JP2015166428A - Aqueous emulsion, method for producing the same, and aqueous coating agent film using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an aqueous emulsion that can form a coating film having sufficient film formability and coating film characteristics and, particularly, can form a coating film excellent in adhesion to an exterior wall of a building and a ceramic-based siding board.SOLUTION: The aqueous emulsion includes an aqueous polymer particle having a core-shell structure. The aqueous emulsion is composed of: an aqueous polymer particle having a core-shell structure of a shell layer comprising an aqueous polymer A including (a1) an ethylenically unsaturated monomer containing no carboxyl group and (a2) an ethylenically unsaturated monomer containing a carboxyl group, having a carboxyl group derived from the monomer (a2) neutralized, having a predetermined Tg and having a predetermined weight average molecular weight; and a core layer comprising an aqueous polymer B including (b1) an ethylenically unsaturated monomer containing no carboxyl group and having a predetermined Tg so as to satisfy a mass ratio of the polymer A and the polymer B of 0.5/99.5 to 99.5/0.5, (1) Tg of the polymer B≥Tg of the polymer A, and (2) Tg of the particle≥MFT of the particle.

Description

  The present invention relates to an aqueous emulsion, a method for producing the same, and an aqueous coating agent film using the same. More specifically, an aqueous emulsion excellent in production stability, film-forming properties and coating film properties (particularly adhesion, water resistance, warm water resistance, water permeability resistance), a method for producing the same, and an aqueous coating agent using the same Related to film.

  In recent years, from the viewpoints of environmental protection and safety, there has been an increase in the movement of reducing VOC (volatile organic compounds), and paints have been shifted from conventional solvent systems to water-based ones. However, conventional water-based paints using water-based emulsions have film-forming properties and coating properties (water resistance, warm water resistance, water permeability, moisture resistance, adhesion, blocking resistance, weather resistance, and frost damage resistance). Etc. were insufficient.

  As a paint for solving the above problems, for example, an aqueous paint containing an alkoxysilane group-containing emulsion having a core-shell structure and having a glass transition temperature of the shell portion higher than that of the core portion has been proposed. (For example, see Patent Documents 1 and 2). In addition, water-soluble resin that can be dissolved in water medium (realized solubilization) by copolymerizing acrylic ester and carboxyl group-containing unsaturated monomer together with hydrophobic fine particles and then neutralizing with alkali An emulsion containing (polymer emulsifier) has been proposed (see, for example, Patent Document 3).

  However, the above technique has the following problems. In other words, although those proposed in Patent Documents 1 and 2 are improved in blocking resistance and stain resistance, the minimum film forming temperature is increased, so that the film forming property is lowered and the formed coating film is also used. It becomes hard and brittle, and the water resistance, frost damage resistance and the like are also reduced. Therefore, a large amount of organic solvent is required to obtain sufficient coating properties, and there are problems in terms of environmental protection and safety. Although what was proposed by patent document 3 is excellent in the impregnation adhesiveness to foundation | substrate base materials, such as an inorganic building material, since it uses the water-soluble resin which is a low molecule, there exists a problem in water resistance, and also it is resistant. Permeability has not reached the target level.

  Since film formation of water-based paint is performed by agglomeration and fusion of aqueous polymer particles contained in water-based paint, it is necessary to control the film-forming property corresponding to the use environment and drying temperature. It is necessary to control the minimum film-forming temperature (hereinafter referred to as MFT) of the polymer particles. MFT means the temperature required for an emulsion containing aqueous polymer particles to deform as the water evaporates to form a coating film, and is approximately the glass transition temperature of the aqueous polymer particles (hereinafter referred to as Tg). ). In general, a lower MFT forms a film even at a lower temperature, so it is easier to handle at the time of coating, but an aqueous emulsion containing aqueous polymer particles having a low Tg has a lower Tg of the coating film, and has a blocking resistance and contamination resistance. It is not possible to obtain sufficient coating properties such as properties. For this reason, there has been a demand for the development of water-based paints that can achieve both film-forming properties and coating film properties.

  An aqueous resin dispersion comprising a high Tg component having a Tg of 50 ° C. or higher and a low Tg component having a glass transition temperature of 40 ° C. or lower as a water-based paint capable of achieving both film-forming properties and coating properties, and MFT is polymerizable. An aqueous resin dispersion characterized by being 10 ° C. or more lower than the calculated Tg of the monomer has been proposed (see, for example, Patent Document 4). However, although the film-forming property is slightly improved by lowering the MFT, the one proposed in Patent Document 4 is not necessarily sufficient for practical use because the water permeability / moisture resistance is not particularly improved. There wasn't.

JP 2002-69365 A JP 2008-101140 A JP 2006-241427 A JP 2008-63567 A

  Accordingly, an object of the present invention is an aqueous emulsion that can be formed as a coating film having excellent film forming properties and coating film properties (particularly adhesion, water resistance, warm water resistance, and water permeability resistance). In particular, it is to provide an aqueous emulsion that can be formed as a coating film excellent in adhesion and water permeability resistance to an exterior wall surface of a building and a ceramic siding board.

In order to achieve the above object, the present invention provides the following aqueous emulsion, a production method thereof, and an aqueous coating agent film using the same.
[1] An aqueous emulsion obtained by emulsifying and dispersing aqueous polymer particles in an aqueous dispersion medium, wherein the aqueous polymer particles have a core-shell structure obtained by two or more emulsion polymerization reactions, The core-shell structure is composed of a shell layer made of an aqueous polymer A and a core layer made of an aqueous polymer B, and the aqueous polymer A constituting the shell layer is a non-carboxylized ethylenic component as a constituent component. While containing 80.0-99.5 mass% of unsaturated monomers (a1) and 0.5-20.0 mass% of carboxyl group-containing ethylenically unsaturated monomers (a2), the carboxyl group-containing ethylene The carboxyl group derived from the polymerizable unsaturated monomer (a2) is neutralized in the polymerization stage, has a glass transition temperature of −40 ° C. to 80 ° C., and has a weight average molecular weight of 50,000 or more. The aqueous polymer B constituting the core layer contains a carboxyl group-free ethylenically unsaturated monomer (b1) as a constituent component, and has a glass transition temperature of 0 ° C. to 120 ° C. The mass ratio of the polymer A and the aqueous polymer B (aqueous polymer A / aqueous polymer B) is 0.5 / 99.5 to 99.5 / 0.5 (however, the emulsion polymerization reaction) Is 3 stages or more, the mass of the aqueous polymer B means the total mass of the aqueous polymer constituting the core layer) and satisfies the following conditions (1) to (2): An aqueous emulsion.
(1) Glass transition temperature of the aqueous polymer B forming the core layer ≧ glass transition temperature of the aqueous polymer A constituting the shell layer (2) Glass transition temperature of the aqueous polymer particles ≧ the aqueous weight Minimum film-forming temperature of coalesced particles (provided that the film-forming aid is not included in the aqueous polymer particles)

[2] The carboxyl group-free ethylenically unsaturated monomer (a1) is a (meth) acrylic acid alkyl ester monomer (including a cyclic alkyl ester) whose alkyl group has 1 to 12 carbon atoms, a vinyl group One or more selected from the group consisting of a monomer containing a monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, an alkoxysilyl group-containing unsaturated monomer, and a piperidyl group-containing unsaturated monomer The aqueous emulsion according to [1], which is a monomer of
[3] The carboxyl group-containing ethylenically unsaturated monomer (a2) is one or more monomers selected from the group consisting of (meth) acrylic acid, maleic anhydride, and itaconic acid [1] or The aqueous emulsion according to [2].
[4] The aqueous emulsion according to [1] to [3], wherein the water permeability of the formed coating film is less than 1,500 (ml / m ² · 24 h).

