coated and then heating it. 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. When the object to be coated is a metal material, the heating temperature is usually preferably about 80 to 180 ° C, more preferably about 100 to 170 ° C, and further 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.

  Thus, the aqueous coating composition of the present invention is excellent in rheocon properties, finish properties and repellency resistance.

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

Synthetic monomer production example 1 of an ethylenically unsaturated monomer having a urea bond
An empty four-necked flask equipped with a stirrer, thermometer, drying tube and dropping funnel was placed in an oil bath equipped with a heating and cooling device. First, 40 parts of tetrahydrofuran and 52.9 parts of 2-methacryloyloxyethyl isocyanate were charged into the flask, and the temperature of the flask contents was adjusted to 15 ° C. by cooling the oil bath. Next, 37 parts of a 37.8% methanol solution of ethylamine was added dropwise to the flask with stirring for 1 hour while adjusting the oil bath temperature so that the temperature of the contents was maintained at 20 ° C. or lower, and the mixture was further maintained for 2 hours. The amine and isocyanate were reacted. Thereafter, the NCO value (Note 1) of the contents was measured and confirmed to be 1 or less. Next, the content was heated to 60 ° C. and solvent removal (tetrahydrofuran) was performed under reduced pressure to obtain an ethylurea group-containing polymerizable unsaturated monomer A-1.

(Note 1) NCO value: The amount of isocyanate group (mg) contained in 1 g of the polymerizable unsaturated monomer, followed by the following measurement method.
A sample (about 1 g) is weighed correctly in an Erlenmeyer flask, and 10 ml of dioxane is added. The dissolved sample is heated to 50 ° C., 10 ml of a properly weighed N / 5 dibutylamine-dioxane solution is added, and the mixture is stirred for 2 minutes to react the sample with dibutylamine. Next, after adding 2 to 3 bromophenol blue-ethyl alcohol solutions, titration is performed with an N / 10 hydrochloric acid solution, and the end point is when the solution changes from blue to yellow-green. The NCO value of the sample is calculated according to the following formula.

Formula N = {0.1 × 42 × (A−B) × f} /0.01×S×W}
Here, N: NCO value (mg number of NCO contained in 1 g of sample)
A: Amount of N / 10 hydrochloric acid solution used to neutralize blank N / 5 dibutylamine-dioxane solution (ml)
B: Amount of N / 10 hydrochloric acid solution used for titration of sample (ml)
f: Factor of N / 10 hydrochloric acid solution S: Residue of sample heated (%)
W: Amount of sample (g)
42: Molecular weight of isocyanate group (NCO).

Monomer Production Example 2
The amount of 2-methacryloyloxyethyl isocyanate charged in Production Example 1 was changed to 51.2 parts, and 24.1 parts of butylamine was added dropwise instead of 37 parts of a 37.8% methanol solution of ethylamine. Was maintained at 35 ° C. instead of 20 ° C., and synthesis was carried out in the same manner as in Production Example 1 to obtain a butylurea group-containing polymerizable unsaturated monomer A-2.

Monomer Production Example 3
The amount of 2-methacryloyloxyethyl isocyanate charged in Production Example 1 was changed to 51.2 parts, and 19.5 parts of isopropylamine was added dropwise instead of 37 parts of a 37.8% methanol solution of ethylamine. Synthesis was carried out in the same manner as in Production Example 1 except that the temperature was maintained at 35 ° C., thereby obtaining isopropylurea group-containing polymerizable unsaturated monomer A-3.

