WO2018110342A1

WO2018110342A1 - Emulsion

Info

Publication number: WO2018110342A1
Application number: PCT/JP2017/043435
Authority: WO
Inventors: 康司壹岐; 田中　陽子
Original assignee: 旭化成株式会社
Priority date: 2016-12-13
Filing date: 2017-12-04
Publication date: 2018-06-21
Also published as: JP6723379B2; JPWO2018110342A1

Abstract

The present invention pertains to an emulsion with which it is possible to form a coating film having exceptional weather resistance, especially gloss retentivity. The present invention is an emulsion that contains water, polymer particles (A) having a glass transition temperature of 10 to 70°C, and polymer particles (B) having a glass transition temperature of -20 to 40°C. The polymer particles (A) are contained within a range of 3-20% by mass relative to the total mass of the polymer particles (A) and polymer particles (B), the volume-average particle diameter ratio of the polymer particles (A) and polymer particles (B) is within the range of 1/30 to 5/6, the zeta potential of the polymer particles (A) is 3 to 25 mV higher than the zeta potential of the polymer particles (B), and the zeta potential of the polymer particles (B) is greater than -54 mV. The polymer particles (A) and/or the polymer particles (B) may have structural units derived from an ethylenic unsaturated monomer.

Description

Emulsion

The present invention relates to an emulsion.

Water-based emulsions obtained by emulsion polymerization are often used as resins for water-based paints because a film formed by drying at room temperature or under heating exhibits relatively good durability. However, compared to solvent-based paints, the initial coating film formed from an emulsion forms particle interfaces and inter-particle spots due to filling and fusion of particles, so there is an absorption path for water molecules from the outside and resistance. This is a factor that reduces the water absorption whitening property. Further, depending on the degree of fusion at the particle interface, the coating film stress is reduced. Due to structural factors during the formation of these coating films, it has been a problem that weather resistance performance cannot be expressed.

As a technique for solving this problem, a method of mixing a plurality of emulsions has been proposed. Patent Documents 1 and 2 disclose coating compositions in which the particle size ratio and glass transition temperature are different and a plurality of emulsion particles having a controlled molecular weight are mixed to reduce the amount of film-forming aid. Patent Document 3 discloses an emulsion composition for a vibration damping material in which two types of emulsion particles having different glass transition temperatures and molecular weights are mixed to improve sagging resistance under conditions where the film thickness is large. ing.

Japanese Patent Laid-Open No. 2001-200181 JP 2006-283029 A JP 2010-53210 A

However, the methods of blending the same type or different types of emulsions that have been proposed in the past often cancel each other's performance, and even with the techniques shown in Patent Documents 1 to 3, the weather resistance is sufficient. I could not say. Accordingly, there is a need for emulsions with further improved weather resistance.
Accordingly, an object of the present invention is to provide an emulsion capable of forming a coating film excellent in weather resistance, particularly gloss retention.

As a result of intensive studies in view of the above circumstances, the present inventor has dispersed polymer particles that are the main component of the coating film and polymer particles that reinforce the interface in an aqueous medium so that the main component when forming the coating film is dispersed. By unevenly distributing polymer particles that reinforce the interface on the outer periphery of the coalesced particles, it is possible to increase the durability of the particle interface in the coating film, which allows water molecules to enter the particle interface and interparticle voids. It was found that an emulsion capable of forming a coating film with excellent weather resistance, particularly gloss retention, was obtained, and the present invention was completed.

That is, the present invention is as follows.
[1].
Water, polymer particles (A) having a glass transition temperature of 10 ° C. to 70 ° C., and polymer particles (B) having a glass transition temperature of −20 ° C. to 40 ° C., the polymer particles (A) being The polymer particles (A) and the polymer particles (B) are contained in the range of 3% by mass to 20% by mass with respect to the total mass of the polymer particles (A) and the polymer particles (B). The zeta potential of the polymer particles (A) is 3 mV or more and 25 mV or less higher than the zeta potential of the polymer particles (B). And the zeta potential of the polymer particles (B) is greater than −60 mV, preferably greater than −54 mV.
[2].
The emulsion according to [1] above, wherein the polymer particles (A) and / or the polymer particles (B) have a structural unit derived from an ethylenically unsaturated monomer.
[3].
The emulsion according to [1] or [2] above, wherein the polymer particles (A) and / or the polymer particles (B) have a structural unit derived from a hydrolytic condensate of an organosilane compound.
[4].
The polymer particle (A) has a structural unit derived from a hydrolytic condensate of an organosilane compound, and the polymer particle (B) has a structural unit derived from an ethylenically unsaturated monomer. The emulsion according to item 3].
[5].
[4] The polymer particle (A) and the polymer particle (B) both have a structural unit derived from an ethylenically unsaturated monomer and a structural unit derived from a hydrolysis condensate of an organosilane compound. The emulsion according to item.
[6].
The ratio of the structural unit derived from the hydrolysis condensate of the organosilane compound to the structural unit derived from the ethylenically unsaturated monomer of the polymer particle (A) is equal to or higher than the ratio of the polymer particle (B). The emulsion according to item 5].
[7].
An emulsion comprising water, polymer particles (A), and polymer particles (B) having a volume average particle size larger than that of the polymer particles (A), wherein ethylene is added to the total solid content of the emulsion. In a STEM dark field image of a coating film formed from a clear paint blended with 10% by mass of glycol monobutyl ether and 20% by mass of texanol, the polymer particles (A) cover the polymer particles (B). Emulsion.
[8].
In a STEM dark field image of a coating film formed from a clear paint in which 10% by mass of ethylene glycol monobutyl ether and 20% by mass of texanol are blended with respect to the total solid content of the emulsion, the polymer particles (A) are The emulsion according to any one of items [1] to [6], which coats the coalesced particles (B).

According to the emulsion of the present invention, it is possible to form a coating film excellent in weather resistance, particularly gloss retention.

The STEM dark field image of the coating-film cross section of Example 2 is shown.

Hereinafter, embodiments for carrying out the present invention will be described in detail. The present invention is not limited to the following embodiments, and can be appropriately modified and implemented within the scope of the gist defined by the claims.

In an exemplary embodiment, the emulsion according to the present invention comprises water, polymer particles (A) having a glass transition temperature of 10 ° C. to 70 ° C., and polymer particles having a glass transition temperature of −20 ° C. to 40 ° C. (B), and the polymer particles (A) in a range of 3% by mass to 20% by mass with respect to the total mass of the polymer particles (A) and the polymer particles (B), Volume average particle size ratio between the polymer particles (A) and the polymer particles (B) (the volume average particle size of the polymer particles (A) with respect to the volume average particle size of the polymer particles (B)) Ratio) is in the range of 1/30 to 5/6, and the zeta potential of the polymer particles (A) is 3 mV to 25 mV higher than the zeta potential of the polymer particles (B), and the weight The zeta potential of the coalesced particles (B) is greater than −60 mV, preferably −54 mV. Ri is a large emulsion.
As will be described in detail later, the polymer particles (B) have a function as polymer particles that are the main component of the coating film, and the polymer particles (A) have a function as polymer particles that reinforce the interface.

