JP7585286B2 - New emulsion and coating composition using said emulsion - Google Patents

Description

The present invention relates to novel emulsions, etc.

In terms of environmental considerations, paints for the interior and exterior of buildings (topcoats and topcoats) are gradually shifting from solvent-based paints to water-based paints.

As an example of such a water-based paint, Patent Document 1 discloses a resin emulsion for topcoat paint made of an acrylic resin that uses a styrene monomer and a silane group-containing monomer as raw materials.

JP 2017-179313 A

The object of the present invention is to provide a novel emulsion and a composition (particularly a coating composition) containing this emulsion.

Another object of the present invention is to provide an emulsion that can efficiently form a coating film with excellent water resistance, and a composition containing this emulsion.

Another object of the present invention is to provide an emulsion with excellent thickening response and a composition containing this emulsion.

As in Patent Document 1, water-based paints that use emulsions are known, but the inventors' research has revealed that some of these water-based paints do not have sufficient water resistance, and in some cases, problems such as peeling of the coating film due to a decrease in coating film strength can occur when the coating is exposed to rain during painting or when the coating is applied in humid conditions such as during the rainy season.

The viscosity of the paint can be adjusted by adding a thickener, but the inventors' investigations have revealed that, depending on the type of emulsion (or the polymer that constitutes the emulsion), the thickener may not be able to impart sufficient viscosity (i.e., the thickening response may be insufficient), requiring a large amount of thickener, and that using such a large amount of thickener may have adverse effects on the formation of the coating film (for example, reducing the water resistance of the coating film or increasing the viscosity over time during storage).

In this situation, the present inventors have conducted further intensive research to solve the above problems, and as a result have discovered that by forming the polymerization components of the emulsion (or the polymer that constitutes the emulsion) from polymerization components that contain at least a reactive emulsifier (A) having multiple aromatic groups and a silane coupling agent (B) having a polymerizable unsaturated bond group, it is possible to form a coating film with excellent water resistance and improve or enhance the thickening response.

The inventors have made various other discoveries in addition to those mentioned above, and have further pursued intensive research to complete the present invention.

That is, the present invention relates to the following inventions, etc.
[1]
An emulsion of a (meth)acrylic polymer, comprising as polymerization components at least a reactive emulsifier (A) having a plurality of aromatic groups and a silane coupling agent (B) having a polymerizable unsaturated bond group.
[2]
The emulsion according to [1], wherein the reactive emulsifier (A) contains a reactive emulsifier represented by the following formula (1):
(In the formula, D represents the following formula (D-1) or (D-2), A represents an alkylene group having 2 to 4 carbon atoms, T represents a hydrogen atom or _-SO3M (M represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom or _NH4 ), l represents 1 to 2, m represents 1 to 3, and n represents 1 to 1000.)
(In the formula, R ¹ represents a hydrogen atom or a methyl group.)
[3]
The emulsion according to [1] or [2], wherein the polymerization components further contain one or more monomers selected from a monomer having an alicyclic group and a monomer having an aromatic group.
[4]
The emulsion according to any one of [1] to [3], wherein the proportion of the reactive emulsifier (A) is 0.1 to 10 mass% based on the total polymerization components.
[5]
The emulsion according to any one of [1] to [4], wherein the ratio of the silane coupling agent (B) is 0.05 to 10 mass% based on the total amount of the polymerization components.
[6]
The emulsion according to any one of [1] to [5], wherein the proportion of emulsifiers other than the reactive emulsifier (A) is 5 mass% or less based on the total polymerization components.
[7]
The emulsion according to any one of [1] to [6], wherein the (meth)acrylic polymer has a glass transition temperature of −40 to 80° C.
[8]
The coating composition comprises a reactive emulsifier (A) having a plurality of aromatic groups, an emulsion of a (meth)acrylic polymer having at least 2-ethylhexyl (meth)acrylate as a polymerization component, and a urethane association type thickener.
[9]
The composition according to [8], wherein the emulsion is an emulsion according to any one of [1] to [7].
[10]
A paint comprising the emulsion according to any one of [1] to [7] or the composition according to any one of [8] to [9].
[11]
A coating film formed from the coating material according to [10].
[12]
A building having the coating film according to [11].
[13]
A building material having the coating film according to [11].

The present invention provides a novel emulsion and a composition containing the emulsion. Such an emulsion and composition are useful for coatings, etc.

In another aspect of the present invention, an emulsion and composition can be provided that can efficiently form a coating film with excellent water resistance.

In another aspect of the present invention, an emulsion having excellent thickening response (capable of improving or enhancing thickening response) and a composition containing this emulsion can be provided.
In such an emulsion, sufficient viscosity can be obtained even if the amount of thickener is reduced. Therefore, even with a small amount of thickener, a coating film can be efficiently formed, and in particular, a coating film having excellent water resistance as described above can be formed. In addition, since it is not necessary to use a large amount of thickener, the adverse effects of using a thickener in coating film formation (for example, viscosity increase over time during storage) can be reduced.

<Emulsion>
The emulsion of the present invention is an emulsion of a (meth)acrylic polymer (hereinafter, sometimes referred to as a (meth)acrylic polymer (a)) having at least a reactive emulsifier (A) having a plurality of aromatic groups and a silane coupling agent (B) having a polymerizable unsaturated bond group as at least polymerization components (or monomer components).
In the present invention, the polymerization component of the (meth)acrylic polymer (a) contains the reactive emulsifier (A) (particularly in combination with the silane coupling agent (B)), so that the water resistance of the coating film can be efficiently improved or enhanced.
In addition, by using such a specific reactive emulsifier (A), an emulsion having excellent thickening response can be efficiently obtained. In particular, such thickening response can be further improved or enhanced by combining with a silane coupling agent (B).

The emulsion of the present invention is generally a dispersion of a (meth)acrylic polymer (or polymer particles) in an emulsion state in a solvent.

(Reactive emulsifier (A))
The reactive emulsifier (or reactive surfactant) (A) usually has a reactive group (or a polymerizable group).
As the reactive group, a polymerizable unsaturated bond group (particularly, a carbon-carbon double bond) is preferred.

In the reactive emulsifier (A), the aromatic group is not particularly limited, and examples thereof include C _6-20 aromatic hydrocarbon groups such as phenyl group and naphthyl group.
The number of aromatic groups may be 2 or more, for example, 2 to 10, 2 to 8, 2 to 6, or 2 to 4.

The reactive emulsifier (A) may be, for example, an anionic emulsifier, a nonionic emulsifier, a cationic emulsifier, an amphoteric emulsifier, etc., and from the viewpoint of the dispersibility of the emulsion particles, an anionic emulsifier is preferred.

Examples of anionic emulsifiers include sulfonate compounds and sulfate compounds.

As the reactive emulsifier (A), for example, a reactive emulsifier represented by the following formula (1) is preferable.
(In the formula, D represents the following formula (D-1) or (D-2), A represents an alkylene group having 2 to 4 carbon atoms, T represents a hydrogen atom or _-SO3M (M represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom or _NH4 ), l represents 1 to 2, m represents 1 to 3, and n represents 1 to 1000.)

(In the formula, R ¹ represents a hydrogen atom or a methyl group.)

In particular, reactive emulsifiers represented by the following formula (2) are preferred.

(In the formula, M represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom, or _NH4 , m represents 1 to 3, and n represents 1 to 1000.)

In M in the above formulae (1) and (2), the alkali metal atom is preferably, for example, sodium or potassium.
As the alkaline earth metal atom, for example, magnesium, calcium, etc. are preferable.

Commercially available products may be used as the reactive emulsifier (A), such as those manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd. under the trade names AQUALON AR-10, AQUALON AR-1025, AQUALON AR-20, and AQUALON AR-2020.

The reactive emulsifier (A) may be used alone or in combination of two or more.

In the polymerization components, the proportion of the reactive emulsifier (A) varies depending on the types of other monomers, but from the viewpoint of improving the water resistance of the coating film, it may be, for example, 0.1 mass % or more of the total polymerization components (or the total monomer components), preferably 0.5 mass % or more, more preferably 1 mass % or more, and particularly preferably 1.3 mass % or more (for example, 1.5 mass % or more, 2 mass % or more, etc.).
In the polymerization components, the proportion of the reactive emulsifier (A) may be, for example, 20 mass % or less, preferably 15 mass % or less, and more preferably 10 mass % or less, of the total polymerization components.

These upper and lower limits may be appropriately combined to set an appropriate range (e.g., 1-10% by mass, 1.5-10% by mass, etc.) (the same goes for others).

In the polymerization components, the proportion of the reactive emulsifier (A) will vary depending on the types of other monomers, but from the viewpoint of improving the water resistance of the coating film, it may be, for example, 0.01 mol % or more of the total polymerization components, preferably 0.05 mol % or more, more preferably 0.1 mol % or more, and particularly preferably 0.13 mol % or more (e.g., 0.15 mol % or more, 0.2 mol % or more, etc.).
In the polymerization components, the proportion of the reactive emulsifier (A) may be, for example, 20 mol % or less, preferably 15 mol % or less, and more preferably 10 mol % or less, of the total polymerization components.

These upper and lower limits may be appropriately combined to set an appropriate range (e.g., 0.1 to 10 mol%, 0.15 to 10 mol%, etc.) (same for others).

(Silane Coupling Agent (B))
The silane coupling agent (B) usually has a polymerizable unsaturated bond group.
Examples of the polymerizable unsaturated bond group include a vinyl group, an allyl group, and a (meth)acryloyl group.
The number of polymerizable unsaturated bond groups is not particularly limited and may be 1 or more.

The silane coupling agent (B) may, for example, be one having a silyl group to which a hydrolyzable (condensable) group (such as an alkoxy group or a halogen atom) is bonded.
In the silane coupling agent (B), the number of silicon (atoms) may be 1 or more, and may be 2 or more (for example, an oligomer or polymer type silane coupling agent).

