JP2009270034A - Water-based resin composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a water-based resin composition, wherein an amount of a film forming aid is reduced, and a coating film excellent in weatherability and antiblocking property under more severe conditions is formed. <P>SOLUTION: The water-based resin composition is used for an enamel coating material and contains a water-based resin dispersion and a crosslinking agent as essential components. An alkoxysilane group-containing polymerizable monomer (A) and a cycloalkyl group-containing polymerizable monomer (B), are contained as high Tg components of a core-shell type water-based resin dispersion. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an aqueous resin composition that can be used for paints, coating applications, and the like, which can reduce film forming aids and is excellent in weather resistance, blocking resistance, and film flexibility. (Blocking refers to the phenomenon in which coating films adhere to each other when various materials to be coated, such as metal, wood, paper, plastic, and inorganic building materials coated with acrylic emulsion, are stacked. Sure.)

  In recent years, water-based paints are increasingly used from the viewpoint of environmental problems, and water-based resin dispersions are widely used for paints and coating applications. However, since film formation (film formation) of an aqueous resin dispersion is performed by fusing polymer particles, a film having a high glass transition temperature (Tg) must be formed using a large amount of a film forming aid. . Therefore, when the coating film is insufficiently dried, there is a problem that the blocking resistance is deteriorated due to the influence of the remaining film-forming auxiliary. Moreover, although the thing with low glass transition temperature (Tg) of an aqueous resin dispersion can be formed into a film near normal temperature, the formed coating film remains adhesive after drying, and there exists a problem that blocking resistance worsens. is there. Dispersion of water-based resin used for factory coating, etc., because the coating resistance and the base material are destroyed when the blocking resistance is poor, and the purpose of the coating, which is the original purpose of coating, is not achieved. The body needs blocking resistance. Therefore, a monomer having a high Tg component was used for the core portion having a low film formation temperature (MFT) that requires a high Tg and less film-forming aid, and a monomer having a low Tg component was used for the shell portion. A hardcore / soft shell type aqueous resin dispersion has been proposed. However, the required level of blocking resistance has been further increased by shortening the drying time and increasing the product load for the purpose of improving production in factory coating. In response to such demands, the blocking resistance exhibited by the hard core / soft shell type aqueous resin dispersion is insufficient.

For this reason, various studies have been conducted on aqueous resin compositions comprising an aqueous resin dispersion and a crosslinking agent, which are disclosed in Patent Documents 1, 2, and 3. However, in Patent Document 1, since the silicone is not modified, the weather resistance is insufficient. In Patent Document 2, there is a problem in weather resistance, and since an ethylenically unsaturated monomer having a polyethylene glycol chain or a polypropylene glycol chain is used, the water resistance is insufficient. In Patent Document 3, an aqueous resin dispersion excellent in weather resistance and blocking resistance, an organic hydrazine compound having at least two hydrazino groups in the molecule, and a semicarbazide curing agent are blended. Although bodies have been proposed, all of them have insufficient blocking resistance under more severe conditions.
Japanese Patent Laying-Open No. 2005-8862 JP 2004-83644 A JP 2008-56751 A

  This invention is providing the water-based resin composition which can form the coating film which can reduce the film-forming auxiliary | assistance and was excellent in the weather resistance and the blocking resistance under severer conditions.

As a result of intensive studies to solve the above problems, the present inventors have completed the present invention.
That is, the first of the present invention is an aqueous resin composition for enamel paint, which contains an aqueous resin dispersion and a crosslinking agent as essential components.
A second aspect of the invention is characterized in that the high-Tg resin component of the aqueous resin dispersion contains an alkoxysilane group-containing polymerizable monomer (A) and a cycloalkyl group-containing polymerizable monomer (B). It is the aqueous resin composition of 1st invention.
A third aspect of the present invention is the aqueous resin composition according to any one of the first and second aspects, wherein no reactive emulsifier is used as the high Tg resin component of the aqueous resin dispersion.
A fourth aspect of the invention is an aqueous resin dispersion obtained by polymerizing an aqueous resin dispersion using two or more kinds of polymerizable monomers having different glass transition temperatures (Tg). The body is composed of a high Tg component having a glass transition temperature (Tg) of 50 ° C. or more and a low Tg component having a glass transition temperature (Tg) of 40 ° C. or less, and the ratio of the high Tg component to the low Tg component is high Tg component / The aqueous resin composition according to any one of the first to third inventions, wherein the low Tg component (weight ratio) is 46/54 to 70/30.
A fifth aspect of the invention includes any one of the first to fourth aspects, including a carboxyl group-containing polymerizable monomer and a hydroxyl group-containing polymerizable monomer as a low Tg resin component of the aqueous resin dispersion. This is an aqueous resin composition of the invention.
In a sixth aspect of the invention, the crosslinking agent is at least one selected from a compound having an isocyanate group, a compound having an aziridine ring, a compound having an oxazoline ring, and a compound having a carbodiimide group, and the blending amount thereof is aqueous. The aqueous resin composition according to any one of the first to fifth inventions, wherein the amount is 0.1 to 2 equivalents relative to the functional group of the resin dispersion.
A seventh aspect of the invention is the aqueous resin composition according to any one of the first to sixth aspects, wherein the aqueous resin dispersion also contains a Si-containing compound represented by the following formula (1): is there.
_{^{(R 1) n -Si- (R}} 2) 4-n (1)
(In the formula, n is an integer of 0 to 3, and R ¹ is selected from hydrogen, an aliphatic hydrocarbon group having ^{1 to} 16 carbon atoms, an aryl group having 5 to 10 carbon atoms, and a cycloalkyl group having 5 to 6 carbon atoms. N R ¹ may be the same or different, and R ² is selected from an alkoxy group having 1 to 8 carbon atoms, an acetoxy group, and a hydroxyl group, and 4-n R ² is the same. Or it may be different.)
The eighth aspect of the invention is characterized in that the amount of the polymerizable monomer used to obtain the aqueous resin dispersion exceeds 50%, and the solubility of water at 20 ° C. is 0.1% by mass or more. The aqueous resin composition according to any one of the first to seventh inventions.
A ninth aspect of the invention is any one of the first to eighth aspects, wherein the polymerizable monomer of the low Tg resin component of the aqueous resin dispersion contains 5% by mass or more of methyl methacrylate and cyclohexyl methacrylate, respectively. It is the aqueous resin composition of the invention.
The tenth aspect of the invention is that the high Tg resin component of the aqueous resin dispersion is composed of the central portion (core) of the aqueous resin dispersion particles, and the low Tg resin component of the aqueous resin dispersion is the outer portion (shell) of the aqueous resin dispersion particles. The aqueous resin composition according to any one of the first to ninth inventions, wherein the aqueous resin composition has a structure comprising:
The eleventh aspect of the invention is the aqueous resin composition according to any one of the first to tenth aspects, wherein the aqueous resin composition is obtained by emulsion polymerization in two or more steps.
A twelfth aspect of the present invention is the aqueous resin composition according to the first aspect of the present invention, which is produced at a pH of 4 or less during emulsion polymerization.

