JP5596263B2 - Water-based paint composition - Google Patents

Description

  The present invention relates to an aqueous coating composition suitable for forming a coating film excellent in stain resistance.

  In recent years, there has been a shift to water in the paint field. In general, water-based paints tend to be inferior in performance such as finish and water resistance compared to solvent-based paints due to hydrophilic groups and emulsifiers. However, with the recent market needs, it is desired to develop a water-based paint that forms a coating film that has good finish properties and water resistance, and also exhibits high functions such as stain resistance.

  In general, as a technique for imparting stain resistance, a technique for making a coating film water-repellent and a technique for making it hydrophilic are known. Either method can be selected according to the property or the like.

  As a method for making the surface of a coating film hydrophilic, a method of blending a modified condensate of organosilicate in a paint is known (see Patent Document 1). The modified organosilicate is considered to be hydrolyzed by moisture such as rain water in the coating film to form a silanol group and to make the coating surface layer hydrophilic. Although this method has the advantage that it can exhibit a self-cleaning action of washing away dirt components adhering to rainwater, etc., the modified organosilicate reacts with water, so the paint form must be made into two liquids, It takes time and labor to measure and mix immediately before use, and it takes time to make the surface of the coating film hydrophilic, and there is a problem that dirt adheres before the development of hydrophilicity.

  For example, Patent Document 2 discloses an aqueous solution containing a tertiary amino group- and carbonyl group-containing water-soluble acrylic resin, a carbonyl group-containing acrylic emulsion, and a hydrazide compound. A coating composition is disclosed.

  According to such a water-based coating composition, a coating film excellent in stain resistance can be formed, and a carbonyl group-containing acrylic which is a binder component by a hydrazide compound in which a tertiary amino group- and carbonyl group-containing water-soluble acrylic resin is a curing agent. Since it reacts with the emulsion, the stain resistance can be maintained for a long period of time, but it cannot be denied that the water resistance and weather resistance of the formed coating film are insufficient under the conditions of room temperature drying.

WO99 / 05228 JP 2000-119589 A

  An object of the present invention is to provide a water-based paint that exhibits stain resistance for a long period from an early stage after the formation of the paint film and is suitable for forming a paint film having excellent paint film properties such as water resistance and weather resistance. It is to provide a composition.

As a result of intensive studies on the above-mentioned problems, the present inventors have a specific relationship between the carboxyl group-containing polymerizable unsaturated monomer and the hydrophilic polymerizable unsaturated monomer in the aqueous coating composition containing the cross-linked resin composition. Thus, the present inventors have found that the above-described problems can be solved by including a carbonyl group-containing copolymer formed by solution polymerization in the presence of a specific organic solvent, and have reached the present invention.
That is, the present invention
1. A carbonyl group-containing copolymer (I) and a crosslinkable resin composition (II) are contained, and the copolymer (I) comprises a carbonyl group-containing polymerizable unsaturated monomer (a), a carboxyl group-containing polymerizable monomer. Obtained by solution polymerization of a monomer mixture containing a saturated monomer (b) and a hydrophilic polymerizable unsaturated monomer (c) other than the monomer (a) and the monomer (b) in the presence of a propylene glycol ether organic solvent. Total polymerization in which the copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) and the hydrophilic polymerizable unsaturated monomer (c) is used for the production of the copolymer (I). 30% by mass or more in the polymerizable unsaturated monomer, and the copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) is in the range of 0.1 to 70% by mass, and the hydrophilic polymerizable unsaturated monomer. -(C) is an alkyl (meth) acrylate having 1 to 2 carbon atoms in the ester part, a hydroxyl group-containing polymerizable unsaturated monomer, an alkoxy polyoxyalkylene group-containing polymerizable unsaturated monomer, an alkoxyalkyl (meth) acrylate, an amide A group-containing polymerizable unsaturated monomer, a morpholino group-containing polymerizable unsaturated monomer and at least one selected from the group consisting of a sulfonyl group-containing polymerizable unsaturated monomer,
And the crosslinkable resin composition (II) has a functional group capable of reacting with the functional group contained in the copolymer (I) or is self-crosslinking,
When the crosslinkable resin composition (II) has a functional group capable of reacting with the functional group contained in the copolymer (I), the crosslinkable resin composition (II) is a carbonyl group-containing emulsion polymer (IIa). And a hydrazine derivative, and a propylene glycol ether-based organic solvent is contained in the composition.
2.
2. The aqueous coating composition according to 1, wherein the hydrophilic polymerizable unsaturated monomer (c) is a polymerizable unsaturated monomer having a solubility in water of 25 ° C. of 0.5 or more.
3.
3. The aqueous coating composition according to item 1 or 2, wherein the carbonyl group-containing copolymer (I) has a weight average molecular weight in the range of 1000 to 50000,
4).
The aqueous coating composition according to any one of items 1 to 3, wherein the carbonyl group-containing emulsion polymer (IIa) has a core / shell structure,
5.
The glass transition temperature of the copolymer composed of the polymerizable unsaturated monomer constituting the core is in the range of −40 to 30 ° C., and the glass transition temperature of the copolymer composed of the polymerizable unsaturated monomer constituting the shell is 0. 5. The aqueous coating composition according to item 4, which is in the range of -80 ° C,
6).
The SP value of the carbonyl group-containing copolymer (I) is in the range of 9.0 to 13.0, and the SP value of the carbonyl group-containing emulsion polymer (IIa) is in the range of 8.0 to 10.0. Item 6. The water-based coating composition according to Item 4 or 5, wherein
7).
The crosslinkable resin composition (II) has a functional group capable of reacting with the functional group contained in the copolymer (I), and the copolymer (I) and the crosslinkable resin composition (II) When the resin component contained has a hydroxyl group, the crosslinkable resin composition (II) further includes one selected from polyisocyanate and melamine resin, and the resin component contained in the crosslinkable resin composition (II) is a carboxyl group. The water-based coating composition according to any one of 1 to 6, wherein the crosslinkable resin composition (II) further comprises one selected from a polyoxazoline compound, a polycarbodiimide compound and a metal compound,
8).
The crosslinked resin composition (II) contains a self-crosslinking resin, and the self-crosslinking resin has any one of unsaturated fatty acid group, alkoxysilyl group or maleimide group, Water-based paint composition according to item,
9.
Item 1 to Item 8 wherein the solid content of the carbonyl group-containing copolymer (I) is in the range of 0.01 to 30% by mass with respect to the resin component contained in the crosslinkable resin composition (II). The water-based paint composition according to any one of the above,
10.
10. A coating method comprising coating the surface to be coated with the aqueous coating composition according to any one of items 1 to 9.
About.

  According to the water-based coating composition of the present invention, a coating film excellent in coating physical properties such as water resistance and weather resistance can be exhibited over a long period from an early stage after the coating film is formed. Can be formed.

Carbonyl group-containing copolymer (I)
In the present invention, the carbonyl group-containing copolymer (I) comprises a carbonyl group-containing polymerizable unsaturated monomer (a), a carboxyl group-containing polymerizable unsaturated monomer (b) and a hydrophilic polymer in the presence of a hydrophilic organic solvent. It is a copolymer obtained by solution polymerization of a monomer mixture containing a polymerizable unsaturated monomer (c).

  In the present invention, the carbonyl group-containing polymerizable unsaturated monomer (a) exerts the stain resistance of the formed coating film for a long time, and when the crosslinked resin composition (II) has a carbonyl group, the resin composition ( II) is a monomer that is copolymerized to improve the compatibility with II and improve the final coating film properties such as finish and weather resistance, such as (meth) acrolein, formylstyrene, Examples thereof include vinyl alkyl ketones having 4 to 7 carbon atoms (for example, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone, etc.), acetoacetoxyethyl (meth) acrylate, acetoacetoxyallyl ester, diacetone (meth) acrylamide, and the like. Can be used alone or in combination of two or more, especially diacetone (meth) acrylic Mid is preferred.

  The above carboxyl group-containing polymerizable unsaturated monomer (b) is from the viewpoint of production stability of the aqueous coating composition of the present invention, and imparts hydrophilicity to the formed coating film, and improves finish and weather resistance. For example, (meth) acrylic acid, itaconic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and the like can be mentioned, and these can be used alone or in combination of two or more.

  In the present specification, the hydrophilic polymerizable unsaturated monomer (c) is a polymerizable unsaturated monomer other than the monomers (a) and (b), and is a coating film formed from the aqueous coating composition of the present invention. It is a generic term for the monomers introduced into the copolymer (I) in order to improve the hydrophilicity and to exhibit the stain resistance. Such hydrophilic polymerizable unsaturated monomers are soluble in water at 25 ° C. And a polymerizable unsaturated monomer having a molecular weight of 0.5 or more, particularly 1.0 or more.