The silane coupling agent (B) may be, for example, a silane coupling agent (compound) represented by the following formula (3).
(R2) _n1 -Si-(R3) _4-n1 (3)
(In the formula, R2 is the same or different and represents a group having a polymerizable unsaturated bond group. R3 is the same or different and represents a hydrogen atom, a hydrolytic condensable group, a hydrocarbon group, or an epoxy group (an epoxy group-containing group). n1 is an integer of 1 to 3.)

In R2, examples of the polymerizable unsaturated bond group include a vinyl group, an allyl group, and a (meth)acryloyl group.

In R3, examples of the hydrocarbon group include an alkyl group, an aryl group (such as a phenyl group), etc. Examples of the alkyl group include a _C1-4 alkyl group such as a methyl group, an ethyl group, etc.

In R3, examples of the hydrolytic condensable group include a hydroxyl group, a halogen atom (such as a chlorine atom), an alkoxy group, an acyloxy group, an aryloxy group (such as a phenoxy group), and a mercapto group.
In R3, examples of the alkoxy group include C _1-4 alkoxy groups such as methoxy and ethoxy groups.

In R3, examples of the acyloxy group include _C2-4 acyloxy groups such as acetyloxy and propionyloxy.

Among R3, a hydrolytic condensation group is preferable from the viewpoint of crosslinking of polymers by a condensation bond between hydrolytic condensation groups or a condensation bond between a hydrolytic condensation group and another polymer (for example, a hydroxyl group that is bonded to another polymer).
As the hydrolytic condensable group, for example, a hydroxyl group, a halogen atom (such as a chlorine atom), an alkoxy group, an acyloxy group, an aryloxy group (such as a phenoxy group), a mercapto group, etc. are preferable, and an alkoxy group and an acyloxy group are more preferable.

Specific examples of the silane coupling agent (B) include vinyl group-containing silanes {e.g., halosilanes having a vinyl group (e.g., vinyl mono- to trihalosilanes such as vinyltrichlorosilane), alkoxysilanes having a vinyl group [e.g., vinyl alkoxysilanes (e.g., vinyl mono- to trialkoxysilanes such as vinyltrimethoxysilane and vinyltriethoxysilane, preferably vinyl mono- to tri-C _1-4 alkoxysilanes), vinyl alkoxyalkoxysilanes (e.g., vinyl mono- to tri-(C _1-4 alkoxyC 1-4 alkoxy)silanes such as vinyltri(methoxyethoxy)silane and vinyltris(β-methoxyethoxy)silane), styryl group-containing silanes (e.g., styryl mono- to trialkoxysilanes such as p-styryltrimethoxysilane, preferably styryl mono- to tri-C _1-4 alkoxysilanes), _1-4 alkoxysilane), etc.]}, (meth)acryloyl group-containing silanes {for example, alkoxysilanes having a (meth)acryloyl group [for example, (meth)acryloxyalkyl mono- to trialkoxysilanes such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, etc., preferably (meth)acryloxyC2-4 alkylmono- to tri _{- C1-4} alkoxysilanes], hydroxysilanes having a (meth)acryloyl group [for example, (meth)acryloxyalkyl hydroxysilanes such as 3-(meth)acryloxypropylhydroxysilane, 3-(meth)acryloxypropylmethylhydroxysilane, etc., preferably (meth) _acryloxyC2-4 alkylhydroxysilanes]}, and the like.

Among these, from the viewpoint of improving the water resistance of the coating film, an alkoxysilane having a (meth)acryloyl group is preferred, a (meth) _{acryloxyalkyl} mono- to trialkoxysilane is more preferred, and a (meth)acryloxyC2-4 alkyl mono- to _triC1-4 alkoxysilane [for example, 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, etc.] is particularly preferred.

The silane coupling agent (B) may be used alone or in combination of two or more.

In the polymerization components, the proportion of the silane coupling agent (B) varies depending on the types of other monomers, but from the viewpoint of improving the water resistance of the coating film, it may be, for example, 0.01 mass % or more of the total polymerization components, preferably 0.05 mass % or more, more preferably 0.1 mass % or more, and particularly preferably 0.15 mass % or more.
In the polymerization components, the proportion of the silane coupling agent (B) may be, for example, 15 mass % or less, preferably 10 mass % or less, more preferably 5 mass % or less, and particularly preferably 3 mass % or less of the total polymerization components.

These upper and lower limit values may be appropriately combined to set an appropriate range (e.g., 0.05 to 10% by mass, etc.) (same for others).

In the polymerization components, the proportion of the silane coupling agent (B) varies depending on the types of other monomers, but from the viewpoint of improving the water resistance of the coating film, it may be, for example, 0.01 mol % or more of the total polymerization components, preferably 0.05 mol % or more, more preferably 0.1 mol % or more, and particularly preferably 0.15 mol % or more.
In the polymerization components, the proportion of the silane coupling agent (B) may be, for example, 15 mol % or less, preferably 10 mol % or less, more preferably 5 mol % or less, and particularly preferably 3 mol % or less of the total polymerization components.

These upper and lower limit values may be appropriately combined to set an appropriate range (e.g., 0.05 to 10 mol%) (same for others).

The silane coupling agent (B), which is a constituent unit of the polymerization component (polymer), has a silane functional group (silyl group) in the constituent unit, and can crosslink the polymers (a) together by the silyl group. The manner of such crosslinking is not particularly limited, and may be either intramolecular crosslinking or intermolecular crosslinking, or may be crosslinked in both of these manners.
The form of crosslinking may be, for example, a bond between silyl groups in the polymer (a) (intramolecular crosslinking), or a crosslink between a silyl group in the polymer (a) and a functional group other than a silyl group in the polymer (a) (for example, a hydroxyl group in a structural unit derived from a hydroxyl group-containing (meth)acrylate such as 2-hydroxyethyl (meth)acrylate described later) (intermolecular crosslinking).

Thus, the silane coupling agent (B) can crosslink the polymer (a), but the polymerization components of the (meth)acrylic polymer (a) may further contain a crosslinkable monomer other than the silane coupling agent (B).

(Crosslinking Monomer)
In the crosslinkable monomer, the crosslinking may be, for example, crosslinking by polymerization, or crosslinking by chemical reaction (for example, reaction with isocyanate, reaction with epoxy, hydrolysis silylation reaction, reaction with hydrazine, reaction with aziridine, etc.).

The crosslinking monomers may be used alone or in combination of two or more.

The crosslinking monomer can crosslink the polymer (a), but the manner of such crosslinking is not particularly limited and can be appropriately selected depending on the type of crosslinking monomer, etc., and may be either intramolecular crosslinking or intermolecular crosslinking, or may be crosslinked in both of these manners.

Crosslinkable monomers that can be crosslinked by polymerization include, for example, compounds that have two or more polymerizable double bonds.

Examples of the compound having two or more polymerizable double bonds include diol di(meth)acrylates {e.g., alkanediol di(meth)acrylates [e.g., ethylene glycol di(meth)acrylate, 1,3-butanediol di(meth)acrylate, 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, and other C _2-10 alkanediol di(meth)acrylate, etc.], polyalkylene glycol di(meth)acrylates [e.g. diethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, polypropylene glycol di(meth)acrylate, etc.], alkylene oxide modified alkylene glycol di(meth)acrylates [e.g. ethylene oxide modified 1,6-hexanediol di(meth)acrylate, propylene oxide modified neopentyl glycol di(meth)acrylate], di(meth)acrylates of aromatic diols or alkylene oxide adducts thereof [e.g. bisphenol A di(meth)acrylate, ethoxylated bisphenol A di(meth)acrylate], etc.}, poly(meth)acrylates of polyols having three or more hydroxy groups {e.g. pentaerythritol di- or tetra(meth)acrylates [e.g. pentaerythritol monohydroxytri(meth)acrylate, acrylate, pentaerythritol tetra(meth)acrylate, etc.], dipentaerythritol di- to hexa(meth)acrylate [e.g., dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol (monohydroxy)penta(meth)acrylate, etc.], trimethylolpropane di- to tri(meth)acrylate [e.g., trimethylolpropane tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, poly(meth)acrylates of C 3-10 polyols such as di(meth)acrylate (e.g., ditrimethylolpropane triethoxy tri(meth)acrylate, ethylene oxide modified trimethylolpropane tri(meth)acrylate), ditrimethylolpropane di- to tetra(meth)acrylate (e.g., ditrimethylolpropane tetra(meth)acrylate), glycerin di- to tri(meth)acrylate (e.g., ethoxylated glycerin tri(meth)acrylate, propylene _oxide modified glycerol tri(meth)acrylate), etc.); unsaturated hydrocarbons (e.g., alkadienes (e.g., C _4-10 alkadienes such as butadiene, isoprene, chloroprene, etc.); aromatic hydrocarbons (e.g., divinylbenzene, etc.); compounds having a plurality of allyl groups such as diallyl dicarboxylate (e.g., diallyl phthalate), triallyl isocyanurate, etc.

Examples of crosslinkable monomers that crosslink by chemical reaction include epoxy group-containing monomers, carbonyl group-containing monomers, aziridinyl group-containing monomers, and isocyanato group-containing monomers.

Examples of epoxy group-containing monomers include epoxy group-containing (meth)acrylates [for example, glycidyl (meth)acrylate, α-methyl glycidyl (meth)acrylate, glycidyloxyalkyl (meth)acrylates (for example, glycidyloxy C _2-4 alkyl (meth)acrylates such as 2-glycidyloxyethyl (meth)acrylate)], allyl glycidyl ether, and the like, but the present invention is not limited to these examples.
These epoxy group-containing monomers may be used alone or in combination of two or more kinds.

