JP6271276B2 - Polymer particles, polymer dispersion, aqueous coating material and painted product - Google Patents

Description

  The present invention relates to polymer particles, a polymer dispersion, an aqueous coating material, and a coated product.

Conventionally, in the paint field, conversion from organic solvent-based paints to water-based paints has been attempted from the viewpoint of environmental protection and safety and health. However, water-based paints have the problem that the coating film appearance, weather resistance, water resistance, solvent resistance, and stain resistance of the coating film performance are lower than those of organic solvent-based paints.
Therefore, in order to solve these problems, a coating material containing an intra-particle mixture of resins having different properties has been proposed.

For example, Patent Document 1 describes a polymer in which an acrylic monomer is emulsion-polymerized in an aqueous dispersion of a urethane resin to mix the urethane resin and the acrylic polymer to form particles. Yes.
Patent Document 2 also describes a particulate polymer using a urethane resin and an acrylic polymer.
Patent Document 3 describes a composite film containing a urethane resin and an acrylic polymer obtained by reacting an acrylic monomer with a diol and a diisocyanate to synthesize a urethane prepolymer and then UV curing. Has been. It is also described that the composite film has N, N′-dimethylformamide (DMF) soluble content.

  In recent years, from the viewpoint of energy saving, it is required to lower the drying temperature and shorten the drying time in the drying process after coating. Therefore, a paint having water resistance and solvent resistance is required even under low temperature and short drying conditions.

JP 2006-274096 A JP 2008-88429 A JP 2009-120663 A

However, the dispersion of polymer particles described in Patent Document 1 has insufficient storage stability when used in an aqueous coating material, and the water resistance and solvent resistance of the coating film are insufficient.
Further, Patent Document 2 does not describe that the obtained dispersion of polymer particles is used for a coating material. Even if this dispersion of polymer particles is used for an aqueous coating material, the coating material for the aqueous coating material is used. Insufficient viscosity characteristics and storage stability, and water resistance of the coating film.
Moreover, patent document 3 is literature regarding the composite film obtained by UV-curing a urethane prepolymer, and is not related with a coating material.

An object of the present invention is to provide a polymer dispersion excellent in coating viscosity characteristics and storage stability when used in an aqueous coating material, and polymer particles contained in the polymer dispersion.
Furthermore, the present invention provides an aqueous coating material capable of forming a coating film excellent in water resistance and solvent resistance even when the drying conditions are low temperature and for a short time, and a coated article coated with the aqueous coating material. With the goal.

The present invention has the following configuration.
<1> Polymer particles containing urethane resin (A) and acrylic polymer (B) in the same particle, the gel of the polymer particles measured in N, N′-dimethylformamide (DMF) Polymer particles having a fraction of 10% or more.
<2> The polymer particles according to <1>, wherein the urethane resin (A) is a urethane resin having a sulfonic acid group.
<3> A monomer derived from a monomer in which the acrylic polymer (B) includes a monomer unit derived from a monomer having two or more radically polymerizable groups and having two or more radically polymerizable groups. The polymer particle according to <1> or <2>, wherein the unit ratio is 0.01 to 10% by mass with respect to the total mass of the urethane resin (A) and the acrylic polymer (B).
<4> The acrylic polymer (B) includes a monomer unit derived from an acid group-containing radical polymerizable monomer, and a ratio of the monomer unit derived from the acid group-containing radical polymerizable monomer is a urethane resin ( The polymer particles according to any one of <1> to <3>, which are 0.008 to 3.4% by mass relative to the total mass of A) and the acrylic polymer (B).
<5> A polymer dispersion containing the polymer particles according to any one of <1> to <4>.
<6> An aqueous coating material containing the polymer dispersion liquid according to <5>.
<7> A coated product to which the aqueous coating material according to <6> is applied.
<8> The coated product according to <7>, wherein the gloss retention of the coating film after being immersed in solvent naphtha for 30 seconds is 60% or more.

According to the present invention, it is possible to provide a polymer dispersion excellent in paint viscosity characteristics and storage stability when used in an aqueous coating material, and polymer particles contained in the polymer dispersion.
According to the present invention, there are further provided an aqueous coating material capable of forming a coating film having excellent water resistance and solvent resistance even under low temperature and short drying conditions, and a coated product coated with the aqueous coating material. it can.

  Hereinafter, the polymer particles of the present invention, a polymer dispersion containing the polymer particles, an aqueous coating material containing the polymer dispersion, and a coated product coated with the aqueous coating material will be described in detail.

<Polymer particles>
One aspect of the present invention is a polymer particle containing a urethane resin (A) and an acrylic polymer (B) in the same particle, and the N, N′-dimethylformamide (DMF) of the polymer particle. It is a polymer particle whose gel fraction measured in 10% or more.
Thus, a polymer dispersion containing polymer particles containing the urethane resin (A) and the acrylic polymer (B) in the same particle and having a gel fraction with respect to DMF of 10% or more is used as an aqueous coating material. When used, a coating film having excellent water resistance and solvent resistance can be formed even if the drying conditions are low temperature and short time.

  In one embodiment of the present invention, the gel fraction of the polymer particles with respect to DMF is preferably 15% or more and 99.5% or less, more preferably 15% or more and 95% or less, and more preferably 20% or more. 90% or less is particularly preferable. By setting the gel fraction with respect to DMF within these ranges, when a polymer dispersion containing polymer particles is used as an aqueous coating material, the film formability is improved, and the coating film is excellent in water resistance and solvent resistance. Can be formed.

In one embodiment of the present invention, the gel fraction of polymer particles relative to DMF can be determined, for example, by the following method.
A polymer dispersion of polymer particles containing the urethane resin (A) and the acrylic polymer (B) in the same particle is applied to a polypropylene plate so that the dry film thickness is 200 μm, and then at 23 ° C. for 24 hours. Dry to obtain a coating film. A sample is cut out from the obtained coating film, the weight of the sample is measured, and “weight of coating film before DMF immersion” is determined. The weight of the sample is preferably 0.035 to 0.045 g. Thereafter, the sample is placed in 20 ml of DMF and immersed at 23 ° C. for 24 hours. After soaking, DMF containing the sample is filtered using a tetrafluoroethylene resin (PTFE) filter. Further, the filter and the residue are dried at 105 ° C. for 3 hours and then cooled, and the “total weight of the filter and residue after immersion in DMF” is measured. The “gel weight of polymer particles” is determined by substituting “weight of coating film before DMF immersion”, “weight of filter”, and “total weight of filter and residue after DMF immersion” into the following formula (1). .
Gel fraction (%) = (“total weight of filter and residue after immersion in DMF” − “weight of filter”) / “weight of coating film before immersion in DMF”) × 100 (1)

  In one embodiment of the present invention, the polymer particles containing the urethane resin (A) and the acrylic polymer (B) in the same particle, for example, in an aqueous dispersion of the urethane resin (A), It can be produced by a method of polymerizing an acrylic monomer mixture.

[Urethane resin (A)]
In one embodiment of the present invention, the urethane resin (A) refers to a resin obtained by reacting a diol with a polyvalent isocyanate compound.

  A diol refers to an organic compound having two hydroxy groups in one molecule. Specific examples include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, Relatively low molecular weight diols such as neopentyl glycol, diethylene glycol, trimethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, hexanediol, cyclohexanedimethanol; and at least one of these diols Polyester diols obtained by polycondensation with at least one dicarboxylic acid such as adipic acid, sebacic acid, itaconic acid, maleic anhydride, terephthalic acid, isophthalic acid; polyethylene glycol, poly B propylene glycol, polycaprolactone diol, polytetramethylene ether diol, polyether diols and polycarbonate diols; polybutadiene diol, hydrogenated polybutadiene diol, polyacrylate diol. These diols may be used alone or in combination of two or more.

The polyvalent isocyanate compound refers to an organic compound having at least two isocyanate groups in one molecule, and examples thereof include aliphatic, alicyclic and aromatic polyvalent isocyanate compounds.
Specific examples of the polyvalent isocyanate compound include dicyclohexylmethane diisocyanate, 1,6-hexamethylene diisocyanate, isophorone diisocyanate, 1,3-cyclohexylene diisocyanate, 1,4-cyclohexylene diisocyanate, 2,4-tolylene diisocyanate, 2, , 6-tolylene diisocyanate, 4,4′-diphenylmethane diisocyanate, 2,4′-diphenylmethane diisocyanate, 2,2′-diphenylmethane diisocyanate, and the like. These polyvalent isocyanate compounds may be used alone or in combination of two or more. Among these, aliphatic or alicyclic isocyanates are preferable because the resulting urethane resin (A) has little yellowing.