[5] A method for producing an aqueous emulsion in which an aqueous emulsion in which aqueous polymer particles having a core-shell structure are emulsified and dispersed in an aqueous dispersion medium is obtained by an emulsion polymerization reaction of two or more stages. As a polymerization reaction, 80.0 to 99.5% by mass of the carboxyl group-free ethylenically unsaturated monomer (a1) and 0% of the carboxyl group-containing ethylenically unsaturated monomer (a2) are contained in the aqueous dispersion medium. The mixture of monomers containing 5 to 20.0% by mass is subjected to an emulsion polymerization reaction, and during the first emulsion polymerization reaction and / or after the first emulsion polymerization reaction, the carboxyl is added by a basic compound. Aqueous polymer A constituting the shell layer of the core-shell structure of the aqueous polymer particles by neutralizing the carboxyl group derived from the group-containing ethylenically unsaturated monomer (a2) And a mixture of monomers containing a carboxyl group-free ethylenically unsaturated monomer (b1) in the presence of the aqueous polymer A constituting the shell layer as a second stage emulsion polymerization reaction. A step of obtaining an aqueous polymer B constituting the core layer of the core-shell structure of the aqueous polymer particles by carrying out an emulsion polymerization reaction, and an emulsion polymerization reaction after the third step, if necessary, Repeating the emulsion polymerization reaction of the eye to obtain an aqueous polymer constituting the third and subsequent core layers of the core-shell structure of the aqueous polymer particles, the emulsion polymerization reaction of the first stage The aqueous polymer A constituting the shell layer obtained by the method has a glass transition temperature of −40 ° C. to 80 ° C., a weight average molecular weight of 50,000 or more, and neutralization of the carboxyl group Without being solubilized later The aqueous polymer B that forms a white emulsion and is obtained by the emulsion polymerization reaction after the second stage has a glass transition temperature of 0 ° C. to 120 ° C., and the aqueous polymer A The mass ratio with respect to the aqueous polymer B (aqueous polymer A / aqueous polymer B) is 0.5 / 99.5 to 99.5 / 0.5 (provided that the emulsion polymerization reaction is three or more stages). The mass of the aqueous polymer B means the total mass of the aqueous polymer constituting the core layer) and the following conditions (1) to (2) are satisfied: Production method.
(1) Glass transition temperature of the aqueous polymer B forming the core layer ≧ glass transition temperature of the aqueous polymer A constituting the shell layer (2) Glass transition temperature of the aqueous polymer particles ≧ the aqueous weight Minimum film-forming temperature of coalesced particles (provided that the film-forming aid is not included in the aqueous polymer particles)

[6] Furthermore, condition (3) the pH after neutralizing the carboxyl group of the aqueous polymer A constituting the shell layer is 5.0 to 10.0, and the absorbance after neutralization is neutralized. The method for producing an aqueous emulsion according to [5], wherein the ratio is 99.5 to 40% of the previous absorbance.
[7] The carboxyl group-free ethylenically unsaturated monomer (a1) is a (meth) acrylic acid alkyl ester monomer (including a cyclic alkyl ester) whose alkyl group has 1 to 12 carbon atoms, a vinyl group One or more selected from the group consisting of a monomer containing a monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, an alkoxysilyl group-containing unsaturated monomer, and a piperidyl group-containing unsaturated monomer The method for producing an aqueous emulsion according to [5] or [6], wherein
[8] The carboxyl group-containing ethylenically unsaturated monomer (a2) is one or more monomers selected from the group consisting of (meth) acrylic acid, maleic anhydride, and itaconic acid. [7] The method for producing an aqueous emulsion according to any one of [7].
[9] The basic compound is any one of [5] to [8], which is one or more compounds selected from the group consisting of amine compounds (including amino alcohol and ammonia), sodium hydroxide, and potassium hydroxide. The manufacturing method of the aqueous emulsion as described in any one.

[10] Using the aqueous emulsion according to any one of [1] to [4] or the aqueous emulsion obtained by the method for producing an aqueous emulsion according to any one of [5] to [9] An aqueous coating agent film, wherein the film has a water permeability of less than 1,500 (ml / m ² · 24 h).

  According to the present invention, an aqueous emulsion that can be formed as a coating film having excellent film-forming properties and coating film properties (particularly adhesion, water resistance, warm water resistance, water permeability resistance) In particular, it is possible to provide an aqueous emulsion that can be formed as a coating film having excellent adhesion to an exterior wall surface of a building or a ceramic siding board.

It is a graph which shows the relationship of MFT (degreeC) with respect to Tg of the water-based emulsion obtained by the Example and the comparative example.

  Hereinafter, the aqueous emulsion and the method for producing the same according to the present invention will be described in more detail with reference to embodiments thereof. The term “(meth) acryl” in the claims and the specification of the present invention means both “acryl” and “methacryl”, and the term “(meth) acrylate” ”And“ methacrylate ”.

I. Aqueous emulsion The aqueous emulsion of the present embodiment is an aqueous emulsion obtained by emulsifying and dispersing aqueous polymer particles in an aqueous dispersion medium, and the aqueous polymer particles are obtained by an emulsion polymerization reaction of two or more stages. It has a core-shell structure, and the core-shell structure is composed of a shell layer made of an aqueous polymer A and a core layer made of an aqueous polymer B. And the aqueous polymer A which comprises the said shell layer is 80.0-99.5 mass% of carboxyl group-free ethylenically unsaturated monomers (a1) as a structural component, and a carboxyl group-containing ethylenically unsaturated monomer. While containing 0.5 to 20.0 mass% of the monomer (a2), the carboxyl group derived from the carboxyl group-containing ethylenically unsaturated monomer (a2) is neutralized, and the glass transition temperature is −40 ° C. to It is characterized by being 80 ° C. and having a weight average molecular weight of 50,000 or more. And the aqueous polymer B which comprises the said core layer contains a carboxyl group non-containing ethylenically unsaturated monomer (b1) as a structural component, and glass transition temperature is 0 to 120 degreeC, It is characterized by the above-mentioned. To do. The aqueous polymer particles having the core-shell structure described above have a mass ratio (aqueous polymer A / aqueous polymer B) between the aqueous polymer A constituting the shell layer and the aqueous polymer B constituting the core layer. 0.5 / 99.5 to 99.5 / 0.5 (however, when the emulsion polymerization reaction is three or more stages, the mass of the aqueous polymer B is the total mass of the aqueous polymer constituting the core layer) And the following conditions (1) to (2) are satisfied.
(1) Glass transition temperature of aqueous polymer B forming the core layer ≧ glass transition temperature of aqueous polymer A constituting the shell layer (2) Glass transition temperature of aqueous polymer particles ≧ minimum film formation of aqueous polymer particles Temperature (however, when water-soluble polymer particles do not contain a film-forming aid)
Hereinafter, each component, characteristic, and use of the aqueous emulsion of the present embodiment will be specifically described.

[1. Aqueous polymer particles]
The aqueous polymer particles of the present embodiment are characterized by having a core-shell structure obtained by an emulsion polymerization reaction of two or more stages. And the said core-shell structure is comprised from the shell layer which consists of the aqueous polymer A mentioned later, and the core layer which consists of the aqueous polymer B mentioned later, It is characterized by the above-mentioned. When the aqueous polymer particles of the present embodiment have a specific core-shell structure, the coating film formed by the aqueous emulsion of the present embodiment has a water resistance, a warm water resistance, a water resistance, a moisture resistance, It has excellent coating properties such as adhesion, blocking resistance, weather resistance, and frost damage resistance, and film-forming properties, and in particular, has excellent adhesion, water resistance, warm water resistance, and water permeability resistance. Details of the reason will be described later.

