JPH0477565A - Aqueous coating composition - Google Patents

Abstract

PURPOSE:To provide the subject composition having good storage stability and giving coating films having excellent solvent resistance, excellent water proofness and high moisture permeability and employed in coating concrete structures, etc., by employing a polymer emulsion containing a polysiloxane in the particles as a vehicle. CONSTITUTION:The objective composition employs as a vehicle a polymer emulsion obtained by emulsion-polymerizing (C) an alpha,beta-ethylenic unsaturated monomer having a reactive polar group (e.g. amino or carboxy) reacting with the reactive polar group of a component A and (D) a copolymerizable alpha,beta- ethylenic unsaturated monomer in the presence of an emulsified polymer, the emulsified polymer being prepared by emulsion-polymerizing (A) 100pts.wt. of an alpha,beta-ethylenic monomer in the presence of (B) 5-100pts.wt. of a polysiloxane having a reactive polar group (e.g. one or more of epoxy, carboxyl, amino, hydroxyl and methylol groups).

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an aqueous coating composition using a polymer emulsion containing polysiloxane inside the particles as a vehicle, and more specifically, a water-based coating composition containing a polysiloxane having a reactive polar group. The particle contains a copolymer having a reactive polar group that is reactive with the polysiloxane in the outer layer of the particle.
The present invention relates to an aqueous coating composition that has a crosslinked polymer emulsion as a vehicle and has a coating film that has good storage stability, excellent solvent resistance and waterproofing properties, and high moisture permeability.

(Prior Art) Many types of water-based paints containing polymer emulsions as vehicles have been used from the viewpoint of aesthetics and protection of concrete buildings. One of these is sprayed sand wall material. Paint films using this paint generally have a high pigment concentration, so many fine pores occur in the paint film.
Poor waterproofness. Furthermore, it has poor followability to cracks in concrete, which can be caused by various factors.
It could not be said that the protective function against the concrete surface was sufficient.

Recently, a so-called elastic paint has been applied as a paint that follows cracks in concrete and has excellent waterproof properties.

Further, JP-A-62-127364 discloses a composition using an emulsion of silicone resin and acrylic resin, and JP-A-62-127365 discloses a composition using colloidal silica and acrylic resin. is disclosed.

(Problem B to be solved by the invention) However, since the above-mentioned elastic paint has a large proportion of polymer emulsion in the paint, it certainly has excellent waterproofness and good followability to the base material, but it has poor moisture permeability. Due to the lack of concrete, it is difficult to volatilize the condensation that has formed inside the concrete, resulting in disadvantages such as blistering on the painted film and condensation on the inner wall surface.

In order to compensate for this drawback, the composition according to the above publication was proposed, but the former (Japanese Patent Application Laid-Open No. 127364/1982)
Due to the lack of compatibility between silicone resin and acrylic resin, it cannot be said that the storage stability of the paint is fully satisfied.
The latter (Japanese Unexamined Patent Publication No. 62-127365) is because colloidal silica has poor durability against alkali base materials.
Although it has excellent moisture permeability, it cannot be said that it has sufficient waterproof performance.

In addition, although these paints are sometimes used in one coat, there are many cases in which a solvent-based paint is applied as a top coat. In some cases, the phenomenon of dusting appears on the painted surface and significantly impairs the appearance of the paint, so there has been a desire to develop a paint that exhibits a paint film with good solvent resistance to such solvents.

The purpose of the present invention is to have excellent storage stability, waterproof performance of the coating film,
An object of the present invention is to provide an aqueous coating composition with improved moisture permeability without impairing solvent resistance.

(Means for Solving the Problems) As a result of extensive research to solve the above problems, the present inventors have completed the present invention.