  Examples of the method for producing the urethane resin (A) include a method of reacting the diol and the polyvalent isocyanate compound in ethers such as dioxane with a catalyst such as dibutyltin dilaurate.

The weight average molecular weight of the urethane resin (A) obtained by such a method is preferably 500 or more, more preferably 1000 or more from the viewpoint of improving the reactivity with the acrylic monomer mixture described later. Is more preferable. The upper limit of the weight average molecular weight is preferably 500,000 or less, and more preferably 100,000 or less.
Here, the “weight average molecular weight” means a value calculated by polystyrene conversion using gel permeation chromatography. Moreover, in one aspect of the present invention, the weight average molecular weight of the urethane resin (A) is preferably 500 to 500,000, and more preferably 1,000 to 100,000.

In one embodiment of the present invention, it is preferable to use an aqueous dispersion of the urethane resin (A) in which the urethane resin (A) is dispersed in water. When an aqueous dispersion of urethane resin (A) is used, for example, when emulsion polymerization of an acrylic monomer mixture in an aqueous dispersion of urethane resin (A) is performed, polymer particles can be stably produced. it can.
In one embodiment of the present invention, it is preferable to introduce a carboxy group and / or a sulfonic acid group into the urethane resin (A) from the viewpoint of good dispersibility in water.
Moreover, it is more preferable to use a urethane resin having a sulfonic acid group as the urethane resin (A). Thus, by using a urethane resin having a sulfonic acid group or a urethane resin having a carboxy group as the urethane resin (A), the acrylic monomer mixture described later has an acid group such as a carboxy group. In the case of containing an acid group-containing radical polymerizable monomer, the polymerization stability during emulsion polymerization is good. In addition, when the polymer dispersion containing the polymer particles of the present invention is used as an aqueous coating material, a storage stability is improved, and a coating film having excellent water resistance and hydrolysis resistance can be formed.

  In one embodiment of the present invention, the urethane resin having a sulfonic acid group is a method of reacting a polyol such as a diol, a polyvalent isocyanate compound, and a compound having a sulfonic acid group or a salt thereof; a polyol having a sulfonic acid group And a method of reacting a polyisocyanate compound and the like.

Examples of the compound having a sulfonic acid group or a salt thereof include hydroxysulfonic acid such as 1,7-dihydroxynaphthalenesulfonic acid; 2,4-diaminobenzenesulfonic acid, 3,4-diaminobutanesulfonic acid, 3,6- Examples thereof include aminosulfonic acids such as diamino-2-toluenesulfonic acid and N- (2-aminoethyl) -2-aminoethylsulfonic acid. These compounds having a sulfonic acid group or a salt thereof may be used alone or in combination of two or more.
Examples of polyols having sulfonic acid groups include polyols containing sulfonic acid groups such as 1,4-butanediol-2-sulfonic acid; sulfonate-containing polyester polyols, sulfonate-containing polyether polyols, and sulfonate-containing polyols. Examples include sulfonate-containing polyols such as polycarbonate polyols. These polyols having a sulfonic acid group may be used alone or in combination of two or more.

The average particle diameter of the urethane resin (A) in the aqueous dispersion of the urethane resin (A) is preferably 1000 nm or less, and more preferably 500 nm or less as an average particle diameter according to the cumulant analysis result. If the average particle diameter of the urethane resin (A) is within the above range, for example, an aqueous dispersion of the urethane resin (A) and a storage when the polymer dispersion containing the polymer particles of the present invention is used as an aqueous coating material. Stability, water resistance and solvent resistance of the coating are further improved.
In one embodiment of the present invention, the average particle diameter of the urethane resin (A) is preferably 10 nm or more from the viewpoint of the viscosity property of the paint and the storage stability when used in an aqueous coating material.
That is, in one embodiment of the present invention, the average particle size of the urethane resin (A) in the aqueous dispersion of the urethane resin (A) is preferably 10 to 1000 nm, and more preferably 10 to 500 nm.

The content of the urethane resin (A) in the aqueous dispersion of the urethane resin (A) is preferably 10% by mass or more and 70% by mass or less with respect to the total mass of the aqueous dispersion of the urethane resin (A). More preferably, it is 25 mass% or more and 60 mass% or less.
If the content of the urethane resin (A) in the aqueous dispersion of the urethane resin (A) is within the above range, the polymer dispersion obtained by polymerizing the acrylic monomer mixture in the aqueous dispersion The solid content concentration can be adjusted to a range of 10 to 80% by mass. If the solid content concentration of the polymer dispersion is within the above range, the paintability when the polymer dispersion is used as an aqueous coating material becomes good. The solid content concentration of the polymer dispersion refers to the ratio (% by mass) of the polymer particles contained in the polymer dispersion.

As an aqueous dispersion of such a urethane resin (A), a commercially available aqueous dispersion of urethane polymer (urethane dispersion: PUD) can be used as it is.
Specifically, Daiichi Kogyo Seiyaku Co., Ltd .: Superflex 110, Superflex 150, Superflex 210, Superflex 300, Superflex 420, Superflex 460, Superflex 470, Superflex 500M, Superflex 620, Superflex 650, Superflex 740, Superflex 820, Superflex 840, manufactured by Sumika Bayer Urethane Co., Ltd .: Bihydrol UH2606, Bihydrol UHXP2648, Bihydrol UHXP2650, Impraneil DLC-F, Impranele DLN, Impranele DLS, Impraneil XP2611, Implanil LPRSC 1380, Implanil LPRSC1537, Imp Neil LPRSC 1554, manufactured by Dainippon Ink & Chemicals, Inc .: Hydran HW-301, HW-310, HW-311, HW-312B, HW-333, HW-340, HW-350, HW-375, HW-920, HW-930, HW-940, HW-950, HW-970, AP-10, AP-20, ECOS3000, manufactured by Sanyo Chemical Industries, Ltd .: U-coat UWS-145, Permarin UA-150, Permarin UA-200, Permarin UA-300, Permarin UA-310, Yucote UX-320, Permarin UA-368, Permarin UA-385, Yucote UX-2510, manufactured by Nikka Chemical Co., Ltd .: Neo Sticker 100C, Evaphanol HA-107C, Evaphanol HA-50C , Evaphanol HA-170, Evaf Nord HA-560, (Ltd.) ADEKA Corporation: ADEKA BONTIGHTER UHX-210, and the like ADEKA BONTIGHTER UHX-280.
In addition, as an aqueous dispersion of a urethane resin having a sulfonic acid group, a commercially available urethane aqueous polymer dispersion can be used as it is. Commercially available products include “F-8082D” manufactured by Daiichi Kogyo Seiyaku Co., Ltd., “Baihydrol UH650” manufactured by Sumika Bayer Urethane Co., Ltd., “Imperil DLP-R”, “Imperil DLU”, “Imperil LP” RSC 3040 ", Sanyo Chemical Industries" Permarin UXA-3005 ", etc. are mentioned.

[Acrylic polymer (B)]
In one embodiment of the present invention, the acrylic polymer (B) is obtained by radical polymerization of an acrylic monomer mixture (a mixture of radical polymerizable monomers) in an aqueous dispersion of the urethane resin (A). Can be obtained.
In one embodiment of the present invention, the acrylic monomer mixture preferably includes a monomer having a radical polymerizable group as the acrylic monomer, and a single monomer having two or more radical polymerizable groups. More preferably, it contains a monomer. Here, the radical polymerizable group is a group containing a carbon-carbon unsaturated double bond capable of radical polymerization, a carbon-carbon unsaturated triple bond, a ring capable of radical ring-opening polymerization, and the like.