(Aqueous polymer A constituting shell layer)
The aqueous polymer A constituting the shell layer comprises 80.0 to 99.5% by mass of a carboxyl group-free ethylenically unsaturated monomer (a1) as a constituent component and a carboxyl group-containing ethylenically unsaturated monomer ( It is necessary to contain 0.5-20.0 mass% of a2). When the content ratio of the carboxyl group-free ethylenically unsaturated monomer (a1) in the aqueous polymer A exceeds 99.5% by mass, polymerization when the aqueous polymer B constituting the core layer described later is polymerized The stability of the liquid decreases, and aggregates of aqueous polymer particles are formed in the resulting aqueous emulsion. On the other hand, when the content ratio of the carboxyl group-free ethylenically unsaturated monomer (a1) in the aqueous polymer A is less than 80.0% by mass, the coating film formed by the finally obtained aqueous emulsion Water resistance decreases. When the content of the carboxyl group-containing ethylenically unsaturated monomer (a2) in the aqueous polymer A is less than 0.5% by mass, the aqueous polymer B constituting the core layer is polymerized. Not only does the stability of the polymerization solution decrease and sufficient production stability cannot be obtained, but aggregates of polymer particles are produced in the resulting aqueous emulsion. On the other hand, when the content ratio of the carboxyl group-containing ethylenically unsaturated monomer (a2) is more than 20.0% by mass, water resistance and hot water resistance of the coating film formed by the finally obtained aqueous emulsion Sex is reduced.

  The carboxyl group-free ethylenically unsaturated monomer (a1) includes (meth) acrylic acid alkyl ester monomers (including cyclic alkyl esters) whose alkyl group has 1 to 12 carbon atoms, vinyl group-containing One or more selected from the group consisting of a monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, an alkoxysilyl group-containing unsaturated monomer, and a piperidyl group-containing unsaturated monomer A monomer is preferred. Examples of (meth) acrylic acid alkyl ester monomers (including cyclic alkyl esters) having 1 to 12 carbon atoms in the alkyl group include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, and n-butyl (meth) ) Acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, etc. Examples of vinyl group-containing unsaturated monomers include styrene, α-methyl styrene, p-methyl styrene, t-methyl styrene, chlorostyrene, benzyl acrylate, vinyl toluene, acrylonitrile, methacrylonitrile, vinyl acetate. , Versatic acid Examples of the hydroxyl group-containing unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, and glycerol (meth) monoacrylate. Examples of the amide group-containing unsaturated monomer include (meth) acrylamide, N-methyl (meth) acrylamide, Nn-butyl (meth) acrylamide, Ni-propyl (meth) acrylamide, and Nt. -Butyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, diacetone (meth) acrylamide, N-methylol (meth) acrylamide and the like can be mentioned. Examples of the alkoxysilyl group-containing unsaturated monomer include , Vinyltrimethoxysilane, 3-methacryloxypropyl Examples of the unsaturated monomer containing piperidyl group include 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate and 2,2,6,6-tetramethyl. -4-piperidyl methacrylate can be used, and one or more selected from these groups can be used.

  Examples of the carboxyl group-containing ethylenically unsaturated monomer (a2) include (meth) acrylic acid, maleic anhydride, itaconic acid, and the like, and one or more selected from these groups are used. be able to.

  In the aqueous polymer A constituting the shell layer, the carboxyl group derived from the carboxyl group-containing ethylenically unsaturated monomer (a2) needs to be neutralized in the polymerization stage. When the carboxyl group is unneutralized, the orientation of the carboxylic acid on the particle surface is weak, so the coating film formed using the aqueous emulsion of the present embodiment should have sufficient water resistance and moisture resistance. I can't.

  As a compound used when neutralizing the carboxyl group derived from the carboxyl group-containing ethylenically unsaturated monomer (a2), any compound conventionally used for neutralization can be used without any problem. In particular, it is preferable to use a basic compound. Examples of the basic compound include amine compounds [eg, alkylamines such as ammonia, triethylamine, trimethylamine, and butylamine; alcohol amines such as 2-dimethylaminoethanol, diethanolamine, dimethylethanolamine, triethanolamine, and aminomethylpropanol ( Amino alcohols); morpholine and the like], sodium hydroxide and potassium hydroxide.

  The aqueous polymer A obtained as described above needs to have a glass transition temperature of −40 ° C. to 80 ° C. If the glass transition temperature of the aqueous polymer A is less than −40 ° C., the surface of the aqueous polymer particles is too soft, causing problems in blocking resistance and stain resistance. On the other hand, if the glass transition temperature exceeds 80 ° C., the aqueous polymer Since the particle surface is too hard, a large amount of film-forming aid is required, and frost damage is also a problem.

  The aqueous polymer A obtained as described above usually has a weight average molecular weight of 50,000 or more. If the weight average molecular weight of the aqueous polymer A is less than 50,000, the water resistance of the shell layer is lowered, and the water permeability and water resistance of the coating film formed by the aqueous emulsion obtained are lowered. There is.

(Aqueous polymer B constituting the core layer)
The aqueous polymer B constitutes the core layer of the aqueous polymer particles having a core-shell structure contained in the aqueous emulsion of the present embodiment. The aqueous polymer B constituting the core layer needs to contain a carboxyl group-free ethylenically unsaturated monomer (b1) as a constituent component. Examples of the carboxyl group-free ethylenically unsaturated monomer (b1) include the same compounds as the carboxyl group-free ethylenically unsaturated monomer (a1) that is a constituent of the aqueous polymer A. . Moreover, the aqueous polymer B which comprises a core layer can further contain the carboxyl group-containing ethylenically unsaturated monomer (a2) which is a structural component of the aqueous polymer A as a structural component.

  The aqueous polymer B constituting the core layer needs to have a glass transition temperature of 0 ° C to 120 ° C. When the glass transition temperature of the aqueous polymer B constituting the core layer is less than 0 ° C., the total glass transition temperature of the aqueous polymer particles is lowered, causing problems in blocking resistance and contamination resistance, while on the other hand, 120 ° C. If it exceeds 1, the glass transition temperature of the aqueous polymer particles becomes partly too high, which causes a problem in the fragility of the coating film.

  The mass ratio of the aqueous polymer A obtained by the first-stage emulsion polymerization reaction and the aqueous polymer B obtained by the second-stage and subsequent emulsion polymerization reaction is (aqueous polymer A / aqueous polymer B) is 0.00. It must be 5 / 99.5 to 99.5 / 0.5. However, when the emulsion polymerization reaction has three or more stages, the mass of the aqueous polymer B means the total mass of the aqueous polymer constituting the core layer obtained by the emulsion polymerization reaction after the second stage. When the ratio of the aqueous polymer A used for the first stage emulsion polymerization exceeds 99.5% by mass, the water resistance of the coating film formed by the aqueous emulsion is lowered. On the other hand, when the proportion of the aqueous polymer A is less than 0.5% by mass, the stability of the emulsion polymerization liquid containing the aqueous polymer A used in the emulsion polymerization reaction in the second and subsequent stages is deteriorated. In the resulting aqueous emulsion, agglomeration of aqueous polymer particles is likely to occur, and the strength of the coating film formed by the aqueous emulsion may be reduced, or frost damage due to poor film forming properties may be reduced.

(Physical properties of aqueous polymer particles)
The aqueous polymer particles having the core-shell structure composed of the shell layer made of the aqueous polymer A and the core layer made of the aqueous polymer B described above must satisfy the following conditions (1) to (2). is there.
(1) Glass transition temperature (Tg) of aqueous polymer B forming the core layer ≧ Glass transition temperature (Tg) of aqueous polymer A constituting the shell layer
(2) Glass transition temperature (Tg) of aqueous polymer particles ≧ minimum film forming temperature (MFT) of aqueous polymer particles (provided that the film forming aid is not included in the aqueous polymer particles)

  When the aqueous polymer particles in the aqueous emulsion satisfy the above requirements, the coating film formed by the aqueous emulsion of the present embodiment has excellent coating properties (particularly adhesion, water resistance, warm water resistance, (Water permeability resistance). The reason will be described later.

[2. Aqueous dispersion medium]
The aqueous emulsion of the present embodiment is characterized in that the above-mentioned aqueous polymer particles are emulsified and dispersed in an aqueous dispersion medium. Examples of the aqueous dispersion medium include water, a mixed solvent obtained by mixing water with alcohol (for example, methanol, ethanol, etc.), and a water-soluble solvent such as alcohol and glycol ethers, and is selected from these groups. One or more can be used.