That is, the present invention provides an α,β-ethylenically unsaturated monomer (B) in the presence of a polysiloxane (A) having a reactive polar group.
) with an α,β-ethylenically unsaturated monomer (D) having a reactive polar group that reacts with the reactive polar group of (A) in the presence of an emulsion polymer (C) obtained by emulsion polymerization of This is an aqueous coating composition containing as a vehicle a polymer emulsion obtained by emulsion polymerization of this and a copolymerizable αβ-ethylenically unsaturated monomer (E).

As the polysiloxane (A) used in the present invention, dimethylpolysiloxane having a reactive polar group is generally used, but in order to improve compatibility with the acrylic polymer, the methyl group of the polysiloxane is replaced with an ethyl group or a propyl group. , butyl group, phenyl group, etc. are also effective.

The reactive polar group of the polysiloxane may have various structures, and includes, for example, an epoxy group, a carboxyl group, an amino group, a hydroxyl group, a methylol group, and the like.

These reactive polar groups are preferably located at the ends of the polysiloxane molecules, but those bonded to side chains can also be used, as long as one or more are attached to the polysiloxane molecules.

The α,β-ethylenically unsaturated monomer (D) having a reactive polar group that reacts with the reactive polar group of polysiloxane may have various structures, but monomers containing amino groups Examples include alkylamino esters of acrylic acid or methacrylic acid such as N-methylaminoethyl acrylate or methacrylate, dimethylaminoethyl acrylate or methacrylate, monovinylpyridines such as vinylpyridine, vinyl ethers such as dimethylaminoethyl vinyl ether, N-(2-
Examples include unsaturated amides having an alkylamino group such as dimethylamine ethyl)acrylamide or methacrylamide. Monomers containing carboxyl groups include ethylenically unsaturated basic carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid; ethylenically unsaturated dibasic carboxylic acids such as itaconic acid, maleic acid and fumaric acid; Examples include monoalkyl esters of ethylenically unsaturated dibasic carboxylic acids.

Examples of monomers containing epoxy groups include glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, and the like.

Examples of the monomer containing a hydroxyl group include β-hydroxyethyl acrylate and β-hydroxyethyl methacrylate.

Examples of monomers containing a methylol group include N-methylol acrylamide, N-methylol methacrylamide, N-methylol methacrylamide, and
, N-dimethylol acrylamide, dimethylol itaconamide, and the like.

Examples of the monomer containing an alkoxysilane group include vinyltriethoxysilane, vinyltris(βmethoxyethoxy)silane, and γ-methacryloxypropyltrimethoxysilane.

According to the present invention, the reactive polar groups of polysiloxane A and α
, the reaction with the reactive polar group of the β-ethylenically unsaturated monomer (D) does not necessarily need to occur during emulsion polymerization, and the reaction between emulsion particles that occurs during film formation of a water-based paint using an emulsion as a vehicle. Even when a reaction occurs between reactive polar groups during the film forming process, the effects of the present invention are fully exhibited.

That is, by using the reactive polar group of the present invention, the welt resistance and waterproof properties of the coating film can be dramatically improved.

The combination of the reactive polar group of the polysiloxane (A) and the reactive polar group of the α,β ethylenically unsaturated monomer (D) is as follows: When an epoxy group is used as the reactive polar group of the polysiloxane, It is preferable to use an α, β-ethylenically unsaturated monomer having an amino group or a carboxyl group, and when a carboxyl group is used as the reactive polar group of the polysiloxane, an epoxy group or a hydroxyl group is preferably used. It is preferable to use an α,β-ethylenically unsaturated monomer containing a methylol group or a methylol group. Further, when an amino group is used as the reactive polar group of the polysiloxane, it is preferable to use an α,β-ethylenically unsaturated monomer containing an epoxy group. When a hydroxyl group or a methylol group is used as the reactive polar group of polysiloxane, α, β-containing carboxyl group, alkoxysilane group, or epoxy group
Preference is given to using ethylenically unsaturated monomers.

These α,β-ethylenically unsaturated monomers having a reactive polar group can be used alone or in combination of two or more types.