Examples of the carbonyl group-containing monomer include aldehydes having a polymerizable double bond (e.g., acrolein, formylstyrol, (meth)acryloxyalkylpropenal, etc.), ketones having a polymerizable double bond (e.g., vinyl ethyl ketone, etc.), and (meth)acrylates containing a carbonyl group [e.g., acetonyl (meth)acrylate, diacetone (meth)acrylate, 2-hydroxypropyl (meth)acrylate acetylacetate, butanediol-1,4-acrylate acetylacetate, 2-(acetoacetoxy)ethyl (meth)acrylate, etc.], but the present invention is not limited to these examples.
These carbonyl group-containing monomers may be used alone or in combination of two or more kinds.

Examples of the aziridinyl group-containing monomer include (meth)acryloylaziridine and aziridinyl group-containing (meth)acrylate (e.g., 2-aziridinylethyl (meth)acrylate), but the present invention is not limited to these examples.
These aziridinyl group-containing monomers may be used alone or in combination of two or more kinds.

Examples of the isocyanato group-containing monomer include isocyanato group-containing (meth)acrylates.
Examples of isocyanato group-containing (meth)acrylates include 2-acryloyloxyethyl isocyanate (product name: Karenz AOI (registered trademark) manufactured by Showa Denko K.K., etc.), 2-methacryloyloxyethyl isocyanate (product name: Karenz MOI (registered trademark) manufactured by Showa Denko K.K., etc.), 1,1-bis(acryloyloxymethyl)ethyl isocyanate (product name: Karenz BEI (registered trademark) manufactured by Showa Denko K.K., etc.), and 5-methacryloyloxy-3-oxypentyl isocyanate (product name: Karenz MOI-EG (registered trademark) manufactured by Showa Denko K.K., etc.), but the present invention is not limited to these examples.
These isocyanato group-containing monomers may be used alone or in combination of two or more kinds.

The crosslinking monomers may be used alone or in combination of two or more.

When the polymerization components contain a crosslinkable monomer, the proportion of the crosslinkable monomer in the entire polymerization components may be, for example, about 0.01 to 15% by mass, preferably about 0.05 to 10% by mass, and more preferably about 0.1 to 5% by mass.

(Other monomers)
The polymerization components of the (meth)acrylic polymer may contain other monomers in addition to the reactive emulsifier (A) and the silane coupling agent (B) (and further, the crosslinkable monomer).
Representative examples of the other monomer include aliphatic (meth)acrylates.

Examples of the aliphatic (meth)acrylate include alkyl (meth)acrylates [e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tert-butyl (meth)acrylate, sec-butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, nonyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, n-lauryl (meth)acrylate, tridecyl (meth)acrylate, and stearyl (meth)acrylate, etc. _1-20 alkyl (meth)acrylate], alkoxyalkyl (meth)acrylate [for example, alkoxyalkyl (meth)acrylate (for example, C _1-12 alkoxy C _1-12 alkyl methacrylate of 2-methoxyethyl (meth)acrylate, etc.)], and the like.

Aliphatic (meth)acrylates may be used alone or in combination of two or more.

Among these aliphatic (meth)acrylates, C _1-12 alkyl (meth)acrylates (for example, C 1-8 alkyl (meth)acrylates) such as methyl (meth)acrylate, n-butyl (meth)acrylate, tert-butyl (meth)acrylate, and 2 _- ethylhexyl (meth)acrylate are preferred, and 2-ethylhexyl (meth)acrylate is particularly preferred.

In the polymerization components, the proportion of aliphatic (meth)acrylates will vary depending on the types of other monomers, but the proportion of aliphatic (meth)acrylates in the entire polymerization components may be, for example, about 10 to 90% by mass, preferably 20 to 90% by mass, more preferably 25 to 80% by mass, and particularly preferably about 30 to 80% by mass.

In particular, when the polymerization components contain 2-ethylhexyl (meth)acrylate, the proportion of 2-ethylhexyl (meth)acrylate in the entire polymerization components may be, for example, 10% by mass or more (e.g., 10 to 90% by mass), preferably 20% by mass or more (e.g., 20 to 90% by mass), more preferably 25% by mass or more (e.g., 25 to 80% by mass), and particularly preferably 30% by mass or more (e.g., 30 to 80% by mass), although this depends on the types of other monomers.

Examples of monomers other than aliphatic (meth)acrylates include alicyclic monomers (monomers having an alicyclic group), hydroxyl group-containing (meth)acrylates, aromatic monomers (monomers having an aromatic group), acid group-containing monomers (or anionic group-containing monomers), fluorine atom-containing monomers, nitrogen atom-containing monomers, ultraviolet absorbing monomers, hindered amine monomers (ultraviolet light stable monomers), etc.

(Alicyclic monomers)
The alicyclic monomer includes a monomer having an alicyclic structure (for example, a C _4-20 cycloalkyl group, preferably a C _4-10 cycloalkyl group).
Specific examples of the alicyclic monomer include alicyclic (meth)acrylates [for example, cycloalkyl (meth)acrylates (for example, C _4-20 cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, preferably C _4-10 cycloalkyl (meth)acrylates), cycloalkylalkyl (meth)acrylates (for example, C 4-10 cycloalkyl C 1-4 alkyl (meth)acrylates such as cyclohexylmethyl (meth)acrylate, cyclohexylethyl (meth)acrylate, cyclohexylpropyl (meth)acrylate, and 4 _- methylcyclohexylmethyl (meth)acrylate), and crosslinked _cyclic (meth)acrylates (for example, isobornyl (meth)acrylate, adamantyl (meth)acrylate, and the like)].

Among the alicyclic monomers, C _4-20 cycloalkyl (meth)acrylates are preferred, C _4-10 cycloalkyl (meth)acrylates are more preferred, and isobornyl (meth)acrylate and cyclohexyl (meth)acrylate are even more preferred.

Alicyclic monomers may be used alone or in combination of two or more.

When the polymerization components contain an alicyclic monomer, the proportion of the alicyclic monomer in the entire polymerization components may be, for example, about 5 to 80% by mass, preferably 10 to 70% by mass, more preferably 15 to 65% by mass, and particularly preferably about 20 to 60% by mass.

In addition, when the polymerization components contain an aliphatic (meth)acrylate and an alicyclic monomer, the ratio of these may be aliphatic (meth)acrylate/alicyclic monomer (mass ratio) = 95/5 to 5/95 (e.g., 90/10 to 10/90), preferably 80/20 to 20/80, and more preferably about 80/20 to 40/60.

(Hydroxyl-containing (meth)acrylate)
Examples of the hydroxyl group-containing (meth)acrylate include hydroxyalkyl (meth)acrylates [for example, hydroxy C _2-10 alkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, preferably hydroxy C _2-6 alkyl (meth)acrylate, more preferably hydroxy C _2-4 alkyl (meth)acrylate], and (meth)acrylates of polyols having three or more hydroxy groups [for example, (meth)acrylates of tri- to hexahydroxy C _3-10 polyols such as glycerin mono(meth)acrylate].

The hydroxyl group-containing (meth)acrylates may be used alone or in combination of two or more.

Among hydroxyl group-containing (meth)acrylates, 2-hydroxyethyl (meth)acrylate and glycerin mono(meth)acrylate are preferred, with 2-hydroxyethyl (meth)acrylate being more preferred.

When the polymerization components contain a hydroxyl group-containing (meth)acrylate, the proportion of the hydroxyl group-containing (meth)acrylate in the total polymerization components may be, for example, about 0.1 to 20% by mass, preferably 0.3 to 10% by mass, more preferably 0.5 to 8% by mass, and particularly preferably about 1 to 5% by mass.

In addition, when the polymerization components contain an aliphatic (meth)acrylate and/or an alicyclic monomer, and a hydroxyl group-containing (meth)acrylate, the proportion of the hydroxyl group-containing (meth)acrylate may be, for example, about 0.1 to 20 parts by mass, preferably 0.3 to 15 parts by mass, more preferably 0.5 to 10 parts by mass, and particularly preferably about 1 to 8 parts by mass, per 100 parts by mass of the aliphatic (meth)acrylate and/or alicyclic monomer.

(Aromatic Monomer)
Examples of aromatic monomers include styrene monomers [for example, styrene, α-alkylstyrenes (for example, α-C _1-4 alkylstyrenes such as α-methylstyrene), alkylstyrenes (for example, C _1-4 alkylstyrenes such as vinyltoluene), halostyrenes (for example, chlorostyrene), etc.], aromatic (meth)acrylates [for example, aryl (meth)acrylates (for example, C _6-10 aryl (meth)acrylates such as phenyl (meth)acrylate), aralkyl (meth)acrylates (for example, C _6-10 aryl C _1-4 alkyl (meth)acrylates such as benzyl (meth)acrylate and phenethyl (meth)acrylate), aryloxyalkyl methacrylates (for example, C _6-10 aryloxy C _1-4 alkyl methacrylates such as phenoxyethyl methacrylate), etc.].

Among aromatic monomers, styrene monomers are preferred.

Aromatic monomers may be used alone or in combination of two or more.

When the polymerization components contain aromatic monomers, the proportion of aromatic monomers in the total polymerization components may be, for example, about 0.1 to 50% by mass, preferably 0.5 to 40% by mass, and more preferably 1 to 35% by mass (e.g., 10 to 35% by mass, etc.).

(Acid Group-Containing Monomer)
Examples of the acid group-containing monomer (anionic group-containing monomer) include carboxylic acid group-containing monomers [e.g., unsaturated monocarboxylic acids (e.g., aliphatic unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid), unsaturated dicarboxylic acids (e.g., aliphatic unsaturated monocarboxylic acids such as maleic acid and fumaric acid)], and sulfonic acid group-containing monomers [e.g., styrene-based monomers (e.g., styrene sulfonic acid)].
The acid group-containing monomer may be anionized (or may form a salt).

The acid group-containing monomers may be used alone or in combination of two or more.