Each particle of the emulsion in which the polymer particles (A) and the polymer particles (B) are blended can be separated by adjusting the conditions using a centrifuge.

The polymer particles (A) and (B) are not particularly limited as long as the glass transition temperature, mass ratio, volume average particle size ratio, and zeta potential satisfy the requirements of the above ranges, and the same type and different types of resins. It may be configured with either.
In an exemplary embodiment, the polymer particles (A) and / or the polymer particles (B) (ie, at least one of the polymer particles (A) and the polymer particles (B)) is an ethylenically unsaturated monomer. It has a structural unit derived from a monomer. Although an ethylenically unsaturated monomer is not specifically limited, What is mentioned later regarding manufacture of a polymer particle can be used.
For example, as polymer particles (A) and (B), a high weather resistance (meth) acrylate resin and a general-purpose (meth) acrylate resin using a hydrophobic monomer, a polysiloxane-containing aqueous (meth) acrylate resin and a general-purpose resin (Meth) acrylate resins, polysiloxane-containing aqueous (meth) acrylate resins and highly weather-resistant (meth) acrylate resins, (meth) acrylic composite fluororesins and general-purpose (meth) acrylate resins, polysiloxane-containing aqueous solutions ( Various combinations such as a (meth) acrylate resin and a urethane resin are possible. More specifically, from the viewpoint of compatibility between resins, the combination of the polymer particles (A) and the polymer particles (B) is a (meth) acrylate obtained by an addition polymerization reaction of an ethylenically unsaturated monomer. A polysiloxane-containing aqueous (meth) acrylate resin obtained by addition polymerization reaction of an ethylenic unsaturated monomer and a hydrolytic condensation reaction of an organic silane compound, or each of them It is preferable that the resin is one kind or a combination of plural kinds. The polymer particles (A) may be one kind or a mixture of plural kinds. Further, the polymer particles (B) may be one kind or a mixture of plural kinds.

The emulsion polymerization method of the polymer particles (A) and the polymer particles (B) is not particularly limited, and examples thereof include a method of polymerizing a pre-emulsion liquid containing an ethylenically unsaturated monomer and an emulsifier in an aqueous medium. Moreover, after mixing the pre-emulsion liquid containing an ethylenically unsaturated monomer and an emulsifier and an organosilane compound, polymerization of the ethylenically unsaturated monomer and hydrolysis and condensation reaction of the organosilane compound in an aqueous medium Can be performed simultaneously. In emulsion polymerization, it is preferable to adjust the pH of the reaction system during polymerization to 4.0 or less. By setting the pH of the polymerization reaction system to 4.0 or less, the condensation reaction of the organic silane occurs promptly and the progress of the condensation reaction after the emulsion polymerization can be suppressed, so that the storage stability as a product is improved. The pH of the polymerization reaction system may be more preferably 3.0 or less, and / or more preferably 1.5 or more. The means for adjusting the pH of the polymerization reaction system is not particularly limited. Examples include a mode in which the pre-emulsion solution is adjusted to pH 4.0 or lower, a mode in which the pre-emulsion solution is kept neutral, and a pH is set to 4.0 or lower (for example, about pH 2) by adding other components to the polymerization system. It is done.

High weather resistance (meth) acrylic resins and general purpose (meth) acrylic resins have structural units derived from ethylenically unsaturated monomers. The high weather resistance (meth) acrylic resin has a structural unit derived from a hydrophobic monomer such as cyclohexyl methacrylate, butyl methacrylate, butyl acrylate, etc., and the ratio of the structural unit derived from the hydrophobic monomer is 30% by mass or more. Refers to things. The hydrophobic monomer here refers to a monomer having a solubility in water at 20 ° C. of 1% by mass or less. The polysiloxane-containing aqueous (meth) acrylate-based resin has a structure derived from an ethylenically unsaturated monomer and a structure derived from a hydrolysis condensate of an organosilane compound.

Examples of the general-purpose (meth) acrylate resin include (meth) acrylic acid ester (co) polymers and copolymers containing structural units derived from (meth) acrylic acid esters. Here, (meth) acryl refers to acryl or methacryl, and (co) polymer refers to a polymer or copolymer.
Examples of (meth) acrylic acid ester (co) polymers include poly (meth) methyl acrylate, poly (meth) ethyl acrylate, poly (meth) acrylate propyl, methyl (meth) acrylate / (meth) Examples thereof include butyl acrylate copolymers, ethyl (meth) acrylate / butyl (meth) acrylate copolymers (excluding the above-mentioned high weather resistance (meth) acrylic resins).
Examples of the copolymer containing a structural unit derived from a (meth) acrylate ester include ethylene / methyl (meth) acrylate copolymer and maleic anhydride / methyl (meth) acrylate copolymer ( (Excluding the above-mentioned high weather resistance (meth) acrylic resin).

Among them, it is preferable to use highly durable particles as the polymer particles (A) that coat the outer periphery of the polymer particles (B) when forming a coating film. Specifically, as the polymer particles (A), it is possible to use a highly weather-resistant (meth) acrylate resin, a polysiloxane-containing aqueous (meth) acrylate resin, and a (meth) acrylic composite fluororesin. From the viewpoint of further improving the properties, the water absorption whitening performance of the coating film, and the strength.

In particular, as the polymer particles (A) and (B), a highly weather-resistant (meth) acrylate resin using a hydrophobic monomer and a general-purpose (meth) acrylate-based resin, a polysiloxane-containing aqueous (meth) acrylate-based resin and a general-purpose resin When a combination of a (meth) acrylate resin and a polysiloxane-containing water-based (meth) acrylate resin and a highly weather-resistant (meth) acrylate resin is used, the compatibility between the polymer particles increases and the weather resistance is improved. In addition, the water absorption whitening performance tends to be improved.

Preferably, an embodiment in which the polymer particles (A) have a structure derived from a hydrolytic condensate of an organosilane compound and the polymer particles (B) have a structural unit derived from an ethylenically unsaturated monomer. It is done. More preferably, the polymer particles (A) and the polymer particles (B) are both polymer particles having a structure derived from an ethylenically unsaturated monomer and a structure derived from a hydrolysis condensate of an organosilane compound. An embodiment is mentioned. As still another preferred example, the polymer particles (A) and the polymer particles (B) both have a structure derived from an ethylenically unsaturated monomer and a structure derived from a hydrolysis condensate of an organosilane compound. The ratio of the structural unit derived from the hydrolytic condensate of the organosilane compound to the structural unit derived from the ethylenically unsaturated monomer of the polymer particle (A) is the ratio of the polymer particle (B). The aspect which is the above is mentioned.