In the present invention, α,β-ethylenically unsaturated monomer (B
) and other α, β-ethylenically unsaturated monomers (E) copolymerizable with the α, β-ethylenically unsaturated monomer having a reactive polar group that reacts with the reactive polar group of polysiloxane. Examples include acrylic acid esters such as methyl acrylate, ethyl acrylate, and 2-ethylhexyl acrylate; methacrylic acid esters such as methyl methacrylate, ethyl methacrylate, and butyl methacrylate; maleic acid, fumaric acid, and itaconic acid. various esters; vinyl esters such as vinyl acetate and vinyl tertiary carboxylate; styrene, α-
Aromatic compounds such as methylstyrene and vinyltoluene 1
．． Heterocyclic vinyl compounds such as vinylpyrrolidone; vinyl chloride, acrylonitrile, vinyl ether, vinyl ketone, vinyl amide, etc.; halogenated vinylidene compounds such as vinylidene chloride, vinyldene fluoride; α-olefins such as ethylene and propylene; dienes such as butadiene, etc. If desired, monomers having two or more unsaturated bonds in one molecule such as diallyl phthalate, divinylbenzene, allyl acrylate, and trimethylolpropane triacrylate can also be used.

Furthermore, those having an unsaturated group, a sulfonic acid group, or a sulfate group, such as vinyl sulfonic acid, styrene sulfonic acid, and allyl alkyl itaconate sulfate, and their alkali acids can also be used.

Next, a method for emulsion polymerization of the polymer emulsion used in the present invention will be described.

The emulsion polymer (C) containing a polysiloxane having a reactive polar group, which is used as a seed particle in the production of a polymer emulsion, is prepared by dissolving the polysiloxane in an α,β-ethylenically unsaturated monomer (B). After that, it can be easily obtained by emulsion polymerization using a known method.

Another method is to add and disperse the polysiloxane in an aqueous phase containing an emulsifier, and then add a mixture of α,β-ethylenically unsaturated monopoles and a radical generation initiator, and carry out emulsion polymerization by a known method. You may.

Next, the emulsion polymer (C) was added to the aqueous phase, and α and β were added in the same manner.
- A polymer emulsion is produced by adding the ethylenically unsaturated monomer (D) mixture and a radical generation initiator and carrying out emulsion polymerization by a known method. In this case, in addition to the emulsion polymer of the seed particles, an emulsifier may be further added to stabilize polymerization, such as to prevent the formation of aggregates during emulsion polymerization.

In the above method, seed particles are first produced and then emulsion polymerization is carried out using them in the next step, but in addition to this, an emulsion polymer corresponding to the seed particles is produced in the same reaction apparatus, and then, It can also be produced by adding an ethylenically unsaturated monomer mixture and a radical generation initiator to be used in the next step of emulsion polymerization into the system and carrying out emulsion polymerization. That is, in an aqueous phase in which an emulsifier is dissolved, an ethylenically unsaturated monomer mixture serving as seed particles is emulsion polymerized using a radical initiator in the presence of the polysiloxane, and then the ethylenically unsaturated monomer mixture in the next step is polymerized using a radical initiator. The polymer emulsion used in the present invention is obtained by adding a polymer mixture and a radical generation initiator and carrying out emulsion polymerization.

The aqueous coating composition of the present invention is characterized in that it uses an emulsion polymer composition obtained by emulsion polymerization as a vehicle, and the emulsifier used in the production of the emulsion polymer composition is a known emulsifier. I can't help it.

Anionic emulsifiers such as sodium lauryl sulfate, sodium alkylbenzene sulfonate, sodium dioctyl sulfosuccinate, polyoxyethylene alkylphenyl ether sulfate; polyoxyethylene alkyl ether, polyoxyethylene alkylphenyl ether, polyoxyethylene- Nonionic emulsifiers such as polyoxypropylene block copolymers can be appropriately selected and used.