  If the aqueous resin composition of this invention is used, the coating film which is excellent in a weather resistance and blocking resistance can be formed.

  Hereinafter, the present invention will be described in detail.

Aqueous Resin Dispersion Examples of the aqueous resin dispersion used in the present invention include acrylic emulsions, urethane emulsions, and fluorine emulsions. In the present invention, acrylic emulsions are preferred. Acrylic emulsions are less expensive than urethane emulsions, and even when used alone, they have good stain resistance. Acrylic emulsions are cheaper than fluorine emulsions, and have good recoatability and stain resistance.

Alkoxysilane group-containing polymerizable monomer Examples of the alkoxysilane group-containing polymerizable monomer used in the present invention include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (β-methoxyethoxy) silane, and vinylmethyldimethoxysilane. , Γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-methacryloxy Examples thereof include propyltriethoxysilane and γ-methacryloxypropylmethyldiethoxysilane, and one or more selected from these groups are used. Particularly preferred are γ-methacryloxypropyltrimethoxysilane and γ-methacryloxypropyltriethoxysilane. Furthermore, it is important to use an alkoxysilane group-containing polymerizable monomer in an amount of 0.1 to 10% by mass based on the total polymerizable monomer used to obtain the aqueous resin dispersion. In particular, 0.1 to 5% by mass is preferable from the viewpoints of polymerization stability, water resistance and blocking resistance.

Cycloalkyl group-containing polymerizable monomer Examples of the cycloalkyl group-containing polymerizable monomer used in the present invention include cyclohexyl (meth) acrylate, methylcyclohexyl (meth) acrylate, and tertiary butylcyclohexyl (meth) acrylate. 1 or 2 or more selected from these groups is used. Particularly preferred is cyclohexyl (meth) acrylate. Furthermore, it is important to use a cycloalkyl group-containing polymerizable monomer in an amount of 5 to 45% of the entire polymerizable monomer used for obtaining the aqueous resin dispersion. When the ratio in the polymerizable monomer is less than 5%, the weather resistance is poor. Moreover, when the said ratio in a polymerizable monomer exceeds 45%, superposition | polymerization stability will worsen. In particular, 10% to 40% is preferable from the viewpoints of polymerization stability, weather resistance, and blocking resistance.

Reactive emulsifier The reactive emulsifier referred to in the present invention is an emulsifier having an unsaturated double bond in the molecule, and examples thereof include an anionic emulsifier and a nonionic emulsifier. For example, fatty acid salts such as sodium lauryl sulfate, higher alcohol sulfate esters, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether sulfates, polyoxyethylene polycyclic phenyl ether sulfates, polyoxynonyls Phenyl ether sulfonate, polyoxyethylene-polyoxypropylene glycol ether sulfate, reactive anionic emulsifier having a sulfonic acid group or sulfate ester group and a polymerizable unsaturated double bond in the molecule, or the aforementioned skeleton Examples thereof include a reactive nonionic emulsifier having a polymerizable unsaturated double bond in the molecule. It is important that these reactive emulsifiers are not used in the high Tg resin component of the aqueous resin dispersion. When these reactive emulsifiers are used in the high Tg resin component of the aqueous resin dispersion, the film formability of the aqueous resin dispersion is lowered, and the target minimum film formation temperature (MFT) cannot be obtained. These reactive emulsifiers may be used for the low Tg resin component of the aqueous resin dispersion.

Aqueous resin dispersion The aqueous resin dispersion in the present invention is an aqueous resin dispersion formed by integrating a plurality of polymerizable monomer components having different glass transition temperatures (Tg) in the course of polymerization, and has a high Tg. It is an acrylic polymer in which the Tg of the resin component is 50 ° C. or higher and the Tg of the low Tg resin component is 40 ° C. or lower. In particular, the high Tg resin component is in the core portion and the low Tg resin component is in the shell portion due to blocking resistance and film formability. The above is preferable. In the present invention, the Tg (K: absolute temperature) of the aqueous resin dispersion is calculated using the following FOX equation.
1 / Tg = W ₁ / Tg ₁ + W ₂ / Tg ₂ +... + W _i / Tg _i +... W _n / Tg _n
[In the FOX formula, the glass transition temperature of the homopolymer of each monomer constituting the polymer composed of n types of monomers is Tg _i (K), the weight fraction of each monomer is W _i , (W ₁ + W ₂ +... + W _i +... + W _n = 1)]
Furthermore, in the present invention, it is important that the ratio of the high Tg resin component and the low Tg resin component is high Tg resin component / low Tg resin component (weight ratio) = 46/54 to 70/30. Preferably, high Tg resin component / low Tg resin component (weight ratio) = 50/50 to 60/40. When the ratio of the high Tg resin component is less than the above ratio, the blocking resistance is deteriorated. On the other hand, when the ratio of the high Tg resin component is larger than the above range, the MFT rises and the frost damage resistance is impaired.
SPM (scanning probe microscope) can be used as a method for confirming that the above-described high Tg resin component is in the core portion and the low Tg resin component is in the shell portion.

Carboxyl group-containing polymerizable monomer Specific examples of the carboxyl group-containing polymerizable monomer used in the present invention include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, maleic anhydride, and the like. One or more selected from these counties are used. Acrylic acid and methacrylic acid are particularly preferred. Furthermore, it is important to use a carboxyl group-containing polymerizable monomer in an amount of 0.5 to 10% of the entire polymerizable monomer used for obtaining the aqueous resin dispersion. In particular, 1 to 5% is preferable from the viewpoint of blocking resistance and adhesion to the base.

Hydroxyl group-containing polymerizable monomer Specific examples of the hydroxyl group-containing polymerizable monomer used in the present invention include 2-hydroxyethyl (meth) acrylate, 4-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl. Examples thereof include (meth) acrylate, caprolactone-modified (meth) acrylate, polyethylene glycol (meth) acrylate, polypropylene glycol (meth) acrylate, and one or more selected from these groups are used. Particularly preferred is 2-hydroxyethyl (meth) acrylate. From the viewpoint of water resistance and color developability, it is important to use 0.1 to 5% of the entire polymerizable monomer used to obtain one or more of these aqueous resin dispersions.

Crosslinking agent Examples of the crosslinking agent used in the present invention include a compound having an isocyanate group, a compound having an aziridine ring, a compound having an oxazoline ring, and a compound having a carbodiimide group.