In an exemplary embodiment, the emulsion contains the polymer particles (A) in the range of 3 to 20% by mass with respect to the total mass of the polymer particles (A) and the polymer particles (B). When this ratio is 3% by mass or more, the particle interface of the polymer particles (B) is sufficiently covered with the polymer particles (A), and a coating film having excellent weather resistance can be formed. Moreover, it is prevented that a polymer particle (A) and polymeric particle (B) form sea island structure because this ratio is 20 mass% or less, and the weather resistance and intensity | strength of a coating film become favorable. In other words, the emulsion contains the polymer particles (A) in the range of 3 to 20% by mass with respect to the total mass of the polymer particles (A) and the polymer particles (B). ) Around the polymer particles (A) effectively, and the polymer particles (B) maintain a proper sense of distance between them so that the formed coating film has high weather resistance and the like. Conceivable. More preferably, the emulsion contains the polymer particles (A) in a range of 4 to 10% by mass with respect to the total mass of the polymer particles (A) and the polymer particles (B). In other embodiments, the emulsion comprises 3-10% by weight, or 4-20% by weight of polymer particles (A), based on the total weight of polymer particles (A) and polymer particles (B). May be included in the range.

In a typical embodiment, the emulsion has a volume average particle size ratio of the polymer particles (A) and the polymer particles (B) in the range of 1/30 to 5/6. When the particle size ratio is 1/30 or more, the particle size of the polymer particles (A) does not become too small, the amount of surfactant used for production can be reduced, and a coating film excellent in weather resistance can be formed. By being 5/6 or less, the particle interface of the polymer particles (B) is sufficiently covered with the polymer particles (A), and a coating film having excellent weather resistance can be formed. In other words, when the volume average particle size ratio of the polymer particles (A) and the polymer particles (B) is in the range of 1/30 to 5/6, the amount of the surfactant can be reduced, and the polymer Since the polymer particles (A) can sufficiently surround the periphery of the particles (B), it is considered that the formed coating film has high weather resistance and the like. More preferably, the average particle size ratio is in the range of 1/25 to 2/3. In another embodiment, the emulsion has a volume average particle size ratio of the polymer particles (A) and the polymer particles (B) in the range of 1/30 to 2/3, or 1/25 to 5/6. It's okay.

In an exemplary embodiment, the emulsion has a glass transition temperature (Tg) of the polymer particles (A) in the range of 10 to 70 ° C. and a Tg of the polymer particles (B) of −20 to 40 ° C. Range.
When the Tg of the polymer particles (A) is 10 ° C. or higher, the stress at the particle interface is increased, and a coating film having excellent weather resistance can be formed. In other words, when the Tg of the polymer particles (A) is 10 ° C. or more, the particle interface of the coating film formed from the emulsion is strengthened, the hardness of the coating film is increased, and consequently the weather resistance of the coating film is increased. Enhanced. When the Tg of the polymer particles (A) is 70 ° C. or less, the fusion between particles at the particle interface between the particles (A) and (B) easily proceeds during the formation of the coating film, and a tough coating film is formed. Is done. The Tg of the polymer particles (A) is more preferably 20 to 70 ° C.
When the Tg of the polymer particles (B) is −20 ° C. or more, the coating film itself is prevented from being softened, and a coating film having excellent weather resistance can be formed by a synergistic effect with the polymer particles (A). When the Tg of the polymer particles (B) is 40 ° C. or less, the flexibility of the coating film is enhanced, and a coating film having excellent weather resistance can be formed by a synergistic effect with the polymer particles (A). More preferable Tg of the polymer particles (B) may be −20 to 30 ° C., −10 to 40 ° C., or −10 to 30 ° C.

In a typical embodiment, the emulsion has a zeta potential of the polymer particles (A) of 3 mV or more, more preferably 4 mV or more higher than the zeta potential of the polymer particles (B). When the zeta potential difference between the polymer particles (A) and the polymer particles (B) is 3 mV or more, the coating of the polymer particles (A) onto the polymer particles (B) becomes sufficient. When the coating is sufficient, the weather resistance can be improved by a dense film structure. The zeta potential difference is 25 mV or less, and preferably 20 mV or less, from the viewpoint of particle stability. In the emulsion, the zeta potential of the polymer particles (A) is usually 3 mV to 25 mV higher, preferably 3 mV to 20 mV higher, 4 mV to 25 mV higher, or 4 mV than the zeta potential of the polymer particles (B). More than 20 mV.

In one exemplary embodiment, the zeta potential of the polymer particles (B) is greater than −60 mV, preferably greater than −54 mV. When the zeta potential of the polymer particles (B) is larger than −60 mV, the uneven distribution effect of the polymer particles (A) can be obtained, and the polymer particles (B) are appropriately dispersed. The durability of the particle interface between A) and (B) is enhanced. When the zeta potential of the polymer particles (B) is greater than −54 mV, the polymer particles (A) can be more unevenly distributed, and the polymer particles (B) are more appropriately dispersed. The durability of the particle interface between the particles (A) and (B) is further enhanced.

In order to control the zeta potential of polymer particles, a first method is to control the amount of surfactant that is adsorbed and coated on the particle surface. The zeta potential can be increased by increasing the amount of the surfactant to be coated. Examples of the surfactant here include those exemplified as the surfactant used in the emulsion polymerization described below. Secondly, there is a method of controlling the surface area of the polymer particles by adjusting the degree of progress of the polymerization reaction and adjusting the particle diameter. The zeta potential can be increased by reducing the particle diameter, that is, increasing the surface area. Furthermore, the method of controlling by adsorb | sucking the nonionic surfactant which does not have an electric charge on the surface is mentioned. As nonionic surfactant here, what was illustrated as a nonionic surfactant used for the below-mentioned emulsion polymerization can be mentioned. The zeta potential can be increased by adsorbing the nonionic surfactant to the surface. In one embodiment, the zeta potential difference can be adjusted by performing any of these three approaches. As a preferred embodiment, it is preferable to adjust the zeta potential difference by combining a plurality of the above-described methods for the polymer particles (A) and the polymer particles (B) contained in the emulsion.

In one embodiment, the high weather resistance (meth) acrylic resin and the general-purpose (meth) acrylic resin used as polymer particles are obtained by an addition polymerization reaction of an ethylenically unsaturated monomer.
In one embodiment, the polysiloxane-containing aqueous (meth) acrylate resin is obtained by an addition polymerization reaction of an ethylenically unsaturated monomer and a hydrolytic condensation reaction of an organosilane compound. In this case, the ratio of the organosilane compound after condensation with respect to 100 parts by weight of the ethylenically unsaturated monomer is not particularly limited, but from the viewpoint of achieving both fusion between particles and toughness of the coating film, 1 to 60 It is preferable that it is a mass part. From the viewpoint of cost and system stability, the ratio of the organosilane compound is more preferably 3 to 30 parts by mass. In another embodiment, the ratio of the organosilane compound after condensation to 100 parts by weight of the ethylenically unsaturated monomer in this case may be 1 to 30 parts by weight, or 3 to 60 parts by weight.