When the polymerization components contain an acid group-containing monomer, the proportion of the acid group-containing monomer in the total polymerization components may be, for example, about 0.01 to 10% by mass, preferably 0.02 to 5% by mass, and more preferably 0.05 to 3% by mass.

(Fluorine Atom-Containing Monomer)
Examples of the fluorine atom-containing monomer include fluorine atom-containing acrylic monomers [for example, fluoroalkyl (meth)acrylates (for example, fluoro C _1-10 alkyl (meth)acrylates such as trifluoroethyl (meth)acrylate, tetrafluoropropyl (meth)acrylate, octafluoropentyl (meth)acrylate, and preferably fluoro C _2-6 alkyl (meth)acrylates)].

The fluorine atom-containing monomers may be used alone or in combination of two or more.

When the polymerization components contain a fluorine atom-containing monomer, the proportion of the fluorine atom-containing monomer in the entire polymerization components may be, for example, about 0.01 to 10 mass%, preferably 0.02 to 5 mass%, and more preferably about 0.03 to 3 mass%.

(Nitrogen Atom-Containing Monomer)
Examples of the nitrogen atom-containing monomer include (meth)acrylamide compounds {e.g., (meth)acrylamide, N-substituted (meth)acrylamide [e.g., N-alkyl(meth)acrylamide (e.g., N,N-diC _1-4 alkyl(meth)acrylamide such as N,N-dimethyl(meth)acrylamide; N,N-dimethylaminopropyl(meth)acrylamide, etc.)]} and nitrogen atom-containing (meth)acrylate compounds {e.g., N-substituted aminoalkyl(meth)acrylates [e.g., N,N-diC _1-4 alkylamino C _2-4 alkyl(meth)acrylates such as dimethylaminoethyl(meth)acrylate, diethylaminoethyl(meth)acrylate]}.

The nitrogen atom-containing monomers may be used alone or in combination of two or more.

When the polymerization components contain a nitrogen atom-containing monomer, the proportion of the nitrogen atom-containing monomer in the entire polymerization components may be, for example, about 0.01 to 10 mass%, preferably 0.02 to 5 mass%, and more preferably 0.03 to 3 mass%.

(UV absorbing monomer)
Examples of the ultraviolet absorbing monomer (monomer having an ultraviolet absorbing group) include benzotriazole-based ultraviolet absorbing monomers and benzophenone-based ultraviolet absorbing monomers.

Benzotriazole-based ultraviolet absorbing monomers include benzotriazole-based ultraviolet absorbers having a polymerizable group (e.g., a (meth)acryloyl group), such as 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-5-tert-butyl-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxymethylphenyl]-5-tert-butyl-2H-benzotriazole, 5'-(meth)acryloylaminomethyl-5'-tert-octylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxypropylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyhexylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-3'-tert-butyl-5'-(meth)acryloyloxyethylphenyl]-5-chloro-2H-benzotriazole, 2-[2'-hydroxy-5'-ter Examples include t-butyl-3'-(meth)acryloyloxyethylphenyl]-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-chloro-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-cyano-2H-benzotriazole, 2-[2'-hydroxy-5'-(meth)acryloyloxyethylphenyl]-5-tert-butyl-2H-benzotriazole, and 2-[2'-hydroxy-5'-(β-(meth)acryloyloxyethoxy)-3'-tert-butylphenyl]-4-tert-butyl-2H-benzotriazole.

Benzophenone-based UV-absorbing monomers include benzophenone-based UV absorbers having a polymerizable group (e.g., a (meth)acryloyl group), such as 2-hydroxy-4-(meth)acryloyloxybenzophenone, 2-hydroxy-4-[2-hydroxy-3-(meth)acryloyloxy]propoxybenzophenone, 2-hydroxy-4-[2-(meth)acryloyloxy]ethoxybenzophenone, 2-hydroxy-4-[3-(meth)acryloyloxy-2-hydroxypropoxy]benzophenone, and 2-hydroxy-3-tert-butyl-4-[2-(meth)acryloyloxy]butoxybenzophenone.

The ultraviolet absorbing monomers may be used alone or in combination of two or more.

When the polymerization components contain an ultraviolet absorbing monomer, the proportion of the ultraviolet absorbing monomer in the entire polymerization components may be, for example, about 0.01 to 10 mass%, preferably 0.02 to 5 mass%, and more preferably about 0.03 to 3 mass%.

(Hindered amine monomer)
Examples of hindered amine monomers (ultraviolet ray stable monomers, light stabilizers having polymerizable groups, light-stable monomers) include 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyl-1-methoxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, and the like.

Hindered amine monomers may be used alone or in combination of two or more.

When the polymerization components contain a hindered amine monomer, the proportion of the hindered amine monomer in the entire polymerization components may be, for example, about 0.01 to 20% by mass, preferably about 0.05 to 10% by mass, and more preferably about 0.1 to 5% by mass.

Among the other monomers described above, it is preferable to include one or more selected from alicyclic monomers [for example, C _4-20 cycloalkyl (meth)acrylates (preferably, C _4-10 cycloalkyl (meth)acrylates, more preferably isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, etc.)] and aromatic monomers {for example, styrene monomers [for example, styrene, α-alkylstyrenes (for example, α-C _1-4 alkylstyrene, etc.), alkylstyrenes (for example, C _1-4 alkylstyrene, etc.), halostyrenes (for example, chlorostyrene, etc.)]}, and it is particularly preferable to include one or more selected from cyclohexyl methacrylate and styrene.

The other monomers exemplified above may be used alone or in combination of two or more.

The emulsion may be prepared, typically by reaction in the presence of an emulsifier, as described below.
The emulsifier may be a reactive emulsifier (A), or may contain, in addition to the reactive emulsifier (A), other emulsifiers (surfactants) that do not belong to the category of the reactive emulsifier (A).

The other emulsifiers may be any emulsifier that does not fall into the category of reactive emulsifier (A), and examples of such emulsifiers include anionic emulsifiers, nonionic emulsifiers, cationic emulsifiers (e.g., alkyl ammonium salts such as decyl ammonium chloride), amphoteric emulsifiers (e.g., betaine ester-type emulsifiers), etc.

Examples of anionic emulsifiers include alkyl sulfate salts such as ammonium dodecyl sulfate and sodium dodecyl sulfate; alkyl sulfonate salts such as ammonium dodecyl sulfonate and sodium dodecyl sulfonate; alkyl aryl sulfonate salts such as ammonium dodecyl benzene sulfonate and sodium dodecyl naphthalene sulfonate; polyoxyethylene alkyl sulfate salts; polyoxyethylene alkyl aryl sulfate salts; polyoxyethylene alkyl ether sulfate salts; dialkyl sulfosuccinate salts; aryl sulfonic acid-formalin condensates; and fatty acid salts such as ammonium laurate and sodium stearate.

Examples of nonionic emulsifiers include polyoxyethylene alkyl ethers, polyoxyethylene alkylaryl ethers, condensates of polyethylene glycol and polypropylene glycol, sorbitan fatty acid esters, polyoxyethylene sorbitan fatty acid esters, fatty acid monoglycerides, and condensates of ethylene oxide and aliphatic amines.

Other emulsifiers include polymeric emulsifiers. Examples of polymeric emulsifiers include anionic emulsifiers (poly(meth)acrylates such as sodium polyacrylate), nonionic emulsifiers (polyvinyl alcohol, polyvinylpyrrolidone, polyhydroxyalkyl(meth)acrylates such as polyhydroxyethyl acrylate), and polymers in which one or more of the monomers constituting these polymers are copolymerized components.

From the viewpoint of the coating film properties, the other emulsifier may be one having a reactive group (or a polymerizable group) (reactive emulsifier).
When the emulsion contains another reactive emulsifier, the other reactive emulsifier may be a polymerization component of the (meth)acrylic polymer (a) together with the reactive emulsifier (A).

Other reactive emulsifiers include, for example, anionic emulsifiers [e.g., propenyl-alkyl sulfosuccinate salts, (meth)acrylic acid polyoxyethylene sulfonate salts, (meth)acrylic acid polyoxyethylene phosphonate salts [e.g., Sanyo Chemical Industries, Ltd., product name: Eleminol RS-30, etc.], polyoxyethylene alkylpropenyl phenyl ether sulfonate salts [e.g., Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon HS-10, etc.], sulfonate salts of allyloxymethyl alkyloxy polyoxyethylene [e.g., Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon KH-10, etc.], sulfonate salts of propenyl nonyl phenyloxy polyoxyethylene [e.g., Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon BC-10, etc.], sulfonate salts of allyloxymethyl nonyl phenoxyethyl hydroxy polyoxyethylene [e.g., ADEKA Corporation, Product name: Adeka Reasoap SE-10, etc.), allyloxymethylalkoxyethylhydroxypolyoxyethylene sulfate salts (e.g., manufactured by ADEKA Corporation, product names: Adeka Reasoap SR-10, SR-30, etc.), bis(polyoxyethylene polycyclic phenyl ether) methacrylated sulfonate salts (e.g., manufactured by Nippon Nyukazai Co., Ltd., product name: Antox MS-60, etc.), etc.), nonionic emulsifiers (e.g., allyloxymethylalkoxyethylhydroxypolyoxyethylene (e.g., manufactured by ADEKA Corporation, product name: Adeka Reasoap ER-20, etc.), polyoxyethylene alkylpropenylphenyl ether (e.g., manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon RN-20, etc.), allyloxymethylnonylphenoxyethylhydroxypolyoxyethylene (e.g., manufactured by ADEKA Corporation, product name: Adeka Reasoap NE-10, etc.), etc.).

The other emulsifiers may be used alone or in combination of two or more types.

Among these other emulsifiers, anionic emulsifiers, particularly anionic reactive emulsifiers, may be preferably used.