[Acrylic monomer mixture]
In one embodiment of the present invention, examples of the acrylic monomer contained in the acrylic monomer mixture (hereinafter sometimes simply referred to as “monomer mixture”) include, for example, methyl (meth) acrylate, ethyl (Meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, pentyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, 2-ethylhexyl Alkyl having 1 to 22 carbon atoms (such as (meth) acrylate, nonyl (meth) acrylate, tridecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, isostearyl (meth) acrylate) ( (Meth) acrylates; cyclohexyl Cycloalkyl (meth) acrylates such as (meth) acrylate, methylcyclohexyl (meth) acrylate, and t-butylcyclohexyl (meth) acrylate; ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di ( (Meth) acrylate, propylene glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate, 2-hydroxy-1,3-di (meth) acryloxypropane, 2,2-bis [4- (acryloxyethoxy) phenyl] propane, 2,2-bis [4- (methacrylic) Loxyethoxy) phenyl] propane, 2,2-bis [4- (acryloxy polyethoxy) phenyl] propane, 2,2-bis [4- (methacryloxy polyethoxy) phenyl] propane, 2-hydroxy-1-acryloxy-3 -Methacryloxypropane, ethylene oxide modified bisphenol A di (meth) acrylate, propylene oxide modified bisphenol A di (meth) acrylate, ethylene oxide modified hydrogenated bisphenol A di (meth) acrylate, propylene oxide modified hydrogenated bisphenol A di (meth) ) Epoxy (meth) acrylates, polyoxyalkyls obtained by adding hydroxyalkyl (meth) acrylates such as hydroxy (meth) acrylate to diglycidyl ether of acrylate and bisphenol A Diester compound of diol such as bisphenol A di (meth) acrylate and (meth) acrylic acid; trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, penta Compounds having 3 or more hydroxyl groups per molecule such as erythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and (meth) acryl Acid polyester compounds: allyl (meth) acrylate, divinylbenzene, triallyl isocyanurate, diallyl iso (tere) phthalate, diallyl isocyanurate, diary maleate Monomers having two or more radically polymerizable groups such as tris (2-acryloyloxyethylene) isocyanurate and ε-caprolactone-modified tris (acryloxyethyl) isocyanurate, conjugated dienes such as 1,3-butadiene and isoprene Monomer, acrylic acid, methacrylic acid, itaconic acid, maleic acid, crotonic acid, β-carboxyethyl acrylate and other acid group-containing radical polymerizable monomers, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl Hydroxyl-containing radical polymerizable monomers such as (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, γ- (meth) acryloyloxypropylmethyldimethoxysilane, γ- (meth) Acryloyloxypropyltrimethoxy Hydrolyzable silyl group-containing radical polymerizable monomers such as silane; alkyl group-terminated polyalkylene oxide group-containing radical polymerizable monomers such as methoxypolyethylene oxide mono (meth) acrylate; oxiranes such as glycidyl (meth) acrylate Group-containing radically polymerizable monomer; carbonyl group-containing ethylenically unsaturated monomer such as diacetone acrylamide; 1,2,2,6,6-pentamethyl-4-piperidyl (meth) acrylate, 2,2,6 , 6-Pentamethyl-4-piperidyl (meth) acrylate and the like (meth) acrylate having light stabilizing action; 2- [2′-hydroxy-5 ′-(meth) acryloyloxyethylphenyl] -2H-benzotriazole, etc. (Meth) acrylate having a UV-absorbing component of ) Aminoalkyl (meth) acrylates such as acrylate; Amide group-containing radical polymerizable monomers such as (meth) acrylamide; Metal-containing radical polymerizable monomers such as zinc di (meth) acrylate; (Meth) acrylonitrile Other (meth) acrylic monomers such as benzyl (meth) acrylate, isobornyl (meth) acrylate, and methoxyethyl (meth) acrylate; aromatic vinyl monomers such as styrene and methylstyrene; vinyl acetate, chloride And radical polymerizable monomers such as vinyl and ethylene. In the present invention, the acrylic monomer mixture (a mixture of radical polymerizable monomers) is one or more, preferably two or more selected from these acrylic monomers (radical polymerizable monomers). Are used in combination.

Although it does not specifically limit as long as it has the effect of this invention as a monomer mixture, It is preferable that the monomer which has two or more radically polymerizable groups is included. By containing a monomer having two or more radically polymerizable groups, the gel fraction of the polymer particles with respect to DMF is increased, the water resistance and solvent resistance of the coating film are further improved, and particularly the solvent resistance is improved. Therefore, it is preferable.
Specific examples of the monomer having two or more radically polymerizable groups include the above-mentioned monomers. Among these, ethylene glycol di (meth) acrylate, allyl (meth) acrylate, Radical polymerizable monomers such as allyl isocyanurate, diallyl iso (tere) phthalate, diallyl isocyanurate, and diallyl maleate are preferred. Monomers having two or more radically polymerizable groups may be used alone or in combination of two or more.

In one embodiment of the present invention, the proportion of the monomer having two or more radically polymerizable groups, that is, the charged amount is based on the total mass of the urethane resin (A) and the acrylic monomer mixture. It is preferable that it is 0.01-10 mass%. A monomer unit derived from a monomer in which the acrylic polymer (B) has two or more radically polymerizable groups by blending a monomer having two or more radically polymerizable groups in such a ratio. And the proportion of monomer units derived from the monomer having two or more radically polymerizable groups is 0.01 to the total mass of the urethane resin (A) and the acrylic polymer (B). Since it can be 10 mass%, it is preferable.
That is, in one aspect of the present invention, the acrylic polymer (B) includes a monomer unit derived from a monomer having two or more radically polymerizable groups, and two or more of the radically polymerizable groups. It is preferable that the ratio of the monomer unit derived from the monomer is 0.01 to 10% by mass with respect to the total mass of the urethane resin (A) and the acrylic polymer (B).
If the ratio of the monomer unit derived from a monomer having two or more radically polymerizable groups is 0.01% by mass or more with respect to the total mass of the urethane resin (A) and the acrylic polymer (B) A coating film excellent in solvent resistance and water resistance can be obtained. Moreover, if it is 10 mass% or less, the coating film excellent in solvent resistance and water resistance is obtained, without reducing a softness | flexibility, frost damage resistance, and chipping resistance.
Further, the charging amount of the monomer having two or more radically polymerizable groups is more preferably 0.02 to 8% by mass with respect to the total mass of the urethane resin (A) and the acrylic monomer mixture. Preferably, it is 0.03 to 6% by mass, and most preferably 0.04 to 4.5% by mass.

In one embodiment of the present invention, an appropriate amount of an acid group-containing radical polymerizable monomer is contained in the acrylic monomer mixture, so that the storage stability of the aqueous coating material and the water resistance of the coating film are increased. This is preferable. This is preferable because the acrylic polymer (B) contains an appropriate amount of a monomer unit derived from an acid group-containing radical polymerizable monomer.
Examples of the acid group-containing radical polymerizable monomer include the above-mentioned radical polymerizable monomers containing a carboxy group. These monomers may be used alone or in combination of two or more. Among these, acrylic acid and methacrylic acid are preferable.

In one embodiment of the present invention, the use ratio of the acid group-containing radical polymerizable monomer, that is, the charged amount is 0.008 to 3 with respect to the total mass of the urethane resin (A) and the acrylic monomer mixture. It is preferably 4% by mass. By blending the acid group-containing radical polymerizable monomer at such a use ratio, the acrylic polymer (B) contains the monomer unit, and the monomer unit derived from the acid group-containing radical polymerizable monomer. Is preferably 0.008 to 3.4% by mass with respect to the total mass of the urethane resin (A) and the acrylic polymer (B).
That is, in one aspect of the present invention, the acrylic polymer (B) includes a monomer unit derived from an acid group-containing radical polymerizable monomer, and the monomer unit derived from the acid group-containing radical polymerizable monomer. Is preferably 0.008 to 3.4% by mass with respect to the total mass of the urethane resin (A) and the acrylic polymer (B). The use ratio of the acid group-containing radical polymerizable monomer is more preferably 0.03 to 3.2% by mass, still more preferably 0.1 to 2.5% by mass, and Most preferably, it is 1-1.5 mass%.

In one embodiment of the present invention, the acrylic monomer mixture preferably contains a hydroxyl group-containing radical polymerizable monomer. When an acrylic monomer mixture containing a hydroxyl group-containing radical polymerizable monomer is used, an acrylic polymer containing a hydroxyl group can be produced, and further, a polymer containing an acrylic polymer containing a hydroxyl group in the same particle. Combined particles can be produced.
Thus, the polymer particle which contains the acrylic polymer which has a hydroxyl group in the same particle can perform a crosslinking reaction with hardening | curing agents, such as a melamine crosslinking agent and an isocyanate hardening | curing agent, for example. Therefore, by using a polymer particle containing an acrylic polymer having a hydroxyl group together with a curing agent such as a melamine crosslinking agent or an isocyanate curing agent and using it as an aqueous coating material, the water resistance and solvent resistance of the resulting coating film, etc. Can be improved. The polymer particles are also excellent in dispersion stability in an aqueous medium and an aqueous coating material.