In one embodiment, the polymerization method of polymer particles includes emulsion polymerization, suspension polymerization, bulk polymerization, and miniemulsion polymerization. As a method for stably producing an emulsion having a volume average particle size of about 10 nm to 1 μm and excellent dispersion stability, it is preferable to use emulsion polymerization.

In one embodiment, the ethylenically unsaturated monomer used in the production of the polymer particles includes (meth) acrylic acid ester (in this application, acrylic acid and methacrylic acid are combined and expressed as (meth) acrylic acid. And unsaturated carboxylic acid ester monomers represented by Examples of unsaturated carboxylic acid ester monomers include (meth) acrylic acid alkyl esters having an alkyl moiety of 1 to 18 carbon atoms. Specific examples include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, (meth) acrylic acid. Examples include 2-ethylhexyl, dodecyl (meth) acrylate, and cycloalkyl ester (meth) acrylate. Among these, cyclohexyl methacrylate, butyl methacrylate, butyl acrylate, and the like are used as a highly weatherable (meth) acrylic resin raw material as a hydrophobic monomer.

Specific examples of other ethylenically unsaturated monomers include (meth) acrylic acid hydroxyalkyl ester (meth) acrylic acid 2-hydroxyethyl, (meth) acrylic acid 2-hydroxypropyl, and the like.

As the ethylenically unsaturated monomer, in addition to the unsaturated carboxylic acid ester monomer, at least one comonomer selected from unsaturated carboxylic acid monomers copolymerizable therewith can be used.

Specific examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, itaconic acid and its monoester, fumaric acid and its monoester, and maleic acid and its monoester. It is particularly preferable to include at least one selected from these groups. These unsaturated carboxylic acid monomers contribute to the mechanical stability of the emulsion particles because the final form of the emulsion is made alkaline with a pH of 7.5 to 9 to form an electric double layer based on carboxyl groups. Tend.

Other ethylenically unsaturated monomers include acrylamide monomers and methacrylamide monomers. Examples thereof include an unsaturated carboxylic acid ester monomer and at least one comonomer copolymerizable with the unsaturated carboxylic acid monomer.

Specific examples of the acrylamide monomer or the methacrylamide monomer include (meth) acrylamide, diacetone (meth) acrylamide, N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide and the like.

Furthermore, other ethylenically unsaturated monomers include aromatic monomers such as vinyltoluene, styrene and α-methylstyrene.

In one embodiment, the organosilane compound used for the production of polymer particles is not particularly limited, but includes an organosilane compound represented by the following formula (1).

(In the formula (1), R ¹ is a phenyl group or a cyclohexyl group, R ² is a hydrogen atom or an aliphatic hydrocarbon group having 1 to 8 carbon atoms, and R ³ is independently an alkoxy group having 1 to 3 carbon atoms. An acetoxy group or a hydroxyl group, and (n, m) is at least one selected from the group consisting of (0,1), (0,2), (1,0) and (2,0).

Preferred examples of the organosilane compound include methyltrimethoxysilane, methyltriethoxysilane, and the like when (n, m) is (0,1). By using these organosilane compounds, it is possible to impart a crosslink density of polysiloxane and to increase the coating film hardness.

In the group where (n, m) is (0, 2), dimethyldimethoxysilane, dimethyldiethoxysilane and the like can be mentioned. By using these organosilane compounds, it is possible to reduce the crosslinking density of the polysiloxane and impart flexibility to the coating film.

In the group where (n, m) is (1, 0), phenyltrimethoxysilane, phenyltriethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane and the like can be mentioned. By using these organosilane compounds, it is possible to impart a crosslink density of polysiloxane and compatibility with a polymer composed of ethylenically unsaturated monomers (A) and (B). .

In the group where (n, m) is (2, 0), diphenyldimethoxysilane, diphenyldiethoxysilane, dicyclohexyldimethoxysilane, dicyclohexyldiethoxysilane and the like can be mentioned. By using these organosilane compounds, the crosslinking density of the polysiloxane can be reduced, and flexibility can be imparted to the coating film.

Examples of other organosilane compounds include organosilane compounds having an ethylenically unsaturated group. Specific examples thereof include γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltriethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-methacryloxypropyltriethoxysilane, and γ-methacryloxypropylmethyldimethoxysilane. Is mentioned. An organosilane compound having an ethylenically unsaturated group is added as a graft point in a polymer formed from an ethylenically unsaturated monomer, and is used to incorporate the organosilane compound as a side chain. In particular, as the organic silane compound constituting the polymer particle (A), a (meth) acrylate-based compound formed by using together an organic silane compound having no ethylenically unsaturated group and an organic silane compound having an ethylenically unsaturated group It is preferable to improve the durability of the particle interface between the particles (A) and the particles (B) using a resin.

In one embodiment, the surfactant used for emulsion polymerization is at least one of an ethylenically unsaturated monomer having a sulfonic acid group or a sulfonate group and an ethylenically unsaturated monomer having a sulfate group. The inclusion is preferable in order to achieve high water resistance of the coating film. The ethylenically unsaturated monomer having a sulfonic acid group or a sulfonate group mentioned here has a radically polymerizable double bond and is a free sulfonic acid group, or an ammonium salt or an alkali metal salt thereof. An anionic surfactant having (ammonium sulfonate group or alkali metal sulfonate group) is preferable.
Examples of such anionic surfactant include Eleminol JS-2, JS-5 (product name, manufactured by Sanyo Chemical Co., Ltd.) Latemu S-120, S-180A, S-180 (product name, Kao Corporation) ) Made).

Further, as an example of a compound having an alkyl ether group having 2 to 4 carbon atoms or a polyalkyl ether group having 2 to 4 carbon atoms, which is an ammonium salt, sodium salt or potassium salt of a sulfonic acid group, for example, Aqualon HS-10 (product) Name, Daiichi Kogyo Seiyaku Co., Ltd.), Adeka Soap SE-1025A, SR-10N, SR-20N (Product Name, ADEKA Co., Ltd.), Aqualon KH-10 (Product Name, Daiichi Kogyo Seiyaku Co., Ltd.) Etc.).

Further, general-purpose nonionic surfactants and nonionic surfactants that are copolymerizable with ethylenically unsaturated monomers, which are called reactive nonionic surfactants, can be used in combination. Examples of such nonionic surfactants include latemul PD-420, latemul PD-430, latemul PD-450 (product name, manufactured by Kao Corporation).

In one embodiment, an ultraviolet absorber and / or a light stabilizer may be contained in the emulsion in order to impart high weather resistance to the coating film. In particular, in order to improve the durability of the particle interface, a commercially available ultraviolet absorber or light stabilizer may be added to the polymer particles (A). In particular, it is preferable to immobilize the polymer particles (A) using a reactive ultraviolet absorber or light stabilizer.

In emulsion polymerization according to an embodiment, addition polymerization of an ethylenically unsaturated monomer can be performed by radical polymerization using heat or a reducing substance as a radical polymerization catalyst. In such emulsion polymerization, water-soluble or oil-soluble persulfates, peroxides, azobis compounds and the like can be advantageously used.