[3. Emulsification / Dispersion]
Further, the aqueous emulsion of the present embodiment is characterized in that the above-mentioned aqueous polymer particles are emulsified and dispersed in the above-described aqueous dispersion medium. Examples of the method for emulsifying and dispersing the aqueous polymer particles include known emulsion polymerization reactions.

[4. Other ingredients]
Within the scope of the present embodiment, a surfactant or a polymerization initiator may be used in the emulsion polymerization reaction of the first stage and / or the second stage or later. Examples of the surfactant include sodium oleate, sodium lauryl sulfate, alkylbenzene sulfonate, alkyl lauryl sulfate benzene sulfonate, alkyl naphthalene sulfonate, alkane sulfonate, dialkyl sulfosuccinate, alkyl phosphate ester salt, Naphthalenesulfonic acid formalin condensate, polyoxyethylene alkyl phenyl ether sulfate ester salt, polyoxyethylene alkyl sulfate ester salt and the like can be mentioned, and one or more selected from these groups can be used. As said surfactant, the reactive surfactant which has 1 or more of radically polymerizable unsaturated groups in a molecule | numerator may be included. The use ratio of the surfactant used in the first and / or second emulsion polymerization is 0.3 to 15.0 parts by mass with respect to 100 parts by mass of all monomers constituting the aqueous polymer particles. Preferably there is. When the amount used is less than 0.3 parts by mass, the stability of the polymerization solution during the first and / or second emulsion polymerization may be reduced, or aggregates of polymer particles may be generated. On the other hand, when the usage-amount is more than 15.0 mass parts, the water resistance of the coating film formed with the obtained water-based emulsion may fall.

  The polymerization initiator is not particularly limited as long as it has the ability to initiate radical polymerization, and examples thereof include a water-soluble polymerization initiator and an oil-soluble polymerization initiator. Specific examples of the water-soluble polymerization initiator include conventionally known water-soluble polymerization initiators such as ammonium persulfate, potassium persulfate, sodium persulfate, and 2,2-azobis (2-amidinopropane) dihydrochloride. . These water-soluble polymerization initiators can be used alone as thermal decomposition polymerization initiators, and these water-soluble polymerization initiators and oil-soluble polymerization initiators are used as oxidizing agents together with various reducing agents. It can also be used as a redox polymerization initiator in combination.

  When the water-soluble polymerization initiator is used alone as a thermal decomposition-type water-soluble polymerization initiator, the amount used is 0.01 to 5.0 with respect to 100 parts by mass of all monomers constituting the aqueous polymer particles. It is preferable that it is a mass part. When the amount of the water-soluble polymerization initiator used is less than 0.01 parts by mass, the unreacted monomer (monomer) remains without completing the reaction during the first and / or second emulsion polymerization. there is a possibility. On the other hand, when the usage-amount is more than 5.0 mass parts, the water resistance / warm water resistance of the coating film formed with the obtained water-based emulsion of this Embodiment may fall.

  On the other hand, by using a water-soluble polymerization initiator or oil-soluble initiator as an oxidizing agent and combining it with various reducing agents, it can be used as a redox polymerization initiator to accelerate the emulsion polymerization rate or emulsion polymerization at a low temperature. It becomes easy to carry out the reaction. Examples of the reducing agent used in combination with the above polymerization initiator as a redox polymerization initiator include reducing organic compounds such as metal salts such as ascorbic acid, tartaric acid and citric acid, sodium thiosulfate, sodium sulfite, and bisulfite. A reducing inorganic compound such as sodium can be used. The oxidizing agent and the reducing agent constituting the redox polymerization initiator described above are each 0.01 to 5.0 parts by mass and 0.01 parts by mass with respect to 100 parts by mass of all monomers constituting the aqueous polymer particles. It is preferable that it is -5.0 mass parts. In the case of redox polymerization using a redox polymerization initiator, a higher molecular weight polymer (polymer) is produced compared to thermal decomposition polymerization using a water-soluble polymerization initiator as a thermal decomposition water-soluble polymerization initiator. Therefore, the coating film formed by using the aqueous emulsion of the present embodiment obtained thereby exhibits better blocking resistance, water resistance, warm water resistance, water permeability and weather resistance. This is preferable.

  In addition, it is preferable that the polymerization temperature at the time of superposing | polymerizing using an above-described polymerization initiator shall be more than the decomposition temperature of each polymerization initiator. For example, in the case of a peroxide polymerization initiator that is a water-soluble polymerization initiator, the temperature may be usually 70 to 90 ° C., and in the case of the above-described redox polymerization initiator, the temperature may be 40 to 90 ° C. Further, the polymerization time is not particularly limited, but it may be usually 2 to 24 hours.

[5. Characteristic]
The aqueous emulsion of the present embodiment has excellent coating properties (particularly adhesion, water resistance, warm water resistance, and water permeability resistance). In particular, the water-based emulsion according to the present embodiment has a water permeation amount of less than 1,500 (ml / m ² · 24 h) measured in an evaluation test described later of a film formed using this as an aqueous coating agent. And water resistance can be improved. The reason will be described below. As described above, the aqueous emulsion of the present embodiment can be obtained by two or more stages of the emulsion polymerization reaction, but the aqueous polymer A obtained by the first stage of polymerization is in the first stage of the emulsion polymerization reaction. , And / or after the first-stage emulsion polymerization reaction, the carboxyl group derived from the carboxyl group-containing ethylenically unsaturated monomer (a2) is neutralized by a basic compound or the like, so that the surface acid value is high and hydrophilic. It will be something. Compared to the aqueous polymer A, the monomer used in the emulsion polymerization reaction in the second and subsequent stages is hydrophobic, so that it can easily enter the aqueous polymer A. The polymer A is polymerized inside the polymer A to form an aqueous polymer B, and the aqueous polymer particles of the present invention are obtained. The MFT of the aqueous polymer particles thus obtained depends on the composition of the aqueous polymer A. If the composition of the aqueous polymer A is hard, the MFT tends to be high, and if it is soft, the MFT tends to be low. There is. On the other hand, the MFT of the aqueous polymer particles is not affected by the aqueous polymer B obtained by the emulsion polymerization reaction after the second stage. Therefore, if the composition of the aqueous polymer A constituting the shell layer is designed to be a soft composition, the composition of the aqueous polymer B obtained by the emulsion polymerization reaction in the second and subsequent stages is hard, or the aqueous polymer particles Even if the composition is hard as a whole, the MFT of the finally obtained aqueous polymer particles can be lowered. Such an aqueous emulsion in which aqueous polymer particles having a low MFT are emulsified and dispersed has sufficient film-forming properties and coating properties (especially adhesion, water resistance, warm water resistance, even if the composition is hard as a whole.・ Water resistance) and can be used for various purposes.

[6. Application]
Since the aqueous emulsion of the present embodiment has the above-mentioned characteristics, for example, general adhesives, adhesives, coating agents, residential building materials, paints, civil engineering / fiber / paper processing, steel plate processing, film coating, etc. In particular, the aqueous emulsion according to the present embodiment is excellent in adhesion, water resistance, warm water resistance, blocking resistance, water resistance, weather resistance, and cost merit. Excellent effects are expected as exterior building materials.

  The aqueous coating agent as described above is sufficiently practical even with the aqueous emulsion of the present embodiment alone, but the aqueous polymer particles contained in the aqueous emulsion obtained by the present embodiment are used in 100 parts by mass. On the other hand, it becomes more excellent by containing 0 to 20 parts by mass of a film-forming auxiliary and 0 to 300 parts by mass of a pigment as necessary.

  Moreover, the aqueous coating agent as described above can provide an excellent inorganic material exterior building material by applying it together with the aqueous emulsion obtained by the present embodiment. Examples of such inorganic material exterior building materials include exterior coatings such as building exterior coatings and exterior exterior coatings used in so-called wet construction methods and dry construction methods.