When the emulsion contains other emulsifiers, the proportion of the other emulsifiers in the total polymerizable components may be, for example, about 30% by mass or less (e.g., 0.01 to 30% by mass), preferably 20% by mass or less (e.g., 0.01 to 20% by mass), more preferably 10% by mass or less (e.g., 0.01 to 10% by mass), and particularly preferably 5% by mass or less (e.g., 0.01 to 5% by mass).

The proportion of reactive emulsifier (A) in the entire emulsifier may be, for example, 10% by mass or more (e.g., 10 to 100% by mass, 10 to 90% by mass), preferably 40% by mass or more (e.g., 40 to 100% by mass, 40 to 90% by mass), more preferably 70% by mass or more (e.g., 70 to 100% by mass, 70 to 90% by mass), particularly preferably 90% by mass or more (e.g., 90 to 100% by mass), and most preferably 100% by mass.

The emulsion may have a monolayer structure (consisting of only one layer) or a multilayer structure (or core-shell structure) (consisting of an inner layer or an outer layer (outermost layer) and an inner layer).

When the emulsion has a multi-layer structure, the number of layers may be 2 or more, for example, 2 to 6, preferably 2 to 5, more preferably 2 to 4 (e.g., 2 to 3), and particularly 3.

When the emulsion has a multilayer structure, at least one of the outer layer (shell) and the inner layer (core) may be composed of the (meth)acrylic polymer (a) (emulsion), and the inner layer and the outer layer may be composed of different polymers (resins).
The (meth)acrylic polymer (a) (emulsion thereof) may constitute either the outer layer or the inner layer, but it is preferable that it constitutes at least the outer layer.
In addition, when either one of the outer layer or the inner layer is composed of a polymer (emulsion) other than the (meth)acrylic polymer (a), the polymerization component of such a polymer can be selected from the monomers exemplified above (e.g., other monomers exemplified above).

The multi-layer structure may also be composed of a hard layer and a soft layer (composed relatively).
In such a case, either the outer layer or the inner layer may be a hard layer, i.e., the outer layer may be a hard layer and the inner layer may be a soft layer, or the outer layer may be a soft layer and the inner layer may be a hard layer. In addition, when the inner layer is composed of multiple layers, the hard layer and the soft layer may be formed between the multiple inner layers.

From the viewpoint of improving the water resistance of the coating film, the mass ratio of the polymer constituting the inner layer to the polymer constituting the outer layer may be, for example, 95:5 to 5:95 (e.g., 90:10 to 10:90), preferably 88:12 to 12:88 (e.g., 85:15 to 15:85), or 95:5 to 20:80 (e.g., 90:10 to 30:70, preferably 88:12 to 40:60).

In particular, when the emulsion has a three-layer structure, the proportion of the first layer in the entire emulsion may be about 20 to 70% by mass (e.g., 30 to 60% by mass), the proportion of the second layer in the entire emulsion may be about 20 to 70% by mass (e.g., 30 to 60% by mass), and the proportion of the third layer in the entire emulsion may be about 20 to 70% by mass (e.g., 30 to 60% by mass).

The glass transition temperature of the (meth)acrylic polymer (a) constituting the emulsion may be, for example, −40° C. or higher (e.g., −40 to 80° C., −40 to 40° C., etc.), preferably −30° C. or higher (e.g., −30 to 80° C., −30 to 40° C., etc.), and more preferably −25° C. or higher (e.g., −25 to 80° C., −25 to 40° C., etc.).
In the case of an emulsion having a multi-layer structure, the glass transition temperature of all the polymers constituting the emulsion having a multi-layer structure may be within the above-mentioned range.

The glass transition temperature is calculated by using the glass transition temperature of a homopolymer of the monomer used in the monomer component constituting the polymer.
Formula (I): 1/Tg=Σ(Wm/Tgm)/100 (I)
(In the formula, Wm represents the content (mass%) of monomer m in the monomer components constituting the polymer, and Tgm represents the glass transition temperature (absolute temperature: K) of a homopolymer of monomer m.)
The temperature may be determined based on the Fox equation:

In addition, when the emulsion has a multi-layer structure, the glass transition temperature of the entire polymer constituting the multi-layer emulsion means the glass transition temperature calculated from the mass fraction of each monomer in all the monomer components used in the multi-stage emulsion polymerization and the glass transition temperature of the homopolymer of the corresponding monomer.

The glass transition temperatures of homopolymers are, for example, -70°C for homopolymers of 2-ethylhexyl acrylate, 83°C for homopolymers of cyclohexyl methacrylate, 100°C for homopolymers of styrene, 70°C for homopolymers of γ-methacryloxypropyltrimethoxysilane, 55°C for homopolymers of 2-hydroxyethyl methacrylate, 105°C for homopolymers of methyl methacrylate, 130°C for homopolymers of methacrylic acid, 107°C for homopolymers of tert-butyl methacrylate, approximately 130°C for homopolymers of 1,2,2,6,6-pentamethylpiperidyl methacrylate, 77°C for homopolymers of diacetone acrylamide, 55°C for homopolymers of glycerin monomethacrylate, 20°C for homopolymers of n-butyl methacrylate, and -56°C for homopolymers of n-butyl acrylate.

For monomers with unknown glass transition temperatures, such as special monomers and polyfunctional monomers, if the total amount of monomers with unknown glass transition temperatures in the monomer component is 10 mass% or less in mass fraction, the glass transition temperature may be determined using only monomers with known glass transition temperatures.

When the total amount of monomers with unknown glass transition temperatures in the monomer component exceeds 10% by mass, the glass transition temperature of the polymer may be determined by differential scanning calorimetry (DSC), differential thermal analysis (DTA), thermomechanical analysis (TMA), etc.

The weight average molecular weight of the (meth)acrylic polymer (a) constituting the emulsion may be, for example, 100,000 or more, preferably 300,000 or more, more preferably 550,000 or more, and particularly preferably 600,000 or more, from the viewpoint of improving the water resistance of the coating film.

The upper limit of the weight average molecular weight of the (meth)acrylic polymer (a) is not particularly limited, but is preferably 5 million or less from the viewpoint of improving film-forming properties, for example.

The weight average molecular weight may be measured (in terms of polystyrene) using, for example, gel permeation chromatography (e.g., Tosoh Corporation, product number: HLC-8120GPC, column: TSKgel G-5000HXL and TSKgel GMHXL-L in series).

The average particle size of the emulsion particles is not particularly limited, but may be, for example, 50 nm or more, preferably 100 nm or more, and from the viewpoint of coating film properties, may be, for example, 300 nm or less, preferably 250 nm or less.
The average particle size of the emulsion particles may typically be about 50 to 300 nm (eg, 60 to 250 nm), and preferably about 100 to 250 nm.

The average particle size of the emulsion particles may be the volume average particle size measured using a particle size distribution measuring device (manufactured by Particle Sizing Systems, product name: NICOMP Model 380) using the dynamic light scattering method.

The solid content (non-volatile content) of the particles (or solid content) in the emulsion may be preferably 30% by mass or more, more preferably 40% by mass or more, from the viewpoint of productivity, etc., and may be preferably 70% by mass or less, more preferably 60% by mass or less, from the viewpoint of improving handleability, etc.

The amount of non-volatile particles in the emulsion can be determined, for example, by weighing 1 g of the emulsion, drying it in a hot air dryer at 110° C. for 1 hour, and taking the resulting residue as the non-volatile content.
Formula: [Non-volatile content in emulsion (mass %)] = ([mass of residue] ÷ [1 g of emulsion]) × 100
It can be determined based on the following.

From the viewpoint of improving film-forming properties, the minimum film-forming temperature of the emulsion may be, for example, 60° C. or lower, preferably 50° C. or lower, and more preferably 40° C. or lower.
The minimum film-forming temperature of the emulsion can be adjusted, for example, by adjusting the glass transition temperature of the entire emulsion particle or the glass transition temperature of the outermost layer.

In this specification, the minimum film-forming temperature of an emulsion can be determined, for example, by applying a resin emulsion to a thickness of 0.2 mm with an applicator onto a glass plate placed on a thermal gradient tester, and measuring the temperature at which cracks appear.

The polymer content in the emulsion (content of (meth)acrylic polymer (a) or, in the case of a multi-layer structure, the total content of the polymers constituting the inner and outer layers) may be, for example, 20% by mass or more (e.g., 25 to 100% by mass), preferably 30% by mass or more (e.g., 35 to 90% by mass), and more preferably 40% by mass or more (e.g., 45 to 85% by mass) from the viewpoint of the coating film properties, etc.

(Method of producing emulsion)
The emulsion can be obtained by emulsion polymerization of the polymerization components (monomer components) in a solvent.

Examples of the solvent include aqueous solvents such as water and solvents containing water [eg, mixed solvents of water and alcohol (eg, C _1-4 alcohols such as methanol and ethanol)].
The solvents may be used alone or in combination of two or more.

Methods for emulsion polymerization of monomer components include, for example, a method in which the monomer components are mixed (dropped, etc.) into a solvent (solution) containing an emulsifier and polymerized, and a method in which previously emulsified monomer components are mixed (dropped, etc.) into a solvent and polymerized, but the present invention is not limited to only these methods.

The amount of solvent (medium) can be set appropriately taking into account the amount of non-volatile matter contained in the resulting emulsion.

The polymerization may be carried out in the presence of a polymerization initiator.
Examples of the polymerization initiator include azo compounds such as azobisisobutyronitrile, 2,2-azobis(2-methylbutyronitrile), 2,2-azobis(2,4-dimethylvaleronitrile), 2,2-azobis(2-diaminopropane)hydrochloride, 4,4-azobis(4-cyanovaleric acid), and 2,2-azobis(2-methylpropionamidine); persulfates such as potassium persulfate; and peroxides such as hydrogen peroxide, benzoyl peroxide, parachlorobenzoyl peroxide, lauroyl peroxide, and ammonium peroxide.
The polymerization initiators may be used alone or in combination of two or more.