Monomer Production Example 4
An empty four-necked flask equipped with a stirrer, a thermometer, a drying tube, an air introduction tube and a dropping funnel was placed in an oil bath equipped with a heating and cooling device. First, 42.9 parts of 2-hydroxyethyl methacrylate and 0.039 parts of p-methoxyphenol were charged into a flask, and the contents were heated to 60 ° C. while introducing dry air. Further, 66.6 parts of isophorone diisocyanate was added, stirred for 2 hours, then heated to 80 ° C. and reacted for 1 hour. Thereafter, the contents were cooled to 10 ° C., and 50 parts of tetrahydrofuran was added. Thereafter, 19.7 parts of butylamine was added dropwise over 1 hour while maintaining the temperature of the contents not exceeding 20 ° C. Next, the temperature was raised to 60 ° C., and the solvent was removed under reduced pressure (tetrahydrofuran) to obtain a butylurea group-containing polymerizable unsaturated monomer A-4.

Synthetic monomer production example 5 of an ethylenically unsaturated monomer having a urethane bond
An empty four-necked flask equipped with a stirrer, a thermometer, a drying tube, an air introduction tube and a dropping funnel was placed in an oil bath equipped with a heating and cooling device. First, 67.7 parts of 2-methacryloyloxyethyl isocyanate and 0.40 part of p-methoxyphenol were charged into a flask, and the temperature was raised to 50 ° C. while introducing dry air. Next, 32.3 parts of butanol was added dropwise over 1 hour while maintaining the temperature at 60 ° C. or lower while stirring, and further maintained at 60 ° C. for 1 hour with stirring. Thereafter, the temperature was raised to 100 ° C. and the reaction was performed for 1 hour to obtain a butylurethane group-containing polymerizable unsaturated monomer A-5.

Synthetic monomer production example 6 of ethylenically unsaturated monomer having imide bond
An empty four-necked flask equipped with a stirrer, thermometer, drying tube, air introduction tube and water separator was placed in an oil bath equipped with a heating and cooling device. First, methacrylic acid 52.4 parts, N-hydroxyethylphthalimide 47.6 parts, toluene 64.2 parts, p-methoxyphenol 0.08 parts, p-toluenesulfonic acid monohydrate 4.7 parts in a flask. 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%. It cooled to 10 degreeC using ice water, the deposited crystal | crystallization was filtered, and ethylenically unsaturated monomer A-6 (phthalimidoethyl methacrylate) which has an imide bond was obtained.

Production of thermosetting acrylic emulsion
Production Example 1
130 parts of deionized water, “Aqualon KH-10” (trade name) in an empty reaction vessel equipped with a stirrer, thermometer, thermostat, reflux condenser, nitrogen inlet tube and dropping device , Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene alkyl ether sulfate ester ammonium salt, active ingredient 97%) 0.52 part was charged, and the contents were heated to 80 ° C. with stirring and mixing under a nitrogen stream. Next, an amount corresponding to 1% of the total mass of the following monomer emulsion (1) and 5.3 parts of a 6% aqueous ammonium persulfate solution were added with stirring and maintained at 80 ° C. for 15 minutes. Thereafter, the remaining amount of the monomer emulsion (1) was dropped over 3 hours while maintaining the temperature at 80 ° C., and aging was performed for 1 hour after the completion of the dropping.

  Thereafter, the following monomer emulsion (2) was added dropwise over 1 hour while keeping the temperature of the content at 80 ° C., and after aging for 1 hour, 40 parts of 2-% (dimethylamino) ethanol aqueous solution (2- While adding (dimethylamino) ethanol (2.0 parts) to the reaction vessel over 1 hour, the contents were gradually cooled and the temperature of the contents was adjusted to 30 ° C. at the end of the addition. The thermosetting acrylic emulsion B-1 was obtained by the above process.

  The obtained emulsion is a core-shell type acrylic emulsion having a crosslinked core part, and is diluted with deionized water using an average particle size of 142 nm (submicron particle size distribution measuring device “COULTER N4 type” (manufactured by Beckman Coulter)). Measured at 20 ° C.), the solid content concentration was 30%. The hydroxyl value of the acrylic resin itself was 9.4 mgKOH / g, and the acid value was 14.3 mgKOH / g.