  The above building exterior coating agent is used in a so-called dry method. For example, a cement raw material and a fiber raw material are molded as a main raw material such as a ceramic siding board. Examples include sealer agents (including inline sealers) and enamel clear top agents used for finishing hardened outer walls. When the aqueous emulsion obtained according to the present embodiment is used as a sealer agent, the film forming property is improved, the blocking resistance is improved, the water permeability is improved, the coating strength is improved, and the amount of the film forming auxiliary agent is reduced. Such an effect is preferable. On the other hand, when it is used as an enamel clear top agent, weather resistance is improved and styrene (styrene resin), which has not been able to be used so far because it works against weather resistance at a low cost, is an aqueous emulsion. It is preferable because it can be contained in the aqueous polymer particles as a constituent component of the material, and both weather resistance and cost reduction can be achieved.

  The above-mentioned paint for exterior buildings (particularly for exterior wall surfaces) is a so-called wet method in which the aqueous emulsion according to the present embodiment and a material such as mortar are mixed and used on a base or an old paint base. It is a paint used in. When the aqueous emulsion obtained according to the present embodiment is used as an exterior paint, it is preferable because of the effects of improving adhesion to a base material of a building or a top coat paint and improving water resistance.

II. Method for Producing Aqueous Emulsion The method for producing an aqueous emulsion according to this embodiment obtains an aqueous emulsion in which aqueous polymer particles having a core-shell structure are emulsified and dispersed in an aqueous dispersion medium by two or more stages of emulsion polymerization reaction. It is a method for producing an aqueous emulsion. Specifically, as an emulsion polymerization reaction in the first stage, 80.0 to 99.5% by mass of a carboxyl group-free ethylenically unsaturated monomer (a1) and a carboxyl group-containing ethylenic monomer in an aqueous dispersion medium. A mixture of monomers containing 0.5 to 20.0% by mass of the unsaturated monomer (a2) is subjected to an emulsion polymerization reaction, and during the first stage emulsion polymerization reaction and / or the first stage emulsion polymerization reaction. Later, by neutralizing the carboxyl group derived from the carboxyl group-containing ethylenically unsaturated monomer (a2) with a basic compound, the aqueous polymer A constituting the shell layer of the core-shell structure of the aqueous polymer particles is obtained. It has the process (henceforth "the process of obtaining the aqueous polymer A") obtained. Furthermore, as a second stage emulsion polymerization reaction, a mixture of monomers containing a carboxyl group-free ethylenically unsaturated monomer (b1) is subjected to an emulsion polymerization reaction in the presence of the aqueous polymer A constituting the shell layer. Then, the step of obtaining the aqueous polymer B constituting the core layer of the core-shell structure of the aqueous polymer particles and, if necessary, the second-stage emulsion polymerization reaction are repeated as the third-stage and subsequent emulsion polymerization reactions. And a step of obtaining an aqueous polymer constituting the third and subsequent core layers of the core-shell structure of the aqueous polymer particles (hereinafter referred to as “step of obtaining aqueous polymer B”). To do. The aqueous polymer A constituting the shell layer obtained by the first emulsion polymerization reaction has a glass transition temperature of −40 ° C. to 80 ° C. and a weight average molecular weight of 50,000 or more, A milky white emulsion is formed without being solubilized after neutralization of the group, and the aqueous polymer B obtained by the emulsion polymerization reaction in the second and subsequent stages has a glass transition temperature of 0 ° C. to 120 ° C. Yes, the mass ratio of aqueous polymer A to aqueous polymer B (aqueous polymer A / aqueous polymer B) is 0.5 / 99.5 to 99.5 / 0.5 (however, emulsion polymerization) When the reaction has three or more stages, the mass of the aqueous polymer B means the total mass of the aqueous polymer constituting the core layer) and the following conditions (1) to (2) are satisfied. . Preferably, the following condition (3) is further satisfied.
(1) Glass transition temperature of aqueous polymer B forming the core layer ≧ glass transition temperature of aqueous polymer A constituting the shell layer (2) Glass transition temperature of aqueous polymer particles ≧ minimum film formation of aqueous polymer particles Temperature (however, when water-soluble polymer particles do not contain a film-forming aid)
(3) The pH after neutralizing the carboxyl group of the aqueous polymer A constituting the shell layer is 5.0 to 10.0, and the absorbance after neutralization is relative to the absorbance before neutralization. It is a ratio of 99.5-40% Hereinafter, each process of the manufacturing method of the water-based emulsion of this Embodiment is demonstrated concretely.

[1. Step of obtaining aqueous polymer A]
In the method for producing an aqueous emulsion of the present embodiment, the carboxyl group-free ethylenically unsaturated monomer (a1) and the carboxyl group-containing ethylenically unsaturated monomer (a2) are used as the first stage emulsion polymerization reaction. And a mixture of monomers containing a carboxyl group-containing ethylenically unsaturated monomer with a basic compound during and / or after the first emulsion polymerization reaction. It is necessary to obtain a milky white emulsion containing the aqueous polymer A constituting the shell layer by neutralizing the carboxyl group derived from (a2). In the first-stage emulsion polymerization reaction, it is not essential to polymerize all monomers, and the process may proceed to the next step before all the monomers are polymerized (pre-polymerized state). .

  The carboxyl group-free ethylenically unsaturated monomer (a1) used in the first emulsion polymerization reaction of the method for producing an aqueous emulsion of the present embodiment has 1 to 12 carbon atoms in the alkyl group ( (Meth) acrylic acid alkyl ester monomers (including cyclic alkyl esters), vinyl group-containing monomers, hydroxyl group-containing unsaturated monomers, amide group-containing unsaturated monomers, alkoxysilyl group-containing unsaturated monomers And one or more monomers selected from the group consisting of a piperidyl group-containing unsaturated monomer. Since these specific examples and details of the amount used have been described above, they will be omitted.

  The carboxyl group-containing ethylenically unsaturated monomer (a2) used in the first emulsion polymerization reaction of the method for producing an aqueous emulsion of the present embodiment is (meth) acrylic acid, maleic anhydride, and itaconic acid. One or more monomers selected from the group consisting of: Since these specific examples and details of the amount used have been described above, they will be omitted.

  The aqueous polymer A thus obtained needs to have a glass transition temperature of −40 ° C. to 80 ° C. and a weight average molecular weight of 50,000 or more.

  By using a basic compound during the first stage emulsion polymerization reaction and / or after the first stage emulsion polymerization reaction of the method for producing an aqueous emulsion according to the present embodiment, the carboxyl group-containing ethylenically unsaturated monomer is used. By neutralizing the carboxyl group derived from the monomer (a2), an aqueous polymer A having hydrophilicity can be obtained. By neutralizing the carboxyl group derived from the carboxyl group-containing ethylenically unsaturated monomer (a2), which is a constituent of the aqueous polymer A, the aqueous polymer A is a kind having a hydrophilic part and a hydrophobic part. It can act as a polymer emulsifier. By using the emulsion polymerization liquid containing such an aqueous polymer A in the emulsion polymerization reaction of the aqueous polymer B constituting the core layer described later, the reaction can be performed more stably. And when the carboxyl group which the aqueous polymer A which comprises a shell layer has neutralized, since orientation of carboxylic acid to particle | grain surface becomes strong, it was obtained by the manufacturing method of the aqueous emulsion of this Embodiment. A coating film formed using an aqueous emulsion has excellent water permeability and moisture resistance.

  The basic compound is preferably, for example, one or more compounds selected from the group consisting of amine compounds (including amino alcohol and ammonia), sodium hydroxide, and potassium hydroxide. Specific examples of the amine compound include those described above. The amount of the basic compound used is preferably an amount such that the pH of the emulsion polymerization solution after neutralization is 5.0 to 10.0. If pH is in the range of 5.0-10.0, the emulsion polymerization reaction of the aqueous polymer B which comprises a core layer can be performed stably.