When a polymerization initiator is used, the amount of polymerization initiator per 100 parts by mass of polymerization components is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, from the viewpoint of increasing the polymerization rate and reducing the amount of remaining unreacted monomer components, and is preferably 1 part by mass or less, more preferably 0.5 parts by mass or less, from the viewpoint of coating film properties, etc.

The method of adding the polymerization initiator is not particularly limited, but examples thereof include batch addition, divided addition, and continuous dropwise addition.
From the viewpoint of hastening the completion time of the polymerization reaction, a part of the polymerization initiator may be added to the reaction vessel before or after the completion of the addition of the polymerization components to the reaction system.

In addition, to promote the decomposition of the polymerization initiator, a suitable amount of a polymerization initiator decomposer, such as a reducing agent such as sodium hydrogen sulfite or a transition metal salt such as ferrous sulfate, may be added to the reaction system.

Additionally, additives such as chain transfer agents, such as compounds having a thiol group (e.g., tert-dodecyl mercaptan), pH buffers, chelating agents, and film-forming agents may be present in the reaction system as necessary.

The atmosphere during polymerization is not particularly limited, but may be an inert gas such as nitrogen gas from the viewpoint of polymerization efficiency, etc.

The polymerization temperature is not particularly limited, but may be, for example, 50 to 100°C, preferably 60 to 95°C. The polymerization temperature may be constant or may be changed during the polymerization reaction.

The polymerization time is not particularly limited and may be set appropriately depending on the progress of the polymerization reaction, but may be, for example, 1 hour or more (e.g., 1 to 24 hours), preferably 2 to 12 hours (e.g., 2 to 9 hours).

A multi-layer emulsion can be obtained by carrying out the emulsion polymerization exemplified above in multiple stages.

<Composition>
The present invention also includes a composition containing an emulsion of a (meth)acrylic polymer having as at least a polymerization component a reactive emulsifier (A) having a plurality of aromatic groups, and a urethane associative thickener.
The compositions of the present invention can be used in particular for coating applications.
In such a composition, the reactive emulsifier (A) may be any of the reactive emulsifiers exemplified above.

In addition, the composition may contain the above-mentioned monomers (e.g., silane coupling agent (B), crosslinking monomer, other monomers, etc.) as polymerization components of the (meth)acrylic polymer.

In addition, the (meth)acrylic polymer in the composition may be the (meth)acrylic polymer (a) exemplified above, and the emulsion in the composition may be the emulsion exemplified above.

As the urethane association type thickener, for example, a urethane resin can be suitably used. The urethane resin is preferably water-soluble.

It is preferable that the urethane resin has a hydrophobic portion (hydrophobic group) and a hydrophilic portion (hydrophilic group).

The bonding site of the hydrophobic group in the urethane-based resin is not particularly limited, and the hydrophobic group may be present at an end of the urethane-based resin, or at one end or both ends of the urethane-based resin, and it is preferable that the hydrophobic group be present at both ends.
Additionally, the hydrophobic groups can act as association sites.
For example, in a solvent (water or an aqueous solvent containing water), the hydrophobic group site (particularly, a terminal hydrophobic group) associates (physically bonds) with the surface of an emulsion particle of the (meth)acrylic polymer (a) and/or the hydrophobic groups associate with each other, thereby thickening the emulsion of the (meth)acrylic polymer (a).

Examples of the hydrophobic group include hydrocarbon groups (eg, C _1-30 aliphatic hydrocarbon groups, C _3-30 aliphatic hydrocarbon groups, etc.).

The bonding site of the hydrophilic group in the urethane resin is not particularly limited, and the hydrophilic group may be present in the main chain or in the side chain of the urethane polymer.

The hydrophilic portion (hydrophilic group) is not particularly limited, but examples thereof include a portion having an ether bond (e.g., an oxyalkylene unit such as polyoxyethylene). The portion having an ether bond may be, for example, a unit derived from a polyol, which is a structural unit of a urethane-based resin.

The urethane associative thickener may be one that is readily available commercially.

Examples of urethane associative thickeners include ADEKA NOL UH-420, ADEKA NOL UH-438, and ADEKA NOL UH-450VF (all trade names manufactured by ADEKA CORPORATION), but the present invention is not limited to these examples.
Among these, Adekanol UH-420 and the like are preferable.
The urethane association type thickeners may be used alone or in combination of two or more kinds.

In the composition, the mass ratio of the (meth)acrylic polymer:urethane associative thickener may be, for example, 100:0.01 to 100:1, preferably 100:0.1 to 100:0.8, and more preferably 100:0.15 to 100:0.5.
In the present invention, by using the reactive emulsifier (A), a coating material can be efficiently formed even if the blend ratio of the thickener to the (meth)acrylic polymer (active ingredient) is relatively small.

The composition may contain thickeners other than the urethane associative thickener.
The other thickener may be, for example, an acrylic resin that dissolves in water (alkali-soluble) by adding a base [for example, an acrylic resin that contains at least a unit derived from (meth)acrylic acid and a unit derived from an alkyl (meth)acrylate (for example, methyl (meth)acrylate)]. Such an acrylic resin can thicken the solution by dissolving in the alkaline solution.
Such an acrylic resin may have an association site (for example, the hydrophobic group in the urethane resin exemplified above).

Other thickening agents may be readily available commercially.
Other examples of thickeners include Acryset WR-507 and Acryset WR-650 (trade names, manufactured by Nippon Shokubai Co., Ltd.), but the present invention is not limited to these examples.
The other thickeners may be used alone or in combination of two or more kinds.

When the composition contains other thickeners, the mass ratio of the urethane associative thickener to the other thickeners may be, for example, 100:1 to 100:100, preferably 100:5 to 100:90, and more preferably 100:10 to 100:80.

The viscosity of the composition may be, for example, 1,000 to 20,000 mPa·s, preferably 1,500 to 10,000 mPa·s, and more preferably 2,000 to 8,000 mPa·s, as measured at 25°C using a BH type viscometer at a rotation speed of 20 rpm.

The composition may contain a solvent, or may be a composition in which the emulsion and thickener are dispersed (or dissolved) in the solvent.

As the solvent, the above-mentioned solvents can be used, and preferably, an aqueous solvent such as water or a solvent containing water [for example, a mixed solvent containing water and an alcohol (a lower alcohol such as methanol or ethanol)].
In particular, the composition may be a composition in which the emulsion and thickener are dispersed (or dissolved) in an aqueous solvent (aqueous composition).

In a composition containing a solvent, the total proportion of the emulsion and thickener can be appropriately selected depending on the application, but may be, for example, about 0.1 to 95% by mass, preferably 1 to 90% by mass, and more preferably 3 to 80% by mass.

The composition may contain other ingredients in addition to the ingredients described above (eg, emulsion and thickener).
Examples of other components include pigments (such as the pigments described below), pigment dispersants, suspending agents, UV absorbers, light stabilizers, film-forming aids, thickeners, surface conditioners, preservatives and antifungal agents, leveling agents, antifreeze agents, wetting agents, pH adjusters, and defoamers.
These components may be used alone or in combination of two or more.

The method for producing the composition is not particularly limited, and the composition can be produced, for example, by mixing the emulsion with a thickener (and, if necessary, a solvent or other components).

(Uses of the emulsion and composition)
The emulsion and composition of the present invention are particularly suitable for use in paints (coatings). Such emulsions and compositions may be used, for example, for surface finishing of substrates made of various materials (e.g., metal, glass, porcelain, concrete, siding boards, resins, etc.).

The emulsion and composition of the present invention can be particularly suitably used as a topcoat (or topcoat material, for example, a topcoat for interior materials (building materials) or exterior materials).

Exterior materials include, for example, various building materials (e.g., inorganic building materials such as flexible boards, calcium silicate boards, gypsum slag perlite boards, wood-chip cement boards, precast concrete boards, ALC boards, and gypsum boards; ceramic building materials such as roofing tiles and exterior wall materials). Ceramic building materials can be obtained, for example, by adding inorganic fillers, fibrous materials, and the like to a hydraulic adhesive, which is the raw material for the inorganic hardened body, molding the resulting mixture, and curing and hardening the resulting molded body.

A topcoat (water-based paint) is usually applied to the surface of such exterior materials (building materials) to impart a desired design, etc. More specifically, topcoats or topcoats (water-based paints) are used as paints (architectural and exterior paints) to protect buildings from external environments such as sunlight and wind and rain, and to give buildings beauty and design. The composition of the present invention can be suitably used as this topcoat or topcoat (water-based paint).

In particular, it can be used in exterior paints that are applied directly to the exterior walls (exterior materials) of buildings and dried and hardened in the natural environment (drying at room temperature).
A paint formed from the emulsion or composition of the present invention provides a paint film with excellent water resistance, and therefore can exhibit sufficient paint film strength even when used as such an exterior paint.

The state of the surface coating film formed using the above-mentioned exterior paints can be in various forms, ranging from transparent to colored semi-transparent to colored concealing, but the colored concealing state is particularly common for the purpose of concealing an undercoat coating layer formed on an exterior material or an old topcoat coating layer (for repair purposes).
Therefore, the coating composition (coating) may contain a pigment.

The pigment is not particularly limited, and any known pigment can be used.
The pigment may be a colorant or an extender pigment (filler).
Representative pigments include, for example, inorganic pigments (e.g., inorganic color pigments such as titanium oxide, iron oxide, aluminum, and pearl pigments), organic pigments (e.g., organic color pigments such as quinacridone, anthraquinone, perylene, diketopyrrolopyrrole, benzimidazolone, isoindolinone, anthrapyrimidine, phthalocyanine, threne, dioxazine, and carbon black), and extender pigments (e.g., calcium carbonate, barium sulfate, kaolin, mica, and talc).
The pigments may be used alone or in combination of two or more kinds.