  Monomer emulsion (1): 46.2 parts of deionized water, 0.79 parts of “AQUALON KH-10”, 3.0 parts of ethylene glycol dimethacrylate, 64.0 parts of methyl methacrylate, and 10.0 of n-butyl acrylate The parts were mixed and stirred to obtain a monomer emulsion (1). This monomer emulsion (1) forms the core part of a core-shell type acrylic emulsion after polymerization.

  Monomer emulsion (2): 13.8 parts of deionized water, 0.24 part of “Aqualon KH-10”, 0.03 part of ammonium persulfate, 4.37 parts of methyl methacrylate, 4.37 parts of n-butyl acrylate, styrene 2 .98 parts, 2.19 parts of 2-hydroxyethyl methacrylate, 2.19 parts of methacrylic acid, and 6.9 parts of ethylurea group-containing polymerizable unsaturated monomer (A-1) obtained in Monomer Production Example 1 were mixed and stirred. Thus, a monomer emulsion (2) was obtained. This monomer emulsion (2) forms the shell part of a core-shell type acrylic emulsion after polymerization.

Production Examples 2-9, Production Examples 11-19
Thermosetting acrylic emulsions B-2 to B-19 are obtained in the same manner as in Example 1 except that the compositions of the monomer emulsions (1) and (2) are changed as shown in Tables 1 and 2 below. It was. Table 1 and Table 2 below show the solid content concentration, acid value, hydroxyl value and average particle size of the obtained thermosetting acrylic emulsions B-2 to B-19 together with Production Example 1.

Production Example 10
130 parts of deionized water, “Aqualon KH-10” (trade name) in an empty reaction vessel equipped with a stirrer, thermometer, thermostat, reflux condenser, nitrogen inlet tube and dropping device , Manufactured by Daiichi Kogyo Seiyaku Co., Ltd., polyoxyethylene alkyl ether sulfate ester ammonium salt, active ingredient 97%) 0.52 part was charged, and the contents were heated to 80 ° C. with stirring and mixing under a nitrogen stream. Next, an amount corresponding to 1% of the total mass of the following monomer emulsion (1) and 5.3 parts of a 6% aqueous ammonium persulfate solution were added with stirring and maintained at 80 ° C. for 15 minutes. Thereafter, the remaining amount of the monomer emulsion (1) was dropped over 3 hours while maintaining the temperature at 80 ° C., and aging was performed for 1 hour after the completion of the dropping. The thermosetting acrylic emulsion B-10 was obtained by the above process.

  Monomer emulsion (1): 60.0 parts of deionized water, 1.03 part of “AQUALON KH-10”, 3.0 parts of ethylene glycol dimethacrylate, 68.4 parts of methyl methacrylate, 14.4 parts of n-butyl acrylate , 3.0 parts of styrene, 2.19 parts of 2-hydroxyethyl methacrylate, 2.19 parts of methacrylic acid and 6.9 parts of ethylurea group-containing polymerizable unsaturated monomer (A-1) obtained in Monomer Production Example 1 An emulsion obtained by stirring.

Manufacture of thermosetting water-soluble acrylic resin
Production Example 20
35.0 parts of butyl cellosolve was charged in an empty reaction vessel equipped with a heating and cooling device and equipped with a stirrer, thermometer, thermostat, reflux condenser, nitrogen inlet tube and dropping device, and the temperature was adjusted to 125 ° C. under a nitrogen atmosphere. The temperature was raised, 30.0 parts of methyl methacrylate, 20.0 parts of n-butyl acrylate, 13.0 parts of styrene, 15.0 parts of 2-hydroxyethyl acrylate, 7.0 parts of acrylic acid, ethyl urea obtained in Production Example 1 A mixture of 15.0 parts of the group-containing polymerizable unsaturated monomer A-1 and 2.5 parts of 2,2′-azobisisobutyronitrile was added dropwise over 4 hours. Next, after aging for 30 minutes while bubbling nitrogen gas at 125 ° C., a mixture of 23.9 parts of butyl cellosolve and 0.5 part of 2,2′-azobisisobutyronitrile was added dropwise over 1 hour. Thereafter, the mixture was aged for 1 hour. The weight average molecular weight (Mw) of the obtained polymer was 14,000, and molecular weight distribution (Mw / Mn) was 2.1. The hydroxyl value was 64.7 mgKOH / g, and the acid value was 54.5 mgKOH / g. Further, 8.6 parts of dimethylaminoethanol was added to the obtained acrylic polymer solution with a solid content concentration of 55% to neutralize it, and then deionized water was gradually added to obtain a thermosetting acrylic with a solid content concentration of 30%. An aqueous dispersion C-1 of polymer was obtained.