Furthermore, water-soluble oligomers and emulsifiers having α,β-ethylenically unsaturated double bonds, so-called reactive emulsifiers, can also be used alone or in combination with the above-mentioned emulsifiers.

Furthermore, it is also effective to use water-soluble polymeric substances such as polyvinyl alcohol and hydroxyethyl cellulose in combination with the above emulsifier or to add them to the emulsion after polymerization.

As the polymerization initiator used in emulsion polymerization, water-soluble and oil-soluble polymerization initiators are used, and they may be used alone or in combination.

Examples of water-soluble polymerization initiators include hydrogen peroxide, ammonium persulfate, potassium persulfate, and sodium persulfate. Examples of oil-soluble polymerization initiators include 2,2'-azobisisobutyronitrile, 2'2'-azobis-(4-
methoxy-2,4-dimethylvaleronitrile), 2,2
'-Azobis-2,4-dimethylvaleronitrile, 1.
1'-azobiscyclohexane-cyclohexane-1-
Examples include carbonitrile, benzoyl peroxide, lauroyl peroxide, dibutyryl peroxide, diacetyl peroxide, dipropionyl peroxide, cumene hydroperoxide, and the like.

These water-soluble and oil-soluble polymerization initiators and a suitable reducing agent,
For example, so-called redox initiators consisting of ascorbic acid in combination with sulfites or sulfoxylates may be used.

During emulsion polymerization, a chain transfer agent may be used to adjust the molecular weight. Suitable chain transfer agents include mercaptans such as methyl-, ethyl-, propyl-, isopropyl, butyl-, pentyl-, hexyl-, octyl-, decyl-, undecyl-dodecyl-, stearyl-1, etc.
- mercaptobenzoic acid, mercaptoacetic acid, methanol,
Mention may be made of ethanol, propatool, isopropanol, butanol, isobutanol, t-butanol, pentanols, and hexanols.

The temperature during emulsion polymerization may be within the range used in known emulsion polymerization, and emulsion polymerization may be carried out under normal pressure or under gaseous α
, is carried out under pressure when using β-ethylenically unsaturated monomers.

In order to obtain the moisture permeability in the present invention, it is essential to use a polysiloxane having a reactive polar group.
Its properties are greatly influenced by the amount used. That is, if the amount used increases, the moisture permeability will improve, but if the amount is too large, the polymerization stability and storage stability of the polymer emulsion will be impaired.

The appropriate amount is 1 to 300 parts by weight, preferably 5 to 100 parts by weight, based on 100 parts by weight of the total amount of β-ethylenically unsaturated monomers.

Polysiloxane has excellent moisture permeability because the polymer skeleton of polysiloxane has a helical shape, which prevents associated water molecules from passing through, but allows individual water molecules such as water vapor to pass through. it is conceivable that.

Generally, polysiloxane is not compatible with polymers bonded by carbon chains such as vinyl and acrylic.
These polymers can be mixed using auxiliary means such as emulsifiers, or polysiloxane can be mixed with α,
Even if a solution of β-ethylenically unsaturated monomer is polymerized using a conventional emulsion polymerization method, it is difficult to obtain an emulsion with good storage stability because the polysiloxane diffuses into water. In the present invention, seed particles are formed by emulsion polymerization of α, β-ethylenically unsaturated monomers in the presence of polysiloxane, and in the presence of these seed particles, α, β-ethylenically unsaturated monomers are By using a two-step emulsion polymerization method in which emulsion polymerization is carried out, it has become possible to obtain an emulsion containing polysiloxane and having good storage stability.

In addition, by retaining reactive polar groups in each of the polysiloxane and the α,β-ethylenically unsaturated monomer, the solvent resistance and waterproof performance of polymer emulsions containing polysiloxane are dramatically improved. I was able to do it.

The amount of the reactive polar group held by the polysiloxane and the α,β-ethyl-nonsaturated monomer can be changed depending on the required physical properties such as waterproof performance and weather resistance of the water-based paint.