It is particularly preferable to use at least titanium oxide, as this improves color hiding power and gives the coating surface a high gloss. The amount of pigment to be added may be, for example, 5 to 70 parts by weight, preferably 7 to 65 parts by weight, and more preferably 10 to 60 parts by weight, per 100 parts by weight of the solid content of the polymer component (or emulsion) in the coating film after drying.

When the composition of the present invention is used for coating (painting), it may be applied in a single layer by itself, or may be applied by overcoating two or more layers. When applying two or more layers, only some of the layers may be formed by the composition of the present invention, or all of the layers may be formed by the composition of the present invention. Examples of overcoating include a method in which a paint for a first layer (e.g., undercoat layer) is applied to a substrate that has been treated with a primer or sealer, and then dried, and a paint for a second layer (e.g., topcoat layer) is applied on top and dried, but the present invention is not limited to such a method. When applying the paint, for example, a spray, roller, brush, trowel, etc. can be used.

Next, the present invention will be described in more detail based on examples, but the present invention is not limited to these examples. In the following examples, "parts" means "parts by mass."

Example 1
Into a flask equipped with a dropping funnel, a stirrer, a nitrogen inlet tube, a thermometer and a reflux condenser was placed 475 parts of deionized water.
A pre-emulsion for dropping was prepared in a dropping funnel consisting of 465 parts of deionized water, 120 parts of a 25% aqueous solution of an emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: AQUALON AR-10), 333 parts of 2-ethylhexyl acrylate (2EHA), 460 parts of methyl methacrylate (MMA), 200 parts of styrene (St), 5 parts of 2-hydroxyethyl methacrylate (HEMA), and 2 parts of a silyl group-containing monomer (trade name: KBM-503). 100 parts of the pre-emulsion was added to the flask, and the temperature was raised to 80° C. while slowly blowing in nitrogen gas. Polymerization was initiated by adding 60 parts of a 5% aqueous solution of potassium persulfate to the flask.

Next, the remaining portion of the pre-emulsion for dropping was dropped evenly into the flask over a period of 180 minutes. After dropping was completed, the contents of the flask were maintained at 80°C for 60 minutes, and 25% aqueous ammonia was added to the flask to adjust the pH to 8-10, and the polymerization reaction was terminated.

The resulting reaction liquid was cooled to room temperature and then filtered through a 300 mesh (JIS mesh, the same applies below) wire mesh to obtain a resin emulsion.

(Examples 2 to 6)
A resin emulsion was obtained in the same manner as in Example 1, except that the types and blending ratios of the monomers were as shown in Table 1.
In Table 1, BA represents butyl acrylate, and AA represents acrylic acid.
The emulsifier SR-10 used in Example 3 is manufactured by ADEKA CORPORATION and has the trade name ADEKA REASOAP SR-10 (allyloxymethylalkoxyethyl polyoxyethylene sulfate).
The emulsifier NF-08 used in Example 4 is manufactured by Daiichi Kogyo Seiyaku Co., Ltd. and has the trade name Hitenol NF-08 (polyoxyethylene alkyl ether sulfate).

(Example 7)
Into a flask equipped with a dropping funnel, a stirrer, a nitrogen inlet tube, a thermometer and a reflux condenser, 461 parts of deionized water was placed.
A pre-emulsion for dropping was prepared in a dropping funnel consisting of 59 parts of deionized water, 80 parts of a 25% aqueous solution of an emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon AR-10), and 200 parts of styrene. 40 parts of the pre-emulsion was added to the flask, and the temperature was raised to 80° C. while slowly blowing in nitrogen gas. Polymerization was initiated by adding 60 parts of a 5% aqueous solution of potassium persulfate to the flask.
The remaining portion of the pre-emulsion was then dripped evenly into the flask over a period of 60 minutes. After the dripping was completed, the contents of the flask were maintained at 80° C. for 60 minutes.

Then, a second-stage pre-emulsion consisting of 382 parts of deionized water, 80 parts of a 25% aqueous solution of an emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon AR-10), 240 parts of 2-ethylhexyl acrylate, 553 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, and 2 parts of a silyl group-containing monomer (product name: KBM-503) was added dropwise uniformly into the flask over a period of 60 minutes. After the addition was completed, the contents of the flask were maintained at 80°C for 60 minutes.

Finally, 25% ammonia water was added to the flask to adjust the pH to 8-10, and the polymerization reaction was terminated. The resulting reaction liquid was cooled to room temperature and then filtered through a 300 mesh (JIS mesh, the same applies below) wire mesh to obtain a resin emulsion.

(Example 8)
Into a flask equipped with a dropping funnel, a stirrer, a nitrogen inlet tube, a thermometer and a reflux condenser was placed 435 parts of deionized water.
A pre-emulsion for dropping was prepared in a dropping funnel consisting of 59 parts of deionized water, 80 parts of a 25% aqueous solution of an emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon AR-10), and 200 parts of styrene. 40 parts of the pre-emulsion was added to the flask, and the temperature was raised to 80° C. while slowly blowing in nitrogen gas. Polymerization was initiated by adding 60 parts of a 5% aqueous solution of potassium persulfate to the flask.
The remaining portion of the pre-emulsion was then dripped evenly into the flask over a period of 60 minutes. After the dripping was completed, the contents of the flask were maintained at 80° C. for 60 minutes.

Then, a second-stage pre-emulsion consisting of 166 parts of deionized water, 80 parts of a 25% aqueous solution of an emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon AR-10), 212 parts of 2-ethylhexyl acrylate, 180 parts of methyl methacrylate, 5 parts of 2-hydroxyethyl methacrylate, and 3 parts of a silyl group-containing monomer (product name: KBM-503) was added dropwise uniformly into the flask over a period of 60 minutes. After the addition was completed, the contents of the flask were maintained at 80°C for 60 minutes.

Next, a third-stage pre-emulsion consisting of 166 parts of deionized water, 80 parts of a 25% aqueous solution of an emulsifier (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., product name: Aqualon AR-10), 167 parts of 2-ethylhexyl acrylate, 220 parts of methyl methacrylate, 10 parts of acrylic acid, and 3 parts of a silyl group-containing monomer (product name: KBM-503) was added dropwise uniformly into the flask over a period of 60 minutes. After the addition was completed, the contents of the flask were maintained at 80°C for 60 minutes.

Finally, 25% ammonia water was added to the flask to adjust the pH to 8-10, and the polymerization reaction was terminated. The resulting reaction liquid was cooled to room temperature and then filtered through a 300 mesh (JIS mesh, the same applies below) wire mesh to obtain a resin emulsion.

(Example 9)
A resin emulsion was obtained in the same manner as in Example 8, except that the types and blending ratios of the monomers were as shown in Table 1.

(Example 10)
A resin emulsion was obtained in the same manner as in Example 1, except that the types and blending ratios of the monomers were as shown in Table 1.

(Comparative Example 1)
A resin emulsion was obtained using the method described in Example 1 of Patent Document 1.

(Reference Example 1)
A resin emulsion was obtained in the same manner as in Example 1, except that Adeka Reasoap SR-10 (allyloxymethylalkoxyethyl polyoxyethylene sulfate), manufactured by ADEKA CORPORATION, was used instead of Aqualon AR-10 as the emulsifier.

(Reference Examples 2 to 3)
A resin emulsion was obtained in the same manner as in Example 1, except that Adeka Reasoap SR-10 was used as the emulsifier instead of Aqualon AR-10, and the types and blending ratios of the monomers were as shown in Table 2.

(Reference Example 4)
A resin emulsion was obtained in the same manner as in Example 1, except that Aqualon BC-10 (a sulfonate salt of propenylnonylphenyloxypolyoxyethylene) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was used as the emulsifier instead of Aqualon AR-10.

(Reference Example 5)
A resin emulsion was obtained in the same manner as in Example 1, except that Aqualon KH-10 (a sulfonate salt of allyloxymethylalkyloxypolyoxyethylene) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was used as the emulsifier instead of Aqualon AR-10.

(Reference Example 6)
A resin emulsion was obtained in the same manner as in Example 1, except that a product named Hitenol NF-08 (polyoxyethylene alkyl ether sulfate) manufactured by Daiichi Kogyo Seiyaku Co., Ltd. was used as the emulsifier instead of Aqualon AR-10.

The physical properties of the resulting resin emulsion were measured as follows.
[Glass transition temperature (Tg)]
The glass transition temperature is calculated by using the glass transition temperature of the homopolymer of the monomer used in the monomer component constituting the polymer.
Formula (I): 1/Tg=Σ(Wm/Tgm)/100 (I)
(In the formula, Wm represents the content (mass%) of monomer m in the monomer components constituting the polymer, and Tgm represents the glass transition temperature (absolute temperature: K) of a homopolymer of monomer m.)
The temperature was calculated based on the Fox equation:

In addition, when the emulsion has a multi-layer structure, the glass transition temperature of the entire polymer constituting the multi-layer emulsion was calculated from the mass fraction of each monomer in all the monomer components used in the multi-stage emulsion polymerization and the glass transition temperature of the homopolymer of the corresponding monomer.

[Solid content (NV)]
The non-volatile content (solid content) of the emulsion was determined by weighing 1 g of the emulsion, drying it in a hot air dryer at 110° C. for 1 hour, and taking the resulting residue as the non-volatile content.
Formula: [Non-volatile content in emulsion (mass %)] = ([mass of residue] ÷ [1 g of emulsion]) × 100
It was calculated based on the above.

[viscosity]
The viscosity was measured at 25° C. at a rotation speed of 20 rpm using a BH type viscometer (manufactured by Tokyo Keiki Co., Ltd.).