  The emulsion polymerization solution containing the aqueous polymer A obtained by neutralization with the basic compound is a milky white emulsion polymer (alkali swelled neutralized product) that is not solubilized. If the aqueous polymer A is dissolved after neutralization to form a water-soluble resin solution, the water resistance of the shell layer is lowered, and the water permeability and water resistance of the coating film formed by the aqueous emulsion obtained are reduced. May decrease. In addition, when a chain transfer agent is used for the first stage emulsion polymerization reaction, the aqueous polymer A obtained after neutralization is easily solubilized and becomes an aqueous resin solution. It is preferable not to use a chain transfer agent, but a chain transfer agent may be used as long as the aqueous polymer A is not solubilized (absorbance ratio 99.5 to 40.0%).

Furthermore, the absorbance of the emulsion polymerization solution containing the aqueous polymer A obtained by neutralization with the basic compound is 99.5 to 40% (absorbance ratio) with respect to the absorbance of the emulsion polymerization solution before neutralization. Preferably there is. When the absorbance ratio is lower than 40%, the water resistance of the coating film formed by the finally obtained aqueous emulsion is lowered. When the absorbance ratio is in the above range, the emulsion polymerization liquid containing the aqueous polymer A becomes a milky white emulsion that is not solubilized. The absorbance ratio is determined from the following formula.
Absorbance ratio (%) = first emulsion polymerization solution (after neutralization with aqueous ammonia) / first emulsion polymerization solution (before neutralization with aqueous ammonia) × 100

[2. Step of obtaining aqueous polymer B]
In the method for producing the aqueous emulsion of the present embodiment, after obtaining the aqueous polymer A constituting the shell layer as described above, as the second stage emulsion polymerization reaction, a carboxyl group is present in the presence of the aqueous polymer A. A mixture of monomers containing the non-containing ethylenically unsaturated monomer (b1) is subjected to an emulsion polymerization reaction to polymerize the aqueous polymer B constituting the core layer of the core-shell structure of the aqueous polymer particles. Accordingly, as the emulsion polymerization reaction after the third stage, the above-mentioned second stage emulsion polymerization reaction is repeated to form the third and subsequent core layers of the core-shell structure of the aqueous polymer particles. It is necessary to obtain aqueous polymer particles by polymerizing. Hereinafter, the aqueous polymer B obtained by the second-stage emulsion polymerization reaction and the aqueous polymer obtained by the third-stage and subsequent emulsion polymerization reaction are collectively referred to as “aqueous polymer B”, and the emulsion to obtain these The polymerization reaction is collectively referred to as “emulsion polymerization reaction after the second stage”. In the second and subsequent emulsion polymerizations, it is not essential to polymerize all monomers, and the process may proceed to the next step before all of the monomers are polymerized (pre-polymerized state). .

  As the carboxyl group-free ethylenically unsaturated monomer (b1) used in the emulsion polymerization reaction in the second and subsequent stages of the method for producing the aqueous emulsion of the present embodiment, the carboxyl group-free ethylenic monomer described above is used. The compound similar to an unsaturated monomer (a1) can be mentioned. Moreover, the carboxyl group-containing ethylenically unsaturated monomer (a2) demonstrated previously can be used as another monomer component.

  The aqueous polymer B thus obtained is characterized in that the glass transition temperature thereof is 0 ° C to 120 ° C.

  Moreover, in the manufacturing method of the aqueous emulsion of this Embodiment, mass ratio (aqueous polymer A / aqueous polymer B) of the aqueous polymer A and the aqueous polymer B is 0.5 / 99.5-99. .5 / 0.5. However, when the emulsion polymerization reaction has three or more stages, the mass of the aqueous polymer B means the total mass of the aqueous polymer constituting the core layer.

Moreover, in the manufacturing method of the water-based emulsion of this Embodiment, it is required to satisfy the following conditions (1)-(2), and it is preferable to satisfy the following conditions (3).
(1) Glass transition temperature of aqueous polymer B forming the core layer ≧ glass transition temperature of aqueous polymer A constituting the shell layer (2) Glass transition temperature of aqueous polymer particles ≧ minimum film formation of aqueous polymer particles Temperature (however, when water-soluble polymer particles do not contain a film-forming aid)
(3) The pH after neutralizing the carboxyl group of the aqueous polymer A constituting the shell layer is 5.0 to 10.0, and the absorbance after neutralization is relative to the absorbance before neutralization. The ratio should be 99.5-40%

III. Aqueous Coating Agent Film The aqueous coating agent film of the present embodiment was formed using the aqueous emulsion of the present embodiment described above or the aqueous emulsion obtained by the method for producing the aqueous emulsion of the present embodiment described above. The water permeability of the film is less than 1,500 (ml / m ² · 24 h). When the water permeation amount of the film satisfies the above, it is possible to provide a film having excellent water permeation resistance. The reason is omitted because it has been described above.

  Next, the aqueous emulsion of the present invention and the production method thereof will be described more specifically with reference to examples and comparative examples. In the text, “part” and “%” are based on mass.

[Example 1]
(Preparation of milky white emulsion containing aqueous polymer A)
14.7 parts of ion-exchanged water, as an emulsifier, 3.4 parts of sodium polyoxyethylene alkyl ether sulfate (manufactured by Kao Corporation, trade name: Latemul E-118B), ammonium polyoxyalkylene alkenyl ether sulfate (manufactured by Kao Corporation, trade name: (Latemul PD-104) 4.4 parts, (a1) component, 2-hydroxyethyl acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: light ester HOA) 0.97 parts, 2-ethylhexyl acrylate 19.42 parts, methyl 4.85 parts of methacrylate, 9.71 parts of styrene, 1.94 parts of acrylic acid (100%) as a component (a2) are weighed and stirred to mix the monomers constituting the aqueous polymer A Liquid (1) was prepared.

  A reactor equipped with a stirrer, reflux condenser, thermometer, dropping device and nitrogen gas introduction tube was charged with 67.3 parts of ion exchange water and sodium polyoxyethylene alkyl ether sulfate (trade name: Latemul E-118B, manufactured by Kao Corporation). ) 0.4 parts was charged, and the air in the reaction apparatus was replaced with nitrogen gas, and then the internal temperature of the apparatus was heated to 80 ° C. while stirring. Next, 4.0 parts of 5% ammonium persulfate (trade name: ammonium persulfate, manufactured by Mitsubishi Gas Chemical Co., Inc.) was added to the reactor, and immediately after the emulsion mixture (1) prepared previously and 5% ammonium persulfate 2. 0 parts were added dropwise over 1.5 hours. And 30 minutes after completion | finish of dripping, after adding 1.5 parts of ammonia water (25%), it was left to stand at 80 degreeC for 30 minutes, and the milky white emulsion containing the aqueous polymer A was obtained.

(Preparation of aqueous emulsion containing aqueous polymer particles)
Next, 24.6 parts of ion-exchanged water, 6.2 parts of polyoxyethylene alkyl ether sodium sulfate (trade name: Latemul E-118B) as an emulsifier, polyoxyalkylene alkenyl ether ammonium sulfate (manufactured by Kao Corporation, Product name: LATEMUL PD-104) Along with 8.1 parts, as a component (b1), 4.86 parts of 2-ethylhexyl acrylate and 58.25 parts of styrene are weighed and stirred to form an aqueous polymer B An emulsified mixed liquid (2) in which the body was mixed was prepared.

  And 60 minutes after completion | finish of dripping of the emulsification liquid mixture (1), the emulsification liquid mixture (2) prepared above and 2.0 parts of 5% ammonium persulfate were dripped in the apparatus over 3.0 hours. And after reacting for further 3 hours, keeping the internal temperature of the said apparatus at 80 degreeC, internal temperature is cooled to room temperature and the aqueous | water-based emulsion of Example 1 containing the aqueous polymer particle which has a core-shell structure is obtained. Obtained. As a result of analysis, the obtained aqueous emulsion had a viscosity of 700 mPa · s / 25 ° C., a solid content of 44.0%, a pH of 8.5, and an average particle size of 150 nm.