Production Examples 21-30
Except having changed a monomer composition as shown in following Table 3, it carried out similarly to manufacture example 20, and obtained the water dispersion C-2 to C-11 of the thermosetting acrylic polymer. Table 3 below shows the solid content concentration, acid value, and hydroxyl value of the aqueous dispersions C-2 to C-11 of the obtained thermosetting acrylic polymer together with Production Example 20.

Production Example 1 of water-based coating composition
233 parts of thermosetting acrylic emulsion B-1 obtained in Production Example 1 (resin solid content 70 parts), melamine resin Cymel 272 (trade name: manufactured by Nippon Cytec Industries, Ltd., methyl-butyl mixed etherified melamine resin, solid 80%) and 37.5 parts (resin solid content 30 parts) and thickener BYK-425 (urea-modified urethane compound: active ingredient concentration 50%) 0.3 parts are uniformly mixed to form an aqueous coating composition D -1 was obtained.
Examples 2-22
Aqueous coating compositions D-2 to D-22 of Examples 2 to 22 were obtained in the same manner as in Example 1 except that the blending composition of the coating composition of Example 1 was changed as shown in Table 4 below. It was.

(Note 1) Bihijoule VPLS2310: trade name, manufactured by Sumika Bayer Urethane Co., Ltd., blocked polyisocyanate compound, solid content 38%
(Note 2) BYK-420: active ingredient concentration 52%
(Note 3) BYK-430: active ingredient concentration 30%.

Comparative Examples 1-22
Aqueous coating compositions D-23 to D-44 of Comparative Examples 1 to 22 were obtained in the same manner as in Example 1 except that the composition of the coating composition of Example 1 was changed as shown in Table 5 below. It was.

Evaluation test The aqueous coating composition obtained in each Example or Comparative Example was evaluated by the following test method. The evaluation results are shown in Tables 6 and 7 below.

(Test method)
Cracking property: The aqueous coating composition obtained in each Example or Comparative Example was applied on a glass plate with an applicator so that the dry film thickness was 35 ± 1 μm, and then pre-dried at 80 ° C. for 5 minutes. Then, it dried for 30 minutes at 140 degreeC using the hot air type dryer, and was set as the cured coating film. The cracking property of the obtained coating film was visually evaluated.

○: There is no crack.
X: Cracking is observed.

  Yellowing: The aqueous coating composition obtained in each example or comparative example was applied on a glass plate with an applicator so that the dry film thickness was 35 ± 1 μm, and then pre-dried at 80 ° C. for 5 minutes. Then, it dried for 30 minutes at 140 degreeC using the hot-air-type dryer, and was set as the cured coating film. The degree of yellowing before and after drying of the obtained coating film was visually evaluated.

○: No change
Δ: Yellowing is observed
X: Significant yellowing is observed.

  Solvent resistance: The aqueous coating composition obtained in each Example or Comparative Example was applied on a glass plate with an applicator so that the dry film thickness was 35 ± 1 μm, and then pre-dried at 80 ° C. for 5 minutes. Then, it dried for 30 minutes at 140 degreeC using the hot-air-type dryer, and was set as the cured coating film. Place about 2 ml of methyl ethyl ketone on the surface of the resulting coated plate, apply a fold of two layers of gauze (FC gauze manufactured by White Cross Co., Ltd.) and rub it 50 times with a stroke of 5 cm while pressing with the middle finger. The state of the coated plate was evaluated.