Specific examples of the radical polymerization catalyst include potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, dodecylbenzene sulfonic acid, t-butyl hydroperoxide, t-butyl peroxybenzoate, 2,2-azo. Examples thereof include bisisobutyronitrile, 2,2-azobis (2-diaminopropane) hydrochloride, and 2,2-azobis (2,4-dimethylvaleronitrile).

Among these specific examples of the radical polymerization catalyst, it is preferable to use potassium persulfate, sodium persulfate, or ammonium persulfate that is also effective as a catalyst for promoting the hydrolysis reaction and condensation reaction of the organic silane compound.

The emulsion polymerization method used to provide the emulsion is not particularly limited, and may be a one-stage polymerization method that forms a uniform structure, a multi-stage polymerization method that can form a core-shell structure, or the like. A polymerization method suitable for the purpose can be selected.

Hereinafter, the present invention will be illustrated in detail by examples and comparative examples, but the present invention is not limited to these examples. In addition, the part in an Example and a comparative example represents a mass part, respectively.

<Glass transition temperature of polymer particles>
The glass transition temperature (Tg) of the (meth) acrylate resin is
The constituent mass fractions of the constituent monomers a, b... In the polymer are Wa, Wb..., And the glass transition temperature of the homopolymer of the constituent monomers a, b. , Tgb..., The Tg value of the polymer was determined by the FOX equation shown below.
1 / Tg = Wa / Tga + Wb / Tgb + ...
The glass transition temperatures (Tg) calculated for the (meth) acrylate resins used are listed in Table 1-2.

Moreover, about the physical property test and coating-film performance evaluation of the obtained emulsion, it implemented according to the evaluation and test method which are shown below.
<Measurement of volume average particle diameter>
The volume average particle diameter of the obtained emulsion was measured with a Microtrac particle size distribution meter manufactured by Leeds & Northrup.

<Measurement of zeta potential>
The zeta potential of the obtained emulsion was measured by diluting with a 10 mM aqueous KCl solution.
The measurement conditions for the zeta potential are as follows.
・ Device name: ELSZ-1000 manufactured by Otsuka Electronics Co., Ltd.
・ Measurement temperature: 25 ℃
The calculation of the zeta potential from the electrophoretic mobility was performed by a method using the Smoluchowski equation.

<Preparation of clear paint>
In order to confirm the effect of blending on the coating film performance, a clear coating was prepared for each of the polymer particle (B) single emulsion and the emulsion obtained by blending the polymer particles (A) with the polymer particles (B). The clear paint was prepared by blending 10% ethylene glycol monobutyl ether (diluted to 50% with water at the time of use) and 20% texanol as a film-forming aid with respect to the total solid content in the emulsion. A blending example is shown below.
Emulsion: 100 parts (in case of solid content of 40% by mass)
-Ethylene glycol monobutyl ether / water = 1/1: 8 parts-Texanol: 8 parts

<Water absorption whitening evaluation>
Apply clear paint to a glass plate with a 0.1 mm applicator, dry at 23 ° C overnight, then immerse in 23 ° C water for 24 hours, change rate of haze value before immersion Were manufactured by Nippon Denshoku Industries Co., Ltd .: Comparative measurement was performed with a haze meter NDH5000.
The haze after the above-described treatment for the coating film of the emulsion in which the polymer particles (A) are blended with respect to the change rate of the haze value after the above-mentioned treatment for the coating film of the emulsion consisting solely of the polymer particles (B). The rate of change of values was compared. The water absorption whitening of the coating film of the emulsion blended with the polymer particles (A) was evaluated according to the following criteria by increasing or decreasing the change rate of the haze value of both.
A (sufficient improvement): The change rate of haze value decreased by 2% or more, and water absorption whitening was improved.
○ (Improved): The rate of change in haze value decreased by less than 0.3-2%, and water absorption whitening was improved.
-(No improvement): The change in the change rate of the haze value was less than ± 0.3%.
Δ (slightly worsening): The rate of change in haze value increased by less than 0.3 to 2%, and water absorption whitening worsened.
X (Deterioration): The rate of change in haze value increased by 2% or more, and water absorption whitening deteriorated.

<Weather resistance evaluation>
The self-made black enamel paint is applied on an aluminum plate and dried at 100 ° C. for 10 minutes. The resulting clear paint is then applied with a 0.25 mm applicator and dried at 100 ° C. for 10 minutes. A sample for an accelerated weather resistance test was prepared. The sample was processed by a die plastic company: metal weather tester under the following acceleration conditions, and the initial gloss value and the gloss value at every predetermined time were measured.
Irradiation: 81 mW / cm ² 63 ° C., 50 RH%, 4 hr
・ Shower: 30 sec
Dark / wet: 30 ° C, 98RH%, 4hr
・ Drying: 40 ° C, 20RH%, 20min
Gloss value measurement: measured every 15 cycles (125 hr) Polymer particles for the cycle time at which the gloss value reached 80% of the initial gloss value for the coating film of the polymer particle (B) alone as the main polymer particle The cycle time when the gloss value reached 80% of the initial gloss value for the coating film of the emulsion blended with (A) was compared. The weather resistance of the coating film of the emulsion blended with the polymer particles (A) was evaluated according to the following criteria based on the length of the 80% arrival time.
A (sufficiently improved): 80% arrival time was extended by 250 hours or more.
○ (improved): 80% arrival time was extended by 125 hours.
-(No improvement): 80% arrival time was not changed.
X (deteriorated): 80% of the arrival time was shortened.

[Production Example of Polymer Particle (A) (A) -1]
In a 2.2-liter SUS separable flask equipped with a stirrer, reflux condenser, dropping tank and thermometer, 931.1 parts of water and Neoperex G15 as a surfactant (product name, Kao Corporation) 55.0 minutes after the temperature was raised to 80 ° C., 6.0 parts of a 2% aqueous solution of ammonium persulfate was added. Next, 8.0 parts of methyl methacrylate, 100.0 parts of cyclohexyl methacrylate, 192.0 parts of butyl methacrylate, 74.8 parts of butyl acrylate, 20.0 parts of 2-hydroxyethyl methacrylate, 4. 0 part, 0.8 part of acrylic acid, 0.4 part of acrylamide, 16.0 parts of 25% aqueous solution of Aqualon KH-10 (product name, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), 10% of sodium styrenesulfonate Prepare a mixed solution of 0.4 part aqueous solution, 8.0 parts Emulgen 120 (product name, manufactured by Kao Corporation, 20% aqueous solution), 18.0 parts 2% aqueous solution of ammonium persulfate, and 443.6 parts water. The mixture was emulsified with a homomixer for 5 minutes to obtain a pre-emulsion.
Next, as an organic silane compound component, methyltrimethoxysilane Z6366 (product name, manufactured by Toray Dow Corning Co., Ltd.) 13.5 parts, dimethyldimethoxysilane Z6329 (product name, manufactured by Toray Dow Corning Co., Ltd.) 21.6 2 parts of γ-methacryloxypropyltrimethoxysilane SZ6030 (product name, manufactured by Toray Dow Corning Co., Ltd.) and the resulting pre-emulsified liquid were added to a Y-shaped tube (100 mesh at the outlet of the Y-shaped tube). Filled with a wire mesh and filled with molecular sieves 3A (product name: Wako Pure Chemical Industries, Ltd.) until the two dripping tanks are mixed together, so that the organosilane compound component and the pre-emulsified liquid can be mixed gently. Adjusted. ] Was allowed to flow from the dropping tank into the reaction vessel over 2 hours. During the inflow, the temperature in the reaction vessel was kept at 80 ° C. After the inflow was completed, the temperature in the reaction vessel was kept at 80 ° C. for 30 minutes.
Then, it cooled to room temperature, filtered the emulsion with 100 mesh, and when hydrogen ion concentration was measured, it was pH 2.8. Next, 25% aqueous ammonia was added to adjust the pH to 8.3.
The obtained emulsion had a solid content of 22.7%, a volume average particle size of 27 nm, and a zeta potential of -44 mV. The respective raw materials and the blending ratio (parts by mass) are shown in Table 1-1. The results of these physical properties are shown in Table 1-2.