Compound having an isocyanate group The compound having an isocyanate group used in the present invention is not particularly limited as long as it has two or more isocyanate groups in the molecule, but 1,6-hexamethylene diisocyanate, tolylene diisocyanate. , Diphenylmethane diisocyanate, xylylene diisocyanate, isophorone diisocyanate, metaxylylene diisocyanate, 4,4′-methylenebis (cyclohexyl isocyanate), and adducts such as trimethylolpropane adducts, burettes, isocyanurates, etc. which are derivatives of these diisocyanates Polyisocyanate compounds, those obtained by homopolymerizing the above isocyanate group-containing polymerizable monomers by known polymerization methods, or other polymerizable monomers. Such as was engaged, or can use these emulsion.
As the compound having an isocyanate group used in the present invention, a water-dispersible polyisocyanate compound modified with a nonionic and / or ionic surfactant is suitable from the viewpoint of water-dispersibility. . As such a polyisocyanate compound, any compound obtained by introducing a hydrophilic group by a conventionally known method can be used without particular limitation. For example, a reaction product of an alkoxy polyalkylene glycol and a polyisocyanate compound, a surface active ability Reaction product of vinyl polymer containing nonionic group and isocyanate-reactive group (hydroxyl group, etc.) having polyisocyanate and polyisocyanate compound, reaction product obtained by reacting dialkanolamine, isethionate amine salt Examples thereof include a polyisocyanate compound containing a reaction product of a compound having a sulfonic acid group and an isocyanate reactive group and a polyisocyanate compound. Among these, a polyisocyanate compound containing a reaction product of an alkoxy polyalkylene glycol and a polyisocyanate compound is particularly preferable because of its excellent water dispersibility. Examples of such a commercially available product include trade names “Duranate WT20-100”, “Duranate WT30-100”, “Duranate WT40-100” (manufactured by Asahi Kasei Chemicals Corporation) and the like.

Compound having an aziridine ring As the compound having an aziridine ring used in the present invention, an aziridinyl group-containing ethylenically unsaturated monomer such as (meth) acrylic acid-2-aridinylethyl is homopolymerized using a known polymerization method. Or those copolymerized with other unsaturated monomers can be used. Examples of commercially available products include “Chemite PZ-33” and “Chemite DZ-22E” (manufactured by Nippon Shokubai Co., Ltd.).

Compounds having an oxazoline ring As compounds having an oxazoline ring used in the present invention, known oxazoline group-containing ethylenically unsaturated monomers such as 2-isopropenyl-2-oxazoline and 2-vinyl-2-oxazoline are known. Those obtained by homopolymerization using a polymerization method or those copolymerized with other vinyl monomers can be used. Commercially available products include “Epocross WS-500” and “Epocross WS-700”. ”,“ Epocross K-2010E ”,“ Epocross E-2020E ”,“ Epocross E-2030E ”(manufactured by Nippon Shokubai Co., Ltd.), and the like.

Compounds having a carbodiimide group In the present invention, various compounds having a carbodiimide group are known. For example, they are obtained by the production methods described in JP-A-6-56950, JP-A-9-77839 and the like. Examples of commercially available products include “Carbodilite SV-02”, “Carbodilite V-02”, “Carbodilite V-02-L2”, “Carbodilite V-04”, “Carbodilite E-”. 01 "," Carbodilite E-02 "(manufactured by Nisshinbo Industries, Inc.) and the like.
One or more of these crosslinking agents can be appropriately selected and used as necessary. Furthermore, it is preferable that the compounding quantity is 0.1-2 equivalent with respect to the functional group of an aqueous resin dispersion from the viewpoint of the softness | flexibility of a coating film, and water resistance. In addition, a catalyst can also be used in order to enhance the reaction between the functional group of the aqueous resin dispersion and the crosslinking agent.

（式中、Ｒ^１は水素、炭素数１〜１６の脂肪族炭化水素基、炭素数５〜１０のアリール基、炭素数５〜６のシクロアルキル基、炭素数１〜１０のアクリル酸アルキル基又は炭素数１〜１０のメタクリル酸アルキル基から選ばれ、各Ｒ^２はそれぞれ、独立して炭素数１〜８のアルコキシ基、アセトキシ基、水酸基、エポキシ基、アルキレンオキサイド基又はポリアルキレンオキサイド基から選ばれ、ｍは１〜９９９の正の整数を表す。）
シラン（ＩＩＩ）またはシラン（ＩＶ）において、Ｒ^１としてはメチル基、フェニル基が特に好ましく、Ｒ^２としてはメトキシ基、エトキシ基、プロポキシ基、ブトキシ基、メトキシエトキシ基、水酸基が特に好ましい。
Ｓｉ含有化合物（Ｅ）は、シラン（ＩＩ）および、環状シラン、シラン（ＩＩＩ）、線状シロキサン、アルコキシシランオリゴマー、シラン（ＩＶ）からなる群から選ばれる少なくとも１種に加え、クロロシラン、例えばメチルクロロシラン、メチルジクロロシラン、ジメチルジクロロシラン、トリメチルクロロシラン、フェニルトリクロロシラン、ジフェニルクロロシラン、を含むことができる。 Si-containing compound The Si-containing compound used in the present invention is represented by the following formula (1).
_{^{(R 1) n -Si- (R}} 2) 4-n (1)
(In the formula, n is an integer of 0 to 3, and R ¹ is selected from hydrogen, an aliphatic hydrocarbon group having ^{1 to} 16 carbon atoms, an aryl group having 5 to 10 carbon atoms, and a cycloalkyl group having 5 to 6 carbon atoms. N R ¹ may be the same or different, and R ² is selected from an alkoxy group having 1 to 8 carbon atoms, an acetoxy group, and a hydroxyl group, and 4-n R ² is the same. Or it may be different.)
The Si-containing compound (E) preferably contains at least one of silane (I) in which n = 0 in formula (1) and / or silane (II) in which n = 1, and has good water In order to obtain the polymerization stability of the dispersion, n = 1 silane (II) is more preferable.
R ² of silane (I) is preferably each independently a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methoxyethoxy group, or a hydroxyl group. Preferable specific examples of silane (I) include tetramethoxysilane and tetraethoxysilane.
R ¹ of silane (II) is preferably a methyl group or a phenyl group, and R ² is independently preferably a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methoxyethoxy group or a hydroxyl group. Preferable specific examples of silane (II) include methyltrimethoxysilane, phenyltrimethoxysilane, methyltriethoxysilane, phenyltriethoxysilane, isobutyltrimethoxysilane and the like.
When flexibility is required, the Si-containing compound may be at least one selected from the group consisting of cyclic silane and silane (III) obtained by setting n = 2 in formula (b). preferable. This is because, by using at least one selected from the group consisting of silane (II), cyclic silane and silane (III), the crosslinking density of the silicone polymer formed by the Si-containing compound (E) is reduced, This is because the structure of the coalescence can be prevented from becoming complicated, and thereby, flexibility can be imparted to the coating film provided from the aqueous resin dispersion, particularly when used in combination with silane (II). preferable.
Specific examples of the cyclic silane include octamethylcyclotetrasiloxane, octaphenylcyclosiloxane, hexamethylcyclotrisiloxane, decamethylcyclopentasiloxane, and the like.
Specific examples of silane (III) include dimethyldimethoxysilane, diphenyldimethoxysilane, dimethyldiethoxysilane, diphenyldiethoxysilane, and methylphenyldimethoxysilane.
Further, the Si-containing compound may include at least one selected from the group consisting of linear siloxane having a hydrolyzable group, an alkoxysilane oligomer, and silane (IV) obtained by setting n = 3 in formula (1). good.
Specific examples of silane (IV) include triphenylethoxysilane and trimethylmethoxysilane.
Examples of the linear siloxane having a hydrolyzable group include compounds represented by the following general formulas (1), (2), and (3).