  Specific examples of the hydrophilic polymerizable unsaturated monomer (c) include alkyl (meth) acrylates having 1 to 2 carbon atoms, alkoxyalkyl (meth) acrylates, hydroxyl group-containing polymerizable unsaturated monomers, and alkoxypolyoxyalkylene groups. Examples thereof include at least one selected from the group consisting of a containing polymerizable unsaturated monomer, an amide group-containing polymerizable unsaturated monomer, a morpholino group-containing polymerizable unsaturated monomer, and a sulfonyl group-containing polymerizable unsaturated monomer.

  Examples of the alkyl (meth) acrylate having 1 to 2 carbon atoms in the ester part include methyl (meth) acrylate and ethyl (meth) acrylate.

  Examples of the alkoxyalkyl (meth) acrylate include methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, ethoxyethyl (meth) acrylate, and the like.

  Examples of the hydroxyl group-containing polymerizable unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate. Hydroxyalkyl (meth) acrylates such as: (meth) acrylates having hydroxyl groups such as ε-caprolactone modified products of the above hydroxyalkyl (meth) acrylates; (meth) acrylates having a polyoxyethylene chain whose molecular ends are hydroxyl groups; Alcohol, trimethylolpropane monoallyl ether, ethylene glycol monoallyl ether, diethylene glycol monoallyl ether, triethylene glycol monoallyl ether, polyethylene glycol monoallyl ether Propylene glycol monoallyl ether, dipropylene glycol monoallyl ether, tripropylene glycol monoallyl ether, polypropylene glycol monoallyl ether, 1,2-butylene glycol monoallyl ether, 1,3-butylene glycol monoallyl ether, hexylene glycol mono And hydroxyl group-containing allyl compounds such as allyl ether, octylene glycol monoallyl ether, trimethylolpropane diallyl ether, glyceryl diallyl ether, and pentaerythritol triallyl ether.

  As said alkoxy polyoxyalkylene group containing polymerizable unsaturated monomer, the compound which can be represented, for example by a following formula can be mentioned.

(In the formula, R represents a hydrogen atom or a methyl group, R ¹ represents an alkyl group having 1 to 24 carbon atoms, p represents an integer of 2 or 3, and q represents an integer of 2 to 200).

  Examples of the amide group-containing polymerizable unsaturated monomer include (meth) acrylamide, N-methylol (meth) acrylamide, N, N-dimethylacrylimide, dimethylaminopropylacrylamide, and the like. These can be used in combination.

  Examples of the morpholino group-containing polymerizable unsaturated monomer include (meth) acryloylmorpholine.

  Examples of the sulfonyl group-containing polymerizable unsaturated monomer include 2-acrylamido-2-methylpropane sulfonic acid, allyl sulfonic acid, sodium styrene sulfonate, sulfoethyl methacrylate, and sodium and ammonium salts thereof. .

  In this invention, the said copolymer (I) may copolymerize other polymerizable unsaturated monomers (d) other than monomer (a), (b) and (c) as needed. Specific examples thereof include n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate, n-hexyl ( (Meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, “isostearyl acrylate” (Osaka Organic) Chemical)), cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, t-butylcyclohexyl (meth) acrylate, cyclododecyl (meth) acrylate, or other alkyl or cycloalkyl (meth) acrylate Relate; Condensed polycyclic alkyl group-containing (meth) acrylates such as isobornyl (meth) acrylate and adamantyl (meth) acrylate; Vinyl aromatic compounds such as styrene, α-methylstyrene and vinyltoluene; Vinyl ester compounds such as vinyl acetate; Mono Phosphoric acid group-containing polymerizable unsaturated monomers such as (acryloyloxyethyl) acid phosphate and mono (methacryloyloxyethyl) acid phosphate: fumaric acid ester compound; butyl vinyl ether, cyclohexyl vinyl ether, triethylene glycol divinyl ether, cyclohexanedimethanol divinyl ether , Hydroxybutyl vinyl ether, propenyl ether propylene carbonate, hydroxybutyl vinyl ether and isocyanate And vinyl ether compounds such as vinyl ether-terminated urethane oligomers can be used, and these can be used alone or in combination of two or more.

  In the present invention, the total copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) and the hydrophilic polymerizable unsaturated monomer (c) in the copolymer (I) is the production of the copolymer (I). 30% by mass or more of all polymerizable unsaturated monomers used in the above, wherein the copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) is in the range of 0.1 to 70% by mass. And

  When the total copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) and the hydrophilic polymerizable unsaturated monomer (c) is less than 30% by mass, the stain resistance and finish of the formed coating film are insufficient. Absent.

  When the copolymerization amount of the carboxyl group-containing polymerizable unsaturated monomer (b) is less than 0.1% by mass, the weather resistance and stain resistance of the formed coating film are deteriorated, while when it exceeds 70% by mass, the formed coating film is formed. This is not preferable because the stain resistance and weather resistance of the coating film are lowered, the water resistance is deteriorated, and bulges are easily generated in the coating film.

In the production of the copolymer (I), suitable copolymerization ratios of the monomers (a), (b), (c) and (d) are as follows:
The monomer (a) is 0.1 to 70% by mass, preferably 1 to 40% by mass,
The monomer (b) is 0.1 to 70% by mass, preferably 1 to 40% by mass,
The monomer (c) is 29.9 to 99.8% by weight, preferably 59 to 98% by weight,
When the monomer (d) is 0 to 69.9% by mass, preferably 0 to 39% by mass, the finish of the finally formed coating film is good, and the stain resistance, water resistance and weather resistance are good. It is suitable because it can exhibit the physical properties of the coating film in a well-balanced manner.

  As a polymerization initiator used for copolymerization of the above monomers, tert-butylperoxy 2-ethylhexanoate, benzoyl peroxide, octanoyl peroxide, lauroyl peroxide, stearoyl peroxide, cumene hydroperoxide, tert- Organic peroxides such as butyl hydroperoxide, 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-cyanobutanoic acid), dimethyl Luazobis (2-methylpropionate), azobis [2-methyl-N- (2-hydroxyethyl) -propionamide], azobis {2-methyl-N- [2- (1-hydroxybutyl)]-propionamide } And persulfates such as potassium persulfate, ammonium persulfate and sodium persulfate.

  As a suitable usage-amount of the said polymerization initiator, it is 0.001-15 mass% with respect to all the polymerizable unsaturated monomers used for manufacture of copolymer (I), Preferably 0.2-8 mass% It is desirable to be within the range.

  In applying the solution polymerization method, usable hydrophilic organic solvents include alcohol organic solvents such as methanol, ethanol, isopropanol, n-butanol and isobutanol; ether organic solvents such as dioxane and tetrahydrofuran; ethylene glycol monomethyl Ethylene glycol ether organic solvents such as ether, ethylene glycol monoethyl ether, ethylene glycol mono n-propyl ether, ethylene glycol monoisopropyl ether, ethylene glycol mono n-butyl ether, ethylene glycol monoisobutyl ether, ethylene glycol mono tert-butyl ether; Diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono n-propi Diethylene glycol ether organic solvents such as ether, diethylene glycol monoisopropyl ether, diethylene glycol mono n-butyl ether, diethylene glycol monoisobutyl ether, diethylene glycol mono tert-butyl ether; propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol mono n-propyl ether, Propylene glycol ether organic solvents such as propylene glycol monoisopropyl ether; dipropylene glycol ethers such as dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol mono n-propyl ether, dipropylene glycol monoisopropyl ether Machine solvent; 3- ester organic solvents such as methoxybutyl acetate and the like, which alone or may be used in combination of two or more. In particular, when a propylene glycol ether organic solvent is used, the water solubility or water dispersibility of the copolymer (I) is good, the storage stability of the aqueous coating composition containing it, the water resistance of the formed coating film, and the weather resistance Suitable from the point of sex.

  When the weight average molecular weight of the copolymer (I) is in the range of 1000 to 50000, particularly 1000 to 30000, the copolymer (I) is formed on the surface layer of the coating film formed from the aqueous coating composition of the present invention. Since the coating film surface is hydrophilized, it can exhibit stain resistance and is suitable.

  In this specification, the weight average molecular weight is a value obtained by converting the weight average molecular weight measured by gel permeation chromatograph (“HLC8120GPC” manufactured by Tosoh Corporation) based on the weight average molecular weight of polystyrene. Columns are “TSKgel G-4000H × L”, “TSKgel G-3000H × L”, “TSKgel G-2500H × L”, “TSKgel G-2000H × L” (both manufactured by Tosoh Corporation, trade names) ), Mobile phase: tetrahydrofuran, measurement temperature: 40 ° C., flow rate: 1 cc / min, detector: RI.