[Production Examples of Polymer Particles (A) (A) -2 to (A) -7]
The emulsion was subjected to the same treatment as in Production Example (A) -1, except that the raw materials and blending ratio (parts by mass) of ethylenically unsaturated monomers and organosilane compounds listed in Table 1-1 were used. Manufactured. The solid content, pH after adjustment, volume average particle diameter, zeta potential and the like of the obtained emulsion are shown in Table 1-2.

[Production Example of Polymer Particle (B) (B) -1]
6. In a 2.2-liter SUS separable flask equipped with a stirrer, reflux condenser, dropping tank and thermometer, 430.0 parts of water and 25% aqueous solution of Aqualon KH-10 as a surfactant were added. Two parts were added, and 5 minutes after raising the temperature to 80 ° C., 15.0 parts of a 2% aqueous solution of ammonium persulfate was added. Subsequently, for the raw materials such as the ethylenically unsaturated monomer and the organosilane compound, the parts by mass shown in Table 2-1 were weighed to prepare a mixed solution, and the mixed solution was emulsified with a homomixer for 5 minutes. 1-stage and 2-stage pre-emulsified liquids were obtained. Next, the pre-emulsified liquid in the first stage in the table was flown in 100 minutes, and after curing for 30 minutes, the pre-emulsified liquid in the second stage in the table was flown in in 100 minutes, and a curing treatment was performed for 90 minutes. The solid content, pH after adjustment, volume average particle diameter, zeta potential, and the like of the obtained emulsion are shown in Table 2-2.

[Production Examples of Polymer Particles (B) (B) -2 to 5, (B) -7]
The emulsion was subjected to the same treatment as in Production Example (B) -1, except that the ethylenically unsaturated monomers and organic silane compounds shown in Table 2-1 were changed to raw materials and blending ratios (parts by mass). Manufactured. The solid content, pH after adjustment, volume average particle diameter, zeta potential, and the like of the obtained emulsion are shown in Table 2-2.

Each abbreviation in the table is as follows.
MMA: methyl methacrylate: glass transition temperature 105 ° C.
CHMA: cyclohexyl methacrylate: glass transition temperature 83 ° C
BMA: butyl methacrylate: glass transition temperature 22 ° C
-BA: Butyl acrylate: Glass transition temperature -45 ° C
EHA: 2-ethylhexyl acrylate: glass transition temperature -55 ° C
2HEMA: 2-hydroxyethyl methacrylate: glass transition temperature 55 ° C
MAA: methacrylic acid: glass transition temperature 144 ° C
AA: Acrylic acid: Glass transition temperature 87 ° C
AAm: Acrylamide: Glass transition temperature 153 ° C
・ KH10: (Product name) Aqualon KH10: Polymerization concentration 25%
Nass: styrene sulfonic acid Na: polymerization concentration 10%
G15: (Product name) Neoperex G15: Polymerization concentration 16%
D3D: (Product name) Emar D3D: Polymerization concentration 26%
Em120: (Product name) Emulgen 120: Polymerization concentration 20%
APS: ammonium peroxosulfate: polymerization concentration 2%
-Z6366: (Product name) Methyltrimethoxysilane-Z6329: (Product name) Dimethyldimethoxysilane-KBM103: (Product name) Phenyltrimethoxysilane-KBM202SS: (Product name) Diphenyldimethoxysilane-SZ6030: (Product name) γ -Methacryloxypropyltrimethoxysilane

<Confirmation of Tg factor>
[Example 1]
8.8 parts of polymer particles (A) -1 emulsion (solid content 22.7%) and 86.4 parts of polymer particles (B) -1 emulsion (solid content 44.0%) were blended, Next, 4.8 parts of water was added so that the total solid content was 40%, and stirring was performed. While stirring this emulsion, 8 parts of ethylene glycol monobutyl ether diluted with 50% of water and 8 parts of texanol were added dropwise as a film-forming aid to prepare a clear paint.
Next, for comparison, 90.9 parts of polymer particle (B) -1 alone emulsion (solid content 44.0%) is weighed, and 9.1 parts of water is added so that the solid content is 40%. Stirring was performed. Similarly, 8 parts of ethylene glycol monobutyl ether diluted to 50% with water and 8 parts of texanol were added dropwise as a film-forming aid while stirring this emulsion to prepare a clear paint (Reference Example 1).

The haze value change rate after the water absorption whitening test of the coating obtained from the clear coating of polymer particle (B) -1 alone was measured and found to be 85.3%. Next, the haze value change rate after the water absorption whitening test of the coating obtained from the clear coating containing the polymer particles (A) -1 and the polymer particles (B) -1 decreased to 63.2%.
The time required to reach a gloss retention of 80% in a weathering accelerated test of the coating obtained from the clear coating of polymer particle (B) -1 alone was 500 hr. Next, the gloss retention time of 80% achieved by the accelerated weathering test of the coating obtained from the clear coating material containing the polymer particles (A) -1 and the polymer particles (B) -1 was improved to 750 hr.
Table 3 shows the blended solid content ratio of the polymer particles (A) and (B), the calculated Tg value, the volume average particle diameter, and the zeta potential. Further, the haze value change rate in the water absorption whitening test and the weather resistance acceleration test The gloss retention time of 80% was described, and the evaluation of the improvement effect compared with Reference Example 1 was described.

[Example 2]
As in Example 1, the emulsions of polymer particles (A) -4 and polymer particles (B) -1 were blended at the blending solid content ratio shown in Table 3 so that the total solid content was 40%. Adjusted. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1. In Table 3, the calculated Tg values, volume average particle diameters, and zeta potentials of the polymer particles (A) and (B) of this example are described, and further, the haze value change rate in the water absorption whitening test and the weather resistance acceleration test. The gloss retention time of 80% was described, and the evaluation of the improvement effect compared with Reference Example 1 was described.