(In the formula, R ¹ is hydrogen, an aliphatic hydrocarbon group having ^{1 to} 16 carbon atoms, an aryl group having 5 to 10 carbon atoms, a cycloalkyl group having 5 to 6 carbon atoms, and an alkyl acrylate group having 1 to 10 carbon atoms. Or selected from alkyl methacrylate having 1 to 10 carbon atoms, and each R ² is independently selected from an alkoxy group having 1 to 8 carbon atoms, an acetoxy group, a hydroxyl group, an epoxy group, an alkylene oxide group, or a polyalkylene oxide group. And m represents a positive integer of 1 to 999.)
In silane (III) or silane (IV), R ¹ is particularly preferably a methyl group or a phenyl group, and R ² is particularly preferably a methoxy group, an ethoxy group, a propoxy group, a butoxy group, a methoxyethoxy group or a hydroxyl group.
The Si-containing compound (E) is added to at least one selected from the group consisting of silane (II) and cyclic silane, silane (III), linear siloxane, alkoxysilane oligomer, silane (IV), and chlorosilane such as methyl It may include chlorosilane, methyldichlorosilane, dimethyldichlorosilane, trimethylchlorosilane, phenyltrichlorosilane, diphenylchlorosilane.

The Si-containing compound used in the present invention can improve the gloss retention in a long-term exposure of the coating film obtained from the aqueous resin composition of the present invention outdoors. The presence of the above-mentioned silane condensate can be known by ²⁹ SiNMR ( ²⁹ Si nuclear magnetic resonance spectrum) or ¹ HNMR (proton nuclear magnetic resonance spectrum). For example, a condensate of silane (II) can be identified by ²⁹ SiNMR chemical shift showing a peak at −40 to −80 PPM.

  Polymerizable monomer other than alkoxysilane group-containing monomer, cycloalkyl group-containing monomer, carboxyl group-containing polymerizable monomer, hydroxyl group-containing polymerizable monomer, Si-containing compound used in the present invention There is no particular limitation, for example, (meth) acrylic acid esters, aromatic monomers such as styrene and vinyl toluene, vinyl esters such as vinyl acetate, vinyl propionate and vinyl persuccinate, and cyan such as (meth) acrylonitrile. Vinyl halides, vinyl halides such as vinyl chloride and vinylidene chloride, butadiene, etc., and various functional monomers such as (meth) acrylamide, diacetone acrylamide, vinylpyrrolidone, glycidyl (meth) acrylate, N-methylolacrylamide, N-butoxymethylacrylamide, divinyl Benzene, and the like methyl vinyl ketone.

  Specific examples of (meth) acrylic acid esters include (meth) acrylic acid alkyl esters having 1 to 18 carbon atoms in the alkyl moiety, and (poly) oxyethylene mono (meth) having 1 to 100 ethylene oxide groups. Acrylate, (poly) oxypropylene mono (meth) acrylate, (meth) acrylic acid hydroxyalkyl ester having 1 to 18 carbon atoms in the alkyl portion, and (poly) oxyethylene di (1) having 1 to 100 ethylene oxide groups And (meth) acrylate. Specific examples of the (meth) acrylic acid alkyl ester include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and (meth) acrylic acid t-. Examples include butyl, 2-ethylhexyl (meth) acrylate, dodecyl (meth) acrylate, and (meth) acrylic acid cycloalkyl ester.

  In the present invention, it is important that the amount exceeding 50% of the entire polymerizable monomer used to obtain the aqueous resin dispersion has a water solubility of 0.1% by mass or more at 20 ° C. Examples of the polymerizable monomer having a water solubility at 20 ° C. of 0.1% by mass or more include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, methyl methacrylate, ethyl methacrylate, acrylic acid, Examples thereof include, but are not limited to, methacrylic acid and itaconic acid. When the ratio in the polymerizable monomer is less than 50%, the minimum film-forming temperature (MFT) increases and the blocking resistance also deteriorates.

  In the present invention, it is important that the amount of methyl methacrylate and cyclohexyl methacrylate used in the low Tg component polymerizable monomer is 5% by mass or more. When the said ratio in a low Tg component will be less than 5%, respectively, enamel gloss is low and it is unsatisfactory.

  As a method for producing the aqueous resin dispersion of the present invention, an ordinary multistage emulsion polymerization method can be employed. As a typical example, an unsaturated monomer is usually emulsion-polymerized in water at a temperature of 60 to 90 ° C. in the presence of an emulsifier and a polymerization initiator in water in a state where the pH is 4 or less. Is a method in which is repeated a plurality of times. The emulsifier is not particularly limited, and for example, an anionic emulsifier, a nonionic emulsifier, a cationic emulsifier, an amphoteric emulsifier, a polymer emulsifier, and the like can be used. For example, fatty acid salts such as sodium lauryl sulfate, higher alcohol sulfate esters, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, polyoxyethylene alkyl ether sulfates, polyoxyethylene polycyclic phenyl ether sulfates, polyoxynonyls Anionic surface activity such as so-called reactive emulsifier having phenyl ether sulfonate, polyoxyethylene-polyoxypropylene glycol ether sulfate, sulfonic acid group or sulfate ester group and polymerizable unsaturated double bond in the molecule Agent: Polyoxyethylene alkyl ether, polyoxyethylene nonylphenyl ether, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene-polyoxypropylene block copolymer Or a nonionic surfactant such as a reactive nonionic surfactant having a skeleton and a polymerizable unsaturated double bond in the molecule; a cationic surfactant such as an alkylamine salt or a quaternary ammonium salt ; (Modified) polyvinyl alcohol and the like.

  Although the usage-amount of the said emulsifier is not specifically limited, For example, Preferably it is 1.0-5.0 mass% with respect to the total usage-amount of all the polymerizable monomer components. When the amount of the emulsifier used is increased, the polymerization stability is improved, and when it is decreased, the water resistance can be improved. In order to make the high Tg resin component the core and the low Tg resin component the shell, no reactive emulsifier is used for the high Tg resin component. In addition, with respect to the amount of emulsifier used in each stage, it is preferable that the amount used in the stage for producing the high Tg resin component is larger than the amount used in the stage for producing the low Tg resin component.

  The polymerization method for emulsion polymerization of the aqueous resin dispersion of the present invention includes a monomer batch charging method in which monomers are charged in a batch, a monomer dropping method in which monomers are continuously dropped, and a single amount. Examples include a pre-emulsion method in which a body, water, and an emulsifier are mixed and emulsified in advance, and these are added dropwise, or a combination thereof. At this time, the method of using the polymerization initiator is not particularly limited. In addition, the Si-containing compound may be used by simultaneously carrying out the condensation reaction of the hydrolyzable silane and the radical polymerization of the unsaturated monomer and / or preceded by the condensation reaction of the hydrolyzable silane. An emulsion polymerization method in which radical polymerization is allowed to proceed or a method in which a condensation reaction of hydrolyzable silane is allowed to proceed after the radical polymerization of an unsaturated monomer is allowed to proceed.