  According to the copolymer (I) obtained as described above, the coating film can be imparted with the property of spreading moisture attached to the coating film formed using the aqueous coating composition, It can exhibit anti-staining properties. In addition, if the surface of the coating has a tendency to spread water, the temperature of the coating can be lowered by the latent heat of vaporization during the drying process, such as by spraying the coating on which the coating is provided. Is possible.

Cross-linked resin composition (II)
In the present invention, the crosslinkable resin composition (II) is used as a coating film forming component of the aqueous coating composition of the present invention, and contains a resin other than the carbonyl group-containing copolymer (I). Thus, the resin composition is capable of forming a crosslinked coating film by the progress of the crosslinking reaction during the formation of the coating film.

  The resin component contained in the crosslinkable resin composition (II) preferably has a weight average molecular weight of more than 50000, and further has a weight average molecular weight of 100,000 or more. It is preferable from the viewpoint of physical properties of the coating such as water resistance, and it is desirable that it can be dissolved or dispersed in water.

  When the resin component contained in the cross-linked resin composition (II) is in the form of dispersed particles, it may be a single layer or a multilayer such as a core / shell type.

  In the present invention, the crosslinkable resin composition (II) has a functional group capable of reacting with a functional group contained in the copolymer (I) or is self-crosslinking.

  When the crosslinkable resin composition (II) has a functional group capable of reacting with the functional group contained in the copolymer (I), it is between the copolymer (I) and the crosslinkable resin composition (II). Specific examples of the crosslinking system are not particularly limited, but can be one-component crosslinking at room temperature, and are resistant to contamination, water resistance, and weather resistance of the coating film formed from the aqueous coating composition of the present invention. From the viewpoint of good coating film properties such as carbonyl group / hydrazide group crosslinking system.

  Preferable examples of such a crosslinked resin composition (II) include a composition containing a carbonyl group-containing emulsion polymer (IIa) and a hydrazine derivative (IIb). The aqueous coating composition of the present invention includes a carbonyl group A group-containing copolymer (I), a carbonyl group-containing emulsion polymer (IIa) and a hydrazine derivative (IIb), wherein the copolymer (I) is a carbonyl group-containing polymerizable unsaturated monomer (a), Copolymerizing a monomer mixture containing a carboxyl group-containing polymerizable unsaturated monomer (b) and a hydrophilic polymerizable unsaturated monomer (c) other than the monomer (a) and the monomer (b) in the presence of a hydrophilic organic solvent. Wherein the total copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) and the hydrophilic polymerizable unsaturated monomer (c) is the production of the copolymer (I) 30% by mass or more of all polymerizable unsaturated monomers used in the above, and the copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) is in the range of 0.1 to 70% by mass. It is desirable.

  In the present invention, the carbonyl group-containing emulsion polymer (IIa) is an emulsion polymer obtained by emulsion polymerization of a carbonyl group-containing polymerizable unsaturated monomer and another polymerizable unsaturated monomer in the presence of water and an emulsifier. is there.

  Specific examples of the carbonyl group-containing polymerizable unsaturated monomer used in the production of the emulsion polymer (II) are the same as the carbonyl group-containing polymerizable unsaturated monomer (a) in the copolymer (I), Particularly preferred is diacetone (meth) acrylamide.

  A preferable copolymerization ratio of the carbonyl group-containing polymerizable unsaturated monomer is 0.1 to 15% by mass, particularly 0.5 to 10%, in the total polymerizable unsaturated monomer used for the production of the emulsion polymer (IIa). % By mass.

  Examples of the other polymerizable unsaturated monomer for copolymerization with the carbonyl group-containing polymerizable unsaturated monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, and n-butyl (meth) ) Acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, etc. Linear or branched (meth) acrylate having a linear or branched hydrocarbon group; Alicyclic (meth) acrylate such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; Aralkyl such as benzyl (meth) acrylate (Meth) acrylates; alkoxyalkyl (meth) acrylates such as methoxymethyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxymethyl (meth) acrylate, ethoxyethyl (meth) acrylate; (meth) acrylamide, (meth) acrylonitrile Vinyl ester compounds such as vinyl acetate and vinyl propionate; vinyl aromatic compounds such as styrene and α-methylstyrene; allyl (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, tetra Ethylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,4-butanediol di (meth) acrylate Rate, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1, 1-trishydroxymethylethane di (meth) acrylate, 1,1,1-trishydroxymethylethane tri (meth) acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, triallyl isocyanurate, diallyl Polyvinyl compounds having at least two polymerizable unsaturated groups in one molecule such as terephthalate, divinylbenzene, etc .; 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxy Hydroxyalkyl (meth) acrylates such as propyl (meth) acrylate and hydroxybutyl (meth) acrylate, ε-caprolactone modified products of the above hydroxyalkyl (meth) acrylates; polyoxyethylene chain-containing (meth) acrylates whose molecular ends are hydroxyl groups Hydroxyl group-containing polymerizable unsaturated monomers such as hydroxyl group-containing allyl compounds such as allyl alcohol; carboxyl group-containing polymerizable unsaturated monomers such as (meth) acrylic acid, maleic acid, crotonic acid, itaconic acid, and β-carboxyethyl acrylate; Glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4-epoxycyclohexylethyl (meth) acrylate, 3,4-epoxy Epoxy group-containing polymerizable unsaturated monomers such as rohexylpropyl (meth) acrylate and allyl glycidyl ether; isocyanate group-containing polymerizable compounds such as isocyanate ethyl (meth) acrylate and m-isopropenyl-α, α-dimethylbenzyl isocyanate Unsaturated monomers; and the like. These may be used alone or in combination of two or more.

  The other polymerizable unsaturated monomer used in the above-mentioned emulsion polymer (IIa) is a carboxyl group-containing polymerizable unsaturated monomer, which is added to the total polymerizable unsaturated monomer used in the production of the emulsion polymer (II) in an amount of 0. The content of 01 to 10.0% by mass, particularly 0.01 to 3.0% by mass is preferable from the viewpoint of the production stability of the aqueous coating composition of the present invention and the finish of the formed coating film.

  As the emulsifier used in the emulsion polymerization of the emulsion polymer (IIa), conventionally known emulsifiers can be used. Examples of applicable emulsifiers include, for example, anionic emulsifiers, nonionic emulsifiers, amphoteric ones. An emulsifier etc. can be mentioned.

  Examples of the anionic emulsifier include diammonium dodecyl diphenyl ether disulfonate, sodium dodecyl diphenyl ether disulfonate, calcium dodecyl diphenyl ether disulfonate, alkyl diphenyl ether disulfonate such as sodium alkyl diphenyl ether disulfonate; sodium dodecyl benzene sulfonate, ammonium dodecyl benzene sulfonate, etc. Alkyl benzene sulfonates; alkyl sulfates such as sodium lauryl sulfate and ammonium lauryl sulfate; aliphatic carboxylates such as fatty acid sodiums and potassium oleate; sulfate salts containing polyoxyalkylene units (for example, polyoxyethylene alkyl ethers) Sodium sulfate, polyoxyethylene alkyl ether sulfate Polyoxyethylene alkyl ether sulfate salts such as nium; polyoxyethylene alkyl phenyl ether sulfate salts such as sodium polyoxyethylene alkyl phenyl ether sulfate and polyoxyethylene alkyl phenyl ether ammonium sulfate; polyoxyethylene polycyclic sodium phenyl ether sulfate; Polyoxyethylene polycyclic phenyl ether sulfate salts such as ammonium polyoxyethylene phenyl ether sulfate; etc.); naphthalene sulfonic acid formalin condensate sodium naphthalene sulfonic acid formalin condensate salt, etc .; sodium dialkylsulfosuccinate, monoalkyl succinate And alkyl succinate sulfonates such as disodium sulfonate and the like. These may be used alone or in combination of two or more. It is possible to use Te Align.

  Examples of nonionic emulsifiers include polyoxyalkylene unit-containing ether compounds (for example, polyoxyalkylene alkyl ether compounds such as polyoxyethylene lauryl ether, polyoxyethylene stearyl ether, polyoxyethylene tridecyl ether, polyoxyethylene oleyl ether). Polyoxyalkylene alkyl phenyl ether compounds such as polyoxyethylene octyl phenyl ether and polyoxyethylene nonyl phenyl ether; polyoxyalkylene polycyclic phenyl ether compounds such as polyoxyethylene polycyclic phenyl ether; etc.); polyoxyethylene monolaur Polyoxyalkylene alkyl ester compounds such as rate, polyoxyethylene monostearate, polyoxyethylene monooleate; Polyoxyalkylene alkylamine compounds such as reoxyethylene alkylamine; sorbitan compounds such as sorbitan monolaurate, sorbitan monostearate, sorbitan trioleate, polyoxyethylene sorbitan monolaurate, polyoxyethylene sorbitan monooleate; Can be used alone or in combination of two or more.