The aqueous coating composition of the present invention is produced in exactly the same manner as in the production of conventional emulsion coatings using the emulsion polymer composition specified above as a vehicle. That is, pigments, fillers, plasters, dispersants, wetting agents, thickeners and/or rheology control agents, antifoaming agents, plasticizers, coating aids, organic solvents, preservatives, anti-pie agents, pl( Conditioners, rust preventives, etc.
They are selected and combined according to their respective purposes, and made into paints using normal methods.

The present invention will be described in more detail with reference to Examples below, but the present invention is not limited to the following Examples.

Note that all parts and percentages below are values based on weight.

Example 1 The following raw materials were charged and dissolved in a reaction vessel No. 1 and 52 equipped with a stirrer, a reflux condenser, a dropping funnel, and a temperature needle.

Deionized water 324. θ section Neuge 7Ea-17os 16.
0 parts The following mixture was then placed in the dropping funnel.

Silicone F-237-5340.0 parts (Nippon Unicar product) Butyl acrylate Methyl methacrylate 200.0 parts Next, while supplying nitrogen gas, the internal temperature of the reaction was brought to 60°C while stirring. ``CL was heated to a concentration of 2% dissolved in deionized water.
40 parts of an aqueous potassium persulfate solution of
Added 0%. While controlling the temperature increase due to polymerization heat using a water bath and keeping the internal temperature at 80°C, the remaining mixture of the polysiloxane and monomer and 80 parts of a 2% potassium persulfate aqueous solution were added over a period of 2 hours. It was added dropwise and polymerized.

After further holding at 80℃ for 2 hours, it was cooled to room temperature for 2 hours.
The mixture was filtered through a 00 mesh filter cloth and taken out to obtain an emulsion polymer as seed particles. This product has a non-volatile concentration of 50.1% and a pH of
It was 4.5.

Emulsion polymer 45 obtained above was added to the same reactor No. 1.51.
2 parts and 125 parts water. Next, the following ethylenically unsaturated monomer mixture was prepared and placed in the dropping funnel.

Butyl acrylate 97.0 parts Methyl methacrylate 97.0 parts Dimethylaminoethyl methacrylate 4.0 parts Acrylic acid
While feeding 2.0 parts of nitrogen gas and stirring, the internal temperature of the reactor was raised to 70°C, and 60 parts of a prepared 2% potassium persulfate aqueous solution and the above monomer mixture were added dropwise to another dropping funnel. and polymerized. These drops were carried out for 2 hours while maintaining the internal temperature at 70°C. Furthermore, at the same temperature 2
After being maintained for a period of time, it was cooled to room temperature and filtered through a 200 mesh filter cloth to obtain the polymer emulsion (E-1) used in the present invention.
I got it. The obtained polymer emulsion (E-1) had a nonvolatile content concentration of 50.1%, a pH of 6.0, and a viscosity of 120 cps.
Met. This emulsion was then mixed neat and p
When H was adjusted to 9.5 with aqueous ammonia and stored at 50''C for one month, all were stable without any changes such as aggregation.

In addition, each emulsion before and after pH adjustment was applied onto a glass plate using a 3 mil applicator, and after drying at room temperature of approximately 25°C for 48 hours, a rubbing test was performed on the surface with a cloth soaked in toluene. As a result, both are 50
Although some damage was observed on the surface due to repeated rubbing, it was not dissolved and disappeared, indicating that a crosslinked film had been formed.

Comparative Example 1 Meanwhile, 40.0 parts of polysiloxane, 4 parts of initial deionized water
A polymer emulsion (RE-1) was obtained by emulsion polymerization in exactly the same manner as in Example 1 except that 0.0 part was removed. The obtained polymer emulsion (RE-1) had a nonvolatile content concentration of 50.1%, a pH of 6.0, and a viscosity of 140 cps. The pH of this product was adjusted to 9.5, and the same rubbing test as in Example 1 was performed, and as a result, complete dissolution was lost after 5 times.