  The polymerization initiator used for emulsion polymerization of the aqueous resin dispersion of the present invention is a generally used radical initiator. Radical polymerization initiators generate radicals by heat or reducing substances to cause addition polymerization of polymerizable monomers, and include water-soluble or oil-soluble persulfates, peroxides, and azobis compounds. . Specifically, potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, 2,2-azobisisobutyronitrile, 2,2-azobis ( 2-diaminopropane) hydrochloride, 2,2-azobis (2,4-dimethylvaleronitrile), and the like, preferably water-soluble. When acceleration of the polymerization rate or a low temperature reaction is desired, a reducing agent such as sodium bisulfite, ferrous chloride, ascorbic acid, formaldehyde sulfooxylate salt or the like can be used in combination with the radical polymerization initiator.

  A molecular weight modifier can be used in the emulsion polymerization as required. Specific examples include dodecyl mercaptan and butyl mercaptan. The method of use is not particularly limited, but it is preferably used in the shell part, and the amount is preferably 2% or less of the total monomer amount.

  In order to maintain long-term dispersion stability of the emulsion, the aqueous resin dispersion of the present invention is a basic substance such as basic organic compounds such as amines such as ammonia and dimethylaminoethanol, sodium hydroxide, potassium hydroxide. It is preferable to adjust the pH within a range of 5 to 10 using a basic inorganic compound such as an alkali metal salt.

  In emulsion polymerization using the Si-containing compound of the present invention, after completion of emulsion polymerization, for example, dibutyltin dilaurate, dioctyltin dilaurate, dibutyltin diacetate, tin octylate, tin laurate, octylic acid can be used as a curing catalyst during film formation. Metal salts of organic acids such as iron, lead octylate, and tetrabutyl titanate, and amine compounds such as n-hexylamine and 1,8-diazabicyclo [5,4,0] -7-undecene can be added. When these curing catalysts are not water-soluble, it is desirable to emulsify with a surfactant and water when using them.

  In the present invention, by combining the aqueous resin dispersion and the crosslinking agent, the film forming aid can be reduced, and the aqueous resin composition used for paints and coating applications having excellent weather resistance, blocking resistance, and flexibility of the coating film. You can get things.

  In addition, in the aqueous resin composition of the present invention, in addition to the crosslinking agent, components that are usually added and blended with water-based paints, such as thickeners, film-forming aids, plasticizers, antifreezing agents, antifoaming agents, dyes, An antiseptic, an ultraviolet absorber, a light stabilizer and the like can be arbitrarily blended.

Specific examples of thickeners include polyvinyl alcohol (including partially saponified polyvinyl acetate), polymer dispersion stabilizers such as methylcellulose, hydroxyethylcellulose, and polyvinylpyrrolidone, and other polyether-based and polycarboxylic acid-based thickeners. Etc.
Specific examples of film forming aids include diethylene glycol monobutyl ether, ethylene glycol monobutyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, ethylene glycol mono 2-ethylhexyl ether, 2,2,4-trimethyl-1,3-butanediol iso Examples include butyrate, diisopropyl glutarate, propylene glycol n-butyl ether, dipropylene glycol n-butyl ether, tripropylene glycol n-butyl ether, dipropylene glycol methyl ether, and tripropylene glycol methyl ether. These film-forming aids can be arbitrarily blended alone or in combination.

Specific examples of the plasticizer include dibutyl phthalate and dioctyl phthalate.
Specific examples of the antifreezing agent include propylene glycol and ethylene glycol.

  There are benzophenone series, benzotriazole series, and triazine series as ultraviolet absorbers. Specific examples of benzophenone ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4- Methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, bis (5-benzoyl-4- Hydroxy-2-methoxyphenyl) methane, 2,2′-dihydroxy-4-methoxybenzophenone, 2,2′-dihydroxy-4,4′dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 4 -Dodecyloxy- - hydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxy benzophenone, and the like 2-hydroxy-4-stearyloxy benzophenone.

  Specific examples of radical polymerizable benzophenone-based UV absorbers include 2-hydroxy-4-acryloxybenzophenone, 2-hydroxy-4-methacryloxybenzophenone, 2-hydroxy-5-acryloxybenzophenone, and 2-hydroxy-5. -Methacryloxybenzophenone, 2-hydroxy-4- (acryloxy-ethoxy) benzophenone, 2-hydroxy-4- (methacryloxy-ethoxy) benzophenone, 2-hydroxy-4- (methacryloxy-diethoxy) benzophenone, 2-hydroxy-4- (Acryloxy-triethoxy) benzophenone.

  Specific examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole, 2- (2-hydroxy-3,5- Di-tert-octylphenyl) benzotriazole, 2- [2′-hydroxy-3 ′, 5′-bis (α, α′-dimethylbenzyl) phenyl] benzotriazole), methyl-3- [3-tert-butyl -5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl] propionate and polyethylene Condensate with glycol (molecular weight 300) (product name: TINUVIN 1130, manufactured by Ciba-Geigy Corporation), isooctyl-3- [3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxy Phenyl] propionate (manufactured by Ciba Geigy Japan, product name: TINUVIN 384), 2- (3-dodecyl-5-methyl-2-hydroxyphenyl) benzotriazole (manufactured by Ciba Geigy Japan, product name: TINUVIN 571), 2 -(2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole , 2- (2′-Hydroxy-4′-octoxyphenyl) benzotria 2- [2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl] benzotriazole, 2,2-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol], 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (manufactured by Nippon Ciba-Geigy Co., Ltd., product name: TINUVIN900).

  Specific examples of radically polymerizable benzotriazole-based UV absorbers include 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole (manufactured by Otsuka Chemical Co., Ltd., product name: RUVA- 93), 2- (2′-hydroxy-5′-methacryloxyethyl-3-tert-butylphenyl) -2H-benzotriazole, 2- (2′-hydroxy-5′-methacrylyloxypropyl-3-tert) -Butylphenyl) -5-chloro-2H-benzotriazole, 3-methacryloyl-2-hydroxypropyl-3- [3 '-(2 "-benzotriazolyl) -4-hydroxy-5-tert-butyl] Phenyl propionate (manufactured by Nippon Ciba-Geigy Co., Ltd., product name: CGL-104).

Specific examples of triazine-based ultraviolet absorbers include TINUVIN400 (product name, manufactured by Ciba Geigy Japan).
As the light stabilizer, hindered amine light stabilizers are preferable, among them, those having low basicity are more preferable, and those having a base constant (pKb) of 8 or more are particularly preferable. Specifically, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (2,2,6,6-tetramethylpiperidyl) sebacate, bis (1,2,2,6, 6-pentamethyl-4-piperidyl) 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-butylmalonate, 1- [2- [3- (3,5-di-tert- Butyl-4-hydroxyphenyl) propynyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propynyloxy] -2,2,6,6-tetramethylpiperidine, A mixture of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2,6,6-pentamethyl-4-piperidyl-sebacate (Nippon Ciba Geigy ( ), Product name: TINUVIN292), bis (1-octyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, TINUVIN123 (product name, manufactured by Nihon Ciba-Geigy Corporation), and the like.