Examples of such a hydroxyl group-containing radical polymerizable monomer include the above-mentioned monomers. Among these, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3- Hydroxypropyl (meth) acrylate and 4-hydroxybutyl (meth) acrylate are preferred. A hydroxyl-containing radically polymerizable monomer may be used individually by 1 type, or may use 2 or more types together.
In one embodiment of the present invention, the use ratio of the hydroxyl group-containing radical polymerizable monomer, that is, the charged amount is the stability of the obtained polymer dispersion in an aqueous medium, the water resistance of the resulting coating film, and the solvent resistance. In view of the above, 0.1 to 10% by mass is preferable with respect to the total mass of the urethane resin (A) and the acrylic monomer mixture.
By blending the hydroxyl group-containing radical polymerizable monomer in such a use ratio, the acrylic polymer (B) contains a monomer unit derived from the hydroxyl group-containing radical polymerizable monomer, and the urethane resin (A) And the ratio of the monomer unit derived from the hydroxyl group-containing radical polymerizable monomer to the total mass of the acrylic polymer (B) is preferably 0.1 to 10% by mass. Moreover, as for the usage-amount of the said hydroxyl-containing radically polymerizable monomer, 0.3-8 mass% is more preferable with respect to the total mass of a urethane resin (A) and an acryl-type monomer mixture, 0.5- 5% by mass is particularly preferred.

In one embodiment of the present invention, the blending ratio of the urethane resin (A) and the acrylic monomer mixture is not particularly limited as long as it has the effects of the present invention, but the urethane resin (A) and the acrylic heavy polymer in the polymer particles are not limited. It is preferable that the mass ratio with the coalesced (B) is determined so as to be within a preferable range described later.
That is, in one embodiment of the polymer particles of the present invention, the mass ratio of the urethane resin (A) and the acrylic monomer mixture is urethane resin (A) / acrylic monomer mixture = (10 to 90). / (90-10) is preferable, (15-80) / (85-20) is more preferable, (20-70) / (80-30) is still more preferable, (25 ~ 60) / (75-40) is particularly preferred. In this case, the total mass of the urethane resin (A) and the acrylic monomer mixture is 100.
By blending the urethane resin (A) and the acrylic monomer mixture at such a mass ratio, the mass ratio of the urethane resin (A) and the acrylic polymer (B) in the resulting polymer particles. Can be the same ratio.
That is, if the mass ratio of the urethane resin (A) is in the range of 10 to 90% by mass with respect to the total mass of the urethane resin (A) and the acrylic polymer (B), the resin compatibility, the coating machine The drying property, water resistance, and solvent resistance of the coating film are improved without deteriorating the detergency. Particularly in the range of 25 to 60% by mass, the gel fraction with respect to DMF is increased, the water resistance and solvent resistance of the coating film are further improved, and the solvent resistance is particularly excellent.
That is, in one aspect of the present invention, the gel fraction of the polymer particles to DMF can be controlled by the ratio of the urethane resin (A) to the total mass of the urethane resin (A) and the acrylic polymer (B). Is possible.

Further, in one aspect of the present invention, the polymer particle includes a urethane resin having a sulfonic acid group and an acrylic polymer including a monomer unit derived from an acid group-containing radical polymerizable monomer in the same particle. The surface acid value measured by potentiometric titration is preferably 0.1 to 19 mgKOH / g.
The urethane resin (A) is a urethane resin having a sulfonic acid group, and the acrylic monomer mixture further contains an acid group-containing radically polymerizable monomer having an acid group such as a carboxy group. Polymerization stability is improved. In addition, the storage stability of the aqueous coating material is improved, and a coating film having excellent water resistance and hydrolysis resistance can be formed.

In addition, when the surface acid value of the polymer particles is 0.1 mgKOH / g or more, the viscosity property of the paint when used as an aqueous coating material is easily developed, the storage stability is improved, and when the surface acid value is 19 mgKOH / g or less. In addition, the coating viscosity characteristics and the storage stability are improved when an aqueous coating material is used without reducing the polymerization stability and the water resistance of the coating film. The surface acid value is more preferably 0.5 to 17.5 mgKOH / g, further preferably 1 to 10 mgKOH / g, and particularly preferably 1 to 7 mgKOH / g.
Here, the “surface acid value” refers to a value expressed in milligrams of the amount of potassium hydroxide necessary to neutralize the acidic component present on the surface of the particles contained in 1 g of the polymer. .
The “potentiometric titration method” is a method for determining an end point by measuring a change in potential difference corresponding to a change in concentration of a target component in a solution. The surface acid value of the polymer particles can be determined by conducting potentiometric titration with a known concentration of polymer dispersion as potassium titrant.

In one embodiment of the present invention, the average particle size of the polymer particles is 10 to 1000 nm from the viewpoints of film formability, water resistance, water absorption resistance, hydrolysis resistance, and solvent resistance of the coating film. Is preferably 30 to 500 nm, more preferably 50 to 400 nm, and particularly preferably 70 to 300 nm.
In this specification, the average particle size of the polymer particles is a value calculated by cumulant analysis after measurement at room temperature (25 ° C.) using a dense particle size analyzer FPAR-1000 manufactured by Otsuka Electronics Co., Ltd. is there.

(Method for producing polymer particles)
In one embodiment of the present invention, the method for producing the polymer particles contained in the same particles as the urethane resin (A) and the acrylic polymer (B) is not particularly limited as long as it has the effects of the present invention. By polymerizing the monomer mixture in an aqueous dispersion of urethane resin (A), a dispersion (polymer dispersion) in which polymer particles are dispersed in an aqueous medium can be obtained.
The polymerization of the acrylic monomer mixture in the urethane resin (A) can be performed by a known polymerization method such as a suspension polymerization method or an emulsion polymerization method. In particular, it is desirable to obtain a polymer dispersion in the form of an emulsion by an emulsion polymerization method from the viewpoint of various physical properties such as storage stability of the aqueous coating material, water resistance of the coating film, and solvent resistance.
Emulsion polymerization can employ, for example, a known method in which an acrylic monomer mixture is supplied into a polymerization system in the presence of a surfactant and polymerization is performed with a radical polymerization initiator.
The polymerization of the acrylic monomer mixture may be one-stage polymerization or two-stage or more multi-stage polymerization.

In one embodiment of the present invention, from the viewpoint of increasing the gel fraction of the polymer particles obtained with respect to DMF and improving the film formability, two or more stages of multistage polymerization are used, and the stage before the final stage is used. The acrylic monomer mixture to be used preferably contains a monomer having two or more radically polymerizable groups. Thereby, the water resistance and solvent resistance of the coating film are further improved.
Furthermore, from the viewpoint of localizing the acid group derived from the acid group-containing radical polymerizable monomer on the surface layer of the polymer particles, an acrylic monomer used at least in the final stage using multistage polymerization of two or more stages. The body mixture preferably contains an acid group-containing radical polymerizable monomer. Thereby, the storage stability of the aqueous coating material and the water resistance of the coating film are improved. Moreover, the gel fraction with respect to DMF of a polymer particle goes up, and solvent resistance improves more.

The method of supplying the acrylic monomer mixture into the polymerization system is not particularly limited as long as it has the effect of the present invention; a method of dropping the acrylic monomer mixture; using a surfactant and water, Examples thereof include a method of preparing a pre-emulsion liquid in which an acrylic monomer mixture is pre-emulsified and dispersed, and dropping the pre-emulsion liquid; a method of charging the acrylic monomer mixture all together. In the case of multistage polymerization, two or more of these methods may be used in combination. When adopting multistage polymerization of two or more stages, the first stage adopts the technique of charging the acrylic monomer mixture in a lump, and the second and subsequent stages adopt the technique of dropping the pre-emulsion liquid. Is preferred.
The acrylic polymer (B) is uniformly formed inside the urethane resin (A) by adding the first stage acrylic monomer mixture all at once and performing emulsion polymerization, as compared with the drop polymerization. Acrylic polymer (B) can be made into a high molecular weight body by batch polymerization. As a result, the gel fraction of the obtained polymer particles with respect to DMF increases, and the water resistance and solvent resistance of the coating film are improved. In addition, for the second and subsequent stages, the polymerization stability is improved by emulsion polymerization by a technique of dropping a pre-emulsion solution.

[Polymerization initiator]
As the polymerization initiator used for the polymerization of the acrylic monomer mixture, those generally used for radical polymerization can be used, for example, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate and the like. Azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-) 2,4-dimethylvaleronitrile), oil-soluble azo compounds such as 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile; 2,2′-azobis {2-methyl-N- [1,1- Bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl-N- [2- (1-hydroxyethyl)] propionamide 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2′-azobis [2- (5-methyl-2-imidazolin-2-yl) Propane] and its salts, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and its salts, 2,2′-azobis [2- (3,4,5,6-tetrahydropyrimidine -2-yl) propane] and its salts, 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) and its salts, 2,2′-azobis {2- [1- (2- Hydroxyethyl) -2-imidazolin-2-yl] propane} and salts thereof, 2,2′-azobis (2-methylpropionamidine) and salts thereof, 2,2′-azobis [N- (2-carboxyethyl) -2 Water-soluble azo compounds such as methylpropionamidine] and salts thereof; benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobuty Organic peroxides such as a rate are listed.
These initiators may be used alone or in combination of two or more.