[Examples 2 to 6]
In the same manner as in Example 1, except that the monomer component (a1, a2, b1) and additive compounding amount in Example 1 were changed to those shown in Table 1, Examples 2-6 An aqueous emulsion was made. However, since it is multistage emulsion polymerization, the amounts of polymerization initiator and surfactant were divided and used according to the monomer ratio. The monomer constituents and special values of the obtained aqueous emulsions of Examples 2 to 6 are shown in Table 1 together with the monomer constituent components and special values of the aqueous emulsion of Example 1. In addition, the viscosity, solid content, pH, and average particle diameter of the obtained aqueous emulsion were adjusted to be substantially the same as in Example 1.

[Comparative Examples 1-4]
Example 1 except that the monomer constituents (a1, a2, b1), additives, use amount of the neutralizing agent, timing of using the neutralizing agent, etc. in Example 1 were changed to those shown in Table 1. In the same manner, aqueous emulsions of Comparative Examples 1 to 4 were prepared. However, since it is multistage emulsion polymerization, the amounts of polymerization initiator and surfactant were divided and used according to the monomer ratio. Table 1 shows the monomer constituents and special values of the obtained aqueous emulsions of Comparative Examples 1 to 4 together with the monomer constituents and special values of the aqueous emulsion of Example 1.

[Evaluation]
Using the aqueous emulsions prepared in Examples 1 to 6 and Comparative Examples 1 to 4, each sample was prepared with the formulation described in Tables 2 to 5, and using this, an evaluation test [warm water resistance test described later] , Adhesion test, water permeation resistance test (above, for dry construction method), adhesion test, water resistance / adhesion test (above, for wet construction method)].
1. Preparation of sample for evaluation Using the aqueous emulsions prepared in Examples 1 to 6 and Comparative Examples 1 to 4, a sample of an exterior coating aqueous coating agent for a warm water resistance test of a dry construction method is prepared in the formulation table of Table 2 Then, in Table 3, a sample of an exterior coating aqueous coating agent for a dry method adhesion test is prepared, and in Table 4, a sample of an exterior coating aqueous coating agent for a dry method water permeability test is prepared. A sample of a water-based coating material for exterior paints for water resistance / adhesion test of the wet method was prepared according to the recipe in Table 5.

The mill base 1 in Table 4 was blended at the ratio shown below. The mill base refers to a mixture obtained by stirring and mixing pigments, solvents, additives and the like.
* Millbase 1 prescription (total 100.0 parts)
Water 30.0 parts Dispersant: Demol EP (manufactured by Kao Chemical Co., Ltd.) 2.0 parts Heavy calcium carbonate: Heavy calcium carbonate R (manufactured by Maruo Calcium Co., Ltd.) 48.7 parts Titanium dioxide: CR-57 (manufactured by Ishihara Sangyo Co., Ltd.) 18.3 parts antifoaming agent: Adecanate B-187 (manufactured by ADEKA) 0.5 part ammonia water (25%) 0.5 part

The mill base 2 in Table 5 was blended at the ratio shown below.
* Millbase 2 prescription (total 100.0 parts)
Water 29.0 parts Dispersant: SMA-1440H (manufactured by Sartomer Japan) 10.0 parts Titanium dioxide: CR-57 (manufactured by Ishihara Sangyo Co., Ltd.) 40.0 parts Heavy calcium carbonate: Heavy calcium carbonate (Maruo calcium 20.0 parts Antifoaming agent: Adecanate B-187 (manufactured by ADEKA) 0.5 part Ammonia water (25%) 0.5 part

2. Hot water resistance test (dry method)
A sample of the aqueous coating agent for exterior paints of Examples and Comparative Examples prepared in Table 2 was applied to a glass plate so as to be 100 μWET / m ^2, and then dried for 10 minutes in a hot air circulator at 100 ° C. A coating film was produced on top. And after the temperature of a glass plate and a coating film returned to room temperature, this was immersed in warm water (60 degreeC), and was left to stand for 24 hours. And the (DELTA) E value of the coating film surface 24 hours after being immersed in warm water was measured, and the following references | standards evaluated. In addition, (circle)-(triangle | delta) was set as the pass and x was set as the disqualified point.
<Evaluation criteria>
○: The ΔE value of the coating film was 0 to less than 3.
Δ: The ΔE value of the coating film was 3 or more and less than 10.
X: The ΔE value of the coating film was 10 or more.

3. Adhesion test (dry method)
After diluting samples of waterborne coating agents for exterior paints of Examples and Comparative Examples prepared in Table 3 with water to 10%, applying 150 μWET / m ^{2 on} a slate plate using a sponge roll coater, 100 ° C. The sample was dried with a hot air circulator for 15 minutes to prepare a sample on which a sample coating film was formed. And after the temperature of the sample returned to room temperature, the coating film peeling area rate (%) P was calculated | required and evaluated by the method based on JISA5422 using this. In addition, the coating film peeling area ratio (%) calculated from the following formula was accepted as less than 5%, and those exceeding it were regarded as unacceptable.
P (peeling film peeling area ratio (%)) = S2 (peeling film peeling area (mm ² )) / S1 (attached tape area (mm ² )) × 100

4). Water permeability test (dry method)
Samples of the aqueous coating agents for exterior paints of Examples and Comparative Examples prepared in Table 4 were diluted with water so as to be 10%, and after applying 150 g WET / m ² to a siding board using a sponge roll coater, 100 ° C. Was dried for 15 minutes with a hot air circulator to prepare a board sample on which a coating film was formed. And the board | substrate sample calculated | required the water reduction height by the method based on JISA5422, and also calculated | required the water permeability (ml / m < ² > * 24h) after 24 hours. In addition, less than 1,500 (ml / m ² · 24h) was accepted, and 1,500 (ml / m ² · 24h) or more was rejected.

5. Adhesion test (wet method)
In advance, 100 g WET / m ² of “One-part-penetration sealer” (manufactured by Nippon Paint Co., Ltd.) was applied to a flexible plate (JIS A5430 compliant) and allowed to stand in an atmosphere of 23 ° C. × 50% for 24 hours. And after apply | coating the sample of the coating agent for exterior paints of the Example and comparative example which were prepared in Table 5 to the flexible board which carried out the sealer process previously so that it might be set to 150 gWET / m < ² >, in 23 degreeC x 50% atmosphere Was cured for 7 days to produce an adhesion test plate. And it evaluated by the method based on JISK5600-5-6 (cross-cut method) in the following six steps. In addition, the classification 0 to the classification 1 was set as the pass, and the classification 2 or less was set as the rejection.

<Evaluation criteria>
-Classification 0: There was no peeling in the eyes of any lattice.
-Classification 1: There was a small peeling of the coating film at the intersection of the cut, and the peeling of the cross cut part was 5% or less.
Classification 2: The coating film was peeled along the edge of the cut and / or at the intersection, and the peeling of the crosscut portion was more than 5% and less than 15%.
Classification 3: The coating film was largely peeled along the edges of the cut, and the peeling of the crosscut portion was 15% or more and less than 35%.
Classification 4: The coating film was largely peeled along the edge of the cut, and the cross-cut part was 35% or more.
・ Category 5: There was peeling more than classification 4.

6). Water resistance and adhesion test (wet method)
Prepared by pre-applying “One-part-penetration sealer” (manufactured by Nippon Paint Co., Ltd.) to 100 g WET / m ^{2 on a} flexible plate (JIS A5430 compliant) and then leaving it in an atmosphere of 23 ° C. × 50% for 24 hours. did. And after apply | coating the sample of the coating agent for exterior paints of the Example and comparative example which were prepared in Table 5 to the above-mentioned flexible board which carried out the sealer process so that it might be set to 150 gWET / m < ² >, it was 23 degreeC x 50% of atmosphere. For 7 days to prepare a water resistance / adhesion test plate. Thereafter, the test plate was immersed in water at 20 ° C. for 7 days. And the state of the coating-film surface was observed within 30 minutes after taking out and washing with water, and it evaluated visually by the following reference | standard. In addition, (double-circle) and (circle) were set as the pass, and (triangle | delta) or less was set as the failure.