Using each of the polymer emulsions obtained above, water-based coating compositions were produced according to the following formulations.

(Paint formulation) Water 10
．． 0 parts Ethylene glycol (antifreezing agent) 2.6 parts Inflow 540 1.0 parts (Dispersant: Nippon Zeon KK product) Neugen EA-1200, 3 parts (Wetting agent: Daiichi Kogyo Seiyaku KK product) Hestside FX O, 01 copies (
Preservative Nippon Ink Chemical KK product) J R-600A
36.0 parts (titanium oxide: Teikoku Kako K
) (Product) SN-Deformer 121 0.4 part (
Antifoaming agent: Sannopco KK product) Ammonia water (28%) 0.15 parts Emulsion (50%) ioo, o parts Texanol 7.0 parts (filming aid: Eastman, chemical product) Sevenrosize QP-4
400 (3%) 9.2 parts (thickener: Union Carbide product) water
3.75 copies tota1
170.41 parts N, V,
51.0% pigment volume concentration (PVC
) 20% paint and coating film physical property test results are as shown in Table 1.

〔Test method〕

Paint viscosity by Nystomer type viscosity needle. Measurement temperature: 25°C Paint film moisture permeability: Based on the JIS-Z-0208 test method Water permeability: Based on the JIS elongation type test method Water resistance = 20°C
Soak the specimen in water for 7 days and observe changes in the coated surface's gloss, whitening, blistering, etc. Alkali resistance = 20°C Soak in 5% caustic soda solution for 7 days and observe changes in the state of the coated surface Solvent resistance: Toluene 100 using absorbent cotton impregnated with
Rubbing the surface of the coated film and observing changes in the state of the coated surface Example 2 The following materials were prepared as raw materials.

■Polysiloxantore Silicone BY-16-855 (manufactured by Toray Silicone KK) 50.0 parts (epoxy-type dimethylpolysiloxane at both ends) ■Polymerizable monomer (first stage monomer) 2-ethylhexyl acrylate 75.0 Part Styrene 100.0 parts Methyl methacrylate 50.0 parts Acrylic acid
2.0 parts (second stage monomer) 2-ethylhexyl acrylate ioo, o parts Styrene 100.0 parts Methyl methacrylate 55.0 parts Dimethylaminoethyl methacrylate 10.0 parts Methacrylic @
8.0 parts Emulsifier Noigen EA-1705 (solid content 80%) 15
．． 0 parts benolu 2 (solid content 25%) 2
0. θ part ■ Ion exchange water 55
1.0 parts ■ Polymerization initiator ammonium persulfate 2.5 parts 1)
501 parts of deionized water and an emulsifier were charged and dissolved in a reaction vessel No. 1 and 51 equipped with an anion north stirrer manufactured by Kao ■, a reflux condenser, a dropping funnel, and a thermometer. Next, while supplying nitrogen gas,
While stirring, raise the internal temperature of the reactor to 80°C and add 25% of an aqueous solution of ammonium persulfate dissolved in 50 parts of deionized water.
1,000 ml of polysiloxane was added thereto, and then a first layer of 1,000 ml of water in which the polysiloxane was dissolved was added dropwise over 1 hour. Internal temperature 80
After maintaining the temperature at .degree. C. for another 1 hour, the remaining ammonium persulfate aqueous solution was added, and then the second stage monomer was added dropwise over 1 hour to polymerize.

After further holding at 80℃ for 2 hours, it was cooled to room temperature and
Filtered with 00 mesh filter cloth, emulsion polymer emulsion (
E-2) was obtained. This thing has a non-volatile content concentration of 50.1%.
The pH was 4.5. After adjusting this emulsion to 9.5 with aqueous ammonia, a water-based paint composition was produced using the same paint formulation as in Example 1.