  Specific examples of the radical polymerizable hindered amine light stabilizer include 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, 1,2,2,6,6-pentamethyl-4-piperidyl acrylate, 2, 2,6,6-tetramethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl acrylate, 1,2,2,6,6-pentamethyl-4-iminopiperidyl methacrylate, 2, 2,6,6, -tetramethyl-4-iminopiperidyl methacrylate, 4-cyano-2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4-cyano-1,2,2,6,6- Examples include pentamethyl-4-piperidyl methacrylate.

  In the present invention, the ultraviolet absorber and / or light stabilizer is introduced into the aqueous resin dispersion by being present during emulsion polymerization for producing the aqueous resin dispersion, and the ultraviolet absorber and / or light stabilizer is formed into a film. A method of introducing by mixing with an auxiliary agent and adding to an aqueous resin dispersion, an ultraviolet absorber and / or a light stabilizer are mixed with a film forming auxiliary agent, emulsified by adding a surfactant and water, The method of introduce | transducing by adding to an aqueous resin dispersion is mentioned. In addition, when an ultraviolet absorber and a light stabilizer are used in combination, it exhibits excellent durability due to a synergistic effect.

  The aqueous resin dispersion used in the aqueous resin composition of the present invention preferably has an average particle size of the dispersoid of 30 to 500 nm. The mass ratio of the dispersoid (solid content) in the obtained emulsion to the aqueous medium as the dispersion medium is 70/30 or less, preferably 30/70 or more and 65/35 or less.

  The aqueous resin composition of the present invention is useful as a coating material, a base treatment material or finishing material for building materials, a paper processing agent, or a finishing material for woven fabrics and non-woven fabrics. Paints, building finishing materials for various bases such as concrete, cement mortar, slate board, calcium silicate board, gypsum board, extrusion molding board, inorganic building materials such as foamable concrete, building materials based on woven or non-woven fabric, and metal building materials Main materials and top coats for multilayer finish coating materials, thin finish coating materials, thick finish coating materials, stone-like finish materials, synthetic paint emulsion paints such as gloss paint, metal paints, wood paints, tiles It is useful as a coating material.

  The present invention will be described in detail with reference to production examples of aqueous resin dispersions, examples of aqueous resin compositions, and comparative examples, but the present invention is not limited to these examples. In addition, the part and% in the manufacture example of an aqueous resin dispersion, the Example of an aqueous resin composition, and a comparative example represent a mass part and the mass%, respectively. Moreover, about the physical-property test of the obtained aqueous resin composition, the coating material was adjusted with the compounding composition shown below using this aqueous resin composition, and the test was implemented according to the test method shown below.

<Coating composition>
-Preparation of pigment dispersion Dispersant: SN Dispersant 5027
(Product name, manufactured by San Nopco) 20% aqueous solution 5.00 parts 25% ammonia water 0.50 parts Propylene glycol 23.50 parts Water 147.80 parts Tyco CR-97 (trade name, manufactured by Ishihara Sangyo Co., Ltd.) ) 333.55 parts Antifoam: SN deformer 1310
(Trade name, manufactured by San Nopco Co., Ltd.) 2.85 parts The above-mentioned composition was dispersed for 20 minutes in a tabletop sand mill to obtain a pigment dispersion.
・ Production of enamel paint Each water-based resin composition (solid content conversion) 500.00 parts 50 parts ethylene glycol monobutyl ether and 50 parts water
100.00 parts CS-12 (product name, manufactured by Chisso Corporation) 50.00 parts The above pigment dispersion 513.20 parts Thickener: Adecanol UH-438 (Asahi Denka Kogyo Co., Ltd.)
10% aqueous solution

<Test method>
-Evaluation of polymerization stability The aqueous resin dispersion obtained after the emulsion polymerization was filtered through a 100-mesh filter cloth, and the residue mass was divided by the mass of the aqueous resin dispersion to obtain the residue rate.
(Judgment criteria) ○: Residue rate is less than 100 ppm
Δ: Residue rate is 100 ppm or more
X: Generation of a large amount of aggregates and measurement of particle diameter The average particle diameter of the obtained aqueous resin dispersion was measured with a Microtrac particle size distribution meter manufactured by Leeds & Northrup.
-Solid content, such as aqueous resin dispersion It is a dry mass after drying solid content measuring objects, such as an aqueous resin dispersion, at 105 degreeC for 3 hours.
-Resin solid content of aqueous resin dispersion The mass obtained by subtracting the dry weight of the surfactant, polymerization initiator, etc. from the dry weight of the aqueous resin dispersion after drying at 105 ° C for 3 hours.
・ Measurement of solid fraction of aqueous resin dispersion, etc. Precisely weigh about 1 g of the solid dispersion fraction, such as water dispersion, in an aluminum dish of which mass is known in advance, and measure it at 105 ° C. with a constant temperature dryer. After drying for a period of time, the mixture is allowed to cool for 30 minutes in a desiccator containing silica gel and then weighed accurately. The solid content was obtained by dividing the mass after drying of the substance by the mass before drying.
・ Minimum deposition temperature (MFT)
The object was coated on an aluminum plate placed on a thermal gradient tester with a 0.1 mm applicator and dried, and the highest temperature at which cracks occurred in the coating film was defined as the lowest film formation temperature (MFT). .
-Enamel gloss The above-mentioned enamel paint composition is applied to the wire coater No. 50 was applied to an alumite sulfate plate, forcedly dried at 100 ° C. for 5 minutes, and then dried at 50 ° C. for 1 week. With respect to the dried coating film, the 60 ° gloss was measured with a gloss meter (Micro Trigloss μ, manufactured by BYK Gardner).
-Weather resistance The above-mentioned enamel coating composition was applied to a wire coater No. 50 was applied to an alumite sulfate plate, forcedly dried at 100 ° C. for 5 minutes, and then dried at 50 ° C. for 1 week. Subsequently, an exposure test (rain cycle; 18 minutes / 2 hours, black panel temperature 60 to 66 ° C.) was performed using a sunshine type weatherometer (Suga Test Instruments Co., Ltd., WEL-SUN-DC). Changes in appearance after 2000 hours of exposure were observed. Judgment criteria are as follows.
A: No change.
○;
Δ: Shiny and partially cracked.
X: Cracks are seen on the entire surface with glossiness.
-Blocking resistance The above-mentioned enamel coating composition was adjusted with a film forming auxiliary amount (ethylene glycol monobutyl ether and CS-12) so that the MFT was 10 ° C, and was applied with an 8 mil applicator. After forced-drying for 3 minutes, it was cured for 3 hours in a room adjusted to 23 ° C. and 50% humidity. Next, it quickly moved into a dryer at 60 ° C. and left for 1 minute, after which gauze was placed on the surface of the coating film, a weight was placed thereon, and a load of 10 kg / cm ² was applied for 24 hours. And after cooling to normal temperature, gauze was peeled off slowly, the state of the coating film was observed visually, and it evaluated according to the following reference | standard.
A: There is almost no trace of gauze.
○: A trace of gauze is seen.
Δ: Reticulated traces.
X: It is difficult to peel off the gauze.