  Examples of amphoteric surfactants include dimethylalkyl betaines, dimethylalkyl lauryl betaines, and alkyl glycines.

  As the emulsifier, a reactive emulsifier containing a polymerizable unsaturated group and an anionic group or a nonionic group in the molecule can also be used.

  As the usage-amount of the said emulsifier, it shall be 0.5-6 mass% with respect to all the polymerizable unsaturated monomers used for manufacture of emulsion polymer (IIa), Preferably it shall be in the range of 1-4 mass%. Can do.

  On the other hand, the polymerization initiator can be appropriately selected from those listed in the description of the copolymer (I).

  As a suitable usage-amount of the said polymerization initiator, it is the range of 0.001-5 mass% with respect to all the polymerizable unsaturated monomers used for manufacture of an emulsion polymer (IIa), and the range of 0.2-3 mass%. It is desirable to be within.

  In the present invention, the carbonyl group-containing emulsion polymer (IIa) preferably has a core / shell structure.

  The carbonyl group-containing emulsion polymer (IIa) having a core / shell structure is generally obtained by emulsion polymerization of a polymerizable unsaturated monomer containing a carbonyl group-containing polymerizable unsaturated monomer in two stages in the presence of water and an emulsifier. Manufactured by. That is, after the polymerizable unsaturated monomer mixture for constituting the core is subjected to emulsion polymerization in the presence of water and an emulsifier, a resin aqueous dispersion is produced, and then polymerization for constituting the shell in the resin dispersion. The unsaturated unsaturated monomer mixture is dropped and emulsion polymerization is performed.

  In the present invention, the glass transition temperature of the copolymer composed of the polymerizable unsaturated monomer constituting the core is in the range of −40 to 30 ° C., particularly −20 to 30 ° C. The hardness of the coating film formed from the aqueous coating composition of the present invention is that the glass transition temperature of the copolymer comprising a saturated monomer is in the range of 0 to 80 ° C., particularly 10 to 80 ° C., It is good because it is excellent in stain resistance.

  It is more desirable that the glass transition temperature of the copolymer composed of the polymerizable unsaturated monomer constituting the shell is higher than the glass transition temperature of the copolymer composed of the polymerizable unsaturated monomer constituting the core.

In this specification, the glass transition temperature (° C.) of the copolymer can be calculated by the following formula.
1 / Tg (° K) = (W ₁ / T ₁ ) + (W ₂ / T ₂ ) +
Tg (° C.) = Tg (° K) -273
In each formula, W ₁ , W ₂ ,... Represent the respective mass percentages of the monomers used in the copolymerization, and T ₁ , T ₂ ,... Represent the Tg (° K) of the monomer homopolymer, respectively. . T ₁ , T ₂ ,... Are values according to Polymer Hand Book (Second Edition, edited by J. Brandup / EHImmergut) pages III-139 to 179.

  In the carbonyl group-containing emulsion polymer having the core-shell structure, the mass ratio of the polymerizable unsaturated monomer constituting the core and the polymerizable unsaturated monomer constituting the shell is 90/10 to 10 in terms of the core / shell mass ratio. / 90, particularly within the range of 80/20 to 20/80, is preferable from the viewpoint of stain resistance of the coating film formed from the aqueous coating composition of the present invention.

  In addition, since the coating film formed from the aqueous coating composition of the present invention can achieve both coating film properties such as stain resistance, water resistance, and weather resistance, and good finish can be obtained, the carbonyl group-containing copolymer can be obtained. The SP value of the polymer (I) is in the range of 9.0 to 13.0, particularly in the range of 10.0 to 12.5, and the SP value of the carbonyl group-containing emulsion polymer (IIa) is 8.0. It is desirable to be in the range of ˜10.0, particularly 8.2 to 9.5.

In this specification, the SP value of a copolymer or an emulsion polymer is calculated by the following formula using the SP value of a homopolymer of each polymerizable unsaturated monomer.
SP value = SP ₁ × W ₁ + SP ₂ × W ₂ +... + SP _n × W _n
In each formula, W ₁ , W ₂ ,... Are the respective mass percentages of the monomers used in the copolymerization, SP ₁ , SP ₂ ,... SP _n are the SP of the homopolymer of each polymerizable unsaturated monomer Represents the value. SP ₁ , SP ₂ ,... SP _n are J. Paint Tecnology, vol. 42, 176 (1970).

  In the present invention, when the crosslinkable resin composition (II) has a functional group capable of reacting with the functional group contained in the copolymer (I), the copolymer (I) and the crosslinkable resin composition (II) At least one selected from a hydroxyl group / isocyanate group crosslinking system, a hydroxyl group / melamine crosslinking system, a carboxyl group / oxazoline group crosslinking system, a carboxyl group / carbodiimide group crosslinking system, and a carboxyl group / metal ion crosslinking system. It may be a seed.

  The crosslinkable functional group capable of forming the above crosslinking system may be present in either the copolymer (I) or the crosslinkable resin composition (II), but the copolymer (I) at the time of coating film formation. The resin component contained in the copolymer (I) and the crosslinkable resin composition (II) has a hydroxyl group and / or a carboxyl group from the viewpoint of surface migration, hydrophilic expression, stain resistance, etc. It is desirable that the resin composition (II) contains a crosslinking agent having a functional group capable of reacting with a hydroxyl group or a carboxyl group.

  Since the copolymer (I) and the crosslinkable resin composition (II) have the above-described configuration, the copolymer (I) is crosslinked with the crosslinkable resin composition (II) to form a cross-linked coating film. It can be taken in, and the hydrophilicity of the coating film can be exhibited over a long period of time.

  In the present invention, the resin having a hydroxyl group and / or a carboxyl group as the resin component contained in the crosslinkable resin composition (II) is not particularly limited, and specifically, for example, an acrylic resin Resin, polyolefin resin, silicon resin, polyurethane resin, epoxy resin, phenol resin, polyester resin, alkyd resin, polycarbonate resin, etc., and these can be used alone or in combination of two or more. Can be used. These resins may be modified like, for example, urethane-modified acrylic resins, or may be graft-polymerized.

  In the present invention, the resin component is preferably an acrylic resin from the viewpoint of compatibility with the copolymer (I) and weather resistance.

  As such an acrylic resin having a hydroxyl group and / or a carboxyl group, a hydroxyl group-containing polymerizable unsaturated monomer and / or a carboxyl group-containing polymerizable unsaturated monomer and, if necessary, other polymerizable unsaturated monomers may be copolymerized. Can be obtained.

  Examples of the hydroxyl group-containing polymerizable unsaturated monomer include hydroxyalkyl (meth) such as 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, and hydroxybutyl (meth) acrylate. Acrylates, ε-caprolactone modified products of the above hydroxyalkyl (meth) acrylates; polyoxyethylene chain-containing (meth) acrylates whose molecular ends are hydroxyl groups; hydroxyl-containing allyl compounds such as allyl alcohol, and the like. Or in combination of two or more.

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

  Other polymerizable unsaturated monomers include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, and pentyl. Linear or branched (meta) having a linear or branched hydrocarbon group such as (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, etc. ) Acrylate; alicyclic (meth) acrylate such as cyclohexyl (meth) acrylate and isobornyl (meth) acrylate; aralkyl (meth) acrylate such as benzyl (meth) acrylate; 2-methoxyethyl (meth) acrylate, 2- Alkoxyalkyl (meth) acrylates such as toxiethyl (meth) acrylate; perfluoroalkyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate; (meth) acrylamide, (meth) acrylonitrile; vinyl acetate, vinyl propionate, etc. Vinyl aromatic compounds such as styrene and α-methylstyrene; 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-hexanediol di (meth) acrylate, pentaerythritol di (meth) acrylate, pentaerythritol tetra (meth) acrylate, glycerol di (meth) acrylate, 1,1,1-trishydroxymethylethanedi (meta ) In one molecule such as acrylate, 1,1,1-trishydroxymethylethane tri (meth) acrylate, 1,1,1-trishydroxymethylpropane tri (meth) acrylate, triallyl isocyanurate, diallyl terephthalate, divinylbenzene A poly vinyl compound having at least two polymerizable unsaturated groups, glycidyl (meth) acrylate, β-methylglycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate, 3,4- Epoxy group-containing polymerizable unsaturated monomers such as poxycyclohexylethyl (meth) acrylate, 3,4-epoxycyclohexylpropyl (meth) acrylate, and allyl glycidyl ether; and the like. These may be used alone or in combination of two or more. Can be used.