The addition amount of the radical polymerization initiator used in the first step is 0.001 to 10 parts by mass when the total mass of the acrylic monomer mixture provided in the first step is 100 parts by mass. It is preferable. Taking into consideration the progress of polymerization and control of the reaction, it is more preferably 0.005 to 10 parts by mass. Moreover, it is still more preferable that it is 0.005-1 mass part from a viewpoint of the water resistance, solvent resistance, and a weather resistance improvement by high molecular weight increase of the polymer particle finally obtained. Further, from the viewpoint of reducing the coarse particle ratio of the finally obtained polymer dispersion, it is more preferably 0.005 to 0.5 parts by mass, still more preferably 0.005 to 0.2 parts by mass, particularly preferably. Is 0.005 to 0.09 parts by mass.
Here, the “rough particle ratio” means that the polymer is coalesced during the polymerization and the average particle diameter is in the form of particles exceeding 1 μm. For example, the measurement of the particle diameter or after the polymerization Evaluation can be made by measuring the weight of the particulate polymer remaining on the mesh after filtration through a mesh or the like.

The addition amount of the radical polymerization initiator used in the second and subsequent steps is 0.01 to 10 parts by mass when the total mass of the acrylic monomer mixture provided to each stage is 100 parts by mass. Is preferred. Among these, it is more preferable that the amount is 0.02 to 5 parts by mass in consideration of polymerization progress and reaction control.
In the polymerization, it is preferable to use a reducing agent such as sodium bisulfite, ferrous sulfate, ascorbate or Rongalite in combination with the above radical polymerization initiator.
Among these, a combination of organic peroxides such as t-butyl hydroperoxide, ferrous sulfate, ascorbate, etc. is adopted from the viewpoint of polymerization progress, water resistance, weather resistance, and solvent resistance of the coating film. More preferably. By employing this combination, the gel fraction with respect to DMF increases, and in particular, the solvent resistance of the coating film is improved.

[emulsifier]
In one embodiment of the present invention, an emulsifier may be used as necessary. When an emulsifier is used, the polymerization stability during emulsion polymerization can be improved, and aggregates can be reduced. In this case, the obtained polymer dispersion contains an emulsifier.
Usually, the content of the emulsifier is preferably 0.05 to 10 parts by mass, more preferably 0.00 when the total mass of the acrylic monomer mixture supplied to each stage is 100 parts by mass. 1 to 5 parts by mass, more preferably 0.5 to 2 parts by mass.
As the emulsifier, the following anionic, cationic and nonionic surfactants and reactive surfactants can be used.
Anionic surfactants include potassium oleate, sodium laurate, sodium dodecylbenzene sulfonate, sodium alkane sulfonate, sodium alkyl naphthalene sulfonate, sodium dialkyl sulfosuccinate, polyoxyethylene alkyl ether sodium sulfate, polyoxyethylene alkyl Non-reactive surfactants such as sodium allyl ether sulfate, polyoxyethylene alkyl phosphate ester, polyoxyethylene alkyl allyl phosphate ester, and alkyl allyl sulfosuccinate (eg, Sanyo Kasei Co., Ltd .: Eleminol (registered trademark) JS-) 2, JS-20, manufactured by Kao Corporation: LATEMUL (registered trademark) S-180A, S-180, etc.), polyoxyethylene alkylpropenyl phenyl ether Ammonium sulfate ammonium salt (for example, Aqualon (registered trademark) HS-10, HS-5, BC-10, BC-5 and the like manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), α-sulfo-ω- (1 -(Nonylphenoxy) methyl-2- (2-propenyloxy) ethoxy) -poly (oxy-1,2-ethanediyl) ammonium salt (for example, manufactured by Asahi Denka Kogyo Co., Ltd .: Adecalia Soap (registered trademark) SE-) 10, SE-1025A, and the like), polyoxyethylene-1- (allyloxymethyl) alkyl ether sulfate ammonium salt (for example, manufactured by Daiichi Kogyo Seiyaku Co., Ltd .: Aqualon (registered trademark) KH-10) Α-sulfo-ω- (1- (alkoxy) methyl-2- (2-propenyloxy) ethoxy) -poly (oxy-1,2-ethanedi) Yl) ammonium salt (for example, manufactured by Asahi Denka Kogyo Co., Ltd .: Adecalia Soap (registered trademark) SR-10, SR-1025 etc.), polyoxyalkylene alkenyl ether ammonium sulfate salt (for example, manufactured by Kao Corporation) Reactive surfactants such as LATEMUL (registered trademark) PD-104).
Examples of the cationic surfactant include non-reactive surfactants such as stearylamine hydrochloride, lauryltrimethylammonium chloride, and trimethyloctadecylammonium chloride.
Nonionic surfactants include non-reactive surfactants such as polyoxyethylene alkyl ether, polyoxyethylene alkyl allyl ether, polyoxyethyleneoxypropyl block polymer, polyethylene glycol fatty acid ester, polyoxyethylene sorbitan fatty acid ester, α- Hydro-ω- (1-alkoxymethyl-2- (2-propenyloxy) ethoxy) -poly (oxy-1,2-ethanediyl)) (Asahi Denka Kogyo Co., Ltd .: Adeka Soap ER-10, ER- 20, ER-30, ER-40), polyoxyethylene alkyl propenyl phenyl ether (Daiichi Kogyo Seiyaku Co., Ltd .: Aqualon RN-20, RN-30, RN-50), polyoxyalkyl alkenyl ether (Kao ( Co., Ltd .: Laterum PD-420, PD -430, PD-450) and the like.
Moreover, an amphoteric surfactant can also be used as an amphoteric component.
These emulsifiers can be used alone or in combination of two or more.

[Basic compounds]
In one embodiment of the present invention, the polymer dispersion is preferably adjusted to a pH of about 6.5 to 11.0 by adding a basic compound after polymerization. This improves the stability of the polymer dispersion and the storage stability of the aqueous coating material.
Examples of such basic compounds include ammonia, triethylamine, propylamine, dibutylamine, amylamine, 1-aminooctane, 2-dimethylaminoethanol, ethylaminoethanol, 2-diethylaminoethanol, 1-amino-2-propanol. 2-amino-1-propanol, 2-amino-2-methyl-1-propanol, 3-amino-1-propanol, 1-dimethylamino-2-propanol, 3-dimethylamino-1-propanol, 2-propyl Examples include aminoethanol, ethoxypropylamine, aminobenzyl alcohol, morpholine, sodium hydroxide, and potassium hydroxide. Among these, from the viewpoint of the stability of the polymer dispersion, amine-based compounds are preferable, and 2-dimethylaminoethanol is preferably used.

<Polymer dispersion>
In one embodiment of the present invention, the polymer dispersion is obtained by dispersing the aforementioned polymer particles in an aqueous medium. The solid content concentration (concentration of polymer particles) in the polymer dispersion is preferably 10 to 80% by mass, and more preferably 20 to 70% by mass. If the solid content concentration in the polymer dispersion is 10 to 80% by mass, it is preferable because it is easy to adjust the viscosity when preparing an aqueous coating material and the final solid content.

<Water-based coating material>
In one aspect of the present invention, the aqueous coating material contains a polymer dispersion and preferably contains various additives.
Examples of additives include various pigments, resin beads, antifoaming agents, pigment dispersants, leveling agents, anti-sagging agents, curing catalysts, matting agents, ultraviolet absorbers, light stabilizers, antioxidants, and heat resistance. Various additives such as an improver, a slip agent, a preservative, a plasticizer, a thickener, and a solvent can be used, and one or more of these can be used.
In addition, other polymer particles (for example, polyester resins, polyurethane resins, acrylic resins, acrylic silicone resins, silicone resins, fluorine resins, epoxy resins, polyolefin resins, alkyd resins) may be used for aqueous coating materials. Dispersed particles composed of other polymers, etc.), water-soluble resin / viscosity control agent, amino resin, polyisocyanate compound, blocked polyisocyanate compound, melamine resin, urea resin, carboxyl group-containing compound, carboxyl group-containing resin, epoxy A curing agent such as a group-containing resin, an epoxy group-containing compound, or a carbodiimide group-containing compound may be mixed.
Examples of the pigment include a color pigment, an extender pigment, and a glitter pigment.
Examples of coloring pigments include titanium oxide, zinc oxide, carbon black, molybdenum red, Prussian blue, cobalt blue, azo pigments, phthalocyanine pigments, quinacridone pigments, isoindoline pigments, selenium pigments, and perylene pigments. Is mentioned.
Examples of extender pigments include clay, kaolin, barium sulfate, barium carbonate, calcium carbonate, talc, silica, and alumina white.
Examples of bright pigments include 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, glass flake, hologram And pigments.
One or more of these can be used.