Production of aqueous resin dispersion [Production Example 1]
In a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 574.1 parts of water, anionic reactive surfactant (product name: Aqualon KH-1025, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 6.4 parts of 25% aqueous solution was added and the temperature in the reaction vessel was raised to 80 ° C., and 5 minutes after adding 15 parts of 2% aqueous solution of ammonium persulfate, 305 parts of methyl methacrylate and 180 parts of cyclohexyl methacrylate were added. 10 parts of 2-hydroxyethyl methacrylate, 5 parts of methacrylic acid, 5 parts of γ-methacryloxypropyltrimethoxysilane (SZ6030, manufactured by Toray Dow Corning Co., Ltd.), an anionic surfactant (product name: Newcor 707SF, 40 parts of a 30% solution of Nippon Emulsifier Co., Ltd., nonionic surfactant (product name: Emulgen 120, manufactured by Kao Corporation) 0% aqueous solution of 20 parts of a 2% aqueous solution of 25 parts of ammonium persulfate, the emulsion mixture to flow over a period of 105 minutes from the dropping tank of water 204.5 parts. During the inflow, the temperature of the reaction vessel is maintained at 80 ° C. After the inflow is completed, the temperature of the reaction vessel is raised to 80 ° C. and maintained for 30 minutes.
Next, 141 parts of methyl methacrylate, 50 parts of cyclohexyl methacrylate, 249 parts of n-butyl acrylate, 40 parts of 2-hydroxyethyl methacrylate, 10 parts of methacrylic acid, 10 parts of acrylic acid, 30% solution of Newcol 707SF An emulsion mixture consisting of 10 parts, 25 parts of a 2% aqueous solution of ammonium persulfate and 237.5 parts of water is allowed to flow in over 90 minutes. During the inflow, the temperature of the reaction vessel is maintained at 80 ° C. After the inflow is completed, 67 parts of water is added and the temperature of the reaction vessel is raised to 80 ° C. and maintained for 90 minutes.
After cooling to room temperature, a 25% aqueous ammonia solution was added to adjust the pH to 8.5, followed by filtration through a 100 mesh wire net. The dry mass of the filtered aggregate was as small as 0.04% based on the total monomers. The obtained aqueous resin dispersion had a solid content of 46.0%, a particle size of 128 nm, and a single distribution.

[Production Examples 2 to 5]
Except for changing the type and amount of each component used in the first stage and second stage emulsified mixed liquid and the feed time of each emulsified mixed liquid as shown in Table 1, in the same manner as in Production Example 1, An aqueous resin dispersion was obtained. Table 1 shows the properties of the obtained aqueous resin dispersion.
In addition, the quantity of each polymerizable monomer was shown by the ratio with respect to 100 weight part of total polymerizable monomer components used in both stages.

[Production Example 6]
In a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 574.1 parts of water, anionic reactive surfactant (product name: Aqualon KH-1025, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) 6.4 parts of 25% aqueous solution was added, the temperature in the reaction vessel was raised to 80 ° C., and 5 minutes after adding 15 parts of 2% aqueous solution of ammonium persulfate, 310 parts of methyl methacrylate and 180 parts of cyclohexyl methacrylate were added. , 5 parts of 2-hydroxyethyl methacrylate, 5 parts of methacrylic acid, 40 parts of a 30% solution of an anionic surfactant (NEWCOL-707SF, Nippon Emulsifier), nonionic surfactant (product name: Emulgen 120, Kao ( 105% of an aqueous solution of 20% 20% aqueous solution, 25 parts of 2% aqueous solution of ammonium persulfate, and 213.5 parts of water. It is allowed to flow over. In addition, from 5 minutes after the start of dripping, 30 parts of γ-methacryloxypropyltrimethoxysilane (SZ6030, manufactured by Toray Dow Corning Co., Ltd.), dimethyldimethoxysilane (AY43-004, Toray Dow Corning Co., Ltd.) A mixed solution of 30 parts and 20 parts of methyltrimethoxysilane (SZ6070, manufactured by Toray Dow Corning Co., Ltd.) is dropped from another dropping tank over 90 minutes. During the inflow, the temperature of the reaction vessel is maintained at 80 ° C. After the inflow of the emulsified liquid mixture is completed, the temperature of the reaction vessel is raised to 80 ° C. and maintained for 30 minutes.
Next, 153 parts of methyl methacrylate, 50 parts of cyclohexyl methacrylate, 252 parts of n-butyl acrylate, 25 parts of 2-hydroxyethyl methacrylate, 10 parts of methacrylic acid, 10 parts of acrylic acid, and a 30% solution of NEWCOL-707SF An emulsion mixture consisting of 10 parts, 25 parts of a 2% aqueous solution of ammonium persulfate and 243.5 parts of water is allowed to flow in over 90 minutes. During the inflow, the temperature of the reaction vessel is maintained at 80 ° C. After the inflow is completed, 67 parts of water is added and the temperature of the reaction vessel is raised to 80 ° C. and maintained for 90 minutes.
After cooling to room temperature, a 25% aqueous ammonia solution was added to adjust the pH to 8.5, followed by filtration through a 100 mesh wire net. The dry mass of the filtered aggregate was as small as 0.04% based on the total monomers. The obtained aqueous resin dispersion had a solid content of 46.1%, a particle size of 128 nm, and a single distribution.

[Production Example 7]
An aqueous resin dispersion was obtained in the same manner as in Production Example 8, except that the type and amount of each component used in the first and second emulsion mixtures were changed as shown in Table 1. Table 1 shows the properties of the obtained aqueous resin dispersion.

[Production Examples 8 to 13]
In the same manner as in Example 1, except that the type and amount of each component used in the first and second emulsion mixtures and the feed time of each emulsion mixture were changed as shown in Table 1, A resin dispersion was obtained. Table 1 shows the properties of the obtained aqueous resin dispersion.

[Example 1]
100 parts of the aqueous resin dispersion (solid content: 45.2%) of Production Example 1 was stirred with a stirrer, and 4.6 parts of Duranate WT30-100 (manufactured by Asahi Kasei Chemicals Corporation, solid content: 100%) 4.6 parts, water 11.7 parts was added to obtain an aqueous resin composition. With respect to this aqueous resin composition, an enamel paint was prepared with the above-mentioned paint formulation, and each test was performed. The results are shown in Table 2.

[Examples 2 to 10]
100 parts of the aqueous resin dispersions of Production Examples 2 to 7 were stirred with a stirrer, and Epocross WS-700 (manufactured by Nippon Shokubai Co., Ltd., solid content 25%), Carbodilite E-02 (Nisshinbo Industries Co., Ltd.) Co., Ltd., solid content 40%) and water shown in Table 2 were added to obtain an aqueous resin composition. With respect to this aqueous resin composition, an enamel paint was prepared with the above-mentioned paint formulation, and each test was performed. The results are shown in Table 2.