Examples 3 to 8 Furthermore, polymer emulsions (E-3 to E-8) were synthesized using the raw materials shown in Table 2 in the same manner as in Example 2, and water-based paint compositions were prepared using the same paint formulation as in Example 1. (Example 3)
~8) was obtained.

On the other hand, polymer emulsions (RE-2 to RE-4) were synthesized using the raw materials shown in Table 2 in the same manner as in Example 2, and water-based paint compositions (RE-2 to RE-4) were synthesized using the same paint formulation as in Example 1. Examples 2 to 4) were obtained.

(Comparative Example 5) After making an emulsion using 5350 parts of polysiloxane silicone F-237-5 and 20 parts of anionic emulsifier Lebenol WZ (solid content 25%), it was added to 200 parts of REL copolymer emulsion. The mixture was thoroughly stirred to obtain a silicone-acrylic blend emulsion.

This emulsion was mixed in the same manner as in Example 1 to obtain an aqueous coating composition.

(Comparative Example 6) To 100 parts of the copolymer emulsion of RE-1, 50 parts of Snowtex C (colloidal silica, solid content 20%, manufactured by Nichiwa Kagaku ■) was added, and after thorough stirring, Example A water-based paint composition was obtained by the same paint formulation as in Example 1.

Table 3 shows the performance test results of the paints and coatings of the aqueous paint compositions of Examples and Comparative Examples.

/ (Effects of the Invention) The aqueous coating composition of the present invention exhibits coating film characteristics that have good storage stability, excellent waterproofing properties, and high moisture permeability.

Claims (1)

[Claims] 1. Emulsion polymer (C) obtained by emulsion polymerization of α,β-ethylenically unsaturated monomer (B) in the presence of polysiloxane (A) having a reactive polar group in the presence of an α,β-ethylenically unsaturated monomer (D) having a reactive polar group that reacts with the reactive polar group of (A) and α, which is copolymerizable therewith.
An aqueous coating composition whose vehicle is a polymer emulsion obtained by emulsion polymerization of a β-ethylenically unsaturated monomer (E). 2. The reactive polar group of the polysiloxane (A) having a reactive polar group is an epoxy group, a carboxyl group, an amino group,
The aqueous coating composition according to claim 1, characterized in that it contains one or more groups selected from hydroxyl groups and methylol groups. 3. The reactive polar group of the α,β-ethylenically unsaturated monomer (D) is one or more selected from an epoxy group, an amino group, a carboxyl group, a hydroxyl group, a methylol group, and an alkoxysilane group. The aqueous coating composition according to claim 1, characterized in that: 4. The reactive polar group of the polysiloxane (A) having a reactive polar group is an epoxy group, and the reactive polar group of the α,β-ethylenically unsaturated monomer (D) is an amino group or a carboxyl group. The aqueous coating composition according to claim 1, characterized in that: 5. The reactive polar group of the polysiloxane (A) having a reactive polar group is a carboxyl group, and the reactive polar group of the α,β-ethylenically unsaturated monomer (D) is an epoxy group, a hydroxyl group, or a methylol group. The aqueous coating composition according to claim 1, characterized in that it is one or more selected from the group consisting of: 6. The reactive polar group of the polysiloxane (A) having a reactive polar group is an amino group, and the reactive polar group of the α,β-ethylenically unsaturated monomer (D) is an epoxy group. The aqueous coating composition according to claim 1, characterized in that: 7. The reactive polar group of the polysiloxane (A) having a reactive polar group is a hydroxyl group or a methylol group, and the reactive polar group of the α,β-ethylenically unsaturated monomer (D) is a carboxyl group or an alkoxy group. The water-based coating composition according to claim 1, characterized in that it contains one or more selected from silane groups and epoxy groups. 8. Any one of claims 1 to 6, wherein the amount of polysiloxane (A) having a reactive polar group is 5 to 100 parts by weight based on 100 parts by weight of the α,β-ethylenically unsaturated monomer. The aqueous coating composition according to (1).