  As a method for polymerizing the monomer, it can be carried out by a conventionally known method, for example, it can be produced by a solution polymerization method, a bulk polymerization method, an emulsion polymerization method or the like. This is desirable because the content of the organic solvent in the resulting composition can be reduced.

  In addition, a polymerization method or the like in which a mixture containing a polymerizable unsaturated monomer is finely dispersed in an aqueous medium so that the average particle diameter is 500 nm or less and the resulting monomer emulsion is polymerized can also be applied.

  In this specification, the average particle size of the monomer emulsion and the emulsion after polymerization is obtained by diluting the sample with deionized water, and then “SALD-3100” (trade name, manufactured by Shimadzu Corporation, laser diffraction particle size distribution analyzer. ) And the value when measured at room temperature (about 20 ° C.).

  Moreover, as an aqueous medium used at the time of superposition | polymerization, the water-organic solvent mixed solution etc. which mix water and organic solvents, such as a water-soluble organic solvent, can be mentioned to this.

  When emulsifiers are used in the polymerization of the above monomers, conventionally known emulsifiers can be used. Examples of applicable emulsifiers include anionic emulsifiers, nonionic emulsifiers, and zwitterionic emulsifiers. it can.

  Specific examples of the anionic emulsifier, the nonionic emulsifier and the amphoteric emulsifier are as described above, and a reactive emulsifier containing a polymerizable unsaturated group and an anionic group or a nonionic group in the molecule can also be used. It is.

  When the emulsifier is used, the amount used is 0.5 to 6% by mass, preferably 1 to 4% by mass, based on the total polymerizable unsaturated monomer used in the production of the acrylic resin. can do.

Hydrazine derivatives (IIa)
The aqueous coating composition of the present invention preferably further contains a hydrazine derivative (IIa). Thereby, the stain resistance of the formed coating film can be maintained over a long period of time, and the coating film properties such as water resistance and weather resistance can be further improved. In particular, when the crosslinkable resin composition (II) contains a carbonyl group-containing emulsion polymer (IIa), it is desirable to further contain a hydrazine derivative (IIa).

  Examples of the hydrazine derivative (IIa) include hydrazine, hydrazine hydrate; dihydrazides of saturated aliphatic dicarboxylic acids such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide; Monoolefinic unsaturated dicarboxylic acid dihydrazide such as maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide; phthalic acid, terephthalic acid or isophthalic acid dihydrazide; pyromellitic acid dihydrazide, trihydrazide or tetrahydrazide; nitrilotriacetic acid trihydrazide , Citric acid trihydrazide, 1,2,4-benzenetricarboxylic acid trihydrazide; ethylenediaminetetraacetic acid tetrahydrazide, 1,4,5,8-na Toeic acid tetrahydrazide; polyhydrazide obtained by reacting a low polymer having a carboxylic acid lower alkyl ester group with hydrazine or hydrazine hydrate (hydrazine hydride); carbonic acid dihydrazide, bissemicarbazide; hexamethylene diisocyanate, isophorone diisocyanate, etc. A polyfunctional semicarbazide obtained by excessively reacting a diisocyanate and a polyisocyanate compound derived therefrom with N, N-substituted hydrazine such as N, N-dimethylhydrazine or the hydrazide exemplified above; the polyisocyanate compound and polyether polyols And an aqueous multi-component obtained by excessively reacting the above-exemplified dihydrazide with an isocyanate group in a reaction product with an active hydrogen compound containing a hydrophilic group such as polyethylene glycol monoalkyl ethers An active semicarbazide; a mixture of the polyfunctional semicarbazide and an aqueous polyfunctional semicarbazide; bisacetyldihydrazone and the like can be suitably used. The compounds described above can be used alone or in combination of two or more.

  The blending amount of the hydrazine derivative (IIa) is 0.01 to 2.0 mol, preferably 0, based on 1 mol of the carbonyl group contained in the aqueous coating composition, based on the hydrazide group contained in the hydrazine derivative (IIa). It is suitable from the standpoint of cracking resistance of the formed coating film that the ratio is in the range of 1 to 1.5 mol.

  Further, when the resin component contained in the copolymer (I) and / or the crosslinkable resin composition (II) has a hydroxyl group, a polyisocyanate or a melamine resin is used as a crosslinking agent to be a reaction partner of the hydroxyl group. May be.

  Examples of the polyisocyanate compound include aliphatic diisocyanates such as tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, trimethylhexamethylene diisocyanate, and lysine diisocyanate; fats such as 4,4′-methylenebis (cyclohexyl isocyanate) and isophorone diisocyanate. Cyclic diisocyanates; aromatic diisocyanates such as xylylene diisocyanate, tolylene diisocyanate, diphenylmethane diisocyanate, polyphenylmethane diisocyanate; similar compounds such as isocyanurates and burettes of these diisocyanates. It can be used in combination of more than one species.

  In addition, the polyisocyanate compound may be a water-dispersible polyisocyanate obtained by reacting a polyisocyanate compound containing at least two isocyanate groups in one molecule with a nonionic emulsifier. As the nonionic emulsifier capable of reacting with the polyisocyanate compound, the same nonionic emulsifiers as described above can be used, and in particular, an active hydrogen group that reacts with an isocyanate group and an oxyalkylene unit. Those having an oxyethylene unit are preferred.

  The water-dispersible polyisocyanate may be modified by reacting with a silane coupling agent having an active hydrogen group at one end and an alkoxysilyl group at the other end, if necessary. Examples of the silane coupling agent include N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethyldimethoxysilane, and γ-aminopropyltriethoxy. Examples include silane, N-phenyl-γ-aminopropyltrimethoxysilane, and γ-mercaptopropyltrimethoxysilane.

  Commercially available products of such water-dispersible polyisocyanates include, for example, “Baihijoule 3100”, “VPLS2319” (trade name, manufactured by Bayer, Inc.), “Staffroid WD-220” (trade name, manufactured by Mitsui Chemicals Polyurethanes, Inc.) And the like.

  When the polyisocyanate compound is blended, the water-based coating composition of the present invention may be blended immediately before use to form a two-pack type. Moreover, the compounding quantity is 0.05-2 mol normally in the amount of the isocyanate group in a polyisocyanate compound with respect to 1 mol of hydroxyl groups contained in the water-based coating composition of this invention, Preferably it is 0.1-1 mol. It is desirable to adjust so that it may be in the range.

  Examples of the melamine resin include a resin having an alkyl ether group and / or an imino group in the molecule, which is obtained by reacting melamine, formaldehyde and water and / or alcohol as necessary. Is, for example, methylol melamine such as dimethylol melamine, trimethylol melamine, tetramethylol melamine, pentamethylol melamine, hexamethylol melamine; alkyl ether compound of the methylol melamine; condensate of methylol melamine or its alkyl ether compound, etc. . Examples of the alkyl group in the methyl ether melamine alkyl ether include alkyl groups having 1 to 8 carbon atoms such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, and 2-ethylhexyl groups.

  When the melamine resin is blended, the blending amount is usually 0.05 to 2 mol of alkyl ether group and / or imino group in the melamine resin with respect to 1 mol of hydroxyl group contained in the aqueous coating composition of the present invention. It is desirable that the content be adjusted to be in the range of 0.1 to 1 mol.

  In addition, when the resin component contained in the copolymer (I) and / or the crosslinkable resin composition (II) has a carboxyl group, the compound that can serve as a crosslinker that reacts with the carboxyl group includes polyoxazoline. A compound, a polycarbodiimide compound, a metal compound, etc. can be mentioned.

  Examples of the polyoxazoline compound include compounds having two or more oxazoline groups in the molecule, 2,2′-p-phenylene-bis- (1,3-oxazoline), 2,2′-tetramethylene- Low molecular weight poly (1,3-oxazoline) compounds such as bis- (1,3-oxazoline), 2,2′-octamethylene-bis- (2-oxazoline); A homopolymer of a 1,3-oxazoline group-containing vinyl monomer such as oxazoline or 2-isopropenyl-1,3-oxazoline, or various vinyl monomers copolymerizable therewith is copolymerized. Examples thereof include a vinyl polymer containing a 1,3-oxazoline group.

  Commercially available products include “Epocross K-1000”, “Epocross K-1020E”, “Epocross K-1030E”, “Epocross K-2010E”, “Epocross K-2020E”, “Epocross K-2030E”, “Epocross WS” -500 "(trade name, manufactured by Nippon Shokubai Chemical Industry Co., Ltd.).

  The compounding amount of the polyoxazoline compound is usually 0.05 to 2 mol, preferably 0.1, based on 1 mol of the carboxyl group contained in the aqueous coating composition of the present invention. It is desirable to adjust so that it may be in the range of ˜1 mol.