[Comparative Examples 1-2]
An amount of water shown in Table 3 was added to 100 parts of the aqueous resin dispersions of Production Examples 2 and 3 to obtain an aqueous resin composition. With respect to this aqueous resin composition, an enamel paint was prepared with the above-mentioned paint formulation, and each test was performed. The results are shown in Table 3.
In Comparative Examples 1 and 2, the properties of the aqueous resin dispersions of Production Examples 2 and 3 used in the aqueous resin composition satisfy the requirements of the present invention, but no crosslinking agent is used. The blocking resistance is poor.

[Comparative Examples 3 to 4]
100 parts of the aqueous resin dispersion of Production Example 8 was stirred with a stirrer, and hardener SC (manufactured by Asahi Kasei Chemicals Co., Ltd., solid content 50%) as a semicarbazide-based curing agent, and adipic acid dihydrazide (ADH) as an organic hydrazine compound. (Otsuka Chemical Co., Ltd., 100% solid content) and water were added in the amounts shown in Table 3 to obtain an aqueous resin composition. With respect to this aqueous resin composition, an enamel paint was prepared with the above-mentioned paint formulation, and each test was performed. The results are shown in Table 3.
In Comparative Examples 2 to 4, the properties of the aqueous resin dispersion of Production Example 8 used in the aqueous resin composition satisfy the requirements of the present invention. However, in the crosslinking reaction by the hardener SC or ADH added as a crosslinking agent, Since the crosslinking effect is insufficient, the blocking resistance is poor.

[Comparative Examples 5 to 10]
100 parts of the aqueous resin dispersions of Production Examples 9 to 13 were stirred with a stirrer, and Epocross WS-700 (manufactured by Nippon Shokubai Co., Ltd., solid content 25%), Carbodilite E-02 (Nisshinbo Industries Co., Ltd. Co., Ltd., solid content 40%), and water in amounts shown in Table 3 were added to obtain an aqueous resin composition. With respect to this aqueous resin composition, an enamel paint was prepared with the above-mentioned paint formulation, and each test was performed. The results are shown in Table 3.
In Comparative Examples 5 to 6, since the Tg of the high Tg component of the aqueous resin dispersion of Production Example 9 used in the aqueous resin composition is less than 50 ° C., even when a crosslinking agent is added, the blocking resistance is high. It is bad.
In Comparative Example 7, since the ratio of the high Tg component / low Tg component of the aqueous resin dispersion of Production Example 11 used in the aqueous resin composition was 4/6, even when a crosslinking agent was added, anti-blocking property The sex is poor.
Comparative Example 8 is a polymerizable monomer in which the aqueous resin dispersion of Production Example 11 used in the aqueous resin composition has a water solubility at 20 ° C. of 0.1% by weight or more among all polymerizable monomers. Since the amount used is 50% or less, the blocking resistance is poor even when a crosslinking agent is added.
Since Comparative Example 9 does not use methyl methacrylate or cyclohexyl methacrylate as the low Tg component of the aqueous resin dispersion of Production Example 12 used in the aqueous resin composition, the enamel gloss is poor.
Since the comparative example 10 does not use cyclohexyl methacrylate and Si-containing compound in the aqueous resin dispersion of Production Example 14 used for the aqueous resin composition, the weather resistance is poor.
Abbreviations in the table are as follows. Moreover, Tg value of each homopolymer used in order to calculate the glass transition temperature (Tg / degreeC) of a polymerizable monomer by Fox formula was shown in ().
MMA: Methyl methacrylate (105)
BA: n-butyl acrylate (-45)
BMA: n-butyl methacrylate (22)
2EHA: 2-ethylhexyl acrylate (-55)
CHMA: cyclohexyl methacrylate (83)
2HEMA: 2-hydroxyethyl methacrylate (55)
AA: Acrylic acid (87)
MAA: Methacrylic acid (144)
DAAM: diacetone acrylamide (65)

  The aqueous resin dispersion of the present invention is suitable for paint and coating applications.

Claims (12)

  An aqueous resin composition for an enamel paint comprising an aqueous resin dispersion and a crosslinking agent as essential components.   The aqueous solution according to claim 1, wherein the high-Tg resin component of the aqueous resin dispersion contains an alkoxysilane group-containing polymerizable monomer (A) and a cycloalkyl group-containing polymerizable monomer (B). Resin composition.   The aqueous resin composition according to claim 1 or 2, wherein no reactive emulsifier is used as a high Tg resin component of the aqueous resin dispersion.   The aqueous resin dispersion is an aqueous resin dispersion obtained by polymerization using two or more kinds of polymerizable monomers having different glass transition temperatures (Tg), and the aqueous resin dispersion has a glass transition It consists of a high Tg resin component having a temperature (Tg) of 50 ° C. or more and a low Tg resin component having a glass transition temperature (Tg) of 40 ° C. or less, and the ratio of the high Tg resin component to the low Tg resin component is high Tg resin component / The aqueous resin composition according to claim 1, comprising a low Tg resin component (weight ratio) = 46/54 to 70/30.   5. The aqueous solution according to claim 1, comprising a polymerizable monomer containing a carboxyl group and a hydroxyl group-containing polymerizable monomer as a low Tg resin component of the aqueous resin dispersion. Resin composition.   The cross-linking agent is at least one selected from a compound having an isocyanate group, a compound having an aziridine ring, a compound having an oxazoline ring, and a compound having a carbodiimide group, and the blending amount thereof is a function of the aqueous resin dispersion. It is 0.1-2 equivalent with respect to group, The aqueous resin composition in any one of Claims 1-5 characterized by the above-mentioned. The aqueous resin composition according to any one of claims 1 to 6, wherein the aqueous resin dispersion also contains a Si-containing compound represented by the following formula (1).
_{^{(R 1) n -Si- (R}} 2) 4-n (1)
(In the formula, n is an integer of 0 to 3, and R ¹ is selected from hydrogen, an aliphatic hydrocarbon group having ^{1 to} 16 carbon atoms, an aryl group having 5 to 10 carbon atoms, and a cycloalkyl group having 5 to 6 carbon atoms. N R ¹ may be the same or different, and R ² is selected from an alkoxy group having 1 to 8 carbon atoms, an acetoxy group, and a hydroxyl group, and 4-n R ² is the same. Or it may be different.)   The amount of water exceeding 20% of the entire polymerizable monomer used to obtain the aqueous resin dispersion has a water solubility at 20 ° C. of 0.1% by mass or more. The aqueous resin composition according to any one of the above.   The aqueous resin according to any one of claims 1 to 8, wherein the polymerizable monomer of the low Tg resin component of the aqueous resin dispersion contains 5% by mass or more of methyl methacrylate and cyclohexyl methacrylate, respectively. Composition.   A structure in which the high Tg resin component of the aqueous resin dispersion is composed of a central portion (core) of the aqueous resin dispersion particles, and the low Tg resin component of the aqueous resin dispersion is composed of an outer portion (shell) of the aqueous resin dispersion particles. The aqueous resin composition according to any one of claims 1 to 9, wherein   The aqueous resin composition according to any one of claims 1 to 10, which is obtained by emulsion polymerization in two or more steps.   The aqueous resin composition according to claim 11, wherein the aqueous resin composition is produced at a pH of 4 or less during emulsion polymerization.