○: No changes such as scratches and gloss on the painted surface.
Δ: Fine scratches occurred after rubbing, and the gloss of the coated surface was lowered.
X: The coating film was broken and peeled off.

  Water resistance: The aqueous coating composition obtained in each Example or Comparative Example was applied on a glass plate with an applicator so that the dry film thickness was 20 ± 1 μm, and then pre-dried at 80 ° C. for 5 minutes. Then, it dried for 30 minutes at 140 degreeC using the hot-air-type dryer, and was set as the cured coating film. The obtained coated plate was immersed in warm water at 50 ° C. for 24 hours, then pulled up, wiped off water droplets on the surface, and then visually evaluated the state of the coated surface.

○: There is no change in the paint surface.
(Triangle | delta): Although whitening was seen on the coating surface, when it was left to stand for 24 hours, it returned to the original transparent coating surface.
X: The coating film was remarkably whitened and peeled off simply by rubbing lightly.

  Sagging property: After coating the aqueous coating composition obtained in each example or comparative example on a glass plate with an applicator so that the dry film thickness is 50 to 60 μm, the coating plate is held at an inclination angle of 30 degrees and the ambient temperature It left still at 80 degreeC for 30 minutes. The sagging condition of the coating film at that time was observed.

○: Sagging is not recognized.
Δ: Sagging occurs on part of the painted surface.
X: Sagging occurs over the entire surface of the coating film.

  Coating finish: The aqueous coating composition obtained in each Example or Comparative Example was further diluted with water to adjust the solid content concentration to 25%, and the dry film thickness was 30 ± on a 0.8 mm thick galvanized steel sheet. After spray coating to 1 μm, it was pre-dried at 80 ° C. for 5 minutes. Thereafter, it was dried at 140 ° C. for 30 minutes using a hot air drier to prepare a finish evaluation plate, and the finish was visually evaluated.

○: Smooth and free of coating defects.
Δ: Wrinkles / dents are scattered on the surface. (About 1 or 2 per 5cm x 5cm)
X: Remarkable wrinkles / dents are generated on the surface

Claims (3)

Nitrogen-containing unsaturated monomer having one or more hydrogen bonds selected from ethylenically unsaturated monomers having urethane bonds, ethylenically unsaturated monomers having imide bonds, and ethylenically unsaturated monomers having urea bonds (A ) And an unsaturated monomer (B) other than the unsaturated monomer (A), and a thickening agent that exhibits hydrophobic interaction with the acrylic resin composition. An aqueous coating composition comprising:
The thermosetting acrylic emulsion composition in which the thermosetting acrylic resin composition is dispersed in water, the thermosetting acrylic emulsion composition has a core-shell structure, and the mass ratio of the core to the shell is 1/9 to 9/1, and the amount of the nitrogen-containing unsaturated monomer (A) having hydrogen bonding in the shell part is 3 to 70% by mass of the total amount of the unsaturated monomers constituting the shell part,
The thickener is a urethane-urea thickener in which at least a part of the main chain is a hydrophobic urethane chain, or an amide-urea thickener in which at least a part of the main chain is a hydrophobic amide chain. A water-based coating composition characterized by being at least one selected . The nitrogen-containing unsaturated monomer (A) having hydrogen bonding in the thermosetting acrylic resin composition is N-methacryloyloxyethyl-N′-ethylurea and / or N-methacryloyloxyethyl-N′-butylurea The water-based coating composition according to claim 1. The mass ratio of the nitrogen-containing unsaturated monomer (A) and the unsaturated monomer (B) having hydrogen bonding in the thermosetting acrylic resin composition is 1/99 to 50/50, or The water-based coating composition according to 2.