  Examples of the polycarbodiimide compound include compounds having two or more carbodiimide groups in the molecule, and are not particularly limited, but are preferably water-soluble or water-dispersible, and have a carbodiimide equivalent of 100 to 800. It is desirable that the compound be in the range of 200 to 600.

  Specific examples thereof include commercially available products such as “Carbodilite V-02”, “Carbodilite V-04”, “Carbodilite V-06” (trade name, manufactured by Nisshinbo Co., Ltd.). These can be used alone or in a mixture of two or more.

  The compounding amount of the polycarbodiimide compound is usually 0.05 to 2 mol, preferably 0.1 to 1 mol of the carbodiimide group in the carbodiimide compound with respect to 1 mol of the carboxyl group contained in the aqueous coating composition of the present invention. It is desirable to adjust so that it may be in the range of mole.

The metal compound is a metal compound capable of generating a metal ion capable of metal crosslinking with a carboxyl group in an aqueous medium, and has a bivalent or higher valence such as Ba, Fe, Ca, Mg, Cu, Al, Zn and Mn. metal can include compounds made based on, and specific examples _{thereof, MgCO 3, CaCO 3, FeCO} 3, BaCO 3, ZnCO 3, CuCO 3 and _Al 2 _{(CO 3)} 3 metal carbonates such as Compounds; metal hydroxides such as Mg (OH) ₂ , Ca (OH) ₂ , Zn (OH) ₂ , Fe (OH) ₂ , Fe (OH) ₃ , Ba (OH) ₂ , and Al (OH) ₃ A metal oxide such as ZnO, MgO, Al ₂ O ₃ and CaO; and an organometallic complex such as acetylacetone zinc. These can be used alone or in combination of two or more.

  The compounding amount of the metal compound is such that the amount of metal ions in the metal compound is usually 0.01 to 2 mol, preferably 0.05 to 1 with respect to 1 mol of the carboxyl group contained in the aqueous coating composition of the present invention. It is desirable to adjust so that it may be in the range of mole.

  In the present invention, the crosslinkable resin composition (II) may be a selfcrosslinkable type containing a selfcrosslinkable resin. Thereby, there exists an effect which improves water resistance, without reducing the hydrophilicity of the coating film formed using the water-based coating composition of this invention. Specific examples of the self-crosslinking resin include a resin having an unsaturated fatty acid group, an alkoxysilyl group, or a maleimide group.

  The type of resin as the self-crosslinking resin is not particularly limited. Specifically, for example, acrylic resin, polyolefin resin, silicon resin, polyurethane resin, epoxy resin, phenol resin, polyester -Based resins, alkyd-based resins, polycarbonate-based resins, and the like, and these can be used alone or in combination of two or more. These resins may be modified like, for example, urethane-modified acrylic resins, or may be graft-polymerized.

  In the present invention, the self-crosslinking resin is preferably a self-crosslinking acrylic resin from the viewpoint of compatibility with the copolymer (I) and weather resistance.

  Examples of such self-crosslinking acrylic resins include unsaturated fatty acid group-containing polymerizable unsaturated monomers, alkoxysilyl group-containing polymerizable unsaturated monomers, or maleimide group-containing polymerizable unsaturated monomers, and if necessary, these monomers The resin obtained by copolymerizing the other polymerizable unsaturated monomer which can be copolymerized can be mentioned.

  Examples of the unsaturated fatty acid group-containing polymerizable unsaturated monomer include an epoxy group-containing polymerizable unsaturated monomer or a reaction product of a hydroxyl group-containing polymerizable unsaturated monomer and an unsaturated fatty acid, dicyclopentenyloxyethyl (meth) acrylate, di Examples thereof include cyclopentenyloxypropyl (meth) acrylate and dicyclopentenyl (meth) acrylate, and these can be used alone or in combination of two or more.

  Examples of the unsaturated fatty acid include fish oil fatty acid, dehydrated castor oil fatty acid, safflower oil fatty acid, linseed oil fatty acid, soybean oil fatty acid, sesame oil fatty acid, poppy oil fatty acid, eno oil fatty acid, hemp oil fatty acid, grape kernel oil fatty acid, Examples include corn oil fatty acid, tall oil fatty acid, sunflower oil fatty acid, cottonseed oil fatty acid, walnut oil fatty acid, rubber seed oil fatty acid, and hydienoic acid fatty acid.

  Examples of the polymerizable unsaturated monomer containing an alkoxysilyl group include vinyltrimethoxysilane, vinyltriethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriethoxysilane, and the like. It can be used alone or in combination of two or more.

  The maleimide group in the maleimide group-containing polymerizable unsaturated monomer has a property of dimerization by light irradiation, so that a self-crosslinking reaction can proceed at normal temperature under irradiation of sunlight.

  As the maleimide group-containing polymerizable unsaturated monomer, a compound represented by the following formula is preferably used.

In each formula, R ² and R ³ independently represent a hydrogen atom or a methyl group. R ⁴ and R ⁵ independently represent an alkyl group having 4 or less carbon atoms. n shows the integer of 1-6.

  As a method for polymerizing the monomer, it can be carried out by a conventionally known method, for example, it can be produced by a solution polymerization method, a bulk polymerization method, an emulsion polymerization method or the like. This is desirable because the content of the organic solvent in the resulting composition can be reduced. In addition, a polymerization method or the like in which a mixture containing a polymerizable unsaturated monomer is finely dispersed in an aqueous medium so as to have an average particle diameter of 500 nm or less as required, and the resulting monomer emulsion is polymerized is also applicable. .

  Examples of the emulsifier that can be used in the production of the self-crosslinking resin include the compounds exemplified above.

  The aqueous coating composition of the present invention contains the copolymer (I) and the crosslinkable resin composition (II), and the solid content of the copolymer (I) is a crosslinkable resin composition ( II) The resin component contained in the range of 0.01 to 30% by mass, particularly 0.1 to 15% by mass, has a stain resistance, water resistance and weather resistance of the formed coating film. It is desirable from the viewpoint of exerting a good balance.

  Moreover, the said water-based coating composition can contain the curing catalyst etc. for the bridge | crosslinking of crosslinkable resin composition (II) to advance as needed.

  Since the aqueous coating composition of the present invention contains a carboxyl group, it is suitable to contain a neutralizing agent from the viewpoints of production stability and finish of the formed coating film. The neutralizing agent that can be used in this case may be a basic compound that can neutralize acidic groups. Specific examples thereof include, for example, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, dimethylamino. Examples include amines such as ethanol and 2-methyl-2-amino-1-propanol; ammonia; alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and the like. These can be used in combination.

  These neutralizing agents can be blended at any stage of production of the aqueous coating composition. The blending amount thereof is such that the pH of the aqueous coating composition is 7.5 to 11.0, particularly 8.0. It is desirable to use in such an amount that it becomes 10.0.

  When the water-based coating composition of the present invention contains a pigment, a conventionally known pigment used in the field of paint can be used as the pigment to be used. Specific examples include coloring pigments such as titanium oxide, carbon black, and bengara; barita powder, precipitated barium sulfate, barium carbonate, calcium carbonate, gypsum, clay, silica, white carbon, diatomaceous earth, talc, magnesium carbonate, alumina white And extender pigments such as gloss white, etc., and these can be used alone or in combination of two or more.

  In the present invention, the amount of the pigment used can be appropriately adjusted according to the type of pigment and the desired finish, but generally 10 to 200 parts by mass, especially 100 parts by mass of resin solids contained in the aqueous coating composition. Adjustment within the range of 20 to 150 parts by mass is desirable from the viewpoints of the finish of the formed coating film and the coating workability.

  The aqueous coating composition of the present invention comprises a hydrophilizing agent selected from the group consisting of hydrolyzable silyl group-containing organosilane compounds, colloidal silica, and photocatalytically active titanium oxide; thickeners, surfactants, dispersants, quenchers. Additives for paints such as foaming agents, antiseptics, antifungal agents, antifreezing agents, ultraviolet absorbers, light stabilizers, film-forming aids, and the like can be blended as necessary.

  The water-based coating composition of the present invention can be applied to a new substrate surface or an old coating surface, and the substrate is not particularly limited, and examples thereof include concrete, mortar, slate plate, PC Inorganic base materials such as plates, ALC plates, cement calcium silicate plates, concrete blocks, wood, stones, etc .; organic base materials such as plastics; metals such as iron and aluminum, etc. Examples of the coating film include acrylic resin, acrylic urethane resin, polyurethane resin, fluororesin, silicon acrylic resin, vinyl acetate resin, epoxy resin, and alkyd resin provided on the material. An aqueous or solvent-type undercoat material may be applied to these coated surfaces. If necessary, after applying the undercoat material, the aqueous coating composition can be applied as a topcoat material.