[Comparative Example 1]
Each emulsion of polymer particles (A) -5 and polymer particles (B) -1 was blended at a blended solid content ratio shown in Table 3, and adjusted so that the total solid content was 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1.
As shown in Table 3, the effect of improving the gloss retention of 80% in the accelerated weathering test can be confirmed as compared with the clear coating of the polymer particle (B) -1 alone (Reference Example 1). There wasn't. It was assumed that the Tg of the polymer particles (A) -1 was low and the water resistance was not improved.

[Comparative Example 2]
Each emulsion of polymer particles (A) -6 and polymer particles (B) -1 was blended at a blended solid content ratio shown in Table 3 and adjusted so as to have a total solid content of 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1.
As shown in Table 3, the effect of improving the gloss retention of 80% in the accelerated weathering test can be confirmed as compared with the clear coating of the polymer particle (B) -1 alone (Reference Example 1). There wasn't. The polymer particles (A) -1 had a high Tg, and it was presumed that the weather resistance was not improved due to a decrease in the elongation of the film.

[Comparative Example 3]
Except that the emulsions of the polymer particles (A) -1 and polymer particles (B) -2 were blended at the blending solid content ratios shown in Table 3 and adjusted so that the total solid content was 40%. A clear paint was obtained in the same manner as in Example 1, and each physical property was evaluated.
As shown in Table 3, the effect of improving the gloss retention time of 80% in the accelerated weathering test can be confirmed as compared with the clear coating of the polymer particle (B) -2 alone (Reference Example 2). There wasn't. It was presumed that the polymer particles (B) -2 had a low Tg, and the weather resistance was not improved due to a decrease in water resistance.

[Comparative Example 4]
Each emulsion of polymer particles (A) -1 and polymer particles (B) -3 was blended at a blended solid content ratio shown in Table 3 and adjusted so that the total solid content was 40%. Using this, a clear paint was obtained in the same manner as in Example 1, and each physical property was evaluated.
As shown in Table 3, the haze value change rate in the water absorption whitening test was lower than that of the clear coating film of the polymer particles (B) -3 alone (Reference Example 3). Further, the gloss retention time of 80% in the accelerated weathering test was not improved. When the Tg of the polymer particles (B) -3 was high, it was presumed that the blending effect was not achieved and the improvement was not achieved.

<Confirmation of quantitative ratio factor>
[Examples 3 to 4]
In the same manner as in Example 1, the emulsions of the polymer particles (A) and the polymer particles (B) were blended at the blending solid content ratio shown in Table 4 and adjusted so that the total solid content was 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1.
Table 4 shows the calculated Tg values, volume average particle diameters, and zeta potentials of the polymer particles (A) and (B) of each Example, and further, the haze value change rate in the water absorption whitening test, and the weather resistance acceleration test. The gloss retention time of 80% was described, and the evaluation of the improvement effect compared with Reference Example 1 was described.

In addition, the following operation was performed about Example 4 and the emulsion particle | grains were isolate | separated.
<Operation method>
25 g of an emulsion containing polymer particles (A-1) and polymer particles (B-1) was collected in a centrifuge tube, added with an aqueous sodium chloride solution (0.1 M, 0.8 g), and then manufactured by Beckman Coulter, Inc .: OPTIMA Centrifugation was performed at 20,000 rpm, 15 ° C. for 1 hour in L-90. After collecting the supernatant, distilled water and sodium chloride aqueous solution (0.1 M, 0.8 g) of the collected weight were added, and the same operation was repeated 5 times in total. When the amount collected was calculated from the solid content concentration of the collected supernatant, it was 1.1 g, and the volume average particle diameter was 40 nm. The volume average particle size of the precipitate was 139 nm.

[Comparative Example 5]
Each emulsion of polymer particles (A) -1 and polymer particles (B) -1 was blended at a blended solid content ratio shown in Table 4 and adjusted so that the total solid content was 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1.
As shown in Table 4, the effect of improving the gloss retention time of 80% in the accelerated weathering test can be confirmed as compared with the clear coating of the polymer particle (B) -1 alone (Reference Example 1). There wasn't. It was presumed that the amount ratio of the polymer particles (A) -1 was low, the blending effect was not exhibited, and the weather resistance was not improved.

[Comparative Example 6]
Each emulsion of polymer particles (A) -1 and polymer particles (B) -1 was blended at the blending solid content ratio shown in Table 4 to obtain an emulsion having a total solid content of 37%. While stirring this emulsion, 7.3 parts of ethylene glycol monobutyl ether diluted to 50% with water and 7.3 parts of texanol were added dropwise as a film-forming aid to produce a clear paint. Each physical property was evaluated.
Next, for comparison, 84.1 parts of polymer particle (B) -1 single emulsion (solid content 44.0%) is weighed, and 15.9 parts of water is added so that the solid content is 37%. Stirring was performed. Similarly, while stirring this emulsion, 7.3 parts of ethylene glycol monobutyl ether diluted to 50% with water and 7.3 parts of texanol were added dropwise as a film forming aid to produce a clear paint. Each physical property was evaluated in the same manner as described above (Reference Example 1 ′).
As described in Table 4, the time to reach a gloss retention of 80% according to the accelerated weathering test was determined for the polymer film (B) -1 alone clear coating (Reference Example 1 ′) adjusted to a solid content of 37%. Compared to performance. It was presumed that the amount ratio of the polymer particles (A) -1 was high, the blending effect was not exhibited, and the weather resistance was not improved.

<Confirmation of volume average particle ratio factor>
[Examples 5 to 7]
In the same manner as in Example 1, the emulsions of the polymer particles (A) and the polymer particles (B) were blended at the blending solid content ratio shown in Table 5 and adjusted so that the total solid content was 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1. Table 5 shows the calculated Tg values, volume average particle diameters, and zeta potentials of the polymer particles (A) and (B) of each example, and further, the haze value change rate in the water absorption whitening test, and the weather resistance acceleration test. The gloss retention 80% arrival time was described, and the evaluation of the improvement effect was described.

[Comparative Example 7]
Each emulsion of polymer particles (A) -2 and polymer particles (B) -5 was blended at the blending solid content ratio shown in Table 5 and adjusted so that the total solid content was 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1.
As shown in Table 5, the effect of improving the retention time of 80% gloss retention by the accelerated weathering test can be confirmed as compared with the clear coating of the polymer particle (B) -5 alone (Reference Example 5). There wasn't. Since the volume average particle size ratio of the polymer particles (A) to the polymer particles (B) is low (the difference between the volume average particle sizes is large), the blending effect is not expressed and the weather resistance is not improved. I guessed.