<Evaluation criteria>
A: The coating film soaked in water did not swell, peel off or crack.
○: The coating film soaked in water had swelling, peeling, cracking, etc. with an area of less than 5%.
(Triangle | delta): The coating film immersed in water had the swelling of 5% or more and less than 20%, a peeling, a crack, etc.
X: The coating film immersed in water had swelling, peeling, cracking, etc. of an area of 20% or more.

  According to the present invention, it is an aqueous emulsion capable of forming a coating film having excellent film forming properties and coating film characteristics, and particularly excellent in adhesion to an exterior wall surface of a building or a ceramic siding board. A water-based emulsion that can be formed as a coated film is provided. In particular, the water-based emulsion of the present invention exhibits excellent adhesion, water resistance, hot water resistance, and water permeability when a coating film is formed, so that it is a sealer agent for exterior wall surfaces of buildings and ceramic siding boards. It is useful as an enamel clear top agent and paint.

Claims (10)

An aqueous emulsion obtained by emulsifying and dispersing aqueous polymer particles in an aqueous dispersion medium,
The aqueous polymer particles have a core-shell structure obtained by an emulsion polymerization reaction of two or more stages.
The core-shell structure is composed of a shell layer made of an aqueous polymer A and a core layer made of an aqueous polymer B,
The aqueous polymer A constituting the shell layer is composed of 80.0 to 99.5% by mass of a carboxyl group-free ethylenically unsaturated monomer (a1) as a constituent component and a carboxyl group-containing ethylenically unsaturated monomer. In addition to containing 0.5 to 20.0% by mass of the body (a2), the carboxyl group derived from the carboxyl group-containing ethylenically unsaturated monomer (a2) is neutralized, and the glass transition temperature is −40 ° C. to At 80 ° C. and a weight average molecular weight of 50,000 or more,
The aqueous polymer B constituting the core layer contains a carboxyl group-free ethylenically unsaturated monomer (b1) as a component, and has a glass transition temperature of 0 ° C. to 120 ° C.,
The mass ratio of the aqueous polymer A and the aqueous polymer B (aqueous polymer A / aqueous polymer B) is 0.5 / 99.5 to 99.5 / 0.5 (however, the emulsification) When the polymerization reaction is three or more stages, the mass of the aqueous polymer B means the total mass of the aqueous polymer constituting the core layer), and
An aqueous emulsion characterized by satisfying the following conditions (1) to (2).
(1) Glass transition temperature of the aqueous polymer B forming the core layer ≧ glass transition temperature of the aqueous polymer A constituting the shell layer (2) Glass transition temperature of the aqueous polymer particles ≧ the aqueous weight Minimum film-forming temperature of coalesced particles (provided that the film-forming aid is not included in the aqueous polymer particles)   The carboxyl group-free ethylenically unsaturated monomer (a1) is a (meth) acrylic acid alkyl ester monomer (including a cyclic alkyl ester) having an alkyl group having 1 to 12 carbon atoms, a vinyl group-containing monomer. One or more monomers selected from the group consisting of a monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, an alkoxysilyl group-containing unsaturated monomer, and a piperidyl group-containing unsaturated monomer. The aqueous emulsion according to claim 1 which is a monomer.   The carboxyl group-containing ethylenically unsaturated monomer (a2) is one or more monomers selected from the group consisting of (meth) acrylic acid, maleic anhydride, and itaconic acid. The aqueous emulsion as described. The water-based emulsion according to claim 1, wherein the formed coating film has a water permeability of less than 1,500 (ml / m ² · 24 h). An aqueous emulsion production method for obtaining an aqueous emulsion in which aqueous polymer particles having a core-shell structure are emulsified and dispersed in an aqueous dispersion medium by two or more stages of emulsion polymerization reaction,
As an emulsion polymerization reaction in the first stage, 80.0 to 99.5% by mass of a carboxyl group-free ethylenically unsaturated monomer (a1) and a carboxyl group-containing ethylenically unsaturated monomer in an aqueous dispersion medium. A mixture of monomers containing 0.5 to 20.0% by mass of (a2) is subjected to an emulsion polymerization reaction, and during the first emulsion polymerization reaction and / or after the first emulsion polymerization reaction, An aqueous polymer A constituting the shell layer of the core-shell structure of the aqueous polymer particles by neutralizing the carboxyl group derived from the carboxyl group-containing ethylenically unsaturated monomer (a2) with a functional compound. Obtaining a step;
As a second-stage emulsion polymerization reaction, a mixture of monomers containing a carboxyl group-free ethylenically unsaturated monomer (b1) is subjected to an emulsion polymerization reaction in the presence of the aqueous polymer A constituting the shell layer. Obtaining an aqueous polymer B constituting the core layer of the core-shell structure of the aqueous polymer particles;
If necessary, as the emulsion polymerization reaction after the third stage, the second stage emulsion polymerization reaction is repeated to form the aqueous layer constituting the third and subsequent core layers of the core-shell structure of the aqueous polymer particles. Obtaining a polymer, and
The aqueous polymer A constituting the shell layer obtained by the first emulsion polymerization reaction has a glass transition temperature of −40 ° C. to 80 ° C. and a weight average molecular weight of 50,000 or more. And forming a milky white emulsion without being solubilized after neutralization of the carboxyl group,
Each of the aqueous polymers B obtained by the emulsion polymerization reaction after the second stage has a glass transition temperature of 0 ° C to 120 ° C,
The mass ratio of the aqueous polymer A and the aqueous polymer B (aqueous polymer A / aqueous polymer B) is 0.5 / 99.5 to 99.5 / 0.5 (however, the emulsification) When the polymerization reaction has three or more stages, the mass of the aqueous polymer B means the total mass of the aqueous polymer constituting the core layer), and the following conditions (1) to (2) are satisfied. A method for producing an aqueous emulsion.
(1) Glass transition temperature of the aqueous polymer B forming the core layer ≧ glass transition temperature of the aqueous polymer A constituting the shell layer (2) Glass transition temperature of the aqueous polymer particles ≧ the aqueous weight Minimum film-forming temperature of coalesced particles (provided that the film-forming aid is not included in the aqueous polymer particles)   Furthermore, condition (3) pH after neutralizing the carboxyl group of the aqueous polymer A constituting the shell layer is 5.0 to 10.0, and the absorbance after neutralization is the absorbance before neutralization. The manufacturing method of the water-based emulsion of Claim 5 which satisfy | fills that it is a ratio of 99.5-40% with respect to.   The carboxyl group-free ethylenically unsaturated monomer (a1) is a (meth) acrylic acid alkyl ester monomer (including a cyclic alkyl ester) having an alkyl group having 1 to 12 carbon atoms, a vinyl group-containing monomer. One or more monomers selected from the group consisting of a monomer, a hydroxyl group-containing unsaturated monomer, an amide group-containing unsaturated monomer, an alkoxysilyl group-containing unsaturated monomer, and a piperidyl group-containing unsaturated monomer. The method for producing an aqueous emulsion according to claim 5 or 6, which is a polymer.   The carboxyl group-containing ethylenically unsaturated monomer (a2) is one or more monomers selected from the group consisting of (meth) acrylic acid, maleic anhydride, and itaconic acid. The manufacturing method of the aqueous emulsion of any one of Claims 1.   The basic compound is one or more compounds selected from the group consisting of amine compounds (including amino alcohol and ammonia), sodium hydroxide, and potassium hydroxide. A method for producing an aqueous emulsion as described in 1. above. The film formed using the aqueous emulsion of any one of Claims 1-4, or the aqueous emulsion obtained by the manufacturing method of the aqueous emulsion of any one of Claims 5-9. The water-permeable amount of water is less than 1,500 (ml / m ² · 24h), and is a water-based coating agent film.

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