  The aqueous coating composition of the present invention can be applied by a conventionally known method, and as a drying method, a coating film having excellent physical properties such as stain resistance and weather resistance and finish properties can be formed even at room temperature drying. Although it is possible, heat drying or forced drying may be performed depending on the composition, such as when using melamine, or depending on the coating environment.

  Hereinafter, the present invention will be described in more detail with reference to examples. Here, “parts” and “%” mean “parts by mass” and “% by mass”, respectively.

Manufacture example 1 of acrylic resin solution
A four-necked flask equipped with a stirrer, thermometer, condenser, and nitrogen gas inlet was charged with 70 parts of propylene glycol monomethyl ether, heated to 110 ° C. with stirring, and then the temperature of the liquid in the four-necked flask Was maintained at 110 ° C., and a mixture of a monomer, a solvent and a polymerization initiator shown in Table 1 below was dropped at a constant rate using a dropping pump over 3 hours. An initiator solution in which 0.5 part of an additional polymerization initiator (tert-butylperoxy 2-ethylhexanoate) was dissolved in 10 parts of propylene glycol monomethyl ether was maintained at 110 ° C. for 1.5 hours after completion of the dropping. Was added dropwise at a constant rate over 1.5 hours, and further kept at 110 ° C. for 3 hours, and stirring was continued to obtain an acrylic resin solution (A-1). The weight average molecular weight of the obtained resin was about 4,500. The solid content was 43%, and the acid value was 78 mgKOH / g.

Production Examples 2-15
Except for the composition shown in Table 1, the same procedure as in Production Example 1 was carried out, and each acrylic resin solution (A-2) to (

A-15) was obtained. The property values of the obtained resin solution are also shown in Table 1.

“Blemmer PME-400”: trade name, manufactured by NOF Corporation, methoxypolyoxyethylene group-containing methacrylate having an average number of oxyethylene groups of 9.

Production of carbonyl group-containing acrylic resin emulsion Production Example 16
Add 312 parts of deionized water and 2.3 parts of “Newcol 707SF” (manufactured by Nippon Emulsifier Co., Ltd., an anionic emulsifier having a polyoxyethylene chain, solid content of 30%) to a 2 liter four-necked flask. Maintained at 80 ° C. Immediately before the pre-emulsion having the following composition was dropped into the four-necked flask, 0.7 part of ammonium persulfate was added, and the pre-emulsion was dropped over 3 hours.
Deionized water 338 parts diacetone acrylamide 32 parts acrylic acid 3.2 parts styrene 97 parts methyl methacrylate 260 parts 2-ethylhexyl acrylate 100 parts n-butyl acrylate 150 parts "Newcol 707SF" 62 parts ammonium persulfate 1.2 parts From 30 minutes, a solution in which 0.7 parts of ammonium persulfate was dissolved in 7 parts of deionized water was added dropwise for 30 minutes, maintained at 80 ° C. for 2 hours, and then cooled to about 40-60 ° C. The pH was adjusted to 8-9 to obtain a carbonyl group-containing acrylic resin emulsion (B-1) having a solid content of 51.2%. The SP value of the resin of this emulsion was 9.0.

Production of carbonyl group-containing core-shell acrylic resin emulsion Production Example 17
Add 28.5 parts deionized water, Newcol 707SF (manufactured by Nippon Emulsifier Co., Ltd., anionic emulsifier having a polyoxyethylene chain, solid content 30%) to a 2 liter four-necked flask, and after purging with nitrogen, Maintained at 85 ° C. 3% of pre-emulsion (for core) formed by emulsifying the following composition in this and 25% of 10.5 parts of ammonium persulfate aqueous solution in which 0.5 part of ammonium persulfate was dissolved in 10 parts of deionized water After 20 minutes from the addition, 67% of the pre-emulsion (for core) and 50% of the ammonium persulfate aqueous solution were added dropwise over 2 hours.
Pre-emulsion composition (for core)
Deionized water 36.8 parts Styrene 15 parts Methyl methacrylate 43.8 parts n-Butyl acrylate 24 parts 2-Ethylhexyl acrylate 15 parts Hydroxyethyl acrylate 2 parts Acrylic acid 0.2 part "Newcol 707SF" 6.6 parts After completion of dropping After maintaining this at 85 ° C. for 2 hours, 30% of a pre-emulsion (for shell) formed by emulsifying the following composition and 25% of the aqueous ammonium persulfate solution were added dropwise over 2 hours.
Pre-emulsion composition (for shell)
Deionized water 36.8 parts styrene 15 parts methyl methacrylate 58.8 parts n-butyl acrylate 14 parts 2-ethylhexyl acrylate 5 parts diacetone acrylamide 5 parts hydroxyethyl acrylate 2 parts acrylic acid 0.2 parts “Newcol 707SF” 6.6 parts After the completion of dropping, the temperature was further maintained at 85 ° C. for 2 hours, and then the temperature was lowered to 40-60 ° C. Subsequently, the pH was adjusted to 8 to 9 with aqueous ammonia to obtain a carbonyl group-containing core-shell acrylic resin emulsion (B-2) having a solid content of 55%. The Tg of the core of this emulsion was 18 ° C., the Tg of the shell was 54 ° C., and the SP value of the resin was 9.1.

Production and production example 18 of fatty acid-modified acrylic resin emulsion
The following components are put in a container, stirred at 2000 rpm with a disper for 15 minutes to produce a preliminary emulsion, and then the preliminary emulsion is subjected to a high pressure treatment at 100 MPa in a high pressure emulsifier that collides the fluids by applying high pressure energy. As a result, a monomer emulsion having an average particle size of the dispersed particles of 190 nm was obtained.
Monomer emulsion composition Fatty acid-modified monomer (*) 30.15 parts Styrene 12 parts i-butyl methacrylate 7.85 parts 2-ethylhexyl acrylate 15 parts methacrylic acid 2 parts cyclohexyl methacrylate 30 parts diacetone acrylamide 3 parts "Newcol 707SF 10 parts deionized water 85 parts The above monomer emulsion 546 parts was transferred to a flask and diluted with 95 parts deionized water. While stirring, the temperature was raised to 85 ° C., an aqueous initiator solution in which 1 part of ammonium persulfate was dissolved in 64.7 parts of deionized water was added to the flask, and the mixture was stirred for 3 hours while maintaining the temperature. Further, an initiator aqueous solution in which 0.25 parts of ammonium persulfate was dissolved in 16.2 parts of deionized water was added to the flask, stirred for 3 hours while maintaining the temperature, and then cooled to 40 ° C. The pH was adjusted to 8.0 with dimethylaminoethanol to obtain a fatty acid-modified acrylic resin emulsion (B-3) having a solid content of 40% and an average particle size of 185 nm.
(*) Fatty acid-modified monomer 280 parts of safflower oil fatty acid and 142 parts of glycidyl methacrylate were placed in a reaction vessel and reacted at a reaction temperature of 140 ° C. for 5 hours with stirring to produce a fatty acid-modified monomer.

Manufacture example 19 of maleimide group-containing acrylic resin emulsion
In a flask, 10 parts of a maleimide group-containing monomer represented by the following formula, 50 parts of n-butyl methacrylate, 25 parts of methyl methacrylate, 14 parts of n-butyl acrylate and 1 part of methacrylic acid are mixed, and deionized water is added to the mixture. Add 100 parts and 0.5 part of a radical polymerizable surfactant (trade name “AQUALON HS10”, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., ammonium sulfate having a polymerizable unsaturated group and an oxyethylene group) A pre-emulsion was prepared using a mixer. On the other hand, the inside of the flask containing 45 parts of deionized water and 0.5 part of a radical polymerizable surfactant (“AQUALON HS10”) was purged with nitrogen, and then heated to a temperature of 80 ° C., and the internal solution was brought to a temperature of 80 ° C. While maintaining, 1 part of ammonium persulfate and 2% of the above pre-emulsion were added thereto, and 15 minutes after the addition, the remaining monomer emulsion was added dropwise over 2 hours, followed by aging for 2 hours. After aging, the mixture was cooled, and 3 parts of 10% by mass ammonia water was added dropwise as a neutralizing agent to obtain a maleimide group-containing acrylic resin emulsion (B-4).

Alkoxysilyl group-containing acrylic resin emulsion (B-5)
“Sanmor EW-102” (trade name, manufactured by Sanyo Chemical Industries, alkoxysilyl group-containing emulsion, solid content 40%) was used.