In one embodiment of the present invention, the aqueous coating material may further contain a solvent.
As the solvent, those usually used for water-based paints can be used. Examples of such a solvent include linear, branched or cyclic aliphatic alcohols having 5 to 14 carbon atoms; alcohols containing an aromatic group; general formula HO— (CH ₂ CHXO) _p — Represented by R ₄ (R ₄ is a linear or branched alkyl group having 1 to 10 carbon atoms, X is a hydrogen atom or a methyl group, and p is an integer of 5 or less). ) ethylene glycol or (poly) monoethers and propylene glycol; general formula _{R 5 COO- (CH 2 CHXO)} q -R 6 (R 5, R 6 is a straight-chain or branched having 1 to 10 carbon atoms X is a hydrogen atom or a methyl group, and q is an integer of 5 or less.) (Poly) ethylene glycol ether ester or (poly) propylene glycol ether Steal; aromatic organic solvents such as toluene and xylene; mono- or diisobutyrate of 2,2,4-trimethyl-1,3-pentanediol, 3-methoxybutanol, 3-methoxybutanol acetate, 3-methyl- Examples include 3-methoxybutanol and 3-methyl-3-methoxybutanol acetate.
Among these, linear, branched or cyclic aliphatic alcohols having 5 to 14 carbon atoms are preferable, alcohol based hydrophobic solvents having 7 to 14 carbon atoms are more preferable, 1-octanol, 2-octanol, Particularly preferred is at least one alcoholic hydrophobic solvent selected from the group consisting of 2-ethyl-1-hexanol, ethylene glycol mono-2-ethylhexyl ether, propylene glycol mono n-butyl ether, and dipropylene glycol mono n-butyl ether.

The concentration of the polymer particles in the aqueous coating material is preferably 1 to 80% by mass, and more preferably 2 to 70% by mass. If it is this range, it is excellent in a coating-material viscosity characteristic, the water resistance of a coating film, and solvent resistance.
Further, when the aqueous coating material contains other polymer particles other than the polymer particles of the present invention, the proportion of the other polymer particles is 5000 parts by mass or less with respect to 100 parts by mass of the polymer particles of the present invention. It is preferable from the viewpoints of paint viscosity characteristics, water resistance and solvent resistance of the coating film.

Another embodiment of the present invention is a polymer particle containing a urethane resin (A) and an acrylic polymer (B) in the same particle, and N, N′-dimethylformamide (DMF) of the polymer particle. Use of a polymer dispersion containing polymer particles having a gel fraction of 10% or more as a raw material for an aqueous coating material, or a polymer dispersion containing polymer particles of the present invention as a raw material This is a method for producing an aqueous coating material.
When the polymer dispersion containing the polymer particles of the present invention is used as a raw material for the aqueous coating material, it is preferable to contain a solvent and a thickener additive in addition to the polymer dispersion.
In one aspect of the present invention, the method for producing an aqueous coating material is preferably a method including a step of mixing the polymer dispersion, a solvent, and a thickener using a disper.
Moreover, in one aspect of the present invention, 1 to 70% by mass of the polymer particles, 0.1 to 30% by mass of the solvent, and 0.01 to 5% of the thickener based on the total mass of the aqueous coating material. It is preferable that it contains the mass%.

<Painted object>
The coated product of the present invention is a coated product having a coating film to which an aqueous coating material containing the polymer dispersion of the present invention is applied.
There is no particular restriction on the location where the aqueous coating material is applied to form a coating film, and various articles (hereinafter referred to as “substrate” for convenience) can be formed into coatings.
Examples of the substrate include, for example, an outer plate part of an automobile body, an automobile interior base material, an outer plate part of a household electric product, cement mortar, a slate plate, a gypsum board, an extruded plate, an expandable concrete, a metal, glass, porcelain tile, Examples include asphalt, wood, waterproof rubber material, plastic, calcium silicate base material, PVC sheet, FRP (Fiber Reinforced Plastics), natural leather, synthetic leather, and fiber.
Specific examples of the coated material having a coating film obtained by applying the aqueous coating material of the present invention include, for example, interior / exterior of passenger cars / trucks / motorcycles / buses, building materials, interior / exterior of buildings, window frames, window glass, Structural members, plate materials, exteriors of machinery and equipment, dustproof covers, reflectors for road signs, gaze guidance signs, road markings, various display devices, advertising towers, sound insulation walls for roads, sound insulation walls for railways, road decorative boards, traffic lights Light source cover, outdoor display board, bridge, guardrail, tunnel interior, tunnel lighting device, glass, solar battery cover, solar water heater heat collection cover, tent, plastic house, vehicle lamp cover, road mirror, vehicle Mirrors, motorcycle weighing covers and weighing panels, glass lenses, plastic lenses, helmet shields, goggles, houses and window glass for automobiles and railway vehicles, riding Windshield, heat exchange fins, glass surfaces at various locations, blinds, tire wheels, roofing materials, housing equipment, toilets, bathtubs, washbasins, lighting fixtures, lighting covers, kitchenware, sinks, cooking ranges, kitchen hoods, Examples thereof include a ventilation fan, a ship bottom, a functional fiber, a display which is a display screen of a television or a personal computer, and a film to be attached to the article.

(Formation method of coating film)
Examples of methods for applying the aqueous coating material to the surface of various substrates include air spray coating, airless spray coating, rotary atomization coating, curtain coat coating, roller coat coating, bar coat coating, air knife coating, brush coating, Various coating methods such as dipping coating can be selected as appropriate.
The coating amount of the aqueous coating material is the thickness after drying of the coating film obtained by applying the aqueous coating material, and is usually preferably about 0.1 to 100 μm, more preferably 1 to 50 μm, An amount of 10 to 40 μm is particularly preferable.
Moreover, it is preferable that the drying temperature after application | coating is normal temperature drying (5-35 degreeC), or the range exceeding 35 degreeC and 200 degrees C or less, ie, 5-200 degreeC. In particular, the aqueous coating material of the present invention can form a coating film having excellent water resistance and solvent resistance even when the drying conditions are low temperature and short time, so that it is dried at room temperature (5-35 ° C.) or low temperature from the viewpoint of energy saving. It is preferable to employ drying (over 35 ° C. and 100 ° C. or less), that is, drying at 5 to 100 ° C., and more preferably 5 to 80 ° C. The drying time is preferably, for example, 30 seconds to 5 minutes. According to the aqueous coating material of the present invention, a coating film excellent in water resistance and solvent resistance can be formed even under conditions where water and solvent evaporation and particle fusion are insufficient.
Moreover, you may implement the drying after application | coating in two or more processes. For example, after performing a preliminary process such as preheating or air blowing, this process may be performed using a drying furnace such as a hot air furnace, an electric furnace, or an infrared induction heating furnace at a higher temperature than the preliminary process. When preheating is performed, the time is preferably about 30 seconds to 15 minutes, more preferably 1 to 10 minutes, and further preferably 2 to 5 minutes. The temperature and time of this step can be appropriately selected from the above preferable range and the like.

Furthermore, the coated product of the present invention preferably has a gloss retention of 60% or more after being immersed in solvent naphtha (CAS: 64742-95-6) for 30 seconds. By having such solvent resistance, even if the drying conditions are low temperature and for a short time, for example, even when a paint containing solvent naphtha (CAS: 64742-95-6) is overcoated, the paint is applied. A good coating film can be formed without disturbing the surface. More preferably, the gloss retention is 70% or more, and more preferably 80% or more.
Here, “gloss retention” means that the test plate for evaluation was immersed in Solvent Naphtha (CAS: 64742-95-6) for 30 seconds, and then the solvent remaining on the coating film surface was removed and dried at room temperature for 2 hours. It refers to the retention rate (%) of the subsequent 60 ° gloss. The 60 ° gloss retention rate (%) is “G1” for 60 ° gloss of the pre-test coating film, and “G2” for 60 ° gloss after being immersed in solvent naphtha for 30 seconds and dried at room temperature for 2 hours. In this case, the value is represented by “(G2 / G1) × 100”. Refers to that.
Such 60 degree gloss can be measured by Nippon Denshoku Industries Co., Ltd. PG-1M.