[TI]
The viscosity at a rotation speed of 2 rpm using a BH type viscometer was divided by the viscosity at 20 rpm to obtain the thixotropic index (TI).
TI=viscosity (2 rpm)/viscosity (20 rpm)

[Volume average particle size]
The average particle size (volume average particle size) of the emulsion particles was measured using a particle size distribution measuring device (manufactured by Particle Sizing Systems, trade name: NICOMP Model 380) by dynamic light scattering.

[Minimum film forming temperature (MFT)]
A resin emulsion was applied to a glass plate placed on a thermal gradient tester (manufactured by Tester Sangyo Co., Ltd.) with an applicator to a thickness of 0.2 mm, and the temperature at which cracks appeared was determined as the minimum film-forming temperature. It was decided.

The resulting resin emulsion was then evaluated using the following methods.

[Evaluation method for enamel coating gloss]
(1) Preparation of pigment paste 210 parts by mass of deionized water, 60 parts by mass of dispersant [manufactured by Kao Corporation, trade name: Demol EP, dispersant (solid content) concentration 25% by mass aqueous solution], 50 parts by mass of dispersant [manufactured by Daiichi Kogyo Seiyaku Co., Ltd., trade name: Discoat N-14, dispersant (solid content) concentration 30% by mass aqueous solution], 10 parts by mass of wetting agent [manufactured by Kao Corporation, trade name: Emulgen LS-106, wetting agent (solid content) concentration 100% by mass], 60 parts by mass of propylene glycol, 1000 parts by mass of titanium oxide [manufactured by Ishihara Sangyo Kaisha, Ltd., product number: CR-95], and 200 parts by mass of glass beads (diameter: 1 mm) were prepared by stirring with a homodisper at a rotation speed of 3000 rpm for 60 minutes. Thereafter, the mixture was filtered through a 60-mesh wire screen to remove the glass beads to obtain a pigment paste.

(2) Preparation of enamel paint and thickening response 7 parts by mass of 2,2,4-trimethyl-1,3-pentanediol isobutyrate [manufactured by JNC Corporation, product number: CS-12] as a film-forming assistant was added to 100 parts by mass of the above-mentioned aqueous resin dispersion, and the mixture was stirred for 10 minutes at a rotation speed of 1500 rpm with a homodisper. While continuing the stirring, 42 parts by mass of the above-mentioned pigment paste was added. The amount of the pigment paste added was adjusted so that the amount of pigment was 14 volume % (40 mass %) with respect to the total amount of nonvolatile content. Furthermore, an appropriate amount of dilution water was added so that the amount of nonvolatile content was 50 mass %, and 0.3 mass % of a silicone-based defoamer [manufactured by San Nopco Ltd., product name: SN Defoamer 777] with respect to the total amount of the paint was added to the mixture. A 5% by mass aqueous solution of a thickener (manufactured by ADEKA Corporation, product name: Adekanol UH-420) was added to the mixture so that the viscosity at 25° C. at a rotation speed of 20 rpm using a BH type viscometer (manufactured by Tokyo Keiki Co., Ltd.) was 4500 mPa·s. The mixture was then further stirred at 1500 rpm for 30 minutes to evaluate the amount of thickener required (unit: g).

[Coating film strength after immersion in water]
To 100 parts by mass of the above aqueous resin dispersion, 7 parts by mass of 2,2,4-trimethyl-1,3-pentanediol isobutyrate (manufactured by JNC Corporation, product number: CS-12) was added as a film-forming aid, and the mixture was used as a clear coating material.
The clear paint was applied to a glass plate (length: 150 mm, width: 70 mm, thickness: 2 mm) using a 10 mil applicator and dried for one week in the atmosphere at 23° C. to obtain a clear coating film. The obtained coating film was immersed (submerged) in water adjusted to 25° C. and scratched with a fingernail to evaluate the coating film strength according to the following criteria.
⊚: Slight scratches, but no lifting or peeling.
○: Slight scratches, but some lifting or peeling occurs.
×: Lifting or peeling occurs.

The evaluation results of the examples are shown in Table 1, and the evaluation results of the comparative examples and reference examples are shown in Table 2.

As is clear from the results in Table 1 above, the coating films of the emulsions of Examples 1 to 9 exhibited excellent water resistance, and the coating film strength after immersion in water was also excellent.
Furthermore, the emulsions of the examples enabled a reduction in the amount of thickener added to the paint.

The present invention can provide emulsions and compositions that are useful for applications such as paints.

Claims (14)

A coating composition comprising: an emulsion of a (meth)acrylic polymer having as polymerization components at least a reactive emulsifier (A) having a plurality of aromatic groups and a silane coupling agent (B) having a polymerizable unsaturated bond group, the proportion of the reactive emulsifier (A) being 0.1 to 10 mass% relative to all polymerization components; the proportion of the silane coupling agent (B) being 0.05 to 10 mass% relative to all polymerization components; the (meth)acrylic polymer having a glass transition temperature of -40 to 80°C; and the proportion of the reactive emulsifier (A) in all emulsion being 90 mass% or more (excluding cases where the (meth)acrylic polymer is a (meth)acrylic polymer having as polymerization components all of sodium p-styrenesulfonate, glycidyl methacrylate, and 3-methacryloxypropyltriethoxysilane); and a urethane association type thickener . A coating composition comprising: an emulsion of a (meth)acrylic polymer having as at least polymerization components a reactive emulsifier (A) having a plurality of aromatic groups and a silane coupling agent (B) having a polymerizable unsaturated bond group, the proportion of the reactive emulsifier (A) being 0.1 to 10 mass % relative to all polymerization components, the proportion of the silane coupling agent (B) being 0.05 to 10 mass % relative to all polymerization components, the (meth)acrylic polymer having a glass transition temperature of -40 to 80°C, the emulsion containing another emulsifier not belonging to the category of the reactive emulsifier (A), the other emulsifier containing an anionic emulsifier (excluding cases where the (meth)acrylic polymer is a (meth)acrylic polymer containing all of sodium p-styrenesulfonate, glycidyl methacrylate, and 3-methacryloxypropyltriethoxysilane as polymerization components); and a urethane associative thickener . an emulsion of a (meth)acrylic polymer, comprising at least a reactive emulsifier (A) having a plurality of aromatic groups and a silane coupling agent (B) having a polymerizable unsaturated bond group as polymerization components;
The proportion of the reactive emulsifier (A) is 0.1 to 10% by mass based on the total polymerization components;
The ratio of the silane coupling agent (B) is 0.05 to 10 mass% based on the total polymerization components,
the polymerization component further comprises an aliphatic (meth)acrylate and a hydroxyl group-containing (meth)acrylate;
The aliphatic (meth)acrylate comprises 2-ethylhexyl (meth)acrylate;
the ratio of the hydroxyl group-containing (meth)acrylate is 0.1 to 20 parts by mass relative to 100 parts by mass of the aliphatic (meth)acrylate;
A coating composition comprising an emulsion in which the proportion of 2-ethylhexyl (meth)acrylate in all polymerization components is 10 to 90 mass %, and a urethane association type thickener . The composition according to claim 2, wherein the anionic emulsifier comprises at least one selected from propenyl-alkyl sulfosuccinate salts, polyoxyethylene sulfonate (meth)acrylate salts, polyoxyethylene phosphonate (meth)acrylate salts, polyoxyethylene alkylpropenyl phenyl ether sulfonate salts, sulfonate salts of allyloxymethyl alkyloxy polyoxyethylene, sulfonate salts of propenyl nonyl phenyloxy polyoxyethylene, sulfonate salts of allyloxymethyl nonyl phenoxy ethyl hydroxy polyoxyethylene, allyloxymethyl alkoxyethyl hydroxy polyoxyethylene sulfate salts, and bis(polyoxyethylene polycyclic phenyl ether) methacrylated sulfonate salts . The composition according to any one of claims 1 to 4, wherein the reactive emulsifier (A) comprises a reactive emulsifier represented by the following formula (1):
(In the formula, D represents the following formula (D-1) or (D-2), A represents an alkylene group having 2 to 4 carbon atoms, T represents a hydrogen atom or _-SO3M (M represents a hydrogen atom, an alkali metal atom, an alkaline earth metal atom or _NH4 ), l represents 1 to 2, m represents 1 to 3, and n represents 1 to 1000.)
(In the formula, R ¹ represents a hydrogen atom or a methyl group.) 6. The composition according to claim 1, wherein the polymerization components further comprise one or more monomers selected from the group consisting of monomers having an alicyclic group and monomers having an aromatic group. The composition according to any one of claims 1 to 6, wherein the proportion of the emulsifier other than the reactive emulsifier (A) is 5 mass % or less based on the total polymerization components. The composition according to any one of claims 3 to 7, wherein the (meth)acrylic polymer has a glass transition temperature of -40 to 80°C. A coating composition comprising an emulsion of a (meth)acrylic polymer having at least a reactive emulsifier (A) having multiple aromatic groups and a silane coupling agent (B) having a polymerizable unsaturated bond group as polymerization components, the proportion of the reactive emulsifier (A) in the entire emulsion being 90 mass% or more (excluding cases where the (meth)acrylic polymer has sodium p-styrenesulfonate, glycidyl methacrylate, and 3-methacryloxypropyltriethoxysilane as polymerization components), and a urethane association type thickener. An emulsion of a (meth)acrylic polymer having at least a reactive emulsifier (A) having multiple aromatic groups and a silane coupling agent (B) having a polymerizable unsaturated bond group as polymerization components, which contains other emulsifiers not belonging to the category of reactive emulsifier (A), and the other emulsifiers contain an anionic emulsifier (excluding cases where the (meth)acrylic polymer has all of sodium p-styrenesulfonate, glycidyl methacrylate, and 3-methacryloxypropyltriethoxysilane as polymerization components), and a coating composition containing a urethane association type thickener. A paint comprising the composition according to any one of claims 1 to 10 . A coating film formed from the coating material according to claim 11 . A building having the coating film according to claim 12 . A building material having the coating film according to claim 12 .