Preparation of pigment dispersion paste Production Example 20
The following composition was added to a stainless steel container, stirred for 10 minutes with a disper, and then dispersed for 5 minutes with a scan disk to obtain a pigment dispersion paste.
Pigment dispersion paste composition Water supply 400 parts Ethylene glycol 100 parts “Nopco Santo K” (manufactured by San Nopco, pigment dispersant) 30 parts
"Fuji Chemi HEC KF-100" (manufactured by Asahi Denka Co., Ltd., thickener) 10 parts "SN deformer-364" (manufactured by San Nopco, antifoaming agent) 20 parts titanium white 80 parts.

Production Example 1 of water-based coating composition
Using 200 parts of the base resin emulsion (B-1) obtained in Production Example 16 above, 15 parts of the acrylic resin solution (A-1) obtained in Production Example 1 and 140 parts of the pigment dispersion paste were used with a disper. While stirring, 0.8 parts of adipic acid dihydrazide and 10 parts of “Texanol” (trade name, 2,2,4-trimethylpentanediol monoisobutyrate manufactured by Eastman Kodak Co.) were added dropwise with stirring. A water-based coating composition (C-1) was prepared.

Examples 2 to 25 and Comparative Examples 1 to 4
In Example 1, except that the blending composition was as described in Table 2, it was carried out in the same manner as in Example 1 to obtain each aqueous coating composition.

Preparation of test coated plate “Esco” (epoxy-amine rust-preventing primer, manufactured by Kansai Paint Co., Ltd.) was applied to both sides of a 70 × 150 × 0.8mm bonded steel plate and left for 24 hours. Each of the aqueous coating compositions obtained as described above was applied with a brush at a coating amount of 240 g / m ² and dried for 2 hours under conditions of a temperature of 20 ° C. and a relative humidity of 75% to prepare each test coating plate. The samples were subjected to the performance test shown below. The results are shown in Table 2. In addition, about the test coating board of Example 20 containing a melamine, after apply | coating a water-based coating composition, it dried at 80 degreeC with the electric dryer for 10 minutes, and then baked at 140 degreeC for 30 minutes, and the test coating board was obtained. .

(Note 1) Polyisocyanate: “STAPHYLOID WD-220”, trade name, manufactured by Mitsui Chemicals Polyurethanes, hexamethylene diisocyanate-based water-dispersible polyisocyanate,
(Note 2) Carbodiimide: “CARBODILITE E-01”: trade name, manufactured by Nisshinbo Co., Ltd., water dispersible polycarbodiimide, carbodiimide equivalent 425, active ingredient 40%,
(Note 3) Oxazoline: “Epocross WS-500”, trade name, manufactured by Nippon Shokubai Co., Ltd., water-soluble oxazoline, oxazoline equivalent 220, active ingredient 40%,
(Note 4) Melamine: “Cymel 327”: trade name, manufactured by Mitsui Cytec Co., Ltd., melamine resin (* 1) compatibility: base resin emulsion, acrylic resin solution, and “Texanol” are combined in Table 2 so as to have a blending amount. A clear paint was prepared by mixing with the above, and the finished appearance of the clear coating film formed by coating this on a glass plate so as to have a dry film thickness of 60 μm was evaluated according to the following criteria.
◎: Transparent without turbidity,
○: Slightly white and cloudy, but transparent (visible through the other side)
Δ: White turbidity is observed, but there is transparency (the other side is seen through)
×: Extremely cloudy and no transparency (not visible through the other side).
(* 2) Contamination resistance test Each test coated plate is fixed at an angle of 30 ° on the south side of the building in Ota-ku, Tokyo, and left in that state for 3 months. It was evaluated with.
A: Dirt is not known compared to before leaving.
○: Slightly dirty as compared to before leaving, but the stain is not noticeable by washing with water.
(Triangle | delta): Dirt is conspicuous compared with before leaving, and some dirt is recognized even if washed with water.
X: Dirt is conspicuous as compared to before leaving, and it is recognized even after washing with water.
(* 3) One drop (about 15 μl) of deionized water is dropped on the surface of each hydrophilic test coating plate, and the contact angle of the water drop is “Contact Angle Meter CA-X150 type” (trade name, manufactured by Kyowa Chemical Co., Ltd.). It evaluated by measuring by. It shows that it is hydrophilic, so that a value is low.
A: Less than 55 °,
○: 55 ° or more and less than 70 °,
Δ: 70 ° or more and less than 75 °,
×: 75 ° or more.
(* 4) Weather resistance Each test coated plate was evaluated by subjecting it to a 1,000-hour weather resistance test using a sunshine weatherometer and calculating the gloss retention (%) by the following formula.
Gloss retention (%) = (60 ° gloss after test) / (60 ° gloss before test) × 100
A: 80% or more,
○: 70% or more and less than 80%,
Δ: 60% or more and less than 70%,
X: Less than 60%.
(* 5) Water resistance After each test coating plate was immersed in clean water at 20 ° C. for 7 days, the coated surface state was observed and evaluated according to the following criteria.
A: Very good,
○: Good,
Δ: Some blisters occur,
X: Blister occurs on the entire surface.

Claims (10)

A carbonyl group-containing copolymer (I) and a crosslinkable resin composition (II) are contained, and the copolymer (I) comprises a carbonyl group-containing polymerizable unsaturated monomer (a), a carboxyl group-containing polymerizable monomer. Obtained by solution polymerization of a monomer mixture containing a saturated monomer (b) and a hydrophilic polymerizable unsaturated monomer (c) other than the monomer (a) and the monomer (b) in the presence of a propylene glycol ether organic solvent. Total polymerization in which the copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) and the hydrophilic polymerizable unsaturated monomer (c) is used for the production of the copolymer (I). 30% by mass or more in the polymerizable unsaturated monomer, and the copolymerization ratio of the carboxyl group-containing polymerizable unsaturated monomer (b) is in the range of 0.1 to 70% by mass, and the hydrophilic polymerizable unsaturated monomer. -(C) is an alkyl (meth) acrylate having 1 to 2 carbon atoms in the ester part, a hydroxyl group-containing polymerizable unsaturated monomer, an alkoxy polyoxyalkylene group-containing polymerizable unsaturated monomer, an alkoxyalkyl (meth) acrylate, an amide A group-containing polymerizable unsaturated monomer, a morpholino group-containing polymerizable unsaturated monomer and at least one selected from the group consisting of a sulfonyl group-containing polymerizable unsaturated monomer,
And the crosslinkable resin composition (II) has a functional group capable of reacting with the functional group contained in the copolymer (I) or is self-crosslinking,
When the crosslinkable resin composition (II) has a functional group capable of reacting with the functional group contained in the copolymer (I), the crosslinkable resin composition (II) is a carbonyl group-containing emulsion polymer (IIa). And a hydrazine derivative, and a propylene glycol ether-based organic solvent is contained in the composition. The aqueous coating composition according to claim 1, wherein the hydrophilic polymerizable unsaturated monomer (c) is a polymerizable unsaturated monomer having a solubility in water at 25 ° C of 0.5 or more. The aqueous coating composition according to claim 1 or 2, wherein the carbonyl group-containing copolymer (I) has a weight average molecular weight in the range of 1000 to 50000. The aqueous coating composition according to any one of claims 1 to 3, wherein the carbonyl group-containing emulsion polymer (IIa) has a core-shell structure. The glass transition temperature of the copolymer composed of the polymerizable unsaturated monomer constituting the core is in the range of −40 to 30 ° C., and the glass transition temperature of the copolymer composed of the polymerizable unsaturated monomer constituting the shell is 0. The water-based coating composition according to claim 4, which is in the range of -80 ° C. The SP value of the carbonyl group-containing copolymer (I) is in the range of 9.0 to 13.0, and the SP value of the carbonyl group-containing emulsion polymer (IIa) is in the range of 8.0 to 10.0. The water-based coating composition according to claim 4 or 5, wherein the water-based coating composition is provided. The crosslinkable resin composition (II) has a functional group capable of reacting with the functional group contained in the copolymer (I), and the copolymer (I) and the crosslinkable resin composition (II) When the resin component contained has a hydroxyl group, the crosslinkable resin composition (II) further includes one selected from polyisocyanate and melamine resin, and the resin component contained in the crosslinkable resin composition (II) is a carboxyl group. The water-based coating composition according to any one of claims 1 to 6, wherein the crosslinkable resin composition (II) further comprises one selected from a polyoxazoline compound, a polycarbodiimide compound and a metal compound. The crosslinkable resin composition (II) contains a self-crosslinking resin, and the self-crosslinking resin has an unsaturated fatty acid group, an alkoxysilyl group, or a maleimide group. The water-based coating composition according to item. The solid content of the carbonyl group-containing copolymer (I) is in the range of 0.01 to 30% by mass with respect to the resin component contained in the crosslinkable resin composition (II). The water-based coating composition according to any one of the above. A coating method comprising applying the aqueous coating composition according to any one of claims 1 to 9 to a surface to be coated.