  As described above, according to the present invention, the polymer dispersion having excellent polymerization stability and excellent paint viscosity characteristics and storage stability when used in an aqueous coating material, and the polymer dispersion are included. Polymer particles can be provided. According to the present invention, an aqueous coating material capable of forming a coating film excellent in water resistance and solvent resistance even when the drying conditions are low temperature and for a short time, and a coated article coated with the aqueous coating material. Can be provided. Moreover, the coated material in which the coating film is formed with the aqueous coating material of the present invention can also exhibit excellent coating film appearance, solvent resistance, water resistance, water absorption resistance, and hydrolysis resistance.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated in detail, this invention is not limited to these Examples.
Unless otherwise specified, “part” in this example means “part by mass”, and “%” means “mass%”. Moreover, the measurement, evaluation, etc. about the polymer dispersion liquid and the aqueous coating material in this example were performed by the methods shown below.
In addition, Tables 1 and 2 show the measurement results, evaluation results, and the like in each example, such as the number of blended parts of each component when the polymer dispersion was produced in each example.

<Evaluation method>
(Gel fraction relative to DMF)
The polymer dispersion is applied to a polypropylene plate so that the dry film thickness is 200 μm, and dried at 23 ° C. for 24 hours to obtain a coating film. From the obtained coating film, 0.035 to 0.045 g is weighed, a sample is cut out, the weight of the sample is measured, and “weight of coating film before DMF immersion” is determined. Then, it is placed in 20 ml of DMF and immersed at 23 ° C. for 24 hours. After immersion, filter with a tetrafluoroethylene resin (PTFE) filter (product name: PF100, manufactured by ACVANTEC), dry at 105 ° C. for 3 hours, and cool, then measure “total weight of filter and residue” To do. The gel fraction is determined by substituting “weight of coating film before DMF immersion”, “weight of filter”, and “total weight of filter and residue after DMF immersion” into the following formula (1).
Gel fraction (%) = (“total weight of filter and residue after immersion in DMF” − “weight of filter”) / “weight of coating film before immersion in DMF”) × 100 (1)

(Storage stability of aqueous coating materials)
The aqueous coating material is put in a 250 ml polyethylene container, covered, and left in a thermostatic bath at 25 ° C. for 3 hours. When the temperature reaches 25 ° C., a B-type viscometer (manufactured by TOKI SANGYO Co., TV- After measuring the viscosity η1 at 6 rpm with a 10M type, # 3 rotor), it was allowed to stand in a 40 ° C. atmosphere for 10 days and then left in a 25 ° C. thermostatic bath for 3 hours. When the temperature reached 25 ° C., B The viscosity η2 at 6 rpm was measured with a mold viscometer, and the viscosity change rate was calculated from the following formula (2).
V = {(η2-η1) / η1} × 100 (2)
Here, the symbol in Formula (1) shows the following values.
V: Viscosity change rate (%)
η1: Initial viscosity (mPa · s, 6 rpm)
η2: viscosity after standing at 40 ° C. for 10 days (mPa · s, 6 rpm)
The viscosity change rate (%) obtained was evaluated according to the following criteria.
A: Viscosity change rate within ± 20% B: Viscosity change rate within ± 50%

(Water resistance and solvent resistance of coating film)
[Preparation of test plate for evaluation]
A black acrylic plate (TP Giken, 2 mm thick, 150 mm long x 70 mm wide) was coated with the aqueous coating material obtained in each example with a bar coater # 40 in an atmosphere of 20 ° C. It dried on dry conditions (80 degreeC, 3 minutes). Then, what was left to stand at room temperature for 30 minutes was used as the test plate for evaluation of solvent resistance and water resistance. The film thickness after drying of the coating film was about 20 μm.

[Evaluation of water resistance]
The test plate for evaluation was immersed in warm water at 40 ° C. for 10 days, taken out and dried at room temperature for 2 hours, and ΔL was defined as 60 ° gloss retention (gloss retention) and ΔL.
The 60% gloss retention rate (%) means that the 60 ° gloss of the pre-test coating film was taken out after being immersed in warm water of “G1” and 40 ° C. for 10 days, and the coating film 60 hours after drying at room temperature for 2 hours. When the gross is “G2”, the value is represented by “(G2 / G1) × 100”. The 60 ° gloss was measured with PG-1M manufactured by Nippon Denshoku Industries Co., Ltd.
ΔL is a value obtained by subtracting “L value of coating film before test” from “L value of coating film taken out after being immersed in warm water of 40 ° C. for 10 days and dried at room temperature for 2 hours”. The L value is an index of “brightness (whiteness)” and was measured with a CR-300 manufactured by MINOLTA.
Moreover, water resistance was evaluated based on the following criteria.
A: The retention rate of 60 ° gloss is 90% or more and the absolute value of ΔL is 0.5 or less. B: The retention rate of 60 ° gloss is 80% or more and the absolute value of ΔL is more than 0.5 and 1.5 or less.

[Evaluation of solvent resistance]
The test plate for evaluation is immersed in SOLVESSO 100 (an aromatic solvent manufactured by ExxonMobil Chemical, Solvent Naphtha (CAS: 64742-95-6)) for 30 seconds, and the solvent remaining on the coating film surface is sucked up by Kimwipe immediately after being pulled up. It was. The 60 ° gloss retention (gloss retention) and ΔL (difference in L value before and after immersion in a solvent) after drying at room temperature for 2 hours were used as indicators of solvent resistance.
The 60 ° gloss retention rate (%) means that the 60 ° gloss of the pre-test coating film is immersed in “G1” and SOLVESSO 100 for 30 seconds, and the solvent remaining on the coating film surface is sucked off by Kimwipe immediately after pulling up. When the 60 ° gloss after drying at room temperature for 2 hours is “G2”, the value is represented by “(G2 / G1) × 100”. The 60 ° gloss was measured with PG-1M manufactured by Nippon Denshoku Industries Co., Ltd.
ΔL means “the coating film before the test after being immersed in SOLVESSO 100 for 30 seconds, the solvent remaining on the surface of the coating film is absorbed by Kimwipe immediately after pulling up and dried at room temperature for 2 hours”. This is a value obtained by subtracting the “L value”. The L value is an index of “brightness (whiteness)” and was measured with a CR-300 manufactured by MINOLTA.
Moreover, solvent resistance was evaluated based on the following criteria.
A: Retention rate of 60 ° gloss is 80% or more and ΔL absolute value is 1.0 or less B: Retention rate of 60 ° gloss is 60% or more and ΔL is more than 1.0 and 1.5 or less C: 60 ° Gloss retention is less than 60% and ΔL is over 1.5

[Example 1]
(Preparation of polymer dispersion)
(1) First stage polymerization process (mixed introduction of acrylic monomer mixture)
Polyurethane resin (A) as urethane resin (A) (trade name: Implanil LP RSC 3040, manufactured by Sumika Bayer Urethane Co., Ltd.) in a flask equipped with a stirrer, reflux condenser, temperature controller, and dropping pump , Solid content 40%): 75 parts (30 parts as solid content), deionized water: 73.2 parts, Neocor SWC (anionic surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., solid content 70%): 0.4 part (solid content 0.28 part), Adeka Soap ER-10 (nonionic surfactant, manufactured by ADEKA Corporation): 0.4 part, methyl methacrylate: 5 as an acrylic monomer mixture .95 parts, normal butyl acrylate: 43.4 parts, allyl methacrylate: 0.05 parts were charged, and the flask was heated to 50 ° C. Thereafter, as a polymerization initiator, a 70% aqueous solution of t-butyl hydroperoxide (trade name; Kayabutyl H70, manufactured by Kayaku Akzo Co., Ltd.): 0.02 part (0.014 part as a pure component) and a reducing agent As follows: Ferrous sulfate: 0.00020 part, ethylenediaminetetraacetic acid (EDTA): 0.00027 part, sodium ascorbate: 0.02 part, deionized water: 1 part. Further, after confirming the peak top temperature due to the polymerization exotherm, the internal temperature of the flask was raised to 75 ° C. and held for 20 minutes.
(2) Second stage polymerization step (pre-emulsion solution added dropwise)
Next, 0.1 parts of sodium ascorbate and 5 parts of deionized water are added as a reducing agent to the dispersion obtained in the above (1) and kept at 75 ° C. for 10 minutes. 11 parts, 2-ethylhexyl acrylate: 8.1 parts, 2-hydroxyethyl methacrylate: 1.14 parts, acrylic acid: 0.36 parts, Neocor SW-C: 0.4 parts (solid content 0.28 parts), ADEKA rear soap ER-10: 0.4 part, deionized water: 16 part pre-emulsified pre-emulsified liquid and t-butyl hydroperoxide 70% aqueous solution (trade name; Kayabutyl H70, Kayaku Akzo ( Co., Ltd.): 0.03 parts (0.021 parts as a pure component), deionized water: 5 parts of a polymerization initiator aqueous solution was added dropwise over 1 hour. During the dropwise addition, the internal temperature of the flask was maintained at 75 ° C., and was maintained at 75 ° C. for 1.5 hours after the completion of the dropwise addition. Thereafter, the reaction liquid is cooled to room temperature, dimethylaminoethanol: 0.52 part and deionized water: 5 parts are added as an aqueous amine solution, and a dispersion liquid (polymer dispersion liquid) containing the polymer particles of the present invention is obtained. Obtained.
Table 1 shows the nonvolatile content and the average particle size of the obtained dispersion.
(Preparation of aqueous coating material)
In the obtained polymer dispersion, 12 parts of 2-ethyl-1-hexanol as a solvent (11.8% with respect to the solid content of the obtained polymer dispersion) and a urethane associative thickener as a thickener. (Product name: UH-756-VF, manufactured by ADEKA Co., Ltd.) 0.6 part (0.6% based on the solid content of the obtained polymer dispersion) was added and mixed to prepare an aqueous coating material. Prepared. The concentration of the polymer particles in the obtained aqueous coating material was 37.7%.
The obtained aqueous coating material was applied to a test plate for evaluation as described above to form a coating film, and the water resistance and solvent resistance of the coating film were evaluated. Moreover, the storage stability of the aqueous coating material was evaluated. The evaluation results are shown in Table 1.