[Comparative Example 8]
Each emulsion of polymer particles (A) -3 and polymer particles (B) -4 was blended at a blended solid content ratio shown in Table 5 and adjusted so that the total solid content was 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1.
As shown in Table 5, the effect of improving the gloss retention time of 80% according to the accelerated weathering test can be confirmed as compared with the clear coating of the polymer particles (B) -4 alone (Reference Example 4). There wasn't. Since the volume average particle diameter ratio of the polymer particles (A) to the polymer particles (B) is high (the difference between the volume average particle diameters is small), the blending effect is not expressed and the weather resistance is not improved. I guessed.

<Confirmation of zeta potential difference>
[Examples 1, 5, and 7]
In the same manner as in Example 1, the emulsions of polymer particles (A) and polymer particles (B) were blended at the blending solid content ratio shown in Table 6 and adjusted so as to have a total solid content of 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1. In Table 6, the calculated Tg values, volume average particle diameters, and zeta potentials of the polymer particles (A) and (B) of each Example are described, and further, the haze value change rate in the water absorption whitening test and the weather resistance acceleration test. The gloss retention 80% arrival time was described, and the evaluation of the improvement effect was described.

[Comparative Example 9]
Each emulsion of polymer particles (A) -7 and polymer particles (B) -1 was blended at a blended solid content ratio shown in Table 6 and adjusted so that the total solid content was 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1.
As shown in Table 6, the effect of improving the retention time of gloss retention of 80% in the accelerated weathering test can be confirmed as compared with the clear coating of the polymer particles (B) -1 alone (Reference Example 1). There wasn't. If the zeta potential difference was small, the blending effect was not expressed, and it was assumed that the weather resistance was not improved.

<Confirmation of zeta potential of polymer (B)>
[Examples 1 and 6]
In the same manner as in Example 1, the emulsions of the polymer particles (A) and the polymer particles (B) were blended at the blending solid content ratio shown in Table 7 and adjusted so as to have a total solid content of 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1. Table 7 shows the calculated Tg values, volume average particle diameters, and zeta potentials of the polymer particles (A) and (B) of each example, and further, the haze value change rate in the water absorption whitening test, and the weather resistance acceleration test. The gloss retention 80% arrival time was described, and the evaluation of the improvement effect was described.

[Comparative Example 10]
As in Example 1, the emulsions of polymer particles (A) -3 and polymer particles (B) -5 were blended at the blending solid content ratio shown in Table 7 so that the total solid content was 40%. Adjusted. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1. Table 7 shows the calculated Tg values, volume average particle diameters, and zeta potentials of the polymer particles (A) and (B) of each example, and further, the haze value change rate in the water absorption whitening test, and the weather resistance acceleration test. The gloss retention 80% arrival time was described, and the evaluation of the improvement effect was described.
As shown in Table 7, the haze value change rate in the water absorption whitening test was slightly improved compared to the clear coating film of the polymer particle (B) -5 alone (Reference Example 5). It was not big. In addition, the gloss retention 80% time achieved by the accelerated weathering test was improved compared to the clear coating film of the polymer particle (B) -5 alone (Reference Example 5). It was half of the improvement in Example 1 (the zeta potential of the polymer (B) was -53 mV). In Comparative Example 10, when the zeta potential of the polymer (B) was 3 mV below −54 mV, it was presumed that although the blending effect was exhibited to some extent, the effect was not great.

[Comparative Example 11]
Each emulsion of polymer particles (A) -3 and polymer particles (B) -7 was blended at a blended solid content ratio shown in Table 7 and adjusted so that the total solid content was 40%. Using this, a clear paint was obtained, and each physical property was evaluated in the same manner as in Example 1.
As shown in Table 7, the effect of improving the retention time of gloss retention of 80% in the accelerated weathering test can be confirmed as compared with the clear coating of the polymer particles (B) -7 alone (Reference Example 6). There wasn't. When the zeta potential of the polymer (B) was 6 mV below -54 mV, it was presumed that the blending effect was not expressed and the weather resistance was not improved.

<Evaluation of coating cross-sectional form>
The clear paint blended in Example 2 was applied on a polypropylene plate with a 0.25 mm applicator, dried at 100 ° C. for 10 minutes, then embedded in an epoxy resin, and an ultramicrotome was used. A thin film slice was prepared, and a dark field image in a cross-sectional form was shown in FIG. For the dark field image, the black part indicates a (meth) acrylate resin obtained by addition polymerization reaction of an ethylenically unsaturated monomer, and the white part indicates a resin containing an organic silane compound which is a heavier element. ing. It was confirmed from the image that a thin coating of a white portion was formed on the outer periphery of the black particles and a particle interface was formed.
On the other hand, in the dark field image of the coating film composed of the emulsion of the polymer particles (B) alone, no white portion on the outer peripheral portion was observed.

The emulsion of the present invention is useful as a coating material, a base treatment material or finishing material for building materials, an adhesive, a paper processing agent, or a finishing material for woven or non-woven fabrics. In addition, this emulsion is particularly used as a paint or a building finishing material for various foundations such as inorganic building materials such as concrete, cement mortar, extruded plate, foamable concrete, building materials based on woven or non-woven fabrics, and metal building materials. Furthermore, it is useful as a main material for a multi-layer finish coating material and a synthetic resin emulsion paint such as a top coat.

Claims

Water, polymer particles (A) having a glass transition temperature of 10 ° C. to 70 ° C., and polymer particles (B) having a glass transition temperature of −20 ° C. to 40 ° C., the polymer particles (A) being The polymer particles (A) and the polymer particles (B) are contained in the range of 3% by mass to 20% by mass with respect to the total mass of the polymer particles (A) and the polymer particles (B). The zeta potential of the polymer particles (A) is 3 mV or more and 25 mV or less higher than the zeta potential of the polymer particles (B). And the zeta potential of the polymer particles (B) is greater than -54 mV.
The emulsion according to claim 1, wherein the polymer particles (A) and / or the polymer particles (B) have a structural unit derived from an ethylenically unsaturated monomer.
The emulsion according to claim 1 or 2, wherein the polymer particles (A) and / or the polymer particles (B) have a structural unit derived from a hydrolytic condensate of an organosilane compound.
The polymer particle (A) has a structural unit derived from a hydrolysis condensate of an organosilane compound, and the polymer particle (B) has a structural unit derived from an ethylenically unsaturated monomer. 3. The emulsion according to 3.
The polymer particles (A) and the polymer particles (B) both have a structural unit derived from an ethylenically unsaturated monomer and a structural unit derived from a hydrolysis condensate of an organosilane compound. The emulsion as described.
The ratio of the structural unit derived from the hydrolysis condensate of the organosilane compound to the structural unit derived from the ethylenically unsaturated monomer of the polymer particle (A) is equal to or higher than the ratio of the polymer particle (B). 5. The emulsion according to 5.
An emulsion comprising water, polymer particles (A), and polymer particles (B) having a volume average particle size larger than that of the polymer particles (A), wherein ethylene is added to the total solid content of the emulsion. In a STEM dark field image of a coating film formed from a clear paint blended with 10% by mass of glycol monobutyl ether and 20% by mass of texanol, the polymer particles (A) cover the polymer particles (B). Emulsion.