[Examples 3 to 13]
As shown in Table 1, a polymer dispersion and an aqueous coating material were prepared in the same manner as in Example 1, except that each component was used. And the measurement and evaluation similar to Example 1 were performed. The evaluation results are shown in Tables 1 and 2.

[Example 2]
(Preparation of polymer dispersion)
(1) First stage polymerization process (dropping acrylic monomer mixture)
Polyurethane resin (A) as urethane resin (A) (trade name: Implanil LP RSC 3040, manufactured by Sumika Bayer Urethane Co., Ltd.) in a flask equipped with a stirrer, reflux condenser, temperature controller, and dropping pump , Solid content 40%): 75 parts (30 parts as solid content), deionized water: 68.2 parts, Neocor SWC (anionic surfactant, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., solid content 70%): 0.4 part (solid content 0.28 part), Adekaria soap ER-10 (nonionic surfactant, manufactured by ADEKA Corporation): 0.4 part charged, the flask was heated to 50 ° C., reducing agent As follows: Ferrous sulfate: 0.00020 part, ethylenediaminetetraacetic acid (EDTA): 0.00027 part, sodium ascorbate: 0.12 part, deionized water: 1 part. Thereafter, as an acrylic monomer mixture, a mixture of methyl methacrylate: 5.95 parts, normal butyl acrylate: 43.4 parts, allyl methacrylate: 0.05 parts, and a 70% aqueous solution of t-butyl hydroperoxide (product) Name: Kayabutyl H70, manufactured by Kayaku Akzo Co., Ltd.): 0.032 parts (0.0224 parts as a pure component), deionized water: 10 parts, a polymerization initiator aqueous solution was added dropwise over 1 hour 45 minutes. . During the dropping, the internal temperature of the flask was kept at 50 ° C., and after the dropping was finished, the temperature was raised to 75 ° C. and kept for 20 minutes.
(2) Second stage polymerization step (pre-emulsion solution added dropwise)
Subsequently, to the dispersion obtained in (1) above, methyl methacrylate: 11 parts, 2-ethylhexyl acrylate: 8.1 parts, 2-hydroxyethyl methacrylate: 1.14 parts, acrylic acid: 0.36 parts, neocol SW-C: 0.4 part (solid content 0.28 part), Adequalia soap ER-10: 0.4 part, deionized water: pre-emulsified dispersion containing 16 parts, and t-butyl A polymerization initiator aqueous solution containing a hydroperoxide 70% aqueous solution (trade name; Kayabutyl H70, manufactured by Kayaku Akzo Co., Ltd.): 0.018 parts (0.0126 parts as a pure component) and deionized water: 5 parts. The solution was added dropwise over 1 hour. During the dropwise addition, the internal temperature of the flask was maintained at 75 ° C., and was maintained at 75 ° C. for 1.5 hours after the completion of the dropwise addition. Thereafter, the reaction liquid is cooled to room temperature, dimethylaminoethanol: 0.52 part and deionized water: 5 parts are added as an aqueous amine solution, and a dispersion liquid (polymer dispersion liquid) containing the polymer particles of the present invention is obtained. Obtained.
Table 1 shows the nonvolatile content and the average particle size of the obtained dispersion.
The aqueous coating material was prepared in the same manner as in Example 1. And the measurement and evaluation similar to Example 1 were performed. The evaluation results are shown in Table 1.

[Comparative Examples 1 and 2]
As shown in Table 2, a polymer dispersion and an aqueous coating material were prepared in the same manner as in Example 1 except that each component was used. And the measurement and evaluation similar to Example 1 were performed. The evaluation results are shown in Table 2.

However, the symbol in a table | surface shows the following compounds.
[Urethane resin (A)]
I-1: Polyester urethane resin having a sulfonic acid group (A) (trade name: Implanil LP RSC 3040, manufactured by Sumika Bayer Urethane Co., Ltd., solid content 40%)
I-2: Polycarbonate urethane resin having a sulfonic acid group (A) (trade name: F-8082D, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., solid content: 41%)
[Acrylic monomer mixture]
(Monomer having one radically polymerizable group)
MMA: methyl methacrylate nBA: normal butyl acrylate 2EHA: 2-ethylhexyl acrylate (monomer having two or more radically polymerizable groups)
AMA: allyl methacrylate TAC: triallyl cyanurate EDMA: ethylene dimethacrylate (hydroxyl group-containing radical polymerizable monomer)
2HEMA: 2-hydroxyethyl methacrylate (acid group-containing radical polymerizable monomer)
・ AA: Acrylic acid

As shown in Tables 1 and 2, the polymer dispersions of Examples 1 to 13 were excellent in polymerization stability and excellent in storage stability of an aqueous coating material obtained from the dispersion. Furthermore, the coating film obtained from the aqueous coating material had excellent water resistance and solvent resistance even under low temperature and short drying conditions of 80 ° C. for 3 minutes.
On the other hand, as shown in Table 2, in Comparative Examples 1 and 2, since the gel fraction with respect to DMF is less than 10%, dissolution or swelling of the coating film was recognized in the evaluation of the solvent resistance of the coating film. The solvent resistance was poor.

  The polymer dispersion of the present invention is excellent in polymerization stability during production, and the aqueous coating material containing the polymer dispersion is excellent in paint viscosity characteristics and storage stability. Furthermore, the coating film to which the aqueous coating material of the present invention is applied exhibits excellent water resistance and solvent resistance. In particular, even a dried coating film obtained under conditions where the drying conditions are insufficient such as low temperature and short time evaporation of water and solvent and particle fusion are excellent in water resistance and solvent resistance. Therefore, the water-based coating material of the present invention is applied to various coatings such as outer plate parts of automobile bodies such as passenger cars, trucks, motorcycles, buses, etc., protection of chassis of automobile parts, buildings, civil engineering structures, etc. It can be used for applications and is extremely useful industrially.

Claims (7)

Polymer particles containing urethane resin (A) and acrylic polymer (B) in the same particle, and the gel fraction measured in N, N′-dimethylformamide (DMF) of the polymer particle is 10% or more ,
The acrylic polymer (B) includes a monomer unit derived from an acid group-containing radical polymerizable monomer,
The ratio of the monomer unit derived from the acid group-containing radical polymerizable monomer is 0.008 to 3.4% by mass with respect to the total mass of the urethane resin (A) and the acrylic polymer (B). Polymer particles.   The polymer particle according to claim 1, wherein the urethane resin (A) is a urethane resin having a sulfonic acid group.   The acrylic polymer (B) contains a monomer unit derived from a monomer having two or more radically polymerizable groups, and a ratio of monomer units derived from a monomer having two or more radically polymerizable groups The polymer particles according to claim 1, wherein the content is 0.01 to 10% by mass relative to the total mass of the urethane resin (A) and the acrylic polymer (B). The polymer dispersion liquid containing the polymer particle as described in any one of Claims 1-3 . An aqueous coating material comprising the polymer dispersion according to claim 4 . A coated article to which the aqueous coating material according to claim 5 is applied. The coated article according to claim 6 , wherein the gloss retention of the coating film after being immersed in solvent naphtha for 30 seconds is 60% or more.